JPH0521133B2

JPH0521133B2 -

Info

Publication number: JPH0521133B2
Application number: JP60020103A
Authority: JP
Inventors: Keiichiro Ishii; Kenichi Suzuki
Original assignee: Sumitomo Bakelite Co Ltd
Current assignee: Sumitomo Bakelite Co Ltd
Priority date: 1985-02-06
Filing date: 1985-02-06
Publication date: 1993-03-23
Also published as: JPS61181820A

Description

【発明の詳細な説明】〔産業上の利用分野〕本発明は、ガラス転移温度を下げずに耐熱衝撃
性を付与した半導体封止用熱硬化性樹脂組成物に
関するものである。〔従来技術〕半導体製品の技術革新は目覚ましく高密度化と
ともに素子サイズの大型化、パツケージの小形、
薄形化、更に実装の合理化により封止用樹脂に対
する要求は一段と厳しいものになつてきている。
従来一般にノボラツク型エポキシ樹脂、ノボラツ
ク硬化剤の配合物が多く用いられているが成形品
を半田浸漬処理するとその急激な熱衝撃によつて
樹脂またはチツプのクラツク、リードフレームま
たはチツプとの界面剥離などの欠陥を生じて耐湿
性、信頼性の大巾な低下をひき起こしている。一方、通常の２官能性エポキシ樹脂、例えば油
化シエルエポキシ社製のエピコート828と２官能
性イソシアネート化合物、例えば４，4′−ジフエ
ニルメタンジイソシアネートとを反応させてイソ
シアネート変性エポキシ樹脂を得ることは特開昭
50−48100号公報、特開昭55−160021号公報など
により公知であるが塩素含有率が比較的多いため
この分野に適用しても耐湿性、信頼性が悪くて使
えない。また、これらの公知の製造方法を、塩素含有率
の少ない２官能性エポキシ樹脂に適用しても適度
な融点と溶融粘度を有する保存性の良い固形の変
性エポキシ樹脂を得ることは困難であつた。〔発明の目的〕本発明は、従来のエポキシ樹脂封止における半
田浸漬処理による耐湿性、信頼性の大巾な低下を
克服せんとして研究した結果、塩素含有率の少な
いイソシアヌレートおよびオキサゾリドン環を含
有する変性エポキシ樹脂を用いることにより半導
体封止装置の耐熱衝撃性が改善されるとの知見を
得、更にこの知見を基に種々研究を進めて本発明
を完成するに至つたものである。その目的とするところは、ガラス転移温度を下
げずに耐熱衝撃性を付与した塩素含有率の少ない
半導体封止用熱硬化性樹脂組成物を提供するにあ
る。〔発明の構成〕本発明は、(a)塩素含有率1000ppm以下の２官能
性エポキシ化合物と２官能性イソシアネート化合
物とを反応触媒の存在下、反応させて得られる融
点が50〜100℃の変性エポキシ樹脂、(b)ノボラツ
ク型フエノール樹脂、および(c)硬化促進剤を含む
ことを特徴とする熱硬化性樹脂組成物である。本発明において用いられる２官能性エポキシ化
合物は、塩素含有率1000ppm以下の１分子中に２
個のエポキシ基を有するビスフエノールＡあるい
はビスフエノールＦ型のもので好ましくはエポキ
シ当量が500以下のものがよい。塩素含有率は、多いと耐湿性、信頼性が悪化す
る。２官能性エポキシの樹脂骨格は、経済性、作
業性および反応性などからビスフエノールＡある
いはビスフエノールＦ型のものがバランスがとれ
ていてよい。エポキシ当量は、大き過ぎると得ら
れる変性樹脂の融点、溶融粘度が高くなり、作業
性が非常に悪くなる。２官能性イソシアネート化合物は、通常の芳香
族ジイソシアネート、例えばフエニレンジイソシ
アネート、トリレンジイソシアネート、キシリレ
ン−ジイソシアネート、ジフエニルメタンジイソ
シアネート、ジフエニルエーテルジイソシアネー
ト、またはこれらの混合物である。好ましくは塩
素含有率100ppm以下のものがよい。２官能性イソシアネート化合物は、分割して添
加するとよい。最初は２官能性エポキシ化合物
100部に対して４〜10部を反応させ、後からその
総量が15〜30部になるように逐次添加するとよ
い。塩素含有率の少ない２官能性エポキシ化合物と
２官能性イソシアネート化合物との反応は、塩素
含有率の比較的多い通常の２官能性エポキシ樹脂
の場合と異なり、これらの２官能性イソシアネー
ト化合物を最初に全量添加するか、または一様の
速さで逐次添加するとオキサゾリドン環の生成が
極度に減少する。得られる変性樹脂はイソシアヌ
レート環は生成しているが、イソシアネート基が
多量に残存する保存性の悪い粘稠な樹脂状物か、
またはゲル化物で適度な融点を有する保存性の良
い変性樹脂は得られない。その作用機構は、まだ
定かでないが不純物として存在する少量の塩素が
オキサゾリドン環の生成に大きく関与している。
２官能性イソシアネート化合物は、少な過ぎると
得られる変性樹脂の融点が低く、常温では粘稠な
樹脂状物となり、作業性が悪く、また硬化物のガ
ラス転移温度が低下し、耐熱性、耐湿性、信頼性
もよくなり、多過ぎると融点および溶融粘度が高
くなつて作業が困難になり、反応中ゲル化し易く
なる。反応触媒は、通常の３級アミン、イミダゾール
類、ホスフイン類などが使用できる。特に１，８
−ジアザ−ビシクロ〔５，40〕−ウンデセン−７
−（以下DBUという）またはそのフエノールある
いはフエノール系化合物塩が有効である。反応触
媒量は、２官能性エポキシ化合物100部に対し
0.005〜0.08部が適当で多過ぎるとゲル化し易く、
少な過ぎると反応が非常に遅く、またオキサゾリ
ドン環の生成が減少して適度な融点の保存性の良
い変性樹脂が得られない。反応温度は140〜180℃の範囲がよい。低過ぎる
とオキサゾリドン環の生成が減し、適度な融点の
保存性のよいものが得られず、高過ぎるとゲル化
し易く、反応のコントロールが難しくなる。変性エポキシ樹脂の融点は50〜100℃がよい。
この範囲をはずれると作業性、成形性が悪化し十
分な特性が得られない。ノボラツク型フエノール樹脂は、通常エポキシ
樹脂硬化剤として用いられるものでよい。その使
用量は変性エポキシ樹脂のエポキシ当量によつて
決められる。硬化促進剤としては、３級アミン、イミダゾー
ル類、ホスフイン類などが使用できる。特に、
１，８−ジアザ−ビシクロ〔５，40〕−ウンデセ
ン−７（DBU）または、そのフエノールあるいは
フエノール系化合物塩が有効である。硬化促進剤
量は(a)＋(b)100部に対して0.1〜2.0部がよい。少な過ぎると硬化性が悪く十分な性能が得られ
ない。多過ぎるとロール混練時フローの詰りが速
くなつて配合物の均一な混合が困難になる。本発明の組成物は、更に必要に応じてノボラツ
ク型エポキシ樹脂、充てん剤、表面処理剤、離型
剤、着色剤などを配合し、混合または混練して成
形材料となる。〔発明の効果〕本発明方法に従うと塩素含有率の少ない２官能
性エポキシ樹脂でもイソシアネート基が消失して
オキサゾリドン環およびイソシアヌレート環を形
