Self-adaptive negative pressure cavity structure and method for chip heat dissipation

Abstract

The invention provides a self-adaptive negative pressure cavity structure and method for chip heat dissipation, and relates to the field of electronic hardware, the self-adaptive negative pressure cavity structure comprises a circuit board, and the lower surface of the circuit board is electrically connected with a chip; the heat dissipation substrate is arranged below the chip, and the heat dissipation substrate is fixedly connected with the circuit board; a heat dissipation conductor is arranged between the heat dissipation substrate and the chip, the heat dissipation conductor is in surface contact with the chip, and the heat dissipation substrate and the heat dissipation conductor are correspondingly provided with a first cavity and a second cavity respectively; the first cavity and the second cavity are in a negative pressure environment and are used for containing a cooling medium, the first cavity and the second cavity are communicated to form a circulating flow channel allowing the cooling medium to flow between the first cavity and the second cavity, and capillary structures are arranged in the first cavity, the second cavity and the circulating flow channel; the chip is efficiently cooled between the first cavity and the second cavity through flowing and phase change of the cooling medium, the heat dissipation mode is optimized under the condition that the size of the heat dissipation structure of the chip is not changed, and the heat dissipation effect is improved.

Description

Technical Field

[0001] This invention relates to the field of electronic hardware, and in particular to the field of heat dissipation for chips. Background Technology

[0002] With the continuous development of semiconductor technology, circuit boards in high-density, high-power electronic devices integrate multiple high-power chips. These chips generate a lot of heat when they are working, and heat sinks must be used to dissipate the heat in time to avoid damage caused by overheating.

[0003] Currently, chip heat dissipation mainly relies on thermally conductive materials to transfer heat to a heat sink, which then dissipates the heat through conduction. To improve heat dissipation, heat sinks are typically designed to be relatively large. However, this approach of increasing heat sink size has, to some extent, limited the miniaturization of chips. Furthermore, their heat dissipation capacity also has an upper limit; for high-power chips, insufficient heat dissipation can easily prevent them from operating at full capacity. Summary of the Invention

[0004] This invention provides an adaptive negative pressure cavity structure and method for chip heat dissipation, which aims to solve the problem of low heat dissipation efficiency of high-power chips, thus limiting chip power.

[0005] To achieve the above objectives, in a first aspect, embodiments of the present invention provide an adaptive negative pressure cavity structure for chip heat dissipation, comprising: A circuit board, on the lower surface of which a chip is electrically connected; A heat dissipation substrate is disposed below the chip, and the heat dissipation substrate is fixedly connected to the circuit board; A heat dissipation conductor is disposed between the heat dissipation substrate and the chip, and the heat dissipation conductor is in contact with the chip surface. The heat dissipation substrate and the heat dissipation conductor are respectively provided with a first cavity and a second cavity. The first cavity and the second cavity are negative pressure environments and are used to contain cooling medium. The first cavity and the second cavity are connected to form a circulation channel for the cooling medium to flow between the first cavity and the second cavity. The inner walls of the first cavity, the second cavity and the circulation channel all have capillary structures.

[0006] Preferably, the circulation channel includes a central tube disposed on the lower surface of the heat dissipation conductor and communicating with the second cavity, the lower end of the central tube being floatingly inserted into the heat dissipation substrate and communicating with the first cavity; The circulation channel also includes a guide tube, the upper end of which is fixedly connected to the heat dissipation conductor and communicates with the second cavity, and the lower end of which is floatingly connected to the heat dissipation substrate and communicates with the first cavity. The heat dissipation conductor is in contact with the chip through a thermally conductive layer.

[0007] Preferably, the lower end of the first cavity is open, and a cover that can be detachably connected to the heat dissipation substrate is provided below the first cavity, the cover being used to close the lower end of the first cavity; The top end of the guide tube is provided with a thread for connecting with the heat dissipation conductor, and the bottom end of the guide tube is provided with a limiting ring. The heat dissipation substrate has a plurality of through holes formed above the first cavity. The guide tubes, with the same number of through holes as the number of through holes, are inserted into the through holes one by one. The limiting ring abuts against the top wall of the first cavity. The lower end of the guide tube is also fitted with an elastic element, which provides pre-tightening force for the guide tube to float in the vertical direction.

[0008] Preferably, there is a dynamic seal between the central tube and the heat dissipation substrate, and between the guide tube and the heat dissipation substrate.

[0009] Preferably, the cover is provided with a one-way valve for evacuating the first chamber and the second chamber.

