JPH11263897A - Epoxy resin composition and sealed semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin compsn. excellent in resistances to moisture and soldering heat by compounding an epoxy resin comprising two resins in a specified ratio with a phenol aralkyl resin, a specified amt. of an inorg. filler, and a cure accelerator. SOLUTION: This compsn. contains, as essential ingredients, an epoxy resin comprising (A) an epoxy resin of formula I (wherein n is an integer of 0 or higher) and (B) an epoxy resin of formula II (wherein R<1> to R<4> are each H or a 1-10C alkyl) in a wt. ratio of A/B of 1-10, a phenol aralkyl resin of formula II (wherein n is an integer of 0 or higher), an inorg. filler in an amt. of 25-93 wt.% of the compsn., and a cure accelerator. In addition to a phenol aralkyl resin, a novolak phenol resin obtd. by reacting a phenol with formaldehyde or paraformaldehyde and a modification thereof may be jointly used. A silica powder having an average particle size of 30 μm or lower is pref. as the filler.

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 excellent in moisture resistance and solder heat resistance, and a semiconductor sealing device in which a semiconductor chip is sealed 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 the development of high integration and high reliability technologies, automation of the mounting process of semiconductor devices has been promoted. For example, when a flat package type semiconductor device is mounted on a circuit board, soldering has conventionally been performed for each lead pin, but recently, a solder immersion 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 novolak type epoxy resin, a novolak type phenol resin and silica powder has a disadvantage that the moisture resistance is reduced when the entire device is immersed in a solder bath. was there. In particular, when a semiconductor device that has absorbed moisture is immersed, peeling between the sealing resin and the semiconductor chip, or between the sealing resin and the lead frame and internal resin cracks occur, causing significant moisture resistance deterioration, disconnection due to electrode corrosion, and disconnection due to electrode corrosion or moisture. Leakage current occurs, and as a result, the semiconductor device has a disadvantage that long-term reliability cannot be guaranteed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and has a small influence of moisture absorption, and particularly has excellent moisture resistance after IR reflow and excellent solder heat resistance.
Epoxy resin composition that can guarantee long-term reliability without peeling between the sealing resin and the semiconductor chip or between the sealing resin and the lead frame, no internal resin cracking, no disconnection due to electrode corrosion, and no leakage current due to moisture An object and a semiconductor sealing device are provided.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, by using a specific epoxy resin and a specific phenol resin, it was possible to reduce the viscosity and toughen the resin. The present invention has been found to realize a resin composition having excellent moldability, moisture resistance and solder heat resistance, and has completed the present invention.

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

[0007]

Embedded image (Wherein, n represents 0 or an integer of 1 or more) (b) an epoxy resin represented by the following general formula:

[0008]

Embedded image (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms). (B) a phenol aralkyl resin represented by the following general formula:

[0009]

Embedded image (Wherein, n represents 0 or an integer of 1 or more) (C) an inorganic filler and (D) a curing accelerator are essential components, and the (C) inorganic filler is added to the resin composition in an amount of 25%. An epoxy resin composition characterized in that it is contained in a proportion of up to 93% by weight. Yet another invention is
A semiconductor sealing device 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.

The epoxy resin (A) used in the present invention contains the component (a) represented by the general formula (7) and the component (b) represented by the chemical formula (8). , (A) component / (b) component in a weight ratio of 1 to 10. If the ratio is less than 1, cavities are formed in the molded product, and the moldability is deteriorated, which is not preferable. If the ratio is more than 10, the viscosity cannot be reduced and the toughness cannot be obtained, which is not preferable. In addition, a novolak epoxy resin, an epibis epoxy resin, and other commonly known epoxy resins can be used in combination with the epoxy resin.

As the phenol aralkyl resin (B) used in the present invention, those represented by the aforementioned general formula 9 are used. As specific compounds, for example,

[0013]

Embedded image

[0014]

Embedded image

[0015]

Embedded image And the like. In addition to the phenol aralkyl resin, a novolak-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 fillers 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. Can be. If the average particle size exceeds 30 μm, the moisture resistance and the moldability are poor, which is not preferable. The mixing ratio of the inorganic filler is 25 to 93% by weight based on the whole resin composition. The ratio is 25
When the amount is less than the weight percentage, the resin composition has a large hygroscopicity and is inferior in the moisture resistance after immersion in the solder. When the amount exceeds 93% by weight, the fluidity is extremely deteriorated and the moldability is inferior.

The (D) curing accelerator used in the present invention includes a phosphorus-based curing accelerator, an imidazole-based curing accelerator,
BU-based curing accelerators and other curing accelerators are widely used. These can be used alone or in combination of two or more. The compounding ratio of the curing accelerator is 0.01% with respect to the resin composition.
It is desirable to mix them so as to contain up to 5% by weight. If the proportion is less than 0.01% by weight, the gel time of the resin composition is long and the curing property is deteriorated. If it exceeds 5% by weight, the fluidity is extremely deteriorated, the moldability is deteriorated, and the electric properties are also deteriorated, and the moisture resistance is deteriorated. Inferior in properties and not preferred.

The epoxy resin composition of the present invention contains the above-mentioned specific epoxy resin, specific phenol resin, inorganic filler and curing accelerator as essential components. Depending on, for example, natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters, release agents such as paraffins, flame retardants such as antimony trioxide, carbon black,
A coloring agent such as redwood, 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, a specific epoxy resin, a specific phenol resin, an inorganic filler, a curing accelerator and other components described above are added to a predetermined component. After blending the raw material components selected in the composition ratio and mixing sufficiently uniformly with a mixer or the like, further perform a melt mixing treatment with a hot roll or a mixing treatment with a kneader or the like, then solidify by cooling, and pulverize to an appropriate size. It can be a molding material. If the molding material thus obtained is applied to sealing, coating, insulating, 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 molding material is heated and cured at the time of sealing, and finally a semiconductor sealing device sealed with the cured product is obtained. 150 ° C for curing by heating
It is desirable to cure by heating as described above.