成し適度な融点および溶融粘度の変性エポキシ樹
脂が得られる。これにイボラツク型フエノール樹
脂、硬化促進剤などを配合して半導体封止用に用
いるとガラス転移温度を下げずに半田処理の熱衝
撃に耐える耐湿性の良い成形品が得られるので、
工業的な半導体封止用熱硬化性樹脂組成物として
好適である。〔実施例〕実施例１〜３塩素含有率500ppmのビスフエノールＡ型エポ
キシ樹脂（エポキシ当量：（175）100部と、２，
４−トリレンジイソシアネート７部に、
DBU0.01部を加え、150℃で攪拌しながら60分反
応させ、これに２，４−トリレンジイソシアネー
ト15部を60分かけて滴下し、更に60分反応させ
た。得られた変性エポキシ樹脂は、赤外スペクトル
で2260cm^-1のイソシアネート基の吸収が消失し、
1750cm^-1オキサゾリドン環のＣ＝０と、1710cm^-1
のイソシアヌレート環のＣ＝０の吸収がほぼ同程
度認められ910cm^-1のエポキシ基の吸収も残存し
ていた。融点68℃。エポキシ当量：300。この変性エポキシ樹脂に、オルソクレゾールノ
ボラツク型エポキシ樹脂（EOCN−102：日本化
薬社製）、ノボラツク型フエノール樹脂（PR−
51470：住友デユレズ社製）、硬化促進剤、シリカ
粉末、エポキシシラン、離型剤を配合し、ロール
混練して成形材料を得トランスフアー成形により
成形した。その特性は第１表に示した。比較例１実施例１の２，４−トリレンジイソシアネート
を分割せずに全量22部を最初に添加し、150℃で
攪拌しながら180分反応させた。得られた樹脂は
赤外スペクトルで2260cm^-1のイソシアネート基の
吸収が残存し、1710cm^-1のオキサゾリドン環のＣ
＝０の吸収は殆んど認められなかつた。室温では
粘稠な樹脂状物であつた。比較例２実施例１の２，４−トリレンジイソシアネート
の全量を60分かけて逐次添加し、更に120分反応
させた。得られた樹脂は赤外スペクトルで、2260
cm^-1のイソシアネート基の吸収が残存し、1710cm
^-1のイソシアヌレート環のＣ＝０は生成している
が、1750cm^-1のオキサゾリドン環のＣ＝０の吸収
は極くわずかであつた。室温では粘稠な樹脂状物
であつた。比較例３実施例１の変性エポキシ樹脂をオルソクレゾー
ルノボラツク型エポキシ樹脂に置き換えて成形材
料を得、成形しその特性を第１表に示す。実施例４〜５塩素含有率450ppmのビスフエノールＦ型エポ
キシ樹脂（エポキシ当量：165）100部と、４，
4′−ジフエニルメタンジイソシアネート８部に、
２−エチル−４−メチルイミダゾール0.03部を加
え170℃で攪拌しながら45分反応させ、これに２，
４−トリレンジイソシアネート12部を45分かけて
滴下し、更に60分反応させた。得れた変性樹脂はイソシアネート基の残存しな
い、オキサゾリドン環のＣ＝０とイソシアヌレー
ト環のＣ＝０の赤外スペクトルがほぼ同程度のエ
ポキシ樹脂であつた。融点70℃。エポキシ当量
320。これを実施例１と同様に配合して材料化し、成
形した。その特性は第１表に示した。実施例１〜５のガラス転移温度は、ノボラツク
型エポキシ樹脂の比較例３とほぼ同じである。比較例３は半田浸漬処理による吸湿速度の増加
が大きいのに対し、実施例１〜５は小さい。熱時
の曲げ弾性率も比較例３に比べ小さくなつていて
本発明の熱硬化性樹脂組成物はガラス転移温度を
下げずに耐熱衝撃性が付与されている。【表】DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a thermosetting resin composition for semiconductor encapsulation that provides thermal shock resistance without lowering the glass transition temperature. [Conventional technology] Technological innovations in semiconductor products have been remarkable, resulting in higher density, larger element sizes, smaller packages,
Due to thinning and rationalization of packaging, the requirements for sealing resins are becoming even more stringent.
Conventionally, compounds of novolac type epoxy resin and novolac curing agent are often used, but when molded products are subjected to solder immersion treatment, the rapid thermal shock causes cracks in the resin or chip, and interface peeling with the lead frame or chip. This causes defects in moisture resistance and reliability. On the other hand, it is not possible to obtain an isocyanate-modified epoxy resin by reacting a normal bifunctional epoxy resin, such as Epicote 828 manufactured by Yuka Ciel Epoxy Co., with a bifunctional isocyanate compound, such as 4,4'-diphenylmethane diisocyanate. Tokukai Akira
Although it is known from Japanese Patent Application Laid-open No. 50-48100 and Japanese Patent Application Laid-open No. 55-160021, it cannot be used in this field because of its relatively high chlorine content and poor moisture resistance and reliability. Furthermore, even if these known production methods were applied to bifunctional epoxy resins with a low chlorine content, it was difficult to obtain a solid modified epoxy resin with a suitable melting point and melt viscosity and