Laminate

1. A laminate comprising a metallic base material, a nickel-containing plating film layer formed on the metallic base material, and a gold plating film layer formed on the nickel-containing plating film layer,

wherein pinholes in the gold plating film layer are sealed with a passive film having a thickness of 15 nm or greater,

wherein the passive film is formed on a surface of the nickel-containing plating layer by forcible oxidation of the nickel-containing plating layer.

2. The laminate according to claim 1 , wherein the metallic base material comprises at least a metal selected from the group consisting of stainless steel, iron, aluminum, aluminum alloys, copper, and copper alloys.

3. The laminate according to claim 1 , having a nickel strike layer between the metallic base material and the nickel-containing plating film layer.

4. The laminate according to claim 1 , wherein the nickel-containing plating film layer comprises a nickel-phosphorus alloy plating layer (1) having a phosphorus concentration of 8% by mass or higher and lower than 10% by mass, and a nickel-phosphorus alloy plating layer (2) having a phosphorus concentration of 10% by mass or higher and 12% by mass or lower in this order from the metallic base material.

5. The laminate according to claim 1 , wherein the gold plating film layer comprises a displacement gold plating film layer and a reduction gold plating film layer in this order from the nickel-containing plating film layer.

6. A constituent member of a semiconductor production device, made up of the laminate according to claim 1 .