Copper-aluminum laminated composite material and preparation method thereof, LED support

Abstract

This application relates to copper-aluminum layered composite materials and their preparation methods, as well as LED brackets. The copper-aluminum layered composite material of this application includes copper layers and aluminum layers; the copper and aluminum layers are stacked along the thickness direction of the copper-aluminum layered composite material; a copper-aluminum intermetallic compound layer is present between the copper and aluminum layers, the copper-aluminum intermetallic compound layer including multiple intermetallic compound sublayers spaced apart along a first direction, the first direction being the width direction of the copper-aluminum layered composite material; the thickness of the copper-aluminum intermetallic compound layer is 1 μm to 3 μm.

Description

Technical Field

[0001] This application relates to the field of composite materials technology, and in particular to copper-aluminum layered composite materials and their preparation methods, and LED brackets. Background Technology

[0002] Layered brass-aluminum-brass (Cu / Al / Cu) composites combine the excellent electrical and thermal conductivity, corrosion resistance, and weldability of copper with the lightweight and low-cost advantages of aluminum, making them widely used in electronics, lithium battery connectors, automotive wiring harnesses, and heat dissipation devices. The performance of composite materials hinges on the interface. The interfacial bonding of layered metal composites is essentially a solid-state diffusion metallurgical bond, a process accompanied by the formation of intermetallic compounds (IMCs). An appropriate thickness of IMC is necessary for achieving high-strength metallurgical bonding; however, excessively thick IMCs (typically 5μm~10μm) are brittle and become the initiation point for interfacial cracks, leading to a sharp drop in bond strength and brittle fracture at the interface.

[0003] Traditional technologies often focus on controlling interfacial reactions, such as suppressing IMC growth by lowering the composite temperature or shortening the high-temperature residence time. However, insufficient temperature or time leads to inadequate atomic diffusion, resulting in low bonding strength or even poor bonding; while slightly excessive temperature or time causes excessive IMC growth, leading to brittleness. In other words, traditional copper-aluminum layered composite materials struggle to achieve high interfacial bonding strength. Summary of the Invention

[0004] Therefore, it is necessary to provide a copper-aluminum layered composite material, its preparation method, and an LED bracket. The copper-aluminum layered composite material of this application has high interfacial bonding strength.

[0005] In a first aspect, this application provides a copper-aluminum layered composite material, comprising a copper layer and an aluminum layer; the copper layer and the aluminum layer are stacked along the thickness direction of the copper-aluminum layered composite material; a copper-aluminum intermetallic compound layer is provided between the copper layer and the aluminum layer, the copper-aluminum intermetallic compound layer comprising a plurality of intermetallic compound sublayers spaced apart along a first direction, the first direction being the width direction of the copper-aluminum layered composite material; the thickness of the copper-aluminum intermetallic compound layer is 1μm to 3μm.

[0006] In some embodiments, in the first direction, the total width of each of the intermetallic compound sublayers accounts for 10% to 60% of the width of the copper-aluminum layered composite material.

[0007] In some embodiments, each of the intermetallic compound sublayers has an independent width of less than 1 μm in the first direction.

[0008] In some embodiments, the distance between two adjacent intermetallic compound sublayers is 0.5 μm to 5 μm.

[0009] In some embodiments, the copper layer is two layers, with the two copper layers located on opposite sides of the aluminum layer.

[0010] In some embodiments, the interfacial shear strength of the copper-aluminum layered composite material is above 100 MPa.

[0011] In some embodiments, the conductivity of the copper-aluminum layered composite material is 85% to 90% of that of pure aluminum.

[0012] Secondly, this application provides a method for preparing a copper-aluminum layered composite material, comprising the following steps:

[0013] Multiple grooves are formed on the surface of a copper plate and / or an aluminum plate, and the multiple grooves are spaced apart along a first direction;

[0014] Copper plates and aluminum plates are stacked together, with the groove located between the copper plates and the aluminum plates;

[0015] A first rolling process is performed to form a copper layer and an aluminum layer, as well as a continuous copper-aluminum intermetallic compound layer located between the copper layer and the aluminum layer, to obtain a first composite plate.

[0016] The first composite plate is subjected to a second rolling process to break up the continuous copper-aluminum intermetallic compound layer, thereby obtaining a second composite plate.

[0017] The second composite material is subjected to heat treatment.

[0018] In some embodiments, the width of the groove along the first direction is 15 μm to 30 μm.

[0019] In some embodiments, the spacing between two adjacent grooves along the first direction is 30 μm to 100 μm.

[0020] In some embodiments, the depth of the trench is 8 μm to 12 μm.

[0021] In some embodiments, the temperature of the first rolling is 380°C to 420°C.

[0022] In some embodiments, the first rolling total reduction rate is 52% to 70%.

[0023] In some embodiments, the first rolling is a single pass.

[0024] In some embodiments, the first rolling is performed in a protective gas atmosphere.

[0025] In some embodiments, the temperature of the second rolling is 25°C to 200°C.

[0026] In some embodiments, the total reduction rate of the second rolling is 20% to 35%.

[0027] In some embodiments, the second rolling is multi-pass, with a reduction rate of 10% to 15% per pass.

[0028] In some embodiments, the heat treatment temperature is 180°C to 250°C.

[0029] In some embodiments, the heat treatment time is 0.5h to 2h.

[0030] In some embodiments, the process includes, prior to stacking the copper plate and the aluminum plate:

[0031] The surface of the aluminum plate forming the groove is roughened; and / or the surface of the aluminum plate forming the groove is plasma cleaned.

[0032] In some embodiments, the surface roughness Ra of the aluminum plate after the roughening treatment is 1 μm to 2 μm.

[0033] In some embodiments, the vacuum level of the plasma cleaning is 10 Pa to 30 Pa.

