JP4014311B2 - Epoxy resin composition for semiconductor encapsulation and semiconductor device - Google Patents

Description

【０００７】
【化６】

【０００８】
【化７】

（式中、Ｒ³〜Ｒ¹⁰は、それぞれ独立に、水素原子、炭素数１〜６の鎖状もしくは環状アルキル基、又はハロゲンの中から選択される基又は原子を示す。ただし、炭素−炭素二重結合に結合している２個のアリール基は互いに異なる。）
【０００９】
【化８】

（式中、Ｒ¹¹〜Ｒ¹⁴は、それぞれ独立に、水素原子、炭素数１〜６の鎖状もしくは環状アルキル基、又はハロゲンの中から選択される基又は原子を示す。ただし、炭素−炭素二重結合に結合している２個のアリール基は互いに同じである。）
【００１０】
一般式（１）で示されるビフェニル型エポキシ樹脂の置換基Ｒ¹、及び一般式（２）で示されるビスフェノール型エポキシ樹脂の置換基Ｒ²は、水素原子、炭素数１〜６の鎖状もしくは環状アルキル基、フェニル基、又はハロゲンの中から選択される基又は原子であり、互いに同じであっても異なっていてもよく、例えば、メチル基、エチル基、プロピル基、ブチル基、シクロヘキシル基、フェニル基、塩素原子、臭素原子等が挙げられ、特にメチル基が好ましい。
一般式（３）、及び一般式（４）で示されるスチルベン型エポキシ樹脂の置換基Ｒ³〜Ｒ¹⁴は、水素原子、炭素数１〜６の鎖状もしくは環状アルキル基、又はハロゲンの中から選択される基又は原子であり、互いに同一であっても異なっていてもよく、例えば、水素原子、メチル基、エチル基、プロピル基、ブチル基、アミル基、ヘキシル基（各異性体を含む）、シクロヘキシル基、塩素原子、臭素原子等が挙げられ、特に、エポキシ樹脂の溶融粘度の低さから、メチル基、エチル基、プロピル基、又はブチル基が好ましい。
【００１１】
このエポキシ樹脂は、一般式（３）のスチルベン型エポキシ樹脂と一般式（４）のスチルベン型エポキシ樹脂との混合物であり、一般式（３）のスチルベン型エポキシ樹脂、及び一般式（４）のスチルベン型エポキシ樹脂には、共に置換基の種類等により種々の構造のものがあり、一般式（３）及び一般式（４）の各々のスチルベン型エポキシ樹脂は、一種類の構造のものでも、二種類以上の構造のものの混合物でもかまわない。
一般式（３）のスチルベン型エポキシ樹脂と一般式（４）のスチルベン型エポキシ樹脂との混合は、両方の化合物を混合することにより融点が低くなればよく、混合方法については特に限定しない。例えば、スチルベン型エポキシ樹脂の原料であるスチルベン型フェノール類をグリシジルエーテル化する前に混合しておいたり、両方のスチルベン型エポキシ樹脂を溶融混合する方法等があるが、いずれの場合においても融点は５０〜１５０℃となるように調整する。
【００１２】
一般式（３）のスチルベン型エポキシ樹脂としては、入手のし易さ、性能、原料価格の点から、５−ターシャリブチル−４，４’−ジヒドロキシ−２，３’，５’−トリメチルスチルベン、３−ターシャリブチル−４，４’−ジヒドロキシ−３’，５，５’−トリメチルスチルベンのグリシジルエーテル化物が特に好ましい。一般式（４）のスチルベン型エポキシ樹脂としては、性能、原料価格の点から、４，４’−ジヒドロキシ−３，３’，５，５’−テトラメチルスチルベン、４，４’−ジヒドロキシ−３，３’−ジターシャリブチル−６，６’−ジメチルスチルベン、４，４’−ジヒドロキシ−３，３’−ジターシャリブチル−５，５’−ジメチルスチルベンのグリシジルエーテル化物が特に好ましい。
【００１３】
本発明に用いられるフェノール樹脂は、１分子内に２個以上のフェノール性水酸基を有するモノマー、オリゴマー、及びポリマー全般を言う。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、パラキシリレン変性フェノール樹脂、パラキシリレン・メタキシリレン変性フェノール樹脂、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等が挙げられ、これらは単独又は混合して用いてもよい。これらのフェノール樹脂は、分子量、軟化点、水酸基当量等に制限なく使用することができる。
本発明に用いられる全エポキシ樹脂のエポキシ基と全フェノール樹脂のフェノール性水酸基の当量比は、好ましくは０．５〜２、特に好ましくは０．７〜１．５である。０．５〜２の範囲を外れると、硬化性、耐湿性等が低下するので好ましくない。
【００１４】
本発明に用いられる硬化促進剤は、テトラ置換ホスホニウムと１分子内に２個以上のフェノール性水酸基を有する化合物の共役塩基（以下本発明では、１分子内に２個以上のフェノール性水酸基を有する化合物の共役塩基をアニオンと呼ぶ）の塩である。用いる１分子内に２個以上のフェノール性水酸基を有する化合物の抽出水の導電率は、１０００μＳ／ｃｍ以下である必要がある。
本発明での抽出水の導電率の測定方法は、１分子内に２個以上のフェノール性水酸基を有する化合物１ｇを純水（使用する純水の導電率は５μＳ／ｃｍ以下）５０ｇと混合し、プレッシャークッカー容器中で１２５℃、２０時間処理した後、プレッシャークッカー容器の内容物を取り出し、遠心分離して得られる水層の電気伝導度を導電率メーター（（株）堀場製作所・製 ＥＳ−１４型）を用いて常温で測定して得られる値である。
即ち、本発明の硬化促進剤は、テトラ置換ホスホニウムと、抽出水の導電率が１０００μＳ／ｃｍ以下の、１分子内に２個以上のフェノール性水酸基を有する化合物の共役塩基との塩からなるものである。
