JP2003206393A - Epoxy resin molding material and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing of semiconductors having good fluidity in molding, high resistance to the temperature cycle and high soldering resistance. <P>SOLUTION: The composition contains (A) an epoxy resin, (B) a phenol resin, (C) a hardening accelerator, (D) an inorganic filler and (E) rubber particles having epoxy equivalents of 24,000 or higher. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation excellent in moldability and reliability, and a semiconductor device using the same.

[0002]

2. Description of the Related Art In recent market trends of miniaturization, weight reduction, and high performance of electronic devices, the integration of semiconductor elements has been increasing year by year, the size of semiconductor elements has increased, and wiring has become finer. When such a semiconductor element is sealed with an epoxy resin composition, since the cured product of the epoxy resin composition comes into direct contact with the semiconductor element, strain stress is caused by expansion and contraction of the cured product of the epoxy resin composition due to temperature cycle. This causes problems such as wiring deviation, cutting of bonding wires, and destruction of semiconductor elements. For these problems, it is necessary to reduce the elastic modulus of the cured product of the epoxy resin composition and impart flexibility to the cured product of the epoxy resin composition. In the current situation where surface mounting of semiconductor devices is becoming more common, semiconductor devices that have absorbed moisture are exposed to high temperatures during solder processing, and the semiconductor devices may crack due to the explosive stress of vaporized water vapor, or When peeling occurs at the interface between the element or the lead frame and the cured product of the epoxy resin composition, defects that greatly impair electrical reliability occur, and prevention of these defects, that is, improvement of solder resistance is also a major issue. Has become.

In order to improve the solder resistance, the epoxy resin composition contains a large amount of an inorganic filler,
We are trying to reduce the moisture absorption, the thermal expansion and the strength of semiconductor devices. Therefore, as the resin component, a low-viscosity type resin or a resin that is a crystalline solid at room temperature and becomes a liquid with an extremely low viscosity when the temperature exceeds the melting point is used. Techniques have been proposed for preventing a decrease in fluidity of a resin composition during molding. However, in an epoxy resin composition produced by heating and kneading each component, in a cured product of an epoxy resin composition containing a large amount of an inorganic filler, the elastic modulus increases with the increase of the strength, so that the temperature cycle As a result, strain stress increases, which causes a problem in temperature cycle resistance.

In order to achieve both temperature cycle resistance and solder resistance in this way, it is necessary to suppress an increase in elastic modulus even in a system containing a large amount of inorganic filler. As one of the concrete methods, a method of adding various rubber particles in order to impart low stress characteristics has been conventionally known. However, with conventional rubber particles, the cohesive force of the particles is strong and the particles are not uniformly dispersed during kneading, so that the epoxy resin composition becomes non-uniform, resulting in large variations in properties. Further, if the agglomerates of the rubber particles are large, the viscosity in the molten state may increase and the fluidity may decrease, or defects such as cracks originating from the agglomerates during the soldering process may occur. Therefore, it has been desired to develop an epoxy resin composition that satisfies the requirements of fluidity, temperature cycle resistance, and solder resistance.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent fluidity during molding, temperature cycle resistance and solderability, and a semiconductor device using the same. Is provided.

[0006]

The present invention provides [1]
(A) Epoxy resin, (B) Phenolic resin, (C) Curing accelerator, (D) Inorganic filler, and (E) Epoxy equivalent epoxy resin composition for semiconductor encapsulation of 24,000 or more. Thing, [2] Epoxy equivalent 2
4000 or more rubber particles, the epoxy resin composition for semiconductor encapsulation according to the item [1], wherein [3] the total epoxy resin composition has at least one cyano group in the molecule,
The epoxy resin composition for semiconductor encapsulation according to the item [1] or [2], which has an acetone insoluble content of 0.01% by weight or less.
[4] A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to any one of the items [1] to [3].

