JP3783785B2

JP3783785B2 - Method for manufacturing anisotropic conductive resin film adhesive and method for connecting between fine circuits

Info

Publication number: JP3783785B2
Application number: JP09633794A
Authority: JP
Inventors: 泰史後藤; 功塚越; 共久太田
Original assignee: Hitachi Chemical Co Ltd; Showa Denko Materials Co Ltd
Current assignee: Showa Denko Materials Co Ltd
Priority date: 1994-05-10
Filing date: 1994-05-10
Publication date: 2006-06-07
Anticipated expiration: 2021-06-07
Also published as: JPH07302667A

Description

【０００１】
【産業上の利用分野】
本発明は、樹脂フィルム状接着材中に分散した導電性粒子を介して、厚み方向にのみ導電性を有する異方導電性の樹脂フィルム状接着材の製造法及び該製造法で得られる接着材を用いた微細回路間の接続方法に関するものである。
【０００２】
【従来の技術】
電子部品の小形薄形化に伴い、これらに用いる回路は高密度化、高精細化している。これら微細回路の接続は従来の半田、ゴムコネクタ等では対応が困難であることから、最近では異方導電性の接着材や膜状物からなる接続部材が多用されるようになってきた。この方法は、相対峙する回路間に導電性材料を所定量含有した絶縁性樹脂よりなる電気的な接続部材層を設け、加圧又は加熱加圧手段を講じることによって、上下回路間の電気的接続と同時に隣接回路間には絶縁性を付与するものである。また、前記の絶縁性樹脂を接着材として、相対峙する回路間の電気的な接続と同時に回路間の接着固定をするものも用いられている。このような、厚み方向にのみ導電性を有する異方導電性の樹脂フィルム状接着材に関する先行技術文献としては、例えば、特開昭51-21192号公報に開示されているように、導電性粒子を非導電性ベースにより互いに接触しない状態に保持した混合体を導電性粒子の大きさにほぼ等しい厚さのシート状に成形し、導電性粒子を介してシート状の厚み方向にのみ導電性を有する構造としたものがある。
【０００３】
これらの樹脂フィルム状接着材の成形方法は、液状の樹脂に導電性粒子を均一分散したものをバーコーター等により一定厚さで流延した後、乾燥又は硬化し、所望の厚さの接着材を得るものである。また、導電性粒子の濃度をフィルムの厚さ方向で異なる構成にしたものとして、透孔を設けたフィルムに導電性粒子を入れた後、フィルムと導電性粒子とを接着固定する方法や、特開平２−117980号公報、特開平５-67480号公報に開示されているように導電性粒子をフィルム状の接着材に埋め込む方法もある。この厚み方向にのみ導電性を有する異方導電性の樹脂フィルム状接着材において、フィルムの単位面積当りの導電点を多くし、高分解能化を図るには、フィルム中の導電性粒子の配合量を増加する必要がある。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記の従来技術である液状の樹脂及び導電性粒子の均一混合物を流延してフィルム化する方法では、高精細電極に対応するために導電性粒子の配合量を増加しようとすると、導電性粒子を分散した液状樹脂の粘度が上昇して流動性が損なわれるために、バーコーター等により一定厚さで流延することが困難になり、導電性粒子の配合量を少なくせざるを得ない。更に、このようなフィルム中に均一に導電性粒子が分散したフィルムでは、高精細回路に対応するために導電性粒子の配合量を増加するのに伴い、接続する回路間に挟持されず導通に寄与しない隣接回路間の導電性粒子量も増え、製造コストが増加してしまう問題点がある。
【０００５】
また、透孔を設けたフィルムに導電性粒子を入れた後にフィルムと導電性粒子とを接着固定する方法においては、フィルムに微小な孔を多数設けることは生産性やコストの面で実施することが困難である。更に、導電性粒子をフィルム状の接着材に埋め込む方法では、接着材の粘度が液状程度に十分に低くなければ導電性粒子表面に接着材が十分に濡れることが出来ず、導電性粒子とフィルム状接着材との接着性が劣り、導電性粒子が脱落し易くなる。液状のフィルム状樹脂を用いたとき、支持体上に保持した導電性粒子を液状の接着材面に転写する工程で支持体上に接着材が付着することが避けられず、フィルム化が困難になる。
【０００６】
また、導電性粒子の充填量を多くした場合に、導電性粒子間の空隙に過不足なく接着材を充填することが困難になり、導電性粒子の充填量と導電性粒子を充填する前のフィルム状接着材の厚さとの関係を厳密に規定しなければならない。フィルム状接着材の厚みが厚いと前述の支持体への接着材の付着は避けられず、薄いとフィルムとしての強度が得られなかったり、粒子が脱落したりする。本発明は、このような状況に鑑みてなされたもので、微細な電極でも電気的な接続が得られる異方導電性樹脂フィルム状接着材の新規な製造法を提供しようとするものである。
【０００７】
【課題を解決するための手段】
本発明は、面方向に均一分散した導電性粒子を介して厚み方向にのみ導電性を有する異方導電性樹脂フィルム状接着材を製造する方法において、粘着材面上に導電性粒子の粒径以上の厚さに導電性粒子層を設けた後、該導電性粒子層を粘着材面に押圧し、導電性粒子を粘着材面に粘着固定し、粘着材と非相溶なフィルム形成接着材を導電性粒子間に充填した後、該フィルム形成接着材から粘着材を剥離する異方導電性樹脂フィルム状接着材の製造法、及び該製造法で得られる接着材を用いた微細回路間の接続方法に関する。即ち、本発明は、導電性粒子を粘着材面に散布することにより、粘着材面に導電性粒子を面方向に配列した状態で固定した後、粘着材と非相溶なフィルム形成接着材溶液を塗布し、導電性粒子間に充填する工程を有する、フィルムの厚さ方向にのみ導電性を有する樹脂フィルム状接着材の製造法である。
【０００８】
本発明では、治具として粘着材面上に透孔を有するフィルム又は網（以下、本治具をマスクと呼ぶ）を載置し、導電性粒子を散布すること（請求項２）によって、透孔内の粘着材面にだけ導電性粒子を付着させることが出来、フィルムの面内で所望の位置に導電性粒子を配置することが出来、面内で回路の電極位置だけに導電性粒子を配置することが可能となる。また、導電性粒子を粘着材面に散布した後、ゴムロール等を用いて導電性粒子を粘着材面に押圧し（請求項１）、導電性粒子の面方向の配列密度を向上することが可能である。
【０００９】
本発明の導電性粒子を粘着材面に固定する方法として、導電性粒子をロール状等の帯電体上に静電気により保持した後、この帯電体を粘着材面に押圧し、導電性粒子を粘着材面に転写すること（請求項３）により、一定量の導電性粒子を連続的に配列することが可能となる。このとき、帯電体上にマスクを載置し、導電性粒子を散布すること（請求項４）により、透孔内の帯電体面にのみ導電性粒子を付着させることが出来、フィルムの面内で所望の位置に導電性粒子を配置することが可能となる。また、導電性粒子及び粘着材面を異なる電荷に帯電させ、導電性粒子を粘着材面に吸着した後固定する方法(請求項５)でも、一定量の導電性粒子を連続的に配列することが可能となる。この場合も、粘着材上にマスクを載置し、導電性粒子を散布することにより、透孔内の粘着材面にのみ導電性粒子を付着させることが出来、フィルムの面内で所望の位置に導電性粒子を配置することが可能となる。
【００１０】
上記の導電性粒子を静電気力により粘着材面に固定する方法では、導電性粒子を繊維状の導電体とすること（請求項６）により、フィルム面に垂直に繊維の長軸が配列した異方導電性樹脂フィルム状接着材が出来、導電体が高密度に充填して導電性を向上することが可能である。導電性粒子又は繊維状導電体の表面を加熱又は加圧により除去し得る熱可塑性樹脂等の電気絶縁層であらかじめ表面を被覆したものを用いること（請求項７）により、これがフィルムの面方向に細密に充填した状態であっても、面方向の絶縁性を保つことが可能になる。また、電極間の位置合わせをして、フィルム形成接着材の厚さを相対峙した両回路を密接させたときに生ずる空間の体積にほぼ等しい体積を持つようにすること（請求項８）により、接続部に空隙がなく、接着材のはみ出しも少ない接続体が出来、湿度の浸入による接続信頼性の低下や接続時における導電性粒子の流動による隣接回路間の短絡を防止することが出来る。
【００１１】
また、接着材の塗工厚さを厚くして導電性粒子の層上に接着材層を設けた２層構造のフィルムとすること（請求項９）が出来る。このフィルムは導電性粒子の無い接着材層の方が導電性粒子を充填した層よりも接続時の溶融粘度が低いので、電極間の凹部に接着材層が流入し易く、導電性粒子が流入し難い。よって、隣接した電極間の短絡を極めて少なくし、導電に寄与する粒子数を増加させることが出来る。更に、この接続時に接着材層側から加熱して圧接すると（請求項１０）、接着材層側が先に溶融して電極間の凹部に流入するので、前述の効果を向上することが出来る。
【００１２】
本発明で用いられる導電性粒子の種類は特に限定されるものではなく、金属粒子やガラス、セラミック、プラスチック等の粒子の表面に金属のめっき層を形成した粒子を単独又は複合して用いることが出来る。各々個々の導電性粒子が小粒径の導電性粒子の凝集体からなるものも用いることが出来る。また、粒径は接続する回路の細かさにより選択されるが、各粒子の粒径は出来るだけ均一である必要がある。形状は微細電極の接続のために粒子の大きさを均一にする上で真球状が好ましい。一般的に非常に微細な電極を接続するときには、真球状のプラスチック粒子表面に金属めっき層を形成した粒子を用い、耐熱性等で金属粒子を用いるときは、より真球状に近いガスアトマイズ法や回転電極アトマイズ法で作製した粒子を用いる方が好ましい。但し、水アトマイズ法で作製された金属粉のように不定形の粒子でも、分級により粒径を揃えることで導電性粒子として用いることが出来る。
【００１３】
