Modular functional unit for connecting high-performance electronic components

Abstract

The invention relates to a modular functional unit (1) for connecting high-performance electronic components (2) in a cooling system (3) with a 2-phase cooling fluid (4), the functional unit (1) being a current-conducting functional element (11), and the functional element (11) having a metallic surface (111) which is in contact with cooling fluid (4) at least partially or on all sides.

Description

[0001] Description

[0002] Modular functional unit for connecting electronic

[0003] high-performance components

[0004] The invention relates to a modular functional unit for connecting high-performance electronic components in a cooling system with a 2-phase cooling fluid.

[0005] Depending on the application, conventional electronic components are designed for a specific temperature range during operation and have an upper temperature limit that must not be exceeded. These components must therefore be cooled if necessary to ensure that their internal temperature remains below the specified upper limits. Cooling can be achieved, among other things, by the evaporation of a dielectric heat transfer fluid, such as perfluorocarbons, fluorocarbons, fluoroketones, or fluorocarbon ethers. Depending on its composition, the dielectric heat transfer fluid can have a boiling point at atmospheric pressure in the range of approximately 35°C to approximately 100°C. Within this temperature range, the boiling point of the heat transfer fluid at atmospheric pressure is lower than the permissible upper limits for which conventional electronic components are designed.The electronic components are immersed in the liquid phase of the heat transfer fluid. When the surfaces of the electronic components in contact with the dielectric heat transfer fluid reach the boiling point of the heat transfer fluid, the nearby liquid fluid evaporates, thus absorbing the excess heat from the electronic components. Liquid immersion cooling systems, such as two-phase immersion cooling systems, are an active cooling solution for electronic components that generate a lot of heat during operation. When the components are immersed in a two-phase heat transfer fluid, which usually has a low boiling point, the heat generated by the electronic component can evaporate the surrounding liquid heat transfer fluid, thereby dissipating heat from the electronic component.A condenser device liquefies the gaseous heat transfer fluid, which is then returned to the reservoir for cooling.

[0006] A two-phase immersion cooling system with a cooling basin is known from US Pat. No. 10,512,192 B2. A condensation chamber, in which the gaseous fluid produced during the cooling process is condensed, communicates with the liquid fluid in the cooling basin. A vapor diversion structure is arranged above the heat-generating electronic components located within the cooling medium in the cooling basin. The vaporized fluid is directed into the condensation chamber for condensation by means of the vapor diversion structure. The condensation chamber is located entirely within the cooling basin. Only the supply and discharge lines for the fluid contained in the cooling tubes pass through the cooling basin wall.

[0007] In this context, a cooling system for computer components is known from US Pat. No. 1,0477,726 B1. A pressure-controlled container contains a heat-conducting, dielectric heat transfer fluid in liquid and gaseous phases, which has a boiling point below 80°C at atmospheric pressure. Computer components are arranged in the container and are at least partially immersed in the liquid phase of the heat transfer fluid. A condenser condenses the dielectric gas-phase fluid evaporated by the heat generated by the computer components into a dielectric liquid-phase fluid. The internal pressure in the pressure-controlled container is reduced to as low as 650 hPa. By controlling the pressure in the container at which the system operates, the user can influence the temperature at which the dielectric fluid evaporates. This allows for increased cooling performance.The operation of a computer system within a pressure-controlled vessel at an operating pressure that deviates from the ambient pressure usually requires a structural adaptation of the system as a whole.

[0008] The power supply is designed to provide various electrical inputs that interact to form a power distribution system. An example described is a 415V input to a main breaker, which is then distributed to a series of power modules that convert the 415V AC input into a 12V DC output.

[0009] A mounting system on which computer components are mounted is designed to serve as a link between the electrical components and the control and communication systems. Computer components are attached directly or indirectly to the mount and held in a stationary position. The design of the mounting system and the electrical power supply must be adapted based on the specific requirements of the respective application.

