JP3603426B2

JP3603426B2 - Connection member for circuit

Info

Publication number: JP3603426B2
Application number: JP30266295A
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: 1995-11-21
Filing date: 1995-11-21
Publication date: 2004-12-22
Anticipated expiration: 2015-11-21
Also published as: JPH09143445A

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において、２つの回路基板同士の電極間に形成し、両電極を接続するのに好適な回路用接続部材に関するものである。
【０００２】
【従来の技術】
２つの回路基板同士を接着すると共に、これらの電極間に電気的導通を得る接着剤として、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。
その中でもエポキシ樹脂系接着剤は、高い接着強さが得られ、耐水性や耐熱性に優れること等から、電気・電子・建築・自動車・航空機等の各種用途に多用されている。特に一液型エポキシ樹脂系接着剤は、主剤と硬化剤との混合が不必要であり使用が簡便なことから、フィルム状、ペースト状、粉体状の形態で使用されている。この場合、エポキシ樹脂と硬化剤及び変性剤との多用な組み合わせにより、特定の性能を得ることが一般的であり、例えば、特開昭６２−１４１０８３号公報の試みが知られている。
この場合、接着剤中に導電性粒子を配合し、加圧により接着剤の厚み方向に電気的接続を得るもの（例えば特開昭５５−１０４００７号公報）と、導電性粒子を用いないで接続時の加圧により電極面の微細凹凸により電気的接続を得るもの（例えば特開昭６０−２６２４３０号公報）がある。
【０００３】
【発明が解決しようとする課題】
しかし、上記特開昭６２−１４１０８３号公報に示されるフィルム状接着剤
は、作業性に優れるものの耐熱性と耐湿性が不十分であるという欠点を有していた。
この理由は、短時間硬化性（速硬化性）と貯蔵安定性（保存性）の両立により良好な安定性を得ることを目的として、常温で不活性な触媒型硬化剤を用いているために、硬化に際して十分な反応が得られないためである。すなわち、耐熱性の尺度であるガラス転移点（Ｔｇ）は、最高１００℃近辺であり、半導体封止レベルで多用される、例えばプレッシャークッカー試験（ＰＣＴ、１２１℃−２ａｔｍ）といったより高温高湿の評価に耐性が不十分であった。なお、耐熱性用途に多用される硬化剤である酸無水物や芳香族アミン、及びポリフェノール等の重付加型の場合では、硬化に数時間以上と長時間が必要であり、作業性が不十分である。また、接着剤成分の溶融粘度の調整が不十分であると、接続部の仕上がりが悪くなり、接続信頼性に劣る等の不具合を生じる。
本発明の目的は、耐熱性と耐湿性、及び作業性に優れ、特に厳しい信頼性の要求される電気・電子用の回路用接続部材を提供することにある。
【０００４】
【課題を解決するための手段】
かかる目的は本発明によれば、下記（１）〜（４）の成分を必須とする接着剤成分と、導電性粒子よりなる回路用接続部材により達成される。
（１）ビスフェノールＦ型フェノキシ樹脂
（２）ナフタレン系エポキシ樹脂
（３）スチレン−無水マレイン酸共重合体樹脂
（４）潜在性硬化剤
【０００５】
【発明の実施の形態】
本発明に用いるビスフェノールＦ型フェノキシ樹脂について説明する。
ビスフェノールＦ型フェノキシ樹脂は、高速液体クロマトグラフィー（ＨＬＣ）から求められた分子量が１０，０００以上の高分子量エポキシ樹脂に相当し、エポキシ樹脂と同様に他にビスフェノールＡ型、ＡＤ型等の種類がある。これらはエポキシ樹脂と構造が類似していることから相溶性がよく、また接着性も良好な特徴を有する。分子量の大きい程フィルム形成性が容易に得られ、また接続時の流動性に影響する溶融粘度を広範囲に設定できる。平均分子量としては１０，０００〜８０，０００程度のものが溶融粘度や他の樹脂との相溶性等の点からより好ましい。これらの樹脂は、水酸基やカルボキシル基等の極性基等を含有すると、エポキシ樹脂との相溶性が向上し、均一な外観や特性を有するフィルムが得られることや、硬化時の反応促進による短時間硬化を得る点からも好ましい。配合量としては、フィルム形成性や硬化反応の促進の点から樹脂成分全体に対して２０〜８０重量％とするのが好ましい。また、溶融粘度調整等のために、ビスフェノールＡ型フェノキシ樹脂やアクリル樹脂を適宜混合してもよい。
【０００６】
本発明に用いるナフタレン系エポキシ樹脂は、１分子内に少なくとも１個以上のナフタレン環を含んだ骨格を有する高耐熱性樹脂であり、ナフトール系、ナフタレンジオール系等がある。ナフタレン系エポキシ樹脂は、他の高耐熱化用エポキシ樹脂と比較して諸物性に優れ、かつ接着剤組成物の硬化物のガラス転移温度（Ｔｇ）を向上させ、高温域での線膨張係数（α２）を低下させることが可能となるという点からより好ましい。
さらにこのナフタレン系エポキシ樹脂には必要に応じて、例えば、エピクロルヒドリンとビスフェノールＡやＦ、ＡＤ等から誘導されるビスフェノール型エポキシ樹脂、エピクロルヒドリンとフェノールノボラックやクレゾールノボラックから誘導されるエポキシノボラック樹脂やグリシジルアミン、グリシジルエステル、ビフェニル、脂環式、複素環式等の１分子内に２個以上のグリシジル基を有する各種のエポキシ化合物等を単独にあるいは２種以上を混合して用いることが可能である。上記した混合可能なエポキシ樹脂の中では、ビスフェノール型エポキシ樹脂が分子量の異なるグレードが広く入手可能で、接着性や反応性等を任意に設定できることから好ましい。
これらのエポキシ樹脂は、不純物イオン（Ｎａ^＋、Ｃｌ⁻等）や、加水分解性塩素等を３００ｐｐｍ以下に低減した高純度品を用いることがエレクトロンマイグレーション防止のために好ましい。
【０００７】
