JP3759294B2

JP3759294B2 - Electrode connection method

Info

Publication number: JP3759294B2
Application number: JP23486797A
Authority: JP
Inventors: 俊之柳川; 貢藤縄; 伊津夫渡辺
Original assignee: Hitachi Chemical Co Ltd; Showa Denko Materials Co Ltd
Current assignee: Showa Denko Materials Co Ltd
Priority date: 1997-08-29
Filing date: 1997-08-29
Publication date: 2006-03-22
Anticipated expiration: 2017-08-29
Also published as: JPH1174313A

Abstract

PROBLEM TO BE SOLVED: To enable connection at a low temperature and reduce thermal influence to a circuit member, by interposing a film-like circuit connection material containing photo-setting components and conductive particles between opposite first and the second connection terminals, and by electrically connecting the first and second connection terminals with each other by application of heat and pressure and light irradiation. SOLUTION: First and second connection terminals are oppositely placed, and a film-like circuit connection material containing photo-setting components and conductive particles is interposed between them. Then, the first and the second connection terminals are electrically connected with each other by application of heat and pressure and light irradiation. The film-like circuit connection material is mainly photo-cured, adhesive is melted and made to flow by the application of heat and pressure, and resin components in the vicinity of a part where the connection terminals and the conductive particles are in contact are sufficiently eliminated so that the conductive particles are sufficiently pressure-bonded between the connection terminals. Thus, heating may be performed to a temperature where the adhesive can flow, and a connection temperature of a circuit member can be lowered.

