Aluminum substrate copper layer bond strength enhancement method and system

Abstract

The present application relates to the technical field of aluminum substrate copper cladding, and particularly relates to a method and system for enhancing the bonding strength of an aluminum substrate copper cladding layer. The method comprises forming a microstructure layer through physical topography reconstruction, depositing a transition layer of intermetallic compound to obtain an interface transition structure, depositing copper material to form a copper cladding layer and control atomic diffusion to form a metallurgical bonding interface, applying thermal coupling to obtain a stress release structure, and generating a control instruction based on the deviation between the interface bonding strength parameter and the stress relief effect parameter for adaptive adjustment. The present application significantly improves the bonding strength of the copper cladding layer and relieves the interface thermal stress.

Description

Technical Field

[0001] This invention relates to the field of copper cladding technology on aluminum substrates, and more particularly to a method and system for enhancing the bonding strength of copper cladding layers on aluminum substrates. Background Technology

[0002] Aluminum-based copper-clad laminates are widely used in high-power devices such as power electronics and LED lighting due to their excellent heat dissipation and mechanical strength. In existing technologies, the mainstream methods for bonding aluminum substrates to copper layers include surface pretreatments such as physical roughening, chemical etching, and anodizing, followed by the formation of a copper coating on the surface through electroplating, electroless plating, or physical vapor deposition. The core of these conventional methods lies in improving the mechanical bonding effect of the copper layer by increasing the surface roughness of the aluminum substrate or forming a porous alumina layer.

[0003] Physical roughening typically involves sandblasting or mechanical grinding, creating a randomly distributed, uneven microstructure on the aluminum surface. Chemical etching utilizes acid or alkali solutions to corrode the aluminum substrate, producing a uniform pit structure. While these methods can provide a certain interfacial bonding area, the resulting microstructures are relatively uniform in scale and lack multi-level hierarchical structure. This results in numerous voids at the actual contact interface between the copper layer and the aluminum substrate, preventing the achievement of atomic-level dense bonding. During subsequent temperature cycling or power fluctuations, the stress caused by differences in thermal expansion coefficients can easily lead to the formation and gradual propagation of microcracks at the interface.

[0004] Another common practice is to pre-plate a metal interlayer, such as nickel or zinc, onto the aluminum substrate to mitigate the direct interfacial reaction between aluminum and copper. These interlayers are typically formed through displacement deposition or electroplating, and their composition and thickness are controlled by preset process parameters. However, under long-term use or high-temperature environments, the diffusion behavior between the interlayer and the aluminum substrate is often uncontrollable, easily forming brittle intermetallic compound phases, which reduces the bonding strength. Furthermore, these process parameters are often fixed after initial setting and cannot be dynamically adjusted based on actual interfacial bonding quality, leading to significant fluctuations in bonding performance between different batches of products.

[0005] Furthermore, traditional methods for handling interfacial stress mainly rely on optimizing the copper layer thickness or introducing a buffer layer, but these measures often come at the cost of sacrificing thermal conductivity or increasing process complexity. Finally, the stress relief effect of the bonded structure lacks an effective online evaluation and feedback mechanism. When the residual stress caused by the difference in thermal expansion coefficients of aluminum and copper accumulates to a critical value, failure problems such as interfacial delamination or bulging are difficult to avoid. Therefore, an improved solution that can enhance interfacial bonding strength and reliably cope with thermal stress is urgently needed. Summary of the Invention

[0006] The present invention provides a method and system for enhancing the bonding strength of copper-clad laminates on aluminum substrates, which can solve the problems in the prior art.

[0007] A first aspect of the present invention provides a method for enhancing the bonding strength of a copper-clad layer on an aluminum substrate, comprising: The surface of the aluminum substrate is subjected to physical morphology reconstruction treatment to form a microstructure layer with hierarchical scale characteristics on the surface of the aluminum substrate. An intermetallic compound transition layer is formed on the surface of the microstructure layer by deposition treatment to obtain an interface transition structure with gradient composition distribution. A copper-clad layer is formed by depositing copper material on the interface transition structure, and the atomic diffusion behavior between the interface transition structure and the copper-clad layer is controlled so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, resulting in a composite structure. A stress-relieving structure is obtained by applying a thermo-coupling effect to the composite structure. The stress-relieving structure is used to alleviate the interfacial stress caused by the difference in the thermal expansion coefficients between the aluminum substrate and the copper cladding layer. The interface bonding strength parameter of the composite structure is obtained, and an adjustment command is generated based on the deviation between the interface bonding strength parameter and the stress relief effect parameter of the stress release structure. The adjustment command is used to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-mechanical coupling effect.

[0008] The surface of an aluminum substrate undergoes physical morphology reconstruction to form a microstructure layer with hierarchical scale characteristics. An intermetallic compound transition layer is then deposited on the surface of this microstructure layer, resulting in an interface transition structure with a gradient composition distribution, including: Mechanical energy is applied to the surface of the aluminum substrate to obtain a first-scale morphological feature, which is used to provide a macroscopic anchoring effect. Chemical energy is applied to the surface of the first-scale morphological feature to obtain the second-scale morphological feature. The second-scale morphological feature is used to increase the interfacial contact area. The first-scale morphological feature and the second-scale morphological feature constitute the microstructure layer of the hierarchical morphological feature. A surface modification treatment is applied to the surface of the microstructure layer so that the surface energy state of the microstructure layer satisfies the interface wetting constraint condition, thereby obtaining a microstructure layer with regulated surface energy. Based on the surface tension state of the microstructure layer after surface energy regulation and the lattice parameters of the aluminum substrate and the copper layer to be coated, the compositional gradient sequence of the intermetallic compound material is determined. Intermetallic compound materials are sequentially deposited on the surface of the microstructure layer after surface energy modulation according to the composition gradient sequence to form the intermetallic compound transition layer. The lattice structure of the intermetallic compound transition layer changes continuously along the thickness direction to obtain the interface transition structure.

[0009] A surface modification treatment is applied to the surface of the microstructure layer to make the surface energy state of the microstructure layer satisfy the interface wetting constraint condition, thereby obtaining a surface energy-modulated microstructure layer, including: Elemental composition detection and chemical bond state analysis are performed on the surface of the microstructure layer to obtain elemental distribution information and chemical bond state information of the surface of the microstructure layer; Based on the elemental distribution information and the chemical bond state information, the surface tension value and surface active site density of the microstructure layer surface are calculated. The surface tension value is used to characterize the wettability of the microstructure layer surface, and the surface active site density is used to characterize the number of active sites on the microstructure layer surface available for chemical reactions. Based on the surface tension value and the surface active site density, and in conjunction with the target surface tension range and target active site density range indicated in the interface wetting constraint conditions, the modification intensity parameter and modification coverage range parameter of the surface modification treatment are determined. The surface of the microstructure layer is processed according to the modification intensity parameter and the modification coverage parameter, so that the surface tension value of the microstructure layer surface enters the target surface tension range and the surface active site density enters the target active site density range, thereby obtaining the microstructure layer after surface energy regulation.

[0010] A copper-clad layer is formed by depositing copper material on the interface transition structure, and the atomic diffusion behavior between the interface transition structure and the copper-clad layer is controlled, so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, resulting in a composite structure, including: Based on the thickness distribution and crystal structure information of the intermetallic compound transition layer, the copper material deposition temperature parameters and copper material deposition rate parameters are determined. Copper material is deposited on the surface of the interface transition structure according to the copper material deposition temperature parameters and the copper material deposition rate parameters to form the copper cladding layer; During the formation of the copper clad layer, the interfacial atomic concentration distribution between the interface transition structure and the copper clad layer is monitored to obtain diffusion flux information between the intermetallic compound transition layer and the copper clad layer. Based on the diffusion flux information, the copper material deposition temperature parameters are adjusted to allow atoms between the intermetallic compound transition layer and the copper cladding layer to diffuse into each other to meet the preset diffusion equilibrium conditions. While satisfying the preset diffusion equilibrium conditions, the copper plating deposition process is maintained, allowing atoms between the intermetallic compound transition layer and the copper plating layer to diffuse into each other to form atomic bonding regions. These atomic bonding regions constitute the metallurgical bonding interface, resulting in the composite structure.

