JP4742200B2 - Polyimide laminate for wiring boards - Google Patents

Description

（式中、Ｒ₁は下記式（２）で表される少なくとも２個のエーテル結合を有する２価の芳香族ジアミノ化合物残基を示し、Ｒ₂は４価の酸二無水物残基を示す。）
【化４】

ここで、式（２）のＸは、１以上の芳香環を含む２価の有機基である。
【００１１】
また、本発明は、金属層(M)が二層以上の多層構造をなし、その第一層の金属層(Ms)がニッケル、クロム及びコバルトから選ばれる金属又はこれらの金属の合金から構成され、第一層の金属層(Ms)の上に構成される第二層（第二層が複数層からなる場合は少なくとも一層）が電解メッキ法で形成された銅又は銅合金からなる金属層である前記の配線基板用ポリイミド積層体である。そして、スパッタリング法により形成される第一層の金属層(Ms)の厚みが0.5〜10.0nmの範囲であることが有利である。
【００１２】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【００１３】
本発明の配線基板用ポリイミド積層体（以下、配線基板用積層体という。）は、ポリイミド層と金属層とを有する。金属層は、ポリイミド層の片面又は両面に設けられるが、その少なくとも１層はスパッタリング法によってポリイミド層（PI）上に形成された金属層（Ms）を含む金属層（M）である。ここで、個々の前記ポリイミド層（PI）及び金属層（M）は、１層又は多層からなることができる。そこで、これらが多層の場合、両者が接するポリイミド層及び金属層となる層を、ポリイミド層（PI-a）及び金属層（Ms）として、他の層と区別する。もちろん、１層である場合は、区別する必要はない。
ポリイミド樹脂層は絶縁層としての役割も有するので、ポリイミド絶縁層と称することがある。ポリイミド層を構成するポリイミドは、一般的には、ジアミンとテトラカルボン酸二無水物とを反応させて得ることができる。なお、本発明において、ポリイミドとはポリイミド、ポリアミドイミド、ポリエーテルイミド、ポリエステルイミド、ポリシロキサンイミド、ポリベンズイミダゾールイミドなどの構造中にイミド基を有するポリマーからなる樹脂をいう。
【００１４】
ポリイミド層が多層構造をとる場合、ポリイミド層は、スパッタリング法により形成される金属層（M_S）と接するポリイミド層（PI-ａ）と、金属層（M_S）とは接さないポリイミド層（PI-ｃ）とに大別される。そして、本発明では、ポリイミド(PI-ａ層)に特定のポリイミドから得られるポリイミド層を適用する。
【００１５】
ポリイミド絶縁層が複数層からなる場合、金属層（M_S）と接しないポリイミド層（PI-ｃ）は特に限定されず、公知のポリイミドを用いることができる。好ましくは、熱膨張係数が、30×10^-6（1/K）以下であるポリイミドである。このようなポリイミド層は、特開平１-244841号公報等に示されているように既に知られており、これらを適宜使用できる。
【００１６】
スパッタリング法により形成される金属層（M_S）と接するポリイミド層（PI-ａ）には、上記一般式(1)に示すポリイミド構造単位を50モル％以上含有するポリイミドを用いることが必要であり、この構造単位を80モル％以上含有することがより好ましい。一般式(1)の構造単位となるジアミン成分と酸二無水物成分は、各々単独でも、２種以上を併用することもできる。ここで用いられるポリイミド樹脂は、一般式(１)で表されるポリイミド構造単位以外の単位を５０モル％以下の範囲で含有させてもよい。このように一般式(1)以外で表される構造単位を含有させることにより用途に応じた諸性能の微調整が可能である。なお、ポリイミド樹脂は、一般式(1)で表される構造単位を50モル％以上含有すればよく、共重合ポリイミド樹脂に限らず、このポリイミド樹脂を主成分とするポリイミド樹脂組成物であってもよい。
【００１７】
一般式(1)において、Ｒ₁は上記式(2)で表される少なくとも２個のエーテル結合を有する２価の芳香族ジアミノ化合物から生じる2価の残基を示し、Ｒ₂は酸二無水物から生じる4価の残基を示す。式(2)で示される2価の基の中でも、下記式(3) で示される基が好ましい。
【００１８】
【化５】

【００１９】
式(2)及び式(3)において、Ｘは2価の有機基であるが、１以上の芳香環を含む2価の有機基であることが好ましい。Ｘの好ましい具体例としては、フェニレン基、ビフェニレン基、-Ar-Y-Ar-（Arはフェニレン基であり、Yは炭素数1〜6のアルキレン若しくはアルキリデン基、O、S、SO、SO₂又はCO等の2価の基）で表される基があり、より好ましくは下記式(4)に示す3種類の基から選ばれるものが挙げられる。
【化６】

【００２０】
一般式（１）の構造単位を構成する好ましいジアミノ化合物としては、例えば2,2'-ビス[4-(4-アミノフェノキシ)フェニル]プロパン（BAPP）、1,3-ビス（4-アミノフェノキシ）ベンゼン（TPE-R）、4, 4'-ビス（4-アミノヒェノキシ）ビフェニル（BAPB）等が挙げられる。
【００２１】
一般式(1)において、Ｒ₂は４価の酸二無水物残基を示すが、好ましくは1環又は2環の芳香族テトラカルボン酸の酸二無水物残基であり、具体的には下記式(5)で表される４種類の基から選ばれる４価の基が好ましく挙げられる。
【化７】

