Ceramic substrate and preparation method thereof
By integrating microflow channels and micropumps in the ceramic substrate to drive the cooling medium flow, the problem of insufficient heat dissipation capability of the ceramic substrate on high-thermal design power consumption devices is solved, achieving more efficient heat dissipation and more reliable design.
Patent Information
- Application Number
- CN202311551880.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-20
- Publication Date
- 2025-05-20
AI Technical Summary
When ceramic substrates are equipped with devices with high thermal design power consumption, they can easily lead to an increase in the operating temperature of the device, affecting its performance, reliability and life. The existing heat dissipation designs have problems with space occupation and reliability risks.
A ceramic substrate is designed that contains microflowers and micropumps, which drive the cooling medium in the microflowers to flow without external power supply equipment, enhancing the heat exchange of cooling medium and components.
Effectively reduce the working temperature of components, enhance the heat dissipation ability of ceramic substrates and devices, reduce space occupation, and improve the reliability of heat dissipation.
Smart Images
Figure CN120021011A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor devices, and particularly to a ceramic substrate and a method for preparing the ceramic substrate. Background Art
[0002] Ceramic substrates have become the basic materials for high-power power electronic circuit structure technology and interconnection technology. A ceramic substrate refers to a special process board in which a copper foil is directly bonded to the surface of an alumina or aluminum nitride ceramic substrate at high temperature. The manufactured ultra-thin composite substrate has excellent electrical insulation performance, high thermal conductivity, excellent soft N soldering property, and high adhesion strength, and can be etched into various patterns like a printed circuit board (PCB), and has strong current-carrying capacity.
[0003] Since ceramic substrates have strong current-carrying capacity, they are often used to carry devices with high thermal design power (TDP). However, a high TDP is likely to bring a high device operating temperature, and the operating temperature of the device will affect the performance, reliability, and lifespan of the device. Therefore, it is necessary to perform heat dissipation design on the ceramic substrate to enhance the heat dissipation capacity of the ceramic substrate and the device. Summary of the Invention
[0004] The present application provides a ceramic substrate and a method for preparing the ceramic substrate. The ceramic substrate contains microchannels and a micropump. The micropump drives the cooling medium in the microchannels to flow, and there is no need for external power-providing equipment, which can strengthen the heat exchange between the cooling medium and the components.
[0005] In a first aspect, a ceramic substrate is provided. A microchannel layer and a micropump are provided in the ceramic substrate. The microchannel layer includes at least one microchannel for accommodating a cooling medium. The micropump is communicated with the microchannel of the microchannel layer and is used to drive the flow of the cooling medium.
[0006] The ceramic substrate provided by the present application contains microchannels and a micropump. The micropump drives the cooling medium in the microchannels to flow, and there is no need for external power-providing equipment, which can strengthen the heat exchange between the cooling medium and the components and has strong heat dissipation capacity.
[0007] The microchannel layer includes a microchannel region and a non-microchannel region, and the microchannel region is composed of microchannels.
[0008] The cooling medium can be various flowable liquids or gases, which can be used for heat exchange with the components on the surface of the ceramic substrate to reduce the operating temperature of the components. Exemplarily, the cooling medium can be water, liquid nitrogen, liquid metal, methanol, ethanol, silicone oil, etc.
[0009] This application does not impose any restrictions on the temperature range of the cooling medium. If the function of the microchannel layer is cooling, a cooling medium with a temperature lower than the operating temperature of the components can be used. For example, for a chip device with a TDP of 18 W, using cooling water at -10°C can keep the chip operating temperature below 0°C. If the function of the microchannel layer is to control the temperature of the ceramic substrate and each component, a fluid medium with a temperature higher than the operating temperature of the components can also be used to enable each part of each device to reach the required thermal design temperature.
[0010] Exemplarily, the micropump can be a piezoelectric ceramic pump, which can be located near components such as chips that require key heat dissipation. The generated jet has a high convective heat transfer coefficient, which can take away a large amount of heat from components such as chips, and has strong heat dissipation ability.
[0011] Combined with the first aspect, in some implementation manners of the first aspect, the non-microchannel region of the microchannel layer and the microchannels are staggered in a first direction, the first direction is parallel to the surface of the ceramic substrate, and the non-microchannel region is used to set a conductive structure.
[0012] Exemplarily, the non-microchannel region can be used to set a conductive channel, such as a copper via or other metal traces.
[0013] In the ceramic substrate provided by this application, the non-microchannel region of the microchannel layer and the microchannels are staggered in a direction parallel to the surface of the ceramic substrate. The microchannel layer inside the ceramic substrate does not affect the interconnection trace function of the ceramic substrate, and can improve the heat dissipation efficiency without causing additional space waste.
[0014] Combined with the first aspect, in some implementation manners of the first aspect, it further includes a support layer, which is stacked with the microchannel layer and is used to support the microchannel layer.
[0015] In the ceramic substrate provided by this application, the support layer and the microchannel layer are stacked, which can improve the stability of the ceramic substrate.
[0016] Combined with the first aspect, in some implementation manners of the first aspect, the side of the microchannel layer away from the support layer is used to set components.
[0017] In the ceramic substrate provided by this application, components can be set on one side of the microchannel layer. The distance between the components and the cooling medium is small, which can reduce the thermal resistance, enabling the cooling medium in the microchannels to take away a large amount of heat from components such as chips, and has strong heat dissipation ability.
[0018] Combined with the first aspect, in some implementation manners of the first aspect, the support layer is provided on both sides of the microchannel layer, wherein the support layer on one side of the microchannel layer is used to set components.
[0019] In the ceramic substrate provided by the present application, components can be arranged on one side of the support layer, which can enhance the heat dissipation ability while improving the stability and electrical properties of the ceramic substrate.
[0020] In combination with the first aspect, in some implementation manners of the first aspect, the side of the support layer away from the microchannel layer is used to arrange components.
