Copper pre-brazed electroplating nickel for heat exchanger

Abstract

Systems and methods for pre-brazing a heat exchanger are provided. A method of forming a heat exchanger is described that includes pre-treating one or more copper sheets (including a blank and a coil), electroplating nickel on the one or more copper sheets, stamping a heat exchanger component with the one or more nickel-plated copper sheets; and brazing the stamped nickel plated component of the heat exchanger.

Description

Technical Field

[0001] This description generally relates to a method for nickel plating a copper heat exchanger component prior to brazing. Background and Summary

[0002] Heat exchangers used to cool automotive (especially electric and hybrid vehicles) electronics can be made of copper or aluminum components that are joined together by brazing. Copper and aluminum each have their advantages and disadvantages, so depending on the application, one of them may be more suitable. For example, the advantage of copper is its relatively high thermal conductivity, which means that a copper heat exchanger can transfer heat from electrical components more effectively than an aluminum heat exchanger. However, when the heat transfer requirements are lower, an aluminum heat exchanger may be more preferred because the cost and weight of aluminum are relatively lower than those of copper. Therefore, it may be necessary to use a combination of a copper brazed heat exchanger (CBHE) and an aluminum brazed heat exchanger (ABHE) in a system. For example, an aluminum brazed heat exchanger can be used to cool a traction battery, while a copper brazed heat exchanger can be used to cool an electrical inverter, and both heat exchangers can be in contact with a common cooling fluid. When used simultaneously, an electrochemical reaction may occur between the CBHE and the ABHE through the coolant acting as an electrolyte, resulting in copper degradation. Copper heat exchangers may also degrade under other conditions.

[0003] To provide corrosion protection and delay coolant degradation, CBHEs are typically electroplated, such as nickel plating. In current production methods, the nickel plating is performed after brazing or assembling the components, usually by electroless plating. Electroless nickel plating uses a chemical reducing agent in solution to deposit nickel ions on the inner surface of the copper heat exchanger, such as flow channels where electrolytic plating cannot meet the requirements.

[0004] However, post-plating nickel also has some disadvantages. One disadvantage is that the electroless nickel plating process places limitations on the design of the CBHE because the CBHE needs to balance the efficiency of the heat exchanger and the plating quality (such as uniform and precise thickness). For example, since electroless plating relies on solution flow to evenly deposit nickel ions on the copper surface, the geometry and size of the internal flow channels may be restricted (such as diameter and / or length) to maintain sufficient flow of the plating solution. Therefore, although electroless plating is more effective than electrolytic plating, electroless plating still limits the effectiveness of the heat exchanger. Another disadvantage of post-brazing plating is that the brazed joints may be damaged during the pre-treatment process before nickel plating, thereby affecting the structural integrity and performance of the CBHE after nickel plating. In addition, post-brazing plating may cause impurities, such as metal particles, to appear in the heat exchanger formed after post-brazing plating. Since the cleanliness of the heat exchanger (such as no impurities) is a factor for the heat exchanger to function properly in many applications, including the thermal regulation of electronic devices, a heat exchanger with impurities generated due to post-brazing plating may not meet the standards of proper performance.

[0005] In one embodiment, at least part of the above problems can be solved by plating nickel on copper and forming nickel-plated copper into nickel-plated copper components before brazing the heat exchanger. In certain embodiments, the copper billet can be pretreated before nickel plating and then stamped into parts. These components can then be assembled and brazed to form a CBHE. In other embodiments, other forms of copper or copper alloys can be used in addition to the copper billet. In this way, various forms of CBHE can be achieved by nickel plating before brazing. In addition, electroplating before brazing eliminates design limitations, such as those on the flow channels, and the heat exchanger can be further optimized as long as the electroplating thickness is within a certain range required for brazing strength. Compared with post-brazing electroplating where ion deposition on irregular surfaces (such as sharp corners) is involved, electroplating before brazing can also improve the consistency of the electroplating thickness throughout the heat exchanger. In addition, compared with post-brazing electroplating, pre-brazing electroplating can reduce the degradation of the brazed joints during pretreatment and can reduce the resource requirements for electroplating. In addition, pre-brazing electroplating can reduce impurities, resulting in a higher cleanliness than post-brazing electroplating. By studying the materials through metallographic inspection techniques, the differences in nickel diffusion and electroplating structure between pre-brazing electroplated and post-brazing electroplated heat exchangers can be determined. Finally, the cost of manufacturing a heat exchanger by pre-brazing electrolytic electroplating may be lower than the related cost of post-brazing electroless electroplating.

