Analyses on the large size PBGA packaging reliability under random vibrations for space applications

초록

Large size commercially available plastic ball grid array chip packaging was tested and analyzed under random vibration to access its application feasibility on satellite electronics. Two types of the PBGA of 16 mm x 16 mm and 10 mm x 10 mm were chosen, and the chips were surface mounted without underfill on a daisy chained polyimide printed circuit boards. Then the boards were installed to an aluminum frame, a common type used to fix the boards to satellite structure, and undergone the random vibration tests. Two extreme levels of the random vibrations, the power spectrum of which were 22.48 grms and 31.78 grms, were applied sequentially to investigate the sustainability. It was found that the WA results did not show any solder failure under the test conditions, indicating the robust structural integrity and providing the evidences justifying the PBGA packaging feasibility to the aerospace applications. Numerical analyses were also performed to analyze the PCB vibration behaviors and stress development mechanisms. The analyses results showed that, unlike usual expectation, the first natural mode may not be the dominant contribution to the solder stress developments, and higher natural modes could induce the maximum stress depending on the chip size and its location.

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