[0021] In the ceramic substrate provided by the present application, components can be arranged on one side of the support layer, which can enhance the heat dissipation ability while improving the stability of the ceramic substrate.
[0022] In combination with the first aspect, in some implementation manners of the first aspect, the absolute value of the difference between the coefficient of thermal expansion (CTE) of the microchannel layer and the CTE of the support layer is less than a preset threshold.
[0023] In the ceramic substrate provided by the present application, the CTEs of the microchannel layer and the support layer are the same or close, which can reduce the cracking risk caused by thermal stress during heat dissipation due to connection methods such as welding for dissimilar materials. At the same time, the microchannel layer and the support layer can be manufactured using the same ceramic raw material, enabling integrated processing and forming, and improving the manufacturing efficiency of the ceramic substrate.
[0024] In combination with the first aspect, in some implementation manners of the first aspect, the shape of the cross-section of the microchannel parallel to the surface of the ceramic substrate includes any one or more of S-shaped, parallel-connected type, series-parallel combined type, vortex type, cylindrical pin rib type, and groove array type.
[0025] In combination with the first aspect, in some implementation manners of the first aspect, the width or diameter of the microchannel is in the range of 10 micrometers to 10,000 micrometers.
[0026] In combination with the first aspect, in some implementation manners of the first aspect, the microchannel layer includes an inlet and an outlet, and the cooling medium enters the microchannel layer from the inlet and flows out of the microchannel layer from the outlet.
[0027] In the ceramic substrate provided by the present application, the cooling medium enters the microchannel layer from the inlet and flows out of the microchannel layer from the outlet, which can continuously take away heat and improve the heat dissipation efficiency.
[0028] In a second aspect, a method for preparing a ceramic substrate is provided, including: forming a microchannel layer, the microchannel layer including at least one microchannel for accommodating a cooling medium; arranging a micropump in the microchannel layer, the micropump being communicated with the microchannel of the microchannel layer, and the micropump being used to drive the flow of the cooling medium.
[0029] In combination with the second aspect, in certain implementations of the second aspect, the non-microchannel regions of the microchannel layer and the microchannels are alternately distributed in a first direction parallel to the surface of the ceramic substrate, and the non-microchannel regions are used to dispose conductive structures.
[0030] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: forming a support layer, which is stacked with the microchannel layer and is used to support the microchannel layer.
[0031] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: disposing components on a side of the microchannel layer away from the support layer.
[0032] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: disposing components on the support layer on one side of the microchannel layer, wherein the support layer is disposed on both sides of the microchannel layer.
[0033] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: disposing components on a side of the support layer away from the microchannel layer.
[0034] In combination with the second aspect, in certain implementations of the second aspect, the absolute value of the difference between the thermal expansion coefficient of the microchannel layer and the thermal expansion coefficient of the support layer is less than a preset threshold.
[0035] In combination with the second aspect, in certain implementations of the second aspect, the shape of the cross-section of the microchannel parallel to the surface of the ceramic substrate includes any one or more of S-shaped, parallel-connected type, series-parallel-connected type, vortex type, cylindrical pin rib type, and groove array type.
[0036] In combination with the second aspect, in certain implementations of the second aspect, the width or diameter of the microchannel is in the range of 10 micrometers to 10,000 micrometers.
[0037] In combination with the second aspect, in certain implementations of the second aspect, the microchannel layer includes an inlet and an outlet, and the cooling medium enters the microchannel layer from the inlet and flows out of the microchannel layer from the outlet.
[0038] In a third aspect, an electronic device is provided, which includes components and the ceramic substrate described in the first aspect and any implementation of the first aspect, and the components are disposed on the ceramic substrate. Description of the Drawings
[0039] Figure 1 It is a schematic structural diagram of a ceramic substrate provided by an embodiment of the present application.
[0040] Figure 2It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0041] Figure 3 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0042] Figure 4 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0043] Figure 5 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0044] Figure 6 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0045] Figure 7 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0046] Figure 8 It is a schematic diagram of an S-shaped microchannel provided by an embodiment of the present application.
[0047] Figure 9 It is a schematic diagram of a parallel-type microchannel provided by an embodiment of the present application.
[0048] Figure 10 It is a schematic diagram of a series-parallel combined microchannel provided by an embodiment of the present application.
[0049] Figure 11 It is a schematic diagram of a vortex-type microchannel provided by an embodiment of the present application.
[0050] Figure 12 It is a schematic diagram of a cylindrical pin rib-type microchannel provided by an embodiment of the present application.
[0051] Figure 13 It is a schematic diagram of a groove array-type microchannel provided by an embodiment of the present application.
[0052] Figure 14 It is an exemplary flowchart of a method for preparing a ceramic substrate provided by an embodiment of the present application.
[0053] Figure 15 It is an exemplary flowchart of preparing a ceramic substrate by a tape casting method provided by an embodiment of the present application.
[0054] Figure 16 It is an exemplary flowchart of preparing a ceramic substrate by a sintering-welding method provided by an embodiment of the present application. Detailed implementation manners
[0055] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.
[0056] In the embodiments of the present application, words such as "exemplary" and "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" in the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of the word "exemplary" is intended to present concepts in a specific manner.
[0057] The business scenarios described in the embodiments of the present application are for more clearly illustrating the technical solutions in the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Those of ordinary skill in the art can know that with the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are equally applicable to similar technical problems.
[0058] In this specification, references to "one embodiment" or "some embodiments" etc. mean that a specific feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" etc. that appear in different places in this specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.
[0059] In the present application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: including the case where A exists alone, the case where A and B exist simultaneously, and the case where B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (item)" or its similar expression below refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, c can be single or multiple.
[0060] To facilitate the understanding of the embodiments of the present application, some definitions involved in the present application will be briefly described first.
[0061] 1. Coefficient of thermal expansion (CTE): The coefficient that represents the regularity of the change in geometric properties of a substance with temperature under the effect of thermal expansion and contraction.
