Method for producing relief image on a metal base

Abstract

The invention relates to producing a relief image on a metal base. The present method includes forming a resist pattern on a surface of a base and etching the sections of the metal which are not covered by the resist. In the present method, copper or an alloy thereof is deposited as a resist on a metal base having an electrode potential that is more negative than the electrode potential of copper, and etching is carried out in a solution that dissolves the parts not covered by the resist primarily as a result of a contact exchange reaction between the metal of the base and the copper ions. The invention makes it possible to improve the quality of the resulting image by means of reducing etchback of a metal base via pores of a resist, and to reduce the cost of producing products.

Claims

1. A method for producing a relief image on a metal base, including a formation of a resist pattern on surface of the metal base and an etching of metal sections, unprotected by the resist pattern, having for the metal base an electrode potential that is more negative than an electrode potential of copper, or copper alloy that is deposited as a resist, and the etching is carried out in a solution containing at least a copper salt of not more than 100 g/l in terms of metal that ensures a dissolution of the metal sections unprotected by the resist primarily as a result of a contact exchange reaction between the metal base and copper ions.

2. A method according to claim 1, wherein areas of the resist that are located more than 2 mm from a resist edge are covered with a chemically resistant material before etching.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(1) Example 1. On a prepared plate made of thin sheet of cold-rolled steel of (Russian steel) grade 08KP (08Π), a resist pattern is formed by contact deposition of copper with a thickness of 3-4 μm. Copper plating solution composition: CuS0.sub.4.5H.sub.20—8-10 g/l, H.sub.2S0.sub.4 (specific gravity 1.84 g/cm3)—80-100 g/l, OP-10 (OΠ-10, Russian surfactant)—8-10 g/l. Solution temperature is 30-35° C. Copper plating duration is 3 min. The areas equidistant from the edge of the resist at a distance of more than 2-2.5 mm are retouched with a chemically resistant varnish. Then the plate is subjected to etching in a solution containing CuCl.sub.2—175-180 g/l at a temperature of 18-25° C. until a relief of the required depth is obtained. For 10 min, the average etching rate was 10 μm/min. The surface of the resist is covered with compact copper, the average deposition rate of copper at a distance from the edge of the relief 1.5-2 mm is about 0.8-1.2 μm/min. The results obtained show that it is of the same order of magnitude as the rate of copper release in conventional galvanic copper plating from sulfate electrolyte at a current density of 4-5 A/dm.sup.2 . Consequently, under conditions of parallel flow of cathodic reactions of contact exchange and internal electrolysis, the current is redistributed in favor of the resist surface. After etching, the sample is washed in water, the varnish is removed with a solvent, and copper is removed in a solution that does not allow etching of the base metal, washed again and dried. Steel without pores, the contour of the relief is clear.

(2) Example 2. The metal of the plate and the technological sequence of manufacturing is the same as in example 1, but instead of copper, an alloy of copper with tin with a thickness of 3-4 μm is deposited, the content of tin is 14-16%. Solution composition: CuS0.sub.4.5H.sub.20—8-10 g/l, H.sub.2SO.sub.4 (specific gravity 1.84 g/cm3)—80-100 g/l, SnSO.sub.4—3-5 g/l, OP-10—3-5 g/l. Solution temperature is 30-35° C. Copper plating duration is 5 min. Steel pickling is carried out in a solution: CuCl.sub.2—175-180 g/l and NaCl—100-120 g/l, at a temperature of 18-25° C. Steel without pores, the contour of the relief is clear.

(3) Example 3. The metal of the plate and the technological sequence of manufacturing are the same as in example 1, but after etching by contact exchange for 5-6 min to a depth of about 0.05 mm, etching is stopped, the workpiece is washed in water and additional etching is carried out in a solution that etches the base metal and does not etch copper: H.sub.2C.sub.2O.sub.4.2H.sub.2O—160-180 g/l, H.sub.2O.sub.2 (30%)—130-150 ml/l, at a solution temperature of 30-35° C., to a relief depth of 0.3 mm. Steel without pores, the contour of the relief is clear.

(4) In accordance with the invention, it has been found that it is possible to combine the etching of a metal base having an electrode potential that is more negative than the electrode potential of copper with the simultaneous deposition of copper on the resist of copper or its alloy, and thus exclude the etching of the base metal under the pores of the resist. This circumstance makes it possible to improve the quality of the processed products in comparison with the existing methods of obtaining a relief and to use a simple and no capital expenditure required immersion method for the deposition of copper or its alloys to create a protective coating on workpieces of various complexity and dimensions.