JP4274824B2 - Resin film, laminate, printed wiring board using the same, and manufacturing method thereof - Google Patents

Description

（式中Ｖは、−Ｏ−、−ＣＯ―、−Ｏ−Ｔ−Ｏ−、及び−ＣＯＯ−Ｔ−ＯＣＯ−から成る群より選択される２価の基であり、Ｔは２価の有機基。）で表される酸二無水物を用いることが、好適なガラス転移温度（あるいは軟化点という）を有するポリイミド樹脂が得られやすい点で好ましい。この中でも、特に、低吸水性や入手性に優れる点などから前記一般式（１）におけるＴが、
【００１４】
【化２】

で表される基および一般式（２）
【００１５】
【化３】

（式中、Ｚは、−Ｃ_QＨ_2Q−、−Ｃ（＝Ｏ）−、−ＳＯ₂−、−Ｏ−及び−Ｓ−から成る群より選択される二価の基であり、Ｑは１以上５以下の整数である。）で表される酸二無水物の群より選択される少なくとも一種の酸二無水物を用いることが好ましい。
【００１６】
一般式（１）で表される酸二無水物としては、例えば以下のものが例示される。４，４´―（４，４´―イソプロピリデンジフェノキシ）ビス無水フタル酸、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´−テトラカルボン酸二無水物、ｐ−フェニレンビス（トリメリット酸モノエステル無水物）、４，４´−ビフェニレンビス（トリメリット酸モノエステル無水物）、１，４−ナフタレンビス（トリメリット酸モノエステル無水物）、１，２−エチレンビス（トリメリット酸モノエステル無水物）、１，３−トリメチレンビス（トリメリット酸モノエステル無水物）、１，４−テトラメチレンビス（トリメリット酸モノエステル無水物）、１，５−ペンタメチレンビス（トリメリット酸モノエステル無水物）、１，６−ヘキサメチレンビス（トリメリット酸モノエステル無水物）などを挙げることができる。
【００１７】
前記酸二無水物の中でも、４，４´―（４，４´―イソプロピリデンジフェノキシ）ビス無水フタル酸、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´−テトラカルボン酸二無水物を用いると好適なガラス転移温度を有し、また、低吸水性や耐熱分解性等の耐熱性等の特性バランスのとれた熱可塑ポリイミド樹脂が得られるため、特に好ましい。
一般式（１）以外の酸二無水物としては、以下の酸二無水物が例示できる。ピロメリット酸、３，３´，４，４´−ベンゾフェノンテトラカルボン酸二無水物、３，３´，４，４´−ジフェニルスルホンテトラカルボン酸二無水物、１，４，５，８−ナフタレンテトラカルボン酸二無水物、２，３，６，７−ナフタレンテトラカルボン酸二無水物、４、４´−オキシジフタル酸無水物、３，３´，４，４´−ジメチルジフェニルシランテトラカルボン酸二無水物、１，２，３，４−フランテトラカルボン酸二無水物、４，４´−ビス（３，４−ジカルボキシフェノキシ）ジフェニルプロパン酸二無水物、４，４´−ヘキサフルオロイソプロピリデンジフタル酸無水物、３，３´，４，４´−ビフェニルテトラカルボン酸二無水物、２，３，３´，４´−ビフェニルテトラカルボン酸二無水物、ｐ−フェニレンジフタル酸無水物などが挙げられるが、これに限定されない。
【００１８】
これら酸二無水物は、一種のみ用いてもよく、また二種以上を任意の割合で併用してもよい。
【００１９】
前記ポリイミド樹脂は、ジアミン成分として下記一般式（３）
【００２０】
【化４】

