Electronic device, ceramic substrate and preparation method thereof

Abstract

The invention provides an electronic device, a ceramic substrate and a preparation method thereof, and relates to the technical field of semiconductors. The ceramic substrate comprises a ceramic base body and a liquid channel layer, the liquid channel layer is arranged in the ceramic base body, the liquid channel layer and the ceramic base body are integrally sintered and formed, the liquid channel layer comprises a liquid channel, the liquid channel is used for containing a cooling medium, and the liquid channel extends in the ceramic base body along a three-dimensional space path. The preparation method of the ceramic substrate comprises the following steps: preparing slurry containing ceramic powder, preparing a sacrificial template matched with a target liquid channel in shape, pouring the slurry to coat the sacrificial template, filling a mold with the slurry to obtain a ceramic blank, removing the sacrificial template to form a hollow channel in the ceramic blank, and sintering to form the ceramic substrate with the liquid channel. The electronic device comprises the ceramic substrate, a component and a liquid cooling circulation system.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to an electronic device, a ceramic substrate, and a method for preparing the same. Background Technology

[0002] Ceramic materials possess high thermal conductivity, excellent insulation properties, and good high-temperature resistance, and have been widely used in power modules, electronic packaging, and heat dissipation substrates. However, with the continuous increase in power density of automotive power devices, traditional heat dissipation methods that use metal cold plates combined with direct bonded copper (DBC), direct plating copper (DPC), or active metal brazing (AMB) structures require multi-layer interface heat transfer, making it difficult to achieve both efficient heat dissipation and system lightweighting.

[0003] In recent years, some studies have attempted to construct liquid channels within ceramics to achieve modular, integrated heat dissipation structures. One technical approach involves first fabricating channels on one or more ceramic substrates using machining, etching, or other methods. These substrates are then joined together using welding, sintering, or other methods, forming the liquid channels. The drawbacks of this approach are its complex process flow, numerous interface layers, and the inherent risk of liquid leakage. Another approach employs a sacrificial material layering and sintering method. During the preparation of the ceramic substrate preform, ceramic slurry and sacrificial materials such as paraffin wax are laid using a tape casting method to create a ceramic preform with a flow channel structure in a single step. The sacrificial materials are then volatilized through sintering, forming flow channels within the ceramic substrate. The disadvantages of this approach include the sacrificial materials' susceptibility to deformation and the difficulty in precisely controlling their dimensions.

[0004] Overall, the channel forms formed by existing solutions are still mainly planar trenches, which limits the structural continuity and three-dimensional designability. It is difficult to directly obtain an integrated and reliably sealed internal liquid channel in a simple process and with a clear interface during the ceramic forming stage, which to some extent restricts the further improvement of the heat dissipation performance and long-term reliability of high power density power modules. Summary of the Invention

[0005] In a first aspect, the present invention provides a ceramic substrate, comprising a ceramic matrix and a liquid channel layer, wherein the liquid channel layer is disposed inside the ceramic matrix and integrally sintered with the ceramic matrix, the liquid channel layer includes liquid channels for containing a cooling medium, and the liquid channels extend along a three-dimensional spatial path inside the ceramic matrix.

[0006] In optional implementations, the three-dimensional spatial path includes any one or any combination of straight, serpentine, loop, circular, tree-like, grid-like, multi-layered, three-dimensional serpentine, multi-layered misaligned, spiral, and fully three-dimensional spiral structure; or, the three-dimensional spatial path includes at least two paths whose axes are not coplanar. Alternatively, the liquid channel can be prefabricated in situ during the preform forming stage of the ceramic matrix using a sacrificial template, and then formed after removing the sacrificial template and sintering. Alternatively, the liquid channel may include at least one main channel, or may also include at least one branch channel and a confluence area or outlet channel; preferably, the main channel or confluence area is provided with a turbulence structure; Alternatively, the cross-section of the liquid channel can be rectangular, trapezoidal, annular, circular, polygonal, or any combination of the above shapes.

[0007] In an optional embodiment, the ceramic substrate is a planar block structure with all surfaces being flat; Alternatively, the ceramic matrix is ​​a block structure with at least one curved surface, where the curved surface has unidirectional or bidirectional curvature. Alternatively, the ceramic matrix may be a bent plate structure, which may be a single or multiple segmented planar bending shape or a multiple segmented spatial bending shape. Alternatively, the ceramic matrix may have a ring-shaped, arc-shaped, fan-shaped, ring-band-shaped, ring-step-shaped, or hollow cylindrical structure.

[0008] The ceramic substrate provided by this invention has the following advantages: the liquid channel and the ceramic substrate are integrally sintered, allowing for the direct acquisition of a structurally integrated and reliably sealed internal liquid channel during the ceramic substrate forming stage with a simple process and clear interface. The liquid channel extends along a three-dimensional spatial path within the ceramic substrate. The liquid channel offers high three-dimensional design flexibility, allowing for the design of specific three-dimensional spatial paths based on the heat dissipation requirements of high-power-density power modules, thereby improving the heat dissipation performance and long-term reliability of the ceramic substrate.

[0009] Secondly, the present invention provides a method for preparing a ceramic substrate, comprising: Preparation of a slurry containing ceramic powder; Prepare a sacrificial template that matches the shape of the target liquid channel; A sacrificial template is fixed inside a mold, and slurry is poured in to cover the sacrificial template and fill the mold, thus obtaining a ceramic body. Remove the sacrificial template to form a hollow channel within the ceramic body; Sintering transforms the hollow channels within the ceramic blank into liquid channels, thus forming a ceramic substrate from the ceramic blank.

[0010] In an optional embodiment, the sacrificial template is a planar structure template, prepared by injection molding, compression molding or extrusion; Alternatively, the sacrificial template can be a three-dimensional structural template, which can be prepared by three-dimensional printing technology, multi-segment splicing or combination molding; Alternatively, the sacrificial template may be made of a controllable thermoplastic or thermosetting material, preferably paraffin wax, polylactic acid, polymethyl methacrylate, polystyrene or photosensitive resin; Alternatively, the surface of the sacrificial template may be textured or grooved to form the corresponding texture or groove within the liquid channel.

[0011] In an optional embodiment, when preparing a slurry containing ceramic powder, the ceramic powder is dispersed in a liquid phase to obtain a suspension with a solid content of 50 to 70% by volume, wherein the liquid phase contains monomers, crosslinking agents, dispersants and initiation systems. Preferably, the liquid phase is deionized water, and the dispersant is an anionic dispersant, preferably ammonium polyacrylate; or, the liquid phase is a non-aqueous solvent selected from anhydrous ethanol, isopropanol and mixtures thereof, and the dispersant is a phosphate ester or polyether modified non-aqueous dispersant. Preferably, the monomer is an acrylic monomer or an acrylamide monomer, and the crosslinking agent is a diacrylate crosslinking agent; Preferably, the initiation system is a redox / thermal initiation combination, preferably ammonium persulfate / tetramethylethylenediamine or benzoyl peroxide / tertiary amine, and preferably achieves a controllable gel time of 5 to 20 minutes at 25 to 35 degrees Celsius.

[0012] In an optional embodiment, a gel solidification step is also included: the slurry is volumetrically gelled in the mold by redox initiation and / or thermal initiation at room temperature or slightly elevated temperature to obtain a ceramic green body with self-supporting strength.

[0013] In an optional embodiment, after obtaining the ceramic blank, a post-processing of the blank is performed, including drying the ceramic blank. Alternatively, it may include: at least partially removing the sacrificial template; preferably, during the removal of the sacrificial template, venting holes or connecting holes are provided on the periphery of the ceramic blank or in a non-functional area to facilitate the discharge of material from the sacrificial template; Alternatively, it may include: machining the ceramic body to obtain predetermined dimensional accuracy, surface roughness, surface microstructure, or through-hole structure.

[0014] In an optional embodiment, when removing the sacrificial template, the ceramic body is placed in a degreasing atmosphere for degreasing treatment to remove the organic components in the sacrificial template and slurry; Preferably, the degreasing atmosphere can be air, an inert gas, or a reducing atmosphere; Preferably, a multi-stage heating and heat preservation method is used during the degreasing process; Preferably, during the degreasing process, venting holes or connecting holes are provided on the outer periphery or non-functional areas of the ceramic blank to facilitate the discharge of organic components from the material and slurry of the sacrificial template.

[0015] The ceramic substrate preparation method provided by this invention has the following beneficial effects: the sacrificial template can be prepared into a shape that matches the target liquid channel, which has extremely high design flexibility. It can be designed into a specific shape that best achieves the function according to the heat dissipation requirements of the ceramic substrate, and obtain a variety of liquid channels including planar and three-dimensional structures. In particular, it can obtain liquid channels with complex structures that cannot be obtained by traditional processing technology, thus achieving specific heat dissipation requirements. The process of casting slurry to cover the sacrificial template and fill the mold can obtain a ceramic preform with a complex shape using the mold. The process of slurry covering the sacrificial template and filling the mold can fully combine the slurry and the sacrificial template, and the liquid channel can obtain an accurate contour and excellent surface quality.

