Reinforced semi-immersed liquid cooling heat dissipation board card

Abstract

The invention discloses a reinforced semi-immersed liquid cooling heat dissipation board card. The board card comprises a cold plate with an immersion cavity, a printed board assembly in partition layout and a sealing system. An annular sealing groove is formed in the edge of the cold plate immersion cavity, and a baffle is arranged between the liquid inlet and the liquid outlet to force cooling liquid to flow through the high-power-consumption device. The printed board assembly is glued and fixed by a pressing plate through epoxy resin, the high-power-consumption device is located in the immersion cavity, and the tail electric connector is exposed; the D-shaped sealing strip is embedded in the sealing groove and is pressed and sealed by the distributed screw; the liquid inlet connector, the liquid outlet connector and the overflow valve are installed at the front end of the cold plate in an inwards-concave mode, and the overflow valve is provided with a 1 bar pressure-resistant value for overpressure relief. The design realizes targeted heat dissipation of components and parts (temperature rise at 360W power consumption is less than or equal to 55 DEG C), is compatible with a standard electric connector, meets the size standard of a marine 6U reinforcing module, and is suitable for severe environments such as salt mist and vibration.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic component heat dissipation, and in particular to a reinforced semi-immersed liquid cooling heat dissipation board. Background Art

[0002] Electronic components are continuously evolving toward higher levels of integration and miniaturization, significantly improving performance and dramatically increasing heat flux. However, the heat generated by these components during operation cannot be effectively reduced. The resulting significant temperature rise, if not effectively suppressed, will impact component lifespan and severely restrict overall equipment performance and reliability. Furthermore, with this significant increase in heat dissipation, user requirements for equipment noise levels are also increasing. Therefore, cooling measures that reduce component / equipment temperatures by increasing fan airflow are no longer suitable. This is particularly true in defense computer engineering applications, which primarily utilize fully enclosed, ruggedized equipment. Managing the heat dissipation of high-power components / equipment while maintaining low noise levels has become a pressing issue in this field. Ruggedized board modules, as the fundamental components installed in ruggedized electronic equipment, are a key breakthrough in finding solutions.

[0003] In marine air-cooled reinforced equipment, the heat dissipation method for components on the module is to fit the components to the module cold plate so that the heat is transferred to the cold plate, and then transferred to the chassis through the two ends of the cold plate. Finally, the heat is transferred to the external air through the chassis fan. The disadvantage of this solution is that there are many transmission levels, the total conduction thermal resistance is large, and the heat dissipation efficiency is low. It is necessary to sacrifice the equipment noise index (replacing the high-air-volume fan) to improve the heat dissipation efficiency. There are two options for heat dissipation of modules in marine liquid-cooled reinforced equipment: one is to use a liquid-cooled chassis + conventional cold plate. The components and the module cold plate are fitted together to transfer heat to the cold plate, and then transfer it to the chassis through the two ends of the cold plate. Finally, the heat is transferred to the outside through the coolant flowing through the chassis. This solution can slightly reduce the conduction thermal resistance and use the fluidity of the coolant to improve the heat dissipation efficiency of the equipment, but the efficiency improvement is limited. The second is to use a conventional chassis + a penetrating liquid cooling board module. A flow channel is designed in the module cold plate. The heat of the components is first transferred to the cold plate, and then transferred to the outside through the coolant flowing through the cold plate. This solution can further reduce the conduction thermal resistance and improve the heat dissipation efficiency of the equipment.

[0004] Currently, there's a more efficient cooling method: full immersion liquid cooling. This technology has rarely been reported in the defense reinforcement field, but it's gradually gaining commercial application. This technology requires immersing all modules in a coolant and is commonly used in large data centers with power outputs of tens or even hundreds of kilowatts. However, its drawbacks include high requirements for protective processes for printed circuit boards and electrical connectors, the need for large quantities of coolant, and high overall costs. Furthermore, using it in equipment with power outputs exceeding several hundred watts is a waste of energy and cost. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to propose a reinforced semi-immersed liquid-cooled heat dissipation board card, which is between the penetrating liquid cooling board card and the fully immersed board card, and has the characteristics of wide application range of air-cooled board cards and high heat dissipation efficiency of immersed board cards. The advantage is that the size fully meets the design standards of the marine 6U reinforced module, and only the devices on the printed circuit board are immersed in the coolant in a targeted manner, which can effectively solve the heat dissipation problem of high-heat flux components of the hundred-watt level; at the same time, the electrical connector is exposed to the air, and is not restricted by the compatibility of the coolant or the protection process. A variety of electrical connectors such as CPCI, CPCI-E, VPX, etc. can be used, which has a wider range of applications and is suitable for various reinforced electronic equipment with liquid cooling systems. It can be applied to many fields such as navigation, power plants, field operations, and chemical industry.

