JP3660733B2 - Photosensitive film material for circuit board insulation, flexible printed wiring board using the same, and sequential multilayer board - Google Patents

Description

【００１０】
（式中、Ｘは２価の基又は不存在を表し、ｎは１〜１０の数を表す。また、Ｒ₁ 〜Ｒ₈ は水素原子、アルキル基又はハロゲン原子を表し、各々が同一でも異なっていてもよく、Ｒ₉ は水素原子又はメチル基を表す。）
【００１１】
（１）式におけるＸとしては、例えば、メチレン基、２−プロピリデン基、２−（ヘキサフルオロ）プロピリデン基、カルボニル基、エーテル基、スルフォン基等の２価の基又は直結合があげられるが、好ましくは、２−プロピリデン基又は直結合である。また、Ｒ₁ 〜Ｒ₈ としては、水素原子、例えば、メチル基、エチル基、プロピル基、イソプロピル基等のアルキル基、例えば、塩素、臭素等のハロゲン原子があげられるが、好ましくは、水素又は臭素である。ｎは平均の繰り返し数を表し、１〜１０の数であるが、好ましくは、１〜２である。
【００１２】
特に、エポキシアクリレート化合物の一部又は全部として、Ｘが２−プロピリデン基であるビスフェノールＡ型エポキシアクリレート化合物を用いることにより、本発明の感光性フィルム材料にパターニングやその後の熱硬化などの処理を施して、最終的に得られるフィルムの耐熱性や機械的特性を向上させることができる。
【００１３】
また、本発明のオリゴマー製造に使用される酸無水物としては、例えば、無水フタル酸、テトラヒドロ無水フタル酸、ヘキサヒドロ無水フタル酸などのジカルボン酸無水物類や、例えば、無水ピロメリット酸、ビフェニルテトラカルボン酸二無水物、ベンゾフェノンテトラカルボン酸二無水物、ジフェニルスルフォンテトラカルボン酸二無水物、ジフェニルエーテルテトラカルボン酸二無水物、エチレングリコールビストリメリテート二無水物などのテトラカルボン酸二無水物、さらには無水トリメリット酸などがあげられる。また、これらの酸無水物はそれぞれ単独で用いてもよく、また、二種類以上の酸無水物を組み合わせて用いても差し支えない。そして、好ましくは、エチレングリコールビストリメリテート二無水物を酸無水物として全部又は一部用いることであり、これにより、最終的に得られるフィルムの柔軟性などの機械的な特性が向上する。
【００１４】
上記のエポキシアクリレート化合物と上記の酸無水物とを反応させて、本発明の必須成分のひとつであるオリゴマーを製造することができる。本発明のオリゴマーの重量平均分子量は、５００〜１，０００，０００、好ましくは、７００〜５００，０００、より好ましくは、１，０００〜１００，０００のものである。重量平均分子量が５００より小さいと最終的に得られるフィルムの機械的な特性が悪くなり、１，０００，０００より大きいとアルカリ水溶液によるパターン形成を行うことが困難となる。
【００１５】
本発明の感光性フィルム材料は、上記オリゴマーに加えて、エポキシ基を有する化合物を必須成分とする。ここでいうエポキシ基を有する化合物としては、例えば、ビスフェノールＡ型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂、フェノールノボラック型エポキシ樹脂、オルソクレゾールノボラック型エポキシ樹脂やそれらの臭素化物など、エポキシ基を有するものであれば任意のものを用いることが可能である。そして、このエポキシ基を有する化合物の一部又は全部に臭素化されたエポキシ基を有する化合物を用いることで、本発明の感光性フィルム材料に難燃性を付与することができる。
【００１６】
本発明における前記オリゴマーとエポキシ基を有する化合物との重量比率、すなわち、オリゴマー／エポキシ基を有する化合物の比率は、０．１〜１０であり、好ましくは、０．２〜５である。この比率が０．１に満たないとアルカリ性水溶液によるパターニングを行うことが困難となり、１０を超えると、耐熱性や耐薬品性が低下する。
【００１７】
ついで、前記オリゴマー及びエポキシを必須成分とする組成物をフィルム状に形成することにより本発明の感光性フィルム材料を完成することができる。ここでいうフィルム状とは、フィルム単体のみならず、高分子フィルム、金属箔などの最終的に剥離等の操作により除去される支持基材上に形成されたフィルム状のものも意味するが、恒久的に基材上に形成されたフィルムや塗膜は含まない。また、支持基材上に形成された本発明の感光性フィルム材料を、異物の付着やキズの発生等を防止するために、高分子フィルム等で保護することも可能である。
【００１８】
また、本発明の感光性フィルム材料に種々の特性を付与するために、他の成分としてアミン、光重合開始剤、光増感剤、多官能アクリレートのようなモノマー類、めっき用触媒、インジウムとスズの共酸化物又はシリカ等のフィラー類などをあらかじめ添加することも可能である。さらに、パターン形成前の感光性フィルムの流動性を改善するために、溶剤を含有させておくことも可能である。
【００１９】
また、上記組成物をフィルム状に形成する方法は公知の方法でよい。例えば、上記組成物を溶媒中に溶解又は分散させ、ダイコーター、ナイフコーター、リバースロールコーターなど任意の塗工装置を用いて支持基材の上に塗布後、溶媒を蒸発させてフィルムの形状に形成することができる。支持基材としてはポリエチレンテレフタレートなどの高分子フィルムや金属箔などが使用できる。また、必要に応じて構成の異なる２種類以上の組成物を用いて、２層以上の多層の感光性フィルム材料とすることも可能である。
【００２０】
このようにして得られた本発明の感光性フィルム材料は、アルカリ性の水溶液で非常に精度のよいパターニングが可能であり、また、耐熱性や機械的な特性をも兼ね備えているため、種々の用途に使用することができる。
【００２１】
本発明の感光性フィルム材料の好適な用途としては、フレキシブルプリント配線板用カバーレイがあげられる。つまり、本発明の感光性フィルム材料はラミネートという簡単な操作で、フレキシブルプリント配線板上に回路の保護を目的としたカバーレイと呼ばれる絶縁層を形成でき、精度の良いパターニングはもちろんのこと、半田づけなどの工程への十分な耐熱性や優れた耐折曲げ性等を備えているためである。
【００２２】
本発明の回路基板絶縁用感光性フィルム材料をカバーレイとするフレキシブルプリント配線板は、以下に示す必須工程を経て製造することができる。