good shelf life. . [Object of the Invention] The present invention was developed as a result of research aimed at overcoming the drastic deterioration in moisture resistance and reliability due to solder immersion treatment in conventional epoxy resin sealing. The inventors have found that the thermal shock resistance of semiconductor encapsulation devices can be improved by using a modified epoxy resin, and based on this knowledge, they have carried out various studies and have completed the present invention. The objective is to provide a thermosetting resin composition for semiconductor encapsulation that has a low chlorine content and that imparts thermal shock resistance without lowering the glass transition temperature. [Structure of the Invention] The present invention provides (a) a modified compound having a melting point of 50 to 100°C obtained by reacting a bifunctional epoxy compound with a chlorine content of 1000 ppm or less and a bifunctional isocyanate compound in the presence of a reaction catalyst; This is a thermosetting resin composition characterized by containing an epoxy resin, (b) a novolak type phenolic resin, and (c) a curing accelerator. The bifunctional epoxy compound used in the present invention has a chlorine content of 1000 ppm or less and has 2
A bisphenol A or bisphenol F type having an epoxy group of 50 to 500 epoxy equivalents is preferred. If the chlorine content is too high, moisture resistance and reliability will deteriorate. The resin skeleton of the bifunctional epoxy may be of the bisphenol A or bisphenol F type in view of economy, workability, reactivity, and the like. If the epoxy equivalent is too large, the melting point and melt viscosity of the resulting modified resin will increase, resulting in very poor workability. The difunctional isocyanate compounds are customary aromatic diisocyanates, such as phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, or mixtures thereof. Preferably, the chlorine content is 100 ppm or less. The bifunctional isocyanate compound is preferably added in portions. Initially a difunctional epoxy compound
It is preferable to react 4 to 10 parts per 100 parts, and then add sequentially so that the total amount becomes 15 to 30 parts. The reaction between a bifunctional epoxy compound with a low chlorine content and a bifunctional isocyanate compound is different from the case of a normal bifunctional epoxy resin with a relatively high chlorine content. Adding the entire amount or adding sequentially at a uniform rate will greatly reduce the formation of oxazolidone rings. Although the obtained modified resin has isocyanurate rings formed, it is a viscous resin-like material with poor storage stability and a large amount of isocyanate groups remaining.
Alternatively, a modified resin with a suitable melting point and good storage stability cannot be obtained from a gelled product. The mechanism of action is not yet clear, but a small amount of chlorine present as an impurity is largely involved in the formation of oxazolidone rings.
