Abstract
The purpose of this paper is to study high voltage interactions in polymer thick film resistors, namely, polyvinyl chloride- (PVC-) graphite thick film resistors, and their applications in universal trimming of these resistors. High voltages in the form of impulses for various pulse durations and with different amplitudes have been applied to polymer thick film resistors and we observed the variation of resistance of these resistors with high voltages. It has been found that the resistance of polymer thick film resistors decreases in the case of higher resistivity materials and the resistance of polymer thick film resistor increases in the case of lower resistivity materials when high voltage impulses are applied to them. It has been also found that multiple high voltage pulse (MHVP) stressing can be used to trim the polymer thick film resistors either upwards or downwards.
Highlights
The resistance adjustment of cured resistors forms an integral part of polymer thick film technology
In the case of frit glass based thick film resistors, it is well known that the application of high voltage pulses leads to some sort of micro welding between the conducting granules, which in turn leads to a decrease in resistance of high value resistors [9]
In the case of frit glass based thick film resistors, the application of high voltage pulses leads to increase in conductivity of low conductivity thick film resistors and leads to decrease in conductivity of high conductivity thick film resistors with local heating
Summary
The resistance adjustment of cured resistors forms an integral part of polymer thick film technology. The resistance adjustment is done either by removing a portion of the resistor material by a narrow jet of abrasive particles (Air abrasive trimming) or by the evaporation of the part of the material from the substrate by a high power laser beam (Laser trimming) [1–8]. The above trimming methods are used to trim the resistors upwards only. Downward trimming is not generally attempted because it calls for the addition of the materials to the film. There seems to be another method of changing the resistance by changing film conductivity to higher or lower values with high voltage pulses. High voltage pulses are applied to polymer thick film resistors to trim downwards by changing their conductivities [9–22]
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