Chip packaging heat dissipation liquid cooling device with sandwich structure

Abstract

The invention discloses a chip packaging heat dissipation liquid cooling device with a sandwich structure. The chip packaging heat dissipation liquid cooling device comprises a heat dissipation base and a chip welding table located on the heat dissipation base. The chip welding table is a sandwich structure composite plate with copper layers on the upper and lower surfaces, and the heat dissipation base adopts a diamond metal composite plate with a sandwich structure; and the chip welding table is connected with the heat dissipation base in a welding manner. The sandwich structure with high thermal conductivity and an adjustable thermal expansion coefficient is used for replacing a traditional heat dissipation copper bottom plate with low thermal conductivity, the heat transfer capacity and the system heat dissipation capacity of the liquid cooling device can be effectively improved while the size of the cold plate is not increased, and meanwhile the scheme is a low-cost scheme.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a chip package heat dissipation liquid cooling device with a sandwich structure. Background Art

[0002] With the accelerating penetration of computing power into all industries and fields, and the deep integration of the Internet, big data, artificial intelligence, etc. with the real economy, the computing power demand in the industry has grown rapidly, leading to an increase in chip power and a power consumption breakthrough of kilowatts. The popularity of generative intelligent AIGC and the application breakthrough of AI large models have led to a rapid increase in the shipments of GPUs. Currently, AI large models use GPUs extensively for both training and inference. In addition to NVIDIA and AMD, major manufacturers are also developing their own GPU chips. The overall global shipments of GPUs will continue to climb and reach about 200 million by 2030. As the best heat dissipation solution for GPUs, liquid cooling will also rise accordingly.

[0003] In newly added GPU computing power centers, due to the rapid increase in power density, refrigeration has become a serious challenge, and liquid cooling has become an inevitable choice. Considering factors such as initial investment cost, maintainability, PUE effect, and industrial maturity, cold plates and single-phase immersion cooling are more advantageous compared to other liquid cooling technologies and are the mainstream solutions in the industry currently.

[0004] The most common composition of a liquid cooling plate (usually a closed cavity made of heat-conducting metals such as copper and aluminum) is: a cold plate bottom plate, and heat dissipation fins or topological heat dissipation structures are arranged on the cold plate bottom plate. The cold plate bottom plate is close to the heat-generating components of the server (CPU / GPU / memory, etc.), so as to indirectly transfer the heat of the heat-generating components to the cooling liquid enclosed in the circulation pipeline, and then take away the heat.

[0005] In recent years, there have been many methods to introduce high-thermal-conductivity diamond copper composite materials into liquid cooling structures, but due to the influence of the interface layer, the effect is not very obvious. CN119008551A discloses a diamond-metal composite heat dissipation liquid cooling device. Although diamond-metal composite materials are introduced as a transition heat sink, due to the presence of a heat dissipation base between the diamond-metal composite material and the liquid cooling box, whether it is through welding or bonding, the influence of the intermediate interface layer will lead to a decrease in the heat transfer effect of the diamond-metal transition heat sink. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the purpose of this application is to provide a chip package heat dissipation liquid cooling device with a sandwich structure, ensuring structural stability during the thermal cycle, avoiding failure caused by thermal stress, and solving the problem of poor heat transfer effect of the heat dissipation liquid cooling device.

[0007] To solve the above problems, the technical solutions adopted in this application are as follows: An embodiment of the present application provides a chip package heat dissipation liquid cooling device with a sandwich structure, including a heat dissipation base and a chip soldering table located on the heat dissipation base. The chip soldering table is a sandwich structure composite board with copper layers on the upper and lower surfaces; the chip soldering table is welded to the heat dissipation base.

[0008] As a further preferred solution, the heat dissipation base in the embodiment of the present application is made of a diamond copper composite board with a sandwich structure.

[0009] As a further preferred solution, the diamond metal composite board in the embodiment of the present application is a composite board sintered from a hexahedral metal shell and at least one diamond-metal composite layer placed in the metal shell; the diamond-metal composite layer includes a metal mesh and diamond particles coated with a coating, the diamond particles are arranged in the meshes of the metal mesh, and the voids between the meshes and the diamond particles are filled with metal powder; metal atoms in the metal mesh diffuse towards the diamond surface through the coating to form a mixed transition zone.

[0010] As a further preferred solution, the coating in the embodiment of the present application is a coating formed by one material among Ti, Cr, W, V, Zr or a composite coating formed by two or more materials; the thickness of the coating is 0.1 - 0.5 μm.

[0011] As a further preferred solution, the metal shell, the metal mesh and the metal powder in the embodiment of the present application are made of the same metal material, and the metal material is copper or aluminum.

[0012] As a further preferred solution, the diamond metal composite board in the embodiment of the present application is a composite board with a copper layer-diamond sheet-copper layer sandwich structure composed of a diamond sheet in the middle layer and copper layers on the upper and lower surfaces of the diamond.

[0013] As a further preferred solution, the chip soldering table in the embodiment of the present application is a composite board sintered from a reinforcing material layer in the middle layer and a copper layer coated on the surface of the reinforcing material layer. Specifically, the reinforcing material layer is one of a diamond sheet, alumina ceramic, zirconia-reinforced alumina ceramic, aluminum nitride ceramic, and silicon nitride ceramic.

