High-voltage pulse stressing of thick-film resistors and noise

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Abstract

In this paper the results from a study of high-voltage pulse stressing effects on resistance and low-frequency noise of thick-film resistors based on two different resistor compositions with sheet resistances of 10 and 100 kΩ/sq are presented. For the experimental purposes thick-film test resistors of different dimensions were realized and exhibited to voltage pulses with 1500 and 3000 V amplitudes. Obtained experimental results are qualitatively analyzed from the microstructure, charge transport mechanism and low-frequency noise aspects. Correlation between resistance and low-frequency noise changes with resistor degradation due to high-voltage pulse stressing is observed. It is shown that low-frequency noise is more sensitive to this kind of resistor stressing than resistance and that measured values of noise index are in agreement with resistance noise spectrum results.

Introduction

Several papers were published dealing with different problems of understanding the nature of noise in thick-film resistors [1], [2], [3] but the possibilities that noise measurements can be used for thick-film resistor quality evaluation and evaluation of degradation under stress are insufficiently investigated. A reason for that may be complexity of thick-film resistor microstructure and conduction mechanisms as well as poor understanding of their relationship with noise. On the other hand, different conditions of thick-film resistor application are inducing the need to investigate their behavior under stress, especially high-voltage pulse stress. Several papers dealt with high-voltage pulse trimming of thick-film resistors [4] and behavioral analysis of thick-film surge resistors that are being used in telecom systems as protection under extreme working conditions such as lighting strikes or power cross conditions on external lines [5], [6], although the problem is physically different for surge resistors because of their low ohmic resistances. However, bearing in mind the present miniaturization trend and mass usage in up-to-date very sensitive communication systems, little attention has been paid to the influence of high-voltage pulse stressing on structure and noise performances of conventional thick-film resistors [7], [8]. In this paper the results from a study of high-voltage pulse stressing effects on thick-film resistors are given using resistance measurements as well as measurements of low-frequency noise parameters––resistance noise spectrum and noise index. Experiment––materials, test samples and terms of high-voltage pulse stressing and measurements are described in Section 2, and experimental results and discussion are given in Section 3. Special attention is paid to investigation of correlation between high-voltage damages and low-frequency noise and to possibility of using low-frequency noise for diagnostics of microstructure defects in resistors caused by high-voltage pulse stressing.

Section snippets

Materials and test resistors

Behavioral analysis of thick-film resistors subjected to high-voltage pulse stressing was performed using two groups of thick-film test samples with different resistor geometries (Fig. 1). First group of test samples (Fig. 1a) contains 18 resistors of width w=1 mm and different lengths, while second group of test samples (Fig. 1b) contains 15 resistors with different geometries, both lengths and widths. Test samples were formed on ceramic alumina (96% Al2O3) substrates using conventional

Experimental results and discussion

In order to illustrate performed experiment, typical results obtained by resistance, voltage noise spectrum and noise index measurements for thick-film resistors that were subjected to high-voltage pulse stressing and which degraded but did not fail catastrophically are given in Fig. 3 and Table 1. The results are given for resistors with identical geometries (1 × 2 mm2) and the initial resistance of 16 kΩ from the test-sample group A that were subjected to the impact of 11 pulses with 1500 V

Conclusion

In this paper the results obtained from resistance, noise voltage spectrum and noise index measurements performed on two groups of test resistors based on two commercially available thick-film resistor compositions with different sheet resistances and subjected to high-voltage pulse stressing, are given. Correlation between resistance and low-frequency noise changes and high-voltage pulse stressing is observed. It is shown that low-frequency noise, expressed through noise index or resistance

Acknowledgements

This research was partially supported by the Serbian Ministry of Science and Technology (contract IT.1.04.0062.B).

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