Composite material and method for manufacturing same, led support and method for manufacturing same

Abstract

The application relates to a composite material and a preparation method thereof, an LED support and a preparation method thereof. The composite material comprises an aluminum layer and a copper layer on the surface of the aluminum layer; the thickness of the copper layer is 10-25 mu m; the thickness ratio of the copper layer and the aluminum layer is 1: (2-10); a copper-aluminum intermetallic compound layer is arranged between the copper layer and the aluminum layer, the copper-aluminum intermetallic compound layer comprises a plurality of intermetallic compound sublayers arranged at intervals along a first direction, the first direction is the width direction of the composite material; and the thickness of the copper-aluminum intermetallic compound layer is 1-3 mu m.

Description

Technical Field

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

[0002] Light-emitting diodes (LEDs) are solid-state semiconductor devices with advantages such as energy saving, environmental friendliness, small size, low power consumption, high brightness, and long lifespan, and are currently widely used in various fields. LED brackets, as the basic material for LEDs, serve as the base before LED chip packaging. Chips are mounted on the LED bracket, positive and negative electrodes are soldered onto it, and then it is packaged to form the LED chip product. LED brackets need to have high thermal conductivity, high electrical conductivity, and a certain strength. Currently, common LED bracket materials include brass and copper, which are relatively expensive.

[0003] Using copper-aluminum composite materials as LED brackets can reduce their material costs. However, when traditional copper-aluminum composite materials are used to manufacture LED brackets, the following problems exist: (1) LED brackets need to undergo stamping, bending and other processes. Copper has higher strength than aluminum. During the stamping process, the aluminum layer is prone to plastic deformation and cracking, or peeling off from the copper layer, resulting in visible aluminum layer exposure. That is, aluminum leakage is likely to occur on the surface of the LED bracket; (2) The interfacial bonding force of copper-aluminum composite materials cannot resist bending stress, which can easily lead to the phenomenon of peeling between the copper layer and the aluminum layer during the bending process of the LED bracket. Summary of the Invention

[0004] Therefore, it is necessary to provide composite materials and their preparation methods, as well as LED brackets and their preparation methods. The composite material of this application can replace single-metal copper in the preparation of LED brackets to reduce their material costs, while having high interfacial bonding strength and good resistance to deformation and cracking, which can reduce the risk of surface aluminum leakage or interlayer delamination during the preparation of LED brackets.

[0005] In a first aspect, this application provides a composite material comprising an aluminum layer and a copper layer located on the surface of the aluminum layer; the thickness ratio of the copper layer to the aluminum layer is 1:(2~10); the thickness of the copper layer is 10μm~25μm; a copper-aluminum intermetallic compound layer is present 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 composite material; the thickness of the copper-aluminum intermetallic compound layer is 1μm~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 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 brass, and the thickness of the copper layer is 15μm to 25μm.

[0010] In some embodiments, the copper layer is pure copper, and the thickness of the copper layer is 10μm~20μm.

[0011] In some embodiments, two copper layers are included, with the two copper layers located on opposite sides of the aluminum layer.

[0012] In some embodiments, the thickness ratio of the two copper layers is 1:(0.5~2).

[0013] In some embodiments, the interfacial shear strength of the composite material is above 100 MPa.

[0014] In some embodiments, the conductivity of the composite material is 85% to 90% of that of pure aluminum.

[0015] In some embodiments, the elongation of the composite material is 7% to 9%.

[0016] Secondly, this application provides a method for preparing a composite material, comprising the following steps:

[0017] 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;

[0018] Copper plates and aluminum plates are stacked together, with the groove located between the copper plates and the aluminum plates;

[0019] 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.

[0020] The first composite material is subjected to a first annealing treatment;

[0021] The first composite plate after the first annealing treatment is subjected to a second rolling process to break up the continuous copper-aluminum intermetallic compound layer, thereby obtaining a second composite plate.

[0022] The second composite material is subjected to a second annealing treatment.

[0023] In some embodiments, the temperature of the first rolling is 380°C to 420°C.

[0024] In some embodiments, the total reduction rate of the first rolling is 52% to 70%.

[0025] In some embodiments, the first rolling is a single pass.

[0026] In some embodiments, the temperature of the first annealing treatment is 300°C to 420°C.

[0027] In some embodiments, the first annealing process takes 2 to 30 minutes.

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

[0029] In some embodiments, the second annealing process takes 0.5 h to 2 h.

[0030] In some embodiments, the width of the groove along the first direction is 15 μm to 30 μm.

[0031] In some embodiments, the spacing between two adjacent grooves along the first direction is 30 μm to 100 μm.

[0032] In some embodiments, the depth of the trench is 8 μm to 12 μm.

[0033] In some embodiments, the temperature of the second rolling is 250°C to 350°C, and the second rolling includes:

[0034] The first composite plate is subjected to one or two first sub-rolling passes to make the copper layer reach a first preset thickness, and the deformation of each first sub-rolling pass is 20% to 35%.

[0035] The first composite plate after the first sub-rolling is subjected to multiple passes of second sub-rolling, with the deformation amount of each second sub-rolling decreasing sequentially, and the deformation amount of each second sub-rolling being less than 20%, so that the copper layer reaches a second preset thickness, which is 10μm~25μm.

[0036] In some embodiments, the ratio of the first preset thickness to the second preset thickness is 1:(1.1~1.3).

[0037] In some embodiments, the process includes, prior to stacking the copper plate and the aluminum plate:

[0038] The surfaces of the copper plate and the aluminum plate having the grooves are roughened to make the surface roughness Ra of the copper plate and the aluminum plate having the grooves 1μm~6μm.

[0039] In some embodiments, the surfaces of the copper plate and the aluminum plate having the grooves are roughened using a wire brush and abrasive putty; the wire diameter of the wire brush is 0.08 mm to 0.12 mm; the abrasive putty includes a plastic matrix and silicon carbide abrasive.

[0040] Thirdly, this application provides an LED bracket comprising the composite material described in any one of the above-mentioned methods, or the composite material prepared by any one of the above-mentioned methods.

[0041] Fourthly, this application provides a method for manufacturing an LED bracket, comprising the following steps:

[0042] The composite material is prepared using any one of the methods described above;

[0043] The composite material is subjected to stamping and stretching, electroplating, injection molding, silver plating bending, die bonding and adhesive application, and lead welding in sequence.

[0044] In some embodiments, the stamping speed of the stamping and stretching is 300 times / minute to 700 times / minute.

