SUMMARY

Inspection of solder joint interconnection has been a crucial process in the electronics manufacturing industry to reduce manufacturing cost, improve yield, and ensure product quality and reliability. New inspection techniques are urgently needed to fill in the gap between available inspection capabilities and industry requirement of low-cost, fast-speed, and highly reliable inspection systems. The laser ultrasound inspection system under development aims to provide a solution that can overcome some of the limitations of current inspection techniques. Specifically, the fully developed system will be an automated system that is capable of inspecting hidden solder joints with multiple defect types. This research work focuses on addressing some of these existing issues to improve inspection efficiency. The approaches are to: 1) Define and optimize testing parameters through Design of Experiments and Measurement System Analysis studies. 2) Develop new signal processing algorithms to ensure fast and accurate interpretation of vibration responses. 3) Develop a finite element model to explain and predict a package assembly’s modal behavior and vibration response under laser pulse excitation, and validate this model experimentally. 4) Conduct experiments on different package formats and defect types to extend the system’s application scope. Realization of this research goal will lead to a laser ultrasound solder joint inspection system prototype with faster speed, better precision, and improved sensitivity to defects that are prevalent and hard to detect. Finite element modeling will lead to a better understanding of the laser ultrasound induced vibration in electronic packages and how it can be exploited for solder joint inspection.