Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
2000-11-27
2003-11-11
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C428S417000, C428S418000, C428S901000, C523S200000, C524S401000
Reexamination Certificate
active
06645630
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an epoxy resin composition for a prepreg used for manufacturing a printed-wiring board or a multilayer printed-wiring board, a prepreg, and a multilayer printed-wiring board.
2. Description of the Background Art
A nonflammable epoxy resin is used in a variety of electrical insulating materials due to the excellent self-extinguishing property, mechanical property, water-vapor resistance and electrical property.
The previous nonflammable epoxy resins contain a halogen system compound including mainly bromine in order to impart nonflammability and this affords the self-extinguishing property to molded particles. However, when such the molded articles burn upon firing or the like, there is a possibility that compounds harmful to the human body such as polybrominated dibenzodioxin, furan and the like are formed. Moreover, when compounds containing bromine are heated, bromine is released by decomposition and, thus, the heat resistance in long term is deteriorated. For that reason, there is desired development of molded articles having the excellent nonflammability and heat resistance without adding a halogen system compound.
As a strategy to this problem, flame-retardation using mainly a phosphorus element is being studied. For example, by incorporating an addition-type phosphorus system flame-retardant such as triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyldiphenyl phosphate (CDP) and the like which are a phosphate system compound into an epoxy resin composition, the nonflammability can be maintained. However, since general phosphorus compounds described above do not react with an epoxy resin, other problems arise that the solder heat resistance after moisture absorption and the resistance to chemicals such as the alkali resistance and the like of molded articles are significantly reduced.
Then, as disclosed in JP-A 4-11662, JP-A 11-166035 and JP-A 11-124489, the use of phosphorus compounds having the reactivity with an epoxy resin is proposed. However, even when these phosphorus compounds are used, the properties such as the solder heat resistance after moisture absorption and the like are not sufficient as compared with previous nonflammable epoxy resins using a halogen system compound. In addition, even when widely used general resins such as bisphenol A-type epoxy resin are used, a glass transition temperature (hereinafter, referred to as Tg) of a molded article is lowered and, furthermore, in the case of a printed-wiring board and a multilayer printed-wiring board using this molded article, the adhering force between layers of a laminated sheet or to a copper foil of an inner layer substrate is reduced.
One reason why more excellent solder heat resistance over the previous one is required in addition to nonflammability is a problem of today's earth environment. That is, release of lead used in a solder material into the natural environment has become a serious problem and, as one strategy thereto, the use of a lead-free solder has been initiated. Pursuant to this, a solder treating temperature is elevated higher by about 10 to 15° C. than the previous temperature and, thus, there arises a difficulty that the aforementioned techniques can not deal therewith.
The present invention was done in view of the above problems and an object thereof is to provide an epoxy resin composition for a prepreg used in manufacturing a printed-wiring board and a multilayer printed-wiring board which do not produce harmful substances upon burning, are excellent in the nonflammability, the solder heat resistance after moisture absorption and the adherability and has a high Tg at molding, a prepreg and a multilayer printed-wiring board.
SUMMARY OF THE INVENTION
An epoxy resin composition relating to the present invention is an epoxy resin composition comprising, as an essential component, a phosphorus compound having an average of not less than 1.8 and less than 3 of phenolic hydroxy groups reactive with an epoxy resin and an average of not less than 0.8 of a phosphorus element in the molecule, an inorganic filler having an average particle diameter of not greater than 30 &mgr;m, a bifunctional epoxy resin having an average of not less than 1.8 and less than 2.6 of epoxy groups in the molecule and a hardener, wherein the bifunctional epoxy resin is contained at an amount of not less than 51% by mass relative to the whole epoxy resin, dicyandiamide is used as the hardener and a ratio (a/c) of equivalent (a) of a phenolic hydroxy group of the phosphorus compound and equivalent (c) of an epoxy group of the bifunctional epoxy resin is not less than 0.3 and less than 0.75, and an epoxy resin composition relating to the present invention is an epoxy resin composition comprising, as an essential component in the molecule, a phosphorus compound having an average of not less than 1.8 and not less 3 of phenolic hydroxy groups reactive with an epoxy resin and an average of not less than 0.8 of a phosphorus element, an inorganic filler having an average particle diameter of not greater than 30 &mgr;m, a bifunctional epoxy resin having an average of not less than 1.8 and less than 2.6 of epoxy groups in the molecule and a hardener, wherein the bifunctional epoxy resin is contained at an amount of not less than 51% by mass relative to the whole epoxy resin, a polyfunctional phenol system compound having an average of not less than 3 phenolic hydroxy groups in the molecule is used as the hardener and a ratio (a/c) of equivalent (a) of a phenolic hydroxy group of the phosphorus compound and equivalent (c) of an epoxy group of the bifunctional epoxy resin is not less than 0.3 and less than 0.75.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be explained below.
A phosphorus compound in the present invention is not particularly limited as long as it has an average of not less than 1.8 and less than 3 of phenolic hydroxy groups reactive with an epoxy resin and an average of not less than 0.8 of a phosphorus element in the molecule. When such the phosphorus compound having a bifunctional phenolic hydroxy group and a bifunctional epoxy resin described below are reacted, a linear polymer compound can be obtained. And, when this compound is cured with a hardener described below, a molded article having the excellent toughness, flexibility, adherability and stress relaxation upon heating can be obtained. Here, when the number of phenolic hydroxy groups is an average of less than 1.8, it becomes difficult to react with a bifunctional epoxy resin to produce the aforementioned linear polymer compound. On the other hand, when the number of phenolic hydroxy groups is an average of not less than 3, a product by a reaction with a bifunctional epoxy resin is gelatinized and, thus, it becomes difficult to stably manufacture an epoxy resin composition. In addition, when the number of a phosphorus element is less than 0.8, it becomes difficult to impart the sufficient nonflammability.
As an example of a phosphorus compound, phosphorus compounds having a bifunctional phenolic hydroxy group represented by the formula (1) to (3) are preferable and these are particularly excellent in the nonflammability, the heat resistance and the like.
Here, a ratio (a/c) of equivalent (a) of a phenolic hydroxy group of a phosphorus compound and equivalent (c) of an epoxy group of a bifunctional epoxy resin is set at not less than 0.3 and less than 0.75. By setting like this, the aforementioned linear polymer compound can be sufficiently produced and, as a result, a molded article having the excellent toughness, flexibility, adherability and stress relaxation upon heating can be obtained. To the contrary, when this ratio is less than 0.3, such properties can not be obtained. When the ratio is not less than 0.75, Tg tends to be lowered.
Furthermore, it is preferable to set the content of a phosphorus element component at not less than 0.8% by mass and less than 3.5% by mass of the whole resin solids constituent in an
Asano Takuya
Ito Naoki
Nakamura Yoshihiko
Ogasawara Kenji
Dawson Robert
Keehan Christopher M
Matsushita Electric & Works Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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