[0011] Adjusting the copper material deposition temperature parameters based on the diffusion flux information to allow atomic interdiffusion between the intermetallic compound transition layer and the copper cladding layer to meet a preset diffusion equilibrium condition includes: Based on the diffusion flux information, calculate the first diffusion flux value of metal atoms in the intermetallic compound transition layer diffusing to the copper clad layer and the second diffusion flux value of copper atoms in the copper clad layer diffusing to the intermetallic compound transition layer; Calculate the diffusion flux ratio between the first diffusion flux value and the second diffusion flux value, and compare the diffusion flux ratio with a preset diffusion equilibrium ratio to calculate the deviation between the diffusion flux ratio and the preset diffusion equilibrium ratio; The temperature adjustment amount of the copper material deposition temperature parameter is determined based on the relationship between the deviation and the diffusion flux temperature response. The current copper material deposition temperature parameter is then processed based on the temperature adjustment amount to obtain the updated copper material deposition temperature parameter. The copper deposition process is controlled according to the updated copper material deposition temperature parameters, and the diffusion flux ratio is recalculated. When the deviation between the diffusion flux ratio and the preset diffusion equilibrium ratio meets the preset convergence threshold, it is confirmed that the inter-atomic diffusion satisfies the preset diffusion equilibrium condition.

[0012] Applying a thermo-coupling effect to the composite structure yields a stress-relieving structure, comprising: Stress field distribution is detected at the metallurgical bonding interface of the composite structure to obtain interface stress distribution information and stress concentration area information of the metallurgical bonding interface. Based on the interface stress distribution information and the stress concentration region information, the thermal field parameters and force field parameters are determined. The composite structure is processed according to the thermal field parameters to activate the atomic diffusion behavior at the metallurgical interface, so that the interface atoms between the aluminum substrate and the intermetallic compound transition layer and between the intermetallic compound transition layer and the copper cladding layer diffuse into each other. The atomic bonding density at the metallurgical interface is made to reach a preset target value by means of atomic diffusion behavior, and the composite structure is processed according to the force field parameters to trigger dislocation movement in the stress concentration region and obtain the stress relief structure.

[0013] Obtain the interfacial bonding strength parameter of the composite structure, generate a control command based on the deviation between the interfacial bonding strength parameter and the stress relief effect parameter of the stress-relieving structure, and use the control command to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-coupling effect, including: A peeling force is applied to the composite structure, and the critical peeling force value at which the copper-clad layer and the aluminum substrate separate at the interface is measured. The interface bonding strength parameter is calculated based on the critical peeling force value. A thermal cycling load is applied to the composite structure, and the change in residual stress at the metallurgical interface is measured. The stress relief effect parameter is calculated based on the change in residual stress. The strength deviation is determined based on the interface combined with the strength parameters and the preset strength target value, and the relief effect deviation is determined based on the stress relief effect parameters and the preset relief effect target value; Based on the intensity deviation, a first parameter adjustment amount is determined, and based on the mitigation effect deviation, a second parameter adjustment amount is determined, thereby generating the control command that includes the first parameter adjustment amount and the second parameter adjustment amount; The parameters in the physical morphology reconstruction process are adjusted according to the first parameter adjustment amount, and the parameters of the thermo-coupling effect are adjusted according to the second parameter adjustment amount.

[0014] A second aspect of the present invention provides a system for enhancing the bonding strength of copper-clad laminates on an aluminum substrate, comprising: The morphology reconstruction unit is used to perform physical morphology reconstruction processing on the surface of the aluminum substrate, forming a microstructure layer with hierarchical scale characteristics on the surface of the aluminum substrate, and performing a deposition process on the surface of the microstructure layer to form an intermetallic compound transition layer, thereby obtaining an interface transition structure with a gradient composition distribution. A copper-clad deposition unit is used to deposit copper material on the interface transition structure to form a copper-clad layer, and to control the atomic diffusion behavior between the interface transition structure and the copper-clad layer, so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, thereby obtaining a composite structure. A stress relief unit is used to apply a thermo-coupling effect to the composite structure to obtain a stress relief structure. The stress relief structure is used to alleviate the interface stress caused by the difference in the thermal expansion coefficients between the aluminum substrate and the copper cladding layer. An adaptive adjustment unit is used to obtain the interface bonding strength parameter of the composite structure, generate a control command based on the deviation between the interface bonding strength parameter and the stress relief effect parameter of the stress release structure, and use the control command to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-coupling effect.

[0015] A third aspect of the present invention provides an electronic device, comprising: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0016] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0017] This invention creates a multi-layered mechanically interlocking structure on the surface of an aluminum substrate through a hierarchical microstructure layer, significantly increasing the actual bonding area and providing a strong anchoring foundation for copper cladding adhesion. The intermetallic compound transition layer introduces a gradient composition distribution, eliminating abrupt changes in interface composition and achieving atomic-level bonding at the metallurgical interface. This greatly improves the peel strength of the copper cladding and maintains stable adhesion even under extreme conditions.

[0018] This invention precisely controls the synergistic effect of temperature and pressure through thermo-coupling, effectively releasing residual stress caused by the mismatch in thermal expansion coefficients between the aluminum substrate and the copper layer, and suppressing the initiation and propagation of interfacial microcracks. The composite structure, after stress release, exhibits significantly enhanced thermal cycling resistance, preventing delamination or blistering under high-temperature service conditions, thus fundamentally ensuring the long-term reliability of the copper-clad layer.

[0019] This invention utilizes an adaptive control mechanism that adjusts the deviation between interface bonding strength parameters and stress relief effect to optimize physical morphology reconstruction and thermo-coupling parameters in real time, ensuring that bonding strength and stress release effect are always in a synergistically optimal state. Closed-loop feedback eliminates the impact of process fluctuations, resulting in good consistency of bonding strength in batch production, significantly improved product qualification rate, and a wider process parameter window. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of a method for enhancing the bonding strength of copper-clad layers on aluminum substrates according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the process for determining the composite structure according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0023] Figure 1 This is a schematic flowchart of a method for enhancing the bonding strength of copper-clad laminates on an aluminum substrate according to an embodiment of the present invention. Figure 1 As shown, the method includes: The surface of the aluminum substrate is subjected to physical morphology reconstruction treatment to form a microstructure layer with hierarchical scale characteristics on the surface of the aluminum substrate. An intermetallic compound transition layer is formed on the surface of the microstructure layer by deposition treatment to obtain an interface transition structure with gradient composition distribution. A copper-clad layer is formed by depositing copper material on the interface transition structure, and the atomic diffusion behavior between the interface transition structure and the copper-clad layer is controlled so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, resulting in a composite structure. A stress-relieving structure is obtained by applying a thermo-coupling effect to the composite structure. The stress-relieving structure is used to alleviate the interfacial stress caused by the difference in the thermal expansion coefficients between the aluminum substrate and the copper cladding layer. The interface bonding strength parameter of the composite structure is obtained, and an adjustment command is generated based on the deviation between the interface bonding strength parameter and the stress relief effect parameter of the stress release structure. The adjustment command is used to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-mechanical coupling effect.

[0024] The surface of an aluminum substrate undergoes physical morphology reconstruction to form a microstructure layer with hierarchical scale characteristics. An intermetallic compound transition layer is then deposited on the surface of this microstructure layer, resulting in an interface transition structure with a gradient composition distribution, including: Mechanical energy is applied to the surface of the aluminum substrate to obtain a first-scale morphological feature, which is used to provide a macroscopic anchoring effect. Chemical energy is applied to the surface of the first-scale morphological feature to obtain the second-scale morphological feature. The second-scale morphological feature is used to increase the interfacial contact area. The first-scale morphological feature and the second-scale morphological feature constitute the microstructure layer of the hierarchical morphological feature. A surface modification treatment is applied to the surface of the microstructure layer so that the surface energy state of the microstructure layer satisfies the interface wetting constraint condition, thereby obtaining a microstructure layer with regulated surface energy. Based on the surface tension state of the microstructure layer after surface energy regulation and the lattice parameters of the aluminum substrate and the copper layer to be coated, the compositional gradient sequence of the intermetallic compound material is determined. Intermetallic compound materials are sequentially deposited on the surface of the microstructure layer after surface energy modulation according to the composition gradient sequence to form the intermetallic compound transition layer. The lattice structure of the intermetallic compound transition layer changes continuously along the thickness direction to obtain the interface transition structure.

[0025] Applying mechanical energy to the surface of the aluminum substrate can be achieved through sandblasting or laser etching. Taking sandblasting as an example, corundum abrasive particles with a diameter ranging from 100μm to 300μm are uniformly blasted onto the aluminum substrate surface at a pressure of 0.3MPa to 0.6MPa. This creates a macroscopic rough morphology on the substrate surface, characterized by alternating grooves and protrusions with a depth of 10μm to 50μm and a spacing of 80μm to 200μm—the first-scale morphological feature. This first-scale morphological feature provides a mechanical anchoring effect for the subsequent copper-clad layer, enabling it to resist interface separation through geometric interlocking when subjected to shear or peeling forces. After sandblasting, the aluminum substrate surface must be ultrasonically cleaned to remove residual abrasive particles and surface contaminants, ensuring the uniformity of subsequent chemical processing.

