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Quality improvement through quality progress
538
World Abstracts on Microelectronics and Reliability
overall construction of a package and subsequent electrical testing is simple.
Applications of the scanning electron microscope EBIC mode to semiconductor device evaluation and failure analysis. R. H. SORENSEN, I. THOMSON and L. ADAMS. Microelectron. J, 11, (1) 19 (1980). This paper shows how the Electron Beam Induced Current (EBIC) mode of operation finds routine application in the failure analysis and evaluation of semiconductor devices for space application. Most of the previously published work on EBIC has been of a theoretical nature and has concentrated on the quantitative aspect such as the measurement of minority carrier lifetime. The EBIC mode, however, also lends itself to the qualitative evaluation and analysis of comparatively complex semiconductor devices and in particular the study of diffusion spikes and similar effects. The routine application of the EBIC mode to practical device analysis is described and illustrated by case histories of device problems. Improvements in experimental techniques are proposed based on the work presented. R & M of socketed ICs. J. M. ERICKSON, W. D. TOWNES and J. F. LEARY. IEEE Trans. Reliab. R-28, (5) 338 (December 1979). This study shows that sockets can be reliable enough in a relatively benign environment for the short-term. Criteria for failure-free performance include l) operation in a controlled, non-vibration environment, 2) gold-plated, machined sockets, 3) either gold or tin-plated IC leads. Accelerated testing is required to estimate longterm reliability. Numerous federal and commercial systems use socketed integrated circuits (ICs) satisfactorily. Maintainability of circuit boards, ease of equipment upgrading, and simplifying transition from development to production are some of the advantages of sockets.
Reliable thyristors and triacs in TO-220 plastic packages. P. Blunt. Electron. Components Appl. 2, (1) 53 (November 1979). No devices make more demands on power semiconductor fabrication techniques than thyristors and triacs. Their construction and packaging must withstand rapid, large fluctuations of temperature and provide effective insulation to enable high voltages to be handled by small structures. They must have stable leakage characteristics to prevent false triggering. These requirements have not been well satisfied by traditional technology. However, eutectic bonding and diffusion isolation have now overcome the conformance and reliability barriers set by the usual softsoldered TO-220 thyristor and triac construction methods. Power-control equipment using TO-220 devices based on the new technology is setting new standards for reliability. This article gives the reasons for the design changes, and justifies them with intermediate results from continuing, long-term life testing.
Non-destructive examination of eutectic die-bonds in high power silicon devices using air-coupled ultrasound. R. L. CROCKER. Proc. Internepcon UK '79, p. 231, Brighton, (16-18 October 1979). High frequency ultrasound is being used to examine the eutectic bond between silicon devices and their heat sinks. Conventional ultrasonic techniques are not feasible in this application and an air-coupled system is being developed. In order to predict the effect of voids in the bond line of the devices on the transmission of sonic energy, a mathematical model is being developed. This combines frequency dependent transmission and reflection coefficients of the various materials in the system and will permit examination of voids of differing types and sizes. The aim of the work is to produce an on-line bond test station to be positioned as close to the bonding unit as possible, with the capability of testing one device per second.
3. CIRCUIT AND SYSTEMS RELIABILITY, MAINTENANCE A N D R E D U N D A N C Y Quality improvement through quality progress, p. 22 (November 1979). How one firm took steps to assure uniform quality of its LED Transfer Molding.
The efficient manipulation of Boolean logic. JAMES M. CARGAL. Proc. IEEE Reliab. Syrup. p. 361 Washington D.C. (23-25 January 1979). An important technique of reliability engineering is fault tree analysis, which essentially consists of logically diagramming, then analyzing the events that can lead within some well-defined system to a particular well-defined event, the "top event." In the analysis portion of the task, there is an algebra, in fact a Boolean algebra, which is associated with the events within the system. The body of this paper concerns the algebraic manipulation of these events. It is the intent here to make this manipulation as simple as possible. The ring sum operation discussed (also known as the symmetric difference operation) is very familiar to algebraists. However, there is little evidence of much algebraic impact or logic impact in reliability engineering. In fault tree analysis, the "algebra" is the algebra associated with the tree. This view-point will be presented here. Eventually, rather than the algebra associated with a tree, it might be advantageous to consider what technique of analysis is best suited to the algebra associated with the system. At the end, deeper "non-trivial" possibilities will be touched upon. It is assumed that the reader is familiar with naive set theory and with elementary Boolean algebra. It is preferred that the reader be familiar with fault tree analysis as well. Many proofs will be skipped.
