JP3997462B2 - Photosensitive resin composition, photosensitive dry film resist using the same, photosensitive coverlay film for flexible printed wiring board, and photosensitive coverlay film for head of hard disk device of personal computer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive dry film using a polyimide resin expected to exhibit good physical properties in place of conventional photosensitive dry films each using an acrylic resin as a binder polymer. SOLUTION: A photosensitive dry film resist which can be exposed with an ordinary exposer and can finely be patterned is provided by using a photosensitive resin composition comprising (A) a soluble polyimide, (B) a compound having a carbon-carbon double bond and (C) a photoreaction initiator as essential components, wherein the component (C) absorbs light of 400-450 nm wavelength and generates a radical.

Description

有機溶媒への溶解性の高いポリイミドを得るためには、特に２，２‘−ヘキサフルオロプロピリデンジフタル酸二無水物、２，３，３’，４‘−ビフェニルテトラカルボン酸二無水物、下記一般式：化２で表されるエステル酸二無水物、あるいは下記一般式：化３で表される酸二無水物を一部用いることが望ましい。
【００２４】
【化２】

【００２５】
【化３】

（式中、Ｒ²は、２価の有機基を表し、特に−ＣＨ₂Ｃ（ＣＨ₃）₂ＣＨ₂−，−Ｃ_qＨ_2q−及び化４から選ばれる構造が望ましい。ｑは１〜２０の整数。とくに、−Ｃ_qＨ_2q−或いはビスフェノール骨格が望ましい。）
【００２６】
【化４】

（式中、Ｒ³は、水素・ハロゲン・メトキシ・Ｃ₁〜Ｃ₁₆のアルキル基を示す。）これらのテトラカルボン酸二無水物は、単独でまたは２種以上組み合わせて用いることができる。
【００２７】
次に、このポリイミドに用いられるジアミンは、ジアミンであれば特に限定されないが、耐熱性と可溶性のバランスをとることができる点から、：化５
【００２８】
【化５】

（式中、Ｒ⁴は、−，−ＣＯ−，−Ｏ−，−Ｃ（ＣＦ₃）₂−，−Ｃ（ＣＨ₃）₂−，−ＣＯＯ−，−ＳＯ₂−を、Ｒ⁵は同一または異なって、水素、水酸基、カルボキシル基、ハロゲン、メトキシ基，Ｃ１〜Ｃ５のアルキル基を、ｆは０，１，２，３を、ｇおよびｈは、０，１，２，３，４を示す。）で表されるジアミンを用いることが好ましい。とくに、化５中のＲ⁵が水酸基もしくはカルボキシル基であるジアミンを用いると、イミドのアルカリ水溶液への溶解性を上げることができる。これらのジアミン化合物は単独でまたは２種以上組み合わせて用いることができる。
また、上記化５で表されるジアミンは、得られるポリイミドの可溶性が高くなるという点から、全ジアミン中５〜９５モル％用いることが好ましい。さらに望ましくは、全アミン中１０〜７０モル％である。
また、フィルムの柔軟性を向上することができるという点から、ジアミンの一部として下記：化６
【００２９】
【化６】

（Ｒ⁶は炭素数１〜１２の炭化水素基、フェニル基、メトキシ基を示し、ｉは１〜５の整数であり、ｊは１〜２０の整数である。）
で表されるシリコンジアミンを用いることが好ましい。
また、上記一般式（４）で表されるシリコンジアミンは、フィルムの弾性率を下げるために、全ジアミン中、５〜５０モル％用いることが好ましい。５モル％より少ないと添加する効果が不十分であり、５０モル％より多いと、フィルムが柔らかくなりすぎて弾性率が低くなりすぎたり、熱膨張係数が大きくなったりする傾向がある。
ポリアミド酸溶液を減圧下で加熱乾燥して直接イミド化する具体的な方法について説明する。
減圧下、加熱乾燥できるなら方法は問わないが、バッチ式の方法として、真空オーブン、連続式の方法として、例えば減圧装置の付随した押出し機により実施できる。押出し機は、２軸或いは３軸押出し機が好ましい。これらの方式は、生産量により選択される。ここでいう「減圧装置の付随した押出し機」とは、熱可塑樹脂の加熱および溶融押出しを行う、一般的な例えば２軸或いは３軸溶融押出し機に、減圧して溶媒を除去する装置を付随させた装置であり、従来の溶融押出し機に付設することもできるし、新たに減圧機能を組み込んだ装置を作成することもできる。この装置により、ポリアミド酸溶液が、押出し機により混練されながら、ポリアミド酸はイミド化され、溶媒とイミド化時に生成した水は除去され、最終的には生成した可溶性ポリイミドが残る。
また、前記可溶性ポリイミドに水酸基および／またはカルボキシル基を導入すると、アルカリに対する溶解性が向上する傾向があり、アルカリ溶液を現像液として用いることができるため好ましい。
【００３０】
水酸基および／またはカルボキシル基を有するポリイミドは、水酸基および／またはカルボキシル基を有するジアミンを一部含むジアミン成分と、酸２無水物成分とを重合反応させることにより、得ることができる。水酸基及び／またはカルボキシル基を有するジアミンとしては、水酸基及び／またはカルボキシル基を有していれば特に限定されることはないが以下のようなものを例示することが出来る。
【００３１】
例えば、２，５−ジアミノテレフタル酸等のジアミノフタル酸類、３，３‘−ジアミノ−４，４’−ジカルボキシビフェニル、４，４‘−ジアミノ−３，３’−ジカルボキシビフェニル、４，４‘−ジアミノ−２，２’−ジカルボキシビフェニル、４，４‘−ジアミノ−２，２’，５，５‘−テトラカルボキシビフェニル等のカルボキシビフェニル化合物類、３，３’−ジアミノ−４，４‘−ジカルボキシジフェニルメタン、２，２−ビス[３−アミノ−４−カルボキシフェニル]プロパン、２，２−ビス[４−アミノ−３−カルボキシフェニル]プロパン、２，２−ビス[３−アミノ−４−カルボキシフェニル]ヘキサフルオロプロパン、４，４’−ジアミノ−２，２‘，５，５’−テトラカルボキシジフェニルメタン等のカルボキシジフェニルメタン等のカルボキシジフェニルアルカン類、３，３‘−ジアミノ−４，４’−ジカルボキシジフェニルエーテル、４，４‘−ジアミノ−３，３’−ジカルボキシジフェニルエーテル、４，４‘−ジアミノ−２，２’−ジカルボキシジフェニルエーテル、４，４‘−ジアミノ−２，２’，５，５‘−テトラカルボキシジフェニルエーテル等のカルボキシジフェニルエーテル化合物、３，３’−ジアミノ−４，４‘−ジカルボキシジフェニルスルフォン、４，４’−ジアミノ−３，３‘−ジカルボキシジフェニルスルフォン、４，４’−ジアミノ−２，２‘−ジカルボキシジフェニルスルフォン、４，４’−ジアミノ−２，２‘，５，５’−テトラカルボキシジフェニルスルフォン等のジフェニルスルフォン化合物、２，２−ビス[４−（４−アミノ−３−カルボキシフェノキシ）フェニル]プロパン等のビス［（カルボキシフェニル）フェニル］アルカン化合物類、２，２−ビス[４−（４−アミノ−３−カルボキシフェノキシ）フェニル]スルフォン等のビス[（カルボキシフェノキシ）フェニル]スルフォン化合物をあげることができる。
【００３２】
特に、化７から選ばれるカルボキシル基を有するジアミンは、工業的に入手しやすく、好適である。
【００３３】
【化７】

（但し、式中ｑ及びｓは１〜３の整数、ｒは１〜４の整数、Ｒ⁷は、−Ｏ−，−Ｓ−，−ＣＯ−，−ＣＨ₂−，−ＳＯ₂−，−Ｃ（ＣＨ₃）₂−，−Ｃ（ＣＦ₃）₂−，−Ｏ−ＣＨ₂−Ｃ（ＣＨ₃）₂−ＣＨ₂−Ｏ−から選ばれる２価の有機基を表す。）
また、別途水酸基やカルボキシル基を１個有するジアミンを用いることもできる。例えば、 例えば、２，４−ジアミノフェノール等のジアミノフェノール類、３，３‘−ジアミノ−４，４’−ジヒドロキシビフェニル、４，４‘−ジアミノ−３，３’−ジヒドロキシビフェニル、４，４‘−ジアミノ−２，２’−ジヒドロキシビフェニル、４，４‘−ジアミノ−２，２’，５，５‘−テトラヒドロキシビフェニル等のヒドロキシビフェニル化合物類、３，３’−ジアミノ−４，４‘−ジヒドロキシジフェニルメタン、４，４’−ジアミノ−３，３‘−ジハイドロキシジフェニルメタン、４，４’−ジアミノ−２，２‘−ジハイドロキシジフェニルメタン、２，２−ビス[３−アミノ−４−ヒドロキシフェニル]プロパン、２，２−ビス[４−アミノ−３−ヒドロキシフェニル]プロパン、２，２−ビス[３−アミノ−４−ヒドロキシフェニル]ヘキサフルオロプロパン、４，４’−ジアミノ−２，２‘，５，５’−テトラヒドロキシジフェニルメタン等のヒドロキシジフェニルメタン等のヒドロキシジフェニルアルカン類、３，３‘−ジアミノ−４，４’−ジヒドロキシジフェニルエーテル、４，４‘−ジアミノ−３，３’−ジヒドロキシジフェニルエーテル、４，４‘−ジアミノ−２，２’−ジヒドロキシジフェニルエーテル、４，４‘−ジアミノ−２，２’，５，５‘−テトラヒドロキシジフェニルエーテル等のヒドロキシジフェニルエーテル化合物、３，３’−ジアミノ−４，４‘−ジヒドロキシジフェニルスルフォン、４，４’−ジアミノ−３，３‘−ジヒドロキシジフェニルスルフォン、４，４’−ジアミノ−２，２‘−ジヒドロキシジフェニルスルフォン、４，４’−ジアミノ−２，２‘，５，５’−テトラヒドロキシジフェニルスルフォン等のジフェニルスルフォン化合物、２，２−ビス[４−（４−アミノ−３−ヒドロキシフェノキシ）フェニル]プロパン等のビス［（ヒドロキシフェニル）フェニル］アルカン化合物類、４，４‘−ビス（４−アミノ−３−ヒドキシフェノキシ）ビフェニル等のビス（ヒドキシフェノキシ）ビフェニル化合物類、２，２−ビス[４−（４−アミノ−３−ヒドロキシフェノキシ）フェニル]スルフォン等のビス[（ヒドロキシフェノキシ）フェニル]スルフォン化合物、３，５−ジアミノ安息香酸等のジアミノ安息香酸類、４，４’−ジアミノ−３，３‘−ジハイドロキシジフェニルメタン、４，４’−ジアミノ−２，２‘−ジハイドロキシジフェニルメタン、２，２−ビス[３−アミノ−４−カルボキシフェニル]プロパン、４，４‘−ビス（４−アミノ−３−ヒドキシフェノキシ）ビフェニル等のビス（ヒドキシフェノキシ）ビフェニル化合物類をあげることができる。
その他にこのポリイミド組成物に用いられるジアミンは、ジアミンであれば特に限定されないが、例えば、ｐ−フェニレンジアミン、ｍ−フェニレンジアミン、４，４‘−ジアミノジフェニルメタン、４，４’−ジアミノフェニルエタン、４，４‘−ジアミノフェニルエーテル、４，４‘−ジジアミノフェニルスルフィド、４，４‘−ジジアミノフェニルスルフォン、１，５−ジアミノナフタレン、３，３−ジメチル−４，４’−ジアミノビフェニル、５−アミノ−１−（４‘−アミノフェニル）−１，３，３−トリメチルインダン、６−アミノ−１−（４‘−アミノフェニル）−１，３，３−トリメチルインダン、４，４’−ジアミノベンズアニリド、３，５−ジアミノ−３‘−トリフルオロメチルベンズアニリド、３，５−ジアミノ−４‘−トリフルオロメチルベンズアニリド、３，４’−ジアミノジフェニルエーテル、２，７−ジアミノフルオレン、２，２−ビス（４−アミノフェニル）ヘキサフルオロプロパン、４，４‘−メチレン−ビス（２−クロロアニリン）、２，２’，５，５‘−テトラクロロ−４，４’−ジアミノビフェニル、２，２‘−ジクロロ−４，４’−ジアミノ−５，５‘−ジメトキシビフェニル、３，３‘−ジメトキシ−４，４’−ジアミノビフェニル、４，４‘−ジアミノ−２，２’−ビス（トリフルオロメチル）ビフェニル、２，２−ビス［４−（４−アミノフェノキシ）フェニル］プロパン、２，２−ビス［４−（４−アミノフェノキシ）フェニル］ヘキサフルオロプロパン、１，４−ビス（４−アミノフェノキシ）ベンゼン、４，４‘−ビス（４−アミノフェノキシ）−ビフェニル、１，３‘−ビス（４−アミノフェノキシ）ベンゼン、９，９−ビス（４−アミノフェニル）フルオレン、４，４’−（ｐ−フェニレンイソプロピリデン）ビスアニリン、４，４‘−（ｍ−フェニレンイソプロピリデン）ビスアニリン、２，２’−ビス［４−（４−アミノ−２−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、４，４’−ビス［４−（４−アミノ−２−トリフルオロメチル）フェノキシ］−オクタフルオロビフェニル等の芳香族ジアミン；ジアミノテトラフェニルチオフェン等の芳香環に結合された２個のアミノ基と当該アミノ基の窒素原子以外のヘテロ原子を有する芳香族ジアミン；１，１−メタキシリレンジアミン、１，３−プロパンジアミン、テトラメチレンジアミン、ペンタメチレンジアミン、オクタメチレンジアミン、ノナメチレンジアミン、４，４−ジアミノヘプタメチレンジアミン、１，４−ジアミノシクロヘキサン、イソフォロンジアミン、テトラヒドロジシクロペンタジエニレンジアミン、ヘキサヒドロ−４，７−メタノインダニレンジメチレンジアミン、トリシクロ［６，２，１，０^2.7］−ウンデシレンジメチルジアミン、４，４‘−メチレンビス（シクロヘキシルアミン）等の脂肪族ジアミンおよび脂環式ジアミン等を挙げることができる。これらのジアミン化合物は単独でまたは２種以上組み合わせて用いることができる。
【００３４】
さらに反応性・硬化性を付与するためには、水酸基および／またはカルボキシル基を導入した可溶性ポリイミドに、これと反応可能なエポキシ基を有する化合物と反応させることにより、後述の各種の官能基を導入し、変性ポリイミドとすることができる。ここでいうエポキシ基を有する化合物は、さらに光重合性および／または熱重合性官能基として、エポキシ基、炭素間三重結合、炭素間二重結合から選ばれる官能基を二つ以上有することが好ましい。このような光重合性および／または熱重合性官能基を導入することにより、得られる組成物に良好な硬化性や接着性を付与することができる。
【００３５】
以下、水酸基および／またはカルボキシル基を有するポリイミドに官能基を導入する方法について説明する。具体的に、変性ポリイミドとは
【００３６】
【化８】