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having two or more epoxy groups in one molecule, and examples thereof include hydroquinone type epoxy resin, bisphenol A type epoxy resin and bisphenol. F type epoxy resin, biphenyl type epoxy resin, stilbene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthol novolac type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin, di Cyclopentadiene-modified phenol type epoxy resin, phenol aralkyl type epoxy resin (having phenylene skeleton, biphenylene skeleton, etc.), naphthol aralkyl type epoxy resin (phenylene skeleton, bifene Having a vinylene skeleton or the like), 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 compounding amount of the inorganic filler in the epoxy resin composition is increased, and the cured product of the obtained epoxy resin composition has low moisture absorption, low thermal expansion, and high To achieve strength, the crystalline epoxy resin, which exhibits crystallinity at room temperature and becomes an extremely low-viscosity liquid when it exceeds the melting point, accounts for 30% by weight of the total epoxy resin.
It is particularly preferable to use the above.

The phenol resin used in the present invention refers to all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in one molecule.
Phenol novolac resin, cresol novolac resin, phenol aralkyl resin (having phenylene skeleton, biphenylene skeleton, etc.), naphthol aralkyl resin (having phenylene skeleton, biphenylene skeleton, etc.), terpene modified phenol resin, dicyclopentadiene modified phenol resin, triphenol Examples thereof include methane type resins and bisphenol compounds, but are not limited thereto. These phenol resins may be used alone or in combination of two or more kinds. These phenol resins do not limit the molecular weight, softening point, hydroxyl group equivalent, etc., but phenol resins having a softening point of 90 ° C. or lower and a relatively low viscosity are preferable. 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.
It is 5. When it is out of the range of 0.5 to 2.0, curability,
There is a possibility that the humidity resistance and the like will be reduced.

The curing accelerator used in the present invention includes
A substance that can serve as a catalyst for a crosslinking reaction between an epoxy resin and a phenol resin, for example, tributylamine, 1,8-
Examples include amine compounds such as diazabicyclo (5,4,0) undecene-7, organic phosphorus compounds such as triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salts, and imidazole compounds such as 2-methylimidazole. It is not limited to these. These curing accelerators may be used alone or in combination.

Examples of the inorganic filler used in the present invention include fused silica, crystalline silica, alumina, silicon nitride and aluminum nitride. These inorganic fillers may be used alone or in combination. When the amount of the inorganic filler to be blended is increased, fused silica is generally used. The fused silica can be used in either a crushed form or a spherical form, but in order to increase the blending amount of the fused silica and suppress the increase in the melt viscosity of the epoxy resin composition, it is preferable to use the spherical form. preferable. Further, in order to increase the blending amount of the fused spherical silica, it is desirable to adjust so that the particle size distribution of the fused spherical silica becomes wider. As the inorganic filler, one that has been surface-treated with a silane coupling agent or the like in advance may be used.

The epoxy equivalent used in the present invention is 240.
Examples of the rubber particles of 00 or more include, but are not limited to, butadiene styrene rubber, butadiene acrylonitrile rubber, polyurethane rubber, polyisoprene rubber, acrylic rubber, fluororubber, and silicone rubber. Among these, butadiene acrylonitrile rubber having at least one cyano group in the molecule is preferable in order to improve the compatibility with the resin component. The acrylonitrile component has high compatibility with the resin component and is easily dispersed. These may be used alone or in combination. In addition to the epoxy group, an organic substituent such as a methyl group or a phenyl group, and an organic substituent having a C, O, N, S atom or the like in its molecule in order to impart an affinity with the resin component. You may have. Examples of the organic substituent having C, O, N, S atoms and the like include vinyl group, phenethyl group, hydroxy group, carboxyl group, acryl group, alkoxy group, polyether group, caprolactone group, amino group, ureido group, isocyanate. Group, mercapto group and the like, but not limited thereto.

The epoxy equivalent of the rubber particles used in the present invention is 24,000 or more. If it is less than 24000, the affinity between the resin component and the rubber particles becomes too strong, and the fluidity of the epoxy resin composition is lowered. On the other hand, if the rubber particles do not contain an epoxy group, the particles are hard to disperse in the resin component and the aggregation of the rubber particles becomes strong. If the rubber particles are uniform and vary in characteristics, and the rubber particles are not sufficiently dispersed and aggregated, the viscosity in the molten state increases and the fluidity decreases, and cracks originate from the aggregates of the rubber particles during soldering. And other defects occur.
The maximum particle size of the rubber particle aggregate of the present invention is 108
It is preferably not more than μm, and if it exceeds 108 μm, the aggregate may block the flow path at the time of thermoforming, which is not preferable.
In the rubber particles used in the present invention, the primary particles are agglomerated with each other, but the agglomeration is easily broken at the time of kneading, and the fluidity of the obtained epoxy resin composition is not adversely affected. The average particle diameter of the primary particles of the rubber particles of the present invention is preferably 50 μm or less, and when it exceeds 50 μm, the fluidity of the epoxy resin composition is lowered and the strength of the cured product is also lowered, which is not preferable.

