This study is aimed at clarifying the mechanism of wear process for Ag plating. The samples of different hardness Ag plating on copper alloys were prepared as coupon and embossment specimens, which simulated terminal contacts. During the sliding test, the contact resistance and the friction coefficient versus sliding distance are measured. The surface observation and surface roughness of the Ag films after wear tests were investigated. As results, the hard Ag plating film (120 Hv) exhibited higher contact resistance comparing to the soft Ag plating film (80 Hv). The soft Ag film delivered wider wear trace on coupon specimens compared to the hard one. Moreover, the observation of tribofilms formed on the Ag films after wear tests suggested that a mixed-type of adhesive and abrasive wears occurred for both of soft and hard Ag films. Furthermore, the fretting corrosion resistance of Ag plating samples with different hardness was also investigated. As results, the wear resistance of hard Ag film was stronger than that of soft Ag film.

Since electromagnetic (EM) noise resulting from an arc discharge disturbs other electric devices, parameters on electromagnetic compatibility, as well as lifetime and reliability, are important properties for electrical contacts. To clarify the characteristics and the mechanism of the generation of the EM noise, the arc column and voltage fluctuations generated by slowly breaking contacts with external direct current (DC) magnetic field, up to 20,mT, was investigated experimentally using Ag$_{90.7{ m wt%}}$SnO$_{2,9.3{ m wt}%}$ material. Firstly the motion of the arc column is measured by high-speed camera. Secondary, the distribution of the motion of the arc and contact voltage are discussed. It was revealed that the contact voltage fluctuation in the arc duration is related to the arc column motion.

Arc discharge at breaking electrical contact is considered as a main source of not only degradation of the electrical property but also an undesired electromagnetic (EM) noise. In order to clarify the effect of holder temperature on the bridge and arc-duration, opening-waveforms at slowly separating silver-tin dioxide contact with different holder temperature are measured and discussed experimentally in this paper. Firstly, as opening-waveforms, the contact voltage, the contact current and the movement of moving contact related to the gap length are measured simultaneously. Secondly, the relationship between temperature of the holder and duration of the arc was quantified experimentally. It was revealed that as the initial temperature of the holder becomes higher, arc-duration becomes slightly longer. More importantly, the holder temperature dependencies of percentage of each-phase (metallic and gaseous-phases) are different with different closed-current.

Arc discharge generated by breaking electrical contact is considered as a main source of not only degradation of the electrical property but also an undesired electromagnetic (EM) noise. In order to clarify the effect of heated temperature on the bridge, arc-duration and the fluctuation of voltage, opening-waveforms at slowly separating silver-tin dioxide contact with holder heating are measured and discussed experimentally in this paper. Firstly, opening-waveforms are measured. Secondly, voltage fluctuation of the each arc-phase is discussed to extract the effect of the heated holder. The relationship between temperature of the heated holder and duration and fluctuation of the arc was investigated experimentally. It was revealed that as the initial temperature of the heated holder becomes higher, arc-duration becomes slightly longer. In addition, voltage fluctuation at the gaseous-phase decreases when the holder is heated. Consequently, the heated holder can suppress the voltage fluctuation even if its duration becomes slightly longer.

Using a self-developed ASTM test system of contact material electrical properties under low voltage (LV), small-capacity, the current-frequency variable and a photoelectric analytical balance, the electric performance comparison experiments and material weighing of silver-based electrical contact materials, such as silver/tungsten and silver/cadmium oxide contact materials, are completed under LV, pure resistive load and small current at 400 Hz/50 Hz. The surface profiles and constituents of silver/tungsten contact material were observed and analyzed by SEM and EDAX. Researches indicate that the form of the contact material arc burnout at 400 Hz is stasis, not an eddy flow style at 50 Hz; meanwhile, the area of the contact burnout at 400 Hz is less than that of 50 Hz, and the local ablation on the surface layer at 400 Hz is more serious. Comparing the capacities of the silver-based contact materials with different second element such as CAgW50, CAgNi10, CAgC4 and CAgCdO15 at 400 Hz, no matter what the performances of arc erosion resistance or welding resistance, it can be found that the capacities of the silver/tungsten material is the best.