[0026] Chemical energy is applied to the surface of the first-scale morphological features to obtain second-scale morphological features. Specifically, a phosphoric acid-oxalic acid mixed solution is used to micro-etch the aluminum substrate. The volume fraction of phosphoric acid is controlled between 15% and 25%, and the mass fraction of oxalic acid is controlled between 3% and 8%. The processing temperature is maintained between 40°C and 60°C, and the processing time is between 5 min and 15 min. During the chemical etching process, the mixed acid preferentially erodes along the grain boundaries and dislocations on the surface of the aluminum substrate, forming micro- and nano-scale pits and mesh trenches with depths between 0.5 μm and 5 μm and a distribution density on the order of thousands per square millimeter on the trench walls and protrusion tops of the first-scale morphological features, constituting the second-scale morphological features. The first-scale and second-scale morphological features together constitute a hierarchical microstructure layer. The superposition of the two-level structure increases the actual contact area on the surface of the aluminum substrate by 3 to 8 times compared to a flat surface, providing sufficient effective bonding area for the subsequent deposition of intermetallic compound transition layers.

[0027] Surface modification treatment was applied to the surface of the microstructure layer to regulate its surface energy state and meet the interfacial wetting constraint conditions. Specifically, plasma bombardment was employed, using a mixture of argon and oxygen as the working gas. The argon-to-oxygen flow ratio was controlled between 3:1 and 5:1, and the radio frequency power was set between 100W and 300W. The treatment time was 3 to 10 minutes. During the plasma treatment, high-energy particles bombarded the aluminum substrate surface, removing residual natural oxide film and organic contaminants from the microstructure layer surface. Simultaneously, a large number of active dangling bonds and oxygen-containing functional groups were introduced into the aluminum substrate surface, reducing the surface energy from approximately 30 mJ / m² before treatment.2 Increased to 30mJ / m 2 The above. The increase in surface energy significantly reduces the wetting angle of the subsequently deposited intermetallic compound material on the aluminum substrate surface, thereby ensuring that the intermetallic compound material can fully spread and fill the fine pores of the microstructure layer, resulting in a microstructure layer with surface energy regulated.

[0028] Based on the surface tension state of the microstructure layer after surface energy modulation and the lattice parameters of the aluminum substrate and the copper layer to be coated, the compositional gradient sequence of the intermetallic compound material was determined. The lattice constant of the aluminum substrate is approximately 0.4049 nm, and the lattice constant of copper is approximately 0.3615 nm, with a lattice mismatch of approximately 10.7%. If copper is deposited directly on the aluminum substrate, the large lattice mismatch will lead to high-density dislocations and residual stress at the interface. Therefore, an intermetallic compound transition layer with continuously changing composition needs to be introduced between aluminum and copper to achieve a gradient transition of lattice parameters. According to the phase diagram of the Al-Cu binary system, selectable intermetallic compound phases include Al₂Cu, AlCu, Al₂Cu₃, etc., whose lattice parameters gradually transition from the aluminum side to the copper side. The principle for determining the compositional gradient sequence is: the lattice mismatch between two adjacent intermetallic compound layers should not exceed 5% to control the dislocation density at the interface within an acceptable range, while ensuring that the overall lattice structure of the transition layer changes continuously along the thickness direction rather than abruptly.

[0029] On the surface of the microstructured layer after surface energy modulation, intermetallic compound materials are sequentially deposited according to a defined compositional gradient sequence to form an intermetallic compound transition layer. The deposition method employs magnetron sputtering technology, using high-purity aluminum and copper targets as sputtering sources. The aluminum-copper atomic ratio of the deposited layer is controlled by adjusting the sputtering power ratio of the aluminum and copper targets. Near the aluminum substrate, the aluminum target power is set higher while the copper target power is set lower, resulting in an aluminum-rich intermetallic compound, corresponding to the Al₂Cu phase. As the deposition thickness increases, the aluminum target power is gradually decreased while the copper target power is increased, sequentially passing through the AlCu and Al₂Cu₃ phases, until reaching the AlCu₃ phase near the copper-clad layer. The deposition thickness of each intermetallic compound layer is controlled between 50 nm and 200 nm, and the total thickness of the entire transition layer is controlled between 0.5 μm and 2 μm. During deposition, the substrate temperature is maintained between 150 °C and 250 °C to promote short-range atomic diffusion at the interface and enhance the metallurgical bonding between layers. The base vacuum level within the deposition chamber is better than 5 × 10⁻⁶. -4 The working pressure is maintained between 0.3 Pa and 0.8 Pa to ensure that the mean free path of the sputtered particles meets the requirements for uniform deposition.

[0030] After the intermetallic compound transition layer is deposited, its lattice structure continuously varies along the thickness direction. The aluminum-copper atomic ratio gradually transitions from 2:1 near the aluminum substrate side to 1:3 near the copper cladding layer side, and the corresponding lattice constant also gradually transitions from a larger value on the aluminum side to a smaller value on the copper side. This gradient composition distribution creates a continuous bridging of lattice parameters between the aluminum substrate and the subsequent copper cladding layer, effectively eliminating high-density interface defects caused by lattice mismatch when aluminum and copper are in direct contact. Simultaneously, the gradient composition distribution also causes the coefficient of thermal expansion of the interface transition structure to vary gradually along the thickness direction; the coefficient of thermal expansion of aluminum is approximately 23.1 × 10⁻⁶. -6 At ℃, the coefficient of thermal expansion of copper is approximately 16.5 × 10⁻⁶. -6 The presence of the transition layer at a temperature of / ℃ disperses the difference in thermal expansion coefficients across multiple sub-layer interfaces, preventing thermal stress concentration at a single interface and thus providing a structural foundation for the reliability of the subsequent composite structure. The resulting interface transition structure combines the mechanical anchoring effect brought by the hierarchical morphology, the metallurgical bonding capability provided by the intermetallic compound transition layer, and the thermal stress relief function achieved by the gradient composition distribution, laying the foundation for a high-strength and reliable bond between the aluminum substrate and the copper clad layer.

[0031] A surface modification treatment is applied to the surface of the microstructure layer to make the surface energy state of the microstructure layer satisfy the interface wetting constraint condition, thereby obtaining a surface energy-modulated microstructure layer, including: Elemental composition detection and chemical bond state analysis are performed on the surface of the microstructure layer to obtain elemental distribution information and chemical bond state information of the surface of the microstructure layer; Based on the elemental distribution information and the chemical bond state information, the surface tension value and surface active site density of the microstructure layer surface are calculated. The surface tension value is used to characterize the wettability of the microstructure layer surface, and the surface active site density is used to characterize the number of active sites on the microstructure layer surface available for chemical reactions. Based on the surface tension value and the surface active site density, and in conjunction with the target surface tension range and target active site density range indicated in the interface wetting constraint conditions, the modification intensity parameter and modification coverage range parameter of the surface modification treatment are determined. The surface of the microstructure layer is processed according to the modification intensity parameter and the modification coverage parameter, so that the surface tension value of the microstructure layer surface enters the target surface tension range and the surface active site density enters the target active site density range, thereby obtaining the microstructure layer after surface energy regulation.

[0032] After reconstructing the physical morphology of the aluminum substrate surface and forming a microstructure layer with hierarchical scale characteristics, further surface modification treatment is required to ensure that the surface energy state meets the interfacial wetting constraint conditions, thereby creating a favorable interfacial chemical environment for the subsequent deposition of the intermetallic compound transition layer. The core of this process lies in accurately characterizing the chemical state of the microstructure layer surface and formulating targeted modification strategies accordingly.

[0033] When determining the elemental composition of the microstructured surface layer, X-ray photoelectron spectroscopy (XPS) was used to perform a full-spectrum scan of the elements and their chemical valence states within a depth range of 0 to 10 nanometers, obtaining the atomic percentage distribution of aluminum, oxygen, carbon, and any impurities. Simultaneously, Auger electron spectroscopy (AES) combined with ion sputtering depth profiling was used to obtain the elemental distribution gradient information along the depth direction, forming complete elemental distribution information. Chemical bond state analysis relied on the high-resolution narrow-scan XPS spectrum to fit and separate the core energy level peaks such as Al 2p and O 1s, identifying the relative proportions of different chemical bond states such as Al-O, Al-OH, and Al-Al bonds, thus forming chemical bond state information. These two types of information together form the input basis for subsequent surface energy calculations, ensuring an accurate description of the true chemical state of the microstructured surface layer.

