Side impact reliability of micro-switches

In this study, a novel side-impact test method is developed for shearing-off miniature electromechanical devices from the printed wiring boards (PWBs) of portable products. The test method is implemented by modifying a commercial IZOD pendulum impact test setup. The key modification is the replacement of the instrumented pendulum impactor with an instrumented “striker-bar” design. The pendulum instrumented with the “striker-bar” allows high impact velocity up to 3.54E+3 mm/s, and is specially designed for testing components with very low profile. In this study, this setup is used to test a miniaturized electromechanical devices, such as a micro-switch, whose low profile presents a significant challenge to repeatable side-impact testing. Both overstress impact tests and repetitive impact fatigue tests are conducted, to evaluate the interaction of the different parts of the entire electromechanical assembly, including the solder joints, pins, through-holes and housing of the package. Failure modes are documented and failure envelopes are developed by relating the measured durability to the impact parameters like impact velocity, fracture energy and force impulse.