- Email: [email protected]
Mechanism of misalignment failure of liquid-crystal display devices
World Abstracts on Microelectronics and Reliability
586
Four decades of reliability progress---Annual reliability and
EZAWA. IEEE Trans. Reliab. 40(3), 296 (1991). Misalignment failure mechanisms, which are a problem in twisted Reliab. Maintainab. Symp., 156 (1991). Substantial re- nematic liquid-crystal display devices, are investigated. A liability progress has occurred in the four decades ending in life test which changes the driving conditions of the applied 1989. Technological advances, particularly in the field of multiplexing voltage is implemented for devices which use electronics, have unquestionably made much of this pro- estercy-clohexane liquid crystals. The life tests showed that gress possible. It is only natural to ask what the relative misalignment life is longer with a lower voltage, smaller duty contributions of these advances and the many other factors ratio, and a higher frequency. These results are highly that influence reliability have been. It is the intent of this appropriate for models with alternating current electrolysis paper to examine this question from a semi-quantitative and show that misalignment failure is caused by electrolysis historical basis and to infer, from this examination, possible of the liquid-crystal material. In addition, electrostatic lessons for the future. capacity and applied voltage properties were used to study the relationship of liquid-crystal dielectric anisotropy and the coupling coefficient with temporal misalignment Mechanism of misalignment failure of liquid-crystal display changes. The coupling coefficient decreases along with misdevices. IZ~NjI KITAOAWA,YOJI KANUMA and MASAYOSHI alignment failure.
malntninnblilty symposimn. C. RAYMOND KNIGHT. Proc. A.
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Improved reliablfitypredictions for colnmertcal computers. N. I~ITM HERGATI'.Prec. A. Reliab. Maintainab. Symp., 357 (1991). A model is needed to predict field reliability of small commerical computers, office work stations and PC servers. This paper demonstrates that MIL-HDBK-217E predictions are overly conservative for both system and components in a small system in the office environment. The data collected and analyzed for this report suggest the quality factor (P0) and the environmental factor (Pc) used in MIL-HDBK-217E predictions need modification for office work stations. The data support the P0 recommended by Scidl and Gerry and suggests the descriptions of environmental conditions for determining for P~. It also provides working values for some families of components in the office work station system, however, not enough data are available for a comprehensive model at this time.
MAINTENANCE
AND
REDUNDANCY
Supplier auditing as a means of quality assurance. PdCHAgD C. G. SWANN. Quality Europe, 11 (1991). Auditing of suppliers is a valuable tool in a customer's quality assurance (QA) programme, provided that it is carefully planned and conducted as a part of an integrated quality assurance system. In this paper a model for integrated circuits (ICs) is described. Supplier auditing includes detailed surveys of all manufacturing and testing sites related to specific components as wafer fabrication, assembly, and testing for ICs. The described model is also applicable to a wide range of other components and materials.