[0014] As a further preferred solution, the upper surface and the lower surface of the reinforcing material layer in the embodiment of the present application are respectively coated with copper layers, or the six surfaces of the reinforcing material layer are wrapped with copper layers.

[0015] As a further preferred solution, the thickness of the copper layer in the chip soldering table in the embodiment of the present application is 0.1 - 2 mm; the thickness of the metal layer on the upper surface of the diamond metal composite board is 0.1 - 2 mm, and the thickness of the metal layer on the lower surface is 0.2 - 3 mm.

[0016] As a further preferred solution, the chip package heat dissipation liquid cooling device with a sandwich structure described in the embodiments of the present application further includes a liquid cooling box located at the bottom of the heat dissipation base, and a microchannel structure is provided at the bottom of the heat dissipation base; a cavity for accommodating the microchannel structure is provided on the liquid cooling box.

[0017] As a further preferred solution, the microchannel structure described in the embodiments of the present application is a number of fins printed on the bottom of the heat dissipation base by 3D printing, and the material for 3D printing is pure copper powder with a particle size of 10 - 50 μm.

[0018] As a further preferred solution, the height of the fins described in the embodiments of the present application is 2 - 5 mm; the relationship between the fin thickness δ and the pitch S is such that the value of S / δ is 1.5 - 2, and the fin thickness δ is 0.1 - 0.2 mm.

[0019] As a further preferred solution, the chip is welded to the heat dissipation base by brazing, and the solder is one of gold - tin solder, nano - silver paste, micro - silver paste, nano - silver paste, and micro - copper paste.

[0020] As a further preferred solution, the chip package heat dissipation liquid cooling device with a sandwich structure described in the embodiments of the present application can be applied in multiple fields. For example, in the field of high - power laser diodes, it can be used in medical lasers, industrial cutting equipment, etc.; in the field of GaN RF amplifiers, it can be used in 5G base stations, radar systems, etc.; in the field of power electronics modules, it can be used in EV motor control, solar inverters, etc.; in the field of aerospace electronic equipment, it can be used in radar modules, satellite communications, etc.; in the field of high - heat - flux density electronic device processing, it can be used for liquid cooling of AI servers, GPU clusters, and cloud computing and big data centers, as well as manufacturing devices such as 5G / 6G base station GaN RF chips and electric vehicle SiC inverter modules; in the field of high - energy laser systems, it is used for manufacturing fiber laser pump couplers and solid - state laser crystal heat sinks; in the field of nuclear energy and fusion devices, it is used for manufacturing divertor targets and plasma first walls of nuclear fusion reactors, etc.; in the field of special power and energy equipment, it is used for manufacturing IGBT modules of electromagnetic ejection systems, contacts of high - voltage DC circuit breakers, etc.; in the field of aerospace, it is used for the beam spot area of electron beam focusing systems, the periphery of metal 3D printing laser melting pools, etc.; in the field of quantum and superconductivity, it is used for manufacturing microwave resonators for superconducting qubits and room - temperature superconducting power line joints.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The chip soldering table of the chip packaging heat dissipation liquid cooling device with a sandwich structure described in this application uses a sandwich structure composite board with copper layers on the upper and lower surfaces. The copper layers provide good heat conduction paths. At the same time, the intermediate layer can use materials with low coefficient of thermal expansion such as diamond and ceramic to ensure structural stability during the thermal cycle and avoid failure caused by thermal stress.

[0022] 2. In the chip packaging heat dissipation liquid cooling device with a sandwich structure described in this application, further, the heat dissipation base uses a diamond-metal composite board with high thermal conductivity. By combining diamond and metal, the heat dissipation base can quickly conduct the heat generated by the chip to the liquid cooling system. And the diamond-metal composite material and the metal-coated layer with fins are an integral structure, without the need for welding or bonding, and there will be no influence of the intermediate interface layer, significantly reducing the thermal resistance.

[0023] 3. In the chip packaging heat dissipation liquid cooling device with a sandwich structure described in this application, the microchannel structure provided at the bottom of the heat dissipation base increases the heat dissipation area. At the same time, the coolant in the liquid cooling box flows through the microchannels, and can efficiently take away the heat; the design of the microchannel structure makes the heat exchange between the coolant and the heat dissipation base more sufficient, improving the heat transfer efficiency. The cavity provided on the liquid cooling box is used to accommodate the microchannel structure, ensuring that the coolant can completely cover the microchannels and form good thermal contact; avoiding the problems of air gaps or poor coolant flow that may exist in the traditional liquid cooling system, and further improving the heat transfer effect.

[0024] 4. The chip packaging heat dissipation liquid cooling device with a sandwich structure described in this application enables the coolant to quickly take away the heat through the design of the microchannel structure and the liquid cooling box, avoiding the accumulation of heat between the transition heat sink and the liquid cooling box, thereby improving the overall heat dissipation efficiency; the use of the sandwich structure and the diamond-metal composite board improves the structural stability and thermal cycle life of the device, ensuring high-efficiency heat transfer performance during long-term use.

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 Schematic structural diagram of the chip packaging heat dissipation liquid cooling device with a sandwich structure described in Embodiment 1.

