Ultrahigh-thermal-conductivity multilayer ceramic substrate structure and preparation method thereof

Abstract

The invention provides an ultrahigh-heat-conduction multilayer ceramic substrate structure and a preparation method thereof, which are applied to the technical field of semiconductors, and are characterized in that a double-sided aluminum-coated ceramic substrate and a single-sided aluminum-coated ceramic substrate are subjected to film pasting and exposure treatment through pattern transfer treatment, then a chip welding layer and a runner layer are etched on the double-sided aluminum-coated ceramic substrate through chemical etching, and finally the ultrahigh-heat-conduction multilayer ceramic substrate structure is obtained. A water supply layer and a runner layer are etched on a single-face aluminum-coated ceramic substrate to provide cooling water and gentle temperature gradient, the interior is designed to be arranged in an array grid mode, the heat dissipation contact area is increased, then a double-face aluminum-coated ceramic substrate and the single-face aluminum-coated ceramic substrate are welded through a friction stir welding method, and the multi-layer ceramic substrate is obtained. According to the method, the multilayer ceramic substrate is subjected to surface treatment, and finally, the edge of the multilayer ceramic substrate subjected to surface treatment is punched, so that a product obtained by the method has relatively high heat conductivity, the heat dissipation capability of a module is effectively improved, and the product has relatively high reliability.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly relates to a structure and preparation method of a multi-layer ceramic substrate with ultra-high thermal conductivity. Background Art

[0002] With the rapid development of the integration and high power of electronic devices, the high heat generated will inevitably lead to a decrease in the performance and reliability of the devices, causing the internal structure of the material to be damaged and deformed due to the mismatch of the thermal expansion coefficient. The existing electronic module designs usually adopt complex structures, are bulky, and have low thermal conductivity, and cannot meet the requirements of some special fields with strong reliability and high heat dissipation requirements, such as aerospace and small aircraft. Therefore, it is extremely urgent to design a power conversion device with a compact structure and high efficiency to meet the requirements in different power conversion scenarios.

[0003] Research shows that the failure rate of power modules increases with the increase of the operating temperature. On the basis of the normal operating temperature, for every 10 °C increase in temperature, the failure rate will approximately double. Therefore, the excellence of the cooling method of power modules has a great impact on their operating reliability and service life. At present, the packaging method of power modules is that the aluminum-clad or copper-clad ceramic substrate is welded to the bottom plate through solder. The surface thermal resistance is large, and due to the mismatch of the thermal expansion coefficient of the materials, stress accumulation occurs, and it is easy to separate the metallization layer at the substrate interface, resulting in reliability problems. Moreover, the bottom plates used are mostly high-density materials, and the overall packaging is too heavy and the cost is high, which cannot meet the requirements of some high-reliability and lightweight fields.

[0004] In order to overcome the defects of the prior art, we propose a structure and preparation method of a multi-layer ceramic substrate with ultra-high thermal conductivity to solve the above problems. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of this application is to improve the heat dissipation efficiency, make the thermal conductivity of the ceramic substrate better, smooth the temperature gradient, thereby reducing the problem of the sharp increase in surface roughness caused by thermal warping and stress accumulation brought by thermal cycling, and improving the thermal cycling reliability of power devices. Compared with the prior art, a structure and preparation method of a multi-layer ceramic substrate with ultra-high thermal conductivity are provided.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions.

[0007] A structure of a multi-layer ceramic substrate with ultra-high thermal conductivity includes a multi-layer ceramic substrate body. The multi-layer ceramic substrate body is composed of a double-sided aluminum-clad ceramic substrate and a single-sided aluminum-clad ceramic substrate. The pattern surface of the double-sided aluminum-clad ceramic substrate is the chip welding area. Both the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate include ceramic chips. The non-pattern surface of the double-sided aluminum-clad ceramic substrate is the flow channel layer, and the aluminum-clad layer of the single-sided aluminum-clad ceramic substrate is the water supply layer.

[0008] Further, the thickness of the ceramic chip is 3 - 7 mm, the aluminum thickness of the chip welding area is 0.1 - 0.4 mm, and the total thickness of the water supply layer and the flow channel layer is 2 - 4.5 mm.

