JP3925746B2 - Circuit board - Google Patents
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- JP3925746B2 JP3925746B2 JP03098397A JP3098397A JP3925746B2 JP 3925746 B2 JP3925746 B2 JP 3925746B2 JP 03098397 A JP03098397 A JP 03098397A JP 3098397 A JP3098397 A JP 3098397A JP 3925746 B2 JP3925746 B2 JP 3925746B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、例えばフリップチップ実装方式により半導体チップを基板と接着剤で接着固定すると共に両者の電極同士を電気的に接続することにより得られる回路板に関する。
【０００２】
【従来の技術】
半導体実装分野では、低コスト化・高精化に対応した新しい実装形態としてＩＣチップを直接プリント基板やフレキシブル配線板に搭載するフリップチップ実装が注目されている。フリップチップ実装方式としては、チップの端子にはんだバンプを設け、はんだ接続を行う方式や導電性接着剤を介して電気的接続を行う方式が知られている。これらの方式では、接続するチップと基板の熱膨張係数差に基づくストレスが、各種環境下に曝した場合、接続界面で発生し接続信頼性が低下するという問題がある。このため、接続界面のストレスを緩和する目的で一般にエポキシ樹脂系のアンダフィル材をチップ／基板の間隙に注入する方式が検討されている。しかし、このアンダフィルの注入工程は、プロセスを煩雑化し、生産性、コストの面で不利になるという問題がある。このような問題を解決すべく最近では、異方導電性と封止機能を有する異方導電性接着剤を用いたフリップチップ実装が、プロセス簡易性という観点から注目されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、チップを異方導電接着剤を介して直接基板に搭載する場合、温度サイクル試験下ではチップと基板の熱膨張係数差に基づくストレスが接続部において生じ、熱衝撃試験、ＰＣＴ試験、はんだバス浸漬試験などの信頼性試験を行うと接続抵抗の増大や接着剤の剥離が生じるという問題がある。また、チップの接続端子に突起電極が形成されている場合では、信頼性試験においてチップと基板の熱膨張係数差に基づくストレスが突起電極とチップ界面に集中し、突起電極がチップ電極界面から剥離し、導通不良が生じるという問題がある。
本発明は、接続部での接続抵抗の増大や接着剤の剥離がなく、接続信頼性が大幅に向上する回路板を提供するものである。
【０００４】
【課題を解決するための手段】
本発明の回路板は、第一の接続端子を有する第一の回路部材と、第一の回路部材より熱膨張係数が大きい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接着剤を介在させ、加熱加圧し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た回路板であって、前記接着剤が、接着樹脂組成物１００重量部に無機質充填材を１０〜２００重量部の割合で含有してなる接着剤層１と接着剤組成物を主成分としてなる接着剤層２を備えた多層構成接着剤であり、接着剤層１及び／又は接着剤層２の接着剤組成物の硬化後の４０℃での弾性率が３０〜１５００ＭＰａで、前記接着剤層１が前記第一の回路部材側に接着していることを特徴とするものである。
【０００５】
接着剤層１及び／又は接着剤層２の接着剤組成物の硬化後の４０℃での弾性率は３０〜１５００ＭＰａであるのが好ましく、接着剤層１及び／又は接着剤層２の接着剤組成物はエポキシ樹脂、アクリルゴム、潜在性硬化剤を含有しているものが使用される。アクリルゴムは、その分子中にグリシジルエーテル基を含有しているものが好ましい。
無機質充填材の平均粒径は３ミクロン以下が好ましく、接着剤層２の接着剤組成物には導電粒子を０．１〜３０体積％含有しても良く、接着剤層２の接着剤組成物に含有されている導電粒子の平均粒径が無機充填材の平均粒径に比べて大きいことが好ましい。
【０００６】
【発明の実施の形態】
本発明において用いられる回路部材として半導体チップ、プリント基板、ポリイミドやポリエステルを基材としたフレキシル配線板があげられる。半導体チップや基板の電極パッド上には、めっきで形成されるバンプや金ワイヤの先端をトーチ等により溶融させ、金ボールを形成し、このボールを電極パッド上に圧着した後、ワイヤを切断して得られるワイヤバンプなどの突起電極を設け、接続端子として用いることができる。
【０００７】