また、本発明で用いる繊維状導電体は長軸を持った形状を有しており、製法に左右されない。即ち、繊維状導電体は導電性粒子のうちの長軸を持つものということができる。繊維状導電体の種類も特に限定されるものではないが、一般に市販されている金属の短繊維、ガラス繊維表面に金属めっきをしたもの、又は炭素繊維等を用いることが出来る。繊維の径や長さは接続する電極の細かさにより選択されるが、繊維の長さは揃っている方が導電性が良く、繊維の径は小さく均一である方がより微細な電極に用いることが出来る。また、導電性粒子の固定位置を制御するマスクを用いない場合において、面方向の絶縁性を確保するためには導電性粒子や繊維状導電体の粘着材面への散布量を適切にしなければならない。導電性粒子や繊維状導電体同士は互いに接する部分が増えると共に、面方向の絶縁性が損なわれる。よって、高密度の導電点を得るには個々の導電性粒子や繊維状導電体の表面に電気絶縁層（絶縁層）を設けることで達成出来る。
【００１４】
絶縁層はフィルム形成樹脂に相溶しない樹脂を含み、単一層構造や多層構造とすることが出来る。ここで、相溶しないとは、相互の樹脂が親和性を有さず均一化した混和物を形成しないことで、一般に用いられる相溶性の目安としてはＳＰ値があり（溶解性パラメータ：日本接着協会編接着ハンドブック第２版第４６頁に記載あり）、ＳＰ値が離れているほど相溶せず、概ね１．０以上の差の樹脂は相互に親和し難い。また、相互の樹脂の熱溶融温度又は熱軟化温度の離れた樹脂であることも、相互の樹脂が均一化した混和物を形成しない一つの条件であり、概ね１０℃以上の差の樹脂は相互に均一化した混和物を形成し難い。これらの目安は各材料で微妙に異なるので個々の検討が必要である。大事なことは、塗工によりフィルムを作成するときには、一般にフィルム形成接着材を適当な溶剤で溶解、希釈し、適当な粘度の溶液を流延して作成するので、絶縁層は、このフィルム作成時に使用する溶剤やフィルム形成樹脂中の液状成分に溶解せず、即ちフィルム形成接着材溶液に溶解しない樹脂を用いることである。
【００１５】
互いに相溶しない樹脂であれば、適当な溶剤を選択することにより、フィルム形成接着材溶液に溶解しない絶縁層を設けることが可能となる。具体的には熱可塑性ポリウレタン、可溶性ナイロン、エポキシ樹脂、フェノキシ樹脂、ポリエチレン、ポリエステル等が用いられ、これらの中からフィルム形成樹脂溶液に溶解せず、絶縁層の形成が容易な樹脂を選択して用いる。これらの目安は各材料で微妙に異なるので個々の検討が必要である。この絶縁層の厚みは、樹脂のフィルム形成接着材溶液に対する耐溶解性と微小な導電性粒子に対する被覆が充分であるかにより最適値が異なるが、概ね０．０１〜１０μｍが適当である。絶縁層を形成する方法は、樹脂を溶剤に溶解し、溶液状態で導電性粒子表面に塗布した後乾燥する湿式法や、絶縁層を形成する樹脂の粉体と導電性粒子とを高速で衝突させたり、混合してすり合わせたり、融解して付着させる等の乾式法により形成することが出来る。
【００１６】
湿式法は樹脂を適当な溶剤に溶解しなければならないが、絶縁層を所望の厚さに形成することが容易であり、特に、１μｍ以下の薄い絶縁層を容易に形成できる利点がある。乾式法は溶剤に溶解し難い樹脂でも絶縁層を形成できる利点があり、１μｍ以上の厚い絶縁層の形成に適している。これらの絶縁層内の微小な導電性粒子を分散した凝集体とする方法は、例えば湿式法では絶縁層を形成する樹脂溶液中に微小な導電性粒子を分散した状態で導電性粒子表面に塗布したり、乾式法では絶縁層を形成する樹脂の粉体、微小な導電性粒子及び導電性粒子を高速で衝突させたり、混合してすり合わせたり、融解して付着させたりして、絶縁層中に微小な導電性粒子を埋め込む方法等がある。また、あらかじめ湿式法では絶縁層を形成した絶縁被覆導電性粒子と微小な導電性粒子とを乾式法で処理し、絶縁層中に微小な導電性粒子を埋め込む方法も採れる。
【００１７】
粘着材はその粘着性により粒子を散布した後の取扱時やフィルム形成接着材を塗工する際に、導電性粒子が移動しないように保持していればよく、手触り時の粘着感を必要とするものではない。一般的に、導電性粒子表面と粘着材との接触面積が大きければ導電性粒子の保持力が大きくなるので、導電性粒子の散布時に導電性粒子表面の凹凸を埋められるような柔らかい物質であれば粘着材として用いることが可能である。即ち、導電性粒子を散布した後の取扱時やフィルム形成接着材を塗工する際に、導電性粒子と粘着材との付着力により導電性粒子が移動しないように保持する物質を、本発明における粘着材とすることが出来る。
【００１８】
具体的にはＳＢＲ、ポリイソブチレン、ポリブテン、天然ゴム、ネオプレン、ブチルゴム等のゴム類やアクリル樹脂、シリコーン樹脂、弗素樹脂等からなる粘着材を用いることが出来る。また、これらの樹脂や粘着性の無い樹脂にテルペン樹脂やインデン樹脂のような粘着付与材を混合して、粘着性を持たせたものも用いることが出来る。また、これらの樹脂は、フィルム形成接着材との相溶性を小さくするため、架橋による網目構造を持たせてもよい。上記に示した粘着材は基材となるフィルムや板、ロール等の上に塗工して複合構造として用いることで、取扱いが容易となる。一般的にＰＥＴ、ポリエチレン、ポリプロピレン等のフィルムを基材として使用できる。
【００１９】
フィルム形成接着材は、導電性粒子のバインダーとして作用し、フィルム状に成形可能なものである。また、フィルム形成接着材の塗工時に導電性粒子を粘着固定している粘着材を溶解して導電性粒子が移動してしまうのを防ぐために、フィルム形成接着材は粘着材と非相溶なものを選択する。具体的には、溶剤に可溶な各種合成樹脂やエラストマーのほか、ポリエチレン、酢酸ビニル、ポリプロピレン等の熱可塑性樹脂や高耐熱性を有するポリエーテルスルホン、ポリエーテルイミド、ポリイミド等の樹脂やエポキシ樹脂、フェノール樹脂等の熱硬化性樹脂、アクリロイル基を有するウレタンアクリレート、エポキシアクリレート等の光硬化性樹脂を用いることが出来る。互いに非相溶なフィルム形成接着材と粘着材との組み合わせとしては、ポリイソブチレンのようなＳＰ値の小さな粘着材及びポリイミドの硬化前物質であるポリアミック酸のようなＳＰ値の大きな樹脂をフィルム形成接着材として用いることが出来る。
【００２０】
また、シリコーン樹脂や弗素樹脂はこれら以外の多くの樹脂と非相溶であるので、これらの樹脂を粘着材として選択すると、フィルム形成接着材として多くの樹脂を選択出来る。また、本発明の異方導電性樹脂フィルム状接着材を用いて回路間を接続する方法は、回路間を圧接させながら加熱したり光照射することで、回路間の空隙にフィルム状接着材を流動させた後硬化させることで達成できる。このとき、フィルム状接着材の中でも特に熱硬化性樹脂は、回路接続時の熱圧により網状構造を形成して硬化するので耐熱性に優れており、高い接続信頼性が得られることから、フィルム形成接着材の一部として使用されることが望ましい。
【００２１】
樹脂フィルム状接着材の厚みは特に限定するものではないが、前記のように回路間の空隙を満たし、且つ、回路間から流出する接着材量がなるべく少なくすることが望ましいので、接続する回路を密接したときの空隙量から最適なフィルム厚さを決定する。例えば、厚み３５μｍ、電極幅５０μｍ、ピッチ１００μｍの平行な多数の銅電極を有するフレキシブル配線板と同配列の１μｍ以下の厚みの透明電極を持ったガラス基板とを接続する場合には、粒径１０μｍの導電性粒子を配合したフィルムで、概ね１５〜４０μｍのフィルム厚みが適当である。このとき、導電性粒子は回路間に挟持され、回路間に接着材層を作るので、導電性粒子の粒径は勿論のこと変形性や回路への埋め込み量も考慮する必要がある。
【００２２】
マスクは、シルク、ナイロン、ステンレス等の繊維を織った網状のもの、ステンレスやニッケル（Ｎi）の薄板をエッチング等で所望の位置や大きさに透孔を開けた通常メタルマスクと呼ばれるもの、Ｎiや銅（Ｃu）のめっきで作製したメッシュなどが用いられる。これらのマスクは、粘着材や帯電体の上に置いて用いられるが、静電気力により導電性粒子を散布する場合には、マスクの帯電性をマスク素材を選択したりアースをとることにより制御し、マスクの透孔の部分にだけ導電性粒子が配置されるようにすることが望ましい。しかし、マスクの帯電電位がマスク面内で不均一であったりして、マスク上に導電性粒子が付着した場合でもマスクと導電性粒子との静電気による付着性を調節し、マスク上の導電性粒子を樹脂製のブレード等により排除することが出来る。例えば、ナイロン等の非導電性の網でも、篩等に使用される網は一般に帯電防止処理が施されており、マスクに粒子が付着してしまうのを防止するのに有用である。マスクの透孔の大きさは、導電性粒子が通過し得る大きさのものは勿論、導電性粒子が通過しない大きさのものも使用出来る。
【００２３】
必要なことは、マスクの透孔の位置に導電性粒子が配置され、このときに粘着材又は帯電体に導電性粒子の一部が接触し、粘着力又は静電気力により固定されることである。例えば、粘着材面にマスクを載置し、導電性粒子を散布してマスクの透孔部に導電性粒子を固定した後、マスクを取り外さずにフィルム形成接着材を塗布し、異方導電性樹脂フィルム状接着材を得ることが出来る。得られた異方導電性樹脂フィルム状接着材のフィルム形成接着材面からマスクを剥離することでマスクは繰返し使用出来る。このとき、導電性粒子がマスクの透孔を通過する工程を経ないので、マスクの透孔よりも導電性粒子の粒径が大きくてもよい。また、帯電体上にマスクを載置し、静電気力により導電性粒子をマスクの透孔の位置に配置した後に、粘着材面に押圧して転写する場合においても、導電性粒子を配置した後にマスクを取り外す必要はないので、マスクの透孔よりも導電性粒子の粒径が大きくてもよい。
【００２４】
静電気により帯電させる方法は、コロナ帯電装置を用いる方法が一般的で、本発明の目的もこの装置により達成される。この装置は非接触式で物体を帯電させることが出来、帯電量もモニタリングしながら所望の一定値に制御出来る。ほかに、導電性のローラーやブラシに電圧をかけて物体に接触させる接触帯電法等により帯電させることが可能である。帯電は導電性粒子が散布される帯電体、粘着材、マスク等のうち必要な部材になされればよく、導電性粒子との電位差が導電性粒子を移動、吸着するに足る値であれば良い。
【００２５】
