JP2004143348A - Epoxy-based resin composition and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an epoxy-based resin composition excellent in resistance to breaking of wire and fluidity at higher reflow temperatures and to provide a semiconductor device sealed with the epoxy-based resin composition. <P>SOLUTION: The epoxy-based resin composition comprises (A) an epoxy resin, (B) a curing agent, (C) a filler, (D) an amino group-containing silane coupling agent and (E) a mercapto group-containing silane coupling agent as essential components, and the epoxy-based resin (A) contains a bisphenol F type epoxy resin (a) and the content of a bromine compound is ≤0.3 wt.% based on the total composition and the content of an antimony compound is ≤0.3 wt.% based on the total composition, and the filler (C) is compounded in an amount of 88-95% based on the total epoxy-based resin composition. <P>COPYRIGHT: (C)2004,JPO

Description

【００１２】
（式中、Ｒ^１〜Ｒ^４は水素原子、炭素数１〜４の低級アルキル基、フェニル基またはハロゲン原子のいずれかを示し、各々が同一であっても異なっていてもよく、Ｒ^１〜Ｒ^４の少なくとも１つの基は炭素数１〜４の低級アルキル基である。）
【００１３】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明のエポキシ系樹脂組成物は必須成分として、エポキシ樹脂（Ａ）、硬化剤（Ｂ）充填材（Ｃ）、アミノ基含有シランカップリング剤（Ｄ）、メルカプト基含有シランカップリング剤（Ｅ）を含有する。
【００１４】
本発明のエポキシ系樹脂組成物においては　、エポキシ樹脂（Ａ）がビスフェノールＦ型エポキシ樹脂（ａ）を必須成分として含有することを特徴の１つとする。
【００１５】
エポキシ樹脂としてビスフェノールＦ型エポキシ樹脂（ａ）を含有させることにより粘度を下げ成形性を向上する効果が得られる。ビスフェノールＦ型エポキシ樹脂（ａ）としては、テトラメチルビスフェノールＦ型エポキシ樹脂が好ましく使用される。
【００１６】
用途によってはエポキシ樹脂としてビスフェノールＦ型エポキシ樹脂（ａ）以外のエポキシ樹脂を併用しても良い。
【００１７】
その他のエポキシ樹脂としては１分子中に２個以上のエポキシ基を有する化合物であれば特に限定されず、モノマー、オリゴマー、ポリマー全般である。例えばアルキル置換基を持たないビスフェノールＦ型エポキシ樹脂、クレゾールノボラック型エポキシ樹脂、フェノールノボラック型エポキシ樹脂、４，４´−ビス（２，３−エポキシプロポキシ）ビフェニル、　４，４´−ビス（２，３−エポキシプロポキシ）−３，３´，５，５´−テトラメチルビフェニル、４，４´−ビス（２，３−エポキシプロポキシ）−３，３´，５，５´−テトラエチルビフェニル、４，４´−ビス（２，３−エポキシプロポキシ）−３，３´，５，５´−テトラブチルビフェニルなどのビフェニル型エポキシ樹脂、フェノールアラルキル型エポキシ樹脂、ビフェニルアラルキル型エポキシ樹脂、ナフタレン型エポキシ樹脂、ビスフェノールＡ型エポキシ樹脂、トリフェノール型エポキシ樹脂、ジシクロペンタジエン骨格含有エポキシ樹脂、トリフェニルメタン型エポキシ樹脂、およびハロゲン化エポキシ樹脂などが挙げられる。その他のエポキシ樹脂として２種以上用いても良い。
【００１８】
２種以上のエポキシ樹脂を併用する場合、ビスフェノールＦ型エポキシ樹脂（ａ）の他のエポキシ樹脂として特に好ましいものとしては例えば４，４´−ビス（２，３−エポキシプロポキシ）−３，３´，５，５´−テトラメチルビフェニル、アルキル置換基を持たないビスフェノールＦ型エポキシ樹脂等が挙げられる。
【００１９】
ビスフェノールＦ型エポキシ樹脂（ａ）の含有量はエポキシ樹脂（Ａ）全量に対して１０重量％以上が好ましい。１０％以下であると流動性が低下する。また、より流動性を向上させるため２０重量％以上がより好ましい。勿論全量であっても構わない。
【００２０】
エポキシ樹脂（Ａ）の配合量はエポキシ系樹脂組成物全体に対して通常０．５〜１２重量％、特に１〜７重量％が好ましい。
