JP4508380B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

【００９２】
（式中、ｎは、２以上の整数を表す。）
【００９３】
【化２】

【００９４】
（式中、ｍは、２以上の整数を表す。また、Ｒ¹ 、Ｒ² は、メチレン基、エチレン基または−ＣＨ₂ −Ｏ−ＣＨ₂ −を表し、両者は同一であってもよいし、異なっていてもよい。）
【００９５】
また、上記化学式（２）で表される繰り返し単位を有する熱可塑性ポリフェニレンエーテル樹脂は、ベンゼン環にメチル基が結合した構造を有しているが、本発明で用いることのできるポリフェニレンエーテル樹脂としては、上記メチル基が、エチル基等の他のアルキル基等で置換された誘導体や、メチル基の水素がフッ素で置換された誘導体等であってもよい。
【００９６】
また、上記熱可塑性樹脂としては、フェノキシ樹脂、ポリエーテルスルフォン、ポリスルフォン等が挙げられる。
また、これらの複合体（樹脂複合体）としては、熱硬化性樹脂と熱可塑性樹脂とを含むものであれば特に限定されず、その具体例としては、例えば、粗化面形成用樹脂組成物等が挙げられる。
【００９７】
上記粗化面形成用樹脂組成物としては、例えば、酸、アルカリおよび酸化剤から選ばれる少なくとも１種からなる粗化液に対して難溶性の未硬化の耐熱性樹脂マトリックス中に、酸、アルカリおよび酸化剤から選ばれる少なくとも１種からなる粗化液に対して可溶性の物質が分散されたもの等が挙げられる。
なお、上記「難溶性」および「可溶性」という語は、同一の粗化液に同一時間浸漬した場合に、相対的に溶解速度の早いものを便宜上「可溶性」といい、相対的に溶解速度の遅いものを便宜上「難溶性」と呼ぶ。
【００９８】
上記耐熱性樹脂マトリックスとしては、層間樹脂絶縁層に上記粗化液を用いて粗化面を形成する際に、粗化面の形状を保持できるものが好ましく、例えば、熱硬化性樹脂、熱可塑性樹脂、これらの複合体等が挙げられる。また、感光性樹脂を用いることにより、層間樹脂絶縁層に露光、現像処理を用いてバイアホール用開口を形成してもよい。
【００９９】
上記熱硬化性樹脂としては、例えば、エポキシ樹脂、フェノール樹脂、ポリイミド樹脂、ポリオレフィン樹脂、フッ素樹脂等が挙げられる。また、上記熱硬化性樹脂を感光化する場合は、メタクリル酸やアクリル酸等を用い、熱硬化基を（メタ）アクリル化反応させる。特にエポキシ樹脂の（メタ）アクリレートが望ましい。さらに、１分子中に、２個以上のエポキシ基を有するエポキシ樹脂がより望ましい。上述の粗化面を形成することができるばかりでなく、耐熱性等にも優れているため、ヒートサイクル条件下においても、導体回路に応力の集中が発生せず、導体回路と層間樹脂絶縁層との間で剥離が発生しにくい。
【０１００】
上記熱可塑性樹脂としては、例えば、ポリエーテルスルフォン、ポリスルフォン、ポリフェニレンスルフォン、ポリフェニレンサルファイド、ポリフェニルエーテル、ポリエーテルイミド等が挙げられる。これらは単独で用いてもよいし、２種以上併用してもよい。
【０１０１】
上記酸、アルカリおよび酸化剤から選ばれる少なくとも１種からなる粗化液に対して可溶性の物質は、無機粒子、樹脂粒子、金属粒子、ゴム粒子、液相樹脂および液相ゴムから選ばれる少なくとも１種であることが望ましい。
【０１０２】
上記無機粒子としては、例えば、アルミニウム化合物、カルシウム化合物、カリウム化合物、マグネシウム化合物、ケイ素化合物等が挙げられる。これらは単独で用いてもよいし、２種以上併用してもよい。
【０１０３】
上記アルミニウム化合物としては、例えば、アルミナ、水酸化アルミニウム等が挙げられ、上記カルシウム化合物としては、例えば、炭酸カルシウム、水酸化カルシウム等が挙げられ、上記カリウム化合物としては、例えば、炭酸カリウム等が挙げられ、上記マグネシウム化合物としては、例えば、マグネシア、ドロマイト、塩基性炭酸マグネシウム、タルク等が挙げられ、上記ケイ素化合物としては、例えば、シリカ、ゼオライト等が挙げられる。これらは単独で用いてもよいし、２種以上併用してもよい。
【０１０４】
上記アルミナ粒子は、ふっ酸で溶解除去することができ、炭酸カルシウムは塩酸で溶解除去することができる。また、ナトリウム含有シリカやドロマイトはアルカリ水溶液で溶解除去することができる。
【０１０５】
上記樹脂粒子としては、例えば、熱硬化性樹脂、熱可塑性樹脂等からなるものが挙げられ、酸、アルカリおよび酸化剤から選ばれる少なくとも１種からなる粗化液に浸漬した場合に、上記耐熱性樹脂マトリックスよりも溶解速度の早いものであれば特に限定されず、具体的には、例えば、アミノ樹脂（メラミン樹脂、尿素樹脂、グアナミン樹脂等）、エポキシ樹脂、フェノール樹脂、フェノキシ樹脂、ポリイミド樹脂、ポリフェニレン樹脂、ポリオレフィン樹脂、フッ素樹脂、ビスマレイミド−トリアジン樹脂等挙げられる。これらは、単独で用いてもよく、２種以上併用してもよい。
【０１０６】
なお、上記エポキシ樹脂は、酸や酸化剤に溶解するものや、これらに難溶性のものを、オリゴマーの種類や硬化剤を選択することにより任意に製造することができる。例えば、ビスフェノールＡ型エポキシ樹脂をアミン系硬化剤で硬化させた樹脂はクロム酸に非常によく溶けるが、クレゾールノボラック型エポキシ樹脂をイミダゾール硬化剤で硬化させた樹脂は、クロム酸には溶解しにくい。
【０１０７】
上記樹脂粒子は予め硬化処理されていることが必要である。硬化させておかないと上記樹脂粒子が樹脂マトリックスを溶解させる溶剤に溶解してしまうため、均一に混合されてしまい、酸や酸化剤で樹脂粒子のみを選択的に溶解除去することができないからである。
【０１０８】
上記金属粒子としては、例えば、金、銀、銅、スズ、亜鉛、ステンレス、アルミニウム、ニッケル、鉄、鉛等が挙げられる。これらは、単独で用いてもよく、２種以上併用してもよい。
また、上記金属粒子は、絶縁性を確保するために、表層が樹脂等により被覆されていてもよい。
【０１０９】
上記ゴム粒子としては、例えば、アクリロニトリル−ブタジエンゴム、ポリクロロプレンゴム、ポリイソプレンゴム、アクリルゴム、多硫系剛性ゴム、フッ素ゴム、ウレタンゴム、シリコーンゴム、ＡＢＳ樹脂等が挙げられる。
【０１１０】
また、上記ゴム粒子として、例えば、ポリブタジエンゴム、エポキシ変性、ウレタン変性、（メタ）アクリロニトリル変性等の各種変性ポリブタジエンゴム、カルボキシル基を含有した（メタ）アクリロニトリル・ブタジエンゴム等を使用することもできる。これらのゴム粒子を使用することにより、該ゴム粒子が酸あるいは酸化剤に溶解しやすくなる。つまり、酸を用いてゴム粒子を溶解する際には、強酸以外の酸でも溶解することができ、酸化剤を用いてゴム粒子を溶解する際には、比較的酸化力の弱い過マンガン酸でも溶解することができる。また、クロム酸を用いた場合でも、低濃度で溶解することができる。そのため、酸や酸化剤が層間樹脂絶縁層表面に残留することがなく、後述するように、粗化面形成後、塩化パラジウム等の触媒を付与する際に、触媒が付与されなかったり、触媒が酸化されたりすることがない。これらは、単独で用いてもよく、２種以上併用してもよい。
【０１１１】
上記可溶性の物質を、２種以上混合して用いる場合、混合する２種の可溶性の物質の組み合わせとしては、樹脂粒子と無機粒子との組み合わせが望ましい。両者とも導電性が低くいため、層間樹脂絶縁層の絶縁性を確保することができるとともに、難溶性樹脂との間で熱膨張の調整が図りやすく、粗化面形成用樹脂組成物からなる層間樹脂絶縁層にクラックが発生せず、層間樹脂絶縁層と上層導体回路との間で剥離が発生しないからである。
【０１１２】
上記液相樹脂としては、上記熱硬化性樹脂の未硬化溶液を使用することができ、このような液相樹脂の具体例としては、例えば、未硬化のエポキシオリゴマーとアミン系硬化剤の混合液等が挙げられる。
上記液相ゴムとしては、例えば、上記したポリブタジエンゴム、エポキシ変性、ウレタン変性、（メタ）アクリロニトリル変性等の各種変性ポリブタジエンゴム、カルボキシル基を含有した（メタ）アクリロニトリル・ブタジエンゴム等の未硬化溶液等を使用することができる。
【０１１３】
上記液相樹脂や液相ゴムを用いて上記感光性樹脂組成物を調製する場合には、耐熱性樹脂マトリックスと可溶性の物質とが均一に相溶しない（つまり相分離するように）ように、これらの物質を選択する必要がある。
上記基準により選択された耐熱性樹脂マトリックスと可溶性の物質とを混合することにより、上記耐熱性樹脂マトリックスの「海」の中に液相樹脂または液相ゴムの「島」が分散している状態、または、液相樹脂または液相ゴムの「海」の中に、耐熱性樹脂マトリックスの「島」が分散している状態の感光性樹脂組成物を調製することができる。
【０１１４】
そして、このような状態の感光性樹脂組成物を硬化させた後、「海」または「島」の液相樹脂または液相ゴムを除去することにより粗化面を形成することができる。
【０１１５】
上記粗化液として用いる酸としては、例えば、リン酸、塩酸、硫酸、硝酸や、蟻酸、酢酸等の有機酸等が挙げられるが、これらのなかでは有機酸を用いることが望ましい。粗化処理した場合に、バイアホールから露出する金属導体層を腐食させにくいからである。
上記酸化剤としては、例えば、クロム酸、クロム硫酸、アルカリ性過マンガン酸塩（過マンガン酸カリウム等）の水溶液等を用いることが望ましい。
また、上記アルカリとしては、水酸化ナトリウム、水酸化カリウム等の水溶液が望ましい。
【０１１６】
上記可溶性の物質の平均粒径は、１０μｍ以下が望ましい。
また、平均粒径が２μｍ以下の平均粒径の相対的に大きな粗粒子と平均粒径が相対的に小さな微粒子とを組み合わせて使用してもよい。即ち、平均粒径が０．１〜０．５μｍの可溶性の物質と平均粒径が１〜２μｍの可溶性の物質とを組み合わせる等である。
【０１１７】
このように、平均粒子と相対的に大きな粗粒子と平均粒径が相対的に小さな微粒子とを組み合わせることにより、無電解めっき膜の溶解残渣をなくし、めっきレジスト下のパラジウム触媒量を少なくし、さらに、浅くて複雑な粗化面を形成することができる。
さらに、複雑な粗化面を形成することにより、粗化面の凹凸が小さくても実用的なピール強度を維持することができる。
上記粗粒子は平均粒径が０．８μｍを超え２．０μｍ未満であり、微粒子は平均粒径が０．１〜０．８μｍであることが望ましい。
【０１１８】
上記粗粒子と微粒子とを組み合わせることにより、浅くて複雑な粗化面を形成することができるのは、使用する粒子径が粗粒子で平均粒径２μｍ未満であると、これらの粒子が溶解除去されても形成されるアンカーは浅くなり、また、除去される粒子は、相対的に粒子径の大きな粗粒子と相対的に粒子径の小さな微粒子の混合粒子であるから、形成される粗化面が複雑になるのである。このような複雑な粗化面を形成することにより、浅い粗化面でも実用的なピール強度を維持することができる。
【０１１９】
また、この場合、使用する粒子径が、粗粒子で平均粒径２μｍ未満であると、粗化が進行しすぎて空隙を発生させることはなく、形成した層間樹脂絶縁層は層間絶縁性に優れている。
なお、上記粗化面形成用樹脂組成物において、可溶性の物質の粒径とは、可溶性の物質の一番長い部分の長さである。
【０１２０】
また、粗粒子は平均粒径が０．８μｍを超え２．０μｍ未満であり、微粒子は平均粒径が０．１〜０．８μｍであると、粗化面の深さは概ねＲｍａｘ＝３μｍ程度となり、セミアディテイブ法では、無電解めっき膜をエッチング除去しやすいだけではなく、無電解めっき膜下のパラジウム触媒をも簡単に除去することができ、また、実用的なピール強度１．０〜１．３ｋｇ／ｃｍを維持することができる。
【０１２１】
上記可溶性の物質の形状は特に限定されず、球状、破砕状等が挙げられる。また、上記可溶性の物質の形状は、一様な形状であることが望ましい。均一な粗さの凹凸を有する粗化面を形成することができるからである。
【０１２２】
上記粗化面形成用樹脂組成物は基板上等に塗布することができるように有機溶剤を含有するものであってもよいし、基板上等に圧着することができるようにフィルム状に成形されたもの（以下、粗化面形成用樹脂フィルムともいう）でもよい。
上記粗化面形成用樹脂組成物が有機溶剤を含有する場合、その含有量は、１０重量％以下であることが望ましい。
【０１２３】
上記粗化面形成用樹脂フィルムにおいて、上記可溶性の物質は、上記耐熱性樹脂マトリックス中にほぼ均一に分散されていることが望ましい。均一な粗さの凹凸を有する粗化面を形成することができ、樹脂フィルムにバイアホールやスルーホールを形成しても、その上に形成する上層導体回路との密着性を確保することができるからである。また、上記粗化面形成用樹脂フィルムは、粗化面を形成する表層部だけに可溶性の物質を含有するよう形成されていてもよい。それによって、粗化面形成用樹脂フィルムの表層部以外は酸または酸化剤にさらされることがないため、層間樹脂絶縁層を介した導体回路間の絶縁性が確実に保たれる。
【０１２４】
上記粗化面形成用樹脂フィルムにおいて、難溶性樹脂中に分散している可溶性の物質の配合量は、粗化面形成用樹脂フィルムに対して、３〜４０重量％が望ましい。可溶性の物質の配合量が３重量％未満では、所望の凹凸を有する粗化面を形成することができない場合があり、４０重量％を超えると、酸または酸化剤を用いて可溶性の物質を溶解した際に、樹脂フィルムの深部まで溶解してしまい、樹脂フィルムからなる層間樹脂絶縁層を介した導体回路間の絶縁性を維持できず、短絡の原因となる場合がある。
【０１２５】
上記粗化面形成用樹脂フィルムは、上記可溶性の物質、上記耐熱性樹脂マトリックス以外に、硬化剤、その他の成分等を含有していることが望ましい。
上記硬化剤としては、例えば、イミダゾール系硬化剤、アミン系硬化剤、グアニジン系硬化剤、これらの硬化剤のエポキシアダクトやこれらの硬化剤をマイクロカプセル化したもの、トリフェニルホスフィン、テトラフェニルホスフォニウム・テトラフェニルボレート等の有機ホスフィン系化合物等が挙げられる。
【０１２６】
上記硬化剤の含有量は、粗化面形成用樹脂フィルムに対して０．０５〜１０重量％であることが望ましい。０．０５重量％未満では、粗化面形成用樹脂フィルムの硬化が不充分であるため、酸や酸化剤が粗化面形成用樹脂フィルムに侵入する度合いが大きくなり、粗化面形成用樹脂フィルムの絶縁性が損なわれることがある。一方、１０重量％を超えると、過剰な硬化剤成分が樹脂の組成を変性させることがあり、信頼性の低下を招いたりしてしまうことがある。
【０１２７】
上記その他の成分としては、例えば、粗化面の形成に影響しない無機化合物あるいは樹脂等のフィラーが挙げられる。上記無機化合物としては、例えば、シリカ、アルミナ、ドロマイト等が挙げられ、上記樹脂としては、例えば、ポリイミド樹脂、ポリアクリル樹脂、ポリアミドイミド樹脂、ポリフェニレン樹脂、メラニン樹脂、オレフィン系樹脂等が挙げられる。これらのフィラーを含有させることによって、熱膨脹係数の整合や耐熱性、耐薬品性の向上等を図りプリント配線板の性能を向上させることができる。
【０１２８】
また、上記粗化面形成用樹脂フィルムは、溶剤を含有していてもよい。上記溶剤としては、例えば、アセトン、メチルエチルケトン、シクロヘキサノン等のケトン類、酢酸エチル、酢酸ブチル、セロソルブアセテートやトルエン、キシレン等の芳香族炭化水素等が挙げられる。これらは単独で用いてもよいし、２種以上併用してもよい。
【０１２９】
（５）次に、その材料として熱硬化性樹脂や樹脂複合体を用いた層間樹脂絶縁層を形成する場合には、未硬化の樹脂絶縁層に硬化処理を施すとともに、バイアホール用開口を形成し、層間樹脂絶縁層とする。また、この工程では、必要に応じて、貫通孔を形成してもよい。
上記バイアホール用開口は、レーザ処理により形成することが望ましい。上記レーザ処理は、上記硬化処理前に行ってもよいし、硬化処理後に行ってもよい。
また、感光性樹脂からなる層間樹脂絶縁層を形成した場合には、露光、現像処理を行うことにより、バイアホール用開口を設けてもよい。なお、この場合、露光、現像処理は、上記硬化処理前に行う。
【０１３０】
また、その材料として熱可塑性樹脂を用いた層間樹脂絶縁層を形成する場合には、熱可塑性樹脂からなる樹脂層にレーザ処理によりバイアホール用開口を形成し、層間樹脂絶縁層とすることができる。
【０１３１】
このとき、使用するレーザとしては、例えば、炭酸ガスレーザ、エキシマレーザ、ＵＶレーザ、ＹＡＧレーザ等が挙げられる。
これらのレーザは、形成するバイアホール用開口や貫通孔の形状等を考慮して使い分けてもよい。
【０１３２】
上記バイアホール用開口を形成する場合、マスクを介して、ホログラム方式のエキシマレーザによるレーザ光照射することにより、一度に多数のバイアホール用開口を形成することができる。
また、短パルスの炭酸ガスレーザを用いて、バイアホール用開口を形成すると、開口内の樹脂残りが少なく、開口周縁の樹脂に対するダメージが小さい。
【０１３３】
また、光学系レンズとマスクとを介してレーザ光を照射することにより、一度に多数のバイアホール用開口を形成することができる。
光学系レンズとマスクとを介することにより、同一強度で、かつ、照射角度が同一のレーザ光を複数の部分に同時に照射することができるからである。
【０１３４】
上記マスクに形成された貫通孔は、レーザ光のスポット形状を真円にするために、真円であることが望ましく、上記貫通孔の径は、０．１〜２ｍｍ程度が望ましい。
また、上記炭酸ガスレーザを用いる場合、そのパルス間隔は、１０^-4〜１０^-8秒であることが望ましい。また、開口を形成するためのレーザを照射する時間は、１０〜５００μ秒であることが望ましい。
【０１３５】
レーザ光にてバイアホール用開口を形成した場合、特に炭酸ガスレーザを用いた場合には、デスミア処理を行うことが望ましい。上記デスミア処理は、クロム酸、過マンガン酸塩等の水溶液からなる酸化剤を使用して行うことができる。また、酸素プラズマ、ＣＦ₄ と酸素の混合プラズマやコロナ放電等で処理してもよい。また、低圧水銀ランプを用いて紫外線を照射することにより、表面改質することもできる。
【０１３６】
上記層間樹脂絶縁層の厚さは特に限定されないが、５〜５０μｍが望ましい。
上記厚さが５μｍ未満であると、上下に隣合う導体回路間の絶縁性が維持できない場合があり、一方、５０μｍを超えると、バイアホール用開口等を形成した際に、その底部に樹脂残りが発生したり、そのバイアホール用開口等の形状が底部に向かって先細り形状になることがある。
また、上記バイアホール用開口の開口径は特に限定されないが、通常、４０〜２００μｍが望ましい。
【０１３７】
また、層間樹脂絶縁層を形成した基板に、貫通孔を形成する場合には、直径５０〜３００μｍのドリル、レーザ光等を用いて貫通孔を形成する。
上記貫通孔を形成した場合、後述する工程において、貫通孔の内壁面に導体層を形成することにより、スルーホールとすることができ、該スルーホールを形成することにより、上記基板および上記層間樹脂絶縁層を介した導体回路間を電気的に接続することができる。
【０１３８】
（６）次に、バイアホール用開口の内壁を含む層間樹脂絶縁層の表面と上記工程で貫通孔を形成した場合には貫通孔の内壁とに、必要に応じて、酸または酸化剤を用いて粗化面を形成する。
上記酸としては、硫酸、硝酸、塩酸、リン酸、蟻酸等が挙げられ、上記酸化剤としては、クロム酸、クロム硫酸、過マンガン酸ナトリウム等の過マンガン酸塩等が挙げられる。
また、上記粗化面の形成は、プラズマ処理等を用いて行ってもよい。
【０１３９】
具体的には、層間樹脂絶縁層を粗化面形成用樹脂組成物等を用いて形成した場合には、酸や酸化剤を用いて粗化面を形成することが望ましく、ポリオレフィン系樹脂等を用いて形成した場合には、プラズマ処理等を用いて粗化面を形成することが望ましい。
【０１４０】
この粗化面は、層間樹脂絶縁層とその上に形成する無電解めっき膜との密着性を高めるために形成するものであり、上記層間樹脂絶縁層と上記無電解めっき膜との間に充分な密着性がある場合には形成しなくてもよい。
【０１４１】
その後、酸を用いて粗化面を形成した場合はアルカリ等の水溶液を用い、酸化剤を用いて粗化面を形成した場合は中和液を用いて、バイアホール用開口内や貫通孔内を中和する。この操作により酸や酸化剤を除去し、次工程に影響を与えないようにする。
【０１４２】
（７）次に、形成された粗化面に、必要により、触媒を付与する。該触媒としては、上述したパラジウム等が挙げられる。
このとき、触媒を確実に付与するために、酸素、窒素等のプラズマ処理やコロナ処理等のドライ処理を施すことにより、酸または酸化剤の残渣を除去するとともに層間樹脂絶縁層の表面を改質することにより、触媒を確実に付与し、無電解めっき時の金属の析出、および、無電解めっき層の層間樹脂絶縁層への密着性を向上させることができ、特に、バイアホール用開口の底面において、大きな効果が得られる。
【０１４３】
（８）次に、バイアホール用開口の内壁面を含む層間樹脂絶縁層の表面に、薄膜導体層を形成する。
上記薄膜導体層は、無電解めっき、スパッタリング、蒸着等の方法を用いて形成することができる。
また、上記層間樹脂絶縁層に粗化面を形成しなかった場合は、上記薄膜導体層をスパッタリングにより形成することが望ましい。
【０１４４】
上記薄膜導体層の形成方法は、層間樹脂絶縁層の材質に応じて選択することが望ましい。
具体的には、粗化面形成用樹脂組成物からなる層間樹脂絶縁層に薄膜導体層を形成する場合は、無電解めっきにより形成することが望ましく、その厚さは０．６〜１．２μｍが望ましい。
なお、この場合には、上述した無電解めっき用前処理液を用いて、層間樹脂絶縁層に前処理を施しておくことが望ましい。
また、ポリオレフィン系樹脂等の低誘電樹脂フィルムからなる層間樹脂絶縁層に薄膜導体層を形成する場合は、スパッタリングや蒸着により形成することが望ましく、その厚さは０．１〜１．０μｍが望ましい。また、このとき形成する薄膜導体層は、ニッケルと銅との二層からなるものが望ましい。また、スパッタリング等により形成した薄膜導体層の上に無電解めっきからなる層を形成してもよい。
【０１４５】
また、上記（５）の工程で貫通孔を形成した場合は、この工程で貫通孔の内壁面にも金属からなる薄膜導体層を形成することにより、スルーホールとしてもよい。
上記（８）の工程で、スルーホールを形成した場合には、以下のような処理工程を行うことが望ましい。即ち、無電解めっき層表面とスルーホール内壁とを黒化（酸化）−還元処理、エッチング処理、Ｃｕ−Ｎｉ−Ｐ針状合金めっきによる処理等を用いて粗化形成処理を行う。この後、さらに、樹脂充填材等を用いてスルーホール内を充填し、ついで、樹脂充填材の表層部と無電解めっき膜表面とをバフ研磨等の研磨処理方法を用いて、平坦化する。
さらに、無電解めっきを行い、既に形成した無電解めっき膜と樹脂充填材の表層部とに無電解めっき層を形成することにより、スルーホールの上に蓋めっき層を形成する。なお、この場合にも、上述した無電解めっき用前処理液を用いて、樹脂充填材の表層部等の被めっき物に前処理を施しておくことが望ましい。
【０１４６】
（９）次に、上記薄膜導体層の形成された層間樹脂絶縁層上の一部にドライフィルムを用いてめっきレジストを形成し、その後、上記薄膜導体層をめっきリードとして電気めっきを行い、上記めっきレジスト非形成部に電解めっき層を形成する。
このとき、バイアホール用開口を電解めっきで充填してフィールドビア構造としてもよく、バイアホール用開口に導電性ペースト等を充填した後、その上に蓋めっき層を形成してフィールドビア構造としてもよい。フィールドビア構造を形成することにより、バイアホールの直上にバイアホールを形成することができる。
【０１４７】
（１０）上記電解めっき層を形成した後、めっきレジストを剥離し、めっきレジストの下に存在していた金属からなる薄膜導体層をエッチングにより除去し、独立パターンの上層導体回路とする。
上記エッチング液としては、例えば、硫酸／過酸化水素水、塩化第二鉄、塩化第二銅、過硫酸アンモニウム等の過硫酸塩の水溶液、塩酸、硝酸、熱希硫酸等を用いることができる。また、第二銅錯体と有機酸とを含有するエッチング液を用いて、無電解めっき膜を除去するとともに、上層導体回路の表面に粗化面を形成してもよい。
さらに、必要により、酸または酸化剤を用いて層間樹脂絶縁層上の触媒を除去してもよい。触媒を除去することにより、触媒に用いたパラジウム等の金属がなくなるため、電気特性の低下を防止することができる。
【０１４８】
（１１）次に、必要により、（２）に記載した方法と同様の方法で上層導体回路の粗化処理を行った後、（４）〜（１０）の工程を繰り返すことにより、下層導体回路が形成された基板上に、層間樹脂絶縁層と上層導体回路とが順次積層された基板を製造することができる。
【０１４９】
（１２）次に、最上層の上層導体回路を含む基板面にソルダーレジスト層を形成し、さらに、該ソルダーレジスト層を開口して半田パッドを形成した後、上記半田パッドに半田ペーストを充填し、リフローすることにより半田バンプを形成する。その後、外部基板接続面に、ピンを配設したり、半田ボールを形成したりすることにより、ＰＧＡ(Pin Grid Array)やＢＧＡ(Ball Grid Array) とする。
【０１５０】
上記ソルダーレジスト層は、例えば、ポリフェニレンエーテル樹脂、ポリオレフィン樹脂、フッ素樹脂、熱可塑性エラストマー、エポキシ樹脂、ポリイミド樹脂等からなるソルダーレジスト組成物を用いて形成することができ、これらの樹脂の具体例としては、例えば、層間樹脂絶縁層に用いた樹脂と同様の樹脂等が挙げられる。
【０１５１】
また、上記以外のソルダーレジスト組成物としては、例えば、ノボラック型エポキシ樹脂の（メタ）アクリレート、イミダゾール硬化剤、２官能性（メタ）アクリル酸エステルモノマー、分子量５００〜５０００程度の（メタ）アクリル酸エステルの重合体、ビスフェノール型エポキシ樹脂等からなる熱硬化性樹脂、多価アクリル系モノマー等の感光性モノマー、グリコールエーテル系溶剤などを含むペースト状の流動体が挙げられ、その粘度は２５℃で１〜１０Ｐａ・ｓに調整されていることが望ましい。
上記ノボラック型エポキシ樹脂の（メタ）アクリレートとしては、例えば、フェノールノボラックやクレゾールノボラックのグリシジルエーテルをアクリル酸やメタクリル酸等と反応させたエポキシ樹脂等が挙げられる。
【０１５２】
上記２官能性（メタ）アクリル酸エステルモノマーとしては特に限定されず、例えば、各種ジオール類のアクリル酸やメタクリル酸のエステル等が挙げられ、その市販品としては、日本化薬社製のＲ−６０４、ＰＭ２、ＰＭ２１等が挙げられる。
【０１５３】
また、上記ソルダーレジスト組成物は、エラストマーや無機フィラーが配合されていてもよい。
エラストマーが配合されていることにより、形成されるソルダーレジスト層は、エラストマーの有する柔軟性および反発弾性により、ソルダーレジスト層に応力が作用した場合でも、該応力を吸収したり、緩和したりすることができ、その結果、多層プリント配線板の製造工程や製造した多層プリント配線板にＩＣチップ等の電子部品を搭載した後のソルダーレジスト層にクラックや剥離が発生することを抑制でき、さらに、クラックが発生した場合でも該クラックが大きく成長することができない。
上記ソルダーレジスト層を開口する方法としては、例えば、バイアホール用開口を形成する方法と同様に、レーザ光を照射する方法等が挙げられる。
【０１５４】
また、ソルダーレジスト組成物として、感光性のソルダーレジスト組成物を使用した場合には、ソルダーレジスト層を形成した後、該ソルダーレジスト層上にフォトレジストを載置し、露光現像処理を施すことにより、ソルダーレジスト層を開口することができる。
【０１５５】
上記ソルダーレジスト層を開口することにより露出した上層導体回路部分は、通常、ニッケル、パラジウム、金、銀、白金等の耐食性金属により被覆することが望ましい。具体的には、ニッケル−金、ニッケル−銀、ニッケル−パラジウム、ニッケル−パラジウム−金等の金属により被覆層を形成することが望ましい。
上記被覆層は、例えば、めっき、蒸着、電着等により形成することができるが、これらのなかでは、被覆層の均一性に優れるという点からめっきが望ましい。
なお、製品認識文字などを形成するための文字印刷工程やソルダーレジスト層の改質のために、酸素や四塩化炭素などのプラズマ処理を適時行ってもよい。
【０１５６】
次に、第二の本発明の多層プリント配線板の製造方法について説明する。
第二の本発明の多層プリント配線板の製造方法は、下層導体回路の形成された基板上に、層間樹脂絶縁層と上層導体回路とが順次積層され、これらの導体回路がバイアホールを介して接続されてなる多層プリント配線板の製造方法であって、少なくとも下記（ａ）〜（ｇ）の下層導体回路を形成する工程を含むことを特徴とする。
（ａ）上記基板上に金属層を形成する工程、
（ｂ）上記金属層および上記基板に、順次、開口形成処理を施し、該開口形成処理により、上記金属層が形成された基板に貫通孔を形成する工程、
（ｃ）上記貫通孔の形成された基板に、０．０１〜０．２５ｍｏｌ／ｌのアルカリ性化合物、および、０．１〜０．３ｍｏｌ／ｌの還元剤を含む水溶液からなる無電解めっき用前処理液を用いた前処理を施す工程、
（ｄ）上記前処理が施された基板の表面に無電解めっき膜を形成する工程、
（ｅ）上記無電解めっき膜上に電解めっき膜を形成する工程、
（ｆ）上記電解めっき膜上の一部に、エッチングレジストを形成する工程、および、
（ｇ）上記エッチングレジストを非形成部下の電解めっき膜と無電解めっき膜と金属層とをエッチング処理により除去する工程。
【０１５７】
第二の本発明の多層プリント配線板の製造方法によれば、スルーホールを含む基板上の下層導体回路を形成するための無電解めっき処理を施す前に、第一の本発明の多層プリント配線板の製造方法で用いる無電解めっき用前処理液と同様の前処理液を用いて、貫通孔の形成された基板に前処理を施すため、無電解めっき処理により基板との密着性に優れた、均一な無電解めっき膜を形成することができ、その結果、接続信頼性、電気特性に優れる多層プリント配線板を製造することができる。
【０１５８】
第二の本発明の多層プリント配線板の製造方法（以下、単に第二の製造方法ともいう）は、第一の製造方法と比べて、（ｄ）〜（ｇ）の工程、即ち、前処理が施された基板の表面に無電解めっき膜を形成した後、電解めっき処理等を経て基板上に下層導体回路を形成する工程のみが異なる。従って、第二の製造方法については、この（ｄ）〜（ｇ）の工程についてのみ詳細に説明することとし、これ以外の製造工程については、簡単に説明することとする。
【０１５９】
まず、第二の製造方法における（ａ）〜（ｇ）の工程について説明する。
第二の製造方法においては、第一の製造方法における（ａ）〜（ｄ）の工程と同様して、前処理が施された基板の表面、即ち、貫通孔の壁面および基板上の金属層の表面に、無電解めっき膜を形成する（工程（ａ）〜（ｄ））。
【０１６０】
次に、上記（ａ）〜（ｄ）工程で形成した無電解めっき膜上に電解めっき膜を形成する（工程（ｅ））。
上記電解めっき膜の形成は、既に形成した無電解めっき膜をめっきリードとして行うことができる。
具体的には、例えば、硫酸、硫酸銅および添加剤を含む電解めっき液を用いることにより電解銅めっき膜を形成することができる。
【０１６１】
次に、電解めっき膜の一部、即ち、下層導体回路形成部分に相当する部分にエッチングレジストを形成する（工程（ｆ））。
上記エッチングレジストは、例えば、感光性ドライフィルムを張り付けたり、液状レジストを塗布した後、露光現像処理を施すことにより形成することができる。
【０１６２】
次に、エッチング処理を施すことにより、上記エッチングレジスト非形成部下の電解めっき膜と無電解めっき膜と金属層とを除去する（工程（ｇ））。その後、上記エッチングレジストを強アルカリ水溶液等を用いて除去する。
ここで、無電解めっき膜および金属層の除去に用いるエッチング液としては、例えば、硫酸−過酸化水素水溶液、過硫酸アンモニウム、過硫酸カリウム等の過硫酸塩水溶液、塩化第二鉄、塩化第二銅等の水溶液、塩酸、硝酸、熱希硫酸、第二銅錯体と有機酸とを含有するエッチング液等が挙げられる。
また、イオンビームエッチング等による物理エッチングを用いてもよい。
なお、電解めっき膜、無電解めっき膜および金属層の材質等を考慮して、それぞれの除去に使用するエッチング液を使い分けてもよい。
【０１６３】
このような（ａ）〜（ｇ）の工程を経ることにより、基板上に下層導体回路（スルーホールを含む）を形成することができる。
また、第二の本発明の多層プリント配線板の製造方法では、無電解めっき膜を形成する前に、上記組成を有する無電解めっき用前処理液を用いて、基板に形成されたスルーホール用貫通孔の壁面等に前処理を施しているため、基板との密着性に優れた下層導体回路を形成することができる。
【０１６４】
また、第二の製造方法では、まず、上述した（ａ）〜（ｇ）の工程を経ることにより下層導体回路およびスルーホールが形成された基板を作成し、その後、第一の製造方法の（２）〜（１２）の工程と同様の方法を用いることにより、多層プリント配線板を製造することができる。
【０１６５】
次に、第三の本発明の多層プリント配線板の製造方法について説明する。