（ただし、式中ｍおよびｎは１以上の整数、Ｒ⁸は４価の有機基、Ｒ⁹は２価の有機基、Ｒ¹⁰は３価の有機基、Ｒ¹¹は化８
【００３７】
【化９】

（式中Ｒ¹²は、エポキシ基、炭素間三重結合、または炭素間二重結合からなる群から選ばれる少なくとも一種以上の官能基を有する１価の有機基）で表される有機基）で表されるポリイミドを示す。
前述の水酸基あるいはカルボキシル基を有する変性ポリイミドを有機溶媒に溶かし、エポキシ基を有する化合物と反応させることにより変性ポリイミドが得られる。前記エポキシ基を有する化合物は、エポキシ基を２個以上有するエポキシ樹脂、エポキシ基以外にさらに炭素間三重結合、炭素間二重結合から選ばれる官能基を二つ以上有する化合物が好ましい。
エポキシ基を２個以上有するエポキシ樹脂とは、エポキシ基を分子内に２個以上持っていれば特に限定されないが、以下のように例示することができる。
例えば、エピコート８２８（油化シェル社製）等のビスフェノール型エポキシ樹脂、１８０Ｓ６５（油化シェル社製）等のオルソクレゾールノボラック型エポキシ樹脂、１５７Ｓ７０（油化シェル社製）等のビスフェノールＡノボラック型エポキシ樹脂、１０３２Ｈ６０（油化シェル社製）等のトリスヒドロキシフェニルメタンノボラック型エポキシ樹脂、ＥＳＮ３７５等のナフタレンアラルキルノボラック型エポキシ樹脂、テトラフェニロールエタン１０３１Ｓ（油化シェル社製）、ＹＧＤ４１４Ｓ（東都化成）、トリスヒドロキシフェニルメタンＥＰＰＮ５０２Ｈ（日本化薬）、特殊ビスフェノールＶＧ３１０１Ｌ（三井化学）、特殊ナフトールＮＣ７０００（日本化薬）、ＴＥＴＲＡＤ−Ｘ、ＴＥＴＲＡＤ−Ｃ（三菱瓦斯化学社製）等のグリシジルアミン型樹脂などがあげられる。
エポキシ基と炭素間二重結合を有する化合物とは、エポキシ基と二重結合を同一分子内に持っていれば特に限定されないが、アリルグリシジルエーテル・グリシジルアクリレート・グリシジルメタクレート・グリシジルビニルエーテル等を例示することができる。
エポキシ基と炭素間三重結合を有する化合物とは、エポキシ基と三重結合を同一分子内に持っていれば特に限定されないが、プロパギルグリシジルエーテル・グリシジルプロピオレート・エチニルグリシジルエーテル等を例示することができる。
反応に用いられる溶媒は、エポキシ基と反応せず、水酸基および／あるいはカルボキシル基を有するポリイミドを溶解するものであれば特に限定されない。例えば、テトラヒドロフラン、ジオキサン等のエーテル系溶媒、メタノール、エタノール、ブタノール等のアルコール系溶媒、ブチルセロソルブ等のセロソルブ系あるいはヘキサメチルホスホルアミド、γ−ブチロラクトン等、キシレン、トルエンのような芳香族炭化水素が使用可能である。これらを単独または混合物として使用することができる。後に、溶媒の除去を行うので、水酸基あるいはカルボキシ基を有する熱可塑性ポリイミドを溶解し、なるべく沸点の低いものを選択することが、工程上有利である。
反応温度は、エポキシ基と水酸基・カルボキシル基と反応する４０℃以上１３０℃以下の温度で行うことが望ましい。特にエポキシ基と二重結合あるいは、エポキシ基と三重結合を有する化合物については、二重結合・三重結合が熱により架橋・重合しない程度の温度で反応させることが望ましい。具体的には、４０℃以上１００℃以下、さらに望ましくは、５０℃以上８０℃以下である。反応時間は、１時間程度から１５時間程度である。
このようにして、変性ポリイミドの溶液を得ることができる。銅箔との接着性や現像性を上げるために、この変性ポリイミド溶液に、適宜、エポキシ樹脂、アクリル樹脂、シアナートエステル樹脂、ビスマレイミド樹脂、ビスアリルナジイミド樹脂、フェノール樹脂等の熱硬化性樹脂や、ポリエステル、ポリアミド、ポリウレタン、ポリカーボネート等の熱可塑性樹脂を混ぜてもよい。
次に、（Ｂ）成分である炭素−炭素二重結合を有する化合物について説明をする。（Ｂ）成分を含むことにより、得られる組成物、ドライフィルムに熱圧着時の流動性を付与し、高い解像度を付与することができる。
特に（Ｂ）成分として一分子中に−（CHR¹³CH₂−O）−で示す繰り返し単位（ただし、R¹³は、水素もしくはメチル基、）を１個以上４０個以下持つような構造の化合物を選ぶことにより、硬化前のモノマーがアルカリ水溶液への溶解しやすいため、未露光部の樹脂はアルカリ水溶液によりすみやかに溶解除去され、短時間で良好な解像度を付与することができる。
この（Ｂ）成分は、：化１０
【００３８】
【化１０】

（ただし、式中R¹³は水素もしくはメチル基、もしくはエチル基、R¹⁴は２価の有機基、ｍおよびｎは２から２０までの整数）で表されるような、芳香環を二つ有するジ（メタ）アクリレート化合物であることが好ましい。ｍおよびｎが０もしくは１であると、組成物のアルカリ水溶液への溶解性に劣り、良好な現像性を持つことができなくなる傾向にあり、ｍおよびnが２１以上のものは材料の入手が困難であるのと、アルカリ水溶液への溶解性は良好であるが作製したフィルムが吸湿しやすくなる傾向があり好ましくない。
（Ｂ）炭素―炭素間二重結合を有する化合物としては、以下のようなものが例示できる。
例えば、アロニックスM-210、M-211B（東亞合成製）、NKエステルABE-300、A-BPE-4、A-BPE-10、A-BPE-20、A-BPE-30、BPE-100、BPE-200（新中村化学製）等のビスフェノールA EO変性ジ(メタ)アクリレート、アロニックスM-208（東亞合成製）等のビスフェノールF EO変性（n=２〜２０）ジ(メタ)アクリレート、デナコールアクリレートDA-250（ナガセ化成製）、ビスコート#540（大阪有機化学工業製）等のビスフェノールA PO変性（n=２〜２０）ジ(メタ)アクリレート、デナコールアクリレートDA-721（ナガセ化成製）等のフタル酸PO変性ジアクリレート、さらにアロニックスM-215（東亞合成製）等のイソシアヌル酸 EO 変性ジアクリレートやアロニックスM-315（東亞合成製）、NKエステルA-9300（新中村化学製）等のイソシアヌル酸 EO 変性トリアクリレートなどのアクリレートを含有していてもよい。
【００３９】
前記（Ｂ）成分は、（A）および（Ｃ）の合計量の１〜１５０重量％配合されることが好ましい。１重量％より少ないと圧着可能温度が高く、かつ解像度が悪くなる傾向にあり、１５０重量％より多いとＢステージ状態のフィルムにベタツキが見られ、熱圧着時に樹脂がしみ出しやすくなり、さらに硬化物が脆くなりすぎる傾向にある。好ましくは、１〜１００重量％の範囲であり、さらに望ましくは、５〜６０重量％である。
【００４０】
これらの混合比率を変化させることにより、感光性フィルムの耐熱性や圧着可能温度を調整することができる。
【００４１】
圧着可能温度とは、本発明にかかる感光性ドライフィルムレジストフィルムを、フレキシブルプリント基板等に圧着する際に必要な温度であり、フィルムの素材によって、その温度範囲が異なる。圧着可能温度は、好ましくは２０℃〜１５０℃であり、この温度範囲に圧着可能温度がない感光性フィルムは、使用上の問題が生じる恐れがある。具体的には、これより高い温度でなければ圧着できない感光性フィルムは、本来は光の照射により進むべき反応が熱により進んでしまったり、圧着温度と常温との温度差が大きくなりすぎて、冷却後、感光性ドライフィルムと被着体との熱膨張係数の差によるそりやカールが発生するおそれがある。また、これより低い温度でなければ圧着出来ない感光性フィルムでは、感光性フィルムの冷却が必要となり、各工程の温度差によって表面が結露し、結露水が感光性ドライフィルムの特性を損ねるおそれがある。
上記のフレキシブルプリント基板等に圧着された感光性ドライフィルムは、露光・現像により所望のパターンを描く。現像工程は、現像液をシャワーリングして、未露光部を溶解する工程であるため、感光性ドライフィルムの感光性樹脂組成物の粘着性が低ければ、現像工程中に剥離してしまうため好ましくない。よって粘着強度は、５Pa・ｍ以上である事が好ましく、１０Pa・ｍ以上であることがさらに好ましい。
【００４２】
さらに本発明の組成物には、露光現像により所望のパターンを描けるようにするために（Ｃ）成分の光反応開始剤について説明する。本発明の光反応開始剤は、４００〜４５０ｎｍの波長によりラジカルを発生する。化合物の一例として、下記：化１１で表されるアシルフォスフィンオキシド化合物が挙げられる。（式中、Ｒ²²，Ｒ²³及びＲ²⁴は、Ｃ₆Ｈ₅−，Ｃ₆Ｈ₄（ＣＨ₃）−，Ｃ₆Ｈ₂（ＣＨ₃）₃−，（ＣＨ₃）₃Ｃ−，Ｃ₆Ｈ₃Ｃｌ₂−を、Ｒ²⁵，Ｒ²⁶及びＲ²⁷は、Ｃ₆Ｈ₅−，メトキシ基，エトキシ基，Ｃ₆Ｈ₄（ＣＨ₃）−，Ｃ₆Ｈ₂（ＣＨ₃）₃−を表す。）
【００４３】
【化１１】

