Effect of Shock Angle on Solder-Joint Reliability of Potted Assemblies Under High-G Shock

Abstract

Commercial off-the-shelf components are increasingly being used in defense and aerospace applications. Harsh environment applications expose the electronic components to high-g shock forces. In order to assess the accelerated test reliability, most of the tests are performed at a zero degree drop angle as the worst case scenario. However, the drop angle in the actual environment is not always exactly zero degree and systems may be subjected to angular impact. With the variation in the drop angle, the effect of drop on the board changes. The reliability of the electronic components and the solder-joint interconnects, may depend on the effect of drop angle on the test vehicle. Tools for assessment of the effect of drop-orientation will provide insights into the detrimental shock-orientations and create accelerated tests more relatable to actual shock environments in real life. A potted circular PCB is used as the test vehicle, potting is done to understand the effect of drop angle on restraint mechanisms. Results on a circular PCB have been reported for three different drop angles of shock 0-degree, 30-degree and 60-degree. The experiments are performed and reported for two different high-g shock levels of 10,000G and 25000G. An explicit finite element model has been created for the board assemblies and out-of-plane displacement contours are compared to verify trend observed in experiment on the effect of change in drop angles.