JP4153704B2 - Laminate and printed wiring board manufacturing method - Google Patents

Description

【００３９】
該溶液に使用される溶媒は、上記化合物を溶解するものであれば良い。例示すると、水、トルエン、キシレン、テトラヒドロフラン、２−プロパノール、１−ブタノール、酢酸エチル、Ｎ，Ｎ−ジメチルフォルムアミド、アセチルアセトンなどが使用可能である。これらの溶剤を２種類以上混合して使用しても良く、ポリアミド酸のケミカルキュア剤成分を混合することも可能である。本発明において、Ｎ，Ｎ−ジメチルフォルムアミド、１−ブタノール、２−プロパノールおよび水が特に好ましく用いられ得る。
【００４０】
溶液の濃度は、好ましくは０．０１％〜１０％、さらに好ましくは０．１％〜５％が好適である。即ち溶液中の前記元素の濃度は１ｐｐｍから１００，０００ｐｐｍが好ましく、１０ｐｐｍ〜５０，０００ｐｐｍがより好ましい。
【００４１】
ゲルフィルムに該溶液を塗布または浸漬の後、表面の余分な液滴を除去する工程を加えることにより、フィルム表面にムラのない外観の優れたポリイミドフィルムを得ることができるので好ましい。液滴の除去は、ニップロール、エアナイフ、ドクターブレードなどの公知の方法が利用可能であり、フィルムの外観、液切り性、作業性等の観点より、ニップロールが好ましく用いられ得る。
また、ポリイミドフィルムを製造する任意の段階で各種の有機添加剤、無機のフィラー類、あるいは各種の強化材を添加し、複合化されたポリイミドフィルムとすることも可能である。
【００４２】
本発明におけるポリイミドフィルムは、厚みの制限は無いが５μｍ〜１２５μｍが好ましい。特に多層プリント配線板用途としてはポリイミドフィルムの厚みは１０〜７５μｍ、好ましくは１０〜５０μｍ、引張り弾性率は４ＧＰａ以上、好ましくは６ＧＰａ以上、より好ましくは１０ＧＰａ以上、線膨張係数は１７ｐｐｍ以下、好ましくは１２ｐｐｍ以下、より好ましくは１０ｐｐｍ以下、吸水率は２％以下、好ましくは１．５％以下、より好ましくは１%以下のものが好適である。また高分子フィルムの表面粗さがＲｚで２μｍ以下好ましくは１μｍ以下のものが高密度配線の形成に好適である。
【００４３】
高分子フィルム表面に第一金属被膜を形成する方法は、真空蒸着法、スパッタリング法、イオンプレーティング法、ＣＶＤ法などの物理的手法が好適である。これは、絶縁基板にめっき触媒を付与する必要はなく、従って第一金属被膜エッチング後にめっき触媒が残ることもないという点、湿式無電解めっきの様に密着性向上のため表面粗化処理（デスミア処理）を行う必要がなく、金属皮膜と絶縁基板の界面が平滑となり、狭間隔の回路形成や、電気特性に良い影響を与えるという点が理由として挙げられる。物理的手法としては、成膜の生産性、高分子フィルムとの密着性、等の観点からスパッタリング法が好ましい。第一金属皮膜の厚みとしては、５ｎｍから１０００ｎｍが好ましい。５ｎｍ未満の場合、絶縁基板表面を均一に積層できず、絶縁基板と金属層の充分な密着が得られない。また、１０００ｎｍを越えて形成すると、経済的でないばかりでなく、第一金属層と第二金属層との内部応力差から絶縁基板との密着力が低下する、回路部に抵抗の高いニッケルやニッケル合金の比率が大きくなり伝送特性が悪化する、不要な部分の第一金属層をエッチング除去する際に時間がかかり、第二金属被膜による回路パターンがエッチングの影響を受け回路形状が悪化する、等の問題が生じる。第一金属層形成後、接着層の形成、積層加工、その他の加工工程で第一層が劣化、汚染することを防ぐため、第一層表面に再剥離可能な保護フィルムを積層しても良い。
次いで、必要に応じてスルーホールやＩＶＨを穴開けする。これらはパンチング加工、ドリル加工、レーザー加工、感光性樹脂を用いる方法、湿式のエッチングによる方法、プラズマ等の乾式エッチングによる方法などを単独であるいはこれらの方法を組み合わせて適用できる。微細加工、生産性、等の観点からレーザー加工、特にＵＶ−ＹＡＧレーザーやエキシマレーザーが好適である。
形成したスルーホールやＩＶＨを導通するために無電解めっきによる第二金属層を形成する。無電解ニッケルめっきとしては、公知の無電解ニッケルめっきが適用できる。
この様にして得られた無電解めっき被膜の表面に電気銅めっきを施す。実質的に、この電気銅めっき層がプリント配線板の回路パターンを形成する。無電解ニッケルめっきと電気めっきの密着性を向上するために、ニッケル表面を洗浄、粗化、等を行っても良い。
【００４４】
また、高分子フィルムの一方の面に上記の金属層を形成し、他方の面に接着層を形成した積層体について、接着層に関しては、特に種類を制限されるものでなく、公知の樹脂を適用でき、大きくは（Ａ）熱可塑性樹脂を用いた熱融着性の接着剤、（Ｂ）熱硬化樹脂の硬化反応を利用した硬化型の接着剤に分けることができる。これらについて以下に説明する。
（Ａ）接着剤に熱融着性を与える熱可塑性樹脂としては、ポリイミド樹脂、ポリアミドイミド樹脂、ポリエーテルイミド樹脂、ポリアミド樹脂、ポリエステル樹脂、ポリカーボネート樹脂、ポリケトン系樹脂、ポリスルホン系樹脂、ポリフェニレンエーテル樹脂、ポリオレフィン樹脂、ポリフェニレンスルフィド樹脂、フッ素樹脂、ポリアリレート樹脂、液晶ポリマー樹脂等が挙げられ、これらの１種または２種以上を適宜組合わせて本発明の積層体の接着層として用いることができる。中でも優れた耐熱性、電気信頼性等の観点より熱可塑性ポリイミド樹脂を用いることが好ましい。
【００４５】
ここで熱可塑性ポリイミド樹脂の製造方法について説明する。ポリイミド樹脂はその前駆体であるポリアミド酸重合体溶液から得られるが、このポリアミド酸重合体溶液は、前述のごとき公知の方法で製造することができる。すなわち、テトラカルボン酸二無水物成分とジアミン成分を実質等モル使用し、有機極性溶媒中で重合して得られる。この熱可塑性ポリイミド樹脂に用いられる酸二無水物は、酸二無水物であれば特に限定されない。酸二無水物成分の例としては、ブタンテトラカルボン酸二無水物、１，２，３，４−シクロブタンテトラカルボン酸二無水物、１，３−ジメチル−１，２，３，４−シクロブタンテトラカルボン酸、１，２，３，４−シクロペンタンテトラカルボン酸二無水物、２，３，５−トリカルボキシシクロペンチル酢酸二無水物、３，５，６−トリカルボキシノルボナン−２−酢酸二無水物、２，３，４，５−テトラヒドロフランテトラカルボン酸二無水物、５−（２，５−ジオキソテトラヒドロフラル）−３−メチル−３−シクロヘキセン−１，２−ジカルボン酸二無水物、ビシクロ［２，２，２］−オクト−７−エン−２，３，５，６−テトラカルボン酸二無水物等の脂肪族または脂環式テトラカルボン酸二無水物；ピロメリット酸二無水物、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物、３，３’，４，４’−ジフェニルスルホンテトラカルボン酸二無水物、１，４，５，８−ナフタレンテトラカルボン酸二無水物、２，３，６，７−ナフタレンテトラカルボン酸二無水物、４，４’−オキシフタル酸無水物、３，３’，４，４’−ジメチルジフェニルシランテトラカルボン酸二無水物、３，３‘，４，４’−テトラフェニルシランテトラカルボン酸二無水物、１，２，３，４−フランテトラカルボン酸二無水物、４，４‘−ビス（３，４−ジカルボキシフェノキシ）ジフェニルスルフィド二無水物、４，４‘−ビス（３，４−ジカルボキシフェノキシ）ジフェニルスルホン二無水物、４，４‘−ビス（３，４−ジカルボキシフェノキシ）ジフェニルプロパン二無水物、４，４‘−ヘキサフルオロイソプロピリデンジフタル酸無水物、３，３’，４，４‘−ビフェニルテトラカルボン酸二無水物、２，３，３’，４‘−ビフェニルテトラカルボン酸二無水物、ビス（フタル酸）フェニルホスフィンオキサイド二無水物、ｐ−フェニレン−ビス（トリフェニルフタル酸）二無水物、ｍ−フェニレン−ビス（トリフェニルフタル酸）二無水物、ビス（トリフェニルフタル酸）−４，４’−ジフェニルエーテル二無水物、ビス（トリフェニルフタル酸）−４，４’−ジフェニルメタン二無水物等の芳香族テトラカルボン酸二無水物、２，２−ビス（４−ヒドロキシフェニル）プロパンジベンゾエート−３，３’，４，４’−テトラカルボン酸二無水物、ｐ−フェニレンビス（トリメリット酸モノエステル無水物）、４，４’−ビフェニレンビス（トリメリット酸モノエステル無水物）、１，４−ナフタレンビス（トリメリット酸モノエステル無水物）、１，２−エチレンビス（トリメリット酸モノエステル無水物）、１，３−トリメチレンビス（トリメリット酸モノエステル無水物）、１，４−テトラメチレンビス（トリメリット酸モノエステル無水物）、１，５−ペンタメチレンビス（トリメリット酸モノエステル無水物）、１，６−ヘキサメチレンビス（トリメリット酸モノエステル無水物）、４，４’−（４，４’−イソプロピリデンジフェノキシ）ビス（無水フタル酸）などが好ましく、これらの１種を、または２種以上を組み合わせて酸二無水物成分の一部または全部として用いることができる。
【００４６】
優れた熱融着性の発現のためには、２，２−ビス（４−ヒドロキシフェニル）プロパンジベンゾエート−３，３’，４，４’−テトラカルボン酸二無水物、１，２−エチレンビス（トリメリット酸モノエステル無水物）、４，４’−ヘキサフルオロイソプロピリデンジフタル酸無水物、２，３，３’，４‘−ビフェニルテトラカルボン酸二無水物、４，４’−オキシジフタル酸無水物、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物、４，４’−（４，４’−イソプロピリデンジフェノキシ）ビス（無水フタル酸）を用いるのが好ましい。
【００４７】
また、ジアミン成分としては４，４’−ジアミノジフェニルエーテル、３，４’−ジアミノジフェニルエーテル、２，２−ビス［４−（４−アミノフェノキシ）フェニル］プロパン、２，２，−ビス［３−（３−アミノフェノキシ）フェニル］プロパン、１，４−ビス（４−アミノフェノキシ）ベンゼン、１，３−ビス（４−アミノフェノキシ）ベンゼン、１，３−ビス（３−アミノフェノキシ）ベンゼン、ビス（４−（４−アミノフェノキシ）フェニル）スルフォン、ビス（４−（３−アミノフェノキシ）フェニル）スルフォン、４，４’−ビス（４−アミノフェノキシ）ビフェニル、２，２−ビス（４−アミノフェノキシフェニル）ヘキサフルオロプロパン、４、４’−ジアミノジフェニルスルフォン、３、３’−ジアミノジフェニルスルフォン、９、９−ビス（４−アミノフェニル）フルオレン、ビスアミノフェノキシケトン、４、４’−（１，４−フェニレンビス（１−メチルエチリデン））ビスアニリン、４、４’−（１，３−フェニレンビス（１−メチルエチリデン））ビスアニリン、３，３’−ジメチルベンジジン、３，３’−ジヒドロキシベンジジン等を挙げることができ、これらを単独で、または２種以上を組合わせて用いることができる。
【００４８】
本発明の積層体に用いる熱可塑性ポリイミド樹脂の材料としては、１，３−ビス（３−アミノフェノキシ）ベンゼン、３，３’−ジヒドロキシベンジジン、ビス（４−（３−アミノフェノキシ）フェニル）スルフォンをそれぞれ単独または任意の割合で混合して用いることが好ましい。
【００４９】
ポリアミド酸重合体溶液を得る反応の代表的な手順として、１種以上のジアミン成分を有機極性溶剤に溶解または拡散させ、その後１種以上の酸二無水物成分を添加しポリアミド酸溶液を得る方法が挙げられる。各モノマーの添加順序は特に限定されず、酸二無水物成分を有機極性溶媒に先に加えておき、ジアミン成分を添加し、ポリアミド酸重合体の溶液としても良いし、ジアミン成分を有機極性溶媒中に先に適量加えて、次に過剰の酸二無水物成分を加え、過剰量に相当するジアミン成分を加えて、ポリアミド酸重合体の溶液としても良い。この他にも、当業者に公知の様々な添加方法がある。なお、ここでいう「溶解」とは、溶媒が溶質を完全に溶解する場合の他に、溶質が溶媒中に均一に分散または拡散されて実質的に溶解しているのと同様の状態になる場合を含む。
【００５０】
ポリアミド酸溶液の生成反応に用いられる有機極性溶媒としては、例えば、ジメチルスルホキシド、ジエチルスルホキシド等のスルホキシド系溶媒、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジエチルホルムアミド等のホルムアミド系溶媒、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジエチルアセトアミド等のアセトアミド系溶媒、Ｎ−メチル−２−ピロリドン、Ｎ−ビニル−２−ピロリドン等のピロリドン系溶媒、フェノール、ｏ−、ｍ−、またはｐ−クレゾール、キシレノール、ハロゲン化フェノール、カテコールなどのフェノール系溶媒、あるいはヘキサメチルホスホルアミド、γ−ブチロラクトンなどを挙げることができる。更に必要に応じて、これらの有機極性溶媒とはキシレン、トルエンのような芳香族炭化水素とを組み合わせて用いることもできる。
【００５１】
次に、ポリアミド酸をイミド化する方法について説明する。
【００５２】
