JP3617504B2 - Adhesive film for mounting semiconductor elements - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve resistance to heat cycle after mounting in a semiconductor device and resistance to moisture absorption reflow. SOLUTION: An adhesive agent which is used, when a semiconductor chip is mounted on an organic support substrate, and whose storage elastic modulus at 25 deg.C measured with a dynamic viscoelestic measuring instrument is 10-2,000 MPa and further the storage elastic modulus at 260 deg.C is 3-50 MPa, a double- sided adhesive film, the semiconductor device, a semiconductor chip mounted substrate using the adhesive agent, and a method for manufacturing them are provided.

Description

【００９５】
本発明では、フィラーを添加することにより、溶融粘度が大きくでき、さらにチクソトロピック性を発現できるために、上記効果をさらに大きくすることが可能となる。
【００９６】
さらに、上記の効果に加えて、接着剤の放熱性向上、接着剤に難燃性を付与、接着時の温度において適正な粘度をもたせること、表面硬度の向上等の特性も付与できる。本発明の接着フィルムを用いて半導体チップと配線板を接着させた半導体装置は、耐リフロー性、温度サイクルテスト、耐電食性、耐湿性（耐ＰＣＴ性）等に優れていた。
【００９７】
本発明でコア材に用いられる耐熱性熱可塑性フィルムは、ガラス転移温度Ｔｇが２００℃以上のポリマまたは液晶ポリマを用いたフィルムであることが好ましく、ポリイミド、ポリエーテルスルホン、ポリアミドイミド、ポリエーテルイミドまたは全芳香族ポリエステルなどが好適に用いられる。フィルムの厚みは、５〜２００μｍの範囲内で用いるのが好ましいが、限定するものではない。Ｔｇが２００℃以下の熱可塑性フィルムをコア材に用いた場合は、はんだリフロー時などの高温時に塑性変形を起こす場合があり、好ましくない。
【００９８】
本発明でコア材の両面に形成される接着剤は、接着剤の各成分を溶剤に溶解ないし分散してワニスとし、コア材となる耐熱性熱可塑性フィルム上に塗布、加熱し溶剤を除去することにより作製することができ、接着剤層をコア材となる耐熱性熱可塑性フィルム上に形成することにより三層構造の両面接着フィルムを得ることができる。接着剤の厚みは、２〜１５０μｍの範囲で用いられ、これより薄いと接着性や熱応力緩衝効果に乏しく、厚いと経済的でなくなるが、制限するものでない。
【００９９】
また、接着剤の各成分を溶剤に溶解ないし分散してワニスとし、このワニスをベースフィルム上に塗布、加熱し溶剤を除去することにより接着剤成分のみからなる接着フィルムを作製し、この接着剤成分のみからなる接着フィルムをコア材となる耐熱性熱可塑性フィルムの両面に貼り合わせることにより三層構造の両面接着フィルムを得ることもできる。ここで、接着剤成分のみからなる接着フィルムを作製するためのベースフィルムとしては、ポリテトラフルオロエチレンフィルム、ポリエチレンテレフタレートフィルム、離型処理したポリエチレンテレフタレートフィルム、ポリエチレンフィルム、ポリプロピレンフィルム、ポリメチルペンテンフィルム、ポリイミドフィルムなどのプラスチックフィルムが使用できる。プラスチックフィルムとしては、例えば、カプトン（東レ、デュポン株式会社製商品名）、アピカル（鐘淵化学工業株式会社製商品名）等のポリイミドフィルム、ルミラー（東レ、デュポン株式会社製商品名）、ピューレックス（帝人株式会社製商品名）等のポリエチレンテレフタレートフィルムなどを使用することができる。
【０１００】
ワニス化の溶剤は、比較的低沸点の、メチルエチルケトン、アセトン、メチルイソブチルケトン、２−エトキシエタノール、トルエン、ブチルセルソルブ、メタノール、エタノール、２−メトキシエタノールなどを用いるのが好ましい。また、塗膜性を向上するなどの目的で、高沸点溶剤を加えても良い。高沸点溶剤としては、ジメチルアセトアミド、ジメチルホルムアミド、メチルピロリドン、シクロヘキサノンなどが挙げられる。
【０１０１】
ワニスの製造は、無機フィラーの分散を考慮した場合には、らいかい機、３本ロール及びビーズミル等により、またこれらを組み合わせて行なうことができる。フィラーと低分子量物をあらかじめ混合した後、高分子量物を配合することにより、混合に要する時間を短縮することも可能となる。また、ワニスとした後、真空脱気によりワニス中の気泡を除去することが好ましい。
【０１０２】
上記接着剤は、コア材となる耐熱性熱可塑性フィルムまたはプラスチックフィルム等のベースフィルム上に接着剤ワニスを塗布し、加熱乾燥して溶剤を除去することにより得られるが、これにより得られる接着剤は、ＤＳＣを用いて測定した全硬化発熱量の１０〜４０％の発熱を終えた状態とするのが好ましい。溶剤を除去する際に加熱するが、この時、接着剤組成物の硬化反応が進行しゲル化してくる。その際の硬化状態が接着剤の流動性に影響し、接着性や取扱い性を適正化する。ＤＳＣ（示差走査熱分析）は、測定温度範囲内で、発熱、吸熱の無い標準試料との温度差をたえず打ち消すように熱量を供給または除去するゼロ位法を測定原理とするものであり、測定装置が市販されておりそれを用いて測定できる。樹脂組成物の反応は、発熱反応であり、一定の昇温速度で試料を昇温していくと、試料が反応し熱量が発生する。その発熱量をチャートに出力し、ベースラインを基準として発熱曲線とベースラインで囲まれた面積を求め、これを発熱量とする。室温から２５０℃まで５〜１０℃／分の昇温速度で測定し、上記した発熱量を求める。これらは、全自動で行なうものもあり、それを使用すると容易に行なうことができる。
【０１０３】
上記コア材となる耐熱性熱可塑性フィルムまたはベースフィルムに塗布し、乾燥して得た接着剤の発熱量は、つぎのようにして求める。まず、接着剤成分のみを取り出し、２５℃で真空乾燥器を用いて溶剤を乾燥させた未硬化試料の全発熱量を測定し、これをＡ（Ｊ／ｇ）とする。つぎに、塗工、乾燥した試料の発熱量を測定し、これをＢとする。試料の硬化度Ｃ（％）（加熱、乾燥により発熱を終えた状態）は、つぎの数式（１）で与えられる。
【０１０４】
Ｃ（％）＝（Ａ−Ｂ）×１００／Ａ …（１）
本発明の接着剤成分の動的粘弾性測定装置で測定した貯蔵弾性率は、２５℃で２０〜２，０００ＭＰａで、２６０℃で３〜５０ＭＰａという低弾性率であることが好ましい。貯蔵弾性率の測定は、接着剤硬化物に引張り荷重をかけて、周波数１０Ｈｚ、昇温速度５〜１０℃／分で−５０℃から３００℃まで測定する温度依存性測定モードで行った。２５℃での貯蔵弾性率が２，０００ＭＰａを超えるものでは、半導体チップとプリント配線板の熱膨張係数の差によってリフロー時に発生する応力を緩和させる効果が小さくなるためクラックを発生させてしまう。一方、貯蔵弾性率が２０ＭＰａ未満では、取扱性が悪くなる。
【０１０５】
本発明では、コア材に耐熱性熱可塑性フィルムを用いる三層構造をとることで、エポキシ基含有アクリル系共重合体とエポキシ樹脂系接着剤において、室温付近での弾性率が低いことに起因する接着フィルムの取り扱い性を容易にすることを特徴としている。すなわち、本発明の三層構造により、室温付近での剛性のない接着フィルムの位置合せ等の作業を容易に自動化することができ、しかも、本接着剤系の優れた熱応力緩和効果を発現することができる。本発明では、下記の方法により、従来の低弾性率接着フィルムの剛性の低下等による取り扱い性の点での問題を解決した。
１）コア材に耐熱性熱可塑性フィルムを配した三層構造をとることで低弾性率の接着剤をフィルム状で容易に取り扱うことができる。
２）本発明で規定したコア材となる耐熱性熱可塑性フィルムを用いることにより、リフロー時の接着フィルムの塑性変形を抑制できる。
【０１０６】
さらに、本発明では、エポキシ樹脂と高分子量樹脂とが相溶性が良く均一になっており、アクリル系共重合体に含まれるエポキシ基がそれらと部分的に反応し、未反応のエポキシ樹脂を含んで全体が架橋してゲル化するために、それが流動性を抑制し、エポキシ樹脂等を多く含む場合においても取扱い性を損なうことがない。また、未反応のエポキシ樹脂がゲル中に多数残存しているため、圧力がかかった場合、ゲル中より未反応成分がしみだすため、全体がゲル化した場合でも、接着性の低下が少なくなる。
【０１０７】
接着剤の乾燥時には、エポキシ基含有アクリル系共重合体に含まれるエポキシ基やエポキシ樹脂がともに反応するが、エポキシ基含有アクリル系共重合体は分子量が大きく、１分子鎖中にエポキシ基が多く含まれるため、反応が若干進んだ場合でもゲル化する。通常、ＤＳＣを用いて測定した場合の全硬化発熱量の１０から４０％の発熱を終えた状態、すなわちＡまたはＢステージ前半の段階でゲル化がおこる。そのため、エポキシ樹脂等の未反応成分を多く含んだ状態でゲル化しており、溶融粘度がゲル化していない場合に比べて、大幅に増大しており、取扱い性を損なうことがない。また圧力がかかった場合、ゲル中より未反応成分がしみだすため、ゲル化した場合でも、接着性の低下が少ない。さらに、接着剤がエポキシ樹脂等の未反応成分を多く含んだ状態でフィルム化できるため、接着フィルムのライフ（有効使用期間）が長くなるという利点がある。
【０１０８】
従来のエポキシ樹脂系接着剤ではＢステージの後半から、Ｃステージ状態で初めてゲル化が起こり、ゲル化が起こった段階でのエポキシ樹脂等の未反応成分が少ないため、流動性が低く、圧力がかかった場合でも、ゲル中よりしみだす未反応成分が少ないため、接着性が低下する。
【０１０９】
なお、アクリル系共重合体に含まれるエポキシ基と低分子量のエポキシ樹脂のエポキシ基の反応しやすさについては明らかではないが、少なくとも同程度の反応性を有していればよく、アクリル系共重合体に含まれるエポキシ基のみが選択的に反応するものである必要はない。
【０１１０】
なおこの場合、Ａ、Ｂ、Ｃステージは、接着剤の硬化の程度を示す。Ａステージはほぼ未硬化でゲル化していない状態であり、ＤＳＣを用いて測定した場合の全硬化発熱量の０〜２０％の発熱を終えた状態である。Ｂステージは若干硬化、ゲル化が進んだ状態であり全硬化発熱量の２０〜６０％の発熱を終えた状態である。Ｃステージはかなり硬化が進み、ゲル化した状態であり、全硬化発熱量の６０〜１００％の発熱を終えた状態である。
【０１１１】
ゲル化の判定については、ＴＨＦ（テトラヒドロフラン）等の浸透性の大きい溶剤中に接着剤を浸し、２５℃で２０時間放置した後、接着剤が完全に溶解しないで膨潤した状態にあるものをゲル化したと判定した。なお、実験的には、以下のように判定した。
【０１１２】
ＴＨＦ中に接着剤（重量Ｗ１）を浸し、２５℃で２０時間放置した後、非溶解分を２００メッシュのナイロン布で濾過し、これを乾燥した後の重量を測定（重量Ｗ２）した。ＴＨＦ抽出率（％）をつぎの数式（２）のように算出した。ＴＨＦ抽出率が８０重量％を越えるものをゲル化していないとし、８０重量％以下のものをゲル化していると判定した。

【０１１３】
本発明では、フィラーを添加することにより、溶融粘度が大きくでき、さらにチクソトロピック性を発現できるために、上記効果をさらに大きくすることが可能となる。
【０１１４】
さらに、上記の効果に加えて、接着剤の放熱性向上、接着剤に難燃性の付与、接着時の温度において適正な粘度をもたせること、表面硬度の向上等の特性も付与できる。
（ 図面の簡単な説明）
図１（ａ）は本発明による単層の熱硬化性接着フィルムの断面図、図１（ｂ）は本発明による３層接着フィルムの断面図である。
【０１１５】
図２は、接着部材を有機配線基板に熱圧着した半導体搭載用基板の断面図である。
【０１１６】
図３は、接着部材を有機配線基板に熱圧着した半導体搭載用基板の断面図である。
【０１１７】
図４は、本発明の半導体装置の断面図である。
【０１１８】
図５は、本発明の半導体装置の他の例の断面図である。
【０１１９】
図６は、半導体搭載用基板および半導体装置の一実施例の製造工程を示す断面図である。
【０１２０】
図７は、半導体搭載用基板および半導体装置の他の実施例の製造工程を示す断面図である。
【０１２１】
図８は、本発明の半導体装置の他の例の断面図である。（ 発明を実施するための最良の形態）
以下、図面に基づき本発明の各種実施例について説明する。
＜実施例１＞
図１（ａ）は単層の熱硬化性接着フィルムの断面図であり、動的粘弾性装置で測定されるその硬化物の２５℃における弾性率が１０から２０００ＭＰａの範囲であり、かつ２６０℃における弾性率が３から５０ＭＰａの範囲で規定され、ＤＳＣ（示差熱量計）を用いて測定した場合の全硬化発熱量の１０〜４０％の発熱を終えた半硬化状態の熱硬化性接着剤１からなる。熱硬化性接着フイルム内に残存する溶媒量を２％以下に乾燥されたエポキシ基含有アクリル共重合体フィルムを用いた。
【０１２２】
図１（ｂ）は熱硬化性接着剤１をポリイミドフィルム２の両面に塗工された３層の接着フィルムの断面図を示す。この例ではポリイミドフィルムとして宇部興産製の５０μｍ厚のユーピレックス（商品名）を用いた。
【０１２３】
図２はワイヤボンディング方式で半導体端子部と配線基板側端子部とを接続するのに好適な、接着部材３を有機配線基板４に熱圧着した半導体搭載用基板の断面図、図３はＴＡＢのインナーボンディング方式で半導体端子部と配線板側端子部と接続するのに好適な、接着部材３をテープ状配線基板５に熱圧着した半導体搭載用基板の断面図である。図４は図２の半導体搭載用基板にチップ６をフェイスアップで接着し、半導体端子部と配線板側端子部とがワイヤ７によりワイヤボンディングされ、封止材で封止されてなる半導体装置の断面図、図５は図３の半導体搭載用基板にチップ６をフェイスダウンで接着したのちＴＡＢのインナーボンディング方式で半導体端子部と基板側端子部とが接続され、チップ６端面が液状封止材８で封止されてなる半導体装置の断面図である。なお、図８に示すように、配線９を基板の半導体チップ搭載側とは反対側に形成してもよい。この場合、外部接続端子１２は、半導体チップ搭載側とは反対の側に形成された配線９の表面に形成される。また、配線９の露出部分は、レジスト１１により覆われる。
【０１２４】
図６に半導体搭載用基板および半導体装置の製造工程を示す。
【０１２５】
動的粘弾性装置で測定されるその硬化物の２５℃における弾性率が１０から２０００ＭＰａの範囲であり、かつ２６０℃における弾性率が３から５０ＭＰａの範囲で規定され、ＤＳＣを用いて測定した場合の全硬化発熱量の１０〜４０％の発熱を終えた半硬化状態の熱硬化性接着剤１で構成される熱硬化性接着テープ（接着部材）３を所定の大きさに切断プレスで切断する（図６（ａ））。
【０１２６】
切断された熱硬化性接着テープ３を、１層のＣｕ配線が施され、外部はんだ端子用スルーホールが形成されたポリイミドフィルム基板（有機配線基板）４上面に精密に位置合わせした後、熱プレスにて熱圧着し半導体搭載用基板を得る（図６（ｂ））。
【０１２７】
この例では、熱硬化性接着フィルムの切断、およびポリイミドフィルム基板への精密位置決め搭載及び仮固定は個々に行い、その後、搭載した熱硬化性接着フィルムを一括して熱プレスにて本圧着して７連のフレーム状半導体搭載用基板を得た。さらにこの例では、熱硬化性接着フィルム３を切断する工程の前に、帯電した空気を吹き付けるエリミノスタット（静電気除去）工程を実施し、帯電した絶縁性のフィルムが切断工程時に治具に貼り付くことを防止した。また、さらに仮接着ならびに一括して本接着をする際の熱硬化性接着フィルム３に接触する熱プレスの上型にはテフロンないしはシリコンの離型表面処理を施し、熱硬化性フィルムが上型に粘着することを防止した。こうして得られた多連半導体搭載用フレーム基板に半導体チップ６をフェイスアップにて精密位置決め搭載し、熱プレスにて加圧し接着するチップマウント工程を経る。この例では半導体チップ側の加熱温度を少なくとも半導体搭載用基板側より高く設定し、両面から加熱・圧着した。
【０１２８】
その後、半導体チップ側の端子部と基板側端子部とを金線でワイヤボンディングするワイヤボンディング工程（図６（ｃ））、およびエポキシ系封止材にてトランスファーモールド成形して封止する封止工程（図６（ｄ））、そしてはんだボールを搭載しリフロー工程をへて外部端子９を形成するはんだボール形成工程をへて、本発明による半導体装置を得た（図６（ｅ））。封止材８として日立化成製ビフェニル系エポキシ封止材ＣＥＬ−９２００（商品名）を用いた。
＜比較例１＞
１層のＣｕ配線が施され、外部はんだ端子用スルーホールが形成されたポリイミドフィルム配線基板（実施例１１で使用したのと同じ）上面に、エポキシ樹脂を主成分とし、その硬化物のＤＭＡ（動的粘弾性測定装置）で測定される２５℃の弾性率が３０００ＭＰａの絶縁性液状接着剤をダイボンド装置にて滴下・塗布し、半導体チップを精密に位置決めし搭載した。その後、クリーンオーブン内で所定の硬化時間を経たのち、実施例１と同じワイヤボンディング工程、封止工程、及びはんだボール形成工程をへて半導体装置を得た。
＜比較例２＞
実施例１で使用したのと同じポリイミド配線基板に、シリコン樹脂を主成分としその硬化物の２５℃の弾性率が１０ＭＰａであり、かつ２６０℃における弾性率が測定不可能なほど小さい絶縁性液状接着剤、をダイボンド装置にて滴下・塗布し、半導体チップを搭載し、その後、実施例１と同じ工程をへて半導体装置を得た。
＜実施例２＞
図７に半導体搭載用基板および半導体装置の製造工程を示す。
【０１２９】
動的粘弾性装置で測定されるその硬化物の２５℃における弾性率が１０から２０００ＭＰａの範囲であり、かつ２６０℃における弾性率が３から５０ＭＰａの範囲で規定され、ＤＳＣを用いて測定した場合の全硬化発熱量の１０〜４０％の発熱を終えた半硬化状態の熱硬化性接着剤１で構成される熱硬化性接着テープ（接着部材）３を所定の大きさに切断プレスで切断する（図７（ａ））。
【０１３０】
切断された熱硬化性接着テープ３を、１層のＣｕ配線が施され、ＴＡＢテープ同様のインナーリード部と外部はんだ端子用のスルーホールが形成されたポリイミドフィルム基板５の上面に精密に位置合わせした後、熱プレスにて熱圧着して半導体搭載用基板を得た（図７（ｂ））。
【０１３１】
この例では、実施例１に記載された切断工程前の静電気除去工程、および熱プレス上型面への離型表面処理を施した同じ工程にて、多連半導体搭載用フレーム基板を得た。
【０１３２】
