Metallized high-thermal-conductivity insulating metal substrate and preparation method thereof

Abstract

The invention provides a metalized high-thermal-conductivity insulating metal substrate and a preparation method thereof, and the method comprises the steps: firstly preparing a metal substrate with a heat dissipation structure, then depositing a gradient high-thermal-conductivity ceramic insulating layer on the metal substrate, then sequentially depositing and thickening an electrode layer on the surface of the insulating layer, and finally carrying out the patterning of the electrode layer. And the metalized high-thermal-conductivity insulating metal substrate is obtained. A gradient high-thermal-conductivity ceramic insulating layer is prepared through a gradient deposition technology, and a heterogeneous interface of a'metal substrate-insulating layer-metal electrode 'sandwich structure in a traditional metallized insulating metal substrate adopting an organic-ceramic composite filler insulating layer is eliminated. A metal substrate with a heat dissipation structure and an insulating layer for realizing electrical insulation of an electronic element are integrated in situ, so that integration of an electrical function and the heat dissipation structure of a system level is realized, and the heat conduction and heat dissipation capability of the substrate is greatly improved. Meanwhile, the gradient insulating layer can relieve the problem that thermal expansion coefficients between metal and ceramic are not matched, and the reliability of the substrate is effectively enhanced.

Description

A metallized high thermal conductivity insulating metal substrate and its preparation method Technical Field

[0001] This invention belongs to the field of thermoelectric device technology, specifically relating to a metallized high thermal conductivity insulating metal substrate and its preparation method. Background Technology

[0002] With breakthroughs in 5G communication, data terminals, and artificial intelligence, the heat dissipation problem of electronic devices (such as power semiconductors, SoCs, and LEDs) has become increasingly severe in the current era of high integration and soaring power density, becoming a key bottleneck restricting device performance, reliability, and lifespan. Insulating substrates are crucial carriers for supporting and connecting electronic devices. Improving the thermal conductivity of insulating substrates can directly optimize the heat conduction path from the heat source to the external heat sink, which is the core and cornerstone for solving the heat dissipation problem of modern high-performance electronic devices.

[0003] Metallized insulating metal substrates (MIMS) consist of a metal substrate, an insulating layer, and an electrode layer, exhibiting excellent thermal conductivity and mechanical strength. Their core structure is a sandwich structure of "metal substrate-insulating layer-circuit layer." By utilizing a highly thermally conductive metal as the substrate, heat is rapidly conducted, while a thin, highly insulating, and highly thermally conductive dielectric layer ensures electrical insulation. Currently, MIMS are primarily fabricated by coating an insulating layer (such as epoxy resin or ceramic-filled polymer) and a copper foil circuit layer onto the surface of a metal substrate (usually aluminum or copper). However, during the manufacturing process of MIMS, "thermal resistance points" at the interface between the metal substrate and the insulating layer, caused by impurities such as air bubbles or uneven thermally conductive fillers, are difficult to completely avoid. These points severely hinder heat transfer, significantly reducing overall heat dissipation efficiency. Furthermore, due to the mismatch in thermal conductivity (CTE) between the metal and insulating materials, repeated thermal cycling during electronic device operation generates significant mechanical stress at the interface, leading to problems such as substrate warping, delamination, peeling, or cracking. Therefore, there is an urgent need to develop metallized high thermal conductivity insulating metal substrates that combine electrical insulation, efficient heat dissipation, and high reliability, and to develop new integrated manufacturing technologies compatible with them. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this invention provides a metallized high thermal conductivity insulating metal substrate and its fabrication method. This invention utilizes dynamic in-situ deposition technology to prepare a gradient insulating layer on the surface of the metal substrate, achieving integration of heat dissipation structure and electrical function. This reduces the additional thermal resistance between the heat sink and the substrate, and between the substrate and the insulating layer, significantly improving the substrate's thermal conductivity and heat dissipation capacity. Simultaneously, the gradient core insulating layer alleviates the CET mismatch problem between the metal and ceramic, effectively enhancing the substrate's reliability.

[0005] The technical solution adopted in this invention is as follows: a method for preparing a metallized high thermal conductivity insulating metal substrate, comprising the following steps: (1) processing a metal substrate with a heat dissipation structure; (2) depositing a gradient high thermal conductivity ceramic insulating layer on the metal substrate; (3) depositing a metal electrode layer on the surface of the insulating layer; (4) depositing a thickened metal electrode layer on the surface of the metal electrode layer; (5) patterning the metal electrode layer to obtain the metallized high thermal conductivity insulating metal substrate.

