JP2004285316A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition having a high adhesion strength to a non-copper frame and excellent in solder resistance, and a semiconductor device. <P>SOLUTION: This epoxy resin composition for sealing the semiconductor is characterized by containing (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler and (E) a disulfide-based compound without containing a heterocyclic ring, more preferably a compound expressed by general formula (1) (wherein, R1, R2 are each a 2-18C alkyl or aryl, and the R1, R2 may be the same or different). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

（式中、Ｒ１、Ｒ２は炭素数２〜１８のアルキル基又はアリール基。Ｒ１、Ｒ２は同じであっても異なっていてもよい。）
【０００９】
［３］ 前記の複素環を含まないジスルフィド系化合物が、樹脂組成物に対して０．０１〜２重量％の割合で含有される第［１］又は［２］項記載の半導体封止用エポキシ樹脂組成物、
［４］ 第［１］、［２］、又は［３］項のいずれかに記載のエポキシ樹脂組成物を用いて半導体素子を封止してなることを特徴とする半導体装置、
である。
【００１０】
【発明の実施の形態】
本発明に用いられるエポキシ樹脂は、１分子中に２個以上のエポキシ基を有するモノマー、オリゴマー、ポリマー全般であり、例えば、ハイドロキノン型エポキシ樹脂、ビスフェノールＡ型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂、ビフェニル型エポキシ樹脂、スチルベン型エポキシ樹脂、フェノールノボラック型エポキシ樹脂、クレゾールノボラック型エポキシ樹脂、ナフトールノボラック型エポキシ樹脂、トリフェノールメタン型エポキシ樹脂、アルキル変性トリフェノールメタン型エポキシ樹脂、ジシクロペンタジエン変性フェノール型エポキシ樹脂、フェノールアラルキル型エポキシ樹脂（フェニレン骨格、ビフェニレン骨格等を有する）、ナフトールアラルキル型エポキシ樹脂（フェニレン骨格、ビフェニレン骨格等を有する）、テルペン変性フェノール型エポキシ樹脂、トリアジン核含有エポキシ樹脂等が挙げられるが、これらに限定されるものではない。これらのエポキシ樹脂は単独でも併用してもよい。
半導体装置の耐半田性を向上させることを目的に、エポキシ樹脂組成物中の無機質充填材の配合量を増大させ、得られたエポキシ樹脂組成物の硬化物の低吸湿化、低熱膨張化、高強度化を達成させる場合には、常温で結晶性を示し融点を越えると極めて低粘度の液状となる結晶性エポキシ樹脂を全エポキシ樹脂中に３０重量％以上用いることが特に好ましい。
【００１１】
本発明に用いられるフェノール樹脂としては、１分子中に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、ポリマー全般であり、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、フェノールアラルキル樹脂（フェニレン骨格、ビフェニレン骨格等を有する）、ナフトールアラルキル樹脂（フェニレン骨格、ビフェニレン骨格等を有する）、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フェノール樹脂、ビスフェノール化合物等が挙げられるが、これらに限定されるものではない。これらのフェノール樹脂は単独でも２種類以上併用して用いてもよい。
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との当量比としては、好ましくは０．５〜２．０、特に好ましくは０．７〜１．５である。上記範囲を外れると、硬化性、耐湿信頼性等が低下する可能性がある。
【００１２】
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であり、例えばトリブチルアミン、１，８−ジアザビシクロ（５，４，０）ウンデセン−７等のアミン系化合物、トリフェニルホスフィン、テトラフェニルホスホニウム・テトラフェニルボレート塩等の有機リン系化合物、２−メチルイミダゾール等のイミダゾール化合物等が挙げられるが、これらに限定されるものではない。これらの硬化促進剤は単独でも併用してもよい。
【００１３】
本発明に用いられる無機質充填材としては、一般に半導体封止用エポキシ樹脂組成物に使用されているものを用いることができ、例えば、溶融シリカ、結晶シリカ、アルミナ、窒化珪素、窒化アルミ等が挙げられる。これらの無機質充填材は単独でも併用してもよい。
無機質充填材の配合量を多くする場合、溶融シリカを用いるのが一般的である。溶融シリカは、破砕状、球状のいずれでも使用可能であるが、溶融シリカの配合量を高め、かつエポキシ樹脂組成物の溶融粘度の上昇を抑えるためには、球状のものを主に用いる方が好ましい。更に溶融球状シリカの配合量を多くするためには、溶融球状シリカの粒度分布がより広くなるように調整することが望ましい。無機質充填材は、予めシランカップリング剤等で表面処理されているものを用いてもよい。
【００１４】
本発明で用いられる複素環を含まないジスルフィド系化合物は、ジスルフィド構造を有する化合物であり、樹脂組成物の硬化物とリードフレームとの密着性を向上させ、ひいては樹脂組成物の硬化物で半導体素子を封止してなる半導体装置の耐湿信頼性、耐リフロークラック性を改善させる役割を果たす。ジスルフィド構造を有する化合物は、特に樹脂組成物の硬化物と非銅リードフレーム（銀メッキリードフレーム、ニッケル／パラジウム合金に金メッキが施されたプレプリーティングフレーム）との密着性を向上させる効果が顕著であるため、上記リードフレームを用いた時に、半導体装置の信頼性が大幅に向上する。また、本発明で用いられる複素環を含まないジスルフィド系化合物は、複素環を含まないことが必須である。複素環は、Ｎ−Ｓ結合、Ｎ−Ｃ結合などの不安定な結合を多く含むため、加熱成形や半田処理工程の熱により分解してしまい、密着性に悪影響を与える可能性がある。従って、ジスルフィド構造の末端に複素環構造を持つ構造は熱安定性に問題がある。
本発明で用いられるジスルフィド系化合物としては、特に限定するものではないが一般式（１）で示される化合物であることが好ましい。ジスルフィドの両末端には、炭素数２〜１８のアルキル基又はアリール基が好ましい。化合物の分子量が大きいと、リードフレームとの密着性を向上させる効果が出難い可能性がある。また、加熱成形時の熱による揮発を防ぐため、ジスルフィド系化合物の沸点は１７５℃以上が好ましい。
【００１５】
【化３】

