JP4145438B2 - Epoxy resin composition and semiconductor device - Google Patents

Description

（式中のＲ₁、Ｒ₂は、炭素数１〜４のアルキル基の中から選択される同一もしくは異なる基、ａは０〜３の整数、ｂは０〜４の整数、ｍは平均値で、ｍ＝１〜１０の正数）
【０００６】
【化５】

（式中のＲ₁、Ｒ₂は、炭素数１〜４のアルキル基の中から選択される同一もしくは異なる基、ａは０〜３の整数、ｂは０〜４の整数、ｍ、ｎは平均値で、いずれもｍ、ｎ＝１〜１０の正数）
【０００７】
【発明の実施の形態】
以下に本発明を詳細に説明する。
本発明に用いられる一般式（１）のエポキシ樹脂は、エポキシ基間に疎水性構造を有しており、フェノール樹脂と組み合わせた樹脂組成物の硬化物は、架橋密度が低く、かつ疎水性の構造が多いことから吸湿率が低く、樹脂組成物の成形時の熱応力或いは成形品である半導体装置の吸湿後の半田処理での発生熱応力を低減し、更にリードフレーム等の基材との密着性にも優れている。一方、エポキシ基間の疎水性構造は、剛直なビフェニル骨格であることから、架橋密度が低いにもかかわらず、耐熱性の低下が少ないという特徴を有している。
一般式（１）のエポキシ樹脂の内では、硬化性の点で優れていることから式（４）の構造の樹脂が好ましい。
【化６】

【０００８】
本発明で用いられる一般式（１）のエポキシ樹脂は、１５０℃でのＩＣＩ粘度計（コーン＆プレート型）での溶融粘度が０．１〜２．５ポイズであり、特に０．１〜０．８ポイズがより好ましい。無機充填材の配合量を全エポキシ樹脂組成物に対して７５〜９５重量％にする場合、２．５ポイズを越えると溶融時の流動性が著しく低下するので好ましくない。
本発明に用いられるエポキシ樹脂は、その特性が損なわれない範囲で他のエポキシ樹脂と併用してもかまわないが、このエポキシ樹脂の配合量を調節することにより、耐半田クラック性を最大限に引き出すことができる。耐半田クラック性の効果を引き出すためには、一般式（１）で示されるエポキシ樹脂を全エポキシ樹脂量に対して３０重量％以上、好ましくは５０重量％以上の使用が望ましい。３０重量％未満だと高温時の低弾性化及び接着性が十分に得られず、耐半田クラック性が不十分となるおそれがある。
【０００９】
併用する場合のエポキシ樹脂としては、エポキシ基を有するモノマー、オリゴマー、ポリマー全般を指し、例えば、ビフェニル型エポキシ樹脂、スチルベン型エポキシ樹脂、ハイドロキノン型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂等の結晶性エポキシ樹脂、ビスフェノールＡ型エポキシ樹脂、オルソクレゾールノボラック型エポキシ樹脂、ジシクロペンタジエン変性フェノール型エポキシ樹脂、トリフェノールメタン型エポキシ樹脂、ナフトール型エポキシ樹脂等が挙げられる。又、これらのエポキシ樹脂は、単独もしくは混合して用いても差し支えない。特にエポキシ樹脂組成物の無機充填材の充填量を高めるためには、室温では結晶性を示し、成形温度においては溶融粘度が極めて低下する結晶性エポキシ樹脂が好ましい。
【００１０】
本発明に用いられる一般式（２）で示されるフェノール樹脂は、例えばビス（メトキシメチル）ビフェニル及びビス（メトキシメチル）ベンゼンとフェノール類をフリーデル・クラフツ・アルキル化反応により重合させて得られる。
一般式（２）で示されるフェノール樹脂を用いた樹脂組成物の硬化物は、ガラス転移温度を越えた高温域での弾性率が低く、低吸湿性であるため表面実装の半田付け時における熱ストレスを低減させることができ耐半田クラック性、半田処理後の基材との密着性に優れた特徴を有している。この樹脂は、一般式（５）のジフェニレン骨格のみを含むフェノールアラルキル樹脂に比べ、樹脂組成物の硬化性が向上し成形性に優れている。又、一般式（６）のフェニレン骨格のみを含むフェノールアラルキル樹脂に比べ、樹脂組成物の硬化物は低吸湿性、熱時低弾性の特徴を有し、接着強度、耐湿信頼性に優れている。又、一般式（５）のジフェニレン骨格を含むフェノールアラルキル樹脂と一般式（６）のフェニレン骨格を含むフェノールアラルキル樹脂を単に混合した場合は、硬化性の高い一般式（６）のフェノールアラルキル樹脂が硬化網目構造を先に形成し、硬化性の低い一般式（５）のフェノールアラルキル樹脂が硬化時に取り残されるため、成形品表面と金型との界面に一般式（５）のフェノールアラルキル樹脂がブリードし、金型や成形品表面に汚れを発生したり、硬化網目構造が不均一なため曲げ強度等の機械的特性が低下する。これに対し１分子中にジフェニレン構造とフェニレン構造の両者を有する一般式（２）で示されるフェノール樹脂は、両方の樹脂の特徴をバランス良く有しており、均一な硬化挙動と均一な硬化物構造を形成する。
【化７】

