Patent attributes
A stack of 50 layers of a first pitch-base carbon fiber sheet is formed, two sets of stack each having two second pitch-base carbon fiber sheets stacked therein are fabricated. At this time, the second carbon fiber sheets have a thermal expansion coefficient larger than that of the first carbon fiber sheet. Next, the stack of the first carbon fiber sheet is then held between two sets of stack of the second carbon fiber sheets. The stack of the first and second carbon fiber sheets are then impregnated with an epoxy-base resin composition and the resin is solidified. As a result a prepreg composed of the first and second carbon fiber sheets and the resin component composed of the epoxy-base resin composition is obtained. Thereafter, interconnections and the like are then formed on the prepreg, to thereby complete a multilevel interconnection board.
