| 摘要 |
PURPOSE:To improve the quality of the title board by eliminating any contamination on surfaces of a stainless sheet and a copper foil by forming a recess or a slit in the peripheral edge of an inner layer material, the recess or slit absorbing a resin fraction flowing out from a prepreg. CONSTITUTION:A recess 15 comprising a U-shaped groove is provided on the peripheral edge of a surface of an inner layer material 11 including inner layer conductors 21a-21f. Outer layer conductors 41a-41f are formed on upper and lower portions of the inner layer material 11 through prepregs 31, 31'. Since the recess 51 has been formed in the peripheral edge of the inner layer material 11, resin fractions of the prepregs 31', 31' gellated upon lamination and molding flow into the recess without flowing out to the outside from the end surface. Hereby, any contamination on the surfaces of the stainless sheet and copper foil are eliminated to improve the quality of the title board. |