[0045] In some embodiments, the electroplating includes the following steps: pre-plating a copper plating layer with a thickness of 0.5 μm to 0.6 μm, plating a nickel plating layer with a thickness of 0.5 μm to 0.6 μm on the copper plating layer, and plating a silver plating layer with a thickness of 0.35 μm to 0.38 μm on the nickel plating layer.

[0046] In some embodiments, the temperature of the injection mold is 100°C to 140°C.

[0047] In some embodiments, the injection pressure of the injection molding is 80MPa to 120MPa.

[0048] In some embodiments, the holding time of the injection molding is 5s to 10s.

[0049] In some embodiments, the cooling time of the injection molding is 10s to 20s.

[0050] In some embodiments, the bending angle deviation is controlled to ±10° during the silver-plated foot bending.

[0051] In some embodiments, the curing temperature of the die-bonding adhesive is 180°C to 200°C.

[0052] In some embodiments, the curing time of the die-bonding adhesive is 110 min to 130 min.

[0053] In the aforementioned composite materials, the aluminum layer has a lower density and better thermal conductivity, giving it an advantage over single copper metal materials in terms of thermal conductivity. This results in better heat dissipation when used as a material for LED brackets. Simultaneously, the copper-aluminum intermetallic compound layer at the interface between the copper and aluminum layers is relatively thin, ranging from 1μm to 3μm, and exhibits a discontinuous, interlocking distribution. The intermetallic compound is diffusely distributed at the interface. This avoids the continuity of the intermetallic compound, reducing the three-layer structure of copper-IMC-aluminum, and maintaining a discontinuous two-layer structure of direct copper-aluminum bonding at the interface. Furthermore, the discontinuous intermetallic compound increases the specific surface area of ​​the intermetallic compound and the copper and aluminum matrices, further enhancing the interfacial bonding strength. This ensures that the copper and aluminum layers do not delaminate during processes such as stamping, stretching, foot bending, baking, and reflow soldering in the LED bracket manufacturing process. Furthermore, by rationally allocating the thickness ratio of the aluminum and copper layers, the core functional requirements of the aluminum layer are guaranteed, while ensuring that the outer copper layer has sufficient coverage and structural strength. This provides a basic structural guarantee to avoid aluminum leakage. At the same time, the thickness of the single-layer copper layer is precisely controlled, reducing copper usage and production costs while ensuring the integrity of the copper layer and preventing aluminum leakage defects caused by excessively thin or damaged copper layers. In other words, the composite material of this application can replace single-metal copper in the fabrication of LED brackets to reduce material costs. It also has high interfacial bonding strength and good resistance to deformation and cracking, which can reduce the risk of surface aluminum leakage or interlayer delamination during the fabrication of LED brackets. Attached Figure Description

[0054] Figure 1 A schematic diagram of the structure of the composite material provided in one embodiment of this application;

[0055] Figure 2 SEM image of a cross section of a composite material provided in one embodiment of this application;

[0056] Figure 3 This is a schematic cross-sectional view of the composite material prepared according to one embodiment of this application;

[0057] Figure 4 This is a schematic diagram of the surface of the composite material prepared according to one embodiment of this application;

[0058] Figure 5 This is a schematic cross-sectional view of the composite material prepared according to another embodiment of this application;

[0059] Figure 6 This is a schematic diagram of the surface of the composite material prepared according to another embodiment of this application.

[0060] Explanation of reference numerals in the attached figures:

[0061] 10-Copper layer; 20-Aluminum layer; 30-Copper-aluminum intermetallic compound layer; 31-Intermetallic compound sublayer. Detailed Implementation

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Reference Figure 1 As shown, one embodiment of this application provides a composite material, including an aluminum layer 20 and a copper layer 10 located on the side of the aluminum layer 20; the thickness ratio of the copper layer 10 to the aluminum layer 20 is 1:(2~10); the thickness of the copper layer 10 is 10μm~25μm; 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 includes a plurality of intermetallic compound sublayers 31 spaced apart along a first direction, the first direction being the width direction of the composite material; the thickness of the copper-aluminum intermetallic compound layer 30 is 1μm~3μm.

[0068] Among the aforementioned composite materials, the aluminum layer 20 material has a lower density and better thermal conductivity, giving it an advantage over single copper metal materials in terms of thermal conductivity. Therefore, as a material for LED brackets, it can provide better heat dissipation. (Refer to...) Figures 3-6 As shown, the copper-aluminum intermetallic compound layer 30 at the interface between copper layer 10 and aluminum layer 20 is relatively thin, ranging from 1 μm to 3 μm, and exhibits a discontinuous interlocking distribution at the 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 substrates, further enhancing the interfacial bonding strength. This ensures that during the LED bracket fabrication process, including stamping, stretching, foot bending, baking, and reflow soldering, the copper layer 10 and aluminum layer 20 do not delaminate. Furthermore, by rationally allocating the thickness ratio of the aluminum layer 20 and the copper layer 10, the core functional requirements of the aluminum layer 20 are guaranteed, while ensuring that the outer copper layer 10 has sufficient coverage and structural strength. This provides a basic structural guarantee to avoid aluminum leakage. At the same time, the thickness of the single-layer finished outer copper layer is precisely controlled, reducing copper usage and controlling production costs while ensuring that the copper layer 10 is intact and undamaged, eliminating aluminum leakage defects caused by the copper layer 10 being too thin or damaged. In other words, the composite material of this application can replace single-metal copper in the preparation of LED brackets to reduce their material costs. It also has high interfacial bonding strength and good resistance to deformation and cracking, which can reduce the risk of surface aluminum leakage or interlayer delamination during the preparation of LED brackets.

[0069] It should be noted that the thickness ratio of copper layer 10 to aluminum layer 20 is 1:(2~10), the thickness of copper layer 10 is 10μm~25μm, and the thickness of copper-aluminum intermetallic compound layer 30 is 1μm~3μm. These three sets of parameters are not isolated values, but rather a layered constraint relationship involving structural layer proportions, interface control, and overall performance. From a feasibility perspective, the thickness of copper layer 10 and the thickness ratio of copper layer 10 to aluminum layer 20 are mutually constraining. If only the thickness ratio is limited without limiting the thickness of copper layer 10, copper layer 10 may be too thin and easily break, resulting in aluminum leakage, or it may be too thick, leading to insignificant cost reduction. If only the thickness of copper layer 10 is limited without limiting the thickness ratio, it is impossible to ensure that the aluminum layer has sufficient thickness to leverage its low density and high thermal conductivity advantages, and it is also impossible to stably control the copper content to reduce costs.

