JP4019800B2

JP4019800B2 - Insulating resin composition manufacturing method, insulating resin composition, multilayer wiring board and manufacturing method thereof

Info

Publication number: JP4019800B2
Application number: JP2002162817A
Authority: JP
Inventors: 伸高根沢; 高示森田; 貴子渡▲辺▼
Original assignee: Hitachi Chemical Co Ltd; Showa Denko Materials Co Ltd
Current assignee: Showa Denko Materials Co Ltd
Priority date: 2002-06-04
Filing date: 2002-06-04
Publication date: 2007-12-12
Anticipated expiration: 2022-06-04
Also published as: JP2004010660A

Description

【０００１】
【発明の属する技術分野】
本発明は、絶縁樹脂組成物の製造方法、絶縁樹脂組成物、多層配線板およびその製造方法に関する。
【０００２】
【従来の技術】
多層配線板を製造するには、片面または両面に内層回路を形成した絶縁基板上に、プリプレグと呼ばれるガラス布にエポキシ樹脂を含浸し半硬化状態にした材料を銅箔と重ねて熱プレスにより積層一体化した後、ドリルで層間接続用のスルーホールと呼ばれる穴をあけ、スルーホール内壁と銅箔表面上に無電解めっきを行って、必要ならば更に電解めっきを行って回路導体として必要な厚さとした後、不要な銅を除去して多層配線板を製造するのが一般的であった。
ところで、近年、電子機器の小型化、軽量化、多機能化が一段と進み、これに伴い、ＬＳＩやチップ部品等の高集積化が進みその形態も多ピン化、小型化へと急速に変化している。この為、多層配線板は、電子部品の実装密度を向上するために、微細配線化の開発が進められている。これらの要求に合致する多層配線板の製造手法として、ガラスクロスを含まない絶縁樹脂をプリプレグの代わりに絶縁層として用い、必要な部分のみビアホールで接続しながら配線層を形成するビルドアップ方式の多層配線板があり、軽量化や小型化、微細化に適した手法として主流になりつつある。
【０００３】
また、環境意識の高まりから燃焼時に有害な物質を発生する可能性がある材料は電子部品も含めて規制する動きが活発になっている。従来の多層配線板には、燃焼時に有害な物質を発生する可能性があるブロム化合物が難燃化のために使用されてきたが近い将来使用が困難になると予想される。
さらに、電子部品を多層配線板に接続するために一般的に用いられるはんだも鉛を有さない鉛フリーはんだが実用化されつつある。この鉛フリーはんだは、従来の共晶はんだよりも使用温度が約２０〜３０℃高くなることから従来にもまして材料には高いはんだ耐熱性が必要になっている。
【０００４】
このように、多層配線板に要求される項目は年々厳しくなり、特に基板と回路を接続する重要な役割をもつ絶縁層は更なる高性能化が必要になる。
しかしながら、多層配線板の薄型化のためにガラスクロスを含まない絶縁樹脂層は、ガラスクロスを含まないために絶縁樹脂の機械的物性の善し悪しが多層配線板の特性に大きく影響する。具体的には、絶縁樹脂が硬くて伸びが小さく脆い性質の場合、多層配線板の製品サイズへの打ち抜き加工時の機械的なストレスにより絶縁樹脂にクラックや欠けが生じ導通あるいは絶縁信頼性に大きな支障を与えることになる。また、機器の小型化や多機能化を達成するために電子部品が面実装型へ移行することで絶縁樹脂と電子部品の距離が狭小化し、絶縁樹脂には電子部品の熱的な応力が集中しやすくなってきた。すなわち、絶縁樹脂が硬くて伸びが小さく脆い性質の場合は、電子部品やそれを多層配線板と接続させるはんだや銅の熱的な応力集中により絶縁樹脂内部やはんだや銅にクラックを発生しやすくさせてしまう。
このようなことから、絶縁樹脂には機械的や熱的な応力集中に耐えられるような変形すなわち引っ張り伸び率が大きい性質が要求されるようになってきた。
【０００５】
【発明が解決しようとする課題】
しかし、引っ張り伸び率を大きくする手法としては一般に熱可塑性の高分子量成分を導入する手法がとられるが高分子量成分を導入するとガラス転移点の低下は避けられないのが通例であった。
また、環境に影響しないようにブロム化合物を使用せずに、高い絶縁信頼性を有する絶縁樹脂は現段階で開発されていないのが実状である。その理由としては、高い難燃性やはんだ耐熱性を得るためにはフィラー型の難燃剤を用いる必要があるが一般にフィラー型の難燃剤は溶剤に溶解しづらく分散性が悪くなるためである。すなわち、分散性が悪いと、絶縁層に電気を流しやすい粒界が発生しやすくなったり、部分的に難燃剤が欠落することによって絶縁距離が小さくなりやすいからである。
さらに、電子機器の小型化、高機能化が進み配線板の微細化が進んでいる。この微細配線化には回路導体のエッチング精度の点から絶縁樹脂と回路導体を接着する界面の粗さをできるだけ小さく必要がある。このため、最近では銅箔メーカから銅箔の粗化後の表面粗さＲｚが従来の７〜８μｍから３〜４μｍのような低粗化箔が実用化されてきた。しかしながら、絶縁樹脂と回路導体を接着する界面の粗さは絶縁樹脂と回路導体との接着強度に重要な影響を与えており、界面の粗さが小さくなるほど接着強度は低下してしまう。このため、低粗さでも高い接着強度を発現できる絶縁樹脂が必要になっている。
【０００６】
本発明は、環境に悪影響を与える可能性があるブロム化合物を一切使用しないで難燃性を有し、さらに難燃剤の分散不良をなくして絶縁性を高め、また鉛フリー化に対応可能な高いはんだ耐熱性と機械的や熱的な応力集中に耐えられるような絶縁樹脂塗膜の高伸びを実現させ、さらに微細配線化に対応可能なように粗化後の粗さが低い絶縁樹脂を用いた多層配線板の製造方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明者らはこのような問題を解決するために研究を進めた結果、多層配線板における絶縁層として、絶縁樹脂にビフェニル構造及びノボラック構造を有したエポキシ樹脂とアクリロニトリルブタジエンの共重合物とリン含有フェノール樹脂と熱硬化剤とを必須として含んだ絶縁樹脂を用い、さらに難燃剤の分散不良をなくして絶縁性を高めることで、環境に悪影響を与える可能性があるブロム化合物を一切使用しないで難燃性を有し、鉛フリー化に対応可能な高いはんだ耐熱性と機械的や熱的な応力集中に耐えられるような絶縁樹脂塗膜の高伸びを実現させ、さらに微細配線化に対応可能な絶縁信頼性を有した絶縁樹脂組成物を見出すことができた。
【０００８】
すなわち、本発明は、（１）（Ａ）ビフェニル構造及びノボラック構造を有したエポキシ樹脂と、（Ｂ）アクリロニトリルブタジエン共重合物と、（Ｃ）リン含有フェノール樹脂と、（Ｄ）熱硬化剤と、（Ｅ）溶解性パラメータが７．５〜１０．５の範囲にある溶剤とを含む絶縁樹脂組成物の製造方法であって、
予め（Ｅ）溶解性パラメータが７．５〜１０．５の範囲にある溶剤の少なくとも一部を含む液中に（Ｃ）リン含有フェノール樹脂を分散してリン含有フェノール樹脂の分散液を得る工程を含むことを特徴とする絶縁樹脂組成物の製造方法に関する。
【０００９】
また、本発明は、（２）分散液を得る工程において、前記溶剤の少なくとも一部を含む液中に（Ｆ）界面活性剤を加える前記（１）記載の絶縁樹脂組成物の製造方法に関する。
本発明は、（３）前記分散液中のリン含有フェノール樹脂の濃度が固形分で１０〜６０重量％の範囲にある前記（１）または（２）記載の絶縁樹脂組成物の製造方法に関する。
【００１０】
また、本発明は、（４）前記（１）〜（３）のいずれか記載の製造方法により製造されてなる絶縁樹脂組成物に関する。
【００１１】
さらに、本発明は、（５）（Ａ）ビフェニル構造及びノボラック構造を有したエポキシ樹脂と、（Ｂ）アクリロニトリルブタジエン共重合物と、（Ｃ）リン含有フェノール樹脂と、（Ｄ）熱硬化剤と、（Ｅ）溶解性パラメータが７．５〜１０．５の範囲にある溶剤とを含む絶縁樹脂組成物に関する。
本発明は、（６）さらに（Ｆ）界面活性剤を含む前記（５）記載の絶縁樹脂組成物に関する。
本発明は、（７）（Ｅ）溶解性パラメータが７．５〜１０．５の範囲にある溶剤の少なくとも一部を含む液中に予め（Ｃ）リン含有フェノール樹脂を分散させた分散液を用いてなる前記（５）または（６）記載の絶縁樹脂組成物に関する。
本発明は、（８）前記分散液に（Ｆ）界面活性剤が含まれる前記（７）記載の絶縁樹脂組成物に関する。
本発明は、（９）前記分散液中のリン含有フェノール樹脂の濃度が固形分で１０〜６０重量％の範囲にある前記（７）または（８）記載の絶縁樹脂組成物に関する。
【００１２】
本発明は、（１０）前記（Ａ）ビフェニル構造及びノボラック構造を有したエポキシ樹脂が絶縁樹脂組成物の全固形分中の割合で３５〜６０重量％であり、かつ前記（Ａ）エポキシ樹脂と、（Ｂ）アクリロニトリルブタジエン共重合物との固形分配合比が重量比で８０／２０〜９５／５である前記（４）〜（９）のいずれか記載の絶縁樹脂組成物に関する。
本発明は、（１１）さらに（Ｇ）無機フィラーを含み、（Ｃ）リン含有フェノール樹脂中のリン含有量が（Ｇ）無機フィラーを除く絶縁樹脂組成物の固形分中で０．７〜３．０重量％である（４）〜（１０）のいずれか記載の絶縁樹脂組成物に関する。
【００１３】
また、本発明は、（１２）内層回路を有する基板の片面または両面に絶縁層及び外層回路層が逐次積層されている多層配線板であって、絶縁層が、（４）〜（１１）のいずれか記載の絶縁樹脂組成物が硬化してなる絶縁樹脂層を含むことを特徴とする多層配線板に関する。
【００１４】
本発明は、（１３）絶縁樹脂層の厚さが３０μｍ以下である前記（１２）記載の多層配線板に関する。
本発明は、（１４）絶縁樹脂層の引っ張り伸び率が４％以上である前記（１２）または（１３）記載の多層配線板に関する。
本発明は、（１５）絶縁樹脂層の外層回路層との界面の表面粗さが、Ｒｚで１〜３である前記（１２）〜（１４）のいずれか記載の多層配線板に関する。
【００１５】
さらに本発明は、（１６）前記（４）〜（１１）のいずれか記載の絶縁樹脂組成物の層を含む絶縁層を、内層回路を有する基板に積層する工程（イ）、絶縁樹脂組成物を硬化して絶縁樹脂層を得る工程（ロ）、絶縁層表面に外層回路層を形成する工程（ハ）、を含む多層配線板の製造方法に関する。
【００１６】
本発明は、（１７）前記工程（ロ）では、絶縁樹脂層を得た後に絶縁樹脂層表面を酸化性粗化液で粗化処理する工程を含む（１６）記載の多層配線板の製造方法に関する。
本発明は、（１８）前記工程（ハ）では、銅めっきにより外層回路を形成する前記（１６）または（１７）記載の多層配線板の製造方法に関する。
本発明は、（１９）前記工程（イ）では、絶縁樹脂組成物のワニスを支持体に塗布、乾燥して支持体付きフィルムを作製し、この支持体付き絶縁フィルムを内層回路を有する基板上に積層する前記（１６）〜（１８）のいずれか記載の多層配線板の製造方法に関する。
【００１７】
【発明の実施の形態】
まず、本発明の絶縁樹脂組成物およびその製造方法に用いられる各成分について説明する。
（Ａ）ビフェニル構造及びノボラック構造を有したエポキシ樹脂とは、分子中にビフェニル誘導体の芳香族環を含有したノボラック構造のエポキシ樹脂であり、日本化薬株式会社製のＮＣ−３０００Ｓ（商品名）やＮＣ−３０００Ｓ−Ｈ（商品名）が使用できる。
【００１８】
（Ａ）ビフェニル構造及びノボラック構造を有したエポキシ樹脂の配合量は、溶剤を除いた絶縁樹脂組成物の全固形分中の割合で３５〜６０重量％であるのが好ましく、かつ（Ａ）ビフェニル構造及びノボラック構造を有したエポキシ樹脂と（Ｂ）アクリロニトリルブタジエン共重合物との固形分配合比（重量比、以下同じ。）が８０／２０〜９５／５であるのが好ましい。前記（Ａ）成分の配合量が、３５重量％未満でははんだ耐熱性が低下し、６０重量％を超えると回路導体との接着強度が低下する傾向がある。また、（Ａ）成分と（Ｂ）成分との前記固形分配合比において、８０／２０よりも（Ａ）成分が減るとはんだ耐熱性が悪化し、逆に９５／５よりも（Ｂ）成分が増えると塗膜の引っ張り伸び率が低下する傾向がある。
【００１９】
（Ｂ）アクリロニトリルブタジエン共重合物は、アクリロニトリルとブタジエンとを共重合したNBRが挙げられ、アクリロニトリルとブタジエンとアクリル酸などのカルボン酸とを共重合したものも使用可能である。これらは、共重合する段階で架橋しないで得られる線状ＮＢＲと、部分的に架橋した粒子状ＮＢＲとの２種の混合物であるのが好ましい。この混合物の場合は、配合割合は、固形分比で同量付近が全ての特性面で良好であるが、例えば前記アクリロニトリルとブタジエンとカルボン酸を共重合した混合物の場合、線状ＮＢＲと粒子状ＮＢＲとの配合比が３／７〜８／２までが好適に使用可能である。この場合、線状ＮＢＲが配合比で３／７よりも減ると絶縁樹脂を塗布、乾燥後の塗膜に凹凸が生じ、逆に８／２よりも増えると粗化後の粗さが大きくなり微細粗化形状に適さなくなる傾向がある。
【００２０】
（Ｃ）リン含有フェノール樹脂は、２官能フェノール樹脂と有機リン化合物を反応して得られたものであり、例えば、三光株式会社製のＨＣＡ−ＨＱ（商品名）等が使用できる。その含有量は、リン含有％が後述する無機フィラーを除く絶縁樹脂組成物の固形分中で０．７〜３重量％の範囲になるようにするのが難燃性を発現するために好ましい。リン含有％が０．７％未満では難燃性の発現に不十分であり、リン含有％が３％を超えるとはんだ耐熱性が低下するためである。このリン含有フェノール樹脂は、絶縁信頼性の点から平均粒径が２μｍ付近のもので最大粒径が約６μｍ以下としたものを用いるのが好ましい。
【００２１】
（Ｄ）熱硬化剤は、ビフェニル構造及びノボラック構造を有したエポキシ樹脂中のエポキシ基及びビフェニル構造及びノボラック構造を有したエポキシ樹脂中のエポキシ基とリン含有フェノール樹脂の反応促進のために使用される。熱硬化剤は、各種フェノール樹脂類、酸無水物類、アミン類、ヒドラジット類などが使用できる。多官能フェノール類としては、ヒドロキノン、レゾルシノール、ビスフェノールＡ及びこれらのハロゲン化合物、さらにホルムアルデヒドとの縮合物であるノボラック型フェノール樹脂、レゾール型フェノール樹脂などが使用でき、酸無水物類としては、無水フタル酸、ベンゾフェノンテトラカルボン酸二無水物、メチルハイミック酸等が使用でき、アミン類として、ジシアンジアミド、ジアミノジフェニルメタン、グアニル尿素等が使用できる。回路導体との接着性からジシアンジアミドが好ましく、耐熱性や絶縁性も考慮するとジシアンジアミドとノボラックフェノールを併用することがさらに好ましい。
これらの熱硬化剤は、エポキシ基に対して０．５〜１．５当量であるのが好ましい。熱硬化剤がエポキシ基に対して０．５当量未満の場合は外層銅との接着性が低下し、１．５当量を超えるとＴgや絶縁性が低下する場合がある。
【００２２】
また、熱硬化剤の他に、必要に応じて反応促進剤を使用することができる。反応促進剤としては潜在性の熱硬化剤である各種イミダゾール類やBF₃アミン錯体が使用できる。さらに好ましくは、絶縁樹脂組成物の保存安定性やＢステージ状（半硬化状）の絶縁樹脂組成物の取り扱い性及びはんだ耐熱性の点から２−フェニルイミダゾールや２−エチル−４−メチルイミダゾールが好ましく、その配合量はビフェニル構造及びノボラック構造を有したエポキシ樹脂の配合量に対して０．２〜０．６重量％が最適である。０．２重量％未満では、はんだ耐熱性が十分ではなく、０．６重量％を超えると絶縁樹脂組成物の保存安定性やＢステージ状の絶縁樹脂組成物の取り扱い性が低下するためである。
【００２３】
（Ｅ）溶解性パラメータが７．５〜１０．５の溶剤はこの溶解性パラメータの範囲にあれば特に限定するものではないが、他の樹脂との溶解性を考慮すると、Ｐ−キシレン（溶解性パラメータ８．８）、メチルエチルケトン（溶解性パラメータ９．３）、ジエチルケトン（溶解性パラメータ８．８）、シクロヘキサノン（溶解性パラメータ９．９）、ジエチレングリコール（溶解性パラメータ９．２）、セロソルブアセテート（溶解性パラメータ９．３）等が好ましく、これらの溶剤は単独あるいは２種以上を混合しても良い。
【００２４】