その後、半導体搭載用フレーム基板に半導体チップ６をフェイスダウンで精密位置合わせして順次搭載し、熱プレスにて熱圧着した（図７（ｃ））。その後、基板側端子であるＣｕインナーリード部１０を個々にＴＡＢインナーリードボンダー（この例ではシングルポイントボンダー）を用いて、チップ側の端子部に接続するインナーリードボンディングを経て（図７（ｄ））、チップ端面とポリイミドフィルム基板５の上面とをエポキシ系液状封止材８をディスペンスにて被覆し（図７（ｅ））、所定の加熱・硬化時間を経て、半導体装置を得た（図７（ｆ））。この例では、インナーリード部にはＣｕの上にＳｎめっきが施されたものを用い、半導体端子部にはＡｕめっきバンプが形成されているものを用いてＡｕ／Ｓｎ接合により接続した。
＜比較例３＞
１層のＣｕ配線が施され、ＴＡＢテープのインナーリード部と外部はんだ端子用のスルーホールが形成された実施例２と同じポリイミドフィルム基板の上面に、エポキシ樹脂を主成分とし、その硬化物のＤＭＡで測定される２５℃の弾性率が３０００ＭＰａの絶縁性液状接着剤をダイボンド装置にて滴下・塗布し、半導体チップを精密に位置決めし搭載した。しかし、樹脂がインナーボンディング部にまで流れ、その後のインナーボンディングができなかったが、そのまま実施例２と同様にチップ端面をエポキシ樹脂を主体とする液状封止材で封止し、はんだボールを形成した比較品を得た。
＜比較例４＞
１層のＣｕ配線が施され、ＴＡＢテープのインナーリード部と外部はんだ端子用のスルーホールが形成された実施例２と同じポリイミドフィルム基板の上面に、シリコン樹脂を主成分としその硬化物の２５℃の弾性率が１０ＭＰａであり、かつ２６０℃における弾性率が測定不可能なほど小さい絶縁性液状接着剤、をダイボンド装置にて滴下・塗布し、実施例２と同様に半導体チップを搭載した。しかし、樹脂がインナーボンディング部にまで流れ、その後のインナーボンディングができなかったが、そのまま実施例２と同様にチップ端面をエポキシ樹脂を主体とする液状封止材で封止し、はんだボールを形成した比較品を得た。
＜比較例５＞
シリコン樹脂を主成分としその硬化物の２５℃の弾性率が１０ＭＰａであり、かつ２６０℃における弾性率が測定不可能なほど小さい絶縁性液状接着剤をテフロン板に注型し、その後、所定の加熱温度・時間により硬化させて、低弾性のフィルムを得た。このフィルムの両面に比較例３に記載したエポキシ樹脂を主体とする熱硬化性接着剤を両面に塗布し、１層のＣｕ配線が施されＴＡＢテープのインナーリード部と外部はんだ端子用のスルーホールが形成された実施例２と同じポリイミドフィルム基板の上面に、熱プレスで熱圧着し、その後、半導体チップをフェイスダウンで接着した後、実施例２に記載したインナーリードボンディング工程、封止工程をへてはんだボールを形成した比較品を得た。
実施例１、実施例２、比較例１〜５の半導体装置のについて、耐吸湿リフロー試験を実施するとともに、ＦＲ−４配線基板にリフロー実装した各半導体装置について耐温度サイクル試験を実施した結果を表１に示す。吸湿リフロー試験については、吸湿前と８５℃８５％ＲＨの条件下で２４時間および４８時間吸湿させたのち最高温度２４０℃のＩＲリフローを実施した試験品中の剥離、クラックをＳＡＴ（超音波探査探傷装置）で調べた結果を表示した。また、各サンプルの耐温度サイクル試験は、基板実装後に−２５℃（３０分、ａｉｒ）〜１５０℃（３０分、ａｉｒ）の温度サイクルを実施したのち、パッケージ外部端子のはんだボールの接続抵抗を４端子法で測定し、５０ｍΩ以上になったものを不良とした。

【０１３３】
（注）
耐リフロー性
○：チップ６および有機配線基板４、５と熱硬化性接着剤３との界面に剥離およびボイドが極めて少なく、ＳＡＴ（超音波探査探傷装置）で検知できない。
△：熱硬化性接着剤３の塗布時に有機配線基板の配線間への埋め込みが充分でなくボイドが観察され、その箇所から剥離が進展しているものが、サンプル１０中２〜３。
×：上記した剥離がパッケージ外部にまで至り、リフロー後はパッケージに膨れ、クラックが観察されるもがサンプル１０中１０。剥離してワイヤーボンディング部やインナーリード部の断線にまで至るものが観察される。
耐温度サイクル性
○：はんだボール接続部の接続抵抗が変化しない。
×：はんだボール接続部の接続抵抗が５０ｍΩを越える端子が１つでも存在する。
−：インナーボンディングが出来ず、接続抵抗を測定できない。評価不可。
＜実施例３＞
エポキシ樹脂としてビスフェノールＡ型エポキシ樹脂（エポキシ当量２００、油化シェルエポキシ株式会社製のエピコート８２８を使用）４５重量部、クレゾールノボラック型エポキシ樹脂（エポキシ当量２２０、住友化学工業株式会社製のＥＳＣＮ００１を使用）１５重量部、エポキシ樹脂の硬化剤としてフェノールノボラック樹脂（大日本インキ化学工業株式会社製のプライオーフェンＬＦ２８８２を使用）４０重量部、エポキシ樹脂と相溶性がありかつ重量平均分子量が３万以上の高分子量樹脂としてフェノキシ樹脂（分子量５万、東都化成株式会社製のフェノトートＹＰ−５０を使用）１５重量部、エポキシ基含有アクリルゴムとしてエポキシ基含有アクリルゴム（分子量１００万、帝国化学産業株式会社製のＨＴＲ−８６０Ｐ−３を使用）１５０重量部、硬化促進剤として硬化促進剤１−シアノエチル−２−フェニルイミダゾール（キュアゾール２ＰＺ−ＣＮ）０．５重量部、シランカップリング剤としてγ−グリシドキシプロピルトリメトキシシラン（日本ユニカー株式会社製のＮＵＣ Ａ−１８７を使用）０．７重量部からなる組成物に、メチルエチルケトンを加えて撹拌混合し、真空脱気した。得られたワニスを、厚さ７５μｍの離型処理したポリエチレンテレフタレートフィルム上に塗布し、１４０℃で５分間加熱乾燥して、膜厚が８０μｍのＢステージ状態の塗膜を形成し接着フィルムを作製した。
【０１３４】
なおこの状態での接着剤の硬化度は、ＤＳＣ（デュポン社製９１２型ＤＳＣ）を用いて測定（昇温速度、１０℃／分）した結果、全硬化発熱量の１５％の発熱を終えた状態であった。また、ＴＨＦ中に接着剤（重量Ｗ１）を浸し、２５℃で２０時間放置した後、非溶解分を２００メッシュのナイロン布で濾過し、これを乾燥した後の重量を測定（重量Ｗ２）し、ＴＨＦ抽出率（＝（Ｗ１−Ｗ２）×１００／Ｗ１）を求めたところ、ＴＨＦ抽出率は３５重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置（レオロジ製、ＤＶＥ−Ｖ４）を用いて測定（サンプルサイズ 長さ２０ｍｍ、幅４ｍｍ、膜厚８０μｍ、昇温速度５℃／分、引張りモード 自動静荷重）した結果、２５℃で３６０ＭＰａ、２６０℃で４ＭＰａであった。
＜実施例４＞
実施例３で用いたフェノキシ樹脂を、カルボキシル基含有アクリロニトリルブタジエンゴム（分子量４０万、日本合成ゴム株式会社製のＰＮＲ−１を使用）に変更したほか、実施例１と同様にして接着フィルムを作製した。なお、この状態での接着剤の硬化度は、ＤＳＣを用いて測定した結果、全硬化発熱量の２０％の発熱を終えた状態であった。ＴＨＦ抽出率は、３５重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置を用いて測定した結果、２５℃で３００ＭＰａ、２６０℃で３ＭＰａであった。
＜実施例５＞
実施例３の接着剤ワニスの接着剤固形分１００体積部に対してシリカを１０体積部添加し、ビーズミルで６０分間混練したワニスを用いて実施例１と同様にして接着フィルムを作製した。ＤＳＣを用いて測定した結果、全硬化発熱量の１５％の発熱を終えた状態であった。ＴＨＦ抽出率は、３０重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置を用いて測定した結果、２５℃で１，５００ＭＰａ、２６０℃で１０ＭＰａであった。
＜実施例６＞
実施例３で用いたフェノキシ樹脂を用いないこと以外実施例１と同様にして接着フィルムを作製した。ＤＳＣを用いて測定した結果、全硬化発熱量の１５％の発熱を終えた状態であった。ＴＨＦ抽出率は、３５重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置を用いて測定した結果、２５℃で３５０ＭＰａ、２６０℃で４ＭＰａであった。
＜比較例６＞
実施例３のエポキシ基含有アクリルゴムの量を１５０重量部から５０重量部にしたこと以外は実施例１と同様にして接着フィルムを作製した。ＤＳＣを用いて測定した結果、全硬化発熱量の２０％の発熱を終えた状態であった。ＴＨＦ抽出率は、４０重量％であった。さらに、接着剤硬化物の貯蔵弾性率を、動的粘弾性測定装置を用いて測定した結果、２５℃で３，０００ＭＰａ、２６０℃で５ＭＰａであった。
＜比較例７＞
実施例３のエポキシ基含有アクリルゴムの量を１５０重量部から４００重量部にしたこと以外は実施例１と同様にして接着フィルムを作製した。ＤＳＣを用いて測定した結果、全硬化発熱量の２０％の発熱を終えた状態であった。ＴＨＦ抽出率は、３０重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置を用いて測定した結果、２５℃で２００ＭＰａ、２６０℃で１ＭＰａであった。
＜比較例８＞
実施例３のエポキシ基含有アクリルゴムの１５０重量部をフェノキシ樹脂に変更（フェノキシ樹脂１６０重量部）した他、実施例１と同様にして接着フィルムを作製した。この接着フィルムの全硬化発熱量は２０％であり、ＴＨＦ抽出率は、９０重量％であった。また、貯蔵弾性率は、２５℃で３，４００ＭＰａ、２６０℃で３ＭＰａであった。
＜比較例９＞
実施例３のエポキシ基含有アクリルゴムをアクリロニトリルブタジエンゴムに変更した他は、実施例１と同様にして接着フィルムを作製した。この接着フィルムの全硬化発熱量は、２０％、ＴＨＦ抽出率は、９０重量％であった。また、貯蔵弾性率は、２５℃で５００ＭＰａ、２６０℃で２ＭＰａであった。
得られた接着フィルムを用いて作製した半導体装置について、耐熱性、耐電食性、耐湿性を調べた。耐熱性の評価方法には、半導体チップと厚み２５μｍのポリイミドフィルムを基材に用いたフレキシブルプリント配線板を接着フィルムで貼り合せた半導体装置サンプル（片面にはんだボールを形成）の耐リフロークラック性と温度サイクル試験を適用した。耐リフロークラック性の評価は、サンプル表面の最高温度が２４０℃でこの温度を２０秒間保持するように温度設定したＩＲ（赤外線）リフロー炉にサンプルを通し、室温で放置することにより冷却する処理を２回繰り返したサンプル中のクラックの観察で行った。クラックの発生していないものを良好とし、発生していたものを不良とした。温度サイクル試験は、サンプルを−５５℃雰囲気に３０分間放置し、その後１２５℃の雰囲気に３０分間放置する工程を１サイクルとして、破壊が起きるまでのサイクル数を示した。また、耐電食性の評価は、ＦＲ−４基板にライン／スペース＝７５／７５μｍのくし形パターンを形成し、この上に接着フィルムを貼り合せたたサンプルを作製し、８５℃／８５％ＲＨ／ＤＣ６Ｖ印加の条件下で１，０００時間後の絶縁抵抗値を測定することにより行った。絶縁抵抗値が１０Ω以上を示したものを良好とし、１０Ω未満であったものを不良とした。また、耐湿性評価は、半導体装置サンプルをプレッシャークッカーテスター中で９６時間処理（ＰＣＴ処理）後接着フィルムの剥離及び変色を観察することにより行った。接着フィルムの剥離及び変色の認められなかったものを良好とし、剥離のあったもの又は変色のあったものを不良とした。その結果を表２に示す。

【０１３５】
実施例３、４及び５は、いずれも、エポキシ樹脂及びその硬化剤、エポキシ樹脂と相溶性の高分子量樹脂、エポキシ基含有アクリル系共重合体、硬化促進剤をともに含む接着剤であり、実施例６は、エポキシ樹脂及びその硬化剤、エポキシ基含有アクリル系共重合体、硬化促進剤をともに含む接着剤であり、本発明で規定した２５℃及び２６０℃での貯蔵弾性率を示している。これらは、耐リフロークラック性、温度サイクル試験、耐電食性、耐ＰＣＴ性が良好であった。
【０１３６】
比較例６は、本発明で規定したエポキシ基含有アクリル系共重合体の量が少ないため貯蔵弾性率が高く応力を緩和できずに耐リフロークラック性、温度サイクルテストでの結果が悪く信頼性に劣る。また、比較例７は、本発明で規定したエポキシ基含有アクリル系共重合体の量が多すぎるため貯蔵弾性率が低く良好であるが、接着フィルムの取扱性が悪い。比較例８は、本発明で規定したエポキシ基含有アクリル系共重合体を含まない組成であるため貯蔵弾性率が高く比較例１と同様、応力を緩和できずに耐リフロークラック性、温度サイクルテストでの結果が悪い。比較例９は、本発明で規定したエポキシ基含有アクリル系共重合体を含まず、それ以外のゴム成分を含み２５℃での貯蔵弾性率が低いが耐電食性に劣る結果を示した。
＜実施例７＞
エポキシ樹脂としてビスフェノールＡ型エポキシ樹脂（エポキシ当量２００、油化シェルエポキシ株式会社製商品名のエピコート８２８を使用）４５重量部、クレゾールノボラック型エポキシ樹脂（エポキシ当量２２０、住友化学工業株式会社製商品名のＥＳＣＮ００１を使用）１５重量部、エポキシ樹脂の硬化剤としてフェノールノボラック樹脂（大日本インキ化学工業株式会社製商品名のプライオーフェンＬＦ２８８２を使用）４０重量部、エポキシ樹脂と相溶性がありかつ重量平均分子量が３万以上の高分子量樹脂としてフェノキシ樹脂（分子量５万、東都化成株式会社製商品名のフェノトートＹＰ−５０を使用）１５重量部、エポキシ基含有アクリル系共重合体としてエポキシ基含有アクリルゴム（分子量１００万、帝国化学産業株式会社製商品名のＨＴＲ−８６０Ｐ−３を使用）１５０重量部、硬化促進剤として硬化促進剤１−シアノエチル−２−フェニルイミダゾール（キュアゾール２ＰＺ−ＣＮ）０．５重量部、シランカップリング剤としてγ−グリシドキシプロピルトリメトキシシラン（日本ユニカー株式会社製商品名のＮＵＣ Ａ−１８７を使用）０．７重量部からなる組成物に、メチルエチルケトンを加えて攪拌混合し、真空脱気した。得られたワニスを、厚さ５０μｍのプラズマ処理を施したポリイミドフィルム上に塗布し、１３０℃で５分間加熱乾燥して、膜厚が５０μｍのＢステージ状態の塗膜を形成し片面接着フィルムを作製した。つぎに、この片面接着フィルムのポリイミドフィルムの接着剤を塗布していない面に同じワニスを塗布し、１４０℃で５分間加熱乾燥して、膜厚が５０μｍのＢステージ状態の塗膜を形成し三層構造の両面接着フィルムを作製した。
【０１３７】
なおこの状態での接着フィルムの接着剤成分の硬化度は、ＤＳＣ（デュポン社製商品名９１２型ＤＳＣ）を用いて測定（昇温速度、１０℃／分）した結果、全硬化発熱量の１５％の発熱を終えた状態であった。また、ＴＨＦ中に接着剤（重量Ｗ１）を浸し、２５℃で２０時間放置した後、非溶解分を２００メッシュのナイロン布で濾過し、これを乾燥した後の重量を測定（重量Ｗ２）し、ＴＨＦ抽出率（＝（Ｗ１−Ｗ２）×１００／Ｗ１）を求めたところ、ＴＨＦ抽出率は３５重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置を用いて測定した結果、２５℃で３６０ＭＰａ、２６０℃で４ＭＰａであった。
＜実施例８＞
実施例７で用いたフェノキシ樹脂を、カルボキシル基含有アクリロニトリルブタジエンゴム（分子量４０万、日本合成ゴム株式会社製商品名のＰＮＲ−１を使用）に変更したほか、実施例１と同様にして三層構造の両面接着フィルムを作製した。なお、この状態での接着フィルムの接着剤成分の硬化度は、ＤＳＣを用いて測定した結果、全硬化発熱量の２０％の発熱を終えた状態であった。ＴＨＦ抽出率は、３５重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置を用いて測定した結果、２５℃で３００ＭＰａ、２６０℃で３ＭＰａであった。
＜実施例９＞
実施例７で用いた接着剤ワニスを厚さ５０μｍのポリエチレンテレフタレートフィルム上に塗布し、１４０℃で５分間加熱乾燥して、膜厚が５０μｍのＢステージ状態の塗膜を形成し、コア材となる耐熱性熱可塑性フィルムに貼り合わせるための接着フィルムを作製した。この接着フィルムを厚さ５０μｍのプラズマ処理を施したポリイミドフィルムの両面に真空ラミネータを用いて、ラミネータロール温度８０℃、送り速度０．２ｍ／分、線圧５ｋｇのラミネート条件で貼り合わせることにより三層構造の両面接着フィルムを作製した。なお、この状態での接着フィルムの接着剤成分の硬化度は、ＤＳＣを用いて測定した結果全硬化発熱量の２０％の発熱を終えた状態であった。ＴＨＦ抽出率は、３５重量％であった。さらに、接着剤硬化物の貯蔵弾性率を動的粘弾性測定装置を用いて測定した結果、２５℃で３６０ＭＰａ、２６０℃で４ＭＰａであった。
＜比較例１０＞
実施例７で用いた接着剤ワニスを厚さ５０μｍのポリエチレンテレフタレートフィルム上に塗布し、１４０℃で５分間加熱乾燥して、膜厚が７５μｍのＢステージ状態の塗膜を形成して接着フィルムを作製した。この接着フィルムを２枚用い、実施例３と同様のラミネート条件で貼り合わせて、コア材を用いない接着フィルムを作製した。得られた接着フィルムの接着剤成分の全硬化発熱量は２０％であり、ＴＨＦ抽出率は３５重量％であった。また、貯蔵弾性率は、２５℃で３６０ＭＰａ、２６０℃で４ＭＰａであった。
＜比較例１１＞
実施例７のコア材となる耐熱性熱可塑性フィルムとして用いたポリイミドフィルムをポリプロピレンフィルムに変更した他は、実施例１と同様にして三層構造の両面接着フィルムを作製した。この接着フィルムの接着剤成分の全硬化発熱量は、２０％、ＴＨＦ抽出率は、３５重量％であった。また、貯蔵弾性率は、２５℃で３６０ＭＰａ、２６０℃で４ＭＰａであった。
＜比較例１２＞
実施例７のエポキシ基含有アクリル系共重合体をフェノキシ樹脂に変更した他（フェノキシ樹脂１６５重量部）、実施例１と同様にして三層構造の両面接着フィルムを作製した。この接着フィルムの接着剤成分の全硬化発熱量は２０％であり、ＴＨＦ抽出率は、９０重量％であった。また、貯蔵弾性率は、２５℃で３，４００ＭＰａ、２６０℃で３ＭＰａであった。
＜比較例１３＞
実施例７のエポキシ基含有アクリル系共重合体をアクリロニトリルブタジエンゴムに変更した他は、実施例１と同様にして三層構造の両面接着フィルムを作製した。この接着フィルム接着剤成分の全硬化発熱量は、２０％、ＴＨＦ抽出率は、９０重量％であった。また、貯蔵弾性率は、２５℃で５００ＭＰａ、２６０℃で２ＭＰａであった。
【０１３８】
得られた接着フィルムについて、耐熱性、耐電食性、耐湿性を調べた。耐熱性の評価方法には、半導体チップとプリント配線板を三層構造の両面接着フィルムで貼り合せたサンプルの耐リフロークラック性と温度サイクル試験を適用した。耐リフロークラック性の評価は、サンプル表面の最高温度が２４０℃でこの温度を２０秒間保持するように温度設定したＩＲリフロー炉にサンプルを通し、室温で放置することにより冷却する処理を２回繰り返したサンプル中のクラックの観察で行った。クラックの発生していないものを良好とし、発生していたものを不良とした。温度サイクル試験は、サンプルを−５５℃雰囲気に３０分間放置し、その後１２５℃の雰囲気に３０分間放置する工程を１サイクルとして、破壊が起きるまでのサイクル数を示した。また、耐電食性の評価は、ＦＲ−４基板にライン／スペース＝７５／７５μｍのくし形パターンを形成し、この上に接着フィルムを貼り合せたサンプルを作製し、８５℃／８５％ＲＨ／ＤＣ６Ｖ印加の条件下で１，０００時間後の絶縁抵抗値を測定することにより行った。絶縁抵抗値が１０Ω以上を示したものを良好とし、１０Ω未満であったものを不良とした。また、耐湿性評価は、耐熱性評価サンプルをプレッシャークッカーテスター中で９６時間処理（ＰＣＴ処理）後接着フィルムの剥離及び変色を観察することにより行った。接着フィルムの剥離及び変色の認められなかったものを良好とし、剥離のあったもの又は変色のあったものを不良とした。その結果を表３に示す。

