JP2004186166A - Board for printed circuit and printed circuit board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a board for a plating-type printed circuit, which is high in initial adhesion to a plating layer formed on a heat-resistant film, kept high in adhesion and superior in durability under the conditions of high temperatures and humidity when it is left to stand for a long term after it is subjected to thermal loading. <P>SOLUTION: A heat-resistant resin layer and a conductive metal layer are successively laminated on, at least, one of the surfaces of the heat-resistant insulating film for the formation of the board used for a printed circuit. The heat-resistant resin is a polyimide resin composed of an aromatic tetracarboxylic acid component and a diamine component, the polyimide resin is obtained by polymerizing a tetracarboxylic acid component that contains 60 mol% or more aromatic tetracarboxylic acid and a diamine component that contains 5 to 50 mol% siloxane diamine and 0.1 to 40 mol% diamine having an aromatic ring, and the board is characterized by the fact that the conductive metal layer contains the plating layer. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００２４】
（ただし、一般式（１）〜（３）のｎはいずれも０〜４の整数を示す。）
【００２５】
【化５】

【００２６】
（ただし、一般式（４）のｎは１〜３０の整数を示す。また、Ｒ^１およびＲ^２は、それぞれ同一または異なっていてよく、低級アルキレン基またはフェニレン基を示す。Ｒ^３〜Ｒ^６は、それぞれ同一または異なっていてよく、低級アルキル基、フェニル基またはフェノキシ基を示す。）
【００２７】
【発明の実施の形態】
本発明のプリント回路用基板は、耐熱性絶縁フィルムの少なくとも片面に耐熱性樹脂層、及び、導電性金属層を有し、３つの層がこの順に積層されてなるプリント回路用基板である。従って発明の効果を妨げない限り、耐熱性絶縁フィルムと耐熱性樹脂層の間や、耐熱性樹脂層と導電性金属層の間に前記３つの層以外の層が挿入されていても良く、それが１層または複数層であってもよい。また、耐熱性絶縁フィルム、耐熱性樹脂層または導電性金属層の少なくともいずれかの層が複数の層よりなるものであっても良い。
【００２８】
なお、プリント回路とは、金属層が形成された電気回路のことである。回路のピッチは特に限定されないが、好ましくは１０〜１５０μｍ、より好ましくは１５〜１００μｍ、さらに好ましくは２０〜８０μｍの範囲である。
【００２９】
本発明において使用される耐熱性絶縁フィルムは、絶縁性を有するフィルムである必要がある。耐熱性のレベルとしては、融点が２８０℃以上、好ましくは３００℃以上、より好ましくは３５０℃以上のもの、あるいはＪＩＳ Ｃ４００３で規定される長時間連続使用の最高許容温度が１２１℃以上、好ましくは１５０℃以上、より好ましくは２００℃以上のもののいずれかでの条件を満足すればよい。前記数値範囲の下限値を下回ると長期耐熱信頼性が劣るため好ましくない。
【００３０】
本発明における耐熱性絶縁フィルムとしては上記した条件を満たせば素材は特に限定されないが、好ましくは耐熱性高分子が使用される。具体的には、例えば、芳香族ポリイミド系樹脂、ポリフェニレンサルファイド系樹脂、芳香族ポリアミド系樹脂、ポリアミドイミド系樹脂、芳香族ポリエステル系樹脂などであり、具体的な製品としては、東レ・デュポン（株）製“カプトン”、宇部興産（株）製“ユーピレックス”、鐘淵化学工業（株）製“アピカル”、東レ（株）製“ミクトロン”、（株）クラレ製“ベクスター”などが挙げられる。これらの中でも、芳香族ポリイミド系樹脂が特に好ましく用いられる。
【００３１】
耐熱性絶縁フィルムの厚みは特に限定されないが、好ましくは３〜１５０μｍ、より好ましくは５μｍ〜７５μｍ、特に好ましくは１０μｍ〜５０μｍである。３μｍを下回ると支持体としての強度が不足することがある。一方、１５０μｍを上回ると柔軟性が低下し、折り曲げが困難となる場合があるからである。
【００３２】
本発明に使用する耐熱性絶縁フィルムの片面あるいは両面は、目的に応じ、放電処理などの接着性改良の処理が施されていることが好ましい。
【００３３】
放電処理としては、大気圧付近で放電するいわゆる常圧プラズマ処理、コロナ放電処理、低温プラズマ処理などが好ましく使用される。これらの処理を施すことによって、耐熱性絶縁フィルムと耐熱性樹脂層との接着性を大幅に向上させることができる。
【００３４】
常圧プラズマ処理とは、Ａｒ、Ｎ_２ 、Ｈｅ、ＣＯ_２ 、ＣＯ、空気、水蒸気などの雰囲気中で放電処理する方法をいう。処理の条件は、処理装置、処理ガスの種類、流量、電源の周波数などによって異なるが、適宜最適条件を選択することができる。
【００３５】
低温プラズマ処理は、減圧下で行なうことができ、その方法としては、特に限定されないが、例えば、ドラム状電極と複数の棒状電極からなる対極電極を有する内部電極型の放電処理装置内に被処理基材をセットし、処理ガスを１〜１０００Ｐａ、好ましくは５〜１００Ｐａに調整した状態で電極間に直流あるいは交流の高電圧を印加して放電を行い、前記処理ガスのプラズマを発生させ、該プラズマに基材表面をさらして処理する方法などが好ましく使用される。低温プラズマ処理の条件としては、処理装置、処理ガスの種類、圧力、電源の周波数などによって異なるが、適宜最適条件を選択することができる。処理ガスの種類としては、例えば、Ａｒ、Ｎ_２ 、Ｈｅ、ＣＯ_２ 、ＣＯ、空気、水蒸気、Ｏ_２、ＣＦ_４ などを単独であるいは混合して用いることができる。
【００３６】
コロナ放電処理も使用できるが、コロナ放電処理を使用する場合は、低温プラズマ処理と比較して接着性向上の効果が小さいことがあるので、積層する耐熱性樹脂層が接着しやすいものを選択することが好ましい。
【００３７】
本発明のプリント回路用基板において、耐熱性樹脂層を構成する耐熱性樹脂はポリイミド系樹脂である。ポリイミド系樹脂とは、その前駆体であるポリアミド酸またはそのエステル化合物を加熱あるいは触媒等により、イミド環や、その他の環状構造を形成したポリマーである。ポリアミド酸またはそのエステル化合物は、例えば、テトラカルボン酸成分とジアミン成分を選択的に組み合わせて得られる。テトラカルボン酸成分としては、例えば、テトラカルボン酸二無水物が挙げられる。
【００３８】
本発明者らは耐熱性樹脂層に用いるポリイミド系樹脂の組成と導電性金属層との接着性を鋭意検討した結果、テトラカルボン酸成分にある特定の骨格を有する芳香族テトラカルボン酸類を用い、ジアミン成分として、ある特定範囲のシロキサン系ジアミンを含有し、さらに芳香族環を１個有するジアミンをある特定範囲で含有させることにより、導電性金属層との初期接着力、熱負荷後の接着力、耐湿熱試験後の接着力において特異的に高い接着性を得ることができることを発見した。
【００３９】
つまり、本発明のポリイミド系樹脂は、テトラカルボン酸成分が一般式（１）〜（３）で表される骨格の少なくとも１つを有する芳香族テトラカルボン酸二無水物を含むことにより、導電性金属層との高い接着性を得ることができる。
【００４０】
【化６】

【００４１】
ただし、一般式（１）〜（３）のｎはいずれも０〜４の整数を示す。
【００４２】
より高い導電性金属層との接着性を得るためには、上記骨格を有する芳香族テトラカルボン酸二無水物の中でも特にビフェニル骨格を有する芳香族テトラカルボン酸二無水物が好ましく、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物がさらに好ましい。
【００４３】
上記骨格を有する芳香族テトラカルボン酸二無水物は、全テトラカルボン酸成分中６０モル％以上、好ましくは８０モル％以上、さらに好ましくは９５モル％以上含有していることが必要である。含有量が６０モル％未満だと導電性金属層と十分な接着性を得ることができない。
【００４４】
本発明においては導電性金属層との接着性を損なわない程度にその他のテトラカルボン酸二無水物を添加することができる。例えば、環状炭化水素を持つ脂環式テトラカルボン酸二無水物、芳香族環又は芳香族複素環を含む芳香族テトラカルボン酸二無水物などが挙げられるが、これらに限定されるものではない。
【００４５】
ここで、脂環式テトラカルボン酸二無水物の具体例としては、２，３，５−トリカルボキシシクロペンチル酢酸二無水物、１，２，３，４−シクロブタンテトラカルボン酸二無水物、１，２，３，４−シクロペンタンテトラカルボン酸二無水物、１，２，３，５−シクロペンタンテトラカルボン酸二無水物、１，２，４，５−ビシクロヘキセンテトラカルボン酸二無水物、１，２，４，５−シクロヘキサンテトラカルボン酸二無水物、１，３，３ａ，４，５，９ｂ−ヘキサヒドロ−５−（テトラヒドロ−２，５−ジオキソ−３−フラニル）−ナフト［１，２−Ｃ］フラン−１，３−ジオンなどが挙げられるが、これらに限定されるものではない。
【００４６】
また、芳香族テトラカルボン酸二無水物の具体例としては、３，３´，４，４´−ベンゾフェノンテトラカルボン酸二無水物、２，２´，３，３´−ベンゾフェノン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´−ジフェニルエーテルテトラカルボン酸二無水物、３，３´，４，４´−ビフェニルトリフルオロプロパ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、３，４，９，１０−ペリ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、１，４，５，８−ナフタレンテトラカルボン酸二無水物、１，２，５，６−ナフタレンテトラカルボン酸二無水物、３，３″，４，４″−パラターフェニルテトラカルボン酸二無水物、３，３″，４，４″−メタターフェニルテトラカルボン酸二無水物、２，３，６，７−アントラセンテトラカルボン酸二無水物、１，２，７，８−フェナントレンテトラカルボン酸二無水物、４，４´−（ヘキサフルオロイソプロピリデン）ジフタル酸無水物などが挙げられるが、これらに限定されるものではない。
【００４７】
耐熱性の点から、テトラカルボン酸成分としては、芳香族テトラカルボン酸二無水物を用いるのが好ましい。
【００４８】
さらに、本発明のポリイミド系樹脂はジアミン成分に少なくとも一般式（４）で表されるシロキサン系ジアミンを５〜５０モル％、好ましくは１０〜４８モル％、さらに好ましくは１５〜４６モル％、芳香族環を１個有するジアミンを０．１〜４０モル％、好ましくは０．５〜３５モル％、さらに好ましくは１〜３０モル％含むことにより、導電性金属層との接着性をさらに向上させることができる。
【００４９】
【化７】

