Wiring substrate

Abstract

A technique for suppressing generation of a crack in a joint portion of a wiring substrate is provided. The wiring substrate includes: a ceramic substrate formed of a ceramic material and having wiring; a metallic member which includes a base member containing a first metal and a protection film containing a second metal different from the first metal and covering a surface of the base member; and a joining layer which contains the first metal disposed between the ceramic substrate and the metallic member, and joining the ceramic substrate and the metallic member to each other. In a region between the joining layer and the base member, the protection film is broken and discontinuous, and the joining layer and the base member are directly joined to each other.

Dependencies are inferred from the claim text.