【０１３９】
実施例７、８、９は、何れも、コア材に耐熱性熱可塑性フィルムを用いた三層構造の両面接着フィルムであり、接着剤成分にエポキシ樹脂及びその硬化剤、エポキシ樹脂と相溶性の高分子量樹脂、エポキシ基含有アクリル系共重合体をともに含ため、本発明で規定した２５℃及び２６０℃での貯蔵弾性率を示している。これらは、取り扱い性に優れ、耐リフロークラック性、温度サイクル試験、耐電食性、耐ＰＣＴ性が良好であった。
【０１４０】
比較例１０は、本発明で規定したコア材に耐熱性熱可塑性フィルムを用いた三層構造の両面接着フィルムではないため、取り扱い性に劣っていた。比較例１１は、コア材に耐熱性に劣るポリプロピレンフィルムを用いたため、耐リフロー性及び温度サイクル試験結果に劣っていた。比較例１２は、本発明で規定したエポキシ基含有アクリル系共重合体を含まない組成であったために、規定した２５℃での貯蔵弾性率を超えた高い値を示しており、耐リフロークラック性及び温度サイクル試験結果に劣っていた。比較例１３は、本発明で規定したエポキシ基含有アクリルゴムを含まずに規定した２５℃での貯蔵弾性率に合わせていたために、耐電食性や耐ＰＣＴ性に劣る結果を示した。
（産業上の利用可能性）
本発明により、耐吸湿リフロー性に優れ、かつマザーボードに実装した状態での耐温度サイクル性に優れる半導体パッケージを製造することができる。
【０１４１】
本発明の接着剤及び接着フィルムは、室温付近での弾性率が低いために、ガラスエポキシ基板やポリイミド基板に代表されるリジッドプリント配線板及びフレキシブルプリント配線板に半導体チップを実装した場合の熱膨張係数の差がもとで起きる加熱冷却時の熱応力を緩和させることができる。そのため、リフロー時のクラックの発生が認められず、耐熱性に優れている。また、エポキシ基含有アクリル系共重合体を低弾性率成分として含んでおり、耐電食性、耐湿性、特にＰＣＴ処理等厳しい条件下で耐湿試験を行なった場合の劣化が少なく優れた特徴を有する接着材料を提供することができる。
【０１４２】
本発明のコア材に耐熱性熱可塑性フィルムを用いた三層構造の両面接着フィルムは、接着剤層の室温付近での弾性率が低いにもかかわらず、取扱性に優れ、しかも、ガラスエポキシ基板やポリイミド基板に代表されるリジッドプリント配線板及びフレキシブルプリント配線板に半導体チップを実装した場合の熱膨張係数の差がもとで起きる加熱冷却時の熱応力を緩和させることができる。そのため、リフロー時のクラックの発生が認められず、耐熱性に優れている。また、エポキシ基含有アクリル系共重合体を低弾性率成分として含んでおり、耐電食性、耐湿性、特にＰＣＴ処理等厳しい条件下で耐湿試験を行なった場合の劣化が少なく優れた特徴を有する接着材料を提供することができる。
【０１４３】
本発明の、外部端子が基板裏面にエリアアレイ状に配列された半導体パッケージは特に携帯機器やＰＤＡ用途の小型電子機器に搭載されるのに好適である。
【図面の簡単な説明】
【図１】図１（ａ）は本発明による単層の熱硬化性接着フィルムの断面図、図１（ｂ）は本発明による３層接着フィルムの断面図である。
【図２】図２は、接着部材を有機配線基板に熱圧着した半導体搭載用基板の断面図である。
【図３】図３は、接着部材を有機配線基板に熱圧着した半導体搭載用基板の断面図である。
【図４】図４は、本発明の半導体装置の断面図である。
【図５】図５は、本発明の半導体装置の他の例の断面図である。
【図６】図６は、半導体搭載用基板および半導体装置の一実施例の製造工程を示す断面図である。
【図７】図７は、半導体搭載用基板および半導体装置の他の実施例の製造工程を示す断面図である。
【図８】図８は、本発明の半導体装置の他の例の断面図である。[0001]
(Technical field)
The present invention relates to a semiconductor device, a manufacturing method thereof, a semiconductor chip mounting substrate suitably used for manufacturing the semiconductor device, a manufacturing method thereof, an adhesive, and a double-sided adhesive film.
[0002]
(Background technology)
In recent years, along with the trend toward downsizing and high frequency operation of electronic devices, it is required that the semiconductor package to be mounted on the substrate be mounted at a high density on the substrate. Development of small packages called micro BGA (ball grid array) and CSP (chip size package) arranged in an area array is in progress.
[0003]
In these packages, a chip is mounted on an organic substrate such as a glass epoxy substrate having a two-layer wiring structure or a polyimide substrate having a one-layer wiring structure via an insulating adhesive, and a chip-side terminal and a wiring board-side terminal Are connected by wire bonding or TAB (tape automated bonding) inner bonding method, and the connection portion and the upper surface portion or end surface portion of the chip are sealed with an epoxy type sealing material or an epoxy type liquid sealing material. A structure is adopted in which metal terminals such as solder balls are arranged in an area array on the back surface. A method of mounting a plurality of these packages on a substrate of an electronic device at a high density by a solder reflow method is being adopted.
[0004]
However, as an example of the insulating adhesive used in these packages, a liquid epoxy die bond material having a storage elastic modulus at 25 ° C. measured by a dynamic viscoelasticity device of 3000 MPa or more is used. The solder ball connection portion (secondary side) after the mounting on the substrate was poor in connection reliability and inferior in temperature cycle resistance.
[0005]
Furthermore, in other cases, a liquid silicon elastomer having a storage elastic modulus at 25 ° C. of 10 MPa or less has been proposed as an insulating adhesive, and although it has excellent temperature cycle resistance, it has a high temperature with respect to the surface of the wiring board. There was a problem that the adhesiveness at the time was poor and the moisture absorption reflow resistance was poor.
[0006]
In particular, with regard to reflow resistance, in both cases, it is easy to entrain voids in the process of applying a liquid insulating adhesive to an organic substrate, and the void starts as a starting point, and cracks develop during moisture absorption reflow. A failure mode in which the bulges were observed was observed.
[0007]
In addition, with the development of electronic equipment, the mounting density of electronic components has increased, and semiconductor bare chip mounting on printed wiring boards, which can be expected to be low in cost, has been promoted.
[0008]
A ceramic substrate such as alumina has been often used as a substrate for mounting a semiconductor chip. This is because the thermal expansion coefficient of the semiconductor chip is as small as about 4 ppm / ° C., so that a mounting substrate having a relatively low thermal expansion coefficient is required to ensure connection reliability, and the semiconductor chip is generated. The main reason was that it was required to use a mounting substrate having a relatively high thermal conductivity in order to make it easier to dissipate the heat to the outside. A liquid adhesive typified by silver paste is used for mounting a semiconductor chip on such a ceramic substrate.
[0009]
Further, film adhesives are used in flexible printed wiring boards and the like, and a system mainly composed of acrylonitrile butadiene rubber is used.
[0010]
In the study as a printed wiring board-related material, an adhesive containing an acrylic resin, an epoxy resin, a polyisocyanate, and an inorganic filler disclosed in Japanese Patent Application Laid-Open No. 60-243180 is disclosed as an improvement in solder heat resistance after moisture absorption. In addition, there are acrylic resins and epoxy resins disclosed in JP-A-61-138680, and adhesives containing a primary amine compound and an inorganic filler at both ends having urethane bonds in the molecule. (Pressure cooker test) When the moisture resistance test was conducted under severe conditions such as processing, the deterioration was large and insufficient.
[0011]
When silver paste adhesive is used for mounting semiconductor chips on ceramic substrates, the dispersion of silver filler is not uniform due to sedimentation of the silver filler, and it is necessary to pay attention to the storage stability of the paste. There are problems such as inferiority to LOC (lead on chip) and the like.
[0012]
In addition, film adhesives often use acrylonitrile butadiene rubber as the main component, but have disadvantages such as a large decrease in adhesive strength after long-time treatment at high temperatures and poor corrosion resistance. was there. In particular, when the moisture resistance test was performed under severe conditions such as PCT processing used for reliability evaluation of semiconductor-related parts, the deterioration was large.
[0013]
In the ones disclosed in JP-A-60-243180 and JP-A-61-138680, when a moisture resistance test was performed under severe conditions such as PCT treatment, the deterioration was large and insufficient. .
[0014]
When mounting a semiconductor chip on a printed wiring board using an adhesive as a material related to these printed wiring boards, the difference in the thermal expansion coefficient between the semiconductor chip and the printed wiring board is large and cracks can occur during reflow. There wasn't. Moreover, when the moisture resistance test under severe conditions such as a temperature cycle test and PCT treatment was performed, the deterioration was so great that it could not be used.
(Disclosure of the Invention)
The present invention has heat resistance, electric corrosion resistance, and moisture resistance necessary for mounting a semiconductor chip having a large difference in thermal expansion coefficient on a printed wiring board such as a glass epoxy substrate or a flexible substrate. The present invention provides an adhesive, an adhesive film, and a semiconductor device in which a semiconductor chip and a wiring board are bonded using the adhesive film, which reduces deterioration when a moisture resistance test is performed under severe conditions.
