Abstract
Since bend and height errors of QFP IC leads cause assembly defects of components loaded on PCBs. A technique to inspect these errors in QFP ICs is indispensable. An inspection method for QFP IC using a 3-D vision sensor and a television camera has been developed. In the inspection method, the height of leads and the distance between leads, that is referred to as the pitch, are measured by the especially designed 3-D vision sensor. The lead length, which is the distance between the tips of confronting leads, is measured by the television camera. The 3-D vision sensor measures the height and pitch by triangulation with a slit light. In the measurement, slit light projection power and position are controlled in order to restrain the effect of solid dip coating on the lead surface.
The developed system containing these algorisms inspects a 44pin QFP IC with a measurement accuracy of ±0.02mm and an inspection time of 7 seconds.