絶縁樹脂組成物は、さらに（Ｆ）界面活性剤を含むのが好ましい。（Ｆ）界面活性剤は、絶縁剤用途に使用可能なものであれば特に制限はなく、例えばポリカルボン酸型界面活性剤のホモゲノールＬ−１８（花王株式会社製商品名）、Ｌ−１８２０（花王株式会社製商品名）、イミダゾリン型界面活性剤のホモゲノールＬ−９５（花王株式会社製商品名）が使用可能である。これらの界面活性剤は少量で分散性を高める効果があり、処理するリン含有フェノール樹脂量に対して１重量％以上であれば問題ない。
【００２５】
絶縁樹脂組成物は、さらに（Ｇ）無機フィラーを含むのが好ましい。無機フィラーは、例えばシリカ、溶融シリカ、タルク、アルミナ、水酸化アルミニウム、硫酸バリウム、水酸化カルシウム、エーロジル、炭酸カルシウムの中から選ばれるものが使用可能であり、これらは単独でもあるいは混合して用いても良い。なお、難燃性や低熱膨張の点から水酸化アルミニウムとシリカとを単独あるいは併用して用いるのが良い。またその配合量は、溶剤を除く絶縁樹脂組成物全体の固形分中で５〜３０ｖｏｌ％にするのが好ましい。さらに好ましくは、１０〜２０ｖｏｌ％であり、５ｖｏｌ％未満では外層回路導体との接着力が劣り、また３０ｖｏｌ％を超えると粗化後の表面粗さが大きくなることがあり微細粗化形状に不適になる。
これらの無機フィラーは、分散性を高める目的でカップリング剤で処理しても良く、ニーダー、ボールミル、ビーズミル、３本ロール等既知の混練方法により分散しても良い。
【００２６】
本発明の絶縁樹脂組成物の製造方法は、前記必須成分（Ａ）〜（Ｅ）のうち、予め（Ｅ）溶解性パラメータが７．５〜１０．５の範囲にある溶剤の少なくとも一部を含む液中に（Ｃ）リン含有フェノール樹脂を分散してリン含有フェノール樹脂の分散液を得る工程を含むことを特徴とする。
単に機械的な分散方法を用いることは絶縁樹脂に分散した後で分散不良やリン含有フェノール樹脂どうしの凝集を招くことから好ましくない。このため、本発明では、上記（Ａ）〜（Ｅ）等の各成分を絶縁樹脂組成物として配合する前に、（Ｃ）リン含有フェノール樹脂を、（Ｅ）溶解性パラメータが７．５〜１０．５の範囲にある溶剤の少なくとも一部を含む液中に予め分散させた分散液状態としたものを調製し、この分散液を絶縁樹脂組成物中に配合する。
上記製造方法において、前記分散液のための溶剤の少なくとも一部を含む液に、（Ｆ）界面活性剤を加えるのが好ましい。
【００２７】
本発明の絶縁樹脂組成物の製造方法の一例を挙げると、前記の（Ｅ）溶剤、好ましくは前記の溶剤と（Ｆ）界面活性剤との混合液に、（Ｃ）リン含有フェノール樹脂を少量ずつ加え、例えば７００ｒｐｍ付近の回転数で約１時間攪拌して分散液とする。前記分散液と残りの各成分とをビーズミル等で充分に撹拌した後、泡がなくなるまで静置して本発明の絶縁樹脂組成物が製造できる。上記撹拌後に濾過することも好ましい。予め分散液とすることにより、絶縁樹脂組成物を配合する際に、リン含有フェノール樹脂は１次粒子系の状態で凝集することなく絶縁樹脂組成物中へ分散することができる。
この分散液のリン含有フェノール樹脂の濃度は固形分で１０〜６０重量％の範囲にするのが好ましい。リン含有フェノール樹脂の濃度が固形分で１０重量％未満では、分散性に変わりはないが絶縁樹脂全体の溶剤量が増え、環境面やコスト面で好ましくない。また、リン含有フェノール樹脂の濃度が固形分で６０重量％を超えると溶液のチキソ性が高まり分散不良が起こりやすくなる。
【００２８】
本発明の絶縁樹脂組成物の成分には、前記必須成分の他、前記任意成分、さらに、通常の樹脂組成物に使用されるチキソ性付与剤、カップリング剤等の各種添加剤を適宜配合できる。
本発明の第一の絶縁樹脂組成物は、前記製造方法により製造された絶縁樹脂組成物である。本発明の第二の絶縁樹脂組成物は、上記（Ａ）〜（Ｅ）の必須成分を含むものである。
【００２９】
前記第二の絶縁樹脂組成物は、（Ｃ）リン含有フェノール樹脂として、（Ｅ）溶解性パラメータが７．５〜１０．５の範囲にある溶剤の少なくとも一部を含む液中に予めリン含有フェノール樹脂を分散した分散液を用いてなるのが好ましい。また、分散液に（Ｆ）界面活性剤が含まれるのが好ましい。
【００３０】
本発明の絶縁樹脂組成物は、溶剤中で混合して希釈または分散させてワニスの形態として使用するのが好ましい。この溶剤には、上記リン含有フェノール樹脂分散液に用いた（Ｅ）成分の溶剤のような制限は特になく、メチルエチルケトン、キシレン、トルエン、アセトン、エチレングリコールモノエチルエーテル、シクロヘキサノン、エチルエトキシプロピオネート、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド等を使用できる。また（Ｅ）成分と同一の溶剤を用いても良い。これらの溶剤は、単独あるいは混合系でも良い。この溶剤の前記樹脂組成物に対する割合は、従来使用している割合でよく、絶縁樹脂組成物の塗膜形成の設備にあわせてその使用量を調整する。
絶縁樹脂組成物をコンマコータでキャリアフィルムや銅箔に塗工する場合は、溶剤を除く樹脂組成物の固形分がワニス中３０〜６０重量％となるように溶剤の使用量を調節することが好ましい。
【００３１】
本発明の多層配線板は、内層回路を有する基板の片面または両面に絶縁層及び外層回路層が逐次積層されている。そして、絶縁層には、前記本発明の絶縁樹脂組成物が硬化してなる絶縁樹脂層が含まれることを特徴とする。前記絶縁樹脂組成物は多層配線板作製時の熱履歴により硬化される。
【００３２】
本発明の多層配線板の絶縁樹脂層の厚さは３０μｍ以下であるのが好ましい。また絶縁樹脂層の引っ張り伸び率は４％以上が好ましい。なお、引っ張り伸び率上限は、他の特性に支障が生じない限り、特に制限するものではない。４％よりも低いと機械的または熱的な応力集中に耐えられるような変形が少なくなるため、電子部品やそれを多層配線板と接続させるはんだや銅の熱的な応力集中により絶縁樹脂内部にクラックを発生しやすくなる傾向がある。
本発明の多層配線板における絶縁樹脂層の粗化処理後の表面粗さは、Ｒｚで１〜３であるのが好ましい。
なお、本発明における引っ張り伸び率とは、引張り試験機によって膜状の試料を一定速度で引張ったときに試料が伸びる割合、すなわち、例えば厚さ３０μｍの試料を１０ｍｍ×１００ｍｍの短冊状に切断し、長尺方向の両端１０ｍｍを固定して５ｍｍ／分の速度で引張った場合に、試料が切断されるまでに試料が伸びる割合を示す。
また、Ｒｚは、表面粗さの内、十点平均粗さ、すなわち対象物表面の抜き取り部分中で、最高から五番目までの山頂の平均線からの絶対値の平均値と、最低から五番目までの谷底の平均線からの絶対値の平均値との和を示すパラメータである（JIS B0601）。本発明では抜き取り部分１４９μｍからＲｚ（μｍ）を得た。
【００３３】
本発明の多層配線板は、次のような本発明の多層配線板の製造方法により製造することができる。
図１を参照して、前記本発明の絶縁樹脂組成物を用いて多層配線板を製造する工程を説明する。図１の（ａ）〜（ｉ）は多層配線板を製造する工程の一例を説明する断面図である。
まず、絶縁基板２上に第一の回路層１ａを形成した回路板３を用意する［図１（ａ）参照］。
回路板は、例えば、第一の回路層（内層配線）が表面に形成された内層基板であり、内層基板として、通常の配線板において用いられている公知の積層板、例えば、ガラス布−エポキシ樹脂、紙−フェノール樹脂、紙−エポキシ樹脂、ガラス布・ガラス紙−エポキシ樹脂等が使用でき特に制限はない。また、ビスマレイミド−トリアジン樹脂を含浸させたＢＴ基板、さらにはポリイミドフィルムを基材として用いたポリイミドフィルム基板等も用いることができる。
【００３４】
また、回路層１ａを形成するための方法についても特に制限はなく、銅箔と前記絶縁基板を張り合わせた銅張り積層板を用い、銅箔の不要な部分をエッチング除去するサブトラクティブ法や、前記絶縁基板の必要な個所に無電解めっきによって回路を形成するアディティブ法等、公知の配線板の製造方法を用いることができる。
また、図１（ａ）には絶縁基板２の片面に回路層１ａを形成した例を示すが、両面銅張積層板を用いて回路層１ａを絶縁基板２の両面に形成することもできる。
【００３５】
次に、必要に応じて回路層１ａの表面を接着性に適した状態に表面処理する。この手法も、特に制限はなく、例えば、次亜塩素酸ナトリウムのアルカリ水溶液により回路層１ａの表面に酸化銅の針状結晶を形成し、形成した酸化銅の針状結晶をジメチルアミンボラン水溶液に浸漬して還元するなど公知の製造方法を用いることができる。
【００３６】
（イ）そして、回路層１ａを有する回路板３の片面若しくは両面に本発明の絶縁樹脂組成物の層である絶縁樹脂組成物層４ｂを形成する［図１（ｂ）参照］。図１（ｂ）では、回路層１ａは回路板３の片面に形成されているが、両面に形成されていても良く、この場合は絶縁樹脂組成物層４ｂを回路板３の両面に形成できる。また、この形成方法に特に制限はない。例えば、絶縁樹脂組成物のワニスを前記のように作製し、このワニスを支持体上に塗布し、乾燥して支持体付き絶縁フィルムを作製し、これを回路板３に積層して形成する方法が挙げられる。また、直接回路層１ａを有する回路板３の片面若しくは両面にカーテンコートやロールコータを用いて塗工して層を形成する方法が挙げられる。
【００３７】
ワニスを回路板上に塗布する場合はバーコート、スピンコート、スクリーン印刷など一般の塗布方法が使用できる。また、ワニスを支持体上に塗布する場合はコンマコータ、バーコータ、キスコータ、ロールコータなどが利用でき、絶縁フィルムの厚みによって適宜使用される。何れの場合も塗布厚、塗布後の乾燥条件等は特に制限するものではないが、ワニスに使用した溶剤が８０重量％以上揮発していることが好ましい。
ワニスが塗布される支持体としては、ＰＥＴ等のプラスチックフィルムや金属箔等が挙げられ、ワニス硬化後に支持体を剥離除去する場合は離型性のプラスチックフィルム等が好ましい。また、支持体が銅箔等金属箔の場合は、剥離せずに後述する第二の回路層用として引き続き用いることができる。支持体付き絶縁フィルムの絶縁樹脂組成物層を回路板の回路層と接する面側に向け、ラミネート法やプレス装置を用いて回路板３に積層する。
【００３８】
（ロ）その後、絶縁樹脂組成物層を加熱硬化させて絶縁樹脂層である第一の絶縁層６ｃとするが［図１（ｃ）参照］、その硬化温度は後のめっき処理や銅のアニール処理などを考慮した温度や時間で行う。すなわち、あまり硬化を進めると後のめっき処理時に銅との接着性が低下したり、反面硬化が足りないとめっき処理時のアルカリ処理液に浸食されめっき液に溶解するような現象が生じたりする。これらのことを考慮すると、150〜190℃で30〜90分間の熱処理を与えて硬化するのが望ましい。
前記支持体付き絶縁フィルムを使用した場合は、加圧積層工程と加熱硬化工程とは同時でも別でもよい。加圧積層条件は、半硬化状態の絶縁樹脂組成物に回路層１ａの凹凸が埋め込まれれば良く、通常０．５〜２０ＭＰａが好ましい。
【００３９】
さらに、内層回路である第一の回路層１ａと外層回路を層間接続するために第一の絶縁層６ｃにビアホール５ｃを形成することもできる［図１（ｃ）参照］。このビアホールの形成手法として特に制限はなく、レーザ法やサンドブラスト法などを用いることができる。
【００４０】
（ハ）次に、以下のような回路加工を施すことにより第二の回路層１ｄを形成し、さらに第一の回路層１ａと第二の回路層１ｄとの層間接続を形成する［図１（ｄ）参照］。
まず、外層回路である第二の回路層１ｄをめっき法で形成する場合は、第一の絶縁層６ｃを粗化処理するのが好ましい。粗化液としては、クロム／硫酸粗化液、アルカリ過マンガン酸粗化液、フッ化ナトリウム／クロム／硫酸粗化液、ホウフッ酸粗化液などの酸化性粗化液を用いることができる。粗化処理としては、例えば、先ず膨潤液として、ジエチレングリコールモノブチルエーテルとＮａＯＨとの水溶液を７０℃に加温して第一の絶縁層６ｃを５分間浸漬処理する。次に、粗化液として、ＫＭｎＯとＮａＯＨとの水溶液を８０℃に加温して１０分間浸漬処理する。引き続き、中和液、例えば塩化第一錫（ＳｎＣｌ_２）の塩酸水溶液に室温で５分間浸漬処理して中和する。
【００４１】
粗化処理後、パラジウムを付着させるめっき触媒付与処理を行う。めっき触媒処理は、塩化パラジウム系のめっき触媒液に浸漬して行われる。
次に、無電解めっき液に浸漬して第一の絶縁層６ｃ表面全面（ビアホールを形成した場合はビアホール内面を含む）に厚さが０．３〜１．５μｍの無電解めっき層（導体層）を析出させる。必要により、更に電気めっきを行って必要な厚さとする。無電解めっきに使用する無電解めっき液は、公知の無電解めっき液を使用することができ、特に制限はない。また、電気めっきについても公知の方法によることができ特に制限はない。これらのメッキは銅メッキであることが好ましい。
さらに不要な箇所をエッチング除去して第二の回路層１ｄと第一の回路層１ａ及び第二の回路層１ｄの層間接続とを形成することができる。
【００４２】
また、絶縁樹脂組成物層の形成に銅箔付絶縁フィルムを用いた場合は、外層回路（第二の回路層１ｄ）をエッチング法を用いて形成する。このエッチング法を用いる手法に特に制限はなく、厚み３μｍ程度の極薄銅箔を用いてパターンめっき法も用いることができる。この銅箔付絶縁フィルムを用いた場合の層間接続は、レーザ法等の方法でビアホールを設けた後、メッキ等により形成できる。
なお、第二の回路層１ｄを形成するための手法としては、前記の粗化した絶縁層表面に無電解めっき用の触媒を付与して全面に無電解めっき銅を析出させ、必要な場合には電気めっきによって回路導体を必要な厚さにして、不要な箇所をエッチング除去して形成する方法の他に、めっき触媒を含有した絶縁層を用いて、めっきレジストを形成して必要な箇所のみ無電解めっきにより回路形成する方法、及びめっき触媒を含有しない絶縁層を粗化し、めっき触媒を付与した後めっきレジストを形成して必要な箇所のみ無電解めっきにより回路形成する方法等を用いることができる。
【００４３】
さらに、第一の回路層１ａの表面処理と同様にして第二の回路層１ｄの表面処理を行い、前記絶縁樹脂組成物層４ｂの形成と同様にして絶縁樹脂組成物層４ｅを形成する［図１（ｅ）参照］。次いで、絶縁樹脂組成物層４ｅを硬化させて第二の絶縁層６ｆとし、また、ビアホール５ｆを形成する［図１（ｆ）参照］。さらに、同様にして第三の回路層１ｇを形成する［図１（ｇ）参照］。
以下、更に同様の工程を繰り返して層数の多い多層配線板を製造できる。
【００４４】
【実施例】
次に実施例により本発明を説明するが、本発明はこれらの実施例に限定されるものではない。
（実施例１）
（１）ガラス布基材エポキシ樹脂両面銅張積層板［銅箔の厚さ１８μｍ、基板厚み０．８ｍｍt、両面粗化箔を両面に有する日立化成工業株式会社製ＭＣＬ−Ｅ−６７（商品名）］の片面にエッチングを施して片面に回路層（以下、第一の回路層とする。）を有する回路板を作製した。
【００４５】
（２）下記組成の絶縁樹脂組成物を容器内で配合し、この樹脂配合液全体をビーズミルを用いて約３０分間分散させ、その後３８０メッシュのナイロンメッシュで濾過して絶縁樹脂組成物のワニスを作製した。この時のエポキシに対する熱硬化剤の当量は１．０当量とした。この絶縁樹脂組成物のワニスをPETフィルム上に塗工し、１００℃−１０分乾燥して膜厚３０±３μｍの支持体付絶縁フィルムのロールを作製した。さらに、この支持体付絶縁フィルムと前記回路板を、絶縁樹脂組成物層を回路板の回路層と接する面側にしてバッチ式真空加圧ラミネーターＭＶＬＰ−５００（名機株式会社製、商品名）を用いて積層した。
【００４６】
［組成］
・（Ａ）ビフェニル構造及びノボラック構造を有したエポキシ樹脂：ＮＣ３０００Ｓ−Ｈ
(日本化薬株式会社社製、商品名) ８２重量部
・（Ｂ）カルボン酸変性アクリロニトリルブタジエンゴム（線状NBR）のＰＮＲ−１Ｈ (ＪＳＲ株式会社製、商品名)と粒子状NBRのXER-91 (ＪＳＲ株式会社、商品名)を固形分比で１対１で混合した混合物１２重量部
・（Ｃ）リン含有フェノール樹脂：ＨＣＡ−ＨＱ（三光株式会社製、商品名）
メチルエチルケトン中に上記リン含有フェノール樹脂の固形分濃度として３０重量％となる（Ｅ）メチルエチルケトンを準備し、さらにリン含有フェノール樹脂量の１．５重量％となるポリカルボン酸型の（Ｆ）界面活性剤のＬ−１８２０（花王株式会社製商品名）を準備した。これら準備したメチルエチルケトンとポリカルボン酸型界面活性剤とをスリーワン攪拌機で回転数７００ｒｐｍで攪拌しておき、その中へリン含有フェノール樹脂を少量づつ加えながら約１時間攪拌して分散液を得た。このリン含有フェノール樹脂分散液を使用した。なお、表１では「先混合」と表す。