If the amount of bifunctional isocyanate compound is too small, the melting point of the resulting modified resin will be low, and it will become a viscous resin-like material at room temperature, resulting in poor workability, and the glass transition temperature of the cured product will decrease, resulting in poor heat resistance and moisture resistance. If the amount is too high, the melting point and melt viscosity will become high, making the work difficult and causing gelation during the reaction. As the reaction catalyst, common tertiary amines, imidazoles, phosphines, etc. can be used. Especially 1,8
-Diaza-bicyclo[5,40]-Undecene-7
- (hereinafter referred to as DBU) or its phenol or phenolic compound salts are effective. The amount of reaction catalyst is per 100 parts of difunctional epoxy compound.
A suitable amount is 0.005 to 0.08 parts; too much will cause gelation.
If the amount is too small, the reaction will be very slow and the formation of oxazolidone rings will be reduced, making it impossible to obtain a modified resin with a suitable melting point and good storage stability. The reaction temperature is preferably in the range of 140 to 180°C. If it is too low, the formation of oxazolidone rings will be reduced, making it impossible to obtain a product with an appropriate melting point and good shelf life; if it is too high, it will tend to gel, making it difficult to control the reaction. The melting point of the modified epoxy resin is preferably 50 to 100°C.
If it is outside this range, workability and moldability will deteriorate and sufficient properties will not be obtained. The novolak type phenolic resin may be one commonly used as an epoxy resin curing agent. The amount used is determined by the epoxy equivalent of the modified epoxy resin. As the curing accelerator, tertiary amines, imidazoles, phosphines, etc. can be used. especially,
1,8-diaza-bicyclo[5,40]-undecene-7 (DBU) or its phenol or phenolic compound salts are effective. The amount of curing accelerator is preferably 0.1 to 2.0 parts per 100 parts of (a)+(b). If it is too small, curing properties will be poor and sufficient performance will not be obtained. If the amount is too large, the flow will become clogged quickly during roll kneading, making it difficult to mix the compound uniformly. The composition of the present invention is further blended with a novolak type epoxy resin, a filler, a surface treatment agent, a mold release agent, a coloring agent, etc. as required, and is mixed or kneaded to become a molding material. [Effects of the Invention] According to the method of the present invention, even in a bifunctional epoxy resin with a low chlorine content, isocyanate groups disappear to form oxazolidone rings and isocyanurate rings, and a modified epoxy resin with an appropriate melting point and melt viscosity can be obtained. If this is mixed with Ivorak-type phenolic resin, curing accelerator, etc. and used for semiconductor encapsulation, a molded product with good moisture resistance that can withstand the thermal shock of soldering without lowering the glass transition temperature can be obtained.