Cost optimization subject to availability constraints. A. WIL-
LIAM KRATZKE and JOLEROY GAUGER. Proc. IEEE Reliab. Syrup. p. 73, Washington, D.C. (23-25 January 1979). The Operation and Support part of Life Cycle Cost planning during the conceptual phase of a program can be regarded as an exercise in system optimization. We propose a model for availability that admits of MTBF decay and accordingly let LCC be dependent on that degradation. Optimization is based on optimal control theory and a closed loop control function is derived.
Treatment of dependencies in reliability analyses. G. E. INGRAM and JON G. ELERATH. Proc. IEEE Reliab. Syrup. p. 99, Washington, D.C. (23-25 January 1979). This paper presents a method for the evaluation of dependencies in discrete reliability models. The theoretical basis for evaluation and the computer code PROBCALC which makes this method tractable for any system are presented. Examples of model dependencies are taken from analyses of Shutdown Heat Removal Systems in loop type Breeder Reactors. The general technique and the use of PROBCALC are both illustrated by application to an example Shutdown Heat Removal System.
A reliability growth management approach. DAVID J. SIMKINS. Proc. IEEE Reliab. Syrup. p. 356, Washington, D.C. (23-25 January 1979). This paper describes a real-time reliability measurement, tracking, and control approach that can be implemented during development of a major weapon system. This approach provides real-time visibility and accountability to quickly check for nonconformance to reliability requirements. It allows a multitier growth track-
World Abstracts on Microelectronics and Reliability ing (equipment, subsystem, and system) and permits multitier confidence band construction. Finally, it incorporates data from equipments that develop at different rates and over different time periods and accounts for product degradation. Improving system safety through risk assessment. J. B. FUSSELL,D. P. WAGNER,J. S. ARENDT,J. J. ROONEY,W. K. CROWLEY, D. J. CAMPBELL, Prec. IEEE Reliab. Syrup. p. 160, Washington, D.C. (23-25 January 1979). This paper outlines a computer aided methodology for determining the relative contributions of various subsystems and components to the total risk associated with an engineered' system. Major contributors to system risk are identified through comparison of an expected frequency density function with an established risk criterion. The results from these analyses are useful for directing efforts for improving system safety and performance. An analysis of uranium hexafluoride handling risk at a gaseous diffusion uranium enrichment plant using the computer program EXCON is briefly described. This work was performed by JBF Associates, Inc. for Union Carbide Corporation--Nuclear Division under Contract Number 19X-55443V. Reliability described by belief functions. GLENN SHAFERand A. M. BREXPOHL.Proc. IEEE Reliab. Syrup. p. 23, Washington, D.C. (23-25 January 1979). How can we summarize the evidence concerning the reliability of a certain piece of equipment under certain conditions? The ideal would be to state the equipment's chance of success--i.e., the frequency with which similar equipment would perform satisfactorily in repeated trials under similar conditions. But usually we do not know this chance, and we must state instead our degree of belief that the equipment will perform satisfactorily. Typically, this degree of belief is based on a variety of evidence, much of which requires subjective evaluation. The purpose of this paper is to illustrate how the combination of such evidence, which is so important in reliability practice, can be carried out using belief functions. A computerized LCC/ORLA methodology. J. T. HENDERSON, P.E. Prec. IEEE Reliab. Symp. p. 51, Washington, D.C. (23-25 January 1979). This paper describes the effort expended by Sandia Laboratories in developing CDC6600 computer programs for Optimum Repair Level Analysis (ORLA) and Life-Cycle Cost (LCC) analysis. Investigation of the three repair-level strategies referenced in AFLCM/AFSCM 800-4 (base discard of subassemblies, base repair of subassemblies, and depot repair of subassemblies) was expanded to include an additional three repair-level strategies (base discard of complete assemblies and, upon shipment of complete assemblies to the depot, depot repair of assemblies by subassembly repair, and depot repair of assemblies by subassembly discard). The expanded ORLA was used directly in an LCC model that was procedurally altered to accommodate the ORLA input data. Available from the LCC computer run was an LCC value corresponding to the strategy chosen from the ORLA.