【００２２】
一般式(1)の構造単位を構成する好ましい酸二無水物の具体例としては、無水ピロメリット酸（PMDA）、3,3'4,4'-ビフェニルテトラカルボン酸二無水物（BPDA）、3,3',4,4’-ベンゾフェノンテトラカルボン酸二無水物（BTDA）、3,3',4,4’-ジフェニルスルホンテトラカルボン酸二無水物（DSDA）等が挙げられる。
【００２３】
上述したようにポリイミド樹脂は、公知の方法で製造することができる。有利には、溶媒中で、ジアミン成分及び酸二無水物成分をほぼ等モルの割合で混合し、反応温度0〜200℃の範囲で、好ましくは0〜100℃の範囲で反応させて、ポリイミド樹脂の前駆体樹脂液を得て、更に、これをイミド化することによりポリイミド樹脂とする方法が挙げられる。反応に用いられる溶媒としては、Ｎ−メチルピロリドン(NMP)、ジメチルホルムアミド(DMF)、ジメチルアセトアミド(DMAc)、ジメチルスルフォキサイド(DMSO)、硫酸ジメチル、スルフォラン、ブチロラクトン、クレゾール、フェノール、ハロゲン化フェノール、シクロヘキサノン、ジオキサン、テトラヒドロフラン、ジグライム、トリグライムなどが挙げられ１種或いは２種以上を適宜選択して使用することができる。
【００２４】
配線基板用積層体を構成するポリイミド層は、１層のみからなる場合には、ポリイミド層（PI-ａ）の単層からなることになるが、ポリイミド層が２層以上からなる場合には、ポリイミド層（PI-ａ）とそれ以外のポリイミド層（PI-c）から構成されてもよい。このようなポリイミド層は、公知のポリイミドフィルムの製造方法によって製造することができる。
【００２５】
配線基板用積層体を、銅箔層／ポリイミド層（PI-ａ）／金属層(Ｍ_S）からなる層構成とする場合、その製造方法を例示すれば、銅箔を準備し、これにポリイミド前駆体溶液を塗工法により形成し、イミド化後、ポリイミド層上に金属層(M_S）をスパッタリング法により形成する方法が挙げられる。
【００２６】
次に、ポリイミド層に低熱膨張係数のポリイミド層（PI-ｃ）を設けて銅箔層／ポリイミド層（PI-ｃ）／ポリイミド層（PI-a）／金属層(M_S）からなる積層体とするまでの製造例を以下に示す。まず、銅箔上にポリイミド層（PI-ｃ）となるポリイミド前駆体状態の溶液を直接塗布し、適当な方法で予備乾燥する。次に、この上にポリイミド層（PI-a）となるポリイミド前駆体状態の溶液を塗布し、適当な方法で予備乾燥する。そして、所定の温度に設定可能な熱風乾燥炉の中で、一定時間静置させるか、あるいは、乾燥炉エリア範囲内を連続移動させ所定の乾燥硬化時間を確保させることで高温での熱処理（200℃以上）を行い、イミド化する方法が一般的である。かかる熱処理工程では、銅箔の酸化を防ぐことを目的として、減圧下、還元性気体雰囲気下あるいは還元性気体雰囲気減圧下にて行うことが好ましい。その後、ポリイミド層（PI-a）上に金属層(M_S）をスパッタリング法により形成する方法が挙げられる。
【００２７】
このように、ポリイミド層を複数層とする場合、異なる構成成分からなるポリイミド層の上に他のポリイミドを順次塗布して形成することができる。ポリイミド樹脂層が３層以上からなる場合、同一の構成のポリイミド樹脂を２回以上使用してもよい。
【００２８】
金属層（M）が多層である場合は、ポリイミド層上にスパッタリング法によって、金属層（M_S）を設け、その上に電解メッキ法等によって形成される第二層の金属層を設けることができる。ポリイミド層には、ポリイミドをフィルム化してその片面又は両面に金属層（M）を後記する手法で積層することも可能であるし、上記した方法で、ポリイミドの片面に金属箔を有する積層体を製造した後、金属層（M）を後記する手法で積層することも可能である。
本発明による配線基板用積層体の構成例としては、下記Ｉ）〜III）の態様を例示することができる。なお、下記において、ポリイミド層はPIと、金属箔はFと、スパッタリング法による金属層（M_S）を有する金属層をMとして表した。
Ｉ ） PI／M
II ） F／PI／M
III） M／PI／M
【００２９】
ここで、ポリイミド層は、単層のポリイミド層（PI-ａ）からなる場合と、ポリイミド層（PI-ａ）とポリイミド層（PI-ｃ）との多層構造が考えられるが、金属層（M_S）と接する層には、ポリイミド層（PI-ａ）が適用される。なお、上記III）の態様では、ポリイミド層の両面が金属層（M_S）と接しているが、接する層の少なくとも１層、好ましくは２層にポリイミド層（PI-ａ）が適用される。また、ポリイミド層（PI-ａ）とポリイミド層（PI-ｃ）は単層である必要はなく、多層であってもよい。例えば、ポリイミド層（PI-ａ）をａで表し、ポリイミド層（PI-ｃ）をｃで表せば、a/c、a/c/a、c/c/aのようなポリイミド層が例示される。同様に金属層のMは、ポリイミド層（PI-ａ）と接する第一層の金属層（M_S）を、M_S、その上に形成される金属層をM2、更にその上に形成される金属層をM3、M4とすれば、M_S、M_S/M2、M_S/M2/M3等の層構造がある。ここで、M2以降の金属層をまとめて第二層の金属層という。したがって、第二層の金属層は複数の層からなっていてもよく、それらはスパッタリング法によって形成されたものでも、メッキ法で形成されたものでもよい。好ましくは、第二層の金属層の厚みの過半、より好ましくは80％以上が電解メッキ法で形成された銅又は銅合金であることである。
【００３０】
金属層（M）は一層であってもよいが、二層構造をなし、ポリイミド層に接する第一層の金属層（Ms）がニッケル、クロム、コバルトから選ばれる少なくとも１種類以上の金属から構成され、更にその上に設けられる第二層が銅から構成されることが好ましい。ここで、金属というときは、その金属を主成分とする合金を含む意味に解釈される。
【００３１】
二層構造を形成する際、まずはスパッタリング法により１種類の金属又は２種類以上の金属の合金をポリイミド樹脂層に積層して金属層（Ms）とし、これを下地層として第二層としての銅層を積層したものが好ましい。金属層（Ms）とするための金属としては、ニッケル、クロム、コバルトから選ばれる少なくとも１種類の金属又はこれらを主成分とする合金が好ましい。
【００３２】
スパッタリング法により形成される金属層においてポリイミドと接する第一層の金属層（Ms）の厚みは、0.5〜10nmであることが好ましく、より好ましくは2.0〜5.0nmである。0.5nm未満であると、金属層とポリイミド層との接着強度が低下し、高温高湿環境に暴露された後の接着強度も急激に悪化し、信頼性を保つことが出来なくなる。また、10nmより厚いと配線のファインパターン加工性に劣る可能性が高くなってしまう。