ポリアミド酸のイミド化反応はポリアミド酸の脱水閉環反応であり、反応によって水を生成する。この生成した水は、ポリアミド酸を容易に加水分解し分子量の低下を引き起こす。この水を除去しながらイミド化する方法として、通常１）トルエン・キシレン等の共沸溶媒を加え共沸により除去する方法、２）無水酢酸等の脂肪族酸二無水物とトリエチルアミン・ピリジン・ピコリン・イソキノリン等の３級アミンを加える化学的イミド化法、３）減圧下で加熱してイミド化する方法がある。
【００５３】
本発明の熱可塑性ポリイミド樹脂のイミド化の方法は、減圧下で加熱してイミド化する方法が好ましい。このイミド化の方法によれば、イミド化によって生成する水を積極的に系外に除去できるので、ポリアミド酸の加水分解を抑えることが可能で高分子量のポリイミドが得られる。またこの方法によれば、原料の酸二無水物中に不純物として存在する片側または両側開環物が再閉環するので、より一層の分子量の向上効果が期待できる。
【００５４】
減圧下で加熱イミド化する方法の加熱条件は８０〜４００℃が好ましいが、イミド化が効率よく行われ、しかも水が効率よく除かれる１００℃以上がより好ましく、更に好ましくは１２０℃以上である。最高温度は目的とするポリイミドの熱分解温度以下が好ましく、通常のイミド化の完結温度すなわち２５０〜３５０℃程度が通常適用される。
【００５５】
減圧する圧力の条件は、小さいほうが好ましいが、具体的には９００ｈＰａ以下、好ましくは８００ｈＰａ以下、より好ましくは７００ｈＰａ以下である。
また、熱可塑性ポリイミド樹脂を得るための別の方法として、上記の熱的または化学的に脱水閉環する方法において溶媒の蒸発を行わない方法もある。具体的には、熱的イミド化処理または脱水剤による化学的イミド化処理を行って得られるポリイミド樹脂溶液を貧溶媒中に投入して、ポリイミド樹脂を析出させ、未反応モノマーを取り除いて精製、乾燥させ固形のポリイミド樹脂を得る方法である。貧溶媒としては、溶媒とは良好に混合するがポリイミドは溶解しにくい性質を有するものを選択し、例示すると、アセトン、メタノール、エタノール、イソプロパノール、ベンゼン、メチルセロソルブ、メチルエチルケトン等が挙げられるがこれに限定されない。これらの方法により熱可塑性ポリイミド樹脂を得ることができ、本発明の積層体の接着層として用いることができる。
【００５６】
次に（Ｂ）熱硬化樹脂の硬化反応を利用した硬化型の接着剤に関して説明する。熱硬化型樹脂としてはビスマレイミド樹脂、ビスアリルナジイミド樹脂、フェノール樹脂、シアナート樹脂、エポキシ樹脂、アクリル樹脂、メタクリル樹脂、トリアジン樹脂、ヒドロシリル硬化樹脂、アリル硬化樹脂、不飽和ポリエステル樹脂等を挙げることができ、これらを単独または適宜組み合わせて用いることができる。また、上記熱硬化性樹脂以外に高分子鎖の側鎖または末端にエポキシ基、アリル基、ビニル基、アルコキシシリル基、ヒドロシリル基，水酸基等の反応性基を有する側鎖反応性基型熱硬化性高分子を熱硬化成分として使用することも可能である。
以下に側鎖反応性基型熱硬化性ポリイミド樹脂について説明する。具体的製法例としては、（１）既に述べた熱可塑性ポリイミド樹脂に準じた方法で製造され、この際にエポキシ基、ビニル基、アリル基、メタクリル基、アクリル基、アルコキシシリル基、ヒドロシリル基、カルボキシ基、水酸基、シアノ基等の官能基有するジアミン成分、酸二無水物成分をモノマー成分として用い熱硬化型ポリイミドを得る方法、また、（２）水酸基、カルボキシ基、芳香族ハロゲン基等を有する溶媒可溶性ポリイミドを既に述べた熱可塑性ポリイミド樹脂の製法に準じて製造した後、エポキシ基、ビニル基、アリル基、メタクリル基、アクリル基、アルコキシシリル基、ヒドロシリル基、カルボキシ基、水酸基、シアノ基等の官能基を化学反応により付与する方法等により、熱硬化性ポリイミド樹脂を得ることも可能である。
熱硬化性樹脂に対し、さらに有機過酸化物等のラジカル反応開始剤、反応促進剤、トリアリルシアヌレート、トリアリルイソシアヌレート等の架橋助剤、耐熱性、接着性等の向上のため、必要に応じて、酸二無水物系、アミン系、イミダゾール系等の一般に用いられるエポキシ硬化剤、種々のカップリング剤等を適宜添加することも可能である。
【００５７】
加熱接着時の接着剤の流れ性を制御する目的で、前記熱可塑性樹脂に熱硬化性樹脂を混合することも可能である。このためには、熱可塑性樹脂１００重量部に対して、熱硬化性樹脂を１〜１００００重量部、好ましくは５〜２０００重量部加えるのが望ましい。熱硬化性樹脂が多すぎると接着層が脆くなるおそれがあり、逆に少なすぎると接着剤のはみ出しが生じたり、接着性が低下するおそれがある。
本発明の積層体に用いる接着剤として、熱可塑性ポリイミド樹脂とエポキシ樹脂を混合したものが接着性、加工性、耐熱性などのバランスがよく好適である。
【００５８】
高分子フィルムに接着層を形成する方法は、公知の湿式コーティング法が適用できる。具体的には、グラビアコーター、ダイコーター、カーテンコーター、スピンコーター、ナイフコーター、スプレーコーターなどが例示できる。ロール状の高分子フィルムに連続的にコーティングするには、グラビアコーター、ダイコーター、カーテンコーターなどが好適である。本積層体を用いて多層プリント配線板を作製するためには接着層はたとえば、硬化反応を進めすぎず、溶剤成分を蒸発させた半硬化状態（Ｂステージ状態）とする。
上記積層体を用いてプリント配線板を製造する方法は、たとえば以下の工程を例示できる。
（１）高分子フィルムの一方の面に物理的方法で第１層を形成し、他方の面に接着層を形成する。
（２）内層基板に上記積層体を内層回路面と接着面を合わせ、プレス積層する。プレス積層加工は単板プレスの他、真空プレスも適用でき、積層時の泡の咬み込み、内層回路の埋め込み性、第一金属層の酸化を防ぐ、等の点から真空プレスが好ましい。加熱温度は１８０℃〜２００℃で１〜３時間程度である。
（３）必要な位置にビアホールを形成する。ビアホールの穴開けは、レーザードリリングが小径ビアのブラインドビア形成に有効であり、第１金属被膜ごと穴開けするためにはＵＶ−ＹＡＧレーザーが好適である。
（４）無電解ニッケルめっきにより、形成したスルーホールやＩＶＨを導通する。
（５）回路の形成を予定する部分を除く部分にレジスト被膜を形成する。本発明に用いるレジスト被膜としては、回路パターンを形成する電気めっき液に耐え、このめっきを行ったときに、その表面に第二金属皮膜が形成されにくいものであれば特に限定するものではなく、例えば、液状の樹脂をスクリーン印刷法で回路の形成を予定する部分を除く部分に塗布した後、固化して形成したものや、液状又はシート状の感光性樹脂を無電解めっき被膜の表面全体に形成した後、回路形状に露光し、次いで、回路の形成を予定する部分の感光性樹脂を除去して形成したもの等が挙げられる。無電解めっき層とレジスト被膜との密着性を向上するために無電解めっき層表面の洗浄や粗化、酸化層の除去、あるいは酸化層の形成などを行うこともある。
（６）第一、第二金属層を給電層として電気めっきを行って、給電層が露出する部分の表面に、回路パターンを形成する。なお、このとき形成する回路パターンの厚みは、レジスト被膜の厚みより厚くても良く、薄くても良い。また、電気めっきに代えて、無電解めっきにより回路パターンをを形成するようにしても良い。
（７）レジスト被膜を除去する。レジスト剥離液は、用いるレジスト被膜によって適宜決められるものである。
（８）給電層をエッチング除去する。なおこの際、回路パターンを殆ど浸食せず、給電層のみを選択的にエッチングするエッチング液を用いる。すなわち、ニッケルまたはニッケル合金に対するエッチング速度が銅または銅合金にたいするエッチング速度の２倍以上であるエッチング液を用いる。これにより、回路パターンはエッチングされず、形成したときの状態がほぼ保たれる。そのため、回路形状はほぼ矩形を保つことができ、形状が優れた回路を得ることが可能になる。エッチング液の例としては、たとえば特開２００１−１４００８４に開示されているエッチング液が好適に用いられる。エッチング速度は、４０ｍｍ×４０ｍｍ×０．３ｍｍ（厚み）の金属板をエッチング液中に３分間浸漬、静置した際の重量減少から次式で算出する。
エッチング速度（μｍ／分）＝（重量減少）×10000／（表面積×金属板の密度×浸漬時間）ここで、金属板の密度：ニッケル＝８．８４５ｇ／ｃｍ³、銅＝８．９２ｇ／ｃｍ³、表面積：４×４×２＋４×０．０３×４＝３２．４８ｃｍ²、浸漬時間：３分である。
（９）必要に応じて無電解ニッケルめっきや無電解金めっきの仕上げ加工を行って、プリント配線板を製造する。
【００５９】
以上の工程を経ることで、本発明の積層体の特徴を充分に生かして多層プリント配線板を製造できる。特にビアホールの導通のためには無電解ニッケルめっきの触媒付与が必要となるが、ビアホール部以外は第１金属被膜上に触媒が付与しているため、第１金属被膜のエッチングによって不要部の触媒は容易に除去できる。
【００６０】
【実施例】
（実施例１）
厚み２５μｍのポリイミドフィルム（鐘淵化学製アピカルＨＰ）の片方の面にニッケルをＤＣマグネトロンスパッタリングして第一金属皮膜を形成した。
実験に用いたポリイミドフィルムの表面粗さ（Ｒｚ）は１μｍであった。また、代表的なスパッタリング条件はアルゴン圧０．２Ｐａ、放電電力４００Ｗ、２分間スパッタリングし、２００ｎｍのニッケル被膜を得た。
次いで、第一金属層全面に無電解ニッケルめっき被膜を得た。無電解ニッケルめっきの代表的なプロセスは、スパッタニッケル表面の脱脂、硫酸、過酸化水素水によるソフトエッチング、希硫酸によるスマット除去、希塩酸に予備浸漬、スパッタニッケル表面へパラジウム触媒付与、無電解ニッケルめっき（８０℃、１０分）を行った。この方法で無電解ニッケルめっきが約０．５μｍ析出した。
次いで、ニッケルめっき表面を１０重量％の硝酸に１０秒間浸漬した後、硫酸銅電気めっき（ハイスロー浴）により銅被膜を形成した。電気めっきは、室温，２Ａ／ｄｍ²、４０分の条件で厚み１８μｍの銅被膜を形成した。
ＪＩＳ Ｃ６４７１（引き剥がし強さ:Ｂ法）により、得られた積層体の金属層とポリイミドフィルムの接着強度（常態接着強度）を測定した結果、６〜８Ｎ／ｃｍであった。また、剥離界面は、スパッタニッケルとポリイミドフィルムの界面であった。また、得られた積層体を温度１２１℃、相対湿度１００％のプレッシャークッカーで９６時間曝露した後の接着強度（ＰＣＴ後接着強度）を測定した結果、４〜６Ｎ／ｃｍであった。また、剥離界面は、スパッタニッケルとポリイミドフィルムの界面であった。
【００６１】
（比較例１）実施例１と同様のポリイミドフィルムにスパッタにより銅薄膜を形成し、次いで無電解銅めっきを行った後、実施例１と同様の方法で電気銅めっき層を形成した。ポリイミドフィルムと金属層の常態接着強度は５〜７Ｎ／ｃｍ、ＰＣＴ後接着強度は１Ｎ／ｃｍ以下であった。また、剥離界面は、スパッタ銅とポリイミドフィルムの界面であった。
【００６２】
（比較例２）
実施例１と同様のポリイミドフィルム表面に、スパッタニッケル層、無電解銅めっき層、電気銅めっき層を形成した積層体を作製し、常態、ＰＣＴ後の接着強度を測定した。結果はともに１Ｎ／ｃｍ以下であった。また、剥離界面は、スパッタニッケルと無電解銅めっきの界面であった。
【００６３】
（実施例２）
実施例１の方法で作製した、ポリイミドフィルム／スパッタニッケル層からなる積層体を用いて以下の手順で多層プリント配線板を作製した。
（接着層の形成）窒素雰囲気下で容量２０００ｍｌのガラス製フラスコに、Ｎ，Ｎ−ジメチルホルムアミド（以下、ＤＭＦという。）に１当量のビス｛４−（３−アミノフェノキシ）フェニル｝スルホン(以下ＢＡＰＳ−Ｍという)を溶解した。溶液を氷水で冷却しつつ撹拌し、１当量の４、４´―（４、４´―イソプロピリデンジフェノキシ）ビス（無水フタル酸）（以下、ＢＰＡＤＡという）を溶解、重合し固形分濃度３０重量％のポリアミド酸重合体溶液を得た。
【００６４】
このポリアミド酸溶液を２００℃１８０分、６６５Ｐａの減圧下で２００℃３時間で減圧加熱し、固形の熱可塑性ポリイミド樹脂を得た。
上記で得たポリイミド樹脂とノボラック型のエポキシ樹脂（エピコート１０３２Ｈ６０：油化シェル社製）、および４，４’−ジアミノジフェニルスルフォン（以下、４，４’−ＤＤＳとする）を重量比が７０／３０／９になるように混合し、ジオキソランに固形分濃度が２０重量％になるように溶解して接着剤溶液を得た。得られた接着剤溶液を第一金属被膜を形成した積層体の該ポリイミドフィルムの他方の面に乾燥後の厚みが９μｍになるように塗布し、１７０℃で２分間乾燥して接着層を形成して、スパッタニッケル層／ポリイミドフィルム層／接着層からなる積層体を作製した。
（積層）得られたスパッタニッケル層／ポリイミドフィルム層／接着層からなる積層体の接着層を、銅箔９μｍのガラスエポキシ銅張積層板から作製した内層回路板の回路面対向させ、真空プレスにより２００℃２時間の条件でプリント配線板表面に積層、硬化した。
（穴開け）積層体の内層回路と外層回路を接続すべき位置にＵＶ−ＹＡＧレーザーにより直径５０μｍのビアホールの穴開けを行った。
