JP2000281751A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition which has good moldability and can give a cured product excellent in soldering resistance even in soldering after moisture absorption, which composition essentially consists of an epoxy resin, a phenolic resin, a silane coupling agent, a fused silica powder, and a cure accelerator and further contains at least either a specified epoxy resin or a specified phenolic resin, wherein the silane coupling agent is previously added to the epoxy resin or the phenolic resin. SOLUTION: Either an epoxy resin of formula I or a phenolic resin of formula I is used. In the formulae, R is H, a halogen or a 1-9C alkyl; an (n) is 1-5 on the average. The phenolic resin used is desirably one having a hydroxyl equivalent of 130-210. The silane coupling agent used is desirably an amino- containing silane. The silane coupling agent is added to the resin in a molten state under thorough agitation. The heating temperature is usually suitably 100-150 deg.C. The fused silica powder is used in an amount of, usually, 75-93 wt.% based on the entire composition and is desirably a spherical one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent moldability and solder resistance, and a semiconductor device using the same.

[0002]

2. Description of the Related Art Transfer molding of an epoxy resin composition is suitable as a method for encapsulating semiconductor elements such as ICs and LSIs at a low cost and suitable for mass production. The phenol resin has been improved to improve the characteristics. However, in the recent market trend of miniaturization, weight reduction and high performance of electronic devices, the integration of semiconductors has been increasing year by year, and the surface mounting of semiconductor devices has been promoted. Demands for resin compositions are becoming more stringent. For this reason, a problem which cannot be solved by the conventional epoxy resin composition has come out. The biggest problem is that
Due to the adoption of surface mounting, the semiconductor device is rapidly exposed to a high temperature of 200 ° C. or more in a solder immersion or reflow process, and cracks are generated in the semiconductor device due to stress when moisture absorbed explosively evaporates. This is a phenomenon in which peeling occurs at the interface between each of the various bonded portions on the element, the lead frame, and the inner lead and the cured product of the resin composition, and the reliability is significantly reduced.

[0003] In order to improve the reliability reduction due to soldering, the amount of fused silica powder in the epoxy resin composition is increased to achieve low moisture absorption, high strength, and low thermal expansion, thereby improving solder resistance. A method of improving the flowability and maintaining low viscosity and high fluidity during molding by using a resin having a low melt viscosity is becoming common. On the other hand, the adhesiveness at the interface between a cured product of an epoxy resin composition and a substrate such as a semiconductor element or a lead frame existing inside a semiconductor device has become very important in reliability by soldering. If the adhesive force at the interface is weak, peeling occurs at the interface with the base material after the soldering, and further, cracks occur in the semiconductor device due to the peeling. Many proposals have been made for epoxy resins and phenolic resins from the viewpoint of improving the adhesive strength at the interface. In particular, epoxy resins of general formula (1) and general formulas (2)
The phenolic resin is characterized by its flexibility and low hygroscopicity, and is known to be suitable (Japanese Patent Laid-Open No. Hei 5-
343570, JP-A-6-80763, JP-A-8-14
3648 publications).

A resin composition using an epoxy resin represented by the general formula (1) or a phenol resin represented by the general formula (2) as a curing agent has characteristics of flexibility and low moisture absorption. Has a remarkable effect of preventing peeling from the base material due to the low stress generated. However, on the other hand, as is clear from the structures of the general formulas (1) and (2),
Low density of polar groups in the cross-linking structure of the reactant, interface with each substrate such as inorganic coating film such as silicon nitride, organic coating film such as polyimide, lead frame made of copper or iron-nickel alloy, etc. It is disadvantageous from the viewpoint of adhesive strength. For this reason, an epoxy resin composition capable of preventing peeling from the substrate during the moisture absorption soldering process by further improving the adhesive strength with the substrate within a range that does not impair the characteristics of flexibility and low moisture absorption is desired. ing.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a resin having excellent moldability and excellent in soldering resistance which does not cause cracks or peeling off from a base material in a cured semiconductor device even in soldering after moisture absorption. It has been made for the purpose of providing a composition.

[0006]

The present invention comprises (A) an epoxy resin, (B) a phenolic resin, (C) a silane coupling agent, (D) a fused silica powder, and (E) a curing accelerator as essential components. In the epoxy resin composition containing at least one selected from the epoxy resin represented by the general formula (1) and the phenol resin represented by the general formula (2), the silane coupling agent may be selected from the group consisting of (A) epoxy A resin or an epoxy resin composition for semiconductor encapsulation, which is previously mixed with (B) a phenol resin by heating.
And a semiconductor device in which a semiconductor element is sealed using the same.