（式中、Ｙは、−Ｃ（＝Ｏ）−、−ＳＯ₂−、−Ｏ−、−Ｓ−、−（ＣＨ₂）_m−、−ＮＨＣＯ−、−Ｃ（ＣＨ₃）₂−、−Ｃ（ＣＦ₃）₂−、−Ｃ（＝Ｏ）Ｏ−、または単結合を示す。Ｒ₂は、水素、ハロゲン基または炭素数１〜４のアルキル基、ｍ及びｒは１以上５以下の整数である。）で表される少なくとも１種類のジアミンを用いて得られるポリイミド樹脂であることが軟化点（またはガラス転移温度）を制御しやすい、耐熱性に優れる、低吸水性のポリイミド樹脂が得られやすい点で好ましい。
【００２１】
前述ポリイミド樹脂には、接着性や耐熱性、加工性等の諸特性を改善させるために、耐熱性や低吸湿性等の諸特性を損なわない範囲でエポキシ樹脂、シアン酸エステル樹脂、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、アクリル樹脂、メタクリル樹脂、ヒドロシリル硬化樹脂、アリル硬化樹脂、不飽和ポリエステル樹脂等の熱硬化性樹脂や高分子鎖の側鎖または末端にアリル基、ビニル基、アルコキシシリル基、ヒドロシリル基等の反応性基を有する側鎖反応性基型熱硬化性高分子を単独または適宜組み合わせて混合することが可能である。
【００２２】
本発明の樹脂フィルムは、算術平均粗さのカットオフ値０．００２ｍｍで測定した値Ｒａ１が、０．０５μｍ以上１μｍ以下であり、カットオフ値０．１ｍｍで測定した値Ｒａ２との比Ｒａ１／Ｒａ２が０．４以上１以下である表面形状を少なくとも片面に有する。
【００２３】
本発明の算術平均粗さＲａとは、ＪＩＳ Ｂ ０６０１（平成６年２月１日改正版）に定義されている。特に本発明の算術平均粗さＲａの数値は、光干渉式の表面構造解析装置で表面を観察により求められた数値を示す。本発明のカットオフ値とは、上記ＪＩＳ Ｂ ０６０１に記載されているが、断面曲線（実測データ）から粗さ曲線を得る際に設定する波長を示す。即ち、カットオフ値が０．００２ｍｍで測定した値Ｒａとは、実測データから０．００２ｍｍよりも長い波長を有する凹凸を除去した粗さ曲線から算出された算術平均粗さである。従って、０．００２ｍｍよりも短い波長を有する凹凸が存在しない場合は、カットオフ値が０．００２ｍｍで測定した値Ｒａは、０μｍとなる。
【００２４】
樹脂の表面に凹凸を形成する方法として、サンドブラスト加工、研磨加工等を樹脂の一部を物理的に削り取る方法が好ましく使用できる。樹脂が熱可塑性を有する場合は、エンボス加工も好ましく用いることができる。エンボス加工は樹脂のガラス転移温度（または軟化点）以上の温度で、表面に凹凸を形成した金属材料に樹脂を接触させることにより、樹脂表面に凹凸を形成することが可能となる。この際、加熱、加圧を伴なうことが好ましく、適切な凹凸が形成できる条件で加工することが好ましい。また、金属箔の粗化面を樹脂フィルムに接触させた後、樹脂の軟化点以上の温度でプレス法などで金属を加熱圧着し、後で金属箔を化学的あるいは引き剥がす等の物理的で除去する、レプリカ法と呼ばれる方法も好ましく用いることができる。
【００２５】
その他の方法として、樹脂フィルムを製造する場合に樹脂に微小な粒子を混合してフィルム化する方法などが挙げられる。
【００２６】
何れの方法であっても、サンドブラスト加工、研磨加工も適切な凹凸が形成できる条件で加工することが好ましい。
【００２７】
また、本発明の表面処理として、樹脂の表層を一部除去する樹脂の表面処理も好ましく適用できる。この表面処理方法は樹脂の表面の適度な厚みを溶解させることを目的としており、それにより金属との接着性を高めることが可能である。このことは、理由は定かでないが、この表面処理により、樹脂表面に凹凸が形成されるか、および／または、樹脂の表層を溶解により除去することにより化学構造の変化が生じ、無電解めっきとの接着性に良い影響を与えると推察している。ここで「一部除去する」とは樹脂の表層全体が均一に除去される状態、または表層が不均一に、即ち島状に除去されるまたは島状に表層が残る状態を表わす。
【００２８】
具体的に樹脂の表層を一部除去する表面処理としては、コロナ放電、大気圧プラズマ、真空プラズマ、電子線、レーザー、ＲＩＥ等の気相で処理する方法、また樹脂を溶解する液体により処理する液相処理が挙げられる。これらの処理には、樹脂表面に微小な凹凸面を形成し強固に無電解めっき皮膜を接着する効果があるとともに、樹脂表面を化学的に活性化させる効果があると考えている。これらの処理のうち、コロナ放電、大気圧プラズマ、真空プラズマ、電子線の気相で処理する方法、および液相処理する方法が工業的に簡便であり好ましく実施される。また、液相処理は樹脂を溶解させ、本発明の目的を達成するものであれば特に限定されない。具体的には広く工業的に、特にプリント配線板製造におけるデスミア工程や樹脂のエッチングに使用されている過マンガン酸塩、有機アルカリ化合物を含む水溶性液体、あるいは有機溶剤等が好ましく使用される。特に樹脂がポリイミド樹脂の場合、溶解する有機溶剤としてはアミド系溶媒すなわちＮ，Ｎ−ジメチルフォルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチル−２−ピロリドンなどであり、Ｎ，Ｎ−ジメチルフォルムアミドが特に好ましく用いられる。
【００２９】
以上、樹脂の表面処理方法について、「樹脂の表面に凹凸を形成する表面処理」、「樹脂の表層を一部除去する表面処理」に分けて、その具体的方法とともに説明したが、これらを組み合わせることも効果があることも見出した。具体的には「樹脂の表面に凹凸を形成する表面処理」と「樹脂の表層を一部除去する表面処理」を併用することであり、種々組み合わせに効果がある。この中で「樹脂の表面に凹凸を形成する表面処理」と樹脂を溶解させる液相処理を併用することに特に効果があり、その中でも金属箔を用いた表面処理を行った樹脂表面を過マンガン酸塩または有機アルカリ化合物、有機溶剤で処理することは特に効果的である。
【００３０】
いずれの方法であっても、算術平均粗さのカットオフ値０．００２ｍｍで測定した値Ｒａ１が、０．０５μｍ以上１μｍ以下であり、カットオフ値０．１ｍｍで測定した値Ｒａ２との比Ｒａ１／Ｒａ２が０．４以上１以下に制御して行うことが肝要であり、好ましくは、Ｒａ１が０．１以上０．８μｍ以下であり、Ｒａ１／Ｒａ２が０．５以上１以下であり、特に、Ｒａ１が０．２以上０．６μｍ以下であり、Ｒａ１／Ｒａ２が０．６以上１以下が好ましい。ここで、Ｒａ２は、１００μｍよりも大きい凹凸を除去した数値であるが、１００μｍ以上の波長を有する凹凸は、表面形状観察時のサンプルのセッティング時に発生するのフィルムのしわや、カールが大きな割合を占めると考えられ、フィルム本来の凹凸でない凹凸を除去するために好適であると考えて設定した数値である。一方、Ｒａ１は、２μｍ超える凹凸を除去した数値であるが、本発明者らは、これらが多くなると、例えば、Ｌ／Ｓが３０μｍ／３０μｍ以下、好ましくは１０μｍ／１０ｍμｍといった微細配線を形成する場合、配線形成性が低下する傾向があることを見出した。さらに、２μｍ以下の凹凸は、ある程度の高さがないと、すなわち、算術平均粗さ数値が０．０５μｍ以上１μｍ以下でないと接着性が低下する傾向があることも見出した。
【００３１】
すなわち、 Ｒａ１／Ｒａ２の比が０．４未満であると、２μｍを超え、１００μｍ以下の波長を有する凹凸が多いため、微細な回路を形成することが困難となる。またＲａ１／Ｒａ２が１を超えることはないが、１に近いほど２μｍ以下の波長を有する微細な凹凸を多く有する表面であるため、微細配線を形成すできる表面として好ましい。また、Ｒａ１が０．０５μｍ未満であると形成された凹凸の高さが不十分であり接着性に劣ることになり、１μｍを超えると逆に凹凸の高さが大きくなりすぎて微細な回路を形成することが困難となる。
【００３２】
表面形状を上記の範囲とするためには、用いられる樹脂フィルムに適した加工条件で表面形状を形成することが重要となる。
【００３３】
例えば、薬液により樹脂表面の一部を溶解する場合には、用いられる樹脂フィルムに合わせて、薬液の種類、濃度、及び、複数の薬液の組み合わせ等の加工用の材料や、薬液による処理温度、処理時間等の加工条件をそれぞれ選択することが必要であるが、特に樹脂フィルムの特性に合わせて、加工に用いる材料と条件の組み合わせることが重要である。
【００３４】
また樹脂フィルムが熱可塑性を有している場合は、エンボス加工やレプリカ法により微細な凹凸を形成することが好適である。レプリカ法であれば、使用する金属の種類や（表面粗度、表面形状等の加工用の材料や、プレス時の温度、圧力、時間等の加工条件をそれぞれ選択することが必要であるが、特に、熱可塑性の樹脂フィルムの特性に合わせて、加工に用いる材料と条件の組み合わせることが重要である。また、熱可塑性樹脂を用いてエンボス加工や、レプリカ法で微細な凹凸表面を形成する場合は、金属ロールや金属箔と、好適な凹凸を有する金属ロールや銅箔を使用することは当然であるが、好適な表面形状を形成するためには、熱可塑性樹脂材料に金属ロールや金属箔をプレス時の温度や圧力が特に重要である。
【００３５】
具体的には、プレス温度は、熱可塑性樹脂のガラス転移温度の−１００℃〜＋１８０℃、好ましくは−５０℃〜１５０℃の範囲。圧力は線圧が１０ｋｇｆ／ｃｍ〜２００kｇｆ／ｃｍ、好ましくは２０ｋｇｆ／ｃｍ〜１５０ｋｇｆ／ｃｍ、ライン速度は、０．５ｍ／分〜５ｍ／分、好ましくは１ｍ／分〜３ｍ／分、の範囲で行うことがこのましいが、熱可塑性樹脂材料の特性（加熱による樹脂の流動性や、ガラス転移温度、加熱時の弾性率）に合わせて好適な条件を設定することが重要である。
【００３６】
本発明の樹脂フィルムは、特定の表面を有する樹脂フィルムの機械的特性や耐熱性、加工性などの諸特性を補うなどの目的で多層樹脂フィルムとすることも可能である。多層樹脂フィルムとする場合、絶縁特性、熱的特性、機械的特性などの諸特性の特性バランスに優れる点で全層にポリイミド樹脂を含むことが好ましい。
【００３７】
接着層の積層性を付与するために、本発明の表面形状を有する面と反対側の面に、本発明の表面を有する樹脂よりも低い軟化点あるいは融点を有する樹脂層を有することも可能である。
【００３８】
本発明の樹脂フィルムの特定の表面形状を有する表面に、導体層となる金属層を形成方法としては、特に限定されないが、無電解めっき法、電気めっき法等の湿式めっき方法やスパッター法や蒸着法等の乾式めっき方法などが挙げられ、コスト的に優れる湿式めっき法が特に好ましい。あるいは、接着剤を介して金属箔を張り合わせても良い。
【００３９】
本発明の樹脂フィルムの特定の表面形状を有する表面に、電子回路を形成する方法としては、表面全体に金属層を形成し、金属層の一部分をエッチングにより除去して回路を形成する方法や、表面にめっきレジスト層を形成し露光現像したのちに、露出した本発明の表面上にめっきにより金属層を積層して、回路を形成を行う方法などが挙げられる。
【００４０】
本発明の樹脂フィルムを使用して多層回路基板を製造することも可能である。多層回路基板の製造方法では、本発明の特定の表面形状を有する面と反対側の面に、該表面を有する樹脂よりも低い軟化点あるいは融点を有する樹脂層を有することを樹脂フィルムを用いることができる。すなわち、予め回路が形成された基板に本発明の表面に特定形状を有する樹脂よりも低い軟化点あるいは融点を有する樹脂層を接触させて、プレスあるいはラミネートにより加熱および加圧して圧着した後に、特定の形状を有する表面に回路を形成することにより製造することができる。
【００４１】
次に、本発明の樹脂フィルム、積層体を用いたプリント配線板の製造法の具体例について説明する。プリント配線板の製造方法では、本発明の樹脂フィルムの特定の表面形状を有した表面に無電解めっき銅を施す。無電解めっきは、パラジュウム触媒を用いる化学めっきあるいはパラジウム、カーボン等を用いるダイレクトプレーティングを用いることができる。さらに無電解めっき銅上にレジスト膜を形成し、露光、エッチングにより回路の形成を予定する部分のレジスト被膜を取り除く。次に無電解めっき膜が露出する部分を給電電極として使用して電解銅によるパターンめっき法により回路を形成する。ついでレジスト部分を取り除き不要部分の無電解めっき層をエッチングにより取り除いて回路を形成する。この方法はセミアディティブ法と呼ばれる方法である。
【００４２】
前記方法の以外の方法として、以下のプリント配線板の製造方法も例示できる。まず上記と同様に、本発明の樹脂フィルムの特定の表面形状を有した表面に無電解めっき銅層を形成する。次に電解めっき銅を施し、電解銅めっき層表面にレジスト膜を形成し、露光工程、現像により回路の形成しない部分のレジスト膜を除去し、次にエッチングにより不要な金属層を取り除き回路を形成する。この方法は、サブストラクティブ法と呼ばれる方法である。
【００４３】
上記方法において金属層の形成方法として、無電解めっきに代えてスパッター法を用いることも可能である。また、多層のプリント配線板を製造する場合は、表面に回路が形成されたポリイミドフィルム等の樹脂フィルムを基材とするフレキシブルプリント配線板、あるいはガラスエポキシ基ビスマレイミドートリアジン基板等のリジット基板等の基板上に、熱可塑性あるいは熱硬化性の接着剤を介し、本発明の樹脂フィルムを、特定の表面形状を有する表面が外層になるように積層した後に前記のプリント配線板の製造方法と同様の方法で、本発明の樹脂フィルム上に回路を形成することも可能である。
【００４４】
前記の多層プリント配線板の製造方法において、本発明の樹脂フィルムを積層した後に、本発明の樹脂フィルム層を貫通して下層の配線板回路にいたるビアホールを形成することも可能である。ビアホールの形成は炭酸ガスレーザーやＵＶ−ＹＡＧレーザー、パンチング、ドリリング等を用いた穴開け法によって行う。小さなビアホールを形成する場合レーザーを用いた穴開け法が好ましく使用される。ビアホールを形成後、ビアホール内部および周辺に出来た樹脂の熱による炭化物を主成分とするスミヤを除去するデスミア工程を実施する。このデスミア工程は公知の方法を利用でき過マンガン酸塩を用いるウェットプロセスやプラズマ等のドライデスミアを用いることも可能である。本発明の各種積層体はプリント配線板製造において広く用いられている過マンガン酸塩系デスミアプロセスに対する耐久性を有しており好ましく使用できる。次に、前記のプリント配線板の製造方法と同様の方法で樹脂層表面およびビアホール内部に無電解めっき銅を施した後に回路を形成する事が可能である。上記のビアホールの他に、下層の配線板回路も含めた積層体全体を貫通する、スルーホールと呼ばれる貫通穴を形成してもよい。
【００４５】
本発明にかかる樹脂フィルムでは、その表面に微細な凹凸を有しているため、例えばＬ／Ｓが１０μｍ／１０μｍ程度の微細回路を形成することも可能であり、また表面の凹凸が小さいにもかかわらず、その表面上に形成された導体層との接着性に優れている。それゆえ、上記従来のフィルム状接着剤で生じる問題点を十分に解消することが可能になり、その結果、フレキシブル配線板（ＦＰＣ）やビルドアップ多層回路基板などの回路基板の製造に好適に用いることができる。なお、本発明にかかる樹脂フィルムには、その特性を低下させない限り、前述した以外の成分が含まれていてもよいことは言うまでもない。同様に、本発明にかかる樹脂フィルムにおいては、前述した以外の工程が含まれていても良いことも言うまでもない。
【００４６】
【実施例】
以下に実施例を挙げて、本発明の効果を具体的に説明するが、本発明は以下の実施例に限定されるものではなく、当業者は本発明の範囲を逸脱することなく、種々の変更、修正、及び改変を行い得る。なお、実施例中の種々の積層体の作製、接着層の合成・作製、積層、無電解めっき、各種測定・評価は以下の方法で行った。
【００４７】
［非熱可塑性ポリイミドフィルムの作製法］
３，３’，４，４’−ビフェニルテトラカルボン酸二無水物／ｐ−フェニレンビス（トリメリット酸モノエステル酸無水物）／ｐ−フェニレンジアミン／４，４’−ジアミノジフェニルエーテルをモル比で４／５／７／２の割合で合成したポリアミド酸の１７ｗｔ％のＤＭＦ（Ｎ，Ｎ−ジメチルホルムアミド）溶液９０ｇに無水酢酸１７ｇとイソキノリン２ｇからなる転化剤を混合、攪拌し、遠心分離による脱泡の後、アルミ箔上に厚さ７００μmで流延塗布した。攪拌から脱泡までは０℃に冷却しながら行った。このアルミ箔とポリアミド酸溶液の積層体を１１０℃４分間加熱し、自己支持性を有するゲルフィルムを得た。このゲルフィルムの残揮発分含量は３０ｗｔ％であり、イミド化率は９０％であった。このゲルフィルムをアルミ箔から剥がし、フレームに固定した。このゲルフィルムを３００℃、４００℃、５００℃で各１分間加熱して厚さ２５μｍのポリイミドフィルムを製造した。
【００４８】
［熱可塑性ポリイミド前駆体の作製法］
１，３−ビス（３−アミノフェノキシ）ベンゼンと３，３’−ジヒドロキシベンジジンをモル比４：１でＤＭＦに溶解し、撹拌しながら４，４’−（４，４’−イソプロピリデンジフェノキシ）ビス（無水フタル酸）を酸二無水物とジアミンが等モルになるように添加、約１時間撹拌し、固形分濃度２０ｗｔ％ポリアミド酸のＤＭＦ溶液を得た。
【００４９】
［積層体の作製］
上記製造法で作製した非熱可塑性ポリイミドフィルムをコアフィルムとして用い、その片面に上記製造法で作製した熱可塑性ポリイミドの前駆体であるポリアミド酸のＤＭＦ溶液をグラビヤコーターを用いて塗布した。
【００５０】
塗布後、加熱処理により溶媒乾燥、あるいはポリアミド酸のイミド化を行い、最終加熱温度３９０℃で非熱可塑性ポリイミド層と熱可塑性ポリイミド層からなる積層ポリイミドフィルムを作製した。尚、熱可塑性ポリイミド層の厚みは、乾燥イミド化後に４μｍとなるように塗布量を調整した。この熱可塑性ポリイミド樹脂の単体のシートについて測定したガラス転移温度は、１８０℃であった。
【００５１】
［無電解めっき方法］
下表に示すアトテック社製無電解めっきプロセスを用いて行った。
＜無電解めっき条件＞
【００５２】
【表１】