【００１５】
このような塩としては、例えば、テトラフェニルホスホニウムレゾルシン塩、テトラフェニルホスホニウムビスフェノールＡ塩、テトラフェニルホスホニウムビスフェノールＦ塩、テトラフェニルホスホニウムビスフェノールＳ塩、テトラフェニルホスホニウムビフェノール塩、テトラフェニルホスホニウムジヒドロキシナフタレン塩、テトラフェニルホスホニウムフェノールノボラック樹脂塩、テトラフェニルホスホニウムアラルキル変性フェノール樹脂塩、テトラブチルホスホニウムビスフェノールＡ塩、テトラブチルホスホニウムビスフェノールＦ塩、テトラブチルホスホニウムビスフェノールＳ塩、テトラブチルホスホニウムビフェノール塩、テトラブチルホスホニウムジヒドロキシナフタレン塩、テトラブチルホスホニウムフェノールノボラック樹脂塩、テトラブチルホスホニウムアラルキル変性フェノール樹脂塩、トリフェニルエチルホスホニウムビスフェノールＡ塩、トリトリルメチルホスホニウムビスフェノールＦ塩、トリアニシルエチルホスホニウムビフェノール塩、トリフェニルブチルホスホニウムジヒドロキシナフタレン塩、トリフェニルエチルホスホニウムフェノールノボラック樹脂塩、トリフェニルブチルホスホニウムアラルキル変性フェノール樹脂塩等が例示される。
【００１６】
成分（Ｃ）においては、アニオンの共役酸である１分子内に２個以上のフェノール性水酸基を有する化合物の抽出水の導電率が１０００μＳ／ｃｍ以下であることが、優れた耐湿信頼性を得るための必須条件である。この理由は、プレッシャークッカーバイアステスト（ＰＣＢＴ）では電圧を印加される素子周辺でイオン性不純物に起因する電気泳動現象が起こることがアルミ配線の腐食の原因と考えられるので、前述の抽出水の導電率と耐湿信頼性には相関関係があるのではないかと考えられるからである。又、フェノール性水酸基を有する化合物が１分子内にフェノール性水酸基を２個未満しか有してない場合だと、対応する共役塩基の反応性が低いため硬化の際架橋構造に取り込まれず、遊離した共役塩基が耐湿信頼性や硬化性に影響を与える場合がある。一方、カチオン側のリン原子の置換基は、撥水性があることが好ましく、特にフェニル基が好適である。
以上のことから、成分（Ｃ）のテトラ置換ホスホニウムがテトラフェニルホスホニウムであり、且つ１分子内に２個以上のフェノール性水酸基を有する化合物の共役塩基がレゾルシン、ビスフェノールＡ、ビスフェノールＦ、ビスフェノールＳ、ビフェノール、ジヒドロキシナフタレン、フェノールノボラック樹脂、アラルキル変性フェノール樹脂の共役塩基からなる群より少なくとも１つ選ばれるものが最も好適である。
又、これらの硬化促進剤の特性を損なわない範囲で、トリフェニルホスフィン、１，８−ジアザビシクロ（５，４，０）ウンデセン−７、２−メチルイミダゾール等の他の硬化促進剤と併用しても何ら問題はない。
【００１７】
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ものを使用することができる。例えば、溶融破砕シリカ粉末、溶融球状シリカ粉末、結晶シリカ粉末、２次凝集シリカ粉末、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、全エポキシ樹脂と全フェノール樹脂の合計量１００重量部あたり２００〜２４００重量部が好ましい。２００重量部未満だと、無機充填材による補強効果が充分に発現しないおそれがあり、２４００重量部を越えると、樹脂組成物の流動性が低下し成形時に充填不良等が生じるおそれがあるので好ましくない。特に、無機充填材の配合量が、全エポキシ樹脂と全フェノール樹脂の合計量１００重量部あたり２５０〜１４００重量部であれば、樹脂組成物の硬化物の吸湿率が低くなり、半田クラックの発生を防止することができ、更に溶融時の樹脂組成物の粘度が低くなるため、半導体装置内部の金線変形を引き起こすおそれがなく、より好ましい。又、無機充填材は、予め充分混合しておくことが好ましい。
【００１８】
本発明の樹脂組成物は、（Ａ）〜（Ｄ）成分の他、必要に応じて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、臭素化エポキシ樹脂、酸化アンチモン、リン化合物等の難燃剤、シリコーンオイル、シリコーンゴム等の低応力成分、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を配合することができる。
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を用いて常温混合し、ロール、押出機等の混練機で混練し、冷却後粉砕して得られる。
本発明の樹脂組成物を用いて、半導体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成形方法で硬化成形すればよい。
【００１９】
【実施例】
以下に、実施例を挙げて説明するが、本発明はこれらの実施例によりなんら限定されるものではない。配合割合は重量部とする。
まず、実施例及び比較例で使用した硬化促進剤である化合物１〜６の構造を、まとめて以下に示す。
又、表１に化合物１〜６のフェノール性水酸基を有する化合物の共役塩基に対応する共役酸の名称と、各々の共役酸１ｇを純水５０ｇと混合し、プレッシャークッカー容器中で１２５℃、２０時間処理して得られる抽出水の導電率をまとめて示す。
【００２０】
化合物１
【化９】