本発明に用いるスチレン系樹脂は、スチレンモノマーと１あるいはそれ以上の別のモノマー単位とのブロック共重合体であり、工業用に広く使用されている。中でもスチレンと無水マレイン酸の共重合体がベースとなっている樹脂は、耐熱性でありながら一般のスチレン系樹脂と同程度の流動性を示す。これらの樹脂は耐衝撃性、寸法安定性や成形加工性にも優れている。また、溶融粘度が比較的高いことから、他の接着用樹脂に混在させて用いた場合、溶融粘度の調整が行いやすい。これにより被接続体と接着硬化物の間に発生する微小な気泡を抑制することが可能であることから好ましい。
【０００８】
潜在性硬化剤としては、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、ジアミノマレオニトリル、メラミンおよびその誘導体、ポリアミンの塩、ジシアンジアミド等、及びこれらの変性物があり、これらは単独あるいは２種以上の混合体として使用できる。これらはアニオンまたはカチオン重合性の触媒型硬化剤であり、速硬化性を得やすく、また、化学当量的な考慮が少なくてよいことから好ましい。硬化剤としてはその他にポリアミン類、ポリメルカプタン、ポリフェノール、酸無水物等の重付加型の適用や前記触媒型硬化剤との併用も可能である。
アニオン重合型の触媒型硬化剤としては、第３アミン類やイミダゾール類が主として用いられる。第３アミン類やイミダゾール類を配合したエポキシ樹脂は、１６０〜２００℃程度の中温で数１０秒〜数時間程度の加熱により硬化するために可使時間（ポットライフ）が比較的長い。
カチオン重合型の触媒型硬化剤としては、エネルギー線照射により樹脂を硬化させる感光性オニウム塩、例えば、芳香族ジアゾニウム塩、芳香族スルホニウム塩等が主として用いられる。またエネルギー線照射以外に加熱によっても活性化してエポキシ樹脂を硬化させるものとして、脂肪族スルホニウム塩等がある。この種の硬化剤は速硬化性という特徴を有することから好ましい。
これらの硬化剤をポリウレタン、ポリエステル等の高分子物質や、Ｎｉ、Ｃｕ等の金属薄膜及びケイ酸カルシウム等の無機物で被覆してマイクロカプセル化したものは、可使時間が延長できるため好ましい。
【０００９】
上記で得た接着剤組成物中には、通常の添加剤等として例えば、充填剤、軟化剤、促進剤、老化防止剤、着色剤、難燃剤、チキソトロピック剤、カップリング剤及びフェノール樹脂やメラミン樹脂、イソシアネート類等の硬化剤等を含有することもできる。これらの中では、導電性粒子や酸化チタン、シリカ等の充填剤及びシラン、チタン、クロム、ジルコニウム、アルミニウム等の各系のカップリング剤が特に有効である。
【００１０】
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、これら及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り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、加熱加圧により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り使い分ける。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０．１〜１０体積％とするのがより好ましい。
カップリング剤としては、アミノ基やエポキシ基、およびイソシアネート基含有物が接着性の向上の点から好ましい。
【００１１】
本発明の接着剤組成物は一液型接着剤として、とりわけＩＣチップと基板との接着や電気回路相互の接着用のフィルム状接着剤として特に有用である。この場合例えば、上記で得た接着剤組成物を溶剤あるいはエマルジョンの場合の分散液等として液状化して、離形紙等の剥離性基材上に形成し、あるいは不織布等の基材に前記配合液を含浸させて剥離性基材上に形成し、硬化剤の活性温度以下で乾燥し、溶剤あるいは分散液等を除去すればよい。
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。ここに含酸素系溶剤のＳＰ値は８．１〜１０．７の範囲とすることが潜在性硬化剤の保護上好ましく、酢酸エステル類がより好ましい。また溶剤の沸点は１５０℃以下が適用できる。沸点が１５０℃を超すと乾燥に高温を要し、潜在性硬化剤の活性温度に近いことから潜在性の低下を招き、低温では乾燥時の作業性が低下する。このため沸点が６０〜１５０℃が好まし
く、７０〜１３０℃がより好ましい。
【００１２】
本発明で得た接続材料を用いた電極の接続について説明する。
この方法は、回路用接続部材を基板上の相対峙する電極間に配置し、加熱加圧により両電極の接触と基板間の接着を得る電極の接続方法である。電極を形成する基板としては、半導体、ガラス、セラミック等の無機質、ポリイミド、ポリカーボネート等の有機物、ガラス／エポキシ等のこれら複合の各組み合わせが適用できる。
【００１３】
本発明においては、ビスフェノールＦ型フェノキシ樹脂、ナフタレン系エポキシ樹脂、スチレン系樹脂及び潜在性硬化剤とを含有することにより、速硬化性と保存性の両立を得ながら、ガラス転移温度や弾性率低下温度の向上、線膨張係数の抑制、及び高温高湿性を得ることが可能である。この理由は、フェノキシ樹脂中の水酸基の存在がナフタレン系エポキシ樹脂の硬化反応を促進して速硬化性を可能とし、またフェノキシ樹脂、スチレン系樹脂が高分子量で粘度が比較的高いことから、常温域では潜在性硬化剤と接触しにくいことにより、良好な保存性が得られるためである。
フェノキシ樹脂は、分子鎖が長くエポキシ樹脂と構造が類似しており、高架橋密度の組成物中で可とう性材料として作用し、高靱性を付与するので高強度でありながらタフネスな組成物が得られる。
本発明に用いる回路用接触部材は、用いる接着剤がフェノキシ樹脂、ナフタレン系エポキシ樹脂、スチレン系樹脂及び潜在性硬化剤を含有し、溶剤の種類と沸点を特定し潜在性硬化剤の活性温度以下で乾燥するため、硬化剤の劣化がなく、安定した保存性が得られる。
【００１４】
【実施例】
以下、本発明を実施例に基づいて詳細に説明する。なお、それぞれの配合比は表１にまとめてある。
【００１５】
実施例１
ビスフェノールＦとエピクロルヒドリンから、ビスフェノールＦ型フェノキシ樹脂（平均分子量２０，０００）６０ｇを一般的方法により作製し、これ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の混合溶剤に溶解して、固形分４０％の溶液とした。