[0006] In addition, pre-brazing electroplating also has some related advantages, and electrolytic electroplating can be carried out instead of electroless electroplating. For example, electrolytic electroplating can use pure nickel, while electroless electroplating uses phosphorus in addition to nickel. Therefore, electrolytic electroplating can make the electroplated material have higher conductivity and lower heat resistance, so that the CBHE electroplated by this method has better performance and durability.

[0007] For all the above reasons, pre-heating electroplating nickel may be an advantageous method compared with the current post-electroplating nickel technology when manufacturing CBHEs for cooling automotive electronic devices and heat exchangers for various other uses. In addition, when forming nickel-plated copper component assemblies for uses other than heat conduction, it may be necessary to perform pre-treatment of electroplating nickel on copper.

[0008] It should be understood that the above summary is to introduce in a simplified form concepts further described in the detailed description. It is not intended to identify the key or essential features of the claimed subject matter, the scope of which is uniquely determined by the claims that follow the detailed description. In addition, the claimed subject matter is not limited to embodiments that solve any disadvantages noted above or in any part of this disclosure. Brief Description of the Drawings

[0009] Figure 1 A flowchart of a method for pre-brazing nickel plating on copper is shown, and this method can be used to form a CBHE.

[0010] Figure 2 Shows an exemplary embodiment of a copper blank in the steps of a pre-brazing nickel plating method.

[0011] Figure 3 Shows an exemplary embodiment of a copper coil in the steps of a pre-brazing nickel plating method.

[0012] Figure 4 Shows a continuous production line for manufacturing a CBHE with pre-brazing nickel plating.

[0013] Figure 5 Shows a cross-section of a CBHE brazed joint that has been electroplated before brazing.

[0014] Figure 6 Shows an exemplary embodiment of a CBHE.

[0015] Figure 7A Shows an example of a metallographic inspection image of a heat exchanger formed by a post-electroplating nickel process.

[0016] Figure 7B Shows an example of a metallographic inspection image of a heat exchanger formed by a pre-brazing nickel plating process (such as Figure 1 the method). Detailed description

[0017] The following disclosure relates to a method for manufacturing a heat exchanger or other nickel-plated copper components by pre-brazing nickel plating on copper. The method may include pretreatment, electrolytic electroplating, stamping, assembly, and brazing. Compared with nickel plating after brazing on copper, nickel plating before brazing can reduce design limitations, lower the demand for manufacturing resources, eliminate the degradation of the brazed joint during the pretreatment of the post-brazing nickel plating process, and make the coating thickness more uniform. The "copper" used herein may refer to pure copper and / or copper alloy materials, and similarly, "nickel" may refer to pure nickel metal and / or nickel alloy materials.

[0018] Figure 1 Shows a method for pre-brazing nickel plating on unformed copper parts (such as copper coils or copper blanks) and / or copper components, which can form a CBHE. As described above, the copper sheet and / or copper components can be pure copper and / or copper alloy. Figure 2 and Figure 3 Shows Figure 1 examples of materials before and after the method steps, starting from copper blanks and copper coils respectively. Figure 4 Shows an example of an assembly line in which the continuous process implements Figure 1 the method to manufacture a nickel-plated CBHE. Figure 5 Shows an example of a brazed joint of a CBHE, such as Figure 6 the CBHE shown, which is by a pre-brazing electroplating method (such asFigure 1 formed by the method). In Figures 2 - 6 , nickel is shown in shadow. Figure 7A and Figure 7B respectively show example images of the post-glazed heat exchanger and the pre-glazed heat exchanger obtained through metallographic inspection, for comparing the resulting structures.

[0019] Reference Figure 1 , the figure shows Method 100 for pre-brazing nickel plating on copper. For example, Method 100 can be used to form a CBHE. In other examples, the pre-brazed nickel-plated copper components can be assembled into assemblies using Method 100 for other applications other than heat transfer. The starting copper piece of Method 100 can be an unformed copper piece. For example, the starting unformed copper piece of Method 100 can be in the form of a copper coil, such as Figure 3 the copper coil 302 in Figure 3 . The copper coil applicable to Method 100 can be a flat rectangular material (such as Figure 3 the unrolled copper coil 304 in Figure 3 ), rolled into a cylindrical shape so that the short ends (such as end 310) can be accessed on the outside of the coil. The copper coil can include various dimensions, such as length (such as Figure 2 the length 314 of the unrolled copper coil 304 in

[0020] Forming a CBHE using Method 100 can be completed by a continuous assembly line, such as Figure 4Assembly line 400 therein. In some embodiments, the copper starting piece 410 can take any of the above forms and can move along a path 416 in the direction specified by arrow 414 to each of the pretreatment unit 402, the electroplating unit 404, the stamping unit 406, and the brazing unit 408, thereby forming the nickel-plated CBHE 412. The nickel-plated CBHE 412 can have various forms depending on the starting material and the final stamped part. For example, the nickel-plated CBHE 412 can be a brazed plate heat exchanger composed of multiple nickel-plated copper plates and other components (such as Figure 6 the brazed plate heat exchanger 600 therein). The assembly line 400 can be an automated process, a series of steps completed manually, or a combination of them. The assembly line can simplify the production of CBHE and help improve efficiency. Additionally, the CBHE can be formed individually by method 100 rather than in a continuous process such as Figure 4 the assembly line 400 therein.

