EPOXY RESIN COMPOSITION FOR PREPREG, PREPREG, AND MULTILAYEREDPRINTED WIRING BOARD

摘要

Problems: To provide an epoxy resin composition for prepreg used in manufacturing a printed wiring board, particularly a multilayered printed wiring board, which does not generate toxic substance on combustion and excellent in ignition resistance, solder heat resistance after moisture absorption and high temperature rigidity, prepregs and multilayered printed wiring boards. Means for solving problems: A phosphorous compound comprising 1.8 or more but less than 3 phenolic hydroxyl groups on an average and 0.8 or more phosphorous atom on an average within a molecule is reacted in advance with a particular bifunctional epoxy resin (selected from biphenyl, naphthalene, dicylcopentadiene or other types) in a ratio of epoxy equivalent to phenolic hydroxyl equivalent to be 1.2 or more but less than 3 to 1 to yield a preliminarily reacted epoxy resin, of which 20% by mass to 55% by mass against the whole epoxy resin composition is formulated together with a multifunctional epoxy resin having 2.8 or more epoxy groups on an average within a molecule, a curing agent comprising dicyandiamide and/or multifunctional phenolic compound and an inorganic filler with thermal decomposition temperature of 400°C or above, yielding an epoxy resin composition which is used to prepare prepregs used in manufacturing a printed wiring board.