【００２１】
本発明における硬化剤（Ｂ）は、エポキシ樹脂と反応して硬化させるものであれば特に限定されず、それらの具体例としては、例えばフェノールノボラック、クレゾールノボラック、ナフトールノボラックなどのノボラック樹脂、フェノールアラルキル樹脂、ビフェニル骨格含有フェノールアラルキル樹脂、ジシクロペンタジエン骨格含有フェノール樹脂、ナフトールアラルキル樹脂、ビスフェノールＡなどのビスフェノール化合物、無水マレイン酸、無水フタル酸、無水ピロメリット酸などの酸無水物およびメタフェニレンジアミン、ジアミノジフェニルメタン、ジアミノジフェニルスルホンなどの芳香族アミンなどがあげられこれらを単独で用いても、２種以上の硬化剤を併用しても良い。硬化剤（Ｂ）の溶融粘度はＩＣＩ（１５０℃）粘度で０．４Ｐａ・ｓ以下、さらには０．２Ｐａ・ｓ以下のものが特に好ましく使用される。
【００２２】
硬化剤（Ｂ）の配合量はエポキシ系樹脂組成物全体に対して通常０．５〜１２重量％、特に１〜７重量％が好ましい。さらにはエポキシ樹脂（Ａ）と硬化剤（Ｂ）の配合比は、機械的性質、及び耐湿性の点からエポキシ樹脂（Ａ）に対する硬化剤（Ｂ）の化学当量比が０．５〜１．５、特に０．６〜１．２の範囲にあることが好ましい。
【００２３】
本発明においてエポキシ樹脂（Ａ）と硬化剤（Ｂ）の硬化反応を促進するため硬化促進剤を用いても良い。硬化促進剤は硬化を促進する物なら特に限定されず、たとえば２−メチルイミダゾール、２，４−ジメチルイミダゾール、２−エチル−４−メチルイミダゾール、２−フェニルイミダゾール、２−フェニル−４−メチルイミダゾール、２−ヘプタデシルイミダゾールなどのイミダゾール化合物、トリエチルアミン、ベンジルジメチルアミン、α−メチルベンジルメチルアミン、２−（ジメチルアミノメチル）フェノール、２，４，６−トリス（ジメチルアミノメチル）フェノール、１，８−ジアザビシクロ（５，４，０）ウンデセン−７などの３級アミン化合物、ジルコニウムテトラメトキシド、ジルコニウムテトラプロポキシド、テトラキス（アセチルアセトナト）ジルコニウム、トリ（アセチルアセトナト）アルミニウムなどの有機金属化合物およびトリフェニルホスフィン、トリメチルホスフィン、トリエチルホスフィン、トリブチルホスフィン、トリ（ｐ−メチルフェニル）ホスフィン、トリ（ノニルフェニル）ホスフィンなどの有機ホスフィン化合物があげられる。なかでも信頼性および成形性の点から有機ホスフィン化合物が好ましく、トリフェニルホスフィンが特に好ましく用いられる。また、これらの硬化促進剤は用途によっては２種以上を併用してもよい。硬化促進剤の添加量はエポキシ樹脂（Ａ）１００重量部に対して０．１〜１０重量部の範囲が好ましい。
【００２４】
本発明における充填材（Ｃ）としては、無機充填材が好ましく、具体的には非晶性シリカ、結晶性シリカ、炭酸カルシウム、炭酸マグネシウム、アルミナ、マグネシア、クレー、タルク、ケイ酸カルシウム、酸化チタンや酸化アンチモンなどの金属酸化物、アスベスト、ガラス繊維およびガラス球などが挙げられるが、中でも非晶性シリカは線膨脹係数を低下させる効果が大きく、低応力化に有効なため好ましく用いられる。形状としては、破砕状のものや球状のものが用いられ、流動性の点から球状のものが好ましく使用される。非晶性シリカのなかでも石英を溶融して製造される球状溶融シリカが特に好ましく使用される。
【００２５】
ここでいう非晶性シリカは、一般的には真比重が２．３以下のものを意味する。この非晶性シリカの製造においては石英を溶融して製造される（溶融シリカ）のが一般的であるが必ずしも溶融状態を経る必要はなく、公知の任意の製造方法を用いることができ、例えば結晶性シリカを溶融する方法および金属ケイ素の酸化による方法、アルコキシシランの加水分解など、各種原料からの合成方法が使用できる。
【００２６】
本発明において、充填材（Ｃ）の割合は、全樹脂組成物に対して８８重量％〜９５重量％であることを特徴とする。充填材（Ｃ）の含有量が８８重量％以上であると封止樹脂の低熱線膨張化、低吸湿化が達成でき、厳しい要求レベルにおける十分な耐リフロー信頼性、特に耐ワイア断線特性が得られる。また、充填材（Ｃ）の含有量を多くすることにより、難燃性の効果をあわせて得ることができる。
【００２７】
充填材の粒径および粒度分布については、特に限定はないが、流動性、成形時のバリ低減の点から、平均粒径（メディアン径を意味する。以下同じ。）が５〜３０μｍの範囲にあることが特に好ましい。また、平均粒径または粒度分布の異なる充填材を２種以上組み合わせることもできる。
【００２８】
また得られる半導体装置のソフトエラーの問題を回避するために、エポキシ系樹脂組成物中のウラン、トリウムなどα線放出物質の濃度を、極めて少なく、具体的にはそれぞれ１０ｐｐｂ以下とすることが好ましい。
【００２９】
