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A creep-rupture model for two-phase eutectic solders
1094
World Abstracts on Microeleclronics and Reliability
We consider the problem of acceptance testing for a parallel (1-out-of-n: G) system of different components with constant failure rates. The components are individually tested and the tests are terminated as soon as a preassigned number of each component fails. This paper provides a criterion for accepting or rejecting the system based on the sum of the logarithms of the total times on test for each component. The critical level for the test statistic is chosen so as to guarantee that the specified consumer and producer risks on the system reliability are not exceeded. The use of this statistic makes the computation of these critical values much simpler as compared with that of a previously used statistic based on the product of the total times on test for each component. Several approximate procedures are considered for deriving these critical values. The paper also formulates the optimization problem for deriving the minimum-cost component-testing plans when a type-ll censored component-test procedure is used for a parallel system.
Failure analysis of glass sealed thermistor for ~nsor and development of its evaluation method. N. TSUTSUMI and H. YAS'CDA. Proc, lSth Symp, Reliab. Maintainab. (Condensed Versionk 47 (1988). There arc many cases where a glass sealed thermistor is used as a thermal sensor for a severe temperature and humidity environment. The failure mode unique to this sensor includes glass crack caused by stress. However, it is extremely difficult to generate this crack by a general evaluation method. This report reveals an example of developing a new evaluation method applying "design of experiment" and failure analysis. A creep-rupture model for two-phase eutectic solders. BOON WON(;, DONAt.I) E. HILLING and RoY W. CLARK, IEEE Trans. Compon. Hybrids rt!fg Technol. 11, C H M T - 284 (1988). In solders, creep rupture is usually believed to be the dominant cause of damage and failure at high temperatures and low stresses or under low-frequency thermal cycling conditions. This investigation establishes an analytical framework to predict failure of solders under creep conditions. A creep-rupture model for two-phase eutectic solders based on both micromechanics and fracture mechanics has been developed. The general agreement between the model predictions and reported creep-rupture data in the literature for lead/tin eutectic solder indicates that the mode and mechanisms proposed in the model may control the solder creep-rupture process.
Development of highly reliable surface mount packages. KAZUYA FI;JFIA, KAYOKO UEMtJRA, SYOZO MINAM1DE and TAKAMICH1 MAE1)A. Proc. 18th Syrup. Reliab. Maintainab. (Condensed Version), 31 (1988). The soldering techniques commonly used for the surface m o u n t packages (SOP, QFP, etc.) include infrared reflow, vapor phase reflow, dip, and other techniques which usually heat the packages to soldering temperatures. The sudden thermal stresses to which the compact lov, profile packages are exposed during soldering can cause cracks in the packages and degraded moisture rcsistallCt2. As a solution to these problems, we have developed a crack-proof surface mount package which does not require moisture absorption control or increased package thickness.
Aluminum corrosion at pad bond in the humidity tests. Y. KOnAYASHI and T. WADA. Proc. t8th Syrup. Reliab. Maintainah. (Condensed Version), 37 (1988). Since the trend of semiconductor devices is toward finer dimensions, higher integration and smaller package, AI corrosion and the change of electrical characteristics become the more important failure modes of plastic encapsulated semi-conductor devices when encountering a moist environment. In this report, the A1 corrosion was studied with the discussion as follows: (I) the conditions which AI corrosion at
pad bond occurs; (2) the path of moisture penetration into package and the effect of local cell reaction between AI pad and Au wire; (3) the comparison with AI wire and Au wire.
