A solder strip tin plating secondary forming process

Abstract

The present application relates to a kind of solder strip tin plating secondary forming process, which comprises the following steps: step 1, tin layer is horizontally pre-coated on the surface of copper strip, and the amount of tin is controlled;Step 2, the copper strip with tin layer is water-cooled for the first time;Step 3, the tin layer and the copper strip are realized secondary concentricity by leveling member smearing;Step 4, the copper strip with tin layer is water-cooled for the second time.The forming process reduces the difficulty of primary forming, uses rolling friction, the resistance is small, and is suitable for the production of different photovoltaic solder strips such as round solder strip, flat solder strip and special-shaped solder strip.Using the forming process, the solder strip has small resistance, timely tension transmission, and the whole system is stable and controllable, so it can be used for tin plating operation at high speed.

Description

Technical Field

[0001] This invention belongs to the field of solar photovoltaic technology, and specifically relates to a secondary forming process for solder strip tin plating. Technical Background

[0002] The current market is witnessing the continuous emergence of new photovoltaic module technologies, with micro-circular solder ribbon (MBB) becoming the mainstream. The entire module packaging technology and manufacturing process are fully mature and will enter a period of stable mass production.

[0003] Currently, the trend in the industry is towards finer solder strips. Circular MBB (≥9BB) solder strips remain the mainstream welding technology for modules. However, with the increasing size of mainstream solar cells and process upgrades, multi-busbar MBB, with its greater cost-reduction potential, is expected to see accelerated adoption, increasing the number of mainstream busbars from 9-12 to 15-18. As the solder strip is responsible for collecting current in solar cells, smaller cross-section circular solder strips are sufficient. Furthermore, with the rise of various module technologies, even finer circular solder strips will be tested by customers, and 0BB technology will have a demand for circular solder strips with a diameter of less than 0.2mm.

[0004] In the existing solder strip manufacturing process, traditional hot-dip tinning involves vertically pulling copper wire through molten tin and using molds or air knives to control the thickness of the surface tin layer, followed by air cooling. This tinning process is simple and short, but with the continuous increase in production speed, its drawbacks have gradually become apparent: 1) There is static friction between the copper wire and the pressure roller / plate, resulting in high friction. Long-term use can cause wear and tear on the grooves of the pressure roller / plate. The residual flux on the pressure plate is difficult to clean, leading to wire jamming, unstable tension, and continuous wire vibration; 2) Air cooling is ultimately indirect cooling with low heat exchange efficiency. Under high-speed operation, the cooling distance needs to be increased, resulting in larger and taller equipment that is uncoordinated. Moreover, increased cooling height is less conducive to the transmission of wire tension; 3) With increased speed, the amount of tin on the wire increases. If the air knife cannot remove the excess tin layer in time or the force is insufficient, bamboo-like tin nodules will form on the surface. Traditional vertical hot-dip galvanizing processes have reached a bottleneck, making it imperative to research new and suitable preparation processes and develop new equipment.

[0005] Among the currently published patents: CN202025576U discloses a horizontal tinning device for ultra-fine copper wires, targeting copper wires smaller than 0.1mm, but lacks specific tinning process details, and does not address thickness control or wire cooling methods after tinning; CN212894927U discloses a photovoltaic solder ribbon cooling system, CN20640972U discloses a device for tinning photovoltaic solder ribbons, CN213053166U discloses a round solder ribbon anti-vibration device for cooling air ducts, and CN115161577A discloses a high-efficiency cooling device for photovoltaic solder ribbons. All of these use air cooling to cool the solder ribbons. However, air cooling is indirect, resulting in low heat exchange efficiency. Under high-speed wire operation, the cooling distance needs to be increased, leading to larger and taller equipment that is uncoordinated. Furthermore, increased cooling height further hinders the transmission of wire tension. The apparatus disclosed in 115740955A for producing zero-stress MBB photovoltaic solder ribbon adds a texturing step to the surface of copper wire in the traditional production mode to improve product characteristics; the induction annealing solder ribbon production equipment disclosed in CN 218311323U directly puts the annealed copper wire into the tin-lead alloy. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to propose a secondary forming process for solder ribbon tin plating, which reduces the difficulty of primary forming. Using this forming process, the wire resistance is low, the tension is transmitted in a timely manner, and the whole system is stable and controllable, which is beneficial for tin plating operations at high speeds.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A secondary forming process for tin plating of solder strip, wherein the solder strip is a copper strip, characterized by comprising: step 1, applying a horizontal pre-coating of tin layer to the surface of the copper strip and controlling the amount of tin applied; step 2, subjecting the copper strip with the tin layer to a first water cooling; step 3, achieving secondary concentricity between the tin layer and the copper strip by applying the tin layer through a leveling component; and step 4, subjecting the copper strip with the tin layer to a second water cooling.

