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Reliability of plastic-encapsulated integrated circuits in moisture environments
World Abstracts on Microelectronics and Reliability positions. The technique of using changes in metal stripe resistance to predict the time of failure was evaluated.
Bond-integrity testing of sapphire chips mounted with eutectic preforms. THOMASJ. FAITH, JR. and ROBERT S. IRVEN. IEEE Trans. Components Hybrids Mfo Technol. CHMT-7 (2), 189 (1984). The 3000 5000 A polysilicon film deposited on the back surface of a sapphire wafer during the polysilicongate deposition process is shown to. provide a satisfactory bonding layer for eutectic mounting of silicon-on-sapphire (SOS) chips to gold-plated packages using Au-Si eutectic preforms, provided that the back-surface polysilicon film is maintained in the undoped state during subsequent wafer processing. N+-doped polysilicon films provide less satisfactory bonding surfaces, passing all M1L-STD-883B environmental tests, but failing more severe tests which the undoped polysilicon films are shown to pass. Bare sapphire is shown to provide a surprisingly good bonding interface with Au-Si eutectic preforms giving MIL-STD-883B test results equivalent to the undoped polysilicon films and destructive-test results which were comparable to the n ÷ polysilicon films.
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Software reliability analysis models. MITSURU OHBA. IBM J. Res. Dev. 28 (4), 428 (1984). This paper discusses improvements to conventional software reliability analysis models by making the assumptions on which they are based more realistic. In an actual project environment, sometimes no more information is available than reliability data obtained from a test report. The models described here are designed to resolve the problems caused by this constraint on the availability of reliability data. By utilizing the technical knowledge about a program, a test, and test data, we can select an appropriate software reliability analysis model for accurate quality assessment. The delayed S-shaped growth model, the inflection S-shaped model, and the hyperexponcntial model are proposed. A logarithmic reliability-growth model for single-mission systems. J. M. F1NKELSTEIN. IEEE Trans. Reliab. R-32 (5), 508 (1983). A logarithmic growth model for the reliability of single-mission systems is proposed, and estimators for its two parameters are analyzed. Reliability growth produced by a 'test, analyze, and fix' (TAAF) program has a discrete measure of size, viz, the number of tests. The proposed growth model is similar to the popular nonhomogeneous Poisson process (Duane) growth models, and uses the discrete testnumber variable in place of test time. Analysis of simulation results shows that the continuous analog estimators arc superior to the least squares estimators. Both sets of estimators are s-consistent for a large number of tests, have acceptably small variability, and are easy to calculate. The continuous analog estimators have less variability than the least squares estimators and underestimate reliability, while the least squares estimators overestimate reliability. The application of the model, with the continuous analog estimators, to planning and monitoring the reliability development test program for a single-mission system is described. Adaptive robust estimation based on a family of generalized exponential power distributions. GEORGE E. CROWDER and ALBERT H. MOORE. IEEE Trans. Reliab. R-32 (5), 488 (1983). This paper suggests using the family of exponential power (EP) distributions to model data which are believed (a priori) to be essentially symmetric but where the usual assumptions of s-normality is unwarranted. Four estimation procedures are proposed for the parameters of the distribution. Two procedures are based on variations of the method of maximum likelihood (ML) while the other two use the method of MR 25:3-L
583
Reliability of plastic-encapsulated integrated circuits in moisture environments. L. GALLACEand M. ROSENFIELD.RCA Rev. 45, 249 (1984). An overview of the factors affecting the reliability of plastic-encapsulated ICs in moisture environments is presented. Particular attention is given to the moisture-related failure mechanism EMA (electrolytic metal attack). The package design and process steps and techniques developed at RCA (through identification of the proper analytical models, thorough engineering programs, and by the statistical design of experiments) are detailed. Particular attention was paid to eliminating chlorides and their sources. The nature and state of on-going plastic-package moisture-resistance programs and future expectations are described. Current problems in v.i.s.i, testing and testability. P. K. LALA. Radio Electron. Engr 54 (10), 415 (1984). This paper presents the basic concepts in testing, beginning with fault-models, and summarizes the major contributions to the design of testable logic. It identifies some of the current problems in v.l.s.i, testing and testability which need further investigation.