【００２１】
化合物２
【化１０】

【００２２】
化合物３
【化１１】

【００２３】
化合物４
【化１２】

【００２４】
化合物５
【化１３】

【００２５】
化合物６
【化１４】

【００２６】
【表１】

【００２７】
実施例１
式（５）のビフェニル型エポキシ樹脂を主成分とする樹脂（エポキシ当量１８５、融点１０５℃） ５１重量部
【化１５】

式（６）のフェノール樹脂（軟化点７３℃） ４９重量部
【００２８】
【化１６】

化合物１ ３．８重量部
溶融球状シリカ（平均粒径１５μｍ） ５００重量部
カーボンブラック ２重量部
臭素化ビスフェノールＡ型エポキシ樹脂 ２重量部
カルナバワックス ２重量部
を混合し、熱ロールを用いて、９５℃で８分間混練して冷却後粉砕し樹脂組成物を得た。得られた樹脂組成物を以下の方法で評価した。結果を表２に示す。
【００２９】
評価方法
スパイラルフロー：ＥＭＭＩ−Ｉ−６６に準じたスパイラルフロー測定用の金型を用い、金型温度１７５℃、注入圧力７０ｋｇ／ｃｍ²、硬化時間２分で測定した。スパイラルフローは流動性のパラメータであり、数値が大きい方が流動性が良好である。単位はｃｍ。
ショアＤ硬度：金型温度１７５℃、注入圧力７０ｋｇ／ｃｍ²、硬化時間２分で成形し、型開き１０秒後に測定したショアＤ硬度の値を硬化性とする。ショアＤ硬度は硬化性の指標であり、数値が大きい方が硬化性が良好である。
耐半田クラック性：金型温度１７５℃、注入圧力７０ｋｇ／ｃｍ²、硬化時間２分で、８０ｐＱＦＰ（厚さ２．０ｍｍ）８個を成形し、８５℃、相対湿度８５％で１６８時間処理した後、２４０℃のＩＲリフローで１０秒間処理しパッケージクラック個数を目視で観察した。クラックの生じたパッケージがｎ個であるとき、ｎ／８と表示する。
３０℃保存性：３０℃で６ヶ月間保存した後、スパイラルフローを測定し、調製直後のスパイラルフローに対する百分率として表す。単位は％。
耐湿信頼性：金型温度１７５℃、圧力７０ｋｇ／ｃｍ²、硬化時間２分で１６ｐＤＩＰを成形した後、１７５℃、８時間で後硬化を行った。１２５℃、相対湿度１００％の水蒸気中で２０Ｖの電圧を印加した後、断線不良を調べた。１５個のパッケージの内の８個以上に不良が出るまでの時間を不良時間とした。単位は時間。なお、測定時間は最長で５００時間とし、その時点で不良パッケージ数が８個未満であったものは、不良時間は５００時間以上と示した。不良時間が長い程、耐湿信頼性に優れる。
【００３０】
実施例２〜８、比較例１〜３
表２、表３の配合に従い、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２、３に示す。
なお、実施例２に使用した結晶性エポキシ樹脂Ａは、４，４’−ビス（２，３−エポキシプロポキシ）−３，３’，５，５’−テトラメチルスチルベンを主成分とする樹脂６０重量％と４，４’−ビス（２，３−エポキシプロポキシ）−５−ターシャリブチル−２，３’，５’−トリメチルスチルベンを主成分とする樹脂４０重量％との混合物である（エポキシ当量２０９、融点１２０℃）。
実施例３に使用したオルソクレゾールノボラック型エポキシ樹脂は、エポキシ当量２００、軟化点６５℃である。
実施例３に使用したフェノールノボラック樹脂は、水酸基当量１０４、軟化点１０５℃である。
比較例１で、硬化促進剤として、対応する共役酸の抽出水の導電率が１０００μＳ／ｃｍを越える化合物６を用いると、耐湿信頼性が低下した。
比較例２で、硬化促進剤としてトリフェニルホスフィンを用いると、耐湿信頼性における不良時間は良好なものの、保存性が低下した。
比較例３で、硬化促進剤として化合物１を用い、無機充填材としての溶融球状シリカ１８０重量部を用いると、無機充填材量が少なく、耐半田クラック性が低下した。
【表２】

