Production method of CIC photovoltaic welding strip copper-coated chilean material

Abstract

This invention provides a method for producing copper-clad Invar material for CIC photovoltaic welding ribbons, relating to the field of photovoltaic material preparation technology. The method includes the following steps: taking a modified Invar alloy rod, grinding its surface to obtain a core material; the modified Invar alloy is obtained by adding vanadium to Invar alloy melt for molten alloying, and then casting it into an ingot; taking an oxygen-free copper round tube, grinding its inner wall, and inserting the core material into the oxygen-free copper round tube in an atmosphere furnace via interference fitting to obtain an alloy insert; cold-rolling the alloy insert, annealing, to obtain a cold-rolled rod. The core material is coated with a copper layer, which ensures compatibility with ceramic / glass sealing and, due to its easy formation of a dense oxide film, provides good resistance to damp heat and is easy to solder. Pure copper itself has limited bending and fatigue resistance, but when combined with Invar core material, the overall mechanical properties and welding effect of the material are significantly better than pure copper, significantly improving the overall process compatibility and long-term reliability.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic material preparation technology, specifically to a method for producing CIC photovoltaic solder strip copper-clad invar material. Background Technology

[0002] As photovoltaic modules develop towards higher power and higher efficiency, higher requirements are placed on the conductivity, mechanical properties, and interface compatibility with solar cells of photovoltaic ribbons. Traditional photovoltaic ribbons generally use high-purity oxygen-free copper as their substrate. Copper primarily functions as a conductor in the ribbon, and to achieve good conductivity and mechanical load-bearing capacity, the substrate is typically high-purity oxygen-free copper with a purity of up to 99.95% and an oxygen content of no more than 0.003%. However, pure copper-based ribbons suffer from problems such as dimensional thermal drift, insufficient fatigue resistance, and insufficient creep resistance under high and low temperature cycling conditions.

[0003] To balance conductivity, lightweight design, and cost reduction, the industry has explored using composite structures to replace pure copper substrates. For example, a composite structure of "aluminum layer + copper layer" is used as the solder strip substrate, with conductivity and mechanical properties ensured by limiting the copper-aluminum mass ratio and copper layer thickness. Another example is copper-clad aluminum solder strips, which enhance tensile strength and fatigue resistance while maintaining lightweight design, allowing for better resistance to temperature differences, mechanical stress, and external tensile forces. However, the thermal expansion problem of the substrate itself remains unresolved in these solutions, and dimensional drift of the substrate under high and low temperature cycling still affects the long-term reliability of the solder strip and the cell / packaging interface. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for producing copper-clad invar material for CIC photovoltaic welding strips. This invention is achieved through the following technical solution: A method for producing CIC photovoltaic welding strip copper-clad invar material includes the following steps: S1. Take the modified Invar alloy rod, polish the surface to obtain the core material; The modified Invar alloy is obtained by adding vanadium to the Invar alloy melt for melt alloying, and then casting it into ingots; S2. Take an oxygen-free copper round tube, grind the inner wall, and insert the core material into the oxygen-free copper round tube in an atmosphere furnace to obtain an alloy embedded tube. S3, cold-rolled alloy insert, annealed, to obtain cold-rolled bar; S4. The cold-rolled bar is drawn into shape and wound to obtain the welding strip.

[0005] Preferably, the modified Invar alloy described in step S1 consists of the following components by mass fraction: C 0.013-0.110%, Si 0.16-0.17%, Mn 0.25-0.31%, S 0.001-0.002%, Ni 36.01-36.21%, V 0.22-0.49%, balance Fe; The mass ratio of Mn to V is <1.2.

[0006] Preferably, the specific preparation steps of the modified Invar alloy rod are as follows: (1) Smelt each component under argon protection and hold at 1100-1200℃ for 1-1.5h, then forge it into a slab; (2) The slab is kept at 1200-1250℃ for 1-2 hours, hot rolled into a rod, and air-cooled to room temperature to obtain modified Invar alloy rod.

[0007] Preferably, the sanding in steps S1 and S2 is done using 400-600 grit sandpaper.