［電解銅めっき方法］
電解銅めっきは１０％硫酸中で３０秒間予備洗浄し、次に室温中で４０分間めっきを行なった。電流密度は２Ａ／ｄｍ²である。電解銅膜の厚さは１０μｍとした。
【００５３】
［レジスト層の形成方法］
液状感光性めっきレジスト（日本合成ゴム（株）社製、ＴＨＢ３２０Ｐ）をコーティングし、次いで高圧水銀灯を用いてマスク露光を行い、所望のＬ／Ｓを有するレジストパターンを形成した。
【００５４】
［表面形状の測定］
光波干渉式表面粗さ計ＺＹＧＯ社製ＮｅｗＶｉｅｗ５０３０システムを用いて下記の条件で樹脂表面の算術平均粗さを測定した。
【００５５】
（測定条件）
対物レンズ：５０倍ミラウ イメージズーム：２
ＦＤＡ Ｒｅｓ：Ｎｏｒｍａｌ
解析条件：
Ｒｅｍｏｖｅ：Ｃｙｌｉｎｄｅｒ
Ｆｉｌｔｅｒ：Ｈｉｇｈ Ｐａｓｓ
Ｆｉｌｔｅｒ Ｌｏｗ Ｗａｖｅｎ：０．００２ｍｍ、及び０．１ｍｍ
［微細配線間の金属エッチング残渣の確認］
ＳＥＭＥＤＸ Ｔｙｐｅ−Ｎ（日立製作所製）を使用して、配線間を観察し、金属元素のピークの有無を確認した。
【００５６】
［接着強度の測定］
ＩＰＣ―ＴＭ−６５０−ｍｅｔｈｏｄ．２．４．９に従い、パターン幅３ｍｍ、剥離角度９０度、剥離速度５０ｍｍ／ｍｉｎで測定した。
【００５７】
(実施例１)
銅箔 ＢＨＹ−２２Ｂ−Ｔ（１８μｍ、ジャパンエナジー社製）の粗化面（Ｒａ２＝０．２８μｍ）を上記製造方法で作製した積層体の熱可塑性ポリイミド層に重ね合わせ、温度３１０℃、線圧２０ｋｇｆ／ｃｍ、線速１．５ｍ／ｍｉｎの条件で熱ロールラミネートした。ラミネートした銅箔を塩酸／塩化第二鉄系エッチャントで完全に除去し、銅箔により粗化された樹脂表面を得た。次に、粗化された樹脂表面を過マンガン酸塩を用いた表面処理剤（デスミア液という。）で下表に示した条件で処理し、表面が粗化された熱可塑性ポリイミド樹脂層を有する本発明の積層体を得た。
＜デスミアによる処理条件＞
アトテック株式会社製過マンガン酸デスミアシステムによる。詳細条件は下表に示す。
【００５８】
【表２】

