JP2004035781A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing semiconductor, having excellent moldability, flame-retardancy, high-temperature storage stability, moisture-resistance reliability and solder reflow resistance and produced without using a halogen-based flame-retardant and an antimony compound. <P>SOLUTION: The epoxy resin composition for sealing semiconductor contains (A) an epoxy resin, (B) a phenolic resin, (C) a cure accelerator consisting of an addition product of a phosphine compound expressed by general formula (1) and a quinone compound expressed by general formula (2), and (D) an inorganic filler as essential components. The epoxy resin (A) and/or the phenolic resin (B) contain one or more kinds of resins having a phenolaralkyl structure having a phenylene skeleton, a phenolaralkyl structure having a biphenylene skeleton or a naphtholaralkyl structure having a phenylene skeleton and containing 10-75 wt.% binuclear material in the resin. <P>COPYRIGHT: (C)2004,JPO

Description

（式中、Ｒ１〜Ｒ３は置換又は非置換の炭素数１〜１２のアルキル基もしくは置換又は非置換の炭素数６〜１２のアリール基を示し、全て同一でも異なっていてもよい。）
【０００９】
【化８】

（式中、Ｒ４〜Ｒ６は水素原子又は炭素数１〜１２の炭化水素を示し、全て同一でも異なっていてもよく、Ｒ４とＲ５が結合して環状構造となっていてもよい。）
【００１０】
【化９】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数、ｂは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘは水素又はグリシジル基。）
【００１１】
【化１０】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘは水素又はグリシジル基。）
【００１２】
【化１１】

（式中、Ｒは炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ｂは１又は２。ｎは平均値で、０又は１〜１０の正数。Ｘは水素又はグリシジル基。）
【００１３】
［２］　（Ｃ）一般式（１）で示されるホスフィン化合物と一般式（２）で示されるキノン化合物との付加物である硬化促進剤が、式（６）である第［１］項記載の半導体封止用エポキシ樹脂組成物、
【化１２】

【００１４】
［３］　全エポキシ樹脂組成物中に含有される臭素原子及びアンチモン原子が、それぞれ０．１重量％未満である第［１］項〜第［２］項記載の半導体封止用エポキシ樹脂組成物、
［４］　第［１］項〜第［３］項記載のいずれかの半導体封止用エポキシ樹脂組成物を用いて半導体素子を封止してなることを特徴とする半導体装置、
である。
【００１５】
【発明の実施の形態】
本発明に用いるエポキシ樹脂である一般式（３）〜（５）で示されるエポキシ樹脂は、樹脂骨格が疎水性を示すので硬化物が低吸湿性を示すと共に、硬化物の架橋点間距離が長くなるため半田リフロー温度での弾性率が低い特長を有し、このため発生する応力が低く密着性にも優れるため、耐半田リフロー性が良好であり好ましい。更に、樹脂骨格に占める芳香族環含有率が高いために、樹脂そのものの難燃性も高く、難燃剤の配合量を低く抑えることができるという特長を有する。
本発明では二核体含有量が１０〜７５重量％のエポキシ樹脂を用いるが、二核体とは一般式（３）〜（５）においてｎ＝１の構造をいう。二核体量はＧＰＣ（Ｇｅｌ　Ｐｅｒｍｅａｔｉｏｎ　Ｃｈｒｏｍａｔｏｇｒａｐｈｙ）法によりポリスチレン換算して求めた値である。即ち、東ソー（株）製ＧＰＣカラム（Ｇ１０００Ｈ×Ｌ：１本、Ｇ２０００Ｈ×Ｌ：２本、Ｇ３０００Ｈ×Ｌ：１本）を用い、流量１．０ｃｍ^３／６０秒、溶出溶媒としてテトラヒドロフラン、カラム温度４０℃の条件で示差屈折計を検出器に用いて測定しポリスチレン換算して求めた。二核体含有量が下限値を下回るとエポキシ樹脂の粘度が高くなりすぎ、成形時の樹脂組成物の流動性が劣り、より一層の低吸湿化のための無機充填材の高充填化が困難となる。二核体含有量が上限値を越えるとエポキシ樹脂の粘度が低くなりすぎ、樹脂の取扱いの点で問題がある。また、架橋密度の低下により熱時強度が低下し、耐半田リフロー性が低下するという問題がある。
【００１６】
【化１３】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数、ｂは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘはグリシジル基。）
【００１７】
【化１４】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘはグリシジル基。）
【００１８】
【化１５】