Embedded image (R in the formula is a hydrogen atom, a halogen atom, or a carbon atom 1
A group selected from the alkyl groups from 1 to 9, which may be the same or different, and n is an average value and a positive number of 1 to 5)

[0007]

Embedded image (R in the formula is a hydrogen atom, a halogen atom, or a carbon atom 1
A group selected from the alkyl groups from 1 to 9, which may be the same or different, and n is an average value and a positive number of 1 to 5)

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The epoxy resin represented by the general formula (1) used in the present invention refers to all monomers, oligomers and polymers having an epoxy group, for example, a biphenyl type epoxy resin,
Crystalline epoxy resin such as stilbene type epoxy resin, hydroquinone type epoxy resin, bisphenol F type epoxy resin, bisphenol A type epoxy resin, orthocresol novolak type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, triphenol methane type epoxy resin And a naphthol type epoxy resin, and an epoxy resin represented by the general formula (1). These epoxy resins may be used alone or in combination. Among them, a preferred epoxy resin is an epoxy resin represented by the general formula (1).
The epoxy resin represented by the general formula (1) is an epoxy resin having two or more epoxy groups in one molecule, and is characterized by having a hydrophobic structure between epoxy groups. The cured product of the phenolic resin has a low cross-linking density and a large hydrophobic structure, and thus has a low moisture absorption rate. Therefore, the thermal stress during molding of the epoxy resin composition or the solder after moisture absorption of a semiconductor device as a molded product. Reduces thermal stress generated during processing and has excellent adhesion to substrate. On the other hand, since the hydrophobic structure between the epoxy groups is a rigid biphenyl skeleton, it has a feature that the heat resistance is not significantly reduced despite the low crosslinking density.
Specific examples of the epoxy resin represented by the general formula (1) are shown below, but are not limited thereto.

Embedded image Particularly, in order to increase the filling amount of the fused silica powder of the epoxy resin composition, the above-mentioned crystalline epoxy resin which exhibits crystallinity at room temperature and extremely lowers the melt viscosity at the molding temperature is preferable.

The phenolic resin used in the present invention refers to all monomers, oligomers and polymers having a phenolic hydroxyl group, such as phenol novolak resin,
Examples thereof include, but are not limited to, cresol novolak resin, terpene-modified phenol resin, dicyclopentadiene-modified phenol resin, bisphenol A, triphenolmethane, and the phenol resin represented by the general formula (2). In order to improve the low moisture absorption of the cured product of the resin composition and the adhesion to the substrate, the hydroxyl equivalent is preferably 130.
To 210 are preferred. These phenol resins may be used alone or in combination. Among these phenol resins, a phenol resin represented by the general formula (2) is preferable. General formula (2)
Is exactly the same as described for the epoxy resin represented by the general formula (1), except that the epoxy resin represented by the general formula (1) is combined with the phenol resin represented by the general formula (2). In such a case, the semiconductor device has low moisture absorption,
The greatest effect is obtained in reliability such as solder crack resistance and adhesion in the solder treatment after moisture absorption. Specific examples of the phenol resin represented by the general formula (2) are shown below, but are not limited thereto.

Embedded image

Examples of the fused silica powder used in the present invention include natural silica melted in a flame, and synthetic silica obtained by hydrolyzing tetramethoxysilane, tetraethoxysilane and the like. Further, there are spherical silica and crushed silica depending on the shape and production method. The blending amount of the fused silica powder is 75 to 9 in the total resin composition.
3% by weight is preferred. If the content is less than 75% by weight, the amount of moisture absorbed by the cured product of the resin composition increases, and the strength at the soldering temperature is reduced. On the other hand, if it exceeds 93% by weight, the fluidity during molding of the resin composition decreases,
Unfilling, chip shift, and pad shift are likely to occur, which is not preferable. Particularly, in order to highly fill the fused silica powder, a spherical one is preferable. Further, a broad particle size distribution is effective for reducing the melt viscosity of the resin composition during molding.