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば液晶パネル等少なくとも一方が光透過性を有する回路部材において、２つの回路部材同士の電極について優れた接着力や良好な電気的導通を得、さらに接続不良が生じた場合に良好な回路補修性を得るために、光硬化成分を含有するフィルム状回路接続材料を用いて、加熱加圧および光照射を同時あるいは別個に用いる電極の接続方法に関する。
【０００２】
【従来の技術】
フィルム状回路接続材料は、金属粒子等の導電性粒子を所定量含有した接着剤からなるもので、このフィルム状回路接続材料を電子部品と電極や回路の間に設け、加圧または加熱加圧を行うことによって、両者の電極同士が電気的に接続されると共に、隣接電極間の絶縁性を付与して、電子部品と回路とが接着固定されるものである。フィルム状回路接続材料に用いられる接着剤としては、スチレン系やポリエステル系等の熱可塑性物質や、エポキシ系やシリコーン系等の熱硬化性物質が知られている。これらの物質を含む接着剤を硬化させるには硬化剤が必要であり、さらにその硬化剤には、フィルム状回路接続材料の保存安定性を高めるために、常温では不活性であり、活性温度以上でのみ反応するという潜在性が伴っていなければならない。このため接着剤を硬化させるためには、樹脂成分の流動性の向上および硬化反応の促進のための加熱加圧が必要となる。すなわち、接着剤を溶融、流動させ、導電性粒子を変形して回路との接触面積を増大し、かつ回路部材との密着性を高めるために温度や圧力が必要となり、これらは接着剤の種類や硬化成分による。この他にフィルム状以外の形態を有する回路接続材料としては、光硬化性樹脂を用いたペースト状材料が知られているが、これらの回路接続材料は加圧もしくは加熱加圧によって回路部材を接続し、その後光照射によって接着剤を硬化させることを特徴としている。
【０００３】
また、これらの接着剤による接続において、電気的接続不良であったり接続後に電子部品や回路が不良になると、回路間を剥がす等した後で接着剤を溶剤等で除去した後に、再度良品を接着剤によって接続することが行われている。この場合、微細回路や電極上の接着剤を汎用溶剤（例えばアセトン、メチルエチルケトン、トルエン、リグロイン、テトラヒドロフラン、アルコール等）を用いて、周辺部の良好部に悪影響を与えず、迅速かつ容易に除去できることが重要である。接着剤が熱硬化性物質等の場合、溶剤として例えば塩化メチレンと酸等より成るいわゆるエポキシ剥離剤を用いる場合が多い。
【０００４】
【発明が解決しようとする課題】
しかしながら、樹脂硬化の際の加熱加圧に伴う回路部材に対する熱や圧力の影響はその大小を問わず存在し、特に熱的な影響に関しては、回路部材自体への影響のみならず、回路部材接続時の影響も大きい。すなわち、加熱加圧時の温度が高い条件で接続を行うと、対向する２つの回路部材が異なっておりそれぞれの熱膨張係数（α）の差が大きい場合には、回路の位置ずれが発生する可能性が高くなる。また回路の補修に関して、従来用いていた熱硬化性の接着剤では、溶剤として例えば塩化メチレンと酸等より成るいわゆるエポキシ剥離剤および汎用溶剤を用いて補修していたが、前者の場合は基板回路等への悪影響があり、後者の場合には接着剤によっては補修が不可能であるか、または補修に要する時間が長くなることがあり、作業性を低下させる。本発明はこのような状況に鑑みなされたもので、従来より低温での接続が可能で回路部材に対する熱的影響を軽減し、かつ接続部の信頼性が高く、さらには接続不良が発生した場合には汎用溶剤によって短時間で容易に補修可能な、フィルム状回路接続部材を用いた電極の接続方法を提供するものである。
【０００５】
【課題を解決するための手段】
本発明の電極の接続方法は、少なくとも一方が光透過性を有する２つの回路部材、すなわち第一の接続端子を有する第一の回路部材と、第二の接続端子を有する第二の回路部材とを、第一の接続端子と第二の接続端子を対向して配置し、前記対向配置した第一の接続端子と第二の接続端子の間に、光硬化成分および導電性粒子を含有するフィルム状回路接続材料を介在させ、加熱加圧および光照射を行い、前記対向配置した第一の接続端子と第二の接続端子を電気的に接続させることを特徴とする。フィルム状回路接続材料は光硬化性樹脂、分子量が１０，０００以上の高分子樹脂および導電性粒子を必須成分とするものが使用され、更にカップリング剤を含有することができる。本発明では、加熱加圧および光照射によって、フィルム状回路接続材料が溶融、流動し、導電性粒子による回路部材間の導通が確保されるような条件で第一の接続端子と第二の接続端子を電気的に接続させる一次接続を行った後、加熱加圧および光照射を中断し、導通検査による一定時間経過後、再び光照射によって十分な硬化を行うことにより電極を接続する。また、加熱加圧によって、フィルム状回路接続材料が溶融、流動し、導電性粒子による回路部材間の導通が確保されるような条件で第一の接続端子と第二の接続端子を電気的に接続させる一次接続を行った後加熱加圧を中断し、導通検査による一定時間経過後、光照射によって十分な硬化を行うことにより電極を接続する。前記一次接続を行った後、フィルム状回路接続材料のガラス転移点以下にまで冷却を行い、その後加圧および光照射を中断することができる。加熱加圧と光照射を同時に開始するようにしたり、加熱加圧と光照射の間に１〜数秒の間隔を設け、加熱加圧開始後に光照射を行うようにすることができる。光透過性を有する回路部材の厚みが１．２ｍｍ以下であるのが好ましく、導電性粒子の圧縮弾性率は、１０００〜１００００ＭＰａであることが好ましい。
【０００６】
本発明の電極の接続方法は、少なくとも一方が光透過性を有する２つの回路部材、すなわち第一の接続端子を有する第一の回路部材と、第二の接続端子を有する第二の回路部材とを、第一の接続端子と第二の接続端子を対向して配置し、前記対向配置した第一の接続端子と第二の接続端子の間に、光硬化成分および導電性粒子を含有するフィルム状回路接続材料を介在させ、加熱加圧および光照射を併用することによって、前記対向配置した第一の接続端子と第二の接続端子を電気的に接続させることを特徴とし、これらのフィルム状回路接続材料の構成成分が光硬化性樹脂、分子量が１０，０００以上の高分子樹脂および導電性粒子を必須成分とすることを特徴とするものである。また、加熱加圧および光照射によって、フィルム状回路接続材料が溶融、流動し、導電性粒子による回路部材間の導通が確保されるような条件で第一の接続端子と第二の接続端子を電気的に接続させる一次接続を行った後、加熱加圧および光照射を中断し、導通検査等による一定時間経過後、再び光照射のみによって十分な硬化を行うことを特徴とするものである。
【０００７】
【発明の実施の形態】
本発明において、回路部材としては半導体チップ、抵抗体チップ、コンデンサチップ等のチップ部品、プリント基板等の基板、液晶パネル等が用いられる。これらの回路部材には接続端子が通常は多数（場合によっては単数でも良い）設けられており、少なくとも一方が光透過性を有する前記回路部材の少なくとも１組を、それらの回路部材に設けられた接続端子の少なくとも１部を対向配置し、対向配置した接続端子間に接着剤を介在させ、加熱加圧および光照射して対向配置した接続端子同士を電気的に接続して接続体とする。この時、光透過性を有する回路部材の厚みは、１．２ｍｍ以下が光透過性の面で好ましい（請求項７）。また、光硬化性樹脂を含有する回路接続材料の形態をフィルム状とすることで、従来のペースト状回路接続材料に比べて取扱い性が優れている点や接続厚みの均一化が図れる点等で有利である。さらに、回路部材との密着性を高めるために、硬化反応がほとんど進行せず樹脂が流動する程度の加熱を行う場合、接続材料の加熱を行って接続端子−導電性粒子−接続端子間の導通を確保した後、冷却工程を導入することによって接続材料の溶融粘度を再上昇させることが可能であり、これによって加熱−冷却のみによる導電性粒子の圧接状態を維持し樹脂の固定が図れる。これはペースト状の回路接続材料では不可能である。
【０００８】
請求項１、および請求項２に示した方法では、一次接続において、第一の接続端子と第二の接続端子とを対向配置し、その間に光硬化成分および導電性粒子を含有するフィルム状回路接続材料を介在させ、加熱加圧および光照射、または加熱加圧によって前記対向配置した第一の接続端子と第二の接続端子を電気的に接続させる。フィルム状回路接続材料の硬化は主として光硬化によって行なわれるために、加熱加圧工程の役割としては、接着剤を溶融、流動させ、接続端子と導電性粒子が接触する部分周辺の樹脂成分を十分に排除し、接続端子間に導電性粒子を充分に圧接させることである、と考えることができる。このため接着剤のＴｇ以上、もしくは導電性粒子の十分な変形に必要な接着剤の流動が得られる温度まで加熱すればよく、その温度はフィルム形成材料である高分子樹脂の種類にもよるが、概ね８０〜１４０℃の範囲内である。これは従来の熱硬化性樹脂を硬化成分として用いているフィルム状回路接続材料の接続に必要な加熱温度である１５０〜１９０℃よりも低い。したがって上記方法によって回路部材の接続温度の低温化を図ることができる。また、加熱加圧と光照射を同時に行う場合は、接着剤の流動によって導電性粒子の接触を十分に行うために、溶融流動性と光照射能力との調整が必要である。ここでいう光照射能力は、用いる光照射装置の光源に依存しており、光量の少ない光源を使用している光照射装置の場合には、接着剤の硬化速度が遅くなり、その間に樹脂流動が十分に行なわれるため、加熱加圧と光照射を全く同時に行うことができる（請求項５）。また光量の多い光源を使用している光照射装置の場合には、樹脂流動を優先させるために加熱加圧工程と光照射工程の間に１〜数秒の間隔を設け、加熱加圧開始後に光照射を行うこともできる（請求項６）。この場合光照射を遅延して行うため、樹脂が流動し導電性粒子による接続端子の導通が確保された後、光量を増加して短時間で急速に硬化させてもよい。
【０００９】
光硬化性樹脂、分子量が１０，０００以上の高分子樹脂および導電性粒子を必須成分とすることによって、光硬化が可能なフィルム状の回路接続材料を提供することが可能である。これは、分子量が１０，０００以上の高分子樹脂がほとんどが常温で固形であり、フィルム形成能力が高いことに起因している。この高分子樹脂と光硬化性樹脂を混合することによって、従来の、光硬化性樹脂を用いた回路接続材料の短所であった、取扱い性の向上や接続厚みの均一化等を図ることが可能である。
【００１０】
光硬化性樹脂、分子量が１０，０００以上の高分子樹脂および導電性粒子を必須成分とするフィルム状回路接続材料を用い、加熱加圧および光照射によって、フィルム状回路接続材料が溶融、流動し、導電性粒子による回路部材間の導通が確保されるような条件で第一の接続端子と第二の接続端子を電気的に接続させる一次接続を行った後、加熱加圧および光照射を中断し、導通検査等による一定時間経過後、再び光照射のみによって十分な硬化を行う請求項１に示した方法、また、加熱加圧のみによって、前記フィルム状回路接続材料が溶融、流動し、導電性粒子による回路部材間の導通が確保されるような条件で第一の接続端子と第二の接続端子を電気的に接続させる一次接続を行った後加熱加圧を中断し、導通検査等による一定時間経過後、光照射のみによって十分な硬化を行う請求項２に示した方法においては、初期導通を確保するには導電性粒子の変形が十分であり、かつその状態が加熱加圧終了後も維持されていることが重要であることから、導通を確保するのに最低限必要な加熱加圧および光照射を行えばよい。この時の加熱加圧条件は、温度の場合は前述したように接着剤のＴｇ以上、もしくは導電性粒子の十分な変形に必要な接着剤の流動が得られる温度まで加熱できる条件が好ましく、その温度はフィルム形成材料である高分子樹脂の種類にもよるが、８０〜１４０℃の範囲内が好ましい。また圧力は回路部材の種類によって変化するが、回路部材に悪影響を与えず、なおかつ導電性粒子を変形させることができる条件が好ましい。一次接続を行った時点で導通検査を行い、その結果初期抵抗が高く導通が確保できていなければ、回路部材を剥離して回路を補修することになるが、接着剤の硬化はまだ十分に進行していないため、汎用溶剤で非常に短時間に接着剤を除去することが可能である。逆に、導通が確保されていれば未硬化である接着剤を光照射によって十分に硬化させればよい。
【００１１】
また、一次接続を行った後、フィルム状回路接続材料のＴｇ以下にまで冷却を行い、その後加圧および光照射、または加圧を中断することを特徴とする請求項３、または請求項４に示した方法では、圧力開放直前に熱圧着装置の加熱加圧ヘッドを冷却するため、接着剤が全く未硬化であるか、硬化反応がほとんど進行していない場合においても、冷却工程によって接着剤温度がＴｇ以下にまで低下し、溶融粘度も再び上昇するため、圧力開放時の導電性粒子の復元を抑制し、接続厚みが保たれることから導通を確保することが可能である。逆に、接着剤が同様な状態であるとき、冷却工程を経ない場合においては、接着剤温度がＴｇ以上であり、溶融粘度も低くなっているため、圧力解放時に接続厚みが増加し、回路間に気泡が多数発生して接着性の低下を招く。また、接続厚みの増加によって導電性粒子が復元し、回路との接触面積が減少するため、初期抵抗が著しく上昇し、導通が確保できない。
【００１２】
本発明に用いるフィルム状回路接続材料としては光硬化性樹脂に、フィルム形成性を付与するための固形高分子樹脂を混合した接着剤成分、そして導電性粒子から成っており、接続材料をフィルム状とすることで回路部材接続時の取扱い性の向上を図ることができる。
【００１３】
本発明に用いる光硬化性樹脂としては、エポキシアクリレートオリゴマー、ウレタンアクリレートオリゴマー、ポリエーテルアクリレートオリゴマー、ポリエステルアクリレートオリゴマー等の光重合性オリゴマー、トリメチロールプロパントリアクリレート、ポリエチレングリコールジアクリレート、ポリアルキレングリコールジアクリレート、ペンタエリスリトールアクリレート等の光重合性多官能アクリレートモノマー等といったアクリル酸エステル、およびこれらと類似したメタクリル酸エステル等に代表される光重合型の樹脂があり、必要に応じてこれらの樹脂を単独あるいは混合して用いてもよいが、接着剤硬化物の硬化収縮を抑制し、柔軟性を与えるためにはウレタンアクリレートオリゴマーを配合するのが好ましい。また上述した光重合性オリゴマーは高粘度であるために、粘度調整のために低粘度の光重合性多官能アクリレートモノマー等のモノマーを配合するのが好ましい。
【００１４】
これらの光硬化性樹脂は光開始剤を用いて重合、硬化させる。本発明に用いる光開始剤としてはベンゾインエチルエーテル、イソプロピルベンゾインエーテル等のベンゾインエーテル、ベンジル、ヒドロキシシクロヘキシルフェニルケトン等のベンジルケタール、ベンゾフェノン、アセトフェノン等のケトン類およびその誘導体、チオキサントン類、ビイミダゾール類等があり、これらの光開始剤に必要に応じてアミン類、イオウ化合物、リン化合物等の増感剤を任意の比で添加してもよい。この際、用いる光源の波長や所望の硬化特性等に応じて最適な光開始剤を選択する必要がある。また、これらの光硬化性樹脂とポリエチレン、酢酸エチル、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等の熱硬化性樹脂、あるいはフェノキシ樹脂やエラストマー等とを混合して用いることができる。
【００１５】
硬化に用いる光は、一般的に広く使用されている紫外線を用いることができ、水銀ランプ、メタルハライドランプ、無電極ランプ等で発生させることができる。また、硬化反応としてラジカル反応を用いた場合、酸素が反応禁止剤として作用するので、光照射の雰囲気中の酸素量は光硬化性樹脂の硬化に影響を与える。これは光硬化性樹脂、光開始剤、増感剤等の種類や濃度にも大きく左右されるので、個々の配合系で詳細に検討する必要がある。
【００１６】
導電性粒子としては、Ａｕ、Ａｇ、Ｎｉ、Ｃｕ、はんだ等の金属粒子やカーボン等があり、これらおよび非導電性のガラス、セラミック、プラスチック等に前記した導通層を被覆等によって形成したものでもよい。プラスチックを核とした場合や熱溶融金属粒子の場合、加熱加圧によって変形性を有するので接続時に電極との接触面積が増加し信頼性が向上するので好ましい。導電性粒子は、接着剤成分１００体積に対して、０．１〜３０体積％の広範囲で用途によって使い分ける。過剰な導電性粒子による隣接回路の短絡等を防止するためには、０．２〜１５体積％とするのがより好ましい。この時の導電性粒子の平均粒径は、その添加量にもよるが１〜１５μｍとするのがより好ましい。また導電性粒子の圧縮弾性率は、加熱加圧および光照射を中断した時に、接着剤の弾性による粒子の復元を抑制するために、１０００〜１００００ＭＰａの範囲内とすることが好ましい。
【００１７】
シランカップリング剤としてはビニルトリクロルシラン、ビニルトリエトキシシラン、ビニル−トリス−（βメトキシエトキシ）シラン、γ−メタクリロキシプロピルトリメトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシラン、β−（３，４エポキシシクロヘキシル）エチルトリメトキシシラン、イソイアン酸プロピルトリエトキシシラン等があるが、光硬化性樹脂との反応性を高めるにはγ−メタクリロキシプロピルトリメトキシシランを用いるのがより好ましい。
【００１８】
【実施例】
実施例１
フェノキシ樹脂（ユニオンカーバイド株式会社製、商品名ＰＫＨＡ）４０ｇを、重量比でトルエン（沸点１１０．６℃、ＳＰ値８．９０）／酢酸エチル（沸点７７．１℃、ＳＰ値９．１０）＝５０／５０の混合溶剤６０ｇに溶解して、固形分４０％の溶液とした。光硬化性樹脂は、エポキシアクリレートオリゴマー（新中村化学工業株式会社製、商品名ＮＫオリゴＥＡ−１０２０）およびアクリレートモノマー（新中村化学工業株式会社製、商品名ＮＫエステルＡ−ＴＭＭ−３Ｌ）を、３／１の重量比で用いた。光開始剤はベンゾフェノンを用い、これに増感剤として４，４’−ビスジエチルアミノベンゾフェノン（保土ケ谷化学工業株式会社製、商品名ＥＡＢ）を、光開始剤／増感剤＝５／１となるように混合して用いた。ポリスチレンを核とする粒子の表面に、厚み０．２μｍのニッケル層を設け、このニッケル層の外側に、厚み０．０２μｍの金層を設け、平均粒径５μｍ、比重２．５の導電性粒子を作製した。固形重量比でフェノキシ樹脂５０、光硬化性樹脂５０、光開始剤５、増感剤１となるように配合し、さらに導電性粒子を３体積％配合分散させ、厚み８０μｍのフッ素樹脂フィルムに塗工装置を用いて塗布し、７０℃、１０分の熱風乾燥によって接着剤層の厚みが２０μｍのフィルム状回路接続材料を得た。上記製法によって得たフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、紫外線照射併用型熱圧着装置（加熱方式：コンスタントヒート型、東レエンジニアリング株式会社製）を用いて図１に示すように１３０℃、２ＭＰａで２０秒間の加熱加圧およびＩＴＯガラス側からの紫外線照射を同時に行って幅２ｍｍにわたり接続し、時間経過後圧力開放して、接続体を作製した。接着剤に照射される紫外線量（以下紫外線照射量）は１．３Ｊ／ｃｍ2とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。
【００１９】
実施例２
実施例１によって得たフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、パルスヒート型熱圧着装置（日本アビオニクス株式会社製）を用いて、図２に示すように１３０℃、２ＭＰａで２０秒間加熱加圧して幅２ｍｍにわたり接続した後、約５０℃までエアによって加熱ヘッドを冷却した後に圧力を開放し、これを接続終了とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。上記方法によって得た接続体に、紫外線照射装置（ウシオ電機株式会社製）を用いて、図３に示すようにＩＴＯガラス側から紫外線を照射して接続体を作製した。この時の紫外線照射量は１．３Ｊ／ｃｍ2とした。
【００２０】
実施例３
実施例１によって得たフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、紫外線照射併用型熱圧着装置（加熱方式：コンスタントヒート型、東レエンジニアリング株式会社製）を用いて図１に示すように１３０℃、２ＭＰａで１０秒間の加熱加圧およびＩＴＯガラス側からの紫外線照射を同時に行って幅２ｍｍにわたり接続し、時間経過後圧力開放して、接続体を作製した。紫外線照射量は１．３ｍＪ／ｃｍ2とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。上記方法による接続後、初期接続抵抗等の導通検査を行い、検査終了後同装置を用いて１３０℃、２ＭＰａで１０秒間の加熱加圧および照射量１．３Ｊ／ｃｍ2の紫外線照射を同時に行い、時間経過後圧力開放して接続体を作製した。上記方法による接続後、初期接続抵抗等の導通検査を行い、検査終了後同装置を用いて１３０℃、２ＭＰａで１０秒間の加熱加圧および照射量１．３Ｊ／ｃｍ2の紫外線照射を同時に行い、時間経過後圧力開放して接続体を作製した。
【００２１】
実施例４
