Conductive tape, photovoltaic module and method for manufacturing conductive tape

Abstract

The embodiment of the present application discloses a conductive strip, a photovoltaic module and a preparation method of the conductive strip. The conductive strip comprises a substrate, the substrate has a first side and a second side arranged oppositely, the first side has a light reflection structure, a light reflection layer is arranged on the surface of the light reflection structure, and a welding layer is arranged on the second side. The light reflection layer is formed by electroplating or a non-liquid deposition process. The light reflection layer is formed by electroplating or a non-liquid deposition process (such as vacuum evaporation and magnetron sputtering), the plating layer material is deposited in the form of atoms, ions or gas, and the surface of the light reflection structure is uniformly covered. Compared with a traditional hot-dip tinning process, the accumulation and particles of liquid metal in the groove are reduced, and the original morphology of the light reflection structure is maintained to reduce the adverse effect on the reflectivity.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a conductive strip, a photovoltaic module, and a method for preparing the conductive strip. Background Technology

[0002] Conductive strips are an important component of photovoltaic modules, mainly used to connect cells or cell strings in series or parallel to achieve current collection and transmission.

[0003] In existing technologies, one type of conductive strip uses a copper substrate coated with a tin-lead alloy. To increase the utilization rate of incident light, its reflective surface is typically designed with a serrated reflective structure. However, during the hot-dip tin plating process, traditional interconnect strips suffer from problems such as tin buildup in the bottom trenches of the serrated reflective structure and the presence of tin particles on the surface, which damages the original geometry of the serrated structure. This results in the ineffective utilization of sunlight illuminating the conductive strip, reducing the photoelectric conversion efficiency of the photovoltaic module. The absorbed light energy is not utilized but instead converted into heat energy, causing the temperature of the conductive strip itself and the adjacent cell area to rise, accelerating module aging.

[0004] Another type of conductive strip improves reflectivity by attaching a reflective film to the surface of a conductive substrate. However, the reflective film suffers from problems such as weak adhesion, easy oxidation, or UV aging during long-term use, resulting in a decline in reflectivity and affecting the overall power generation efficiency of the module throughout its lifecycle.

[0005] With the photovoltaic industry's increasing demand for efficiency improvement, how to increase the utilization rate of incident light on the conductive strip surface while ensuring long-term reliability has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] To address the problems of the prior art, this application provides a conductive strip and its preparation method, as well as a photovoltaic module containing the conductive strip, to solve the problem that the conductive strip in the prior art is difficult to balance high reflectivity and long-term reliability.

[0007] In a first aspect, a conductive strip is provided, comprising: a substrate having a first side and a second side disposed opposite to each other, the first side having a reflective structure; a reflective layer disposed on the surface of the reflective structure; and a welding layer disposed on the second side; wherein the reflective layer is formed by an electroplating or non-liquid deposition process.

[0008] In at least some of the embodiments, the reflective structure is one or more of the following: serrated, V-groove, pyramidal, or prism-shaped.

[0009] In at least some of the embodiments, the reflective layer meets at least one of the following criteria: Reflectivity greater than or equal to 80%; Reflectivity greater than or equal to 90%; Materials include silver or aluminum; Purity greater than or equal to 99.9%; Purity greater than or equal to 99.999%; The thickness ranges from 0.01 micrometers to 5 micrometers; The thickness ranges from 0.06 micrometers to 2 micrometers; The thickness is 1 to 2 micrometers.

[0010] In at least some of the embodiments, the non-liquid deposition process is one or more of vacuum evaporation or magnetron sputtering.

[0011] In at least some of the embodiments, the weld layer is formed by a molten liquid metal coating process.

[0012] In at least some of the embodiments, the molten liquid metal coating process includes at least one of hot-dip plating and wave soldering.

[0013] In at least some of the embodiments, the weld layer meets at least one of the following: Materials include tin or tin alloys; The thickness ranges from 10 micrometers to 40 micrometers; The thickness ranges from 15 micrometers to 30 micrometers.

[0014] In at least some of the embodiments, the substrate includes a copper substrate, a copper alloy substrate, or a copper-containing composite substrate.

[0015] In at least some of the embodiments, the conductive strip meets at least one of the following criteria: Tensile strength greater than or equal to 100 MPa; preferably greater than or equal to 150 MPa Elongation greater than or equal to 15%; Yield strength less than or equal to 140 MPa; It is a busbar or interconnecting band.

[0016] The second aspect provides a photovoltaic module, comprising: At least one cell or cell string; a conductive strip, as in any of the first aspects, electrically connected to the cell or cell string via a solder layer.

[0017] In at least some embodiments, the system further includes: a transparent substrate disposed on the first side of the conductive strip, for receiving light reflected by the reflective layer and guiding the light to the battery cell or battery string.

[0018] The third aspect provides a method for preparing a conductive strip, comprising the following steps: A substrate is provided, the substrate having a first side and a second side disposed opposite to each other; A reflective structure with a reflective layer on its surface is formed on the first side; wherein the reflective layer is formed using a non-liquid deposition process; A weld layer is formed on the second side.

