Extraction of Solder Constituent from CSP Boards by Means of X-ray Energy Subtraction Method

With the high requirement of high-density packaging, CSP have been spread widely. To inspect the solder joint in CSP, an X-ray image has been used. However, an X-ray image contains not only solder joint but also capper leads. Therefore, it is very difficult to analyze the solder with robustness. In this paper, we propose a new method for extracting the solder constituent by means of Energy Subtraction. In the experience, we compared the performance of thick measurement between regular X-ray Image and Subtraction image. The result shows the advantageous performance of Subtraction method over regular one.