[0021] Returning to Figure 1 , method 100 first selectively unwinds the copper coil at 102. Since the starting copper sheet can be a coil and / or a blank and / or a CBHE component, this step can be performed when the coil needs to be electroplated. In other words, if the starting copper sheet is not a coil, such as a blank and / or a pre-stamped element, 102 may not be completed. Unwinding the copper coil may result in an unwound copper coil, such as a long, flat rectangular copper sheet (e.g., Figure 3 the unwound copper coil 304 therein). The unwinding of the copper coil can be achieved by an automatic and / or manual process that is part of a continuous assembly line, such as before or as part of the pretreatment device 402 in Figure 4 assembly line 400. In some examples, the copper coil can be rotated to a different direction than that shown in Figure 3 before unwinding. Since the copper surface is exposed in the unwound form, the unwound copper material may be more suitable for nickel plating than the wound copper material.

[0022] Method 100 continues to 104, where the copper is pretreated to ensure proper quality of electroplating. The starting copper raw material may contain impurities such as dust, oil, grease, oxides, and other foreign substances that can interfere with normal electroplating. Therefore, pretreatment is required at 104 to remove such substances from the copper surface to ensure the adhesion and durability of the nickel plating layer. The pretreatment can include cleaning the unformed copper starting piece (such as Figure 2 the copper blank 202 therein and / or Figure 3the copper coil 302). The cleaning agent used in the pretreatment process may include an acidic cleaning agent and chemicals that are active on the copper surface. Other suitable pretreatment methods may also be used to remove impurities and prepare for copper electroplating. The pretreatment can be carried out in the pretreatment unit of a continuous assembly line, such as Figure 4 the pretreatment unit 402 of the assembly line 400 shown

[0023] After 104, method 100 proceeds to 106 for electroplating the pretreated copper. Electroplating may include placing the pretreated copper material (such as Figure 2 the copper blank 202 in Figure 3 the unwound copper coil 304 in or the pretreated pre-stamped copper assembly) and a piece of nickel or nickel alloy into an electroplating electrolyte solution and continuously applying an electric current so that the copper acts as the cathode and the nickel acts as the anode. In this way, nickel ions can be deposited onto the copper, causing the nickel ions to be evenly distributed in a nickel plating layer of a certain thickness on the copper surface, where the thickness of the nickel plating layer can be within a certain range to successfully braze the CBHE in subsequent steps and ensure pressure durability and corrosion resistance. The lower limit of the thickness range can prevent the nickel plating layer from being too thin, thereby reducing the corrosion resistance. The upper limit of the thickness range can ensure that the brazing filler metal can diffuse through the nickel coating to obtain a strong brazed joint, which will be further discussed. For example, the lower limit of the thickness range can be 0.5 μm, and the upper limit of the thickness range can be 5 μm. In other words, the thickness of the nickel coating can be greater than or equal to 0.5 μm to obtain sufficient corrosion protection and / or less than or equal to 5 μm to obtain a brazed joint with sufficient strength. In another example, the thickness range can be between 1 to 4 μm, 2 to 3 μm, or 1.5 to 2.5 μm to improve corrosion protection in applications more exposed to degradation elements (e.g., aluminum and ordinary coolant as the electrolyte) and / or a higher degradation rate (e.g., due to changes in the pH value and / or temperature of the coolant as the electrolyte) and allow an ideal tolerance for the filler diffusion distance accuracy. In some examples, the thickness range can be between 0.5 microns and 2 microns, within which the brazed joint strength is the greatest. The amount of nickel in the electroplating electrolyte can be determined (e.g., calculated, estimated) based on the equipment scale and / or the dimensional specifications of the CBHE design (including mass and surface area). The nickel can be pure nickel or a nickel alloy can be used. The electroplating electrolyte solution may contain nickel sulfate and / or other suitable compounds. Electroplating may include one or more types of electroplating (such as barrel plating, rack plating, continuous electroplating, in-line electroplating, etc.) and can be part of a continuous assembly line, such as Figure 4 the electroplating unit 404 of the assembly line 400 in Figure 4Electrolytic plating unit 404 in the electrolytic plating unit. For example, there can be one electrolytic plating unit for each type of copper starting material (e.g., blank, coil). One or more pre-treated copper materials can be electroplated simultaneously in the same electroplating electrolyte, and each pre-treated copper can be energized. In addition, multiple independent electroplating electrolyte containers can be used to electroplate copper. The result of electrolytic plating at 106 can be a nickel-plated copper sheet (e.g., a copper sheet or a copper alloy sheet plated with nickel or a nickel alloy), similar to Figure 2 Nickel plated copper blank 204 and / or Figure 3 306 of an unwound nickel-plated copper coil, wherein the shading indicates the nickel coating. Although method 100 describes electroplating nickel copper, other electroplating methods are also contemplated. For example, electroless plating may be included in a pre-braze plating method such as method 100, although electroless plating may have greater resource requirements and / or may not be as effective as electrolytic plating in a pre-braze plating method.

