Method for preparing a solder strip substrate, method for preparing a photovoltaic solder strip

Abstract

This invention discloses a method for preparing a solder ribbon substrate, comprising the following steps: providing an aluminum core; depositing a metal barrier layer on the outer periphery of the aluminum core using an electroplating or chemical plating process; depositing a copper layer on the outer side of the metal barrier layer using an electroplating process; and performing a drawing process on the electroplated wire to obtain the solder ribbon substrate. This invention also discloses a method for preparing a photovoltaic solder ribbon, comprising the following steps: preparing a solder ribbon substrate; and depositing a tin layer on the outer side of the solder ribbon substrate using a hot-dip tin plating or electroplating process. By adding a metal barrier layer between the aluminum core and the copper layer, this invention can actively improve the type of intermetallic compounds, avoid the risk of brittle intermetallic compound formation, enhance the bonding force at the interface between Cu and Al, and prevent delamination between Cu and Al due to bonding force issues.

Description

Technical Field

[0001] This invention belongs to the field of metal processing technology, specifically relating to a method for preparing a solder ribbon substrate and a method for preparing a photovoltaic solder ribbon. Background Technology

[0002] Traditional photovoltaic solder ribbons typically use copper ribbon as the substrate, with a solderable layer formed on its surface through a hot-dip tin plating process. While copper has excellent electrical conductivity, its high density (8.96 g / cm³) presents challenges. 3 The high Young's modulus and overall rigidity of the copper-based solder ribbon result in excessive weight and rigidity. With the increasing trend towards larger and thinner photovoltaic cells (thickness now below 150μm), the mechanical stress generated by the copper-based solder ribbon during module lamination and outdoor thermal cycling is difficult to effectively buffer, easily inducing microcracks in the cells, leading to module power degradation or even scrapping. Furthermore, as a strategic metal, copper experiences volatile prices and continuously rising costs, further increasing the manufacturing costs of photovoltaic modules.

[0003] To address the aforementioned issues, those skilled in the art have attempted to use aluminum strip instead of copper strip as the solder strip substrate. Aluminum has a density of only 2.70 g / cm³. 3 Aluminum has a molecular weight approximately one-third that of copper, and its Young's modulus is also significantly lower than that of copper. Theoretically, using aluminum-based solder ribbon has significant advantages. However, directly applying the traditional hot-dip tin plating process to aluminum-based solder ribbon faces severe technical bottlenecks. The dense oxide film on the aluminum surface is difficult to remove effectively with conventional flux, resulting in uneven wetting and spreading of the molten tin. More importantly, the high temperature of hot-dip tin plating (approximately 240℃~260℃) induces a violent interfacial reaction between aluminum and tin, generating a thick and brittle intermetallic compound (IMC) layer, which seriously affects soldering reliability. Therefore, how to solve the solderability and interfacial stability problems of aluminum-based solder ribbon while retaining the aforementioned theoretical advantages has become a technical direction that urgently needs to be addressed in this field.

[0004] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a method for preparing a solder ribbon substrate and a method for preparing a photovoltaic solder ribbon. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a solder ribbon substrate and a method for preparing a photovoltaic solder ribbon, so as to improve the solderability and interface stability of the solder ribbon substrate.

[0006] To achieve the above objectives, an embodiment of the present invention provides the following technical solution:

[0007] A method for preparing a solder strip substrate includes the following steps:

[0008] Provide aluminum core;

[0009] A metal barrier layer is plated onto the outer periphery of the aluminum core using electroplating or chemical plating processes.

[0010] A copper layer is plated onto the outer side of the metal barrier layer using an electroplating process;

[0011] The electroplated wire is then drawn to obtain a solder strip substrate.

[0012] The thickness of the metal barrier layer after the drawing process is 0.05μm~2μm, and the ratio of the radial dimension of the aluminum core to the thickness of the copper layer in the solder strip substrate after the drawing process is (5~120):1.

[0013] In one or more embodiments of the present invention, the radial dimension of the aluminum core after the drawing process is 0.1 mm to 0.8 mm or 0.1 mm to 0.6 mm; and / or,

[0014] The thickness of the copper layer after the drawing process is 5μm~50μm; and / or,

[0015] The radial dimension of the aluminum core prior to the drawing process is 0.5mm~5mm; and / or,

[0016] The thickness of the copper layer before the drawing process is 20μm~150μm.

[0017] In one or more embodiments of the present invention, the metal barrier layer includes at least one of a nickel layer, a nickel alloy layer, a silver layer, a silver alloy layer, a tin layer, a tin alloy layer, a chromium layer, a chromium alloy layer, a titanium layer, and a titanium alloy layer.

[0018] In one or more embodiments of the present invention, the metal barrier layer is a nickel layer, which is plated using an electroplating process, wherein:

[0019] The electroplating solution is a nickel sulfamate solution of 50 g / L to 250 g / L and a boric acid solution of 20 g / L to 200 g / L; and / or,

[0020] The current density in the electroplating process is 2A / dm. 2 ~20A / dm 2 The electroplating temperature is 30℃~60℃, the pH value is 1.5~4.5, and the thickness of the nickel layer is 0.3μm~10μm.

[0021] In one or more embodiments of the present invention, the metal barrier layer is a nickel-phosphorus alloy layer, which is plated using a chemical plating process, wherein:

[0022] The electroless plating solution comprises a main salt, a reducing agent, a complexing agent, a buffer, and a stabilizer. The main salt is nickel sulfate at 40 g / L to 80 g / L; the reducing agent is sodium hypophosphite at 30 g / L to 60 g / L; the complexing agent is sodium citrate or lactic acid at 60 g / L to 100 g / L; the buffer is sodium acetate at 100 g / L to 200 g / L; and the stabilizer is lead or thiourea at 0.1 g / L to 2 g / L; and / or...

[0023] The electroplating temperature in the electroplating process is 70℃~95℃, the pH value is 4.5~4.9, and the thickness of the nickel-phosphorus alloy layer is 0.3μm~10μm.

[0024] In one or more embodiments of the present invention, in the step of plating a copper layer on the outer side of the metal barrier layer using an electroplating process:

[0025] The electroplating solution is a copper pyrophosphate solution of 50 g / L to 300 g / L and a potassium pyrophosphate solution of 200 g / L to 550 g / L, or the electroplating solution is a copper sulfate solution of 50 g / L to 350 g / L, a sulfuric acid solution of 20 g / L to 250 g / L, and a chloride solution of 0.05 g / L to 1 g / L; and / or,

[0026] In the electroplating process, copper particles with a copper mass fraction greater than 99.9% are used as the anode; and / or,

[0027] The current density during the electroplating process is 5 A / dm³. 2 ~30A / dm 2 The electroplating temperature is 20℃~50℃, the pH value is 0.5~3.5, and the thickness of the copper layer is 20μm~150μm.

