Here is the abstract you requested from the IMAPS_2012 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|Evaluating the Impact of Dwell Time on Solder Interconnect Durability under Bending Loads|
|Keywords: Solder Interconnect Reliability, Cyclic Bending Test, Fatigue Life Estimation|
|With increased portability and miniaturization of modern day electronics the mechanical robustness of these systems has become more of a concern. Existing standards for conducting mechanical durability studies in electronic assemblies include bend, shock/drop, vibration and so on. Though these standards provide insights into the cyclic fatigue damage incurred in the solder interconnects (widely regarded as the primary mode of failure in electronic assemblies), they fail to address the impact of sustained mechanical loads on the solder interconnect durability. It has been seen that the solder durability under thermal cycling loads decreases with an increase in dwell time of cycling. Fatigue life models, which include the dwell time, have been developed for solder interconnects subject to temperature cycling. However the fatigue life models that have been developed in literature for solder interconnects under mechanical loads fail to address the impact of dwell time of loading. In this study the test vehicles were subjected to cyclic mechanical bending with varying dwell times. The solder interconnects examined in this study were formed with 2512 resistor packages using varying solder compositions (SnPb and SAC305). In order to evaluate the impact of dwell time, the boards were tested with a 60 second and a 300 second dwell time on both extremes of the loading profile. It was observed that an increase in dwell time of the loading profile resulted in a decrease in the characteristic life of the solder interconnects. FEA models were developed which included the fatigue properties of the solder in order to evaluate the cyclic strain experienced at the solder interconnect during the cyclic bending. Based on these test results, a new fatigue life estimation model was developed for mechanical loads which included the impact of dwell time.|
|Sandeep Menon, Graduate Research Assistant
CALCE, University of Maryland
College Park, MD