JP4075323B2

JP4075323B2 - Circuit board bonding method

Info

Publication number: JP4075323B2
Application number: JP2001131519A
Authority: JP
Inventors: 義高藤田; 康嗣正木
Original assignee: Casio Computer Co Ltd
Current assignee: Casio Computer Co Ltd
Priority date: 2001-04-27
Filing date: 2001-04-27
Publication date: 2008-04-16
Anticipated expiration: 2021-04-27
Also published as: JP2002329958A

Abstract

PROBLEM TO BE SOLVED: To provide a method of joining circuit boards which exactly conductively connects terminals by preventing the misregistration between terminal rows due to the difference of the thermal expansion coefficients of the two circuit boards to be joined together, thereby accurately opposing the corresponding terminals in both terminal rows to each other. SOLUTION: At a room temperature, the arrangement pitch P1 of the connector terminals 44 of a base film 43 is smaller by a specified quantity than the arrangement pitch P2. Then, in order to join them, first the base film 43 is elongated by preheating, and the arrangement pitch of the connector terminals 44 is made the same as the arrangement pitch of input terminals 35. Next, they are registered so that the corresponding connector terminals 44 of the base film 43 and the input terminal 35 of the glass board 33 oppose to each other. When joining them together through an anisotropic conductive adhesive 36 by regular pressurized heating after this, each terminal row of both the base film 43 and the glass board 33 is elongated by the same quantity. As a result, no matter where the origin of the elongation of the base film 43 and the glass board 33 at this regular pressurized heating are, the misregistration is not made to occur in the terminal rows.

Description

【０００１】
【発明の属する技術分野】
この発明は回路基板の接合方法に関し、詳細には、接合すべき２つの回路基板の熱膨張率の違いによる端子列の位置ずれを防止できる回路基板の接合方法に関する。
【０００２】
【従来の技術】
例えば液晶表示装置の製造方法では、液晶表示パネルの一方の回路基板とフレキシブル回路基板とをその間に異方性導電接着剤等のコネクタ部材を介して熱圧着接合する方法がよく用いられる。
【０００３】
図９はこのような回路基板の接合方法で用いられている従来の回路基板の接合装置の一例の一部の斜視図を示したものである。この接合装置は、吸着機構（図示せず）付きの固定台１、固定台１の横にＸ、Ｙ方向(水平方向)へ移動可能に配置された吸着機構（図示せず）付きの可動台２、固定台１の上方に上下方向移動可能に配置されボンディングツール３等を備えている。
【０００４】
固定台１上には、液晶表示パネル４が位置決めされて吸着配置されるようになっている。液晶表示パネル４は、上ガラス基板５と下ガラス基板６とがほぼ方形枠状のシール材（図示せず）を介して貼り合わされ、シール材の内側における両ガラス基板５、６間に液晶（図示せず）が封入され、上ガラス基板５の上面に上偏光板７が貼り付けられ、下ガラス基板６の下面に下偏光板（図示せず）が貼り付けられたものからなっている。この場合、下ガラス基板６の所定の１辺部は上ガラス基板５から突出され、該突出部６ａ上にはＩＴＯ等の透明な金属からなる複数の入力端子８（図１０参照）が設けられ、入力端子８上には帯状の異方性導電接着剤９が仮圧着されて配置されている。異方性導電接着剤９は、図１０に示すように、熱硬化性樹脂１０中に多数の導電性粒子１１を含有させたものからなっている。
【０００５】
可動台２上には、フレキシブル回路基板１２が位置決めされて吸着配置されるようになっている。フレキシブル回路基板１２は、ポリイミド等からなるベースフィルム１３の上面中央部に液晶表示パネル駆動用のＬＳＩ等からなる半導体チップ１４がＣＯＦ(chip on film)方式で搭載され、ベースフィルム１３の一端部下面に銅等からなる複数の接続端子１５（図１０参照）が半導体チップ１４に接続されて設けられたものからなっている。
【０００６】
次に、この接合装置でフレキシブル回路基板１２の一端部に配列された端子部を液晶表示パネル４の下ガラス基板６の突出部６ａ上の端子配列部に接合する場合について説明する。まず、固定台１上に液晶表示パネル４を所定の位置に位置決めして吸着配置する。この場合、下ガラス基板６の突出部６ａ上には帯状の異方性導電接着剤９が配置されている。また、可動台２上にフレキシブル回路基板１２を所定の位置に位置決めして吸着配置する。この状態では、フレキシブル回路基板１２の一端部は可動台２から所定の量だけ突出され、異方性導電接着剤９上に位置させられている。
【０００７】
次に、この状態において、図示していないが、フレキシブル回路基板１２の一端部および下ガラス基板６の突出部６ａの各Ｘ、Ｙ方向位置をそれぞれカメラ等を備えた画像処理位置検出装置により検出する。そして、この検出結果に基づいて、可動台２をＸ、Ｙ方向に適宜に移動させ、フレキシブル回路基板１２の一端部の下ガラス基板６の突出部６ａに対する位置合わせを行う。次に、ボンディングツール３を下降させ、その下面により、フレキシブル回路基板１２の一端部下面を下ガラス基板６の突出部６ａ上の異方性導電接着剤９の上面に圧接させる。そして、ボンディングツール３による加熱加圧により、フレキシブル回路基板１２の一端部下面を液晶表示パネル４の突出部６ａ上の適正位置に異方性導電接着剤９を介して接合し、夫々の各端子を異方性導電接着剤９中の導電性粒子を介して導電接続する。
【０００８】