（式中、Ｒは炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ｂは１又は２。ｎは平均値で、０又は１〜１０の正数、Ｘはグリシジル基。）
【００１９】
また、これら本発明で用いる一般式（３）〜（５）で示されるエポキシ樹脂は、他のエポキシ樹脂と併用することができる。併用するエポキシ樹脂としては１分子内にエポキシ基を２個以上有するモノマー、オリゴマー、ポリマー全般を言い、その分子量、分子構造を特に限定するものではないが、特に、ビフェニル型エポキシ樹脂、ビスフェノール型エポキシ樹脂、スチルベン型エポキシ樹脂、フェノールノボラック型エポキシ樹脂、クレゾールノボラック型エポキシ樹脂、トリフェノールメタン型エポキシ樹脂、アルキル変性トリフェノールメタン型エポキシ樹脂、トリアジン核含有エポキシ樹脂、ジシクロペンタジエン変性フェノール型エポキシ樹脂、ナフトール型エポキシ樹脂等が挙げられる。
【００２０】
本発明に用いるフェノール樹脂である一般式（３）〜（５）で示されるフェノール樹脂は、樹脂骨格が疎水性を示すので硬化物が低吸湿性を示すと共に、硬化物の架橋点間距離が長くなるため半田リフロー温度での弾性率が低い特長を有し、このため発生する応力が低く密着性にも優れるため、耐半田リフロー性が良好であり好ましい。またこれらのフェノール樹脂は樹脂骨格に占める芳香族環含有率が高いために、樹脂そのものの難燃性も高く、難燃剤の配合量を低く抑えることができるという特長も有する。
本発明では二核体含有量が１０〜７５重量％のフェノール樹脂を用いる。二核体とは一般式（３）〜（５）においてｎ＝１の構造をいう。二核体含有量が下限値を下回るとフェノール樹脂の粘度が高くなりすぎ、成形時の樹脂組成物の流動性が劣り、より一層の低吸湿化のための無機充填材の高充填化が困難となる。二核体含有量は前記したＧＰＣ法により測定した。二核体含有量が上限値を越えるとフェノール樹脂の粘度が低くなりすぎ、樹脂の取扱いの点で問題となる。また架橋密度の低下により熱時強度が低下し、耐半田リフロー性が低下するという問題がある。
【００２１】
【化１６】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数、ｂは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘは水素。）
【００２２】
【化１７】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘは水素。）
【００２３】
【化１８】

（式中、Ｒは炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ｂは１又は２。ｎは平均値で、０又は１〜１０の正数。Ｘは水素。）
【００２４】
また、これら本発明で用いる一般式（３）〜（５）で示されるフェノール樹脂は他のフェノール樹脂と併用することができる。併用するフェノール樹脂としては、１分子内にフェノール性水酸基を２個以上有するモノマー、オリゴマー、ポリマー全般を言い、その分子量、分子構造を特に限定するものではないが、例えば、フェノールノボラック樹脂、クレゾールノボラック樹脂、ジシクロペンタジエン変性フェノール樹脂、テルペン変性フェノール樹脂、トリフェノールメタン型樹脂等が挙げられる。
【００２５】
本発明におけるエポキシ樹脂ならびにフェノール樹脂に関しては、エポキシ樹脂、及び／又はフェノール樹脂が一般式（３）〜（５）で示される構造を１種類以上含有することが必須である。これらの樹脂を１種類以上含有することにより、良好な耐半田リフロー性や難燃性を発現させることができ、性能良好な半導体封止樹脂組成物を得ることを可能とする。本発明においては、一般式（３）〜（５）で示される構造を有するエポキシ樹脂、及び／又はフェノール樹脂の樹脂全体に対する配合比率は、４０重量％以上が好ましく、更に好ましくは６０重量％以上である。また、全エポキシ樹脂のエポキシ基数と全フェノール樹脂のフェノール性水酸基数の比（エポキシ基数／フェノール性水酸基数）が０．８〜１．３の範囲にあるのが好ましい。比が下限値を下回ると硬化性と硬化物の耐熱性が低下し、吸湿率が増大するという問題があり、上限値を越えると硬化物の耐熱性と耐燃性が低下するという問題がある。
【００２６】
【化１９】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数、ｂは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘは水素又はグリシジル基。）
【００２７】
【化２０】

（式中、Ｒは水素又は炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ａは０〜４の整数。ｎは平均値で、１〜１０の正数。Ｘは水素又はグリシジル基。）
【００２８】
【化２１】

（式中、Ｒは炭素数１〜４のアルキル基を表し、互いに同一もしくは異なっていてもよい。ｂは１又は２。ｎは平均値で、０又は１〜１０の正数。Ｘは水素又はグリシジル基。）
【００２９】
本発明に用いる硬化促進剤は、一般式（１）で示されるホスフィン化合物と一般式（２）で示されるキノン化合物との付加物であり、特に好ましくは式（６）で示される１，４−ベンゾキノンとトリフェニルホスフィンを付加させた硬化促進剤が望ましい。式（６）で示される硬化促進剤を用いたエポキシ樹脂組成物は、硬化が速くなり成形性が向上し、硬化物は低吸湿率となり、熱時強度が向上するため良好な耐半田リフロー性が得られる。
【００３０】
【化２２】

（式中、Ｒ１〜Ｒ３は置換又は非置換の炭素数１〜１２のアルキル基もしくは置換又は非置換の炭素数６〜１２のアリール基を示し、全て同一でも異なっていてもよい。）
【００３１】
【化２３】

（式中、Ｒ４〜Ｒ６は水素原子又は炭素数１〜１２の炭化水素を示し、全て同一でも異なっていてもよく、Ｒ４とＲ５が結合して環状構造となっていてもよい。）
【００３２】
【化２４】

