Composite cooling fin and preparation method thereof

Abstract

The embodiment of the invention relates to the technical field of cooling fins, and discloses a composite cooling fin and a preparation method thereof.The composite cooling fin comprises a stacking body and a heat radiation coating, the stacking body is provided with heat radiation surfaces, and the heat radiation coating is at least coated on one heat radiation surface; the thermal radiation coating comprises 40%-60% of a resin base material, 20%-40% of an infrared radiation filler, 5%-10% of a curing agent and the balance of a solvent; the stacked body comprises substrate layers and solder layers, the solder layers are located between the adjacent substrate layers, and the adjacent substrate layers are tightly stacked together through the solder layers. The invention discloses a preparation method of a composite cooling fin. The preparation method comprises the following steps: preparing a stacking body; preparing a thermal radiation coating; a composite heat sink is made based on the stack and the thermal radiation coating. According to the technical scheme, the novel composite cooling fin can be manufactured, the composite cooling fin is good in cooling effect, and the problem that heat collected on the surface of the metal cooling fin is difficult to dissipate in time under the condition that convection is not carried out can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat sinks, and in particular to a composite heat sink and a preparation method thereof. Background Art

[0002] Laser welding of the cell top cover is one of the important links in the cell sealing welding process, and its laser welding quality will affect the safety and stability of cell use. During the laser welding process of the cell top cover, to ensure the strength and corrosion resistance of the weld, the laser welding machine heats the welding material at a high temperature to fully melt the welding material, and the heat generated during laser welding usually needs to be dissipated by a heat dissipation structure to ensure the stability and service life of the laser welding machine.

[0003] When the cell top cover is laser welded, heat can be located and conducted through the heat dissipation structure. Currently, the heat dissipation structure usually selects metal heat sinks, such as aluminum and aluminum-based alloys, copper and copper-based alloys, etc.

[0004] However, the surface heat radiation coefficient of the metal heat sink is low, and without convection, the heat accumulated on the surface of the metal heat sink is difficult to dissipate in time. Summary of the Invention

[0005] To solve the above problems, the invention purpose of the first aspect of the present application is to provide a composite heat sink, where heat is conducted at the stacked body and heat is radiated through the heat radiation coating, which is beneficial to improving the heat dissipation effect of the composite heat sink, so that the composite heat sink can still dissipate heat in time without convection.

[0006] The invention purpose of the second aspect of the present application is to provide a preparation method of a composite heat sink to obtain a composite heat sink with good thermal conductivity and high mechanical strength.

[0007] To achieve the above purpose, the present invention provides the following technical solutions: In the first aspect, a composite heat sink of the present invention includes a stacked body and a heat radiation coating. The stacked body has a heat dissipation surface facing the outside, and the heat radiation coating is at least coated on one of the heat dissipation surfaces; the heat radiation coating, by weight percentage, includes the following components: 40% - 60% of resin base material, 20% - 40% of infrared radiation filler, 5% - 10% of curing agent, and the balance is solvent; the stacked body includes a substrate layer and a solder layer, the solder layer is located between adjacent substrate layers and is tightly stacked with the adjacent substrate layers.

[0008] In the second aspect, a preparation method of a composite heat sink of the present invention includes the following steps: Apply solder on the surface of the substrate layer to obtain a solder layer; cover the substrate layer on the solder layer to obtain a stack in which the solder layer and the substrate layer overlap each other; mix the weighed resin base material, infrared radiation filler, curing agent and solvent to obtain a thermal radiation coating; apply the thermal radiation coating on the heat dissipation surface of the stack, and the thermal radiation coating cures to form a thermal radiation layer, and a composite heat sink is formed based on the stack and the thermal radiation layer.

[0009] In some implementation manners, before the step of applying solder on the surface of the substrate layer, it further includes: Mix the weighed base material, reinforcing material, binder and functional filler and ball mill them to obtain a composite slurry, and hot press the composite slurry to prepare a substrate layer.

[0010] In some implementation manners, the base material is any one or more of polyimide, polyphenylene sulfide, and polyether ether ketone; The reinforcing material is any one or more of carbon fiber, glass fiber, and carbon nanotube; The binder is any one or more of epoxy resin, polyurethane resin, and silicone resin; The functional filler is any one or more of aluminum, alumina, aluminum nitride, zinc oxide, and ceramic powder.

