JP4910264B2 - Epoxy resin composition and semiconductor device - Google Patents

Description

」である。
【００１２】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【００１３】
本発明は必須成分として、エポキシ樹脂（Ａ）、硬化剤（Ｂ）、充填材（Ｃ）およびシランカップリング剤（Ｄ）を含有する。
【００１４】
本発明においては 、エポキシ樹脂（Ａ）が下記一般式（Ｉ）で表されるテトラメチルビスフェノールＦ型エポキシ樹脂を必須成分として含有することを特徴とする。
【００１５】
【化５】

【００１６】
エポキシ樹脂に一般式（Ｉ）で表されるテトラメチルビスフェノールＦ型エポキシ樹脂を含有させることによりリフロー時の膨れ特性が向上し、粘度を下げ成形性を向上する効果も得られる。一般式（Ｉ）で表されるテトラメチルビスフェノールＦ型エポキシ樹脂エポキシ樹脂（ａ）の含有量はエポキシ樹脂（Ａ）全量に対して１０重量％以上が好ましく、エポキシ樹脂（Ａ）全量に対して５０重量％以上であることががさらに好ましい。
【００１７】
用途によっては一般式（Ｉ）で表されるエポキシ樹脂以外のエポキシ樹脂を併用しても良い。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、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、膨れ特性改良の観点から一般式（Ｉ）で表されるエポキシ樹脂の含有量は添加効果をより高く発揮するためエポキシ樹脂（Ａ）全量に対して１０重量％以上が好ましく、エポキシ樹脂（Ａ）全量に対して５０重量％以上であることがさらに好ましい。
【００１９】
エポキシ樹脂（Ａ）の配合量はエポキシ樹脂組成物全体に対して通常０．５〜１０重量％、特に１〜６重量％が好ましい。
【００２０】
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１Ｐａ・s以下、さらには０．３Ｐａ・ｓ以下のものが特に好ましく使用される。
【００２１】
硬化剤（Ｂ）としてはリフロー信頼性の点から下記一般式（II）で表されるフェノールアラルキル樹脂が特に好ましく使用され、さらに好ましくは下記一般式（III）で表されるp-キシレン型フェノールアラルキル樹脂が良い。
【００２２】
【化６】