本発明では、アミノ基含有シランカップリング剤（Ｄ）、メルカプト基含有シランカップリング剤（Ｅ）を必須成分として含有することを特徴の一つとする。これらのシランカップリング剤で充填材を、他の構成成分と、同時にブレンドしても、ブレンドする以前にあらかじめ処理しておいてもよい。アミノ基含有シランカップリング剤としては、アミノ基および有機基がケイ素原子に直結したもの、およびその部分加水分解縮合物が一般的に用いられる。アミノ基含有シランカップリング剤の例としては、γ−（Ｎ−フェニルアミノ）プロピルトリメトキシシラン、γ−（Ｎ−フェニルアミノ）プロピルメチルジメトキシシラン、γ−（Ｎ−メチルアミノ）プロピルトリメトキシシラン、γ−（Ｎ−メチルアミノプロピル）メチルジメトキシシラン、γ−（Ｎ−エチルアミノ）プロピルトリメトキシシラン、γ−（Ｎ−エチルアミノ）プロピルメチルジメトキシシラン、γ−（Ｎ−エチルアミノ）プロピルメチルトリメトキシシラン、Ｎ−β−（アミノエチル）−γ−アミノプロピルトリメトキシシラン、Ｎ−β−（アミノエチル）−γ−アミノプロピルメチルジメトキシシラン、Ｎ−β−（アミノエチル）−γ−アミノプロピルトリエチルシラン、γ−アミノプロピルトリエトキシシラン、γ−アミノプロピルメチルジエトキシシラン、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルメチルジメトキシシラン、γ−（Ｎ，Ｎ−ジメチルアミノ）プロピルトリメトキシシラン等が挙げられる。また、メルカプト基含有シランカップリング剤としては、メルカプト基および有機基がケイ素原子に直結したもの、およびその部分加水分解縮合物が一般的に用いられる。メルカプト基含有シランカップリング剤の例としては、γ−メルカプトプロピルトリメトキシシラン、γ−メルカプトプロピルメチルジメトキシシラン等が挙げられる。シランカップリング剤中の有機基としては、窒素原子、酸素原子、ハロゲン原子、硫黄原子などによって置換された炭化水素基のものが使用される。
また、用途によってはアミノ基含有シランカップリング剤とメルカプト基含有シランカップリング剤以外のシランカップリング剤を、本発明の効果を損なわない範囲内で併用しても良い。併用できるシランカップリング剤の具体的な例としては、γ−グリシドキシプロピルトリメトキシシラン、γ−グリシドキシプロピルメチルジメトキシシシラン、γ−（２，３−エポキシシクロヘキシル）プロピルトリメトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、γ−メタクリロキシプロピルメチルジメトキシシランなどが挙げられる。
【００３０】
カップリング剤の配合割合としてはエポキシ系樹脂組成物全量に対して０．１〜２重量％添加することが流動性及び充填性の点で好ましい。
【００３１】
本発明のエポキシ系樹脂組成物では、耐ワイア断線を向上させるために、ブロム化合物およびアンチモン化合物の含有量を０にするか、存在したとしてもブロム化合物の含有量を組成物全体の０．３重量％以下とし、かつアンチモン化合物の含有量を組成物全体の０．３重量％以下とすることが必要である。ここで存在が許されるアンチモン化合物としては、例えば三酸化アンチモン、四酸化アンチモン、五酸化アンチモンがあげられる。また、ブロム化合物としては、例えば、、ブロム化ビスフェノールＡ型エポキシ樹脂、ブロム化フェノールノボラック型エポキシ樹脂などのブロム化エポキシ樹脂、ブロム化ポリカーボネート樹脂、ブロム化ポリスチレン樹脂、ブロム化ポリフェニレンオキサイド樹脂、テトラブロモビスフェノールＡ、デカブロモジフェニルエーテルなどがあげられ、なかでも、ブロム化ビスフェノールＡ型エポキシ樹脂、ブロム化フェノールノボラック型エポキシ樹脂などのブロム化エポキシ樹脂の共存の許容が、成形性の点から特に好ましい。
【００３２】
本発明のエポキシ樹脂組成物中に存在するブロム化合物の量は、エポキシ樹脂組成物全体の０．３重量％以下であることが、難燃性および密着性の点からも必要であるが、好ましくは０．１重量％以下である。ブロム原子に換算すると、ブロム原子が全体の０．２重量％以下であることが好ましく、特に好ましくは０．０７重量％以下である。
【００３３】
本発明のエポキシ樹脂組成物中に存在するアンチモン化合物の量は、エポキシ樹脂組成物全体の０．３重量％以下であることが、難燃性および高温信頼性の点からも必要であるが、好ましくは０．１重量％以下である。
【００３４】
また、これら難燃剤、難燃助剤の共存を許容する場合、エポキシ系樹脂組成物から発生する不要物の廃棄の容易さ、および半導体装置の長期信頼性の観点からもハロゲン原子およびアンチモン原子それぞれが、エポキシ系樹脂組成物に対して０．３重量％以下であることが必須であり、特に好ましくは０．１％以下である。
【００３５】
本発明のエポキシ系樹脂組成物は、さらに次に挙げる各種添加剤を任意に含有することができる。カーボンブラックおよび酸化鉄などの各種着色剤や各種顔料、シリコーンゴム、オレフィン系共重合体、変性ニトリルゴム、変性ポリブタジエンゴムなどの各種エラストマー、シリコーンオイルなどの各種熱可塑性樹脂、フッ素系、シリコーン系などの界面活性剤、カルナウバワックスなどの天然植物性ワックス、長鎖脂肪酸、長鎖脂肪酸の金属塩、モンタン酸エステルなどの長鎖脂肪酸のエステル、長鎖脂肪酸のアミドおよびポリエチレンワックスなどのパラフィンワックス、その他各種離型剤、およびハイドロタルサイト類などのイオン捕捉剤、有機過酸化物などの架橋剤。
【００３６】