[0011] In some implementation manners, in the substrate layer, by weight percentage, the base material accounts for 40% - 70% of the substrate layer; the reinforcing material accounts for 20% - 50% of the substrate layer; the binder accounts for 5% - 15% of the substrate layer; the balance is the functional filler.

[0012] In some implementation manners, the infrared radiation filler is any one or more of nano-alumina, nano-zirconia, nano-silicon carbide, and nano-titanium dioxide.

[0013] In some implementation manners, the particle size of the nano-alumina is 10 nm - 50 nm, the particle size of the nano-zirconia is 20 nm - 100 nm, the particle size of the nano-silicon carbide is 30 nm - 500 nm, and the particle size of the nano-titanium dioxide is 20 nm - 100 nm.

[0014] In some implementation manners, the solder is any one or more of low-temperature solder, high-temperature solder, or metal solder powder, wherein the melting point of the low-temperature solder is 138°C - 190°C, and the melting point of the high-temperature solder is 217°C - 450°C.

[0015] In some implementation manners, the low-temperature solder is any one or more of Sn42Bi and Sn63Pb; The high-temperature solder is any one or more of SAC305 and SAC105; The metal solder powder is any one or more of Cu, Al, Sn, Zn, Ag, SnPb, SnAg, and SnZn.

[0016] In some implementation manners, in the composite heat sink, the thickness of the substrate layer is 40 ~200 and the thickness of the solder layer is 2 ~20 and the thickness of the heat radiation coating is 5 ~15 .

[0017] Based on the above technical solutions, the present invention has the following technical effects: 1. For the composite heat sink provided by the present invention, adjacent substrate layers are tightly connected through the solder layer, and the substrate layer and the solder layer are tightly stacked to form a stacked body, and the heat radiation coating is coated on the heat dissipation surface of the stacked body. When the composite heat sink dissipates heat, the tight combination of the substrate layer and the solder layer can conduct heat, which is beneficial to improving the thermal conductivity of the composite heat sink.

[0018] At the same time, the heat of the composite heat sink is concentrated at the heat dissipation surface and the heat radiation coating. The infrared active bonds of the infrared radiation filler in the heat radiation coating are excited by infrared radiation to generate vibrations. Based on the composite effect, the heat radiation coating quickly conducts the internal heat to the surface of the heat radiation coating and dissipates it outward through radiation, which helps to reduce the temperature of the composite heat sink. At this time, without convection, the composite heat sink can still dissipate the heat concentrated on the surface in time, ensuring the thermal stability of the composite heat sink during use.

[0019] 2. For the preparation method of the composite heat sink provided by the present invention, the solder layer is combined with the substrate layer through heat welding treatment to form a stacked body, and the heat radiation coating is coated and cured on the heat dissipation surface of the stacked body to form a heat radiation coating. The combination among the substrate layer, the solder layer, and the heat radiation coating is tight, which is beneficial to improving the mechanical properties and heat dissipation performance of the composite heat sink. Description of the Drawings

[0020] Figure 1 is a front view of a composite heat sink according to a specific embodiment of the present invention; Figure 2 is an overall structural schematic diagram of a composite heat sink according to a specific embodiment of the present invention.

[0021] Markings in the figure: 1. Substrate layer; 2. Solder layer; 3. Heat radiation coating; 4. Heat dissipation surface. Detailed Embodiments

[0022] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. The present invention provides preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0023] Before further describing various embodiments of the compounds / compositions and methods of the present disclosure in more detail by way of exemplary descriptions, examples, and results, it should be understood that the embodiments of the present disclosure are not limited in application to the details of the methods and compositions described in the following description. The description provided herein is for illustrative purposes only and is not to be construed in a limiting sense. The inventive concept of the present disclosure can have other embodiments or can be practiced or implemented in various ways. Therefore, the language used herein is intended to give the broadest scope and meaning; and the embodiments are intended to be exemplary and not exhaustive and are not intended to limit the present disclosure to these specific embodiments. Moreover, it should be understood that the wording and terminology employed herein are for descriptive purposes and should not be considered limiting unless otherwise indicated. In addition, in the following detailed description, many specific details are set forth in order to provide a more thorough understanding of the present disclosure.

[0024] However, it will be apparent to those of ordinary skill in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, features well known to those of ordinary skill in the art have not been described in detail to avoid unnecessary complication of the description. It is intended that all alternatives, substitutions, modifications, and equivalents that are apparent to those of ordinary skill in the art be included within the scope of the present disclosure. According to the present disclosure, all compounds / compositions and their preparation methods, applications, and uses disclosed herein can be prepared and implemented without undue experimentation.