これにより発生したラジカルは、炭素−炭素二重結合を有する反応基（ビニル・アクロイル・メタクロイル・アリル等）と反応し架橋・重合を促進する。一般式（６）で表されるアシルフォスフィンオキシドが２個のラジカルを発生するのに対し、特に一般式（７）で表されるアシルフォスフィンオキシドは、α開裂により４個のラジカルを発生するためより好ましい。
【００４４】
光反応開始剤として種々のパーオキサイドを組み合わせて用いることができる。特に、３，３‘，４，４’−テトラ（ｔ−ブチルパーオキシカルボニル）ベンゾフェノンと色素（増感剤）を光反応開始剤として用いた組み合わせが特に好ましい。
【００４５】
色素（増感剤）の好ましい例としては、ミヒラケトン、ビス−４，４‘−ジエチルアミノベンゾフェノン、ベンゾフェノン、カンファーキノン、ベンジル、４，４’−ジメチルアミノベンジル、３，５−ビス（ジエチルアミノベンジリデン）−Ｎ−メチル−４−ピペリドン、３，５−ビス（ジメチルアミノベンジリデン）−Ｎ−メチル−４−ピペリドン、３，５−ビス（ジエチルアミノベンジリデン）−Ｎ−エチル−４−ピペリドン、３，３‘−カルボニルビス（７−ジエチルアミノ）クマリン、リボフラビンテトラブチレート、２−メチル−１−[４−（メチルチオ）フェニル]−２−モルフォリノプロパン−１−オン、２，４−ジメチルチオキサントン、２，４−ジエチルチオキサントン、２，４−ジイソプロピルチオキサントン、３，５−ジメチルチオキサントン、３，５−ジイソプロピルチオキサントン、１−フェニル−２−（エトキシカルボニル）オキシイミノプロパン−１−オン、ベンゾインエーテル、ベンゾインイソプロピルエーテル、ベンズアントロン、５−ニトロアセナフテン、２−ニトロフルオレン、アントロン、１，２−ベンズアントラキノン、１−フェニル−５−メルカプト−１Ｈ−テトラゾール、チオキサンテン−９−オン、１０−チオキサンテノン、３−アセチルインドール、２，６−ジ（ｐ−ジメチルアミノベンザル）−４−カルボキシシクロヘキサノン、２，６−ジ（ｐ−ジメチルアミノベンザル）−４−ヒドロキシシクロヘキサノン、２，６−ジ（ｐ−ジエチルアミノベンザル）−４−カルボキシシクロヘキサノン、２，６−ジ（ｐ−ジエチルアミノベンザル）−４−ヒドロキシシクロヘキサノン、４，６−ジメチル−７−エチルアミノクマリン、７−ジエチルアミノ−４−メチルクマリン、７−ジエチルアミノ−３−（１−メチルベンゾイミダゾリル）クマリン、３−（２−ベンゾイミダゾリル）−７−ジエチルアミノクマリン、３−（２−ベンゾチアゾリル）−７−ジエチルアミノクマリン、２−（ｐ−ジメチルアミノスチリル）ベンゾオキサゾール、２−（ｐ−ジメチルアミノスチリル）キノリン、４−（ｐ−ジメチルアミノスチリル）キノリン、２−（ｐ−ジメチルアミノスチリル）ベンゾチアゾール、２−（ｐ−ジメチルアミノスチリル）−３，３−ジメチル−３Ｈ−インドール等が挙げられるが、これらに限定されない。これらの中で特に好ましい色素（増感剤）は、ビス−４，４‘−ジエチルアミノベンゾフェノン等のビスー４，４’−ジアルキルアミノベンゾフェノン誘導体、あるいは３，３‘−カルボニルビス（７−ジエチルアミノ）クマリン等のクマリン誘導体である。
光反応開始剤および増感剤の総重量は、前記（A）成分および（B）成分の合計量の０．００１〜５重量部配合すること好ましく、０．０１〜５重量部とすることが、さらに好ましい。０．００１〜５重量部の範囲を逸脱すると、増感効果が得られなかったり、現像性に好ましくない影響を及ぼしたりする場合がある。なお、光反応開始剤および増感剤として、1種類の化合物を用いても良いし、数種類を混合して用いてもよい。
また、本感光性ドライフィルムレジストの銅箔への接着強度を向上させるため、上記（Ａ）、（Ｂ）、（Ｃ）成分に加えてエポキシ樹脂を（Ａ）〜（Ｃ）成分の合計重量の１〜３０重量％添加してもよい。添加するエポキシ樹脂が１重量％より少ないと、本感光性ドライフィルムレジストの銅箔への接着強度を向上が期待できず、３０重量％より多いと、硬化後のフィルムが硬く脆くなる傾向があるので好ましくない。
ここで用いるエポキシ樹脂としては、エポキシ基を分子内に２個以上持っていれば特に限定されないが、前記（Ａ）成分：可溶性ポリイミドの変性に用いたエポキシ樹脂として例示したようなエピコート８２８（油化シェル社製）等のビスフェノール樹脂、１８０Ｓ６５（油化シェル社製）等のオルソクレゾールノボラック樹脂、１５７Ｓ７０（油化シェル社製）等のビスフェノールＡノボラック樹脂、１０３２Ｈ６０（油化シェル社製）等のトリスヒドロキシフェニルメタンノボラック樹脂、ＥＳＮ３７５等のナフタレンアラルキルノボラック樹脂、テトラフェニロールエタン１０３１Ｓ（油化シェル社製）、ＹＧＤ４１４Ｓ（東都化成）、トリスヒドロキシフェニルメタンＥＰＰＮ５０２Ｈ（日本化薬）、特殊ビスフェノールＶＧ３１０１Ｌ（三井化学）、特殊ナフトールＮＣ７０００（日本化薬）、ＴＥＴＲＡＤ−Ｘ、ＴＥＴＲＡＤ−Ｃ（三菱瓦斯化学）等のグリシジルアミン型樹脂などを挙げることができる。
また、同時にエポキシ硬化剤をエポキシ樹脂に対して１〜１０重量％添加すると、効率よく硬化が進むため好ましい。エポキシ硬化剤としては、4,4'-ジアミノジフェニルメタン等のアミン化合物、イミダゾール、酸二無水物、フェノール樹脂等が一般的に用いられる。
【００４６】
感光性ドライフィルムレジストを製造するに際しては、まず、（Ａ）成分：可溶性ポリイミドと（Ｂ）成分：炭素−炭素二重結合を有する化合物、（Ｃ）成分：光反応開始剤、その他添加剤を含む感光性樹脂組成物を有機溶剤に均一に溶解する。ここで用いる有機溶剤は、感光性樹脂組成物を溶解する溶剤であればよく、例えば、ジオキソラン、ジオキサン、テトラヒドロフランなどのエーテル系溶剤、アセトン、メチルエチルケトンなどのケトン系溶剤、メチルアルコール、エチルアルコールなどのアルコール系溶剤などが用いられる。これらの溶剤は単独で用いてもよいし、２種類以上を混合して用いてもよい。後に、溶媒の除去を行うので、（A）、（B）、（C）成分を溶解し、なるべく沸点の低いものを選択することが、工程上有利である。
ついで、溶液状となった感光性樹脂組成物をPETフィルムなどのベースフィルム上に均一に塗布した後、加熱および／もしくは熱風吹き付けにより溶剤を除去し、感光性ドライフィルムレジストとする。
ベースフィルムとしては、ポリエチレンテレフタレート（以下ＰＥＴと省略する）フィルム、ポリフェニレンサルファイド、ポリイミドフィルムなど通常市販されている各種のフィルムが使用可能であるが、特にある程度の耐熱性があり安価であることからPETフィルムが好ましく使用される。また、ベースフィルムの感光性樹脂組成物を塗布する面については、後で剥離しやすいように表面処理されているものが好ましい。
本発明の感光性ドライフィルムレジストは、厚みが１０〜５０μｍであり、さらに好ましくは２０〜４０μｍである。感光性ドライフィルムレジストの厚みが小さすぎると、フレキシブルプリント配線板上の銅の回路とベースのポリイミドフィルムとの凸凹を埋め込むことができず、また、貼り合わせた後の表面の平坦性を保つことができないという点から、好ましくない。また、厚みが大きすぎると、微細なパターンを現像しにくく、またサンプルの反りが発生しやすいという点から好ましくない。
【００４７】
通常、感光性ドライフィルムレジストは、上記感光性組成物を半硬化状態（Ｂステージ）で保ったものであり、熱プレスもしくはラミネート加工時には流動性を持ち、フレキシブルプリント配線版の回路の凸凹に追従して密着し、露光時の光架橋反応、プレス加工時の熱およびプレス後に施す加熱キュアにより硬化が完了するように設計される。
【００４８】
さらに、感光性樹脂組成物をベースフィルムに塗布し乾燥して作製した感光性ドライフィルムレジストの上には、ポリエチレンフィルムなどの保護フィルムを積層することが好ましい。空気中のゴミやチリが付着することを防ぎ、感光性ドライフィルムレジストの乾燥による品質の劣化を防ぐことができる。
【００４９】
ベースフィルムの上に作製した感光性ドライフィルムレジストの上に保護フィルムを室温でラミネートすることにより、密着させる。
【００５０】
本発明にかかる三層構造シートを用いてフレキシブルプリント配線板用カバーレイを製造するに際しては、保護フィルムを除去後、回路を形成したフレキシブルプリント配線板および感光性ドライフィルムレジストを加熱ラミネ−トにより積層する。ニ層構造シートからなる感光性ドライフィルムレジストと回路を形成したフレキシブル配線板を加熱下ラミネートすることにより、感光性ドライフィルムレジストで密着被覆されたフレキシブルプリント配線板が製造される。積層時の温度が高すぎると感光性反応部位が架橋してフィルムが硬化してしまい感光性カバーレイとしての機能を失ってしまうため、積層時の温度は低いほうが好ましい。具体的には、６０℃から１５０℃であり、さらに好ましくは８０℃から１２０℃である。温度が低すぎると、感光性ドライフィルムレジストの流動性が悪くなるため、フレキシブルプリント配線板上の微細な回路を被覆することが難しく、また密着性が悪くなる傾向がある。
【００５１】
このようにしてフレキシブルプリント配線板／感光性ドライフィルムレジスト／ベースフィルムの順に積層された状態となる。ベースフィルムは積層が完了した時点で剥離してもよいし、露光が完了してから剥離してもよい。感光性ドライフィルムレジストの保護という点からは、フォトマスクパターンをのせて露光してからベースフィルムを剥離するほうが好ましい。
【００５２】
また、この感光性ドライフィルムレジストは、フレキシブルプリント配線板の回路上へ接着した後、紫外線などの光を照射後、加熱キュアすると、フィルムが硬化して、回路を絶縁保護するカバーレイとなる。
【００５３】
感光性ドライフィルムレジストに含まれる光反応開始剤は、通常波長が450ｎｍ以下の光を吸収するため、照射する光は波長が４００〜４５０ｎｍの光を有効に放射する光源を用いるとよい。
【００５４】
さらに、本発明の感光性ドライフィルムレジストをフレキシブルプリント配線板の感光性カバーレイとして用いる場合、フレキシブルプリント配線板の回路上へ接着した後、フォトマスクパターンをのせて、露光し、現像することにより、所望の位置に穴をあけることができる。
【００５５】
現像液としては、塩基性を有する水溶液あるいは有機溶媒を用いることができる。塩基性化合物を溶解させる溶媒としては水でもよいし有機溶媒でもよい。ポリイミドの溶解性を改善するため、メタノール、エタノール、プロパノール、イソプロピルアルコール、イソブタノール、N−メチルー2−ピロリドン、N，N−ジメチルホルムアミド、N，N一ジメチルアセトアミド等の水溶性有機済媒を、さらに含有していてもよく、二種類以上の溶媒を混合したものでもよい。塩基性化合物としては、１種類を用いてもよいし、２種類以上の化合物を用いてもよい。塩基性化合物の濃度は、通常０．１〜１０重量％とするが、フィルムへの影響などから、０．１〜５重量％とすることが好ましい。上記塩基性化合物としては、例えば、アルカリ金属、アルカリ土類金属またはアンモニウムイオンの、水酸化物または炭酸塩や、アミン化合物などが挙げられる。
環境への影響の少なさから、水溶液を用いることがこのましい。
【００５６】
本発明の感光性ドライフィルムレジストは、（Ａ）成分として可溶性ポリイミド、さらに（Ｂ）成分としてアルカリ水溶液へ溶解しやすい−（CHR¹³CH₂−O）−で示す繰り返し単位（ただし、R¹³は、水素もしくはメチル基、もしくはエチル基）を持つアクリレート化合物を選んでなる感光性樹脂組成物から作製することにより、露光部の樹脂は硬化し、未露光部の樹脂はアルカリ水溶液によりすみやかに溶解除去されるため、短時間で良好な解像度を持つことを特徴とする。
さらにポリイミドを主成分とすることにより、優れた電気絶縁性、耐熱性、機械特性を有するため、本発明の感光性ドライフィルムレジストは、フレキシブルプリント配線板用感光性カバーレイのほか、パソコンのハードディスク装置のヘッド用の感光性カバーレイにも適する。
【００５７】
【実施例】
以下に実施例を挙げて説明するが、本発明はこれらに限定されるものではない。実施例、実験例における感光性ドライフィルムレジストおよび三層構造シートの作製、感光性ドライフィルムレジストの評価は以下のように行った。
（１）感光性ドライフィルムレジストの作成可溶性ポリイミド樹脂を有機溶媒に固形分３０重量％になるように溶解させた後、アクリレート樹脂、光反応開始剤を混合し、感光性樹脂組成物のワニスを調整する。この感光性樹脂組成物のワニスをＰＥＴフィルム（厚み２５μｍ）上に、乾燥後の厚みが２５μｍになるように塗布し、４５℃で５分、続いて６５℃で５分乾燥して有機溶剤を除去するとともに、感光性ドライフィルムレジストをＢステージとした。
（２）感光性ドライフィルムレジストの評価得られた感光性ドライフィルムレジストについて以下の方法により諸特性の評価を行った。
＜現像性＞上記（１）で作成した感光性ドライフィルムレジストの感光性樹脂組成物面を電解銅箔（三井金属製３EC−VLP １オンス）の粗面に積層し、遮光しながら１００℃、２００００Pa・ｍでラミネート加工した。この積層体のＰＥＴフィルム上にマスクパターンをのせ、４００ｎｍの光を４００ｍＪ／ｃｍ²だけ露光する。このサンプルのＰＥＴフィルムを剥離した後、１００℃２分間加熱処理し、１％の水酸化カリウムの水溶液（液温４０℃）で３分間現像した。露光する前にカバーフィルムの上にのせるフォトマスクパターンは、５００μｍφ、２００μｍφ、１００μｍφの微細な穴及びライン／スペースが５００μｍ／５００μｍ２００μｍ／２００μｍ、１００μｍ／１００μｍのラインを描いたものである。現像によって形成したパターンは、次いで蒸留水により洗浄して、現像液を除去する。少なくとも５００μｍφの穴および５００μｍ／５００μｍのラインが現像できていれば、合格とした。
＜接着強度＞上記（１）で作成した感光性ドライフィルムレジストの感光性樹脂組成物面を電解銅箔（三井金属製３EC−VLP １オンス）の輝面に積層し、遮光しながら１００℃、２００００Pa・ｍでラミネート加工した。この積層体を、４００ｎｍの光を４００ｍＪ／ｃｍ²だけ露光し、１８０度で１時間加熱する。この積層体のピール接着強度を、ＪＩＳ Ｃ ６４８１の引き剥がし強度（１８０度）に準じて行った。
（実験例１）ポリイミドの原料として、(2,2'-ビス(4-ヒドロキシフェニル)プロパンジベンゾエート)-3,3',4,4'-テトラカルボン酸無水物（以下、ＥＳＤＡと示す）、ビス[4-(3-アミノフェノキシ)フェニル]スルフォン（以下、ＢＡＰＳ−Ｍと示す）、シリコンジアミン、ジアミノ安息香酸、[ビス(4-アミノ-3-カルボキシ)フェニル]メタン（以下、ＭＢＡＡと示す）を用いた。溶媒として、N,N'-ジメチルホルムアミド（ＤＭＦ）およびジオキソランを用いた。
（ポリイミド樹脂の合成）攪拌機を設置した500
mlのセパラブルフラスコにESDA 17.3 g
(0.030 mol)、DMF 30 gを入れて、攪拌機で攪拌して溶解させる。次に、和歌山精化製のジアミンMBAA 5.15 g
(0.018 mol)をDMF 9 gに溶解して加え、１時間激しく攪拌する。さらに、シリコンジアミンKF-8010（信越シリコーン製）7.47 g (0.009 mol)を加え、１時間程度攪拌する。最後に、BAPS-M 1.29 g (0.003 mol)を加えて、１時間激しく攪拌する。このようにして得たポリアミド溶液をテフロン（Ｒ）コートしたバットにとり、真空オーブンで、２００℃、５０００Ｐａの圧力で２時間減圧乾燥し、26.40 gの可溶性ポリイミドを得た。
【００５８】
こうして合成したポリイミド15ｇをジオキソラン50ｇに溶解させ、Sc（固形分濃度）＝ 30％のワニスを作製した。
（感光性ドライフィルムレジストの作製）以下に示す（ａ）〜（ｄ）成分を混合して感光性樹脂組成物を調整し、（１）の方法でＰＥＴフィルム上にＢステージの感光性ドライフィルムレジストを作製した。このＰＥＴフィルム付き感光性ドライフィルムレジストの上に保護フィルムをラミネートして三層構造シートを作成した。
（ａ）上記方法により合成したポリイミド樹脂 ５０重量部
（ｂ）炭素―炭素２重結合を有する化合物 ビスフェノールA ＥＯ変性（m+ｎ≒30）ジア
クリレート（新中村化学工 業（株）製ＮＫエステルA-BPE-30） １０重量部
東亞合成株式会社 アロニックスＭ−２１５４０重量部
（ｃ）光反応開始剤 3,3',4,4'-テトラ（t-ブチルパーオキシカルボニル）ベンゾフェノン １重量部
４，４‘−ジエチルアミノベンゾフェノン １重量部
現像性試験を行ったところ、１００μｍφの微細な穴及び１００μｍ／１００μｍのラインが現像でき、合格であった。接着強度は５００Pa・mであった。
（実験例２）
（変性ポリイミドの合成）実験例１で合成したポリイミド20.8ｇ（0.020 mol）をジオキソラン80ｇに溶解し、4-メトキシフェノールを0.030ｇを添加し、６０℃のオイルバスであたためながら溶解させた。この溶液にメタクリル酸グリシジル3.75g（0.0264 mol）をジオキソラン５ｇに溶解して加え、さらに触媒としてトリエチルアミン0.01 gを添加し６０℃で６時間加熱攪拌を行った。このようにして変性ポリイミドを合成した。
（感光性ドライフィルムレジストの作製）以下に示す成分を混合して感光性樹脂組成物を調整し、（１）の方法でＰＥＴフィルム上にＢステージの感光性ドライフィルムレジストを作製した。このＰＥＴフィルム付き感光性ドライフィルムレジストの上に保護フィルムをラミネートして三層構造シートを作成した。
（ａ）上記方法により合成した変性ポリイミド樹脂 ５０重量部
（ｂ）炭素―炭素２重結合を有する化合物 ビスフェノールA ＥＯ変性（m+ｎ≒30）ジア
クリレート（新中村化学工 業（株）製ＮＫエステルA-BPE-30） １０重量部
東亞合成株式会社 アロニックスＭ−２１５１０重量部
（ｃ）光反応開始剤 3,3',4,4'-テトラ（t-ブチルパーオキシカルボニル）ベンゾフェノン１重量部
３，３‘−カルボニルビス（７−ジエチルアミノ）クマリン １重量部
現像性試験を行ったところ、１００μｍφの微細な穴及び１００μｍ／１００μｍのラインが現像でき、合格であった。接着強度は６００Pa・mであった。
（実施例１）実験例２の（Ｃ）成分を以下にした以外は、同様に行った。
（Ｃ）ビス（２，４，６−トリメチルベンゾイル）フェニルフォスヒンオキサイド １重量部
現像性試験を行ったところ、１００μｍφの微細な穴及び１００μｍ／１００μｍのラインが現像でき、合格であった。接着強度は６２０Pa・mであった。
（比較例１）実験例２の（Ｃ）成分を以下にした以外は、同様に行った。
（Ｃ）ベンゾフェノン １重量部
現像性試験を行ったところ、５００μｍφの微細な穴及び５００μｍ／５００μｍのラインは現像できず不合格であった。接着強度は１２０Pa・mであった。
（比較例２）実験例２の（Ｃ）成分を以下にした以外は、同様に行った。
（Ｃ）メチルα−オキソベンゼンアセテート １重量部
現像性試験を行ったところ、５００μｍφの微細な穴及び５００μｍ／５００μｍのラインは現像できず不合格であった。接着強度は８０Pa・mであった。
（比較例３）実験例２の（Ｃ）成分を以下にした以外は、同様に行った。
（Ｃ）ベンゾイン １重量部
現像性試験を行ったところ、５００μｍφの微細な穴及び５００μｍ／５００μｍのラインは現像できず不合格であった。接着強度は５０Pa・mであった。
（比較例４）実験例２の（Ｃ）成分を以下にした以外は、同様に行った。
（Ｃ）４，４‘−ジアジドカルコン １重量部
現像性試験を行ったところ、５００μｍφの微細な穴及び５００μｍ／５００μｍのラインは現像できず不合格であった。接着強度は６０Pa・mであった。
【００５９】
【発明の効果】
上記に示したように、本発明は、通常の露光機により、露光可能なイミド系感光性樹脂組成物を用いることにより微細なパターンを描くことが出来、フィルム状のフォトレジストおよび絶縁保護フィルム永久フォトレジストとして、フレキシブルプリント配線板やパソコンのハードディスク装置のヘッド部分に使用される感光性カバーレイフィルムにも好適に用い得る。[0001]
[Industrial application fields]
The present invention relates to a photosensitive resin composition using a polyimide resin that can be exposed by a normal exposure machine, and is a dry film using the photosensitive resin composition, particularly photosensitive for a flexible printed wiring board. It relates to a coverlay film.
[0002]
Here, the photosensitive dry film resist can be broadly divided into (1) a film-like photoresist that is finally peeled off after serving as an etching resist for forming a copper circuit. (2) There are two types of photosensitive coverlay films that play two roles: insulation protection films for circuits such as printed wiring boards and film-like photoresists.
[0003]
In particular, the latter is also suitable for a photosensitive coverlay film used for a head portion of a flexible printed wiring board or a hard disk device of a personal computer. More particularly, the present invention relates to a photosensitive polyimide film produced using a soluble polyimide, a photoreaction initiator that absorbs a wavelength of 400 nm to 450 nm and generates a radical, and an acrylic compound.
[0004]
[Prior art]
A coverlay for a flexible printed wiring board is used for the purpose of circuit protection or improvement of bending characteristics of a conductor circuit pattern of a flexible printed wiring board formed using a copper-clad laminate (CCL). As this coverlay film, there is a conventional method in which a cover film made of a polyimide film or the like with an adhesive on one side is punched at a predetermined position and laminated on a CCL on which a circuit is formed by thermal lamination or pressing. It is common. However, as the miniaturization of printed wiring boards progresses, the method of aligning the circuit on the CCL after opening holes and windows in the joints between the circuit terminals and parts in the cover film is not easy to operate. There was a limit in terms of position accuracy, and there was a problem that yield was poor.
[0005]
Also, after thermocompression bonding a cover film made of a polyimide film with an adhesive on one side on the CCL on which the circuit is formed, a method of making a hole only in the cover film at a predetermined position by a method such as laser etching or plasma etching However, although the position accuracy is very good, it takes time for drilling, and there is a disadvantage that the apparatus and the operation cost are high.
[0006]
In order to solve these problems, there is a method of using a photosensitive resin composition, particularly a photosensitive coverlay film, as the coverlay film. In this method, a photosensitive resin composition is applied on a CCL on which a circuit is formed to form a photosensitive coverlay layer, or a photosensitive coverlay film is thermocompression-bonded on the CCL on which a circuit is formed, and a photomask A pattern can be exposed and exposed, and the base film can be peeled off and alkali-developed, so that holes can be accurately formed at predetermined positions. Furthermore, it is heat-cured as necessary to obtain a coverlay film. That is, the photosensitive coverlay film serves as a film-like photoresist and an insulating protective film.
[0007]
In particular, when a dry film type photosensitive coverlay film is used, the labor and time of coating and drying can be saved compared to the method of applying a photosensitive resin, and a large number of holes can be formed at once by development. Therefore, the FPC manufacturing process can be advanced quickly.
[0008]
Recently, photosensitive cover lay films mainly composed of acrylic resins have been put on the market (JP 7-278492 A, JP 07-253667 A, JP 10-254132 A, JP 10-115919 A), and solder heat resistance. There are problems with folding resistance and electrical insulation, and improvements are desired.
[0009]
Therefore, the present inventors considered that these problems can be improved by using polyimide as a main component, and decided to develop a photosensitive coverlay. Usually, a polyimide precursor such as polyamic acid is used as the photosensitive polyimide, and after exposure and development in the state of the precursor, it is heated to 250 ° C. or higher to obtain a polyimide. However, when used with a general FPC coverlay, heating to a high temperature of 250 ° C. or higher is not preferable because the crystal structure of copper changes, the copper circuit deteriorates, and adhesives other than polyimide deteriorate. . Therefore, this system uses polyimide that has already been imidized.
[0010]
