Direct glass-to-metal joining by simultaneous anodic bonding and soldering with activated liquid tin solder

Anodically bonded glass/titanium and glass/steel were investigated for applications in a variety of industrial sectors. Residual stresses that build up during the bonding or cooling down of a joint to room temperature represent the main challenge to the joining process since they drastically weaken the mechanical strength of the joint. A layer of liquid tin-based solder in between the glass and metal part of the joint is used to reduce the internal stresses and improve the contact between the surfaces. The microstructural characterization of glass/solder/titanium and glass/solder/steel joints formed from Ni coated metal substrates indicated that Ni3Sn4 was formed for both types of joint but with a different morphology and location depending on the type of metal substrate. The average shear strength of the joints was 24 MPa for glass-titanium and 21 MPa for glass-steel joints. For both types of joint, the fracture crack propagated along the glass-solder interface.