（１）フレキシブルプリント配線板用金属張積層板に回路形成を施す工程、
（２）本発明の感光性フィルム材料を回路形成の施されたフレキシブルプリント配線板用金属張積層板上にラミネートする工程、
（３）露光及びアルカリ性水溶液による現像処理を行って、ラミネートされた感光性フィルム材料に開口部を形成する工程、
（４）１００〜３００℃の温度で１分以上の熱処理を行う工程。
【００２３】
上記した必須工程のほかに、必要に応じて、洗浄、乾燥、穴あけ又はめっき等を行うことはもちろん可能である。また、フレキシブルプリント配線板用金属張積層板としては、片面金属張積層板と両面金属張積層板のいずれにも適用可能である。
【００２４】
また、本発明の感光性フィルム材料の他の好適な用途として、導体回路上への絶縁層の形成とスパッッタリングやめっき等による新たな導体回路層の形成の繰り返しにより得られる、通称、ビルドアップ基板と呼ばれる逐次多層基板の導体間の絶縁材料があげられる。これは、本発明の感光性フィルム材料が、前記の耐熱性や機械的な特性に加え、スパッタリングやめっき処理工程への耐性をも備えているためである。
【００２５】
本発明の回路基板絶縁用感光性フィルム材料を絶縁材料とする逐次多層基板は以下に示す必須工程を経て製造することができる。
（１）絶縁性基材上に導体回路が形成された材料を作製する工程、
（２）本発明の感光性フィルム材料を導体回路が形成された材料上にラミネートする工程、
（３）露光及びアルカリ性水溶液による現像処理を行って、ラミネートされた感光性フィルム材料に開口部を形成する工程、
（４）１００〜３００℃の温度で１分以上の熱処理を行って、現像されたフィルム材料を硬化させる工程、
（５）めっき、スパッタリング、蒸着又はそれらの組み合わせにより、硬化させたフィルム上に次の導体回路層を形成する工程。
【００２６】
ここで用いる絶縁基材上に導体回路が形成された材料は、片面又は両面金属張積層板を出発材料としてエッチング法により作製することも可能であり、ガラスクロスと高分子の複合材料や高分子フィルムの片面又は両面に、めっき、スパッタリング、蒸着等の方法により、直接導体回路を形成して作製することも可能である。また、上記工程のうち、（２）〜（５）の工程を繰り返し行うことで、３層以上の導体層が形成された逐次多層基板を製造することが可能である。
【００２７】
【実施例】
以下、実施例に基づいて、本発明を具体的に説明するが、本発明はこれに限定されるものではない。
【００２８】
合成例１
ビスフェノールＡ型エポキシ樹脂（東都化成株式会社製、エポトートＹＤ−８１２５、エポキシ当量１７２ｇ／eq, ）３４．０重量部、アクリル酸１４．４重量部、臭化テトラエチルアンモニウム０．０５重量部及び溶媒としてエチルセルソルブアセテート５．８５重量部をフラスコ中に仕込み、撹拌して均一な溶液とした。この溶液を１０５℃で１５時間反応させてエポキシアクリレート化合物を得た。ついで、その反応溶液に、酸無水物として１，２，３，６−テトラヒドロ無水フタル酸７．６重量部及びエチレングリコールビストリメリテート二無水物２０．５重量部を添加し、１１５℃で５時間反応させて粘稠なオリゴマー溶液を得た。得られたオリゴマーのＧＰＣ分析による重量平均分子量は２，５００であった。
【００２９】
合成例２
合成例１の１，２，３，６−テトラヒドロ無水フタル酸７．６重量部とエチレングリコールビストリメリテート二無水物２０．５重量部の代わりに、エチレングリコールビストリメリテート二無水物４１．０重量部のみを用いて、合成例１と同様に合成を行った。得られたオリゴマーの重量平均分子量は３，８００であった。
【００３０】
合成例３
合成例１のエチレングリコールビストリメリテート二無水物２０．５重量部の代わりに、ビフェニルテトラカルボン酸二無水物１４．７重量部を用いて、合成例１と同様に合成を行った。得られたオリゴマーの重量平均分子量は１，８００であった。
【００３１】
合成例４
合成例１のビスフェノールＡ型エポキシ樹脂（東都化成株式会社製、エポトートＹＤ−８１２５）３４．０重量部の代わりに、エポキシ当量の異なるビスフェノールＡ型エポキシ樹脂（東都化成株式会社製、エポトートＹＤ−１２８、エポキシ当量１９２ｇ／eq, ）３８．０重量部を用い、溶媒としてエチルセルソルブアセテートを７．５０重量部を用いて、合成例１と同様に合成を行った。得られたオリゴマーの重量平均分子量は６，５００であった。
【００３２】
合成例５
ビスフェノールＡ型エポキシ樹脂（東都化成株式会社製、エポトートＹＤ−８１２５）３４．０重量部、アクリル酸１４．４重量部、臭化テトラエチルアンモニウム０．０５重量部及びエチルセルソルブアセテート５．８５重量部をフラスコ中に仕込み、撹拌して均一な溶液とした。ついで、１０５℃で１５時間反応させてエポキシアクリレート化合物を得た。得られた化合物の分子量は４８４であった。この化合物に対しては酸無水物との反応は行わなかった。
【００３３】
実施例１
合成例１で得られたオリゴマー溶液５０重量部に光重合開始剤（チバガイギー株式会社製、イルガキュア６５１）１重量部及びビスフェノールＡ型エポキシ樹脂（東都化成株式会社製、エポトートＹＤ−９０１）２８．７重量部を添加して感光性の組成物を得た。この組成物をアプリケーターを用いて、表面に離型処理を施した厚み５０μm のポリエチレンテレフタレート（ＰＥＴ）フィルム上に塗布し、６０℃で３０分間乾燥させて、実質的にタックのない厚み５０μm の感光性フィルムを作製した。ついで、この感光性フィルムを最小回路幅１００μm 、最小回路間１００μm の形状に回路形成された片面銅張積層板（新日鐵化学株式会社製、エスパネックスＳＣ３５−４０−００ＭＥ（電解箔３５μm ／ポリイミド４０μm ））上にＰＥＴフィルムを貼り合わせたまま、感光性フィルムと片面銅張積層板の回路面が接するように、ホットラミネーター装置（大成ラミネーター株式会社製、Ｍｏｄｅｌ ８Ｂ−５５０、温度８０℃、送り速度：１ｍ／分）を用いてラミネートした。その際、感光性フィルムは回路間にも空隙なく充填された。
【００３４】
次に、露光機（ハイテック株式会社製、ＨＴＥ−３０００ＮＥＬ）を用い、最小未露光部が直径１００μm となるフォトマスクを通して感光性フィルムを３００ｍＪの露光量で露光した。その後、ＰＥＴフィルムを剥離し、５％炭酸ナトリウム水溶液を用いて４０℃で１分間の現像処理を行った後、純水で洗浄し、１８０℃で６０分間熱処理を行って、パターン形成がなされた感光性フィルムがカバーレイとして構成されているフレキシブルプリント配線板を得た。得られたフレキシブルプリント配線板のカバーレイのパターン精度は、フォトマスクの最小未露光部の直径１００μm に対して１０２μm と優れたものであった。