[0006] In order to solve the above problems, the present invention provides a reinforced semi-immersed liquid cooling heat dissipation board, comprising:

[0007] The cold plate is provided with an immersion chamber and connected liquid inlet, outlet and overflow holes; an annular sealing groove is provided on the edge of the immersion chamber, and a baffle is provided between the liquid inlet and outlet holes to guide the coolant to the immersion chamber;

[0008] The printed circuit board assembly includes a stacked printed circuit board and a pressure plate; the power consumption device on the top surface of the printed circuit board is located in the immersion cavity, the device on the bottom surface is located outside the immersion cavity, and the tail is provided with an exposed electrical connector; the pressure plate is fixed to the printed circuit board by an adhesive;

[0009] A sealing strip is embedded in the sealing groove and is compressed between the cold plate and the printed circuit board assembly to seal the immersion cavity;

[0010] A fastening screw assembly passes through the printed circuit board assembly and is locked in the screw hole of the cold plate;

[0011] The liquid inlet connector, liquid outlet connector and overflow valve are connected to the liquid inlet hole, liquid outlet hole and overflow hole respectively, and the three are installed in a concave manner at the front end of the cold plate;

[0012] Structural relationship:

[0013] The printed circuit board assembly covers the immersion cavity and forms a closed cavity with the sealing strip and cold plate;

[0014] The coolant flows into the immersion chamber from the liquid inlet connector, flows through the high power consumption components, and then flows out from the liquid outlet connector;

[0015] The overflow valve is located at the end of the coolant flow channel and is used for overpressure relief.

[0016] Preferably, the layout of components on the printed circuit board is as follows: high-power consumption components are concentrated in the area corresponding to the liquid inlet, low-power consumption components are arranged in the area corresponding to the liquid outlet, and no components are placed in the area covered by the pressure plate.

[0017] Preferably, the pressing plate is a carbon fiber plate with a thickness of 2 mm, and its contact surface with the printed circuit board is roughened by grinding with 400-grit sandpaper, and bonded with 3MDP420 epoxy resin glue and thermally cured at 80-120° C. for 24 hours.

[0018] Preferably, it also includes reinforced heat dissipation fins bonded to the surface of the high power consumption device, and the direction of the fins is consistent with the flow direction of the coolant.

[0019] Preferably, the base material of the cold plate is 6063-T5 aluminum alloy, which is milled to form an immersion cavity and a baffle, and the surface is anodized black. The size of the cold plate is 233.2 mm long × 141.4 mm wide, and the thickness is adapted to the 4HP marine reinforcement module standard.

[0020] Preferably, the baffle is located between the liquid inlet and the liquid outlet, 15 mm away from the edge of the immersion chamber, and is used to force the coolant to flow through all high-power consumption components.

[0021] Preferably, the overflow valve pressure value is manually adjusted to 1 bar, and the coolant is automatically discharged when the internal pressure of the immersion chamber is greater than 1 bar; the coolant is 3M Novec fluorinated liquid, which has insulation properties and compatibility with adhesives / sealing materials.

[0022] Preferably, the sealing strip is a D-shaped cross-section sealing member, which is installed in an annular sealing groove with a width of 2.6 mm and a depth of 1.8 mm.

[0023] Preferably, the electrical connector is compatible with CPCI, CPCI-E or VPX standards, and the surface of the printed circuit board assembly is coated with TS96-11 fluoropolyurethane triple-conformal coating.

[0024] Preferably, the screw holes are distributed along the periphery of the cold plate, with a spacing of ≤35 mm.

[0025] The advantages of the present invention compared with the prior art are:

[0026] 1. The dimensions of the present invention adopt the design standard of 6U reinforced modules for ships. The cold plate size is 233.2×141.4 (length×width, unit: mm), and the thickness is the thickness of a standard 4HP module. It only occupies a single slot in the chassis and has good universality. It can be used for ship-based reinforced electronic equipment using standard 6U modules.

