| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of the damage to and peeling of a plated film from the inner peripheral surface of a through-hole, and to prevent an increase in a production cost. SOLUTION: Holes 2a to 2c for the through-hole are formed on a plurality of insulating boards 1a to 1c, the diameters of the holes 2a to 2c are set in 1, 1.5 and 2 mm respectively and wiring layers 3 are formed on both surfaces of the insulating boards 1a to 1c. The insulating boards 1a to 1c are bonded with an adhesive 4, and copper plating films 5 are formed on the inner peripheral surfaces of the holes 2a to 2c. Consequently, the through-hole 6 having stepped cross sections is formed, solder coatings 7 are formed on the inner peripheral surface of the through-hole 6 and stepped differences in the through-hole 6 are buried with solder coatings 7. COPYRIGHT: (C)2007,JPO&INPIT |
