PURPOSE: To make conductive very easily through-hole formed through each ceramic circuit printed board, on which a circuit pattern is formed, by sticking the surface of each board to the back of a flexible printed circuit board and then rendering them to solder dipping.

CONSTITUTION: A flexible printed circuit(FPC) board 10 includes a conductive layer 12 whose wiring is patterned on a high polymer film 11 comprising polyimide resin and the like. The back of the FPC board 10 is sticked to the surface of a ceramic circuit printed(CCP) board 8 via an adhesive 13. Conductive layers 7, 12 are made electrically conductive by a soldering process 16 such as solder dipping or reflowing. In addition, an IC bear chip 17 is bonded between whole electrodes 5, 5. And, a molded IC 18 and a chip capacitor 19, etc., are soldered between contact electrodes 4, 4. Hereby, a multi-layer substrate 1 is formed. Here, the IC bear chip 17 is protected by a resin coating 17a. By sticking the flexible FPC substrate 10 to the surface of the CCP substrate 8 which facilitates the formation of the through-hole 3, the multi-layer substrate 1 can be formed with ease.