[0008] Preferably, in step S2, argon gas is introduced into the atmosphere furnace and the temperature is maintained at 850-950°C.

[0009] Preferably, in step S3, the cold rolling process involves 8-12 passes to produce a sheet with a final thickness of 0.5 mm, with a deformation of 15-25% per pass, followed by one annealing process, specifically held at 600-800°C for 10-20 minutes in a nitrogen atmosphere.

[0010] This invention provides a method for producing copper-clad invar material for CIC photovoltaic welding strips, which has the following advantages compared with the prior art: This composite solder strip uses modified Invar alloy as its core material. Modified Invar alloy has an extremely low coefficient of thermal expansion, meaning it hardly expands or contracts with temperature, providing an overall very low coefficient of thermal expansion and effectively preventing the drift caused by dimensional changes in pure copper under high and low temperature cycling. The core material is covered with a copper layer, which ensures compatibility with ceramic / glass sealing and, due to its ability to easily form a dense oxide film, provides excellent resistance to damp heat and facilitates soldering. While pure copper itself has limited bending and fatigue resistance, the composite with Invar core material significantly improves the overall mechanical properties and welding performance compared to pure copper, resulting in significantly enhanced overall process compatibility and long-term reliability. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] Unless otherwise specified, all reagents used in the following schemes are commercially available products.

[0013] Preparation of modified Invar alloy: The modified Invar alloy consists of the components listed in Table 1 by mass fraction, with the balance being Fe.

[0014] Table 1 The specific preparation steps for the modified Invar alloy rod are as follows: S1. The components are smelted under argon protection and held at 1150℃ for 1.2h, and then forged into slabs. S2. The slab is held at 1230℃ for 1.5 hours, hot-rolled into a rod shape, and air-cooled to room temperature to obtain a modified Invar alloy rod.

[0015] Example 1: A method for producing copper-clad invar material for CIC photovoltaic welding strips: S1. Take a 6mm diameter rod made of modified Invar alloy A, and polish the surface with 500-grit sandpaper to obtain the core material. S2. Take an oxygen-free copper round tube with an outer diameter of 10mm, polish the inner wall of the tube with 600-grit sandpaper, introduce argon gas into the atmosphere furnace and maintain the temperature at 850℃, and insert the core material into the oxygen-free copper round tube with interference fit (interference = 0.2mm) to obtain the alloy insert tube. S3. The prepared alloy insert is fed into the cold rolling mill and cold rolled into a plate with a final thickness of 0.5 mm through 10 passes. The deformation per pass of cold rolling is 25%. The plate is annealed once in the middle (held at 800℃ for 15 min in nitrogen atmosphere) to obtain a cold-rolled bar. S4. The cold-rolled bar is drawn into shape and wound to obtain the welding strip.

[0016] Example 2: A method for producing copper-clad invar material for CIC photovoltaic welding strips: S1. Take a 6mm diameter rod made of modified Invar alloy A, and polish the surface with 500-grit sandpaper to obtain the core material. S2. Take an oxygen-free copper round tube with an outer diameter of 10mm, polish the inner wall of the tube with 400-grit sandpaper, introduce argon gas into the atmosphere furnace and maintain the temperature at 950℃, and insert the core material into the oxygen-free copper round tube with interference fit (interference = 0.2mm) to obtain the alloy insert tube. S3. The prepared alloy insert is fed into the cold rolling mill and cold rolled into a plate with a final thickness of 0.5 mm through 10 passes. The deformation per pass of cold rolling is 15%, and it is annealed once in the middle (held at 600℃ for 15 min in nitrogen atmosphere) to obtain a cold-rolled bar. S4. The cold-rolled bar is drawn into shape and wound to obtain the welding strip.

[0017] Comparative Example 1: This comparative example follows the production method of Example 1, but without adding modified Invar alloy A, and only uses oxygen-free copper to prepare photovoltaic welding wire.

[0018] Comparative Example 2: This comparative example follows the production method of Example 1, except that the material used to prepare the bar is replaced with modified Invar alloy B.