この理想的な接合状態を図１０に示す。ただし、図１０では、図示の都合上、接続端子１５および入力端子８はそれぞれ多数個ある中の３個しか図示していない。この理想接合状態は、ベースフィルム１３の熱膨張率が液晶表示パネル４の下ガラス基板６の熱膨張率と等しい場合に得られるものであり、接続端子１５の配列ピッチと入力端子８の配列ピッチは同じであり、互いに対向する接続端子１５と入力端子８とはその間に介在されて適宜に弾性変形した導電性粒子１１を介して導電接続されている。また、接続端子１５を含むフレキシブル回路基板１２の一端部下面と入力端子８を含む下ガラス基板６の突出部６ａ上面とは熱硬化性樹脂１０を介して接着されている。
【０００９】
ところで、フレキシブル回路基板１２のポリイミド等からなるベースフィルム１３の熱膨張率が液晶表示パネル４の下ガラス基板６の熱膨張率よりも大きいため、接合時におけるボンディングツール３の加熱温度が通常２００〜３００℃程度の高温となることにより、ベースフィルム１３の接続端子１５を含む部分のＸ方向への伸び量（以下、単に、伸び量という）が下ガラス基板６の突出部６ａの入力端子８を含む部分のＸ方向への伸び量（以下、単に、伸び量という）よりも大きくなってしまう。すなわち、図１１に示すように、ベースフィルム１３および下ガラス基板６の各温度は、接合開始前は共に室温であり、接合が開始されて加熱されても共にほぼ同じように上昇し、接合終了時点では、ベースフィルム１３の温度は接合温度Ｔ１となり、下ガラス基板６の温度はベースフィルム１３の接合温度Ｔ１よりもやや低い接合温度Ｔ２となる。しかし、図１２に示すように、接合終了時点においては、ベースフィルム１３の伸び量Ｌ１は下ガラス基板６の伸び量Ｌ２よりも相当に大きくなってしまう。伸び量Ｌ１、Ｌ２の定義については、後で説明する。
【００１０】
そこで、これらの伸び量Ｌ１、Ｌ２の差（Ｌ１−Ｌ２）を考慮して、接合前の初期の状態においては、図１３に示すように、フレキシブル回路基板１２の接続端子１５の配列ピッチＰ１を下ガラス基板６の突出部６ａの入力端子８の配列ピッチＰ２よりも上記伸び量の差（Ｌ１−Ｌ２）が相殺されるように所定量だけ小さくしている。ここで、伸び量Ｌ１、Ｌ２とは、各端子１５、８の配列ピッチＰ１、Ｐ２のそれぞれの合計値の各増加量のことであり、つまり図１３に示す左右両端の各端子１５ａ、１５ｂおよび８ａ、８ｂの各幅方向中心間の長さの増加量のことである。
【００１１】
【発明が解決しようとする課題】
ところで、上記従来の接合方法では、フレキシブル回路基板１２の一端部の下ガラス基板６の突出部６ａに対する位置合わせを行っているだけであり、ベースフィルム１３および下ガラス基板６の接合時の加熱による伸びの基点を制御することは困難である。この伸びの基点位置はヒータチップの当接具合等によって微妙に変ってくるものであり、ベースフィルム１３および下ガラス基板６の接合時の加熱による伸びの基点が図１３においてＡ−Ａ線で示すように左右方向の中心である場合には、ベースフィルム１３および下ガラス基板６がそれぞれ左右方向に均等に伸びることにより、図１０に示すように、接続端子１５の配置位置と入力端子８の配置位置とをほぼ同じとすることができる。しかし、ベースフィルム１３および下ガラス基板６の接合時の加熱による伸びの基点が例えば図１３においてＢ−Ｂ線で示すように右端部である場合には、ベースフィルム１３および下ガラス基板６が共にほとんど左方向へのみ伸びることにより、図１４に示すように、接続端子１５の配置位置と入力端子８の配置位置とがずれてしまう。この結果、接続端子１５と入力端子８との対向面積が減少し、その間に介在される導電性粒子１１の個数が減少し、接続抵抗が高くなってしまうという問題があった。特に、接続端子１５および入力端子８の配列ピッチの微細化を行う場合には、大きな支障となってしまう。
この発明の目的は、接合すべき２つの回路基板の熱膨張率の違いによるそれぞれ端子列間の位置ずれを防止し、双方の端子列の対応する各端子同士を正確に対向させて確実に導電接続する回路基板の接合方法を提供することである。
【００１２】
【課題を解決するための手段】
本発明の回路基板の接合方法は、請求項１に記載のように、複数の端子が配列された第１の端子列を備える第１の回路基板と前記第１の端子列の各端子に対応する複数の端子が配列された第２の端子列を備える第２の回路基板とを、それぞれの前記第１の端子列と前記第２の端子列を対向させて、熱硬化性樹脂中に導電性粒子を含有させた異方性導電接着剤からなるコネクタ部材により接合し、前記第１の端子列と前記第２の端子列との対応する端子とを前記コネクタ部材を介して導電接続する回路基板の接合方法において、前記第１の端子列と前記第２の端子列の配列ピッチを予め異ならせて形成した前記第１、第２の回路基板のうち少なくとも一方の回路基板と前記コネクタ部材とを、前記熱硬化性樹脂がその中に含有する前記導電性粒子の流動を抑制できる程度に硬化させ、且つ前記第１の端子列と前記第２の端子列の各端子配列ピッチが同一となる温度に予備加熱する予備工程と、前記予備工程の後、前記第１の回路基板と前記第２の回路基板とを前記第１の端子列と前記第２の端子列のそれぞれの対応する端子同士が対向するように位置合せする位置決め工程と、前記位置決め工程の後、前記第１の回路基板と前記第２の回路基板とを、その間に前記コネクタ部材を介在させてさらに加熱しつつ加圧し、前記第１の端子列と前記第２の端子列を接合する接合工程とを具備することを特徴とするものである。
この請求項１に記載の発明によれば、接合する前に両回路基板のうち少なくとも一方の回路基板と前記コネクタ部材とを、前記熱硬化性樹脂がその中に含有する前記導電性粒子の流動を抑制できる程度に硬化させ、且つ前記第１の端子列と前記第２の端子列の各端子配列ピッチが同一となる温度まで予備加熱した後、対応する各端子同士が対向するように位置合せするので、この後の接合工程における接合すべき２つの回路基板の熱膨張率の違いや伸びの基点の違いによる端子列の位置ずれを防止し、端子列同士を常に対応する端子同士を正確に対向させて確実に導電接続することができる。
本発明においては、請求項２に記載のように、前記予備工程終了時点における前記第１の回路基板と前記第２の回路基板の各温度は、前記接合工程における前記第１の端子列と前記第２の端子列の各伸び量が等しくなる温度に設定される。
そして、請求項３に記載のように、本発明は、前記第１の回路基板の方が前記第２の回路基板より熱膨張率が大きく、予備工程前の状態で前記第１の端子列より前記第２の端子列の方が端子ピッチが大きい回路基板同士の接合に好適である。
また、本発明は、請求項４に記載のように、前記第１の回路基板は液晶表示パネルの一方の回路基板であり、前記第２の回路基板はフレキシブル回路基板である回路基板同士の接合に好適である。
本願のもう一つの発明の回路基板の接合方法は、請求項５に記載のように、第１の回路基板の第１の端子列を形成する複数の第１の端子と、第２の回路基板に前記第１の端子にそれぞれ対応して配列され第２の端子列形成する第２の端子とを、熱硬化性の絶縁性樹脂中に導電性粒子を含有させてなる異方性導電接着剤を介して電気的に接合する回路基板の接合方法において、配列ピッチを予め異ならして形成した第１の端子列と第２の端子列がそれぞれに形成された前記第１、第２の回路基板のうち一方の回路基板と共に前記異方性導電接着剤を、前記導電性粒子の流動が抑制される程度の硬さに硬化させ、且つ前記第１の端子列と前記第２の端子列の各端子配列ピッチが同一となる温度に加熱する予備工程と、前記予備工程終了後、前記第１の回路基板と前記第２の回路基板とをその間に前記異方性導電接着剤を挟んで加熱しつつ加圧し、前記絶縁性樹脂を前記予備工程で硬化させた状態よりも更に硬化させ、前記第１の端子列と前記第２の端子列とを前記導電性粒子を介して導電接続する接合工程とを具備することを特徴とするものである。
【００１３】
【発明の実施の形態】
