A heat dissipating composite material and a phase change cooling chip device based on thermomagnetic material

Abstract

The application relates to the field of high-heat-flow-density chip heat dissipation, in particular to a composite material for heat dissipation and a phase change cooling chip device based on a thermomagnetic material, wherein the composite material is composed of a thermosensitive magnetic material and a phase change material; the composite material generates flow through the action of magnetic force, dynamically contacts a target device which needs to be temperature-controlled, and intensively cools the target device, the composite material for heat dissipation and the phase change cooling chip device based on the thermomagnetic material have the advantages of simple structure, spontaneous circulation control and stable and reliable cooling effect, and can realize more simple and efficient cooling of high-integration-degree chips.

Description

Technical Field

[0001] This invention relates to the field of chip heat dissipation, especially to chip heat dissipation with high heat flux density, and specifically to a composite material for heat dissipation and a phase change cooling chip device based on thermomagnetic materials. Background Technology

[0002] In recent years, with the rapid development of micro-nano electronics technology, the integration density of chip transistors has increased rapidly. Currently, the number of transistors integrated per unit area is increasing year by year, while the chip size is gradually decreasing. This leads to a significant increase in the heat flux density of the chip, and the activity of transistors in different functional modules within the chip causes highly uneven heat generation, resulting in hot spots that vary with time and space within the chip. The heat flux density at these hot spots can reach as high as 500–1000 W / cm². 2 The emergence of hot spots generates localized high temperatures and thermal stress within the chip. Increased chip temperature and temperature gradients exponentially shorten the mean time between failures (MTBF) and the lifespan of electronic devices. Related research indicates that for every 10°C increase in chip temperature, MOS current drive capability decreases by approximately 4%, interconnect delay increases by approximately 5%, and the failure rate at 80°C is 7.5 to 32 times higher than at 40°C. Over 55% of electronic device failures are related to chip thermal management. Therefore, chip thermal management systems must not only handle background heat but also rapidly dissipate heat from hot spots, maintaining the overall chip temperature while reducing the temperature of hot spots. Currently, with the rapid increase in chip power and power density, chip energy consumption and heat dissipation problems are becoming increasingly prominent, leading to a more severe "thermal barrier" problem. The market demand for high-performance chip cooling technology has reached unprecedented levels. Therefore, developing new chip heat dissipation methods and devices is of great significance for solving chip heat dissipation problems.

[0003] To address the aforementioned issues, the most widely used chip cooling method currently is the fan + heatsink approach. While this method is relatively mature, its cooling capacity is still quite limited and cannot meet the rapidly growing demands for cooling high heat flux density chips. Other chip cooling technologies include liquid cooling, microchannel heat sinks, thermoelectric cooling, and thermoelectric ion cooling, but most of these technologies are still in the research and trial phase and are not yet fully mature. Furthermore, we have found that when solid-liquid phase change materials (SCTs) are used to cool chips, the liquid material cannot be removed promptly after the solid SCT liquefies, resulting in insufficient contact between the chip and the solid SCT and low heat dissipation efficiency. Therefore, researchers are exploring the addition of temperature-controlled materials, similar to deformable metals, to improve heat transfer efficiency. Existing chip cooling devices using external magnetic fields include, for example, patent CN114928982A, which discloses a microchannel cooling system coupled with a magnetic field-controlled phase change cooling system under microgravity conditions. This system includes a magnetic field generator, a housing, a microchannel network, and a magnetic phase change material. The housing is used to attach to the target electronic device under thermal control. The microchannel network has a honeycomb structure, and the magnetic phase change material fills the cavities formed by the honeycomb structure. The inlet and outlet of the microchannel network are connected to a magnetic nanofluid to form a magnetic nanofluid circulation cooling loop. The magnetic field generator controls the melting rate of the magnetic phase change material, thereby controlling its thermal conductivity. This, in turn, controls the flow rate of the magnetic nanofluid after the phase change material melts, thus controlling the rate at which the heat from the phase change material is carried away from the external environment. While this cooling system achieves adjustable heat dissipation efficiency and stability to some extent through structural optimization, it requires controlling a magnetic field generator to change the magnetic field to adjust the cooling rate, making operation complex and requiring manual intervention. Furthermore, patent CN115360156A discloses a chip heat dissipation method and device based on magnetohydrodynamics. This method utilizes the high thermal conductivity of liquid metal and significantly improves wall-to-wall convective heat transfer efficiency by optimizing the flow boundary layer structure, making it suitable for high-heat-flux-density electronic heat dissipation applications such as high-performance computers and laser pump sources. However, this magnetohydrodynamic chip heat dissipation method and device suffers from structural complexity and demanding material usage conditions. More importantly, the technologies disclosed in the aforementioned patents are all passive chip heat dissipation methods, unable to spontaneously regulate the cooling effect to maintain the chip at a stable normal operating temperature.

