Electric Field-assisted Anodic Bonding of Glass to Kovar Alloy

Electric field-assisted anodic bonding of glass to Kovar alloy was preformed at temperature 613 K under applied voltage 500 V.The interfaces were investigated by SEM observation and EPMA analyses.In order to determine the joint strength,shear tests were carried out.The results show that intimately contacted area between Kovar alloy and the glass enlarges from initial contact area with increase of bonding time.Na and K ions involved in the glass move toward the cathode from the anode surface under the electric field,resulting in depleted layers of the adjacent anode surface.The thickness of depleted layers increases with increasing bonding time.The stable joint strength of about 8~12 MPa can be achieved as long as ≈100% intimately contacted area between Kovar alloy and the glass is obtained.These results are discussed by considering the inference of the applied electric field.