A Quantitative Analysis of Semiconductor Device Failure Rates as Graphically Indicated in Military Handbook 217

A graphical presentation of semiconductor device failure rates is made in Figs. 13B and 14B of Mil-Hdbk-217 (see Figs. 1 and 2). From this presentation, Equations may be derived which indicate interesting properties, to failure physicists, device engineers, and equipment designers. On the basis of the equations it may be concluded that: (1) extrapolating room temperature failure rates from failure rates of devices stored at elevated temperatures is not likely to be meaningful; (2) there is a definite relationship between storage failure rate and failure rate in actual use (in the temperature range of interest); (3) the storage failure rate is large enough at normal storage temperatures so that, if semiconductor device failure rates influence the reliability of equipment in which they are used, they will contribute significantly to the finite storage life of the equipment (another way of expressing the last statement is that a manufacturer with a large storage inventory of semiconductors will find a significant decrease in the percentage of usable devices with time);(4) there are some instances (as delineated earlier by equations), when increasing the number of semiconductor devices and dividing the load proportionately improves reliability, and there are other cases when it does not. While the analysis makes no claim as to the validity or accuracy of Figs. 1 and 2, the mathematics permits statements about conditions necessary to confirm the data.