第三の本発明の多層プリント配線板の製造方法は、下層導体回路が形成された基板上に、層間樹脂絶縁層と上層導体回路とが順次積層され、これらの導体回路がバイアホールを介して接続されてなる多層プリント配線板の製造方法であって、少なくとも下記（Ａ）〜（Ｇ）の上層導体回路を形成する工程を含むことを特徴とする。
（Ａ）下層導体回路上または上層導体回路上に、樹脂層と金属層とからなる樹脂・金属層を形成する工程、
（Ｂ）上記樹脂・金属層を構成する樹脂層および金属層に、順次、開口形成処理を施し、バイアホール用開口を形成する工程、
（Ｃ）上記樹脂・金属層に、０．０１〜０．２５ｍｏｌ／ｌのアルカリ性化合物、および、０．１〜０．３ｍｏｌ／ｌの還元剤を含む水溶液からなる無電解めっき用前処理液を用いた前処理を施す工程、
（Ｄ）上記前処理が施された樹脂・金属層の表面に、無電解めっき膜を形成する工程、
（Ｅ）上記無電解めっき膜の一部にめっきレジストを形成する工程、
（Ｆ）上記めっきレジスト非形成部に電解めっき膜を形成する工程、および、
（Ｇ）上記めっきレジストを剥離した後、上記めっきレジスト下の無電解めっき膜と金属層とを除去する工程。
【０１６６】
第三の本発明の多層プリント配線板の製造方法によれば、層間樹脂絶縁層上に、バイアホールを含む上層導体回路を形成するための無電解めっき処理を施す前に、第一の本発明の多層プリント配線板の製造方法で用いる無電解めっき用前処理液と同様の前処理液を用いて、バイアホール用開口の壁面等に前処理を施すため、無電解めっき処理により層間樹脂絶縁層との密着性に優れた、均一な無電解めっき膜を形成することができ、その結果、接続信頼性、電気特性に優れる多層プリント配線板を製造することができる。
【０１６７】
第三の本発明の多層プリント配線板の製造方法（以下、単に第三の製造方法ともいう）は、第一の製造方法と比べて、（Ａ）〜（Ｇ）の工程が異なる。即ち、第一の製造方法は、基板上に下層導体回路を形成する工程に特徴を有するものであるのに対し、第三の製造方法は、層間樹脂絶縁層上に上層導体回路を形成する工程に特徴を有するものである。しかしながら、これら両者の製造方法においては、好適な形状、特性を有する導体回路を形成するにあたっての技術思想に大きな相違点はなく、特徴を有する製造工程が異なるのみである。
従って、以下の第三の製造方法の説明においては、製造工程については詳細に説明し、本製造方法における作用、効果等については簡単に説明することとする。
【０１６８】
第三の製造方法は、上記したように、（Ａ）〜（Ｇ）の工程、即ち、層間樹脂絶縁層上に上層導体回路を形成する工程に特徴を有するものであるため、まず、この（Ａ）〜（Ｇ）の工程について説明し、多層プリント配線板を製造する全製造工程については、後に説明することとする。
【０１６９】
第三の製造方法においては、（Ａ）〜（Ｇ）の工程を行うことにより、層間樹脂絶縁層上にスルーホールを含む上層導体回路を形成する。なお、層間樹脂絶縁層上に形成された上層導体回路上に、（Ａ）〜（Ｇ）の工程を行う場合には、複数の層間樹脂絶縁層と上層導体回路とが形成されることとなる。
第三の製造方法では、基板上に形成された下層導体回路上や層間樹脂絶縁層上に形成された上層導体回路上に樹脂層と金属層とからなる樹脂・金属層を形成する（工程（Ａ））。
上記樹脂・金属層の形成は、導体回路（下層導体回路または上層導体回路）上に樹脂を積層し、その後、金属を積層することにより行ってもよいし、樹脂と金属とを張り合わせた、いわゆる樹脂付き金属箔を形成した後、これを積層してもよい。
【０１７０】
導体回路上に樹脂を積層し、その後、金属を積層する場合には、まず、導体回路上に熱硬化性樹脂や樹脂複合体からなる未硬化の樹脂層を形成するか、または、熱可塑性樹脂からなる樹脂層を形成する。具体的には、第一の製造方法において説明した工程（４）と同様の方法を用いることができる。
また、熱硬化性樹脂や樹脂複合体、熱可塑性樹脂としては、第一の製造方法で用いたものと同様のものを用いることができる。
なお、上記熱硬化性樹脂や樹脂複合体からなる未硬化の樹脂層は、積層後、すぐに硬化させてもよいし、後述する工程で、金属層を形成した後に硬化させてもよい。
【０１７１】
次に、上記樹脂層上に金属層を形成する。
上記金属層の形成は、スパッタリングや真空蒸着法等の物理的蒸着法や、化学的蒸着法を用いて行うことができる。
また、上記金属層の材質としては、例えば、銅、ニッケル、アルミニウム、クロム、鉄、貴金属（金、銀、パラジウム、白金）等が挙げられ、その厚さは、０．１〜２．０μｍが望ましい。
なお、上記金属層は、一層からなるものであってもよいし、二層以上からなるものであってもよい。
また、無電解めっき処理により金属層を形成する場合には、無電解めっき処理を施す前に、後述する工程Ｃで用いる無電解めっき用前処理液を用いて、上記樹脂層に前処理を施してもよい。
【０１７２】
また、導体回路上に樹脂付き金属箔を積層する場合には、例えば、該樹脂付き金属箔を真空プレスすることにより、導体回路上に積層することができる。
このとき、真空プレスの条件としては特に限定されず、樹脂付き金属箔の材質、形状等を考慮して適宜選択すればよく、例えば、温度１５０〜１８０℃、圧力２〜４ＭＰａ、時間３０〜９０分、真空度１０ｋＰａ以下で行うことができる。
なお、上記樹脂付き金属箔の形成は、従来公知の方法により行うことができ、また、市販の樹脂付き金属箔を用いることもできる。
【０１７３】
次に、上記樹脂・金属層を構成する樹脂層および金属層に、順次、開口形成処理を施し、該開口形成処理により、バイアホール用開口を形成する（工程（Ｂ））。
即ち、まず、金属層に形成された金属層に開口を形成し、その後、上記金属層に形成された開口下の樹脂層に開口を形成し、バイアホール用開口とする。
【０１７４】
上記金属層に開口を形成する方法としては、例えば、以下の方法等を用いることができる。
即ち、金属層上の一部にエッチングレジストを形成した後、エッチングを行うことにより開口を形成することができる。
なお、エッチングレジストの形成やエッチング処理は、第一の製造方法における（ｂ）の工程で用いた方法と同様の方法を用いて行うことができる。
【０１７５】
また、この工程においては、金属層に開口を形成する前に、該金属層の厚さを０．５〜５μｍ程度に調整しておくことが望ましい。金属層の厚さが０．５μｍ未満では、後工程で基板に貫通孔を形成する際に、該金属層がコンフォーマルマスクとしての役割を果たすことができなくなることがあり、一方、金属層の厚さが５μｍを超えると、レーザ処理によりバイアホール用開口を形成する際に、該バイアホール用開口の形状が所望の形状にならないことがある。
なお、上記金属層の厚さの調整は、例えば、エッチング処理等により行うことができる。
【０１７６】
次に、上記エッチングレジストを除去し、開口を形成した金属層をコンフォーマルマスクとして、樹脂層に開口を形成し、バイアホール用開口とする。
上記開口の形成は、例えば、レーザ処理等により行うことができる。
このとき、使用するレーザとしては、例えば、炭酸ガスレーザ、エキシマレーザ、ＵＶレーザ、ＹＡＧレーザ等が挙げられる。
これらのレーザは、形成する開口の形状等を考慮して使い分けてもよい。
また、レーザ処理を行う際のビーム径は、形成する開口の径の１．３倍以上であることが望ましい。所望の形状の開口を形成することができるからである。
【０１７７】
上記レーザ処理後には、バイアホール用開口内の樹脂残渣を除去してもよい。
上記樹脂残渣の除去は、例えば、バイアホール用開口が形成された基板をクロム酸、過マンガン酸、カリウムの水溶液等に浸漬したり、Ｏ₂ プラズマ、ＣＦ₄ プラズマ、Ｏ₂ とＣＦ₄ との混合ガスのプラズマ等によるプラズマ処理により行うことができる。
【０１７８】
次に、上記樹脂・金属層に、０．０１〜０．２５ｍｏｌ／ｌのアルカリ性化合物、および、０．１〜０．３ｍｏｌ／ｌの還元剤を含む水溶液からなる無電解めっき用前処理液を用いた前処理を施す（工程（Ｃ））。
また、この前処理を施す前に、上記バイアホール用開口の形成された樹脂・金属層の表面には、予めパラジウム金属等の触媒を付与しておくことが望ましい。
なお、触媒の付与は、第一の製造方法と同様の方法等により行うことができる。
【０１７９】
この工程では、無電解めっき用前処理液として、第一の製造方法の（ｃ）の工程で用いた無電解めっき用前処理液と同様のものを用いる。
このような無電解めっき用前処理液を用いて、前処理を施すことにより、触媒を充分に活性化することができ、その結果、後工程で無電解めっき処理を施す際に、均一で、密着性に優れる無電解めっき膜を形成することができる。この理由は、第一の製造方法の説明で述べた通りである。
【０１８０】
上記前処理は、樹脂・金属層にバイアホール用開口が形成された基板を、上記無電解めっき用前処理液に浸漬することにより行う。
このときの前処理条件は、第一の製造方法で前処理を行う際の条件と同様の条件、即ち、上記無電解めっき用前処理液の温度が２０〜５０℃、前処理時間が０．５〜５分間であることが望ましい。
【０１８１】
次に、前処理が施された樹脂・金属層の表面、即ち、バイアホール用開口の壁面および基板上の金属層の表面に、無電解めっき膜を形成する（工程（Ｄ））。
上記無電解めっき膜の形成は、バイアホール用開口が形成された基板を無電解めっき液中に浸漬することにより行う。
【０１８２】
上記無電解めっき液としては特に限定されないが、第一の製造方法と同様のアルカリ性化合物、還元剤、銅イオン、および、酒石酸もしくはその塩を含む水溶液からなるものが好ましい。この理由は、第一の製造方法の説明で述べた通りである。
また、無電解めっきを行う条件も、第一の製造方法と同様の条件、即ち、上記無電解めっき液の温度が２５〜３５℃、浸漬時間が１０〜２０分間であることが望ましい。
【０１８３】
次に、上記工程（Ｄ）で形成した無電解めっき膜の一部、即ち、上層導体回路非形成部に相当する部分に、めっきレジストを形成する（工程（Ｅ））。
上記めっきレジストは、例えば、感光性ドライフィルムを張り付けたり、液状レジストを塗布した後、露光現像処理を施すことにより形成することができる。
【０１８４】
次に、上記めっきレジスト非形成部に電解めっき膜を形成する（工程（Ｆ））。
上記電解めっき膜を形成は、既に形成した無電解めっき膜をめっきリードとして行うことができる。
具体的には、例えば、硫酸、硫酸銅および添加剤を含む電解めっき液を用いることにより電解銅めっき膜を形成することができる。
【０１８５】
次に、上記めっきレジストを剥離し、その後、めっきレジスト下の無電解めっき膜と金属層とをエッチング処理により除去する（工程（Ｇ））。
上記エッチング処理は、第一の製造方法の（ｇ）の工程で用いるエッチング液と同様のものを用いて行うことができる。
【０１８６】
このような（Ａ）〜（Ｇ）の工程を経ることにより、下層導体回路または上層導体回路上に、層間樹脂絶縁層と上層導体回路（バイアホールを含む）とを積層形成することができる。
また、第三の本発明の多層プリント配線板の製造方法では、無電解めっき膜を形成する前に、上記組成を有する無電解めっき用前処理液を用いて、バイアホール用開口の壁面や金属層の表面等に前処理を施しているため、層間樹脂絶縁層との密着性に優れた上層導体回路（バイアホールを含む）を形成することができる。
【０１８７】
次に、第三の製造方法の全製造工程について、工程順に説明する。
（１）第三の製造方法においては、まず、絶縁性基板の表面に下層導体回路が形成された基板を作製する。
上記絶縁性基板としては、樹脂基板が望ましく、具体的には、ガラスエポキシ基板、ポリエステル基板、ポリイミド基板、ビスマレイミド−トリアジン樹脂基板、熱硬化性ポリフェニレンエーテル基板、フッ素樹脂基板、銅張積層板、ＲＣＣ基板等が挙げられる。
このとき、必要に応じて、絶縁性基板に貫通孔を設けてもよい。この場合、貫通孔は直径１００〜３００μｍのドリル、レーザ光等を用いて形成することが望ましい。
【０１８８】
（２）次に、無電解めっきを施した後、基板上に下層導体回路形状のエッチングレジストを形成し、エッチングを行うことにより下層導体回路を形成する。無電解めっきとしては銅めっきが望ましい。また、絶縁性基板に貫通孔を設けた場合には、該貫通孔の壁面にも同時に無電解めっきを施してスルーホールを形成することにより、基板の両面の下層導体回路間を電気的に接続してもよい。
なお、絶縁性基板に無電解めっきを施す場合には、上述した無電解めっき用前処理液を用いて、絶縁性基板表面に前処理を施しておくことが望ましい。
また、第一または第二の製造方法の（ａ）〜（ｇ）の工程を経ることにより製造された下層導体回路（スルーホールを含む）の形成された基板を用いてもよい。
【０１８９】
（３）次に、必要に応じて、スルーホールの内壁および下層導体回路の表面の粗化処理を行う。粗化処理方法としては、例えば、黒化（酸化）−還元処理、エッチング処理、Ｃｕ−Ｎｉ−Ｐ針状合金めっきによる処理などが挙げられる。
【０１９０】
上記黒化（酸化）−還元処理の具体的な方法としては、ＮａＯＨ（１０〜２０ｇ／ｌ）、ＮａＣｌＯ₂ （４０〜５０ｇ／ｌ）、Ｎａ₃ ＰＯ₄ （６〜１５ｇ／ｌ）を含む水溶液を黒化浴（酸化浴）とする黒化処理、および、ＮａＯＨ（２．７〜１０ｇ／ｌ）、ＮａＢＨ₄ （１．０〜６．０ｇ／ｌ）を含む水溶液を還元浴とする還元処理を行う方法等が挙げられる。
【０１９１】
上記エッチング処理に用いるエッチング液としては、有機酸と第二銅錯体との混合溶液が望ましい。上記有機酸としては、例えば、蟻酸、酢酸、プロピオン酸、酪酸、吉草酸、カプロン酸、アクリル酸、クロトン酸、シュウ酸、マロン酸、コハク酸、グルタル酸、マレイン酸、安息香酸、グリコール酸、乳酸、リンゴ酸、スルファミン酸等が挙げられる。これらは、単独で用いてもよく、２種以上併用してもよい。上記エッチング液において、上記有機酸の含有量は、０．１〜３０重量％が望ましい。酸化された銅の溶解性を維持し、かつ、触媒安定性を確保することができるからである。
【０１９２】
上記第二銅錯体としては、アゾール類の第二銅錯体が望ましい。このアゾール類の第二銅錯体は、金属銅等を酸化する酸化剤として作用する。アゾール類としては、例えば、ジアゾール、トリアゾール、テトラゾール等が挙げられる。これらのなかでも、イミダゾール、２−メチルイミダゾール、２−エチルイミダゾール、２−エチル−４−メチルイミダゾール、２−フェニルイミダゾール、２−ウンデシルイミダゾールが望ましい。上記エッチング液において、上記第二銅錯体の含有量は、１〜１５重量％が望ましい。溶解性および安定性に優れ、また、触媒核を構成するパラジウム等の貴金属をも溶解させることができるからである。
【０１９３】
上記めっき処理としては、例えば、硫酸銅（１〜４０ｇ／ｌ）、硫酸ニッケル（０．１〜６．０ｇ／ｌ）、クエン酸（１０〜２０ｇ／ｌ）、次亜リン酸ナトリウム（１０〜１００ｇ／ｌ）、ホウ酸（１０〜４０ｇ／ｌ）および界面活性剤（日信化学工業社製、サーフィノール４６５）（０．０１〜１０ｇ／ｌ）を含むｐＨ＝９の無電解めっき浴にて無電解めっきを施し、Ｃｕ−Ｎｉ−Ｐ合金からなる粗化層を形成する方法等が挙げられる。
この範囲で析出するめっき被膜の結晶構造は、針状構造となるため、アンカー効果に優れるからである。上記無電解めっき浴には、上記化合物に加えて錯化剤や添加剤を加えてもよい。
【０１９４】
（４）次に、樹脂充填材をスルーホールに充填する。また、必要に応じて、絶縁性基板表面の下層導体回路が形成されていない凹部に樹脂充填材を充填し、その後、研磨等を行って絶縁性基板表面を平坦化してもよい。
この後、上記樹脂充填材を、例えば、１００℃／２０分の条件で乾燥させた後、硬化させる。
硬化は、温度５０〜２５０℃の間で行うのが望ましい。その硬化条件の一例としては、１００℃で１時間加熱した後、１５０℃で１時間加熱する方法が挙げられる。必要に応じて、順次低い温度から高い温度と温度を変化させて硬化させるステップ硬化を行ってもよい。
【０１９５】
また、研磨を行って下層導体回路表面を含む絶縁性基板表面を平坦化した場合には、必要に応じて、もう一度、下層導体回路の粗化処理を行ってもよい。粗化処理方法としては、例えば、黒化（酸化）−還元処理、エッチング処理、Ｃｕ−Ｎｉ−Ｐ合金めっきによる処理等が挙げられる。
【０１９６】
（５）次に、上記した（Ａ）〜（Ｇ）の工程を行うことより、表面に下層導体回路が形成された基板上に層間樹脂絶縁層と上層導体回路とを形成する。
（６）次に、必要により、上記（３）に記載した方法と同様の方法で上層導体回路の粗化処理を行った後、上記（Ａ）〜（Ｇ）の工程を繰り返すことにより、下層導体回路が形成された基板上に、上層導体回路と層間樹脂絶縁とが順次積層された基板を製造することができる。
【０１９７】
（７）次に、最上層の上層導体回路を含む基板面にソルダーレジスト層を形成し、さらに、該ソルダーレジスト層を開口して半田パッドを形成した後、上記半田パッドに半田ペーストを充填し、リフローすることにより半田バンプを形成する。その後、外部基板接続面に、ピンを配設したり、半田ボールを形成したりすることにより、ＰＧＡ(Pin Grid Array)やＢＧＡ(Ball Grid Array) とする。
なお、ソルダーレジスト層や半田バンプの形成は、第一の製造方法で用いた方法と同様の方法により行うことができる。
【０１９８】
次に、第四の本発明の多層プリント配線板の製造方法について説明する。
第四の本発明の多層プリント配線板の製造方法は、下層導体回路が形成された基板上に、層間樹脂絶縁層と上層導体回路とが順次積層され、これらの導体回路がバイアホールを介して接続されてなる多層プリント配線板の製造方法であって、少なくとも下記（Ａ）〜（Ｇ）の上層導体回路を形成する工程を含むことを特徴とする。
（Ａ）下層導体回路上または上層導体回路上に、樹脂層と金属層とからなる樹脂・金属層を形成する工程、
（Ｂ）上記樹脂・金属層を構成する樹脂層および金属層に、順次、開口形成処理を施し、該開口形成処理によりバイアホール用開口を形成する工程、
（Ｃ）上記樹脂・金属層に、０．０１〜０．２５ｍｏｌ／ｌのアルカリ性化合物、および、０．１〜０．３ｍｏｌ／ｌの還元剤を含む水溶液からなる無電解めっき用前処理液を用いた前処理を施す工程、
（Ｄ）上記前処理の施された樹脂・金属層の表面に、無電解めっき膜を形成する工程、
（Ｅ）上記無電解めっき膜上に電解めっき膜を形成する工程、
（Ｆ）上記電解めっき膜上の一部に、エッチングレジストを形成する工程、および、
（Ｇ）上記エッチングレジストを非形成部下の電解めっき膜と無電解めっき膜と金属層とをエッチング処理により除去する工程。
【０１９９】
第四の本発明の多層プリント配線板の製造方法によれば、層間樹脂絶縁層上に、バイアホールを含む上層導体回路を形成するための無電解めっき処理を施す前に、第一の本発明の多層プリント配線板の製造方法で用いる無電解めっき用前処理液と同様の前処理液を用いて、バイアホール用開口の壁面等に前処理を施すため、無電解めっき処理により層間樹脂絶縁層との密着性に優れた、均一な無電解めっき膜を形成することができ、その結果、接続信頼性、電気特性に優れる多層プリント配線板を製造することができる。
【０２００】
第四の本発明の多層プリント配線板の製造方法（以下、単に第四の製造方法ともいう）は、第三の製造方法と比べて、（Ｄ）〜（Ｇ）の工程、即ち、バイアホール用開口の内壁面を含む樹脂・金属層の表面に無電解めっき膜を形成した後、電解めっき処理等を経て層間樹脂絶縁層上に上層導体回路を形成する工程のみが異なる。従って、第四の製造方法については、この（Ｄ）〜（Ｇ）の工程についてのみ詳細に説明することとし、これ以外の製造工程については、簡単に説明することとする。
【０２０１】
まず、第四の製造方法における（Ａ）〜（Ｇ）の工程について説明する。
第四の製造方法においては、第三の製造方法における（Ａ）〜（Ｄ）の工程と同様して、バイアホール用開口の内壁面を含む樹脂・金属層の表面に、無電解めっき膜を形成する（工程（Ａ）〜（Ｄ））。
【０２０２】
次に、上記（Ａ）〜（Ｄ）工程で形成した無電解めっき膜上に電解めっき膜を形成する（工程（Ｅ））。
上記電解めっき膜の形成は、既に形成した無電解めっき膜をめっきリードとして行うことができる。
具体的には、例えば、硫酸、硫酸銅および添加剤を含む電解めっき液を用いることにより電解銅めっき膜を形成することができる。
【０２０３】
次に、電解めっき膜の一部、即ち、上層導体回路形成部分に相当する部分にエッチングレジストを形成する（工程（Ｆ））。
上記エッチングレジストは、例えば、感光性ドライフィルムを張り付けたり、液状レジストを塗布した後、露光現像処理を施すことにより形成することができる。
【０２０４】
次に、エッチング処理を施すことにより、上記エッチングレジスト非形成部下の電解めっき膜、無電解めっき膜および金属層を除去する（工程（Ｇ））。その後、上記エッチングレジストを強アルカリ水溶液等を用いて除去する。
上記エッチング処理は、第二の製造方法における（ｇ）の工程で用いた方法と同様の方法を用いて行うことができる。
【０２０５】
このような（Ａ）〜（Ｇ）の工程を経ることにより、下層導体回路または上層導体回路上に、層間樹脂絶縁層と上層導体回路（バイアホールを含む）とを積層形成することができる。
また、第四の本発明の多層プリント配線板の製造方法では、無電解めっき膜を形成する前に、上記組成を有する無電解めっき用前処理液を用いて、バイアホール用開口の壁面等に前処理を施しているため、層間樹脂絶縁層との密着性に優れた上層導体回路を形成することができる。
【０２０６】
このように、第一〜第四の本発明の多層プリント配線板の製造方法では、接続信頼性および電気特性に優れた多層プリント配線板を製造することができる。
ここで、第一および第二の本発明の多層プリント配線板の製造方法は、基板上に下層導体回路を形成する工程に特徴を有するものであり、第三および第四の多層プリント配線板の製造方法は、層間樹脂絶縁層上に上層導体回路を形成する工程に特徴を有するものである。従って、第一および第二の本発明の多層プリント配線板の製造方法のいずれかと、第三および第四の本発明の多層プリント配線板の製造方法のいずれかとを組み合わせることにより、より接続信頼性および電気特性に優れた多層プリント配線板を製造することができる。
【０２０７】
【実施例】
以下、本発明をさらに詳細に説明する。
（実施例１）
Ａ．樹脂充填材の調製
ビスフェノールＦ型エポキシモノマー（油化シェル社製、分子量：３１０、ＹＬ９８３Ｕ）１００重量部、表面にシランカップリング剤がコーティングされた平均粒径が１．６μｍで、最大粒子の直径が１５μｍ以下のＳｉＯ₂ 球状粒子（アドテック社製、ＣＲＳ １１０１−ＣＥ）１７０重量部およびレベリング剤（サンノプコ社製 ペレノールＳ４）１．５重量部を容器にとり、攪拌混合することにより、その粘度が２３±１℃で４５〜４９Ｐａ・ｓの樹脂充填材を調製した。なお、硬化剤として、イミダゾール硬化剤（四国化成社製、２Ｅ４ＭＺ−ＣＮ）６．５重量部を用いた。
【０２０８】
Ｂ．多層プリント配線板の製造
（１）厚さ０．８ｍｍのガラスエポキシ樹脂またはＢＴ（ビスマレイミドトリアジン）樹脂からなる絶縁性基板３０の両面に１８μｍの銅箔３２がラミネートされている銅張積層板３０Ａを出発材料とした（図１（ａ）参照）。まず、この銅張積層板３０Ａをドリル削孔し、無電解めっき処理を施し、パターン状にエッチングすることにより、基板３０の両面に下層導体回路３４とスルーホール３６を形成した（図１（ｂ）参照）。
【０２０９】
（２）スルーホール３６および下層導体回路３４を形成した基板を水洗いし、乾燥した後、ＮａＯＨ（１０ｇ／ｌ）、ＮａＣｌＯ₂ （４０ｇ／ｌ）、Ｎａ₃ ＰＯ₄ （６ｇ／ｌ）を含む水溶液を黒化浴（酸化浴）とする黒化処理、および、ＮａＯＨ（１０ｇ／ｌ）、ＮａＢＨ₄ （６ｇ／ｌ）を含む水溶液を還元浴とする還元処理を行い、そのスルーホール３６を含む下層導体回路３４の全表面に粗化面３８を形成した（図１（ｃ）参照）。
【０２１０】
（３）上記Ａに記載した樹脂充填材を調製した後、下記の方法により調製後２４時間以内に、スルーホール３６内、および、基板３０の片面の下層導体回路非形成部と下層導体回路３４の外縁部とに樹脂充填材４０の層を形成した。
すなわち、まず、スキージを用いてスルーホール内に樹脂充填材を押し込んだ後、１００℃、２０分の条件で乾燥させた。次に、下層導体回路非形成部に相当する部分が開口したマスクを基板上に載置し、スキージを用いて凹部となっている下層導体回路非形成部に樹脂充填材４０の層を形成し、１００℃、２０分の条件で乾燥させた（図１（ｄ）参照）。
【０２１１】
（４）上記（３）の処理を終えた基板の片面を、＃６００のベルト研磨紙（三共理化学製）を用いたベルトサンダー研磨により、下層導体回路の３４の表面やスルーホール３６のランド３６ａ表面に樹脂充填材４０が残らないように研磨し、次いで、上記ベルトサンダー研磨による傷を取り除くためのバフ研磨を行った。
このような一連の研磨を基板の他方の面についても同様に行った。
次いで、１００℃で１時間、１５０℃で１時間の加熱処理を行って樹脂充填材４０を硬化した。
【０２１２】
このようにして、スルーホール３６や下層導体回路非形成部に形成された樹脂充填材４０の表層部および下層導体回路３４の表面を平坦化し、樹脂充填材４０と下層導体回路３４の側面とが粗化面３８を介して強固に密着し、またスルーホール３６の内壁面と樹脂充填材４０とが粗化面３８を介して強固に密着した基板を得た（図２（ａ）参照）。即ち、この工程により、樹脂充填材４０の表面と下層導体回路３４の表面とが同一平面となる。
【０２１３】
（５）上記基板を水洗、アルカリ脱脂した後、ソフトエッチングし、次いで、エッチング液を基板の両面にスプレイで吹きつけて、下層導体回路３４の表面とスルーホール３６のランド表面３６ａとをエッチングすることにより、下層導体回路３４の全表面に粗化面４２を形成した（図２（ｂ）参照）。
エッチング液としては、イミダゾール銅（ＩＩ）錯体１０重量部、グリコール酸７重量部、塩化カリウム５重量部からなるエッチング液（メック社製、メックエッチボンド）を使用した。
【０２１４】
（６）基板の両面に、樹脂付き銅箔（日立化成工業社製 ＭＣＦ−６０００Ｅ、樹脂２０の厚さが６０μｍ、銅箔２２の厚さが１２μｍ）２０Ａを、載置した後、真空プレスすることにより圧着した（図２（ｃ）参照）。
ここで、真空プレスは、１７５℃、９０ｍｉｎ、圧力３ＭＰａ、真空度＜６．５ｋＰａの条件で行った。
【０２１５】
（７）次に、圧着した樹脂付き銅箔２０Ａの表面の銅箔２２を、エッチング液（三菱瓦斯化学社製 ＳＥ−０７）を用いて、その厚さが３μｍとなるまで全面エッチングした（図２（ｄ）参照）。
【０２１６】
（８）次に、銅箔２２上に、ドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５）を張り付け、マスクを載置して、１００ｍＪ／ｃｍ² で露光、０．８％炭酸ナトリウムで現像処理し、バイアホール用開口形成部に開口４３ａを有するエッチングレジスト４３を形成した（図３（ａ）参照）。
【０２１７】
（９）次に、開口４３ａ下の銅箔２２を塩化第二銅溶液からなるエッチング液にて除去し（図３（ｂ）参照）、その後、エッチングレジスト４３を水酸化ナトリウム水溶液で剥離し、開口２２ａを有し、コンフォーマルマスクとなる銅箔２２を形成した（図３（ｃ）参照）。
【０２１８】
（１０）次に、炭酸ガスレーザ照射装置（三菱電気社製 ６０５ＧＴＸ）を用いて、銅箔の開口２２ａ毎に２ショットの短パルスのレーザを照射し、樹脂付き銅箔２０Ａの樹脂２０に直径６０μｍの開口を形成し、バイアホール用開口２０ａを設けた（図３（ｄ）参照）。この後、酸素プラズマを用いてデスミア処理を行った。
【０２１９】
（９）次に、バイアホール用開口２０ａを形成した基板の表面に、パラジウム触媒を付与することにより、銅箔２２の表面およびバイアホール用開口２０ａの内壁面に触媒核を付着させた（図示せず）。すなわち、上記基板を塩化パラジウム（ＰｂＣｌ₂ ）と塩化第一スズ（ＳｎＣｌ₂ ）とを含む触媒液中に浸漬し、パラジウム金属を析出させることにより触媒を付与した。
【０２２０】
（１０）次に、以下の組成の無電解めっき用前処理液中に基板を浸漬することにより前処理を施した。
〔無電解めっき用前処理液〕
ＮａＯＨ ０．１０ｍｏｌ／ｌ
ＨＣＨＯ ０．１０ｍｏｌ／ｌ
〔前処理条件〕
３０℃の液温度で３分
【０２２１】
（１１）次に、以下の組成の無電解銅めっき水溶液中に、前処理を施した基板を浸漬して、バイアホール用開口２０ａの内壁面を含む基板表面全体に厚さ０．６〜３．０μｍの無電解銅めっき膜５２を形成した（図４（ａ）参照）。
〔無電解めっき水溶液〕
ＮｉＳＯ₄ ０．００３ ｍｏｌ／ｌ
酒石酸 ０．２００ ｍｏｌ／ｌ
硫酸銅 ０．０３０ ｍｏｌ／ｌ
ＨＣＨＯ ０．０５０ ｍｏｌ／ｌ
ＮａＯＨ ０．１００ ｍｏｌ／ｌ
α、α′−ビピリジル １００ ｍｇ／ｌ
ポリエチレングリコール（ＰＥＧ） ０．１０ ｇ／ｌ
〔無電解めっき条件〕
３４℃の液温度で４０分
【０２２２】
（１２）無電解銅めっき膜５２が形成された基板にドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５）を張り付け、所定位置にパターンの形成されたマスク（図示せず）を載置して、１００ｍＪ／ｃｍ² で露光した。その後、０．８％炭酸ナトリウムで現像処理し、バイアホール形成部および上層導体回路形成部に開口５４ａを有するめっきレジスト５４を設けた（図４（ｂ）参照）。
【０２２３】
（１３）ついで、基板を５０℃の水で洗浄して脱脂し、２５℃の水で水洗後、さらに硫酸で洗浄してから、以下の条件で電解めっきを施し、めっきレジスト非形成部５４ａに、厚さ２０μｍの電解銅めっき膜５６を形成した（図４（ｃ）参照）。
〔電解めっき液〕
硫酸 ２．２４ ｍｏｌ／ｌ
硫酸銅 ０．２６ ｍｏｌ／ｌ
添加剤 １９．５ ｍｌ／ｌ
（アトテックジャパン社製、カパラシドＧＬ）
〔電解めっき条件〕
電流密度 １ Ａ／ｄｍ²
時間 ６５ 分
温度 ２２±２ ℃
【０２２４】
（１４）さらに、めっきレジスト５４を５％ＫＯＨで剥離除去した後、そのめっきレジスト５４下の無電解めっき膜５２および銅箔２２を硫酸と過酸化水素との混合液でエッチング処理して溶解除去し、厚さ１８μｍの独立した上層導体回路５８（バイアホール６０を含む）とした（図４（ｄ）参照）。
【０２２５】
（１５）ついで、上記（５）と同様の処理を行い、上層導体回路５８（バイアホール６０を含む）表面に粗化面６２を形成した（図５（ａ）参照）。
（１６）上記（６）〜（１５）の工程を繰り返すことにより、さらに上層導体回路８８（バイアホール９０を含む）と層間樹脂絶縁層１２０とを形成し、多層配線板を得た（図５（ｂ）参照）。
【０２２６】
（１７）次に、ジエチレングリコールジメチルエーテル（ＤＭＤＧ）に６０重量％の濃度になるように溶解させた、クレゾールノボラック型エポキシ樹脂（日本化薬社製）のエポキシ基５０％をアクリル化した感光性付与のオリゴマー（分子量：４０００）４６．６７重量部、メチルエチルケトンに溶解させた８０重量％のビスフェノールＡ型エポキシ樹脂（油化シェル社製、商品名：エピコート１００１）１５．０重量部、イミダゾール硬化剤（四国化成社製、商品名：２Ｅ４ＭＺ−ＣＮ）１．６重量部、感光性モノマーである２官能アクリルモノマー（日本化薬社製、商品名：Ｒ６０４）４．５重量部、同じく多価アクリルモノマー（共栄化学社製、商品名：ＤＰＥ６Ａ）１．５重量部、分散系消泡剤（サンノプコ社製、Ｓ−６５）０．７１重量部を容器にとり、攪拌、混合して混合組成物を調製し、この混合組成物に対して光重合開始剤としてベンゾフェノン（関東化学社製）２．０重量部、光増感剤としてのミヒラーケトン（関東化学社製）０．２重量部、を加えることにより、粘度を２５℃で２．０Ｐａ・ｓに調整したソルダーレジスト組成物を得た。
なお、粘度測定は、Ｂ型粘度計（東京計器社製、ＤＶＬ−Ｂ型）で６０ｒｐｍの場合はローターＮｏ．４、６ｒｐｍの場合はローターＮｏ．３によった。
【０２２７】
（１８）次に、多層配線板の両面に、上記ソルダーレジスト組成物を２０μｍの厚さで塗布し、７０℃で２０分間、７０℃で３０分間の条件で乾燥処理を行った後、ソルダーレジスト開口部のパターンが描画された厚さ５ｍｍのフォトマスクをソルダーレジスト層に密着させて１０００ｍＪ／ｃｍ² の紫外線で露光し、ＤＭＴＧ溶液で現像処理し、２００μｍの直径の開口を形成した。
そして、さらに、８０℃で１時間、１００℃で１時間、１２０℃で１時間、１５０℃で３時間の条件でそれぞれ加熱処理を行ってソルダーレジスト層を硬化させ、開口を有し、その厚さが２０μｍのソルダーレジストパターン層を形成した。上記ソルダーレジスト組成物としては、市販のソルダーレジスト組成物を使用することもできる。
【０２２８】
（１９）次に、ソルダーレジスト層９３を形成した基板を、塩化ニッケル（２．３×１０^-1ｍｏｌ／ｌ）、次亜リン酸ナトリウム（２．８×１０^-1ｍｏｌ／ｌ）、クエン酸ナトリウム（１．６×１０^-1ｍｏｌ／ｌ）を含むｐＨ＝４．５の無電解ニッケルめっき液に２０分間浸漬して、開口部に厚さ５μｍのニッケルめっき層９５を形成した。さらに、その基板をシアン化金カリウム（７．６×１０^-3ｍｏｌ／ｌ）、塩化アンモニウム（１．９×１０^-1ｍｏｌ／ｌ）、クエン酸ナトリウム（１．２×１０^-1ｍｏｌ／ｌ）、次亜リン酸ナトリウム（１．７×１０^-1ｍｏｌ／ｌ）を含む無電解金めっき液に８０℃の条件で７．５分間浸漬して、ニッケルめっき層９５上に、厚さ０．０３μｍの金めっき層９６を形成した。
