JPH07242729A - Epoxy resin composition and sealed semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition for semiconductor chip sealing by mixing as essential ingredients an epoxy-novolak resin, a phenolic resin, a specific amount of an inorganic filler, and a curing accelerator. CONSTITUTION:This composition comprises as essential components an epoxy resin represented by formula I (wherein R<1> is t-butyl; R<2> is methyl; R<3> is a group represented by CkH2k+1; R4 is a group represented by CmH2m+1; and k, m, and n each is an integer of 0 or larger), a phenolic resin, an inorganic filler, and a curing accelerator, the amount of the filler being 25-90wt.% based on the whole composition. Examples of the phenolic resin include phenolic novolaks obtained by reacting phenol or a phenol derivative, e.g. an alkylphenol, with either formaldehyde or paraformaldehyde and modifications of these phenolic novolaks. Examples of the filler include particulate silica having an average particle diameter of 30mum or smaller.

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 having excellent fluidity and solder heat resistance, and a semiconductor encapsulation device in which a semiconductor chip is encapsulated with the composition.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductor integrated circuits,
At the same time as technology development for high integration and high reliability, automation of the mounting process of semiconductor devices is being promoted. For example, when mounting a flat package type semiconductor device on a circuit board, conventionally, soldering is performed for each lead pin, but recently, a solder dipping method or a solder reflow method has been adopted.

[0003]

A conventional semiconductor device sealed with a resin composition comprising an epoxy resin containing 2% or more of a monomer such as a novolac type epoxy resin, a novolac type phenolic resin and silica powder has excellent fluidity. However, there is a drawback that the heat resistance is remarkably lowered, and the moisture resistance is lowered when the whole device is immersed in a solder bath. In particular, when a semiconductor device that has absorbed moisture is immersed, peeling between the encapsulating resin and the semiconductor chip, or the encapsulating resin and the lead frame, and internal resin cracks cause significant deterioration in moisture resistance, causing wire breakage and moisture due to electrode corrosion. As a result, there is a drawback that a semiconductor device cannot guarantee long-term reliability.

The present invention has been made in order to solve the above-mentioned drawbacks, has little influence of moisture absorption, is particularly excellent in moisture resistance, fluidity and solder heat resistance after immersion in a solder bath, and has a sealing resin and a semiconductor chip. Alternatively, an epoxy resin composition and a semiconductor encapsulation that can ensure long-term reliability without peeling between the encapsulation resin and the lead frame, internal resin cracks, wire breakage due to electrode corrosion, and leakage current due to moisture are not generated. It is intended to provide a stop device.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that a resin composition excellent in moisture resistance, solder heat resistance and the like can be obtained by using a specific epoxy resin. The present invention has been completed and the present invention has been completed.

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

[0007]

[Chemical 3] (However, in the formula, R ¹ is a t-butyl group, R ² is a methyl group,
R ³ represents a C ₁ H _{2l + 1} group, R ⁴ represents a C _m H _{2m + 1} group, and l, m and n in each group represent 0 or an integer of 1 or more.) (B) Phenolic resin ( C) Inorganic filler (D) Curing accelerator is an essential component, and the above (C) is used for the entire resin composition.
An epoxy resin composition, characterized in that it contains the inorganic filler of 25 to 95% by weight. 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 3 is used. Further, this epoxy resin can be used without being limited by its molecular weight or the like. As a specific compound, for example,

[0010]

[Chemical 4] (However, in the formula, n represents 0 or an integer of 1 or more)

[0011]

[Chemical 5] (However, in the formula, n represents 0 or an integer of 1 or more) and the like. These can be used alone or in combination.
Further, as the epoxy resin, a novolac-based epoxy resin, a biphenyl-based epoxy resin, and other known epoxy resins can be used in combination.

Examples of the (B) phenol resin used in the present invention include those having a skeleton structure represented by the following formula.

