Abstract: An epoxy resin composition for use in producing a prepreg for printed wiring boards excellent in appearance, flame retardancy, etc., which comprises an epoxy resin, a phenolic novolak, and a curing accelerator. It is characterized in that the epoxy resin comprises an epoxy (a) and an epoxy (b), wherein the epoxy (a) is a brominated epoxy resin which is obtained by reacting/mixing a bisphenol A epoxy resin with tetrabromobisphenol A and has an epoxy equivalent of 350 to 470 g/eq and an n=0 component content of 20 to 35% in terms of areal percentage in a GPC chart, and the epoxy (b) is at least one bifunctional epoxy resin which is obtained by reacting any one selected from the group consisting of bisphenol A, bisphenol F, and tetrabromobisphenol A with epichlorohydrin and has an n=0 component content as determined from a GPC chart of 60% or higher.

Abstract: An epoxy resin composition for printed wiring boards which comprises an epoxy resin, a phenolic novolak, a curing accelerator, and a silica filler, characterized in that the silica filler has a shape having at least two planes and has an average particle diameter of 0.3 to 10 ?m and a specific surface area of 8 to 30 m2/g. The epoxy resin composition has a higher apparent viscosity than the resins and can hence be inhibited from sagging in a drying oven. This composition retains the intact property of infiltration into reinforcements because the viscosity of the resins themselves has not increased locally. The composition hence produces the effect of improving the appearance of a prepreg.

Abstract: A prepreg for a printed wiring board characterized with use of a brominated epoxy resin, possessing a peak intensity of infrared absorption spectrum at 2100 to 2300 cm?1, which is 5% or lower than that of a benzene ring carbon-carbon double bond at 1600 cm?1 as measured with an infrared absorption spectrometer as well as having an inflection point between 120 and 150° C. in the cured product of said brominated epoxy resin as measured by means of a differential scanning calorimeter. The prepreg for the printed wiring board is superior in hygroscopicity, heat resistance, and desmear capability as a printed wiring board material and can be used to manufacture a copper-clad laminate board.

Abstract: An epoxy resin composition for printed wiring boards which comprises an epoxy resin, a phenolic novolak, a curing accelerator, and a silica filler, characterized in that the silica filler has a shape having at least two planes and has an average particle diameter of 0.3 to 10 ?m and a specific surface area of 8 to 30 m2/g. The epoxy resin composition has a higher apparent viscosity than the resins and can hence be inhibited from sagging in a drying oven. This composition retains the intact property of infiltration into reinforcements because the viscosity of the resins themselves has not increased locally. The composition hence produces the effect of improving the appearance of a prepreg.

Abstract: An epoxy resin composition for use in producing a prepreg for printed wiring boards excellent in appearance, flame retardancy, etc., which comprises an epoxy resin, a phenolic novolak, and a curing accelerator. It is characterized in that the epoxy resin comprises an epoxy (a) and an epoxy (b), wherein the epoxy (a) is a brominated epoxy resin which is obtained by reacting/mixing a bisphenol A epoxy resin with tetrabromobisphenol A and has an epoxy equivalent of 350 to 470 g/eq and an n=0 component content of 20 to 35% in terms of areal percentage in a GPC chart, and the epoxy (b) is at least one bifunctional epoxy resin which is obtained by reacting any one selected from the group consisting of bisphenol A, bisphenol F, and tetrabromobisphenol A with epichlorohydrin and has an n=0 component content as determined from a GPC chart of 60% or higher.

Abstract: To enhance the tear strength without increasing the thickness, a woven glass cloth having a mass of 15 to 30 g/m.sup.2, for use as a base material for printed wiring board material, is characterized in that the weft or warp is provided by a 75 denier or more strand, thicker than the warp, and thread count of the thicker strand per unit length is set smaller than that of the other strand.

Abstract: An internal composite layer for a multilayer circuit board, which is composed of an electrically insulating substrate with a copper layer formed thereon and a film of a coupling agent covering the copper layer is fabricated in accordance with the following method. That is, the copper layer is treated with a base or the base and an accelerating agent to supply hydroxyl groups to a surface thereof. Subsequently, thus treated copper layer is coated with the coupling agent, e.g., a silane coupling agent. The coupling agent is chemically bonded to the treated copper layer by the reaction of the hydroxyl groups with the coupling agent, so that an adhesion strength between the copper layer and the coupling agent is remarkably increased. In addition, since it is not necessary for forming a copper oxide layer in the surface of the copper layer, the internal composite layer shows excellent acid resistance without causing a pink-ring which usually occur around a through-hole plating.