Busbar, method for manufacturing the same, and photovoltaic module

Abstract

The application discloses a busbar, a preparation method thereof and a photovoltaic module. The preparation method of the busbar comprises the following steps: providing a copper base material, the copper base material is in a strip shape, and the copper base material has oppositely arranged welding surfaces and non-welding surfaces; uniformly applying a flux to the welding surfaces and the non-welding surfaces of the copper base material; passing the copper base material coated with the flux through a tin tank containing liquid tin, so as to cover the welding surfaces and the non-welding surfaces of the copper base material with tin liquid; blowing off the tin liquid adhered to the welding surfaces and the non-welding surfaces of the copper base material by using an air knife, and controlling the air pressure of the air knife, so that the thickness of the tin layer of the non-welding surfaces is smaller than the thickness of the tin layer of the welding surfaces; and cooling the tin layer on the copper base material to solidify, so as to obtain a busbar with thinned non-welding surfaces. The preparation method of the busbar can reduce the thickness of the tin layer of the non-welding surfaces of the busbar and reduce the production cost of the busbar.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic technology, specifically relating to a busbar, its preparation method, and a photovoltaic module. Background Technology

[0002] In photovoltaic systems, busbars are key components used to connect multiple solar cells in series or parallel. Busbars are typically made of highly conductive materials such as copper or aluminum, and are designed with one surface for soldering to connect the solar cells, while the other surface is not involved in soldering. The surface used for soldering to connect the solar cells is called the solder face; the other surface is called the non-solder face. The solder face is used to connect to the solder strips on the solar cells, and because soldering is required, the tin layer thickness on the solder face must be sufficient. The non-solder face has no other function, and to reduce costs, the amount of tin used on the non-solder face can be reduced while meeting quality requirements. However, existing busbars have equal thickness on both sides, and it is difficult to reduce or control the tin layer thickness on the non-solder face during manufacturing, leading to copper leakage and affecting the busbar's performance.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a busbar that can reduce the thickness of the tin layer on the non-soldering surface of the busbar and reduce the production cost of the busbar.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: a method for preparing a busbar, comprising: providing a copper substrate, the copper substrate being strip-shaped and having a welding surface and a non-welding surface disposed opposite to each other; uniformly coating the welding surface and the non-welding surface of the copper substrate with flux; passing the copper substrate coated with flux through a tin bath containing liquid tin, covering the welding surface and the non-welding surface of the copper substrate with molten tin; using an air knife to blow away the molten tin adhering to the welding surface and the non-welding surface of the copper substrate, controlling the air knife pressure so that the tin layer thickness on the non-welding surface is less than the tin layer thickness on the welding surface; cooling until the tin layer on the copper substrate solidifies, obtaining a busbar with single-sided thinning.

[0006] In one or more embodiments of the present invention, the method for preparing the copper substrate includes: continuously extracting solid copper wire from molten copper; rolling the solid copper wire using a cold rolling process to obtain copper wire; rolling the copper wire to obtain a strip-shaped copper substrate; and annealing the rolled copper substrate.

[0007] In one or more embodiments of the present invention, the annealing process includes: heating the rolled copper substrate to 550°C-750°C; and feeding the heated copper substrate into a cooling water tank at 15°C-25°C at a speed of 90m / min-140m / min for cooling.

[0008] In one or more embodiments of the present invention, air knives are provided on both the welding surface and the non-welding surface of the copper substrate, and the air pressure of the air knife provided on the welding surface is less than that of the air knife provided on the non-welding surface.

[0009] In one or more embodiments of the present invention, the air pressure of the air knife is less than or equal to 150 kPa, and the air pressure of the air knife on the welded surface is 5 kPa-10 kPa lower than that on the non-welded surface.

[0010] In one or more embodiments of the present invention, the angle between the air outlet direction of the air knife and the welded and non-welded surfaces of the copper substrate is 55°-60°.

[0011] In one or more embodiments of the present invention, the tin layer thickness of the non-soldering surface is 5μm-12μm; the tin layer thickness of the soldering surface is greater than 15μm.

[0012] In one or more embodiments of the present invention, the copper substrate has a width of 4mm-8mm and a thickness of 0.2mm-0.4mm.

[0013] Compared with existing technologies, the busbar manufacturing method of the present invention achieves simultaneous control of the tin layer thickness on both the non-soldering and soldering surfaces using an air knife. Furthermore, by controlling the angle and pressure of the air knife, the thickness of the tin layer on the non-soldering surface is reduced while maintaining a constant tin layer thickness on the soldering surface. This achieves both the functionality of the soldering surface and reduces the production cost of the busbar. Additionally, this process prevents the tin layer on the non-soldering surface from becoming too thin and exposing the copper substrate, thus ensuring the relevant performance of the busbar.