Interde~ndence between safety-control policy and multiplesensor schemes via DemlBter-Shafer theory. IEEE Trans. Reliab. 40(2), 182 (1991). The Dempster-Shafer (D-S) theory has been gaining popularity in fields where incomplete knowledge is a factor. This paper explores the application of the D-S theory in system reliabilityand safety. Inappropriate application of the D-S theory to safetycontrol policies can degrade plant safety. This is proven in two phases: (1) a new unified combination rule for fusing information on plant statesgiven by independent knowledge sources such as sensors or human operators isdeveloped; (2) combination rules cannot be chosen in an arbitrary manner; i.e.the best choice of combination rulesdepends on whether the safety-control policy is fault-warning or safety-preser-
Field reliability vs predicted reHabUity: an analysis of root causes for the difference. PHILLIP E. MILLERand RICHARD I. MOOP,£. Proc. A. Reliab. Maintainab. Syrup.,405 (1991). The significantdifferencebetween predicted reliabilityand actual reliability of fielded systems---what we have termed the "reliability delta"--has been a long-standing problem in reliabilityengineering. An extensive literature review was conducted to identifyroot causes contributing to this differonce. In addition, SAS analysis of data collected in a 1988 study yielded interesting results. This research asked 38 vation. reliability experts from the Department of Defense and Industry to identify the rank order factors which potentially Trend analysisof repairlimes. KA~N E. ELLISand G~C, ORY contributed to the reliabilitydelta. Total quality manageJ. GmsoN. Proc. A. Reliab. Maintainab. Syrup.,85 (1991). ment (TQM) tools were used to analyze the relationships Results of applying the Crow (army material systems analyamong and impact of key variances on the reliability sis activity (AMSAA)) and Kalman filter(KF) models to prediction process and explain apparent differencesbetween repair time data are examined. Repair rates (I/MTTR), as the DoD and industry perspectives. equipment operation continues and maintenance procedures The literature review identified eleven factors as possible mature, can be successfully analyzed using either of these causes of the reliability delta; however, only six were noted procedures. Instantaneous MTTR estimates are assessed as being significant by the experts. The six factors identified from the model outputs, and future MTTRs are predicted were: problems with data collection, assumptions under- based on the resultsof model fits.Both models corroborate lying and use of prediction techniques, lack of understandthe results found with each independently; however, the ing of the operational environment, problems with technical approach and interpretation of the results differ manufacturing processes, short-term management focus, due to modeling reference frames. and design-related problems. Each of these factors was evaluated from both DoD and industry perspectives. lntegrut~l of materials testing systems into user-specific Although the same six factors were identified by both groups, the rank order of the importance of these factors software strncturns. HANS-JURGENWAONER and KLAUS EIS~N~I~,NN, Quality Europe (Germany), 37 (1991). Intewas virtually reversed between DoD and industry personnel. The contrasting priorities may in part explain the focus of gration of materials testing equipment with an in-house management efforts of one group on factors which are computer system requires extensive application programs. considered less important by the other. The final section Such programs aid the setting up of a laboratory network highlights some of the logistics impacts of the reliability and linking to a main frame computer. Economic benefits arising from the enormous increase in laboratory computer data.
586
Four decades of reliability progress---Annual reliability and
EZAWA. IEEE Trans. Reliab. 40(3), 296 (1991). Misalignment failure mechanisms, which are a problem in twisted Reliab. Maintainab. Symp., 156 (1991). Substantial re- nematic liquid-crystal display devices, are investigated. A liability progress has occurred in the four decades ending in life test which changes the driving conditions of the applied 1989. Technological advances, particularly in the field of multiplexing voltage is implemented for devices which use electronics, have unquestionably made much of this pro- estercy-clohexane liquid crystals. The life tests showed that gress possible. It is only natural to ask what the relative misalignment life is longer with a lower voltage, smaller duty contributions of these advances and the many other factors ratio, and a higher frequency. These results are highly that influence reliability have been. It is the intent of this appropriate for models with alternating current electrolysis paper to examine this question from a semi-quantitative and show that misalignment failure is caused by electrolysis historical basis and to infer, from this examination, possible of the liquid-crystal material. In addition, electrostatic lessons for the future. capacity and applied voltage properties were used to study the relationship of liquid-crystal dielectric anisotropy and the coupling coefficient with temporal misalignment Mechanism of misalignment failure of liquid-crystal display changes. The coupling coefficient decreases along with misdevices. IZ~NjI KITAOAWA,YOJI KANUMA and MASAYOSHI alignment failure.
malntninnblilty symposimn. C. RAYMOND KNIGHT. Proc. A.
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Improved reliablfitypredictions for colnmertcal computers. N. I~ITM HERGATI'.Prec. A. Reliab. Maintainab. Symp., 357 (1991). A model is needed to predict field reliability of small commerical computers, office work stations and PC servers. This paper demonstrates that MIL-HDBK-217E predictions are overly conservative for both system and components in a small system in the office environment. The data collected and analyzed for this report suggest the quality factor (P0) and the environmental factor (Pc) used in MIL-HDBK-217E predictions need modification for office work stations. The data support the P0 recommended by Scidl and Gerry and suggests the descriptions of environmental conditions for determining for P~. It also provides working values for some families of components in the office work station system, however, not enough data are available for a comprehensive model at this time.