（式中、Ｒ１、Ｒ２は炭素数２〜１８のアルキル基又はアリール基。Ｒ１、Ｒ２は同じであっても異なっていてもよい。）
【００１６】
本発明で用いられる複素環を含まないジスルフィド系化合物の添加量は、特に限定するものではないが、樹脂組成物全体に対して０．０１〜２重量％の割合であることが好ましい。下限値を下回ると密着性向上の効果が薄れる可能性があり、上限値を超えると成形物の強度を低下させ、パッケージの信頼性を損なう恐れがある。
【００１７】
本発明のエポキシ樹脂組成物は、エポキシ樹脂、フェノール樹脂、無機充填材、硬化促進剤の他、必要に応じて、シランカップリング剤、チタネートカップリング剤、アルミニウムカップリング剤、アルミニウム／ジルコニウムカップリング剤等のカップリング剤、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、酸化ビスマス水和物等の無機イオン交換体、カーボンブラック、ベンガラ等の着色剤、シリコーンオイル、シリコーンゴム等の低応力化剤、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を適宜配合してもよい。
【００１８】
本発明のエポキシ樹脂組成物は、エポキシ樹脂、フェノール樹脂、無機充填材、硬化促進剤、及びその他の添加剤等をミキサーを用いて混合後、ロール、ニーダー、押出機等の混練機で加熱混練し、冷却後粉砕して得られる。
本発明のエポキシ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成形方法で硬化成形すればよい。
【００１９】
【実施例】
以下、本発明を実施例にて説明するが、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。
実施例１
【００２０】
式（２）で示されるエポキシ樹脂（軟化点５８℃、エポキシ当量２７２、以下エポキシ樹脂１とする） ８．２重量部
【化４】