MAINTENANCE
AND
REDUNDANCY
moments to estimate the shape parameter but employ ML to estimate the location and scale parameters of the model. A Monte Carlo analysis compares the mean square errors of the estimators of the location and scale parameters of the model. Sample sizes 4(4)28 were drawn 2000 times from five symmetric probability distributions. A minimax criterion was used to evaluate each of the estimators. Comparison with adaptive and nonadaptive estimates of location and scale parameters show that the new procedure provides: (1) good estimates of scale and location parameters, and (2) a complete probability model for the data.
Testing ultra high speed devices. PETER H. SINGER. Semiconductor Int. 48 (September 1984). Many of today's stateof-the-art MOS and bipolar devices operate at speeds approaching the limits of most standard ATE. New GaAs and VHSIC technologies are also pushing the limits of high speed testing. Resilient concurrency control in distributed database systems. BHARAT BHARGAWA. IEEE Trans. Reliab. R-32 (5), 437 (1983). This paper presents the resiliency features of the optimistic approach to concurrency control and demonstrates how it lends itself to a design of a reliable distributed database system. The validation of concurrency control, integrity control, and atomicity control has been integrated. This integration provides a high degree of concurrency and continuity of operations in spite of failures of transactions, processors, and communication system. Analytical study of the pointwise availability of a parallel redundant 2-out-of-N :F system under head-of-line repair echelon. P. P. GUPTA and SUNIL KUMAR MITTAL. QR J. 55 (May 1984). The paper presents a multicomponent repairable system with two classes (A, B) of components. Class A consists of two identical components in parallel redundancy whereas B involves N-non identical components with l-outo f - N : D and 2-out-of-N:F arrangements. The reliability parameters are derived for the exponential failure and general repair time distributions under FIFO policy for repair. Particular cases are explained. The behaviour of time dependent availability of the system has been evaluated in a numerical example by inverting the L.T. An accurate probability-of-failure calculation method. A. HARBITZ. IEEE Trans. Reliab. R-32 (5), 458 (1983). Based on rules of transformation of stochastic variables, a general and
Bond-integrity testing of sapphire chips mounted with eutectic preforms. THOMASJ. FAITH, JR. and ROBERT S. IRVEN. IEEE Trans. Components Hybrids Mfo Technol. CHMT-7 (2), 189 (1984). The 3000 5000 A polysilicon film deposited on the back surface of a sapphire wafer during the polysilicongate deposition process is shown to. provide a satisfactory bonding layer for eutectic mounting of silicon-on-sapphire (SOS) chips to gold-plated packages using Au-Si eutectic preforms, provided that the back-surface polysilicon film is maintained in the undoped state during subsequent wafer processing. N+-doped polysilicon films provide less satisfactory bonding surfaces, passing all M1L-STD-883B environmental tests, but failing more severe tests which the undoped polysilicon films are shown to pass. Bare sapphire is shown to provide a surprisingly good bonding interface with Au-Si eutectic preforms giving MIL-STD-883B test results equivalent to the undoped polysilicon films and destructive-test results which were comparable to the n ÷ polysilicon films.