【００２３】
【化７】

【００２４】
２種以上の硬化剤を併用する場合、一般式（II）で表される硬化剤の含有量は硬化剤（Ｂ）全量に対して１０重量％以上が好ましく、２０重量％以上であることがさらに好ましい。
【００２５】
２種以上の硬化剤を併用する場合、さらに好ましくは膨れ特性改良の観点から一般式（III）で表される硬化剤の含有量は硬化剤（Ｂ）全量に対して１０重量％以上が好ましく、２０重量％以上であることがより好ましい。
【００２６】
硬化剤（Ｂ）の配合量はエポキシ樹脂組成物全体に対して通常０．５〜１０重量％、特に１〜６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、及び耐湿性も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０．６〜１．３の範囲にあることが好ましい。
【００２７】
また、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触媒を用いても良い。硬化触媒は硬化反応を促進するものであれば特に限定されず、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、テトラフェニルホスフォニウム・テトラフェニルボレート塩、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。
【００２８】
これらの硬化触媒は、用途によっては２種以上を併用してもよく、その添加量はエポキシ樹脂（Ａ）１００重量部に対して０．１〜１０重量部の範囲が望ましい。
【００２９】
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特に好ましく使用される。
【００３０】
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。この非晶性シリカは公知の任意の方法で製造方法でき、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。
【００３１】
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、球状溶融シリカを全充填材（Ｃ）中に９０重量％以上含有することが特に好ましい。
【００３２】
充填材（Ｃ）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。
【００３３】
本発明で使用するシランカップリング剤（Ｄ）は、アミノ基が全て２級であるアミノシランカップリング剤（Ｄ−１）とＤ−１以外のシランカップリング剤（Ｄ−２）の少なくとも２種を含有する。シランカップリング剤（Ｄ）中のアミノシランカップリング剤（Ｄ−１）とシランカップリング剤（Ｄ−２）との割合は、重量比で（Ｄ−１）／（Ｄ−２）＝３／９７〜９７／３とすることが必要であり、１０／９０〜９０／１０が好ましく、４０／６０〜９０／１０の範囲とするのがさらに好ましい。
【００３４】
シランカップリング剤（Ｄ−１）および（Ｄ−２）のいずれかを単独使用する場合には、半田付け行程におけるクラックの防止効果および流動性、硬化性、ボイドなどの成形性向上効果が発揮されない。シランカップリング剤（Ｄ−１）および（Ｄ−２）を上記の範囲内で併用することにより、初めて膨れ性のみならず流動性、硬化性、ボイドなどの成形性向上効果を得ることができ、バランスの取れた組成物とすることができる。
【００３５】
シランカップリング剤（Ｄ）の各成分（Ｄ−１）と（Ｄ−２）は予め混合物として添加しても、個々に添加してもよく、またあらかじめ樹脂組成物に含まれるほかの成分と混合することも、反応させて用いることもできる。
【００３６】
ここでアミノ基が全て２級であるアミノシランカップリング剤（Ｄ−１）の具体的な例としては、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およびγ−（Ｎ−エチルアミノ）プロピルメチルジメトキシシランなどが挙げられる。
【００３７】
Ｄ−１に定義されるシランカップリング剤のなかでも、耐湿信頼性と流動性の点から、特にγ−（Ｎ−フェニルアミノ）プロピルトリメトキシシランが好ましく使用される。
【００３８】
アミノシランカップリング剤（Ｄ−１）以外のシランカップリング剤（Ｄ−２）としては、ケイ素原子に結合した有機基が、炭化水素基、ならびにエポキシ基、１級アミノ基、３級アミノ基、（メタ）アクリロイル基、メルカプト基などを有する炭化水素基であるものが例示される。
【００３９】
シランカップリング剤（Ｄ−２）の具体例としては、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−（Ｎ−エチルアミノ）プロピルメチ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、γ−メルカトプロピルトリメトキシシラン、γ−メルカト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などが挙げられる。これらのなかでも、耐リフロー信頼性の点から、１級アミノ基を有する有機基がケイ素原子に結合したシランカップリング剤が好ましく使用され、このようなものとしてはγ−アミノプロピルトリメトキシシランおよび、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などがある。
【００４０】
シランカップリング剤（Ｄ）の配合割合としてはエポキシ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。
【００４１】
本発明では、必須成分ではないが難燃性を向上させる目的でブロム化合物を配合できる。ブロム化合物は、通常、エポキシ樹脂組成物に難燃剤として添加されるものであれば、特に限定されない。ブロム化合物の好ましい具体例としては、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が、成形性の点から特に好ましい。
【００４２】
同様に、本発明のエポキシ樹脂組成物では、必須成分ではないがアンチモン化合物を配合できる。これは通常半導体封止用エポキシ樹脂組成物に難燃助剤として添加されるもので、特に限定されず、公知のものが使用できる。アンチモン化合物の好ましい具体例としては、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。
【００４３】
これら難燃剤、難燃助剤を添加する場合、エポキシ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信頼性の観点からハロゲン原子およびアンチモン原子それぞれが、エポキシ樹脂組成物に対して０．２重量％以下、さらには実質的に配合されていないことが好ましい。
【００４４】
本発明のエポキシ樹脂組成物は、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、ポリエチレン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、長鎖脂肪酸、長鎖脂肪酸の金属塩、長鎖脂肪酸のエステル、長鎖脂肪酸のアミドおよびパラフィンワックスなどの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。
【００４５】
本発明のエポキシ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。
【００４６】
本発明のエポキシ樹脂組成物は、加熱混練で溶融し、冷却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。
【００４７】
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。
【００４８】
【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。
【００４９】
[実施例１〜８、比較例１〜７]
表１に示した成分を表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樹脂組成物を得た。
【００５０】
【表１】

