A multi-faceted composite copper-aluminum substrate, a copper-aluminum composite heat dissipation device and a manufacturing method

Abstract

The present application relates to a kind of multi-faceted composite copper-aluminum substrate, copper-aluminum composite heat dissipation device and manufacturing method, multi-faceted composite copper-aluminum substrate includes aluminum plate and copper plate, copper plate is formed with continuous copper-aluminum diffusion layer between the aluminum plate;Copper-aluminum diffusion layer includes bottom bonding area combined in up-down direction and side bonding area combined in horizontal direction.Copper-aluminum composite heat dissipation device includes multi-faceted composite copper-aluminum substrate and several heat sinks.Process includes: the fourth surface of copper plate is placed on the first surface of aluminum plate;Copper plate and aluminum plate are welded together using diffusion welding, to obtain copper-aluminum bonding plate, form continuous copper-aluminum diffusion layer;Copper-aluminum bonding plate is placed into forging die, and the copper material of upper die is embedded in the first surface of aluminum plate in the corresponding position of boss, to obtain forging piece.The present application uses diffusion welding as the basis of copper-aluminum composite, and the boss forging forms the bonding structure of five faces, which greatly improves the bonding capacity of copper plate and aluminum plate.

Description

Technical Field

[0001] This invention relates to the field of thermal management device manufacturing technology, and in particular to a multi-faceted composite copper-aluminum substrate, a copper-aluminum composite heat dissipation device, and a manufacturing method thereof. Background Technology

[0002] As a crucial heat dissipation device for heat-generating electronic components in electrical appliances, the selection of materials for heat sinks requires comprehensive consideration of factors such as thermal conductivity, corrosion resistance, density, and cost. While pure copper has high thermal conductivity and is easy to directly solder to power devices, its application in water-cooled products presents challenges such as poor corrosion resistance requiring additional electroplating, high density, and high unit price. Aluminum, on the other hand, has low density and good corrosion resistance (requiring only simple passivation), but its thermal conductivity is relatively poor. To balance lightweight design with high thermal conductivity, copper-aluminum composite structures have become an effective solution; however, achieving a strong bond at the copper-aluminum interface while maintaining structural stability remains a technical challenge.

[0003] In existing technologies, the design and manufacturing processes of various copper-aluminum composite heat sinks still suffer from insufficient bonding strength or structural reliability issues. For example, the high thermal conductivity copper-aluminum composite round pin heat sink disclosed in Chinese patent CN213811924U uses an aluminum plate and a copper plate to form a composite base through face-to-face cold forging. However, due to the inherent lack of good compatibility between copper and aluminum, it is difficult to achieve a strong interface bond through cold forging alone. Especially when manufacturing products with curved surfaces, the deformation stress generated by the subsequent arc pressing process can easily lead to separation of the copper-aluminum interface, failing to meet the bonding strength requirements against separation in practical applications.

[0004] Another patent, CN103499077A, proposes a copper-aluminum composite LED heat sink. It involves creating a pre-pressed groove in the aluminum heat sink body, embedding a heat-conducting copper sheet with an interference fit, and then forging the two together. The drawback of this method is that the interference fit causes the copper sheet to continuously apply lateral pressure to the sidewall of the pre-pressed groove. The residual internal stress after forging will cause the aluminum body to bend in the opposite direction, affecting the overall structural stability and shape accuracy of the heat sink. Furthermore, the copper and aluminum plates are only securely connected through the interference fit between the copper block and the groove on the aluminum plate; there is no material bonding force between the copper and aluminum plates, resulting in poor adhesion.

[0005] Furthermore, patent CN120587854A employs a diffusion welding process to enhance the bond strength between copper and aluminum. The steps include embedding a copper plate into a groove or through-groove in an aluminum plate to form a double-layer plate, followed by diffusion welding, and then extrusion and stretching. Although diffusion welding can achieve atomic-level diffusion bonding in a vacuum or protective atmosphere through heating and pressurization, in this design, the copper plate is primarily embedded within the aluminum plate groove, and the welding pressure mainly acts vertically. This results in a relatively reliable bond between the bottom of the groove and the copper plate, but significantly weakens the diffusion welding effect between the sidewalls of the groove and the copper plate. This leads to insufficient sidewall connection strength, affecting not only the overall mechanical bonding strength but also potentially forming an interface layer with high thermal resistance, thereby reducing the heatsink's thermal conductivity.

[0006] In summary, existing copper-aluminum composite heat sinks still face the following key challenges in interface bonding processes: cold forging is insufficient to overcome the poor material compatibility leading to easy interface separation; interference fits and forging combinations easily introduce internal stress, causing structural deformation; diffusion welding in embedded designs suffers from uneven pressure distribution, limiting the strength and thermal conductivity of sidewall connections. Therefore, there is an urgent need for a composite heat sink manufacturing method that can achieve uniform bonding of copper and aluminum in all directions, controllable stress, and structural stability. Summary of the Invention

[0007] The first main objective of this invention is to provide a multi-faceted composite copper-aluminum substrate that, by setting a continuous copper-aluminum diffusion layer, not only combines the high thermal conductivity of copper and the corrosion resistance of aluminum, but also improves the ability of the copper plate to connect with the aluminum plate in five directions, thereby enhancing the connection strength.