実施例１によって得たフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、紫外線照射併用型熱圧着装置（加熱方式：コンスタントヒート型、東レエンジニアリング株式会社製）を用いて図１に示すように１３０℃、２ＭＰａで３秒間の加熱加圧およびＩＴＯガラス側からの紫外線照射を同時に行って幅２ｍｍにわたり接続し、時間経過後圧力開放して、接続体を作製した。紫外線照射量は１．３Ｊ／ｃｍ2とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。上記方法による接続後、初期接続抵抗等の導通検査を行った結果、導通不良であることが確認されたので、検査終了後回路の補修を行い、実施例１と同様に同装置を用いて１３０℃、２ＭＰａで２０秒間の加熱加圧および照射量１．３Ｊ／ｃｍ2の紫外線照射を同時に行い、時間経過後圧力開放して接続体を作製した。
【００２２】
実施例５
実施例１によって得たフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、紫外線照射併用型熱圧着装置（加熱方式：コンスタントヒート型、東レエンジニアリング株式会社製）を用いて図１に示すように１３０℃、２ＭＰａで１０秒間の加熱加圧およびＩＴＯガラス側からの紫外線照射を同時に行って幅２ｍｍにわたり接続し、時間経過後圧力開放して、接続体を作製した。紫外線照射量は５．０Ｊ／ｃｍ2とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。図１における１０秒間の接続の際、加熱加圧のみを開始して２秒経過した後８秒間の紫外線照射を開始し、加熱加圧１０秒後に２工程が同時に終了するようにした。
【００２３】
実施例６
実施例１で使用したフィルム状回路接続材料の導電性粒子を、平均粒径５μｍのニッケル粒子（大同特殊綱株式会社製、商品名ＤＳＰ３１０１、比重８．５）に代えた他は、実施例１と同様にして接続体を作製した。
【００２４】
実施例７
実施例１で使用したフィルム状回路接続材料の光硬化性樹脂を、ウレタンアクリレートオリゴマー（新中村化学工業株式会社製、商品名ＮＫオリゴＵＡ−５１２）およびアクリレートモノマー（Ａ−ＴＭＭ−３Ｌ）に代えた他は、実施例１と同様にして接続体を作製した。
【００２５】
比較例１
実施例１で使用したフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、コンスタントヒート型熱圧着装置（当社製）を用いて１３０℃、２ＭＰａで２０秒間加熱加圧して幅２ｍｍにわたり接続し、時間経過後圧力開放して、これを接続終了とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。上記方法によって得た接続体に、実施例２で用いた紫外線照射装置を用いて、図３に示すようにＩＴＯガラス側から紫外線を照射して接続体を作製した。この時の紫外線照射量は１．３Ｊ／ｃｍ2とした。
【００２６】
比較例２
実施例１で使用したフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、紫外線照射併用型熱圧着装置（加熱方式：コンスタントヒート型、東レエンジニアリング株式会社製）を用いて図１に示すように１３０℃、２ＭＰａで１０秒間の加熱加圧およびＩＴＯガラス側からの紫外線照射を同時に行って幅２ｍｍにわたり接続し、時間経過後圧力開放して、接続体を作製した。紫外線照射量は５．０Ｊ／ｃｍ2とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。
【００２７】
比較例３
実施例１〜６、比較例１〜２で使用したフィルム状回路接続材料の配合樹脂であるフェノキシ樹脂と、マイクロカプセル型潜在性硬化剤を含有する液状エポキシ樹脂を、固形重量比でフェノキシ樹脂５０、液状エポキシ樹脂５０となるように配合し、さらに実施例１で用いた導電性粒子を３体積％配合分散させ、厚み８０μｍのフッ素樹脂フィルムに塗工装置を用いて塗布し、７０℃、１０分の熱風乾燥によって接着剤層の厚みが２０μｍのフィルム状回路接続材料を得た。上記製法によって得たフィルム状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、コンスタントヒート型熱圧着装置（当社製）を用いて１３０℃、２ＭＰａで２０秒間加熱加圧して幅２ｍｍにわたり接続し、時間経過後圧力開放して、これを接続終了とした。この時、あらかじめＩＴＯガラス上に、フィルム状回路接続材料の接着面を貼り付けた後、７０℃、０．５ＭＰａで５秒間加熱加圧して仮接続し、その後、フッ素樹脂フィルムを剥離してもう一方の被着体であるＦＰＣと接続した。
【００２８】
比較例４
光硬化性樹脂は、エポキシアクリレートオリゴマー（新中村化学工業株式会社製、商品名ＮＫオリゴＥＡ−１０２０）およびアクリレートモノマー（新中村化学工業株式会社製、商品名ＮＫエステルＡ−ＴＭＭ−３Ｌ）を、３／１の重量比で用い、光開始剤にはベンゾフェノンを用い、これに増感剤として４，４’−ビスジエチルアミノベンゾフェノン（保土ケ谷化学工業株式会社製、商品名ＥＡＢ）を、光開始剤／増感剤＝５／１となるように混合して用いた。また、ポリスチレンを核とする粒子の表面に、厚み０．２μｍのニッケル層を設け、このニッケル層の外側に、厚み０．０２μｍの金層を設け、平均粒径５μｍ、比重２．５の導電性粒子を作製した。これらを用い、固形重量比で光硬化性樹脂１００、光開始剤５、増感剤１となるように配合し、さらに導電性粒子を３体積％配合分散させ、ペースト状回路接続材料を得た。上記製法によって得たペースト状回路接続材料を用いて、ライン幅５０μｍ、ピッチ１００μｍ、厚み１８μｍの銅回路を５００本有するフレキシブル回路板（ＦＰＣ）と、０．２μｍの酸化インジウム（ＩＴＯ）の薄層を形成したガラス（厚み１．１ｍｍ、表面抵抗２０Ω／□）とを、パルスヒート型熱圧着装置（日本アビオニクス株式会社製）を用いて１３０℃、２ＭＰａで２０秒間加熱加圧して幅２ｍｍにわたり接続し、時間経過後圧力開放して、これを接続終了とした。この時、あらかじめＩＴＯガラス上に、ペースト状回路接続材料を適量塗布し、もう一方の被着体であるＦＰＣと接続した。上記方法によって得た接続体に、紫外線照射装置（ウシオ電機株式会社製）を用いて、図３に示すようにＩＴＯガラス側から紫外線を照射して接続体を作製した。この時の紫外線照射量は１．３Ｊ／ｃｍ2とした。
【００２９】
実施例１〜７、比較例１〜４で得た接続体について初期抵抗、接着性および回路の補修性について評価した。初期抵抗については、回路部材の接続後、上記接続部を含むＦＰＣの隣接回路間の抵抗値を、マルチメータで測定した。測定電流は１ｍＡとし、抵抗値は隣接回路間の抵抗１５０点の平均（ｘ＋３σ）で示した。ＦＰＣならびにＩＴＯガラスに対する接着性については、接着力をＪＩＳ−Ｚ０２３７に準じて９０度剥離法で測定し、評価した。測定装置は東洋ボールドウィン株式会社製テンシロンＵＴＭ−４（剥離速度５０ｍｍ／ｍｉｎ、２５℃）を使用した。また回路補修性については、上記接続部のＦＰＣをＩＴＯガラスから剥離し、ＩＴＯガラス上に残存する一定面積（２０×２ｍｍ）の接着剤を、アセトンを含浸した綿棒で拭き取り、終わるまでに要した時間で評価した。
【００３０】
これらの結果をすべての実施例、比較例について図４の表１に示した。加熱加圧と紫外線照射を同時に行っている実施例１では、初期抵抗、接着力のいずれも良好な値を示した。加熱加圧と紫外線照射を別個の装置を用い、同時に行っていない実施例２も、圧力解放前に接続体が十分に冷却されているために接続厚みの増加が抑えられ、低接続抵抗となっている。また、１０秒という実施例１、実施例２より短時間での接続である実施例３の場合には、接着剤の硬化反応が比較的進行しているために導電性粒子の復元が抑制され、接続抵抗に関しては問題ないが、さらに硬化反応を促進するために紫外線照射を行った結果、接着力についても良好な値を示した。実施例４の場合には、３秒間しか加熱加圧および紫外線照射を行わなかったため、導電性粒子の変形や硬化反応が不十分であり、初期抵抗が高くなった。そこでＦＰＣを剥離して回路の補修を行ったところ、接着剤が未硬化であるためにごく短時間で補修を行うことができた。これによって回路の再接続を手早く行うことが可能となる。さらに、紫外線照射量を５．０Ｊ／ｃｍ2に増加した実施例５の場合、樹脂の流動および導通の確保を優先するために光照射開始を２秒遅らせた結果、良好な接続特性が得られた。導電性粒子、光硬化性樹脂を代えた実施例６、実施例７においても良好な接続状態である。一方、冷却工程を設けていない接続方法である比較例１の場合、接着力に関しては紫外線照射によって十分に接着剤が硬化しているために実施例１〜４とほぼ同等の値を示しているが、冷却工程がないために接着剤が固定されないことから導電性粒子の変形が維持されず、回路部材との接触面積が小さくなるため、初期抵抗は著しく高くなっている。また、実施例５に対して、光照射量５．０Ｊ／ｃｍ2の条件下で加熱加圧と紫外線照射を同時に行った比較例２では、接着剤の硬化反応が樹脂の流動よりも早く進行するため、導電性粒子が回路部材に十分に接触しておらず、導通不良となった。さらに、熱硬化性樹脂を主成分とした接着剤を用いている比較例３では、１３０℃、２ＭＰａ、２０秒の接続条件では接着剤の反応率が低くなるため、十分な硬化が得られず、接着力がかなり低くなり初期抵抗も高くなった。比較例４の場合には、フィルム形成性を付与する高分子樹脂が含有されていないために、フィルム状回路接続材料を用いた場合に導通が確保されている実施例２と比較して、一次接続における冷却過程における導通の確保の点で劣っており、また取扱い性の点でフィルム状材料より不利であった。
【００３１】
【発明の効果】
本発明によれば、接着剤に光硬化性樹脂をおよび導電性粒子を必須成分とするフィルム状回路接続材料を介在させ、加熱加圧と同時に、あるいは加熱加圧後に光照射によって回路部材を接続するため、接続に要する温度を従来より低くすることが可能で、また加熱加圧後、圧力開放直前に接続体を冷却するため、導電性粒子の復元ならびに接続厚みの増加を抑制し、優れた接着力や良好な電気的導通を得ることができる。さらに初期接続の際に接続不良が発生した場合には、樹脂の硬化反応があまり進行していないので、汎用溶剤による回路補修を容易に行うことが可能である。
【図面の簡単な説明】
【図１】本発明のフィルム状回路接続材料を用いた接続方法（実施例）を説明する断面図である。
【図２】本発明のフィルム状回路接続材料を用いた接続方法（実施例）を説明する断面図である。
【図３】フィルム状回路接続材料を用いた接続方法（比較例）を説明する断面図である。
【図４】実施例１〜７、比較例１〜４で得た接続体について初期抵抗、接着性および回路の補修性についての評価結果を示す表である。
【符号の説明】
１…ＩＴＯガラス２…導電性粒子
３…ＦＰＣ回路４…ＦＰＣ基材
５…接着剤６…光源
７…光８…ベース
９…加熱加圧ヘッド１０…冷却用空気注入口[0001]
BACKGROUND OF THE INVENTION
The present invention, for example, in a circuit member in which at least one of the liquid crystal panels and the like has optical transparency, obtains excellent adhesive force and good electrical continuity with respect to the electrodes of the two circuit members, and is good when a connection failure occurs. In order to obtain excellent circuit repairability, the present invention relates to a method for connecting electrodes using a film-like circuit connecting material containing a photocuring component and simultaneously using heating and pressing and light irradiation separately.
[0002]
[Prior art]
The film-like circuit connection material is made of an adhesive containing a predetermined amount of conductive particles such as metal particles. This film-like circuit connection material is provided between an electronic component and an electrode or circuit, and is pressurized or heated and pressurized. By performing the above, both electrodes are electrically connected to each other, and insulation between adjacent electrodes is imparted, so that the electronic component and the circuit are bonded and fixed. As adhesives used for the film-like circuit connecting material, thermoplastic materials such as styrene and polyester, and thermosetting materials such as epoxy and silicone are known. In order to cure the adhesive containing these substances, a curing agent is required. Further, the curing agent is inactive at room temperature and is higher than the activation temperature in order to enhance the storage stability of the film-like circuit connecting material. It must be accompanied by the potential to react only with. For this reason, in order to cure the adhesive, it is necessary to apply heat and pressure to improve the fluidity of the resin component and accelerate the curing reaction. That is, the temperature and pressure are required to melt and flow the adhesive, deform the conductive particles to increase the contact area with the circuit, and improve the adhesion to the circuit member. Depending on the curing component. In addition, paste materials using photo-curing resins are known as circuit connection materials having forms other than film-like, but these circuit connection materials connect circuit members by pressurization or heating and pressurization. The adhesive is then cured by light irradiation.
[0003]
In addition, in the connection with these adhesives, if the electrical connection is defective or the electronic component or circuit becomes defective after connection, the adhesive is removed again with a solvent etc. Connecting with agents is done. In this case, the adhesive on the microcircuits and electrodes can be removed quickly and easily using general-purpose solvents (for example, acetone, methyl ethyl ketone, toluene, ligroin, tetrahydrofuran, alcohol, etc.) without adversely affecting the good parts of the periphery. is important. When the adhesive is a thermosetting substance or the like, a so-called epoxy release agent composed of, for example, methylene chloride and an acid is often used as a solvent.
[0004]
[Problems to be solved by the invention]
However, the effects of heat and pressure on the circuit members due to heating and pressurization during resin curing exist regardless of their size. Especially regarding the thermal effects, not only the effects on the circuit members themselves, but also the connection of the circuit members. The influence of time is also great. That is, when the connection is performed under a condition where the temperature at the time of heating and pressurization is high, if the two facing circuit members are different and the difference in the thermal expansion coefficient (α) is large, a circuit misalignment occurs. The possibility increases. As for circuit repair, thermosetting adhesives that have been used in the past have been repaired using a so-called epoxy release agent composed of methylene chloride and acid as a solvent and a general-purpose solvent. In the latter case, the repair may not be possible depending on the adhesive, or the time required for the repair may become longer, and workability may be reduced. The present invention has been made in view of such a situation, and can be connected at a lower temperature than before, reduce the thermal influence on the circuit member, have high reliability of the connection portion, and further, when a connection failure occurs Provides an electrode connection method using a film-like circuit connection member that can be easily repaired in a short time with a general-purpose solvent.