[0019] In at least some of the embodiments, the weld layer is formed using a molten liquid metal coating process.

[0020] In at least some of the embodiments, the liquid metal coating process includes at least one of hot-dip plating and wave soldering.

[0021] In at least some of the embodiments, an isolation process is employed before the formation of the weld layer to prevent the reflective layer or the first side from being covered during the formation of the weld layer.

[0022] In at least some of these embodiments, the isolation process prior to the formation of the weld layer includes any of the following: First, a protective layer is set on the first side to form a welding layer. Then, the protective layer is removed to form a reflective layer on the first side. First, a reflective layer is formed, then a protective layer is applied to the surface of the reflective layer, followed by the formation of a welding layer, and finally the removal of the protective layer.

[0023] In at least some of the embodiments, the protective layer is a high-temperature resistant film.

[0024] In at least some embodiments, a reflective layer is first formed, the material of which is a non-tin-adhesive material. A solder layer is then formed without employing an isolation process. The solder layer is made of tin or a tin alloy. A non-tin-adhesive material is a material that does not form compounds upon contact with tin.

[0025] In at least some of the embodiments, the non-tin-adhesive material includes aluminum, and may also include inorganic materials such as UV resin.

[0026] In at least some of the embodiments, after the weld layer is formed, the surface of the reflective layer is cleaned to remove residual weld material adhering to the surface of the reflective layer.

[0027] In at least some of the embodiments, the cleaning process employs air knife blowing or tool wiping.

[0028] In at least some of the embodiments, the reflective structure is formed before the reflective layer is formed.

[0029] In at least some of the embodiments, the reflective structure is formed after the reflective layer is formed.

[0030] In at least some of these embodiments, a protective oil layer is provided on the surface of the reflective layer after the reflective layer is formed and before the reflective structure is formed.

[0031] In at least some of the embodiments, the protective oil layer is removed after the reflective structure is formed.

[0032] In at least some of the embodiments, after the reflective layer is formed, a protective oil layer is provided on the surface of the reflective layer, then a reflective structure is formed, and then a welding layer is formed.

[0033] In at least some of the embodiments, the preparation method is used to prepare a conductive strip forming the first aspect.

[0034] In at least one embodiment provided in this application, the reflective layer is formed using electroplating or non-liquid deposition processes (such as vacuum evaporation or magnetron sputtering). The plating material is deposited layer by layer in atomic, ionic, or gaseous form, which facilitates uniform coverage of the reflective structure's surface. Compared to traditional hot-dip tin plating, this reduces the accumulation and particles of liquid metal in the grooves, helping to maintain the original morphology of the reflective structure and minimize adverse effects on reflectivity.

[0035] In a further embodiment, the reflective layer uses a high-reflectivity metal material such as silver or aluminum, with a reflectivity of over 80%, preferably over 90%, which is much higher than that of traditional tin-lead alloys (below 80%), thus improving reflectivity.

[0036] In further embodiments, this application provides a variety of process paths, such as forming a welding layer first and then forming a reflective layer, or covering the already formed reflective layer with a protective layer when forming the welding layer, thereby reducing welding material residue on the reflective layer.

[0037] Of course, implementing any of the solutions in this application does not necessarily require achieving all of the above advantages at the same time. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In addition, similar numbers in the figures are used to represent similar components, wherein: Figure 1 This is a flowchart of the preparation method in Example 1 of this application; Figure 2 This is a schematic diagram of the product structure corresponding to each step of method 1; Figure 3 This is a flowchart of the preparation method in Example 2 of this application; Figure 4 This is a flowchart of the preparation method in Example 3 of this application; Figure 5 This is a schematic diagram of the conductive strip structure of Embodiment 4 of this application; Figure 6 This is a schematic diagram of the photovoltaic module structure according to Embodiment Six of this application. Detailed Implementation To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Example 1 Embodiment 1 of this application provides a method for preparing a conductive strip. Figure 1 This is a flowchart of the preparation method of Embodiment 1 of this application. Figure 2 This is a schematic diagram of the semi-finished or finished product structure corresponding to each step of Embodiment 1 of this application. (Refer to...) Figure 1 and Figure 2 As shown, the method includes the following steps: S11: Provide substrate.

[0041] like Figure 2 As shown in the first figure, the substrate 100 has a first side 101 and a second side 102 disposed opposite to each other.

