Characterization of a Bonding Method for High Borosilicate Glass to Kovar Alloy Sealing by Laser Welding

Glass to metal sealings have many excellent properties and they are extensively used in various industries. Applications for laser glass tube for carbon dioxide laser requires hermetic and mechanically strong seals. With the purpose of fully utilize its effectiveness of glass and metal sealings’ properties and enlarge their applications, bond the glass to metal is an important method. Hermetic seals between kovar alloy and borosilicate glass can be produced using a novel laser sealing method when compared to bonding method based on glass pressing at temperatures around the softening point. This paper presents investigation results for the shear tensile bond strength and the waterproof resistance depending on the manufacturing process parameters. The shear bond strength of the glass to metal sealing was amounted to only 9.84 MPa when using traditional high temperature holding process. The maximum shear bond strength can be amounted to 43.68 MPa when sealed by laser welding process. And good adherence with a very high waterproof resistance can ben obtained. The bonding mechanisms was revealed by SEM methods to analyze the interface.