Method for coating surface of copper wire with tin and a tin-coated copper wire prepared by method

Abstract

The invention relates to the production and processing fields of cables, and particularly relates to a method for coating the surface of a copper wire with tin and a tin-coated copper wire prepared by the method. The invention is realized by the following technical scheme: the method for coating the surface of the copper wire with the tin successively includes the following steps: (1) pretreatment: an annealed bare copper wire is introduced into a cleaning tank with an acid liquid for surface cleaning; (2) tin coating: the pretreated bare copper wire is immerged into a nano liquid for the tin coating, wherein the nano liquid comprises the following components: by weight, 30-35% of tin phosphate, 20-30% of phosphoric acid, 5-10% of citric acid, 5-10% of a mixed surfactant and 30-40% of pure water; (3) neutralization: the tin-coated copper wire is introduced into a neutralization tank with an alkaline liquid; and (4) drying, the neutralized tin-coated copper wire is introduced into a oven for the drying. The method belongs to a cold coating process, and avoids the defects of hot tin-coating processes, and at the same time, is more environmentally friendly in relative to an electroplating process.

Description

technical field [0001] The invention relates to the field of cable production and processing, in particular to a method for tinning the surface of copper wires and tinned copper wires prepared by the method. Background technique [0002] In order to prevent the copper wire from being oxidized and corroded by substances such as sulfides and organic acids, a protective layer is attached to the outer surface of the copper wire, usually a layer of tin is plated. [0003] The conductivity of copper is 100%, while the conductivity of tin is only 14%. In this way, the conductivity of copper wire with tin attached to it is lower than that of bare copper wire, generally 93-94%. Although it does not affect the use of copper wires, it is also a defect in theory. Therefore, this requires that the tin protective layer should have an appropriate and uniform thickness and a tight connection with copper. [0004] Tin plating on the surface of copper wire is generally divided into hot plati...

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Problems solved by technology

[0003] The conductivity of copper is 100%, while the conductivity of tin is only 14%. In this way, the conductivity of copper wire with tin attached to it is lower than that of bare copper wire, generally 93-94%. Although it does not affect the use of copper wires, it is also a defect in theory. Therefore, this requires that the tin protective layer should have an appropriate and uniform thickness and a tight connection with copper.

[0004] Tin plating on the surface of copper wire is generally divided into hot plating and cold plating. The production process of hot plating tin is generally: the material tin is heated to a liquid state in a tin pool, and then the annealed bare copper wire is continuously passed through the tin pool and the tin plating hole. Die, so that the tin layer is attached to the bare copper wire and processed into a smooth and bright tinned copper wire through the eye mold; when the hot-dip tinned copper wire passes through the eye mold, it is necessary to keep the copper wire and the inner hole of the eye mold in a concentric circle as much as possible , to ensure that the thickness of the tin layer is uniform. However, it is almost difficult to achieve in actual operation, and the tin layer on the copper wire is loose, and the tin powder is easy to fall off. During the production process of copper wire, the eye mold is often blocked. In addition, since the copper wire can only be formed into a line after passing through the liquid tin pool and passing through the eye mold, the walking resistance of the copper wire is increased on the long and multi-turn tinning equipment, and the increased resistance of the line is easy to cause annealing. The final copper wire is thinned and elongated, and when producing small tinned copper wires with a diameter of 0.08mm and below, the copper wire is easily burned in the tin pool

[0005] Cold tinning process, such as a kind of electroplating tinning method disclosed in the invention patent application with the publication number CN1993502A, includes: the first process, when adjusting the blowing amount of oxygen to control the generation rate of tin ions, according to the plate passing The progress of obtaining the tin ion predetermined consumption rate with time variation; the second process, according to the tin ion predetermined consumption rate with time change, every predetermined time to the tin ion generation rate is divided, will be in each The averaged tin ion generation rate in the divided intervals is set as the average change over time; The concentration becomes the tin ion generation rate that does not exceed the upper limit of the control target and the lower limit of the control target in the above-mentioned intervals; through the principle of electroplating, the tin is plated on the surface of the copper wire, avoiding the molten tin pool and eyes required for hot-dip tinning. There will be no defects of hot-dip tinning, but the process of electro-tinning is easy to produce industrial wastewater and pollute the environment

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