Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2000-11-16
2002-03-19
Tucker, Philip (Department: 1712)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C257S789000, C257S791000, C257S792000, C257S793000, C523S435000, C523S443000
Reexamination Certificate
active
06358629
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an epoxy resin composition employed for encapsulation material of a semiconductor device and a semiconductor device using the same.
Recently as an encapsulation process for a semiconductor device, there has been mainly investigated an encapsulation process for a semiconductor by employing an epoxy resin composition, mainly comprising an epoxy resin, a curing agent and inorganic filler. Properties claimed for the encapsulation material have become severer year after year with increasing thermal resistance, reliability at a high temperature, reliability at high humidity and the like claimed for a semiconductor device. Among those, in order to improve crack resistance for moisture adsorption of the package, there has been developed and already employed practically encapsulation material comprising an epoxy resin having biphenyl structure having low moisture adsorption as an epoxy resin.
However, since the encapsulation material made from the epoxy resin having biphenyl structure generally has a glass transition temperature (Tg) of at most 130° C., there was a problem of low reliability such as high temperature storage.
And as usual in order to maintain safety of the encapsulation material, the material contained a halogenated flame retardant such as a brominated epoxy resin as a flame retardant and an antimony compound such as antimony trioxide. But recently the environmental problems have become highly important, these compounds have been regarded as questionable even in ISO 14000. Therefore, a new flame retardant has been attempted to employ with environmental consideration. For example, there have been proposed an epoxy resin composition excellent in flame retardancy and reliability at a high temperature, which contains a phosphate compound, a red phosphorus flame retardant or the like without the halogenated flame retardant and the antimony compound as the conventional flame retardant. However, in case of employing the phosphate compound, there arises a problem of lowering reliability at high humidity due to apprehension of acid corrosion.
SUMMARY OF THE INVENTION
The present invention was made to solve the above mentioned problems. And the object of the present invention is to improve high temperature storage of an epoxy resin composition comprising an epoxy resin having biphenyl structure, and to provide a resin composition having high flame retardancy without a halogenated flame retardant and an antimony compound as a conventional flame retardant. Furthermore, the object is to provide a semiconductor device having high reliability obtained by employing the above mentioned epoxy resin composition as encapsulation material.
Namely, the present invention relates to an epoxy resin composition for semiconductor encapsulation comprising an epoxy resin, a curing agent, inorganic filler, a catalyst, a flame retardant, and an additive, wherein the composition is obtained by employing the epoxy resin mainly containing an epoxy resin having biphenyl structure, the phenolic resin mainly containing a zylok type phenolic resin (namely a phenolic aralkyl resin), a polysiloxane compound modified with polyether containing an amino group as the flame retardant, a polyimide resin as the additive, and not less than 87% by weight (usually 87 to 92% by weight) of the inorganic filler based on the total-composition.
And an amount of the polyimide resin as an additive is preferably 0.5 to 30 parts by weight based on total 100 parts by weight of the epoxy resin and the curing agent.
The polyimide resin as an additive is preferably the resin having both end groups thereof modified with an epoxy resin or a phenolic resin.
Further, the inorganic filler is preferably silica particle powder such as fused silica having a maximum particle diameter of not more than 75 &mgr;m (an average particle diameter is usually 0.1 to 50 &mgr;m).
The catalyst is preferably a phosphorus catalyst or a latent phosphorus catalyst.
A semiconductor device of the present invention is encapsulated by one of the above-mentioned epoxy resin compositions, wherein a semiconductor element is mounted on an iron frame, and loop length of a wire bond is not more than 3 mm.
And a semiconductor device of the present invention is encapsulated by one of the above-mentioned epoxy resin compositions, wherein a semiconductor element is mounted on a copper frame, and loop length of a wire bond is not less than 3 mm.
DETAILED DESCRIPTION
EMBODIMENT 1
Table 1 shows composition of the epoxy resin composition in embodiment 1 of the present invention. The epoxy resin composition of the present embodiment comprises an epoxy resin, a curing agent, an inorganic filler, a catalyst, a flame retardant and an additive which is employed for semiconductor encapsulation material. The embodiment 1 of the present invention is explained below based on Table 1. “Parts” or “%” in Detailed Description respectively means “parts by weight” or “%” by weighty, unless otherwise specified.
TABLE 1
Compositions of the epoxy resin composition
name
content
amount, other
epoxy resin
main-
epoxy resin having biphenyl structure,
0 to 30 parts of epoxy resin having terpene structure,
sub-
epoxy resin having terpene structure,
cresol novolak epoxy resin, or epoxy resin having
cresol novolak epoxy resin,
naphthalene structure based on 100 parts of epoxy resin
or epoxy resin having naphthalene structure
having biphenyl structure as a main component
curing agent
main-
phenolic aralkyl resin,
0 to 30 parts of phenolic resin having terpene structure,
sub-
phenolic resin having terpene structure,
a phenolic novolak resin or phenolic resin having
phenolic novolak resin,
naphthalene structure based on 100 parts of phenolic
or phenolic resin having naphthalene structure
aralkyl resin as a main component
0.5 to 1.5 moles of a phenolic hydroxy group based on
1 mole of an epoxy group
additive
a polyimide resin
0.5 to 30 parts based on 100 parts of an epoxy resin and
a curing agent
inorganic filler
fused silica
not less than 87% in the total composition
not more than 75 &mgr;m of maximum particle diameter
catalyst
a phosphorus catalyst, or
0.5 to 5 parts based on 100 parts of an epoxy resin and
a latent phosphorus catalyst
a curing agent
flame retardant
a polysiloxane compound modified with
0.2 to 5 parts based on 100 partrs of an epoxy resin and
polyether containing an amino group
a curing agent
coupling agent
epoxy silane or amino silane
depending on an amount of an inorganic filler
mold releasing
a natural carnauba wax or
1 to 10% in the total composition
agent
a natural/synthetic ester wax
pigment
carbon black
0.5 to 10% in the total composition
The epoxy resin composition of the present embodiment is obtained by mainly employing an epoxy resin having biphenyl structure as an epoxy resin. But the epoxy resin having biphenyl structure as a main component may be mixed with an epoxy resin having terpene structure, a cresol novolak epoxy resin or an epoxy resin having naphthalene structure. In this case, 100 parts by weight of the epoxy resin having biphenyl structure as a main component can be mixed with 0 to 30 parts by weight of an epoxy resin having terpene structure, a cresol novolak epoxy resin or an epoxy resin having naphthalene structure.
As a curing agent, a phenolic aralkyl resin is mainly employed. But the phenolic aralkyl resin as a main component may be mixed with a phenolic resin having terpene structure, a phenolic novolak resin or a phenolic resin having naphthalene structure. In this case, 100 parts by weight of the phenolic aralkyl resin as a main component can be mixed with 0 to 30 parts by weight of a phenolic resin having terpene structure, a phenolic novolak resin or a phenolic resin having naphthalene structure. Mixing ratio of an epoxy resin and a curing agent is preferably 0.5 to 1.5 mole of a phenolic hydroxy group of the curing agent based on 1 mole of an epoxy group of the epoxy resin.
The chemical structures of these epoxy resins and these curing agents are respectively shown in the following Table
Aylward D.
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
Tucker Philip
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