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Thick film resistors have been prepared by adding glass frits to the conductive materials of the resistors. By this method, it is found that the resistance of the glass phases in the thick film resistors decreases, with a resulting decrease of voltage drift after applying high voltage pulses to the resistors. In addition, the electrical properties and stability of these resistors are improved over resistors made from some present commercially available pastes.

The microstructure and electrical properties of RuO 2 thick film resistors have been studied with special emphasis on the effects of material parameters and processing variables such as size of glass frit particles, RuO 2 -glass mixing ratio, firing conditions, and so forth. A network of RuO 2 develops in a glass matrix on firing, and the increase in the glass particle size enlarged the cell in the network without any significant change in the microstructure. It is shown that a decrease in particle size of glass frit increases the resistance and causes the temperature coefficient of resistor (TCR) to take negative values.

The phenomena of high-frequency-discharge trimming of RuO 2 -basad glaze resistors was investigated as a function of the following: 1) the sintering condition of thick-film resistors, 2) the relation between the amount of additives to resistors and the rate of increase or decrease of resistance, 3) the effect of heat treatment before and after the trimming and effect of glass overcoating, 4) the influence of the trimming on neighboring resistors, and 5) the stability of resistors after the trimming. It has been found that the rate of change of resistance by this trimming is affected by fabrication conditions of the resistor, that its influence on nearby resistance is small, and that the stability of resistors after the trimming is satisfactory.

Accelerated life tests under elevated temperarure, high humidity, and vacuum have been conducted on Pd-Ag thick-film resistors It is found that the change of resistance under those accelerated life test conditions is mainly caused by oxidation and reduction of the electrically conductive components (Pd and Ag) of Pd-Ag thick-film resistors. Through life tests in vacuum, the effect of adsorption was found to be less important than the structural change inside the resistor.

The basic reactions, compositions, and electrical properties of glazed Pd-Ag sintered layers through a firing process have been examined by differential thermal analysis, thermograviometric analysis, and X-ray diffraction analysis. The evaporation and combustion of screening vehicle and solvents, the oxidation-reduction behaviors of Pd and Ag the creation of PdAg solid solution, and the electrical properties and stability of these resistors have been studied. From these tests it was found that the degree of process sensitivity for these resistors was high, and electrical properties and stability of these resistors were affected in much the same way by firing temperature and firing period. They were influenced most by temperature rise rate and least by temperature fall rate.

Mechanism of resistance change by high-frequency-discharge trimming has been investigated for RuO2 glaze resistors. As a result, it is found that the resistance of RuO2 glaze resistors eventually increases when subjected to the discharging over an extended period because of structural damage of the resistor films. As for RuO2 · glass resistors, the resistance increases with the increasing discharge time, but as for Ag- or Nb-doped RuO2 · glass resistors, the resistance decreases during the initial stage of the discharging. The main cause for the resistance reduction is the increasing concentration of Ag atoms in the trimmed area in the case of Ag-dopad resistors, and in the case of Nb-doped resistors the change in valence value of Ru, i.e., Ru4+ -> Ru3+.

The particle sizes of Ru0 2 and glass powder have direct effects upon the resistance value, TCR, and current noise.