| 摘要 |
PROBLEM TO BE SOLVED: To enhance wiring density by forming a circuit conductor composed of an electroless plating layer on the surface of an insulating layer and further forming a via composed of conductive paste to which the circuit conductor is to be connected in a different layer. SOLUTION: Insulating adhesive 1 is irradiated with laser light in a specified position to form a through hole 2 there and the through hole 2 is filled with conductive paste 3 composed of copper filler and phenol binder by screen printing, which conductive paste is then cured. Thereafter, the surface of the insulating adhesive 1 filled with the conductive paste 3 is flattened by buff polishing and the surface of the insulating adhesive 1 is subjected to roughing 8. At the same time, the surface of the insulating adhesive 1 is activated by catalysis. The surface is exposed to ultraviolet rays through a photomask masking places to be subjected to electroless plating and developed to form resist 4. Further, the workpiece is immersed in electroless plating liquid under specified conditions to form circuit conductors 6.
|