[0008] This invention achieves the above objective through the following technical solution: a multi-sided composite copper-aluminum substrate, comprising:

[0009] An aluminum sheet having a first surface and a second surface that are opposite each other.

[0010] A copper plate has a third surface and a fourth surface that are opposite each other. The fourth surface of the copper plate is attached to the first surface of the aluminum plate and embedded downward on the first surface of the aluminum plate. A continuous copper-aluminum diffusion layer is formed between the surfaces of the copper plate and the aluminum plate. The copper-aluminum diffusion layer includes a bottom bonding region that is bonded in the vertical direction and a side bonding region that is bonded in the horizontal direction. The thickness of the copper-aluminum diffusion layer ranges from 200 nm to 2 μm.

[0011] Specifically, the bottom bonding area and the side bonding area are smoothly connected, and the vertical cross-section of the side bonding area is C-shaped, surrounding the side of the copper plate.

[0012] Specifically, multiple copper plates are embedded on the first surface of the aluminum plate.

[0013] Specifically, the multi-faceted composite copper-aluminum substrate has a curved shape.

[0014] The second main objective of this invention is to provide a copper-aluminum composite heat dissipation device that combines a multi-faceted composite copper-aluminum substrate with a heat sink to form a combination with high thermal conductivity and good corrosion resistance, thereby improving overall performance.

[0015] The present invention achieves the above objective through the following technical solution: a copper-aluminum composite heat dissipation device, comprising the multi-faceted composite copper-aluminum substrate and a plurality of heat sinks, wherein the heat sinks are connected to the second surface of the aluminum plate, and the heat sinks are heat dissipation pins, heat dissipation fins or heat dissipation channels.

[0016] The third main objective of this invention is to provide a method for manufacturing a multi-sided composite copper-aluminum substrate. This method utilizes diffusion welding technology to weld copper and aluminum plates together, followed by forging within the copper-aluminum hybrid layer, to achieve efficient processing of the composite structure. The core of this technology lies in the continuity of the copper-aluminum hybrid layer and the thickness of the copper-aluminum diffusion layer, ensuring the stability and excellent performance of the composite material and solving the problem of difficult processing of traditional single-sided materials.

[0017] This invention achieves the above objective through the following technical solution: a method for manufacturing a multi-sided composite copper-aluminum substrate, comprising:

[0018] The fourth surface of the copper plate is attached to the first surface of the aluminum plate;

[0019] The copper plate and the aluminum plate are welded together by diffusion welding to obtain a copper-aluminum composite plate, and a continuous copper-aluminum diffusion layer is formed between the surfaces of the copper plate and the aluminum plate that are in contact.

[0020] With the first surface of the aluminum plate facing upwards, the copper-aluminum bonding plate is placed in a forging die. The upper die of the forging die is provided with a boss corresponding to the position of the copper plate. The upper die causes the copper material at the position corresponding to the boss to be embedded in the first surface of the aluminum plate to obtain a forging. The copper-aluminum diffusion layer is then forged to form the bottom bonding area and the side bonding area.

[0021] Specifically, the horizontal cross-sectional area of ​​the copper plate is larger than the horizontal cross-sectional area of ​​the boss, and the copper-aluminum diffusion layer retains a horizontal bonding area that is not squeezed by the boss during the forging process, and the horizontal bonding area is adjacent to the side bonding area.

[0022] Furthermore, the process also includes milling the surface of the forged part where the copper plate is embedded to remove the horizontal bonding area, thereby obtaining the multi-faceted composite copper-aluminum substrate.

[0023] Furthermore, it also includes pressing the surface of the multi-faceted composite copper-aluminum substrate into an arc-shaped structure.

[0024] Specifically, the lower die of the forging die is provided with several forming holes. The upper die causes the copper material at the corresponding position of the boss to be embedded in the aluminum plate, while the material of the aluminum plate flows into the forming holes to form a heat sink. Then, the upper end of the heat sink is cut flat to a uniform height.

[0025] The beneficial effects of the technical solution of this invention are:

[0026] 1) By first diffusion welding the copper plate and aluminum plate together, and then using boss forging to squeeze the copper plate into the aluminum plate, unlike the traditional approach of "first slotting and embedding, and then trying to combine", a new manufacturing path of "first combining in the whole area, and then plastic forming" is adopted to ensure that a strong, full-coverage atomic-level connection has been established between the two materials, copper and aluminum, before any complex deformation occurs.

[0027] 2) First, diffusion welding provides the "quality" of the connection (high-strength metallurgical bonding), while boss forging provides the "form" of the connection (three-dimensional encapsulated interlocking structure) and "stress management" (smooth transition interface). The two are not simply superimposed, but produce a synergistic effect of "1+1>2".

[0028] 3) By forming a copper-aluminum diffusion layer consisting of a bottom bonding area and a side bonding area at the interface where the copper plate and aluminum plate are bonded, a multi-faceted bond between the copper plate and aluminum plate is formed, which greatly improves the bonding ability between the copper plate and aluminum plate compared to the pure bottom bonding area in the original structure.

