New automatic through hole inspection techniques for printed wiring boards (PWBs) were developed. The new method called Leakage Light Detection can detect defects such as cracks and breaks in plating of through holes with aspect ratio as large as ten. A prototype system for automatic through hole inspection is constructed, based on these techniques. This system detects defects in a 250 mm × 250 mm area of a PWB in 8 minutes.

The paper discusses pattern recognition techniques for automatic hybrid IC assembling systems. The problems concerning recognition systems are flexibility and high recognition rates for various object patterns comprised of hybrid ICs. To overcome these problems we developed two new recognition algorithms based on pattern matching methods. One method recognizes speckle pattern (printed thick-film conductor patterns) locations using matrix filtering. The other method increases the matching SNR to 4.5 times greater than previous methods using peak sharpening of the matching degree curve. These algorithms enable recognition of more than 99% (99.8% on average) of all semiconductor chip patterns (ICs, transistors, and diodes) and printed thick-film conductor patterns.