CHEMICAL ETCHING METHOD OF SEMICONDUCTOR LEAD FRAME

摘要

PURPOSE: A method for chemically etching a semiconductor lead frame is provided to obtain a correct width of a silver plating layer with a high etch rate and without damaging a photo resist film used for etching. CONSTITUTION: In manufacture of the lead frame for a semiconductor package, the silver plating layer is formed on copper alloy or nickel alloy and then chemically etched to form a pattern. During the chemical etching, the silver plating layer is selectively removed by supplying a solution with pH scale of 3.0-7.0 at a temperature of 40-80°C in a deposition or injection manner. The solution includes at least one oxidizing agent and a complexing agent. The oxidizing agent is selected from the group consisting of 0.02-0.2M ferricyanide alkali metal, 0.01-0.5M persulphate alkali metal and 0.01-05M thiocyanate alkali metal. The complexing agent is preferably 1-4M iodic alkali metal. The chemical etching method is useful to manufacture a fine pitch lead frame.