The application of underfill materials for board level assembly has been increasing rapidly in semiconductor industry to enhance strength and reliability performance of semiconductor components in harsh environments. However, due to the intractability of the capillary underfill after curing, extracting a chip scale package (CSP) device from a printed circuit board (PCB) with a combination of mold compound and capillary underfill for ATE testing has become difficult and challenging. This poses a severe limitation to this technology regarding electrical testing and failure analysis. In order to address the challenge in extracting a CSP device from an underfilled PCB without inducing any mechanical damage, a series of sample preparation techniques has been introduced. This paper discusses the techniques in removing the fine pitch CSP device from underfilled PCB module in a relatively simple way which includes application of chemical solutions, de-soldering, residual solder remnants cleaning and reballing. The established process enables ATE testing, electrical testing and failure analysis to be performed on any CSP devices. An electrical evaluation on the efficiency of a CSP device after a series of sample preparation processes will also be highlighted.