Physics of Failure as an Integrated Part of Design for Reliability

A study of the use of Physics of Failure (PoF) methods was undertaken as part of a collaboratively funded United Kingdom Government Department of Industry (UK DTI) project for developing a holistic methodology and assessment model for the enhancement of electronics reliability. Several case studies were conducted to review the use of PoF techniques. The study concluded PoF methods, and in particular life modeling, are essential tools in design for reliability. PoF analysis can also be used to establish reliability enhancement testing (RET) and environmental stress screening (ESS) conditions. A guide for the effective use and inclusion of the PoF methods in the product design and development process was developed and described. Use of the techniques facilitates accurate design right, thereby avoiding redesign and retest cycles, with consequent cost savings and reduced product development times. The PoF method has limitations. It is essentially a bottom-up approach assessing time to failure due to known failure mechanisms. Consequently, it is difficult to apply to full systems, has limitations in assessing failure rate prior to the onset of life-limiting wear out, and is dependent on identifying and having a validated model for all potential failure mechanisms.