[0006] In step (1), the metal substrate with heat dissipation structure is: having microchannels inside as heat dissipation structure, or having heat dissipation fins on the surface as heat dissipation structure; the heat dissipation structure is made by any one or more of the following methods: casting, mechanical cutting, laser engraving, and chemical etching.

[0007] The metal substrate is any one or more of Al, Cu, stainless steel, Ti, and Ni substrates; in step (2), the surface treatment process specifically involves: performing surface planarization on the surface of the metal substrate, with a surface roughness Ra ranging from 10 to 100 nm, preferably below 50 nm; then cleaning the planarized metal substrate to remove oil or impurity particles, resulting in a smooth and clean metal substrate. The surface treatment process used is beneficial for significantly reducing the surface roughness of the metal substrate, enabling better insulation and breakdown resistance with a thinner insulating layer.

[0008] In step (2), the gradient high thermal conductivity ceramic insulating layer is prepared by a gradient deposition method in which the insulating layer gradually changes its thickness as it grows; the insulating layer includes a metallic material composition and a ceramic material composition; the metallic material composition content of the insulating layer gradually decreases from 100% to 0% with increasing thickness, while the ceramic material composition content gradually increases from 0% to 100% with increasing thickness, thus preparing the gradient high thermal conductivity ceramic insulating layer; for a metal Al substrate, preferably, the gradient high thermal conductivity ceramic insulating layer is a gradient Al-Al2O3 insulating layer; the gradient high thermal conductivity ceramic insulating layer The specific preparation process is as follows: a. A metal substrate with a heat dissipation structure is placed in a deposition apparatus with the surface-treated side facing outwards, and a metal material with the same element as the metal substrate is deposited on the smooth and clean surface of the metal substrate; b. After step a, a metal material with the same element as the metal substrate and an insulating ceramic material corresponding to the metal element are deposited simultaneously, and the growth rate of the metal material is gradually reduced while the growth rate of the insulating ceramic material is increased during the growth process; c. After step b, the growth rate of the metal material is reduced to 0, and the insulating ceramic material is deposited again until the required thickness is reached and then the growth is terminated.

[0009] Preferably, the specific preparation process of the gradient high thermal conductivity ceramic insulating layer is as follows: a. A metal substrate with a heat dissipation structure is placed in a magnetron sputtering cavity with the surface-treated side facing outwards. Under an Ar gas flow rate of 10-20 sccm, a cavity gas pressure of 1-1.5 Pa, and a substrate temperature of 200-400℃, DC sputtering of metal Al is performed for 20-40 minutes, with a DC sputtering power of 50-70 W; b. After step a, simultaneous DC sputtering of metal Al and radio frequency sputtering of ceramic Al2O3 is performed for a total of 10-20 minutes, with a DC sputtering power of 50-70 W and a radio frequency sputtering power of 150-200 W; c. After step b, simultaneous DC sputtering of metal Al and radio frequency sputtering of ceramic Al2O3 is performed for a total of 20-30 minutes; the DC sputtering power is... The power is 20~40W, and the power of the radio frequency sputtering is 150~200W; d. After step c, simultaneously sputter metal Al and radio frequency sputter ceramic Al2O3 for a total of 30~40min; the power of the DC sputtering is 10~20W, and the power of the radio frequency sputtering is 150~200W; e. After step d, simultaneously sputter metal Al and radio frequency sputter ceramic Al2O3 for a total of 50~60min; the power of the DC sputtering is 5~10W, and the power of the radio frequency sputtering is 150~200W; f. After step e, radio frequency sputter ceramic Al2O3 for a total of 180~300min, the power of the radio frequency sputtering is 150~200W. After sputtering is completed, hold at the temperature for 180~300min, and then cool down to room temperature at a cooling rate of 1~3℃ per minute.

[0010] The magnetron sputtering method employed can deposit high-performance insulating layers with adjustable film thicknesses from 1 μm to 10 μm. Furthermore, ceramic materials possess advantages such as high temperature resistance, corrosion resistance, breakdown resistance, and high thermal conductivity, which are beneficial for improving the thermal conductivity and reliability of the substrate. The magnetron sputtering method also enables the deposition of gradient insulating layers, facilitating a gradual transition and integration between the insulating layer and the metal substrate, eliminating the interface between the metal substrate and the ceramic insulating layer, and further enhancing the thermal conductivity and reliability of the substrate.