（無電解めっき）実施例１と同様の方法でスパッタニッケル面上に無電解ニッケルめっきを施した。
（レジストパターニング）感光性ドライフィルムレジスト（旭化成製サンフォート）を１０５℃で熱ラミネートした後回路形状に露光した。なお回路形状としては、１５μｍの絶縁間隔を設けて形成した回路幅１５μｍの櫛型電極の形状に露光し、１重量％炭酸ナトリウム水溶液で現像した。
（電気銅めっき）ニッケルめっき表面を１０重量％の硝酸に１０秒間浸漬した後、硫酸銅電気めっき（ハイスロー浴）により銅被膜を形成した。電気めっきは、室温，１Ａ／ｄｍ²、４０分の条件で厚み９μｍの銅被膜を形成した。
（レジスト剥離）重量濃度３％の水酸化ナトリウム水溶液で残ったレジスト膜を剥離した。
（フラッシュエッチング）表１に示される組成のエッチング液を基板にスプレーしてニッケルの第一、第二金属被膜をエッチングし、回路幅１５μｍ、絶縁間隔１５μｍのパターンを作製した。
【００６５】
用いたエッチング液のエッチング速度は、ニッケルのエッチング速度＝５．３８μｍ／分、銅のエッチング速度＝０．０４μｍ／分であった。
【００６６】
【表１】

【００６７】
（比較例３）エポキシ樹脂両面銅張り積層板の表面の銅箔を全面エッチングした板の表面に、エポキシ樹脂をカーテンコーター法で塗布した後、１５０℃で１時間加熱して、表面樹脂層が半硬化状態である絶縁基板を得た。
【００６８】
次いで、上記絶縁基板に炭酸ガスレーザーにてビアホールを形成し、過マンガン酸カリウム溶液に浸漬して、樹脂層の表面を粗面化して、無電解めっきの密着性を向上させる処理を行った。粗化後の樹脂の表面粗さＲｚは４μｍであった。次いで、その樹脂層の表面に、パラジウム−スズコロイド型のめっき触媒を付与した後、無電解銅めっきを行い、絶縁基板の表面に、厚み０．５μｍの銅製第一金属皮膜を形成した。
【００６９】
次いで、第一金属皮膜の表面に実施例１と同様で回路の形成を予定する部分を除く部分にレジスト被膜を形成し、第一金属皮膜が露出する部分の表面に、厚み９μｍの銅製第二金属皮膜を形成した。
【００７０】
次いで、ハンダめっきを行って、第二金属皮膜の表面に、厚み３μｍのハンダ製金属皮膜（第三金属皮膜）を形成した。
【００７１】
次いで、アルカリ型の剥離液を用いてレジスト被膜を除去した後、アルカリエッチング液を絶縁基板の表面にスプレーして第一金属皮膜をエッチングし、次いで、ハンダ剥離液を用いて、第二金属皮膜の表面に形成したハンダ製の第三金属皮膜を除去して、第二金属皮膜を露出させた。
【００７２】
次いで、過マンガン酸カリウム溶液に絶縁基板を浸漬して、絶縁基板の表面の半硬化状態の樹脂層を除去すると共に、絶縁基板の表面に残留するめっき触媒を除去した後、１７０℃で２時間加熱して、半硬化状態の樹脂層を完全硬化させた。
（評価、結果）
実施例２及び比較例３で得られた多層プリント配線板の回路形状及び絶縁性を評価した。回路形状は、形成した櫛型電極の形状の回路のうち、回路幅１５μｍに露光した部分の回路幅を顕微鏡で、回路断面の形状が矩形であるか、また線状パターンの端部が直線状であるかを観察した。絶縁性は、形成した櫛型電極の形状の回路のうち、１５μｍの絶縁間隔を有して導通しない回路間の、絶縁抵抗を求めた。
その結果は、実施例２の製造方法は、比較例３と比べて回路形状、絶縁性が優れているプリント配線板を簡便に製造できることが確認された。
【００７３】
【発明の効果】
本発明に係る積層体は、表面の平滑な高分子フィルムの表面に物理的手法によって形成したニッケルまたはニッケル合金の第１金属層、無電解ニッケルめっきによる第２金属層および電気銅めっきによる第３の金属層からなり、高分子フィルムと金属層が強固に接着する。また、本発明にかかるプリント配線板の製造方法によれば、超高密度回路を形成するプリント配線板を簡便に製造できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminate in which a metal layer is formed on a polymer film having a smooth flat surface, which is widely used in electrical and electronic equipment, and more particularly to a laminate that is optimal for printed wiring board production. More specifically, a high-density printed wiring board manufactured by a semi-additive construction method, a laminate for a build-up multilayer printed wiring board to which the construction method can be applied, and using the laminate, the construction method is applied. It is related with the buildup multilayer printed wiring board manufactured in this way.
[0002]
[Prior art]
A printed wiring board having a circuit formed on its surface is widely used for mounting electronic components, semiconductor elements, and the like. With the recent demand for miniaturization and higher functionality of electronic devices, such printed wiring boards include There is a strong demand for higher density and thinner circuits. In particular, establishment of a fine circuit forming method in which the line / space spacing is 20 μm / 20 μm or less is an important issue in the field of printed wiring boards.
[0003]
As a method for producing this high-density printed wiring board, a method called a semi-additive method has been studied. As a typical example, a printed wiring board is produced by the following steps.
[0004]
After a plating catalyst such as a palladium compound is applied to the surface of the insulating substrate made of a polymer material, electroless copper plating is performed using the plating catalyst as a core to form a thin metal film on the entire surface of the insulating substrate 1. .
[0005]
Next, a resist film is applied to the surface of the copper film thus formed, and a portion of the resist film where a circuit is to be formed is removed. Thereafter, electrolytic copper plating is performed using the portion where the electroless plating film is exposed as a feeding electrode, and a second metal film is formed on the surface.
Next, after removing the resist film, the electroless copper plating film is removed by etching. At this time, the surface of the electrolytic copper plating film is also etched by the thickness of the electroless copper film, thereby reducing the thickness and width of the circuit pattern.
[0006]
Furthermore, if necessary, the surface of the formed circuit pattern is subjected to nickel plating gold plating to manufacture a printed wiring board.
[0007]
As described above, the semi-additive method is manufactured by etching a thin electroless copper film (first metal film), so it is compared with a method called a subtractive method in which a circuit is formed by etching a thick metal foil. Thus, a fine circuit can be formed with high accuracy.
[0008]
[Problems to be solved by the invention]
However, it has been clarified that this semi-additive method has the following problems.
The first is the problem of adhesion between the circuit electrode to be formed and the substrate. As described above, an electroless copper plating layer is formed between the substrate and the circuit electrode. As described above, since the electroless plating layer is formed from the catalyst as an active point, it should be considered that there is essentially no adhesion to the substrate. If the substrate surface has large irregularities, the adhesion during this time can be maintained well by the anchor effect, but naturally the adhesion tends to become weaker as the substrate surface becomes smoother.
For this reason, the semi-additive method requires a step of roughening the surface of the polymer film as the substrate, and the surface is usually provided with irregularities of about 3 to 5 μm in terms of Rz value. Such unevenness on the surface of the substrate is not a problem when the value of the line / space of the circuit to be formed is 30/30 μm or more, but for forming a circuit with a line width of 30/30 μm or less, particularly 20/20 μm or less. Is a serious problem. This is because such a high-density circuit line is affected by irregularities on the substrate surface.