[0034] In some embodiments, the radio frequency power of the plasma cleaning is 300W~500W.

[0035] In some embodiments, the plasma cleaning time is 3 to 5 minutes.

[0036] Thirdly, this application provides an LED bracket comprising the copper-aluminum layered composite material described in any one of the above descriptions, or the copper-aluminum layered composite material prepared by the method described in any one of the above descriptions.

[0037] In the copper-aluminum layered composite material of this application embodiment, the thickness of the copper-aluminum intermetallic compound layer at the interface between the copper and aluminum layers is relatively thin, ranging from 1 μm to 3 μm, and exhibits a discontinuous, interlocking distribution at the interface, with the intermetallic compound dispersed at the interface. This avoids the continuity of the intermetallic compound, reduces the three-layer structure of copper-IMC-aluminum, and maintains a discontinuous two-layer structure of direct copper-aluminum bonding at the interface. Simultaneously, the discontinuous intermetallic compound also increases the specific surface area of ​​the intermetallic compound and the copper and aluminum matrices, further contributing to improved interfacial bonding strength.

[0038] Furthermore, compared to traditional copper-aluminum layered composite materials, the copper-aluminum layered composite material of this application can achieve high interfacial metallurgical bonding strength while effectively avoiding problems such as insufficient interfacial bonding force caused by excessively thick or brittle IMC layers, thereby giving the copper-aluminum layered composite material high reliability.

[0039] In the preparation method of the copper-aluminum layered composite material of this application embodiment, the first stage is "interface prefabrication". If the surfaces of both the copper plate and the aluminum plate are smooth planes, only a pressed rather than interlocked serrated interface can be formed after rolling. In this application, grooves are formed before rolling. During rolling, the softer aluminum will be squeezed into the grooves under high pressure, forming a preliminary mechanical interlock. The second stage is "cooperative rolling and dynamic crushing". In the first rolling, the copper and aluminum undergo intense plastic flow, and the aluminum fully fills the grooves to achieve macroscopic serrated interlock. At this time, due to deformation heat and frictional heat, the interface temperature will rise, which will inevitably trigger the nucleation and growth of the initial IMC, forming a continuous IMC layer. Before the IMC layer has fully grown and strengthened, a second rolling is performed. The plastic deformation of the metal matrix is ​​used to mechanically crush the continuous copper-aluminum intermetallic compound layer formed in the previous step into discontinuous fragments. At the same time, the continuous plastic flow will continuously expose new clean surfaces of copper and aluminum, allowing them to re-contact and bond between the IMC fragments. The third stage is "shaping and optimization." Although the interface after rolling has strong mechanical interlocking, atomic diffusion bonding is still insufficient. Heat treatment is needed to strengthen the metallurgical bond, allowing the dispersed IMC to bond better with the matrix and controlling its excessive growth. That is, the preparation method of the copper-aluminum layered composite material of this application can prepare a copper-aluminum layered composite material with discontinuous and relatively thin copper-aluminum intermetallic compound layers, and it has high interfacial bonding strength. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of a copper-aluminum layered composite material provided in one embodiment of this application;

[0041] Figure 2 This is a scanning electron microscope image of the copper-aluminum intermetallic compound layer at the interface in a traditional copper-aluminum layered composite material.

[0042] Figure 3 This is a scanning electron microscope image of the copper-aluminum intermetallic compound layer at the interface in another traditional copper-aluminum layered composite material.

[0043] Figure 4 A scanning electron microscope image of the copper-aluminum intermetallic compound layer at the interface in a copper-aluminum layered composite material provided in an embodiment of this application;

[0044] Figure 5A scanning electron microscope image of the copper-aluminum intermetallic compound layer at the interface in a copper-aluminum layered composite material provided in another embodiment of this application;

[0045] Figure 6 This is a scanning electron microscope (SEM) image of the copper-aluminum intermetallic compound layer at the interface in the copper-aluminum layered composite material obtained in Example 1 of this application.

[0046] Explanation of reference numerals in the attached figures:

[0047] 10-Copper layer; 20-Aluminum layer; 30-Copper-aluminum intermetallic compound layer; 31-Intermetallic compound sublayer. Detailed Implementation

[0048] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0050] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0053] Reference Figure 2 , Figure 3 As shown, Figure 2 , Figure 3 This is a scanning electron microscope (SEM) image of the copper-aluminum intermetallic compound layer 30 at the interface in a traditional copper-aluminum layered composite material. It can be seen that a continuous IMC layer forms between the traditional brass and aluminum, which is highly brittle, resulting in low interfacial bonding strength in the copper-aluminum layered composite material.

[0054] Based on this, refer to Figure 1 As shown, one embodiment of this application provides a copper-aluminum layered composite material, including a copper layer 10 and an aluminum layer 20, which are stacked along the thickness direction of the copper-aluminum layered composite material; a copper-aluminum intermetallic compound layer 30 is provided between the copper layer 10 and the aluminum layer 20, the copper-aluminum intermetallic compound layer 30 including a plurality of intermetallic compound sublayers 31 spaced apart along a first direction, the first direction being the width direction of the copper-aluminum layered composite material; the thickness of the copper-aluminum intermetallic compound layer 30 is 1μm~3μm.

[0055] In the copper-aluminum layered composite material of this application embodiment, the thickness of the copper-aluminum intermetallic compound layer 30 at the interface between the copper layer 10 and the aluminum layer 20 is relatively thin, ranging from 1 μm to 3 μm. If the thickness of the copper-aluminum intermetallic compound layer 30 is too thin, the metallurgical bonding strength is poor; if the thickness is too thick, it easily leads to a sharp drop in bonding strength and brittle fracture of the interface. Furthermore, the copper-aluminum intermetallic compound layer 30 exhibits a discontinuous, interlocking interface, with the intermetallic compound diffusely distributed at the interface. This avoids the continuity of the intermetallic compound, reduces the three-layer structure of copper-IMC-aluminum, and maintains a discontinuous two-layer structure of direct copper-aluminum bonding at the interface. Simultaneously, the discontinuous intermetallic compound also increases the specific surface area of ​​the intermetallic compound and the copper and aluminum matrices, further contributing to improved interfacial bonding strength.

