JP3781381B2 - Laminated body and wiring board using the same - Google Patents

Description

（但し、式中Ｒ₂ 及びＲ₄ は２価の有機基を示し、Ｒ₁ 及びＲ₃ は１価の有機基を示し、ｐ及びｑは１より大きい整数を示す）で表されるジアミノシロキサン、2,2-ビス[4-(p-アミノフェノキシ）フェニル] ヘキサフルオロプロパン、2,2-ビス[4-(3-アミノフェノキシ）フェニル] ヘキサフルオロプロパン、2,2-ビス[4-(2-アミノフェノキシ）フェニル] ヘキサフルオロプロパン、2,2-ビス[4-(4-アミノフェノキシ)-3,5-ジメチルフェニル] ヘキサフルオロプロパン、2,2-ビス[4-(4-アミノフェノキシ)-3,5-ジトリフルオロメチルフェニル] ヘキサフルオロプロパン、p-ビス(4- アミノ−2-トリフルオロメチルフェノキシ）ベンゼン、 4,4'-ビス（4-アミノ−2-トリフルオロメチルフェノキシ）ビフェニル、 4,4'-ビス（4-アミノ−3-トリフルオロメチルフェノキシ）ビフェニル、 4,4'-ビス（4-アミノ−2-トリフルオロメチルフェノキシ）ジフェニルスルホン、 4,4'-ビス（4-アミノ−5-トリフルオロメチルフェノキシ）ジフェニルスルホン、2,2-ビス[4-(4-アミノ−3-トリフルオロメチルフェノキシ）フェニル] ヘキサフルオロプロパン、ベンジジン、3,3',5,5'-テトラメチルベンジジン、オクタフルオロベンジジン、 3,3'-メトキシベンジジン、o-トリジン、m-トリジン、 2,2',5,5',6,6'-ヘキサフルオロトリジン、 4,4"-ジアミノターフェニル、4,4"'-ジアミノクォーターフェニル等のジアミン類、並びにこれらのジアミンとホスゲン等の反応によって得られるジイソシアネート類がある。
【００１２】
また、テトラカルボン酸無水物並びにその誘導体としては次の様なものが挙げられる。なお、ここではテトラカルボン酸として例示するが、これらのエステル化物、酸無水物、酸塩化物も勿論使用できる。ピロメリット酸、3,3',4,4'-ビフェニルテトラカルボン酸、3,3',4,4'-ベンゾフェノンテトラカルボン酸、3,3',4,4'-ジフェニルスルホンテトラカルボン酸、3,3',4,4'-ジフェニルエーテルテトラカルボン酸、2,3,3',4'-ベンゾフェノンテトラカルボン酸、2,3,6,7-ナフタレンテトラカルボン酸、1,2,5,6-ナフタレンテトラカルボン酸、3,3',4,4'-ジフェニルメタンテトラカルボン酸、2,2-ビス(3,4−ジカルボキシフェニル) プロパン、2,2-ビス（3,4-ジカルボキシフェニル) ヘキサフルオロプロパン、 3,4,9,10-テトラカルボキシペリレン、2,2-ビス[4-(3,4-ジカルボキシフェノキシ) フェニル] プロパン、2,2-ビス[4-(3,4-ジカルボキシフェノキシ) フェニル] ヘキサフルオロプロパン、ブタンテトラカルボン酸、シクロペンタンテトラカルボン酸等がある。また、トリメリット酸及びその誘導体も挙げられる。
【００１３】
また、反応性官能基を有する化合物で変成し、架橋構造やラダー構造を導入することもできる。例えば、次のような方法がある。
（ａ）下記一般式（３）で表される化合物で変成することによって、ピロロン環やイソインドロキナゾリンジオン環等を導入する。
【化４】

〔但し、式中Ｒ₅ は２＋Ｘ価（Ｘは１又は２である）の芳香族残基を示し、Ｚは−ＮＨ₂ 基、−ＣＯＮＨ₂ 基又は−ＳＯ₂ ＮＨ₂ 基から選択された置換基であってアミノ基に対してオルソ位である。〕
（ｂ）重合性不飽和結合を有するアミン、ジアミン、ジカルボン酸、トリカルボン酸、テトラカルボン酸の誘導体で変成して硬化時に橋かけ構造を形成する。不飽和化合物としては、マレイン酸、ナジック酸、テトラヒドロフタル酸、エチニルアニリン等が使用できる。
（ｃ）フェノール性水酸基あるいはカルボン酸を有する芳香族アミンで変成し、この水酸基又はカルボキシル基と反応しうる橋かけ剤を形成する。
【００１４】
本発明はこの様にして得られたポリイミド前駆体を感光性樹脂層と接してフィルム状に設けるわけであるが、その樹脂層全体の硬化後の熱膨張係数は３×１０^-5／℃以下であることが好ましい。特にフレキシブルプリント基板等の柔軟な回路上に設ける場合、熱膨張係数が３×１０^-5／℃を越えるとイミド化反応等の高温熱処理後冷却時に回路が反ってしまい、実用上支障が生じやすい。
【００１５】
本発明においてはポリイミド前駆体樹脂層が低熱膨張性樹脂層と良接着性樹脂層の少なくとも２層の構造を有することが必要である。
【００１６】
低熱膨張性樹脂層は硬化後に３×１０^-5／℃未満の熱膨張係数を有することが好ましく、それ以上であると得られる基板の反りが生じて好ましくない。低熱膨張性樹脂層として好ましくは下記一般式（１）あるいは一般式（２）で示される繰り返し単位を有するポリイミド前駆体が好ましく、熱膨張係数が小さく、かつ屈曲性等の機械的特性に優れている。
【化５】

【００１７】
これらの繰り返し単位の他に熱膨張係数のコントロール、あるいは機械的特性の調整等を目的として、前期化合物等を用いて共重合あるいはブレンドすることも可能である。また種々の特性改良を目的として無機質、有機質、又は金属等の粉末、繊維、チョプドストランド等を混合して使用することもできる。また硬化時の回路の酸化を防ぐ目的で酸化防止剤等の添加剤あるいは接着性の向上を目的としてシランカップリング剤を加えることも可能である。また可とう性の向上あるいは流れ性、接着性の向上等を目的として異種のポリマーをブレンドすることも可能である。
【００１８】
良接着性樹脂層は基板との接着性を高めるために必須であり、また必要に応じ、低熱膨張性樹脂層を間に挟んだ３層構造にして、回路に張り合わせた後、更に後加工で他の部材、例えば補強板等との接着の際の接着性を発現させることも可能である。
【００１９】
本発明でいう良接着性樹脂は上述の炭素数１６個以上の芳香族テトラカルボン酸又はその誘導体と炭素数１２個以上の芳香族ジアミン化合物とを主に反応させて得ることができる。
【００２０】
これらの主構造以外に接着性、耐熱性、充填性等の諸特性の改善を目標に種々のジアミン及びテトラカルボン酸化合物を共重合することが可能であり、また別途合成したポリイミド前駆体樹脂をブレンドすることも差し支えない。更に、同様の目的で異種の熱可塑性ポリマー、ゴム等を良接着性樹脂層にブレンドしてより高い接着力を発現させることも可能である。特に銅箔光沢面との十分な接着力が要求される場合、ニトリルブタジエンゴム等をブレンドすることは有用である。また、回路の酸化や樹脂の劣化を防止する目的で酸化防止剤等の添加剤を加えたり、流れ性、表面性を制御する目的で無機粒子を添加することも可能である。