【００５０】
ただし、式中ｎは１〜３０の整数を示す。また、Ｒ^１およびＲ^２は、それぞれ同一または異なっていてよく、低級アルキレン基またはフェニレン基を示す。Ｒ^３〜Ｒ^６は、それぞれ同一または異なっていてよく、低級アルキル基、フェニル基またはフェノキシ基を示す。
【００５１】
シロキサン系ジアミンの含有量が５モル％未満だと導電性金属層との初期接着力が低くなり、５０モル％より大きくなると初期接着力は高いが、耐湿熱試験後の接着力が大きく低下する。
【００５２】
芳香族環を１個有するジアミンは、少量の添加であっても導電性金属層との初期接着力、熱負荷後の接着力が向上するが、含有量が０．１モル％未満だとその接着性向上効果が小さい。しかし、含有量が４０モル％より大きくなると、導電性金属層との初期接着力、熱負荷後の接着力は高いが、耐湿熱試験後の接着力が原因は不明であるが、著しく低下する。
【００５３】
一般式（４）で表されるシロキサン系ジアミンは長鎖のものを用いると反応性が悪くなるため、ポリマーの重合度が低くなり、耐熱性などが悪くなるので好ましくない。一般式（４）中のｎの数は１〜３０、好ましくは１〜１５、さらに好ましくは１〜５である。
【００５４】
一般式（４）で表されるシロキサン系ジアミンの具体例としては、１，１，３，３−テトラメチル−１，３−ビス（４−アミノフェニル）ジシロキサン、１，１，３，３−テトラフェノキシ−１，３−ビス（４−アミノエチル）ジシロキサン、１，１，３，３，５，５−ヘキサメチル−１，５−ビス（４−アミノフェニル）トリシロキサン、１，１，３，３−テトラフェニル−１，３−ビス（２−アミノエチル）ジシロキサン、１，１，３，３−テトラフェニル−１，３−ビス（３−アミノプロピル）ジシロキサン、１，１，５，５−テトラフェニル−３，３−ジメチル−１，５−ビス（３−アミノプロピル）トリシロキサン、１，１，５，５−テトラフェニル−３，３−ジメトキシ−１，５−ビス（４−アミノブチル）トリシロキサン、１，１，５，５−テトラフェニル−３，３−ジメトキシ−１，５−ビス（５−アミノペンチル）トリシロキサン、１，１，３，３−テトラメチル−１，３−ビス（２−アミノエチル）ジシロキサン、１，１，３，３−テトラメチル−１，３−ビス（３−アミノプロピル）ジシロキサン、１，１，３，３−テトラメチル−１，３−ビス（４−アミノブチル）ジシロキサン、１，３−ジメチル−１，３−ジメトキシ−１，３−ビス（４−アミノブチル）ジシロキサン、１，１，５，５−テトラメチル−３，３−ジメトキシ−１，５−ビス（２−アミノエチル）トリシロキサン、１，１，５，５−テトラメチル−３，３−ジメトキシ−１，５−ビス（４−アミノブチル）トリシロキサン、１，１，５，５−テトラメチル−３，３−ジメトキシ−１，５−ビス（５−アミノペンチル）トリシロキサン、１，１，３，３，５，５−ヘキサメチル−１，５−ビス（３−アミノプロピル）トリシロキサン、１，１，３，３，５，５−ヘキサエチル−１，５−ビス（３−アミノプロピル）トリシロキサン、１，１，３，３，５，５−ヘキサプロピル−１，５−ビス（３−アミノプロピル）トリシロキサンなどが挙げられるが、これらに限定されるものではない。上記シロキサン系ジアミンは単独でも良く、２種以上を混合して使用しても良い。
【００５５】
芳香族環を１個有するジアミンの具体例としては、ｐ−フェニレンジアミン、ｍ−フェニレンジアミン、２，５−ジアミノトルエン、２，４−ジアミノトルエン、２，４−ジアミノピリジン、２，６−ジアミノピリジン、３，５−ジアミノ安息香酸、２，６−ジアミノ安息香酸、３，５−ジアミノベンジルアルリレートなどが挙げられるがこれらに限定されるものではない。上記芳香族環を１個有するジアミンは単独でも良く、２種以上を混合して使用しても良い。これら芳香族環を１個有するジアミンの中でも、ｐ−フェニレンジアミンが最も接着性向上効果が大きく、好ましく用いられる。
【００５６】
ジアミン成分にシロキサン系ジアミン、芳香族環を１個有するジアミンを添加した残りのジアミン成分としては特に限定されないが、例えば、脂肪族ジアミン、環状炭化水素を含む脂環式ジアミン、芳香族環又は芳香族複素環を含む芳香族ジアミンなどのジアミンを適宜混合して用いることができる。
【００５７】
ここで、脂環式ジアミンの具体例としては、１，３−ジアミノシクロヘキサン、１，４−ジアミノシクロヘキサン、４，４´−ジアミノ−３，３´−ジメチルジシクロヘキシルメタン、４，４´−ジアミノ−３，３´−ジメチルジシクロヘキシルなどが挙げられるがこれらに限定されるものではない。
【００５８】
芳香族ジアミンの具体例としては、４，４´−ジアミノジフェニルエーテル、３，３´−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、４，４´−ジアミノジフェニルスルホン、３，３´−ジアミノジフェニルメタン、４，４´−ジアミノジフェニルメタン、４，４´−ジアミノジフェニルサルファイド、ｏ−トリジン、３，３´−ジメチル−４，４´−ジアミノジフェニルメタン、４，４´−ビス（４−アミノフェノキシ）ビフェニル、２，２−ビス［４−（４−アミノフェノキシ）フェニル］プロパン、ビス［４−（４−アミノフェノキシ）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］ヘキサフルオロプロパン、ジアミノベンズアニリドなどが挙げられるが、これらに限定されるものではない。耐熱性の点から、芳香族ジアミンを用いるのが好ましい。
【００５９】
好ましくは、ジアミン成分にシロキサン系ジアミン、芳香族環を１個有するジアミンを添加した残りのジアミン成分としては上記芳香族ジアミンの中でも一般式（５）で表されるジアミンが好ましく、４，４´−ジアミノジフェニルエーテルがさらに好ましく用いられる。
【００６０】
【化８】