【０２２９】
（２０）この後、基板のＩＣチップを載置する面のソルダーレジスト層の開口に、スズ−鉛を含有するはんだペーストを印刷し、さらに他方の面のソルダーレジスト層９３の開口にスズ−アンチモンを含有するはんだペーストを印刷した後、２００℃でリフローすることによりはんだバンプ（はんだ体）９７を形成し、はんだバンプ９７を有する多層プリント配線板を製造した（図６参照）。
【０２３０】
（実施例２）
実施例１における（１２）〜（１４）の工程に代えて、下記（１）〜（３）の工程を行うことにより多層プリント配線板を製造した以外は、実施例１と同様にして多層プリント配線板を製造した。
【０２３１】
（１）無電解めっき膜５２が形成された基板（図７（ａ）参照）に、以下の条件で電解めっきを施し、厚さ２０μｍの電解銅めっき膜５６を形成した（図７（ｂ）参照）。
〔電解めっき液〕
硫酸 ２．２４ ｍｏｌ／ｌ
硫酸銅 ０．２６ ｍｏｌ／ｌ
添加剤 １９．５ ｍｌ／ｌ
（アトテックジャパン社製、カパラシドＧＬ）
〔電解めっき条件〕
電流密度 １ Ａ／ｄｍ²
時間 ６５ 分
温度 ２２±２ ℃
【０２３２】
（２）次に、電解銅めっき膜５６が形成された基板に、ドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５）を張り付け、所定位置にパターンの形成されたマスク（図示せず）を載置して、１００ｍＪ／ｃｍ² で露光した。その後、０．８％炭酸ナトリウムで現像処理し、バイアホール形成部および上層導体回路形成部を覆うＬ／Ｓ：３０μｍ／３０μｍのエッチングレジスト５５を設けた（図７（ｃ）参照）。
【０２３３】
（３）さらに、塩化第二銅溶液からなるエッチング液を用いてパターンエッチングを行うことにより、エッチングレジスト５５非形成部下の電解銅めっき膜５６、無電解銅めっき膜５２および銅箔２２を除去し、その後、２％水酸化ナトリウム水溶液によりエッチングレジスト５５を剥離し、厚さ１８μｍの独立した上層導体回路５８（バイアホール６０を含む）とした（図７（ｄ）参照）。
【０２３４】
（実施例３）
無電解めっき用前処理液におけるＮａＯＨの濃度を、０．０２５ｍｏｌ／ｌにした以外は、実施例１と同様にして多層プリント配線板を製造した。
【０２３５】
（実施例４）
無電解めっき用前処理液におけるＨＣＨＯの濃度を、０．１０ｍｏｌ／ｌにした以外は、実施例１と同様にして多層プリント配線板を製造した。
【０２３６】
（実施例５）
無電解めっき液において、ＮｉＳＯ₄ の代わりに、ＣｏＳＯ₄ （濃度：０．００２ｍｏｌ／ｌを用いた以外は、実施例１と同様にして多層プリント配線板を製造した。
【０２３７】
（実施例６）
実施例１の（１）の工程に代えて、下記（１）〜（１０）の工程を行うことにより、下層導体回路１３４とスルーホール１３６とが形成された基板１３０を作製した以外は、実施例１と同様にして多層プリント配線板を製造した。
【０２３８】
（１）厚さ０．８ｍｍのガラスエポキシ樹脂またはＢＴ（ビスマレイミド−トリアジン）樹脂からなる基板１３０の両面に１８μｍの銅箔１３２がラミネートされている銅張積層板１３０Ａを出発材料とし、まず、銅張積層板１３０Ａの表面の銅箔１３２を、エッチング液（三菱瓦斯化学社製 ＳＥ−０７）を用いて、その厚さが３μｍとなるまで全面エッチングした（図８（ａ）参照）。
【０２３９】
（２）次に、銅箔１３２上に、ドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５）を張り付け、マスクを載置して１００ｍＪ／ｃｍ² で露光、０．８％炭酸ナトリウムで現像処理し、スルーホール用貫通孔形成部に開口１３３ａを有するエッチングレジスト１３３を形成した（図８（ｂ）参照）。
【０２４０】
（３）次に、開口１３３ａ下の銅箔１３２を塩化第二銅溶液からなるエッチング液にて除去し、その後、エッチングレジスト１３３を水酸化ナトリウム水溶液で剥離し、スルーホール用貫通孔形成部に開口１３２ａを有し、コンフォーマルマスクとなる銅箔１３２を形成した（図８（ｃ）参照）。
【０２４１】
（４）次に、炭酸ガスレーザ照射装置（三菱電気社製 ６０５ＧＴＸ）を用いて、銅箔の開口１３２ａ毎に５ショットの短パルスのレーザを照射し、基板１３０に開口１３０ａを形成した（図８（ｄ）参照）。この後、酸素プラズマを用いてデスミア処理を行った。
【０２４２】
（５）次に、スルーホール用貫通孔１３５を形成した基板の表面に、パラジウム触媒を付与することにより、銅箔１３２の表面およびスルーホール用貫通孔の内壁面に触媒核を付着させた（図示せず）。すなわち、スルーホール用貫通孔の形成された基板１３０Ａを塩化パラジウム（ＰｄＣｌ₂ ）と塩化第一スズ（ＳｎＣｌ₂ ）とを含む触媒液中に浸漬し、パラジウム金属を析出させることにより触媒を付与した。
【０２４３】
（６）次に、以下の組成の無電解めっき用前処理液中に基板を浸漬することにより前処理を施した。
〔無電解めっき用前処理液〕
ＮａＯＨ ０．１０ｍｏｌ／ｌ
ＨＣＨＯ ０．１０ｍｏｌ／ｌ
〔前処理条件〕
３０℃の液温度で３分
【０２４４】
（７）次に、以下の組成の無電解銅めっき水溶液中に、前処理を施した基板を浸漬して、スルーホール用貫通孔１３５の内壁面を含む基板表面全体に厚さ０．６〜３．０μｍの無電解銅めっき膜１４２を形成した（図９（ａ）参照）。 〔無電解めっき水溶液〕
ＮｉＳＯ₄ ０．００３ ｍｏｌ／ｌ
酒石酸 ０．２００ ｍｏｌ／ｌ
硫酸銅 ０．０３０ ｍｏｌ／ｌ
ＨＣＨＯ ０．０５０ ｍｏｌ／ｌ
ＮａＯＨ ０．１００ ｍｏｌ／ｌ
α、α′−ビピリジル １００ ｍｇ／ｌ
ＰＥＧ ０．１０ ｇ／ｌ
〔無電解めっき条件〕
３４℃の液温度で４０分
【０２４５】
（８）無電解銅めっき膜１４２が形成された基板にドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５社製）を張り付け、所定位置にパターンの形成されたマスク（図示せず）を載置して、１００ｍＪ／ｃｍ² で露光した。その後、０．８％炭酸ナトリウムで現像処理し、スルーホール形成部および下層導体回路形成部に開口を有するめっきレジスト１４４を形成した。
【０２４６】
（９）さらに、基板を５０℃の水で洗浄して脱脂し、２５℃の水で水洗後、さらに硫酸で洗浄してから、以下の条件で電解めっきを施し、めっきレジスト非形成部に、厚さ２０μｍの電解銅めっき膜１４６を形成した（図９（ｂ）参照）。
〔電解めっき液〕
硫酸 ２．２４ ｍｏｌ／ｌ
硫酸銅 ０．２６ ｍｏｌ／ｌ
添加剤 １９．５ ｍｌ／ｌ
（アトテックジャパン社製、カパラシドＧＬ）
〔電解めっき条件〕
電流密度 １ Ａ／ｄｍ²
時間 ６５ 分
温度 ２２±２ ℃
【０２４７】
（１０）次に、めっきレジスト１４４を５％ＫＯＨで剥離除去した後、めっきレジスト１４４下の無電解めっき膜１４２および銅箔１３２を硫酸と過酸化水素との混合液でエッチング処理して溶解除去し、独立した下層導体回路１３４とスルーホール１３６とが形成された基板１３０を作製した（図９（ｃ）参照）。
【０２４８】
（実施例７）
実施例１の（１）の工程に代えて、下記（１）〜（４）の工程を行うことにより、下層導体回路１３４とスルーホール１３６とが形成された基板１３０を作製した以外は、実施例１と同様にして多層プリント配線板を製造した。
【０２４９】
（１）まず、実施例６の（１）〜（７）と同様にしてスルーホール用貫通孔１３５の内壁面を含む表面全体に厚さ０．６〜３．０μｍの無電解銅めっき膜１４２が形成された基板を製造した（図１０（ａ）参照）。
【０２５０】
（２）無電解銅めっき膜１４２が形成された基板に、以下の条件で電解めっきを施し、厚さ２０μｍの電解銅めっき膜１４７を形成した（図１０（ｂ）参照）。〔電解めっき液〕
硫酸 ２．２４ ｍｏｌ／ｌ
硫酸銅 ０．２６ ｍｏｌ／ｌ
添加剤 １９．５ ｍｌ／ｌ
（アトテックジャパン社製 カパラシドＧＬ）
〔電解めっき条件〕
電流密度 １ Ａ／ｄｍ²
時間 ６５ 分
温度 ２２±２ ℃
【０２５１】
（３）次に、電解銅めっき膜１４７が形成された基板にドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５社製）を張り付け、所定位置にパターンの形成されたマスク（図示せず）を載置して、１００ｍＪ／ｃｍ² で露光した。その後、０．８％炭酸ナトリウムで現像処理し、スルーホール形成部および下層導体回路形成部を覆うエッチングレジスト１４９を形成した（図１０（ｃ）参照）。
【０２５２】
（４）さらに、塩化第二銅溶液からなるエッチング液を用いてパターンエッチングを行い、その後、２％水酸化ナトリウム水溶液によりエッチングレジスト１４９を剥離し、独立した下層導体回路１３４とスルーホール１３６とが形成された基板１３０を作製した（図１０（ｄ）参照）。
【０２５３】
（実施例８）
Ａ．層間樹脂絶縁層用の樹脂フィルムの作製
ビスフェノールＡ型エポキシ樹脂（エポキシ当量４６９、油化シェルエポキシ社製エピコート１００１）３０重量部、クレゾールノボラック型エポキシ樹脂（エポキシ当量２１５、大日本インキ化学工業社製 エピクロンＮ−６７３）４０重量部、トリアジン構造含有フェノールノボラック樹脂（フェノール性水酸基当量１２０、大日本インキ化学工業社製 フェノライトＫＡ−７０５２）３０重量部をエチルジグリコールアセテート２０重量部、ソルベントナフサ２０重量部に攪拌しながら加熱溶解させ、そこへ末端エポキシ化ポリブタジエンゴム（ナガセ化成工業社製 デナレックスＲ−４５ＥＰＴ）１５重量部と２−フェニル−４、５−ビス（ヒドロキシメチル）イミダゾール粉砕品１．５重量部、微粉砕シリカ２重量部、シリコン系消泡剤０．５重量部を添加しエポキシ樹脂組成物を調製した。
得られたエポキシ樹脂組成物を厚さ３８μｍのＰＥＴフィルム上に乾燥後の厚さが５０μｍとなるようにロールコーターを用いて塗布した後、８０〜１２０℃で１０分間乾燥させることにより、層間樹脂絶縁層用樹脂フィルムを作製した。
【０２５４】
Ｂ．樹脂充填材の調製
実施例１と同様にして、樹脂充填材を調製した。
【０２５５】
Ｃ．多層プリント配線板の製造
（１）厚さ０．８ｍｍのガラスエポキシ樹脂またはＢＴ（ビスマレイミドトリアジン）樹脂からなる絶縁性基板３０の両面に１８μｍの銅箔３２がラミネートされている銅張積層板３０Ａを出発材料とした（図１１（ａ）参照）。まず、この銅張積層板３０Ａをドリル削孔し、無電解めっき処理を施し、パターン状にエッチングすることにより、基板の両面に下層導体回路３４とスルーホール３６を形成した（図１１（ｂ）参照）。
【０２５６】
（２）下層導体回路３４およびスルーホール３６を形成した基板を水洗いし、乾燥した後、ＮａＯＨ（１０ｇ／ｌ）、ＮａＣｌＯ₂ （４０ｇ／ｌ）、Ｎａ₃ ＰＯ₄ （６ｇ／ｌ）を含む水溶液を黒化浴（酸化浴）とする黒化処理、および、ＮａＯＨ（１０ｇ／ｌ）、ＮａＢＨ₄ （６ｇ／ｌ）を含む水溶液を還元浴とする還元処理を行い、そのスルーホール３６を含む下層導体回路３４の全表面に粗化面３８を形成した（図１１（ｃ）参照）。
【０２５７】
（３）上記Ｂに記載した樹脂充填材を調製した後、下記の方法により調製後２４時間以内に、スルーホール３６内、および、基板１の片面の下層導体回路非形成部と下層導体回路３４の外縁部とに樹脂充填材４０の層を形成した。
すなわち、まず、スキージを用いてスルーホール内に樹脂充填材を押し込んだ後、１００℃、２０分の条件で乾燥させた。次に、下層導体回路非形成部に相当する部分が開口したマスクを基板上に載置し、スキージを用いて凹部となっている下層導体回路非形成部に樹脂充填材４０の層を形成し、１００℃、２０分の条件で乾燥させた（図１１（ｄ）参照）。
【０２５８】
（４）上記（３）の処理を終えた基板の片面を、＃６００のベルト研磨紙（三共理化学製）を用いたベルトサンダー研磨により、内層銅パターン３４の表面やスルーホール３６のランド表面に樹脂充填材４０が残らないように研磨し、次いで、上記ベルトサンダー研磨による傷を取り除くためのバフ研磨を行った。このような一連の研磨を基板の他方の面についても同様に行った。
次いで、１００℃で１時間、１５０℃で１時間の加熱処理を行って樹脂充填材４０を硬化した。
【０２５９】
このようにして、スルーホール３６や下層導体回路非形成部に形成された樹脂充填材４０の表層部および下層導体回路３４の表面を平坦化し、樹脂充填材４０と下層導体回路３４の側面とが粗化面３８を介して強固に密着し、またスルーホール３６の内壁面と樹脂充填材４０とが粗化面３８を介して強固に密着した基板を得た（図１２（ａ）参照）。即ち、この工程により、樹脂充填材４０の表面と下層導体回路３４の表面とが同一平面となる。
【０２６０】
（５）上記基板を水洗、酸性脱脂した後、ソフトエッチングし、次いで、エッチング液を基板の両面にスプレイで吹きつけて、下層導体回路３４の表面とスルーホール３６のランド表面３６ａと内壁とをエッチングすることにより、下層導体回路３４の全表面に粗化面４２を形成した（図１２（ｂ）参照）。
エッチング液としては、イミダゾール銅（ＩＩ）錯体１０重量部、グリコール酸７重量部、塩化カリウム５重量部からなるエッチング液（メック社製、メックエッチボンド）を使用した。
【０２６１】
（６）次に、基板の両面に、Ａで作製した基板より少し大きめの層間樹脂絶縁層用樹脂フィルムを基板上に載置し、圧力４ｋｇｆ／ｃｍ² 、温度８０℃、圧着時間１０秒の条件で仮圧着して裁断した後、さらに、以下の方法により真空ラミネーター装置を用いて貼り付けることにより層間樹脂絶縁層２０を形成した（図１２（ｃ）参照）。すなわち、層間樹脂絶縁層用樹脂フィルムを基板上に、真空度０．５Ｔｏｒｒ、圧力４ｋｇｆ／ｃｍ² 、温度８０℃、圧着時間６０秒の条件で本圧着し、その後、１７０℃で３０分間熱硬化させた。
【０２６２】
（７）次に、層間樹脂絶縁層２０を形成した基板を、６０ｇ／ｌの過マンガン酸を含む８０℃の溶液に１０分間浸漬し、層間樹脂絶縁層２０の表面に存在するエポキシ樹脂粒子を溶解除去することにより、層間樹脂絶縁層２０の表面を粗面とした。なお、形成した粗面については、図示していない。
【０２６３】
（８）次に、日本真空技術社製のＳＶ−４５４０を用い、Ｃｕをターゲットにしたスパッタリングを、ガス圧０．５Ｐａ、温度１２０℃、電力６００Ｗ、時間３０分間の条件で行い、Ｃｕ金属層１２を層間樹脂絶縁層２０の表面に形成した（図１２（ｄ）参照）。なお、形成したＣｕ金属層の厚さは、０．５μｍである。
【０２６４】
（９）次に、Ｃｕ金属層上に、ドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５）を張り付け、マスクを載置して、１００ｍＪ／ｃｍ² で露光、０．８％炭酸ナトリウムで現像処理し、バイアホール用開口形成部に開口４３ａを有するエッチングレジスト４３を形成した（図１３（ａ）参照）。
【０２６５】
（１０）次に、開口４３ａ下のＣｕ金属層を塩化第二銅溶液からなるエッチング液にて除去し（図１３（ｂ）参照）、その後、エッチンレジスト４３を水酸化ナトリウム水溶液で剥離し、開口１２ａを有し、コンフォーマルマスクとなるＣｕ金属層１２を形成した（図１３（ｃ）参照）。
【０２６６】
（１１）次に、炭酸ガスレーザ照射装置（三菱電気社製 ６０５ＧＴＸ）を用いて、Ｃｕ金属層の開口１２ａ毎に５ショットの短パルスのレーザを照射し、層間樹脂絶縁層に直径６０μｍの開口を形成した（図１３（ｄ）参照）。この後、酸素プラズマを用いてデスミア処理を行った。
【０２６７】
（１２）次に、バイアホール用開口を形成した基板の表面に、パラジウム触媒を付与することにより、Ｃｕ金属層１２の表面およびバイアホール用開口２０ａの内壁面に触媒核を付着させた（図示せず）。すなわち、上記基板を塩化パラジウム（ＰｂＣｌ₂ ）と塩化第一スズ（ＳｎＣｌ₂ ）とを含む触媒液中に浸漬し、パラジウム金属を析出させることにより触媒を付与した。
【０２６８】
（１３）次に、以下の組成の無電解めっき用前処理液中に基板を浸漬することにより前処理を施した。
〔無電解めっき用前処理液〕
ＮａＯＨ ０．１０ ｍｏｌ／ｌ
ＨＣＨＯ ０．１０ ｍｏｌ／ｌ
〔前処理条件〕
３０℃液温度で３分
【０２６９】
（１４）次に、以下の組成の無電解銅めっき水溶液中に、前処理を施した基板を浸漬して、バイアホール用開口の内壁面を含む基板表面全体に厚さ０．６〜３．０μｍの無電解銅めっき膜５２を形成した（図１４（ａ）参照）。
〔無電解めっき水溶液〕
ＮｉＳＯ₄ ０．００３ ｍｏｌ／ｌ
酒石酸 ０．２００ ｍｏｌ／ｌ
硫酸銅 ０．０３０ ｍｏｌ／ｌ
ＨＣＨＯ ０．０５０ ｍｏｌ／ｌ
ＮａＯＨ ０．１００ ｍｏｌ／ｌ
α、α′−ビピリジル １００ ｍｇ／ｌ
ポリエチレングリコール（ＰＥＧ） ０．１０ ｇ／ｌ
〔無電解めっき条件〕
３４℃の液温度で４０分
【０２７０】
（１５）無電解銅めっき膜５２が形成された基板にドライフィルムレジスト（日合モートン社製 ＮＩＴ−２１５）を張り付け、所定位置にパターンの形成されたマスク（図示せず）を載置して、１００ｍＪ／ｃｍ² で露光した。その後、０．８％炭酸ナトリウムで現像処理し、バイアホール形成部および導体回路形成部に開口５４ａを有するめっきレジスト５４を設けた（図１４（ｂ）参照）。
【０２７１】
（１６）ついで、基板を５０℃の水で洗浄して脱脂し、２５℃の水で水洗後、さらに硫酸で洗浄してから、以下の条件で電解めっきを施し、めっきレジスト非形成部５４ａに、厚さ２０μｍの電解銅めっき膜５６を形成した（図１４（ｃ）参照）。
〔電解めっき液〕
硫酸 ２．２４ ｍｏｌ／ｌ
硫酸銅 ０．２６ ｍｏｌ／ｌ
添加剤 １９．５ ｍｌ／ｌ
（アトテックジャパン社製、カパラシドＧＬ）
〔電解めっき条件〕
電流密度 １ Ａ／ｄｍ²
時間 ６５ 分
温度 ２２±２ ℃
【０２７２】
（１７）さらに、めっきレジスト５４を５％ＫＯＨで剥離除去した後、そのめっきレジスト５４下の無電解めっき膜５２およびＣｕ金属層１２を硫酸と過酸化水素との混合液でエッチング処理して溶解除去し、独立の上層導体回路５８（バイアホール６０を含む）とした（図１４（ｄ）参照）。
【０２７３】
（１８）ついで、上記（５）と同様の処理を行い、上層導体回路５８（バイアホール６０を含む）表面に粗化面６２を形成した（図１５（ａ）参照）。
（１９）上記（６）〜（１８）の工程を繰り返すことにより、さらに上層導体回路８８（バイアホール９０を含む）と層間樹脂絶縁層１２０を形成し、多層配線板を得た（図１５（ｂ）参照）。
【０２７４】
（２０）さらに、実施例１の（１７）〜（２０）の工程と同様にして、ソルダーレジスト層および半田バンプを形成し、多層プリント配線板とした（図１６参照）。
【０２７５】
（比較例１）
無電解めっき用前処理液として、以下の組成の無電解めっき用前処理液を用いた以外は、実施例１と同様にして多層プリント配線板を製造した。
〔無電解めっき用前処理液〕
ＮａＯＨ ０．００５ｍｏｌ／ｌ
ＨＣＨＯ ０．１０ｍｏｌ／ｌ
【０２７６】
（比較例２）
無電解めっき用前処理液として、以下の組成の無電解めっき用前処理液を用いた以外は、実施例１と同様にして多層プリント配線板を製造した。
〔無電解めっき用前処理液〕
ＮａＯＨ ０．３０ｍｏｌ／ｌ
ＨＣＨＯ ０．１０ｍｏｌ／ｌ
【０２７７】
（比較例３）
無電解めっき用前処理液として、以下の組成の無電解めっき用前処理液を用いた以外は、実施例１と同様にして多層プリント配線板を製造した。
〔無電解めっき用前処理液〕
ＮａＯＨ ０．１０ｍｏｌ／ｌ
ＨＣＨＯ ０．０５ｍｏｌ／ｌ
【０２７８】
実施例１〜８および比較例１〜３で得られた多層プリント配線板において、無電解めっき膜の形状、および、無電解めっき膜のピール強度について評価を行った。結果を表１に示した。なお、無電解めっき膜の形状は、下記の評価方法により評価した。
また、上記多層プリント配線板について、導通試験を行い、断線の有無を評価した。結果を表１に示した。
【０２７９】
（１）無電解めっき膜の形状
多層プリント配線板をバイアホールを含むように縦に切断し、無電解めっき膜の形状を顕微鏡により観察し、以下の評価基準で評価した。
評価基準
○．無電解めっき膜の未析出部分がなく、厚さが均一である。
×．無電解めっき膜の未析出部分が存在したり、厚さにバラツキが生じたりしている。
【０２８０】
【表１】

【０２８１】
表１に示したように、本発明の多層プリント配線板の製造方法を用いて得られた多層プリント配線板（実施例１〜８）では、層間樹脂絶縁層や基板の表面全体に、厚さの均一な無電解めっき膜が形成されており、この無電解めっき膜のピール強度は０．９０ｋｇ／ｃｍ以上と充分に高く、また、得られた多層プリント配線板は、接続性も良好であった。
一方、比較例１〜３の多層プリント配線板は、層間樹脂絶縁層の表面全体に、厚さの均一な無電解めっき膜が形成されておらず、めっき膜の未析出部分や、厚さの不均一な部分が見られた。また、この無電解めっき膜のピール強度は０．７０ｋｇ／ｃｍ以下と無電解めっき膜の密着性は充分でなく、また、得られた多層プリント配線板は一部に接続不良がみられ、その接続性は、実施例と比べて低かった。
【０２８２】
【発明の効果】
以上説明してきたように、第一〜第四の本発明の多層プリント配線板の製造方法は、上述の構成からなるため、基板や層間樹脂絶縁層と導体回路との密着性が優れ、信頼性、電気特性に優れた多層プリント配線板を製造することができる。
【図面の簡単な説明】
【図１】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図２】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図３】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図４】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図５】（ａ）、（ｂ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図６】本発明の多層プリント配線板の製造方法により得られる多層プリント配線板を示す断面図である。
【図７】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図８】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図９】（ａ）〜（ｃ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図１０】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図１１】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図１２】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図１３】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図１４】（ａ）〜（ｄ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図１５】（ａ）、（ｂ）は、本発明の多層プリント配線板の製造方法の工程の一部を示す断面図である。
【図１６】本発明の多層プリント配線板の製造方法により得られる多層プリント配線板を示す断面図である。
【図１７】（ａ）〜（ｇ）は、従来のコンフォーマルマスクを用いた多層プリント配線板の製造工程の一部を示す断面図である。
【符号の説明】
２０、１２０ 層間樹脂絶縁層
３０、１３０ 絶縁性基板
３２ 銅箔
３４、１３４ 下層導体回路
３６ スルーホール
３８ 粗化面
４０ 樹脂充填材
４３ エッチングレジスト
５２ 無電解銅めっき膜
５４ めっきレジスト
５６ 電解銅めっき膜
５８、８８ 上層導体回路
６０、９０ バイアホール
９３ ソルダーレジスト層
９５ ニッケルめっき膜
９６ 金めっき膜
９７ はんだバンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a multilayer printed wiring board.
[0002]
[Prior art]
The multilayer printed wiring board can be manufactured by a method using a conformal mask as disclosed in, for example, Japanese Patent Publication No. 4-3676.
A manufacturing method using this conformal mask will be described below with reference to FIG.
[0003]
17 (a) to 17 (g) are cross-sectional views showing a part of a manufacturing process of a multilayer printed wiring board using a conventional conformal mask.
In this manufacturing method, first, a one-side copper-clad laminate in which a copper foil 104 is laminated on one side of a base material 101 is used as a starting material, and two of the one-side copper-clad laminates are laminated so that the copper foil 104 is on the upper side. And sticking together (see FIG. 17A).
Next, a photosensitive resin is uniformly applied on the copper foil 104, and an exposure development process is performed to form an etching resist 103 having an opening 103a in an opening forming portion for a via hole (FIG. 17B). )reference). Thereafter, the copper foil under the opening 103a is removed by etching to form an opening 104a, and the etching resist 103 is peeled off (see FIG. 17C).
[0004]
Further, the opening 104a formed in the copper foil is irradiated with laser light, and the via hole opening 106 is formed in the base material 101 using the copper foil 104 as a conformal mask (see FIG. 17D). Then, after imparting catalyst nuclei to the substrate surface, electroless copper plating is performed to deposit an electroless copper plating film 112 on the substrate surface including the wall surface of the via hole opening 106 (see FIG. 17E).
Next, the plating resist 113 is formed on the conductor circuit non-forming portion, and electrolytic plating is performed, thereby forming the electrolytic plating film 116 on the plating resist 113 non-forming portion (see FIG. 17F). Furthermore, after the plating resist 113 is peeled off, the electroless plating film 112 and the copper foil 104 under the plating resist 113 are removed by etching to form the via hole 107 and the conductor circuit 105 (see FIG. 17G). A multilayer printed wiring board can be manufactured by repeating such a process a plurality of times.
[0005]
Also, in the production of multilayer printed wiring boards, it is the mainstream to use EDTA as a complexing agent as an electroless plating solution for forming a conductor circuit. For example, JP-A-63-158156 and An example of forming a conductor circuit using such an electroless plating solution is described in the examples of JP-A-2-1888992 (US Pat. No. 5,055,321 and US Pat. No. 5,519,177). ing.
[0006]
[Problems to be solved by the invention]
However, in such an electroless plating solution using EDTA as a complexing agent, a compressive stress (force to spread) is generated in the deposited plating film, and the plating film peels off from the wall surface of the via hole opening or the metal foil. There was a problem of doing so.
This is because when forming a plating film, hydrogen is taken into the plating film, and this hydrogen serves as a stress generation source to generate compressive stress.
In addition, there was a problem that plating did not deposit in a fine via hole opening having a diameter of 80 μm or less.
[0007]
Therefore, the present inventors have found that when tartaric acid is used as a complexing agent, the incorporation of hydrogen into the plating film is suppressed, and a plating film that is less likely to generate compressive stress can be formed. And an electroless plating solution comprising an aqueous solution containing an alkaline compound, a reducing agent, copper ions, and tartaric acid or a salt thereof.
[0008]
However, when an electroless plating film is formed on the substrate surface or the via hole opening using this electroless plating solution, a portion where the plating film is insufficiently deposited or an undeposited portion may be generated. Such a phenomenon was often observed in the vicinity of the through hole for the through hole or the opening for the via hole.