[0009] A preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure includes the following steps:

[0010] Step 1, pattern transfer: perform pattern transfer on the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate through film design, film pasting, exposure, and development using a film.

[0011] Step 2, etching: etch the double-sided ceramic substrate and the single-sided ceramic substrate using an aluminum etchant.

[0012] Step 3, friction stir welding: take the double-sided ceramic substrate and the single-sided ceramic substrate obtained in Step 2 for friction stir welding to obtain a multi-layer ceramic substrate.

[0013] Step 4, surface treatment: take the multi-layer ceramic substrate obtained in Step 3 for surface treatment of the chip welding area to prepare a finished product.

[0014] Step 5, punching: take the multi-layer ceramic substrate obtained in Step 3 for mechanical punching.

[0015] Further, the types of ceramic chips of the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate in Step 1 include aluminum nitride ceramics, silicon nitride ceramics, and alumina ceramics.

[0016] Further, in Step 1, the film design of the non-graphic surface flow channel layer of the double-sided aluminum-clad ceramic substrate has a full-etching area, a non-etching area, and a process edge area. The film design of the aluminum-clad surface of the single-sided aluminum-clad ceramic substrate has a semi-etching area and a process edge area. The non-etching area is set as an array of squares, each square having a side length of 0.05 - 0.25 mm, and the distance between adjacent two squares is 0.05 - 0.2 mm. The full-etching area is completely etched, the process edge area is square, and the width of the process edge area is 3 - 5 m. The height difference between the semi-etching area and the process edge area is 1 / 2 of the thickness of the aluminum-clad layer of the single-sided aluminum-clad ceramic substrate.

[0017] Further, in Step 2, the aluminum etchant is a ferric chloride system, and the etching factor is 1 - 1.5.

[0018] Further, in the third step, friction stir welding is to weld the process edges of the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate. The rotation speed during friction stir welding is 800 - 1000 r / min, the welding speed is 50 - 75 mm / min, the elevation angle is 0°, the stirring head used for welding is a non-threaded conical stirring head, the length of the stirring pin is 2.5 - 4.5 mm, the length of the stirring pin matches the width of the process edge, and the length of the stirring pin is slightly less than the width of the process edge.

[0019] Further, in the fourth step, the surface treatment is electroless nickel immersion gold treatment. The nickel plating on the surface is electroless nickel plating in a sodium hypophosphite system. The components of the sodium hypophosphite electroless nickel plating solution are: 25 - 30 g / L of NiSO4·7H2O, 25 - 30 g / L of NaH2PO2·H2O, 15 - 20 g / L of CH3COONa, and 10 - 20 g / L of Na3C6H5O·2H2O. The components of the gold plating solution are: 0.5 - 2.5 g / L of KAu(CN)2, 45 - 55 g / L of C6H14N2O7, 8 - 12 g / L of NaH2PO2·H2O, 1 - 3 g / L of NiCl2, and 70 - 80 g / L of NH4Cl.

[0020] Further, in the fourth step, the nickel plating temperature is 78 - 85 °C, the nickel plating time is 20 - 25 min, the gold plating temperature is 83 - 88 °C, the pH value of the gold plating solution is 5 - 6, the gold plating time is 3 - 7 min. The stirring methods during nickel plating and gold plating are both air stirring. The thickness of the nickel layer after nickel plating is 4 - 6 μm, and the thickness of the gold layer after gold plating is 0.04 - 0.06 μm.

[0021] Further, in the fifth step, the aperture of the mechanical punching is 1.0 - 2.0 mm, and the punching position is at the center of the aluminum layer in the middle of the multi-layer ceramic substrate.