【００３３】
本発明に用いる硬化促進剤の好ましい配合量は各エポキシ樹脂組成物の配合内容により異なるが、成形時の流動性が低下し未充填や金線変形が起こったり、成形時の硬化性低下や離型性低下が起こったりしない範囲内での使用が望ましい。また、一般式（１）で示されるホスフィン化合物と一般式（２）で示されるキノン化合物との付加物である硬化促進剤は、前記硬化促進剤が全硬化促進剤中３０重量％以上となる範囲で他の硬化促進剤と併用しても構わない。３０重量％未満だと本発明における効果が充分に発現されない恐れがある。併用する硬化促進剤としては、エポキシ基とフェノール性水酸基との硬化反応を促進させるものであればよく、一般に封止材料に使用するものを用いることができる。例えば１，８−ジアザビシクロ（５，４，０）ウンデセン−７、トリフェニルホスフィン、２−メチルイミダゾール、テトラフェニルホスホニウム・テトラフェニルボレート等が挙げられる。
【００３４】
本発明に用いる無機充填材としては、一般に封止材料に使用されているものを使用することができる。例えば、溶融シリカ、結晶シリカ、タルク、アルミナ、窒化珪素等が挙げられ、これらは単独でも混合して用いても差し支えない。無機充填材の配合量としては、成形性と耐半田リフロー性のバランスから、全エポキシ樹脂組成物中に６０〜９５重量％含有することが好ましく、より好ましくは７５〜９５重量％である。下限値を下回ると吸湿率の上昇に伴い耐半田リフロー性が低下し、上限値を越えるとワイヤースィープ及びパッドシフト等の成形性の問題が生じ、好ましくない。
【００３５】
また本発明のエポキシ樹脂組成物は、臭素原子、アンチモン原子の含有量が、それぞれ全エポキシ樹脂組成物中に０．１重量％未満であることが好ましく、完全に含まれない方がより好ましい。臭素原子、アンチモン原子のいずれかが０．１重量％以上だと、高温下に放置したときに半導体装置の抵抗値が時間と共に増大し、最終的には半導体素子の金線が断線する不良が発生する可能性がある。また、環境保護の観点からも、臭素原子、アンチモン原子のそれぞれの含有量が０．１重量％未満で、極力含有されていないことが望ましい。
本発明のエポキシ樹脂組成物は、（Ａ）〜（Ｄ）成分を必須成分し、これ以外に必要に応じてシランカップリング剤、カーボンブラック等の着色剤、天然ワックス、合成ワックス等の離型剤、及びシリコーンオイル、ゴム等の低応力添加剤等の種々の添加剤を適宜配合しても差し支えない。
また、本発明のエポキシ樹脂組成物は、（Ａ）〜（Ｄ）成分、及びその他の添加剤等をミキサー等を用いて充分に均一に混合した後、更に熱ロール又はニーダー等で溶融混練し、冷却後粉砕して得られる。
【００３６】
本発明のエポキシ樹脂組成物を用いて、半導体素子等の各種の電子部品を封止する方法は、トランスファーモールド、コンプレッションモールド、インジェクションモールド等の従来からの成形方法で硬化成形すればよい。本発明のエポキシ樹脂組成物を用いて半導体装置を製造する方法は、公知の方法を用いることができる。
【００３７】
【実施例】
以下、本発明を実施例で具体的に説明するが、本発明はこれらに限定されるものではない。配合割合は重量部とする。
＜実施例１＞

【化２５】

【００３８】

【化２６】

【００３９】

【化２７】

をミキサーを用いて常温で混合した後、表面温度が９０℃と４５℃の２本ロールを用いて混練し、冷却後粉砕して、エポキシ樹脂組成物を得た。得られたエポキシ樹脂組成物を以下の方法で評価した。結果を表１に示す。
【００４０】
＜評価方法＞
スパイラルフロー：ＥＭＭＩ−１−６６に準じたスパイラルフロー測定用の金型を用いて、金型温度１７５℃、注入圧力６．９ＭＰａ、硬化時間１２０秒で測定した。単位はｃｍ。
硬化性：低圧トランスファー成形機を用いて、金型温度１７５℃、注入圧力６．９ＭＰａ、硬化時間１２０秒で成形した。金型が開いて１０秒後のランナーの表面硬度をバコール硬度計＃９３５で測定した。バコール硬度は硬化性の指標であり、数値が大きい方が硬化性が良好である。
吸湿率：低圧トランスファー成形機を用いて、金型温度１７５℃、注入圧力７．９ＭＰａ、硬化時間１２０秒で、直径５０ｍｍ、厚さ３ｍｍの円板を成形し、１７５℃、８時間で後硬化し、８５℃、相対湿度８５％の環境下で１６８時間放置し、重量変化を測定して吸湿率を求めた。単位は重量％。
熱時曲げ強度：低圧トランスファー成形機を用いて、金型温度１７５℃、注入圧力９．８ＭＰａ、硬化時間１２０秒で、長さ８０ｍｍ、幅１０ｍｍ、厚さ４ｍｍの試験片を成形し、１７５℃、８時間で後硬化し、ＪＩＳ　Ｋ　６９１１に準じて２４０℃での曲げ強度を測定した。単位はＮ／ｍｍ^２。
難燃性：低圧トランスファー成形機を用いて金型温度１７５℃、注入圧力９．８ＭＰａ、硬化時間１２０秒で、試験片（１２７ｍｍ×１２．７ｍｍで厚みは３．２ｍｍ）を成形し、１７５℃、８時間で後硬化した後、ＵＬ−９４垂直法に準じてΣＦ、Ｆｍａｘを測定し、難燃性を判定した。
【００４１】
耐半田リフロー性：低圧トランスファー成形機を用いて、金型温度１７５℃、注入圧力８．３ＭＰａ、硬化時間１２０秒で、８０ｐＱＦＰ（２ｍｍ厚、チップサイズ９．０ｍｍ×９．０ｍｍ）を２０個成形し、１７５℃、８時間で後硬化し、８５℃、相対湿度８５％で１６８時間放置し、その後２４０℃の半田槽に１０秒間浸漬した。顕微鏡で観察し、クラック発生率［（クラック発生率）＝｛（外部クラック発生パッケージ数）／（全パッケージ数）｝×１００］を求めた。単位は％。また、半導体素子とエポキシ樹脂組成物硬化物との界面の剥離面積を超音波探傷装置を用いて測定し、剥離率［（剥離率）＝｛（剥離面積）／（半導体素子面積）｝×１００］を求めた。単位は％。
高温保管特性：低圧トランスファー成形機を用いて金型温度１７５℃、圧力９．８ＭＰａ、硬化時間１２０秒で、１６ｐＤＩＰ（チップサイズ３．０ｍｍ×３．５ｍｍ）を成形し、１７５℃、８時間で後硬化した後、高温保管試験（１８５℃、１０００時間）を行い、配線間の電気抵抗値が初期値に対し２０％増加したパッケージを不良と判定した。１５個のパッケージ中の不良なパッケージ個数の率（不良率）を百分率で示した。単位は％。
臭素原子、アンチモン原子含有量：圧力５．９ＭＰａで直径４０ｍｍ、厚さ５〜７ｍｍに圧縮成形し、得られた成形品を蛍光Ｘ線分析装置を用いて、全エポキシ樹脂組成物中の臭素原子、アンチモン原子の含有量を定量した。単位は重量％。
【００４２】
＜実施例２〜１０、比較例１〜４＞
実施例１と同様にしてエポキシ樹脂組成物を得て、実施例１と同様にして評価を行った。結果を表１に示す。
実施例１以外で用いた原材料を下記に示す。
【００４３】
エポキシ樹脂２：式（９）で示されるエポキシ樹脂（軟化点５４℃、エポキシ当量２１７ｇ／ｅｑ．、二核体含有量１７重量％）
【化２８】

