High Frequency Effects on the PBGA Stress Developments at Random Vibration

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 extreme levels of the random vibrations were applied sequentially in the vibration tests to investigate the sustainability of the PBGA chips mounted on the polyimide PCB with aluminum frame. The test results did not show any solder failure under the test conditions, indicating the robust structural integrity and providing the evidences justifying the PBGA packaging to the aerospace applications. Numerical analyses were also performed for the solder stress developments, demonstrating that the first natural mode was not necessarily the dominant source for the maximum solder stress, and the usual assumption that the center of the PCB center could be bad choice for the chip mounting might be wrong. The calculations represented the locations away from the PCB center could be worse due to the higher frequency natural mode contributions to the stress developments.