MULTILAYERED PRINTED CIRCUIT BOARD

摘要

PROBLEM TO BE SOLVED: To provide of a multilayered printed circuit board of an arrangement which suppresses thermal expansion in a surface direction and reduces a thermal expansion coefficient in the surface direction, by adding a flexibilizer in epoxy resin forming an insulating layer of the board. SOLUTION: A glass fiber woven cloth having a thermal expansion coefficient of 4 ppm/ deg.C or less or aramid fiber nonwoven cloth is impregnated with epoxy resin varnish containing dispersed rubber resilient fine particles (acrylic rubber fine particles) not compatible with epoxy resin and then dried to obtain a prepreg. Eight sheets of prepregs are laminated, copper foils are placed on both sides of the laminate, and then hot-pressed to obtain a both-surface copper-foil clad laminate substrate. The copper foils are etched to form predetermined circuits and to obtain a both-sided printed circuits board. Next copper foils are placed on both sides of the both-sided printed circuit board with the same prepreg sheet disposed therebetween, hot-pressed for integration. The copper foils are etched to form predetermined circuits, thus forming a 4-layer printed circuit board.