This is because the activation of the catalyst applied when forming the electroless plating film is insufficient, or the catalyst is inactivated before the electroless plating treatment is performed after the application of the catalyst. It is thought that there is not.
[0009]
In addition, in order to form an electroless plating film that is uniform and excellent in adhesiveness, a pretreatment is usually performed on an object to be plated before the electroless plating treatment.
Techniques for performing such pretreatment are disclosed in, for example, WO96 / 20294, JP-A-7-278823, JP-A-6-299360, and the like.
[0010]
WO96 / 20294 discloses a pretreatment solution for electroless plating comprising a pH adjuster, a reducing agent and a complexing agent. This pretreatment liquid for electroless plating stabilizes the deposition property of the plating film by adjusting the surface potential of the metal film.
Therefore, when an electroless plating film is formed on a metal film, an electroless plating film that is uniform and excellent in adhesion can be formed. However, it can be used as a through hole for a through hole or a wall surface of a via hole. However, when an electroless plating film is formed on the surface of an object to be plated whose material is a resin, a uniform electroless plating film is not formed, and the above problem cannot be solved.
[0011]
Japanese Patent Application Laid-Open No. 7-278823 discloses a method of treating the surface of a metal object with an alkaline aqueous solution. According to the said method, the thin film of hydroxide is formed in the to-be-plated object surface, and the effect that the adhesiveness of a plating film improves by this is described.
However, after treating the inside of the opening for via holes using the pretreatment liquid disclosed here, an electroless solution comprising an aqueous solution containing the above-described alkaline compound, reducing agent, copper ion, and tartaric acid or a salt thereof. An electroless plating film was formed in the via hole opening using a plating solution, but a uniform plating film was not formed, and the above problem could not be solved.
[0012]
The present invention has been made in order to solve the above-described problems, and its purpose is to provide an electroless film that is uniform and excellent in adhesion to the wall surface of the through hole for the through hole, the wall surface of the opening for the via hole, and the like. It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board that can form a plating film and, as a result, can manufacture a multilayer printed wiring board having excellent connection reliability and electrical characteristics.
[0013]
[Means for Solving the Problems]
As a result of intensive studies aimed at realizing the above object, the present inventors have found that 0.01 to 0.25 mol / l of an alkaline compound and 0% before electroless plating treatment in the production of a multilayer printed wiring board. Through hole for through-hole when performing electroless plating treatment by performing pretreatment using a pretreatment liquid for electroless plating comprising an aqueous solution containing 0.1 to 0.3 mol / l reducing agent. It is found that the plating film is uniformly deposited on the surface of the object to be plated, such as openings for via holes and metal layers, and the formed plating film has excellent adhesion to the object to be plated. The invention of the gist configuration has been reached.
[0020]
That is,FirstoneIn the method for producing a multilayer printed wiring board according to the present invention, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated on a substrate on which a lower layer conductor circuit is formed, and these conductor circuits are connected via via holes. A multilayer printed wiring board manufacturing method comprising:
The step of forming the upper layer conductor circuit includes at least
(A) forming a resin / metal layer composed of a resin layer and a metal layer on the lower conductor circuit or the upper conductor circuit;
(B) The resin layer and the metal layer constituting the resin / metal layer are sequentially subjected to an opening forming process, and an opening for a via hole is formed by the opening forming process.Furthermore, a Pd catalyst is added.The process of
(C) In the resin / metal layer,0.025 to 0.1 mol / lA step of performing a pretreatment using a pretreatment solution for electroless plating, which comprises an aqueous solution containing an alkaline compound of 0.1 and 0.3 to 0.3 mol / l of a reducing agent,
(D) Pretreatment described aboveofForming an electroless plating film on the surface of the applied resin / metal layer;
(E) forming a plating resist on a part of the electroless plating film;
(F) forming an electrolytic plating film on the plating resist non-forming portion; and
(G) After removing the plating resist, a process for removing the electroless plating film and the metal layer under the plating resistIncluding,
In the step (B), the diameter of the opening for the via hole is 80 μm or less,
In the step (C), the pretreatment temperature is 20 to 50 ° C., the pretreatment time is 0.5 to 5 minutes,
The electroless plating solution used in the step (D) is composed of an aqueous solution containing an alkaline compound, a reducing agent, copper ions, and tartaric acid or a salt thereof, and further selected from the group consisting of nickel ions, cobalt ions, and iron ions. At least one metal ion
The concentration of the alkaline compound is 0.025 to 0.25 mol / l,
The concentration of the reducing agent is 0.03 to 0.15 mol / l,
The concentration of the copper ion is 0.02 to 0.06 mol / l,
The density | concentration of the said tartaric acid or its salt is 0.05-0.3 mol / l.
[0021]
The secondtwoIn the method for producing a multilayer printed wiring board according to the present invention, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated on a substrate on which a lower layer conductor circuit is formed, and these conductor circuits are connected via via holes. A multilayer printed wiring board manufacturing method comprising:
The step of forming the upper layer conductor circuit includes at least
(A) forming a resin / metal layer composed of a resin layer and a metal layer on the lower conductor circuit or the upper conductor circuit;
(B) The resin layer and the metal layer constituting the resin / metal layer are sequentially subjected to an opening forming process, and an opening for a via hole is formed by the opening forming process.Furthermore, a Pd catalyst is added.The process of
(C) In the resin / metal layer,0.025 to 0.1 mol / lA step of performing a pretreatment using a pretreatment solution for electroless plating, which comprises an aqueous solution containing an alkaline compound of 0.1 and 0.3 to 0.3 mol / l of a reducing agent,
(D) Pretreatment described aboveofForming an electroless plating film on the surface of the applied resin / metal layer;
(E) forming an electrolytic plating film on the electroless plating film;
(F) forming an etching resist on a part of the electrolytic plating film; and
(G) A process for removing the electrolytic plating film, electroless plating film and metal layer under the etching resist non-forming portion by etching treatment.Including,
In the step (B), the diameter of the opening for the via hole is 80 μm or less,
In the step (C), the pretreatment temperature is 20 to 50 ° C., the pretreatment time is 0.5 to 5 minutes,
The electroless plating solution used in the step (D) is composed of an aqueous solution containing an alkaline compound, a reducing agent, copper ions, and tartaric acid or a salt thereof, and further selected from the group consisting of nickel ions, cobalt ions, and iron ions. At least one metal ion
The concentration of the alkaline compound is 0.025 to 0.25 mol / l,
The concentration of the reducing agent is 0.03 to 0.15 mol / l,
The concentration of the copper ion is 0.02 to 0.06 mol / l,
The density | concentration of the said tartaric acid or its salt is 0.05-0.3 mol / l.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing a multilayer printed wiring board according to the first aspect of the present invention, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated on a substrate on which a lower layer conductor circuit is formed, and these conductor circuits are connected via via holes. It is a manufacturing method of the multilayer printed wiring board connected, Comprising: The process of forming the lower layer conductor circuit of the following (a)-(g) is included at least.
(A) forming a metal layer on the substrate;
(B) A step of sequentially performing an opening formation process on the metal layer and the substrate, and forming a through hole in the substrate on which the metal layer is formed by the opening formation process;
(C) Before electroless plating comprising an aqueous solution containing 0.01 to 0.25 mol / l of an alkaline compound and 0.1 to 0.3 mol / l of a reducing agent on the substrate on which the through hole is formed. A step of performing a pretreatment using a treatment liquid;
(D) a step of forming an electroless plating film on the surface of the substrate that has been subjected to the pretreatment;
(E) a step of forming a plating resist on a part of the electroless plating film;
(F) forming an electrolytic plating film on the plating resist non-forming portion; and
(G) A step of removing the electroless plating film and the metal layer under the plating resist after removing the plating resist.
[0027]
According to the method for producing a multilayer printed wiring board of the first aspect of the present invention, before performing an electroless plating process for forming a lower layer conductor circuit (including a through hole) on a substrate, 0.01 to 0.25 mol. In order to pre-treat the substrate on which the through-holes are formed using a pre-treatment solution for electroless plating comprising an aqueous solution containing a / l alkaline compound and 0.1 to 0.3 mol / l reducing agent, A uniform electroless plating film having excellent adhesion to the substrate can be formed by electrolytic plating, and as a result, a multilayer printed wiring board having excellent connection reliability and electrical characteristics can be produced.
[0028]
Usually, when performing an electroless plating treatment, it is necessary to previously apply a catalyst to the surface of the object to be plated. For example, after depositing palladium metal or the like as a catalyst on the surface of the object to be plated, Although the treatment is performed, the palladium deposited on the surface of the object to be plated in this way is oxidized when left in the air or in water and loses its activity as a catalyst.
However, in the method for producing a multilayer printed wiring board according to the first aspect of the present invention, the catalyst is applied to the surface of the substrate including the wall surface of the through hole, and then pretreatment is performed using the pretreatment liquid for electroless plating. The catalyst that has been oxidized and has lost its activity can be reduced again to regain its activity as a catalyst.
[0029]
Below, the manufacturing method of the multilayer printed wiring board of 1st this invention is demonstrated in detail.
In addition, the manufacturing method of the multilayer printed wiring board of the first aspect of the present invention (hereinafter also simply referred to as the first manufacturing method) is a step of forming a lower layer conductor circuit (including through holes) on a substrate, that is, the above ( Since it has characteristics in the steps a) to (g), the steps (a) to (g) will be described first, and all the manufacturing steps for manufacturing the multilayer printed wiring board will be described in detail later. I will do it.
[0030]
In the first manufacturing method, the lower conductor circuit including the through hole is formed on the substrate by performing the steps (a) to (g).
First, a metal layer is formed on a substrate (step (a)).
Specifically, for example, it is formed by attaching a metal foil on a substrate or performing physical vapor deposition or chemical vapor deposition such as sputtering or vacuum vapor deposition.
Further, the metal layer may be formed by electroless plating. In this case, it is desirable to perform the electroless plating after the substrate is pretreated using a pretreatment liquid for electroless plating, which will be described in detail later.
The substrate is preferably a resin substrate, and specific examples include, for example, a glass epoxy substrate, a polyester substrate, a polyimide substrate, a bismaleimide-triazine resin substrate, a thermosetting polyphenylene ether substrate, an FR-4 substrate, and an FR-5 substrate. And a fluororesin substrate.
[0031]
Moreover, as a material of the said metal layer, copper, nickel, aluminum, chromium, iron, a noble metal (gold, silver, palladium, platinum) etc. are mentioned, for example.
Moreover, you may use a commercially available copper clad laminated board, a RCC board | substrate, etc. as a board | substrate with which the metal layer was formed.
[0032]
Next, an opening forming process is sequentially performed on the metal layer and the substrate, and through holes are formed on the substrate on which the metal layer is formed by the opening forming process (step (b)). In the present specification, the process for forming a through hole and the process for forming a non-through hole are both referred to as an opening forming process.
In this step, first, an opening is formed in the metal layer formed on the substrate, and then a through hole is formed in the substrate below the opening formed in the metal layer.
[0033]
As a method for forming the opening in the metal layer, for example, the following method can be used.
That is, an opening can be formed by forming an etching resist on a part of the metal layer (a part corresponding to a part where no opening is formed) and then performing etching.
The etching resist can be formed, for example, by applying a photosensitive dry film or applying a liquid resist and then performing an exposure development process.