[0062] 2. Printed circuit board (PCB): A carrier for the electrical interconnection of electronic components.
[0063] 3. Heat flux density: The amount of heat transferred through a unit area. It represents the rate of heat transfer through a specific surface area and is usually measured as the amount of heat passing through a unit area per unit time.
[0064] 4. Convective heat transfer coefficient: In the process of convective heat transfer, it is the ratio of the heat transfer rate per unit area to the temperature difference, used to represent the heat transfer efficiency between a fluid and a solid interface.
[0065] Ceramic substrates have become the basic materials for high-power power electronic circuit structure technology and interconnection technology. A ceramic substrate refers to a special process board where copper foil is directly bonded to the surface of an alumina or aluminum nitride ceramic substrate at high temperature. The resulting ultra-thin composite substrate has excellent electrical insulation properties, high thermal conductivity, excellent soft N soldering performance, and high adhesion strength, and can be etched into various patterns like a printed circuit board (PCB), with strong current-carrying capacity.
[0066] Due to the strong current-carrying capacity of ceramic substrates, they are often used to carry devices with a high thermal design power (TDP). However, a high TDP is likely to lead to a high operating temperature of the device, and the operating temperature of the device will affect the performance, reliability, and lifespan of the device. Therefore, heat dissipation design for the ceramic substrate is required to enhance the heat dissipation capacity of the ceramic substrate and the device.
[0067] Existing conventional heat dissipation methods for ceramic substrates include using additional radiators, heat sinks, or cold plates to dissipate heat from the ceramic substrate. The ceramic substrate and the additional radiator are connected through thermal interface materials (Tim) such as thermal gel or thermal pad, or they are connected by welding.
[0068] Additional heat dissipation devices require installation space and cause an increase in the thickness direction, which is not conducive to simplification and thin-and-light design. Moreover, in many cases, there are other integrated modules near the ceramic substrate, leaving no space for installing a radiator.
[0069] Ceramic substrates are commonly used in the semiconductor manufacturing and testing industries and have requirements for vacuum environments (such as air pressure) and clean environments (such as organic matter partial pressure, etc.). If organic Tims such as thermal conductive gels and thermal pads are used for the connection between the ceramic substrate and the radiator, there are risks of gas entrapment, high outgassing rate, large amount of residual gas, and cavity contamination. If the ceramic substrate is connected to the radiator, heat sink, or cold plate by welding, there is also a reliability risk that different coefficients of thermal expansion (CTE) of different materials may cause interface cracking during temperature changes, requiring additional welding and assembly processes. At the same time, there may be a situation of relatively large thermal resistance in external heat dissipation. For example, a certain chip is installed on a ceramic substrate, the components on the ceramic substrate operate at a relatively high temperature, a water-cooled plate is provided above the ceramic substrate and is connected to the ceramic substrate through a thermal pad, the cooling medium in the water-cooled plate is water with a temperature of -10°C, while the operating temperature of the chip is 40°C, the temperature difference is 50°C, and the thermal resistance between the chip and the cooling medium is relatively large.
[0070] The embodiment of the present application provides a substrate, which can solve the heat dissipation problem of the ceramic substrate and its components, and reduce the operating temperature of the ceramic substrate and its components. At the same time, it also solves the problem in the prior art that the ceramic substrate and the microchannel cold plate need to be additionally welded or connected using Tim materials and cannot be integrally formed.
[0071] Figure 1 It is a schematic structural diagram of a ceramic substrate provided by the embodiment of the present application.
[0072] A microchannel layer 110 and a micropump 130 are provided in the ceramic substrate 100. The microchannel layer 110 includes at least one microchannel 180, and the microchannel is used to accommodate a cooling medium. The micropump 130 is communicated with the microchannel 180 of the microchannel layer 110 and is used to drive the flow of the cooling medium in the microchannel 180.
[0073] The cooling medium can be various flowable liquids or gases, and can be used for heat exchange with the components on the surface of the ceramic substrate to reduce the operating temperature of the components. Exemplarily, the cooling medium can be water, liquid nitrogen, liquid metal, methanol, ethanol, silicone oil, etc.
[0074] Exemplarily, the micropump 130 can be a piezoelectric ceramic pump, which can be located near components such as chips that require key heat dissipation. The generated jet has a relatively high convective heat transfer coefficient, which can take away a large amount of heat from components such as chips, and has strong heat dissipation ability.
[0075] It should be understood thatFigure 1 The shape of the microchannel 180 shown is the cross-section in the direction perpendicular to the surface of the ceramic substrate 100. The shape of the cross-section of the microchannel 180 parallel to the surface of the ceramic substrate 100 can be various irregular shapes, such as S-shaped, parallel-connected type, series-parallel combined type, vortex type, cylindrical pin rib type, groove array type, etc. This example should not be construed as a limitation to this application.
[0076] Figure 2 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of this application.
[0077] The ceramic substrate 200 provided by an embodiment of this application includes a microchannel layer 210, a support layer 220, a micropump 230, a micropump inlet 240, a micropump outlet 250, a metal line 260, components 270, a microchannel 280, a microchannel layer inlet 211, and a microchannel layer outlet 213. Among them, the microchannel layer 210 is the middle layer of the ceramic substrate 200 and is located between the support layers 220. The support layers 220 are arranged on both sides of the microchannel layer 210, and one of the support layers 220 on one side of the microchannel layer 210 is used to arrange the components 270. There is at least one microchannel 280 with a diameter of millimeters or micrometers in the microchannel layer 210. Metal wires are arranged inside the ceramic substrate 200 and are led out on the surface of the ceramic substrate 200 to form the metal line 260. Components 270 such as chips are arranged on the support layer 220 on one side of the microchannel layer 210. The micropump inlet 240 and the micropump outlet 250 are connected to the microchannel 280 in the microchannel layer 210, and the micropump 230 drives the flow of the cooling medium in the microchannel 280, without the need for external power-providing equipment, and the formed ceramic substrate 200 itself is equipped with a cooling function.
