Thick-film and LTCC microvaristors

ZnO-based varistors are frequently used for electronic circuits overvoltage protection. Such material requires sintering at temperatures of 1150degC-1300degC. Lowering it to the typical range 850degC-950degC used in thick-film and LTCC technology is desirable. ZnO-based paste was prepared and exploited for varistors fabrication on alumina and LTCC substrate. Different component topologies, materials for electrodes and firing profiles were used. I-V characteristics of varistors as well as long term stability and durability to high voltage pulses were investigated. Satisfactory results were achieved.