As the method for measuring the epoxy equivalent, the cetyltrimethylammonium bromide-perchloric acid method is used. In this method, 80 ml of trimethylketone and 10 ml of glacial acetic acid were added to and dissolved in a sample containing an epoxy group of 0.6 to 0.9 g / eq, about 1 g of cetyltrimethylammonium bromide was added, and crystal violet indicators 2-3 were added.
Add drops. Titrate with 0.1N perchloric acid-glacial acetic acid solution,
The end point is the point where the color changes from blue green to pink.

The amount of the rubber particles used in the present invention is preferably 0.1 to 5% by weight based on the total epoxy resin composition. If it is less than 0.1% by weight, the effect of elastic modulus reduction may not be obtained, and if it exceeds 5% by weight, the strength of the cured product may be reduced, or the water absorption rate may be increased, resulting in a decrease in solder resistance. It is not preferable because there is. Further, if the acetone insoluble content in the obtained epoxy resin composition is 0.01% by weight or less in the total epoxy resin composition, it does not adversely affect the fluidity, but if it exceeds 0.01% by weight, the fluidity is deteriorated. Is significantly reduced, which is not preferable. The acetone insoluble matter is considered to be rubber particles or a resin gelled product, but if they are contained in the epoxy resin, they block the flow path during heat molding.

The content of the aggregate of rubber particles in the epoxy resin composition is measured, and the acetone insoluble content method is used. About 100 g of the epoxy resin composition was precisely weighed and dissolved in 200 g of acetone, and shaken with a shaker for 20 minutes, and the acetone solution of the epoxy resin composition was sieved with a 108 μm sieve, and the weight of the insoluble matter remaining on the sieve was measured. Measured and expressed in% by weight. Moreover, this insoluble matter is observed with an optical microscope. This insoluble content includes, in addition to rubber particles, an epoxy resin gelation product and the like.

Other flexibility-imparting agents may be added as long as the characteristics of the rubber particles of the present invention are not impaired. Examples of the flexibility-imparting agent that can be used in combination include, but are not limited to, liquid synthetic rubbers such as liquid organopolysiloxane and liquid polybutadiene.

The epoxy resin composition of the present invention comprises (A)-
The component (E) is an essential component, but if necessary, a brominated epoxy resin, a flame retardant such as antimony oxide, a silane coupling agent, a release agent such as a natural wax and a synthetic wax,
You may mix | blend various additives, such as a coloring agent, such as carbon black, suitably. The epoxy resin composition of the present invention comprises (A)-
It can be obtained by mixing the component (E), other additives and the like with a mixer or the like, then kneading by heating with a heating kneader or a heat roll, cooling and pulverizing. In order to manufacture a semiconductor device by sealing an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, it may be cured and molded by a molding method such as a transfer mold, a compression mold, an injection mold.