【００４７】
（３）次に、ＰＥＴフィルムを剥がした後、１８０℃―６０分の硬化条件で前記絶縁樹脂組成物層を硬化して第一の絶縁層を得た。
（４）この第一の絶縁層に層間接続用のビアホールを日立ビアメカニクス製ＣＯ_２レーザ加工機（ＬＣＯ−１Ｂ２１型）を使用し、ビーム径８０μｍ、周波数５００Ｈｚでパルス幅５μｓｅｃ、ショット数７の条件で加工して作製した。
【００４８】
（５）第一の絶縁層を化学粗化するために、膨潤液として、ジエチレングリコールモノブチルエーテル：２００ｍｌ／L、ＮａＯＨ：５ｇ／Lの水溶液を作製し、７０℃に加温して５分間浸漬処理した。次に、粗化液として、ＫＭｎＯ_４：６０ｇ／L、ＮａＯＨ：４０ｇ／Lの水溶液を作製し、８０℃に加温して１０分間浸漬処理した。引き続き、中和液（ＳｎＣｌ_２：３０ｇ／L、ＨＣｌ：３００ｍｌ／L）の水溶液に室温で５分間浸漬処理して中和した。
【００４９】
（６）第一の絶縁層表面に第二の回路層を形成するために、まず、ＰｄＣｌ_２を含む無電解めっき用触媒であるＨＳ−２０２Ｂ（日立化成工業株式会社製、商品名）に、室温−１０分間浸漬処理し、水洗し、無電解銅めっき用であるめっき液CUST-201（日立化成工業株式会社製、商品名）に室温−１５分間浸漬し、さらに硫酸銅電解めっきを行った。その後、アニールを１８０℃−３０分間行い第一の絶縁層表面およびビアホール内に厚さ２０μｍの導体層を形成した。
次に、めっき導体の不要な箇所をエッチング除去するために、まず銅表面の酸化皮膜を＃６００のバフロール研磨で除去した後、エッチングレジストを形成し、次いでエッチングし、その後エッチングレジストを除去して、第一の回路層と接続したバイアホールを含む第二の回路形成を行った。
【００５０】
（７）さらに、多層化するために、第二の回路導体表面を、亜塩素酸ナトリウム：５０ｇ／ｌ、ＮａＯＨ：２０ｇ／ｌ、リン酸三ナトリウム：１０ｇ／ｌの水溶液に８５℃−２０分間浸漬し、水洗して、８０℃−２０分間乾燥して第二の回路導体表面上に酸化銅の凹凸を形成した。
（８）前記（２）〜（７）の工程を繰り返して三層の多層配線板を作製した。
【００５１】
（実施例２）
実施例１において、無機フィラーを水酸化アルミニウムを用いずに球状シリカ（アドマファインＳＯ−２５Ｒ）単独とし、配合量を３２重量部とした。その他は実施例１と同様にして行った。
【００５２】
（実施例３）
実施例１において、支持体付絶縁フィルムを作製して該フィルムを第一の回路層に積層する代わりに、絶縁樹脂組成物のワニスを直接、回路板の第一の回路層を有する面側にロールコータにより塗布し、１１０℃で１０分間乾燥して膜厚３０±４μｍの絶縁樹脂組成物層を形成した。その他は、実施例１と同様にして行った。
【００５３】
（実施例４）
実施例１において、メチルエチルケトンの代わりに、メチルエチルケトンとシクロヘキサノンの１対１の混合溶剤を用いて、さらに界面活性剤をイミダゾリン型界面活性剤のホモゲノールＬ−９５（花王株式会社製商品名）に変更した。その他は、実施例１と同様にして行った。
【００５４】
（実施例５）
実施例１において、界面活性剤を使用しなかった以外は、実施例１と同様にして行った。
（実施例６）
実施例１において、リン含有フェノール樹脂分散液を調製せず、リン含有フェノール樹脂、メチルエチルケトン及び界面活性剤を他の成分と同時に容器内で配合した以外は、実施例１と同様にして行った。
（実施例７）
実施例６において、界面活性剤を使用しなかった以外は、実施例６と同様にして行った。
【００５５】
（比較例１）
実施例１において、メチルエチルケトンの代わりに、ジメチルホルムアミド（溶解性パラメータ１２．１）に変更した。その他は、実施例１と同様にして行った。
【００５６】
（比較例２）
実施例１において、リン含有フェノール樹脂をメチルエチルケトンを用いずに粉末状態で使用した。その他は実施例１と同様にして行った。
（比較例３）
実施例１において、リン含有フェノール樹脂をメチルエチルケトンと界面活性剤を用いずに粉末状態で使用した。その他は実施例１と同様にして行った。
（比較例４）
実施例１において、メチルエチルケトンの代わりに、ジエチルエーテル（溶解性パラメータ７．４）に変更した。その他は、実施例１と同様にして行ったところ、ワニスが分離して塗布できないため評価できなかった。
【００５７】
以上のようにして作製した樹脂組成物のワニス及び多層配線板について、▲１▼難燃性、▲２▼絶縁樹脂塗膜の引っ張り伸び率、▲３▼絶縁樹脂の粗化後の表面粗さ、▲４▼外層回路との接着強度、▲５▼絶縁樹脂の冷熱サイクル試験下でのクラック発生率、▲６▼不飽和雰囲気下での絶縁信頼性加速試験、▲７▼２８８℃はんだ耐熱性試験を実施した。その結果を表１に示す。
【００５８】
［難燃性］
各実施例及び比較例において内層の回路板として用いた、前記ガラス布基材エポキシ樹脂両面銅張積層板にエッチングを施して銅箔を完全に剥離した基板を作製し、この基板の両面に、片側の絶縁樹脂厚１５０μｍとなるように前記ワニスを塗布して絶縁樹脂組成物層を形成した。そして、１８０℃-１時間後加熱を行うことにより、難燃性の試験片を作製した。
試験法は、ＵＬ−９４法に従い試験した。
【００５９】
［塗膜の引っ張り伸び率］
各実施例及び比較例におけるワニスを銅箔に塗工し、配線板作製と同様の１８０℃―６０分の熱処理を加えて硬化した。そして、銅をエッチング除去して硬化した絶縁樹脂塗膜を得た。この絶縁樹脂塗膜を厚さ３０μｍ、幅１０ｍｍ、長さ１００ｍｍに切断し、引張り速度約５ｍｍ／分でオートグラフ引っ張り試験（チャック間距離５０ｍｍ）により、絶縁樹脂塗膜を引っ張り、破断するまでの引っ張り伸び率を求めた。
【００６０】
［粗化後の表面粗さ：Ｒｚ］
各実施例及び比較例で得た多層配線板の外層回路をエッチングにより銅を除去した試験片を作製した。この試験片を２ｍｍ角程度に切断した。キーエンス社製超深度形状測定顕微鏡製品名ＶＫ−８５００を用いて、試験片表面から測定長さ１４９μｍを選択し、倍率２０００倍、分解能０．０５μｍの条件で観察し、１４９μｍ中の十点平均粗さ（Ｒｚ）を算出した。
【００６１】
［外層回路との接着強度］
各実施例及び比較例で得た多層配線板のＬ１回路層（第三の回路層）の一部に幅１０ｍｍ、長さ１００ｍｍの部分を形成し、この一端を回路層／樹脂界面で剥がしてつかみ具でつかみ、垂直方向に引張り速度約５０ｍｍ／分で室温中で引き剥がした時の荷重を測定した。
【００６２】
［絶縁樹脂の冷熱サイクル試験下でのクラック発生率］
内層の回路板に用いた日立化成工業株式会社製ＭＣＬ−Ｅ−６７（基板厚み０．８ｍｍt、商品名）の銅箔を完全にエッチングにより溶解、除去した。この片面上に各実施例及び比較例で得たワニスを、厚み３０±５μｍで塗膜成形した。この絶縁樹脂付き基板を実施例と同様に処理し、絶縁樹脂上に外層回路を形成した。そして外層回路が２ｍｍ角に残るパターンを形成するために銅面上にエッチングレジスト（Ｈ−Ｋ４２５、日立化成工業株式会社製、商品名）を１００℃、０．５ｍ／分、圧力０．５ＭＰａ・sの条件でラミネートした。その後、露光量８０ｍＪ／ｃｍ²で外層回路が２ｍｍ角に残るように作製されたフォトマスクを介して露光した。次いで、炭酸ナトリウム１．０％水溶液の現像液を用いて、３０℃、圧力０．１ＭＰａ・s、現像時間６０秒で現像し、さらに水酸化ナトリウム水溶液でレジストを剥離し、乾燥した。そして、塩化第二鉄水溶液で銅をエッチングして外層回路が２ｍｍ角となる耐クラック性評価パターンを作製した。
この試料を、−５５℃〜１２５℃（各１５分）の冷熱サイクル試験を実施し、顕微鏡で外層回路の２ｍｍ角コーナー部に発生しやすい絶縁樹脂中のクラックを観察し、クラックが入るまでのサイクル試験回数で表した。
【００６３】
［不飽和雰囲気下での絶縁信頼性加速試験］
各実施例及び比較例で作製した多層配線板において、絶縁樹脂の層間方向に電圧印加できるように端子部にリード線をはんだ付けで固定した。そして、絶縁樹脂の層間方向の絶縁抵抗を室温中で50Ｖ、１分印加して測定した。さらに、これを試料とし、１３０℃、８５％ＲＨの不飽和雰囲気下で直流電圧１０Vを印加しながら所定時間で試料を取り出し、室温中で50Ｖ、１分印加して測定した時の１０^８Ω以上を示す時間を絶縁信頼性の時間として表した。
【００６４】
［２８８℃はんだ耐熱性］
各実施例及び比較例で作製した多層配線板を25ｍｍ角に切断し、２８８℃±２℃に調整したはんだ浴に浮かべ、ふくれが発生するまでの時間を調べた。
【００６５】
【表１】

