US Patent 11177186 Bonded body and insulated circuit board

A bonded body is formed by bonding a ceramic member formed of an Al-based ceramic and a copper member formed of copper or a copper alloy, in which, in a bonding layer formed between the ceramic member and the copper member, a crystalline active metal compound layer formed of a compound including an active metal is formed on a ceramic member side, and, the Al concentration is 0.15 at % or less in a thickness range of 0.5 μm to 3 μm from an interface of the active metal compound layer on a copper member side toward the copper member.