Copper foil with low profile bond enhancement

Abstract

A composite material, comprising a carrier strip the carrier strip comprising a first side the first side comprising a substantially uniform roughness, an electrolytically deposited copper foil layer having opposing first and second sides and a thickness of from 0.1 micron to 15 microns and the entire metal foil layer thickness having been deposited from a copper containing alkaline electrolyte, and a release layer effective to facilitate separation of the metal foil layer from the carrier strip disposed between and contacting both the first side of the carrier strip and the second side of the metal foil layer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This patent application is a continuation-in-part of U.S. patent application Ser. No. 09 / 784,547 entitled “Copper Foil With Low Profile Bond Enhancement” by Szuchain Chen, et al. that was filed Feb. 15, 2001. This patent application relates to U.S. patent application Ser. No. 09 / 522,544 entitled “Copper Foil Composite Including a Release Layer” by Szuchain Chen, et al. that was filed on Mar. 10, 2000. The disclosures of both U.S. patent application Ser. Nos. 09 / 784,547 and 09 / 522,544 are incorporated by reference in their entireties herein.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to a composite material having an intervening release layer. More particularly, a copper foil layer is releasably bonded to a carrier layer for transport and assembly. The release layer disposed between the carrier layer and the copper foil layer facilitates separation. The copper foil layer may be laminated to ...

AI Technical Summary

Benefits of technology

"The invention provides a thin metallic foil that is releasably attached to a carrier layer, which can be easily separated from the carrier layer without damaging the foil. The foil is a thin copper foil that is useful for manufacturing printed circuit boards and flexible circuits. The method for manufacturing the foil / carrier layer composite is environmentally friendly compared to previous methods. The foils have a smooth surface, which reduces surface roughness and improves imaging and fine line capability in circuit manufacturing. The composite material can be directly laminated onto a dielectric substrate and separated from the carrier layer at the release layer. The metal foil layer can then be formed into a plurality of electrically isolated circuit traces."

Problems solved by technology

While the vertical etching is required to create spaces between adjacent circuit traces for electrical isolation, horizontal etching at the sides of a trace damages the integrity of the circuit traces.

Another problem with thicker copper foil is that a longer time is required to etch the foil increasing the manufacturing cost and increasing the environmental concern due to the disposal or reclamation of dissolved copper.

Yet another problem arises from the presence of Ni / Au overhang.

When a thick copper foil coated with with Ni / Au is etched, the etch undercut can be severe resulting in breakage of the Ni / Au overhang and possibly causing a short circuit in the finished product.

Etching is time-consuming and disposal may create environmental problems.

While a generally acceptable process, areas of unacceptable high adhesion may occur when a chrome phosphate release layer is formed directly on a copper alloy carrier.

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