[0024] After electroplating, method 100 proceeds to step 108. If the initial unplated copper part is a copper coil (e.g. Figure 3 If the copper coil 302 in the embodiment of the present invention is completed and 102 is completed, the nickel-plated or nickel-alloy copper or copper alloy part can be rewound to form a rewound nickel-plated copper coil. In other words, if the starting uncoated copper part is a blank, a pre-stamped part, or other shapes other than a coil, 108 may not be completed. For example, Figure 3 The unwound copper coil 304 can be formed by electrolytic plating Figure 3 The unwound nickel-plated copper coil 306 is then rewound. The nickel-plated coil obtained after rewinding at 108 may be similar to Figure 3 The rewound nickel-plated copper coil 308 is similar to the rewound shape of the copper coil 302, wherein the rewound shape may be the same as the shape of the copper coil 302. Alternatively, the rewound shape may be different from the shape of the starting copper coil in at least one of the number of turns, length, width, diameter, and / or other coil dimensions, as described above with reference to Figure 3 As described above. Rewinding may facilitate the transportation of nickel-plated copper. In some examples, rewinding the copper coil at 108 may prepare the copper for shaping into a component in a subsequent step (such as stamping). In other examples, if the starting unplated copper sheet is a copper coil, rewinding may not be performed, depending on the stamping unit (such as Figure 4 Whether the configuration of the stamping unit 406 in can receive wound or unwound copper coils.

[0025] Next, method 100 proceeds to process 110, where electroplated copper stamping components can be optionally used. If the starting copper material includes pre-stamped CBHE components, method 100 may not include 110. However, if the starting copper material is not in the shape of a CBHE component (such as a coil and / or blank), it can be stamped from unprocessed nickel-plated copper (such as Figure 2 the nickel-plated copper blank 204 in Figure 3 or the rewound nickel-plated copper coil 308 in Figure 2 ) into the shape of a CBHE component (such as the stamped nickel-plated copper plate 206 in Figure 4 ). The CBHE assembly formed by stamping nickel-plated or nickel alloy copper or copper alloy parts may include a core plate, a bottom plate, heat transfer enhancement components (such as fins and turbines), etc. The stamping can include one or more steps to achieve the desired CBHE assembly shape and can involve one or more types of stamping, such as blanking, punching, perforating, bending, etc. The stamping can be completed by a stamping unit of a continuous assembly line, such as the stamping unit 406 of the assembly line 400 shown in

[0026] Figure 4 Figure 4 It can be a single stamping unit as shown, or multiple stamping units in series and / or parallel. For example, there can be one stamping unit for each CBHE part shape. Figure 4 the brazing unit 408 in the assembly line 400.

[0027] After assembly is completed, the components are bonded together by brazing to form a CBHE at 112. For example, referring to Figure 2, one or more stamping nickel-plated copper plates 206 can be laminated with one or more other stamping nickel-plated copper components to form a brazed plate heat exchanger 208. Other embodiments of method 100 may include brazing other types of CBHE components at 112 to form the desired heat exchanger component. Brazing may include applying high temperature to the nickel-plated stamping CBHE components by torch, furnace, induction, or other suitable heating methods, and applying filler metal to the desired joint areas of the heated components (such as stamping nickel-plated components). The filler metal can also be gaskets, wires, and / or pastes placed between the parts during and / or before heating. For example, when assembling at 111, gaskets can be placed between the parts. The filler metal can be a metal or metal alloy with a melting point lower than that of copper and nickel, such as copper-phosphorus alloy, copper-phosphorus-silver alloy, etc. The temperature can be lower than the melting point of copper and higher than the melting point of the filler metal. The filler metal can be placed between the heated parts so that the filler covers and diffuses into two or more nickel or nickel-alloy coatings to form a firm brazed joint. The filler metal can also form an alloy with the nickel coating in the area where the filler diffuses into the nickel coating. For example, a copper-alloy filler metal can form a copper-nickel alloy in the nickel coating. The formation of the alloy during brazing may be another feature distinguishing it from electroplating after brazing, which can be identified by metallographic examination and will be further discussed below with respect to Figure 7A and 7B . Brazing can be completed as an automatic and / or manual process in an assembly line, such as the brazing unit 408 of the assembly line 400 in Figure 4 . After brazing at 112, the nickel-plated CBHE (such as the nickel-plated CBHE 412 in Figure 4 ) has been assembled from brazed, stamping nickel-plated components by method 100, so method 100 ends. In certain embodiments of method 100, brazing is only performed after electroplating. In other words, brazing may not be performed before electroplating. In certain embodiments, method 100 may include other steps before 102 and / or after 112, which are not shown in the figure.