ナフタレン系エポキシ樹脂（ナフタレンジオール系エポキシ樹脂、大日本インキ化学工業株式会社製、商品名ＨＰ−４０３２、エポキシ当量１４９、加水分解性塩素１３０ｐｐｍ）２０ｇを重量比でトルエン／酢酸エチル＝５０／５０の混合溶剤に溶解して、固形分８０％の溶液とした。
スチレン系樹脂（スチレン−無水マレイン酸共重合樹脂、積水化成品工業株式会社製、商品名ダイラーク＃２５０、熱変形温度１１２℃）２０ｇをトルエンに溶解して、固形分４０％の溶液とした。
潜在性硬化剤は、ノバキュア３９４１ＨＰＳ（イミダゾール変性体を核とし、その表面をポリウレタンで被覆してなる平均粒径５μｍのマイクロカプセル型硬化剤を、液状ビスフェノールＦ型エポキシ樹脂中に分散してなるマスターバッチ型硬化剤、活性温度１２５℃、旭化成工業株式会社製商品名）を用いた。
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、さらに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１０μｍ、比重２．０の導電性粒子を作製した。
固形重量比で樹脂成分１００、潜在性硬化剤１００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、７５℃、１０分の熱風乾燥により接着剤層の厚みが２５μｍの回路用接続部材を得た。
【００１６】
参考例１、２
スチレン系樹脂をスチレン−無水マレイン酸共重合樹脂に代えて、スチレン−マレイミド共重合樹脂〔三菱化学株式会社製、商品名スーパーレックスＳＰＸ−Ｍ２５（熱変形温度１２５℃）（参考例１）、スーパーレックスＳＰＸ−Ｍ２８（同１２８℃）（参考例２）〕とし、これらの２０ｇを重量比でトルエン／酢酸エチル＝５０／５０の混合溶剤に溶解して固形分４０％の溶液とした他は、実施例１と同様にして回路用接続部材を得た。
【００１７】
実施例２
潜在性硬化剤をマイクロカプセル型硬化剤に代えて、Ｐ−アセトキシフェニルベンジルスルホニウム塩の５０重量％酢酸エチル溶液（三新化学工業株式会社製、商品名サンエイドＳＩ−６０Ｌ）とし、かつ固形重量比で樹脂成分１００に対して５となるように配合した他は、実施例１と同様にして回路用接続部材を得た。
【００１８】
実施例３
ビスフェノールＦ型フェノキシ樹脂の配合量を３０ｇとし、これにビスフェノールＡ型フェノキシ樹脂（ユニオンカーバイド株式会社製、商品名ＰＫＨＣ、平均分子量４５，０００）３０ｇを加えた他は、実施例１と同様にして回路用接続部材を得た。
【００１９】
実施例４
ナフタレン系エポキシ樹脂の配合量を１０ｇとし、これにビスフェノール型エポキシ樹脂（ビスフェノールＦ型エポキシ樹脂、油化シェルエポキシ株式会社製、商品名エピコート８２８、エポキシ当量１８４）１０ｇを加えた他は、実施例１と同様にして回路用接続部材を得た。
【００２０】
実施例５
導電性粒子を、平均粒径２μｍ、凝集粒径１０μｍのニッケル粒子に代えた他は、実施例１と同様にして回路用接続部材を得た。
【００２１】
実施例６
導電性粒子の配合量を７体積％とした他は、実施例１と同様にして回路用接続部材を得た。
【００２２】
比較例１
ナフタレン系エポキシ樹脂に代えて、ビスフェノール型エポキシ樹脂（エピコート８２８）とした他は、実施例１と同様にして回路用接続部材を得た。
【００２３】
比較例２
ビスフェノールＦ型フェノキシ樹脂、ナフタレン系エポキシ樹脂の配合量をそれぞれ７０ｇ、３０ｇとし、スチレン系樹脂を配合しない他は、実施例１と同様にして回路用接続部材を得た。
【００２４】
（熱機械分析）実施例１〜７、参考例１〜２、比較例１〜２で得た回路用接続部材の一部を、１７０℃で３０秒間シリコーン油上で加熱して硬化させて試料とし、これらを熱分析装置（株式会社マックサイエンス製、商品名ＴＭＡ４０００）により、引張荷重法、昇温速度１０℃／ｍｉｎで測定して、それぞれについてガラス転移温度（Ｔｇ／℃）及び線膨張係数（α／ｐｐｍ）を求めた。この結果を表２に示す。実施例１〜７の回路用接続部材のＴｇは、いずれも１２０〜１３５℃近辺であり、高温域におけるαは約１９０ｐｐｍであった。ナフタレン系エポキシ樹脂を含有していない比較例１の回路用接続部材のＴｇが１０６℃、αが約３８０ｐｐｍであることを考慮すると、実施例１〜７の回路用接続部材は高い耐熱性を有すると考えられる。
【００２５】
（広域動的粘弾性測定）上記硬化試料を用い、これらを広域動的粘弾性測定装置（株式会社レオロジ製、商品名ＤＶＥ−Ｖ４）により、引張荷重法、昇温速度５℃／ｍｉｎで測定して、それぞれについて弾性率低下温度（Ｅ’／℃）を求めた。この結果を表２に示す。実施例１〜７の回路用接続部材のＥ’が１１８〜１２５℃の範囲内にあるのに対し、比較例１では１００℃付近から弾性率が低下している。このことからもナフタレン系エポキシ樹脂が、回路用接続部材の高い耐熱性に寄与していると考えられる。
【００２６】
（回路の接続）
上述の回路用接続部材を用いて、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）同士を１７０℃、３ＭＰａで２０秒間加熱加圧して幅２ｍｍにわたり接続した。この時、予め一方のＦＰＣの上に回路用接続部材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ＦＰＣと接続した。
また、前述のＦＰＣと酸化インジウム（ＩＴＯ）の薄層を形成したガラス（表面抵抗２０Ω／□）とを１７０℃、３ＭＰａで２０秒間加熱加圧して幅２ｍｍにわたり接続した。この時、上記と同様にＩＴＯガラスに仮接続を行った。
【００２７】
（接続抵抗の測定）回路の接続後、上記接続部を含むＦＰＣの隣接回路間の抵抗値を、初期と、８５℃、８５％ＲＨの恒温恒湿槽中に５００時間保持した後にマルチメータで測定した。抵抗値は隣接回路間の抵抗１５０点の平均（ｘ＋３σ）で示した。これらの結果を表２に示す。実施例１で得られた回路用接続部材は良好な接続性を示した。また、初期の接続抵抗も低く、恒温恒湿試験後の抵抗の上昇もわずかであり、高い接続信頼性を示した。実施例２〜７の回路用接続部材も同様な結果が得られた。これに対して、ナフタレン系エポキシ樹脂に代えてビスフェノール型エポキシ樹脂を用いた比較例１は、硬化反応が不十分であるため接着状態が悪く、初期の接続抵抗がやや高くなった。またスチレン系樹脂を全く配合しなかった比較例２では、接続直後に回路中に微小な気泡が入るため、恒温恒湿試験後の抵抗値の上昇が著しかった。
【００２８】
【表１】

