Pub Date : 1900-01-01DOI: 10.1109/HOLM.1991.170829
T. Imrell
The deterioration mechanisms of unplated and silver-plated copper contacts subjected to corrosive environments have been studied. The influence of the surface treatment and the silver coating thickness was investigated in a short-time test in a flowing mixture of three gases. The influence of brighteners and chromate passivation of the silver coating was also studied. In addition to contact resistance measurements at different normal loads, Auger electron microscopy was used to study the processes involved. Short-time testing in a flowing mixture of three gases proved to be a valuable means for investigating the performance of electrical contacts. It is concluded that the silver coating thickness is the most important factor in corrosion resistance. Contacts with a thin silver coating behave almost like ground unplated copper contacts.<>
{"title":"The importance of the thickness of silver coating in the corrosion behaviour of copper contacts","authors":"T. Imrell","doi":"10.1109/HOLM.1991.170829","DOIUrl":"https://doi.org/10.1109/HOLM.1991.170829","url":null,"abstract":"The deterioration mechanisms of unplated and silver-plated copper contacts subjected to corrosive environments have been studied. The influence of the surface treatment and the silver coating thickness was investigated in a short-time test in a flowing mixture of three gases. The influence of brighteners and chromate passivation of the silver coating was also studied. In addition to contact resistance measurements at different normal loads, Auger electron microscopy was used to study the processes involved. Short-time testing in a flowing mixture of three gases proved to be a valuable means for investigating the performance of electrical contacts. It is concluded that the silver coating thickness is the most important factor in corrosion resistance. Contacts with a thin silver coating behave almost like ground unplated copper contacts.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"234 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115756045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1991.170809
W. Rieder, T. Strof
The influence of the electrical stress on the contact resistance behavior of several signal and power relays has been investigated during life tests comprising 2 million operations. The results obtained with the aid of a specially developed test device showed characteristic contact resistance patterns for different electrical loads, contact materials, and designs. Under certain load conditions the contact resistance is increased by carbon deposits while both lower and higher loads caused lower contact resistance values.<>
{"title":"Reliability of commercial relays during life tests with intermediate or low power contact load","authors":"W. Rieder, T. Strof","doi":"10.1109/HOLM.1991.170809","DOIUrl":"https://doi.org/10.1109/HOLM.1991.170809","url":null,"abstract":"The influence of the electrical stress on the contact resistance behavior of several signal and power relays has been investigated during life tests comprising 2 million operations. The results obtained with the aid of a specially developed test device showed characteristic contact resistance patterns for different electrical loads, contact materials, and designs. Under certain load conditions the contact resistance is increased by carbon deposits while both lower and higher loads caused lower contact resistance values.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115841238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1991.170823
G. Kulwanoski, M. Gaynes, A. Smith, B. Darrow
The most common failure mechanisms for electrical contacts are classified, defined, and discussed. Time- and temperature-dependent mechanisms include metallurgical diffusion, surface migration, evaporation, decomposition, outgassing, stress relaxation, and creep. Concentration gradients and mechanical loads also affect the rate of these mechanisms. Other mechanisms are induced from a mismatch in coefficient of thermal expansion and are triggered by thermal cycling. Corrosion mechanisms result from corrosive gases and particulates. Wear mechanisms result from motion at interfaces. Mechanical failures occur from structural defects and foreign particulate contamination. Various parameters influence these failure mechanisms. The ultimate single effect is a degradation of the contact interface resulting in high contact resistance, an open, or an intermittent open. It is concluded that, with sound understanding, these failure mechanisms and their undesirable effects can be avoided by appropriate connector design or selection, implementation, and quality control.<>
