| 摘要 |
PURPOSE:To enable a printed wiring board to absorb residual stress by a groove so as to be protected against warpage even if the board is subjected to hot pressing by a method wherein a groove is provided to an inner board or an outer board. CONSTITUTION:An inner board 4 of a copper plated laminated board is etched for the formation of a circuit pattern 7, and a groove 11 is formed on the part of the board 4 where a copper foil is not provided. On the other hand, outer boards 2 and 3 formed of insulating boards plated with copper foils are laminated on the inner board 4 through the intermediary of adhesive agents 12 and 13, and the adhesive agents 12 and 13 are cured by hot pressing to form the boards into one piece. The copper foils of the outer boards 2 and 3 are etched into circuit patterns 5 and 6 for the formation of a printed wiring board 1. As mentioned above, as the groove 11 is provided to the inner board 4, residual stress induced by the expansion coefficient difference between the boards 2, 3, and 4 owing to the difference between the copper residues on their surfaces is absorbed by the groove 11, so that the board 1 can be protected against warpage. |