How to test mixed-signal ICs. STEPHEN F. SCHEIBER. Test Measuremt WId, 81 (September 1988). Manufacturing devices that combine analog and digital functions require integrated test solutions. Careless pump maintenance will cost you. KATHLEEN M. KEARNEY. Semiconductor int., 77 (September 1988). Negligent or improper p u m p maintenance can cause system failure and threaten personnel safety. Optimal wear-limit replacement with wear-dependent failures. KYUNG S. PARK. IEEE Trans. Reliab. R-37, 293 (1988). An item with wear-dependent failure rate is replaced when it wears beyond a preset wear limit; or on failure. This seemingly complex wear-failure process gives rise to a simple strategy akin to the age replacement policy. Replacement vs repair of failed components for a system with a random lifetime. CHARLES E. WELLS. IEEE Trans. Reliab. R-37, 280 (1988). This paper investigates the computation of a variety of reliability measures for a system that is observed over a random time horizon. This time interval which can correspond to the system mission, the system lifetime, etc., is assumed to be distributed as a random variable of phase type. Models are developed which aid a decision maker to choose a m o n g the actions of replace, repair, or do nothing, whenever a system component fails under several assumptions concerning the amount of information available to the decision maker. In addition, a policy of replacement after a fixed number of repairs is examined. An example computation of several reliability measures and the application of a cost model is included to illustrate the tractability of the results and their usefulness in design decisions. Physical design of circuit boards for testability and maintainability. B. R. W1LKINS.J. In,stn Electron. Radio En#s 58(5), 217 (1988). Electronic systems are almost invariably built with a hierarchical structure, and testing procedures and Automatic Test Equipment fATE) have been developed to permit verification of correct operation of the system and of its component modules at all levels of the hierarchy. As circuit complexities increase, it has become increasingly clear that circuits have to be designed to suit the ATE if the testing costs are to be contained to an acceptable level. Developments in electronics over the last few years have not brought about any fundamental changes in circuit techniques or basic circuit components. There have, however, been dramatic changes in a number of aspects of mechanical technology. These changes impact in m a n y different ways on the demands placed on the ATE and hence on the strategies that need to be adopted by system manufacturers for test, repair, maintenance, and field service. These considerations should, in turn, influence the initial design of the system: design for testability (DFT) needs to embrace mechanical as well as electrical considerations. This paper reviews some of the changes that are taking place in the mechanical structure of electronic components and circuits, and discusses how these changes affect testability. Finally, it describes a new constructional technique (Hierarchical Interconnection Technology HIT) which is intended to address some of the problems, Some reliability problems of surface-mounted devices. TOKlO MUTO. IEEE Circuits Devices Ma,q., 9 (July 1988). Not only has the performance of electronic equipment been continuously improving, but such equipment has undergone revolutionary changes in its basic structure. One of these changes is the result of fabrication of electron devices using high-density assembly technology. One of the most success-
World Abstracts on Microeleclronics and Reliability
We consider the problem of acceptance testing for a parallel (1-out-of-n: G) system of different components with constant failure rates. The components are individually tested and the tests are terminated as soon as a preassigned number of each component fails. This paper provides a criterion for accepting or rejecting the system based on the sum of the logarithms of the total times on test for each component. The critical level for the test statistic is chosen so as to guarantee that the specified consumer and producer risks on the system reliability are not exceeded. The use of this statistic makes the computation of these critical values much simpler as compared with that of a previously used statistic based on the product of the total times on test for each component. Several approximate procedures are considered for deriving these critical values. The paper also formulates the optimization problem for deriving the minimum-cost component-testing plans when a type-ll censored component-test procedure is used for a parallel system.
Failure analysis of glass sealed thermistor for ~nsor and development of its evaluation method. N. TSUTSUMI and H. YAS'CDA. Proc, lSth Symp, Reliab. Maintainab. (Condensed Versionk 47 (1988). There arc many cases where a glass sealed thermistor is used as a thermal sensor for a severe temperature and humidity environment. The failure mode unique to this sensor includes glass crack caused by stress. However, it is extremely difficult to generate this crack by a general evaluation method. This report reveals an example of developing a new evaluation method applying "design of experiment" and failure analysis. A creep-rupture model for two-phase eutectic solders. BOON WON(;, DONAt.I) E. HILLING and RoY W. CLARK, IEEE Trans. Compon. Hybrids rt!fg Technol. 11, C H M T - 284 (1988). In solders, creep rupture is usually believed to be the dominant cause of damage and failure at high temperatures and low stresses or under low-frequency thermal cycling conditions. This investigation establishes an analytical framework to predict failure of solders under creep conditions. A creep-rupture model for two-phase eutectic solders based on both micromechanics and fracture mechanics has been developed. The general agreement between the model predictions and reported creep-rupture data in the literature for lead/tin eutectic solder indicates that the mode and mechanisms proposed in the model may control the solder creep-rupture process.