【００１１】
【化８】

一般式（２）中のＲ₁、Ｒ₂は、炭素数１〜４のアルキル基の中から選択される同一もしくは異なる基、ａは０〜３の整数、ｂは０〜４の整数、ｍ、ｎは平均値で、いずれもｍ、ｎ＝１〜１０の正数である。いずれかかが１０を越えると流動性が劣り好ましくない。より好ましいｍ、ｎは１〜５である。
ｍとｎの合計に対するｍの割合は、０．１〜０．９が好ましい。０．１未満だと高温時の弾性率の低下が小さくなり、硬化性が悪く、０．９を越えると硬化性が悪くなる傾向にある。更に、一般式（２）の内では、硬化性、流動性、高温時の弾性率等のバランスから式（３）で示される樹脂が好ましい。
【００１２】
【化９】

一般式（２）で示されるフェノール樹脂の１５０℃での溶融粘度としては、０．１〜１．５ポイズが好ましい。１．５ポイズを越えると、溶融時の流動性が低下することになる。本発明のフェノール樹脂の１５０℃での溶融粘度は、前記のエポキシ樹脂と同様にＩＣＩ粘度計（コーン＆プレート型）を用いて測定したものである。
一般式（２）で示されるフェノール樹脂は、その特性が損なわれない範囲で他のフェノール樹脂と併用してもかまわないが、このフェノール樹脂の配合量を調節することにより、耐半田クラック性を最大限に引き出すことができる。耐半田クラック性の効果を引き出すためには、一般式（２）で示されるフェノール樹脂を全フェノール樹脂量に対して３０重量％以上、好ましくは５０重量％以上の使用が望ましい。３０重量％未満だと高温時の低弾性化及び接着性が十分に得られず、耐半田クラック性が不十分となるおそれがある。
【００１３】
併用するフェノール樹脂としては、分子内にフェノール性水酸基を有するモノマー、オリゴマー、ポリマー全般を指し、例えば、フェノールノボラック樹脂、クレゾールノボラック樹脂、テルペン変性フェノール樹脂、ジシクロペンタジエン変性フェノール樹脂、トリフェノールメタン型樹脂等が挙げられる。又、これらのフェノール樹脂は、単独もしくは混合して用いても差し支えない。
本発明に用いられる一般式（１）で示されるエポキシ樹脂、および一般式（２）で示されるフェノール樹脂は、ビフェニル誘導体のような芳香族環が含まれることにより分子間の結合エネルギーが大きくなり、燃焼による分解が起こりにくくなり難燃性が発現する。エポキシ樹脂或いはフェノール樹脂の分子中に芳香族環数は多い方が燃えにくくなり難燃性は向上するが、軟化点が高くなり過ぎ流動性の問題があるためビフェニル誘導体が、難燃性と流動性のバランスの点から優れており最適である。
【００１４】