Examples of the etching solution used in the etching include sulfuric acid-hydrogen peroxide aqueous solution, persulfate aqueous solution such as ammonium persulfate and potassium persulfate, aqueous solution such as ferric chloride and cupric chloride, hydrochloric acid, nitric acid, Examples include hot dilute sulfuric acid.
Moreover, the etching liquid containing a cupric complex and an organic acid can also be used.
[0034]
In this step, it is desirable to set the thickness of the metal layer to about 0.5 to 5 μm before forming the opening in the metal layer. If the thickness of the metal layer is less than 0.5 μm, the metal layer may not be able to serve as a conformal mask when a through hole is formed in the substrate in a later process. When the thickness exceeds 5 μm, the shape of the through hole may not be a desired shape when the through hole is formed by laser processing.
[0035]
Next, the etching resist is removed, and a through hole is formed in the substrate using the metal layer having the opening as a conformal mask.
The through hole can be formed by, for example, laser processing.
At this time, examples of the laser to be used include a carbon dioxide laser, an excimer laser, a UV laser, and a YAG laser.
These lasers may be used properly in consideration of the shape of the through hole to be formed.
Further, it is desirable that the beam diameter at the time of performing laser processing is 1.3 times or more the opening diameter of the through hole to be formed. This is because a through hole having a desired shape can be formed.
[0036]
It is desirable to perform desmear treatment after the through hole is formed by the laser treatment. This is because the connection reliability and electrical characteristics of the resulting multilayer printed wiring board can be further improved.
The desmear treatment can be performed using, for example, an oxidizing agent made of an aqueous solution of chromic acid or permanganate. Oxygen plasma, CF_Four And may be treated with a mixed plasma of oxygen and oxygen, corona discharge, or the like. Moreover, you may process by irradiating an ultraviolet-ray using a low pressure mercury lamp.
[0037]
Next, before the electroless plating, the substrate having the through holes formed thereon is formed of an aqueous solution containing 0.01 to 0.25 mol / l alkaline compound and 0.1 to 0.3 mol / l reducing agent. A pretreatment using a treatment solution is performed (step (c)).
In addition, it is desirable that a catalyst such as palladium metal is previously applied to the surface of the substrate on which the through hole is formed before the pretreatment.
[0038]
In the case of using palladium metal as the catalyst, the catalyst can be imparted by using, for example, the following method.
That is, the substrate on which the through hole is formed is made of palladium chloride (PbCl₂ ) And stannous chloride (SnCl)₂ ), And by depositing palladium ions as palladium metal on the wall surface of the through-hole or on the surface of the metal layer formed on the substrate by the reducing power of stannous ions. Can be granted.
[0039]
Examples of the alkaline compound in the electroless plating pretreatment liquid include potassium hydroxide, sodium hydroxide, lithium hydroxide, and calcium hydroxide.
In addition, when the concentration of these alkaline compounds is less than 0.01 mol / l, the pH of the pretreatment liquid for electroless plating may be low, and the reducing action by the reducing agent may be insufficient. If it exceeds 0.25 mol / l, the reducing agent may be decomposed, so the concentration of the alkaline compound is limited to the above range.
[0040]
Examples of the reducing agent include sodium hypophosphite, aldehyde, borohydride, hydrazine and the like.
In addition, when the concentration of these reducing agents is less than 0.1 mol / l, there is almost no reducing action. On the other hand, even when the concentration of the reducing agent exceeds 0.3 mol / l, the reducing action remains almost unchanged, Since it is only economically disadvantageous, the concentration of the reducing agent is limited to the above range.
[0041]
The pretreatment liquid for electroless plating desirably contains no metal ions or complexing agents in the aqueous solution.
When metal ions and complexing agents are included, when the substrate is pretreated with the electroless plating pretreatment solution, the activated ions existing on the wall surfaces of the through holes are activated. The catalyst reacts with metal ions or the like, and the number of catalysts that are insufficiently activated increases. In this case, the initial reactivity during the electroless plating process is suppressed, and the plating film is not uniformly deposited.
[0042]
The reason for this will be described taking the case of using palladium as a catalyst as an example.
That is, when the substrate having the through hole is immersed in a solution containing palladium chloride, for example, palladium ions are reduced by other metal ions, and deposited as palladium metal on the wall surface of the through hole, This palladium metal has activity as a catalyst.
Here, when palladium metal is oxidized, the activity as a catalyst is lost. As a result, the proportion of palladium metal having activity as a catalyst is reduced, which leads to a decrease in initial reactivity during plating. Therefore, a plating film is formed on the wall surface of the through hole or the surface of the metal layer formed on the substrate. Will not be deposited uniformly.
[0043]
In the first production method, after the catalyst is applied, the pretreatment is performed using the pretreatment liquid for electroless plating, so that the catalyst can be sufficiently activated by this pretreatment. By performing the plating treatment, an electroless plating film that is uniform and excellent in adhesion can be formed. Thus, when the pretreatment liquid for electroless plating is used, the object to be plated is made of a metal such as a metal layer, even if the object to be plated is made of a resin such as a substrate. Even so, a uniform electroless plating film can be formed on the surface of the object to be plated by the electroless plating treatment.
[0044]
The pretreatment is performed by immersing the substrate in which the through holes are formed in the pretreatment liquid for electroless plating.
At this time, the temperature of the pretreatment liquid for electroless plating is desirably 20 to 50 ° C.
[0045]
If the temperature of the pretreatment liquid for electroless plating is less than 20 ° C., the catalyst cannot be sufficiently reduced, and the proportion of unreduced catalyst increases, so that the reactivity, that is, the plating film deposition is insufficient. On the other hand, if the liquid temperature exceeds 50 ° C., the reducing agent is likely to be deteriorated, and the reactivity during plating is hardly improved, which is economically disadvantageous.
A more desirable liquid temperature is 25 to 40 ° C.
[0046]
The immersion time in the pretreatment liquid for electroless plating, that is, the pretreatment time is preferably 0.5 to 5 minutes.
When the pretreatment time is less than 0.5 minutes, the catalyst applied in the previous step may not be sufficiently reduced. On the other hand, even when the pretreatment time exceeds 5 minutes, the reactivity during plating is almost zero. It is because it does not improve.
[0047]
Next, an electroless plating film is formed on the surface of the substrate that has been subjected to the pretreatment, that is, the wall surface of the through hole and the surface of the metal layer on the substrate (step (d)).
The electroless plating film is formed by immersing the substrate in which the through holes are formed in an electroless plating solution.
[0048]
Although it does not specifically limit as said electroless-plating liquid, What consists of an aqueous solution containing an alkaline compound, a reducing agent, copper ion, and tartaric acid or its salt is preferable.
This is because the electroless plating solution is suitable as a treatment solution used when forming an electroless plating film having a uniform and excellent adhesion on the surface of an object to be plated made of resin or metal. The reason is that the plating film formed by the electroless plating solution has a small amount of hydrogen uptake and an appropriate tensile strength.
[0049]
In the electroless plating solution, examples of the alkaline compound include sodium hydroxide, potassium hydroxide, and ammonia.
The concentration is preferably 0.025 to 0.25 mol / l.
By adjusting the concentration of the alkaline compound to the above range, the plating deposition rate can be reduced to 1 to 2 μm / hour, so that a uniform electroless plating film can be formed on the wall surface of the through hole. In particular, even when the opening diameter of the through-hole is small, an electroless plating film that is uniform on the wall surface and excellent in adhesion can be formed.
[0050]
Examples of the reducing agent include formaldehyde, sodium hypophosphite, NaBH._Four , Hydrazine and the like.
The concentration is preferably 0.03 to 0.15 mol / l.
This is because the plating deposition rate can be reduced to 1 to 2 μm / hour by adjusting the concentration of the reducing agent within the above range.
[0051]
Examples of the compound for forming the copper ion include copper sulfate and copper chloride.
Moreover, as for the density | concentration, it is desirable that it is 0.02-0.06 mol / l in the density | concentration of a copper ion.
By adjusting the copper ion concentration to the above range, an electroless plating film that is uniform and has excellent adhesion on the wall surface of the through-hole is formed even when the opening diameter of the through-hole to be subjected to electroless plating is small can do.
[0052]
Examples of the salt of tartaric acid include sodium salt and potassium salt, and these salts may be salts in which only one of two carboxyl groups is substituted with the metal. Each of them may be a salt substituted with the above metal.
The concentration is preferably 0.05 to 0.3 mol / l.
By adjusting the concentration of tartaric acid or a salt thereof within the above range, an electroless plating film having better adhesion can be formed.
[0053]
Further, the electroless plating solution preferably further contains at least one metal ion selected from the group consisting of nickel ions, cobalt ions, and iron ions.
This is because the generation of hydrogen is suppressed, and as a result, an appropriate tensile stress is generated in the plating film and adheres to the substrate, so that the plating film hardly peels off.
[0054]
Examples of the compound for forming the nickel ion include nickel chloride and nickel sulfate. Examples of the compound for forming the cobalt ion include cobalt chloride and the like to form the iron ion. As a compound for doing, iron chloride etc. are mentioned, for example.
[0055]
In this step, the temperature of the electroless plating solution when performing electroless plating is preferably 25 to 35 ° C., and the immersion time in the electroless plating solution is preferably 10 to 20 minutes.
[0056]
Next, a plating resist is formed on a part of the electroless plating film formed in the step (d), that is, a portion corresponding to the lower conductor circuit non-forming portion (step (e)).
The plating resist can be formed, for example, by applying a photosensitive dry film or applying a liquid resist and then performing an exposure development process.
[0057]
Next, an electrolytic plating film is formed on the plating resist non-forming portion (step (f)). The electrolytic plating film can be formed by using the already formed electroless plating film as a plating lead.
Specifically, for example, an electrolytic copper plating film can be formed by using an electrolytic plating solution containing sulfuric acid, copper sulfate and an additive.
[0058]
Next, the plating resist is peeled off, and then the electroless plating film and the metal layer under the plating resist are removed by an etching process (step (g)).
Here, examples of the etching solution used for removing the electroless plating film and the metal layer include a sulfuric acid-hydrogen peroxide aqueous solution, a persulfate aqueous solution such as ammonium persulfate and potassium persulfate, ferric chloride, and cupric chloride. And an etching solution containing a cupric complex and an organic acid.
Further, physical etching such as ion beam etching may be used.
In consideration of the material of the electroless plating film and the metal layer, etc., the etching solution used for each removal may be properly used.
[0059]
Through the steps (a) to (g), a lower layer conductor circuit (including through holes) can be formed on the substrate.
Moreover, in the method for producing a multilayer printed wiring board according to the first aspect of the present invention, before forming the electroless plating film, the electroless plating pretreatment liquid having the above composition is used to form the through holes formed in the substrate. Since the wall surface and the like are pretreated, a multilayer printed wiring board having a lower layer conductor circuit having excellent adhesion to the substrate can be manufactured.
In this specification, the conductor circuit formed on the surface of the substrate is referred to as a lower layer conductor circuit, and the conductor circuit formed on the interlayer resin insulation layer is referred to as an upper layer conductor circuit to distinguish between them. . When both are included, it is simply referred to as a conductor circuit.
[0060]
Next, all manufacturing steps of the first manufacturing method will be described in the order of steps.
(1) In the method for producing a multilayer printed wiring board according to the first aspect of the present invention, first, a substrate on which a lower layer conductor circuit and a through hole are formed is produced by using the methods (a) to (g).
[0061]
(2) Next, if necessary, the inner wall of the through hole and the surface of the lower conductor circuit are roughened. Examples of the roughening treatment method include blackening (oxidation) -reduction treatment, etching treatment, treatment with Cu—Ni—P needle-shaped alloy plating, and the like.
[0062]
Specific examples of the blackening (oxidation) -reduction treatment include NaOH (10 to 20 g / l), NaClO.₂ (40-50 g / l), Na_Three PO_Four Blackening treatment using an aqueous solution containing (6-15 g / l) as a blackening bath (oxidation bath), and NaOH (2.7-10 g / l), NaBH_Four Examples include a method of performing a reduction treatment using an aqueous solution containing (1.0 to 6.0 g / l) as a reduction bath.
[0063]
As an etching solution used for the etching treatment, a mixed solution of an organic acid and a cupric complex is desirable. Examples of the organic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, acrylic acid, crotonic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, benzoic acid, glycolic acid, Examples include lactic acid, malic acid, sulfamic acid and the like. These may be used alone or in combination of two or more. In the etching solution, the organic acid content is preferably 0.1 to 30% by weight. This is because the solubility of oxidized copper can be maintained and catalyst stability can be ensured.
[0064]
The cupric complex is preferably an azole cupric complex. This cupric complex of azoles acts as an oxidizing agent that oxidizes metallic copper and the like. Examples of azoles include diazole, triazole, and tetrazole. Among these, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and 2-undecylimidazole are desirable. In the etching solution, the content of the cupric complex is preferably 1 to 15% by weight. It is because it is excellent in solubility and stability.
[0065]
Examples of the plating treatment include copper sulfate (1 to 40 g / l), nickel sulfate (0.1 to 6.0 g / l), citric acid (10 to 20 g / l), and sodium hypophosphite (10 to 10 g / l). 100 g / l), boric acid (10-40 g / l) and surfactant (manufactured by Nissin Chemical Industry Co., Surfinol 465) (0.01-10 g / l) in an electroless plating bath of pH = 9 And a method of forming a roughened layer made of a Cu-Ni-P alloy by electroless plating.
This is because the crystal structure of the plating film deposited in this range is a needle-like structure, which is excellent in anchor effect. In addition to the above compounds, complexing agents and additives may be added to the electroless plating bath.
[0066]
(3) Next, a resin filler is filled into the through hole. If necessary, the insulating substrate surface may be planarized by filling a resin filler in a recess where a lower conductor circuit is not formed on the substrate, and then performing polishing or the like.
Thereafter, the resin filler is dried under conditions of, for example, 100 ° C./20 minutes, and then cured.
[0067]
The resin filler is preferably cured at a temperature of 50 to 250 ° C. An example of the curing condition is a method of heating at 100 ° C. for 1 hour and then heating at 150 ° C. for 1 hour. As needed, you may perform step hardening which makes it harden | cure by changing high temperature and temperature from low temperature sequentially.
[0068]
Further, when the surface of the conductor layer is flattened by polishing, the lower-layer conductor circuit may be roughened once more as necessary. Examples of the roughening treatment method include blackening (oxidation) -reduction treatment, etching treatment, treatment with Cu—Ni—P alloy plating, and the like.
[0069]
(4) Next, an uncured resin insulating layer made of a thermosetting resin or a resin composite is formed on the lower conductor circuit, or a resin layer made of a thermoplastic resin is formed.
The uncured resin insulation layer may be formed by applying uncured resin with a roll coater, curtain coater, or the like, or by thermocompression bonding of an uncured (semi-cured) resin film. Good. Furthermore, you may affix the resin film in which metal layers, such as copper foil, were formed in the single side | surface of an uncured resin film.
The resin layer made of a thermoplastic resin is preferably formed by thermocompression bonding a resin molded body formed into a film shape.
[0070]
In the case of applying the uncured resin, the resin is applied and then heat treatment is performed.
By performing the heat treatment, the uncured resin can be thermoset.
In addition, you may perform the said thermosetting, after forming the opening for via holes and a through-hole which are mentioned later.
[0071]
Further, when an interlayer resin insulation layer is formed by pasting the resin film, the formation of the interlayer resin insulation layer is performed by pressing the resin film under reduced pressure or under vacuum using an apparatus such as a vacuum laminator, This is done by thermosetting the resin film.
In addition, you may perform the said thermosetting, after forming the opening for via holes and a through-hole which are mentioned later.
[0072]
In addition, when a thermoplastic resin molded into a film is thermocompression bonded to the lower conductor circuit, an apparatus such as a vacuum laminator is used to crimp the thermoplastic resin molded into a film under reduced pressure or under vacuum. It is desirable.
[0073]
Specific examples of the thermosetting resin include, for example, epoxy resins, phenol resins, polyimide resins, polyester resins, bismaleimide resins, polyolefin resins, polyphenylene ether resins, and the like.
[0074]
Examples of the epoxy resin include cresol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol F type epoxy resin, naphthalene type epoxy resin, Examples thereof include cyclopentadiene type epoxy resins, epoxidized products of condensates of phenols and aromatic aldehydes having a phenolic hydroxyl group, triglycidyl isocyanurate, and alicyclic epoxy resins. These may be used alone or in combination of two or more. Thereby, it will be excellent in heat resistance.
[0075]
Examples of the polyolefin resin include polyethylene, polypropylene, polyisobutylene, polybutadiene, polyisoprene, cycloolefin resin, and copolymers of these resins.
[0076]
Moreover, as a commercial item of the said polyolefin resin, Sumitomo 3M Co., Ltd. brand name: 1592 etc. are mentioned, for example. Moreover, as a commercial item of thermoplastic polyolefin-type resin whose melting | fusing point is 200 degreeC or more, the brand name: TPX (melting | fusing point 240 degreeC) made by Mitsui Petrochemical Industry Co., Ltd., the brand name made by Idemitsu Petrochemical Co., Ltd .: SPS ( Melting point of 270 ° C.).
Among these, the dielectric constant and dielectric loss tangent are low, and even when a high frequency signal in the GHz band is used, signal delay and signal error are not easily generated. Olefin resins are desirable.
[0077]
As the cycloolefin-based resin, a homopolymer or copolymer of a monomer composed of 2-norbornene, 5-ethylidene-2-norbornene, or a derivative thereof is desirable. Examples of the derivative include those in which an amino group for forming a bridge, a maleic anhydride residue, or a maleic acid-modified one is bonded to the cycloolefin such as 2-norbornene.
Examples of the monomer for synthesizing the copolymer include ethylene and propylene.
[0078]
The cycloolefin-based resin may be a mixture of two or more of the above-described resins, or may include a resin other than the cycloolefin-based resin.
Moreover, when the said cycloolefin resin is a copolymer, a block copolymer may be sufficient and a random copolymer may be sufficient.
[0079]
The cycloolefin resin is preferably a thermosetting cycloolefin resin. This is because by heating to form a crosslink, the rigidity becomes higher and the mechanical properties are improved.
The glass transition temperature (Tg) of the cycloolefin resin is preferably 130 to 200 ° C.
[0080]
The cycloolefin resin may be a resin sheet (film) that has already been molded, and a monomer or a low molecular weight polymer having a certain molecular weight is dispersed in a solvent such as xylene or cyclohexane. It may be in an uncured solution state.
In the case of a resin sheet, so-called RCC (RESIN COATED copper) may be used.
The cycloolefin-based resin may contain a flame retardant such as aluminum hydroxide, magnesium hydroxide, or phosphate ester.
[0081]
The polyolefin resin may contain an organic filler.
By including the organic filler, for example, when the via hole opening is formed by irradiating the interlayer resin insulating layer with laser light, the via hole opening having a desired shape can be satisfactorily formed.
[0082]
In other words, when an infrared laser such as a carbon dioxide laser is irradiated to form an opening for a via hole, the organic filler serves as a buffer against heat, and the generated heat and heat reflected from the conductor circuit are reduced. Absorb part. The organic filler serves as a mechanical reinforcing agent for maintaining the predetermined shape of the resin composition, and as a result, the shape of the surrounding resin can be maintained. For example, an opening can be formed.
[0083]
In addition, when forming an opening for a via hole or the like by irradiating with an ultraviolet laser, the organic filler absorbs the ultraviolet ray, and therefore, the interlayer resin insulating layer in the portion irradiated with the ultraviolet laser is decomposed and disappeared, which is the target. Shaped openings for via holes and the like can be formed.
[0084]
Accordingly, when a via hole is formed by forming a via hole opening by irradiation with the laser and forming a metal layer in the opening, the metal layer is in close contact with the lower conductor circuit and is not easily peeled off. Wiring board connectivity and reliability are improved.
[0085]
Although it does not specifically limit as said organic filler, For example, a melamine, a phenol resin, an epoxy resin, a polyimide resin, a fluororesin, PPO, PPE etc. are mentioned. These compounds may be used alone or in combination of two or more.
[0086]
The content of the organic filler is preferably 5 to 60% by weight. When the content of the organic filler is less than 5% by weight, the content of the organic filler is too small, so that the above-mentioned role cannot be performed when the laser beam is irradiated, and the intended shape for the via hole is used. In some cases, an opening or the like cannot be formed. On the other hand, when the content of the organic filler exceeds 60% by weight, the characteristics of the polyolefin resin are lost, and for example, the dielectric constant becomes too high. A more preferable content of the organic filler is 14 to 60% by weight.
[0087]
The shape of the organic filler is not particularly limited, and examples thereof include a spherical shape and a polyhedral shape. Among these, cracks are unlikely to occur, and even if stress is generated in the interlayer resin insulation layer due to heat or thermal shock. From the viewpoint that the stress is easily relieved, a spherical shape is preferable.
[0088]
The particle size of the organic filler is preferably 0.05 to 0.2 μm. If the particle size of the organic filler is less than 0.05 μm, the particle size is too small, so it may be difficult to uniformly mix the organic filler, while the particle size of the organic filler is 0.2 μm. If it exceeds 1, the particle size of the organic filler is too large, so that it may not be completely decomposed and removed when irradiated with laser light.
[0089]
When blending the organic filler, two or more kinds of organic fillers having different particle sizes may be blended. However, when too many organic fillers having different particle sizes are blended, the organic filler is likely to aggregate and agglomerate. Since the diameter of the product exceeds 0.2 μm and the same inconvenience as when using a material exceeding 0.2 μm may occur, when blending organic fillers having different diameters, only two types of blending are used. It is desirable.
[0090]
Examples of the polyphenylene ether resin include a thermoplastic polyphenylene ether resin having a repeating unit represented by the following chemical formula (1) and a thermosetting polyphenylene ether resin having a repeating unit represented by the following chemical formula (2). It is done.
[0091]
[Chemical 1]

[0092]
(In the formula, n represents an integer of 2 or more.)
[0093]
[Chemical 2]

[0094]
(In the formula, m represents an integer of 2 or more. Also, R¹ , R² Is a methylene group, ethylene group or -CH₂ -O-CH₂ -Represents that both may be the same or different. )
[0095]
Further, the thermoplastic polyphenylene ether resin having a repeating unit represented by the chemical formula (2) has a structure in which a methyl group is bonded to a benzene ring, but as a polyphenylene ether resin that can be used in the present invention, Further, a derivative in which the methyl group is substituted with another alkyl group such as an ethyl group, a derivative in which hydrogen of the methyl group is substituted with fluorine, or the like may be used.
[0096]
Examples of the thermoplastic resin include phenoxy resin, polyether sulfone, and polysulfone.
Further, these composites (resin composites) are not particularly limited as long as they contain a thermosetting resin and a thermoplastic resin, and specific examples thereof include, for example, a roughened surface-forming resin composition. Etc.
[0097]
Examples of the roughened surface-forming resin composition include, in an uncured heat-resistant resin matrix that is hardly soluble in a roughened liquid consisting of at least one selected from an acid, an alkali, and an oxidizing agent. And a material in which a substance soluble in a roughening liquid comprising at least one selected from oxidizing agents is dispersed.
As used herein, the terms “slightly soluble” and “soluble” refer to those having a relatively high dissolution rate as “soluble” for convenience when immersed in the same roughening solution for the same time. The slow one is called “slightly soluble” for convenience.
[0098]
The heat resistant resin matrix is preferably one that can maintain the shape of the roughened surface when the roughened surface is formed on the interlayer resin insulating layer using the roughening liquid, for example, a thermosetting resin, a thermoplastic resin. Examples thereof include resins and composites thereof. Further, by using a photosensitive resin, the via hole opening may be formed in the interlayer resin insulating layer by exposure and development processing.
[0099]
Examples of the thermosetting resin include an epoxy resin, a phenol resin, a polyimide resin, a polyolefin resin, and a fluororesin. Moreover, when sensitizing the said thermosetting resin, methacrylic acid, acrylic acid, etc. are used, and a thermosetting group is (meth) acrylated. In particular, (meth) acrylate of epoxy resin is desirable. Furthermore, an epoxy resin having two or more epoxy groups in one molecule is more desirable. Not only can the above-mentioned roughened surface be formed, but also has excellent heat resistance, etc., so that stress concentration does not occur in the conductor circuit even under heat cycle conditions, and the conductor circuit and the interlayer resin insulation layer Peeling hardly occurs between
[0100]
Examples of the thermoplastic resin include polyether sulfone, polysulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenyl ether, polyether imide, and the like. These may be used alone or in combination of two or more.
[0101]
The substance soluble in the roughening liquid consisting of at least one selected from the acid, alkali and oxidizing agent is at least one selected from inorganic particles, resin particles, metal particles, rubber particles, liquid phase resin and liquid phase rubber. It is desirable to be a seed.
[0102]
Examples of the inorganic particles include aluminum compounds, calcium compounds, potassium compounds, magnesium compounds, and silicon compounds. These may be used alone or in combination of two or more.
[0103]
Examples of the aluminum compound include alumina and aluminum hydroxide. Examples of the calcium compound include calcium carbonate and calcium hydroxide. Examples of the potassium compound include potassium carbonate. Examples of the magnesium compound include magnesia, dolomite, basic magnesium carbonate, and talc. Examples of the silicon compound include silica and zeolite. These may be used alone or in combination of two or more.
[0104]
The alumina particles can be dissolved and removed with hydrofluoric acid, and calcium carbonate can be dissolved and removed with hydrochloric acid. Sodium-containing silica and dolomite can be dissolved and removed with an alkaline aqueous solution.
[0105]
Examples of the resin particles include those made of a thermosetting resin, a thermoplastic resin, and the like. When the resin particles are immersed in a roughening solution made of at least one selected from an acid, an alkali, and an oxidizing agent, the heat resistance It is not particularly limited as long as it has a faster dissolution rate than the resin matrix. Specifically, for example, amino resins (melamine resins, urea resins, guanamine resins, etc.), epoxy resins, phenol resins, phenoxy resins, polyimide resins, Examples include polyphenylene resin, polyolefin resin, fluororesin, and bismaleimide-triazine resin. These may be used alone or in combination of two or more.
[0106]
In addition, the said epoxy resin can be arbitrarily manufactured by selecting what kind of oligomer and hardening | curing agent what melt | dissolves in an acid and an oxidizing agent, and a thing hardly soluble in these. For example, a resin obtained by curing a bisphenol A type epoxy resin with an amine curing agent dissolves very well in chromic acid, but a resin obtained by curing a cresol novolac type epoxy resin with an imidazole curing agent is difficult to dissolve in chromic acid. .
[0107]
The resin particles must be previously cured. If not cured, the resin particles are dissolved in a solvent that dissolves the resin matrix, so they are uniformly mixed, and only the resin particles cannot be selectively dissolved and removed with an acid or an oxidizing agent. is there.
[0108]
Examples of the metal particles include gold, silver, copper, tin, zinc, stainless steel, aluminum, nickel, iron, lead, and the like. These may be used alone or in combination of two or more.
In addition, the metal particles may be coated with a resin or the like in order to ensure insulation.
[0109]
Examples of the rubber particles include acrylonitrile-butadiene rubber, polychloroprene rubber, polyisoprene rubber, acrylic rubber, polysulfuric rigid rubber, fluorine rubber, urethane rubber, silicone rubber, ABS resin, and the like.
[0110]
In addition, as the rubber particles, for example, polybutadiene rubber, various modified polybutadiene rubbers such as epoxy modification, urethane modification, (meth) acrylonitrile modification, (meth) acrylonitrile / butadiene rubber containing a carboxyl group, and the like can be used. By using these rubber particles, the rubber particles are easily dissolved in an acid or an oxidizing agent. That is, when dissolving rubber particles using an acid, an acid other than a strong acid can be dissolved. When dissolving rubber particles using an oxidizing agent, even permanganic acid having a relatively low oxidizing power can be used. Can be dissolved. Even when chromic acid is used, it can be dissolved at a low concentration. Therefore, no acid or oxidizing agent remains on the surface of the interlayer resin insulation layer, and as described later, when a catalyst such as palladium chloride is applied after the roughened surface is formed, the catalyst is not applied or the catalyst is not There is no oxidation. These may be used alone or in combination of two or more.