[0027] 2. The printed circuit board of this invention utilizes a centralized component layout, with components arranged on both sides of the board. This layout creates an immersion cavity and flow channels, ensuring that all devices requiring heat dissipation are located within the immersion cavity. The immersion cavity can be designed and modified based on actual usage requirements.

[0028] 3. In the present invention, the cold plate, the press plate and the printed circuit board are assembled to form an immersion cavity into a closed cavity, and the sealing of the closed cavity is ensured by glue sealing, using sealing strips and screw mounting.

[0029] 4. In the present invention, a liquid inlet and a liquid outlet are provided, and a complete flow channel heat dissipation path is constructed in combination with the flow channel. The liquid inlet / outlet is located at the front end of the cold plate to ensure that there is sufficient space at the rear of the printed circuit board for the layout of electrical connectors to meet different usage requirements.

[0030] 5. In this invention, a relief valve is installed at the front end of the cold plate. The pressure resistance value of the relief valve can be manually adjusted. The pressure resistance value of this device is set to 1 bar. When the internal pressure of the module exceeds 1 bar, the coolant flows out from the relief valve to ensure the safety and reliability of the equipment.

[0031] 6. In the present invention, the coolant used is 3MNovec fluorinated liquid coolant, which is relatively low in cost, has good insulation properties, and is non-toxic. It will not cause short circuits in the components on the printed circuit board in the module, and will not corrode the cold plate structure. After the coolant overflows from the overflow valve, it will not cause pollution or short circuit risks inside the chassis.

[0032] 7. The present invention's heat dissipation path is as follows: coolant enters through the liquid inlet, flows through the heat dissipation device, absorbs heat, and transfers the heat to the cooling system through the liquid outlet. This provides a more direct and rapid heat dissipation effect than a through-the-air cold plate. Furthermore, for devices with high heat dissipation / heat flux density, auxiliary heat dissipation fins are installed within the cavity to increase the device's heat dissipation area, thereby achieving even better heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a schematic diagram of the three-dimensional structure of the heat dissipation board of the present invention;

[0035] Figure 2 This is a schematic diagram of the exploded structure of the heat dissipation board of the present invention;

[0036] Figure 3 Schematic diagram of the three-dimensional structure of the printed circuit board assembly of the present invention;

[0037] Figure 4 Schematic diagram of the three-dimensional structure of the cold plate in the present invention;

[0038] In the figure: 1-cold plate; 2-sealing strip; 3-pressing plate; 4-reinforced heat sink fin; 5-fastening screw assembly; 6-printed circuit board; 7-liquid inlet connector; 8-liquid outlet connector; 9-overflow valve; 10-electrical connector; 11-liquid inlet hole; 12-liquid outlet hole; 13-overflow hole; 14-sealing strip mounting groove; 15-immersion chamber; 16-screw mounting hole. DETAILED DESCRIPTION

[0039] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0041] In order to more clearly illustrate the specific implementation of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0042] 1) The diagram of the reinforced semi-immersed liquid cooling board is as follows Figure 1 As shown, components on the top surface of the printed circuit board (PCB) requiring heat dissipation are enclosed within a submerged cavity on the board's cold plate, which is filled with coolant. The bottom surface of the PCB and the electrical connectors for external connections are not enclosed and are exposed to the air, creating a semi-submerged cooling system. The board's inlet / outlet connectors and relief valve are recessed, ensuring the overall board dimensions are 233.2 x 141.4 (length x width) and a height of 4HP. The inlet and outlet connectors are located at the front of the module, free from space for electrical connectors. This ensures that the board's dimensions and electrical connectors fully comply with the dimensional standards for marine ruggedized 6U boards, making it suitable for marine ruggedized electronic equipment using standard 6U modules.

