JP2002144331A - Method for manufacturing epoxy resin composition tablet and semiconductor device obtained by using the tablet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an epoxy resin composition tablet for obtaining a semiconductor device without any void by transfer molding while the semiconductor device obtained by the manufacturing method is provided. SOLUTION: The method for manufacturing the epoxy resin composition tablet is provided wherein when the epoxy resin composition tablet is manufactured by putting the epoxy resin composition powder into a mortar set in a tablet machine to be pressurized by an upper pestle, pressurizing is carried out while vibration is added to the mortar.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an epoxy resin composition tablet and a semiconductor device obtained by the method, and more particularly, to producing an epoxy resin composition tablet having a high filling factor. The present invention relates to a semiconductor device which can be manufactured by transfer molding using an epoxy resin tablet manufactured by this manufacturing method and has very few voids.

[0002]

2. Description of the Related Art Electronic circuit components such as semiconductor devices are required to be sealed in order to prevent damage from external contaminants and external pressure.

Conventional methods for sealing a semiconductor device include hermetic sealing using metal or ceramics, and resin sealing using an epoxy resin, a silicone resin, or a phenol resin, which is a thermosetting resin. Recently, in addition to the good formability of the package,
Resin encapsulation using an epoxy resin composition that is also excellent in reducing manufacturing costs has become the main focus.

Usually, transfer molding is used for resin sealing of a semiconductor device. This transfer molding
The molding is carried out using a transfer molding machine, and the epoxy resin composition tablet that has been tableted with a tableting machine is put into the pot of the molding machine, and is placed in a mold attached to the molding machine with the transfer of the molding machine. The resin sealing of the semiconductor device is performed by injecting a tablet-shaped epoxy resin composition under pressure and performing a heat treatment at a predetermined temperature for a predetermined time.
One of the problems that often occurs in transfer molding is that voids are generated in the obtained package. This may be caused by the resin entraining air when the mold is injected, volatilization of volatile components contained in the resin, and air remaining in the tablet. The voids generated due to these causes are not only bad in appearance but also cause water vapor to accumulate in the voids and impair the solder heat resistance.

Heretofore, as a countermeasure against the void, attempts have been made to reduce the volatile components in the resin as much as possible, to increase the resin viscosity, and to minimize the entrapment of air when the resin is injected into the mold. . However, the volatile components in the resin are mainly derived from the coupling agent in many cases, and when this is reduced, a disadvantage such as a decrease in the resin strength occurs, which leads to a decrease in solder heat resistance. Further, when the resin viscosity is increased to suppress the entrapment of air at the time of injecting the resin into the mold, there is a drawback that problems such as unfilling and wire flow occur particularly in thin packages such as TSOP and LQFP. Also, a thick QFP often causes similar problems depending on the design.

[0006]

SUMMARY OF THE INVENTION The present invention has been achieved as a result of studying to solve the problems in the prior art described above.

Accordingly, it is an object of the present invention to provide a method for producing an epoxy resin composition tablet for obtaining a void-free semiconductor device by transfer molding and a semiconductor device obtained by the method.

[0008]

In order to achieve the above-mentioned object, the present invention mainly has the following constitution. That is, "the powder of the epoxy resin composition, put into a die provided in a tableting machine, pressurized with an upper punch, when producing an epoxy resin composition tablet, pressurizing while applying vibration to the die. And a method for producing an epoxy resin composition tablet. "

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and effects of the present invention will be described below in detail.

First, a method for manufacturing a semiconductor device according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a main part of a tableting machine used in the production method of the present invention. However, FIG. 1 shows a general example of a tableting machine. As the tableting machine, a commercially available tableting machine can be used, and a vibration generator as described later is mounted on a die of the tableting machine. Just attach it.

In FIG. 1, 1 is an upper punch, 2 is a lower punch, and 3 is a die. The epoxy resin composition powder is put in the mold 3 and pressed by the upper punch 1, so that an epoxy resin tablet is obtained.

Here, the die 3 is provided with a vibrator (not shown),
A predetermined vibration is given in the direction of the arrow by a vibration generator such as a spring, a flywheel, a cam, a mainspring, etc., and the microvibration is repeated. The frequency is not particularly limited, but is preferably 1 to 1000 KHz, more preferably 20 to 10 KHz.
00 KHz. The output is not particularly limited, but is preferably 10 to 3000 W, and more preferably 100 to 2000 W.

[0014] Therefore, the epoxy resin composition tablet can be compressed in the die 3 at a high density, and the amount of air in the tablet can be suppressed. You can get no package.