本発明に用いられる無機充填材の種類については特に制限はなく、一般に封止材料に用いられている無機充填材を使用することができる。例えば、溶融破砕シリカ、溶融球状シリカ、結晶シリカ、２次凝集シリカ、アルミナ、チタンホワイト、水酸化アルミニウム、タルク、クレー、ガラス繊維等が挙げられ、特に溶融球状シリカ粉末が好ましい。形状は限りなく真球状であることが好ましく、又、粒子の大きさの異なるものを混合することにより充填量を多くすることができる。
この無機充填材の配合量としては、全エポキシ樹脂組成物中７５〜９５重量％が好ましく、７５重量％未満だと樹脂組成物の硬化物の吸湿量が増大し、かつ半田処理温度での強度が低下してしまうため、半田処理時に半導体装置にクラックが発生し易くなるおそれがあり好ましくない。一方、９５重量％を越えると、樹脂組成物の成形時の流動性が低下し、未充填やチップシフト、パッドシフトが発生し易くなり好ましくない。
又、難燃剤としてハロゲン系難燃剤及び三酸化アンチモンを配合しないエポキシ樹脂組成物の場合、無機充填材の量は、８６重量％以上とすることが好ましい。８６重量％未満では燃焼するおそれがあり好ましくない。
本発明に用いられる無機充填材は、予め充分混合しておくことが好ましい。又、必要に応じて無機充填材をカップリング剤や樹脂で予め処理して用いても良く、処理の方法としては、溶剤を用いて混合した後に溶媒を除去する方法や、直接無機充填材に添加し混合機を用いて処理する方法等がある。
【００１５】
本発明に用いられる硬化促進剤としては、エポキシ樹脂とフェノール樹脂との架橋反応の触媒となり得るものを指し、例えば、１，８−ジアザビシクロ（５，４，０）ウンデセン−７等のアミジン系化合物、トリフェニルホスフィン、テトラフェニルホスフォニウム・テトラフェニルボレート塩等の有機リン化合物、２−メチルイミダゾール等のイミダゾール化合物が挙げられる。これらの硬化促進剤は単独であっても併用しても良い。
【００１６】
本発明の樹脂組成物は、（Ａ）〜（Ｄ）成分の他、必要に応じて臭素化エポキシ樹脂、三酸化アンチモン等の難燃剤、シリコーンオイル、シリコーンゴム等の低応力成分、γ-グリシドキシプロピルトリメトキシシラン等のカップリング剤、カーボンブラック等の着色剤、天然ワックス、合成ワックス、高級脂肪酸及びその金属塩類もしくはパラフィン等の離型剤、酸化防止剤等の各種添加剤が適宜配合可能である。
本発明の樹脂組成物は、（Ａ）〜（Ｄ）成分、及びその他の添加剤等を、ミキサー等を用いて混合後、加熱ニーダや熱ロールを用いて加熱混練し、続いて冷却、粉砕することで得られる。
本発明の樹脂組成物を用いて、半導体素子等の電子部品を封止し、半導体装置を製造するには、トランスファーモールド、コンプレッションモールド、インジェクションモールド等の従来の成形方法で硬化成形すればよい。
【００１７】
以下に本発明の実施例を示すが、本発明はこれらに限定されるものではない。配合単位は重量部とする。

