Gold-to-alumina solid state reaction bonding

This paper describes methods by which strong vacuum-tight bonds between gold and alumina can be fabricated in an air atmosphere. Temperature was found to be a sensitive factor in bond formation; the higher the temperature, the stronger the bond, provided that the temperature remained below the melting point of gold. Intimate contact between the bonding gold and alumina surfaces during formation of the bond was also an important consideration. This was achieved by using an optically flat and polished ceramic surface and applying a low pressure of about 1 MPa to the bonding couple. Further enhancement of the contact can be achieved by depositing an additional thin layer of gold onto the ceramic surface by evaporation or by other means, and by thorough cleaning by high temperature heat treatment prior to bonding. Good bonding occurs in the range of 1 to 100 h. Bond strengths as high as 80 MPa were achieved.