【００５１】
【化８】

【００５２】
【化９】

【００５３】
【化１０】

【００５４】
【化１１】

【００５５】
【化１２】

【００５６】
【化１３】

【００５７】
【化１４】

【００５８】
【化１５】

【００５９】
＜膨れ特性（耐リフロー信頼性）評価＞
得られた樹脂組成物について１４４ｐｉｎＴＱＦＰ（外形：２０ｍｍ×２０ｍｍ×１．０ｍｍ、フレーム材料：銅）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１分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模擬素子を搭載した、チップサイズ８ｍｍ×８ｍｍ×０．３ｍｍのものを用いた。
【００６０】
上記成形により得られた１４４ｐｉｎＴＱＦＰのパッケージ１０個を１８０℃、６時間の条件でポストキュアーした後、マイクロメーターにてパッケージ中央部の厚みＩ（μm）を計測した。これを８５℃／６０％ＲＨで２４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。
パッケージがリフロー炉を出た５秒後、再びマイクロメーターにてパッケージの中央部の厚みII（μm）を計測した。さらに１０個それぞれのパッケージについて（厚みII−厚みＩ）を算出し、この１０個の平均値を「膨れ」（μm）とした。なお、膨れは小さい方が好ましく、８０μｍ以下であることが特に好ましい。
【００６１】
＜硬化性の評価＞
低圧トランスファー成型法により直径５ｃｍ厚さ３．３ｍｍの円盤を、金型表面温度１７５℃、トランスファー圧力３０ｋｇ／ｃｍ²で成形し、熱時硬度（バーコール）を測定した。熱時硬度が６０を超えるキュアー時間を硬化性（sec）とした。
【００６２】
＜密着性不良率＞
膨れ特性の評価と同様の方法で同様の１４４ｐｉｎＴＱＦＰのパッケージを２０個成形、１８０℃、６時間の条件でポストキュアーし、これを８５℃／６０％ＲＨで２４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。
【００６３】
こののち、リードフレームの銀メッキ部、チップ表面、ステージ裏面の剥離状況を超音波探傷器（日立建機（株）製「ｍｉ−ｓｃｏｐｅ１０」）で観察し、それぞれについて剥離の発生したパッケージ数を調べた。
【００６４】
＜成形性（パッケージ充填性）評価＞
上記成形により得られた１４４ｐｉｎＴＱＦＰ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、ステージ変位・未充填の有無を調べた。ステージ変位・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。ステージ変位についてはパッケージゲート部とベント部の傾きが１００μｍ以上のものを不良とした。
【００６５】
【表２】