【００６１】
ただし、式中ＸはＯ、Ｓ、ＳＯ、ＳＯ_２、Ｃ＝Ｏ、ＣＨ_２を表す。
【００６２】
本発明のポリイミド系樹脂の分子量の調節は、テトラカルボン酸成分またはジアミン成分を当モルにする、または、いずれかを過剰にすることにより行うことができる。テトラカルボン酸成分またはジアミン成分のどちらかを過剰とし、ポリマー鎖末端を酸成分またはアミン成分などの末端封止剤で封止することもできる。酸成分の末端封止剤としてはジカルボン酸またはその無水物が好ましく用いられ、アミン成分の末端封止剤としてはモノアミンが好ましく用いられる。このとき、酸成分またはアミン成分の末端封止剤を含めたテトラカルボン酸成分の酸当量とジアミン成分のアミン当量を等モルにすることが好ましい。
【００６３】
テトラカルボン酸成分を過剰あるいはジアミン成分を過剰になるようにモル比を調整した場合は、安息香酸、無水フタル酸、テトラクロロ無水フタル酸、アニリンなどのジカルボン酸またはその無水物、モノアミンを末端封止剤として添加しても良い。
【００６４】
本発明において、ポリイミド系樹脂のテトラカルボン酸成分／ジアミン成分のモル比は、通常１００／１００とするが、樹脂溶液の粘度が高くなりすぎる場合は１００／１００〜９５、あるいは１００〜９５／１００の範囲でテトラカルボン酸成分／ジアミン成分のモルバランスを崩して調整し、樹脂溶液の粘度が塗工性などに問題の出ない範囲に入るようにするのが好ましい。ただし、モルバランスを崩していくと、樹脂の分子量が低下して硬化後の膜の強度が低くなり、導電性金属層との接着力も弱くなる傾向にあるので、導電性金属層との接着力が弱くならない範囲でモル比を調整するのが好ましい。
【００６５】
本発明において、ポリイミド系樹脂の前駆体の一つであるポリアミド酸は公知の方法によって合成される。例えば、テトラカルボン酸成分とジアミン成分を選択的に組み合わせ、上記所定のモル比で、溶媒中で０〜８０℃で反応させることにより合成することができる。
【００６６】
このときポリマー鎖末端を封止するためのモノアミン、ジカルボン酸またはその無水物は、テトラカルボン酸二無水物、ジアミンと同時に仕込んで反応させても良く、また、テトラカルボン酸二無水物、ジアミンを反応させ、重合した後に添加して反応させても良い。
【００６７】
ポリアミド酸合成の溶媒としては、例えば、Ｎ−メチル−２−ピロリドン、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジメチルホルムアミドなどのアミド系極性溶媒、また、β−プロピオラクトン、γ−ブチロラクトン、γ−バレロラクトン、δ−バレロラクトン、γ−カプロラクトン、ε−カプロラクトンなどのラクトン系極性溶媒、他には、メチルセロソルブ、エチルセロソルブ、メチルカルビトール、エチルカルビトールなどを挙げることができる。これらは単独で用いても良いし、２種以上を混合して用いても良い。
【００６８】
ポリアミド酸の濃度としては、通常５〜６０重量％が好ましく、さらに好ましくは１０〜４０重量％である。
【００６９】
本発明において、耐熱性樹脂層に使用する耐熱性樹脂には、本発明の効果を損なわない範囲で、その他の樹脂や充填材を添加することができる。その他の樹脂としては、アクリロニトリル系樹脂、ブタジエン系樹脂、ウレタン系樹脂、ポリエステル系樹脂、ポリアミド系樹脂、ポリアミドイミド系樹脂、エポキシ系樹脂、フェノール系樹脂などの耐熱性高分子樹脂が挙げられる。充填材としては、有機あるいは無機からなる微粒子、フィラーなどが挙げられる。微粒子、フィラーの具体例としては、シリカ、アルミナ、酸化チタン、石英粉、炭酸マグネシウム、炭酸カリウム、硫酸バリウムなどが挙げられる。
【００７０】
本発明の耐熱性樹脂層に用いる耐熱性樹脂のガラス転移温度は１４０〜２４０℃、好ましくは１４５〜２２０℃、さらに好ましくは１５０〜２００℃の範囲にあることが好ましい。ガラス転移温度が２４０℃より高いと導電性金属層との初期接着力が低くなるため、接着性が総じて悪くなり、ガラス転移温度が１４０℃未満だと、耐湿熱試験後の接着力が著しく低下する。
【００７１】
次に、本発明のプリント回路用基板を得る一例を通じて、耐熱性絶縁フィルムと耐熱性樹脂層の積層方法について詳細に説明する。
【００７２】
耐熱性絶縁フィルムとして、低温プラズマ処理あるいはコロナ放電処理などしたポリイミドフィルム上に、耐熱性樹脂層を設けるためにポリアミド酸ワニスを含む樹脂溶液を均一に塗工する。この塗工方法としては、ロールコータ、ナイフコータ、密封コータ、コンマコータ、ドクターブレードフロートコータなどによるものが挙げられる。次に上記のように耐熱性絶縁フィルムに塗工した溶液の溶媒を、通常、６０〜２００℃程度の温度で連続的または断続的に１〜６０分間で加熱除去をする。
【００７３】
耐熱性絶縁フィルムであるポリイミドフィルム上に形成される耐熱性樹脂層の厚みは、好ましくは０．０５〜１０μｍ、より好ましくは０．１〜８μｍ、特に好ましくは０．４〜５μｍであるが、目的に応じ適宜選定することができる。
【００７４】
また、接着性向上のためには、さらに加熱キュアを施した方が好ましい。加熱キュアの条件としては、通常、２００〜３５０℃で１分〜６０分であるが、樹脂の組成、膜厚などによって適宜選択することができる。
【００７５】
本発明における導電性金属層は、導電性に優れた金属より構成されているならば、特に限定されるものではなく、金属種としては、例えば、アルミニウム、銅、パラジウム、ニッケル、クロム、ＳＵＳ、コバルト、金等の金属またはそれらの合金などを挙げることができるが、電気特性に優れる点から、銅が好ましく、銅を主成分としてメッキ層が形成されていることが好ましい。ここで、主成分とは９０重量％以上であることを言う。
【００７６】
導電性金属層は多層になっていてもかまわない。たとえば、耐熱性樹脂層の表面に、金属を蒸着またはスパッタリングなどによって薄く形成し、その上に同種または異種の金属層をメッキで形成するなどである。導電性金属層が多層の場合、最厚層（あるいは、主成分層と言うことがある）は銅を主成分とすることが好ましい。また、導電性金属層全体として、銅を９０重量％以上含むことが好ましい。
【００７７】
導電性金属層は、メッキ層を含むことが必要である。特に銅を使用する場合、膜の特性および厚みの制御が容易な点から銅メッキ層であることが好ましい。
【００７８】
メッキ層は、一般に電子顕微鏡による断面結晶像において、厚さ方向に発達した結晶が観察される。結晶の厚さ方向の長さは、金属層あるいは主成分層の層厚みの、好適には９０％以上より好適には９５％以上である。
【００７９】
メッキ層を形成するための電気メッキ法は特に限定されるものではなく、通常の硫酸銅メッキ法を用いることができる。導電性金属層、特に銅層の場合、厚みは１〜１８μｍの範囲が好ましい。１μｍより薄いとピンホールが発生しやすく、１８μｍより厚いとメッキ銅の厚みコントロールが難しくなる。より好ましくは２〜１２μｍである。
【００８０】
耐熱性樹脂層、導電性金属層の膜厚は、公知の種々の方法で測定することができる。本発明においては、例えば、得られたプリント回路用基板の断面をＳＥＭで観察することによって耐熱性樹脂層、導電性樹脂層の膜厚を測定することができる。また、導電性金属層の場合、例えば、配線パターンをエッチングして導電性金属層が残っている部分とエッチングした部分の膜厚の差から算出することができる。また、耐熱性樹脂層の場合、例えば、プリント回路用基板の導電性金属層をエッチングした部分の膜厚を測定し、既知の耐熱性絶縁フィルムの膜厚を差し引くことにより算出することができる。
【００８１】
本発明における導電性金属層は、耐熱性樹脂層と接する側に通常はニッケル、クロム等よりなる異種成分層を有していることが好ましく、その厚みは好ましくは２ｎｍ〜３０ｎｍである。異種成分層には銅等が含まれていても良いし、厚さ方向に成分濃度勾配を有して分布していても良い。異種成分層を形成した後にさらに銅層を５０ｎｍ以上スパッタまたは蒸着で積層することが好ましい。この場合、異種成分層とスパッタ等で積層した銅層の全体での総厚みは４００ｎｍ以内にすることが好ましい。
【００８２】
なお前記の異種成分層そのものや、異種成分層にスパッタまたは蒸着で積層した主成分（銅等）層（以下、単にスパッタ主成分層という）がある場合を金属基礎層と言う。即ち、金属基礎層とは、異種成分層、または、異種成分層／スパッタ主成分層よりなるものである。本発明ではメッキ層が必須であるため、好ましくはメッキにより主成分層が設けられるが、その場合には、前記金属基礎層が２ｎｍより薄いとピンホールが多発することがある。また、４００ｎｍより厚いと導電性金属層の形成に長時間を要することになる。この金属基礎層の上に電気メッキ法によって厚み１〜１８μｍの銅層を形成することが特に好適である。
【００８３】
本発明においては、スパッタあるいはメッキ後にさらに熱処理を施しても良い。熱処理の条件としては、通常、２００℃〜３５０℃で１０分〜４８時間であるが、樹脂の組成、膜厚などによって適宜選択することができる。このとき上記目標温度まで段階的に上げていっても良い。また、冷却する時も段階的に冷却していっても良い。
【００８４】
また本発明においては、スパッタ前、耐熱性樹脂層表面に常圧プラズマ処理、コロナ放電処理、低温プラズマ処理などの表面改質処理を施すことにより導電性金属層との接着力をさらに高くすることができる。特に低温プラズマ処理を行うのが効果的であり、その方法としては特に限定されないが、例えば、ドラム状電極と複数の棒状電極からなる対極電極を有する内部電極型の放電処理装置内に被処理基材をセットし、処理ガスを１〜１０００Ｐａ、好ましくは５〜１００Ｐａに調整した状態で電極間に直流あるいは交流の高電圧を印加して放電を行い、前記処理ガスのプラズマを発生させ、該プラズマに基材表面をさらして処理する方法などが好ましく使用される。低温プラズマ処理の条件としては、処理装置、処理ガスの種類、圧力、電源の周波数などによって異なるが、適宜最適条件を選択することができる。処理ガスの種類としては、例えば、Ａｒ、Ｎ_２ 、Ｈｅ、ＣＯ_２ 、ＣＯ、空気、水蒸気、Ｏ_２、ＣＦ_４ などを単独であるいは混合して用いることができる。
【００８５】
本発明において、接着力は、導体幅２ｍｍのパターンを使用し、金属箔を９０度の方向に５０ｍｍ／分の速度で引き剥がした時の剥離強度で測定される。
【００８６】
例えば、耐熱性絶縁フィルムに銅層をメッキ法で積層した「２層型メッキ」品は銅層の接着界面が平坦であり、上記の測定方法では、通常５Ｎ／ｃｍ程度の接着強度である。本発明のプリント回路用基板の場合、メッキ法で金属層を形成しているため金属層の接着界面は平坦であるが、例えば、８Ｎ／ｃｍ以上の接着力を得ることが可能である。また、耐熱性接着層が薄いので、耐熱性絶縁フイルムが本来有する特性を損なわない利点も有している。
【００８７】
本発明のプリント回路基板は、上記したプリント回路用基板を使用したものである。具体的には、例えば、プリント回路用基板の導電性金属層上にレジスト層を形成し、レジスト層を露光・現像することにより配線パターンに合った形状にレジストをパターニングし、パターニングしたレジストをエッチングマスクとして導電性金属層をエッチングして配線パターンを形成し、配線パターン形成後にレジストを除去することにより得られるものである。
【００８８】
得られたプリント回路基板の配線パターンの断面は、銅箔をエッチングする際、厚み方向にエッチングされながら、幅方向にもエッチングされていく（サイドエッチング）ため、トップ（銅箔表面）の線幅がボトム（ベースフィルムに接している面）の線幅よりも狭くなったテーパー形状になる傾向がある。銅箔の厚みが厚くなると、サイドエッチングが大きくなる傾向があるため、厚みは前述した範囲が好ましい。例えば、８０μｍピッチ（配線幅４０μｍ、ギャップ４０μｍ）の配線パターンの場合、ボトム線幅４０μｍに対し、トップ線幅が２０μｍ以上であれば、良好なパターン形状で、半導体を実装する際に接合不良が出ない。トップ線幅が２０μｍより小さくなると半導体を実装する際に接合不良が出やすくなる傾向にある。
【００８９】
本発明のプリント回路用基板は耐熱性絶縁フィルムの片面あるいは両面に導電性金属層を有することができる。したがって、セミアディティブ方式あるいはサブトラクティブ方式を用いて配線を形成することにより片面あるいは両面配線板を形成することができる。
【００９０】
【実施例】
以下、本発明を実施例に基づいて詳細に説明するが、本発明はこれらに限定されるものではない。なお、接着性、耐湿熱試験、熱負荷試験、スズメッキ後の熱負荷試験、ガラス転移温度の測定は次の方法で評価および測定を行った。
【００９１】
（１）接着性
金属層を積層後、金属層を塩化第２鉄溶液で２ｍｍ幅にエッチングし、該２ｍｍ幅の金属層を ＴＯＹＯ ＢＯＬＤＷＩＮ社製”テンシロン”ＵＴＭ−４−１００にて引っ張り速度５０ｍｍ／分、９０゜剥離で測定した。
【００９２】
（２）耐湿熱試験
金属層を積層後、金属層を塩化第２鉄溶液で２ｍｍ幅にエッチングし、１２１℃／１００％ＲＨ／２気圧に設定された高温高湿オーブン中に９６時間おいた後取り出し、（１）に記載した通りの接着性を評価した。
【００９３】
（３）熱負荷試験
金属層を積層後、金属層を塩化第２鉄溶液で２ｍｍ幅にエッチングした後、１５０℃に設定された熱風オーブン中に２４０時間おいた後取り出し、（１）に記載した通りの接着性を評価した。
【００９４】
（４）スズメッキ後の熱負荷試験
金属層を積層後、金属層を塩化第２鉄溶液で２ｍｍ幅にエッチングした後、東京応化（株）製のスズメッキ液ＬＴ−３４を用い、液温度７０℃、メッキ時間５分で無電解スズメッキし、水洗・乾燥した。１５０℃に設定された熱風オーブン中に２４０時間おいた後取り出し、（１）に記載した通りの接着性を評価した。
【００９５】
（５）ガラス転移温度の測定
耐熱性樹脂溶液を銅箔の光沢面に塗布し、熱風オーブンで１２０℃×１０分で乾燥した。次にイナートオーブンを用い、窒素雰囲気下２８０℃×１時間で熱硬化した。得られたサンプルを塩化第２鉄エッチング液に浸けて銅箔を全面エッチングした後、流水で洗浄、乾燥し、耐熱性樹脂の単膜を得た。
【００９６】
得られた耐熱性樹脂の単膜約１０ｍｇをアルミ製標準容器に詰め、示差走査熱量計 ＤＳＣ−５０（島津製作所（株）製）を用いて測定し（ＤＳＣ法）、得られたＤＳＣ曲線の変曲点からガラス転移温度を計算した。８０℃×１時間で予備乾燥した後、昇温速度２０℃／分で測定を行った。
【００９７】
製造例１
温度計、乾燥窒素導入口、温水・冷却水による加熱・冷却装置、および攪拌装置を付した反応釜にＮ，Ｎ−ジメチルアセトアミド ２０４８ｇを入れ、窒素気流下でビス（３−アミノプロピル）テトラメチルジシロキサン ９９．４ｇ（０．４ｍｏｌ）、ｐ−フェニレンジアミン ２．２ｇ（０．０２ｍｏｌ）、４，４’−ジアミノジフェニルエーテル１１６．１ｇ（０．５８ｍｏｌ）を溶解させた後、３，３´，４，４´−ビフェニルテトラカルボン酸二無水物２９４．２ｇ（１ｍｏｌ）を加え、３０℃で１時間攪拌後、６０℃で５時間攪拌して反応させたことにより、２０重量％ポリアミド酸樹脂溶液（ＰＡ１）を得た。
【００９８】
ポリアミド酸樹脂溶液ＰＡ１をイミド化した樹脂のガラス転移温度は１８０℃であった。
【００９９】
製造例２〜３６
表１および表２に示したテトラカルボン酸成分、ジアミン成分、溶剤を用いた以外は製造例１と同様の操作を行い、２０重量％ポリアミド酸樹脂溶液（ＰＡ２〜３６）を得た。得られたポリアミド酸樹脂溶液をイミド化した樹脂のガラス転移温度もあわせて表１および表２に示した。
【０１００】
【表１】

【０１０１】
【表２】

【０１０２】
ＯＳｉＤＡ、ＰＳｉＤＡは一般式（６）で表されるシリコンジアミンで、ＯＳｉＤＡはアミン当量２３５のシリコンジアミン。ＰＳｉＤＡはアミン当量６５０の東レ・ダウ・コーニング・シリコーン社製シリコンジアミンＢＹ１６−８５３である。
【０１０３】
【化９】

【０１０４】
ただし、ｎは１〜３０の整数を表す。
【０１０５】
実施例１
製造例１で作成したポリアミド酸樹脂溶液（ＰＡ１）を、あらかじめＡｒ雰囲気中で低温プラズマ処理した２５μｍのポリイミドフィルム（東レ・デュポン（株）製“カプトン”１００ＥＮ）に、乾燥後の膜厚が２μｍになるようにバーコーターで塗工し、１００℃で５分、さらに１３０℃で１０分乾燥した。該塗工品を２９０℃で３０分加熱処理を行い、イミド化および残存溶媒の除去を行った。
【０１０６】
上記作製フィルムの耐熱性樹脂塗工面にスパッタ装置（日電アネルバ（株）製ＳＰＬ−５００）を用いて、Ｎｉ／Ｃｒ（組成比：８０／２０（ｗｔ％））層を厚み８ｎｍ設け、次いでその上に銅層を２００ｎｍの厚さでスパッタにより積層した。スパッタ後、直ちに硫酸銅浴を用い、電流密度２Ａ／ｄｍ^２の条件で銅厚みが８μｍとなるようにメッキをし、プリント回路用基板を得た。接着強度の評価結果を表３に示す。
【０１０７】
実施例２〜２２
耐熱性樹脂層の組成、乾燥後の膜厚を表３のごとく変えた以外は実施例１と同様の操作を行い、プリント回路用基板を得た。接着強度の評価結果を表３に示す。
【０１０８】
比較例１〜１９
耐熱性樹脂層の組成、乾燥後の膜厚を表３のごとく変えた以外は実施例１と同様の操作を行い、プリント回路用基板を得た。接着強度の評価結果を表３に示す。
【０１０９】
【表３】

【０１１０】
実施例２３
製造例２で作成したポリアミド酸樹脂溶液（ＰＡ２）を、あらかじめＡｒ雰囲気中で低温プラズマ処理した２５μｍのポリイミドフィルム（宇部興産（株）製“ユーピレックス”２５Ｓ）に、乾燥後の膜厚が１．５μｍになるようにバーコーターで塗工し、１００℃で５分、さらに１３０℃で１０分乾燥した。該塗工品を２９０℃で３０分加熱処理を行い、イミド化および残存溶媒の除去を行った。
【０１１１】
上記作製フィルムの耐熱性樹脂塗工面にスパッタ装置（日電アネルバ（株）製ＳＰＬ−５００）を用いて、Ｎｉ／Ｃｒ（組成比：８０／２０（ｗｔ％））層を厚み８ｎｍ設け、次いでその上に銅層を２００ｎｍの厚さでスパッタにより積層した。スパッタ後、直ちに硫酸銅浴を用い、電流密度２Ａ／ｄｍ^２の条件で銅厚みが８μｍとなるようにメッキをし、プリント回路用基板を得た。接着強度の評価結果を表４に示す。
【０１１２】
実施例２４〜３０
耐熱性樹脂層の組成、乾燥後の膜厚を表４のように変えた以外は実施例２３と同様の操作を行い、プリント回路用基板を得た。接着強度の評価結果を表４に示す。
【０１１３】
比較例２０〜３２
耐熱性樹脂層の組成、乾燥後の膜厚を表４のように変えた以外は実施例２３と同様の操作を行い、プリント回路用基板を得た。接着強度の評価結果を表４に示す。
【０１１４】
【表４】

