Upper cover for packaging, preparation method thereof and resonator comprising upper cover

The invention belongs to the technical field of electronic component packaging, and particularly relates to an upper cover for packaging, a preparation method of the upper cover and a resonator comprising the upper cover. The upper cover comprises a sheet-shaped kovar base material, a nickel layer is arranged on the upper surface of the kovar base material, a silver-copper alloy layer is arranged on the lower surface of the kovar base material, and the outer surface of the kovar base material is coated with a nickel-phosphorus alloy layer. According to the multi-layer composite metal cover plate, the nickel and the silver-copper alloy are thermally compounded on the upper surface and the lower surface of the Kovar base material respectively, and then the nickel-phosphorus alloy layer is plated on the surface after punch forming, so that the subsequent welding melting of the upper cover and the ceramic base mainly occurs on the silver-copper alloy layer, and due to low melting point and less heat required by w