[0014] Another specific embodiment of the present invention provides the following technical solution: a busbar, which is prepared by the above-described busbar preparation method.

[0015] Compared with the prior art, the tin layer thickness of the non-soldering surface of the busbar of the present invention is reduced, while the tin layer thickness of the soldering surface remains unchanged, thereby reducing the overall production cost while taking into account the performance of the busbar.

[0016] Another specific embodiment of the present invention provides the following technical solution: a photovoltaic module, which includes a photovoltaic cell and the above-mentioned busbar, wherein the busbar is connected to the photovoltaic cell.

[0017] Compared with the prior art, the photovoltaic module of the present invention uses busbars to connect photovoltaic cells, which can reduce production costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a method for preparing a busbar in one embodiment of the present invention;

[0020] Figure 2 This is a flowchart of step S1 in the method for preparing a busbar according to an embodiment of the present invention;

[0021] Figure 3 This is a flowchart of step S14 in the method for preparing a busbar in one embodiment of the present invention;

[0022] Figure 4 This is a SEM image of the busbar in Embodiment 1 of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0024] like Figure 1 As shown, a method for preparing a busbar in one embodiment of the present invention includes steps S1-S5.

[0025] Step S1: Provide a copper substrate, which is strip-shaped and has a welded surface and a non-welded surface arranged opposite each other.

[0026] Specifically, in step S1, a strip-shaped copper substrate with a width of 4mm-8mm and a thickness of 0.2mm-0.4mm is provided, having oppositely arranged welding and non-welding surfaces. Understandably, the strip-shaped copper substrate also has four edge surfaces, but due to its thinness, these are not limited or described here.

[0027] Furthermore, to ensure the quality of the copper substrate and the relevant performance of the busbar, such as Figure 2As shown, the method for preparing the copper substrate includes steps S11-S14.

[0028] Step S11: Continuously extract solid copper wires from the molten copper liquid.

[0029] Specifically, in step S11, solid copper wire is slowly and continuously extracted from the molten copper liquid by utilizing the mechanism of cooling and crystallization of molten metal.

[0030] Metal molten metal cooling and crystallization refers to the process during the smelting of metallic materials, where atoms lose their ordered structure due to high temperatures and enter a liquid state. In this liquid state, metal atoms move randomly. The thermal motion of these atoms at high temperatures causes the liquid to melt and mix, and the various substances involved in the melting process are influenced by attraction, resulting in a series of stable liquid structures. Then, the liquid structure supercools, heat is dissipated, and crystals form from nothing, growing larger until the liquid completely transforms into a solid.

[0031] Step S12: Use cold rolling process to roll solid copper wire to obtain copper wire.

[0032] Specifically, in step S12, since the surface of the solid copper wire extracted in step S11 is irregular, the solid copper wire can be trimmed by cold rolling process to obtain copper wire with a smooth surface and that meets the wire diameter requirements.

[0033] Cold rolling refers to the process of rolling metallic materials at room temperature. Cold rolling gives solid copper wire high precision, high surface quality, and good mechanical properties. Understandably, the cold rolling process may lead to hardening and increased brittleness of the copper wire, but these problems can be mitigated through subsequent steps.

[0034] Step S13: Roll the copper wire to obtain a strip-shaped copper substrate.

[0035] Specifically, in step S13, the copper wire is rolled to obtain a strip-shaped copper substrate having a welded surface and a non-welded surface arranged opposite each other, taking advantage of the ductility of copper.

[0036] Rolling is a processing technique that utilizes the ductility of metals by applying pressure to stretch them into a specific shape. Specifically, it involves extruding and rolling copper wire into copper substrates of a defined shape and size. These copper substrates are used to manufacture busbars and are incorporated into photovoltaic modules; therefore, their width and thickness should not be excessive.

[0037] It is understandable that the length of the copper substrate is determined based on the copper wire and actual usage requirements, and is not limited here.

[0038] Step S14: The rolled copper substrate is treated with an annealing process.

[0039] like Figure 3As shown, specifically, in step S14, the process of treating the rolled copper substrate with electromagnetic heating annealing also includes steps S141-S142.

[0040] Step S141: Heat the rolled copper substrate to 550℃-750℃.

[0041] Step S142: The heated copper substrate is fed into a cooling water tank at a speed of 90m / min-140m / min for cooling at a temperature of 15℃-25℃.

[0042] Since cold rolling and pressing processes alter the properties of copper substrates, annealing is employed to treat the rolled copper substrate. Annealing improves the plasticity and toughness of the copper substrate. Furthermore, it reduces residual stress, stabilizes dimensions, and decreases the tendency for deformation and cracking. Simultaneously, it refines the grain size, adjusts the microstructure of the copper substrate, eliminates structural defects, homogenizes the microstructure and composition of the copper substrate, and improves its material properties, thereby mitigating the problems associated with cold rolling and pressing processes.