【００６６】
表１から、本発明の絶縁樹脂組成物を用いた多層配線板の特性は、実施例１〜７に示したように、難燃性に優れ、また約３０μｍ前後と非常に膜厚が薄い状態でも高い絶縁信頼性を有し、さらに塗膜の伸び率が大きいために耐クラック性に良好な結果を示す。さらに、粗化後の表面粗さが小さいながら外層銅との接着強度が良好であり微細配線化に適しており、絶縁信頼性、288℃はんだ耐熱性にも優れており環境に配慮した多層配線板を製造することが可能である。
一方、本発明の絶縁樹脂組成物を必須に含んでいない比較例１〜３に示す多層配線板は、絶縁信頼性が極端に悪くなりはんだ耐熱性の低下も引き起こす傾向を確認できた。
【００６７】
【発明の効果】
本発明によれば、環境に悪影響を与える可能性があるブロム化合物を一切使用しないで難燃性を有し、また３０μｍと非常に膜厚が薄い状態でも高い絶縁信頼性を得る絶縁樹脂組成物を提供できる。さらに鉛フリー化に対応可能な高いはんだ耐熱性と機械的や熱的な応力集中に耐えられるような絶縁樹脂塗膜の高引っ張り伸び率を実現させ、さらに接着強度を維持して粗化後の表面粗さＲｚを１〜３μｍの範囲内にして微細配線化に対応可能な特性に優れた多層配線板を提供できる。
【図面の簡単な説明】
【図１】（ａ）〜（ｉ）は多層配線板を製造する工程の一例を説明する断面図である。
【符号の説明】
１ａ第一の回路層
１ｄ第二の回路層
１ｇ第三の回路層
２絶縁基板
３回路板
４ｂ、４ｅ絶縁材料組成物層
５ｃ、５ｆビアホール
６ｃ第一の絶縁層
６ｆ第二の絶縁層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an insulating resin composition, an insulating resin composition, a multilayer wiring board, and a method for producing the same.
[0002]
[Prior art]
To manufacture a multilayer wiring board, a material made by impregnating a glass cloth called prepreg with epoxy resin into a semi-cured state is laminated with copper foil on an insulating substrate with an inner layer circuit formed on one or both sides, and laminated by hot pressing. After integration, a hole called a through hole for interlayer connection is drilled with a drill, electroless plating is performed on the inner wall of the through hole and the copper foil surface, and if necessary, further electrolytic plating is performed to obtain a necessary thickness as a circuit conductor. After that, it was common to produce a multilayer wiring board by removing unnecessary copper.
By the way, in recent years, electronic devices have been further reduced in size, weight and functionality, and along with this, LSIs and chip parts have been highly integrated, and their form has rapidly changed to multi-pin and miniaturization. ing. For this reason, in order to improve the mounting density of electronic components, multilayer wiring boards are being developed for fine wiring. As a manufacturing method of multilayer wiring boards that meet these requirements, a build-up multilayer that uses insulating resin that does not contain glass cloth as an insulating layer instead of prepreg, and forms wiring layers while connecting only necessary parts with via holes. There is a wiring board, and it is becoming mainstream as a technique suitable for weight reduction, miniaturization, and miniaturization.
[0003]
In addition, there is an active movement to regulate materials including electronic parts that may generate harmful substances during combustion due to increased environmental awareness. In conventional multilayer wiring boards, bromine compounds that may generate harmful substances during combustion have been used for flame retardancy, but it is expected that their use will be difficult in the near future.
Furthermore, a lead-free solder that does not have lead as a solder generally used for connecting an electronic component to a multilayer wiring board is being put into practical use. This lead-free solder has a use temperature higher than that of a conventional eutectic solder by about 20 to 30 ° C. Therefore, the material is required to have higher solder heat resistance than ever before.
[0004]
As described above, the items required for the multilayer wiring board become stricter year by year. In particular, the insulating layer having an important role for connecting the substrate and the circuit needs to have higher performance.
However, since the insulating resin layer that does not include glass cloth for reducing the thickness of the multilayer wiring board does not include glass cloth, the mechanical properties of the insulating resin greatly affect the characteristics of the multilayer wiring board. Specifically, when the insulating resin is hard and its elongation is small and brittle, mechanical stress at the time of punching the multilayer wiring board into the product size causes cracking or chipping in the insulating resin, resulting in large conduction or insulation reliability. It will be a hindrance. In addition, in order to achieve downsizing and multi-functionality of equipment, electronic components are shifted to surface mount type, so the distance between insulating resin and electronic components is narrowed, and thermal stress of electronic components is concentrated on insulating resin. It has become easier to do. In other words, if the insulating resin is hard and its elongation is small and fragile, cracks are likely to occur inside the insulating resin and in the solder and copper due to the thermal stress concentration of the solder and copper that connects the electronic component and the multilayer wiring board. I will let you.
For this reason, the insulating resin has been required to have a property that can withstand mechanical and thermal stress concentration, that is, a property having a high tensile elongation.
[0005]
[Problems to be solved by the invention]
However, as a technique for increasing the tensile elongation rate, a technique of introducing a thermoplastic high molecular weight component is generally used. However, when a high molecular weight component is introduced, a decrease in glass transition point is generally unavoidable.
Moreover, the fact is that an insulating resin having high insulation reliability without using a bromo compound so as not to affect the environment has not been developed at this stage. The reason is that in order to obtain high flame retardancy and solder heat resistance, it is necessary to use a filler-type flame retardant, but generally a filler-type flame retardant is difficult to dissolve in a solvent and its dispersibility deteriorates. That is, if the dispersibility is poor, it is easy to generate a grain boundary that allows electricity to flow through the insulating layer, or the insulating distance is likely to be reduced due to partial loss of the flame retardant.
Furthermore, miniaturization and higher functionality of electronic devices are progressing, and miniaturization of wiring boards is progressing. In order to achieve fine wiring, it is necessary to reduce the roughness of the interface between the insulating resin and the circuit conductor as much as possible from the viewpoint of the etching accuracy of the circuit conductor. For this reason, recently, a low-roughened foil whose surface roughness Rz after roughening of the copper foil is from 7 to 8 μm to 3 to 4 μm has been put into practical use from a copper foil manufacturer. However, the roughness of the interface between the insulating resin and the circuit conductor has an important influence on the bonding strength between the insulating resin and the circuit conductor, and the bonding strength decreases as the interface roughness decreases. Therefore, there is a need for an insulating resin that can exhibit high adhesive strength even with low roughness.
[0006]
The present invention has flame retardancy without using any bromine compound that may adversely affect the environment, further improves insulation by eliminating poor dispersion of the flame retardant, and is highly compatible with lead-free Uses insulating resin with low roughness after roughening to achieve high elongation of the insulating resin coating that can withstand solder heat resistance and mechanical and thermal stress concentration, and to accommodate fine wiring. An object of the present invention is to provide a method for manufacturing a multilayer wiring board.
[0007]
[Means for Solving the Problems]
As a result of researches to solve such problems, the present inventors have found that an insulating layer in a multilayer wiring board is an insulating resin having a biphenyl structure and a novolak structure, an acrylonitrile butadiene copolymer and a phosphorous resin. Do not use any bromine compounds that may adversely affect the environment by using insulating resins that contain the contained phenolic resin and thermosetting agent as essential components, and further eliminating the poor dispersion of flame retardants to improve insulation. It has flame resistance and high solder heat resistance that is compatible with lead-free and high elongation of insulating resin coating that can withstand mechanical and thermal stress concentration. It was possible to find an insulating resin composition having excellent insulation reliability.
[0008]
That is, the present invention comprises (1) (A) an epoxy resin having a biphenyl structure and a novolac structure, (B) an acrylonitrile butadiene copolymer, (C) a phosphorus-containing phenol resin, and (D) a thermosetting agent. (E) a method for producing an insulating resin composition comprising a solvent having a solubility parameter in the range of 7.5 to 10.5,
(E) A step of (P) dispersing a phosphorus-containing phenol resin in a liquid containing at least a part of a solvent having a solubility parameter in the range of 7.5 to 10.5 to obtain a phosphorus-containing phenol resin dispersion. It is related with the manufacturing method of the insulating resin composition characterized by including.
[0009]
Moreover, this invention relates to the manufacturing method of the insulating resin composition as described in said (1) which adds (F) surfactant to the liquid containing at least one part of the said solvent in the process of (2) obtaining a dispersion liquid.
The present invention relates to (3) the method for producing an insulating resin composition according to (1) or (2), wherein the concentration of the phosphorus-containing phenol resin in the dispersion is in the range of 10 to 60% by weight in terms of solid content.
[0010]
The present invention also relates to (4) an insulating resin composition produced by the production method according to any one of (1) to (3).
[0011]
Furthermore, the present invention provides (5) (A) an epoxy resin having a biphenyl structure and a novolac structure, (B) an acrylonitrile butadiene copolymer, (C) a phosphorus-containing phenol resin, and (D) a thermosetting agent. And (E) an insulating resin composition comprising a solvent having a solubility parameter in the range of 7.5 to 10.5.
The present invention relates to (6) the insulating resin composition according to (5), further comprising (F) a surfactant.
The present invention provides (7) (E) a dispersion obtained by previously dispersing (C) a phosphorus-containing phenol resin in a liquid containing at least a part of a solvent having a solubility parameter in the range of 7.5 to 10.5. It is related with the insulating resin composition of the said (5) or (6) used.
The present invention relates to (8) the insulating resin composition according to (7), wherein the dispersion contains (F) a surfactant.
The present invention relates to (9) the insulating resin composition according to (7) or (8), wherein the concentration of the phosphorus-containing phenol resin in the dispersion is in the range of 10 to 60% by weight in terms of solid content.
[0012]
In the present invention, (10) (A) the epoxy resin having a biphenyl structure and a novolac structure is 35 to 60% by weight in the total solid content of the insulating resin composition, and (A) the epoxy resin (B) It is related with the insulating resin composition in any one of said (4)-(9) whose solid content compounding ratio with an acrylonitrile butadiene copolymer is 80 / 20-95 / 5 by weight ratio.
The present invention includes (11) further containing (G) an inorganic filler, and (C) a phosphorus content in the phosphorus-containing phenol resin is 0.7 to 3 in the solid content of the insulating resin composition excluding the (G) inorganic filler. It is related with the insulating resin composition in any one of (4)-(10) which is 0.0 weight%.
[0013]
The present invention is also (12) a multilayer wiring board in which an insulating layer and an outer layer circuit layer are sequentially laminated on one side or both sides of a substrate having an inner layer circuit, wherein the insulating layer is formed of (4) to (11). The present invention relates to a multilayer wiring board comprising an insulating resin layer formed by curing any of the insulating resin compositions.
[0014]
The present invention relates to (13) the multilayer wiring board according to (12), wherein the insulating resin layer has a thickness of 30 μm or less.
The present invention relates to (14) the multilayer wiring board according to (12) or (13), wherein the tensile elongation percentage of the insulating resin layer is 4% or more.
The present invention relates to (15) the multilayer wiring board according to any one of (12) to (14), wherein the surface roughness of the interface between the insulating resin layer and the outer circuit layer is 1 to 3 in Rz.
[0015]
Furthermore, the present invention provides (16) a step (a) of laminating an insulating layer containing a layer of the insulating resin composition according to any one of (4) to (11) above on a substrate having an inner layer circuit, the insulating resin composition The present invention relates to a method for manufacturing a multilayer wiring board, including a step (b) of obtaining an insulating resin layer by curing and a step (c) of forming an outer circuit layer on the surface of the insulating layer.
[0016]
The present invention includes (17) the method for producing a multilayer wiring board according to (16), wherein the step (b) includes a step of roughening the surface of the insulating resin layer with an oxidizing roughening solution after obtaining the insulating resin layer. About.
The present invention relates to (18) the method for producing a multilayer wiring board according to (16) or (17), wherein in the step (c), an outer layer circuit is formed by copper plating.
In the present invention, (19) in the step (a), a varnish of an insulating resin composition is applied to a support and dried to produce a film with a support. The insulating film with a support is formed on a substrate having an inner layer circuit. The multilayer wiring board according to any one of (16) to (18), which is laminated on the substrate.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
First, each component used for the insulating resin composition of the present invention and the manufacturing method thereof will be described.
(A) An epoxy resin having a biphenyl structure and a novolak structure is an epoxy resin having a novolak structure containing an aromatic ring of a biphenyl derivative in the molecule, and NC-3000S (trade name) manufactured by Nippon Kayaku Co., Ltd. And NC-3000S-H (trade name) can be used.
[0018]
The blending amount of the epoxy resin having (A) biphenyl structure and novolak structure is preferably 35 to 60% by weight in the total solid content of the insulating resin composition excluding the solvent, and (A) biphenyl. It is preferable that the solid content blending ratio (weight ratio, the same shall apply hereinafter) of the epoxy resin having the structure and the novolak structure and the (B) acrylonitrile butadiene copolymer is 80/20 to 95/5. When the blending amount of the component (A) is less than 35% by weight, the solder heat resistance is lowered, and when it exceeds 60% by weight, the adhesive strength with the circuit conductor tends to be lowered. Further, in the solid content blending ratio of the component (A) and the component (B), the solder heat resistance is deteriorated when the component (A) is decreased from 80/20, and conversely the component (B) is more than 95/5. When it increases, there exists a tendency for the tensile elongation rate of a coating film to fall.
[0019]
Examples of the (B) acrylonitrile butadiene copolymer include NBR obtained by copolymerization of acrylonitrile and butadiene, and those obtained by copolymerization of acrylonitrile, butadiene and carboxylic acid such as acrylic acid can also be used. These are preferably two types of mixtures of linear NBR obtained without crosslinking at the stage of copolymerization and partially crosslinked particulate NBR. In the case of this mixture, the blending ratio is good in terms of all the characteristics in the same solid content ratio. For example, in the case of a mixture obtained by copolymerizing acrylonitrile, butadiene and carboxylic acid, linear NBR and particulate form are used. A compounding ratio with NBR of 3/7 to 8/2 can be suitably used. In this case, when the linear NBR is less than 3/7 in the blending ratio, the coating film after applying the insulating resin and drying is uneven, and conversely, when it exceeds 8/2, the roughness after roughening increases. There is a tendency to become unsuitable for fine roughening shapes.
[0020]
(C) The phosphorus-containing phenol resin is obtained by reacting a bifunctional phenol resin and an organic phosphorus compound. For example, HCA-HQ (trade name) manufactured by Sanko Co., Ltd. can be used. The phosphorus content is preferably in the range of 0.7 to 3% by weight in the solid content of the insulating resin composition excluding the inorganic filler described later in order to exhibit flame retardancy. This is because if the phosphorus content is less than 0.7%, the flame retardancy is insufficient, and if the phosphorus content exceeds 3%, the solder heat resistance is lowered. As the phosphorus-containing phenol resin, it is preferable to use a resin having an average particle diameter of about 2 μm and a maximum particle diameter of about 6 μm or less from the viewpoint of insulation reliability.
[0021]
(D) The thermosetting agent is used for promoting the reaction between the epoxy group in the epoxy resin having a biphenyl structure and a novolak structure and the epoxy group in the epoxy resin having a biphenyl structure and a novolak structure and the phosphorus-containing phenol resin. The As the thermosetting agent, various phenol resins, acid anhydrides, amines, hydragits and the like can be used. As polyfunctional phenols, hydroquinone, resorcinol, bisphenol A and their halogen compounds, and novolak type phenol resins and resol type phenol resins which are condensates with formaldehyde can be used. Acid anhydrides include phthalic anhydride. Acid, benzophenone tetracarboxylic dianhydride, methyl hymic acid and the like can be used, and dicyandiamide, diaminodiphenylmethane, guanylurea and the like can be used as amines. Dicyandiamide is preferable from the viewpoint of adhesiveness to the circuit conductor, and it is more preferable to use dicyandiamide and novolak phenol in consideration of heat resistance and insulation.
These thermosetting agents are preferably 0.5 to 1.5 equivalents relative to the epoxy group. When the thermosetting agent is less than 0.5 equivalent with respect to the epoxy group, the adhesiveness with the outer layer copper is lowered, and when it exceeds 1.5 equivalent, Tg and insulation may be lowered.
[0022]
In addition to the thermosetting agent, a reaction accelerator can be used as necessary. As reaction accelerators, various imidazoles, which are latent thermosetting agents, and BF _Three Amine complexes can be used. More preferably, 2-phenylimidazole or 2-ethyl-4-methylimidazole is used from the viewpoint of storage stability of the insulating resin composition, handling property of the B-staged (semi-cured) insulating resin composition, and solder heat resistance. Preferably, the blending amount is optimally 0.2 to 0.6% by weight based on the blending amount of the epoxy resin having a biphenyl structure and a novolak structure. If it is less than 0.2% by weight, the heat resistance of the solder is not sufficient, and if it exceeds 0.6% by weight, the storage stability of the insulating resin composition and the handleability of the B-staged insulating resin composition are lowered. .
[0023]
(E) A solvent having a solubility parameter of 7.5 to 10.5 is not particularly limited as long as it is within the range of the solubility parameter. However, in consideration of solubility with other resins, P-xylene (dissolution Solubility parameter 8.8), methyl ethyl ketone (solubility parameter 9.3), diethyl ketone (solubility parameter 8.8), cyclohexanone (solubility parameter 9.9), diethylene glycol (solubility parameter 9.2), cellosolve acetate (Solubility parameter 9.3) is preferable, and these solvents may be used alone or in combination of two or more.
[0024]
The insulating resin composition preferably further contains (F) a surfactant. The surfactant (F) is not particularly limited as long as it can be used for an insulating agent. For example, homogenol L-18 (trade name, manufactured by Kao Corporation), L-1820 (polycarboxylic acid type surfactant) Kago Co., Ltd. product name) and imidazoline type surfactant homogenol L-95 (Kao Co., Ltd. product name) can be used. These surfactants have an effect of improving dispersibility even in a small amount, and there is no problem as long as it is 1% by weight or more based on the amount of the phosphorus-containing phenol resin to be treated.
