Abstract The continuing evolution of semiconductor packages to finer solder ball pitches, shrinking solder ball volume, and new solder materials, mandates the availability of methods to accurately assess solder joint reliability both at the component and at the board level. Many tests in use for this purpose cannot provide direct measurements of solder joint interfacial strength. This paper reports on the investigation of laser spallation for interfacial strength assessments and understanding of failure mechanisms on chip scale package (CSP) solder joints.