[0056] Refer again Figure 1 As shown, exemplarily, Figure 1 The X-direction is the first direction. Figure 1The Y-direction refers to the thickness direction of the copper-aluminum layered composite material. Specifically, the thickness of the copper-aluminum intermetallic compound layer 30 refers to the fact that the thickness of each intermetallic compound sublayer 31 is within the range of 1 μm to 3 μm along the Y-direction. For example, Figure 1 In this context, 'c' represents the thickness of the intermetallic compound sublayer 31. Optionally, the thickness of the copper-aluminum intermetallic compound layer 30 can be 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, or 3 μm; alternatively, the thickness of the copper-aluminum intermetallic compound layer 30 can fall within any two of the aforementioned thicknesses. For example, refer to... Figure 4 , Figure 5 As shown, Figure 4 and Figure 5 The scanning electron microscope image of the copper-aluminum intermetallic compound layer 30 at the interface of the copper-aluminum layered composite material provided in an embodiment of this application shows that there is a copper-aluminum intermetallic compound layer 30 between the copper layer 10 and the aluminum layer 20. The copper-aluminum intermetallic compound layer 30 includes a plurality of intermetallic compound sublayers 31 spaced apart along a first direction, and the thickness of each intermetallic compound sublayer 31 is in the range of 1 μm to 3 μm.

[0057] Furthermore, compared to traditional copper-aluminum layered composite materials, the copper-aluminum layered composite material of this application can achieve high interfacial metallurgical bonding strength while effectively avoiding problems such as insufficient interfacial bonding force caused by excessively thick or brittle IMC layers, thereby giving the copper-aluminum layered composite material high reliability.

[0058] In some embodiments, the first direction is perpendicular to the width direction of the copper-aluminum layered composite material.

[0059] In some embodiments, in the first direction, the total width of each intermetallic compound sublayer 31 accounts for 10% to 60% of the width of the copper-aluminum layered composite material.

[0060] Within the range of the percentage of the total width of each intermetallic compound sublayer 31 to the width of the copper-aluminum layered composite material, it is easy to achieve a higher interfacial bonding strength of the copper-aluminum layered composite material. This avoids the copper-aluminum intermetallic compound layer 30 becoming too thick or too brittle due to the total width of each intermetallic compound sublayer 31 being too wide, or the mechanical interlocking force being insufficient due to the total width of each intermetallic compound sublayer 31 being too narrow.

[0061] Optionally, in the first direction, the percentage of the total width of each intermetallic compound sublayer 31 to the width of the copper-aluminum layered composite material is 10%, 20%, 30%, 40%, 50%, or 60%, or the percentage of the total width of each intermetallic compound sublayer 31 to the width of the copper-aluminum layered composite material may be within the range of any two of the above percentages.

[0062] In some embodiments, each intermetallic compound sublayer 31 has an independent width of less than 1 μm in the first direction.

[0063] Refer again Figure 1 As shown, exemplarily, Figure 1 In the first direction, 'a' represents the individual width of each intermetallic compound sublayer 31. Within the range of the individual widths of each intermetallic compound sublayer 31 in the first direction, it is convenient to achieve a higher interfacial bonding strength of the copper-aluminum layered composite material. This avoids the copper-aluminum intermetallic compound layer 30 becoming too thick or too brittle due to excessively wide individual widths of each intermetallic compound sublayer 31 in the first direction, or the mechanical interlocking force becoming insufficient due to excessively narrow individual widths of each intermetallic compound sublayer 31 in the first direction.

[0064] Optionally, the width of each intermetallic compound sublayer 31 in the first direction is 0.01 μm to 1 μm. More preferably, the width of each intermetallic compound sublayer 31 in the first direction is 0.01 μm, 0.02 μm, 0.05 μm, 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm or 1 μm. Alternatively, the width of each intermetallic compound sublayer 31 in the first direction may be within the range of any two of the above widths.

[0065] In some embodiments, the distance between two adjacent intermetallic compound sublayers 31 is 0.5 μm to 5 μm.

[0066] Refer again Figure 1 As shown, exemplarily, Figure 1 In this context, 'b' represents the distance between two adjacent intermetallic compound sublayers 31. Within the range of the distance between the two adjacent intermetallic compound sublayers 31, it is easier to achieve a higher interfacial bonding strength in the copper-aluminum layered composite material, and it can avoid the copper-aluminum intermetallic compound layer 30 becoming too thick or too brittle due to the distance between the two adjacent intermetallic compound sublayers 31 being too wide or too narrow.

[0067] Optionally, the distance between two adjacent intermetallic compound sublayers 31 can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, or the distance between two adjacent intermetallic compound sublayers 31 can be within any of the above two distances.

[0068] In some embodiments, the copper layer 10 consists of two layers, with the two copper layers 10 located on opposite sides of the aluminum layer 20.

[0069] In some embodiments, the material of the copper layer 10 includes at least one of brass and copper.

[0070] In some embodiments, the interfacial shear strength of the copper-aluminum layered composite material is above 100 MPa.

