HALT, FOAT and their role in making a viable device into a reliable product

Despite all the today´s effort, devices and systems that underwent the highly popular highly-accelerated-life-testing (HALT), passed the existing qualification tests (QT) and survived the burn-in testing (BIT), often fail in the field. Are these tests, specifications and practices adequate? If not, could they be improved to an extent that for a product that passed the QT and survived the appropriate burn-in tests (BIT), there is a quantifiable and sustainable way to assure that it will perform satisfactorily, in a failure-free fashion, in the field? Do industries and particularly aerospace electronic and photonic industries need new approaches to qualify their products? This is especially important when high reliability is a must and when the performance of various non-electronic systems depends heavily on the electronic and photonic equipment reliability. It has been recently suggested [1-4] that probabilistic design for reliability (PDfR) concept, based on the highly focused and cost-effective failure-oriented-accelerated-testing (FOAT) and effective and physically meaningful predictive modeling (PM), might be an appropriate way to dramatically improve the state-of-the-art in the field. Whether one admits that or not, reliability is conceived at the design stage, and should be addressed, first of all, at this stage. Then a “genetically healthy” product has a good chance to be created and various prognostics-and-health-managing (PHM) methods and techniques will have a much better chance to succeed at the operation stage. Since nothing and nobody is perfect, and the difference between a highly reliable and an insufficiently reliable product is “merely” in the level of the probability of its failure, applied probability and probabilistic risk analysis (PRA) should be used to assess and assure the adequate probability of the field failure. If one is able to quantify this probability and to assure that it is adequate (actually, suffici- ntly low), then there is a good reason to believe (“principle of practical confidence”) that a failure-free operation will be likely. A highly focused and highly cost effective FOAT, which is, along with effective and physically meaningful predictive modeling (PM), is the heart of the PDfR concept, should be designed, conducted and properly interpreted in addition to and, in some cases (e.g., for new products) even instead of HALT. FOAT should be geared to a particular simple, easy-to-use and physically meaningful predictive accelerated test model that enables the reliability physicist to bridge the gap between what he/she observes as the result of FOAT and what will most likely take place in actual operation.