【００２１】
式（３）で示されるフェノール樹脂（軟化点１０７℃、水酸基当量２００、以下フェノール樹脂１とする） ６．０重量部
【化５】

【００２２】
溶融球状シリカ（平均粒径２８μｍ） ８４．９重量部
１，８−ジアザビシクロ（５，４，０）ウンデセン−７（以下、ＤＢＵという） ０．２重量部
【００２３】
式（４）で示されるジ−ｔ−オクチルジスルフィド（東京化成、一級試薬）０．２重量部
【化６】

【００２４】
カルナバワックス ０．２重量部
カーボンブラック ０．３重量部
をミキサーを用いて混合した後、表面温度が９０℃と２５℃の２本ロールを用いて混練し、冷却後粉砕してエポキシ樹脂組成物を得た。得られたエポキシ樹脂組成物の特性を以下の方法で評価した。結果を表１に示す。
【００２５】
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６．９ＭＰａ、硬化時間１２０秒の条件で測定した。単位はｃｍ。
密着強度：トランスファー成形機を用いて、金型温度１７５℃、注入圧力９．８ＭＰａ、硬化時間１２０秒の条件で、リードフレーム上に２ｍｍ×２ｍｍ×２ｍｍの密着強度試験片を１水準当たり１０個成形した。リードフレームには銅フレームに銀メッキしたもの（フレーム１）とＮｉＰｄ合金フレームに金メッキしたもの（フレーム２）の２種類を用いた。その後、自動せん断強度測定装置（ＤＡＧＥ社製、ＰＣ２４００）を用いて、エポキシ樹脂組成物の硬化物とフレームとのせん断強度を測定した。１０個の試験片のせん断強度の平均値を表１に示す。単位はＮ／ｍｍ^２。
耐半田性：１７６ピンＬＱＦＰパッケージ（パッケージサイズは２４×２４ｍｍ、厚み２．０ｍｍ、シリコンチップのサイズは、８．０×８．０ｍｍ、リードフレームは１７６ｐｉｎプリプレーティングフレーム、ＮｉＰｄ合金にＡｕメッキ加工したもの。）を、金型温度１７５℃、注入圧力９．３ＭＰａ、硬化時間１２０秒の条件でトランスファー成形し、１７５℃で８時間の後硬化をした。得られたパッケージを８５℃、相対湿度６０％の環境下で１６８時間加湿処理した。その後このパッケージを２６０℃の半田槽に１０秒間浸漬した。半田処理を行ったパッケージを超音波探傷装置を用いて観察し、チップ（ＳｉＮコート品）とエポキシ樹脂組成物の硬化物との界面に剥離が発生した剥離発生率［（剥離発生パッケージ数）／（全パッケージ数）×１００］を％で表示した。
【００２６】
実施例２〜６、比較例１〜３
表１の配合に従い、実施例１と同様にしてエポキシ樹脂組成物を得、実施例１と同様にして評価した。これらの結果を表１に示す。用いたエポキシ樹脂およびフェノール樹脂の詳細は表２に示す。また、実施例１以外で用いたジスルフィド系化合物については下記に示す。
【００２７】
式（５）で示されるジ−ｔ−ドデシルジスルフィド（東京化成）
【化７】