[0111]
When two or more kinds of the above-mentioned soluble substances are used in combination, the combination of the two kinds of soluble substances to be mixed is preferably a combination of resin particles and inorganic particles. Both of them have low conductivity, so that the insulation of the interlayer resin insulation layer can be secured, and the thermal expansion can be easily adjusted between the poorly soluble resin and the interlayer resin comprising the roughened surface forming resin composition This is because no crack occurs in the insulating layer, and no peeling occurs between the interlayer resin insulating layer and the upper conductor circuit.
[0112]
As the liquid phase resin, an uncured solution of the thermosetting resin can be used. As a specific example of such a liquid phase resin, for example, a mixed liquid of an uncured epoxy oligomer and an amine curing agent. Etc.
Examples of the liquid phase rubber include various polybutadiene rubbers such as the above polybutadiene rubber, epoxy modification, urethane modification, (meth) acrylonitrile modification, uncured solutions such as (meth) acrylonitrile / butadiene rubber containing a carboxyl group, etc. Can be used.
[0113]
When preparing the photosensitive resin composition using the liquid phase resin or liquid phase rubber, so that the heat resistant resin matrix and the soluble substance are not compatible with each other uniformly (that is, so as to phase-separate), It is necessary to select these substances.
By mixing the heat-resistant resin matrix selected according to the above criteria and a soluble substance, the liquid-phase resin or liquid-phase rubber “islands” are dispersed in the “sea” of the heat-resistant resin matrix. Alternatively, it is possible to prepare a photosensitive resin composition in which “islands” of a heat-resistant resin matrix are dispersed in a “sea” of a liquid phase resin or a liquid phase rubber.
[0114]
And after hardening the photosensitive resin composition of such a state, a roughened surface can be formed by removing the liquid phase resin or liquid phase rubber of "the sea" or "the island".
[0115]
Examples of the acid used as the roughening solution include phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, and organic acids such as formic acid and acetic acid. Among these, it is desirable to use an organic acid. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded.
As the oxidizing agent, for example, an aqueous solution of chromic acid, chromium sulfuric acid, alkaline permanganate (such as potassium permanganate), or the like is preferably used.
Moreover, as said alkali, aqueous solution, such as sodium hydroxide and potassium hydroxide, is desirable.
[0116]
The average particle size of the soluble substance is desirably 10 μm or less.
Further, a relatively large coarse particle having an average particle diameter of 2 μm or less and a fine particle having a relatively small average particle diameter may be used in combination. That is, a soluble substance having an average particle diameter of 0.1 to 0.5 μm and a soluble substance having an average particle diameter of 1 to 2 μm are combined.
[0117]
Thus, by combining average particles, relatively large coarse particles, and fine particles having a relatively small average particle diameter, the dissolution residue of the electroless plating film is eliminated, and the amount of palladium catalyst under the plating resist is reduced. Furthermore, a shallow and complicated roughened surface can be formed.
Furthermore, by forming a complicated roughened surface, a practical peel strength can be maintained even if the roughened surface has small irregularities.
The coarse particles preferably have an average particle size of more than 0.8 μm and less than 2.0 μm, and the fine particles preferably have an average particle size of 0.1 to 0.8 μm.
[0118]
By combining the coarse particles and fine particles, a shallow and complicated roughened surface can be formed. If the particle size used is coarse particles and the average particle size is less than 2 μm, these particles are dissolved and removed. However, the anchor formed is shallow, and the removed particles are a mixture of coarse particles having a relatively large particle size and fine particles having a relatively small particle size. Is complicated. By forming such a complicated roughened surface, a practical peel strength can be maintained even on a shallow roughened surface.
[0119]
Also, in this case, if the particle size used is coarse particles and the average particle size is less than 2 μm, roughening does not proceed excessively and voids are not generated, and the formed interlayer resin insulation layer is excellent in interlayer insulation. ing.
In the roughened surface forming resin composition, the particle size of the soluble substance is the length of the longest part of the soluble substance.
[0120]
Further, when the coarse particles have an average particle size of more than 0.8 μm and less than 2.0 μm, and the fine particles have an average particle size of 0.1 to 0.8 μm, the depth of the roughened surface is approximately Rmax = 3 μm. In the semi-additive method, not only the electroless plating film can be easily removed by etching, but also the palladium catalyst under the electroless plating film can be easily removed, and a practical peel strength of 1.0 to 1.3 kg / cm can be maintained.
[0121]
The shape of the soluble substance is not particularly limited, and examples thereof include a spherical shape and a crushed shape. Moreover, it is desirable that the soluble substance has a uniform shape. This is because a roughened surface having unevenness with uniform roughness can be formed.
[0122]
The roughened surface-forming resin composition may contain an organic solvent so that it can be applied onto a substrate or the like, or is formed into a film so that it can be pressure-bonded onto the substrate or the like. (Hereinafter also referred to as a roughened surface-forming resin film).
When the roughened surface-forming resin composition contains an organic solvent, the content is desirably 10% by weight or less.
[0123]
In the roughened surface-forming resin film, it is desirable that the soluble substance is dispersed substantially uniformly in the heat-resistant resin matrix. A roughened surface having unevenness of uniform roughness can be formed, and even if a via hole or a through hole is formed in a resin film, adhesion with an upper layer conductor circuit formed thereon can be ensured. Because. Moreover, the said roughened surface formation resin film may be formed so that only a surface layer part which forms a roughened surface may contain a soluble substance. Thereby, since the surface layer portion other than the surface layer portion of the roughened surface-forming resin film is not exposed to the acid or the oxidizing agent, the insulation between the conductor circuits through the interlayer resin insulating layer is reliably maintained.
[0124]
In the roughened surface forming resin film, the blending amount of the soluble substance dispersed in the hardly soluble resin is preferably 3 to 40% by weight with respect to the roughened surface forming resin film. If the blending amount of the soluble substance is less than 3% by weight, a roughened surface having desired irregularities may not be formed. If it exceeds 40% by weight, the soluble substance is dissolved using an acid or an oxidizing agent. When it does, it melt | dissolves to the deep part of a resin film, cannot maintain the insulation between the conductor circuits through the interlayer resin insulation layer which consists of a resin film, and may cause a short circuit.
[0125]
The roughened surface-forming resin film desirably contains a curing agent, other components, etc. in addition to the soluble substance and the heat-resistant resin matrix.
Examples of the curing agent include imidazole curing agents, amine curing agents, guanidine curing agents, epoxy adducts of these curing agents, microcapsules of these curing agents, triphenylphosphine, and tetraphenylphosphorus. And organic phosphine compounds such as nium tetraphenylborate.
[0126]
As for content of the said hardening | curing agent, it is desirable that it is 0.05 to 10 weight% with respect to the resin film for roughening surface formation. If it is less than 0.05% by weight, the roughened surface-forming resin film is insufficiently cured, so that the degree of penetration of the acid or oxidizing agent into the roughened surface-forming resin film increases, and the roughened surface-forming resin The insulation of the film may be impaired. On the other hand, if it exceeds 10% by weight, an excessive curing agent component may denature the composition of the resin, which may lead to a decrease in reliability.
[0127]
Examples of the other components include fillers such as inorganic compounds or resins that do not affect the formation of the roughened surface. Examples of the inorganic compound include silica, alumina, and dolomite. Examples of the resin include polyimide resin, polyacrylic resin, polyamideimide resin, polyphenylene resin, melanin resin, and olefin resin. By containing these fillers, it is possible to improve the performance of the printed wiring board by matching the thermal expansion coefficient, improving heat resistance, and chemical resistance.
[0128]
Moreover, the said resin film for roughening surface formation may contain the solvent. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and aromatic hydrocarbons such as ethyl acetate, butyl acetate, cellosolve acetate, toluene, and xylene. These may be used alone or in combination of two or more.
[0129]
(5) Next, when forming an interlayer resin insulation layer using a thermosetting resin or resin composite as the material, the uncured resin insulation layer is cured and a via hole opening is formed. And an interlayer resin insulation layer. In this step, a through hole may be formed as necessary.
The via hole opening is preferably formed by laser processing. The laser treatment may be performed before the curing treatment or after the curing treatment.
When an interlayer resin insulating layer made of a photosensitive resin is formed, a via hole opening may be provided by performing exposure and development processes. In this case, the exposure and development processes are performed before the curing process.
[0130]
When an interlayer resin insulation layer using a thermoplastic resin as the material is formed, a via hole opening can be formed in the resin layer made of the thermoplastic resin by laser processing to form an interlayer resin insulation layer. .
[0131]
At this time, examples of the laser to be used include a carbon dioxide laser, an excimer laser, a UV laser, and a YAG laser.
These lasers may be selectively used in consideration of the via hole opening to be formed, the shape of the through hole, and the like.
[0132]
In the case of forming the via hole openings, a large number of via hole openings can be formed at a time by irradiating laser light with a hologram type excimer laser through a mask.
In addition, when a via hole opening is formed using a short pulse carbon dioxide laser, there is little resin residue in the opening, and damage to the resin at the periphery of the opening is small.
[0133]
In addition, by irradiating laser light through an optical system lens and a mask, a large number of openings for via holes can be formed at one time.
This is because laser light having the same intensity and the same irradiation angle can be simultaneously irradiated to a plurality of portions through the optical system lens and the mask.
[0134]
The through hole formed in the mask is preferably a perfect circle in order to make the spot shape of the laser beam a perfect circle, and the diameter of the through hole is preferably about 0.1 to 2 mm.
When the carbon dioxide laser is used, the pulse interval is 10^-Four-10^-8It is desirable to be seconds. Moreover, it is desirable that the time for irradiating the laser for forming the opening is 10 to 500 μsec.
[0135]
When the via hole opening is formed by laser light, especially when a carbon dioxide laser is used, it is desirable to perform desmear treatment. The desmear treatment can be carried out using an oxidizing agent comprising an aqueous solution such as chromic acid or permanganate. Oxygen plasma, CF_Four And may be treated with a mixed plasma of oxygen and oxygen, corona discharge, or the like. Further, the surface can be modified by irradiating with ultraviolet rays using a low-pressure mercury lamp.
[0136]
Although the thickness of the said interlayer resin insulation layer is not specifically limited, 5-50 micrometers is desirable.
If the thickness is less than 5 μm, insulation between adjacent conductor circuits may not be maintained. On the other hand, if the thickness exceeds 50 μm, the resin remains on the bottom when via holes are formed. Or the shape of the via hole opening or the like may be tapered toward the bottom.
Moreover, the opening diameter of the opening for the via hole is not particularly limited, but is usually preferably 40 to 200 μm.
[0137]
Moreover, when forming a through-hole in the board | substrate with which the interlayer resin insulation layer was formed, a through-hole is formed using a 50-300 micrometers diameter drill, a laser beam, etc.
In the case where the through hole is formed, a through layer can be formed by forming a conductor layer on the inner wall surface of the through hole in a step to be described later. By forming the through hole, the substrate and the interlayer resin can be formed. Conductor circuits can be electrically connected via the insulating layer.
[0138]
(6) Next, if necessary, an acid or an oxidizing agent is used for the surface of the interlayer resin insulating layer including the inner wall of the opening for the via hole and the inner wall of the through hole when the through hole is formed in the above process. To form a roughened surface.
Examples of the acid include sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, formic acid, and examples of the oxidizing agent include permanganates such as chromic acid, chromium sulfuric acid, and sodium permanganate.
In addition, the roughened surface may be formed using plasma treatment or the like.
[0139]
Specifically, when the interlayer resin insulation layer is formed using a roughened surface forming resin composition or the like, it is desirable to form a roughened surface using an acid or an oxidizing agent, In the case of using it, it is desirable to form a roughened surface using plasma treatment or the like.
[0140]
This roughened surface is formed in order to improve the adhesion between the interlayer resin insulation layer and the electroless plating film formed thereon, and is sufficient between the interlayer resin insulation layer and the electroless plating film. If it has good adhesion, it does not have to be formed.
[0141]
After that, when the roughened surface is formed using acid, an aqueous solution such as an alkali is used, and when the roughened surface is formed using an oxidizing agent, the inside of the via hole or the through hole is formed using a neutralizing solution. Neutralize. By this operation, acid and oxidant are removed so as not to affect the next process.
[0142]
(7) Next, if necessary, a catalyst is applied to the formed roughened surface. Examples of the catalyst include palladium as described above.
At this time, in order to reliably apply the catalyst, dry treatment such as plasma treatment of oxygen, nitrogen, etc. and corona treatment removes the residue of acid or oxidant and reforms the surface of the interlayer resin insulation layer By doing so, it is possible to reliably provide a catalyst and improve the metal deposition during electroless plating and the adhesion of the electroless plating layer to the interlayer resin insulation layer. In this case, a great effect can be obtained.
[0143]
(8) Next, a thin film conductor layer is formed on the surface of the interlayer resin insulation layer including the inner wall surface of the via hole opening.
The thin film conductor layer can be formed using a method such as electroless plating, sputtering, or vapor deposition.
Moreover, when the roughening surface is not formed in the said interlayer resin insulation layer, it is desirable to form the said thin film conductor layer by sputtering.
[0144]
The method for forming the thin film conductor layer is preferably selected according to the material of the interlayer resin insulation layer.
Specifically, when the thin film conductor layer is formed on the interlayer resin insulating layer made of the rough surface-forming resin composition, it is desirable to form the thin film conductor layer by electroless plating, and the thickness is 0.6 to 1.2 μm. Is desirable.
In this case, it is desirable to pre-process the interlayer resin insulation layer using the above-described pre-treatment liquid for electroless plating.
Moreover, when forming a thin film conductor layer in the interlayer resin insulation layer which consists of low dielectric resin films, such as polyolefin resin, it is desirable to form by sputtering and vapor deposition, and the thickness is desirable to be 0.1-1.0 micrometer. . The thin film conductor layer formed at this time is preferably composed of two layers of nickel and copper. Further, a layer made of electroless plating may be formed on the thin film conductor layer formed by sputtering or the like.
[0145]
When the through hole is formed in the step (5), a through hole may be formed by forming a thin film conductor layer made of metal on the inner wall surface of the through hole in this step.
When a through hole is formed in the step (8), it is desirable to perform the following processing steps. That is, the surface of the electroless plating layer and the inner wall of the through hole are subjected to a roughening process using a blackening (oxidation) -reduction process, an etching process, a Cu-Ni-P acicular alloy plating process, or the like. Thereafter, the inside of the through hole is further filled with a resin filler or the like, and then the surface layer portion of the resin filler and the surface of the electroless plating film are planarized using a polishing method such as buffing.
Furthermore, electroless plating is performed, and an electroless plating layer is formed on the electroless plating film already formed and the surface layer portion of the resin filler, thereby forming a lid plating layer on the through hole. In this case as well, it is desirable to pretreat the object to be plated such as the surface layer portion of the resin filler using the above-described pretreatment liquid for electroless plating.
[0146]
(9) Next, a plating resist is formed using a dry film on a part of the interlayer resin insulation layer on which the thin film conductor layer is formed, and then electroplating is performed using the thin film conductor layer as a plating lead. An electrolytic plating layer is formed on the plating resist non-forming portion.
At this time, the via hole opening may be filled with electrolytic plating to form a field via structure, or after filling the via hole opening with a conductive paste or the like, a lid plating layer is formed thereon to form the field via structure. Good. By forming the field via structure, a via hole can be formed immediately above the via hole.
[0147]
(10) After forming the electrolytic plating layer, the plating resist is peeled off, and the thin film conductor layer made of metal existing under the plating resist is removed by etching to form an upper-layer conductor circuit of an independent pattern.
As the etching solution, for example, sulfuric acid / hydrogen peroxide solution, ferric chloride, cupric chloride, persulfate aqueous solution such as ammonium persulfate, hydrochloric acid, nitric acid, hot dilute sulfuric acid and the like can be used. Further, the electroless plating film may be removed using an etching solution containing a cupric complex and an organic acid, and a roughened surface may be formed on the surface of the upper conductor circuit.
Furthermore, if necessary, the catalyst on the interlayer resin insulating layer may be removed using an acid or an oxidizing agent. By removing the catalyst, the metal such as palladium used for the catalyst is eliminated, so that deterioration of electrical characteristics can be prevented.
[0148]
(11) Next, if necessary, after roughening the upper layer conductor circuit by the same method as described in (2), the steps (4) to (10) are repeated to obtain the lower layer conductor circuit. It is possible to manufacture a substrate in which an interlayer resin insulation layer and an upper conductor circuit are sequentially laminated on the substrate on which the is formed.
[0149]
(12) Next, a solder resist layer is formed on the substrate surface including the upper-layer upper-layer conductor circuit. Further, the solder resist layer is opened to form a solder pad, and then the solder pad is filled with the solder paste. Then, solder bumps are formed by reflowing. After that, by arranging pins or forming solder balls on the connection surface of the external substrate, a PGA (Pin Grid Array) or BGA (Ball Grid Array) is obtained.
[0150]
The solder resist layer can be formed using, for example, a solder resist composition comprising a polyphenylene ether resin, a polyolefin resin, a fluororesin, a thermoplastic elastomer, an epoxy resin, a polyimide resin, and the like. For example, the same resin as the resin used for the interlayer resin insulating layer can be used.
[0151]
Examples of solder resist compositions other than those described above include, for example, (meth) acrylates of novolak epoxy resins, imidazole curing agents, bifunctional (meth) acrylic acid ester monomers, and (meth) acrylic acid having a molecular weight of about 500 to 5,000. Examples include paste polymers containing ester polymers, thermosetting resins composed of bisphenol-type epoxy resins, photosensitive monomers such as polyvalent acrylic monomers, glycol ether solvents, and the viscosity at 25 ° C. It is desirable that the pressure is adjusted to 1 to 10 Pa · s.
Examples of the (meth) acrylate of the novolak type epoxy resin include an epoxy resin obtained by reacting a glycidyl ether of phenol novolak or cresol novolak with acrylic acid or methacrylic acid.
[0152]
The bifunctional (meth) acrylic acid ester monomer is not particularly limited, and examples thereof include acrylic acid and methacrylic acid esters of various diols, and commercially available products thereof include R- manufactured by Nippon Kayaku Co., Ltd. 604, PM2, PM21 and the like.
[0153]
The solder resist composition may contain an elastomer or an inorganic filler.
When the elastomer is blended, the formed solder resist layer absorbs or relieves stress even when stress acts on the solder resist layer due to the flexibility and rebound resilience of the elastomer. As a result, it is possible to suppress the occurrence of cracks and peeling in the solder resist layer after mounting electronic components such as IC chips on the manufacturing process of the multilayer printed wiring board and the manufactured multilayer printed wiring board. Even when this occurs, the crack cannot grow greatly.
Examples of the method of opening the solder resist layer include a method of irradiating a laser beam as in the method of forming a via hole opening.
[0154]
In addition, when a photosensitive solder resist composition is used as the solder resist composition, after forming the solder resist layer, the photoresist is placed on the solder resist layer and subjected to exposure and development treatment. The solder resist layer can be opened.
[0155]
The upper conductor circuit portion exposed by opening the solder resist layer is usually preferably coated with a corrosion-resistant metal such as nickel, palladium, gold, silver, or platinum. Specifically, it is desirable to form the coating layer with a metal such as nickel-gold, nickel-silver, nickel-palladium, nickel-palladium-gold.
The coating layer can be formed by, for example, plating, vapor deposition, electrodeposition, or the like, and among these, plating is desirable from the viewpoint of excellent uniformity of the coating layer.
In addition, plasma treatment with oxygen, carbon tetrachloride, or the like may be performed in a timely manner for a character printing process for forming product recognition characters or the like or for modifying the solder resist layer.
[0156]
Next, the manufacturing method of the multilayer printed wiring board of 2nd this invention is demonstrated.
According to a second method of manufacturing a multilayer printed wiring board of the present invention, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated on a substrate on which a lower layer conductor circuit is formed, and these conductor circuits are connected via via holes. It is a manufacturing method of the multilayer printed wiring board connected, Comprising: The process of forming the lower layer conductor circuit of the following (a)-(g) is included at least.
(A) forming a metal layer on the substrate;
(B) a step of sequentially performing an opening formation process on the metal layer and the substrate, and forming a through hole in the substrate on which the metal layer is formed by the opening formation process;
(C) Before electroless plating comprising an aqueous solution containing 0.01 to 0.25 mol / l of an alkaline compound and 0.1 to 0.3 mol / l of a reducing agent on the substrate on which the through hole is formed. A step of performing a pretreatment using a treatment liquid;
(D) a step of forming an electroless plating film on the surface of the substrate that has been subjected to the pretreatment;
(E) forming an electrolytic plating film on the electroless plating film;
(F) forming an etching resist on a part of the electrolytic plating film; and
(G) A step of removing the electrolytic plating film, the electroless plating film, and the metal layer under the non-forming portion of the etching resist by an etching process.
[0157]
According to the method for producing a multilayer printed wiring board of the second aspect of the present invention, before performing the electroless plating process for forming the lower layer conductor circuit on the substrate including the through hole, the multilayer printed wiring of the first aspect of the present invention is performed. Using a pretreatment liquid similar to the pretreatment liquid for electroless plating used in the plate manufacturing method, the substrate with through-holes is pretreated, so the electroless plating process has excellent adhesion to the substrate. A uniform electroless plating film can be formed, and as a result, a multilayer printed wiring board excellent in connection reliability and electrical characteristics can be manufactured.
[0158]
The method for producing a multilayer printed wiring board according to the second aspect of the present invention (hereinafter also simply referred to as the second production method) is compared with the first production method in steps (d) to (g), ie, pretreatment. After forming the electroless plating film on the surface of the substrate subjected to the above, only the step of forming the lower layer conductor circuit on the substrate through the electrolytic plating process is different. Therefore, in the second manufacturing method, only the steps (d) to (g) will be described in detail, and the other manufacturing steps will be described briefly.
[0159]
First, the steps (a) to (g) in the second production method will be described.
In the second manufacturing method, similar to the steps (a) to (d) in the first manufacturing method, the surface of the substrate that has been pretreated, that is, the wall surface of the through-hole and the metal layer on the substrate An electroless plating film is formed on the surface (steps (a) to (d)).
[0160]
Next, an electrolytic plating film is formed on the electroless plating film formed in the above steps (a) to (d) (step (e)).
The electrolytic plating film can be formed by using the electroless plating film already formed as a plating lead.
Specifically, for example, an electrolytic copper plating film can be formed by using an electrolytic plating solution containing sulfuric acid, copper sulfate and an additive.
[0161]
Next, an etching resist is formed on a portion of the electrolytic plating film, that is, a portion corresponding to the lower conductor circuit formation portion (step (f)).
The etching resist can be formed, for example, by applying a photosensitive dry film or applying a liquid resist and then performing an exposure development process.
[0162]
Next, by performing an etching process, the electrolytic plating film, the electroless plating film, and the metal layer under the etching resist non-forming portion are removed (step (g)). Thereafter, the etching resist is removed using a strong alkaline aqueous solution or the like.
Here, examples of the etching solution used for removing the electroless plating film and the metal layer include a sulfuric acid-hydrogen peroxide aqueous solution, a persulfate aqueous solution such as ammonium persulfate and potassium persulfate, ferric chloride, and cupric chloride. And an etching solution containing a cupric complex and an organic acid.
Further, physical etching such as ion beam etching may be used.
In consideration of the material of the electrolytic plating film, the electroless plating film, the metal layer, and the like, the etching solution used for each removal may be properly used.
[0163]
Through the steps (a) to (g), a lower layer conductor circuit (including through holes) can be formed on the substrate.
Further, in the method for producing a multilayer printed wiring board according to the second aspect of the present invention, before forming the electroless plating film, for the through hole formed on the substrate using the electroless plating pretreatment liquid having the above composition. Since the pretreatment is applied to the wall surface of the through hole, a lower layer conductor circuit having excellent adhesion to the substrate can be formed.
[0164]
In the second production method, first, a substrate on which a lower layer conductor circuit and a through hole are formed by passing through the steps (a) to (g) described above, and then the first production method ( A multilayer printed wiring board can be manufactured by using the same method as in steps 2) to (12).
[0165]
Next, the manufacturing method of the multilayer printed wiring board of 3rd this invention is demonstrated.
According to a third method of manufacturing a multilayer printed wiring board of the present invention, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated on a substrate on which a lower layer conductor circuit is formed, and these conductor circuits are connected via via holes. It is a manufacturing method of the multilayer printed wiring board connected, Comprising: The process of forming the upper layer conductor circuit of the following (A)-(G) is included at least.
(A) forming a resin / metal layer composed of a resin layer and a metal layer on the lower conductor circuit or the upper conductor circuit;
(B) A step of sequentially performing an opening forming process on the resin layer and the metal layer constituting the resin / metal layer to form a via hole opening;
(C) A pretreatment liquid for electroless plating comprising an aqueous solution containing 0.01 to 0.25 mol / l of an alkaline compound and 0.1 to 0.3 mol / l of a reducing agent on the resin / metal layer. The step of applying the pretreatment used,
(D) a step of forming an electroless plating film on the surface of the resin / metal layer subjected to the pretreatment;
(E) forming a plating resist on a part of the electroless plating film;
(F) forming an electrolytic plating film on the plating resist non-forming portion; and
(G) A step of removing the electroless plating film and the metal layer under the plating resist after peeling off the plating resist.
[0166]
According to the method for producing a multilayer printed wiring board of the third aspect of the present invention, before the electroless plating treatment for forming the upper layer conductor circuit including the via hole is performed on the interlayer resin insulating layer, the first aspect of the present invention is provided. In order to pre-treat the wall surface of the opening for the via hole using the same pre-treatment liquid as the pre-treatment liquid for electroless plating used in the method for manufacturing a multilayer printed wiring board, an interlayer resin insulation layer is obtained by electroless plating. A uniform electroless plating film having excellent adhesion to the substrate can be formed. As a result, a multilayer printed wiring board having excellent connection reliability and electrical characteristics can be produced.
[0167]
The method for producing a multilayer printed wiring board according to the third aspect of the present invention (hereinafter also simply referred to as a third production method) differs from the first production method in steps (A) to (G). That is, the first manufacturing method is characterized by the step of forming the lower layer conductor circuit on the substrate, whereas the third manufacturing method is the step of forming the upper layer conductor circuit on the interlayer resin insulating layer. It has the characteristics. However, in both of these manufacturing methods, there is no significant difference in the technical idea in forming a conductor circuit having a suitable shape and characteristics, and only the manufacturing process having features is different.
Therefore, in the following description of the third manufacturing method, the manufacturing process will be described in detail, and the actions, effects, etc. in this manufacturing method will be described briefly.
[0168]
As described above, the third manufacturing method is characterized by the steps (A) to (G), that is, the step of forming the upper conductor circuit on the interlayer resin insulation layer. Steps A) to (G) will be described, and all manufacturing steps for manufacturing a multilayer printed wiring board will be described later.
[0169]
In the third manufacturing method, by performing steps (A) to (G), an upper layer conductor circuit including a through hole is formed on the interlayer resin insulating layer. In addition, when the processes (A) to (G) are performed on the upper layer conductor circuit formed on the interlayer resin insulation layer, a plurality of interlayer resin insulation layers and upper layer conductor circuits are formed. .
In the third production method, a resin / metal layer composed of a resin layer and a metal layer is formed on a lower conductor circuit formed on a substrate or an upper conductor circuit formed on an interlayer resin insulation layer (step ( A)).
The resin / metal layer may be formed by laminating a resin on a conductor circuit (a lower layer conductor circuit or an upper layer conductor circuit) and then laminating a metal, or a so-called bonding of a resin and a metal. After forming the metal foil with resin, it may be laminated.
[0170]
When laminating a resin on a conductor circuit and then laminating a metal, first, an uncured resin layer made of a thermosetting resin or a resin composite is formed on the conductor circuit, or a thermoplastic resin. A resin layer made of is formed. Specifically, a method similar to the step (4) described in the first manufacturing method can be used.
Moreover, as a thermosetting resin, a resin composite, and a thermoplastic resin, the thing similar to what was used by the 1st manufacturing method can be used.
The uncured resin layer made of the thermosetting resin or resin composite may be cured immediately after lamination, or may be cured after forming a metal layer in a process described later.
[0171]
Next, a metal layer is formed on the resin layer.
The metal layer can be formed using physical vapor deposition such as sputtering or vacuum vapor deposition, or chemical vapor deposition.