【００２９】
【表２】

【００３０】
【発明の効果】
以上詳述したように本発明によれば、耐熱性と耐湿性及び作業性に優れ、特に厳しい信頼性の要求される電気・電子用接着剤として好適な回路用接続部材を提供することが可能となった。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circuit connecting member which is formed between electrodes of two circuit boards in a liquid crystal panel or the like and is suitable for connecting both electrodes.
[0002]
[Prior art]
Adhesives that bond two circuit boards together and provide electrical conduction between these electrodes include styrene-based and polyester-based thermoplastics, and epoxy- and silicone-based thermosets. ing.
Among them, epoxy resin-based adhesives are frequently used in various applications such as electricity, electronics, architecture, automobiles, aircraft, and the like because of their high adhesive strength and excellent water resistance and heat resistance. In particular, the one-pack type epoxy resin-based adhesive is used in the form of a film, a paste, or a powder because it does not require mixing of a main agent and a curing agent and is easy to use. In this case, a specific performance is generally obtained by various combinations of an epoxy resin, a curing agent and a modifying agent, and for example, an attempt disclosed in Japanese Patent Application Laid-Open No. 62-141083 is known.
In this case, a conductive particle is mixed in the adhesive, and an electrical connection is obtained in the thickness direction of the adhesive by pressure (for example, JP-A-55-104007). There is a method in which electrical connection is obtained by fine irregularities on the electrode surface by pressurization at the time (for example, JP-A-60-262430).
[0003]
[Problems to be solved by the invention]
However, the film-like adhesive disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Sho 62-141083 is excellent in workability, but has a disadvantage that heat resistance and moisture resistance are insufficient.
The reason for this is that a catalytic curing agent that is inactive at room temperature is used for the purpose of obtaining good stability by achieving both short-time curing (rapid curing) and storage stability (preservability). This is because a sufficient reaction cannot be obtained during curing. That is, the glass transition point (Tg), which is a measure of heat resistance, is around 100 ° C. at the maximum, and is often used at a semiconductor encapsulation level, for example, at a higher temperature and higher humidity such as a pressure cooker test (PCT, 121 ° C.-2 atm). The evaluation was not sufficiently resistant. In addition, in the case of a polyaddition type such as an acid anhydride or an aromatic amine, which is a curing agent frequently used for heat-resistant applications, and polyphenols, the curing requires a long time of several hours or more, and the workability is insufficient. It is. In addition, if the adjustment of the melt viscosity of the adhesive component is insufficient, the finish of the connection portion is deteriorated, which causes problems such as poor connection reliability.
An object of the present invention is to provide a connection member for an electric / electronic circuit which is excellent in heat resistance, moisture resistance, and workability, and particularly requires strict reliability.
[0004]
[Means for Solving the Problems]
According to the present invention, such an object is achieved by a circuit connecting member comprising an adhesive component having the following components (1) to (4) as essential components and conductive particles.
(1) Bisphenol F type phenoxy resin (2) Naphthalene epoxy resin (3) Styrene- maleic anhydride copolymer resin (4) Latent curing agent
BEST MODE FOR CARRYING OUT THE INVENTION
The bisphenol F-type phenoxy resin used in the present invention will be described.
Bisphenol F type phenoxy resin is equivalent to a high molecular weight epoxy resin having a molecular weight of 10,000 or more determined by high performance liquid chromatography (HLC), and other types such as bisphenol A type and AD type are similar to epoxy resins. is there. Since these have similar structures to epoxy resins, they have good compatibility and good adhesiveness. The higher the molecular weight, the easier the film-forming properties can be obtained, and the melt viscosity which affects the fluidity at the time of connection can be set in a wide range. Those having an average molecular weight of about 10,000 to 80,000 are more preferable in view of melt viscosity, compatibility with other resins, and the like. When these resins contain a polar group such as a hydroxyl group or a carboxyl group, the compatibility with the epoxy resin is improved, and a film having a uniform appearance and properties can be obtained. It is preferable from the viewpoint of obtaining curing. The compounding amount is preferably 20 to 80% by weight based on the entire resin component from the viewpoint of promoting film formation and curing reaction. Further, bisphenol A-type phenoxy resin or acrylic resin may be appropriately mixed for adjusting the melt viscosity or the like.
[0006]
The naphthalene epoxy resin used in the present invention is a high heat-resistant resin having a skeleton containing at least one naphthalene ring in one molecule, and includes a naphthol resin and a naphthalene diol resin. Naphthalene-based epoxy resins are superior in various physical properties to other epoxy resins for increasing heat resistance, improve the glass transition temperature (Tg) of a cured product of the adhesive composition, and have a coefficient of linear expansion ( α2) is more preferable because it can reduce α2).
