JPH07242736A - Epoxy resin composition and sealed semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition excellent in moisture resistance and soldering heat resistance by using as essential ingredients a specific epoxy resin, a specific phenolic resin, a given 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 CjH2j+1; R<2> is CkH2k+1; R<3> is CpH2p+1; and R<4> is CmH2m+1 (where j, k, p, m, and n each is 0, 1 or larger)], a phenolic resin represented by formula II (wherein R<5> is the same as R<1>, and R<6> is the same as R<2>), an inorganic filler (e.g. silica particles), and a curing accelerator (e.g. a phosphorus, imidazole, or BU compound). The amount of the filler is 25-90wt.% based on the whole 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 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, each lead pin has been soldered, but recently, a solder dipping method or a solder reflow method has been adopted.

A conventional semiconductor device sealed with a resin composition comprising an epoxy resin such as a novolac type epoxy resin, a novolac type phenol resin and silica powder has a drawback that the moisture resistance is lowered when the entire device is immersed in a solder bath. was there. Especially 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 cracking cause significant moisture resistance deterioration, which may cause wire breakage or moisture due to corrosion of the electrodes. A leak current is generated, and as a result, the semiconductor device has a drawback that it cannot guarantee long-term reliability.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks and has little influence of moisture absorption, and particularly excellent moisture resistance and solder heat resistance after immersion in a solder bath, and a sealing resin. Epoxy resin composition and semiconductor capable of ensuring long-term reliability without peeling between the semiconductor chip or the encapsulating resin and the lead frame and the occurrence of internal resin cracks, and without the occurrence of wire breakage due to electrode corrosion or leak current due to moisture. It is intended to provide a sealing device.

[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 phenol resin as a curing agent for a specific epoxy resin, moisture resistance, solder The present invention has been completed by finding that a resin composition having excellent heat resistance can be obtained.

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

[0007]

[Chemical 5] (However, in the formula, R ¹ is a C _j H _{2j + 1} group, and R ² is C _k H _{2k + 1.}
R ³ represents a C ₁ H _{2l + 1} group, R ⁴ represents a C _m H _{2m + 1} group, and j, k, l, m and n in each group are 0.
Or represents an integer of 1 or more) (B) Phenolic resin represented by the following general formula

[0008]

[Chemical 6] (However, in the formula, R ⁵ is a C _j H _{2j + 1} group and R ⁶ is a C _k H _{2k + 1 group.}
Each of which represents a group, and j, k and n in each group represent 0 or an integer of 1 or more). (C) An inorganic filler and (D) a curing accelerator are essential components, and ) An epoxy resin composition comprising an inorganic filler in a proportion 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, and the epoxy resin can be used without any particular limitation on the molecular weight and the like. As a specific compound, for example,

[0011]

[Chemical 7] (However, in the formula, n represents 0 or an integer of 1 or more)

[0012]

[Chemical 8] (However, in the formula, t-Bu represents a tertiary butyl group, n represents 0 or an integer of 1 or more), and the like, and these can be used alone or in combination of two or more kinds. Further, a novolac type epoxy resin, an epibis type epoxy resin, and other generally known epoxy resins can be used in combination with these epoxy resins.

As the (B) phenol resin used in the present invention, the phenol resin represented by the above general formula 6 can be used. As a specific compound, for example,

[0014]

[Chemical 9] Is mentioned. In addition to this phenol resin, 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 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. You can If the average particle size exceeds 30 μm, the moisture resistance and the moldability are 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.
When the proportion is less than 25% by weight, the hygroscopicity of the resin composition is large and the moisture resistance after solder immersion is poor, and when it exceeds 90% by weight, the fluidity is extremely poor 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 are widely used. These may be used alone or in combination of two or more. The mixing ratio of the curing accelerator is 0.01 with respect to the resin composition.
It is desirable that the compounding amount be 5% by weight. 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, and the electrical characteristics will also be poor and the moisture resistance will be poor. It is inferior in sex and is not preferable.

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 is necessary within a range not deviating from the object of the present invention. Depending on, 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, carbon black,
A colorant such as red iron oxide, a silane coupling agent, a rubber-based or silicone-based low stress imparting agent, and the like can be appropriately added and blended.

As a general method for preparing the epoxy resin composition of the present invention as a molding material, the above-mentioned specific epoxy resin, specific phenol resin, inorganic filler and curing accelerator and other components are prescribed. After mixing the raw material components selected in the composition ratio and mixing them sufficiently uniformly with a mixer or the like, melt mixing treatment with a hot roll or mixing treatment with a kneader etc. is further performed, followed by cooling and solidifying, and crushing to an appropriate size. It can be 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 molding material described above. 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 general 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 molding material is heated and cured at the time of sealing, and finally a semiconductor sealing device sealed with this cured product is obtained. Curing by heating is 150 ° C
It is desirable to heat and cure the above.

