Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-01-30
2003-12-09
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C528S098000, C549S543000
Reexamination Certificate
active
06660811
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an epoxy resin composition which is excellent in flame retardance and which is suitably used as a semiconductor-sealing material or a printed circuit board material.
BACKGROUND OF THE INVENTION
An epoxy resin can be cured with various curing agents to form a cured product normally excellent in mechanical properties, humidity resistance, chemical resistance, heat resistance, electrical properties, etc. Thus, an epoxy resin finds wide application to electronic materials and molding materials. An epoxy resin to be used in the art of electronic materials such as printed wiring circuit board essentially comprises a halogen compound incorporated therein to render these materials flame retardant. In recent years, however, a halogen-based flame retardant has been considered problematic as a dioxin-producing factor from the standpoint of environmental protection. Thus, it has been keenly desired to provide a halogen-free flame retardant epoxy resin material. In the art of semiconductor-sealing material, as the semiconductor surface packaging process has spread, the solder crack resistance of the semiconductor package has become an important factor. A conventional semiconductor-sealing material comprising a cresol-novolac type epoxy resin and a phenol-novolac resin in combination exhibits an excellent heat resistance but is disadvantageous in that it exhibits a poor humidity resistance and hence a deteriorated solder crack resistance.
Referring to the method for solving these problems, Japanese Patent Laid-Open No. 2000-1524 discloses a technique involving the use of an epoxy resin having a specific molecular structure that meets the requirements for humidity resistance. The invention of the above cited Japanese Patent Laid-Open No. 2000-1524 can provide a cured product excellent in humidity resistance but is poor in flame retardance, which is required in the art of electronic material. Further, the epoxy resin described in Japanese Patent Laid-Open No. 2000-1524 is bifunctional and thus cannot increase in its crosslinking density. Thus, the foregoing epoxy resin exhibits a deteriorated heat resistance and leaves something to be desired in the improvement of solder crack resistance.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a flame retardant epoxy resin material which is excellent in flame retardance as well as in heat resistance despite halogen-free composition.
Other objects and effects of the present invention will become apparent from the following description.
Under these circumstances, the inventors made extensive studies seeking epoxy resin compositions which give cured products excellent in flame retardance as well as in heat resistance. As a result, it was found that the foregoing requirements can be satisfied by an epoxy resin composition comprising: a novel epoxy resin having two or more repeating units each comprising a methylene bond substituted by at least an aromatic ring and a benzene ring substituted by at least a glycidyloxy group, the aromatic ring being at least one member selected from the group consisting of (a) condensed aromatic rings and (b) combinations of aromatic rings in which two or more aromatic monocycles or condensed aromatic rings are connected directly to each other via a single bond; and a curing agent. The invention has thus been worked out.
The invention has been worked out on the basis of the foregoing technical knowledge. That is, the invention provides an epoxy resin composition comprising:
(i) an epoxy resin having a melt viscosity of from 0.1 dPa to 5 dPa at 150° C. and having two or more repeating units each comprising:
a methylene bond substituted by at least an aromatic ring; and
a benzene ring substituted by at least a glycidyloxy group,
wherein the aromatic ring is at least one member selected from the group consisting of (a) condensed aromatic rings and (b) combinations of aromatic rings in which two or more aromatic monocycles or condensed aromatic rings are connected directly to each other via a single bond; and
(ii) a curing agent.
DETAILED DESCRIPTION OF THE INVENTION
The epoxy resin to be incorporated in the epoxy resin composition according to the invention has a melt viscosity of from 0.1 dPa to 5 dPa at 150° C. and has two or more repeating units each comprising a methylene bond substituted by at least an aromatic ring and a benzene ring substituted by at least a glycidyloxy group, wherein the aromatic ring is at least one member selected from the group consisting of (a) condensed aromatic rings and (b) combinations of aromatic rings in which two or more aromatic monocycles or condensed aromatic rings are connected directly to each other via a single bond.
Examples of the condensed aromatic ring (a) include condensed rings such as naphthalene, fluorene, acenaphthacene, indene, anthracene, pyrene, chrysene and triphenylene.
Examples of the combinations of aromatic rings (b), in which two or more aromatic monocycles or condensed aromatic rings are connected directly to each other via a single bond, include structures having aromatic monocycles connected directly to each other via a single bond, such as biphenyl and p-terphenyl; structures comprising an aromatic hyrocarbon having two or more independent benzene rings, such as phenyl methyl phenyl, phenoxyphenyl, bibenzylyl and stilbenyl; and structures in which functional groups having hydrocarbon skeletons of condensed rings, such as indenyl, naphthyl, anthryl and phenanthryl, are connected to each other.
Preferred among the above-exemplified aromatic rings are biphenyl group, p-terphenyl group, phenoxyphenyl group, bibenzylyl group, indenyl group, naphthyl group, anthryl group, and phenanthryl group. Furthermore, functional groups having a hydrocarbon skeleton having a condensed ring such as biphenyl group, p-terphenyl group, phenoxyphenyl group, indenyl group, naphthyl group, anthryl group and phenanthryl group are preferred because they provide a resin excellent in flame retardance. Biphenyl group and naphthyl group are particularly preferred.
To the foregoing benzene ring that is substituted by at least a glycidyloxy group may be connected a group other than glycidyloxy group, such as C
1
-C
6
alkyl group, C
5
-C
6
cycloalkyl group, C
1
-C
6
alkoxyl group, C
5
-C
6
cycloalkoxyl, phenyl, phenoxy or glycidyloxyphenyl group as a substituent.
Examples of the epoxy resin include those having a structure represented by the following general formula (1):
wherein R
1
to R
3
may be the same or different and each represent a hydrogen atom, a C
1
-C
6
alkyl group, a C
5
-C
6
cycloalkyl group, a C
1
-C
6
alkoxyl group, a C
5
-C
6
cycloalkoxyl group, a phenyl group, a phenoxy group or a glycidyloxyphenyl group; Ar represents a hydrocarbon group having a member selected from the group consisting of C
6
-C
18
condensed aromatic rings, combinations of two or more C
6
-C
18
aromatic monocycles connected directly to each other via a single bond, and combinations of two or more C
6
-C
18
condensed aromatic rings connected directly to each other via a single bond; n represents the number of repeating units ranging from 2 to 15; and G represents a glycidyl group.
Of these, epoxy resins having a structure represented by the following general formula (2) are particularly preferred:
wherein R
1
represents a hydrogen atom, a C
1
-C
6
alkyl group, a C
5
-C
6
cycloalkyl group, a C
1
-C
6
alkoxyl group, a C
5
-C
6
cycloalkoxyl group, a phenyl group, a phenoxy group or a glycidyloxyphenyl group; Ar represents a hydrocarbon group having a member selected from the group consisting of C
6
-C
18
condensed aromatic rings, combinations of two or more C
6
-C
18
aromatic monocycles connected directly to each other via a single bond, and combinations of two or more C
6
-C
18
condensed aromatic rings connected directly to each other via a single bond; n represents the number of repeating units ranging from 2 to 15; and G represents a glycidyl group.
Preferred examples of the epoxy resin having a struct
Ogura Ichiro
Takahashi Yoshiyuki
Armstrong Kratz Quintos Hanson & Brooks, LLP
Aylward D.
Dainippon Ink and Chemicals Inc.
Dawson Robert
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