Structure, properties and wetting behaviour on Si substrates of lead-free low melting-temperature Li2O-ZnO-B2O3-WO3 glasses

Abstract

Li2O–ZnO–B2O3-WO3 (LZBW) sealing glasses for Si substrates were prepared and the effect of WO3 on the structure, thermal properties, and sintering behaviour was investigated. As the WO3 increases from 0 to 12 mol%, the glass transition temperature and softening temperature reach the lowest values of 448 °C and 479 °C, respectively, at which time the glass network has the lowest degree of polymerization. The thermal expansion coefficient increases from 6.959 × 10−6/°C to 8.476 × 10−6/°C with increasing WO3 contents. It is verified that the introduction of WO3 can effectively improve the conductivity. The sealing property of the glasses was evaluated by the wetting angle of the glasses after co-sintering with Si substrate for 10 min at 860 °C, and the 25Li2O-7ZnO-2.7Bi2O3-1.3P2O5-55B2O3-9WO3 glass had the minimum wetting angle of 34.07°. The excellent thermal properties, conductivity, and wetting behaviour of the LZBW glasses make it a potential material as a binder material for positive silver pastes.