【００６６】
【表３】

【００６７】
表２〜３に評価結果を示す。表２〜３に見られるように１〜４のシランカップリング剤を単独で使用すると、硬化性、成形性、あるいはリフロー時の密着性が不十分である（比較例１〜４）。エポキシ樹脂として一般式（Ｉ）で表されるテトラメチルビスフェノールＦ型エポキシ樹脂を使用しなかった場合、膨れ特性、密着性が不十分である（比較例５〜７）。それに対し、本発明のエポキシ樹脂組成物はリフロー時の密着性、膨れ特性、パッケージ充填性、硬化性のいずれも優れている。
【００６８】
【発明の効果】
以上説明したように、本発明によればリフロー時の密着性、膨れ特性などの耐リフロー信頼性、成形時の充填性および硬化性が優れた半導体封止用エポキシ樹脂組成物及び該エポキシ樹脂組成物によって封止してなる半導体装置を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an epoxy resin composition that is excellent in reflow resistance reliability and moldability and is particularly suitable for semiconductor encapsulation.
[0002]
[Prior art]
As sealing methods for electronic circuit components such as semiconductor devices, resin sealing using phenolic resin, silicone resin, epoxy resin, etc. has been proposed as well as hermetic sealing using metal or ceramics. The resin used is called a sealing material resin. Among them, resin sealing with an epoxy resin is most actively performed from the viewpoint of the balance between economy, productivity, and physical properties. As a sealing method using an epoxy resin, a method in which a composition obtained by adding a curing agent, a filler or the like to an epoxy resin is used, and a semiconductor element is set in a mold and sealed by a transfer molding method or the like. It has been broken.
[0003]
Recently, high density and automation have been promoted in mounting semiconductor device packages on printed circuit boards. Instead of the conventional “insertion mounting method” in which lead pins are inserted into holes in the substrate, the semiconductor device packages are soldered to the substrate surface. “Surface mounting method” has become popular. Accordingly, semiconductor device packages are also shifting from conventional DIP (dual in-line package) to thin FPP (flat plastic package) suitable for high-density mounting and surface mounting. Among them, recently, TSOP, TQFP, and LQFP having a thickness of 2 mm or less are becoming mainstream due to advances in microfabrication technology. Therefore, it becomes more susceptible to external influences such as humidity and temperature, and reliability such as reflow reliability, high temperature reliability and moisture resistance reliability will become increasingly important in the future. In particular, recently, improvement in reflow resistance reliability in packages having a thickness of 1 mm or less such as TSOP and TQFP has been demanded.
[0004]
In surface mounting, mounting is usually performed by solder reflow. In this method, semiconductor device packages are placed on a substrate, and these are exposed to a high temperature of 200 ° C. or higher, and solder previously applied to the substrate is melted to adhere the semiconductor device package to the substrate surface. In such a mounting method, the entire semiconductor device package is exposed to a high temperature. Therefore, if the hygroscopic property of the sealing resin is high, peeling between the sealing resin and the semiconductor chip or between the sealing resin and the lead frame may occur. A phenomenon occurs in which moisture that has absorbed moisture explodes during solder reflow and cracks occur. In the case of a thin package, the silver paste layer absorbs moisture and peels off from the interface with the silicon chip or the lead frame during reflow, and the bottom of the package is pushed down to cause the bottom of the package to swell (swelling characteristics). Furthermore, in recent years, the use of lead-free solder containing no lead has been promoted from the viewpoint of environmental protection. However, lead-free solder has a high melting point, which increases the reflow temperature, resulting in higher reflow resistance 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 reliability. It is because hygroscopicity falls by reducing the resin component in a sealing resin composition. However, if the ratio of the filler in the sealing resin composition is simply increased, the fluidity is deteriorated and problems such as package unfilling and stage shift occur.
[0006]
Therefore, in order to improve the reflow resistance reliability, an epoxy resin composition containing tetramethylbisphenol F type epoxy resin as an epoxy resin and phenol aralkyl resin as a curing agent and containing 25 to 93% by weight of a filler has been proposed. (Japanese Patent Laid-Open No. 8-134183), although the effect is as it is, it is still not sufficient. Furthermore, there is a demand for a resin composition that is further excellent in reflow reliability, particularly in a bulging property in a package having a thickness of 1 mm or less.
[0007]
In this way, while requiring higher reflow resistance reliability than ever, requirements for moldability such as package fillability and curability at the time of molding are becoming stricter, and an excellent composition also in these respects Things are getting demanded.
[0008]
[Problems to be solved by the invention]
An object of the present invention has been made in view of the above circumstances, and is an epoxy resin that is excellent in reflow resistance reliability at a higher reflow temperature and excellent in moldability such as package fillability and curability during molding. An object is to provide a composition and a semiconductor device formed by sealing with the epoxy resin composition.
[0009]
[Means for Solving the Problems]
The inventors of the present invention have reached the present invention as a result of intensive studies to achieve the above-mentioned object.
[0010]
The present invention mainly has the following configuration. That is,
“An epoxy resin composition containing an epoxy resin (A), a curing agent (B), an inorganic filler (C) and a silane coupling agent (D), wherein the epoxy resin (A) has the following formula (I) And an aminosilane coupling agent (D-1) of 3 to 97% by weight, wherein the amino group is secondary, and the tetrasilanebisphenol F type epoxy resin represented by An epoxy resin composition comprising 97 to 3% by weight of a silane coupling agent (D-2) other than D-1.
[0011]
[Formula 4]

Is.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0013]
The present invention contains an epoxy resin (A), a curing agent (B), a filler (C), and a silane coupling agent (D) as essential components.
[0014]
In the present invention, the epoxy resin (A) contains a tetramethylbisphenol F-type epoxy resin represented by the following general formula (I) as an essential component.
[0015]
[Chemical formula 5]