[0016] Thirdly, the present invention provides an electronic device, which includes components and a liquid cooling circulation system, and further includes a ceramic substrate according to any of the foregoing embodiments or a ceramic substrate prepared by a method for preparing a ceramic substrate according to any of the foregoing embodiments. The connection between the liquid cooling circulation system and the liquid channel of the ceramic substrate is made, and the liquid cooling circulation system allows the cooling medium to flow in the liquid channel; Preferably, the liquid cooling circulation system includes a pump, a heat exchanger, and liquid piping; Preferably, the cooling medium is water, an aqueous solution of ethylene glycol, a dielectric coolant, or a synthetic oil.

[0017] The electronic device provided by this invention has the following beneficial effects: the components in the electronic device can be fully cooled through the liquid cooling circulation system and the ceramic substrate, reducing the overall thermal resistance and improving the system integration and engineering adaptability. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a ceramic substrate in one embodiment of this application; Figure 2 This is a schematic diagram of a ceramic substrate in one embodiment of this application; Figure 3 This is a cross-sectional schematic diagram of a "double-sided cooling" ceramic substrate in one embodiment of this application; Figure 4 This is a cross-sectional schematic diagram of a "heat spreader" ceramic substrate in one embodiment of this application; Figure 5 This is a cross-sectional schematic diagram of an "S-shaped" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 6 This is a cross-sectional schematic diagram of a "U-shaped" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 7 This is a cross-sectional schematic diagram of a "cylindrical turbulence type" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 8 This is a cross-sectional schematic diagram of a "branch-type" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 9 This is a cross-sectional schematic diagram of a "three-dimensional branch type" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 10 This is a cross-sectional schematic diagram of a "three-dimensional spiral" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 11 This is a cross-sectional schematic diagram of a "heat spreader" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 12 This is a cross-sectional schematic diagram of a "curved" sacrificial template and its ceramic substrate in one embodiment of this application; Figure 13 This is a schematic diagram of a process flow for preparing a ceramic substrate using an aqueous gel casting method according to one embodiment of this application; Figure 14 This is a schematic diagram of the process flow for preparing a ceramic substrate using an organic gel casting method according to one embodiment of this application; Figure 15 This is a schematic diagram of the process flow of a method for preparing a ceramic substrate according to one embodiment of this application.

[0020] Icons: 10-Ceramic substrate; 101-Circuit connection hole; 102-Mounting hole; 201-Liquid cooling channel; 202-Breakflow structure; 30-Insulation layer; 301-Insulating island; 401-Copper plating; 402-Components; 403-Brazing; 404-Wire; 405-Heat spreader; 50-Liquid flow channel connection port; 60-Sacrificial template. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0026] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] Example 1 Figure 1 This is a schematic diagram of a ceramic substrate in one embodiment of this application.

[0029] like Figure 1 As shown, this application provides a ceramic substrate, including a ceramic substrate 10, circuit connection holes 101, mounting holes 102, a liquid flow channel layer, a liquid cooling channel 201, an insulating layer 30, a functional layer 40, copper plating 401, components 402, brazing 403, wires 404, and a liquid flow channel connection port 50.

[0030] The ceramic substrate 10 is a block structure integrally sintered and can simultaneously perform the triple functions of mechanical support, electrical insulation, and heat conduction and dissipation. By integrating the liquid cooling channel 201 into the interior of the ceramic substrate 10, the ceramic substrate of this application achieves efficient cooling of the power component 402 while maintaining good electrical insulation and mechanical strength.

[0031] The ceramic matrix 10 can be made of alumina, aluminum nitride, silicon nitride, silicon carbide, alumina / zirconia composite ceramics, aluminum nitride / silicon nitride composite ceramics, and combinations thereof to achieve high thermal conductivity and insulation strength. In some embodiments, thermal conductivity, dielectric strength, and mechanical toughness can be traded off and optimized according to different application scenarios.

[0032] Preferably, the ceramic matrix 10 is alumina ceramic. Alumina ceramic has a mature process, abundant raw material sources, moderate cost, and good mechanical strength and thermal shock resistance, making it suitable for large-scale industrial applications such as automotive power modules.

[0033] Further preferably, the ceramic matrix 10 is an alumina / zirconia composite ceramic. Since zirconia has high fracture toughness, introducing an appropriate amount of zirconia helps improve the crack resistance and mechanical impact resistance of the ceramic substrate, thereby reducing crack initiation and propagation under harsh conditions such as vibration and thermal cycling, and improving the long-term reliability of the product.

[0034] Preferably, the ceramic matrix 10 has a dense polycrystalline structure, and its relative density is preferably not less than 95%. More preferably, the relative density of the ceramic matrix 10 is not less than 97%, so as to ensure that the channel wall of the liquid cooling channel 201 has sufficient mechanical strength and airtightness, and to prevent leakage, penetration or microcrack propagation under high pressure liquid cooling conditions.

[0035] In terms of structural dimensions, the thickness of the ceramic substrate 10 is typically in the range of a few millimeters, such as 2 mm, 3 mm, or 5 mm. The specific thickness can be comprehensively designed based on the chip packaging height, electrical insulation requirements, liquid flow channel layout, and overall structural strength. In some embodiments, to balance insulation safety distance and low thermal resistance, the ceramic substrate 10 can be divided into an insulating layer 30 region near the functional layer 40 and a heat dissipation layer region near the liquid cooling channel 201. The thickness of the different regions can be designed differently.

[0036] The planar dimensions (length × width) of the ceramic substrate 10 are determined according to the corresponding chip array layout, the outline of the power module, and the layout of the surface copper-clad circuit pattern 401, and can range from tens of millimeters to hundreds of millimeters. For example, in automotive inverter applications, typical dimensions of the ceramic substrate can be 30 mm × 50 mm, 50 mm × 80 mm, 80 mm × 120 mm, etc., and this application does not limit these dimensions.

[0037] like Figure 1 As shown, a circuit connection hole 101 is provided in the ceramic substrate for forming a circuit path or for mounting specific components. The circuit connection hole 101 generally extends along the thickness direction of the ceramic substrate, and its axis is basically perpendicular to the main plane of the ceramic substrate. The diameter of the circuit connection hole 101 can be designed according to actual needs, for example, to accommodate connectors such as solder leads, crimp terminals, or metal studs.

[0038] In some embodiments, the inner wall of the circuit connection hole 101 may be metallized to form a through-hole, thereby enabling electrical connection between the surface circuit and external leads or busbars. To ensure electrical safety, the circuit connection hole 101 needs to maintain a predetermined minimum distance from the liquid cooling channel 201 to ensure sufficient creepage distance and clearance between the coolant and the power lines, preventing electrical breakdown or flashover failure in high humidity, high pressure, or polluted environments.

[0039] Mounting holes 102 can also be integrally formed at the edge or appropriate location of the ceramic substrate. Mounting holes 102 are used for mechanical connection and positioning with the module housing, cooling system bracket, or mounting platform. Mounting holes 102 can be through holes or blind holes, and their diameter can be designed according to the bolt, stud, or rivet structure, such as corresponding to standard fastener specifications like M3 and M4. In some embodiments, the area around the mounting holes 102 can be appropriately thickened or reinforced to improve local stress resistance under tightening loads and prevent cracking under assembly preload or service vibration conditions.

[0040] In specific implementations, the circuit connection hole 101 and the mounting hole 102 can be formed by mechanical processing of the ceramic substrate (such as drilling, laser drilling or ultrasonic processing); or they can be reserved in the ceramic forming stage by pre-making voids, inserting rod-shaped fillers, etc., and removed after sintering to obtain higher hole wall density and flatness. This application does not impose any restrictions on this.

[0041] The liquid flow channel layer is arranged inside the ceramic substrate. During the ceramic forming stage, the liquid flow channel layer is prefabricated in situ using a sacrificial template 60. After sintering, it forms a hollow channel completely encapsulated by ceramic, thus eliminating the need for subsequent mechanical drilling or metal sealing plates to obtain the internal liquid cooling network. This integrated structure effectively eliminates the interface layer and sealing material between the traditional cold plate and the ceramic substrate, reducing thermal resistance and the risk of potential liquid leakage.

[0042] The liquid flow channel layer consists of a main flow channel, multiple branch flow channels, and a confluence region. The cross-sectional dimensions of the main flow channel and branch flow channels of the liquid flow channel layer can be flexibly designed according to the application, and can vary from 100 μm to several millimeters, for example, dimensions such as 100 μm, 150 μm, 300 μm, 600 μm, 900 μm, 1 mm, 1.2 mm, and 2 mm.

[0043] Preferably, the cross-sectional dimensions of the main flow channel and branch flow channel of the liquid flow channel layer are 200 μm to 1 mm. More preferably, the cross-sectional dimensions of the main flow channel and branch flow channel of the liquid flow channel layer are 500 μm to 700 μm, so as to achieve a good balance between heat exchange efficiency and flow pressure drop, and to meet the thermal management requirements under typical coolant flow rate and module area.

