| 摘要 |
<p>Holes (40a) are formed with a laser beam through an insulating substrate (40) on which a metallic layer (42) if formed. After the holes (40A) are formed, via holes (36a) are formed by filling up the holes (40a) with a metal (46) and a conductor circuit (32a) is formed by etching the metallic layer (42). Then, a single-sided circuit board (30A)is formed by forming projecting conductors (38a) on the surfaces of the via holes (36a). The projecting conductors (38a) of the circuit board (30A) are put on the conductor circuit (32b) of another single-sided circuit board (30B) with adhesive layers (50) composed of an uncured resin in between and heated and pressed against the circuit (32b). The projecting conductors (38a) get in the uncured resin by pushing aside the resin and are electrically connected to the circuit (32b). Since single-sided circuit boards (30A, 30B, 30C, and 30D) can be inspected for defective parts before the boards (30A, 30B, 30C, and 30D) are laminated upon another, only defectless single-sided circuit boards can be used in the step of lamination. <IMAGE></p> |