MAINTENANCE
AND
REDUNDANCY
Supplier auditing as a means of quality assurance. PdCHAgD C. G. SWANN. Quality Europe, 11 (1991). Auditing of suppliers is a valuable tool in a customer's quality assurance (QA) programme, provided that it is carefully planned and conducted as a part of an integrated quality assurance system. In this paper a model for integrated circuits (ICs) is described. Supplier auditing includes detailed surveys of all manufacturing and testing sites related to specific components as wafer fabrication, assembly, and testing for ICs. The described model is also applicable to a wide range of other components and materials.
Interde~ndence between safety-control policy and multiplesensor schemes via DemlBter-Shafer theory. IEEE Trans. Reliab. 40(2), 182 (1991). The Dempster-Shafer (D-S) theory has been gaining popularity in fields where incomplete knowledge is a factor. This paper explores the application of the D-S theory in system reliabilityand safety. Inappropriate application of the D-S theory to safetycontrol policies can degrade plant safety. This is proven in two phases: (1) a new unified combination rule for fusing information on plant statesgiven by independent knowledge sources such as sensors or human operators isdeveloped; (2) combination rules cannot be chosen in an arbitrary manner; i.e.the best choice of combination rulesdepends on whether the safety-control policy is fault-warning or safety-preser-
Field reliability vs predicted reHabUity: an analysis of root causes for the difference. PHILLIP E. MILLERand RICHARD I. MOOP,£. Proc. A. Reliab. Maintainab. Syrup.,405 (1991). The significantdifferencebetween predicted reliabilityand actual reliability of fielded systems---what we have termed the "reliability delta"--has been a long-standing problem in reliabilityengineering. An extensive literature review was conducted to identifyroot causes contributing to this differonce. In addition, SAS analysis of data collected in a 1988 study yielded interesting results. This research asked 38 vation. reliability experts from the Department of Defense and Industry to identify the rank order factors which potentially Trend analysisof repairlimes. KA~N E. ELLISand G~C, ORY contributed to the reliabilitydelta. Total quality manageJ. GmsoN. Proc. A. Reliab. Maintainab. Syrup.,85 (1991). ment (TQM) tools were used to analyze the relationships Results of applying the Crow (army material systems analyamong and impact of key variances on the reliability sis activity (AMSAA)) and Kalman filter(KF) models to prediction process and explain apparent differencesbetween repair time data are examined. Repair rates (I/MTTR), as the DoD and industry perspectives. equipment operation continues and maintenance procedures The literature review identified eleven factors as possible mature, can be successfully analyzed using either of these causes of the reliability delta; however, only six were noted procedures. Instantaneous MTTR estimates are assessed as being significant by the experts. The six factors identified from the model outputs, and future MTTRs are predicted were: problems with data collection, assumptions under- based on the resultsof model fits.Both models corroborate lying and use of prediction techniques, lack of understandthe results found with each independently; however, the ing of the operational environment, problems with technical approach and interpretation of the results differ manufacturing processes, short-term management focus, due to modeling reference frames. and design-related problems. Each of these factors was evaluated from both DoD and industry perspectives. lntegrut~l of materials testing systems into user-specific Although the same six factors were identified by both groups, the rank order of the importance of these factors software strncturns. HANS-JURGENWAONER and KLAUS EIS~N~I~,NN, Quality Europe (Germany), 37 (1991). Intewas virtually reversed between DoD and industry personnel. The contrasting priorities may in part explain the focus of gration of materials testing equipment with an in-house management efforts of one group on factors which are computer system requires extensive application programs. considered less important by the other. The final section Such programs aid the setting up of a laboratory network highlights some of the logistics impacts of the reliability and linking to a main frame computer. Economic benefits arising from the enormous increase in laboratory computer data.