[0029] 4) By forming a C-shaped covering structure in the side panel bonding area, a mechanical anchoring structure is formed for the internal copper plate in the vertical direction, which realizes the strong wrapping of the aluminum plate on the outer periphery of the copper plate side panel, further improving the bonding ability between the copper plate and the aluminum plate.

[0030] 5) The interface formed by full-area diffusion welding, boss forging, and C-shaped side wrapping has the metallurgical bonding force of the diffusion layer, the stress buffering capacity of the C-shaped interface, and the mechanical anchoring force of the aluminum wrapping on the upper side. It ensures the ultimate reliability and long-term stability of the connection from multiple dimensions, with reasonable internal stress distribution, and can even adapt to the manufacturing requirements of the special curvature of the product. Attached Figure Description

[0031] Figure 1 This is a cross-sectional view of the multi-faceted composite copper-aluminum substrate of Example 1;

[0032] Figure 2 This is a cross-sectional view showing the manufacturing method of the multi-faceted composite copper-aluminum substrate in Example 1.

[0033] Figure 3 This is a cross-sectional view of the multi-faceted composite copper-aluminum substrate of Example 1;

[0034] Figure 4 This is a cross-sectional view of the copper-aluminum composite heat dissipation device in Example 2;

[0035] Figure 5 This is a perspective view of the copper-aluminum composite heat dissipation device in Example 2;

[0036] Figure 6 This is a perspective view of the copper-aluminum composite heat dissipation device in Example 2 from another angle;

[0037] Figure 7 This is a cross-sectional view showing the manufacturing method of the copper-aluminum composite heat dissipation device in Example 2;

[0038] Figure 8 This is a cross-sectional schematic diagram of the copper-aluminum composite heat dissipation device in Example 3.

[0039] The diagram is marked as follows:

[0040] 1-Multi-sided composite copper-aluminum substrate, 1a-Copper-aluminum bonding plate, 1b-Forged part, 10-Copper-aluminum composite heat dissipation device;

[0041] 11-Copper plate, 111-Copper face, 12-Aluminum plate, 121-Heat sink, 13-Copper-aluminum diffusion layer, 131-Bottom bonding area, 132-Side bonding area, 133-Horizontal bonding area;

[0042] 20-Forging die, 21-Lower die, 211-Forming hole, 22-Upper die, 221-Boss. Detailed Implementation

[0043] This solution aims to address three core defects in the manufacturing of existing copper-aluminum composite radiators:

[0044] 1) Weak interfacial bonding and easy separation: As described in patent CN213811924U, simple cold forging cannot overcome the fundamental problem of poor compatibility between copper and aluminum materials, and the interface is easy to separate during subsequent deformation (such as arc pressing).

[0045] 2) Internal stress concentration leads to structural deformation: As described in patent CN103499077A, the interference fit + forging method will leave uneven transverse internal stress in the aluminum matrix, causing the heat sink body to bend in the opposite direction and fail to meet the structural accuracy requirements.

[0046] 3) Uneven diffusion welding pressure, poor lateral connection and heat conduction: As described in patent CN120587854A, when the copper plate is embedded in the groove of the aluminum plate and diffusion welding is performed, the vertical pressure is difficult to effectively act on the side wall, resulting in the lateral bonding force and heat conduction performance becoming a weakness.

[0047] The present invention will be further described in detail below with reference to specific embodiments.

[0048] Example 1: Multi-faceted composite copper-aluminum substrate 1

[0049] like Figure 1 As shown, a multi-faceted composite copper-aluminum substrate 1 includes an aluminum plate 12 and several copper plates 11. The aluminum plate 12 has a first surface and a second surface that are vertically opposite each other, and the copper plates 11 have a third surface and a fourth surface that are vertically opposite each other. The fourth surface of the copper plate 11 is attached to the first surface of the aluminum plate 12 and embedded downward on the first surface of the aluminum plate 12. A continuous copper-aluminum diffusion layer 13 is formed between the copper plate 11 and the aluminum plate 12. A copper-aluminum diffusion layer 13 with a thickness of 200nm-2um is formed between each copper plate 11 and the aluminum plate 12. The copper-aluminum diffusion layer 13 includes a bottom bonding region 131 that is bonded vertically and a side bonding region 132 that is bonded horizontally.

[0050] The irregular structure of the copper-aluminum diffusion layer 13 is due to the manufacturing process. By using an aluminum-clad copper substrate, aluminum, due to its rapid passivation, exhibits greater oxidation resistance than copper. Aluminum has a lower density and is cheaper than copper, thus providing corrosion protection, weight reduction, and cost reduction. Therefore, the multi-faceted composite copper-aluminum substrate 1 combines the high thermal conductivity of copper with the low density of aluminum, fundamentally reducing the overall weight of the substrate and making it more suitable for the lightweight market. Utilizing the passivation properties of aluminum in air, the copper material is protected on the inside, preventing oxidation and eliminating the need for large-area electroplating, thereby reducing process costs. Replacing some copper material with inexpensive aluminum reduces material costs without changing the overall volume.