[0016]
By containing the tetramethylbisphenol F type epoxy resin represented by the general formula (I) in the epoxy resin, the swelling characteristics at the time of reflow are improved, and the effect of lowering the viscosity and improving the moldability is also obtained. The content of the tetramethylbisphenol F type epoxy resin epoxy resin (a) represented by the general formula (I) is preferably 10% by weight or more based on the total amount of the epoxy resin (A), and is based on the total amount of the epoxy resin (A). More preferably, it is 50% by weight or more.
[0017]
Depending on the application, an epoxy resin other than the epoxy resin represented by formula (I) may be used in combination. Other epoxy resins are not particularly limited as long as they are compounds having two or more epoxy groups in one molecule, and they are monomers, oligomers, and polymers in general. For example, bisphenol F type epoxy resin having no alkyl substituent, cresol novolac type epoxy resin, phenol novolac 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 resins such as 4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetrabutylbiphenyl, phenol aralkyl type epoxy resins, naphthalene type epoxy resins, bisphenol A type epoxy resins, Triphenol type epoxy resin, dicyclopentadiene skeleton-containing epoxy resin, triphenyl meta Type epoxy resins, and halogenated epoxy resins. Two or more kinds of other epoxy resins may be used.
[0018]
When two or more types of epoxy resins are used in combination, the content of the epoxy resin represented by the general formula (I) is 10% relative to the total amount of the epoxy resin (A) because the effect of the addition is enhanced from the viewpoint of improving the swelling characteristics. % By weight or more is preferable, and more preferably 50% by weight or more based on the total amount of the epoxy resin (A).
[0019]
The compounding quantity of an epoxy resin (A) is 0.5 to 10 weight% normally with respect to the whole epoxy resin composition, 1 to 6 weight% is especially preferable.
[0020]
The curing agent (B) in the present invention is not particularly limited as long as it is cured by reacting with an epoxy resin. Specific examples thereof include novolak resins such as phenol novolak, cresol novolak, 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, acid anhydrides such as maleic anhydride, phthalic anhydride, pyromellitic anhydride, and metaphenylenediamine, Examples include aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone, and these may be used alone or in combination of two or more curing agents. The melt viscosity of the curing agent (B) is preferably 1 Pa · s or less, more preferably 0.3 Pa · s or less in terms of ICI (150 ° C.) viscosity.
[0021]
As the curing agent (B), a phenol aralkyl resin represented by the following general formula (II) is particularly preferably used from the viewpoint of reflow reliability, and more preferably a p-xylene type phenol represented by the following general formula (III). Aralkyl resin is good.
[0022]
[Chemical 6]

[0023]
[Chemical 7]