得られた表面形状を観察しその結果を表３に示した。
続いて、粗化された表面に無電解銅めっきおよび電解銅めっきを行い厚さ１８μｍの銅層を形成し、その常温での接着強度を測定した。その結果を表３にしめした。
更に形成した銅めっき層上にレジストパターンを形成し、露出しためっき銅を塩酸／塩化第二鉄系エッチャントで除去することによりＬ／Ｓ＝１０μｍ／１０μｍの配線を形成した。形成した配線を光学顕微鏡で観察し回路形成を確認し、配線間の銅のエッチング残りの有無についても確認した。その結果を表３に示した。
【００６１】
（実施例２）
銅箔をＴＱ−ＶＬＰ（９μｍ、三井金属社製）の粗化面（Ｒａ２＝０．２８μｍ）を使用した以外は、実施例１と同様の方法で、表面の処理、表面の解析、めっき銅層の形成、微細配線の形成を行い、回路形成性、接着性および金属のエッチング残りについて評価した。
【００６４】
（比較例１）
銅箔をＦ０−ＷＳ（９μｍ、古河電工社製）の粗化面（Ｒａ２＝０．２３μｍ）を使用した以外は、実施例１と同様の方法で、表面の処理、表面の解析、めっき銅層の形成、微細配線の形成を行い、回路形成性、接着性および金属のエッチング残りについて評価した。尚、使用した銅箔は、実施例１で使用した銅箔ＢＨＹ２２ＢＴと比較して、Ｒａ２はほぼ同じであったが、顕微鏡による目視では、波長の長い凹凸が多く存在していた。
【００６５】
（比較例２）
上記製造方法で作製した積層体の熱可塑性ポリイミド層の表面を、デスミア液で処理し、表面が粗化された熱可塑性ポリイミド樹脂層を有する積層体を得た。尚、デスミア液の処理条件は、各工程における処理時間を５分とした以外は実施例１と同様な方法で行った。
続いて、実施例１と同様の方法で、表面の解析、めっき銅層の形成、微細配線の形成を行い、回路形成性、接着性および金属のエッチング残りについて評価した。
【００６６】
（比較例３）
エポキシ系樹脂材料 ＡＢＦ−ＳＨ−９Ｋ（４５μｍ、味の素ファインテクノ社製）を１５０℃で３０分加熱した後に、樹脂表面をデスミア液で処理し、更に１７０℃３０分で樹脂を硬化させ、表面が粗化された樹脂を得た。尚、デスミア液の処理条件は、各工程における処理時間を１０分とした以外は実施例１と同様な方法で行った。続いて、実施例１と同様の方法で、表面の解析、めっき銅層の形成、微細配線の形成を行い、回路形成性、接着性および金属のエッチング残りについて評価した。
【００６７】
【表３】