[0043] 2) The schematic diagram of the printed circuit board assembly is as follows Figure 3As shown, it is mainly composed of a pressing plate 3, reinforced heat dissipation fins 4, and a printed circuit board 6. The pressing plate 3 and the printed circuit board 6 are assembled by gluing. Among them, the base material of the printed circuit board 6 adopts FR4-Tg170, a high moisture resistance and high bending strength base material. Except for the screw fixing holes, no other vias are set to ensure that the coolant will not overflow from the printed circuit board. The components are divided into two areas according to their functions. The high-power consumption components are arranged in the liquid inlet area and the low-power consumption components are arranged in the liquid outlet area. This ensures that the coolant dissipates heat to the high-power consumption components first, and no components are placed in the contact area with the pressing plate. The electrical connector 10 is welded on the printed circuit board. Since the electrical connector is arranged outside the immersion cavity, there is no special requirement for its protection process. The connector can use a variety of electrical connectors such as CPCI, CPCI-E, VPX, etc. to meet the use requirements of various environments and occasions. Platen 3 is constructed from a 2mm-thick carbon fiber sheet milled into shape. After milling, the contact surface with the printed circuit board (PCB) is roughened with 400-grit sandpaper. After polishing, it is cleaned with alcohol or acetone and dried. The roughened surface strengthens the bond between the platen and the PCB. The use of carbon fiber leverages its high strength to act as a reinforcing framework, enhancing the PCB's strength and meeting the requirements of high-vibration environments. Secondly, its insulating properties prevent component short circuits that could occur with a metal framework during assembly. After forming, the PCB and platen are bonded together using 3MDP420 epoxy resin adhesive as shown in the diagram. The adhesive is heat-cured for 24 hours at 80-120°C to secure the connection. This adhesive offers high strength, excellent sealing, and good compatibility with fluorinated fluids. After assembly, the PCB assembly is treated with TS96-11 fluorourethane varnish for three-component protection, further enhancing its protective properties. For high-power components, four reinforced heat sink fins are applied and glued to the surface of the component using epoxy resin glue. The direction of the fins is consistent with the direction of the flow channel. The fins are used to expand the external heat conduction area of ​​the component and enhance the heat conduction efficiency of the coolant to the high-power components.

[0044] 3) The cold plate diagram of the board is as follows Figure 4As shown. The base material of the cold plate is made of 6063-T5 aluminum alloy to ensure the strength and corrosion resistance of the entire board. According to the arrangement area of ​​the device, the immersion cavity 15 is machined by milling, and the liquid inlet hole 11, the liquid outlet hole 12 and the overflow hole 13 are respectively machined by using a straight hole drill. During milling, a baffle is reserved at a position 15mm away from the liquid inlet and outlet holes to force the coolant to flow through all components to avoid short circuit of the heat dissipation channel. At 1.2mm around the immersion cavity 15, a 2.6×1.8 (width×depth, unit mm) 14 sealing strip mounting groove is machined for assembling the sealing strip 2, and screw mounting holes 16 are machined around the outer periphery of the groove, with the screw hole spacing not exceeding 35mm. After processing, the cold plate is cleaned with deionized water to avoid residue. After cleaning, the cold plate is anodized and black-plated for final formation.

[0045] 4) The composition of the reinforced semi-immersed liquid cooling heat dissipation board is as follows: Figure 2 As shown. It mainly consists of a cold plate 1, a sealing strip 2, a pressure plate 3, a reinforced heat dissipation fin 4, a fastening screw assembly 5, a printed circuit board 6, a liquid inlet connector 7, a liquid outlet connector 8 and a relief valve 9. When assembling, ① install the sealing strip: install the D-shaped sealing strip in the sealing strip installation groove 14; ② install the printed circuit board assembly: use it on the assembled printed circuit board assembly ( Figure 3 ) Tighten the sealing strip 2 and use the fastening screw assembly 5 to fasten the printed circuit board assembly to the cold plate; ③ Install the connector: Install the liquid inlet connector 7, liquid outlet connector 8 and overflow valve 9 on the cold plate, adjust the overflow valve pressure to 1 bar, and ensure that when the internal pressure of the board exceeds 1 bar, the coolant overflows from the overflow valve to avoid equipment failure caused by deformation of the board or printed circuit board due to excessive pressure; ④ Liquid injection: After the first three steps, the immersion chamber is completely sealed. Keep the board upright and inject 3MNovec fluorinated liquid coolant into the immersion chamber through the liquid inlet connector 7. During liquid injection, ensure that the liquid outlet connector 8 is always open until the coolant overflows, ensuring that all air in the immersion chamber is exhausted; ⑤ Install accessories: Install locking strips, pullers and other accessories to complete the assembly of the entire board.