をミキサーを用いて混合した後、表面温度が９０℃と４５℃の２本ロールを用いて３０回混練し、得られた混練物シートを冷却後粉砕して、樹脂組成物を得た。得られた樹脂組成物を以下の方法で評価した。結果を表１に示す。
【００２０】
評価方法
スパイラルフロー：ＥＭＭＩ−１−６６に準じたスパイラルフロー測定用の金型を用いて、金型温度１７５℃、注入圧力７０ｋｇ／ｃｍ²、硬化時間２分で測定した。単位はｃｍ。
耐燃試験：ＵＬ−９４垂直試験（試料厚さ１／１６ｉｎｃｈ）に準じて測定する。
硬化トルク：キュラストメータ（（株）オリエンテック・製、ＪＳＲキュラストメータＩＶＰＳ型）を用い、１７５℃、９０秒後のトルクを求めた。キュラストメータにおけるトルクは硬化性のパラメータであり、数値の大きい方が硬化性が良好である。単位ｋｇｆ−ｃｍ。
熱時弾性率：２４０℃での曲げ弾性率をＪＩＳ Ｋ ６９１１に準じて測定した。単位はｋｇｆ／ｍｍ²。
耐半田クラック性：１００ピンＴＱＦＰ（パッケージサイズは１４×１４ｍｍ、厚み１．４ｍｍ、シリコンチップサイズは８．０×８．０ｍｍ、リードフレームは４２アロイ製）を、金型温度１７５℃、注入圧力７５ｋｇ／ｃｍ²、硬化時間２分でトランスファー成形し、１７５℃、８時間で後硬化させた。得られた半導体パッケージを８５℃、相対湿度８５％の環境下で１６８時間放置し、その後２４０℃の半田槽に１０秒間浸漬した。顕微鏡で外部クラックを観察し、クラック数［（クラック発生パッケージ数）／（全パッケージ数）×１００］を％で表示した。又、チップと樹脂組成物の硬化物との剥離面積の割合を超音波探傷装置を用いて測定し、剥離率［（剥離面積）／（チップ面積）×１００］として、５個のパッケージの平均値を求め、％で表示した。
吸湿率：５０ｍｍφ、２ｍｍ厚の成形円盤を８５℃、相対湿度８５％の環境下に１６８時間放置後の重量増加率により吸湿率を算出した。
【００２１】
実施例２〜５、比較例１〜４
表１に示す割合で各成分を配合し、実施例１と同様にして樹脂組成物を得、実施例１と同様にして評価した。結果を表１に示す。
なお、実施例２〜５、比較例１〜４で用いたエポキシ樹脂の性状を以下に示す。
式（３）のフェノール樹脂（ｍ／ｎ＝７３／２７、水酸基当量１９６、軟化点７２℃、溶融粘度０．８ポイズ／１５０℃）（以下フェノール樹脂Ｂという）、４，４’−ビス（２，３−エポキシプロポキシ）−３，３’，５，５’−テトラメチルビフェニルを主成分とするエポキシ樹脂（エポキシ当量１９１、融点１０５℃）（以下エポキシ樹脂Ａという）、
フェノールノボラック樹脂（水酸基当量１０５、軟化点８５℃））、
式（７）のフェノール樹脂（水酸基当量１９９、軟化点７７℃）、
式（８）のフェノール樹脂（水酸基当量１６５、軟化点６２℃）。
以下に式（７）、式（８）の構造を示す。
【化１０】

