High-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate and multi-physical field design method thereof

Abstract

The invention discloses a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate and a multi-physical field design method thereof, and belongs to the technical field of functional materials. The substrate comprises an aluminum nitride plate body, and a plurality of square or rectangular groove bodies are formed in the surface of the aluminum nitride plate body in an array mode. Each groove body is filled with a diamond copper composite material; wherein an active metal brazing layer is arranged between the diamond-copper composite material and the inner wall of the tank body. The high-temperature-resistant, low-dielectric and high-heat-conducting performance collaboration is achieved, the research and development cost and period are reduced through the simulation design, and the high-temperature-resistant and high-temperature-resistant composite material is suitable for high-frequency

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional materials, and relates to a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate and a multi-physical field design method thereof. BACKGROUND

[0002] In high-end fields such as 5G communication, aerospace and new energy vehicles, the working environment of core devices such as thin film circuits, high-frequency thin film antennas and high-power chips is developing towards “high frequency, high temperature and high power density”, which puts forward requirements of high temperature resistance (150-200℃), high thermal conductivity (≥300W / m·K), high structural reliability and high frequency signal compatibility for functional substrate materials. However, the current substrate material technology system has significant performance short boards, and it is difficult to meet the application requirements of multi-dimensional performance coordination.

[0003] Firstly, a single material cannot meet multiple performance requirements, and there is a “performance seesaw” dilemma. For example, insulating ceramic substrates (such as silicon nitride and aluminum nitride) have excellent high-temperature resistance (temperature resistance ≥800℃) and low dielectric properties (alumina εr≤9, aluminum nitride εr≤10), but the thermal conductivity is poor (alumina ≤30W / m·K, aluminum nitride ≤200W / m·K). When high-power devices (such as 100W / cm² heat flow density scenario) work, heat cannot be conducted in time, which easily forms local hot spots, leading to signal transmission distortion, shortening of device life, and even direct burning, which cannot adapt to high-temperature application scenarios such as aerospace and automotive electronics. The thermal conductivity of high-thermal-conductivity metal matrix composites (such as diamond copper composites) can reach more than 450W / m·K, and the heat dissipation capacity is outstanding, but the completely conductive characteristics make the dielectric constant lose practical application significance, and the electromagnetic loss is extremely large at 1-40GHz high frequency band, which will seriously absorb and attenuate signals, and cannot meet the insulation and low loss requirements of high-frequency circuits. It can only be used as a heat dissipation accessory, not as a substrate main body. The existing composite substrate adopts a simple superimposed structure of “insulating layer + high-thermal-conductivity layer”, which is prone to structural failure problems such as peeling, delamination and the like under high-temperature working conditions. A new type of low-dielectric high-thermal-conductivity substrate is urgently needed for high-temperature high-frequency thin film circuit substrate applications.

[0004] In addition, the design mode is inefficient, and the "physical trial and error" leads to high cost and long cycle of industrialization. The current structure optimization and performance verification of the composite substrate excessively rely on the traditional mode of "design-sample preparation-physical test". The test cost is high, and special equipment such as high-frequency dielectric spectrum analyzer, high-temperature thermal conductivity tester and high-temperature stress fatigue testing machine needs to be purchased, and the cost of a single equipment is more than one million yuan, which is difficult for small and medium-sized enterprises to bear; the research and development cycle is long, and the preparation of a single physical sample needs 7-15 days, plus the performance test cycle, a set of parameter verification needs more than 20 days, if 10 groups of parameters need to be iterated, the research and development cycle will exceed half a year; it is difficult to lock the parameters, and there is a lack of accurate virtual verification means, the coupling effect of structure parameters on thermal and mechanical properties cannot be predicted through simulation, and it is difficult to lock the optimal parameter combination, which seriously hinders the industrialization process of the product.

[0005] In summary, the existing substrate material has significant shortcomings in performance coordination, structure reliability and research and development efficiency, and it has become a key technical problem to be solved in the field of high-end electronic devices to develop a composite substrate structure that can meet the multi-performance requirements of high-frequency and high-temperature scenes and to build an efficient simulation design method. SUMMARY

[0006] To solve the problems in the background art, mainly aiming at the bottleneck that the existing functional substrate material is difficult to coordinate in high-temperature resistance, low dielectric, low electromagnetic loss and high thermal conductivity performance, the present application provides a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate and a multi-physical field design method thereof. The method builds a set of simulation-based design method, which does not need to rely on a large number of physical tests, but can quickly and accurately lock the optimal structure parameters of the composite functional substrate material through virtual verification, thereby reducing the research and development cost, accelerating the application and transformation of the functional substrate material to the product field such as thin film circuit and thin film antenna, and promoting the development of related industries.

