Laser spallation adhesion metrology for electronic packaging development

In this paper, the merits of the laser spallation (LS) technique are described and demonstrated with regard to next-generation flip-chip packaging development. LS is based on conversion of a laser pulse into a mechanical stress pulse on the backside of a sample, which can spall films on the front side if of sufficient amplitude. One significant advantage of LS over traditional adhesion metrologies is that actual components can be evaluated, improving throughput and eliminating process-matching issues associated with making test coupons. Other advantages and case studies involving test-vehicle die and package-side applications are discussed.