JPH08311161A - Epoxy resin composition and sealed semiconductor device - Google Patents

Abstract

PURPOSE: To obtain an epoxy resin composition, excellent in moisture and solder heat resistances and moldability, well balanced in characteristics and useful as a sealed semiconductor device having high reliability by using a specific epoxy resin, a specified phenolic resin and a specific silicon nitride powder. CONSTITUTION: This epoxy resin composition consists essentially of (A) an epoxy resin of formula I [R<1> is a group of (Cl H2l+1 ) ; (l) is 0 or an integer of >=1; (n) is an integer of >=1], (B) a naphthol resin of formula II, (C) a methyl methacrylate-butadiene-styrene copolymer resin and (D) a silicon nitride powder having 0.5-15% surface oxygen concentration due to an SiO2 layer and 10-50μm average particle diameter and contains 25-90wt.% component (D) based on the resin composition. The blending ratio of the component (C) is preferably 0.1-10wt.%, more preferably 1.0-5.0wt.% based on the whole resin composition. The sealed semiconductor device is readily obtained by sealing a semiconductor chip with a molding material prepared from the resin composition.

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 and a semiconductor encapsulation device which are excellent in moisture resistance, moldability and solder heat resistance and have a good balance of properties.

[0002]

2. Description of the Related Art Conventionally, a method of sealing electronic parts such as diodes, transistors and integrated circuits with a thermosetting resin has been used. This sealing resin is economically advantageous as compared with the hermetic sealing method using glass, metal, or ceramic, and is therefore widely put into practical use. Among thermosetting resins, epoxy resins are most commonly used as the encapsulating resin in terms of reliability and price. Hardeners such as acid anhydrides, aromatic amines, and novolac-type phenolic resins are used as epoxy resins. Among these, epoxy resins using novolac-type phenolic resins as hardeners use other hardeners. Compared to other products, it has excellent moldability and reliability, is non-toxic, and is inexpensive,
Widely used as a resin for semiconductor encapsulation. As the filler, fused silica powder or crystalline silica powder is generally used together with the above-mentioned curing agent. In recent years, with the increase in power consumption of surface mounting of semiconductor components, there has been a demand for development of a semiconductor encapsulating resin having good heat dissipation, solder heat resistance, and low stress.

However, a resin composition comprising an epoxy resin having a novolac type phenolic resin as a curing agent and a fused silica powder has a small coefficient of thermal expansion and good moisture resistance, and has a bonding wire open-circuited by a hot and cold cycle test. Although it has a feature of being excellent in cracks, pellet cracks, etc., it has a drawback that it cannot perform its function in a power semiconductor having large heat consumption because of its poor heat dissipation due to its low thermal conductivity. On the other hand, in a resin composition comprising an epoxy resin using a novolac type phenol resin as a curing agent and crystalline silica powder, increasing the compounding ratio of the crystalline silica powder increases the thermal conductivity and also improves heat dissipation. However, the coefficient of thermal expansion is large,
There is a drawback in that the reliability with respect to moisture resistance also deteriorates. Further, the sealed product obtained from this resin composition has the drawbacks that the mechanical properties are deteriorated and that the die is largely worn during molding. Therefore, there is a limit in achieving high thermal conductivity of the encapsulating resin composition using silica powder.

[0004]

The present invention has been made to solve the above-mentioned drawbacks, and is excellent in moisture resistance, solder heat resistance, moldability, especially filling property of thin portion, and die abrasion resistance. , Small coefficient of thermal expansion, good thermal conductivity and heat dissipation,
It is an object of the present invention to provide a highly reliable epoxy resin and a semiconductor encapsulation device having well-balanced characteristics thereof.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that by using a specific epoxy resin, a specific phenolic resin and a specific silicon nitride powder, The inventors have found that the above objects can be achieved and completed the present invention.

