Cold Sintering Process for Fabrication of a Ceramic Substrate with the Copper Layer

The cold sintering process (CSP) is a low-temperature sintering technique of ceramics. In this work, the ceramic substrates were fabricated by the cold sintering process of the alumina powder and sodium silicate solution. And the forming pressures of cold sintering ceramic substrate were investigated. When the ceramic substrates were fabricated and compared, the results showed that the alumina of ceramic substrate molded under 200 MPa presents the closest accumulation, which the relative density is 88.7% and the porosity of the ceramic is only 14.2%. The mass loss of ceramic molded under 200 MPa is 1.45% when heated to 800℃, and the thermal expansion coefficient is only 12.9×10
^-6
/℃ from 30 ℃ to 400 ℃. In addition, the ceramic substrate with the copper layer is prepared by forming copper sheet and alumina slurry together by CSP, which the bonding strength of copper and ceramic substrate is as high as 7.1 MPa. After electroplating graphics, the bonding strength of ceramic substrate is not affected by electroplating process, and the bonding strength is still stable at 6.2 MPa.