Low temperature silver paste applied on multilayer ceramic capacitors

• Main Authors: Hsing-Jung Hsu, 徐杏榕
• Other Authors: Wei-Hua Lu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/82054280539693088497

碩士 === 國立屏東科技大學 === 材料工程所 === 97 === Multilayer ceramic chip capacitors (MLCC) have been widely utilized as miniature-sized, high capacitance, and high reliability electronic components. In accordance with increasing demands for high-performance electronic equipment, multilayer ceramic chip capacitors also have encountered marketplace demand for smaller size, higher capacitance, lower cost, and higher reliability. Based on current trends, it is very clear that multilayer dielectrics for MLCC technology need to address collectively the balance between dielectric permittivity, conductivity, and degradation resistance in their material design. An ever-increasing need for higher capacitance per unit volume multilayer ceramic capacitors (MLCC) has lead to dielectric thicknesses and internal electrode thicknesses in MLCC below 2 μm using traditional thick film MLCC manufacturing technologies. However, there are several problems encountered when decreases dielectric thickness and increases capacitance per unit volume in MLCCs. For example, the microcracks happened after cofiring, it is due to more thermal-shock or high internal stress on MLCCs. In order to avoid thermal-shock of MLCCs, the low temperature firing silver paste is introduced as end-termination. Generally, end-termination paste should be sintered around 700 ℃ in traditional MLCC manufacturing technology. The topic is how to use low temperature silver paste for this technology applied on MLCCs. Therefore, this subject studies the low temperature silver paste applied on traditional MLCCs and compares this technology to potential manufacturing techniques for MLCCs. In this study, several key factors are chosen such as silver powder shape (flake and spherical), epoxy resin types, solvent types, and so on. We also adjust the different ratio of silver powder shape in the paste, for example, 100% flake, 100% spherical and 50% spherical + 50% flake. The pastes are cured at temperature ranging from 180 C to 300 C. The microstructure, mechanical properties and electric properties of samples are analyzed. The silver powder with 50% flake + 50% spherical at curing temperature 300 C exhibited the optimum conditions of paste. In order to improve the adhesion between ceramic chip and low temperature paste, the thin film Ag or Ti is applied as interlayer. The result shows that the adhesion is significant improvement.