【００２１】
この良接着性樹脂層と低熱膨張性樹脂層との厚みの比率は任意に設定可能であるが、一般に、前述の芳香族テトラカルボン酸と芳香族ジアミンから得られる良接着性樹脂層は熱膨張係数が５×１０^-5／℃以上であるためにその層が厚すぎると得られる基板の反りが生じて好ましくない。
【００２２】
また、この多層のポリイミド前駆体樹脂層は有機溶剤を１０部以上含むことが好ましく、それ未満であると回路への充填性が不十分となり、凹凸部に気泡が生じ易い。有機溶剤としては、前述の非プロトン系極性溶媒が好ましく、ジメチルフォルムアミド、ジメチルアセトアミド、Ｎメチルピロリドン、ジメチルスルフォキサイド等が挙げられる。
【００２３】
ポリイミド前駆体樹脂層の厚みは２μｍから３００μｍが好ましく、それ未満であると、回路の絶縁に対する信頼性に乏しく、また折り曲げ等の機械的特性が低い。３００μｍを越えるとイミド化反応の際劣化反応が生じやすく好ましくない。
【００２４】
この様にして得られたポリイミド前駆体を感光性樹脂層に接触して層を形成するわけであるが、その形成方法は任意の方法が可能である。より作業性に優れた方法としては離形フィルム上に感光性樹脂を塗工した後、ポリイミド前駆体樹脂溶液を塗工する。又は逆に離型フィルム上にポリイミド前駆体樹脂溶液を塗布した後に、感光性樹脂溶液を塗布することも可能である。
【００２５】
ポリイミド前駆体樹脂層を多層に形成する方法についても同様に任意の方法が可能であるが、好ましくはその厚み精度の点で逐次塗工であり、その塗工形式としてはリバース塗工、ナイフ塗工、ダイ塗工等が挙げられる。
【００２６】
必要に応じ更に保護フィルムを張り合わせて塵埃等から樹脂層を保護することも可能である。
【００２７】
離形フィルムとしてはポリエステルフィルム、ポリロピレンフィルム、ポリイミドフィルム、ポリエチレンフィルム、ポリ塩化ビニルフィルム等の一般のフィルムが選択可能であり、より離形性を増すためにシリコーン化合物等の離形剤が表面にコートさせたフィルムがより好ましい。
【００２８】
保護フィルムとしては上記フィルム単体もしくは必要に応じ粘着剤を塗布したフィルムが用いられる。
【００２９】
塗工後のポリイミド前駆体樹脂溶液の乾燥は感光性樹脂あるいは離形フィルムの劣化を起こさない範囲で選択可能であるが、好ましくは１８０℃以下である。その温度を越えるとイミド化反応が起こり、その後の回路へのラミネートの際樹脂の流れ性が落ちることにより充填性が低下したり、あるいはパターニングの際エッチング時間が長くなり、好ましくない。
【００３０】
この様にして得られた積層体は任意の回路パターンが描かれた回路基板上にポリイミド前駆体樹脂層が接する様に積層される。回路基板としてはガラスエポキシ等の硬質基板、あるいはポリイミドフィルムを用いたフレキシブルプリント基板等の任意の回路基板が可能であるが、ポリイミド前駆体樹脂層は、保護膜とするために高温で硬化する必要があるため、ガラス／マレイミド硬質基板あるいは無接着剤フレキシブルプリント基板等の耐熱性に優れた回路基板がより好ましい。
【００３１】
積層方法としては熱プレス機あるいはロールツウロールのラミネーターにより可能である。この際樹脂の充填性を増すために２００℃以下の加熱をすればより好ましい。また基板との密着性をより向上させるため界面に前述の非プロトン性極性溶媒等の有機溶剤等の浸し液を用いても差支えない。
【００３２】
次に絶縁層であるポリイミド前駆体樹脂層を任意の形状に加工するために、任意のネガパターンあるいはポジパターンを離形フィルム上あるいは感光性樹脂層に直接重ね、露光を行なう。更に感光性樹脂の現像を行なった後、アルカリ性の溶液によりポリイミド前駆体のエッチングを行なう。エッチングに際しその速度を上げるために加熱することも可能である。その際温水によるエッチングをアルカリエッチングの後に併用すればより効果的にエッチングが行われる。最後に、残っている感光性樹脂層を剥離してパターン化されたポリイミド前駆体絶縁樹脂層が得られる。
【００３３】
この様にして得られた回路はイミド化反応である硬化反応を行なうため高温の熱処理が施される。最高の熱処理温度としては２００℃以上、より好ましくは２５０℃以上である。硬化温度が２００℃未満であれば耐熱性、耐薬品性が劣り好ましくない。加熱は熱風オーブン等を用いたバッチ熱処理あるいはロールツウロールの加熱いずれでも可能である。また不活性雰囲気で行なえば回路の酸化が抑えられより好ましい。
【００３４】
本発明の積層体を用いて任意の回路の絶縁保護を行うことが可能であるが、特に無接着剤銅張積層板と組み合わせることにより、絶縁体がすべてポリイミドである理想的なフレキシブルプリント配線板が作製可能である。
【００３５】
また本発明の積層体の加工とメッキ加工を逐次行って多層配線板を作製することも可能である。このようにして得られる多層配線板はドリル穴明け加工等が不用で回路の平坦化薄層化が図れ、誘電率が低いといった特長を有し、理想的な多層配線板が得られる。
【００３６】
【実施例】
以下、実施例に基づいて、本発明を具体的に説明するが、本発明はこれに限定されないことは勿論である。
【００３７】
熱膨張係数はイミド化反応が十分終了した試料を用い、サーモメカニカルアナライザー（ＴＭＡ）を用いて行い、２５０℃に昇温後１０℃／ｍｉｎで冷却して２４０℃から１００℃までの平均の熱膨張係数を算出して求めた。
【００３８】
耐ハンダ性は、７６％ＲＨで２４時間放置した回路をハンダ浴に１分間浸漬し、膨れ、剥がれの生じない最高の温度を１０℃刻みで調べた。
【００３９】
加工精度は直径が１０μｍ刻みで異なる円形のパターンを用いポリイミド前駆体樹脂層をエッチング加工して目視により良好な形状を有する直径の大きさにより判定した。
【００４０】
合成例１
温度計、塩化カルシウム管、攪拌棒及び窒素吸込口を取り付けた３００ｍｌの４つ口フラスコに毎分２００ｍｌの窒素を流しながら、 2'-メトキシ-4,4'-ジアミノベンズアニリド（ＭＡＢＡ）０．０７モル及び 4,4'-ジアミノジフェニルエーテル（ＤＡＰＥ）０．０３モルを２２０ｍｌのジメチルアセトアミド（ＤＭＡｃ）中に攪拌溶解させた。この溶液を水冷浴中で１０℃以下に冷却しながら、無水ピロメリット酸（ＰＭＤＡ）０．１０モルを徐々に添加し反応させた。その後約２時間室温で攪拌を続け重合反応を行なった。褐色透明の粘稠なポリイミド前駆体溶液が得られた。