This paper proposes a printed tag antenna for the universal ultra-high frequency (UHF) radio frequency identification (RFID) band (860-960 MHz) using the R2R process. To widen impedance bandwidth, a π-shaped matching network is suggested. The overall dimension of the proposed tag antenna is 83.4 mm 30.2 mm and it has a gain of over 1 dBi for the entire UHF RFID band. The performances of the proposed tag antenna, printed with conductivity silver ink using an R2R process, are compared with those of a copper antenna.

In prior work, contact welding phenomena were observed in automotive relays during break of motor inrush current. The switching performance of the type of relay investigated could be correlated with the parameters: over-travel, coil suppression, and the break current. In the present work the author further explores the impact of both the contact material (silver tin oxide versus fine grain silver) and the contact surface topography (brand new and pre-aged contacts). He further assesses the robustness of the system "relay" with those parameters using the Taguchi methods for robust design. Furthermore, the robustness of two alternative automotive relay types will be discussed.

Electromechanical switching devices such as relays may be surprisingly forgiving to occasional, but temporary, electrical stress beyond specification. Consequently delayed openings due to welded contacts on the order of milliseconds usually have been unnoticed and hence have not been reason for concern. However, as electrical systems of vehicles are getting "smarter" and more and more diagnostic routines are being implemented, even such short delay times may be translated as errors. Pre-conditioning contact surfaces has been explored as a measure to increase the welding resistance and eliminate contact opening delays. The 20-A-class relay investigated has been optimized to break occasional current peaks up to 80 ADC.

In this paper, a method of separating the effects of the thermal diffusivity, durations and integral powers of the bridge and arc on the temperature rise of AgPd contacts was proposed. First, the effects of the Pd content on the durations and integral powers of the bridge and arc, and the temperature rise of the contacts were discussed. Because the integral power of bridge was larger than that of the arc under our experimental conditions of 40 V open-circuit, 5 A close-circuit and 100 µm/s opening velocity, the temperature rise of the contacts was dominated by the bridge. No remarked difference in bridge duration can be seen among the six materials. Although the integral power of the bridge in the case of Pd was maximum, the maximum temperature rise of the contact was observed in the case of AgPd60. To clarify the contribution of each factor, the effect of thermal diffusivity on the temperature rise of the contact was evaluated by the finite-difference time-domain (FDTD) method. In the case of Pd, because its thermal diffusivity was largest, heat diffused rapidly. On the other hand, the thermal diffusivity in the case of AgPd60 was small, and heat diffused slowly to the holders. The maximum temperature rise was observed in the case of AgPd60. It was demonstrated that the proposed method of separating the effects of thermal diffusivity, durations and integral powers of the bridge and arc on the temperature rise of contacts is effective in enabling us to understand contact phenomena.

Sticking is one of dominant characteristics of reliability in relays for medium current loads from several amperes to several dozen amperes, which are used for relays for automobiles, industrial control units or power supplies of household electrical appliances. Correlations between the release failures due to sticking and contact characteristics such as arc discharges, material parameters and design factors in relays have never been always made clear. This puts difficulty in the way of reasonable development of contact materials and rational design of relays. So, dependence of electrical load conditions on sticking characteristics are investigated, using the Ag-CdO contacts which have had high practical use to relays for medium current loads. Furthermore, relationship among the sticking characteristics, arc discharge characteristics and contact surface properties after operations are studied. Mechanism of sticking is considered on the basis of those data. The results are as follows: (1) Sticking phenomenon occurs intermittently from initial operations and lasts to the end. (2) The µ + 2 σ value (the sum of the mean value and the integral multiple of the standard deviation of sticking force) increases in proportion to the circuit current. On the other hand, it has the maximum value at a circuit voltage, slightly less than the minimum arc voltage. (3) Factors causing the sticking are considered to be divided into direct factors and its root factors. It is considered that a dominant direct factor is welding, and that its root factor is bridge or welding by Joule's heat. On the other hand, the sticking force becomes rather lower as the circuit voltage increases, in the circuit voltage range where regular arc discharge occurs.