The direction of the vibration applied to the mill 3 is not particularly limited, but it is preferable that the vibration is applied in the pressing direction of the upper punch 1 as shown in the figure.

Next, the epoxy resin composition used in the present invention will be described.

The epoxy resin composition used in the present invention comprises:
An epoxy resin (A), a curing agent (B) and an inorganic filler (C) are contained as essential components.

The epoxy resin (A) is not particularly limited to a resin having an epoxy group in a molecule.
Specific examples thereof include bisphenol A type epoxy resin, bisphenol C type epoxy resin, hydrogenated bisphenol type epoxy resin, bisphenol F type novolak resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, and alicyclic ring such as cyclopentadiene ring. Examples include a structure-containing epoxy resin, a biphenyl-type epoxy resin, and an epoxy-modified organosilicone. These epoxy resin compositions can be used alone or in combination of two or more.

The curing agent (B) is an epoxy resin (A)
Phenol novolak resin, cresol novolak resin, phenol p-xylylene copolymer, various novolak resins synthesized from bisphenol A or resorcinol, and various types of resins. Examples thereof include acid anhydrides such as polyhydric phenol compounds, maleic anhydride, phthalic anhydride and pyromellitic anhydride, and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone.

Two or more of these curing agents (B) may be used in combination depending on the use, and the amount of the curing agent (B) is 0.5 to 1.5 (the equivalent of the curing agent is equivalent to the epoxy resin (A)). /
(Epoxy equivalent) is preferable, and particularly preferably in the range of 0.8 to 1.2.

Specific examples of the inorganic filler (C) include:
Fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, metal oxides such as antimony oxide, asbestos, glass fibers and glass spheres, among others. However, fused silica is particularly preferably used because it has a great effect of lowering the coefficient of thermal expansion and is effective in reducing the stress.

The blending ratio of the inorganic filler (C) is not particularly limited, but from a viewpoint of reliability and moldability, it is a high ratio of 79 to 98% by weight, preferably 84 to 92% based on the whole composition. May be contained. The shape of the filler is not particularly limited, but is preferably spherical. Further, those having a particle size distribution are preferred.

The epoxy resin composition may further contain the following additives as required, in addition to the epoxy resin (A), the curing agent (B) and the inorganic filler (C). .

Various waxes such as polyethylene wax, carbana wax, montanic acid wax and magnesium stearate, metal salts of fatty acids, long-chain fatty acids,
Various release agents such as metal salts of long-chain fatty acids, esters or amides of long-chain fatty acids and various modified silicone compounds,
Glycidyl ether of brominated bisphenol A, halogenated epoxy resin such as brominated cresol novolak,
Flame retardants such as organic halogen compounds and phosphorus compounds, various flame retardant aids such as antimony trioxide, diantimony tetroxide and antimony pentoxide, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-glycid Xypropyltrimethoxysilane, γ-glycidoxypropylvinylethoxysilane,
γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, aminopropyltrimethoxysilane, amino Propyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltriethoxysilane, γ-
Anilinopropyltrimethoxysilane, γ-anilinopropyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane and N-β- (N-vinylbenzylaminoethyl)- Various silane coupling agents such as γ-aminopropyltriethoxysilane, triphenylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tri-a-tolylphosphine, tris- (2,6-
Various phosphine compounds such as dimethoxyenol) phosphine, various phosphonium salts such as tetraphenylphosphonium bromide, tetraethylphosphonium bromide, tetrabutylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, tetraethylphosphonium tetraphenylborate and tetrabutylphosphonium tetraphenylborate, And imidazole, 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 1-phenylimidazole, 2-phenylimidazole, 1-benzylimidazole, 1,8-diaza-bicyclo- (5,4,
0) Undecene-7 (DBU), phenol of DBU,
DBU phenol novolak salt, DBU octyl salt, D
BUp-toluenesulfonate and 1,5-diaza-
Various curing accelerators such as various amine compounds such as bicyclo (4,3,0) nonene-5 (DBN); various coloring agents such as carbon black and iron oxide; various pigments; silicone rubber; olefin-based copolymers; Nitrile rubber,
Various elastomers such as modified polybutadiene rubber, various thermoplastic resins such as polyethylene, and crosslinking agents such as organic peroxides.

