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Component verification system
278
World Abstracts on Microelectronics and Reliability
diode. This same technique should be useful for most device reliability predictions. The acceleration factors, however, can not be extrapolated into stress levels much above m a x i m u m ratings where new failure modes may appear that override the established failure rate relation with stress. The straight line plots of failure rates in this paper are terminated before these threshold limits.
Unsoldering p.c.b's without damage. J. A. SCARLETT.Electron. Power p. 715 (September 1980). Printed-circuit boards and soldered joints form the basis of almost all electronic equipments, and it might be thought that the industry should by now be so thoroughly familiar with both boards and joints that there can no longer be any major problems associated with the making and unmaking of joints. However, this is far from being the case.
Component verification system. DARYL D. SCHROEDER and ROBERT E. HINES. IEEE Trans. Components, Hybrids MJi~y Technol. C H M T - 3 (3), 367 (September 1980). Typical hybrid microcircuits (HMC's) manufactured at the Bendix Corporation, Kansas City, MO, contain 100 beam lead devices and gold ribbon crossovers. Verification for the presence of these applique components historically has been done manually by comparing a visual aid to the HMC. All H M C ' s were verified visually, a process requiring 4 - 5 m i n / H M C . Approximately 12 percent of the defects were missed. A system has been developed for automatically verifying the presence of beam lead devices and ribbon crossovers. The component verification system (CVS) includes a minicomputer-controlled X - Y stage which indexes the H M C below a vidicon camera. The camera is interfaced to the computer through a video digitizer. Bendix-developed software uses the equipment capabilities to magnify and project a 5.1-mm 2 area onto a 177.8-mm 2 screen with the image data points addressable in a 512 by 480 line matrix. The image analysis software determines component presence based on data point brightness. The CVS can verify beam lead device and crossover presences on a typical H M C in fewer than 30 s. The part identification of any missing part is printed as
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Concepts for calculating frequency of system failure. C. SINGH and A. D. PATTON. IEEE Trans. Reliab. R-29 (4), 336 (October 1980). This paper presents a frequency-balance concept which is more general than that for disjoint subsets, and describes recursive relationships for the frequency of a union of subsets or events.
an aid to rework. The CVS has reduced the time needed for component verification and has improved verification accuracy.
Low-field time-dependent dielectric integrity. EUGENE S. ANOLICK and GLENN R. NELSON. IEEE Trans. Reliab. R-29 (3), 217 (August 1980). A major contributor to reliability failures in integrated circuits has been the failure of dielectrics under operating stress. This paper surnmarizes extensive studies carried out on many manifestations of dielectric integrity failure. The outcome is a single model used to predict failure from data obtained in accelerated testing. The model contains the effect of temperature and applied voltage on the tendency to fail as well as the breakdown of the region subject to stress.
Voltage breakdown testing of relays in the 100-V range. EOIN W. GRAY and THOMAS A. UHRIG. IEEE Tran6. Components, Hybrids MJh9 Technol. C H M T - 3 (3). 442 (September 1980). The ac voltage breakdown between adjacent conductors separated by an insulator on relays has been examined using two types of breakdown test sets and a sensitive corona (partial discharget detector. A large difference in the breakdown voltages was observed on relays from the same population using two breakdown test sets. The characteristics of the test sets were examined to identify the cause of the breakdown difference. The breakdown voltage is independent of the voltage ramp speed from 55 to 8300V/s. It is also independent of the series resistance up to 300k~. The different detector systems do not contribute to the breakdown difference. The output capacitance of the breakdown test sets appears to be quite important to the voltage breakdown of the samples. Modification of the output of the test sets leads to similar breakdown valves. The prebreakdown discharges observed using the corona detector suggests that breakdown is a gas breakdown type. Effects on the insulator surfaces caused by the testing are considered in light of the prebreakdown discharge measurements and are expected to be minimal. These results should be applicable to the moderately high voltage testing of other products, although the numerical values will probably differ.
MAINTENANCE
AND
REDUNDANCY
might be useful for some reliability optimization procedures and other applications.
