| Popis: |
The percentage variation of resistance of PVC-graphite thick film resistors has been studied. Two different grain sizes of graphite, as well as four different compositions of PVC- graphite are adopted in the preparation of thick film resistors. Among the four different compositions of PVC-graphite i.e. 90%:10% to 60%:40%, 90%:10% PVC-graphite composite thick film resistor shows the least variation with temperature changes. This can be attributed to high composition of graphite. The variation will be lowered down with a decrease in the loading fraction of PVC in thick film resistors. The percentage variations of resistance of PVC-graphite thick film resistors, after 700C for 1000 hours, or after 30 cycles thermal shock tests as well as the variations after the short term overload tests, have been measured and studied. A possible explanation on these experiments is also presented. |
