Importance

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Abstract

This invention provides a composite foil comprising an aluminum carrier layer and an ultra-thin copper foil having a protective layer disposed between them comprising a porous copper layer and an interpenetrating zinc layer. A process for producing such composite foils comprises the steps of preparing the surface of the aluminum carrier, electrodepositing a porous copper layer on the aluminum carrier layer followed by electrodepositing a zinc layer, and then electrodepositing two layers of copper to form the ultra-thin copper foil. The composite foil provides a uniform bond strength between the aluminum carrier and the protective layer which is adequate to prevent separation of the carrier and ultra-thin copper foil during handling and lamination, but which is significantly lower than the peel strength of a copper/substrate bond, so that the carrier can easily be removed after lamination of the composite foil to an insulating substrate. The invention also includes laminates made from such composite foils and printed wiring boards made from such laminates.

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First Claim