【００３３】
第二層の金属層としては銅層が好ましく、この第二層はスパッタリング法又は電解メッキ法によって形成され、複数層からなってもよい。有利には、スパッタリング法により電解メッキ法での電流密度に耐えうる銅層を形成し、後に電解メッキ法にて所定の厚みの銅箔薄膜を形成することがよい。
第二層を、スパッタリング法と電解メッキ法で形成する場合、スパッタリング法での金属第二層の厚みは10nm以上であることが好ましく、より好ましくは100nm以上である。厚すぎるとコストが高くなりすぎ、薄すぎるとこの後の電解メッキ成膜時に高抵抗となり焼き切れ等の不良発生が生じ易くなってしまう。更に、スパッタリング法にて形成された金属層上に電解メッキ法により銅層を積層する。電解メッキ法での金属層の厚みは、任意の厚みに設定することが可能である。
【００３４】
本発明ではスパッタリング法として、ＤＣ（直流）２極スパッタリング、ＤＣ３極スパッタリング、ＲＦ（高周波）スパッタリング、ＤＣマグネトロンスパッタリング、ＲＦマグネトロンスパッタリング、イオンビームスパッタリングなどを利用することが可能である。好ましくはＤＣマグネトロンスパッタリング法であり、装置の簡易性・スパッタされるターゲット材料の高い利用効率・成膜安定性などから有利である。
【００３５】
スパッタリングではヘリウム、ネオン、アルゴン、クリプトン、キセノン、窒素などのガス種が使用可能であるが、ガス入手が容易であり成膜時に金属との反応を起さないアルゴンガスが一般的に使用されている。
【００３６】
スパッタリングの前工程としてフィルム化されたポリイミドの含有水分等を制御するために乾燥炉にて加熱してもよい。効率よく乾燥を行うためには、真空中で室温〜200℃の温度で加熱するとよい。
【００３７】
電解メッキ法として硫酸銅浴、ピロリン酸銅浴、シアン化銅浴などを利用することが可能である。好ましくは硫酸銅浴での電解メッキ法であり、メッキ浴組成の分解物発生が少なく液管理が容易・廃水処理の簡易性などから有利ある。
また、メッキ膜の結晶粒子の微細化、光沢化、レベリング、膜厚の均一性などの目的のために添加剤を添加することも可能である。添加剤が陰極表面に吸着し、陰極表面の反応を妨害し、結晶の多核化が行われ、結晶の微細化、光沢化、レベリング向上、物性の向上、均一電着性の向上が期待できる。
【００３８】
【実施例】
以下、本発明を実施例により更に詳細に説明する。
まず、ポリイミドの合成例を示す。
【００３９】
合成例１
熱電対、攪拌機、窒素導入可能な反応容器に、DMAcを入れる。この反応容器を容器に入った氷水に浸けた状態で、反応容器に無水ピロメリット酸（PMDA）を投入し、その後、2,2'-ビス[4-(4-アミノフェノキシ)フェニル]プロパン（BAPP）を投入した。モノマーの投入総量が15wt%で、酸無水物とジアミンのモル比が1.03：1.0となるよう投入した。その後、更に攪拌を続け、反応容器内の温度が、室温から±5℃の範囲となった時に反応容器を氷水から外した。室温のまま3時間攪拌を続け、溶液粘度3,000cpsのポリアミック酸溶液aを得た。
【００４０】
合成例２
DMAcを入れた反応容器を氷水に浸け、これに無水ピロメリット酸（PMDA）を投入し、その後、1,3-ビス（4-アミノフェノキシ）ベンゼン（TPE-R）を投入した。モノマーの投入総量が15wt%で、酸無水物とジアミンのモル比が1.03：1.0となるよう投入した。その後、更に攪拌を続け、反応容器内の温度が、室温から±5℃の範囲となった時に反応容器を氷水から外した。室温のまま3時間攪拌を続け、溶液粘度3,200cpsのポリアミック酸溶液ｂを得た。
【００４１】
合成例３
DMAcを入れた反応容器を氷水に浸け、これに無水ピロメリット酸（PMDA）を投入し、その後、4, 4'-ビス（4-アミノヒェノキシ）ビフェニル（BAPB）を投入した。モノマーの投入総量が15wt%で、酸無水物とジアミンのモル比が1.03：1.0となるよう投入した。その後、更に攪拌を続け、反応容器内の温度が、室温から±5℃の範囲となった時に反応容器を氷水から外した。室温のまま3時間攪拌を続け、溶液粘度3,500cpsのポリアミック酸溶液cを得た。
【００４２】
合成例4
DMAcを入れた反応容器を氷水に浸け、これに無水ピロメリット酸（PMDA）を投入し、その後、4,4'-ジアミノフェニルエーテル（DAPE）を投入した。モノマーの投入総量が15wt%で、酸無水物とジアミンのモル比が1.03：1.0となるよう投入した。その後、更に攪拌を続け、反応容器内の温度が、室温から±5℃の範囲となった時に反応容器を氷水から外した。室温のまま3時間攪拌を続け、溶液粘度2,850cpsのポリアミック酸溶液ｄを得た。
【００４３】
合成例5
DMAcを入れた反応容器を氷水に浸け、これに無水ピロメリット酸（PMDA）を投入し、その後、4,4'-ジアミノ-2,2'-ジメチルビフェニル（DADMB）を投入した。モノマーの投入総量が15wt%で、酸無水物とジアミンのモル比が1.03：1.0となるよう投入した。その後、更に攪拌を続け、反応容器内の温度が、室温から±5℃の範囲となった時に反応容器を氷水から外した。室温のまま3時間攪拌を続け、溶液粘度3,750cpsのポリアミック酸溶液eを得た。
【００４４】
合成例6
DMAcを入れた反応容器を氷水に浸け、これに無水ピロメリット酸（PMDA）を投入し、その後、パラフェニレンジアミン（ＰＤＡ）を投入した。モノマーの投入総量が15wt%で、酸無水物とジアミンのモル比が1.03：1.0となるよう投入した。その後、更に攪拌を続け、反応容器内の温度が、室温から±5℃の範囲となった時に反応容器を氷水から外した。室温のまま3時間攪拌を続け、溶液粘度4000cpsのポリアミック酸溶液ｆを得た。
【００４５】
実施例１
銅箔として、三井金属鉱業株式会社製の銅箔（NA-VLP、18μm厚。以下、単に銅箔というときは、この銅箔をいう）を使用した。この銅箔上に合成例１で調製したポリアミック酸溶液aを塗布したのち、130℃で加熱乾燥し溶剤を除去した。この後、室温から280℃まで約４hrかけて熱処理しイミド化させ、合計厚み約40μmのポリイミド層が銅箔上に形成された片面銅張り積層体を得た。
【００４６】
この積層体をＤＣマグネトロンスパッタリング装置にセットし、ポリイミド面に金属薄膜を形成した。サンプルをセットした槽内は１×１０^-3Paまで減圧した後、アルゴンガスを導入し真空度を１×１０^-1Paとし、ＤＣ電源にてプラズマを発生した。このプラズマにてニッケル（99.99wt%）を3nmポリイミド上に成膜した。