Development of highly reliable surface mount packages. KAZUYA FI;JFIA, KAYOKO UEMtJRA, SYOZO MINAM1DE and TAKAMICH1 MAE1)A. Proc. 18th Syrup. Reliab. Maintainab. (Condensed Version), 31 (1988). The soldering techniques commonly used for the surface m o u n t packages (SOP, QFP, etc.) include infrared reflow, vapor phase reflow, dip, and other techniques which usually heat the packages to soldering temperatures. The sudden thermal stresses to which the compact lov, profile packages are exposed during soldering can cause cracks in the packages and degraded moisture rcsistallCt2. As a solution to these problems, we have developed a crack-proof surface mount package which does not require moisture absorption control or increased package thickness.
Aluminum corrosion at pad bond in the humidity tests. Y. KOnAYASHI and T. WADA. Proc. t8th Syrup. Reliab. Maintainah. (Condensed Version), 37 (1988). Since the trend of semiconductor devices is toward finer dimensions, higher integration and smaller package, AI corrosion and the change of electrical characteristics become the more important failure modes of plastic encapsulated semi-conductor devices when encountering a moist environment. In this report, the A1 corrosion was studied with the discussion as follows: (I) the conditions which AI corrosion at
pad bond occurs; (2) the path of moisture penetration into package and the effect of local cell reaction between AI pad and Au wire; (3) the comparison with AI wire and Au wire.
How to test mixed-signal ICs. STEPHEN F. SCHEIBER. Test Measuremt WId, 81 (September 1988). Manufacturing devices that combine analog and digital functions require integrated test solutions. Careless pump maintenance will cost you. KATHLEEN M. KEARNEY. Semiconductor int., 77 (September 1988). Negligent or improper p u m p maintenance can cause system failure and threaten personnel safety. Optimal wear-limit replacement with wear-dependent failures. KYUNG S. PARK. IEEE Trans. Reliab. R-37, 293 (1988). An item with wear-dependent failure rate is replaced when it wears beyond a preset wear limit; or on failure. This seemingly complex wear-failure process gives rise to a simple strategy akin to the age replacement policy. Replacement vs repair of failed components for a system with a random lifetime. CHARLES E. WELLS. IEEE Trans. Reliab. R-37, 280 (1988). This paper investigates the computation of a variety of reliability measures for a system that is observed over a random time horizon. This time interval which can correspond to the system mission, the system lifetime, etc., is assumed to be distributed as a random variable of phase type. Models are developed which aid a decision maker to choose a m o n g the actions of replace, repair, or do nothing, whenever a system component fails under several assumptions concerning the amount of information available to the decision maker. In addition, a policy of replacement after a fixed number of repairs is examined. An example computation of several reliability measures and the application of a cost model is included to illustrate the tractability of the results and their usefulness in design decisions. Physical design of circuit boards for testability and maintainability. B. R. W1LKINS.J. In,stn Electron. Radio En#s 58(5), 217 (1988). Electronic systems are almost invariably built with a hierarchical structure, and testing procedures and Automatic Test Equipment fATE) have been developed to permit verification of correct operation of the system and of its component modules at all levels of the hierarchy. As circuit complexities increase, it has become increasingly clear that circuits have to be designed to suit the ATE if the testing costs are to be contained to an acceptable level. Developments in electronics over the last few years have not brought about any fundamental changes in circuit techniques or basic circuit components. There have, however, been dramatic changes in a number of aspects of mechanical technology. These changes impact in m a n y different ways on the demands placed on the ATE and hence on the strategies that need to be adopted by system manufacturers for test, repair, maintenance, and field service. These considerations should, in turn, influence the initial design of the system: design for testability (DFT) needs to embrace mechanical as well as electrical considerations. This paper reviews some of the changes that are taking place in the mechanical structure of electronic components and circuits, and discusses how these changes affect testability. Finally, it describes a new constructional technique (Hierarchical Interconnection Technology HIT) which is intended to address some of the problems, Some reliability problems of surface-mounted devices. TOKlO MUTO. IEEE Circuits Devices Ma,q., 9 (July 1988). Not only has the performance of electronic equipment been continuously improving, but such equipment has undergone revolutionary changes in its basic structure. One of these changes is the result of fabrication of electron devices using high-density assembly technology. One of the most success-