Advanced Ceramic Capacitor Solutions for High Temperature Applications

Abstract

For high temperature applications at 150°C or above, such as those in electronics for down-hole drilling, geothermal energy generation and power electronics, a robust dielectric material is necessary for capacitors. Ceramic capacitors using X7R and X8R type dielectrics are designed for applications up to 125°C and 150°C, respectively. At temperatures above 150°C, these X7R/X8R types of ceramic capacitors typically suffer from degradation of reliability performance and severe reduction in capacitance, especially when bias is applied. Recently, a Class-I dielectric material has been developed using Nickel electrodes for high temperature application up to 200–250°C. Due to its linear dielectric nature, this material exhibits highly stable capacitance as a function of temperature and voltage. This paper will report electrical properties and reliability test data on these Class-I type ceramic capacitors in SMD chip and leaded configurations at 150–200°C and above, and discuss possible mechanisms behind the robust reliability of this high temperature dielectric.