【００４１】
合成例２
温度計、塩化カルシウム管、攪拌棒及び窒素吸込口を取り付けた３００ｍｌの４つ口フラスコに毎分２００ｍｌの窒素を流しながら、パラフェニレンジアミン（ＰＤＡ）０．０８モル、及び 4,4'-ジアミノジフェニルエーテル（ＤＡＰＥ）０．０２モルを２２０ｍｌのN-メチル−2-ピロリドン（ＮＭＰ）中に攪拌溶解させた。この溶液を水冷浴中で１０℃以下に冷却しながら、3,3',4,4'-ビフェニルテトラカルボン酸無水物を０．１０モルを徐々に添加し反応させた。その後約２時間室温で攪拌を続け重合反応を行なった。褐色透明の粘稠なポリイミド前駆体溶液が得られた。
【００４２】
合成例３
温度計、塩化カルシウム管、攪拌棒及び窒素吸込口を取り付けた３００ｍｌの４つ口フラスコに毎分２００ｍｌの窒素を流しながら、1,3-ビス（4-アミノフェノキシ）ベンゼン（ＴＰＥ−Ｒ）０．１０モルを２２０ｍｌのジメチルアセトアミド（ＤＭＡｃ）中に攪拌溶解させた。この溶液を水冷浴中で１０℃以下に冷却しながら、3,3',4,4'-ジフェニルスルホンテトラカルボン酸無水物（ＤＳＤＡ）０．１０モルを徐々に添加し反応させた。その後約２時間室温で攪拌を続け重合反応を行なった。黄色透明の粘稠なポリイミド前駆体溶液が得られた。
【００４３】
合成例４
温度計、塩化カルシウム管、攪拌棒及び窒素吸込口を取り付けた３００ｍｌの４つ口フラスコに毎分２００ｍｌの窒素を流しながら、 4,4'-ジアミノジフェニルエーテル（ＤＡＰＥ）０．１０モルを２２０ｍｌのジメチルアセトアミド（ＤＭＡｃ）中に攪拌溶解させた。この溶液を水冷浴中で１０℃以下に冷却しながら、3,3',4,4'-ベンゾフェノンテトラカルボン酸無水物（ＢＴＤＡ）０．１０モルを徐々に添加し反応させた。その後約２時間室温で攪拌を続け重合反応を行なった。黄色透明の粘稠なポリイミド前駆体溶液が得られた。
【００４４】
実施例１
市販のシリコーン離型処理ポリエステルフィルム上に合成例３で得られたポリイミド前駆体樹脂溶液を乾燥後の厚みが３μｍになるように塗布し１２０℃で乾燥後、合成例１で得られたポリイミド前駆体樹脂溶液を乾燥後の厚みが３５μｍになる様に塗布し１２０℃で５分乾燥した。この条件下で残存するＤＭＡｃ量は固形分あたり３０％であった。
【００４５】
更に市販の酸現像型アクリル系感光性樹脂（東京プロセス（株）製ＮＣＡＲ）を乾燥後の厚みが２０μｍになるように塗布後１１０℃で１分乾燥した。更にその上に保護フィルムとして厚さ１５μｍのポリエステルフィルムをラミネートし、離形ポリエステルフィルム／良接着性ポリイミド前駆体樹脂層／低熱膨張性ポリイミド前駆体樹脂層／感光性樹脂層／保護ポリエステルフィルム層の５層の積層体を得た。
【００４６】
この積層体の離型フィルムを剥がして良接着性ポリイミド前駆体樹脂層が回路と接触するように予め回路加工しておいた無接着剤銅張積層板〔新日鐵化学（株）製商品名エスパネックス（圧延銅箔１８μｍ／ポリイミド３５μｍ）〕とラミネートした。回路は線幅３００μｍ／線間３００μｍの平行回路で、ラミネーター（大成ラミネーター（株）製ＳＴラミネーター８Ｂ−５５０ＩＤ）を用い、N-メチル−２−ピロリドン（ＮＭＰ）で霧吹きを用い回路表面を濡らした後、５０℃のロール温度で回路全面に２ｍ／分の速度でラミネートした。ポリイミド前駆体樹脂層はきれいに回路間に充填され気泡の巻き込みも見られなかった。
【００４７】
更にその保護フィルムに接触して３ｃｍ×１０ｃｍのパターンを有するネガフィルムを置き、ハイテック（株）製放電灯露光装置３０００ＮＥＬを用いて約１００ｍｍＮＪ／ｃｍ² の露光を行った後、離形フィルムを剥がした後で簡易縦型シャワー装置を用いて０．５％の乳酸水溶液で３０℃で水圧１ｋｇ／ｃｍ² で３０秒間現像した。
【００４８】
この感光層のみがパターン化された基板を水酸化ナトリウム１０％溶液を用いて簡易縦型シャワー装置により、液温４５℃で水圧１．５ｋｇ／ｃｍ² 、３５秒エッチング加工を行なった後、更に温水により液温４５℃で水圧１．５ｋｇ／ｃｍ² 、３５秒エッチング加工を施したところ剥き出しとなっていたポリイミド前駆体樹脂層はきれいにエッチングされ除去されていた。しかし感光性樹脂が残っていた部分に何ら変化はなかった。
【００４９】
続いて１０％の乳酸水溶液を用いて３０℃で４０秒間水圧１．０ｋｇ／ｃｍ² シャワーにより、残っていた感光性樹脂層の除去を行ない、得られた基板を水洗後熱風オーブン中で１３０℃１０分熱処理を行なった後、１６０、２００、２５０、３００℃で各２分間引続き熱処理した。
【００５０】
得られたフレキシブルプリント基板は絶縁層として２８μｍのポリイミド層を有し、その断面を顕微鏡で観察したところ、回路を均一な厚みで空隙なく覆っていた。また基板の外観は極めて良好な平面性を有していた。特性としては耐ハンダ性は３５０℃の高温まで耐え、また回路にそって手で折り曲げても切れたりせず、高い機械的特性を有していた。
【００５１】
更に前述の加工精度を判定するパターンを用いて、その加工精度を評価したところ、１００μｍの円形まできれいに加工されており、カバーレイフィルムの打抜きの加工精度よりはるかに優っていた。この絶縁樹脂層の熱膨張係数を別途調べたところ、２．０×１０^-5／℃であった。更に銅箔部分の接着力を測定したところ０．５ｋｇ／ｃｍの十分な接着力を有し、基板のポリイミドフィルムとは剥離不能であった。手動により回路を１０回折り曲げても剥離は皆無であった。
【００５２】
実施例２
合成例４で得たポリイミド前駆体樹脂溶液を、実施例１において合成例３の樹脂の代わりに用いて同様にして加工、評価を行なった。耐ハンダ性は３３０℃で折り曲げ性も良好であり、基板の平面性も優れていた。また加工精度も同様に１００μｍであった。熱膨張係数は２．２×１０^-5／℃であった。また回路部分との接着力は０．４ｋｇ／ｃｍの接着力を有し、基板のポリイミドフィルムとは剥離不能であった。手動により回路を１０回折り曲げても剥離は皆無であった。
【００５３】
実施例３
合成例２で得たポリイミド前駆体樹脂溶液を、実施例１において合成例１の樹脂の代わりに用いて同様にして加工、評価を行なった。ただしエッチング条件は約３倍の時間をかけて実施した。耐ハンダ性は３３０℃で折り曲げ性も良好であったが、基板の平面性は３ｃｍ×１０ｃｍのパターンで実験台上で１０ｍｍ程度のコーナーの立ち上がりがあった。しかし使用には差し支えの無いレベルである。加工精度は同様に１００μｍであった。熱膨張係数は２．８×１０^-5／℃であった。銅箔部分との接着力は０．５ｋｇ／ｃｍであり、基板のポリイミドフィルム面とは剥離不能であり、回路を手動で１０回折り曲げても剥離は皆無であった。