本発明において用いられる接着樹脂組成物としては、エポキシ樹脂とイミダゾール系、ヒドラジド系、三フッ化ホウ素−アミン錯体、スルホニウム塩、アミンイミド、ポリアミンの塩、ジシアンジアミド等の潜在性硬化剤の混合物が用いられ、回路部材の熱膨張係数差に基づくストレスを緩和するためには、接着後の４０℃での弾性率が３０〜１５００ＭＰａの接着樹脂組成物が好ましい。例えば、接続時の良好な流動性や高接続信頼性を得られる接着樹脂組成物として、エポキシ樹脂とイミダゾール系、ヒドラジド系、三フッ化ホウ素−アミン錯体、スルホニウム塩、アミンイミド、ポリアミンの塩、ジシアンジアミド等の潜在性硬化剤の混合物に、接着後の４０℃での弾性率が３０〜１５００ＭＰａになるようにアクリルゴムを配合した接着剤があげられる。接着フィルム硬化物の弾性率は、例えば、レオロジ（株）製レオスペクトラＤＶＥ−４（引っぱりモード、周波数１０Ｈｚ、５℃／ｍｉｎで昇温）を使用して測定できる。
【０００８】
本発明で用いるアクリルゴムとしては、アクリル酸、アクリル酸エステル、メタクリル酸エステルまたはアクリロニトリルのうち少なくともひとつをモノマー成分とした重合体または共重合体があげられ、中でもグリシジルエーテル基を含有するグリシジルアクリレートやグリシジルメタクリレートを含む共重合体系アクリルゴムが好適に用いられる。
これらアクリルゴムの分子量は、接着剤の凝集力を高める点から２０万以上が好ましい。アクリルゴムの接着剤中の配合量は、１５ｗｔ％以下であると接着後の４０℃での弾性率が１５００ＭＰａを越えてしまい、また４０ｗｔ％以上になると低弾性率化は図れるが接続時の溶融粘度が高くなり接続電極界間、または接続電極と導電粒子界面の溶融接着剤の排除性が低下するため、接続電極間または接続電極と導電粒子間の電気的導通を確保できなくなる。このため、アクリル配合量としては１５〜４０ｗｔ％が好ましい。接着剤に配合されたこれらのアクリルゴムは、ゴム成分に起因する誘電正接のピーク温度が４０〜６０℃付近にあるため、接着剤の低弾性率化を図ることができる。また、接着剤にはフィルム形成性をより容易にするためにフェノキシ樹脂などの熱可塑性樹脂を配合することもできる。特に、フェノキシ樹脂は、エポキシ樹脂と構造が類似しているため、エポキシ樹脂との相溶性、接着性に優れるなどの特徴を有するので好ましい。フィルム形成は、これら少なくともエポキシ樹脂、アクリルゴム、フェノキシ樹脂、潜在性硬化剤からなる接着組成物と導電粒子を有機溶剤に溶解あるいは分散により液状化して、剥離性基材上に塗布し、硬化剤の活性温度以下で溶剤を除去することにより行われる。この時用いる溶剤は、芳香族炭化水素系と含酸素系の混合溶剤が材料の溶解性を向上させるため好ましい。
【０００９】
本発明に用いられる無機質充填材としては、特に限定するものではなく、例えば、溶融シリカ、結晶質シリカ、ケイ酸カルシウム、アルミナ、炭酸カルシウム等の粉体があげられる。無機充填材の配合量は、接着樹脂組成物１００重量部に対して１０〜２００重量部であり、熱膨張係数を低下させるには配合量が大きいほど効果的であるが、多量に配合すると接着性や接続部での接着剤の排除性低下に基づく導通不良が発生する。配合量が小さいと熱膨張係数を充分低下できないため、２０〜９０重量部が好ましい。また、その平均粒径は、接続部での導通不良を防止する目的で３ミクロン以下にするのが好ましい。また接続時の樹脂の流動性の低下及びチップのパッシベーション膜のダメージを防ぐ目的で球状フィラを用いることが望ましい。
【００１０】
本発明の接着剤には、チップのバンプや回路電極の高さばらつきを吸収するために、異方導電性を積極的に付与する目的で導電粒子を分散することもできる。本発明において導電粒子は例えばＡｕ、Ｎｉ、Ａｇ、Ｃｕ、Ｗやはんだなどの金属粒子またはこれらの金属粒子表面に金やパラジウムなどの薄膜をめっきや蒸着によって形成した金属粒子であり、ポリスチレン等の高分子の球状の核材にＮｉ、Ｃｕ、Ａｕ、はんだ等の導電層を設けた導電粒子を用いることができる。粒径は基板の電極の最小の間隔よりも小さいことが必要で、電極の高さばらつきがある場合、高さばらつきよりも大きいことが好ましく、かつ無機質充填材の平均粒径より大きいことが好ましく、１μｍ〜１０μｍが好ましい。また、接着剤に分散される導電粒子量は、０．１〜３０体積％であり、好ましくは０．２〜１５体積％である。
【００１１】
【実施例】
実施例１
フェノキシ樹脂５０ｇと、ブチルアクリレート（４０部）、エチルアクリレート（３０部）、アクリロニトリル（３０部）及びグリシジルメタクリレート（３部）を共重合したアクリルゴム（分子量：８５万）１２５ｇを酢酸エチル４００ｇに溶解し、３０％溶液を得た。ついで、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（エポキシ当量１８５）３２５ｇをこの溶液に加え、撹拌し、溶融シリカ（平均粒子径：０．５μｍ）を樹脂接着剤組成物１００重量部に対して４０重量部を分散してフィルム塗工用溶液を得た。この溶液をセパレータ（シリコーン処理したポリエチレンテレフタレートフィルム、厚み４０μｍ）にロールコータで塗布し、１００℃１０分乾燥し厚み２５μｍの接着フィルム１を作製した。