Usually, polyimide is synthesized from tetracarboxylic dianhydride and diamine. A polyimide obtained from an aromatic tetracarboxylic dianhydride and an aromatic diamine is preferable because a high molecular weight polyimide can be easily obtained. Aliphatic tetracarboxylic dianhydride has low reactivity and it is difficult to obtain a high molecular weight polyimide. Moreover, since aliphatic diamine has strong basicity and precipitates from a solution system as a salt when synthesizing polyamic acid which is a precursor of polyimide, it is difficult to obtain a high molecular weight polyimide. Therefore, it is preferable to use a polyimide obtained from an aromatic tetracarboxylic dianhydride and an aromatic diamine.
[0011]
A general-purpose exposure machine typically uses a mercury lamp, a metal halide lamp, or the like, and includes i-line (365 nm), h-line (405 nm), and g-line (436 nm). A polyimide containing an aromatic tetracarboxylic acid and an aromatic diamine absorbs i-line by absorption due to π conjugation. Therefore, the combination with the photoinitiator which can generate a radical efficiently by h line | wire and g line | wire was needed.
[0012]
Therefore, in view of the actual situation, the present inventors, in order to solve the above-mentioned conventional problems, in addition to soluble polyimide and acrylic compounds, photoreaction initiators that generate radicals by absorbing wavelengths of 400 nm to 450 nm are used as raw materials. Developed the photosensitive coverlay film used in
[0013]
[Problems to be solved by the invention]
The present invention provides a photosensitive resin composition having a soluble polyimide as an essential component and a photosensitive coverlay film as a coverlay for a flexible printed wiring board.
[0014]
[Means for Solving the Problems]
The object of the present invention is achieved by taking the following configuration.
(1) (A) soluble polyimide, (B) a compound having a carbon-carbon double bond, (C) a photoreaction initiator as an essential component, and (C) the component absorbs light having a wavelength of 400 nm to 450 nm. And a radical is generated.
(2) The photosensitive resin composition according to claim 1, wherein the photoreaction initiator (C) contains 4,4′-tetra (t-butylperoxycarbonyl) benzophenone and a dye.
(3) The photosensitive resin composition according to claim 1, wherein the photoreaction initiator (C) is an acylphosphine oxide compound.
(4) The photosensitive dry film resist which consists of the photosensitive resin composition as described in any one of Claims 1-3.
(5) The photosensitive dry film resist according to any one of claims 1 to 4, which can be developed with an alkaline aqueous solution.
(6) A photosensitive dry film resist comprising a two-layer structure sheet obtained by laminating the photosensitive dry film resist according to any one of claims 4 to 5 and a support film.
(7) A photosensitive dry film resist comprising a three-layer structure sheet, wherein the photosensitive dry film resist comprising the two-layer structure sheet according to claim 6 and a protective film are laminated.
(8) The pressure-bondable temperature in the B-stage state of the photosensitive resin composition contained in the photosensitive dry film resist is 20 ° C. to 150 ° C., according to any one of claims 4 to 7, The photosensitive dry film resist as described.
(9) The photosensitive dry according to any one of claims 4 to 8, wherein the adhesive strength of the photosensitive resin composition contained in the photosensitive dry film resist to copper at 20 ° C is 5 Pa · m or more. Film resist.
(10) A photosensitive cover lay film for flexible printed wiring boards, comprising the photosensitive dry film resist according to any one of claims 4 to 9.
(11) The photosensitive dry film resist as described in any one of Claims 4-10 used for the photosensitive coverlay film for flexible printed wiring boards.
(12) A photosensitive cover lay film for a head of a hard disk device of a personal computer, comprising the photosensitive dry film resist according to any one of claims 4 to 11.
(13) The photosensitive dry film resist according to any one of claims 4 to 12, which is used for a photosensitive coverlay film for a head of a hard disk device of a personal computer. The present invention relates to a photosensitive resin composition using a polyimide resin that can be exposed by a normal exposure machine, and draws a fine pattern on a flexible printed wiring board by using the photosensitive resin composition. Can do. Soluble polyimides include, for example, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, acetamide solvents such as N, N-dimethylacetamide and N, N-diethylacetamide, and N-methyl. Pyrrolidone solvents such as 2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, tetrahydrofuran, dioxane, dioxolane, etc. Ether solvents, alcohol solvents such as methanol, ethanol, butanol, cellosolve solvents such as butyl cellosolve or hexamethylphosphoramide The A solvent that dissolves 1 g or more at 20 ° C. to 50 ° C. in 100 g of a solvent such as tyrolactone. Desirably, 5 g or more, more desirably 10 g or more, is dissolved in 100 g of the above solvent at 20 to 50 ° C. If the solubility is too low, it may be difficult to produce a photosensitive film having a desired thickness.
[0015]
The soluble polyimide is produced, for example, by the following manufacturing method.
[0016]
In order to obtain a soluble polyimide, it is necessary to select the structure of the raw acid dianhydride / diamine. In particular, it is effective to use an acid dianhydride or diamine having a bending group such as an ether bond, carbonyl, sulfone or sulfide. Regarding the diamine, solubility is improved even if it has an amino group or a side chain at the meta position or ortho position. Even if silicon diamine having a siloxane bond is used, the solubility can be improved. Even if it does not have a bending group, those having an asymmetric structure such as 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride are also useful for improving the solubility. Each structure will be described later.
[0017]
The soluble polyimide used in the present invention can be obtained from the precursor polyamic acid, but the polyamic acid is obtained by reacting a diamine and an acid dianhydride in an organic solvent. In an inert atmosphere such as argon or nitrogen, diamine is dissolved in an organic solvent or diffused in a slurry state, and acid dianhydride is dissolved in an organic solvent and added in a slurry state or added in a solid state. To do.
In this case, if the diamine and the acid dianhydride are substantially equimolar, it becomes a polyamic acid of one kind of acid component and one kind of diamine component, but each uses two or more kinds of acid dianhydride components and diamine components, A polyamic acid copolymer can be optionally obtained by adjusting the molar ratio of the total amount of the diamine component and the total amount of the acid dianhydride component to be substantially equimolar.
[0018]
For example, diamine component-1 and diamine component-2 may be added to an organic polar solvent first, and then an acid dianhydride component may be added to form a polyamic acid polymer solution. Alternatively, the diamine component-1 may be added to the organic polar solvent in advance, the acid dianhydride component may be added, and after stirring for a while, the diamine component-2 may be added to form a polyamic acid polymer solution. Alternatively, the acid dianhydride component is added in advance to the organic polar solvent, diamine component-1 is added, diamine component-2 is added after stirring for a while, and diamine component-3 is added after stirring for a while. A solution of the polyamic acid polymer may be used.
[0019]
The reaction temperature at this time is desirably -20 ° C to 90 ° C. The reaction time is about 30 minutes to 24 hours.
Here, the average molecular weight of the polyamic acid is desirably 5,000 to 1,000,000. When the average molecular weight is less than 5,000, the molecular weight of the finished polyimide composition is low, and the resin tends to become brittle even if the polyimide composition is used as it is. On the other hand, when it exceeds 1,000,000, the viscosity of the polyamic acid varnish tends to increase, and the handling may be difficult.
[0020]
It is also possible to combine various organic additives, inorganic fillers, or various reinforcing materials with this polyimide resin. Examples of the organic polar solvent used in the polyamic acid formation reaction include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, N, Acetamide solvents such as N-dimethylacetamide and N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol , Phenol solvents such as xylenol, halogenated phenol, catechol, ether solvents such as tetrahydrofuran, dioxane, dioxolane, alcohol solvents such as methanol, ethanol, butanol, cellosolve such as butyl cellosolve or hexame Ruhosuhoruamido The Tyrolactone and the like can be mentioned, and these are preferably used alone or as a mixture, but aromatic hydrocarbons such as xylene and toluene can also be used. The solvent is not particularly limited as long as it dissolves polyamic acid. In a preferred method for producing polyimide, which will be described later, polyamic acid is synthesized, and then the polyamic acid solution is heated under reduced pressure to simultaneously remove the solvent and imidize. It is advantageous in the process to select a low one.
[0021]
Next, the process of imidizing polyamic acid will be described.
When the polyamic acid is imidized, water is generated. The generated water easily hydrolyzes the polyamic acid and causes a decrease in molecular weight. As a method of imidizing while removing this water,
1) A method of adding an azeotropic solvent such as toluene and xylene and removing it by azeotropic distillation.
2) A chemical imidization method in which an aliphatic acid dianhydride such as acetic anhydride and a tertiary amine such as triethylamine, pyridine, picoline, and isoquinoline are added.
3) Method of heating imidization under reduced pressure
There is. Any method may be used, but the method of 3) is the point that the water generated by imidization is heated under reduced pressure and actively removed from the system to suppress hydrolysis and avoid a decrease in molecular weight. Most desirable. In the method 3), the acid dianhydride used as a raw material is mixed with a tetracarboxylic acid ring-opened by hydrolysis or one of the acid dianhydride hydrolyzed, and the polyamic acid polymerization reaction is performed. Even when the polyamic acid is stopped and becomes a low molecular weight polyamic acid, the heated acid dianhydride is closed again by heating under reduced pressure at the time of imidization, and becomes acid dianhydride. It can be expected that the molecular weight of the polyimide will be larger than the molecular weight of the polyamic acid before the imidation reaction by reacting with the amine remaining in the interior.
The heating conditions for imidization are 80 to 400 ° C. It is 100 degreeC or more by which imidation is performed efficiently and water is removed efficiently, It is 120 degreeC or more desirably. The maximum temperature is preferably set to be equal to or lower than the thermal decomposition temperature of the polyimide to be used. Usually, imidization is almost completed at about 250 to 350 ° C. Therefore, the maximum temperature can be set to this level.
The pressure is preferably reduced as long as the pressure is reduced, but may be any pressure that can efficiently remove water generated during imidization under the above heating conditions. Specifically, the pressure for heating under reduced pressure is 0.09 MPa to 0.0001 MPa, desirably 0.08 MPa to 0.0001 MPa, and more desirably 0.07 MPa to 0.0001 MPa.
The acid dianhydride used in this polyimide is not particularly limited as long as it is an acid dianhydride, but it is preferable to use an acid dianhydride having 1 to 4 aromatic rings or an alicyclic acid dianhydride. From the viewpoint of sex. The following can be illustrated as specific examples.
For example, 2,2'-hexafluoropropylidenediphthalic dianhydride, 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ', 4,4'-tetracarboxylic dianhydride, butane Tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4 Cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbonane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofuran Tetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,2 2] -Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride or the like, or aliphatic cycloaliphatic tetracarboxylic dianhydride; pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2, 3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride Anhydride, 3,3 ′, 4,4′-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4 Dicarboxyphenoxy) diphenyl sulfide Dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ′ , 4,4′-perfluoroisopropylidenediphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene -Bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (triphenylphthalic acid) Acid) -4,4'-diphenylmethane dianhydride and other aromatic tetracarboxylic dianhydrides; 1,3,3a, 4,5,9b-hexahydro-2,5-dioxo- -Furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5-methyl-5- (tetrahydro-2,5-dioxo-3 -Furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3 -Furanyl) -naphtho [1,2-c] furan-1,3-dione and the like. These tetracarboxylic dianhydrides can be used alone or in combination of two or more.
[0022]
In particular, it is desirable to use an acid dianhydride having a structure of Chemical Formula 1 in order to express heat resistance and mechanical properties at a high level. (R ¹⁷ Is directly connected -O--CH ₂ − · − (C═O) − · −C (CH _Three ) ₂ − · −C (CF _Three ) ₂ -, -O-R ² -O- or-(C = O) -O-R ² -O- (C = O)-is represented. However, R ² Is a divalent organic group. )
[0023]
[Chemical 1]

