JP5087814B2 - Epoxy resin composition and semiconductor device - Google Patents

Description

」である。
【００１１】
【発明の実施の形態】
以下に本発明を詳細に説明する。
【００１２】
本発明に用いられるエポキシ樹脂（Ａ）は、一般式（Ｉ）のビスフェノールＦ型エポキシ樹脂を含有するものであり、好ましくは一般式（Ｉ）のビスフェノールＦ型エポキシ樹脂を全エポキシ樹脂中に１０重量％以上含むエポキシ樹脂である。
【００１３】
一般式（Ｉ）で表されるエポキシ樹脂の具体例を以下に示すが、これらに限定されるものではない。
【００１４】
【化３】

エポキシ樹脂（Ａ）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する。
【００１５】
一般式（Ｉ）で表されるテトラメチルビスフェノールＦ型エポキシ樹脂は、全エポキシ樹脂中に１０重量％以上含まれることが好ましい。１０重量％以上とすると低粘度化の効果が大きく、充填材を多量に配合させることができ、樹脂組成物の硬化物の吸湿量が小さくなる。そのため、半導体パッケージのリフロー時の膨れ特性が向上し、又、成形時の溶融粘度も小さくなり、特に薄型半導体パッケージへの充填性が向上するので好ましい。さらに、一般式（Ｉ）で表されるテトラメチルビスフェノールＦ型エポキシ樹脂の含有量は、エポキシ樹脂（Ａ）全量に対して３０重量％以上がさらに好ましく、６０重量％以上であることがよりいっそう好ましい。
【００１６】
本発明のエポキシ樹脂（Ａ）は、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よい。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、エポキシ基を有するモノマー、オリゴマー、ポリマー全般を指し、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、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、ビスフェノールＡ型エポキシ樹脂、オルソクレゾールノボラック型エポキシ樹脂、ジシクロペンタジエン変性フェノール型エポキシ樹脂、トリフェノール型エポキシ樹脂、トリフェノールメタン型エポキシ樹脂、ナフトール型エポキシ樹脂、およびハロゲン化エポキシ樹脂などが挙げられる。又、これらのエポキシ樹脂は、単独もしくは混合して用いてもよい。
【００１７】
本発明に用いられる硬化剤（Ｂ）は、エポキシ樹脂（Ａ）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。
【００１８】
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。
【００１９】
【化４】