図１はこの発明の一実施形態としての回路基板の接合装置の要部の斜視図を示したものである。この接合装置は、吸着機構（図示せず）付きの固定台２１を備えている。固定台２１の上方にはボンディングツール２２が配置されている。ボンディングツール２２はヒータチップ２３を備え、吸着機構（図示せず）付きの支持板２４の下面の一方側に取り付けられている。ヒータチップ２３を含むボンディングツール２２は、複数の加熱温度設定が瞬時に行える加熱温度制御機能を備えている。支持板２４の下面の他方側の４角には吸着脚２５が設けられている。吸着脚２５の下面は、吸着機構の作用により、大気圧よりも低い圧力面となるようになっている。吸着脚２５の下面の高さ位置はボンディングツール２２の下面の高さ位置とほぼ同じ位置となっている。そして、ヒータチップ２３、支持板２４および吸着脚２５は、一体となって、Ｘ、Ｙ、Ｚ方向(位置決め用)およびＸＹ平面内での回転角θ(姿勢調整用)方向に移動されるようになっている。
【００１４】
固定台２１上には、液晶表示パネル３１がＸ、Ｙ、θ方向に位置決めされて吸着配置されるようになっている。液晶表示パネル３１は、上ガラス基板３２と下ガラス基板３３とがほぼ方形枠状のシール材（図示せず）を介して貼り合わされ、シール材の内側における両ガラス基板３２、３３間に液晶（図示せず）が封入され、上ガラス基板３２の上面に上偏光板３４が貼り付けられ、下ガラス基板３３の下面に下偏光板（図示せず）が貼り付けられたものからなっている。この場合、下ガラス基板３３の所定の１辺部は上ガラス基板３２から突出され、該突出部３３ａ上にはＩＴＯ等の透明な金属からなる複数の入力端子３５（図２参照）が設けられ、入力端子３５上には帯状の異方性導電接着剤３６が仮圧着されて配置されるようになっている。異方性導電接着剤３６は、図２に示すように、熱硬化性樹脂３７中に多数の導電性粒子３８を含有させたものからなっている。
【００１５】
４つの吸着脚２５の下面には、フレキシブル回路基板４１がＸ、Ｙ、θ方向に位置決めされて吸着配置されるようになっている。フレキシブル回路基板４１は、ポリイミド等からなるベースフィルム４２の上面中央部に液晶表示パネル駆動用のＬＳＩ等からなる半導体チップ４３がＣＯＦ(chip on film)方式で搭載され、ベースフィルム４２の一端部下面に銅等からなる複数の接続端子４４（図２参照）が半導体チップ４３に接続されて設けられたものからなっている。
【００１６】
次に、この接合装置でフレキシブル回路基板４１の一端部を液晶表示パネル３１の下ガラス基板３３の突出部３３ａ上に接合する場合について説明する。まず、固定台２１上に液晶表示パネル３１をＸ、Ｙ、θ方向に位置と姿勢を決めて吸着配置する。この場合、下ガラス基板３３の突出部３３ａ上には帯状の異方性導電接着剤３６が仮圧着されて配置されている。また、４つの吸着脚２５の下面にフレキシブル回路基板４１をＸ、Ｙ、θ方向に位置決めして吸着配置する。この状態では、フレキシブル回路基板４１の接続端子４４が並設された一端部が熱圧着ヘッドとなるヒータチップ２３先端面に密接するように配置されている。なお、ヒーターチップ先端面にも吸着機能を持たせ、この先端面にフレキシブル回路基板４１の一端部を吸着させるようにしてもよい。
【００１７】
ここで、図１では、ボンディングツール２２が、固定台２１上に吸着配置された液晶表示パネル３１の突出部３３ａの上方に位置するように図示しているが、この時点では、ボンディングツール２２は上限位置においてＹ方向に移動されて固定台２１と対向しない待機位置に位置させられている。この状態におけるベースフィルム４２の接続端子４４と下ガラス基板３３の入力端子３５との関係を図２に示す。ただし、図２では、図示の都合上、接続端子４４および入力端子３５はそれぞれ多数個の内の３個しか図示していない。この図２に示す状態では、つまり接合前の初期の状態では、図６に示す本加熱加圧終了時点におけるベースフィルム４２の伸び量Ｌ１と下ガラス基板３３の伸び量Ｌ２との差（Ｌ１−Ｌ２）を考慮して、接続端子４４の配列ピッチＰ１は入力端子３５の配列ピッチＰ２よりも上記伸び量の差（Ｌ１−Ｌ２）が相殺されるように所定量だけ小さくなっている。
【００１８】
次に、ボンディングツール２２が待機位置に位置する状態において、ヒーターチップ２３を含むボンディングツール２２による予備加熱により、ベースフィルム４２の接続端子４４が並設された一端部を予め設定された予熱温度となるまで加熱する。すると、図５に示すように、下ガラス基板３３の温度は室温に保たれたままであるが、ベースフィルム４２の温度は上昇して予め設定された予熱温度Ｔ３となる。これにより、図６に示すように、下ガラス基板３３は伸びないが、ベースフィルム４２は予め設定された量Ｌ３だけ伸びる。ここで、ベースフィルム４２の伸び量Ｌ３を、図２に示す入力端子３５の配列ピッチＰ２と接続端子４４の配列ピッチＰ１との差（Ｐ２−Ｐ１）の合計値となるように予め設定しておくと、図３に示すように、接続端子４４の配列ピッチＰ３は入力端子３５の配列ピッチＰ２と等しくなる。
【００１９】
次に、この状態において、図示していないが、フレキシブル回路基板４１の一端部および下ガラス基板３３の突出部３３ａの各Ｘ、Ｙ方向位置をそれぞれカメラ等を備えた画像処理位置検出装置により検出する。そして、この検出結果に基づいて、待機位置に位置するボンディングツール２２をＸ、Ｙ方向に適宜に移動させ、フレキシブル回路基板４１の一端部の下ガラス基板３３の突出部３３ａに対する位置合わせを行い、フレキシブル回路基板４１の接続端子４４を対応する入力端子３５の上方の整合位置に正確に位置させる。
【００２０】
次に、ボンディングツール２２をＺ方向に所定量だけ下降させ、フレキシブル回路基板４１の一端部下面を下ガラス基板３３の突出部３３ａ上の異方性導電接着剤３６の上面に圧接させる。そして、ヒーターチップ２３を発熱させ本加熱温度にまでボンディングツール２２を加熱して本加熱加圧を行う。、この本加熱加圧により、図５に示すように、、ベースフィルム４２の温度が予熱温度Ｔ３からさらに上昇して本加熱加圧終了時点で予定の接合温度Ｔ１となると同時に、下ガラス基板３３の温度が室温から上昇して本加熱加圧終了時点で予定した接合温度Ｔ２となる。これにより、図６に示すように、ベースフィルム４２はさらに（Ｌ１−Ｌ３）だけ伸びて当初からの伸び量が所期の伸び量Ｌ１となり、下ガラス基板３３は所期の量Ｌ２だけ伸びる。ここで、Ｌ２＝（Ｌ１−Ｌ３）となるように予め予備加熱温度Ｔ３を設定しておくことにより、本加熱加圧時におけるベースフィルム４２の一端部の伸び量と下ガラス基板３３の突出部３３ａの伸び量とは同じとなる。
【００２１】
この結果、ベースフィルム１３および下ガラス基板６の伸びの基点が図３においてＡ−Ａ線で示すように左右方向の中心であっても、Ｂ−Ｂ線で示すように右端部であっても、つまりどこであっても、図４に示すように、接続端子４４の配列ピッチと入力端子３５の配列ピッチとが等しく拡大され、接続端子４４が対応する入力端子３５に正確に対向して重畳した配置となる。そして、この状態では、互いに対向する接続端子４４と入力端子３５とはその間に介在されて適宜に弾性変形した導電性粒子３８を介して確実に導電接続されている。また、接続端子４４を含むフレキシブル回路基板４１の一端部下面と入力端子３５を含む下ガラス基板３３の突出部３３ａ上面とは熱硬化性樹脂３７を介して接着されている。
【００２２】
以上のように、この接合方法では、本加熱加圧前にフレキシブル回路基板４１を予備加熱してその接続端子間のピッチを接合すべき入力端子間のピッチと同一にすると共に位置合わせをした後に本加熱加圧を行い、その本加熱加圧におけるフレキシブル回路基板４１の一端部の伸び量（Ｌ１−Ｌ３）と下ガラス基板３３の突出部３３ａの伸び量Ｌ２が等しくなるように、フレキシブル回路基板４１の一端部の予熱温度Ｔ３を設定したから、接合すべきベースフィルム４２と下ガラス基板３３の熱膨張率の違いおよび伸びの基点の相違による端子列の位置ずれが防止され、端子列同士を常に確実に所期の通り導電接続することができる。
