A Statistical Analysis Method for Image Processing Errors in the Position Alignment of BGA-type Semiconductor Packages

BGA형 반도체 패키지의 위치정렬용 영상처리기법 오차의 통계적 분석 방법

Pick and placement systems need high speeds and reliability for the position alignment process of semiconductor packages in picking up and placing them on placement trays. Image processing is usually adopted for position aligning where finding out the most suitable method is considered most important aspect of the process. This paper proposes a method for judging the performance of different image processing algorithms based on the PCI (Process Capability Index). The PCI is an index which represents the error distribution acquired from many experimental data. The bigger the index, the more reliable the results or the lower the deviation. Two compared and candidate methods are Hough Transform and PCA (Principal Component Analysis), both of which are very suitable for oblong or rectangular type packages such as BGA's. Comparing the two approaches through a CPI with enough experimental results leads to the conclusion that the PCA is much better than the Hough Transform in not only reliability, but also processing speed.