【０１１５】
以上の結果から本発明品は、いずれも基材フィルムとメッキ銅との高い初期接着力が得られ、かつ熱負荷試験後、耐湿熱試験後の接着力低下が少なく、さらにスズメッキ後にも接着力低下が少なかった。一方、比較例のプリント回路用基板は、初期接着力が低く、また熱負荷試験後、耐湿熱試験後の接着力低下、さらには、スズメッキ後の接着力低下が大きかった。
【０１１６】
実施例３１
製造例２で作成したポリアミド酸樹脂溶液（ＰＡ２）を、あらかじめＡｒ雰囲気中で低温プラズマ処理した２５μｍのポリイミドフィルム（東レ・デュポン（株）製“カプトン”１００ＥＮ）に、乾燥後の膜厚が２μｍになるようにバーコーターで塗工し、１００℃で５分、さらに１３０℃で１０分乾燥した。該塗工品を２９０℃で３０分加熱処理を行い、イミド化および残存溶媒の除去を行った。
【０１１７】
上記作製フィルムの耐熱性樹脂塗工面にスパッタ装置（日電アネルバ（株）製ＳＰＬ−５００）を用いて、Ｎｉ／Ｃｒ（組成比：８０／２０（ｗｔ％））層を厚み８ｎｍ設け、次いでその上に銅層を２００ｎｍの厚さでスパッタにより積層した。スパッタ後、直ちに硫酸銅浴を用い、電流密度２Ａ／ｄｍ^２の条件で銅厚みが８μｍとなるようにメッキを行った。メッキ後、窒素雰囲気下２６０℃で２時間加熱処理を行い、プリント回路用基板を得た。接着強度の評価結果を表５に示す。
【０１１８】
実施例３２
製造例１４で作成したポリアミド酸樹脂溶液（ＰＡ１４）を、あらかじめＡｒ雰囲気中で低温プラズマ処理した２５μｍのポリイミドフィルム（東レ・デュポン（株）製“カプトン”１００ＥＮ）に、乾燥後の膜厚が２μｍになるようにバーコーターで塗工し、１００℃で５分、さらに１３０℃で１０分乾燥した。該塗工品を２９０℃で３０分加熱処理を行い、イミド化および残存溶媒の除去を行った。
【０１１９】
上記作製フィルムの耐熱性樹脂塗工面にスパッタ装置（日電アネルバ（株）製ＳＰＬ−５００）を用いて、Ｎｉ／Ｃｒ（組成比：８０／２０（ｗｔ％））層を厚み８ｎｍ設け、次いでその上に銅層を２００ｎｍの厚さでスパッタにより積層した。スパッタ後に窒素雰囲気下２６０℃で２時間加熱処理を行った後、硫酸銅浴を用い、電流密度２Ａ／ｄｍ^２の条件で銅厚みが８μｍとなるようにメッキを行い、プリント回路用基板を得た。接着強度の評価結果を表５に示す。
【０１２０】
実施例３３
製造例５で作成したポリアミド酸樹脂溶液（ＰＡ５）を、あらかじめＡｒ雰囲気中で低温プラズマ処理した２５μｍのポリイミドフィルム（東レ・デュポン（株）社製“カプトン”１００ＥＮ）に、乾燥後の膜厚が２μｍになるようにバーコーターで塗工し、１００℃で５分、さらに１３０℃で１０分乾燥した。該塗工品を２９０℃で３０分加熱処理を行い、イミド化および残存溶媒の除去を行った。
【０１２１】
耐熱性樹脂層表面をＡｒ雰囲気中で低温プラズマ処理した後、耐熱性樹脂塗工面にスパッタ装置（日電アネルバ（株）製 ＳＰＬ−５００）を用いて、Ｎｉ／Ｃｒ（組成比：８０／２０（ｗｔ％））層を厚み８ｎｍ設け、次いでその上に銅層を２００ｎｍの厚さでスパッタにより積層した。スパッタ後直ちに硫酸銅浴を用い、電流密度２Ａ／ｄｍ^２の条件で銅厚みが８μｍとなるようにメッキを行い、プリント回路用基板を得た。接着強度の評価結果を表５に示す。
【０１２２】
比較例３３
製造例２０で作成したポリアミド酸樹脂溶液（ＰＡ２０）を用いた以外は実施例３１と同様の操作を行い、プリント回路用基板を得た。接着強度の評価結果を表５に示す。
【０１２３】
比較例３４
製造例２９で作成したポリアミド酸樹脂溶液（ＰＡ２９）を用いた以外は実施例３２と同様の操作を行い、プリント回路用基板を得た。接着強度の評価結果を表５に示す。
【０１２４】
比較例３５
製造例３４で作成したポリアミド酸樹脂溶液（ＰＡ３４）を用いた以外は実施例３３と同様の操作を行い、プリント回路用基板を得た。接着強度の評価結果を表５に示す。
【０１２５】
【表５】

【０１２６】
銅メッキ後または銅スパッタ後に熱処理、あるいはスパッタ前に耐熱性樹脂層表面をプラズマ処理することにより、メッキ銅との高い接着力を得ることができた。また、熱負荷試験後、耐湿熱試験後の接着力低下が少なく、さらにスズメッキ後にも接着力低下が少なかった。
【０１２７】
実施例３４
実施例３で得たプリント回路基板の銅箔上にフォトレジスト膜をリバースコーターで乾燥後の膜厚が４μｍになるように塗布、乾燥後、配線パターンが８０μｍピッチ（配線幅４０μｍ、ギャップ幅４０μｍ）になるようにマスク露光し、アルカリ現像液で配線パターンを形成後、銅箔を第二塩化鉄水溶液でウエットエッチング処理した。残ったフォトレジスト膜を除去して銅配線パターンを形成し、プリント回路基板を得た。
【０１２８】
上記方法で得られたプリント回路基板の配線パターンを顕微鏡で観察し、銅配線のボトムとトップの線幅を測定したところ、ボトムの線幅が３９μｍ、トップの線幅が３２μｍで、良好な配線パターンを得ることができた。
【０１２９】
比較例３６（３層型ラミネート品）
ヘンケルジャパン（株）製のポリアミド樹脂 ”マクロメルト”６０３０ ２５０ｇ（５０重量）、油化シェルエポキシ（株）製のエポキシ樹脂 ”エピコート”８２８ １０５ｇ（２１重量％）、昭和高分子（株）製のフェノール樹脂 ＣＫＭ−１６３６ １４５ｇ（２９重量％）をイソプロピルアルコール ６８０ｇとクロロベンゼン １７６０ｇに溶かし、１７重量％のポリアミド／エポキシ／フェノール系接着剤溶液を得た。
【０１３０】
得られたポリアミド／エポキシ／フェノール系接着剤溶液を、あらかじめアルゴン雰囲気中で低温プラズマ処理しておいた厚さ２５μｍのポリイミドフィルム（東レ・デュポン（株）製“カプトン”１００ＥＮ）に、乾燥後の膜厚が６μｍになるようにリバースコーターで塗工し、８０℃で１０分、さらに１３０℃で３０分乾燥した。
【０１３１】
上記作製フィルムの接着剤塗工面に、８０℃で５分予備乾燥後、厚さ１８μｍの電解銅箔を表面温度１４０℃に加熱したロールラミネーターで線圧２ｋｇ／ｃｍ、速度１ｍ／分で張り合わせ、さらに窒素雰囲気下で加熱ステップキュア［（６０℃、３０分）＋（１００℃、１時間）＋（１６０℃、２時間）］を行った後、室温まで徐冷し、プリント回路用基板を得た。
【０１３２】
上記プリント回路用基板を実施例３４と同じ操作を行い、プリント回路基板を得た。上記方法で得られたプリント回路基板の配線パターンを顕微鏡で観察し、銅配線のボトムとトップの線幅を測定したところ、ボトムの線幅が３８μｍ、トップの線幅が１２μｍであり、配線パターンの形状は不良であった。
【０１３３】
比較例３７（２層型キャスト品）
温度計、乾燥窒素導入口、温水・冷却水による加熱・冷却装置、および攪拌装置を付した反応釜にＮ，Ｎ−ジメチルアセトアミド ２０９０ｇを入れ、窒素気流下で４，４’−ジアミノジフェニルエーテル２００．２ｇ（１ｍｏｌ）を溶解させた後、３，３´，４，４´−ベンゾフェノンテトラカルボン酸二無水物 ３２２．２ｇ（１ｍｏｌ）を加え、３０℃で１時間攪拌後、６０℃で５時間攪拌して反応させたことにより、２０重量％のポリアミド酸溶液を得た。
【０１３４】
得られたポリアミド酸溶液を厚さ１８μｍの電解銅箔の凹凸面に、硬化後の膜厚が２５μｍになるようにリバースコーターで塗工し、８０℃で１０分、１４０℃で３０分乾燥した。その後２９０℃で３０分熱硬化させ、プリント回路用基板を得た。
【０１３５】
上記プリント回路用基板を実施例３４と同じ操作を行い、プリント回路基板を得た。上記方法で得られたプリント回路基板の配線パターンを顕微鏡で観察し、銅配線のボトムとトップの線幅を測定したところ、ボトムの線幅が４１μｍ、トップの線幅が１６μｍであり、配線パターンの形状は不良であった。
【０１３６】
【発明の効果】
本発明によれば、耐熱フィルム上に形成した導電性金属層との初期接着力、熱負荷後の接着力、耐湿熱試験後の接着力が総じて高く、さらに、無電解スズメッキを施した後の接着力も高い、接着性に優れるメッキタイプのプリント回路用基板を提供することができ、また、該プリント回路用基板を用いることにより、高密度化された信頼性の高い回路基板を得ることができ、その実用性は多大である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a printed circuit board. In particular, the present invention relates to a high-performance electronic device, and more particularly to a printed circuit board having a high adhesive strength suitable for reduction in size and weight. More specifically, the present invention relates to a printed circuit board used for an FPC (Flexible Printed Circuit), a CSP (Chip Size Package), a BGA (Ball Grid Array), a COF (Chip On Film), or the like in a semiconductor package.
[0002]
[Prior art]
Conventionally, as a substrate for a flexible printed circuit, a "three-layer laminate" product in which a copper foil is bonded to a polyimide resin film via an adhesive has been widely and widely used in various electric devices such as cameras, printers, and personal computers. I have. As the adhesive used for the "three-layer type laminate" product, an epoxy resin type, an acrylic resin type, or the like is used alone or as a mixture. Since these resins contain impurity ions, there is a problem that insulation reliability is reduced. In addition, the heat resistance of the adhesive is inferior to that of polyimide, so that the excellent properties of the polyimide resin film are not fully utilized. Further, when the thickness of the copper foil to be bonded is small, it is difficult to handle the copper foil. Therefore, a copper foil having a thickness of 18 μm or more is generally used, and a copper pattern of 80 μm pitch (wiring width 40 μm, gap 40 μm) or less is required. Is too thick to lower the etching rate, the circuit width on the copper foil surface side and the circuit width on the adhesive surface side are greatly different, or the entire etching is thin, so that fine pitch wiring cannot be obtained. Due to these problems, the "three-layer laminate" product in which copper foil is bonded with an adhesive has a limit in high-density mounting wiring, and is used for high-performance electronic equipment that is small and lightweight. Not suitable for
[0003]
A "two-layer cast" product that forms a heat-resistant insulating layer by coating a resin on a copper foil without using an adhesive can provide good properties in terms of heat resistance and insulation reliability. Also, when the thickness of the copper foil is reduced, it becomes difficult to handle the copper foil. Therefore, a copper foil having a thickness of 18 μm or more is generally used. Therefore, there is a disadvantage that fine pitch wiring cannot be obtained similarly to the "three-layer type laminate" product.
[0004]
As means for obtaining fine pitch wiring, a so-called adhesive-free two-layer type printed circuit board is proposed, in which a conductive metal layer is formed on a polyimide film by a method such as vacuum deposition, sputtering, ion plating, or plating. Have been. The "two-layer plating" products currently on the market, for example, have an adhesion (90-degree peeling strength) between the metal layer and the polyimide of about 6 N / cm. The pattern is less likely to fall off due to the wiring pattern forming process such as the above. However, there is a problem that the adhesion after a heat load test at 150 ° C. for 10 days after the formation of the wiring pattern is reduced to about 2 N / cm or less.
[0005]
Various proposals have been made to improve the characteristics of "two-layer plating" products. There has been proposed a flexible electric circuit carrier having a structure of a chromium-based ceramic vapor deposition layer / copper or copper alloy vapor deposition layer / copper plating layer on a film (for example, see Patent Document 1). However, even with this method, the effect of preventing a decrease in adhesive strength after a heat load test at 150 ° C. for 7 days is insufficient, and the adhesive strength after wiring processing and electroless tin plating is reduced. There is such a problem.
[0006]
A “three-layer plating” product has been proposed in which a metal deposition layer is provided on a film surface via a resin layer, and a thick metal layer is laminated thereon by a plating method (for example, see Patent Document 2). A resin layer using an epoxy resin, an acrylic resin, or the like can improve the adhesive strength to a certain degree, but causes a problem because the heat resistance of the resin layer is reduced. Further, when the modified polyimide resin is used for the resin layer, the heat resistance of the resin is increased, but the adhesiveness is insufficient.
[0007]
There has been proposed a resin using a polyimide-based resin containing aromatic tetracarboxylic dianhydride and siloxane-based diamine as main components as a resin of a "three-layer plating" product in which a resin layer is provided on a film surface (for example, Patent Reference 3). By using a polyimide siloxane-based resin for the resin layer, the initial adhesive strength and the adhesive strength after the heat load test are improved.However, in the proposed technology, since the siloxane component in the polyimide siloxane-based resin is large, the moisture resistance after the wet heat test is improved. There is a problem that the adhesive strength is significantly reduced.
[0008]
As siloxane-based polyimide resins, polyimidesiloxane-based resins using tetracarboxylic acids having a biphenyl skeleton in a tetracarboxylic acid component have been proposed (see, for example, Patent Documents 4 and 5), and these are used as “three-layer type plating” products. Even when used for the resin layer, the initial adhesive strength is improved. However, these also have a problem that the adhesive strength after the moist heat test is significantly reduced because the siloxane component in the polyimide siloxane-based resin is large.
[0009]
A siloxane-based polyimide resin having a relatively low siloxane component using a tetracarboxylic acid having a biphenyl skeleton as a tetracarboxylic acid component has been proposed (for example, see Patent Document 6). When used for, it is possible to reduce the decrease in adhesive strength after moisture and heat resistance, but the initial adhesive strength is low, so the initial adhesive strength, adhesive strength after heat load test, and adhesive strength after wet heat resistance test are generally low. Will be. In addition, there is a problem because the adhesive strength after electroless tin plating is low.
[0010]
4,4'-hexafluoroisopropylidene diphthalic acid and biphenyltetracarboxylic acid are used as the tetracarboxylic acid component, and bis (4-aminophenoxyphenyl) methylene and bis (3-aminopropyl) tetramethyldisiloxane are used as the diamine component. Although the used polyimide siloxane-based resin has been proposed (for example, see Patent Document 7), a high initial adhesive strength, an adhesive strength after a heat load test, and a high adhesive strength after a wet heat resistance test cannot be obtained.
[0011]
The "two-layer plating" product using "UPILEX" manufactured by Ube Industries, Ltd. for the base film adheres to the conductive metal layer more than the case where "Kapton" manufactured by Dupont Toray Co., Ltd. is used for the base film. Poor sex. In order to improve the adhesion, "UPILEX" is used as a base film, and polyimide using pyromellitic dianhydride is formed as an intermediate layer on the film, and a metal vapor deposition layer and a metal plating layer are formed on this. Although a polyimide film with a film has been proposed (for example, see Patent Documents 8 and 9), a sufficiently high initial adhesive force cannot be obtained, and the adhesive force after a heat load test and after a heat and moisture resistance test is significantly reduced.
[0012]
[Patent Document 1]
JP-A-4-329690 (pages 2-3)
[0013]
[Patent Document 2]
JP-A-63-107088 (pages 2-4)
[0014]
[Patent Document 3]
JP-A-2002-264255 (pages 4 to 8)
[0015]
[Patent Document 4]
JP-A-7-258410 (pages 2-4)
[0016]
[Patent Document 5]
JP-A-4-298093 (pages 2-4)
[0017]
[Patent Document 6]
JP-A-1-121325 (pages 2-4)
[0018]
[Patent Document 7]
JP-A-10-317152 (pages 3-5)
[0019]
[Patent Document 8]
JP-A-6-124778 (pages 2-3)
[0020]
[Patent Document 9]
JP-A-6-210794 (page 2-3)
[0021]
[Problems to be solved by the invention]
In view of such a situation, an object of the present invention is to provide an initial adhesive strength with a plating layer formed on a heat-resistant film, an adhesive strength after a heat load, an adhesive strength after a wet heat resistance test, and a high electroless tin plating. An object of the present invention is to provide a plating type printed circuit board which has high adhesion after plating and has excellent adhesion.
[0022]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention has the following configurations. That is, the present invention is a printed circuit board in which a heat-resistant resin layer and a conductive metal layer are sequentially laminated on at least one surface of a heat-resistant insulating film, wherein the heat-resistant resin comprises an aromatic tetracarboxylic acid component and a diamine component. Wherein the polyimide-based resin comprises an aromatic tetracarboxylic acid having at least one of the skeletons represented by the general formulas (1) to (3) in an amount of 60 mol% in the total aromatic tetracarboxylic acid component. The above tetracarboxylic acid component, at least 5 to 50 mol% of the siloxane-based diamine represented by the general formula (4) in the total diamine component, and 0.1 to 0.1% of the diamine having one aromatic ring in the total diamine component. It is a polyimide resin obtained by polymerizing a diamine component containing about 40 mol% and a conductive metal layer including a plating layer.
[0023]
Embedded image

