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Standard drop tests for portable electronics are not representative for the qualification of automotive electronics. High-frequency vibrations are more dominant than abrupt shocks during normal operation. In this work a high speed board bending (HSB) method is developed to mimic the constant cyclic solder joint loading (sinus wave load, 10-200 Hz, <;2 mm peak-to-peak). A series of test printed circuit boards with wafer level chip scale packages (WLCSP) and Micropearl SOL lead-free solder balls arrays are daisy-chain interconnected and in-situ monitored to detect failure during loading. After failure defect interconnects are cross sectioned for fractography to determine the corresponding failure mechanism. To determine the maximum stress and strain levels finite element modeling (FEM) is used and compared with the results from HSB testing. Finally, a proof of concept is done for the high speed bending test. Further verification is necessary to use this test as qualification for 2nd level interconnect qualification of automotive electronics.
Date of Conference: 12-15 Sept. 2011