[0028] Figure 2 This is the exploded view of the chip package heat dissipation liquid cooling device with a sandwich structure described in Embodiment 1 of the present application.

[0029] Figure 3 This is the schematic diagram of the fin structure described in Embodiment 1 of the present application.

[0030] Figure 4 This is the schematic diagram of the structure of the chip package heat dissipation liquid cooling device described in Comparative Example 1.

[0031] Among them, each reference numeral is: 10, heat dissipation base; 20, chip soldering table; 11, surface copper layer; 12, diamond copper composite layer; 13, bottom copper layer; 21, diamond sheet; 22, second copper layer; 30, liquid cooling box; 31, cavity; 40, microchannel structure; 50, TIM layer; 60, heat sink structure. Detailed implementation manners

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0033] The term "including" and other equivalent descriptive manners involved in the description and claims of the present application are intended to cover non-exclusive inclusion, that is, including both the content clearly described in the description and claims and the steps or units inherent in the product, method, or structure but not described in the description and claims.

[0034] The embodiment of the present application provides a chip packaging heat dissipation liquid cooling device with a sandwich structure, including a heat dissipation base and a chip soldering table located on the heat dissipation base; the chip soldering table is a sandwich structure composite board with copper layers on the upper and lower surfaces, and the copper layers on the upper and lower surfaces can provide good heat conduction paths. The chip packaging heat dissipation liquid cooling device with a sandwich structure described in the embodiment of the present application is applicable to the heat dissipation requirements of high power density chips. In some embodiments, the heat dissipation base adopts a diamond metal composite board with a sandwich structure. By utilizing the extremely high thermal conductivity of diamond, diamond is combined with metal. During chip packaging, the heat generated by the chip can be quickly conducted to the liquid cooling system, reducing the thermal resistance. Further, in some embodiments, a liquid cooling box is provided at the bottom of the heat dissipation base, and a microchannel structure is provided at the bottom of the heat dissipation base to increase the heat dissipation area, so that the heat exchange between the coolant and the heat dissipation base is more sufficient; a cavity for accommodating the microchannel structure is provided on the liquid cooling box. In some embodiments, the chip soldering table is a composite board sintered from a reinforcing material layer located in the middle layer and copper layers coated on the surface of the reinforcing material layer. The reinforcing material layer is selected as a high thermal conductivity insulating material. Compared with traditional PCB materials, the high thermal conductivity insulating material has both high thermal conductivity and good insulation. In the composite material, the copper layer is responsible for conducting electricity and dissipating heat, while the middle reinforcing material provides structural support and insulation. The composite material formed by it and metallic copper can not only prevent current leakage, but also improve the thermal conductivity of the copper composite material.

[0035] In some embodiments of the present application, both the welding platform and the heat dissipation base can be made of a composite material sintered from a hexahedral copper foil shell and at least one layer of diamond-metal composite layer placed in the copper foil shell. This six-sided coating structure forms a dense shell, blocking the penetration of oxygen and water vapor. The wettability between metal and diamond is poor, relying on high-cost coatings and having a high interfacial thermal resistance. The metal foil shell and the internal metal mesh synergistically diffuse during sintering, effectively reducing the interfacial thermal resistance. Due to the large difference in the coefficient of thermal expansion (CTE) between traditional materials and diamond-metal composites, thermal stress cracking is prone to occur. In the embodiments of the present application, the diamond-metal composite layer includes a metal mesh and diamond particles coated with a coating on the surface. The diamond particles are arranged in the grids of the metal mesh, and the voids between the grids and the diamond particles are filled with metal powder. Through this scheme combining the metal mesh skeleton and metal powder filling, the adjustment of the coefficient of thermal expansion can be achieved, making it nearly match the coefficient of thermal expansion of electronic components such as semiconductor chips. The metal foil shell and metal powder filling reduce the sintering temperature, avoid diamond graphitization, reduce energy consumption, and improve the yield. In the embodiments of the present application, during the sintering process, metal atoms in the metal mesh will diffuse through the coating to the surface of the diamond, forming a mixed transition zone. The thermal conductivity of traditional materials is significantly anisotropic and difficult to meet the requirements of directional heat dissipation. In the embodiments of the present application, the metal foil shell and the internal metal mesh-metal powder form a three-dimensional interpenetrating structure, which can effectively improve the thermal conductivity and isotropy of the composite material. Preferably, the metal shell, metal mesh, and metal powder are made of the same metal material, and the metal material is copper or aluminum.