【００２３】
なお、上記実施形態では、ベースフィルム４２のみを予備加熱する場合について説明したが、これら限らず、ベースフィルム４２をボンディングツール２２で予備加熱するとともに、下ガラス基板３３を加熱手段（図示せず）を備えた固定台２１で予備加熱するようにしてもよい。次に、この場合におけるベースフィルム４２および下ガラス基板３３の各温度変化とベースフィルム４２および下ガラス基板３３の各伸び量について、図７および図８を参照して説明する。
【００２４】
まず、図７に示すように、ベースフィルム４２および下ガラス基板３３の各温度は、接合前の初期の状態では共に室温である。そして、ベースフィルム４２および下ガラス基板３３の予備加熱を別々に開始し、ベースフィルム４２の温度を予め設定された予熱温度Ｔ４（Ｔ４＞Ｔ３）まで上昇させ、下ガラス基板３３の温度を予め設定された予熱温度Ｔ５に上昇させる。これにより、図８に示すように、ベースフィルム４２側の端子配列部は予め設定された量Ｌ４（Ｌ４＞Ｌ３）だけ伸び、下ガラス基板３３側の端子配列部は予め設定された量Ｌ５だけ伸びる。なお、Ｔ３およびＬ３は前述した実施形態での予備加熱温度およびそれによる伸び量である。ここで、（Ｌ４−Ｌ５）＝Ｌ３となるように予めそれぞれの予備加熱温度Ｔ４、Ｔ５を設定しておくと、予備加熱後における接続端子４４の配列ピッチと入力端子３５の配列ピッチとは等しくなる。
【００２５】
次に、本加熱加圧を所定時間実施し、ベースフィルム４２の温度を予熱温度Ｔ４からさらに上昇させて本加熱加圧終了時点で予定した接合温度Ｔ１とし、、下ガラス基板３３の温度を予熱温度Ｔ５からさらに上昇して本加熱加圧終了時点で予定した接合温度Ｔ２とする。これにより、図８に示すように、ベースフィルム４２はさらに（Ｌ１−Ｌ４）だけ伸びて当初からの伸び量が所期の伸び量Ｌ１となり、下ガラス基板３３はさらに（Ｌ２−Ｌ５）だけ伸びて当初からの伸び量が所期の伸び量Ｌ２となる。ここで、（Ｌ１−Ｌ４）＝（Ｌ２−Ｌ５）となるように各予備加熱温度Ｔ４、Ｔ５を予め設定しておくことにより、本加熱加圧時におけるベースフィルム４２の端子配列部の伸び量と下ガラス基板３３の突出部３３ａの伸び量とは同じとなる。したがって、この場合も、接合すべきベースフィルム４２と下ガラス基板３３の熱膨張率の違いおよび伸びの基点の相違による端子列の位置ずれが防止され、端子列同士を常に確実に所期の通り導電接続することができる。
【００２６】
ところで、ポリイミド等からなるベースフィルム４２の場合、予熱温度Ｔ３、Ｔ４は通常約１００℃以上である。一方、室温状態におけるベースフィルム４２の寸法が吸湿により変化している場合がある。しかし、このような場合でも、ベースフィルム４２は予備加熱されて予熱温度Ｔ３、Ｔ４になると十分に乾燥され、予備加熱による伸び量Ｌ３、Ｌ４を含む所期の寸法となり、そしてこの時点で上述の実施形態と同様に位置合わせを行うので、ベースフィルム４２の吸湿による寸法変化の影響を無くすことができる。
【００２７】
また、下ガラス基板３３を予備加熱する場合には、その突出部３３ａ上に配置された異方性導電接着剤３６も予備加熱されることになる。この場合、下ガラス基板３３の予熱温度Ｔ５を、予備加熱によって熱硬化性樹脂３７を導電性粒子３８の流動が抑制される程度の硬さに硬化させる温度に設定すると、本加熱加圧時に熱硬化性樹脂３７が過度に流動することがなく、導電性粒子３８の移動が軽減され、本加熱加圧後における導電性粒子３８の分布を均一にすることができる。
【００２８】
なお、上記実施形態において、フレキシブル回路基板４１の代わりに、ＴＡＢ(tape automated bonding)、ＴＣＰ(tape carrier package)、半導体チップ等を液晶表示パネル３１の突出部３３ａ上に接合するようにしてもよい。さらに、固定台２１上に吸着配置される一方の回路基板の熱膨張率がこれに接合される他方の回路基板の熱膨張率よりも大きい場合には、一方の回路基板を予め設定された予熱温度まで予備加熱するようにしてもよく、あるいは他方の回路基板を予め設定された冷却温度まで予備冷却するようにしてもよい。加えて、上記実施形態において、ベースフィルム４２を室温のままとし、下ガラス基板３３を予め設定された冷却温度まで予備冷却するようにしてもよい。
【００２９】
【発明の効果】
以上説明したように、この発明によれば、接合する前に両回路基板のうち少なくとも一方の回路基板と前記コネクタ部材とを、前記熱硬化性樹脂がその中に含有する前記導電性粒子の流動を抑制できる程度に硬化させ、且つ前記第１の端子列と前記第２の端子列の各端子配列ピッチが同一となる温度まで予備加熱した後、対応する各端子同士が対向するように位置合せするので、この後の接合工程における接合すべき２つの回路基板の熱膨張率の違いや伸びの基点の違いによる端子列の位置ずれを防止し、端子列同士を常に対応する端子同士を正確に対向させることができ、また異方性導電接着剤の導電性粒子の流動が抑制されるので、前記端子同士を確実に導電接続することができる。
【図面の簡単な説明】
【図１】この発明の一実施形態としての回路基板の接合装置の要部を示す斜視図。
【図２】図１に示す接合装置において、フレキシブル回路基板を下ガラス基板上に接合する前の初期の状態を示す断面図。
【図３】図２に示す状態からフレキシブル回路基板を予備加熱した状態を示す断面図。
【図４】図３に示す状態からフレキシブル回路基板を下ガラス基板上に接合した状態を示す断面図。
【図５】図２〜図４に示す場合におけるフレキシブル回路基板および下ガラス基板の各温度変化を示す図。
【図６】図５に示す場合におけるフレキシブル回路基板および下ガラス基板の各伸び量を示す図。
【図７】フレキシブル回路基板および下ガラス基板の各温度変化の他の例を示す図。
【図８】図７に示す場合におけるフレキシブル回路基板および下ガラス基板の各伸び量を示す図。
【図９】従来の回路基板の接合装置の一例の一部を示す斜視図。
【図１０】図９に示す接合装置において、フレキシブル回路基板を下ガラス基板上に接合した状態を示す断面図。
【図１１】上記従来例において、フレキシブル回路基板および下ガラス基板の各温度変化を示す図。
【図１２】図１１に示す場合におけるフレキシブル回路基板および下ガラス基板の伸び量を示す図。
【図１３】図９に示す接合装置において、フレキシブル回路基板を下ガラス基板上に接合する前の初期の状態を示す断面図。
【図１４】図１３においてベースフィルムおよび下ガラス基板の伸びの基点がＢ−Ｂ線で示すように右端部である場合の接合後の状態を説明するために示す断面図。
【符号の説明】
２１固定台
２２ボンディングツール
２３ヒーターチップ
２４支持板
２５吸着脚
３１液晶表示パネル
３２上ガラス基板
３３下ガラス基板
３３ａ突出部
３５入力端子
３６異方性導電接着剤
３７熱硬化性樹脂
３８導電性粒子
４１フレキシブル回路基板
４２ベースフィルム
４３半導体チップ
４４接続端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit board bonding method, and more particularly, to a circuit board bonding method capable of preventing a positional shift of a terminal row due to a difference in thermal expansion coefficient between two circuit boards to be bonded.