[0022] Compared with the prior art, the advantages of this application are as follows:

[0023] (1) The present invention provides a structure of a multi-layer ceramic substrate: chip welding area - ceramic chip - flow channel layer - water supply layer - ceramic chip. The interior of the multi-layer ceramic substrate is divided into a flow channel layer and a water supply layer. The flow channel layer is at one end close to the hot surface, and the flow channel layer is arranged in an array of squares. When the liquid flows, the contact area between water and the aluminum surface is increased, improving the heat dissipation efficiency; the water supply layer is at the end far from the hot surface, so the heat reaching the water supply layer is less, that is, the temperature rise of the fluid in the water supply layer is small, and at the same time, cooling water is continuously provided to the flow channel layer to smooth the temperature gradient. Therefore, the product of the present invention has excellent heat conduction effect, reduces problems such as a sharp increase in surface roughness caused by thermal cycling, and improves the thermal cycling reliability of power devices.

[0024] (2) By increasing the thickness of the ceramic and using an aluminum - clad ceramic substrate with a thicker ceramic chip, the stiffness of the multi - layer ceramic substrate is improved, meeting the stiffness requirements for use as a packaging base plate. In addition, during the welding process, the bonding of two aluminum - clad ceramic substrates is achieved through friction stir welding, avoiding defects such as cracks and bubbles generated during the aluminum - aluminum material welding process, and improving the reliability of the multi - layer ceramic substrate. The product prepared by the present invention has a great heat conduction effect, reducing the problems of thermal warping and stress accumulation caused by thermal cycling, and improving the thermal cycling reliability of power devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flowchart of the preparation method of this application;

[0026] Figure 2 is an exploded view of the finished product structure of this application;

[0027] Figure 3 is a cross - sectional view of the finished product of this application;

[0028] Figure 4 is a schematic diagram of the structure of a double - sided aluminum - clad ceramic substrate of this application;

[0029] Figure 5 is a schematic diagram of the structure of a single - sided aluminum - clad ceramic substrate of this application.

[0030] Explanation of the reference numerals in the figures:

[0031] 1. Chip welding area; 2. Ceramic chip; 3. Flow channel layer; 4. Water supply layer. SPECIFIC EMBODIMENTS

[0032] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

[0033] Embodiment 1:

[0034] The present invention provides a structure and preparation method of a super - high - thermal - conductivity multi - layer ceramic substrate. Please refer to Figures 1-5, including a multi-layer ceramic substrate body, which is composed of a double-sided aluminum-clad ceramic substrate and a single-sided aluminum-clad ceramic substrate. The graphic side of the double-sided aluminum-clad ceramic substrate is the chip welding area 1. Both the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate include ceramic chips 2. The non-graphic side of the double-sided aluminum-clad ceramic substrate is the flow channel layer 3, and the aluminum-clad layer of the single-sided aluminum-clad ceramic substrate is the water supply layer 4. Take double-sided aluminum nitride ceramic substrates and single-sided aluminum nitride ceramic substrates of the same size. Among them, the aluminum thickness of the chip welding area 1 on the graphic side of the double-sided aluminum nitride ceramic substrate is 0.2 mm, the aluminum thickness of the flow channel layer 3 on the non-graphic side is 1.5 mm, the aluminum nitride ceramic thickness of the double-sided aluminum nitride ceramic substrate is 3.5 mm, the aluminum thickness of the water supply layer 4 on the aluminum-clad side of the single-sided aluminum nitride ceramic substrate is 1.5 mm, and the aluminum nitride ceramic thickness of the single-sided aluminum nitride ceramic substrate is 3.5 mm.

[0035] A preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure includes the following steps:

[0036] Step 1, graphic transfer: Transfer the graphics of the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate through film design, film pasting, exposure, and development. Through film design, film pasting and exposure are carried out on the double-sided aluminum nitride ceramic substrate and the single-sided aluminum nitride ceramic substrate. Among them, in the film design of the non-graphic side of the double-sided aluminum nitride ceramic substrate, the side length of each array square in the non-etching area is 0.1 mm, the distance between adjacent two squares is 0.1 mm, and the width of the process edge area is 4 mm;

[0037] Step 2, etching: Etch the double-sided ceramic substrate and the single-sided ceramic substrate with an aluminum etching solution. Take the double-sided aluminum nitride ceramic substrate and the single-sided aluminum nitride ceramic substrate completed in Step 1 for etching. The etching solution system is a ferric chloride system, and the etching factor is 1;