[0028] In one or more embodiments of the present invention, prior to the step of plating a metal barrier layer onto the outer periphery of the aluminum core using an electroplating or chemical plating process, the method further includes:

[0029] A metal transition layer is formed on the outer periphery of the aluminum core using a zinc plating process. The metal transition layer is an alloy layer containing zinc and has a thickness of 0.1 μm to 5 μm.

[0030] The thickness of the metal transition layer after the drawing process is 0.01 μm to 1 μm.

[0031] In one or more embodiments of the present invention, the preparation method further includes: performing an oil removal process and / or a descaling process on the surface of the aluminum core; wherein,

[0032] The degreasing process includes: placing the aluminum core in a degreasing solution and performing ultrasonic vibration cleaning to remove oil and foreign matter adhering to the surface of the aluminum core. The processing temperature is 30℃~70℃, the processing time is 0.1min~5min, and the ultrasonic frequency is 10kHz~100kHz.

[0033] The descaling process includes: placing the aluminum core in an acidic descaling solution for acid etching treatment to remove the oxide film on the surface of the aluminum wire. The acidic descaling solution includes an acid solution of 200ml / L to 300ml / L, the treatment temperature is 10℃ to 30℃, and the treatment time is 30s to 60s.

[0034] In one or more embodiments of the present invention, the preparation method further includes:

[0035] The electroplated wire is annealed before and / or after the drawing process at a temperature of 150℃~500℃; and / or,

[0036] Before the drawing process, the electroplated wire is treated with an acid solution to remove oxides from the wire surface; and / or,

[0037] Before the drawing process, the wire is dried at a temperature of 50℃~150℃ to remove moisture from the surface of the wire.

[0038] Another embodiment of the present invention provides the following technical solution:

[0039] A method for preparing a solder strip substrate includes the following steps:

[0040] Provide aluminum cores and perform drawing processes on them;

[0041] A metal barrier layer is plated on the outer periphery of the aluminum core after the drawing process using electroplating or chemical plating.

[0042] A copper layer is plated onto the outer side of the metal barrier layer using an electroplating process to obtain a solder strip substrate.

[0043] The thickness of the metal barrier layer is 0.05μm to 2μm, and the ratio of the radial dimension of the aluminum core to the thickness of the copper layer in the solder strip substrate is (5~120):1.

[0044] In one or more embodiments of the present invention, the radial dimension of the aluminum core before the drawing process is 0.5 mm to 5 mm; and / or,

[0045] After the drawing process, the radial dimension of the aluminum core is 0.1mm~0.8mm or 0.1mm~0.6mm; and / or,

[0046] The thickness of the copper layer is 5μm to 50μm.

[0047] In one or more embodiments of the present invention, the metal barrier layer includes at least one of a nickel layer, a nickel alloy layer, a silver layer, a silver alloy layer, a tin layer, a tin alloy layer, a chromium layer, a chromium alloy layer, a titanium layer, and a titanium alloy layer.

[0048] In one or more embodiments of the present invention, the metal barrier layer is a nickel layer, which is plated using an electroplating process, wherein:

[0049] The electroplating solution is a nickel sulfamate solution of 50 g / L to 250 g / L and a boric acid solution of 20 g / L to 200 g / L; and / or,

[0050] The current density in the electroplating process is 2A / dm. 2 ~20A / dm 2 The electroplating temperature is 30℃~60℃, the pH value is 1.5~4.5, and the thickness of the nickel layer is 0.3μm~10μm.

[0051] In one or more embodiments of the present invention, the metal barrier layer is a nickel-phosphorus alloy layer, which is plated using a chemical plating process, wherein:

[0052] The electroless plating solution comprises a main salt, a reducing agent, a complexing agent, a buffer, and a stabilizer. The main salt is nickel sulfate at 40 g / L to 80 g / L; the reducing agent is sodium hypophosphite at 30 g / L to 60 g / L; the complexing agent is sodium citrate or lactic acid at 60 g / L to 100 g / L; the buffer is sodium acetate at 100 g / L to 200 g / L; and the stabilizer is lead or thiourea at 0.1 g / L to 2 g / L; and / or...

[0053] The electroplating temperature in the electroplating process is 70℃~95℃, the pH value is 4.5~4.9, and the thickness of the nickel-phosphorus alloy layer is 0.3μm~10μm.

[0054] In one or more embodiments of the present invention, in the step of plating a copper layer on the outer side of the metal barrier layer using an electroplating process:

[0055] The electroplating solution is a copper pyrophosphate solution of 50 g / L to 300 g / L and a potassium pyrophosphate solution of 200 g / L to 550 g / L, or the electroplating solution is a copper sulfate solution of 50 g / L to 350 g / L, a sulfuric acid solution of 20 g / L to 250 g / L, and a chloride solution of 0.05 g / L to 1 g / L; and / or,

[0056] In the electroplating process, copper particles with a copper mass fraction greater than 99.9% are used as the anode; and / or,

[0057] The current density during the electroplating process is 5 A / dm³. 2 ~30A / dm 2The electroplating temperature is 20℃~50℃, the pH value is 0.5~3.5, and the thickness of the copper layer is 5μm~50μm.

[0058] In one or more embodiments of the present invention, prior to the step of plating a metal barrier layer onto the outer periphery of the aluminum core after the drawing process using an electroplating or chemical plating process, the method further includes:

[0059] A metal transition layer is formed on the outer periphery of the aluminum core using a zinc plating process. The metal transition layer is an alloy layer containing zinc and has a thickness of 0.01 μm to 1 μm.

[0060] In one or more embodiments of the present invention, the preparation method further includes: performing an oil removal process and / or a descaling process on the surface of the aluminum core after the drawing process; wherein,

[0061] The degreasing process includes: placing the aluminum core in a degreasing solution and performing ultrasonic vibration cleaning to remove oil and foreign matter adhering to the surface of the aluminum core. The processing temperature is 30℃~70℃, the processing time is 0.1min~5min, and the ultrasonic frequency is 10kHz~100kHz.

[0062] The descaling process includes: placing the aluminum core in an acidic descaling solution for acid etching treatment to remove the oxide film on the surface of the aluminum wire. The acidic descaling solution includes an acid solution of 200ml / L to 300ml / L, the treatment temperature is 10℃ to 30℃, and the treatment time is 30s to 60s.

[0063] In one or more embodiments of the present invention, the preparation method further includes:

[0064] The electroplated wire is then annealed at a temperature of 150℃ to 500℃; and / or,

[0065] The electroplated wire is treated with an acid solution to remove oxides from its surface; and / or,

[0066] The electroplated wire is dried at a temperature of 50℃~150℃ to remove moisture from the surface of the wire.

[0067] Another embodiment of the present invention provides the following technical solution:

[0068] A method for preparing photovoltaic solder ribbon, characterized by comprising the following steps:

[0069] The solder strip substrate was prepared using the above-described preparation method;

[0070] A tin layer is plated on the outer side of the solder strip substrate using a hot-dip tin plating process or an electroplating process, and the thickness of the tin layer is 8μm~50μm.