【００３５】
得られたフレキシブルプリント配線板を２６０℃の半田浴に１分間浸漬したところ、ふくれ、はがれ等の異常は認められなかった。また、フレキシブルプリント配線板に対して１８０度の折曲げを行っても、クラックの発生は認められなかった。
【００３６】
実施例２
オリゴマー成分として合成例２で得られたオリゴマー溶液５０重量部を用い、現像処理条件を５％炭酸ナトリウム４０℃１分から２％炭酸ナトリウム４０℃１分に変更した以外は実施例１と同様に処理した。感光性フィルムの回路への充填性は良好であり、パターン精度は１０３μm と優れたものであった。また、得られたフレキシブルプリント配線板は半田浴に浸漬しても何ら異常を示さず、耐折曲げ性も優れたものであった。
【００３７】
実施例３
オリゴマー成分として合成例３で得られたオリゴマー溶液５０重量部を用い、実施例１と同様に行った。感光性フィルムの回路への充填性は良好であり、パターン精度は１０５μm と優れたものであった。また、得られたフレキシブルプリント配線板は半田浴に浸漬しても何ら異常を示さず、耐折曲げ性も優れたものであった。
【００３８】
実施例４
実施例１で用いた組成物に、さらにトリエチレングリコールジアクリレート５重量部を添加して、実施例１と同様に処理した。感光性フィルムの回路への充填性は良好であり、パターン精度は１０１μm と優れたものであった。また、得られたフレキシブルプリント配線板は半田浴に浸漬しても何ら異常を示さず、耐折曲げ性も優れたものであった。
【００３９】
実施例５
合成例４で得られたオリゴマー溶液５０重量部に、臭素化ビスフェノールＡ型エポキシ樹脂（東都化成株式会社製、エポトートＹＤＢ−４００）２６．５重量部、光重合開始剤（チバガイギー株式会社製、イルガキュア６５１）１重量部及びトリエチレングリコールジアクリレート５重量部を添加し、１時間撹拌して均一な組成物を得た。ついで、この組成物をアプリケーターを用いて、表面に離型処理を施した厚み５０μm のポリエチレンテレフタレート（ＰＥＴ）フィルムに塗布し、８０℃で５分間乾燥して、実質的にタックのない厚み４０μm の感光性フィルムを作製した。これとは別に、両面銅張積層板（新日鐵化学株式会社製、エスパネックスＳＢ３５−５０−３５ＨＲ（銅箔３５μm ／ポリイミド５０μm ））に最小回路幅１００μm 、最小回路間１００μm になるように回路形成を行った。この回路形成を行った両面銅張板の両面に感光性フィルムを、実施例１で用いたホットラミネーター装置を使ってラミネートした。その際、回路間への充填性は良好であった。
【００４０】
次に、実施例１で用いた露光機を使って、最小未露光部が直径１００μm となるフォトマスクを通して両側の感光性フィルムを２５０ｍＪの露光量で露光した。その後、ＰＥＴフィルムを剥離し、５％炭酸ナトリウム水溶液を用いて４０℃で１分間の現像処理を行った後、純水で洗浄し、２００℃で３０分間熱処理を行って、パターン形成がなされた感光性フィルムがカバーレイとして構成されている両面フレキシブルプリント配線板を得た。得られたフレキシブルプリント配線板のカバーレイのパターン精度は、フォトマスクの最小未露光部の直径１００μm に対して１０３μm と優れたものであった。
【００４１】
得られた両面フレキシブルプリント配線板を２６０℃の半田浴に浸漬したところ、ふくれ、はがれ等の異常は何ら認められなかった。また、１８０度の折曲げを行っても、クラックの発生は認められなかった。
【００４２】
実施例６
合成例１で得られたオリゴマー溶液５０重量部に、臭素化フェノールノボラック型エポキシ樹脂（日本化薬株式会社製、Ｂｒｅｎ−Ｓ）１８．５重量部、トリプロピレングリコールジアクリレート５重量部及び光重合開始剤１重量部を添加し、１時間撹拌して均一な組成物を得た。ついで、この組成物をアプリケーターを用いて、表面に離型処理を施した厚み５０μm のポリエチレンテレフタレート（ＰＥＴ）フィルムに塗布し、６０℃で３０分間乾燥して、実質的にタックのない厚み５０μm の感光性フィルムを作製した。
【００４３】
この感光性フィルムを回路形成を施したガラスエポキシ片面銅張板（松下電工株式会社製、Ｒ１７００、銅箔１８μm ／ガラスエポキシ３００μm ）上に実施例１で用いたホットラミネーター装置を使ってラミネートした。次に、実施例１で用いた露光機を使い、最小未露光部が直径７０μm となるフォトマスクを通して感光性フィルムを３００ｍＪの露光量で露光した。その後、ＰＥＴフィルムを剥離し、５％炭酸ナトリウム水溶液を用いて４０℃で１分間の現像処理を行った後、純水で洗浄し、２００℃で１５分間熱処理を行って絶縁層を形成した。得られた絶縁層の開口部の精度は、フォトマスクの最小未露光部の直径７０μm に対して７２μm と優れたものであった。
【００４４】
ついで、無電解めっき法により、感光性フィルムより得られた絶縁層上に厚み１８μm の２層目の回路を形成した。その際、絶縁層の開口部を介して１層目と２層目の回路間の導通をとった。
【００４５】
さらに、感光性フィルムのラミネート、露光、現像、熱処理による絶縁層の形成と、めっきによる回路形成を２度繰り返して、合計で回路層が４層の逐次多層基板とした後、感光性フィルムを用いて表面の保護層を形成した。得られた逐次多層基板の各絶縁層の回路間への充填性は良好であった。また、耐半田試験においても異常の発生は認められなかった。
【００４６】
比較例１
合成例５で合成された化合物溶液５０重量部に光重合開始剤１重量部を添加して組成物を得た。この組成物をアプリケーターを用いて、表面に離型処理を施した厚み５０μm のポリエチレンテレフタレート（ＰＥＴ）フィルムに塗布し、６０℃で３０分間乾燥して、実質的にタックのない厚み５０μm のフィルムを作製した。ついで、このフィルムを実施例１で用いた回路形成のなされた片面銅張板上にＰＥＴフィルムを貼り合わせたまま、実施例１で用いたホットラミネーター装置でラミネートした。その際、フィルムは回路間にも空隙なく充填された。
【００４７】
次に、実施例１で用いた露光機を使って、最小未露光部が直径１００μm となるフォトマスクを通して感光性フィルムを３００ｍＪの露光量となるように露光した。その後、ＰＥＴフィルムを剥離し、５％炭酸ナトリウム水溶液を用いて４０℃で１分間の現像処理を行った。しかしながら、ここで用いた化合物は酸無水物との反応を行っていないため、炭酸ナトリウム水溶液による現像処理を行っても、パターンを発現させることはできなかった。