[0028] Figure 6 The brazed plate heat exchanger 600 shown is an embodiment of the CBHE produced by method 100. The brazed plate heat exchanger 600 is composed of multiple nickel-plated parts brazed together, including multiple plates 602 and inlet / outlet tubes 604. Brazed joints, such as the brazed joint 500 of the brazed plate heat exchanger 600, can exist at the connection points between two or more components of the CBHE formed by a pre-brazing nickel-plating method (such as the method 100 of Figure 1 ). The CBHE formed by brazed, stamping nickel-plated components by a pre-brazing nickel-plating method (such as the method 100 of Figure 1 ) can take various forms, including brazed plate heat exchangers (such as the brazed plate heat exchanger 600), shell-and-tube heat exchangers, etc.

[0029] Figure 5 shows an example of a brazed joint 500 formed between two pre-brazed electroplated and stamped components: a first copper component 502 with a first nickel coating 504 and a second copper component 506 with a second nickel coating 508. The coatings 504 and 508 can be in surface contact with the copper components 502 and 506 respectively. The coatings 504 and 508 can cover the outer surfaces of the copper elements 502 and 506 and conform to the shapes of the copper elements 502 and 506, thereby achieving a uniform nickel coating on each element. The thickness 524 of the first nickel coating 504 is substantially the same on the surface of the first copper component 502. Similarly, the thickness 528 of the second nickel coating 508 can also be substantially the same on the surface of the second copper component, thereby achieving a uniform nickel coating. In some examples, the thicknesses 524 and 528 of the first nickel coating 504 and the second nickel coating 508 can be in the range of 0.5 μm to 5 μm respectively. In some examples, the thickness 524 of the first nickel coating 504 can be the same as the thickness 528 of the second nickel coating 508. In another example, the thickness 524 of the first nickel coating 504 may be different from the thickness 528 of the second nickel coating 508. The filler 510 diffuses into the nickel coatings, including the first nickel coating 504 of the first copper component 502 and the second nickel coating 508 of the second copper component 506. The filler 510 can be a copper-phosphorus alloy, a copper-phosphorus-silver alloy, or other suitable filler metal. The filler 510 can diffuse through the full thickness of one or more nickel coatings (e.g., the thickness 524 of the first nickel coating 504 and the thickness 528 of the second nickel coating 508) at one or more points, so that the filler can reach the copper cores (e.g., the first copper core 512 and the second copper core 514). In addition, the filler 510 can also partially diffuse through the thickness of the nickel coatings (e.g., thickness 524 and thickness 528), so that there is solid nickel between the filler and the copper within the component. In the regions where the filler 510 diffuses into the first nickel coating 504 and the second nickel coating 508, an alloy may form between the nickel and the filler material. For example, when a copper alloy filler diffuses into the nickel layer, a copper-nickel alloy can be formed. In some examples, the filler can diffuse into two or more nickel layers of two or more brazed, stamped nickel-plated components. The relative orientations of the two or more brazed, stamped nickel-plated components can also be different from the orientations shown in the brazed joint 500, but the filler can diffuse into the corresponding nickel layers. The shapes of the brazed, stamped nickel-plated components can also be different from the first copper component 502 and the second copper component 506. In addition, relative proportions of copper, nickel, and filler metals different from those Figure 5 shown can be used.

[0030] Figure 7A and 7BSeparate example images 702 and 704 of the metallographic inspection of electroplated CBHE and CBHE before electroplating are shown. Specifically, images 702 and 704 show cross-sectional views, and by comparing these views, the differences in CBHE formed by post-plating brazing methods and pre-plating brazing methods can be shown. For example, similar images to images 702 and 704 can be taken by a scanning electron microscope (SEM), including X-ray energy dispersive spectroscopy (EDS), etc., in order to analyze the surface of CBHE and determine whether CBHE is nickel-plated before brazing (e.g., by Figure 1 method 100) or after brazing. Picture 702 shows the copper component 710 of the post-plated and brazed CBHE, with a nickel coating 706 and a filler 708 thereon, where the filler 708 can be used for brazing to bond two or more copper components (e.g., copper component 710). Picture 704 shows the copper component 720 of the pre-brazed and nickel-plated CBHE, with a nickel coating 716 and a filler 718 thereon, where the filler 718 can be used for brazing to bond two or more nickel-plated copper components (e.g., copper component 720 with nickel coating 716). In both of these figures, the filler 718 can be a copper alloy.