【００２８】
式（６）で示されるジフェニルジスルフィド（東京化成）
【化８】

【００２９】
式（７）で示されるジベンジルジスルフィド（東京化成）
【化９】

【００３０】
式（８）で示されるジ−２−ベンゾチアゾリルジスルフィド（東京化成）
【化１０】

【００３１】
【表１】

【００３２】
【表２】

【００３３】
実施例１により、ジスルフィド系化合物を添加したエポキシ樹脂組成物は、リードフレームとの密着強度が高く、また、信頼性に優れているという結果が得られた。また、実施例２により樹脂の種類により差はあるがジスルフィド系化合物を添加することにより密着強度が大きくなっている。また、実施例３によりジスルフィド末端のアルキル鎖がある程度長くなっても効果が得られている。実施例４、５により、ジスルフィド両末端にベンゼン環を持つものも、アルキル鎖と同様な効果が得られることがわかった。実施例６はジスルフィド化合物を多量に添加したものであるが、流動性が低下しているものの密着強度、信頼性に優れた結果が得られている。比較例１，２はジスルフィド系化合物を添加しない系であるが、樹脂の種類に関わらず密着強度が低く、かつ、信頼性も低い結果が得られた。比較例３は、複素環を含むジスルフィド化合物である２−ベンゾチアゾリルジスルフィドを用いたものであるが、密着強度と信頼性が低下するという結果が得られた。
【００３４】
【発明の効果】
本発明のエポキシ樹脂組成物を用いて得られた半導体装置は、非銅リードフレームとの密着強度が強く、信頼性に優れている。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an epoxy resin composition for semiconductor encapsulation, and a semiconductor device using the same.
[0002]
[Prior art]
In recent years, in the market trend of miniaturization, weight reduction, and high functionality of electronic devices, as the integration of semiconductor elements is progressing year by year and the surface mounting of semiconductor devices is promoted, a new area mounting type semiconductor device is newly developed. Has been developed and has begun to shift from a semiconductor device having a conventional structure. In the area mounting type semiconductor device, a semiconductor element is mounted on one side of a flexible circuit board or the like, and only the semiconductor element mounting surface, that is, one side of the substrate is molded and sealed with an epoxy resin composition or the like. Further, on the surface opposite to the semiconductor element mounting surface of the substrate, solder balls are formed two-dimensionally in parallel and joined to the substrate on which the semiconductor device is mounted. Further, as a substrate on which a semiconductor element is mounted, a structure using a metal substrate such as a lead frame has been devised in addition to the organic substrate.
[0003]
When soldering these area-mounted semiconductor devices by means such as infrared reflow, vapor phase soldering, or solder immersion, the moisture present inside the semiconductor device due to the moisture absorption of the cured epoxy resin composition and the organic substrate is reduced. Cracks may occur in the semiconductor device due to the stress caused by rapid vaporization at high temperatures, and peeling may occur at the interface between the semiconductor element mounting surface of the substrate and the cured product of the epoxy resin composition. Along with high strength, low stress and low moisture absorption, high adhesion to the substrate is required.
[0004]
In order to improve reliability due to solder processing, increase the amount of inorganic filler in the epoxy resin composition to achieve low moisture absorption, high strength, low thermal expansion, and improve solder resistance A method of using a resin having a low melt viscosity to maintain a low viscosity and a high fluidity at the time of molding is becoming common.
On the other hand, the adhesiveness of the interface between the cured product of the epoxy resin composition and the base material such as a semiconductor element or a lead frame existing inside the semiconductor device has become very important in reliability after the soldering process. If the adhesive force at the interface is weak, peeling occurs at the interface with the substrate after the soldering, and further, cracks occur in the semiconductor device due to the peeling.
Conventionally, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ- (methacryloxypropyl) trimethoxysilane have been added to epoxy resin compositions for the purpose of improving solder resistance. However, in recent years, the demand for solder resistance, which has become increasingly severe, has been increasing, such as the rise in reflow temperature during mounting and the appearance of pre-plating frames made of Ni, Ni-Pd, Ni-Pd-Au, etc. in response to lead-free solder. Thus, these silane coupling agents alone cannot sufficiently cope.
As a countermeasure, a method of treating the surface of a lead frame with an alkoxysilane coupling agent (for example, see Patent Document 1), a resin composition containing a thiazole-based compound, a sulfenamide-based compound, and a thiuram-based compound, and a resin sealant are provided. 2. Description of the Related Art A fixed semiconductor device (for example, see Patent Documents 2 and 3) has been proposed. However, the former silane coupling agent has a disadvantage that the stability at the time of heat is poor and the effect of improving the adhesion in the soldering resistance treatment is reduced, and the latter compound has a large molecular weight and an unstable bond (nitrogen-sulfur). (Bonding), it has been pointed out that it may decompose in the sealing resin after molding.
[0005]
[Patent Document 1]
JP-A-6-350,000 (pages 2 to 5)
[Patent Document 2]
JP-A-62-209170 (pages 2 to 4)
[Patent Document 3]
JP-A-62-260344 (pages 2 to 4)
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide an epoxy resin composition excellent in reliability that does not cause peeling from a lead frame in a soldering process after absorbing moisture, and a semiconductor device.
[0007]
[Means for Solving the Problems]
The present invention
[1] A semiconductor encapsulation comprising (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) an inorganic filler, and (E) a disulfide compound containing no heterocycle. Epoxy resin composition for
[2] The epoxy resin composition for semiconductor encapsulation according to [1], wherein the disulfide compound not containing a heterocycle is a compound represented by the general formula (1):
[0008]
Embedded image