【００４８】
比較例２
実施例２で用いた組成物を、溶液のまま直接実施例１で用いた回路形成が施された片面銅張板上にスピンコート法で塗布し、６０℃で３０分間乾燥して感光性組成物の層を形成した。この際、回路形成された銅張板上に直接塗布したため、塗りむらが確認された。以下、実施例２と同様に、露光、現像及び熱処理を行って、フレキシブルプリント配線板を得た。得られたフレキシブルプリント配線板の耐半田性や耐折曲げ性は良好であったが、反りが大きく、実用に耐えるものではなかった。
【００４９】
【発明の効果】
本発明の感光性フィルム材料は、アルカリ性の水溶液で精度のよいパターニングが可能で、回路への充填性にも優れており、また、耐熱性や機械的特性にも優れているため、フレキシブルプリント配線板のカバーレイや逐次多層基板の絶縁材料等の工業用材料に極めて有用である。
また、本発明の感光性フィルム材料をカバーレイ材又は層間絶縁材料として使用するフレキシブルプリント配線板又は逐次多層基板は、耐熱性が良好で半田浴への浸漬に対しても何ら異常を示さず、また、耐折曲げ性等の機械的特性も優れたものである。[0001]
[Industrial application fields]
The present invention relates to a photosensitive film material suitable for a cover lay of a flexible printed wiring board, an insulating material for a sequential multilayer substrate, and the like, a flexible printed wiring board or a sequential multilayer substrate formed by using this as a cover lay material or an interlayer insulating material, and The present invention relates to these manufacturing methods.
[0002]
[Prior art]
In recent years, electronic devices, computers, and the like have been required to be further miniaturized and highly functional as compared to conventional ones, and parts used in accordance therewith are required to have higher density. For example, in the printed wiring board, in order to improve the wiring density per unit volume, the circuit is miniaturized and multi-layered, and the materials used are also designed according to that. In particular, in recent years, many resist materials having photosensitivity have been proposed. Among them, it is an exaggeration to say that the photo-sensitive etching resist used for forming the conductor circuit supports the circuit miniaturization technology. Absent.
[0003]
However, most of the photosensitive resins that have been proposed so far have problems in heat resistance, mechanical properties, etc., and the disadvantage is that their use is greatly limited like the etching resist that is finally removed. have. Also, except for etching resists called so-called dry films, most of them are supplied in the form of a resin solution in which a photosensitive resin is dissolved in an organic solvent. In order to apply on a plate or the like, there is a problem that a very special device is required. Further, in many cases, the developer used in the developing process, which is a patterning process of the photosensitive resin, is an organic solvent, and has a problem in the working environment and waste liquid treatment.
[0004]
For example, JP-A-6-268380 discloses a printed wiring board using a photosensitive resin, but the photosensitive resin used therein is used in the form of a resin solution. When applying, a special apparatus is required, and the developer used for development is organic, which causes problems in the working environment.