[0010] To further increase cooling performance, US Pat. No. 8,619,425 B2 discloses a cooling device with a housing that at least partially surrounds electronic components and forms a fluid-tight chamber around them. The cooling device comprises a boiling fluid mixture comprising a first dielectric fluid and a second dielectric fluid located in the fluid-tight chamber, with the electronic components completely immersed in the boiling fluid mixture. Furthermore, the cooling device comprises a condensation fluid located in the fluid-tight chamber, the condensation fluid and the boiling fluid mixture being immiscible, and the condensation fluid having a lower specific gravity than the boiling fluid mixture and a higher thermal conductivity than the boiling fluid mixture.The condensation fluid facilitates the condensation of the vaporized boiling liquid mixture within the liquid-tight chamber. Furthermore, the cooling device comprises a cooling structure within the fluid-tight chamber, wherein the cooling structure has a condensation zone and a subcooling zone. The condensation zone is in contact with the condensation fluid, and the subcooling zone is in contact with the boiling liquid mixture.

[0011] Such measures are intended to more efficiently cool electronic components, such as circuit boards, using multiphase fluids in an immersion cooling arrangement. However, the cooling performance of such cooling devices is limited, especially for high-performance electronics, because these components generate enormous amounts of heat locally during operation, which can only be dissipated to a limited extent by conventional cooling devices.

[0012] In addition to the cooling of electronic components in immersion cooling systems, cooling plates are also known for cooling semiconductor components in power electronics, to which the components to be cooled are directly mounted. A cooling plate usually has an inlet and an outlet for the coolant flow. The liquid coolant absorbs the heat generated by the electronic component and transfers the absorbed heat to the coolant. The cooling plates usually cool with a comparatively low flow of liquid coolant and offer a certain degree of temperature constancy within the cooling performance of liquid coolants. In this context, a further development of cooling plate technology is known from the document EP 2 484 190 B1, in which an improved cooling plate with pins is proposed. The cooling plate consists of a housing with an inlet, an outlet, a base, and a cover.The base consists of a base plate with an insert. A plurality of pins extend from the insert into the housing, allowing fluid to flow around the pins. The pins can have a spiral shape, with the cross-sectional profile of the pins varying along the length of the pin.

[0013] Special precautions are also known regarding thermal contact between the components to be cooled and the cooling plate.

[0014] EP 2 752 104 B1 discloses a base plate as a component of a cooling plate for cooling electronics, which base plate consists of at least a first metal and a second metal, which are plated together by a metallurgical bond. The base plate has an improved surface with ribs, pins, or other structures made entirely of the second metal.

[0015] The invention is based on the object of improving the thermal management of the heat generated during the operation of high-performance electronic components.

[0016] The invention is defined by the features of claim 1. The further dependent claims relate to advantageous embodiments and developments of the invention.

[0017] The invention includes a modular functional unit for connecting high-performance electronic components in a cooling system with a 2-phase cooling fluid, wherein the functional unit is designed as a flow-conducting functional element, and the functional element has a metallic surface which is at least partially or all-sidedly in contact with cooling fluid.

[0018] The invention is based on the idea that the modular functional unit is designed as a current-conducting functional element for connecting high-performance electronic components. The modular functional unit includes, for example, conductor tracks for controlling and interconnecting IGBTs or MOSFETs and their functional low-inductance integration at the chip level with short conduction paths.

[0019] Although high-performance components generally boast high levels of efficiency, cooling is essential. For this purpose, the modular functional unit features a metallic surface that comes into direct contact with a two-phase cooling fluid of a cooling system. Direct contact with the metallic surface is at least partial, but extends over as large a surface as possible on all sides of the connecting lines. This ensures good thermal contact between the metallic surface and the fluid, immediate, direct, and three-dimensional. Consequently, the heat generated in the high-performance components is dissipated to the cooling system fluid via the conductive functional element, close to the heat source.

[0020] In other words, a conductive functional element, through its dual function of conducting current and dissipating heat, offers multiple benefits and efficiently dissipates the heat generated in high-performance components. Furthermore, the modular functional unit can also make a significant contribution to the mechanical stability of a circuit arrangement as a support unit.

[0021] Heat absorption via the cooling system occurs through the two-phase cooling fluid, whereby at least the metallic surface of the flow-conducting functional element of the high-performance components comes into contact with the liquid phase of the cooling fluid, causing the cooling fluid to evaporate and the resulting gas phase to escape against gravity. The gaseous fluid can also be guided away from the respective heat source via appropriate conducting structures and recondensed elsewhere.

[0022] The current-conducting functional elements can be metallic three-dimensional support units, on whose highly thermally conductive surfaces the high-performance components are arranged. For example, profiles or pipes can also serve as support units.

