JP2002327043A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition enabling it to fill an inorganic filler therein by an amount higher than a conventional level and having an excellent fluidity, and to provide a semiconductor device obtained by sealing a semiconductor element using this epoxy resin composition. SOLUTION: In an epoxy resin composition comprising, essentially, (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator and (D) an inorganic filler, this epoxy resin composition is specified by that the relative standard deviation of the ratio of the peak area derived from the epoxy resin to that derived from the phenol resin, which is obtained by pyrolysis GC/MS(gas chromatography/mass spectrometry), is <=10 and the semiconductor device is obtained by sealing a semiconductor element using this composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for improving the fluidity,
The present invention also relates to an epoxy resin composition excellent in solder crack resistance due to high filling of an inorganic filler, and a semiconductor device using the epoxy resin composition.

[0002]

2. Description of the Related Art Conventionally, diodes, transistors, I
Semiconductor elements such as C and LSI have been sealed with an epoxy resin composition to protect them from external stimuli (mechanical / thermal shock, chemical action, etc.). However, while the degree of integration of semiconductor elements has been improved in recent years and their size has been increased, miniaturization and thinning of semiconductor devices due to recent downsizing of electronic devices have been demanded, and mounting methods on printed circuit boards have been conventionally used. There has been a shift from pin insertion to surface mount. However, problems such as cracks in semiconductor devices due to thermal shock during the surface-mounting soldering process and peeling of the interface between the chip / lead frame and the cured product of the epoxy resin composition occur. Strongly sought. It is believed that these cracks and peeling are caused by the semiconductor device itself before the soldering process absorbs moisture and the moisture causes a steam explosion at a high temperature during the soldering process. Techniques such as imparting low hygroscopicity are often used. As one of the techniques for reducing the moisture absorption, there is a technique in which a low-viscosity crystalline epoxy resin is used to highly fill an inorganic filler to reduce the content of a resin component. Conventionally, as an epoxy resin used in such a method, a biphenyl-type epoxy resin can be mentioned, which is often used for an epoxy resin composition in which an inorganic filler is highly filled. However, even if a crystalline epoxy resin having a low viscosity such as a biphenyl type epoxy resin is used, it is not easy to produce an epoxy resin composition containing an inorganic filler in an amount of 90% by weight or more. It was difficult to avoid deterioration. As a solution,
Although it is conceivable to use an epoxy resin having a lower viscosity than the biphenyl type epoxy resin, at present, a low molecular weight epoxy resin such as a bisphenol type epoxy resin must be used. However, these epoxy resins are liquid or semi-solid at room temperature, and the poor workability is a major drawback.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an epoxy resin composition which achieves a higher filling of inorganic fillers than before and has excellent fluidity, and encapsulating a semiconductor element with the epoxy resin composition. And a semiconductor device comprising:

[0004]

The present invention provides (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator,
(D) an epoxy resin composition containing an inorganic filler as an essential component, wherein the epoxy resin has a relative standard deviation of 10 or less in the ratio of the peak area derived from the epoxy resin to the peak area derived from the phenol resin by pyrolysis GC / MS. A composition and a semiconductor device in which a semiconductor element is sealed using the composition.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having two or more epoxy groups in one molecule, such as bisphenol A type epoxy resin and phenol novolak type epoxy resin. , Ortho-cresol novolak epoxy resin, naphthol novolak epoxy resin, triphenolmethane epoxy resin, dicyclopentadiene modified phenol epoxy resin, phenol aralkyl epoxy resin, terpene modified phenol epoxy resin,
Examples include, but are not limited to, biphenyl-type epoxy resins, hydroquinone-type epoxy resins, stilbene-type epoxy resins, and bisphenol-F-type epoxy resins. These epoxy resins may be used alone or as a mixture.