[0043] Step S2: Apply flux evenly to the welding and non-welding surfaces of the copper substrate.

[0044] Specifically, in step S2, the copper substrate is passed through a wool felt impregnated with flux so that the welding and non-welding surfaces of the copper substrate can be uniformly coated with flux.

[0045] Applying flux to the copper substrate surface using a felt soaked in flux ensures a uniform coating. This allows for easier and more even tin plating during subsequent tinning, preventing any unplated areas from appearing on the copper substrate.

[0046] Step S3: Pass the copper substrate coated with flux through a tin bath containing liquid tin, so that the soldering and non-soldering surfaces of the copper substrate are covered with molten tin.

[0047] Specifically, in step S3, a copper substrate coated with flux is passed through a tin bath containing liquid tin, so that the soldering and non-soldering surfaces of the copper substrate are covered with molten tin, and then the copper substrate is pulled out of the tin bath.

[0048] In this step, both the non-soldering and soldering surfaces of the copper substrate are plated with liquid tin, and the tin layer thicknesses on the non-soldering and soldering surfaces are similar. However, since the thickness of the non-soldering surface does not need to be the same as that of the soldering surface, it is only necessary to ensure that the copper substrate on the non-soldering surface is not exposed. In addition, when the copper substrate passes through the tin bath containing liquid tin, unevenness in the tin layer on its two surfaces is inevitable, requiring further processing in subsequent steps.

[0049] Step S4: Use an air knife to blow away the molten tin adhering to the soldering and non-soldering surfaces of the copper substrate, and control the air knife pressure so that the tin layer thickness on the non-soldering surface is less than the tin layer thickness on the soldering surface.

[0050] Specifically, in step S4, air knives are installed on both the soldering and non-soldering surfaces of the copper substrate. The air knives on both sides can simultaneously blow air onto the copper substrate, thereby removing unevenly adhered molten solder from both the soldering and non-soldering surfaces. This step utilizes air knives to control the solder layer thickness, thus reducing the thickness of the non-soldering surface of the busbar and saving production costs. Simultaneously, to control the solder layer thickness on the non-soldering surface, the air pressure of the air knife installed on the soldering surface is lower than that of the air knife installed on the non-soldering surface.

[0051] To effectively remove unevenly adhered molten solder, maintain its uniform distribution, and prevent copper substrate exposure, the air knife's air pressure is less than or equal to 150 kPa. Preferably, the air knife pressure on the soldering side is 5-10 kPa lower than that on the non-soldering side. By controlling the air knife pressure on both the soldering and non-soldering sides, the thickness of the solder layer can be effectively controlled, ensuring the solder layer thickness on the soldering side while reducing the thickness of the non-soldering solder layer.

[0052] Furthermore, to ensure efficient removal of molten solder and thickness control, the angle between the air knife's exhaust direction and the soldered and non-soldered surfaces of the copper substrate is 55°-60°. This angle range ensures that the air knife's exhaust will not directly blow the molten solder away from the surface of the copper substrate or expose the copper substrate directly, but rather gradually blow away excess molten solder. It also ensures that the molten solder is always discharged in one direction, making thickness control easier.

[0053] In existing technologies, the solder layer thickness of both the soldered and unsoldered sides of the busbar is greater than 15 μm, and with the addition of the solder layer on the sides of the busbar, the average solder layer thickness is greater than 12 μm. The busbar fabrication method of this invention uses an air knife and controls the air pressure and angle of the air knife to maintain the thickness of the soldered side of the busbar at more than 15 μm, while reducing the thickness of the unsoldered side to 5 μm-12 μm, thereby achieving an average solder layer thickness of greater than 9 μm for the busbar of this invention.

[0054] Step S5: Cool until the tin layer on the copper substrate solidifies to obtain a busbar with thinned sides.

[0055] The present invention will be further described below with reference to specific embodiments.

[0056] Example 1

[0057] A 20m solid copper wire is slowly and continuously extracted from molten copper. The solid copper wire is then cold-rolled to obtain copper wire. The copper wire is then rolled into strips with a width of 6mm and a thickness of 0.3mm. The rolled copper substrate is heated to 600℃ and then fed into a 20℃ cooling water tank at a speed of 100m / min for cooling. Next, the copper substrate is passed through a wool felt impregnated with flux, and flux is evenly coated on the surface of the copper substrate. Then, the copper substrate is passed through a tin bath containing liquid tin, so that the surface of the copper substrate is covered with molten tin, and then the copper substrate is extracted from the tin bath. Air knives are installed on both the welding and non-welding surfaces of the copper substrate. The air knife on the welding side has an air pressure of 130KPa and an air outlet angle of 55° with the welding side; the air knife on the non-welding side has an air pressure of 140KPa and an air outlet angle of 55° with the non-welding side, blowing away the unevenly adhered molten tin on the welding and non-welding surfaces of the copper substrate. Cooling until the tin layer on the copper substrate solidifies results in a busbar that is thinned on one side.