[0044] In some embodiments, the cross-sectional shape of the liquid flow channel layer can be rectangular, trapezoidal, circular, elliptical, polygonal, or any combination of the above shapes. Different cross-sectional shapes can be used to adjust the local flow velocity distribution, heat exchange area, and processing difficulty. For example, rectangular cross-sections are easy to process using sheet templates, while circular or near-circular cross-sections are beneficial for reducing flow resistance and stress concentration.

[0045] In some embodiments, the liquid flow channel layer can extend along any direction of the ceramic substrate—length, width, or thickness—forming a straight, S-shaped, loop, or ring structure. Through proper design, a single-channel series, parallel distribution, confluence network, or multi-layered interlaced three-dimensional flow channel network can be formed to balance the heat dissipation requirements and cooling uniformity of different areas. This application does not limit the flow channel structure.

[0046] In some embodiments, to accommodate the distribution of different heat-generating areas, several branch flow channels can be arranged for the chip array, so that each power chip or chip group has at least one local enhanced heat transfer area below it, in order to reduce chip temperature unevenness and local hot spots, and improve the output capability and reliability of the module.

[0047] In some embodiments, protrusions, turbulence structures 202, surface textures, or variable cross-section structures can be prefabricated on the inner wall of the main flow channel or branch flow channel using a sacrificial template 60 to enhance fluid turbulence and improve the convective heat transfer coefficient. For example, periodic ribs, ridges, or narrowed sections can be formed on the inner wall of the flow channel to break laminar flow and promote fluid mixing. This application does not limit the specific form of the turbulence structure 202.

[0048] The insulating layer 30 is located between the liquid flow channel layer and the functional layer 40. It is an intact area in the ceramic substrate that is not perforated by the flow channel, and its material is usually the same as that of the ceramic substrate 10. The insulating layer 30 is mainly used to provide reliable electrical insulation between the coolant and the high-voltage power device, while ensuring a low thermal resistance path.

[0049] The thickness of the insulation layer 30 is determined based on the withstand voltage rating and the required insulation strength. For example, for automotive 400 V to 800 V systems, it is typically designed to be 0.3 mm to 1.5 mm. In applications with higher voltage ratings or higher insulation safety margin requirements, the thickness of the insulation layer 30 can be further increased; while in low-voltage or locally low-voltage areas, it can be appropriately thinned to reduce thermal resistance.

[0050] The planar dimensions of the insulating layer 30 typically cover all high-voltage power device areas, ensuring that the coolant does not form breakdown paths through ceramic defects or weak areas with concentrated edge electric fields as it flows through the channels, thus balancing creepage distance, clearance, and thermal resistance requirements. In some embodiments, the insulating layer 30 can employ various thickness combinations, such as forming locally thickened insulating island structures below high-voltage areas while retaining thinner insulating layers 30 below low-voltage or grounded areas, to achieve zoned optimization design.

[0051] The functional layer 40 is formed on one or both outer surfaces of the ceramic substrate 10, and is used to support power devices, circuit connections, or signal acquisition, etc., and can integrate parts including copper plating 401, components 402, solder 403, and wires 404. Figure 1 As shown, functional layer 40 can be partitioned and arranged according to specific circuit topology and packaging scheme.

[0052] The copper cladding 401 can be prepared using one or more of the following forms: DPC copper layer, DBC copper layer, AMB metal layer, sputtered + electroplated metal layer, thick film circuit layer or composite conductive layer; the ceramic substrate structure of this application is essentially a "liquid-cooled integrated ceramic carrier", which is not limited to a specific metallization process and can be flexibly selected according to different needs and packaging routes.

[0053] The thickness of the copper cladding 401 can be flexibly selected according to current density, mechanical reliability, and soldering process requirements, for example, it can be 35 μm, 70 μm, 200 μm, 250 μm, 300 μm, 500 μm, 800 μm, and 1000 μm. Preferably, for high-current power modules, the thickness of the copper cladding 401 is 70 μm to 500 μm to achieve a balance between conductive cross-section and processing feasibility. In some embodiments, different copper thicknesses can be used in different areas; for example, a thicker copper layer is used in the chip area to reduce resistance and enhance heat dissipation, while a thinner copper layer is used in the control signal area to facilitate fine wiring.

[0054] Component 402 may include IGBT chips, MOSFET chips, Schottky diodes, capacitors, inductors, resistors, driver ICs, control ICs, temperature sensors, current sampling resistors, etc. This application does not limit the type of component 402. Depending on the different package forms and power ratings of component 402, different interconnection processes and fixing methods can be selected, for example: • When component 402 is an IGBT chip or a MOSFET chip, the back of the chip can be fixed to the copper cladding 401 by soldering 403 (such as SnAgCu solder, sintered silver, etc.); • When component 402 is a discrete resistor or a small component, it can be soldered together using pads and wires 404. For corresponding control ICs or sensors, electrical connections can be achieved using processes such as wire bonding and flip-chip soldering.

[0055] In some embodiments, a nickel / gold plating layer may be further provided on the copper cladding 401 to improve solderability and corrosion resistance, which is particularly suitable for high-reliability automotive-grade devices.

[0056] The liquid flow channel connection 50 is located on the edge or surface of the ceramic substrate 10 and communicates with the liquid flow channel layer for connecting to an external liquid cooling circulation system. The liquid flow channel connection 50 can adopt a threaded, embedded, brazed 403 type, or sealing ring structure to ensure sealing performance and mechanical stability under high pressure and thermal cycling conditions. Figure 1 The liquid flow channel connection port 50 shown is threaded, which facilitates quick connection with standard fittings or pipelines.

[0057] The orifice size of the liquid flow channel connection 50 can be selected according to the cooling flow requirements and the standard piping design of the system, such as 3 mm, 4 mm, 5 mm, etc. In some embodiments, the periphery of the liquid flow channel connection 50 can be designed with ceramic steps or grooves to embed O-rings or metal gaskets to form multiple seals; a metal reinforcing ring or a locally thickened area can also be set around the interface to improve the mechanical shock resistance and long-term sealing reliability of the interface area.

[0058] Example 2 Figure 2 This is a schematic diagram of a liquid-cooled integrated irregular ceramic substrate in one embodiment of this application.

[0059] This embodiment is in Figure 1 Based on the planar structure shown, the design is further expanded by using three-dimensional forming and sacrificial template 60 technology to extend the ceramic substrate into a non-circular ceramic part with spatial curvature and complex three-dimensional flow channels, in order to meet the future demand for customized structure and space utilization in highly integrated packaging.

[0060] like Figure 2 As shown, the ceramic substrate in this embodiment includes a curved ceramic substrate 10, a liquid channel layer embedded within the curved ceramic substrate 10, an insulating layer 30 disposed between the liquid channel layer and the functional layer 40, an insulating island 301, a functional layer 40 disposed on the curved surface, and a liquid channel connection port 50, etc. For ease of explanation, this embodiment is similar to... Figure 1 Identical or similar functional units may use the same or corresponding designations, and their structure and function can be referenced. Figure 1 The description of the embodiments will not be repeated here; only the differences and the key points of this embodiment will be explained.

[0061] Preferably, the ceramic substrate 10 is a curved or irregularly shaped block structure integrally sintered, and its shape can have unidirectional or bidirectional curvature, such as: cylindrical surface, conical surface, spherical surface, ellipsoidal surface, saddle surface, etc.; it can also be a bent plate-like structure, such as L-shaped, U-shaped, Ω-shaped, or a spatially bent shape with multiple bends. In addition, the ceramic substrate 10 can also be a ring-shaped, arc-shaped, fan-shaped, ring-shaped, ring-stepped, or hollow cylindrical structure, used to fit motor housings, cylindrical battery modules, tubular heat sinks, or other three-dimensional mounting interfaces. This application does not limit the specific spatial shape of the ceramic substrate 10, as long as an internal flow channel network communicating with the external cooling circuit can be formed within the ceramic substrate, it falls within the protection scope of this application.

[0062] In a preferred embodiment, the ceramic substrate 10 is an arc-shaped plate structure, and its outer arc surface or inner arc surface can match the stator core of the motor or the outer circle of the motor housing, thereby realizing the power module layout that "bends with the housing".

[0063] A key feature of this embodiment is that the liquid flow channel layer is a three-dimensional flow channel structure, which can be arranged three-dimensionally along the spatial shape of the curved ceramic substrate 10. Figure 1 Unlike the "planar + thickness direction" flow channels, the liquid flow channel layer can not only extend in the length and thickness directions of the ceramic substrate 10, but also continuously bend and turn in the arc, circumferential or axial directions to conform to the curved surface, forming a three-dimensional flow channel network with spatial curvature.

[0064] Specifically, the liquid flow channel layer may include: a main flow channel extending along the curved surface direction, branch flow channels distributed in a ring or partially around a specific area (such as a chip array, coil area, or power busbar), and a convergence area that merges the branches and leads them to the liquid flow channel connection port 50. The cross-sectional dimensions of the flow channel can be similar to those of a planar structure.

