Copper-clad aluminum wire rod for photovoltaic welding strip bus bar and preparation method of copper-clad aluminum wire rod

Abstract

The invention relates to the technical field of cable production, in particular to a preparation method of a copper-clad aluminum wire rod for a photovoltaic welding strip bus bar, which comprises the following steps of: carrying out alkali washing and fluoride-free acid washing to obtain an aluminum wire subjected to fluoride-free acid washing; anodic oxidation: carrying out anodic oxidation treatment on the aluminum wire subjected to fluoride-free acid pickling in a phosphoric acid solution, and washing with water to obtain a wire rod; copper plating is conducted, specifically, the wire is placed in the electroplating solution for copper plating, the electroplating temperature ranges from 25 DEG C to 30 DEG C, and the electroplating time ranges from 5 min to 8 min under the condition that the current density ranges from 1 A / dm < 2 > to 2 A / dm < 2 >; copper sulfate and hydrogen peroxide are added into the electroplating liquid, the electroplating temperature is adjusted to be 40-55 DEG C, electroplating is conducted for 30-35 min under the current density of 2-4 A / dm < 2 >, and electroplating is conducted for 5-8 min under the current density of 1-2 A / dm < 2 >; and stretching and annealing the copper-plated wire rod for a plurality of times to obtain the copper-clad aluminum wire rod. Compared with the prior art, the copper-clad aluminum wire which is high in copper content and good in performance is obtained through the preparation method, and the performance of the wire meets the performance requirement of a photovoltaic welding strip bus bar.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular to a copper-clad aluminum wire for photovoltaic welding strip busbar and a preparation method thereof. BACKGROUND

[0002] The photovoltaic welding strip busbar plays a key role in connecting the battery pieces and conducting current in the photovoltaic module. Traditionally, the busbar is mostly made of pure copper material, which has excellent electrical conductivity, but has the problems of high cost, heavy weight and cannot meet the development of lightweight products. In order to reduce the production cost and weight and develop lightweight products, copper-clad aluminum wire is proposed as a substitute material for pure copper wire. However, the existing copper-clad aluminum wire has the following problems: Firstly, there are deficiencies in the thickness control of the copper layer, the design of the aluminum core diameter and the copper-aluminum bonding strength, which affect the application effect in the photovoltaic module; Secondly, the copper-aluminum thermal expansion coefficient difference is large, and the metallurgical bonding between copper and aluminum is poor, so the interface is easy to produce thermal stress under temperature cycle, and delamination and micro-cracks occur, resulting in poor product quality or short service life; Thirdly, the copper content of copper-clad aluminum is too low, and the aluminum core is easy to be exposed, false welding and welding-off during welding, which affects the yield and long-term reliability of the module.

[0003] Due to the above problems, the existing copper-clad aluminum wire has poor effect for photovoltaic welding strip busbar. SUMMARY

[0004] The purpose of the present application is to provide a copper-clad aluminum wire for photovoltaic welding strip busbar and a preparation method thereof, which aims to overcome the technical problems existing in the background art.

[0005] To achieve the above purpose, the present application provides a preparation method of a copper-clad aluminum wire for photovoltaic welding strip busbar, which comprises: S1, alkali washing: soaking the aluminum wire in an alkali washing solution, washing with water to obtain an alkali washed aluminum wire; S2, fluoride-free acid washing: soaking the alkali washed aluminum wire in a fluoride-free acid washing solution, washing with water, neutralizing to obtain a fluoride-free acid washed aluminum wire; S3, anodic oxidation: anodizing the fluoride-free acid washed aluminum wire in a phosphoric acid solution, washing with water to obtain a wire; S4, copper plating: placing the wire in an electroplating solution for copper plating, the temperature of electroplating is 25-30℃, the current density is 1-2A / dm 2 The lower electroplating time is 5-8min; copper sulfate and hydrogen peroxide are added to the electroplating solution, the temperature of electroplating is adjusted to 40-55℃, the current density is 2-4A / dm 2The electroplating is performed for 30-35 min at a current density of 1-2 A / dm 2 The electroplating is performed for 5-8 min, wherein the electroplating solution comprises 180-200 g / L copper sulfate, 40-50 g / L sulfuric acid, 55-65 g / L sodium sulfate, 1-2 g / L sodium chloride, 0.1-0.3 g / L 2-mercaptobenzimidazole, 0.1-0.3 g / L ethylenethiourea, 5-10 g / L sodium polydithiobisphenyl sulfone, 10-15 g / L polyethylene glycol, 0.01-0.05 g / L alkyl imidazoline quaternary ammonium salt, 0.01-0.05 g / L diethanolamine, and 0.05-0.1 g / L bipyridine. S5, the copper-plated wire is stretched and annealed several times to obtain the copper-coated aluminum wire.