[0010] Preferably, the circuit board and the heat dissipation substrate are provided with support studs for forming a fixed connection, the upper end of the support studs being screwed to a non-circuit area of ​​the circuit board, and the lower end being screwed to the heat dissipation substrate.

[0011] Preferably, the cooling medium is a liquid that undergoes a phase transition from liquid to gas at a preset temperature, and the preset temperature is lower than the chip's heating temperature.

[0012] Preferably, the cooling medium is deionized water.

[0013] Secondly, this application also provides a heat dissipation method, which adopts the aforementioned adaptive negative pressure cavity structure for chip heat dissipation. When the chip heats up, the cooling medium adsorbed by the capillary structure in the second cavity evaporates. The evaporated cooling medium flows to the first cavity through the circulation channel and condenses upon encountering cold. The condensed cooling medium is then circulated back to the second cavity through the capillary structure in the circulation channel to complete the heat dissipation.

[0014] Thirdly, this application also provides a heat dissipation method, which adopts the aforementioned adaptive negative pressure cavity structure for chip heat dissipation. When the chip heats up, the cooling medium adsorbed by the capillary structure in the second cavity evaporates. The evaporated cooling medium flows to the first cavity through the circulation channel and condenses upon encountering cold. The condensed cooling medium is then circulated back to the second cavity through the capillary structure in the circulation channel to complete the heat dissipation. When the chip generates heat, the volume of the heat-conducting layer expands, pushing the heat dissipation conductor and the guide tube downward.

[0015] The above-described solution of the present invention has the following beneficial effects: First, this application creates a first cavity on a heat dissipation substrate and sets a heat dissipation conductor with a second cavity in contact with the chip surface. The flow and phase change of the cooling medium between the first and second cavities are used to efficiently dissipate heat from the chip. This optimizes the heat dissipation method without changing the volume of the chip's heat dissipation structure, significantly improving the heat dissipation effect. This heat dissipation method not only retains the original heat conduction heat dissipation method of the heat dissipation substrate, but also conducts heat out of the chip in a timely manner through continuous phase change and circulation of the cooling medium, avoiding heat accumulation on the chip.

[0016] Secondly, this application also makes the central tube and guide tube that form the circulation channel floatingly connected to the heat dissipation substrate, which helps to alleviate the problem of circuit board warping caused by thermal stress or assembly stress when the volume of the heat-conducting layer expands.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of this application; Figure 2 yes Figure 1 Enlarged view of part A Figure 3 This is an exploded view of this application; Figure 4 This is a cross-sectional view of the heat dissipation conductor; Figure 5 This is a cross-sectional view of the guide tube.

[0019] [Explanation of Labels in the Attached Image] 10-Circuit board, 11-Support stud, 20-Chip, 21-Heat-conducting layer, 30-Heat-dissipating substrate, 31-First cavity, 32-Cap, 33-One-way valve, 40-Heat-dissipating conductor, 41-Second cavity, 50-Circulation channel, 51-Central tube, 52-Guide tube, 53-Limiting ring, 54-Elastic element, 55-Sealing ring. Detailed Implementation

[0020] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0021] like Figures 1-5As shown, this application provides an adaptive negative pressure cavity structure for chip heat dissipation, including a circuit board 10, a heat dissipation substrate 30, and a heat dissipation conductor 40. The circuit board 10 has a circuit area and a non-circuit area. A chip 20 is disposed on the circuit area and electrically connected to the circuit area, enabling the chip 20 to operate. The heat dissipation substrate 30 is disposed below the circuit board 10, and the circuit board 10 and the heat dissipation substrate 30 are fixedly connected, forming a space between the circuit board 10 and the heat dissipation substrate 30 for mounting the heat dissipation conductor 40. The heat dissipation conductor 40 is in surface contact with the chip 20. The heat dissipation substrate 30 has a first cavity 31, and the heat dissipation conductor 40 has a second cavity 41. The first cavity 31 and the second cavity 41 form a negative pressure space, and a cooling medium is contained in the first cavity 31 and the second cavity 41. In this application, the first cavity 31 contains a cooling medium, and a circulation channel 50 is formed between the first cavity 31 and the second cavity 41 for the cooling medium to flow between the first cavity 31 and the second cavity 41. The inner walls of the first cavity 31, the second cavity 41, and the circulation channel 50 are all provided with capillary structures. Preferably, the capillary structure is a metal capillary structure.