【００４４】
エポキシ樹脂３：式（１０）で示されるエポキシ樹脂（軟化点６０℃、エポキシ当量２６８ｇ／ｅｑ．、二核体含有量２９重量％）
【化２９】

【００４５】
エポキシ樹脂４：式（１１）で示されるエポキシ樹脂（軟化点８１℃、エポキシ当量２６３ｇ／ｅｑ．、二核体含有量４３重量％）
【化３０】

【００４６】
エポキシ樹脂５：ビフェニル型エポキシ樹脂（ジャパンエポキシレジン（株）製、ＹＸ４０００ＨＫ、融点１０５℃、エポキシ当量１９０ｇ／ｅｑ．）
【００４７】
フェノール樹脂２：式（１２）で示されるフェノール樹脂（軟化点６５℃、水酸基当量２２１ｇ／ｅｑ．、二核体含有量５１重量％）
【化３１】

【００４８】
フェノール樹脂３：式（１３）で示されるフェノール樹脂（軟化点８４℃、水酸基当量２０５ｇ／ｅｑ．、二核体含有量４８重量％）
【化３２】

【００４９】
フェノール樹脂４：フェノールノボラック樹脂（軟化点８０℃、水酸基当量１０３ｇ／ｅｑ．）
【００５０】
エポキシ樹脂６：式（１４）の構造を主成分とするエポキシ樹脂（軟化点８１℃、エポキシ当量２６９ｇ／ｅｑ．、二核体含有量６重量％）
【化３３】

【００５１】
フェノール樹脂５：式（１５）で示されるフェノール樹脂（軟化点８６℃、水酸基当量２３３ｇ／ｅｑ．、二核体含有量８重量％）
【化３４】

【００５２】
臭素化ビスフェノールＡ型エポキシ樹脂（軟化点６２℃、エポキシ当量３６５ｇ／ｅｑ．、臭素原子含有率４８重量％）
三酸化二アンチモン
硬化促進剤２：式（１６）で示される硬化促進剤
【化３５】

