Automatic detection of drilling holes in PC boards

A system to detect drilling hole positions in PC-board masks is described. The masks are scanned by a mechanical moving stage scanner. Both scan-control and detection of the rings that indicate the drilling positions are performed by an INTEL 8030 microprocessor system. After determination of the effective board size and the reference position of the 1/20-inch (1.27mm) drilling grid, scanning along this grid starts recognising the rings at the drilling positions. The prototype scans a board of size 100 x 160 mm (Eurocard size) in 10 minutes.