[0024]
(However, n in the general formulas (1) to (3) each represents an integer of 0 to 4.)
[0025]
Embedded image

[0026]
(However, n in the general formula (4) represents an integer of 1 to 30. ¹ And R ² May be the same or different, and represent a lower alkylene group or a phenylene group. R ³ ~ R ⁶ May be the same or different, and represent a lower alkyl group, a phenyl group or a phenoxy group. )
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
The printed circuit board of the present invention is a printed circuit board having a heat-resistant resin layer and a conductive metal layer on at least one surface of a heat-resistant insulating film, and three layers laminated in this order. Therefore, as long as the effects of the invention are not hindered, layers other than the three layers may be inserted between the heat-resistant insulating film and the heat-resistant resin layer, or between the heat-resistant resin layer and the conductive metal layer. May be a single layer or a plurality of layers. Further, at least one of the heat-resistant insulating film, the heat-resistant resin layer and the conductive metal layer may be composed of a plurality of layers.
[0028]
Note that a printed circuit is an electric circuit on which a metal layer is formed. The pitch of the circuit is not particularly limited, but is preferably in the range of 10 to 150 μm, more preferably 15 to 100 μm, and still more preferably 20 to 80 μm.
[0029]
The heat-resistant insulating film used in the present invention needs to be an insulating film. As the heat resistance level, the melting point is 280 ° C. or higher, preferably 300 ° C. or higher, more preferably 350 ° C. or higher, or the maximum allowable temperature for long-term continuous use specified by JIS C4003 is 121 ° C. or higher, preferably What is necessary is just to satisfy | fill the conditions in 150 degreeC or more, More preferably, 200 degreeC or more. Below the lower limit of the above numerical range, the long-term heat resistance is inferior, which is not preferable.
[0030]
The material of the heat-resistant insulating film in the present invention is not particularly limited as long as the above-mentioned conditions are satisfied, but a heat-resistant polymer is preferably used. Specific examples include aromatic polyimide resins, polyphenylene sulfide resins, aromatic polyamide resins, polyamideimide resins, aromatic polyester resins, and the like. Specific products include DuPont Toray Co., Ltd. "Kapton" manufactured by Ube Industries, Ltd., "Upilex" manufactured by Ube Industries, Ltd., "Apical" manufactured by Kanebuchi Chemical Industry Co., Ltd., "Mictron" manufactured by Toray Industries, Inc., "Vexter" manufactured by Kuraray Co., Ltd., and the like. Among these, an aromatic polyimide resin is particularly preferably used.
[0031]
The thickness of the heat-resistant insulating film is not particularly limited, but is preferably 3 to 150 μm, more preferably 5 to 75 μm, and particularly preferably 10 to 50 μm. If it is less than 3 μm, the strength as a support may be insufficient. On the other hand, if it exceeds 150 μm, the flexibility may be reduced and bending may be difficult.
[0032]
It is preferable that one or both surfaces of the heat-resistant insulating film used in the present invention has been subjected to a treatment for improving adhesiveness such as a discharge treatment according to the purpose.
[0033]
As the discharge treatment, a so-called normal-pressure plasma treatment for discharging near the atmospheric pressure, a corona discharge treatment, a low-temperature plasma treatment and the like are preferably used. By performing these treatments, the adhesiveness between the heat-resistant insulating film and the heat-resistant resin layer can be significantly improved.
[0034]
Atmospheric pressure plasma processing refers to Ar, N ₂ , He, CO ₂ , CO, air, steam and the like. The processing conditions vary depending on the processing apparatus, the type of processing gas, the flow rate, the frequency of the power supply, and the like, but the optimum conditions can be appropriately selected.
[0035]
The low-temperature plasma treatment can be performed under reduced pressure, and the method is not particularly limited. For example, the treatment is performed in an internal electrode type discharge treatment apparatus having a drum electrode and a counter electrode composed of a plurality of rod electrodes. The substrate is set, and a processing gas is discharged by applying a high voltage of direct current or alternating current between the electrodes in a state where the processing gas is adjusted to 1 to 1000 Pa, preferably 5 to 100 Pa to generate plasma of the processing gas. A method of exposing the substrate surface to plasma for treatment is preferably used. The conditions for the low-temperature plasma processing vary depending on the processing apparatus, the type of the processing gas, the pressure, the frequency of the power supply, and the like, but the optimum conditions can be appropriately selected. As the type of the processing gas, for example, Ar, N ₂ , He, CO ₂ , CO, air, water vapor, O ₂ , CF ₄ Etc. can be used alone or in combination.
[0036]
Corona discharge treatment can also be used, but when using corona discharge treatment, the effect of improving adhesiveness may be small compared to low-temperature plasma treatment, so select one that the heat-resistant resin layer to be laminated easily adheres to. Is preferred.
[0037]
In the printed circuit board of the present invention, the heat resistant resin constituting the heat resistant resin layer is a polyimide resin. The polyimide-based resin is a polymer in which an imide ring or other cyclic structure is formed by heating or a catalyst or the like of a polyamic acid or its ester compound as a precursor thereof. The polyamic acid or its ester compound is obtained, for example, by selectively combining a tetracarboxylic acid component and a diamine component. Examples of the tetracarboxylic acid component include tetracarboxylic dianhydride.
[0038]
The present inventors have studied the composition of the polyimide resin used for the heat-resistant resin layer and the adhesiveness with the conductive metal layer, and as a result, using an aromatic tetracarboxylic acid having a specific skeleton in the tetracarboxylic acid component, As a diamine component, a specific range of a siloxane-based diamine is further included, and a diamine having one aromatic ring is further included in a specific range, whereby an initial adhesive strength with the conductive metal layer and an adhesive strength after heat load are applied. It has been found that specifically high adhesiveness can be obtained in the adhesive strength after the moist heat test.
[0039]
That is, the polyimide-based resin of the present invention has a conductive property by including an aromatic tetracarboxylic dianhydride having at least one of the skeletons represented by the general formulas (1) to (3). High adhesiveness to the metal layer can be obtained.
[0040]
Embedded image