[0013]

[Chemical 6] (However, in the formula, n represents 0 or an integer of 1 or more)

[0014]

[Chemical 7] (However, in the formula, n represents 0 or an integer of 1 or more.) Further, this phenol resin is a novolac type phenol resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and modified products thereof. A resin can be used together.

As the inorganic filler (C) used in the present invention, those generally used are widely used. Among them, silica powder having a low impurity concentration and an average particle diameter of 30 μm or less is preferably used. . If the average particle size exceeds 30 μm, the moldability is deteriorated, which is not preferable. The blending ratio of the inorganic filler is preferably 25 to 90% by weight based on the total resin composition. 25% by weight
If it is less than 100% by weight, the resin composition has a high hygroscopicity and is inferior in moisture resistance after solder immersion, and if it exceeds 90% by weight, the fluidity is extremely poor and the moldability is inferior, which is not preferable.

As the curing accelerator (D) used in the present invention, a phosphorus curing accelerator, an imidazole curing accelerator, D
A wide range of BU-based curing accelerators and other curing accelerators can be used. These can be used alone or in combination of two or more kinds. It is desirable that the curing accelerator is blended in an amount of 0.01 to 5% by weight based on the total resin composition. If the proportion is less than 0.01% by weight, the gel time of the resin composition will be long and the curing characteristics will be poor, and if it exceeds 5% by weight, the fluidity will be extremely poor and the moldability will be poor.
Furthermore, the electrical characteristics are poor and the moisture resistance is poor, which is not preferable.

The epoxy resin composition of the present invention contains the above-mentioned specific epoxy resin, phenol resin, inorganic filler and curing accelerator as essential components. For example, natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides, esters, release agents such as paraffins, flame retardants such as antimony trioxide, colorants such as carbon black,
A silane coupling agent, a rubber-based or silicone-based low stress imparting agent, and the like can be appropriately added and blended.

A general method for preparing the epoxy resin composition of the present invention as a molding material is to mix the above-mentioned specific epoxy resin, phenol resin, inorganic filler, curing accelerator and other components, and mix with a mixer or the like. After sufficiently homogeneously mixing, a melt mixing process using a hot roll or a kneading process is further performed, followed by cooling and solidifying and pulverizing to an appropriate size to obtain a molding material. 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. After sealing with a molding material, it is heated and cured, and finally a semiconductor sealing device sealed with this cured product is obtained. For curing by heating, it is desirable to heat and cure at 150 ° C or higher.

[0020]

The epoxy resin composition and the semiconductor encapsulation device of the present invention, by using a specific epoxy resin or phenol resin, even if the epoxy resin contains 2 to 5% of a monomer, The glass transition temperature of the resin composition is increased, the mechanical properties and low stress properties are improved, the occurrence of resin cracks after solder immersion and solder reflow is eliminated, and deterioration of moisture resistance is reduced.

[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 10% of an epoxy resin having the above-mentioned structure of Chemical formula 4 and containing 5% of a monomer, 5% of a phenolic resin of Chemical formula 6 described above, 84% of silica powder, 0.3% of a curing accelerator, and an ester wax. 0.3% of silane coupling agent and 0.4% of silane coupling agent were mixed at room temperature, further kneaded and cooled at 90 to 95 ° C., and then pulverized to produce a molding material (A).

Example 2 The same structure as that used in Example 1 was obtained, and 5% was used.
Epoxy resin containing monomer 10.2%, the above-mentioned chemical 7
Phenol resin 4.8%, o-cresol novolac type epoxy resin 8%, silica powder 76%, curing accelerator 0.3%,
0.3% of ester waxes and silane coupling agent
0.4% was mixed at room temperature, further kneaded and cooled at 90 to 95 ° C., and then pulverized to produce a molding material (B).

Comparative Example 1 Epoxy resin 10% having the same structure as used in Example 1 and having a monomer content reduced to 1%, novolac type phenolic resin 5%, silica powder 84%, curing accelerator 0.3%
%, Ester waxes 0.3% and silane coupling agent 0.4% were mixed at room temperature, further kneaded and cooled at 90 to 95 ° C., and then pulverized to produce a molding material (C).