【００５３】
硬化促進剤３：式（１７）で示される硬化促進剤
【化３６】

【００５４】
硬化促進剤４：１，８−ジアザビシクロ（５，４，０）ウンデセン−７
【００５５】
【表１】

【００５６】
【発明の効果】
本発明に従うと、ハロゲン系難燃剤、及びアンチモン化合物を使用しないで、成形性に優れた半導体封止用エポキシ樹脂組成物が得られ、これを用いた半導体装置は、難燃性、高温保管特性、耐湿信頼性、及び耐半田リフロー性に優れる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an epoxy resin composition for semiconductor encapsulation, which does not use a halogen-based flame retardant or an antimony compound and has excellent solder reflow resistance, flame retardancy, and high-temperature storage characteristics, and a semiconductor device.
[0002]
[Prior art]
Conventionally, electronic components such as diodes, transistors, and integrated circuits have been mainly sealed with an epoxy resin composition. These epoxy resin compositions generally contain a bromine atom-containing flame retardant and an antimony compound such as antimony trioxide in order to impart flame retardancy. However, when a semiconductor device sealed with an epoxy resin composition containing a halogen-based flame retardant and an antimony compound is stored at a high temperature, a thermally decomposed halide is liberated from these flame retardant components, and a bonding portion of the semiconductor element is bonded. Is known to corrode the semiconductor device and impair the reliability of the semiconductor device. As described above, the corrosion resistance of the bonding portion (bonding pad portion) of the semiconductor element after the semiconductor device is stored at a high temperature (for example, 185 ° C.) is called a high-temperature storage characteristic, and the high-temperature storage characteristic is improved. Examples of the method include a method of using diantimony pentoxide without using a bromine atom-containing flame retardant (Japanese Patent Application Laid-Open No. 55-146950), and a method of combining antimony oxide with an organic phosphine (Japanese Patent Application Laid-Open No. 61-1986). JP-A-53321) has been proposed, and the effect has been confirmed. However, some types of epoxy resin compositions have been unsatisfactory with respect to recent high levels of high-temperature storage characteristics required for semiconductor devices. Under these circumstances, there is a growing awareness of environmental protection worldwide, and there is an increasing demand for epoxy resin compositions having flame retardancy without using halogen-based flame retardants or antimony compounds.
[0003]
To meet these requirements, various flame retardants have been studied. For example, metal hydroxides such as aluminum hydroxide and magnesium hydroxide have been actively studied, but if they are not blended in a large amount, the flame-retardant effect is not exhibited, and sufficient flame retardancy is obtained. If the amount is too high, the curability may be reduced. Also, in the current situation where surface mounting of semiconductor devices is becoming common, a semiconductor device that has absorbed moisture is exposed to high temperatures during soldering, and cracks occur in the package due to the explosive stress of vaporized water vapor, The occurrence of peeling at the interface between the element or the lead frame and the semiconductor encapsulating material causes defects that greatly impair electrical reliability, and prevention of these defects, that is, improvement of solder reflow resistance has become a major issue. I have. Furthermore, in response to recent environmental problems, there has been a trend toward eliminating lead contained in solder used for mounting semiconductor devices, and it is believed that the temperature of solder reflow processing will increase with this trend. It is believed that the required solder reflow resistance will be more severe.
[0004]
In order to improve the solder reflow resistance, the epoxy resin composition for semiconductor encapsulation is compounded with a large amount of an inorganic filler, so that the semiconductor device obtained by using the compound has low moisture absorption, low thermal expansion, and high strength. We are trying to make it. For this reason, low-viscosity epoxy resins and crystalline epoxy resins that are crystalline at room temperature but exhibit extremely low viscosity above the melting point are used. In general, a method of preventing a decrease in fluidity during molding of a resin composition, or a method of using an epoxy resin or a phenol resin in which a resin skeleton itself is hydrophobic and a cured product also exhibits low moisture absorption is used. Have been.
[0005]
Crystalline epoxy resins, hydrophobic epoxy resins, and phenolic resins have low glass transition temperatures, which tend to reduce high-temperature storage characteristics.To improve this, systems that do not use halogen-based flame retardants or antimony compounds It has been demanded.
In addition, crystalline epoxy resins have low viscosity because of their low viscosity, and hydrophobic epoxy resins and phenolic resins have a molecular structure with a long distance between cross-linking points. It is difficult to use a flame retardant that inhibits the curing of the epoxy resin in order to improve the mold release property and increase the productivity.
That is, there is a need for an epoxy resin composition that maintains flame retardancy without using a halogen-based flame retardant and an antimony compound, has excellent moldability, solder reflow resistance, and high-temperature storage characteristics.
[0006]
[Problems to be solved by the invention]
The present invention provides an epoxy resin composition for semiconductor encapsulation which is excellent in moldability, flame retardancy, solder reflow resistance and high-temperature storage characteristics without using a halogen-based flame retardant and an antimony compound, and a semiconductor using the same. It is to provide a semiconductor device in which an element is sealed.
[0007]
[Means for Solving the Problems]
The present invention uses a halogen-based flame retardant, and a crystalline epoxy resin, a hydrophobic epoxy resin, and a phenol resin that can be highly filled with an inorganic filler in order to achieve both flame retardancy and solder reflow resistance without using an antimony compound. Used as a resin component, it was achieved through intensive studies, such as selection of an appropriate effect accelerator, in order to solve the problems of reduced high-temperature storage properties and curability and mold release properties during molding due to its use. The abstract is
[1] (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator which is an adduct of a phosphine compound represented by the general formula (1) and a quinone compound represented by the general formula (2), D) an inorganic filler as an essential component, (A) an epoxy resin and / or (B) a phenol resin having a structure represented by the general formulas (3) to (5), and a binuclear content of the resin. An epoxy resin composition for semiconductor encapsulation containing at least one kind of resin of 10 to 75% by weight,
[0008]
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(In the formula, R1 to R3 represent a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, all of which may be the same or different.)
[0009]