[0018]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. Example 1 Biphenyl type epoxy resin (Japan Epoxy Resin Co., Ltd. YX4000 H, melting point 105 ° C., epoxy equivalent 195) 7.8 parts by weight Phenol aralkyl resin (Mitsui Chemicals, Inc. XLC-LL, softening point 79 ° C.) , Hydroxyl equivalent 175) 7.0 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 parts by weight spherical fused silica 82.5 parts by weight Rubber particles 1 (epoxy group Butadiene acrylonitrile rubber having: Epoxy equivalent 30900) 2.0 parts by weight Carnauba wax 0.2 parts by weight Carbon black 0.3 parts by weight are mixed using a mixer, and then the surface temperature is 90 ° C. and 2
The mixture was kneaded using two rolls at 5 ° C., cooled and pulverized to obtain an epoxy resin composition. The characteristics of the obtained epoxy resin composition were evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a mold for spiral flow measurement according to EMMI-1-66, mold temperature 175 ° C.
The injection pressure was measured at 6.9 MPa and the curing time was 120 seconds. The unit is cm. Bending strength: The bending strength at 25 ° C or 240 ° C is determined by JIS
It was measured according to K 6911. The unit is MPa. Flexural modulus: JI is the flexural modulus at 25 ° C or 240 ° C
It was measured according to SK 6911. The unit is MPa. Temperature cycle resistance: 160-pin LQFP package (package size 24 × 24 mm, thickness 2.0 mm, silicon chip size 8.0 × 8.0 mm, lead frame made of 42 alloy), mold temperature 175 ° C., Transfer molding was performed at an injection pressure of 9.3 MPa and a curing time of 120 seconds, and post-curing was performed at 175 ° C. for 8 hours. The obtained package was repeatedly treated in an environment of −60 ° C./30 minutes to 150 ° C./30 minutes, and the presence or absence of external cracks was observed. The time when external cracks were generated in 50% or more of the obtained packages was measured and shown as "50% failure occurrence time". The unit is hr. Solder resistance: 160-pin LQFP package (package size 24 x 24 mm, thickness 2.0 mm, silicon chip size 8.0 x 8.0 mm, lead frame made of 42 alloy), mold temperature 175 ° C injection Pressure 9.3
Transfer molding at MPa, curing time 120 seconds,
Post-cure at 175 ° C. for 8 hours. The obtained package was left in an environment of 85 ° C. and 60% relative humidity for 168 hours, and the weight difference before and after moisture absorption was divided by the weight before moisture absorption to obtain the moisture absorption rate, which was expressed in%. Then package this at 240 ℃
It was dipped in the solder bath for 10 seconds. The external cracks were observed with a microscope, and the crack occurrence rate [(number of cracked packages) / (total number of packages) × 100] was expressed in%.
Also, by observing this package using an ultrasonic flaw detector, 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 peeled packages) / (Total packages) (Number) × 100] is expressed in%. Acetone insoluble matter: According to the above method.

Examples 2-5, Comparative Examples 1-5 According to the formulations shown in Table 1, epoxy 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 Table 1. Table 2 shows the characteristics of the rubber particles used in Examples and Comparative Examples. Rubber particles 1 to 6 are manufactured by JSR Corporation.
XSA series, rubber particles 7 are Septon 4033 manufactured by Kuraray Co., Ltd.

[0021]

[Table 1]

[0022]

[Table 2]

The epoxy resin compositions of Examples 1 to 5 are excellent in fluidity (spiral flow) at the time of molding, low elastic modulus and solder resistance, and also have a small content of acetone insoluble matter, so that they are rubber particles. There is no aggregation. The fluidity of Comparative Examples 1 to 3 is inferior to that of the Examples, and the rubber particles are agglomerated from the acetone insoluble matter and microscopic observation. In Comparative Example 4, rubber particles not containing an epoxy group and a cyano group were blended, but not only the fluidity, low elastic modulus and solder resistance were inferior to those in Examples, but also acetone insoluble matter and a microscope were used. From the observation, rubber particles are aggregated. Comparative Example 5 does not contain rubber particles, and thus has a very high elastic modulus.

[0024]

The epoxy resin composition of the present invention is excellent in fluidity at the time of molding and has both high strength and low elastic modulus. A semiconductor device using the same has a high temperature cycle resistance and Excellent in soldering resistance.

Continued front page    F-term (reference) 4J002 AC032 AC062 AC072 BD122                       BG042 CD031 CD041 CD051                       CD061 CD071 CK022 CP032                       DF017 DJ007 DJ017 EN046                       EU116 EU136 EW016 EW176                       FB087 FD017 FD130 FD156                       FD160 GJ01 GQ05                 4J036 AA01 AA04 AA05 BA02 DC05                       DC41 DC46 DD07 FA02 FA03                       FA04 FA05 FB01 FB03 FB05                       FB07 FB10 FB16 HA12 JA07                       KA06                 4M109 AA01 CA21 EB19 EC05 EC20

Claims (4)

[Claims] 1. A semiconductor encapsulation containing (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, and (E) an epoxy equivalent of 24,000 or more rubber particles. Stopping epoxy resin composition. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the rubber particles having an epoxy equivalent of 24000 or more have at least one cyano group in the molecule. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the total epoxy resin composition has an acetone insoluble content of 0.01% by weight or less. 4. A semiconductor device, comprising a semiconductor element encapsulated with the epoxy resin composition according to claim 1.