Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10409958 | Sensors and Actuators A: Physical | 2005 | 11 Pages |
Abstract
Thick-film PTC resistors (5093, Du Pont, 1 kΩ/sq.) with a high, linear and positive TCR were fired at temperatures between 750 and 950 °C. The development of the resistors' conductive phase and microstructure was investigated by X-ray powder-diffraction analysis and by scanning electron microscopy, respectively. Temperature coefficients of resistivity, sheet resistivities and noise indices were measured as a function of firing temperature. The 5093 resistor material is based on ruthenate, which decomposes during firing at temperatures over 800 °C into RuO2. As the needle-like RuO2 crystals form, the sheet resistivities decrease from very high values to a nominal resistivity of around 1 kΩ/sq. At firing temperatures higher than 850 °C the volume of the single-crystal RuO2 grains increases and therefore their number in a given volume of thick-film PTC layer decreases. The network of “needles ” starts to break, leading to increased sheet resistivities and increased noise indices.
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
Marko Hrovat, Darko BelaviÄ, Andreja BenÄan, Janez Holc, Goran DražiÄ,