[0034] Based on the acquired elemental distribution and chemical bond state information, the surface tension and surface active site density of the microstructure layer were calculated. The surface tension was calculated using a combination of the contact angle method and surface energy component theory: three standard liquids—deionized water, formamide, and diiodomethane—were selected, and the static contact angles were measured on the surface of the microstructure layer. The Owens-Wendt-Rabel-Kaelble (OWRK) model was used to decompose the surface tension into polar components. With dispersion component Total surface tension satisfy ,in The unit is mN / m. Surface tension is used to characterize the wetting ability of the microstructured layer surface for subsequent deposited materials. A higher value indicates more thorough interfacial wetting, which is beneficial for forming a tight physical contact between the intermetallic compound transition layer and the microstructured layer. Surface active site density. The calculation is based on the areal density estimation of Al-OH bonds in the chemical bond state information, combined with the number of hydroxyl groups that can participate in chemical adsorption or chemical reaction per unit area, and is quantitatively expressed in terms of the number of active sites per square nanometer. The number of active sites available for chemical reactions on the surface of the microstructure layer used to characterize the structure directly affects the probability and density of subsequent interfacial chemical bonding.

[0035] Obtaining surface tension values With surface active site density Then, the two are compared with the target surface tension range preset in the interface wetting constraint conditions. and the density range of target active sites A comparison is performed to determine the degree of deviation between the current surface state and the target state. If... This indicates insufficient surface tension and low wetting ability, requiring enhancement modification to increase the number of surface polar groups; if This indicates that the surface tension is too high, which will cause the deposited material to spread excessively, and the modification strength needs to be appropriately reduced. Similarly, if Then the amount of active site introduced needs to be increased; if Therefore, it is necessary to control the modification coverage area to avoid interfacial chemical inhomogeneity caused by excessively dense active sites. Based on the above deviation analysis, the modification intensity parameters of the surface modification treatment are determined. With modified coverage parameters Modified strength parameters Characterized by the modified energy density or chemical reagent concentration applied per unit area, and the modification coverage parameter. The spatial coverage ratio of the modification treatment on the surface of the microstructure layer is characterized, and the two together determine the implementation scheme of the modification treatment.

[0036] Based on the modified strength parameters With modified coverage parameters Specific modification treatments are applied to the surface of the microstructure layer. The modification method can be selected from one or a combination of plasma activation treatment, ultraviolet ozone treatment, or chemical solution impregnation treatment, depending on the actual deviation. Taking plasma activation treatment as an example, the modification intensity parameters are controlled by adjusting the radio frequency power, gas flow rate (usually a mixture of argon and oxygen), and treatment time. Precise control; the modification coverage parameters are achieved by adjusting the scanning path and scanning interval of the plasma spray gun. Precise control is achieved. During plasma treatment, high-energy particles bombard the surface of the microstructure layer, breaking the chemical bonds of surface organic contaminants and removing them. Simultaneously, a large number of active functional groups such as hydroxyl (Al-OH) and peroxyl (Al-OO·) groups are introduced onto the aluminum oxide layer surface, thereby simultaneously increasing the surface tension and the density of surface active sites. Regarding the modification coverage parameters... In smaller cases, a mask-assisted local modification method can be used. Photoresist or physical shielding plates are used to protect the unmodified areas, ensuring that the modification treatment only acts on the designated area, thereby achieving spatial selective control of the chemical state of the microstructure layer surface.

[0037] After modification, contact angle measurements and XPS analysis were performed again on the surface of the microstructure layer to verify the surface tension value. Has the target surface tension range been reached? and surface active site density Has it entered the target active site density range? If both indicators meet the constraints, the surface modification treatment is considered complete, resulting in a microstructure layer with regulated surface energy, which can then proceed to the subsequent deposition process of the intermetallic compound transition layer. If either indicator still exceeds the target range, the modification intensity parameter is recalculated based on the current deviation. With modified coverage parameters Furthermore, supplementary modification treatments were applied to the surface of the microstructure layer until both indicators met the interfacial wetting constraint conditions. This closed-loop verification mechanism ensured the reliability and consistency of the surface modification results, providing a stable surface chemical basis for the subsequent formation of the metallurgical bonding interface.

[0038] The microstructure layer after surface energy modulation retains the hierarchical microstructure in terms of physical morphology and has sufficient surface tension and active site density in terms of chemical state. The synergistic effect of the two enables the subsequently deposited intermetallic compound transition layer to form chemical bonds with the microstructure layer while wetting and spreading, significantly improving the interfacial bonding strength and laying a key interfacial chemical foundation for enhancing the overall copper cladding layer bonding strength of the aluminum substrate.

[0039] Figure 2 This is a schematic diagram illustrating the process of determining the composite structure according to an embodiment of the present invention. Figure 2 As shown, a copper-clad layer is formed by depositing copper material on the interface transition structure, and the atomic diffusion behavior between the interface transition structure and the copper-clad layer is controlled, so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, resulting in a composite structure, including: Based on the thickness distribution and crystal structure information of the intermetallic compound transition layer, the copper material deposition temperature parameters and copper material deposition rate parameters are determined. Copper material is deposited on the surface of the interface transition structure according to the copper material deposition temperature parameters and the copper material deposition rate parameters to form the copper cladding layer; During the formation of the copper clad layer, the interfacial atomic concentration distribution between the interface transition structure and the copper clad layer is monitored to obtain diffusion flux information between the intermetallic compound transition layer and the copper clad layer. Based on the diffusion flux information, the copper material deposition temperature parameters are adjusted to allow atoms between the intermetallic compound transition layer and the copper cladding layer to diffuse into each other to meet the preset diffusion equilibrium conditions. While satisfying the preset diffusion equilibrium conditions, the copper plating deposition process is maintained, allowing atoms between the intermetallic compound transition layer and the copper plating layer to diffuse into each other to form atomic bonding regions. These atomic bonding regions constitute the metallurgical bonding interface, resulting in the composite structure.

[0040] The thickness distribution and crystal structure information of the intermetallic compound transition layer are crucial for determining subsequent copper deposition process parameters. Through transmission electron microscopy (TEM) cross-sectional analysis and X-ray diffraction (XRD) phase identification, the thickness distribution pattern of the intermetallic compound transition layer along the interface normal can be obtained, and the main phases present can be identified, such as intermetallic compound phases with different stoichiometric ratios, like CuAl2, CuAl, or Cu9Al4. Different phases have different lattice parameters and thermodynamic stability, significantly affecting the atomic diffusion behavior during copper deposition. Regarding thickness distribution information, if the transition layer thickness uniformity is high, the deposition parameter window is relatively wide; if there are local abrupt thickness changes, the deposition temperature tolerance range needs to be narrowed accordingly to avoid local over-diffusion leading to brittle phase enrichment. Based on these two types of information, the diffusion barrier height and interface activation energy of the transition layer are comprehensively evaluated to determine the initial settings for the copper deposition temperature and deposition rate parameters.

[0041] The logic behind determining the copper deposition temperature parameter lies in the fact that deposition temperature directly affects the migration rate of copper atoms at the interface. Too low a temperature prevents copper atoms from fully penetrating into the transition layer, resulting in mechanical intercalation rather than metallurgical bonding. Too high a temperature causes excessive outward diffusion of aluminum atoms from the transition layer to the copper layer, forming a continuous brittle intermetallic compound layer, which reduces interface toughness. The logic behind determining the copper deposition rate parameter lies in the fact that the deposition rate determines the flux density of copper atoms reaching the interface per unit time. Too high a rate leads to copper atom accumulation at the interface, inhibiting the establishment of a bidirectional diffusion equilibrium. Too slow a rate results in prolonged exposure of the interface to a high-temperature environment, increasing the risk of oxidation. Therefore, co-optimizing the deposition temperature and deposition rate parameters as coupled variables is the core strategy for achieving quality control of the metallurgical bonding interface.

[0042] Following the determined copper deposition temperature and rate parameters, copper deposition is performed on the interface transition structure surface. Deposition methods can include physical or chemical methods such as magnetron sputtering, electron beam evaporation, or chemical vapor deposition. The specific process path chosen depends on the target thickness and uniformity requirements of the copper layer. In magnetron sputtering, the target power density and substrate bias voltage jointly determine the incident energy and deposition rate of copper atoms. Accurate calculation and setting of the power density are necessary based on the determined deposition rate parameters. The substrate temperature is maintained within the set deposition temperature range using a heating stage or radiant heating, and is monitored in real-time using thermocouples or infrared thermometers to ensure that the temperature deviation throughout the deposition process is controlled within ±5℃.

[0043] During the formation of the copper-clad layer, the atomic concentration distribution at the interface between the transition structure and the copper-clad layer is monitored in real time. Monitoring methods can include in-situ Auger electron spectroscopy (AES) depth profiling or secondary ion mass spectrometry (SIMS). Through intermittent or continuous sampling, the concentration gradient curves of copper, aluminum, and transition layer constituent elements (such as zinc, nickel, and other intermediate layer elements) along the interface normal are obtained. Based on the concentration gradient distribution data, the diffusion flux information between the intermetallic compound transition layer and the copper-clad layer is calculated. Diffusion flux reflects the mass of atoms traversing a unit area of ​​the interface per unit time and is a core quantitative indicator for determining whether the interfacial diffusion behavior is in a dynamic equilibrium state. When the ratio of the diffusion flux from copper to the transition layer to the diffusion flux from aluminum to the copper-clad layer deviates from the preset equilibrium range, an adjustment response of the deposition temperature parameters is triggered.

