Patent ID: 7816015

Claim:
A composite copper foil, comprising three layers comprising a support metal layer, a release layer lying on the support metal layer, and a thin copper layer lying on the release layer, wherein: (1) the release layer comprises a tungsten alloy and a metal oxide containing tungsten, has one surface formed mainly of the tungsten alloy and the other surface formed mainly of the metal oxide containing tungsten, has a content of the tungsten alloy decreasing continuously from the surface formed mainly of the tungsten alloy toward the surface formed mainly of the metal oxide containing tungsten, and has a content of the metal oxide containing tungsten decreasing continuously from the surface formed mainly of the metal oxide containing tungsten toward the surface formed mainly of the tungsten alloy; or (2) the release layer comprises a molybdenum alloy and a metal oxide containing molybdenum, has one surface formed mainly of the molybdenum alloy and the other surface formed mainly of the metal oxide containing molybdenum, has a content of the molybdenum alloy decreasing continuously from the surface formed mainly of the molybdenum alloy toward the surface formed mainly of the metal oxide containing molybdenum, and has a content of the metal oxide containing molybdenum decreasing continuously from the surface formed mainly of the metal oxide containing molybdenum toward the surface formed mainly of the molybdenum alloy.