[0042] This application does not limit the material of the substrate 100. As an example, and not a limitation, the substrate 100 can be made of copper strip or copper alloy strip, because copper has excellent electrical conductivity and good mechanical strength, which can meet the requirements of photovoltaic modules for the current carrying capacity and mechanical properties of the conductive strip. It should be understood that the substrate 100 can also be made of other materials, as long as they have electrical conductivity. As an example, and not a limitation, the substrate 100 can also be a copper-containing composite substrate, such as a copper-clad aluminum composite substrate. Specifically, the copper-clad aluminum composite substrate includes an aluminum layer and a copper layer, wherein the copper layer includes a first copper layer disposed on at least a portion of the outer peripheral surface of the aluminum layer; in a further example, the copper layer also includes a second copper layer disposed on the inner peripheral surface of the aluminum layer. It should be understood that the copper-clad aluminum composite substrate saves costs by reducing the proportion of copper, but this leads to a decrease in electrical conductivity, which can be compensated for by using the high-reflectivity reflective layer of this application. In a further example, considering conductivity and physical properties, the mass ratio of the first copper layer to the aluminum layer is 1:9 to 9:1, and the thickness of the first copper layer is greater than or equal to 2μm to ensure a certain tensile strength of the substrate 100.

[0043] The embodiments of this application do not limit the cross-sectional shape of the substrate 100. By way of example and not limitation, the substrate 100 can be... Figure 2 The first figure shows a circular substrate. It should be understood that the substrate 100 can also take other shapes, such as a flat substrate, an elliptical substrate, a triangular substrate, or some irregularly shaped substrates.

[0044] S13: A reflective structure is formed on the first side of the substrate.

[0045] like Figure 2 As shown in the second figure, a reflective structure 1011 is formed on the first side 101 of the substrate 100. By way of example and not limitation, the reflective structure 1011 can be formed on the first side 101 by the following specific process: The substrate 100 is drawn into wires, and the drawn substrate 100 is subjected to multiple calendering or drawing processes to form a reflective structure 1011 on the first side 101.

[0046] This application does not limit the specific shape of the reflective structure 1011. As an example and not a limitation, the reflective structure 1011 is serrated. In other embodiments, the reflective structure 1011 may also be a V-groove, a pyramidal shape, or a prism shape, as long as it can achieve the function of directional reflection of light.

[0047] This application does not limit other parameters of the reflective structure 1011. As an example and not a limitation, the angle between adjacent sawtooth reflective structures can be 110° to 130°. Specifically, if the adjacent angle is less than 110°, the light reflection angle is too steep and it is difficult to effectively project onto the light-receiving surface of the battery cell; if it is greater than 130°, the reflection angle is too flat and the light is easily blocked by the adjacent reflective structure 1011.

[0048] As an example and not a limitation, the height of each reflective structure 1011 can be between 30 μm and 50 μm. Specifically, if the height of the reflective structure 1011 is less than 30 μm, the reflective effect is not obvious; if it is greater than 50 μm, it will increase the amount of material used and increase the difficulty of the calendering process.

[0049] It should be understood that the second side 102 of the substrate 100 can be formed into a plane by processes such as calendering.

[0050] S15: A reflective layer is formed on the surface of the reflective structure using electroplating or non-liquid deposition processes.

[0051] like Figure 2 As shown in the third figure, the reflective layer 110 is disposed on the surface of the reflective structure 1011.

[0052] In one example, the coating may be applied only to the surface of the reflective structure 1011 on the substrate 100. In another example, a non-liquid deposition process may be used to coat both the reflective structure 1011 and the second side 102 of the substrate 100 simultaneously. Comparatively, the double-sided coating process is simpler and easier to operate, while the single-sided coating process is less expensive.

[0053] Non-liquid deposition processes refer to processes in which coating materials are deposited layer by layer on the surface of a substrate in the form of atoms, ions, or molecules. This is different from processes such as hot-dip plating or wave soldering, which use molten liquid metal for coating. For example, a non-liquid deposition process is either vacuum evaporation or magnetron sputtering. Non-liquid deposition processes (such as vacuum evaporation) deposit gaseous atoms layer by layer, which can uniformly cover every part of the reflective structure 1011, such as the tip, bevel, and bottom groove, perfectly replicating the microstructure of the reflective structure 1011. This reduces the accumulation and particle problems caused by the flow of liquid metal in traditional hot-dip plating and other liquid metal coating processes, thus helping to reduce the adverse effects of accumulation and particles in the groove on reflectivity.

[0054] As an example, and not a limitation, the thickness of the reflective layer 110 is controlled between 0.01 μm and 5 μm. The thickness of the reflective layer 110 is crucial: if the thickness is less than 0.01 μm, the coating is too thin, making it difficult to form a continuous and dense reflective film, and light may penetrate the coating and be absorbed by the substrate 100, resulting in a decrease in reflectivity; if the thickness is greater than 5 μm, on the one hand, it increases material costs, and on the other hand, an excessively thick coating may fill in the micro-grooves of the reflective structure, destroying the optical design of the sawtooth structure.

[0055] In a further embodiment of this application, the thickness of the reflective layer 110 is controlled between 0.06 μm and 2 μm. In a still further embodiment of this application, the thickness of the reflective layer 110 is controlled between 1 μm and 2 μm. Controlling the thickness within the range of 0.06 μm to 2 μm, or further within the range of 1 μm to 2 μm, is more conducive to forming a continuous and uniform reflective film, and can further reduce the adverse effects of the reflective layer 110 on the original morphology of the reflective structure 1011.

