Endoscopic inspection of solder joint integrity in chip scale packages

This paper reports the use of endoscopy for the nondestructive examination of solder joint integrity in chip scale packages (CSP) such as flip chip on flex. Borrowed from the medical instrument technology, the endoscope is used to examine visually the inside of an organ. This concept has now been developed and refined by ERSA and KURTZ, and led to an ERSASCOPE inspection system coupled with sophisticated but user-friendly software for data and image analysis. We have successfully used this endoscopic method to evaluate the solder joint integrity in CSP such as cold joints, standoff height measurements, and probing of inner rows of ball joint integrity. Since this new instrument has only been introduced very recently, we will also report the latest results for obtaining the optimal examination of solder joint integrity achievable. By analyzing many varieties of CSP samples, we have witnessed the tremendous power of endoscopy when applied to the nondestructive examination of CSP solder joints, and found this method of immense use to the quality assessment of miniaturized electronic packages. We also give a critical review of this inspection method when applied to CSP