[0024]
When two or more curing agents are used in combination, the content of the curing agent represented by the general formula (II) is preferably 10% by weight or more, more preferably 20% by weight or more based on the total amount of the curing agent (B). Further preferred.
[0025]
When two or more kinds of curing agents are used in combination, the content of the curing agent represented by the general formula (III) is more preferably 10% by weight or more based on the total amount of the curing agent (B) from the viewpoint of improving swelling characteristics. 20% by weight or more is more preferable.
[0026]
The compounding quantity of a hardening | curing agent (B) is 0.5 to 10 weight% normally with respect to the whole epoxy resin composition, and especially 1 to 6 weight% is preferable. Furthermore, the compounding 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. in terms of mechanical properties and moisture resistance. 5, in particular in the range of 0.6 to 1.3.
[0027]
In the present invention, a curing catalyst may be used to accelerate the curing reaction between the epoxy resin (A) and the curing agent (B). The curing catalyst is not particularly limited as long as it accelerates the curing reaction. For example, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4- Imidazole compounds such as methylimidazole and 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzylmethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1 , 8-diazabicyclo (5,4,0) undecene-7 and other tertiary amine compounds, zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum, etc. Organic metal phosphine compounds such as organometallic compounds and triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salts, trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine It is done. Of these, organic phosphine compounds are preferable from the viewpoint of reliability and moldability, and triphenylphosphine is particularly preferably used.
[0028]
These curing catalysts may be used in combination of two or more depending on the application, and the addition amount is desirably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin (A).
[0029]
The filler (C) in the present invention is preferably an inorganic filler, 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 reducing the coefficient of linear expansion and is effective in reducing stress. As the shape, a crushed shape or a spherical shape is used, and a spherical shape is particularly preferably used from the viewpoint of fluidity.
[0030]
Amorphous silica as used herein generally means one having a true specific gravity of 2.3 or less. The amorphous silica can be produced by any known method. For example, a method of melting crystalline silica, a method of oxidizing metal silicon, a method of synthesis from various raw materials such as hydrolysis of alkoxysilane can be used.
[0031]
Among amorphous silicas, spherical fused silica produced by melting quartz is particularly preferably used, and it is particularly preferred that spherical fused silica is contained in the total filler (C) by 90% by weight or more.
[0032]
The particle size and particle size distribution of the filler (C) are not particularly limited, but the average particle size (meaning median diameter; the same applies hereinafter) is 5 to 30 μm from the viewpoint of fluidity and burr reduction during molding. It is preferable that it exists in the range. Two or more fillers having different average particle sizes or particle size distributions can be combined.
[0033]
The silane coupling agent (D) used in the present invention is at least two of an aminosilane coupling agent (D-1) whose amino groups are all secondary and a silane coupling agent (D-2) other than D-1. Containing. The ratio of the aminosilane coupling agent (D-1) and the silane coupling agent (D-2) in the silane coupling agent (D) is (D-1) / (D-2) = 3 / in weight ratio. It is necessary to set it as 97-97 / 3, 10 / 90-90 / 10 are preferable and it is more preferable to set it as the range of 40 / 60-90 / 10.
[0034]
When one of the silane coupling agents (D-1) and (D-2) is used alone, the effect of preventing cracks in the soldering process and the effect of improving moldability such as fluidity, curability and voids are exhibited. Not. By combining the silane coupling agents (D-1) and (D-2) within the above range, it is possible to obtain not only swelling but also moldability improvement effects such as fluidity, curability and voids for the first time. , A balanced composition can be obtained.
[0035]
Each component (D-1) and (D-2) of the silane coupling agent (D) may be added in advance as a mixture or individually, and other components included in the resin composition in advance. They can be mixed or reacted for use.
[0036]
Specific examples of the aminosilane coupling agent (D-1) in which all amino groups are secondary include γ- (N-phenylamino) propyltrimethoxysilane and γ- (N-phenylamino) propylmethyl. Dimethoxysilane, γ- (N-methylamino) propyltrimethoxysilane, γ- (N-methylamino) propylmethyldimethoxysilane, γ- (N-ethylamino) propyltrimethoxysilane and γ- (N-ethylamino) Examples include propylmethyldimethoxysilane.
[0037]
Among the silane coupling agents defined in D-1, γ- (N-phenylamino) propyltrimethoxysilane is particularly preferably used from the viewpoint of moisture resistance reliability and fluidity.
[0038]