なお、この接着フィルム１の溶融シリカを除いた接着樹脂組成物のみの動的粘弾性測定器で測定した４０℃の弾性率は、８００ＭＰａであった。接着フィルム１の作成において溶融シリカを分散する代わりにニッケル粒子（直径：３μｍ）を２ｖｏｌ％分散する以外は、同様な方法で厚み２５μｍの接着フィルム２を作製した。次に作製した接着フィルム１と接着フィルム２をラミネートしてフィルム状接着剤を得た。このフィルム状接着剤を用いて金バンプ（面積：８０μｍｘ８０μｍ、スペース３０μｍ、高さ：１５μｍ、バンプ数２８８）付きチップ（１０ｍｍｘ１０ｍｍ、厚み：０．５ｍｍ）とＮｉ／ＡｕめっきＣｕ回路プリント基板の接続を以下に示すように行った。このフィルム状接着剤の接着フィルム２（１２ｍｍｘ１２ｍｍ）をＮｉ／ＡｕめっきＣｕ回路プリント基板（電極高さ：２０μｍ、厚み：０．８ｍｍ）に８０℃、１０ｋｇｆ／ｃｍ ２ で貼りつけた後、セパレータを剥離し、接着フィルム１側にチップを対向し、チップのバンプとＮｉ／ＡｕめっきＣｕ回路プリント基板（厚み：０．８ｍｍ）の位置あわせを行った。ついで、１８０℃、５０ｇ／バンプ、２０秒の条件でチップ上方から加熱、加圧を行い、本接続を行った。本接続後の接続抵抗は、１バンプあたり最高で６ｍΩ、平均で２ｍΩ、絶縁抵抗は１０ ８ Ω以上であり、これらの値は−５５〜１２５℃の熱衝撃試験１０００サイクル処理、ＰＣＴ試験（１２１℃、２気圧）２００時間、２６０℃のはんだバス浸漬１０秒後においても変化がなく、良好な接続信頼性を示した。
【００１２】
実施例２
フェノキシ樹脂５０ｇと、ブチルアクリレート（４０部）、エチルアクリレート（３０部）、アクリロニトリル（３０部）及びグリシジルメタクリレート（３部）を共重合したアクリルゴム（分子量：８５万）１７５ｇを酢酸エチル５２５ｇに溶解し、３０％溶液を得た。ついで、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（エポキシ当量１８５）２７５ｇをこの溶液に加え、撹拌し、溶融シリカ（平均粒子径：０．５μｍ）を接着樹脂組成物１００重量部に対し６０重量部分散してフィルム塗工用溶液を得た。この溶液をセパレータ（シリコーン処理したポリエチレンテレフタレートフィルム、厚み４０μｍ）にロールコータで塗布し、１００℃、１０分乾燥し厚み２０μｍの接着フィルム１を作製した。この接着フィル１の溶融シリカを除いた接着樹脂組成物のみの動的粘弾性測定器で測定した４０℃の弾性率は、４００ＭＰａであった。接着フィルム１の作成において溶融シリカを分散する代わりにニッケル粒子（直径：３μｍ）を２ｖｏｌ％分散する以外は、同様な方法で厚み２０μｍの接着フィルム２を作製した。次に作製した接着フィルム１と接着フィルム２をラミネートしてフィルム状接着剤を得た。このフィルム状接着剤を用いて金バンプ（面積：８０μｍｘ８０μｍ、スペース３０μｍ、高さ：１５μｍ、バンプ数２８８）付きチップ（１０ｍｍｘ１０ｍｍ、厚み：０．５ｍｍ）とＮｉ／ＡｕめっきＣｕ回路プリント基板の接続を以下に示すように行った。このフィルム状接着剤の接着フィルム２（１２ｍｍｘ１２ｍｍ）をＮｉ／ＡｕめっきＣｕ回路プリント基板（電極高さ：２０μｍ、厚み：０．８ｍｍ）に８０℃、１０ｋｇｆ／ｃｍ ２ で貼りつけた後、セパレータを剥離し、接着フィルム１側にチップを対向し、チップのバンプとＮｉ／ＡｕめっきＣｕ回路プリント基板（厚み：０．８ｍｍ）の位置あわせを行った。ついで、１８０℃、５０ｇ／バンプ、２０秒の条件でチップ上方から加熱、加圧を行い、本接続を行った。本接続後の接続抵抗は、１バンプあたり最高で１８ｍΩ、平均で８ｍΩ、絶縁抵抗は１０の８乗Ω以上であり、これらの値は−５５〜１２５℃の熱衝撃試験１０００サイクル処理、ＰＣＴ試験（１２１℃、２気圧）２００時間、２６０℃のはんだバス浸漬１０秒後においても変化がなく、良好な接続信頼性を示した。
【００１３】
実施例３
フェェノキシ樹脂５０ｇ、ブチルアクリレート（４０部）、エチルアクリレート（３０部）、アクリロニトリル（３０部）及びグリシジルメタクリレート（３部）を共重合したアクリルゴム（分子量：８５万）１００ｇを酢酸エチル３５０ｇに溶解し、３０％溶液を得た。ついで、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（エポキシ当量１８５）３５０ｇをこの溶液に加え、撹拌し、溶融シリカ（平均粒子径：０．５μｍ）を接着樹脂組成物１００重量部に対し６０重量部を分散してフィルム塗工用溶液を得た。この溶液をセパレータ（シリコーン処理したポリエチレンテレフタレートフィルム、厚み４０μｍ）にロールコータで塗布し、１００℃１０分乾燥し厚み２５μｍの接着フィルム１を作製した。この接着フィルム１の溶融シリカを除いた接着樹脂組成物のみの動的粘弾性測定器で測定した４０℃の弾性率は、１０００ＭＰａであった。接着フィルム１の作成において溶融シリカを分散する代わりにさらにポリスチレン系核体（直径：５μｍ）の表面にＡｕ層を形成した導電粒子を５ｖｏｌ％分散する以外は、同様な方法で厚み２５μｍの接着フィルム２を作製した。