Therefore, in order to form a circuit having a line / space value of 20/20 μm or less, a circuit formation technique on a polymer substrate having high surface smoothness is required, and its flatness is 2 μm or less, more preferably 1 μm in terms of Rz value. Must be: Naturally, in this case, the anchor effect becomes weak and cannot be expected as an adhesive force, so it is necessary to develop another bonding method.
The second problem of the semi-additive method is the etching process. Since the electroless plating layer used as the power feeding layer of the electroplating layer is an unnecessary layer for the circuit, it must be removed by etching after the electroplating layer is formed. However, when the electroless plated copper layer (first metal coating) is removed by etching, the circuit pattern of the electroplating layer (second metal coating) also decreases in width and thickness, and a precise circuit pattern is manufactured with good reproducibility. Is difficult.
In addition, as a third problem, since the plating catalyst tends to remain on the surface of the insulating substrate, the insulating property of the obtained printed wiring board is likely to be lowered, and further, when performing nickel plating or gold plating on the circuit in the final process, Another problem is that the surface of the insulating substrate is plated with nickel and gold by the catalytic action of the remaining plating catalyst, and a circuit cannot be formed.
Therefore, the plating catalyst on the surface of the insulating substrate is also removed at the same time by etching and removing the first metal film using an etching solution having a high etching ability.
[0009]
However, when the electroless plating layer is removed by etching using this etching solution having a high etching ability, the electroplating layer (second metal film) is affected, the width of the top portion of the circuit is narrowed, and the circuit shape is poor. There was a problem of becoming.
The object of the present invention is to form a strongly bonded copper conductive layer on a polymer substrate having excellent surface smoothness.
The present invention is a laminate of a polymer and a metal layer, which is made to improve the above-mentioned problems and can realize a high-density printed wiring board by a semi-additive method, and its purpose is adhesiveness, circuit shape An object of the present invention is to provide a printed wiring board excellent in insulation between lines.
[0010]
[Means for Solving the Problems]
The first feature of the laminate according to the present invention is that a nickel or nickel alloy layer formed by a physical method is formed.
The second feature of the laminate according to the present invention is that an electroless nickel plating layer is formed on a nickel or nickel alloy layer formed by a physical method. In order to increase the number of printed wiring boards, electroless plating is generally employed to form through holes or IVH (interstitial via holes) in the laminate and to make the holes conductive. The electroless nickel is firmly bonded to the nickel or nickel alloy layer by a physical method.
The third feature of the laminate according to the present invention is that the first layer made of nickel or a nickel alloy formed by a physical method, the second layer formed by electroless nickel plating, and the third layer formed by electro copper plating formed on the surface thereof. The point is that it consists of layers.
For printed wiring board applications, the first metal layer by physical means is firmly attached to a smooth insulating material, and the second metal layer by electroless nickel plating conducts well through holes and IVH of the printed wiring board. In addition, it firmly adheres to the first metal layer and also firmly adheres to the third metal layer formed by electrolytic copper plating. The third layer serving as the circuit portion is preferably copper or a copper alloy having a low electric resistance.
The fourth feature of the laminate according to the present invention is a laminate comprising a metal layer, an adhesive layer, and a polymer layer sandwiched between them, and nickel or nickel formed by a physical method. It is an alloy.
The fifth feature of the laminate according to the present invention is a laminate comprising a metal layer, an adhesive layer, and a polymer layer sandwiched between them, and nickel or nickel formed by a physical method. The first layer is an alloy and the second layer is an electroless nickel plating layer.
[0011]
The sixth feature of the laminate according to the present invention is a laminate comprising a metal layer, an adhesive layer, and a polymer layer sandwiched between them, and nickel or nickel formed by a physical method. It is in the point which consists of the 1st layer which is an alloy, the 2nd layer by the electroless nickel plating layer, and the electrolytic copper plating layer formed in the surface.
[0012]
The seventh feature of the laminate according to the present invention is that the physical method for forming the first layer is a sputtering method.
[0013]
The eighth feature of the laminate according to the present invention is that the thickness of the first layer is nickel or a nickel alloy having a thickness of 5 nm or more and 1000 nm or less.
[0014]
The ninth feature of the laminate according to the present invention is that the surface roughness of the polymer film is 2 μm or less in terms of Rz value.
[0015]
A tenth feature of the laminate according to the present invention is that the polymer film is a polyimide film.