As the silane coupling agent (D-2) other than the aminosilane coupling agent (D-1), an organic group bonded to a silicon atom is a hydrocarbon group, an epoxy group, a primary amino group, a tertiary amino group, Examples are hydrocarbon groups having (meth) acryloyl groups, mercapto groups, and the like.
[0039]
Specific examples of the silane coupling agent (D-2) include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ- (2,3-epoxycyclohexyl) propyltrimethoxysilane. , Γ-glycidoxypropyltrimethoxysilane, γ- (N-ethylamino) propylmethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxy Silane, γ-mercaptopropylmethyldimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- ( Aminoethyl) -γ-aminopropyltriethyl Run, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ- (N, N-dimethylamino) propyltrimethoxysilane, etc. Is mentioned. Among these, from the viewpoint of reflow resistance reliability, a silane coupling agent in which an organic group having a primary amino group is bonded to a silicon atom is preferably used, such as γ-aminopropyltrimethoxysilane and N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane.
[0040]
The blending ratio of the silane coupling agent (D) is preferably 0.1 to 2% by weight based on the total amount of the epoxy resin composition in terms of fluidity and filling properties.
[0041]
In the present invention, although not an essential component, a bromine compound can be blended for the purpose of improving flame retardancy. The bromine compound is not particularly limited as long as it is normally added as a flame retardant to the epoxy resin composition. Preferred specific examples of the bromo compound include brominated epoxy resins such as brominated bisphenol A type epoxy resin and brominated phenol novolac type epoxy resin, brominated polycarbonate resin, brominated polystyrene resin, brominated polyphenylene oxide resin, tetrabromobisphenol. A, decabromodiphenyl ether, and the like. Among them, brominated epoxy resins such as brominated bisphenol A type epoxy resins and brominated phenol novolac type epoxy resins are particularly preferable from the viewpoint of moldability.
[0042]
Similarly, in the epoxy resin composition of the present invention, an antimony compound can be blended although it is not an essential component. This is usually added as a flame retardant aid to the epoxy resin composition for semiconductor encapsulation, and is not particularly limited, and known ones can be used. Preferable specific examples of the antimony compound include antimony trioxide, antimony tetraoxide, and antimony pentoxide.
[0043]
When these flame retardants and flame retardant aids are added, halogen atoms and antimony atoms are added to the epoxy resin composition from the viewpoint of easy disposal of unnecessary materials generated from the epoxy resin composition and reliability of the semiconductor device. On the other hand, it is preferably 0.2% by weight or less, and further substantially not blended.
[0044]
The epoxy 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, silicone rubber, olefin copolymers, various elastomers such as modified nitrile rubber and modified polybutadiene rubber, various thermoplastic resins such as silicone oil and polyethylene, fluorine based, silicone Surfactants such as long-chain fatty acids, metal salts of long-chain fatty acids, esters of long-chain fatty acids, various release agents such as long-chain fatty acid amides and paraffin wax, and ion-trapping agents such as hydrotalcites, organic Crosslinkers such as peroxides.
[0045]
The epoxy resin composition of the present invention is preferably produced by melt kneading the above components. For example, various raw materials are mixed by a known method such as a mixer and then melt kneaded using a known kneading method such as a Banbury mixer, a kneader, a roll, a single or twin screw extruder and a kneader. As the resin temperature at the time of melt kneading, a range of 70 to 150 ° C. is usually used.
[0046]
The epoxy resin composition of the present invention is a powder shape melted by heat kneading, cooled and pulverized, a tablet shape obtained by tableting the powder, a tablet shape melted by heat kneading and cooled and solidified in a mold, It can be used in the form of pellets that have been melted by heat kneading, extruded, and further cut.
[0047]
From these shapes, the semiconductor device is manufactured by sealing the semiconductor element. The epoxy resin composition of the present invention is formed on a member having a semiconductor fixed on a substrate by a method such as transfer molding, injection molding, or casting at a temperature of 120 to 250 ° C., preferably 150 to 200 ° C. Thus, a semiconductor device sealed with a cured product of the epoxy resin composition is manufactured. Moreover, additional heat processing (For example, 150-200 degreeC, 2 to 16 hours) can be performed as needed.
[0048]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples given here. In addition,% in an Example shows weight%.
[0049]
[Examples 1-8, Comparative Examples 1-7]
The components shown in Table 1 were dry blended with a mixer at the composition ratio (weight ratio) shown in Tables 2 to 3, and then heated and kneaded for 5 minutes using a mixing roll with a roll surface temperature of 90 ° C., and then cooled and ground. An epoxy resin composition for semiconductor encapsulation was obtained.
[0050]
[Table 1]