[0071] Compared with the prior art, the solder strip substrate of the present invention has the following technical effects:

[0072] By adding a metal barrier layer between the aluminum core and the copper layer, the type of intermetallic compound can be actively improved, the risk of brittle intermetallic compound formation can be avoided, the bonding force between Cu and Al can be enhanced, and the delamination between Cu and Al due to bonding force problems can be avoided.

[0073] By forming a metal transition layer containing zinc on the surface of the aluminum core, the potential difference between the aluminum core and the metal barrier layer (such as Al and Ni) can be effectively alleviated, the adhesion of subsequent coatings can be improved, and coating peeling can be avoided during subsequent processes.

[0074] By first depositing a film layer on the surface of the aluminum core and then performing the drawing process, the plating efficiency of the metal layer can be improved and the cost reduced. After drawing, porosity is reduced, grains are refined, and the density of the coating is improved. Local atomic diffusion and mechanical interlocking occur between the copper layer and the aluminum core, further increasing the interfacial bonding force between Cu and Al.

[0075] The solder ribbon substrate and photovoltaic solder ribbon can greatly reduce the mass ratio of copper, and the copper layer can achieve a continuous and dense coating effect, avoiding aluminum leakage, insufficient tensile strength of the solder joint, poor soldering or desoldering, thus improving the yield and reliability of the module. Attached Figure Description

[0076] 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.

[0077] Figure 1 This is a schematic diagram of the cross-sectional structure of copper-clad aluminum weld strip in the prior art;

[0078] Figure 2 This is a schematic diagram of the cross-sectional structure of the solder strip substrate in one embodiment of the present invention;

[0079] Figure 3 This is a schematic diagram of the cross-sectional structure of the solder strip substrate in another embodiment of the present invention;

[0080] Figure 4 This is a flowchart of a method for preparing a solder strip substrate according to one embodiment of the present invention;

[0081] Figure 5 This is a flowchart of a method for preparing a solder strip substrate according to another embodiment of the present invention;

[0082] Figure 6This is a flowchart of a method for preparing a solder strip substrate according to another embodiment of the present invention;

[0083] Figure 7 This is a flowchart of a method for preparing a solder strip substrate in another embodiment of the present invention;

[0084] Figure 8 This is a schematic diagram of the cross-sectional structure of a photovoltaic welding strip according to one embodiment of the present invention;

[0085] Figure 9 This is a schematic diagram of the cross-sectional structure of the photovoltaic welding strip in another embodiment of the present invention;

[0086] Figure 10 This is a cross-sectional topography of the solder strip substrate in one embodiment of the present invention;

[0087] Figure 11 This is a topographic image of the aluminum-copper interface in one embodiment of the present invention.

[0088] Explanation of key figure labels:

[0089] 100' - Copper-clad aluminum solder strip, 11' - Aluminum core, 12' - Copper layer, 13' - Tin layer;

[0090] 10-Solder strip substrate, 11-Aluminum core, 12-Metal barrier layer, 13-Copper layer, 14-Metal transition layer;

[0091] 100 - Photovoltaic solder ribbon, 15 - Tin layer. Detailed Implementation

[0092] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0093] In the present invention, unless otherwise clearly specified or limited, the disclosed "range" is defined in the form of a lower limit and / or an upper limit. A given range is defined by selecting a lower limit and / or an upper limit, and the selected lower limit and / or upper limit define the boundary of a specific range. The range defined in this way may include the end values or not include the end values, and any combination can be made, that is, any lower limit can be combined with any upper limit to form a range not explicitly recorded, and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, each individually disclosed point or single value itself can be used as a lower limit or an upper limit and combined with any other point or single value or combined with other lower limits or upper limits to form a range not explicitly recorded.

[0094] In the present invention, the term "and / or" is merely a description of the associative relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0095] In the present invention, unless otherwise clearly specified or limited, all embodiments and optional embodiments, or all technical features and optional technical features can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of this application.

[0096] See Figure 1 As shown, for the copper-clad aluminum (CCA, Copper Clad Aluminum) solder strip 100' in the prior art, a copper layer 12' is compounded on the surface of the aluminum core 11' by mechanical cladding or rolling, and then a tin layer 13' is prepared by hot dip tinning on the copper layer 12'. However, the traditional copper-clad aluminum solder strip still has the following prominent problems in actual application and long-term reliability:

[0097] 1. Risk of brittle fracture. The copper-aluminum interface is prone to generate Cu-Al intermetallic compounds (IMCs) at high temperatures (such as welding, lamination, or outdoor exposure). This compound is hard and brittle, significantly reducing the flexibility of the solder strip. When applied to sensitive solar cells such as TOPCon, the solder strip is extremely likely to break during the string welding and lamination processes, or cause hidden cracks in the solar cells.

[0098] 2. Long-term electrochemistry corrosion risk. There is a potential difference between copper and aluminum. In a humid and hot environment coupled with an electric field, direct contact between copper and aluminum will form a galvanic cell effect, accelerating interface corrosion. This risk is difficult to fundamentally eliminate within the 25-year design life cycle of the component. Under high-temperature exposure, "Kirkendall voids" will occur, resulting in internal pulverization and fracture of the solder tape, and further leading to local failure of the solder tape or abnormal increase in resistance.

[0099] 3. Incomplete coating leads to unreliable welding. Due to processing precision limitations in traditional copper-clad aluminum processes, it is difficult to achieve a copper layer coverage rate of 100%. "Aluminum leakage" is prone to occur locally. The aluminum leakage area cannot be well wetted by solder, directly resulting in insufficient tensile strength, false welding or de-welding at the welding point, seriously affecting the yield and reliability of the component.

[0100] 4. The thickness of the copper layer restricts the cost reduction space. To ensure continuous and dense coating effects and avoid aluminum leakage, traditional copper-clad aluminum processes need to control the copper layer within a relatively thick range (for example, above 80μm), making it difficult to further reduce the thickness. This not only causes waste of copper materials but also limits the potential of aluminum-based lightweight and low cost.

[0101] Based on the above problems, the present invention provides a solder tape substrate and its preparation method. The following provides a detailed description of the solder tape substrate and its preparation method.

[0102] As shown in Figure 2 , the solder tape substrate 10 in an embodiment of the present invention includes:

[0103] An aluminum core 11;

[0104] A metal barrier layer 12, coated on the outer periphery of the aluminum core 11, and the thickness of the metal barrier layer is 0.05μm to 2μm;

[0105] A copper layer 13, coated on the outer periphery of the metal barrier layer 12.

[0106] In some embodiments of the present invention, the aluminum core 11 is an aluminum wire. The cross-section of the aluminum core 11 is circular. The radial dimension of the aluminum core 11, that is, the diameter of the circle, is 0.1mm to 0.8mm. For example, it can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc., or it can be any range composed of the above values. Preferably, the radial dimension of the aluminum core 11 is 0.1mm to 0.6mm, and more preferably, the radial dimension of the aluminum core 11 is 0.15mm to 0.25mm.