[0005]
In order to solve these problems, JP-A-6-148877 discloses a photosensitive element made of rubber, a phenol resin, an epoxy resin, an epoxy resin photocuring agent, and the like that can form a film. However, when such a composition is used, the heat resistance of the finally obtained film is insufficient, the application to which it is applied is greatly limited, and the accuracy in patterning is also sufficient. hard.
[0006]
JP-A-5-339356 discloses a photosensitive resin composition using a photopolymerizable unsaturated compound having a carboxyl group based on an epoxy acrylate compound together with an epoxy compound. However, the photosensitive resin composition is premised on coating directly on a color liquid crystal display or a printed wiring board using a roll coater or spinner in a solution state. Problems on the equipment.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a photosensitive film material which is suitable for a cover lay of a flexible printed wiring board, an insulating material for a sequential multilayer substrate, and the like and can be patterned with an alkaline aqueous solution.
Another object of the present invention is to provide a flexible printed wiring board or a sequential multilayer board using a photosensitive film material that can be patterned with an alkaline aqueous solution as a coverlay material or an interlayer insulating material, and a method for producing these. There is.
[0008]
[Means for solving the problems]
That is, the present invention contains, as essential components, an oligomer obtained by reacting an epoxy acrylate compound represented by the following general formula (1) and an acid anhydride, and a compound having an epoxy group, and the oligomer and the epoxy group. A flexible printed wiring board using a photosensitive film material for circuit board insulation formed from a composition having a weight ratio of 0.1 to 10 as a coverlay material, and the production thereof Is the method.
[0009]
[Chemical formula 2]

[0010]
(Wherein X represents a divalent group or absence, n represents a number of 1 to 10. R _{1 to} R ₈ represent a hydrogen atom, an alkyl group, or a halogen atom, and each is the same or different. And R ₉ represents a hydrogen atom or a methyl group.)
[0011]
Examples of X in the formula (1) include a divalent group such as a methylene group, a 2-propylidene group, a 2- (hexafluoro) propylidene group, a carbonyl group, an ether group, and a sulfone group, or a direct bond. A 2-propylidene group or a direct bond is preferable. Examples of R _{1 to} R ₈ include a hydrogen atom, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, and an isopropyl group, for example, a halogen atom such as chlorine and bromine. Bromine. n represents an average number of repetitions, and is a number of 1 to 10, preferably 1 to 2.
[0012]
In particular, by using a bisphenol A type epoxy acrylate compound in which X is a 2-propylidene group as a part or all of the epoxy acrylate compound, the photosensitive film material of the present invention is subjected to processing such as patterning and subsequent thermosetting. Thus, the heat resistance and mechanical properties of the finally obtained film can be improved.
[0013]
Examples of the acid anhydride used in the production of the oligomer of the present invention include dicarboxylic anhydrides such as phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride, and examples thereof include pyromellitic anhydride and biphenyltetra Tetracarboxylic dianhydrides such as carboxylic dianhydrides, benzophenone tetracarboxylic dianhydrides, diphenyl sulfone tetracarboxylic dianhydrides, diphenyl ether tetracarboxylic dianhydrides, ethylene glycol bistrimellitic dianhydrides, and more And trimellitic anhydride. In addition, these acid anhydrides may be used alone or in combination of two or more kinds of acid anhydrides. Preferably, ethylene glycol bistrimellitic dianhydride is used in whole or in part as an acid anhydride, whereby mechanical properties such as flexibility of the finally obtained film are improved.
[0014]
The oligomer which is one of the essential components of this invention can be manufactured by making said epoxy acrylate compound and said acid anhydride react. The weight average molecular weight of the oligomer of the present invention is from 500 to 1,000,000, preferably from 700 to 500,000, more preferably from 1,000 to 100,000. If the weight average molecular weight is less than 500, the mechanical properties of the finally obtained film are deteriorated, and if it is more than 1,000,000, it is difficult to form a pattern with an aqueous alkali solution.
[0015]
The photosensitive film material of the present invention contains a compound having an epoxy group as an essential component in addition to the oligomer. Examples of the compound having an epoxy group herein include those having an epoxy group such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol novolac type epoxy resin, an orthocresol novolac type epoxy resin, and brominated compounds thereof. Any can be used as long as it is present. And the flame retardance can be provided to the photosensitive film material of this invention by using the compound which has the brominated epoxy group for a part or all of the compound which has this epoxy group.
[0016]
In the present invention, the weight ratio between the oligomer and the compound having an epoxy group, that is, the ratio of the oligomer / the compound having an epoxy group is 0.1 to 10, preferably 0.2 to 5. If this ratio is less than 0.1, it is difficult to perform patterning with an alkaline aqueous solution, and if it exceeds 10, heat resistance and chemical resistance are lowered.
[0017]
Subsequently, the photosensitive film material of the present invention can be completed by forming a composition containing the oligomer and epoxy as essential components into a film. As used herein, the film form means not only a single film but also a film formed on a support substrate that is finally removed by an operation such as peeling, such as a polymer film or a metal foil. It does not include films or coatings that are permanently formed on the substrate. In addition, the photosensitive film material of the present invention formed on a supporting substrate can be protected with a polymer film or the like in order to prevent adhesion of foreign matters, generation of scratches, and the like.
[0018]
Further, in order to impart various characteristics to the photosensitive film material of the present invention, as other components, amines, photopolymerization initiators, photosensitizers, monomers such as polyfunctional acrylates, plating catalysts, indium and It is also possible to add a tin co-oxide or a filler such as silica in advance. Furthermore, in order to improve the fluidity | liquidity of the photosensitive film before pattern formation, it is also possible to contain a solvent.
[0019]
The method for forming the composition into a film may be a known method. For example, the above composition is dissolved or dispersed in a solvent, applied onto a supporting substrate using any coating device such as a die coater, knife coater, reverse roll coater, and the solvent is evaporated to form a film. Can be formed. As the support substrate, a polymer film such as polyethylene terephthalate or a metal foil can be used. Moreover, it is also possible to make a multilayer photosensitive film material of two or more layers by using two or more kinds of compositions having different configurations as required.