In order to obtain a polyimide having high solubility in an organic solvent, in particular, 2,2′-hexafluoropropylidenediphthalic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, It is desirable to partially use an ester dianhydride represented by the following general formula: Chemical Formula 2 or an acid dianhydride represented by the following general formula: Chemical Formula 3.
[0024]
[Chemical 2]

[0025]
[Chemical 3]

(Wherein R ² Represents a divalent organic group, in particular —CH ₂ C (CH _Three ) ₂ CH ₂ -, -C _q H _2q A structure selected from-and Chemical formula 4 is desirable. q is an integer of 1-20. In particular, -C _q H _2q -Or a bisphenol skeleton is desirable. )
[0026]
[Formula 4]

(Wherein R ^Three Is hydrogen, halogen, methoxy, C ₁ ~ C ₁₆ Represents an alkyl group. ) These tetracarboxylic dianhydrides can be used alone or in combination of two or more.
[0027]
Next, the diamine used in this polyimide is not particularly limited as long as it is a diamine, but from the viewpoint that a balance between heat resistance and solubility can be achieved:
[0028]
[Chemical formula 5]

(Wherein R ^Four -, -CO-, -O-, -C (CF _Three ) ₂ -, -C (CH _Three ) ₂ -, -COO-, -SO ₂ −, R ^Five Are the same or different, hydrogen, hydroxyl group, carboxyl group, halogen, methoxy group, C1-C5 alkyl group, f is 0, 1, 2, 3 and g and h are 0, 1, 2, 3, 4 is shown. It is preferable to use a diamine represented by In particular, R in chemical formula 5 ^Five When a diamine having a hydroxyl group or a carboxyl group is used, the solubility of the imide in an alkaline aqueous solution can be increased. These diamine compounds can be used alone or in combination of two or more.
Moreover, it is preferable to use 5-95 mol% of diamine represented by the said Chemical formula 5 from the point that the solubility of the polyimide obtained becomes high. More desirably, it is 10 to 70 mol% in the total amine.
Moreover, from the point that the softness | flexibility of a film can be improved, the following:
[0029]
[Chemical 6]