The above epoxy resin composition is prepared by mixing an epoxy resin (A), a curing agent (B), an inorganic filler (C) and other additives with, for example, a Banbury mixer or the like, and then mixing the mixture with a monoaxial or biaxial resin. Melt kneading is performed using various kneaders such as an extruder, a kneader and a hot roll. Thereafter, after cooling and pulverizing, the obtained epoxy resin composition powder is used to obtain an epoxy resin tablet using a tableting machine.

Then, the semiconductor is encapsulated by transfer molding the above epoxy resin composition tablet using a molding machine to obtain a semiconductor device. The epoxy resin composition tablet obtained by the production method of the present invention shows a high filling factor, and transfer molding is performed using the tablet obtained by this production method, and the resulting package has voids which are considered to lead to a decrease in reliability. Few.

[0027]

EXAMPLES The effects of the present invention will be described more specifically with reference to examples and comparative examples.

[Examples 1 to 7 and Comparative Examples 1 to 4] The raw materials shown in Table 1 were dry-blended using a mixer at the composition ratios shown in Tables 2 to 5. This is extruded for 4 minutes
After melt-kneading at 90 ° C., the mixture was cooled and pulverized to prepare a powder of the epoxy resin composition.

Each of the above epoxy resin composition powders was molded using the tableting machine shown in FIG. 1 to obtain an epoxy resin composition tablet. By transfer molding using this tablet, a molding temperature of 175 ° C., a molding time of 120 seconds, an injection speed of 12 seconds, and an injection pressure of 70 kgf / cm ^2.
To obtain a package (160-pin QFP below).

Table 1 shows the results of evaluating the performance of the obtained semiconductor device according to the following evaluation criteria.

The vibration to the mortar was applied in a direction parallel to the pressing direction of the upper punch (in the direction of the arrow in the drawing) at a power of 1500 W using a ferrite vibrator, and the vibration frequencies are shown in Tables 2 to 5. . In Comparative Examples 1 to 5, tableting was performed by a general tableting method without giving vibration to the mortar.

[Evaluation Criteria] Tablet size: 6.0 cm diameter, 85.0 g Final tableting pressure: 500 kgf / cm ² Holding time at final tableting pressure: 3 seconds Tablet filling rate: The tablet filling rate was determined by the following method. . Tablet filling rate (%) = (4 × w × 100) / (d ² × h × π
× ρ) where w is tablet weight (g), d is tablet diameter (cm), h is tablet height (cm), π is pi,
ρ is specific gravity (g / cm ³ ). Here, as a specific gravity, the molded cured product of the doublet is cut into a rectangular parallelepiped,
The value obtained by the Archimedes method was used.

Number of voids: A package of 160 pins QFP was molded into 50 packages, the internal voids were observed with an ultrasonic flaw detector, and the external voids were visually observed, and the total was divided by 50 to determine the number of voids per package. . 160-pin QFP: external dimensions 28 x 28 x 3.4 mm, chip size 11 x 11 mm, die pad size 13 x 13 mm

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

As is clear from the results in Tables 2 to 4, tablets obtained by the method of the present invention (Examples 1 to 6)
Shows that the filling rate is higher than that of Comparative Examples 1 to 3 obtained by a method in which vibration is not applied to the mortar. It turns out that the package obtained by transfer molding using the tablet obtained by the manufacturing method of the present invention has very few voids.

[0038]

As described above, according to the method for producing an epoxy resin composition tablet of the present invention, a tablet having a high filling factor can be obtained. As a result, transfer molding using the tablet obtained by the method of the present invention can be performed. Thus, a semiconductor device having less voids and excellent moldability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a main part of a tableting machine used in a production method of the present invention.

[Explanation of symbols]

 1: upper punch 2: lower punch 3: die 4: tablet (epoxy resin composition)

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Claims (5)

[Claims] 1. An epoxy resin composition powder is put into a die provided in a tableting machine, and is pressed by an upper punch. When manufacturing an epoxy resin composition tablet, the powder is pressed while vibrating the die. A method for producing an epoxy resin composition tablet. 2. The method for producing an epoxy resin composition tablet according to claim 1, wherein a vibration is applied in a pressing direction of the upper punch. 3. The vibration frequency applied to the mortar is 10 to 1000.
The method for producing an epoxy resin composition tablet according to claim 1, wherein the frequency is kHz. 4. The epoxy resin composition contains an epoxy resin (A), a curing agent (B) and an inorganic filler (C) as essential components, and the content of the inorganic filler (C) is at least 79% by weight. The method for producing an epoxy resin composition tablet according to claim 1, wherein: 5. A semiconductor device obtained by transfer molding using an epoxy resin composition tablet produced by the production method according to claim 1.