Study on Glass-metal Bonding by Anodic Bonding.

Anodic bonding of glass and Si, which is performed by applying positive voltage of several hundred volt on Si, is well known as Mallory sealing process and has been in use. However, anodic bonding of glass and metal has not been comprehensively investigated and mechanism of the bonding has not been well understood.A fundamental study on anodic bonding of borosilicate glass and metal was carried out. Glass to Mo bonding and glass to Al bonding were successfully made, and glass to 304ss, glass to Ti, glass to Ni and glass to Au bondings were also made but they fractured at low stress level. Bonding test of glass and Mo using the design of experiment was carried out in order to specify dominant bonding parameters. Then, it has become clear that the bonding temperature and the applying voltage should be dominant in the range of bonding temperature of 400°C-600°C, applying voltage of 0 V-350 V, bonding time of 5 min-60 min, bonding pressure of 0.03 MPa-0.7 MPa in Ar atmosphere or in vacuum. Microscopic observations and chemical analysis were performed for glass to Mo bonded structure. The reaction zone between glass and Mo was not identified from the results of SEM and EPMA. Result of ESCA analysis revealed that Na, which was not found around the boundary, was detected in glass near the anode and Mo oxide was detected in glass near the boundary. Basing on the results, it has been considered that metal ions would diffuse into glass substituting for Na' and metal oxide be formed, then glass to metal bonding should be achieved.