Heat sink plate and preparation method therefor, and power device

Abstract

The present invention relates to the technical field of heat sink materials, and specifically relates to a heat sink plate and a preparation method therefor, and a power device. The bottom of the heat sink plate is provided with an upward protruding arc groove, and a composite layer is disposed within the upward protruding arc groove, the composite layer conforming to the curvature of the upward protruding arc groove; the composite layer is formed from multiple layers of metal-nonmetal composite powders, wherein the content of metal powder in the multiple layers of metal-nonmetal composite powders gradually decreases in the protruding direction of the upward protruding arc groove. The heat sink plate has a certain degree of curvature; thus, during operation, a metal-rich end thereof elongates when heated, such that the curvature of the heat sink plate decreases, leading to an increase in the contact area between the heat sink plate and a device, and thereby improving thermal conductivity and reducing chip temperature.

Description

Heat sink plate, its preparation method and power device Technical fields:

[0001] This invention relates to the field of heat sink materials technology, and more specifically, to heat sink plates, their preparation methods, and power devices. Background technology:

[0002] Server chips, IGBT chips, and other power devices are rapidly becoming smaller and more multifunctional. The evolution of chip size from 90nm to 28nm and then to 2nm has led to an exponential increase in the heat generated per unit area of ​​power devices, resulting in severe heat dissipation problems. Since power devices generate a large amount of heat during operation, if this heat cannot be dissipated effectively and promptly, the accumulated heat will lead to performance degradation or even damage. Data shows that within a certain range, for every 10°C increase in temperature, the performance of power devices decreases by more than 50%. Therefore, heat dissipation plays a crucial role in power device performance. The heat transfer path for power devices is as follows: chip / diode → chip under-soldering layer → DBC copper layer → DBC ceramic layer → DBC copper layer → substrate soldering layer → heat dissipation substrate → thermally conductive silicone → heat sink → external environment. As the core component of the heat dissipation structure, the thermal conductivity of the heat sink has a decisive impact on the performance of the power module.

[0003] Currently, most materials used to manufacture heat sinks are high thermal conductivity metal-based composite thermally conductive materials, such as silicon carbide / aluminum (SiCp / Al) with a thermal conductivity of 170–200 W / m*K; copper-tungsten alloy (Cu / W) with a thermal conductivity of 180–200 W / m*K; copper-tungsten-copper-copper (CPC) with a thermal conductivity of 200–300 W / m*K; and diamond copper with a thermal conductivity of 600–900 W / m*K. Diamond copper currently has the best thermal conductivity among all materials suitable for industrial applications. However, due to the large difference in thermal expansion coefficients between diamond and copper, the heat sink warps as the temperature rises during application, creating gaps between the heat sink and the chip. This results in a significant decrease in thermal conductivity and a reduction in the performance of power devices.

[0004] In view of this, the present invention is proposed. Summary of the Invention:

[0005] The purpose of this invention is to provide a heat sink plate, its preparation method, and a power device. An embodiment of this invention provides a novel heat sink plate with a certain curvature. During application, upon heating, the metal-rich end elongates, the curvature of the heat sink plate decreases, the contact area between the heat sink plate and the device increases, the thermal conductivity increases, and the chip temperature decreases.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides a heat sink plate, wherein the bottom of the heat sink plate is provided with an upward convex arc groove, and a composite layer is provided in the upward convex arc groove, wherein the composite layer is fitted with the arc of the upward convex arc groove.

[0008] The composite layer is a composite layer formed by multiple metal-nonmetal composite powders;

[0009] The content of metal powder in the multilayer metal-nonmetal composite powder decreases along the direction of the convex arc groove.

[0010] In an optional embodiment, the content of metal powder in the multilayer metal-nonmetal composite powder decreases at a gradient along the direction of the convex arc groove.

[0011] In an optional embodiment, the metal-nonmetal composite powder in the bottom layer of the composite layer comprises 70-90% metal powder and 10-30% nonmetal powder by weight percentage.

[0012] The metal-nonmetal composite powder in the top layer of the composite layer comprises 10-30% metal powder and 70-90% nonmetal powder.

[0013] In an optional embodiment, the non-metallic powder includes diamond powder and ceramic material powder, preferably any one or at least a combination of two of diamond powder, boron nitride powder, aluminum nitride powder, silicon carbide powder and silicon nitride powder.

[0014] The best option is diamond powder;

[0015] Preferably, the particle size of the non-metallic powder is 100-500 μm.