[0025] Therefore, although the compounds / compositions and methods of the present disclosure have been described in accordance with specific embodiments, it will be apparent to those skilled in the art that changes can be made to the formulations, compounds or compositions and / or methods and to the steps or the order of steps of the methods described herein without departing from the spirit and scope of the inventive concept of the present disclosure.

[0026] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present disclosure shall have the meanings commonly understood by those of ordinary skill in the art. In addition, unless the context otherwise requires, singular terms shall include the plural and plural terms shall include the singular.

[0027] The following further elaborates on the present application.

[0028] A composite heat sink of the present invention includes a stacked body and a heat radiation coating 3. The stacked body has a heat dissipation surface 4 facing the outside, and the heat radiation coating 3 is coated on at least one of the heat dissipation surfaces 4. Among them, by weight percentage, the heat radiation coating 3 includes 40% - 60% of a resin base material, 20% - 40% of an infrared radiation filler, 5% - 10% of a curing agent, and the balance is a solvent; The stacked body includes a substrate layer 1 and a solder layer 2. The solder layer 2 is located between adjacent substrate layers 1 and is tightly stacked with the adjacent substrate layers 1. The substrate layer 1 and the solder layer 2 are alternately stacked. At this time, the heat dissipation surface 4 is the surface of the outermost substrate layer 1 in the stacked body.

[0029] A preparation method of a composite heat sink of the present invention is used to prepare the above composite heat sink, and includes the following steps: Mix the weighed base material, reinforcing material, binder, and functional filler, stir evenly to obtain a mixed material, and use a ball mill to ball mill the mixed material at a ball mill rotation speed of 200 r / min - 450 r / min and a ball milling time of 24 h - 36 h to prepare a uniform and stable composite slurry. The composite slurry is allowed to stand for 1 h - 2 h. After the bubbles in the composite slurry disappear, the composite slurry is hot-pressed into a substrate layer 1; Apply the solder of the solder layer 2 on the surface of the substrate layer 1, and cover another substrate layer 1 on the surface of the solder layer 2. Repeat the above steps to alternately stack the substrate layer 1 and the solder layer 2 to obtain a stacked body. After the stacked body is heated and welded and then cooled, it can become a stacked body with heat dissipation performance composed of multiple layers of substrate layers 1 and solder layers 2 intersecting.

[0030] Mix the weighed resin base material and solvent, stir evenly in a water bath environment at 50°C - 75°C until the resin base material dissolves. The resin base material gradually changes from a transparent color to milky white and finally becomes a transparent solution. Then add the weighed infrared radiation filler and curing agent to the dissolved resin base material and mix evenly to obtain a heat radiation slurry; Apply the heat radiation slurry on the heat dissipation surface 4, that is, apply the heat radiation slurry on the surface of the substrate layer 1. The heat radiation coating is cured to form a heat radiation coating 3 to prepare a composite heat sink. In a preferred embodiment, the curing temperature of the heat radiation coating in the oven is 70°C - 80°C, and the curing time is 4 h - 5 h. In some other specific embodiments, the stacked body coated with the heat radiation slurry can be cured at room temperature, and the curing time is 24 h - 36 h.

[0031] In a preferred embodiment, the resin base material can be an epoxy resin or a silicone resin. Specifically, when the resin base material is an epoxy resin, the curing agent can be selected from amine curing agents, anhydride curing agents, imidazole curing agents, etc. When the resin base material is a silicone resin, the curing agent can be selected from triethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, etc. It can be understood that this is not a specific limitation on the types of curing agents, and the curing agent is used in combination with the resin base material.

[0032] In a preferred embodiment, the infrared radiation filler can be one or more of nano-aluminum oxide, nano-zirconium oxide, nano-silicon carbide, and nano-titanium dioxide, such as a mixture of nano-aluminum oxide and nano-titanium dioxide, a mixture of nano-zirconium oxide and nano-silicon dioxide, or a single nano-zirconium oxide. In some specific embodiments shown, the infrared radiation filler needs to be selected with a suitable particle size range. If the particle size of the infrared radiation filler is small, it will increase the process cost; but if the particle size of the infrared radiation filler is large, it is not easy to penetrate the cracks and holes of the main material, thereby affecting the heat dissipation performance of the composite heat sink produced. Therefore, an infrared radiation filler with an appropriate particle size can obtain the best mechanical properties. When selecting the particle size of the infrared radiation filler, it specifically includes: the particle size of nano-aluminum oxide is 10 nm to 50 nm, such as 10 nm, 25 nm, 30 nm, 45 nm, 50 nm, etc.; the particle size of the nano-zirconium oxide is 20 nm to 100 nm, such as 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, etc.; the particle size of the nano-silicon carbide is 30 nm to 500 nm, such as 30 nm, 100 nm, 250 nm, 450 nm, 500 nm, etc.; the particle size of nano-titanium dioxide is 20 nm to 100 nm, such as 20 nm, 40 nm, 55 nm, 70 nm, 100 nm, etc.

