Fluctuation Of Contact Resistance Research Articles

Mathematical Model of Contact Resistance in Pantograph-Catenary System Considering Rough Surface Characteristics

Pantograph-catenary system is a key component of high-speed railway. Under high speed and strong current operation conditions, the surface roughness of the sliding electrical contact between contact wire and slide changes continuously. It will cause the fluctuation of contact resistance and lower the electrical contact property of the system. Therefore, it is of great significance to study the relationships between the contact resistance and surface roughness characteristics. In this article, lots of current-carrying friction experiments were carried out under different contact pressure, contact current, and sliding speed conditions. A roughness tester was used to measure the roughness of the contact surface after the experiment. Four characteristic parameters were proposed to describe the roughness. They are the root mean square and the maximum peak height of the rough surface, the peak count, and the curvature radius of asperity, respectively. The function relationships between these characteristic parameters and experimental conditions were obtained and discussed. On the basis of Greenwood–Williamson contact model, a new mathematical model of contact resistance in the pantograph-catenary system considering rough surface characteristics was established and verified. It can be used to further study the current conduction mechanism of sliding electrical contact in pantograph-catenary system and evaluate the electrical contact performance.

Degradation Phenomenon of Electrical Contacts by Oscillating Mechanisms - Modeling about Fluctuation of Contact Resistance -

Degradation Phenomenon of Electrical Contacts by Oscillating Mechanisms - Modeling about Fluctuation of Contact Resistance -

Degradation Phenomenon of Electrical Contacts by using a Micro-Sliding Mechanism -Modeling about Fluctuation of Contact Resistance-

Degradation Phenomenon of Electrical Contacts by using a Micro-Sliding Mechanism -Modeling about Fluctuation of Contact Resistance-

Random Telegraph Noise in 1X-nm CMOS Silicide Contacts and a Method to Extract Trap Density

The behavior of random telegraph noise was affected by nickel silicide barrier height engineering in advanced nano-CMOS technologies. Contact resistance fluctuations with magnitude of up to 40% were observed when a Schottky barrier was reduced to 0.2 eV. The large contact resistance instability is attributed to the barrier modification by positive charge trapping and detrapping in a Schottky contact. The prevalence and magnitude of the noise are dependent on the contact area, trap density, trap energy, and the silicide Schottky barrier height. In this letter, we propose a fast method to extract the density of responsible contact traps.

Impact of Random Dopant Fluctuation on Size-Dependence of Contact Resistance

Reducing the size of semiconductor devices causes contact in deca-nano size. Substantial fluctuation of contact resistance is anticipated owing to the reduction of impurity atoms in the contact holes. In this study, the impact of the random dopant fluctuation on the contact resistance is revealed by three-dimensional device simulation with a Schottky contact model. The standard deviation of the contact resistance could become 50%, dominated by the number of impurity atoms in the depletion layer formed by the Schottky barrier. The average value of the contact resistance could increase as the impurity concentration decreases because of the reduction of the tunneling path.

Long-term, Redox and Thermal Cycling Stability of Electrolyte Supported Cells

The electrolyte supported cells with low area specific resistance (ASR<0.34 Ohm cm²) have been tested for long-term, thermal and redox stability in ceramic housing. It has been shown that the cells with optimized anode microstructure have degradation <0,1 % / 1000h and no measurable resistance change in the range of mistake of used method after ten thermal and redox cycles. The small fluctuation of contact resistance between anode and current collector has been observed especially during cycling experiments. The redox cycles lead to the largest fluctuation of ASR values during cycling due to direct influence on the bonds between anode and current collector.

Studies on temperature coefficient of resistance (TCR) of polymer thick film resistors

PurposeThe purpose of this paper is to study the variation of the temperature coefficient of resistance (TCR) of polymer thick film resistors, namely, PVC‐graphite thick film resistors, with parameters such as volume fraction, grain size, and high voltage.Design/methodology/approachA model is proposed to explain the observed variations, which assumes that the texture of the thick film resistors consists of insulator granules coated with conducting particles.FindingsThe paper finds that the TCR of these materials is controlled mainly by the contact resistance fluctuations between the conducting particles and the number of contacts each particle has with it neighbours. The variation of TCR with high voltage has also been explained with the help of this model and it is attributed to the changes in contact area and the number of contacts.Originality/valueThe value of the paper is in showing that apparently the TCR of polymer thick film resistors can be controlled by the expansion properties of the insulating medium. The variation of TCR with high voltage is also due to change in number of contacts between the conducting particles. These types of material may find applications in thermal sensors or as temperature control elements.