The silane coupling agent used in the present invention is characterized in that the silane coupling agent is heated and mixed in an epoxy resin or a phenol resin in advance. In the formulation of the silane coupling agent, the surface of the fused silica is pre-treated with the silane coupling agent to improve the affinity of the interface between the fused silica and the resin component, or to form a chemical bond, thereby forming a resin composition. It is generally used for the purpose of improving the mechanical properties of a cured product of the above. This utilizes the feature that the silane coupling agent easily hydrolyzes to form a hydrogen bond or a covalent bond between water adsorbed on the fused silica and silanol groups present on the fused silica surface. Things. On the other hand, other than fused silica, silane coupling agents improve the affinity of the interface between the cured product of the resin composition and various base materials present inside the semiconductor device, and the adhesiveness of the interface due to the formation of chemical bonds. It is also effective in improving the quality. In this case, the compounded silane coupling agent is not adsorbed or bonded to the surface of the fused silica in the mixing step of the epoxy resin composition, and easily migrates to the interface with various substrates at the time of molding the epoxy resin composition. It becomes necessary. For this purpose, a mixing step is required in which the silane coupling agent does not come into direct contact with the fused silica, and a suitable method is to heat and mix the silane coupling agent with the resin in advance.

The silane coupling agent used in the present invention includes γ-aminopropyltriethoxysilane, N
Silane having an amino group such as -β (aminoethyl) γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane Silane having an epoxy group such as β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, silane having a mercapto group such as γ-mercaptopropyltrimethoxysilane, silane having a vinyl group such as vinyltrimethoxysilane, γ Examples thereof include silane having a methacryl group such as-(methacryloxypropyl) trimethoxysilane, but are not limited thereto. Among the above silane coupling agents, the silane coupling agent having an amino group has an advantage of excellent adhesiveness to various substrates, but on the other hand, easily reacts upon contact with fused silica and is fixed to the silica surface. In particular, it is particularly effective to heat and mix the resin with the resin in order to have the characteristic of being removed. In the epoxy resin composition of the present invention, it is essential that the silane coupling agent is previously mixed with the epoxy resin or the phenol resin by heating, but in addition, the silane coupling agent is treated on the surface of ordinary fused silica. It may contain a silane coupling agent or a silane coupling agent added when each component is mixed in the step of producing the epoxy resin composition. In the heating and mixing, it is usually necessary to heat the resin to a temperature higher than the softening point of the resin, add the silane coupling agent to the molten resin, and mix well. If the heating temperature is high, the silane coupling agent volatilizes before being mixed with the resin, so the heating temperature is preferably performed at a low temperature within a range where the resin can be efficiently mixed, and is usually 100 ° C to 150 ° C.
Is appropriate.

The curing accelerator used in the present invention refers to a curing accelerator which can act as a catalyst for the crosslinking reaction between the epoxy resin and the phenol resin. Specific examples include tributylamine,
1,8-diazabicyclo (5,4,0) undecene-7
And the like, an organic phosphorus-based compound such as triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salt, and an imidazole compound such as 2-methylimidazole. These may be used alone or as a mixture.

The resin composition of the present invention comprises, in addition to the components (A) to (E), a brominated epoxy resin, a flame retardant such as antimony trioxide, a low stress agent represented by a polysiloxane compound, if necessary, A colorant represented by carbon black, a release agent such as carnauba wax, a long-chain fatty acid, or polyethylene oxide can be appropriately compounded. The resin composition of the present invention comprises: (A) a melt mixture of the epoxy resin of the general formula (1) or the phenol resin of the general formula (2) and (D) a silane coupling agent in advance; Silica powder,
(E) It is obtained by mixing a curing accelerator and other additives using a mixer or the like, heating and kneading the mixture using a heating kneader or a hot roll, and then cooling and pulverizing. In order to manufacture an electronic device such as a semiconductor device by encapsulating an electronic component using the resin composition of the present invention, it is only necessary to cure and mold by a conventional molding method such as transfer molding, compression molding and injection molding.

Hereinafter, the present invention will be described specifically with reference to Examples. The mixing unit is parts by weight. Production Example of Melt Mixture Melt-mixed phenolic resin A: phenol aralkyl resin (manufactured by Mitsui Chemicals, Inc., XL225-LL, softening point 75)
C., hydroxyl equivalent 175; hereinafter, 4.6 parts by weight of phenol aralkyl resin) and 0.3 parts by weight of γ-aminopropyltriethoxysilane were stirred and mixed at 120 ° C. for 30 minutes to obtain a molten mixed phenolic resin A. . 6. Melt-mixed epoxy resin B: epoxy resin of formula (3)
4 parts by weight and 0.3 part by weight of γ-glycidoxypropyltrimethoxysilane were stirred and mixed at 120 ° C. for 30 minutes,
A melt-mixed epoxy resin B was obtained.

Embedded image

4. Melt-mixed phenolic resin C: phenolic resin of formula (4) (hydroxyl equivalent 195, softening point 70 ° C.)
0 parts by weight and 0.3 parts by weight of N-phenyl-γ-aminopropyltrimethoxysilane were stirred and mixed at 120 ° C. for 30 minutes to obtain a melt-mixed phenolic resin C.