[0038] Step 3, friction stir welding: Take the double-sided ceramic substrate and the single-sided ceramic substrate obtained in Step 2 for friction stir welding to obtain a multi-layer ceramic substrate. Take the double-sided aluminum nitride ceramic substrate and the single-sided aluminum nitride ceramic substrate that have completed etching in Step 2, and weld them at the process edges of the two substrates by friction stir welding. The rotation speed during friction stir welding is 1000 r / min, the welding speed is 70 mm / min, the elevation angle is 0°, the stirring head used for welding is a non-threaded conical stirring head, and the length of the stirring pin is 3.8 mm;

[0039] Step 4. Surface treatment: Take the multi-layer ceramic substrate obtained in Step 3 and perform surface treatment on the chip welding area 1 to prepare the finished product. Perform surface nickel-gold treatment on the chip welding area 1 of the multi-layer ceramic substrate obtained in Step 3. The surface nickel plating is electroless nickel plating in a sodium hypophosphite system. The components of the sodium hypophosphite electroless nickel plating solution are: 26 g / L of NiSO4·7H2O, 27 g / L of NaH2PO2·H2O, 17 g / L of CH3COONa, and 15 g / L of Na3C6H5O·2H2O. The nickel plating temperature is 83 °C, and the nickel plating time is 22 min. The components of the gold plating solution are: 2 g / L of KAuCN2, 14 50 g / L of C6H

[0040] 50 g / L of N2O7, 10 g / L of NaH2PO2·H2O, 3 g / L of NiCl2, and 80 g / L of NH4Cl. The gold plating temperature is 83 °C, the pH value of the gold plating solution is 5, and the gold plating time is 5 min. The stirring method during nickel plating and gold plating is air stirring. The thickness of the nickel layer after nickel plating is 4.5 μm, and the thickness of the gold layer after gold plating is 0.05 μm;

[0041] Example 2:

[0042] The present invention provides a structure and preparation method of an ultra-high thermal conductivity multi-layer ceramic substrate. Please refer to Figures 1-5 and includes a multi-layer ceramic substrate body. The multi-layer ceramic substrate body is composed of a double-sided aluminum-clad ceramic substrate and a single-sided aluminum-clad ceramic substrate. The graphic surface of the double-sided aluminum-clad ceramic substrate is the chip welding area 1. Both the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate include ceramic chips 2. The non-graphic surface of the double-sided aluminum-clad ceramic substrate is the flow channel layer 3, and the aluminum-clad layer of the single-sided aluminum-clad ceramic substrate is the water supply layer 4. Take double-sided aluminum-clad aluminum nitride ceramic substrates and single-sided aluminum-clad aluminum nitride ceramic substrates of the same size. Among them, the aluminum thickness of the chip welding area 1 on the graphic surface of the double-sided aluminum-clad aluminum nitride ceramic substrate is 0.3 mm, the aluminum thickness of the flow channel layer 3 on the non-graphic surface is 2.5 mm, the aluminum nitride ceramic thickness of the double-sided aluminum-clad aluminum nitride ceramic substrate is 4.0 mm, the aluminum thickness of the water supply layer 4 on the aluminum-clad surface of the single-sided aluminum-clad aluminum nitride ceramic substrate is 1.5 mm, and the aluminum nitride ceramic thickness of the single-sided aluminum-clad aluminum nitride ceramic substrate is 4.0 mm.

