Low-Temperature Sinterable Silver Paste for Die-Attachment of Wide Band Gap Power Electronics

The microstructure and morphological properties of the Ag nanoparticles were analyzed by using a field effect-scanning electron microscope (FE-SEM, JSM-7600F, JEOL Ltd., Japan) and Field emission transmission electron microscopy (FE-TEM, JEM-F200, JEOL Ltd., Japan). The struc-ture and phase were identified by a Powder X-ray diffractometer (XRD, SmartLab, Rigaku, Japan) in the range of 0-90° at a scan rate of 10 °/min. The thermal properties and content of the surface stabilizer were measured by thermogravimetric analysis (TGA, Seiko Exstar 6000, SEICO, Japan). The temperature ranged from 25 ℃ to 500 ℃, and the heating rate was 10 ℃/min. The thermal decomposition temperature of the surface stabilizer could be confirmed by differential scanning calorimetry (DSC, Nexta DSC 600, Hitachi, Japan). The temperature ranged from 25 ℃ to 500 ℃, and the heating rate was 10 ℃/min. The viscosity of the paste was measured by a Rheom-eter (ARES-G2, TA, USA) at room temperature for 600 sec at a constant shear rate of 9.99 s-1. In addition, the coating properties of the Ag nanoparticle-based paste were confirmed by using optical measurement (OM, Leica DM 2700M, Leica Microsystems Ltd., Germany) after coating the Ag paste on the substrate using the screen-printing method as described above. The cross-sections of sintered Ag joints were analyzed by scanning electron microscopy (SEM, SU-5000, Hitachi, Ja-pan). Porosity was analyzed by the ImageJ program. Mounting press (ETOS, MTDI Co. Ltd., Ko-rea), polishing machine (FOBOS 100S, MTDI Co. Ltd., Korea), and cross-section polisher (CP-8000, COXEM Co. Ltd., Korea) were used for cross-sectional analysis after sintering.