[0036] In the above embodiments, the composite plate sintered from a hexahedral metal shell and at least one layer of diamond-metal composite layer placed in the metal shell is prepared by the following method: Manufacture a hexahedral metal box: First, punch out the developed pattern of a hexahedron from a metal sheet, leaving creases at the edges; fold along the edges to form a hexahedral box, and connect the edges at the joints with a metal adhesive; or use laser cutting or wire cutting to cut out the developed pattern of a hexahedron, pre-engrave creases at the edges; fold along the edges and locally weld at the joints of the edges to combine adjacent edges; obtain a hexahedral copper foil box with a lid and an opening, and place it in a mold; Select a metal mesh: Use a metal mesh with a grid structure of a regular hexahedron or a regular octahedron honeycomb structure. The edge length L of the grid is 10 - 20 μm larger than the particle size D of a single diamond particle; lay the manufactured metal mesh in the above-mentioned hexahedral metal box; Arrange diamond particles: Use an arranging machine to arrange diamond particles coated with a coating on the surface in each grid of the metal mesh; Void filling: Place the hexahedral metal box filled with diamond particles and the mold on a mechanical vibrating table with a vibration frequency of 2 - 10 Hz, a vibration time of 5 - 20 min, and an amplitude of 0.2 - 0.5 mm. Spray copper powder onto the copper mesh under the vibration mode; use electrostatic spraying technology to apply an electric field to direct the metal powder to fill the grid gaps. The electric field voltage is 5 - 10 kV, and the particle size of the metal powder is 0.5 - 5 μm; until the metal powder fills the voids of the metal mesh and reaches the same height as the metal mesh. Multi - layer stacking: After the void filling step, place a metal mesh in the hexahedral metal box, repeat the steps of arranging diamond particles and void filling until the metal mesh is flush with the height of the hexahedral metal box. Cover the upper cover at the opening and integrate the upper cover with the metal box to obtain a pre - form. Sintering and forming: Place the above - mentioned pre - form in a vacuum sintering furnace for sintering to obtain a sintered composite material. In this step, when the metal shell, metal mesh, and metal powder are all made of metal copper, the vacuum degree in the furnace is < 10 Pa, the hot - pressing pressure is 20 - 40 MPa, the sintering temperature is 850 - 920 °C, and the time is 55 - 65 min. When the metal shell, metal mesh, and metal powder are all made of metal aluminum, the vacuum degree in the furnace is < 10 Pa, the hot - pressing pressure is 20 - 40 MPa, the sintering temperature is 520 - 620 °C, and the time is 30 - 50 min.

[0037] In the embodiments of the present application, a sandwich - structured composite board using diamond sheets as the reinforcing material layer is prepared by the following method: Stack copper sheets and diamond sheets in the order of copper - diamond - copper in a mold, and then place the mold in a vacuum sintering furnace for sintering. The vacuum degree in the vacuum hot - pressing furnace is 10 -1 ~10 -3 Pa. Under a hydrogen - argon mixed reducing atmosphere with a hydrogen volume fraction of 5%, heat up to 900 - 1100 °C at a rate of 5 - 20 °C / min, keep the temperature for 80 - 120 min. After the heat - preservation ends, start to apply pressure, the pressure is 20 - 40 MPa, keep the pressure for 10 - 20 min and then cool down.

[0038] Example 1

[0039] As Figures 1-3As shown in the figure, the embodiment of the present application provides a chip package heat dissipation liquid cooling device with a sandwich structure, including a heat dissipation base 10, a chip soldering table 20 located on the heat dissipation base 10, and a liquid cooling box 30 located at the bottom of the heat dissipation base 10. A microchannel structure 40 is provided at the bottom of the heat dissipation base 10; a cavity 31 for accommodating the microchannel structure is provided on the liquid cooling box 30. The heat dissipation base is a sandwich structure composed of a surface copper layer 11, a diamond copper composite layer 12, and a bottom copper layer 13, which is a composite plate sintered from a hexahedral copper foil shell (thickness 250μm) and a diamond-copper composite layer placed in the copper foil shell; the diamond-copper composite layer includes a copper mesh (mesh wall thickness 15μm) and diamond particles coated with a 0.2μm thick metal Ti coating on the surface. The diamond particles are arranged in the meshes of the copper mesh. The plane size of the copper mesh is the same as the inner bottom surface of the copper foil box body, and copper powder is filled in the gaps between the meshes and the diamond particles; Cu atoms in the copper mesh diffuse through the coating to the surface of the diamond to form a mixed transition zone; the chip soldering table is a sandwich structure composite plate with copper layers on the upper and lower surfaces, including a diamond sheet 21 (thickness 0.3mm) and a second copper layer 22 (thickness 1mm) covering the upper and lower surfaces of the diamond sheet 21; the chip soldering table 20 is welded and connected to the heat dissipation base 10 through the second copper layer 22 at the bottom of the chip soldering table and the surface copper layer on the surface of the heat dissipation base.