[0006] In order to improve the solder resistance of the semiconductor device, the amount of the inorganic filler in the resin composition is increased, and the cured product of the obtained resin composition has low moisture absorption, low thermal expansion, and high thermal expansion. In order to achieve strength, it is particularly preferable to use 30% by weight or more of a crystalline epoxy resin which exhibits crystallinity at room temperature and becomes a very low-viscosity liquid above its melting point in all epoxy resins. The melting point of the crystalline epoxy resin in the present invention indicates the temperature at the top of the endothermic peak of crystal melting at a temperature rising from room temperature at 5 ° C./min using a differential scanning calorimeter.

The phenolic resin used in the present invention refers to all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in one molecule.
Phenol novolak resin, cresol novolak resin, phenol aralkyl resin, terpene-modified phenol resin, dicyclopentadiene-modified phenol resin, naphthol aralkyl resin, triphenolmethane-type resin, bisphenol compound, and the like, but are not limited thereto. . Further, these phenol resins may be used alone or in combination. The softening point of the phenolic resin in the present invention was measured according to the ring and ball method of JIS K2406.

The most important point of the present invention is to uniformly disperse the epoxy resin (A) and the phenol resin (B) without deterioration of the resin. As a means for confirming the uniformity of the epoxy resin composition in the present invention, it has been found that measurement and evaluation of pyrolysis GC / MS are effective means. In the pyrolysis GC / MS, a sample put in a pyrolysis furnace is decomposed, vaporized, and gasified. The gas is separated by gas chromatography (GC). Each of the separated components is subjected to qualitative analysis by mass spectrometry (MS) to specify a substance. Table 1 shows the pyrolysis GC /
3 shows an example of a chart obtained by MS measurement. By performing this measurement, the peak area derived from the epoxy resin and the peak area derived from the phenol resin in the epoxy resin composition can be separated and assigned. At this time, the ratio of the assigned peak area derived from the epoxy resin to the peak area derived from the phenol resin is determined. Table 2 shows an example of the ratio of the peak area derived from the epoxy resin to the peak area derived from the phenol resin. This peak area ratio is semi-quantitative, and when the same material is measured a plurality of times, the peak area ratio becomes the same if dispersion is completely performed. Therefore, the uniformity of the epoxy resin composition can be confirmed by measuring the same epoxy resin composition a plurality of times, calculating the ratio in the same manner, and observing the variation. At this time, the variation can be quantified by calculating the relative standard deviation based on the measured result. The number of times of measurement in multiple measurements is 3 or more, preferably 5 or more, more preferably 10 or more. If the number of measurements is less than 3, an accurate relative standard deviation may not be obtained. The smaller the relative standard deviation, the better the dispersibility of the epoxy resin and the phenolic resin in the epoxy resin composition, and the relative standard deviation is preferably 10 or less. If it is larger than 10, the dispersibility of the epoxy resin and the phenol resin in the epoxy resin composition is insufficient, and a decrease in fluidity and curability is observed.

[0009]

[Table 1]

[0010]

[Table 2]

For uniform dispersion, it is important to mix the epoxy resin (A) and the phenol resin (B), but if the mixing method is such that uniform dispersion can be achieved without deterioration of the resin. There is no limitation on the method, but preferably, the component (A) and the component (B) are heated and melt-mixed, and after being melted, high-speed stirring or shearing is performed to perform fine dispersion in a short time. (A) an epoxy resin of the component,
In order to obtain a uniform molten mixture with the phenol resin of the component (B), there is a portion where the epoxy resin and the phenol resin are unevenly distributed only by the conventional mixing and stirring by heating and melting, and the epoxy resin and the phenol resin are sufficiently mixed. Not uniformly dispersed. Further, if mixing is continued for a long time in a heated and molten state in order to improve the dispersion, there is a possibility that the oxidative deterioration of the resin and the reaction proceed. Therefore, as a means for uniformly dispersing the epoxy resin and the phenol resin without deterioration, it is important to disperse the resin in a short time after melting the resin. As an example of a process for this, high-speed stirring is performed with an ultra-high-speed mixer, and a slit is provided around the mixer, so that the resin that is melted and stirred gives a shearing force when passing through the slit, thereby causing fine dispersion. For example, in a short time. This makes it possible to disperse the resin to the nano level in a short time without leaving the resin in a heated state for a long time after the epoxy resin and the phenol resin are melted. Improve properties such as improving fluidity due to viscosity decrease by dispersing the resin uniformly without deterioration, and improving curability and bending strength by improving the reactivity between epoxy resin and phenolic resin. The effect is obtained.