Embedded image

Melt-mixed phenolic resin D: 5.7 parts by weight of the phenol aralkyl resin used in Example 1 and 0.3 part by weight of γ-aminopropyltriethoxysilane
The mixture was heated at ℃ and stirred and mixed for 30 minutes to obtain a melt-mixed phenolic resin D.

Example 1 Melt-mixed phenolic resin A 4.9 parts by weight Epoxy resin of formula (3) (epoxy equivalent 270, softening point 60 ° C.) 7.4 parts by weight Spherical fused silica powder 87.0 parts by weight 1,8 0.2 parts by weight of diazabicyclo (5,4,0) undecene-7 (hereinafter abbreviated as DBU) 0.2 parts by weight of carnauba wax 0.3 parts by weight of carbon black were mixed using a mixer, and the surface temperature was 90%. ° C and 4
The mixture was kneaded 30 times using two rolls at 5 ° C., and the obtained kneaded material sheet was cooled and pulverized to obtain a resin composition. The obtained resin composition was evaluated by the following method. Table 1 shows the results.

Evaluation method Spiral flow: Using a mold for measuring spiral flow according to EMMI-I-66, using a mold temperature of 175 ° C.
The measurement was performed at an injection pressure of 70 kg / cm ² and a curing time of 2 minutes.
The unit is cm. Heat strength: Flexural strength at 240 ° C. is determined according to JIS-K6911.
It measured according to. The unit is kgf / mm ² . Solder resistance: 100-pin TQFP (package size is 1
4 × 14 mm, thickness 1.4 mm, silicon chip size 8.0 × 8.0 mm, lead frame made of 42 alloy), mold temperature 175 ° C., injection pressure 75 kg / c
transfer molding with m ² , curing time 2 minutes, 175
Post-curing was performed at 8 ° C. for 8 hours. The obtained semiconductor package was placed in an environment of 85 ° C. and 85% relative humidity for 72 hours and 16 hours.
It was left for 8 hours and then immersed in a 240 ° C. solder bath for 10 seconds. Observe the external cracks with a microscope and determine the number of cracks ((number of cracked packages) / (total number of packages)
× 100) was expressed in%. Also, the ratio of the peeled area between the chip and the resin composition was measured using an ultrasonic flaw detector, and the average value of five packages was determined as the peeling rate ((peeled area) / (chip area) × 100). ,%.

Examples 2 to 4 and Comparative Examples 1 to 3 Each component was blended in the proportions shown in Table 1 to obtain a resin composition in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 1 shows the results. In addition, the treated silica used other than Example 1 is shown below. Treated silica: spherical fused silica used in Example 1 87.0
While stirring parts by weight, 0.3 parts by weight of γ-aminopropyltriethoxysilane was sprayed. The treated silica was left at room temperature for 24 hours.

[0021]

[Table 1]

[0022]

When the resin composition of the present invention is used, a semiconductor device which is excellent in moldability and sealed is excellent in strength when heated and low in hygroscopicity, so that it has excellent solder resistance after moisture absorption.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/29 H01L 23/30 R 23/31 F term (Reference) 4J002 CC07X CD06W DJ017 EN028 EU118 EU138 EW018 EW178 EX006 EX076 FB09W FB09X FB14W FB14X FD158 GQ05 4J036 AA01 AA04 AF07 DC05 DC41 DC46 DD07 FA05 FA13 FB08 GA04 GA23 JA07 4M109 AA01 BA01 CA21 EA02 EB03 EB04 EB06 EB09 EB13 EC01 EC03 EC20

Claims (3)

[Claims] (1) An epoxy resin, (B) a phenol resin, (C) a silane coupling agent, (D) a fused silica powder, and (E) a curing accelerator as essential components. In the epoxy resin composition containing at least one selected from the epoxy resin represented by formula (1) or the phenolic resin represented by formula (2), the silane coupling agent is (A) epoxy resin or (B) phenolic resin. An epoxy resin composition for encapsulating a semiconductor, which is previously mixed by heating. Embedded image (R in the formula is a hydrogen atom, a halogen atom, or a carbon atom 1
Which may be the same or different, and n is an average value and is a positive number of 1 to 5) (R in the formula is a hydrogen atom, a halogen atom, or a carbon atom 1
A group selected from the alkyl groups from 1 to 9, which may be the same or different, and n is an average value and a positive number of 1 to 5) 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the silane coupling agent has an amino group. 3. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim 1.