[0008] Furthermore, before applying a horizontal tin layer to the copper strip surface in step 1, flux is uniformly applied to the copper strip surface.

[0009] Preferably, the specific process of step 1 is as follows: the copper strip passes horizontally through the molten tin in the tin coating bath, and then passes through the tin control mold.

[0010] Preferably, both the first and second water cooling are circulating water cooling.

[0011] Furthermore, the circulating water temperature for the first water cooling is 50-80℃, and the circulating water temperature for the second water cooling is 20-30℃.

[0012] Furthermore, in step 3, before applying the tin layer to the leveling component, the tin-copper strip is heated a second time.

[0013] Preferably, the secondary heating process is as follows: a copper strip with a tin layer enters the induction heating tube vertically downwards.

[0014] Preferably, the leveling component is a leveling mold or an annular air knife.

[0015] Furthermore, after the copper strip with the tin layer undergoes the first and second water cooling processes, the water stains on the surface of the tin layer are blown off by an air brush.

[0016] Furthermore, the copper strip is driven by rolling friction.

[0017] Compared with the prior art, the advantages of the present invention are as follows: This invention uses a horizontal tin plating method, first controlling the amount of tin applied to the copper strip surface with a mold, and then reheating the surface tin layer in a subsequent process to perform a secondary finishing of the surface, thus reducing the difficulty of one-time forming.

[0018] This invention uses water cooling to directly cool the tin layer, reducing the cooling height and length of the equipment, while also facilitating the transmission of wire tension; This invention employs rolling friction during the copper strip tin plating process, resulting in low resistance, timely tension transmission, and high-speed production friendliness for micro-solder strips. It is also applicable to the production of various photovoltaic solder strips, including round solder strips, flat solder strips, and irregularly shaped solder strips. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the secondary forming process of horizontal tin plating on solder strips according to the present invention; Attached reference numerals: 1. Copper strip, 2. Flux bath, 3. Tin coating bath, 4. Mold eye, 5. Circulating water at 50℃-80℃, 6. Air brush, 7. Induction heating tube, 8. Circulating water at 20-30℃, 9. Nitrogen protection tube. Specific Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] refer to Figure 1 A secondary forming process for solder strip tin plating includes: Step 1: The traction wheel drives the copper strip 1 through the flux tank 2. After the surface is evenly coated with flux, it passes horizontally through the molten solder in the solder coating tank 3 and then through the solder control mold at the outlet of the solder coating tank 3. After the copper strip is pulled away from the solder solution, the liquid solder, under the action of gravity, forms a thinner upper semicircle and a thicker lower semicircle on the surface of the copper strip 1. When passing through the solder control mold, the size of the die eye 4 of the solder control mold can control the amount of solder on the surface of the copper strip 1. Step 2: After the copper strip 1 with tin layer passes through the tin control mold, the traction wheel continues to drive the copper strip 1 with tin layer into the circulating water 5 at 50℃-80℃ for the first cooling, so that the molten tin on the surface is initially solidified. An air brush 6 is set at the water outlet to blow away the water stains on the surface of the tin layer. Step 3: The traction wheel pulls the tin-coated copper strip 1 vertically downwards into the induction heating tube 7. The leveling mold or air knife at the outlet of the induction heating tube 7 evenly coats the tin layer on the copper strip 1, achieving secondary leveling, making the tin layer surface smooth and concentric with the copper strip 1. The amount of tin on the copper strip 1 with the tin layer is constant, but its concentricity varies greatly, requiring secondary leveling of the tin layer. Under the action of the high-frequency alternating magnetic field in the induction heating tube 7, the copper strip 1 is heated again, and the tin layer on the surface melts and flows downwards with the traction direction. The concentric air knife or leveling mold set on the lower side of the heating chamber evenly coats the tin layer on the surface of the copper strip 1. During the secondary leveling process, since the traction direction of the copper strip 1 is the same as the direction of gravity, the molten tin on its surface will no longer move laterally.

