Polymer Based Thick Films - Material Quality and Interface Resistance Evaluation

conference paper

English

We have studied the properties of polymer based thick film layers. The samples were made using different resistive pastes and dipping silvers. The composite of carbon and graphite (C/Gr) conducting particles suspended in different polymer vehicles were used for the thick film resistive layers preparation. Interface resistance Rc created between dipping silver (DiAg) contact layer and resistive layer was determined from the surface potential distribution measurements and its value was less than 1% of total sample resistance. The temperature dependence of conductivity was measured in the temperature range 110 to 310 K. VA characteristic is linear in both electric field orientations. At the temperature 308 K the VA characteristic is very near to that on 110 K, but the resistivity temperature coefficient has opposite sign. Minimum resistance value is at temperature 230 K. For increasing temperature the sample resistance increases with temperature: R is proportional to Ta, where a = 0.5 to 1.5. For the decreasing temperature sample resistance increases as well. We have found that for low temperature range conductivity is thermally activated with activation energy about Ea = 15 meV. We have applied new principle for non-destructive testing of conducting solids which is based on the phonon interaction with conducting electrons. The ultrasonic signal change the contact area between conducting grains and then resistance is modulated by frequency of ultrasonic excitation. Resultant intermodulation voltage depends on the value of ac current varying with frequency fE and on the ultrasonic excited resistance change dR varying with frequency fU. The intermodulation component of frequency fm = fE-fU varies linearly with electric excitation and quadratic dependence on ultrasonic excitation was observed. The main task was to determine the influence of polymer thermal expansion and its wetability on the thick film conductivity. The point contacts between conducting grains are of two types: (i) for polymers with good wetability the thin polymer layer is formed between conducting grains, the structure has semiconductor like conductivity, the resistance decreases with increasing temperature. (ii) For polymers with low wetability the direct contact between conducting grains exists, the structure has metallic like conductivity.

Polymer Based Thick Film, Interface Resistance,

SEDLÁKOVÁ, V.; ŠIKULA, J.; SPIRALSKI, L.

2006

1. 1. 2006

Institute of Electron Technology - Cracow Division

Krakow, Poland

83-917701-3-3

XXX International Conference of IMAPS Poland Chapter Proceedings

95

102

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