539
is provided of costs used in evaluating effectiveness of regulations and how product assurance management can improve cooperation and change in regulatory areas. Considerations in R & M program 6plimization. G. W. WINDOLPH. Prec. IEEE Reliab. Symp. p. 1, Washington, D.C. (23-25 January 1"979). Experience on recent helicopter development programs, such as the Army CH-47D Chinook program, suggests effective ways to define and implement program efforts. In those programs the tradeoffs and timing between simple analyses and full-blown formal ones, including logistics support analyses, were encountered and resolved. The reliability and maintainability engineers became effective subsystems integrators through the timely performance of their analyses and the use of simple mockup techniques to get their points a/:ross. In short, the proper tasks and talents can be identified before a program begins, and the proper motivational forces can be exerted to assure a successful assurancedisciplines program. The customer and the contractor share the responsibility for making the program effective. When it is done properly, the reliability and maintainability engineers need not take the back seat to anyone. Rather, they share a large seat with the weights, stress, aerodynamics, and other technology engineers, all of whom are cultists relative to their unique interests and are there to help the designer get his job done right. Markov analyses of nuclear plant failure dependencies. OMER GOKCEK,IGOR BAZOVSt:Y,SR. and GARY L. CRELLIN: Proc. IEEE Reliab. Syrup. p. 104, Washington, D.C. (23-25 January 1979). This paper uses Markovian techniques which have been developed at General Electric Company, Advanced Reactor Systems Department to analyze ',he effect of dependencies on reliability and availability of plant shutdown and shutdown heat removal systems. Flow graph analysis is employed to obtain dynamic functional equations for the reliability and availability of such systems. The application of Mason's rule in Laplace transform domain analysis simplifies the computational procedure. AN/UYK-20 computer production reliability test. JAMESG. KZALEY. Proc. IEEE Reliab. Syrup. p. 128, Washington, D.C. (23-25 January 1979). Successful completion of a MIL-STD-781, Test Plan XXIX, Reliability Test program is dependent upon: (a) design integrity; (b) quality of workmanship and components; (c) an effective pre-TPXXIX screen test program; (d) a timely and effective corrective action system and (e) procedural controls. Functional and environmental operating margins must be established through an effective pre TPXXIX test program to further enhance inherent reliability, minimize consumer risk and yet allow an acceptable level of producer jeopardy.
Limits of models in reliability engineering. Prof. Dr. G. ALMASSY,Prec. 1EEE Reliab. Syrup. p. 364, Washington, D.C. (23-25 January 1979). A short survey of models used in the reliability engineering.
Sample size for selecting most reliable of K normal (Iognormal) populations. TERRY L. KING, CHARLES E. ANTLE and RUSSELLF. KAPPENMAN.IEEE Trans. Reliab. R-28, (1) 14 (April 1979). An experimenter wishes to select the most reliable of K s-normal (or lognormal) populations. If he samples n items from each of the K populations, then how large should n be in order that he will have a desired level for the probability of correct selection? This paper gives tables which answer this sample-size question.
Regulatory cost management and product assurance. HARVEY E. SCHOCK,JR. Prec. IEEE Reliab. Syrup. p. 13, Washington, D.C. (23-25 January 1979). Government regulations often impose problems in product assurance areas for producers and regulators. The paper reviews some of these problems and impact of latest government instructions for improvements in existing and future regulations. A review
Update of Lapp--Powers fault-tree synthesis algorithm. STEVENA. LAPP and GARY J. POWERS. IEEE Trans. Reliab. R-28, (1) 12 (April 1979). The original paper used an example about which there has been considerable discussion. This note shows that the original analysis was correct, and that sematic difficulties are difficult to avoid.