[0065] In a preferred embodiment, because Figure 2 The ceramic substrate 10 shown is a curved or irregularly shaped structure, but many power chips, driver ICs, and other components 402 are still in planar package form. To ensure package reliability and soldering process window, this application introduces an insulating island 301 in the curved functional layer region. Figure 2 As shown, a relatively flat insulating island 301 is designed locally on the outer surface of the curved ceramic substrate 10. This insulating island is a locally thickened area in the ceramic substrate that is not penetrated by the flow channel, and is used to mount planar chip-type components 402.

[0066] The planar dimensions and height of the insulating island 301 can be customized according to the package size, pad distribution, and withstand voltage requirements of the target chip. For example, multiple insulating islands 301 of different heights or sizes can be arranged on the same curved ceramic substrate 10 to match IGBT chips, MOSFET chips, capacitors, or inductors of different sizes. For high-voltage devices requiring high creepage distances and clearances, the corresponding islands can be designed with thicker insulating layers 30; while for low-voltage or signal-level devices, the corresponding islands can be appropriately thinned to reduce thermal resistance.

[0067] Similarly, for other types of components 402, such as vertical package modules, through-hole capacitors, busbar connection terminals, etc., steps, grooves, or local planar areas of corresponding shapes and heights can be designed on the outer surface of the curved ceramic substrate 10 to facilitate device installation, soldering, and electrical connection. Through such a "local planar + overall curved surface" design, this application maintains the advantages of the three-dimensional irregular structure of the ceramic substrate while still being compatible with existing mainstream planar packaging and assembly processes, significantly reducing the cost of industrial upgrading.

[0068] The functional layer 40 is formed on the outer surface or a portion of the outer surface of the curved ceramic substrate 10, and can be used with... Figure 1 The same copper-clad 401 process system as the embodiments includes, but is not limited to: DBC copper layer, DPC copper layer, AMB metal layer, thick film circuit layer, sputtering + electroplating metal layer, or a combination of multiple processes. The curved ceramic structure of this application has good compatibility with metallization processes. It can be continuously laid with copper-clad 401 on the entire curved surface to form a large-area current loop or heat-spreading copper plate; or it can be locally metallized only in the insulating island 301 and its adjacent area to form power chip pads, control signal traces, and sensing circuits.

[0069] Figure 2 The illustrated embodiments demonstrate that the ceramic substrate proposed in this application is not only suitable for conventional flat panel structures, but can also be extended to various curved and irregularly shaped ceramic structures through the sacrificial template 60 and three-dimensional forming process, and a three-dimensional liquid-cooling channel network 201 is constructed internally. By introducing structures such as insulating layer islands 30, local planes, and multi-height steps, this application can mount traditional planar packaged chips and other components 402 on three-dimensional irregularly shaped ceramic substrates, achieving high structural freedom, high integration, and high customization capabilities, providing a universal liquid-cooled ceramic packaging platform for future electric drive systems, automotive power modules, and other high-power-density electronic devices.

[0070] Example 3 Figure 3 This is a cross-sectional schematic diagram of a "double-sided cooling" ceramic substrate in one embodiment of this application.

[0071] This embodiment is in Figure 1 Based on the planar liquid cooling structure shown, further optimization is achieved by setting functional layers on both sides of the ceramic substrate and encapsulating components 402, and arranging three-dimensional double-layer liquid cooling channels 201 inside the ceramic. This enables simultaneous liquid cooling of components 402 on both the upper and lower sides, significantly improving the packaging integration and power density per unit area. It is particularly suitable for application scenarios with stringent requirements for size, weight and power density.

[0072] In this embodiment, the ceramic substrate has an overall approximately symmetrical "sandwich" structure, with a liquid flow channel layer in the middle. An upper insulating layer 30 and a lower insulating layer 30 are respectively disposed on both sides of the insulating layer 30. An upper functional layer 40 and a lower functional layer 40 are formed on the outer side of the insulating layer 30. Both the upper and lower functional layers 40 can adopt a copper-clad structure 401, and power chips, driver devices, or other components 402 are packaged on them. This allows the same ceramic substrate to simultaneously bear the functions of device support and heat dissipation on both the upper and lower sides, thereby achieving double-sided device packaging and double-sided heat dissipation while maintaining a basically unchanged ceramic volume.

[0073] The liquid flow channel layer is arranged in the middle region of the ceramic substrate 10, between the upper insulating layer 30 and the lower insulating layer 30, so that the coolant can provide a short-distance heat exchange path for both the device area of ​​the upper functional layer 40 and the device area of ​​the lower functional layer 40.

[0074] In some embodiments, the upper and lower insulating layers 30 do not need to be completely symmetrical. For example, when one side is a high-voltage power device area and the other side is a low-voltage drive or control device area, the high-voltage side insulating layer 30 can be designed to be thicker and the low-voltage side insulating layer 30 can be designed to be thinner, so as to reduce thermal resistance as much as possible while meeting the insulation safety distance and achieve the purpose of zoning optimization.

[0075] Example 4 Figure 4 This is a cross-sectional schematic diagram of the "heat spreader 405 type" ceramic substrate in one embodiment of this application.

[0076] This embodiment is in Figure 1 Based on the planar liquid cooling structure shown, further optimization is achieved by integrating a heat spreader 405 at the bottom of the ceramic substrate and constructing a three-dimensional flow channel inside the ceramic. This allows the same coolant to complete the initial heat absorption on the side near the chip layer and then achieve secondary heat exchange on the side near the heat spreader 405, thereby forming a thermal management path of dual-sided synergistic cooling, which significantly improves heat dissipation efficiency and temperature uniformity.

[0077] One of the core structures in this embodiment is the bottom heat spreader 405 disposed on the lower surface of the ceramic substrate 10. The heat spreader 405 is used to rapidly diffuse heat from the upper chip area and coolant in the planar direction, homogenizing the temperature of the coolant and providing a second heat dissipation interface for the entire substrate. The heat spreader 405 can be made of a metal or composite material with high thermal conductivity, such as copper, copper alloys, copper-molybdenum, copper-tungsten, copper-graphite composites, aluminum, or aluminum alloys. Preferably, the heat spreader 405 is a copper or copper-molybdenum composite heat spreader 405 to obtain higher in-plane thermal conductivity and good mechanical stiffness. In some embodiments, the heat spreader 405 can be a multilayer composite structure, such as Cu / Mo / Cu or Cu / graphite / Cu, to further optimize thermal diffusion performance and thermal expansion matching performance.

[0078] The thickness of the heat spreader 405 can be designed according to the module size and heat dissipation requirements. It is usually 0.3 mm to 5 mm, preferably 0.5 mm to 3 mm, so as to control the overall structural height and weight while enhancing heat dissipation capacity.

[0079] The heat spreader 405 and the ceramic substrate 10 can be connected in various ways, such as by active metal brazing 403, diffusion welding, intermediate brazing 403 in the metallization layer, or metal adhesive bonding, to form an artificial metallurgical or high-strength adhesive interface. Preferably, one or more metallization coatings are first formed on the bottom surface of the ceramic substrate 10, and then the heat spreader 405 is integrally welded to the bottom surface of the ceramic substrate using active metal brazing 403 or high-temperature brazing filler metal, forming a large-area, low-thermal-resistance, and airtight connection structure.

[0080] Figure 4 Another important feature of the illustrated embodiment is that the liquid flow channel layer 2 forms a three-dimensional flow channel with multiple layers distributed vertically within the ceramic substrate 10. The liquid flow channel layer not only extends within the plane of the ceramic substrate, but also forms upper and lower flow channels of different heights in the thickness direction, and is interconnected through vertical connecting sections.

[0081] By adjusting the cross-sectional dimensions, length ratio, channel spacing, and vertical connection position of the upper and lower flow channels, this embodiment can flexibly balance heat exchange efficiency and flow pressure drop, achieving customized design for different power modules, different chip arrangements, and different cooling media.

[0082] The aforementioned three-dimensional flow channel structure is prefabricated integrally using a three-dimensional sacrificial template 60 introduced during the ceramic forming stage. The sacrificial template 60 itself has staggered layers and a folded-back shape. By controlling the geometry and spatial position of the template, a three-dimensional serpentine flow channel network can be directly obtained after a single sintering process, without the need for subsequent multi-layer ceramic stacking, welding, or mechanical grooving. Compared with traditional planar cold plate or single-layer flow channel ceramic structures, the three-dimensional flow channel structure of this embodiment greatly improves the space utilization and design freedom of the internal flow channels.

[0083] Example 5 Figure 5 This is a cross-sectional schematic diagram of an "S-shaped" sacrificial template 60 and its ceramic substrate in one embodiment of this application.

[0084] This embodiment uses the sacrificial template 60 as its core. By introducing a pre-placed three-dimensional template structure during the ceramic forming stage, the ceramic substrate 10 forms a corresponding S-shaped internal flow channel after sintering, achieving the integral molding of the liquid cooling channel 201 with the ceramic, which has a complex spatial morphology. This embodiment fully demonstrates the technical advantages of this application in terms of flow channel design freedom, ceramic forming capability, and scalability of the liquid cooling structure.