[0070] The above parameters work together to achieve cost reduction, ensure heat dissipation, and prevent aluminum leakage. Within the thickness range of the copper layer 10, the outer layer coverage and structural strength are guaranteed, structurally preventing aluminum leakage while avoiding excessive copper usage that would negate the cost advantage of replacing pure copper. Within the thickness ratio range, the aluminum layer 20 is prevented from being too thin, resulting in insufficient thermal conductivity / weight reduction, and the copper layer 10 is prevented from being too thin, leading to insufficient copper layer 10 and easy breakage when the overall material thickness is thin. In other words, the thickness of the copper layer 10 provides an absolute safe range, and the copper-aluminum thickness ratio provides a relative structural proportion. Together, they define an feasible range that can prevent aluminum leakage, reduce costs, and ensure the thermal conductivity of the aluminum layer 20.

[0071] Furthermore, the aluminum layer 20 provides the main body thickness, thermal conductivity, and strength framework, while the copper layer 10 provides surface conductivity / solderability and prevents aluminum leakage. The IMC layer is responsible for the copper-aluminum interface bonding. The thickness of the IMC layer, 1μm to 3μm, must be based on the aforementioned stable core-shell structure. To address the core pain points of copper-aluminum composite materials, such as brittle interfaces and easy delamination, the copper-aluminum intermetallic compound layer 30 has a thickness of 1μm to 3μm. This avoids insufficient metallurgical bonding and low interface bonding strength caused by excessive thinness, as well as the tendency for continuous thick layers to cause interface cracking and delamination due to excessive thickness. Simultaneously, in this application, the copper-aluminum intermetallic compound layer 30 is diffusely distributed, which can retain sufficient metallurgical bonding force while avoiding the brittleness of continuous thick IMC layers and increasing the specific surface area for bonding with the copper and aluminum substrates. The realization of the above technical effects also depends on the copper layer not cracking or leaking aluminum; the aluminum layer 20 provides overall rigidity to withstand stamping, bending, and reflow soldering.

[0072] Therefore, the three parameters mentioned above are strongly coupled and indispensable. The first two groups jointly determine the main structure and basic function of the composite material, while the third group achieves optimal control of the interface performance on this structure. Only through the synergy of these three groups can the following technical effects be achieved simultaneously: cost reduction by replacing pure copper, high heat dissipation, high interface bonding strength, resistance to impact and bending, and no aluminum leakage or delamination.

[0073] Refer again Figure 1 As shown, exemplarily, Figure 1 The X-direction is the first direction. Figure 1 The Y-direction refers to the thickness direction of the composite material. Specifically, the thickness of the copper-aluminum intermetallic compound layer 30 refers to the thickness of each intermetallic compound sublayer 31 being 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 2 As shown, Figure 2 The scanning electron microscope image of the cross section of the composite material provided in one 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.

[0074] Furthermore, compared to traditional copper-aluminum composite materials, the composite material of this application controls the thickness of each intermetallic compound sublayer 31 to be within the range of 1μm to 3μm. While achieving high interfacial metallurgical bonding strength, it can also effectively avoid problems such as insufficient interfacial bonding force caused by excessive thickness and brittleness of the intermetallic compound (IMC) layer, thereby making the composite material have high reliability.

[0075] Optionally, the thickness of the copper layer 10 is 10μm, 12μm, 15μm, 18μm, 20μm, 22μm or 25μm, or the thickness of the copper layer 10 may be within any two of the above-mentioned thicknesses.

[0076] When the thickness ratio of copper layer 10 to aluminum layer 20 is too large, that is, when the thickness of copper layer 10 accounts for a large proportion, the cost-saving improvement effect is not significant. When the thickness ratio of copper layer 10 to aluminum layer 20 is too small, that is, when the thickness of copper layer 10 is too thin, when the overall thickness of the composite material is thin, the thickness of copper layer 10 will be too thin, thereby increasing the risk of aluminum leakage.

[0077] Optionally, the thickness ratio of the copper layer 10 to the aluminum layer 20 is 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, or the thickness ratio of the copper layer 10 to the aluminum layer 20 can be within the range of any two of the above thickness ratios.

[0078] In some embodiments, the first direction is perpendicular to the thickness direction of the composite material.

[0079] 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 composite material.

[0080] Within the range of the percentage of the total width of each intermetallic compound sublayer 31 to the width of the composite material, it is easy to achieve a higher interfacial bonding strength of the 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 becoming insufficient due to the total width of each intermetallic compound sublayer 31 being too narrow.

[0081] Optionally, in the first direction, the percentage of the total width of each intermetallic compound sublayer 31 to the width of the 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 composite material may be within the range of any two of the above percentages.

[0082] In some embodiments, each intermetallic compound sublayer 31 has an independent width of less than 1 μm in the first direction.

[0083] 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 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.

[0084] 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.

[0085] In some embodiments, the distance between two adjacent intermetallic compound sublayers 31 is 0.5 μm to 5 μm.

[0086] 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 of the 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.

[0087] 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.

[0088] The composite material in this application embodiment, by reasonably allocating the thickness ratio of the aluminum layer 20 and the copper layer 10, not only ensures the core functional requirements of the aluminum layer 20, but also ensures that the outer copper layer 10 has sufficient coverage and structural strength, providing a basic structural guarantee to avoid aluminum leakage. At the same time, it precisely controls the finished thickness of the single layer of outer copper, reducing the amount of copper used and controlling production costs, while ensuring that the copper layer 10 is intact and undamaged, and eliminating aluminum leakage defects caused by the copper layer 10 being too thin or damaged.

[0089] In some embodiments, two copper layers 10 are included, which are located on two opposite surfaces of the aluminum layer 20.

[0090] In some embodiments, the thickness ratio of the two copper layers 10 is 1:(0.5~2).

[0091] Optionally, the thickness ratio of the two copper layers 10 is 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8 or 1:2, or the thickness ratio of the two copper layers 10 can be within the range of any two of the above thickness ratios.

[0092] In some embodiments, the copper layer 10 is brass, and the thickness of the copper layer 10 is 15μm to 25μm.

[0093] Optionally, the thickness of the copper layer 10 is 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm or 25μm, or the thickness of the copper layer 10 may be within any two of the above-mentioned thicknesses.

[0094] In some embodiments, the copper layer 10 is copper, and the thickness of the copper layer 10 is 10μm to 20μm.