[0025]
The insulating resin composition preferably further contains (G) an inorganic filler. The inorganic filler can be selected from, for example, silica, fused silica, talc, alumina, aluminum hydroxide, barium sulfate, calcium hydroxide, aerosil, and calcium carbonate, and these can be used alone or in combination. May be. From the viewpoint of flame retardancy and low thermal expansion, aluminum hydroxide and silica are preferably used alone or in combination. Moreover, it is preferable to make the compounding quantity into 5-30 vol% in solid content of the whole insulating resin composition except a solvent. More preferably, it is 10 to 20 vol%, and if it is less than 5 vol%, the adhesive strength with the outer layer circuit conductor is inferior, and if it exceeds 30 vol%, the surface roughness after roughening may increase and is not suitable for a finely roughened shape. become.
These inorganic fillers may be treated with a coupling agent for the purpose of enhancing dispersibility, or may be dispersed by a known kneading method such as a kneader, ball mill, bead mill, or three rolls.
[0026]
In the method for producing an insulating resin composition of the present invention, among the essential components (A) to (E), at least part of the solvent having a solubility parameter (E) in the range of 7.5 to 10.5 in advance is included. And (C) a step of dispersing the phosphorus-containing phenol resin in the liquid to contain to obtain a dispersion of the phosphorus-containing phenol resin.
It is not preferable to simply use a mechanical dispersion method because it causes poor dispersion or aggregation of phosphorus-containing phenol resins after being dispersed in the insulating resin. For this reason, in this invention, before mix | blending each component of said (A)-(E) etc. as an insulating resin composition, (E) solubility parameter is 7.5- A dispersion that has been dispersed in advance in a liquid containing at least a part of the solvent in the range of 10.5 is prepared, and this dispersion is blended in the insulating resin composition.
In the said manufacturing method, it is preferable to add (F) surfactant to the liquid containing at least one part of the solvent for the said dispersion liquid.
[0027]
An example of the method for producing the insulating resin composition of the present invention is as follows. A small amount of (C) phosphorus-containing phenol resin is added to the above-mentioned solvent (E), preferably a mixed solution of the above-mentioned solvent and (F) surfactant. For example, the mixture is stirred for about 1 hour at a rotation speed of about 700 rpm to obtain a dispersion. The dispersion and the remaining components are sufficiently stirred with a bead mill or the like, and then allowed to stand until there are no bubbles, whereby the insulating resin composition of the present invention can be produced. It is also preferable to filter after the stirring. By preparing the dispersion liquid in advance, when the insulating resin composition is blended, the phosphorus-containing phenol resin can be dispersed in the insulating resin composition without agglomerating in the primary particle system state.
The concentration of the phosphorus-containing phenol resin in this dispersion is preferably in the range of 10 to 60% by weight in terms of solid content. If the concentration of the phosphorus-containing phenol resin is less than 10% by weight in terms of solid content, the dispersibility is not changed, but the amount of solvent in the entire insulating resin increases, which is not preferable in terms of environment and cost. On the other hand, when the concentration of the phosphorus-containing phenol resin exceeds 60% by weight in terms of solid content, the thixotropy of the solution is increased and dispersion failure tends to occur.
[0028]
In addition to the above-mentioned essential components, various components such as a thixotropic agent and a coupling agent used in ordinary resin compositions can be appropriately added to the components of the insulating resin composition of the present invention. .
The first insulating resin composition of the present invention is an insulating resin composition produced by the production method. The 2nd insulating resin composition of this invention contains the essential component of said (A)-(E).
[0029]
The second insulating resin composition includes (C) a phosphorus-containing phenol resin, and (E) a phosphorus-containing material in advance in a liquid containing at least a part of a solvent having a solubility parameter in the range of 7.5 to 10.5. It is preferable to use a dispersion in which a phenol resin is dispersed. Moreover, it is preferable that (F) surfactant is contained in a dispersion liquid.
[0030]
The insulating resin composition of the present invention is preferably used in the form of a varnish after being mixed and diluted or dispersed in a solvent. This solvent is not particularly limited as the solvent of the component (E) used in the phosphorus-containing phenol resin dispersion, and methyl ethyl ketone, xylene, toluene, acetone, ethylene glycol monoethyl ether, cyclohexanone, ethyl ethoxypropionate. N, N-dimethylformamide, N, N-dimethylacetamide and the like can be used. Further, the same solvent as the component (E) may be used. These solvents may be used alone or in a mixed system. The ratio of the solvent to the resin composition may be a ratio that has been used conventionally, and the amount of the solvent used is adjusted in accordance with the equipment for forming the coating film of the insulating resin composition.
When coating the insulating resin composition on a carrier film or copper foil with a comma coater, it is preferable to adjust the amount of the solvent used so that the solid content of the resin composition excluding the solvent is 30 to 60% by weight in the varnish. .
[0031]
In the multilayer wiring board of the present invention, an insulating layer and an outer layer circuit layer are sequentially laminated on one side or both sides of a substrate having an inner layer circuit. The insulating layer includes an insulating resin layer formed by curing the insulating resin composition of the present invention. The insulating resin composition is cured by a thermal history during the production of the multilayer wiring board.
[0032]
The thickness of the insulating resin layer of the multilayer wiring board of the present invention is preferably 30 μm or less. The tensile elongation of the insulating resin layer is preferably 4% or more. The upper limit of tensile elongation is not particularly limited as long as other characteristics are not hindered. If it is lower than 4%, deformation that can withstand mechanical or thermal stress concentration is reduced. Therefore, the thermal stress concentration of the solder and copper that connects the electronic component and the multilayer wiring board causes the internal stress in the insulating resin. There is a tendency to easily generate cracks.
The surface roughness after the roughening treatment of the insulating resin layer in the multilayer wiring board of the present invention is preferably 1 to 3 in terms of Rz.
The tensile elongation in the present invention is the rate at which a sample is stretched when it is pulled at a constant speed by a tensile tester, that is, for example, a 30 μm thick sample is cut into a 10 mm × 100 mm strip. When the both ends 10 mm in the longitudinal direction are fixed and pulled at a speed of 5 mm / min, the rate at which the sample extends before being cut is shown.
In addition, Rz is the ten-point average roughness of the surface roughness, that is, the average value of the absolute values from the average line of the peak from the highest to the fifth in the sampling part of the surface of the object, and the fifth from the lowest. It is a parameter that indicates the sum of the absolute value from the average line of the valley bottom up to (JIS B0601). In the present invention, Rz (μm) was obtained from the extracted portion 149 μm.
[0033]
The multilayer wiring board of the present invention can be manufactured by the following method for manufacturing a multilayer wiring board of the present invention.
With reference to FIG. 1, the process of manufacturing a multilayer wiring board using the insulating resin composition of the present invention will be described. (A)-(i) of FIG. 1 is sectional drawing explaining an example of the process of manufacturing a multilayer wiring board.
First, a circuit board 3 in which a first circuit layer 1a is formed on an insulating substrate 2 is prepared [see FIG. 1 (a)].
The circuit board is, for example, an inner layer substrate having a first circuit layer (inner layer wiring) formed on the surface, and a known laminated plate used in a normal wiring board as the inner layer substrate, for example, glass cloth-epoxy Resin, paper-phenol resin, paper-epoxy resin, glass cloth / glass paper-epoxy resin, and the like can be used and are not particularly limited. Further, a BT substrate impregnated with a bismaleimide-triazine resin, a polyimide film substrate using a polyimide film as a base material, and the like can also be used.
[0034]
Further, there is no particular limitation on the method for forming the circuit layer 1a, and a subtractive method in which an unnecessary portion of the copper foil is removed by etching using a copper-clad laminate obtained by bonding a copper foil and the insulating substrate, A known method for manufacturing a wiring board, such as an additive method for forming a circuit by electroless plating at a required portion of an insulating substrate, can be used.
Although FIG. 1A shows an example in which the circuit layer 1a is formed on one side of the insulating substrate 2, the circuit layer 1a can also be formed on both sides of the insulating substrate 2 using a double-sided copper-clad laminate.
[0035]
Next, if necessary, the surface of the circuit layer 1a is surface-treated in a state suitable for adhesiveness. This method is also not particularly limited. For example, a copper oxide needle crystal is formed on the surface of the circuit layer 1a with an aqueous alkali solution of sodium hypochlorite, and the formed copper oxide needle crystal is converted into an aqueous dimethylamine borane solution. A known production method such as immersion and reduction can be used.
[0036]
(A) Then, an insulating resin composition layer 4b which is a layer of the insulating resin composition of the present invention is formed on one or both sides of the circuit board 3 having the circuit layer 1a [see FIG. 1 (b)]. In FIG. 1B, the circuit layer 1 a is formed on one side of the circuit board 3, but may be formed on both sides, and in this case, the insulating resin composition layer 4 b can be formed on both sides of the circuit board 3. . Moreover, there is no restriction | limiting in particular in this formation method. For example, a method of producing an insulating resin composition varnish as described above, applying the varnish on a support, drying to produce an insulating film with a support, and laminating it on the circuit board 3 Is mentioned. Moreover, the method of coating on the single side | surface or both surfaces of the circuit board 3 which has the direct circuit layer 1a using a curtain coat or a roll coater, and forming a layer is mentioned.
[0037]
When the varnish is applied on the circuit board, a general application method such as bar coating, spin coating, or screen printing can be used. Moreover, when apply | coating a varnish on a support body, a comma coater, a bar coater, a kiss coater, a roll coater etc. can be utilized, and it is used suitably by the thickness of an insulating film. In any case, the coating thickness and the drying conditions after coating are not particularly limited, but it is preferable that the solvent used for the varnish is volatilized by 80% by weight or more.
Examples of the support to which the varnish is applied include a plastic film such as PET and a metal foil. When the support is peeled and removed after the varnish is cured, a releasable plastic film or the like is preferable. Further, when the support is a metal foil such as a copper foil, it can be continuously used for the second circuit layer described later without peeling. The insulating resin composition layer of the insulating film with the support is directed to the circuit board 3 by using a laminating method or a pressing device so that the insulating resin composition layer faces the surface of the circuit board in contact with the circuit layer.
[0038]
(B) After that, the insulating resin composition layer is heated and cured to form the first insulating layer 6c, which is an insulating resin layer [see FIG. 1 (c)], but the curing temperature is the later plating treatment or copper annealing. It is performed at a temperature and time considering the processing. In other words, if the curing is advanced too much, the adhesiveness with copper is lowered during the subsequent plating process, or if the curing is not sufficient, a phenomenon may occur in which it is eroded by the alkaline treatment solution during the plating treatment and dissolved in the plating solution. . Considering these matters, it is desirable to cure by applying a heat treatment at 150 to 190 ° C. for 30 to 90 minutes.
When the insulating film with a support is used, the pressure lamination step and the heat curing step may be performed simultaneously or separately. The pressurization lamination conditions may be as long as the unevenness of the circuit layer 1a is embedded in the semi-cured insulating resin composition, and usually 0.5 to 20 MPa is preferable.
[0039]
Furthermore, a via hole 5c can be formed in the first insulating layer 6c in order to connect the first circuit layer 1a, which is an inner layer circuit, and the outer layer circuit [see FIG. 1 (c)]. There is no restriction | limiting in particular as a formation method of this via hole, A laser method, a sandblasting method, etc. can be used.
[0040]
(C) Next, the following circuit processing is performed to form the second circuit layer 1d, and further, the interlayer connection between the first circuit layer 1a and the second circuit layer 1d is formed [FIG. (See (d)).
First, when forming the 2nd circuit layer 1d which is an outer layer circuit by a plating method, it is preferable to roughen the 1st insulating layer 6c. As the roughening liquid, an oxidizing roughening liquid such as a chromium / sulfuric acid roughening liquid, an alkaline permanganic acid roughening liquid, a sodium fluoride / chromium / sulfuric acid roughening liquid, or a borofluoric acid roughening liquid can be used. As the roughening treatment, for example, first, as a swelling liquid, an aqueous solution of diethylene glycol monobutyl ether and NaOH is heated to 70 ° C., and the first insulating layer 6 c is immersed for 5 minutes. Next, as a roughening solution, an aqueous solution of KMnO and NaOH is heated to 80 ° C. and immersed for 10 minutes. Subsequently, a neutralizing solution such as stannous chloride (SnCl ₂ ) For 5 minutes at room temperature to neutralize.
[0041]
After the roughening treatment, a plating catalyst applying treatment for attaching palladium is performed. The plating catalyst treatment is performed by immersing in a palladium chloride plating catalyst solution.
Next, the electroless plating layer (conductor layer) having a thickness of 0.3 to 1.5 μm is formed on the entire surface of the first insulating layer 6c (including the inner surface of the via hole when a via hole is formed) by dipping in an electroless plating solution. ). If necessary, further electroplating is performed to obtain a necessary thickness. The electroless plating solution used for electroless plating can be a known electroless plating solution, and is not particularly limited. Also, electroplating can be performed by a known method and is not particularly limited. These platings are preferably copper platings.
Further, unnecessary portions can be removed by etching to form the second circuit layer 1d and the interlayer connection between the first circuit layer 1a and the second circuit layer 1d.
[0042]
When an insulating film with a copper foil is used for forming the insulating resin composition layer, the outer layer circuit (second circuit layer 1d) is formed using an etching method. There is no restriction | limiting in particular in the method using this etching method, A pattern plating method can also be used using the ultra-thin copper foil about 3 micrometers thick. Interlayer connection when this insulating film with copper foil is used can be formed by plating or the like after providing a via hole by a laser method or the like.
As a method for forming the second circuit layer 1d, a catalyst for electroless plating is applied to the surface of the roughened insulating layer to deposit electroless plated copper on the entire surface. In addition to the method of forming the circuit conductor by electroplating to the required thickness and removing unnecessary portions by etching, an insulating layer containing a plating catalyst is used to form a plating resist and only the necessary portions A method of forming a circuit by electroless plating, a method of roughening an insulating layer not containing a plating catalyst, forming a plating resist after applying a plating catalyst, and forming a circuit by electroless plating only at necessary places, etc. it can.
[0043]
Further, the surface treatment of the second circuit layer 1d is performed in the same manner as the surface treatment of the first circuit layer 1a, and the insulating resin composition layer 4e is formed in the same manner as the formation of the insulating resin composition layer 4b [ See FIG. 1 (e)]. Next, the insulating resin composition layer 4e is cured to form the second insulating layer 6f, and a via hole 5f is formed [see FIG. 1 (f)]. Further, a third circuit layer 1g is formed in the same manner [see FIG. 1 (g)].
Thereafter, a multilayer wiring board having a large number of layers can be produced by repeating the same process.
[0044]
【Example】
EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to these Examples.
Example 1
(1) Glass cloth base epoxy resin double-sided copper-clad laminate [MCL-E-67 manufactured by Hitachi Chemical Co., Ltd. having a copper foil thickness of 18 μm, a substrate thickness of 0.8 mmt, and a double-sided roughened foil on both sides (trade name) )] Was etched on one side to produce a circuit board having a circuit layer (hereinafter referred to as a first circuit layer) on one side.
[0045]
(2) An insulating resin composition having the following composition is blended in a container, and the entire resin blend solution is dispersed for about 30 minutes using a bead mill, and then filtered through a 380 mesh nylon mesh to obtain a varnish of the insulating resin composition. Produced. The equivalent of the thermosetting agent to the epoxy at this time was 1.0 equivalent. The insulating resin composition varnish was coated on a PET film and dried at 100 ° C. for 10 minutes to prepare a roll of an insulating film with a support having a thickness of 30 ± 3 μm. Further, the batch-type vacuum pressurization laminator MVLP-500 (trade name, manufactured by Meiki Co., Ltd.) with the insulating film with support and the circuit board facing the surface of the circuit board in contact with the insulating resin composition layer. Were laminated.
[0046]
[composition]
(A) Epoxy resin having biphenyl structure and novolak structure: NC3000S-H
(Nippon Kayaku Co., Ltd., trade name) 82 parts by weight
(B) Carboxylic acid-modified acrylonitrile butadiene rubber (linear NBR) PNR-1H (product name, manufactured by JSR Corporation) and particulate NBR XER-91 (JSR Corporation, product name) in a solid content ratio of 1 12 parts by weight of mixture mixed in 1
(C) Phosphorus-containing phenol resin: HCA-HQ (trade name, manufactured by Sanko Co., Ltd.)
(E) Methyl ethyl ketone having a solid content concentration of 30% by weight as the solid content concentration of the above phosphorus-containing phenol resin in methyl ethyl ketone is prepared, and (F) surface activity of polycarboxylic acid type that becomes 1.5% by weight of the amount of phosphorus-containing phenol resin. An agent L-1820 (trade name, manufactured by Kao Corporation) was prepared. The prepared methyl ethyl ketone and polycarboxylic acid type surfactant were stirred with a three-one stirrer at a rotation speed of 700 rpm, and a phosphorus-containing phenol resin was added little by little while stirring for about 1 hour to obtain a dispersion. This phosphorus-containing phenol resin dispersion was used. In Table 1, “premix” is indicated.