[0078] The cooling medium enters the microchannel layer from the microchannel layer inlet 211, and flows out from the microchannel layer outlet 213 after passing through the microchannel 280 in the microchannel layer 210. The micropump 230 drives the cooling medium in the microchannel 280 to flow in and out of the micropump inlet 240 and the micropump outlet 250.
[0079] The cooling medium can be various flowable liquids or gases. This application does not make any limitation on the temperature range of the cooling medium. If the function of the microchannel layer 210 is cooling, a cooling medium with a temperature lower than the working temperature can be used. The thermal resistance of the microchannel layer 210 can be less than 0.1 Kelvin per watt (K / W). For example, for a chip device with a TDP of 18W, using -10°C cooling water can achieve a chip working temperature below 0°C. If the function of the microchannel layer 210 is to control the temperature of the ceramic substrate and each device, a fluid medium with a temperature higher than the working temperature can also be used, so that each part of each device reaches the required thermal design temperature.
[0080] Moreover, a micropump 230, such as a piezoelectric ceramic pump, can be located near components 270 that require key heat dissipation, such as chips. The generated jet flow has a relatively high convective heat transfer coefficient h, which can carry away a large amount of heat Q from devices such as chips, and thus has a strong heat dissipation capacity. Among them, Q = h×AΔt, where A is the heat transfer surface area and Δt is the temperature difference between the microchannel wall surface and the cooling medium.
[0081] The form of the micropump 230 includes but is not limited to piezoelectric ceramic micropumps. Based on the inverse piezoelectric effect, the piezoelectric drive diaphragm vibrates, causing the cavity volume to change. The one-way valve controls the flow direction to generate a directional flow. Among them, the type of the one-way valve can be a passive valve, an active valve or a specific structure valve. The passive valve can be opened and closed by deforming the valve body under the action of the fluid pressure. The active valve is controlled by a driver to open or close the one-way valve. The specific structure valve relies on the characteristics of certain fixed structure flow resistance and direction to achieve an overall one-way flow. The volume of the micropump 230 can be in the range of 0.1 cubic centimeters (cm 3 ) to 1 cm 3 , the thickness can be in the range of 0.3 to 10 millimeters (mm), and the flow rate can be in the range of 0.1 to 500 milliliters per minute (mL / min).
[0082] Exemplarily, the diameter of the microchannel 280 can be set in the range of 10 to 10,000 micrometers. It should be understood that Figure 2 the shape of the microchannel 280 shown is the cross-section in the direction perpendicular to the surface of the ceramic substrate 200. The shape of the cross-section of the microchannel 280 parallel to the surface of the ceramic substrate 200 can be various irregular shapes, such as S-shaped, parallel-connected type, series-parallel combined type, vortex type, cylindrical pin fin type, groove array type, etc. This example should not be construed as a limitation to the present application. The manufacturing materials of the microchannel layer 210 and the support layer 220 can be the same or different, including but not limited to high thermal conductivity ceramics such as alumina, aluminum nitride, and silicon nitride. The CTE of the microchannel layer 210 and the support layer 220 is the same or close, which can reduce the cracking risk caused by thermal stress during heat dissipation due to connection methods such as welding of dissimilar materials.
[0083] The forming method of the ceramic substrate 200 with an internal heat dissipation microchannel provided by the present application can be that during the forming process of the ceramic substrate 200, a space for designing and reserving the microchannel 280 and placing the micropump 230 is designed, and a sacrificial material such as paraffin is laid according to the design. Through high-temperature volatilization, cracking, melting or dissolution, etc., a microchannel layer is formed during the forming process of the ceramic substrate 200.
[0084] Figure 3 is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0085] Figure 3 With Figure 2Correspondingly, in some possible application scenarios, the upper and lower surfaces of the microchannel layer 210 need to be interconnected to meet the design requirements. The microchannel layer 210 includes a microchannel region and a non-microchannel region, and the non-microchannel region and the microchannel region are staggered in the surface direction parallel to the ceramic substrate 200. Compared with Figure 2 In comparison, Figure 3 In the ceramic substrate 200 shown, a conductive structure such as a conductive channel 290 is further provided in the non-microchannel region of the microchannel layer 210. Exemplarily, the conductive channel 290 can be a copper via, and the conductive channel 290 is staggered with the microchannels 280 of the microchannel layer 210, so that the upper and lower surfaces of the microchannel layer 210 are interconnected on both sides.
[0086] It should be understood that the support layer 220 includes a structure in which a dielectric layer and a metal layer are stacked. The shaded part of the support layer 220 in the figure is the metal layer, and the blank part is the dielectric layer. The conductive channel 290 can connect the metal layers on the upper and lower surfaces.
[0087] Figure 4 is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0088] The ceramic substrate 300 provided by an embodiment of the present application includes a microchannel layer 310, a support layer 320, a micropump 330, a micropump inlet 340, a micropump outlet 350, a metal line 360, a component 370, a microchannel 380, a microchannel layer inlet 311, and a microchannel layer outlet 313. Among them, the support layer 320 is stacked with the microchannel layer 310. The support layer 320 can support the microchannel layer 310 and can also be used to provide a conductive structure.
[0089] Among them, the microchannel layer 310 is the middle layer of the ceramic substrate 300 and is located between the support layers 320. There is at least one microchannel 380 with a diameter of millimeters or micrometers in the microchannel layer 310. Metal wires are provided inside the ceramic substrate 300 and are led out on the surface of the ceramic substrate 300 to form a metal line 360. Components 370 such as chips are arranged on the support layer 220 on one side of the microchannel layer 310. The micropump inlet 340 and the micropump outlet 350 are connected to the microchannel 380 of the microchannel layer 310. The micropump 330 drives the flow of the cooling medium in the microchannel 380, and there is no need for external power-providing equipment. The formed ceramic substrate 300 itself is equipped with a cooling function.