[0095] Optionally, the thickness of the copper layer 10 is 10μm, 12μm, 14μm, 16μm, 18μm or 20μm, or the thickness of the copper layer 10 may be within any two of the above thicknesses.

[0096] In some embodiments, the interfacial shear strength of the composite material is above 100 MPa.

[0097] Traditional copper-aluminum composite materials typically have an interfacial shear strength of 60 MPa to 70 MPa, while the composite material of this application exhibits a significantly improved interfacial shear strength. Optionally, the interfacial shear strength of the composite material is 100 MPa to 140 MPa. More preferably, the interfacial shear strength of the composite material is 120 MPa to 140 MPa. Further preferably, the interfacial shear strength of the composite material is 120 MPa, 122 MPa, 124 MPa, 126 MPa, 128 MPa, 130 MPa, 132 MPa, 134 MPa, 136 MPa, 138 MPa, or 140 MPa, or the interfacial shear strength of the composite material may fall within the range of any two of the above shear strengths.

[0098] 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".

[0099] It should be noted that the shear strength test requires a copper-aluminum-copper layered composite material with a thickness of not less than 0.6 mm. Copper-aluminum-copper layered composite materials with a thickness less than 0.6 mm are difficult to test for shear strength; therefore, the method of determining the shear strength is based on the absence of delamination after multiple bending fractures. The copper-aluminum-copper layered composite material of this application embodiment can achieve a shear strength of ≥8 cycles, and the copper and aluminum do not delaminate after fracture, meaning the interfacial strength of the copper-aluminum-copper layered composite material is greater than the strength of a single layer of material itself.

[0100] In some embodiments, the conductivity of the composite material is 85% to 90% of that of pure aluminum.

[0101] Optionally, the conductivity of the composite material is 85%, 86%, 87%, 88%, 89%, or 90% of the conductivity of pure aluminum, or the percentage of the conductivity of the composite material to the conductivity of pure aluminum can be within any two of the above percentages.

[0102] In some embodiments, the conductivity of the composite material is 55% IACS to 60% IACS.

[0103] Optionally, the conductivity of the composite material is 55% IACS, 56% IACS, 57% IACS, 58% IACS, 59% IACS or 60% IACS, or the conductivity of the composite material may be within the range of any two of the above conductivity values.

[0104] In some of these embodiments, the elongation of the composite material is 7% to 9%.

[0105] By controlling the overall elongation of the composite material to 7%~9%, the risk of stamping tensile fracture and interlayer delamination can be reduced from the root by balancing the plastic deformation capacity of the copper layer 10 and the aluminum layer 20 and matching the strain requirements of the LED bracket stamping and bending processes. This elongation avoids excessive deformation of the copper layer 10 due to excessive elongation, which would cause additional tensile load on the aluminum core layer. It also prevents insufficient plasticity reserve of the material due to excessive elongation, which would lead to rapid brittle fracture under stamping stress. At the same time, it ensures that the shear stress at the copper-aluminum interface is always within the tolerance range of the interface bonding strength, ensuring that there is no interlayer delamination or aluminum core layer fracture after stamping, thereby improving the yield and structural stability of the LED bracket stamping process. Optionally, the elongation of the composite material can be 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, or 9%, or the elongation of the composite material can be within any two of the above elongation rates.

[0106] In some embodiments, the composite material is prepared by the composite material preparation method of this application.

[0107] Another embodiment of this application provides a method for preparing a composite material, comprising the following steps:

[0108] 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;

[0109] The copper and aluminum plates are stacked together so that the groove is located between the copper and aluminum plates;

[0110] 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.

[0111] The first composite board is subjected to a first annealing treatment;

[0112] The first composite plate after the first annealing treatment is subjected to a second rolling process to break up the continuous copper-aluminum intermetallic compound layer 30, thereby obtaining a second composite plate.

[0113] The second composite board is subjected to a second annealing treatment.

[0114] In the composite material preparation method of this application embodiment, the first stage is "interface prefabrication." If the surfaces of both the copper and aluminum plates are smooth planes, rolling will only form a pressed rather than interlocked serrated interface. 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, copper and aluminum undergo intense plastic flow, and aluminum fully fills the grooves, achieving 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 composite material preparation method of this application embodiment can prepare a composite material with a discontinuous and relatively thin copper-aluminum intermetallic compound layer 30, and it has high interfacial bonding strength.

[0115] When the first composite sheet passes through the rolls again, the copper layer 10 undergoes coordinated plastic deformation with the aluminum matrix. Due to the brittleness and hardness of the IMC layer, it cannot deform in coordination, generating enormous shear stress 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 broken IMC, allowing the fresh brass and fresh aluminum in the lower layer to come into direct contact, forming new metallurgical bonding points with little or no IMC. This reduces the three-layer structure while maintaining direct brass-aluminum bonding. 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.

[0116] In some embodiments, the temperature of the first rolling is 380°C to 420°C.

[0117] 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.

[0118] In some embodiments, the total reduction rate of the first rolling is 52% to 70%.

[0119] 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.

[0120] In some implementations, the first rolling is a single pass.

[0121] In some embodiments, the first rolling is performed in a protective gas atmosphere.

[0122] Through the first rolling process, under the combined action of heat and force, preliminary metallurgical bonding of the matrix is ​​achieved, intentionally generating a continuous and complete initial IMC layer with controllable thickness. The temperature of the first rolling is a critical technical window. If the first rolling temperature is too low, IMC formation is too slow, resulting in weak bonding. If the first rolling temperature 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 which sufficient plastic deformation can be ensured for adequate contact and diffusion of fresh metal at the interface. The first rolling is carried out in a protective gas atmosphere to minimize interface oxidation. During this stage, copper and aluminum adhere tightly under high pressure, and high temperature drives rapid atomic interdiffusion, forming a continuous IMC layer at the interface. This layer is the raw material for subsequent crushing operations.

[0123] In some embodiments, the temperature of the first annealing treatment is 300°C to 420°C.

[0124] Optionally, the temperature of the first annealing treatment is 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, or 420°C, or the temperature of the first annealing treatment may be within the range of any two of the above temperatures.

[0125] In some embodiments, the first annealing process takes 2 to 30 minutes.

[0126] Optionally, the time for the first annealing process is 2 min, 2 min, 10 min, 15 min, 20 min, 25 min, or 30 min, or the time for the first annealing process can be within any two of the above times.