[0040] In Example 1, the diamond metal composite plate used for the heat dissipation base is prepared by the following method: (1) Punch out the shape of the unfolded hexahedron on a copper foil with a thickness of 250μm, and reserve creases at the edges; bond the edges of the copper foil with the unfolded hexahedron shape with metal adhesive to form a copper foil box body with an upper cover and an open upper surface; place the copper foil box body with an open upper surface into a graphite mold; (2) Use a copper mesh with a regular hexahedron mesh to place diamond particles, with a mesh wall thickness of 15μm. The edge length of the regular hexahedron is 15μm larger than the particle size of the placed diamond particles. The plane size of the copper mesh is the same as the inner bottom surface of the copper foil box body, and then place the copper mesh into the copper foil box body; (3) Use an arrangement machine to arrange artificial CVD diamond particles with a 0.5μm Ti coating on the surface in each mesh of the copper mesh, and the particle size of the diamond particles is 300μm; (4) The copper foil box body arranged with diamond and the graphite mold are placed on a mechanical vibrating table. The vibration frequency of the vibrating table is turned on to be 10 Hz, the vibration time is 10 min, and the amplitude is controlled to be 0.2 mm; the copper powder is a mixed copper powder mixed with nano-Al2O3. Among them, the dosage of nano-Al2O3 accounts for 0.5 wt% of the weight of the copper powder, and the particle size of the copper powder is 3 μm; the electrostatic spraying technology is used to apply an electric field to make the copper powder directionally fill the grid gaps of the copper mesh until the mixed copper powder fills the entire height of the copper mesh, and the electric field voltage is 5 kV; (5) Place the second layer of copper mesh and repeat the above steps (2)-(4); (6) After three layers are stacked, the copper mesh is flush with the height of the copper foil box body, and the copper foil on the upper surface is covered and bonded to obtain a preform; (7) The obtained preform is subjected to vacuum hot pressing sintering. The vacuum degree in the furnace is 1 Pa, the hot pressing pressure is 35 MPa, the sintering temperature is 900 °C, and the time is 60 min; a copper-diamond-copper-copper sandwich structure composite material with a sintered blank formed is obtained.

[0041] The sandwich structure composite board in this embodiment is prepared by the following method: The copper sheet (thickness 0.5 mm) and the diamond sheet (thickness 250 μm) are stacked in the order of copper-diamond-copper in the mold, and then the mold is placed in a vacuum sintering furnace for sintering. The vacuum degree in the vacuum hot pressing furnace is 10 -1 Pa, in a hydrogen-argon mixed reducing atmosphere with a hydrogen volume fraction of 5%, it is heated to 950 °C at a rate of 10 °C / min, held for 90 min, pressurization starts after the holding ends, the pressurization pressure is 30 MPa, and it is cooled after holding the pressure for 15 min.

[0042] Example 2

[0043] This embodiment of the present application provides a chip package heat dissipation liquid cooling device with a sandwich structure, wherein the sandwich structure composite board includes a ceramic material layer (aluminum oxide ceramic, thickness 1 mm) located in the middle layer and a copper layer (thickness 0.8 mm) wrapped on the surface of the ceramic material layer; other features are the same as those in the above Example 1.

[0044] Example 3

[0045] An embodiment of the present application provides a chip package heat dissipation liquid cooling device with a sandwich structure, which includes a heat dissipation base, a chip soldering table located on the heat dissipation base, and a liquid cooling box located at the bottom of the heat dissipation base. A microchannel structure is provided at the bottom of the heat dissipation base; a cavity for accommodating the microchannel structure is provided on the liquid cooling box. The heat dissipation base is a diamond copper composite plate, and the diamond copper composite plate includes a diamond sheet (with a thickness of 0.5 mm) in the middle layer and a copper layer (with a thickness of 0.3 mm) coated on the surface of the diamond sheet, that is, a copper-diamond-copper composite plate; the chip soldering table is a sandwich structure composite plate with copper layers on the upper and lower surfaces, and the sandwich structure composite plate adopts the same copper-diamond-copper composite plate as the heat dissipation base; the chip soldering table and the heat dissipation base are welded and connected through the copper layer at the bottom of the chip soldering table and the copper layer on the surface of the heat dissipation base.

[0046] Example 4

[0047] An embodiment of the present application provides a chip package heat dissipation liquid cooling device with a sandwich structure. The chip soldering table adopts a sandwich structure composite plate, and the sandwich structure composite plate includes an alumina (Al2O3) ceramic layer (with a thickness of 0.6 mm) in the middle layer and a copper layer (with a thickness of 0.6 mm) wrapped on the surface of the alumina (Al2O3) ceramic, forming a copper-alumina ceramic-copper structure; other features are the same as those in the above Example 3.

[0048] According to the structures listed in the above-mentioned Embodiments 1-4 of the chip soldering platform of the present application, in the sandwich structure composite board, the intermediate layer can be replaced among ceramic materials such as diamond wafers, alumina (Al2O3) ceramics, zirconia toughened alumina (ZTA), aluminum nitride (AlN), and silicon nitride (Si3N4). When using a diamond wafer as the reinforcing material layer, due to its ultra-high in-plane thermal conductivity, the heat generated by the chip can be quickly laterally diffused to the copper layer, avoiding local heat accumulation; the high hardness characteristic of diamond can absorb the thermal expansion mismatch stress between the copper layer and the chip, reducing the risk of interface delamination; it mainly exhibits the effects of ultra-high heat flux diffusion and high-frequency insulation. When using alumina (Al2O3) ceramics as the reinforcing material layer, a stable insulating layer is formed between the copper layer and the chip, and while improving the thermal conductivity, the cost can be effectively reduced; it mainly exhibits the effect of low-cost heat dissipation. When using zirconia toughened alumina (ZTA) as the reinforcing material layer, since the thermal expansion coefficient of zirconia toughened alumina (ZTA) is close to that of copper, the warping of the copper layer caused by thermal cycling can be reduced, enhancing the fracture toughness and the peel strength between layers; its main function is thermal deformation suppression. When using aluminum nitride (AlN) as the reinforcing material layer, its thermal conductivity and thermal expansion coefficient are perfectly matched with silicon / silicon carbide chips, greatly reducing the thermal stress, and the synergistic optimization of high frequency and high heat can be achieved. When using silicon nitride (Si3N4) as the reinforcing material layer, it can adapt to the oxidation of the low copper layer in extreme environments, and is mainly used for extreme environment bearing and corrosion-resistant packaging.

