ENVIRONMENTAL FRIENDLY THICK FILM RESISTORS WITH WIDE RESISTANCE RANGE

This paper presents the results on investigation of lead-free and cadmium-free resisti-ve paste compositions based on calcium ruthenate (CaRuO3) and ruthenium dioxide (RuO2), that sheet resistance exceeds 10 kQ/q. Two regulations: Waste Electrical and Electronic Equipment Directive (WEEE), and Restriction of Hazardous Substances (RoHS) were established on July the 1st 2006. They forced the electronics equipment producers to discontinue using lead, cadmium and a few other substances. The Sur-face Mounted Devices (SMD) resistors, that exist in almost every modern electronic device contain thick film resistive layer, according to new regulations cannot contain hazardous substances. The series of new RoHS compliant resistor pastes with resistance range 10 Q/q- 10 kQ/q were elaborated by the authors in 2007. The RuO2 was used as a functional component. However the consumers expect the resistor pastes with the sheet resistance in the range 10 Q/q- 1 MQ/q. Such a resistance range was available using old lead-containing glass and a functional phase containing bismuth ruthenate. However it is considered that such wide resistance range can not be obtained with the use of RuO2 and lead-free glasses. Therefore the authors decided to use calcium ru