The effect of thermal cycling on the contact resistance of anisotropic conductive joints

Purpose – Anisotropic conductive film (ACF) offers miniaturization of package size, reduction in interconnection distance and high performance, cost‐competitive packaging and improved environmental impact. However, a major limitation for ACF is the instability caused by thermal warpage. The purpose of this paper is to study the effects of thermal warpage on contact resistance in real time i.e. make online measurements of contact resistance fluctuations while the assembly undergoes thermal shock.Design/methodology/approach – The ACF assemblies are subjected to thermal cycling with different temperature profiles that have peak temperatures either below or above the glass transition temperature (Tg) of the ACF. The flex substrate used was made of polyimide film, with Au/Ni/Cu electrodes and a daisy‐chained circuit matched to the die bump pattern. The ACF used was based on epoxy resin in which nickel and gold‐coated polymer particles are dispersed. A comparative study was carried out on the results obtained.F...

Variation of contact characteristics for metal to p+ junctions using TiN as diffusion barrier

The contact characteristics of metal to p + junction using TiN as diffusion barrier were studied. Erratically high contact resistance is found when the TiN is formed by rapid thermal nitridizing the sputtered Ti, especially for contact holes with smaller feature size. The large fluctuation of contact resistance is primarily caused by the poor interfaces. To achieve good contact integrity, sufficient silicidation by a proper process scheme is indispensable to clear the interface (or completely annihilate thin native oxide). In the deep submicron intergation technology, the formation scheme of the contact barrier should be taken into account significantly.

Degradation of Al-Al and Al-Cu connections due to fretting

The degradation of Al-Al and Al-Cu electrical connections under fretting conditions has been studied. In addition to contact resistance measurements, scanning electron microscopy (SEM) and X-ray fluorescence analysis were used to study the processes involved. The fretting tests were carried out with a simulated connector configuration at an oscillation frequency of 0.0033 Hz, slip amplitudes of 10 and 25 μm and contact loads of 2 and 10 N on lubricated and non-lubricated connections. The results showed that fretting adversely affects the contact resistance of Al-Al and Al-Cu connections, which show a rapid increase and substantial fluctuations with fretting time. The effects of fretting were reduced to some extent by applying higher contact loads, whereas lubrication practically eliminated the sharp fluctuations in contact resistance. SEM and X-ray fluorescence analysis revealed that considerable damage of the contact zones occurred as a result of the fretting action and substantial transfer of material was observed in Al-Cu connections.

Effects of adhesive junctions and metal transfer on the mechanism of fluctuations in contact resistance

Fluctuation in contact resistance during sliding contact, an important indication of the contact interface condition, has been analyzed from the viewpoint of adhesive wear. An equation which is able to estimate the fluctuations in contact resistance was deduced, as the adhesive junction is considered to be the main electric current path. It was shown that fluctuations in contact resistance caused by adhesive wear can be estimated in terms of ( W/ P) − n and the properties of the contaminant films. Moreover, in metal transfer, which is important in dissimilar metal combinations, it was found that the nature of the transfer is determined by W ab / P and hardness. In the combination of metals with a high value of W ab / P and a large difference in hardness, a smooth stable sliding condition was obtained by transfer of the soft metal.

Noise spectrum for fluctuations of contact resistance and mechanism of noise generation in sliding contact

Noise voltage due to fluctuations in contact resistance arising from sliding contact varies with the kind of contact metals. The frequency spectrum of the noise power density resulting from sliding motion is assumed to be influenced by the properties of the metal surface. Moreover, the causes of the noise generation due to fluctuations in contact resistance are considered to be fairly well understood by investigating the frequency spectrum of the noise. By analyzing the frequency spectrum of the noise it was found that there are three types of noise spectra depending on the properties of the metal surface. Noise spectra with an f − 1 2 characteristic are found in metals with large values of W P , those with an f −1 characteristic in noble or like metals, and those with an f −2 characteristic in hard base metals.