[0049] Based on the above-mentioned Embodiments 1-4, further, in some embodiments of the present application, the coating is a coating formed of one material among Ti, Cr, W, V, Zr or a composite coating formed of two or more materials; the thickness of the coating is 0.1-0.5 μm. In some embodiments, Ti is used as the target, and a dense layer is formed on the diamond surface by magnetron sputtering, and a TiC phase is generated at the interface, with a thickness of about 100 nm. In some other embodiments, the Ti and Cr targets are sputtered simultaneously to achieve an atomic-level hybrid coating to improve the interface shear strength. In still other embodiments, a composite layer of several materials can be used. For example, a Cr layer (0.2-0.3 μm) is first formed on the diamond particle surface by magnetron sputtering, and then a W layer (0.1-0.2 μm) is formed on the surface of the Cr layer. In some embodiments, it can be set as a Ti-Zr-Cu gradient coating, that is, the bottom layer is a 0.1-0.2 μm Ti layer, which reacts with the diamond at the interface to generate TiC to enhance the bonding; the intermediate layer is a 0.1-0.2 μm Zr layer, and the high melting point of the intermediate layer is used to achieve the transition of the thermal expansion coefficient; the surface layer is a 0.2-0.3 μm Cu layer to optimize the wettability of the diamond surface. In addition to the above several implementation methods, it can also be Ti / V alternating deposition, with each layer having a thickness of 20-50 nm and the total thickness of the coating being 0.5 μm.

[0050] Further, based on the solutions of the above Embodiments 1-4, considering the requirements of chips with different powers, preferably, the thickness of the chip soldering table is 0.5-10 mm. For example, a thinner soldering table can be used for low-power chips to reduce thermal resistance; while a thicker one can be used for high-power chips to increase structural stability. The thickness of the heat dissipation base is 8-10 mm; wherein, the thickness of the copper layers on the upper and lower surfaces of the sandwich structure composite board is 0.1-2 mm to optimize soldering wettability and reduce interface resistance; the thickness of the copper layer on the upper surface of the diamond copper composite board is 0.1-2 mm to provide brazing compatibility and inhibit diamond-copper interface cracks; the thickness of the copper layer on the lower surface of the diamond copper composite board is 2-3 mm to enhance the stiffness of the microchannel structure, resist fluid impact, and avoid uneven flow caused by the collapse of the flow channel. The length and width dimensions of the chip soldering table and the heat dissipation base are adjustable according to the size of the embedded device to ensure good adaptability and heat dissipation effect. As Figure 3 shown, based on the above embodiments, a further preferred solution is that the microchannel structure is a number of fins printed on the bottom of the heat dissipation base by 3D printing. Without increasing the size of the cold plate, the heat transfer and system heat dissipation capabilities of the liquid cooling device are effectively improved. The material for 3D printing is pure copper powder with a particle size of 10-50 μm. Since the fin material is the same as the copper layer material at the bottom of the heat dissipation base, there is no need for welding or bonding, and there will be no influence of the intermediate interface layer. The shape of the fins can be selected according to the requirements for heat dissipation effect. For example, conventional straight fins can be selected, or wavy fins, needle / column fins, fractal tree-like fins, etc. can be used. The height of the fins affects the thermal boundary layer and heat transfer area. To balance the thermal efficiency and pressure drop and at the same time adapt to the manufacturing of the microchannels, in some embodiments, the height of the fins is 2-5 mm; in the embodiments of the present application, the liquid cooling method is adopted for cooling. To avoid jet impingement failure, the relationship between the fin thickness δ and the spacing S between adjacent fins is S / δ = 1.5-2, and the fin thickness δ is 0.1-0.2 mm. When the fin thickness and spacing are within this range, the heat exchange efficiency between the thermal boundary layer on the fin surface and the flow core region is the highest. In the present application, to achieve the welded connection between the chip soldering table and the heat dissipation base, a brazing welding method is adopted, and the solder for brazing welding can be selected from, but not limited to, one of gold-tin solder, nano / micro silver paste, and nano / micro copper paste. Since gold-tin solder has high thermal conductivity, low melting point, good mechanical strength, a small wetting angle of gold-tin on the copper surface, and micron-level precise welding can be achieved through local heating; and the thickness of the gold-tin solder layer has strong compressibility, which can effectively reduce interface delamination caused by thermal expansion mismatch and can also prevent the 3D-printed fins from deforming at high temperatures. Although the unit price of gold-tin solder is 8-10 times that of tin-silver-copper, due to the improved reliability, the repair rate is greatly reduced. Therefore, in the preferred embodiments, gold-tin solder is mainly used to weld the chip soldering table and the heat dissipation base.

[0051] In an embodiment of the present application, in order to improve the heat exchange efficiency, the liquid cooling box is made of materials such as copper plates, aluminum plates, stainless steel plates, and heat pipes. A fluid inlet end and a fluid outlet end are provided on the liquid cooling box.

