| 摘要 |
A METAL LAYER (18) IS SANDWICHED BETWEEN INSULATING LAYERS (14, 20) SO THAT REQUIRED STRENGTH IS MAINTAINED. HENCE IT FOLLOWS THAT THE THICKNESS OF A CORE SUBSTRATE (30) CAN BE REDUCED AND, THEREFORE, THE THICKNESS OF A MULTI-LAYER PRINTED CIRCUIT BOARD CAN BE REDUCED. FORMATION OF NON-PENETRATING OPENINGS (22) WHICH REACH THE METAL LAYER (18) IN THE INSULATING LAYERS (14.20) IS SIMPLY REQUIRED. THEREFORE, SMALL NON-PENETRATING OPENINGS (22) CAN EASILY BE FORMED BY APPLYING LASER BEAMS. THUS, THROUGH HOLES (36) EACH HAVING A SMALL DIAMETER CAN BE FORMED.(FIG 1(A)-(E)) |