このとき、逆に導電性粒子を帯電させる方法も考えられるが、導電性粒子間の静電気力による反発で導電性粒子の飛散が発生したり、個々の導電性粒子で帯電量のばらつきが大きくなる等の問題があり注意を要する。帯電量は通常数百ボルト以上で本発明の目的は達成出来る。帯電体は帯電装置により導電性粒子と異なる電荷に帯電される物質であればよく、一般的にはポリエチレン、ナイロン、ポリエステル等の電気絶縁性の樹脂が広く使用出来る。また、たとえ導電性の金属等でも直接電圧を印加したり、絶縁体で電荷が洩れるのを防いだりすることで、帯電体として使用することが出来る。本発明の異方導電性樹脂フィルム状接着材は、上記した回路の接続材料だけでなく、スイッチ部材、多層回路部材等への応用が可能である。
【００２６】
図１は本発明の異方導電性樹脂フィルム状接着材の製造法における製作順序及び該接着材を用いた微細回路間の接続方法を示すものである。先ず、図１（ａ）に示すように、樹脂フィルム等からなる支持体である基材フィルム３の上に溶液塗工等のコーティングにより粘着材２の層を設け、次に、図１（ｂ）に示すように、この粘着材層の上に導電性粒子を散布し、導電性粒子１を粘着材２の粘着力により保持する。次に図１（ｃ）に示すように、この導電性粒子１の間にフィルム形成接着材１０の溶液を塗工により充填する。このとき、導電性粒子１は粘着材２の上に固定されているのでフィルム形成接着材１０の溶液の中で移動することがなく、塗工時の粒子の凝集が起こらず、均一に面上に配列した状態を保持する。次に乾燥して溶剤を除去し、フィルム形成接着材を得る。
【００２７】
回路間を接続するときには、図１（ｄ）に示すように、一方の回路１１の面に圧接後、フィルム形成接着材１０を粘着材２との界面から剥離し、異方導電性樹脂フィルム状接着材を転写する。このとき、フィルム形成接着材と粘着材とは互いに相溶しないので界面から容易に剥離出来る。１２は電極である。次に、図１（ｅ）に示すように、両回路の位置合わせをした後、加圧又は加熱加圧して両回路１１と１１の間を接着し、電気的導通を得る。加熱加圧するときには、加熱する熱板１４を導電性粒子１が少ないフィルム１０の面から押圧するようにする。１５は定板である。図２の（ａ）は本発明の異方導電性樹脂フィルム状接着材を回路の１１間に挿入して加圧し、電気的接続をした状態を示す。
【００２８】
図２（ｂ）は、従来の製造法で得られた異方導電性樹脂フィルム状接着材１０を回路１１間に挿入して加圧し、電気的接続をした状態を示す。従来法では、フィルム１０の厚さ方向の導電に寄与する導電性粒子１の密度が小さく、回路が微細になると接続が得られない状態になる。また、電極１２間の空隙に流入する導電性粒子１の量が多いので隣接回路間の短絡が発生し易い。この電極間の空隙に流入した導電性粒子は接続に寄与しない導電性粒子であり、本発明の方法によれば、この粒子数を少なく出来るので、コストの低減になる。本発明の製造法では上記の問題点が改良され、微細な回路の電気的接続が得られる。
【００２９】
図３（ａ）は、上記の本発明の異方導電性樹脂フィルム状接着材の製造工程のうち、本発明の請求項１にかかる部分であり、導電性粒子を粘着材層に散布した図である。ここで、導電性粒子１は粘着材２の粘着力により固定されている。図３（ｂ）は、本発明の異方導電性樹脂フィルム状接着材の製造工程のうち、本発明の請求項２にかかる部分であり、導電性粒子１は粘着材２の層上に置かれたマスク４の透孔５の内部で粘着材２と接し固定されている図である。導電性粒子１はブラシ等でマスク４の上を転動し、マスク４の透孔５に入れることが出来る。よって、導電性粒子がフィルム面の所望の配列で存在する異方導電性樹脂フィルム状接着材が得られる。
【００３０】
図３の（ｃ）及び（ｄ）は、本発明の請求項１にかかる部分であり、粘着材面上に導電性粒子の粒径以上の厚さに導電性粒子層を設けた後、導電性粒子層を粘着材面に押圧する工程を示したものである。図３（ｃ）は粘着材２の面上に導電性粒子１の粒径以上の厚さに導電性粒子層を設けたときの図であり、図３（ｄ）は導電性粒子層を粘着材面にゴムロール６で押圧する工程を示したものである。この工程により、導電性粒子と粘着材層との接触面積を大きくし、導電性粒子の固定を均一で確実なものにすると共に、導電性粒子間に挟持され、粘着材層に接していない導電性粒子を押圧し、粘着材層に強制的に接触せることで、異方導電性樹脂フィルム状接着材中の導電性粒子の密度を大きくすることが出来る。
【００３１】
図３の（ｅ）及び（ｆ）は、本発明の請求項３にかかる部分であり、導電性粒子を帯電体上に静電気力により保持し、この帯電体を粘着材面に押圧し、導電性粒子を粘着材面に転写する工程を示したものである。図３（ｅ）は導電性粒子１を帯電体７の上に静電気力により保持したときの図であり、図３（ｆ）はこの帯電体７を粘着材２の面に押圧し、導電性粒子１を粘着材２の面に転写する工程を示したものである。導電性粒子と異なる電荷に帯電させた帯電体を導電性粒子に近接させると、静電気力により帯電体上に導電性粒子が保持される。このとき帯電体上の導電性粒子は各々同一の電荷に帯電するので、導電性粒子は互いに反発しあい、凝集のない単一層状態で帯電体上に配列する。よって、この帯電体上の導電性粒子を粘着材表面に転写することにより、凝集のない単一層状態の導電性粒子の配列を粘着材面に形成することが出来、導電性粒子がフィルム面に均一に分散した異方導電性樹脂フィルム状接着材が得られる。
【００３２】
図３の（ｇ）及び（ｈ）は、本発明の請求項４にかかる部分であり、帯電体上にマスクを設け、マスクの透孔の部分の帯電体上に導電性粒子を静電気力により保持し、この帯電体を粘着材面に押圧し、導電性粒子を粘着材面に転写する工程を示したものである。図３（ｇ）は帯電体７の上にマスク４を設け、マスク４の透孔５の部分の帯電体７上に導電性粒子１を静電気力により保持したときの図であり、図３（ｈ）はこの帯電体７を粘着材２の面に押圧し、導電性粒子１を粘着材２の面に転写する工程を示したものである。マスクは帯電体を粘着材面に押圧する工程の前に取り外す構造としてもよいし、図３（ｇ）に示したようにマスクを付けたまま粘着材面に押圧してもよい。
【００３３】
導電性粒子と異なる電荷に帯電させた帯電体を導電性粒子に近接させると、静電気力により帯電体上に導電性粒子が保持される。このとき、マスク上の導電性粒子は表面に露出したマスクの透孔部分の帯電体上に静電気力により引かれ、マスクの透孔部分に導電性粒子が吸着した配列を形成する。マスクの帯電量を小さくすることで、マスク上に付着する粒子量を少なくすることが可能である。またマスクと帯電体との帯電量の差を大きくすることにより、導電性粒子の吸着力に差を設け、空気の吹き付けによりマスク上に吸着した導電性粒子のみを除去することが可能である。よって、この帯電体上の導電性粒子を粘着材表面に転写することにより、導電性粒子がフィルム面に所望の配列で存在する異方導電性樹脂フィルム状接着材が得られる。
【００３４】
図３（ｉ）は、本発明の請求項５にかかる部分であり、導電性粒子１と粘着材２とを異なる電荷に帯電させ、静電気力により粘着材２の面に導電性粒子１を散布して導電性粒子層を設ける工程を示したものである。この工程は図３（ｅ）の帯電体７を帯電した粘着材層とすることで同様の効果が達成出来、導電性粒子を転写する工程無しに導電性粒子がフィルム面に均一に分散した異方導電性樹脂フィルム状接着材が得られる。また、図３（ｊ）に示すように、図３（ｇ）に示した帯電体７を帯電した粘着材２の層とすることで同様の効果が達成出来、導電性粒子を転写する工程無しに導電性粒子がフィルム面に均一に分散した異方導電性樹脂フィルム状接着材が得られる。
【００３５】
導電性粒子と異なる電荷に帯電させた粘着材層を導電性粒子に近接させると、静電気力により粘着材上に導電性粒子が保持される。このときマスク上の導電性粒子は表面に露出したマスク上の透孔部分の粘着材上に静電気力により引かれ、マスクの透孔部分にのみ導電性粒子が粘着した配列を形成する。マスクの帯電量を小さくすることでマスク上に付着する粒子量を少なくすることが可能であり、マスクと導電性粒子とは粘着していないので、空気の吹き付けやブラシを用いて容易に除去出来る。よって、導電性粒子がフィルム面に所望の配列で存在する異方導電性樹脂フィルム状接着材が得られる。
【００３６】
図３（ｋ）は、本発明の請求項６にかかる部分であり、導電性粒子に代えて繊維状導電体を用い、繊維状導電体８と粘着材２とを異なる電荷に帯電させ、静電気力により粘着材２の面に繊維状導電体８を散布し、導電性粒子層を設ける工程を示したものである。繊維状導電体は、静電気力により帯電体上に散布したときに繊維状導電体同士の静電気力による反発で帯電体面に対し長軸が垂直になった状態で直立する。この繊維状導電体を散布した帯電体を粘着材面に押圧するか、又は図３（ｋ）に示すように帯電体を粘着材２の面とすることにより、粘着材面に繊維状導電体が直立した状態で固定することが出来る。よって、この方法により、フィルムの厚さ方向に繊維状導電体が直立した状態の異方導電性樹脂フィルム状接着材が得られる。このとき、繊維状導電体の径を小さくすることで、導電体の面内の配列密度を高くすることが出来、繊維状導電体の長軸の長さを長くすることでフィルム厚さを厚くし、フィルム強度を向上することが出来る。
【００３７】
図４の（ａ）、（ｂ）及び（ｃ）は、本発明の請求項７にかかる部分であり、導電性粒子又は繊維状導電体が、加熱又は加圧により除去し得る電気絶縁層（絶縁層）であらかじめ表面を被覆した導電性粒子、繊維状導電体又はこれらの凝集体としたときの工程を示したものである。図４（ａ）は絶縁層を形成した導電性粒子（絶縁被覆導電性粒子）９を粘着材２の面に散布した図であり、図４（ｂ）は得られた試料を回路１１の間に挿入したときの図である。１２は電極である。図４（ｃ）は加熱加圧により絶縁層を流動させ、回路１１間の電気的接続がなされている状態を示した図である。絶縁層はフィルム形成接着材溶液に溶解しないので、絶縁層を保持した状態でフィルム形成接着材溶液内に存在し、且つ導電性粒子が粘着材により固定されているので、粒子同士がフィルム形成接着材内で凝集することもなく、フィルム面内に均一に分散した状態になる。よって、導電性粒子同士が接触する密な充填をしても、粒子間の絶縁層により面方向の絶縁性が保持される。相対峙する電極間の電気的接続は加圧又は加熱加圧下で行い、粒子表面の絶縁層を流動除去して得られる。
【００３８】