[0015]
Further, the present invention is a semiconductor device in which a semiconductor chip is mounted on an organic support substrate via an adhesive, and external terminals are arranged in an area array on the back surface of the substrate. The present invention provides a semiconductor device that improves moisture absorption reflow resistance, a manufacturing method thereof, a semiconductor chip mounting substrate suitably used for manufacturing the semiconductor device, a manufacturing method thereof, an adhesive, and a double-sided adhesive film.
[0016]
The semiconductor device of the present invention is a semiconductor device in which a semiconductor chip is mounted on an organic support substrate via an adhesive member, and a predetermined wiring is formed on the side of the organic support substrate on which the semiconductor chip is mounted. An external connection terminal is formed in an area array on the side of the organic support substrate opposite to the side on which the semiconductor chip is mounted, and the predetermined wiring includes a semiconductor chip terminal and the external connection terminal. Connected, at least a connection portion between the semiconductor chip terminal and the predetermined wiring is resin-sealed, and the adhesive member includes an adhesive layer, which is measured by the dynamic viscoelasticity measuring device for the adhesive The storage elastic modulus at 25 ° C. is 10 to 2000 MPa and the storage elastic modulus at 260 ° C. is 3 to 50 MPa.
[0017]
The semiconductor chip mounting substrate of the present invention is a semiconductor chip mounting substrate of an organic substrate on which a semiconductor chip is mounted via an adhesive member, and the semiconductor chip mounting side of the organic substrate and the semiconductor chip A predetermined wiring is formed on at least one side opposite to the side on which the semiconductor chip is mounted, and external connection terminals are arranged in an area array on the side opposite to the side on which the semiconductor chip of the organic substrate is mounted. The adhesive member is provided with an adhesive layer, and the storage elastic modulus at 25 ° C. measured by the dynamic viscoelasticity measuring device of the adhesive cured product is 10 to 2000 MPa and stored at 260 ° C. The elastic modulus is 3 to 50 MPa, and the adhesive member has a predetermined size and is formed at a predetermined location on the organic substrate.
[0018]
According to the method for manufacturing a semiconductor chip mounting substrate of the present invention, a predetermined wiring is formed on at least one of the side on which the semiconductor chip is mounted and the side on which the semiconductor chip is mounted, and the semiconductor chip is mounted. On the opposite side to the side where the external connection terminals are formed, an organic substrate having external connection terminals formed in an area array shape has a storage elastic modulus at 25 ° C. of 10 to 2000 MPa and 260 of the cured product measured with a dynamic viscoelasticity measuring device. An adhesive member having an adhesive layer having a storage elastic modulus at 3 ° C. of 3 to 50 MPa, and the adhesive has a heat generation of 10 to 40% of the total curing heat value when measured using a DSC (differential calorimeter). The adhesive member film that is in a semi-cured state is cut into a predetermined size and thermocompression-bonded onto the organic substrate.
[0019]
According to the method of manufacturing a semiconductor device of the present invention, a predetermined wiring is formed on at least one of the side on which the semiconductor chip is mounted and the side on which the semiconductor chip is mounted, and the side on which the semiconductor chip is mounted. On the opposite side, a semiconductor mounting substrate of an organic substrate in which external connection terminals are formed in an area array form has a storage elastic modulus at 25 ° C. of 10 to 2000 MPa of a cured product measured with a dynamic viscoelasticity measuring device. A step of bonding an adhesive member having an adhesive layer having a storage elastic modulus at 260 ° C. of 3 to 50 MPa, a step of mounting a semiconductor chip via the adhesive member, the predetermined wiring for a semiconductor chip terminal and the external connection It is characterized by comprising a step of connecting to a terminal, and a step of resin-sealing at least a connection portion between the semiconductor chip terminal and a predetermined wiring.
[0020]
The adhesive of the present invention has the following compositions A to D.
A. (1) Tg (glass transition temperature) containing 2 to 6% by weight of glycidyl (meth) acrylate is −10 ° C. or more and weight average molecular weight is 800,000 or more with respect to 100 parts by weight of the epoxy resin and its curing agent. An adhesive comprising 100 to 300 parts by weight of an epoxy group-containing acrylic copolymer and (3) 0.1 to 5 parts by weight of a curing accelerator.
B. (1) To 100 parts by weight of the epoxy resin and its curing agent, (2) 10 to 40 parts by weight of a high molecular weight resin having compatibility with the epoxy resin and having a weight average molecular weight of 30,000 or more, (3) glycidyl (meth) 100 to 300 parts by weight of an epoxy group-containing acrylic copolymer having a Tg (glass transition temperature) containing acrylate of 2 to 6% by weight and a weight average molecular weight of 800,000 or more, and (4) a curing accelerator. An adhesive containing 0.1 to 5 parts by weight.
C. (1) An epoxy group-containing acrylic having a Tg of -10 ° C. or more and a weight average molecular weight of 800,000 or more with respect to 100 parts by weight of an epoxy resin and a phenol resin (2) glycidyl (meth) acrylate An adhesive comprising 100 to 300 parts by weight of a copolymer and (3) 0.1 to 5 parts by weight of a curing accelerator.
D. (1) Tg containing 10 to 40 parts by weight of phenoxy resin and (3) 2 to 6% by weight of glycidyl (meth) acrylate is −10 ° C. or more and weight average with respect to 100 parts by weight of epoxy resin and phenol resin An adhesive comprising 100 to 300 parts by weight of an epoxy group-containing acrylic copolymer having a molecular weight of 800,000 or more and (4) 0.1 to 5 parts by weight of a curing accelerator.
[0021]
The double-sided adhesive film of the present invention has the following three-layer structure E to H.
E. Using a heat-resistant thermoplastic film as a core material, (2) Tg (glass) containing 2 to 6% by weight of glycidyl (meth) acrylate with respect to 100 parts by weight of the epoxy resin and its curing agent on both sides of the core material Adhesive containing 100 to 300 parts by weight of an epoxy group-containing acrylic copolymer having a transition temperature) of −10 ° C. or more and a weight average molecular weight of 800,000 or more and (3) 0.1 to 5 parts by weight of a curing accelerator A double-sided adhesive film having a three-layer structure.
F. A heat-resistant thermoplastic film is used as the core material, and (2) the epoxy resin and 100 parts by weight of the curing agent are both on the both sides of the core material, and (2) the epoxy resin is compatible and the weight average molecular weight is 30,000 or more. Epoxy group containing 10 to 40 parts by weight of a high molecular weight resin, (3) Tg (glass transition temperature) containing 2 to 6% by weight of glycidyl (meth) acrylate is -10 ° C. or more and the weight average molecular weight is 800,000 or more A double-sided adhesive film having a three-layer structure having an adhesive containing 100 to 300 parts by weight of an acrylic copolymer and (4) 0.1 to 5 parts by weight of a curing accelerator.
G. A heat-resistant thermoplastic film is used as a core material, and (2) Tg containing 2 to 6% by weight of glycidyl (meth) acrylate is -10 with respect to 100 parts by weight of epoxy resin and phenol resin on both sides of the core material. A three-layer structure having an adhesive containing 100 to 300 parts by weight of an epoxy group-containing acrylic copolymer having a weight average molecular weight of 800,000 or more and (3) 0.1 to 5 parts by weight of a curing accelerator. Double-sided adhesive film.
H. A heat-resistant thermoplastic film is used as a core material, and (2) 10 to 40 parts by weight of a phenoxy resin and (3) glycidyl (meth) acrylate on both sides of the core material with respect to 100 parts by weight of an epoxy resin and a phenol resin. 100 to 300 parts by weight of an epoxy group-containing acrylic copolymer having a Tg of 2 to 6% by weight of −10 ° C. or more and a weight average molecular weight of 800,000 or more, and (4) 0.1 to 5% by weight of a curing accelerator. A double-sided adhesive film having a three-layer structure having an adhesive including a part.
[0022]
In the semiconductor device of the present invention, the predetermined wiring can be directly connected to the semiconductor chip terminal by wire bonding or TAB (tape automated bonding) inner bonding method.
[0023]
In the semiconductor device of the present invention, the adhesive member is preferably in the form of a film, and the adhesive member includes an adhesive layer. As the resin component of the adhesive, an epoxy resin, an epoxy group-containing acrylic copolymer, an epoxy resin cured Those containing an agent and an epoxy resin curing accelerator are used.
[0024]
The adhesive member uses a heat-resistant thermoplastic film with a glass transition temperature of 200 ° C or higher, such as polyimide, polyethersulfone, polyamideimide or polyetherimide film, as the core material, and an adhesive layer is formed on both sides of the core material The structure of the structure is preferable. A liquid crystal polymer film is also used as the heat resistant thermoplastic film. The amount of residual solvent in the adhesive layer is preferably 5% by weight or less.
[0025]
In the semiconductor chip mounting substrate of the present invention, the adhesive member is preferably in the form of a film, and the adhesive member includes an adhesive layer. The resin component of the adhesive includes an epoxy resin and an epoxy group-containing acrylic copolymer. Those containing a polymer, an epoxy resin curing agent and an epoxy resin curing accelerator are used.
[0026]
The adhesive member uses a heat-resistant thermoplastic film with a glass transition temperature of 200 ° C or higher, such as polyimide, polyethersulfone, polyamideimide or polyetherimide film, as the core material, and an adhesive layer is formed on both sides of the core material The structure of the structure is preferable. A liquid crystal polymer film is also used as the heat resistant thermoplastic film. The amount of residual solvent in the adhesive layer is preferably 5% by weight or less.
[0027]
The adhesive member formed at a predetermined location on the organic substrate is a film punched to a predetermined size with a punching die, and the adhesive member formed at a predetermined location on the organic substrate is The adhesive of the adhesive member is a film in a semi-cured state in which the heat generation of 10 to 40% of the total curing heat generation amount measured using DSC is finished, and after being cut into a predetermined size, on the organic substrate It is thermocompression bonded to.
[0028]
In the method for manufacturing a semiconductor chip mounting substrate according to the present invention, the cut adhesive member films are individually precisely positioned and then temporarily bonded by a hot press, and a plurality of adhesive member films are placed on multiple organic substrates. After that, it can be pressed and bonded together by a heated mold release surface treatment mold. The surface release material of the release surface treatment mold is preferably at least one of Teflon and silicone. At least one eliminostat process for removing static electricity generated during conveyance of the adhesive member film can be added before the adhesive member film cutting process.
[0029]
In the method for manufacturing a semiconductor device of the present invention, heating can be performed from both the lower surface side of the semiconductor mounting substrate and the semiconductor chip side, and at least the temperature on the chip side can be increased.
[0030]
In the adhesive of the present invention, it is preferable to use after the completion of heat generation of 10 to 40% of the total calorific value when measured using DSC, and measured using a dynamic viscoelasticity measuring device. The storage elastic modulus of the cured adhesive is preferably 10 to 2000 MPa at 25 ° C. and 3 to 50 MPa at 260 ° C.
[0031]
The inorganic filler is used in an amount of 2 to 20 parts by volume with respect to 100 parts by volume of the adhesive resin component, and the inorganic filler is preferably alumina or silica.
[0032]
An adhesive is formed on the base film to form an adhesive film, and the semiconductor device can be obtained by bonding the semiconductor chip and the wiring board using the adhesive film.
[0033]
In the double-sided adhesive film of the present invention, the adhesive is preferably used in a state in which heat generation of 10 to 40% of the total curing heat generation amount measured using DSC is completed. It is preferable that the storage elastic modulus of the cured adhesive is 10 to 2000 MPa at 25 ° C and 3 to 50 MPa at 260 ° C. The inorganic filler is used in an amount of 2 to 20 parts by volume with respect to 100 parts by volume of the adhesive resin component, and the inorganic filler is preferably alumina or silica.
[0034]
The heat-resistant thermoplastic film used for the core material preferably has a glass transition temperature of 200 ° C. or higher. Examples of such a heat-resistant thermoplastic film having a glass transition temperature of 200 ° C. or higher include polyimide, polyethersulfone, polyamideimide, and poly Ether imide films are preferred. A liquid crystal polymer film is also used as a heat-resistant thermoplastic film used for the core material.
[0035]
In order to solve the problems described in the prior art, first, a semiconductor chip is mounted on an organic wiring board via an insulating adhesive, and the chip-side terminal and the wiring board-side terminal are connected by gold wire bonding, and soldering is performed. Using a FEM elasto-plastic analysis method, the relationship between the physical properties of the insulating adhesive used for the semiconductor package in which the ball external terminals are arranged in an area array on the back of the substrate and the temperature cycle resistance after mounting the motherboard was investigated. .
[0036]
As a result, the stress applied to the external terminals of the board solder balls resulting from the difference between the CTE of the chip (linear thermal expansion coefficient: 3.5 ppm) and the CTE of the motherboard (14-18 ppm) reduces the elastic modulus E of the insulating adhesive. If the elastic modulus E is 2000 MPa or less, preferably 1000 MPa or less, as measured by a dynamic viscoelasticity measuring device, the equivalent distortion of the solder terminal at the outer periphery is sufficiently small and is applied to the Coffin-Manson rule. However, it was found that there was a fatigue life of 1000 cycles or more at a temperature cycle of -55 ° C to 125 ° C.
[0037]
On the contrary, the elastic modulus E of a normal epoxy die bonding material is 3000 MPa or more, and it has been found that there is a problem with the temperature cycle reliability of solder balls.
[0038]
On the other hand, when the elastic modulus E of the insulating adhesive is lowered to 10 MPa or less, which is about the level of silicon elastomer, the elastic modulus E decreases as the reflow temperature reaches an upper limit of 260 ° C., exceeding the measurement limit, and the function as a strength member is lost. As a result, it is impossible to expect adhesion and retention between the substrate surface and the silicon chip. The temperature dependency of the shear bond strength has the same tendency as the temperature dependency of the elastic modulus, and becomes smaller as the temperature increases. In other words, unless the elastic modulus E at a reflow temperature of 260 ° C. is at least 3 MPa, shear adhesive strength cannot be expected. If delamination occurs at the interface with the chip or substrate at a reflow temperature of 260 ° C., it leads to a failure of the gold wire in the subsequent temperature resistance cycle test and a failure of the corrosion disconnection in the moisture resistance test.
[0039]
Therefore, the elastic modulus at normal temperature of the insulating adhesive (adhesive cured product) for mounting the chip on the organic wiring substrate is in the range of 10 to 2000 MPa, desirably 50 to 1500 MPa, most desirably 100 to 1000 MPa. It was found that the use of an elastic modulus at a reflow temperature of 260 ° C. in the range of 3 to 50 MPa is a condition for satisfying temperature cycle resistance and moisture absorption reflow resistance.
[0040]
As a result of searching for various thermosetting resins having the temperature dependence of the above elastic modulus, it was found that the epoxy group-containing acrylic copolymer is a suitable adhesive capable of realizing the physical properties in the range.
[0041]
Furthermore, there is a void generated at the interface between the organic wiring board and the insulating adhesive as a factor that deteriorates moisture absorption reflow resistance. In a normal method in which a small amount of a liquid thermosetting adhesive is dropped and applied, voids are likely to be caught, causing cracks and substrate swelling during moisture reflow.
[0042]
Therefore, the above-mentioned epoxy-containing acrylic copolymer is processed into a film, and the residual solvent amount is 5% or less, preferably 2% or less, and the total curing when measured using a DSC (differential calorimeter). An adhesive film having a B-stage cured state of 10 to 40% of the calorific value is cut into a predetermined size and pasted on an organic wiring board by a hot press to obtain a semiconductor mounting board.
[0043]
After that, the chip is mounted and thermocompression bonded, and a packaged product is obtained through a wire bonding process and a sealing process.
[0044]
The package thus obtained is less prone to gaps and voids at the interface between the chip and the substrate, but it is better to heat not only the semiconductor mounting substrate side but also the chip side when heating the chip. It has been found that a gap is hardly generated at the interface with the adhesive, the resin is sufficiently embedded between the wiring portions of the substrate, and the moisture absorption reflow resistance is improved. Furthermore, it has been found that if the residual solvent amount of the adhesive film is controlled to 5% or less, preferably 2% or less, bubbles are not generated during the curing process of the adhesive film and the moisture absorption reflow resistance is not lowered. It was.
[0045]
The application of the adhesive film having the physical properties described above is not limited to the semiconductor package in which the chip-side terminal and the wiring board-side terminal are connected by gold wire bonding and the external terminals are arranged in an area array on the back surface of the substrate. The same operation and effect can be obtained for a package in which the terminal and the wiring board side terminal are connected by a TAB (tape automated bonding) inner bonding method (a package in which the chip side terminal and the wiring board side terminal are directly connected). In addition, the temperature cycle resistance and moisture absorption reflow resistance of all area array packages having a structure in which a semiconductor chip is bonded to an organic wiring substrate through an adhesive are simultaneously satisfied. The external connection terminals are arranged in an area array, that is, in the form of a lattice on the entire surface of the back surface of the substrate or in one or several rows on the periphery.