[0005]
[Means for Solving the Problems]
The electrode connection method of the present invention includes at least one of two circuit members having optical transparency, that is, a first circuit member having a first connection terminal, and a second circuit member having a second connection terminal. The first connection terminal and the second connection terminal are arranged opposite to each other, and a film containing a photocuring component and conductive particles between the first connection terminal and the second connection terminal arranged opposite to each other. The first connection terminal and the second connection terminal that are arranged to face each other are electrically connected to each other by interposing a circuit-connecting material, heating and pressurization and light irradiation. As the film-like circuit connecting material, a photo-curing resin, a polymer resin having a molecular weight of 10,000 or more and conductive particles are used as essential components, and a coupling agent can be further contained. In the present invention, the first connection terminal and the second connection are provided under such conditions that the film-like circuit connection material melts and flows by heat and pressure and light irradiation, and conduction between the circuit members by the conductive particles is ensured. after electrically connected to the primary connection terminals, to interrupt the heating and pressing and light irradiation, after a certain period of time by conductivity test, connecting the electrodes by performing sufficient curing again by light irradiation. In addition, the first connection terminal and the second connection terminal are electrically connected under such conditions that the film-like circuit connection material melts and flows by heat and pressure, and conduction between the circuit members by the conductive particles is ensured. heating was discontinued pressure after primary connection for connecting, after a certain period of time by conductivity test, connecting the electrodes by performing sufficient curing by light irradiation. After the primary connection, cooling to below the glass transition point of the film-like circuit connecting material, it is possible to interrupt the subsequent pressing and light irradiation. Heating and pressing and light irradiation can be started simultaneously, or an interval of 1 to several seconds can be provided between heating and pressing and light irradiation, and light irradiation can be performed after the start of heating and pressing. The thickness of the circuit member having optical transparency is preferably 1.2 mm or less, and the compressive elastic modulus of the conductive particles is preferably 1000 to 10,000 MPa.
[0006]
The electrode connection method of the present invention includes at least one of two circuit members having optical transparency, that is, a first circuit member having a first connection terminal, and a second circuit member having a second connection terminal. The first connection terminal and the second connection terminal are arranged opposite to each other, and a film containing a photocuring component and conductive particles between the first connection terminal and the second connection terminal arranged opposite to each other. The film-like circuit connection material is interposed, and the first connection terminal and the second connection terminal arranged opposite to each other are electrically connected by using heating and pressurization and light irradiation in combination, and these film-like The constituent components of the circuit connecting material are a photocurable resin, a polymer resin having a molecular weight of 10,000 or more, and conductive particles as essential components. In addition, the film-like circuit connection material is melted and flowed by heating and pressurization and light irradiation, and the first connection terminal and the second connection terminal are connected under the condition that conduction between the circuit members by the conductive particles is ensured. After the primary connection for electrical connection is made, heating and pressurization and light irradiation are interrupted, and after a certain period of time due to a continuity test or the like, sufficient curing is performed again only by light irradiation.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, as a circuit member, a chip component such as a semiconductor chip, a resistor chip or a capacitor chip, a substrate such as a printed circuit board, a liquid crystal panel or the like is used. These circuit members are usually provided with a large number of connection terminals (or a single connection terminal in some cases), and at least one of the circuit members having light transparency is provided on those circuit members. At least one part of the connection terminals is arranged oppositely, an adhesive is interposed between the oppositely arranged connection terminals, and the connection terminals arranged opposite to each other by heating and pressurizing and irradiating light are electrically connected to form a connection body. At this time, the thickness of the light transmissive circuit member is preferably 1.2 mm or less in terms of light transmissive properties (Claim 7) . In addition, by making the form of the circuit connection material containing the photocurable resin into a film shape, the handling property is superior to the conventional paste-like circuit connection material, and the connection thickness can be made uniform. It is advantageous. Furthermore, in order to improve the adhesiveness with the circuit member, when heating is performed to such an extent that the curing reaction hardly proceeds and the resin flows, conduction between the connection terminal-conductive particle-connection terminal is performed by heating the connection material. It is possible to re-increase the melt viscosity of the connection material by introducing a cooling step after securing the above, whereby the pressure contact state of the conductive particles only by heating and cooling can be maintained and the resin can be fixed. This is not possible with a paste-like circuit connecting material.
[0008]
In the method shown in Claim 1 and Claim 2 , in the primary connection, the 1st connection terminal and the 2nd connection terminal are opposingly arranged, and the film-form circuit containing a photocuring component and electroconductive particle in the meantime The connecting material is interposed, and the first connecting terminal and the second connecting terminal arranged to face each other are electrically connected by heating and pressing and light irradiation or heating and pressing . Since the curing of the film-like circuit connection material is mainly carried out by photocuring, the role of the heating and pressurizing step is to melt and flow the adhesive so that the resin component around the part where the connection terminals and the conductive particles are in contact is sufficient. It can be considered that the conductive particles are sufficiently pressed between the connection terminals. For this reason, it may be heated to Tg of the adhesive or a temperature at which the flow of the adhesive necessary for sufficient deformation of the conductive particles can be obtained, and the temperature depends on the type of polymer resin that is a film forming material. The temperature is generally within the range of 80 to 140 ° C. This is lower than 150 to 190 ° C., which is a heating temperature necessary for connection of a film-like circuit connecting material using a conventional thermosetting resin as a curing component. Therefore, the connection temperature of the circuit member can be lowered by the above method. Moreover, when performing heat pressurization and light irradiation simultaneously, in order to fully contact an electroconductive particle by the flow of an adhesive agent, adjustment of melt fluidity and light irradiation capability is required. The light irradiation capability here depends on the light source of the light irradiation device to be used, and in the case of a light irradiation device using a light source with a small amount of light, the curing rate of the adhesive is slowed, Therefore, heating and pressurization and light irradiation can be performed at the same time (Claim 5 ). In the case of a light irradiation device using a light source with a large amount of light, an interval of 1 to several seconds is provided between the heating and pressurizing step and the light irradiation step in order to prioritize resin flow, and light is emitted after the start of heating and pressing. it is also possible to perform irradiation (claim 6). In this case, since the light irradiation is delayed, after the resin flows and the conduction of the connection terminal by the conductive particles is ensured, the amount of light may be increased to rapidly cure in a short time.
[0009]
