Solder Joint Fatigue Testing with Harsh Temperature Rates: Influence of Dwell Time

Inhalt:
Solder joint fatigue is seen as a crucial aspect of the reliability of an electronic product. This holds especially for applications with high requirements within the industrial, automotive or aerospace environment. Especially automotive requirements are currently under re-calibration due to the changed operating modes of electric cars. Enhanced requirements on board level reliability are accompanied with increasing testing time. Harsher conditions have to be applied during testing to keep established timescales for qualification. But therefore, more knowledge has to be generated on the resulting failure mechanism, the influence on joint lifetime and the applicability of lifetime models. In the first part of this investigation, a quantitative acceleration factor between liquid-liquid and air to air thermal shock testing for equal dwell times is derived from the experiments. The harsh ramp in the liquid-liquid testing leads to a decreased joint lifetime. In a second step, it is shown that reducing the dwell times in liquid-liquid testing can even invert the outcome of the test. In this case, the reduction of dwell time resulted in 20 % higher cycles to failure (CTF) than the classical air to air thermal shock loading conditions.