[0022] In this application, by providing a circulation channel 50 between the heat dissipation conductor 40 and the heat dissipation substrate 30, the cooling medium in the first cavity 31 moves to the second cavity 41 through the capillary action of the capillary structure. The heat generated by the chip 20 during operation vaporizes the cooling medium in the second cavity 41 through the heat dissipation conductor 40. The vaporized cooling medium carries the heat to the first cavity 31 of the heat dissipation substrate 30 through the circulation channel 50. Since the temperature of the heat dissipation substrate 30 is lower than that of the chip 20, the vaporized cooling medium condenses back into liquid upon cooling and is replenished to the second cavity 41 by the capillary structure in the first cavity 31 and the circulation channel 50 through capillary action. The heat of the chip 20 is transferred to the heat dissipation substrate 30 for heat dissipation through the phase change of the cooling medium in the two cavities.

[0023] In this application, not only is the heat dissipation effect of the heat dissipation substrate 30 retained, but the heat dissipation rate of the chip 20 is also accelerated by the flow of the cooling medium, so as to avoid limiting the power of the chip 20 due to the accumulation of a large amount of heat at the chip 20.

[0024] Furthermore, the heat dissipation structure provided in this application does not require simply increasing the volume of the heat dissipation substrate 30 to ensure heat dissipation effect, which is conducive to the development of miniaturized chip 20.

[0025] On the other hand, when conventional chips 20 are connected to heat dissipation conductors 40, the inherent tolerances in the package heights of different chips 20 on circuit board 10 cause the circuit board 10 to bend and deform during assembly to fit the heat dissipation conductors 40, resulting in internal stress during assembly. As chips 20 heat up, the thermally conductive layer 21 expands in volume, increasing internal stress and making the circuit board 10 prone to warping. Prolonged exposure to this condition can easily lead to solder joint fatigue cracking, microcracks in the silicon wafer inside the chip 20, and decreased signal integrity, threatening the reliability of the device. Therefore, this application further improves the heat dissipation substrate 30 and heat dissipation conductors 40 to eliminate internal stress, thereby improving the service life of chips 20 and circuit board 10.

[0026] Specifically, the heat dissipation conductor 40 and the chip 20 are in surface contact through an adhesive thermal conductive layer 21 to transfer the heat generated by the chip 20 to the heat dissipation conductor 40 with maximum efficiency.

[0027] The aforementioned circulation channel 50 includes a central tube 51 with capillary structures on its inner wall and a guide tube 52 with capillary structures on its inner wall. The capillary structures on the inner walls of the central tube 51 and the guide tube 52 form channels at the center of their respective tubes. The central tube 51 is disposed on the lower surface of the heat dissipation conductor 40 and communicates with the second cavity 41. In this application, the central tube 51 can be integrally formed with the heat dissipation conductor 40, or they can be manufactured separately and then connected using existing technology. The lower end of the central tube 51 is floatingly inserted into the heat dissipation substrate 30 and communicates with the first cavity 31. During the floating insertion process, the central tube 51 can move vertically relative to the heat dissipation substrate 30, ensuring airtightness between the central tube 51 and the heat dissipation substrate 30.

[0028] Preferably, the inner wall of the central tube 51 may not have a capillary structure.

[0029] The capillary structure is made by sintering. Specifically, spherical or non-spherical metal powder is filled into the central tube 51 or the guide tube 52 and sintered at high temperature under a protective atmosphere to form a porous sintered body. The capillary structure made by this method has high porosity and strong liquid adsorption force, which is conducive to the rapid adsorption of cooling medium to the heat dissipation conductor 40.

[0030] The upper end of the aforementioned guide tube 52 is fixedly connected to the heat dissipation conductor 40 and communicates with the second cavity 41. The lower end of the guide tube 52 is floatingly connected to the heat dissipation substrate 30 and communicates with the first cavity 31. Similarly, the guide tube 52 can move vertically relative to the heat dissipation substrate 30, ensuring the airtightness between the guide tube 52 and the heat dissipation substrate 30.

[0031] In this embodiment, the upper end of the guide tube 52 is threadedly connected to the heat dissipation conductor 40.

[0032] During assembly, since both the central tube 51 and the guide tube 52 can float relative to the heat dissipation substrate 30, while ensuring effective contact between the chip 20 and the heat dissipation conductor 40, the internal stress of the circuit board 10 is also fully released, avoiding the internal stress generated during assembly.

[0033] When the chip 20 heats up, the heat-conducting layer 21 expands in volume, and the heat dissipation conductor 40 moves downward under force, relieving the internal stress of the circuit board 10. This avoids problems such as warping, solder joint cracking, and micro-cracks inside the chip 20 caused by long-term internal stress in the circuit board 10, thus improving the lifespan of the chip 20.