Comparative Example 2 Epoxy resin 10.2% having the same structure as that used in Example 1 and having the monomer content reduced to 1%, 4.8% of the phenol resin of Chemical formula 7 used in Example 2, silica powder 84%,
0.3% of curing accelerator, 0.3% of ester waxes and 0.4% of silane coupling agent are mixed at room temperature, and
After kneading and cooling at 95 ° C., it was pulverized to produce a molding material (D).

Molding materials (A) to (D) thus produced
Was used to transfer transfer into a mold heated to 170 ° C., and the semiconductor chip was sealed and cured to manufacture a semiconductor sealing device. Various tests were conducted on these semiconductor encapsulation devices, and the results are shown in Table 1. The epoxy resin composition and the semiconductor encapsulation device of the present invention have the same moisture resistance and solder as those of the epoxy resin containing less monomer. Since it has heat resistance and shows better fluidity than the epoxy resin containing less monomer, the remarkable effect of the present invention can be confirmed.

[0027]

[Table 1] * 1: Diameter 50 mm, thickness 3 mm by transfer molding
A molded article of the above was prepared, and the molded article was allowed to stand in 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 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: Using a molding material, a silicon chip with two or more aluminum wires is bonded to a normal 42 alloy frame and transfer molded at 175 ° C for 2 minutes.
Post-curing was performed at 175 ° C for 8 hours. The molded product thus obtained is subjected to moisture absorption treatment at 40 ° C., 90% RH for 100 hours in advance, and then
It was immersed in a solder bath at 250 ° C for 10 seconds. After that, 127 ℃,
PCT was performed in saturated steam of 2.5 atm and 50% disconnection due to corrosion of aluminum was evaluated as defective. * 5: QFP (14 × 14 × 1.4m) with 8 × 8mm dummy chip
m) It was placed in a package, transfer molding was performed for 2 minutes at 175 ° C using the molding material, and then post-curing was performed at 175 ° C for 8 hours. The semiconductor encapsulation device obtained in this way is 85 ℃, 85%,
After absorbing moisture for 24 hours, it was immersed in a solder bath at 240 ° C for 1 minute. After that, observe the package surface with a stereomicroscope,
The occurrence of external resin cracks was evaluated.

[0028]

As is clear from the above description and Table 1, the epoxy resin composition and the semiconductor encapsulation device of the present invention use the epoxy resin containing 2 to 5% of the monomer, Excellent in fluidity, moisture resistance and solder heat resistance,
The influence of moisture absorption is small, disconnection due to corrosion of electrodes and generation of leak current due to moisture can be significantly reduced, and reliability can be guaranteed for a long period of time.

Claims (2)

[Claims] 1. An epoxy resin represented by the following general formula (A): (However, in the formula, R ¹ is a t-butyl group, R ² is a methyl group,
R ³ represents a C ₁ H _{2l + 1} group, R ⁴ represents a C _m H _{2m + 1} group, and l, m and n in each group represent 0 or an integer of 1 or more.) (B) Phenolic resin ( C) Inorganic filler (D) Curing accelerator is an essential component, and the above (C) is used for the entire resin composition.
An epoxy resin composition, characterized by containing the inorganic filler according to the above in a proportion of 25 to 90% by weight. 2. An epoxy resin represented by the following general formula (A): (However, in the formula, R ¹ is a t-butyl group, R ² is a methyl group,
R ³ represents a C ₁ H _{2l + 1} group, R ⁴ represents a C _m H _{2m + 1} group, and l, m and n in each group represent 0 or an integer of 1 or more.) (B) Phenolic resin ( C) Inorganic filler (D) Curing accelerator is an essential component, and the above (C) is used for the entire resin composition.
A semiconductor encapsulation device, wherein a semiconductor chip is encapsulated with a cured product of an epoxy resin composition containing the inorganic filler in a proportion of 25 to 90% by weight.