【００２０】
【化５】

【００２１】
２種以上の硬化剤を併用する場合、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％以上であることがさらに好ましい。
【００２２】
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。
【００２３】
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０．７〜１．３の範囲にあることが好ましい。
【００２４】
本発明に用いられる充填材（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。
【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。
【００２６】
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い。
【００２７】
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。
【００２８】
充填材（Ｃ）の配合量としては成形性、耐半田リフロー性の点から８０〜９５重量％が好ましい。
【００２９】
樹脂組成物全体における充填材の割合を高めると難燃性が高くなり、従来使用されていた難燃剤を使用しなくても難燃性を維持することができる。このことにより、従来から難燃剤として使用してきたハロゲン成分を封止材成分に添加する必要がなくなり、環境保護の点で好ましい。
【００３０】
本発明に用いられるシランカップリング剤（Ｄ）は、一級、二級および三級のアミノシランからなる群から選択される少なくとも一種を５重量％以上含有するものである。これらのカップリング剤をシランカップリング剤（Ｄ）中に５重量％以上含有させることにより、リフロー時のリードフレーム銀メッキ部の密着性が向上する。これらのカップリング剤は充填材にあらかじめ表面処理しても構わないが、単に他の構成成分とブレンドするだけでも効果を発現できる。
【００３１】
一級アミノシランとしては、例えば、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルジメトキシシラン、γ−アミノプロピルトリエトキシシラン、γ−アミノプロピルジエトキシシラン等が、二級アミノシランとしては、例えば、Ｎ−フェニル−γ−アミノプロピルトリメトキシシラン、Ｎ−フェニル−γ−アミノプロピルジメトキシシラン、Ｎ−フェニル−γ−アミノプロピルトリエトキシシラン、Ｎ−フェニル−γ−アミノプロピルジエトキシシラン等が、三級アミノとしては、例えば、γ−ジブチルアミノプロピルトリメトキシシラン、γ−ジブチルアミノプロピルジメトキシシラン、γ−ジブチルアミノプロピルトリエトキシシラン、γ−ジブチルアミノプロピルジエトキシシラン等が挙げられるが、これらに限定されるものでははい。又、上記シランカップリング剤は単独、もしくは混合して用いても良い。併用する他のカップリング剤としては、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−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等が挙げられる。
【００３２】
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。
【００３３】
本発明に用いられる硬化促進剤（Ｅ）は、アミジン化合物を含有する。アミジン化合物は、エポキシ樹脂（Ａ）と硬化剤（Ｂ）との硬化反応を促進するとともに、更にその塩基性の強さからエポキシ樹脂中のエポキシ基同士の開環重合の開始触媒としても作用することが特徴である。アミジン化合物としては、例えば、１，８−ジアザビシクロ（５，４，０）ウンデセン−７、１，５−ジアザビシクロ（４，３，０）ノネン−５、６−ジブチルアミノ−１，８−ジアザビシクロ（５，４，０）ウンデセン−７、７−メチル−１，５，７−トリアザビシクロ（４，４，０）デセン−５等が挙げられるが、これらに限定されるものではない。又、上記群の化合物は、１，８−ジアザビシクロ（５，４，０）ウンデセン−７・テトラフェニルボレート等の無機酸或いは有機酸との塩の形でも使用できる。又、これらは単独でも混合して用いても良い。又、エポキシ基の開環重合を促進することはできないが、エポキシ基とフェノール性水酸基との付加反応を促進することができる他の硬化促進剤と併用しても良い。併用する他の硬化促進剤としては、例えば、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挙げられる。硬化剤促進剤（Ｅ）の配合量としてはエポキシ樹脂組成物全体に対して通常０．０２〜１．０重量％、特に０．０５〜０．５重量％が好ましい。また、硬化促進剤（Ｅ）を他の硬化促進剤と併用する場合は、硬化促進剤（Ｅ）が硬化促進剤全体に対して５０重量％以上が好ましく、特に８０重量％以上が好ましい。
【００３４】
本発明のエポキシ樹脂組成物は、（Ａ）〜（Ｅ）の成分の他、必須成分ではないが必要性に応じて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。
【００３５】
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。
【００３６】
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％以下が好ましい。
【００３７】
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が適宜配合可能である。
【００３８】
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。
【００３９】
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。
【００４０】
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。
【００４１】
【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。
【００４２】
[実施例１、２、４〜１０、比較例１〜４]
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。
【００４３】
【表１】

【００４４】
【化６】

【００４５】
【化７】

【００４６】
＜膨れ特性評価＞
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：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。
【００４７】
上記成形により得られた１４４ｐｉｎＴＱＦＰのパッケージ１０個を１７５℃、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を連続で２回行った。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。
【００４８】
＜Ａｇメッキ密着性（銀メッキ剥離数）評価＞
得られた樹脂組成物について４８ｐｉｎＴＳＯＰ（外形：１２ｍｍ×１８ｍｍ×１．０ｍｍ、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４ｍｍ×６ｍｍ×０．３ｍｍのものを用いた。
【００４９】
上記成形により得られた４８ｐｉｎＴＳＯＰのパッケージ３２個を１７５℃、６時間の条件でポストキュアーさせた。得られたパッケージを３０℃／６０％ＲＨで１９２時間加湿後、最高温度２６０℃のＩＲリフロー炉で加熱処理を連続で３回行った。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。超音波探傷装置を用いてインナーリード部先端の銀メッキ部と樹脂組成物との剥離が発生しているパッケージ数を測定し、剥離数（剥離発生パッケージ数／全パッケージ数）として表示した。
【００５０】
＜パラジウムメッキ密着性（パラジウムメッキ剥離数）評価＞
得られた樹脂組成物について２０８ｐｉｎＬＱＦＰ（外形：２８ｍｍ×２８ｍｍ×１．４ｍｍ、フレーム材料：パラジウムメッキフレーム）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１２．７ｍｍ×１２．７ｍｍ×０．３ｍｍのものを用いた。
【００５１】
上記成形により得られた２０８ｐｉｎＬＱＦＰのパッケージ２０個を１７５℃、６時間の条件でポストキュアーさせた。得られたパッケージを３０℃／６０％ＲＨで１９２時間加湿後、最高温度２６０℃のＩＲリフロー炉で加熱処理を連続３回行った。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。超音波探傷装置を用いてダイパッド裏面と樹脂組成物との剥離が発生しているパッケージ数を測定し、剥離数（剥離発生パッケージ数／全パッケージ数）として表示した。
【００５２】
【表２】

