Support layer for thin copper foil
A composite material useful for the manufacture of a circuit has a support layer, a metal foil layer having opposing first and second sides and a thickness of 15 microns or less and a release layer effective to facilitate separation of the metal foil layer from the support layer, the release layer disposed between and contacting both the support layer and the metal foil layer. A reactive element containing layer, which may be the support layer, effective to react with gaseous elements or compounds to form thermally stable compounds contacts the release layer. The composite material is preferably subjected to a low temperature heat treatment. The combination of the low temperature heat treatment and the reactive element containing layer results in reduced defects including blisters in the copper foil during subsequent processing.
1. A composite material, comprising:
a support layer;
a metal foil layer having opposing first and second sides and a thickness of 15 microns or less;
a release layer effective to facilitate separation of said metal foil layer from said support layer, said release layer disposed between said support layer and said metal foil layer and contacting said metal foil layer; and
a reactive element containing layer disposed between and contacting both said release layer and said support layer, wherein said reactive element containing layer contains a reactive element selected from the group consisting of titanium, zirconium, barium, magnesium, silicon, niobium, calcium and mixtures thereof.
2. The composite material of claim 1 wherein said reactive element containing layer has a thickness of from 10 Å to 2 μm.
3. The composite material of claim 2 wherein said support layer is a wrought, copper-base, material having a yield strength in excess of 30 ksi following a thermal exposure of from 100° C.–350° C. for up to 48 hours.