It is suitable as a thermosetting resin composition for industrial semiconductor encapsulation. [Example] Examples 1 to 3 Bisphenol A type epoxy resin with a chlorine content of 500 ppm (epoxy equivalent: (175) 100 parts, 2,
7 parts of 4-tolylene diisocyanate,
0.01 part of DBU was added and reacted for 60 minutes with stirring at 150°C. 15 parts of 2,4-tolylene diisocyanate was added dropwise over 60 minutes and reacted for an additional 60 minutes. In the obtained modified epoxy resin, the isocyanate group absorption at 2260 cm ^-1 disappears in the infrared spectrum,
1750cm ^-1 C=0 of oxazolidone ring and 1710cm ^-1
Almost the same degree of absorption at C=0 of the isocyanurate ring was observed, and the absorption at 910 cm ^-1 of the epoxy group also remained. Melting point 68℃. Epoxy equivalent weight: 300. To this modified epoxy resin, orthocresol novolac type epoxy resin (EOCN-102: manufactured by Nippon Kayaku Co., Ltd.), novolac type phenolic resin (PR-
51470 (manufactured by Sumitomo Durez), a curing accelerator, silica powder, epoxy silane, and a mold release agent were blended and kneaded with rolls to obtain a molding material, which was molded by transfer molding. Its properties are shown in Table 1. Comparative Example 1 A total of 22 parts of the 2,4-tolylene diisocyanate of Example 1 was first added without dividing it, and the mixture was reacted at 150° C. for 180 minutes with stirring. In the infrared spectrum of the obtained resin, absorption of the isocyanate group at 2260 cm ^-1 remains, and absorption of C of the oxazolidone ring at 1710 cm ^-1 remains.
Absorption of =0 was hardly observed. At room temperature, it was a viscous resin-like substance. Comparative Example 2 The entire amount of 2,4-tolylene diisocyanate in Example 1 was added sequentially over 60 minutes, and the reaction was further continued for 120 minutes. The resulting resin has an infrared spectrum of 2260
cm ^-1 absorption of isocyanate group remains, 1710 cm
Although C=0 of the isocyanurate ring at ^-1 was formed, the absorption of C=0 of the oxazolidone ring at 1750 cm ^-1 was extremely small. At room temperature, it was a viscous resin-like substance. Comparative Example 3 A molding material was obtained by replacing the modified epoxy resin of Example 1 with an orthocresol novolak type epoxy resin, and the properties of the molded material are shown in Table 1. Examples 4 to 5 100 parts of bisphenol F type epoxy resin (epoxy equivalent: 165) with a chlorine content of 450 ppm, and 4,
8 parts of 4'-diphenylmethane diisocyanate,
Add 0.03 part of 2-ethyl-4-methylimidazole and react for 45 minutes with stirring at 170°C.
12 parts of 4-tolylene diisocyanate was added dropwise over 45 minutes, and the reaction was continued for an additional 60 minutes. The obtained modified resin was an epoxy resin in which no isocyanate group remained and the infrared spectra of C=0 in the oxazolidone ring and C=0 in the isocyanurate ring were almost the same. Melting point 70℃. Epoxy equivalent
320. This was mixed and made into a material in the same manner as in Example 1, and molded. Its properties are shown in Table 1. The glass transition temperatures of Examples 1 to 5 are approximately the same as Comparative Example 3, which is a novolak type epoxy resin. In Comparative Example 3, the increase in moisture absorption rate due to the solder immersion treatment is large, whereas in Examples 1 to 5, it is small. The flexural modulus under heat is also smaller than that of Comparative Example 3, and the thermosetting resin composition of the present invention is provided with thermal shock resistance without lowering the glass transition temperature. 【table】

Claims

[Claims] 1(a) 100 parts of a bifunctional epoxy compound with a chlorine content of 1000 ppm or less and 4 to 10 parts of a bifunctional isocyanate compound are reacted in the presence of 0.005 to 0.08 parts of a reaction catalyst, and then A modified epoxy resin with a melting point of 50 to 100°C obtained by sequentially adding and reacting bifunctional isocyanurate compounds such that the total amount of the bifunctional isocyanurate compounds is 15 to 30 parts, (b) a novolac type phenolic resin, and (c) A thermosetting resin composition characterized by containing a curing accelerator.