[0034] Specifically, the heat dissipation substrate 30 has a first cavity 31 cut upwards on its lower surface. The lower end of the first cavity 31 is open. A cover 32 is also provided on the lower surface of the heat dissipation substrate 30 at the first cavity 31, which can seal the first cavity 31. The top end of the guide tube 52 is provided with a threaded connection to the heat dissipation conductor 40, and the bottom end is provided with a limiting ring 53. The heat dissipation substrate 30 has a number of through holes above the first cavity 31, the number of which is the same as the number of guide tubes 52. During assembly, the guide tubes 52 are inserted into the corresponding through holes one by one, and the limiting rings 53 abut against the upper wall of the first cavity 31 to prevent the guide tubes 52 from coming out above the heat dissipation substrate 30.

[0035] An elastic element 54 is fitted at the lower end of the guide tube 52, and the elastic element 54 provides pre-tightening force for the vertical floating of the guide tube 52. Specifically, an elastic element 54 is fitted at the lower end of the guide tube 52, one end of the elastic element 54 abuts against the limiting ring 53, and the other end abuts against the cap 32, and the elastic element 54 is in a compressed state.

[0036] Preferably, the elastic element 54 is a spring.

[0037] The heat dissipation substrate 30 is also provided with a central hole above the first cavity 31 for the central tube 51 to float and be inserted, and the position of the central hole corresponds to the position of the central tube 51.

[0038] Preferably, both the guide tube 52 and the central tube 51 are made of copper to improve heat dissipation efficiency.

[0039] To ensure the airtightness of the first cavity 31, dynamic seals are formed between the central tube 51 and the heat dissipation substrate 30, and between the guide tube 52 and the heat dissipation substrate 30. In this embodiment, the dynamic seal is achieved using a sealing ring 55. The sealing ring 55, located on the guide tube 52, is positioned above the limiting ring 53.

[0040] Preferably, a one-way valve 33 is provided on the cover 32. After the cover 32 is fixed to the heat dissipation substrate 30, the gas in the first cavity 31 and the second cavity 41 is extracted by inverting the heat dissipation structure and through the one-way valve 33.

[0041] In this application, the cooling medium is a liquid that can transform from a liquid phase to a gas phase at a preset temperature, wherein the preset temperature is lower than the temperature at which the chip 20 generates heat. The cooling medium is added to the first cavity 31 before vacuuming.

[0042] In this embodiment, the cooling medium is deionized water. Deionized water boils at a temperature below 40 degrees Celsius in a vacuum environment, while the temperature of the chip 20 when it heats up is higher than this temperature. This ensures that the deionized water transforms from a liquid phase to a gas phase when the chip 20 heats up, absorbing the heat from the chip 20. Furthermore, deionized water is an insulating liquid, which can prevent corrosion of the capillary structure, central tube, and guide tube 52.

[0043] The aforementioned circuit board 10 and heat sink 30 are fixedly connected. Specifically, a stud is provided between the circuit board 10 and the heat sink 30. The upper end of the stud is screwed to the non-circuit area of ​​the circuit board 10, and the lower end is connected to the heat sink 30.

[0044] This application also provides a heat dissipation method based on the aforementioned adaptive negative pressure cavity structure for chip heat dissipation. When the chip 20 heats up, the cooling medium adsorbed by the capillary structure in the second cavity 41 absorbs heat and evaporates into a gas phase. At this time, the pressure in the second cavity increases, while the first cavity 31, being far from the chip 20, is at a lower temperature and pressure. Under the pressure difference between the first cavity 31 and the second cavity 41, the high-pressure gas phase cooling medium flows to the low-pressure end, that is, from the second cavity 41 to the first cavity 31 through the circulation channel 50. At this time, the temperature of the heat dissipation substrate 30 is still lower than the temperature of the chip 20, causing the evaporated cooling medium to condense upon contact with the cold air. The condensed cooling medium is then circulated back to the second cavity 41 through the capillary structure in the circulation channel 50 to complete vaporization. Through the continuous vaporization and condensation of the cooling medium, the heat generated by the chip 20 is transferred to the heat dissipation substrate 30, and the heat dissipation substrate 30 conducts heat with the outside environment, thereby cooling the chip 20.

[0045] During the heating of chip 20, the volume of heat-conducting layer 21 expands, and heat dissipation conductor 40 descends adaptively, causing the central tube 51 and guide tube 52 on heat dissipation conductor 40 to descend, thereby reducing the internal stress of chip 20 and circuit board 10.