[0007] The first object of the present application provides a multi-physical field design method of a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate, comprising: designing a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate according to target requirements, wherein the substrate comprises an aluminum nitride plate body, and a plurality of square or rectangular groove bodies are arrayed on the surface of the aluminum nitride plate body; each groove body is filled with diamond copper composite material; and an active metal brazing layer is arranged between the diamond copper composite material and the inner wall of the groove body; The bottom corners of each groove body are provided with a round corner structure, and the radius R of the round corner is 20-30 μm; The inner wall of each groove body is roughened, and the surface roughness Ra is 0.8-1.2 μm; A parameterized model of the rectangular slot type diamond copper-aluminum nitride composite functional substrate is constructed based on a finite element analysis software, and core parameters are defined; The grid is divided by local encryption, wherein a boundary layer is refined for each slot region and the active metal brazing layer region in each slot; Thermal simulation of the substrate: input the thermal performance parameters of aluminum nitride, diamond copper and the brazing layer, apply surface heat flux to simulate chip heating, set the environment temperature boundary at the bottom, and output the overall thermal conductivity; Mechanical simulation of the substrate: the temperature field of the thermal simulation is introduced as a load into the structural mechanics module to calculate thermal stress and deformation displacement, and the interface shear stress is monitored at the same time; According to the interface shear stress at the highest working temperature and the thermal conductivity at room temperature, an evaluation function is defined; The variables in the evaluation function are optimized by using a genetic algorithm to screen the core parameter combination that meets the target requirements, and an optimal parameter report of the substrate is output.

[0008] In an embodiment, the thermal conductivity qualified threshold that meets the target requirements is room temperature thermal conductivity≥300W / m·K; the interface shear stress qualified threshold is interface shear stress at the highest working temperature<100MPa.

[0009] In an embodiment, the core parameters include substrate thickness, slot side length, slot spacing, slot depth, slot inner fillet radius and brazing layer thickness.

[0010] In an embodiment, the evaluation function is: F=ω1×(σ_max)+ω2×(T_junction) Wherein, σ_max is the interface shear stress score at the highest working temperature, wherein 30MPa is 10 points, and decreases by 7MPa / point; the weight ω1≥0.6; T_junction is the thermal conductivity score at room temperature, wherein 500W / m·K is 10 points, and decreases by 20W / m·K / point; the weight ω2=0.2-0.4.

[0011] In an embodiment, during the optimization process of the variables in the evaluation function, the qualified threshold is set as F≥0, σ_max≥0, and T_junction≥0.

[0012] In an embodiment, the dielectric constant εr of the aluminum nitride plate body is 7-10, the thermal conductivity is 100-200W / m·K, and the thermal expansion coefficient is 2.5-5×10 -6 / K.

[0013] In an embodiment, the thermal conductivity of the diamond copper composite material is 400-700W / m·K, and the thermal expansion coefficient is 6.5-9×10-6 The diamond copper composite material has a diamond volume fraction of 35-45%, and the particle size of the diamond is 100-300 mu m.

[0014] In an embodiment, the brazing filler material for preparing the active metal brazing layer is Ag72-Cu28-Ti0.5; the thickness of the active metal brazing layer is 5-10 mu m, the interface thermal resistance is less than or equal to 15 m2*K / W, and the interface shear strength is greater than or equal to 100 MPa.

[0015] In an embodiment, when the genetic algorithm is used to optimize the variables in the evaluation function, the population size is greater than or equal to 50, and the number of iterations is greater than or equal to 30.

[0016] The second object of the present application is to provide a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate.