[0047]
(3) Next, after peeling off the PET film, the insulating resin composition layer was cured under a curing condition of 180 ° C.-60 minutes to obtain a first insulating layer.
(4) A via hole for interlayer connection is formed in this first insulating layer by Hitachi Via Mechanics CO. ₂ A laser processing machine (LCO-1B21 type) was used and processed under conditions of a beam diameter of 80 μm, a frequency of 500 Hz, a pulse width of 5 μsec, and a shot number of 7.
[0048]
(5) In order to chemically roughen the first insulating layer, an aqueous solution of diethylene glycol monobutyl ether: 200 ml / L, NaOH: 5 g / L was prepared as a swelling liquid, heated to 70 ° C. and immersed for 5 minutes. did. Next, as a roughening solution, KMnO ₄ : An aqueous solution of 60 g / L and NaOH: 40 g / L was prepared, heated to 80 ° C. and immersed for 10 minutes. Subsequently, the neutralization solution (SnCl ₂ : 30 g / L, HCl: 300 ml / L) and neutralized by immersion for 5 minutes at room temperature.
[0049]
(6) In order to form the second circuit layer on the surface of the first insulating layer, first, PdCl ₂ A plating solution CUST-201 (Hitachi) for electroless copper plating is immersed in HS-202B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a catalyst for electroless plating, containing aluminum. (Trade name) manufactured by Kasei Kogyo Co., Ltd.) was immersed at room temperature for 15 minutes and further subjected to copper sulfate electrolytic plating. Thereafter, annealing was performed at 180 ° C. for 30 minutes to form a conductor layer having a thickness of 20 μm on the surface of the first insulating layer and the via hole.
Next, in order to remove unnecessary portions of the plating conductor by etching, first, the oxide film on the copper surface is removed by polishing with # 600, followed by forming an etching resist, then etching, and then removing the etching resist. Then, a second circuit including a via hole connected to the first circuit layer was formed.
[0050]
(7) Further, in order to make a multilayer, the surface of the second circuit conductor is placed in an aqueous solution of sodium chlorite: 50 g / l, NaOH: 20 g / l, trisodium phosphate: 10 g / l at 85 ° C. for 20 minutes. It was immersed, washed with water, and dried at 80 ° C. for 20 minutes to form copper oxide irregularities on the surface of the second circuit conductor.
(8) The steps (2) to (7) were repeated to produce a three-layer multilayer wiring board.
[0051]
(Example 2)
In Example 1, the inorganic filler was spherical silica (Admafine SO-25R) alone without using aluminum hydroxide, and the blending amount was 32 parts by weight. Others were performed in the same manner as in Example 1.
[0052]
(Example 3)
In Example 1, instead of producing an insulating film with a support and laminating the film on the first circuit layer, the varnish of the insulating resin composition was directly applied to the surface side of the circuit board having the first circuit layer. It apply | coated with the roll coater and it dried at 110 degreeC for 10 minute (s), and formed the insulating resin composition layer with a film thickness of 30 +/- 4micrometer. Others were performed in the same manner as in Example 1.
[0053]
(Example 4)
In Example 1, instead of methyl ethyl ketone, a one-to-one mixed solvent of methyl ethyl ketone and cyclohexanone was used, and the surfactant was further changed to imidazoline type surfactant homogenol L-95 (trade name, manufactured by Kao Corporation). . Others were performed in the same manner as in Example 1.
[0054]
(Example 5)
In Example 1, it carried out like Example 1 except not using surfactant.
(Example 6)
In Example 1, a phosphorus-containing phenol resin dispersion was not prepared, and the same procedure as in Example 1 was carried out except that the phosphorus-containing phenol resin, methyl ethyl ketone and surfactant were blended in the container simultaneously with other components.
(Example 7)
In Example 6, it carried out like Example 6 except not using surfactant.
[0055]
(Comparative Example 1)
In Example 1, dimethylformamide (solubility parameter 12.1) was used instead of methyl ethyl ketone. Others were performed in the same manner as in Example 1.
[0056]
(Comparative Example 2)
In Example 1, the phosphorus-containing phenol resin was used in a powder state without using methyl ethyl ketone. Others were performed in the same manner as in Example 1.
(Comparative Example 3)
In Example 1, a phosphorus-containing phenol resin was used in a powder state without using methyl ethyl ketone and a surfactant. Others were performed in the same manner as in Example 1.
(Comparative Example 4)
In Example 1, it changed into diethyl ether (solubility parameter 7.4) instead of methyl ethyl ketone. The others were carried out in the same manner as in Example 1. As a result, the varnish could not be applied because it was separated and could not be evaluated.
[0057]
For the resin composition varnish and multilayer wiring board produced as described above, (1) flame retardancy, (2) tensile elongation of the insulating resin coating film, and (3) surface roughness after the insulating resin is roughened (4) Adhesive strength with outer layer circuit, (5) Crack generation rate under insulation heat cycle test, (6) Insulation reliability acceleration test under unsaturated atmosphere, (7) 288 ° C solder heat resistance The test was conducted. The results are shown in Table 1.
[0058]
[Flame retardance]
Used as an inner layer circuit board in each example and comparative example, the glass cloth base epoxy resin double-sided copper-clad laminate was etched to produce a substrate completely stripped of copper foil, on both sides of this substrate, The said varnish was apply | coated so that it might become the insulating resin thickness of 150 micrometers of one side, and the insulating resin composition layer was formed. And the flame-retardant test piece was produced by heating after 180 degreeC-1 hour.
The test method was tested according to the UL-94 method.
[0059]
[Tensile elongation of coating film]
The varnish in each Example and Comparative Example was applied to a copper foil, and cured by applying the same heat treatment at 180 ° C. for 60 minutes as in the production of the wiring board. And the insulating resin coating film which etched and removed copper was obtained. This insulating resin coating film was cut into a thickness of 30 μm, a width of 10 mm, and a length of 100 mm, and the insulating resin coating film was pulled and broken by an autograph pull test (chuck distance 50 mm) at a pulling speed of about 5 mm / min. Tensile elongation was determined.
[0060]
[Surface roughness after roughening: Rz]
A test piece was prepared by removing copper from the outer layer circuit of the multilayer wiring board obtained in each Example and Comparative Example by etching. This test piece was cut into about 2 mm square. Using the ultra-deep shape measurement microscope product name VK-8500 manufactured by Keyence Corporation, select a measurement length of 149 μm from the surface of the test piece, and observe under the conditions of a magnification of 2000 times and a resolution of 0.05 μm. Ten-point average roughness in 149 μm (Rz) was calculated.
[0061]
[Adhesion strength with outer layer circuit]
A part having a width of 10 mm and a length of 100 mm is formed on a part of the L1 circuit layer (third circuit layer) of the multilayer wiring board obtained in each example and comparative example, and one end thereof is peeled off at the circuit layer / resin interface. The load when gripping with a gripper and peeling off at room temperature at a pulling speed of about 50 mm / min in the vertical direction was measured.
[0062]
[Crack occurrence rate of insulation resin under thermal cycle test]
The copper foil of Hitachi Chemical Co., Ltd. MCL-E-67 (substrate thickness 0.8 mm, product name) used for the inner circuit board was completely dissolved and removed by etching. The varnish obtained in each of Examples and Comparative Examples was formed on one side with a thickness of 30 ± 5 μm. This substrate with insulating resin was processed in the same manner as in the example, and an outer layer circuit was formed on the insulating resin. Then, in order to form a pattern in which the outer layer circuit remains 2 mm square, an etching resist (H-K425, manufactured by Hitachi Chemical Co., Ltd., trade name) is applied on the copper surface at 100 ° C., 0.5 m / min, pressure 0.5 MPa · Laminated under the conditions of s. After that, exposure 80mJ / cm ² Then, exposure was carried out through a photomask prepared so that the outer layer circuit remained 2 mm square. Next, development was performed using a developer of a 1.0% aqueous solution of sodium carbonate at 30 ° C., a pressure of 0.1 MPa · s, and a development time of 60 seconds. Further, the resist was stripped with an aqueous solution of sodium hydroxide and dried. Then, copper was etched with a ferric chloride aqueous solution to produce a crack resistance evaluation pattern in which the outer layer circuit was 2 mm square.
This sample was subjected to a thermal cycle test at −55 ° C. to 125 ° C. (15 minutes each), observed with a microscope for cracks in the insulating resin likely to occur at the 2 mm square corners of the outer layer circuit, and until cracks occurred. Expressed as the number of cycle tests.
[0063]
[Insulation reliability acceleration test under unsaturated atmosphere]
In the multilayer wiring boards produced in each of the examples and comparative examples, lead wires were fixed to the terminal portions by soldering so that a voltage could be applied in the interlayer direction of the insulating resin. The insulation resistance in the interlayer direction of the insulating resin was measured by applying 50 V for 1 minute at room temperature. Furthermore, using this as a sample, the sample was taken out at a predetermined time while applying a DC voltage of 10 V in an unsaturated atmosphere of 130 ° C. and 85% RH, and measured at 50 V for 1 minute at room temperature. ⁸ The time showing Ω or more was expressed as the insulation reliability time.
[0064]
[288 ° C solder heat resistance]
The multilayer wiring boards produced in each Example and Comparative Example were cut into 25 mm squares, floated in a solder bath adjusted to 288 ° C. ± 2 ° C., and the time until blistering was examined.
[0065]
[Table 1]