[0044] The specific logic for dynamically adjusting the copper deposition temperature parameters based on diffusion flux information is as follows: If the diffusion flux of copper towards the transition layer is low, it indicates that the current temperature is insufficient to activate sufficient copper atom diffusion. The deposition temperature should be appropriately increased to enhance the thermal activation and migration ability of copper atoms. If the diffusion flux of aluminum towards the copper coating layer is too high, it indicates that the outward diffusion of aluminum is too active, posing a risk of forming a continuous brittle phase. The deposition temperature should be appropriately reduced, and the deposition rate can be increased to shorten the exposure time of the interface at high temperatures. The adjustment range is proportional to the magnitude of the diffusion flux deviation. After each adjustment, a certain thermal equilibrium establishment time (usually 30 seconds to 2 minutes, depending on the heat capacity of the process chamber) is required before re-collecting interface concentration distribution data to evaluate the adjustment effect, forming a closed-loop feedback control process.

[0045] The definition of the preset diffusion equilibrium condition is a key technical element of this step. The preset diffusion equilibrium condition typically includes constraints in the following dimensions: the ratio of copper-aluminum interdiffusion flux falls within a target range (e.g., the ratio of copper-to-aluminum diffusion flux to aluminum-to-copper diffusion flux is between 0.8 and 1.2); the interface concentration gradient curve exhibits a continuous and smooth transition without any abrupt concentration steps; and the growth rate of the intermetallic compound transition layer thickness during deposition is lower than a set threshold, indicating that the transition layer thickness tends to stabilize. All three conditions must be met simultaneously to determine that the diffusion equilibrium condition has been achieved. After the preset diffusion equilibrium condition is met, the copper plating deposition process continues, allowing the atomic interdiffusion between the intermetallic compound transition layer and the copper plating layer to stably persist in a dynamic equilibrium state.

[0046] During the deposition stage, which continuously satisfies the preset diffusion equilibrium conditions, copper and aluminum atoms undergo sufficient mutual substitution and embedding in the interface region, gradually forming atomically bonded regions at the interface between the intermetallic compound transition layer and the copper plating layer. The essence of these atomically bonded regions is a mixed network of covalent and metallic bonds formed by copper and aluminum atoms at the crystal lattice level, with binding energies significantly higher than those of purely mechanical intercalation or physical adsorption interfaces. The width of these atomically bonded regions typically ranges from several nanometers to tens of nanometers, and their width and uniformity directly determine the mechanical properties of the metallurgical interface. The atomically bonded regions constitute the metallurgical interface, elevating the bonding between the aluminum substrate and the copper plating layer from a physical contact level to an atomic-scale metallurgical bonding level. This fundamentally enhances the interfacial bonding strength and anti-peeling ability, ultimately resulting in a composite structure with a high-quality metallurgical interface. In this composite structure, the aluminum substrate, intermetallic compound transition layer, atomically bonded regions, and copper plating layer form a continuous gradient structure from the aluminum side to the copper side, effectively avoiding abrupt changes in mechanical properties at the interface and providing a structural basis for subsequent thermo-coupling stress relief treatment.

[0047] Adjusting the copper material deposition temperature parameters based on the diffusion flux information to allow atomic interdiffusion between the intermetallic compound transition layer and the copper cladding layer to meet a preset diffusion equilibrium condition includes: Based on the diffusion flux information, calculate the first diffusion flux value of metal atoms in the intermetallic compound transition layer diffusing to the copper clad layer and the second diffusion flux value of copper atoms in the copper clad layer diffusing to the intermetallic compound transition layer; Calculate the diffusion flux ratio between the first diffusion flux value and the second diffusion flux value, and compare the diffusion flux ratio with a preset diffusion equilibrium ratio to calculate the deviation between the diffusion flux ratio and the preset diffusion equilibrium ratio; The temperature adjustment amount of the copper material deposition temperature parameter is determined based on the relationship between the deviation and the diffusion flux temperature response. The current copper material deposition temperature parameter is then processed based on the temperature adjustment amount to obtain the updated copper material deposition temperature parameter. The copper deposition process is controlled according to the updated copper material deposition temperature parameters, and the diffusion flux ratio is recalculated. When the deviation between the diffusion flux ratio and the preset diffusion equilibrium ratio meets the preset convergence threshold, it is confirmed that the inter-atomic diffusion satisfies the preset diffusion equilibrium condition.

[0048] After completing the deposition of the intermetallic compound transition layer and obtaining diffusion flux information, it is necessary to finely control the deposition temperature parameters of the copper material to ensure that the inter-atomic diffusion between the intermetallic compound transition layer and the copper cladding layer reaches the preset diffusion equilibrium condition. The diffusion flux information comes from the real-time monitoring of atomic migration behavior in the interface region, including obtaining the concentration gradient distribution of each element at the interface using in-situ transmission electron microscopy, Rutherford backscatter spectroscopy, or secondary ion mass spectrometry, thereby providing reliable input data for subsequent calculations.

[0049] Based on the acquired diffusion flux information, the diffusion flux values ​​in both directions are calculated. The diffusion flux formed by the migration of metal atoms (including aluminum atoms and other alloying element atoms in the aluminum-copper intermetallic compound phase) from the intermetallic compound transition layer towards the copper cladding layer is defined as the first diffusion flux value. The unit is mol / (m 2 The diffusion flux formed by the migration of copper atoms in the copper-clad layer towards the intermetallic compound transition layer is defined as the second diffusion flux value. The units are both mol / (m 2 Both are calculated based on Fick's first law, combined with the concentration gradient and diffusion coefficient on both sides of the interface. Specifically, It depends on the metal atom concentration gradient on the intermetallic compound transition layer side and the diffusion coefficient at the corresponding temperature. This depends on the concentration gradient of copper atoms on the copper-clad layer side and its diffusion coefficient. In actual calculations, the diffusion coefficient itself is a function of temperature, following the Arrhenius relation; therefore, changes in deposition temperature directly affect... and The value.

[0050] In obtaining and Next, the diffusion flux ratio between the two is calculated. ,Right now .Will Ratio to preset diffusion equilibrium value Compare and calculate the deviation. Preset diffusion equilibrium ratio The rationale behind this design is that when the interdiffusion of atoms on both sides of the interface is in relative equilibrium, the intermetallic compound transition layer will not become embrittled due to excessive unidirectional consumption, nor will it form an uneven copper-rich phase due to a large influx of copper atoms, thus ensuring that the metallurgical interface has good mechanical properties and thermal stability. Under normal circumstances... The value ranges from 0.8 to 1.2, and the specific value is calibrated according to the aluminum substrate alloy composition and copper cladding thickness requirements. Deviation This reflects the degree to which the interfacial diffusion behavior deviates from the ideal equilibrium state under the current depositional conditions, and is the core basis for subsequent temperature adjustments.

[0051] According to the deviation The temperature adjustment amount for copper deposition temperature parameters is determined by the relationship between diffusion flux and temperature response. The diffusion flux-temperature response describes the change in the diffusion flux ratio caused by a unit change in deposition temperature within the current process window, and can be expressed as follows: The derivative value is obtained through a pre-established process database or a finite element thermal-diffusion coupling simulation model. The calculation of the temperature adjustment amount satisfies... That is, by using a negative feedback mechanism to shift the diffusion flux ratio to Direction correction. When This indicates that the diffusion of metal atoms on the transition layer side of the intermetallic compound is too active, and the deposition temperature needs to be appropriately reduced to suppress it. growth; when In such cases, the deposition temperature needs to be appropriately increased to promote the uniformity of atomic interdiffusion. In practice, to prevent excessive temperature adjustments from causing process instability, [further measures should be taken]. Set an upper limit constraint, and the adjustment range in a single instance shall not exceed the preset maximum step size value, which is usually no more than 5% of the current deposition temperature.

[0052] Based on the calculation Regarding the current copper material deposition temperature parameters The parameters for copper material deposition temperature were updated to obtain the updated parameters. .Will The input is sent to the copper clad layer deposition control unit to adjust the heating power of the equipment used in processes such as magnetron sputtering, electron beam evaporation, or electrochemical deposition, or the substrate temperature control module, so that the actual deposition temperature is stabilized at [temperature value missing]. Nearby. After the temperature stabilizes, recollect the interface diffusion flux information and recalculate. , and the updated diffusion flux ratio And recalculate the deviation. .