[0051] At the same time, the continuous copper-aluminum diffusion layer 13 enables the copper plate 11 to have atomic-level connections with the aluminum plate 12 in five directions around it, eliminating clear interfaces at the microscopic level and realizing metallurgical bonding between atoms. This fundamentally provides a connection strength far exceeding that of mechanical interlocking, laying a solid foundation.

[0052] like Figure 1 and Figure 3 As shown, the bottom bonding area 131 and the side bonding area 132 transition smoothly, and the vertical cross section of the side bonding area 132 is C-shaped, surrounding the side of the copper plate 11.

[0053] The C-shaped structure of the side-wall bonding area 132 is actually a smooth structure. The smooth transition structure on the copper-aluminum diffusion layer 13 allows the bonding force between the copper and aluminum to change gradually. This prevents sudden changes in internal stress at the microstructure level, thus reducing the risk of springback deformation. The internal stress distribution is reasonable and can even adapt to the manufacturing requirements of the product's special curvature. The upper section of the side-wall bonding area 132 actually wraps around the edge of the copper plate 11, forming a mechanical bonding force at the macroscopic level, further improving the stability of the copper-aluminum bond. The C-shaped smooth interface (without sharp corners or steps) is a continuous transition structure mechanically. When the composite material is heated or stressed, the shear stress generated between the copper and aluminum due to the difference in thermal expansion coefficients, as well as residual processing stress, can be gradually transmitted and dissipated along this smooth path, without concentrating at sharp corners, thus effectively suppressing overall warping or springback deformation.

[0054] like Figure 1 As shown, three copper plates 11 are embedded on the first surface of the aluminum plate 12. In practical applications, the number of copper plates 11 is not limited.

[0055] When the area of ​​the aluminum plate 12 is large, this arrangement can make the area of ​​each copper plate 11 relatively small, and each copper plate 11 can provide greater lateral bonding force near the side joint area 132, which not only makes the structure stable, but also facilitates manufacturing.

[0056] like Figure 2 As shown, a method for manufacturing a multi-faceted composite copper-aluminum substrate 1 includes:

[0057] 1) Process copper plate 11 and aluminum plate 12 of preset dimensions, wherein the area of ​​copper plate 11 is not greater than the area of ​​aluminum plate 12. Aluminum plate 12 has a first surface and a second surface that are opposite each other, and copper plate 11 has a third surface and a fourth surface that are opposite each other. Place the fourth surface of copper plate 11 onto the first surface of aluminum plate 12.

[0058] Both the copper plate 11 and the aluminum plate 12 are regular shapes—rectangular flat plates—providing a large surface area for welding them together. Since the final structure is an aluminum-clad copper structure (aluminum provides corrosion protection for the copper), and the copper plate 11 is to be embedded in sections within the aluminum plate 12, the area of ​​the copper plate 11 is typically smaller than that of the aluminum plate 12. Furthermore, because the edge material of the copper plate 11 may eventually be removed by machining, its initial area only needs to cover more than 80% of the surface of the aluminum plate 12 to meet the requirements of subsequent structural processing and avoid material waste.

[0059] 2) The copper plate 11 and the aluminum plate 12 are welded together by diffusion welding to obtain a copper-aluminum composite plate 1a, and a continuous copper-aluminum diffusion layer 13 is formed between the copper plate 11 and the aluminum plate 12.

[0060] Copper and aluminum are inherently poorly compatible, with weak interfacial bonding. Diffusion welding, a solid-state welding process that achieves material bonding through atomic diffusion, does not require melting the base material. It relies primarily on pressure, temperature, and time to drive atomic migration, ultimately forming a metallurgical bond. During diffusion welding, the pressure mainly comes from the vertical direction, allowing the entire copper-aluminum diffusion layer 13 to achieve a relatively stable interlayer compatibility structure under relatively uniform pressure, thus achieving a seamless and complete connection between the two materials.

[0061] The principle of diffusion welding is as follows:

[0062] Phase 1: Surface Contact and Deformation

[0063] Applying pressure causes the surfaces to be welded to come into close contact, and the micro-protrusions undergo plastic deformation, removing the surface oxide film and adsorption layer, expanding the contact area from point contact to surface contact (the actual contact area needs to reach more than 80%).

[0064] Phase 2: Interface Diffuse Initiation

[0065] Heat to 0.5-0.8T on the base material. m (Melting point, absolute temperature), atomic thermal motion intensifies:

[0066] Short-range diffusion: Vacancy migration at the interface forms an initial diffusion layer (approximately 1-10 μm thick).

[0067] Grain boundary diffusion: Atoms migrate 10 times faster along grain boundaries than within the lattice. 3 -10 6 The number of times is the main channel for diffusion.

[0068] Stage 3: Pore Elimination and Diffusion Layer Growth

[0069] The tiny pores remaining at the interface gradually close through volume diffusion (atomic filling) and grain boundary slip, and the diffusion layer grows towards the parent material on both sides, with elements interpenetrating to form solid solutions or intermetallic compounds.