[0004] In summary, existing phase change cooling chip technologies not only lack a simple and reliable way to adjust the temperature of the cooling chip, but also lack a way to spontaneously enhance the heat transfer capability of material contact. They cannot meet the needs of rapid chip cooling under various conditions, thus limiting the application scenarios and cooling effect of phase change cooling chip methods. Summary of the Invention

[0005] This invention designs a heat dissipation composite material and a phase change cooling chip device based on thermomagnetic materials to overcome the technical problems of current phase change cooling chip technology, such as the chip not being able to fully contact the phase change material, the inability to spontaneously regulate the cooling effect, and the complex structure of the phase change cooling chip system, which is difficult to implement and control.

[0006] To address the aforementioned problems, this invention discloses a composite material for heat dissipation. The composite material is composed of a thermosensitive magnetic material and a phase change material. The composite material generates flow through the action of magnetic force, dynamically contacting the target device that requires temperature control and enhancing its heat dissipation and cooling.

[0007] Furthermore, the Curie point temperature of the thermistor magnetic material is 5 to 15°C lower than the highest temperature during normal operation of the target device that requires temperature control.

[0008] Furthermore, the Curie point temperature of the thermosensitive magnetic material is less than or equal to the phase transition temperature of the phase transition material.

[0009] Furthermore, the phase change material is a solid-liquid phase change material.

[0010] Furthermore, by adjusting the volume ratio of each raw material component, the magnetic force initially experienced by the composite material when starting the target device requiring temperature control is greater than twice the total weight of the composite material and less than or equal to five times the total weight of the composite material.

[0011] Furthermore, the preparation process of the composite material is as follows:

[0012] First, the solid phase change material is heated until it is completely melted into a liquid state. Then, the thermosensitive magnetic material powder is added to the liquid phase change material while stirring, and the mixture is stirred until it has a uniform color. Heating is stopped, and stirring is continued. When it cools down to the point where it begins to solidify, stirring is stopped, and finally it is allowed to cool naturally to obtain the composite material.

[0013] A phase change cooling chip device based on thermomagnetic materials, comprising:

[0014] The aforementioned composite materials;

[0015] A container used to hold the composite material;

[0016] A magnetic force generating unit is used to provide a constant magnetic field for the composite material;

[0017] The composite material is filled in the container, which is in contact with the target device that requires temperature control.

[0018] Furthermore, when the composite material flows due to the attraction of magnetic force, the composite material and the magnetic force generating unit are positioned opposite each other on both sides of the target device that requires temperature control.

[0019] Furthermore, the composite material generates flow through the attraction of magnetic force, the container is placed on the upper side of the target device that needs temperature control, the bottom surface of the container contacts the target device that needs temperature control, and the magnetic force generating unit is placed on the lower side of the target device that needs temperature control.

[0020] Furthermore, the container is made of a non-magnetic metallic thermally conductive material.

[0021] Furthermore, the phase change cooling chip device also includes:

[0022] A thermally conductive silicone grease layer is disposed between the container and the target device that requires temperature control, and is used to fill the gap between the container and the target device that requires temperature control.

[0023] Furthermore, the magnetic force generating unit is a sheet magnet with a thick magnetized surface.

[0024] The heat dissipation composite material and the phase change cooling chip device based on thermomagnetic materials described in this application have the following advantages:

[0025] First, this application utilizes the characteristic that the magnetism of thermistor magnetic materials decreases and eventually disappears as the temperature rises, and promotes dynamic and full contact between the phase change material and the heat-generating chip through magnetic force, thereby realizing a spontaneous enhanced phase change cooling chip process.

[0026] Second, the phase change cooling chip device based on thermomagnetic materials described in this application can independently achieve cyclic heat transfer through solid-liquid phase change flow, and has high thermal conductivity, excellent isothermal properties, and variable heat flux density.