[0020]

The epoxy resin composition and the semiconductor encapsulation device of the present invention have the glass transition temperature of the resin composition increased by using the above-mentioned specific epoxy resin and phenol resin, so that the thermomechanical properties and the low stress can be reduced. Improved, solder immersion,
The generation of resin cracks after solder reflow is eliminated, and the 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 7.9% epoxy resin shown in Chemical formula 7, 7.1% phenolic resin shown in Chemical formula 9, 84% silica powder, 0.3% curing accelerator,
0.3% ester wax and silane coupling agent
0.4% was mixed at room temperature, further kneaded at 90 to 95 ° C., and cooled and ground to prepare a molding material (A).

Example 2 10.5% of the epoxy resin of Chemical formula 7 used in Example 1 and 9.5% of the phenolic resin of Chemical formula 9, silica powder 79.0%, a curing accelerator
0.3%, ester wax 0.3% and silane coupling agent 0.4% were mixed at room temperature, further kneaded at 90 to 95 ° C., and cooled and ground to prepare a molding material (B).

Comparative Example 1 o-Cresol Novolak type epoxy resin 13.1%, novolak type phenol resin 6.9%, silica powder 79%, curing accelerator 0.3%, ester wax 0.3% and silane coupling agent 0.4% were mixed and carried out. A molding material (C) was produced in the same manner as in Example 1.

Comparative Example 2 Epibis type epoxy resin (epoxy equivalent 450) 16.2%,
Novolac type phenol resin 3.8%, silica powder 79%,
0.3% of a curing accelerator, 0.3% of an ester wax and 0.4% of a silane coupling agent were mixed, further kneaded at 90 to 95 ° C., and cooled and ground to prepare a molding material (D).

Using the molding materials A) to (D) thus manufactured, transfer injection was carried out into a mold heated to 170 ° C. and cured to seal a semiconductor chip 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.

[0027]

[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 rate and
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 aluminum wirings is bonded to a normal 42 alloy frame and transfer molded at 175 ° C for 2 minutes.
Post curing was carried out at 8 ° C for 8 hours. The molded product thus obtained was previously subjected to moisture absorption treatment at 40 ° C., 95% RH for 100 hours, and then subjected to 250
It was soaked in a solder bath at ℃ for 10 seconds. After that, a humidity resistance test was conducted in saturated steam at 127 ° C and 2.5 atm to evaluate the time for 50% disconnection (defect occurrence) due to aluminum corrosion. * 5: QFP (14 x 14 x 1.4 m) with 8 x 8 mm dummy chip
m) Package and use molding compound for 2 at 175 ° C
After transfer molding for 1 minute, post-curing was performed at 175 ° C. for 8 hours. The semiconductor encapsulation device manufactured in this way is
After absorbing moisture for 85% for 24 hours, put it in a solder bath at 240 ℃ 1
Soaked for a minute. Then, the package surface was observed with a stereoscopic microscope to evaluate the presence or absence of external resin cracks.

[0028]

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 less susceptible to electrode corrosion. It is possible to remarkably reduce the occurrence of leakage current due to disconnection and moisture, and it is possible to guarantee the reliability for a long time.

Claims (2)

[Claims] 1. An epoxy resin represented by the following general formula (A): (However, in the formula, R ¹ is a C _j H _{2j + 1} group, and R ² is C _k H _{2k + 1.}
R ³ represents a C ₁ H _{2l + 1} group, R ⁴ represents a C _m H _{2m + 1} group, and j, k, l, m and n in each group are 0.
Or represents an integer of 1 or more) (B) Phenolic resin represented by the following general formula: (However, in the formula, R ⁵ is a C _j H _{2j + 1} group and R ⁶ is a C _k H _{2k + 1 group.}
Each of which represents a group, and j, k and n in each group represent 0 or an integer of 1 or more). (C) An inorganic filler and (D) a curing accelerator are essential components, and ) An epoxy resin composition comprising an inorganic filler 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 C _j H _{2j + 1} group, and R ² is C _k H _{2k + 1.}
R ³ represents a C ₁ H _{2l + 1} group, R ⁴ represents a C _m H _{2m + 1} group, and j, k, l, m and n in each group are 0.
Or represents an integer of 1 or more) (B) Phenolic resin represented by the following general formula: (However, in the formula, R ⁵ is a C _j H _{2j + 1} group and R ⁶ is a C _k H _{2k + 1 group.}
Each of which represents a group, and j, k and n in each group represent 0 or an integer of 1 or more). (C) An inorganic filler and (D) a curing accelerator are essential components, and ) A semiconductor encapsulation device characterized in that a semiconductor chip is encapsulated with a cured product of an epoxy resin composition containing an inorganic filler in a proportion of 25 to 90% by weight.