[0090] The cooling medium enters the microchannel layer from the microchannel layer inlet 311, passes through the microchannel 380 of the microchannel layer 310, and then flows out from the microchannel layer outlet 313. The micropump 330 drives the cooling medium in the microchannel 380 to flow in and out of the micropump inlet 340 and the micropump outlet 350.
[0091] Optionally, in some possible application scenarios, the upper and lower surfaces of the microchannel layer 310 need to be interconnected to meet the design requirements. The microchannel layer 310 includes a microchannel region and a non-microchannel region, and the non-microchannel region and the microchannel region are staggered in the surface direction parallel to the ceramic substrate 300. Conductive structures such as conductive channels 390 can be provided in the non-microchannel region of the microchannel layer 310. It should be understood that the support layer 320 includes a structure in which a dielectric layer and a metal layer are stacked. The shaded part of the support layer 320 in the figure is the metal layer, and the blank part is the dielectric layer. The conductive channel 390 can connect the metal layers on the upper and lower surfaces. It should be understood that if there is no interconnection requirement between the upper and lower surfaces of the microchannel layer 310, the conductive channel 390 may not be provided in the non-microchannel region of the microchannel layer 310.
[0092] The cooling medium can be various flowable liquids or gases. This application does not impose any limitation on the temperature range of the cooling medium. If the function of the microchannel layer 310 is cooling, a cooling medium with a temperature lower than the operating temperature can be used. The thermal resistance of the microchannel layer 310 can be less than 0.1 Kelvin per watt (K / W). For example, for a chip device with a TDP of 18 W, using -10°C cooling water can achieve a chip operating temperature below 0°C. If the function of the microchannel layer 310 is to control the temperature of the ceramic substrate and each device, a fluid medium with a temperature higher than the operating temperature can also be used to enable each part of each device to reach the required thermal design temperature.
[0093] Moreover, the micropump 330, such as a piezoelectric ceramic pump, can be located near components 370 that require key heat dissipation, such as a chip. The generated jet has a relatively high convective heat transfer coefficient h, which can take away a large amount of heat Q from devices such as the chip, and has strong heat dissipation ability. Among them, Q = h×AΔt, where A is the heat transfer surface area and Δt is the temperature difference between the microchannel wall surface and the cooling medium.
[0094] The form of the micropump 330 includes but is not limited to a piezoelectric ceramic micropump. Based on the inverse piezoelectric effect, the piezoelectric drive diaphragm vibrates, causing the cavity volume to change. The one-way valve controls the flow direction to generate a directional flow. Among them, the type of the one-way valve can be a passive valve, an active valve, or a specific structure valve. The passive valve can be opened and closed by deforming the valve body under the action of the fluid pressure. The active valve is controlled by a driver to open or close the one-way valve. The specific structure valve relies on the characteristics of certain fixed structure flow resistance and direction to achieve overall one-way flow. The volume of the micropump 330 can be in the range of 0.1 cubic centimeter (cm 3 ) to 1 cm 3 , the thickness can be in the range of 0.3 to 10 millimeters (mm), and the flow rate can be in the range of 0.1 to 500 milliliters per minute (mL / min).
[0095] Exemplarily, the diameter of the microchannel 380 can be set in the range of 10 to 10,000 micrometers. It should be understood that Figure 4The shape of the microchannel 380 shown is the cross-section in the direction perpendicular to the surface of the ceramic substrate 300. The shape of the cross-section of the microchannel 380 parallel to the surface of the ceramic substrate 300 can be various irregular shapes, such as S-shaped, parallel-connected type, series-parallel combined type, vortex type, cylindrical pin rib type, groove array type, etc. This example should not be construed as a limitation to the present application. The manufacturing materials of the microchannel layer 310 and the support layer 320 can be the same or different, including but not limited to high thermal conductivity ceramics such as alumina, aluminum nitride, and silicon nitride. The CTE of the microchannel layer 310 and the support layer 320 is the same or close, which can reduce the risk of cracking caused by thermal stress during heat dissipation when dissimilar materials are connected by welding or other connection methods.
[0096] The forming method of the ceramic substrate 300 with built-in heat dissipation microchannels provided by the present application can be that during the forming process of the ceramic substrate 300, a space for designing and reserving the microchannel 380 and placing the micropump 330 is designed, and sacrificial materials such as paraffin are laid according to the design. Through high-temperature volatilization, cracking, melting or dissolution, etc., an internal heat dissipation microchannel 380 and a space for placing the micropump 330 are generated during the forming process of the ceramic substrate 300.
[0097] Figure 5 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application. Figure 5 And Figure 4 Correspondingly, in some possible implementation scenarios, the micropump 330 may not be provided in some microchannel layers of the ceramic substrate 300. Exemplarily, a micropump can be provided in the microchannel layer close to the component 370, and no micropump is provided in the microchannel layer far from the component 370, so as to save resources.
[0098] It should be understood that the conductive channels in the ceramic substrate can be set according to requirements, and this figure should not be construed as a limitation to the present application.
[0099] Figure 6 It is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application.
[0100] The ceramic substrate 400 provided by the embodiment of the present application includes a microchannel layer 410, a support layer 420, a micropump 430, a micropump inlet 440, a micropump outlet 450, a metal line 460, a component 470, a microchannel 480, a microchannel layer inlet 411, and a microchannel layer outlet 413. Among them, the microchannel layer 410 is disposed on both sides of the support layer 420, and the microchannel layer 410 on one side of the support layer 420 is used to dispose the component 470.
[0101] Optionally, in some possible application scenarios, the upper and lower surfaces of the microchannel layer 410 need to be interconnected to meet the design requirements. The microchannel layer 410 includes a microchannel region and a non-microchannel region, and the non-microchannel region and the microchannel region are staggered in the surface direction parallel to the ceramic substrate 400. A conductive structure such as a conductive channel 490 can be provided in the non-microchannel region of the microchannel layer 410. It should be understood that the support layer 420 includes a structure in which a dielectric layer and a metal layer are stacked. The shaded part of the support layer 420 in the figure is the metal layer, and the blank part is the dielectric layer. The conductive channel 490 can connect the metal layers on the upper and lower surfaces.