【００５３】
【表３】

【００５４】
表２〜３に評価結果を示す。表２〜３に見られるようにシランカップリング剤（Ｄ）が一級〜三級のいずれかのアミノシランを含有しないと銀メッキ剥離数、膨れ性が不十分である（比較例１）。さらに、シランカップリング剤（Ｄ）が一級〜三級のいずれかのアミノシランを全シランカップリング剤中５重量％以上含有しない場合も、銀メッキ剥離数、膨れ性が不十分である（比較例２）。また、一般式（Ｉ）で表されるテトラメチルビスフェノールＦ型エポキシ樹脂を用いていない場合は膨れ性が不十分であり（比較例３）、硬化促進剤（Ｅ）がアミジン化合物を用いていない場合はパラジウムメッキ剥離数、膨れ性が不十分である（比較例４）。それらに対し、本発明のエポキシ樹脂組成物はリフロー時の耐銀メッキ剥離性、耐パラジウムメッキ剥離性、膨れ特性のいずれも優れている。
【００５５】
【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耐剥離性、膨れ特性などの耐リフロー信頼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 for semiconductor encapsulation which is excellent in reflow resistance reliability and moldability and is particularly suitable for thin 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 sealing 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 is generally performed. 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, simply increasing the proportion of the filler in the sealing resin composition deteriorates the fluidity, causes problems such as package unfilling and stage shift, and leads the lead frame to the sealing resin. Since the expansion difference becomes large, the interface between the lead frame and the sealing resin peels off. In particular, the silver-plated portion and the palladium-plated frame at the tip of the lead frame inner lead have a problem that they have poor adhesion with the sealing resin and peel off.
[0006]
Therefore, in order to improve 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 is proposed. (JP-A-8-134183), however, the adhesion to the silver-plated portion and the palladium-plated frame is still insufficient. Furthermore, there is a need for a resin composition that is further excellent in reflow reliability, particularly in a bulging property in a package having a thickness of 2 mm or less.
[0007]
[Problems to be solved by the invention]
An object of the present invention has been made in view of the circumstances as described above, and is an epoxy resin composition excellent in reflow resistance reliability at a higher reflow temperature, in particular, swelling characteristics, adhesion to silver and palladium, and the It aims at providing the semiconductor device formed by sealing with an epoxy resin composition.
[0008]
[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.
[0009]
The present invention mainly has the following configuration. That is,
“An epoxy resin composition containing an epoxy resin (A), a curing agent (B), a filler (C), a silane coupling agent (D), and a curing accelerator (E), wherein the epoxy resin (A) Containing an epoxy resin represented by the following general formula (I), the silane coupling agent (D) containing at least 5% by weight of at least one selected from the group consisting of primary, secondary and tertiary aminosilanes; And the hardening accelerator (E) contains an amidine compound, The epoxy resin composition for semiconductor sealing characterized by the above-mentioned.
[0010]
[Chemical 2]