The eleventh feature of the laminate according to the present invention is that the adhesive layer contains a polyimide resin.
[0016]
A feature of the method for producing a printed wiring board according to the present invention is that a circuit is formed using the laminate.
[0017]
Another feature of the method for producing a printed wiring board according to the present invention is that a resist film is formed on a portion excluding a portion on which a circuit is to be formed on the metal layer of the laminate according to claims 1, 2, 4, and 5. After that, electrolytic copper plating is performed to form a copper film on the surface where the metal layer is exposed, then the resist film is removed, and then the etching rate of nickel or nickel alloy is the etching rate of copper or copper alloy. The circuit is formed by etching and removing the nickel or nickel alloy layer using an etching solution twice or more of the above.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The laminate according to the present invention will be described.
[0019]
The polymer film used in the present invention is not particularly limited, and examples thereof include epoxy resins, phenol resins, polyimide resins, unsaturated polyester resins, polyphenylene ether resins, and other thermosetting resins. It is done. The polymer film may have a conductor circuit, a through hole, or the like. In order to improve the adhesion to the first metal layer, the surface of the insulating substrate may be subjected to various known surface treatments such as corona discharge treatment, plasma treatment, flame treatment, heat treatment, and primer treatment. It is also effective and preferable to add a known adhesion-imparting agent or surface treatment to the resin constituting the polymer film. Among these, from the viewpoint of heat resistance, flexibility, dimensional stability, dielectric constant, surface property, price, and the like, a polyimide resin type, an epoxy resin type, or a blend of these is preferable.
[0020]
The case where a polyimide film is used for the polymer film is described in detail below. A known manufacturing method can be applied to the polyimide film. That is, a polyamic acid polymer obtained by polymerizing in one or more tetracarboxylic dianhydride components and one or more diamine components in an organic polar solvent using substantially equimolar amounts. The solution is cast-coated on a support such as a glass plate or a stainless steel belt, and a polyamic acid film (hereinafter referred to as a gel film) partially imidized or partially dried to the extent that it has self-supporting properties is drawn from the support. It is obtained by peeling off, fixing the end by a method such as pin or clip, and further heating to imidize the polyamic acid completely.
[0021]
Known tetracarboxylic dianhydrides can be used as the tetracarboxylic dianhydride component used in the production of the polyamic acid polymer. Specifically, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 1 , 4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, 3,3 ′, 4,4 ′ -Dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ', 4,4'-tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4 '-Bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 4,4'-hexafluoroisopropylidene diphthalic anhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride , 2, 3, 3 '4'-biphenyltetracarboxylic dianhydride, p- aromatic such as phenylene anhydride tetracarboxylic dianhydride and the like.
[0022]
In order to obtain a polyimide film suitable for the use of the present invention, p-phenylenebis (trimellitic acid monoester anhydride) (hereinafter referred to as TMHQ) and pyromellitic dianhydride (hereinafter referred to as PMDA) are arbitrarily used. What mixed in the ratio is preferable. On the other hand, known diamines can be used as typical diamine components used in the production of the polyamic acid polymer. Specifically, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 2,2-bis (4-aminophenoxyphenyl) propane, 1,4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl) Sulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 9,9-bis (4-aminophenyl) fluorene, bisaminophenoxyketone, 4,4′- 1,4-phenylenebis (1-methylethylidene)) bisaniline, 4,4 ′-(1,3-phenylenebis (1-methylethylidene)) bisaniline, m-phenylenediamine, p-phenylenediamine, 4,4 ′ -Diaminobenzanilide, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethylbenzidine, 3,3'-dihydroxybenzidine And other aliphatic diamines.
[0023]
In order to obtain a polyimide film suitable for use in the present invention, paraphenylenediamine (hereinafter referred to as PDA) 4,4′-diaminobenzanilide (hereinafter referred to as DABA) and 4,4′-diaminodiphenyl ether (hereinafter referred to as ODA). Are preferably mixed at an arbitrary ratio.
[0024]
The combination of the tetracarboxylic dianhydride component and the diamine component described here is one specific example for obtaining the polyimide film of the present invention, and is not limited to these combinations. It is possible to adjust the characteristics of the polyimide film by changing the combination of the component and the diamine component and the use ratio.
[0025]
Examples of the organic polar solvent used for the formation reaction of the polyamic acid copolymer include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, Acetamide solvents such as N, N-dimethylacetamide and N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m-, or p -Phenolic solvents such as cresol, xylenol, halogenated phenol, catechol, hexamethylphosphoramide, γ-butyrolactone, etc. are preferable, and these are preferably used alone or as a mixture. Good like Some use of the family hydrocarbon are also possible.
[0026]
A known method can be applied to prepare a polyamic acid polymer solution using these raw materials. Specifically, a method of gradually adding the tetracarboxylic dianhydride component after dissolving the diamine component in the solvent, a method of simultaneously dissolving the diamine component and the tetracarboxylic dianhydride component in the solvent, the diamine component and the tetracarboxylic acid Examples thereof include a method of alternately dissolving the acid dianhydride component.
[0027]
When copolymerizing a polyamic acid polymer solution using three or more types of monomer raw materials, it is possible to control the order of addition of the respective raw materials to control the molecular arrangement within the polymer, and random copolymerization. Methods such as block copolymerization, partial block copolymerization, and sequential copolymerization have been proposed.
The average molecular weight of the polyamic acid that is a precursor of the polyimide film of the present invention is desirably 10,000 to 1,000,000. If the average molecular weight is less than 10,000, the resulting film may become brittle. On the other hand, when it exceeds 1,000,000, the viscosity of the polyamic acid varnish, which is a polyimide precursor, becomes too high, and the handling may be difficult.
In addition, in the polymerization of the polyamic acid polymer solution, a step such as filtration may be added for the purpose of removing foreign substances or high molecular weight substances in the polyamic acid polymer solution at any stage before, during or after polymerization. Is possible.
[0028]
Furthermore, in order to shorten the time required for the polymerization process, a first polymerization process for obtaining a so-called prepolymer having a low polymerization degree, and a second polymerization process for obtaining a high molecular weight polyamic acid polymer solution by increasing the polymerization degree. It is also possible to divide.
In particular, it is preferable from the viewpoint of polymerization efficiency and filtration efficiency to perform the second polymerization process after passing through a process such as filtration in the prepolymer stage after the first polymerization process.
[0029]
Further, it is desirable from the viewpoint of handling that the polyamic acid copolymer is dissolved in the organic polar solvent in an amount of 5 to 40% by weight, preferably 10 to 30% by weight.
As a method for forming the polyamic acid polymer solution obtained by the above method into a polyimide film, a known method can be applied. That is, the polyamic acid polymer solution is cast and coated on a support such as glass or stainless steel and partially imidized or partially dried to the extent that it has self-supporting properties (hereinafter referred to as a gel film). Is peeled off from the support, the end is fixed by a method such as pin or clip, and further heated to imidize the polyamic acid completely. At this time, before the polyamic acid is cast and applied, a dehydrating agent that accelerates the imidization reaction of the polyamic acid and a curing agent mixed with a catalyst and a solvent (hereinafter referred to as a chemical curing agent) are added to the polyamic acid solution, mixed, A so-called chemical curing method for stirring, a thermal curing method for thermally imidizing, a method using both in combination, and the like can be applied.
[0030]
From the viewpoints of film productivity and physical properties of the obtained film, a chemical cure method or a combination of a chemical cure method and a thermal cure method is preferable.
Moreover, a well-known surface treatment and post-processing can be applied to the polyimide film obtained by the said method. Specifically, embossing treatment, sandblasting treatment, corona discharge treatment, plasma discharge treatment, electron beam irradiation treatment, UV treatment, heat treatment, flame treatment, solvent cleaning treatment, primer treatment, chemical etching treatment and the like can be applied. Moreover, it is also possible to obtain a polyimide film after processing these gel films alone or in combination of a plurality of processes. In particular, a partially imidized or partially dried polyamic acid film (gel film) is selected from the group consisting of Al, Si, Ti, Mn, Fe, Co, Cu, Zn, Sn, Sb, Pb, Bi, and Pd. A method of completely drying the polyamic acid and imidizing it after immersion in a solution of a compound containing at least one element selected or applying the solution to the gel film is effective for improving the adhesiveness.
[0031]
The gel film is in the middle of drying and contains a solvent. This solvent content (volatile component content) is calculated from Equation 1.
[0032]
(AB) × 100 / B... Formula 1
In Formula 1, A and B represent the following.
A is the weight of the gel film
B is the weight after heating the gel film at 450 ° C. for 20 minutes.
The volatile component content is in the range of 5 to 300% by weight, preferably 5 to 100% by weight, more preferably 5 to 50% by weight.
[0033]
Moreover, the gel film is in the middle of the reaction from polyamic acid to polyimide, and the imidation ratio indicating the degree of progress of the reaction is calculated from Equation 2 using infrared absorption spectrometry.
[0034]
(C / D) × 100 / (E / F)... Formula 2
In Formula 2, C, D, E, and F represent the following.
C: 1370cm of gel film ^-1 Absorption peak height
D: 1500cm of gel film ^-1 Absorption peak height
E: 1370cm of polyimide film ^-1 Absorption peak height
F: 1500cm of polyimide film ^-1 Absorption peak height
The imidation ratio is in the range of 50% or more, preferably 70% or more, more preferably 80% or more, and most preferably 85% or more.
As the compound containing at least one element selected from the group consisting of Al, Si, Ti, Mn, Fe, Co, Cu, Zn, Sn, Sb, Pb, Bi, and Pd, an organic or inorganic compound containing the above element The following form is preferably used.
Specifically, examples of inorganic compounds include halides such as chloride and bromide, oxides, hydroxides, carbonates, nitrates, nitrites, phosphates, sulfates, silicates, borates, and condensations. A phosphate etc. are mentioned.
[0035]
Examples of organic compounds include organic compounds having neutral molecules such as alkoxides, acylates, chelates, diamines, diphosphines, acetylacetonate ions, carboxylate ions, dithiocarbamate ions, and cyclic ligands such as porphyrins. Etc.
