JP5153050B2 - Epoxy resin composition and semiconductor device - Google Patents

Description

  The present invention relates to an epoxy resin composition for semiconductor encapsulation excellent in fluidity, curability, moldability, and solder resistance, and a semiconductor device using the same.

Transfer molding of an epoxy resin composition as a sealing method for semiconductor elements such as IC and LSI is suitable for mass production at low cost and has been used for a long time. Improvements have been made to improve properties. However, due to the recent trend toward smaller, lighter, and higher performance electronic devices, higher integration of semiconductors has progressed year by year, and semiconductor device epoxy has been promoted as surface mounting of semiconductor devices has been promoted. The demand for resin compositions has become increasingly severe. For this reason, the problem which cannot be solved with the conventional epoxy resin composition has also come out.
The biggest problem is that by adopting surface mounting, the semiconductor device is suddenly exposed to a high temperature of 200 ° C. or higher in the solder dipping or solder reflow process, and the moisture when moisture absorbed explosively vaporizes the semiconductor device. This is a phenomenon in which reliability is significantly reduced due to the occurrence of cracks or peeling at the interface between various plated joints on the semiconductor element, lead frame, and inner lead and the cured product of the epoxy resin composition. .

  In order to improve reliability degradation 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, improve solder resistance, There is a technique of using a low melt viscosity resin to maintain a high fluidity at a low viscosity during molding (see, for example, Patent Document 1). By using this method, the solder crack resistance is considerably improved. However, as the filling rate of the inorganic filler is increased, the fluidity is sacrificed and voids are easily generated in the package. Thus, a technique for maintaining fluidity by using fillers having different average particle diameters has been proposed (for example, see Patent Document 2). However, a sufficiently good epoxy resin composition for semiconductor encapsulation can be obtained. Not reached.

JP-A 64-65116 (pages 2 to 7) JP-A-8-20673 (pages 2 to 6)

  The present invention provides an epoxy resin composition for semiconductor encapsulation having excellent fluidity and moldability and high heat strength characteristics, and a semiconductor device excellent in solder resistance.

The present invention
[1] (A) epoxy resin, (B) phenol resin, (C) curing accelerator, (D) fused silica having an average particle size of 5 to 40 μm, and (E) average particle size of 0.1 to 3 μm, An epoxy resin composition for encapsulating a semiconductor , wherein the surface has a silanol group density of greater than 2.1 / nm ² and 4.0 or less / nm ² , wherein the fused silica (D) The fused silica (E) has a blending ratio of (D) / (E) = 97/3 to 75/25, and the blending ratio of (D) and (E) is 85 in the total epoxy composition. Epoxy resin composition for semiconductor encapsulation, which is ˜94% by weight,
[2] The silanol group density on the surface of the fused silica (D) having an average particle size of 5 to 40 μm is greater than 1.0 / nm ² and not greater than 4.0 / nm ² [1] The epoxy resin composition for semiconductor encapsulation according to Item,
[ 3 ] A semiconductor device comprising a semiconductor element sealed using the epoxy resin composition for semiconductor sealing according to [1] or [2] ,
It is.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor device excellent in the fluidity | moldability and moldability and the semiconductor resin excellent in the soldering resistance and the epoxy resin composition for semiconductor sealing which has the characteristic with a high heat | fever intensity | strength can be obtained.

The present invention includes fluidity by including an epoxy resin, a phenolic resin, a curing accelerator, fused silica having a specific average particle size, and fine fused silica having a specific surface silanol group density at a specific average particle size, It is possible to obtain an epoxy resin composition for semiconductor encapsulation and a semiconductor device excellent in solder resistance, which have excellent moldability and high thermal strength properties.
Hereinafter, the present invention will be described in detail.

  The epoxy resin used in the present invention is a monomer, oligomer, or polymer in general having two or more epoxy groups in one molecule, and its molecular weight and molecular structure are not particularly limited. For example, biphenyl type epoxy resin, bisphenol type Epoxy resin, stilbene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, triazine nucleus-containing epoxy resin, dicyclopentadiene modified phenol type epoxy resin And phenol aralkyl type epoxy resins (having a phenylene skeleton, a biphenylene skeleton, etc.) and the like, and these may be used alone or in combination.

  The phenol resin used in the present invention is a monomer, oligomer, or polymer in general having two or more phenolic hydroxyl groups in one molecule, and its molecular weight and molecular structure are not particularly limited. For example, phenol novolak resin, cresol novolak Resin, dicyclopentadiene-modified phenol resin, terpene-modified phenol resin, triphenolmethane type resin, phenol aralkyl resin (having a phenylene skeleton, biphenylene skeleton, etc.), etc. These may be used alone or in combination. .