[0071] Traditional copper-aluminum layered composites typically exhibit interfacial shear strengths of 60 MPa to 70 MPa, while the copper-aluminum layered composite of this application demonstrates significantly improved interfacial shear strength. Optionally, the interfacial shear strength of the copper-aluminum layered composite is 100 MPa to 140 MPa. More preferably, the interfacial shear strength of the copper-aluminum layered composite is 120 MPa to 140 MPa. Further preferably, the interfacial shear strength of the copper-aluminum layered composite is 120 MPa, 122 MPa, 124 MPa, 126 MPa, 128 MPa, 130 MPa, 132 MPa, 134 MPa, 136 MPa, 138 MPa, or 140 MPa; alternatively, the interfacial shear strength of the copper-aluminum layered composite can fall within the range of any two of the aforementioned shear strengths.

[0072] In this application, the interfacial shear strength test is performed in accordance with the shear strength sample preparation requirements and test methods in GB / T 32468-2025 "Copper-Aluminum Composite Plates, Strips and Foils".

[0073] It should be noted that the shear strength test requires a copper-aluminum layered composite material with a thickness of not less than 0.6 mm. Since copper-aluminum layered composite materials with a thickness less than 0.6 mm are difficult to test for shear strength, a method is used to determine the strength by ensuring no delamination after multiple bending fractures. The copper-aluminum layered composite material of this application embodiment can achieve a durability of ≥8 cycles, and the copper and aluminum do not delaminate after fracture, meaning the interfacial strength of the copper-aluminum layered composite material is greater than the strength of a single layer of material itself.

[0074] In some embodiments, the conductivity of the copper-aluminum layered composite material is 85% to 90% of that of pure aluminum.

[0075] Optionally, the conductivity of the copper-aluminum layered composite material is 85%, 86%, 87%, 88%, 89%, or 90% of the conductivity of pure aluminum, or the percentage of the conductivity of the copper-aluminum layered composite material to the conductivity of pure aluminum can be within any two of the above percentages.

[0076] In some embodiments, the conductivity of the copper-aluminum layered composite material is 55% IACS to 60% IACS.

[0077] Optionally, the conductivity of the copper-aluminum layered composite material is 55% IACS, 56% IACS, 57% IACS, 58% IACS, 59% IACS or 60% IACS, or the conductivity of the copper-aluminum layered composite material can be within the range of any two of the above conductivity values.

[0078] Another embodiment of this application provides a method for preparing a copper-aluminum layered composite material, comprising the following steps:

[0079] Multiple grooves are formed on the surface of a copper plate and / or an aluminum plate, and the multiple grooves are spaced apart along a first direction;

[0080] The copper and aluminum plates are stacked together so that the groove is located between the copper and aluminum plates;

[0081] A first rolling process is performed to form a copper layer 10 and an aluminum layer 20, as well as a continuous copper-aluminum intermetallic compound layer 30 located between the copper layer 10 and the aluminum layer 20, to obtain a first composite plate.

[0082] The first composite plate is subjected to a second rolling process to break up the continuous copper-aluminum intermetallic compound layer 30, thereby obtaining the second composite plate.

[0083] The second composite material is heat-treated.

[0084] In the preparation method of the copper-aluminum layered composite material of this application embodiment, the first stage is "interface prefabrication". If the surfaces of the copper plate and the aluminum plate are both smooth planes, only a pressed rather than interlocked serrated interface can be formed after rolling. In this application, grooves are formed before rolling. During rolling, the softer aluminum will be squeezed into the grooves under high pressure, forming a preliminary mechanical interlock. The second stage is "cooperative rolling and dynamic crushing". In the first rolling, the copper and aluminum undergo intense plastic flow, and the aluminum fully fills the grooves to achieve macroscopic serrated interlock. At this time, due to deformation heat and frictional heat, the interface temperature will rise, which will inevitably trigger the nucleation and growth of the initial IMC, forming a continuous IMC layer. Before the IMC layer has fully grown and strengthened, a second rolling is performed. Using the plastic deformation of the metal matrix, the continuous copper-aluminum intermetallic compound layer 30 formed in the previous step is mechanically crushed into discontinuous fragments. At the same time, the continuous plastic flow will continuously expose new clean surfaces of copper and aluminum, allowing them to re-contact and bond between the IMC fragments. The third stage is "shaping and optimization." Although the interface after rolling has strong mechanical interlocking, atomic diffusion bonding is still insufficient. Heat treatment is needed to strengthen the metallurgical bond, allowing the dispersed IMC to bond better with the matrix and controlling its excessive growth. That is, the preparation method of the copper-aluminum layered composite material of this application can prepare a copper-aluminum layered composite material with discontinuous and relatively thin copper-aluminum intermetallic compound layers 30, and it has high interfacial bonding strength.

[0085] In some embodiments, the width of the groove along the first direction is 15 μm to 30 μm.

[0086] Optionally, along the first direction, the width of the trench is 15μm, 18μm, 20μm, 22μm, 25μm, 28μm or 30μm, or the width of the trench may be within the range of any two of the above widths.

[0087] In some embodiments, the spacing between two adjacent trenches along the first direction is 30 μm to 100 μm.

[0088] Optionally, along the first direction, the spacing between two adjacent grooves is 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, or the spacing between two adjacent grooves may be within any of the above two widths.

[0089] In some embodiments, the depth of the trench is 8 μm to 12 μm.

[0090] Optionally, the depth of the trench is 8 μm, 9 μm, 10 μm, 11 μm or 12 μm, or the depth of the trench may be within any two of the above depths.

[0091] Within the range of parameters for each of the above-mentioned grooves, it is easy to achieve a good mechanical interlocking effect between the aluminum plate and the copper plate. At the same time, it is also easy to obtain the intermetallic compound sublayer 31 with appropriate size and distribution, thereby achieving a good interfacial bonding strength of the copper-aluminum layered composite material.

[0092] In some embodiments, the temperature of the first rolling is 380°C to 420°C.