[0041]
However, n in the general formulas (1) to (3) represents an integer of 0 to 4.
[0042]
In order to obtain higher adhesiveness to the conductive metal layer, among the aromatic tetracarboxylic dianhydrides having the above skeleton, an aromatic tetracarboxylic dianhydride having a biphenyl skeleton is particularly preferable, and 3,3 ′ And 4,4'-biphenyltetracarboxylic dianhydride are more preferred.
[0043]
The aromatic tetracarboxylic dianhydride having the above skeleton needs to be contained in an amount of at least 60 mol%, preferably at least 80 mol%, more preferably at least 95 mol%, of all the tetracarboxylic acid components. If the content is less than 60 mol%, sufficient adhesion to the conductive metal layer cannot be obtained.
[0044]
In the present invention, other tetracarboxylic dianhydrides can be added to such an extent that the adhesion to the conductive metal layer is not impaired. Examples thereof include, but are not limited to, alicyclic tetracarboxylic dianhydride having a cyclic hydrocarbon, and aromatic tetracarboxylic dianhydride containing an aromatic ring or an aromatic heterocyclic ring.
[0045]
Here, specific examples of the alicyclic tetracarboxylic dianhydride include 2,3,5-tricarboxycyclopentylacetic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,5-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-bicyclohexenetetracarboxylic dianhydride, , 2,4,5-cyclohexanetetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2 -C] furan-1,3-dione and the like, but is not limited thereto.
[0046]
Specific examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride and 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride. , Pyromellitic dianhydride, 3,3 ′, 4,4′-diphenylethertetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltrifluoropropanetetracarboxylic dianhydride, 3, 3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1 , 4,5,8-Naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,3 ", 4,4" -p-terphenyltetracarboxylic dianhydride , , 3 ″, 4,4 ″ -methterphenyltetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride , 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride and the like, but are not limited thereto.
[0047]
From the viewpoint of heat resistance, it is preferable to use an aromatic tetracarboxylic dianhydride as the tetracarboxylic acid component.
[0048]
Further, the polyimide resin of the present invention contains at least 5 to 50 mol%, preferably 10 to 48 mol%, more preferably 15 to 46 mol% of a siloxane diamine represented by the general formula (4) as a diamine component. By containing 0.1 to 40 mol%, preferably 0.5 to 35 mol%, more preferably 1 to 30 mol% of a diamine having one aromatic ring, the adhesion to the conductive metal layer is further improved. be able to.
[0049]
Embedded image

[0050]
Here, n represents an integer of 1 to 30. Also, R ¹ And R ² May be the same or different, and represent a lower alkylene group or a phenylene group. R ³ ~ R ⁶ May be the same or different, and represent a lower alkyl group, a phenyl group or a phenoxy group.
[0051]
When the content of the siloxane-based diamine is less than 5 mol%, the initial adhesive strength with the conductive metal layer is low, and when the content is more than 50 mol%, the initial adhesive strength is high, but the adhesive strength after the moist heat test is greatly reduced. .
[0052]
The diamine having one aromatic ring improves the initial adhesive strength to the conductive metal layer and the adhesive strength after heat load even if added in a small amount, but when the content is less than 0.1 mol%, the The effect of improving adhesion is small. However, when the content is more than 40 mol%, the initial adhesive strength to the conductive metal layer and the adhesive strength after heat load are high, but the adhesive strength after the wet heat resistance test is unknown, but the cause is significantly reduced. .
[0053]
If a long-chain siloxane-based diamine represented by the general formula (4) is used, the reactivity is deteriorated, so that the degree of polymerization of the polymer is lowered and the heat resistance is deteriorated. The number of n in the general formula (4) is 1 to 30, preferably 1 to 15, and more preferably 1 to 5.
[0054]
Specific examples of the siloxane-based diamine represented by the general formula (4) include 1,1,3,3-tetramethyl-1,3-bis (4-aminophenyl) disiloxane, 1,1,3,3 -Tetraphenoxy-1,3-bis (4-aminoethyl) disiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis (4-aminophenyl) trisiloxane, 1,1, 3,3-tetraphenyl-1,3-bis (2-aminoethyl) disiloxane, 1,1,3,3-tetraphenyl-1,3-bis (3-aminopropyl) disiloxane, 1,1, 5,5-tetraphenyl-3,3-dimethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis ( 4-aminobutyl) trisiloxane, 1 1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis (5-aminopentyl) trisiloxane, 1,1,3,3-tetramethyl-1,3-bis (2-aminoethyl ) Disiloxane, 1,1,3,3-tetramethyl-1,3-bis (3-aminopropyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis (4-aminobutyl ) Disiloxane, 1,3-dimethyl-1,3-dimethoxy-1,3-bis (4-aminobutyl) disiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5 -Bis (2-aminoethyl) trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis (4-aminobutyl) trisiloxane, 1,1,5,5- Tetramethyl-3,3-dimethoxy-1,5 Bis (5-aminopentyl) trisiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,3,3,5,5- Hexaethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,3,3,5,5-hexapropyl-1,5-bis (3-aminopropyl) trisiloxane and the like, It is not limited to these. The siloxane-based diamines may be used alone or in combination of two or more.
[0055]
Specific examples of the diamine having one aromatic ring include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,4-diaminotoluene, 2,4-diaminopyridine, and 2,6-diamino Examples include, but are not limited to, pyridine, 3,5-diaminobenzoic acid, 2,6-diaminobenzoic acid, 3,5-diaminobenzyl allylate. The diamine having one aromatic ring may be used alone or in combination of two or more. Among these diamines having one aromatic ring, p-phenylenediamine has the greatest effect of improving the adhesiveness and is preferably used.
[0056]
The remaining diamine component obtained by adding a siloxane-based diamine or a diamine having one aromatic ring to the diamine component is not particularly limited. For example, aliphatic diamines, alicyclic diamines containing cyclic hydrocarbons, aromatic rings or aromatic diamines Diamines such as aromatic diamines containing an aromatic heterocyclic ring can be used as appropriate.
[0057]
Here, specific examples of the alicyclic diamine include 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 4,4′-diamino-3,3′-dimethyldicyclohexylmethane, and 4,4′-diamino- Examples include, but are not limited to, 3,3'-dimethyldicyclohexyl.
[0058]
Specific examples of the aromatic diamine include 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, o-tolidine, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoro Propane, diaminobenzanilide, and the like, but are not limited thereto. Not. From the viewpoint of heat resistance, it is preferable to use an aromatic diamine.
[0059]
Preferably, as the remaining diamine component obtained by adding a siloxane-based diamine and a diamine having one aromatic ring to the diamine component, a diamine represented by the general formula (5) is preferable among the above-mentioned aromatic diamines, and 4,4 ′ -Diaminodiphenyl ether is more preferably used.
[0060]
Embedded image