次に作製した接着フィルム１と接着フィルム２をラミネートしてフィルム状接着剤を得た。このフィルム状接着剤を用いて金バンプ（面積：８０μｍｘ８０μｍ、スペース３０μｍ、高さ：１５μｍ、バンプ数２８８）付きチップ（１０ｍｍｘ１０ｍｍ、厚み：０．５ｍｍ）とＮｉ／ＡｕめっきＣｕ回路プリント基板の接続を以下に示すように行った。このフィルム状接着剤の接着フィルム２（１２ｍｍｘ１２ｍｍ）をＮｉ／ＡｕめっきＣｕ回路プリント基板（電極高さ：２０μｍ、厚み：０．８ｍｍ）に８０℃、１０ｋｇｆ／ｃｍ ２ で貼りつけた後、セパレータを剥離し、接着フィルム１側にチップを対向し、チップのバンプとＮｉ／ＡｕめっきＣｕ回路プリント基板（厚み：０．８ｍｍ）の位置あわせを行った。ついで、１８０℃、５０ｇ／バンプ、２０秒の条件でチップ上方から加熱、加圧を行い、本接続を行った。接続抵抗は、１バンプあたり最高で５ｍΩ、平均で１．５ｍΩ、絶縁抵抗は１０ ８ Ω以上であり、これらの値は−５５〜１２５℃の熱衝撃試験１０００サイクル処理、ＰＣＴ試験（１２１℃、２気圧）２００時間、２６０℃のはんだバス浸漬１０秒後においても変化がなく、良好な接続信頼性を示した。
【００１４】
実施例４
フェノキシ樹脂５０ｇと、ブチルアクリレート（４０部）、エチルアクリレート（３０部）、アクリロニトリル（３０部）及びグリシジルメタクリレート（３部）を共重合したアクリルゴム（分子量：８５万）１２５ｇを酢酸エチル４００ｇに溶解し、３０％溶液を得た。ついで、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（エポキシ当量１８５）３２５ｇをこの溶液に加え、撹拌し、溶融シリカ（平均粒子径：０．５μｍ）を接着樹脂組成物１００重量部に６０重量部を分散してフィルム塗工用溶液を得た。この溶液をセパレータ（シリコーン処理したポリエチレンテレフタレートフィルム、厚み２５μｍ）にロールコータで塗布し、１００℃１０分乾燥し厚み２５μｍの接着フィルム１５を作製した。この接着フィルム１の溶融シリカを除いた接着樹脂組成物のみの動的粘弾性測定器で測定した４０℃の弾性率は、８００ＭＰａであった。接着フィルム１の作成において溶融シリカを分散する代わりにニッケル粒子（直径：３μｍ）を２ｖｏｌ％分散する以外は、同様な方法で厚み２５μｍの接着フィルム２を作製した。次に作製した接着フィルム１と接着フィルム２をラミネートしてフィルム状接着剤を得た。このフィルム状接着剤を用いてバンプレスチップ（１０ｍｍｘ１０ｍｍ、厚み：０．５ｍｍ、パッド電極：Ａｌ、パッド径：１２０μｍ）と回路上にＮｉ／ＡｕめっきＣｕバンプ（直径：１００μｍ、スペース５０μｍ、高さ：１５μｍ、バンプ数２００）を形成したＮｉ／ＡｕめっきＣｕ回路プリント基板の接続を以下に示すように行った。このフィルム状接着剤の接着フィルム２（１２ｍｍｘ１２ｍｍ）をＮｉ／ＡｕめっきＣｕバンプ（直径：１００μｍ、スペース５０μｍ、高さ：１５μｍ、バンプ数２００）を形成したＮｉ／ＡｕめっきＣｕ回路プリント基板（電極高さ：２０μｍ、厚み：０．８ｍｍ）に８０℃、１０ｋｇｆ／ｃｍ ２ で貼りつけた後、セパレータを剥離し、接着フィルム１側にチップを対向し、チップのバンプとＮｉ／ＡｕめっきＣｕ回路プリント基板（厚み：０．８ｍｍ）の位置あわせを行った。ついで、１８０℃、５０ｇ／バンプ、２０秒の条件でチップ上方から加熱、加圧を行い、本接続を行った。本接続後の接続抵抗は、１バンプあたり最高で８ｍΩ、平均で４ｍΩ、絶縁抵抗は１０ ８ Ω以上であり、これらの値は−５５〜１２５℃の熱衝撃試験１０００サイクル処理、ＰＣＴ試験（１２１℃、２気圧）２００時間、２６０℃のはんだバス浸漬１０秒後においても変化がなく、良好な接続信頼性を示した。
【００１５】
【発明の効果】
本発明の回路板によれば、従来の回路板のように接着剤の熱膨張係数が大きくないため、チップとＡＣＦ界面でのストレスを緩和できる他、さらに接着樹脂組成物として４０℃での弾性率が１５０〜１５００ＭＰａである場合にはさらに接着樹脂組成物によって信頼性試験において生じるストレスを吸収できるため、信頼性試験後においても接続部での接続抵抗の増大や接着剤の剥離がなく、接続信頼性が大幅に向上する。また、本発明の回路板では、接着剤の熱膨張係数が小さくチップとＡＣＦ界面でのストレスを緩和できることから、チップの電極パッドに突起電極を設けた場合、温度サイクル試験下での突起電極の電極パッドからの剥離を大幅に低減できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit board obtained by, for example, fixing a semiconductor chip to a substrate with an adhesive by a flip chip mounting method and electrically connecting both electrodes.