Is.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
[0012]
The epoxy resin (A) used in the present invention contains a bisphenol F-type epoxy resin of the general formula (I), and preferably 10% of the bisphenol F-type epoxy resin of the general formula (I) in all epoxy resins. An epoxy resin containing at least wt%.
[0013]
Specific examples of the epoxy resin represented by the general formula (I) are shown below, but are not limited thereto.
[0014]
[Chemical 3]

By including the tetramethylbisphenol F type epoxy resin represented by the general formula (I) in the epoxy resin (A), the swelling characteristics at the time of reflow are improved.
[0015]
The tetramethylbisphenol F type epoxy resin represented by the general formula (I) is preferably contained in the total epoxy resin by 10% by weight or more. When the content is 10% by weight or more, the effect of reducing the viscosity is large, a large amount of filler can be blended, and the moisture absorption of the cured product of the resin composition becomes small. Therefore, the swell characteristic at the time of reflow of the semiconductor package is improved, the melt viscosity at the time of molding is reduced, and the filling property to the thin semiconductor package is improved, which is preferable. Furthermore, the content of the tetramethylbisphenol F-type epoxy resin represented by the general formula (I) is more preferably 30% by weight or more, and more preferably 60% by weight or more based on the total amount of the epoxy resin (A). preferable.
[0016]
The epoxy resin (A) of the present invention may be used in combination with an epoxy resin other than the epoxy resin represented by the general formula (I) depending on applications. Other epoxy resins are not particularly limited as long as they are compounds having two or more epoxy groups in one molecule, and generally refer to monomers, oligomers, and polymers having epoxy groups, for example, bisphenol F type having no alkyl substituent 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, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5 ' -Biphenyl type epoxy resin such as tetrabutyl biphenyl, phenol aralkyl type epoxy resin, bisphenol A type epoxy resin, orthocresol novolac type Carboxymethyl resins, dicyclopentadiene-modified phenol type epoxy resins, triphenol type epoxy resins, triphenolmethane type epoxy resins, naphthol type epoxy resins, and halogenated epoxy resins. These epoxy resins may be used alone or in combination.
[0017]
The curing agent (B) used in the present invention is not particularly limited as long as it is cured by reacting with the epoxy resin (A). Specific examples thereof include phenol novolak, cresol novolak, naphthol novolak and the like. Novolac resins, phenol aralkyl resins, biphenyl skeleton-containing phenol aralkyl resins, dicyclopentadiene skeleton-containing phenol resins, naphthol aralkyl resins, bisphenol A and other bisphenol compounds, maleic anhydride, phthalic anhydride, pyromellitic anhydride, and other acid anhydrides And aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. 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.
[0018]
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.
[0019]
[Formula 4]

[0020]
[Chemical formula 5]

