JPH0925327A - Epoxy resin composition and semiconductor device sealed therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition excellent in humidity resistance, moldability and soldering-heat resistance by mixing a specified epoxy resin with a specified dicyclopentadiene/phenol polymer, a methyl methacrylate/ butadiene/styrene copolymer resin and a specified silicon nitride powder. SOLUTION: This epoxy resin composition consists essentially of an epoxy resin represented by formula I, a dicyclopentadiene/phenol polymer represented by formula II (wherein R<2> is Cm H2m+1 ; and (m) and (n) are each 0 or an integer of 1 or greater), a methyl methacrylate/butadiene/styrene copolymer resin and 25-90wt.%, based on the total resin composition, silicon nitride powder having an concentration of surface oxygen present in the SiO2 layer of 0.5-15% and a mean particle diameter of 10-50μm.

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. Since this sealing resin is economically advantageous as compared with the hermetic sealing method using glass, metal, and ceramic, it is widely used. As a sealing resin, an epoxy resin is most commonly used among thermosetting resins 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. It is widely used as a resin for semiconductor encapsulation because it is superior in moldability and reliability, has no toxicity, and is inexpensive as compared with the resin. 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 to the high heat conductivity of the sealing resin composition using the crystalline 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 a good balance of these characteristics.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that by using a specific epoxy resin, a specific phenolic polymer 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 (B) Dicyclopentadiene / phenolic polymer represented by the following general formula

[0008]

[Chemical 6] (In the formula, R ² represents C _m H _{2m + 1} , m and n represent 0 or an integer of 1 or more, respectively.) (C) Methyl methacrylate / butadiene / styrene copolymer resin and (D) SiO ₂ Surface oxygen concentration by layer is 0.5-15%,
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. It is a composition. A semiconductor sealing device is characterized in that a semiconductor chip is sealed with a cured product of the epoxy resin composition.

Hereinafter, the present invention will be described in detail.

As the epoxy resin (A) used in the present invention, the one represented by the above chemical formula 5 is used.

The (B) dicyclopentadiene / phenol polymer 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. It As a specific polymer, for example,

[0012]

Embedded image

[0013]

Embedded image And the like, and these can be used alone or as a mixture.

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.

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 mix them so as to contain 1 to 10% by weight.
More preferably, it is in the range of 1.0 to 5.0% by weight. If the proportion is less than 0.1% by weight, there is no effect on the elastic modulus, 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, it is not preferable because the wire gate may be clogged, the wire may flow, and the mold may be worn during molding. On the other hand, if the diameter is too small, the specific surface area increases and the filling properties deteriorate, 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 heat dissipation are undesirably reduced. As the silicon nitride to be hydrolyzed, trigonal (α-Si ₃ N ₄ ) or hexagonal (β
—Si ₃ N ₄ ) and the like, and these can be used alone or in combination of two or more. The compounding ratio of the silicon nitride powder is 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 phenol resin, a methylmethacrylate / butadiene / styrene copolymer resin and a specific silicon nitride powder as essential components, but does not meet the purpose of the present invention. Release agent such as natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides, esters, paraffins, chlorinated paraffins, bromotoluene, hexabromo Flame retardants such as benzene and antimony trioxide, colorants 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 sealing method 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. The curing by heating is desirably performed by heating to 150 ° C. or more.

[0020]

The present invention uses a specific epoxy resin, a specific phenolic resin, a methylmethacrylate / butadiene / styrene copolymer resin, and a specific silicon nitride powder in an epoxy resin composition to obtain moisture resistance and moldability. , Excellent in mold abrasion resistance, small in coefficient of thermal expansion, good in thermal conductivity and heat dissipation, and can be a highly reliable resin composition having well-balanced characteristics thereof, and using this resin composition As a result, a highly reliable semiconductor device can be manufactured.

[0021]

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 13% of the epoxy resin shown in the above Chemical formula 5, 11% of the phenolic resin shown in the above Chemical formula 7, hexagonal silicon nitride powder (average after removing coarse particles on a 150 mesh sieve) Particle size 17 μm
, Surface oxygen concentration 7%) 71%, methyl methacrylate
Butadiene / styrene copolymer resin 2% and release agent 3
% At room temperature, kneading and cooling at 90-95 ° C,
Pulverization produced a molding material.

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: 50mm in diameter and 3mm in thickness by transfer molding
The molded article was left in a saturated steam at 127 ° C. and 2.5 atm for 24 hours, and measured by the increased weight. * 2: Make a molded product similar to that of the case of water absorption, 175 ℃, 8
After post-curing for a certain time, a test piece of an appropriate size was prepared and 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 mold, 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 and transfer mold at 175 ° C for 2 minutes.
Post-curing was performed at 175 ° C for 8 hours. The molded article thus obtained was previously subjected to a moisture absorption treatment at 40 ° C. and 95% RH for 100 hours.
It was immersed in a 250 ° C. solder bath for 10 seconds. After that, 127 ℃
PCT was performed in 2.5 atm of saturated steam, and 50% disconnection due to aluminum corrosion was evaluated as defective. * 7: 8 × 8mm dummy chip with Q-FP (14 × 14 × 1.4
mm) package, transfer molding was performed using the molding material at 175 ° C for 2 minutes, and then post-curing was performed at 175 ° C for 8 hours. The semiconductor encapsulation device obtained in this way is 85 ℃, 85%,
After the moisture absorption treatment for 24 hours, it was immersed in a 240 ° C. solder bath for 1 minute. After that, observe the package surface with a stereo microscope,
The occurrence of external resin cracks was evaluated. * 8: The molding material is preheated, and transfer molding is performed at 175 ° C using a die 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. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 23/31

Claims (2)

[Claims] (A) an epoxy resin represented by the following general formula: (B) Dicyclopentadiene / phenolic polymer represented by the following general formula: (In the formula, R ² represents C _m H _{2m + 1} , m and n represent 0 or an integer of 1 or more, respectively.) (C) Methyl methacrylate / butadiene / styrene copolymer resin and (D) SiO ₂ Surface oxygen concentration by layer is 0.5-15%,
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 (B) Dicyclopentadiene / phenolic polymer represented by the following general formula: (In the formula, R ² represents C _m H _{2m + 1} , m and n represent 0 or an integer of 1 or more, respectively.) (C) Methyl methacrylate / butadiene / styrene copolymer resin and (D) SiO ₂ Surface oxygen concentration by layer is 0.5-15%,
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. A semiconductor encapsulation device, wherein a semiconductor chip is encapsulated with a cured product of the composition.