Thermosetting resin compositions for build-up method

Details Thermosetting resin compositions for build-up method Thermosetting resin compositions for build-up method

1999-10-06

2001-10-23

Dawson, Robert (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C525S523000, C525S537000

Reexamination Certificate

active

06306935

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to thermosetting resin compositions for build-up method. More precisely, it relates to thermosetting resin compositions for build-up method comprising an epoxy resin, a curing agent for epoxy resin, and poly(ether sulfone). In addition, it relates to insulating materials for build-up method and build-up print circuit board using said thermosetting resin composition.
2. Description of the Related Art
In recent years, a high-density mounting has been demanded as the progress of downsizing, light weighing and thin shaping of electronic apparatuses. By this reason, it has become required in print circuit board not only to minimize circuit patterns but also to reduce diameter of through holes and via holes, and to adopt blind via holes. Increasing attention has been given to build-up print circuit boards obtainable by the build-up method as a product meeting with these requirements. Practical insulating materials for build-up circuit board include a photo-sensitive resin type having merit that a number of via holes, can be formed in one operation by exposure-development step and a thermosetting resin type which allows formation of finer via holes, by using the laser process. In case of photo-sensitive resin type insulating material, there is a limitation in selection of the photo-sensitive resin which gives a photosensitivity to the resin composition thereof, and there are many know-hows in the exposure-development step. Thus, at present, the thermosetting resin type insulating material is attracting more attention.
Proposed thermosetting resin compositions for use in the thermosetting resin type insulating materials include, in addition to a composition comprising a thermosetting resin alone such as an epoxy resin, a phenoxy resin or the like, a composition comprising a thermosetting resin and a thermoplastic resin. For example, JP-A-7-33991 and JP-A-7-34048 describe a thermosetting resin containing an epoxy resin and a poly(ether sulfone).
When the conventional thermosetting resin composition is used, however, it has been difficult to obtain an insulating material for build-up method which is satisfactory in low-thermal expansion and low-water absorption.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a thermosetting resin composition for build-up method which does not deteriorate the processability such as that found in the conventional one and which gives a cured product excellent in low-thermal expansion and low-water absorption, to provide an insulating material for build-up method using said thermosetting resin composition and to provide a build-up print circuit board using said insulating material.
Thus, the present invention provides (I) a thermosetting resin composition for build-up method comprising (A) an epoxy resin having two or more glycidyl groups, (B) a curing agent for epoxy resin, (C) a poly(ether sulfone) and (D) an inorganic filler.
In addition, the present invention provides (II) a thermosetting resin composition for build-up method comprising (A) an epoxy resin having two or more glycidyl groups, (B) a polyhydric phenol type curing agent for epoxy resin and (C) a poly(ether sulfone).
Further, the present invention provides (III) an insulating material for build-up method having a resin-containing layer formed by curing the thermosetting resin composition described for above (I) or (II).
The present invention also provides (IV) a build-up print circuit board formed by using the insulating material described for above (III).
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, known compounds can be used as the epoxy resin having two or more glycidyl groups as the component (A). Examples include di-functional epoxy resins derived from dihydric phenols such as bisphenol A, bisphenol F, tetrabromobisphenol A, bisphenol S, dihydroxybiphenyl, dihydroxynaphthalene, dihydroxystilbene, alkyl-substituted hydroquinone and the like; novolac type epoxy resin derived from novolacs such as phenol novolac, cresol novolac, naphtol novolac, bisphenol A novolac and the like; polyfunctional epoxy resins derived from polycondensation products of phenol compounds such as phenol, alkyl-substituted phenol, naphthol and the like with aldehydes such as benzaldehyde, terephthalaldehyde, alkyl-substituted terephthalaldehyde and the like; epoxy resins derived from polycondensation products of phenol compounds with cyclopentadiene; and so on. One or more of them can be used.
From the viewpoint of reactivity and compatibility with poly(ether sulfone), preferred are epoxy resins derived from bisphenol A, epoxy resins derived from bisphenol F, epoxy resins derived from phenol novolac and epoxy resins derived from cresol novolac. More preferred is an epoxy resins derived from cresol novolac.
On the other hand, from the viewpoint of a balance among reactivity, water absorption of cured products, heat resistance and so on, preferred are epoxy resins derived from phenol novolac, and epoxy resins derived from cresol novolac. The amount of the component (A) can be suitably selected in conjunction with other components and usually 1% by weight or more, preferably 1 to 80% by weight, based on the total amount of the thermosetting resin composition of the invention.
Process for producing the component (A) can be adopted amon g known processes including, for example, a process in which a phenol compound or its derivative is reacted with an epihalohydrin in the presence of an alkali such as sodium hydroxide.
In the present invention, known compounds can be used as the curing agent for epoxy resin as the component (B). Examples include polyhydric phenol curing agents for epoxy resin such as phenol novolac, cresol novolac, phenol-modified polybutadiene and the like; amine curing agents for epoxy resin such as dicyandiamide, diaminodiphenyl methane, diaminodiphenyl sulfone and the like; acid-anhydride curing agents for epoxy resin such as pyromellitic acid anhydride, trimellitic acid anhydride, benzophenone tetracarboxylic acid dianhydride and the like; and so on. One or more of them can be used. Among them, polyhydric phenol curing agents for epoxy resin such as phenol novolac are preferred from the viewpoint of low water absorption of cured product. The polyhydric phenol curing agents can be used for a thermosetting resin composition for build-up method even in the absence of an inorganic filler.
The amount of the component (B) may usually be determined so that the cured product obtained from the thermosetting resin composition of the invention has a high glass transition point. For example, a phenol novolac is used as the component (B), the ratio of the epoxy equivalent of the component (A) and the hydroxyl group equivalent of the component (B) is usually 1:0.8 to 1:1.2, and preferably 1:1.
In the present invention, known compounds can be used as the poly(ether sulfone) as the component (C). A terminal group of the poly(ether sulfone) molecule includes, for example, a halogen atom, an alkoxy group, a phenolic hydroxyl group and the like. From the viewpoint of solvent resistance and toughness of cured products, a phenolic hydroxyl group is preferred. In this case, it is preferred that the both terminals are phenolic hydroxyl groups. In the poly(ether sulfone) molecule, structural units other than the terminal(s) are not particularly limited.
The amount of the component (C) is usually 1 to 70% by weight based on the total amount of the thermosetting resin composition of the invention. When the amount is less than 10% by weight, the toughness of cured products may decrease. When the amount exceeds 70% by weight, processability of the composition may lower or the water absorption of cured products may increase.
Known process can be adopted as the processes for producing the component (C). In addition, Examples of commercially available products include Sumika Excel (trademark), manufactured by Sumitomo Chemical Co., Ltd. and REDEL (trademark), manufactured by Amoco Chemicals

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