{"title":"Electrical contact failure mechanisms relevant to electronic packages","authors":"G. Kulwanoski, M. Gaynes, A. Smith, B. Darrow","doi":"10.1109/HOLM.1991.170823","DOIUrl":"https://doi.org/10.1109/HOLM.1991.170823","url":null,"abstract":"The most common failure mechanisms for electrical contacts are classified, defined, and discussed. Time- and temperature-dependent mechanisms include metallurgical diffusion, surface migration, evaporation, decomposition, outgassing, stress relaxation, and creep. Concentration gradients and mechanical loads also affect the rate of these mechanisms. Other mechanisms are induced from a mismatch in coefficient of thermal expansion and are triggered by thermal cycling. Corrosion mechanisms result from corrosive gases and particulates. Wear mechanisms result from motion at interfaces. Mechanical failures occur from structural defects and foreign particulate contamination. Various parameters influence these failure mechanisms. The ultimate single effect is a degradation of the contact interface resulting in high contact resistance, an open, or an intermittent open. It is concluded that, with sound understanding, these failure mechanisms and their undesirable effects can be avoided by appropriate connector design or selection, implementation, and quality control.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130898884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1991.170819
K. Sawa, N. Shimoda
Many small DC motors are used for automotive electrical equipment. In particular, motors for fuel pumps play the important role of supplying the engine with gasoline. In these motors commutation is done in gasoline. A new test apparatus has been developed for the investigation of commutation phenomena in gasoline. The duration of the commutation arc in gasoline was found to be shorter by about 30 approximately 50% than in air, in cases of both Cu and Ag/Ni. The value of the residual current of commutation in gasoline is generally smaller than in air. The arc duration is proportional to the residual current, and the slope in gasoline is smaller than in air. It is caused by the difference of the arc voltage. The carbon adhesion on the commutator surface in gasoline is much less than in air.<>
{"title":"A study of commutation arc of DC motor for automotive fuel pump","authors":"K. Sawa, N. Shimoda","doi":"10.1109/HOLM.1991.170819","DOIUrl":"https://doi.org/10.1109/HOLM.1991.170819","url":null,"abstract":"Many small DC motors are used for automotive electrical equipment. In particular, motors for fuel pumps play the important role of supplying the engine with gasoline. In these motors commutation is done in gasoline. A new test apparatus has been developed for the investigation of commutation phenomena in gasoline. The duration of the commutation arc in gasoline was found to be shorter by about 30 approximately 50% than in air, in cases of both Cu and Ag/Ni. The value of the residual current of commutation in gasoline is generally smaller than in air. The arc duration is proportional to the residual current, and the slope in gasoline is smaller than in air. It is caused by the difference of the arc voltage. The carbon adhesion on the commutator surface in gasoline is much less than in air.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117199114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A possibility of reducing contact material requirements in relays by application of hollow contact rivets was investigated. In the current type of relays, standard massive contacts were replaced by specially prepared hollow contacts, shaped in the form of shells made of a thin plate of contact material. The results of contact performances of hollow and massive contact rivets, applied in the same type of relays for tests, were compared. Evaluation of bouncing, temperature rise on contacts, arc duration at break, switching capacity, and electric contact life was performed according to IEC standards. Good or even better performances of hollow contacts were obtained. After tests some microscopic examinations of contact surfaces were performed which indicate erosion characteristics at higher electrical loads.<>
{"title":"Switching performances of hollow contact rivets","authors":"P. Žunko, M. Bizjak","doi":"10.1109/33.142895","DOIUrl":"https://doi.org/10.1109/33.142895","url":null,"abstract":"A possibility of reducing contact material requirements in relays by application of hollow contact rivets was investigated. In the current type of relays, standard massive contacts were replaced by specially prepared hollow contacts, shaped in the form of shells made of a thin plate of contact material. The results of contact performances of hollow and massive contact rivets, applied in the same type of relays for tests, were compared. Evaluation of bouncing, temperature rise on contacts, arc duration at break, switching capacity, and electric contact life was performed according to IEC standards. Good or even better performances of hollow contacts were obtained. After tests some microscopic examinations of contact surfaces were performed which indicate erosion characteristics at higher electrical loads.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134528417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Compares the contact resistance, welding, and erosion of three basic contact materials suitable in automotive DC relays for switching lamp, motor, and resistor loads. The three contact materials chosen have different material strengthening mechanisms so that their effects on the arc erosion process could be evaluated. They were a silver alloy (98Ag-2Cu), a metal-oxide composite (Ag-SnO/sub 2/ with WO/sub 3/ additive), and a metal-metal composite (Ag-20Ni). Contact resistance, welding, and DC transfer characteristics were compared in make-only, break-only, and normal make-and-break switching operations. The results were explained in terms of the arc erosion process and inherent material structures. All three types of contact material have their pros and cons in automotive applications.<>