That is, the present invention provides (A) an epoxy resin represented by the following general formula:

[0007]

Embedded image (However, in the formula, R ¹ represents ( _Cl H _{2l + 1} ), l represents 0 or an integer of 1 or more, and n represents an integer of 1 or more.) (B) Naphthol represented by the following general formula resin

[0008]

[Chemical 6] (Wherein Rn represents 0 or an integer of 1 or more) (C) methyl methacrylate / butadiene / styrene copolymer resin and (D) the surface oxygen concentration by the SiO ₂ layer is 0.5 to 15%,
An epoxy resin characterized by containing silicon nitride powder having an average particle size of 10 to 50 μm as an essential component and containing the silicon nitride powder of (D) in a proportion of 25 to 90% by weight with respect to the resin composition. It is a composition. A semiconductor encapsulation device is obtained by encapsulating a semiconductor chip with a cured product of this epoxy resin composition.

The present invention will be described in detail below.

As the epoxy resin (A) used in the present invention, the one represented by the above general formula 5 is used, but the molecular weight and the like are not particularly limited. As a concrete example, for example,

[0011]

[Chemical 7] Is mentioned. In addition, a novolac-based epoxy resin or an epibis-based epoxy resin can be used in combination with these epoxy resins.

The naphthol resin (B) used in the present invention has a skeleton structure represented by the above general formula 6 and is widely included without being particularly limited in molecular structure, molecular weight and the like. Further, a novolac type phenol resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and modified resins thereof can be used in combination. As a specific naphthol resin, for example,

[0013]

Embedded image

[0014]

[Chemical 9] Etc.

The (C) methylmethacrylate / butadiene / styrene copolymer resin used in the present invention is a copolymer of methylmethacrylate, butadiene and styrene, and is not limited to the composition ratio of each monomer. The mixing ratio of this methyl methacrylate / butadiene / styrene copolymer resin is 0.
It is preferable to add 1 to 10% by weight.
More preferably, it is within the range of 1.0 to 5.0% by weight. If the proportion is less than 0.1% by weight, the elastic modulus is not effective, and if it exceeds 10% by weight, the moldability is poor and it is not suitable for practical use.

The silicon nitride powder (D) used in the present invention is obtained by removing coarse particles on a 150-mesh sieve and has an average particle diameter of 10 to 50 μm. Average particle size is 10μ
When it is less than m or more than 50 μm, there is a problem in fluidity and workability, which is not preferable. In particular, if the particle size is coarse on a 150-mesh screen, wire gate clogging, wire flow, die wear, etc. may occur during molding, which is not preferable. On the other hand, if the diameter is too small, the specific surface area increases and the filling property deteriorates, which is not preferable. The surface of the silicon nitride forms a Si O ₂ layer by hydrolysis, the oxygen concentration of the surface due to the Si O ₂ layer is desirably in the range from 0.5 to 15%. If the oxygen concentration is less than 0.5%, the die wear resistance is not effective and the moisture resistance is poor. On the other hand, if it exceeds 15%, the thermal conductivity and the heat dissipation property are deteriorated, which is not preferable. Hydrolyzed silicon nitride includes trigonal (α-Si ₃ N ₄ ) or hexagonal (β
—Si ₃ N ₄ ) and the like, which may be used alone or in combination of two or more. The compounding ratio of the silicon nitride powder is preferably 25 to 90% by weight based on the total resin composition. If the proportion is less than 25% by weight, the coefficient of thermal expansion increases and the thermal conductivity decreases, which is not preferable. Further, if it exceeds 90% by weight, the dryness becomes large and the moldability is poor and it is not suitable for practical use.

The epoxy resin composition of the present invention contains a specific epoxy resin, a specific phenolic resin, a methyl methacrylate / butadiene / styrene copolymer resin and a specific silicon nitride powder as essential components, but for the purpose of the present invention. As long as it does not conflict, and if necessary, for example, natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides, esters, release agents such as paraffins, chlorinated paraffins, bromotoluene, and hexa Brombenzene,
A flame retardant such as antimony trioxide, a coloring agent such as carbon black and red iron oxide, various curing agents and the like can be appropriately added and blended.

