Patent ID: 8448842

Claim:
An advanced copper bonding (ACB) method for joining copper to a ceramic substrate, the method comprising the steps of: i) depositing a copper film on at least one of two opposing surfaces of a ceramic substrate in a sputtering machine to form a copper dielectric layer on at least one of two opposing surfaces of said ceramic substrate; and ii) preparing a copper foil ( 4 ) and pressing said copper foil ( 4 ) on said ceramic substrate ( 1 ) and then putting said copper foil ( 4 ) with said ceramic substrate ( 1 ) in a high-temperature sintering furnace at a pressure ≦1 atmosphere pressure to let said copper dielectric layer and said copper foil ( 4 ) be bonded into a copper strip ( 41 ) by a diffusion bonding technique where diffusion between the surface of said copper strip ( 41 ) and atoms of said ceramic substrate ( 1 ) causes formation of a bonding layer ( 5 ) so that said copper strip ( 41 ) and said ceramic substrate ( 1 ) are tightly bonded together, forming a composite plate, wherein said ceramic substrate is prepared by sintering aluminum trioxide or aluminum nitride under an atmosphere pressure or non-oxygen high temperature environment, said non-oxygen high temperature environment being at a temperature of 1900° C., wherein a copper dielectric layer is formed on each of the two opposing surfaces of said ceramic substrate, wherein formation of the copper film on at least one of two opposing surfaces of said ceramic substrate ( 1 ) in said sputtering machine is done under the conditions of operating temperature about 150° C. and vacuum about 1.33×10 −3 torr and the thickness of said copper film is smaller than 1 μm, the method further comprising a sub step of electroplating a copper layer on said copper film prior to putting said copper foil ( 4 ) with said ceramic substrate ( 1 ) in said high-temperature sintering furnace, enabling said copper layer and said copper film to form a copper dielectric layer having a thickness within 10˜50 μm.