[0011] The total thickness of the insulating layer is 1~30μm, which can be adjusted according to the insulation performance requirements. The preferred thickness is 3μm when the withstand voltage is 100V.

[0012] After depositing and thickening the metal electrode layer using one or more of the following methods—magnetron sputtering, molecular beam epitaxy, electron beam evaporation, chemical deposition, and electrochemical deposition—the total thickness of the electrode layer is 10-300 μm, preferably 40 μm. The metal electrode layer is one or a combination of Au, Ag, Cu, Fe, Al, Ni, Sn, and Ti electrodes. Preferably, the electrode layer is a Ti-Cu electrode layer, and a Cu electrode layer is further deposited and thickened on the surface of the Ti-Cu electrode layer.

[0013] In step (3), the specific preparation steps of the Ti-Cu electrode layer are as follows: A. Under the conditions of Ar gas flow rate of 10~20 sccm, cavity gas pressure of 1~1.5 Pa, substrate temperature is set to 200~400℃, and metal Ti is sputtered by DC for 10~30 min, with a DC sputtering power of 50~100W; B. After step A, metal Ti and Cu are sputtered simultaneously by DC sputtering; the sputtering power of metal Ti is 50~100W, and the sputtering time of metal Ti is 10~30 min; the sputtering power of metal Cu is 50~100W, and the sputtering time of metal Cu is 10~30 min; C. After step B, metal Cu is sputtered by DC for 120~300 min, with a DC sputtering power of 50~100W. After sputtering is completed, the sample is taken out when the temperature drops below room temperature.

[0014] Preferably, the electrode layer is a Ti-Cu electrode layer, and a thickened Cu electrode layer is further deposited on the surface of the Ti-Cu electrode layer. After depositing the thickened Cu electrode layer, the total thickness of the electrode layer is 10-300 μm, preferably 40 μm.

[0015] The specific preparation steps of the thickened Cu electrode layer are as follows: A metal substrate with an insulating layer and a Ti-Cu electrode layer is clamped in a Pt electrode fixture and then immersed in a copper plating solution. A pure copper sheet of the same size as the substrate is used as the sacrificial electrode for electroplating, and an A·dm² solution is applied. -2 Deposition was performed at a DC current density for 10–30 min, followed by deposition at 0.1–1 A·dm³. -2 The substrate is deposited at a DC current density for 10-30 minutes. After the electroplating is completed, the substrate is removed from the copper plating solution and then immersed in deionized water, ethanol, and acetone in sequence for ultrasonic cleaning. Finally, it is dried with nitrogen to obtain a thickened Cu electrode layer.

[0016] The in-situ integration of the metal substrate with the insulating layer and electrode layer helps to eliminate redundant interfaces between the metallized insulating metal substrate and the heat sink, greatly improving the heat conduction and heat dissipation capabilities of the substrate.

[0017] In step (5), the metal electrode layer is patterned using one or more of the following techniques: mechanical cutting, laser engraving, chemical etching, and photolithography. Preferably, the pattern line width is not less than 10 μm.

[0018] Preferably, in step (5), laser ablation is used for patterning, which is beneficial to improve processing accuracy and efficiency and reduce processing costs.

[0019] The specific operation is as follows: An insulating substrate with a deposited thickened electrode layer is placed under a femtosecond laser with a pulse frequency of 100 kHz, a pulse width of 290 fs, a center wavelength of 243 nm, and a beam waist radius of 7.5 μm. The laser source power is set between 0.980 and 1.852 W, and the sample is subjected to 30 to 60 pulses at a speed of 100 to 300 mm / s. -1 Line scan.

[0020] The method yields a metallized, highly thermally conductive, insulating metal substrate.