World Abstracts on Microelectronics and Reliability
overall construction of a package and subsequent electrical testing is simple.
Applications of the scanning electron microscope EBIC mode to semiconductor device evaluation and failure analysis. R. H. SORENSEN, I. THOMSON and L. ADAMS. Microelectron. J, 11, (1) 19 (1980). This paper shows how the Electron Beam Induced Current (EBIC) mode of operation finds routine application in the failure analysis and evaluation of semiconductor devices for space application. Most of the previously published work on EBIC has been of a theoretical nature and has concentrated on the quantitative aspect such as the measurement of minority carrier lifetime. The EBIC mode, however, also lends itself to the qualitative evaluation and analysis of comparatively complex semiconductor devices and in particular the study of diffusion spikes and similar effects. The routine application of the EBIC mode to practical device analysis is described and illustrated by case histories of device problems. Improvements in experimental techniques are proposed based on the work presented. R & M of socketed ICs. J. M. ERICKSON, W. D. TOWNES and J. F. LEARY. IEEE Trans. Reliab. R-28, (5) 338 (December 1979). This study shows that sockets can be reliable enough in a relatively benign environment for the short-term. Criteria for failure-free performance include l) operation in a controlled, non-vibration environment, 2) gold-plated, machined sockets, 3) either gold or tin-plated IC leads. Accelerated testing is required to estimate longterm reliability. Numerous federal and commercial systems use socketed integrated circuits (ICs) satisfactorily. Maintainability of circuit boards, ease of equipment upgrading, and simplifying transition from development to production are some of the advantages of sockets.
Reliable thyristors and triacs in TO-220 plastic packages. P. Blunt. Electron. Components Appl. 2, (1) 53 (November 1979). No devices make more demands on power semiconductor fabrication techniques than thyristors and triacs. Their construction and packaging must withstand rapid, large fluctuations of temperature and provide effective insulation to enable high voltages to be handled by small structures. They must have stable leakage characteristics to prevent false triggering. These requirements have not been well satisfied by traditional technology. However, eutectic bonding and diffusion isolation have now overcome the conformance and reliability barriers set by the usual softsoldered TO-220 thyristor and triac construction methods. Power-control equipment using TO-220 devices based on the new technology is setting new standards for reliability. This article gives the reasons for the design changes, and justifies them with intermediate results from continuing, long-term life testing.
Non-destructive examination of eutectic die-bonds in high power silicon devices using air-coupled ultrasound. R. L. CROCKER. Proc. Internepcon UK '79, p. 231, Brighton, (16-18 October 1979). High frequency ultrasound is being used to examine the eutectic bond between silicon devices and their heat sinks. Conventional ultrasonic techniques are not feasible in this application and an air-coupled system is being developed. In order to predict the effect of voids in the bond line of the devices on the transmission of sonic energy, a mathematical model is being developed. This combines frequency dependent transmission and reflection coefficients of the various materials in the system and will permit examination of voids of differing types and sizes. The aim of the work is to produce an on-line bond test station to be positioned as close to the bonding unit as possible, with the capability of testing one device per second.
3. CIRCUIT AND SYSTEMS RELIABILITY, MAINTENANCE A N D R E D U N D A N C Y Quality improvement through quality progress, p. 22 (November 1979). How one firm took steps to assure uniform quality of its LED Transfer Molding.
The efficient manipulation of Boolean logic. JAMES M. CARGAL. Proc. IEEE Reliab. Syrup. p. 361 Washington D.C. (23-25 January 1979). An important technique of reliability engineering is fault tree analysis, which essentially consists of logically diagramming, then analyzing the events that can lead within some well-defined system to a particular well-defined event, the "top event." In the analysis portion of the task, there is an algebra, in fact a Boolean algebra, which is associated with the events within the system. The body of this paper concerns the algebraic manipulation of these events. It is the intent here to make this manipulation as simple as possible. The ring sum operation discussed (also known as the symmetric difference operation) is very familiar to algebraists. However, there is little evidence of much algebraic impact or logic impact in reliability engineering. In fault tree analysis, the "algebra" is the algebra associated with the tree. This view-point will be presented here. Eventually, rather than the algebra associated with a tree, it might be advantageous to consider what technique of analysis is best suited to the algebra associated with the system. At the end, deeper "non-trivial" possibilities will be touched upon. It is assumed that the reader is familiar with naive set theory and with elementary Boolean algebra. It is preferred that the reader be familiar with fault tree analysis as well. Many proofs will be skipped.