[0085] like Figure 5 As shown, an S-shaped flow channel 201 is prefabricated in the ceramic matrix 10. This flow channel is formed in situ by a sacrificial template 60 embedded in the ceramic green body. The sacrificial template 60 can be placed in the mold along a specific path. After processes such as slurry casting, curing, debinding, and sintering, the template is completely removed, and the space it occupies is ultimately transformed into a hollow S-shaped liquid cooling channel 201 inside the ceramic. This flow channel has a tortuous serpentine structure in the planar direction, which can be used to achieve complex fluid path control and local heat transfer enhancement.

[0086] In this embodiment, the sacrificial template 60 can be made of various materials, and the material selection must combine easy removal, sufficient forming strength, chemical inertness to the ceramic slurry, and processability. Materials that can be used for the sacrificial template 60 include, but are not limited to, paraffin wax, polylactic acid (PLA), polymethyl methacrylate (PMMA), polystyrene (PS), photosensitive resin, and other organic materials that can be removed by melting, decomposition, dissolution, or vaporization. Preferably, the sacrificial template 60 is made of a material with a low melting point or a thermal decomposition temperature lower than the decomposition temperature of the organic components in the ceramic green body, so that it can be easily removed during the drying, degreasing, or pre-sintering stages of the ceramic green body, and to avoid the accumulation of internal stress caused by rapid vaporization.

[0087] The shape of the sacrificial template 60 can be flexibly changed according to design requirements, not only for, but also for Figure 5 The S-shaped structure shown can also be linear, serpentine, loop-shaped, ring-shaped, dendritic, grid-shaped, multi-layered staggered structures, or even a completely three-dimensional spiral structure. The cross-sectional shape of the template can be circular, square, rectangular, trapezoidal, or irregularly shaped with specific functional textures. By pre-setting templates of different shapes, a point-like, line-like, surface-like, or even three-dimensional liquid cooling channel network can be formed within the ceramic body, thereby meeting different heat dissipation requirements, such as localized enhanced heat transfer, overall temperature uniformity, double-sided cooling, or zoned cooling.

[0088] The sacrificial template 60 needs to possess good geometric stability and dimensional accuracy to ensure that it does not undergo significant deformation or floating before the ceramic green body gels, and that its shape remains stable before sintering. Therefore, this application requires that the material of the sacrificial template 60 and the ceramic composite slurry have good chemical inertness and should not swell, soften, or undergo interfacial reactions to avoid affecting the dimensional accuracy of the flow channels. In some embodiments, an inert release agent or film, such as a waxy release layer or a polymer release layer, can be sprayed onto the template surface to further prevent chemical interactions between the template and the slurry, thereby improving the accuracy and consistency of the flow channel formation.

[0089] Regarding template removal methods, various approaches can be employed based on the decomposition characteristics of the template material and the organic components in the ceramic green body, including melt drainage, solvent dissolution, low-temperature vacuum removal, thermal decomposition, and gasification extraction. If the template is made of paraffin wax, it can be melted at 70℃~80℃ and discharged through a pre-reserved drainage channel. If the template is made of PLA or PMMA, it can decompose and volatilize along with the organic components in the ceramic green body during the degreasing stage, ultimately forming an inner cavity. To ensure the smooth discharge of template residue, this application can provide auxiliary venting holes or temporary connecting holes on the outer periphery or non-functional areas of the ceramic green body. These holes can be removed or sealed by machining after sintering.

[0090] The sacrificial template 60 can not only be used to form basic flow channels, but also integrate a variety of functional structures. For example, the template can be designed with a geometry at its end that corresponds to the interface of the liquid cooling channel 201, so that the sintered ceramic naturally forms interface pre-grooves, connecting sections or positioning pillars at the channel inlet or outlet; the template surface can also have textures, ribs, protrusions or rough structures, so that the inner wall of the formed flow channel has the corresponding turbulence function, improves the turbulence of the coolant in the flow channel, and thus improves the heat transfer coefficient.

[0091] When designing the sacrificial template 60, the influence of subsequent sintering shrinkage should be considered, and a certain compensation dimension should be reserved so that the final flow channel maintains the geometric dimensions required by the design after degreasing and sintering.

[0092] Example 6 Figure 6This is a cross-sectional schematic diagram of a "U-shaped" sacrificial template 60 and its ceramic substrate in one embodiment of this application.

[0093] This embodiment employs a sacrificial template 60 with a U-shaped (or U-shaped) reversible structure to construct a liquid cooling channel 201 with reflux characteristics within the ceramic substrate 10. This allows the coolant to form a localized reciprocating flow path in a specific area, thereby enhancing the heat transfer effect in that area. This embodiment demonstrates typical applications of this application in localized enhanced cooling, regional temperature control, and programmable design of flow channels within ceramic substrates.

[0094] Example 7 Figure 7 This is a cross-sectional schematic diagram of a "cylindrical turbulence type" sacrificial template 60 and its ceramic substrate in one embodiment of this application.

[0095] In this embodiment, a sacrificial template 60 with cylindrical through holes is used to form a liquid cooling channel 201 with a periodic turbulent cylindrical array inside the ceramic substrate 10. This changes the flow state of the coolant inside the channel from a stable flow mode that is biased towards laminar flow to an enhanced convection mode with obvious lateral disturbances and local vortex distribution, thereby significantly improving the heat exchange capacity between the fluid and the ceramic wall.

[0096] like Figure 7 As shown, the sacrificial template 60 in this embodiment is entirely covered with cylindrical through holes, which are placed in the target area during the ceramic forming stage. The sacrificial template 60 can be cylindrical through holes, rectangular through holes, triangular through holes, or other irregular through holes, depending on the design requirements. After slurry casting, gel curing, drying, degreasing, and sintering, the sacrificial template 60 is completely removed, and the position it originally occupied forms a three-dimensional structure inside the ceramic substrate, which is equivalent to forming a periodic, high-precision turbulence column array 202 inside the liquid cooling channel 201. These turbulence columns 202 can be arranged at a specific pitch in the channel cross-sectional direction or the channel length direction to form a regular or semi-regular arrangement structure, so that when the fluid flows through, it generates transverse shear, local backflow zone, small-scale eddies, and shuttle flow effect.

[0097] Example 8 Figure 8 This is a cross-sectional schematic diagram of a "branch-type" sacrificial template 60 and its ceramic substrate in one embodiment of this application.

[0098] This embodiment employs a sacrificial template 60 with a combination of a main channel and multiple branch channels to construct a liquid cooling channel 201 structure within the ceramic substrate 10, enabling diversion, partitioning, and controllable flow distribution. By rationally coordinating the geometric layout, cross-sectional dimensions, and pressure drop relationship between the main channel and branch channels, the coolant can actively flow towards the target area, thereby significantly improving the heat exchange efficiency of specific local areas.

[0099] like Figure 8 As shown, the liquid cooling channel 201 consists of a main channel and at least one branch channel. The branch channel can be a straight line, an arc, an S-shape, or a three-dimensional staggered structure, and its shape can be flexibly set according to the location of the target heat dissipation area. This application can actively control the liquid flow rate relationship between the main channel and the branch channel by adjusting the geometry and cross-sectional dimensions of the sacrificial template 60, thereby enhancing the heat dissipation effect in a specific area.

[0100] Example 9 Figure 9 This is a cross-sectional schematic diagram of a "three-dimensional branch type" sacrificial template 60 and its ceramic substrate in one embodiment of this application.

[0101] This embodiment is Figure 4 The structural diagram and cross-sectional diagram of the sacrificial template 60 corresponding to the "double-sided cooling" ceramic substrate show that by arranging three-dimensional branch channels with upper and lower layers linked inside the ceramic, the functional layer areas on the upper and lower sides of the same ceramic substrate can be cooled separately and synergistically. This is an important manifestation of the construction of three-dimensional cooling network in this application.

[0102] Example 10 Figure 10 This is a cross-sectional schematic diagram of a "three-dimensional spiral" sacrificial template 60 and its ceramic substrate in one embodiment of this application.

[0103] This embodiment utilizes a sacrificial template 60 with a spatial spiral structure to form a liquid cooling channel 201 extending along a three-dimensional spiral path within the ceramic substrate 10, thus fully verifying the high degree of design freedom in the internal flow channel morphology and manufacturing method of this application. The three-dimensional spiral flow channel, as a typical representative of complex spatial curves, is a structure difficult to achieve through traditional machining, layered welding, or metal encapsulation. This application, through the sacrificial template 60 forming technology, can completely construct this type of high-degree-of-freedom flow channel inside the ceramic, which is one of the innovations of this invention.

[0104] like Figure 10 As shown, the sacrificial template 60 is a three-dimensional spiral that rises (or falls) layer by layer along the thickness direction of the ceramic substrate 10, while simultaneously exhibiting a circular, elliptical, or arbitrary closed curve layout in the planar direction. The sacrificial template 60 can be designed as a single spiral, multiple spirals in parallel, bidirectional spiral, variable pitch spiral, or a composite spiral structure with different diameter gradient characteristics, depending on the cooling requirements.