【００６８】
【発明の効果】
少なくとも片面の算術平均粗さのカットオフ値０．００２ｍｍで測定した値Ｒａ１が、０．０５μｍ以上１μｍ以下であり、カットオフ値０．１ｍｍで測定した値Ｒａ２との比Ｒａ１／Ｒａ２が０．４以上１以下である表面形状を有する樹脂フィルムは、その表面上に形成された導体金属と優れた接着性を有しており、しかもＬ／Ｓ＝１０μｍ／１０μｍ程度の微細配線形成が可能であることから、本発明の樹脂フィルムで、接着性に優れ、更に耐熱性に優れるフレキシブルプリント配線板（ＦＰＣ）やビルドアップ回路基板等の回路基板の製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin film having a specific surface shape, a laminate and a printed wiring board using the same, and a method for producing the same. More specifically, a resin film that can be suitably used for the manufacture of printed wiring boards such as flexible printed wiring boards (FPC) and build-up circuit boards that require adhesion and heat resistance to a conductor layer made of metal, It is related with the laminated body and printed wiring board which use this, and its manufacturing method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the increase in functionality and miniaturization of electronic devices, there has been a demand for downsizing, high speed, light weight, high density, high reliability, and the like for electronic components used therein. Therefore, semiconductor device packaging methods and wiring materials or wiring components for mounting them have been required to have higher density, higher functionality, and higher performance. For this reason, recently, the wiring board has been multilayered and the additive method has been adopted as a method for forming a conductor circuit. The additive method is a method of forming a conductor circuit on a substrate by plating such as electroless plating, and is a method suitable for forming a high-density pattern. However, along with further thinning of the wiring width of the wiring board, the adhesion between the conductor circuit made of metal and the substrate made of the resin composition has become a problem.
[0003]
In order to ensure the adhesion between the metal formed by plating and the substrate made of the resin composition, the surface on which the plating is formed is arithmetically averaged as a method of improving the adhesion by roughening the surface of the resin composition. Although there is a film-like adhesive for electroless plating that can be firmly bonded with an adhesion strength of 10 N / cm or more between the metal and the resin by a method of roughening in a range of roughness Ra of 1 to 10 μm (see, for example, Patent Document 1) This is not a problem when the wiring width / wiring interval (hereinafter referred to as L / S) of the circuit wiring is large, but it is insufficient for future demands for further thinning. For example, when L / S is as small as 30 μm / 30 μm or less, if the surface roughness is large, circuit lines, which are high-density thin lines, are affected by irregularities on the substrate surface, which may be a problem.
However, since it is generally considered that when Ra is reduced, the adhesive strength is lowered, a material capable of forming excellent adhesiveness and fine wiring is strongly demanded.
[0004]
[Patent Document 1]
JP-A-11-26933 (paragraph number 006)
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is that the resin film has a surface roughness smaller than that of the conventional resin film, and is excellent in adhesion, can form fine wiring, and is excellent in heat resistance. It is to provide a resin film, a laminate, a printed wiring board using the same, and a method for manufacturing the same that can be suitably used for manufacturing a circuit board such as a flexible printed wiring board (FPC) or a build-up circuit board. .
[0006]
[Means for Solving the Problems]
As a result of diligent examination of the above problems, the present inventors have found that the projections having a specific range of wavelengths and heights are formed with a high density on the surface, and most of the irregularities formed on the surface are very fine. In spite of this, it has been found that the adhesiveness is also excellent. As a result, the resin film having a specific surface shape has excellent adhesiveness with the conductor metal formed on the surface, and as a result, it was found that fine wiring can be formed, and the present invention was completed. It came to do.
[0007]
That is, the resin film according to the present invention is characterized by having the following requirements in order to solve the above-mentioned problems.
1)A cut-off value of arithmetic average roughness of 0. 0 is obtained by treating the resin surface that has been surface-treated by the replica method using metal foil with a permanganate, a water-soluble liquid containing an organic alkali compound, or an organic solvent. The value Ra1 measured at 002 mm is 0.05 μm or more and 1 μm or less, and the ratio Ra1 / Ra2 to the value Ra2 measured at a cutoff value 0.1 mm is 0.4 or more and 1 or less, and the surface shape is at least on one side. A method for producing a printed wiring board, comprising at least a step of applying electroless plated copper to the surface of a polyimide resin film.
[0008]
According to the present invention, a flexible printed wiring board (FPC) having a small L / S, for example, a fine wiring having an L / S of 30 μm / 30 μm or less, excellent adhesion, and excellent heat resistance can be formed. It is possible to provide a resin film, a laminate, a printed wiring board using the same, and a method for manufacturing the same, which can be suitably used for manufacturing a circuit board such as a build-up circuit board.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the resin film of the present invention will be specifically described.
[0010]
Although it does not specifically limit as resin used for the resin film of this invention, The point which is excellent in heat resistance that polyethylene terephthalate, polyethylene naphthalate, aromatic polyamide (aramid), polybenzoxazole, polyimide, etc. contain resin In view of excellent balance of characteristics such as electrical characteristics and mechanical characteristics, it is particularly preferable to include polyimide resin, and in particular, heat having a glass transition temperature of 150 ° C. or higher and 300 ° C. or lower in terms of easy formation of fine irregularities. It is preferable to contain a plastic polyimide resin. When the glass transition temperature is less than 150 ° C., the printed wiring board produced from the material of the present invention tends to lose heat resistance. Workability tends to be impaired.
[0011]
Said thermoplastic polyimide resin can be manufactured by a well-known method. That is, it can be obtained by chemically or thermally imidizing polyamic acid, which is a polyimide precursor material. The polyamic acid, which is a precursor material of the polyimide resin used in the present invention, is usually obtained by using at least one acid dianhydride and at least one diamine as starting materials, and substantially equimolar amounts of both in an organic solvent. After the dissolution, it can be produced by stirring until polymerization is completed while controlling reaction conditions such as temperature.
[0012]
As said acid dianhydride, following General formula (1)
[0013]
[Chemical 1]

Wherein V is a divalent group selected from the group consisting of —O—, —CO—, —O—T—O—, and —COO—T—OCO—, and T is a divalent organic group. It is preferable to use an acid dianhydride represented by a group.) Because a polyimide resin having a suitable glass transition temperature (also referred to as a softening point) can be easily obtained. Among these, in particular, T in the general formula (1) from the viewpoint of excellent low water absorption and availability,
[0014]
[Chemical formula 2]

And a group represented by the general formula (2)
[0015]
[Chemical 3]

(Wherein Z is -C_QH_2Q-, -C (= O)-, -SO₂A divalent group selected from the group consisting of-, -O-, and -S-, and Q is an integer of 1-5. It is preferable to use at least one acid dianhydride selected from the group of acid dianhydrides represented by
[0016]
Examples of the acid dianhydride represented by the general formula (1) include the following. 4,4 '-(4,4'-isopropylidenediphenoxy) bisphthalic anhydride, 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3', 4,4'-tetracarboxylic acid Anhydride, p-phenylenebis (trimellitic acid monoester anhydride), 4,4'-biphenylenebis (trimellitic acid monoester anhydride), 1,4-naphthalenebis (trimellitic acid monoester anhydride), 1,2-ethylenebis (trimellitic acid monoester anhydride), 1,3-trimethylenebis (trimellitic acid monoester anhydride), 1,4-tetramethylenebis (trimellitic acid monoester anhydride), 1,5-pentamethylenebis (trimellitic acid monoester anhydride), 1,6-hexamethylenebis (trimellitic acid monoester anhydride) Can be mentioned.
[0017]
Among the acid dianhydrides, 4,4 ′-(4,4′-isopropylidenediphenoxy) bisphthalic anhydride, 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4 , 4'-tetracarboxylic dianhydride has a suitable glass transition temperature, and a thermoplastic polyimide resin having a balanced property such as low water absorption and heat resistance such as heat decomposability can be obtained. Is particularly preferred.
Examples of the acid dianhydride other than the general formula (1) include the following acid dianhydrides. Pyromellitic acid, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene Tetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3 ', 4,4'-dimethyldiphenylsilane tetracarboxylic acid Anhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropanoic dianhydride, 4,4′-hexafluoroisopropyl Dendiphthalic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, p-phenylenediphthalic anhydride Etc. including but not limited to.
[0018]
These acid dianhydrides may be used alone or in combination of two or more at any ratio.
[0019]
The polyimide resin has the following general formula (3) as a diamine component.
[0020]
[Formula 4]