本発明のエポキシ系樹脂組成物は上記各成分を溶融混練によって製造することが好ましい。たとえば各種原料をミキサーなどの公知の方法で混合した後、バンバリーミキサー、ニーダー、ロール、単軸もしくは二軸の押出機およびコニーダーなどの公知の混練方法を用いて溶融混練することにより製造される。溶融混練時の樹脂温度としては、通常７０〜１５０℃の範囲が使用される。
【００３７】
本発明のエポキシ系樹脂組成物は、加熱混練で溶融し、冷却後さらに粉砕した粉末の形状、粉末を打錠して得られるタブレットの形状、加熱混練で溶融し型内で冷却固化したタブレットの形状、加熱混練で溶融し押し出ししてさらに切断したペレットの形状などの状態で使用できる。
【００３８】
そしてこれらの形状から半導体素子の封止に供され半導体装置の製造が行われる。半導体を基板に固定した部材に対して、本発明のエポキシ系樹脂組成物を、例えば１２０〜２５０℃、好ましくは１５０〜２００℃の温度で、トランスファ成形、インジェクション成形、注型法などの方法で成形して、エポキシ系樹脂組成物の硬化物によって封止された半導体装置が製造される。また必要に応じて追加熱処理（例えば、１５０〜２００℃、２〜１６時間）を行うことができる。
【００３９】
本発明における２６０℃リフローとは一般的なリフロー装置において最高温度を２６０℃に設定し、加熱処理することを言う。
【００４０】
【実施例】
以下、実施例により本発明を具体的に説明するが、本発明はここに掲げた実施例によって限定されるものではない。なお、実施例中の％は重量％を示す。
【００４１】
［実施例１〜８、比較例１〜５］
表１に示した各成分を表２〜３に示す組成比（重量比）で、ミキサーによりドライブレンドした後、ロール表面温度９０℃のミキシングロールを用いて５分間加熱混練後、冷却、粉砕して半導体封止用のエポキシ系樹脂組成物を得た。
【００４２】
【表１】

【００４３】
＜ワイア断線特性（耐リフロー信頼性）評価＞
得られた各樹脂組成物を用いて２０８ｐｉｎＱＦＰ（外形：２８ｍｍ×２８ｍｍ×３．７ｍｍ、フレーム材料：４２アロイ）用金型を用いて、低圧トランスファー成形機で金型温度１７５℃、キュアータイム６０秒間の条件でパッケージを成形した。なお評価用のチップとしては表面に窒化珪素膜を被覆したチップサイズ８ｍｍ×８ｍｍ×０．３ｍｍの模擬素子を搭載した。
【００４４】
次に下記の測定法により各樹脂組成物の物性を評価した。結果を表２および表３に示す。
＜ワイア断線特性（耐リフロー信頼性）＞
上記成形にて得られた２０８ｐｉｎＱＦＰを８５℃／６０％ＲＨで１６８時間加湿後、最高温度２６０℃のＩＲリフロー炉で加熱処理した。なお、リフロー炉の温度プロファイルは、１５０℃〜２００℃の領域を６０秒〜１００秒、２００℃から２６０℃の昇温速度を１．５〜２．５℃／秒、最高温度である２５５℃〜２６５℃の領域で１０〜２０秒維持し、２６０℃から２００℃の降温速度を１．５〜２．５℃／秒とした。リフロー後のパッケージを開封し、リード部分と接合（セカンドボンディング部分）している金ワイアのクラックをＳＥＭにて観察し、クラックが、ボンディングボールに全く発生していない時を◎、全幅の１／２以下の時を○、１／２以上全幅未満の時△、全幅の時×として評価した。
【００４５】
＜密着性評価（耐リフロー信頼性）＞
上記リフロー後パッケージ内部の銀メッキ部分を超音波探傷機により観察し、剥離が生じている面積を計算し剥離率（％）とした。
【００４６】
＜パッケージ充填性（成形性）評価＞
上記成形により得られた２０８ｐｉｎＱＦＰパッケージ１０個を成形後に目視および断面切断後、２０倍の顕微鏡を用いて観察し、未充填の有無を調べた。未充填が発生した不良パッケージを除く、良好に得られたパッケージ数を求めた。
【００４７】
＜長期信頼性評価＞
１６ｐｉｎＤＩＰ（デュアルインラインパッケージ）を成形し、１４０℃／８５％ＲＨ、ＤＣ２０Ｖ印加下でＰＣＢＴを評価し、累積故障率６３％になる時間を求めＰＣＢＴ特性寿命とした。
【００４８】
【表２】

【００４９】
【表３】

【００５０】
表２、３に評価結果を示す。表に見られるように、アミノ基およびメルカプト基含有シランカップリング剤を用いていない場合や、充填材の割合が８８％未満である場合、耐リフロー信頼性が不十分である（比較例１〜３、６）。また、テトラメチルビスフェノールＦ型エポキシ樹脂を用いていない場合は成形性が不十分である（比較例４〜６）。また、難燃剤である臭素化ビスフェノールＡ型エポキシ樹脂の添加量が、０．３％以上であるとＰＣＢＴ特性寿命が大きく低下する（比較例７）。それに対し、本発明のエポキシ系樹脂組成物はリフロー時のワイア断線特性、成形性およびＰＣＢＴ特性寿命のいずれも優れている。
【００５１】
【発明の効果】
以上説明したように、本発明によればより高温のリフロー温度において、耐ワイア断線、流動性に優れるエポキシ系樹脂組成物、及び該エポキシ系樹脂組成物で封止してなる半導体装置を得ることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an epoxy resin composition which is excellent in wire breakage and moldability at high temperature reflow and is particularly suitable for semiconductor encapsulation.
