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Reliability appraisal for complex equipment
404
World Abstracts on Microelectronics and Reliability
approach is being increasingly used to develop planned growth curves.
Assessment of system reliability in electronics. A. J. BOURNE. Radio Electron. Enqr 48, [7) 323 (July'August 1978~. An overall concept of reliability and its application is fundamental in assessing electronic systems where such aspects as safety and availability are of prime importance. The need for, and the depth of, assessment tends to depend on human or financial risks involved with the particular system. Appropriately, the quantification of reliability has played an important part in the current development of assessment techniques where the aim has been to assess reliability with a minimum of subjectiveness. In the assessment process it has been necessary to employ a combination of methods based on field experience and theoretical prediction. The syn thesis o f the reliability of systems in the early stages of design has become an essential part of reliability growth and understanding. The techniques involved in this process extend from the analysis of capability to the likely variation in performance of the system. When the achieved performance is compared with the required performance an overall reliability function may be expressed. Performance spectrum methods of analysis and boundary approaches require to be integrated with the availability of the appropriate reliability data. The paper describes the general approach made in this field of assessment taking particular electronic and control systems as examples.
Yield-area analysis: Part I--A diagnostic tool for fundamental integrated-circuit process problems. W. E. HAM. RCA Rev. 39, 231 (June 1978). This paper considers the nature and value of the information contained in the distribution of good circuits across production IC wafers. It is shown that the actual production wafers are perhaps the only source of information available at reasonable effort and cost which reliably reflects the true yield-limiting factors existing in the process. Communication with these factors can be aided by analyzing the shape and orientation of the regions of the wafer wherein zero yield is obtained-thus, yield-area analysis. Fundamental divisions are made between parametric and point-defect limited yield. The key factor that allows the separation of these types is the quasi continuity of parametric values across wafers. It is suggested that any yield formula that assumes that point defects are the dominant yield-limiting factor must be multiplied by an area usage factor (AUF) which reflects the total fraction of available area being used for nonzero yield. On many wafers the A U F is less than 0.2, thereby making it one of the most important characteristic parameters of the process. Yield-area analysis can be a very powerful tool to guide the improvement of existing processes, and the A U F should be considered a fundamental design parameter for new circuit types.
Reliability appraisal for complex equipment. P. D. ANDRE. Proc. IEEE A. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978, p. 318. This paper describes the first phase of a study into reliability demonstration test procedures as applied to short production runs of large and complex Naval equipments. The study, jointly carried out with the Reliability Research Group of the Admiralty Surface Weapons Establishment, Portsmouth, England, has resulted in the development of a new approach to reliability demonstration techniques. The approach was derived after a study of current test procedures and the evaluation of the operational performance of selected equipments in use onboard HM Ships. . The new method requires equipment manufacturers to be assessed for their capability to recognize and minimize systematic failure modes. Capable manufacturers can then
produce equipment with the desired reliability characteristics. Further work developing the contractual, cost and technical aspects of the method is in progress.
Logistics supportability testing. MICHAEL D. JONES and ROGER MIELEC. Proc. [EEE .4. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978. p. 17. The United States Army conducts operational tests on hardware systems during their development cycle. These test results are used to make decisions to continue development/stop development/enter production. While logistics supportability has always been a part of these decisions--especially reliability and maintainability of the hardware--recently there has been increased emphasis on the testing of logistics. No methodology was available to assure that logistics was completely and adequately addressed. This paper describes a methodology which attempts to fill that void. The procedure defines logistics issues and operational test and evaluation methods so that each element and sub-element of logistics is evaluated based on the most realistic test conditions possible. Text book perfect. JOHN F. RADAVICH.Proc. IEEE ,4. Reliab. Maintainab. Syrup., Los Angeles. 17-19 January 1978, p. 367. Many material failures in the field are blamed onto defective material rather than abusive maintenance or repair practices. Text books dealing with failures stress the need for surface integrity. Rotating parts whose surfaces contain stress concentrators such as pits are subject to premature failure. There appears to be a lack of understanding of a few fundamentals of material behavior by many service and maintenance men.
Vikinglander reliability program. M. JOHN PILNY. Proc. IEEE A. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978, p. 136. The unique ~har'acteristics of the Viking landed ~ission presented difficult reliability challenges which have apparently been met, as represented by the unqualified success of this program. Significant new approaches to reliability tasks and parts program management were originated and implemented for the Viking lander; these proved effective and resulted in major cost savings. This paper describes the reliability (including parts) program tasks which were performed, some difficulties which were overcome, and briefly, the mission experience. The techniques developed should have application in future programs where strong emphasis is placed on success with low cost.
Fault tree a'nalysis with probability evaluation. C, L. PROCTOR, ASHOK M. KOTHARI and C. L. PROCTOR, lI. Proc. IEEE A. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978, p. 306. This paper presents the fault tree analysis with probability evaluation by use of Bolean logic. It provides an all inclusive, versatile mathematical tree for analyzing gate and/or gate operations. The construction criteria and the probability evaluation methods of fault trees are briefly discussed. The reliability equations of the basic logic units of the tree are presented. The probability evaluation by use of Bolean logic has been discussed for generating the minimal cut sets of a fault tree containing repetitions of basic events and is illustrated by means of a sample fault tree. The MTBF (mean time between failure) evaluation with use of the reliability approach are illustrated by means of simple example. The paper treats the simple series structure and the parallel structure. For each, the probability of success and probability of failure are derived.
Maintainability and life cycle costing. MITCHELL0. LOCKS. Proc. IEEE .4. Reliab. Maimainub. Syrup., Los Angeles, 17-19 January 1978, p. 251. In order to insure that hardware acquisition programs will result in the lowest possible overall cost the Government and other purchasers of electro-
World Abstracts on Microelectronics and Reliability
approach is being increasingly used to develop planned growth curves.
