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The resistance, mass transfer, erosion and arc properties of a new contact material named Ag/LaFe_1-xNi_xO₃ conductive ceramics were investigated. Ag/LaFe_1-xNi_xO₃ performed well under low voltage conditions in contrast with other contact materials such as Ag/CdO and Ag/SnO₂. After 5000 make-and-break operations, life test was made and the surface analysis method together with an arc voltage waveform was used to research the corrosion resisting and mass transfer properties. It was found that the conductive ceramics used in the contact materials could influence the resistance performance and, in turn, influence the mass transfer, erosion and arc characteristics.

We present a model to understand the effect of temperature on the electrical resistance of individual semiconducting single wall carbon nanotubes (s-SWCNTs) of various diameters under various electric fields. The temperature dependence of the resistance of s-SWCNTs and metallic SWCNTs (m-SWCNTs) are compared. These results help us to understand the temperature dependence of the resistance of SWCNTs network. We experimentally examine the temperature dependence of the resistance of random networks of SWCNTs, prepared by dispersing CNTs in ethanol and drop-casting the solution on prefabricated metallic electrodes. Examining various samples with different electrode materials and spacings, we find that the dominant resistance in determination of the temperature dependence of resistance of the network is the resistance of individual tubes, rather than the tube–tube resistance or tube–metal contact resistance. It is also found that the tube–tube resistance depends on the electrode spacing and it is more important for larger electrode spacings. By applying high electric field to burn the all-metallic paths of the SWCNTs network, the temperature dependence of the resistance of s-SWCNTs is also examined. We also investigate the effect of acid treatment of CNTs on the temperature dependence of the resistance of SWCNTs and also multi-wall CNTs (MWCNTs) networks.

A short channel organic field effect transistors (OFET) based on Pentacene, having channel length in the range of sub-micrometer, has been numerically modelled for low values of drain voltage. The output characteristics show a nonlinear concave increase of drain current for all values of gate voltages. This anomalous current-voltage behavior, which resembles sub-threshold characteristics of silicon FETs, shows a good match with earlier experimental reports on OFET at low drain voltages. The sub-threshold-like characteristics has been interpreted in light of thermionic-emission model because of the presence of hole injection barrier at drain (gold)/Pentacene interface. The associated analysis has facilitated to obtain a significant parameter, effective channel thickness $(t_{\mathrm{\text{eff}}})$, for the first time in case of OFETs. It came out to be roughly 4 nm and 8 nm for experimental devices of poly(3-hexylthiophene-2,5-diyl) and Pentacene, respectively, while the numerically modelled device yielded a value of about 60 nm. Increase of $t_{\mathrm{\text{eff}}}$ with transverse gate electric field is also observed. Physical explanation of the observations is also presented.

Low frequency noise in the indium–zinc oxide thin-film transistors (IZO TFTs) at low drain voltage is investigated in this paper. First, the contact resistance is extracted from transfer characteristics. By analyzing the noise behavior under different bias conditions, the measured noises in IZO TFTs have been separated into contributions from the channel and contacts. Determined by the channel and the contact, the normalized noise varied with two slopes ($m=-1.09$ and 2) with the increment of effective gate voltage. Moreover, the values of flat-band voltage noise spectral density and Coulomb scattering parameter have been extracted. By considering contact resistance, the normalized noise has also been modeled by the use of carrier number with the correlated mobility fluctuation $(\mathrm{\Delta }N-\mathrm{\Delta }\mu )$ model.

The fretting wear behavior of tin plated copper alloy contacts and its influence on the contact resistance are addressed in this paper. Based on the change in the area of contact zone as well as the wear depth as a function of fretting cycles, a model was proposed to explain the observed low and stable contact resistance. The extent of wear of tin coating and the formation of wear debris as a function of fretting cycles were assessed by scanning electron microscopy (SEM). Energy dispersive X-ray line scanning (EDX), X-ray mapping, and EDX spot analysis were employed to characterize the nature of changes that occur at the contact zone. The study reveals that the fretted area increases linearly up to 8000 cycles due to the continuous removal of the tin coating and attains saturation when the fretting path length reaches a maximum. The observed low and stable contact resistance observed up to 8000 cycles is due to the common area of contact which provides an electrically conducting area. Surface analysis by SEM, EDX, and X-ray elemental mapping elucidate the nature of changes that occurred at the contact zone. Based on the change in contact resistance as a function of fretting cycles, the fretting wear and fretting corrosion dominant regimes are proposed. The interdependence of extent of wear and oxidation increases the complexity of the fretting corrosion behavior of tin plated contacts.

The performance of electroless (EL) Ni–B coated brass contacts under fretting conditions was evaluated. The contact resistance of EL Ni–B coated brass contact was measured as a function of fretting cycles. The surface profile and wear depth of the fretted zone were measured using laser scanning microscope. The study reveals that EL Ni–B coated contacts exhibit better performance under fretting conditions. However, at conditions which are prone for severe oxidation such as, low frequency (3 Hz) or high temperature (155°C), EL Ni–B coated contacts fail to exhibit a better stability. The quick removal of the oxide film by fretting motion, rapid oxidation of the fresh metallic particles and trapping of the oxidation products in the remaining coating, cause the contact resistance to increase to unacceptable levels at such conditions. The study concludes that EL Ni–B coating is not a suitable choice for connector contacts that could experience fretting under highly oxidizing conditions.