[0017] The present application has the following beneficial effects: The present application provides a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate and a multi-physical field design method. The substrate provided by the present application adopts an "embedded thermal core" design concept, uses aluminum nitride ceramic as an insulating substrate to achieve low dielectric, and opens parallel square grooves containing stress buffer fillets and rough wall surfaces on the surface. The continuous heat conduction channel is formed by filling the groove with diamond copper composite material through the active metal brazing layer to achieve high thermal conductivity. The simulation design method includes parameterized modeling, thermal-mechanical coupling simulation and multi-objective optimization, and the optimal parameters are selected by the evaluation function F=ω1*(σ_max)+ω2*(T_junction). The substrate designed by the present application has an aluminum nitride substrate thickness of 600-1500 mu m, a square groove side length of 200-500 mu m, a groove spacing of 100-200 mu m, a groove depth of 200-500 mu m, a groove bottom fillet radius of 20-30 mu m, and a groove wall roughness Ra=0.8-1.2 mu m; the diamond copper has an optimal volume fraction of 35-45%, and the thermal conductivity is 400-700 W / m*K; and the brazing layer has a thickness of 5-10 mu m. The present application realizes the performance synergy of high-temperature resistance, low dielectric, and high thermal conductivity, reduces the research and development cost and cycle through simulation design, and is suitable for high-frequency high-temperature application scenarios.

[0018] The diamond copper and the aluminum nitride provided by the present application form a composite functional structure through a metallurgical bond of the active metal brazing layer, and realize the synergy of "low dielectric support + high-efficiency heat dissipation".

[0019] The substrate provided by the present application is used to bond the components and thin film circuits on the positive surface of the aluminum nitride, and performs electrical signal transmission, which can realize low dielectric loss.

[0020] The present application is verified by multi-physical field simulation, and the designed substrate can effectively meet the threshold requirements of normal temperature thermal conductivity greater than or equal to 300 W / m*K and high-temperature interface shear stress less than or equal to 100 MPa.

[0021] Compared with the prior art, the application also includes the following effects: Structural innovation advantage: simulation verification shows that the thermal conductivity is significantly improved compared with the same size single aluminum nitride ceramic, which meets the signal transmission and heat dissipation needs of high-temperature, high-power and high-frequency thin film circuits.

[0022] R&D efficiency advantage: full-process simulation design reduces the dependence on physical testing, reduces R&D cost and shortens the cycle.

[0023] Achievements transformation advantage: the structure is compatible with existing processes such as laser processing, magnetron sputtering and vacuum brazing, without the need for special equipment, which is conducive to large-scale production and has broad prospects for industrialization in the fields of thin film circuit substrates and high-frequency antenna substrates. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a two-dimensional cross-sectional view of the overall diamond copper-aluminum nitride composite functional substrate.

[0025] Figure 2 It is a two-dimensional cross-sectional view of the overall diamond copper-aluminum nitride composite functional substrate.

[0026] Figure 3 It is a local enlarged view of the groove bottom fillet.

[0027] Figure 4 It is an application schematic diagram of the diamond copper-aluminum nitride composite functional substrate.

[0028] Figure 5 It is a multi-physical field collaborative simulation design flowchart.

[0029] Figure 6 It is a three-dimensional schematic diagram of the overall diamond copper-aluminum nitride composite functional substrate material of Example 1.

[0030] Figure 7 It is a thermal simulation diagram of Example 1.

[0031] Figure 8 It is an interface shear mechanics simulation diagram of Example 1.

[0032] Figure 9 It is a two-dimensional cross-sectional view of the overall diamond copper-aluminum nitride composite functional substrate material of Example 2.

[0033] Figure 10 It is a thermal simulation diagram of Example 2.

[0034] Figure 11 It is an interface shear mechanics simulation diagram of Example 2. DETAILED DESCRIPTION

[0035] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0036] The present application aims at the bottleneck that the existing functional substrate material is difficult to coordinate in high-temperature resistance, low dielectric, low electromagnetic loss and high thermal conductivity performance, provides a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate, constructs a set of simulation-based design method, without relying on a large number of physical tests, only through virtual verification can quickly and accurately lock the optimal structure parameters of the composite functional substrate material, thereby reducing the research and development cost, accelerating the application and transformation of functional substrate material to product fields such as thin film circuit and thin film antenna, and promoting the development of related industries.

[0037] The present application breaks through the performance coordination and research and development efficiency bottleneck of the existing substrate material through the trinity design of "structure innovation + process adaptation + simulation optimization", specifically including three parts of new structure design of composite substrate, supporting preparation process and multi-physical field simulation design method, and realizes the functional coordination of "low dielectric support + efficient heat dissipation + high-temperature reliability".

[0038] It should be noted that the diamond copper composite material is a copper-based composite material prepared by using metal copper as a continuous phase matrix and high-thermal-conductivity artificial diamond particles as a reinforcing phase through a specific powder metallurgy or composite process.