【００３１】
【表３】

【００３２】
【発明の効果】
本発明のエポキシ樹脂組成物は、半導体封止用として常温保存特性、及び成形性にきわめて優れ、これを用いた半導体装置は、挿入実装及び表面実装対応の装置として耐湿信頼性に優れ有用である。[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation that is excellent in normal temperature storage characteristics and moisture resistance reliability and is compatible with insertion mounting and surface mounting, and a semiconductor device using the same.
[0002]
[Prior art]
In order to protect the bodies of diodes, transistors, IC chips and the like from mechanical and chemical effects, epoxy resin compositions for semiconductor encapsulation (hereinafter referred to as resin compositions) have been developed and produced. The items required for this resin composition are changing depending on the type of IC chip, the structure of the semiconductor device, and the environment in which it is used. One of the required items is room temperature storage characteristics. In the resin composition, conventionally used curing accelerators include 2-methylimidazole, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, and the like. Since the agent has a curing accelerating action even at a relatively low temperature, the resin composition using these has insufficient room temperature storage characteristics, so when stored at room temperature, poor filling occurs due to a decrease in fluidity during molding, A problem arises in that the gold wire of the IC chip is disconnected and a conduction failure occurs. For this reason, the resin composition needs to be refrigerated and transported refrigerated, and the present situation is that the storage and transport are costly. In recent years, the use conditions of electric and electronic parts have become more severe, and the level of characteristics required for the resin composition, in particular, the humidity resistance reliability has been increasing.
[0003]
[Problems to be solved by the invention]
The present invention relates to an epoxy resin composition for semiconductor encapsulation suitable for insertion mounting and surface mounting excellent in room temperature storage characteristics, moisture resistance reliability, and moldability, and a semiconductor device using the same.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a salt of a specific tetra-substituted phosphonium and a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule is a curing accelerator. As a result, it was found that the epoxy resin composition used as the above exhibits extremely excellent characteristics described above, and the present invention has been completed based on this finding.
That is, the present invention is a salt of (A) an epoxy resin, (B) a phenol resin, (C) a tetrasubstituted phosphonium as a curing accelerator and a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule, In addition, 1 g of a compound having two or more phenolic hydroxyl groups in one molecule is mixed with 50 g of pure water (conductivity of pure water to be used is 5 μS / cm or less) and treated in a pressure cooker container at 125 ° C. for 20 hours. those obtained was extracted water conductivity of not more than 1000 .mu.s / cm, and (D) an inorganic filler as essential components, the equivalent ratio of the phenolic hydroxyl group of the epoxy groups of total epoxy resin total phenolic resin is 0.5 a ~ 2, semi the amount of the inorganic filler (D), characterized in that the total amount from 200 to 2400 parts by weight per 100 parts by weight of the total epoxy resin and the total phenolic resin The present invention relates to an epoxy resin composition for body sealing and a semiconductor device characterized by sealing using the same.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The epoxy resin used in the present invention refers to monomers, oligomers, and polymers in general having two or more epoxy groups in one molecule. For example, biphenyl type epoxy resin, bisphenol type epoxy resin, stilbene type epoxy resin, orthocresol novolac type epoxy resin, phenol novolac type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, triazine nucleus-containing epoxy Examples thereof include resins and dicyclopentadiene-modified phenol type epoxy resins, and these may be used alone or in combination.
Among these epoxy resins, crystalline epoxy resins having a melting point of 50 to 150 ° C. are preferable. Such a crystalline epoxy resin has a rigid structure such as a biphenyl skeleton, a bisphenol skeleton, and a stilbene skeleton in the main chain and is relatively low in molecular weight, and thus exhibits crystallinity. A crystalline epoxy resin is a solid crystallized at room temperature, but rapidly melts into a low-viscosity liquid in a temperature range above the melting point. The melting point of the crystalline epoxy resin indicates the temperature at the top of the endothermic peak of crystal melting, which is heated from room temperature at a heating rate of 5 ° C./min using a differential scanning calorimeter.
[0006]
As the crystalline epoxy resin satisfying these conditions, in particular, one or more selected from the general formula (1) and the general formula (2), or a stilbene type epoxy resin represented by the general formula (3) and the general formula (4) The mixture with the stilbene type epoxy resin shown by these is preferable.
[Chemical formula 5]