[0002]
[Prior art]
In the field of semiconductor mounting, flip chip mounting, in which an IC chip is directly mounted on a printed circuit board or a flexible wiring board, has attracted attention as a new mounting form corresponding to cost reduction and high precision. As the flip chip mounting method, there are known a method in which solder bumps are provided on the terminals of the chip and solder connection is made, and a method in which electrical connection is made through a conductive adhesive. In these methods, there is a problem that when the stress based on the difference in thermal expansion coefficient between the chip to be connected and the substrate is exposed to various environments, it is generated at the connection interface and connection reliability is lowered. For this reason, a method of injecting an epoxy resin-based underfill material into the gap between the chip and the substrate is generally studied for the purpose of alleviating the stress at the connection interface. However, the underfill injection process complicates the process and is disadvantageous in terms of productivity and cost. Recently, flip-chip mounting using an anisotropic conductive adhesive having anisotropic conductivity and a sealing function has attracted attention from the viewpoint of process simplicity in order to solve such problems.
[0003]
[Problems to be solved by the invention]
However, when the chip is directly mounted on the substrate via the anisotropic conductive adhesive, stress based on the difference in thermal expansion coefficient between the chip and the substrate is generated in the connection portion under the temperature cycle test, and thermal shock test, PCT test, solder bath When a reliability test such as an immersion test is performed, there is a problem that an increase in connection resistance or peeling of the adhesive occurs. In addition, when a protruding electrode is formed on the connection terminal of the chip, stress based on the difference in thermal expansion coefficient between the chip and the substrate is concentrated in the reliability test, and the protruding electrode is peeled off from the chip electrode interface. However, there is a problem that poor conduction occurs.
The present invention provides a circuit board that does not increase connection resistance at the connection portion and does not peel off the adhesive, and greatly improves connection reliability.
[0004]
[Means for Solving the Problems]
The circuit board of the present invention includes a first circuit member having a first connection terminal and a second circuit member having a second connection terminal having a thermal expansion coefficient larger than that of the first circuit member. The connection terminal and the second connection terminal are arranged to face each other, an adhesive is interposed between the first connection terminal and the second connection terminal arranged to face each other, and the first and the second arrangement terminals are arranged to face each other by heating and pressing. A circuit board in which a connection terminal and a second connection terminal are electrically connected, wherein the adhesive contains 10 to 200 parts by weight of an inorganic filler in 100 parts by weight of the adhesive resin composition. 40 ° C. after curing of the adhesive composition of the adhesive layer 1 and / or the adhesive layer 2, which is a multilayer constituent adhesive comprising an adhesive layer 1 and an adhesive layer 2 mainly composed of the adhesive composition an elastic modulus 30~1500MPa in, the adhesive layer 1 is bonded to the first circuit member side And it is characterized in Rukoto.
[0005]
The elastic modulus at 40 ° C. after curing of the adhesive composition of the adhesive layer 1 and / or the adhesive layer 2 is preferably 30 to 1500 MPa, and the adhesive of the adhesive layer 1 and / or the adhesive layer 2 A composition containing an epoxy resin, an acrylic rubber, and a latent curing agent is used. The acrylic rubber preferably contains a glycidyl ether group in its molecule.
The average particle size of the inorganic filler is preferably 3 microns or less, and the adhesive composition of the adhesive layer 2 may contain 0.1 to 30% by volume of conductive particles. The adhesive composition of the adhesive layer 2 It is preferable that the average particle diameter of the conductive particles contained in is larger than the average particle diameter of the inorganic filler.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the circuit member used in the present invention include a semiconductor chip, a printed circuit board, and a flexible wiring board based on polyimide or polyester. On the electrode pad of the semiconductor chip or substrate, the bump formed by plating or the tip of the gold wire is melted with a torch or the like to form a gold ball, and after the ball is pressed onto the electrode pad, the wire is cut. Protruding electrodes such as wire bumps obtained in this way can be provided and used as connection terminals.
[0007]
As the adhesive resin composition used in the present invention, a mixture of an epoxy resin and a latent curing agent such as imidazole series, hydrazide series, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, dicyandiamide or the like is used. In order to relieve the stress based on the difference in thermal expansion coefficient of the circuit member, an adhesive resin composition having an elastic modulus at 40 ° C. after bonding of 30 to 1500 MPa is preferable. For example, as an adhesive resin composition capable of obtaining good fluidity and high connection reliability at the time of connection, epoxy resin and imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, dicyandiamide An adhesive in which an acrylic rubber is blended in a mixture of latent curing agents such as 40.degree. C. after bonding so that the elastic modulus is 30 to 1500 MPa. The elastic modulus of the cured adhesive film can be measured by using, for example, Rheospectra DVE-4 manufactured by Rheology Co., Ltd. (pull mode, temperature rising at 10 Hz, 5 ° C./min).