Examples of the material for the metal layer include copper, nickel, aluminum, chromium, iron, noble metals (gold, silver, palladium, platinum), and the thickness thereof is 0.1 to 2.0 μm. desirable.
In addition, the said metal layer may consist of one layer, and may consist of two or more layers.
In addition, when the metal layer is formed by electroless plating, the resin layer is pretreated using an electroless plating pretreatment solution used in Step C described later before performing the electroless plating. May be.
[0172]
Moreover, when laminating a metal foil with resin on a conductor circuit, for example, the metal foil with resin can be laminated on the conductor circuit by vacuum pressing.
At this time, the conditions of the vacuum press are not particularly limited, and may be appropriately selected in consideration of the material, shape and the like of the resin-coated metal foil. For example, the temperature is 150 to 180 ° C, the pressure is 2 to 4 MPa, and the time is 30 to 90. Min, the degree of vacuum can be 10 kPa or less.
In addition, formation of the said metal foil with resin can be performed by a conventionally well-known method, and a commercially available metal foil with resin can also be used.
[0173]
Next, an opening forming process is sequentially performed on the resin layer and the metal layer constituting the resin / metal layer, and a via hole opening is formed by the opening forming process (step (B)).
That is, first, an opening is formed in the metal layer formed in the metal layer, and then an opening is formed in the resin layer below the opening formed in the metal layer to form a via hole opening.
[0174]
As a method for forming the opening in the metal layer, for example, the following method can be used.
That is, an opening can be formed by forming an etching resist on a part of the metal layer and then performing etching.
In addition, formation of an etching resist and an etching process can be performed using the method similar to the method used at the process of (b) in a 1st manufacturing method.
[0175]
In this step, it is desirable to adjust the thickness of the metal layer to about 0.5 to 5 μm before forming the opening in the metal layer. If the thickness of the metal layer is less than 0.5 μm, the metal layer may not be able to serve as a conformal mask when a through hole is formed in the substrate in a later process. When the thickness exceeds 5 μm, the shape of the via hole opening may not be a desired shape when the via hole opening is formed by laser processing.
In addition, adjustment of the thickness of the said metal layer can be performed by an etching process etc., for example.
[0176]
Next, the etching resist is removed, and an opening is formed in the resin layer using the metal layer having the opening as a conformal mask to form a via hole opening.
The opening can be formed by laser processing or the like, for example.
At this time, examples of the laser to be used include a carbon dioxide laser, an excimer laser, a UV laser, and a YAG laser.
These lasers may be properly used in consideration of the shape of the opening to be formed.
Further, it is desirable that the beam diameter at the time of laser processing is 1.3 times or more the diameter of the opening to be formed. This is because an opening having a desired shape can be formed.
[0177]
After the laser treatment, the resin residue in the via hole opening may be removed.
The resin residue can be removed by, for example, immersing a substrate having a via hole opening in an aqueous solution of chromic acid, permanganic acid, potassium, or the like.₂ Plasma, CF_Four Plasma, O₂ And CF_Four It can be performed by plasma treatment with a plasma of a mixed gas.
[0178]
Next, a pretreatment liquid for electroless plating comprising an aqueous solution containing 0.01 to 0.25 mol / l of an alkaline compound and 0.1 to 0.3 mol / l of a reducing agent is applied to the resin / metal layer. The pretreatment used is performed (step (C)).
Further, before the pretreatment, it is desirable that a catalyst such as palladium metal is provided in advance on the surface of the resin / metal layer in which the opening for the via hole is formed.
The application of the catalyst can be performed by the same method as the first production method.
[0179]
In this step, the same pretreatment solution for electroless plating as that used in the step (c) of the first production method is used.
By using such a pretreatment liquid for electroless plating, the catalyst can be sufficiently activated by performing the pretreatment, and as a result, when performing the electroless plating treatment in a subsequent step, An electroless plating film excellent in adhesion can be formed. The reason for this is as described in the explanation of the first manufacturing method.
[0180]
The pretreatment is performed by immersing a substrate having a via hole opening formed in the resin / metal layer in the pretreatment liquid for electroless plating.
The pretreatment conditions at this time are the same as the pretreatment conditions in the first manufacturing method, that is, the temperature of the pretreatment liquid for electroless plating is 20 to 50 ° C., and the pretreatment time is 0. Desirably, 5 to 5 minutes.
[0181]
Next, an electroless plating film is formed on the surface of the pretreated resin / metal layer, that is, the wall surface of the via hole opening and the surface of the metal layer on the substrate (step (D)).
The electroless plating film is formed by immersing the substrate on which the via hole opening is formed in an electroless plating solution.
[0182]
Although it does not specifically limit as said electroless-plating liquid, What consists of the aqueous solution containing the alkaline compound similar to a 1st manufacturing method, a reducing agent, copper ion, and tartaric acid or its salt is preferable. The reason for this is as described in the explanation of the first manufacturing method.
The conditions for electroless plating are also the same as in the first production method, that is, the temperature of the electroless plating solution is 25 to 35 ° C. and the immersion time is preferably 10 to 20 minutes.
[0183]
Next, a plating resist is formed on a part of the electroless plating film formed in the step (D), that is, a portion corresponding to the upper conductor circuit non-forming portion (step (E)).
The plating resist can be formed, for example, by applying a photosensitive dry film or applying a liquid resist and then performing an exposure development process.
[0184]
Next, an electrolytic plating film is formed on the plating resist non-forming portion (step (F)).
The electrolytic plating film can be formed by using the already formed electroless plating film as a plating lead.
Specifically, for example, an electrolytic copper plating film can be formed by using an electrolytic plating solution containing sulfuric acid, copper sulfate and an additive.
[0185]
Next, the plating resist is peeled off, and then the electroless plating film and the metal layer under the plating resist are removed by an etching process (step (G)).
The said etching process can be performed using the thing similar to the etching liquid used at the process of (g) of a 1st manufacturing method.
[0186]
Through the steps (A) to (G), an interlayer resin insulating layer and an upper layer conductor circuit (including via holes) can be laminated on the lower layer conductor circuit or the upper layer conductor circuit.
In addition, in the method for producing a multilayer printed wiring board according to the third aspect of the present invention, before forming the electroless plating film, a pretreatment liquid for electroless plating having the above composition is used to form the wall surface of the opening for via holes and the metal. Since the surface of the layer is pretreated, an upper layer conductor circuit (including a via hole) having excellent adhesion to the interlayer resin insulating layer can be formed.
[0187]
Next, all manufacturing steps of the third manufacturing method will be described in the order of steps.
(1) In the third manufacturing method, first, a substrate having a lower layer conductor circuit formed on the surface of an insulating substrate is produced.
The insulating substrate is preferably a resin substrate, specifically, a glass epoxy substrate, a polyester substrate, a polyimide substrate, a bismaleimide-triazine resin substrate, a thermosetting polyphenylene ether substrate, a fluororesin substrate, a copper clad laminate, An RCC board etc. are mentioned.
At this time, if necessary, a through hole may be provided in the insulating substrate. In this case, the through-hole is desirably formed using a drill having a diameter of 100 to 300 μm, a laser beam, or the like.
[0188]
(2) Next, after applying electroless plating, an etching resist having a lower conductor circuit shape is formed on the substrate, and etching is performed to form a lower conductor circuit. As electroless plating, copper plating is desirable. In addition, when a through hole is provided in the insulating substrate, the wall surface of the through hole is simultaneously subjected to electroless plating to form a through hole, thereby electrically connecting the lower conductor circuits on both sides of the substrate. May be.
In addition, when performing electroless plating on an insulating substrate, it is desirable to perform pretreatment on the surface of the insulating substrate using the above-described pretreatment liquid for electroless plating.
Moreover, you may use the board | substrate with which the lower-layer conductor circuit (including a through hole) manufactured by passing through the process of (a)-(g) of a 1st or 2nd manufacturing method was formed.
[0189]
(3) Next, if necessary, the inner wall of the through hole and the surface of the lower conductor circuit are roughened. Examples of the roughening treatment method include blackening (oxidation) -reduction treatment, etching treatment, treatment with Cu—Ni—P needle-shaped alloy plating, and the like.
[0190]
Specific examples of the blackening (oxidation) -reduction treatment include NaOH (10 to 20 g / l), NaClO.₂ (40-50 g / l), Na_Three PO_Four Blackening treatment using an aqueous solution containing (6-15 g / l) as a blackening bath (oxidation bath), and NaOH (2.7-10 g / l), NaBH_Four Examples include a method of performing a reduction treatment using an aqueous solution containing (1.0 to 6.0 g / l) as a reduction bath.
[0191]
As an etching solution used for the etching treatment, a mixed solution of an organic acid and a cupric complex is desirable. Examples of the organic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, acrylic acid, crotonic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, benzoic acid, glycolic acid, Examples include lactic acid, malic acid, sulfamic acid and the like. These may be used alone or in combination of two or more. In the etching solution, the organic acid content is preferably 0.1 to 30% by weight. This is because the solubility of oxidized copper can be maintained and catalyst stability can be ensured.
[0192]
The cupric complex is preferably an azole cupric complex. This cupric complex of azoles acts as an oxidizing agent that oxidizes metallic copper and the like. Examples of azoles include diazole, triazole, and tetrazole. Among these, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and 2-undecylimidazole are desirable. In the etching solution, the content of the cupric complex is preferably 1 to 15% by weight. This is because it is excellent in solubility and stability and can also dissolve noble metals such as palladium constituting the catalyst core.
[0193]
Examples of the plating treatment include copper sulfate (1 to 40 g / l), nickel sulfate (0.1 to 6.0 g / l), citric acid (10 to 20 g / l), and sodium hypophosphite (10 to 10 g / l). 100 g / l), boric acid (10-40 g / l) and surfactant (manufactured by Nissin Chemical Industry Co., Surfinol 465) (0.01-10 g / l) in an electroless plating bath of pH = 9 And a method of forming a roughened layer made of a Cu-Ni-P alloy by electroless plating.
This is because the crystal structure of the plating film deposited in this range is a needle-like structure, which is excellent in anchor effect. In addition to the above compounds, complexing agents and additives may be added to the electroless plating bath.
[0194]
(4) Next, a resin filler is filled into the through hole. In addition, if necessary, the insulating substrate surface may be filled with a resin filler in a recess where the lower conductor circuit is not formed, and then the insulating substrate surface may be planarized by polishing or the like.
Thereafter, the resin filler is dried under conditions of, for example, 100 ° C./20 minutes, and then cured.
Curing is preferably performed at a temperature of 50 to 250 ° C. An example of the curing condition is a method of heating at 100 ° C. for 1 hour and then heating at 150 ° C. for 1 hour. As needed, you may perform step hardening which makes it harden | cure by changing high temperature and temperature from low temperature sequentially.
[0195]
In addition, when the surface of the insulating substrate including the surface of the lower conductor circuit is flattened by polishing, the lower conductor circuit may be roughened once more as necessary. Examples of the roughening treatment method include blackening (oxidation) -reduction treatment, etching treatment, treatment with Cu—Ni—P alloy plating, and the like.
[0196]
(5) Next, by performing the steps (A) to (G) described above, an interlayer resin insulating layer and an upper layer conductor circuit are formed on a substrate having a lower layer conductor circuit formed on the surface.
(6) Next, if necessary, the upper conductor circuit is roughened by the same method as described in (3) above, and then the above steps (A) to (G) are repeated to obtain a lower layer. A substrate in which an upper conductor circuit and an interlayer resin insulation are sequentially laminated on a substrate on which a conductor circuit is formed can be manufactured.
[0197]
(7) Next, a solder resist layer is formed on the surface of the substrate including the upper conductor circuit of the uppermost layer. Further, after opening the solder resist layer to form a solder pad, the solder pad is filled with the solder paste. Then, solder bumps are formed by reflowing. After that, by arranging pins or forming solder balls on the connection surface of the external substrate, a PGA (Pin Grid Array) or BGA (Ball Grid Array) is obtained.
The solder resist layer and the solder bump can be formed by the same method as that used in the first manufacturing method.
[0198]
Next, the manufacturing method of the multilayer printed wiring board of the 4th aspect of this invention is demonstrated.
According to a fourth method of manufacturing a multilayer printed wiring board of the present invention, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated on a substrate on which a lower layer conductor circuit is formed, and these conductor circuits are connected via via holes. It is a manufacturing method of the multilayer printed wiring board connected, Comprising: The process of forming the upper layer conductor circuit of the following (A)-(G) is included at least.
(A) forming a resin / metal layer composed of a resin layer and a metal layer on the lower conductor circuit or the upper conductor circuit;
(B) A step of sequentially performing an opening forming process on the resin layer and the metal layer constituting the resin / metal layer and forming an opening for a via hole by the opening forming process;
(C) A pretreatment liquid for electroless plating comprising an aqueous solution containing 0.01 to 0.25 mol / l of an alkaline compound and 0.1 to 0.3 mol / l of a reducing agent on the resin / metal layer. The step of applying the pretreatment used,
(D) a step of forming an electroless plating film on the surface of the pretreated resin / metal layer;
(E) forming an electrolytic plating film on the electroless plating film;
(F) forming an etching resist on a part of the electrolytic plating film; and
(G) A step of removing the etching resist from the electrolytic plating film, the electroless plating film, and the metal layer under the non-forming portion.
[0199]
According to the fourth method for producing a multilayer printed wiring board of the present invention, before performing an electroless plating process for forming an upper conductor circuit including a via hole on an interlayer resin insulating layer, the first present invention is provided. In order to pre-treat the wall surface of the opening for the via hole using the same pre-treatment liquid as the pre-treatment liquid for electroless plating used in the method for manufacturing a multilayer printed wiring board, an interlayer resin insulation layer is obtained by electroless plating. A uniform electroless plating film having excellent adhesion to the substrate can be formed. As a result, a multilayer printed wiring board having excellent connection reliability and electrical characteristics can be produced.
[0200]
The fourth method for manufacturing a multilayer printed wiring board of the present invention (hereinafter also simply referred to as the fourth manufacturing method) includes steps (D) to (G), that is, via holes, as compared with the third manufacturing method. The only difference is that the electroless plating film is formed on the surface of the resin / metal layer including the inner wall surface of the opening for forming, and then the upper conductor circuit is formed on the interlayer resin insulating layer through the electrolytic plating treatment. Accordingly, in the fourth manufacturing method, only the steps (D) to (G) will be described in detail, and the other manufacturing steps will be described briefly.
[0201]
First, the steps (A) to (G) in the fourth manufacturing method will be described.
In the fourth manufacturing method, an electroless plating film is formed on the surface of the resin / metal layer including the inner wall surface of the opening for the via hole, as in the steps (A) to (D) in the third manufacturing method. Form (steps (A) to (D)).
[0202]
Next, an electrolytic plating film is formed on the electroless plating film formed in the above steps (A) to (D) (step (E)).
The electrolytic plating film can be formed by using the electroless plating film already formed as a plating lead.
Specifically, for example, an electrolytic copper plating film can be formed by using an electrolytic plating solution containing sulfuric acid, copper sulfate and an additive.
[0203]
Next, an etching resist is formed on a portion of the electrolytic plating film, that is, a portion corresponding to the upper conductor circuit formation portion (step (F)).
The etching resist can be formed, for example, by applying a photosensitive dry film or applying a liquid resist and then performing an exposure development process.
[0204]
Next, the electrolytic plating film, the electroless plating film, and the metal layer under the etching resist non-forming portion are removed by performing an etching process (step (G)). Thereafter, the etching resist is removed using a strong alkaline aqueous solution or the like.
The said etching process can be performed using the method similar to the method used at the process of (g) in a 2nd manufacturing method.
[0205]
Through the steps (A) to (G), an interlayer resin insulating layer and an upper layer conductor circuit (including via holes) can be laminated on the lower layer conductor circuit or the upper layer conductor circuit.
Further, in the method for producing a multilayer printed wiring board according to the fourth aspect of the present invention, before forming the electroless plating film, the pretreatment liquid for electroless plating having the above composition is used on the wall surface of the opening for the via hole. Since the pretreatment is performed, it is possible to form an upper layer conductor circuit having excellent adhesion with the interlayer resin insulation layer.
[0206]
Thus, in the multilayer printed wiring board manufacturing methods of the first to fourth aspects of the present invention, a multilayer printed wiring board excellent in connection reliability and electrical characteristics can be manufactured.
Here, the manufacturing method of the multilayer printed wiring board according to the first and second aspects of the present invention is characterized by the step of forming the lower layer conductor circuit on the substrate, and the third and fourth multilayer printed wiring boards The manufacturing method is characterized by a step of forming an upper conductor circuit on the interlayer resin insulation layer. Therefore, by combining any one of the first and second multilayer printed wiring board manufacturing methods of the present invention and any one of the third and fourth multilayer printed wiring board manufacturing methods, the connection reliability can be further improved. In addition, a multilayer printed wiring board having excellent electrical characteristics can be produced.
[0207]
【Example】
Hereinafter, the present invention will be described in more detail.
Example 1
A. Preparation of resin filler
100 parts by weight of bisphenol F type epoxy monomer (manufactured by Yuka Shell Co., Ltd., molecular weight: 310, YL983U), SiO having an average particle diameter of 1.6 μm and a maximum particle diameter of 15 μm or less coated with a silane coupling agent on the surface₂ 170 parts by weight of spherical particles (manufactured by Adtech, CRS 1101-CE) and 1.5 parts by weight of a leveling agent (Perenol S4, manufactured by San Nopco) are placed in a container and mixed by stirring. A 49 Pa · s resin filler was prepared. As the curing agent, 6.5 parts by weight of an imidazole curing agent (manufactured by Shikoku Kasei Co., Ltd., 2E4MZ-CN) was used.
[0208]
B. Manufacture of multilayer printed wiring boards
(1) A copper-clad laminate 30A in which an 18 μm copper foil 32 is laminated on both surfaces of an insulating substrate 30 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 0.8 mm was used as a starting material ( FIG. 1 (a)). First, the copper-clad laminate 30A was drilled, subjected to electroless plating, and etched into a pattern, thereby forming lower conductor circuits 34 and through holes 36 on both surfaces of the substrate 30 (FIG. 1 (b)). )reference).
[0209]
(2) The substrate on which the through hole 36 and the lower conductor circuit 34 are formed is washed with water and dried, followed by NaOH (10 g / l), NaClO₂ (40 g / l), Na_Three PO_Four Blackening treatment using an aqueous solution containing (6 g / l) as a blackening bath (oxidation bath), and NaOH (10 g / l), NaBH_Four A reduction treatment using an aqueous solution containing (6 g / l) as a reducing bath was performed, and a roughened surface 38 was formed on the entire surface of the lower conductor circuit 34 including the through holes 36 (see FIG. 1C).
[0210]
(3) After preparing the resin filler described in A above, within 24 hours after preparation by the following method, the lower conductor circuit non-forming portion and the lower conductor circuit 34 in the through hole 36 and on one side of the substrate 30 are provided. A layer of the resin filler 40 was formed on the outer edge of each.
That is, first, a resin filler was pushed into a through hole using a squeegee, and then dried under conditions of 100 ° C. and 20 minutes. Next, a mask having an opening corresponding to the lower conductor circuit non-forming portion is placed on the substrate, and a layer of the resin filler 40 is formed on the lower conductor circuit non-forming portion which is a recess using a squeegee. And 100 ° C. for 20 minutes (see FIG. 1D).
[0211]
(4) One side of the substrate after the processing of (3) is subjected to belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku), and the surface of the lower conductor circuit 34 and the land 36a of the through hole 36 Polishing was performed so that the resin filler 40 did not remain on the surface, and then buffing was performed to remove scratches due to the belt sander polishing.
Such a series of polishing was similarly performed on the other surface of the substrate.
Next, heat treatment was performed at 100 ° C. for 1 hour and 150 ° C. for 1 hour to cure the resin filler 40.
[0212]
In this way, the surface layer portion of the resin filler 40 and the surface of the lower conductor circuit 34 formed in the through hole 36 and the lower conductor circuit non-forming portion are flattened, and the resin filler 40 and the side surface of the lower conductor circuit 34 are formed. A substrate in which the inner wall surface of the through hole 36 and the resin filler 40 were firmly adhered via the roughened surface 38 was obtained (see FIG. 2A). That is, by this step, the surface of the resin filler 40 and the surface of the lower conductor circuit 34 are flush.
[0213]
(5) The substrate is washed with water, alkali degreased, soft-etched, and then sprayed onto the both surfaces of the substrate by spraying to etch the surface of the lower conductor circuit 34 and the land surface 36a of the through hole 36. As a result, a roughened surface 42 was formed on the entire surface of the lower conductor circuit 34 (see FIG. 2B).
As an etchant, an etchant (MEC Etch Bond, manufactured by MEC Co.) consisting of 10 parts by weight of imidazole copper (II) complex, 7 parts by weight of glycolic acid, and 5 parts by weight of potassium chloride was used.
[0214]
(6) A copper foil with resin (MCF-6000E manufactured by Hitachi Chemical Co., Ltd., the thickness of the resin 20 is 60 μm, the thickness of the copper foil 22 is 12 μm) 20A is placed on both sides of the substrate, and then vacuum-pressed. (See FIG. 2 (c)).
Here, the vacuum press was performed under the conditions of 175 ° C., 90 min, pressure of 3 MPa, and degree of vacuum <6.5 kPa.
[0215]
(7) Next, the copper foil 22 on the surface of the crimped resin-coated copper foil 20A was etched using the etching solution (SE-07, manufactured by Mitsubishi Gas Chemical Co., Ltd.) until the thickness became 3 μm (see FIG. 2 (d)).
[0216]
(8) Next, a dry film resist (NIT-215 manufactured by Niigata Morton Co., Ltd.) is pasted on the copper foil 22, and a mask is placed on the copper foil 22, and 100 mJ / cm.² Then, development was performed with 0.8% sodium carbonate to form an etching resist 43 having an opening 43a in a via hole opening forming portion (see FIG. 3A).
[0217]
(9) Next, the copper foil 22 under the opening 43a is removed with an etching solution made of a cupric chloride solution (see FIG. 3B), and then the etching resist 43 is stripped with an aqueous sodium hydroxide solution, A copper foil 22 having an opening 22a and serving as a conformal mask was formed (see FIG. 3C).
[0218]
(10) Next, using a carbon dioxide laser irradiation device (605GTX manufactured by Mitsubishi Electric Corporation), a short pulse laser is irradiated for each opening 22a of the copper foil, and the resin 20 of the resin-coated copper foil 20A has a diameter of 60 μm. And a via hole opening 20a was provided (see FIG. 3D). Thereafter, desmear treatment was performed using oxygen plasma.
[0219]
(9) Next, by applying a palladium catalyst to the surface of the substrate on which the via hole opening 20a is formed, catalyst nuclei are attached to the surface of the copper foil 22 and the inner wall surface of the via hole opening 20a (see FIG. Not shown). That is, the substrate is made of palladium chloride (PbCl₂ ) And stannous chloride (SnCl)₂ The catalyst was imparted by immersing it in a catalyst solution containing) and depositing palladium metal.
[0220]
(10) Next, pretreatment was performed by immersing the substrate in a pretreatment solution for electroless plating having the following composition.
[Pretreatment solution for electroless plating]
NaOH 0.10 mol / l
HCHO 0.10 mol / l
[Pretreatment conditions]
3 minutes at a liquid temperature of 30 ° C
[0221]
(11) Next, the pretreated substrate is immersed in an electroless copper plating aqueous solution having the following composition, and the entire surface of the substrate including the inner wall surface of the via hole opening 20a has a thickness of 0.6 to 3 An electroless copper plating film 52 having a thickness of 0.0 μm was formed (see FIG. 4A).
[Electroless plating aqueous solution]
NiSO_Four                   0.003 mol / l
Tartaric acid 0.200 mol / l
Copper sulfate 0.030 mol / l
HCHO 0.050 mol / l
NaOH 0.100 mol / l
α, α'-bipyridyl 100 mg / l
Polyethylene glycol (PEG) 0.10 g / l
[Electroless plating conditions]
40 minutes at 34 ° C liquid temperature
[0222]
(12) A dry film resist (NIT-215 made by Nihon Morton Co., Ltd.) is pasted on the substrate on which the electroless copper plating film 52 is formed, and a mask (not shown) having a pattern formed thereon is placed at a predetermined position. , 100mJ / cm² And exposed. Thereafter, development processing was performed with 0.8% sodium carbonate to provide a plating resist 54 having an opening 54a in the via hole forming portion and the upper conductor circuit forming portion (see FIG. 4B).
[0223]
(13) Next, the substrate is washed with water at 50 ° C., degreased, washed with water at 25 ° C. and further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions to form a plating resist non-forming portion 54a. Then, an electrolytic copper plating film 56 having a thickness of 20 μm was formed (see FIG. 4C).
[Electrolytic plating solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Manufactured by Atotech Japan, Kaparaside GL)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0224]
(14) Further, after removing the plating resist 54 with 5% KOH, the electroless plating film 52 and the copper foil 22 under the plating resist 54 are dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide. Thus, an independent upper layer conductor circuit 58 (including the via hole 60) having a thickness of 18 μm was formed (see FIG. 4D).
[0225]
(15) Next, the same process as in (5) above was performed to form a roughened surface 62 on the surface of the upper layer conductor circuit 58 (including the via hole 60) (see FIG. 5A).
(16) By repeating the steps (6) to (15), the upper conductor circuit 88 (including the via hole 90) and the interlayer resin insulating layer 120 are further formed to obtain a multilayer wiring board (FIG. 5). (See (b)).
[0226]
(17) Next, the photosensitizing property obtained by acrylated 50% of an epoxy group of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) to a concentration of 60% by weight. 46.67 parts by weight of oligomer (molecular weight: 4000), 80% by weight of bisphenol A type epoxy resin (trade name: Epicoat 1001 manufactured by Yuka Shell Co., Ltd.) dissolved in methyl ethyl ketone, 15.0 parts by weight, imidazole curing agent (Shikoku Kasei Co., Ltd., trade name: 2E4MZ-CN) 1.6 parts by weight, photofunctional monomer bifunctional acrylic monomer (Nippon Kayaku Co., Ltd., trade name: R604) 4.5 parts by weight, also polyvalent acrylic monomer ( Kyoei Chemical Co., Ltd., trade name: DPE6A) 1.5 parts by weight, dispersion antifoaming agent (San Nopco, S-65) Take 1 part by weight in a container, stir and mix to prepare a mixed composition. 2.0 parts by weight of benzophenone (manufactured by Kanto Chemical Co., Inc.) as a photopolymerization initiator for this mixed composition, as a photosensitizer By adding 0.2 part by weight of Michler's ketone (manufactured by Kanto Chemical Co., Inc.), a solder resist composition having a viscosity adjusted to 2.0 Pa · s at 25 ° C. was obtained.
Viscosity measurement was performed using a B-type viscometer (DVL-B type, manufactured by Tokyo Keiki Co., Ltd.). In the case of 4 or 6 rpm, the rotor No. 3 according.
[0227]
(18) Next, the solder resist composition is applied to both surfaces of the multilayer wiring board at a thickness of 20 μm, and after drying at 70 ° C. for 20 minutes and 70 ° C. for 30 minutes, the solder resist is applied. A photomask with a thickness of 5 mm on which the pattern of the opening is drawn is brought into close contact with the solder resist layer and 1000 mJ / cm² Were exposed to UV light and developed with DMTG solution to form an opening having a diameter of 200 μm.
Further, the solder resist layer is cured by heating at 80 ° C. for 1 hour, 100 ° C. for 1 hour, 120 ° C. for 1 hour, and 150 ° C. for 3 hours. A solder resist pattern layer having a thickness of 20 μm was formed. A commercially available solder resist composition can also be used as the solder resist composition.
[0228]
(19) Next, the substrate on which the solder resist layer 93 is formed is made of nickel chloride (2.3 × 10^-1mol / l), sodium hypophosphite (2.8 × 10^-1mol / l), sodium citrate (1.6 × 10^-1The nickel plating layer 95 having a thickness of 5 μm was formed in the opening by immersing in an electroless nickel plating solution having a pH of 4.5 and a mol = l). Further, the substrate was made of potassium gold cyanide (7.6 × 10 6^-3mol / l), ammonium chloride (1.9 × 10^-1mol / l), sodium citrate (1.2 × 10^-1mol / l), sodium hypophosphite (1.7 × 10^-1The gold plating layer 96 having a thickness of 0.03 μm was formed on the nickel plating layer 95 by dipping in an electroless gold plating solution containing 1 mol / l) at 80 ° C. for 7.5 minutes.