[0006] Preferably, in the above technical solution, in the step of fluorine-free acid washing, the step of immersing the alkali-washed aluminum wire in a fluorine-free acid washing solution, washing with water, neutralizing, and obtaining a fluorine-free acid-washed aluminum wire is specifically as follows: S21, immersing the alkali-washed aluminum wire in a fluorine-free acid washing solution for 70-80 s; S22, washing the fluorine-free acid-washed aluminum wire with hot water and cold water; S23, immersing the water-washed aluminum wire in a neutralizing solution for 25-30 s to obtain a fluorine-free acid-washed aluminum wire.

[0007] Preferably, in the above technical solution, the fluorine-free acid washing solution comprises 180-190 g / L phosphoric acid, 90-100 g / L sulfuric acid, 55-65 g / L sodium vinyl sulfonate, 10-15 g / L alkyl imidazoline quaternary ammonium salt, 10-15 g / L diethanolamine, 15-20 g / L hydrogen peroxide, 10-15 g / L potassium persulfate, 40-50 g / L sodium nitrate, 1-3 g / L sodium dodecyl benzene sulfonate, and 5-10 g / L carboxymethyl cellulose.

[0008] Preferably, in the above technical solution, the neutralizing solution is 0.5-1% sodium carbonate or 0.5-1% ammonia water.

[0009] Preferably, in the above technical solution, in the step of anodizing, the anodizing treatment condition is anodizing for 10-15 min at a current density of 1-2 A / dm 2 and a temperature of 25°C.

[0010] Preferably, in the above technical solution, in the step of anodizing, the phosphoric acid solution comprises 300-420 g / L phosphoric acid, 1-2 g / L sulfuric acid, 1-2 g / L sodium dodecyl sulfate, and 1-2 g / L oxalic acid.

[0011] Preferably, in the technical solution above, the alkaline solution is a 40-50 g / L sodium hydroxide solution.

[0012] Preferably, in the technical solution above, the phosphoric acid solution comprises 300-420 g / L phosphoric acid, 1-2 g / L sulfuric acid, 1-2 g / L sodium dodecyl sulfate, and 1-2 g / L oxalic acid.

[0013] Preferably, in the technical solution above, the step of subjecting the copper-plated wire to multiple stretching and annealing treatments to obtain the copper-clad aluminum wire is specifically as follows: After the copper-plated wire is subjected to normal-temperature drawing, it is annealed at 400-450 DEG C for 3-4 hours, then subjected to normal-temperature drawing again, and annealed at 450-550 DEG C for 3-4 hours.

[0014] A copper-clad aluminum wire for a photovoltaic soldering ribbon busbar is prepared by a preparation method, and the copper content is 40-50%.

[0015] Compared with the prior art, the present application has the following advantages: (1) The preparation method of the present application has the following principles for improving the copper-aluminum bonding strength and controlling the copper layer thickness: first, the combination of alkali washing and fluoride-free acid washing removes the protective film on the surface of the aluminum wire, and then anodic oxidation treatment forms a uniform and adherent anodic oxide film; second, the uniform and adherent anodic oxide film improves the metallurgical bonding between the copper plating layer and the aluminum core during copper plating, thereby avoiding the separation and micro-crack phenomenon after use; finally, controlling the copper plating solution and the copper plating process realizes uniform copper plating and a copper content of 50%, thereby avoiding the aluminum core during welding, and the performance of the obtained wire is improved through multiple stretching and annealing.