[0031] The pre-brazing and post-brazing of CBHE can be distinguished by the positions of the nickel layer and the filler layer. For example, in Figure 7A the post-brazed and electroplated CBHE in picture 702, the filler metal is in coplanar contact with the copper component 710, and the nickel layer 706 is in coplanar contact with the filler 708. In addition, at least a part of the nickel layer 706 and the copper component 710 is separated by the filler 708. In contrast, Figure 7B the pre-brazed and electroplated CBHE in picture 704 shows that the nickel coating 716 is in coplanar contact with the copper component 720. Therefore, the positions of the filler metal layer and the nickel plating layer relative to the copper component of the analyzed CBHE can indicate the type of method used to form CBHE (e.g., pre-brazed plating or post-brazed plating).

[0032] In addition, an identifiable element of pre-brazed electroplating is the formation of an alloy between the filler and the nickel coating in the pre-brazed electroplated CBHE (such as the pre-brazed electroplated CBHE in Figure 704). Specifically, during the brazing process (e.g., Figure 1In the brazing at method 100112, high temperatures may cause copper atoms and nickel atoms to diffuse and move towards each other from the filler 718 and the nickel coating 716 respectively, thereby forming a copper-nickel alloy, which can be traced by elemental mapping (such as SEM, EDS). In 704, the nickel coating 716 extends through the filler 718 to the surface 722 of the shown CBHE. Therefore, an alloy may have formed between the filler 718 and the nickel coating 716. In contrast, a CBHE electroplated after brazing (such as the CBHE electroplated after brazing shown in Figure 702) does not form an alloy between the filler 708 and the nickel coating 706 because nickel 706 does not exist at high temperatures during brazing, so there is no diffusion movement between the atoms of the filler 708 and the nickel coating 706. Therefore, heating during brazing may cause an alloy to form between the filler metal and the nickel coating in the pre-brazed electroplated CBHE, but not in the post-brazed electroplated CBHE. In other examples, an alloy may form between the nickel plating and other filler metals. In other words, the formation of the alloy is not limited to the copper-nickel alloy formed between the copper alloy filler metal and the nickel plating, as in Figure 7A and 7B the examples shown. In some examples, including Figure 7A and 7B the examples shown, elemental tracing shows the diffusion movement of atoms in the CBHE coating and filler to form an alloy, which may indicate that the CBHE is formed by a pre-brazing plating method.

[0033] The method disclosed herein can nickel-plate before brazing without brazing before nickel-plating, and its technical effect is to reduce the degradation of the brazed joint that occurs during the pretreatment of the post-brazing electroplating process, improve the efficiency of the nickel-plating process, and provide a more uniform nickel-plating coverage on the surface of the CBHE.

[0034] The present disclosure also provides support for a method that includes: pretreating a copper sheet, electroplating the nickel-coated copper sheet to form a nickel-coated copper sheet, after electroplating the nickel-coated copper sheet, stamping a component from the nickel-coated copper sheet to form a stamped nickel-coated component, and brazing the stamped nickel-coated component. In a first example of the method, brazing is performed only after nickel-plating the copper sheet. In a second example of the method, optionally including the first example, electroplating the nickel-coated copper sheet produces a nickel coating having a thickness in the range of 0.5 μm to 5 μm. In a third example of the method optionally including one or both of the first and second examples, brazing includes applying a filler metal, wherein the filler metal diffuses into two or more nickel coatings to form an alloy of the filler metal and the nickel coating. In a fourth example of the method, optionally including one or more or each of the first to third examples, brazing forms a heat exchanger. In a fifth example of the method, optionally including one or more or each of the first to fourth examples, brazing is not completed before electroplating.

[0035] The present disclosure also provides support for a method, which includes: electrolytically electroplating a copper or copper alloy sheet with nickel or a nickel alloy to form a nickel or nickel alloy electroplated copper or copper alloy sheet, wherein the electrolytic electroplating occurs before or after stamping the copper or copper alloy sheet; brazing the nickel or nickel alloy electroplated copper or copper alloy sheet, wherein the brazing forms a heat exchanger. In a first example of the method, the copper or copper alloy sheet is pretreated before electroplating. In a second example of the method, optionally including the first example, stamping is performed after electroplating and before brazing. In a third example of the method, optionally including one or both of the first and second examples, the thickness of the nickel coating after electroplating is between 0.5 μm and 5 μm. In a fourth example of the method, optionally including one or more or each of the first to third examples, the brazing includes applying a filler metal, wherein the filler metal diffuses into two or more nickel or nickel alloy coatings to form an alloy of the filler metal and the nickel or nickel alloy coatings. In a fifth example of the method, optionally including one or more or each of the first to fourth examples, the method further includes: unwinding the copper or copper alloy sheet before electroplating. In a sixth example of the method, optionally including one or more or each of the first to fifth examples, the brazing is performed only after electroplating. In a seventh example of the method (optionally including one or more or each of the first to sixth examples), brazing is not completed before electroplating.

