JPH07242730A - 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 a specific epoxy resin, a specific 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, a phenolic resin represented by formula II (wherein R<1> is a group represented by CjH2j+1; R<2> is a group represented by CkH2k+1; and j, k, and n each is an integer of 0 or larger), an inorganic filler, e.g. silica particles having an average particle diameter of 30mum or smaller, and a curing accelerator, e.g. a phosphorus or imidazole compound, the amount of the filler being 25-90wt.% based on the whole composition. This device is obtained by sealing a semiconductor chip with this composition and curing the 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 having excellent moisture resistance and solder heat resistance, and a semiconductor encapsulation device.

[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 semiconductor device sealed with a conventional resin composition comprising an epoxy resin such as a novolac type epoxy resin, a novolac type phenolic resin and silica powder has a moisture resistance when the entire device is immersed in a solder bath. There was a drawback that the property deteriorated. Especially when a semiconductor device that has absorbed moisture is immersed, peeling between the encapsulating resin and the semiconductor chip, or between the encapsulating resin and the lead frame, and internal resin cracks cause significant deterioration in moisture resistance, which may cause wire breakage or moisture due to electrode corrosion. Leakage current, resulting in
The semiconductor device has a drawback in that it 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 and solder heat resistance after immersion in a solder bath, and has a sealing resin and a semiconductor chip or sealing. Epoxy resin composition and semiconductor encapsulation device capable of ensuring long-term reliability without peeling between resin and lead frame or internal resin cracks, and without breakage due to electrode corrosion or leakage current due to moisture It is what

[0005]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventor has found that by using a specific epoxy resin and a specific phenol resin as a curing agent, moisture resistance and solder heat resistance can be improved. It was found that a resin composition having excellent properties can be obtained, 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 5] (B) Phenolic resin represented by the following general formula

[0008]

[Chemical 6] (However, in the formula, R ¹ is a C _j H _{2j + 1} group, and R ² is C _k H _{2k + 1.}
Represents a group, and j and k in each group and n are
0 or an integer of 1 or more) (C) an inorganic filler and (D) a curing accelerator are essential components, and the above (C) is used for the entire resin composition.
An epoxy resin composition comprising the inorganic filler of 25 to 90% 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 5 is used. A novolac-based epoxy resin, an epibis-based epoxy resin, and other known epoxy resins can be used in combination with this epoxy resin.

As the (B) phenol resin used in the present invention, those represented by the above general formula 6 can be used. Specific compounds include, for example,

[0012]

[Chemical 7] Is mentioned. In addition to this phenol resin, a novolac type phenol resin obtained by reacting phenols such as fail and alkylphenol with formaldehyde or paraformaldehyde and modified resins thereof can be used in combination.

As the inorganic filler (C) used in the present invention, generally used ones 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 moisture resistance and moldability are poor, which is not preferable. The blending ratio of the inorganic filler is 25 to 90 with respect to the entire resin composition.
It is preferable to mix them so as to contain them by weight. When the proportion is less than 25% by weight, the hygroscopicity of the resin composition is high and the moisture resistance after solder immersion is poor, and when it exceeds 90% by weight, the fluidity is extremely deteriorated and the moldability is poor, which is not preferable.

As the curing accelerator (D) used in the present invention, a phosphorus curing accelerator, an imidazole curing accelerator, D
BU-based curing accelerators and other curing accelerators can be widely 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 properties will be poor, and if it exceeds 5% by weight, the fluidity will be extremely poor and the moldability will be poor and the electrical properties will be poor and the moisture resistance will be poor. Unfavorably poor.

The epoxy resin composition of the present invention contains the above-mentioned specific epoxy resin, specific phenolic resin, inorganic filler and curing accelerator as essential components, but it is also necessary as long as the object of the present invention is not impaired. Depending on, for example,
Natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides, esters, release agents such as paraffin, flame retardants such as antimony trioxide, colorants such as carbon black, silane coupling agents, rubbers A silicone-based low stress-imparting agent or 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 to add the above-mentioned specific epoxy resin, specific phenol resin, inorganic filler, curing accelerator and other components, A molding material can be obtained by sufficiently uniformly mixing with a mixer or the like, further performing melt mixing treatment with a hot roll or mixing treatment with a kneader, and then cooling and solidifying and pulverizing to an appropriate size. 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.

[0018]

In the epoxy resin composition and semiconductor encapsulation device of the present invention, by using a specific epoxy resin or a specific phenol resin, the glass transition temperature of the resin composition rises, and the thermomechanical properties and low stress properties are improved. It is improved, the occurrence of resin cracks after solder immersion and solder reflow is eliminated, and the deterioration of moisture resistance is reduced.

[0019]

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 6.0% of the above-mentioned epoxy resin of Chemical formula 5, 6.0% of the above-mentioned phenolic resin of Chemical formula 7, 87% of silica powder, 0.3% of curing accelerator
%, 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 (A).

Example 2 10.1% of the epoxy resin of Chemical formula 5 used in Example 1, Example 1
Chemical formula 7 phenolic resin 9.9%, silica powder 79
%, Curing accelerator 0.3%, ester waxes 0.3% and silane coupling agent 0.4% are mixed at room temperature, and
The mixture was kneaded and cooled at 90 to 95 ° C, and then pulverized to produce a molding material (B).

Comparative Example 1 o-Cresol Novolac type epoxy resin 13.1%, novolac type phenol resin 6.9%, silica powder 79%, curing accelerator 0.3%, ester waxes 0.3% and silane coupling agent 0.4% are mixed at room temperature. After further kneading and cooling at 90 to 95 ° C., the mixture was pulverized to produce a molding material (C).

Comparative Example 2 Epibis-type epoxy resin (epoxy equivalent 450) 16.2%,
Novolac-type phenol resin 3.8%, silica powder 79%,
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 are excellent in moisture resistance and solder heat resistance. The remarkable effect of the invention could be confirmed.

[0025]

[Table 1] * 1: Diameter 50 mm, thickness 3 mm by transfer molding
The molded product of No. 1 was prepared, and it was left 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., 95% 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) The package was placed, 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 obtained in this way was used at 85 ℃, 85%, 24
After absorbing moisture for a period of time, it was immersed in a solder bath at 240 ° C for 1 minute. Then, the package surface was observed with a stereoscopic microscope to evaluate the presence or absence of external resin cracks.

[0026]

As is clear from the above description and Table 1, the epoxy resin composition and the semiconductor encapsulation device of the present invention have excellent moisture resistance and solder heat resistance, are less affected by moisture absorption, and are not affected by electrode corrosion. It is possible to remarkably reduce the generation of leakage current due to disconnection and moisture, and it is possible to guarantee the reliability for a long period of time.

Claims (2)

[Claims] 1. An epoxy resin represented by the following general formula (A): (B) Phenolic resin represented by the following general formula: (However, in the formula, R ¹ is a C _j H _{2j + 1} group, and R ² is C _k H _{2k + 1.}
Represents a group, and j and k in each group and n are
0 or an integer of 1 or more) (C) an inorganic filler and (D) a curing accelerator are essential components, 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): (B) Phenolic resin represented by the following general formula: (However, in the formula, R ¹ is a C _j H _{2j + 1} group, and R ² is C _k H _{2k + 1.}
Represents a group, and j and k in each group and n are
0 or an integer of 1 or more) (C) an inorganic filler and (D) a curing accelerator are essential components, 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.