[0043] A preparation method of an ultra-high thermal conductivity multi-layer ceramic substrate structure includes the following steps:

[0044] Step 1, Graphic transfer: Transfer the graphics of the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate through film design, film pasting, exposure, and development. Through film design, paste the film and expose the double-sided aluminum-clad aluminum nitride ceramic substrate and the single-sided aluminum-clad aluminum nitride ceramic substrate. In the film design of the non-graphic surface of the double-sided aluminum-clad aluminum nitride ceramic substrate, the side length of each array square in the non-etching area is 0.1 mm, the distance between adjacent two squares is 0.1 mm, and the width of the process edge area is 4 mm;

[0045] Step 2, Etching: Etch the double-sided ceramic substrate and the single-sided ceramic substrate with aluminum etchant. Take the double-sided aluminum-clad aluminum nitride ceramic substrate and the single-sided aluminum-clad aluminum nitride ceramic substrate completed in Step 1 for etching. The etchant system is ferric chloride system, and the etching factor is 1;

[0046] Step 3, Friction stir welding: Take the double-sided ceramic substrate and the single-sided ceramic substrate obtained in Step 2 for friction stir welding to obtain a multi-layer ceramic substrate. Take the double-sided aluminum-clad aluminum nitride substrate and the single-sided aluminum-clad aluminum nitride substrate completed in etching in Step 2, and weld them at the process edges of the two substrates by friction stir welding. The rotation speed during friction stir welding is 1000 r / min, the welding speed is 70 mm / min, the elevation angle is 0°, the stirring head used for welding is a non-threaded conical stirring head, and the length of the stirring pin is 3.8 mm;

[0047] Step 4, Surface treatment: Take the multi-layer ceramic substrate obtained in Step 3 for surface treatment of the chip welding area 1 to prepare the finished product. Perform surface nickel-gold treatment on the chip welding area 1 of the multi-layer ceramic substrate obtained in Step 3. The surface nickel plating is electroless nickel plating with sodium hypophosphite system. The components of the sodium hypophosphite electroless nickel plating solution are: NiSO4·7H2O is 26 g / L, NaH2PO2·H2O is 27 g / L, CH3COONa is 17 g / L, Na3C6H5O·2H2O is 15 g / L, the nickel plating temperature is 82 °C, the nickel plating time is 22 min. The components of the gold plating solution are: KAuCN2 is 2 g / L, C6H 14 N2O7 is 50 g / L, NaH2PO2·H2O is 10 g / L, NiCl2 is 3 g / L, NH4Cl is 80 g / L, the gold plating temperature is 84 °C, the pH value of the gold plating solution is 5, the gold plating time is 5 min. The stirring methods during nickel plating and gold plating are both air stirring. The thickness of the nickel layer after nickel plating is 4.3 μm, and the thickness of the gold layer after gold plating is 0.06 μm;

[0048] Step 5, Drilling: Take the multi-layer ceramic substrate obtained in Step 3 for mechanical drilling. By mechanical processing, drill holes in the multi-layer ceramic substrate obtained after Step 4. The drilling position is at the center of the middle aluminum layer of the multi-layer ceramic substrate, and the drilling diameter is 1.2 mm.

[0049] Comparative Example 1:

[0050] Referring to Example 1, the difference is that: a multi-layer ceramic plate is prepared by a diffusion welding process, and the flow channel layer 3 and the water supply layer 4 are removed. The specific steps are as follows:

[0051] Step 1: Take double-sided aluminum-clad ceramic substrates and single-sided aluminum-clad ceramic substrates of the same size. The thickness of the thin aluminum surface of the double-sided aluminum-clad ceramic substrate is 0.2 mm, the thickness of the thick aluminum surface of the double-sided aluminum-clad ceramic substrate is 1.5 mm, the thickness of the ceramic chip 2 of the double-sided aluminum-clad ceramic substrate is 3.5 mm, the thickness of the aluminum surface of the single-sided aluminum-clad ceramic substrate is 1.5 mm, and the thickness of the ceramic chip 2 of the single-sided aluminum-clad ceramic substrate is 3.5 mm. Pretreat the double-sided aluminum-clad ceramic chip 2. After ultrasonic cleaning the surface impurities with acetone and roughening by sandblasting, a layer of alloy powder is cold-sprayed on the thick aluminum surface of the double-sided aluminum-clad ceramic substrate, and then the single-sided aluminum-clad ceramic substrate is diffusion-sintered and welded on the thick aluminum surface of the double-sided aluminum-clad ceramic substrate. The diffusion sintering process parameters are: temperature 500 °C, pressure 3 MPa, vacuum degree 0.4 Pa, heat preservation 1.5 h, heating rate 10 °C / min, and sample preparation.

