JP3308397B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

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 for semiconductor encapsulation.

[0002]

2. Description of the Related Art In recent years, the tendency of semiconductor devices to become larger and more highly integrated has increased. When a semiconductor is sealed with a conventional epoxy resin composition, the difference in linear expansion coefficient between the chip or lead frame and the sealing resin is increased. There is a problem that the reliability of the semiconductor component is reduced, for example, a crack is generated in the chip due to the thermal stress generated by the heat or the bonding wire is cut. In addition, along with the high integration of semiconductor mounting, a method of immersing a resin-encapsulated semiconductor in molten solder or mounting it with an infrared reflow device or the like has been adopted. There was a problem of generating cracks.

In order to reduce thermal stress and to prevent package cracks occurring during mounting, it is effective to increase the content of an inorganic filler such as a silica filler to reduce the coefficient of linear expansion or to increase the package strength during heating. It is known that In particular, in the case of a package crack, the crack occurs when the moisture generated by the moisture absorption of the package itself rapidly evaporates in the package due to the heat treatment during mounting, and the stress generated exceeds the strength of the package itself. Therefore, increasing the content of the inorganic filler not only increases the heat strength of the package, but also helps prevent the package from cracking during mounting by reducing the absolute amount of moisture absorbed by the resin portion (tail shape). Masaji et al., "Low Thermal Expansion Epoxy Resin Molding Materials" The 38th Symposium on Thermosetting Resins, 123-126 (1988), Ishii Toshiaki et al., "Effect of Spherical Filler Particle Size on Flowability of Epoxy Molding Materials" Influence of distribution
3rd thermosetting resin lecture meeting, 141-144 (1993)).

However, when the content of the silica filler is increased with respect to the combination of an ortho-cresol novolak type epoxy resin and a phenol novolak curing agent which have been widely used for semiconductor encapsulation, the fluidity during molding is increased. Was extremely reduced, and in order to obtain a good package molded product, the filler content had to be suppressed to less than 85% by weight, and the package crack resistance at the time of mounting was insufficient.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies to solve the above problems.
It is an object of the present invention to provide a sealing resin composition which has high resistance to heat history during mounting without impairing moldability and provides a semiconductor device having excellent reliability.

[0006]

According to the present invention, there is provided (A) a compound represented by the following general formula:

[0007]

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An epoxy resin containing at least 50% by weight of a bifunctional epoxy resin represented by the following formula in an epoxy resin component:
(B) a phenolic curing agent containing a resin containing at least three phenolic hydroxyl groups in its skeleton as a main component, and (C) an inorganic filler as essential components. An epoxy resin composition for encapsulating a semiconductor, comprising an inorganic filler in a ratio of 85 to 97% by weight.

The epoxy resin represented by the general formula (1) is synthesized by reacting a bisphenol compound represented by the following general formula (2) with epichlorohydrin.

[0010]

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This reaction can be carried out by the same operation as the reaction for synthesizing a normal bisphenol A type epoxy resin. For example, after dissolving a bisphenol compound represented by the general formula (2) in epichlorohydrin in a molar ratio of about 10 times, 30 to 100% in the presence of sodium hydroxide.
C., preferably in the range of 50 to 80.degree. C. for 1 to 5 hours. The amount of sodium hydroxide used at this time is desirably approximately equimolar to 1 mol of the bisphenol compound. After completion of the reaction, excess epichlorohydrin is distilled off under reduced pressure, a solvent such as methyl isobutyl ketone is added and dissolved, and the resulting inorganic salt is removed by filtration and washing with water. Thereafter, the target epoxy resin can be obtained by removing the solvent again under reduced pressure.

The epoxy resin used in the present invention contains 50% by weight of the epoxy resin represented by the general formula (1).
It is desirable to contain the above. This is because the epoxy resin represented by the general formula (1) has a low viscosity, and can reduce the melt viscosity during molding when a phenolic curing agent and an inorganic filler are blended to form a molding material. It is preferable because the filling rate of the inorganic filler can be increased. If the epoxy resin of the general formula (1) is less than 50% by weight of the epoxy resin component, the effects of lowering the viscosity and increasing the filling cannot be obtained, which is not preferable.

