Optimized solder alloy for glass-to-metal joints by simultaneous soldering and anodic bonding

Strong glass/solder/metal seals were prepared between float glass, tin solder and Fe-Ni alloys by the Activated Liquid Tin Solder Anodic Bonding (ALTSAB) process that combines classical anodic bonding with a liquid solder to ensure a near perfect contact between the bonding surfaces. The optimization of the Al content of the solder enables the production of glass/solder/metal joints without pre-treatment of the metal or glass surfaces. Strong glass/solder bonds are formed by anodic bonding across the oxide/metal interface and strong solder/metal bonds are formed simultaneously by soft soldering. The combined process consists of two very different processes and the optimal solder composition represents the middle ground between the requirements for both interfaces. The glass/solder bond strength increases with increasing Al content at the expense of the solder/metal bond strength: solders with a very low Al content of 75 ppm constitute the best compromise and result in the strongest glass/solder/metal joints. The optimal solder composition was used to anodically bond Dilaton Fe-48 wt%Ni frames to the edge of 500 × 500 mm2 float glass panes for vacuum glazing applications.