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(In the formula, R4 to R6 each represent a hydrogen atom or a hydrocarbon having 1 to 12 carbon atoms, all of which may be the same or different, and R4 and R5 may combine to form a cyclic structure.)
[0010]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 4, b is an integer of 0 to 4. n is an average value. A positive number of 1 to 10. X is hydrogen or a glycidyl group.)
[0011]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other. A is an integer of 0 to 4. n is an average number and a positive number of 1 to 10. X Is hydrogen or a glycidyl group.)
[0012]
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(Wherein, R represents an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. B is 1 or 2. n is an average number and is a positive number of 0 or 1 to 10. X is hydrogen. Or a glycidyl group.)
[0013]
[2] The description of the above item [1], wherein (C) a curing accelerator which is an adduct of the phosphine compound represented by the general formula (1) and the quinone compound represented by the general formula (2) is represented by the following formula (6). Epoxy resin composition for semiconductor encapsulation,
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[0014]
[3] The epoxy resin composition for semiconductor encapsulation according to any one of [1] to [2], wherein bromine atoms and antimony atoms contained in all the epoxy resin compositions are each less than 0.1% by weight. ,
[4] A semiconductor device obtained by sealing a semiconductor element using the epoxy resin composition for semiconductor sealing according to any one of [1] to [3].
It is.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The epoxy resin represented by the general formulas (3) to (5), which is the epoxy resin used in the present invention, has a resin skeleton that is hydrophobic, so that the cured product has low hygroscopicity, and the distance between the crosslinking points of the cured product is low. Since it is longer, it has the characteristic of having a low elastic modulus at the solder reflow temperature, and hence it has low stress generated and excellent adhesion, so that solder reflow resistance is good and preferable. Further, since the aromatic ring content in the resin skeleton is high, the flame retardancy of the resin itself is high, and the compounding amount of the flame retardant can be kept low.
In the present invention, an epoxy resin having a binuclear content of 10 to 75% by weight is used, and the binuclear refers to a structure of general formulas (3) to (5) where n = 1. The binucleate amount is a value determined in terms of polystyrene by a GPC (Gel Permeation Chromatography) method. That, manufactured by Tosoh Corporation GPC column (G1000H × L: 1 present, G2000H × L: 2 present, G3000H × L: 1 present) using a flow rate of 1.0 cm ^3/60 sec, tetrahydrofuran as eluent, column temperature The measurement was performed using a differential refractometer at 40 ° C. as a detector, and the value was determined in terms of polystyrene. If the binuclear content is below the lower limit, the viscosity of the epoxy resin becomes too high, the fluidity of the resin composition during molding is inferior, and it is difficult to increase the filling of the inorganic filler to further reduce moisture absorption. It becomes. If the binuclear content exceeds the upper limit, the viscosity of the epoxy resin becomes too low, and there is a problem in handling the resin. Further, there is a problem that the strength at the time of heat is reduced due to the decrease of the crosslink density, and the solder reflow resistance is reduced.
[0016]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 4, b is an integer of 0 to 4. n is an average value. A positive number of 1 to 10. X is a glycidyl group.)
[0017]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other. A is an integer of 0 to 4. n is an average number and a positive number of 1 to 10. X Is a glycidyl group.)
[0018]
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(In the formula, R represents an alkyl group having 1 to 4 carbon atoms, which may be the same or different. B is 1 or 2. n is an average value, a positive number of 0 or 1 to 10, and X is glycidyl. Base.)
[0019]
The epoxy resins represented by the general formulas (3) to (5) used in the present invention can be used in combination with other epoxy resins. The epoxy resin used in combination refers to all monomers, oligomers and polymers having two or more epoxy groups in one molecule, and the molecular weight and molecular structure are not particularly limited. In particular, biphenyl type epoxy resin and bisphenol type epoxy resin are used. Resin, stilbene type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin, triazine nucleus containing epoxy resin, dicyclopentadiene modified phenol type epoxy resin, Naphthol type epoxy resin and the like can be mentioned.
[0020]
The phenolic resin represented by the general formulas (3) to (5), which is a phenolic resin used in the present invention, has a resin skeleton exhibiting a hydrophobic property, so that the cured product exhibits low hygroscopicity and the distance between crosslinking points of the cured product is low. Since it is longer, it has the characteristic of having a low elastic modulus at the solder reflow temperature, and hence it has low stress generated and excellent adhesion, so that solder reflow resistance is good and preferable. In addition, since these phenolic resins have a high aromatic ring content in the resin skeleton, the resins themselves also have high flame retardancy and have the advantage that the amount of the flame retardant can be reduced.
In the present invention, a phenol resin having a binuclear content of 10 to 75% by weight is used. Binuclear refers to a structure where n = 1 in the general formulas (3) to (5). If the binuclear content is below the lower limit, the viscosity of the phenolic resin becomes too high, the fluidity of the resin composition at the time of molding is poor, and it is difficult to highly fill the inorganic filler for further lowering moisture absorption. It becomes. The binuclear content was measured by the GPC method described above. If the binuclear content exceeds the upper limit, the viscosity of the phenolic resin becomes too low, which poses a problem in handling the resin. In addition, there is a problem that the strength at the time of heat decreases due to the decrease in the crosslink density, and the solder reflow resistance decreases.
[0021]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 4, b is an integer of 0 to 4. n is an average value. (A positive number of 1 to 10. X is hydrogen.)
[0022]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other. A is an integer of 0 to 4. n is an average number and a positive number of 1 to 10. X Is hydrogen.)
[0023]
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(Wherein, R represents an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. B is 1 or 2. n is an average number and is a positive number of 0 or 1 to 10. X is hydrogen. .)
[0024]