[0105] Example 11 Figure 11 This is a cross-sectional schematic diagram of a "three-dimensional upper and lower heat exchange type" sacrificial template 60 and its ceramic substrate in one embodiment of this application.

[0106] This embodiment is Figure 3 The schematic diagram of the sacrificial template 60 corresponding to the "heat spreader 405 type" ceramic substrate shows that by pre-setting a three-dimensional sacrificial template 60 with a height difference between the upper and lower layers, a vertical connecting section and a folding section during the ceramic forming stage, a three-dimensional heat exchange flow channel structure of "heat absorption close to the chip side and heat dissipation close to the heat spreader 405 side" is realized inside the ceramic.

[0107] Example 12 Figure 12 This is a cross-sectional schematic diagram of a "curved" sacrificial template 60 and its liquid-cooled integrated irregular ceramic substrate in one embodiment of this application.

[0108] This embodiment corresponds to Figure 2 The curved irregular ceramic structure shown can achieve liquid cooling channels 201 that are difficult to obtain by traditional ceramic processing methods, such as high curvature surfaces, irregular geometric shapes, and three-dimensional complex structures, by pre-setting a sacrificial template 60 with a curved trajectory and spatial bending path during the ceramic forming stage, so that the ceramic matrix 10 forms a curved internal flow channel with the same shape after sintering.

[0109] This embodiment achieves a high degree of coupling between the curved ceramic outer surface structure and the internal curved liquid cooling channel. For electronic applications requiring bonding to motor housings, cylindrical housings, curved power module base plates, or arc-shaped structures, the curved liquid-cooled ceramic substrate of this embodiment can achieve bonding cooling within a limited space, allowing the coolant to approach the actual heat-generating area along the curvature direction, which is significantly superior to traditional flat-plate cooling solutions. Furthermore, by locally setting an insulating island 301 structure (corresponding to...) on the curved substrate... Figure 2 (Example) A locally flat area can be created on the curved surface for mounting power chips, sensors or ceramic capacitors that are traditionally packaged in planar form, making the arrangement of curved electronic modules more flexible.

[0110] Example 13 Figure 13 This is a schematic diagram of the process flow for preparing a ceramic substrate using an aqueous gel casting method according to one embodiment of this application.

[0111] Step 701. Preparation of composite slurry In this embodiment, zirconia-reinforced alumina ceramic powder is selected as the solid-phase particle system. Through a reasonable proportioning, zirconia plays a role in toughening and improving thermal shock resistance within the alumina matrix. Deionized water is used as the dispersion medium, and appropriate amounts of dispersant, monomer, and crosslinking agent are added. Under stirring conditions, the powder is uniformly dispersed in the aqueous phase to form a highly fluid aqueous composite slurry. Subsequently, vacuum degassing removes air bubbles, ensuring that the slurry can fill the small spaces around the mold and sacrificial template 60 during the subsequent molding stage, thereby guaranteeing the integrity and dimensional accuracy of the final ceramic internal flow channel profile. The aqueous composite slurry system has advantages such as environmental friendliness, low cost, and good system stability, making it suitable for the mass production of large-size, multi-channel, complex-structured ceramics. Step 702. Preparation of sacrificial template 60 In this embodiment, the sacrificial template 60 is made of paraffin wax. Paraffin wax has the characteristics of low melting point, good fluidity, easy molding, and sufficient mechanical strength within a certain temperature range, making it suitable as a flow channel occupant structure in a water-based gel injection molding system. Based on the required planar layout, cross-sectional shape, and connection method to the interface of the liquid cooling channel 201, the paraffin wax is processed into a straight, loop, S-shaped, or multi-branched template using injection molding, casting, machining, or simple molding methods. If necessary, extension sections or positioning sections corresponding to the liquid cooling interface position can be prefabricated at one or more ends of the template. The outer contour of the paraffin wax template directly determines the geometry of the hollow channel inside the ceramic after sintering, and is a key component in the forming of the integrated liquid-cooled structure.

[0112] Step 703. Mold Arrangement The prepared paraffin sacrificial template 60 is assembled into the cavity of the molding mold, which can be a metal mold, resin mold, or ceramic mold. By setting positioning pillars, limiting grooves, support ribs, or clamping structures inside the mold, the spatial position and orientation of the paraffin template within the mold are precisely defined, preventing it from moving or floating during subsequent slurry injection and gelation stages. The relative positional relationship between the mold and the template determines the spatial relationship between the ceramic outline and the internal flow channels. If necessary, a release agent can be sprayed into the mold cavity to facilitate subsequent demolding operations.

[0113] Step 704. Grouting The aqueous composite slurry prepared in step 701 is injected into the mold cavity, allowing the slurry to gradually fill the entire cavity and coat the paraffin template under gravity or appropriate pressure. It is preferable to inject the slurry gradually from bottom to top to reduce air bubble entrainment and ensure that all tiny gaps within the mold are completely wetted by the slurry. Appropriate vibration or slight vacuuming can further promote slurry flow and venting, improving the density of the green body and the quality of the internal cavity forming. After slurry injection, a "ceramic slurry-paraffin template" composite is formed inside the mold.

[0114] Step 705. Gel Curing By controlling the system temperature or initiating a chemical initiation system, the monomers and crosslinking agents in the aqueous slurry undergo a polymerization reaction, forming a three-dimensional network of polymeric gel framework. This framework fixes the ceramic powder in situ, resulting in a gel preform with a certain strength and overall shape. During this process, the paraffin template retains its original shape, serving as a occupant for the internal flow channels. The gel solidification process avoids the problem of relying on complete drying to maintain the preform strength in traditional slip casting, which is beneficial for maintaining the shape stability of complex flow channel structures and thin-walled areas, and reduces the risk of deformation due to uneven shrinkage. Step 706. Drying The demolded gel preform is slowly dried under controlled temperature and humidity conditions to gradually remove moisture, allowing the preform to further solidify and strengthen. After drying, the preform possesses sufficient mechanical strength to proceed to subsequent high-temperature processes such as template removal, degreasing, and sintering.

[0115] Step 707. Remove the sacrificial template 60 In this embodiment, the sacrificial template 60 is paraffin wax, therefore a paraffin wax template removal process is used in step 707. Typically, the dried green body is gradually heated to a temperature range above the melting point of paraffin wax (e.g., 70°C~80°C), causing the paraffin wax to melt and slowly flow out of the green body through pre-designed drainage channels, wax removal holes, or auxiliary channels opened on the outer periphery. Finally, after the paraffin wax is completely removed, a hollow flow channel with the same shape as the template is formed inside the ceramic green body. Since the temperature at this stage is much lower than the ceramic sintering temperature, the green body still exists in a "green" state. Therefore, the heating and wax removal process needs to control the heating rate and the system support method to prevent local support failure or green body deformation due to paraffin wax flow. By rationally designing the wax removal path and template size, the stable formation of the internal flow channel structure can be ensured.

[0116] Step 708. Degreasing The main purpose of degreasing is to further remove residual organic components from the slurry, including dispersants, monomers, crosslinking agents, and some organic binders, while also removing any small-molecule decomposition products that may remain on the paraffin template. The green body is slowly heated in the degreasing furnace according to a pre-set multi-step heating curve, maintaining appropriate holding times within different temperature ranges to ensure the gradual decomposition of organic components and their discharge through gas channels, preventing the formation of high-pressure gas accumulation that could cause the green body to crack. During this process, the internal hollow flow channel, serving as one of the gas emission channels, also facilitates the smooth escape of decomposition products.

[0117] Step 709. Sintering The degreased ceramic green body is heated to the sintering temperature under a suitable atmosphere and temperature, causing the zirconia-reinforced alumina powder to undergo dense sintering, forming an integrated ceramic substrate with high strength, high thermal conductivity, and high insulation properties. During sintering, the green body undergoes isotropic or near-isotropic shrinkage, and the cross-sectional dimensions of the hollow flow channels also decrease proportionally, but the overall geometric relationship remains unchanged. By rationally controlling the sintering regime, a liquid cooling channel 201 structure with dense, smooth inner walls and no obvious blockage can be obtained.

[0118] Step 710. Machining Depending on the application requirements, the sintered ceramic substrate undergoes finishing processes such as shape machining, thickness trimming, drilling of liquid flow channel interface holes and mounting holes 102, and partial chamfering to ensure that the dimensional accuracy, fit accuracy, and installation adaptability of the ceramic substrate meet the design requirements. If necessary, the inlet and outlet areas of the flow channel can also be appropriately trimmed to facilitate connection with metal joints or seals.

[0119] Step 711. Surface Metallization Depending on the specific circuit design and packaging form, copper-clad 401 layers or other metal conductive layers are prepared on one or more surfaces of the ceramic substrate using processes such as DPC, DBC, AMB, thick film printing, sputtering + electroplating, etc. Functional structures such as pads, circuit patterns, and grounding shielding layers are formed through photolithography, laser, or mask printing. The surface-metallized liquid-cooled ceramic substrate can serve as both a power device mounting substrate and a circuit carrier, realizing an electro-thermal integrated design.