【００２２】
【化１１】

【００２３】
【表１】

【００２４】
【発明の効果】
本発明の樹脂組成物を用いると、成形性、難燃性に優れ、かつ封止された半導体装置は熱時の弾性率低下、吸湿性低下により吸湿後の耐半田クラック性に優れる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an epoxy resin composition for semiconductor encapsulation excellent in moldability, solder crack resistance and flame retardancy, and a semiconductor device using the same.
[0002]
[Prior art]
Transfer molding of an epoxy resin composition is employed as a method for sealing semiconductor elements such as IC and LSI at a low cost and suitable for mass production. From the point of view of reliability, the epoxy resin or a phenol resin that is a curing agent is used. Improvements have been made to improve properties. However, due to the recent trend toward smaller, lighter, and higher performance electronic devices, semiconductors have become more highly integrated, and semiconductor devices have become more and more surface mounted. The demand for compositions has become increasingly demanding. For this reason, the problem which cannot be solved with the conventional epoxy resin composition has also come out.
The biggest problem is that, by adopting surface mounting, the semiconductor device is exposed to a high temperature of 200 ° C. or higher suddenly in the solder immersion or reflow process, and the moisture when moisture absorbed absorbs explosively vaporizes the semiconductor device. This is a phenomenon in which cracks are generated, or peeling occurs at the interface between various plated joints on the chip, lead frame, and inner lead and the cured product of the resin composition, resulting in a significant decrease in reliability.
[0003]
In recent years, as the thickness of semiconductor devices has been reduced, the thickness of the resin composition in the semiconductor devices has become even thinner. For example, packages for 64M, 256MDRAM are becoming the mainstream of 1 mm thick TSOP, and are resistant to solder cracks. Sexual demands are getting stronger. In addition, these thin semiconductor devices are required to have a resin composition that has good filling properties during molding, little gold wire deformation, and no chip or lead frame deformation (called chip shift or die pad shift). The resin composition needs to have excellent fluidity during molding.
Furthermore, in the resin sealing composition, a halogen flame retardant and antimony trioxide are often blended as a flame retardant. However, since the halogen-based flame retardant generates halide ions (radicals) at a high temperature, heat resistance such as disconnection of a gold wire is caused. In view of environmental sanitation, a flame retardant sealing material that does not use a halogen-based flame retardant and antimony trioxide is required.
[0004]
[Problems to be solved by the invention]
The present invention provides an epoxy resin composition excellent in moldability, solder crack resistance, and flame retardancy, and a semiconductor device sealed using the same.
[0005]
[Means for Solving the Problems]
That is, the present invention requires (A) an epoxy resin represented by the general formula (1), (B) a phenol resin represented by the general formula (2), (C) an inorganic filler, and (D) a curing accelerator. An epoxy resin composition for encapsulating a semiconductor, characterized by comprising a component, and a semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition.
[Formula 4]

(R ₁ and R ₂ in the formula are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms, a is an integer of 0 to 3, b is an integer of 0 to 4, and m is an average value. And m = 1 to a positive number of 10)
[0006]
[Chemical formula 5]

(R ₁ and R ₂ in the formula are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms, a is an integer of 0 to 3, b is an integer of 0 to 4, m and n are (Average value, both m and n = 1-10 positive numbers)
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The epoxy resin of the general formula (1) used in the present invention has a hydrophobic structure between epoxy groups, and the cured product of the resin composition combined with the phenol resin has a low crosslinking density and is hydrophobic. Since the structure is large, the moisture absorption rate is low, reducing the thermal stress during molding of the resin composition or the thermal stress generated in the solder treatment after moisture absorption of the semiconductor device that is the molded product. Excellent adhesion. On the other hand, since the hydrophobic structure between epoxy groups is a rigid biphenyl skeleton, it has a feature that there is little decrease in heat resistance even though the crosslinking density is low.
Among the epoxy resins of the general formula (1), a resin having a structure of the formula (4) is preferable because of excellent curability.
[Chemical 6]