[0039] In order to achieve the above purpose, a multi-physical field design method of a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate, comprising: According to the target requirement, a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate is designed, a parameterized model of the rectangular groove type diamond copper-aluminum nitride composite functional substrate is constructed based on a finite element analysis software, and core parameters are defined; Local encryption is adopted for mesh division, wherein a boundary layer refinement is set for each groove region and the active metal brazing layer region in each groove; Thermal simulation of the substrate: input the thermal performance parameters of aluminum nitride, diamond copper and the brazing layer, apply a surface heat flux to simulate chip heating, set an environmental temperature boundary at the bottom, and output the overall thermal conductivity; Mechanical simulation of the substrate: the thermal simulation temperature field is introduced as a load into the structural mechanics module to calculate thermal stress and deformation displacement, and at the same time, the interface shear stress is monitored; The thermal conductivity qualified threshold is that the thermal conductivity at room temperature is greater than or equal to 300 W / m K; and the interface shear stress qualified threshold is that the interface shear stress at the highest working temperature is less than 100 MPa. According to the interface shear stress at the highest working temperature and the thermal conductivity at room temperature, an evaluation function is defined. The variables in the evaluation function are optimized by using a genetic algorithm, and a core parameter combination that meets all the thresholds is screened, and an optimal parameter report is output.

[0040] The core parameters include the substrate thickness, the slot side length, the slot spacing, the slot depth, the slot inner corner radius, and the brazing layer thickness.

[0041] The evaluation function is: F = ω1× (σ_max) + ω2×(T_junction) In the formula, σ_max is the interface shear stress score at the highest working temperature, wherein 30 MPa is 10 points, and decreases by 7 MPa / point; the weight ω1 is greater than or equal to 0.6; T_junction is the thermal conductivity score at room temperature, wherein 500 W / m K is 10 points, and decreases by 20 W / m K / point; and the weight ω2 is 0.2-0.4.

[0042] Specifically, a high-temperature-resistant low-dielectric rectangular slot type diamond copper-aluminum nitride composite functional substrate includes an aluminum nitride plate body, and a plurality of square or rectangular slots are arranged on the surface of the aluminum nitride plate body; each slot is filled with diamond copper composite material; and an active metal brazing layer is arranged between the diamond copper composite material and the inner wall of the slot.

[0043] The bottom corners of each slot are provided with a round corner structure, and the round corner radius R is 20-30 μm.

[0044] The side length of each slot is 200-500 μm; The spacing between adjacent slots is 100-200 μm; The depth of each slot is 200-500 μm; The tolerance between the diamond copper composite material filled in each slot and the slot is less than or equal to ±5 μm.

[0045] The thickness of the aluminum nitride plate body is 600-1500 μm.

[0046] The dielectric constant εr of the aluminum nitride plate body is 7-10, the thermal conductivity is 100-200 W / m K, and the thermal expansion coefficient is 2.5-5×10 -6 / K.

[0047] The inner wall of each groove is roughened, and the surface roughness Ra is 0.8-1.2 μm.

[0048] The thermal conductivity of the diamond copper composite material is 400-700 W / m·K, and the thermal expansion coefficient is 6.5-9×10 -6 / K;The volume fraction of diamond in the diamond copper composite material is 35-45%, and the particle size of diamond is 100~300 μm.

[0049] The brazing material for preparing the active metal brazing layer is Ag72-Cu28-Ti0.5; The thickness of the active metal brazing layer is 5-10 μm, the interface thermal resistance is ≤15 m²·K / W, and the interface shear strength is ≥100 MPa.

[0050] It should be noted that the diamond copper composite material is called diamond copper inlay block.

[0051] Referring to Figures 1-2 As shown in the figure, a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate includes an AlN substrate and a plurality of square or rectangular grooves arrayed on the surface of the AlN substrate, and each groove is filled with diamond copper. Referring to Figure 3 As shown in the figure, the bottom corners of each groove are provided with a round corner structure, and the round corner radius R is 25 μm. Referring to Figure 4 As shown in the figure, the high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate is arranged on a chip, and the arrayed grooves are away from the side of the chip.