[0021] This invention offers the following advantages: It provides a method for preparing a metallized high thermal conductivity insulating metal substrate. The method involves first preparing a metal substrate with a heat dissipation structure, then depositing a gradient high thermal conductivity ceramic insulating layer on the metal substrate. Next, metal electrode layers are sequentially deposited and thickened on the surface of the insulating layer. Finally, the electrode layers are patterned to obtain the metallized high thermal conductivity insulating metal substrate. This application utilizes a gradient deposition technique to prepare the gradient high thermal conductivity ceramic insulating layer, eliminating the heterogeneous interface of the "metal substrate-insulating layer-metal electrode" sandwich structure found in traditional metallized insulating metal substrates using organic-ceramic composite filler insulating layers. This method integrates the metal substrate with the heat dissipation structure with the insulating layer that provides electrical insulation for electronic components in situ, achieving system-level integration of electrical functions and heat dissipation structure. This reduces the additional thermal resistance between the heat sink and the substrate, and between the substrate and the insulating layer, significantly improving the substrate's thermal conductivity and heat dissipation capabilities. Simultaneously, the gradient core insulating layer alleviates the CET mismatch problem between the metal and ceramic, effectively enhancing the substrate's reliability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 shows a process flow diagram of the metallized high thermal conductivity insulating metal substrate described in Embodiment 1 of the present invention; Figure 2 shows SEM images and EDS elemental line scans of the gradient insulating layer of the metallized high thermal conductivity insulating metal substrate described in Embodiment 1 of the present invention; wherein, (a) is an SEM image of the gradient insulating layer, and (b) is an EDS elemental distribution scan of the gradient insulating layer from the metal substrate to the insulating layer and then to the electrode layer; Figure 3 shows a comparison of nano-scratch tests of the metallized insulating metal substrate with gradient insulating layer and ordinary insulating layer described in Embodiment 1 of the present invention; Figure 4 shows an image comparison of the metallized insulating metal substrate with gradient insulating layer and ordinary insulating layer described in Embodiment 1 of the present invention after 500 thermal shocks from -20℃ to 80℃; Figure 5 shows the metallized high thermal conductivity insulating metal substrate described in Embodiment 1 of the present invention. A comparison of the thermal conductivity tests of the substrate, the conventional metallized insulating metal substrate, and the conventional metallized Al2O3 ceramic substrate is shown in Figure 6. Figure 6 shows the insulation performance test of the metallized high thermal conductivity insulating metal substrate described in Example 1 of the present invention. Among them, (a) is the surface roughness of the metal substrate after treatment with sandpaper of different mesh sizes, (b) is the resistance when the insulation layer thickness is 3μm, (c) is the breakdown voltage when the insulation layer thickness is 3μm, and (d) is the withstand voltage test of 100V for 100min when the insulation layer thickness is 3μm. Figure 7 shows the magnified image and EDS element surface scan of the electrode pattern of the substrate described in Example 1 of the present invention. Among them, (a)-(c) are the top view and cross-sectional view of the electrode pattern at different magnifications, and (d) is the EDS surface scan element distribution of the electrode pattern. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] Unless otherwise specified, all reagents involved in the specific embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0026] Example 1: This example provides a method for preparing a metallized high thermal conductivity insulating metal substrate. The process flow diagram is shown in Figure 1. The specific steps include:

[0027] (1) Processing a metal substrate with a heat dissipation structure: Take a metal Al substrate and use laser drilling to process microchannels inside the substrate to form a metal substrate with a heat dissipation structure; (2) Depositing a gradient Al-Al2O3 insulating layer on the metal substrate: Perform surface treatment on the metal substrate with a heat dissipation structure obtained in step (1), and deposit a gradient Al-Al2O3 insulating layer on the surface of the surface-treated metal substrate; the total thickness of the insulating layer is 3±0.2μm; the surface treatment process is as follows: using a polishing machine to sequentially apply polishing with mesh sizes of 400 mesh, 800 mesh, 1500 mesh, 2500 mesh, ... The substrate surface was polished with 5000-grit and 10000-grit sandpaper to achieve a surface roughness Ra of less than 50 nm. Then, the substrate was sequentially immersed in detergent-water, deionized water, ethanol, and acetone for ultrasonic cleaning. After drying with nitrogen, the substrate was cleaned using plasma technology to obtain the surface-treated metal substrate. The specific preparation process of the gradient Al-Al2O3 insulating layer is as follows: a. The metal substrate with a heat dissipation structure is placed in the magnetron sputtering cavity with the surface-treated side facing outwards, under Ar gas flow rate of 15 sccm and cavity pressure of 1.2 Pa. a. The substrate temperature is set to 400℃, and DC sputtering of metal Al is performed for 30 minutes at a power of 60W; b. After step a, simultaneous DC sputtering of metal Al and RF sputtering of ceramic Al2O3 are performed for a total of 10 minutes, with DC sputtering power of 60W and RF sputtering power of 200W; c. After step b, simultaneous DC sputtering of metal Al and RF sputtering of ceramic Al2O3 are performed for a total of 20 minutes, with DC sputtering power of 30W and RF sputtering power of 200W; d. After step c, simultaneous DC sputtering of metal Al... e. After step d, simultaneously sputter metal Al and radio frequency sputtered ceramic Al2O3 for a total of 50 minutes; the DC sputtering power is 15W and the radio frequency sputtering power is 200W; f. After step e, simultaneously sputter metal Al and radio frequency sputtered ceramic Al2O3 for a total of 50 minutes; the DC sputtering power is 7W and the radio frequency sputtering power is 200W; g. After step e, use radio frequency sputtered ceramic Al2O3 for a total of 200 minutes, the radio frequency sputtering power is 200W, after sputtering is completed, hold at temperature for 200 minutes, and then cool down to 200℃ at a cooling rate of 1.5℃ per minute.