図４（ｄ）は、本発明の請求項８にかかる部分であり、フィルム形成接着材の１０を回路１１間に挿入した状態を示している。ここで、電極間の空間１３とほぼ等しい体積を持つフィルム厚さのフィルム形成接着材１０を使用している。接続後においては、図２（ａ）に示すように、回路１１間に空隙のない接続体になっている。図４（ｅ）は、本発明の請求項９および１０にかかる部分であり、フィルム１０の厚さ方向で導電性粒子１の濃度が異なっている本発明の異方導電性樹脂フィルム状接着材を用いて接続したとき、導電性粒子１を充填した層は溶融粘度が接着材層よりも大きくなるので流動性が劣り、電極間の空間部１３にはもっぱら接着材のみが充填されるので、隣接回路間の絶縁性が保持され易くなると共に、導電に寄与する導電性粒子１の数が多くなる。また、加熱加圧治具を接着材側から加熱する構造にすると、接着材層が先に溶融して流動状態となるので、電極間の空間部に接着材のみが充填される効果が促進される。
【００３９】
【実施例】
以下、本発明の実施例を説明するが、本発明はこれにより限定を受けない。また、以下に示した実施例及び比較例では、すべて厚さ１０μｍのシリコーン系粘着材（軽剥離タイプ、東芝シリコーン(株)）を厚さ５０μｍのＰＥＴ製基材フィルム上に塗工して用いている。導電性粒子は平均粒径１０μｍのポリスチレン球状粒子の表面に０．２μｍの金の層を設けたプラスチック導電性粒子又は平均繊維長１０μｍ、繊維径約５μｍのニッケル繊維状導電体を用いた。
【００４０】
導電性粒子の表面に絶縁層を設けた絶縁被覆導電性粒子は、絶縁被覆材としてＣＭ４０００（メタノール可溶性ナイロン、東レ(株)）を使用し、メタノールを溶剤としてコートマイザ（フロイント産業(株)）により湿式で厚さ約０．５μｍの絶縁層を着けた。フィルム形成接着材はエピコート１００１／エピコート８２８／ニポール１０３２（ニトリルゴム、日本ゼオン(株)）／ヒタノール２４００（アルキルフェノール、日立化成工業(株)）／キュアゾール２ＰＺ（２−フェニルイミダゾール、四国化成工業(株)）＝５０／２０／２０／１０／２の配合比のフィルム形成接着材トルエン溶液を塗工後、乾燥して得られた熱硬化性エポキシ樹脂を用いた。
【００４１】
製作工程は各実施例に具体的に示すが、粘着材及びフィルム形成接着材の塗工はアプリケーター式塗工機を使用した。熱硬化性エポキシ樹脂の塗工後の乾燥条件は８０℃１０分とした。このとき、熱硬化性エポキシ樹脂の濃度及びアプリケーター式塗工機の塗工ギャップを調整して、フィルム厚さを約２５μｍにした。断面形状を観察すると、粘着材面に固定された１層の導電性粒子層の上に約１５μｍの熱硬化性エポキシ樹脂層がある２層構造のフィルムであった。
【００４２】
得られた異方導電性樹脂フィルム状成形物の評価は、ライン幅５０μｍ、ピッチ１００μｍ、厚さ３５μｍの銅回路を有する全回路幅５０mmのフレキシブル回路板（ＦＰＣ）及びライン幅５０μｍ、ピッチ１００μｍ、厚さ０．１μｍの透明電極回路（ＩＴＯ、Ｉndium Ｔin Ｏxide）を有する全回路幅５０mmのガラス基板配線板を使用し、この配線板同士の回路を対向して位置合わせを行った後、この回路間に得られた異方導電性樹脂フィルム状接着材を挿入し、加圧加熱状態（１０kｇ／cm²、１７０℃）で２０秒間保持して、回路間を試料により接着して評価した。
【００４３】
この接着に使用した装置は、図１（ｅ）及び図４（ｅ）に示すように、室温の定板１５の上に試料を載置し、上から一定温度に加熱された熱板１４で試料を押圧して接着する構造になっており、異方導電性樹脂フィルム状接着材は、導電性粒子１が少ない面を上にして接着材面側から加熱されるように挿入した。接続抵抗及び絶縁抵抗は室温常圧で評価した。測定条件は、一対のＦＰＣ間の接続抵抗を測定電流１ｍＡで測定し、隣接した接続回路間の絶縁抵抗を測定電圧１００Ｖで測定した。この結果は、すべての実施例及び比較例について表１に示した。
【００４４】
実施例１
目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いて、プラスチック導電性粒子をＰＥＴフィルム上のシリコーン系粘着材塗布面に散布した。この粒子散布面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。
【００４５】
実施例２
ＰＥＴフィルム上のシリコーン系粘着材塗布面にマスク（目開き１５μｍの非帯電処理をしたナイロンメッシュ）を密着させ、目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いて、プラスチック導電性粒子をマスク面に散布した。散布後、除電ブラシを用いてマスク上の粒子を転動させ、マスクの透孔内に多くの粒子が入るようにした。次に、粘着材に保持されていない粒子を圧縮エアーの吹き付けにより除去した後、粘着材面からマスクを剥離した。この粒子散布面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。
【００４６】
実施例３
目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いて、プラスチック導電性粒子をＰＥＴフィルム上のシリコーン系粘着材塗布面に散布した。このとき、散布された導電性粒子同士が３個から１０個程度凝集して局所的に層状をなした部分が各所に存在していた。この粒子散布面上に２５μｍのカバー用ＰＥＴフィルムを被せて、ゴムロール間に挿入し、１kｇ／cm²の圧力で押圧した。この後、カバー用ＰＥＴフィルムを剥離し、導電性粒子の散布状態を観察したが、導電性粒子は粘着材面に押圧されて殆ど１層になっていた。この粒子散布面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。
【００４７】
実施例４
目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いて、プラスチック導電性粒子をアルミニウム箔上に散布した。この導電性粒子散布面の上方に、コロナ帯電装置を用いて＋３ｋＶに帯電させたアクリル板を約１cmの距離を置いて導電性粒子散布面に対向するように設置した。このとき、アルミニウム箔上の導電性粒子は静電気力によりアクリル板面に吸着した。また、アクリル板面に吸着した導電性粒子はそれぞれ同電位に帯電するので、導電性粒子間に静電気による反発力が生じ、粒子間の凝集がなく、１層の粒子層を形成していた。この粒子面をシリコーン系粘着材面に押圧して、導電性粒子を粘着材面に転写した。この粒子転写面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。
【００４８】
実施例５
目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いて、プラスチック導電性粒子をアルミニウム箔上に散布した。次に、アクリル板とマスク（目開き１５μｍ、厚み５μｍのＮｉめっき製メッシュ）を張り合わせた板のマスク面側をコロナ帯電装置を用いて＋３ｋＶに帯電させ、導電性粒子散布面の上方に、マスク面が約１cmの距離を置いて導電性粒子散布面に対向するように設置した。このとき、アルミニウム箔上の導電性粒子は静電気力によりマスクの透孔部に吸着した。また、マスク面に吸着した導電性粒子はそれぞれ同電位に帯電するので、導電性粒子間に静電気による反発力が生じ、粒子間の凝集がなく、１層の粒子層を形成していた。この粒子面をシリコーン系粘着材面に押圧して導電性粒子を粘着材面に転写した。この粒子転写面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。
【００４９】
実施例６
プラスチック導電性粒子を目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いてアルミニウム箔上に散布した。次に、ＰＥＴフィルム上のシリコーン系粘着材塗布面に密着させたマスク（ナイロン製、目開き１５μｍ）のマスク面側をコロナ帯電装置を用いて＋３ｋＶに帯電させ、導電性粒子散布面の上方に、マスク面が約１cmの距離を置いて導電性粒子散布面に対向するように設置した。このときアルミニウム箔上の導電性粒子は静電気力によりマスクの孔内に入り、粘着材に粘着固定した。また、粘着材面に固定した導電性粒子はそれぞれ同電位に帯電するので、導電性粒子間に静電気による反発力が生じ、粒子間の凝集がなく、１層の粒子層を形成していた。次に、粘着材面からマスクを剥離した。この粒子散布面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。
【００５０】
実施例７
目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いて、繊維状導電体をアルミニウム箔上に散布した。次に、ＰＥＴフィルム上のシリコーン系粘着材塗布面に密着させたマスク（目開き１５μｍ、厚み５μｍのＮｉめっき製メッシュ）のマスク面側をコロナ帯電装置を用いて＋３ｋＶに帯電させ、繊維状導電体の上方に、マスク面が約１cmの距離を置いて繊維状導電体散布面に対向するように設置した。このとき、アルミニウム箔上の繊維状導電体は静電気力によりマスクの孔内に入り、粘着材に粘着固定した。このとき繊維状導電体は粘着材面にほぼ直立し、粘着材中に数μｍ埋まった状態で固定されていた。また、粘着材面に固定した繊維状導電体はそれぞれ同電位に帯電するので、繊維状導電体間に静電気による反発力が生じ、繊維状導電体間の凝集がなく１層の導電体層を形成していた。次に、粘着材面からマスクを剥離した。この粒子散布面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。このフィルムの厚みは約２５μｍであり、粘着材面に固定された１層の繊維状導電体層の上に約１５μｍの熱硬化性エポキシ樹脂層がある２層構造のフィルムであった。
【００５１】
実施例８
目開き２０μｍの篩を通して粉体を散布する乾式の粒子散布装置を用いて、絶縁被覆導電性粒子をＰＥＴフィルム上のシリコーン系粘着材塗布面に散布した。この粒子散布面に熱硬化性エポキシ樹脂溶液を塗工後、乾燥した。
比較例
図５に示すように、フィルム形成接着材１０の熱硬化性エポキシ樹脂の溶液中にプラスチック導電性粒子１を配合量３０体積％分散し、アプリケータ塗工装置を用いてテフロンの基材フィルム３上に流延塗布後、乾燥した。このフィルムは導電性粒子の凝集体が多く存在して表面の凹凸が大きかったが、平均的なフィルム厚さは約２５μｍであった。
【００５２】
【表１】