ニッケル成膜後、同一雰囲気下にてニッケル上に銅（99.99wt%）を200nm成膜した。
更に、その銅スパッタ膜を電極として電解メッキ浴にて18μm厚の銅メッキ層を形成した。電解メッキ浴には硫酸銅浴（硫酸銅100g/L,硫酸220g/L,塩素40mg/L,アノードは含りん銅）を使用し、電流密度2.5A/dｍ²にてメッキ膜を形成した。メッキ後には十分な蒸留水で洗浄し乾燥を行った。
【００４７】
このようにして、銅箔／ポリイミド層／ニッケル層（M_S）／銅スパッタ層／電解メッキ銅層から構成される両面銅張り積層体を得た。ポリイミド層と、ニッケル層（M_S）と電解メッキ銅層を有する金属層（M)との接着強度等を評価するため、この両面銅張り積層体の銅箔側を塩化第二鉄により全面エッチングして片面銅張り積層体とし、電解メッキ銅層をフォトレジスト及び塩化第二鉄を用いてエッチング加工し、100μｍＷの回路パターンを得た。
【００４８】
得られたフレキシブル配線基板の常態ピール強度及び150℃大気雰囲気下に168ｈｒ暴露したあとのピール強度、121℃，100％ＲＨの環境に96ｈｒ暴露したあとのピール強度を、90°引き剥がし法により測定した。また、上記導体パターン形成後、ティンポジットLT-34（シプレーファースト社製）の無電解Ｓｎメッキ液にて70℃，3 min処理して0.5μｍメッキしたものについても上記同様の測定を実施した。
【００４９】
ポリイミドと金属間の接着強度は常態で１１００Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で１０５０Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で９５０Ｎ／ｍであり、良好な接着力と信頼性を有していた。またＳｎメッキ後の接着強度は常態で１０００Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で９５０Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で９００Ｎ／ｍであり、良好な接着力と信頼性を有していた。
【００５０】
実施例２
銅箔上に合成例２で調製したポリアミック酸溶液ｂを塗布した以外は実施例１と同様にして積層体の製造及び評価を行った。
ポリイミドと金属間の接着強度は常態で１０５０Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で９００Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で８５０Ｎ／ｍであり、良好な接着力と信頼性を有していた。またＳｎメッキ後の接着強度は常態で１０５０Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で９５０Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で９００Ｎ／ｍであり、良好な接着力と信頼性を有していた。
【００５１】
実施例３
銅箔上に合成例３で調製したポリアミック酸溶液ｃを塗布した以外は実施例１と同様にして積層体の製造及び評価を行った。
ポリイミドと金属間の接着強度は常態で１０００Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で９００Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で８５０Ｎ／ｍであり、接着力の信頼性を有していた。またＳｎメッキ後の接着強度は常態で１０００Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で９００Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で８００Ｎ／ｍであり、良好な接着力と信頼性を有していた。結果を表２、表３に示す。
【００５２】
比較例１
銅箔上に合成例４で調製したポリアミック酸溶液ｄを塗布した以外は実施例１と同様にして積層体の製造及び評価を行った。
ポリイミドと金属間の接着強度は常態で５００Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で３００Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で３００Ｎ／ｍであり、十分な接着力が得られなかった。またＳｎメッキ後の接着強度は常態で４５０Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で２５０Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で２５０Ｎ／ｍであり、十分な接着力が得られなかった。
【００５３】
比較例２
銅箔上に合成例５で調製したポリアミック酸溶液ｅを塗布した以外は実施例１と同様にして積層体の製造及び評価を行った。
ポリイミドと金属間の接着強度は常態で１５０Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で１００Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で５０Ｎ／ｍであり、十分な接着力が得られなかった。またＳｎメッキ後の接着強度は常態で１５０Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で８０Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で６０Ｎ／ｍであり、十分な接着力が得られなかった。
【００５４】
比較例３
銅箔上に合成例６で調製したポリアミック酸溶液ｆを塗布した以外は実施例１と同様にして積層体の製造及び評価を行った。
ポリイミドと金属間の接着強度は常態で２００Ｎ／ｍｍであり、１５０℃，１６８ｈｒ処理後で１５０Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で１００Ｎ／ｍであり、十分な接着力が得られなかった。またＳｎメッキ後の接着強度は常態で１５０Ｎ／ｍであり、１５０℃，１６８ｈｒ処理後で１２０Ｎ／ｍ、１２１℃，１００％，９６ｈｒ処理後で１００Ｎ／ｍであり、十分な接着力が得られなかった。
結果をまとめて表１及び表２に示す。
【００５５】
【表１】