An epoxy resin other than the general formula (1) can be used in an amount of less than 50% by weight of the epoxy resin component. To illustrate these, phenol, o-
A novolak epoxy resin obtained by epoxidizing a novolak compound which is a reaction product of phenols such as cresol and formaldehyde, tris- (4-hydroxyphenyl) -methane, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane Glycidyl ether compounds derived from trivalent or higher phenols such as, glycidyl ether compounds derived from halogenated bisphenols such as bisphenol A, bisphenol F, hydroquinone, dihydric phenols such as resorcinol, and tetrabromobisphenol A, Glycidyl ether compounds of polyhydric phenols obtained by condensation reaction between phenols and aromatic carbonyl compounds, p-aminophenol, m-aminophenol, 4-aminomethcresol, 6-aminomethcresol, 4,4′- Diaminodiph Phenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenylether, 1,4
-Bis (4-aminophenoxy) benzene, 1,4-bis (3-
Aminophenoxy) benzene, 2,2-bis (4-aminophenoxyphenyl) propane, p-phenylenediamine,
m-phenylenediamine, 2,4-toluenediamine, 2,
Amine-based epoxy resin derived from 6-toluenediamine, p-xylylenediamine, m-xylylenediamine, 1,4-cyclohexanebis (methylamine), 1,3-cyclohexanebis (methylamine), etc .; Glycidyl ester compounds derived from aromatic carboxylic acids such as oxybenzoic acid, m-oxybenzoic acid, terephthalic acid, and isophthalic acid; hydantoin-based epoxy compounds derived from 5,5-dimethylhydantoin; Screw (3,
4-epoxycyclohexyl) propane, 2,2-bis [4-
(2,3-epoxypropyl) cyclohexyl] propane,
There are alicyclic epoxy resins such as vinylcyclohexenedionoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, N, N-diglycidylaniline, etc., and one or two of these epoxy resins The above is used.

The curing agent used in the epoxy resin composition of the present invention is preferably a resin containing at least three phenolic hydroxyl groups in its skeleton as a main component.
When the number of phenolic hydroxyl groups is two or less, the bifunctional epoxy resin of the general formula (1) cannot be sufficiently crosslinked and cured, and as a result, heat resistance and physical properties are undesirably reduced. 50% by weight of a phenolic curing agent component containing at least three phenolic hydroxyl groups
Above values are preferred because sufficient crosslinking and curing reactions are possible, and a cured product having excellent heat resistance and physical properties is provided.

The structure of the phenolic curing agent is not particularly limited, but for example, tris- (4-
(Hydroxyphenyl) ethane, phenol novolak,
O-cresol novolak, naphthol novolak, trivalent or higher phenols represented by polyvinylphenol, etc., and further phenols, naphthols or bisphenol A, bisphenol F, bisphenol S,
4,4'-biphenol, hydroquinone, resorcinol,
Polyhydric phenolic compounds synthesized with a condensing agent such as formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde and p-xylylene glycol of dihydric phenols such as naphthalene diol.

The inorganic filler used in the present invention is desirably contained in a proportion of 85 to 97% by weight based on the whole resin composition. When the content is 85% by weight or more, the semiconductor itself obtained by curing from the epoxy resin composition decreases in water absorption and the strength of the package when heated is improved. Therefore, cracks are generated in the package due to heat history at the time of solder connection mounting. Can be prevented. On the other hand, if it exceeds 97% by weight, the melt viscosity during molding will increase,
It is not preferable because the fluidity is extremely reduced and a good molded product of the resin-encapsulated semiconductor cannot be obtained.

The inorganic filler of the present invention is not particularly limited, but usually spherical or crushed silica powder such as fused silica or crystalline silica, alumina powder, glass powder and the like can be used. It goes without saying that two or more fillers can be used in combination.

The epoxy resin composition for semiconductor encapsulation of the present invention contains a curing accelerator, a flame retardant, a filler, a coloring agent, a release agent and a surface treatment agent.

Examples of the curing accelerator include imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole; amines such as 2,4,6-tris (dimethylaminomethyl) phenol and benzyldimethylamine; Tributylphosphine, triphenylphosphine,
Organic phosphorus compounds such as tris (dimethoxyphenyl) phosphine, triphenylphosphine-triphenylboron, and tetraphenylphosphine-tetraphenylborate are exemplified. Two or more kinds may be used in combination.

As the flame retardant, any of known addition type and reaction type can be used. For example, brominated epoxy resin derived from tetrabromobisphenol A, red phosphorus, phosphate ester and the like can be used. Examples include phosphorus-based flame retardants, nitrogen-based flame retardants such as melamine, guanidine, and melamine cyanurate, and inorganic flame retardants such as aluminum hydroxide, magnesium hydroxide, antimony trioxide, and antimony pentoxide. If necessary, two or more kinds may be used in combination.