[0020]
The photosensitive film material of the present invention thus obtained can be patterned with a highly accurate alkaline aqueous solution, and also has heat resistance and mechanical properties. Can be used for
[0021]
A suitable use of the photosensitive film material of the present invention is a coverlay for a flexible printed wiring board. In other words, the photosensitive film material of the present invention can form an insulating layer called a coverlay for the purpose of circuit protection on a flexible printed wiring board by a simple operation of laminating. This is because it has sufficient heat resistance to the process such as attaching and excellent bending resistance.
[0022]
The flexible printed wiring board which uses the photosensitive film material for circuit board insulation of this invention as a coverlay can be manufactured through the essential process shown below.
(1) A step of forming a circuit on the metal-clad laminate for a flexible printed wiring board,
(2) A step of laminating the photosensitive film material of the present invention on a metal-clad laminate for a flexible printed wiring board on which a circuit is formed,
(3) performing an exposure and development treatment with an alkaline aqueous solution to form an opening in the laminated photosensitive film material;
(4) The process of performing the heat processing for 1 minute or more at the temperature of 100-300 degreeC.
[0023]
In addition to the essential steps described above, it is of course possible to carry out cleaning, drying, drilling or plating as required. Moreover, as a metal-clad laminate for flexible printed wiring boards, it can be applied to both single-sided metal-clad laminates and double-sided metal-clad laminates.
[0024]
Another preferred application of the photosensitive film material of the present invention is a so-called build-up substrate, which is obtained by repeating the formation of an insulating layer on a conductor circuit and the formation of a new conductor circuit layer by sputtering or plating. Insulating material between the conductors of the sequential multilayer substrate called. This is because the photosensitive film material of the present invention has resistance to sputtering and plating processes in addition to the heat resistance and mechanical characteristics.
[0025]
The sequential multilayer board | substrate which uses the photosensitive film material for circuit board insulation of this invention as an insulating material can be manufactured through the essential process shown below.
(1) a step of producing a material in which a conductor circuit is formed on an insulating substrate;
(2) Laminating the photosensitive film material of the present invention on the material on which the conductor circuit is formed,
(3) performing an exposure and development treatment with an alkaline aqueous solution to form an opening in the laminated photosensitive film material;
(4) performing a heat treatment for 1 minute or more at a temperature of 100 to 300 ° C. to cure the developed film material;
(5) A step of forming the next conductor circuit layer on the cured film by plating, sputtering, vapor deposition, or a combination thereof.
[0026]
The material in which the conductor circuit is formed on the insulating base material used here can be prepared by an etching method using a single-sided or double-sided metal-clad laminate as a starting material, and a glass cloth / polymer composite material or polymer It is also possible to form a conductor circuit directly on one or both sides of the film by a method such as plating, sputtering, or vapor deposition. Moreover, it is possible to manufacture the sequential multilayer substrate in which the conductor layer of 3 layers or more was formed by repeating the process of (2)-(5) among the said processes.
[0027]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to this.
[0028]
Synthesis example 1
As a bisphenol A type epoxy resin (Etototo YD-8125, epoxy equivalent 172 g / eq, manufactured by Toto Kasei Co., Ltd.) 34.0 parts by weight, acrylic acid 14.4 parts by weight, tetraethylammonium bromide 0.05 parts by weight and a solvent 5.85 parts by weight of ethyl cellosolve acetate was charged into a flask and stirred to obtain a uniform solution. This solution was reacted at 105 ° C. for 15 hours to obtain an epoxy acrylate compound. Then, 7.6 parts by weight of 1,2,3,6-tetrahydrophthalic anhydride and 20.5 parts by weight of ethylene glycol bistrimellitic dianhydride were added as acid anhydrides to the reaction solution. A viscous oligomer solution was obtained by reacting for a period of time. The obtained oligomer had a weight average molecular weight of 2,500 as determined by GPC analysis.
[0029]
Synthesis example 2
Instead of 7.6 parts by weight of 1,2,3,6-tetrahydrophthalic anhydride and 20.5 parts by weight of ethylene glycol bistrimellitic dianhydride in Synthesis Example 1, 41.0 ethylene glycol bistrimellitate dianhydride Synthesis was performed in the same manner as in Synthesis Example 1 using only parts by weight. The weight average molecular weight of the obtained oligomer was 3,800.
[0030]
Synthesis example 3
Synthesis was carried out in the same manner as in Synthesis Example 1 using 14.7 parts by weight of biphenyltetracarboxylic dianhydride instead of 20.5 parts by weight of ethylene glycol bistrimellitic dianhydride in Synthesis Example 1. The obtained oligomer had a weight average molecular weight of 1,800.
[0031]
Synthesis example 4
Instead of 34.0 parts by weight of the bisphenol A type epoxy resin of Synthesis Example 1 (Etoto Chemical Co., Ltd., Epototo YD-8125), bisphenol A type epoxy resins having different epoxy equivalents (Etoto Chemical Co., Ltd., Epototo YD-128) The epoxy compound was synthesized in the same manner as in Synthesis Example 1 using 38.0 parts by weight of an epoxy equivalent of 192 g / eq, and 7.50 parts by weight of ethyl cellosolve acetate as a solvent. The weight average molecular weight of the obtained oligomer was 6,500.
[0032]
Synthesis example 5
Bisphenol A type epoxy resin (Etoto YD-8125, manufactured by Toto Kasei Co., Ltd.) 34.0 parts by weight, acrylic acid 14.4 parts by weight, tetraethylammonium bromide 0.05 parts by weight, and ethyl cellosolve acetate 5.85 parts by weight Was placed in a flask and stirred to obtain a uniform solution. Subsequently, it was made to react at 105 degreeC for 15 hours, and the epoxy acrylate compound was obtained. The molecular weight of the obtained compound was 484. This compound was not reacted with an acid anhydride.