{"title":"Electric contact materials and their erosion in automotive DC relays","authors":"C. Leung, A. Lee","doi":"10.1109/33.142887","DOIUrl":"https://doi.org/10.1109/33.142887","url":null,"abstract":"Compares the contact resistance, welding, and erosion of three basic contact materials suitable in automotive DC relays for switching lamp, motor, and resistor loads. The three contact materials chosen have different material strengthening mechanisms so that their effects on the arc erosion process could be evaluated. They were a silver alloy (98Ag-2Cu), a metal-oxide composite (Ag-SnO/sub 2/ with WO/sub 3/ additive), and a metal-metal composite (Ag-20Ni). Contact resistance, welding, and DC transfer characteristics were compared in make-only, break-only, and normal make-and-break switching operations. The results were explained in terms of the arc erosion process and inherent material structures. All three types of contact material have their pros and cons in automotive applications.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130167130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A number of coating materials commonly used for aluminum-to-copper connections were evaluated on the basis of their effect on the contact resistance-force/torque relationships, the performance of coated joints under current-cycling and fretting conditions, and ability to protect the contact against galvanic corrosion in saline and industrially polluted environments. The results showed that the use of nickel-plating of both aluminum and copper and copper-plating of aluminum ensures the greatest stability while bare aluminum in contact with tin- and silver-plated copper shows the poorest performance under different operating conditions.<>
{"title":"Evaluation of different platings for aluminum-to-copper connections","authors":"M. Braunovic","doi":"10.1109/33.142896","DOIUrl":"https://doi.org/10.1109/33.142896","url":null,"abstract":"A number of coating materials commonly used for aluminum-to-copper connections were evaluated on the basis of their effect on the contact resistance-force/torque relationships, the performance of coated joints under current-cycling and fretting conditions, and ability to protect the contact against galvanic corrosion in saline and industrially polluted environments. The results showed that the use of nickel-plating of both aluminum and copper and copper-plating of aluminum ensures the greatest stability while bare aluminum in contact with tin- and silver-plated copper shows the poorest performance under different operating conditions.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"190 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121092432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1991.170804
S. Kharin
A mathematical model describing interdependent transient temperature and electromagnetic fields in electrical contacts at three stages of pre-arcing of opening of contact (closed, initial opening, and bridging) is discussed. The dynamics of temperature change and its dependence on the contact films, and Thomson, Kohler, and Peltier effects are described. It is shown that nonuniform current density in the contact spot over the frequency range of 0-10 Hz is enhanced by current constriction rather than by the skin-effect. The relationships between the rate of appearance of the extra forces in contacts during the opening period are established. The model of thermal explosion is invoked to explain the mechanism of spontaneous separation of contact resulting from the combined action of electrodynamic and thermal forces generated by the explosive evaporation of material at high current. The model was used to describe the bridging stage of contact opening. It is established that the shape of the bridge, its temperature field, and the lifetime mechanism of rupture are determined by the dynamics of contact opening and also forces resulting from the surface tension, the pinch effect, and Joule, Thomson, and tunnel heating.<>