[0127] Within the temperature and time range of the first annealing treatment described above, the copper layer 10 fully recrystallizes and regains its plasticity. More importantly, at the copper-aluminum interface, atoms diffuse into each other to form a thin and continuous intermetallic compound transition layer. If this transition layer is too thick, it will be brittle. By controlling the temperature and time in this application, a dense diffusion layer with a thickness of nanometer to micrometer can be formed to connect the two metals, significantly improving the interfacial bonding strength and shear resistance, making the interface less prone to separation during subsequent deformation.

[0128] In some embodiments, the temperature of the second annealing treatment is 180°C to 250°C.

[0129] Optionally, the temperature of the second annealing treatment is 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C, or the temperature of the second annealing treatment may be within the range of any two of the above temperatures.

[0130] In some embodiments, the second annealing process takes 0.5 h to 2 h.

[0131] Optionally, the time for the second annealing process is 0.5h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h, or 2h, or the time for the second annealing process can be within any two of the above times.

[0132] The second annealing process releases the processing stress generated during 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. The second annealing can be performed in air or a protective atmosphere, where oxidation is controllable. At lower temperatures, atoms undergo only short-range diffusion, sufficient to relax interfacial stress and improve the wettability of the IMC particles to the matrix, but far from enough to significantly coarsen or bond the IMC particles.

[0133] In some embodiments, the width of the groove along the first direction is 15 μm to 30 μm.

[0134] 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.

[0135] In some embodiments, the spacing between two adjacent trenches along the first direction is 30 μm to 100 μm.

[0136] 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 two widths mentioned above.

[0137] In some embodiments, the depth of the trench is 8 μm to 12 μm.

[0138] 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.

[0139] 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 an intermetallic compound sublayer 31 with appropriate size and distribution, thereby achieving a good interfacial bonding strength of the copper-aluminum layer 20 composite material.

[0140] In some embodiments, the temperature of the second rolling is 250°C to 350°C, and the second rolling includes:

[0141] The first composite plate is subjected to one or two first sub-rolling processes to make the copper layer 10 reach the first preset thickness, and the deformation of each first sub-rolling is 20%~35%;

[0142] The first composite plate after the first sub-rolling is subjected to multiple passes of second sub-rolling. The deformation of each second sub-rolling decreases sequentially, and the deformation of each second sub-rolling is less than 20%, so that the copper layer 10 reaches the second preset thickness, which is 10μm~25μm.

[0143] In the composite material preparation method of this application embodiment, the first rolling temperature is 380℃~420℃, and the total reduction rate of the first rolling is 52%~70%. At this temperature, the deformation resistance of the material is reduced, allowing copper and aluminum to interlock in a softer state. Simultaneously, the appropriate amount of deformation ensures sufficient initial bonding strength while significantly reducing dislocation pile-up and micro-stress concentration caused by excessive deformation, creating a low-stress interface starting point for subsequent processing. Meanwhile, the first annealing temperature is 300℃~420℃, and the time is 2min~30min. Annealing at this temperature allows the copper layer 10 to fully recrystallize and regain its plasticity. More importantly, at the copper-aluminum interface, atoms diffuse to form a thin and continuous intermetallic compound transition layer. If this transition layer is too thick, it will be brittle. Through the temperature and time control of this application, a dense diffusion layer with a thickness of nanometer to micrometer can be formed to connect the two metals, significantly improving the interfacial bonding strength and shear resistance, making the interface less prone to separation during subsequent deformation. Furthermore, the temperature for the second annealing treatment is 180℃~250℃. When the copper layer 10 is still relatively thick, one or two large deformation passes are used to utilize the plasticity brought about by the increased temperature, allowing the interface to be further strengthened under higher stress. When the copper layer 10 approaches the target ultrathin thickness, the rolling mode is switched to multi-pass, small-deformation rolling. Each small deformation pass provides sufficient time for the copper layer 10 and aluminum layer 20 to flow in coordination, dispersing the interfacial shear stress and avoiding concentrated stress that could trigger cracks at local weak points in the copper layer 10. Maintaining the temperature keeps the copper layer 10 in a good plastic state, making it less prone to brittleness. In other words, the composite material preparation method of this application can overcome the problem of surface aluminum leakage when preparing composite materials with ultrathin copper layers 10 in traditional methods, and thus can prepare composite materials with a copper layer 10 thickness of 10μm~25μm.

[0144] Optionally, the temperature of the second rolling process is 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, or 350°C, or the temperature of the second rolling process may be within the range of any two of the above temperatures.

[0145] Optionally, the deformation amount of each first sub-roll is 20%, 22%, 25%, 28%, 30%, 32% or 35%, or the deformation amount of each first sub-roll can be within the range of any two of the above deformation amounts.

[0146] Optionally, the deformation amount of each second sub-roll is 0.1% to 20%. More preferably, the deformation amount of each second sub-roll is 0.1%, 0.2%, 0.5%, 0.8%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%. Alternatively, the deformation amount of each second sub-roll can be within the range of any two of the above deformation amounts.

[0147] In some embodiments, the ratio of the first preset thickness to the second preset thickness is 1:(1.1~1.3).

[0148] Optionally, the ratio of the first preset thickness to the second preset thickness is 1:1.1, 1:1.12, 1:1.15, 1:1.18, 1:1.2, 1:1.22, 1:1.25, 1:1.28 or 1:1.3, or the ratio of the first preset thickness to the second preset thickness may be within the range of any two of the above ratios.

[0149] In some embodiments, the following steps are included before the copper and aluminum plates are stacked:

[0150] The grooved surfaces of copper and aluminum plates are roughened to achieve a surface roughness Ra of 1 μm to 6 μm.

[0151] In some embodiments, the grooved surfaces of copper and aluminum plates are roughened using a wire brush and abrasive putty; the wire diameter of the wire brush is 0.08 mm to 0.12 mm; the abrasive putty includes a plastic matrix and silicon carbide abrasive.

[0152] Using an ultra-fine steel wire brush with a wire diameter of 0.08mm~0.12mm combined with an abrasive brush to roughen the bonding surfaces of the first copper, aluminum, and second copper materials results in a more uniform and delicate surface. This replaces the traditional coarse steel wire brush, creating fine, uniform, and shallow scratches on the surface. This increases the bonding surface area, promotes mechanical interlocking, and avoids the formation of excessively deep grooves that could easily become crack initiations.

[0153] Optionally, the roughness Ra of the mating surface is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or 6 μm, or the roughness Ra of the mating surface may be within the range of any two of the above roughnesses.

[0154] Optionally, the wire diameter of the wire brush is 0.08mm, 0.09mm, 0.1mm, 0.11mm or 0.12mm, or the wire diameter can be within any two of the above ranges.

