11 a.m. - 12 p.m. Location: RL 3.204
ABSTRACT: Powder metallurgy or metal-powder sintering, which has been practiced for hundreds of years, is emerging as an advanced joining technology for manufacturing power electronics devices/modules. Compared with traditional soldered joints, sintered metal joints have the advantages of lead-free, higher thermal and electrical conductivities, higher reliability, and ability to support higher junction temperature. There are many commercial metal-powder products being marketed for die-attaching power chips. They come in different chemical formulations, particle morphologies and size distributions, and flow characteristics. In addition, there are two different versions of the bonding process, one requiring a uniaxial force, henceforth termed pressure-assisted sintering, and the other no force or pressure-less sintering. It has been extensively reported that the sintered joint performance and reliability depend strongly on the properties of the powder material, the surface finish on bonding parts, and temperature-time-pressure profile. The multitude of material and processing variables can cause confusion when deciding to implement the bonding technology. The purpose of this talk is to help the audience to gain better understanding of the joining process by reviewing fundamental principles of metal-powder sintering and adhesion at the interfaces, discussing effect of sintering atmosphere, and offering practical considerations for developing a die-attach process based on metal-powder sintering.
BIO: Dr. Guo-Quan (GQ) Lu is a professor jointly appointed between the Department of Materials Science and Engineering and the Bradley Department of Electrical and Computer Engineering at Virginia Tech. He has a double-major BS degree in Physics and MSE from Carnegie-Mellon University and Ph.D. in Applied Physics/Materials Science from Harvard University. He worked at Alcoa Technical Center before joining Virginia Tech. Since 1998, Dr. Lu has worked extensively on research projects in the Center for Power Electronics Systems (CPES) at Virginia Tech. His research activities and interests include synthesis and processing of functional materials and development of electronic packaging technologies for power electronics integration. Dr. Lu has published over 100 peer-reviewed journal articles and over 100 papers in conference proceedings. In 1995, he won a Virginia Tech teaching award and a National Science Foundation CAREER award. His development of nanoscale silver paste, nanoTach®, for low-temperature joining of semiconductor chips was recognized with a R&D 100 award in 2007. Dr. Lu is an IEEE Fellow.
Jennifer Alsbury, 972-883-5754
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