Low-temperature sinterable silver paste for die-attachment of wide band gap power electronics

Abstract

Herein, we introduce a simple fabrication method of the Ag paste for low-temperature sintering for die-attachment of WBG power electronics. Silver nanoparticles (Ag NPs) were chosen for the die-attachment materials for their superior electrical and thermal conductivity and capability of low-temperature sintering driven by nano-sized structures. Ag paste was fabricated by simply mixing Ag NPs with general organic solvents without any organic additives. The optimal composition of the Ag paste was selected with 2-butoxyethanol as a solvent and the Ag content with 70 wt. %. The optimized Ag paste showed good processability to the screen-printing method with a low-roughness surface without visible cracks. We obtained a superior shear strength of 55.5 MPa with fast sintering for 150 s at 180 °C. Despite the low sintering temperature and short holding time, Ag NPs could be rapidly melted and densified due to their large surface areas and low-temperature decomposable organic ligands around the Ag NPs. Dense Ag joint also exhibited low porosity under 6 % leads to robust structures. Based on these results, we confirm that our low-temperature sinterable Ag paste has the potential as a promising material for die-attachment of WBG power electronics.