[0036]
Among these, preferred elements are Si and Ti. Compounds containing these elements are given in the form of alkoxides, acylates, chelates or metal salts.
Among silicon compounds, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-aminopropyl Aminosilane compounds such as triethoxysilane and epoxysilane compounds such as β- (3,4 epoxy cyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane Compounds.
[0037]
The titanium compound is preferably represented by the general formula (Formula 1), specifically, tri-n-butoxy titanium monostearate, diisopropoxy titanium bis (triethanolaminate), butyl titanate dimer, tetranormal butyl titanate, Tetra (2-ethylhexyl) titanate, titanium octylene glycolate and the like are exemplified, and dihydroxybis (ammonium lactate) titanium, dihydroxytitanium bislactate and the like can also be used. Most preferred is tri-n-butoxy titanium monostearate or dihydroxy titanium bis-lactate.
[0038]
[Chemical 1]

[0039]
The solvent used for this solution should just dissolve the said compound. For example, water, toluene, xylene, tetrahydrofuran, 2-propanol, 1-butanol, ethyl acetate, N, N-dimethylformamide, acetylacetone and the like can be used. Two or more kinds of these solvents may be mixed and used, and a chemical curing agent component of polyamic acid may be mixed. In the present invention, N, N-dimethylformamide, 1-butanol, 2-propanol and water can be particularly preferably used.
[0040]
The concentration of the solution is preferably 0.01% to 10%, more preferably 0.1% to 5%. That is, the concentration of the element in the solution is preferably 1 ppm to 100,000 ppm, more preferably 10 ppm to 50,000 ppm.
[0041]
It is preferable to apply a step of removing excessive droplets on the surface of the gel film after applying or immersing the solution, so that a polyimide film having a uniform appearance on the film surface can be obtained. For removing the droplets, a known method such as a nip roll, an air knife or a doctor blade can be used, and a nip roll can be preferably used from the viewpoint of the appearance of the film, drainage, workability and the like.
Moreover, it is also possible to obtain a composite polyimide film by adding various organic additives, inorganic fillers, or various reinforcing materials at an arbitrary stage of producing the polyimide film.
[0042]
The polyimide film in the present invention is preferably 5 μm to 125 μm although the thickness is not limited. Particularly for use as a multilayer printed wiring board, the thickness of the polyimide film is 10 to 75 μm, preferably 10 to 50 μm, the tensile modulus is 4 GPa or more, preferably 6 GPa or more, more preferably 10 GPa or more, and the linear expansion coefficient is 17 ppm or less, preferably Suitable is 12 ppm or less, more preferably 10 ppm or less, and a water absorption of 2% or less, preferably 1.5% or less, more preferably 1% or less. A polymer film having a surface roughness Rz of 2 μm or less, preferably 1 μm or less is suitable for forming high-density wiring.
[0043]
As a method for forming the first metal film on the surface of the polymer film, a physical method such as a vacuum deposition method, a sputtering method, an ion plating method, or a CVD method is suitable. This is because it is not necessary to apply a plating catalyst to the insulating substrate, so that the plating catalyst does not remain after etching the first metal film, and surface roughening treatment (desmearing) is performed to improve adhesion like wet electroless plating. The reason for this is that the interface between the metal film and the insulating substrate is smooth, which has a good effect on the formation of narrow-spaced circuits and electrical characteristics. As a physical method, a sputtering method is preferable from the viewpoints of film formation productivity, adhesion to a polymer film, and the like. The thickness of the first metal film is preferably 5 nm to 1000 nm. If the thickness is less than 5 nm, the surface of the insulating substrate cannot be uniformly laminated, and sufficient adhesion between the insulating substrate and the metal layer cannot be obtained. In addition, when the thickness exceeds 1000 nm, not only is it not economical, but also the adhesive strength with the insulating substrate is reduced due to the internal stress difference between the first metal layer and the second metal layer. The alloy ratio increases and transmission characteristics deteriorate, it takes time to etch away the unnecessary first metal layer, the circuit pattern due to the second metal film is affected by etching, the circuit shape deteriorates, etc. Problem arises. After the first metal layer is formed, a removable protective film may be laminated on the surface of the first layer in order to prevent the first layer from being deteriorated and contaminated in the formation of the adhesive layer, lamination processing, and other processing steps. .
Next, through holes and IVH are drilled as necessary. These can be applied by punching, drilling, laser processing, a method using a photosensitive resin, a method by wet etching, a method by dry etching such as plasma, or the like alone or in combination. Laser processing, particularly UV-YAG laser and excimer laser are preferable from the viewpoints of fine processing, productivity, and the like.
A second metal layer is formed by electroless plating in order to conduct the formed through hole and IVH. Known electroless nickel plating can be applied as the electroless nickel plating.
The surface of the electroless plating film thus obtained is subjected to electrolytic copper plating. In effect, this electrolytic copper plating layer forms the circuit pattern of the printed wiring board. In order to improve the adhesion between electroless nickel plating and electroplating, the nickel surface may be cleaned, roughened, or the like.
[0044]
In addition, regarding the laminate in which the metal layer is formed on one side of the polymer film and the adhesive layer is formed on the other side, the type of the adhesive layer is not particularly limited, and a known resin is used. The adhesive can be broadly classified into (A) a heat-fusible adhesive using a thermoplastic resin and (B) a curable adhesive using a curing reaction of a thermosetting resin. These will be described below.
(A) Thermoplastic resins that give adhesives heat fusion are polyimide resins, polyamideimide resins, polyetherimide resins, polyamide resins, polyester resins, polycarbonate resins, polyketone resins, polysulfone resins, polyphenylene ether resins. , Polyolefin resin, polyphenylene sulfide resin, fluororesin, polyarylate resin, liquid crystal polymer resin, and the like. These may be used as an adhesive layer of the laminate of the present invention by appropriately combining one or more thereof. Among these, it is preferable to use a thermoplastic polyimide resin from the viewpoints of excellent heat resistance, electrical reliability, and the like.
[0045]
Here, a method for producing a thermoplastic polyimide resin will be described. The polyimide resin is obtained from a polyamic acid polymer solution that is a precursor thereof, and this polyamic acid polymer solution can be produced by a known method as described above. That is, it is obtained by using a substantially equimolar amount of a tetracarboxylic dianhydride component and a diamine component and polymerizing in an organic polar solvent. The acid dianhydride used for this thermoplastic polyimide resin will not be specifically limited if it is an acid dianhydride. Examples of the acid dianhydride component include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetra Carboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 3,5,6-tricarboxynorbonane-2-acetic acid dianhydride 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo Aliphatic or alicyclic tetracarboxylic dianhydrides such as [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; pyromellitic dianhydride; 3 3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,4′-oxyphthalic anhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3 ', 4,4'-Tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenyl sulfide Dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 4,4 ′ -F Safluoroisopropylidene diphthalic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid ) Phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4 ' Aromatic tetracarboxylic dianhydrides such as diphenyl ether dianhydride and bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride, 2,2-bis (4-hydroxyphenyl) propane dibenzoate-3 , 3 ', 4,4'-tetracarboxylic dianhydride, p-phenylenebis (trimellitic acid monoester anhydride), 4,4'-biphenylenebis Trimellitic acid monoester anhydride), 1,4-naphthalenebis (trimellitic acid monoester anhydride), 1,2-ethylenebis (trimellitic acid monoester anhydride), 1,3-trimethylenebis (tri Merit acid monoester anhydride), 1,4-tetramethylene bis (trimellitic acid monoester anhydride), 1,5-pentamethylene bis (trimellitic acid monoester anhydride), 1,6-hexamethylene bis ( Trimellitic acid monoester anhydride), 4,4 ′-(4,4′-isopropylidenediphenoxy) bis (phthalic anhydride) and the like are preferable. It can be used as part or all of the anhydride component.
[0046]
2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4,4′-tetracarboxylic dianhydride, 1,2-ethylene for the development of excellent heat-fusibility Bis (trimellitic acid monoester anhydride), 4,4′-hexafluoroisopropylidene diphthalic anhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalate It is preferable to use acid anhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 4,4 ′-(4,4′-isopropylidenediphenoxy) bis (phthalic anhydride).
[0047]
Examples of the diamine component include 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2, -bis [3- ( 3-aminophenoxy) phenyl] propane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, bis ( 4- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis (4-aminophenoxy) Phenyl) hexafluoropropane, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone 9,9-bis (4-aminophenyl) fluorene, bisaminophenoxyketone, 4,4 ′-(1,4-phenylenebis (1-methylethylidene)) bisaniline, 4,4 ′-(1,3- Phenylenebis (1-methylethylidene)) bisaniline, 3,3′-dimethylbenzidine, 3,3′-dihydroxybenzidine and the like can be mentioned, and these can be used alone or in combination of two or more. .
[0048]
Examples of the material for the thermoplastic polyimide resin used in the laminate of the present invention include 1,3-bis (3-aminophenoxy) benzene, 3,3′-dihydroxybenzidine, bis (4- (3-aminophenoxy) phenyl) sulfone. Are preferably used alone or in admixture at any ratio.
[0049]
A typical procedure for obtaining a polyamic acid polymer solution is a method of dissolving or diffusing one or more diamine components in an organic polar solvent and then adding one or more acid dianhydride components to obtain a polyamic acid solution Is mentioned. The order of addition of each monomer is not particularly limited, and the acid dianhydride component may be added to the organic polar solvent first, the diamine component may be added to form a polyamic acid polymer solution, and the diamine component may be added to the organic polar solvent. A suitable amount of the acid dianhydride component may be added first, and then an excess of the dianhydride component may be added, and a diamine component corresponding to the excess amount may be added to form a polyamic acid polymer solution. There are various other addition methods known to those skilled in the art. The term “dissolved” here refers to a state in which the solute is substantially dissolved by being uniformly dispersed or diffused in the solvent, in addition to the case where the solvent completely dissolves the solute. Including cases.
[0050]
Examples of the organic polar solvent used for the reaction for forming the polyamic acid solution include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, and N, N. -Acetamide solvents such as dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol, Phenol solvents such as xylenol, halogenated phenol and catechol, hexamethylphosphoramide, γ-butyrolactone and the like can be mentioned. If necessary, these organic polar solvents can be used in combination with aromatic hydrocarbons such as xylene and toluene.