[0028] (3) Depositing a Ti-Cu electrode layer on the surface of the insulating layer. A Ti-Cu electrode layer is deposited on the surface of the gradient Al-Al2O3 insulating layer. The thickness of the Ti-Cu electrode layer is 3±0.2μm. The specific preparation steps are as follows: A. Under the conditions of Ar gas flow rate of 15sccm, cavity gas pressure of 1.2Pa, substrate temperature is set to 400℃, and metal Ti is sputtered by DC for 15min. The power of DC sputtering is 100W. B. After step A, metal Ti and Cu are sputtered simultaneously by DC sputtering. The power of sputtering metal Ti is 50W and the sputtering time of metal Ti is 15min. The power of sputtering metal Cu is 50W and the sputtering time of metal Cu is 15min. C. After step B, metal Cu is sputtered by DC for 150min. The power of DC sputtering is 100W. After sputtering is completed, the sample is taken out after the temperature drops to room temperature.

[0029] (4) Depositing a thickened electrode layer: A thickened Cu electrode layer is further deposited on the surface of the Ti-Cu electrode layer; the specific preparation steps of the thickened Cu electrode layer are as follows: the metal substrate with the insulating layer and the Ti-Cu electrode layer is clamped with a Pt electrode clamp and then immersed in a copper plating solution. A pure copper sheet of the same size as the substrate is used as the sacrificial electrode for electroplating, and a plating strength of 0.1 A·dm -2 Deposition was performed at a DC current density for 10 minutes, followed by deposition at 0.5 A·dm³. -2 The substrate was deposited at a DC current density for 20 minutes. After the electroplating thickening was completed, the substrate was removed from the copper plating solution. Then, the substrate was immersed in deionized water, ethanol, and acetone in sequence for ultrasonic cleaning. Finally, it was dried with nitrogen gas to obtain the thickened Cu electrode layer.

[0030] After depositing the thickened Cu electrode layer, the total thickness of the metal electrode layer is 50±5μm; (5) Electrode layer patterning: The electrode layer is patterned by laser ablation to obtain the metallized high thermal conductivity insulating metal substrate; The specific operation of the patterning is as follows: The insulating substrate with the deposited thickened electrode layer is placed under a femtosecond laser with a pulse frequency of 100kHz, a pulse width of 290fs, a center wavelength of 243nm, a beam waist radius of 7.5μm, and the laser source power is set between 0.980W and 1.852W. The sample is subjected to 50 times at a speed of 200mm / s. -1 Line scan.

[0031] Example 2: This example provides a method for preparing a metallized high thermal conductivity insulating metal substrate. The process flow diagram is shown in Figure 1. The specific steps include:

[0032] (1) Processing a metal substrate with a heat dissipation structure: Take a metal Al substrate and cast it to form a metal substrate with heat dissipation fins; (2) Depositing a gradient Al-AlN insulating layer on the metal substrate: Perform surface treatment on the metal substrate with a heat dissipation structure obtained in step (1), and deposit a gradient Al-AlN insulating layer on the surface of the surface-treated metal substrate; The total thickness of the insulating layer is 3±0.2μm; The surface treatment process is as follows: Polish the substrate with sandpaper of 400 mesh, 800 mesh, 1500 mesh, 2500 mesh, 5000 mesh and 10000 mesh in sequence using a polishing machine. The surface of the substrate is ground to achieve a surface roughness Ra of less than 50 nm. Then, the substrate is sequentially immersed in detergent-water, deionized water, ethanol, and acetone for ultrasonic cleaning. After drying with nitrogen, the substrate is cleaned using plasma technology to obtain a surface-treated metal substrate. The specific preparation process of the gradient Al-AlN insulating layer is as follows: a. The metal substrate with a heat dissipation structure is placed in the magnetron sputtering cavity with the surface-treated side facing outwards. At an Ar gas flow rate of 15 sccm, a cavity pressure of 1.2 Pa, and a substrate temperature of 400℃, DC sputtering is used. a. After step a, reactive sputtering of Al metal for 10 minutes at a DC power of 100W; b. After step a, reactive sputtering of Al metal for 15 minutes at a mixed atmosphere of 12 sccm Ar gas flow rate, 3 sccm N2 gas flow rate, and a chamber pressure of 1.2 Pa; c. After step b, reactive sputtering of Al metal for 30 minutes at a mixed atmosphere of 9 sccm Ar gas flow rate, 6 sccm N2 gas flow rate, and a chamber pressure of 1.2 Pa; d. Step c. After that, under a mixed atmosphere of Ar gas flow rate of 6 sccm, N2 gas flow rate of 9 sccm, and cavity gas pressure of 1.2 Pa, DC reactive sputtering of metal Al was performed for a total of 60 min, and the DC reactive sputtering power was 100 W; e. After step d, under a mixed atmosphere of Ar gas flow rate of 3 sccm, N2 gas flow rate of 12 sccm, and cavity gas pressure of 1.2 Pa, DC reactive sputtering of metal Al was performed for a total of 120 min, and the DC reactive sputtering power was 100 W. After sputtering, the metal was held at that temperature for 200 min, and then cooled to room temperature at a cooling rate of 1.5 °C per minute.

[0033] (3) Depositing and thickening the Ti-Cu electrode layer on the surface of the insulating layer. The Ti-Cu electrode layer is deposited on the surface of the gradient Al-AlN insulating layer. The thickness of the Ti-Cu electrode layer is 3±0.2μm. The specific preparation steps are as follows: A. Under the conditions of Ar gas flow rate of 15sccm, cavity gas pressure of 1.2Pa, substrate temperature is set to 400℃, and metal Ti is sputtered by DC for 15min. The power of DC sputtering is 100W. B. After step A, metal Ti and Cu are sputtered simultaneously by DC sputtering. The power of sputtering metal Ti is 50W and the sputtering time of metal Ti is 15min. The power of sputtering metal Cu is 50W and the sputtering time of metal Cu is 15min. C. After step B, metal Cu is sputtered by DC for 600min. The power of DC sputtering is 100W. After sputtering is completed, the sample is taken out after the temperature drops to room temperature.

[0034] After depositing the thickened Cu electrode layer, the total thickness of the metal electrode layer is 30±5μm; (4) Electrode layer patterning: The electrode layer is patterned using photolithography, thus obtaining the metallized high thermal conductivity insulating metal substrate; The specific operation of the patterning is as follows: S1813 photoresist is spin-coated on the surface of the metal electrode layer, and the pre-designed electrode layer pattern is exposed by ultraviolet light, with an exposure energy of 150mJ / cm 2 After development and fixing, the sample was wet-etched using a 2.5wt% FeCl3 solution to pattern the electrode layer. Finally, acetone was used to remove the residual photoresist on the surface.

[0035] Example 3: This example provides a method for preparing a metallized high thermal conductivity insulating metal substrate. The difference from the example is that the operation method for processing the heat dissipation structure in step (1) is different. Specifically, heat dissipation fins are processed on the surface of the substrate by mechanical cutting to form a metal substrate with a heat dissipation structure.

[0036] In step (2), after the surface treatment, the surface roughness Ra of the metal substrate is less than 50 nm.

[0037] As an alternative implementation, the gradient insulating layer of the present invention can be adjusted according to the type of metal substrate. For example, for Al substrates, Al2O3 or AlN can be used as the insulating layer material; for Cu substrates, CuO or Cu2O can be used as the insulating layer; and for stainless steel substrates, Fe2O3 or Fe3O4 can be used as the insulating layer.

[0038] As an alternative implementation, the metal electrode layer of the present invention may be one or a combination of several of the following: Au electrode, Ag electrode, Cu electrode, Fe electrode, Al electrode, Ni electrode, Sn electrode, and Ti electrode.

[0039] Example 4: Performance testing of the metallized high thermal conductivity insulating metal substrate obtained in Example 1.

