PRINTED WIRING BOARD COMPRISING A CONDUCTIVE PATTERN RETREATING AT LEAST PARTLY IN A THROUGH-HOLE

摘要

In a printed wiring board having an outwardly flaring through-hole, a conductive pattern is formed on the inwardly directed surface of the hole so as to reach a principal surface of the board only at that circumferential portion of the hole where the pattern is continuous to a pattern portion, if any, formed on the principal surface. The pattern is formed in the throughhole by positive use of that portion of a photoresist film formed on the principal surface to cover the hole which partly protrudes into the hole.