• Removes oxidation to facilitate soldering
• Easily cleaned in water
• Minimal Etching

Kester 5520 Copper-Nu is a non-fuming liquid solution for removing oxides, sulfides, carbonates and other contamination, such as etch residues, from copper metal surfaces to facilitate soldering. This stable solution cleans by dissolving or solubilizing the contamination for easy removal by water rinsing. The chemical cleaning action is quite different form strong mineral acids which etch away valuable base metal and passivate the surface by insoluble film formation. Kester 5520 contains a pink pH indicator which turns yellow at pH 3.5 indicating the solution has lost its efficiency. Because the etch rate is controlled, the bath life is very extended. Kester 5520 will selectively remove surface contamination from copper or gold-plated surfaces with no appreciable metallic etching.

RoHS Compliance
This product meets the requirements of the Restriction of Hazardous Substances (RoHS) Directive, 2015/863 for the stated banned substances.

Flux Application
Surfaces to be cleaned should be free of oil and grease. 5520 should be used as received in plastic or glass containers at room temperature or hot 49 to 60 °C (120 to 140 °F). Heating the solution accelerates the rate at which Copper Nu reacts with contaminants. Parts are immersed for 30 seconds to 3 minutes depending on the condition of the surface and then water is rinsed to remove the solubilized contamination. Residual water-insoluble metallic complexes can be removed from an etched surface with minimal etching of the metal. Plating or etching residues can seriously affect the reliability of a soldered connection.

Cleaning
No neutralizer, saponifiers, or detergents are necessary in the water wash system for the complete removal of residues. It is not recommended to use high mineral content tap water. Otherwise, tap, deionized or softened water may be used for cleaning.