[0051]
Next, a method for imidizing polyamic acid will be described.
[0052]
The imidization reaction of polyamic acid is a polyhydric acid dehydration cyclization reaction, and water is generated by the reaction. The generated water easily hydrolyzes the polyamic acid and causes a decrease in molecular weight. As a method of imidizing while removing water, usually 1) a method in which an azeotropic solvent such as toluene and xylene is added and removed by azeotropic distillation, 2) an aliphatic acid dianhydride such as acetic anhydride and triethylamine, pyridine, and picoline There are chemical imidization methods in which tertiary amines such as isoquinoline are added, and 3) imidization by heating under reduced pressure.
[0053]
The method of imidizing the thermoplastic polyimide resin of the present invention is preferably a method of imidizing by heating under reduced pressure. According to this imidization method, water generated by imidization can be positively removed from the system, so that hydrolysis of polyamic acid can be suppressed and a high molecular weight polyimide can be obtained. In addition, according to this method, one-sided or both-side ring-opened products existing as impurities in the raw acid dianhydride reclose, so that a further improvement in molecular weight can be expected.
[0054]
The heating condition of the method of heating imidization under reduced pressure is preferably 80 to 400 ° C., more preferably 100 ° C. or more, more preferably 120 ° C. or more, in which imidization is efficiently performed and water is efficiently removed. . The maximum temperature is preferably equal to or lower than the thermal decomposition temperature of the target polyimide, and a normal imidization completion temperature, that is, about 250 to 350 ° C. is usually applied.
[0055]
The condition for reducing the pressure is preferably as small as possible, but specifically 900 hPa or less, preferably 800 hPa or less, more preferably 700 hPa or less.
Further, as another method for obtaining a thermoplastic polyimide resin, there is a method in which the solvent is not evaporated in the thermal or chemical dehydration and ring closure method. Specifically, a polyimide resin solution obtained by performing a thermal imidization treatment or a chemical imidization treatment with a dehydrating agent is put into a poor solvent, and a polyimide resin is precipitated, and the unreacted monomer is removed and purified. It is a method of obtaining a solid polyimide resin by drying. As the poor solvent, a solvent having a property of being mixed well with the solvent but not easily dissolving the polyimide is selected, and examples thereof include acetone, methanol, ethanol, isopropanol, benzene, methyl cellosolve, methyl ethyl ketone, and the like. It is not limited. A thermoplastic polyimide resin can be obtained by these methods, and can be used as an adhesive layer of the laminate of the present invention.
[0056]
Next, (B) a curable adhesive using a curing reaction of a thermosetting resin will be described. Examples of thermosetting resins include bismaleimide resin, bisallyl nadiimide resin, phenol resin, cyanate resin, epoxy resin, acrylic resin, methacrylic resin, triazine resin, hydrosilyl cured resin, allyl cured resin, unsaturated polyester resin, etc. These can be used alone or in appropriate combination. In addition to the above thermosetting resins, side chain reactive group type thermosetting having reactive groups such as epoxy group, allyl group, vinyl group, alkoxysilyl group, hydrosilyl group, hydroxyl group at the side chain or terminal of the polymer chain. It is also possible to use a functional polymer as a thermosetting component.
The side chain reactive group type thermosetting polyimide resin will be described below. Specific production examples include (1) produced by a method according to the previously described thermoplastic polyimide resin, and in this case, epoxy group, vinyl group, allyl group, methacryl group, acrylic group, alkoxysilyl group, hydrosilyl group, A method of obtaining a thermosetting polyimide using a diamine component having a functional group such as a carboxy group, a hydroxyl group, a cyano group, or an acid dianhydride component as a monomer component, and (2) having a hydroxyl group, a carboxy group, an aromatic halogen group, etc. After producing the solvent-soluble polyimide according to the method for producing the thermoplastic polyimide resin already described, epoxy group, vinyl group, allyl group, methacryl group, acrylic group, alkoxysilyl group, hydrosilyl group, carboxy group, hydroxyl group, cyano group, etc. It is also possible to obtain a thermosetting polyimide resin by a method of imparting a functional group of That.
Necessary for improving thermosetting resin, radical reaction initiators such as organic peroxides, reaction accelerators, crosslinking aids such as triallyl cyanurate, triallyl isocyanurate, heat resistance, adhesion, etc. Depending on the above, generally used epoxy curing agents such as acid dianhydrides, amines and imidazoles, various coupling agents and the like can be added as appropriate.
[0057]
For the purpose of controlling the flowability of the adhesive during heat bonding, it is possible to mix a thermosetting resin with the thermoplastic resin. For this purpose, it is desirable to add 1 to 10,000 parts by weight, preferably 5 to 2000 parts by weight of the thermosetting resin with respect to 100 parts by weight of the thermoplastic resin. If the thermosetting resin is too much, the adhesive layer may become brittle, while if it is too little, the adhesive may protrude or the adhesiveness may be lowered.
As the adhesive used in the laminate of the present invention, a mixture of a thermoplastic polyimide resin and an epoxy resin is preferable because of a good balance of adhesion, workability, heat resistance, and the like.
[0058]
As a method for forming the adhesive layer on the polymer film, a known wet coating method can be applied. Specific examples include a gravure coater, a die coater, a curtain coater, a spin coater, a knife coater, and a spray coater. A gravure coater, a die coater, a curtain coater, etc. are suitable for continuous coating on a roll-shaped polymer film. In order to produce a multilayer printed wiring board using this laminate, the adhesive layer is, for example, in a semi-cured state (B stage state) in which the solvent component is evaporated without excessively proceeding the curing reaction.
The method of manufacturing a printed wiring board using the said laminated body can illustrate the following processes, for example.
(1) A first layer is formed on one surface of the polymer film by a physical method, and an adhesive layer is formed on the other surface.
(2) The laminated body is press laminated to the inner layer substrate with the inner layer circuit surface and the adhesive surface aligned. As the press lamination process, a vacuum press can be applied in addition to a single plate press, and vacuum press is preferable from the viewpoints of biting of bubbles during lamination, embedding of an inner layer circuit, prevention of oxidation of the first metal layer, and the like. The heating temperature is 180 ° C. to 200 ° C. for about 1 to 3 hours.
(3) A via hole is formed at a required position. For drilling via holes, laser drilling is effective for forming blind vias of small diameter vias, and a UV-YAG laser is suitable for drilling the entire first metal film.
(4) Conducting through holes and IVH formed by electroless nickel plating.
(5) A resist film is formed on a portion excluding a portion where a circuit is to be formed. The resist film used in the present invention is not particularly limited as long as it resists an electroplating solution for forming a circuit pattern and is difficult to form a second metal film on the surface when this plating is performed. For example, a liquid resin is applied to a portion other than a portion where a circuit is to be formed by screen printing, and then solidified, or a liquid or sheet-like photosensitive resin is applied to the entire surface of the electroless plating film. After forming, the circuit shape is exposed to light, and then formed by removing the photosensitive resin in the part where the circuit is to be formed. In order to improve the adhesion between the electroless plating layer and the resist film, the surface of the electroless plating layer may be washed or roughened, the oxide layer may be removed, or the oxide layer may be formed.
(6) Electroplating is performed using the first and second metal layers as a power feeding layer to form a circuit pattern on the surface of the portion where the power feeding layer is exposed. The circuit pattern formed at this time may be thicker or thinner than the resist film. Further, the circuit pattern may be formed by electroless plating instead of electroplating.
(7) The resist film is removed. The resist stripping solution is appropriately determined depending on the resist film to be used.
(8) The power feeding layer is removed by etching. At this time, an etchant that selectively etches only the power feeding layer without eroding the circuit pattern is used. That is, an etching solution having an etching rate with respect to nickel or a nickel alloy that is twice or more that of copper or a copper alloy is used. As a result, the circuit pattern is not etched, and the state when formed is substantially maintained. Therefore, the circuit shape can be kept substantially rectangular, and a circuit having an excellent shape can be obtained. As an example of the etching solution, for example, an etching solution disclosed in JP-A-2001-140084 is preferably used. The etching rate is calculated from the weight reduction when a 40 mm × 40 mm × 0.3 mm (thickness) metal plate is immersed in the etching solution for 3 minutes and left standing, according to the following equation.
Etching rate (μm / min) = (weight reduction) × 10000 / (surface area × metal plate density × dipping time) where metal plate density: nickel = 8.845 g / cm ^Three , Copper = 8.92 g / cm ^Three Surface area: 4 × 4 × 2 + 4 × 0.03 × 4 = 32.48 cm ² Soaking time: 3 minutes.
(9) A printed wiring board is manufactured by performing finish processing of electroless nickel plating or electroless gold plating as necessary.
[0059]
Through the above steps, a multilayer printed wiring board can be produced by fully utilizing the characteristics of the laminate of the present invention. In particular, it is necessary to apply a catalyst for electroless nickel plating for the conduction of via holes. However, since the catalyst is applied on the first metal coating except for the via holes, the catalyst for unnecessary portions is etched by etching the first metal coating. Can be easily removed.
[0060]
【Example】
(Example 1)
A first metal film was formed by DC magnetron sputtering of nickel on one surface of a 25 μm thick polyimide film (Apical HP manufactured by Kaneka Chemical).
The surface roughness (Rz) of the polyimide film used in the experiment was 1 μm. Typical sputtering conditions were an argon pressure of 0.2 Pa, a discharge power of 400 W, and sputtering for 2 minutes to obtain a 200 nm nickel coating.
Next, an electroless nickel plating film was obtained on the entire surface of the first metal layer. Typical processes for electroless nickel plating include degreasing the sputtered nickel surface, soft etching with sulfuric acid and hydrogen peroxide, smut removal with dilute sulfuric acid, pre-soaking in dilute hydrochloric acid, applying palladium catalyst to the sputtered nickel surface, electroless nickel plating (80 ° C., 10 minutes). By this method, about 0.5 μm of electroless nickel plating was deposited.
