Stable Temperature Dielectrics of (Ba,Ca)(Ti,Zr)O3‐Based MLCCs with Non‐Core‐Shell Structure by Novel Sintering Approach

Abstract

In this study, the high stability temperature coefficient of capacitance (TCC) characteristics of (Ba,Ca)(Ti,Zr)O3‐based multilayer ceramic capacitors (MLCCs) were investigated using a novel sintering approach that combines rapid heating and constrained sintering. The novel sintering approach is based on a sandwich structure that the constrained (Ba,Ca)(Ti,Zr)O3‐based MLCCs are covered with BaTiO3 as a constraining layer on both sides. An in‐plane tensile stress resulting from the mismatch between the constraining layer and the constrained layer during heating can effectively inhibit grain growth of (Ba,Ca)(Ti,Zr)O3‐based MLCCs and then modify the TCC characteristics of (Ba,Ca)(Ti,Zr)O3‐based MLCCs from Y5V (−82%≦△C/C≦ + 22% from −30°C to 85°C) to X5R (−15%≦△C/C≦ + 15% from −55°C to 85°C). The high continuity (>95%) of inner electrode and the fine grain size (0.56 μm) of BCTZ‐based MLCCs with a non‐core‐shell structure can be attained by means of the rapid constrained sintering technique. The lifetime of the fine‐grain‐BCTZ‐based MLCC fired by the novel sintering is superior to that of the coarse‐grain‐BCTZ‐based MLCC fired by conventional sintering in a highly accelerated life test.