[0046] Finally, all parts not fully described in the present invention adopt mature products and mature technical means in the existing technology.

[0047] The above description of the present invention and its embodiments is non-limiting. The drawings illustrate only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by the above, and does not deviate from the purpose of the present invention, without inventive design, a structure and embodiment similar to the technical solution should fall within the scope of protection of the present invention.

Claims

1. A reinforced semi-immersed liquid cooling heat dissipation board, characterized in that: include: A cold plate (1), wherein the cold plate (1) is provided with an immersion chamber (15) and a liquid inlet hole (11), a liquid outlet hole (12) and an overflow hole (13) that are connected to each other; an annular sealing groove (14) is provided on the edge of the immersion chamber (15), and a baffle is provided between the liquid inlet hole (11) and the liquid outlet hole (12) to guide the cooling liquid to the immersion chamber; A printed circuit board assembly comprises a stacked printed circuit board (6) and a pressure plate (3); power consumption components requiring heat dissipation on the top surface of the printed circuit board (6) are located within an immersion cavity (15), components not requiring heat dissipation on the bottom surface are located outside the immersion cavity, and an exposed electrical connector (10) is provided at the rear end; the pressure plate (3) is fixed to the printed circuit board (6) by an adhesive; A sealing strip (2) is embedded in the sealing groove (14) and is pressed between the cold plate (1) and the printed circuit board assembly to seal the immersion cavity; A fastening screw assembly (5) passes through the printed circuit board assembly and is locked in a screw hole (16) of the cold plate (1); The liquid inlet connector (7), the liquid outlet connector (8) and the overflow valve (9) are respectively connected to the liquid inlet hole (11), the liquid outlet hole (12) and the overflow hole (13), and the three are concavely installed at the front end of the cold plate; Structural relationship: The printed circuit board assembly covers the immersion cavity (15) and forms a closed cavity with the sealing strip (2) and the cold plate (1); The cooling liquid flows into the immersion chamber (15) from the liquid inlet connector (7), flows through the high power consumption device, and then flows out from the liquid outlet connector (8); The overflow valve (9) is located at the end of the coolant flow channel and is used for overpressure relief.

2. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The layout of components on the printed circuit board (6) is as follows: high-power consumption components are concentrated in the area corresponding to the liquid inlet hole (11), low-power consumption components are arranged in the area corresponding to the liquid outlet hole (12), and no components are placed in the area covered by the pressure plate (3).

3. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The pressing plate (3) is a carbon fiber plate with a thickness of 2 mm. The contact surface between the pressing plate (3) and the printed circuit board (6) is roughened by grinding with 400-mesh sandpaper, and bonded with 3MDP420 epoxy resin glue and thermally cured at 80-120° C. for 24 hours.

4. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: It also includes reinforced heat dissipation fins (4) bonded to the surface of the high-power consumption device, wherein the direction of the fins is consistent with the flow direction of the cooling liquid.

5. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The base material of the cold plate (1) is 6063-T5 aluminum alloy, which is milled to form an immersion cavity (15) and a baffle, and the surface is anodized black. The size of the cold plate (1) is 233.2 mm long and 141.4 mm wide, and the thickness is adapted to the 4HP marine reinforcement module standard.

6. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The baffle is located between the liquid inlet (11) and the liquid outlet (12), 15 mm away from the edge of the immersion chamber, and is used to force the coolant to flow through all high-power consumption components.

7. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The overflow valve (9) is manually adjusted to a pressure resistance of 1 bar, and automatically releases the coolant when the internal pressure of the immersion chamber is greater than 1 bar; the coolant is 3M Novec fluorinated liquid, which has insulating properties and compatibility with adhesives / sealing materials.

8. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The sealing strip (2) is a D-shaped cross-section sealing component installed in an annular sealing groove (14) with a width of 2.6 mm and a depth of 1.8 mm.

9. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The electrical connector (10) is compatible with CPCI, CPCI-E or VPX standards, and the surface of the printed circuit board assembly is coated with a TS96-11 fluoropolyurethane triple-proof coating.

10. The reinforced semi-immersed liquid cooling heat dissipation board according to claim 1, characterized in that: The screw holes (16) are distributed along the periphery of the cold plate, with a spacing of ≤35 mm.

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