[0056] This application does not impose specific limitations on the material used to form the reflective layer 110. In one example, a material with a reflectivity similar to that of tin or tin-lead can be selected to form the reflective layer 110, as long as it is suitable for a non-liquid deposition process. It should be understood that even if the selected material has a similar reflectivity to tin or tin-lead, the non-liquid deposition process reduces the adverse effects of material buildup in the grooves caused by hot-dip plating on the reflectivity, thus providing better reflectivity. In another example, a material with a reflectivity higher than that of tin or tin-lead can be selected to form the reflective layer 110. By way of example and not limitation, the material of the reflective layer 110 can be selected from at least one of silver and aluminum. Specifically, silver has a visible light reflectivity of up to 95% or even up to 99%, and aluminum has a visible light reflectivity of up to 88% or even up to 92%. Through improvements in both process and material, the reflectivity of the reflective layer 110 can be further improved. For example, by using a vacuum evaporation process to deposit a silver layer on the surface of the reflective structure 1011, an overall reflectivity of over 80% can be achieved. To further improve reflectivity, silver can have a purity of 99% or higher, and even higher than 99.999%. Aluminum can also have a purity of 99% or higher, and even higher than 99.999%.

[0057] In addition, the choice of material for the reflective layer 110 and the aforementioned thickness setting are closely related to the performance parameters of the conductive strip after molding, such as tensile strength, elongation, and yield strength.

[0058] S17: A welding layer is formed on the second side of the substrate.

[0059] like Figure 2 As shown in the fifth figure, a welding layer 120 is formed on the second side 102 of the substrate 100.

[0060] As an example and not a limitation, step S17 specifically employs a liquid metal coating process to form a weld layer 120 on the second side 102. The liquid metal coating process refers to a process that forms a weld layer on the surface of the substrate 100 by bringing the substrate 100 into contact with molten solder. Exemplarily, the liquid metal coating process may include at least one of hot-dip plating and wave soldering. Taking hot-dip plating as an example, the second side 102 of the substrate 100 can be immersed in molten tin or a tin alloy to form a weld layer. During this process, the first side 101 can also be simultaneously immersed in molten tin or a tin alloy. Taking wave soldering as an example, only the second side 102 of the substrate 100 can be coated. Compared to non-molten liquid metal coating processes, the weld layer 120 formed by the molten liquid metal coating process has better adhesion to the substrate 100, meeting the welding performance requirements of photovoltaic modules. Taking hot-dip plating as an example, this process is fast and low-cost.

[0061] It should be understood that, in at least some embodiments, in order to better coat the solder, step S17 further includes applying flux to the second side 102 before coating the solder, and then coating the flux layer to form a solder layer 120.

[0062] In this embodiment, no specific limitations are placed on the material forming the solder layer 120. Specifically, the material of the solder layer 120 can be selected from tin or tin-lead, or other materials suitable for soldering.

[0063] The thickness of the solder layer 120 is not specifically limited in this embodiment. As an example rather than a limitation, the thickness of the solder layer 120 is controlled between 10 μm and 40 μm. The thickness of the solder layer 120 is crucial: if the thickness is less than 10 μm, insufficient solder may result in poor solder joints or insufficient solder strength; if the thickness is greater than 40 μm, it not only increases the cost of solder but may also cause excessive solder to flow and overflow during lamination, affecting the appearance and reliability of the component.

[0064] In a further embodiment of this application, the thickness of the solder layer 120 is controlled between 15 μm and 30 μm. Controlling the thickness within the range of 15 μm to 30 μm is more conducive to forming a continuous and uniform solder layer 120, and can further reduce the adverse effects of excessive solder overflow on the product appearance and reliability.

[0065] In addition, the material selection and thickness setting of the welding layer 120 are closely related to the performance parameters of the formed conductive strip, such as tensile strength, elongation, and yield strength.

[0066] The above steps form a conductive strip 10 with a reflective layer and a welding layer.

[0067] In a further embodiment of this application, reference is made to Figure 1 As shown, the preparation method also includes step S14, which is located after step S13 and before step S15: annealing the substrate.

[0068] Specifically, the substrate 100 can be placed in an annealing furnace for heat treatment to eliminate the internal stress generated during the forming process of the reflective structure 1011 (such as wire drawing and calendering). Annealing transforms the substrate 100 from a hard state to a soft state, improving its flexibility and facilitating subsequent processing.

[0069] It should be understood that although liquid metal coating is only applied to the second side 102 in step S17, some solder may inevitably be mistakenly coated onto the reflective layer 110 of the first side 101 during the coating process, which adversely affects the reflectivity of the reflective layer 110. To reduce the amount of solder mistakenly coated onto the reflective layer 110, in a further embodiment of this application, referring to... Figure 1As shown, the preparation method also includes step S16, which is located after step S15 and before step S17: setting a protective layer on the surface of the reflective layer.