注）Ａは接続抵抗不良（１０Ω以上）の発生率（％）
Ｂは絶縁抵抗不良（１０⁶Ω以下）の発生率（％）
【００５３】
【発明の効果】
本発明によれば、異方導電性樹脂フィルム状接着材内の導電性粒子を単一層構造とし、フィルム内の導電性粒子の充填量を多く出来るので、接着材の単位面積当りの導電点を多くすることが出来、従来に比べて分解性能に優れた異方導電性樹脂フィルム状接着材が得られ、高精細な電極間の電気的接続が可能になる。
【図面の簡単な説明】
【図１】本発明の異方導電性樹脂フィルム状接着材の製造法における製作順序を説明する断面図である。
【図２】異方導電性樹脂フィルム状接着材により回路を接続したときの断面図であり、（ａ）は本発明で得られた接着材を用いた場合、（ｂ）は従来の製造法で得られた接着材を用いた場合である。
【図３】本発明の異方導電性樹脂フィルム状接着材の製造法における各種の製作例を説明する断面図である。
【図４】本発明の異方導電性樹脂フィルム状接着材の製造法における各種の製作例を説明する断面図である。
【図５】従来の異方導電性樹脂フィルム状接着材の製造法を説明する断面図である。
【符号の説明】
１…導電性粒子、２…粘着材、３…基材フィルム、４…マスク、５…透孔、６…ゴムロール、７…帯電体、８…繊維状導電体、９…絶縁被覆導電性粒子、１０…フィルム形成接着材、１１…回路、１２…電極、１３…電極間の空間、１４…熱板、１５…定板[0001]
[Industrial application fields]
The present invention relates to a method for producing an anisotropic conductive resin film adhesive having conductivity only in the thickness direction through conductive particles dispersed in the resin film adhesive, and an adhesive obtained by the production method The present invention relates to a method for connecting between microcircuits using the.
[0002]
[Prior art]
As electronic components become smaller and thinner, circuits used for these components are becoming higher in density and higher in definition. Since connection of these microcircuits is difficult with conventional solders, rubber connectors, etc., connection members made of anisotropically conductive adhesives and film-like materials have recently been frequently used. In this method, an electrical connection member layer made of an insulating resin containing a predetermined amount of a conductive material is provided between opposing circuits, and electrical pressure between upper and lower circuits is provided by applying pressure or heating and pressing means. Simultaneously with the connection, insulation is provided between adjacent circuits. In addition, a material that uses the insulating resin as an adhesive and that bonds and fixes the circuits at the same time as the electrical connection between the circuits facing each other is also used. As prior art documents regarding such an anisotropic conductive resin film adhesive having conductivity only in the thickness direction, for example, as disclosed in JP-A-51-21192, conductive particles The mixture in which the non-conductive bases are kept in contact with each other is formed into a sheet shape having a thickness substantially equal to the size of the conductive particles, and the conductive property is made to pass through the conductive particles only in the thickness direction of the sheet shape. Some have a structure.
[0003]
These resin film adhesives are formed by casting a uniform dispersion of conductive particles in a liquid resin at a constant thickness using a bar coater, etc., and then drying or curing the adhesive. Is what you get. In addition, it is assumed that the concentration of conductive particles is different in the thickness direction of the film. , Transparent After the conductive particles are put into the film having the holes, the film and the conductive particles are bonded and fixed, or the conductive properties as disclosed in JP-A-2-117980 and JP-A-5-67480. There is also a method of embedding the conductive particles in a film-like adhesive. In this anisotropically conductive resin film adhesive that has conductivity only in the thickness direction, to increase the number of conductive points per unit area of the film and increase the resolution, the blending amount of conductive particles in the film Need to increase.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional method of casting a uniform mixture of a liquid resin and conductive particles to form a film, if an attempt is made to increase the amount of conductive particles in order to cope with a high-definition electrode, the conductive Since the viscosity of the liquid resin in which the conductive particles are dispersed is increased and the fluidity is impaired, it becomes difficult to cast at a constant thickness by a bar coater or the like, and it is necessary to reduce the blending amount of the conductive particles. Absent. Furthermore, in such a film in which conductive particles are uniformly dispersed in the film, the conductive particles are not sandwiched between the connected circuits as the amount of the conductive particles is increased in order to cope with a high-definition circuit. There is a problem in that the amount of conductive particles between adjacent circuits that do not contribute increases and the manufacturing cost increases.
[0005]
In addition, in the method of adhering and fixing the film and the conductive particles after putting the conductive particles into the film provided with the through holes, providing a large number of minute holes in the film should be carried out in terms of productivity and cost. Is difficult. Furthermore, in the method of embedding the conductive particles in the film-like adhesive, the adhesive cannot be sufficiently wetted on the surface of the conductive particles unless the viscosity of the adhesive is sufficiently low as a liquid. Adhesiveness with the adhesive is inferior, and the conductive particles easily fall off. When a liquid film-like resin is used, it is inevitable that the adhesive adheres to the support in the process of transferring the conductive particles held on the support to the liquid adhesive surface, making it difficult to form a film. Become.
[0006]
In addition, when the filling amount of the conductive particles is increased, it becomes difficult to fill the gaps between the conductive particles with the adhesive without excess or deficiency. The relationship with the thickness of the film adhesive must be strictly specified. If the thickness of the film-like adhesive is thick, the adhesion of the adhesive to the above-mentioned support is inevitable, and if it is thin, the strength as a film cannot be obtained or the particles fall off. The present invention has been made in view of such a situation, and an object of the present invention is to provide a novel method for manufacturing an anisotropic conductive resin film-like adhesive that can be electrically connected even with a fine electrode.
[0007]
[Means for Solving the Problems]
The present invention is a method for producing an anisotropic conductive resin film adhesive having conductivity only in the thickness direction through conductive particles uniformly dispersed in the plane direction, After providing a conductive particle layer with a thickness equal to or larger than the particle size of the conductive particles on the adhesive material surface, the conductive particle layer is pressed against the adhesive material surface, An anisotropic conductive resin film in which conductive particles are adhesively fixed to the adhesive material surface, and a film-forming adhesive that is incompatible with the adhesive material is filled between the conductive particles, and then the adhesive material is peeled off from the film-forming adhesive. The present invention relates to a method for manufacturing a shaped adhesive, and a method for connecting microcircuits using an adhesive obtained by the manufacturing method. That is, the present invention provides a film-forming adhesive solution that is incompatible with the adhesive material after the conductive particles are dispersed on the adhesive material surface and fixed in a state where the conductive particles are arranged in the surface direction. It is a manufacturing method of the resin film adhesive which has the process of apply | coating and filling between electroconductive particle | grains which has electroconductivity only in the thickness direction of a film.
[0008]
In the present invention, a film or a net having a through hole on the adhesive material surface (hereinafter referred to as a mask) is placed as a jig, and conductive particles are dispersed (claim 2). Conductive particles can be attached only to the adhesive material surface in the hole, and conductive particles can be placed at desired positions within the surface of the film, and conductive particles can be disposed only at the electrode positions of the circuit within the surface. It becomes possible to arrange. In addition, after the conductive particles are sprayed on the adhesive material surface, the conductive particles are pressed against the adhesive material surface using a rubber roll or the like. 1 ), The arrangement density of the conductive particles in the surface direction can be improved.
[0009]
As a method of fixing the conductive particles of the present invention to the adhesive material surface, the conductive particles are held on a roll-like charged body by static electricity, and then the charged body is pressed against the adhesive material surface to adhere the conductive particles to the adhesive material surface. Transferring to the surface of the material (claim) 3 ) Makes it possible to continuously arrange a certain amount of conductive particles. At this time, a mask is placed on the charged body, and conductive particles are dispersed (claims) 4 ), The conductive particles can be attached only to the surface of the charged body in the through hole, and the conductive particles can be arranged at a desired position in the plane of the film. Further, the conductive particles and the adhesive material surface are charged to different charges, and the conductive particles are adsorbed on the adhesive material surface and then fixed. 5 However, a certain amount of conductive particles can be continuously arranged. Also in this case, by placing a mask on the adhesive material and spraying the conductive particles, the conductive particles can be attached only to the adhesive material surface in the through hole, and the desired position in the plane of the film. It becomes possible to arrange the conductive particles on the surface.
[0010]
In the method of fixing the conductive particles to the adhesive material surface by electrostatic force, the conductive particles are made into fibrous conductors (claims) 6 ) Makes it possible to produce an anisotropic conductive resin film-like adhesive in which the long axes of fibers are arranged perpendicular to the film surface, and it is possible to improve conductivity by filling the conductor with high density. The surface of the conductive particles or the fibrous conductor is previously coated with an electrically insulating layer such as a thermoplastic resin that can be removed by heating or pressurization (claim). 7 ), It is possible to maintain the insulation in the surface direction even when the film is closely packed in the surface direction of the film. Further, the electrodes are aligned so as to have a volume approximately equal to the volume of the space formed when the two circuits with the thickness of the film-forming adhesive are relatively in close contact with each other (claims). 8 ) Makes it possible to create a connection body with no gaps in the connection part and little protrusion of the adhesive, preventing deterioration of connection reliability due to the intrusion of humidity and short circuit between adjacent circuits due to the flow of conductive particles during connection. I can do it.
[0011]
Moreover, it is set as the film of the 2 layer structure which thickened the coating thickness of the adhesive material and provided the adhesive material layer on the layer of electroconductive particle. 9 ) Is possible. In this film, the adhesive layer without conductive particles has a lower melt viscosity when connected than the layer filled with conductive particles, so the adhesive layer easily flows into the recesses between the electrodes, and the conductive particles flow into the film. It is hard to do. Therefore, the short circuit between adjacent electrodes can be extremely reduced, and the number of particles contributing to conduction can be increased. Furthermore, when this is connected, it is heated and pressed from the adhesive layer side. 10 ), Since the adhesive layer side melts first and flows into the recesses between the electrodes, the above-described effects can be improved.
[0012]
The type of conductive particles used in the present invention is not particularly limited, and metal particles or particles having a metal plating layer formed on the surface of particles such as glass, ceramic, and plastic may be used alone or in combination. I can do it. It is also possible to use those in which each individual conductive particle is composed of an aggregate of conductive particles having a small particle diameter. The particle size is selected according to the fineness of the circuit to be connected, but the particle size of each particle needs to be as uniform as possible. The shape is preferably a spherical shape in order to make the particle size uniform for the connection of the fine electrodes. Generally, when connecting very fine electrodes, use particles with a metal plating layer on the surface of spherical plastic particles. When using metal particles for heat resistance, etc. It is preferable to use particles produced by an electrode atomizing method. However, even amorphous particles such as metal powders produced by the water atomization method can be used as conductive particles by aligning the particle size by classification.
[0013]
Further, the fibrous conductor used in the present invention has a shape having a long axis and is not affected by the manufacturing method. That is, it can be said that the fibrous conductor has a major axis among the conductive particles. The type of the fibrous conductor is not particularly limited, and commercially available short metal fibers, those obtained by metal plating on the glass fiber surface, carbon fibers, or the like can be used. The diameter and length of the fiber are selected according to the fineness of the electrode to be connected, but it is better for the electrode to be finer if the fiber length is uniform and the fiber diameter is small and uniform. I can do it. In addition, when a mask that controls the fixing position of the conductive particles is not used, in order to ensure the insulation in the surface direction, the amount of the conductive particles and the fibrous conductor to be applied to the adhesive material surface must be appropriate. Don't be. As the conductive particles and the fibrous conductors are in contact with each other, the insulation in the surface direction is impaired. Therefore, obtaining a high-density conductive point can be achieved by providing an electrical insulating layer (insulating layer) on the surface of each conductive particle or fibrous conductor.