[0061]
Where X is O, S, SO, SO ₂ , C = O, CH ₂ Represents
[0062]
The adjustment of the molecular weight of the polyimide resin of the present invention can be performed by making the tetracarboxylic acid component or the diamine component equimolar, or by making either one excessive. Either the tetracarboxylic acid component or the diamine component may be excessive, and the polymer chain terminal may be sealed with a terminal blocking agent such as an acid component or an amine component. Dicarboxylic acid or its anhydride is preferably used as a terminal blocking agent for the acid component, and monoamine is preferably used as a terminal blocking agent for the amine component. At this time, it is preferable that the acid equivalent of the tetracarboxylic acid component including the terminal blocking agent of the acid component or the amine component and the amine equivalent of the diamine component be equimolar.
[0063]
When the molar ratio is adjusted so that the tetracarboxylic acid component is excessive or the diamine component is excessive, dicarboxylic acids such as benzoic acid, phthalic anhydride, tetrachlorophthalic anhydride, and aniline or their anhydrides and monoamines are capped. It may be added as a stopping agent.
[0064]
In the present invention, the molar ratio of the tetracarboxylic acid component / diamine component of the polyimide resin is usually 100/100. However, if the viscosity of the resin solution is too high, 100/100 to 95 or 100 to 95/100. It is preferred that the molar balance of the tetracarboxylic acid component / diamine component be adjusted in the range described above so that the viscosity of the resin solution falls within a range in which there is no problem in coatability and the like. However, as the molar balance is lost, the molecular weight of the resin decreases, the strength of the cured film decreases, and the adhesive strength with the conductive metal layer tends to decrease. It is preferable to adjust the molar ratio within a range that does not become weak.
[0065]
In the present invention, polyamic acid, which is one of the precursors of the polyimide resin, is synthesized by a known method. For example, it can be synthesized by selectively combining a tetracarboxylic acid component and a diamine component, and reacting the mixture at a predetermined molar ratio in a solvent at 0 to 80 ° C.
[0066]
At this time, a monoamine for sealing the polymer chain terminal, a dicarboxylic acid or an anhydride thereof may be charged and reacted at the same time as a tetracarboxylic dianhydride or a diamine, or a tetracarboxylic dianhydride or a diamine. After reacting and polymerizing, it may be added and reacted.
[0067]
Examples of the solvent for synthesizing the polyamic acid include amide polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, β-propiolactone, γ-butyrolactone, Lactone-based polar solvents such as γ-valerolactone, δ-valerolactone, γ-caprolactone, and ε-caprolactone, as well as methyl cellosolve, ethyl cellosolve, methyl carbitol, ethyl carbitol and the like can be mentioned. These may be used alone or as a mixture of two or more.
[0068]
The concentration of the polyamic acid is usually preferably 5 to 60% by weight, more preferably 10 to 40% by weight.
[0069]
In the present invention, other resins and fillers can be added to the heat-resistant resin used for the heat-resistant resin layer, as long as the effects of the present invention are not impaired. Other resins include heat-resistant polymer resins such as acrylonitrile-based resins, butadiene-based resins, urethane-based resins, polyester-based resins, polyamide-based resins, polyamide-imide-based resins, epoxy-based resins, and phenol-based resins. Examples of the filler include organic or inorganic fine particles and fillers. Specific examples of the fine particles and the filler include silica, alumina, titanium oxide, quartz powder, magnesium carbonate, potassium carbonate, and barium sulfate.
[0070]
The glass transition temperature of the heat-resistant resin used in the heat-resistant resin layer of the present invention is preferably in the range of 140 to 240 ° C, preferably 145 to 220 ° C, and more preferably 150 to 200 ° C. If the glass transition temperature is higher than 240 ° C., the initial adhesive strength with the conductive metal layer becomes low, so that the adhesiveness generally deteriorates. If the glass transition temperature is lower than 140 ° C., the adhesive strength after the moist heat resistance test is significantly reduced. I do.
[0071]
Next, a method for laminating a heat-resistant insulating film and a heat-resistant resin layer will be described in detail through an example of obtaining a printed circuit board of the present invention.
[0072]
As a heat-resistant insulating film, a resin solution containing a polyamic acid varnish is uniformly applied on a polyimide film that has been subjected to a low-temperature plasma treatment or a corona discharge treatment in order to provide a heat-resistant resin layer. Examples of the coating method include a roll coater, a knife coater, a sealing coater, a comma coater, and a doctor blade float coater. Next, the solvent of the solution applied to the heat-resistant insulating film as described above is usually heated and removed continuously or intermittently at a temperature of about 60 to 200 ° C. for 1 to 60 minutes.
[0073]
The thickness of the heat-resistant resin layer formed on the polyimide film which is a heat-resistant insulating film is preferably 0.05 to 10 μm, more preferably 0.1 to 8 μm, and particularly preferably 0.4 to 5 μm, It can be appropriately selected according to the purpose.
[0074]
In order to improve the adhesiveness, it is preferable to further perform heat curing. The condition for the heating cure is usually from 200 to 350 ° C. for 1 minute to 60 minutes, but can be appropriately selected depending on the resin composition, film thickness and the like.
[0075]
The conductive metal layer in the present invention is not particularly limited as long as it is composed of a metal having excellent conductivity. Examples of the metal species include aluminum, copper, palladium, nickel, chromium, SUS, Although metals such as cobalt and gold or alloys thereof can be used, copper is preferable in terms of excellent electrical characteristics, and it is preferable that a plating layer is formed mainly of copper. Here, the main component means 90% by weight or more.
[0076]
The conductive metal layer may be a multilayer. For example, a thin metal is formed on the surface of the heat-resistant resin layer by vapor deposition or sputtering, and a metal layer of the same or different kind is formed thereon by plating. When the conductive metal layer is a multilayer, the thickest layer (or sometimes referred to as a main component layer) preferably contains copper as a main component. Further, it is preferable that the entire conductive metal layer contains 90% by weight or more of copper.
[0077]
The conductive metal layer needs to include a plating layer. In particular, when copper is used, a copper plating layer is preferable from the viewpoint of easy control of film characteristics and thickness.
[0078]
In the plating layer, generally, crystals developed in the thickness direction are observed in a cross-sectional crystal image by an electron microscope. The length of the crystal in the thickness direction is preferably 90% or more, more preferably 95% or more of the thickness of the metal layer or the main component layer.
[0079]
The electroplating method for forming the plating layer is not particularly limited, and an ordinary copper sulfate plating method can be used. In the case of a conductive metal layer, particularly a copper layer, the thickness is preferably in the range of 1 to 18 μm. If it is thinner than 1 μm, pinholes are likely to occur, and if it is thicker than 18 μm, it becomes difficult to control the thickness of plated copper. More preferably, it is 2 to 12 μm.
[0080]
The thicknesses of the heat-resistant resin layer and the conductive metal layer can be measured by various known methods. In the present invention, for example, the thickness of the heat-resistant resin layer and the conductive resin layer can be measured by observing the cross section of the obtained printed circuit board with an SEM. In the case of a conductive metal layer, for example, it can be calculated from the difference in film thickness between the portion where the conductive metal layer remains after etching the wiring pattern and the etched portion. In the case of a heat-resistant resin layer, for example, the thickness can be calculated by measuring the film thickness of the portion of the printed circuit board where the conductive metal layer is etched, and subtracting the known film thickness of the heat-resistant insulating film.
[0081]
The conductive metal layer in the present invention preferably has a different component layer usually made of nickel, chromium, or the like on the side in contact with the heat-resistant resin layer, and the thickness thereof is preferably 2 nm to 30 nm. The heterogeneous component layer may contain copper or the like, or may be distributed with a component concentration gradient in the thickness direction. After the heterogeneous component layer is formed, it is preferable to further laminate a copper layer by sputtering or vapor deposition at 50 nm or more. In this case, it is preferable that the total thickness of the copper layer laminated with the different component layer by sputtering or the like be 400 nm or less.
[0082]
The above-mentioned heterogeneous component layer itself or a case where a main component (eg, copper) layer laminated on the heterogeneous component layer by sputtering or vapor deposition (hereinafter, simply referred to as a sputter main component layer) is referred to as a metal base layer. That is, the metal base layer is composed of a heterogeneous component layer or a heterogeneous component layer / sputter main component layer. In the present invention, since the plating layer is essential, the main component layer is preferably provided by plating. In this case, if the metal base layer is thinner than 2 nm, pinholes may occur frequently. On the other hand, if it is thicker than 400 nm, it takes a long time to form the conductive metal layer. It is particularly preferable to form a copper layer having a thickness of 1 to 18 μm on the metal base layer by an electroplating method.
[0083]
In the present invention, heat treatment may be further performed after sputtering or plating. The condition of the heat treatment is usually from 200 ° C. to 350 ° C. for 10 minutes to 48 hours, but can be appropriately selected depending on the resin composition, film thickness and the like. At this time, the temperature may be increased stepwise to the target temperature. In addition, cooling may be performed stepwise.
[0084]
Further, in the present invention, before the sputtering, the surface of the heat-resistant resin layer is subjected to a surface modification treatment such as a normal pressure plasma treatment, a corona discharge treatment, and a low-temperature plasma treatment to further increase the adhesive strength with the conductive metal layer. Can be. In particular, it is effective to perform low-temperature plasma treatment, and the method is not particularly limited. For example, the substrate to be treated is placed in an internal electrode type discharge treatment apparatus having a drum electrode and a counter electrode composed of a plurality of rod electrodes. The material is set, and a processing gas is adjusted to 1 to 1000 Pa, preferably 5 to 100 Pa, and a high voltage of direct current or alternating current is applied between the electrodes to perform discharge to generate plasma of the processing gas. For example, a method of exposing the surface of the base material to a treatment is preferably used. The conditions for the low-temperature plasma processing vary depending on the processing apparatus, the type of the processing gas, the pressure, the frequency of the power supply, and the like, but the optimum conditions can be appropriately selected. As the type of the processing gas, for example, Ar, N ₂ , He, CO ₂ , CO, air, water vapor, O ₂ , CF ₄ Etc. can be used alone or in combination.
[0085]
In the present invention, the adhesive strength is measured by a peel strength when a metal foil is peeled off at a rate of 50 mm / min in a direction of 90 degrees using a pattern having a conductor width of 2 mm.
[0086]
For example, a "two-layer plating" product in which a copper layer is laminated on a heat-resistant insulating film by a plating method has a flat adhesive interface with the copper layer, and the above-described measuring method usually has an adhesive strength of about 5 N / cm. In the case of the printed circuit board of the present invention, since the metal layer is formed by the plating method, the bonding interface of the metal layer is flat, but, for example, an adhesive force of 8 N / cm or more can be obtained. Further, since the heat-resistant adhesive layer is thin, there is an advantage that the properties inherent in the heat-resistant insulating film are not impaired.
[0087]
The printed circuit board of the present invention uses the above-described printed circuit board. Specifically, for example, a resist layer is formed on a conductive metal layer of a printed circuit board, and the resist layer is exposed and developed to pattern the resist into a shape matching the wiring pattern, and the patterned resist is etched. It is obtained by etching a conductive metal layer as a mask to form a wiring pattern, and removing the resist after forming the wiring pattern.
[0088]
When the copper foil is etched, the cross section of the wiring pattern of the obtained printed circuit board is also etched in the width direction while being etched in the thickness direction (side etching), so that the line width of the top (copper foil surface) is obtained. Tends to have a tapered shape narrower than the line width of the bottom (the surface in contact with the base film). When the thickness of the copper foil is increased, the side etching tends to be increased. Therefore, the thickness is preferably in the above-described range. For example, in the case of a wiring pattern having a pitch of 80 μm (wiring width of 40 μm, gap of 40 μm), if the top line width is 20 μm or more with respect to the bottom line width of 40 μm, a good pattern shape may cause a bonding failure when mounting a semiconductor. Does not appear. If the top line width is smaller than 20 μm, a bonding failure tends to occur when mounting a semiconductor.
[0089]
The printed circuit board of the present invention may have a conductive metal layer on one or both sides of a heat-resistant insulating film. Therefore, a single-sided or double-sided wiring board can be formed by forming a wiring using a semi-additive method or a subtractive method.
[0090]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. The adhesion, wet heat resistance test, heat load test, heat load test after tin plating, and measurement of the glass transition temperature were evaluated and measured by the following methods.
[0091]
(1) Adhesiveness
After laminating the metal layer, the metal layer is etched to a width of 2 mm with a ferric chloride solution, and the metal layer having a width of 2 mm is pulled at a tension rate of 50 mm / min., 90 ° using “Tensilon” UTM-4-100 manufactured by TOYO BOLDWIN. It was measured by peeling.
[0092]
(2) Moisture and heat resistance test
After laminating the metal layer, the metal layer was etched with a ferric chloride solution to a width of 2 mm, placed in a high-temperature and high-humidity oven set at 121 ° C./100% RH / 2 atm for 96 hours, and taken out. The adhesiveness as described in was evaluated.
[0093]
(3) Heat load test
After laminating the metal layer, the metal layer was etched to a width of 2 mm with a ferric chloride solution, placed in a hot-air oven set at 150 ° C. for 240 hours, taken out, and tested for adhesion as described in (1). evaluated.
[0094]
(4) Heat load test after tin plating
After laminating the metal layer, the metal layer is etched to a width of 2 mm with a ferric chloride solution, and then electroless tin plating is performed using a tin plating solution LT-34 manufactured by Tokyo Ohka Co., Ltd. at a solution temperature of 70 ° C. and a plating time of 5 minutes. Then, it was washed and dried. After being placed in a hot air oven set at 150 ° C. for 240 hours, it was taken out and evaluated for adhesiveness as described in (1).
[0095]
(5) Measurement of glass transition temperature
The heat-resistant resin solution was applied to the glossy surface of the copper foil, and dried at 120 ° C. for 10 minutes in a hot-air oven. Next, using an inert oven, heat curing was performed at 280 ° C. for 1 hour in a nitrogen atmosphere. After the obtained sample was immersed in a ferric chloride etching solution to etch the entire surface of the copper foil, the sample was washed with running water and dried to obtain a single film of a heat-resistant resin.
[0096]
Approximately 10 mg of the obtained heat-resistant resin single film was packed in a standard aluminum container, and measured using a differential scanning calorimeter DSC-50 (manufactured by Shimadzu Corporation) (DSC method). The glass transition temperature was calculated from the inflection point. After preliminary drying at 80 ° C. × 1 hour, the measurement was performed at a temperature rising rate of 20 ° C./min.
[0097]
Production Example 1
2048 g of N, N-dimethylacetamide was placed in a reaction vessel equipped with a thermometer, a dry nitrogen inlet, a heating / cooling device using hot / cold water, and a stirrer, and bis (3-aminopropyl) tetramethyl was added under a nitrogen stream. After dissolving 99.4 g (0.4 mol) of disiloxane, 2.2 g (0.02 mol) of p-phenylenediamine, and 116.1 g (0.58 mol) of 4,4′-diaminodiphenyl ether, 3,3 ′, 294.2 g (1 mol) of 4,4′-biphenyltetracarboxylic dianhydride was added, and the mixture was stirred at 30 ° C. for 1 hour, and then stirred at 60 ° C. for 5 hours to react. (PA1) was obtained.
[0098]
The glass transition temperature of the resin obtained by imidizing the polyamic acid resin solution PA1 was 180 ° C.
[0099]
Production Examples 2-36
The same operation as in Production Example 1 was performed except that the tetracarboxylic acid component, the diamine component, and the solvent shown in Tables 1 and 2 were used to obtain a 20% by weight polyamic acid resin solution (PA2 to 36). Tables 1 and 2 also show the glass transition temperature of the resin obtained by imidizing the obtained polyamic acid resin solution.
[0100]
[Table 1]

[0101]
[Table 2]

[0102]
OSida and PSida are silicon diamines represented by the general formula (6), and OSida is a silicon diamine having an amine equivalent of 235. PSiDA is Silicon Diamine BY16-853 manufactured by Toray Dow Corning Silicone Co., Ltd. having an amine equivalent of 650.
[0103]
Embedded image

[0104]
Here, n represents an integer of 1 to 30.
[0105]
Example 1
The polyamic acid resin solution (PA1) prepared in Production Example 1 was applied to a 25 μm polyimide film (“Kapton” 100EN manufactured by Du Pont-Toray Co., Ltd.) that had been previously subjected to low-temperature plasma treatment in an Ar atmosphere, and the film thickness after drying was 2 μm. And dried at 130 ° C. for 10 minutes at 100 ° C. for 5 minutes. The coated product was subjected to a heat treatment at 290 ° C. for 30 minutes to perform imidization and removal of a residual solvent.
[0106]
A Ni / Cr (composition ratio: 80/20 (wt%)) layer was formed to a thickness of 8 nm on the heat-resistant resin-coated surface of the produced film using a sputtering apparatus (SPL-500 manufactured by Nidec Anelva Co., Ltd.) A copper layer was formed thereon with a thickness of 200 nm by sputtering. Immediately after sputtering, a copper sulfate bath was used, and the current density was 2 A / dm. ² Under the above conditions, plating was performed so that the copper thickness became 8 μm, to obtain a printed circuit board. Table 3 shows the evaluation results of the adhesive strength.
[0107]
Examples 2 to 22
A printed circuit board was obtained in the same manner as in Example 1, except that the composition of the heat-resistant resin layer and the film thickness after drying were changed as shown in Table 3. Table 3 shows the evaluation results of the adhesive strength.
[0108]
Comparative Examples 1 to 19
A printed circuit board was obtained in the same manner as in Example 1, except that the composition of the heat-resistant resin layer and the film thickness after drying were changed as shown in Table 3. Table 3 shows the evaluation results of the adhesive strength.
[0109]
[Table 3]