[0053] Determine the updated deviation Does it meet the preset convergence threshold? ,Right now Preset convergence threshold The setting takes into account both process measurement accuracy and interface bonding performance requirements, and is typically between 0.05 and 0.1. If... If this is confirmed, the current atomic interdiffusion state meets the preset diffusion equilibrium condition, and the deposition temperature parameter is locked at [value missing]. The subsequent copper plating deposition process continues at this temperature. Then Using this as a new baseline, the above deviation calculation and temperature adjustment process is repeated until the convergence condition is met. The entire control process constitutes a closed-loop iterative optimization mechanism, and convergence is usually achieved within 3 to 8 iterations, ensuring that the interface diffusion behavior remains stable in the preset equilibrium state.

[0054] At the engineering implementation level, the aforementioned temperature control process is integrated with the real-time feedback control system of the copper plating deposition equipment. The acquisition cycle of diffusion flux information is matched with the timescale of the deposition process. For magnetron sputtering, the acquisition cycle is typically set to 30 to 120 seconds; for electrochemical deposition, it can be appropriately extended to several minutes depending on the current density and coating growth rate. Temperature adjustment commands are transmitted to the equipment controller via a digital interface, with a response time within seconds, ensuring real-time control. Through the aforementioned adaptive temperature control strategy, the atomic interdiffusion behavior between the intermetallic compound transition layer and the copper plating layer is precisely controlled, avoiding defects such as Kirkendal voids and brittle phase enrichment at the interface caused by diffusion imbalance. This results in a uniformly composed and highly bonded metallurgical interface between the aluminum substrate and the copper plating layer, laying a stable interface foundation for subsequent thermal coupling processing.

[0055] Applying a thermo-coupling effect to the composite structure yields a stress-relieving structure, comprising: Stress field distribution is detected at the metallurgical bonding interface of the composite structure to obtain interface stress distribution information and stress concentration area information of the metallurgical bonding interface. Based on the interface stress distribution information and the stress concentration region information, the thermal field parameters and force field parameters are determined. The composite structure is processed according to the thermal field parameters to activate the atomic diffusion behavior at the metallurgical interface, so that the interface atoms between the aluminum substrate and the intermetallic compound transition layer and between the intermetallic compound transition layer and the copper cladding layer diffuse into each other. The atomic bonding density at the metallurgical interface is made to reach a preset target value by means of atomic diffusion behavior, and the composite structure is processed according to the force field parameters to trigger dislocation movement in the stress concentration region and obtain the stress relief structure.

[0056] In the process of applying thermo-coupling to a composite structure to obtain a stress-relieving structure, the primary task is to accurately grasp the stress state at the metallurgical interface. A comprehensive stress field distribution detection at the metallurgical interface in the composite structure is performed by combining high-resolution X-ray diffraction stress analysis with synchrotron radiation diffraction. During the detection, a two-dimensional scan is conducted along the interface plane, with sampling intervals set within the range of 5μm to 20μm to ensure sufficient spatial resolution of stress distribution data. Simultaneously, strain field mapping of the interface region is performed using digital image correlation technology, cross-referencing the measurement results with finite element simulation results to ultimately obtain complete interface stress distribution information. Based on this, statistical analysis methods are used to identify regions where the stress amplitude exceeds 150% of the local average stress value. These regions are designated as stress concentration areas, and their spatial coordinates, area range, and stress concentration degree are recorded to form stress concentration area information.

[0057] Based on the acquired interfacial stress distribution and stress concentration region information, the thermal and force field parameters are systematically determined. The determination of the thermal field parameters requires comprehensive consideration of the difference in thermal expansion coefficients between the aluminum substrate and the copper cladding layer, the thermal stability of the intermetallic compound transition layer, and the target atom diffusion activation energy. The thermal expansion coefficient of aluminum is approximately 23 × 10⁻⁶. -6 / K, the coefficient of thermal expansion of copper is approximately 17 × 10⁻⁶. -6 / K, approximately 6×10 between the two -6 The difference in K / 2 is the fundamental cause of interfacial stress. The thermal field application temperature parameter is typically set within the temperature range where the aluminum-copper intermetallic compound phase is stable, i.e., between 200℃ and 350℃. The specific value is determined by linear mapping from the maximum principal stress amplitude in the interfacial stress distribution information. The thermal field application time parameter is estimated based on the relationship between the target atom diffusion depth and the diffusion coefficient, ensuring sufficient interfacial diffusion of interfacial atoms at the set temperature. The determination of the force field application parameters focuses on the stress concentration factor and the critical shear stress for dislocation motion in the stress concentration region. By superimposing the additional stress generated by the applied force field onto the local stress field of the stress concentration region, the equivalent shear stress in that region exceeds the critical value for dislocation motion, thereby triggering effective dislocation slip and climb behavior.

[0058] The composite structure was heat-treated according to the determined thermal field parameters to activate atomic diffusion at the metallurgical interface. A segmented heating strategy was employed, raising the composite structure from room temperature to the target thermal field temperature at a rate of 30°C / min to 50°C / min. This prevented excessively rapid heating from causing new interface damage due to thermal expansion differences between the aluminum substrate and the copper clad layer. During the target temperature holding phase, aluminum atoms at the interface between the aluminum substrate and the intermetallic compound transition layer gained sufficient thermal activation energy to overcome the interface barrier and migrate into the intermetallic compound transition layer. Simultaneously, metal atoms in the intermetallic compound transition layer also diffused back towards the aluminum substrate, forming a diffusion transition region with a gradual change in composition between the aluminum substrate and the intermetallic compound transition layer. Similarly, at the interface between the intermetallic compound transition layer and the copper clad layer, copper atoms interdiffused with metal atoms in the transition layer, further strengthening the metallurgical bonding at both interfaces. This synchronous atomic interdiffusion behavior at both interfaces transformed the compositional distribution of the interface region from an abrupt change to a gradual change, effectively reducing the chemical potential inhomogeneity caused by the compositional gradient at the interface.

[0059] During heat treatment, the atomic bond density at the metallurgical interface is tracked in real time using online monitoring. The atomic bond density is characterized using a non-destructive testing method based on the acoustic wave propagation characteristics of the interface. The trend of change in the atomic bond density is indirectly assessed by measuring the transmission and reflection coefficients of ultrasonic waves at the interface. When the atomic bond density reaches the preset target value, the thermal field treatment phase ends, and the force field treatment phase begins. The preset target value is set based on the premise that the interface bonding strength at this level can meet the requirements of thermal cycling loads under subsequent service conditions. It is typically determined using a pre-established calibration curve between bond density and interface bonding strength. If the atomic bond density still does not reach the target value within the specified maximum holding time, a parameter adjustment mechanism is triggered, appropriately increasing the thermal field treatment temperature or extending the holding time, and a re-evaluation is performed.

[0060] The force field application stage is implemented after heat treatment and cooling of the composite structure to an appropriate temperature, or simultaneously applied via thermo-mechanical coupling while the thermal field is being applied. The specific choice is determined based on the distribution characteristics of the stress concentration region and the temperature sensitivity of dislocation motion. The application method of the force field adopts a differentiated strategy according to the spatial distribution of the stress concentration region: for stress concentration regions distributed in the middle of the interface, a uniform surface pressure loading method is used, applying uniform compressive stress perpendicular to the interface plane to the composite structure through hydraulic equipment; for stress concentration regions distributed at the edges or corners of the interface, a local point pressure or rolling method is used, applying concentrated loads at the corresponding positions using a high-precision servo pressure system. The load amplitude setting in the force field application parameters must ensure that the equivalent shear stress in the stress concentration region exceeds the critical shear stress of the material at that temperature, thereby activating the dislocation slip system and causing dislocations to undergo directional motion in the crystal lattice. The extensive movement and rearrangement of dislocations, on the one hand, directly reduce the local stress level in the stress concentration area through the release of strain energy, and on the other hand, form stable low-energy configurations such as subgrain boundaries through the interaction of dislocations, transforming the original high-energy stress concentration state into a low-energy uniform stress distribution state, ultimately resulting in a stress-relieving structure with uniform distribution of interfacial stress.

[0061] After the force field application ends, the stress field of the stress-relieving structure is re-measured to verify whether the stress concentration in the stress concentration area has been reduced to the target range. If the re-measurement results show that the stress concentration coefficient still exceeds the allowable value, the force field parameters are adjusted according to the deviation, the load amplitude is increased or the loading position is adjusted, and the force field is reapplied until the stress concentration meets the requirements. Throughout the thermo-mechanical coupling process, the synergistic cooperation of the temperature field and the force field is key to achieving effective stress release: the thermal field reduces the yield strength of the material, decreasing the lattice resistance that dislocation movement needs to overcome, allowing the force field to achieve sufficient dislocation movement with a smaller external load; the force field, by introducing directional plastic deformation, accelerates the stress homogenization process in the interface region and promotes the opening of atomic diffusion channels at the interface, further enhancing the atomic diffusion effect during the thermal field application stage. Both promote each other, jointly achieving the effective elimination of stress concentration at the metallurgical interface and the overall improvement of the interface bonding quality.