[0066]
From Table 1, the characteristics of the multilayer wiring board using the insulating resin composition of the present invention are excellent in flame retardancy and have a very thin film thickness of about 30 μm as shown in Examples 1-7. However, it has high insulation reliability and also exhibits good results in crack resistance due to the high elongation rate of the coating film. In addition, although the surface roughness after roughening is small, the adhesive strength with the outer layer copper is good, suitable for fine wiring, insulation reliability, 288 ° C solder heat resistance, and environment-friendly multilayer wiring It is possible to produce a plate.
On the other hand, the multilayer wiring boards shown in Comparative Examples 1 to 3 that do not essentially contain the insulating resin composition of the present invention were confirmed to have a tendency that the insulation reliability was extremely deteriorated and the solder heat resistance was lowered.
[0067]
【The invention's effect】
According to the present invention, the insulating resin composition has flame retardancy without using any bromine compound that may adversely affect the environment, and has high insulation reliability even in a very thin film thickness of 30 μm. Can provide. In addition, it achieves high solder heat resistance that can be used for lead-free and high tensile elongation of insulating resin coating that can withstand mechanical and thermal stress concentration, and also maintains adhesive strength and maintains the adhesive strength. It is possible to provide a multilayer wiring board having excellent characteristics that can cope with fine wiring by setting the surface roughness Rz within a range of 1 to 3 μm.
[Brief description of the drawings]
FIGS. 1A to 1I are cross-sectional views illustrating an example of a process for manufacturing a multilayer wiring board.
[Explanation of symbols]
1a First circuit layer
1d Second circuit layer
1g Third circuit layer
2 Insulating substrate
3 Circuit board
4b, 4e Insulating material composition layer
5c, 5f via hole
6c First insulating layer
6f Second insulating layer

