Review of Bi2O3-based glasses for electronics and related applications

The present work critically reviews the scientific and patent literature on low-melting bismuth-based oxide glass frits in materials for electronics, sensors and related applications such as sealing glasses, solar cells, architectural and automotive glass, the main motivation being to replace lead-based materials by environmentally more benign ones. Due to similar glass-forming properties of Bi and Pb, Bi-based glasses are the closest "drop-in" alternative for lead-bearing formulations, and are therefore actually replacing them in many applications, helped also by previous experience with Bi-containing materials in thick-film technology and component metallisations. The outstanding issues are discussed, e.g. matching the lowest processing temperatures achieved by the classical lead-based glasses without sacrificing durability and stability, as well as stability vs. chemical reduction. Finally, consideration is also given to special "heavy" glasses (often containing Bi and Pb together) that are useful in fields such as optics, superconductors and nuclear technology, as well as to specific Bi2O3-containing crystalline compounds.