[0155] Furthermore, this application achieves the following beneficial effects through the above-described method for preparing composite materials:

[0156] (1) Using copper-aluminum alloy-copper composite material to make LED bracket material has a significant advantage in material cost compared to traditional brass material. At the same time, the single material has low density and light weight, and less material is consumed for the same bracket, which can further reduce material cost. By stacking copper-aluminum alloy-copper layers and using solid rolling for composite, the three-layer composite material can replace the single metal, which can significantly reduce the cost. At the same time, the low density of aluminum alloy means that less LED bracket material is consumed when arranging LED beads at the same density during the manufacturing process of LED bracket, which further reduces the cost.

[0157] (2) Copper-aluminum alloy-copper composite material is used. Since aluminum alloy has better thermal conductivity, it is more conducive to the heat dissipation of LED bracket, reducing the failure of LED beads caused by thermal stress, and is more conducive to the heat dissipation of LED beads. The LED bracket can diffuse the heat of the LED beads. Therefore, thermal conductivity is crucial for the LED bracket. Good thermal conductivity can meet the heat generation of higher power LED beads. At the same time, thermal stress generated by thermal shock is also the main cause of LED bead failure. Since the thermal conductivity of aluminum alloy is much higher than that of brass, brass-aluminum alloy-brass and copper-aluminum alloy-copper are better than single metal brass in terms of thermal conductivity, which is more conducive to the heat dissipation of LED beads.

[0158] Traditional single-metal brass LED brackets, when the LED chips are arranged in a high density, release a large amount of heat. The thermal conductivity of brass is inferior to that of aluminum alloy, making it difficult to effectively dissipate the heat released by high-density or high-power LED chips. Based on this description, using aluminum alloy as the interlayer material in the composite material offers advantages in heat dissipation. Aluminum alloy's thermal conductivity is approximately twice that of brass. Therefore, for LED brackets with the same density arrangement, a brass-aluminum alloy-brass composite material provides a significant advantage in LED chip heat dissipation. Furthermore, a copper-aluminum alloy-copper composite material offers even better thermal conductivity than a brass-aluminum alloy-brass composite material, allowing for selection based on different scenarios and cost requirements.

[0159] (3) The online texturing + solid rolling composite is adopted to control the discontinuous morphology of the interface IMC layer and improve the high bonding strength of the composite material. During the processes of stamping, stretching, silver foot bending and baking reflow soldering of the LED bracket, the composite material does not delaminate.

[0160] (4) High surface cleanliness and low roughness: The surface cleanliness and roughness of the composite material will affect the subsequent stamping, electroplating and other processing of the LED bracket. In the preparation of the composite material, multiple small-pressure passes are adopted, and the surface roughness of the rolls and the surface cleanliness of the finished product are strictly controlled to meet the requirements of the subsequent processing of the LED bracket.

[0161] (5) No aluminum leakage on the surface: A higher copper thickness ratio is more conducive to no aluminum leakage on the material surface, but it increases the material cost. Therefore, it is necessary to strictly control the copper layer thickness ratio. While ensuring the material cost advantage, the risk of no aluminum leakage on the material surface can be mitigated by precisely controlling the thickness ratio of brass or copper and aluminum alloy composites, as well as precise tension control during rolling, and control of stamping and bending in the post-processing of LED brackets. The thickness of the brass layer should not be less than 15μm, and the thickness of the copper layer should not be less than 10μm.

[0162] (6) High bonding without delamination during bending: Brass-aluminum alloy-brass and copper-aluminum alloy-copper are bonded together by solid rolling and single-pass large reduction, so that the copper and aluminum alloy interface forms a high bonding strength. Referring to the peel strength in GB / T32468-2025, the copper and aluminum do not delaminate after bending and breaking.

[0163] (7) Consistent mechanical properties: By adjusting the thickness ratio of different brass-aluminum alloy-brass and copper-aluminum alloy-copper, the mechanical properties of the composite material are ensured to be close to those of single metal brass.

[0164] Another embodiment of this application provides an LED bracket comprising the composite material of any one of the above-mentioned claims, or the composite material prepared by the preparation method of the composite material of any one of the above-mentioned claims.

[0165] Another embodiment of this application provides a method for manufacturing an LED bracket, comprising the following steps:

[0166] Composite materials are prepared using any of the above-mentioned methods for preparing composite materials;

[0167] The composite material is subjected to stamping and stretching, electroplating, injection molding, silver plating and bending, die bonding and adhesive application, and lead welding in sequence.

[0168] In some embodiments, the method for preparing the LED bracket includes the following steps:

[0169] Composite materials are prepared using any of the above-mentioned methods for preparing composite materials;

[0170] The composite material is sequentially slited, surface alkaline washing, surface acid washing, pure water rinsing, and hot air drying.

[0171] A continuous stamping press is used to stamp the composite material using molds. The stamping steps are: stamping of positioning holes, preforming of pins, stretching of cup body, and cutting of shape.

[0172] The semi-finished LED bracket after stamping and stretching is electroplated with copper with a thickness of 0.5μm~0.6μm, nickel with a thickness of 0.5μm~0.6μm, and silver with a thickness of 0.35μm~0.38μm in sequence.

[0173] The LED bracket semi-finished product is injection molded using an injection molding machine. The mold temperature is 100℃~140℃, the injection pressure is 80MPa~120MPa, the holding time is 5s~10s, and the cooling time is 10s~20s.

[0174] After injection molding, the silver-plated feet are bent flat, and the bending angle deviation is controlled within ±10°.

[0175] The LED bracket semi-finished product was coated with adhesive using a dispensing machine and then baked to cure. The baking temperature was 180℃~200℃ and the baking time was 110min~130min.

[0176] After baking, leads are soldered to the positive and negative terminals of the LED chip, and then a sealing machine is used for sealing.

[0177] In some embodiments, the stamping speed of the stamping and stretching is 300 times / minute to 700 times / minute.

[0178] Optionally, the stamping speed of the stamping and drawing process is 300 times / minute, 400 times / minute, 500 times / minute, 600 times / minute, or 700 times / minute, or the stamping speed of the stamping and drawing process can be within the range of any two of the above speeds.

[0179] In some embodiments, electroplating includes the following steps: pre-plating a copper plating layer with a thickness of 0.5 μm to 0.6 μm, plating a nickel plating layer with a thickness of 0.5 μm to 0.6 μm on the copper plating layer, and plating a silver plating layer with a thickness of 0.35 μm to 0.38 μm on the nickel plating layer.