[0002]
[Prior art]
For example, in a method for manufacturing a liquid crystal display device, a method in which one circuit board of a liquid crystal display panel and a flexible circuit board are bonded by thermocompression bonding through a connector member such as an anisotropic conductive adhesive therebetween is often used.
[0003]
FIG. 9 is a partial perspective view of an example of a conventional circuit board bonding apparatus used in such a circuit board bonding method. This joining apparatus includes a fixed base 1 with a suction mechanism (not shown), and a movable base with a suction mechanism (not shown) arranged movably in the X and Y directions (horizontal direction) beside the fixed base 1. 2. A bonding tool 3 or the like is provided above the fixed base 1 so as to be movable in the vertical direction.
[0004]
On the fixed base 1, the liquid crystal display panel 4 is positioned and sucked and arranged. In the liquid crystal display panel 4, an upper glass substrate 5 and a lower glass substrate 6 are bonded together via a substantially rectangular frame-shaped sealing material (not shown), and liquid crystal (between the glass substrates 5 and 6 inside the sealing material ( (Not shown) is enclosed, an upper polarizing plate 7 is attached to the upper surface of the upper glass substrate 5, and a lower polarizing plate (not shown) is attached to the lower surface of the lower glass substrate 6. In this case, a predetermined one side portion of the lower glass substrate 6 protrudes from the upper glass substrate 5, and a plurality of input terminals 8 (see FIG. 10) made of a transparent metal such as ITO are provided on the protruding portion 6a. A strip-shaped anisotropic conductive adhesive 9 is temporarily crimped on the input terminal 8. As shown in FIG. 10, the anisotropic conductive adhesive 9 is composed of a thermosetting resin 10 containing a large number of conductive particles 11.
[0005]
A flexible circuit board 12 is positioned and placed on the movable table 2 by suction. The flexible circuit board 12 has a semiconductor chip 14 made of an LSI for driving a liquid crystal display panel mounted on the center of the upper surface of a base film 13 made of polyimide or the like by a COF (chip on film) system. Further, a plurality of connection terminals 15 (see FIG. 10) made of copper or the like are provided connected to the semiconductor chip 14.
[0006]
Next, a description will be given of a case where the terminal portion arranged at one end portion of the flexible circuit board 12 is joined to the terminal arrangement portion on the protruding portion 6a of the lower glass substrate 6 of the liquid crystal display panel 4 by this joining apparatus. First, the liquid crystal display panel 4 is positioned and placed on the fixed base 1 by suction. In this case, a strip-shaped anisotropic conductive adhesive 9 is disposed on the protruding portion 6 a of the lower glass substrate 6. Further, the flexible circuit board 12 is positioned at a predetermined position on the movable base 2 and is disposed by suction. In this state, one end of the flexible circuit board 12 protrudes from the movable table 2 by a predetermined amount and is positioned on the anisotropic conductive adhesive 9.
[0007]
Next, in this state, although not shown, the X and Y direction positions of one end portion of the flexible circuit board 12 and the protruding portion 6a of the lower glass substrate 6 are detected by an image processing position detection device equipped with a camera or the like. To do. And based on this detection result, the movable stand 2 is appropriately moved in the X and Y directions, and alignment with respect to the protruding portion 6a of the lower glass substrate 6 at one end of the flexible circuit board 12 is performed. Next, the bonding tool 3 is lowered, and the lower surface of the flexible circuit board 12 is pressed against the upper surface of the anisotropic conductive adhesive 9 on the protruding portion 6a of the lower glass substrate 6 by the lower surface thereof. Then, the lower surface of the one end portion of the flexible circuit board 12 is joined to an appropriate position on the protruding portion 6a of the liquid crystal display panel 4 via the anisotropic conductive adhesive 9 by heating and pressing with the bonding tool 3, and each terminal Are conductively connected through the conductive particles in the anisotropic conductive adhesive 9.
[0008]
This ideal bonding state is shown in FIG. However, in FIG. 10, for convenience of illustration, only three of the connection terminals 15 and the input terminals 8 are illustrated. This ideal bonded state is obtained when the thermal expansion coefficient of the base film 13 is equal to the thermal expansion coefficient of the lower glass substrate 6 of the liquid crystal display panel 4. The arrangement pitch of the connection terminals 15 and the arrangement pitch of the input terminals 8 are obtained. Are the same, and the connection terminal 15 and the input terminal 8 facing each other are conductively connected via conductive particles 11 interposed therebetween and appropriately elastically deformed. Further, the lower surface of one end portion of the flexible circuit board 12 including the connection terminal 15 and the upper surface of the protruding portion 6 a of the lower glass substrate 6 including the input terminal 8 are bonded via the thermosetting resin 10.
[0009]
By the way, since the thermal expansion coefficient of the base film 13 made of polyimide or the like of the flexible circuit board 12 is larger than the thermal expansion coefficient of the lower glass substrate 6 of the liquid crystal display panel 4, the heating temperature of the bonding tool 3 at the time of bonding is usually 200 to 200. Due to the high temperature of about 300 ° C., the extension amount in the X direction of the portion including the connection terminal 15 of the base film 13 (hereinafter, simply referred to as the extension amount) causes the input terminal 8 of the protruding portion 6a of the lower glass substrate 6 to It becomes larger than the amount of elongation in the X direction of the included portion (hereinafter simply referred to as the amount of elongation). That is, as shown in FIG. 11, the temperatures of the base film 13 and the lower glass substrate 6 are both room temperature before the start of bonding, and both rise substantially in the same manner even when the bonding is started and heated. At that time, the temperature of the base film 13 becomes the joining temperature T1, and the temperature of the lower glass substrate 6 becomes the joining temperature T2 that is slightly lower than the joining temperature T1 of the base film 13. However, as shown in FIG. 12, the elongation L1 of the base film 13 becomes considerably larger than the elongation L2 of the lower glass substrate 6 at the end of bonding. The definition of the elongation amounts L1 and L2 will be described later.
[0010]
Therefore, in consideration of the difference (L1−L2) between the elongation amounts L1 and L2, in the initial state before joining, as shown in FIG. 13, the arrangement pitch P1 of the connection terminals 15 of the flexible circuit board 12 is set to The elongation difference (L1−L2) is made smaller than the arrangement pitch P2 of the input terminals 8 of the protrusions 6a of the lower glass substrate 6 by a predetermined amount so as to cancel out. Here, the elongation amounts L1 and L2 are the respective increments of the total value of the arrangement pitches P1 and P2 of the terminals 15 and 8, that is, the terminals 15a and 15b at the left and right ends shown in FIG. This is an increase in the length between the centers in the width direction of 8a and 8b.
[0011]
[Problems to be solved by the invention]
By the way, in the said conventional joining method, only the position alignment with respect to the protrusion part 6a of the lower glass substrate 6 of the one end part of the flexible circuit board 12 is performed, and it is by the heating at the time of joining of the base film 13 and the lower glass substrate 6 It is difficult to control the base point of elongation. The base point of the elongation changes slightly depending on the contact condition of the heater chip, and the base point of the elongation due to heating at the time of joining the base film 13 and the lower glass substrate 6 is indicated by the AA line in FIG. In the case where the center is in the left-right direction, the base film 13 and the lower glass substrate 6 are equally extended in the left-right direction, so that the arrangement position of the connection terminals 15 and the arrangement of the input terminals 8 are as shown in FIG. The position can be substantially the same. However, when the base point of elongation by heating at the time of joining the base film 13 and the lower glass substrate 6 is, for example, the right end as shown by the line BB in FIG. 13, the base film 13 and the lower glass substrate 6 are both By extending almost in the left direction, the arrangement position of the connection terminal 15 and the arrangement position of the input terminal 8 are shifted as shown in FIG. As a result, there is a problem in that the facing area between the connection terminal 15 and the input terminal 8 decreases, the number of conductive particles 11 interposed therebetween decreases, and the connection resistance increases. In particular, when the arrangement pitch of the connection terminals 15 and the input terminals 8 is miniaturized, it becomes a big trouble.