[0027] Third, the phase change cooling chip device based on thermomagnetic materials described in this application avoids complex internal circuits and has the advantages of simple structural design and easy implementation.

[0028] In summary, the heat dissipation composite material and the phase change cooling chip device based on thermomagnetic material described in this application not only meet the need for recycling of non-open systems, but also enable the heat-generating chip to come into more full contact with the phase change material, while avoiding complex internal circuits. It has the advantages of simple structure, spontaneous circulation control and stable and reliable cooling effect, and can achieve simpler and more efficient cooling of highly integrated chips. Attached Figure Description

[0029] Figure 1 This is a three-dimensional structural schematic diagram of the phase change cooling chip device based on thermomagnetic materials according to the present invention;

[0030] Figure 2 This is a schematic diagram of the planar structure of the phase change cooling chip device based on thermomagnetic materials according to the present invention;

[0031] Figure 3 This is a schematic diagram illustrating the working principle of the phase change cooling chip device based on thermomagnetic materials described in this invention.

[0032] Figure 4 This is a graph showing the change in the ratio of magnetic force to gravity in the composite material described in Example 1 of the present invention as a function of the proportion of ferrite.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Container; 2. Composite material; 2'. Liquid composite material; 3. Thermally conductive silicone grease layer; 4. Heating chip; 5. Permanent magnet. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0036] like Figures 1-3 As shown, a phase change cooling chip device based on thermomagnetic materials includes:

[0037] Composite material 2 is composed of a thermosensitive magnetic material and a phase change material. The composite material 2 generates flow through the action of magnetic force and dynamically contacts the target device that needs to be temperature controlled, such as the heating chip 4, to enhance heat dissipation and cooling.

[0038] Container 1 is used to hold the composite material 2;

[0039] A magnetic force generating unit, such as a permanent magnet 5, is used to provide a constant magnetic field for the composite material 2;

[0040] The composite material 2 is filled in the container 1, and the container 1 is in contact with the heating chip 4.

[0041] As some embodiments of this application, the composite material 2 can generate flow through the attraction of magnetic force, dynamically contacting the target device that requires temperature control and enhancing its heat dissipation and cooling. It should be noted that the dynamic contact between the composite material 2 and the target device requires temperature control means that the composite material 2 continuously flows over the contact surface between the container 1 and the target device, thus dynamically enhancing heat dissipation and cooling compared to the traditional static contact method.

[0042] Specifically, when the composite material 2 flows due to the attraction of magnetic force, the composite material 2 and the magnetic force generating unit, such as the permanent magnet 5, can be placed opposite each other on both sides of the target device that needs to be temperature controlled, so that the permanent magnet 5 can attract the composite material 2 from a distance to move towards the target device that needs to be temperature controlled.

[0043] It should be noted that in this application, the heating chip 4 can be not only a semiconductor element product carrying an integrated circuit, but also other target electronic devices that require temperature control.

[0044] As some embodiments of this application, the container 1 and the permanent magnet 5 are arranged horizontally or vertically opposite each other on both sides of the heating chip 4, such as the front and back sides, the left and right sides, or the top and bottom sides, specifically so that the permanent magnet 5 can attract the composite material 2 to move towards the side closer to the heating chip 4.

[0045] Preferably, the container 1 is disposed on the upper side of the heating chip 4, the bottom surface of the container 1 contacts the heating chip 4, and the permanent magnet 5 is disposed on the lower side of the heating chip 4.

[0046] Furthermore, the container 1 is made of a high thermal conductivity material with good thermal conductivity and no magnetism.

[0047] Preferably, the container 1 can be made of a non-magnetic, high thermal conductivity metal material.

[0048] As some embodiments of this application, the container 1 may be made of pure copper or a non-magnetic alloy.

[0049] As some embodiments of this application, the container 1 can be a fully enclosed container or a semi-enclosed container, such as a container with an open top. Preferably, the container 1 is a fully enclosed container.

[0050] Furthermore, the shape and size of the container 1 can be set according to the heating chip 4, so that the heating chip 4 can fully contact the container 1 and dissipate heat. For example, the container 1 can be a hollow cuboid structure with the bottom surface consistent with the heating chip 4.