[0016] In an optional embodiment, the metal powder includes elemental copper powder, copper alloy powder, elemental aluminum powder, and aluminum alloy powder.

[0017] The preferred materials are elemental copper powder, tungsten copper powder, molybdenum copper powder, and elemental aluminum powder; the most preferred material is elemental copper powder.

[0018] Preferably, the particle size of the metal powder is 0.1-10 μm.

[0019] In an optional embodiment, the composite layer has at least 3 layers; preferably 3-8 layers.

[0020] Preferably, the thickness of each layer in the composite layer is <1mm.

[0021] In an optional implementation, the arc shape of the upper convex groove meets the following requirements:

[0022] R / L = 5 to 25, where R represents the radius of curvature and L represents the length of the heat sink plate.

[0023] Secondly, the present invention provides a method for preparing the heat sink plate described in the foregoing embodiments, wherein multiple layers of metal-nonmetal composite powder are laid in the arc groove of a metal plate having an arc groove, and then hot-pressed and sintered.

[0024] In this process, the content of metal powder in the multilayer metal-nonmetal composite powder decreases upwards along the bottom of the arc-shaped groove; the arc shape of the arc-shaped groove is an upward convex arc.

[0025] In an optional embodiment, the conditions for hot pressing sintering include: a temperature of 600–1150°C, a holding time of 10–60 min, a pressure of 1–10 MPa, a radius of curvature of R, and a holding time of 5–60 min.

[0026] Thirdly, the present invention provides a power device comprising the heat sink plate and the chip described in the foregoing embodiments, wherein the chip and the heat sink plate are connected.

[0027] The present invention offers the following advantages: This invention provides a novel heat sink plate with an upwardly convex arc and a composite layer of metal powder and non-metal powder gradients. This allows the metal-rich end of the heat sink plate to elongate after prolonged use and heating, reducing the arc of the heat sink plate, increasing the contact area between the heat sink plate and the device, increasing thermal conductivity, and lowering the chip temperature. This avoids the large difference in thermal expansion coefficients between metal and non-metal, which can cause the heat sink plate to warp as the temperature rises during application, leading to gaps between the heat sink plate and the chip, thus ensuring the performance of the power device. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 is a front view of the copper substrate provided in Embodiment 1 of the present invention;

[0030] Figure 2 is a top view of the copper substrate provided in Embodiment 1 of the present invention;

[0031] Figure 3 is a scanning electron microscope image of the copper powder provided in Example 1 of the present invention;

[0032] Figure 4 is a scanning electron microscope image of the diamond powder provided in Example 1 of the present invention;

[0033] Figure 5 is a schematic diagram of the structure of the heat sink plate provided in Embodiment 1 of the present invention;

[0034] Figure 6 is a schematic diagram of hot pressing sintering provided in an embodiment of the present invention. Detailed implementation method:

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0036] In a first aspect, the present invention provides a heat sink plate, which is a plate with an arc shape; the arc shape is an upward convex arc, which means that the direction of the arc bends upward and the arc opening downward.

[0037] Specifically, the bottom of the heat sink plate is provided with an upward convex arc groove. The upward convex arc groove refers to a groove on the bottom of the heat sink plate, which has a certain curvature, with the arc opening facing downward and the curvature direction upward.

[0038] The arc shape of the convex groove meets the following requirements: R / L = 5~25, where R represents the radius of curvature and L represents the length of the heat sink plate. When the arc shape meets this requirement, the heat sink plate can flatten after being heated during use, preventing the heat sink plate from warping, increasing the contact area between the heat sink plate and the chip, and improving the heat dissipation effect.

[0039] Furthermore, a composite layer is provided within the convex arc groove, and the composite layer is completely fitted with the curvature of the convex arc groove. That is to say, the composite layer also has an arc-shaped layer structure, and the curvature and bending direction of the composite layer are consistent with the curvature and bending direction of the convex arc groove.

[0040] Furthermore, the composite layer is a composite layer formed by multiple layers of metal-nonmetal composite powder. Specifically, the composite layer is a multi-layer structure, with each layer being a layer structure formed by metal-nonmetal composite powder. The content of metal powder and nonmetal powder in each layer is different. Specifically, the content of metal powder in the multiple layers of metal-nonmetal composite powder decreases along the direction of the convex arc groove, that is, the content of metal powder in the multiple layers of metal-nonmetal composite powder gradually decreases from bottom to top.

