| 摘要 |
PROBLEM TO BE SOLVED: To prevent warpage of a circuit board. SOLUTION: A copper plate 21 is formed in with a through-hole 22, epoxy resin 23 is buried in the through-hole 22, copper foils 25 are clad on the copper plate 21 through polyimide resin layers 24a having a solvent dissolved therein, the copper foils 25 are selectively etched, copper foils 26 are clad on the laminate through polyimide resin layer 24v at both its sides, the copper foils 26 are partially wet-etched to expose polyimide resin layers 24, and the exposed layers 24 are irradiated with laser beam to thereby make connecting holes 27 in the copper foils 26 and polyimide resin layers 24. The laminate is subjected to an electroless plating process of copper and then to an electroplating process of copper to form copper plated layers on both the sides of the laminate, and then the copper foils 26 and copper-plated layers are selectively etched. |