[0093] Optionally, the temperature of the first rolling process is 380°C, 385°C, 390°C, 395°C, 400°C, 405°C, 410°C, 415°C, or 420°C, or the temperature of the first rolling process may be within the range of any two of the above temperatures.

[0094] In some embodiments, the first rolling total reduction rate is 52% to 70%.

[0095] It is understood that the reduction rate refers to the amount of thickness reduction before and after rolling. For example, if the thickness before rolling is M1 and the thickness after rolling is M2, the reduction rate is (M1-M2) / M1. Optionally, the first total rolling reduction rate is 52%, 55%, 58%, 60%, 62%, 65%, 68%, or 70%, or the first total rolling reduction rate may be within the range of any two of the above reduction rates.

[0096] In some implementations, the first rolling is a single pass.

[0097] In some embodiments, the first rolling is performed in a protective gas atmosphere.

[0098] Through the first rolling process, under the combined action of heat and force, preliminary metallurgical bonding of the matrix is ​​achieved, and an initial IMC layer with controllable thickness, continuous and complete, is intentionally generated. The temperature of the first rolling is a critical technical window. If the temperature of the first rolling is too low, IMC formation is too slow and the bonding is weak. If the temperature of the first rolling is too high, IMC growth is too rapid and the aluminum material softens severely. The total reduction rate of the first rolling is 52%~70%. Within this range, sufficient plastic deformation can be ensured to allow the fresh metal at the interface to fully contact and diffuse. The first rolling is carried out in a protective gas atmosphere to minimize interface oxidation. In this stage, brass and aluminum are tightly bonded under high pressure, and high temperature drives the rapid interdiffusion of Cu, Al, and Zn atoms, forming a continuous IMC layer at the interface. This layer is the raw material for subsequent crushing operations.

[0099] In some embodiments, the temperature of the second rolling is 25°C to 200°C.

[0100] Optionally, the temperature of the second rolling is 100℃~200℃. More preferably, the temperature of the second rolling is 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃, or the temperature of the second rolling can be within the range of any two of the above temperatures.

[0101] In some embodiments, the total reduction rate of the second rolling is 20% to 35%.

[0102] Optionally, the total reduction rate of the second rolling is 20%, 22%, 25%, 28%, 30%, 32%, or 35%, or the total reduction rate of the second rolling can be within the range of any two of the above reduction rates.

[0103] In some embodiments, the second rolling is performed in multiple passes, with a reduction rate of 10% to 15% per pass.

[0104] Optionally, the reduction rate per pass may be 10%, 11%, 12%, 13%, 14% or 15%, or the reduction rate per pass may be within the range of any two of the above reduction rates.

[0105] The second rolling process performs secondary deformation on the first composite sheet with a continuous IMC layer. Utilizing the shear force generated by the plastic deformation of the matrix, the continuous brittle IMC layer is "shredded," while simultaneously promoting the formation of three-dimensional interlocking within the matrix. The second rolling can be cold rolling or warm rolling, with a rolling temperature of 25℃~200℃, preferably 100℃~200℃. At this temperature, IMC growth is almost nonexistent (kinetics are extremely slow), and brass and aluminum retain good plasticity, with a more pronounced difference in yield strength, which is beneficial for applying shear stress to the IMC layer. If the total reduction rate of the second rolling is too small, it is difficult to break up the IMC; if the total reduction rate is too large, it may lead to excessive overall work hardening of the material or loss of sheet shape control. The second rolling can be performed in a single pass or multiple passes, preferably with a small reduction rate and multiple passes, to achieve IMC breakage and interface reconstruction more gently and uniformly. When the first composite sheet passes through the rolls again, the brass and aluminum matrix undergo coordinated plastic deformation. Because the IMC layer is brittle and cannot coordinate deformation, enormous shear stress is generated between the matrix and the IMC layer, as well as within the IMC layer itself. This causes the continuous IMC layer to fracture and fragment into particles of varying sizes. Simultaneously, the flow of the matrix metal is squeezed out from the gaps in the fractured IMC, allowing the fresh brass and aluminum in the underlying layer to come into direct contact, forming new metallurgical bonding points with little or no IMC. This reduces the three-layer structure while maintaining a direct brass-aluminum bond. Due to the slight unevenness of the initial bonding interface and the stress concentration at the IMC fracture points, the plastic flow of the matrix metal is not completely uniform, resulting in a wavy or serrated interlocking interface at the microscopic level. The IMC particles are then encased or embedded in the troughs or localized areas of these interlocking structures.

[0106] In some embodiments, the heat treatment temperature is 180°C to 250°C.

[0107] Optionally, the heat treatment temperature is 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C, or the heat treatment temperature may be within any two of the above temperatures.

[0108] In some embodiments, the heat treatment time is 0.5h to 2h.

[0109] Optionally, the heat treatment time is 0.5h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2h, or the heat treatment time can be within any two of the above times.

[0110] Heat treatment can release the processing stress generated by the preceding rolling, allowing the dispersed IMC particles to form a more robust bond with the matrix, while preventing excessive growth and re-attachment of the IMC particles. Heat treatment can be performed in air or a protective atmosphere, at which oxidation is controllable. At lower temperatures, atoms undergo only short-range diffusion, sufficient to relax interfacial stress and improve the wettability of IMC particles to the matrix, but far from enough to significantly coarsen or bond the IMC particles.

[0111] In some embodiments, the following steps are included before the copper and aluminum plates are stacked:

[0112] Roughening treatment is applied to the surface of the aluminum plate where the grooves are formed; and / or, plasma cleaning is performed on the surface of the aluminum plate where the grooves are formed.

[0113] Roughening treatment can increase the actual surface area of ​​the aluminum plate, providing more bonding points, while plasma cleaning can remove the inert aluminum oxide film, obtaining an atomically clean and highly active aluminum surface, thereby improving the bonding strength.