[0070] like Figure 2 As shown in the fourth figure, a protective layer 130 is provided on the surface of the reflective layer 110 to isolate the solder layer. Since the molten solder has a high temperature, in one example, the protective layer 130 is a high-temperature resistant film. Exemplarily, the high-temperature resistant film is a PI film (polyimide film) or an ETFE film (ethylene-tetrafluoroethylene copolymer film), which can be applied to the surface of the reflective layer 110 by means of adhesion. PI and ETFE materials can withstand temperatures from 250°C to 120°C to cope with the high-temperature solder in the liquid metal coating process, and can be easily peeled off after the liquid metal coating process, reducing residue. By providing the protective layer 130, the molten solder can be physically isolated in the subsequent liquid metal coating process, preventing the reflective layer 110 from being contaminated by the solder and affecting its reflectivity.

[0071] In a further embodiment of this application, corresponding to the settings in step S16, refer to... Figure 1 As shown, the preparation method also includes step S18, which is set after step S17: removing the protective layer.

[0072] Specifically, the protective layer 130 is peeled off from the surface of the reflective layer 110 to obtain a conductive strip 10 with the reflective layer 110 on one side and the solder layer 120 on the other side, as shown in the specific structure. Figure 2 As shown in the last image in the series.

[0073] In at least one embodiment of this application, by setting the process, materials and thickness in the above steps, the parameters of the final conductive strip 10 can meet at least one of the following: tensile strength greater than or equal to 100 MPa, preferably greater than or equal to 150 MPa, elongation greater than or equal to 15%, and yield strength less than or equal to 140 MPa.

[0074] The conductive strip 10 with the above parameters is less prone to breakage when subjected to force, less prone to cracking when bent, and reduces the occurrence of poor soldering due to springback during welding with battery cells, etc., caused by high elasticity.

[0075] In the above embodiments, the reflective layer 110 is formed using a non-liquid deposition process, reducing groove buildup and particle issues. The protective layer 130 isolates the reflective layer 110 from the welding layer 120 formation process, ensuring the purity of the reflective layer 110. Using high-purity silver and aluminum as materials for the reflective layer 110 improves the reflectivity of the materials themselves. These three elements work synergistically to comprehensively enhance the reflectivity of the conductive strip 10.

[0076] Example 2 Embodiment 2 of this application provides a method for preparing a conductive strip. Figure 3 This is a flowchart of the preparation method according to Embodiment 2 of this application. (Refer to...) Figure 3 As shown, the preparation method specifically includes the following steps: S31: Provide substrate.

[0077] S33: A reflective structure is formed on the first side of the substrate.

[0078] S35: A reflective layer is formed on the surface of the reflective structure using a non-liquid deposition process.

[0079] S37: A welding layer is formed on the second side of the substrate.

[0080] S39: Clean the surface of the reflective layer.

[0081] In a further embodiment of this application, reference is made to Figure 3 As shown, the preparation method also includes step S34, which is located after step S33 and before step S35: annealing the substrate.

[0082] Unless otherwise specified Figure 3 The specific details of each step S31, S33, S34, S35, and S37 shown can be found in the description of each step S11, S13, S14, S15, and S17 in Embodiment 1, and will not be repeated here.

[0083] The difference from Embodiment 1 is that Embodiment 2 omits step S14 regarding the setting of the protective layer and instead adds step S39, which involves cleaning the surface of the reflective layer after the solder layer is formed to remove any solder that may have adhered to the reflective layer during the solder layer formation process. Exemplarily, methods such as air knife blowing or tool wiping can be used to remove any residual solder that may be adhering to the reflective layer. It should be understood that methods such as air knife blowing or tool wiping have relatively low force and cause less wear to the reflective layer surface, thus preserving as much of the original thickness and morphology of the reflective layer as possible.

[0084] It should be noted that, in the technical solution provided in this application, the degree of adhesion between the reflective layer material and the welding layer material directly affects the ease of cleaning in step S39.

[0085] The applicant discovered through extensive experiments that there are significant differences in the interfacial bonding strength between different metallic materials. Specifically, when the adhesion between the reflective layer material and the welding layer material is weak, the molten solder has poor wettability and is difficult to spread on the reflective layer surface, making it difficult to form a strong metallurgical bond. In this case, even if a protective layer is not applied and the welding layer is formed directly, the amount of solder residue on the reflective layer surface is small, and the bonding force between the residual solder and the reflective layer is weak, making it easy to remove by physical cleaning.

[0086] Based on the above findings, in one embodiment of this application, the reflective layer material in step S35 and the welding layer material in step S37 are selectively matched, specifically selecting a combination of materials with lower adhesion between the two.