[0008]
Examples of the acrylic rubber used in the present invention include a polymer or copolymer having at least one of acrylic acid, acrylic acid ester, methacrylic acid ester or acrylonitrile as a monomer component. Among them, glycidyl acrylate containing a glycidyl ether group, A copolymer acrylic rubber containing glycidyl methacrylate is preferably used.
The molecular weight of these acrylic rubbers is preferably 200,000 or more from the viewpoint of increasing the cohesive strength of the adhesive. If the blending amount of acrylic rubber in the adhesive is 15 wt% or less, the elastic modulus at 40 ° C. after bonding exceeds 1500 MPa, and if it exceeds 40 wt%, the elastic modulus can be reduced, but melting at the time of connection Since the viscosity increases and the exclusion of the molten adhesive between the connection electrode boundaries or at the interface between the connection electrode and the conductive particles is reduced, it becomes impossible to ensure electrical continuity between the connection electrodes or between the connection electrodes and the conductive particles. For this reason, as an acrylic compounding quantity, 15-40 wt% is preferable. Since these acrylic rubbers blended in the adhesive have a peak temperature of dielectric loss tangent due to the rubber component in the vicinity of 40 to 60 ° C., the elastic modulus of the adhesive can be reduced. In addition, a thermoplastic resin such as a phenoxy resin can be blended in the adhesive in order to make film forming easier. In particular, the phenoxy resin is preferable because it has a similar structure to the epoxy resin and has characteristics such as excellent compatibility with the epoxy resin and excellent adhesion. For film formation, an adhesive composition composed of at least an epoxy resin, an acrylic rubber, a phenoxy resin, and a latent curing agent and a conductive particle are liquefied by dissolving or dispersing in an organic solvent, and applied onto a peelable substrate, and then a curing agent. This is done by removing the solvent below the activation temperature. The solvent used at this time is preferably an aromatic hydrocarbon-based and oxygen-containing mixed solvent because the solubility of the material is improved.
[0009]
The inorganic filler used in the present invention is not particularly limited, and examples thereof include powders such as fused silica, crystalline silica, calcium silicate, alumina, and calcium carbonate. The blending amount of the inorganic filler is 10 to 200 parts by weight with respect to 100 parts by weight of the adhesive resin composition, and the larger the blending amount is, the more effective it is to reduce the thermal expansion coefficient. Conductivity or poor conduction due to a decrease in the elimination of the adhesive at the connecting portion occurs . Because the amount is small and can not be reduced sufficiently thermal expansion coefficient, preferably 20 to 90 parts by weight. The average particle size is preferably 3 microns or less for the purpose of preventing poor conduction at the connection. Further, it is desirable to use a spherical filler for the purpose of preventing a decrease in resin fluidity at the time of connection and damage to the passivation film of the chip.
[0010]
In the adhesive of the present invention, conductive particles can be dispersed for the purpose of positively imparting anisotropic conductivity in order to absorb the height variation of the bumps of the chip and the circuit electrodes. In the present invention, the conductive particles are, for example, metal particles such as Au, Ni, Ag, Cu, W and solder or metal particles formed by plating or vapor deposition of a thin film such as gold or palladium on the surface of these metal particles, such as polystyrene. Conductive particles in which a polymer spherical core material is provided with a conductive layer such as Ni, Cu, Au, or solder can be used. The particle size needs to be smaller than the minimum distance between the electrodes on the substrate, and when there is a variation in the height of the electrodes, it is preferably larger than the variation in height, and preferably larger than the average particle size of the inorganic filler. 1 μm to 10 μm is preferable. The amount of conductive particles dispersed in the adhesive is 0.1 to 30% by volume, preferably 0.2 to 15% by volume.
[0011]
【Example】
Example 1
50 g of phenoxy resin and 125 g of acrylic rubber (molecular weight: 850,000) copolymerized with butyl acrylate (40 parts), ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidyl methacrylate (3 parts) are dissolved in 400 g of ethyl acetate. To obtain a 30% solution. Next, 325 g of a liquid epoxy (epoxy equivalent 185) containing a microcapsule type latent curing agent is added to this solution and stirred, and fused silica (average particle size: 0.5 μm) is added to 100 parts by weight of the resin adhesive composition. On the other hand, 40 parts by weight was dispersed to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater and dried at 100 ° C. for 10 minutes to produce an adhesive film 1 having a thickness of 25 μm. In addition, the 40 degreeC elastic modulus measured with the dynamic viscoelasticity measuring device only of the adhesive resin composition except the fused silica of this adhesive film 1 was 800 MPa. An adhesive film 2 having a thickness of 25 μm was produced in the same manner as in the production of the adhesive film 1 except that 2 vol% of nickel particles (diameter: 3 μm) were dispersed instead of dispersing the fused silica. Next, the produced adhesive film 1 and the adhesive film 2 were laminated to obtain a film adhesive. Using this film adhesive, the chip (10 mm x 10 mm, thickness: 0.5 mm) with gold bumps (area: 80 μm x 80 μm, space 30 μm, height: 15 μm, number of bumps 288) and Ni / Au plated Cu circuit printed circuit board are connected. The procedure was as follows. The adhesive film 2 (12 mm × 12 mm) of this film adhesive was applied to a Ni / Au plated Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 80 ° C. and 10 kgf / cm 2 , and then a separator was attached. The chip was peeled, the chip was opposed to the adhesive film 1 side, and the bumps of the chip and the Ni / Au plated Cu circuit printed circuit board (thickness: 0.8 mm) were aligned. Next, the main connection was made by heating and pressing from above the chip under the conditions of 180 ° C., 50 g / bump, and 20 seconds. The connection resistance after this connection is a maximum of 6 mΩ per bump, an average of 2 mΩ, and an insulation resistance of 10 8 Ω or more. These values are from the thermal shock test at −55 to 125 ° C., 1000 cycle treatment, PCT test (121 No change even after 10 seconds of immersion in a solder bath at 260 ° C. for 200 hours at 2 ° C., and good connection reliability was exhibited.