The curing accelerator used in the present invention includes:
A substance that can serve as a catalyst for a cross-linking reaction between the epoxy resin and the phenol resin. Specific examples include amine compounds such as tributylamine and 1,8-diazabicyclo (5,4,0) undecene-7, and triphenylphosphine. ,
Examples include organic phosphorus compounds such as tetraphenylphosphonium / tetraphenylborate salts, and imidazole compounds such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or as a mixture.

The inorganic filler used in the present invention includes, for example, fused silica, crystalline silica, alumina, silicon nitride, aluminum nitride and the like. When increasing the amount of the inorganic filler, fused silica is generally used. Fused silica can be used in either a crushed or spherical form. However, in order to increase the blending amount of the fused silica and to suppress an increase in the melt viscosity of the molding material, it is preferable to mainly use a spherical form. In order to further increase the blending amount of the spherical silica, it is desirable to adjust the particle size distribution of the spherical silica to be wider. The amount of the inorganic filler is preferably 80 to 95% by weight based on the entire epoxy resin composition. If it is less than 80% by weight, solder cracks may occur due to an increase in water absorption, and if it exceeds 95% by weight, the resin component may be too small and the fluidity during molding may be poor. A more preferred range is 85 to 93% by weight.

The epoxy resin composition of the present invention comprises (A)
In addition to the component (D), if necessary, a flame retardant such as a brominated epoxy resin, antimony oxide, or a phosphorus compound; an inorganic ion exchanger such as bismuth oxide hydrate; or a cup such as γ-glycidoxypropyltrimethoxysilane. Various colorants such as ring agents, carbon black, red iron oxide, etc., low stress components such as silicone oil and silicone rubber, release agents such as natural wax, synthetic wax, higher fatty acids and their metal salts or paraffin, various antioxidants, etc. Additives can be included.

Heating, melting and kneading can be carried out by a hot roll, a heating kneader or the like when compounding the above components to form a molding material, and cooling and pulverization are carried out using a device usually used for the production of molding materials. However, in order to more effectively and uniformly mix the epoxy resin and the phenol resin, it is preferable that the epoxy resin and the phenol resin are uniformly mixed in advance by dispersing and shearing like a homogenizer. More preferably, the epoxy resin and the phenol resin are melt-mixed, and the melt-mixed product is desirably dispersed and sheared like a homogenizer to perform uniform mixing in advance. This makes it possible to significantly reduce the relative standard deviation of the epoxy resin composition of the present invention by pyrolysis GC / MS. By using the epoxy resin composition of the present invention, even if the material is highly filled with an inorganic filler and a material using a low-viscosity epoxy resin or a curing agent, both components are previously blended as a very uniform composition. Therefore, it is possible to achieve both curability and fluidity in the molten and flowing state during molding, and it is possible to obtain a good molded product without causing defects such as unfilling during molding. . In order to manufacture a semiconductor device by encapsulating an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, the molding may be performed by a molding method such as a transfer mold, a compression mold, and an injection mold.

[0016]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 4.0 parts by weight of 3,3 ', 5,5'-tetramethylbiphenol type epoxy resin (melting point: 103 ° C., hereinafter referred to as epoxy resin), phenol aralkyl resin curing agent (softening point: 65) (C, hereinafter referred to as a curing agent) 3.5 parts by weight was heated to 115 ° C. and melt-mixed by the following method. When the epoxy resin and the phenol resin melt, CLEARMIX (M Technic Co., Ltd.)
15000 rpm using CLM-0.8S)
High-speed stirring and shearing were performed for minutes. After completion of the stirring, the mixture was cooled and pulverized to obtain a target resin composition (hereinafter, referred to as resin A). Next, they were blended in the following proportions, mixed with a heating roll at 80 ° C. for 5 minutes, cooled and pulverized to obtain an epoxy resin molding material. Table 3 shows the properties of the obtained forming materials.