【００５４】
比較例１
実施例１において、合成例３の樹脂を用いずに積層体を形成後、同様の評価を行った。他の特性は同等であったが、銅箔との接着力が０．１ｋｇ／ｃｍ以下であり、基板を手動により１０回程折り曲げたところ界面での剥離が見られた。
【００５５】
比較例２
実施例３において、合成例３の樹脂を用いずに積層体を形成後、同様の評価を行った。他の特性は同等であったが、銅箔との接着力が０．１ｋｇ／ｃｍ以下であり、基板を手動により１０回程折り曲げたところ界面での剥離が見られた。
【００５６】
比較例３
実施例１において合成例１の樹脂を塗布後、１３０℃で１５分かけて乾燥し、以下同様の工程を経て積層体を得た。この時残存するＤＭＡｃを測定したところ５％であった。この積層体を用いて加工評価を行ったが、基板にラミネート時に回路に未充填部が発生し、またアルカリ／温水のエッチング時にエッチング不良部が多発した。
【００５７】
比較例４
実施例１において、アルカリエッチング後の温水エッチングを行わずに、アルカリエッチングのみで液温４５℃で水圧１．５ｋｇ／ｃｍ² で行ったところ、樹脂層がすべてエッチングされるまでに５分間もの時間が必要であった。
【００５８】
【発明の効果】
本発明の積層体は加工精度が高くかつ信頼性に優れた回路の絶縁保護層を極めて容易に提供しうるものである。[0001]
[Industrial application fields]
The present invention relates to an insulating protective material for a circuit board.
[0002]
[Prior art]
As conventional insulation protection methods for circuit boards, a method of protecting with an ink using screen printing (Japanese Patent Laid-Open No. Sho 62-263692) and a method of laminating a film with an adhesive called a coverlay film (Japanese Patent Laid-Open No. Sho 63-110224). No. Gazette) has already been implemented.
[0003]
The former is generally composed of a resin having no heat resistance, and since it is provided using a screen, there is a face that cannot cope with recent fine patterns due to its printing accuracy. Even in the latter, the use of a polyimide film with excellent heat resistance is superior in terms of reliability, but the processing process requires a complicated process of punching with a mold and then laminating with a hot press, and Similarly, there is a problem that it is difficult to cope with the fine pattern due to the low punching accuracy.
[0004]
On the other hand, a method of patterning by directly applying polyimide resin on the circuit by various methods and then etching with chemicals has been implemented, but in this case, dangerous chemicals such as hydrazine and ethylenediamine are used. There is a problem that it takes a long time to etch.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide an insulating protective material for a circuit board that is excellent in reliability, processing accuracy, and workability.
[0006]
[Means for solving the problems]
  That is, the present invention relates to an insulating protective film for a circuit comprising at least a photosensitive resin layer and a polyimide precursor resin layer.The polyimide precursor resin layer is 3 × 10 after curing ^-Five At least two layers of a low thermal expansion precursor resin layer to be a low thermal expansion resin layer having the following thermal expansion coefficient and a good adhesive precursor resin layer to be a better adhesive resin layer than the low thermal expansion resin layer after curing Insulating protective film characterized by havingIt is.