[0070] Phase 4: Metallurgical integration completed

[0071] The copper-aluminum diffusion layer 13 has a thickness of 200nm-2µm, achieving atomic-level bonding and forming a thin layer dominated by solid solution. Interfaces disappear, and the joint strength approaches that of the base material, achieving a seamless connection. This copper-aluminum diffusion layer 13 can provide a connection strength >10MPa. This layer eliminates clear interfaces at the microscopic level, achieving metallurgical bonding between atoms, fundamentally providing a connection strength far exceeding that of mechanical interlocking, making the copper and aluminum appear "as one" during subsequent deformation.

[0072] Therefore, the copper-aluminum composite plate 1a will be a double-layer plate with different metals tightly attached together. This structure is relatively simple, but it can ensure good connection strength between copper and aluminum.

[0073] 3) With the first surface of the aluminum plate 12 facing upwards, the copper-aluminum bonding plate 1a is placed into the forging die. The upper die 22 of the forging die 20 is provided with a boss 221 corresponding to the position of the copper plate. The upper die 22 causes the copper material at the position corresponding to the boss 221 to be embedded in the first surface of the aluminum plate 12, resulting in a forged part 1b. The copper-aluminum diffusion layer 13 is then forged to form a bottom bonding area 131 and a side bonding area 132. The horizontal cross-sectional area of ​​the copper plate 11 is larger than the horizontal cross-sectional area of ​​the boss 221. During the forging process, the copper-aluminum diffusion layer 13 retains a horizontal bonding area 133 that is not squeezed by the boss 221. The horizontal bonding area 133 is adjacent to the side bonding area 132. The forging pressure is 10-2000t, the forging temperature is 20-350℃, and the plate stretching length is 1-10mm.

[0074] The most important purpose of forging in this process is to create an aluminum-clad copper structure on one side of the copper plate 11, but not a sharply defined structure. Because the boss 221 exerts greater pressure on the copper plate 11 than other parts of the upper die 22 under the same stroke, the forging pressure is actually concentrated at the boss 221, forcibly squeezing the contact area between the copper plate 11 and the boss 221 into the aluminum plate 12, naturally forming an embedded structure. During the entire forging process, the thickness of the copper-aluminum bonding plate 1a decreases, and both materials are stretched together. While maintaining the welding relationship, the five surfaces of the inwardly protruding copper material (i.e., the bottom bonding area 131 and the four side bonding areas 132) are tightly wrapped by the aluminum material. Unlike the method of first slotting and then embedding, the five bonding areas mentioned above are originally on the same surface. The bottom bonding area 131 and the four side bonding areas 132 are all formed by the compression deformation of the flat copper-aluminum diffusion layer 13. The bonding force generated by diffusion welding is retained along the direction perpendicular to the interface. The copper-aluminum diffusion layer 13 will hold the copper and aluminum materials on both sides. Under the huge forging pressure, the copper-aluminum bonding plate 1a is plastically deformed as a whole with the copper-aluminum diffusion layer 13 as the link. Therefore, the connection position between the bottom bonding area 131 and the side bonding area 132 after deformation is a smooth transition. The aluminum material squeezed by the boss 221 will flow to the side where the copper is embedded. The aluminum material directly opposite the boss 221 can only move to the sides to form the bottom bonding area 131. Therefore, the bottom bonding area 131 can present a relatively flat state. However, the side bonding areas 132 even flip up above the copper and present a curved structure (C-shaped structure), forming a three-dimensional interlocking structure and generating a strong mechanical anchoring effect.

[0075] Because the heat dissipation requirements at different copper facets 111 may vary, and the thickness of the copper facet 111 depends on the height of the boss 221, the heights of different bosses 221 can be the same or different. Multiple copper materials can be embedded on the first surface of the aluminum plate 12, the number corresponding to the number of bosses 221. The copper material at each location is joined on five sides, adapting to various sizes of copper-aluminum composite requirements. The thickness of the copper material can be selected from 0.1-6mm.

[0076] 4) The surface of the forged part 1b in which the copper plate 11 is embedded is milled flat, and the horizontal bonding area 133 is removed to obtain the multi-faceted composite copper-aluminum substrate 1. The remaining thickness of the copper material is 0.05-2.5mm (thickness of the copper surface 111).

[0077] On the forged part 1b, the first surface of the aluminum plate 12 is covered by a copper plate 11 of uneven thickness, and the back structure of the forged part 1b is also uneven. Although the copper-aluminum interface is irregular from the internal cross-section, most applications require a regular structure on the back. Moreover, in non-critical areas, the aluminum material needs to surround the copper material to achieve corrosion protection. Therefore, the copper-embedded surface of the forged part 1b needs to be milled flat. Milling retains the copper material embedded in the aluminum plate 12, removes redundant copper material in non-functional areas, and exposes the corrosion-resistant aluminum material, further optimizing weight and cost.

[0078] Figure 3 This shows the actual situation of a slice of this multi-faceted composite copper-aluminum substrate 1 along its thickness. The six points are all located on the copper-aluminum diffusion layer 13, vaguely forming a curved, blurred dividing line. It can be seen that the material in the lower left corner of the copper-aluminum diffusion layer 13 is whitish, indicating aluminum, while the material in the upper right corner is reddish, indicating copper. Because the copper-aluminum diffusion layer 13 is a thin interface formed by the mutual diffusion of copper and aluminum, it appears blurred and without obvious seams on the cross-section. This curved interface is due to the copper material being squeezed into the aluminum plate 12 during the forging process, and the copper-aluminum diffusion layer 13 pulling the materials on both sides together during deformation.