The phenolic resins represented by the general formulas (3) to (5) used in the present invention can be used in combination with other phenolic resins. The phenolic resin used in combination refers to all monomers, oligomers, and polymers having two or more phenolic hydroxyl groups in one molecule, and the molecular weight and molecular structure are not particularly limited. For example, phenol novolak resin, cresol novolak Resins, dicyclopentadiene-modified phenolic resins, terpene-modified phenolic resins, triphenolmethane-type resins, and the like.
[0025]
Regarding the epoxy resin and the phenolic resin in the present invention, it is essential that the epoxy resin and / or the phenolic resin contain at least one kind of the structures represented by the general formulas (3) to (5). By containing one or more of these resins, good solder reflow resistance and flame retardancy can be exhibited, and a semiconductor sealing resin composition having good performance can be obtained. In the present invention, the mixing ratio of the epoxy resin and / or phenol resin having the structure represented by the general formulas (3) to (5) to the whole resin is preferably 40% by weight or more, more preferably 60% by weight or more. It is. Further, the ratio of the number of epoxy groups of all epoxy resins to the number of phenolic hydroxyl groups of all phenolic resins (the number of epoxy groups / the number of phenolic hydroxyl groups) is preferably in the range of 0.8 to 1.3. If the ratio is less than the lower limit, there is a problem that the curability and heat resistance of the cured product decrease, and the moisture absorption rate increases. If the ratio exceeds the upper limit, there is a problem that the heat resistance and flame resistance of the cured product decrease.
[0026]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 4, b is an integer of 0 to 4. n is an average value. A positive number of 1 to 10. X is hydrogen or a glycidyl group.)
[0027]
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(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other. A is an integer of 0 to 4. n is an average number and a positive number of 1 to 10. X Is hydrogen or a glycidyl group.)
[0028]
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(Wherein, R represents an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. B is 1 or 2. n is an average number and is a positive number of 0 or 1 to 10. X is hydrogen. Or a glycidyl group.)
[0029]
The curing accelerator used in the present invention is an adduct of a phosphine compound represented by the general formula (1) and a quinone compound represented by the general formula (2), and particularly preferably 1,4 represented by the formula (6). -A curing accelerator to which benzoquinone and triphenylphosphine are added is desirable. The epoxy resin composition using the curing accelerator represented by the formula (6) cures quickly and improves moldability, and the cured product has a low moisture absorption rate, and has an improved strength when heated, so that good solder reflow resistance is obtained. Is obtained.
[0030]
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(In the formula, R1 to R3 represent a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, all of which may be the same or different.)
[0031]
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(In the formula, R4 to R6 each represent a hydrogen atom or a hydrocarbon having 1 to 12 carbon atoms, all of which may be the same or different, and R4 and R5 may combine to form a cyclic structure.)
[0032]
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[0033]
The preferred amount of the curing accelerator used in the present invention varies depending on the content of each epoxy resin composition.However, the fluidity during molding decreases, unfilling or gold wire deformation occurs, or the curability decreases during molding or separation. It is desirable to use it within a range in which the reduction in moldability does not occur. Further, in the curing accelerator which is an adduct of the phosphine compound represented by the general formula (1) and the quinone compound represented by the general formula (2), the curing accelerator accounts for 30% by weight or more of the total curing accelerator. You may use together with another hardening accelerator in the range. If it is less than 30% by weight, the effect of the present invention may not be sufficiently exhibited. As the curing accelerator to be used in combination, any one may be used as long as it promotes the curing reaction between the epoxy group and the phenolic hydroxyl group, and those generally used for a sealing material can be used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, 2-methylimidazole, tetraphenylphosphonium tetraphenylborate and the like can be mentioned.
[0034]
As the inorganic filler used in the present invention, those generally used for a sealing material can be used. For example, fused silica, crystalline silica, talc, alumina, silicon nitride and the like can be mentioned, and these may be used alone or in combination. The amount of the inorganic filler is preferably 60 to 95% by weight, more preferably 75 to 95% by weight in the total epoxy resin composition in view of the balance between moldability and solder reflow resistance. Below the lower limit, the solder reflow resistance decreases as the moisture absorption rate increases, and above the upper limit, moldability problems such as wire sweep and pad shift occur, which is not preferred.
[0035]
The epoxy resin composition of the present invention preferably has a bromine atom content and an antimony atom content of less than 0.1% by weight in the total epoxy resin composition, and more preferably does not completely contain the same. If either the bromine atom or the antimony atom is 0.1% by weight or more, the resistance value of the semiconductor device increases with time when left at high temperature, and eventually the failure of the gold wire of the semiconductor element to occur is caused. Can occur. Also, from the viewpoint of environmental protection, it is desirable that the content of each of the bromine atom and the antimony atom is less than 0.1% by weight, and that the content is as low as possible.
The epoxy resin composition of the present invention comprises the components (A) to (D) as essential components, and optionally releases a silane coupling agent, a coloring agent such as carbon black, a natural wax, a synthetic wax, and the like. Various additives such as low-stress additives such as silicone oil and rubber may be appropriately compounded.
Further, the epoxy resin composition of the present invention is prepared by sufficiently mixing the components (A) to (D) and other additives uniformly using a mixer or the like, and then further melt-kneading with a hot roll or a kneader. , After cooling and pulverized.
[0036]
The method of sealing various electronic components such as semiconductor elements using the epoxy resin composition of the present invention may be performed by curing and molding by a conventional molding method such as transfer molding, compression molding, and injection molding. As a method for manufacturing a semiconductor device using the epoxy resin composition of the present invention, a known method can be used.
[0037]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. The mixing ratio is by weight.
<Example 1>