[0033] The infrared radiation filler can be uniformly dispersed in the resin base material, and the thermal radiation coating 3 can effectively dissipate the heat collected on the heat dissipation surface 4 in the form of thermal radiation. The high radiation rate and low absorption rate of the thermal radiation coating 3 enable the heat dissipation surface 4 to dissipate heat in a timely manner.

[0034] In some specific embodiments shown, the solvent can be selected from n-butanol, dimethylformamide, tetrahydrofuran, etc. Specifically, the solvent can be selected according to the type of the resin base material. When the resin base material is an epoxy resin, n-butanol can be used as the solvent, and when the resin base material is a silicone resin, dimethylformamide or tetrahydrofuran can be used as the solvent.

[0035] In a preferred embodiment, the thickness of the substrate layer 1 is 40 ~200 . Among them, if the thickness of the substrate layer 1 is less than 40 , the substrate is prone to deformation and cannot be mechanically operated. However, if the thickness of the substrate layer 1 is greater than 200 , it is difficult to compact the inside of the substrate, and the texture of the substrate is uneven; the thickness of the solder layer 2 is 2 ~20 , wherein, if the thickness of the solder layer is less than 2 , resulting in a poor bonding force between the solder and the substrate layer 1. If the thickness of the solder layer exceeds 20μm, the thermal resistance will increase, affecting the heat conduction effect; the thickness of the thermal radiation coating 3 is 5 ~15 , wherein, if the thickness of the thermal radiation coating 3 is less than 5μm, its heat dissipation ability will decrease, and it is more vulnerable to mechanical damage and environmental factors, resulting in reduced durability, and the too thin coating cannot provide sufficient adhesion; however, if the thickness of the thermal radiation coating 3 exceeds 15μm, the thermal resistance will increase, affecting the heat conduction effect, and the thick coating may dry unevenly, and there may be incompletely cured areas inside, affecting the overall performance. The thickness of the composite heat sink is 0.2mm - 5mm. If the thickness of the composite heat sink is too low, its strength is poor. If the thickness is too thick, it is not suitable for processing and application. The thickness of each layer of the composite heat sink is appropriate, which not only ensures the firm bonding force between the layers, but also reduces the thermal resistance, thereby improving the heat conduction performance of the composite heat sink. In some specific embodiments shown, both the substrate layer 1 and the solder layer 2 are provided with multiple layers, and the substrate layer 1 and the solder layer 2 are alternately stacked to form a stacked body, and the stacked body has good mechanical strength to reduce mechanical damage to the stacked body.

[0036] In a preferred embodiment, the substrate layer 1 includes 40% - 70% of a base material, 20% - 50% of a reinforcing material, 5% - 15% of a binder, and the balance is a functional filler. In some specific embodiments shown, the base material can be one or more of polyimide, polyphenylene sulfide, and polyether ether ketone, such as a mixture of polyphenylene sulfide and polyether ether ketone, a single polyimide, etc.

[0037] The functional filler can be one or more of aluminum, aluminum oxide, aluminum nitride, zinc oxide, and ceramic powder, such as a mixture of aluminum oxide and aluminum nitride, a single aluminum oxide, a single ceramic powder, etc. The addition of the functional filler is beneficial to improving the heat conduction efficiency of the substrate layer 1. When the substrate layer 1 contacts the high-temperature battery cell top cover and absorbs heat, the functional filler can conduct the heat to the solder layer 2 or dissipate it to the outside of the composite heat sink, so that the temperature of the substrate layer 1 is reduced, achieving the heat dissipation effect.