[0007]
[Chemical 6]

[0008]
[Chemical 7]

(In the formula, R ^{3 to} R ¹⁰ each independently represents a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon The two aryl groups bonded to the double bond are different from each other.)
[0009]
[Chemical 8]

(In the formula, R ^{11 to} R ¹⁴ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon The two aryl groups bonded to the double bond are the same as each other.)
[0010]
Substituent R ² of the bisphenol type epoxy resin represented by the substituent R ¹ of the biphenyl type epoxy resin represented by the general formula (1), and general formula (2) is a hydrogen atom, a linear or 1 to 6 carbon atoms A group or an atom selected from a cyclic alkyl group, a phenyl group, or a halogen, which may be the same or different from each other, such as a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, A phenyl group, a chlorine atom, a bromine atom, etc. are mentioned, A methyl group is particularly preferable.
The substituents R ^{3 to} R ¹⁴ of the stilbene type epoxy resin represented by the general formula (3) and the general formula (4) are a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms, or halogen. Selected group or atom, which may be the same or different from each other, such as a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a hexyl group (including isomers) , A cyclohexyl group, a chlorine atom, a bromine atom, and the like. In particular, a methyl group, an ethyl group, a propyl group, or a butyl group is preferable because of low melt viscosity of the epoxy resin.
[0011]
This epoxy resin is a mixture of the stilbene type epoxy resin of the general formula (3) and the stilbene type epoxy resin of the general formula (4), and the stilbene type epoxy resin of the general formula (3) and the general formula (4) Both stilbene type epoxy resins have various structures depending on the type of substituents, etc., and each stilbene type epoxy resin of general formula (3) and general formula (4) has a single type of structure, It may be a mixture of two or more structures.
The mixing of the stilbene type epoxy resin of the general formula (3) and the stilbene type epoxy resin of the general formula (4) is not particularly limited as long as the melting point is lowered by mixing both compounds. For example, there are methods such as mixing stilbene type phenols, which are raw materials of stilbene type epoxy resins, before glycidyl etherification, or melting and mixing both stilbene type epoxy resins, but in each case the melting point is It adjusts so that it may become 50-150 degreeC.
[0012]
As the stilbene type epoxy resin of the general formula (3), 5-tertiarybutyl-4,4′-dihydroxy-2,3 ′, 5′-trimethylstilbene is available from the viewpoint of availability, performance and raw material price. 3-tertiarybutyl-4,4′-dihydroxy-3 ′, 5,5′-trimethylstilbene glycidyl etherified product is particularly preferred. As the stilbene type epoxy resin of the general formula (4), 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylstilbene, 4,4′-dihydroxy-3 is used from the viewpoint of performance and raw material price. Particularly preferred are glycidyl etherified products of 3,3′-ditertiarybutyl-6,6′-dimethylstilbene and 4,4′-dihydroxy-3,3′-ditertiarybutyl-5,5′-dimethylstilbene.
[0013]
The phenol resin used in the present invention refers to monomers, oligomers, and polymers in general having two or more phenolic hydroxyl groups in one molecule. Examples thereof include phenol novolac resins, cresol novolac resins, paraxylylene-modified phenol resins, paraxylylene / metaxylylene-modified phenol resins, terpene-modified phenol resins, dicyclopentadiene-modified phenol resins, and the like. These may be used alone or in combination. These phenol resins can be used without limitation in terms of molecular weight, softening point, hydroxyl equivalent, and the like.
The equivalent ratio of epoxy groups of all epoxy resins used in the present invention to phenolic hydroxyl groups of all phenol resins is preferably 0.5 to 2, particularly preferably 0.7 to 1.5. If it is out of the range of 0.5 to 2, curability, moisture resistance and the like are lowered, which is not preferable.
[0014]
The curing accelerator used in the present invention is a conjugate base of tetra-substituted phosphonium and a compound having two or more phenolic hydroxyl groups in one molecule (hereinafter, in the present invention, it has two or more phenolic hydroxyl groups in one molecule). The conjugate base of the compound is called an anion). The conductivity of the extraction water of the compound having two or more phenolic hydroxyl groups in one molecule to be used needs to be 1000 μS / cm or less.
In the method for measuring the conductivity of the extracted water in the present invention, 1 g of a compound having two or more phenolic hydroxyl groups in one molecule is mixed with 50 g of pure water (the conductivity of pure water to be used is 5 μS / cm or less). After processing in a pressure cooker container at 125 ° C. for 20 hours, the content of the pressure cooker container is taken out and centrifuged, and the electric conductivity of the aqueous layer is measured by a conductivity meter (ES- manufactured by Horiba, Ltd.). 14 type) and measured at room temperature.
That is, the curing accelerator of the present invention comprises a salt of a tetra-substituted phosphonium and a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule having an extraction water conductivity of 1000 μS / cm or less. It is.
[0015]