By using a photocurable resin, a polymer resin having a molecular weight of 10,000 or more, and conductive particles as essential components, a film-like circuit connecting material capable of photocuring can be provided. This is due to the fact that most polymer resins having a molecular weight of 10,000 or more are solid at room temperature and have high film-forming ability. By mixing this polymer resin and photo-curing resin, it is possible to improve the handleability and make the connection thickness uniform, which is a disadvantage of conventional circuit connection materials using photo-curing resin. It is.
[0010]
A film-like circuit connecting material is melted and fluidized by heating and pressurization and light irradiation using a photocurable resin, a polymer resin having a molecular weight of 10,000 or more, and conductive particles as essential components. After the primary connection that electrically connects the first connection terminal and the second connection terminal under the condition that the conduction between the circuit members by the conductive particles is ensured, the heating and pressurization and the light irradiation are interrupted. and, after a certain period of time by conductivity test or the like, the method indicated in claim 1 for sufficient curing only by re-irradiation also, only by heat and pressure, the film-like circuit connecting material melt, flow, conductivity After the primary connection that electrically connects the first connection terminal and the second connection terminal under the condition that the conduction between the circuit members due to the conductive particles is ensured, the heating and pressurization is interrupted, and the continuity inspection is performed. A certain amount of time After, in the method of the claims 2 to perform sufficient curing only by light irradiation, to ensure initial conduction deformation of the conductive particles is sufficient, and its state is maintained even after heating and pressing ends Therefore, it is only necessary to perform heating and pressurization and light irradiation which are at least necessary to ensure conduction. The heating and pressing conditions at this time are preferably conditions that can be heated to a temperature above the Tg of the adhesive as described above, or to a temperature at which the flow of the adhesive necessary for sufficient deformation of the conductive particles can be obtained. The temperature is preferably in the range of 80 to 140 ° C., although it depends on the type of polymer resin that is the film forming material. Moreover, although a pressure changes with the kind of circuit member, the conditions which do not have a bad influence on a circuit member and can deform | transform an electroconductive particle are preferable. When the primary connection is made, a continuity test is performed. As a result, if the initial resistance is high and continuity cannot be ensured, the circuit member is peeled off to repair the circuit, but the curing of the adhesive is still sufficiently advanced. Therefore, the adhesive can be removed with a general-purpose solvent in a very short time. On the contrary, the adhesive which is uncured as long as conduction is ensured may be sufficiently cured by light irradiation.
[0011]
Moreover, after performing primary connection, it cools to below Tg of a film-form circuit connection material, and pressurization and light irradiation or pressurization is interrupted after that, Claim 3 or Claim 4 characterized by the above-mentioned. In the method shown, since the heating and pressing head of the thermocompression bonding apparatus is cooled immediately before the pressure is released, even if the adhesive is completely uncured or the curing reaction has hardly progressed, the temperature of the adhesive is reduced by the cooling process. Decreases to Tg or less, and the melt viscosity also increases again. Therefore, the restoration of the conductive particles at the time of releasing the pressure is suppressed, and the connection thickness is maintained, so that conduction can be ensured. Conversely, when the adhesive is in the same state, when the cooling process is not performed, the adhesive temperature is Tg or more and the melt viscosity is low, so that the connection thickness increases when the pressure is released, and the circuit A large number of bubbles are generated between them, causing a decrease in adhesiveness. Further, since the conductive particles are restored by increasing the connection thickness and the contact area with the circuit is reduced, the initial resistance is remarkably increased, and conduction cannot be ensured.
[0012]
The film-like circuit connection material used in the present invention is composed of an adhesive component obtained by mixing a photopolymerizable resin with a solid polymer resin for imparting film formability, and conductive particles. By doing so, it is possible to improve the handleability when connecting circuit members.
[0013]
Photocurable resins used in the present invention include photopolymerizable oligomers such as epoxy acrylate oligomers, urethane acrylate oligomers, polyether acrylate oligomers, polyester acrylate oligomers, trimethylolpropane triacrylate, polyethylene glycol diacrylate, polyalkylene glycol diacrylate. , And photopolymerizable resins represented by acrylic esters such as photopolymerizable polyfunctional acrylate monomers such as pentaerythritol acrylate, and methacrylic esters similar to these, and these resins can be used alone or as needed Although they may be used in combination, it is preferable to add a urethane acrylate oligomer in order to suppress curing shrinkage of the cured adhesive and to give flexibility. Further, since the above-mentioned photopolymerizable oligomer has a high viscosity, it is preferable to blend a monomer such as a low-viscosity photopolymerizable polyfunctional acrylate monomer for viscosity adjustment.
[0014]
These photocurable resins are polymerized and cured using a photoinitiator. Photoinitiators used in the present invention include benzoin ethers such as benzoin ethyl ether and isopropyl benzoin ether, benzyl ketals such as benzyl and hydroxycyclohexyl phenyl ketone, ketones such as benzophenone and acetophenone and derivatives thereof, thioxanthones, biimidazoles and the like Sensitizers such as amines, sulfur compounds and phosphorus compounds may be added to these photoinitiators in any ratio as necessary. At this time, it is necessary to select an optimal photoinitiator according to the wavelength of the light source to be used, desired curing characteristics, and the like. In addition, these photo-curable resins and thermoplastic resins such as polyethylene, ethyl acetate, and polypropylene, and resins such as polyethersulfone, polyetherimide, and polyimide having high heat resistance, and thermosetting resins such as epoxy resins, or A phenoxy resin, an elastomer, etc. can be mixed and used.
[0015]
The light used for curing can be ultraviolet rays that are widely used in general, and can be generated by a mercury lamp, a metal halide lamp, an electrodeless lamp, or the like. Further, when a radical reaction is used as the curing reaction, oxygen acts as a reaction inhibitor, so the amount of oxygen in the light irradiation atmosphere affects the curing of the photocurable resin. Since this greatly depends on the type and concentration of the photocurable resin, photoinitiator, sensitizer, etc., it is necessary to examine in detail for each compounding system.
[0016]
As the conductive particles, there are metal particles such as Au, Ag, Ni, Cu, and solder, carbon, etc., and these and non-conductive glass, ceramics, plastics, etc. formed by coating the above-mentioned conductive layer. Good. In the case of using plastic as a core or hot-melt metal particles, it is preferable because it has deformability by heating and pressurization, so that the contact area with the electrode is increased at the time of connection and reliability is improved. The conductive particles are selectively used in a wide range of 0.1 to 30% by volume with respect to 100 volumes of the adhesive component. In order to prevent an adjacent circuit from being short-circuited by excessive conductive particles, the content is more preferably 0.2 to 15% by volume. The average particle size of the conductive particles at this time is preferably 1 to 15 μm, although it depends on the amount of the conductive particles added. The compression elastic modulus of the conductive particles is preferably in the range of 1000 to 10,000 MPa in order to suppress the recovery of particles due to the elasticity of the adhesive when heating and pressurization and light irradiation are interrupted.
[0017]
Examples of silane coupling agents include vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris- (βmethoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-aminopropyltri There are ethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, isopropyl triethoxysilane, etc., but γ-methacryloxypropyltrimethoxysilane is used to increase the reactivity with the photocurable resin. Is more preferable.
[0018]
【Example】
Example 1
