Fatigue testing of a component lead in a plated through hole

A study to relate printed-wiring-board life as a function of solder joint fatigue is reported on. The results of the study indicate that the solderability of leads have a significant impact on reliability. All of the test specimens had bright and shiny solder fillets; this is found to be an unreliable inspection criteria for quality control. It is concluded that additional testing needs to be done at the lower deflection levels to determine the shape of the S-N curve. Testing with different levels of known lead solderability would help quantify the effect of solderability on life. It is suggested that joints be formed with more conventional techniques such as vapor-phase soldering or wave soldering