[0087] As an example, not a limitation, the soldering layer material is chosen to be tin or a tin alloy, and the reflective layer material is chosen to be a non-tin-adhesive material. A non-tin-adhesive material is one that does not form a compound at the contact interface with tin. The absence of a compound at the contact interface means that the adhesion between the two is relatively weak. For example, aluminum easily forms a dense aluminum oxide film on its surface in air. This oxide film is stable and chemically inert, resulting in a large wetting angle and poor spreadability of molten tin on its surface, making it difficult to form an effective metallurgical bond. Studies have shown that the interfacial bonding strength between aluminum and tin is much lower than the bonding strength of the intermetallic compound (Cu6Sn5) formed between copper and tin. Therefore, when aluminum is used as the reflective layer material and tin or a tin alloy as the soldering layer material, even if a protective layer is not set and the soldering layer is formed directly, the amount of molten tin adhering to the aluminum reflective layer surface is extremely small, and the adhesion between the adhering material and the aluminum surface is weak. Physical cleaning methods such as air knife blowing or tool wiping can effectively remove residual tin from the surface.

[0088] It should be understood that by appropriately selecting the reflective layer material and the welding layer material, a welding layer can be formed directly after the reflective layer, and by adding a cleaning step, solder residue in the reflective layer can be reduced, which helps the reflective layer retain its reflectivity. Compared with the method of adding a protective layer in Example 1, this simplifies the process and reduces production costs.

[0089] It should be understood that when the selected reflective layer material and welding layer material have low adhesion, when forming the reflective layer in step S35, the coating can be applied only to the surface of the reflective structure, and not to the second side of the substrate, so as to avoid the coating affecting the adhesion between the subsequent welding layer and the substrate.

[0090] Example 3 Embodiment 3 of this application provides a method for preparing a conductive strip. Figure 4 This is a flowchart of the preparation method according to Embodiment 3 of this application. (Refer to...) Figure 4 As shown, the preparation method specifically includes the following steps: S41: Provide substrate.

[0091] S43: A reflective structure is formed on the first side of the substrate.

[0092] S45: A weld layer is formed on the second side of the substrate.

[0093] S47: A reflective layer is formed on the surface of a reflective structure using a non-liquid deposition process.

[0094] In a further embodiment of this application, reference is made to Figure 4As shown, the preparation method also includes step S44, which is located after step S43 and before step S45: annealing the substrate.

[0095] Unless otherwise specified Figure 4 The specific details of each step S41, S43, S44, S45, and S47 shown can be found in the description of each step S11, S13, S14, S17, and S15 in Embodiment 1, and will not be repeated here.

[0096] The difference from Embodiment 1 is that Embodiment 3 uses a process sequence of forming the welding layer first, followed by the reflective layer. Since the reflective layer is formed later, there is no need to set a protective layer on the reflective layer as in Embodiment 1.

[0097] It should be noted that the core difference between this embodiment and the aforementioned Embodiment 1 lies in the different process sequence. Embodiment 1 uses the sequence of "forming the reflective layer first, then the welding layer," thus requiring a protective layer to be placed on the surface of the reflective layer to prevent it from being contaminated by solder. In contrast, this embodiment uses the sequence of "forming the welding layer first, then the reflective layer," at which point the reflective layer has not yet been formed, therefore there is no need to place a protective layer on the reflective layer.

[0098] In a further embodiment of this application, considering that during the process of forming the solder layer (e.g., hot-dip tin plating), molten solder may splash or flow to the first side of the substrate and adhere to the surface of the reflective structure. The solder adhering to the surface of the reflective structure may change the original geometry of the reflective structure, destroying the optical design of the reflective structure; at the same time, it may also make the surface of the reflective structure no longer pure, thereby causing at least part of the subsequently formed reflective layer to adhere to the solder surface rather than the substrate surface, resulting in a decrease in the bonding force between the reflective layer and the substrate, affecting the adhesion reliability and long-term stability of the reflective layer.

[0099] Therefore, in a further embodiment, referring to Figure 4 As shown, the preparation method further includes step S440: after substrate annealing in step S44 and before forming the weld layer in step S45, a protective layer is formed on the surface of the reflective structure. For this step, refer to... Figure 4 As shown, the preparation method further includes step S46: removing the protective layer after forming the welding layer in step S45 and before forming the reflective layer in step S47.

[0100] This protective layer acts as a physical barrier, effectively preventing molten solder from contacting the reflective structure surface during the formation of the solder layer. In this way, the solder adheres only to the surface of the protective layer, without directly contacting the reflective structure, thus ensuring the integrity of the original morphology and the purity of the surface. This surface purity allows the reflective layer subsequently formed on the reflective structure to maintain good adhesion and uniform coverage with the substrate, which is beneficial for improving reflectivity.

