CIRCUIT BOARD, INSULATION MATERIAL THEREFOR, AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a circuit board that is in interstitial via hole structure and stiff, its manufacturing method, and to provide an insulation material for the circuit board. SOLUTION: The insulation material is made of a porous base with at least three layers where reinforcing materials 401 and 402 are laminated on both the surfaces of the insulation material 402 that has been semi-cured by impregnating a thermosetting resin, and the empty hole rate of the porous bases is allowed to differ between the outermost layers 401 and 403, and the inner layer 402. The empty hole rate of the porous base of the outermost layers 401 and 403 is preferably smaller than that of the inner layer 402. A wiring layer 404 is formed on both the surfaces of the insulation layer, and conductive paste 405 is filled between the wiring layers 404 for conducting electricity.