[0033]
Example 1
50 parts by weight of the oligomer solution obtained in Synthesis Example 1 and 1 part by weight of a photopolymerization initiator (Ciba Geigy Co., Ltd., Irgacure 651) and bisphenol A type epoxy resin (Etoto YD-901, manufactured by Toto Kasei Co., Ltd.) 28.7 A photosensitive composition was obtained by adding parts by weight. This composition is applied onto a 50 μm thick polyethylene terephthalate (PET) film having a release treatment applied to the surface using an applicator, dried at 60 ° C. for 30 minutes, and has a thickness of 50 μm with substantially no tack. A conductive film was prepared. Subsequently, this photosensitive film was formed into a single-sided copper-clad laminate (Espanex SC35-40-00ME (electrolytic foil 35 μm / polyimide, manufactured by Nippon Steel Chemical Co., Ltd.) with a circuit formed in a shape having a minimum circuit width of 100 μm and a minimum circuit width of 100 μm. 40 μm)) With the PET film stuck on top, the hot laminator device (manufactured by Taisei Laminator Co., Model 8B-550, temperature 80 ° C., feed) so that the photosensitive film and the circuit surface of the single-sided copper-clad laminate are in contact with each other (Speed: 1 m / min). At that time, the photosensitive film was filled with no gaps between the circuits.
[0034]
Next, the photosensitive film was exposed at an exposure amount of 300 mJ through a photomask having a minimum unexposed area of 100 μm in diameter using an exposure machine (HTE-3000NEL, manufactured by Hitec Corporation). Thereafter, the PET film was peeled off, developed with a 5% aqueous sodium carbonate solution at 40 ° C. for 1 minute, washed with pure water, and heat treated at 180 ° C. for 60 minutes to form a pattern. The flexible printed wiring board with which the photosensitive film was comprised as a coverlay was obtained. The pattern accuracy of the coverlay of the obtained flexible printed wiring board was as excellent as 102 μm with respect to the diameter of 100 μm of the smallest unexposed portion of the photomask.
[0035]
When the obtained flexible printed wiring board was immersed in a solder bath at 260 ° C. for 1 minute, abnormalities such as blistering and peeling were not observed. Moreover, even if it bent 180 degree | times with respect to the flexible printed wiring board, generation | occurrence | production of the crack was not recognized.
[0036]
Example 2
Processed in the same manner as in Example 1 except that 50 parts by weight of the oligomer solution obtained in Synthesis Example 2 was used as the oligomer component, and the development processing conditions were changed from 5% sodium carbonate 40 ° C. for 1 minute to 2% sodium carbonate 40 ° C. for 1 minute. did. The filling property of the photosensitive film into the circuit was good, and the pattern accuracy was as excellent as 103 μm. Further, the obtained flexible printed wiring board showed no abnormality even when immersed in a solder bath, and was excellent in bending resistance.
[0037]
Example 3
The same procedure as in Example 1 was performed using 50 parts by weight of the oligomer solution obtained in Synthesis Example 3 as the oligomer component. The filling property of the photosensitive film into the circuit was good, and the pattern accuracy was as excellent as 105 μm. Further, the obtained flexible printed wiring board showed no abnormality even when immersed in a solder bath, and was excellent in bending resistance.
[0038]
Example 4
5 parts by weight of triethylene glycol diacrylate was further added to the composition used in Example 1, and the same treatment as in Example 1 was performed. The filling property of the photosensitive film into the circuit was good, and the pattern accuracy was as excellent as 101 μm. Further, the obtained flexible printed wiring board showed no abnormality even when immersed in a solder bath, and was excellent in bending resistance.
[0039]
Example 5
To 50 parts by weight of the oligomer solution obtained in Synthesis Example 4, 26.5 parts by weight of brominated bisphenol A type epoxy resin (manufactured by Toto Kasei Co., Ltd., Epototo YDB-400), photopolymerization initiator (manufactured by Ciba Geigy Co., Ltd., Irgacure) 651) 1 part by weight and 5 parts by weight of triethylene glycol diacrylate were added and stirred for 1 hour to obtain a uniform composition. Next, this composition was applied to a polyethylene terephthalate (PET) film having a thickness of 50 μm with a release treatment using an applicator, dried at 80 ° C. for 5 minutes, and a thickness of 40 μm having substantially no tack. A photosensitive film was prepared. Separately, a double-sided copper-clad laminate (manufactured by Nippon Steel Chemical Co., Ltd., Espanex SB35-50-35HR (copper foil 35 μm / polyimide 50 μm)) has a minimum circuit width of 100 μm and a circuit between the minimum circuits of 100 μm. Formation was performed. The photosensitive film was laminated on both sides of the double-sided copper-clad board on which this circuit was formed using the hot laminator apparatus used in Example 1. At that time, the filling property between the circuits was good.
[0040]
Next, using the exposure machine used in Example 1, the photosensitive films on both sides were exposed with an exposure amount of 250 mJ through a photomask having a minimum unexposed area of 100 μm in diameter. Thereafter, the PET film was peeled off, developed with a 5% aqueous sodium carbonate solution at 40 ° C. for 1 minute, washed with pure water, and heat treated at 200 ° C. for 30 minutes to form a pattern. A double-sided flexible printed wiring board in which the photosensitive film was configured as a coverlay was obtained. The pattern accuracy of the coverlay of the obtained flexible printed wiring board was excellent at 103 μm with respect to the diameter of 100 μm of the minimum unexposed portion of the photomask.
[0041]
When the obtained double-sided flexible printed wiring board was immersed in a solder bath at 260 ° C., no abnormality such as blistering or peeling was observed. In addition, no cracks were observed even when bending at 180 degrees.