[0038] Further, the reinforcing material can be one or more of carbon fiber, glass fiber, and carbon nanotubes, such as carbon fiber and carbon nanotubes, single glass fiber, etc. The binder can be one or more of epoxy resin, polyurethane resin, and silicone resin, such as a mixture of epoxy resin and polyurethane resin, single silicone resin, etc. The reinforcing material, the substrate material, the adhesive, and the functional filler play a synergistic role, which is beneficial to improving the mechanical strength of the composite heat sink and further extending the service life of the composite heat sink.

[0039] In a preferred embodiment, the solder layer 2 can be one or more of a low-temperature solder layer, a high-temperature solder layer, or a metal solder powder layer. Among them, the melting point of the low-temperature solder layer is 138°C to 190°C, and the melting point of the high-temperature solder layer is 217°C to 450°C. Specifically, the low-temperature solder layer can use low-temperature solder paste, such as Sn42Bi, Sn63Pb, etc.; the high-temperature solder layer can use high-temperature solder paste, such as SAC305, SAC105, etc., and the metal solder powder layer can use one or more of metal powders such as Cu, Al, Sn, Zn, Ag, etc. and alloy powders. The alloy powders can be SnPb, SnAg, SnZn, etc. The solder layer 2 ensures the bonding stability between adjacent substrate layers 1 while transferring heat between adjacent substrate layers 1, improving the heat dissipation performance of the composite heat sink.

[0040] During the laser welding process of the battery cell top cover, the substrate layer 1 is in contact with the high-temperature battery cell top cover, and heat can be transferred and dissipated outward through the substrate layer 1 and the solder layer 2. When the heat is transferred to the heat dissipation surface 4 and the heat radiation coating 3, the infrared radiation filler in the heat radiation coating 3 conducts the internal heat to the surface of the heat radiation coating 3 and dissipates it outward by radiation. Even when there is no air convection, the heat on the surface of the composite heat sink can be dissipated in time, ensuring the heat dissipation performance of the composite heat sink and thus improving the problem that the battery cell top cover is prone to overheating.

[0041] Example 1 A composite heat sink includes a stacked body and a heat radiation coating 3. The stacked body has a heat dissipation surface 4 facing the outside, and the heat radiation coating 3 is coated on the heat dissipation surface 4. Among them, by weight percentage, the heat radiation coating 3 includes 40% epoxy resin, 40% mixture of nano silicon carbide and nano titanium dioxide, 5% amine curing agent, and the balance is n-butanol. The particle size of the nano silicon carbide is 30nm, and the particle size of the nano titanium dioxide is 100nm; the substrate layer 1 includes 70% polyimide, 20% carbon fiber, 15% epoxy resin, and the balance is a mixture of alumina and zinc oxide; the solder layer 2 is Sn42Bi solder paste with a melting point of 138°C.

[0042] The stacked body includes a substrate layer 1 and a solder layer 2. The solder layer 2 is located between adjacent substrate layers 1 and is tightly stacked with adjacent substrate layers 1. The thickness of the substrate layer 1 is 40 , the thickness of the solder layer 2 is 20 , the thickness of the heat radiation coating 3 is 5 , the thickness of the composite heat sink is 1.85 mm.

[0043] The preparation method of the above composite heat sink includes the following steps: Mix the weighed polyimide, carbon fiber, epoxy resin, alumina and zinc oxide, stir evenly to obtain a mixed material, use a ball mill to ball mill the mixed material, the ball milling speed is 200 r / min, and the ball milling time is 36 h to prepare a uniform and stable composite slurry. Let the composite slurry stand for 1 h. After the bubbles in the composite slurry disappear, hot press the composite slurry to form the substrate layer 1; Coat solder on the surface of the substrate layer 1 to obtain the solder layer 2, cover another layer of the substrate layer 1 on the surface of the solder layer 2, repeat the above steps to alternately stack the substrate layer 1 and the solder layer 2 to obtain a stack, and heat and weld the stack and then cool it; Stir the weighed epoxy resin and n-butanol evenly in a 50°C water bath environment until the epoxy resin dissolves. The epoxy resin gradually changes from transparent to milky white and finally becomes a transparent solution. Then add the weighed nano silicon carbide, nano titanium dioxide and amine curing agent to the dissolved epoxy resin, mix evenly to obtain a heat radiation slurry; Coat the heat radiation slurry on the heat dissipation surface 4, and the heat radiation coating cures to form the heat radiation coating 3, and the composite heat sink is prepared. The curing temperature of the heat radiation coating in the oven is 70°C, and the curing time is 5 h.