[0107] In other embodiments of the present invention, the cross-section of the aluminum core 11 can also be other shapes. For example, the cross-section of the aluminum core can be rectangular, with a maximum side length of 0.1mm to 0.8mm, preferably 0.1mm to 0.6mm, and more preferably 0.15mm to 0.25mm. Alternatively, the cross-section of the aluminum core can be triangular, with a maximum side length of 0.1mm to 0.6mm, preferably 0.1mm to 0.6mm, and more preferably 0.15mm to 0.25mm. Another example is that the cross-section of the aluminum core can be a flat shape, with a width of 0.1mm to 0.8mm, preferably 0.1mm to 0.6mm, and more preferably 0.15mm to 0.25mm. The cross-sectional shape of the aluminum core 11 can be arbitrary, and will not be described in detail here.

[0108] In some embodiments of the present invention, the copper layer is an electroplated copper layer with a thickness of 5μm to 50μm, for example, it can be 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, etc., or it can be any range of the above values. More preferably, the copper layer thickness is 8μm to 25μm.

[0109] In some embodiments of the present invention, the ratio of the radial dimension of the aluminum core 11 to the thickness of the copper layer 13 is (5~120):1, for example, it can be 5:1, 10:1, 20:1, 40:1, 60:1, 80:1, 100:1, 120:1, etc., or it can be a range of any of the above values. Preferably, by controlling the ratio of the radial dimension of the aluminum core to the thickness of the copper layer, the weight percentage of copper can be reduced to 30% or less, which can significantly reduce manufacturing costs.

[0110] In some embodiments of the present invention, the metal barrier layer 12 includes at least one of the following: a nickel layer (Ni), a nickel alloy layer (such as a nickel-phosphorus alloy Ni-P), a silver layer (Ag), a silver alloy layer, a tin layer (Sn), a tin alloy layer (such as Sn-Ag-Cu, Sn-Ag-Ti), a chromium layer (Cr), a chromium alloy layer, a titanium layer (Ti), and a titanium alloy layer; or it may be a multilayer metal barrier layer stacked structure.

[0111] In some embodiments of the present invention, the thickness of the metal barrier layer 12 is 0.05 μm to 2 μm, for example, it can be 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, etc., or it can be a range of any of the above values. More preferably, the thickness of the metal transition layer 14 is 0.2 μm to 0.8 μm.

[0112] The above metal barrier layer 12 has good compatibility with the aluminum core 11 and the copper layer 13 and can effectively reduce the melting of the substrate, which is an ideal barrier material. Through the action of the metal barrier layer 12, the type of intermetallic compound can be actively improved, the risk of generating brittle intermetallic compounds can be avoided, the bonding force of the interface between Cu and Al can be enhanced, the delamination caused by the bonding force problem between Cu and Al can be avoided, and finally the electrical connection between Al and Cu can be achieved. It can also effectively avoid material segregation and residual stress, thereby effectively suppressing cracks and stabilizing electrical performance.

[0113] See Figure 10 and Figure 11 As shown, in a specific embodiment of the present invention, the thickness of the nickel barrier layer in the solder strip substrate is 1.49 μm, and the thickness of the copper layer is 33.2 μm. The copper layer and the aluminum core can achieve good bonding and will not form delamination due to bonding force problems.

[0114] See Figure 3 As shown, the solder strip substrate 10 in another embodiment of the present invention further includes a metal transition layer 14 in addition to the aluminum core 11, the metal barrier layer 12 and the copper layer 13. The metal transition layer 14 is disposed between the outer periphery of the aluminum core 11 and the inner periphery of the metal barrier layer 12, and the metal transition layer 14 is an alloy layer containing metal zinc.

[0115] In some embodiments of the present invention, the thickness of the metal transition layer 14 is 0.01 μm to 1 μm, for example, it can be 0.01 μm, 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, etc., or it can be any range composed of the above values. More preferably, the thickness of the metal transition layer 14 is 0.01 μm to 0.5 μm.

[0116] By preparing a metal transition layer 14 containing metal zinc on the outer periphery of the aluminum core 11, the potential difference between the aluminum core 11 and the metal barrier layer 12 (such as Al and Ni) can be effectively alleviated, the adhesion of the subsequent plating layer can be enhanced, and the situation of plating layer peeling off during the subsequent process can be avoided.

[0117] See Figure 2 and in combination with Figure 4 As shown, the preparation method of the solder strip substrate in an embodiment of the present invention includes the following steps:

[0118] S11. Provide the aluminum core 11;

[0119] S12. Coat the metal barrier layer 12 on the outer periphery of the aluminum core 11 by electroplating or chemical plating;

[0120] S13. Coat the copper layer 13 on the outside of the metal barrier layer 12 by electroplating;

[0121] S14. The electroplated wire is drawn to obtain the solder strip substrate 10.

[0122] In step S11 of some embodiments of the present invention, the aluminum core 11 is not drawn, and the initial radial dimension of the aluminum core 11 is 0.5mm to 5mm. For example, when the aluminum core 11 is an aluminum wire, the cross-section of the aluminum core 11 is circular, and the initial radial dimension of the aluminum core 11 is the diameter of the circle. For example, it can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc., or it can be a range of any of the above values.

[0123] In step S12 of some embodiments of the present invention, the metal barrier layer 12 is plated on the outer periphery of the aluminum core 11 using an electroplating process.

[0124] For example, in the electroplating process of the nickel layer:

[0125] The electroplating solution is a nickel aminosulfonate solution of 50 g / L to 250 g / L and a boric acid solution of 20 g / L to 200 g / L;

[0126] The current density in the electroplating process is 2A / dm. 2 ~20A / dm 2 The electroplating temperature is 30℃~60℃, the pH value is 1.5~4.5, and the thickness of the nickel layer is 0.3μm~10μm.

[0127] In step S12 of some embodiments of the present invention, the metal barrier layer 12 is plated on the outer periphery of the aluminum core 11 using a chemical plating process.

[0128] In some embodiments of the present invention, the metal barrier layer is a nickel-phosphorus alloy layer. The metal barrier layer is a nickel-phosphorus alloy layer. The electroplating solution in the electroplating process includes a solution of a main salt, a reducing agent, a complexing agent, a buffer, and a stabilizer. The main salt is used to provide Ni ions, the reducing agent is used to reduce Ni ions and co-deposit phosphorus, the complexing agent can be used to prevent nickel precipitation and stabilize the plating solution, the buffer is used to maintain pH stability, and the stabilizer is used to inhibit spontaneous decomposition of the electroplating solution.

[0129] For example, in the electroless plating process of the nickel-phosphorus alloy layer:

[0130] The main salt is nickel sulfate at 40 g / L to 80 g / L, the reducing agent is sodium hypophosphite at 30 g / L to 60 g / L, the complexing agent is sodium citrate or lactic acid at 60 g / L to 100 g / L, the buffer is sodium acetate at 100 g / L to 200 g / L, and the stabilizer is lead or thiourea at 0.1 g / L to 2 g / L.

[0131] The electroplating temperature in the electroplating process is 70℃~95℃, the pH value is 4.5~4.9, and the thickness of the nickel-phosphorus alloy layer is 0.3μm~10μm.