[0046]
The organic wiring substrate is not limited to a substrate material such as a polyimide film substrate even if it is an FR-4 substrate such as a BT (bismaleimide) substrate or a glass epoxy substrate. Moreover, although the above-mentioned adhesive film can be formed with the thermosetting adhesive having the above-mentioned physical properties, it is applied to both sides of the polyimide film in order to ensure rigidity when being wound or sent as a tape. A layer structure may be used. We found that it has the same action and effect as described above.
[0047]
The method for adhering the adhesive film to the organic wiring substrate is to cut the adhesive film into a predetermined shape, and then perform accurate positioning of the cut film and thermocompression bonding to the organic wiring substrate.
[0048]
Any method can be used for cutting the adhesive film as long as it accurately cuts the film into a predetermined shape. However, in consideration of workability and affixability, the adhesive film is cut using a punching die, and then organic It is preferable to temporarily press or press-bond the wiring board.
[0049]
For thermocompression bonding of the cut adhesive film to the organic wiring board, after the adhesive film is cut, it is adsorbed to the press material by suction, and after positioning is accurately performed, it is temporarily pressed onto the organic wiring board, and then the heat pressing is performed. There are a method of pressure bonding and a method of punching an adhesive film with a punching die and then temporarily pressing it, followed by a main pressing with a heat press. Further, when a punching die is used, there is a method of subjecting the tape punched with the punching die to main pressure bonding as it is.
[0050]
Temporary pressure bonding may be performed by adhering the punched adhesive tape to the organic wiring substrate, and the conditions are not particularly limited.
[0051]
30-250 degreeC is preferable and the crimping | compression-bonding temperature of the adhesive film at the time of this press-fit is still more preferable 70-150 degreeC. When the pressure bonding pressure is 30 ° C. or lower, not only is the elastic modulus of the adhesive film high and the adhesive strength is low, but also when the adhesive film is bonded onto the wiring of the organic wiring substrate, the embedding property of the adhesive around the wiring is not preferable. If the bonding temperature is 250 ° C. or higher, the wiring is oxidized and the organic wiring board becomes soft, which is not preferable in terms of workability.
[0052]
The pressure for this crimping is 1-20kg / cm ² Is preferably 3 to 10 kg / cm ² Is more preferable. Pressure bonding pressure is 1kg / cm ² Below, the adhesive strength of the adhesive film and the embeddability around the wiring are poor, 20 kg / cm ² As described above, the dimensional accuracy of the adhesive is deteriorated when the adhesive protrudes beyond a predetermined position.
[0053]
The main press-bonding time may be any time that can be bonded at the above-described press-bonding temperature and press-bonding time.
[0054]
The main press for press bonding is preferably one having a release agent on the surface so that the adhesive does not adhere to the press surface, and one using Teflon or silicone is particularly preferable in terms of release properties and workability.
[0055]
The epoxy resin used in the present invention only needs to be cured and exhibit an adhesive action. An epoxy resin that is bifunctional or higher and preferably has a molecular weight of less than 5000, more preferably less than 3000 is used. In particular, it is preferable to use a bisphenol A type or bisphenol F type liquid resin having a molecular weight of 500 or less because the fluidity during lamination can be improved. Bisphenol A type or bisphenol F type liquid resins having a molecular weight of 500 or less are commercially available from Yuka Shell Epoxy Co., Ltd. under the trade names of Epicoat 807, Epicoat 827, and Epicoat 828. In addition, from Dow Chemical Japan, D.C. E. R. 330, D.E. E. R. 331, D.D. E. R. It is marketed under the trade name 361. Further, they are commercially available from Toto Kasei Co., Ltd. under the trade names YD128 and YDF170.
[0056]
As the epoxy resin, a polyfunctional epoxy resin may be added for the purpose of increasing the Tg (glass transition temperature), and examples of the polyfunctional epoxy resin include phenol novolac type epoxy resins and cresol novolac type epoxy resins.
[0057]
The phenol novolac type epoxy resin is commercially available from Nippon Kayaku Co., Ltd. under the trade name EPPN-201. The cresol novolac epoxy resin is commercially available from Sumitomo Chemical Co., Ltd. under the trade names ESCN-001 and ESCN-195, and from Nippon Kayaku Co., Ltd. under the trade names EOCN1012, EOCN1025, and EOCN1027. Yes. Moreover, brominated epoxy resin, brominated bisphenol A type epoxy resin (for example, trade name ESB-400 manufactured by Sumitomo Chemical Co., Ltd.), brominated phenol novolak type epoxy resin (for example, manufactured by Nippon Kayaku Co., Ltd.) as epoxy resins. BREN-105, BREN-S) and the like can be used.
[0058]
As the curing agent for the epoxy resin, those usually used as a curing agent for the epoxy resin can be used, and have at least two amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, and phenolic hydroxyl groups in one molecule. Examples of the compound include bisphenol A, bisphenol F, and bisphenol S. In particular, it is preferable to use phenol novolak resin, bisphenol novolak resin, cresol novolak resin, or the like, which is a phenol resin, because of its excellent electric corrosion resistance during moisture absorption.
[0059]
Such preferable curing agents are trade names such as Phenolite LF2882, Phenolite LF2822, Phenolite TD-2090, Phenolite TD-2149, Phenolite VH4150, Phenolite VH4170 from Dainippon Ink & Chemicals, Inc. It is commercially available. Moreover, tetrabromobisphenol A (trade name Fireguard FG-2000 manufactured by Teijin Chemicals Ltd.), which is a brominated phenol compound, can be used as a curing agent.
[0060]
A curing accelerator is preferably used together with the curing agent, and various imidazoles are preferably used as the curing accelerator. Examples of imidazole include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, and the like.
[0061]
Imidazoles are commercially available from Shikoku Chemical Industry Co., Ltd. under the trade names 2E4MZ, 2PZ-CN, and 2PZ-CNS.
[0062]
High molecular weight resins compatible with epoxy resins and having a weight average molecular weight of 30,000 or more include phenoxy resins, high molecular weight epoxy resins, ultrahigh molecular weight epoxy resins, highly polar functional group-containing rubbers, and highly polar functional group containing Examples include reactive rubber. The weight average molecular weight is 30,000 or more in order to reduce the tackiness of the adhesive in the B stage and improve the flexibility at the time of curing. Examples of the functional group-containing reactive rubber having a large polarity include a rubber obtained by adding a functional group having a large polarity such as a carboxyl group to an acrylic rubber. Here, having compatibility with the epoxy resin means a property of forming a homogeneous mixture without separating from the epoxy resin after curing and separating into two or more phases.
[0063]
Phenoxy resins are commercially available from Toto Kasei Co., Ltd. under trade names such as phenototo YP-40, phenototo YP-50, and phenototo YP-60. The high molecular weight epoxy resin is a high molecular weight epoxy resin having a molecular weight of 30,000 to 80,000, and an ultra high molecular weight epoxy resin having a molecular weight exceeding 80,000 (Japanese Patent Publication No. 7-59617, Japanese Patent Publication No. 7-59618, Japanese Patent Publication No. 7-59619, Japanese Patent Publication No. 7-59620, Japanese Patent Publication No. 7-64911, and Japanese Patent Publication No. 7-68327), all of which are manufactured by Hitachi Chemical Co., Ltd. As a functional group-containing reactive rubber having a large polarity, a carboxyl group-containing acrylic rubber is commercially available from Teikoku Chemical Industry Co., Ltd. under the trade name HTR-860P.
[0064]
The addition amount of the high molecular weight resin having compatibility with the above epoxy resin and having a weight average molecular weight of 30,000 or more is insufficient in the flexibility of the phase mainly composed of epoxy resin (hereinafter referred to as epoxy resin phase) In order to prevent a decrease in insulation due to reduction or cracks, the amount is 10 parts by weight or more, and in order to prevent a decrease in Tg of the epoxy resin phase, the amount is 40 parts by weight or less.
[0065]
An epoxy group-containing acrylic copolymer containing 2 to 6% by weight of glycidyl (meth) acrylate and having a Tg of −10 ° C. or more and a weight average molecular weight of 800,000 or more is commercially available from Teikoku Chemical Industry Co., Ltd. The trade name HTR-860P-3 can be used. When the functional group monomer is carboxylic acid type acrylic acid or hydroxyl group type hydroxymethyl (meth) acrylate, the crosslinking reaction is likely to proceed, resulting in gelation in the varnish state and an increase in the degree of cure in the B stage state. This is not preferable because of problems such as a decrease in adhesive strength. The amount of glycidyl (meth) acrylate used as the functional group monomer is 2 to 6% by weight of the copolymer. In order to obtain an adhesive force, the content is made 2% by weight or more, and in order to prevent gelation of rubber, the content is made 6% by weight or less. The balance can be ethyl (meth) acrylate, butyl (meth) acrylate or a mixture of both, but the mixing ratio is determined in consideration of the Tg of the copolymer. When Tg is less than −10 ° C., the tackiness of the adhesive film in the B-stage state is increased and the handleability is deteriorated. Examples of the polymerization method include pearl polymerization and solution polymerization, and these can be obtained.
[0066]
This is because the epoxy group-containing acrylic copolymer has a weight average molecular weight of 800,000 or more, and within this range, there is little decrease in strength and flexibility and increase in tackiness in sheet form and film form.
[0067]
The epoxy group-containing acrylic copolymer is added in an amount of 100 parts by weight or more in order to prevent a decrease in film strength and an increase in tackiness. When the amount of the epoxy group-containing acrylic rubber is increased, the rubber component Therefore, the amount of the epoxy resin phase is decreased and the handling property at high temperature is lowered.
[0068]
In order to improve the interfacial bond between different materials, a coupling agent can be blended in the adhesive. As the coupling agent, a silane coupling agent is preferable.
[0069]
As the silane coupling agent, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-ureidopropyltriethoxysilane, N-β-aminoethyl-γ- Examples include aminopropyltrimethoxysilane.
[0070]
In the silane coupling agent, γ-glycidoxypropyltrimethoxysilane is NUC A-187, γ-mercaptopropyltrimethoxysilane is NUC A-189, γ-aminopropyltriethoxysilane is NUC A-1100, γ. -Ureidopropyltriethoxysilane is a product name of NUC A-1160, N-β-aminoethyl-γ-aminopropyltrimethoxysilane is NUC A-1120, both of which are commercially available from Nippon Unicar Co., Ltd. Can be used.
[0071]
The blending amount of the coupling agent is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin from the effects of addition, heat resistance and cost.
[0072]
Furthermore, an ion scavenger can be blended in order to adsorb ionic impurities and improve insulation reliability during moisture absorption. The compounding amount of the ion scavenger is preferably 5 to 10 parts by weight from the effect of addition, heat resistance, and cost. As the ion scavenger, a compound known as a copper damage inhibitor, for example, a triazine thiol compound or a bisphenol-based reducing agent can be blended in order to prevent copper from being ionized and dissolved. Examples of the bisphenol-based reducing agent include 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 4,4′-thio-bis- (3-methyl-6-tert-butylphenol). Etc.
[0073]
A copper damage inhibitor comprising a triazine thiol compound as a component is commercially available from Sankyo Pharmaceutical Co., Ltd. under the trade name Disnet DB. Moreover, the copper damage inhibitor which uses a bisphenol-type reducing agent as a component is marketed by Yoshitomi Pharmaceutical Co., Ltd. by the brand name Yoshinox BB.
[0074]
Furthermore, inorganic fillers are used for the purpose of improving the handling and thermal conductivity of the adhesive, imparting flame retardancy, adjusting melt viscosity, imparting thixotropic properties, and improving surface hardness. It is preferable to mix 2 to 20 parts by volume with respect to 100 parts by volume of the adhesive resin component. From the viewpoint of the effect of blending, if the blending amount is 2 parts by volume or more and the blending amount increases, problems such as an increase in storage elastic modulus of the adhesive, a decrease in adhesiveness, and a decrease in electrical properties due to residual voids occur, so 20 parts by volume. It is as follows.
[0075]
As inorganic fillers, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina powder, aluminum nitride powder, aluminum borate whisker, boron nitride powder, crystallinity Examples thereof include silica and amorphous silica.
[0076]
In order to improve thermal conductivity, alumina, aluminum nitride, boron nitride, crystalline silica, amorphous silica and the like are preferable.
[0077]
Of these, alumina is preferable in terms of good heat dissipation, heat resistance, and insulation. In addition, crystalline silica or amorphous silica is inferior to alumina in terms of heat dissipation, but has low ionic impurities, so it has high insulation during PCT treatment, and corrosion of copper foil, aluminum wire, aluminum plate, etc. It is preferable in terms of few points.
[0078]
In order to impart flame retardancy, aluminum hydroxide, magnesium hydroxide, antimony trioxide and the like are preferable.
[0079]
For the purpose of adjusting melt viscosity and imparting thixotropic properties, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, crystalline silica, non-crystalline silica Crystalline silica and the like are preferred.
[0080]
For improving the surface hardness, short fiber alumina, aluminum borate whisker or the like is preferable.
[0081]
The adhesive film of the present invention is obtained by forming an adhesive layer on a base film by dissolving or dispersing each component of the adhesive in a solvent to form a varnish, coating the base film, heating and removing the solvent. It is done. As the base film, a plastic film such as a polytetrafluoroethylene film, a polyethylene terephthalate film, a release-treated polyethylene terephthalate film, a polyethylene film, a polypropylene film, a polymethylpentene film, or a polyimide film can be used. The base film can be peeled off at the time of use, and only the adhesive film can be used, or the base film can be used together with the base film and removed later.
[0082]
Examples of the plastic film used in the present invention include polyimide films such as Kapton (trade name, manufactured by Toray, DuPont) and Apical (trade name, manufactured by Kaneka Chemical Co., Ltd.), Lumirror (trade name, manufactured by Toray, DuPont). ), Polyethylene terephthalate film such as Purex (trade name, manufactured by Teijin Ltd.) and the like can be used.
[0083]
As the varnishing solvent, methyl ethyl ketone, acetone, methyl isobutyl ketone, 2-ethoxyethanol, toluene, butyl cellosolve, methanol, ethanol, 2-methoxyethanol or the like having a relatively low boiling point is preferably used. Moreover, you may add a high boiling point solvent for the purpose of improving coating-film property. Examples of the high boiling point solvent include dimethylacetamide, dimethylformamide, methylpyrrolidone, and cyclohexanone.
[0084]
When considering dispersion of the inorganic filler, the varnish can be manufactured using a raking machine, a three-roller, a bead mill, or the like, or a combination thereof. By mixing the filler and the low molecular weight material in advance and then blending the high molecular weight material, the time required for mixing can be shortened. In addition, after forming the varnish, it is preferable to remove bubbles in the varnish by vacuum degassing.
[0085]
The adhesive varnish is applied onto a base film such as the plastic film and the solvent is removed by heating and drying. The resulting adhesive is 10 to 40% of the total curing calorific value measured using DSC. It is assumed that the heat generation has ended. When the solvent is removed, heating is performed. At this time, the curing reaction of the adhesive composition proceeds and gelation occurs. The cured state at that time affects the fluidity of the adhesive and optimizes the adhesiveness and handleability. DSC (Differential Scanning Calorimetry) is based on the zero principle method that supplies or removes heat so that the temperature difference from a standard sample that does not generate heat or endotherm is constantly canceled within the measurement temperature range. An apparatus is commercially available and can be measured using it. The reaction of the resin composition is an exothermic reaction, and when the temperature of the sample is increased at a constant rate of temperature increase, the sample reacts to generate heat. The calorific value is output to a chart, the area surrounded by the calorific curve and the base line is obtained with the baseline as a reference, and this is defined as the calorific value. Measure from the room temperature to 250 ° C. at a rate of temperature increase of 5 to 10 ° C./min to obtain the heat generation amount described above. Some of these are performed automatically, and can be easily performed by using them. Next, the calorific value of the adhesive obtained by applying to the base film and drying is determined as follows. First, the total calorific value of an uncured sample obtained by drying the solvent using a vacuum dryer at 25 ° C. is measured, and this is defined as A (J / g). Next, the calorific value of the coated and dried sample is measured. The degree of cure C (%) of the sample (the state in which heat generation is finished by heating and drying) is given by the following mathematical formula (1).
[0086]
C (%) = (A−B) × 100 / A (1)
The storage elastic modulus measured by the dynamic viscoelasticity measuring apparatus of the adhesive of the present invention should be a low elastic modulus of 20 to 2,000 MPa at 25 ° C. and 3 to 50 MPa at 260 ° C. The storage elastic modulus is measured by applying a tensile load to the cured adhesive (adhesive that has generated 95-100% of the total calorific value when measured using DSC), a frequency of 10 Hz, and a heating rate. The measurement was performed in a temperature-dependent measurement mode in which measurement was performed at 5 to 10 ° C / min from -50 ° C to 300 ° C. When the storage elastic modulus at 25 ° C. exceeds 2,000 MPa, cracks are generated because the effect of relieving stress generated during reflow is reduced due to the difference in thermal expansion coefficient between the semiconductor chip and the printed wiring board. On the other hand, when the storage elastic modulus is less than 20 MPa, the handling property of the adhesive is deteriorated. Preferably it is 50-1000 MPa.