Further, the naphthalene-based epoxy resin may be optionally used, for example, a bisphenol-type epoxy resin derived from epichlorohydrin and bisphenol A, F, AD, etc .; , Glycidyl esters, biphenyls, alicyclic, heterocyclic and other epoxy compounds having two or more glycidyl groups in one molecule can be used alone or as a mixture of two or more. Among the above mixable epoxy resins, bisphenol type epoxy resins are preferred because grades having different molecular weights are widely available and adhesiveness, reactivity and the like can be arbitrarily set.
For these epoxy resins, it is preferable to use high-purity products in which impurity ions (Na ⁺ , Cl ^−, etc.), hydrolyzable chlorine and the like are reduced to 300 ppm or less, in order to prevent electron migration.
[0007]
The styrene resin used in the present invention is a block copolymer of a styrene monomer and one or more other monomer units, and is widely used in industry. Above all, a resin based on a copolymer of styrene and maleic anhydride exhibits fluidity comparable to that of a general styrene resin while having heat resistance. These resins are also excellent in impact resistance, dimensional stability and moldability. In addition, since the melt viscosity is relatively high, when mixed with another adhesive resin, the melt viscosity can be easily adjusted. This is preferable because it is possible to suppress minute bubbles generated between the connected body and the cured adhesive material.
[0008]
Examples of the latent curing agent include imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, diaminomaleonitrile, melamine and derivatives thereof, polyamine salts, dicyandiamide, and the like, and modified products thereof. These can be used alone or as a mixture of two or more. These are anionic or cationically polymerizable catalytic curing agents, and are preferable because they can easily obtain fast curing properties and require little consideration of chemical equivalents. As the curing agent, polyadditions of polyamines, polymercaptans, polyphenols, acid anhydrides, and the like can be applied, and the curing agent can be used in combination with the catalyst curing agent.
Tertiary amines and imidazoles are mainly used as anionic polymerization type catalyst-type curing agents. Epoxy resins containing tertiary amines or imidazoles have a relatively long pot life because they are cured by heating at a medium temperature of about 160 to 200 ° C. for about several tens of seconds to several hours.
As the cationic polymerization type catalyst-type curing agent, a photosensitive onium salt that cures a resin by irradiation with energy rays, for example, an aromatic diazonium salt, an aromatic sulfonium salt, or the like is mainly used. In addition, aliphatic sulfonium salts and the like can be activated by heating other than energy beam irradiation to cure the epoxy resin. This type of curing agent is preferred because it has the characteristic of fast curing.
A microcapsule obtained by coating these curing agents with a polymer substance such as polyurethane or polyester, a metal thin film such as Ni or Cu, or an inorganic substance such as calcium silicate can be used because the pot life can be extended.
[0009]
In the adhesive composition obtained above, for example, a filler, a softener, an accelerator, an antioxidant, a coloring agent, a flame retardant, a thixotropic agent, a coupling agent, a phenol resin, A curing agent such as a melamine resin and an isocyanate may be contained. Among these, conductive particles, fillers such as titanium oxide and silica, and coupling agents of various systems such as silane, titanium, chromium, zirconium, and aluminum are particularly effective.
[0010]
Examples of the conductive particles include metal particles such as Au, Ag, Ni, Cu, and solder, carbon, and the like. Even those formed by coating the above conductive layer on a non-conductive glass, ceramic, plastic, or the like by coating or the like. Good. In the case of using plastic as a nucleus or hot-melt metal particles, they are deformable by heating and pressing, so that the contact area with the electrode at the time of connection increases and reliability is improved, which is preferable. The conductive particles are used properly in a wide range of 0.1 to 30% by volume based on 100 volumes of the adhesive component. In order to prevent a short circuit in an adjacent circuit due to excessive conductive particles, the content is more preferably 0.1 to 10% by volume.
As the coupling agent, an amino group, an epoxy group, or an isocyanate group-containing material is preferable from the viewpoint of improving the adhesiveness.
[0011]
The adhesive composition of the present invention is particularly useful as a one-part adhesive, especially as a film adhesive for bonding an IC chip to a substrate or bonding electric circuits. In this case, for example, the adhesive composition obtained above is liquefied as a solvent or a dispersion in the case of an emulsion, and formed on a peelable substrate such as release paper, or mixed with a substrate such as a nonwoven fabric. The solution may be impregnated and formed on a peelable substrate, dried at a temperature lower than the activation temperature of the curing agent, and the solvent or the dispersion may be removed.