Cost optimization subject to availability constraints. A. WIL-
LIAM KRATZKE and JOLEROY GAUGER. Proc. IEEE Reliab. Syrup. p. 73, Washington, D.C. (23-25 January 1979). The Operation and Support part of Life Cycle Cost planning during the conceptual phase of a program can be regarded as an exercise in system optimization. We propose a model for availability that admits of MTBF decay and accordingly let LCC be dependent on that degradation. Optimization is based on optimal control theory and a closed loop control function is derived.
Treatment of dependencies in reliability analyses. G. E. INGRAM and JON G. ELERATH. Proc. IEEE Reliab. Syrup. p. 99, Washington, D.C. (23-25 January 1979). This paper presents a method for the evaluation of dependencies in discrete reliability models. The theoretical basis for evaluation and the computer code PROBCALC which makes this method tractable for any system are presented. Examples of model dependencies are taken from analyses of Shutdown Heat Removal Systems in loop type Breeder Reactors. The general technique and the use of PROBCALC are both illustrated by application to an example Shutdown Heat Removal System.
A reliability growth management approach. DAVID J. SIMKINS. Proc. IEEE Reliab. Syrup. p. 356, Washington, D.C. (23-25 January 1979). This paper describes a real-time reliability measurement, tracking, and control approach that can be implemented during development of a major weapon system. This approach provides real-time visibility and accountability to quickly check for nonconformance to reliability requirements. It allows a multitier growth track-
World Abstracts on Microelectronics and Reliability ing (equipment, subsystem, and system) and permits multitier confidence band construction. Finally, it incorporates data from equipments that develop at different rates and over different time periods and accounts for product degradation. Improving system safety through risk assessment. J. B. FUSSELL,D. P. WAGNER,J. S. ARENDT,J. J. ROONEY,W. K. CROWLEY, D. J. CAMPBELL, Prec. IEEE Reliab. Syrup. p. 160, Washington, D.C. (23-25 January 1979). This paper outlines a computer aided methodology for determining the relative contributions of various subsystems and components to the total risk associated with an engineered' system. Major contributors to system risk are identified through comparison of an expected frequency density function with an established risk criterion. The results from these analyses are useful for directing efforts for improving system safety and performance. An analysis of uranium hexafluoride handling risk at a gaseous diffusion uranium enrichment plant using the computer program EXCON is briefly described. This work was performed by JBF Associates, Inc. for Union Carbide Corporation--Nuclear Division under Contract Number 19X-55443V. Reliability described by belief functions. GLENN SHAFERand A. M. BREXPOHL.Proc. IEEE Reliab. Syrup. p. 23, Washington, D.C. (23-25 January 1979). How can we summarize the evidence concerning the reliability of a certain piece of equipment under certain conditions? The ideal would be to state the equipment's chance of success--i.e., the frequency with which similar equipment would perform satisfactorily in repeated trials under similar conditions. But usually we do not know this chance, and we must state instead our degree of belief that the equipment will perform satisfactorily. Typically, this degree of belief is based on a variety of evidence, much of which requires subjective evaluation. The purpose of this paper is to illustrate how the combination of such evidence, which is so important in reliability practice, can be carried out using belief functions. A computerized LCC/ORLA methodology. J. T. HENDERSON, P.E. Prec. IEEE Reliab. Symp. p. 51, Washington, D.C. (23-25 January 1979). This paper describes the effort expended by Sandia Laboratories in developing CDC6600 computer programs for Optimum Repair Level Analysis (ORLA) and Life-Cycle Cost (LCC) analysis. Investigation of the three repair-level strategies referenced in AFLCM/AFSCM 800-4 (base discard of subassemblies, base repair of subassemblies, and depot repair of subassemblies) was expanded to include an additional three repair-level strategies (base discard of complete assemblies and, upon shipment of complete assemblies to the depot, depot repair of assemblies by subassembly repair, and depot repair of assemblies by subassembly discard). The expanded ORLA was used directly in an LCC model that was procedurally altered to accommodate the ORLA input data. Available from the LCC computer run was an LCC value corresponding to the strategy chosen from the ORLA.