[0052] The present application adopts the "embedded thermal core" core idea, and the aluminum nitride is responsible for insulation and low-dielectric signal transmission, and the diamond copper is responsible for core heat dissipation. The aluminum nitride insulating substrate is used as the main frame of the substrate, and the thickness H is 600-1500 μm. -6 The high-purity aluminum nitride ceramic (purity ≥ 99.5%) has a dielectric constant εr=7-10 (1-40 GHz frequency band), a thermal conductivity =100-200 W / m·K, and a thermal expansion coefficient CTE=2.5-5×10

[0053] The base surface is provided with an array of square or rectangular grooves, and the groove structure parameters are as follows: the groove depth is 200-500 μm to ensure that the diamond copper forms an effective heat conduction channel after filling, and the groove does not penetrate the base to affect insulation; the groove side length is 200-500 μm, and the groove spacing is 100-200 μm to separate the conductive area of the diamond copper through the aluminum nitride to ensure overall insulation; the groove bottom is provided with an R=20-30 μm stress buffer round corner to disperse local stress at high temperature and avoid stress concentration to cause the base to crack; and the groove wall is roughened, and the surface roughness Ra is preferably 0.8-1.2 μm to improve the bonding force with the subsequent brazing layer.

[0054] The diamond copper embedded block is filled in the rectangular groove to form a continuous strip-shaped heat conduction channel. The volume fraction of diamond in the diamond copper is preferably 35-45%, the thermal conductivity is 420-700 W / m·K, the thermal expansion coefficient is 6.5-9×10 -6 / K, and the CTE difference with aluminum nitride is as small as possible; the size of the embedded block is completely complementary to the rectangular groove, and the tolerance is ≤±5 μm, so that there is no gap after filling and the interfacial thermal resistance is reduced.

[0055] The active metal brazing layer is located between the aluminum nitride base and the diamond copper embedded block, and the thickness is 5-10 μm. The brazing layer is preferably Ag-Cu-Ti filler (Ag72-Cu28-Ti0.5, melting point 780°C), which realizes high-strength and low-resistance connection of the two through metallurgical bonding. The brazing layer can eliminate the interface gap and reduce the interfacial thermal resistance to ≤15 m 2 ·K / W, and the Ti element can react with Al2O3 on the surface of the aluminum nitride to form a Ti-Al-O compound, thereby improving the interfacial bonding strength (shear strength ≥100 MPa) and solving the problem of interface peeling at high temperature.

[0056] For example, a multi-physical field synergistic simulation design method of a high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate includes the following steps: A full-process design method of "parameterized modeling-multi-field coupled simulation-automatic optimization" is constructed, and the optimal parameters can be quickly locked without physical trial and error. Referring to Figure 5 The specific steps are as follows: S1, parameterized three-dimensional model construction Based on a finite element analysis software such as ANSYS, COMSOL, etc., a parameterized model of "aluminum nitride base-brazing layer-diamond copper embedded block" is established, and the core variables are defined: the aluminum nitride base thickness H (600-1500 μm), the square groove side length W (200-500 μm), the groove spacing S (100-200 μm), the groove depth h (200-500 um), the groove bottom round corner R=20-30 μm stress buffer round corner, and the brazing layer thickness T (5-10 μm).

[0057] Material parameters of the aluminum nitride substrate, aluminum nitride substrate, and brazing filler material, and the thermal conductivity, thermal expansion coefficient, and interface thermal resistance of each material are set.

[0058] The meshing adopts a "local encryption" strategy to ensure the simulation accuracy of the microstructure and balance the accuracy and efficiency: the boundary layer is refined in the rectangular groove and the interface area of the brazing layer to improve the simulation accuracy of the interface and control the single model calculation time to ≤3 hours.

[0059] S2, thermal-mechanical multi-field coupling simulation Thermal simulation: input material thermal performance parameters; simulate actual working conditions, input environmental temperature, and apply surface heat flux density on the upper layer of the substrate to simulate high-power chip heating; set the environmental temperature boundary condition at the bottom of the substrate; output the overall thermal conductivity. The qualified threshold is set to be the room temperature thermal conductivity ≥300W / m·K.

[0060] Mechanical simulation: the temperature field of the thermal simulation is directly imported into the structural mechanics module as a load to calculate the thermal stress field and deformation displacement field, and the stress distribution of the inverted corner structure at the groove bottom edge is monitored. The qualified threshold is that the interface shear stress at the highest working temperature is <100MPa.