[0021]
When two or more curing agents are used in combination, the content of the curing agent represented by the general formula (III) 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.
[0022]
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.
[0023]
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 0.7 to 1.3.
[0024]
The filler (C) used in the present invention is preferably an inorganic filler, specifically, amorphous silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, Examples include metal oxides such as titanium oxide and antimony oxide, asbestos, glass fibers, and glass spheres. Among them, amorphous silica has a large effect of reducing the linear expansion coefficient and is preferably used because it is effective for reducing stress. It is done. 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.
[0025]
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.
[0026]
Among amorphous silicas, spherical fused silica produced by melting quartz is particularly preferable.
[0027]
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.
[0028]
The blending amount of the filler (C) is preferably 80 to 95% by weight from the viewpoints of moldability and solder reflow resistance.
[0029]
Increasing the proportion of the filler in the entire resin composition increases the flame retardancy, and the flame retardancy can be maintained without using a conventionally used flame retardant. This eliminates the need to add a halogen component that has been conventionally used as a flame retardant to the encapsulant component, which is preferable in terms of environmental protection.
[0030]
The silane coupling agent (D) used in the present invention contains 5% by weight or more of at least one selected from the group consisting of primary, secondary and tertiary aminosilanes. By containing 5% by weight or more of these coupling agents in the silane coupling agent (D), the adhesion of the lead frame silver-plated portion during reflow is improved. These coupling agents may be surface-treated on the filler in advance, but the effect can be exhibited simply by blending with other components.
[0031]
Examples of the primary aminosilane include γ-aminopropyltrimethoxysilane, γ-aminopropyldimethoxysilane, γ-aminopropyltriethoxysilane, and γ-aminopropyldiethoxysilane, and examples of the secondary aminosilane include N- Phenyl-γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyldimethoxysilane, N-phenyl-γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyldiethoxysilane, etc. are tertiary amino acids. Examples thereof include, but are not limited to, γ-dibutylaminopropyltrimethoxysilane, γ-dibutylaminopropyldimethoxysilane, γ-dibutylaminopropyltriethoxysilane, γ-dibutylaminopropyldiethoxysilane, and the like. thing Yes. The silane coupling agents may be used alone or in combination. Other coupling agents used in combination include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ- (2,3-epoxycyclohexyl) propyltrimethoxysilane, γ-methacryloxy. Examples include propyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, and the like.
[0032]
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.
[0033]
The curing accelerator (E) used in the present invention contains an amidine compound. The amidine compound accelerates the curing reaction between the epoxy resin (A) and the curing agent (B), and also acts as a catalyst for initiating ring-opening polymerization between epoxy groups in the epoxy resin due to its basic strength. It is a feature. Examples of amidine compounds include 1,8-diazabicyclo (5,4,0) undecene-7, 1,5-diazabicyclo (4,3,0) nonene-5, 6-dibutylamino-1,8-diazabicyclo ( 5,4,0) undecene-7,7-methyl-1,5,7-triazabicyclo (4,4,0) decene-5 and the like, but are not limited thereto. The compounds of the above group can also be used in the form of a salt with an inorganic acid or organic acid such as 1,8-diazabicyclo (5,4,0) undecene-7.tetraphenylborate. These may be used alone or in combination. Moreover, although ring-opening polymerization of an epoxy group cannot be promoted, it may be used in combination with another curing accelerator capable of promoting an addition reaction between an epoxy group and a phenolic hydroxyl group. Other curing accelerators used in combination include, for example, triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salt, trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) And organic phosphine compounds such as phosphine. As a compounding quantity of a hardening | curing agent accelerator (E), it is 0.02-1.0 weight% normally with respect to the whole epoxy resin composition, Especially 0.05-0.5 weight% is preferable. Moreover, when using together a hardening accelerator (E) with another hardening accelerator, 50 weight% or more is preferable with respect to the hardening accelerator (E) with respect to the whole hardening accelerator, and 80 weight% or more is especially preferable.
[0034]
In addition to the components (A) to (E), the epoxy resin composition of the present invention is not an essential component but can contain a bromine compound according to necessity. The bromine compound is not particularly limited as long as it is normally added as a flame retardant to the epoxy resin composition. Preferable specific examples of the bromine 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.
[0035]
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.
[0036]
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. The amount is preferably 0.2% by weight or less.
[0037]
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 A crosslinking agent such as a peroxide can be appropriately blended.
[0038]
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.
[0039]
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 which are melted by heat kneading, extruded and further cut.
[0040]
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.
[0041]
【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%.
[0042]
[Examples 1 , 2, 4 to 10, Comparative Examples 1 to 4]
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.
[0043]
[Table 1]

[0044]
[Chemical 6]

[0045]
[Chemical 7]