[0110]
Example 23
The polyamic acid resin solution (PA2) prepared in Production Example 2 was applied to a 25 μm polyimide film (“UPILEX” 25S, manufactured by Ube Industries, Ltd.) that had been subjected to low-temperature plasma treatment in an Ar atmosphere in advance. Coating was performed with a bar coater so as to have a thickness of 5 μm, and the coating was dried at 100 ° C. for 5 minutes and further at 130 ° C. for 10 minutes. The coated product was subjected to a heat treatment at 290 ° C. for 30 minutes to perform imidization and removal of a residual solvent.
[0111]
A Ni / Cr (composition ratio: 80/20 (wt%)) layer was formed to a thickness of 8 nm on the heat-resistant resin-coated surface of the produced film using a sputtering apparatus (SPL-500 manufactured by Nidec Anelva Co., Ltd.) A copper layer was formed thereon with a thickness of 200 nm by sputtering. Immediately after sputtering, a copper sulfate bath was used, and the current density was 2 A / dm. ² Under the above conditions, plating was performed so that the copper thickness became 8 μm, to obtain a printed circuit board. Table 4 shows the evaluation results of the adhesive strength.
[0112]
Examples 24 to 30
A printed circuit board was obtained in the same manner as in Example 23, except that the composition of the heat-resistant resin layer and the film thickness after drying were changed as shown in Table 4. Table 4 shows the evaluation results of the adhesive strength.
[0113]
Comparative Examples 20 to 32
A printed circuit board was obtained in the same manner as in Example 23, except that the composition of the heat-resistant resin layer and the film thickness after drying were changed as shown in Table 4. Table 4 shows the evaluation results of the adhesive strength.
[0114]
[Table 4]

[0115]
From the above results, all of the products of the present invention can obtain a high initial adhesive strength between the base film and the plated copper, and have a small decrease in the adhesive strength after the heat load test and after the moist heat resistance test, and furthermore, the adhesive strength after tin plating. The decrease was small. On the other hand, the printed circuit board of the comparative example had a low initial adhesive strength, a large decrease in the adhesive strength after the heat load test and the moisture and heat resistance test, and a large decrease in the adhesive strength after the tin plating.
[0116]
Example 31
The polyamic acid resin solution (PA2) prepared in Production Example 2 was applied to a 25 μm polyimide film (“Kapton” 100EN manufactured by Du Pont-Toray Co., Ltd.) that had been previously subjected to low-temperature plasma treatment in an Ar atmosphere to have a thickness of 2 μm after drying. And dried at 130 ° C. for 10 minutes at 100 ° C. for 5 minutes. The coated product was subjected to a heat treatment at 290 ° C. for 30 minutes to perform imidization and removal of a residual solvent.
[0117]
A Ni / Cr (composition ratio: 80/20 (wt%)) layer was formed to a thickness of 8 nm on the heat-resistant resin-coated surface of the produced film using a sputtering apparatus (SPL-500 manufactured by Nidec Anelva Co., Ltd.) A copper layer was formed thereon with a thickness of 200 nm by sputtering. Immediately after sputtering, a copper sulfate bath was used, and the current density was 2 A / dm. ² The plating was performed so that the copper thickness was 8 μm under the conditions described above. After plating, heat treatment was performed at 260 ° C. for 2 hours in a nitrogen atmosphere to obtain a printed circuit board. Table 5 shows the evaluation results of the adhesive strength.
[0118]
Example 32
The polyamic acid resin solution (PA14) prepared in Production Example 14 was dried at a low film thickness of 2 μm on a 25 μm polyimide film (“Kapton” 100EN manufactured by Du Pont-Toray Co., Ltd.) previously subjected to low-temperature plasma treatment in an Ar atmosphere. And dried at 130 ° C. for 10 minutes at 100 ° C. for 5 minutes. The coated product was subjected to a heat treatment at 290 ° C. for 30 minutes to perform imidization and removal of a residual solvent.
[0119]
A Ni / Cr (composition ratio: 80/20 (wt%)) layer was formed to a thickness of 8 nm on the heat-resistant resin-coated surface of the produced film using a sputtering apparatus (SPL-500 manufactured by Nidec Anelva Co., Ltd.) A copper layer was formed thereon with a thickness of 200 nm by sputtering. After performing a heat treatment at 260 ° C. for 2 hours in a nitrogen atmosphere after the sputtering, a current density of 2 A / dm. ² Under the above conditions, plating was performed so that the copper thickness became 8 μm to obtain a printed circuit board. Table 5 shows the evaluation results of the adhesive strength.
[0120]
Example 33
The polyamic acid resin solution (PA5) prepared in Production Example 5 was dried on a 25 μm polyimide film (“Kapton” 100EN manufactured by Du Pont-Toray Co., Ltd.), which had been previously subjected to low-temperature plasma treatment in an Ar atmosphere. Coating was performed with a bar coater so that the thickness became 2 μm, and the coating was dried at 100 ° C. for 5 minutes and further at 130 ° C. for 10 minutes. The coated product was subjected to a heat treatment at 290 ° C. for 30 minutes to perform imidization and removal of a residual solvent.
[0121]
After the surface of the heat-resistant resin layer is subjected to low-temperature plasma treatment in an Ar atmosphere, a Ni / Cr (composition ratio: 80/20 (composition ratio) is applied to the heat-resistant resin coated surface using a sputtering apparatus (SPL-500 manufactured by Nidec Anelva Co., Ltd.)). wt%)) layer was provided with a thickness of 8 nm, and then a copper layer was laminated thereon by sputtering to a thickness of 200 nm. Immediately after sputtering, a copper sulfate bath was used, and the current density was 2 A / dm. ² Under the above conditions, plating was performed so that the copper thickness became 8 μm to obtain a printed circuit board. Table 5 shows the evaluation results of the adhesive strength.
[0122]
Comparative Example 33
A printed circuit board was obtained in the same manner as in Example 31, except that the polyamic acid resin solution (PA20) prepared in Production Example 20 was used. Table 5 shows the evaluation results of the adhesive strength.
[0123]
Comparative Example 34
A printed circuit board was obtained by performing the same operation as in Example 32 except that the polyamic acid resin solution (PA29) prepared in Production Example 29 was used. Table 5 shows the evaluation results of the adhesive strength.
[0124]
Comparative Example 35
A printed circuit board was obtained by performing the same operation as in Example 33 except that the polyamic acid resin solution (PA34) prepared in Production Example 34 was used. Table 5 shows the evaluation results of the adhesive strength.
[0125]
[Table 5]

[0126]
Heat treatment after copper plating or copper sputtering, or plasma treatment of the surface of the heat-resistant resin layer before sputtering, resulted in high adhesion to plated copper. Further, after the heat load test, the decrease in the adhesive force after the moist heat resistance test was small, and also after the tin plating, the decrease in the adhesive force was small.
[0127]
Example 34
A photoresist film was applied on the copper foil of the printed circuit board obtained in Example 3 by a reverse coater so that the film thickness after drying was 4 μm, and after drying, the wiring pattern was 80 μm pitch (wiring width 40 μm, gap width 40 μm). After the mask exposure was performed to form a wiring pattern with an alkaline developer, the copper foil was wet-etched with an aqueous ferric chloride solution. The remaining photoresist film was removed to form a copper wiring pattern to obtain a printed circuit board.
[0128]
The wiring pattern of the printed circuit board obtained by the above method was observed with a microscope, and the bottom and top line widths of the copper wiring were measured. The bottom line width was 39 μm and the top line width was 32 μm. I got a pattern.
[0129]
Comparative Example 36 (Three-layer laminate product)
Henkel Japan Co., Ltd. polyamide resin "Macromelt" 6030 250 g (50 weight), Yuka Shell Epoxy Co., Ltd. epoxy resin "Epicoat" 828 105 g (21 wt%), Showa Kogaku Co., Ltd. 145 g (29% by weight) of phenolic resin CKM-1636 was dissolved in 680 g of isopropyl alcohol and 1760 g of chlorobenzene to obtain a 17% by weight polyamide / epoxy / phenolic adhesive solution.
[0130]
The obtained polyamide / epoxy / phenol-based adhesive solution was dried on a 25 μm-thick polyimide film (“Kapton” 100EN manufactured by Du Pont-Toray Co., Ltd.) which had been previously subjected to low-temperature plasma treatment in an argon atmosphere. Coating was performed with a reverse coater so that the film thickness became 6 μm, and dried at 80 ° C. for 10 minutes and further at 130 ° C. for 30 minutes.
[0131]
After preliminarily drying at 80 ° C. for 5 minutes on the adhesive-coated surface of the produced film, an electrolytic copper foil having a thickness of 18 μm was laminated with a roll laminator heated to a surface temperature of 140 ° C. at a linear pressure of 2 kg / cm and a speed of 1 m / min. Further, after performing heating step curing [(60 ° C., 30 minutes) + (100 ° C., 1 hour) + (160 ° C., 2 hours)] in a nitrogen atmosphere, the substrate is gradually cooled to room temperature to obtain a printed circuit board. Was.
[0132]
The same operation as in Example 34 was performed on the printed circuit board to obtain a printed circuit board. The wiring pattern of the printed circuit board obtained by the above method was observed with a microscope, and the bottom and top line widths of the copper wiring were measured. The bottom line width was 38 μm and the top line width was 12 μm. Was inferior in shape.
[0133]
Comparative Example 37 (2-layer cast product)
2090 g of N, N-dimethylacetamide was placed in a reactor equipped with a thermometer, a dry nitrogen inlet, a heating / cooling device using hot / cold water, and a stirrer, and 4,4′-diaminodiphenyl ether 200. After dissolving 2 g (1 mol), 322.2 g (1 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride was added, stirred at 30 ° C. for 1 hour, and then stirred at 60 ° C. for 5 hours. As a result, a 20% by weight polyamic acid solution was obtained.
[0134]
The obtained polyamic acid solution was applied on an uneven surface of an electrolytic copper foil having a thickness of 18 μm with a reverse coater so that the film thickness after curing became 25 μm, and dried at 80 ° C. for 10 minutes and at 140 ° C. for 30 minutes. . Thereafter, heat curing was performed at 290 ° C. for 30 minutes to obtain a printed circuit board.
[0135]
The same operation as in Example 34 was performed on the printed circuit board to obtain a printed circuit board. The wiring pattern of the printed circuit board obtained by the above method was observed with a microscope, and the bottom and top line widths of the copper wiring were measured. The bottom line width was 41 μm and the top line width was 16 μm. Was inferior in shape.
[0136]
【The invention's effect】
According to the present invention, the initial adhesive strength with the conductive metal layer formed on the heat-resistant film, the adhesive strength after the heat load, the adhesive strength after the wet heat resistance test is generally high, furthermore, after electroless tin plating It is possible to provide a plating type printed circuit board having high adhesive strength and excellent adhesiveness, and by using the printed circuit board, it is possible to obtain a high-density and highly reliable circuit board. , Its practicality is enormous.

Claims (9)

A printed circuit board in which a heat-resistant resin layer and a conductive metal layer are sequentially laminated on at least one surface of a heat-resistant insulating film, wherein the heat-resistant resin is a polyimide resin including an aromatic tetracarboxylic acid component and a diamine component. A tetracarboxylic acid in which the polyimide-based resin contains an aromatic tetracarboxylic acid having at least one of the skeletons represented by the general formulas (1) to (3) in an amount of 60 mol% or more of the total aromatic tetracarboxylic acid component; Component and at least 5 to 50 mol% of the siloxane-based diamine represented by the general formula (4) in the total diamine component, and 0.1 to 40 mol% of the diamine having one aromatic ring in the total diamine component. A printed circuit board which is a polyimide-based resin obtained by polymerizing a diamine component and in which a conductive metal layer includes a plating layer.

(However, n in the general formulas (1) to (3) each represents an integer of 0 to 4.)

(However, n in the general formula (4) represents an integer of 1 to 30. R ¹ and R ² may be the same or different and each represents a lower alkylene group or a phenylene group. R ^{3 to} R ⁶ May be the same or different, and represent a lower alkyl group, a phenyl group or a phenoxy group.) The printed circuit board according to claim 1, wherein the aromatic tetracarboxylic acid is a tetracarboxylic acid having a biphenyl skeleton. 3. The printed circuit board according to claim 2, wherein the aromatic tetracarboxylic acids are 3,3 ', 4,4'-biphenyltetracarboxylic acids. The printed circuit board according to claim 1, wherein the diamine having one aromatic ring is paraphenylenediamine. The printed circuit board according to claim 1, further comprising a diamine represented by the general formula (5) in the diamine component.

(Where X represents O, S, SO, SO ₂ , C ＝ O, CH ₂ ) The printed circuit board according to claim 1, wherein the glass transition temperature of the resin of the heat-resistant resin layer is in the range of 140 to 240C. 2. The printed circuit board according to claim 1, wherein the thickness of the heat-resistant resin layer is in the range of 0.05 to 10 [mu] m. 2. The printed circuit board according to claim 1, wherein the conductive metal layer is mainly composed of copper and has a thickness in a range of 1 to 18 [mu] m. A printed circuit board using the printed circuit board according to claim 1.