  In addition, this insulation protective film means the film for insulation protection of a circuit, and since it is a film which has a laminated structure, it is also called a laminated body. In addition, the low thermal expansion resin and the good adhesive resin mean a polyimide resin after curing (after imidization), but the explanation of the precursor layer that gives such polyimide resin is simplified in the range that does not cause misunderstanding. For the purpose, it is also referred to as a low thermal expansion resin layer and a good adhesive resin layer. Further, the good adhesive resin is a resin for improving the adhesiveness with the substrate, and has higher adhesiveness than the low thermal expansion resin.
[0007]
Any structure can be selected as the photosensitive resin layer, and any of a negative type and a positive type can be used. Photosensitive resins usually have an ultraviolet reaction type, an electron beam reaction type, and the like, and are composed of a base oligomer, a reactive diluent, a photoinitiator, a photosensitizer, a pigment, a polymerization inhibitor, and the like. Examples of the base oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate.
[0008]
In particular, the photosensitive resin is preferably an ultraviolet curable acrylic resin in terms of alkali resistance and water penetration resistance during etching of the polyimide precursor resin layer. Particularly preferred is an acrylic photosensitive resin that can be developed and peeled off with an acid. The thickness is preferably from 2 μm to 100 μm, and if it is less than that, the processing accuracy is high, but the film strength is insufficient and problems such as peeling are likely to occur when the polyimide precursor resin layer is etched. If the thickness exceeds 100 μm, the strength is high and the reliability is high, but the processing accuracy is lowered and the cost becomes high.
[0009]
The polyimide precursor resin is synthesized by reacting a diamine compound and an acid anhydride compound in a polar solvent at 0 to 200 ° C. In this case, if an imidization reaction occurs, the solubility is lowered, and the etching time becomes longer during patterning, which is not preferable.
[0010]
Examples of polar solvents include N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), dimethyl sulfate, sulfolane, butyrolactone, cresol, phenol, halogenated phenol, Examples include cyclohexanone, dioxane, tetrahydrofuran, and diglyme.
[0011]
Diamine compounds include p-phenylenediamine, m-phenylenediamine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, diaminotoluene, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1, 2-bis (anilino) ethane, diaminodiphenylsulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenyl sulfide, 2,2-bis (p-aminophenyl) propane, 2,2-bis (p-aminophenyl) hexafluoro Propane, 1,5-diaminonaphthalene, diaminotoluene, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) benzene, 4,4 '-(p-aminophenoxy Phenyl, diaminoanthraquinone, 4,4'-bis (3-aminophenoxyphenyl) diphenylsulfone, 1,3-bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluoropropane, 1,5-bis (Anilino) decafluoropropane, 1,7-bis (anilino) tetradecafluoropropane, the following general formula
[Chemical Formula 3]

(However, R in the formula₂And R_FourRepresents a divalent organic group, R₁And R_ThreeRepresents a monovalent organic group, and p and q represent integers greater than 1, and 2,2-bis [4- (p-aminophenoxy) phenyl] hexafluoropropane, 2,2 -Bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (2-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) ) -3,5-dimethylphenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) -3,5-ditrifluoromethylphenyl] hexafluoropropane, p-bis (4-amino-2) -Trifluoromethylphenoxy) benzene, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-3-trifluoromethylphenoxy) biphenyl, 4, 4'-bis (4-amino-2-trifluoromethylphenoxy) diph Nylsulfone, 4,4'-bis (4-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2,2-bis [4- (4-amino-3-trifluoromethylphenoxy) phenyl] hexafluoropropane, benzidine 3,3 ', 5,5'-tetramethylbenzidine, octafluorobenzidine, 3,3'-methoxybenzidine, o-tolidine, m-tolidine, 2,2', 5,5 ', 6,6'- There are diamines such as hexafluorotolidine, 4,4 "-diaminoterphenyl, 4,4" '-diaminoquaterphenyl, and diisocyanates obtained by reaction of these diamines with phosgene and the like.
[0012]
Examples of tetracarboxylic acid anhydrides and derivatives thereof include the following. In addition, although illustrated here as tetracarboxylic acid, these esterified products, acid anhydrides, and acid chlorides can of course be used. Pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, 3,3 ', 4,4'-diphenyl ether tetracarboxylic acid, 2,3,3', 4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 1,2,5,6 -Naphthalenetetracarboxylic acid, 3,3 ', 4,4'-diphenylmethanetetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) ) Hexafluoropropane, 3,4,9,10-tetracarboxyperylene, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane, 2,2-bis [4- (3,4 -Dicarboxyphenoxy) phenyl] hexafluoropropane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid and the like. Also included are trimellitic acid and its derivatives.
[0013]
Further, it can be modified with a compound having a reactive functional group to introduce a crosslinked structure or a ladder structure. For example, there are the following methods.
(A) A pyrrolone ring, an isoindoloquinazolinedione ring, or the like is introduced by modification with a compound represented by the following general formula (3).
[Formula 4]

[However, R in the formula_FiveRepresents an aromatic residue having a 2 + X valence (X is 1 or 2), and Z represents —NH₂Group, -CONH₂Group or -SO₂NH₂A substituent selected from the group which is ortho to the amino group. ]
(B) Modification with a derivative of amine, diamine, dicarboxylic acid, tricarboxylic acid or tetracarboxylic acid having a polymerizable unsaturated bond to form a crosslinked structure at the time of curing. As the unsaturated compound, maleic acid, nadic acid, tetrahydrophthalic acid, ethynylaniline and the like can be used.
(C) Modification with an aromatic amine having a phenolic hydroxyl group or carboxylic acid to form a crosslinking agent capable of reacting with the hydroxyl group or carboxyl group.
[0014]
In the present invention, the polyimide precursor thus obtained is provided in the form of a film in contact with the photosensitive resin layer. The thermal expansion coefficient of the entire resin layer after curing is 3 × 10.^-Five/ ° C. or less is preferable. Especially when it is provided on a flexible circuit such as a flexible printed circuit board, the thermal expansion coefficient is 3 × 10.^-FiveIf it exceeds / ° C., the circuit will be warped during cooling after high-temperature heat treatment such as imidization reaction, which is likely to cause practical problems.
