Copper foil for printed circuit board and its surface treatment method

Abstract

Disclosed is a copper foil-for printed circuit boards-which is especially excellent in soft etching property and also superior in such properties as heat discoloration resistance, rust-proofing and solder-ability. The copper foil for printed circuit boards comprising a first layer formed by applying 12 to 50 mg/m2 of a sulfur-contained zinc alloy containing 0.1 to 2.5 percent by weight of sulfur on the surface on at least one side of the copper foil and a second layer formed of a chromate layer on the first layer by applying 0.5 to 2.5 mg/m2 of chromium and, if necessary, 1.5 to 6 mg/m2 of phosphorus. The process of treating the surface of copper foil for printed circuit boards comprising the steps of forming the first layer composed of a sulfur-contained zinc alloy by electrolysis by dipping at least the surface on one side of the copper foil in a solution containing a zinc compound and a sulfur compound and forming the second layer composed of chromate by electrolysis by dipping said first layer in a solution containing a chromium compound, or a chromium compound and a phosphorus compound.

Description

technical field [0001] The present invention relates to a copper foil for printed circuit boards, more specifically, in the application of conductive materials represented by printed circuit boards, the surface treatment of copper foil to make the rough surface uniform Due to its high adhesion, it is suitable for use as copper foil for printed circuit boards and its surface treatment method. Background technique [0002] Printed circuit boards are widely used in electronic and electrical materials, and the development of high-performance and high-reliability technologies requires materials to have increasingly complex and diverse characteristics. As one of the constituent materials of the printed circuit board, Copper foil, its quality requirements are also strict. [0003] In the manufacturing process of printed circuit boards, the rough side of the copper foil is first laminated with a base material impregnated with insulating synthetic resin, laminated, and hot-pressed w...

AI Technical Summary

Problems solved by technology

[0015] However, in none of the above-mentioned methods, the surface of the copper foil in a uniform roughened state was obtained by growing the unevenness by soft etching, and the adhesion force could not be fully exerted by the subsequent blackening treatment, and no improvement was directly proposed. soft etch method

[0016] Furthermore, although the mixture coating of Zn or zinc oxide and chromium oxide disclosed in Japanese Patent Publication No. 58-7077 has excellent solder wettability, its thermal discoloration resistance and rust resistance are poor due to insufficient coating thickness.

However, the surface of the copper foil prepared by chromate treatment after the formation of the Zn-Ni alloy layer disclosed in the patent 2517503 has solder wettability problems.