[0014]
The insulating layer includes a resin that is incompatible with the film-forming resin, and can have a single layer structure or a multilayer structure. Here, the term “not compatible” means that the resins do not have an affinity and do not form a uniform admixture. As a general measure of compatibility, there is an SP value (solubility parameter: Japan Adhesion). (As described in Association Handbook, Second Edition, page 46), the more the SP value is farther, the less compatible, and resins with a difference of approximately 1.0 or more are hardly compatible with each other. In addition, it is also possible that the resins are separated from each other by heat melting temperature or heat softening temperature. Mixed This is one condition that does not form a hydrate, and resins having a difference of approximately 10 ° C. or more are unlikely to form a uniform mixture. These guidelines are slightly different for each material, so individual considerations are necessary. Importantly, when creating a film by coating, generally the film-forming adhesive is dissolved and diluted with an appropriate solvent, and a solution with an appropriate viscosity is cast. The use of a resin that does not dissolve in the liquid components in the solvent or film-forming resin sometimes used, that is, does not dissolve in the film-forming adhesive solution.
[0015]
If the resins are incompatible with each other, an insulating layer that does not dissolve in the film-forming adhesive solution can be provided by selecting an appropriate solvent. Specifically, thermoplastic polyurethane, soluble nylon, epoxy resin, phenoxy resin, polyethylene, polyester, etc. are used, and a resin that does not dissolve in the film-forming resin solution and that can easily form an insulating layer is selected from these. Use. These guidelines are slightly different for each material, so individual considerations are necessary. The optimum thickness of the insulating layer varies depending on whether the resin is resistant to dissolution in the film-forming adhesive solution and whether the coating on the fine conductive particles is sufficient, but is generally about 0.01 to 10 μm. The insulating layer can be formed by dissolving the resin in a solvent, applying the solution on the surface of the conductive particles and then drying, or colliding the resin powder forming the insulating layer with the conductive particles at high speed. Or can be formed by a dry method such as mixing, rubbing, melting and adhering.
[0016]
In the wet method, the resin must be dissolved in a suitable solvent, but it is easy to form the insulating layer to a desired thickness, and in particular, there is an advantage that a thin insulating layer of 1 μm or less can be easily formed. The dry method has an advantage that an insulating layer can be formed even with a resin that is difficult to dissolve in a solvent, and is suitable for forming a thick insulating layer of 1 μm or more. For example, in the wet method, the fine conductive particles are dispersed in the resin solution forming the insulating layer and applied to the surface of the conductive particles. In the dry method, the resin powder, fine conductive particles and conductive particles that form the insulating layer are collided at high speed, mixed and rubbed together, or melted and adhered to each other in the insulating layer. There is a method of embedding minute conductive particles. In addition, in the wet method, a method in which the insulating coated conductive particles on which the insulating layer has been formed and the minute conductive particles are processed by a dry method and the minute conductive particles are embedded in the insulating layer can be employed.
[0017]
Adhesives need only be held so that the conductive particles do not move during handling after coating the particles or when applying film-forming adhesives due to their stickiness. Not what you want. In general, the larger the contact area between the surface of the conductive particles and the adhesive, the greater the holding power of the conductive particles. Therefore, it should be a soft substance that can fill the irregularities on the surface of the conductive particles when spraying the conductive particles. It can be used as an adhesive material. That is, a substance that holds the conductive particles so that they do not move due to the adhesive force between the conductive particles and the adhesive material when handling after coating the conductive particles or when applying a film-forming adhesive. It can be used as an adhesive material.
[0018]
Specifically, rubbers such as SBR, polyisobutylene, polybutene, natural rubber, neoprene, and butyl rubber, or an adhesive material made of acrylic resin, silicone resin, fluorine resin, or the like can be used. In addition, it is also possible to use those obtained by mixing these resins or non-sticky resins with a tackifier such as a terpene resin or an indene resin to give them stickiness. These resins may have a network structure by crosslinking in order to reduce the compatibility with the film-forming adhesive. The above-mentioned pressure-sensitive adhesive material can be easily handled by coating it on a base film, plate, roll or the like and using it as a composite structure. Generally, a film such as PET, polyethylene, or polypropylene can be used as a base material.
[0019]
The film-forming adhesive acts as a binder for conductive particles and can be formed into a film. In addition, the conductive particles are moved by dissolving the adhesive that sticks and fixes the conductive particles during the application of the film-forming adhesive. of In order to prevent this, the film-forming adhesive is selected to be incompatible with the adhesive. Specifically, in addition to various synthetic resins and elastomers soluble in solvents, thermoplastic resins such as polyethylene, vinyl acetate, and polypropylene, and resins and epoxy resins such as polyethersulfone, polyetherimide, and polyimide having high heat resistance A thermosetting resin such as a phenol resin, a photocurable resin such as a urethane acrylate having an acryloyl group, and an epoxy acrylate can be used. As a combination of a film-forming adhesive material and an adhesive material that are incompatible with each other, an adhesive material with a small SP value such as polyisobutylene and a resin with a large SP value such as polyamic acid that is a polyimide pre-curing material are formed. It can be used as an adhesive.
[0020]
Further, since silicone resins and fluorine resins are incompatible with many other resins, when these resins are selected as adhesive materials, many resins can be selected as film-forming adhesives. In addition, the method of connecting between circuits using the anisotropic conductive resin film adhesive of the present invention is that the film adhesive is applied to the gap between circuits by heating or irradiating light while pressing the circuits. This can be achieved by flowing and then curing. At this time, among the film adhesives, the thermosetting resin is particularly excellent in heat resistance because it forms and forms a network structure by the heat pressure at the time of circuit connection, and high connection reliability is obtained. It is desirable to be used as part of a forming adhesive.
[0021]
The thickness of the resin film adhesive is not particularly limited, but it is desirable to fill the gap between the circuits as described above and to reduce the amount of the adhesive flowing out between the circuits as much as possible. The optimum film thickness is determined from the amount of voids in close contact. For example, when connecting a flexible wiring board having a large number of parallel copper electrodes having a thickness of 35 μm, an electrode width of 50 μm, and a pitch of 100 μm to a glass substrate having a transparent electrode having a thickness of 1 μm or less in the same arrangement, a particle diameter of 10 μm In general, a film thickness of 15 to 40 μm is appropriate. At this time, since the conductive particles are sandwiched between the circuits and an adhesive layer is formed between the circuits, it is necessary to consider not only the particle size of the conductive particles but also the deformability and the amount embedded in the circuit.
[0022]
The mask is a net-like material woven with fibers of silk, nylon, stainless steel, etc., or a so-called metal mask having a through hole in a desired position or size by etching a thin plate of stainless steel or nickel (Ni), Ni. Or a mesh produced by copper (Cu) plating. These masks are used by placing them on an adhesive or a charged body. When conductive particles are sprayed by electrostatic force, the mask chargeability is controlled by selecting the mask material or grounding. It is desirable that the conductive particles are disposed only in the through-hole portions of the mask. However, even if the charge potential of the mask is non-uniform in the mask surface and conductive particles adhere to the mask, the adhesion between the mask and the conductive particles due to static electricity is adjusted, and the conductivity on the mask The particles can be removed by a resin blade or the like. For example, even for non-conductive nets such as nylon, nets used for sieves and the like are generally subjected to antistatic treatment, which is useful for preventing particles from adhering to the mask. As the size of the through-hole of the mask, not only the size that allows the conductive particles to pass through but also the size that does not allow the conductive particles to pass through can be used.
[0023]
What is necessary is that the conductive particles are arranged at the positions of the through holes of the mask, and at this time, a part of the conductive particles comes into contact with the adhesive material or the charged body and is fixed by the adhesive force or the electrostatic force. . For example, after placing a mask on the adhesive material surface, spraying conductive particles to fix the conductive particles in the through-holes of the mask, and then applying a film-forming adhesive without removing the mask, anisotropic conductivity A resin film adhesive can be obtained. The mask can be repeatedly used by peeling the mask from the film-forming adhesive surface of the obtained anisotropic conductive resin film adhesive. At this time, since the conductive particles do not pass through the through holes of the mask, the particle diameter of the conductive particles may be larger than the through holes of the mask. Also, after placing the conductive particles after placing the mask on the charged body and placing the conductive particles at the positions of the through holes of the mask by electrostatic force, Since it is not necessary to remove the mask, the particle size of the conductive particles may be larger than the through holes of the mask.
[0024]
As a method of charging by static electricity, a method using a corona charging device is generally used, and the object of the present invention is also achieved by this device. This device can charge an object in a non-contact manner, and can be controlled to a desired constant value while monitoring the charge amount. In addition, charging can be performed by a contact charging method in which a voltage is applied to a conductive roller or brush to contact an object. Charging may be performed on a necessary member of a charged body, an adhesive material, a mask, or the like on which conductive particles are dispersed, and the potential difference with the conductive particles may be a value sufficient to move and adsorb the conductive particles. .
[0025]
At this time, conversely, a method of charging the conductive particles is also conceivable, but scattering of the conductive particles occurs due to repulsion due to electrostatic force between the conductive particles, or variation in charge amount among individual conductive particles increases. There are problems such as, and attention is necessary. The object of the present invention can be achieved when the charge amount is usually several hundred volts or more. The charged body may be any substance that is charged to a different charge from the conductive particles by the charging device, and generally an electrically insulating resin such as polyethylene, nylon, or polyester can be widely used. In addition, even a conductive metal or the like can be used as a charged body by directly applying a voltage or preventing leakage of charges by an insulator. The anisotropic conductive resin film adhesive of the present invention can be applied not only to the circuit connection material described above but also to a switch member, a multilayer circuit member, and the like.
[0026]
FIG. 1 shows a manufacturing sequence in a method for manufacturing an anisotropic conductive resin film adhesive according to the present invention and a method for connecting microcircuits using the adhesive. First, as shown in FIG. 1A, a layer of an adhesive material 2 is provided on a base film 3 which is a support made of a resin film or the like by coating such as solution coating, and then FIG. ), Conductive particles are dispersed on the adhesive layer, and the conductive particles 1 are held by the adhesive force of the adhesive 2. Next, as shown in FIG. 1C, a solution of the film-forming adhesive 10 is filled between the conductive particles 1 by coating. At this time, since the conductive particles 1 are fixed on the adhesive material 2, the conductive particles 1 do not move in the solution of the film-forming adhesive 10, and the particles do not aggregate at the time of coating. Keep the state arranged in. Next, the solvent is removed by drying to obtain a film-forming adhesive.
[0027]
When connecting the circuits, as shown in FIG. 1 (d), after pressure-contacting the surface of one circuit 11, the film-forming adhesive 10 is peeled off from the interface with the adhesive material 2, and the anisotropic conductive resin film-like is formed. Transfer the adhesive. At this time, since the film-forming adhesive and the pressure-sensitive adhesive are not compatible with each other, they can be easily peeled off from the interface. Reference numeral 12 denotes an electrode. Next, as shown in FIG. 1E, after both circuits are aligned, pressurization or heating and pressurization is performed to bond the

