Design and simulation of the Positioning System Using Computer Vision for IC Packaging
Junlan Li, Yizhong Wang, Dawei Zhang, Xingyu Zhao · 2007
A positioning system using computer vision technologies is designed to obtain high precision during wire bonding. The main processes are on-line examining the position of a chip before bonding, calculating its locating errors, and cooperating with control system to eliminate these errors. Therefore, chips' accurate positions can be obtained which can improve the technology of wire bonding. A novel optical imaging system is designed to get images with high quality. Micro-imaging system consists of two lenses to achieve appropriate magnifying multiple and working distance, which are 4 and distance is 47 mm, respectively. Illumination lens provides steady and symmetrical lighting condition on working area. Normalized correlation image registration algorithm is applied as the pattern recognition positioning algorithm of wire bonder's vision system. Some simulation experiments have been carried out, which show that the precision of pattern recognition in this system is 3.5 mum, which satisfies the requirements of wire bonding.