At this time, a mixed solvent of an aromatic hydrocarbon type and an oxygen-containing type is preferably used as the solvent for improving the solubility of the material. Here, the SP value of the oxygen-containing solvent is preferably in the range of 8.1 to 10.7 from the viewpoint of protection of the latent curing agent, and acetates are more preferable. Further, the boiling point of the solvent may be 150 ° C. or less. When the boiling point exceeds 150 ° C., a high temperature is required for drying, and since the temperature is close to the activation temperature of the latent curing agent, the potential is reduced. At a low temperature, workability during drying is reduced. For this reason, the boiling point is preferably from 60 to 150C, more preferably from 70 to 130C.
[0012]
The connection of the electrodes using the connection material obtained in the present invention will be described.
In this method, a circuit connecting member is disposed between opposing electrodes on a substrate, and the electrodes are connected by heating and pressing to obtain contact between the two electrodes and adhesion between the substrates. As the substrate on which the electrodes are formed, inorganic materials such as semiconductors, glass and ceramics, organic materials such as polyimide and polycarbonate, and combinations of these composite materials such as glass / epoxy can be applied.
[0013]
In the present invention, by containing a bisphenol F-type phenoxy resin, a naphthalene-based epoxy resin, a styrene-based resin, and a latent curing agent, the glass transition temperature and the elastic modulus are reduced while achieving both fast curing and storage stability. It is possible to improve the temperature, suppress the linear expansion coefficient, and obtain high temperature and high humidity. The reason for this is that the presence of hydroxyl groups in the phenoxy resin accelerates the curing reaction of the naphthalene-based epoxy resin and enables rapid curing, and the phenoxy resin and styrene-based resin have a high molecular weight and a relatively high viscosity, so that they can be used at room temperature. This is because, in the region, good preservability can be obtained by making it difficult to contact with the latent curing agent.
Phenoxy resin has a long molecular chain and similar structure to epoxy resin, acts as a flexible material in a composition with high cross-linking density, and imparts high toughness, resulting in a composition with high strength and toughness. Can be
The circuit contact member used in the present invention, the adhesive used contains a phenoxy resin, a naphthalene-based epoxy resin, a styrene-based resin and a latent curing agent, and specifies the type and boiling point of the solvent and the activation temperature of the latent curing agent or lower. , The curing agent is not deteriorated and stable storage stability is obtained.
[0014]
【Example】
Hereinafter, the present invention will be described in detail based on examples. In addition, each compounding ratio is put together in Table 1.
[0015]
Example 1
Bisphenol F and epichlorohydrin were used to prepare 60 g of a bisphenol F-type phenoxy resin (average molecular weight: 20,000) by a general method, and this was prepared at a weight ratio of toluene (boiling point 110.6 ° C., SP value 8.90) / ethyl acetate ( It was dissolved in a mixed solvent having a boiling point of 77.1 ° C. and an SP value of 9.10) = 50/50 to obtain a solution having a solid content of 40%.
20 g of a naphthalene-based epoxy resin (naphthalene diol-based epoxy resin, manufactured by Dainippon Ink and Chemicals, Inc., trade name: HP-4032, epoxy equivalent: 149, hydrolyzable chlorine: 130 ppm) in a weight ratio of toluene / ethyl acetate = 50/50. It was dissolved in a mixed solvent to obtain a solution having a solid content of 80%.
20 g of a styrene-based resin (styrene-maleic anhydride copolymer resin, manufactured by Sekisui Chemical Co., Ltd., trade name: Dylark # 250, heat deformation temperature: 112 ° C.) was dissolved in toluene to obtain a solution having a solid content of 40%.
The latent curing agent is a master made by dispersing a microcapsule-type curing agent having an average particle diameter of 5 μm, which is obtained by coating Novacur 3941 HPS (imidazole modified nucleus and its surface with polyurethane) in a liquid bisphenol F epoxy resin. A batch-type curing agent, an activation temperature of 125 ° C., trade name, manufactured by Asahi Kasei Kogyo Co., Ltd.) was used.
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 further provided outside the nickel layer. The conductive particles have an average particle size of 10 μm and a specific gravity of 2.0. Was prepared.
The resin component 100 and the latent curing agent 100 were mixed at a solid weight ratio, and 3% by volume of conductive particles were further dispersed and applied to a fluororesin film having a thickness of 80 μm using a coating apparatus. By drying with hot air at 10 ° C. for 10 minutes, a circuit connecting member having an adhesive layer thickness of 25 μm was obtained.
[0016]
Reference Examples 1 and 2
A styrene-maleimide copolymer resin [manufactured by Mitsubishi Chemical Corporation, trade name: SUPERLEX SPX-M25 (heat deformation temperature: 125 ° C.) ( Reference Example 1 )) instead of a styrene-maleic anhydride copolymer resin instead of a styrene resin. Rex SPX-M28 (same as above, 128 ° C.) ( Reference Example 2 )], except that 20 g of these were dissolved in a mixed solvent of toluene / ethyl acetate = 50/50 at a weight ratio to obtain a solution having a solid content of 40%. A circuit connecting member was obtained in the same manner as in Example 1.
[0017]
Example 2
A 50% by weight solution of P-acetoxyphenylbenzylsulfonium salt in ethyl acetate (manufactured by Sanshin Chemical Industry Co., Ltd., trade name: SunAid SI-60L) was used instead of the latent curing agent with the microcapsule type curing agent, and the solid weight ratio A circuit connecting member was obtained in the same manner as in Example 1, except that the amount was changed to 5 with respect to the resin component 100.