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[0038]

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[0039]

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Was mixed at room temperature using a mixer, kneaded using two rolls having a surface temperature of 90 ° C. and 45 ° C., cooled and pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following method. Table 1 shows the results.
[0040]
<Evaluation method>
Spiral flow: Measured using a mold for spiral flow measurement according to EMMI-1-66 at a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 120 seconds. The unit is cm.
Curability: Molding was performed using a low-pressure transfer molding machine at a mold temperature of 175 ° C, an injection pressure of 6.9 MPa, and a curing time of 120 seconds. Ten seconds after the mold was opened, the surface hardness of the runner was measured with a Bacol hardness meter # 935. Bacol hardness is an index of curability, and the larger the value, the better the curability.
Moisture absorption: A low pressure transfer molding machine was used to mold a disk having a diameter of 50 mm and a thickness of 3 mm at a mold temperature of 175 ° C., an injection pressure of 7.9 MPa and a curing time of 120 seconds, and was post-cured at 175 ° C. for 8 hours. Then, it was left in an environment of 85 ° C. and a relative humidity of 85% for 168 hours, and a change in weight was measured to determine a moisture absorption rate. The unit is% by weight.
Bending strength under heat: Using a low-pressure transfer molding machine, a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm was molded at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds, and the temperature was 175 ° C. After curing for 8 hours, the flexural strength at 240 ° C. was measured according to JIS K 6911. The unit is N / mm ² .
Flame retardancy: A test piece (127 mm x 12.7 mm and 3.2 mm thick) was molded using a low-pressure transfer molding machine at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 120 seconds. After post-curing for 8 hours, ΔF and Fmax were measured according to the UL-94 vertical method to determine the flame retardancy.
[0041]
Solder reflow resistance: Using a low-pressure transfer molding machine, 20 pieces of 80pQFP (2 mm thick, chip size 9.0 mm × 9.0 mm) were molded at a mold temperature of 175 ° C., an injection pressure of 8.3 MPa, and a curing time of 120 seconds. Then, it was post-cured at 175 ° C. for 8 hours, left standing at 85 ° C. and a relative humidity of 85% for 168 hours, and then immersed in a 240 ° C. solder bath for 10 seconds. Observation with a microscope was performed to determine the crack occurrence rate [(crack occurrence rate) = {(number of external crack occurrence packages) / (total number of packages)} × 100]. Units%. The peeling area at the interface between the semiconductor element and the cured epoxy resin composition was measured using an ultrasonic flaw detector, and the peeling rate [(peeling rate) = {(peeling area) / (semiconductor element area)} × 100 ]. Units%.
High-temperature storage characteristics: Using a low-pressure transfer molding machine, a 16pDIP (chip size: 3.0 mm × 3.5 mm) was molded at a mold temperature of 175 ° C., a pressure of 9.8 MPa, and a curing time of 120 seconds. After post-curing, a high-temperature storage test (185 ° C., 1000 hours) was performed, and a package in which the electric resistance between wirings increased by 20% from the initial value was determined to be defective. The percentage of defective packages out of the 15 packages (defective rate) is shown in percentage. Units%.
Content of bromine atom and antimony atom: Compression molded to a diameter of 40 mm and a thickness of 5 to 7 mm at a pressure of 5.9 MPa, and the obtained molded product was analyzed by a fluorescent X-ray analyzer to obtain a bromine atom in all epoxy resin compositions. And the content of antimony atoms were quantified. The unit is% by weight.
[0042]
<Examples 2 to 10, Comparative Examples 1 to 4>
An epoxy resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 1 shows the results.
The raw materials used in other than Example 1 are shown below.
[0043]
Epoxy resin 2: epoxy resin represented by the formula (9) (softening point: 54 ° C., epoxy equivalent: 217 g / eq., Binuclear content: 17% by weight)
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[0044]
Epoxy resin 3: epoxy resin represented by the formula (10) (softening point: 60 ° C., epoxy equivalent: 268 g / eq., Binuclear content: 29% by weight)
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[0045]
Epoxy resin 4: epoxy resin represented by the formula (11) (softening point: 81 ° C., epoxy equivalent: 263 g / eq., Binuclear substance content: 43% by weight)
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[0046]
Epoxy resin 5: Biphenyl type epoxy resin (YX4000HK, manufactured by Japan Epoxy Resin Co., Ltd., melting point 105 ° C, epoxy equivalent 190g / eq.)
[0047]
Phenol resin 2: a phenol resin represented by the formula (12) (softening point: 65 ° C., hydroxyl equivalent: 221 g / eq., Binucleate content: 51% by weight)
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[0048]
Phenol resin 3: a phenol resin represented by the formula (13) (softening point: 84 ° C., hydroxyl equivalent: 205 g / eq., Binucleate content: 48% by weight)
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[0049]
Phenol resin 4: phenol novolak resin (softening point: 80 ° C., hydroxyl equivalent: 103 g / eq.)
[0050]
Epoxy resin 6: an epoxy resin having a structure represented by the formula (14) as a main component (softening point: 81 ° C., epoxy equivalent: 269 g / eq., Binucleate content: 6% by weight)
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[0051]
Phenol resin 5: a phenol resin represented by the formula (15) (softening point: 86 ° C., hydroxyl equivalent: 233 g / eq., Binuclear substance content: 8% by weight)
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[0052]
Brominated bisphenol A type epoxy resin (softening point 62 ° C, epoxy equivalent 365 g / eq., Bromine atom content 48% by weight)
Diantimony trioxide curing accelerator 2: a curing accelerator represented by the formula (16):

[0053]
Curing accelerator 3: Curing accelerator represented by formula (17)

[0054]
Curing accelerator 4: 1,8-diazabicyclo (5,4,0) undecene-7
[0055]
[Table 1]

[0056]
【The invention's effect】
According to the present invention, an epoxy resin composition for semiconductor encapsulation having excellent moldability can be obtained without using a halogen-based flame retardant and an antimony compound, and a semiconductor device using the same has flame retardancy and high-temperature storage characteristics. Excellent in moisture resistance reliability and solder reflow resistance.

Claims (4)

(A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator which is an adduct of a phosphine compound represented by the general formula (1) and a quinone compound represented by the general formula (2), and (D) an inorganic compound. A filler is an essential component, and (A) an epoxy resin and / or (B) a phenol resin have a structure represented by the general formulas (3) to (5), and a binuclear content of the resin is 10 to 10. An epoxy resin composition for semiconductor encapsulation containing at least one resin of 75% by weight.

(In the formula, R1 to R3 represent a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, all of which may be the same or different.)

(In the formula, R4 to R6 each represent a hydrogen atom or a hydrocarbon having 1 to 12 carbon atoms, all of which may be the same or different, and R4 and R5 may combine to form a cyclic structure.)

(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 4, b is an integer of 0 to 4. n is an average value. A positive number of 1 to 10. X is hydrogen or a glycidyl group.)

(In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other. A is an integer of 0 to 4. n is an average number and a positive number of 1 to 10. X Is hydrogen or a glycidyl group.)

(Wherein, R represents an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. B is 1 or 2. n is an average number and is a positive number of 0 or 1 to 10. X is hydrogen. Or a glycidyl group.) 2. The semiconductor encapsulation according to claim 1, wherein the curing accelerator (C), which is an adduct of the phosphine compound represented by the general formula (1) and the quinone compound represented by the general formula (2), is represented by the following formula (6). Epoxy resin composition.

The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, wherein the total amount of bromine atoms and antimony atoms contained in the entire epoxy resin composition is less than 0.1% by weight. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim 1.