Examples of such salts include tetraphenylphosphonium resorcin salt, tetraphenylphosphonium bisphenol A salt, tetraphenylphosphonium bisphenol F salt, tetraphenylphosphonium bisphenol S salt, tetraphenylphosphonium biphenol salt, tetraphenylphosphonium dihydroxynaphthalene salt, tetra Phenylphosphonium phenol novolak resin salt, tetraphenylphosphonium aralkyl-modified phenol resin salt, tetrabutylphosphonium bisphenol A salt, tetrabutylphosphonium bisphenol F salt, tetrabutylphosphonium bisphenol S salt, tetrabutylphosphonium biphenol salt, tetrabutylphosphonium dihydroxynaphthalene salt, Tetrabutylphosphonium pheno Lunovolak resin salt, tetrabutylphosphonium aralkyl-modified phenol resin salt, triphenylethylphosphonium bisphenol A salt, tolylmethylphosphonium bisphenol F salt, trianisylethylphosphonium biphenol salt, triphenylbutylphosphonium dihydroxynaphthalene salt, triphenylethylphosphonium phenol novolak Examples thereof include resin salts and triphenylbutylphosphonium aralkyl-modified phenol resin salts.
[0016]
In the component (C), excellent moisture resistance reliability is obtained when the conductivity of the extraction water of a compound having two or more phenolic hydroxyl groups in one molecule which is a conjugate acid of an anion is 1000 μS / cm or less. Is a prerequisite for. This is because, in the pressure cooker bias test (PCBT), it is considered that the electrophoretic phenomenon caused by ionic impurities occurs around the element to which the voltage is applied. This is because it is considered that there is a correlation between the rate and the moisture resistance reliability. In addition, when the compound having a phenolic hydroxyl group has less than 2 phenolic hydroxyl groups in one molecule, the corresponding conjugate base has low reactivity, so that it is not incorporated into the crosslinked structure upon curing and released. Conjugated bases may affect moisture resistance reliability and curability. On the other hand, the substituent of the phosphorus atom on the cation side preferably has water repellency, and particularly preferably a phenyl group.
From the above, the tetrasubstituted phosphonium of component (C) is tetraphenylphosphonium, and the conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule is resorcin, bisphenol A, bisphenol F, bisphenol S, Most preferred is one selected from the group consisting of a conjugate base of biphenol, dihydroxynaphthalene, phenol novolac resin, aralkyl-modified phenol resin.
Moreover, in the range which does not impair the characteristic of these hardening accelerators, it uses together with other hardening accelerators, such as a triphenylphosphine, 1, 8- diazabicyclo (5,4,0) undecene-7, 2-methylimidazole. There is no problem.
[0017]
There is no restriction | limiting in particular about the kind of inorganic filler used for this invention, What is generally used for the sealing material can be used. Examples thereof include fused crushed silica powder, fused spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, alumina, titanium white, aluminum hydroxide, talc, clay, and glass fiber, with fused spherical silica powder being particularly preferred. The shape is preferably infinitely spherical, and the amount of filling can be increased by mixing particles having different particle sizes.
As a compounding quantity of this inorganic filler, 200-2400 weight part is preferable per 100 weight part of total amounts of all the epoxy resins and all the phenol resins. If the amount is less than 200 parts by weight, the reinforcing effect of the inorganic filler may not be sufficiently exhibited. If the amount exceeds 2400 parts by weight, the fluidity of the resin composition may be reduced, and there is a risk of poor filling during molding. Absent. In particular, if the blending amount of the inorganic filler is 250 to 1400 parts by weight per 100 parts by weight of the total amount of all epoxy resins and all phenolic resins, the moisture absorption rate of the cured product of the resin composition becomes low, and solder cracks are generated. Further, since the viscosity of the resin composition at the time of melting is lowered, there is no possibility of causing gold wire deformation inside the semiconductor device, which is more preferable. Moreover, it is preferable that the inorganic filler is sufficiently mixed in advance.
[0018]
The resin composition of the present invention includes components (A) to (D), a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a colorant such as carbon black, a brominated epoxy resin, if necessary. Various additives such as flame retardants such as antimony oxide and phosphorus compounds, low stress components such as silicone oil and silicone rubber, mold release agents such as natural wax, synthetic wax, higher fatty acids and their metal salts or paraffin, and antioxidants Can be blended.
The resin composition of the present invention is obtained by mixing the components (A) to (D) and other additives at room temperature using a mixer, kneading with a kneader such as a roll or an extruder, pulverizing after cooling. It is done.
In order to seal an electronic component such as a semiconductor and manufacture a semiconductor device using the resin composition of the present invention, it may be cured by a molding method such as a transfer mold, a compression mold, or an injection mold.
[0019]
【Example】
Examples are described below, but the present invention is not limited to these examples. The blending ratio is parts by weight.
First, the structure of the compounds 1-6 which are the hardening accelerators used by the Example and the comparative example is collectively shown below.
In Table 1, the names of the conjugate acids corresponding to the conjugate bases of the compounds having a phenolic hydroxyl group of compounds 1 to 6 and 1 g of each conjugate acid are mixed with 50 g of pure water, and the mixture is 125 ° C., 20 ° C. in a pressure cooker vessel. The conductivity of the extracted water obtained by the time treatment is shown together.
[0020]
Compound 1
[Chemical 9]