The object of the present invention is to prevent positional displacement between the respective terminal arrays due to the difference in thermal expansion coefficient between the two circuit boards to be joined, and to ensure that the corresponding terminals of both terminal arrays are accurately opposed to each other. It is to provide a method for joining circuit boards to be connected.
[0012]
[Means for Solving the Problems]
  The circuit board bonding method according to the present invention corresponds to the first circuit board including the first terminal array in which a plurality of terminals are arranged and each terminal of the first terminal array as described in claim 1. A second circuit board having a second terminal array in which a plurality of terminals are arranged, with each of the first terminal array and the second terminal array facing each other.It consists of an anisotropic conductive adhesive containing conductive particles in a thermosetting resinIn the method for joining circuit boards, wherein the first terminal row and the second terminal row are electrically connected via the connector member, the first terminal row and the second terminal row are joined together by a connector member. At least one of the first and second circuit boards formed by previously changing the arrangement pitch of the second terminal rows.And the connector member are cured to such an extent that the thermosetting resin can suppress the flow of the conductive particles contained therein, andAt a temperature at which the terminal arrangement pitches of the first terminal row and the second terminal row are the samePreliminary process for preheatingAnd after the preliminary step, the first circuit board and the second circuit board are aligned such that corresponding terminals of the first terminal row and the second terminal row face each other. Positioning step, and after the positioning step, the first circuit board and the second circuit board are interposed with the connector member interposed therebetween.furtherThe method includes a joining step of joining the first terminal row and the second terminal row by applying pressure while heating.
  According to the first aspect of the present invention, before joining, at least one of the circuit boards is bonded.And the connector member are cured to such an extent that the flow of the conductive particles contained in the thermosetting resin can be suppressed, and each terminal arrangement of the first terminal row and the second terminal row is arranged. After preheating up to a temperature at which the pitch is the same, the corresponding terminals are aligned so that they face each other.To prevent misalignment of terminal rows due to differences in thermal expansion coefficients and elongation base points of the two circuit boards to be joined, and to make sure that the terminal rows always correspond to each other with their corresponding terminals accurately facing each other. Can do.
  In the present invention, as described in claim 2, the temperatures of the first circuit board and the second circuit board at the end of the preliminary process are the same as the first terminal row in the bonding process and the temperature of the first circuit board, respectively. The temperature is set so that the elongation amounts of the second terminal rows are equal.
  According to a third aspect of the present invention, in the present invention, the first circuit board has a higher coefficient of thermal expansion than the second circuit board, and the first circuit board is in a state before the preliminary process. The second terminal row is more suitable for joining circuit boards having a larger terminal pitch.The
  The present invention also provides:Claim 4As described above, the first circuit board is one circuit board of a liquid crystal display panel, and the second circuit board is suitable for joining circuit boards that are flexible circuit boards.
  The circuit board bonding method of another invention of the present application is as follows:Claim 5A plurality of first terminals forming a first terminal row of the first circuit board, and second terminals arranged on the second circuit board corresponding to the first terminals, respectively. In the circuit board joining method in which the second terminals to be formed are electrically joined to each other through an anisotropic conductive adhesive containing conductive particles in a thermosetting insulating resin.The anisotropic conductive adhesive is used together with one of the first circuit board and the second circuit board on which the first terminal row and the second terminal row formed with different arrangement pitches in advance are formed. And hardened to such a degree that the flow of the conductive particles is suppressed, and heated to a temperature at which the terminal arrangement pitches of the first terminal row and the second terminal row are the same.After the preliminary step and the preliminary step are completed, the first circuit board and the second circuit board are pressed while being heated with the anisotropic conductive adhesive interposed therebetween, and the insulating resin is added to the preliminary circuit board. It is further characterized by comprising a bonding step of further curing than the state cured in the step, and conductively connecting the first terminal row and the second terminal row via the conductive particles. is there.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view of a main part of a circuit board bonding apparatus according to an embodiment of the present invention. This joining apparatus includes a fixed base 21 with a suction mechanism (not shown). A bonding tool 22 is disposed above the fixed base 21. The bonding tool 22 includes a heater chip 23 and is attached to one side of the lower surface of a support plate 24 with a suction mechanism (not shown). The bonding tool 22 including the heater chip 23 has a heating temperature control function capable of instantaneously setting a plurality of heating temperatures. Adsorption legs 25 are provided at the other four corners of the lower surface of the support plate 24. The lower surface of the adsorption leg 25 becomes a pressure surface lower than the atmospheric pressure by the action of the adsorption mechanism. The height position of the lower surface of the suction leg 25 is substantially the same as the height position of the lower surface of the bonding tool 22. The heater chip 23, the support plate 24, and the suction legs 25 are integrally moved in the X, Y, Z direction (for positioning) and the rotation angle θ (for posture adjustment) in the XY plane. It has become.
[0014]
On the fixed base 21, the liquid crystal display panel 31 is positioned in the X, Y, and θ directions and is arranged to be sucked. In the liquid crystal display panel 31, an upper glass substrate 32 and a lower glass substrate 33 are bonded together through a substantially rectangular frame-shaped sealing material (not shown), and liquid crystal ( (Not shown) is enclosed, an upper polarizing plate 34 is attached to the upper surface of the upper glass substrate 32, and a lower polarizing plate (not shown) is attached to the lower surface of the lower glass substrate 33. In this case, one predetermined side of the lower glass substrate 33 protrudes from the upper glass substrate 32, and a plurality of input terminals 35 (see FIG. 2) made of a transparent metal such as ITO are provided on the protrusion 33a. On the input terminal 35, a strip-like anisotropic conductive adhesive 36 is temporarily crimped. As shown in FIG. 2, the anisotropic conductive adhesive 36 is composed of a thermosetting resin 37 containing a large number of conductive particles 38.
[0015]
On the lower surface of the four suction legs 25, the flexible circuit board 41 is positioned by suction in the X, Y, and θ directions. In the flexible circuit board 41, a semiconductor chip 43 made of LSI or the like for driving a liquid crystal display panel is mounted in the center of the upper surface of a base film 42 made of polyimide or the like by a COF (chip on film) method. Further, a plurality of connection terminals 44 (see FIG. 2) made of copper or the like are provided connected to the semiconductor chip 43.
[0016]
Next, a case where one end portion of the flexible circuit board 41 is joined to the protruding portion 33a of the lower glass substrate 33 of the liquid crystal display panel 31 with this joining device will be described. First, the liquid crystal display panel 31 is sucked and arranged on the fixed base 21 with its position and orientation determined in the X, Y, and θ directions. In this case, a strip-shaped anisotropic conductive adhesive 36 is provisionally pressure-bonded and disposed on the protruding portion 33 a of the lower glass substrate 33. Further, the flexible circuit board 41 is positioned on the lower surfaces of the four suction legs 25 by being positioned in the X, Y, and θ directions. In this state, the one end part where the connection terminals 44 of the flexible circuit board 41 are arranged side by side is arranged so as to be in close contact with the front end surface of the heater chip 23 serving as a thermocompression bonding head. Note that the front end surface of the heater chip may also have an adsorption function, and one end of the flexible circuit board 41 may be adsorbed on the front end surface.