[0015]
In the present invention, it is necessary that the polyimide precursor resin layer has a structure of at least two layers of a low thermal expansion resin layer and a good adhesive resin layer.
[0016]
The low thermal expansion resin layer is 3 × 10 after curing^-FiveIt is preferable to have a coefficient of thermal expansion of less than / ° C. The low thermal expansion resin layer is preferably a polyimide precursor having a repeating unit represented by the following general formula (1) or general formula (2), having a small thermal expansion coefficient and excellent mechanical properties such as flexibility. Yes.
[Chemical formula 5]

[0017]
In addition to these repeating units, for the purpose of controlling the thermal expansion coefficient or adjusting the mechanical properties, it is also possible to copolymerize or blend using the above-mentioned compounds and the like. In addition, for the purpose of improving various properties, it is also possible to use a mixture of inorganic, organic or metal powders, fibers, chopped strands and the like. Further, an additive such as an antioxidant or the like or a silane coupling agent can be added for the purpose of improving adhesiveness in order to prevent circuit oxidation during curing. It is also possible to blend different polymers for the purpose of improving flexibility or improving flowability and adhesion.
[0018]
A good adhesive resin layer is indispensable for improving the adhesion to the substrate, and if necessary, a three-layer structure with a low thermal expansion resin layer sandwiched between them and pasted to a circuit, followed by further processing It is also possible to develop adhesiveness at the time of bonding with other members such as a reinforcing plate.
[0019]
The good adhesive resin referred to in the present invention can be obtained by mainly reacting the above aromatic tetracarboxylic acid having 16 or more carbon atoms or a derivative thereof with an aromatic diamine compound having 12 or more carbon atoms.
[0020]
In addition to these main structures, it is possible to copolymerize various diamines and tetracarboxylic acid compounds with the goal of improving various properties such as adhesion, heat resistance, and filling properties, and separately synthesized polyimide precursor resins. It can be blended. Further, for the same purpose, it is possible to blend different types of thermoplastic polymers, rubbers and the like into the highly adhesive resin layer so as to express higher adhesive force. It is useful to blend nitrile butadiene rubber or the like particularly when sufficient adhesion to the glossy surface of the copper foil is required. It is also possible to add an additive such as an antioxidant for the purpose of preventing circuit oxidation and resin deterioration, or adding inorganic particles for the purpose of controlling flowability and surface properties.
[0021]
The ratio of the thickness of the good adhesive resin layer and the low thermal expansion resin layer can be arbitrarily set, but in general, the good adhesive resin layer obtained from the aromatic tetracarboxylic acid and the aromatic diamine is thermally expanded. The coefficient is 5 × 10^-FiveSince the temperature is higher than / ° C., it is not preferable that the layer is too thick because the resulting substrate warps.
[0022]
Moreover, it is preferable that this multilayer polyimide precursor resin layer contains 10 parts or more of organic solvents, and if it is less than that, the filling property to the circuit becomes insufficient, and bubbles are likely to be formed in the uneven portions. As the organic solvent, the above-mentioned aprotic polar solvents are preferable, and examples thereof include dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethylsulfoxide.
[0023]
The thickness of the polyimide precursor resin layer is preferably 2 μm to 300 μm, and if it is less than that, the reliability of circuit insulation is poor, and mechanical properties such as bending are low. If it exceeds 300 μm, a deterioration reaction is likely to occur during the imidization reaction, which is not preferable.
[0024]
The polyimide precursor thus obtained is brought into contact with the photosensitive resin layer to form a layer, and the formation method can be any method. As a method having better workability, a photosensitive resin is applied on a release film, and then a polyimide precursor resin solution is applied. Alternatively, the photosensitive resin solution can be applied after applying the polyimide precursor resin solution on the release film.
[0025]
Similarly, any method can be used for forming the polyimide precursor resin layer in multiple layers. However, sequential coating is preferable in view of the thickness accuracy, and reverse coating, knife coating are preferable. And die coating.
[0026]
It is also possible to protect the resin layer from dust by attaching a protective film as necessary.
[0027]
General film such as polyester film, polypropylene film, polyimide film, polyethylene film, and polyvinyl chloride film can be selected as the release film, and a release agent such as a silicone compound is used on the surface to increase the release property. A film coated with is more preferred.
[0028]
As the protective film, the above-mentioned film alone or a film coated with an adhesive if necessary is used.
[0029]
Drying of the polyimide precursor resin solution after coating can be selected within a range that does not cause deterioration of the photosensitive resin or the release film, but is preferably 180 ° C. or lower. If the temperature is exceeded, an imidization reaction occurs, and the flowability of the resin is lowered during the subsequent lamination to the circuit, so that the filling property is lowered, or the etching time becomes longer during patterning, which is not preferable.
[0030]
The laminated body thus obtained is laminated so that the polyimide precursor resin layer is in contact with a circuit board on which an arbitrary circuit pattern is drawn. The circuit board can be any circuit board such as a hard substrate such as glass epoxy or a flexible printed circuit board using a polyimide film, but the polyimide precursor resin layer needs to be cured at a high temperature to form a protective film. Therefore, a circuit board excellent in heat resistance such as a glass / maleimide hard board or an adhesive-free flexible printed board is more preferable.
[0031]
As a lamination method, a hot press machine or a roll-to-roll laminator can be used. At this time, it is more preferable to heat at 200 ° C. or lower in order to increase the filling property of the resin. In order to further improve the adhesion to the substrate, an immersion liquid such as an organic solvent such as the aforementioned aprotic polar solvent may be used for the interface.
[0032]
Next, in order to process the polyimide precursor resin layer as an insulating layer into an arbitrary shape, an arbitrary negative pattern or positive pattern is directly superimposed on the release film or the photosensitive resin layer, and exposure is performed. Further, after developing the photosensitive resin, the polyimide precursor is etched with an alkaline solution. It is also possible to heat to increase the speed during etching. At that time, if etching with warm water is used after alkali etching, etching is performed more effectively. Finally, the remaining photosensitive resin layer is peeled off to obtain a patterned polyimide precursor insulating resin layer.
[0033]
The circuit thus obtained is subjected to high-temperature heat treatment in order to perform a curing reaction that is an imidization reaction. The maximum heat treatment temperature is 200 ° C. or higher, more preferably 250 ° C. or higher. If the curing temperature is less than 200 ° C., the heat resistance and chemical resistance are inferior. Heating can be performed by either batch heat treatment using a hot air oven or heating of a roll-to-roll. Further, it is more preferable to carry out in an inert atmosphere because the oxidation of the circuit is suppressed.
