Physics of Failure in Commercialand

WHAT are the major differences between Military and Commercial reliability? The two outstanding differences noted since reliability programs were instituted on our commercial products are that 1. in the commercial field the emphasis on economic justification is greater, and 2. the spread in quality of components being sold to the same specifications is much greater for the commercial market. This paper will discuss the interrelationship of these two aspects of commercial reliability. The greatest gains have resulted in reduced costs and improved reliability through "physics-of-failure" studies. The major reason for this is the misconception among people charged with the responsibility for selecting the parts used in an equipment that there is no difference between component piece parts that are purchased to the same specification. The goal of the commercial physics-of-failure program is to find the significant difference between parts which satisfy the basic specification, and to determine the optimum component for use in the particular application. Examples of diode, resistor, and capacitor problems solved using the same general technique, will be discussed, and the reasons for, and the consequences of, the differences highlighted. The choice of the phrase "physics of failure" is unfortunate because it gives the connotation that the major area of effort is concerned with the autopsies on failed components. The same techniques can and have been applied to curative and preventative areas as well (screening tests and vendor selection). The applications of physics to screening of components and vendor selection will be discussed.