Harmonic Vibration Durability Tests on Lead-Free Solder Joints at Different Isothermal Conditions

The results on a unique double-cantilever test specimen that has been designed specifically for combined temperature/vibration testing are reported in this study. This specimen consists of two symmetric sets of 4 identical cantilever beams. In prior studies with this double-cantilever test specimen, all the solder joints were stressed to the same level. Thus, a test on one specimen resulted in a single data point on the fatigue curve. In the present study a modification of the double-cantilever test setup is presented which results in a different resonant frequency for each of the two cantilever sets. The asymmetric response produces two different cyclic strain levels in the solder joints on each of the two cantilever sets. Furthermore, a test setup adaption for simultaneous excitation of two test specimens allows four different stress levels in each vibration test. This allows significant time-savings in fatigue testing, compared to sequential testing of four different specimens. Vibration durability results under isothermal conditions are presented, and the potential ability for future experiments with superimposed temperature cycling on vibration is discussed.