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Reliability definitions
200
WORLD
ABSTRACTS
ON MICROELECTRONICS
digital circuits, particularly integrated circuits, LSI and circuit packs, where masking of faults can occur, resulting in acceptance of defective items. However, it has been developed in a general manner and can be used whenever a decision has to be made regarding the introduction (or removal) of a test or inspection. It is applicable to all forms of tests, i.e. electrical, mechanical or visual, including screening or burn-in tests. The maximum allowable cost (and the worth of the test) is calculated in terms of the proportion defective in the lot, probabilities of accepting or rejecting good and bad items and the costs associated with accepted or rejected items.
o f a u t o m a t i c testing. (Production Engineers' Handbook--Part I.) Electronic Production, The economics
November (1972), p. 15. It is clear from a consideration of the many papers written over the past 2 yr on Automatic Test Equipment that the technology is still in the embryo stage that characterized the computer industry some 15 yr ago. Two important points have emerged from a study of A T E applications: The application of A T E methods should be a matter of overall policy and not be based on simply a local technical justification. In general manufacturers of A T E equipment are uninformed on the applications of their new products, and the implications of these applications in specific user environments. This does not mean to say they cannot recommend a plethora of users for their equipment, that is their purpose in life. This statement should be qualified since the applications and significance of the mini equipment are fairly self evident.
R e l i a b i l i t y definitions. H. REICHE. Microelectron. & Reliab. 11 (1972), p. 425. There are a number of documents in the U.S.A., United Kingdom and Canada which either include a list of definitions or which are specially written in the form of definition standards. It matters less which of these documents you may wish to examine and compare: of all terms defined, about 60 per cent of the definitions in one differ from those in the next one. The differences in definitions may be minor (a single word added or left out or altered), but the meaning of the definition may vary considerably from one case to the next. You may say that our standard dictionaries, Webster, Oxford, etc., should be used as the basis for any definition that no question of interpretation will arise. Unfortunately, such standards are not geared to the technical jargon which prevails among groups such as the reliability engineer. Even technical dictionaries are unable to keep abreast with the ever-changing science of reliability. Because reliability engineering covers such a wide field, it is not surprising that eaeh group of engineers wishes to express the terms in the most suitable form to fit his specialized requirement. For example, a reliability engineer concerned with development will want to model his definitions to meet his particular needs. Another reliability engineer concerned with logistics will try to define the same term differently so that it relates to his peeuliar operation. Standardization is therefore subjective to the individual need of the various specialists in the field of reliability.
AND RELIABILITY
E m i s s i o n o f v a p o u r s f r o m plastic m a t e r i a l s . P. D. PARR and M. M. S. GICK, Proceedings, Internepcon 1972, Brighton, 17-19 October (1972), p. 263. The hazards surrounding the use of polymeric materials in electrical and electronic equipments have not yet been fully evaluated. Equipment failures and, in one case, a midair explosion have occurred, where the cause has been found to be the thermal degradation of a polymeric material. Some of the problems that have been encountered are as follows: (1) intermittent contact at switches and excessive wear of brushes and bearings caused by migration of silicone based resins; (2) corrosion of metal parts by PVC and P T F E insulants, both of which evolve small quantities of acidic components well below their normally accepted maximum operating temperature; (3) corrosion caused by the breakdown products of alkyd-based paint systems; (4) instability of palladium/ palladium oxide resistors caused by reduction induced by amine cured resin systems; (5) incompatibility of encapsulants with substrates due to large differences m the thermal expansion coefficients of the materials concerned; (6) incompatibility of resin systems with one another, e.g. the inhibition of curing of certain silicone resins caused by amine cured epoxides that have not fully reacted; (7) failure of the enamel coating of wire, leading to short circuiting. E X A C T - - t h e i n t e r n a t i o n a l s y s t e m for e x c h a n g e o f i n f o r m a t i o n o n e l e c t r o n i c c o m p o n e n t s . T. GUSSING. Electron. Comp., December (1972), p. 1157. In a previous article in Electronic Components, July 1966, under the title " T h e Need for International Exchange of Reliability Data" the author discussed the establishment of an international system for the exchange of data on electronic components. Since then a worldwide system for this purpose under the name of " E X A C T " has been established and is now under full operation. This article discusses the formation of " E X A C T " , its organization and present activities as well as the experience gained. * M a t e r i a l s a n d p r o c e s s e s for e l e c t r o n d e v i c e s . National Materials Advisory Board, U.S.A. 5. 1972. MNAB-289. DA-49-083-OSA-3131 FR. A survey has been made of materials and processes for solid state electronic devices. Problem areas have been identified; various solutions have been considered; recommendations have been made. The approach has been to search for areas of materials and process innovation needed by the government based on the following criteria of effectiveness: adaptability; service effectiveness through basic understanding, batch processing, and partitionability. T h e following material areas have been addressed : elemental semiconductors; compound and alloy semiconductors; magnetics; composite structures; inorganic dielectric materials; organic dielectrics. Conclusions and recommendations were made on approaches for materials; processes, devices; structures; system applications for short term development (less than 5 yr); medium terra applied research (5-10 yr); and long term basic research (more than 10 yr).