[0034]
Although it is possible to perform insulation protection of any circuit using the laminate of the present invention, an ideal flexible printed wiring board in which the insulator is all polyimide by combining with an adhesive-free copper-clad laminate in particular. Can be made.
[0035]
It is also possible to fabricate a multilayer wiring board by sequentially processing the laminate of the present invention and plating. The multilayer wiring board obtained in this way has features such as the need for drilling or the like, flattening and thinning of the circuit, and low dielectric constant, and an ideal multilayer wiring board can be obtained.
[0036]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, of course, this invention is not limited to this.
[0037]
The coefficient of thermal expansion was measured using a thermomechanical analyzer (TMA) using a sample in which the imidization reaction had been sufficiently completed. The temperature was raised to 250 ° C, cooled at 10 ° C / min, and the average heat from 240 ° C to 100 ° C. The expansion coefficient was calculated and determined.
[0038]
For solder resistance, a circuit left at 76% RH for 24 hours was immersed in a solder bath for 1 minute, and the highest temperature at which swelling and peeling did not occur was examined in increments of 10 ° C.
[0039]
The processing accuracy was determined based on the size of the diameter having a good shape visually by etching the polyimide precursor resin layer using different circular patterns with a diameter of 10 μm.
[0040]
Synthesis example 1
2'-methoxy-4,4'-diaminobenzanilide (MABA) 0. 0, while flowing 200 ml of nitrogen per minute through a 300 ml four-necked flask equipped with a thermometer, calcium chloride tube, stir bar and nitrogen inlet. 07 mol and 0.03 mol of 4,4′-diaminodiphenyl ether (DAPE) were stirred and dissolved in 220 ml of dimethylacetamide (DMAc). While this solution was cooled to 10 ° C. or lower in a water-cooled bath, 0.10 mol of pyromellitic anhydride (PMDA) was gradually added and reacted. Thereafter, stirring was continued for about 2 hours at room temperature to carry out a polymerization reaction. A brown transparent viscous polyimide precursor solution was obtained.
[0041]
Synthesis example 2
While flowing 200 ml of nitrogen per minute into a 300 ml four-necked flask equipped with a thermometer, calcium chloride tube, stirring bar and nitrogen inlet, 0.08 mol of paraphenylenediamine (PDA) and 4,4′-diamino 0.02 mol of diphenyl ether (DAPE) was stirred and dissolved in 220 ml of N-methyl-2-pyrrolidone (NMP). While this solution was cooled to 10 ° C. or less in a water-cooled bath, 0.10 mol of 3,3 ′, 4,4′-biphenyltetracarboxylic anhydride was gradually added and reacted. Thereafter, stirring was continued for about 2 hours at room temperature to carry out a polymerization reaction. A brown transparent viscous polyimide precursor solution was obtained.
[0042]
Synthesis example 3
1,3-bis (4-aminophenoxy) benzene (TPE-R) 0 while flowing 200 ml of nitrogen into a 300 ml four-necked flask equipped with a thermometer, a calcium chloride tube, a stirring rod and a nitrogen suction port .10 mol was stirred and dissolved in 220 ml of dimethylacetamide (DMAc). While this solution was cooled to 10 ° C. or less in a water-cooled bath, 0.10 mol of 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic anhydride (DSDA) was gradually added and reacted. Thereafter, stirring was continued for about 2 hours at room temperature to carry out a polymerization reaction. A yellow transparent viscous polyimide precursor solution was obtained.
[0043]
Synthesis example 4
While flowing 200 ml of nitrogen into a 300 ml four-necked flask equipped with a thermometer, calcium chloride tube, stir bar and nitrogen inlet, 0.10 mol of 4,4′-diaminodiphenyl ether (DAPE) was added to 220 ml of dimethyl. Stirred and dissolved in acetamide (DMAc). While this solution was cooled to 10 ° C. or lower in a water-cooled bath, 0.10 mol of 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride (BTDA) was gradually added and reacted. Thereafter, stirring was continued for about 2 hours at room temperature to carry out a polymerization reaction. A yellow transparent viscous polyimide precursor solution was obtained.
[0044]
Example 1
The polyimide precursor resin solution obtained in Synthesis Example 3 was applied onto a commercially available silicone release-treated polyester film so that the thickness after drying was 3 μm, dried at 120 ° C., and then the polyimide precursor obtained in Synthesis Example 1 The body resin solution was applied so that the thickness after drying was 35 μm, and dried at 120 ° C. for 5 minutes. The amount of DMAc remaining under these conditions was 30% per solid.
[0045]
Further, a commercially available acid developing acrylic photosensitive resin (NCAR manufactured by Tokyo Process Co., Ltd.) was applied and dried at 110 ° C. for 1 minute so that the thickness after drying was 20 μm. Further, a polyester film having a thickness of 15 μm is laminated thereon as a protective film, and a release polyester film / good adhesive polyimide precursor resin layer / low thermal expansion polyimide precursor resin layer / photosensitive resin layer / protective polyester film layer A five-layer laminate was obtained.
[0046]
Non-adhesive copper-clad laminate [trade name, manufactured by Nippon Steel Chemical Co., Ltd.] that has been previously processed so that the release adhesive film of this laminate is peeled off and the good adhesion polyimide precursor resin layer is in contact with the circuit Espanex (rolled copper foil 18 μm / polyimide 35 μm)] was laminated. The circuit is a parallel circuit having a line width of 300 μm / line spacing of 300 μm, a laminator (ST Laminator 8B-550ID manufactured by Taisei Laminator Co., Ltd.) was used, and the circuit surface was wetted with N-methyl-2-pyrrolidone (NMP) using spraying. Thereafter, lamination was performed at a speed of 2 m / min on the entire circuit surface at a roll temperature of 50 ° C. The polyimide precursor resin layer was neatly filled between the circuits, and no bubble entrainment was observed.
[0047]
Further, a negative film having a pattern of 3 cm × 10 cm is placed in contact with the protective film, and about 100 mmNJ / cm using a discharge lamp exposure device 3000NEL manufactured by Hitech Co., Ltd.²After peeling off the release film, the water pressure was 1 kg / cm at 30 ° C. with 0.5% lactic acid aqueous solution using a simple vertical shower device.²And developed for 30 seconds.