  As a compounding quantity of an epoxy resin and a phenol resin, it is preferable that the ratio of the number of epoxy groups of all epoxy resins and the number of phenolic hydroxyl groups of all phenol resins is 0.8 to 1.3. There is a possibility that the curability of the composition is lowered, the glass transition temperature of the cured product is lowered, and the moisture resistance reliability is lowered.

  The curing accelerator used in the present invention is not particularly limited as long as it accelerates the reaction between an epoxy group and a phenolic hydroxyl group. For example, 1,8-diazabicyclo (5,4,0) undecene-7 is used. Diazabicycloalkene and its derivatives, amine compounds such as tributylamine and benzyldimethylamine, imidazole compounds such as 2-methylimidazole, organic phosphines such as triphenylphosphine and methyldiphenylphosphine, tetraphenylphosphonium tetraphenylborate, Tetraphenylphosphonium ・ tetrabenzoic acid borate, tetraphenylphosphonium ・ tetranaphthoic acid borate, tetraphenylphosphonium ・ tetranaphthoyloxyborate, tetraphenylphosphonium ・ tetranaphthyloxy Tetra-substituted phosphonium tetra-substituted borate borate, and the like. These may be used in combination of two or more be used one kind alone.

  As the fused silica used in the present invention, fused silica (D) having an average particle size of 5 to 40 μm and fused silica (E) having an average particle size of 0.1 to 3 μm are used in combination. This is because fine particles are sandwiched in the gaps between the coarse particles, thereby serving as a so-called “roller” and improving the fluidity of the epoxy resin composition.

In the fused silica (D) having an average particle diameter of 5 to 40 μm used in the present invention, sufficient fluidity cannot be obtained when the average particle diameter is below the lower limit value, and solder resistance is deteriorated when the upper limit value is exceeded. In addition, in fused silica (E) having an average particle size of 0.1 to 3 μm, if the average particle size is below the lower limit, it becomes difficult to suppress aggregation between the particles. Can't play a role. The average particle diameter of the inorganic filler used in the present invention is measured using a laser particle size distribution meter (SALD-7000, manufactured by Shimadzu Corporation).

The specific surface area of fused silica (D) having an average particle size of 5 to 40 μm used in the present invention is not particularly limited, but is preferably 0.8 to 3.5 m ² / g. If the lower limit is not reached, solder resistance may be reduced, and if the upper limit is exceeded, sufficient fluidity may not be obtained. The specific surface area of fused silica (E) having an average particle size of 0.1 to 3 μm is not particularly limited, but is preferably 3.5 to 7.0 m ² / g. If the lower limit is not reached, solder resistance may be reduced, and if the upper limit is exceeded, sufficient fluidity may not be obtained. The specific surface area of the inorganic filler used in the present invention is measured using a monosorb MS-17 manufactured by Yuasa Ionics Co., Ltd.

The silanol group density on the surface of the fused silica (E) having an average particle diameter of 0.1 to 3 μm used in the present invention must be larger than 2.1 / nm ² and not larger than 4.0 / nm ^2. is there. Below the lower limit, the cohesive force between the particles becomes strong, and a sufficiently dispersed state cannot be obtained. Moreover, since there are few reaction points, sufficient intensity | strength cannot be obtained and solder resistance deteriorates. If the upper limit is exceeded, the hydrophilicity is too strong, so the familiarity with the resin will be poor and the fluidity will tend to deteriorate, and the fused silica will easily absorb moisture, and the epoxy resin composition cured when heated Reduce the strength. There are no particular restrictions on the method for controlling the silanol group density on the surface of the fused silica, and there are many points that are not well understood. The silanol group density may be increased by heating, or the silanol group density may be decreased by heat treatment.

The silanol group density on the surface of the fused silica (D) having an average particle diameter of 5 to 40 μm used in the present invention is not particularly limited, but is larger than 1.0 / nm ² and not larger than 4.0 / nm ^2. It is preferable that Below the lower limit, there are few reaction points, so sufficient strength may not be obtained, and solder resistance may be deteriorated. When the upper limit is exceeded, hydrophilicity is too strong, so the familiarity with the resin will deteriorate. The fluidity tends to deteriorate, and the fused silica tends to absorb moisture, which may reduce the strength of the cured epoxy resin composition when heated.

The surface silanol group density of the fused silica used in the present invention is measured in the following manner. A large excess of hexamethyldisilazane is added to fused silica, and the mixture is allowed to stand at 200 ° C. for 2 hours to completely react silanol groups on the fused silica surface with hexamethyldisalazane, and the residue is removed to prepare a sample. After that, the sample was put in a crucible and allowed to stand at 700 ° C. for 3 hours to be sufficiently incinerated. The amount of decrease was calculated as a methyl group, and the amount of hexamethyldisilazane reacted with the silanol group on the fused silica surface was determined. Calculate the density. In other words, the calculation method is
Silanol group density = reduction amount ÷ {molecular weight of (CH ₃ ) ₃ } × Avocado number ÷ surface area ,
It is.