[0016] (2) The components of the fluoride-free acid washing solution and the soaking time are adjusted to ensure that the oxide film on the surface of the aluminum wire is mostly removed and the corrosion resistance is enhanced, thereby protecting the aluminum core matrix from excessive corrosion.

[0017] (3) By controlling the current density, temperature, time, and phosphoric acid solution of the anodic oxidation treatment, the anodic oxide film formed on the surface of the aluminum material has excellent high nanopore abundance and high activity. The anodic oxide film serves as a medium layer between the copper plating layer and the aluminum core, and during copper plating, the oxide anode and copper are connected through hydrogen bonds and oxygen bridge bonds, thereby enhancing the mechanical anchoring strength of the copper plating layer and the aluminum core, improving the thermal expansion coefficient of the copper-clad aluminum wire, and further promoting the metallurgical bonding between copper and aluminum through stretching and annealing, thereby avoiding the interface brittleness problem.

[0018] (4) Finally, the wire is subjected to multiple stretching and annealing to promote interatomic diffusion of copper and aluminum in the medium layer, further improve the mechanical anchoring strength of the bonding surface between the copper plating layer and the aluminum core, improve the thermal expansion coefficient of the copper-clad aluminum wire, and avoid the separation and micro-crack phenomenon at the interface due to the large difference in the thermal expansion coefficients of copper and aluminum during use. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention. Example 1

[0020] A method for preparing a copper-clad aluminum wire for a photovoltaic welding ribbon busbar, the method comprising: S1, alkali washing: immersing the aluminum wire in an alkali washing solution for alkali washing, and then washing with water to obtain an alkali-washed aluminum wire; S2, fluorine-free pickling: soaking the alkali-washed aluminum wire in a fluorine-free pickling solution, washing with water, and neutralizing to obtain the fluorine-free pickling aluminum wire. S21, soaking the alkali-washed aluminum wire in a fluorine-free acid cleaning solution for 70-80 seconds, wherein the fluorine-free acid cleaning solution comprises 180-190 g / L phosphoric acid, 90-100 g / L sulfuric acid, 55-65 g / L sodium vinyl sulfonate, 10-15 g / L alkyl imidazoline quaternary ammonium salt, 10-15 g / L diethanolamine, 15-20 g / L hydrogen peroxide, 10-15 g / L potassium persulfate, 40-50 g / L sodium nitrate, 1-3 g / L sodium dodecylbenzene sulfonate, and 5-10 g / L carboxymethyl cellulose; S22, washing the aluminum wire after the fluorine-free acid washing with hot water and cold water; S23, soaking the washed aluminum wire in 1% sodium carbonate for 25-30 seconds to obtain a fluorine-free acid-washed aluminum wire; S3, anodizing: the aluminum wire after fluorine-free pickling is placed in a phosphoric acid solution at a current density of 1A / dm 2 , anodizing at a temperature of 25° C. for 10-15 minutes, and washing the anodized wire with water to obtain a wire, wherein the phosphoric acid solution comprises 350 g / L phosphoric acid, 1 g / L sulfuric acid, 1 g / L sodium lauryl sulfate, and 1 g / L oxalic acid; S4, copper plating: Place the wire in the electroplating solution for copper plating. The electroplating temperature is 25-30℃ and the current density is 1-2A / dm 2 The electroplating time is 5-8min; copper sulfate and hydrogen peroxide are added to the electroplating solution, the electroplating temperature is adjusted to 40-55℃, and the current density is 2-4A / dm 2 Electroplating for 30-35 minutes, current density is 1-2A / dm 2electroplating for 5-8 min, wherein the electroplating solution comprises 180-200 g / L copper sulfate, 40-50 g / L sulfuric acid, 55-65 g / L sodium sulfate, 1-2 g / L sodium chloride, 0.1-0.3 g / L 2-mercaptobenzimidazole, 0.1-0.3 g / L ethylenethiourea, 5-10 g / L sodium polydithiobisphenyl sulfone, 10-15 g / L polyethylene glycol, 0.01-0.05 g / L alkyl imidazoline quaternary ammonium salt, 0.01-0.05 g / L diethanolamine, and 0.05-0.1 g / L bipyridine; S5, the specific steps of the copper-plated wire being stretched and annealed several times: After the copper-plated wire is drawn at room temperature, it is annealed at 400-450℃ for 3-4 hours, then drawn at room temperature again, and annealed at 450-550℃ for 3-4 hours. Example 2