[0046]
<Swelling characteristic evaluation>
Using the mold for 144 pin TQFP (outer shape: 20 mm × 20 mm × 1.0 mm, frame material: 42 alloy), the obtained resin composition was subjected to a mold temperature of 175 ° C. and a cure time of 1 minute using a low pressure transfer molding machine. A package 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.
[0047]
Ten 144 pin TQFP packages obtained by the above molding were post-cured at 175 ° C. for 6 hours, and the thickness I (μm) at the center of the package was measured with a micrometer. This was humidified at 85 ° C./60% RH for 24 hours, and then heat-treated twice continuously 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.
[0048]
<Evaluation of Ag plating adhesion (silver plating peel number)>
About the obtained resin composition, using a 48pin TSOP (external shape: 12 mm × 18 mm × 1.0 mm, frame material: 42 alloy) mold with a low pressure transfer molding machine at a mold temperature of 175 ° C. and a cure time of 1 minute. A package was molded. As the evaluation chip, a chip having a chip size of 4 mm × 6 mm × 0.3 mm, on which a simulated element having a silicon nitride film coated thereon was used.
[0049]
Thirty-two 48-pin TSOP packages obtained by the above molding were post-cured at 175 ° C. for 6 hours. The obtained package was humidified at 30 ° C./60% 192 hours for 192 hours, and then subjected to heat treatment three times continuously 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. Using an ultrasonic flaw detector, the number of packages in which peeling between the silver-plated portion at the tip of the inner lead portion and the resin composition occurred was measured and displayed as the number of peeling (number of peeling occurrence packages / total number of packages).
[0050]
<Evaluation of Palladium Plating Adhesion (Palladium Plating Peeling Number)>
Using the mold for 208 pin LQFP (outer shape: 28 mm × 28 mm × 1.4 mm, frame material: palladium plated frame) for the obtained resin composition, the mold temperature was 175 ° C. and the cure time was 1 minute. The package was formed with. As the evaluation chip, a chip having a chip size of 12.7 mm × 12.7 mm × 0.3 mm, on which a simulated element having a silicon nitride film coated, was used.
[0051]
Twenty 208 pin LQFP packages obtained by the above molding were post-cured at 175 ° C. for 6 hours. The obtained package was humidified at 30 ° C / 60% RH for 192 hours, and then heat-treated three times continuously 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. The number of packages where peeling between the back surface of the die pad and the resin composition occurred was measured using an ultrasonic flaw detector, and displayed as the number of peeling (number of peeling occurrence packages / total number of packages).
[0052]
[Table 2]

[0053]
[Table 3]

[0054]
Tables 2 to 3 show the evaluation results. As can be seen from Tables 2 and 3, if the silane coupling agent (D) does not contain any of primary to tertiary aminosilanes, the number of silver plating peels and swelling is insufficient (Comparative Example 1). Furthermore, when the silane coupling agent (D) does not contain any of primary to tertiary aminosilanes in an amount of 5% by weight or more in the total silane coupling agent, the number of peeled silver plating and swelling are insufficient (Comparative Example). 2). Further, when the tetramethylbisphenol F type epoxy resin represented by the general formula (I) is not used, the swelling property is insufficient (Comparative Example 3), and the curing accelerator (E) does not use an amidine compound. In this case, the number of peeled palladium plating and swelling are insufficient (Comparative Example 4). On the other hand, the epoxy resin composition of the present invention is excellent in all of the anti-silver plating releasability, the palladium anti-plating property, and the swelling property during reflow.
[0055]
【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 peeling resistance and swelling characteristics during reflow, and a semiconductor encapsulated with the epoxy resin composition A device can be obtained.

Claims (3)

An epoxy resin composition for encapsulating a semiconductor used in a semiconductor device formed by encapsulating a semiconductor element fixed to a lead frame with an epoxy resin composition by transfer molding, the epoxy resin (A), a curing agent (B), and filling It contains a material (C), a silane coupling agent (D), a curing accelerator (E), an epoxy resin (A) contains an epoxy resin represented by the following general formula (I), and a silane coupling agent ( D) contains 5% by weight or more of at least one selected from the group consisting of primary, secondary and tertiary aminosilanes, and the curing accelerator (E) contains an amidine compound. Epoxy resin composition.

The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin (A) contains 10% by weight or more of the epoxy resin represented by the general formula (I). A semiconductor device formed by sealing a semiconductor element fixed to a lead frame by transfer molding using the epoxy resin composition for semiconductor sealing according to claim 1 , wherein the lead frame is a palladium-plated frame. A semiconductor device .