[0019] Comparative Example 3: This comparative example follows the production method of Example 1, except that the material used to prepare the bar is replaced with modified Invar alloy C.

[0020] Comparative Example 4: This comparative example follows the production method of Example 1, except that the material used to prepare the bar is replaced with modified Invar alloy D.

[0021] Detection: Test methods (all examples / comparative examples use the following uniform standard): 1. Tensile strength: GB / T228.1-2021, electronic universal testing machine (Instron5967), gauge length 50mm, speed 5mm / min.

[0022] 2. Weld joint shear force: IEC62757-1, shearing speed 10mm / min, average value of 10 weld joints tested.

[0023] 3. Retention rate of resistance to damp heat aging: IEC61215-2021, tensile strength retention rate after 2000h at 85℃ / 85%RH.

[0024] 4. Interface porosity: X-ray micro-CT (Zeiss Xradia 510), percentage of 3D reconstructed volume.

[0025] The results are shown in Table 2 below: Table 2 Observing the data in Table 2 above, it can be seen that the experimental data of Example 1 are the best. The combination of oxygen-free copper and modified Invar alloy A in Example 1 significantly improves the overall mechanical properties and welding effect of the material. This statement is supported by the experimental data of Comparative Example 1. Comparative Example 2, which did not add vanadium to the Invar alloy, has weaker mechanical properties and welding effect than Example 1, and its weld shear force is relatively smaller than other comparative examples. In Comparative Examples 3-4, the Mn to V mass ratio is 1.2 and >1.2, unlike the Mn to V mass ratio <1.2 in Example 1. Although the tensile strength of Comparative Example 3 is improved, it is not higher than that of Example 1. The weld shear force in Comparative Example 4 is higher than that in Comparative Example 3, but it is still lower than that in Example 1.

[0026] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing copper-clad inductor material for CIC photovoltaic welding strips, characterized in that, The production method includes the following steps: S1. Take the modified Invar alloy rod, polish the surface to obtain the core material; The modified Invar alloy is obtained by adding vanadium to the Invar alloy melt for melt alloying, and then casting it into ingots; S2. Take an oxygen-free copper round tube, grind the inner wall, and insert the core material into the oxygen-free copper round tube in an atmosphere furnace to obtain an alloy embedded tube. S3, cold-rolled alloy insert, annealed, to obtain cold-rolled bar; S4. The cold-rolled bar is drawn into shape and wound to obtain the welding strip.

2. The production method according to claim 1, characterized in that, The modified Invar alloy described in step S1 consists of the following components by mass fraction: C 0.013-0.110%, Si 0.16-0.17%, Mn 0.25-0.31%, S 0.001-0.002%, Ni 36.01-36.21%, V 0.22-0.49%, balance Fe; The mass ratio of Mn to V is <1.

2.

3. The production method according to claim 2, characterized in that, The specific preparation steps of the modified Invar alloy rod are as follows: (1) Smelt each component under argon protection and hold at 1100-1200℃ for 1-1.5h, then forge it into a slab; (2) The slab is kept at 1200-1250℃ for 1-2 hours, hot rolled into a rod, and air-cooled to room temperature to obtain modified Invar alloy rod.

4. The production method according to claim 1, characterized in that, The modified Invar alloy rod described in step S1 has a diameter of 6 mm.

5. The production method according to claim 1, characterized in that, The oxygen-free copper round tube mentioned in steps S1 and S2 has an outer diameter of 10mm and an interference fit of ≥0.2mm.

6. The production method according to claim 1, characterized in that, The sanding described in steps S1 and S2 uses 400-600 grit sandpaper.

7. The production method according to claim 1, characterized in that, Argon gas is introduced into the atmosphere furnace in step S2 and the temperature is maintained at 850-950°C.

8. The production method according to claim 1, characterized in that, In step S3, the cold rolling process is carried out in 8-12 passes to produce a sheet with a final thickness of 0.5 mm, with a deformation of 15-25% per pass. The sheet is then annealed once, specifically in a nitrogen atmosphere at 600-800℃ for 10-20 minutes.

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