Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Noninterengaged fiber-containing paper-free web or sheet...
Reexamination Certificate
1999-01-06
2001-05-15
Sellers, Robert E. L. (Department: 1712)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Noninterengaged fiber-containing paper-free web or sheet...
C428S413000, C525S486000, C525S504000
Reexamination Certificate
active
06231959
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an epoxy resin composition employed in, for example, manufacturing a laminated sheet used as a material for a printed wiring board.
DESCRIPTION OF RELATED ART
The laminated sheet used as the material for the printed wiring board has been manufactured by laminating prepregs of such substrate as a glass cloth or the like impregnated with a varnish consisting of an epoxy resin composition and dried, disposing copper foils on the top and bottom of the laminated prepregs, and molding them integral. In such epoxy resin composition for the purpose of making the prepreg and the laminated sheet as well, it has been general that such compound of amines as dicyandiamide is used as a hardening agent. In recent years, on the other hand, continued increments in mounting density of circuit elements are demanding a provision of a laminated sheet more excellent in the heat resistance than known laminated sheets, and a use of a phenolic hardening agent excellent in the heat resistance and effective in shortening required molding time and so on has been investigated. The present inventors have also investigated the epoxy resin compositions for use in making the laminated sheet with the phenolic hardening agent employed, and have discovered that, as has been disclosed in Japanese Patent Application No. 6-29982, a use of imidazoles, tertiary amines or the like as a hardening promotion agent causes a problem to arise in respect of the preservation stability of the prepreg, whereas a use of organic phosphine-containing compound, in particular, such organic phosphine.organic boron complex as tetraphenylphosphonium.tetraphenylborate as the hardening promotion agent improves remarkably the preservation stability of the prepreg.
However, the organic phosphine organic boron complex such as tetraphenylphosphonium.tetraphenylborate is generally incompatible or compatible (soluble) just in trace amount with the epoxy resin and solvents at normal temperatures, and varnishes (epoxy resin compositions) with these hardening promotion agents blended therein have been in opaque state in which the hardening promotion agent is dispersed. Due to this, there has been a problem that the varnish preserved for many hours (for about a week) is caused to become non-homogeneous by the precipitation of dispersed hardening promotion agent so as to render the prepreg to fluctuate in expected properties. In the multilayered printed circuit board, on the other hand, it is required to secure a sufficient adhesion between printed copper circuit formed in inner layered circuit board and a resin forming prepregs. The inner layered circuit board is usually prepared by forming a circuit pattern in electrolytic copper foil bonded on a surface of copper-clad laminate. Usual electrolytic copper foil is provided to be roughened on one surface, referred to as a matte surface, and smoothed on the other surface, referred to as a shiny surface, and the copper foil is bonded at the roughened matte surface onto a laminate in forming the copper clad laminate, so that the top surface of the printed copper circuit formed on the inner layered circuit board will be the smooth shiny surface and the adhesion between the copper circuit and the prepreg resin will tend to be lowered. For this reason, it has been demanded to elevate the adhesion between the copper circuit and the prepreg resin.
Accordingly, it has been attempted in various manners to elevate the adhesion between the copper circuit and the prepreg resin such that, for example, a copper oxide is formed on the surface of the copper circuit to elevate the adhesion, whereby the copper circuit is provided with fine projections inherent to the surface of the copper oxide obtained through an oxidizing treatment of copper, and the copper circuit surface is roughened by such-fine projections to be able to elevate the adhesion. For a measure of forming the copper oxide on the surface of the copper circuit, one referred to as a blackening treatment employing an alkaline aqueous solution containing sodium chlorite has been generally employed.
While the adhesion between the copper circuit and the prepreg resin may be elevated by forming the copper oxide on the surface of the copper circuit, there has arisen such drawback as in the following. That is, as the copper oxide, in particular, cupric oxide is readily soluble in acid, an immersion in a bath of chemical or electrolytic plating solution of the multilayered substrate provided with through-holes for performing a through-hole plating causes cut and exposed copper oxide layers on inner walls of the through-holes of the copper circuit to melt in such acid as hydrochloric acid, so that such solvency erosion as a halo phenomenon will be readily caused to occur due to infiltration of the plating solution along boundaries between the copper circuit and the prepreg resin in the inner walls of the through-holes, and the reliability of the multilayered printed wiring board may have to be lowered.
A prior art related to the present invention is Japanese Patent Laid-Open Publication No. 5-163373 and, as reference art, U.S. Pat. Nos. 4,953,603, 4,559,395, 4,604,317 and 5,262,491 are enumerated.
SUMMARY OF THE INVENTION
The present invention has been suggested in view of the foregoing state of art, and its object is to provide an epoxy resin composition containing a phenolic hardening agent, which composition can manufacture a prepreg excellent in the preservation stability, and prevent the hardening promotion agent from precipitating even after the preservation for many hours in the form of varnish. It is a further object to obtain an epoxy resin composition which allowing the prepreg less causing the solvency erosion (halo phenomenon) due to the infiltration of the plating solution along the boundaries between the copper circuit formed in the inner layered circuit board and the prepreg resin to be obtainable.
According to the present invention, the above objects can be realized by means of an epoxy resin prepreg for use in printed wiring board, the prepreg comprising a substrate, and an epoxy resin composition, the composition comprising (a) an epoxy resin, (b) a hardening agent, (c) a hardening promotion agent, and (d) a solvent for dissolving the hardening promotion agent; wherein the hardening agent of (b) of 100 parts by weight contains 95 to 100 parts by weight of multifunctional phenols having more than two phenolic hydroxyl groups in each molecule; and the hardening promotion agent of (c) is a compound represented by the following general formula (1):
in which “n” denotes an integer of 1-4 and R denotes a monohydric organic group; the substrate being impregnated with the composition, thereafter heated and dried.
Further objects and advantages of the present invention shall be clarified as the description of the invention advances in the followings with reference to preferred embodiments.
While the present invention shall now be detailed with reference to specific embodiments, it should be appreciated that the intention is not to limit the invention only to the embodiments but rather to include all alterations, modifications and equivalent arrangements possible within the scope of appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The epoxy resin employed in the present invention may be any compound having more than two epoxy groups in each molecule, and may even be a mixture. As typical ones of such resin, bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, cresol novolak type epoxy resin, trifunctional type epoxy resin and the like can be employed, but the use is not limited only to them.
For the phenolic hardening agent employed in the present invention, any compound having more than two phenolic hydroxyl groups in each molecule or even a mixture of such compounds may be used. Typical phenolic hardening agent will be phenol novolak, cresol novolak and the like, but the use may not be limited thereto.
The hardening promotion agent e
Hatta Yukio
Iwamoto Narimasa
Matsumura Masahiro
Motobe Hidetsugu
Nakamura Yoshihiko
Burns Doane Swecker & Mathis L.L.P.
Matsushita Electric & Works Ltd.
Sellers Robert E. L.
LandOfFree
Prepreg of epoxy resin, hardener, and organodialkyurea promotor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Prepreg of epoxy resin, hardener, and organodialkyurea promotor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Prepreg of epoxy resin, hardener, and organodialkyurea promotor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2541087