[0018]
Example 3
The same procedure as in Example 1 was carried out except that the blending amount of the bisphenol F-type phenoxy resin was 30 g, and 30 g of a bisphenol A-type phenoxy resin (manufactured by Union Carbide Co., Ltd., trade name: PKHC, average molecular weight: 45,000) was added. A circuit connecting member was obtained.
[0019]
Example 4
Except that the compounding amount of the naphthalene-based epoxy resin was 10 g, and 10 g of a bisphenol-type epoxy resin (bisphenol F-type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 828, epoxy equivalent: 184) was added thereto, In the same manner as in Example 1, a circuit connecting member was obtained.
[0020]
Example 5
A circuit connecting member was obtained in the same manner as in Example 1, except that the conductive particles were replaced with nickel particles having an average particle size of 2 μm and an aggregate particle size of 10 μm.
[0021]
Example 6
A circuit connecting member was obtained in the same manner as in Example 1, except that the blending amount of the conductive particles was 7% by volume.
[0022]
Comparative Example 1
A circuit connecting member was obtained in the same manner as in Example 1 except that a bisphenol-type epoxy resin (Epicoat 828) was used instead of the naphthalene-based epoxy resin.
[0023]
Comparative Example 2
A circuit connecting member was obtained in the same manner as in Example 1 except that the amounts of the bisphenol F-type phenoxy resin and the naphthalene-based epoxy resin were 70 g and 30 g, respectively, and the styrene-based resin was not blended.
[0024]
(Thermo-mechanical analysis) A part of the circuit connecting members obtained in Examples 1 to 7, Reference Examples 1 and 2 and Comparative Examples 1 and 2 was cured by heating on silicone oil at 170 ° C. for 30 seconds. These were measured with a thermal analyzer (trade name: TMA4000, manufactured by Mac Science Co., Ltd.) at a tensile load method at a temperature rising rate of 10 ° C./min, and for each, the glass transition temperature (Tg / ° C.) and the linear expansion coefficient were measured. (Α / ppm) was determined. Table 2 shows the results. The Tg of each of the circuit connecting members of Examples 1 to 7 was around 120 to 135 ° C., and α in the high temperature range was about 190 ppm. Considering that the Tg of the circuit connecting member of Comparative Example 1 containing no naphthalene-based epoxy resin is 106 ° C. and α is about 380 ppm, the circuit connecting members of Examples 1 to 7 have high heat resistance. It is thought that.
[0025]
(Measurement of dynamic viscoelasticity over a wide area) Using the cured samples described above, these were measured with a wide area dynamic viscoelasticity measurement apparatus (trade name: DVE-V4, manufactured by Rheology Co., Ltd.) at a tensile load method at a temperature rising rate of 5 ° C / min. Then, the elastic modulus lowering temperature (E ′ / ° C.) was determined for each. Table 2 shows the results. While E ′ of the circuit connecting members of Examples 1 to 7 is in the range of 118 to 125 ° C., in Comparative Example 1, the elastic modulus decreases from around 100 ° C. This also suggests that the naphthalene epoxy resin contributes to the high heat resistance of the circuit connecting member.
[0026]
(Circuit connection)
Using the above-described circuit connecting member, flexible circuit boards (FPCs) each having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm were heated and pressed at 170 ° C. and 3 MPa for 20 seconds, and were connected over a width of 2 mm. . At this time, after bonding the adhesive surface of the circuit connecting member on one of the FPCs in advance, the connection is temporarily made by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. Connected to one FPC.
Further, the above-mentioned FPC and glass (surface resistance 20Ω / □) on which a thin layer of indium oxide (ITO) was formed were heated and pressed at 170 ° C. and 3 MPa for 20 seconds, and were connected over a width of 2 mm. At this time, a temporary connection was made to the ITO glass in the same manner as described above.
[0027]
(Measurement of connection resistance) After connection of the circuit, the resistance value between the adjacent circuits of the FPC including the connection portion was initially and for 500 hours kept in a thermo-hygrostat at 85 ° C. and 85% RH, and then measured with a multimeter. It was measured. The resistance value was shown as an average (x + 3σ) of 150 points of resistance between adjacent circuits. Table 2 shows the results. The circuit connecting member obtained in Example 1 showed good connectivity. In addition, the initial connection resistance was low, and the rise in resistance after the constant temperature and humidity test was slight, indicating high connection reliability. Similar results were obtained for the circuit connecting members of Examples 2 to 7 . On the other hand, Comparative Example 1, in which a bisphenol-type epoxy resin was used instead of the naphthalene-based epoxy resin, had a poor curing state due to insufficient curing reaction, and the initial connection resistance was slightly higher. In Comparative Example 2 in which no styrene-based resin was blended at all, microbubbles entered the circuit immediately after connection, so that the resistance value after the constant temperature and humidity test was remarkably increased.
[0028]
[Table 1]