[0021] A preparation method of a copper-coated aluminum wire for a photovoltaic welding strip bus bar, the preparation method comprising: S1, alkali washing: the coiled aluminum wire is unwound by a wire unwinder, and the aluminum wire is soaked in an alkali washing solution in an alkali washing tank for 45 s, and the alkali washing solution is a 45 g / L sodium hydroxide solution, and then the aluminum wire is moved to a water washing tank for water washing; S2, fluoride-free acid washing: the alkali-washed aluminum wire is soaked in a fluoride-free acid washing solution and ultrasonically assisted for acid washing, water washing, and neutralization to obtain a fluoride-free acid-washed aluminum wire, and the specific steps are as follows: S21, the alkali-washed aluminum wire is soaked in a fluoride-free acid washing solution for 80 s, wherein the fluoride-free acid washing solution comprises 187 g / L phosphoric acid, 92 g / L sulfuric acid, 60 g / L sodium vinyl sulfonate, 13.6 g / L alkyl imidazoline quaternary ammonium salt, 10.5 g / L diethanolamine, 16.7 g / L hydrogen peroxide, 13.5 g / L potassium persulfate, 45.2 g / L sodium nitrate, 2.1 g / L sodium dodecyl benzene sulfonate, and 7.25 g / L carboxymethyl cellulose; S22, the fluoride-free acid-washed aluminum wire is subjected to hot water washing and cold water washing; S23, the water-washed aluminum wire is soaked in 1% sodium carbonate for 30 s to obtain a fluoride-free acid-washed aluminum wire; S3, anodic oxidation: the fluoride-free acid-washed aluminum wire is anodically oxidized in a phosphoric acid solution at a current density of 1 A / dm 2 , and a temperature of 25℃ for 13 min, and the anodically oxidized wire is subjected to water washing, wherein the phosphoric acid solution comprises 350 g / L phosphoric acid, 1 g / L sulfuric acid, 1 g / L sodium dodecyl sulfate, and 1 g / L oxalic acid; S4, copper plating: the wire is placed in an electroplating solution for copper plating, the electroplating solution comprising 180 g / L copper sulfate, 45 g / L sulfuric acid, 60 g / L sodium sulfate, 1.6 g / L sodium chloride, 0.2 g / L 2-mercaptobenzimidazole, 0.2 g / L ethylenethiourea, 6 g / L sodium polydithiobisphenyl sulfone, 12 g / L polyethylene glycol (molecular weight 6000), 0.01 g / L alkyl imidazoline quaternary ammonium salt, 0.01 g / L diethanolamine, 0.05 g / L bipyridine, the temperature of electroplating being 37℃, the current density being 2A / dm 2 The down electroplating time is 1min; copper sulfate and hydrogen peroxide are added to the electroplating solution, and the temperature of electroplating is adjusted to 55℃, the current density being 4A / dm 2 The down electroplating time is 25min, and the current density is 1A / dm 2 The down electroplating time is 8min; S5, the specific steps of stretching and annealing the copper-plated wire several times: The copper-plated wire is drawn at room temperature, then annealed at 400℃ for 4 hours, drawn at room temperature again, and then annealed at 550℃ for 4 hours. Example 3