[0061] S3, multi-objective parameter automatic optimization The evaluation function is defined as F = ω1× (σ_max) + ω2×(T_junction), and the qualified threshold is set to F≥0 In the formula, σ_max is the interface shear stress score at the highest working temperature, wherein 30MPa is 10 points, and decreases by 7MPa per point, that is, based on 30MPa, every increase of 7MPa decreases the score by 1 point; the weight ω1≥0.6, which prioritizes structural reliability; and the qualified threshold is set to σ_max≥0. T_junction is the thermal conductivity score at room temperature, wherein 500W / m·K is 10 points, and decreases by 20W / m·K per point, that is, based on 500W / m·K, every decrease of 20W / m·K decreases the score by 1 point, and the weight ω2=0.2-0.4, which ensures the working temperature of the device.

[0062] The weight increases when used at high temperature and high power, and is specifically selected according to actual application requirements; and the qualified threshold is set to T_junction≥0.

[0063] Genetic algorithm is adopted, the population size is ≥50, the iteration number is ≥30, and the variables in F are optimized to automatically select the parameter combination that meets the qualified threshold of thermal and mechanical properties and the evaluation function F threshold. Finally, an optimal parameter report containing "substrate thickness-groove length / depth-groove spacing" is output to directly guide the actual preparation.

[0064] In the actual preparation process, the substrate is prepared in a process, which comprises: The process is fully compatible with existing ceramic processing and metal bonding technology, without the need for customizing special equipment, and the specific steps are as follows: Aluminum nitride substrate processing: femtosecond laser processing square groove, sandblasting groove wall to Ra=0.8-1.2μm, ultrasonic cleaning impurities.

[0065] Diamond copper block preparation: diamond copper body is prepared by powder metallurgy or infiltration method, and the block is precisely CNC processed to ensure that the size is complementary to the rectangular groove (tolerance ±5μm).

[0066] Interface bonding and post-processing: first, a Ti / Cu / Ni metal layer is deposited on the groove wall and the block surface by magnetron sputtering; second, vacuum brazing is performed, Ag-Cu-Ti filler foil is laid, and metallurgical bonding is achieved at 850℃ for 15min; finally, the substrate surface is polished (flatness≤5μm). In the diamond copper block used in the following examples, the volume fraction of diamond is 40%, and the particle size of diamond is 200μm.

[0067] In order to illustrate the high-temperature-resistant low-dielectric rectangular groove type diamond copper-aluminum nitride composite functional substrate and multi-physical field synergistic simulation design method provided by the present application, the following specific embodiments are described.

[0068] Example 1 A design method of a 10GHz high-power thin film circuit composite functional substrate, comprising: (1) Target demand Adapt to 10GHz frequency band thin film circuit, thin film circuit size 3*3mm, high temperature 200℃ working condition, meet the heat dissipation demand under 100W / cm² heat flux density.

[0069] Core index: thermal conductivity≥300W / m·K at room temperature, interface shear strength≤100MPa at 200℃ working condition.

[0070] (2) Material parameter design Aluminum nitride substrate: the corresponding thermal conductivity at room temperature, 100℃, 200℃ is 220W / m·K, 180W / m·K, 140 W / m·K, and the corresponding CTE is 2.5×10 -6 / K, 3.55×10 -6 / K, 4.36×10 -6 / K, dielectric constant εr=8.8; Diamond copper block: the corresponding thermal conductivity at room temperature, 100℃, 200℃ is 650W / m·K, 550W / m·K, 450 W / m·K, and the corresponding CTE is 5.35×10-6 / K, 5.56 x 10 -6 / K, 7 x 10 -6 / K.

[0071] Ag72-Cu28-Ti0.5 filler material, thickness 7 pm, interface thermal resistance 15 m2K / W.

[0072] (3) Structure parameter design After multi-physics field simulation optimization, the structure size of the composite functional substrate material is confirmed: the thickness of the aluminum base H = 635 pm, the square groove side length W = 300 pm, the groove depth h = 300 pm, the groove spacing S = 150 pm, and the groove bottom round angle R = 25 pm. The overall three-dimensional structure diagram of the substrate material is shown in FIG. 1. Figure 6

[0073] (4) Simulation verification Thermal performance: Table 1 presents the thermal conductivity performance comparison of the diamond copper-aluminum nitride composite functional substrate material and single aluminum oxide ceramic material and single aluminum nitride ceramic under the same size. The room temperature thermal conductivity is 302.69 W / mK, 30 W / mK, and 200 W / mK, respectively. Compared with single aluminum oxide and aluminum nitride ceramic, the diamond copper embedded structure significantly improves the thermal conductivity of the composite functional substrate, reaching the index of thermal conductivity ≥ 300 W / mK at room temperature. The thermal conductivity of the diamond copper-aluminum nitride composite functional substrate material provided in this embodiment is 192.41 W / mK at 200°C working condition. Figure 7 The overall temperature distribution under 100 W / cm2 heat flux density at 200°C working condition is presented.