[0101] In the above embodiments one to three, a process sequence of first forming a reflective structure on the first side of the substrate, and then forming a reflective layer on the surface of the reflective structure, is adopted. It should be understood that this is only one possible example. In another possible example, a process sequence of first forming a reflective layer on the first side of the substrate, followed by processes such as wire drawing and calendering to form the reflective structure, can also be used. Regarding the process sequence of forming a reflective layer first and then forming a reflective structure, in one embodiment of this application, a protective oil layer is provided on the reflective layer after forming the reflective layer and before forming the reflective structure. The function of this protective oil layer is to protect the reflective layer from oxidation or scratches during the subsequent formation of the reflective structure. During the formation of the reflective structure, such as during wire drawing and calendering, the huge mechanical pressure causes the metal to undergo plastic deformation. If the surface of the reflective layer is directly exposed to air, silver or aluminum will react with oxygen to form an oxide film, resulting in a darkened surface and reduced reflectivity; at the same time, friction between the calendering roll and the reflective layer may cause scratches. The protective oil layer serves the dual purpose of isolating air and reducing friction, thereby minimizing the adverse effects of the reflective structure formation process on the reflective layer's performance. In the process of setting the protective oil layer, considering that the weld layer is easily affected during the formation of the reflective structure, such as detaching from the substrate, at least one embodiment of this application forms the reflective structure first, followed by the weld layer. For the treatment of the reflective layer before forming the weld layer, such as setting a protective layer or incorporating a cleaning process, please refer to the relevant descriptions in Embodiments 1 and 2.

[0102] The above are merely examples, and it should be understood that other feasible examples may also be used in the embodiments of this application. In summary, the embodiments of this application provide a method for preparing a conductive strip, comprising the following steps: A substrate is provided, having a first side and a second side disposed opposite to each other; a reflective structure with a reflective layer formed on the surface of the first side and a welding layer formed on the second side. The reflective layer is formed using electroplating or a non-liquid deposition process.

[0103] Example 4 Embodiment 4 of this application provides a conductive strip. Figure 5 This is a schematic diagram of the conductive strip structure according to Embodiment 4 of this application. (Refer to...) Figure 5 As shown, the conductive strip 20 includes a substrate 200, which has a first side 201 and a second side 202. A reflective structure 2011 is provided on the first side 201. In one example, the first side 201 and the second side 202 are arranged opposite to each other.

[0104] Further reference Figure 5 As shown, the conductive strip 20 also includes a reflective layer 210 disposed on the surface of the reflective structure 2011 and a welding layer 220 disposed on the second side 202.

[0105] The conductive strip 20 can be formed using the preparation method of any of the foregoing embodiments, and the performance and parameters of the conductive strip 20 as a whole and its components can be referred to the description of the performance and parameters of the conductive strip 10 as a whole and its components in the foregoing embodiments. As an example and not a limitation, the conductive strip 20 in the embodiments of this application can be applied in photovoltaic modules as a busbar or interconnecting strip to connect cells or battery strings and realize the collection and transmission of current.

[0106] Example 5 Embodiment 5 of this application provides a photovoltaic module. Figure 6 This is a schematic diagram of the photovoltaic module structure according to Embodiment 5 of this application. (Refer to...) Figure 6 As shown, the photovoltaic module 6 includes multiple cells or cell strings 30, a conductive strip 20 as described in Embodiment 4, and a transparent substrate 40.

[0107] Among them, the solar cell or solar string 30 is the power generation unit of the photovoltaic module. Multiple solar cells are connected in series through an interconnecting strip to form a solar string, and multiple solar strings are connected in parallel through a busbar to form the power generation circuit of the photovoltaic module.

[0108] The conductive strip 20 is electrically connected to the solar cell or solar string 30 via a welding layer. Specifically, the welding layer 220 of the conductive strip 20 is welded and fixed to the pads of the solar cell or solar string 30 to achieve current collection and transmission. The first side 201 of the conductive strip 20 faces the light-incident side of the photovoltaic module 6 (i.e., the direction of the transparent substrate 40). This arrangement allows incident light illuminating the surface of the conductive strip 20 to be reflected by the reflective layer 210 instead of being absorbed and wasted.

[0109] A transparent substrate 40 is disposed above the first side 101 of the conductive strip 20 to receive light reflected from the reflective layer 210 and guide the light to the light-receiving surface of the solar cell or solar string 30. In this embodiment, by way of example and not limitation, the transparent substrate 40 is photovoltaic glass, which has good light transmittance and refractive properties, and can further guide the light reflected from the reflective layer 210 to the surface of the solar cell or solar string 30. The refractive index of photovoltaic glass is about 1.5, and light is refracted when it enters the glass from the air, which is beneficial for guiding the reflected light to the light-receiving surface of the solar cell or solar string 30. In other embodiments, the transparent substrate 40 may also be a transparent backsheet.

[0110] During operation, incident light shines onto the surface of the reflective layer 210 of the conductive strip 20. Because the reflective layer 210 has a high reflectivity (≥80%) and uniformly covers the surface of the reflective structure 2011, the light is effectively reflected to the transparent substrate 40. After refraction and transmission through the transparent substrate 40, the light is again guided to the light-receiving surface of the solar cell or solar string 30. Compared with traditional tin-lead solder strips, this application significantly improves the utilization rate of incident light shining on the conductive strip, thereby improving the photoelectric conversion efficiency of the photovoltaic module.

[0111] It should be noted that the relevant parts in the above embodiments one to five of this application can be referred to each other, and the repeated parts will not be described again in this application.