Claims

1. An adaptive negative pressure cavity structure for chip heat dissipation, characterized in that, include: Circuit board (10), on the lower surface of the circuit board (10) a chip (20) is electrically connected. A heat dissipation substrate (30) is disposed below the chip (20), and the heat dissipation substrate (30) is fixedly connected to the circuit board (10); A heat dissipation conductor (40) is provided between the heat dissipation substrate (30) and the chip (20). The heat dissipation conductor (40) is in surface contact with the chip (20). The heat dissipation substrate (30) and the heat dissipation conductor (40) are respectively provided with a first cavity (31) and a second cavity (41). The first cavity (31) and the second cavity (41) are negative pressure environments and are used to contain cooling media. The first cavity (31) and the second cavity (41) are connected to form a circulation channel (50) for the cooling media to flow between the first cavity (31) and the second cavity (41). The inner walls of the first cavity (31), the second cavity (41) and the circulation channel (50) all have capillary structures.

2. The adaptive negative pressure cavity structure for chip heat dissipation according to claim 1, characterized in that: The circulation channel (50) includes a central tube (51) disposed on the lower surface of the heat dissipation conductor (40) and communicating with the second cavity (41). The lower end of the central tube (51) is floatingly inserted on the heat dissipation substrate (30) and communicating with the first cavity (31). The circulation channel (50) also includes a guide tube (52), the upper end of which is fixedly connected to the heat dissipation conductor (40) and communicates with the second cavity (41), and the lower end of which is floatingly connected to the heat dissipation substrate (30) and communicates with the first cavity (31). The heat dissipation conductor (40) and the chip (20) are in surface contact through the heat-conducting layer (21).

3. The adaptive negative pressure cavity structure for chip heat dissipation according to claim 2, characterized in that: The lower end of the first cavity (31) is open, and a cover (32) that can be detachably connected to the heat dissipation substrate (30) is provided below the first cavity (31). The cover (32) is used to close the lower end of the first cavity (31). The top end of the guide tube (52) is provided with a thread for connecting with the heat dissipation conductor (40), and the bottom end of the guide tube (52) is provided with a limiting ring (53). The heat dissipation substrate (30) has a plurality of through holes formed above the first cavity (31). The guide tube (52) with the same number of through holes is inserted into the through holes one by one. The limiting ring (53) abuts against the top wall of the first cavity (31). The lower end of the guide tube (52) is also fitted with an elastic element (54), which provides pre-tightening force for the guide tube (52) to float in the vertical direction.

4. The adaptive negative pressure cavity structure for chip heat dissipation according to claim 2, characterized in that: Dynamic seals are formed between the central tube (51) and the heat dissipation substrate (30), and between the guide tube (52) and the heat dissipation substrate (30).

5. The adaptive negative pressure cavity structure for chip heat dissipation according to claim 3, characterized in that: The cover (32) is provided with a one-way valve (33) for evacuating the first chamber and the second chamber.

6. The adaptive negative pressure cavity structure for chip heat dissipation according to claim 1, characterized in that: The circuit board (10) and the heat dissipation substrate (30) are provided with support studs (11) for forming a fixed connection. The upper end of the support studs (11) is screwed to the non-circuit area of ​​the circuit board (10), and the lower end is screwed to the heat dissipation substrate (30).

7. The adaptive negative pressure cavity structure for chip heat dissipation according to claim 1, characterized in that: The cooling medium is a liquid that undergoes a phase transition from liquid to gas at a preset temperature, which is lower than the heating temperature of the chip (20).

8. The adaptive negative pressure cavity structure for chip heat dissipation according to claim 7, characterized in that: The cooling medium is deionized water.

9. A heat dissipation method, employing the adaptive negative pressure cavity structure for chip heat dissipation as described in any one of claims 1-8, characterized in that: When the chip (20) heats up, the cooling medium adsorbed by the capillary structure in the second cavity (41) evaporates. The evaporated cooling medium flows through the circulation channel (50) to the first cavity (31) and condenses upon encountering cold. The condensed cooling medium is then circulated back to the second cavity (41) through the capillary structure in the circulation channel (50) to complete heat dissipation.

10. A heat dissipation method, employing the adaptive negative pressure cavity structure for chip heat dissipation as described in any one of claims 2-5, characterized in that: When the chip (20) heats up, the cooling medium adsorbed by the capillary structure in the second cavity (41) evaporates. The evaporated cooling medium flows through the circulation channel (50) to the first cavity (31) and condenses upon encountering cold. The condensed cooling medium is then circulated back to the second cavity (41) through the capillary structure in the circulation channel (50) to complete the heat dissipation. When the chip (20) heats up, the heat-conducting layer (21) expands in volume, pushing the heat dissipation conductor (40) and the guide tube (52) downward.

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