Next, the nickel plating surface was immersed in 10 wt% nitric acid for 10 seconds, and then a copper film was formed by copper sulfate electroplating (high throw bath). Electroplating is room temperature, 2A / dm ² A copper film having a thickness of 18 μm was formed under the conditions of 40 minutes.
It was 6-8 N / cm as a result of measuring the adhesive strength (normal adhesive strength) of the metal layer of the obtained laminated body, and a polyimide film by JISC6471 (peeling strength: B method). Moreover, the peeling interface was an interface between sputtered nickel and a polyimide film. Moreover, as a result of measuring the adhesive strength (exposure strength after PCT) after exposing the obtained laminated body for 96 hours with a pressure cooker with a temperature of 121 ° C. and a relative humidity of 100%, it was 4 to 6 N / cm. Moreover, the peeling interface was an interface between sputtered nickel and a polyimide film.
[0061]
Comparative Example 1 A copper thin film was formed on the same polyimide film as in Example 1 by sputtering, followed by electroless copper plating, and then an electrolytic copper plating layer was formed in the same manner as in Example 1. The normal adhesive strength between the polyimide film and the metal layer was 5 to 7 N / cm, and the post-PCT adhesive strength was 1 N / cm or less. The peeling interface is spattered. copper And the polyimide film interface.
[0062]
(Comparative Example 2)
A laminate in which a sputtered nickel layer, an electroless copper plating layer, and an electrolytic copper plating layer were formed on the same polyimide film surface as in Example 1 was prepared, and the adhesive strength after normal and PCT was measured. Both results were 1 N / cm or less. Further, the peeling interface was an interface between sputtered nickel and electroless copper plating.
[0063]
(Example 2)
A multilayer printed wiring board was produced by the following procedure using the laminate made of the polyimide film / sputtered nickel layer produced by the method of Example 1.
(Formation of adhesion layer) In a glass flask having a volume of 2000 ml under a nitrogen atmosphere, 1 equivalent of bis {4- (3-aminophenoxy) phenyl} sulfone (hereinafter referred to as N, N-dimethylformamide (hereinafter referred to as DMF)). BAPS-M) was dissolved. The solution was stirred while cooling with ice water, and 1 equivalent of 4,4 ′-(4,4′-isopropylidenediphenoxy) bis (phthalic anhydride) (hereinafter referred to as BPADA) was dissolved and polymerized to obtain a solid concentration of 30 A weight percent polyamic acid polymer solution was obtained.
[0064]
This polyamic acid solution was heated under reduced pressure at 200 ° C. for 3 hours at 200 ° C. for 180 minutes under a reduced pressure of 665 Pa to obtain a solid thermoplastic polyimide resin.
The weight ratio of the polyimide resin obtained above and a novolak epoxy resin (Epicoat 1032H60: manufactured by Yuka Shell) and 4,4′-diaminodiphenylsulfone (hereinafter referred to as 4,4′-DDS) is 70 / The mixture was mixed to 30/9 and dissolved in dioxolane so that the solid concentration was 20% by weight to obtain an adhesive solution. The obtained adhesive solution was applied to the other surface of the polyimide film of the laminate on which the first metal film was formed so that the thickness after drying was 9 μm, and dried at 170 ° C. for 2 minutes to form an adhesive layer. And the laminated body which consists of a sputter nickel layer / polyimide film layer / adhesion layer was produced.
(Lamination) Adhesive layer of laminate obtained from sputtered nickel layer / polyimide film layer / adhesive layer was made to oppose the circuit surface of the inner circuit board made from glass epoxy copper clad laminate of 9 μm copper foil, and by vacuum press It was laminated and cured on the surface of the printed wiring board at 200 ° C. for 2 hours.
(Drilling) A via hole having a diameter of 50 μm was drilled by a UV-YAG laser at a position where the inner layer circuit and the outer layer circuit of the laminate were to be connected.
(Electroless plating) Electroless nickel plating was performed on the sputtered nickel surface in the same manner as in Example 1.
(Resist patterning) A photosensitive dry film resist (Sunfort manufactured by Asahi Kasei) was heat laminated at 105 ° C. and then exposed to a circuit shape. The circuit shape was exposed to the shape of a comb-shaped electrode having a circuit width of 15 μm formed with an insulating interval of 15 μm, and developed with a 1 wt% aqueous sodium carbonate solution.
(Electro copper plating) After the nickel plating surface was immersed in 10 wt% nitric acid for 10 seconds, a copper film was formed by copper sulfate electroplating (high throw bath). Electroplating is room temperature, 1 A / dm ² A copper film having a thickness of 9 μm was formed under the conditions of 40 minutes.
(Resist stripping) The remaining resist film was stripped with an aqueous sodium hydroxide solution having a weight concentration of 3%.
(Flash Etching) An etching solution having the composition shown in Table 1 was sprayed on the substrate to etch the first and second metal films of nickel, thereby producing a pattern having a circuit width of 15 μm and an insulation interval of 15 μm.
[0065]
The etching rates of the etching solutions used were nickel etching rate = 5.38 μm / min and copper etching rate = 0.04 μm / min.
[0066]
[Table 1]

[0067]
(Comparative Example 3) An epoxy resin was applied by a curtain coater method to the surface of a board obtained by etching the entire surface of the copper foil on the double-sided copper-clad laminate of epoxy resin, and then heated at 150 ° C for 1 hour, An insulating substrate in a semi-cured state was obtained.
[0068]
Next, a via hole was formed in the insulating substrate with a carbon dioxide gas laser and immersed in a potassium permanganate solution to roughen the surface of the resin layer, thereby performing a treatment to improve the electroless plating adhesion. The surface roughness Rz of the resin after roughening was 4 μm. Next, after a palladium-tin colloidal type plating catalyst was applied to the surface of the resin layer, electroless copper plating was performed to form a copper first metal film having a thickness of 0.5 μm on the surface of the insulating substrate.
[0069]
Next, a resist film is formed on the surface of the first metal film in the same manner as in Example 1 except for the part where the circuit is scheduled to be formed, and a second copper 9 μm thick is formed on the surface of the part where the first metal film is exposed. A metal film was formed.
[0070]
Subsequently, solder plating was performed to form a solder metal film (third metal film) having a thickness of 3 μm on the surface of the second metal film.
[0071]
Next, after removing the resist film using an alkali type stripping solution, the first metal film is etched by spraying an alkali etching solution onto the surface of the insulating substrate, and then the second metal film is formed using a solder stripping solution. The third metal film made of solder formed on the surface was removed to expose the second metal film.
[0072]
Next, the insulating substrate is immersed in a potassium permanganate solution to remove the semi-cured resin layer on the surface of the insulating substrate, and the plating catalyst remaining on the surface of the insulating substrate is removed, and then at 170 ° C. for 2 hours. The semi-cured resin layer was completely cured by heating.
(Evaluation results)
The circuit shape and insulation of the multilayer printed wiring board obtained in Example 2 and Comparative Example 3 were evaluated. As for the circuit shape, the circuit width of the part exposed to a circuit width of 15 μm in the formed comb-shaped electrode circuit is a microscope, the circuit cross-sectional shape is rectangular, or the end of the linear pattern is linear Was observed. For the insulation, the insulation resistance between non-conducting circuits having an insulation interval of 15 μm among the formed comb-shaped electrodes was determined.
As a result, it was confirmed that the manufacturing method of Example 2 can easily manufacture a printed wiring board that is superior in circuit shape and insulation compared to Comparative Example 3.
[0073]
【The invention's effect】
The laminate according to the present invention includes a first metal layer of nickel or a nickel alloy formed by a physical method on the surface of a smooth polymer film, a second metal layer formed by electroless nickel plating, and a third layer formed by electrolytic copper plating. The polymer film and the metal layer are firmly bonded. Moreover, according to the method for manufacturing a printed wiring board according to the present invention, a printed wiring board for forming an ultra-high density circuit can be easily manufactured.

Claims (9)

A laminate comprising a polymer film and at least a metal layer formed on one surface thereof,
The metal layer is a first metal layer made of nickel or a nickel alloy formed by a physical method on the surface of the polymer film, and a second electroless nickel plating layer formed on the first metal layer. A laminate comprising a metal layer and a third metal layer made of an electrolytic copper plating layer formed on the surface of the second metal layer . A laminate comprising a metal layer, an adhesive layer, and a polymer film sandwiched therebetween, wherein the metal layer is nickel or a nickel alloy formed on the surface of the polymer film by a physical method. A metal layer, a second metal layer formed by an electroless nickel plating layer formed on the surface of the first metal layer, and a third metal layer formed by an electrolytic copper plating layer formed on the surface of the second metal layer. A laminate characterized by comprising: The laminate according to claim 2, wherein the adhesive layer contains a polyimide resin . The laminate according to any one of claims 1 to 3, wherein the first metal layer is nickel or a nickel alloy formed by a sputtering method . The laminate according to any one of claims 1 to 4, wherein the first metal layer has a thickness of 5 nm or more and 500 nm or less . The laminate according to any one of claims 1 to 5, wherein the surface roughness of the polymer film is 2 µm or less in terms of Rz value . The laminate according to any one of claims 1 to 6, wherein the polymer film is a polyimide film . The manufacturing method of the printed wiring board which forms a circuit using the laminated body of any one of Claims 1 thru | or 7 .   (I) A laminate comprising a polymer film and a metal layer formed on at least one surface thereof, wherein the metal layer is a nickel or nickel alloy formed on the surface of the polymer film by a physical technique. A laminate comprising a first metal layer and a second metal layer formed by an electroless nickel plating layer formed on the first metal layer, or
  (Ii) A nickel or nickel alloy comprising a metal layer, an adhesive layer, and a polymer film sandwiched between them, wherein the metal layer is formed on the surface of the polymer film by a physical technique. And a second metal layer formed by an electroless nickel plating layer formed on the first metal layer.
After forming the resist film on the part of the metal layer except the part where the circuit is scheduled to be formed, electrolytic copper plating is performed to form a copper film on the surface of the part where the metal layer is exposed, and then the resist film is formed. A method of manufacturing a printed wiring board that removes and then forms a circuit by etching away the nickel or nickel alloy layer using an etchant having an etching rate of nickel or nickel alloy twice or more that of copper or copper alloy .