[0012]
Example 2
50 g of phenoxy resin and 175 g of acrylic rubber (molecular weight: 850,000) copolymerized with butyl acrylate (40 parts), ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidyl methacrylate (3 parts) are dissolved in 525 g of ethyl acetate. To obtain a 30% solution. Then, the microswitch liquid epoxy (epoxy equivalent weight 185) containing a capsule-type latent curing agent 275g was added to the solution, stirred, fused silica (average particle size: 0.5 [mu] m) to 100 parts by weight of the adhesive resin composition The solution for film coating was obtained by dispersing 60 parts by weight. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater, and dried at 100 ° C. for 10 minutes to produce an adhesive film 1 having a thickness of 20 μm. The elastic modulus at 40 ° C. measured by a dynamic viscoelasticity measuring instrument using only the adhesive resin composition excluding the fused silica of the adhesive fill 1 was 400 MPa. An adhesive film 2 having a thickness of 20 μm was prepared in the same manner as in the production of the adhesive film 1 except that 2 vol% of nickel particles (diameter: 3 μm) were dispersed instead of dispersing the fused silica. Next, the produced adhesive film 1 and the adhesive film 2 were laminated to obtain a film adhesive. Using this film adhesive, the chip (10 mm x 10 mm, thickness: 0.5 mm) with gold bumps (area: 80 μm x 80 μm, space 30 μm, height: 15 μm, number of bumps 288) and Ni / Au plated Cu circuit printed circuit board are connected. The procedure was as follows. The adhesive film 2 (12 mm × 12 mm) of this film adhesive was applied to a Ni / Au plated Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 80 ° C. and 10 kgf / cm 2 , and then a separator was attached. The chip was peeled, the chip was opposed to the adhesive film 1 side, and the bumps of the chip and the Ni / Au plated Cu circuit printed circuit board (thickness: 0.8 mm) were aligned. Next, the main connection was made by heating and pressing from above the chip under the conditions of 180 ° C., 50 g / bump, and 20 seconds. The connection resistance after this connection is a maximum of 18 mΩ per bump, an average of 8 mΩ, and the insulation resistance is 10 8 Ω or more. These values are from the thermal shock test at −55 to 125 ° C., 1000 cycle treatment, PCT test (121 ° C., 2 atm) No change even after 10 seconds of immersion in a solder bath at 260 ° C. for 200 hours, showing good connection reliability.
[0013]
Example 3
50 g of phenoxy resin, 100 g of acrylic rubber (molecular weight: 850,000) copolymerized with butyl acrylate (40 parts), ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidyl methacrylate (3 parts) were dissolved in 350 g of ethyl acetate. A 30% solution was obtained. Then, the microswitch liquid epoxy (epoxy equivalent weight 185) containing a capsule-type latent curing agent 350g was added to the solution, stirred, fused silica (average particle size: 0.5 [mu] m) to 100 parts by weight of the adhesive resin composition On the other hand, 60 parts by weight was dispersed to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater and dried at 100 ° C. for 10 minutes to produce an adhesive film 1 having a thickness of 25 μm. The elastic modulus at 40 ° C. measured by a dynamic viscoelasticity measuring device using only the adhesive resin composition excluding fused silica of the adhesive film 1 was 1000 MPa. Adhesive film having a thickness of 25 μm is produced in the same manner as in the production of the adhesive film 1 except that 5 vol% of conductive particles having an Au layer formed on the surface of a polystyrene core (diameter: 5 μm) are dispersed instead of dispersing the fused silica. 2 was produced. Next, the produced adhesive film 1 and the adhesive film 2 were laminated to obtain a film adhesive. Using this film adhesive, the chip (10 mm x 10 mm, thickness: 0.5 mm) with gold bumps (area: 80 μm x 80 μm, space 30 μm, height: 15 μm, number of bumps 288) and Ni / Au plated Cu circuit printed circuit board are connected. The procedure was as follows. The adhesive film 2 (12 mm × 12 mm) of this film adhesive was applied to a Ni / Au plated Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 80 ° C. and 10 kgf / cm 2 , and then a separator was attached. The chip was peeled, the chip was opposed to the adhesive film 1 side, and the bumps of the chip and the Ni / Au plated Cu circuit printed circuit board (thickness: 0.8 mm) were aligned. Next, the main connection was made by heating and pressing from above the chip under the conditions of 180 ° C., 50 g / bump, and 20 seconds. The connection resistance is 5 mΩ at the maximum per bump, 1.5 mΩ on average, and the insulation resistance is 10 8 Ω or more. These values are the thermal shock test 1000 cycle treatment at −55 to 125 ° C., the PCT test (121 ° C., 2 atmospheres) No change even after 200 seconds of immersion in a solder bath at 260 ° C. for 200 hours, showing good connection reliability.