[0022] A preparation method of a copper-clad aluminum wire, the preparation method comprising: S1, alkali washing: the coiled aluminum wire is unwound by a wire unwinder, and then soaked in an alkali washing solution in an alkali washing tank for 45s, the alkali washing solution being a 45g / L sodium hydroxide solution, and then moved to a water washing tank for water washing; S2, fluoride-free acid washing: the alkali-washed aluminum wire is soaked in a fluoride-free acid washing solution and ultrasonically assisted for acid washing, water washing, and neutralization, to obtain a fluoride-free acid-washed aluminum wire, the specific steps being: S21, the alkali-washed aluminum wire is soaked in a fluoride-free acid washing solution for 75s, wherein the fluoride-free acid washing solution comprises 187 g / L phosphoric acid, 92 g / L sulfuric acid, 60 g / L sodium vinyl sulfonate, 13.6 g / L alkyl imidazoline quaternary ammonium salt, 10.5 g / L diethanolamine, 16.7 g / L hydrogen peroxide, 13.5 g / L potassium persulfate, 45.2 g / L sodium nitrate, 2.1 g / L sodium dodecylbenzenesulfonate, and 7.25 g / L carboxymethyl cellulose; S22, the fluoride-free acid-washed aluminum wire is subjected to hot water washing and cold water washing; S23, the water-washed aluminum wire is soaked in 1% sodium carbonate for 25s, to obtain a fluoride-free acid-washed aluminum wire; S3, anodic oxidation: the fluoride-free acid-washed aluminum wire is placed in a phosphoric acid solution, the temperature of the solution being 20℃, and the current density being 1A / dm 2anodizing for 15 min at a temperature of 25℃, and then washing the anodized wire with water, wherein the phosphoric acid solution comprises 360 g / L of phosphoric acid, 1 g / L of sulfuric acid, 1 g / L of sodium dodecyl sulfate, and 1 g / L of oxalic acid; S4, copper plating: the wire is placed in a plating solution to be plated with copper, wherein the plating solution comprises 180 g / L of copper sulfate, 45 g / L of sulfuric acid, 60 g / L of sodium sulfate, 1.649 g / L of sodium chloride, 0.2 g / L of 2-mercaptobenzimidazole, 0.2 g / L of ethylenethiourea, 6 g / L of sodium polydithiobisbenzenesulfonate, 12 g / L of polyethylene glycol (molecular weight of 6000), 0.01 g / L of alkylimidazoline quaternary ammonium salt, 0.01 g / L of diethanolamine, and 0.05 g / L of bipyridine, and the plating temperature is 35℃, the plating current density is 2 A / dm 2 The plating temperature is adjusted to 55℃ by adding copper sulfate and hydrogen peroxide to the plating solution, and the plating current density is 4 A / dm 2 The plating time is 25 min, and the plating current density is 1 A / dm 2 The plating time is 2 min. S5, the copper-plated wire is subjected to a plurality of stretching and annealing processes, and the specific steps are as follows: The copper-plated wire is subjected to normal-temperature drawing, 430℃ annealing for 4 hours, normal-temperature drawing, and 490℃ annealing for 4 hours. The wire produced in Example 1-3 is detected according to the standard GB / T 31985-2015, and the detection results are shown in Table 1.

[0023] Table 1: Performance test table of wires produced in different examples

[0024] Comparative Example 1 The same as Example 3, except that zinc plating is used instead of anodizing.

[0025] S31, first zinc immersion: the aluminum wire is transported into a solution in a first zinc immersion tank to be immersed in zinc, and then moved to a water washing tank to be washed with water; The solution for the first zinc immersion comprises 600 g / L of sodium hydroxide, 78 g / L of zinc oxide, and the rest is water, the solution temperature for the zinc immersion is 38℃, and the zinc immersion time is 1 min.

[0026] S32, first zinc removal: the zinc-immersed and washed aluminum wire is placed in a solution in an acid washing tank to remove zinc, and then moved to a water washing tank to be washed with water; S33, the solution for the first zinc removal comprises nitric acid and water, the mass concentration of the nitric acid is 30%, the zinc removal temperature is 35℃, and the zinc removal time is 45 s.