[0079] The thickness of the copper-aluminum diffusion layer 13 at these 6 points was measured using a microscope. Each point was measured three times, and the measured values ​​are shown in Table 1.

[0080] Table 1: Unit: nm

[0081]

[0082] The shape of this copper-aluminum diffusion layer 13 is the result of both diffusion welding and forging. The thickness resulting from diffusion welding is between 200nm and 2um and is relatively uniform, but the uniformity of the thickness changes after forging. Positions 5 and 6 are basically in the positive position of the boss 221 (belonging to the bottom bonding area 131), so the copper-aluminum diffusion layer 13 will be squeezed tightly, and therefore the thickness here will be relatively small; positions 1 and 2 are at the upper end of the side bonding area 132, and will be squeezed downward by other positions of the upper die 22 during forging, so the thickness will also be slightly reduced, but slightly thicker than positions 5 and 6; positions 3 and 4 are on the side of the material flow direction and are not subjected to a large positive extrusion force, so the thickness is relatively thick.

[0083] Example 2: Flat-surfaced copper-aluminum composite heat dissipation device 10

[0084] like Figures 3 to 6 As shown, the difference from Embodiment 1 is that: in the forging step, the lower die 21 of the forging die 20 is provided with a plurality of forming holes 211, and the upper die 22 causes the copper material at the corresponding position of the boss 221 to be embedded into the aluminum plate 12, while the surface material of the aluminum plate 12 flows into the forming holes 211 to form a heat sink 121. The heat sink 121 is a heat dissipation pin that is evenly distributed on the surface of the aluminum plate 12.

[0085] The multi-faceted composite copper-aluminum substrate 1 is the basic structure of the copper-aluminum composite heat dissipation device 10. The heat sink 121 can increase the specific surface area and can be used in water-cooled boxes. Its flat back side (copper-embedded surface) is used to absorb heat, while the front side carries away heat through flowing cooling water, thus achieving a heat dissipation effect. The heat sink 121 is mostly located within the upper projection range of the copper surface 111. Due to its location, the copper surface 111 can conduct heat laterally, and the heat sink 121 can conduct heat longitudinally. In this way, the shortest path for heat conduction from the copper surface 111 to the heat sink 121 will always pass through the copper surface 111 first, and then through the aluminum heat sink 121, thus making fuller use of the high thermal conductivity of copper. In practical applications, the structure of the heat sink can also adopt a circular, teardrop, plum blossom, or various convex polygonal structures. Similarly, when the cross-section of the forming hole 211 is a long and narrow structure, the heat sink 121 can also be a flat or curved heat dissipation fin.

[0086] like Figure 6 As shown, the manufacturing method of the copper-aluminum composite heat dissipation device 10 in Example 2 includes:

[0087] 1) Process copper plate 11 and aluminum plate 12 of preset size. The area of ​​copper plate 11 is not greater than the area of ​​aluminum plate 12. Aluminum plate 12 has a first surface and a second surface that are opposite each other. Copper plate 11 has a third surface and a fourth surface that are opposite each other. Place the fourth surface of copper plate 11 on the first surface of aluminum plate 12.

[0088] 2) The copper plate 11 and the aluminum plate 12 are welded together by diffusion welding to obtain a copper-aluminum composite plate 1a, and a continuous copper-aluminum diffusion layer 13 is formed between the copper plate 11 and the aluminum plate 12.

[0089] 3) With the first surface of the aluminum plate 12 facing upward, the copper-aluminum bonding plate 1a is placed in the forging die. The upper die 22 of the forging die 20 is provided with a boss 221 corresponding to the position of the copper plate. The upper die 22 causes the copper material at the position corresponding to the boss 221 to be embedded in the first surface of the aluminum plate 12 and causes the material of the second surface of the aluminum plate 12 to flow into the forming hole 211 to form a heat sink 121, thus obtaining the forging part 1b. The copper-aluminum diffusion layer 13 is then forged to form the bottom bonding area 131 and the side bonding area 132. During the forging process, the copper-aluminum diffusion layer 13 retains a horizontal bonding area 133 that is not squeezed by the boss 221. The horizontal bonding area 133 is adjacent to the side bonding area 132.

[0090] 4) Cut the top of the heat sink 121 flat until it is the same height;

[0091] 5) The surface of the forged part 1b in which the copper plate 11 is embedded is milled flat, and the horizontal bonding area 133 is removed to obtain a copper-aluminum composite heat dissipation device 10 with a flat plate surface. The copper-aluminum composite heat dissipation device 10 includes a multi-faceted composite copper-aluminum substrate 1 and several heat sinks 121. The heat sinks 121 are connected to the second surface of the aluminum plate 12. The back side of the multi-faceted composite copper-aluminum substrate 1 includes multiple copper face surfaces 111 surrounded by aluminum material.

