FLUX-FREE METHOD FOR PRODUCING TINNED COPPER WIRE COATED WITH AN ALLOY BASED ON TIN AND INDIUM Russian patent published in 2022 - IPC C23C28/02 C23C2/08 C25D3/60 

FIELD: wire production.

SUBSTANCE: invention relates to the production of tinned copper wire. The method includes degreasing copper wire, washing in demineralized water, obtaining a first microscopic adhesive layer of an alloy of tin and indium, obtaining a second layer by immersion in an alloy based on tin and indium, drying in air. The first layer is obtained by electrochemical deposition at a temperature of 20-35°C, a cathodic current density of 20-80 A/dm² with a current efficiency of 95-98% in an electrolyte containing tin sulfate, sulfuric acid and a copolymer of dimethicone and polyethylene glycol, indium sulfate, isopropyl alcohol, glycerin. The second layer is obtained by dipping the wire into a tin-indium-based alloy melt, in which the wire is pulled through the tin-indium-based alloy melt in a tinning bath at a speed of 140-260 m/min at a temperature of the tin-indium-based solder melt 80-120°C, and remove excess melt from its surface by pulling through a die with a diameter of 265-310 microns. The thickness of the first layer of tin and indium is 0.1-1.0 microns, and the thickness of the second layer of tin and indium is 2.5-5 microns, while the ratio of the coating thickness to the diameter of the wire is 0.02-0.04.

EFFECT: obtaining a tinned copper wire with a coating of the required thickness, uniformity, density and with an indium content of 40-52 wt. % sufficient for soldering the electrodes of solar modules and ensuring reliable electrical contact with the silver-containing contact grid.

1 cl, 1 tbl, 7 ex