[0058] Figure 4 SEM image of the busbar in Example 1. (e.g.) Figure 4 As shown, the busbar prepared by this method has a tin layer thickness greater than 15 μm on the soldering surface, which meets the soldering requirements. The tin layer thickness on the non-soldering surface is controlled between 5 μm and 12 μm to ensure that the copper substrate on the non-soldering surface is not exposed.

[0059] In summary, the busbar fabrication method of the present invention achieves simultaneous control of the tin layer thickness on both the non-soldering and soldering surfaces using an air knife. Furthermore, by controlling the angle and pressure of the air knife, the thickness of the tin layer on the non-soldering surface is reduced while maintaining a constant tin layer thickness on the soldering surface, thus balancing the functionality of the soldering surface with reduced busbar production costs. Additionally, this fabrication method also prevents the tin layer on the non-soldering surface from becoming too thin and exposing the copper substrate, ensuring the relevant performance of the busbar.

[0060] A busbar in another embodiment of the present invention is prepared using the busbar preparation method described above.

[0061] The tin layer thickness on the non-soldering side of the single-sided thinning is 5μm-12μm; the tin layer thickness on the soldering side is greater than 15μm, and the average tin layer thickness is greater than 9μm.

[0062] In summary, the tin layer thickness on the non-soldering surface of the busbar of the present invention is reduced, while the tin layer thickness on the soldering surface remains unchanged, thereby reducing the overall production cost while taking into account the performance of the busbar.

[0063] A photovoltaic module according to another embodiment of the present invention includes a photovoltaic cell and the aforementioned busbar. The busbar is connected to the photovoltaic cell.

[0064] In summary, the photovoltaic module of the present invention uses busbars to connect photovoltaic cells, which can reduce production costs.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0066] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a busbar, characterized in that, include: A copper substrate is provided, the copper substrate being strip-shaped and having oppositely arranged welding and non-welding surfaces; Flux is evenly applied to both the welding and non-welding surfaces of the copper substrate; The copper substrate coated with flux is passed through a tin bath containing liquid tin, and the soldering and non-soldering surfaces of the copper substrate are covered with molten tin. The molten tin adhering to the welding and non-welding surfaces of the copper substrate is removed by air knife, and the air knife pressure is controlled so that the tin layer thickness on the non-welding surface is less than the tin layer thickness on the welding surface. The copper substrate is cooled until the tin layer solidifies, resulting in a busbar with a thinner profile on one side.

2. The method for preparing the busbar according to claim 1, characterized in that, The method for preparing the copper substrate includes: Solid copper wire is continuously extracted from molten copper. The solid copper wire is rolled using a cold rolling process to obtain copper wire. The copper wire is rolled to obtain a strip-shaped copper substrate; The rolled copper substrate is treated with an annealing process.

3. The method for preparing the busbar according to claim 2, characterized in that, The annealing process includes: The rolled copper substrate is heated to 550℃-750℃; The heated copper substrate is fed into a cooling water tank at a speed of 90m / min-140m / min and cooled at a temperature of 15℃-25℃.

4. The method for preparing the busbar according to claim 1, characterized in that, Air knives are provided on both the welded and non-welded surfaces of the copper substrate, and the air pressure of the air knife on the welded surface is lower than that of the air knife on the non-welded surface.

5. The method for preparing the busbar according to claim 1, characterized in that, The air pressure of the air knife is less than or equal to 150 kPa, and the air pressure of the air knife on the welded surface is 5 kPa-10 kPa lower than that on the non-welded surface.

6. The method for preparing the busbar according to claim 1, characterized in that, The angle between the air outlet direction of the air knife and the welded and non-welded surfaces of the copper substrate is 55°-60°.

7. The method for preparing the busbar according to claim 1, characterized in that, The tin layer thickness on the non-soldering surface is 5μm-12μm; the tin layer thickness on the soldering surface is greater than 15μm.

8. The method for preparing the busbar according to claim 1, characterized in that, The copper substrate has a width of 4mm-8mm and a thickness of 0.2mm-0.4mm.

9. A busbar, characterized in that, The busbar is prepared by the busbar preparation method according to any one of claims 1-8.

10. A photovoltaic module, characterized in that, It includes a photovoltaic cell and a busbar as described in claim 9, wherein the busbar is connected to the photovoltaic cell.

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