[0036] The present disclosure also provides a bracket for a heat exchanger, including: a first copper component including a first nickel coating having a thickness in the range of 0.5 μm to 5 μm; a second copper component including a second nickel coating having a thickness in the range of 0.5 μm to 5 μm; a filler located between the first copper component and the second copper component, wherein the filler diffuses through the first nickel coating and the second nickel coating. In a first instance of the system, the filler is a copper-phosphorus alloy or a copper-phosphorus-silver alloy. In a second example of the system, optionally including the first example, the heat exchanger is formed by a method of pre-brazing nickel plating. In a third example of the system, optionally including one or both of the first and second examples, the first copper component and the second copper component are formed by stamping copper or a copper alloy plated with nickel or a nickel alloy. In a fourth example of the system, optionally including one or more or each of the first to third examples, an alloy is formed by the filler and one or more of the first nickel coating and the second nickel coating. In a fifth example of the system, optionally including one or more or each of the first to fourth examples, the first nickel coating is in coplanar contact with the first copper component, and the second nickel coating is in coplanar contact with the second copper component.

[0037] In another formulation, a method of forming a heat exchanger may include: pre-treating a copper blank, electroplating the nickel copper blank to form a nickel-plated copper blank, after electroplating the nickel copper blank, stamping parts from the nickel-plated copper blank to form a stamped nickel-plated part, and brazing the stamped nickel-plated part to form a brazed stamped nickel-plated part. In a first example of the method, brazing is performed only after nickel plating of the copper blank. In a second example of the method, optionally including the first example, electroplating the copper blank with nickel produces a nickel coating having a thickness in the range of 0.5 μm to 5 μm. In a third example of the method, optionally including one or both of the first and second examples, brazing includes applying a filler metal, wherein the filler metal diffuses into two or more nickel coatings to form an alloy of the filler metal and the nickel coatings. In a fourth example of the method, optionally including one or more or each of the first to third examples, the method further includes: forming a heat exchanger with the brazed, stamped nickel-plated parts. In a fifth example of the method, optionally including one or more or each of the first to fourth examples, brazing is not completed before electroplating.

[0038] In another formulation, a method of forming a heat exchanger may include: unwinding a copper coil to form an unwound copper coil, electroplating the unwound copper coil with nickel, and brazing parts of the nickel-plated copper coil. In a first example of the method, the copper coil is pre-treated before electroplating. In a second example of the method, optionally including the first example, the method further includes: stamping the nickel-plated copper coil after electroplating and before brazing. In a third example of the method, optionally including one or both of the first and second examples, electroplating the copper coil with nickel produces a nickel coating having a thickness in the range of 0.5 μm to 5 μm. In a fourth example of the method, optionally including one or more or each of the first to third examples, brazing includes applying a filler metal, wherein the filler metal diffuses into two or more nickel coatings to form an alloy of the filler metal and the nickel coatings. In a fifth example of the method, optionally including one or more or each of the first to fourth examples, brazing forms a heat exchanger. In a sixth example of the method, optionally including one or more or each of the first to fifth examples, brazing is performed only after electroplating. In a seventh example of the method, optionally including one or more or each of the first to sixth examples, brazing is not completed before electroplating. In an eighth example of the method, optionally including one or more of the first to seventh examples, the method further includes: rewinding the unwound nickel-plated copper coil after electrolytic electroplating.

[0039] In another representation, the heat exchanger may include: a first copper component including a first nickel coating with a thickness in the range of 0.5 μm to 5 μm; a second copper component including a second nickel coating with a thickness in the range of 0.5 μm to 5 μm; a filler located between the first copper component and the second copper component, wherein the filler diffuses through the first nickel coating and the second nickel coating. In a first example of the system, the filler is a copper-phosphorus alloy or a copper-phosphorus-silver alloy. In a second example of the system, optionally including the first example, the heat exchanger is formed by a method of pre-brazing nickel plating. In a third example of the system, optionally including one or both of the first example and the second example, the first copper component and the second copper component are formed by stamping nickel-plated copper. In a fourth example of the system, optionally including one or more or each of the first to third examples, an alloy is formed by the filler and one or more of the first nickel plating and the second nickel plating. In a fifth example of the system, optionally including one or more or each of the first to fourth examples, the first nickel plating is in coplanar contact with the first copper component, and the second nickel plating is in coplanar contact with the second copper component.