[0008]
The epoxy resin of the general formula (1) used in the present invention has a melt viscosity of 0.1 to 2.5 poise at 150 ° C. with an ICI viscometer (cone & plate type), particularly 0.1 to 0. .8 poise is more preferred. When the blending amount of the inorganic filler is 75 to 95% by weight based on the total epoxy resin composition, if it exceeds 2.5 poise, the fluidity at the time of melting is remarkably lowered, which is not preferable.
The epoxy resin used in the present invention may be used in combination with other epoxy resins as long as the characteristics are not impaired. However, by adjusting the amount of the epoxy resin, solder crack resistance is maximized. It can be pulled out. In order to bring out the effect of solder crack resistance, the epoxy resin represented by the general formula (1) is desirably used in an amount of 30% by weight or more, preferably 50% by weight or more based on the total amount of the epoxy resin. If it is less than 30% by weight, low elasticity at high temperatures and sufficient adhesion cannot be obtained, and solder crack resistance may be insufficient.
[0009]
When used in combination, the epoxy resin refers to all monomers, oligomers and polymers having an epoxy group, for example, crystalline epoxy resins such as biphenyl type epoxy resins, stilbene type epoxy resins, hydroquinone type epoxy resins, bisphenol F type epoxy resins, etc. Bisphenol A type epoxy resin, orthocresol novolac type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, triphenolmethane type epoxy resin, naphthol type epoxy resin and the like. These epoxy resins may be used alone or in combination. In particular, in order to increase the filling amount of the inorganic filler of the epoxy resin composition, a crystalline epoxy resin that exhibits crystallinity at room temperature and whose melt viscosity is extremely reduced at the molding temperature is preferable.
[0010]
The phenol resin represented by the general formula (2) used in the present invention is obtained, for example, by polymerizing bis (methoxymethyl) biphenyl and bis (methoxymethyl) benzene and phenols by Friedel-Crafts alkylation reaction.
The cured product of the resin composition using the phenol resin represented by the general formula (2) has a low elastic modulus in a high temperature range exceeding the glass transition temperature and low hygroscopicity. Stress can be reduced, and solder crack resistance and excellent adhesion to the substrate after soldering are provided. This resin improves the curability of the resin composition and is excellent in moldability as compared with the phenol aralkyl resin containing only the diphenylene skeleton of the general formula (5). Moreover, compared with the phenol aralkyl resin containing only the phenylene skeleton of the general formula (6), the cured product of the resin composition has characteristics of low hygroscopicity and low elasticity when heated, and is excellent in adhesive strength and moisture resistance reliability. . Moreover, when the phenol aralkyl resin containing the diphenylene skeleton of the general formula (5) and the phenol aralkyl resin containing the phenylene skeleton of the general formula (6) are simply mixed, the phenol aralkyl resin of the general formula (6) having high curability is obtained. Since the cured network structure is formed first and the low-curability phenol aralkyl resin of general formula (5) is left behind during curing, the phenol aralkyl resin of general formula (5) bleeds at the interface between the molded product surface and the mold. However, the surface of the mold or the molded product is soiled, and the cured network structure is not uniform, so that mechanical properties such as bending strength are deteriorated. On the other hand, the phenol resin represented by the general formula (2) having both diphenylene structure and phenylene structure in one molecule has the characteristics of both resins in a well-balanced manner, uniform curing behavior and uniform cured product. Form a structure.
[Chemical 7]

[0011]
[Chemical 8]

R _1, R ₂ in the general formula (2) are the same or different groups selected from among alkyl groups having 1 to 4 carbon atoms, a is an integer of 0 to 3, b is an integer of 0 to 4, m , N are average values, both m and n = 1-10 positive numbers. If either exceeds 10, fluidity is inferior, which is not preferable. More preferable m and n are 1-5.
The ratio of m to the total of m and n is preferably 0.1 to 0.9. If it is less than 0.1, the decrease in elastic modulus at high temperature is small and the curability is poor, and if it exceeds 0.9, the curability tends to be poor. Further, in the general formula (2), the resin represented by the formula (3) is preferable from the balance of curability, fluidity, elastic modulus at high temperature, and the like.
[0012]
[Chemical 9]