[0041] In this embodiment of the invention, the heat sink plate is set as an arc-shaped plate, combined with a composite layer, and the metal powder content in the composite layer gradually decreases from bottom to top. As a result, after the power device is used, the metal-rich end of the heat sink plate elongates, the arc of the heat sink plate decreases, the contact area between the heat sink plate and the device increases, the thermal conductivity increases, the chip temperature decreases, and the performance of the power device is improved.

[0042] Furthermore, the content of metal powder in the multilayer metal-nonmetal composite powder decreases from bottom to top. This can be a uniform gradient decrease, for example, the difference between the metal powder content of the first layer and the second layer is A, and the difference between the metal powder content of the second layer and the third layer is B, where A and B are the same. Alternatively, it can be a non-gradient decrease, for example, the difference between the metal powder content of the first layer and the second layer is A, and the difference between the metal powder content of the second layer and the third layer is B, where A and B are different; in this case, A can be greater than B, or A can be less than B. The first layer is relatively close to the bottom of the heat sink plate, and the second and third layers are arranged sequentially from bottom to top.

[0043] In a preferred embodiment of the present invention, the content of metal powder in the multilayer metal-nonmetal composite powder decreases at a gradient along the direction of the convex arc groove, which is more conducive to forming a stable composite layer structure. This, in turn, helps the curvature of the heat sink plate to decrease uniformly after being heated, improves the adhesion between the heat sink plate and the device, and enhances the performance of the power device.

[0044] The composite layer has a minimum of 3 layers; preferably 3-8 layers; for example, any number between 3 and 8 layers. Furthermore, the thickness of each layer of metal-nonmetal composite powder in the composite layer is <1 mm.

[0045] Limiting the number and thickness of each layer in the composite layer can further improve its performance. This helps reduce the curvature of the heat sink after heating, thus improving the performance of power devices. Too many layers result in an excessively thick heat sink, failing to meet usage requirements. Too few layers reduce the thermal conductivity of the heat sink, hindering heat dissipation. Furthermore, prolonged use can easily lead to separation between the heat sink and the chip, significantly reducing the performance of the power devices.

[0046] Furthermore, by mass percentage, the bottom layer of the composite layer comprises 70-90% metal powder and 10-30% non-metal powder; this bottom layer refers to the layer that directly interacts with the upper convex arc groove; the total mass of metal powder and non-metal powder in the metal-non-metal composite powder is 100%. In this case, the metal-non-metal composite powder forming this layer is 70% metal powder and 30% non-metal powder; 75% metal powder and 25% non-metal powder; or 80% metal powder and 20% non-metal powder; or 85% metal powder and 15% non-metal powder; or 90% metal powder and 10% non-metal powder.

[0047] The top layer of the composite layer comprises 10-30% metal powder and 70-90% non-metal powder. This top layer refers to the layer furthest from the upper convex groove. In this case, the metal-non-metal composite powder forming this layer may be 10% metal powder and 90% non-metal powder; or 15% metal powder and 85% non-metal powder; or 20% metal powder and 80% non-metal powder; or 25% metal powder and 75% non-metal powder; or 30% metal powder and 70% non-metal powder.

[0048] The composition of the metal-nonmetal composite powder forming the layered structure between the top and bottom layers is determined based on the number of composite layers and the composition of the top and bottom metal-nonmetal composite powders. For example, (metal powder content in the top metal-nonmetal composite powder minus metal powder content in the bottom metal-nonmetal composite powder) / (number of composite layers - 1) = the reduction in metal powder content for each layer. Then, the metal powder content in the bottom metal-nonmetal composite powder is reduced layer by layer according to the corresponding metal powder content, thereby obtaining the metal powder content and nonmetal powder content in each layer of the metal-nonmetal composite powder.

[0049] For example, the top layer of the metal-nonmetal composite powder consists of 30% metal powder and 70% nonmetal powder; the bottom layer consists of 90% metal powder and 10% nonmetal powder; and the composite layer has four layers. When the metal powder content decreases in a gradient, each layer is reduced by 20%. Specifically, the bottom layer consists of 90% metal powder and 10% nonmetal powder; the middle layer, relatively close to the bottom layer, consists of 70% metal powder and 30% nonmetal powder; the middle layer, relatively close to the top layer, consists of 50% metal powder and 50% nonmetal powder; and the top layer consists of 30% metal powder and 70% nonmetal powder.

