A Comparison of Multilayer Ceramic Capacitor Technologies for High Temperature Applications

Abstract

Multilayer ceramic capacitors remain an important component in high temperature circuitry due to the general robustness of ceramics at application temperatures greater than 200°C. However, standard MLCC dielectric compositions either exhibit very low dielectric constants at high temperatures or show excessive capacitance loss with increasing temperature in this regime. Many also see a significant degradation in insulation resistance, leading to very low RC products for the materials. Stability of properties with dielectric field is also a critical factor in many applications, both for improved energy storage and capacitance per unit volume. In recent years, a new class of weakly-coupled relaxor ceramic compositions has emerged which offer significant benefits in dielectric constant and capacitance stability at high temperatures. Tailoring of these compositions can offer increased capacitance stability over wide temperature regimes, or maximized capacitance in the high temperature (>200°C) realm. In this discussion, a comparison is made between MLCCs constructed of a standard commercial dielectric material and one of these new compositions. Emphasis on performance at high temperature and the outlook for expansion of this class is given.