Wherein Y is -C (= O)-, -SO₂-, -O-, -S-,-(CH₂)_m-, -NHCO-, -C (CH_Three)₂-, -C (CF_Three)₂-, -C (= O) O-, or a single bond is shown. R₂Is hydrogen, a halogen group or an alkyl group having 1 to 4 carbon atoms, and m and r are integers of 1 to 5. The polyimide resin obtained by using at least one kind of diamine represented by) is easy to control the softening point (or glass transition temperature), excellent in heat resistance, and easy to obtain a low water-absorbing polyimide resin. Is preferable.
[0021]
In order to improve various properties such as adhesiveness, heat resistance, and workability, the above polyimide resin has epoxy resin, cyanate ester resin, bismaleimide resin as long as various properties such as heat resistance and low hygroscopicity are not impaired. Thermosetting resins such as bisallyl nadiimide resin, phenol resin, acrylic resin, methacrylic resin, hydrosilyl cured resin, allyl cured resin, unsaturated polyester resin, and allyl group, vinyl group at the side chain or terminal of the polymer chain, The side chain reactive group type thermosetting polymer having a reactive group such as an alkoxysilyl group and a hydrosilyl group can be mixed singly or in appropriate combination.
[0022]
In the resin film of the present invention, the value Ra1 measured with a cutoff value of 0.002 mm of arithmetic average roughness is 0.05 μm or more and 1 μm or less, and the ratio Ra1 / with the value Ra2 measured with a cutoff value of 0.1 mm. Ra2 has a surface shape of 0.4 or more and 1 or less on at least one side.
[0023]
The arithmetic average roughness Ra of the present invention is defined in JIS B 0601 (revised on February 1, 1994). In particular, the numerical value of the arithmetic average roughness Ra of the present invention is a numerical value obtained by observing the surface with an optical interference type surface structure analyzer. The cutoff value of the present invention is described in the above JIS B 0601, and indicates a wavelength set when a roughness curve is obtained from a cross-sectional curve (measured data). That is, the value Ra measured with a cut-off value of 0.002 mm is an arithmetic average roughness calculated from a roughness curve obtained by removing irregularities having a wavelength longer than 0.002 mm from measured data. Therefore, when there is no unevenness having a wavelength shorter than 0.002 mm, the value Ra measured with a cutoff value of 0.002 mm is 0 μm.
[0024]
As a method for forming irregularities on the surface of the resin, a method of physically removing a part of the resin by sandblasting, polishing or the like can be preferably used. When the resin has thermoplasticity, embossing can also be preferably used. In embossing, it is possible to form irregularities on the resin surface by bringing the resin into contact with a metal material having irregularities on the surface at a temperature equal to or higher than the glass transition temperature (or softening point) of the resin. At this time, it is preferable to involve heating and pressurization, and it is preferable to process under conditions that allow appropriate irregularities to be formed. In addition, after bringing the roughened surface of the metal foil into contact with the resin film, the metal is heated and pressure-bonded by a press method or the like at a temperature equal to or higher than the softening point of the resin, and then the metal foil is physically or peeled off. A method called a replica method, which is removed, can also be preferably used.
[0025]
As another method, when manufacturing a resin film, a method of forming a film by mixing fine particles with a resin can be used.
[0026]
Whichever method is used, it is preferable that the sandblasting process and the polishing process are performed under conditions that allow appropriate irregularities to be formed.
[0027]
In addition, as the surface treatment of the present invention, a resin surface treatment for removing a part of the resin surface layer can be preferably applied. This surface treatment method is intended to dissolve an appropriate thickness of the surface of the resin, and it is possible to improve the adhesion to the metal. The reason for this is not clear, but by this surface treatment, irregularities are formed on the resin surface, and / or the chemical layer changes by removing the surface layer of the resin by dissolution, It is presumed to have a positive effect on the adhesion of Here, “partially removed” represents a state in which the entire surface layer of the resin is uniformly removed, or a state in which the surface layer is non-uniformly, that is, removed in an island shape or remains in an island shape.
[0028]
Specifically, as a surface treatment for removing a part of the surface layer of the resin, a method of treating in a gas phase such as corona discharge, atmospheric pressure plasma, vacuum plasma, electron beam, laser, RIE, or treatment with a liquid that dissolves the resin. A liquid phase process is mentioned. These treatments are considered to have the effect of forming a minute uneven surface on the resin surface and firmly bonding the electroless plating film, and also the effect of chemically activating the resin surface. Among these treatments, corona discharge, atmospheric pressure plasma, vacuum plasma, a method of treating with a gas phase of electron beam, and a method of treating with a liquid phase are industrially simple and preferably carried out. The liquid phase treatment is not particularly limited as long as it dissolves the resin and achieves the object of the present invention. Specifically, a permanganate, a water-soluble liquid containing an organic alkali compound, an organic solvent, or the like, which is widely used industrially, particularly used in a desmear process or resin etching in printed wiring board production, is preferably used. Particularly when the resin is a polyimide resin, the organic solvent to be dissolved is an amide solvent, that is, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc., and N, N-dimethylform Amides are particularly preferably used.
[0029]
As described above, the resin surface treatment method is divided into “surface treatment for forming irregularities on the surface of the resin” and “surface treatment for removing a part of the resin surface layer”, together with the specific method, but these are combined. I also found that it was effective. Specifically, “surface treatment for forming irregularities on the surface of the resin” and “surface treatment for removing part of the surface layer of the resin” are used in combination, and various combinations are effective. Among these, it is particularly effective to use both “surface treatment for forming irregularities on the surface of the resin” and liquid phase treatment for dissolving the resin. Among them, the surface of the resin subjected to surface treatment using a metal foil is permanganese. It is particularly effective to treat with an acid salt, an organic alkali compound or an organic solvent.
[0030]
In any method, the value Ra1 measured at a cutoff value of 0.002 mm of arithmetic average roughness is 0.05 μm or more and 1 μm or less, and the ratio Ra1 to the value Ra2 measured at a cutoff value of 0.1 mm. / Ra2 is controlled to be 0.4 or more and 1 or less, preferably, Ra1 is 0.1 or more and 0.8 μm or less, Ra1 / Ra2 is 0.5 or more and 1 or less, particularly Ra1 is preferably 0.2 or more and 0.6 μm or less, and Ra1 / Ra2 is preferably 0.6 or more and 1 or less. Here, Ra2 is a numerical value obtained by removing irregularities larger than 100 μm. However, irregularities having a wavelength of 100 μm or more have a large ratio of film wrinkles and curls that occur when setting a sample during surface shape observation. It is a numerical value that is considered to be suitable for removing irregularities that are not inherent to the film. On the other hand, Ra1 is a value obtained by removing irregularities exceeding 2 μm, but when the present inventors increase these, for example, when forming a fine wiring with L / S of 30 μm / 30 μm or less, preferably 10 μm / 10 mμm It was found that the wiring formability tends to decrease. Further, it has also been found that the unevenness of 2 μm or less has a tendency to lower the adhesiveness unless it has a certain height, that is, when the arithmetic average roughness value is 0.05 μm or more and 1 μm or less.
[0031]
That is, if the ratio of Ra1 / Ra2 is less than 0.4, it is difficult to form a fine circuit because there are many irregularities having wavelengths exceeding 2 μm and not more than 100 μm. Moreover, although Ra1 / Ra2 does not exceed 1, since it is a surface which has many fine unevenness | corrugations which have a wavelength of 2 micrometers or less as it is close to 1, it is preferable as a surface which can form fine wiring. Also, if Ra1 is less than 0.05 μm, the height of the formed unevenness is insufficient and the adhesiveness is poor, and if it exceeds 1 μm, the height of the unevenness becomes too large, resulting in a fine circuit. It becomes difficult to form.
[0032]
In order to make the surface shape within the above range, it is important to form the surface shape under processing conditions suitable for the resin film used.
[0033]
For example, when part of the resin surface is dissolved with a chemical solution, the type of the chemical solution, the concentration, and a processing material such as a combination of a plurality of chemical solutions, a processing temperature with the chemical solution, It is necessary to select processing conditions such as processing time, but it is important to combine materials and conditions used for processing, particularly in accordance with the characteristics of the resin film.
[0034]
When the resin film has thermoplasticity, it is preferable to form fine irregularities by embossing or a replica method. If it is a replica method, it is necessary to select the type of metal to be used (processing material such as surface roughness, surface shape, etc., and processing conditions such as temperature, pressure, time during pressing, In particular, it is important to combine the materials and conditions used for processing according to the properties of the thermoplastic resin film, and when embossing or forming a fine uneven surface using a thermoplastic resin. It is natural to use metal rolls and metal foils, and metal rolls and copper foils having suitable irregularities. However, in order to form a suitable surface shape, metal rolls and metal foils are formed on thermoplastic resin materials. The temperature and pressure during pressing are particularly important.
[0035]
Specifically, the press temperature is in the range of −100 ° C. to + 180 ° C., preferably −50 ° C. to 150 ° C., of the glass transition temperature of the thermoplastic resin. The pressure is in the range of 10 kgf / cm to 200 kgf / cm, preferably 20 kgf / cm to 150 kgf / cm, and the line speed is 0.5 m / min to 5 m / min, preferably 1 m / min to 3 m / min. Although it is preferable to carry out, it is important to set suitable conditions in accordance with the characteristics of the thermoplastic resin material (the fluidity of the resin by heating, the glass transition temperature, and the elastic modulus during heating).
[0036]
The resin film of the present invention can be a multilayer resin film for the purpose of supplementing various properties such as mechanical properties, heat resistance and processability of a resin film having a specific surface. In the case of a multilayer resin film, it is preferable that a polyimide resin is contained in all layers in terms of an excellent balance of characteristics such as insulation characteristics, thermal characteristics, and mechanical characteristics.
[0037]
In order to provide the lamination property of the adhesive layer, it is possible to have a resin layer having a lower softening point or melting point than the resin having the surface of the present invention on the surface opposite to the surface having the surface shape of the present invention. is there.
[0038]
The method for forming a metal layer to be a conductor layer on the surface having a specific surface shape of the resin film of the present invention is not particularly limited, but wet plating methods such as electroless plating methods and electroplating methods, sputtering methods and vapor deposition methods. Examples include a dry plating method such as a method, and a wet plating method that is excellent in cost is particularly preferable. Alternatively, the metal foil may be bonded through an adhesive.
[0039]
As a method of forming an electronic circuit on the surface having a specific surface shape of the resin film of the present invention, a method of forming a circuit by forming a metal layer on the entire surface and removing a part of the metal layer by etching, Examples include a method of forming a circuit by forming a plating resist layer on the surface, exposing and developing, and then laminating a metal layer on the exposed surface of the present invention by plating.
[0040]
It is also possible to produce a multilayer circuit board using the resin film of the present invention. In the method for producing a multilayer circuit board, a resin film having a softening point or a melting point lower than that of the resin having the surface on the surface opposite to the surface having the specific surface shape of the present invention is used. Can do. In other words, a substrate having a circuit formed in advance is brought into contact with a resin layer having a softening point or melting point lower than that of a resin having a specific shape on the surface of the present invention, and then pressed and laminated by pressing or laminating and then specified. It can be manufactured by forming a circuit on a surface having the following shape.
[0041]
Next, the specific example of the manufacturing method of the printed wiring board using the resin film of this invention and a laminated body is demonstrated. In the method for producing a printed wiring board, electroless plated copper is applied to the surface of the resin film of the present invention having a specific surface shape. For electroless plating, chemical plating using a palladium catalyst or direct plating using palladium, carbon, or the like can be used. Further, a resist film is formed on the electrolessly plated copper, and the resist film in a portion where a circuit is to be formed is removed by exposure and etching. Next, a circuit is formed by a pattern plating method using electrolytic copper using the portion where the electroless plating film is exposed as a feeding electrode. Next, the resist portion is removed, and unnecessary portions of the electroless plating layer are removed by etching to form a circuit. This method is called a semi-additive method.
[0042]
As a method other than the above method, the following printed wiring board manufacturing method can be exemplified. First, similarly to the above, an electroless plated copper layer is formed on the surface of the resin film of the present invention having a specific surface shape. Next, electrolytic plating copper is applied, a resist film is formed on the surface of the electrolytic copper plating layer, the resist film where the circuit is not formed is removed by an exposure process and development, and then an unnecessary metal layer is removed by etching to form a circuit. To do. This method is called a subtractive method.
[0043]
In the above method, as a method for forming the metal layer, a sputtering method can be used instead of electroless plating. When manufacturing multilayer printed wiring boards, flexible printed wiring boards based on resin films such as polyimide films with circuits formed on the surface, rigid boards such as glass epoxy group bismaleimide-triazine substrates, etc. Similar to the above-described method for manufacturing a printed wiring board after laminating the resin film of the present invention on a substrate with a surface having a specific surface shape as an outer layer via a thermoplastic or thermosetting adhesive By this method, it is also possible to form a circuit on the resin film of the present invention.
[0044]
In the method for producing a multilayer printed wiring board described above, it is also possible to form a via hole that penetrates the resin film layer of the present invention and leads to a lower wiring board circuit after laminating the resin film of the present invention. The via hole is formed by a drilling method using a carbon dioxide laser, a UV-YAG laser, punching, drilling, or the like. When forming a small via hole, a drilling method using a laser is preferably used. After forming the via hole, a desmear process is performed to remove smear mainly composed of carbides due to the heat of the resin formed in and around the via hole. In this desmear process, a known method can be used, and a dry process such as a wet process using a permanganate or plasma can be used. The various laminates of the present invention have durability against a permanganate desmear process widely used in the production of printed wiring boards and can be preferably used. Next, it is possible to form a circuit after electrolessly plated copper is applied to the surface of the resin layer and the inside of the via hole by a method similar to the method for manufacturing a printed wiring board. In addition to the via hole, a through hole called a through hole that penetrates the entire laminated body including the underlying wiring board circuit may be formed.
[0045]
Since the resin film according to the present invention has fine irregularities on its surface, for example, it is possible to form a fine circuit having an L / S of about 10 μm / 10 μm, and the surface irregularities are small. Regardless, it is excellent in adhesiveness with the conductor layer formed on the surface. Therefore, it is possible to sufficiently eliminate the problems caused by the conventional film adhesive, and as a result, it is suitably used for the production of circuit boards such as flexible wiring boards (FPC) and build-up multilayer circuit boards. be able to. In addition, it goes without saying that the resin film according to the present invention may contain components other than those described above as long as the characteristics are not deteriorated. Similarly, it goes without saying that the resin film according to the present invention may include steps other than those described above.
[0046]
【Example】
EXAMPLES The effects of the present invention will be specifically described with reference to the following examples. However, the present invention is not limited to the following examples, and those skilled in the art will recognize various effects without departing from the scope of the present invention. Changes, modifications, and alterations can be made. In addition, preparation of various laminated bodies in Examples, synthesis / production of adhesive layers, lamination, electroless plating, and various measurements / evaluations were performed by the following methods.
[0047]
[Production method of non-thermoplastic polyimide film]
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride / p-phenylenebis (trimellitic acid monoester anhydride) / p-phenylenediamine / 4,4′-diaminodiphenyl ether in a molar ratio of 4 A 90 wt. Of DMF (N, N-dimethylformamide) solution of polyamic acid synthesized at a ratio of / 5/7/2 was mixed with a conversion agent consisting of 17 g of acetic anhydride and 2 g of isoquinoline, stirred, and defoamed by centrifugation. Thereafter, the film was cast on an aluminum foil at a thickness of 700 μm. The process from stirring to defoaming was performed while cooling to 0 ° C. The laminate of the aluminum foil and the polyamic acid solution was heated at 110 ° C. for 4 minutes to obtain a gel film having self-supporting properties. This gel film had a residual volatile content of 30 wt% and an imidization ratio of 90%. This gel film was peeled off from the aluminum foil and fixed to the frame. This gel film was heated at 300 ° C., 400 ° C., and 500 ° C. for 1 minute each to produce a polyimide film having a thickness of 25 μm.
[0048]
[Method for producing thermoplastic polyimide precursor]
1,3-bis (3-aminophenoxy) benzene and 3,3′-dihydroxybenzidine are dissolved in DMF at a molar ratio of 4: 1 and 4,4 ′-(4,4′-isopropylidenediphenoxy is stirred with stirring. ) Bis (phthalic anhydride) was added so that the acid dianhydride and diamine were equimolar and stirred for about 1 hour to obtain a DMF solution of a solid content concentration of 20 wt% polyamic acid.
[0049]
[Production of laminate]
The non-thermoplastic polyimide film produced by the above production method was used as a core film, and a DMF solution of polyamic acid, which is a precursor of the thermoplastic polyimide produced by the above production method, was applied on one side using a gravure coater.
[0050]
After coating, solvent drying or polyimidic acid imidation was performed by heat treatment, and a laminated polyimide film composed of a non-thermoplastic polyimide layer and a thermoplastic polyimide layer was produced at a final heating temperature of 390 ° C. The coating amount was adjusted so that the thickness of the thermoplastic polyimide layer was 4 μm after dry imidization. The glass transition temperature measured for a single sheet of this thermoplastic polyimide resin was 180 ° C.
[0051]
[Electroless plating method]
The electroless plating process manufactured by Atotech Co. shown in the following table was used.
<Electroless plating conditions>
[0052]
[Table 1]