Three different types of current-collecting plates for air-hydrogen PEM fuel cell were manufactured and tested: unmodified titanium plates; gold-plated titanium plates and titanium plates treated by carbon ions implantation. It was shown that the applied surface modifications reduce contact resistance between titanium plate and carbon gas diffusion layer. Total ohmic resistance of fuel cell is reduced by 1.8 and 1.4 times in case of gold-plated titanium and carbon-implanted titanium, respectively, in comparison with uncoated titanium. Although gold plating turned out to be more profitable than carbon ion implantation in terms of electrical characteristics, in the last case, the performance enhancement was reached without using precious metals, which at mass production must play more important role. This technology promises to reduce the cost of bipolar plates manufacturing, while maintaining high electrical performance of PEM fuel cells.

The resistance and noise of films prepared with poor contacts are dominated by the contact interface and for perfect contacts holds that resistance and noise stem from outside the contact interface region. The proposed test pattern to study the different contributions uses one mask. It permits two- and four-point measurements enabling the detection of a weak contribution from outside the contact interface on top of a strong interface contribution. The resistance and noise for poor and perfect contacts are calculated between pairs of circular top electrodes of equal diameters 2r at distances L with L/2r = 10. The dependences of resistance and noise on the contact diameter are quite different for perfect and poor contacts.

1/f noise of films taken from literature are compared in the noise figure of merit K = C_us [cm²]/R_sh[Ω]. K is the ratio of 1/f noise normalized for bias, frequency and unit surface to sheet resistance. Materials can be classified based on K-values. Very high K-values point to inhomogeneous electric fields on a microscopic scale (percolation conduction). The contact interface 1/f noise and specific contact resistance are characterized by C_ust [cm²] and ρ_ct [Ω cm²]. Reviews of K for films and C_ust for interfaces show that 1/f noise is a more sensitive tool than merely the resistance parameters R_sh and ρ_ct.

Single wall carbon nanotubes suspended in isopropyl alcohol are placed between two Au electrodes by ac dielectrophoresis method. Total resistance including the contact resistance and intrinsic tube resistance is found to decrease from 10⁵–10⁶ Ω for as-prepared samples to 10⁴ Ω after annealing at 300°C in ambient environment. Measured I–V curves and Schottky barrier heights suggest that the electric contacts are changed from Schottky to Ohmic characteristics after annealing. These results demonstrate that annealing in ambient environment is a simple and efficient way to decrease the contact resistance.

Isotropic conductive adhesives (ICAs) have been developed as an alternative for traditional tin/lead (Sn/Pb) solders for electronics interconnect applications. Low processing temperature, elimination of lead, no-flux, no-clean process and the simple processing are some of the advantages of using ICAs. However, compared to the mature soldering technology, conductive adhesive technology is till in its infancy, and as such, there are some limitations for current commercial ICAs. Besides the conductivity fatigue and poor impact strength, electrically conductive adhesives tend to have lower current carrying capability and higher contact resistance in comparison to the conventional Sn/Pb solder. This is mainly due to the difference in the electrical conductive mechanisms between ICAs and Sn/Pb solders. This study focuses on current capacity measurements and other electrical properties, such as inductance, capacitance and resistance with a LCR meter and a four-point probe both in the direct current (DC) and alternating current (AC) ranges of the ICAs.

Recently, isotropic conductive adhesives (ICAs) have been identified as a potential alternative for lead-containing solders in surface mount technology (SMT) applications. However, current commercial ICAs have some reliability issues that seriously limit their universal acceptance in electronics packaging areas. One of the critical reliability issues is that contact resistance between the ICAs and non-noble metals increases dramatically particularly during elevated temperature and humidity aging. The objective of this study is to investigate the contact resistance behaviors of a class of conductive adhesives, which are based on anhydride-cured epoxy systems, in elevated temperature and humidity environments. Cure profiles, moisture pickup, and shifts of contact resistance of the ICAs on different non-noble metals, such as tin (Sn), tin/lead (Sn/Pb), and copper (Cu), during aging are investigated. It is found that (1) this class of ICAs shows low moisture absorption; (2) the contact resistance of the ICAs on Sn and Sn/Pb decreases first and then increases slowly during 85°C/85% relative humidity (RH) aging; and (3) the contact resistance of the ICAs on Cu remains almost constant after the initial decrease during aging. In addition, the reasons for the contact resistance decrease are studied. Experimental results indicate that the initial contact resistance decrease is probably due to the removal of the insulating organic lubricant layer on silver (Ag) flakes or/and the removal of metal oxide layer on the non-noble metal surfaces by the acid, which is formed after the moisture reacts with the anhydride. From this study, it can be concluded that ICAs based on anhydride cured epoxy systems are promising formulations for surface mount technology applications.