Reliability of all possible series-parallel redundant structures of M.I.I.D. units with two failure modes. YuJt NAKAGAWA and YOSHIO HATTORI. IEEE Trans. Reliab. R-29 (4), 320
An algebraic technique for reliability evaluation. R. K. TIWARI and MIKKt VERMA. IEEE Trans. Reliab. R-29 (4), 311 (October 1980). An algebraic technique is proposed to obtain a simplified reliability expression of a general system. A success expression which directly gives the reliability expression, is formed and simplified by the procedure. The technique is equally efficient for simple and complex systems; yields computationally efficient reliability expressions; is routine (no decision making); yields an expression having a m i n i m u m number of product terms; and is easier than many existing techniques.
(October 1980). The paper presents a method for generating systematically and exactly all possible series-parallel (s-p) structures for several i.i.d, units. The method, is modified in order to calculate the failure probabilities and reliabilities of all the possible s-p redundant structures for the i.i.d, units with two failure modes. Included is an example of finding an optimal s-p redundant structure subject to four constraints for reliability (two for failure probabilities and two for fail-safe).
Synthesis and number of all series-parallel structures with n components. WINFRID G. SCHNEEWEISS and KLAUS D. HEIDTMANN. IEEE Trans. Reliab. R-29 (4), 315 (October
"Quality" is defined as degree of conformance of an item with reference to its intended use. This includes the time factors from its design to disposal characteristic of a product from womb to tomb. In this paper several aspects of a quality product in respect of avionic equipment are considered during the various stages from design, development, testing, production, transportability, uses and ease of maintenance till an item is discarded after declaring it as obsolete.
1980). A synthesis procedure a n d - - a s a by-product--the number of different redundant structures for series-parallel systems with n components is derived. The reliability graphs of these structures, especially their fault trees, are branched like true rooted trees in the sense of graph theory. The results
Quality and reliability of avionic equipment. R. SOIvlASUNDARAM and R. S. YADAV. The QR JI {India) p. 73 (May 1980).
World Abstracts on Microelectronics and Reliability
diode. This same technique should be useful for most device reliability predictions. The acceleration factors, however, can not be extrapolated into stress levels much above m a x i m u m ratings where new failure modes may appear that override the established failure rate relation with stress. The straight line plots of failure rates in this paper are terminated before these threshold limits.
Unsoldering p.c.b's without damage. J. A. SCARLETT.Electron. Power p. 715 (September 1980). Printed-circuit boards and soldered joints form the basis of almost all electronic equipments, and it might be thought that the industry should by now be so thoroughly familiar with both boards and joints that there can no longer be any major problems associated with the making and unmaking of joints. However, this is far from being the case.
Component verification system. DARYL D. SCHROEDER and ROBERT E. HINES. IEEE Trans. Components, Hybrids MJi~y Technol. C H M T - 3 (3), 367 (September 1980). Typical hybrid microcircuits (HMC's) manufactured at the Bendix Corporation, Kansas City, MO, contain 100 beam lead devices and gold ribbon crossovers. Verification for the presence of these applique components historically has been done manually by comparing a visual aid to the HMC. All H M C ' s were verified visually, a process requiring 4 - 5 m i n / H M C . Approximately 12 percent of the defects were missed. A system has been developed for automatically verifying the presence of beam lead devices and ribbon crossovers. The component verification system (CVS) includes a minicomputer-controlled X - Y stage which indexes the H M C below a vidicon camera. The camera is interfaced to the computer through a video digitizer. Bendix-developed software uses the equipment capabilities to magnify and project a 5.1-mm 2 area onto a 177.8-mm 2 screen with the image data points addressable in a 512 by 480 line matrix. The image analysis software determines component presence based on data point brightness. The CVS can verify beam lead device and crossover presences on a typical H M C in fewer than 30 s. The part identification of any missing part is printed as
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Concepts for calculating frequency of system failure. C. SINGH and A. D. PATTON. IEEE Trans. Reliab. R-29 (4), 336 (October 1980). This paper presents a frequency-balance concept which is more general than that for disjoint subsets, and describes recursive relationships for the frequency of a union of subsets or events.
an aid to rework. The CVS has reduced the time needed for component verification and has improved verification accuracy.