[0021]
Compound 2
Embedded image

[0022]
Compound 3
Embedded image

[0023]
Compound 4
Embedded image

[0024]
Compound 5
Embedded image

[0025]
Compound 6
Embedded image

[0026]
[Table 1]

[0027]
Example 1
Resin based on biphenyl type epoxy resin of formula (5) (epoxy equivalent 185, melting point 105 ° C.) 51 parts by weight

49 parts by weight of phenolic resin of formula (6) (softening point 73 ° C.)
Embedded image

Compound 1 3.8 parts by weight fused spherical silica (average particle size 15 μm) 500 parts by weight carbon black 2 parts by weight brominated bisphenol A type epoxy resin 2 parts by weight carnauba wax 2 parts by weight were mixed and 95 The mixture was kneaded at 8 ° C. for 8 minutes, cooled and pulverized to obtain a resin composition. The obtained resin composition was evaluated by the following methods. The results are shown in Table 2.
[0029]
Evaluation Method Spiral Flow: Using a mold for spiral flow measurement according to EMMI-I-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. Spiral flow is a fluidity parameter, and a larger value means better fluidity. The unit is cm.
Shore D hardness: Molded at a mold temperature of 175 ° C., an injection pressure of 70 kg / cm ² , and a curing time of 2 minutes, and the value of Shore D hardness measured 10 seconds after mold opening is defined as curability. Shore D hardness is an index of curability, and the larger the value, the better the curability.
Resistance to solder cracking: Mold temperature of 175 ° C., injection pressure of 70 kg / cm ² , curing time of 2 minutes, 8 pieces of 80 pQFP (thickness 2.0 mm) were molded, and treated at 85 ° C. and relative humidity of 85% for 168 hours. Then, it processed by IR reflow of 240 degreeC for 10 second, and observed the number of package cracks visually. When there are n cracked packages, n / 8 is displayed.
Storage at 30 ° C .: After storing at 30 ° C. for 6 months, the spiral flow was measured and expressed as a percentage of the spiral flow immediately after preparation. Units%.
Moisture resistance reliability: After molding 16 pDIP at a mold temperature of 175 ° C., a pressure of 70 kg / cm ² and a curing time of 2 minutes, post-curing was performed at 175 ° C. for 8 hours. After applying a voltage of 20 V in water vapor at 125 ° C. and 100% relative humidity, the disconnection failure was examined. The time until a defect appears in 8 or more of the 15 packages was defined as a defect time. The unit is time. The measurement time was 500 hours at the longest, and when the number of defective packages was less than 8 at that time, the defective time was indicated as 500 hours or more. The longer the defect time, the better the moisture resistance reliability.
[0030]
Examples 2-8, Comparative Examples 1-3
According to the formulations in Tables 2 and 3, resin compositions were obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.
The crystalline epoxy resin A used in Example 2 is a resin 60 mainly composed of 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethylstilbene. A mixture of 40% by weight of a resin based on 4,4′-bis (2,3-epoxypropoxy) -5-tertiarybutyl-2,3 ′, 5′-trimethylstilbene (epoxy) Equivalent 209, melting point 120 ° C.).
The ortho-cresol novolak type epoxy resin used in Example 3 has an epoxy equivalent of 200 and a softening point of 65 ° C.
The phenol novolac resin used in Example 3 has a hydroxyl group equivalent of 104 and a softening point of 105 ° C.
In Comparative Example 1, when the compound 6 having a conductivity of the corresponding conjugate acid extracted water exceeding 1000 μS / cm was used as the curing accelerator, the moisture resistance reliability was lowered.
