Red Room - Session 11
9:10 to 10:10 a.m. Thursday, June 5, 2014
The Reliability Assessment of a Low Temperature Lead Free Solder Used in a High g-Load Environment
Consumer electronics have been converted to lead-free solders as required by the RoHS directive since 2006. Our application has a flex circuit soldered to a ceramic substrate through a hot bar process. Due to material, geometry and Package-On-Package limitations, we cannot use the most commonly available lead-free paste – SAC305 – due to its high temperature requirements. Instead, we are using the indium alloy 77.2Sn 20.0In 2.8Ag, which has a similar melting point as SnPb solders.
This session presents the analysis performed by the paste supplier, the reliability tests performed on our application and the cross-section analysis to evaluate the intermetallic growth and what type of intermetallics are seen as a function of thermal cycle and high temperature storage testing. Different accelerated testing conditions will be used to estimate the solder joint life under the normal use environment.
Key Words: Lead Free, SAC305, SnInAg, Flex Interconnect, Hot Bar, Thermal Cycle, IMC, RoHS, Eutectic Tin Lead Replacement, Stacked Packaging
Reinaldo Gonzalez and Greg Zeman