Lead-free low-melting point sealing glass in SnO–CaO–P2O5 system

Development of lead-free low-melting point sealing glass with properties such as low coefficient of thermal expansion (CTE), low glass transition temperature (Tg), low softening temperature (Tf), low cost, high electrical resistance and high chemical stability, has been under strong market demands. Research on the development of lead-free low-melting point sealing glass in SnO–CaO–P2O5 (SCP) system was carried out. A large glass formation composition region in the SCP ternary system was found. The SCP glass, possessing properties of low Tg (< 690 K) and high thermal stability, is suitable for low-to-mid temperature sealing applications in the industry. Its CTE is in the range 90–100 × 10− 7 K− 1, suitable for most device substrates. SiO2 doping with different amounts decreases the CTE and increases the electrical resistance linearly, and improves the water durability by exponentially decreasing the relative mass loss. However, the CTE and the electrical resistance of the glass doping with B2O3 both show a maximum at about 2 mol% B2O3 doping.