[0074] Table 1 Thermal conductivity performance comparison of the diamond copper-aluminum nitride composite functional substrate material and single aluminum oxide ceramic material and single aluminum nitride ceramic under the same size of Example 1

[0075] Mechanical performance: Figure 8 The diamond copper interface shear stress condition at 200°C working condition is presented. It can be seen that the maximum interface shear stress of the diamond copper insertion structure is about 83 MPa, which is lower than the AlN / diamond copper interface shear stress threshold (≤ 100 MPa), effectively avoiding the interface peeling problem at high temperature.

[0076] (5) Conclusion The diamond copper-aluminum nitride composite functional substrate material with the parameter combination H = 635 pm, W = 300 pm, h = 300 pm, and S = 150 pm can meet the index requirements of room temperature thermal conductivity ≥ 300 W / mK, 200°C working condition interface shear strength ≤ 100 MPa, and evaluation function F ≥ 0, serving as an optimized scheme for 10 GHz high-power thin film circuit substrate. ​

[0077] Embodiment 2 A design method of a composite functional substrate for a 28GHz high-frequency thin film antenna, comprising: (1) Target demand Adapt to 5G communication 28GHz frequency band thin film antenna, antenna thin film circuit size 5*5mm, guarantee low loss transmission of high frequency signal, at the same time meet the heat dissipation demand under 80W / cm² heat flux density of high temperature 100℃ working condition.

[0078] Core index: thermal rate≥300W / m·K at room temperature, interface shear strength≤100MPa under 100℃ working condition.

[0079] (2) Material parameter design Aluminum nitride substrate: the corresponding thermal conductivity is 220W / m·K, 180W / m·K, 140W / m·K at room temperature, 100℃, 200℃ respectively, and the corresponding CTE is 2.5×10 -6 / K, 3.55×10 -6 / K, 4.36×10 -6 / K, dielectric constantεr=8.8; Diamond copper block: the corresponding thermal conductivity is 650W / m·K, 550W / m·K, 450W / m·K at room temperature, 100℃, 200℃ respectively, and the corresponding CTE is 5.35×10 -6 / K, 5.56×10 -6 / K, 7×10 -6 / K.

[0080] Ag72-Cu28-Ti0.5solder, thickness 7μm, interface thermal resistance 15m²·K / W.

[0081] (3) Structure parameter design: After multi-physics field simulation optimization, it is confirmed that the structure size of the composite functional substrate material is: the thickness of the aluminum nitride substrate H=635μm, the square groove side length W=300μm, the groove depth h=250μm, the groove spacing S=150μm, and the groove bottom round angle R=25μm. The overall three-dimensional structure of the substrate material is as shown in Figure 9 .

[0082] (4) Multi-physics field simulation result Thermal Properties: Table 2 presents a comparison of the thermal conductivity of the diamond copper-aluminum nitride composite functional substrate material, single alumina ceramic material, and single aluminum nitride ceramic material at the same size. The room temperature thermal conductivity is 307.96 W / m·K, 30 W / m·K, and 200 W / m·K, respectively. Compared to single alumina and aluminum nitride ceramics, the diamond copper embedded structure significantly improves the thermal conductivity of the composite functional substrate, achieving a thermal conductivity ≥300 W / m·K at room temperature. At 200℃, the thermal conductivity of the diamond copper-aluminum nitride composite functional substrate material provided in this embodiment is 255.26 W / m·K. Figure 10 The overall temperature distribution under operating conditions of 200℃ and a heat flux density of 80W / cm² is presented.

[0083] Table 2 compares the thermal conductivity of diamond copper-aluminum nitride composite functional substrate materials, single alumina ceramic materials, and single aluminum nitride ceramics of the same size in Example 2.

[0084] Mechanical properties: Figure 11 The simulation results show that the maximum shear stress at the diamond-copper interface under 200℃ conditions is about 36MPa, which is much lower than the AlN / diamond-copper interface shear stress threshold (≤100MPa), effectively avoiding the interface peeling problem at high temperature.