[Electrolytic copper plating method]
The electrolytic copper plating was pre-cleaned in 10% sulfuric acid for 30 seconds and then plated at room temperature for 40 minutes. Current density is 2 A / dm²It is. The thickness of the electrolytic copper film was 10 μm.
[0053]
[Method for forming resist layer]
A liquid photosensitive plating resist (manufactured by Nippon Synthetic Rubber Co., Ltd., THB320P) was coated, and then a mask exposure was performed using a high-pressure mercury lamp to form a resist pattern having a desired L / S.
[0054]
[Surface shape measurement]
The arithmetic average roughness of the resin surface was measured under the following conditions using a New View 5030 system manufactured by ZYGO.
[0055]
(Measurement condition)
Objective lens: 50x Mirau Image zoom: 2
FDA Res: Normal
Analysis conditions:
Remove: Cylinder
Filter: High Pass
Filter Low Waven: 0.002mm and 0.1mm
[Confirmation of metal etching residue between fine wiring]
Using SEMEDX Type-N (manufactured by Hitachi, Ltd.), the space between the wirings was observed, and the presence or absence of a metal element peak was confirmed.
[0056]
[Measurement of adhesive strength]
IPC-TM-650-method. According to 2.4.9, measurement was performed at a pattern width of 3 mm, a peeling angle of 90 degrees, and a peeling speed of 50 mm / min.
[0057]
(Example 1)
The roughened surface (Ra2 = 0.28 μm) of copper foil BHY-22B-T (18 μm, manufactured by Japan Energy Co., Ltd.) was superposed on the thermoplastic polyimide layer of the laminate produced by the above production method, temperature 310 ° C., linear pressure Heat roll lamination was performed under the conditions of 20 kgf / cm and a linear velocity of 1.5 m / min. The laminated copper foil was completely removed with a hydrochloric acid / ferric chloride etchant to obtain a resin surface roughened with the copper foil. Next, the surface of the roughened resin is treated with a surface treatment agent using a permanganate (referred to as a desmear liquid) under the conditions shown in the table below, and the surface has a roughened thermoplastic polyimide resin layer. A laminate of the present invention was obtained.
<Processing conditions by desmear>
According to the permanganate desmear system manufactured by Atotech Co., Ltd. Detailed conditions are shown in the table below.
[0058]
[Table 2]