[0180] Optionally, the thickness of the copper plating layer is 0.5μm, 0.52μm, 0.54μm, 0.56μm, 0.58μm or 0.6μm, or the thickness of the copper plating layer may be within any two of the above-mentioned thicknesses.

[0181] Optionally, the thickness of the nickel plating layer is 0.5 μm, 0.52 μm, 0.54 μm, 0.56 μm, 0.58 μm or 0.6 μm, or the thickness of the nickel plating layer may be within any two of the above-mentioned thicknesses.

[0182] Optionally, the thickness of the silver plating layer is 0.35μm, 0.36μm, 0.37μm or 0.38μm, or the thickness of the silver plating layer may be within any two of the above-mentioned thicknesses.

[0183] In some of these embodiments, the injection mold temperature is 100°C to 140°C.

[0184] Optionally, the injection mold temperature is 100°C, 110°C, 120°C, 130°C or 140°C, or the injection mold temperature may be within the range of any two of the above temperatures.

[0185] In some embodiments, the injection pressure is 80 MPa to 120 MPa.

[0186] Optionally, the injection pressure of the injection molding is 80MPa, 90MPa, 100MPa, 110MPa or 120MPa, or the injection pressure of the injection molding can be within the range of any two of the above pressures.

[0187] In some of these embodiments, the holding time for injection molding is 5 to 10 seconds.

[0188] Optionally, the holding time for injection molding is 5s, 6s, 7s, 8s, 9s or 10s, or the holding time for injection molding can be within any two of the above times.

[0189] In some of these embodiments, the cooling time for injection molding is 10 to 20 seconds.

[0190] Optionally, the cooling time for injection molding is 10s, 12s, 14s, 16s, 18s, or 20s. Alternatively, the cooling time for injection molding can also be within any two of the above-mentioned times.

[0191] In some embodiments, the bending angle deviation is controlled within ±10° during the bending of the silver-plated foot.

[0192] In some embodiments, the curing temperature of the die-bonding adhesive is 180°C to 200°C.

[0193] Optionally, the curing temperature of the die bond adhesive is 180°C, 185°C, 190°C, 195°C or 200°C, or the curing temperature of the die bond adhesive can be within the range of any two of the above temperatures.

[0194] In some embodiments, the curing time of the die-bonding adhesive is 110 min to 130 min.

[0195] Optionally, the curing time of the die bond adhesive is 110 min, 115 min, 120 min, 125 min or 130 min, or the curing time of the die bond adhesive can be within the range of any two of the above times.

[0196] The following are specific examples:

[0197] Example 1

[0198] Example 1 uses 5083 aluminum alloy and C2680 brass alloy to prepare a composite material with a thickness ratio of C2680:5083:C2680=1:6:1. The composite material has a size of 0.18mm×74mm×Coil.

[0199] The composite material is manufactured using an online dry texturing + solid-state cold rolling process. The texturized material is rolled using a four-roll cold composite mill with a single-pass reduction of 65%. The final composite size is 0.70mm ± 0.05mm, and the rolling speed is 2m / min. After composite processing, annealing is performed in a continuous annealing furnace with nitrogen protection to prevent oxidation. After diffusion annealing, the material undergoes edge trimming and brushing, followed by further cold rolling on a twenty-roll mill with multiple passes and low reduction rates. The single-pass reduction rate is controlled at 15%~20%, for a total of four rolling passes. Rolling tension and roll roughness are controlled throughout the process. The composite roll material is then slit and cleaned to ensure surface cleanliness before being fed into a continuous stamping die for step-by-step stamping of positioning holes, leads, cups, and other external shapes. After stamping, electroplating is performed, with sequential plating of copper, nickel, and silver, followed by chemical passivation to prevent oxidation. The LED bracket is injection molded using an injection molding machine, and the silver-plated corners are bent after injection molding. Adhesive is then applied to the LED bracket using a dispensing machine, the LED chips are installed, baked and cured, leads are soldered, and then sealed with adhesive. After the LED chips are removed from the bracket, they undergo electrical testing and sorting, and are then packaged.

[0200] Example 2

[0201] In this embodiment 2, 5083 aluminum alloy and C2680 brass alloy were used to prepare a composite material with the ratio C2680:5083:C2680=1:8:1. The composite material has a size of 0.15mm×76mm×Coil.

[0202] The composite material is manufactured using an online dry texturing + solid-state cold rolling process. The texturized material is rolled using a four-roll cold composite mill with a single-pass reduction rate of 67%. The composite dimension is 0.60mm ± 0.05mm, and the rolling speed is 1.8m / min. After composite processing, diffusion annealing is performed in a continuous annealing furnace with nitrogen protection to prevent oxidation. After diffusion annealing, the material is trimmed and brushed, followed by further cold rolling. This is done in a 20-roll mill with multiple passes of low-reduction rolling deformation, with a single-pass reduction rate controlled at 15%~20%, for a total of 4 rolling passes. During the process, rolling tension and roll roughness are controlled. A continuous stamping and stretching die is used to perform step-by-step continuous stamping and stretching of the composite material. Subsequent processes such as electroplating, injection molding, and bending are described in Example 1.

[0203] Comparative Example 1

[0204] The composite material and its preparation method in Comparative Example 1 are basically the same as those in Example 1, except that the thickness ratio C2680:5083:C2680 = 1:1:1.

[0205] In Comparative Example 1, the aluminum layer 20 has a small thickness in the composite material, which does not provide an advantage in saving costs.

[0206] Comparative Example 2

[0207] The composite material and its preparation method in Comparative Example 2 are basically the same as those in Example 1, except that the thickness ratio C2680:5083:C2680 = 1:15:1.

[0208] In Comparative Example 2, the thickness of the copper layer 10 in the composite material is too small, that is, the thickness of the copper layer 10 is too thin. The ability of copper and aluminum to deform together is poor. When preparing composite materials with a thin overall thickness, the risk of aluminum leakage is high and it is difficult to control the problem of aluminum leakage.

[0209] Comparative Example 3

[0210] The composite material and its preparation method in Comparative Example 3 are basically the same as those in Example 1, except that the thickness ratio C2680:5083:C2680 = 1:6:0.25.

[0211] In Comparative Example 3, one of the copper layers, 10, is too thin, which can easily lead to aluminum leakage. At the same time, asymmetric rolling increases the rolling difficulty, makes the plate shape uncontrollable, and can easily cause problems such as plate warping, affecting subsequent stamping and other processes.

