1. Sn-rich Pb-free solders are currently being utilized as replacement materials for Pb-rich solders in consumer microelectronics. During it’s service life an electronic device may experience mechanical shock, e.g., when a laptop computer is accidentally dropped from a small height. Our research focuses on quantifying the mechanical shock behavior of Pb-free solders. Understanding the mechanical shock behavior is crucial for designing microelectronic assemblies with superior reliability. High Strain Rate Behavior of Environmentally-Benign Pb-free Solders Nikhilesh Chawla, Arizona State University, DMR 0805144 Digital Image Correlation (DIC) Load Frame Phantom High Speed Camera Video Imaging Phantom Miro2 High Speed Camera (40  s exposure per frame) 1 cm Sn-3.9Ag-0.7Cu Tested at a Strain Rate of 10 s -1 (Local strain measurement, note formation of double necking) 2 1 3 ε 11

2. The PI has actively recruited women and minorities to work on NSF-funded projects. Kyle Yazzie (shown in the picture on the right) is a Native American graduate student working on this project. Kyle got his Bachelor’s degree in Materials Science and Engineering from MIT High Strain Rate Behavior of Environmentally-Benign Pb-free Solders Nikhilesh Chawla, Arizona State University, DMR 0805144

3. The integrated experimental and modeling efforts will provide a meaningful and quantitative understanding of dynamic behavior of Pb-free solders in electronic package and benefit the designers on developing reliable life prediction methodologies. Finite element simulation of a double necking when a bar subject to dynamic tensile loading Continuum modeling of interfacial strength between solder and copper based on embedded- atom potential Advantage of this approach: able to capture the nanoscale feature of the interface on the average sense

4. High Strain Rate Behavior of Environmentally-Benign Pb-free Solders Nikhilesh Chawla, Arizona State University, DMR 0805144 Outreach to minority students: The co-PI is working with Diné College from the Navajo Indian Reservation to invite Native American students to do research via ASU’s American Indian Program (AIP) Summer Bridge Program.