(R ⁶ Represents a hydrocarbon group having 1 to 12 carbon atoms, a phenyl group, or a methoxy group, i is an integer of 1 to 5, and j is an integer of 1 to 20. )
It is preferable to use silicon diamine represented by
Moreover, it is preferable to use 5-50 mol% of silicon diamine represented by the said General formula (4) in order to reduce the elasticity modulus of a film. When the amount is less than 5 mol%, the effect of addition is insufficient, and when the amount is more than 50 mol%, the film tends to be too soft and the elastic modulus tends to be too low, or the thermal expansion coefficient tends to increase.
A specific method for directly imidizing the polyamic acid solution by heating and drying under reduced pressure will be described.
Any method can be used as long as it can be heat-dried under reduced pressure. However, it can be carried out as a batch method, a vacuum oven, a continuous method, for example, an extruder with a decompression device. The extruder is preferably a biaxial or triaxial extruder. These methods are selected depending on the production amount. The term “extruder with a decompression device” as used herein refers to an ordinary biaxial or triaxial melt extruder that performs heating and melt extrusion of a thermoplastic resin, and an apparatus that removes the solvent by decompression. It can be attached to a conventional melt extruder, or a device incorporating a new decompression function can be created. With this apparatus, the polyamic acid solution is kneaded by an extruder while the polyamic acid is imidized, the solvent and water produced during imidization are removed, and finally the produced soluble polyimide remains.
Moreover, it is preferable to introduce a hydroxyl group and / or a carboxyl group into the soluble polyimide because the alkali solubility tends to be improved and an alkaline solution can be used as a developer.
[0030]
A polyimide having a hydroxyl group and / or a carboxyl group can be obtained by polymerizing a diamine component partially containing a diamine having a hydroxyl group and / or a carboxyl group and an acid dianhydride component. The diamine having a hydroxyl group and / or a carboxyl group is not particularly limited as long as it has a hydroxyl group and / or a carboxyl group, and examples thereof include the following.
[0031]
For example, diaminophthalic acids such as 2,5-diaminoterephthalic acid, 3,3′-diamino-4,4′-dicarboxybiphenyl, 4,4′-diamino-3,3′-dicarboxybiphenyl, 4,4 Carboxyphenyl compounds such as '-diamino-2,2'-dicarboxybiphenyl, 4,4'-diamino-2,2', 5,5'-tetracarboxybiphenyl, 3,3'-diamino-4,4 '-Dicarboxydiphenylmethane, 2,2-bis [3-amino-4-carboxyphenyl] propane, 2,2-bis [4-amino-3-carboxyphenyl] propane, 2,2-bis [3-amino- 4-carboxyphenyl] hexafluoropropane, carboxy such as 4,4′-diamino-2,2 ′, 5,5′-tetracarboxydiphenylmethane Phenylalkanes, 3,3′-diamino-4,4′-dicarboxydiphenyl ether, 4,4′-diamino-3,3′-dicarboxydiphenyl ether, 4,4′-diamino-2,2′-dicarboxy Diphenyl ether, carboxydiphenyl ether compounds such as 4,4′-diamino-2,2 ′, 5,5′-tetracarboxydiphenyl ether, 3,3′-diamino-4,4′-dicarboxydiphenyl sulfone, 4,4′- Diamino-3,3′-dicarboxydiphenyl sulfone, 4,4′-diamino-2,2′-dicarboxydiphenyl sulfone, 4,4′-diamino-2,2 ′, 5,5′-tetracarboxydiphenyl sulfone Diphenylsulfone compounds such as 2,2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] pro Bis [(carboxyphenoxy) phenyl] alkane compounds such as bis [(carboxyphenoxy) phenyl] sulfone compounds such as 2,2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] sulfone be able to.
[0032]
In particular, a diamine having a carboxyl group selected from Chemical Formula 7 is industrially easily available and suitable.
[0033]
[Chemical 7]

(Wherein q and s are integers of 1 to 3, r is an integer of 1 to 4, R ⁷ Are -O-, -S-, -CO-, -CH ₂ -, -SO ₂ -, -C (CH _Three ) ₂ -, -C (CF _Three ) ₂ -, -O-CH ₂ -C (CH _Three ) ₂ -CH ₂ Represents a divalent organic group selected from —O—. )
Alternatively, a diamine having one hydroxyl group or one carboxyl group can be used. For example, diaminophenols such as 2,4-diaminophenol, 3,3′-diamino-4,4′-dihydroxybiphenyl, 4,4′-diamino-3,3′-dihydroxybiphenyl, 4,4 ′ -Hydroxybiphenyl compounds such as diamino-2,2'-dihydroxybiphenyl, 4,4'-diamino-2,2 ', 5,5'-tetrahydroxybiphenyl, 3,3'-diamino-4,4'- Dihydroxydiphenylmethane, 4,4′-diamino-3,3′-dihydroxydiphenylmethane, 4,4′-diamino-2,2′-dihydroxydiphenylmethane, 2,2-bis [3-amino-4-hydroxyphenyl] Propane, 2,2-bis [4-amino-3-hydroxyphenyl] propane, 2,2-bis [3-amino-4-hydroxyphenyl] hexafur Hydroxypropane, alkanepropane, hydroxydiphenylalkanes such as hydroxydiphenylmethane such as 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenylmethane, 3,3′-diamino-4,4′-dihydroxydiphenyl ether, 4, 4′-diamino-3,3′-dihydroxydiphenyl ether, 4,4′-diamino-2,2′-dihydroxydiphenyl ether, 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenyl ether, etc. Hydroxydiphenyl ether compound, 3,3′-diamino-4,4′-dihydroxydiphenylsulfone, 4,4′-diamino-3,3′-dihydroxydiphenylsulfone, 4,4′-diamino-2,2′-dihydroxydiphenyl Sulfone, 4,4'-diamino-2,2 ', 5,5'-tetrahydr Diphenylsulfone compounds such as xidiphenylsulfone, bis [(hydroxyphenyl) phenyl] alkane compounds such as 2,2-bis [4- (4-amino-3-hydroxyphenoxy) phenyl] propane, 4,4′-bis Bis (hydroxyphenoxy) biphenyl compounds such as (4-amino-3-hydroxyphenoxy) biphenyl, and bis [(2,2-bis [4- (4-amino-3-hydroxyphenoxy) phenyl] sulfone Hydroxyphenoxy) phenyl] sulfone compound, diaminobenzoic acids such as 3,5-diaminobenzoic acid, 4,4′-diamino-3,3′-dihydroxydiphenylmethane, 4,4′-diamino-2,2′-di Hydroxydiphenylmethane, 2,2-bis [3-amino-4-carboxyphenyl] propane, 4,4 ' Examples thereof include bis (hydroxyphenoxy) biphenyl compounds such as -bis (4-amino-3-hydroxyphenoxy) biphenyl.
In addition, the diamine used in the polyimide composition is not particularly limited as long as it is a diamine. For example, p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminophenylethane, 4,4′-diaminophenyl ether, 4,4′-didiaminophenyl sulfide, 4,4′-didiaminophenyl sulfone, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4′-diaminobiphenyl, 5-amino-1- (4′-aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4′-aminophenyl) -1,3,3-trimethylindane, 4,4 ′ -Diaminobenzanilide, 3,5-diamino-3'-trifluoromethylbenzanilide, 3,5-diamino-4'-trifluoro Methylbenzanilide, 3,4'-diaminodiphenyl ether, 2,7-diaminofluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-methylene-bis (2-chloroaniline), 2 , 2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxybiphenyl, 3,3′-dimethoxy-4 , 4′-diaminobiphenyl, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) -biphenyl 1,3′-bis (4-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) fluorene, 4,4 ′-(p-phenyleneisopropylidene) bisaniline, 4,4 ′-(m- Phenylene isopropylidene) bisaniline, 2,2′-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′-bis [4- (4-amino-2-tri) Aromatic diamines such as fluoromethyl) phenoxy] -octafluorobiphenyl; aromatic diamines having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and heteroatoms other than nitrogen atoms of the amino group; 1 , 1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, oct Methylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenediethylenediamine, tricyclo [6, 2, 1, 0 ^2.7 ] -Undecylenedimethyl diamine, aliphatic diamines such as 4,4′-methylenebis (cyclohexylamine), and alicyclic diamines. These diamine compounds can be used alone or in combination of two or more.
[0034]
Furthermore, in order to impart reactivity and curability, various functional groups described below are introduced by reacting a soluble polyimide into which hydroxyl groups and / or carboxyl groups have been introduced with a compound having an epoxy group capable of reacting therewith. And a modified polyimide. The compound having an epoxy group herein preferably has two or more functional groups selected from an epoxy group, a carbon-carbon triple bond, and a carbon-carbon double bond as photopolymerizable and / or heat-polymerizable functional groups. . By introducing such a photopolymerizable and / or thermally polymerizable functional group, good curability and adhesiveness can be imparted to the resulting composition.
[0035]
Hereinafter, a method for introducing a functional group into a polyimide having a hydroxyl group and / or a carboxyl group will be described. Specifically, with modified polyimide
[0036]
[Chemical 8]

(Where m and n are integers of 1 or more, R ⁸ Is a tetravalent organic group, R ⁹ Is a divalent organic group, R ^Ten Is a trivalent organic group, R ¹¹ Hachi 8
[0037]
[Chemical 9]

(Where R ¹² Represents a polyimide represented by an organic group) represented by a monovalent organic group having at least one functional group selected from the group consisting of an epoxy group, a carbon-carbon triple bond, or a carbon-carbon double bond. .
A modified polyimide is obtained by dissolving the above-mentioned modified polyimide having a hydroxyl group or a carboxyl group in an organic solvent and reacting with a compound having an epoxy group. The compound having an epoxy group is preferably an epoxy resin having two or more epoxy groups, or a compound having two or more functional groups selected from a carbon-carbon triple bond and a carbon-carbon double bond in addition to the epoxy group.
The epoxy resin having two or more epoxy groups is not particularly limited as long as it has two or more epoxy groups in the molecule, but can be exemplified as follows.
For example, bisphenol type epoxy resin such as Epicoat 828 (manufactured by Yuka Shell), orthocresol novolak type epoxy resin such as 180S65 (manufactured by Yuka Shell), bisphenol A novolak type epoxy such as 157S70 (manufactured by Yuka Shell) Resin, trishydroxyphenylmethane novolak type epoxy resin such as 1032H60 (manufactured by Yuka Shell), naphthalene aralkyl novolak type epoxy resin such as ESN375, tetraphenylolethane 1031S (manufactured by Yuka Shell), YGD414S (Tohto Kasei), Trishydroxyphenylmethane EPPN502H (Nippon Kayaku), special bisphenol VG3101L (Mitsui Chemicals), special naphthol NC7000 (Nippon Kayaku), TETRAD-X, TETRAD-C (manufactured by Mitsubishi Gas Chemical), etc. Glycidyl amine type resins.
The compound having an epoxy group and a carbon-carbon double bond is not particularly limited as long as it has an epoxy group and a double bond in the same molecule, but examples include allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, glycidyl vinyl ether, etc. can do.
The compound having an epoxy group and a carbon-carbon triple bond is not particularly limited as long as it has an epoxy group and a triple bond in the same molecule, but examples thereof include propargyl glycidyl ether, glycidyl propiolate, ethynyl glycidyl ether, and the like. Can do.
The solvent used in the reaction is not particularly limited as long as it does not react with the epoxy group and dissolves the polyimide having a hydroxyl group and / or a carboxyl group. For example, ether solvents such as tetrahydrofuran and dioxane, alcohol solvents such as methanol, ethanol and butanol, cellosolv systems such as butyl cellosolve, hexamethylphosphoramide, γ-butyrolactone, and aromatic hydrocarbons such as xylene and toluene. It can be used. These can be used alone or as a mixture. Since the solvent is removed later, it is advantageous in terms of the process to dissolve a thermoplastic polyimide having a hydroxyl group or a carboxy group and select one having a boiling point as low as possible.
The reaction temperature is preferably 40 ° C. or more and 130 ° C. or less at which the epoxy group reacts with the hydroxyl group / carboxyl group. In particular, for a compound having an epoxy group and a double bond or an epoxy group and a triple bond, it is desirable to react at a temperature at which the double bond / triple bond is not crosslinked or polymerized by heat. Specifically, it is 40 ° C. or higher and 100 ° C. or lower, and more preferably 50 ° C. or higher and 80 ° C. or lower. The reaction time is about 1 hour to 15 hours.
In this way, a modified polyimide solution can be obtained. In order to improve adhesiveness and developability with copper foil, this modified polyimide solution is appropriately cured with epoxy resin, acrylic resin, cyanate ester resin, bismaleimide resin, bisallyl nadiimide resin, phenol resin, etc. A resin or a thermoplastic resin such as polyester, polyamide, polyurethane, or polycarbonate may be mixed.
Next, the compound having a carbon-carbon double bond as the component (B) will be described. By including (B) component, the fluidity | liquidity at the time of thermocompression bonding can be provided to the composition obtained and a dry film, and a high resolution can be provided.
Especially as a component (B)-(CHR ¹³ CH ₂ -O)-repeating unit (provided that R ¹³ Is a compound having a structure having 1 to 40 hydrogen or methyl groups), the monomer before curing is easily dissolved in an alkaline aqueous solution. It can be dissolved and removed to give a good resolution in a short time.
This component (B) is:
[0038]
[Chemical Formula 10]