The general method for preparing the epoxy resin composition of the present invention as a molding material is as follows: the specific epoxy resin, the specific phenolic resin, the methylmethacrylate / butadiene / styrene copolymer resin, the specific silicon nitride. Powder and other raw materials selected to have a predetermined composition ratio are sufficiently mixed with a mixer or the like, and then melt-mixed with a heat roll, and then cooled and solidified and ground into a suitable size to obtain a molding material. be able to. When the molding material thus obtained is applied to sealing, coating, insulation, etc. of electronic parts or electric parts such as semiconductor devices, excellent properties and reliability can be imparted.

The semiconductor encapsulation device of the present invention can be easily manufactured by encapsulating a semiconductor chip using the above-mentioned molding material. The semiconductor chip to be sealed is not particularly limited to, for example, an integrated circuit, a large scale integrated circuit, a transistor, a thyristor, a diode and the like. The most common method of sealing is a low-pressure transfer molding method, but sealing by injection molding, compression molding, casting or the like is also possible. The epoxy resin composition is heated and cured at the time of encapsulation, and finally a semiconductor encapsulating device encapsulated by the cured product of the composition is obtained. For curing by heating, it is desirable to heat and cure at 150 ° C or higher.

[0020]

The present invention uses an epoxy resin composition containing a specific epoxy resin, a specific phenolic resin, a methylmethacrylate / butadiene / styrene copolymer resin and a specific silicon nitride powder to obtain moisture resistance and solder heat resistance. Of resin, moldability, and die abrasion resistance, small coefficient of thermal expansion, good thermal conductivity, and good heat dissipation, and a highly reliable resin composition with well-balanced characteristics thereof. By using the composition, a highly reliable semiconductor device can be manufactured.

[0021]

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, “%” means “% by weight”.

Example 1 11% of the epoxy resin shown in Chemical formula 7 above, 13% of the phenolic resin shown in Chemical formula 8 above, hexagonal silicon nitride powder (average particle size after removing coarse particles on a 150 mesh screen) 17 μm, surface oxygen concentration 7%) 71%, methylmethacrylate / butadiene / styrene copolymer resin 2% and mold release agent 3% are mixed at room temperature, kneaded and cooled at 90 to 95 ° C, then crushed and molded. The material was manufactured.

Example 2 Trigonal system silicon nitride powder was used in place of the hexagonal system silicon nitride powder used in Example 1 (average particle size of 17 μm after removal of coarse particles on 150 mesh sieve, surface oxygen concentration 7%). A molding material was produced in the same manner as in Example 1 except that a mixed powder of 31% and 40% of crystalline silica powder (average particle diameter 38 μm) was used.

Comparative Example 1 Cresol novolac epoxy resin (epoxy equivalent 215
) 18%, novolac type phenolic resin (phenol equivalent 107) 8%, hexagonal silicon nitride powder (average particle size 17 μm after removing coarse particles on 150 mesh sieve) 71% and release agent 3% at room temperature Then, a molding material was produced in the same manner as in Example 1.

Comparative Example 2 Instead of the hexagonal silicon nitride powder in Comparative Example 1,
A molding material was manufactured in the same manner as in Comparative Example 1 except that hexagonal silicon nitride powder (average particle size of 60 μm passing through 60 mesh) was used.

Semiconductor chips were encapsulated using the molding materials produced in Examples 1-2 and Comparative Examples 1-2, and cured by heating at 170 ° C. to produce semiconductor encapsulation devices. Various tests were performed on the molding material and the semiconductor encapsulation device, and the results are shown in Table 1. The epoxy resin composition and the semiconductor encapsulation device of the present invention have good thermal characteristics, moisture resistance, and solder heat resistance. It was excellent in moldability and moldability, and the remarkable effect of the present invention could be confirmed.