[0052] Embodiment 5

[0053] An embodiment of the present application provides a chip package heat dissipation liquid cooling device with a sandwich structure, including a heat dissipation base, a chip soldering table located on the heat dissipation base, and a liquid cooling box located at the bottom of the heat dissipation base. A microchannel structure is provided at the bottom of the heat dissipation base; a cavity for accommodating the microchannel structure is provided on the liquid cooling box. The heat dissipation base is a sandwich structure composed of a surface aluminum layer, a diamond-aluminum composite layer, and a bottom aluminum layer, and is a composite plate sintered from a hexahedral aluminum foil shell and a diamond-aluminum composite layer placed in the aluminum foil shell; the diamond-aluminum composite layer includes an aluminum mesh and diamond particles coated with a coating on the surface, and the diamond particles are arranged in the grids of the copper mesh, and aluminum powder is filled in the gaps between the grids and the diamond particles; Cu atoms in the aluminum mesh diffuse towards the diamond surface through the coating to form a mixed transition zone; the chip soldering table is a sandwich structure composite plate with copper layers on the upper and lower surfaces, including a diamond sheet and aluminum layers covering the upper and lower surfaces of the diamond sheet; the chip soldering table and the heat dissipation base are welded and connected through the aluminum layer at the bottom of the chip soldering table and the surface aluminum layer of the heat dissipation base.

[0054] The sandwich structure composed of the surface aluminum layer, the diamond-aluminum composite layer, and the bottom aluminum layer adopted in the above Embodiment 5 is prepared by the following method.

[0055] (1) Punch out the shape of the unfolded hexahedron on an aluminum foil with a thickness of 300 μm, and reserve creases at the edges; bond the edges of the copper foil with the shape of the unfolded diagram with a metal adhesive to form an aluminum foil box body with an upper cover and an open upper surface; place the aluminum foil box body with an open upper surface into a graphite mold; (2) Use an aluminum mesh with a regular hexahedron grid to place diamond particles. The grid wall thickness is 20 μm, and the edge length of the regular hexahedron is 10 μm larger than the particle size of the placed diamond particles. The plane size of the aluminum mesh is the same as the inner bottom surface of the aluminum foil box body, and then place the aluminum mesh into the aluminum foil box body; (3) Use a placement machine to arrange artificial CVD diamond particles with a 0.5 μm Ti coating on the surface in each grid of the copper mesh, and the particle size of the diamond particles is 200 μm; (4) The aluminum foil box body arranged with diamond and the graphite mold are placed on a mechanical vibration table. The vibration frequency of the vibration table is turned on to be 10 Hz, the vibration time is 10 min, and the amplitude is controlled to be 0.2 mm. The electrostatic spraying technology is used to apply an electric field to direct the filling of aluminum powder (with a particle size of 3 μm) into the grid gaps of the aluminum mesh until the mixed aluminum powder fills the entire height of the aluminum mesh. The electric field voltage is 5 kV. (5) Place the second layer of aluminum mesh and repeat the above steps (3) and (4). (6) Perform the superposition of aluminum mesh layers until the aluminum mesh is flush with the height of the aluminum foil box body, and cover and bond the aluminum foil on the upper surface to obtain a preform. (7) Vacuum hot press sinter the preform. The vacuum degree in the furnace is 1 Pa, the hot press pressure is 60 MPa, the sintering temperature is 900 °C, and the time is 60 min. A composite material of an aluminum-diamond-aluminum-aluminum sandwich structure with a sintered blank formed is obtained.

[0056] The sandwich structure composite board in this Example 5 is prepared by the following method: Stack aluminum sheets (with a thickness of 1 mm) and diamond sheets (with a thickness of 250 μm) in the order of aluminum sheet - diamond - aluminum sheet in a mold, and then put the mold into a vacuum sintering furnace for sintering. The vacuum degree in the vacuum hot press furnace is 10 -1 Pa. Under a hydrogen-argon mixed reducing atmosphere with a hydrogen volume fraction of 5%, heat up to 600 °C at a rate of 10 °C / min, keep warm for 60 min. After the heat preservation ends, start to apply pressure. The applied pressure is 35 MPa, and cool down after holding the pressure for 15 min.

[0057] Preferably, on the basis of the scheme of the above Example 5, the diamond sheet in the middle layer of the sandwich structure composite board can be replaced with ceramic materials such as alumina (Al2O3) ceramics, zirconia toughened alumina (ZTA), aluminum nitride (AlN), silicon nitride (Si3N4), etc.

[0058] Comparative Example 1

[0059] As Figure 4 shown, in this comparative example, a chip package heat dissipation liquid cooling device is provided, including a liquid cooling box (not shown in the figure), a heat dissipation base 10, a chip soldering platform 20 located on the heat dissipation base 10, a TIM layer 50 located on the bottom surface of the heat dissipation base 10, and a heat sink structure 60 located below the TIM layer. A plurality of fins are provided below the heat sink structure. The liquid cooling box is located below the heat sink structure, and a cavity for accommodating the fins is provided on the liquid cooling box. The chip soldering platform is a ceramic copper composite material, including a ceramic substrate and copper layers located on the upper and lower surfaces of the ceramic substrate. The heat dissipation base is a copper base. The heat dissipation base and the chip soldering platform are connected by welding.