[0132] In some embodiments of the present invention, after the metal barrier layer 12 is plated by electroplating or chemical plating in step S12, the method further includes:

[0133] Water washing: Rinse with deionized water to remove residual medicine and prevent contamination of subsequent processes;

[0134] Passivation: Nickel-free passivating agent is used to further improve corrosion resistance;

[0135] Drying: Use hot air at 60℃~80℃ to dry and prevent water stains from remaining.

[0136] In step S13 of some embodiments of the present invention, the copper layer 13 is plated on the outer periphery of the metal barrier layer 12 using an electroplating process.

[0137] For example, in the electroplating process of copper layers:

[0138] The electroplating solution is a copper pyrophosphate solution of 50 g / L to 300 g / L and a potassium pyrophosphate solution of 200 g / L to 550 g / L, or the electroplating solution is a copper sulfate solution of 50 g / L to 350 g / L, a sulfuric acid solution of 20 g / L to 250 g / L and a chloride solution of 0.05 g / L to 1 g / L.

[0139] Copper particles with a copper mass fraction greater than 99.9% are used as the anode during the electroplating process;

[0140] The current density during the electroplating process is 5 A / dm³. 2 ~30A / dm 2 The electroplating temperature is 20℃~50℃, the pH value is 0.5~3.5, and the thickness of the copper layer is 20μm~150μm.

[0141] Furthermore, the aluminum core surface can be pretreated before step S12, including degreasing and descaling processes.

[0142] In some embodiments of the present invention, the degreasing process includes:

[0143] The aluminum core is placed in a degreasing solution and ultrasonically cleaned to remove oil and foreign matter adhering to the surface of the aluminum core. The treatment temperature is 30℃~70℃, the treatment time is 0.1min~5min, and the ultrasonic frequency is 10kHz~100kHz.

[0144] The degreasing process uses ultrasonic vibration and saponification reaction, while the cleaning process employs ultrasonic cleaning to thoroughly remove contaminants such as drawing oil and emulsions remaining during the aluminum core rolling or drawing process, ensuring uniform wetting of the aluminum wire surface and creating clean conditions for subsequent descaling.

[0145] In some embodiments of the present invention, the descaling process includes:

[0146] The aluminum core is placed in an acidic descaling solution for acid etching to remove the oxide film on the surface of the aluminum wire. The acidic descaling solution consists of an acid solution of 200 ml / L to 300 ml / L, the treatment temperature is 10℃ to 30℃, and the treatment time is 30s to 60s.

[0147] The degreased aluminum core is immersed in an acidic descaling solution for acid treatment. The natural dense oxide film (Al2O3) on the surface of the aluminum core is completely removed by chemical dissolution, and the aluminum substrate is slightly etched to expose a fresh active aluminum surface. This creates a uniform micro-rough surface on the aluminum core, which improves the adhesion of subsequent coatings.

[0148] In step S14 of some embodiments of the present invention, the drawing process includes multiple drawing passes to finally obtain a solder strip substrate with a target radial dimension.

[0149] In some embodiments of the present invention, the radial dimension of the aluminum core 11 before the drawing process is 0.5 mm to 5 mm, the thickness of the metal barrier layer 12 is 0.3 μm to 10 μm, and the thickness of the copper layer 13 is 20 μm to 150 μm.

[0150] In some embodiments of the present invention, the radial dimension of the aluminum core 11 after the drawing process is 0.1 mm to 0.6 mm, the thickness of the metal barrier layer 12 is 0.05 μm to 2 μm, and the thickness of the copper layer 13 is 5 μm to 50 μm.

[0151] In some embodiments of the present invention, the drawing process includes multiple drawing passes, and the process further includes the following steps before or after at least one drawing pass:

[0152] The wire is annealed at a temperature of 150℃ to 500℃.

[0153] After the wire is drawn, the internal grains are continuously refined and gradually transformed into a fibrous deformed structure. Annealing at a temperature of 150℃~500℃ allows the crystals to recrystallize, which can improve the comprehensive performance of the solder strip substrate, such as tensile strength, electrical conductivity, elongation, etc., and further reduce the brittleness caused by subsequent processing.

[0154] In some embodiments of the present invention, before the drawing process, the electroplated wire is treated with an acid solution to remove the oxides on the surface of the wire. Exemplarily, a sulfuric acid solution with a concentration of 1 g / L to 5 g / L can be used for surface treatment of the wire.

[0155] In some embodiments of the present invention, the wire is dried before the drawing process. Exemplarily, an electric heating oven is used for drying, and the drying temperature is 50°C to 150°C to remove the moisture on the surface of the wire.

[0156] It should be noted that after the drawing process, the thickness of the coatings (nickel barrier layer and copper layer) on the surface of the aluminum core will have a certain loss. The loss rate η is about 1% to 5%, usually about 3%. Taking one layer of coating as an example, the thickness of the coating after the drawing process = (the thickness of the original coating * the total diameter after the drawing process) / the total diameter before the drawing process * (1 - loss rate).

[0157] See Figure 3 and in combination with Figure 5 As shown, the preparation method of the solder strip substrate in another embodiment of the present invention includes the following steps:

[0158] S21. Provide an aluminum core 11;

[0159] S22. Form a metal transition layer 14 on the outer periphery of the aluminum core 11 by a zinc immersion process. The metal transition layer is an alloy layer containing metallic zinc;

[0160] S23. Coat a metal barrier layer 12 on the outer periphery of the metal transition layer 14 by an electroplating process or a chemical plating process;

[0161] S24. Coat a copper layer 13 on the outside of the metal barrier layer 12 by an electroplating process;

[0162] S25. Perform a drawing process on the electroplated wire to obtain the solder strip substrate 10.

[0163] In some embodiments of the present invention, steps S21, S23, S24, and S25 are exactly the same as the above steps S11, S12, S13, and S14, and will not be elaborated here.

[0164] In step S22 of some embodiments of the present invention, a binary zinc immersion process or a quaternary zinc immersion process can be used to prepare a binary zinc alloy layer or a quaternary zinc alloy layer. The thickness of the metal transition layer is 0.1 μm to 5 μm, preferably 0.2 μm to 1 μm. After the drawing process in step S25, the thickness of the metal transition layer is 0.01 μm to 1 μm, preferably 0.01 μm to 0.5 μm.

[0165] The zinc deposition agent is the core chemical reagent for realizing the zinc deposition process. Its main components include zinc salts, complexing agents, stabilizers, and possible additives (such as copper, iron, nickel ions for forming a multi-element alloy layer). Adding organic additives such as sodium citrate, sodium lactate, and ethylene thiourea can effectively inhibit grain coarsening and make the zinc alloy layer thinner and denser.

[0166] In the above preparation method, by first plating a film layer on the surface of the aluminum core and then performing the drawing process, the plating efficiency of the metal layer can be improved and the cost can be reduced. After drawing, the pores can be reduced, the grains can be refined, and the compactness of the coating can be improved. Local atomic diffusion and mechanical interlocking occur between the copper layer and the aluminum core, further increasing the interfacial bonding force between Cu and Al.