[0102] It should be understood that if there is no interconnection requirement between the upper and lower surfaces of the microchannel layer 410, the conductive channel 490 may not be provided in the non-microchannel region of the microchannel layer 410.
[0103] There is at least one microchannel 480 with a diameter of millimeters or micrometers in the microchannel layer 410. Metal wires are provided inside the ceramic substrate 400 and led out on the surface of the ceramic substrate 400 to form metal lines 460. The micro-pump inlet 440 and the micro-pump outlet 450 are connected to the microchannel 480 of the microchannel layer 410. The micro-pump 430 drives the flow of the cooling medium in the microchannel 480, without the need for external power-providing equipment, and the formed ceramic substrate 300 itself is equipped with a cooling function.
[0104] The cooling medium enters the microchannel layer from the microchannel layer inlet 411, and flows out from the microchannel layer outlet 413 after passing through the microchannel 480 of the microchannel layer 410. The micro-pump 430 drives the cooling medium in the microchannel 480 to flow in and out of the micro-pump inlet 440 and the micro-pump outlet 450.
[0105] Compared with the structure shown in the ceramic substrate 200, the microchannel layer 410 of the ceramic substrate 400 is closer to components such as chips, which can reduce the thermal resistance between the components and the cooling medium and lower the working temperature of components such as chips. The microchannels and micro-pumps of this ceramic substrate are almost arranged in contact with the components, closer to the components 470, which can strengthen the heat exchange between the cooling medium and the components and has strong heat dissipation ability.
[0106] For the specific settings of the microchannels, the cooling medium and the micro-pump, reference can be made to Figure 3 the description, and the present application will not repeat it.
[0107] Figure 7 is a schematic structural diagram of another ceramic substrate provided by an embodiment of the present application. The microchannel layer 410 on one side of the support layer 420 is used to arrange components 470. For the specific settings of other structures in the ceramic substrate such as microchannels, the cooling medium and the micro-pump, reference can be made to Figure 3 and Figure 6 the description, and the present application will not repeat it.
[0108] The ceramic substrate provided by this application can select and design the microchannel form according to requirements such as interconnection, vias, device avoidance, heat dissipation, etc. The shape of the microchannel includes, but is not limited to, Figures 8 - 13 the different microchannel forms shown.
[0109] Figure 8 Figure 6 is a schematic diagram of an S-shaped microchannel provided by an embodiment of this application. In this form, the cooling medium stays in the microchannel area for a long time, has enough time for sufficient heat exchange, and takes away heat. Among them, conductive channels can be opened in all non-channel areas to achieve electrical interconnection.
[0110] Figure 9 Figure 10 is a schematic diagram of a parallel-type microchannel provided by an embodiment of this application. In this form, the flow resistance of the cooling medium in the blank microchannel area is small and the flow rate is large. Among them, conductive channels can be opened in all shaded non-channel areas to achieve electrical interconnection.
[0111] Figure 10 Figure 14 is a schematic diagram of a series-parallel combined microchannel provided by an embodiment of this application. In this form, the flow resistance of the cooling medium in the blank microchannel area is small and the flow rate is large. Among them, conductive channels can be opened in all shaded non-channel areas to achieve electrical interconnection.
[0112] Figure 11 Figure 18 is a schematic diagram of a vortex-type microchannel provided by an embodiment of this application. This form can be used when avoiding some devices embedded in the ceramic substrate. In this form, the cooling medium stays in the blank microchannel area for a long time, has enough time for sufficient heat exchange, and takes away heat. Among them, conductive channels can be opened in all shaded non-channel areas to achieve electrical interconnection.
[0113] Figure 12 Figure 22 is a schematic diagram of a cylindrical pin fin type microchannel provided by an embodiment of this application. Dense cylindrical pin fins can be used near high-power devices to enhance heat transfer. Among them, conductive channels can be opened in all shaded non-channel areas to achieve electrical interconnection.
[0114] Figure 13 Figure 26 is a schematic diagram of a groove array type microchannel provided by an embodiment of this application. In this form, the flow resistance of the cooling medium in the blank microchannel area is small and the flow rate is large. Among them, conductive channels can be opened in all shaded non-channel areas to achieve electrical interconnection.
[0115] The microchannel layer in the ceramic substrate and the support layer are integrally processed and formed. The microchannel layer can be placed on the back or the same side of the ceramic substrate where components are installed, or can be located inside the ceramic substrate and is a part of the ceramic substrate itself. The preparation process of the microchannel layer can adopt the same tape casting method as the ceramic substrate, or can also adopt the sintering-welding method of cold pressing and sintering and then welding with the ceramic substrate.
[0116] Figure 14 It is an exemplary flowchart of a method for preparing a ceramic substrate provided by an embodiment of the present application.
[0117] 610, form a microchannel layer.
[0118] The microchannel layer includes at least one microchannel for accommodating a cooling medium.
[0119] The diameter of the microchannel can be set in the range of 10 to 10,000 microns. The shapes include S-shaped, parallel-connected type, series-parallel combined type, vortex type, cylindrical pin fin type, groove array type, etc. The cooling medium can be various flowable liquids or gases. The present application does not make any limitation on the temperature range of the cooling medium. If the function of the microchannel layer is cooling, a cooling medium with a temperature lower than the working temperature can be used. The thermal resistance of the microchannel layer can be less than 0.1 Kelvin per watt (K / W). For example, for a chip device with a TDP of 18W, using -10°C cooling water can achieve a chip working temperature below 0°C. If the function of the microchannel layer is to control the temperature of the ceramic substrate and each device, a fluid medium with a temperature higher than the working temperature of the components can also be used to make each part of each device reach the required thermal design temperature.
