| 摘要 |
PROBLEM TO BE SOLVED: To make favorable testable the continuity of printed wirings formed on both faces of a substrate. SOLUTION: A printed circuit board 11 is formed so that a printed wiring 121 on the rear face and a printed wiring 122 on the front face connect with each other via a through hole 13. A first plane electrode 31 is arranged opposite to the end part 124 of the printed wiring 122 of the front face. A second plane electrode 32 is arranged opposite to a part of the printed wiring 122 of the front face between the end part 124 and the through hole 13. An electric signal changing the level with time is impressed to an end part 123 of the printed wiring 121 by a voltage impress means 51 and a forward amplifier 52 of a signal impress means 50. At the same time, an electric signal changing a level in an opposite phase to the electric signal is impressed to the second plane electrode 32. Whether a connection state between the end parts 123 and 124 is good or not is judged by a connection judge means 60 based on an electric signal generated to the first plane electrode 31 when these electric signals are impressed.
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