SUBJECT: Ph.D. Proposal Presentation
BY: Jin Yang
TIME: Thursday, January 24, 2008, 9:30 a.m.
PLACE: MARC Building, 401
TITLE: Quality Inspection and Reliability Study of Solder Bumps in Packaged Electronic Devices: Using Laser Ultrasound and Finite Element Methods
COMMITTEE: Dr. I. Charles Ume, Chair (ME)
Dr. Steven Danyluk (ME)
Dr. Suresh K. Sitaraman (ME)
Dr. Jye-Chyi (JC) Lu (ISYE)
Dr. Thomas E. Michaels (ECE)
Dr. Deepak Goyal (Intel)


The transition from traditional through-hole assembly to surface mount assembly is a significant step in evolution of electronic packaging. The use of surface mount devices has helped to decrease size of electronic packages through use of solder bumps between devices and substrates/PWBs. Common manufacturing defects-such as open, cracked, missing, and misaligned solder bumps–are difficult to detect because solder bumps are hidden between device and substrate/PWB. Quality inspection of solder bumps has been an important process. Current techniques available for inspecting solder bumps include: 1)electrical testing 2)X-Ray inspection and 3)acoustic inspection. They do not necessarily encompass all capabilities for evaluating quality of solder bumps. New inspection techniques are urgently needed to fill gap between available inspection capabilities and industry requirements of noncontact, nondestructive inspection systems. The laser ultrasound inspection system under development aims to provide a solution that can overcome some limitations of current inspection techniques. Some research issues still need to be addressed before system can be ready for industrial use. Main objectives of this work include:1) Develop new signal-processing methods for analyzing transient signals to improve inspection accuracy and sensitivity, inclduing wavelet analysis and local temporal coherence analysis.2) Develop an integrated analytical, numerical, and experimental modal analysis method to predict modal behavior and defect effects on structural characteristics of PEDs.3) Develop an FE model for predicting presence of defects in thermomechanical reliability testing of FCPs. Failure of FCPs can be estimated based on strain or strain energy density criterion. Simulation results will be validated with experimental results 4) Conduct experiments on test vehicles with different package formats and defect types to expand application scope.