  The blending of the fused silica used in the present invention is not particularly limited, but the ratio of fused silica (D) having an average particle size of 5 to 40 μm and fused silica (E) having an average particle size of 0.1 to 3 μm is It is preferable that (D) / (E) = 97/3 to 75/25. If the ratio of the fused silica having an average particle size of 0.1 to 3 μm is less than the lower limit value, the fluidity is lowered, and if it exceeds the upper limit value, problems such as a decrease in solder resistance accompanying an increase in moisture absorption rate are preferable. Absent. The blending ratio of both the fused silica (D) and the fused silica (E) is preferably 84 to 94% by weight in the total epoxy resin composition. If the lower limit is not reached, the solder resistance decreases with an increase in the moisture absorption rate. If the upper limit is exceeded, problems such as deformation of the gold wire and pad shift are not preferable.

In the epoxy resin composition of the present invention, a coupling agent is used as necessary in order to enhance the adhesion between the fused silica and the resin. A coupling agent refers to the coupling agent currently used for the surface treatment of an inorganic substance normally. Examples include aminosilane, epoxysilane, mercaptosilane, alkylsilane, ureidosilane, vinylsilane, and other silane coupling agents, titanate coupling agents, aluminum coupling agents, aluminum / zirconium coupling agents, etc. Examples of the silane coupling agent include aminosilane, epoxy silane, mercaptosilane, and ureidosilane. Examples of these include γ-aminopropyltriethoxysilane, γ-amino. Propyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-phenylγ-aminopropyltriethoxysilane, N -Phenyl γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, N-6- (aminohexyl) 3-aminopropyltrimethoxysilane, N- (3- (trimethoxysilyl) Propyl) -1,3-benzenedimethanane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β- (3,4 epoxy cyclohexyl) ) Ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, etc. These may be used alone or in combination, and the coupling agent may be water or in advance. Depending on the conditions, acid or alkali may be added and hydrolyzed.
The coupling agent is considered to exhibit its effect by reacting with the silanol groups on the surface of the fused silica and adhering to the surface of the fused silica. In addition, it is considered that the coupling agent molecules self-condensate from the coupling agent molecule fixed by reacting with the silanol group to cover the surface of the fused silica.

The epoxy resin composition of the present invention comprises the components (A) to (E) as essential, and a coupling agent is added as necessary. In addition, a colorant such as carbon black, crystalline silica, talc, Inorganic fillers such as alumina, silicon nitride and aluminum nitride, release agents such as natural wax and synthetic wax, and low stress additives such as rubber, brominated epoxy resin and antimony trioxide, aluminum hydroxide, magnesium hydroxide, Additives such as flame retardants such as zinc borate, zinc molybdate, and phosphazene may be appropriately blended.
In addition to the components (A) to (E), the epoxy resin composition of the present invention is sufficiently melted with a hot roll or a kneader after thoroughly mixing the additives to be added as necessary using a mixer or the like. It is obtained by kneading, pulverizing after cooling.
The epoxy resin composition of the present invention is used to encapsulate various electronic components such as semiconductor elements, and to manufacture semiconductor devices by conventional molding methods such as transfer molding, compression molding, and injection molding. do it.

Examples of the present invention are shown below, but the present invention is not limited thereto. The blending ratio is parts by weight.
In addition, it shows below about the content of the fused silica used by the Example and the comparative example.

Fused silica 1 (average particle size 24 μm, specific surface area 2.2 m ² / g, surface silanol group density 1.9 / nm ² )
Fused silica 2 (average particle size 29 μm, specific surface area 2.0 m ² / g, surface silanol group density 2.7 / nm ² )
Fused silica 3 (average particle size 38 μm, specific surface area 1.2 m ² / g, surface silanol group density 3.5 / nm ² )
Fused silica 4 (average particle size 13 μm, specific surface area 3.2 m ² / g, surface silanol group density 1.3 / nm ² )

Fused silica 5 (average particle size 0.5 μm, specific surface area 4.8 m ² / g, surface silanol group density 2.4 pcs / nm ² )
Fused silica 6 (average particle size 0.6 μm, specific surface area 5.1 m ² / g, surface silanol group density 3.7 / nm ² )
Fused silica 7 (average particle size 1.8 μm, specific surface area 3.8 m ² / g, surface silanol group density 2.2 / nm ² )
Fused silica 8 (average particle size 1.5 μm, specific surface area 4.4 m ² / g, surface silanol group density 3.6 / nm ² )
Fused silica 9 (average particle size 0.3 μm, specific surface area 6.7 m ² / g, surface silanol group density 2.5 / nm ² )
Fused silica 10 (average particle size 2.4 μm, specific surface area 3.6 m ² / g, surface silanol group density 2.3 / nm ² )
Fused silica 11 (average particle size 0.5 μm, specific surface area 5.8 m ² / g, surface silanol group density 1.9 / nm ² )
Fused silica 12 (average particle size 0.5 μm, specific surface area 5.6 m ² / g, surface silanol group density 4.3 / nm ² )
Fused silica 13 (average particle size 1.6 μm, specific surface area 4.3 m ² / g, surface silanol group density 1.8 / nm ² )

