Correlating field requirements to accelerated life testing for vehicle electronics

In the field of automotive electronics, a quick and accurate technique to predict the useful life of electronic modules is considered a critical tool to assure future, and existing, product designs are successful in meeting long-term life requirements. This need is particularly true for harsh environment electronics, such as transmission and engine control modules. These modules are confronted with many difficulties such as a changing thermal environment and reductions in component packaging size that are not significant problems for most other electronic products. Because these modules are designed for ten or more years of use, accelerated life testing methods are necessary for predicting product life for new designs. However, there is a very limited understanding of the relationship between accelerated life testing and product field requirements. A better understanding of this relationship is critical to future product designs. To address the testing issues associated with validating new electronic technologies, a method was created which employs a statistical procedure to link accelerated thermal cycle testing to vehicle mileage. This method was applied to hundreds of field units from DaimlerChrysler and was performed within the Center for Advanced Vehicle Electronics (CAVE) at Auburn University. By comparing the degradation between modules which were subjected to accelerated life testing and modules with only mileage, a correlation was found that could provide information into the actual performance characteristics of Accelerated Life Testing. The procedure and results of this study are provided and give a clear relationship between accelerated life testing and vehicle mileage for a thermal wall mounted product. This improved knowledge will allow ALT standards and specifications to be set to an adequate and acceptable level, potentially minimizing excessive testing while ensuring the reliability of future under-the-hood electronic technologies.