MSE Seminar Series: Michael Osterman
Friday, October 28, 2011
Room 2110 Chemical and Nuclear Engineering Bldg.
301 405 5240
Issues Arising from Lead-free Materials on Electronics Assemblies
Senior Research Scientist
Center for Advanced Life Cycle Engineering (CALCE)
Department of Mechanical Engineering
University of Maryland
Presented by the Materials Science Graduate Society.
Concerns over human health and environmental impact have resulted in several countries restricting or banning select materials from use in the construction of electronic products and systems. Restricted materials include lead, mercury, hexavalent chromium, cadmium, polybrominated biphenyl (PBB) and polybrominated diphenylethers (PBDE), with others being proposed. While electronics used for defense systems have been excluded from these government regulations, the globalization and commercialization of electronics make the exclusion relatively miniscule. Of the restricted materials, the removal of lead has resulted in perhaps the most dramatic change.
While electronic equipment manufacturers can still obtain eutectic tin lead solder, the availability of parts with tin-lead terminal finishes is diminishing and cost and lead times to obtain parts with tin-lead finished parts is rising. As such, equipment manufacturers must determine the impact on product reliability due to converting completely to lead free materials, determine the impact on product reliability by using parts with lead-free terminal finishes in tin-lead soldered assemblies, and/or determine the reliability risk of converting lead-free terminals to tin-lead finished terminals. Issues and risks are present independent of selected direction taken by the equipment manufacturer. With regards to using lead-free materials, manufacturer must consider the risk of failure due to tin whiskers. Assembling ball grid array parts with lead-free solder sphere in a tin lead reflow assembly process can lead to compromised solder joint reliability. Assemblies constructed with the currently popular lead-free solder tend to have a lower shock/drop interconnect durability. Higher processing temperature associated with using lead-free solder can give rise to manufacturing and reliability issues. Current methods for assessing the results of tests used to qualify electronic equipment must be revised based on the physical understanding of the behavior of the new lead-free material set.
This presentation will review potential issues with using lead-free materials in electronic products and some of the research findings that have been made.
About the Speaker
Dr. Michael Osterman (Ph.D. Mechanical Engineering, University of Maryland, College Park) is a Senior Research Scientist and the director of the CALCE Electronic Products and System Consortium at the University of Maryland. He heads the development of simulation assisted reliability assessment software for CALCE and simulation approaches for estimating time to failure of electronic hardware under test and field conditions. Dr. Osterman has assisted companies with transition to lead-free and in simulation based assessment of electronic assemblies. In addition, he has lead CALCE in the study of tin whiskers since 2002 and has authored many key articles related to the tin whisker phenomenon. Dr. Osterman served as a subject matter expert on phase I and II of the Lead-free Manhattan Project sponsored by Office of Naval Research in conjunction with the Joint Defense Manufacturing Technical Panel (JDMTP). Further, he has written various book chapters and more than seventy articles in the area of electronic products and systems reliability. He is a member of ASME, IEEE, and SMTA.