[0027] S34, second zinc dipping: the aluminum wire is dipped into the solution of the second zinc dipping tank, and then moved to the water washing tank for water washing; the solution for zinc dipping includes 250 g / L of sodium hydroxide, 45 g / L of zinc oxide, and the rest is water, the temperature of the solution for zinc dipping is 38℃, and the time for zinc dipping is 1 min.

[0028] Comparative Example 2 The same as Comparative Example 2, except that the no-fluorine acid washing is different.

[0029] Specific steps of the aluminum wire after no-fluorine acid washing: S21, the aluminum wire after the alkali washing is soaked in a no-fluorine acid washing solution for 5 s, wherein the no-fluorine acid washing solution includes 187 g / L of phosphoric acid, 92 g / L of sulfuric acid, 60 g / L of sodium vinyl sulfonate, 16.7 g / L of hydrogen peroxide, 13.5 g / L of potassium persulfate, 45.2 g / L of sodium nitrate, and 2.1 g / L of sodium dodecyl benzene sulfonate; S22, the aluminum wire after the no-fluorine acid washing is subjected to hot water washing and cold water washing; S23, the aluminum wire after the water washing is soaked in 1% sodium carbonate for 25 s to obtain the aluminum wire after the no-fluorine acid washing.

[0030] Comparative Example 3 The same as Comparative Example 2, except that the no-fluorine acid washing is different.

[0031] Specific steps of the aluminum wire after no-fluorine acid washing: S21, the aluminum wire after the alkali washing is soaked in a no-fluorine acid washing solution for 75 s, wherein the no-fluorine acid washing solution includes 280 g / L of sulfuric acid, 16.7 g / L of hydrogen peroxide, 13.5 g / L of potassium persulfate, and 45.2 g / L of sodium nitrate; S22, the aluminum wire after the no-fluorine acid washing is subjected to hot water washing and cold water washing; S23, the aluminum wire after the water washing is soaked in 1% sodium carbonate for 25 s to obtain the aluminum wire after the no-fluorine acid washing.

[0032] Comparative Example 4 A no-fluorine acid aluminum wire, the no-fluorine acid washing solution is different.

[0033] S1, alkali washing: the coiled aluminum wire is unwound by an unwinding machine, and the aluminum wire is soaked in an alkali washing solution in an alkali washing tank for alkali washing for 45 s, the alkali washing solution is a 45 g / L sodium hydroxide solution, and then the aluminum wire is moved to a water washing tank for water washing; S2, no-fluorine acid washing: the aluminum wire after the alkali washing is soaked in a no-fluorine acid washing solution combined with ultrasonic assisted acid washing, water washing, and neutralization to obtain the aluminum wire after the no-fluorine acid washing. S21, immersing the aluminum wire after the alkali cleaning in a fluoride-free acid cleaning solution for 75s, wherein the fluoride-free acid cleaning solution comprises 187 g / L phosphoric acid, 92 g / L sulfuric acid, 60 g / L sodium vinyl sulfonate, 13.6 g / L benzotriazole, 16.7 g / L hydrogen peroxide, 13.5 g / L potassium persulfate, 45.2 g / L sodium nitrate, 2.1 g / L sodium dodecyl benzene sulfonate, and 7.25 g / L carboxymethyl cellulose; S22, hot water cleaning and cold water cleaning of the aluminum wire after the fluoride-free acid cleaning; S23, immersing the aluminum wire after the water cleaning in 1% sodium carbonate for 25s to obtain the aluminum wire after the fluoride-free acid cleaning.

[0034] The oxide film removal of the aluminum wire after the fluoride-free acid cleaning of Comparative Example 2-4 was detected by the four-probe detection method, as shown in Table 2 below.

[0035] Table 2 Oxide film removal of the aluminum wire after the fluoride-free acid cleaning

[0036] Comparative Example 5 The same as Example 3, except that the plating solution for copper plating is different.