(In the formula, R1 and R2 are an alkyl group or an aryl group having 2 to 18 carbon atoms. R1 and R2 may be the same or different.)
[0009]
[3] The epoxy for semiconductor encapsulation according to [1] or [2], wherein the disulfide compound containing no heterocyclic ring is contained in a ratio of 0.01 to 2% by weight based on the resin composition. Resin composition,
[4] A semiconductor device obtained by sealing a semiconductor element using the epoxy resin composition according to any one of [1], [2], or [3].
It is.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The epoxy resin used in the present invention includes all monomers, oligomers and polymers having two or more epoxy groups in one molecule, such as hydroquinone type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl Epoxy resin, stilbene epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, naphthol novolak epoxy resin, triphenolmethane epoxy resin, alkyl-modified triphenolmethane epoxy resin, dicyclopentadiene-modified phenol epoxy resin Resin, phenol aralkyl type epoxy resin (having phenylene skeleton, biphenylene skeleton, etc.), naphthol aralkyl type epoxy resin (having phenylene skeleton, biphenylene skeleton, etc.) That), terpene-modified phenol type epoxy resin, triazine nucleus-containing epoxy resins, but are not limited thereto. These epoxy resins may be used alone or in combination.
For the purpose of improving the solder resistance of the semiconductor device, the amount of the inorganic filler in the epoxy resin composition is increased, and the obtained cured epoxy resin composition has low moisture absorption, low thermal expansion, high In order to achieve the strength, it is particularly preferable to use 30% by weight or more of a crystalline epoxy resin which exhibits crystallinity at room temperature and becomes a liquid having an extremely low viscosity when the melting point is exceeded.
[0011]
The phenolic resin used in the present invention includes all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in one molecule, and includes, for example, phenol novolak resin, cresol novolak resin, phenol aralkyl resin (phenylene skeleton, biphenylene Skeleton), naphthol aralkyl resin (having a phenylene skeleton, biphenylene skeleton, etc.), terpene-modified phenolic resin, dicyclopentadiene-modified phenolic resin, triphenolmethane-type phenolic resin, bisphenol compound, etc., but are not limited thereto. It is not done. These phenol resins may be used alone or in combination of two or more.
The equivalent ratio of the epoxy groups of all epoxy resins to the phenolic hydroxyl groups of all phenol resins is preferably 0.5 to 2.0, particularly preferably 0.7 to 1.5. If the ratio is outside the above range, the curability, the moisture resistance reliability and the like may be reduced.
[0012]
The curing accelerator used in the present invention can be a catalyst for a cross-linking reaction between an epoxy resin and a phenol resin. Examples of the curing accelerator include amines such as tributylamine and 1,8-diazabicyclo (5,4,0) undecene-7. Organic compounds such as triphenylphosphine and tetraphenylphosphonium / tetraphenylborate salts; and imidazole compounds such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or in combination.
[0013]
As the inorganic filler used in the present invention, those generally used in an epoxy resin composition for semiconductor encapsulation can be used, and examples thereof include fused silica, crystalline silica, alumina, silicon nitride, and aluminum nitride. Can be These inorganic fillers may be used alone or in combination.
When increasing the amount of the inorganic filler, fused silica is generally used. Fused silica can be used in either crushed or spherical form.However, in order to increase the amount of the fused silica and to suppress an increase in the melt viscosity of the epoxy resin composition, it is preferable to mainly use a spherical form. preferable. In order to further increase the content of the fused spherical silica, it is desirable to adjust the particle size distribution of the fused spherical silica to be wider. The inorganic filler that has been surface-treated with a silane coupling agent or the like in advance may be used.
