INSPECTION OF PRINTED CIRCUIT BOARD

PURPOSE:To improve the working efficiency drastically by forming a conductive land having a pair of round land section with a specified radius to detect positional deviation through open windows of an insulation layer and a symbol printed layer depending on the presence of electric conduction. CONSTITUTION:A conductive land 3 is formed on a printed circuit board 1. The radius (r) of a round land section 4 shall be held within the maximum allowable dimensions in the positional deviation of an insulation layer 6, a symbol mark layer 11 and a part mounting hole 14. Open windows 13 and 9 are provided in the symbol mark layer 11 and the insulation layer 6 at the positions corresponding to the conductive land 3 respectively. The distance between detection pins 16 and 16 is equal to the center-to-center distance X between the round land sections 4 and 4 and the distance between the detection pin 16 and a guide pin 17 equal to the distance Y from a reference hole 15 to have the guide pin 17 inserted into the center of the conductive land 3. When there is any position deviation in the insulation layer 6 and the symbol mark layer 11, the insulation layer 6 or the symbol mark layer 11 covers near the center of the round land sections 4 and 4 to eliminate electric conduction between the detection pins 16 and 16.