In Comparative Example 2, when triphenylphosphine was used as the curing accelerator, although the failure time in the moisture resistance reliability was good, the storage stability was lowered.
In Comparative Example 3, when Compound 1 was used as the curing accelerator and 180 parts by weight of fused spherical silica as the inorganic filler was used, the amount of the inorganic filler was small and the solder crack resistance was lowered.
[Table 2]

[0031]
[Table 3]

[0032]
【The invention's effect】
The epoxy resin composition of the present invention is extremely excellent in room temperature storage characteristics and moldability for semiconductor encapsulation, and a semiconductor device using the epoxy resin composition is excellent in moisture resistance reliability and useful as a device for insertion mounting and surface mounting. .

Claims (7)

(A) epoxy resin, (B) phenol resin, (C) a salt of tetra-substituted phosphonium as a curing accelerator and a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule, and in one molecule Extracted water obtained by mixing 1 g of a compound having two or more phenolic hydroxyl groups with 50 g of pure water (conductivity of pure water used is 5 μS / cm or less) and treating in a pressure cooker vessel at 125 ° C. for 20 hours. those conductivity of at most 1000 .mu.s / cm, and (D) an inorganic filler as essential components, the equivalent ratio of the phenolic hydroxyl groups of the epoxy group and total phenolic resin of the total epoxy resin is 0.5 to 2, Epoxy for semiconductor encapsulation, wherein the blending amount of the inorganic filler (D) is 200 to 2400 parts by weight per 100 parts by weight of the total amount of all epoxy resins and all phenol resins Shi resin composition. A conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule is composed of a conjugate base of resorcin, bisphenol A, bisphenol F, bisphenol S, biphenol, dihydroxynaphthalene, phenol novolac resin, aralkyl-modified phenol resin. The epoxy resin composition for semiconductor encapsulation according to claim 1, which is one or more selected. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the tetra-substituted phosphonium is tetraphenylphosphonium. The epoxy resin composition for semiconductor encapsulation according to claim 1, 2 or 3, wherein the epoxy resin is a crystalline epoxy resin having a melting point of 50 to 150 ° C. The epoxy resin composition for semiconductor encapsulation according to claim 4, wherein the crystalline epoxy resin having a melting point of 50 to 150 ° C. is at least one selected from the general formula (1) and the general formula (2).

(In the formula, R ¹ is a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, or a group or atom selected from halogens, which may be the same or different from each other. Good.)

(In the formula, R ² is a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, or a group or atom selected from halogens, which may be the same or different from each other. Good.) 5. The semiconductor encapsulation according to claim 4, wherein the crystalline epoxy resin having a melting point of 50 to 150 ° C. is a mixture of a stilbene type epoxy resin represented by the general formula (3) and a stilbene type epoxy resin represented by the general formula (4). use epoxy resin composition.

(In the formula, R ^{3 to} R ¹⁰ each independently represents a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon The two aryl groups bonded to the double bond are different from each other.)

(Wherein R ^{11 to} R ¹⁴ each independently represents a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon The two aryl groups bonded to the double bond are the same as each other.) A semiconductor device sealed with the epoxy resin composition for semiconductor sealing according to claim 1, 2, 3, 4, 5 or 6.