Fused spherical silica (average particle size: 20 μm) 91.0 parts by weight Resin A 7.7 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 parts by weight Carbon black 0.2 parts by weight Carnauba wax 0.4 parts by weight Silicone oil 0.2 parts by weight γ-glycidoxypropyltrimethoxysilane 0.3 parts by weight

<Evaluation method> Dispersion evaluation of epoxy resin and phenol resin: A 1 mg granular sample of the resin composition was collected, and subjected to pyrolysis GC / MS (pyrolysis apparatus) under pyrolysis conditions of 590 ° C. × 10 seconds. :
PY-202D vertical heating furnace type pyrolysis apparatus manufactured by Frontier Lab, GC: HP-68 manufactured by Hewlett-Packard
90 type gas chromatograph, MS: HP-5973 type mass detector manufactured by Hewlett-Packard) Measurement was performed (n
= 10). The ratio of the peak area derived from the epoxy resin and the peak area derived from the phenol resin, which were assigned from the mass spectrum, was determined, and the relative standard deviation was determined as an index of the variation.
The greater the relative standard deviation, the greater the variation. Spiral flow: using a mold for spiral flow measurement according to EMMI-1-66, mold temperature 175
C., an injection pressure of 7 MPa, and a curing time of 2 minutes. The unit is cm. Gel time: The time from melting the epoxy resin composition to gelation on a hot plate at 175 ° C. was measured. The unit is seconds. Bacol hardness: mold temperature 175 ° C, injection pressure 7MPa,
The molded product was molded with a curing time of 2 minutes, and the surface hardness of the molded product 10 seconds after opening the mold was measured with a Bacol hardness tester # 935. -Torque value of a curast meter: Measured using a curast meter V type (manufactured by Orientec Co., Ltd.) at a 35φ die, an amplitude angle of 1 degree, and a molding temperature of 175 ° C. 90
The torque value after seconds was measured, and the curability was evaluated. The unit is N
m. Bending strength: JIS K 691 bending strength at 260 ° C
It measured according to 1. The unit is N / mm ² .

(Examples 2 to 4 and Comparative Examples 1 to 4) An epoxy resin composition was obtained in the same manner as in Example 1 in accordance with the blending in Table 1 (the blending ratio is by weight). It evaluated similarly. Table 1 shows the results. -Resin B (bisphenol A type epoxy resin (Formula (1)
(N = 0 body content: 96%, melting point: 45 ° C.) (hereinafter referred to as resin B) 4.9 parts by weight, and 2.9 parts by weight of a phenol novolak resin curing agent (softening point: 55 ° C.) to 115 ° C. Melt mixing was performed by the following method. When the epoxy resin and the phenol resin are melted, 15000 using CLEARMIX (manufactured by M-Technic Co., Ltd., CLM-0.8S).
rpm, high-speed stirring and shearing were performed for 1 minute. After completion of the stirring, the mixture was cooled and pulverized to obtain a target resin composition. -Resin C: A product obtained by melt-mixing and stirring at 130 rpm for 10 minutes at 125 ° C using a rotary blade in a flask with the same composition as resin A. -Resin D: A product obtained by melt-mixing and stirring at 130 rpm for 10 minutes at 125 ° C using a rotary blade in a flask with the same composition as resin B.

[0021]

Embedded image

[0022]

[Table 3]

[0023]

According to the present invention, there is provided an epoxy resin composition which achieves higher solder cracking resistance by realizing higher filling of the inorganic filler than before, and has excellent fluidity.
It is another object of the present invention to provide a highly reliable semiconductor device in which a semiconductor element is sealed with the epoxy resin composition.

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Claims (2)

[Claims] An epoxy resin composition comprising (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator, and (D) an inorganic filler as essential components.
An epoxy resin composition, wherein the relative standard deviation of the ratio of the peak area derived from the epoxy resin to the peak area derived from the phenol resin by S is 10 or less. 2. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to claim 1.