40 g of phenoxy resin (trade name PKHA, manufactured by Union Carbide Co., Ltd.) by weight, toluene (boiling point 110.6 ° C., SP value 8.90) / ethyl acetate (boiling point 77.1 ° C., SP value 9.10) = It dissolved in 60g of 50/50 mixed solvents, and it was set as the solution of 40% of solid content. The photo-curing resin includes an epoxy acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name NK Oligo EA-1020) and an acrylate monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name NK Ester A-TMM-3L). It was used at a weight ratio of 3/1. Benzophenone is used as the photoinitiator, and 4,4′-bisdiethylaminobenzophenone (made by Hodogaya Chemical Co., Ltd., trade name EAB) is used as the sensitizer so that the photoinitiator / sensitizer = 5/1. Used in combination. A nickel layer having a thickness of 0.2 μm is provided on the surface of particles having polystyrene as a core, and a gold layer having a thickness of 0.02 μm is provided outside the nickel layer, and conductive particles having an average particle diameter of 5 μm and a specific gravity of 2.5. Was made. The phenoxy resin 50, the photocurable resin 50, the photoinitiator 5, and the sensitizer 1 are blended at a solid weight ratio, and 3% by volume of conductive particles are further dispersed and applied to a fluororesin film having a thickness of 80 μm. The film-like circuit connecting material having a thickness of 20 μm was obtained by hot air drying at 70 ° C. for 10 minutes. A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a thin layer of 0.2 μm of indium oxide (ITO) using the film-like circuit connecting material obtained by the above manufacturing method The glass (thickness 1.1 mm, surface resistance 20 Ω / □) formed by using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.) as shown in FIG. At 20 ° C., heating and pressurization at 2 MPa for 20 seconds and ultraviolet irradiation from the ITO glass side were simultaneously performed to connect over a width of 2 mm, and after a lapse of time, the pressure was released to prepare a connection body. The amount of ultraviolet rays irradiated to the adhesive (hereinafter referred to as ultraviolet irradiation amount) was 1.3 J / cm <2>. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body.
[0019]
Example 2
Using the film-like circuit connecting material obtained in Example 1, a flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a 0.2 μm indium oxide (ITO) thin film The glass (thickness 1.1 mm, surface resistance 20 Ω / □) on which the layer is formed, using a pulse heat type thermocompression bonding apparatus (manufactured by Nippon Avionics Co., Ltd.), as shown in FIG. After heating and pressurizing and connecting over a width of 2 mm, the heating head was cooled to about 50 ° C. with air, then the pressure was released, and this was terminated. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body. The connection body obtained by the above method was irradiated with ultraviolet rays from the ITO glass side as shown in FIG. 3 using an ultraviolet irradiation device (USHIO INC.) To produce a connection body. The amount of UV irradiation at this time was 1.3 J / cm 2.
[0020]
Example 3
Using the film-like circuit connecting material obtained in Example 1, a flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a 0.2 μm indium oxide (ITO) thin film As shown in FIG. 1, the glass (thickness 1.1 mm, surface resistance 20Ω / □) on which the layer is formed is used by using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.). Simultaneous heating and pressurization at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation from the ITO glass side were performed to connect over a width of 2 mm, and after a lapse of time, the pressure was released to prepare a connection body. The amount of ultraviolet irradiation was 1.3 mJ / cm2. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body. After the connection by the above method, conduct a continuity test such as initial connection resistance, and after the test, simultaneously perform heating and pressurization at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation with an irradiation amount of 1.3 J / cm 2 using the same device, After a lapse of time, the pressure was released to prepare a connection body. After the connection by the above method, conduct a continuity test such as initial connection resistance, and after the test, simultaneously perform heating and pressurization at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation with an irradiation amount of 1.3 J / cm 2 using the same device, After a lapse of time, the pressure was released to prepare a connection body.
[0021]
Example 4
Using the film-like circuit connecting material obtained in Example 1, a flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a 0.2 μm indium oxide (ITO) thin film As shown in FIG. 1, the glass (thickness 1.1 mm, surface resistance 20Ω / □) on which the layer is formed is used by using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.). Simultaneous heating and pressurization at 130 ° C. and 2 MPa for 3 seconds and UV irradiation from the ITO glass side were performed to connect over a width of 2 mm, and after a lapse of time, the pressure was released to prepare a connection body. The amount of ultraviolet irradiation was 1.3 J / cm2. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body. As a result of conducting a continuity test of the initial connection resistance and the like after the connection by the above method, it was confirmed that there was a continuity failure. Therefore, the circuit was repaired after the test was completed, and the same apparatus was used as in the first embodiment. At 20 ° C. for 20 seconds at 20 ° C. and ultraviolet irradiation with an irradiation amount of 1.3 J / cm 2 were simultaneously performed, and after a lapse of time, the pressure was released to prepare a connection body.
[0022]
Example 5
Using the film-like circuit connecting material obtained in Example 1, a flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a 0.2 μm indium oxide (ITO) thin film As shown in FIG. 1, the glass (thickness 1.1 mm, surface resistance 20Ω / □) on which the layer is formed is used by using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.). Simultaneous heating and pressurization at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation from the ITO glass side were performed to connect over a width of 2 mm, and after a lapse of time, the pressure was released to prepare a connection body. The amount of ultraviolet irradiation was 5.0 J / cm2. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body. At the time of connection for 10 seconds in FIG. 1, only heating and pressurization was started, and after 2 seconds had elapsed, ultraviolet irradiation was started for 8 seconds, and two steps were completed simultaneously after 10 seconds of heating and pressurization.
[0023]
Example 6
Example 1 except that the conductive particles of the film-like circuit connecting material used in Example 1 were replaced with nickel particles having an average particle diameter of 5 μm (trade name DSP3101, specific gravity 8.5, manufactured by Daido Special Tuna Co., Ltd.). A connected body was produced in the same manner as described above.
[0024]
Example 7
The photocurable resin of the film-like circuit connecting material used in Example 1 was replaced with a urethane acrylate oligomer (trade name NK Oligo UA-512, manufactured by Shin-Nakamura Chemical Co., Ltd.) and an acrylate monomer (A-TMM-3L). Otherwise, a connection body was fabricated in the same manner as in Example 1.
[0025]
Comparative Example 1
A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm and a thin film of 0.2 μm of indium oxide (ITO) using the film-like circuit connecting material used in Example 1. The layered glass (thickness 1.1 mm, surface resistance 20 Ω / □) was heated and pressed at 130 ° C. and 2 MPa for 20 seconds using a constant heat type thermocompression bonding apparatus (manufactured by our company), and connected over a width of 2 mm. After the passage of time, the pressure was released and this was terminated. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body. Using the ultraviolet irradiation apparatus used in Example 2, the connection body obtained by the above method was irradiated with ultraviolet rays from the ITO glass side as shown in FIG. 3 to produce a connection body. The amount of UV irradiation at this time was 1.3 J / cm 2.
[0026]
Comparative Example 2
A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm and a thin film of 0.2 μm of indium oxide (ITO) using the film-like circuit connecting material used in Example 1. As shown in FIG. 1, the glass (thickness 1.1 mm, surface resistance 20Ω / □) on which the layer is formed is used by using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.). Simultaneous heating and pressurization at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation from the ITO glass side were performed to connect over a width of 2 mm, and after a lapse of time, the pressure was released to prepare a connection body. The amount of ultraviolet irradiation was 5.0 J / cm2. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body.
[0027]
Comparative Example 3
