The Investigation and Improvement on the On-Line Images Inspection of BGA

• Main Authors: Chia-Liang Chen, 陳佳良
• Other Authors: An-Chen Lee
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/15737791031751727459

碩士 === 國立交通大學 === 機械工程系 === 89 === The purpose of this thesis is to improve a preliminary developed BGA(Ball Grid Arrays) inspection system. The contents first provide an overview on all kinds of flaws of the BGA devices, then introduce new rules for defect detection. By comparing results of different methods for each image processing steps of inspection procedure, we try to look for more suitable ways. We find out that the most suitable threshold value for image segmentation and a better sub-pixel edge-detect operator would be helpful to upgrade the original system. To improve inspection efficiency, we use least-square error circle fitting method to approximate the shape of solder balls. Moreover, we introduce the definition of circularity to prevent defective solder balls from passing the inspection. To improve the functionality of the original inspection system, we provide an improvement proposal for the compensation method of the moving angle deviation of between the BGA substrate and the CCD camera during the image capture procedure. Finally, the contents have complete introduction for system calibration, which can aid the implementation of the BGA inspection. The final outcomes show that the upgraded system not only successfully inspects BGA devices with no correct position, but also has more stability in size measurements. It takes the upgraded system only 0.3 seconds to complete inspection of a BGA device with 336 solder balls of 0.63mm diameter. This is 4 times faster than the original system.