[0114] In some implementations, roughening is achieved by sandblasting.

[0115] In some embodiments, the surface roughness Ra of the aluminum plate after roughening treatment is 1 μm to 2 μm.

[0116] Optionally, the surface roughness Ra of the aluminum plate after roughening treatment is 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm or 2 μm, or the surface roughness Ra of the aluminum plate after roughening treatment can be within the range of any two of the above roughnesses.

[0117] In some embodiments, the vacuum level of plasma cleaning is 10 Pa to 30 Pa.

[0118] Optionally, the vacuum degree of plasma cleaning is 10 Pa, 12 Pa, 15 Pa, 18 Pa, 20 Pa, 22 Pa, 25 Pa, 28 Pa or 30 Pa, or the vacuum degree of plasma cleaning can be within the range of any two of the above vacuum degrees.

[0119] In some embodiments, the radio frequency power of plasma cleaning is 300W~500W.

[0120] Optionally, the radio frequency power of plasma cleaning is 300W, 320W, 350W, 380W, 400W, 420W, 450W, 480W or 500W, or the radio frequency power of plasma cleaning can be within the range of any two of the above radio frequency powers.

[0121] In some embodiments, the plasma cleaning time is 3 to 5 minutes.

[0122] Optionally, the plasma cleaning time is 3 min, 3.2 min, 3.5 min, 3.8 min, 4 min, 4.2 min, 4.5 min, 4.8 min or 5 min, or the plasma cleaning time can be within any two of the above times.

[0123] Furthermore, this application achieves the following beneficial effects through the above-described method for preparing copper-aluminum layered composite materials:

[0124] (1) By adopting the strategy of “physical and mechanical combination first, followed by metallurgical strengthening”, the interface bonding strength is significantly improved, and repeated bending does not cause delamination, thus solving the core contradiction that it is difficult to achieve both high strength and thin IMC layer.

[0125] (2) The thickness of the IMC layer was successfully and precisely controlled within the ideal range of 1μm to 3μm, and a gradient structure was formed. That is, this application does not simply reduce the IMC, but optimizes the IMC to minimize its harmfulness and utilizes it to strengthen the interface.

[0126] (3) The low-temperature pre-composite step reduces the dependence on high temperature, and the subsequent heat treatment parameters can be precisely programmed and controlled. This makes the process more tolerant of fluctuations in the preceding process and equipment conditions, and the batch consistency of the products is far superior to that of traditional methods.

[0127] (4) Due to the low main composite temperature, the work hardening of the aluminum core is eliminated, and its plasticity, electrical conductivity and thermal conductivity are better preserved. At the same time, the ultra-strong interface ensures the high reliability of the composite material in subsequent processing and use.

[0128] Specifically, regarding the structure, this application optimizes the harmful flat interface and continuously brittle IMC layer structure produced by traditional processes into a composite structure consisting of a three-dimensional wavy mechanically interlocked skeleton, a dispersed IMC strengthening phase, and a localized direct metallurgical bonding zone. The IMC transforms from a source of crack initiation and propagation into a beneficial second phase that pins and strengthens the interface. The interface is upgraded from a single, brittle metallurgical bond to a multi-functional synergistic mechanism involving mechanical anchoring, dispersion strengthening, and metallurgical bonding.

[0129] Specifically, in terms of performance, the core properties are no delamination after multiple bends and high bonding strength, which can reduce the problem of delamination of composite materials in subsequent cold working processes such as stamping and bending; while achieving interface toughness, the conductivity is maintained at more than 85% of the theoretical value of pure aluminum, ensuring that the core electrical function is not compromised.

[0130] Another embodiment of this application provides an LED bracket comprising the copper-aluminum layered composite material of any one of the above-mentioned methods, or the copper-aluminum layered composite material prepared by the preparation method of the copper-aluminum layered composite material of any one of the above-mentioned methods.

[0131] The following are specific embodiments.

[0132] Example 1

[0133] Materials: H65 brass, 2.0mm thick; 3003 aluminum alloy, 3.0mm thick. The total thickness of the target composite board is approximately 2.0mm (brass / aluminum / brass ≈ 0.5 / 1.0 / 0.5mm).

[0134] Preparation method of copper-aluminum layered composite material:

[0135] (1) Pretreatment: All plates are pickled, cleaned with alcohol, and dried. Periodic parallel trench arrays are processed on the copper plate to be laminated. Equipment selection: High beam quality fiber laser. Processing parameters: Trench depth: 10μm; Trench width: 20μm; Trench spacing: 50μm. Laser wavelength: 1064nm or 532nm. Laser average power: 18-20W; Pulse frequency: 80-100kHz; Scanning speed: 800-1000mm / s; Number of scans: 3-4. Assist gas: Coaxial or side-blown compressed air or nitrogen, used to remove slag in time and ensure the inner wall of the trench is smooth. Posttreatment: Ultrasonic cleaning with water-based cleaning agent is performed immediately after processing for 2-5 minutes to remove slag, dust, particles, etc.

[0136] (2) First rolling: The two layers of brass coils and the middle layer of aluminum coil are uncoiled and rolled together. The mixture is heated to 400°C in a nitrogen-protected atmosphere furnace and held for 30 minutes. Single-pass hot rolling is performed at 400°C with a total reduction of 70%. The mixture is then air-cooled. Metallographic observation of the sample reveals a continuous, uniform IMC layer with a thickness of approximately 2.5 μm at the interface.

[0137] (3) Second rolling: The above material is reheated to 150°C for warm rolling. Two passes are performed at 150°C: the first pass has a reduction of 15%, and the second pass has a reduction of 12%. The total reduction is about 25%. After rolling, the material is air-cooled to room temperature.

[0138] (4) Heat treatment: Place the billet in an air furnace at 220℃ and keep it at that temperature for 1 hour, then air cool it.

