Resistance Of Thick-film Resistors Research Articles

Thermodynamic assessment of phase relations in the system PbO–RuO2–TiO2

Lead ruthenate $(Pb_2Ru_2O_{6.5})$ with pyrochlore structure is one of the phases that form in thick-film resistors, which consist of a conducting oxide dispersed in a lead borosilicate glass with minor additions. Lead ruthenate converts to $RuO_2$ when the PbO concentration in the glass is reduced. $TiO_2$ is added as a modifier to lower the temperature coefficient of resistance of thick-film resistors.

Conductive powder preparation and electrical properties of RuO2 thick film resistors

RuO2 powders were prepared under different conditions to vary their properties. A study was made of the powder properties and electrical characteristics of thick film resistors (TFRs) containing an RuO2 powder as a conducting component. Both crystalline size and specific surface area varied with calcination temperature but the change in the washing solution had different effects upon the two relationships. Variations in the total pore volume produce differences in the specific surface area at the same crystalline size. The resistivity of TFRs decreases and the temperature coefficient of resistance (TCR) becomes more positive with decreasing crystalline size. TFRs having conductive powder of higher specific surface area at the same crystalline size show lower resistivity and higher TCR values.

The effect of applied frequencies and multiple firing on the resistance of thick film resistors : Bi-Shiou Chiou, Wei-Yung Hsu and Jenq-Gong Duh. IEEE Transactions on Components, Hybrids, and Manufacturing Technology15(3), 393 (1992)

The effect of applied frequencies and multiple firing on the resistance of thick film resistors : Bi-Shiou Chiou, Wei-Yung Hsu and Jenq-Gong Duh. IEEE Transactions on Components, Hybrids, and Manufacturing Technology15(3), 393 (1992)

Resistance adjustment with short-pulse Nd:YAG laser for RuO/sub 2/-based thick-film resistors buries in polyimide film

To adjust the resistance of thick-film resistors (TFRs) buried in polyimide film, a process using a laser is proposed. Short-duration pulses from an Nd:YAG laser are used to irradiate the TFRs through the polyimide film. The TFR surface is modified thermochemically, and the resistance is reduced by an increasing amount with an increasing number of laser pulses. Because a 5-ns laser pulse is too short to start vaporization, no degradation of the polyimide film occurs. Temperature dependences of resistance show that the electrical conduction in the laser-modified TFR differs from that in the original TFR, because of higher electron density. >

The effect of applied frequencies and multiple firing on the resistance of thick film resistors

The resistance and impedance as functions of frequency for Dupont 1600-series thick-film resistors are investigated. It is reported that there exists an abrupt decrease in the resistance around 1 MHz. An equivalent circuit model is proposed to explain the high-frequency behavior in the resistor. After multiple times of firing, the resistance is altered and the relative change is related to the intrinsic resistance in the resistor. It is argued that the resistance variation is associated with the microstructure evolution of the resistor, in which the rearrangement of conducting grains in the glass matrix plays a major role. >

Mathematical relation between RuO2 volume fraction and resistance of thick-film resistors

The mathematical relation between volume fraction RuO2 and the resistance of RuO2-glazed thick-film resistors has been deduced in terms of the diameters of the RuO2 particles and glass frits and some physical properties of the glass. The equation obtained can qualitatively describe the relation between RuO2 volume fraction and the resistance values. Therefore, valuable information can be obtained for the design of thick-film resistors.

An advanced laser application for controlling of electric resistivity of thick film resistors

When electric resistivity of Thick Film Resistor (TFR) is adjusted to the desired value, laser beam is irradiated onto the resistor material so that a part of the resistor material is instantaneously vaporized and cut away. This conventional laser trimming method to adjust the resistivity of TFRs is an indispensable technique for manufacturing elec-tronic devices such as hybrid ICs. A peculiar phenomena was revealed by us, that is, when specially selected pulse laser beams were irradiated to TFR, the TFR was surface modified without cutting grooves, and then resistivity of the TFR was decreased. We completed the advanced laser process to apply this peculiar phenomena. 8 By comparing with conventional trimming processes, we can show prominent features of the advanced process, for example, resistivity of fine size TFR (300 micrometers-width and under) can be easily controlled. The decrease in resistivity of the TFR is considered to result from the decrease in specific resistivity of glass in the TFR. Because it is considered that the glass in the TFR is heavily doped with ruthenium impurities during the surface modification due to results of morphology observations and x-ray diffraction analysis. We have applied this advanced laser process to fine size TFR (300 micrometers-width), and developed high density hybrid ICs.

Thick Film Resistors Not Only on Ceramics: How to Obtain Suitable Layout Parameters

The square resistance of thick film resistors on dielectric layers can show a very complex behaviour. From resistance measurements of a test pattern three suitable paste parameters Q(L), M(L) and A(L) can be calculated as numerical functions of the resistor length L. All formulae needed for establishing an accurate resistor layout by means of the parameters are presented in this paper. The three‐dimensional surface of the square resistance as a function of length L and width W can also easily be calculated.

Influence of the degree of dispersion of ruthenium dioxide on the electrical properties of thick-film ruthenium resistors

The particle size of the functional material of resistive pastes has a significant influence on the specific resistance and temperature coefficient of resistance of thick-film resistors. The authors of this article investigated the influence of the degree of dispersion of ruthenium dioxide on the specific resistance and temperature coefficient of resistance of ruthenium thick-film resistors in a broad range of change in content of the conducting phase.

Tunnelling in thick-film (cermet) resistors and the minimum of resistance

The electrical transport in thick-film resistors (TFRs) is actually an active field of investigation on both theoretical and experimental bases. Previously it has been shown that tunnelling of electrons between neighbouring grains could explain a large spectrum of experimental findings and it has been proposed that the minimum of resistance of TFRs is due to a trade-off between the negative temperature coefficient of the resistance of the tunnelling barrier and the positive temperature coefficient of the metal-oxide grains. In this paper the approach is re-examined and it is shown that a more satisfactory interpretation of the minimum of resistance is obtained by neglecting the resistance of the grains and assuming a slight increase of the tunnelling barrier height at increasing tem-peratures. Under this assumption a very good agreement between experimental and theoretical values is found for the temperature coefficient of resistance of TFRs over a temperature range from 77 to 600 K. The possible origins of the temperature dependence of the barrier height are discussed and the practical consequence of the proposed model emphasized.

Strain Sensitivity in Thick-Film Resistors

Piezoresistive properties of Dupont 1400 series thick-film resistors have been investigated by measuring longitudinal and transverse gauge factors as a function of applied strain between 0 and _+ 1000 microstrain in the temperature range from -70 to + 140°C. The relative change in resistance of thick-film resistors is linear, reproducible, and hysteresis free for the full range of applied strain. They appear more sensitive than metal resistors and have a low temperature coefficient of resistance (TCR) and gauge factor.

The effect of particle size on the temperature coefficient of resistance of thick film resistors

The effect of the particle size on the temperature coefficient of resistance (TCR) of thick film resistors, based on RuO 2 or Pb 2Ru 2O 7 as the resistive material, was investigated. It was found that the particle size and the surface roughness have a significant influence on the TCR value of the resistors. The shape of the TCR versus resistance curve is ascribed to the particle size distribution in the resistive material. When monodisperse particles are used, cermets with a small and constant TCR value in the high ohmic region (1 kω−10 Mω) can be prepared.