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Software reliability analysis models. MITSURU OHBA. IBM J. Res. Dev. 28 (4), 428 (1984). This paper discusses improvements to conventional software reliability analysis models by making the assumptions on which they are based more realistic. In an actual project environment, sometimes no more information is available than reliability data obtained from a test report. The models described here are designed to resolve the problems caused by this constraint on the availability of reliability data. By utilizing the technical knowledge about a program, a test, and test data, we can select an appropriate software reliability analysis model for accurate quality assessment. The delayed S-shaped growth model, the inflection S-shaped model, and the hyperexponcntial model are proposed. A logarithmic reliability-growth model for single-mission systems. J. M. F1NKELSTEIN. IEEE Trans. Reliab. R-32 (5), 508 (1983). A logarithmic growth model for the reliability of single-mission systems is proposed, and estimators for its two parameters are analyzed. Reliability growth produced by a 'test, analyze, and fix' (TAAF) program has a discrete measure of size, viz, the number of tests. The proposed growth model is similar to the popular nonhomogeneous Poisson process (Duane) growth models, and uses the discrete testnumber variable in place of test time. Analysis of simulation results shows that the continuous analog estimators arc superior to the least squares estimators. Both sets of estimators are s-consistent for a large number of tests, have acceptably small variability, and are easy to calculate. The continuous analog estimators have less variability than the least squares estimators and underestimate reliability, while the least squares estimators overestimate reliability. The application of the model, with the continuous analog estimators, to planning and monitoring the reliability development test program for a single-mission system is described. Adaptive robust estimation based on a family of generalized exponential power distributions. GEORGE E. CROWDER and ALBERT H. MOORE. IEEE Trans. Reliab. R-32 (5), 488 (1983). This paper suggests using the family of exponential power (EP) distributions to model data which are believed (a priori) to be essentially symmetric but where the usual assumptions of s-normality is unwarranted. Four estimation procedures are proposed for the parameters of the distribution. Two procedures are based on variations of the method of maximum likelihood (ML) while the other two use the method of MR 25:3-L
583
Reliability of plastic-encapsulated integrated circuits in moisture environments. L. GALLACEand M. ROSENFIELD.RCA Rev. 45, 249 (1984). An overview of the factors affecting the reliability of plastic-encapsulated ICs in moisture environments is presented. Particular attention is given to the moisture-related failure mechanism EMA (electrolytic metal attack). The package design and process steps and techniques developed at RCA (through identification of the proper analytical models, thorough engineering programs, and by the statistical design of experiments) are detailed. Particular attention was paid to eliminating chlorides and their sources. The nature and state of on-going plastic-package moisture-resistance programs and future expectations are described. Current problems in v.i.s.i, testing and testability. P. K. LALA. Radio Electron. Engr 54 (10), 415 (1984). This paper presents the basic concepts in testing, beginning with fault-models, and summarizes the major contributions to the design of testable logic. It identifies some of the current problems in v.l.s.i, testing and testability which need further investigation.
MAINTENANCE
AND
REDUNDANCY
moments to estimate the shape parameter but employ ML to estimate the location and scale parameters of the model. A Monte Carlo analysis compares the mean square errors of the estimators of the location and scale parameters of the model. Sample sizes 4(4)28 were drawn 2000 times from five symmetric probability distributions. A minimax criterion was used to evaluate each of the estimators. Comparison with adaptive and nonadaptive estimates of location and scale parameters show that the new procedure provides: (1) good estimates of scale and location parameters, and (2) a complete probability model for the data.
Testing ultra high speed devices. PETER H. SINGER. Semiconductor Int. 48 (September 1984). Many of today's stateof-the-art MOS and bipolar devices operate at speeds approaching the limits of most standard ATE. New GaAs and VHSIC technologies are also pushing the limits of high speed testing. Resilient concurrency control in distributed database systems. BHARAT BHARGAWA. IEEE Trans. Reliab. R-32 (5), 437 (1983). This paper presents the resiliency features of the optimistic approach to concurrency control and demonstrates how it lends itself to a design of a reliable distributed database system. The validation of concurrency control, integrity control, and atomicity control has been integrated. This integration provides a high degree of concurrency and continuity of operations in spite of failures of transactions, processors, and communication system. Analytical study of the pointwise availability of a parallel redundant 2-out-of-N :F system under head-of-line repair echelon. P. P. GUPTA and SUNIL KUMAR MITTAL. QR J. 55 (May 1984). The paper presents a multicomponent repairable system with two classes (A, B) of components. Class A consists of two identical components in parallel redundancy whereas B involves N-non identical components with l-outo f - N : D and 2-out-of-N:F arrangements. The reliability parameters are derived for the exponential failure and general repair time distributions under FIFO policy for repair. Particular cases are explained. The behaviour of time dependent availability of the system has been evaluated in a numerical example by inverting the L.T. An accurate probability-of-failure calculation method. A. HARBITZ. IEEE Trans. Reliab. R-32 (5), 458 (1983). Based on rules of transformation of stochastic variables, a general and