[0051] Preferably, the contact surface between the container 1 and the heating chip 4 is consistent with the size and shape of the heating chip 4.

[0052] Furthermore, the phase change cooling chip device also includes:

[0053] A thermally conductive silicone grease layer 3 is disposed between the container 1 and the heating chip 4 to fill the gap between the container 1 and the heating chip 4 and promote the heat transfer effect between the container 1 and the heating chip 4.

[0054] Preferably, the thermal grease layer 3 is a thermal grease with a thermal conductivity ≥3W / (mK).

[0055] Furthermore, the permanent magnet 5 is a thick, magnetized cubic magnet sheet. The normal operating temperature of the permanent magnet 5 needs to be significantly higher than the operating temperature of the phase change cooling chip device. Preferably, the permanent magnet 5 can be a neodymium iron boron magnet or a samarium cobalt magnet.

[0056] Furthermore, the Curie point temperature of the thermistor magnetic material is 5-15°C lower than the highest temperature of the heating chip 4 during normal operation, and is close to the phase transition temperature of the phase change material. This allows for effective cooling and temperature control of the heating chip 4.

[0057] Furthermore, the Curie point temperature of the thermosensitive magnetic material is less than or equal to the phase transition temperature of the phase transition material.

[0058] Preferably, the Curie point temperature of the thermosensitive magnetic material is lower than the phase transition temperature of the phase transition material.

[0059] More preferably, the difference between the phase transition temperature of the phase change material and the Curie point temperature of the thermistor magnetic material is less than or equal to 0.1 to 8°C.

[0060] Preferably, the thermistor magnetic material is a low Curie point material, such as low Curie point CuZnTi ferrite, low Curie point FeCrB amorphous alloy, and low Curie point Mn-Zn ferrite. The ferrite thermistor magnetic material selected in this application is generally insoluble in organic matter and does not produce chemical reactions. It can be mixed with most phase change materials and has a wide range of applications.

[0061] Preferably, the phase change material is a solid-liquid phase change material with good thermal conductivity, high phase change enthalpy, and good fluidity in the liquid state after phase change, such as organic phase change materials like paraffin, fatty acids, and fatty alcohols.

[0062] As some embodiments of this application, Table 1 below provides examples of several thermosensitive magnetic materials and phase change materials that constitute the composite material 2:

[0063] Table 1. Composition examples of composite material 2

[0064]

[0065] Among them, the (Fe) described in Table 1 70 Ni 30 ) 98 Cr2 can be nanoparticles prepared by ball milling, wherein (Fe 70 Ni 30 ) 89Zr7B4 can be an alloy powder prepared by ball milling and then water-cooled. In Table 1, when the same thermosensitive magnetic material corresponds to multiple phase change materials, one or more of them can be selected to prepare the composite material 2.

[0066] Furthermore, in the composite material 2, the mixing ratio of the thermosensitive magnetic material and the phase change material should be determined according to the specific circumstances, and will vary depending on the permanent magnet 5, the thermosensitive magnetic material, the phase change material, and the different applications.

[0067] Preferably, in the various combinations constituting the composite material 2, the volume ratio of each raw material component should be adjusted so that the magnetic force of the permanent magnet 5 on the composite material 2 at the initial start-up of the heating chip 4 is greater than twice the total weight of the composite material 2 and less than or equal to five times the total weight of the composite material 2. This ensures that the phase change cooling chip device has sufficient magnetic field driving force and sufficient latent heat of phase change to ensure the continuity of cooling during normal operation.

[0068] Furthermore, the preparation process of the composite material 2 is as follows:

[0069] First, the solid phase change material is heated until it is completely melted into a liquid state. Then, the thermosensitive magnetic material powder is added to the liquid phase change material while stirring, and the mixture is stirred until it has a uniform color. Heating is stopped, and stirring is continued. When it cools down to the point where it begins to solidify, stirring is stopped, and finally it is allowed to cool naturally to obtain the composite material.

[0070] As some embodiments of this application, the composite material 2 can be prepared directly in the container 1; or it can be prepared in other vessels and then poured into the container 1 before solidification.

[0071] Preferably, the composite material 2 is prepared using micron- or nano-scale thermosensitive magnetic material powder.

