(Dr. Charles Ume, advisor)
"Design and Integration of a Large Area Warpage Measurement System"
New techniques and technologies involved in the miniaturization of printed wiring board (PWB) fabrication are rapidly emerging. The quality, performance, and reliability of surface mount assemblies built on these next-generation boards will depend on many factors, including thermally induced warpage. Therefore, PWB design evaluation needs to include thermo-mechanical performance derived from quantitative warpage measurements.
In order to expand the current capabilities of measuring thermally induced PWB warpage at Georgia Tech, a new highly automated large-area warpage measurement system has been developed. The system can accommodate samples up to 24” X 24” in size. Enhanced shadow moire` measurement technology, known as the phase-stepping technique, is used to obtain fast, out-of-plane displacement measurements with sub-mil resolution. The advanced software interface allows for computer-controlled specimen positioning, direct-to-disk automated image capturing and real-time display of 3-D warpage surface plots at any desired temperature during a profile. Results from the warpage measurement of two samples heated under an industry standard profile are shown to demonstrate system operation and performance. Heating chamber thermal characteristics were obtained during repeated heat cycles performed to optimize the reflow profile simulation.