[0051]
[Chemical 8]

[0052]
[Chemical 9]

[0053]
[Chemical Formula 10]

[0054]
Embedded image

[0055]
Embedded image

[0056]
Embedded image

[0057]
Embedded image

[0058]
Embedded image

[0059]
<Swelling characteristics (reflow resistance reliability) evaluation>
Using the mold for 144 pin TQFP (outer shape: 20 mm × 20 mm × 1.0 mm, frame material: copper), the obtained resin composition is packaged under the conditions of a mold temperature of 175 ° C. and a cure time of 1 minute. Was molded. As the evaluation chip, a chip having a chip size of 8 mm × 8 mm × 0.3 mm, on which a simulated element having a silicon nitride film coated, was used.
[0060]
Ten 144 pin TQFP packages obtained by the above molding were post-cured under conditions of 180 ° C. and 6 hours, and then the thickness I (μm) of the central portion of the package was measured with a micrometer. This was humidified at 85 ° C./60% RH for 24 hours and then heat-treated in an IR reflow furnace having a maximum temperature of 260 ° C. The temperature profile of the reflow furnace is such that the region of 150 ° C. to 200 ° C. is 60 seconds to 100 seconds, the 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 ˜265 ° C. for 10 to 20 seconds, and the temperature decrease rate from 260 ° C. to 200 ° C. was set to 1.5 to 2.5 ° C./second.
Five seconds after the package exited the reflow furnace, the thickness II (μm) of the central portion of the package was again measured with a micrometer. Further, (thickness II−thickness I) was calculated for each of the 10 packages, and the average value of the 10 packages was defined as “swell” (μm). In addition, the one where a swelling is small is preferable and it is especially preferable that it is 80 micrometers or less.
[0061]
<Evaluation of curability>
A disk having a diameter of 5 cm and a thickness of 3.3 mm was molded by a low-pressure transfer molding method at a mold surface temperature of 175 ° C. and a transfer pressure of 30 kg / cm ² , and the hot hardness (Barcoal) was measured. Curing time with a hot hardness exceeding 60 was defined as curability (sec).
[0062]
<Adhesion failure rate>
20 identical 144pinTQFP packages were molded in the same way as the evaluation of the blistering characteristics, post-cured at 180 ° C for 6 hours, and humidified at 85 ° C / 60% RH for 24 hours, and then the maximum temperature of 260 ° C. Heat treatment was performed in an IR reflow furnace. The temperature profile of the reflow furnace is such that the region of 150 ° C. to 200 ° C. is 60 seconds to 100 seconds, the 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 ˜265 ° C. for 10 to 20 seconds, and the temperature decrease rate from 260 ° C. to 200 ° C. was set to 1.5 to 2.5 ° C./second.
[0063]
After that, the state of peeling of the silver plating part of the lead frame, the chip surface, and the back of the stage was observed with an ultrasonic flaw detector (“mi-scope 10” manufactured by Hitachi Construction Machinery Co., Ltd.), and the number of packages where peeling occurred was measured for each. Examined.
[0064]
<Evaluation of formability (package fillability)>
Ten 144-pin TQFP packages obtained by the above molding were visually observed and cut in cross section after molding, and then observed using a 20-fold microscope to examine whether the stage was displaced or not filled. The number of well-obtained packages was determined excluding defective packages where stage displacement / unfilling occurred. Regarding the stage displacement, those having an inclination of 100 μm or more between the package gate portion and the vent portion were regarded as defective.
[0065]
[Table 2]

[0066]
[Table 3]

[0067]
Tables 2 to 3 show the evaluation results. As seen in Tables 2-3, when 1-4 silane coupling agents are used alone, the curability, moldability, or adhesion during reflow is insufficient (Comparative Examples 1-4). When the tetramethylbisphenol F-type epoxy resin represented by the general formula (I) is not used as the epoxy resin, the swelling characteristics and adhesion are insufficient (Comparative Examples 5 to 7). On the other hand, the epoxy resin composition of the present invention is excellent in all of adhesion, swelling characteristics, package fillability, and curability during reflow.
[0068]
【Effect of the invention】
As described above, according to the present invention, an epoxy resin composition for semiconductor encapsulation excellent in reflow resistance reliability such as adhesion during reflow and swelling characteristics, filling property and curability during molding, and the epoxy resin composition A semiconductor device formed by sealing with an object can be obtained.

Claims (4)

An epoxy resin composition containing an epoxy resin (A), a curing agent (B), an inorganic filler (C) and a silane coupling agent (D), wherein the epoxy resin (A) is represented by the following formula (I) 3 to 97% by weight of an aminosilane coupling agent (D-1) containing the tetramethylbisphenol F type epoxy resin represented, and the silane coupling agent (D) is all secondary amino groups, and D -1 than the silane coupling agent (D-2) 97~3 wt% Tona is, a silane coupling agent (D-2) is a silane coupling agent organic group is bonded to a silicon atom having a primary amino group in a γ- aminopropyltrimethoxysilane or N-beta-(aminoethyl)-.gamma.-aminopropyltrimethoxysilane epoxy resin composition characterized essential components to Rukoto.

The epoxy resin composition according to claim 1, wherein the curing agent (B) contains a compound represented by the following formula (II).

The epoxy resin composition according to claim 1, wherein the curing agent (B) contains a compound represented by the following formula (III).

And wherein a sealed by the cured product of the epoxy resin composition according to any one of claims 1-3.