Assessment of system reliability in electronics. A. J. BOURNE. Radio Electron. Enqr 48, [7) 323 (July'August 1978~. An overall concept of reliability and its application is fundamental in assessing electronic systems where such aspects as safety and availability are of prime importance. The need for, and the depth of, assessment tends to depend on human or financial risks involved with the particular system. Appropriately, the quantification of reliability has played an important part in the current development of assessment techniques where the aim has been to assess reliability with a minimum of subjectiveness. In the assessment process it has been necessary to employ a combination of methods based on field experience and theoretical prediction. The syn thesis o f the reliability of systems in the early stages of design has become an essential part of reliability growth and understanding. The techniques involved in this process extend from the analysis of capability to the likely variation in performance of the system. When the achieved performance is compared with the required performance an overall reliability function may be expressed. Performance spectrum methods of analysis and boundary approaches require to be integrated with the availability of the appropriate reliability data. The paper describes the general approach made in this field of assessment taking particular electronic and control systems as examples.
Yield-area analysis: Part I--A diagnostic tool for fundamental integrated-circuit process problems. W. E. HAM. RCA Rev. 39, 231 (June 1978). This paper considers the nature and value of the information contained in the distribution of good circuits across production IC wafers. It is shown that the actual production wafers are perhaps the only source of information available at reasonable effort and cost which reliably reflects the true yield-limiting factors existing in the process. Communication with these factors can be aided by analyzing the shape and orientation of the regions of the wafer wherein zero yield is obtained-thus, yield-area analysis. Fundamental divisions are made between parametric and point-defect limited yield. The key factor that allows the separation of these types is the quasi continuity of parametric values across wafers. It is suggested that any yield formula that assumes that point defects are the dominant yield-limiting factor must be multiplied by an area usage factor (AUF) which reflects the total fraction of available area being used for nonzero yield. On many wafers the A U F is less than 0.2, thereby making it one of the most important characteristic parameters of the process. Yield-area analysis can be a very powerful tool to guide the improvement of existing processes, and the A U F should be considered a fundamental design parameter for new circuit types.
Reliability appraisal for complex equipment. P. D. ANDRE. Proc. IEEE A. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978, p. 318. This paper describes the first phase of a study into reliability demonstration test procedures as applied to short production runs of large and complex Naval equipments. The study, jointly carried out with the Reliability Research Group of the Admiralty Surface Weapons Establishment, Portsmouth, England, has resulted in the development of a new approach to reliability demonstration techniques. The approach was derived after a study of current test procedures and the evaluation of the operational performance of selected equipments in use onboard HM Ships. . The new method requires equipment manufacturers to be assessed for their capability to recognize and minimize systematic failure modes. Capable manufacturers can then
produce equipment with the desired reliability characteristics. Further work developing the contractual, cost and technical aspects of the method is in progress.
Logistics supportability testing. MICHAEL D. JONES and ROGER MIELEC. Proc. [EEE .4. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978. p. 17. The United States Army conducts operational tests on hardware systems during their development cycle. These test results are used to make decisions to continue development/stop development/enter production. While logistics supportability has always been a part of these decisions--especially reliability and maintainability of the hardware--recently there has been increased emphasis on the testing of logistics. No methodology was available to assure that logistics was completely and adequately addressed. This paper describes a methodology which attempts to fill that void. The procedure defines logistics issues and operational test and evaluation methods so that each element and sub-element of logistics is evaluated based on the most realistic test conditions possible. Text book perfect. JOHN F. RADAVICH.Proc. IEEE ,4. Reliab. Maintainab. Syrup., Los Angeles. 17-19 January 1978, p. 367. Many material failures in the field are blamed onto defective material rather than abusive maintenance or repair practices. Text books dealing with failures stress the need for surface integrity. Rotating parts whose surfaces contain stress concentrators such as pits are subject to premature failure. There appears to be a lack of understanding of a few fundamentals of material behavior by many service and maintenance men.
Vikinglander reliability program. M. JOHN PILNY. Proc. IEEE A. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978, p. 136. The unique ~har'acteristics of the Viking landed ~ission presented difficult reliability challenges which have apparently been met, as represented by the unqualified success of this program. Significant new approaches to reliability tasks and parts program management were originated and implemented for the Viking lander; these proved effective and resulted in major cost savings. This paper describes the reliability (including parts) program tasks which were performed, some difficulties which were overcome, and briefly, the mission experience. The techniques developed should have application in future programs where strong emphasis is placed on success with low cost.
Fault tree a'nalysis with probability evaluation. C, L. PROCTOR, ASHOK M. KOTHARI and C. L. PROCTOR, lI. Proc. IEEE A. Reliab. Maintainab. Syrup., Los Angeles, 17-19 January 1978, p. 306. This paper presents the fault tree analysis with probability evaluation by use of Bolean logic. It provides an all inclusive, versatile mathematical tree for analyzing gate and/or gate operations. The construction criteria and the probability evaluation methods of fault trees are briefly discussed. The reliability equations of the basic logic units of the tree are presented. The probability evaluation by use of Bolean logic has been discussed for generating the minimal cut sets of a fault tree containing repetitions of basic events and is illustrated by means of a sample fault tree. The MTBF (mean time between failure) evaluation with use of the reliability approach are illustrated by means of simple example. The paper treats the simple series structure and the parallel structure. For each, the probability of success and probability of failure are derived.
Maintainability and life cycle costing. MITCHELL0. LOCKS. Proc. IEEE .4. Reliab. Maimainub. Syrup., Los Angeles, 17-19 January 1978, p. 251. In order to insure that hardware acquisition programs will result in the lowest possible overall cost the Government and other purchasers of electro-