Phenoxy resin 50 containing a phenoxy resin, which is a compounded resin of the film-like circuit connecting materials used in Examples 1 to 6 and Comparative Examples 1 and 2, and a liquid epoxy resin containing a microcapsule-type latent curing agent, in a solid weight ratio. In addition, the liquid epoxy resin 50 was blended, and the conductive particles used in Example 1 were mixed and dispersed by 3% by volume, and applied to a fluororesin film having a thickness of 80 μm using a coating apparatus. A film-like circuit connecting material having an adhesive layer thickness of 20 μm was obtained by drying with hot air for a minute. A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a thin layer of 0.2 μm of indium oxide (ITO) using the film-like circuit connecting material obtained by the above manufacturing method The glass (thickness 1.1 mm, surface resistance 20 Ω / □) formed was connected to a 2 mm width by heating and pressing at 130 ° C. and 2 MPa for 20 seconds using a constant heat type thermocompression bonding apparatus (manufactured by our company). After the elapse of time, the pressure was released, and this was terminated. At this time, after adhering the adhesive surface of the film-like circuit connecting material on the ITO glass in advance, the film is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. It connected with FPC which is one to-be-adhered body.
[0028]
Comparative Example 4
The photo-curing resin includes an epoxy acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name NK Oligo EA-1020) and an acrylate monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name NK Ester A-TMM-3L). It was used at a weight ratio of 3/1, benzophenone was used as the photoinitiator, and 4,4′-bisdiethylaminobenzophenone (made by Hodogaya Chemical Co., Ltd., trade name EAB) was used as the sensitizer. It was used by mixing so that sensitizer = 5/1. In addition, a nickel layer having a thickness of 0.2 μm is provided on the surface of particles having polystyrene as a nucleus, and a gold layer having a thickness of 0.02 μm is provided outside the nickel layer, and a conductive material having an average particle diameter of 5 μm and a specific gravity of 2.5. Particles were prepared. Using these, they were blended so as to be a photocurable resin 100, a photoinitiator 5 and a sensitizer 1 in a solid weight ratio, and further 3% by volume of conductive particles were dispersed and dispersed to obtain a paste-like circuit connection material. . A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a thin layer of 0.2 μm indium oxide (ITO) using the paste-like circuit connecting material obtained by the above manufacturing method Glass (thickness 1.1 mm, surface resistance 20 Ω / □) is connected to a width of 2 mm by heating and pressing at 130 ° C. and 2 MPa for 20 seconds using a pulse heat type thermocompression bonding apparatus (manufactured by Nippon Avionics Co., Ltd.). Then, the pressure was released after a lapse of time, and this was terminated. At this time, an appropriate amount of paste-like circuit connecting material was applied in advance on ITO glass and connected to the other adherend FPC. The connection body obtained by the above method was irradiated with ultraviolet rays from the ITO glass side as shown in FIG. 3 using an ultraviolet irradiation device (USHIO INC.) To produce a connection body. The amount of UV irradiation at this time was 1.3 J / cm 2.
[0029]
The initial resistance, adhesiveness, and circuit repairability of the connectors obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were evaluated. Regarding the initial resistance, after connecting the circuit members, the resistance value between adjacent circuits of the FPC including the connection portion was measured with a multimeter. The measurement current was 1 mA, and the resistance value was shown as an average (x + 3σ) of 150 resistances between adjacent circuits. About the adhesiveness with respect to FPC and ITO glass, the adhesive force was measured and evaluated by the 90 degree | times peeling method according to JIS-Z0237. As a measuring device, Tensilon UTM-4 (peeling speed 50 mm / min, 25 ° C.) manufactured by Toyo Baldwin Co., Ltd. was used. For circuit repairability, the FPC of the connection part was peeled off from the ITO glass, and a certain area (20 × 2 mm) of the adhesive remaining on the ITO glass was wiped off with a cotton swab impregnated with acetone, which was required to finish. Evaluated by time.
[0030]
These results are shown in Table 1 of FIG. 4 for all examples and comparative examples. In Example 1 in which heating and pressurization and ultraviolet irradiation were performed simultaneously, both initial resistance and adhesive strength showed good values. In Example 2 in which heating and pressurization and ultraviolet irradiation are not performed at the same time and the connection body is sufficiently cooled before the pressure is released, an increase in the connection thickness is suppressed, resulting in a low connection resistance. ing. Further, in the case of Example 3, which is a connection in a shorter time than Example 1 and Example 2 of 10 seconds, the recovery of the conductive particles is suppressed because the curing reaction of the adhesive is relatively advanced. There was no problem with the connection resistance, but as a result of performing ultraviolet irradiation to further promote the curing reaction, a good value was also obtained for the adhesive strength. In the case of Example 4, since heating and pressurization and ultraviolet irradiation were performed only for 3 seconds, the deformation and curing reaction of the conductive particles were insufficient, and the initial resistance was high. Therefore, when the FPC was peeled off and the circuit was repaired, the adhesive was uncured, so that the repair could be performed in a very short time. This makes it possible to quickly reconnect the circuits. Further, in the case of Example 5 in which the ultraviolet irradiation amount was increased to 5.0 J / cm 2, good connection characteristics were obtained as a result of delaying the light irradiation start by 2 seconds in order to prioritize ensuring the flow and conduction of the resin. . In Example 6 and Example 7 in which the conductive particles and the photocurable resin are replaced, the connection state is good. On the other hand, in the case of Comparative Example 1 which is a connection method not provided with a cooling process, the adhesive strength is sufficiently equal to that of Examples 1 to 4 because the adhesive is sufficiently cured by ultraviolet irradiation. However, since the adhesive is not fixed because there is no cooling step, the deformation of the conductive particles is not maintained, and the contact area with the circuit member is reduced, so that the initial resistance is remarkably high. Moreover, in Comparative Example 2 in which heating and pressurization and ultraviolet irradiation were simultaneously performed under the condition of a light irradiation amount of 5.0 J / cm 2 with respect to Example 5, the curing reaction of the adhesive proceeds faster than the flow of the resin. Therefore, the conductive particles are not sufficiently in contact with the circuit member, resulting in poor conduction. Further, in Comparative Example 3 using an adhesive mainly composed of a thermosetting resin, the reaction rate of the adhesive is low under the connection conditions of 130 ° C., 2 MPa, and 20 seconds, so that sufficient curing cannot be obtained. The adhesive force was considerably reduced and the initial resistance was also increased. In the case of Comparative Example 4, since the polymer resin imparting film-forming property is not contained, the primary is compared with Example 2 in which conduction is ensured when the film-like circuit connecting material is used. It was inferior in terms of ensuring conduction during the cooling process in connection, and was also disadvantageous compared to a film-like material in terms of handleability.
[0031]
【The invention's effect】
According to the present invention, a film-like circuit connection material containing a photocurable resin and conductive particles as essential components is interposed in an adhesive, and circuit members are connected by light irradiation simultaneously with heating or pressurization. Therefore, it is possible to lower the temperature required for connection than before, and after connecting the heat and pressure, the connection body is cooled immediately before releasing the pressure. Adhesive strength and good electrical continuity can be obtained. Furthermore, when a connection failure occurs during the initial connection, the resin curing reaction has not progressed so much, so that circuit repair with a general-purpose solvent can be easily performed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a connection method (Example) using a film-like circuit connection material of the present invention.
FIG. 2 is a cross-sectional view illustrating a connection method (Example) using the film-like circuit connection material of the present invention.
FIG. 3 is a cross-sectional view illustrating a connection method (comparative example) using a film-like circuit connection material.
FIG. 4 is a table showing evaluation results for initial resistance, adhesiveness, and circuit repairability of the connectors obtained in Examples 1 to 7 and Comparative Examples 1 to 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... ITO glass 2 ... Conductive particle 3 ... FPC circuit 4 ... FPC base material 5 ... Adhesive 6 ... Light source 7 ... Light 8 ... Base 9 ... Heating and pressing head 10 ... Air inlet for cooling