[0037] The plating solution comprises 165 g / L copper sulfate, 45 g / L sulfuric acid, 7 g / L phytic acid, 0.2 g / L ethylene thiourea, 6 g / L sodium polydithiobisbenzenesulfonate, 12 g / L polyethylene glycol (molecular weight 6000), 0.01 g / L benzotriazole, 0.15 g / L 2-mercaptobenzothiazole, and 0.05 g / L bipyridine.

[0038] Comparative Example 6 The same as Example 3, except that S4 and S5 are different.

[0039] S4, copper plating: immersing the wire in a plating solution comprising 165 g / L copper sulfate, 45 g / L sulfuric acid, 0.2 g / L ethylene thiourea, 12 g / L polyethylene glycol (molecular weight 6000), 0.01 g / L alkyl imidazoline quaternary ammonium salt, 0.01 g / L diethanolamine, 0.15 g / L 2-mercaptobenzothiazole, and 0.05 g / L bipyridine to perform copper plating, the temperature of the plating is 37℃, and the plating time is 1 min at a current density of 2 A / dm 2 The temperature of the plating is 55℃, and the plating time is 25 min at a current density of 4 A / dm 2 The temperature of the plating is 55℃, and the plating time is 25 min at a current density of 4 A / dm 2 The plating time is 2 min at a current density of 1 A / dm S5, drying.

[0040] The non-fluoride pickling aluminum wire of Comparative Example 2-4 was anodized, plated with copper and stretch annealed according to the preparation method of Example 3, and the wire produced according to Comparative Example 1-6 was tested according to the standard GB / T 31985-2015, and the test results are shown in Table 3 below.

[0041] Table 3 Performance test table of different example wires

[0042] The thermal expansion coefficients of the copper-clad aluminum wires of Comparative Example 1-6 and Example 3 at 593℃ were tested respectively.

[0043] Table 4 Thermal expansion coefficients of different wires

[0044] The present application can be implemented in various different ways and is not limited to the described embodiments, and it will be understood by those skilled in the art that the present application can be implemented by other specific ways without changing the technical idea or essential characteristics of the present application. Therefore, it should be understood that the above-described embodiments are exemplary and are not intended to limit the present application.

Claims

1. A method for preparing copper-clad aluminum wire for photovoltaic welding ribbon busbar, characterized in that: include: S1, alkali washing: immersing the aluminum wire in an alkali washing solution for alkali washing, and then washing with water to obtain an alkali-washed aluminum wire; S2, fluorine-free pickling: immersing the alkali-washed aluminum wire in a fluorine-free pickling solution, washing with water, and neutralizing to obtain a fluorine-free pickling aluminum wire; S3, anodizing: anodizing the aluminum wire after the fluorine-free acid washing in a phosphoric acid solution, and washing with water to obtain a wire; S4, copper plating: Place the wire in the electroplating solution for copper plating. The electroplating temperature is 25-30℃ and the current density is 1-2A / dm 2 The electroplating time is 5-8min; copper sulfate and hydrogen peroxide are added to the electroplating solution, the electroplating temperature is adjusted to 40-55℃, and the current density is 2-4A / dm 2 Electroplating for 30-35 minutes, current density is 1-2A / dm 2 Electroplating for 5-8 minutes, wherein the electroplating solution includes 180-200 g / L copper sulfate, 40-50 g / L sulfuric acid, 55-65 g / L sodium sulfate, 1-2 g / L sodium chloride, 0.1-0.3 g / L 2-mercaptobenzoimidazole, 0.1-0.3 g / L ethylene thiourea, 5-10 g / L sodium polydisulfide, and 10-15 g / L polyethylene glycol; S5, performing several stretching and annealing treatments on the copper-plated wire to obtain a copper-clad aluminum wire.