WORLD
ABSTRACTS
ON MICROELECTRONICS
digital circuits, particularly integrated circuits, LSI and circuit packs, where masking of faults can occur, resulting in acceptance of defective items. However, it has been developed in a general manner and can be used whenever a decision has to be made regarding the introduction (or removal) of a test or inspection. It is applicable to all forms of tests, i.e. electrical, mechanical or visual, including screening or burn-in tests. The maximum allowable cost (and the worth of the test) is calculated in terms of the proportion defective in the lot, probabilities of accepting or rejecting good and bad items and the costs associated with accepted or rejected items.
o f a u t o m a t i c testing. (Production Engineers' Handbook--Part I.) Electronic Production, The economics
November (1972), p. 15. It is clear from a consideration of the many papers written over the past 2 yr on Automatic Test Equipment that the technology is still in the embryo stage that characterized the computer industry some 15 yr ago. Two important points have emerged from a study of A T E applications: The application of A T E methods should be a matter of overall policy and not be based on simply a local technical justification. In general manufacturers of A T E equipment are uninformed on the applications of their new products, and the implications of these applications in specific user environments. This does not mean to say they cannot recommend a plethora of users for their equipment, that is their purpose in life. This statement should be qualified since the applications and significance of the mini equipment are fairly self evident.
R e l i a b i l i t y definitions. H. REICHE. Microelectron. & Reliab. 11 (1972), p. 425. There are a number of documents in the U.S.A., United Kingdom and Canada which either include a list of definitions or which are specially written in the form of definition standards. It matters less which of these documents you may wish to examine and compare: of all terms defined, about 60 per cent of the definitions in one differ from those in the next one. The differences in definitions may be minor (a single word added or left out or altered), but the meaning of the definition may vary considerably from one case to the next. You may say that our standard dictionaries, Webster, Oxford, etc., should be used as the basis for any definition that no question of interpretation will arise. Unfortunately, such standards are not geared to the technical jargon which prevails among groups such as the reliability engineer. Even technical dictionaries are unable to keep abreast with the ever-changing science of reliability. Because reliability engineering covers such a wide field, it is not surprising that eaeh group of engineers wishes to express the terms in the most suitable form to fit his specialized requirement. For example, a reliability engineer concerned with development will want to model his definitions to meet his particular needs. Another reliability engineer concerned with logistics will try to define the same term differently so that it relates to his peeuliar operation. Standardization is therefore subjective to the individual need of the various specialists in the field of reliability.
AND RELIABILITY
E m i s s i o n o f v a p o u r s f r o m plastic m a t e r i a l s . P. D. PARR and M. M. S. GICK, Proceedings, Internepcon 1972, Brighton, 17-19 October (1972), p. 263. The hazards surrounding the use of polymeric materials in electrical and electronic equipments have not yet been fully evaluated. Equipment failures and, in one case, a midair explosion have occurred, where the cause has been found to be the thermal degradation of a polymeric material. Some of the problems that have been encountered are as follows: (1) intermittent contact at switches and excessive wear of brushes and bearings caused by migration of silicone based resins; (2) corrosion of metal parts by PVC and P T F E insulants, both of which evolve small quantities of acidic components well below their normally accepted maximum operating temperature; (3) corrosion caused by the breakdown products of alkyd-based paint systems; (4) instability of palladium/ palladium oxide resistors caused by reduction induced by amine cured resin systems; (5) incompatibility of encapsulants with substrates due to large differences m the thermal expansion coefficients of the materials concerned; (6) incompatibility of resin systems with one another, e.g. the inhibition of curing of certain silicone resins caused by amine cured epoxides that have not fully reacted; (7) failure of the enamel coating of wire, leading to short circuiting. E X A C T - - t h e i n t e r n a t i o n a l s y s t e m for e x c h a n g e o f i n f o r m a t i o n o n e l e c t r o n i c c o m p o n e n t s . T. GUSSING. Electron. Comp., December (1972), p. 1157. In a previous article in Electronic Components, July 1966, under the title " T h e Need for International Exchange of Reliability Data" the author discussed the establishment of an international system for the exchange of data on electronic components. Since then a worldwide system for this purpose under the name of " E X A C T " has been established and is now under full operation. This article discusses the formation of " E X A C T " , its organization and present activities as well as the experience gained. * M a t e r i a l s a n d p r o c e s s e s for e l e c t r o n d e v i c e s . National Materials Advisory Board, U.S.A. 5. 1972. MNAB-289. DA-49-083-OSA-3131 FR. A survey has been made of materials and processes for solid state electronic devices. Problem areas have been identified; various solutions have been considered; recommendations have been made. The approach has been to search for areas of materials and process innovation needed by the government based on the following criteria of effectiveness: adaptability; service effectiveness through basic understanding, batch processing, and partitionability. T h e following material areas have been addressed : elemental semiconductors; compound and alloy semiconductors; magnetics; composite structures; inorganic dielectric materials; organic dielectrics. Conclusions and recommendations were made on approaches for materials; processes, devices; structures; system applications for short term development (less than 5 yr); medium terra applied research (5-10 yr); and long term basic research (more than 10 yr).