Example 1
Epoxy resin 1: manufactured by Japan Epoxy Resin Co., Ltd., YX-4000, epoxy equivalent 190 g / eq, melting point 105 ° C., hereinafter referred to as E-1. 56.0 parts by weight Phenol resin 1: manufactured by Mitsui Chemicals, Inc., XLC-LL, hydroxyl group equivalent 165 g / eq, softening point 79 ° C., hereinafter referred to as H-1. 48.0 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU)
5.0 parts by weight fused silica 1 780.0 parts by weight fused silica 5 100.0 parts by weight Coupling agent (γ-glycidoxypropyltrimethoxysilane) 3.0 parts by weight Carbon black 3.0 parts by weight Carnauba wax 5 0.0 parts by weight were mixed, kneaded at 95 ° C. for 8 minutes using a hot roll, cooled and pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a spiral flow measurement mold according to EMMI-1-66, measurement was performed at a mold temperature of 175 ° C., a pressure of 6.9 MPa, and a curing time of 120 seconds. The unit is cm.

  Bending strength during heating / Bending elastic modulus during heating: Measured according to the test conditions of JIS K 6911 (5.17.1 molding material). A test piece (length 80 mm, height 4 mm, width 10 mm) was molded using a transfer molding machine at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa and a curing time of 120 seconds, and post-cured at 175 ° C. for 8 hours. And created. This test piece was placed on a measurement stand (64 mm distance between supporting points), preheated in a bath maintained at 260 ° C. for 6 minutes, and then measured. The unit is MPa.

  Solder crack resistance: Using a low-pressure transfer molding machine, 80pQFP (Cu frame, chip size 6.0 mm × 6.0 mm) was molded at a molding temperature of 175 ° C., a pressure of 8.3 MPa, and a curing time of 120 seconds. After heat treatment at 175 ° C. for 8 hours, a humidification treatment was performed at 85 ° C. and a relative humidity of 85% for 120 hours, followed by an IR reflow treatment at 260 ° C. Peeling and cracks inside the package were confirmed with an ultrasonic flaw detector. The number of defective packages among the 10 packages is shown.

Examples 2-8, Comparative Examples 1-4
According to the composition of 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. The results are shown in Table 1.
The raw materials used other than Example 1 are shown below.

Epoxy resin 2: manufactured by Nippon Kayaku Co., Ltd., NC3000P, softening point 58 ° C., epoxy equivalent 273, hereinafter referred to as E-2.
Phenol resin 2: manufactured by Meiwa Kasei Co., Ltd., MEH-7851SS, softening point 107 ° C., hydroxyl group equivalent 204, hereinafter referred to as H-2.

  According to the present invention, it is possible to obtain an epoxy resin composition for semiconductor encapsulation having excellent fluidity and moldability and high thermal strength characteristics. Therefore, a semiconductor device that requires a higher level of solder resistance. Is preferably used.

Claims (3)

(A) epoxy resin, (B) phenol resin, (C) curing accelerator, (D) fused silica having an average particle size of 5 to 40 μm, and (E) average particle size of 0.1 to 3 μm An epoxy resin composition for semiconductor encapsulation, comprising fused silica having a silanol group density of greater than 2.1 / nm ^{2 and} less than 4.0 / nm ² and (F) a coupling agent. The blending ratio of the fused silica (D) and the fused silica (E) is (D) / (E) = 97/3 to 75/25, and the blending ratio of (D) and (E) is , Ri 85 to 94 wt% der of the total semiconductor encapsulating epoxy resin composition, the blending ratio of (F), of ^{(18.066 / 1371291.948) × 10 5} ≦ ( coupling agent (F) Number of molecules) / (surface silanol groups of fused silica (D) and fused silica (E)) Number) ≦ (18.066 / 951788.448) × 10 5 satisfies the semiconductor encapsulating epoxy resin composition. ^2. The semiconductor according to claim 1, wherein the surface of the fused silica (D) having an average particle diameter of 5 to 40 μm has a silanol group density of more than 1.0 / nm ^{2 and not} more than 4.0 / nm ^2. An epoxy resin composition for sealing. A semiconductor device obtained by sealing a semiconductor element using the epoxy resin composition for semiconductor sealing according to claim 1.