[0212] Comparative Example 4

[0213] The composite material and its preparation method in Comparative Example 4 are basically the same as those in Example 1, except that the thickness ratio C2680:5083:C2680 = 1:6:3.

[0214] In Comparative Example 4, one of the copper layers (10) is too thick, which increases the cost of the composite material and negates its cost advantage. Furthermore, asymmetric rolling increases the rolling difficulty, makes the sheet shape uncontrollable, and easily leads to problems such as sheet warping, affecting subsequent stamping and other processes.

[0215] 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.

[0216] 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 composite material comprising an aluminum layer and a copper layer on the surface of the aluminum layer; the thickness ratio of the copper layer to the aluminum layer is 1:(2~10); the thickness of the copper layer is 10μm~25μm; a copper-aluminum intermetallic compound layer is present 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 composite material; the thickness of the copper-aluminum intermetallic compound layer is 1μm~3μm.

2. The composite material according to 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 composite material.

3. The 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 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 composite material according to any one of claims 1 to 4, wherein, The copper layer is brass, and the thickness of the copper layer is 15μm~25μm.

6. The composite material according to any one of claims 1 to 4, wherein, The copper layer is made of pure copper, and the thickness of the copper layer is 10μm~20μm.

7. The composite material according to any one of claims 1 to 6, wherein, It includes two copper layers, which are located on two opposite sides of the aluminum layer.

8. The composite material according to claim 7, wherein, The thickness ratio of the two copper layers is 1:(0.5~2).

9. The composite material according to any one of claims 1 to 8, wherein, The interfacial shear strength of the composite material is above 100 MPa.

10. The composite material according to any one of claims 1 to 9, wherein, The conductivity of the composite material is 85% to 90% of that of pure aluminum.

11. The composite material according to any one of claims 1 to 10, wherein, The elongation of the composite material is 7% to 9%.

12. A method for preparing a 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 material is subjected to a first annealing treatment; The first composite plate after the first annealing treatment 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 a second annealing treatment.

13. The method for preparing the composite material according to claim 12, wherein, The temperature of the first rolling process is 380℃~420℃.

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

15. The method for preparing the composite material according to any one of claims 12 to 14, wherein, The first rolling process is a single pass.

16. The method for preparing the composite material according to any one of claims 12 to 15, wherein, The temperature of the first annealing treatment is 300℃~420℃.

17. The method for preparing the composite material according to any one of claims 12 to 16, wherein, The first annealing process takes 2 to 30 minutes.

18. The method for preparing the composite material according to any one of claims 12 to 17, wherein, The temperature for the second annealing treatment is 180℃~250℃.

19. The method for preparing the composite material according to any one of claims 12 to 18, wherein, The second annealing process takes 0.5 hours to 2 hours.

20. The method for preparing the composite material according to any one of claims 12 to 19, wherein, Along the first direction, the width of the groove is 15μm~30μm.

21. The method for preparing the composite material according to any one of claims 12 to 20, wherein, Along the first direction, the spacing between two adjacent grooves is 30μm to 100μm.

22. The method for preparing the composite material according to any one of claims 12 to 21, wherein, The depth of the trench is 8μm~12μm.

23. The method for preparing the composite material according to any one of claims 12 to 22, wherein, The second rolling temperature is 250℃~350℃, and the second rolling includes: The first composite plate is subjected to one or two first sub-rolling passes to make the copper layer reach a first preset thickness, and the deformation of each first sub-rolling pass is 20% to 35%. The first composite plate after the first sub-rolling is subjected to multiple passes of second sub-rolling, with the deformation amount of each second sub-rolling decreasing sequentially, and the deformation amount of each second sub-rolling being less than 20%, so that the copper layer reaches a second preset thickness, which is 10μm~25μm.

24. The method for preparing the composite material according to claim 23, wherein, The ratio of the first preset thickness to the second preset thickness is 1:(1.1~1.3).

25. The method for preparing the composite material according to any one of claims 12 to 24, wherein, Before stacking the copper plate and the aluminum plate, the following steps are also included: The surfaces of the copper plate and the aluminum plate having the grooves are roughened to make the surface roughness Ra of the copper plate and the aluminum plate having the grooves 1μm~6μm.

26. The method for preparing the composite material according to claim 25, wherein, The surfaces of the copper plate and the aluminum plate with the grooves are roughened using a wire brush and abrasive putty; the wire diameter of the wire brush is 0.08mm~0.12mm; the abrasive putty includes a plastic matrix and silicon carbide abrasive.

27. An LED bracket comprising the composite material according to any one of claims 1 to 11, or the composite material prepared by the method of preparing the composite material according to any one of claims 12 to 26.

28. A method for preparing an LED bracket, comprising the following steps: The composite material is prepared using the method for preparing the composite material according to any one of claims 12 to 26; The composite material is subjected to stamping and stretching, electroplating, injection molding, silver plating bending, die bonding and adhesive application, and lead welding in sequence.

29. The method for preparing an LED bracket according to claim 28, wherein, The stamping speed for the stamping and stretching process is 300 times / minute to 700 times / minute.

30. The method for preparing an LED bracket according to claims 28-29, wherein, The electroplating includes the following steps: pre-plating a copper plating layer with a thickness of 0.5μm to 0.6μm, plating a nickel plating layer with a thickness of 0.5μm to 0.6μm on the copper plating layer, and plating a silver plating layer with a thickness of 0.35μm to 0.38μm on the nickel plating layer.

31. The method for preparing an LED bracket according to any one of claims 28 to 30, wherein, The temperature of the injection mold is 100℃~140℃.

32. The method for preparing an LED bracket according to any one of claims 28 to 31, wherein, The injection pressure for the injection molding process is 80MPa~120MPa.

33. The method for preparing an LED bracket according to any one of claims 28 to 32, wherein, The holding time for injection molding is 5s to 10s.

34. The method for preparing an LED bracket according to any one of claims 28 to 33, wherein, The cooling time for the injection molding is 10s to 20s.

35. The method for preparing an LED bracket according to any one of claims 28 to 34, wherein, During the bending of the silver-plated feet, the bending angle deviation is controlled within ±10°.

36. The method for preparing an LED bracket according to any one of claims 28 to 35, wherein, The curing temperature of the die-bonding adhesive is 180℃~200℃.

37. The method for preparing an LED bracket according to any one of claims 28 to 36, wherein, The curing time of the die-bonding adhesive is 110 min to 130 min.

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