[0048]
A substrate on which only the photosensitive layer is patterned is subjected to a simple vertical shower apparatus using a 10% sodium hydroxide solution at a liquid temperature of 45 ° C. and a water pressure of 1.5 kg / cm.²After 35 seconds of etching, the water temperature is 45 ° C. and the water pressure is 1.5 kg / cm.²The polyimide precursor resin layer that had been exposed after etching for 35 seconds was etched and removed cleanly. However, there was no change in the portion where the photosensitive resin remained.
[0049]
Subsequently, using a 10% aqueous lactic acid solution, the water pressure is 1.0 kg / cm at 40C for 40 seconds.²The remaining photosensitive resin layer was removed by showering, and the obtained substrate was washed with water and then heat-treated in a hot air oven at 130 ° C. for 10 minutes, and then at 160, 200, 250, and 300 ° C. for 2 minutes each. did.
[0050]
The obtained flexible printed circuit board had a 28 μm polyimide layer as an insulating layer, and its cross section was observed with a microscope. As a result, the circuit was covered with a uniform thickness without a gap. Further, the appearance of the substrate had very good flatness. As the characteristics, the solder resistance was resistant to a high temperature of 350 ° C., and it was not broken even if it was bent by hand along the circuit, and had high mechanical characteristics.
[0051]
Furthermore, when the processing accuracy was evaluated using the pattern for determining the processing accuracy, the processing accuracy was 100 μm, which was far superior to the processing accuracy of punching the coverlay film. When the thermal expansion coefficient of this insulating resin layer was separately examined, it was 2.0 × 10.^-Five/ ° C. Furthermore, when the adhesive force of the copper foil part was measured, it had a sufficient adhesive force of 0.5 kg / cm and was not peelable from the polyimide film of the substrate. Even if the circuit was bent 10 times by hand, no peeling occurred.
[0052]
Example 2
The polyimide precursor resin solution obtained in Synthesis Example 4 was processed and evaluated in the same manner using Example 1 instead of the resin of Synthesis Example 3. The solder resistance was 330 ° C., the bendability was good, and the flatness of the substrate was also excellent. The processing accuracy was also 100 μm. The coefficient of thermal expansion is 2.2 × 10^-Five/ ° C. The adhesive strength with the circuit part was 0.4 kg / cm, and it was not peelable from the polyimide film of the substrate. Even if the circuit was bent 10 times manually, no peeling occurred.
[0053]
Example 3
The polyimide precursor resin solution obtained in Synthesis Example 2 was processed and evaluated in the same manner using Example 1 instead of the resin of Synthesis Example 1. However, the etching conditions were about three times as long. The solder resistance was 330 ° C. and the bendability was good, but the flatness of the substrate was a 3 cm × 10 cm pattern with a corner rise of about 10 mm on the experimental table. However, it is at a level that is safe to use. The processing accuracy was similarly 100 μm. The coefficient of thermal expansion is 2.8 × 10^-Five/ ° C. The adhesive strength with the copper foil portion was 0.5 kg / cm, and it was not peelable from the polyimide film surface of the substrate, and there was no peeling even when the circuit was bent 10 times manually.
[0054]
Comparative Example 1
In Example 1, the same evaluation was performed after forming a laminated body without using the resin of Synthesis Example 3. Although the other characteristics were the same, the adhesive strength with the copper foil was 0.1 kg / cm or less, and when the substrate was bent manually about 10 times, peeling at the interface was observed.
[0055]
Comparative Example 2
In Example 3, the same evaluation was performed after the laminate was formed without using the resin of Synthesis Example 3. Although the other characteristics were the same, the adhesive strength with the copper foil was 0.1 kg / cm or less, and when the substrate was bent manually about 10 times, peeling at the interface was observed.
[0056]
Comparative Example 3
In Example 1, after applying the resin of Synthesis Example 1, it was dried at 130 ° C. for 15 minutes, and a laminate was obtained through the same steps. The DMAc remaining at this time was measured and found to be 5%. Processing evaluation was performed using this laminate, but unfilled portions were generated in the circuit during lamination on the substrate, and defective etching portions were frequently generated during etching of alkali / hot water.
[0057]
Comparative Example 4
In Example 1, without performing the hot water etching after the alkali etching, the water pressure is 1.5 kg / cm at the liquid temperature of 45 ° C. only by the alkali etching.² As a result, it took 5 minutes to etch all of the resin layer.
[0058]
【The invention's effect】
The laminate of the present invention can provide an insulating protective layer of a circuit with high processing accuracy and excellent reliability very easily.

Claims (9)

Low thermal expansion in which the polyimide precursor resin layer becomes a low thermal expansion resin layer having a thermal expansion coefficient of 3 × 10 ⁻⁵ or less after curing in a circuit insulation protection film comprising at least a photosensitive resin layer and a polyimide precursor resin layer An insulating protective film comprising at least two layers of an adhesive precursor resin layer and a highly adhesive precursor resin layer that becomes a better adhesive resin layer after curing than a low thermal expansion resin layer . The insulating protective film according to claim 1, wherein the photosensitive resin layer is an ultraviolet curable acrylic resin. 3. The insulating protective film according to claim 1, wherein one surface of the insulating protective film is a good adhesive precursor resin layer . The insulation protective film according to claim 1, wherein the cured polyimide precursor resin layer has a thermal expansion coefficient of 3 × 10 ⁻⁵ or less . The low thermal expansion precursor resin layer has the following general formula (1)

The insulating protective film according to claim 1, wherein the insulating protective film has repeating units of: The low thermal expansion precursor resin layer has the following general formula (2)

The insulating protective film according to claim 1, wherein the insulating protective film has repeating units of: A wiring board subjected to insulation protection processing using the insulation protective film according to claim 1 . A multilayer wiring board obtained by sequentially performing an insulating protection process using the insulating protective film according to any one of claims 1 to 6 and a process of forming a circuit thereon. The insulating protective film of the circuit according to any one of claims 1 to 6 is laminated so that the good adhesive precursor resin layer existing on the surface of the polyimide precursor resin layer is in contact with the circuit, and the photosensitive resin layer is selected. A method for producing a wiring board having an insulating protective film, wherein the exposed polyimide precursor resin layer is exposed to light, developed, and exposed to alkali, and then etched with warm water.