[0229]
(20) After that, a solder paste containing tin-lead is printed on the opening of the solder resist layer on the surface on which the IC chip of the substrate is placed, and further the tin-antimony is formed on the opening of the solder resist layer 93 on the other surface. After printing the solder paste containing, solder bumps (solder bodies) 97 were formed by reflowing at 200 ° C., and a multilayer printed wiring board having the solder bumps 97 was manufactured (see FIG. 6).
[0230]
(Example 2)
In place of the steps (12) to (14) in Example 1, a multilayer printed wiring board was produced in the same manner as in Example 1 except that the following steps (1) to (3) were performed to produce a multilayer printed wiring board. A wiring board was manufactured.
[0231]
(1) The substrate on which the electroless plating film 52 was formed (see FIG. 7A) was subjected to electrolytic plating under the following conditions to form an electrolytic copper plating film 56 having a thickness of 20 μm (FIG. 7B). reference).
[Electrolytic plating solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Manufactured by Atotech Japan, Kaparaside GL)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0232]
(2) Next, a dry film resist (NIT-215 manufactured by Nichigo Morton Co., Ltd.) is pasted on the substrate on which the electrolytic copper plating film 56 is formed, and a mask (not shown) having a pattern formed thereon is placed at a predetermined position. 100mJ / cm² And exposed. Thereafter, development processing was performed with 0.8% sodium carbonate, and an L / S: 30 μm / 30 μm etching resist 55 covering the via hole forming portion and the upper conductor circuit forming portion was provided (see FIG. 7C).
[0233]
(3) Further, by performing pattern etching using an etching solution made of a cupric chloride solution, the electrolytic copper plating film 56, the electroless copper plating film 52 and the copper foil 22 under the portion where the etching resist 55 is not formed are removed. Thereafter, the etching resist 55 was peeled off with a 2% aqueous sodium hydroxide solution to form an independent upper layer conductor circuit 58 (including the via hole 60) having a thickness of 18 μm (see FIG. 7D).
[0234]
(Example 3)
A multilayer printed wiring board was produced in the same manner as in Example 1 except that the NaOH concentration in the pretreatment solution for electroless plating was 0.025 mol / l.
[0235]
Example 4
A multilayer printed wiring board was produced in the same manner as in Example 1 except that the concentration of HCHO in the pretreatment liquid for electroless plating was changed to 0.10 mol / l.
[0236]
(Example 5)
In electroless plating solution, NiSO_Four Instead of CoSO_Four (Concentration: A multilayer printed wiring board was produced in the same manner as in Example 1 except that 0.002 mol / l was used.
[0237]
(Example 6)
Instead of the step (1) of Example 1, the following steps (1) to (10) were carried out, except that the substrate 130 on which the lower conductor circuit 134 and the through hole 136 were formed was produced. A multilayer printed wiring board was produced in the same manner as in Example 1.
[0238]
(1) Starting from a copper clad laminate 130A in which 18 μm copper foil 132 is laminated on both sides of a substrate 130 made of glass epoxy resin or BT (bismaleimide-triazine) resin having a thickness of 0.8 mm, The copper foil 132 on the surface of the copper-clad laminate 130A was etched using an etching solution (SE-07 manufactured by Mitsubishi Gas Chemical Co., Ltd.) until the thickness became 3 μm (see FIG. 8A).
[0239]
(2) Next, on the copper foil 132, a dry film resist (NIT-215 manufactured by Niigata Morton Co., Ltd.) is pasted, and a mask is placed thereon to be 100 mJ / cm.² Then, the resist was exposed and developed with 0.8% sodium carbonate to form an etching resist 133 having an opening 133a in the through-hole forming portion for the through hole (see FIG. 8B).
[0240]
(3) Next, the copper foil 132 under the opening 133a is removed with an etching solution made of a cupric chloride solution, and then the etching resist 133 is peeled off with a sodium hydroxide aqueous solution to form a through-hole forming portion for a through hole. A copper foil 132 having an opening 132a and serving as a conformal mask was formed (see FIG. 8C).
[0241]
(4) Next, using a carbon dioxide laser irradiation device (605GTX manufactured by Mitsubishi Electric Corporation), a short-pulse laser of 5 shots was irradiated for each opening 132a of the copper foil to form an opening 130a in the substrate 130 (FIG. 8). (See (d)). Thereafter, desmear treatment was performed using oxygen plasma.
[0242]
(5) Next, a catalyst catalyst was attached to the surface of the copper foil 132 and the inner wall surface of the through-hole through-hole by applying a palladium catalyst to the surface of the substrate on which the through-hole through-hole 135 was formed ( Not shown). That is, the substrate 130A on which the through hole for the through hole is formed is made of palladium chloride (PdCl₂ ) And stannous chloride (SnCl)₂ The catalyst was imparted by immersing it in a catalyst solution containing) and depositing palladium metal.
[0243]
(6) Next, pretreatment was performed by immersing the substrate in a pretreatment solution for electroless plating having the following composition.
[Pretreatment solution for electroless plating]
NaOH 0.10 mol / l
HCHO 0.10 mol / l
[Pretreatment conditions]
3 minutes at a liquid temperature of 30 ° C
[0244]
(7) Next, the pretreated substrate is immersed in an electroless copper plating aqueous solution having the following composition, and a thickness of 0.6 to the entire substrate surface including the inner wall surface of the through hole 135 for through hole An electroless copper plating film 142 of 3.0 μm was formed (see FIG. 9A). [Electroless plating aqueous solution]
NiSO_Four           0.003 mol / l
Tartaric acid 0.200 mol / l
Copper sulfate 0.030 mol / l
HCHO 0.050 mol / l
NaOH 0.100 mol / l
α, α'-bipyridyl 100 mg / l
PEG 0.10 g / l
[Electroless plating conditions]
40 minutes at 34 ° C liquid temperature
[0245]
(8) A dry film resist (manufactured by NIT-215, manufactured by Nihon Morton Co., Ltd.) is attached to the substrate on which the electroless copper plating film 142 is formed, and a mask (not shown) having a pattern formed thereon is placed at a predetermined position 100mJ / cm² And exposed. Thereafter, development processing was performed with 0.8% sodium carbonate to form a plating resist 144 having openings in the through-hole forming portion and the lower conductor circuit forming portion.
[0246]
(9) Further, the substrate is washed with water at 50 ° C. and degreased, washed with water at 25 ° C. and further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions. An electrolytic copper plating film 146 having a thickness of 20 μm was formed (see FIG. 9B).
[Electrolytic plating solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Manufactured by Atotech Japan, Kaparaside GL)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0247]
(10) Next, after removing the plating resist 144 with 5% KOH, the electroless plating film 142 and the copper foil 132 under the plating resist 144 are dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide. Then, the substrate 130 on which the independent lower conductor circuit 134 and the through hole 136 were formed was produced (see FIG. 9C).
[0248]
(Example 7)
Instead of the step (1) of Example 1, the following steps (1) to (4) were performed, except that the substrate 130 on which the lower conductor circuit 134 and the through hole 136 were formed was produced. A multilayer printed wiring board was produced in the same manner as in Example 1.
[0249]
(1) First, the electroless copper plating film 142 having a thickness of 0.6 to 3.0 μm is formed on the entire surface including the inner wall surface of the through-hole 135 for through holes in the same manner as in (1) to (7) of Example 6. The board | substrate with which was formed was manufactured (refer Fig.10 (a)).
[0250]
(2) The substrate on which the electroless copper plating film 142 was formed was subjected to electrolytic plating under the following conditions to form an electrolytic copper plating film 147 having a thickness of 20 μm (see FIG. 10B). [Electrolytic plating solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Capaside GL manufactured by Atotech Japan)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0251]
(3) Next, a dry film resist (manufactured by NIT-215, manufactured by Nihon Morton Co., Ltd.) is attached to the substrate on which the electrolytic copper plating film 147 is formed, and a mask (not shown) having a pattern formed at a predetermined position 100mJ / cm² And exposed. Thereafter, development processing was performed with 0.8% sodium carbonate to form an etching resist 149 that covers the through-hole forming portion and the lower conductor circuit forming portion (see FIG. 10C).
[0252]
(4) Further, pattern etching is performed using an etching solution made of a cupric chloride solution, and then the etching resist 149 is peeled off with a 2% aqueous sodium hydroxide solution so that the independent lower layer conductor circuit 134 and the through hole 136 are separated. The formed substrate 130 was manufactured (see FIG. 10D).
[0253]
(Example 8)
A. Production of resin film for interlayer resin insulation layer
30 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 469, Epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd.), 40 parts by weight of cresol novolac type epoxy resin (epoxy equivalent 215, Epiklon N-673 manufactured by Dainippon Ink & Chemicals, Inc.), triazine 30 parts by weight of a structure-containing phenol novolak resin (phenolic hydroxyl group equivalent 120, Phenolite KA-7052 manufactured by Dainippon Ink & Chemicals, Inc.) was dissolved in 20 parts by weight of ethyl diglycol acetate and 20 parts by weight of solvent naphtha with stirring. Thereto, terminal epoxidized polybutadiene rubber (Nagase Kasei Kogyo Denarex R-45EPT) 15 parts by weight, 2-phenyl-4,5-bis (hydroxymethyl) imidazole pulverized product 1.5 parts by weight, finely pulverized silica 2 parts by weight , Silicon Added to prepare an epoxy resin composition agent 0.5 parts by weight.
The obtained epoxy resin composition was applied on a PET film having a thickness of 38 μm using a roll coater so that the thickness after drying was 50 μm, and then dried at 80 to 120 ° C. for 10 minutes, whereby an interlayer resin was obtained. A resin film for an insulating layer was produced.
[0254]
B. Preparation of resin filler
In the same manner as in Example 1, a resin filler was prepared.
[0255]
C. Manufacture of multilayer printed wiring boards
(1) A copper-clad laminate 30A in which an 18 μm copper foil 32 is laminated on both surfaces of an insulating substrate 30 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 0.8 mm was used as a starting material ( (See FIG. 11 (a)). First, the copper-clad laminate 30A was drilled, subjected to electroless plating, and etched into a pattern, thereby forming lower conductor circuits 34 and through holes 36 on both sides of the substrate (FIG. 11B). reference).
[0256]
(2) The substrate on which the lower conductor circuit 34 and the through hole 36 are formed is washed with water and dried, followed by NaOH (10 g / l), NaClO₂ (40 g / l), Na_Three PO_Four Blackening treatment using an aqueous solution containing (6 g / l) as a blackening bath (oxidation bath), and NaOH (10 g / l), NaBH_Four A reduction treatment using an aqueous solution containing (6 g / l) as a reduction bath was performed, and a roughened surface 38 was formed on the entire surface of the lower conductor circuit 34 including the through holes 36 (see FIG. 11C).
[0257]
(3) After preparing the resin filler described in B above, within 24 hours after preparation by the following method, the lower conductor circuit non-forming portion and the lower conductor circuit 34 in the through hole 36 and on one side of the substrate 1 are formed. A layer of the resin filler 40 was formed on the outer edge of each.
That is, first, a resin filler was pushed into a through hole using a squeegee, and then dried under conditions of 100 ° C. and 20 minutes. Next, a mask having an opening corresponding to the lower conductor circuit non-forming portion is placed on the substrate, and a layer of the resin filler 40 is formed on the lower conductor circuit non-forming portion which is a recess using a squeegee. And 100 ° C. for 20 minutes (see FIG. 11D).
[0258]
(4) The surface of the inner layer copper pattern 34 or the land surface of the through-hole 36 is polished on one side of the substrate after the processing of (3) by belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku) Polishing was performed so that the resin filler 40 did not remain, and then buffing was performed to remove scratches due to the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate.
Next, heat treatment was performed at 100 ° C. for 1 hour and 150 ° C. for 1 hour to cure the resin filler 40.
[0259]
In this way, the surface layer portion of the resin filler 40 and the surface of the lower conductor circuit 34 formed in the through hole 36 and the lower conductor circuit non-forming portion are flattened, and the resin filler 40 and the side surface of the lower conductor circuit 34 are formed. A substrate in which the inner wall surface of the through hole 36 and the resin filler 40 were firmly adhered via the roughened surface 38 was obtained (see FIG. 12A). That is, by this step, the surface of the resin filler 40 and the surface of the lower conductor circuit 34 are flush.
[0260]
(5) After washing the substrate with water and acid degreasing, soft etching is performed, and then an etching solution is sprayed on both surfaces of the substrate to spray the surface of the lower conductor circuit 34, the land surface 36a of the through hole 36, and the inner wall. By etching, a roughened surface 42 was formed on the entire surface of the lower conductor circuit 34 (see FIG. 12B).
As an etchant, an etchant (MEC Etch Bond, manufactured by MEC Co.) consisting of 10 parts by weight of imidazole copper (II) complex, 7 parts by weight of glycolic acid, and 5 parts by weight of potassium chloride was used.
[0261]
(6) Next, on both sides of the substrate, an interlayer resin insulation layer resin film slightly larger than the substrate prepared in A is placed on the substrate, and the pressure is 4 kgf / cm.² Then, after temporarily crimping and cutting under conditions of a temperature of 80 ° C. and a crimping time of 10 seconds, an interlayer resin insulation layer 20 was formed by further bonding using a vacuum laminator apparatus by the following method (FIG. 12C). reference). That is, a resin film for an interlayer resin insulation layer is placed on a substrate with a vacuum degree of 0.5 Torr and a pressure of 4 kgf / cm.² The film was subjected to main pressure bonding under conditions of a temperature of 80 ° C. and a pressure bonding time of 60 seconds, and then thermally cured at 170 ° C. for 30 minutes.
[0262]
(7) Next, the substrate on which the interlayer resin insulation layer 20 is formed is immersed in an 80 ° C. solution containing 60 g / l of permanganic acid for 10 minutes, and the epoxy resin particles present on the surface of the interlayer resin insulation layer 20 are removed. By dissolving and removing, the surface of the interlayer resin insulation layer 20 was made rough. The formed rough surface is not shown.
[0263]
(8) Next, using a SV-4540 manufactured by Nippon Vacuum Engineering Co., sputtering using Cu as a target was performed under conditions of a gas pressure of 0.5 Pa, a temperature of 120 ° C., a power of 600 W, and a time of 30 minutes, and a Cu metal layer 12 was formed on the surface of the interlayer resin insulation layer 20 (see FIG. 12D). The formed Cu metal layer has a thickness of 0.5 μm.
[0264]
(9) Next, on the Cu metal layer, a dry film resist (NIT-215 manufactured by Nihon Morton Co., Ltd.) is pasted and a mask is placed, and 100 mJ / cm.² Then, the resist was exposed and developed with 0.8% sodium carbonate to form an etching resist 43 having an opening 43a in the via hole opening forming portion (see FIG. 13A).
[0265]
(10) Next, the Cu metal layer under the opening 43a is removed with an etching solution made of a cupric chloride solution (see FIG. 13B), and then the etchant resist 43 is stripped with an aqueous sodium hydroxide solution. A Cu metal layer 12 having an opening 12a and serving as a conformal mask was formed (see FIG. 13C).
[0266]
(11) Next, using a carbon dioxide laser irradiation device (605GTX manufactured by Mitsubishi Electric Corporation), each shot 12a of the Cu metal layer is irradiated with a 5-shot short pulse laser, and an opening having a diameter of 60 μm is formed in the interlayer resin insulation layer. It formed (refer FIG.13 (d)). Thereafter, desmear treatment was performed using oxygen plasma.
[0267]
(12) Next, by applying a palladium catalyst to the surface of the substrate on which the via hole opening was formed, catalyst nuclei were attached to the surface of the Cu metal layer 12 and the inner wall surface of the via hole opening 20a (see FIG. Not shown). That is, the substrate is made of palladium chloride (PbCl₂ ) And stannous chloride (SnCl)₂ The catalyst was imparted by immersing it in a catalyst solution containing) and depositing palladium metal.
[0268]
(13) Next, pretreatment was performed by immersing the substrate in a pretreatment solution for electroless plating having the following composition.
[Pretreatment solution for electroless plating]
NaOH 0.10 mol / l
HCHO 0.10 mol / l
[Pretreatment conditions]
3 minutes at 30 ℃ liquid temperature
[0269]
(14) Next, the pretreated substrate is immersed in an electroless copper plating aqueous solution having the following composition, and the entire surface of the substrate including the inner wall surface of the via hole opening has a thickness of 0.6 to 3. An electroless copper plating film 52 having a thickness of 0 μm was formed (see FIG. 14A).
[Electroless plating aqueous solution]
NiSO_Four                   0.003 mol / l
Tartaric acid 0.200 mol / l
Copper sulfate 0.030 mol / l
HCHO 0.050 mol / l
NaOH 0.100 mol / l
α, α'-bipyridyl 100 mg / l
Polyethylene glycol (PEG) 0.10 g / l
[Electroless plating conditions]
40 minutes at 34 ° C liquid temperature
[0270]
(15) A dry film resist (NIT-215 manufactured by Nichigo Morton Co., Ltd.) is attached to the substrate on which the electroless copper plating film 52 is formed, and a mask (not shown) having a pattern formed thereon is placed at a predetermined position. , 100mJ / cm² And exposed. Thereafter, development processing was performed with 0.8% sodium carbonate to provide a plating resist 54 having an opening 54a in the via hole forming portion and the conductor circuit forming portion (see FIG. 14B).
[0271]
(16) Next, the substrate is washed with 50 ° C. water and degreased, washed with 25 ° C. water and further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions to form a plating resist non-forming portion 54a. Then, an electrolytic copper plating film 56 having a thickness of 20 μm was formed (see FIG. 14C).
[Electrolytic plating solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Manufactured by Atotech Japan, Kaparaside GL)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0272]
(17) Further, after removing the plating resist 54 with 5% KOH, the electroless plating film 52 and the Cu metal layer 12 under the plating resist 54 are dissolved by etching with a mixed solution of sulfuric acid and hydrogen peroxide. This was removed to form an independent upper layer conductor circuit 58 (including the via hole 60) (see FIG. 14D).
[0273]
(18) Next, the same process as in (5) was performed, and a roughened surface 62 was formed on the surface of the upper layer conductor circuit 58 (including the via hole 60) (see FIG. 15A).
(19) By repeating the steps (6) to (18), the upper conductor circuit 88 (including the via hole 90) and the interlayer resin insulating layer 120 are further formed to obtain a multilayer wiring board (FIG. 15 ( b)).
[0274]
(20) Furthermore, a solder resist layer and solder bumps were formed in the same manner as in the steps (17) to (20) of Example 1 to obtain a multilayer printed wiring board (see FIG. 16).
[0275]
(Comparative Example 1)
A multilayer printed wiring board was produced in the same manner as in Example 1 except that a pretreatment liquid for electroless plating having the following composition was used as the pretreatment liquid for electroless plating.
[Pretreatment solution for electroless plating]
NaOH 0.005 mol / l
HCHO 0.10 mol / l
[0276]
(Comparative Example 2)
A multilayer printed wiring board was produced in the same manner as in Example 1 except that a pretreatment liquid for electroless plating having the following composition was used as the pretreatment liquid for electroless plating.
[Pretreatment solution for electroless plating]
NaOH 0.30 mol / l
HCHO 0.10 mol / l
[0277]
(Comparative Example 3)
A multilayer printed wiring board was produced in the same manner as in Example 1 except that a pretreatment liquid for electroless plating having the following composition was used as the pretreatment liquid for electroless plating.
[Pretreatment solution for electroless plating]
NaOH 0.10 mol / l
HCHO 0.05 mol / l
[0278]
In the multilayer printed wiring boards obtained in Examples 1 to 8 and Comparative Examples 1 to 3, the shape of the electroless plating film and the peel strength of the electroless plating film were evaluated. The results are shown in Table 1. In addition, the shape of the electroless plating film was evaluated by the following evaluation method.
Moreover, about the said multilayer printed wiring board, the continuity test was done and the presence or absence of a disconnection was evaluated. The results are shown in Table 1.
[0279]
(1) Shape of electroless plating film
The multilayer printed wiring board was cut longitudinally so as to include a via hole, the shape of the electroless plating film was observed with a microscope, and evaluated according to the following evaluation criteria.
Evaluation criteria
○. There is no undeposited portion of the electroless plating film, and the thickness is uniform.
×. There is an undeposited portion of the electroless plating film, or the thickness varies.
[0280]
[Table 1]

[0281]
As shown in Table 1, in the multilayer printed wiring boards (Examples 1 to 8) obtained by using the method for producing a multilayer printed wiring board according to the present invention, the thickness of the interlayer resin insulation layer and the entire surface of the substrate was increased. The peel strength of this electroless plating film is sufficiently high at 0.90 kg / cm or more, and the obtained multilayer printed wiring board has good connectivity. It was.
On the other hand, in the multilayer printed wiring boards of Comparative Examples 1 to 3, the electroless plating film having a uniform thickness is not formed on the entire surface of the interlayer resin insulation layer, Uneven portions were seen. In addition, the peel strength of the electroless plating film is 0.70 kg / cm or less and the adhesion of the electroless plating film is not sufficient, and the obtained multilayer printed wiring board has some poor connection, The connectivity was low compared to the example.
[0282]
【The invention's effect】
As described above, the multilayer printed wiring board manufacturing method according to the first to fourth aspects of the present invention has the above-described configuration, so that the adhesion between the substrate and the interlayer resin insulation layer and the conductor circuit is excellent and reliable. A multilayer printed wiring board having excellent electrical characteristics can be produced.
[Brief description of the drawings]
FIGS. 1A to 1D are cross-sectional views showing a part of steps of a method for producing a multilayer printed wiring board according to the present invention.
FIGS. 2A to 2D are cross-sectional views illustrating a part of the process of the method for producing a multilayer printed wiring board according to the present invention.
FIGS. 3A to 3D are cross-sectional views showing a part of the steps of the method for producing a multilayer printed wiring board according to the present invention. FIGS.
FIGS. 4A to 4D are cross-sectional views showing a part of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention. FIGS.
FIGS. 5A and 5B are cross-sectional views illustrating a part of the process of the method for producing a multilayer printed wiring board according to the present invention. FIGS.
FIG. 6 is a cross-sectional view showing a multilayer printed wiring board obtained by the method for producing a multilayer printed wiring board of the present invention.
7A to 7D are cross-sectional views showing a part of the steps of the method for producing a multilayer printed wiring board according to the present invention.
FIGS. 8A to 8D are cross-sectional views showing a part of the process of the method for producing a multilayer printed wiring board according to the present invention. FIGS.
FIGS. 9A to 9C are cross-sectional views illustrating a part of the steps of the method for producing a multilayer printed wiring board according to the present invention. FIGS.
FIGS. 10A to 10D are cross-sectional views illustrating a part of the process of the method for producing a multilayer printed wiring board according to the present invention.
FIGS. 11A to 11D are cross-sectional views illustrating a part of the steps of the method for producing a multilayer printed wiring board according to the present invention. FIGS.
12 (a) to 12 (d) are cross-sectional views showing a part of the steps of the method for producing a multilayer printed wiring board according to the present invention.
FIGS. 13A to 13D are cross-sectional views illustrating a part of the process of the method for producing a multilayer printed wiring board according to the present invention. FIGS.
FIGS. 14A to 14D are cross-sectional views illustrating a part of the process of the method for producing a multilayer printed wiring board according to the present invention.
FIGS. 15A and 15B are cross-sectional views showing a part of the steps of the method for producing a multilayer printed wiring board according to the present invention. FIGS.
FIG. 16 is a cross-sectional view showing a multilayer printed wiring board obtained by the method for producing a multilayer printed wiring board of the present invention.
FIGS. 17A to 17G are cross-sectional views showing a part of a manufacturing process of a multilayer printed wiring board using a conventional conformal mask. FIGS.
[Explanation of symbols]
20, 120 Interlayer resin insulation layer
30, 130 Insulating substrate
32 Copper foil
34, 134 Lower layer conductor circuit
36 Through hole
38 Roughened surface
40 Resin filler
43 Etching resist
52 Electroless copper plating film
54 Plating resist
56 Electrolytic copper plating film
58, 88 Upper layer conductor circuit
60, 90 Viahole
93 Solder resist layer
95 Nickel plating film
96 Gold plating film
97 Solder bump

Claims (2)

On a substrate on which a lower layer conductor circuit is formed, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated, and a method for producing a multilayer printed wiring board in which these conductor circuits are connected via via holes,
The step of forming the upper layer conductor circuit is a step of forming a resin / metal layer composed of a resin layer and a metal layer on at least (A) the lower layer conductor circuit or the upper layer conductor circuit,
(B) A step of sequentially performing an opening formation process on the resin layer and the metal layer constituting the resin / metal layer, forming an opening for a via hole by the opening formation process , and further applying a Pd catalyst ;
(C) A pretreatment liquid for electroless plating comprising an aqueous solution containing 0.025 to 0.1 mol / l alkaline compound and 0.1 to 0.3 mol / l reducing agent on the resin / metal layer. The step of applying the pretreatment used,
(D) forming an electroless plating film on the surface of the pretreated resin / metal layer;
(E) forming a plating resist on a part of the electroless plating film;
(F) forming an electrolytic plating film on the plating resist non-forming portion; and
After separating the (G) said plating resist comprises, as the engineering to remove the electroless plated film and the metal layer under the plating resist,
In the step (B), the diameter of the via hole opening is 80 μm or less,
In the step (C), the pretreatment temperature is 20 to 50 ° C., and the pretreatment time is 0.5 to 5 minutes,
The electroless plating solution used in the step (D) is composed of an aqueous solution containing an alkaline compound, a reducing agent, copper ions, and tartaric acid or a salt thereof, and further selected from the group consisting of nickel ions, cobalt ions, and iron ions. At least one metal ion
The concentration of the alkaline compound is 0.025 to 0.25 mol / l,
The concentration of the reducing agent is 0.03 to 0.15 mol / l,
The concentration of the copper ions is 0.02 to 0.06 mol / l,
The concentration of the tartaric acid or salt thereof is 0.05 to 0.3 mol / l.
A method for producing a multilayer printed wiring board, comprising: On a substrate on which a lower layer conductor circuit is formed, an interlayer resin insulating layer and an upper layer conductor circuit are sequentially laminated, and a method for producing a multilayer printed wiring board in which these conductor circuits are connected via via holes,
The step of forming the upper layer conductor circuit is a step of forming a resin / metal layer composed of a resin layer and a metal layer on at least (A) the lower layer conductor circuit or the upper layer conductor circuit,
(B) A step of sequentially performing an opening formation process on the resin layer and the metal layer constituting the resin / metal layer, forming an opening for a via hole by the opening formation process , and further applying a Pd catalyst ;
(C) A pretreatment liquid for electroless plating comprising an aqueous solution containing 0.025 to 0.1 mol / l alkaline compound and 0.1 to 0.3 mol / l reducing agent on the resin / metal layer. The step of applying the pretreatment used,
(D) forming an electroless plating film on the surface of the pretreated resin / metal layer;
(E) forming an electroplating film on the electroless plating film;
(F) forming an etching resist on a portion of the electrolytic plating film; and
(G) comprises said etching resist non-electrolytic plating film forming men and electroless plated film and the metal layer as engineering is removed by etching,
In the step (B), the diameter of the via hole opening is 80 μm or less,
In the step (C), the pretreatment temperature is 20 to 50 ° C., and the pretreatment time is 0.5 to 5 minutes,
The electroless plating solution used in the step (D) is composed of an aqueous solution containing an alkaline compound, a reducing agent, copper ions, and tartaric acid or a salt thereof, and further selected from the group consisting of nickel ions, cobalt ions, and iron ions. At least one metal ion
The concentration of the alkaline compound is 0.025 to 0.25 mol / l,
The concentration of the reducing agent is 0.03 to 0.15 mol / l,
The concentration of the copper ions is 0.02 to 0.06 mol / l,
The concentration of the tartaric acid or salt thereof is 0.05 to 0.3 mol / l.
A method for producing a multilayer printed wiring board, comprising:

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