Rate controlling processes in anodic bonding of boroslicate glass-to-Kovar alloy coated with Al film

摘要

The Kovar alloy disks coated with Al film were anode-bonded to the glass at temperatures of 513～713 K under the static voltage of 500 V. The kinetics of enlargement of intimate contact area between the Kovar alloy and the glass was examined, and the joint strength was determined by the shear tests. It is suggested that a critical temperature of about 663 K exists. The enlargement of intimate contact area is achieved mainly by elastic deformation of the glass at temperature lower than the critical temperature. The estimated activation energy is close to that of conductivity of the glass.Whereas, the enlargement of intimate contact area is achieved mainly by viscous flow of the glass, and the corresponding activation energy is higher than the former and is a combination of the activation energies of conductivity and viscous flow of the glass. Examination of joint strength reveals that the chemical bond or complete bonding is formed as soon as the surfaces are brought into intimate contact, and rate-controlling process in anodic bonding is considered to be the rate of enlargement of intimate contact area.