[0139] Final product analysis and performance:

[0140] Reference Figure 6As shown, the interface microstructure (SEM) reveals a distinct wavy undulation. The continuous IMC layer has disappeared, replaced by granular IMC dispersed throughout the interface, primarily concentrated at the troughs. Interface shear strength: tested according to GB / T6396 standard, with an average value of 138 MPa.

[0141] Bending performance: When bent 180 degrees along the direction perpendicular to the interface (R=2t), there is no delamination at the interface.

[0142] Conductivity: The overall conductivity of the composite material is approximately 86% of that of pure aluminum.

[0143] Example 2

[0144] The preparation method of the copper-aluminum layered composite material in Example 2 is basically the same as that in Example 1, except that H65 brass is replaced with T2 copper.

[0145] Final product analysis and performance:

[0146] The continuous IMC layer has disappeared, replaced by granular IMC dispersed at the interface, mainly concentrated in the troughs. Interfacial shear strength: tested according to GB / T6396 standard, with an average value of 140 MPa.

[0147] Bending performance: When bent 180 degrees along the direction perpendicular to the interface (R=2t), there is no delamination at the interface.

[0148] Conductivity: The overall conductivity of the composite material is approximately 90% of that of pure aluminum.

[0149] Example 3

[0150] The preparation method of the copper-aluminum layered composite material in Example 3 is basically the same as that in Example 1. The only difference is that in step (2), the first rolling is performed by uncoiling and rolling two layers of brass coils and an intermediate layer of aluminum coil into a composite. The mixture is heated to 420°C in a nitrogen-protected atmosphere furnace and held for 30 minutes. Single-pass hot rolling is performed at 420°C with a total reduction rate of 60%. The mixture is then air-cooled. Metallographic observation of the sample shows that a continuous, uniform IMC layer with a thickness of about 2.8 μm exists at the interface.

[0151] Final product analysis and performance:

[0152] The continuous IMC layer has disappeared, replaced by granular IMC dispersed at the interface, mainly concentrated in the troughs. Interfacial shear strength: tested according to GB / T6396 standard, the average value is 132 MPa.

[0153] Bending performance: When bent 180 degrees along the direction perpendicular to the interface (R=2t), there is no delamination at the interface.

[0154] Conductivity: The overall conductivity of the composite material is approximately 86% of that of pure aluminum.

[0155] Example 4

[0156] The preparation method of the copper-aluminum layered composite material in Example 4 is basically the same as that in Example 1, except that in step (2), the first rolling process involves uncoiling and rolling two layers of brass coils and an intermediate layer of aluminum coil into a composite. The mixture is heated to 380°C in a nitrogen-protected atmosphere furnace and held for 40 minutes. A single-pass hot rolling process is then performed at 380°C with a total reduction rate of 55%. The mixture is then air-cooled. Metallographic observation of the sample reveals a continuous, uniform IMC layer with a thickness of approximately 3 μm at the interface.

[0157] Final product analysis and performance:

[0158] The continuous IMC layer has disappeared, replaced by granular IMC dispersed at the interface, mainly concentrated in the troughs. Interfacial shear strength: tested according to GB / T6396 standard, with an average value of 130 MPa.

[0159] Bending performance: When bent 180 degrees along the direction perpendicular to the interface (R=2t), there is no delamination at the interface.

[0160] Conductivity: The overall conductivity of the composite material is approximately 85% of that of pure aluminum.

[0161] Example 5

[0162] The preparation method of the copper-aluminum layered composite material in Example 5 is basically the same as that in Example 1, except that in step (3), the second rolling is performed by reheating the material to 80°C for warm rolling. Three passes are performed at 80°C: the first pass has a reduction rate of 12%, the second pass has a reduction rate of 10%, and the third pass has a reduction rate of 10%. The total reduction rate is approximately 29%. After rolling, the material is air-cooled to room temperature.

[0163] Final product analysis and performance:

[0164] The continuous IMC layer has disappeared, replaced by granular IMC dispersed at the interface, mainly concentrated in the troughs. Interfacial shear strength: tested according to GB / T6396 standard, the average value is 136 MPa.

[0165] Bending performance: When bent 180 degrees along the direction perpendicular to the interface (R=2t), there is no delamination at the interface.

[0166] Conductivity: The overall conductivity of the composite material is approximately 87% of that of pure aluminum.

[0167] Comparative Example 1

[0168] The materials used in Comparative Example 1 are the same as those used in Example 1.

[0169] Preparation method of copper-aluminum layered composite material:

[0170] In Comparative Example 1, hot rolling was performed directly at 500℃ in a single pass, with a total reduction rate of 70%. After rolling, the material was directly air-cooled without subsequent warm rolling or special heat treatment.

[0171] Results analysis:

[0172] Interface microstructure (SEM): The interface is relatively flat. There is a continuous IMC layer with a thickness of about 8-12 μm, with local microcracks.

[0173] Interfacial shear strength: Tested according to GB / T6396 standard, the average value is 62MPa.

[0174] Bending performance: When bent at 90 degrees, obvious macroscopic cracks and delamination appear at the interface.

[0175] Comparative Example 2

[0176] The materials used in Comparative Example 2 were the same as those used in Example 1.

[0177] Preparation method of copper-aluminum layered composite material:

[0178] Step (3) is omitted in Comparative Example 2.

[0179] Results analysis:

[0180] Interface microstructure: The IMC layer remains continuous, and after annealing it thickens slightly to about 3.5 μm, but it is still a continuous layer.

[0181] Interfacial shear strength: Tested according to GB / T6396 standard, the average value is 68MPa.

[0182] Bending performance: When bent at 180 degrees, obvious macroscopic cracks and delamination appear at the interface.

