Contact resistance

About: Contact resistance is a research topic. Over the lifetime, 15262 publications have been published within this topic receiving 232144 citations. The topic is also known as: electrical contact resistance & ECR.

Electrical conduction models for isotropically conductive adhesive joints

Abstract: An electrical conduction model for silver filled isotropically conductive adhesives (ICA) was developed The model combines the microscopic resistance of the bulk silver particles and the contact between silver flakes with the macroscale resistor network calculation by percolation theory The resistivities of the composites were calculated by resistor network simulations considering both contact effects and particle size effects Three different types of film typically exist on the silver surface: residual organic films; tarnish films; and a thin epoxy layer The contact resistance between silver flakes can be due to a constriction resistance, to the tunneling resistance through insulating films, or to the resistance of more conductive layers The constriction resistance is produced by the restriction of the current flow by small contact spots and is controlled by the actual contact spot area (metallic contact), which is dependent on the contact force between flakes The tunneling resistance is caused by the very thin layer which may reside on the silver flakes between the metallic contact spots, and is dependent on a barrier film thickness and potential Oxide and sulfide tarnish films are typically degenerate semiconductors Two- and three-dimensional (2-D and 3-D) computer simulations were performed to predict the effects of particle sizes, shapes, and distribution on the percolation conduction thresholds and cluster sizes The model predicts that the percolation threshold decreases with broad particle size distributions and high aspect ratio particles The effective resistivity of the adhesive depends on the thickness dimension of the adhesive pad geometry, with very thin layers resulting in high percolation thresholds and high resistivities Resistivity does not change with the pad thicknesses greater than a certain thickness level Silver flake orientation on the surface increases the resistivity of the conductive adhesive pads, but in the same magnitude range The resistivities of the materials are controlled by silver flake sizes and the nature of the contacts

Characterization of heavily doped polysilicon films for CMOS-MEMS thermoelectric power generators

Abstract: This paper presents the material characterization of boron- and phosphorus-doped LPCVD polysilicon films for the application of thermoelectric power generators. Electrical resistivity, Seebeck coefficient and thermal conductivity of polysilicon films doped with doses from 4 × 1015 to 10 × 1015 at cm−2 have been measured at room temperature. Specific contact resistance between polysilicon and aluminum is studied and nickel silicidation is formed to reduce the contact resistance. The overall thermoelectric properties, as characterized by the figure of merit, are reported for polysilicon doped with different doping concentrations. For the most heavily doping dose of 10 × 1015 at cm−2, figure of merit for p- and n-type polysilicon is found as 0.012 and 0.014, respectively. Based on the characterization results, a CMOS compatible thermoelectric power generator composed of boron- and phosphorus-doped polysilicon thermopiles is fabricated. When 5 K temperature difference is maintained across two sides of a device of size of 1 cm2, the output power is 1.3 µW under a matched electrical resistance load.

Schottky diodes from asymmetric metal-nanotube contacts

Abstract: Carbon nanotube Schottky diodes were fabricated using asymmetric metal-nanotube contacts. These devices were prepared from semiconducting single-walled carbon nanotubes contacted by one Al or Ti electrode and one Au electrode. Nanotubes formed a low resistance contact with the Au electrode and a Schottky contact with the Al or Ti electrode. Electronic transport through the Schottky barriers was determined by the competition between tunneling and thermionic emission, which could be tuned by a back gate voltage.

Measuring the Current Distribution in PEFCs with Sub-Millimeter Resolution I. Methodology

Abstract: An experimental technique for measuring the current density distribution with a resolution smaller than the channel/rib scale of the flow field in polymer electrolyte fuel cells (PEFCs) is presented. The electron conductors in a plane perpendicular to the channel direction are considered as two-dimensional resistors. Hence, the current density is obtained from the solution of Laplace's equation with the potentials at current collector and reaction layer as boundary conditions. Using ohmic drop for calculating the local current, detailed knowledge of all resistances involved is of prime importance. In particular, the contact resistance between the gas diffusion layer (GDL) and flow field rib, as well as GDL bulk conductivity, are strongly dependent on clamping pressure. They represent a substantial amount of the total ohmic drop and therefore require careful consideration. The detailed experimental setup as well as the concise procedure for quantitative data evaluation is described. Finally, the method is applied successfully to a cell operated on pure oxygen and air up to high current densities. The results show that electrical and ionic resistances seem to govern the current distribution at low current regimes, whereas mass transport limitations locally hamper the current production at high loads.