Integrated circuit reliability

ABSTRACTS ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y

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Zener a n d a v a l a n c h e breakdown in silicon alloyed p-n junctions--II. Effect of temperature on the reverse characteristics a n d criteria for distinguishing between the two breakdown m e c h a n i s m s . M. SINGH TYACl, Solid-St. Electron. 11 (1968), p. 117. The effect of temperature on the reverse current and breakdown voltage of silicon p-n junctions for a wide range of breakdown voltages has been investigated and the criteria for differentiating the Zener breakdown from avalanche breakdown have been presented. Narrow p-n junctions with soft characteristics have a temperature insensitive reverse current, contributed by internal field emission and show a negative temperature coefficient ~ of breakdown voltage which is determined up to a large extent by the available phonon density present in tunnelling transitions. Wider junctions with I/'B> 13 V show a highly temperature sensitive current and a positive value of ~, which is in good agreement with the avalanche multiplication theory. For values of Vs from 3.5 to 13 V there is a transition region from Zener to avalanche type of breakdown in which the temperature dependence of the reverse characteristics is complex and cannot be accounted by a single mechanism. Apart from the temperature dependence of breakdown voltage such properties as generation of microplasma noise, dependence of breakdown voltage on impurity concentration, space-charge layer width and maximum field strength at breakdown have been found to show distinct differences between Zener and avalanche regions and give a further support to the conclusions reached from the temperature studies. CIRCUIT AND SYSTEMS RELIABILITY, MAINTENANCE, REDUNDANCY Major causes of equipment unreliability. J. PATERSON,Radio Electron. Engr, October (1967), p. 247. Defect statistics on guided weapons and other equipment clearly indicate that the more unusual components and the "special to project" innovations show the highest failure rates. Electromechanical components are examples and such failures are emphasized in guided weapons as the total running time may be a few hours with only a few minutes in flight. This paper shows that since the design and shape of most electrical/electronic components is primarily to facilitate their functions and ease of production, a large variety of shapes and sizes for different types of components is a major problem in equipment design. It is suggested that improved customer/vendor relations and national standardization of new styles of components might help to ease the situation. D y n a m i c m e c h a n i s m reliability by Monte Carlo methods. F. R. VAN WACNER, 8th .,inn. ASQC West Coast Reliab. Syrup., February 18 (1967), p. 71. The Monte Carlo method provides a way of evaluating a complex reliability formula which would defy ordinary analytic approaches in all but a handful of trivial cases. The formula itself, derived by a technique called conditional convolution, gives the exact probability that a randomly constructed mechanism can perform a given task N times with R or fewer failures. Two computer programs, one a general-purpose Monte Carlo simulator, have been developed to handle the computations. They have been applied many times by IBM engineers to designreliability problems with proven success. Integrated circuit reliability. JOSEPH FLOOD and K. R. MACKF.NZI~,Electron. Equip. News, August (1967), p. 24. Reliability performance of i.c.s, is constantly being compared to that of transistors in similar applications. A recent ARINC report surveys five operational computer systems and demonstrates that the rate of replacement of i.c.s, is no higher than that of transistors in similar digital applications. Equipment reliability has been improved by a factor comparable to the quotient of the original number of transistors divided by the replacing number of i.c.s. Design for maintainability with particular reference to domestic radio and television receivers. D. W. HSIGHTMAN,Radio Electron. Engr, October (1967), p. 195. The main theme of this paper is that of designing good maintainability into a product from the viewpoints of (a) basic component reliability, (b) readily accessible test/monitoring points and (c) ready access and speedy changing of components or modules in cases of failure. The coming of colour television, with its greater complexity, emphasizes the need for attention to these points. Aspects of using infrared for electronic circuit diagnosis. RUTH A. HERMAN. Mater. Eval., September (1967), p. 201. The validity of infrared radiation as a checkout parameter for the diagnosis