JPH0753670A - Epoxy rein composition and sealed semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the subject composition, containing a specific epoxy resin, a novolak type phenolic resin and an inorganic filler as essential components, excellent in moisture, solder heat resistances, thermomechanical characteristics, etc., and useful for sealing, coating, insulating, etc., semiconductor devices, etc. CONSTITUTION:This resin composition contains (A) an epoxy resin expressed by the formula [R1 is CnH2n+1; (n) is 0 or an integer of >=1], (B) a novolak type phenolic resin and (C) an inorganic filler (preferably silica powder having <=30mum average particle diameter) in an amount of 25-90wt.% based on the resin composition as essential components.

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. 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 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, generation of internal resin cracks, disconnection due to electrode corrosion and leakage current due to moisture. It is the one we are trying to provide.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that by using a specific epoxy resin and a novolac type phenol resin as a curing agent, moisture resistance, solder It was found that a resin composition having excellent heat resistance and the like 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 3] (However, in the formula, R ¹ represents a C _n H _{2n + 1} group, and n in R ¹ represents 0 or an integer of 1 or more.) (B) a novolac type phenol resin and (C) an inorganic filler as essential components An epoxy resin composition characterized in that the inorganic filler (C) is contained in a proportion of 25 to 90% by weight with respect to the resin 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 (A) epoxy resin used in the present invention, the one represented by the above general formula is used, and the epoxy resin can be used without being restricted by its molecular weight and the like. As a specific compound, for example,

[0010]

[Chemical 4] Etc., and these can be used alone or in combination. In addition, a novolac-based epoxy resin, an epibis-based epoxy resin, and other generally known epoxy resins can be used in combination with this epoxy resin.

The novolak type phenolic resin (B) used in the present invention includes novolak type phenolic resins obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and modified resins thereof, for example, epoxidation. Or a butylated novolac type phenol resin, etc., and these can be used alone or in combination.
The compounding ratio of the novolac type phenol resin is the same as the above (A).
Molar ratio of the epoxy group (a) of (1) to the phenolic hydroxyl group (b) of (B) of the novolak type non-resin [(a) / (b)]
Is preferably in the range of 0.1 to 10. The molar ratio is 0.
If it is less than 1 or more than 10, the moisture resistance, the molding workability, and the electrical properties of the cured product deteriorate, and either case is not preferable.

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.

The epoxy resin composition of the present invention contains the above-mentioned specific epoxy resin, novolac type phenolic resin and inorganic filler as essential components, but within the range not deviating from the object of the present invention, and if necessary, For example, natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides, esters, paraffins and other release agents, antimony trioxide and other flame retardants, carbon black and other colorants,
A silane coupling agent, various curing accelerators, rubber-based or silicone-based low stress imparting agents, 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, novolac type phenol resin, inorganic filler and other components, and mix well with a mixer or the like. After uniformly mixing, a melt mixing process using a hot roll or a mixing process using a kneader or the like is further performed, and then the mixture is cooled and solidified and pulverized 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 molding material. The semiconductor device 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.

[0016]

In the epoxy resin composition and semiconductor encapsulation device of the present invention, the glass transition temperature of the resin composition is increased by using the specific epoxy resin and the novolac type phenol resin, and the thermomechanical characteristics and the low stress property are obtained. And the occurrence of resin cracks after solder dipping and solder reflow,
The moisture resistance is less deteriorated.

[0017]

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 16% of the epoxy resin shown in the above chemical formula 4, 8% of novolac type phenol resin (melting point 78 ° C.), 75% of silica powder, 0.3% of curing accelerator, 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 (A).

Example 2 Epoxy resin 8%, o-cresol novolac type epoxy resin 8%, novolac type phenolic resin 8%, silica powder 74%, curing accelerator 0.3%, ester waxes 0.3% And 0.4% of a 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 (B).

Comparative Example 1 o-Cresol Novolac type epoxy resin 17%, novolac type phenolic resin 8%, silica powder 74%, 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 20% epibis type epoxy resin (epoxy equivalent 450), 5% novolac type phenol resin, 74% silica powder, 0.3% curing accelerator, 0.3% ester waxes and 0.4% silane coupling agent at room temperature. And mix at 90-95 ℃
After kneading and cooling with, the mixture 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.

[0023]

[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., 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) 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.

[0024]

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): (However, in the formula, R ¹ represents a C _n H _{2n + 1} group, and n in R ¹ represents 0 or an integer of 1 or more.) (B) a novolac type phenol resin and (C) an inorganic filler as essential components An epoxy resin composition containing the inorganic filler (C) in a proportion of 25 to 90% by weight with respect to the resin composition. 2. An epoxy resin represented by the following general formula (A): (However, in the formula, R ¹ represents a C _n H _{2n + 1} group, and n in R ¹ represents 0 or an integer of 1 or more.) (B) a novolac type phenol resin and (C) an inorganic filler as essential components A semiconductor chip is sealed with a cured product of an epoxy resin composition containing the inorganic filler of (C) in a proportion of 25 to 90% by weight with respect to the resin composition. Stop device.