[0062] Obtain the interfacial bonding strength parameter of the composite structure, generate a control command based on the deviation between the interfacial bonding strength parameter and the stress relief effect parameter of the stress-relieving structure, and use the control command to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-coupling effect, including: A peeling force is applied to the composite structure, and the critical peeling force value at which the copper-clad layer and the aluminum substrate separate at the interface is measured. The interface bonding strength parameter is calculated based on the critical peeling force value. A thermal cycling load is applied to the composite structure, and the change in residual stress at the metallurgical interface is measured. The stress relief effect parameter is calculated based on the change in residual stress. The strength deviation is determined based on the interface combined with the strength parameters and the preset strength target value, and the relief effect deviation is determined based on the stress relief effect parameters and the preset relief effect target value; Based on the intensity deviation, a first parameter adjustment amount is determined, and based on the mitigation effect deviation, a second parameter adjustment amount is determined, thereby generating the control command that includes the first parameter adjustment amount and the second parameter adjustment amount; The parameters in the physical morphology reconstruction process are adjusted according to the first parameter adjustment amount, and the parameters of the thermo-coupling effect are adjusted according to the second parameter adjustment amount.

[0063] When applying peel force to the composite structure, a 90° peel test method is used. The free end of the copper-clad layer is clamped in the grips of the tensile testing device, and a peel force is applied at a constant rate in a direction perpendicular to the surface of the aluminum substrate. During the peeling process, the force-displacement curve is recorded in real time. The peak load corresponding to the curve when there is a significant sudden drop in load or macroscopic separation of the copper-clad layer and the aluminum substrate is the critical peel force value. .Will Divide by the effective stripping width of the copper layer The interface bonding strength parameters per unit width are obtained. ,Right now The unit is N / m. This parameter directly reflects the resistance to delamination of the metallurgical interface in the vertical direction. The larger the value, the stronger the interfacial bond between the aluminum substrate and the copper clad layer.

[0064] When applying thermal cycling loads to the composite structure, the thermal cycling temperature range is set to cover the temperature range that the aluminum substrate and copper cladding layer would experience under actual service conditions, and the number of cycles is [not specified]. Based on reliability assessment requirements, the following parameters are defined: After each complete thermal cycle, the residual stress in the region near the metallurgical interface is measured using non-destructive testing methods such as X-ray diffraction stress testing or electron speckle interferometry. The change in residual stress at the metallurgical interface before and after the thermal cycle is defined as... ,based on Calculated stress relief effect parameters . Specifically, Characterized as the relative rate of change of interfacial residual stress during thermal cycling, i.e. ,in This represents the initial residual stress value at the metallurgical interface before thermal cycling. The smaller the value, the better the stress-relieving structure is at alleviating interfacial stress caused by differences in thermal expansion coefficients, and the higher the stability of the interface under thermal cycling conditions.

[0065] Obtain interface bonding strength parameters Then, compare it with the preset intensity target value. Compare and calculate the strength deviation. ,Right now .when When this occurs, it indicates that the current interface bonding strength does not meet the target requirements, and it is necessary to improve the anchoring effect of the microstructure layer by enhancing the physical morphology reconstruction process; when This indicates that the interfacial bonding strength has met the requirements. Similarly, the stress relief effect parameters... Compared with the preset target value of relief effect Compare and calculate the deviation in alleviating effects. ,Right now .when When this occurs, it indicates that the current stress relief effect is insufficient, and adjustments to the thermo-coupling parameters are needed to improve the performance of the stress-relieving structure; when When the stress relief effect reaches the target level, it indicates that the stress relief effect has been achieved.

[0066] Based on strength deviation Determine the adjustment amount of the first parameter At that time, a proportional adjustment strategy is adopted, that is ,in The first adjustment gain coefficient is obtained by calibrating empirical data on the sensitivity of interfacial bonding strength to physical morphology reconstruction processing. Specifically, these adjustments correspond to key parameters in the physical morphology reconstruction process, including laser power density adjustment, sandblasting pressure adjustment, or chemical etching time adjustment, and are determined based on the actual physical morphology reconstruction method used. This is based on mitigation effect deviation. Determine the adjustment amount of the second parameter At the same time, the proportional adjustment strategy is also adopted, that is ,in The second adjustment gain coefficient is obtained by calibrating based on empirical data on the sensitivity of the thermo-coupling effect parameters to the stress relief effect. Specifically, this corresponds to adjustments in annealing temperature, holding time, or applied pressure during thermo-coupling processes. and It is encapsulated as a control command and transmitted to the subsequent parameter adjustment execution stage.

[0067] Adjust the amount based on the first parameter. When adjusting the parameters in the physical topography reconstruction process, the current physical topography reconstruction parameter values ​​are used. Updated to The physical morphology reconstruction process was then re-executed with updated parameters to form a microstructure layer with more optimized hierarchical scale characteristics on the aluminum substrate surface. To improve the mechanical interlocking effect of the copper-clad layer on the aluminum substrate, the trench depth and surface roughness of the microstructure layer are increased by increasing the laser power density or extending the etching time, thereby enhancing the interfacial bonding strength. The adjustment amount is based on the second parameter. When adjusting the parameters of thermo-coupling, the current thermo-coupling parameter value is... Updated to Furthermore, by reapplying thermo-coupling to the composite structure with updated parameters, a stress-relieving structure with superior stress mitigation effect is obtained. By appropriately increasing the annealing temperature or extending the holding time, the compositional gradient in the intermetallic compound transition layer in the interface region can be further optimized, resulting in a smoother transition distribution of the thermal expansion coefficient between the aluminum substrate and the copper cladding layer, thereby reducing the degree of interface stress concentration during thermal cycling.

[0068] After completing the parameter adjustments and re-executing the relevant processing steps, the interface bonding strength parameters of the newly obtained composite structure and stress-relief structure were tested again. and stress relief effect parameters The measurement and calculation are performed, and the above deviation calculation and parameter adjustment process is repeated until... and The process continues until all preset convergence conditions are met. This closed-loop adaptive adjustment mechanism effectively addresses the impact of uncertainties such as differences in the properties of aluminum substrate materials from different batches and fluctuations in environmental temperature and humidity on the interface bonding quality. It ensures that the interface bonding strength and stress relief effect of each batch of composite structures consistently meet the design requirements, thereby significantly improving the overall reliability and consistency of aluminum substrate copper clad laminate products.

[0069] A second aspect of the present invention provides a system for enhancing the bonding strength of copper-clad laminates on an aluminum substrate, comprising: The morphology reconstruction unit is used to perform physical morphology reconstruction processing on the surface of the aluminum substrate, forming a microstructure layer with hierarchical scale characteristics on the surface of the aluminum substrate, and performing a deposition process on the surface of the microstructure layer to form an intermetallic compound transition layer, thereby obtaining an interface transition structure with a gradient composition distribution. A copper-clad deposition unit is used to deposit copper material on the interface transition structure to form a copper-clad layer, and to control the atomic diffusion behavior between the interface transition structure and the copper-clad layer, so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, thereby obtaining a composite structure. A stress relief unit is used to apply a thermo-coupling effect to the composite structure to obtain a stress relief structure. The stress relief structure is used to alleviate the interface stress caused by the difference in the thermal expansion coefficients between the aluminum substrate and the copper cladding layer. An adaptive adjustment unit is used to obtain the interface bonding strength parameter of the composite structure, generate a control command based on the deviation between the interface bonding strength parameter and the stress relief effect parameter of the stress release structure, and use the control command to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-coupling effect.

[0070] A third aspect of the present invention provides an electronic device, comprising: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0071] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0072] This invention can be a method, apparatus, system, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of the invention.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for enhancing the bonding strength of copper-clad laminates on aluminum substrates, characterized in that, include: The surface of the aluminum substrate is subjected to physical morphology reconstruction treatment to form a microstructure layer with hierarchical scale characteristics on the surface of the aluminum substrate. An intermetallic compound transition layer is formed on the surface of the microstructure layer by deposition treatment to obtain an interface transition structure with gradient composition distribution. A copper-clad layer is formed by depositing copper material on the interface transition structure, and the atomic diffusion behavior between the interface transition structure and the copper-clad layer is controlled so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, resulting in a composite structure. A stress-relieving structure is obtained by applying a thermo-coupling effect to the composite structure. The stress-relieving structure is used to alleviate the interfacial stress caused by the difference in the thermal expansion coefficients between the aluminum substrate and the copper cladding layer. The interface bonding strength parameter of the composite structure is obtained, and an adjustment command is generated based on the deviation between the interface bonding strength parameter and the stress relief effect parameter of the stress release structure. The adjustment command is used to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-mechanical coupling effect.

