[0050] A detailed description of the specific implementation of the present invention is given below.
[0051] A production process of tinned copper-clad steel includes the following steps in sequence:
[0052] (1) For rough drawing of steel wire, the base material of steel wire with a diameter of 5.5-6.5mm is stripped and bristled to remove the oxide layer, then expanded and dried, and then drawn into a straight wire drawing machine to a wire diameter of 3.2-3.6mm;
[0053] (2) Steel wire fine drawing, the steel wire after rough drawing is put into the straight wire drawing machine and drawn to a steel wire with a diameter of 1.4-2.0mm;
[0054] (3) Ammonia decomposition heat treatment of steel wire. Put the drawn steel wire into a vacuum tempering furnace for ammonia decomposition heat treatment. The tempering temperature of hard products is between 430℃-470℃, and the tempering temperature of soft products is 720-800. ℃, the soft product is copper-clad steel with a tensile strength of 300-400MPa, and the hard product is copper-clad steel with a tensile strength of 800-1000MPa. The ammonia decomposition and tempering process can prevent the steel wire from oxidation after drawing , The use of ammonia decomposition and tempering process can prevent the steel wire from oxidation after drawing;
[0055] (4) Pretreatment of copper plating: ①Pick the heat-treated steel wire with hydrochloric acid solution on-line to remove stains on the surface of the steel wire; ②Rinse the steel wire after pickling with clean water to remove the residue on the surface of the steel wire due to the pickling process Pickling liquid
[0056] (5) Acid electrolysis: ①The pre-treated steel wire is subjected to acid electrolysis with a dilute sulfuric acid solution to further remove stains on the surface of the steel wire and activate the surface of the steel wire, ②The steel wire after acid electrolysis is then washed with water to remove the steel wire Acid solution remaining on the surface due to the acid electrolysis process;
[0057] (6) Pre-plating copper, the steel wire after washing is pre-plated with non-cyanide alkali copper to produce copper-clad steel conductor, the current density of pre-plating is 1-1.5A/dm 2 , The thickness of the copper layer is controlled within 0.5-1 microns, and then the copper-clad steel after pre-plating copper is washed with water to remove the plating solution remaining on the surface of the steel wire due to the pre-plating;
[0058] (7) Thick copper plating. The washed copper-clad steel is subjected to further sulfate thick copper plating to produce copper-clad steel conductors with a current density of 10-15A/dm. 2 , The thickness of the copper layer is controlled within 25-35 microns;
[0059] (8) Cold and hot passivation, cold passivation and heat passivation are performed on the copper-clad steel with an antioxidant to prevent oxidation of the copper-clad steel. The antioxidant is benzotriazole, which is dissolved in alcohol and prepared by adding water Passivation solution, the concentration of the passivation solution is 0.5%-0.7%, cold passivation is normal temperature passivation, and the temperature of hot passivation is 45℃-70℃;
[0060] (9) Drying, drying the passivated copper clad steel;
[0061] (10) Water tank drawing, the thick copper-plated copper-clad steel is moved into the water tank drawing machine and drawn to a copper-clad steel with a diameter of 0.4-1.0mm;
[0062] (11) Alkaline electrolysis before nickel plating, the above-mentioned copper-clad steel with a diameter of 0.4-1.0mm is subjected to alkaline electrolysis, the alkaline electrolysis current is 1-2 amperes, and the concentration of lye is controlled at 5%-10% to remove the copper-clad steel The surface of the copper-clad steel after the alkaline electrolysis is rinsed with water to remove the residual lye on the surface of the copper-clad steel due to the residual lubricant during drawing;
[0063] (12) Acid electrolysis before nickel plating, the copper clad steel after alkaline electrolysis is electrolyzed with dilute sulfuric acid solution, the acid electrolysis current is 1-2 amperes, the sulfuric acid concentration is controlled at 4%-6%, and the surface of the copper clad steel is removed. Then, the copper-clad steel after acid electrolysis is washed with water to remove the residual acid on the surface of the copper-clad steel due to acid electrolysis;
[0064] (13) Nickel plating: the copper-clad steel after acid electrolysis is nickel-plated with sulfate, with nickel sulfate as the main salt, with a concentration of 250-300g/l; nickel chloride as an activator, with a concentration of 40-50g/l; Boric acid is used as a buffer, and the concentration is 30-40g/l. Add surfactants as the main additive to improve the throwing power and coverage of the bath. Commonly used additives are sodium lauryl sulfate or OP-10 ,Plating a layer of nickel with a thickness of 1-2 microns on the surface of the copper-clad steel, and then wash the nickel-plated copper-clad steel with water to remove the residual nickel plating solution on the surface due to nickel plating;
[0065] (14) Tin plating, the nickel-plated copper clad steel is subjected to sulfate tin plating or methane sulfonate tin plating to produce nickel-plated copper clad steel;
[0066] (15) Alkali neutralization, the above-mentioned tin-plated nickel-plated copper-clad steel is alkali-neutralized with trisodium phosphate or sodium carbonate to remove the acidic tin plating solution remaining on the surface;
[0067] (16) Washing and drying, the tinned copper-clad steel after alkali neutralization is washed with water to remove the residual alkali neutralizing liquid on the surface, and then dried to avoid oxidation on the surface of the tinned copper-clad steel conductor due to adhesion of moisture;
[0068] (17) Polishing. The dried tinned copper clad steel is moved into the drawing machine for polishing to produce a bright tinned copper clad steel product;
[0069] (18) Take up the wire and pack it into reel, and wrap the finished tin-plated copper clad steel with a suitable plastic reel or paper drum.
[0070] The copper layer of the traditional tin-plated copper clad steel often produces some minor quality problems during the electroplating and drawing process, such as burrs, sand holes, oxidation, and black spots. These problems will affect the solderability of the finished product, and cause oxidation, In the case of blackening, the addition of a nickel layer between the copper layer and the tin layer can cover these defects of the copper layer and improve the high temperature solderability of tinned copper clad steel. The tin layer does not directly contact the copper layer, preventing the copper layer Mutual diffusion with the tin layer, thereby improving the solderability, and the thermal conductivity of nickel is lower than that of copper, which increases the heat resistance, thereby improving the high temperature soldering performance and high temperature resistance of tinned copper clad steel. The traditional The tin-plated copper-clad steel generally can only pass 420 degrees high-temperature soldering. The temperature of the tin-plated copper-clad steel with the nickel layer added with the above technical scheme can reach 480 degrees. The traditional tin-plated copper-clad steel wire is placed After half a year, there will be oxidation, sometimes even less than half a year, the tinned copper clad steel wire after nickel plating will not be oxidized within 7 months, the traditional tinned copper clad steel wire The aging resistance and high temperature resistance are poor. Generally, the surface does not turn yellow for two hours at 160 degrees. The tin-plated copper clad steel with nickel layer using the above technical scheme can reach 180 degrees without yellowing for two hours.