Probabilistic design-for-reliability concept and novel approach to qualification testing of aerospace electronic products

Qualification testing (QT) is the major means to make a viable device into a reliable product. The short-term goal of a particular electronic device manufacturer is to conduct and pass the established QT, without questioning if they are adequate. The ultimate long-term goal of electronic industries, whether aerospace, military, or commercial, regardless of a particular manufacturer or a product, is to make their deliverables reliable in the actual operations. It is well known, however, that today's electronic devices that passed the existing QT often fail in the field (in operation conditions). Are the existing QT specifications adequate? Do electronic industries need new approaches to qualify their devices into products? Could the existing QT specifications and practices be improved to an extent that if the device passed the QT, there is a quantifiable way to assure that its performance will be satisfactory? At the same time, there is a perception, perhaps, a substantiated one, that some electronic products “never fail”. It is likely that such a perception exists because these products are superfluously durable, are more robust than is needed for a particular application and, as the consequence of that, are more costly than necessary. To prove that it is indeed the case, one has to find a consistent way to quantify the level of the product robustness in the field. Then one could establish if a possible and controlled reduction in the reliability level could be translated into a significant cost reduction. We suggest a concept that enables one to provide affirmative answers to the above questions. One effective way to improve the existing QT and specs is to use the probabilistic design for reliability (PDfR) approach, and based on such an approach 1) conduct the appropriate accelerated life testing (ALT), i.e., failure oriented accelerated testing (FOAT) at both the design and the manufacturing stages, and, since ALT/FOAT cannot do without predictive modeling (PM), 2) carry out PM to understand the physics of failure; 3) predict, using the results of the carried out ALT/FOAT and PM, and the PDfR modeling, the probability of failure in the field (operation, mission); 4) carry out sensitivity analyses to establish the acceptable probability of failure; 5) revisit, review and revise the existing QT practices, procedures, and specifications; and 6) develop and widely implement the probabilistic design for reliability (PDfR) concept, methodologies and algorithms, considering that the probability of failure is never zero, but could be predicted and, if necessary, minimized, controlled, specified and even maintained at an acceptable level. Prognostication and health monitoring (PHM) approaches and techniques could be very helpful at all the stages of the design, manufacturing and operation of the electronic or photonic system, with or without considering the role of the human factor.