As the colorant, pigments, dyes and the like can be used, but usually carbon black and the like are preferably used.

Examples of the release agent include, but are not limited to, natural waxes, synthetic waxes, higher fatty acids or metal salts thereof, and paraffin.

The surface treating agent used in the present invention is a surface treating agent for a filler, and a known silane coupling agent, titanate-based or aluminum-based coupling agent, or the like can be used.

The epoxy resin composition for encapsulating a semiconductor of the present invention has the above-described constitution, so that even when the content of the inorganic filler is increased to 85% or more, excellent fluidity during molding is obtained. A good resin-sealed semiconductor can be obtained. Furthermore, the package of this semiconductor device has a low filler property and therefore has a lower hygroscopicity than conventional packages. A highly reliable semiconductor device can be provided without causing a package crack.

[0025]

Next, the present invention will be described in more detail by way of examples.

(Example 1) Epoxy resin (C-1) obtained by glycidyl etherification of 1,4-bis (p-hydroxyphenoxy) benzene (epoxy equivalent: 220 [g / e]
q]), terpene phenol resin YLH-402 (hydroxyl equivalent: 170 [g / eq]) manufactured by Yuka Shell Epoxy Co., Ltd., phenol novolak resin PR-517 manufactured by Sumitomo Durez Co., Ltd.
14 (hydroxyl equivalent: 103 [g / eq]), average particle size 11 μm
After mixing the spherical fused silica powder, the spherical fused silica powder having an average particle diameter of 30 μm, the crushed fused silica powder having an average particle diameter of 6 μm, a curing accelerator (triphenylphosphine), and other additives in the proportions shown in Table 1, After kneading at 90 ° C. for 8 minutes using a mixing roll, the mixture was pulverized by cooling to prepare a resin composition for encapsulating a semiconductor. This sealing resin composition is
Transfer molding under conditions of 5 ° C / 3 minutes, 175 ° C
For 6 hours to prepare a molded test piece.

The bending strength (JI) of the test piece thus obtained was
SK6911) was measured at 240 ° C. Also, TM
In A (thermomechanical test), the coefficient of linear expansion and the glass transition temperature were measured. Further, after molding 80 pin QFPIC, after post-curing, after performing a moisture absorption treatment for 24 hours, 72 hours, and 168 hours in an 85 ° C. and 85% constant temperature and humidity apparatus, the package is processed by an IR reflow device (240 ° C./10 seconds), and then packaged. Cracks were observed. Table 2 shows the results.

(Examples 2 to 4, Comparative Examples 1 to 6) After mixing the respective materials at the ratios shown in Table 1, various physical properties were measured in the same manner as in Example 1. Table 2 shows the measurement results.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

The epoxy resin composition for encapsulating a semiconductor obtained by the present invention has a low viscosity in a molten state.
The content of the inorganic filler can be increased, and the resulting semiconductor device has low thermal stress and high heat strength, and thus has excellent crack resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01L 23/31 (56) References JP-A-62-141223 (JP, A) JP-A-6-313025 (JP, A) JP-A-57-23625 (JP, A) JP-A-58-75854 (JP, A) JP-A-58-75857 (JP, A) JP-A-4-120126 (JP, A) JP-A-4-153213 ( JP, A) JP-A-4-183709 (JP, A) JP-A-5-5053 (JP, A) JP-A-4-183711 (JP, A) JP-A-6-107911 (JP, A) Hei 1-501800 (JP, A) Special table Hei 2 -502927 (JP, A) Special table Hei 2 -503009 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 59 / 24 C08G 59/62 C08L 63/00-63/02 H01L 23/29

Claims (3)

(57) [Claims] (A) General formula (1) An epoxy resin containing at least 50% by weight of a bifunctional epoxy resin represented by the following formula in the epoxy resin component: (B) a phenolic curing agent mainly containing a resin containing at least three phenolic hydroxyl groups in its skeleton; and An epoxy resin composition for semiconductor encapsulation, comprising (C) an inorganic filler as an essential component, and containing the inorganic filler (C) in a ratio of 85 to 97% by weight based on the entire resin composition. object. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein a resin containing at least three phenolic hydroxyl groups in the skeleton is at least 50% by weight of the phenolic curing agent component. 3. A curing accelerator, a flame retardant, a filler, a colorant,
The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, further comprising a release agent and a surface treatment agent.