In a DC 50 V/3.3 A circuit, the spatial distributions of the spectral intensities of breaking arcs near the cathode for silver contacts were measured on the contact surfaces of three different shapes: flat and spherical (1 mm radius and 2 mm radius) and the arc temperature and the metal-vapor quantity were calculated from the spectral intensities. The influence of the contact shape on the arc temperature and the metal-vapor quantity were also examined, as well as the arc tracks on the contact surfaces and the gain and loss of the contacts. Findings show the distributions of spectral intensities are non-symmetrical from the beginning to the extinction of the breaking arc for the flat contact: However, they are symmetrical in the latter half of the breaking in spite of the number of breaking arcs and the shape of contact surface for the spherical contact. The relationship between the area of the arc tracks on the cathode and the shape of contact surface is the same as the relationship between the existent areas of measured spectra and the shape of the contact surface. For the spherical contacts, the arc temperature and the metal-vapor quantity are affected a little by the radius of the curved of contact surface and the number of breaking arcs. However, the longer the arc duration, the higher the metal-vapor quantity is in the latter period of the breaking arc. For the flat contacts, the metal-vapor quantity is lower than those for the spherical contacts. The gain and loss of the contacts are less and the arc duration is shorter for the flat contact than for the spherical contact.

The distributions of a spectral intensity of the breaking arc between silver contacts in DC 45-66 V/2.5-5.0 A circuits have been measured using a high-speed color video. As a result, a cathode brightening spot, which has a high spectral intensity, exists near the cathode surface. The cathode brightening spot expands with the increase of the contact gap, but its length expands until about 18µm. When the contact gap spreads over about 180 µm, a dark positive column appears and grows between the cathode brightening spot and the anode surface. The higher the interrupted current is, the larger the diameter of the cathode brightening spot will be. The maximum diameter of cathode brightening spot is 500 µm under these experiments.

Silver is a fundamental material for electrical contact application. In spite of high electrical conductivity and economical advantage, silver surface is corroded easily by environment contained sulfide. A corrosion product as Ag2S deteriorates the property of contact reliability. In order to examine contact reliability, the acceleration tests have been accepted widely in industries. In the present study, the acceleration factor of the contact reliability for the sulfide film on the surface of silver contact which was subject to the tarnish acceleration test was clarified in comparison with the film grown in a normal office environment. The accelerated environment based on the Japan Electric Industry Development Association (JEIDA) standard No.25 was adopted. This environment is consisted of air contained 3 ppm H2S gas under 40, 85-95% RH. The growth rate of the sulfide film (Ag2S) was evaluated by applying the ellipsometry analysis. In the results, it was found that growth of Ag2S film of 500 in thickness in the normal office environment required corrosion time of 3103 h. This thickness of 500 caused increase in contact resistance of 0.1-1.0 (Ω). However, in the accelerated environment, corrosion time decreased to 1.7 h for same thickness. Therefore, the acceleration factor was obtained by comparison of these time as 1.8103 for the standard test of JEIDA.

The authors have studied mechanism of transition from metallic phase to gaseous phase in contact break arc. For further elucidation of the mechanism, we have carried out spectroscopic measurement. The spectrum measurement system which had high time resolution was composed using two monochromators and a bifurcated image fiber, which had one input port and two output ports. The input port received the arc light, and the two monochromators received the arc light from the two output ports, respectively. The spectral sensitivity of the two monochromators was corrected with a standard lamp. We have measured simultaneously two spectra of break arc for Ag in laboratory air, under the condition where source voltage E=48 V, load inductance L=2.3 mH, and closed contact current I0=6 A. As a result, the time-varying tendency of spectrum intensity is similar for the same element, even if the wavelength is different. And from the comparison of time average spectrum intensity, it is clarified that average intensity for gas spectrum does not attain to 10% of that for metallic atomic spectrum (Ag I, 520.91 nm). In addition, the decrease point of Ag II (ion) spectrum has been found to correspond with the peak of Ag I (atom) spectrum.