[0002]
[Prior art]
As a method of sealing electronic circuit components such as semiconductor devices, resin sealing with phenolic resin, silicone resin, epoxy resin, etc. has been proposed in addition to hermetic sealing with metal or ceramics. The resin used is called a sealing resin. Among them, resin encapsulation with epoxy resin is most actively performed from the viewpoint of balance between economy, productivity and physical properties. The sealing method using an epoxy resin is generally performed by using a composition in which a curing agent, a filler, and the like are added to an epoxy resin, setting the semiconductor element in a mold, and sealing by a transfer molding method or the like. Has been done.
[0003]
In recent years, the density and automation of mounting semiconductor device packages on printed circuit boards have been increasing, and instead of the conventional “insertion mounting method” in which lead pins are inserted into holes in the board, the semiconductor device package is soldered to the board surface. “Surface mounting method” has become popular.
[0004]
In the surface mounting method, mounting is usually performed by solder reflow. In this method, a semiconductor device package is placed on a substrate, and the semiconductor device package is exposed to a high temperature of 200 ° C. or more, and the solder previously applied to the substrate is melted to adhere the semiconductor device package to the substrate surface. In such a mounting method, since the entire semiconductor device package is exposed to high temperatures, stress is applied to the leads in the semiconductor device and the gold wires connecting the leads to the semiconductor element, and cracks occur in the bonding portions between the leads and the gold wires, and the semiconductor device package is cracked. It adversely affects the electrical characteristics of the device. In addition, separation may occur at the interface between the chip or the lead frame and the sealing material, which may reduce the reliability of the semiconductor device. Furthermore, in recent years, lead-free solders that do not contain lead are being used from the viewpoint of environmental protection. However, lead-free solders have a high melting point, which increases the reflow temperature, and thus has a higher reflow reliability than before. It has been demanded.
[0005]
In general, it has been known that increasing the proportion of the filler in the sealing resin composition is effective for improving the reflow resistance. This is because the hygroscopicity is reduced by reducing the resin component in the sealing resin composition. However, if the ratio of the filler in the sealing resin composition is simply increased, the fluidity deteriorates, and problems such as unfilled package, stage shift, and wire flow occur.
[0006]
Therefore, in order to improve the adhesion, which is one of the reflow resistance reliability, addition of mercaptosilane (for example, Patent Document 1), and use of bifunctional epoxy, low-viscosity phenol, or mercaptosilaneaminosilane-treated silica (for example, Patent Reference 2) has been proposed. Further, as a method of improving the moldability, a compound of a tetramethylbisphenol F type epoxy resin as an epoxy resin (for example, Patent Document 3) and an epoxy resin composition further containing a phenol aralkyl resin as a curing agent (for example, Patent Document 3) are known. Proposed.
[0007]
[Patent Document 1]
JP 2001-11289 A (Claim 1)
[Patent Document 2]
JP-A-9-165499 (Claim 1)
[Patent Document 3]
Japanese Patent No. 3192953 (Claim 1)
[Patent Document 4]
JP-A-6-345850 (Claim 1)
[Patent Document 5]
JP-A-8-134183 (Claim 1)
[0008]
[Problems to be solved by the invention]
Although the methods of Patent Documents 1 and 2 provide an effect of improving adhesion, the wire disconnection resistance and moldability are not sufficient. In addition, the methods disclosed in Patent Documents 3 and 4 have an effect of improving the moldability, but are still insufficient.
[0009]
The object of the present invention has been made in view of the above circumstances, and at higher reflow temperatures, an epoxy resin composition having excellent wire disconnection resistance and excellent fluidity, and sealing with the epoxy resin composition. It is an object of the present invention to provide a stopped semiconductor device.
[0010]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, have reached the present invention.
That is, the present invention contains the epoxy resin (A), the curing agent (B), the filler (C), the amino group-containing silane coupling agent (D), and the mercapto group-containing silane coupling agent (E) as essential components. An epoxy resin composition, wherein the epoxy resin (A) is a bisphenol F type epoxy resin (a) represented by the following general formula (I) (hereinafter, simply referred to as a bisphenol F type epoxy resin (a)). And the content of the bromo compound is 0.3% by weight or less of the whole composition, and the content of the antimony compound is 0.3% by weight or less of the whole composition. An epoxy resin composition characterized in that the epoxy resin composition is blended in an amount of 88 to 95% in the epoxy resin composition.
[0011]
Embedded image

[0012]
(Wherein, R ¹ to R ⁴ is a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, indicates one of a phenyl group, or a halogen atom, may be each optionally substituted by one or more identical, R ¹ ~ At least one group of R ⁴ is a lower alkyl group having 1 to 4 carbon atoms.)
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The epoxy resin composition of the present invention comprises, as essential components, an epoxy resin (A), a curing agent (B), a filler (C), an amino group-containing silane coupling agent (D), and a mercapto group-containing silane coupling agent (E). ).
[0014]
The epoxy resin composition of the present invention is characterized in that the epoxy resin (A) contains a bisphenol F type epoxy resin (a) as an essential component.
[0015]
By including the bisphenol F type epoxy resin (a) as the epoxy resin, the effect of lowering the viscosity and improving the moldability can be obtained. As the bisphenol F type epoxy resin (a), a tetramethyl bisphenol F type epoxy resin is preferably used.
[0016]
Depending on the application, an epoxy resin other than the bisphenol F type epoxy resin (a) may be used as the epoxy resin.