【００５６】
【表２】

【００５７】
【発明の効果】
本発明によれば、常態での接着強度のみならず高温高湿下に暴露後の接着強度も高く、長期信頼性に優れた配線基板用ポリイミド積層体が得られる。このポリイミド積層体は可とう性も有しており携帯電話用ＣＯＦ用途等の配線基板材料に広く用いることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polyimide laminate for a wiring board, and more particularly, to a polyimide laminate for a flexible wiring board having excellent fine pattern workability of wiring, high adhesion between wiring and polyimide, and reliability. It is.
[0002]
[Prior art]
In recent years, COF (chip-on-film), in which an IC chip is directly mounted on a film-like substrate wiring used in mobile phone liquid crystal drivers, etc., has a narrower wiring pitch due to an increase in the amount of processing information and downsizing Is progressing. Therefore, demands for fine pattern workability and heat resistance for a polyimide laminate for a wiring board having a polyimide resin layer and a metal layer used as a substrate wiring material used therein are also increasing.
[0003]
Due to its manufacturing method and characteristics, current polyimide laminates for wiring boards are cast by coating polyimide on copper foil, laminating by thermocompression bonding polyimide film on copper foil, sputtering and electrolytic plating on polyimide film, etc. It is classified as a sputter plating method for forming a metal layer.
[0004]
In the sputter plating method, the metal layer thickness can be freely controlled by the electrolytic plating method, so the metal layer can be made thinner, and the smoothness of the interface between the polyimide and the metal layer is high, so the fine pattern forming ability is excellent. It is said that there is. However, since the polyimide laminate obtained by the manufacturing method using the sputter plating method has a smooth interface as described above, the anchoring effect cannot be expected in the adhesion between the polyimide and the metal, and the adhesion strength of the interface is low. There was a problem of insufficient expression.
[0005]
Thus, various studies have been made so far to improve the adhesion (adhesion) between the metal and the polyimide film, and the metal layer is directly deposited on the polyimide film by a method such as vacuum deposition, sputtering, ion plating, or copper plating. There has been proposed a polyimide-metal laminate in which is formed.
[0006]
For example, in JP-A-8-330728, on one or both sides of a polyimide film containing tin in the film, in the thickness direction directed inward from the film surface, a part or all of the deposited metal is mixed in the film, A flexible printed wiring board is shown in which a first vapor-deposited metal layer having a thickness in the range of 10 to 300 mm including the mixed layer is provided, and a second vapor-deposited layer made of copper is provided on the layer. In JP-A-11-268183, a metal oxide layer of 3 to 35 nm is formed by sputtering on a polyimide base material whose surface roughness is changed to 0.5 to 5 nm, and a metal layer is formed on the metal layer. The resulting polyimide-metal laminate is shown. JP-A-2002-172734 discloses a vacuum deposition method using one or more metals selected from the group consisting of nickel, nickel alloy, nickel compound, chromium, chromium alloy, and chromium compound on one or both sides of a polyimide film as an underlayer. A copper thin film layer having a thickness of 1000 to 5000 mm formed by a vacuum deposition method, an ion plating method or a sputtering method on the underlying layer, and formed in a thickness range of 10 to 300 mm by an ion plating method or a sputtering method. A polyimide / metal laminate is proposed in which a copper plating layer having a thickness of 3 to 35 μm formed by plating is laminated on the copper thin film layer.
[Patent Document 1]
JP-A-8-330728
[Patent Document 2]
Japanese Patent Laid-Open No. 11-268183
[Patent Document 3]
JP 2002-172734 A
[0007]
However, commercially available polyimide films such as Kapton V and Upilex S, which are mainly used in the above technology, have plasma treatment of the polyimide surface as a pretreatment for conductor formation by sputtering or the like because of the adhesion strength between metal and polyimide. It was necessary to sufficiently modify it to an appropriate range such as alkali or alkali. In the above technology, the measurement of adhesive strength in normal and high temperature / high humidity environments is performed using a circuit pattern with a width of 1 mm or more, and between the wiring / polyimide in a circuit pattern width of less than 1 mm that is actually used. It was difficult to say that the reliability of the adhesive strength was sufficiently reflected.
[0008]
[Problems to be solved by the invention]
The present invention has a good adhesion strength between a metal layer and a polyimide layer, maintains an excellent adhesion strength even after being exposed to a high-temperature and high-humidity environment, and is excellent in reliability. It aims at providing the formed polyimide laminated body for wiring boards. Another object of the present invention is to provide a polyimide laminate that has flexibility and can be applied to wiring board materials such as COF for mobile phones.
[0009]
[Means for solving the problems]
In order to solve the above-mentioned problems, the present inventors have examined, as a result of further investigation with a focus on the primary structure of the polyimide resin layer in contact with the metal layer, using a specific polyimide as the polyimide insulating resin layer, It has been found that the above problem can be solved by applying this to a polyimide resin layer for forming a metal layer by sputtering, and the present invention has been completed.
[0010]
  The present inventionA polyimide precursor resin solution is applied onto a copper foil, dried, imidized to form a polyimide layer, and a metal layer (Ms) is formed on the polyimide layer by a sputtering method. A wiring board polyimide laminate, wherein the metal layer on one side is a copper foil layer, and the metal layer on the other side is a metal layer (M) having a metal layer (Ms) formed by sputtering. Yes,The polyimide layer (PI-a) in contact with the metal layer (Ms) contains 50 mol% or more of a polyimide structural unit represented by the following general formula (1). .
[Chemical Formula 3]

(Wherein R₁Represents a divalent aromatic diamino compound residue having at least two ether bonds represented by the following formula (2);₂Represents a tetravalent acid dianhydride residue. )
[Formula 4]

  Here, X in the formula (2) isA divalent organic group containing one or more aromatic rings.
[0011]
In the present invention, the metal layer (M) has a multilayer structure of two or more layers, and the metal layer (Ms) of the first layer is composed of a metal selected from nickel, chromium and cobalt or an alloy of these metals. The second layer (or at least one layer when the second layer is composed of a plurality of layers) formed on the first metal layer (Ms) is a metal layer made of copper or a copper alloy formed by electrolytic plating. It is a polyimide laminate for a wiring board as described above. The thickness of the first metal layer (Ms) formed by the sputtering method is advantageously in the range of 0.5 to 10.0 nm.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0013]
The polyimide laminate for a wiring board of the present invention (hereinafter referred to as a wiring board laminate) has a polyimide layer and a metal layer. The metal layer is provided on one side or both sides of the polyimide layer, at least one of which is a metal layer (M) including a metal layer (Ms) formed on the polyimide layer (PI) by a sputtering method. Here, each of the polyimide layer (PI) and the metal layer (M) may be composed of one layer or multiple layers. Therefore, when these are multi-layers, the polyimide layer and the metal layer that are in contact with each other are distinguished from other layers as a polyimide layer (PI-a) and a metal layer (Ms). Of course, in the case of one layer, it is not necessary to distinguish.
Since the polyimide resin layer also serves as an insulating layer, it may be referred to as a polyimide insulating layer. The polyimide constituting the polyimide layer can be generally obtained by reacting diamine and tetracarboxylic dianhydride. In the present invention, polyimide means a resin made of a polymer having an imide group in the structure such as polyimide, polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, polybenzimidazoleimide and the like.
[0014]
When the polyimide layer has a multilayer structure, the polyimide layer is a metal layer (M_S) In contact with the polyimide layer (PI-a) and metal layer (M_S) And a polyimide layer (PI-c) that does not contact. In the present invention, a polyimide layer obtained from a specific polyimide is applied to the polyimide (PI-a layer).
[0015]
When the polyimide insulation layer consists of multiple layers, the metal layer (M_SThe polyimide layer (PI-c) not in contact with the substrate is not particularly limited, and a known polyimide can be used. Preferably, the thermal expansion coefficient is 30 × 10^-6(1 / K) or less of polyimide. Such polyimide layers are already known as disclosed in JP-A-1-244841 and the like, and these can be used as appropriate.
[0016]
Metal layer formed by sputtering (M_S) In contact with the polyimide layer (PI-a), it is necessary to use polyimide containing 50 mol% or more of the polyimide structural unit represented by the general formula (1), and contains 80 mol% or more of this structural unit. It is more preferable. The diamine component and acid dianhydride component, which are structural units of the general formula (1), can be used alone or in combination of two or more. The polyimide resin used here may contain a unit other than the polyimide structural unit represented by the general formula (1) in a range of 50 mol% or less. Thus, by including the structural unit represented by other than the general formula (1), various performances can be finely adjusted according to the application. The polyimide resin only needs to contain 50 mol% or more of the structural unit represented by the general formula (1), and is not limited to the copolymerized polyimide resin, and is a polyimide resin composition mainly composed of this polyimide resin. Also good.
[0017]
In the general formula (1), R₁Represents a divalent residue generated from a divalent aromatic diamino compound having at least two ether bonds represented by the above formula (2), and R₂Indicates a tetravalent residue derived from an acid dianhydride. Of the divalent groups represented by the formula (2), groups represented by the following formula (3) are preferred.
[0018]
[Chemical formula 5]