The obtained surface shape was observed and the results are shown in Table 3.
Subsequently, electroless copper plating and electrolytic copper plating were performed on the roughened surface to form a copper layer having a thickness of 18 μm, and the adhesive strength at room temperature was measured. The results are shown in Table 3.
Further, a resist pattern was formed on the formed copper plating layer, and the exposed plated copper was removed with a hydrochloric acid / ferric chloride-based etchant to form a wiring of L / S = 10 μm / 10 μm. The formed wiring was observed with an optical microscope to confirm circuit formation, and the presence or absence of copper etching residue between the wirings was also confirmed. The results are shown in Table 3.
[0061]
(Example2)
Surface treatment, surface analysis, plated copper in the same manner as in Example 1 except that the roughened surface (Ra2 = 0.28 μm) of TQ-VLP (9 μm, Mitsui Metals) was used as the copper foil. Formation of layers and formation of fine wiring were carried out, and the circuit formability, adhesion and metal etching residue were evaluated.
[0064]
(Comparative Example 1)
Surface treatment, surface analysis, plated copper in the same manner as in Example 1 except that the roughened surface (Ra2 = 0.23 μm) of F0-WS (9 μm, manufactured by Furukawa Electric) was used as the copper foil. Formation of layers and formation of fine wiring were carried out, and the circuit formability, adhesion and metal etching residue were evaluated. In addition, although the used copper foil compared with copper foil BHY22BT used in Example 1 as Ra2, it was substantially the same, but the visual observation with a microscope had many unevenness | corrugations with a long wavelength.
[0065]
(Comparative Example 2)
The surface of the thermoplastic polyimide layer of the laminate produced by the above production method was treated with a desmear liquid to obtain a laminate having a thermoplastic polyimide resin layer having a roughened surface. The processing conditions for the desmear solution were the same as in Example 1 except that the processing time in each step was 5 minutes.
Subsequently, analysis of the surface, formation of a plated copper layer, and formation of fine wiring were performed in the same manner as in Example 1 to evaluate circuit formability, adhesion, and metal etching residue.
[0066]
(Comparative Example 3)
Epoxy resin material ABF-SH-9K (45 μm, manufactured by Ajinomoto Fine Techno Co., Ltd.) was heated at 150 ° C. for 30 minutes, then the resin surface was treated with desmear liquid, and the resin was further cured at 170 ° C. for 30 minutes. A roughened resin was obtained. The processing conditions for the desmear solution were the same as in Example 1 except that the processing time in each step was 10 minutes. Subsequently, analysis of the surface, formation of a plated copper layer, and formation of fine wiring were performed in the same manner as in Example 1 to evaluate circuit formability, adhesion, and metal etching residue.
[0067]
[Table 3]

[0068]
【The invention's effect】
A value Ra1 measured with a cut-off value of 0.002 mm of arithmetic average roughness of at least one side is 0.05 μm or more and 1 μm or less, and a ratio Ra1 / Ra2 to a value Ra2 measured with a cut-off value of 0.1 mm is 0. The resin film having a surface shape of 4 or more and 1 or less has excellent adhesiveness with the conductor metal formed on the surface, and can form fine wiring of about L / S = 10 μm / 10 μm. Therefore, with the resin film of the present invention, it is possible to produce a circuit board such as a flexible printed wiring board (FPC) or a build-up circuit board having excellent adhesiveness and heat resistance.

Claims (1)

A cut-off value of arithmetic average roughness of 0. 0 is obtained by treating the resin surface that has been surface-treated by the replica method using metal foil with a permanganate, a water-soluble liquid containing an organic alkali compound, or an organic solvent . the value measured at 002Mm Ra1 is, it is 0.05μm or 1μm or less, the ratio Ra1 / Ra2 of the value Ra2 measured at a cut-off value 0.1mm was 0.4 or more and 1 or less, and even less surface shape A method for producing a printed wiring board, comprising at least a step of applying electroless plated copper to the surface of a polyimide resin film on one side .