[0027]

[Table 1] * 1: A molded product with a diameter of 50 mm and a thickness of 3 mm was made by transfer molding, left to stand in saturated steam at 127 ° C and 2.5 atm for 24 hours, and measured by the increased weight. * 2: A molded product similar to the case of water absorption was prepared, post-cured at 175 ° C for 8 hours, and a test piece of appropriate size was measured using a thermomechanical analyzer. * 3: Tested according to JIS-K-6911. * 4: The semiconductor sealing device was measured at room temperature using a rapid thermal conductivity meter (Showa Denko KK, trade name QTM-MD). * 5: Using a 120-cavity 16-pin P die, the molding material was transfer-molded at 170 ° C for 3 minutes, and the filling property was evaluated. ○ mark: good, × mark: bad * 6: Using a molding material, attach a silicon chip with two or more aluminum wires to a normal 42 alloy frame, transfer mold at 175 ° C for 2 minutes, and then at 175 ° C for 8 hours. Cured. The molded product thus obtained was previously subjected to moisture absorption treatment at 40 ° C., 95% RH for 100 hours, and then immersed in a solder bath at 250 ° C. for 10 seconds. After that, PCT was performed in saturated steam at 127 ° C. and 2.5 atm, and 50% disconnection due to corrosion of aluminum was evaluated as defective. * 7: An 8x8mm dummy chip was placed in a Q-FP (14x14x1.4mm) package, transfer molding was performed for 2 minutes at 175 ° C using the molding material, and post-curing was performed at 175 ° C for 8 hours. . The semiconductor encapsulation device thus obtained was subjected to moisture absorption treatment at 85 ° C, 85% for 24 hours, and then immersed in a solder bath at 240 ° C for 1 minute. After that, the surface of the package was observed with a stereoscopic microscope to evaluate the presence or absence of external resin cracks. * 8: The molding material is preheated, and transfer molding is performed at 175 ° C using a mold with a 0.5 mm diameter hard chrome plating material flow hole. It was evaluated by the number of shots when the hole diameter was 5% worn.

[0028]

As is apparent from the above description and Table 1, the epoxy resin composition and the semiconductor encapsulating device of the present invention have the moisture resistance, the solder heat resistance, the moldability of the resin composition, especially the filling property of the thin portion. Excellent in mold abrasion resistance, small coefficient of thermal expansion, good thermal conductivity and heat dissipation, and well-balanced characteristics of them, and a highly reliable semiconductor encapsulation device can be manufactured. .

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Claims (2)

[Claims] 1. An epoxy resin represented by the following general formula (A): (However, in the formula, R ¹ represents ( _Cl H _{2l + 1} ), l represents 0 or an integer of 1 or more, and n represents an integer of 1 or more.) (B) Naphthol represented by the following general formula Resin [Chemical 2] (However, n represents 0 or an integer of 1 or more in the formula) (C) The surface oxygen concentration by the methyl methacrylate / butadiene / styrene copolymer resin and (D) SiO ₂ layer is 0.5 to 15%,
Epoxy resin characterized by containing silicon nitride powder having an average particle diameter of 10 to 50 μm as an essential component and containing the silicon nitride powder of (D) in a proportion of 25 to 90% by weight with respect to the resin composition. Composition. 2. An epoxy resin represented by the following general formula (A): embedded image (However, in the formula, R ¹ represents ( _Cl H _{2l + 1} ), l represents 0 or an integer of 1 or more, and n represents an integer of 1 or more.) (B) Naphthol represented by the following general formula Resin [Chemical 4] (However, n represents 0 or an integer of 1 or more in the formula) (C) The surface oxygen concentration by the methyl methacrylate / butadiene / styrene copolymer resin and (D) SiO ₂ layer is 0.5 to 15%,
A cured product of an epoxy resin composition containing silicon nitride powder having an average particle size of 10 to 50 μm as an essential component and containing 25 to 90% by weight of the silicon nitride powder of (D) with respect to the resin composition, A semiconductor encapsulation device characterized by encapsulating a semiconductor chip.