2. The method according to claim 1, characterized in that, The surface of an aluminum substrate undergoes physical morphology reconstruction to form a microstructure layer with hierarchical scale characteristics. An intermetallic compound transition layer is then deposited on the surface of this microstructure layer, resulting in an interface transition structure with a gradient composition distribution, including: Mechanical energy is applied to the surface of the aluminum substrate to obtain a first-scale morphological feature, which is used to provide a macroscopic anchoring effect. Chemical energy is applied to the surface of the first-scale morphological feature to obtain the second-scale morphological feature. The second-scale morphological feature is used to increase the interfacial contact area. The first-scale morphological feature and the second-scale morphological feature constitute the microstructure layer of the hierarchical morphological feature. A surface modification treatment is applied to the surface of the microstructure layer so that the surface energy state of the microstructure layer satisfies the interface wetting constraint condition, thereby obtaining a microstructure layer with regulated surface energy. Based on the surface tension state of the microstructure layer after surface energy regulation and the lattice parameters of the aluminum substrate and the copper layer to be coated, the compositional gradient sequence of the intermetallic compound material is determined. Intermetallic compound materials are sequentially deposited on the surface of the microstructure layer after surface energy modulation according to the composition gradient sequence to form the intermetallic compound transition layer. The lattice structure of the intermetallic compound transition layer changes continuously along the thickness direction to obtain the interface transition structure.

3. The method according to claim 2, characterized in that, A surface modification treatment is applied to the surface of the microstructure layer to make the surface energy state of the microstructure layer satisfy the interface wetting constraint condition, thereby obtaining a surface energy-modulated microstructure layer, including: Elemental composition detection and chemical bond state analysis are performed on the surface of the microstructure layer to obtain elemental distribution information and chemical bond state information of the surface of the microstructure layer; Based on the elemental distribution information and the chemical bond state information, the surface tension value and surface active site density of the microstructure layer surface are calculated. The surface tension value is used to characterize the wettability of the microstructure layer surface, and the surface active site density is used to characterize the number of active sites on the microstructure layer surface available for chemical reactions. Based on the surface tension value and the surface active site density, and in conjunction with the target surface tension range and target active site density range indicated in the interface wetting constraint conditions, the modification intensity parameter and modification coverage range parameter of the surface modification treatment are determined. The surface of the microstructure layer is processed according to the modification intensity parameter and the modification coverage parameter, so that the surface tension value of the microstructure layer surface enters the target surface tension range and the surface active site density enters the target active site density range, thereby obtaining the microstructure layer after surface energy regulation.

4. The method according to claim 1, characterized in that, A copper-clad layer is formed by depositing copper material on the interface transition structure, and the atomic diffusion behavior between the interface transition structure and the copper-clad layer is controlled, so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, resulting in a composite structure, including: Based on the thickness distribution and crystal structure information of the intermetallic compound transition layer, the copper material deposition temperature parameters and copper material deposition rate parameters are determined. Copper material is deposited on the surface of the interface transition structure according to the copper material deposition temperature parameters and the copper material deposition rate parameters to form the copper cladding layer; During the formation of the copper clad layer, the interfacial atomic concentration distribution between the interface transition structure and the copper clad layer is monitored to obtain diffusion flux information between the intermetallic compound transition layer and the copper clad layer. Based on the diffusion flux information, the copper material deposition temperature parameters are adjusted to allow atoms between the intermetallic compound transition layer and the copper cladding layer to diffuse into each other to meet the preset diffusion equilibrium conditions. While satisfying the preset diffusion equilibrium conditions, the copper plating deposition process is maintained, allowing atoms between the intermetallic compound transition layer and the copper plating layer to diffuse into each other to form atomic bonding regions. These atomic bonding regions constitute the metallurgical bonding interface, resulting in the composite structure.

5. The method according to claim 4, characterized in that, Adjusting the copper material deposition temperature parameters based on the diffusion flux information to allow atomic interdiffusion between the intermetallic compound transition layer and the copper cladding layer to meet a preset diffusion equilibrium condition includes: Based on the diffusion flux information, calculate the first diffusion flux value of metal atoms in the intermetallic compound transition layer diffusing to the copper clad layer and the second diffusion flux value of copper atoms in the copper clad layer diffusing to the intermetallic compound transition layer; Calculate the diffusion flux ratio between the first diffusion flux value and the second diffusion flux value, and compare the diffusion flux ratio with a preset diffusion equilibrium ratio to calculate the deviation between the diffusion flux ratio and the preset diffusion equilibrium ratio; The temperature adjustment amount of the copper material deposition temperature parameter is determined based on the relationship between the deviation and the diffusion flux temperature response. The current copper material deposition temperature parameter is then processed based on the temperature adjustment amount to obtain the updated copper material deposition temperature parameter. The copper deposition process is controlled according to the updated copper material deposition temperature parameters, and the diffusion flux ratio is recalculated. When the deviation between the diffusion flux ratio and the preset diffusion equilibrium ratio meets the preset convergence threshold, it is confirmed that the inter-atomic diffusion satisfies the preset diffusion equilibrium condition.

6. The method according to claim 1, characterized in that, Applying a thermo-coupling effect to the composite structure yields a stress-relieving structure, comprising: Stress field distribution is detected at the metallurgical bonding interface of the composite structure to obtain interface stress distribution information and stress concentration area information of the metallurgical bonding interface. Based on the interface stress distribution information and the stress concentration region information, the thermal field parameters and force field parameters are determined. The composite structure is processed according to the thermal field parameters to activate the atomic diffusion behavior at the metallurgical interface, so that the interface atoms between the aluminum substrate and the intermetallic compound transition layer and between the intermetallic compound transition layer and the copper cladding layer diffuse into each other. The atomic bonding density at the metallurgical interface is made to reach a preset target value by means of atomic diffusion behavior, and the composite structure is processed according to the force field parameters to trigger dislocation movement in the stress concentration region and obtain the stress relief structure.

7. The method according to claim 1, characterized in that, Obtain the interfacial bonding strength parameter of the composite structure, generate a control command based on the deviation between the interfacial bonding strength parameter and the stress relief effect parameter of the stress-relieving structure, and use the control command to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-coupling effect, including: A peeling force is applied to the composite structure, and the critical peeling force value at which the copper-clad layer and the aluminum substrate separate at the interface is measured. The interface bonding strength parameter is calculated based on the critical peeling force value. A thermal cycling load is applied to the composite structure, and the change in residual stress at the metallurgical interface is measured. The stress relief effect parameter is calculated based on the change in residual stress. The strength deviation is determined based on the interface combined with the strength parameters and the preset strength target value, and the relief effect deviation is determined based on the stress relief effect parameters and the preset relief effect target value; Based on the intensity deviation, a first parameter adjustment amount is determined, and based on the mitigation effect deviation, a second parameter adjustment amount is determined, thereby generating the control command that includes the first parameter adjustment amount and the second parameter adjustment amount; The parameters in the physical morphology reconstruction process are adjusted according to the first parameter adjustment amount, and the parameters of the thermo-coupling effect are adjusted according to the second parameter adjustment amount.

8. An aluminum substrate copper-clad layer bonding strength enhancement system for implementing the method as described in any one of claims 1-7, characterized in that, include: The morphology reconstruction unit is used to perform physical morphology reconstruction processing on the surface of the aluminum substrate, forming a microstructure layer with hierarchical scale characteristics on the surface of the aluminum substrate, and performing a deposition process on the surface of the microstructure layer to form an intermetallic compound transition layer, thereby obtaining an interface transition structure with a gradient composition distribution. A copper-clad deposition unit is used to deposit copper material on the interface transition structure to form a copper-clad layer, and to control the atomic diffusion behavior between the interface transition structure and the copper-clad layer, so that the intermetallic compound transition layer forms a metallurgical bonding interface between the aluminum substrate and the copper-clad layer, thereby obtaining a composite structure. A stress relief unit is used to apply a thermo-coupling effect to the composite structure to obtain a stress relief structure. The stress relief structure is used to alleviate the interface stress caused by the difference in the thermal expansion coefficients between the aluminum substrate and the copper cladding layer. An adaptive adjustment unit is used to obtain the interface bonding strength parameter of the composite structure, generate a control command based on the deviation between the interface bonding strength parameter and the stress relief effect parameter of the stress release structure, and use the control command to adaptively adjust the parameters of the physical morphology reconstruction process and the thermo-coupling effect.

9. An electronic device, characterized in that, include: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the method described in any one of claims 1 to 7.

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