Claims

Two circuit members, at least one of which is light transmissive, that is, a first circuit member having a first connection terminal and a second circuit member having a second connection terminal are connected to the first connection terminal and the second circuit member. Two connection terminals are arranged opposite to each other, and a film-like circuit connection material containing a photocuring component and conductive particles is interposed between the first and second connection terminals arranged opposite to each other, and heated. The first connection terminal and the second connection terminal are electrically connected under such conditions that the film-like circuit connection material melts and flows by pressurization and light irradiation, and electrical conduction between the circuit members is ensured. An electrode connection method in which heating and pressurization and light irradiation are interrupted after the primary connection to be connected, and sufficient curing is performed again by light irradiation after a lapse of a predetermined time by a continuity test.

Two circuit members at least one of which is light transmissive, that is, a first circuit member having a first connection terminal and a second circuit member having a second connection terminal are connected to the first connection terminal and the second circuit member. Two connection terminals are arranged opposite to each other, and a film-like circuit connection material containing a photocuring component and conductive particles is interposed between the first and second connection terminals arranged opposite to each other, and heated. Primary that electrically connects the first connection terminal and the second connection terminal under such conditions that the film-like circuit connection material melts and flows by pressurization, and electrical conduction between the circuit members is ensured. An electrode connection method in which heating and pressurization is interrupted after connection is made, and sufficient curing is performed by light irradiation after a lapse of a certain time by continuity inspection.

The electrode connection method according to claim 1, wherein after the primary connection is made, the film-like circuit connection material is cooled to a glass transition point or less, and then pressurization and light irradiation are interrupted.

The electrode connection method according to claim 2, wherein after the primary connection is performed, cooling is performed to a temperature equal to or lower than the glass transition point of the film-like circuit connection material, and then pressurization is interrupted.

The electrode connection method according to claim 1, wherein heating and pressurization and light irradiation are started simultaneously.

The electrode connection method according to claim 1, wherein an interval of 1 to several seconds is provided between heating and pressurization and light irradiation, and light irradiation is performed after the start of heating and pressurization.

The electrode connection method according to claim 1, wherein the thickness of the circuit member having optical transparency is 1.2 mm or less.

The electrode connection method according to claim 1, wherein the conductive particles have a compressive elastic modulus of 1000 to 10,000 MPa.