Low-field time-dependent dielectric integrity. EUGENE S. ANOLICK and GLENN R. NELSON. IEEE Trans. Reliab. R-29 (3), 217 (August 1980). A major contributor to reliability failures in integrated circuits has been the failure of dielectrics under operating stress. This paper surnmarizes extensive studies carried out on many manifestations of dielectric integrity failure. The outcome is a single model used to predict failure from data obtained in accelerated testing. The model contains the effect of temperature and applied voltage on the tendency to fail as well as the breakdown of the region subject to stress.
Voltage breakdown testing of relays in the 100-V range. EOIN W. GRAY and THOMAS A. UHRIG. IEEE Tran6. Components, Hybrids MJh9 Technol. C H M T - 3 (3). 442 (September 1980). The ac voltage breakdown between adjacent conductors separated by an insulator on relays has been examined using two types of breakdown test sets and a sensitive corona (partial discharget detector. A large difference in the breakdown voltages was observed on relays from the same population using two breakdown test sets. The characteristics of the test sets were examined to identify the cause of the breakdown difference. The breakdown voltage is independent of the voltage ramp speed from 55 to 8300V/s. It is also independent of the series resistance up to 300k~. The different detector systems do not contribute to the breakdown difference. The output capacitance of the breakdown test sets appears to be quite important to the voltage breakdown of the samples. Modification of the output of the test sets leads to similar breakdown valves. The prebreakdown discharges observed using the corona detector suggests that breakdown is a gas breakdown type. Effects on the insulator surfaces caused by the testing are considered in light of the prebreakdown discharge measurements and are expected to be minimal. These results should be applicable to the moderately high voltage testing of other products, although the numerical values will probably differ.
MAINTENANCE
AND
REDUNDANCY
might be useful for some reliability optimization procedures and other applications.
Reliability of all possible series-parallel redundant structures of M.I.I.D. units with two failure modes. YuJt NAKAGAWA and YOSHIO HATTORI. IEEE Trans. Reliab. R-29 (4), 320
An algebraic technique for reliability evaluation. R. K. TIWARI and MIKKt VERMA. IEEE Trans. Reliab. R-29 (4), 311 (October 1980). An algebraic technique is proposed to obtain a simplified reliability expression of a general system. A success expression which directly gives the reliability expression, is formed and simplified by the procedure. The technique is equally efficient for simple and complex systems; yields computationally efficient reliability expressions; is routine (no decision making); yields an expression having a m i n i m u m number of product terms; and is easier than many existing techniques.
(October 1980). The paper presents a method for generating systematically and exactly all possible series-parallel (s-p) structures for several i.i.d, units. The method, is modified in order to calculate the failure probabilities and reliabilities of all the possible s-p redundant structures for the i.i.d, units with two failure modes. Included is an example of finding an optimal s-p redundant structure subject to four constraints for reliability (two for failure probabilities and two for fail-safe).
Synthesis and number of all series-parallel structures with n components. WINFRID G. SCHNEEWEISS and KLAUS D. HEIDTMANN. IEEE Trans. Reliab. R-29 (4), 315 (October
"Quality" is defined as degree of conformance of an item with reference to its intended use. This includes the time factors from its design to disposal characteristic of a product from womb to tomb. In this paper several aspects of a quality product in respect of avionic equipment are considered during the various stages from design, development, testing, production, transportability, uses and ease of maintenance till an item is discarded after declaring it as obsolete.
1980). A synthesis procedure a n d - - a s a by-product--the number of different redundant structures for series-parallel systems with n components is derived. The reliability graphs of these structures, especially their fault trees, are branched like true rooted trees in the sense of graph theory. The results
Quality and reliability of avionic equipment. R. SOIvlASUNDARAM and R. S. YADAV. The QR JI {India) p. 73 (May 1980).