(However, R in the formula ¹³ Is hydrogen or methyl, or ethyl, R ¹⁴ Is preferably a di (meth) acrylate compound having two aromatic rings as represented by a divalent organic group, and m and n are integers from 2 to 20. When m and n are 0 or 1, the composition is poor in solubility in an alkaline aqueous solution and tends to be unable to have good developability. When it is difficult, the solubility in an alkaline aqueous solution is good, but the produced film tends to absorb moisture, which is not preferable.
(B) Examples of the compound having a carbon-carbon double bond include the following.
For example, Aronix M-210, M-211B (manufactured by Toagosei), NK ester ABE-300, A-BPE-4, A-BPE-10, A-BPE-20, A-BPE-30, BPE-100, Bisphenol A EO modified di (meth) acrylate such as BPE-200 (made by Shin-Nakamura Chemical), Bisphenol F EO modified (n = 2 to 20) di (meth) acrylate such as Aronix M-208 (made by Toagosei), Dena Bisphenol A PO-modified (n = 2 to 20) di (meth) acrylate such as coal acrylate DA-250 (manufactured by Nagase Kasei), biscoat # 540 (manufactured by Osaka Organic Chemical Industry), Denacol acrylate DA-721 (manufactured by Nagase Kasei) Phthalic acid PO-modified diacrylate such as Aronix M-215 (manufactured by Toagosei Co., Ltd.), isocyanuric acid EO-modified diacrylate such as Aronix M-315 (manufactured by Toagosei), NK ester A-9300 (manufactured by Shin-Nakamura Chemical) Contains acrylates such as isocyanuric acid EO modified triacrylate You may do it.
[0039]
The component (B) is preferably blended in an amount of 1 to 150% by weight of the total amount of (A) and (C). If the amount is less than 1% by weight, the temperature at which crimping is possible tends to be high and the resolution tends to be poor. If the amount is more than 150% by weight, the B-stage film is sticky, and the resin is likely to ooze out during thermocompression bonding and further cure. Things tend to be too brittle. Preferably, it is in the range of 1 to 100% by weight, and more desirably 5 to 60% by weight.
[0040]
By changing these mixing ratios, it is possible to adjust the heat resistance and pressure bonding temperature of the photosensitive film.
[0041]
The temperature capable of being crimped is a temperature required when the photosensitive dry film resist film according to the present invention is crimped to a flexible printed circuit board or the like, and the temperature range varies depending on the material of the film. The temperature at which pressure bonding is possible is preferably 20 ° C. to 150 ° C., and a photosensitive film having no pressure bonding temperature within this temperature range may cause a problem in use. Specifically, the photosensitive film that can only be crimped at a temperature higher than this is that the reaction that should proceed by light irradiation proceeds due to heat, or the temperature difference between the crimping temperature and room temperature becomes too large, After cooling, there is a risk of warping or curling due to the difference in thermal expansion coefficient between the photosensitive dry film and the adherend. In addition, in a photosensitive film that cannot be pressure-bonded unless the temperature is lower than this, the photosensitive film needs to be cooled, and the surface may be condensed due to a temperature difference in each step, and the condensed water may impair the characteristics of the photosensitive dry film. is there.
The photosensitive dry film pressure-bonded to the flexible printed board or the like draws a desired pattern by exposure and development. Since the developing step is a step of showering the developer and dissolving the unexposed portion, it is preferable that the photosensitive resin composition of the photosensitive dry film is peeled off during the developing step if the adhesiveness is low. Absent. Therefore, the adhesive strength is preferably 5 Pa · m or more, and more preferably 10 Pa · m or more.
[0042]
Furthermore, in the composition of the present invention, the photoreaction initiator as the component (C) will be described in order to draw a desired pattern by exposure and development. The photoreaction initiator of the present invention generates radicals with a wavelength of 400 to 450 nm. As an example of a compound: 11 The acyl phosphine oxide compound represented by these is mentioned. (Wherein R ^{twenty two} , R ^{twenty three} And R ^{twenty four} Is C ₆ H _Five -, C ₆ H _Four (CH _Three )-, C ₆ H ₂ (CH _Three ) _Three -, (CH _Three ) _Three C-, C ₆ H _Three Cl ₂ −, R ^{twenty five} , R ²⁶ And R ²⁷ Is C ₆ H _Five -, Methoxy group, ethoxy group, C ₆ H _Four (CH _Three )-, C ₆ H ₂ (CH _Three ) _Three -Represents. )
[0043]
Embedded image