[0092] Another purpose of forging is to create a heat sink 121 on the second surface of the aluminum plate 12. Given the limited space within the forging die 20, excess material from one side of the aluminum plate 12 flows into the forming hole 211, thus forming the heat sink 121. The heat sink 121 is a structure used to increase the heat exchange area. In Embodiment 1, the cross-section of the heat sink pin is elliptical because forging allows material to flow into the channel formed by the forming hole 211, subsequently growing into a needle-shaped or cylindrical heat sink 121, which is the heat sink pin. In practical applications, the heat sink pin can also be replaced by heat dissipation fins (elongated cross-section structure) or heat dissipation channels (labyrinthine structure). Both heat sink pins and heat dissipation fins can be evenly distributed on the second surface of the aluminum plate 12.

[0093] The heat sink 121 (needle) is extruded during forging and is integrally formed on the second surface of the aluminum plate 12. During forging, the flat blank is squeezed by the die, and the metal flows in the direction of least resistance. The middle area is more constrained by both the upper and lower dies, making it difficult for the material to expand outward, resulting in limited space for the needle to "grow taller"; while the surrounding areas are only constrained by a die on one side, allowing the metal to flow freely outward, making it easier to form a longer needle. This results in the natural forging process having a shorter needle in the middle and a longer needle on the periphery. To make heat dissipation more uniform, the extra height of the needles on the periphery compared to the middle needle needs to be trimmed. The final result is a copper-aluminum composite heat sink 10 with a flat plate surface.

[0094] Example 3: Copper-aluminum composite heat dissipation device with curved plate surface 10

[0095] like Figure 7 As shown, the difference from Example 2 is that the multi-faceted composite copper-aluminum substrate 1 has an arc that makes the copper plate embedded in the surface concave.

[0096] In tablet devices (such as mobile phones and computers), the core heat-generating components (chips, processors) are usually located in the center. However, with increasing design complexity, many heat dissipation products require a slight curvature on the board surface. In Example 3, the multi-faceted composite copper-aluminum substrate 1 undergoes all the processing steps of Example 2 to obtain a flat product board with relatively uniform internal stress. Therefore, while ensuring the heat sink 121 and the board surface thickness are uniform, sometimes it is necessary to process the copper-aluminum composite heat dissipation device 10 into a slightly convex arc-shaped structure in the middle. The structure of the copper-aluminum composite heat dissipation device 10 can be applied to the flat or pin-shaped plates of semiconductor modules.

[0097] like Figure 7 As shown, the manufacturing method of the copper-aluminum composite heat dissipation device 10 in Example 3 includes:

[0098] 1) Process copper plate 11 and aluminum plate 12 of preset size. The area of ​​copper plate 11 is not greater than the area of ​​aluminum plate 12. Aluminum plate 12 has a first surface and a second surface that are opposite each other. Copper plate 11 has a third surface and a fourth surface that are opposite each other. Place the fourth surface of copper plate 11 on the first surface of aluminum plate 12.

[0099] 2) The copper plate 11 and the aluminum plate 12 are welded together by diffusion welding to obtain a copper-aluminum composite plate 1a, and a continuous copper-aluminum diffusion layer 13 is formed between the copper plate 11 and the aluminum plate 12.

[0100] 3) With the first surface of the aluminum plate 12 facing upward, the copper-aluminum bonding plate 1a is placed in the forging die. The upper die 22 of the forging die 20 is provided with a boss 221 corresponding to the position of the copper plate. The upper die 22 causes the copper material at the position corresponding to the boss 221 to be embedded in the first surface of the aluminum plate 12 and causes the material of the second surface of the aluminum plate 12 to flow into the forming hole 211 to form a heat sink 121, thus obtaining the forging part 1b. The copper-aluminum diffusion layer 13 is then forged to form the bottom bonding area 131 and the side bonding area 132. During the forging process, the copper-aluminum diffusion layer 13 retains a horizontal bonding area 133 that is not squeezed by the boss 221. The horizontal bonding area 133 is adjacent to the side bonding area 132.

[0101] 4) Cut the top of the heat sink 121 flat until it is the same height;

[0102] 5) Mill the surface of the forged part 1b in which the copper plate 11 is embedded, and remove the horizontal bonding area 133;

[0103] 6) Make the surface of the multi-sided composite copper-aluminum substrate 1 present an arc-shaped structure with the copper plate embedded in the concave surface, and obtain a copper-aluminum composite heat dissipation device 10 with a curved surface.

[0104] The multi-faceted composite copper-aluminum substrate 1 here is also part of the copper-aluminum composite heat dissipation device 10. Based on the original aluminum-clad copper structure, the curved surface of the multi-faceted composite copper-aluminum substrate 1 only causes the aluminum material to compress the edges of the copper material more tightly. However, with the copper-aluminum diffusion layer 13, the internal stress smoothly transitions and is slowly released within the continuous C-shaped interface, avoiding sudden changes in local stress. This allows the composite board to withstand subsequent processing (arc pressing) without easily delaminating.

[0105] In other embodiments, a multi-faceted composite copper-aluminum substrate 1 product with only curvature and no heat sink 121 can also be manufactured. The product can have a structure with an aluminum surface and a copper-embedded surface, or it can have a structure with a concave-convex surface with a heat sink 121 and a flat copper-embedded surface, or it can have a curved board surface, adapting to various places with heat dissipation requirements.