[0183] Comparative Example 3

[0184] The materials used in Comparative Example 3 were the same as those used in Example 1.

[0185] Preparation method of copper-aluminum layered composite material:

[0186] Step (1) is omitted in Comparative Example 3.

[0187] Results analysis:

[0188] Interface microstructure (SEM): The interface is relatively flat. There is a continuous IMC layer with a thickness of about 6-10 μm, with local microcracks.

[0189] Interfacial shear strength: Tested according to GB / T6396 standard, the average value is 60MPa.

[0190] Bending performance: When bent at 90 degrees, obvious macroscopic cracks and delamination appear at the interface.

[0191] Comparative Example 4

[0192] The materials used in Comparative Example 4 were the same as those used in Example 1.

[0193] Preparation method of copper-aluminum layered composite material:

[0194] The preparation method of the copper-aluminum layered composite material in Comparative Example 4 is basically the same as that in Example 1, except that in step (2), the first rolling process involves uncoiling and rolling two layers of brass coils and an intermediate layer of aluminum coil into a composite. The mixture is heated to 200°C in a nitrogen-protected atmosphere furnace and held for 5 minutes. Single-pass hot rolling is performed at 200°C with a total reduction rate of 70%. The mixture is then air-cooled after rolling.

[0195] Results analysis:

[0196] It is difficult to form a suitable IMC layer, and the bonding strength is too low.

[0197] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0198] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A copper-aluminum layered composite material, comprising a copper layer and an aluminum layer; the copper layer and the aluminum layer are stacked along the thickness direction of the copper-aluminum layered composite material; a copper-aluminum intermetallic compound layer is provided between the copper layer and the aluminum layer, the copper-aluminum intermetallic compound layer comprising a plurality of intermetallic compound sublayers spaced apart along a first direction, the first direction being the width direction of the copper-aluminum layered composite material; the thickness of the copper-aluminum intermetallic compound layer is 1 μm to 3 μm.

2. The copper-aluminum layered composite of claim 1, wherein, In the first direction, the total width of each of the intermetallic compound sublayers accounts for 10% to 60% of the width of the copper-aluminum layered composite material.

3. The copper-aluminum layered composite material according to any one of claims 1 to 2, wherein, Each of the intermetallic compound sublayers has an independent width of less than 1 μm in the first direction.

4. The copper-aluminum layered composite material according to any one of claims 1 to 3, wherein, The distance between two adjacent intermetallic compound sublayers is 0.5 μm to 5 μm.

5. The copper-aluminum layered composite material according to any one of claims 1 to 4, wherein, The copper layer consists of two layers, which are located on opposite sides of the aluminum layer.

6. The copper-aluminum layered composite material according to any one of claims 1 to 5, wherein, The interfacial shear strength of the copper-aluminum layered composite material is above 100 MPa.

7. The copper-aluminum layered composite material according to any one of claims 1 to 6, wherein, The conductivity of the copper-aluminum layered composite material is 85% to 90% of that of pure aluminum.

8. A method for preparing a copper-aluminum layered composite material, comprising the following steps: Multiple grooves are formed on the surface of a copper plate and / or an aluminum plate, and the multiple grooves are spaced apart along a first direction; Copper plates and aluminum plates are stacked together, with the groove located between the copper plates and the aluminum plates; A first rolling process is performed to form a copper layer and an aluminum layer, as well as a continuous copper-aluminum intermetallic compound layer located between the copper layer and the aluminum layer, to obtain a first composite plate. The first composite plate is subjected to a second rolling process to break up the continuous copper-aluminum intermetallic compound layer, thereby obtaining a second composite plate. The second composite material is subjected to heat treatment.

9. The method for preparing the copper-aluminum layered composite material according to claim 8, wherein, Along the first direction, the width of the groove is 15μm~30μm.

10. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 9, wherein, Along the first direction, the spacing between two adjacent grooves is 30μm to 100μm.

11. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 10, wherein, The depth of the trench is 8μm~12μm.

12. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 11, wherein, The temperature of the first rolling process is 380℃~420℃.

13. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 12, wherein, The total reduction rate of the first rolling process is 52% to 70%.

14. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 13, wherein, The first rolling process is a single pass.

15. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 14, wherein, The first rolling process is carried out in a protective gas atmosphere.

16. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 15, wherein, The second rolling temperature is 25℃~200℃.

17. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 16, wherein, The total reduction rate of the second rolling process is 20% to 35%.

18. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 17, wherein, The second rolling process is multi-pass, with a reduction rate of 10% to 15% per pass.

19. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 18, wherein, The heat treatment temperature is 180℃~250℃.

20. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 19, wherein, The heat treatment time is 0.5h to 2h.

21. The method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 20, wherein, Before stacking the copper plate and the aluminum plate, the following steps are also included: The surface of the aluminum plate forming the groove is roughened; and / or the surface of the aluminum plate forming the groove is plasma cleaned.

22. The method for preparing the copper-aluminum layered composite material according to claim 21, wherein, The surface roughness Ra of the aluminum plate after the roughening treatment is 1μm~2μm.

23. The method for preparing the copper-aluminum layered composite material according to any one of claims 21-22, wherein, The vacuum level of the plasma cleaning is 10 Pa to 30 Pa.

24. The method for preparing the copper-aluminum layered composite material according to any one of claims 21 to 23, wherein, The radio frequency power of the plasma cleaning is 300W~500W.

25. The method for preparing the copper-aluminum layered composite material according to any one of claims 21 to 24, wherein, The plasma cleaning time is 3 to 5 minutes.

26. An LED bracket comprising a copper-aluminum layered composite material according to any one of claims 1 to 7, or a copper-aluminum layered composite material prepared by the method for preparing the copper-aluminum layered composite material according to any one of claims 8 to 25.

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