[0120] Exemplarily, during the forming process of the ceramic substrate, the space for designing and reserving microchannels and placing micropumps can be designed, and sacrificial materials such as paraffin are laid according to the design. Through high-temperature volatilization, cracking, melting or dissolution, etc., a microchannel layer is formed during the forming process of the ceramic substrate.
[0121] 620, set a micropump in the microchannel layer.
[0122] The micropump is communicated with the microchannels of the microchannel layer and is used to drive the flow of the cooling medium without an external power supply device.
[0123] The forms of the micropump include but are not limited to piezoelectric ceramic micropumps. Based on the inverse piezoelectric effect, the piezoelectric drive diaphragm vibrates, causing the cavity volume to change, and the one-way valve controls the flow direction to generate a directional flow. Among them, the type of the one-way valve can be a passive valve, an active valve or a specific structure valve. The passive valve can be opened and closed by deforming the valve body under the action of fluid pressure. The active valve is controlled by a driver to open or close the one-way valve. The specific structure valve relies on the characteristics of certain fixed structure flow resistance and direction to achieve overall one-way flow. The volume of the micropump can be in the range of 0.1 cm 3 ~1 cm 3 The range is from 0.3 to 10 mm in thickness and from 0.1 to 500 mL / min in flow rate.
[0124] Figure 15 It is an exemplary flowchart of a method for preparing a ceramic substrate by the tape casting method provided by an embodiment of the present application.
[0125] 701, Preparation of ceramic raw materials.
[0126] Prepare the required ceramic raw materials, which usually exist in the form of powder. The selection of raw materials is determined according to the characteristics of the ceramic substrate and application requirements.
[0127] 702, Raw material modulation.
[0128] Mix the ceramic powder with an appropriate amount of solvent to form a fluid slurry. The choice of solvent depends on the characteristics of the ceramic powder, and commonly used solvents include water, organic solvents, etc.
[0129] 703, Preparation of doctor blade die.
[0130] Select a suitable doctor blade die, whose shape and size should match the required ceramic substrate. The doctor blade die is usually made of metal or ceramic materials and has a flat surface.
[0131] 704, Doctor blade operation.
[0132] Pour the modulated ceramic slurry evenly into the doctor blade die, and then by controlling the speed and pressure of the doctor blade machine, make the slurry form a uniform thin layer on the die surface.
[0133] 705, Microchannel laying.
[0134] In the doctor blade die, lay easy-to-process materials, such as paraffin, according to the different shapes of the designed microchannel layer. These materials can be removed or processed in subsequent treatments through high-temperature volatilization, cracking, melting, or easy dissolution, etc., to form the required microchannel structure.
[0135] 706, Curing.
[0136] After doctor blading, the ceramic substrate needs to be cured to gradually volatilize the solvent in the slurry and combine with the ceramic particles to form a solid substrate. Curing can be completed by natural drying, oven drying, or vacuum oven drying.
[0137] 707, Sintering.
[0138] The cured ceramic substrate needs to be sintered to further improve its density and mechanical properties. The sintering temperature and time depend on the specific ceramic material.
[0139] 708, Finishing.
[0140] The sintered ceramic substrate can be further processed, such as cutting, grinding, polishing, etc., to meet specific shape and size requirements.
[0141] 709, Surface treatment.
[0142] As needed, the ceramic substrate can be surface-treated, such as polished and cleaned, to improve its surface flatness and smoothness.
[0143] 710, Inspection and testing.
[0144] Finally, the prepared ceramic substrate is inspected and tested, including dimension measurement, surface quality assessment, and performance testing, etc., to ensure that it meets the design requirements and quality standards.
[0145] Figure 16 It is an exemplary flowchart of preparing a ceramic substrate by a sintering-welding method provided by an embodiment of the present application.
[0146] 801, Preparation of ceramic raw materials.
[0147] The required ceramic raw materials are prepared in the form of powder. Usually, a certain amount of polyvinyl alcohol (PVA) is added to the ceramic powder as a binder to improve the plasticity and formability of the powder.
[0148] 802, Paraffin filling.
[0149] The paraffin is arranged according to the designed heat dissipation microchannels, and the paraffin will volatilize completely during the subsequent sintering process.
[0150] 803, Filling and tamping.
[0151] The function of filling is to make the ceramic powder fully cover the paraffin filling, and the purpose of tamping is to improve the density of the green body.
[0152] 804, Cold pressing.
[0153] The filled and tamped mixture is cold-pressed. Common cold-pressing methods include cold isostatic pressing and dry pressing.
[0154] 805, Green body processing.
[0155] The green body after cold pressing needs to be further processed, such as cutting, grinding, and polishing, to obtain a ceramic substrate with the required shape and size.
[0156] 806, Drying.
[0157] The green body is placed under appropriate environmental conditions, and the moisture in it is removed by natural drying or oven drying. The purpose of drying is to improve the strength and stability of the ceramic substrate.
[0158] 807, Debinding.
[0159] Before sintering, the polyvinyl alcohol glue in the ceramic substrate needs to be discharged. Common methods are heating or using a solvent to dissolve it.
[0160] 808, Sintering.
[0161] Place the debinded ceramic substrate in a high-temperature furnace for sintering. During sintering, paraffin or residues will volatilize, and the ceramic particles will bond together to form a dense ceramic substrate. The sintering temperature and time will depend on the specific ceramic material.
[0162] 809, Finishing.
[0163] The sintered ceramic substrate needs to be finished, such as grinding, polishing, and drilling, to meet specific requirements and dimensions.
[0164] 810, Surface metallization.
[0165] To provide better electrical conductivity and connectivity, the surface of the ceramic substrate will be metallized. Common metallization methods include spraying metal powder, electroplating, or electroless plating of metal layers, etc.
[0166] 811, Welding and forming with the substrate.