circuits

11 and 11 to obtain electrical continuity. When heating and pressurizing, the heating plate 14 to be heated is pressed from the surface of the film 10 with few conductive particles 1. Reference numeral 15 denotes a plate. FIG. 2A shows a state where the anisotropic conductive resin film adhesive of the present invention is inserted between the circuits 11 and pressed to be electrically connected.
[0028]
FIG. 2B shows a state where the anisotropic conductive resin film adhesive 10 obtained by the conventional manufacturing method is inserted between the circuits 11 and pressed to be electrically connected. In the conventional method, the density of the conductive particles 1 contributing to the conduction in the thickness direction of the film 10 is small, and when the circuit becomes fine, connection cannot be obtained. Moreover, since there is much quantity of the electroconductive particle 1 which flows in into the space | gap between the electrodes 12, it is easy to generate | occur | produce a short circuit between adjacent circuits. The conductive particles that have flowed into the gap between the electrodes are conductive particles that do not contribute to the connection. According to the method of the present invention, the number of particles can be reduced, thereby reducing the cost. In the manufacturing method of the present invention, the above-mentioned problems are improved and a fine circuit electrical connection can be obtained.
[0029]
Fig.3 (a) is a part concerning Claim 1 of this invention among the manufacturing processes of said anisotropically conductive resin film adhesive of this invention, The figure which spread | distributed the electroconductive particle to the adhesive material layer. It is. Here, the conductive particles 1 are fixed by the adhesive force of the adhesive material 2. FIG. 3B is a part according to claim 2 of the manufacturing process of the anisotropic conductive resin film adhesive of the present invention, and the conductive particles 1 are placed on the adhesive material 2 layer. It is the figure which is in contact with the adhesive material 2 and fixed inside the through-hole 5 of the mask 4 put. The conductive particles 1 roll on the mask 4 with a brush or the like and can enter the through holes 5 of the mask 4. Therefore, an anisotropic conductive resin film adhesive having conductive particles in a desired arrangement on the film surface can be obtained.
[0030]
3 (c) and 3 (d) show the claims of the present invention. 1 This is a portion related to the above, and shows a step of pressing the conductive particle layer against the pressure-sensitive adhesive surface after providing the conductive particle layer on the pressure-sensitive adhesive surface with a thickness equal to or larger than the particle size of the conductive particles. FIG. 3C is a view when a conductive particle layer is provided on the surface of the adhesive material 2 with a thickness equal to or larger than the particle diameter of the conductive particles 1, and FIG. The process of pressing the material surface with the rubber roll 6 is shown. By this process, the contact area between the conductive particles and the adhesive layer is increased, the fixing of the conductive particles is made uniform and reliable, and the conductive material that is sandwiched between the conductive particles and is not in contact with the adhesive layer. The density of the conductive particles in the anisotropic conductive resin film adhesive can be increased by pressing the conductive particles and forcibly contacting the adhesive material layer.
[0031]
3 (e) and 3 (f) show the claims of the present invention. 3 FIG. 4 shows a process in which conductive particles are held on a charged body by electrostatic force, the charged body is pressed against an adhesive material surface, and the conductive particles are transferred to the adhesive material surface. FIG. 3E is a view when the conductive particles 1 are held on the charged body 7 by electrostatic force, and FIG. 3F is a view showing that the charged body 7 is pressed against the surface of the adhesive material 2 to be conductive. The process of transferring the particles 1 onto the surface of the adhesive material 2 is shown. When a charged body charged to a different charge from the conductive particles is brought close to the conductive particles, the conductive particles are held on the charged body by electrostatic force. At this time, since the conductive particles on the charged body are each charged with the same charge, the conductive particles repel each other and are arranged on the charged body in a single layer state without aggregation. Therefore, by transferring the conductive particles on the charged body to the surface of the adhesive material, it is possible to form an array of conductive particles in a single layer state without aggregation on the surface of the adhesive material. A uniformly dispersed anisotropic conductive resin film adhesive is obtained.
[0032]
(G) and (h) in FIG. 3 are claims of the present invention. 4 A mask is provided on the charged body, the conductive particles are held on the charged body in the through-hole portion of the mask by electrostatic force, the charged body is pressed against the adhesive material surface, and the conductive particles are The process of transferring to the adhesive material surface is shown. FIG. 3G is a view when the mask 4 is provided on the charged body 7 and the conductive particles 1 are held by the electrostatic force on the charged body 7 in the portion of the through hole 5 of the mask 4. h) shows a step of pressing the charged body 7 against the surface of the adhesive material 2 and transferring the conductive particles 1 onto the surface of the adhesive material 2. The mask may be structured to be removed before the step of pressing the charged body against the adhesive material surface, or may be pressed against the adhesive material surface while the mask is attached as shown in FIG.
[0033]
When a charged body charged to a different charge from the conductive particles is brought close to the conductive particles, the conductive particles are held on the charged body by electrostatic force. At this time, the conductive particles on the mask are attracted by the electrostatic force onto the charged body of the through hole portion of the mask exposed on the surface, thereby forming an array in which the conductive particles are adsorbed on the through hole portion of the mask. By reducing the charge amount of the mask, the amount of particles adhering to the mask can be reduced. Further, by increasing the difference in charge amount between the mask and the charged body, it is possible to provide a difference in the adsorption force of the conductive particles, and to remove only the conductive particles adsorbed on the mask by blowing air. Therefore, by transferring the conductive particles on the charged body to the surface of the adhesive material, an anisotropic conductive resin film adhesive in which the conductive particles exist in a desired arrangement on the film surface can be obtained.
[0034]
FIG. 3 (i) shows the claims of the present invention. 5 This shows the process of charging the conductive particles 1 and the adhesive material 2 to different charges and spreading the conductive particles 1 on the surface of the adhesive material 2 by electrostatic force to provide a conductive particle layer. It is. In this step, the same effect can be achieved by using the charged adhesive layer 7 in FIG. 3E as a charged adhesive layer, and the conductive particles are uniformly dispersed on the film surface without transferring the conductive particles. A directionally conductive resin film adhesive is obtained. Further, as shown in FIG. 3 (j), the same effect can be achieved by forming the charged body 7 shown in FIG. 3 (g) as a layer of the charged adhesive material 2, and there is no step of transferring conductive particles. An anisotropic conductive resin film adhesive in which conductive particles are uniformly dispersed on the film surface is obtained.
[0035]
When the pressure-sensitive adhesive layer charged to a different charge from the conductive particles is brought close to the conductive particles, the conductive particles are held on the pressure-sensitive adhesive material by electrostatic force. At this time, the conductive particles on the mask are attracted by the electrostatic force onto the adhesive material of the through-hole portion on the mask exposed on the surface, thereby forming an array in which the conductive particles adhere only to the through-hole portion of the mask. By reducing the amount of charge on the mask, the amount of particles adhering to the mask can be reduced, and the mask and conductive particles are not sticking together, so they can be easily removed by blowing air or using a brush. . Therefore, an anisotropic conductive resin film adhesive having conductive particles in a desired arrangement on the film surface is obtained.
[0036]
FIG. 3 (k) shows the claims of the present invention. 6 In this case, a fibrous conductor is used in place of the conductive particles, the fibrous conductor 8 and the adhesive material 2 are charged to different charges, and the fibrous conductor 8 is formed on the surface of the adhesive material 2 by electrostatic force. The process of spraying and providing a conductive particle layer is shown. The fibrous conductor stands upright with its major axis perpendicular to the surface of the charged body due to repulsion caused by the electrostatic force between the fibrous conductors when dispersed on the charged body by electrostatic force. The charged body on which the fibrous conductor is dispersed is pressed against the surface of the adhesive material, or the charged body is used as the surface of the adhesive material 2 as shown in FIG. Can be fixed upright. Therefore, by this method, an anisotropic conductive resin film adhesive having a fibrous conductor upright in the thickness direction of the film is obtained. At this time, by reducing the diameter of the fibrous conductor, the arrangement density in the plane of the conductor can be increased, and by increasing the length of the major axis of the fibrous conductor, the film thickness is increased. In addition, the film strength can be improved.
[0037]
4 (a), (b) and (c) are claimed in the present invention. 7 Conductive particles, fibrous conductors, or aggregates thereof, the surfaces of which are covered with an electrical insulating layer (insulating layer) that can be removed by heating or pressurization. This shows the process. 4A is a view in which conductive particles (insulating coated conductive particles) 9 having an insulating layer formed thereon are scattered on the surface of the adhesive material 2, and FIG. It is a figure when it inserts in. Reference numeral 12 denotes an electrode. FIG. 4C is a diagram showing a state in which the insulating layer is caused to flow by heat and pressure and electrical connection between the circuits 11 is made. Since the insulating layer does not dissolve in the film-forming adhesive solution, since the insulating layer is held in the film-forming adhesive solution and the conductive particles are fixed by the adhesive material, the particles are bonded to each other by the film-forming adhesive. It does not agglomerate in the material and is uniformly dispersed in the film surface. Therefore, even in the case of close packing where the conductive particles come into contact with each other, the insulation in the surface direction is maintained by the insulating layer between the particles. Electrical connection between the opposing electrodes is performed under pressure or heat and pressure, and the insulating layer on the particle surface is fluidized and removed.
[0038]
FIG. 4 (d) shows the claims of the present invention. 8 It is a part concerning, and the state which inserted 10 of the film formation adhesive between the circuits 11 is shown. Here, a film-forming adhesive 10 having a film thickness having a volume substantially equal to the space 13 between the electrodes is used. After the connection, as shown in FIG. 2A, the connection body has no gap between the circuits 11. FIG. 4 (e) shows the claims of the present invention. 9 and 10 A layer filled with the conductive particles 1 when connected using the anisotropic conductive resin film adhesive of the present invention in which the concentration of the conductive particles 1 is different in the thickness direction of the film 10. Since the melt viscosity is larger than that of the adhesive layer, the fluidity is inferior, and since the space 13 between the electrodes is filled only with the adhesive, it is easy to maintain the insulation between the adjacent circuits, and it is conductive. The number of conductive particles 1 that contribute is increased. In addition, when the heating / pressurizing jig is heated from the adhesive side, the adhesive layer is melted first to be in a fluid state, thereby promoting the effect of filling only the adhesive in the space between the electrodes. The
[0039]
【Example】
Examples of the present invention will be described below, but the present invention is not limited thereby. In the examples and comparative examples shown below, a silicone adhesive material (light release type, Toshiba Silicone Co., Ltd.) having a thickness of 10 μm is applied on a PET substrate film having a thickness of 50 μm. ing. The conductive particles used were plastic conductive particles in which a 0.2 μm gold layer was provided on the surface of polystyrene spherical particles having an average particle diameter of 10 μm, or nickel fibrous conductors having an average fiber length of 10 μm and a fiber diameter of about 5 μm.
[0040]
Insulating coated conductive particles provided with an insulating layer on the surface of the conductive particles use CM4000 (methanol-soluble nylon, Toray Industries, Inc.) as an insulating coating material, and coatmizer (Freund Sangyo Co., Ltd.) using methanol as a solvent. As a result, an insulating layer having a thickness of about 0.5 μm was applied by a wet method. The film-forming adhesives are Epicoat 1001 / Epicoat 828 / Nipol 1032 (nitrile rubber, Nippon Zeon Co., Ltd.) / Hitanol 2400 (alkylphenol, Hitachi Chemical Co., Ltd.) / Cureazole 2PZ (2-phenylimidazole, Shikoku Kasei Co., Ltd.) )) = The thermosetting epoxy resin obtained by coating and drying a film-forming adhesive toluene solution having a compounding ratio of 50/20/20/10/2 was used.
[0041]
The production process is specifically shown in each example, but an applicator type coating machine was used for coating the adhesive material and the film-forming adhesive. Drying conditions after application of the thermosetting epoxy resin were 80 ° C. for 10 minutes. At this time, the film thickness was adjusted to about 25 μm by adjusting the concentration of the thermosetting epoxy resin and the coating gap of the applicator type coating machine. When the cross-sectional shape was observed, it was a two-layered film having a thermosetting epoxy resin layer of about 15 μm on one conductive particle layer fixed on the adhesive material surface.
[0042]
Evaluation of the obtained anisotropically conductive resin film-like molded product was as follows: a flexible circuit board (FPC) having a total circuit width of 50 mm having a copper circuit with a line width of 50 μm, a pitch of 100 μm and a thickness of 35 μm, a line width of 50 μm, a pitch of 100 μm, Using a glass substrate wiring board with a total circuit width of 50 mm having a transparent electrode circuit (ITO, Indium Tin Oxide) with a thickness of 0.1 μm, and aligning the circuits of the wiring boards facing each other, this circuit Insert the anisotropic conductive resin film adhesive obtained in the middle and pressurize and heat (10kg / cm ² , 170 ° C.) for 20 seconds, and the circuit was adhered with a sample for evaluation.
[0043]
As shown in FIGS. 1 (e) and 4 (e), the apparatus used for this bonding is a hot plate 14 on which a sample is placed on a fixed plate 15 at room temperature and heated to a constant temperature from above. The sample has a structure in which the sample is pressed and bonded, and the anisotropic conductive resin film adhesive was inserted so that the surface with few conductive particles 1 faced up and heated from the adhesive surface side. Connection resistance and insulation resistance were evaluated at room temperature and normal pressure. Measurement conditions were such that the connection resistance between a pair of FPCs was measured at a measurement current of 1 mA, and the insulation resistance between adjacent connection circuits was measured at a measurement voltage of 100V. The results are shown in Table 1 for all examples and comparative examples.
[0044]
Example 1
Plastic conductive particles were sprayed on the surface of the PET film coated with a silicone-based adhesive using a dry particle spraying device that sprays the powder through a sieve having an opening of 20 μm. A thermosetting epoxy resin solution was applied to the particle spreading surface and then dried.
[0045]
Example 2
Using a dry particle spraying device, a mask (non-charged nylon mesh with an opening of 15 μm) is closely attached to the surface of the PET film coated with a silicone adhesive, and the powder is sprayed through a sieve with an opening of 20 μm. Conductive particles were dispersed on the mask surface. After spraying, particles on the mask were rolled using a static elimination brush so that many particles entered the through holes of the mask. Next, after removing particles not held by the adhesive material by blowing compressed air, the mask was peeled from the adhesive material surface. A thermosetting epoxy resin solution was applied to the particle spreading surface and then dried.
[0046]
Example 3
Plastic conductive particles were sprayed on the surface of the PET film coated with a silicone-based adhesive using a dry particle spraying device that sprays the powder through a sieve having an opening of 20 μm. At this time, about 3 to 10 dispersed conductive particles aggregated to locally form a layered portion at various places. Cover this particle-spreading surface with a 25 μm PET cover film and insert it between rubber rolls, 1 kg / cm ² Pressed with a pressure of. After this, the cover PET film was peeled off, and the state of spraying of the conductive particles was observed. The child is It was almost pressed into one layer by being pressed against the adhesive material surface. A thermosetting epoxy resin solution was applied to the particle spreading surface and then dried.
[0047]
Example 4
Plastic conductive particles were sprayed on the aluminum foil using a dry particle spraying device that sprays the powder through a sieve having an opening of 20 μm. An acrylic plate charged to +3 kV using a corona charging device was placed above the conductive particle distribution surface so as to face the conductive particle distribution surface at a distance of about 1 cm. At this time, the conductive particles on the aluminum foil were adsorbed on the acrylic plate surface by electrostatic force. Further, since the conductive particles adsorbed on the acrylic plate surface are charged at the same potential, repulsive force due to static electricity is generated between the conductive particles, and there is no aggregation between the particles, so that one particle layer is formed. The particle surface was pressed against the silicone-based pressure-sensitive adhesive surface to transfer the conductive particles to the pressure-sensitive adhesive surface. The particle transfer surface was coated with a thermosetting epoxy resin solution and then dried.
[0048]
Example 5
Plastic conductive particles were sprayed on the aluminum foil using a dry particle spraying device that sprays the powder through a sieve having an opening of 20 μm. Next, the mask surface side of the plate on which the acrylic plate and the mask (mesh made of Ni plating having an opening of 15 μm and a thickness of 5 μm) are bonded is charged to +3 kV using a corona charging device, and the mask is placed above the conductive particle dispersion surface. The surface was set so as to face the conductive particle spraying surface with a distance of about 1 cm. At this time, the conductive particles on the aluminum foil were adsorbed to the through-hole portion of the mask by electrostatic force. Further, since the conductive particles adsorbed on the mask surface are charged to the same potential, repulsive force due to static electricity is generated between the conductive particles, there is no aggregation between the particles, and one particle layer is formed. The particle surface was pressed against the silicone adhesive material surface to transfer the conductive particles to the adhesive material surface. The particle transfer surface was coated with a thermosetting epoxy resin solution and then dried.
[0049]
Example 6
The plastic conductive particles were sprayed on the aluminum foil by using a dry particle spraying device that sprays the powder through a sieve having an opening of 20 μm. Next, the mask surface side of the mask (made of nylon, mesh opening 15 μm) adhered to the silicone-based adhesive material application surface on the PET film is charged to +3 kV using a corona charging device, and above the conductive particle distribution surface. The mask surface was placed at a distance of about 1 cm so as to face the conductive particle spray surface. At this time, the conductive particles on the aluminum foil entered the holes of the mask by electrostatic force, and were adhesively fixed to the adhesive material. Further, since the conductive particles fixed on the adhesive material surface are charged to the same potential, a repulsive force due to static electricity is generated between the conductive particles, and there is no aggregation between the particles, forming a single particle layer. Next, the mask was peeled from the adhesive material surface. A thermosetting epoxy resin solution was applied to the particle spreading surface and then dried.
[0050]
Example 7
The fibrous conductor was sprayed on the aluminum foil using a dry particle spraying device that sprays the powder through a sieve having an opening of 20 μm. Next, the surface of the mask (Ni-plated mesh having an opening of 15 μm and a thickness of 5 μm) in close contact with the silicone-based adhesive coating surface on the PET film is charged to +3 kV using a corona charging device, so that the fibrous conductive Above the body, the mask surface was placed at a distance of about 1 cm so as to face the fiber conductor spraying surface. At this time, the fibrous conductor on the aluminum foil entered the hole of the mask by electrostatic force and was adhesively fixed to the adhesive material. At this time, the fibrous conductor was almost upright on the surface of the adhesive material, and was fixed in a state of being buried by several μm in the adhesive material. In addition, since the fibrous conductors fixed to the adhesive material surface are charged to the same potential, repulsive force due to static electricity is generated between the fibrous conductors, and there is no aggregation between the fibrous conductors so that one conductor layer is formed. Was forming. Next, the mask was peeled from the adhesive material surface. A thermosetting epoxy resin solution was applied to the particle spreading surface and then dried. This film had a thickness of about 25 μm, and was a film having a two-layer structure in which a thermosetting epoxy resin layer of about 15 μm was formed on one fibrous conductor layer fixed to the adhesive material surface.
[0051]
Example 8
The insulating coated conductive particles were sprayed on the surface of the PET film coated with the silicone-based adhesive using a dry particle spraying device that sprays the powder through a sieve having an opening of 20 μm. A thermosetting epoxy resin solution was applied to the particle spreading surface and then dried.
Comparative example
As shown in FIG. 5, 30% by volume of the plastic conductive particles 1 are dispersed in the thermosetting epoxy resin solution of the film-forming adhesive 10, and the Teflon base film 3 is used by using an applicator coating apparatus. After casting on the top, it was dried. This film had many conductive particle aggregates and large irregularities on the surface, but the average film thickness was about 25 μm.
[0052]
[Table 1]