[0087]
The present invention is characterized in that an epoxy group-containing acrylic copolymer and an epoxy resin adhesive have a low elastic modulus near room temperature. Since the epoxy group-containing acrylic copolymer has a low elastic modulus near room temperature, increasing the mixing ratio of the epoxy group-containing acrylic copolymer increases the difference in thermal expansion coefficient between the semiconductor chip and the printed wiring board. As a result, cracks can be suppressed by the effect of relieving the stress generated in the heating and cooling process during reflow. Moreover, since the epoxy group-containing acrylic copolymer is excellent in reactivity with the epoxy resin, the adhesive cured product is chemically and physically stable, and therefore exhibits excellent performance in a moisture resistance test represented by PCT treatment. . In addition, the following methods solved problems in terms of handling properties such as a decrease in strength, a decrease in flexibility, and an increase in tackiness of conventional adhesive films.
1) By using the epoxy group-containing acrylic copolymer defined in the present invention, the occurrence of cracks during reflow can be suppressed.
2) By using an acrylic copolymer having a large molecular weight, the film strength and flexibility of the adhesive film can be ensured even when the addition amount of the copolymer is small.
3) The tackiness can be reduced by adding a high molecular weight resin that is compatible with the epoxy resin and has a weight average molecular weight of 30,000 or more.
[0088]
Furthermore, in the adhesive of the present invention, the epoxy resin and the high molecular weight resin are well compatible and uniform, and the epoxy group contained in the acrylic copolymer partially reacts with them to form an unreacted epoxy. Since the entire resin is cross-linked and gelled, it suppresses the fluidity and does not impair the handleability even when it contains a large amount of epoxy resin or the like. In addition, since many unreacted epoxy resins remain in the gel, when pressure is applied, unreacted components ooze out from the gel, so even if the whole gels, the decrease in adhesiveness is reduced. .
[0089]
When the adhesive is dried, epoxy groups and epoxy resins contained in the epoxy group-containing acrylic copolymer react together, but the epoxy group-containing acrylic copolymer has a large molecular weight and many epoxy groups in one molecular chain. Since it is contained, gelation occurs even when the reaction proceeds slightly. Usually, gelation occurs in a state where heat generation of 10 to 40% of the total curing heat generation amount measured using DSC is completed, that is, in the first half of the A or B stage. Therefore, it gels in a state containing a large amount of unreacted components such as an epoxy resin, and the melt viscosity is greatly increased as compared with the case where the melt viscosity is not gelled, and the handling property is not impaired. In addition, when pressure is applied, unreacted components ooze out from the gel, so even when gelled, there is little decrease in adhesion. Furthermore, since the adhesive can be formed into a film in a state containing many unreacted components such as an epoxy resin, there is an advantage that the life (effective use period) of the adhesive film becomes long.
[0090]
In conventional epoxy resin adhesives, gelation occurs for the first time in the C stage state from the second half of the B stage, and since there are few unreacted components such as epoxy resin at the stage where gelation has occurred, the fluidity is low and the pressure is low. Even when applied, the adhesiveness is lowered because less unreacted components ooze out from the gel.
[0091]
Although it is not clear how easily the epoxy group contained in the acrylic copolymer reacts with the epoxy group of the low molecular weight epoxy resin, it should have at least the same degree of reactivity. It is not necessary that only the epoxy group contained in the polymer react selectively.
[0092]
In this case, A, B, and C stages indicate the degree of curing of the adhesive. The A stage is almost uncured and not gelled, and is a state in which heat generation of 0 to 20% of the total curing calorific value when measured using DSC is completed. The B stage is a state in which the curing and gelation have progressed slightly, and the heat generation of 20 to 60% of the total curing heat generation amount is finished. The C stage is in a state of being hardened and gelled, and is in a state in which heat generation of 60 to 100% of the total heat generation amount of heat is finished.
[0093]
The gelation is determined by immersing the adhesive in a highly permeable solvent such as THF (tetrahydrofuran), leaving it to stand at 25 ° C. for 20 hours, and then swelling the adhesive without dissolving it completely. It was determined that Experimentally, the determination was made as follows.
[0094]
The adhesive (weight W1) was immersed in THF and allowed to stand at 25 ° C. for 20 hours, and then the undissolved portion was filtered through a 200-mesh nylon cloth, and the weight after drying was measured (weight W2). The THF extraction rate (%) was calculated as the following formula (2). A sample having a THF extraction rate exceeding 80% by weight was regarded as not gelled, and a sample having 80% by weight or less was judged to be gelled.

[0095]
In the present invention, by adding a filler, the melt viscosity can be increased and thixotropic properties can be exhibited, so that the above effect can be further increased.
[0096]
Furthermore, in addition to the above effects, it is possible to impart characteristics such as improvement in heat dissipation of the adhesive, imparting flame retardancy to the adhesive, imparting an appropriate viscosity at the temperature during adhesion, and improvement in surface hardness. The semiconductor device in which the semiconductor chip and the wiring board are bonded using the adhesive film of the present invention was excellent in reflow resistance, temperature cycle test, electric corrosion resistance, moisture resistance (PCT resistance) and the like.
[0097]
The heat-resistant thermoplastic film used for the core material in the present invention is preferably a film using a polymer or a liquid crystal polymer having a glass transition temperature Tg of 200 ° C. or higher, and polyimide, polyethersulfone, polyamideimide, polyetherimide. Alternatively, wholly aromatic polyesters are preferably used. The thickness of the film is preferably used within the range of 5 to 200 μm, but is not limited. When a thermoplastic film having a Tg of 200 ° C. or lower is used as the core material, plastic deformation may occur at a high temperature such as during solder reflow, which is not preferable.
[0098]
The adhesive formed on both surfaces of the core material according to the present invention dissolves or disperses each component of the adhesive in a solvent to form a varnish, which is applied onto a heat-resistant thermoplastic film as the core material and heated to remove the solvent. It is possible to produce a double-sided adhesive film having a three-layer structure by forming an adhesive layer on a heat-resistant thermoplastic film as a core material. The thickness of the adhesive is used in the range of 2 to 150 μm, and if it is thinner than this, the adhesiveness and thermal stress buffering effect are poor, and if it is thick, it is not economical, but it is not limited.
[0099]
In addition, each component of the adhesive is dissolved or dispersed in a solvent to form a varnish, and this varnish is applied onto the base film, heated to remove the solvent, thereby producing an adhesive film consisting only of the adhesive component. A double-sided adhesive film having a three-layer structure can also be obtained by laminating an adhesive film consisting only of components on both sides of a heat-resistant thermoplastic film as a core material. Here, as a base film for producing an adhesive film composed only of an adhesive component, a polytetrafluoroethylene film, a polyethylene terephthalate film, a release-treated polyethylene terephthalate film, a polyethylene film, a polypropylene film, a polymethylpentene film, A plastic film such as a polyimide film can be used. Examples of the plastic film include polyimide films such as Kapton (trade name, manufactured by Toray, DuPont), Apical (trade name, manufactured by Kaneka Chemical Co., Ltd.), Lumirror (trade name, manufactured by Toray, DuPont), and Purex. A polyethylene terephthalate film such as (trade name, manufactured by Teijin Ltd.) can be used.
[0100]
As the varnishing solvent, methyl ethyl ketone, acetone, methyl isobutyl ketone, 2-ethoxyethanol, toluene, butyl cellosolve, methanol, ethanol, 2-methoxyethanol or the like having a relatively low boiling point is preferably used. Moreover, you may add a high boiling point solvent for the purpose of improving coating-film property. Examples of the high boiling point solvent include dimethylacetamide, dimethylformamide, methylpyrrolidone, and cyclohexanone.
[0101]
When considering dispersion of the inorganic filler, the varnish can be manufactured using a raking machine, a three-roller, a bead mill, or the like, or a combination thereof. By mixing the filler and the low molecular weight material in advance and then blending the high molecular weight material, the time required for mixing can be shortened. In addition, after forming the varnish, it is preferable to remove bubbles in the varnish by vacuum degassing.
[0102]
The adhesive is obtained by applying an adhesive varnish on a base film such as a heat-resistant thermoplastic film or plastic film as a core material, and drying by heating to remove the solvent. The adhesive obtained thereby Is preferably in a state where heat generation of 10 to 40% of the total curing heat generation amount measured using DSC is completed. When the solvent is removed, heating is performed. At this time, the curing reaction of the adhesive composition proceeds and gelation occurs. The cured state at that time affects the fluidity of the adhesive and optimizes the adhesiveness and handleability. DSC (Differential Scanning Calorimetry) is based on the zero principle method that supplies or removes heat so that the temperature difference from a standard sample that does not generate heat or endotherm is constantly canceled within the measurement temperature range. An apparatus is commercially available and can be measured using it. The reaction of the resin composition is an exothermic reaction, and when the temperature of the sample is increased at a constant rate of temperature increase, the sample reacts to generate heat. The calorific value is output to a chart, the area surrounded by the calorific curve and the base line is obtained with the baseline as a reference, and this is defined as the calorific value. Measure from the room temperature to 250 ° C. at a rate of temperature increase of 5 to 10 ° C./min to obtain the heat generation amount described above. Some of these are performed automatically, and can be easily performed by using them.
[0103]
The calorific value of the adhesive obtained by applying to the heat-resistant thermoplastic film or base film as the core material and drying is determined as follows. First, only the adhesive component is taken out, and the total calorific value of an uncured sample obtained by drying the solvent at 25 ° C. using a vacuum dryer is measured, and this is defined as A (J / g). Next, the calorific value of the coated and dried sample is measured. The degree of cure C (%) of the sample (the state in which heat generation is finished by heating and drying) is given by the following mathematical formula (1).
[0104]
C (%) = (A−B) × 100 / A (1)
The storage elastic modulus measured by the dynamic viscoelasticity measuring apparatus for the adhesive component of the present invention is preferably a low elastic modulus of 20 to 2,000 MPa at 25 ° C. and 3 to 50 MPa at 260 ° C. The storage elastic modulus was measured in a temperature-dependent measurement mode in which a tensile load was applied to the cured adhesive and the temperature was measured from −50 ° C. to 300 ° C. at a frequency of 10 Hz and a temperature increase rate of 5 to 10 ° C./min. When the storage elastic modulus at 25 ° C. exceeds 2,000 MPa, cracks are generated because the effect of relieving stress generated during reflow is reduced due to the difference in thermal expansion coefficient between the semiconductor chip and the printed wiring board. On the other hand, when the storage elastic modulus is less than 20 MPa, the handleability is deteriorated.
[0105]
In the present invention, by taking a three-layer structure using a heat-resistant thermoplastic film as the core material, the epoxy group-containing acrylic copolymer and the epoxy resin adhesive have a low elastic modulus near room temperature. It is characterized by easy handling of the adhesive film. That is, the three-layer structure of the present invention can easily automate operations such as alignment of a non-rigid adhesive film near room temperature, and exhibits the excellent thermal stress relaxation effect of the adhesive system. be able to. In the present invention, the problem in terms of handleability due to a decrease in rigidity of a conventional low elastic modulus adhesive film is solved by the following method.
1) By adopting a three-layer structure in which a heat-resistant thermoplastic film is arranged on the core material, a low elastic modulus adhesive can be easily handled in the form of a film.
2) Plastic deformation of the adhesive film during reflow can be suppressed by using a heat-resistant thermoplastic film serving as a core material defined in the present invention.
[0106]
Furthermore, in the present invention, the epoxy resin and the high molecular weight resin are compatible and uniform, and the epoxy group contained in the acrylic copolymer partially reacts with them to include an unreacted epoxy resin. Since the whole is cross-linked and gelled, it suppresses the fluidity and does not impair the handleability even when it contains a large amount of epoxy resin or the like. In addition, since many unreacted epoxy resins remain in the gel, when pressure is applied, unreacted components ooze out from the gel, so that even when the whole gels, the decrease in adhesiveness is reduced. .
[0107]
When the adhesive is dried, epoxy groups and epoxy resins contained in the epoxy group-containing acrylic copolymer react together, but the epoxy group-containing acrylic copolymer has a large molecular weight and many epoxy groups in one molecular chain. Since it is contained, it gels even when the reaction proceeds slightly. Usually, gelation occurs in a state where heat generation of 10 to 40% of the total curing heat generation amount measured using DSC is completed, that is, in the first half of the A or B stage. Therefore, it gels in a state containing a large amount of unreacted components such as an epoxy resin, and the melt viscosity is greatly increased as compared with the case where the melt viscosity is not gelled, and the handling property is not impaired. Further, when pressure is applied, unreacted components ooze out from the gel, so that even when gelled, there is little decrease in adhesion. Furthermore, since the adhesive can be formed into a film in a state containing many unreacted components such as an epoxy resin, there is an advantage that the life (effective use period) of the adhesive film becomes long.
[0108]
In conventional epoxy resin adhesives, gelation occurs for the first time in the C stage state from the second half of the B stage, and since there are few unreacted components such as epoxy resin at the stage where gelation has occurred, the fluidity is low and the pressure is low. Even when applied, the adhesiveness is lowered because less unreacted components ooze out from the gel.
[0109]
Although it is not clear how easily the epoxy group contained in the acrylic copolymer reacts with the epoxy group of the low molecular weight epoxy resin, it should have at least the same degree of reactivity. It is not necessary that only the epoxy group contained in the polymer react selectively.
[0110]
In this case, A, B, and C stages indicate the degree of curing of the adhesive. The A stage is almost uncured and not gelled, and is a state in which heat generation of 0 to 20% of the total curing calorific value when measured using DSC is completed. The B stage is a state in which the curing and gelation have progressed slightly, and the heat generation of 20 to 60% of the total curing heat generation amount is finished. The C stage is in a state of being hardened and gelled, and is in a state in which heat generation of 60 to 100% of the total heat generation amount of heat is finished.
[0111]
The gelation is determined by immersing the adhesive in a highly permeable solvent such as THF (tetrahydrofuran), leaving it to stand at 25 ° C. for 20 hours, and then swelling the adhesive without dissolving it completely. It was determined that Experimentally, the determination was made as follows.
[0112]
The adhesive (weight W1) was immersed in THF and allowed to stand at 25 ° C. for 20 hours, and then the undissolved portion was filtered through a 200-mesh nylon cloth, and the weight after drying was measured (weight W2). The THF extraction rate (%) was calculated as the following formula (2). A sample having a THF extraction rate exceeding 80% by weight was regarded as not gelled, and a sample having 80% by weight or less was judged to be gelled.

[0113]
In the present invention, by adding a filler, the melt viscosity can be increased and thixotropic properties can be exhibited, so that the above effect can be further increased.
[0114]
Furthermore, in addition to the effects described above, it is possible to impart properties such as improved heat dissipation of the adhesive, imparting flame retardancy to the adhesive, imparting an appropriate viscosity at the bonding temperature, and improving surface hardness.
(Brief description of the drawings)
FIG. 1 (a) is a cross-sectional view of a single-layer thermosetting adhesive film according to the present invention, and FIG. 1 (b) is a cross-sectional view of a three-layer adhesive film according to the present invention.
[0115]
FIG. 2 is a cross-sectional view of a semiconductor mounting substrate in which an adhesive member is thermocompression bonded to an organic wiring substrate.
[0116]
FIG. 3 is a cross-sectional view of a semiconductor mounting substrate in which an adhesive member is thermocompression bonded to an organic wiring substrate.
[0117]
FIG. 4 is a cross-sectional view of the semiconductor device of the present invention.
[0118]
FIG. 5 is a cross-sectional view of another example of the semiconductor device of the present invention.
[0119]
FIG. 6 is a cross-sectional view showing a manufacturing process of an embodiment of a semiconductor mounting substrate and a semiconductor device.
[0120]
FIG. 7 is a cross-sectional view showing a manufacturing process of another embodiment of the semiconductor mounting substrate and the semiconductor device.
[0121]
FIG. 8 is a cross-sectional view of another example of the semiconductor device of the present invention. (Best Mode for Carrying Out the Invention)
Various embodiments of the present invention will be described below with reference to the drawings.
<Example 1>
FIG. 1 (a) is a cross-sectional view of a single-layer thermosetting adhesive film, in which the cured product has a modulus of elasticity at 25 ° C. of 10 to 2000 MPa as measured by a dynamic viscoelastic device, and 260 ° C. The semi-cured thermosetting adhesive 1 having an elastic modulus in the range of 3 to 50 MPa and having finished heat generation of 10 to 40% of the total curing calorific value when measured using a DSC (differential calorimeter) Consists of. An epoxy group-containing acrylic copolymer film dried to a solvent content of 2% or less remaining in the thermosetting adhesive film was used.