Claims

(A) an epoxy resin having a biphenyl structure and a novolak structure, (B) an acrylonitrile butadiene copolymer, (C) a phosphorus-containing phenol compound , (D) a thermosetting agent, and (E) a solubility parameter of 7 And (C) a phosphorus-containing phenol compound, which is a compound having a structure of the following formula (I) :
Advance (E) solubility parameter obtaining a dispersion of the phosphorus-containing phenol compound are dispersed in a liquid (C) a phosphorus-containing phenol compound, comprising at least part of the solvent in the range of 7.5 to 10.5 step The manufacturing method of the insulating resin composition characterized by including.

The method for producing an insulating resin composition according to claim 1, wherein in the step of obtaining a dispersion, (F) a surfactant is added to a liquid containing at least a part of the solvent.

The method for producing an insulating resin composition according to claim 1 or 2, wherein the concentration of the phosphorus-containing phenol compound in the dispersion is in the range of 10 to 60% by weight in terms of solid content.

The insulating resin composition manufactured by the manufacturing method in any one of Claims 1-3.

(A) an epoxy resin having a biphenyl structure and a novolak structure, (B) an acrylonitrile butadiene copolymer, (C) a phosphorus-containing phenol compound , (D) a thermosetting agent, and (E) a solubility parameter of 7 and a solvent in the range of .5~10.5, (C) a phosphorus-containing phenol compound, an insulating resin composition which is a compound of the structure of the formula (I).

The insulating resin composition according to claim 5, further comprising (F) a surfactant.

(E) A dispersion obtained by dispersing (P) a phosphorus-containing phenol compound in advance in a liquid containing at least a part of a solvent having a solubility parameter in the range of 7.5 to 10.5. 6. The insulating resin composition according to 6.

The insulating resin composition according to claim 7, wherein the dispersion contains (F) a surfactant.

The insulating resin composition according to claim 7 or 8, wherein the concentration of the phosphorus-containing phenol compound in the dispersion is in the range of 10 to 60% by weight in terms of solid content.

The epoxy resin having the (A) biphenyl structure and the novolak structure is 35 to 60% by weight in the total solid content of the insulating resin composition, and the (A) epoxy resin and the (B) acrylonitrile butadiene copolymer The insulating resin composition according to any one of claims 4 to 9, wherein a blend ratio of the solid content with the polymer is 80/20 to 95/5 by weight.

Furthermore, (G) an inorganic filler is included, and the phosphorus content in the (C) phosphorus-containing phenol compound is 0.7 to 3.0% by weight in the solid content of the insulating resin composition excluding the (G) inorganic filler. Item 11. The insulating resin composition according to any one of Items 4 to 10.

A multilayer wiring board in which an insulating layer and an outer layer circuit layer are sequentially laminated on one side or both sides of a substrate having an inner layer circuit,
A multilayer wiring board, wherein the insulating layer includes an insulating resin layer formed by curing the insulating resin composition according to any one of claims 4 to 11.

The multilayer wiring board according to claim 12, wherein the insulating resin layer has a thickness of 30 μm or less.

The multilayer wiring board according to claim 12 or 13, wherein the tensile elongation of the insulating resin layer is 4% or more.

The multilayer wiring board according to claim 12, wherein the surface roughness of the interface between the insulating resin layer and the outer circuit layer is 1 to 3 in terms of Rz.

A step (a) of laminating an insulating layer containing the layer of the insulating resin composition according to any one of claims 4 to 11 on a substrate having an inner layer circuit;
A step (b) of obtaining an insulating resin layer by curing the insulating resin composition;
Forming an outer circuit layer on the surface of the insulating layer (c),
The manufacturing method of the multilayer wiring board containing this.

The method for manufacturing a multilayer wiring board according to claim 16, wherein the step (b) includes a step of roughening the surface of the insulating resin layer with an oxidizing roughening liquid after obtaining the insulating resin layer.

The method for manufacturing a multilayer wiring board according to claim 16 or 17, wherein in the step (c), an outer layer circuit is formed by copper plating.

The said process (I) apply | coats and dries the varnish of an insulating resin composition to a support body, produces a film with a support body, and laminate | stacks this insulating film with a support body on the board | substrate which has an inner layer circuit. The method for producing a multilayer wiring board according to any one of 18.