The melt viscosity at 150 ° C. of the phenol resin represented by the general formula (2) is preferably 0.1 to 1.5 poise. If it exceeds 1.5 poise, the fluidity at the time of melting will decrease. The melt viscosity at 150 ° C. of the phenol resin of the present invention is measured using an ICI viscometer (cone and plate type) in the same manner as the epoxy resin.
The phenolic resin represented by the general formula (2) may be used in combination with other phenolic resins as long as the characteristics are not impaired. However, by adjusting the amount of the phenolic resin, solder crack resistance can be improved. It can be pulled out to the maximum. In order to bring out the effect of solder crack resistance, the phenol resin represented by the general formula (2) is desirably used in an amount of 30% by weight or more, preferably 50% by weight or more based on the total amount of phenol resin. If it is less than 30% by weight, low elasticity at high temperatures and sufficient adhesion cannot be obtained, and solder crack resistance may be insufficient.
[0013]
The phenol resin to be used in combination refers to monomers, oligomers, and polymers generally having a phenolic hydroxyl group in the molecule. Examples thereof include resins. These phenol resins may be used alone or in combination.
The epoxy resin represented by the general formula (1) and the phenol resin represented by the general formula (2) used in the present invention increase the bond energy between molecules due to the inclusion of an aromatic ring such as a biphenyl derivative. , Decomposition by combustion hardly occurs and flame retardancy is exhibited. The more aromatic rings in the epoxy resin or phenol resin molecule, the more difficult it is to burn and the flame retardancy is improved, but the softening point is too high and there is a problem of fluidity, so the biphenyl derivative has flame retardancy and fluidity. It is excellent in terms of balance of sex and is optimal.
[0014]
There is no restriction | limiting in particular about the kind of inorganic filler used for this invention, The inorganic filler generally used for the sealing material can be used. Examples thereof include fused crushed silica, fused spherical silica, crystalline silica, secondary agglomerated silica, alumina, titanium white, aluminum hydroxide, talc, clay, glass fiber, and the like, and fused spherical silica powder is particularly preferable. The shape is preferably infinitely spherical, and the amount of filling can be increased by mixing particles having different particle sizes.
The blending amount of the inorganic filler is preferably 75 to 95% by weight in the total epoxy resin composition, and if it is less than 75% by weight, the moisture absorption of the cured product of the resin composition is increased and the strength at the soldering treatment temperature is increased. Therefore, there is a possibility that cracks are likely to occur in the semiconductor device during the soldering process, which is not preferable. On the other hand, if it exceeds 95% by weight, the fluidity during molding of the resin composition is lowered, and unfilling, chip shift, and pad shift are likely to occur, which is not preferable.
In the case of an epoxy resin composition that does not contain a halogen-based flame retardant and antimony trioxide as the flame retardant, the amount of the inorganic filler is preferably 86% by weight or more. If it is less than 86% by weight, there is a possibility of burning, which is not preferable.
The inorganic filler used in the present invention is preferably mixed well in advance. In addition, if necessary, the inorganic filler may be pre-treated with a coupling agent or resin, and the treatment method may be a method of removing the solvent after mixing with a solvent, or a direct inorganic filler. There is a method of adding and processing using a mixer.
[0015]
The curing accelerator used in the present invention refers to a compound that can be a catalyst for a crosslinking reaction between an epoxy resin and a phenol resin, for example, an amidine compound such as 1,8-diazabicyclo (5,4,0) undecene-7. Organic phosphorus compounds such as triphenylphosphine and tetraphenylphosphonium tetraphenylborate salts and imidazole compounds such as 2-methylimidazole. These curing accelerators may be used alone or in combination.
[0016]
In addition to the components (A) to (D), the resin composition of the present invention comprises a flame retardant such as brominated epoxy resin and antimony trioxide, a low-stress component such as silicone oil and silicone rubber, γ-glycol as necessary. Various additives such as coupling agents such as sidoxypropyltrimethoxysilane, colorants such as carbon black, natural waxes, synthetic waxes, mold release agents such as higher fatty acids and their metal salts or paraffin, antioxidants, etc. Is possible.
In the resin composition of the present invention, the components (A) to (D), other additives, and the like are mixed using a mixer or the like, then heated and kneaded using a heating kneader or a hot roll, and then cooled and pulverized. It is obtained by doing.
In order to seal an electronic component such as a semiconductor element and manufacture a semiconductor device using the resin composition of the present invention, the resin composition may be cured and molded by a conventional molding method such as transfer molding, compression molding, or injection molding.
[0017]
Examples of the present invention are shown below, but the present invention is not limited thereto. The blending unit is parts by weight.