[0050] Furthermore, the non-metallic powder includes diamond powder and ceramic material powder, preferably any one or at least two combinations of diamond powder, boron nitride powder, aluminum nitride powder, silicon carbide powder and silicon nitride powder; most preferably diamond powder.

[0051] The particle size of the non-metallic powder is 100-500 μm. For example, it can be 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm or any value between 100-500 μm.

[0052] Furthermore, the metal powder includes elemental copper powder, copper alloy powder, elemental aluminum powder, and aluminum alloy powder; for example, including but not limited to elemental copper powder, tungsten copper powder, molybdenum copper powder, and elemental aluminum powder; most preferably, elemental copper powder.

[0053] The particle size of the metal powder is 0.1-10 μm. For example, it can be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any value between 0.1-10 μm.

[0054] Secondly, the present invention provides a method for preparing the heat sink plate described in the foregoing embodiments, wherein multiple layers of metal-nonmetal composite powder are laid in the arc-shaped groove of a metal plate, and then hot-pressed and sintered. The specific process is as follows:

[0055] A groove with a certain curvature is machined on a metal substrate. The groove has an upward convex arc shape; specifically, the curvature of the groove curves upward and the opening faces downward. Simultaneously, a metal carrier plate matching the dimensions of the groove is machined.

[0056] The curvature of the metal substrate must meet the requirement R / L = 5~25; where R represents the radius of curvature and L represents the length of the metal substrate. The thickness of the metal substrate must be <0.1mm.

[0057] Metal powder and non-metal powder in different proportions are mixed evenly to obtain mixed powders in different proportions. The mixed powders in different proportions can be labeled as MP1, MP2, MP3 or MP4, etc.

[0058] Different proportions of mixed powder are evenly spread on a metal carrier plate to form a multilayer structure, and the metal carrier plate is placed in a groove in a metal substrate. In the multilayer structure, the bottom layer of mixed powder is placed to completely fit the arc shape, and then each layer in the multilayer structure is placed to completely fit the arc shape of the adjacent layer to obtain a green embryo.

[0059] The thickness of the spread mixed powder is less than 1 mm. Meanwhile, the proportion of metal powder in the mixed powder gradually decreases from bottom to top.

[0060] The green blank is placed in a mold and then hot-pressed and sintered in a vacuum hot press furnace (see Figure 6 for a schematic diagram of hot pressing and sintering) to obtain a cooked blank. The mold in the vacuum hot press furnace is also arc-shaped, and the arc shape matches the arc shape of the groove provided on the metal substrate.

[0061] Furthermore, the conditions for hot pressing sintering include: a temperature of 600–1150℃, a holding time of 10–60 min, a pressure of 1–10 MPa, a radius of curvature of R, and a holding time of 5–60 min.

[0062] Specifically, before hot pressing, the equipment is evacuated to a vacuum level of 5*10. -2 Below Pa; heat to 600-1150℃ at a rate of 5-25℃ / min, hold for 10-60min, pressure 1-10MPa, pressure head radius of R, holding time 5-60min.

[0063] The radius of curvature R of the heat sink plate and the radius of curvature R of the pressure head are the same value, and the length L of the heat sink plate and the length L of the metal substrate are the same value.

[0064] Thirdly, the present invention provides a power device comprising the heat sink plate and the chip described in the foregoing embodiments, wherein the chip and the heat sink plate are connected.

[0065] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0066] Examples 1-16 and Comparative Examples 1-6

[0067] This invention provides a method for preparing a heat sink plate, comprising:

[0068] A groove with a certain curvature is machined on a copper substrate. The groove has an upward convex arc shape; specifically, the curvature of the groove curves upward and the opening faces downward. See Figures 1 and 2 for the front and top views of the copper substrate. Simultaneously, a copper carrier plate matching the dimensions of the groove is machined.

[0069] Copper powder (see Figure 3 for its scanning electron microscope image) and diamond powder (see Figure 4 for its scanning electron microscope image) in different proportions were mixed evenly to obtain mixed powders in different proportions.

[0070] Mixed powders of different proportions are evenly spread on a copper substrate to form a multilayer structure, and the copper substrate is placed in a groove in the copper substrate. The bottom layer of the multilayer structure is placed to completely fit the arc shape, and then each subsequent layer in the multilayer structure is placed to completely fit the arc shape of the adjacent layer to obtain a green embryo.

[0071] The green embryo is placed in a vacuum hot press furnace for hot pressing and sintering to obtain a cooked embryo.