[0022] Step 4: After the tin layer has been leveled twice, it enters the circulating water 8 at 20-30℃ with the copper strip 1 for a second cooling. After the second cooling, the tin layer solidifies. After the water stains on the surface of the tin layer are blown off by the air brush set at the water outlet, the copper strip 1 with the tin layer is wound into a roll, and the solder strip tinning is completed.

[0023] In the above embodiments, the flux tank 2 and the circulating cooling water tank are welded with PVC material and use magnetic circulation pumps and PPR pipelines for water circulation; the tin coating tank 3 is made of titanium alloy with a double-layer structure design. The tin control mold at the outlet of the upper tin coating tank is made of stainless steel, and its center hole diameter is 5μ larger than the actual required size.

[0024] During the secondary leveling process, the medium- and high-frequency power supply acts on the inductor in the induction heating tube 7, causing the area to generate a high-frequency alternating magnetic field to induction heat the copper strip. Nitrogen gas protection is provided in the heating zone to prevent the copper and tin from being oxidized. The height of the nitrogen protection tube 9 is greater than the height of the induction heating tube 7. The leveling mold or air knife at the end of the heating zone is used to homogenize the tin layer.

[0025] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A secondary forming process for tin-plated solder strips, wherein the solder strip is a copper strip, characterized in that, Includes the following steps: Step 1: Apply a horizontal pre-coating of tin to the surface of the copper strip, controlling the amount of tin applied; Step 2: Perform the first water cooling on the copper strip with the tin layer; Step 3: By leveling the components and applying the tin, the concentricity of the tin layer and the copper strip is achieved; Step 4: Perform a second water cooling on the copper strip with the tin layer; In step 3, before applying the tin layer to the leveling component, the tin-coated copper strip is heated a second time. The specific process of the second heating is as follows: the tin-coated copper strip enters the induction heating tube vertically downward.

2. The secondary forming process for solder strip tin plating according to claim 1, characterized in that, Before applying a horizontal tin layer to the copper strip surface in step 1, flux is evenly applied to the copper strip surface.

3. The secondary forming process for solder strip tin plating according to claim 1, characterized in that, The specific process of step 1 is as follows: the copper strip passes horizontally through the molten tin in the tin coating bath, and then passes through the tin control mold.

4. The secondary forming process for solder strip tin plating according to claim 1, characterized in that, Both the first and second water cooling processes use circulating water cooling.

5. The secondary forming process for solder strip tin plating according to claim 4, characterized in that, The circulating water temperature for the first water cooling is 50-80℃, and the circulating water temperature for the second water cooling is 20-30℃.

6. The secondary forming process for solder strip tin plating according to claim 1, characterized in that, The leveling component is a leveling mold or an annular air knife.

7. The secondary forming process for solder strip tin plating according to claim 1, characterized in that, After the copper strip with the tin layer was subjected to the first and second water cooling, the water stains on the surface of the tin layer were blown off by an air brush.

8. The secondary forming process for solder strip tin plating according to claim 1, characterized in that, The copper strip is driven by rolling friction.

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