[0014]
The disulfide compound containing no heterocyclic ring used in the present invention is a compound having a disulfide structure, improves the adhesion between the cured product of the resin composition and the lead frame, and is thus a semiconductor device formed of a cured product of the resin composition. To improve the humidity resistance and the reflow crack resistance of the semiconductor device in which the semiconductor device is sealed. The compound having a disulfide structure is particularly effective in improving the adhesion between the cured product of the resin composition and a non-copper lead frame (a silver-plated lead frame, a pre-pleating frame in which a nickel / palladium alloy is gold-plated). Therefore, when the lead frame is used, the reliability of the semiconductor device is greatly improved. Further, it is essential that the disulfide compound containing no heterocycle used in the present invention does not contain a heterocycle. Heterocycles contain many unstable bonds such as N—S bonds and N—C bonds, and may be decomposed by heat in a heat molding or soldering process, which may adversely affect adhesion. Therefore, a structure having a heterocyclic structure at the terminal of the disulfide structure has a problem in thermal stability.
The disulfide compound used in the present invention is not particularly limited, but is preferably a compound represented by the general formula (1). At both ends of the disulfide, an alkyl group or aryl group having 2 to 18 carbon atoms is preferable. If the molecular weight of the compound is large, the effect of improving the adhesion to the lead frame may be difficult to obtain. Further, in order to prevent volatilization due to heat during heat molding, the boiling point of the disulfide compound is preferably 175 ° C. or higher.
[0015]
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(In the formula, R1 and R2 are an alkyl group or an aryl group having 2 to 18 carbon atoms. R1 and R2 may be the same or different.)
[0016]
The amount of the disulfide compound containing no heterocyclic ring used in the present invention is not particularly limited, but is preferably 0.01 to 2% by weight based on the whole resin composition. If the value is below the lower limit, the effect of improving the adhesion may be weakened. If the value exceeds the upper limit, the strength of the molded product may be reduced and the reliability of the package may be impaired.
[0017]
The epoxy resin composition of the present invention comprises an epoxy resin, a phenol resin, an inorganic filler, a curing accelerator, and, if necessary, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and an aluminum / zirconium coupling. Agents, brominated epoxy resins, flame retardants such as antimony oxide and phosphorus compounds, inorganic ion exchangers such as bismuth oxide hydrate, coloring agents such as carbon black and red iron oxide, silicone oil, silicone rubber, etc. Various additives such as a releasing agent such as a low stress agent, a natural wax, a synthetic wax, a higher fatty acid and its metal salts or paraffin, and an antioxidant may be appropriately compounded.
[0018]
The epoxy resin composition of the present invention is prepared by mixing an epoxy resin, a phenol resin, an inorganic filler, a curing accelerator, and other additives using a mixer, and then kneading the mixture with a kneader such as a roll, a kneader, or an extruder. After cooling, it is obtained by grinding.
In order to manufacture a semiconductor device by encapsulating an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, it is sufficient to cure and mold by a molding method such as a transfer mold, a compression mold, and an injection mold.
[0019]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. The mixing unit is parts by weight.
Example 1
[0020]
8.2 parts by weight of an epoxy resin represented by the formula (2) (softening point: 58 ° C., epoxy equivalent: 272, hereinafter referred to as epoxy resin 1)