[0112] Tests showed that, under the same process sequence and conditions, compared to the existing hot-dip tin plating method, the reflectivity was improved when the reflective layer was formed using electroplating or non-liquid deposition processes. Furthermore, using silver or aluminum as the reflective layer material further improved the reflectivity. The improvement in reflectivity can reach 10% or even more.

[0113] Using copper strip as the substrate, a reflective layer is formed by electroplating, vacuum evaporation or magnetron sputtering of silver or aluminum, and a solder layer is formed by hot-dip tin plating. Taking the above-mentioned methods of Examples 1 to 3 as examples, the reflectivity of the obtained conductive strip is greater than 85%, and further greater than 90%.

[0114] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A conductive strip, characterized in that, include: A substrate having a first side and a second side disposed opposite to each other, the first side having a reflective structure; A reflective layer is disposed on the surface of the reflective structure; A welding layer is provided on the second side; The reflective layer is formed by electroplating or non-liquid deposition processes.

2. The conductive strip according to claim 1, characterized in that, The reflective structure is one or more of the following: sawtooth, V-groove, pyramidal, or prism-shaped.

3. The conductive strip according to claim 1, characterized in that, The reflective layer meets at least one of the following criteria: Reflectivity greater than or equal to 80%; Reflectivity greater than or equal to 90%; Materials include silver or aluminum; Purity greater than or equal to 99.9%; Purity greater than or equal to 99.999%; The thickness ranges from 0.01 micrometers to 5 micrometers; The thickness ranges from 0.06 micrometers to 2 micrometers; The thickness is 1 to 2 micrometers.

4. The conductive strip according to claim 1, characterized in that, The non-liquid deposition process is one or more of vacuum evaporation or magnetron sputtering.

5. The conductive strip according to claim 1, characterized in that, The weld layer is formed by a molten liquid metal coating process.

6. The conductive strip according to claim 1, characterized in that, The weld layer meets at least one of the following criteria: Materials include tin or tin alloys; The thickness ranges from 10 micrometers to 40 micrometers; The thickness ranges from 15 micrometers to 30 micrometers.

7. The conductive strip according to claim 1, characterized in that, The substrate includes a copper substrate, a copper alloy substrate, or a copper-containing composite substrate.

8. The conductive strip according to claim 1, characterized in that, The conductive strip meets at least one of the following criteria: Tensile strength greater than or equal to 100 MPa; Elongation greater than or equal to 15%; Yield strength less than or equal to 140 MPa; It is a busbar or interconnecting band.

9. A photovoltaic module, characterized in that, include: At least one cell or battery string; The conductive strip as described in any one of claims 1 to 8 is electrically connected to the battery cell or battery string through the welding layer.

10. The photovoltaic module according to claim 9, characterized in that, Also includes: A transparent substrate is disposed on the first side of the conductive strip for receiving light reflected by the reflective layer and guiding the light to the battery cell or battery string.

11. A method for preparing a conductive strip, characterized in that, Includes the following steps: A substrate is provided, the substrate having a first side and a second side disposed opposite to each other; A reflective structure with a reflective layer is formed on the first side and a welding layer is formed on the second side; wherein the reflective layer is formed by electroplating or non-liquid deposition process.

12. The preparation method according to claim 11, characterized in that, The weld layer is formed using a molten liquid metal coating process.

13. The preparation method according to claim 11 or 12, characterized in that, Before the weld layer is formed, an isolation process is used to prevent the reflective layer or the first side from being covered by solder during the formation of the weld layer.

14. The preparation method according to claim 13, characterized in that, The isolation process prior to the formation of the weld layer includes any of the following: First, a protective layer is set on the first side to form the welding layer. Then, the protective layer is removed, and the reflective layer is formed on the first side. First, the reflective layer is formed, then a protective layer is applied to the surface of the reflective layer, then the welding layer is formed, and finally the protective layer is removed.

15. The preparation method according to claim 14, characterized in that, The protective layer is a high-temperature resistant film.

16. The preparation method according to claim 11 or 12, characterized in that, First, the reflective layer is formed. The reflective layer is made of a non-tin-adhesive material. Then, the solder layer is formed without isolation treatment. The solder layer is made of tin or a tin alloy.

17. The preparation method according to claim 16, characterized in that, After the weld layer is formed, the surface of the reflective layer is cleaned to remove any residual welding material adhering to the surface of the reflective layer.

18. The preparation method according to claim 17, characterized in that, The cleaning process involves blowing with an air knife or wiping with a tool.

19. The preparation method according to any one of claims 11 to 18, characterized in that, The reflective structure is formed before the reflective layer is formed.

20. The preparation method according to any one of claims 11 to 18, characterized in that, The reflective structure is formed after the reflective layer is formed.

21. The preparation method according to claim 20, characterized in that, After the reflective layer is formed but before the reflective structure is formed, a protective oil layer is provided on the surface of the reflective layer.

22. The preparation method according to claim 21, characterized in that, After the reflective structure is formed, the protective oil layer is removed.

23. The preparation method according to claim 11, characterized in that, The preparation method is used to prepare the conductive strip according to any one of claims 1 to 8.

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