[0029]
[Table 2]

[0030]
【The invention's effect】
As described in detail above, according to the present invention, it is possible to provide a circuit connecting member that is excellent in heat resistance, moisture resistance, and workability, and is particularly suitable as an electrical / electronic adhesive requiring strict reliability. It became.

Claims

A circuit connecting member comprising: an adhesive component having the following components (1) to (4) as essential components; and conductive particles .
(1) Bisphenol F type phenoxy resin (2) Naphthalene epoxy resin (3) Styrene- maleic anhydride copolymer resin (4) Latent curing agent

The circuit connecting member according to claim 1, wherein the bisphenol F-type phenoxy resin has a molecular weight (MW) of 10,000 or more.

3. The circuit connecting member according to claim 1, wherein the naphthalene epoxy resin is a naphthalene diol epoxy resin.

The circuit connecting member according to any one of claims 1 to 3 , wherein the latent curing agent is an onium salt.

The circuit connecting member according to any one of claims 1 to 4 , wherein the conductive particles have an average particle size of 2 to 18 µm.

The circuit connecting member according to any one of claims 1 to 5 , wherein the content of the conductive particles is 0.1 to 10% by volume based on 100% by volume of the adhesive composition.

The circuit connecting member according to any one of claims 1 to 6 , wherein the shape is a film shape.