[0021]
6.0 parts by weight of a phenolic resin represented by the formula (3) (softening point: 107 ° C., hydroxyl equivalent: 200, hereinafter referred to as phenolic resin 1)

[0022]
84.9 parts by weight of fused spherical silica (average particle size 28 μm) 0.2 parts by weight of 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU)
0.2 parts by weight of di-t-octyl disulfide (Tokyo Kasei, primary reagent) represented by the formula (4)

[0024]
Carnauba wax 0.2 parts by weight Carbon black 0.3 parts by weight is mixed using a mixer, then kneaded using two rolls having a surface temperature of 90 ° C. and 25 ° C., cooled and pulverized to obtain an epoxy resin composition. Got. The properties of the obtained epoxy resin composition were evaluated by the following methods. Table 1 shows the results.
[0025]
Evaluation method Spiral flow: Using a mold for spiral flow measurement in accordance with EMMI-1-66, the measurement was performed at a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 120 seconds. The unit is cm.
Adhesion strength: Using a transfer molding machine, under the conditions of a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds, 10 pieces of 2 mm × 2 mm × 2 mm adhesion strength test pieces on a lead frame per level. Molded. Two types of lead frames were used: a copper frame with silver plating (frame 1) and a NiPd alloy frame with gold plating (frame 2). Then, the shear strength between the cured product of the epoxy resin composition and the frame was measured using an automatic shear strength measuring device (PC2400, manufactured by DAGE). Table 1 shows the average value of the shear strength of the ten test pieces. The unit is N / mm ² .
Solder resistance: 176-pin LQFP package (package size is 24 × 24 mm, thickness is 2.0 mm, silicon chip size is 8.0 × 8.0 mm, lead frame is 176 pin pre-plating frame, NiPd alloy is Au plated Was subjected to transfer molding under the conditions of a mold temperature of 175 ° C., an injection pressure of 9.3 MPa, and a curing time of 120 seconds, and was post-cured at 175 ° C. for 8 hours. The obtained package was humidified for 168 hours in an environment of 85 ° C. and 60% relative humidity. Thereafter, this package was immersed in a solder bath at 260 ° C. for 10 seconds. The soldered package was observed using an ultrasonic flaw detector, and the rate of occurrence of peeling at the interface between the chip (SiN-coated product) and the cured product of the epoxy resin composition [(number of peeling-off packages) / (The total number of packages) × 100] in%.
[0026]
Examples 2 to 6, Comparative Examples 1 to 3
According to the formulation in Table 1, an epoxy resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 1 shows the results. Table 2 shows details of the epoxy resin and the phenol resin used. The disulfide compounds used in Examples 1 and 2 are shown below.
[0027]
Di-t-dodecyl disulfide represented by the formula (5) (Tokyo Kasei)
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[0028]
Diphenyl disulfide represented by the formula (6) (Tokyo Kasei)
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[0029]
Dibenzyl disulfide represented by formula (7) (Tokyo Kasei)
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[0030]
Di-2-benzothiazolyl disulfide represented by the formula (8) (Tokyo Kasei)
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[0031]
[Table 1]

[0032]
[Table 2]

[0033]
According to Example 1, it was found that the epoxy resin composition to which the disulfide compound was added had high adhesion strength to the lead frame and excellent reliability. Further, although there is a difference depending on the kind of the resin in Example 2, the adhesion strength is increased by adding the disulfide compound. Further, according to Example 3, the effect was obtained even when the alkyl chain at the disulfide terminal was lengthened to some extent. According to Examples 4 and 5, it was found that those having a benzene ring at both ends of disulfide can obtain the same effect as the alkyl chain. In Example 6, a large amount of the disulfide compound was added. However, although the fluidity was low, the results obtained were excellent in adhesion strength and reliability. Comparative Examples 1 and 2 were systems in which no disulfide compound was added, but the results were low in adhesion strength and low in reliability regardless of the type of resin. Comparative Example 3 uses 2-benzothiazolyl disulfide, which is a disulfide compound containing a heterocyclic ring, but results in reduced adhesion strength and reliability.
[0034]
【The invention's effect】
A semiconductor device obtained by using the epoxy resin composition of the present invention has a high adhesion strength to a non-copper lead frame and has excellent reliability.

Claims (4)

An epoxy resin for semiconductor encapsulation comprising (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, and (E) a disulfide compound containing no heterocycle. Composition. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the disulfide compound not containing a heterocycle is a compound represented by the general formula (1).

(In the formula, R1 and R2 are an alkyl group or an aryl group having 2 to 18 carbon atoms. R1 and R2 may be the same or different.) 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the disulfide compound containing no heterocycle is contained in an amount of 0.01 to 2% by weight based on the resin composition. 4. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to claim 1.