Chemical reaction between Fe-Si-Cr alloy powder and inner electrode Ag during co-firing for multilayer alloy power inductors

• Main Authors: Hsin-YunChiang, 蔣欣芸
• Other Authors: Hsing-I Hsiang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/xp9h33

碩士 === 國立成功大學 === 資源工程學系 === 106 === In this study, multipurpose X-Ray thin-film diffractometer, transmission electron microscope (TEM), and scanning electron microscope (SEM) were used to investigate the chemical reaction between Fe-Si-Cr alloy powder and internal electrode, silver, during co-firing for multilayer alloy power inductors. The experimental results show that oxygen not only promotes the volatilization and diffusion of Ag but also causes the printed circuit to become discontinuous or even disconnected, and it will also react with Ag and the volatile Cr2O3 to form a large amount of flaky AgCrO2 (silver chromite). Since AgCrO2 is a p-type semiconductor, the formation of this crystalline phase will consume Ag and Cr2O3, which will eventually lead to the problems of insufficient insulation resistance and the decrease of breakdown voltage. On the other hand, this study also designed experiments to investigate the formation mechanism of flaky AgCrO2. The experimental results show that silver reacts with the Fe-Si-Cr thermal grown oxide layer, Cr2O3, to form Ag2CrO4 at temperatures under 650 ˚C. The formed Ag2CrO4 with low melting temperature then volatilizes at higher temperatures through the pore channels to react with the volatilized Cr2O3 to form the AgCrO2 via gas phase reaction. Then AgCrO2 will decompose to Ag and Cr2O3 at the temperature higher than 800°C.