[0167] In some embodiments of the present invention, the zinc deposition process in step S22 is carried out in the pre-treatment process of the aluminum core. The pre-treatment includes a degreasing process and a scale removal process. Preferably, the zinc deposition process is carried out after the degreasing process and before the scale removal process. By forming a uniform zinc alloy layer on the aluminum surface through the zinc deposition process, the potential difference between the aluminum core and the metal barrier layer (such as Al and Ni) can be effectively alleviated, the adhesion of the subsequent coating can be improved, and the situation of coating peeling off in the subsequent process can be avoided.

[0168] See Figure 2 and in combination with Figure 6 As shown, the preparation method of the solder strip substrate in another embodiment of the present invention includes the following steps:

[0169] S31. Provide an aluminum core 11 and perform a drawing process on the aluminum core 11;

[0170] S32. Use electroplating or chemical plating to coat a metal barrier layer 12 on the outer circumference of the aluminum core 11 after the drawing process;

[0171] S33. Use electroplating to coat a copper layer 13 on the outside of the metal barrier layer 12.

[0172] In some embodiments of the present invention, the radial dimension of the aluminum core 11 before the drawing process is 0.5 mm to 5 mm, and the radial dimension of the aluminum core 11 after the drawing process is 0.1 mm to 0.6 mm.

[0173] In some embodiments of the present invention, the thickness of the metal barrier layer 12 is 0.05 μm to 2 μm, and the thickness of the copper layer 13 is 5 μm to 50 μm.

[0174] In this embodiment, first, a drawing process is performed on the aluminum core 11, and then a metal barrier layer 12 and a copper layer 13 are coated on the surface of the drawn aluminum core. The difference is only in the coating thicknesses of the metal barrier layer 12 and the copper layer 13, and the rest are the same as the previous embodiments, so they will not be elaborated here.

[0175] See Figure 3 and in combination with Figure 7 As shown, a method for preparing a solder ribbon substrate in another embodiment of the present invention includes the following steps:

[0176] S41. Provide an aluminum core 11 and perform a drawing process on the aluminum core 11;

[0177] S42. Use a zinc immersion process to form a metal transition layer 14 on the outer periphery of the aluminum core 11 after the drawing process. The metal transition layer is an alloy layer containing metallic zinc;

[0178] S43. Use an electroplating process or a chemical plating process to coat a metal barrier layer 12 on the outer periphery of the metal transition layer 14;

[0179] S44. Use an electroplating process to coat a copper layer 13 on the outside of the metal barrier layer 12.

[0180] In some embodiments of the present invention, steps S41, S43, and S44 are completely the same as the above steps S31, S32, and S33, and will not be elaborated here.

[0181] In step S42 of some embodiments of the present invention, a binary zinc immersion process or a quaternary zinc immersion process can be used to prepare a binary zinc alloy layer or a quaternary zinc alloy layer. The thickness of the metal transition layer is 0.01 μm to 1 μm, preferably 0.01 μm to 0.5 μm.

[0182] Refer Figure 8 、 Figure 9 As shown, a photovoltaic solder ribbon 100 in an embodiment of the present invention includes the aforementioned solder ribbon substrate 10, and further includes a tin layer 15 coated on the outer periphery of the solder ribbon substrate. The thickness of the tin layer 15 is 8 μm to 50 μm, for example, it can be 8 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, etc., or it can be any range composed of the above values.

[0183] In some embodiments of the present invention, the tin layer 15 is coated by a hot-dip tinning process or an electroplating process. The process of coating the tin layer 15 by the hot-dip tinning process or the electroplating process belongs to the existing process. Exemplarily, a tin layer with a thickness of 8 μm to 50 μm can be coated by the hot-dip tinning process, preferably with a thickness of 10 μm to 18 μm.

[0184] In some embodiments of the present invention, the photovoltaic solder ribbon is applied to a photovoltaic module. The photovoltaic module includes multiple groups of parallel-connected battery strings, and each battery string includes multiple series-connected solar cells. Among them, the photovoltaic solder ribbon can be a photovoltaic interconnection solder ribbon (also called an interconnection ribbon) for connecting multiple solar cells in series; the photovoltaic solder ribbon can also be a photovoltaic busbar solder ribbon (also called a busbar or a busbar strip) for connecting multiple battery strings in parallel.

[0185] The photovoltaic module of this invention can be made of any of the following types of cells: PERC cell (passivated emitter and back cell), PERT cell (passivated emitter back surface fully diffused cell), TOPCon cell (tunneling oxide passivated contact cell), HIT / HJT cell (heterojunction cell), perovskite cell, and BC cell (back contact cell). The BC cell can be IBC cell (cross-back electrode contact cell), HPBC cell (composite passivated back contact photovoltaic cell), TBC cell with TOPCon and IBC technologies, or HBC cell with HIT / HJT and IBC technologies. Of course, it can also be other types of back contact photovoltaic cells.

[0186] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0187] Comparative Example 1 (Traditional Coating Method):

[0188] In this comparative example, the solder strip substrate is... Figure 1 The substrate of the copper-clad aluminum brazing strip 100' includes an aluminum core 11' and a copper layer 12'. The aluminum core 11' has an initial diameter of 1.5 mm, and the copper layer 12' is prepared by mechanical cladding or rolling, with an initial thickness of 140 μm.

[0189] In this comparative example, after the solder strip substrate undergoes a drawing process, the diameter of the aluminum core 11' is 0.23 mm and the thickness of the copper layer 12' is 15 μm.

[0190] Comparative Example 2 (Ordinary Direct Plating Method):

[0191] The solder strip substrate in this comparative example includes an aluminum core and a copper layer, and the preparation method includes:

[0192] Provide aluminum core;

[0193] A copper layer is directly plated onto the outer side of the aluminum core using an electroplating process;

[0194] The electroplated wire is then drawn to obtain the solder strip substrate.

[0195] Compared with Comparative Example 1, the initial thickness of the copper layer can be reduced by 5% to 10%, to 45 μm to 160 μm, and the initial diameter of the aluminum core is 0.6 mm to 1.5 mm.

[0196] In this comparative example, after the solder strip substrate undergoes a drawing process, the diameter of the aluminum core is 0.23 mm and the thickness of the copper layer is 15 μm.

[0197] Example 1:

[0198] The solder strip substrate in this embodiment is Figure 2 The solder strip substrate shown is made of Figure 4The preparation method described in the text is followed by a hot-dip tin plating process to prepare a tin layer, resulting in... Figure 8 The photovoltaic welding strip shown.

[0199] In this embodiment, the solder strip substrate 10 includes an aluminum core 11, a metal barrier layer 12, and a copper layer 13. The aluminum core 11 has a circular cross-section, and the metal barrier layer 12 is a nickel barrier layer.

[0200] The thickness of the tin layer 15 in the photovoltaic solder ribbon 100 is 12μm.