[0122]
FIG. 1 (b) shows a cross-sectional view of a three-layer adhesive film in which the thermosetting adhesive 1 is applied to both surfaces of the polyimide film 2. In this example, 50 μm thick Upilex (trade name) manufactured by Ube Industries was used as the polyimide film.
[0123]
FIG. 2 is a cross-sectional view of a semiconductor mounting substrate in which the adhesive member 3 is thermocompression bonded to the organic wiring substrate 4 and is suitable for connecting the semiconductor terminal portion and the wiring substrate side terminal portion by wire bonding. FIG. It is sectional drawing of the board | substrate for semiconductor mounting which bonded the adhesive member 3 to the tape-shaped wiring board 5, and was suitable for connecting with a semiconductor terminal part and a wiring board side terminal part by an inner bonding system. FIG. 4 shows a semiconductor device in which a chip 6 is bonded face-up to the semiconductor mounting substrate of FIG. 2, and a semiconductor terminal portion and a wiring board side terminal portion are wire-bonded by wires 7 and sealed with a sealing material. FIG. 5 is a cross-sectional view, FIG. 5 shows that the chip 6 is bonded face-down to the semiconductor mounting substrate of FIG. 3, and then the semiconductor terminal portion and the substrate-side terminal portion are connected by the TAB inner bonding method. FIG. 8 is a cross-sectional view of a semiconductor device sealed with 8. In addition, as shown in FIG. 8, you may form the wiring 9 on the opposite side to the semiconductor chip mounting side of a board | substrate. In this case, the external connection terminal 12 is formed on the surface of the wiring 9 formed on the side opposite to the semiconductor chip mounting side. The exposed portion of the wiring 9 is covered with a resist 11.
[0124]
FIG. 6 shows a manufacturing process of a semiconductor mounting substrate and a semiconductor device.
[0125]
When the elastic modulus at 25 ° C. of the cured product measured with a dynamic viscoelastic device is in the range of 10 to 2000 MPa and the elastic modulus at 260 ° C. is specified in the range of 3 to 50 MPa, and measured using DSC A thermosetting adhesive tape (adhesive member) 3 composed of a semi-cured thermosetting adhesive 1 that has finished generating 10 to 40% of the total amount of heat generated is cut into a predetermined size with a cutting press. (FIG. 6A).
[0126]
The cut thermosetting adhesive tape 3 is precisely aligned with the upper surface of the polyimide film substrate (organic wiring substrate) 4 on which one layer of Cu wiring is provided and through-holes for external solder terminals are formed, and then hot press The semiconductor mounting substrate is obtained by thermocompression bonding with (FIG. 6B).
[0127]
In this example, cutting of the thermosetting adhesive film, precise positioning on the polyimide film substrate, and temporary fixing are performed individually, and then the thermosetting adhesive film thus mounted is collectively subjected to main pressure bonding with a hot press. Seven frame-shaped semiconductor mounting substrates were obtained. Further, in this example, before the step of cutting the thermosetting adhesive film 3, an eliminostat (static charge removal) step of blowing charged air is performed, and the charged insulating film is attached to the jig during the cutting step. Prevented sticking. Further, the upper mold of the heat press that contacts the thermosetting adhesive film 3 during temporary bonding and main bonding in a lump is subjected to a Teflon or silicon release surface treatment so that the thermosetting film becomes the upper mold. Prevents sticking. A chip mounting step is performed in which the semiconductor chip 6 is precisely positioned and mounted on the frame substrate for mounting multiple semiconductors thus obtained face-up, and is pressed and bonded by hot press. In this example, the heating temperature on the semiconductor chip side is set higher than at least the semiconductor mounting substrate side, and heating and pressure bonding are performed from both sides.
[0128]
Thereafter, a wire bonding step (FIG. 6 (c)) for wire bonding the terminal portion on the semiconductor chip side and the substrate side terminal portion with a gold wire, and sealing by transfer molding with an epoxy-based sealing material The semiconductor device according to the present invention was obtained through the process (FIG. 6D) and the solder ball forming process of mounting the solder balls and forming the external terminals 9 through the reflow process (FIG. 6E). Hitachi Chemical's biphenyl epoxy sealing material CEL-9200 (trade name) was used as the sealing material 8.
<Comparative Example 1>
On the upper surface of a polyimide film wiring board (same as used in Example 11) on which one layer of Cu wiring is provided and through-holes for external solder terminals are formed, an epoxy resin as a main component and the cured product DMA ( An insulating liquid adhesive having an elastic modulus of 25 MPa measured at 25 ° C. measured with a dynamic viscoelasticity measuring device was dropped and applied with a die bonder, and the semiconductor chip was precisely positioned and mounted. Thereafter, after a predetermined curing time in a clean oven, the same wire bonding process, sealing process, and solder ball forming process as in Example 1 were performed to obtain a semiconductor device.
<Comparative example 2>
On the same polyimide wiring board as used in Example 1, an insulating liquid whose main component is silicon resin and whose cured product has an elastic modulus at 25 ° C. of 10 MPa and whose elastic modulus at 260 ° C. cannot be measured is small. Adhesive was dropped and applied with a die bonder to mount a semiconductor chip, and then the same process as in Example 1 was followed to obtain a semiconductor device.
<Example 2>
FIG. 7 shows a manufacturing process of a semiconductor mounting substrate and a semiconductor device.
[0129]
When the elastic modulus at 25 ° C. of the cured product measured with a dynamic viscoelastic device is in the range of 10 to 2000 MPa and the elastic modulus at 260 ° C. is specified in the range of 3 to 50 MPa, and measured using DSC A thermosetting adhesive tape (adhesive member) 3 composed of a semi-cured thermosetting adhesive 1 that has finished generating 10 to 40% of the total amount of heat generated is cut into a predetermined size with a cutting press. (FIG. 7A).
[0130]
The cut thermosetting adhesive tape 3 is precisely aligned with the upper surface of the polyimide film substrate 5 on which one layer of Cu wiring is provided and the inner lead portion and the through hole for the external solder terminal are formed as in the TAB tape. After that, a semiconductor mounting substrate was obtained by thermocompression bonding with a hot press (FIG. 7B).
[0131]
In this example, a frame substrate for mounting multiple semiconductors was obtained in the same process in which the static elimination process before the cutting process described in Example 1 and the release surface treatment on the upper mold surface of the hot press were performed.
[0132]
Thereafter, the semiconductor chips 6 were precisely aligned face-down on the semiconductor mounting frame substrate and sequentially mounted, and thermocompression bonded by a hot press (FIG. 7C). Thereafter, the Cu inner lead portion 10 which is the substrate side terminal is individually connected to the chip side terminal portion using a TAB inner lead bonder (in this example, a single point bonder) (FIG. 7D). ) The chip end surface and the upper surface of the polyimide film substrate 5 were coated with an epoxy-based liquid sealing material 8 with a dispense (FIG. 7E), and a semiconductor device was obtained after a predetermined heating / curing time (FIG. 7). 7 (f)). In this example, the inner lead portion used was Sn plated on Cu, and the semiconductor terminal portion was formed with Au plating bumps and connected by Au / Sn bonding.
<Comparative Example 3>
On the top surface of the same polyimide film substrate as in Example 2 where one layer of Cu wiring is applied and the inner lead portion of the TAB tape and the through hole for the external solder terminal are formed, the epoxy resin is the main component and the cured product An insulating liquid adhesive having an elastic modulus at 25 ° C. measured by DMA of 3000 MPa was dropped and applied with a die bonding apparatus, and the semiconductor chip was precisely positioned and mounted. However, although the resin flowed to the inner bonding part and subsequent inner bonding was not possible, the chip end surface was sealed with a liquid sealing material mainly composed of epoxy resin as in Example 2 to form solder balls. A comparative product was obtained.
<Comparative example 4>
On the upper surface of the same polyimide film substrate as in Example 2 in which one layer of Cu wiring is applied, and the inner lead portion of the TAB tape and the through hole for the external solder terminal are formed, the main component of silicon resin is 25 An insulating liquid adhesive having an elastic modulus at 10 ° C. of 10 MPa and an elastic modulus at 260 ° C. that is too small to be measured was dropped and applied with a die bonder, and a semiconductor chip was mounted in the same manner as in Example 2. However, although the resin flowed to the inner bonding part and subsequent inner bonding was not possible, the chip end surface was sealed with a liquid sealing material mainly composed of epoxy resin as in Example 2 to form solder balls. A comparative product was obtained.
<Comparative Example 5>
An insulating liquid adhesive having a silicon resin as a main component and an elastic modulus at 25 ° C. of the cured product of 10 MPa and an elastic modulus at 260 ° C. that cannot be measured is cast on a Teflon plate. It was cured by heating temperature and time to obtain a low elastic film. A thermosetting adhesive mainly composed of an epoxy resin described in Comparative Example 3 is applied to both surfaces of this film, one layer of Cu wiring is applied, and the inner lead portion of the TAB tape and the through hole for the external solder terminal The upper surface of the same polyimide film substrate as in Example 2 was thermocompression bonded by hot pressing, and then the semiconductor chip was bonded face down, and then the inner lead bonding process and the sealing process described in Example 2 were performed. A comparative product having solder balls formed was obtained.
About the semiconductor device of Example 1, Example 2, and Comparative Examples 1-5, while implementing a moisture absorption reflow test, the result of having implemented the temperature-resistant cycle test about each semiconductor device reflow-mounted on the FR-4 wiring board is shown. Table 1 shows. For the moisture absorption reflow test, SAT (ultrasonic exploration) was used to remove delamination and cracks in the specimens that had been subjected to IR reflow at a maximum temperature of 240 ° C after absorbing moisture for 24 hours and 48 hours under conditions of 85 ° C and 85% RH. The results of the investigation with the flaw detector were displayed. In addition, the temperature resistance cycle test of each sample was conducted after a temperature cycle of −25 ° C. (30 minutes, air) to 150 ° C. (30 minutes, air) after mounting on the substrate, and then the solder ball connection resistance of the package external terminals was determined. Those measured by the 4-terminal method and having reached 50 mΩ or more were regarded as defective.

[0133]
(note)
Reflow resistance
○: Exfoliation and voids are very little at the interface between the chip 6 and the organic wiring substrates 4 and 5 and the thermosetting adhesive 3, and cannot be detected by an SAT (ultrasonic inspection flaw detector).
(Triangle | delta): At the time of application | coating of the thermosetting adhesive agent 3, it is 2-3 in the sample 10 that the embedding between the wiring of an organic wiring board is not enough but a void is observed and peeling has progressed from the location.
X: The above-described peeling reaches the outside of the package, and after reflow, the package swells and cracks are observed, but 10 in the sample 10. What is peeled off and reaches the wire bonding part or the inner lead part is observed.
Temperature cycle resistance
○: The connection resistance of the solder ball connection portion does not change.
X: There is even one terminal whose connection resistance of the solder ball connection portion exceeds 50 mΩ.
-: Inner bonding is not possible and connection resistance cannot be measured. Cannot be evaluated.
<Example 3>
As an epoxy resin, bisphenol A type epoxy resin (epoxy equivalent 200, using Epicoat 828 manufactured by Yuka Shell Epoxy Co., Ltd.) 45 parts by weight, cresol novolac type epoxy resin (epoxy equivalent 220, ESCN001 manufactured by Sumitomo Chemical Co., Ltd.) ) 15 parts by weight, 40 parts by weight of phenol novolac resin (using Dainippon Ink Chemical Co., Ltd. priofen LF2882) as a curing agent for epoxy resin, compatible with epoxy resin and having a weight average molecular weight of 30,000 or more 15 parts by weight of phenoxy resin (molecular weight 50,000, using Phenotote YP-50 manufactured by Toto Kasei Co., Ltd.) as the high molecular weight resin, epoxy group-containing acrylic rubber (molecular weight 1 million, Teikoku Chemical Industry Co., Ltd.) as the epoxy group-containing acrylic rubber HTR-860P-3 made by Use) 150 parts by weight, 0.5 part by weight of a curing accelerator 1-cyanoethyl-2-phenylimidazole (Cureazole 2PZ-CN) as a hardening accelerator, γ-glycidoxypropyltrimethoxysilane (Nihon Unicar) as a silane coupling agent NUC A-187 manufactured by Co., Ltd. was used) Methyl ethyl ketone was added to a composition consisting of 0.7 parts by weight, stirred and mixed, and vacuum degassed. The obtained varnish was coated on a 75 μm thick release-treated polyethylene terephthalate film and dried by heating at 140 ° C. for 5 minutes to form a B-stage coating film having a thickness of 80 μm to produce an adhesive film did.
[0134]
The degree of cure of the adhesive in this state was measured using DSC (912 type DSC manufactured by DuPont) (temperature increase rate, 10 ° C./min), and as a result, the heat generation of 15% of the total heating value was finished. It was in a state. Also, after immersing the adhesive (weight W1) in THF and leaving it to stand at 25 ° C. for 20 hours, the undissolved portion was filtered with a 200 mesh nylon cloth, and the weight after drying this was measured (weight W2). The THF extraction rate (= (W1-W2) × 100 / W1) was determined, and the THF extraction rate was 35% by weight. Further, the storage elastic modulus of the cured adhesive was measured using a dynamic viscoelasticity measuring device (DVE-V4, manufactured by Rheology) (sample size: length 20 mm, width 4 mm, film thickness 80 μm, heating rate 5 ° C./min. , Tensile mode automatic static load), the result was 360 MPa at 25 ° C. and 4 MPa at 260 ° C.
<Example 4>
The phenoxy resin used in Example 3 was changed to carboxyl group-containing acrylonitrile butadiene rubber (with a molecular weight of 400,000, using PNR-1 manufactured by Nippon Synthetic Rubber Co., Ltd.), and an adhesive film was prepared in the same manner as in Example 1. did. Note that the degree of cure of the adhesive in this state was measured using DSC, and as a result, the heat generation of 20% of the total curing heat generation amount was finished. The THF extraction rate was 35% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring device, it was 300 MPa at 25 ° C. and 3 MPa at 260 ° C.
<Example 5>
10 parts by volume of silica was added to 100 parts by volume of the adhesive solid content of the adhesive varnish of Example 3, and an adhesive film was prepared in the same manner as Example 1 using a varnish kneaded for 60 minutes by a bead mill. As a result of measurement using DSC, the heat generation of 15% of the total curing heat generation amount was completed. The THF extraction rate was 30% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring device, it was 1,500 MPa at 25 ° C. and 10 MPa at 260 ° C.
<Example 6>
An adhesive film was produced in the same manner as in Example 1 except that the phenoxy resin used in Example 3 was not used. As a result of measurement using DSC, the heat generation of 15% of the total curing heat generation amount was completed. The THF extraction rate was 35% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring apparatus, it was 350 MPa at 25 ° C. and 4 MPa at 260 ° C.
<Comparative Example 6>
An adhesive film was produced in the same manner as in Example 1 except that the amount of the epoxy group-containing acrylic rubber in Example 3 was changed from 150 parts by weight to 50 parts by weight. As a result of measurement using DSC, the heat generation of 20% of the total heat generation amount was finished. The THF extraction rate was 40% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring device, it was 3,000 MPa at 25 ° C. and 5 MPa at 260 ° C.
<Comparative Example 7>
An adhesive film was produced in the same manner as in Example 1 except that the amount of the epoxy group-containing acrylic rubber in Example 3 was changed from 150 parts by weight to 400 parts by weight. As a result of measurement using DSC, the heat generation of 20% of the total heat generation amount was finished. The THF extraction rate was 30% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring device, it was 200 MPa at 25 ° C. and 1 MPa at 260 ° C.
<Comparative Example 8>
An adhesive film was produced in the same manner as in Example 1 except that 150 parts by weight of the epoxy group-containing acrylic rubber of Example 3 was changed to phenoxy resin (160 parts by weight of phenoxy resin). The total curing exotherm of this adhesive film was 20%, and the THF extraction rate was 90% by weight. The storage elastic modulus was 3,400 MPa at 25 ° C. and 3 MPa at 260 ° C.
<Comparative Example 9>
An adhesive film was produced in the same manner as in Example 1 except that the epoxy group-containing acrylic rubber in Example 3 was changed to acrylonitrile butadiene rubber. The total curing heat value of this adhesive film was 20%, and the THF extraction rate was 90% by weight. The storage elastic modulus was 500 MPa at 25 ° C. and 2 MPa at 260 ° C.