[0060] Performance Test

[0061] Perform performance test comparisons on the heat sinks described in the above Examples 1-5 and Comparative Example 1; among them, the thickness of the chip soldering table is set to 5 mm, and the thickness of the copper layers on the upper and lower surfaces of the chip soldering table is 1 mm. In Examples 1-6, the thickness of the heat dissipation base is 8 mm, where the thickness of the copper layer on the upper surface is 1 mm, the thickness of the copper layer on the lower surface is 2.5 mm, the height of the fins is 3 mm, the thickness is 0.1 mm, and the fin pitch is 0.2 mm. In Comparative Example 1, the thickness of the copper plate of the heat dissipation base is 6 mm. Use "chip junction temperature" to characterize the heat dissipation effect of the overall structure, and use ANASY to compare and simulate the heat dissipation effects of different heat dissipation structures on high heat flux density GaN chips. Set the heat flux density of high-power GaN chips to 400 W / cm 2 . The test results are shown in Table 1.

[0062] Table 1: Performance test results

[0063] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. A chip package heat dissipation liquid cooling device with a sandwich structure, comprising a heat dissipation base and a chip soldering table located on the heat dissipation base, characterized in that, The chip soldering table is a sandwich - structured composite board with copper layers on its upper and lower surfaces. The heat dissipation base is made of a diamond - metal composite board with a sandwich structure. The chip soldering table is welded to the heat dissipation base. The diamond - metal composite board is a composite board sintered from a hexahedral metal shell and at least one diamond - metal composite layer placed in the metal shell. The diamond - metal composite layer includes a metal mesh and diamond particles with a coating on the surface. The diamond particles are arranged in the meshes of the metal mesh, and the voids between the meshes and the diamond particles are filled with metal powder. Metal atoms in the metal mesh diffuse through the coating to the diamond surface to form a mixed transition zone.

2. The liquid-cooling device for heat dissipation of a chip package with a sandwich structure according to claim 1, wherein The coating is a coating formed by one of the materials Ti, Cr, W, V, Zr or a composite coating formed by two or more of these materials. The thickness of the coating is 0.1 - 0.5 μm.

3. The chip package heat dissipation liquid cooling device with a sandwich structure according to claim 1, characterized in that, The metal shell, the metal mesh and the metal powder are made of the same metal material, and the metal material is copper or aluminum.

4. The liquid-cooling device for heat dissipation of the chip package with a sandwich structure according to claim 1, characterized in that, The diamond - metal composite board is a composite board with a copper layer - diamond sheet - copper layer sandwich structure composed of a diamond sheet in the middle layer and copper layers on the upper and lower surfaces of the diamond.

5. The liquid-cooling device for heat dissipation of a chip package with a sandwich structure according to claim 1, characterized in that, The chip soldering table is a composite board sintered from a reinforcing material layer in the middle layer and a copper layer coated on the surface of the reinforcing material layer.

6. The liquid-cooling device for heat dissipation of a chip package with a sandwich structure according to claim 5, wherein, The reinforcing material layer is one of diamond sheets, alumina ceramics, zirconia - reinforced alumina ceramics, aluminum nitride ceramics, and silicon nitride ceramics.

7. The chip package heat dissipation liquid cooling device with a sandwich structure according to claim 6, characterized in that, The upper and lower surfaces of the reinforcing material layer are respectively coated with copper layers, or all six surfaces of the reinforcing material layer are wrapped with copper layers.

8. The chip package heat dissipation liquid cooling device with a sandwich structure according to claim 1, characterized in that, In the sandwich - structured composite board, the thickness of the copper layers on the upper and lower surfaces is 0.1 - 2 mm. The thickness of the metal layer on the upper surface of the diamond - metal composite board is 0.1 - 2 mm, and the thickness of the metal layer on the lower surface is 0.2 - 3 mm.

9. The liquid-cooling device for heat dissipation of a chip package with a sandwich structure according to any one of claims 1-8, characterized in that, It also includes a liquid - cooling box at the bottom of the heat dissipation base. A micro - channel structure is provided at the bottom of the heat dissipation base. A cavity for accommodating the micro - channel structure is provided on the liquid - cooling box.

10. The liquid-cooling device for heat dissipation of a chip package with a sandwich structure according to claim 9, wherein, The micro - channel structure is a number of fins printed on the bottom of the heat dissipation base by 3D printing. The material for 3D printing is pure copper powder with a size of 10 - 50 μm.

11. The liquid-cooling device for heat dissipation of a chip package with a sandwich structure according to claim 10, wherein, The height of the fins is 2 - 5 mm. The relationship between the fin thickness δ and the pitch S is that the value of S / δ is 1.5 - 2, and the fin thickness δ is 0.1 - 0.2 mm.

12. The chip package heat dissipation liquid cooling device with a sandwich structure according to claim 1, characterized in that, The chip soldering table and the heat dissipation base are welded by brazing, and the solder used for brazing is one of gold - tin solder, nano - silver paste, micro - silver paste, nano - copper paste, and micro - copper paste.

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