CERAMICS-METAL COMPOSITE BODY AND METHOD OF PRODUCING THE SAME

摘要

A composite substrate 30 comprises an alumina substrate 16, a metal layer 34 and a copper plate 26 bonded to the alumina substrate 16 through the metal layer 34. The metal layer 34 comprises a tungsten layer 34a having a low thermal expansion coefficient, a mixed layer 34b of tungsten and a silver-copper alloy, and a silver-copper alloy layer 34c having a high thermal expansion coefficient. In the mixed layer 34b, the ratio of silver-copper alloy content to tungsten content progressively increases as portion of the layer is gradually away from the alumina substrate 16.