[0021]

The epoxy resin composition and the semiconductor encapsulation device of the present invention realize low viscosity and high toughness by using the above-mentioned specific epoxy resin and specific phenol resin, and absorb water of the resin composition. This improves heat-mechanical properties and low-stress properties, eliminates the occurrence of resin cracks after solder immersion and solder reflow, and reduces moisture resistance deterioration.

[0022]

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 The above-mentioned (a) epoxy resin of the formula (7) 5.8%, the (b) epoxy resin of the above-mentioned formula (8) 1.0%, the phenol aralkyl resin of the above formula (4) 4.8%, the silica powder 88%, the curing acceleration 0.3% of an agent, 0.3% of an ester wax and 0.4% of a silane coupling agent were mixed at room temperature, kneaded at 90 to 95 ° C, and cooled and pulverized to produce a molding material (A).

Example 2 6.1% of the epoxy resin (a) used in Example 1 and 0.8% of the epoxy resin (b) used in Example 1 were used in Example 1.
2.9% phenol aralkyl resin, 1.1% phenol novolak resin, 88% silica powder, curing accelerator 0.3
%, Ester wax 0.3% and silane coupling agent 0.4% were mixed at room temperature, kneaded at 90-95 ° C., and cooled and pulverized to produce a molding material (B).

Comparative Example 1 10% of an epoxy resin (a) of Chemical formula 7, 7% of a phenol aralkyl resin of Chemical formula 10, 82% of silica powder, and a curing accelerator 0.3
%, Ester wax 0.3% and silane coupling agent 0.4% were mixed, further kneaded at 90 to 95 ° C., and cooled and pulverized to produce a molding material (C).

Comparative Example 2 Biphenyl type epoxy resin 9%, phenol aralkyl resin of formula 10 8%, silica powder 82%, curing accelerator 0.3
%, Ester wax 0.3% and silane coupling agent 0.4% were mixed, further kneaded at 90 to 95 ° C., and cooled and pulverized to produce a molding material (D).

The molding materials (A) to (D) thus produced
Was used to transfer and inject into a mold heated to 175 ° C. and cured to seal the semiconductor chip, thereby producing a semiconductor sealing device. Various tests were performed on these semiconductor sealing devices, and the results are shown in Table 1. The epoxy resin composition and the semiconductor sealing device of the present invention are excellent in moisture resistance and solder heat resistance. The remarkable effect of the invention could be confirmed.

[0028]

[Table 1] * 1: A molded product with a diameter of 50 mm and a thickness of 3 mm was prepared by transfer molding, left in saturated steam at 127 ° C and 2.5 atm for 24 hours, and measured by the increased weight. * 2: A molded product similar to that in the case of water absorption was prepared, post-cured at 175 ° C for 8 hours, and a test piece of appropriate size was measured using a thermomechanical analyzer. * 3: Tested according to JIS-K-6911. * 4: (number of nests, number of PKGs) / (total number of PKGs) × 100 * 5: Put 8 × 8 mm dummy chips in a QFP (14 × 14 × 1.4 mm) package and use molding material at 175 ° C. After transfer molding for 2 minutes, post-curing was performed at 175 ° C. for 8 hours. The semiconductor encapsulation device thus manufactured was subjected to a moisture absorption treatment at 85 ° C., 60% for 168 hours, and then passed through IR reflow at 240 ° C. three times. Then, the surface of the package was observed with a stereomicroscope to evaluate the occurrence of external resin cracks. * 6: Using a molding material, a silicon chip with two aluminum wirings is bonded to a normal 42 alloy frame, transfer molded at 175 ° C for 2 minutes, and post-cured at 175 ° C for 8 hours. Was. The molded article thus obtained was previously subjected to a moisture absorption treatment at 40 ° C., 90% RH and 100 hours, and then passed through IR reflow at 240 ° C. three times. Then, a moisture resistance test was performed in saturated steam at 127 ° C and 2.5 atm to evaluate the time at which 50% disconnection (failure) due to aluminum corrosion occurred.

[0029]

As is clear from the above description and Table 1, the epoxy resin composition and the semiconductor encapsulation device of the present invention are excellent in moisture resistance and solder heat resistance, are less affected by moisture absorption, and are less affected by electrode corrosion. The occurrence of leakage current due to disconnection or moisture can be significantly reduced, and reliability can be guaranteed for a long time.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 61/06 C08L 61/06 H01L 23/29 H01L 23/30 R 23/31

Claims (2)

[Claims] (A) (a) an epoxy resin represented by the following general formula: (Wherein, n represents 0 or an integer of 1 or more) (b) An epoxy resin represented by the following general formula: (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms). (B) a phenol aralkyl resin represented by the following general formula: (Wherein, n represents 0 or an integer of 1 or more) (C) an inorganic filler and (D) a curing accelerator are essential components, and the (C) inorganic filler is added to the resin composition in an amount of 25%. An epoxy resin composition characterized in that it is contained in a proportion of up to 93% by weight. (A) (a) an epoxy resin represented by the following general formula: (Wherein, n represents 0 or an integer of 1 or more) (b) An epoxy resin represented by the following general formula: (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms). (B) a phenol aralkyl resin represented by the following general formula: (Wherein, n represents 0 or an integer of 1 or more) (C) an inorganic filler and (D) a curing accelerator are essential components, and the (C) inorganic filler is added to the resin composition in an amount of 25%. A semiconductor sealing device, wherein a semiconductor chip is sealed with a cured product of an epoxy resin composition contained in a proportion of about 93% by weight.