[0014]
Example 4
50 g of phenoxy resin and 125 g of acrylic rubber (molecular weight: 850,000) copolymerized with butyl acrylate (40 parts), ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidyl methacrylate (3 parts) are dissolved in 400 g of ethyl acetate. To obtain a 30% solution. Then, the microswitch liquid epoxy (epoxy equivalent weight 185) containing a capsule-type latent curing agent 325g was added to the solution, stirred, fused silica (average particle size: 0.5 [mu] m) to 100 parts by weight of the adhesive resin composition 60 parts by weight were dispersed to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 25 μm) with a roll coater and dried at 100 ° C. for 10 minutes to produce an adhesive film 15 having a thickness of 25 μm. The elastic modulus at 40 ° C. measured by a dynamic viscoelasticity measuring device using only the adhesive resin composition excluding fused silica of the adhesive film 1 was 800 MPa. An adhesive film 2 having a thickness of 25 μm was produced in the same manner as in the production of the adhesive film 1 except that 2 vol% of nickel particles (diameter: 3 μm) were dispersed instead of dispersing the fused silica. Next, the produced adhesive film 1 and the adhesive film 2 were laminated to obtain a film adhesive. The film-like adhesive bar down pressing chip using (10 mm x 10 mm, thickness: 0.5 mm, the pad electrode: Al, pad diameter: 120 [mu] m) and Ni / Au plating on the circuit Cu bumps (diameter: 100 [mu] m, a space 50 [mu] m, high The connection of the Ni / Au-plated Cu circuit printed circuit board on which 15 μm and the number of bumps 200) were formed was performed as follows. This film adhesive adhesive film 2 (12 mm × 12 mm) is formed on a Ni / Au plated Cu circuit printed board (electrode height) on which Ni / Au plated Cu bumps (diameter: 100 μm, space 50 μm, height: 15 μm, number of bumps 200) are formed. (20 μm, thickness: 0.8 mm) at 80 ° C. and 10 kgf / cm 2 , then the separator is peeled off, the chip is opposed to the adhesive film 1 side, the chip bump and the Ni / Au plated Cu circuit print The substrate (thickness: 0.8 mm) was aligned. Next, the main connection was made by heating and pressing from above the chip under the conditions of 180 ° C., 50 g / bump, and 20 seconds. The connection resistance after this connection is a maximum of 8 mΩ per bump, an average of 4 mΩ, and an insulation resistance of 10 8 Ω or more, and these values are the thermal shock test at −55 to 125 ° C., 1000 cycle treatment, PCT test (121 No change even after 10 seconds of immersion in a solder bath at 260 ° C. for 200 hours at 2 ° C., and good connection reliability was exhibited.
[0015]
【The invention's effect】
According to the circuit board of the present invention, since the thermal expansion coefficient of the adhesive is not large as in the conventional circuit board, the stress at the interface between the chip and the ACF can be relieved, and further, the adhesive resin composition has elasticity at 40 ° C. When the rate is 150-1500 MPa, the stress generated in the reliability test can be absorbed by the adhesive resin composition, so there is no increase in connection resistance or peeling of the adhesive even after the reliability test, and the connection Reliability is greatly improved. In the circuit board of the present invention, since the thermal expansion coefficient of the adhesive is small and stress at the interface between the chip and the ACF can be relieved, when the protruding electrode is provided on the electrode pad of the chip, the protruding electrode under the temperature cycle test is used. Peeling from the electrode pad can be greatly reduced.
Claims (3)
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03098397A JP3925746B2 (en) | 1997-02-14 | 1997-02-14 | Circuit board |
| US12/549,909 US20090314533A1 (en) | 1997-02-14 | 2009-08-28 | Adhesive for bonding circuit members, circuit board and process for its production |
| US13/166,591 US8273458B2 (en) | 1997-02-14 | 2011-06-22 | Adhesive for bonding circuit members, circuit board and process for its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03098397A JP3925746B2 (en) | 1997-02-14 | 1997-02-14 | Circuit board |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10229264A JPH10229264A (en) | 1998-08-25 |
| JP3925746B2 true JP3925746B2 (en) | 2007-06-06 |
Family
ID=12318880
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03098397A Expired - Fee Related JP3925746B2 (en) | 1997-02-14 | 1997-02-14 | Circuit board |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3925746B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100290914B1 (en) * | 1999-03-05 | 2001-05-15 | 김영환 | structure for film in semiconductor package and method for fabricating the same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5001542A (en) * | 1988-12-05 | 1991-03-19 | Hitachi Chemical Company | Composition for circuit connection, method for connection using the same, and connected structure of semiconductor chips |
| JP3801666B2 (en) * | 1995-05-22 | 2006-07-26 | 日立化成工業株式会社 | Electrode connection method and connection member used therefor |
-
1997
- 1997-02-14 JP JP03098397A patent/JP3925746B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10229264A (en) | 1998-08-25 |
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