[0040] In another formulation, the method of forming a heat exchanger may include: pre-treating one or more unformed copper sheets; electroplating nickel on one or more copper sheets with a coating thickness between 0.5 μm and 5 μm; stamping a first part and a second part of the heat exchanger with one or more nickel-plated copper sheets; and brazing the first part of the heat exchanger to the second part of the heat exchanger.

[0041] Figure 5 and Figure 6Shows an example configuration of the relative positioning of various components. If the elements shown in the figure are in direct contact or directly coupled to each other, then in at least one example, these elements can be referred to as being in direct contact or directly coupled, respectively. Similarly, in at least one example, elements shown as contiguous or adjacent to each other can be contiguous or adjacent to each other, respectively. For example, elements in face-to-face contact with each other can be referred to as face-to-face contact elements. Another example is that in at least one example, elements are placed separately from each other, with only space in between and no other elements, and can be referred to as being placed separately from each other. Also, elements shown above / below each other, on opposite sides of each other, or on the left / right side of each other relative to each other can be referred to as such elements. In addition, as shown in the figure, in at least one example, the topmost element or element point can be referred to as the "top" of the element, and the bottommost element or element point can be referred to as the "bottom" of the element. The top / bottom, upper / lower, above / below used herein can be relative to the vertical axis in the figure and are used to describe the relative positioning of the elements in the figure with respect to each other. Thus, in one example, an element shown above other elements is vertically positioned above the other elements. For another example, the shapes of the elements depicted in the figure can be referred to as having these shapes (such as circular, straight, planar, curved, round, chamfered, beveled, or similar shapes). In addition, in one example, elements coaxial with each other can be referred to as coaxial elements. Further, in at least one example, elements shown as intersecting each other can be referred to as intersecting elements or intersecting with each other. Also, in one example, an element shown inside or outside another element can be referred to as an intersecting element. In other examples, elements that are offset from each other can also be referred to as "offset elements".

[0042] The following claims particularly point out certain combinations and sub-combinations that are regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or equivalent elements. These claims should be understood to include one or more such elements, neither requiring nor precluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or characteristics can be claimed by modifying these claims or by presenting new claims in this application or a related application. These claims, whether broader, narrower, the same, or different in scope from the original claims, are also regarded as being included in the subject matter of this disclosure.

Claims

1. A method, comprising pre-treating a copper sheet; electroplating nickel on the copper sheet to form a nickel-plated copper sheet; after electroplating nickel on the copper sheet, stamping a component with the nickel-plated copper sheet to form a stamped nickel-plated component; and brazing the stamped nickel-plated component.

2. The method according to claim 1, wherein brazing is performed only after nickel plating of the copper sheet.

3. The method according to claim 1, wherein electroplating nickel forms a nickel coating on the copper sheet, and the thickness of the nickel coating is between 0.5 micrometers and 5 micrometers.

4. The method according to claim 1, wherein brazing comprises using a filler metal that diffuses into two or more nickel coatings to form an alloy of the filler metal and the nickel coatings.

5. The method according to claim 4, wherein the filler metal is a copper-phosphorus alloy or a copper-phosphorus-silver alloy.

6. The method according to claim 1, wherein brazing is not completed before electroplating.

7. The method according to claim 1, further comprising unwinding a copper or copper alloy sheet before electroplating.

8. The method according to claim 1, wherein the pre-treatment comprises cleaning the copper sheet using a series of chemical cleaners and physical methods.

9. The method according to claim 1, wherein the brazing forms a heat exchanger.

10. A heat exchanger, comprising: a first copper component, the first copper component comprising a first nickel coating having a thickness in the range of 0.5 micrometers to 5 micrometers; a second copper component, the second copper component comprising a second nickel coating having a thickness in the range of 0.5 micrometers to 5 micrometers; a filler located between the first copper component and the second copper component, the filler diffusing through the first nickel coating and the second nickel coating.

11. The heat exchanger according to claim 10, wherein the filler is a copper-phosphorus alloy or a copper-phosphorus-silver alloy.

12. The heat exchanger according to claim 10, wherein the heat exchanger is formed by a method of pre-brazing nickel plating.

13. The heat exchanger according to claim 10, wherein the first copper component and the second copper component are stamped from copper or copper alloy plated with nickel or nickel alloy.

14. The heat exchanger according to claim 10, wherein the filler forms an alloy with one or more of the first nickel coating and the second nickel coating.

15. The heat exchanger according to claim 10, wherein the first nickel coating is in coplanar contact with the first copper component, and the second nickel coating is in coplanar contact with the second copper component.

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