[0017]
Here, in FIG. 1, the bonding tool 22 is illustrated so as to be positioned above the protruding portion 33 a of the liquid crystal display panel 31 that is sucked and disposed on the fixed base 21. It is moved in the Y direction at the upper limit position and is positioned at a standby position that does not face the fixed base 21. The relationship between the connection terminal 44 of the base film 42 and the input terminal 35 of the lower glass substrate 33 in this state is shown in FIG. However, in FIG. 2, for convenience of illustration, only three of the connection terminals 44 and the input terminals 35 are illustrated. In the state shown in FIG. 2, that is, in the initial state before joining, the difference (L1−) between the extension amount L1 of the base film 42 and the extension amount L2 of the lower glass substrate 33 at the end of the main heating and pressurization shown in FIG. In consideration of L2), the arrangement pitch P1 of the connection terminals 44 is smaller than the arrangement pitch P2 of the input terminals 35 by a predetermined amount so as to cancel out the difference (L1−L2) in the expansion amount.
[0018]
Next, in a state where the bonding tool 22 is positioned at the standby position, one end portion where the connection terminals 44 of the base film 42 are arranged in parallel is preliminarily heated by the bonding tool 22 including the heater chip 23 and a preset preheating temperature. Heat until Then, as shown in FIG. 5, the temperature of the lower glass substrate 33 remains at room temperature, but the temperature of the base film 42 rises to a preset preheating temperature T3. Thereby, as shown in FIG. 6, the lower glass substrate 33 does not extend, but the base film 42 extends by a preset amount L3. Here, the extension amount L3 of the base film 42 is set in advance so as to be the total value of the difference (P2−P1) between the arrangement pitch P2 of the input terminals 35 and the arrangement pitch P1 of the connection terminals 44 shown in FIG. In other words, as shown in FIG. 3, the arrangement pitch P <b> 3 of the connection terminals 44 is equal to the arrangement pitch P <b> 2 of the input terminals 35.
[0019]
Next, in this state, although not shown, the X and Y direction positions of one end portion of the flexible circuit board 41 and the protruding portion 33a of the lower glass substrate 33 are detected by an image processing position detection device equipped with a camera or the like. To do. Then, based on this detection result, the bonding tool 22 located at the standby position is appropriately moved in the X and Y directions to perform alignment with the protruding portion 33a of the lower glass substrate 33 at one end of the flexible circuit board 41, The connection terminal 44 of the flexible circuit board 41 is accurately positioned at the alignment position above the corresponding input terminal 35.
[0020]
Next, the bonding tool 22 is lowered by a predetermined amount in the Z direction, and the lower surface of one end of the flexible circuit board 41 is brought into pressure contact with the upper surface of the anisotropic conductive adhesive 36 on the protruding portion 33 a of the lower glass substrate 33. Then, the heater chip 23 generates heat and the bonding tool 22 is heated to the main heating temperature to perform main heating and pressurization. As a result of this main heating and pressing, as shown in FIG. 5, the temperature of the base film 42 further rises from the preheating temperature T3 and reaches the expected bonding temperature T1 at the end of the main heating and pressing, and at the same time, the lower glass substrate 33. The temperature rises from room temperature to the junction temperature T2 scheduled at the end of the main heating and pressurization. As a result, as shown in FIG. 6, the base film 42 is further extended by (L1-L3), the amount of elongation from the beginning becomes the desired amount of elongation L1, and the lower glass substrate 33 is extended by the desired amount L2. Here, by setting the preheating temperature T3 in advance such that L2 = (L1−L3), the amount of elongation at one end of the base film 42 and the protruding portion of the lower glass substrate 33 at the time of main heating and pressurization are set. The amount of elongation of 33a is the same.
[0021]
As a result, even if the base point of elongation of the base film 13 and the lower glass substrate 6 is the center in the left-right direction as shown by the line AA in FIG. 3, it is the right end as shown by the line BB. That is, as shown in FIG. 4, the arrangement pitch of the connection terminals 44 and the arrangement pitch of the input terminals 35 are equally enlarged everywhere, and the connection terminals 44 are superimposed on the corresponding input terminals 35 so as to face each other. Arrangement. In this state, the connection terminal 44 and the input terminal 35 facing each other are reliably conductively connected via the conductive particles 38 interposed between them and appropriately elastically deformed. Further, the lower surface of one end portion of the flexible circuit board 41 including the connection terminals 44 and the upper surface of the protruding portion 33 a of the lower glass substrate 33 including the input terminals 35 are bonded via a thermosetting resin 37.
[0022]
As described above, in this joining method, after the flexible circuit board 41 is preheated before the main heating and pressing so that the pitch between the connection terminals is the same as the pitch between the input terminals to be joined and the positioning is performed. The flexible circuit board is subjected to the main heating and pressing so that the extension amount (L1-L3) of the one end portion of the flexible circuit board 41 and the extension amount L2 of the protruding portion 33a of the lower glass substrate 33 are equal in the main heating and pressing. Since the preheating temperature T3 of one end portion of 41 is set, the positional deviation of the terminal rows due to the difference in the thermal expansion coefficient between the base film 42 and the lower glass substrate 33 to be joined and the difference in the elongation base point is prevented. Conductive connection can always be ensured as expected.
[0023]
In the above embodiment, the case where only the base film 42 is preheated has been described. However, the present invention is not limited thereto, and the base film 42 is preheated by the bonding tool 22 and the lower glass substrate 33 is heated by a heating means (not shown). You may make it preheat by the fixed stand 21 provided with. Next, each temperature change of the base film 42 and the lower glass substrate 33 and each elongation amount of the base film 42 and the lower glass substrate 33 in this case will be described with reference to FIGS. 7 and 8.
[0024]
First, as shown in FIG. 7, the temperatures of the base film 42 and the lower glass substrate 33 are both room temperature in the initial state before bonding. Then, preheating of the base film 42 and the lower glass substrate 33 is started separately, the temperature of the base film 42 is raised to a preset preheating temperature T4 (T4> T3), and the temperature of the lower glass substrate 33 is set in advance. The preheat temperature T5 is increased. Thereby, as shown in FIG. 8, the terminal arrangement part on the base film 42 side extends by a preset amount L4 (L4> L3), and the terminal arrangement part on the lower glass substrate 33 side is by a preset amount L5. extend. Note that T3 and L3 are the preheating temperature and the elongation amount in the above-described embodiment. Here, if the preheating temperatures T4 and T5 are set in advance so that (L4−L5) = L3, the arrangement pitch of the connection terminals 44 and the arrangement pitch of the input terminals 35 after the preheating are equal. Become.
[0025]
Next, the main heating and pressing are performed for a predetermined time, and the temperature of the lower glass substrate 33 is preheated by raising the temperature of the base film 42 from the preheating temperature T4 to the bonding temperature T1 scheduled at the end of the main heating and pressing. The temperature is further increased from the temperature T5, and is set to a bonding temperature T2 scheduled at the end of the main heating and pressing. As a result, as shown in FIG. 8, the base film 42 is further extended by (L1-L4), and the amount of elongation from the beginning becomes the desired amount of extension L1, and the lower glass substrate 33 is further extended by (L2-L5). Thus, the amount of growth from the beginning becomes the desired amount of growth L2. Here, by setting the preheating temperatures T4 and T5 in advance so that (L1−L4) = (L2−L5), the extension amount of the terminal arrangement portion of the base film 42 at the time of the main heating and pressurization. And the extension amount of the protruding portion 33a of the lower glass substrate 33 are the same. Therefore, also in this case, the terminal row is prevented from being displaced due to the difference in the thermal expansion coefficient between the base film 42 and the lower glass substrate 33 to be joined and the difference in the base point of the extension, and the terminal rows are always as expected. Conductive connection can be made.
