Evaluation of the drop test of isotropic electrically conductive adhesives (ICAs) using an accelerometer

A simple and effective method of quantitative analysis of the impact energy of drop testing of isotropic conductive adhesives (ICAs) by using an on-board accelerometer is described to correlate ICA failure rate with the accumulated output signal. The integration of acceleration or voltage over time during impact can be used as another index of relative total impact energy level additional to the terminal velocity or drop height. The experimental results suggest that the friction and non-uniformity of drop interactions are not negligible when applied to the National Center for Manufacturing Science (NCMS) standard, raising accuracy concerns when there is a need to compare impact strengths of ICAs by judging survival rates from dropping from a single height. With the goal of establishing of a simple test apparatus which can eliminate all sources of variation, using the accelerometer on the substrate is more efficient and versatile. The disadvantage is that the inevitable tradeoff between dynamic range and sensitivity of commercially available accelerometers limit the accuracy when they are used in higher impact level ranges.