[0167] Finally, the ceramic substrate with surface metallization can be welded to other electronic components or substrates to complete the final forming process.
[0168] In the embodiments of the present application, the microchannel layer and the support layer are integrally formed during the preparation process, without the need to use Tim material, meeting the requirements of vacuum and clean environment, and having higher reliability. The CTE of the support layer and the microchannel layer is the same or close, which can reduce the cracking risk caused by thermal stress during heat dissipation due to the connection method such as welding of dissimilar materials. The ceramic substrate containing microchannels has the advantages of high thermal conductivity, high heat resistance, high insulation, high strength, and corrosion resistance. At the same time, vias and traces can be opened in the non-microchannel area of the microchannel layer of the ceramic substrate, and the internal microchannel layer does not affect the wiring (interconnection) function of the ceramic substrate. The ceramic substrate provided by the embodiments of the present application can select and design the microchannel form according to the requirements of interconnection, vias, device avoidance, heat dissipation, etc., avoid devices, reduce vibration, enhance heat transfer, and reduce the operating temperature of components.
[0169] Unless otherwise specified, all technical and scientific terms used in the embodiments of the present application have the same meaning as commonly understood by those skilled in the technical field of the present application. The terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the scope of the present application. It should be understood that the above is for illustrative purposes only, and the above examples are only to help those skilled in the art understand the embodiments of the present application, rather than to limit the embodiments of the application to the specific values or specific scenarios shown. Those skilled in the art can obviously make various equivalent modifications or changes based on the examples given above, and such modifications and changes also fall within the scope of the embodiments of the present application.
[0170] As described above, it is only the specific implementation manner of the present application. However, the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims described above.
Claims
1. A ceramic substrate, characterized in that: The ceramic substrate is provided with a microchannel layer and a micropump. The microchannel layer includes at least one microchannel, and the microchannel is used to contain a cooling medium; The micro pump is communicated with the micro channel of the micro channel layer, and the micro pump is used to drive the flow of the cooling medium.
2. The ceramic substrate according to claim 1, characterized in that: The non-microchannel region of the microchannel layer and the microchannels are staggered in a first direction, the first direction is parallel to the surface of the ceramic substrate, and the non-microchannel region is used to set a conductive structure.
3. The ceramic substrate according to claim 1 or 2, characterized in that: It also includes a supporting layer, which is stacked with the microfluidic layer and is used to support the microfluidic layer.
4. The ceramic substrate according to claim 3, characterized in that: The side of the microchannel layer away from the supporting layer is used for arranging components.
5. The ceramic substrate according to claim 3, characterized in that: The support layer is arranged on both sides of the microfluidic layer, wherein the support layer on one side of the microfluidic layer is used for arranging components.
6. The ceramic substrate according to claim 3, characterized in that: The side of the support layer away from the microfluidic layer is used for arranging components.
7. The ceramic substrate according to any one of claims 3 to 6, characterized in that: An absolute value of a difference between a thermal expansion coefficient of the microchannel layer and a thermal expansion coefficient of the support layer is smaller than a preset threshold.
8. The ceramic substrate according to any one of claims 1 to 7, characterized in that: The shape of the cross section of the microchannel parallel to the surface of the ceramic substrate includes any one or more of an S-type, a parallel type, a series-parallel combination type, a vortex type, a cylindrical pin-fin type, and a groove array type.
9. The ceramic substrate according to any one of claims 1 to 8, characterized in that: The width or diameter of the microchannel is in the range of 10 micrometers to 10,000 micrometers.
10. The ceramic substrate according to any one of claims 1 to 9, characterized in that: The micro-channel layer comprises an inlet and an outlet. The cooling medium enters the micro-channel layer from the inlet and flows out of the micro-channel layer from the outlet.
11. A method for preparing a ceramic substrate, characterized in that: include: forming a microchannel layer, wherein the microchannel layer comprises at least one microchannel, and the microchannel is used to accommodate a cooling medium; A micro pump is arranged on the micro channel layer, the micro pump is communicated with the micro channel of the micro channel layer, and the micro pump is used to drive the flow of the cooling medium.
12. The method according to claim 11, characterized in that The non-microchannel region of the microchannel layer and the microchannels are staggered in a first direction, the first direction is parallel to the surface of the ceramic substrate, and the non-microchannel region is used to set a conductive structure.
13. The method according to claim 11 or 12, characterized in that: The method further comprises: A support layer is formed and stacked with the microfluidic layer to support the microfluidic layer.
14. The method according to claim 13, characterized in that The method further comprises: Components are arranged on a side of the microfluidic layer away from the supporting layer.
15. The method according to claim 13, characterized in that The method further comprises: Components are arranged on the support layer at one side of the microfluidic channel layer, wherein the support layer is arranged on both sides of the microfluidic channel layer.
16. The method according to claim 13, characterized in that The method further comprises: Components are arranged on a side of the support layer away from the microfluidic channel layer.
17. The method according to any one of claims 13 to 16, characterized in that An absolute value of a difference between a thermal expansion coefficient of the microchannel layer and a thermal expansion coefficient of the support layer is smaller than a preset threshold.
18. The method according to any one of claims 11 to 17, characterized in that The shape of the cross section of the microchannel parallel to the surface of the ceramic substrate includes any one or more of an S-type, a parallel type, a series-parallel combination type, a vortex type, a cylindrical pin-fin type, and a groove array type.
19. The method according to any one of claims 11 to 18, characterized in that The width or diameter of the microchannel is in the range of 10 micrometers to 10,000 micrometers.
20. The method according to any one of claims 11 to 19, characterized in that The micro-channel layer comprises an inlet and an outlet. The cooling medium enters the micro-channel layer from the inlet and flows out of the micro-channel layer from the outlet.
21. An electronic device, characterized in that: The invention comprises a component and a ceramic substrate as claimed in any one of claims 1 to 10, wherein the component is arranged on the ceramic substrate.