[0019]
In the formulas (2) and (3), X is a divalent organic group, but is preferably a divalent organic group containing one or more aromatic rings. Preferable specific examples of X include a phenylene group, a biphenylene group, -Ar-Y-Ar- (Ar is a phenylene group, Y is an alkylene or alkylidene group having 1 to 6 carbon atoms, O, S, SO, SO₂Or a divalent group such as CO), more preferably a group selected from three types of groups represented by the following formula (4).
[Chemical 6]

[0020]
Preferred diamino compounds constituting the structural unit of the general formula (1) include, for example, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 1,3-bis (4-aminophenoxy) ) Benzene (TPE-R), 4,4′-bis (4-aminophenoxy) biphenyl (BAPB), and the like.
[0021]
In the general formula (1), R₂Represents a tetravalent acid dianhydride residue, preferably an acid dianhydride residue of a monocyclic or bicyclic aromatic tetracarboxylic acid, specifically represented by the following formula (5): A tetravalent group selected from four types of groups is preferred.
[Chemical 7]

[0022]
Specific examples of preferred acid dianhydrides constituting the structural unit of the general formula (1) include pyromellitic anhydride (PMDA), 3,3′4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA) and the like.
[0023]
As described above, the polyimide resin can be produced by a known method. Advantageously, the diamine component and the acid dianhydride component are mixed in a solvent in an approximately equimolar proportion and reacted at a reaction temperature in the range of 0 to 200 ° C, preferably in the range of 0 to 100 ° C. A method of obtaining a polyimide resin by obtaining a precursor resin liquid of a resin and imidizing the resin is further mentioned. Solvents used in the reaction include N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), dimethyl sulfate, sulfolane, butyrolactone, cresol, phenol, halogenated Phenol, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme and the like can be mentioned, and one or more can be appropriately selected and used.
[0024]
When the polyimide layer constituting the laminate for a wiring board is composed of only one layer, it is composed of a single layer of the polyimide layer (PI-a), but when the polyimide layer is composed of two or more layers, You may be comprised from a polyimide layer (PI-a) and the other polyimide layer (PI-c). Such a polyimide layer can be produced by a known method for producing a polyimide film.
[0025]
Laminate for wiring board is made of copper foil layer / polyimide layer (PI-a) / metal layer (M_S), A copper foil is prepared, and a polyimide precursor solution is formed thereon by a coating method. After imidization, a metal layer (M_S) By a sputtering method.
[0026]
Next, a polyimide layer (PI-c) having a low thermal expansion coefficient is provided on the polyimide layer, and a copper foil layer / polyimide layer (PI-c) / polyimide layer (PI-a) / metal layer (M_SA production example up to a laminate comprising First, a polyimide precursor solution to be a polyimide layer (PI-c) is directly applied on a copper foil, and preliminarily dried by an appropriate method. Next, a polyimide precursor solution to be a polyimide layer (PI-a) is applied thereon and preliminarily dried by an appropriate method. Then, in a hot air drying furnace that can be set to a predetermined temperature, it is allowed to stand for a certain period of time, or continuously moved in the drying furnace area range to ensure a predetermined drying and curing time (200 C. or higher) and imidizing is generally used. The heat treatment step is preferably performed under reduced pressure, in a reducing gas atmosphere or in a reducing gas atmosphere under reduced pressure for the purpose of preventing oxidation of the copper foil. After that, a metal layer (M_S) By a sputtering method.
[0027]
Thus, when making a polyimide layer into multiple layers, it can form by apply | coating another polyimide sequentially on the polyimide layer which consists of a different structural component. When the polyimide resin layer is composed of three or more layers, the polyimide resin having the same configuration may be used twice or more.
[0028]
When the metal layer (M) is a multilayer, the metal layer (M_S) And a second metal layer formed by electrolytic plating or the like can be provided thereon. It is also possible to laminate the polyimide layer as a film and laminate the metal layer (M) on one side or both sides of the polyimide layer by the method described later. After the production, the metal layer (M) can be laminated by a method described later.
Examples of the configuration of the laminate for a wiring board according to the present invention include the following aspects I) to III). In the following, the polyimide layer is PI, the metal foil is F, and the metal layer (M_SThe metal layer having) was represented as M.
I) PI / M
II) F / PI / M
III) M / PI / M
[0029]
Here, the polyimide layer may be a single-layer polyimide layer (PI-a) or a multilayer structure of a polyimide layer (PI-a) and a polyimide layer (PI-c)._S) Is a polyimide layer (PI-a). In the above aspect III), both sides of the polyimide layer are metal layers (M_SThe polyimide layer (PI-a) is applied to at least one, preferably two, of the layers in contact. Moreover, the polyimide layer (PI-a) and the polyimide layer (PI-c) do not have to be a single layer, and may be a multilayer. For example, if the polyimide layer (PI-a) is represented by a and the polyimide layer (PI-c) is represented by c, polyimide layers such as a / c, a / c / a, and c / c / a are exemplified. The Similarly, the metal layer M is the first metal layer (M) in contact with the polyimide layer (PI-a)._S), M_SIf the metal layer formed thereon is M2, and further the metal layer formed thereon is M3, M4, then M_S, M_S/ M2, M_SThere are layer structures such as / M2 / M3. Here, the metal layers after M2 are collectively referred to as a second metal layer. Therefore, the metal layer of the second layer may be composed of a plurality of layers, and they may be formed by a sputtering method or a plating method. Preferably, a majority of the thickness of the metal layer of the second layer, more preferably 80% or more is copper or a copper alloy formed by electrolytic plating.
[0030]
Although the metal layer (M) may be a single layer, it has a two-layer structure, and the first metal layer (Ms) in contact with the polyimide layer is composed of at least one metal selected from nickel, chromium, and cobalt. Furthermore, it is preferable that the second layer provided thereon is made of copper. Here, the term “metal” is interpreted to include an alloy containing the metal as a main component.
[0031]
When forming a two-layer structure, first, one kind of metal or an alloy of two or more kinds of metals is laminated on a polyimide resin layer by a sputtering method to form a metal layer (Ms). What laminated | stacked the layer is preferable. As the metal for forming the metal layer (Ms), at least one metal selected from nickel, chromium, and cobalt or an alloy containing these as a main component is preferable.
[0032]
In the metal layer formed by sputtering, the thickness of the first metal layer (Ms) in contact with the polyimide is preferably 0.5 to 10 nm, more preferably 2.0 to 5.0 nm. If the thickness is less than 0.5 nm, the adhesive strength between the metal layer and the polyimide layer is lowered, the adhesive strength after being exposed to a high-temperature and high-humidity environment is rapidly deteriorated, and the reliability cannot be maintained. On the other hand, if it is thicker than 10 nm, there is a high possibility that the fine pattern workability of the wiring will be poor.
[0033]
The second metal layer is preferably a copper layer, and this second layer is formed by sputtering or electrolytic plating, and may comprise a plurality of layers. Advantageously, a copper layer that can withstand the current density of the electrolytic plating method is formed by sputtering, and a copper foil thin film having a predetermined thickness is formed later by electrolytic plating.
When the second layer is formed by a sputtering method and an electrolytic plating method, the thickness of the metal second layer by the sputtering method is preferably 10 nm or more, more preferably 100 nm or more. If it is too thick, the cost will be too high, and if it is too thin, it will become high resistance during subsequent electrolytic plating film formation, and defects such as burnout will easily occur. Further, a copper layer is laminated on the metal layer formed by the sputtering method by an electrolytic plating method. The thickness of the metal layer in the electrolytic plating method can be set to an arbitrary thickness.
[0034]
In the present invention, as the sputtering method, DC (direct current) bipolar sputtering, DC tripolar sputtering, RF (radio frequency) sputtering, DC magnetron sputtering, RF magnetron sputtering, ion beam sputtering, or the like can be used. The DC magnetron sputtering method is preferable, which is advantageous in terms of simplicity of the apparatus, high utilization efficiency of the target material to be sputtered, film formation stability, and the like.
[0035]
In sputtering, gas species such as helium, neon, argon, krypton, xenon, and nitrogen can be used. However, argon gas is generally used because it is easily available and does not react with metal during film formation. Yes.
[0036]
You may heat in a drying furnace in order to control the moisture content etc. of the polyimide formed into a film as a pre-process of sputtering. In order to dry efficiently, it is good to heat at the temperature of room temperature-200 degreeC in a vacuum.
