Searching for appropriate humidity accelerated migration reliability tests methods

Lifetime estimation is one of today's frequently used reliability testing tool. There are standardized test methods, mathematical apparatus and failure acceleration models for predicting failure rate of electronic components, circuit modules or equipment. Do the widespread used models give a precise description for all kind of failure mechanisms? Can they define the acceleration factor of any test, and the accelerated lifetime of any test vehicles? In connection with open surface migration tests (when the test circuit samples are not covered by any protective or packaging material) two climatic test methods (Thermal Humidity Bias––THB test methods with different parameter settings) have been compared: 40 °C/95%RH suggested by ''a well known IEC standard'' and 85 °C/85%RH required by the newer JEDEC standard. The novelty of the paper is the comparison between the two climatic test methods. The main conclusion is a suggestion to keep on with the old method in the mentioned particular case, which may be shocking for people who prefer the new standards. All conclusions are strengthened both with theoretical and experimental test results.