539
is provided of costs used in evaluating effectiveness of regulations and how product assurance management can improve cooperation and change in regulatory areas. Considerations in R & M program 6plimization. G. W. WINDOLPH. Prec. IEEE Reliab. Symp. p. 1, Washington, D.C. (23-25 January 1"979). Experience on recent helicopter development programs, such as the Army CH-47D Chinook program, suggests effective ways to define and implement program efforts. In those programs the tradeoffs and timing between simple analyses and full-blown formal ones, including logistics support analyses, were encountered and resolved. The reliability and maintainability engineers became effective subsystems integrators through the timely performance of their analyses and the use of simple mockup techniques to get their points a/:ross. In short, the proper tasks and talents can be identified before a program begins, and the proper motivational forces can be exerted to assure a successful assurancedisciplines program. The customer and the contractor share the responsibility for making the program effective. When it is done properly, the reliability and maintainability engineers need not take the back seat to anyone. Rather, they share a large seat with the weights, stress, aerodynamics, and other technology engineers, all of whom are cultists relative to their unique interests and are there to help the designer get his job done right. Markov analyses of nuclear plant failure dependencies. OMER GOKCEK,IGOR BAZOVSt:Y,SR. and GARY L. CRELLIN: Proc. IEEE Reliab. Syrup. p. 104, Washington, D.C. (23-25 January 1979). This paper uses Markovian techniques which have been developed at General Electric Company, Advanced Reactor Systems Department to analyze ',he effect of dependencies on reliability and availability of plant shutdown and shutdown heat removal systems. Flow graph analysis is employed to obtain dynamic functional equations for the reliability and availability of such systems. The application of Mason's rule in Laplace transform domain analysis simplifies the computational procedure. AN/UYK-20 computer production reliability test. JAMESG. KZALEY. Proc. IEEE Reliab. Syrup. p. 128, Washington, D.C. (23-25 January 1979). Successful completion of a MIL-STD-781, Test Plan XXIX, Reliability Test program is dependent upon: (a) design integrity; (b) quality of workmanship and components; (c) an effective pre-TPXXIX screen test program; (d) a timely and effective corrective action system and (e) procedural controls. Functional and environmental operating margins must be established through an effective pre TPXXIX test program to further enhance inherent reliability, minimize consumer risk and yet allow an acceptable level of producer jeopardy.
Limits of models in reliability engineering. Prof. Dr. G. ALMASSY,Prec. 1EEE Reliab. Syrup. p. 364, Washington, D.C. (23-25 January 1979). A short survey of models used in the reliability engineering.
Sample size for selecting most reliable of K normal (Iognormal) populations. TERRY L. KING, CHARLES E. ANTLE and RUSSELLF. KAPPENMAN.IEEE Trans. Reliab. R-28, (1) 14 (April 1979). An experimenter wishes to select the most reliable of K s-normal (or lognormal) populations. If he samples n items from each of the K populations, then how large should n be in order that he will have a desired level for the probability of correct selection? This paper gives tables which answer this sample-size question.
Regulatory cost management and product assurance. HARVEY E. SCHOCK,JR. Prec. IEEE Reliab. Syrup. p. 13, Washington, D.C. (23-25 January 1979). Government regulations often impose problems in product assurance areas for producers and regulators. The paper reviews some of these problems and impact of latest government instructions for improvements in existing and future regulations. A review
Update of Lapp--Powers fault-tree synthesis algorithm. STEVENA. LAPP and GARY J. POWERS. IEEE Trans. Reliab. R-28, (1) 12 (April 1979). The original paper used an example about which there has been considerable discussion. This note shows that the original analysis was correct, and that sematic difficulties are difficult to avoid.