[0037]
As the electrolytic plating method, a copper sulfate bath, a copper pyrophosphate bath, a copper cyanide bath, or the like can be used. The electrolytic plating method using a copper sulfate bath is preferred, and there are few decomposition products of the plating bath composition, which is advantageous from the standpoint of easy liquid management and simple wastewater treatment.
It is also possible to add an additive for the purpose of refining crystal grains of the plating film, making it glossy, leveling, and uniformity of film thickness. The additive is adsorbed on the cathode surface, obstructs the reaction on the cathode surface, and multinucleation of the crystal is performed, and it can be expected that the crystal is refined, glossed, improved in leveling, improved in physical properties, and improved in throwing power.
[0038]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
First, a synthesis example of polyimide is shown.
[0039]
Synthesis example 1
Put DMAc in a thermocouple, stirrer, and reaction vessel into which nitrogen can be introduced. Pyromellitic anhydride (PMDA) is charged into the reaction vessel while the reaction vessel is immersed in ice water, and then 2,2'-bis [4- (4-aminophenoxy) phenyl] propane ( BAPP). The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature to obtain a polyamic acid solution a having a solution viscosity of 3,000 cps.
[0040]
Synthesis example 2
The reaction vessel containing DMAc was immersed in ice water, and pyromellitic anhydride (PMDA) was added thereto, followed by 1,3-bis (4-aminophenoxy) benzene (TPE-R). The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature to obtain a polyamic acid solution b having a solution viscosity of 3,200 cps.
[0041]
Synthesis example 3
The reaction vessel containing DMAc was immersed in ice water, and pyromellitic anhydride (PMDA) was added thereto, and then 4,4′-bis (4-aminophenoxy) biphenyl (BAPB) was added. The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature to obtain a polyamic acid solution c having a solution viscosity of 3,500 cps.
[0042]
Synthesis example 4
The reaction vessel containing DMAc was immersed in ice water, and pyromellitic anhydride (PMDA) was added thereto, followed by 4,4′-diaminophenyl ether (DAPE). The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature to obtain a polyamic acid solution d having a solution viscosity of 2,850 cps.
[0043]
Synthesis example 5
The reaction vessel containing DMAc was immersed in ice water, and pyromellitic anhydride (PMDA) was added thereto, followed by 4,4′-diamino-2,2′-dimethylbiphenyl (DADMB). The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature to obtain a polyamic acid solution e having a solution viscosity of 3,750 cps.
[0044]
Synthesis example 6
A reaction vessel containing DMAc was immersed in ice water, pyromellitic anhydride (PMDA) was added thereto, and then paraphenylenediamine (PDA) was introduced. The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature to obtain a polyamic acid solution f having a solution viscosity of 4000 cps.
[0045]
Example 1
As the copper foil, a copper foil manufactured by Mitsui Mining & Smelting Co., Ltd. (NA-VLP, 18 μm thick. Hereinafter, the copper foil is simply referred to as copper foil) was used. After applying the polyamic acid solution a prepared in Synthesis Example 1 on this copper foil, the solvent was removed by heating and drying at 130 ° C. Thereafter, heat treatment was carried out from room temperature to 280 ° C. for about 4 hours to imidize to obtain a single-sided copper-clad laminate in which a polyimide layer having a total thickness of about 40 μm was formed on a copper foil.
[0046]
This laminate was set in a DC magnetron sputtering apparatus, and a metal thin film was formed on the polyimide surface. The inside of the tank where the sample is set is 1 x 10^-3After reducing the pressure to Pa, argon gas was introduced and the degree of vacuum was 1 × 10.^-1Plasma was generated with a DC power source at Pa. Nickel (99.99 wt%) was deposited on 3 nm polyimide by this plasma.
After the nickel film formation, copper (99.99 wt%) was formed on the nickel film in a thickness of 200 nm under the same atmosphere.
Further, an 18 μm thick copper plating layer was formed in an electrolytic plating bath using the copper sputtered film as an electrode. A copper sulfate bath (copper sulfate 100 g / L, sulfuric acid 220 g / L, chlorine 40 mg / L, anode is phosphorous copper) is used for the electrolytic plating bath, and the current density is 2.5 A / dm.²The plating film was formed by. After plating, it was washed with sufficient distilled water and dried.
[0047]
Thus, copper foil / polyimide layer / nickel layer (M_S) / Copper sputter layer / electrolytically plated copper layer to obtain a double-sided copper-clad laminate. Polyimide layer and nickel layer (M_S) And the metal layer (M) having an electrolytically plated copper layer, the copper foil side of this double-sided copper-clad laminate is etched entirely with ferric chloride to form a single-sided copper-clad laminate, The electrolytic plated copper layer was etched using a photoresist and ferric chloride to obtain a circuit pattern of 100 μmW.
[0048]
Measure the peel strength of the flexible printed circuit board obtained after normal exposure, peel strength after exposure to 168 hr in an atmosphere of 150 ° C, and peel strength after exposure to 96 hr in an environment of 121 ° C and 100% RH using the 90 ° peel method. did. In addition, the same measurement as described above was carried out on a plating pattern of 0.5 μm that was treated with an electroless Sn plating solution of Tinposit LT-34 (manufactured by Shipley First Co., Ltd.) at 70 ° C. for 3 min.
[0049]
  Bond strength between polyimide and metal is 1100 under normal conditionsN / m1050 after processing at 150 ° C. for 168 hoursN / m, 950 after treatment at 121 ° C, 100%, 96 hrN / mAnd had good adhesion and reliability. Also, the adhesive strength after Sn plating is 1000 under normal conditions.N / m950 after processing at 150 ° C. for 168 hoursN / m, 121 ° C., 100%, 96 hours after treatment, 900N / mAnd had good adhesion and reliability.
[0050]
Example 2
  A laminate was produced and evaluated in the same manner as in Example 1 except that the polyamic acid solution b prepared in Synthesis Example 2 was applied onto a copper foil.
  Bond strength between polyimide and metal is 1050 in normal stateN / mAnd after treatment at 150 ° C. for 168 hours, 900N / m, 850 after treatment at 121 ° C, 100%, 96 hrN / mAnd had good adhesion and reliability. Also, the adhesion strength after Sn plating is 1050 under normal conditions.N / m950 after processing at 150 ° C. for 168 hoursN / m, 121 ° C., 100%, 96 hours after treatment, 900N / mAnd had good adhesion and reliability.
[0051]
Example 3
  A laminate was manufactured and evaluated in the same manner as in Example 1 except that the polyamic acid solution c prepared in Synthesis Example 3 was applied onto a copper foil.
  The bond strength between polyimide and metal is 1000 in normal state.N / mAnd after treatment at 150 ° C. for 168 hours, 900N / m, 850 after treatment at 121 ° C, 100%, 96 hrN / mAnd had a reliable adhesive strength. Also, the adhesive strength after Sn plating is 1000 under normal conditions.N / mAnd after treatment at 150 ° C. for 168 hours, 900N / m, 121 ° C, 100%, 96 hours after treatment 800N / mAnd had good adhesion and reliability. The results are shown in Tables 2 and 3.
[0052]
Comparative Example 1
  A laminate was produced and evaluated in the same manner as in Example 1 except that the polyamic acid solution d prepared in Synthesis Example 4 was applied onto a copper foil.
  The bond strength between polyimide and metal is 500 under normal conditions.N / mAnd after treatment at 150 ° C. for 168 hours, 300N / m, 121 ° C, 100%, 96 hours after treatment 300N / mAnd sufficient adhesive strength was not obtained. Moreover, the adhesive strength after Sn plating is 450 under normal conditions.N / mAnd after treatment at 150 ° C. for 168 hours, 250N / m, 121 ° C., 100%, 96 hours after treatment 250N / mAnd sufficient adhesive strength was not obtained.
[0053]
Comparative Example 2
  A laminate was manufactured and evaluated in the same manner as in Example 1 except that the polyamic acid solution e prepared in Synthesis Example 5 was applied onto a copper foil.
  The bond strength between polyimide and metal is 150 under normal conditions.N / mAnd after treatment at 150 ° C. for 168 hours, 100N / m, 121 ° C., 100%, 96 hours after treatment 50N / mAnd sufficient adhesive strength was not obtained. Moreover, the adhesive strength after Sn plating is 150 under normal conditions.N / m80 after treatment at 150 ° C. for 168 hoursN / m, 121 ° C, 100%, 96 hours after treatment 60N / mAnd sufficient adhesive strength was not obtained.
[0054]
Comparative Example 3
  A laminate was manufactured and evaluated in the same manner as in Example 1 except that the polyamic acid solution f prepared in Synthesis Example 6 was applied onto a copper foil.
  The bond strength between polyimide and metal is 200 under normal conditions.N / mm150 ° C., after 168 hr treatment, 150N / m, 121 ° C., 100%, 96 hours after treatment 100N / mAnd sufficient adhesive strength was not obtained. Moreover, the adhesive strength after Sn plating is 150 under normal conditions.N / m120 ° C. after 168 hr treatment at 150 ° C.N / m, 121 ° C., 100%, 96 hours after treatment 100N / mAnd sufficient adhesive strength was not obtained.
  The results are summarized in Tables 1 and 2.
[0055]
[Table 1]

