Measurement and Analysis of the Enhancement of Mechanical Properties and Reliability of Multilayer Ceramic Capacitors

• Main Authors: Kun-Yen Chen, 陳昆彥
• Other Authors: Chun-Hway Hsueh
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/87339438517007885615

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 101 === The multilayer ceramic capacitor (MLCC) is becoming one of the indispensable electronic components. Therefore, its mechanical strength, lifetime and reliability are of great concern. The characterization of the mechanical properties of MLCCs, direct loading by conventional facilities is not suitable because of its small size. To date, the standard method used to determine MLCC’s mechanical properties is board flex test; i.e., mounting the capacitor onto a printed circuit board (PCB) and applying bending to the entire system. Failure is defined as cracking or capacitance loss of the MLCC when the mounted PCB is subjected to a specified deflection, and the measurements are usually performed after the test. In this thesis, acoustic emission was used to detect cracking of MLCCs during the board flex test. To confirm cracking-induced acoustic emission, telemicroscope was used to perform the in-situ observation of cracking. Finite element analyses were also performed to analyze the stress field resulting from the test to compare with the observed cracking path. In addition, nanoindentation was used to explore the mechanical properties of the constituents of MLCCs in the nanoscale. Meanwhile, an alternative soldering method was used to mount the MLCC onto the PCB and fracture pattern was observed and compared to that from the normal soldered MLCC. The shift of the location of crack and stress concentration provides design guidelines on improving the MLCC’s lifetime and mechanical strength. Our work not only allows identification and understanding of the fracture origin, but also provides guidelines in the material design.