[0040] This invention utilizes a gradient deposition technique to fabricate a gradient insulating layer for metallized high thermal conductivity insulating metal substrates. This eliminates the intermediate interface of the "metal substrate-insulating layer-metal electrode" sandwich structure in traditional metallized insulating metal substrates, allowing for in-situ integration of the metal substrate with a heat dissipation structure and the insulating layer that performs electrical functions, achieving system-level integration of electrical functions and heat dissipation structure. Figure 2 shows the SEM image and EDS elemental scan of the gradient insulating layer of the metallized high thermal conductivity insulating metal substrate described in Embodiment 1 of this invention; where (a) is the SEM image of the gradient insulating layer, showing no heterogeneous material interface between the metal substrate and the insulating layer, and between the insulating layer and the electrode layer; (b) is the EDS elemental distribution scan of the gradient insulating layer from the metal substrate to the insulating layer and then to the electrode layer, showing a smooth elemental transition at the junction of heterogeneous materials.

[0041] The gradient insulating layer described in this invention can effectively alleviate and overcome the CET mismatch problem between the metal and the insulating layer, significantly improving the bonding strength between the metal-ceramic heteromaterials of the substrate. Figure 3 shows the nano-scratch test of the metallized insulating metal substrate using the gradient insulating layer and the ordinary insulating layer of Example 1 of this invention. In a scratch length of 200 μm, the load gradually increases from 0 to 100 mN. The gradient insulating layer bonds well with the substrate, while the ordinary insulating layer peels off. Figure 4 shows images of the metallized insulating metal substrate using the gradient insulating layer and the ordinary insulating layer after 500 cycles of thermal shock from -20℃ to 80℃. The gradient insulating layer bonds well with the substrate, while the ordinary insulating layer peels off.

[0042] In Embodiment 1 of this invention, the gradient insulating layer eliminates heterogeneous interfaces, avoiding additional contact thermal resistance and effectively improving the thermal conductivity and heat dissipation capacity of the substrate. Figure 5 compares the thermal conductivity of the metallized high thermal conductivity insulating metal substrate described in Embodiment 1 of this invention with that of a conventional metallized insulating metal substrate and a conventional metallized Al2O3 ceramic substrate. The red line represents the "metallized high thermal conductivity insulating metal substrate," the green line represents the "conventional metallized insulating metal substrate," and the blue line represents the "conventional metallized Al2O3 ceramic substrate." Thus, the substrate using the gradient insulating layer exhibits superior thermal conductivity and heat dissipation capacity, reaches thermal stability more quickly, and in the stable state, the temperature of the substrate surface is closest to the temperature of the underlying hot platen.

[0043] This invention employs a surface polishing treatment on the metal substrate that is completely different from the surface roughening treatment of traditional metallized insulating metal substrates, which can significantly improve the actual insulation performance of the insulating layer of the same thickness on the metallized insulating metal substrate. As shown in Figure 6, (a) is the surface roughness of the metal substrate after treatment with sandpaper of different grits, (b) is the resistance when the corresponding insulating layer thickness is 3μm, (c) is the breakdown voltage when the corresponding insulating layer thickness is 3μm, and (d) is the withstand voltage test of 100V for 100min when the corresponding insulating layer thickness is 3μm.

[0044] The laser ablation process used in this invention is applied in the field of metallized insulating metal substrate preparation. It can achieve high-precision patterning that is impossible with traditional copper cladding processes. Compared with traditional photolithography processes, it is simpler and cheaper, and can also achieve micron-level processing that targets only the electrode layer without damaging the insulating layer. As shown in Figure 7, (ac) are top views and cross-sectional views of electrode patterns at different magnifications, and (d) is the EDS surface scan element distribution of the electrode pattern.

[0045] This invention provides a method for fabricating a metallized high thermal conductivity insulating metal substrate. The method involves first fabricating a metal substrate with a heat dissipation structure, then depositing a gradient high thermal conductivity ceramic insulating layer on the metal substrate, followed by sequentially depositing and thickening a Ti-Cu electrode layer on the surface of the insulating layer, and finally patterning the electrode layer to obtain the metallized high thermal conductivity insulating metal substrate. This application utilizes a gradient deposition technique to fabricate the gradient high thermal conductivity ceramic insulating layer, eliminating the heterogeneous interface of the "metal substrate-insulating layer-metal electrode" sandwich structure found in traditional metallized insulating metal substrates using organic-ceramic composite filler insulating layers. It integrates the metal substrate with the heat dissipation structure in situ with the insulating layer that provides electrical insulation for electronic components, and integrates the metal substrate with the heat dissipation structure in situ with the insulating layer that provides electrical functions. This achieves system-level integration of electrical functions and heat dissipation structure, reducing additional thermal resistance between the heat sink and the substrate, and between the substrate and the insulating layer, significantly improving the thermal conductivity and heat dissipation capacity of the substrate. Simultaneously, the gradient core insulating layer alleviates the problem of mismatched thermal expansion coefficients between the metal and ceramic, effectively enhancing the reliability of the substrate.