[0201] Table 1 shows the performance test results of photovoltaic ribbons obtained from different sizes of ribbon substrates:

[0202] Table 1: Performance Tests of Different Photovoltaic Spinners

[0203]

[0204] Example 2:

[0205] The solder strip substrate in this embodiment is Figure 3 The solder strip substrate shown is made of Figure 5 The preparation method described in the text is followed by a hot-dip tin plating process to prepare a tin layer, resulting in... Figure 9 The photovoltaic welding strip shown.

[0206] In this embodiment, the solder strip substrate 10 includes an aluminum core 11, a metal transition layer 14, a metal barrier layer 12, and a copper layer 13. The aluminum core 11 has a circular cross-section, the metal barrier layer 12 is a nickel barrier layer, and the metal transition layer 14 is a zinc alloy layer.

[0207] The thickness of the tin layer 15 in the photovoltaic solder ribbon 100 is 12μm.

[0208] Table 2 shows the performance test results of photovoltaic ribbons obtained from different sizes of ribbon substrates:

[0209] Table 2: Performance Tests of Different Photovoltaic Strips

[0210]

[0211] Example 3:

[0212] The solder strip substrate in this embodiment is Figure 2 The solder strip substrate shown is made of Figure 6 The preparation method described in the text is followed by a hot-dip tin plating process to prepare a tin layer, resulting in... Figure 8 The photovoltaic welding strip shown.

[0213] In this embodiment, the solder strip substrate 10 includes an aluminum core 11, a metal barrier layer 12, and a copper layer 13. The aluminum core 11 has a circular cross-section, and the metal barrier layer 12 is a nickel barrier layer.

[0214] The thickness of the tin layer 15 in the photovoltaic solder ribbon 100 is 12μm.

[0215] Table 3 shows the performance test results of photovoltaic ribbons obtained from different sizes of ribbon substrates:

[0216] Table 3: Performance Tests of Different Photovoltaic Strips

[0217]

[0218] Example 4:

[0219] The solder strip substrate in this embodiment is Figure 3 The solder strip substrate shown is made of Figure 7 The preparation method described in the text is followed by a hot-dip tin plating process to prepare a tin layer, resulting in... Figure 9 The photovoltaic welding strip shown.

[0220] In this embodiment, the solder strip substrate 10 includes an aluminum core 11, a metal transition layer 14, a metal barrier layer 12, and a copper layer 13. The aluminum core 11 has a circular cross-section, the metal barrier layer 12 is a nickel barrier layer, and the metal transition layer 14 is a zinc alloy layer.

[0221] The thickness of the tin layer 15 in the photovoltaic solder ribbon 100 is 12μm.

[0222] Table 4 shows the performance test results of photovoltaic ribbons obtained from different sizes of ribbon substrates:

[0223] Table 4: Performance Tests of Different Photovoltaic Strips

[0224]

[0225] As can be seen from Tables 1 to 4 above, by adding a metal barrier layer between the aluminum core and the copper layer, the risk of brittle intermetallic compound formation can be avoided, the bonding force between Cu and Al interfaces can be improved, the peel strength of the Cu-Al interface and the tensile strength of the welding point can be significantly improved, thereby improving the electrical performance of the photovoltaic ribbon.

[0226] In addition, by forming a zinc alloy layer on the surface of the aluminum core, the potential difference between the aluminum core and the metal barrier layer (such as Al and Ni) can be effectively alleviated, the adhesion of subsequent coatings can be improved, and the peel strength of the Cu-Al interface and the pull strength of the weld point can be further improved.

[0227] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure 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 this disclosure 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 this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0228] 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 solder strip substrate, characterized in that, Includes the following steps: Provide aluminum core; A metal barrier layer is plated onto the outer periphery of the aluminum core using electroplating or chemical plating processes. A copper layer is plated onto the outer side of the metal barrier layer using an electroplating process; The electroplated wire is then drawn to obtain a solder strip substrate. The thickness of the metal barrier layer after the drawing process is 0.05μm~2μm, and the ratio of the radial dimension of the aluminum core to the thickness of the copper layer in the solder strip substrate after the drawing process is (5~120):

1.

2. The method for preparing the solder strip substrate according to claim 1, characterized in that, After the drawing process, the radial dimension of the aluminum core is 0.1mm~0.8mm or 0.1mm~0.6mm; and / or, The thickness of the copper layer after the drawing process is 5μm~50μm; and / or, The radial dimension of the aluminum core prior to the drawing process is 0.5mm~5mm; and / or, The thickness of the copper layer before the drawing process is 20μm~150μm.

3. The method for preparing the solder strip substrate according to claim 1, characterized in that, The metal barrier layer includes at least one of the following: nickel layer, nickel alloy layer, silver layer, silver alloy layer, tin layer, tin alloy layer, chromium layer, chromium alloy layer, titanium layer, and titanium alloy layer.

4. The method for preparing the solder strip substrate according to claim 1, characterized in that, The metal barrier layer is a nickel layer, plated using an electroplating process. In the electroplating process: The electroplating solution is a nickel sulfamate solution of 50 g / L to 250 g / L and a boric acid solution of 20 g / L to 200 g / L; and / or, The current density in the electroplating process is 2A / dm. 2 ~20A / dm 2 The electroplating temperature is 30℃~60℃, the pH value is 1.5~4.5, and the thickness of the nickel layer is 0.3μm~10μm.

5. The method for preparing the solder strip substrate according to claim 1, characterized in that, The metal barrier layer is a nickel-phosphorus alloy layer, plated using a chemical plating process. In the chemical plating process: The electroless plating solution comprises a main salt, a reducing agent, a complexing agent, a buffer, and a stabilizer. The main salt is nickel sulfate at 40 g / L to 80 g / L; the reducing agent is sodium hypophosphite at 30 g / L to 60 g / L; the complexing agent is sodium citrate or lactic acid at 60 g / L to 100 g / L; the buffer is sodium acetate at 100 g / L to 200 g / L; and the stabilizer is lead or thiourea at 0.1 g / L to 2 g / L; and / or... The electroplating temperature in the electroplating process is 70℃~95℃, the pH value is 4.5~4.9, and the thickness of the nickel-phosphorus alloy layer is 0.3μm~10μm.

6. The method for preparing the solder strip substrate according to claim 1, characterized in that, In the step of plating a copper layer on the outside of the metal barrier layer using an electroplating process: The electroplating solution is a copper pyrophosphate solution of 50 g / L to 300 g / L and a potassium pyrophosphate solution of 200 g / L to 550 g / L, or the electroplating solution is a copper sulfate solution of 50 g / L to 350 g / L, a sulfuric acid solution of 20 g / L to 250 g / L and a chloride solution of 0.05 g / L to 1 g / L. And / or, In the electroplating process, copper particles with a copper mass fraction greater than 99.9% are used as the anode; and / or, The current density during the electroplating process is 5 A / dm³. 2 ~30A / dm 2 The electroplating temperature is 20℃~50℃, the pH value is 0.5~3.5, and the thickness of the copper layer is 20μm~150μm.