[0026]
By the way, in the case of the base film 42 made of polyimide or the like, the preheating temperatures T3 and T4 are usually about 100 ° C. or higher. On the other hand, the dimension of the base film 42 at room temperature may change due to moisture absorption. However, even in such a case, the base film 42 is preheated and sufficiently dried when the preheat temperatures T3 and T4 are reached, and the desired dimensions including the elongation amounts L3 and L4 due to the preheat are obtained. Since alignment is performed in the same manner as in the embodiment, the influence of dimensional change due to moisture absorption of the base film 42 can be eliminated.
[0027]
When the lower glass substrate 33 is preheated, the anisotropic conductive adhesive 36 disposed on the protruding portion 33a is also preheated. In this case, if the preheating temperature T5 of the lower glass substrate 33 is set to a temperature at which the thermosetting resin 37 is cured to such a degree that the flow of the conductive particles 38 is suppressed by preheating, The curable resin 37 does not flow excessively, the movement of the conductive particles 38 is reduced, and the distribution of the conductive particles 38 after the main heating and pressing can be made uniform.
[0028]
In the above embodiment, instead of the flexible circuit board 41, TAB (tape automated bonding), TCP (tape carrier package), a semiconductor chip or the like may be bonded onto the protruding portion 33a of the liquid crystal display panel 31. . Furthermore, when the thermal expansion coefficient of one circuit board adsorbed and disposed on the fixed base 21 is larger than the thermal expansion coefficient of the other circuit board joined thereto, one circuit board is preheated in advance. It may be preheated to a temperature, or the other circuit board may be precooled to a preset cooling temperature. In addition, in the above embodiment, the base film 42 may be kept at room temperature, and the lower glass substrate 33 may be precooled to a preset cooling temperature.
[0029]
【The invention's effect】
  As described above, according to the present invention, at least one of the circuit boards before joining is provided.And the connector member are cured to such an extent that the flow of the conductive particles contained in the thermosetting resin can be suppressed, and each terminal arrangement of the first terminal row and the second terminal row is arranged. After preheating to a temperature where the pitch is the same,Align so that each corresponding terminal faces each otherSo in the subsequent joining processIt is possible to prevent the positional deviation of the terminal rows due to the difference in thermal expansion coefficient between the two circuit boards to be joined and the difference in the base point of elongation, and the terminals always corresponding to each other can be accurately opposed to each other.Since the flow of the conductive particles of the anisotropic conductive adhesive is suppressed, the terminals areConductive connection can be ensured.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a main part of a circuit board bonding apparatus according to an embodiment of the present invention.
2 is a cross-sectional view showing an initial state before the flexible circuit board is bonded onto the lower glass substrate in the bonding apparatus shown in FIG. 1;
3 is a cross-sectional view showing a state in which a flexible circuit board is preheated from the state shown in FIG. 2;
4 is a cross-sectional view showing a state in which a flexible circuit board is bonded onto a lower glass substrate from the state shown in FIG. 3;
FIG. 5 is a diagram showing changes in temperature of the flexible circuit board and the lower glass substrate in the case shown in FIGS.
6 is a view showing the amount of elongation of each of the flexible circuit board and the lower glass substrate in the case shown in FIG.
FIG. 7 is a view showing another example of each temperature change of the flexible circuit board and the lower glass substrate.
8 is a diagram showing the amount of elongation of each of the flexible circuit board and the lower glass substrate in the case shown in FIG.
FIG. 9 is a perspective view showing a part of an example of a conventional circuit board bonding apparatus.
10 is a cross-sectional view showing a state in which a flexible circuit board is bonded onto a lower glass substrate in the bonding apparatus shown in FIG. 9;
FIG. 11 is a diagram showing changes in temperature of the flexible circuit board and the lower glass substrate in the conventional example.
12 is a view showing the elongation amount of the flexible circuit board and the lower glass substrate in the case shown in FIG.
13 is a cross-sectional view showing an initial state before the flexible circuit board is bonded onto the lower glass substrate in the bonding apparatus shown in FIG. 9;
14 is a cross-sectional view for explaining a state after joining in the case where the base point of elongation of the base film and the lower glass substrate is the right end as shown by the line BB in FIG. 13;
[Explanation of symbols]
21 fixed base
22 Bonding tool
23 Heater chip
24 Support plate
25 Adsorption legs
31 LCD panel
32 Upper glass substrate
33 Lower glass substrate
33a protrusion
35 Input terminal
36 Anisotropic conductive adhesive
37 Thermosetting resin
38 conductive particles
41 Flexible circuit board
42 Base film
43 Semiconductor chip
44 connection terminals

Claims

A second circuit including a first circuit board having a first terminal array in which a plurality of terminals are arranged and a second terminal array in which a plurality of terminals corresponding to the respective terminals of the first terminal array are arranged. The substrate is joined by a connector member made of an anisotropic conductive adhesive containing conductive particles in a thermosetting resin with the first terminal row and the second terminal row facing each other. In the circuit board joining method for conductively connecting the corresponding terminals of the first terminal row and the second terminal row via the connector member,
At least one of the first and second circuit boards formed by differentiating the arrangement pitch of the first terminal row and the second terminal row in advance and the connector member, the thermosetting Preliminarily preheated to a temperature at which the terminal arrangement pitch of the first terminal row and the second terminal row is the same, and the resin is cured to such an extent that the flow of the conductive particles contained therein can be suppressed. Process ,
After the preliminary step, the first circuit board and the second circuit board are positioned so that the corresponding terminals of the first terminal row and the second terminal row face each other. Process,
After the positioning step, the first circuit board and the second circuit board are pressurized while further heating with the connector member interposed therebetween, and the first terminal row and the second terminal A circuit board bonding method comprising: a bonding step of bonding rows.

2. The temperature of the first circuit board and the second circuit board at the end of the preliminary process is determined by the first terminal array and the second terminal array in the joining step according to claim 1. A circuit board bonding method characterized in that the respective elongation amounts due to temperature rise are equal to each other.

3. The invention according to claim 1, wherein the first circuit board has a larger coefficient of thermal expansion than the second circuit board, and the second circuit board has a second coefficient of thermal expansion greater than that of the first terminal row in a state before a preliminary process. A circuit board bonding method, wherein the terminal row has a larger terminal pitch.

In the invention described in claim 1, wherein the first circuit board is one substrate of the liquid crystal display panel, circuit board, wherein said second circuit board is a flexible circuit board Joining method.

A plurality of first terminals that form a first terminal row of the first circuit board, and a second that is arranged on the second circuit board so as to correspond to the first terminals and form a second terminal row In the circuit board joining method, the terminal is electrically joined via an anisotropic conductive adhesive containing conductive particles in a thermosetting insulating resin.
The anisotropic conductive adhesive is used together with one of the first circuit board and the second circuit board on which the first terminal row and the second terminal row formed with different arrangement pitches in advance are formed. A preliminary step of curing the conductive particles to such a degree that the flow of the conductive particles is suppressed, and heating to a temperature at which the terminal arrangement pitches of the first terminal row and the second terminal row are the same ;
After completion of the preliminary process, the first circuit board and the second circuit board are pressed with further heating with the anisotropic conductive adhesive interposed therebetween, and the insulating resin is cured in the preliminary process. A circuit board bonding method comprising: a bonding step of further curing the first terminal row and the second terminal row through the conductive particles; and a step of conductively connecting the first terminal row and the second terminal row via the conductive particles. .