[0017]
Other epoxy resins are not particularly limited as long as they are compounds having two or more epoxy groups in one molecule, and include all monomers, oligomers, and polymers. For example, bisphenol F type epoxy resin having no alkyl substituent, cresol novolak type epoxy resin, phenol novolak type epoxy resin, 4,4′-bis (2,3-epoxypropoxy) biphenyl, 4,4′-bis (2, 3-epoxypropoxy) -3,3 ', 5,5'-tetramethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetraethylbiphenyl, 4, Biphenyl type epoxy resin such as 4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetrabutylbiphenyl, phenol aralkyl type epoxy resin, biphenyl aralkyl type epoxy resin, naphthalene type epoxy resin, Bisphenol A type epoxy resin, triphenol type epoxy resin, dicyclopentadiene bone Containing epoxy resin, triphenylmethane type epoxy resins, and halogenated epoxy resins. Two or more epoxy resins may be used.
[0018]
When two or more epoxy resins are used in combination, particularly preferred as other epoxy resins of the bisphenol F type epoxy resin (a) are, for example, 4,4′-bis (2,3-epoxypropoxy) -3,3 ′. , 5,5'-tetramethylbiphenyl, bisphenol F type epoxy resin having no alkyl substituent, and the like.
[0019]
The content of the bisphenol F type epoxy resin (a) is preferably at least 10% by weight based on the total amount of the epoxy resin (A). If it is less than 10%, the fluidity will decrease. In order to further improve the fluidity, the content is more preferably 20% by weight or more. Of course, the entire amount may be used.
[0020]
The amount of the epoxy resin (A) is usually 0.5 to 12% by weight, preferably 1 to 7% by weight, based on the entire epoxy resin composition.
[0021]
The curing agent (B) in the present invention is not particularly limited as long as it cures by reacting with an epoxy resin. Specific examples thereof include novolak resins such as phenol novolak, cresol novolak, and naphthol novolak, and phenol aralkyl. Resins, biphenyl skeleton-containing phenol aralkyl resins, dicyclopentadiene skeleton-containing phenol resins, naphthol aralkyl resins, bisphenol compounds such as bisphenol A, maleic anhydride, phthalic anhydride, acid anhydrides such as pyromellitic anhydride and metaphenylenediamine, Examples thereof include aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone. These may be used alone, or two or more curing agents may be used in combination. The curing agent (B) having an ICI (150 ° C.) viscosity of 0.4 Pa · s or less, particularly 0.2 Pa · s or less, is particularly preferably used.
[0022]
The compounding amount of the curing agent (B) is usually 0.5 to 12% by weight, preferably 1 to 7% by weight, based on the whole epoxy resin composition. Furthermore, the mixing ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of the curing agent (B) to the epoxy resin (A) is 0.5 to 1. 5, preferably in the range of 0.6 to 1.2.
[0023]
In the present invention, a curing accelerator may be used to accelerate the curing reaction between the epoxy resin (A) and the curing agent (B). The curing accelerator is not particularly limited as long as it promotes curing. For example, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole , Imidazole compounds such as 2-heptadecyl imidazole, triethylamine, benzyldimethylamine, α-methylbenzylmethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8 -Tertiary amine compounds such as diazabicyclo (5,4,0) undecene-7; organic metals such as zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, and tri (acetylacetonato) aluminum Compound and triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tri (p- methylphenyl) phosphine, an organic phosphine compound such as tri (nonylphenyl) phosphine and the like. Among them, an organic phosphine compound is preferable from the viewpoint of reliability and moldability, and triphenylphosphine is particularly preferably used. These curing accelerators may be used in combination of two or more depending on the use. The addition amount of the curing accelerator is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the epoxy resin (A).
[0024]
As the filler (C) in the present invention, an inorganic filler is preferable. Specifically, amorphous silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide And metal oxides such as antimony oxide, asbestos, glass fibers and glass spheres. Among them, amorphous silica is preferably used because it has a large effect of lowering the linear expansion coefficient and is effective in reducing stress. As the shape, a crushed shape or a spherical shape is used, and a spherical shape is preferably used from the viewpoint of fluidity. Among the amorphous silicas, spherical fused silica produced by melting quartz is particularly preferably used.
[0025]
The amorphous silica referred to herein generally means one having a true specific gravity of 2.3 or less. In the production of this amorphous silica, it is common to produce it by fusing quartz (fused silica), but it is not always necessary to go through a molten state, and any known production method can be used. Synthesis methods from various raw materials, such as a method of melting crystalline silica, a method of oxidizing metal silicon, and a hydrolysis of alkoxysilane, can be used.
[0026]
In the present invention, the proportion of the filler (C) is characterized in that it is from 88% by weight to 95% by weight based on the whole resin composition. When the content of the filler (C) is 88% by weight or more, low thermal expansion and low moisture absorption of the sealing resin can be achieved, and sufficient reflow reliability at a strict required level, particularly, wire disconnection resistance can be obtained. Can be Further, by increasing the content of the filler (C), the effect of flame retardancy can be obtained together.
[0027]
The particle size and particle size distribution of the filler are not particularly limited, but from the viewpoint of fluidity and reduction of burrs at the time of molding, the average particle size (mean diameter, hereinafter the same) is in the range of 5 to 30 μm. It is particularly preferred that there is. Further, two or more kinds of fillers having different average particle sizes or different particle size distributions can be combined.
[0028]
In order to avoid the problem of soft errors in the obtained semiconductor device, the concentration of α-ray emitting substances such as uranium and thorium in the epoxy-based resin composition is extremely low, and specifically, is preferably set to 10 ppb or less, respectively. .