Claims

1. A method for preparing a metallized high thermal conductivity insulating metal substrate, characterized in that the steps include... include: (1) Processing a metal substrate with a heat dissipation structure: Take a metal substrate and process it into a metal substrate with a heat dissipation structure; (2) Deposit a gradient high thermal conductivity ceramic insulating layer on the metal substrate. The metal substrate with heat dissipation structure obtained in step (1) is surface treated, and a gradient high thermal conductivity ceramic insulating layer is deposited on the smooth and clean surface of the metal substrate after surface treatment. (3) Deposit a metal electrode layer on the surface of the insulating layer. A metal electrode layer is deposited on the surface of the gradient high thermal conductivity ceramic insulating layer. (4) Deposit a thickened metal electrode layer. A thickened metal electrode layer is further deposited on the surface of the metal electrode layer. (5) Pattern the metal electrode layer. The electrode layer is patterned to obtain the metallized high thermal conductivity insulating metal substrate.

2. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 1, characterized in that, In step (1), the metal substrate with heat dissipation structure is: having microchannels inside as heat dissipation structure, or having heat dissipation fins on the surface as heat dissipation structure; the heat dissipation structure is made by any one or more of the following methods: casting, mechanical cutting, laser engraving, and chemical etching.

3. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 1, characterized in that, The metal substrate is any one or more of metal Al substrate, metal Cu substrate, metal stainless steel substrate, metal Ti substrate, and metal Ni substrate; in step (2), the surface treatment process is as follows: the surface of the metal substrate is subjected to surface planarization treatment, the surface roughness Ra of the metal substrate is in the range of 10~100nm, preferably the roughness is less than 50nm; then the metal substrate after planarization treatment is cleaned to remove oil or impurity particles, so as to obtain a smooth and clean metal substrate.

4. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 1, characterized in that, In step (2), the gradient high thermal conductivity ceramic insulating layer is prepared by a gradient deposition method in which the composition of the insulating layer gradually changes as the insulating layer grows and thickens; the insulating layer includes a metal material component and a ceramic material component; the metal material component content of the insulating layer gradually decreases from 100% to 0% with the thickness, while the ceramic material component content gradually increases from 0% to 100% with the thickness; for a metal Al substrate, preferably, the gradient high thermal conductivity ceramic insulating layer is a gradient Al-Al2O3 insulating layer.

5. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 4, characterized in that, The specific preparation process of the gradient high thermal conductivity ceramic insulating layer is as follows: a. A metal substrate with a heat dissipation structure is placed in a deposition apparatus with the surface treated side facing outwards, and a metal material with the same elements as the metal substrate is deposited on the smooth and clean surface of the metal substrate. b. After step a, simultaneously deposit a metal material with the same element as the metal substrate and an insulating ceramic material corresponding to the metal element, and gradually reduce the growth rate of the metal material and increase the growth rate of the insulating ceramic material during the growth process. c. After step b, reduce the growth rate of the metal material to 0, continue to deposit the insulating ceramic material, and stop the growth after the required thickness is reached.

6. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 4 or 5, characterized in that, The total thickness of the insulating layer is 1~30μm; it is adjusted according to the insulation performance requirements, and the preferred thickness is 3μm when the withstand voltage is 100V.

7. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 1, characterized in that, After depositing and thickening the metal electrode layer using one or more of the following methods, namely magnetron sputtering, molecular beam epitaxy, electron beam evaporation, chemical deposition, and electrochemical deposition, the total thickness of the metal electrode layer is 10~300μm, preferably 40μm.

8. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 1, characterized in that, The metal electrode layer is one or a combination of several of Au, Ag, Cu, Fe, Al, Ni, Sn, and Ti electrodes. Preferably, the metal electrode layer is a Ti-Cu electrode layer, and a thickened Cu electrode layer is further deposited on the surface of the Ti-Cu electrode layer.

9. The method for preparing a metallized high thermal conductivity insulating metal substrate according to claim 1, characterized in that, In step (5), one or more of the following techniques are used to pattern the metal electrode layer: mechanical cutting, laser engraving, chemical etching, and photolithography.

10. A metallized high thermal conductivity insulating metal substrate prepared by the method according to any one of claims 1-9.

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