[0120] Step 712. Quality Inspection A comprehensive quality inspection is performed on the prepared ceramic substrate. The inspection may include dimensional inspection, flow channel unobstructedness check, flow channel air tightness test, insulation withstand voltage test, metallization adhesion test, and necessary thermal shock or thermal cycling reliability assessment.

[0121] In conclusion, Figure 13 The embodiment shown achieves the integrated fabrication of liquid cooling channel 201 and ceramic substrate through a gel casting process combining water-based composite slurry and paraffin sacrificial template 60. The process is coherent and the key control points are clear, making it suitable for the engineering application and mass production of complex internal flow channels and highly integrated liquid-cooled ceramic substrates.

[0122] Example 14 Figure 14 This is a schematic diagram of the process flow for preparing a ceramic substrate using an organic gel casting method according to one embodiment of this application.

[0123] 801. Preparation of Composite Slurry In this embodiment, aluminum nitride ceramic powder is selected as the solid-phase particle system. Aluminum nitride has high thermal conductivity, low dielectric constant, and good insulation properties, making it suitable for heat dissipation ceramic substrates in high-power electronic devices. Since aluminum nitride powder readily reacts with water to generate ammonia and hydroxides, this embodiment uses anhydrous organic solvents such as anhydrous ethanol and isopropanol as the slurry dispersion medium, allowing the aluminum nitride to remain stable in a completely anhydrous environment. Appropriate amounts of organic dispersant, polymerizable monomer, and crosslinking agent are added to the slurry, and through high-speed stirring and vacuum degassing, a uniform, highly fluid organic composite slurry is obtained, providing a foundation for subsequent gel casting.

[0124] 802. Preparation of Sacrificial Template 60 This embodiment uses high-precision 3D printing to prepare a three-dimensional rigid resin sacrificial template 60. Figure 13 Unlike paraffin wax templates, resin templates offer higher shape accuracy, dimensional stability, and spatial structure realization capabilities, making them particularly suitable for fabricating complex flow channel structures such as three-dimensional interlaced channels, irregularly shaped channels, spiral channels, inclined channels, or multi-layered staggered channels. The template's geometry is designed and generated entirely according to the target flow channel design within the ceramic. Interface areas, tapering areas, turbulence structures 202, and multi-segment connection structures can be pre-set. Through additive manufacturing technology, it is constructed layer by layer to ultimately form a three-dimensional spatial template. The template material must preferentially decompose during the debinding stage, and its thermal decomposition temperature should be lower than the decomposition temperature of the organic binder system in the aluminum nitride blank to ensure smooth drainage within complex flow channel structures and prevent pressure buildup inside the blank.

[0125] 803. Mold Layout Since this embodiment prepares an irregularly shaped ceramic substrate, the mold itself must be designed as an irregular cavity according to the final shape of the ceramic. For example, it can be a curved structure, a ring structure, a stepped structure, a spatial zigzag structure, etc. A three-dimensional rigid resin template is placed inside the irregularly shaped mold, and its position is locked by a precision positioning structure, limiting groove, or snap-on support, ensuring the template remains stable and does not shift during the grouting and curing stages. Because the rigid resin template has high rigidity at room temperature, it can maintain shape integrity in complex spaces, ensuring accurate replication of the final geometric contour of the flow channel.

[0126] 804. Grouting The organic composite slurry prepared in step 801 is injected into the mold, ensuring that the slurry fully fills all the forming space outside the template. Since both the template and the mold have complex shapes, this embodiment typically uses a bottom-up injection method, combined with slight vibration or auxiliary vacuuming, to help the slurry expel gas and fill small spaces, preventing internal defects or flow channel blockage after sintering caused by trapped air bubbles.

[0127] 805. Gel Curing By heating, the monomers and crosslinking agents in the slurry undergo a polymerization reaction to form a three-dimensional network polymer framework, thereby solidifying the aluminum nitride powder in its original position and obtaining an organic gel preform with sufficient mechanical strength. During this stage, the resin template retains its shape, providing geometric support for the internal flow channel structure of the preform.

[0128] 806. Drying During the drying stage, some of the solvent and volatile components in the organic gel preform are gradually removed, allowing the preform to further solidify, shrink, and enhance its mechanical properties. Unlike aqueous forming, the organic system produces a preform with higher strength after drying, exhibiting better overall bonding strength and surface density, and can withstand certain machining processes.

[0129] 807. Machining In this embodiment, the dried green body can be directly machined in step 807. Since the green body has not yet been sintered, its hardness is lower than that of the final ceramic, but its strength is sufficient to support conventional machining operations. Necessary pre-processing can be performed on the green body, including shape finishing, surface smoothing, pre-machining of mounting holes 102, or pre-fabrication of local notches. This method significantly reduces tool wear and processing difficulty compared to post-sintering machining, but the impact of subsequent sintering shrinkage on dimensions must be considered. Final dimensional accuracy is achieved by reserving shrinkage compensation.

[0130] 808. Defatting During the degreasing stage, the heating rate must be strictly controlled to ensure the preferential decomposition and discharge of the resin template. In the multi-stage heating process, the template material gradually decomposes within its specific decomposition temperature range, and the vaporization products are discharged from the green body through a pre-designed exhaust path and flow channel space, forming a complete three-dimensional flow channel structure inside. After the template is completely removed, the temperature continues to rise to decompose residual components such as organic dispersants and binders in the slurry system, preparing for final sintering.

[0131] 809. Sintering The degreased green body is placed in a high-temperature sintering furnace and sintered at high temperature in an inert atmosphere (such as nitrogen or argon). This causes the aluminum nitride powder to undergo particle diffusion, neck growth, and densification processes, ultimately forming an integrated ceramic substrate with high thermal conductivity, high insulation, and high strength. During this stage, the shape, size, and position of the internal three-dimensional flow channels remain consistent with the formed structure and shrink proportionally with sintering shrinkage, forming smooth, dense, and interconnected liquid cooling channels 201.

[0132] 810. Surface metallization Depending on the application requirements, a functional layer can be prepared on the outer surface of the ceramic substrate. Metallization processes such as AMB (Active Metal Brazing 403), DBC (Direct Copper Bonding), or DPC (Laser Activated Copper Plating) can be used to form copper layers, circuit patterns, and pad structures for mounting power devices and signal devices, thereby achieving electro-thermal integrated packaging capabilities.

[0133] 811. Welding heat spreader 405 To further enhance the bottom heat dissipation capacity, this embodiment uses a copper plate as the heat spreader 405, which is welded using a reliable connection method suitable for aluminum nitride ceramics and copper. Preferably, an active metal brazing process 403 is used, allowing the brazing filler metal containing titanium active elements to form a metallurgical bond with the ceramic bottom surface at high temperature, while simultaneously achieving a metal bond between the copper plate and the brazing filler metal. This process can form a reliable ceramic-metal interface, ensuring a tight bond between the heat spreader 405 and the ceramic substrate, significantly improving heat diffusion and thermal management capabilities.

[0134] 812. Quality Inspection Multiple quality tests are performed on the prepared ceramic substrate, including dimensional inspection, internal flow channel connectivity inspection, airtightness test, insulation withstand voltage test, copper cladding 401 adhesion test, heat spreader 405 welding quality inspection, and necessary thermal cycling and thermal shock reliability tests, to ensure that the product's performance indicators meet the design requirements.

[0135] In conclusion, Figure 14 The organic gel casting method shown in this application enables the integrated fabrication of complex three-dimensional liquid cooling channels 201, irregular ceramic structures, and high-performance heat dissipation components through the excellent forming stability of the organic system, the spatial complexity of the 3D printing template, the integrated shaping capability of irregular molds, and the dimensional controllability of machining before sintering.

[0136] Example 15 Figure 15 This is a schematic diagram of the process flow of a method for preparing a ceramic substrate according to one embodiment of this application.

[0137] 901. Preparation of slurry containing ceramic powder In this embodiment, a slurry containing ceramic powder is prepared for subsequent grouting operations. When preparing the slurry containing ceramic powder, the ceramic powder is dispersed in a liquid phase to obtain a suspension with a solid content of 50 to 70% by volume. The liquid phase contains monomers, crosslinking agents, dispersants, and an initiation system. Preferably, the liquid phase is deionized water, and the dispersant is an anionic dispersant, preferably ammonium polyacrylate. Alternatively, the liquid phase is a non-aqueous solvent selected from anhydrous ethanol, isopropanol, and mixtures thereof, and the dispersant is a phosphate ester or polyether-modified non-aqueous dispersant. Preferably, the monomer is an acrylic monomer or an acrylamide monomer, and the crosslinking agent is a diacrylate crosslinking agent. Preferably, the initiation system is a redox / thermal initiation combination, preferably ammonium persulfate / tetramethylethylenediamine or benzoyl peroxide / tertiary amine, and preferably achieves a controllable gel time of 5 to 20 minutes at 25 to 35 degrees Celsius.