7. The method for preparing the solder strip substrate according to claim 1, characterized in that, Before the step of plating a metal barrier layer onto the outer periphery of the aluminum core using electroplating or chemical plating processes, the following steps are also included: A metal transition layer is formed on the outer periphery of the aluminum core using a zinc plating process. The metal transition layer is an alloy layer containing zinc and has a thickness of 0.1 μm to 5 μm. The thickness of the metal transition layer after the drawing process is 0.01 μm to 1 μm.

8. The method for preparing the solder strip substrate according to claim 7, characterized in that, The preparation method further includes: performing an oil removal process and / or a descaling process on the surface of the aluminum core; wherein... The degreasing process includes: placing the aluminum core in a degreasing solution and performing ultrasonic vibration cleaning to remove oil and foreign matter adhering to the surface of the aluminum core. The processing temperature is 30℃~70℃, the processing time is 0.1min~5min, and the ultrasonic frequency is 10kHz~100kHz. The descaling process includes: placing the aluminum core in an acidic descaling solution for acid etching treatment to remove the oxide film on the surface of the aluminum wire. The acidic descaling solution includes an acid solution of 200ml / L to 300ml / L, the treatment temperature is 10℃ to 30℃, and the treatment time is 30s to 60s.

9. The method for preparing the solder strip substrate according to claim 1, characterized in that, The preparation method further includes: The electroplated wire is annealed before and / or after the drawing process at a temperature of 150℃~500℃; and / or, Before the drawing process, the electroplated wire is treated with an acid solution to remove oxides from the wire surface; and / or, Before the drawing process, the wire is dried at a temperature of 50℃~150℃ to remove moisture from the surface of the wire.

10. A method for preparing a solder strip substrate, characterized in that, Includes the following steps: Provide aluminum cores and perform drawing processes on them; A metal barrier layer is plated on the outer periphery of the aluminum core after the drawing process using electroplating or chemical plating. A copper layer is plated onto the outer side of the metal barrier layer using an electroplating process to obtain a solder strip substrate. The thickness of the metal barrier layer is 0.05μm to 2μm, and the ratio of the radial dimension of the aluminum core to the thickness of the copper layer in the solder strip substrate is (5~120):

1.

11. The method for preparing the solder strip substrate according to claim 10, characterized in that, The radial dimension of the aluminum core prior to the drawing process is 0.5mm~5mm; and / or, After the drawing process, the radial dimension of the aluminum core is 0.1mm~0.8mm or 0.1mm~0.6mm; and / or, The thickness of the copper layer is 5μm to 50μm.

12. The method for preparing the solder strip substrate according to claim 10, characterized in that, The metal barrier layer includes at least one of the following: nickel layer, nickel alloy layer, silver layer, silver alloy layer, tin layer, tin alloy layer, chromium layer, chromium alloy layer, titanium layer, and titanium alloy layer.

13. The method for preparing the solder strip substrate according to claim 10, characterized in that, The metal barrier layer is a nickel layer, plated using an electroplating process. In the electroplating process: The electroplating solution is a nickel sulfamate solution of 50 g / L to 250 g / L and a boric acid solution of 20 g / L to 200 g / L; and / or, The current density in the electroplating process is 2A / dm. 2 ~20A / dm 2 The electroplating temperature is 30℃~60℃, the pH value is 1.5~4.5, and the thickness of the nickel layer is 0.3μm~10μm.

14. The method for preparing the solder strip substrate according to claim 10, characterized in that, The metal barrier layer is a nickel-phosphorus alloy layer, plated using a chemical plating process. In the chemical plating process: The electroless plating solution comprises a main salt, a reducing agent, a complexing agent, a buffer, and a stabilizer. The main salt is nickel sulfate at 40 g / L to 80 g / L; the reducing agent is sodium hypophosphite at 30 g / L to 60 g / L; the complexing agent is sodium citrate or lactic acid at 60 g / L to 100 g / L; the buffer is sodium acetate at 100 g / L to 200 g / L; and the stabilizer is lead or thiourea at 0.1 g / L to 2 g / L; and / or... The electroplating temperature in the electroplating process is 70℃~95℃, the pH value is 4.5~4.9, and the thickness of the nickel-phosphorus alloy layer is 0.3μm~10μm.

15. The method for preparing the solder strip substrate according to claim 10, characterized in that, In the step of plating a copper layer on the outside of the metal barrier layer using an electroplating process: The electroplating solution is a copper pyrophosphate solution of 50 g / L to 300 g / L and a potassium pyrophosphate solution of 200 g / L to 550 g / L, or the electroplating solution is a copper sulfate solution of 50 g / L to 350 g / L, a sulfuric acid solution of 20 g / L to 250 g / L and a chloride solution of 0.05 g / L to 1 g / L. And / or, In the electroplating process, copper particles with a copper mass fraction greater than 99.9% are used as the anode; and / or, The current density during the electroplating process is 5 A / dm³. 2 ~30A / dm 2 The electroplating temperature is 20℃~50℃, the pH value is 0.5~3.5, and the thickness of the copper layer is 5μm~50μm.

16. The method for preparing the solder strip substrate according to claim 10, characterized in that, Before the step of plating a metal barrier layer on the outer periphery of the aluminum core after the drawing process using electroplating or chemical plating, the process further includes: A metal transition layer is formed on the outer periphery of the aluminum core using a zinc plating process. The metal transition layer is an alloy layer containing zinc and has a thickness of 0.01 μm to 1 μm.

17. The method for preparing the solder strip substrate according to claim 10, characterized in that, The preparation method further includes: performing an oil removal process and / or a descaling process on the surface of the aluminum core after the drawing process; wherein... The degreasing process includes: placing the aluminum core in a degreasing solution and performing ultrasonic vibration cleaning to remove oil and foreign matter adhering to the surface of the aluminum core. The processing temperature is 30℃~70℃, the processing time is 0.1min~5min, and the ultrasonic frequency is 10kHz~100kHz. The descaling process includes: placing the aluminum core in an acidic descaling solution for acid etching treatment to remove the oxide film on the surface of the aluminum wire. The acidic descaling solution includes an acid solution of 200ml / L to 300ml / L, the treatment temperature is 10℃ to 30℃, and the treatment time is 30s to 60s.

18. The method for preparing the solder strip substrate according to claim 10, characterized in that, The preparation method further includes: The electroplated wire is then annealed at a temperature of 150℃ to 500℃; and / or, The electroplated wire is treated with an acid solution to remove oxides from its surface; and / or, The electroplated wire is dried at a temperature of 50℃~150℃ to remove moisture from the surface of the wire.

19. A method for preparing photovoltaic solder ribbon, characterized in that, Includes the following steps: The solder strip substrate is prepared by the preparation method according to any one of claims 1 to 18; A tin layer is plated on the outer side of the solder strip substrate using a hot-dip tin plating process or an electroplating process, and the thickness of the tin layer is 8μm~50μm.

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