[0072] The working principle of the phase change cooling chip device based on thermomagnetic materials described in this application is explained below:

[0073] During the operation of the heating chip 4, as the heating chip 4 heats up, the solid phase change material near the heating chip 4 can first absorb the heat from the heating chip 4 through the thermally conductive silicone grease layer 3, and melt into a liquid state. At the same time, the temperature of the thermistor magnetic material in the composite material 2 reaches the Curie point, and the thermistor magnetic material completely loses its magnetism. Even in the constant magnetic field provided by the permanent magnet 5, there will be no downward attraction, but it will be suspended in the liquid phase change material. Therefore, at this time, the composite material 2 near the heating chip 4 can become a liquid composite material 2' with good fluidity. However, the phase change material farther away from the heating chip 4 has not yet started to undergo phase change and remains in a solid state because the heat absorption is insufficient. At the same time, the temperature of the thermistor magnetic material in the solid phase change material has not yet reached its Curie temperature, so it still has... Under the influence of the magnetic field, the solid composite material 2 at the far end moves towards the heating chip 4 and squeezes the liquid composite material 2' at the near end to the outside of the internal space of the container 1, and rises along the inner wall of the container 1. At this time, since the container 1 has a certain heat transfer capacity, the outer shell of the container 1 will heat up along with its bottom. Therefore, a temperature gradient distribution that decreases from bottom to top can be formed. The liquid composite material 2' that is squeezed up can experience this gradually decreasing temperature gradient during the rising process and be slowly cooled, but cannot be completely solidified until it is squeezed to the top of the container 1. Finally, through the heat transfer and cooling with the outside through the top of the container 1, it transforms back into solid composite material 2 and regains its magnetism, joining the next round of cooling queue. Then, the above steps are repeated continuously to form a cycle in the container 1.

[0074] In summary, the heat dissipation composite material and the phase change cooling chip device based on thermomagnetic materials described in this application have the following advantages:

[0075] First, this application utilizes the characteristic that the magnetism of thermistor magnetic materials decreases and eventually disappears as the temperature rises, and promotes dynamic and full contact between the phase change material and the heat-generating chip through magnetic force, thereby realizing a spontaneous enhanced phase change cooling chip process.

[0076] Second, the phase change cooling chip device based on thermomagnetic materials described in this application can independently achieve cyclic heat transfer through solid-liquid phase change flow, and has high thermal conductivity, excellent isothermal properties, and variable heat flux density.

[0077] Third, the phase change cooling chip device based on thermomagnetic materials described in this application avoids complex internal circuits and has the advantages of simple structural design and easy implementation.

[0078] In summary, the heat dissipation composite material and the phase change cooling chip device based on thermomagnetic material described in this application not only meet the need for recycling of non-open systems, but also enable the heat-generating chip to come into more full contact with the phase change material, while avoiding complex internal circuits. It has the advantages of simple structure, spontaneous circulation control and stable and reliable cooling effect, and can achieve simpler and more efficient cooling of highly integrated chips.

[0079] The following specific embodiments illustrate the heat dissipation composite material and the phase change cooling chip device based on thermomagnetic materials described in this application:

[0080] Example 1

[0081] like Figures 1-3 As shown, a phase change cooling chip device based on thermomagnetic materials includes a pure copper container 1, a composite material 2 filled in the container 1, a heating chip 4 connected to the bottom of the container 1, a thermally conductive silicone grease layer 3 between the container 1 and the heating chip 4, and a sheet-shaped permanent magnet 5 under the heating chip 4. The container 1 is a 30mm*30mm*40mm rectangular cavity structure with a wall thickness of 1mm; the heating chip 4 is a 30mm*30mm*2mm sheet-shaped cuboid; and the permanent magnet 5 is a 30mm*30mm*5mm neodymium magnet cuboid of type N35.

[0082] Composite material 2 is prepared by uniformly mixing CuZnTi magnetocaloric ferrite powder and No. 62 paraffin wax. The volume ratio of CuZnTi magnetocaloric ferrite powder to No. 62 paraffin wax is 1:24. Figure 4 Theoretical calculations show that the initial magnetic force to gravity ratio of the obtained composite material is 2.75, ensuring its normal operation. The specific steps for preparing composite material 2 are as follows: First, melt the paraffin wax and pour it into container 1. Continue heating the paraffin wax while slowly pouring in CuZnTi magnetocaloric ferrite powder while stirring until the mixture exhibits a uniform color. Stop heating and continue stirring until it cools and begins to solidify. This yields a relatively uniform composite material. The Curie point temperature of the CuZnTi magnetocaloric ferrite is 62℃ or slightly lower, and the phase transition temperature of paraffin wax (No. 62) is 62℃. This ensures that the CuZnTi magnetocaloric ferrite completely loses its magnetism after the paraffin phase transition, allowing the device to operate accurately at a suitable temperature.