[0023] In a preferred embodiment of the invention, the metallic surface can be designed as a structured evaporator surface. The metallic surface can have ribbing, pins, or microchannels as a surface-enlarging structure. The structure can be formed using rolling or cutting tools, lasers, or chemical-physical processes, such as etching processes or coatings. This enlargement of the metallic surface results in improved heat exchange with the fluid.

[0024] Advantageously, the metallic surface can support nucleation as a structured evaporator surface. Structures such as cavities or other depressions that support bubble nucleation and the evaporation process of the liquid fluid are considered.

[0025] In a preferred embodiment of the invention, the cooling fluid can be hermetically sealed. In the context of the invention, hermetically sealed means a fluid-filled volume from which no fluid exchange with the environment can occur. The hermetic seal also prevents air, water vapor, or any other gas from entering the system with the cooled electronic components. In an advantageous embodiment of the invention, the cooling fluid can be enclosed in a housing. A housing is one way of hermetically sealing the fluid phases from the environment. Solid housing shapes, such as plastic housings, can be used for this purpose. These have a defined volume and are designed to be pressure-stable. In a housing, several high-performance components can be combined into a functional unit, also using flow-conducting functional elements.

[0026] In an advantageous embodiment of the invention, the housing can be designed with a variable volume. By means of a variable housing volume, the excess pressure in the system that arises during the evaporation process of the fluid can be reduced or advantageously adjusted. For variable and pressure-dependent housing volumes, elastic housing materials can be used. Structural solutions, such as a bellows with variable volume, can also be suitable for pressure management.

[0027] In a preferred embodiment of the invention, the housing can have a pressure control valve. This can counteract a supercritical pressure level of the vaporous fluid caused by strong heat input during the evaporation process. However, such valve systems result in a certain amount of fluid being lost to the environment when there is excess pressure in the cooling system. In this case, it may be necessary to replenish the escaping fluid.

[0028] In a preferred embodiment, the housing can have at least one passage for an electrical connection cable. The passage for the electrical connection cable is, for example, the external connection of the modular functional unit to the control units. At the passage, connection flanges can provide suitable feedthroughs for electrical cables that supply the cooling system with electrical energy. The feedthroughs can be polygonal, square, or round holes in the housing wall. Within the scope of the advantageous embodiment of the invention, elastic connection flanges can also be fully elastic feedthroughs or consist of a combination of rigid and elastic sections.

[0029] Elastic connection flanges can cover the recess in the housing wall in a fluid-tight manner from the outside or inside. This allows for the consideration and adaptation of tensile and compressive loads on the elastic connection flange. Furthermore, multiple connection flanges for multiple feedthroughs are being considered, arranged on at least one side of the housing wall.

[0030] Advantageously, the cooling fluid can have a boiling point range of 30°C to 90°C. If the heat input from high-performance components into the cooling system is low, the higher the boiling point of the cooling fluid, the more heat can be dissipated through the liquid portion of the fluid by convection. At high boiling points, the temperature peaks of the high-performance components can then be effectively reduced by evaporating as much of the liquid as possible.

[0031] In a particularly preferred embodiment, the functional element can consist, at least on the surface, of Au, Ag, Cu, Pt, Al, Fe, or alloys of these elements. For alloys, compositions with good thermal conductivity are preferably selected.

[0032] Advantageously, the flow-conducting functional element can be connected to the high-performance components by joining connections with reduced thermal resistance. In a particularly preferred embodiment, the joining connections can be made of thermally conductive material. A thermally conductive material is advantageous for improving the thermal connection of the high-performance components. It is important that it meets both the thermal and mechanical requirements of the application. Fastening by soldering or screwing to carrier plates can be used. Thermally conductive pastes, thermal pads, or thermally conductive adhesives are also preferred.

[0033] Embodiments of the invention are explained in more detail with reference to the schematic drawings.

[0034] Showing:

[0035] Fig. 1 shows a schematic cross-section of a high-performance component with a modular functional unit in a cooling system with a housing,

[0036] Fig. 2 shows a schematic oblique view of a printed circuit board with current-conducting functional elements of a modular functional unit and high-performance components,

[0037] Fig. 3 shows a schematic view of metallic three-dimensional carrier units of a modular functional unit as current-conducting functional elements with high-performance components,

[0038] Fig. 4 schematically shows a view of a cross section AA of the carrier unit from Figure 3.

[0039] Corresponding parts are provided with the same reference numerals in all figures.