About the semiconductor device produced using the obtained adhesive film, heat resistance, electric corrosion resistance, and moisture resistance were investigated. The evaluation method of heat resistance includes reflow crack resistance of a semiconductor device sample (a solder ball is formed on one side) of a semiconductor chip and a flexible printed wiring board using a polyimide film having a thickness of 25 μm as a base material. A temperature cycle test was applied. Evaluation of reflow crack resistance is a process of cooling the sample by passing it through an IR (infrared) reflow oven set at a maximum temperature of 240 ° C. and holding this temperature for 20 seconds and leaving it at room temperature. This was performed by observing cracks in the sample repeated twice. The thing which did not generate | occur | produce a crack was made good, and the thing which had generate | occur | produced was made into the defect. The temperature cycle test showed the number of cycles until destruction occurred, with the process of leaving the sample in a −55 ° C. atmosphere for 30 minutes and then leaving the sample in a 125 ° C. atmosphere for 30 minutes as one cycle. In addition, evaluation of electric corrosion resistance was made by forming a sample in which a comb pattern of line / space = 75/75 μm was formed on an FR-4 substrate, and an adhesive film was bonded thereon, and 85 ° C./85% RH / The measurement was performed by measuring the insulation resistance value after 1,000 hours under the condition of DC6V application. Those having an insulation resistance value of 10Ω or more were considered good, and those having an insulation resistance value of less than 10Ω were considered bad. Further, the moisture resistance evaluation was performed by observing the peeling and discoloration of the adhesive film after the semiconductor device sample was treated in a pressure cooker tester for 96 hours (PCT treatment). Those in which peeling or discoloration of the adhesive film was not observed were regarded as good, and those in which peeling or discoloration was observed were regarded as defective. The results are shown in Table 2.

[0135]
Examples 3, 4 and 5 are all adhesives including an epoxy resin and its curing agent, a high molecular weight resin compatible with the epoxy resin, an epoxy group-containing acrylic copolymer, and a curing accelerator. Example 6 is an adhesive containing both an epoxy resin and its curing agent, an epoxy group-containing acrylic copolymer, and a curing accelerator, and shows the storage elastic modulus at 25 ° C. and 260 ° C. defined in the present invention. . These had good reflow crack resistance, temperature cycle test, electric corrosion resistance, and PCT resistance.
[0136]
In Comparative Example 6, since the amount of the epoxy group-containing acrylic copolymer defined in the present invention is small, the storage elastic modulus is high and the stress cannot be relieved, and the reflow crack resistance and the result in the temperature cycle test are poor and the reliability is low. Inferior. In Comparative Example 7, the amount of the epoxy group-containing acrylic copolymer defined in the present invention is too large and the storage elastic modulus is low and good, but the handleability of the adhesive film is poor. Comparative Example 8 is a composition that does not contain the epoxy group-containing acrylic copolymer defined in the present invention, so the storage elastic modulus is high, and as in Comparative Example 1, the stress cannot be relaxed and the reflow crack resistance, temperature cycle test The result at is bad. Comparative Example 9 did not contain the epoxy group-containing acrylic copolymer defined in the present invention, contained other rubber components, and had a low storage elastic modulus at 25 ° C., but showed a poor electrical corrosion resistance.
<Example 7>
As epoxy resin, 45 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 200, using Epicoat 828 manufactured by Yuka Shell Epoxy Co., Ltd.), cresol novolac type epoxy resin (epoxy equivalent 220, product name manufactured by Sumitomo Chemical Co., Ltd.) 15 parts by weight, 40 parts by weight of phenol novolak resin (using Dainippon Ink Chemical Co., Ltd., priofen LF2882) as a curing agent for epoxy resin, compatible with epoxy resin and weight average Phenoxy resin as a high molecular weight resin having a molecular weight of 30,000 or more (with a molecular weight of 50,000, using phenototo YP-50 manufactured by Toto Kasei Co., Ltd.), epoxy group-containing acrylic as an epoxy group-containing acrylic copolymer Rubber (Molecular weight 1 million, Teikoku Chemical Industry Co., Ltd. 150 parts by weight of HTR-860P-3 manufactured by the company), 0.5 part by weight of curing accelerator 1-cyanoethyl-2-phenylimidazole (Cureazole 2PZ-CN) as a curing accelerator, and γ as a silane coupling agent -Glycidoxypropyltrimethoxysilane (using the product name NUC A-187 manufactured by Nippon Unicar Co., Ltd.) To a composition comprising 0.7 parts by weight, methyl ethyl ketone was added, mixed with stirring, and vacuum degassed. The obtained varnish was applied on a polyimide film having a thickness of 50 μm, and dried by heating at 130 ° C. for 5 minutes to form a B-stage coating film having a thickness of 50 μm. Produced. Next, the same varnish is applied to the surface of the single-sided adhesive film on which the polyimide film adhesive is not applied, and heated and dried at 140 ° C. for 5 minutes to form a B-stage coating film having a thickness of 50 μm. A double-sided adhesive film having a three-layer structure was produced.
[0137]
The degree of cure of the adhesive component of the adhesive film in this state was measured using DSC (trade name 912 type DSC manufactured by DuPont) (temperature increase rate, 10 ° C./min). % Heat generation was completed. Also, after immersing the adhesive (weight W1) in THF and leaving it to stand at 25 ° C. for 20 hours, the undissolved portion was filtered with a 200 mesh nylon cloth, and the weight after drying this was measured (weight W2). The THF extraction rate (= (W1-W2) × 100 / W1) was determined, and the THF extraction rate was 35% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring device, it was 360 MPa at 25 ° C. and 4 MPa at 260 ° C.
<Example 8>
The phenoxy resin used in Example 7 was changed to carboxyl group-containing acrylonitrile butadiene rubber (with a molecular weight of 400,000, using PNR-1 manufactured by Nippon Synthetic Rubber Co., Ltd.). A double-sided adhesive film of structure was prepared. In this state, the degree of cure of the adhesive component of the adhesive film was measured using DSC, and as a result, the heat generation of 20% of the total curing heat generation amount was finished. The THF extraction rate was 35% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring device, it was 300 MPa at 25 ° C. and 3 MPa at 260 ° C.
<Example 9>
The adhesive varnish used in Example 7 was applied on a polyethylene terephthalate film having a thickness of 50 μm and dried by heating at 140 ° C. for 5 minutes to form a B-stage coating film having a thickness of 50 μm. An adhesive film for bonding to the resulting heat resistant thermoplastic film was prepared. This adhesive film is laminated on both sides of a 50 μm thick plasma-treated polyimide film using a laminator with a laminator roll temperature of 80 ° C., a feed rate of 0.2 m / min, and a linear pressure of 5 kg. A double-sided adhesive film having a layer structure was produced. In this state, the degree of cure of the adhesive component of the adhesive film was measured using DSC, and as a result, heat generation of 20% of the total curing heat generation amount was finished. The THF extraction rate was 35% by weight. Furthermore, as a result of measuring the storage elastic modulus of the cured adhesive using a dynamic viscoelasticity measuring device, it was 360 MPa at 25 ° C. and 4 MPa at 260 ° C.
<Comparative Example 10>
The adhesive varnish used in Example 7 was applied on a polyethylene terephthalate film having a thickness of 50 μm, and dried by heating at 140 ° C. for 5 minutes to form a B-stage coating film having a thickness of 75 μm. Produced. Two adhesive films were used and bonded together under the same lamination conditions as in Example 3 to produce an adhesive film that did not use a core material. The total curing exotherm of the adhesive component of the obtained adhesive film was 20%, and the THF extraction rate was 35% by weight. Moreover, the storage elastic modulus was 360 MPa at 25 ° C. and 4 MPa at 260 ° C.
<Comparative Example 11>
A double-sided adhesive film having a three-layer structure was produced in the same manner as in Example 1 except that the polyimide film used as the heat-resistant thermoplastic film serving as the core material of Example 7 was changed to a polypropylene film. The total curing exotherm of the adhesive component of this adhesive film was 20%, and the THF extraction rate was 35% by weight. Moreover, the storage elastic modulus was 360 MPa at 25 ° C. and 4 MPa at 260 ° C.
<Comparative Example 12>
A double-sided adhesive film having a three-layer structure was prepared in the same manner as in Example 1 except that the epoxy group-containing acrylic copolymer of Example 7 was changed to phenoxy resin (165 parts by weight of phenoxy resin). The total curing heat value of the adhesive component of this adhesive film was 20%, and the THF extraction rate was 90% by weight. The storage elastic modulus was 3,400 MPa at 25 ° C. and 3 MPa at 260 ° C.
<Comparative Example 13>
A double-sided adhesive film having a three-layer structure was produced in the same manner as in Example 1 except that the epoxy group-containing acrylic copolymer of Example 7 was changed to acrylonitrile butadiene rubber. The total curing heat value of this adhesive film adhesive component was 20%, and the THF extraction rate was 90% by weight. The storage elastic modulus was 500 MPa at 25 ° C. and 2 MPa at 260 ° C.
[0138]
About the obtained adhesive film, heat resistance, electric corrosion resistance, and moisture resistance were investigated. As a heat resistance evaluation method, a reflow crack resistance sample and a temperature cycle test were applied to a sample in which a semiconductor chip and a printed wiring board were bonded with a double-sided adhesive film having a three-layer structure. Evaluation of reflow cracking resistance was repeated twice by passing the sample through an IR reflow furnace set at a maximum temperature of 240 ° C and holding the temperature for 20 seconds, and allowing it to cool at room temperature. This was done by observing cracks in the sample. The thing which did not generate | occur | produce a crack was made good, and the thing which had generate | occur | produced was made into the defect. The temperature cycle test showed the number of cycles until destruction occurred, with the process of leaving the sample in a −55 ° C. atmosphere for 30 minutes and then leaving the sample in a 125 ° C. atmosphere for 30 minutes as one cycle. In addition, the evaluation of electric corrosion resistance was made by forming a comb / pattern with a line / space = 75/75 μm on the FR-4 substrate and bonding an adhesive film thereon to produce a sample at 85 ° C./85% RH / DC6V. The measurement was performed by measuring the insulation resistance value after 1,000 hours under the applied conditions. Those having an insulation resistance value of 10Ω or more were considered good, and those having an insulation resistance value of less than 10Ω were considered bad. Moreover, the moisture resistance evaluation was performed by observing the peeling and discoloration of the adhesive film after the heat resistance evaluation sample was treated for 96 hours (PCT treatment) in a pressure cooker tester. Those in which peeling or discoloration of the adhesive film was not observed were regarded as good, and those in which peeling or discoloration was observed were regarded as defective. The results are shown in Table 3.

[0139]
Examples 7, 8, and 9 are all double-sided adhesive films having a three-layer structure using a heat-resistant thermoplastic film as the core material, and the adhesive component is compatible with an epoxy resin, its curing agent, and epoxy resin. Since both the high molecular weight resin and the epoxy group-containing acrylic copolymer are included, the storage elastic modulus at 25 ° C. and 260 ° C. defined in the present invention is shown. These were excellent in handleability and had good reflow crack resistance, temperature cycle test, electric corrosion resistance, and PCT resistance.
[0140]
Since Comparative Example 10 was not a double-sided adhesive film having a three-layer structure in which a heat-resistant thermoplastic film was used as the core material defined in the present invention, the handling property was inferior. Since the comparative example 11 used the polypropylene film inferior to heat resistance for a core material, it was inferior to the reflow resistance and the temperature cycle test result. Since Comparative Example 12 was a composition that did not contain the epoxy group-containing acrylic copolymer specified in the present invention, it showed a high value exceeding the storage elastic modulus at 25 ° C. specified, and resistance to reflow cracking And it was inferior to the temperature cycle test result. Since Comparative Example 13 was matched with the storage elastic modulus at 25 ° C. specified without including the epoxy group-containing acrylic rubber specified in the present invention, the results showed inferior electrical corrosion resistance and PCT resistance.
(Industrial applicability)
According to the present invention, it is possible to manufacture a semiconductor package having excellent moisture absorption reflow resistance and excellent temperature cycle resistance when mounted on a mother board.
[0141]
Since the adhesive and adhesive film of the present invention have a low elastic modulus near room temperature, thermal expansion when a semiconductor chip is mounted on a rigid printed wiring board and a flexible printed wiring board represented by a glass epoxy board or a polyimide board. The thermal stress during heating / cooling caused by the difference in coefficients can be relaxed. Therefore, the generation of cracks during reflow is not recognized, and the heat resistance is excellent. In addition, it contains an epoxy group-containing acrylic copolymer as a low elastic modulus component, and has excellent characteristics with little deterioration when subjected to a moisture resistance test under severe conditions such as electric corrosion resistance and moisture resistance, especially PCT treatment. Material can be provided.
[0142]
The double-sided adhesive film having a three-layer structure using a heat-resistant thermoplastic film as the core material of the present invention is excellent in handleability even though the elastic modulus of the adhesive layer near room temperature is low, and is a glass epoxy substrate In addition, the thermal stress during heating and cooling caused by the difference in thermal expansion coefficient when a semiconductor chip is mounted on a rigid printed wiring board represented by a polyimide substrate and a flexible printed wiring board can be reduced. Therefore, the generation of cracks during reflow is not recognized, and the heat resistance is excellent. In addition, it contains an epoxy group-containing acrylic copolymer as a low elastic modulus component, and has excellent characteristics with little deterioration when subjected to a moisture resistance test under severe conditions such as electric corrosion resistance and moisture resistance, especially PCT treatment. Material can be provided.
[0143]
The semiconductor package of the present invention in which the external terminals are arranged in an area array on the back surface of the substrate is particularly suitable for being mounted on a portable device or a small electronic device for PDA.
[Brief description of the drawings]
FIG. 1 (a) is a cross-sectional view of a single layer thermosetting adhesive film according to the present invention, and FIG. 1 (b) is a cross-sectional view of a three-layer adhesive film according to the present invention.
FIG. 2 is a cross-sectional view of a semiconductor mounting substrate in which an adhesive member is thermocompression bonded to an organic wiring substrate.
FIG. 3 is a cross-sectional view of a semiconductor mounting substrate obtained by thermocompression bonding an adhesive member to an organic wiring substrate.
FIG. 4 is a cross-sectional view of the semiconductor device of the present invention.
FIG. 5 is a cross-sectional view of another example of the semiconductor device of the present invention.
FIG. 6 is a cross-sectional view showing a manufacturing process of an embodiment of a semiconductor mounting substrate and a semiconductor device.
FIG. 7 is a cross-sectional view showing a manufacturing process of another embodiment of the semiconductor mounting substrate and the semiconductor device.
FIG. 8 is a cross-sectional view of another example of the semiconductor device of the present invention.

Claims (14)

An adhesive film for mounting a semiconductor element on a substrate,
A base film, and an adhesive layer formed on the base film,
The adhesive layer is made of a thermosetting resin containing an epoxy group-containing acrylic copolymer and an epoxy resin,
The adhesive layer has a storage elastic modulus of 10 to 2000 MPa at 25 ° C. and 3 to 50 MPa at 260 ° C. when measured using a dynamic viscoelasticity measuring device,
The adhesive cured product is in a state in which heat generation of 95 to 100% of the total curing calorific value when measured using a differential calorimeter is finished,
The storage elastic modulus was measured in a temperature-dependent measurement mode in which a tensile load was applied to the cured adhesive and the frequency was measured from −50 ° C. to 300 ° C. at a temperature rising rate of 5-10 ° C./min. An adhesive film characterized by being. The base film is selected from a polytetrafluoroethylene film, a polyethylene terephthalate film, a release-treated polyethylene terephthalate film, a polyethylene film, a polypropylene film, a polymethylpentene film, and a polyimide film. Adhesive film. The adhesive film according to claim 1, wherein the adhesive layer contains an epoxy resin curing agent. The epoxy resin curing agent is selected from the group consisting of amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, and compounds having two or more phenolic hydroxyl groups in one molecule. Adhesive film. The adhesive film according to claim 1, wherein the adhesive layer contains an epoxy resin curing accelerator. The adhesive film according to claim 1, wherein the adhesive layer contains imidazoles. The imidazole is a compound selected from 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-cyanoethyl-2-phenylimidazolium trimellitate. The adhesive film according to claim 6. The adhesive film according to claim 2, wherein the epoxy group-containing acrylic copolymer has a glass transition temperature of -10 ° C or higher. The adhesive film according to claim 2, wherein the epoxy group-containing acrylic copolymer is an acrylic copolymer containing 2 to 6% by weight of glycidyl (meth) acrylate. The adhesive film according to claim 2, wherein the epoxy group-containing acrylic copolymer has a weight average molecular weight of 800,000 or more. The adhesive film according to claim 1, wherein the amount of residual solvent contained in the adhesive layer is 5 wt% or less. The adhesive layer is 10 to 40% of the total calorific value when measured with a differential calorimeter. The adhesive film according to claim 1, wherein the adhesive film is in a state in which heat is finished. The adhesive film according to claim 1, wherein the adhesive layer contains a silane coupling agent. The adhesive layer has a THF extraction rate of 80% by weight or less,
The THF extraction rate was determined by immersing the adhesive layer having a weight W1 in tetrahydrofuran and allowing it to stand at 25 ° C. for 20 hours, and then filtering the undissolved portion with a 200-mesh nylon cloth and drying it to measure the weight W2. The adhesive film according to claim 1, which is a value calculated by the following mathematical formula (2).

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