[0042]
Example 6
50 parts by weight of the oligomer solution obtained in Synthesis Example 1, 18.5 parts by weight of brominated phenol novolac type epoxy resin (Nippon Kayaku Co., Ltd., Bren-S), 5 parts by weight of tripropylene glycol diacrylate and photopolymerization 1 part by weight of an initiator was added and stirred for 1 hour to obtain a uniform composition. Next, this composition was applied to a polyethylene terephthalate (PET) film having a thickness of 50 μm with a release treatment using an applicator, dried at 60 ° C. for 30 minutes, and a thickness of 50 μm having substantially no tack. A photosensitive film was prepared.
[0043]
This photosensitive film was laminated on a glass epoxy single-sided copper-clad plate (M1 manufactured by Matsushita Electric Works, Ltd., R1700, copper foil 18 μm / glass epoxy 300 μm) using the hot laminator apparatus used in Example 1. Next, using the exposure machine used in Example 1, the photosensitive film was exposed at an exposure amount of 300 mJ through a photomask having a minimum unexposed area of 70 μm in diameter. Thereafter, the PET film was peeled off, developed with a 5% aqueous sodium carbonate solution at 40 ° C. for 1 minute, washed with pure water, and heat treated at 200 ° C. for 15 minutes to form an insulating layer. The accuracy of the opening of the obtained insulating layer was as excellent as 72 μm with respect to the diameter 70 μm of the smallest unexposed portion of the photomask.
[0044]
Then, a second layer circuit having a thickness of 18 μm was formed on the insulating layer obtained from the photosensitive film by an electroless plating method. At that time, electrical conduction was established between the circuits of the first layer and the second layer through the opening of the insulating layer.
[0045]
Furthermore, the formation of an insulating layer by photosensitive film lamination, exposure, development, and heat treatment, and circuit formation by plating were repeated twice to form a sequential multilayer substrate having a total of four circuit layers, and then the photosensitive film was used. Thus, a protective layer was formed on the surface. The filling property between the circuits of each insulating layer of the obtained sequential multilayer substrate was good. In addition, no abnormality was observed in the solder resistance test.
[0046]
Comparative Example 1
A composition was obtained by adding 1 part by weight of a photopolymerization initiator to 50 parts by weight of the compound solution synthesized in Synthesis Example 5. Using an applicator, this composition was applied to a 50 μm-thick polyethylene terephthalate (PET) film whose surface had been subjected to a release treatment, and dried at 60 ° C. for 30 minutes. Produced. Next, this film was laminated with the hot laminator apparatus used in Example 1 while the PET film was bonded to the single-sided copper-clad board on which the circuit was formed used in Example 1. At that time, the film was filled with no gap between the circuits.
[0047]
Next, using the exposure machine used in Example 1, the photosensitive film was exposed to a 300 mJ exposure amount through a photomask having a minimum unexposed area of 100 μm in diameter. Thereafter, the PET film was peeled off, and development processing was performed at 40 ° C. for 1 minute using a 5% aqueous sodium carbonate solution. However, since the compound used here did not react with an acid anhydride, it was not possible to develop a pattern even when a development treatment with an aqueous sodium carbonate solution was performed.
[0048]
Comparative Example 2
The composition used in Example 2 was directly applied as a solution on a single-sided copper-clad board on which the circuit formation used in Example 1 had been applied, by spin coating, and dried at 60 ° C. for 30 minutes to form a photosensitive composition. A layer of material was formed. At this time, since the coating was directly applied on the copper-clad plate on which the circuit was formed, coating unevenness was confirmed. Thereafter, exposure, development and heat treatment were performed in the same manner as in Example 2 to obtain a flexible printed wiring board. Although the obtained flexible printed wiring board had good solder resistance and bending resistance, the warp was large and it was not practical.
[0049]
【The invention's effect】
The photosensitive film material of the present invention can be patterned accurately with an alkaline aqueous solution, has excellent circuit filling properties, and is excellent in heat resistance and mechanical properties. It is extremely useful for industrial materials such as cover lays for plates and insulating materials for sequential multilayer substrates.
Moreover, the flexible printed wiring board or sequential multilayer board using the photosensitive film material of the present invention as a coverlay material or an interlayer insulating material has good heat resistance and does not show any abnormality even when immersed in a solder bath, In addition, mechanical properties such as bending resistance are excellent.

Claims (5)

Weight of the oligomer obtained by reacting the epoxy acrylate compound represented by the following general formula (1) with an acid anhydride and a compound having an epoxy group as essential components, and the weight of the oligomer and the compound having an epoxy group A flexible printed wiring board comprising: a cover film material made of a photosensitive film material for circuit board insulation formed from a composition having a ratio in the range of 0.1 to 10 .

(Wherein X represents a divalent group or absence, n represents a number of 1 to 10. R _{1 to} R ₈ represent a hydrogen atom, an alkyl group, or a halogen atom, and each is the same or different. R ₉ represents a hydrogen atom or a methyl group) The flexible printed wiring board according to claim 1, wherein a part or all of the epoxy acrylate compound is a compound in which X in the general formula (1) is a 2-propylidene group . The flexible printed wiring board according to claim 1 or 2, wherein a part or all of the compound having an epoxy group is a compound containing a bromine atom . The flexible printed wiring board according to any one of claims 1 to 3, wherein a part or all of the acid anhydride is ethylene glycol bistrimellitate dianhydride . The manufacturing method of the flexible printed wiring board characterized by making the following processes into an essential process.
(1) A step of forming a circuit on a metal-clad laminate for a flexible printed wiring board,
(2) A step of laminating a photosensitive film material for circuit board insulation used as a coverlay material in claim 1 on a metal-clad laminate for a flexible printed wiring board on which a circuit is formed,
(3) A step of forming an opening in the laminated photosensitive film material by performing exposure and development with an alkaline aqueous solution,
(4) The process of performing the heat processing for 1 minute or more at the temperature of 100-300 degreeC.