Note) A is the rate of occurrence of poor connection resistance (10Ω or more) (%)
B is defective insulation resistance (10 ⁶ Occurrence rate (% or less)
[0053]
【The invention's effect】
According to the present invention, since the conductive particles in the anisotropic conductive resin film adhesive have a single layer structure and the amount of conductive particles in the film can be increased, the conductive point per unit area of the adhesive can be increased. An anisotropic conductive resin film-like adhesive having an excellent decomposition performance as compared with the conventional one can be obtained, and high-definition electrical connection between electrodes can be achieved.
[Brief description of the drawings]
FIG. 1 shows the production order in the method for producing an anisotropic conductive resin film adhesive of the present invention. Introduction FIG.
FIG. 2 is a cross-sectional view when a circuit is connected by an anisotropic conductive resin film adhesive, (a) using the adhesive obtained in the present invention, and (b) a conventional manufacturing method. This is a case where the adhesive obtained in (1) is used.
FIG. 3 is a cross-sectional view illustrating various production examples in the method for producing an anisotropic conductive resin film adhesive according to the present invention.
FIG. 4 is a cross-sectional view illustrating various production examples in the method for producing an anisotropic conductive resin film adhesive according to the present invention.
FIG. 5 is a cross-sectional view illustrating a conventional method for producing an anisotropic conductive resin film adhesive.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Conductive particle, 2 ... Adhesive material, 3 ... Base film, 4 ... Mask, 5 ... Through-hole, 6 ... Rubber roll, 7 ... Charged body, 8 ... Fibrous conductor, 9 ... Insulation coating conductive particle, DESCRIPTION OF SYMBOLS 10 ... Film-forming adhesive, 11 ... Circuit, 12 ... Electrode, 13 ... Space between electrodes, 14 ... Hot plate, 15 ... Fixed plate

Claims

In the method for producing an anisotropic conductive resin film adhesive having conductivity only in the thickness direction through conductive particles uniformly dispersed in the surface direction, the thickness is equal to or larger than the particle size of the conductive particles on the adhesive material surface. After the conductive particle layer is provided, the conductive particle layer is pressed against the adhesive material surface, the conductive particles are adhesively fixed to the adhesive material surface, and the film-forming adhesive material incompatible with the adhesive material is electrically conductive particles. A method for producing an anisotropic conductive resin film-like adhesive material, wherein the adhesive material is peeled off from the film-forming adhesive material after filling in between.

2. An anisotropic conductive resin film-like adhesive according to claim 1, wherein a film or a mesh having a through hole is provided on the adhesive material surface, and the conductive particles are adhesively fixed to the adhesive material surface in the through hole of the film or mesh. Law.

Conductive particles held by electrostatic force on the charged body, presses the charging member to the adhesive surface, the anisotropic conductive claim 1 Symbol mounting to transfer the conductive particles to the adhesive material surface resin film adhesive Manufacturing method.

4. An anisotropic conductive resin film adhesive according to claim 3 , wherein a film or net having a through hole is provided on the charged body, and the conductive particles are held on the charged body in the through hole of the film or net by electrostatic force. Manufacturing method.

Conductive particles and an adhesive material is charged to a different electric charge, the conductive particles in the adhesive material surface sprayed by electrostatic force, providing the conductive particle layer according to claim 1 or 2 Symbol placement anisotropic conductive resin film adhesive Method of manufacturing the material.

Claim 3 using a fibrous conductor instead of the conductive particles, 4 or 5 Symbol preparation of the anisotropic conductive resin film adhesive mounting.

The method for producing an anisotropic conductive resin film adhesive according to any one of claims 1 to 6 , wherein the surface is previously coated with an electrically insulating layer capable of removing conductive particles or fibrous conductors by heating or pressing.

And the alignment between the electrodes, so as to have a substantially equal volume to the volume of space that occurs when brought into close contact with both circuits faced each other, any of claims 1 to 7 to adjust the thickness of the film forming adhesive material A method for producing the anisotropic conductive resin film adhesive according to claim 1.

The method for producing an anisotropic conductive resin film adhesive according to any one of claims 1 to 8 , wherein the concentration of the conductive particles is different in the thickness direction of the film.

When connecting the heat-pressed circuits between the oppositely connected circuits, the anisotropic conductive resin film-like adhesive obtained by the manufacturing method according to claim 9 is used, and the connection is performed by heating from a surface with a low concentration of conductive particles. A method for connecting between microcircuits.