The radical generated thereby reacts with a reactive group having a carbon-carbon double bond (vinyl, acroyl, methacryloyl, allyl, etc.) to promote crosslinking and polymerization. The acyl phosphine oxide represented by the general formula (6) generates two radicals, whereas the acyl phosphine oxide represented by the general formula (7) generates four radicals by α-cleavage. Therefore, it is more preferable.
[0044]
Various peroxides can be used in combination as a photoreaction initiator. In particular, a combination using 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone and a dye (sensitizer) as a photoreaction initiator is particularly preferable.
[0045]
Preferred examples of the dye (sensitizer) include mihiraketone, bis-4,4′-diethylaminobenzophenone, benzophenone, camphorquinone, benzyl, 4,4′-dimethylaminobenzyl, 3,5-bis (diethylaminobenzylidene)- N-methyl-4-piperidone, 3,5-bis (dimethylaminobenzylidene) -N-methyl-4-piperidone, 3,5-bis (diethylaminobenzylidene) -N-ethyl-4-piperidone, 3,3′- Carbonyl bis (7-diethylamino) coumarin, riboflavin tetrabutyrate, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2,4-dimethylthioxanthone, 2,4- Diethylthioxanthone, 2,4-diisopropylthioxanthone, 3,5-di Tylthioxanthone, 3,5-diisopropylthioxanthone, 1-phenyl-2- (ethoxycarbonyl) oxyiminopropan-1-one, benzoin ether, benzoin isopropyl ether, benzanthrone, 5-nitroacenaphthene, 2-nitrofluorene, anthrone 1,2-benzanthraquinone, 1-phenyl-5-mercapto-1H-tetrazole, thioxanthen-9-one, 10-thioxanthenone, 3-acetylindole, 2,6-di (p-dimethylaminobenzal)- 4-carboxycyclohexanone, 2,6-di (p-dimethylaminobenzal) -4-hydroxycyclohexanone, 2,6-di (p-diethylaminobenzal) -4-carboxycyclohexanone, 2,6-di (p- Diethylaminobe Nzal) -4-hydroxycyclohexanone, 4,6-dimethyl-7-ethylaminocoumarin, 7-diethylamino-4-methylcoumarin, 7-diethylamino-3- (1-methylbenzimidazolyl) coumarin, 3- (2-benzimidazolyl) -7-diethylaminocoumarin, 3- (2-benzothiazolyl) -7-diethylaminocoumarin, 2- (p-dimethylaminostyryl) benzoxazole, 2- (p-dimethylaminostyryl) quinoline, 4- (p-dimethylaminostyryl) ) Quinoline, 2- (p-dimethylaminostyryl) benzothiazole, 2- (p-dimethylaminostyryl) -3,3-dimethyl-3H-indole and the like, but are not limited thereto. Among these, particularly preferred dyes (sensitizers) are bis-4,4′-diethylaminobenzophenone and other bis-4,4′-dialkylaminobenzophenone derivatives, or 3,3′-carbonylbis (7-diethylamino) coumarin. And the like.
The total weight of the photoinitiator and sensitizer is preferably 0.001 to 5 parts by weight, preferably 0.01 to 5 parts by weight of the total amount of the component (A) and the component (B). More preferred. If the amount is outside the range of 0.001 to 5 parts by weight, the sensitization effect may not be obtained or the developability may be adversely affected. In addition, as a photoreaction initiator and a sensitizer, one type of compound may be used, or several types may be mixed and used.
In addition to the components (A), (B), and (C), the epoxy resin is added to the total weight of the components (A) to (C) in order to improve the adhesive strength of the photosensitive dry film resist to the copper foil. 1 to 30% by weight may be added. If less than 1% by weight of the epoxy resin is added, the adhesive strength of the photosensitive dry film resist to the copper foil cannot be expected. If more than 30% by weight, the cured film tends to be hard and brittle. Therefore, it is not preferable.
The epoxy resin used here is not particularly limited as long as it has two or more epoxy groups in the molecule, but Epicoat 828 (oil) exemplified as the above-mentioned component (A): epoxy resin used for modification of soluble polyimide. Bisphenol resin such as 180S65 (manufactured by Yuka Shell), bisphenol A novolak resin such as 157S70 (manufactured by Yuka Shell), 1032H60 (manufactured by Yuka Shell), etc. Trishydroxyphenylmethane novolak resin, naphthalene aralkyl novolak resin such as ESN375, tetraphenylolethane 1031S (manufactured by Yuka Shell), YGD414S (Tohto Kasei), trishydroxyphenylmethane EPPN502H (Nippon Kayaku), special bisphenol VG310 L (Mitsui Chemicals), special naphthol NC7000 (Nippon Kayaku), etc. can be exemplified TETRAD-X, TETRAD-C (Mitsubishi Gas Chemical) glycidylamine type resins such.
At the same time, it is preferable to add an epoxy curing agent in an amount of 1 to 10% by weight with respect to the epoxy resin because curing proceeds efficiently. As the epoxy curing agent, amine compounds such as 4,4′-diaminodiphenylmethane, imidazole, acid dianhydride, phenol resin and the like are generally used.
[0046]
In producing a photosensitive dry film resist, first, (A) component: soluble polyimide and (B) component: compound having carbon-carbon double bond, (C) component: photoreaction initiator, and other additives. The containing photosensitive resin composition is uniformly dissolved in an organic solvent. The organic solvent used here may be any solvent that dissolves the photosensitive resin composition. For example, ether solvents such as dioxolane, dioxane, and tetrahydrofuran, ketone solvents such as acetone and methyl ethyl ketone, methyl alcohol, and ethyl alcohol. Alcohol solvents are used. These solvents may be used alone or in combination of two or more. Since the solvent is removed later, it is advantageous in terms of the process to dissolve the components (A), (B), and (C) and select one having the lowest boiling point as much as possible.
Next, the photosensitive resin composition in solution is uniformly applied on a base film such as a PET film, and then the solvent is removed by heating and / or hot air blowing to form a photosensitive dry film resist.
As the base film, various commercially available films such as polyethylene terephthalate (hereinafter abbreviated as PET) film, polyphenylene sulfide, polyimide film, etc. can be used. A film is preferably used. Moreover, about the surface which apply | coats the photosensitive resin composition of a base film, what is surface-treated so that it may peel easily later is preferable.
The photosensitive dry film resist of the present invention has a thickness of 10 to 50 μm, more preferably 20 to 40 μm. If the thickness of the photosensitive dry film resist is too small, unevenness between the copper circuit on the flexible printed circuit board and the base polyimide film cannot be embedded, and the flatness of the surface after bonding must be maintained. This is not preferable because it cannot be performed. On the other hand, if the thickness is too large, it is not preferable because it is difficult to develop a fine pattern and the sample is likely to warp.
[0047]
Usually, a photosensitive dry film resist is obtained by keeping the above photosensitive composition in a semi-cured state (B stage), and has fluidity during hot pressing or laminating, and follows the circuit irregularities of a flexible printed wiring board. It is designed to be cured by photocrosslinking reaction at the time of exposure, heat at the time of pressing, and heat curing after pressing.
[0048]
Furthermore, it is preferable to laminate | stack protective films, such as a polyethylene film, on the photosensitive dry film resist produced by apply | coating the photosensitive resin composition to a base film, and drying. It is possible to prevent dust and dust in the air from adhering and to prevent deterioration of quality due to drying of the photosensitive dry film resist.
[0049]
A protective film is laminated at room temperature on the photosensitive dry film resist produced on the base film, thereby bringing it into close contact.
[0050]
When manufacturing the coverlay for a flexible printed wiring board using the three-layer structure sheet according to the present invention, after removing the protective film, the flexible printed wiring board on which the circuit is formed and the photosensitive dry film resist are heated by lamination. Laminate. By laminating a photosensitive dry film resist composed of a two-layer structure sheet and a flexible wiring board on which a circuit is formed under heating, a flexible printed wiring board coated with the photosensitive dry film resist is manufactured. If the temperature at the time of lamination is too high, the photosensitive reaction site is cross-linked and the film is cured and the function as a photosensitive coverlay is lost. Therefore, the temperature at the time of lamination is preferably low. Specifically, the temperature is 60 ° C to 150 ° C, and more preferably 80 ° C to 120 ° C. When the temperature is too low, the flowability of the photosensitive dry film resist is deteriorated, so that it is difficult to cover a fine circuit on the flexible printed wiring board and the adhesion tends to be deteriorated.
[0051]
Thus, it will be in the state laminated | stacked in order of the flexible printed wiring board / photosensitive dry film resist / base film. The base film may be peeled off when the lamination is completed, or may be peeled off after the exposure is completed. From the viewpoint of protecting the photosensitive dry film resist, it is preferable to peel off the base film after exposure with a photomask pattern.
[0052]
The photosensitive dry film resist is bonded to the circuit of the flexible printed wiring board, then irradiated with light such as ultraviolet rays, and then cured by heating to form a cover lay for insulating and protecting the circuit.
[0053]
Since the photoreaction initiator contained in the photosensitive dry film resist usually absorbs light having a wavelength of 450 nm or less, it is preferable to use a light source that effectively emits light having a wavelength of 400 to 450 nm.
[0054]
Further, when the photosensitive dry film resist of the present invention is used as a photosensitive coverlay of a flexible printed wiring board, after being adhered onto the circuit of the flexible printed wiring board, a photomask pattern is placed, exposed, and developed. A hole can be made at a desired position.
[0055]
As the developer, a basic aqueous solution or an organic solvent can be used. The solvent for dissolving the basic compound may be water or an organic solvent. In order to improve the solubility of polyimide, a water-soluble organic medium such as methanol, ethanol, propanol, isopropyl alcohol, isobutanol, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N monodimethylacetamide, Furthermore, it may contain and what mixed 2 or more types of solvent may be sufficient. As a basic compound, 1 type may be used and 2 or more types of compounds may be used. The concentration of the basic compound is usually 0.1 to 10% by weight, but is preferably 0.1 to 5% by weight because of the influence on the film. Examples of the basic compound include hydroxides or carbonates of alkali metals, alkaline earth metals, or ammonium ions, amine compounds, and the like.
It is preferable to use an aqueous solution because it has little environmental impact.
[0056]
The photosensitive dry film resist of the present invention is soluble in soluble polyimide as the component (A) and easily dissolved in an alkaline aqueous solution as the component (B)-(CHR ¹³ CH ₂ -O)-repeating unit (provided that R ¹³ Is prepared from a photosensitive resin composition comprising an acrylate compound having a hydrogen, methyl group, or ethyl group), whereby the resin in the exposed area is cured and the resin in the unexposed area is quickly dissolved in an alkaline aqueous solution. Since it is removed, it has a good resolution in a short time.
Furthermore, since it has excellent electrical insulation, heat resistance and mechanical properties due to the main component of polyimide, the photosensitive dry film resist of the present invention is not only a photosensitive coverlay for flexible printed wiring boards, but also a PC hard disk. Also suitable for photosensitive coverlays for device heads.
[0057]
【Example】
Examples are described below, but the present invention is not limited to these examples. Example , Experimental example The production of the photosensitive dry film resist and the three-layer structure sheet and the evaluation of the photosensitive dry film resist were performed as follows.
(1) Preparation of photosensitive dry film resist After dissolving a soluble polyimide resin in an organic solvent so as to have a solid content of 30% by weight, an acrylate resin and a photoinitiator are mixed, and a varnish of the photosensitive resin composition is prepared. adjust. The photosensitive resin composition varnish was applied onto a PET film (thickness 25 μm) so that the thickness after drying was 25 μm, and dried at 45 ° C. for 5 minutes and then at 65 ° C. for 5 minutes to remove the organic solvent. While removing, the photosensitive dry film resist was made into the B stage.
(2) Evaluation of photosensitive dry film resist Various characteristics of the obtained photosensitive dry film resist were evaluated by the following methods.
<Developability> The photosensitive resin composition surface of the photosensitive dry film resist prepared in (1) above was laminated on the rough surface of an electrolytic copper foil (3EC-VLP made by Mitsui Kinzoku), 100 ° C. Lamination was performed at 20000 Pa · m. A mask pattern is placed on the PET film of this laminate, and 400 nm light is applied at 400 mJ / cm. ² Just expose. After peeling off the PET film of this sample, it was heat-treated at 100 ° C. for 2 minutes and developed with a 1% aqueous solution of potassium hydroxide (liquid temperature 40 ° C.) for 3 minutes. The photomask pattern to be placed on the cover film before exposure is such that 500 μmφ, 200 μmφ, 100 μmφ fine holes and lines / spaces are drawn with 500 μm / 500 μm, 200 μm / 200 μm, and 100 μm / 100 μm lines. The pattern formed by development is then washed with distilled water to remove the developer. If at least a 500 μmφ hole and a 500 μm / 500 μm line were developed, the test was accepted.
<Adhesive strength> The photosensitive resin composition surface of the photosensitive dry film resist prepared in (1) above was laminated on the bright surface of an electrolytic copper foil (3EC-VLP made by Mitsui Kinzoku), 100 ° C while shielding light. Lamination was performed at 20000 Pa · m. This laminated body was subjected to 400 nm light at 400 mJ / cm. ² Just expose and heat at 180 degrees for 1 hour. The peel adhesive strength of this laminate was measured according to the peel strength (180 degrees) of JIS C 6481.
( Experimental example 1) As a raw material of polyimide, (2,2'-bis (4-hydroxyphenyl) propanedibenzoate) -3,3 ', 4,4'-tetracarboxylic anhydride (hereinafter referred to as ESDA), bis [ 4- (3-aminophenoxy) phenyl] sulfone (hereinafter referred to as BAPS-M), silicon diamine, diaminobenzoic acid, [bis (4-amino-3-carboxy) phenyl] methane (hereinafter referred to as MBAA) Using. N, N′-dimethylformamide (DMF) and dioxolane were used as the solvent.
(Polyimide resin synthesis) 500 equipped with a stirrer
17.3 g of ESDA in a separable flask in ml
(0.030 mol) and 30 g of DMF are added and dissolved by stirring with a stirrer. Next, 5.15 g of diamine MBAA made by Wakayama Seika
(0.018 mol) is dissolved in 9 g DMF and stirred vigorously for 1 hour. Further, 7.47 g (0.009 mol) of silicon diamine KF-8010 (manufactured by Shin-Etsu Silicone) is added and stirred for about 1 hour. Finally, 1.29 g (0.003 mol) of BAPS-M is added and stirred vigorously for 1 hour. The polyamide solution thus obtained was placed in a Teflon (R) -coated vat and dried in a vacuum oven at 200 ° C. under a pressure of 5000 Pa for 2 hours to obtain 26.40 g of soluble polyimide.
[0058]
15 g of the polyimide thus synthesized was dissolved in 50 g of dioxolane to prepare a varnish with Sc (solid content concentration) = 30%.
(Preparation of photosensitive dry film resist) The components (a) to (d) shown below are mixed to prepare a photosensitive resin composition, and a B stage photosensitive dry film is formed on the PET film by the method (1). A resist was prepared. A protective film was laminated on the photosensitive dry film resist with PET film to prepare a three-layer structure sheet.
(A) 50 parts by weight of polyimide resin synthesized by the above method
(B) Compound having carbon-carbon double bond Bisphenol A EO-modified (m + n≈30) Dia
10 parts by weight of chlorate (NK Nakamura A-BPE-30 manufactured by Shin-Nakamura Chemical Co., Ltd.)
Toagosei Co., Ltd. Aronix M-21540 parts by weight
(C) Photoinitiator 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone 1 part by weight
4,4'-diethylaminobenzophenone 1 part by weight
When a developability test was conducted, fine holes of 100 μmφ and lines of 100 μm / 100 μm could be developed, which was acceptable. The adhesive strength was 500 Pa · m.
( Experimental example 2)
(Synthesis of modified polyimide) Experimental example 20.8 g (0.020 mol) of the polyimide synthesized in 1 was dissolved in 80 g of dioxolane, 0.030 g of 4-methoxyphenol was added, and dissolved while warming in an oil bath at 60 ° C. To this solution, 3.75 g (0.0264 mol) of glycidyl methacrylate was dissolved in 5 g of dioxolane, 0.01 g of triethylamine was further added as a catalyst, and the mixture was stirred with heating at 60 ° C. for 6 hours. In this way, a modified polyimide was synthesized.
(Preparation of photosensitive dry film resist) The components shown below were mixed to prepare a photosensitive resin composition, and a B-stage photosensitive dry film resist was prepared on a PET film by the method (1). A protective film was laminated on the photosensitive dry film resist with PET film to prepare a three-layer structure sheet.
(A) Modified polyimide resin synthesized by the above method 50 parts by weight
(B) Compound having carbon-carbon double bond Bisphenol A EO-modified (m + n≈30) Dia
10 parts by weight of chlorate (NK Nakamura A-BPE-30 manufactured by Shin-Nakamura Chemical Co., Ltd.)
Toagosei Co., Ltd. Aronix M-21510 parts by weight
(C) Photoinitiator 1,3 parts by weight of 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone
3,3′-carbonylbis (7-diethylamino) coumarin 1 part by weight
When a developability test was conducted, fine holes of 100 μmφ and lines of 100 μm / 100 μm could be developed, which was acceptable. The adhesive strength was 600 Pa · m.
(Example 1 ) Experimental example It carried out similarly except having made (C) component 2 below.
(C) 1 part by weight of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide
When a developability test was conducted, fine holes of 100 μmφ and lines of 100 μm / 100 μm could be developed, which was acceptable. The adhesive strength was 620 Pa · m.
(Comparative Example 1) Experimental example It carried out similarly except having made (C) component 2 below.
(C) Benzophenone 1 part by weight
When a developability test was performed, fine holes of 500 μmφ and lines of 500 μm / 500 μm could not be developed and were rejected. The adhesive strength was 120 Pa · m.
(Comparative Example 2) Experimental example It carried out similarly except having made (C) component 2 below.
(C) 1 part by weight of methyl α-oxobenzeneacetate
When a developability test was performed, fine holes of 500 μmφ and lines of 500 μm / 500 μm could not be developed and were rejected. The adhesive strength was 80 Pa · m.
(Comparative Example 3) Experimental example It carried out similarly except having made (C) component 2 below.
(C) Benzoin 1 part by weight
When a developability test was performed, fine holes of 500 μmφ and lines of 500 μm / 500 μm could not be developed and were rejected. The adhesive strength was 50 Pa · m.
(Comparative Example 4) Experimental example It carried out similarly except having made (C) component 2 below.
(C) 4,4′-diazide chalcone 1 part by weight
When a developability test was performed, fine holes of 500 μmφ and lines of 500 μm / 500 μm could not be developed and were rejected. The adhesive strength was 60 Pa · m.
[0059]
【The invention's effect】
As described above, the present invention can draw a fine pattern by using an imide-based photosensitive resin composition that can be exposed by an ordinary exposure machine, and can be used as a film-like photoresist and an insulating protective film permanent. As a photoresist, it can also be suitably used for a photosensitive coverlay film used for a head portion of a flexible printed wiring board or a hard disk device of a personal computer.

Claims (11)

(A) Soluble polyimide, (B) Compound having carbon-carbon double bond, (C) Photoreaction initiator is contained as an essential component, and (C) component is an acylphosphine oxide compound, 400 nm to 450 nm And (A) the soluble polyimide comprises a formamide solvent, an acetamide solvent, a pyrrolidone solvent, a phenol solvent, an ether solvent, an alcohol solvent, cellosolve. A photosensitive resin composition that dissolves 1 g or more at 20 to 50 ° C. in 100 g of a solvent selected from a system solvent, hexamethylphosphoramide, and butyrolactone. A photosensitive dry film resist comprising the photosensitive resin composition according to claim 1. Photosensitive dry film resist according to claim 2, characterized in that the development with A alkali aqueous solution. The photosensitive dry film resist which consists of a 2 layer structure sheet | seat by which the photosensitive dry film resist as described in any one of Claims 2-3 and a support body film are laminated | stacked. A photosensitive dry film resist comprising a three-layer structure sheet, wherein the photosensitive dry film resist comprising a two-layer structure sheet according to claim 4 and a protective film are laminated. The photosensitive resin composition according to any one of claims 2 to 5, wherein the pressure-bondable temperature in the B-stage state of the photosensitive resin composition contained in the photosensitive dry film resist is 20 ° C to 150 ° C. Dry film resist. The photosensitive dry film resist as described in any one of the said Claims 2-6 whose adhesive strength in 20 degreeC with respect to copper of the photosensitive resin composition contained in the photosensitive dry film resist is 5 Pa * m or more. The photosensitive cover-lay film for flexible printed wiring boards which uses the photosensitive dry film resist as described in any one of Claims 2-7. The photosensitive dry film resist as described in any one of Claims 2-8 used for the photosensitive coverlay film for flexible printed wiring boards. A photosensitive cover lay film for a head of a hard disk device of a personal computer, comprising the photosensitive dry film resist according to claim 2. The photosensitive dry film resist according to any one of claims 2 to 9, which is used for a photosensitive coverlay film for a head of a hard disk device of a personal computer.