2. Preparation of the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 1 S1, alkali washing: immersing the aluminum wire in an alkali washing solution for alkali washing, and then washing with water to obtain the alkali-washed aluminum wire; S2, fluorine-free pickling: immersing the alkali-washed aluminum wire in a fluorine-free pickling solution, washing with water, and neutralizing to obtain a fluorine-free pickling aluminum wire; S3, anodizing: anodizing the aluminum wire after the fluorine-free acid washing in a phosphoric acid solution, and washing with water to obtain a wire; S4, copper plating: Place the wire in the electroplating solution for copper plating. The electroplating temperature is 25-30℃ and the current density is 1-2A / dm 2 The electroplating time is 5-8min; copper sulfate and hydrogen peroxide are added to the electroplating solution, the electroplating temperature is adjusted to 40-55℃, and the current density is 2-4A / dm 2 Electroplating for 30-35 minutes, current density is 1-2A / dm 2 Electroplating for 5-8 minutes, The electroplating solution comprises 180-200 g / L copper sulfate, 40-50 g / L sulfuric acid, 55-65 g / L sodium sulfate, 1-2 g / L sodium chloride, 0.1-0.3 g / L 2-mercaptobenzoimidazole, 0.1-0.3 g / L ethylenethiourea, 5-10 g / L sodium polydisulfide, 10-15 g / L polyethylene glycol, 0.01-0.05 g / L alkyl imidazoline quaternary ammonium salt, 0.01-0.05 g / L diethanolamine, and 0.05-0.1 g / L bipyridine; S5, a method for obtaining a copper-clad aluminum wire by subjecting the copper-plated wire to several stretching and annealing treatments, characterized in that in the fluorine-free pickling step, the alkali-washed aluminum wire is immersed in a fluorine-free pickling solution, washed with water, and neutralized to obtain the fluorine-free pickled aluminum wire in the following steps: S21, soaking the alkali-washed aluminum wire in a fluorine-free acid cleaning solution for 70-80 seconds; S22, washing the aluminum wire after the fluorine-free acid washing with hot water and cold water; S23, soaking the washed aluminum wire in a neutralizing solution for 25-30 seconds to obtain a fluorine-free acid-washed aluminum wire.

3. The method for preparing the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 2, wherein: The fluorine-free acid cleaning solution comprises 180-190 g / L phosphoric acid, 90-100 g / L sulfuric acid, 55-65 g / L sodium vinyl sulfonate, 10-15 g / L alkyl imidazoline quaternary ammonium salt, 10-15 g / L diethanolamine, 15-20 g / L hydrogen peroxide, 10-15 g / L potassium persulfate, 40-50 g / L sodium nitrate, 1-3 g / L sodium dodecylbenzene sulfonate and 5-10 g / L carboxymethyl cellulose.

4. The method for preparing the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 3, wherein: The neutralizing solution is 0.5-1% sodium carbonate or 0.5-1% ammonia water.

5. The method for preparing the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 1, wherein: In the step of anodizing, the anodizing treatment condition is a current density of 1-2 A / dm 2 , Anodic oxidation at 25°C for 10-15 minutes.

6. The method for preparing the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 5, characterized in that: In the step of anodizing, the phosphoric acid solution comprises 300-420 g / L phosphoric acid, 1-2 g / L sulfuric acid, 1-2 g / L sodium lauryl sulfate and 1-2 g / L oxalic acid.

7. The method for preparing the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 1, wherein: The alkaline washing solution is a 40-50g / L sodium hydroxide solution.

8. The method for preparing the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 1, wherein: The phosphoric acid solution comprises: 300-420 g / L phosphoric acid, 1-2 g / L sulfuric acid, 1-2 g / L sodium lauryl sulfate and 1-2 g / L oxalic acid.

9. The method for preparing the copper-clad aluminum wire for photovoltaic welding ribbon busbar according to claim 1, wherein: The step of subjecting the copper-plated wire to several stretching and annealing treatments to obtain the copper-clad aluminum wire is as follows: The copper-plated wire is drawn at room temperature and then annealed at 400-450°C for 3-4 hours. After being drawn at room temperature, it is annealed at 450-550°C for 3-4 hours.

10. The copper-clad aluminum wire for photovoltaic welding ribbon busbars is prepared by the preparation method according to claims 1-9, characterized in that: The copper content is 40-50%.

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