[0072] See Figure 5 for a schematic diagram of the obtained heat sink plate.

[0073] Specifically, the values ​​of R / L, the number of composite layers, the thickness of each layer, the composition of the top metal-nonmetal composite powder (the content of metal powder and nonmetal powder are both mass content), the composition of the bottom metal-nonmetal composite powder, the sintering temperature, the holding time, the particle size of diamond, the particle size of copper, etc. in Examples 1-16 and Comparative Examples 1-6 are shown in the following table.

[0074] Test case

[0075] The thermal conductivity of the heat sink plates in Examples 1-16 and Comparative Examples 1-6 was tested. The thermal conductivity was measured using the transient method with a Netzsch LFA467 laser thermal conductivity meter. The test results are shown in the table below:

[0076] As shown in Table 2, the heat sink plate provided in this embodiment of the invention has high thermal conductivity. Changing the parameters of the heat sink plate, such as the R / L value, the number of composite layers, or the particle size of the raw materials, will significantly reduce the thermal conductivity of the resulting heat sink plate. Furthermore, the power devices prepared using the heat sink plate provided in this embodiment of the invention show virtually no change in performance after continuous long-term use. Analysis of the power devices reveals that the heat sink plate and the chip remain tightly connected, without any warping or other phenomena. However, the power devices prepared using Comparative Examples 1-6 show a significant decrease in performance after the same period of long-term use. Further analysis reveals that gaps exist between the heat sink plate and the chip in the power devices formed in Comparative Examples 1-6, leading to a significant reduction in thermal conductivity.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat sink plate, characterized in that, The bottom of the heat sink plate is provided with an upward convex arc groove, and a composite layer is provided inside the upward convex arc groove. The composite layer fits the arc of the upward convex arc groove. The composite layer is a composite layer formed by multiple layers of metal-nonmetal composite powders. The content of metal powder in the multilayer metal-nonmetal composite powder decreases along the direction of the convex arc groove.

2. The heat sink plate according to claim 1, characterized in that, The content of metal powder in the multilayer metal-nonmetal composite powder decreases at a gradient along the direction of the convex arc groove.

3. The heat sink plate according to claim 1, characterized in that, By mass percentage, the metal-nonmetal composite powder in the bottom layer of the composite layer comprises 70-90% metal powder and 10-30% nonmetal powder; The metal-nonmetal composite powder in the top layer of the composite layer comprises 10-30% metal powder and 70-90% nonmetal powder.

4. The heat sink plate according to claim 3, characterized in that, The non-metallic powder includes diamond powder and ceramic material powder, preferably any one or at least a combination of two of diamond powder, boron nitride powder, aluminum nitride powder, silicon carbide powder and silicon nitride powder; The best option is diamond powder; Preferably, the particle size of the non-metallic powder is 100-500 μm.

5. The heat sink plate according to claim 3, characterized in that, The metal powder includes elemental copper powder, copper alloy powder, elemental aluminum powder, and aluminum alloy powder. The preferred materials are elemental copper powder, tungsten copper powder, molybdenum copper powder, and elemental aluminum powder; the most preferred material is elemental copper powder. Preferably, the particle size of the metal powder is 0.1-10 μm.

6. The heat sink plate according to any one of claims 1-5, characterized in that, The composite layer has a minimum of 3 layers; preferably 3-8 layers. Preferably, the thickness of each layer in the composite layer is <1mm.

7. The heat sink plate according to any one of claims 1-5, characterized in that, The arc shape of the upper convex groove meets the following requirements: R / L = 5 to 25, where R represents the radius of curvature and L represents the length of the heat sink plate.

8. A method for preparing the heat sink plate according to claim 1, characterized in that, Multiple layers of metal-nonmetal composite powder are laid in the arc-shaped groove of a metal plate, and then hot-pressed and sintered. In this process, the content of metal powder in the multilayer metal-nonmetal composite powder decreases upwards along the bottom of the arc-shaped groove; the arc shape of the arc-shaped groove is an upward convex arc.

9. The preparation method according to claim 8, characterized in that, The conditions for hot pressing sintering include: temperature of 600-1150℃, holding time of 10-60 min, pressure of 1-10 MPa, radius of curvature of the pressure head of R, and holding time of 5-60 min.

10. A power device, characterized in that, It includes the heat sink plate and the chip as described in claim 1, wherein the chip and the heat sink plate are connected.

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