[0085] (5) Conclusion The diamond copper-aluminum nitride composite functional substrate with this parameter combination (H=635μm, W=200μm, h=200μm, S=150μm) meets the requirements of room temperature thermal conductivity ≥300W / m·K, interface shear strength ≤100MPa at 100℃, and evaluation function F≥0, making it suitable for the application requirements of 28GHz high-frequency thin-film antennas.

[0086] The above description is merely a specific embodiment of the present invention and does not constitute any limitation on the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multiphysics design method for a high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate, characterized in that, include: Design a high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate based on target requirements. The substrate includes an aluminum nitride plate, and multiple square or rectangular grooves are arrayed on the surface of the aluminum nitride plate; each groove is filled with diamond copper composite material. An active metal brazing layer is provided between the diamond copper composite material and the inner wall of the tank. Each tank has rounded corners at its bottom four corners, with a radius R of 20-30 μm. The inner wall of each tank is roughened, with a surface roughness Ra = 0.8-1.2 μm; A parametric model of a rectangular slotted diamond copper-aluminum nitride composite functional substrate was constructed using finite element analysis software, and core parameters were defined. The mesh is divided using local densification, where boundary layers are set to refine each tank area and the active metal brazing layer area within each tank. Thermal simulation of the substrate: Input the thermal performance parameters of aluminum nitride, copper diamond and solder layer, apply surface heat flux density to simulate chip heating, set the ambient temperature boundary at the bottom, and output the overall thermal conductivity; Mechanical simulation of the substrate: The thermal simulation temperature field is imported into the structural mechanics module as a load to calculate thermal stress and deformation displacement, while monitoring the interface shear stress. The evaluation function is defined based on the interfacial shear stress at the highest operating temperature and the thermal conductivity at room temperature; A genetic algorithm is used to optimize the variables in the evaluation function, select the core parameter combination that meets the target requirements, and output the optimal parameter report of the substrate.

2. The multiphysics design method for a high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 1, characterized in that, The acceptable threshold for thermal conductivity to meet the target requirements is a thermal conductivity of ≥300W / m·K at room temperature; the acceptable threshold for interfacial shear stress is an interfacial shear stress of <100MPa at the highest operating temperature.

3. The multiphysics design method for high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 1, characterized in that, The core parameters include the base thickness, tank side length, tank spacing, tank depth, inner corner radius of the tank, and brazing layer thickness.

4. The multiphysics design method for high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 1, characterized in that, The evaluation function is: F=ω1×(σ_max)+ω2×(T_junction) In the formula, σ_max is the interfacial shear stress score at the highest operating temperature, where 30MPa is 10 points, decreasing by 7MPa / point; the weight ω1≥0.6; T_junction is the score for thermal conductivity at room temperature, where 500 W / m·K is 10 points, decreasing by 20 W / m·K / point; the weight ω2 = 0.2-0.

4.

5. The multiphysics design method for a high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 4, characterized in that, During the optimization of the variables in the evaluation function, the qualified thresholds are set as F≥0, σ_max≥0, and T_junction≥0.

6. The multiphysics design method for high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 1, characterized in that, The aluminum nitride plate has a dielectric constant εr = 7-10, a thermal conductivity of 100-200 W / m·K, and a coefficient of thermal expansion of 2.5-5 × 10⁻⁶. -6 / K.

7. The multiphysics design method for high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 1, characterized in that, The diamond-copper composite material has a thermal conductivity of 400-700 W / m·K and a coefficient of thermal expansion of 6.5-9 × 10⁻⁶. -6 / K; The diamond-copper composite material contains 35-45% diamond by volume and the diamond particle size is 100-300μm.

8. The multiphysics design method for high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 1, characterized in that, The brazing filler metal used to prepare the active metal brazing layer is Ag72-Cu28-Ti0.5; the thickness of the active metal brazing layer is 5-10 μm, the interfacial thermal resistance is ≤15 m²·K / W, and the interfacial shear strength is ≥100 MPa.

9. The multiphysics design method for a high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate according to claim 1, characterized in that, When using a genetic algorithm to optimize the variables in the evaluation function, the population size should be ≥50 and the number of iterations ≥30.

10. A high-temperature resistant, low-dielectric rectangular slot diamond copper-aluminum nitride composite functional substrate designed according to any one of claims 1 to 9.

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