A crack propagation analysis of multilayer ceramic capacitors

In the paper we consider a multi-layer ceramic capacitor (MLCC) of size 1206 with X7R dielectric. The main goal of this study is to analyze the behavior of micro cracks in the ceramic such as to determine if they are able to propagate and if so to determine the preferred direction of propagation. A four-point bending setup of soldered MLCC has been used and a finite element model of the soldered capacitor has been developed using ANSYS v. 13. The printed circuit board (PCB), solder and chip ceramic capacitor are considered in this model. Firstly, thermal cool down after soldering has been simulated for analyzing the loads induced in the capacitor to solder pad interface due to the difference of the thermal expansion coefficients. The resulting tensile stresses in the dielectric can cause flaws which can lead to failure. Afterwards a four point bending simulation has been done and fracture parameters have been extracted based on the theory of linear elastic fracture mechanics.