[0056]
[Table 2]

[0057]
【The invention's effect】
According to the present invention, not only the adhesive strength in the normal state but also the adhesive strength after exposure under high temperature and high humidity is high, and a polyimide laminate for a wiring board excellent in long-term reliability can be obtained. This polyimide laminate has flexibility, and can be widely used as a wiring board material for COF use for mobile phones.

Claims (4)

A polyimide precursor resin solution is applied onto a copper foil, dried, imidized to form a polyimide layer, and a metal layer (Ms) is formed on the polyimide layer by a sputtering method. A wiring board polyimide laminate, wherein the metal layer on one side is a copper foil layer, and the metal layer on the other side is a metal layer (M) having a metal layer (Ms) formed by sputtering. And a polyimide layer (PI-a) in contact with the metal layer (Ms) contains at least 50 mol% of a polyimide structural unit represented by the following general formula (1): .

(In the formula, R ₁ represents a divalent aromatic diamino compound residue having at least two ether bonds represented by the following formula (2), and R ₂ represents a tetravalent acid dianhydride residue. .)

(In the formula, X represents a divalent organic group containing one or more aromatic rings.)   The metal layer (M) is composed of two or more layers, and the first metal layer (Ms) is composed of a metal selected from nickel, chromium and cobalt or an alloy of these metals, and the first metal layer (Ms 2. The polyimide laminate for a wiring board according to claim 1, wherein at least a part of the second layer formed above is a metal layer made of copper or a copper alloy formed by electrolytic plating.   The polyimide laminate for a wiring board according to claim 1 or 2, wherein the thickness of the first metal layer (Ms) formed by sputtering is 0.5 to 10.0 nm. Applying a polyimide precursor resin solution on a copper foil, drying, imidizing to form a polyimide layer, forming a metal layer (Ms) on the polyimide layer by a sputtering method, and a metal layer ( The wiring board according to any one of claims 1 to 3, wherein the polyimide layer (PI-a) in contact with Ms) contains at least 50 mol% of a polyimide structural unit represented by the following general formula (1): For producing a polyimide laminate.

(Wherein R ₁ Represents a divalent aromatic diamino compound residue having at least two ether bonds represented by the following formula (2); ₂ Represents a tetravalent acid dianhydride residue. )

(In the formula, X represents a divalent organic group containing one or more aromatic rings.)