[0040] Fig. 1 shows a schematic cross-section of a high-performance component 2 in the form of a diode with a modular functional unit 1 in a cooling system 3 with a housing 5. The current-conducting functional element 11 has a free metallic surface 111 which comes into direct contact with the cooling fluid 4. The liquid cooling fluid 41 evaporates on the metallic surface and effectively absorbs the heat generated in the high-performance component 2. The gaseous cooling fluid 42 rises and condenses on the inner wall of the housing 5. Likewise, a separate condenser (not shown in detail in Fig. 1) can be arranged inside the housing or connected externally via gas lines to liquefy the gaseous cooling fluid 42.

[0041] A pressure control valve 51 is arranged in the upper area of ​​the housing 5 for pressure regulation and to reduce pressure peaks. A passage 52, through which connecting lines 8 are routed through the wall of the housing 5, serves as the connection to the outside. Thus, the modular functional unit 1 is designed to serve a dual function, both as a flow-conducting functional element 11 for connecting high-performance electronic components 2 and as a dual function for effective heat dissipation.

[0042] Fig. 2 schematically shows an oblique view of a circuit board 7 with flow-conducting functional elements 11 of a modular functional unit 1 and high-performance components 2. The flow-conducting functional elements 11 have a metallic surface 111 that can come into direct contact with the cooling fluid. Joints 6 also improve heat conduction from the high-performance components 2 to the modular functional unit 1.

[0043] Fig. 3 shows a schematic view of metallic three-dimensional carrier units as current-conducting functional elements 11 of a modular functional unit 1 with high-performance components 2. Adjacent current-conducting functional elements 11 are electrically separated from one another by insulators 9. Suitable connecting lines 8 connect the respective high-performance component 2 to a current-conducting functional element 11. In this embodiment, the three-dimensional carrier unit is tubular along an axis of symmetry A.

[0044] Fig. 4 shows a schematic view of a cross section AA of the modular functional unit 1 of a tubular support unit from Figure 3. In this case, the high-performance components 2 are arranged three-dimensionally around the circumference of the tube.

[0045] List of reference symbols

[0046] 1 modular functional unit

[0047] II current conducting functional element

[0048] III metallic surface

[0049] 2 high-performance component

[0050] 3 Cooling system

[0051] 4 Cooling fluid

[0052] 41 liquid cooling fluid

[0053] 42 gaseous cooling fluid

[0054] 5 housings

[0055] 51 Pressure control valve

[0056] 52 Passage point for connecting cable

[0057] 6 Joining connection

[0058] 7 Circuit board

[0059] 8 connecting cable

[0060] 9 Insulator

[0061] A axis of symmetry

Claims

Patent claims 1 . Modular functional unit (1) for connecting high-performance electronic components (2) in a cooling system (3) with a 2-phase cooling fluid (4), characterized in that - that the functional unit (1 ) is designed as a current-conducting functional element (11 ), and - that the functional element (11) has a metallic surface (111) which is at least partially or all-round in contact with cooling fluid (4).

2. Modular functional unit (1) according to claim 1, characterized in that the metallic surface (111) is designed as a structured evaporator surface.

3. Modular functional unit (1) according to claim 2, characterized in that the metallic surface (111) as a structured evaporator surface supports nucleation.

4. Modular functional unit (1) according to one of claims 1 to 3, characterized in that the cooling fluid (4) is hermetically enclosed.

5. Modular functional unit (1) according to claim 4, characterized in that the cooling fluid (4) is enclosed by a housing (5).

6. Modular functional unit (1) according to claim 5, characterized in that that the housing (5) is designed to be variable in its volume.

7. Modular functional unit (1) according to claim 5 or 6, characterized in that the housing (5) has a pressure control valve (51).

8. Modular functional unit (1) according to one of claims 5 to 7, characterized in that the housing (5) has at least one passage point (52) for an electrical connection line (8).

9. Modular functional unit (1) according to one of claims 1 to 8, characterized in that the cooling fluid (4) has a boiling temperature range of 30°C to 90°C.

10. Modular functional unit (1) according to one of claims 1 to 9, characterized in that the functional element (11) consists at least on the surface of Au, Ag, Co, Pt, Al, Fe or alloys of these elements.

11. Modular functional unit (1) according to one of claims 1 to 10, characterized in that the functional element (11) is connected to the high-performance components (2) by joining connections (6) with reduced thermal resistance.

12. Modular functional unit (1) according to claim 11, characterized in that the joining connections (6) consist of heat-conducting material.

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