[0106] In summary, this process technology solution is a systematic and innovative approach. Its core innovation lies in:

[0107] 1) By first diffusion welding the copper plate and aluminum plate together, and then using boss forging to squeeze the copper plate into the aluminum plate, unlike the traditional approach of "first slotting and embedding, and then trying to combine", a new manufacturing path of "first combining in the whole area, and then plastic forming" is adopted to ensure that a strong, full-coverage atomic-level connection has been established between the two materials, copper and aluminum, before any complex deformation occurs.

[0108] 2) First, diffusion welding provides the "quality" of the connection (high-strength metallurgical bonding), while boss forging provides the "form" of the connection (three-dimensional encapsulated interlocking structure) and "stress management" (smooth transition interface). The two are not simply superimposed, but produce a synergistic effect of "1+1>2".

[0109] 3) By forming a copper-aluminum diffusion layer consisting of a bottom bonding area and a side bonding area at the interface where the copper plate and aluminum plate are bonded, a multi-faceted bond between the copper plate and aluminum plate is formed, which greatly improves the bonding ability between the copper plate and aluminum plate compared to the pure bottom bonding area in the original structure.

[0110] 4) By forming a C-shaped covering structure in the side panel bonding area, a mechanical anchoring structure is formed for the internal copper plate in the vertical direction, which realizes the strong wrapping of the aluminum plate on the outer periphery of the copper plate side panel, further improving the bonding ability between the copper plate and the aluminum plate.

[0111] 5) The interface formed by full-area diffusion welding, boss forging, and C-shaped side wrapping has the metallurgical bonding force of the diffusion layer, the stress buffering capacity of the C-shaped interface, and the mechanical anchoring force of the aluminum wrapping on the upper side. It ensures the ultimate reliability and long-term stability of the connection from multiple dimensions, with reasonable internal stress distribution, and can even adapt to the manufacturing requirements of the special curvature of the product.

[0112] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A multi-faceted composite copper-aluminum substrate, characterized by: include: An aluminum sheet having a first surface and a second surface that are opposite each other. A copper plate has a third surface and a fourth surface that are opposite each other. The fourth surface of the copper plate is attached to the first surface of the aluminum plate and embedded downward on the first surface of the aluminum plate. A continuous copper-aluminum diffusion layer is formed between the surfaces of the copper plate and the aluminum plate. The copper-aluminum diffusion layer includes a bottom bonding region that is bonded in the vertical direction and a side bonding region that is bonded in the horizontal direction. The thickness of the copper-aluminum diffusion layer ranges from 200 nm to 2 μm. The bottom bonding area and the side bonding area are smoothly connected, and the vertical cross-section of the side bonding area is C-shaped, surrounding the side of the copper plate.

2. The multi-faceted composite copper-aluminum substrate of claim 1, wherein: Multiple copper plates are embedded on the first surface of the aluminum plate.

3. The multi-faceted composite copper-aluminum substrate of claim 1, wherein: The multi-faceted composite copper-aluminum substrate has a curved shape.

4. A copper-aluminum composite heat dissipation device, characterized in that: The invention comprises a multi-faceted composite copper-aluminum substrate as described in any one of claims 1-3 and a plurality of heat sinks, wherein the heat sinks are connected to the second surface of the aluminum plate, and the heat sinks are heat sink pins, heat sink fins or heat sink channels.

5. A method of manufacturing the multi-faceted composite copper-aluminum substrate of any one of claims 1-3, wherein: include: The fourth surface of the copper plate is attached to the first surface of the aluminum plate; The copper plate and the aluminum plate are welded together by diffusion welding to obtain a copper-aluminum composite plate, and a continuous copper-aluminum diffusion layer is formed between the surfaces of the copper plate and the aluminum plate that are in contact. With the first surface of the aluminum plate facing upwards, the copper-aluminum bonding plate is placed in a forging die. The upper die of the forging die is provided with a boss corresponding to the position of the copper plate. The upper die causes the copper material at the position corresponding to the boss to be embedded in the first surface of the aluminum plate to obtain a forging. The copper-aluminum diffusion layer is then forged to form the bottom bonding area and the side bonding area.

6. The manufacturing method according to claim 5, characterized in that: The horizontal cross-sectional area of ​​the copper plate is larger than the horizontal cross-sectional area of ​​the boss. The copper-aluminum diffusion layer retains a horizontal bonding area that is not squeezed by the boss during the forging process. The horizontal bonding area is adjacent to the side bonding area.

7. The manufacturing method of claim 6, wherein: It also includes milling the surface of the forged part in which the copper plate is embedded to remove the horizontal bonding area, thereby obtaining the multi-faceted composite copper-aluminum substrate.

8. The manufacturing method of claim 7, wherein: It also includes pressing the surface of the multi-faceted composite copper-aluminum substrate into an arc-shaped structure.

9. The manufacturing method of claim 5, wherein: The lower die of the forging die is provided with several forming holes. The upper die causes the copper material at the corresponding position of the boss to be embedded in the aluminum plate, while the material of the aluminum plate flows into the forming holes to form a heat sink. Then the upper end of the heat sink is cut flat to a uniform height.

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