{"title":"Transient thermophysical phenomena at the pre-arcing period during opening of electrical contacts","authors":"S. Kharin","doi":"10.1109/HOLM.1991.170804","DOIUrl":"https://doi.org/10.1109/HOLM.1991.170804","url":null,"abstract":"A mathematical model describing interdependent transient temperature and electromagnetic fields in electrical contacts at three stages of pre-arcing of opening of contact (closed, initial opening, and bridging) is discussed. The dynamics of temperature change and its dependence on the contact films, and Thomson, Kohler, and Peltier effects are described. It is shown that nonuniform current density in the contact spot over the frequency range of 0-10 Hz is enhanced by current constriction rather than by the skin-effect. The relationships between the rate of appearance of the extra forces in contacts during the opening period are established. The model of thermal explosion is invoked to explain the mechanism of spontaneous separation of contact resulting from the combined action of electrodynamic and thermal forces generated by the explosive evaporation of material at high current. The model was used to describe the bridging stage of contact opening. It is established that the shape of the bridge, its temperature field, and the lifetime mechanism of rupture are determined by the dynamics of contact opening and also forces resulting from the surface tension, the pinch effect, and Joule, Thomson, and tunnel heating.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129886057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1991.170821
Zhuan-Ke Chen
The impact effect on electrical contact of dry reed relay has been investigated with scanning electron microscopy (SEM), X-ray fluorescence (EDX), and Auger electron spectroscopy (AES) analytical systems. On the basis of experiments, it has been recognized that mechanical impact was a serious problem for this kind of relay contact, SEM, EDX, and AES analysis revealed that considerable damage of the contact zones resulted from the impact action and substantial exchange of material occurred. The contact resistance varied with increase of impact numbers. The results showed that impact action can lead to impact wear, resistance failure, or failures to release (sometimes called sticking) after a relatively small number of operations. A model of impact action was proposed and tested. It was also used to study the processes involved in impacting.<>
{"title":"Impact wear of electric contact","authors":"Zhuan-Ke Chen","doi":"10.1109/HOLM.1991.170821","DOIUrl":"https://doi.org/10.1109/HOLM.1991.170821","url":null,"abstract":"The impact effect on electrical contact of dry reed relay has been investigated with scanning electron microscopy (SEM), X-ray fluorescence (EDX), and Auger electron spectroscopy (AES) analytical systems. On the basis of experiments, it has been recognized that mechanical impact was a serious problem for this kind of relay contact, SEM, EDX, and AES analysis revealed that considerable damage of the contact zones resulted from the impact action and substantial exchange of material occurred. The contact resistance varied with increase of impact numbers. The results showed that impact action can lead to impact wear, resistance failure, or failures to release (sometimes called sticking) after a relatively small number of operations. A model of impact action was proposed and tested. It was also used to study the processes involved in impacting.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125325272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The increase of contact resistance is calculated for brush contact on a slipring, segmented into a sequence of rectangular contact patches, evenly spaced. This approximates the condition of liquid-metal-wetted brushes where uniform contact may occur over the rectangular brush footprint. A Fourier series expansion shows that for wide spacing of the footprints a component of resistance arises from the fact that the current input is segmented. The resistance is mainly dependent upon the logarithm of spacing. As the separation becomes narrower than the contact bands, there is a drop in the segmentation component of resistance.<>
{"title":"Interaction of multiple brushes on a slipring","authors":"R. A. Burton, R. G. Burton","doi":"10.1109/33.148499","DOIUrl":"https://doi.org/10.1109/33.148499","url":null,"abstract":"The increase of contact resistance is calculated for brush contact on a slipring, segmented into a sequence of rectangular contact patches, evenly spaced. This approximates the condition of liquid-metal-wetted brushes where uniform contact may occur over the rectangular brush footprint. A Fourier series expansion shows that for wide spacing of the footprints a component of resistance arises from the fact that the current input is segmented. The resistance is mainly dependent upon the logarithm of spacing. As the separation becomes narrower than the contact bands, there is a drop in the segmentation component of resistance.<<ETX>>","PeriodicalId":368900,"journal":{"name":"Electrical Contacts - 1991 Proceedings of the Thirty-Seventh IEEE HOLM Conference on Electrical Contacts","volume":"260 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122756116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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