[0083] like Figure 3As shown, when the heating chip is working, the temperature continuously rises. The heat is conducted to the bottom of the container through the highly thermally conductive silicone grease. Due to the high thermal conductivity of the copper that makes up the container, the outer shell of the container heats up along with the bottom, and its temperature decreases continuously with the increase of distance from the bottom of the container. That is, the temperature gradient formed gradually decreases from the bottom to the top of the container. At the same time, the heat from the container wall is conducted to the composite material in contact with the container and begins to absorb heat and heat up. This causes the composite material in contact with the container wall to reach the phase change temperature of 62°C first and undergo a phase change, absorbing heat and melting into a liquid state. At the same time, the thermosensitive magnetic material in it completely loses its magnetism and forms a liquid film that can flow on the surface of the container wall. The composite material in the place far from the container wall, that is, inside the container, does not reach 62°C because it does not absorb heat sufficiently, so it still has magnetism. Under the attraction of the external permanent magnet, the composite material at the bottom, which has undergone phase change, is squeezed downwards by the un-phase-changed composite material above. A layer of liquid composite material closer to the container wall is squeezed upwards to the top. The CuZnTi magnetocaloric ferrite nanopowder mixed in paraffin wax, due to its fine particles, also flows along with the relatively viscous paraffin wax, causing the un-phase-changed composite material to move downwards, making better contact with the bottom of the container and simultaneously cooling the heating chip more effectively, ensuring its temperature remains stable at 62°C. Due to the high thermal conductivity of copper, the outer shell of the container heats up along with the bottom, creating a temperature gradient that decreases from bottom to top. The squeezed liquid composite material experiences this temperature gradient and is slowly cooled, but cannot completely solidify until it is squeezed to the top. There, through the highly thermally conductive container wall and external heat transfer, it undergoes phase change back to a solid composite material, regaining its magnetism and joining the next cooling cycle. This cycle repeats continuously, allowing the device to improve the chip cooling rate while also meeting the requirements for a closed-loop system.

[0084] While the present invention has been disclosed above, it is not limited thereto. In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A composite material for heat dissipation, characterized in that, The composite material is composed of a thermosensitive magnetic material and a phase change material. The composite material flows through the action of magnetic force, dynamically contacting the target device that needs temperature control and enhancing its heat dissipation and cooling. The Curie point temperature of the thermosensitive magnetic material is 5-15°C lower than the highest temperature of the target device during normal operation. The Curie point temperature of the thermosensitive magnetic material is less than or equal to the phase change temperature of the phase change material. The phase change material is a solid-liquid phase change material.

2. The heat dissipation composite material according to claim 1, characterized in that, By adjusting the volume ratio of each raw material component, the magnetic force initially experienced by the composite material when starting the target device requiring temperature control is greater than or equal to twice the total weight of the composite material and less than or equal to five times the total weight of the composite material.

3. A phase change cooling chip device based on thermomagnetic materials, characterized in that, include: The composite material (2) as described in claim 1 or 2 above; A container (1) for holding the composite material (2); the container (1) is made of a non-magnetic metallic thermally conductive material. A magnetic force generating unit is used to provide a constant magnetic field for the composite material (2); the magnetic force generating unit is a sheet magnet with a thickness magnetized surface; The composite material (2) is filled in the container (1), and the container (1) is in contact with the target device that needs to be temperature controlled; A thermally conductive silicone grease layer (3) is disposed between the container (1) and the target device that needs to be temperature controlled, for filling the gap between the container (1) and the target device that needs to be temperature controlled; The composite material (2) generates flow through the attraction of magnetic force. The container (1) is placed on the upper side of the target device that needs to be temperature controlled. The bottom surface of the container (1) contacts the target device that needs to be temperature controlled. The magnetic force generating unit is placed on the lower side of the target device that needs to be temperature controlled.

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