[0029]
One of the features of the present invention is that it contains an amino group-containing silane coupling agent (D) and a mercapto group-containing silane coupling agent (E) as essential components. The filler may be simultaneously blended with these constituents with these silane coupling agents, or may be pre-treated before blending. As the amino group-containing silane coupling agent, those in which an amino group and an organic group are directly bonded to a silicon atom, and a partially hydrolyzed condensate thereof are generally used. Examples of amino group-containing silane coupling agents include γ- (N-phenylamino) propyltrimethoxysilane, γ- (N-phenylamino) propylmethyldimethoxysilane, γ- (N-methylamino) propyltrimethoxysilane Γ- (N-methylaminopropyl) methyldimethoxysilane, γ- (N-ethylamino) propyltrimethoxysilane, γ- (N-ethylamino) propylmethyldimethoxysilane, γ- (N-ethylamino) propylmethyl Trimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl) -γ-amino Propyltriethylsilane, γ-aminopropyltriethoxysilane, γ-aminopropyl Pills methyl diethoxy silane, .gamma.-aminopropyltrimethoxysilane, .gamma.-aminopropyl methyl dimethoxy silane, γ- (N, N- dimethylamino) propyl trimethoxysilane, and the like. Further, as the silane coupling agent containing a mercapto group, those in which a mercapto group and an organic group are directly bonded to a silicon atom, and a partially hydrolyzed condensate thereof are generally used. Examples of mercapto group-containing silane coupling agents include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, and the like. As the organic group in the silane coupling agent, a hydrocarbon group substituted by a nitrogen atom, an oxygen atom, a halogen atom, a sulfur atom, or the like is used.
Further, depending on the use, a silane coupling agent other than the amino group-containing silane coupling agent and the mercapto group-containing silane coupling agent may be used in combination as long as the effects of the present invention are not impaired. Specific examples of the silane coupling agent that can be used in combination include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ- (2,3-epoxycyclohexyl) propyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and the like.
[0030]
The mixing ratio of the coupling agent is preferably 0.1 to 2% by weight based on the total amount of the epoxy resin composition in terms of fluidity and filling.
[0031]
In the epoxy resin composition of the present invention, in order to improve wire breakage resistance, the content of the bromo compound and the antimony compound is reduced to 0, or even if present, the content of the bromo compound is set to 0.3% of the entire composition. % By weight and the content of the antimony compound must be 0.3% by weight or less based on the whole composition. Examples of antimony compounds that can be present here include antimony trioxide, antimony tetroxide, and antimony pentoxide. Examples of the brominated compound include, for example, brominated epoxy resins such as brominated bisphenol A type epoxy resin and brominated phenol novolak type epoxy resin, brominated polycarbonate resin, brominated polystyrene resin, brominated polyphenylene oxide resin, tetrabromo Examples thereof include bisphenol A and decabromodiphenyl ether, and among them, the coexistence of a brominated epoxy resin such as a brominated bisphenol A type epoxy resin and a brominated phenol novolak type epoxy resin is particularly preferable from the viewpoint of moldability.
[0032]
The amount of the bromo compound present in the epoxy resin composition of the present invention is preferably 0.3% by weight or less based on the entire epoxy resin composition from the viewpoint of flame retardancy and adhesion, but is preferably used. Is 0.1% by weight or less. In terms of bromo atoms, the bromo atoms are preferably at most 0.2% by weight, more preferably at most 0.07% by weight.
[0033]
It is necessary that the amount of the antimony compound present in the epoxy resin composition of the present invention is 0.3% by weight or less based on the entire epoxy resin composition in view of flame retardancy and high-temperature reliability. Preferably it is 0.1% by weight or less.
[0034]
Further, when the coexistence of these flame retardants and flame retardant assistants is allowed, the halogen atom and the antimony atom are also considered from the viewpoint of the easiness of disposal of unnecessary substances generated from the epoxy resin composition and the long-term reliability of the semiconductor device. However, it is essential that the content is 0.3% by weight or less, particularly preferably 0.1% or less, based on the epoxy resin composition.
[0035]
The epoxy-based resin composition of the present invention can further optionally contain the following various additives. Various colorants and pigments such as carbon black and iron oxide, various elastomers such as silicone rubber, olefin copolymer, modified nitrile rubber, modified polybutadiene rubber, various thermoplastic resins such as silicone oil, fluorine-based, silicone-based, etc. Surfactants, natural vegetable waxes such as carnauba wax, long chain fatty acids, metal salts of long chain fatty acids, esters of long chain fatty acids such as montanic acid esters, amides of long chain fatty acids and paraffin waxes such as polyethylene waxes, Other release agents, ion scavengers such as hydrotalcites, and crosslinking agents such as organic peroxides.
[0036]
The epoxy resin composition of the present invention is preferably produced by melt-kneading the above components. For example, it is manufactured by mixing various raw materials by a known method such as a mixer, and then melt-kneading using a known kneading method such as a Banbury mixer, a kneader, a roll, a single-screw or twin-screw extruder and a co-kneader. As the resin temperature during melt-kneading, a range of usually 70 to 150 ° C. is used.
[0037]
The epoxy resin composition of the present invention is melted by heating and kneading, the shape of the powder further pulverized after cooling, the shape of the tablet obtained by tableting the powder, the tablet which is melted by heating and kneading and solidified by cooling in a mold. It can be used in the form of pellets, which are melted by heat kneading, extruded and further cut.