Were mixed using a mixer, and then kneaded 30 times using two rolls having surface temperatures of 90 ° C. and 45 ° C. The obtained kneaded product sheet was cooled and pulverized to obtain a resin composition. The obtained resin composition was evaluated by the following methods. The results are shown in Table 1.
[0020]
Evaluation Method Spiral Flow: Using a mold for spiral flow measurement according to EMMI-1-66, measurement was performed at a mold temperature of 175 ° C., an injection pressure of 70 kg / cm ² , and a curing time of 2 minutes. The unit is cm.
Flame resistance test: Measured according to UL-94 vertical test (sample thickness 1/16 inch).
Curing torque: Using a curast meter (manufactured by Orientec Co., Ltd., JSR curast meter IVPS type), the torque after 175 ° C. and 90 seconds was determined. The torque in the curast meter is a curability parameter, and the larger the value, the better the curability. Unit kgf-cm.
Elastic modulus at heat: The flexural modulus at 240 ° C. was measured according to JIS K 6911. The unit is kgf / mm ² .
Solder crack resistance: 100-pin TQFP (package size: 14 × 14 mm, thickness: 1.4 mm, silicon chip size: 8.0 × 8.0 mm, lead frame: 42 alloy), mold temperature: 175 ° C., injection pressure Transfer molding was performed at 75 kg / cm ² and a curing time of 2 minutes, and post-curing was performed at 175 ° C. for 8 hours. The obtained semiconductor package was left in an environment of 85 ° C. and relative humidity 85% for 168 hours, and then immersed in a solder bath at 240 ° C. for 10 seconds. External cracks were observed with a microscope, and the number of cracks [(number of crack generating packages) / (total number of packages) × 100] was displayed in%. Further, the ratio of the peeled area between the chip and the cured product of the resin composition was measured using an ultrasonic flaw detector, and the average of five packages was obtained as the peel rate [(peeled area) / (chip area) × 100]. Values were determined and expressed in%.
Moisture absorption rate: The moisture absorption rate was calculated from the weight increase rate after leaving a shaped disk having a diameter of 50 mmφ and a thickness of 2 mm in an environment of 85 ° C. and a relative humidity of 85% for 168 hours.
[0021]
Examples 2-5, Comparative Examples 1-4
Each component was mix | blended in the ratio shown in Table 1, the resin composition was obtained like Example 1, and it evaluated similarly to Example 1. FIG. The results are shown in Table 1.
In addition, the property of the epoxy resin used in Examples 2-5 and Comparative Examples 1-4 is shown below.
Phenol resin of formula (3) (m / n = 73/27, hydroxyl group equivalent 196, softening point 72 ° C., melt viscosity 0.8 poise / 150 ° C.) (hereinafter referred to as phenol resin B), 4,4′-bis ( 2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethylbiphenyl as the main component (epoxy equivalent 191, melting point 105 ° C.) (hereinafter referred to as epoxy resin A),
Phenol novolac resin (hydroxyl equivalent 105, softening point 85 ° C.),
Phenol resin of formula (7) (hydroxyl equivalent 199, softening point 77 ° C.),
Phenol resin of formula (8) (hydroxyl equivalent 165, softening point 62 ° C.).
The structures of formulas (7) and (8) are shown below.
[Chemical Formula 10]

[0022]
Embedded image

[0023]
[Table 1]

[0024]
【The invention's effect】
When the resin composition of the present invention is used, the moldability and flame retardancy are excellent, and the sealed semiconductor device is excellent in solder crack resistance after moisture absorption due to a decrease in elastic modulus and a decrease in moisture absorption during heat.

Claims (5)

(A) An epoxy resin represented by the general formula (1), (B) a phenol resin represented by the general formula (2), (C) an inorganic filler, and (D) a curing accelerator are essential components. An epoxy resin composition for semiconductor encapsulation.

Wherein R ₁ and R ₂ are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms, a is an integer of 0 to 3, b is an integer of 0 to 4, and m is an average value. And m = 1 to a positive number of 10)

Wherein R ₁ and R ₂ are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms, a is an integer of 0 to 3, b is an integer of 0 to 4, m and n are (Average value, both m and n = 1-10 positive numbers) The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phenol resin represented by the general formula (2) is the formula (3).

(M and n are average values, both m and n = 1 to 10 positive numbers) The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, wherein the epoxy resin represented by the general formula (1) has a melt viscosity at 150 ° C of 0.1 to 2.5 poise. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phenol resin represented by the general formula (2) has a melt viscosity at 150 ° C. of 0.1 to 1.5 poise. A semiconductor device comprising a semiconductor element sealed with the epoxy resin composition according to claim 1.