[0052] Step 2: Perform surface nickel-gold treatment on the multi-layer ceramic substrate obtained in Step 1. The surface nickel plating is electroless nickel plating in a sodium hypophosphite system. The components of the sodium hypophosphite electroless nickel plating solution are: NiSO4·7H2O is 26 g / L, NaH2PO2·H2O is 27 g / L, CH3COONa is 17 g / L, Na3C6H5O·2H2O is 15 g / L, the nickel plating temperature is 83 °C, the nickel plating time is 20 min. The components of the gold plating solution are: KAuCN2 is 2 g / L, C6H 14 N2O7 is 50 g / L, NaH2PO2·H2O is 10 g / L, NiCl2 is 3 g / L, NH4Cl is 80 g / L, the gold plating temperature is 85 °C, the pH value of the gold plating solution is 5, the gold plating time is 7 min. The stirring methods during nickel plating and gold plating are both air stirring. The thickness of the nickel layer after nickel plating is 4.4 μm, and the thickness of the gold layer after gold plating is 0.05 μm.

[0053] Detection test:

[0054] Using the thermal cycling performance test, the multi-layer ceramic substrates prepared in Examples 1-2 and Comparative Example 1 are used as samples, and a TSE-12-A high and low temperature cycle test chamber is used for thermal cycling test. The parameter settings are: the cycle temperature is -40 °C to 125 °C, the test standard is GB / T 2423.22-2012 Environmental testing - Part 2: Test methods, Test N: Change of temperature, each sample is cycled 1500 times, and the roughness values of the nickel-gold surface of the samples are detected before and after cycling. The test temperature is room temperature. The experimental data obtained are as follows:

[0055]

[0056]

[0057] Conclusion:

[0058] During the thermal cycling test, due to the low yield strength of aluminum and the accumulation of thermal stress during the test process, the surface roughness of aluminum increases sharply. Therefore, the improvement of the feedback stress is carried out by comparing the change in surface roughness before and after the test.

[0059] Based on the surface roughness data before and after the thermal cycling test of the examples and comparative examples, it can be concluded that the internal flow channel layer 3 and the water supply layer 4 can significantly improve the heat conduction of the multi-layer ceramic substrate, with obvious stress improvement, solving the problems of increased warping and stress accumulation caused by thermal cycling, and greatly improving the reliability of power devices.

[0060] The present invention designs a multi-layer ceramic substrate structure of chip welding area 1 - ceramic chip 2 - flow channel layer 3 - water supply layer 4 - ceramic chip 2. The flow channel layer 3 provides cooling water to smooth the temperature gradient, and the internal design is an array of square grids, greatly increasing the heat dissipation contact area. In addition, through friction stir welding, defects such as cracks and pores generated during the aluminum-aluminum welding process are reduced. The product prepared by the present invention has excellent heat conduction effect, reduces the problems of thermal warping and stress accumulation caused by thermal cycling, and improves the thermal cycling reliability of power devices.

[0061] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0062] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application, according to the technical solution and its improvement concept of the present application, makes equivalent substitutions or changes, and should be covered by the protection scope of the present application.

Claims

1. A structure of a super-high thermal conductivity multi-layer ceramic substrate, comprising a multi-layer ceramic substrate body, characterized in that, The multi-layer ceramic substrate body is composed of a double-sided aluminum-clad ceramic substrate and a single-sided aluminum-clad ceramic substrate. The graphic surface of the double-sided aluminum-clad ceramic substrate is the chip welding area (1). Both the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate include ceramic chips (2). The non-graphic surface of the double-sided aluminum-clad ceramic substrate is the flow channel layer (3), and the aluminum-clad layer of the single-sided aluminum-clad ceramic substrate is the water supply layer (4).

2. The structure of a super-high thermal conductivity multi-layer ceramic substrate according to claim 1, wherein, The thickness of the ceramic chip (2) is 3 - 7 mm, the aluminum thickness of the chip welding area (1) is 0.1 - 0.4 mm, and the total thickness of the water supply layer (4) and the flow channel layer (3) is 2 - 4.5 mm.

3. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to any one of claims 1-2, characterized in that, It includes the following steps: Step 1, Graphic transfer: The double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate are subjected to graphic transfer through film design, film pasting, exposure, and development. Step 2, Etching: The double-sided ceramic substrate and the single-sided ceramic substrate are etched using an aluminum etching solution. Step 3, Friction stir welding: The double-sided ceramic substrate and the single-sided ceramic substrate obtained in Step 2 are subjected to friction stir welding to obtain a multi-layer ceramic substrate. Step 4, Surface treatment: The multi-layer ceramic substrate obtained in Step 3 is subjected to surface treatment on the chip welding area (1) to prepare the finished product. Step 5, Drilling: The multi-layer ceramic substrate obtained in Step 3 is subjected to mechanical drilling.

4. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to claim 3, characterized in that, In Step 1, the types of ceramic chips (2) of the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate include aluminum nitride ceramics, silicon nitride ceramics, and alumina ceramics.

5. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to claim 3, characterized in that, In Step 1, the film design of the non-graphic surface flow channel layer (3) of the double-sided aluminum-clad ceramic substrate has a full-etching area, a non-etching area, and a process edge area. The film design of the aluminum-clad surface of the single-sided aluminum-clad ceramic substrate has a semi-etching area and a process edge area. The non-etching area is arranged in an array of squares, and the side length of each square is 0.05 - 0.25 mm, and the distance between adjacent two squares is 0.05 - 0.2 mm. The full-etching area is completely etched. The process edge area is square, and the width of the process edge area is 3 - 5 m. The height difference between the semi-etching area and the process edge area is 1 / 2 of the thickness of the aluminum-clad layer of the single-sided aluminum-clad ceramic substrate.

6. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to claim 3, characterized in that, In Step 2, the aluminum etching solution is a ferric chloride system, and the etching factor is 1 - 1.

5.

7. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to claim 3, characterized in that, In Step 3, the friction stir welding is to weld the process edges of the double-sided aluminum-clad ceramic substrate and the single-sided aluminum-clad ceramic substrate. The rotation speed during friction stir welding is 800 - 1000 r / min, the welding speed is 50 - 75 mm / min, the elevation angle is 0°, the stirring head used for welding is a non-threaded conical stirring head, the length of the stirring pin is 2.5 - 4.5 mm, the length of the stirring pin matches the width of the process edge, and the length of the stirring pin is slightly less than the width of the process edge.

8. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to claim 3, characterized in that, In step 4, the surface treatment is electroless nickel immersion gold treatment. The surface nickel plating is electroless nickel plating in a sodium hypophosphite system. The components of the sodium hypophosphite electroless nickel plating solution are: 25 - 30 g / L of NiSO4·7H2O, 25 - 30 g / L of NaH2PO2·H2O, 15 - 20 g / L of CH3COONa, and 10 - 20 g / L of Na3C6H5O·2H2O. The components of the gold plating solution are: 0.5 - 2.5 g / L of KAu(CN)2, 45 - 55 g / L of C6H14N2O7, 8 - 12 g / L of NaH2PO2·H2O, 1 - 3 g / L of NiCl2, and 70 - 80 g / L of NH4Cl.

9. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to claim 8, characterized in that, In step 4, the nickel plating temperature is 78 - 85 °C, the nickel plating time is 20 - 25 min, the gold plating temperature is 83 - 88 °C, the pH value of the gold plating solution is 5 - 6, the gold plating time is 3 - 7 min. The stirring method during both nickel plating and gold plating is air stirring. The thickness of the nickel layer after nickel plating is 4 - 6 μm, and the thickness of the gold layer after gold plating is 0.04 - 0.06 μm.

10. The preparation method of a super-high thermal conductivity multi-layer ceramic substrate structure according to claim 3, characterized in that, In step 5, the aperture of the mechanical punching is 1.0 - 2.0 mm, and the punching position is at the center of the aluminum layer in the middle of the multi-layer ceramic substrate.

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