[0138] 902. Preparation of Sacrificial Templates This embodiment prepares a sacrificial template that matches the shape of the target liquid channel. The sacrificial template is a planar structure template, prepared by injection molding, compression molding, or extrusion; or, the sacrificial template is a three-dimensional structure template, prepared by three-dimensional printing technology, multi-segment splicing, or combination molding; or, the sacrificial template is made of a controllable thermoplastic or thermosetting material, preferably paraffin wax, polylactic acid, polymethyl methacrylate, polystyrene, or photosensitive resin; or, the surface of the sacrificial template is provided with textures or grooves, thereby forming corresponding textures or grooves in the liquid channel.

[0139] 903. Grouting A sacrificial template is fixed inside a mold, and slurry is poured in to cover the sacrificial template and fill the mold, resulting in a ceramic preform. The mold cavity can be designed according to the shape of the target ceramic substrate. A bottom-up pouring method is typically used, combined with slight vibration or auxiliary vacuuming to help the slurry expel gas, fill small spaces, and prevent internal defects or flow channel blockage caused by trapped air bubbles after sintering. After pouring, gel curing and drying steps can be performed to obtain a ceramic preform with a certain strength.

[0140] 904. Remove the sacrifice template The sacrificial template is removed to form a hollow channel within the ceramic body.

[0141] The sacrificial template can be partially or completely removed during the drying of the ceramic body; preferably, during the removal of the sacrificial template, vent holes or connecting holes are provided on the outer periphery or non-functional areas of the ceramic body to facilitate the discharge of the sacrificial template material.

[0142] Alternatively, the sacrificial template can be removed by degreasing, and the ceramic body can be placed in a degreasing atmosphere to remove organic components from the sacrificial template and slurry; preferably, the degreasing atmosphere can be air, inert gas or reducing atmosphere; preferably, a multi-step heating and heat preservation method is used during the degreasing process; preferably, during the degreasing process, vent holes or connecting holes are provided on the outer periphery or non-functional area of ​​the ceramic body to promote the discharge of organic components from the sacrificial template material and slurry.

[0143] 905. Sintering Sintering transforms the hollow channels within the ceramic preform into liquid channels, thus forming a ceramic substrate. As demonstrated by the above embodiments, the ceramic substrate of this application exhibits significant and highly unified technical advantages in terms of structural morphology, process system, and future packaging adaptability. By introducing a sacrificial template 60 during the ceramic forming stage, the internal liquid cooling channel 201 is constructed in situ during synchronous sintering with the ceramic, completely eliminating interface risks associated with traditional post-processing techniques such as grooving and welding. This results in a highly airtight, highly insulating, highly reliable, and extremely low thermal resistance integral ceramic cooling structure. Furthermore, this application allows for the free configuration of the sacrificial template 60, enabling the simultaneous integral forming of three-dimensional flow channels, upper and lower heat exchange channels, complex turbulence structures 202, and various irregularly shaped ceramic forms. This allows the cooling network to overcome planar limitations and be flexibly customized according to the needs of the heat-generating area, combining structural freedom with enhanced heat dissipation capabilities—something difficult to achieve in traditional ceramic or metal processing systems. Meanwhile, the ceramic substrate obtained in this application is fully compatible with existing mature metallization and packaging technologies such as DPC, DBC, and AMB. It can be used for planar packaging as well as curved and double-sided packaging, enabling it to be directly integrated into the existing power module manufacturing system and play an important foundational supporting role in the future trend of higher integration, higher power density, and smaller electro-thermal integrated packaging.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ceramic substrate, comprising a ceramic matrix and a liquid channel layer, characterized in that, The liquid channel layer is disposed inside the ceramic substrate and integrally sintered with the ceramic substrate. The liquid channel layer includes liquid channels for containing cooling medium and extends along a three-dimensional spatial path inside the ceramic substrate.

2. The ceramic substrate according to claim 1, characterized in that, The three-dimensional spatial path includes any one or any combination of straight, serpentine, loop, circular, tree-like, grid-like, multi-layered, three-dimensional serpentine, multi-layered misaligned structure, spiral, and fully three-dimensional spiral structure; or, the three-dimensional spatial path includes at least two paths whose axes are not coplanar. Alternatively, the liquid channel is prefabricated in situ during the preform forming stage of the ceramic matrix using a sacrificial template, and then formed after removing the sacrificial template and sintering. Alternatively, the liquid channel may include at least one main channel, or may further include at least one branch channel and a confluence area or outlet channel; preferably, the main channel or confluence area is provided with a flow disturbance structure; Alternatively, the cross-section of the liquid channel may be rectangular, trapezoidal, annular, circular, polygonal, or any combination of the above shapes.

3. The ceramic substrate according to claim 1 or 2, characterized in that, The ceramic matrix is ​​a planar block structure with all surfaces being flat; Alternatively, the ceramic substrate may be at least one curved block structure with a curved surface, wherein the curved surface has unidirectional curvature or bidirectional curvature. Alternatively, the ceramic substrate is a bent plate structure, which is a single-segment or multi-segment planar bending shape or a multi-segment spatial bending shape. Alternatively, the ceramic matrix may be a ring-shaped, arc-shaped, fan-shaped, ring-belt-shaped, ring-step-shaped, or hollow cylindrical structure.

4. A method for preparing a ceramic substrate, characterized in that, include: Preparation of a slurry containing ceramic powder; Prepare a sacrificial template that matches the shape of the target liquid channel; A sacrificial template is fixed inside a mold, and slurry is poured in to cover the sacrificial template and fill the mold, thus obtaining a ceramic body. Remove the sacrificial template to form a hollow channel within the ceramic body; Sintering transforms the hollow channels within the ceramic blank into liquid channels, thus forming a ceramic substrate from the ceramic blank.

5. The method for preparing a ceramic substrate according to claim 4, characterized in that, The sacrificial template is a planar structure template, prepared by injection molding, compression molding or extrusion; Alternatively, the sacrificial template is a three-dimensional structure template, which is prepared by three-dimensional printing technology, multi-segment splicing or combination molding; Alternatively, the sacrificial template may be made of a controllable thermoplastic or thermosetting material, preferably paraffin wax, polylactic acid, polymethyl methacrylate, polystyrene or photosensitive resin; Alternatively, the surface of the sacrificial template may be provided with textures or grooves, thereby forming corresponding textures or grooves within the liquid channel.

6. The method for preparing a ceramic substrate according to claim 4, characterized in that, When preparing a slurry containing ceramic powder, the ceramic powder is dispersed in a liquid phase to obtain a suspension with a solid content of 50 to 70% by volume. The liquid phase contains monomers, crosslinking agents, dispersants and initiation systems. Preferably, the liquid phase is deionized water, and the dispersant is an anionic dispersant, preferably ammonium polyacrylate; or, the liquid phase is a non-aqueous solvent selected from anhydrous ethanol, isopropanol and mixtures thereof, and the dispersant is a phosphate ester or polyether modified non-aqueous dispersant. Preferably, the monomer is an acrylic monomer or an acrylamide monomer, and the crosslinking agent is a diacrylate crosslinking agent; Preferably, the initiation system is a redox / thermal initiation combination, preferably ammonium persulfate / tetramethylethylenediamine or benzoyl peroxide / tertiary amine, and preferably achieves a controllable gel time of 5 to 20 minutes at 25 to 35 degrees Celsius.

7. The method for preparing a ceramic substrate according to claim 6, characterized in that, It also includes a gel solidification step: at room temperature or slightly elevated temperature, the slurry is volumetrically gelled in the mold by redox initiation and / or thermal initiation to obtain a ceramic green body with self-supporting strength.

8. The method for preparing a ceramic substrate according to claim 4, characterized in that, After obtaining the ceramic blank, post-processing of the blank is carried out, including drying the ceramic blank; Alternatively, it may include: at least partially removing the sacrificial template; preferably, during the removal of the sacrificial template, venting holes or connecting holes are provided on the periphery of the ceramic blank or in a non-functional area to facilitate the discharge of material from the sacrificial template; Alternatively, it may include: machining the ceramic body to obtain predetermined dimensional accuracy, surface roughness, surface microstructure, or through-hole structure.

9. The method for preparing a ceramic substrate according to claim 4, characterized in that, When removing the sacrificial template, the ceramic body is placed in a degreasing atmosphere for degreasing treatment to remove the organic components in the sacrificial template and slurry; Preferably, the degreasing atmosphere can be air, an inert gas, or a reducing atmosphere; Preferably, a multi-stage heating and heat preservation method is used during the degreasing process; Preferably, during the degreasing process, venting holes or connecting holes are provided on the outer periphery or non-functional areas of the ceramic blank to facilitate the discharge of organic components from the material and slurry of the sacrificial template.

10. An electronic device, characterized in that, The electronic device includes components and a liquid cooling circulation system, and also includes a ceramic substrate prepared by the method of preparing the ceramic substrate according to any one of claims 1-3 or according to any one of claims 4-9; The liquid cooling circulation system and the liquid channel of the ceramic substrate are connected, and the liquid cooling circulation system allows the cooling medium to flow in the liquid channel. Preferably, the liquid cooling circulation system includes a pump, a heat exchanger, and liquid piping; Preferably, the cooling medium is water, an aqueous solution of ethylene glycol, a dielectric coolant, or a synthetic oil.

Images