[0038]
Then, the semiconductor element is sealed from these shapes to manufacture a semiconductor device. For a member having a semiconductor fixed to a substrate, the epoxy resin composition of the present invention is subjected to, for example, transfer molding, injection molding, or a casting method at a temperature of 120 to 250 ° C, preferably 150 to 200 ° C. A semiconductor device molded and sealed with a cured product of the epoxy resin composition is manufactured. If necessary, an additional heat treatment (for example, 150 to 200 ° C., 2 to 16 hours) can be performed.
[0039]
260 ° C. reflow in the present invention means that a maximum temperature is set to 260 ° C. in a general reflow apparatus and heat treatment is performed.
[0040]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to the examples described here. Incidentally,% in the examples indicates% by weight.
[0041]
[Examples 1 to 8, Comparative Examples 1 to 5]
Each component shown in Table 1 was dry-blended by a mixer at a composition ratio (weight ratio) shown in Tables 2 and 3, then heated and kneaded for 5 minutes using a mixing roll having a roll surface temperature of 90 ° C, and then cooled and pulverized. Thus, an epoxy resin composition for semiconductor encapsulation was obtained.
[0042]
[Table 1]

[0043]
<Evaluation of wire disconnection characteristics (reflow resistance)>
Using each of the obtained resin compositions, a mold for 208 pin QFP (outer size: 28 mm × 28 mm × 3.7 mm, frame material: 42 alloy) was used at a low pressure transfer molding machine at a mold temperature of 175 ° C. and a cure time of 60 seconds. The package was molded under the following conditions. As a chip for evaluation, a simulated element having a chip size of 8 mm × 8 mm × 0.3 mm having a surface coated with a silicon nitride film was mounted.
[0044]
Next, the physical properties of each resin composition were evaluated by the following measurement methods. The results are shown in Tables 2 and 3.
<Wire disconnection characteristics (reflow resistance)>
The 208-pin QFP obtained by the above molding was humidified at 85 ° C./60% RH for 168 hours, and then heat-treated in an IR reflow furnace at a maximum temperature of 260 ° C. The temperature profile of the reflow furnace is as follows: a region of 150 ° C. to 200 ° C. is 60 seconds to 100 seconds, a temperature rising rate from 200 ° C. to 260 ° C. is 1.5 to 2.5 ° C./second, and the maximum temperature is 255 ° C. The temperature was maintained in the region of ２６265 ° C. for 10 to 20 seconds, and the temperature reduction rate from 260 ° C. to 200 ° C. was 1.5 to 2.5 ° C./sec. The package after reflow was opened, and cracks of the gold wire bonded to the lead portion (second bonding portion) were observed with a SEM. The case of 2 or less was evaluated as ○, the case of 以上 or more and less than the full width, and the case of full width x.
[0045]
<Adhesion evaluation (reflow resistance)>
After the reflow, the silver-plated portion inside the package was observed with an ultrasonic flaw detector, and the area where peeling occurred was calculated to be the peeling rate (%).
[0046]
<Evaluation of package filling (moldability)>
Ten 208 pin QFP packages obtained by the above-mentioned molding were visually observed after the molding, cut off in section, and then observed using a 20-power microscope to check for unfilled parts. The number of well-obtained packages excluding defective packages in which unfilling occurred was determined.
[0047]
<Long-term reliability evaluation>
A 16-pin DIP (dual in-line package) was molded, the PCBT was evaluated at 140 ° C./85% RH, and DC 20 V applied, and the time at which the cumulative failure rate reached 63% was determined as the PCBT characteristic life.
[0048]
[Table 2]

[0049]
[Table 3]

[0050]
Tables 2 and 3 show the evaluation results. As can be seen from the table, when no amino group- and mercapto group-containing silane coupling agent was used, or when the proportion of the filler was less than 88%, the reflow resistance was insufficient (Comparative Examples 1 to 5). 3, 6). When no tetramethylbisphenol F-type epoxy resin is used, the moldability is insufficient (Comparative Examples 4 to 6). Further, when the amount of the brominated bisphenol A type epoxy resin as the flame retardant is 0.3% or more, the life of the PCBT characteristic is significantly reduced (Comparative Example 7). On the other hand, the epoxy resin composition of the present invention is excellent in all of wire disconnection characteristics during reflow, moldability, and PCBT characteristic life.
[0051]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain an epoxy resin composition excellent in wire disconnection resistance and fluidity at a higher reflow temperature, and a semiconductor device encapsulated with the epoxy resin composition. Can be.

Claims (2)

Epoxy resin composition containing epoxy resin (A), curing agent (B), filler (C), amino group-containing silane coupling agent (D), and mercapto group-containing silane coupling agent (E) as essential components Wherein the epoxy resin (A) contains a bisphenol F type epoxy resin (a) represented by the following general formula (I), and the content of a bromo compound is 0.3% by weight or less of the whole composition. Wherein the content of the antimony compound is 0.3% by weight or less of the whole composition, and the filler (C) is blended in an amount of 88 to 95% in the whole epoxy resin composition. Resin composition.

(Wherein, R ¹ to R ⁴ is a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, indicates one of a phenyl group, or a halogen atom, may be each optionally substituted by one or more identical, R ¹ ~ At least one group of R ⁴ is a lower alkyl group having 1 to 4 carbon atoms.) A semiconductor device sealed with a cured product of the epoxy resin composition according to claim 1.