[0044] Example 2 A composite heat sink includes a stack and a heat radiation coating 3. The stack has a heat dissipation surface 4 facing the outside world, and the heat radiation coating 3 is coated on the heat dissipation surface 4. Among them, by weight percentage, the heat radiation coating 3 includes a mixture of 60% epoxy resin, 20% nano zirconia, 10% amine curing agent, and the balance is n-butanol. The particle size of the nano zirconia is 50 nm; the substrate layer 1 includes 40% polyphenylene sulfide, 50% glass fiber, 5% polyurethane resin, and the balance is a mixture of aluminum and aluminum nitride; the solder layer 2 is SAC105 solder paste, and its melting point is 228°C.

[0045] The stack includes a substrate layer 1 and a solder layer 2. The solder layer 2 is located between adjacent substrate layers 1 and is tightly stacked with the adjacent substrate layers 1. The thickness of the substrate layer 1 is 200 , the thickness of the solder layer 2 is 2 , the thickness of the heat radiation coating 3 is 15 , the thickness of the composite heat sink is 4.19 mm.

[0046] The preparation method of the above composite heat sink includes the following steps: Mix the weighed polyphenylene sulfide, glass fiber, polyurethane resin, aluminum, and aluminum nitride, stir evenly to obtain a mixed material, and use a ball mill to ball mill the mixed material at a ball milling speed of 450 r / min for 24 h to prepare a uniform and stable composite slurry. Let the composite slurry stand for 2 h. After the bubbles in the composite slurry disappear, hot press the composite slurry to prepare the substrate layer 1; Coat the surface of the substrate layer 1 with solder to obtain the solder layer 2, and cover another substrate layer 1 on the surface of the solder layer 2. Repeat the above steps to alternately stack the substrate layer 1 and the solder layer 2 to obtain a stacked body, and heat and weld the stacked body and then cool it; Mix the weighed epoxy resin and n-butanol, stir evenly in a water bath environment at 75 °C until the epoxy resin dissolves. The epoxy resin gradually changes from transparent to milky white and finally becomes a transparent solution. Then add the weighed nano-zirconia and amine curing agent to the dissolved epoxy resin and mix evenly to obtain a heat radiation slurry; Coat the heat radiation slurry on the heat dissipation surface 4, and the heat radiation coating cures to form the heat radiation layer 3, and a composite heat sink is prepared. The curing temperature of the heat radiation coating in the oven is 80 °C, and the curing time is 4 h.

[0047] Example 3 A composite heat sink includes a stacked body and a heat radiation layer 3. The stacked body has a heat dissipation surface 4 facing the outside world, and the heat radiation layer 3 is coated on the heat dissipation surface 4. Among them, by weight percentage, the heat radiation layer 3 includes a mixture of 50% epoxy resin, 35% nano-aluminum oxide, 8% amine curing agent, and the balance is n-butanol. The particle size of the nano-aluminum oxide is 40 nm; the substrate layer 1 includes 55% polyether ether ketone, 35% carbon nanotubes, 5% polyurethane resin, and the balance is zinc oxide; the solder layer 2 is SnPb alloy powder with a melting point of 138 °C.

[0048] The stacked body includes a substrate layer 1 and a solder layer 2. The solder layer 2 is located between adjacent substrate layers 1 and is tightly stacked with the adjacent substrate layers 1. The thickness of the substrate layer 1 is 110 , and the thickness of the solder layer 2 is 15 , and the thickness of the heat radiation layer 3 is 10 , and the thickness of the composite heat sink is 3.7 mm.

[0049] The preparation method of the above composite heat sink includes the following steps: Mix the weighed polyphenylene sulfide, glass fiber, polyurethane resin, aluminum, and aluminum nitride, stir evenly to obtain a mixed material, and use a ball mill to ball mill the mixed material at a ball milling speed of 300 r / min for 30 h to prepare a uniform and stable composite slurry. Let the composite slurry stand for 1.5 h. After the bubbles in the composite slurry disappear, hot press the composite slurry to prepare the substrate layer 1; Apply solder on the surface of the substrate layer 1 to obtain the solder layer 2. Then cover another substrate layer 1 on the surface of the solder layer 2. Repeat the above steps to alternately stack the substrate layer 1 and the solder layer 2 to obtain a stack. After heating and welding the stack, cool it down; Weigh epoxy resin and n-butanol, stir them evenly in a 60 °C water bath until the epoxy resin dissolves. The epoxy resin gradually changes from transparent to milky white and finally becomes a transparent solution. Then add the weighed nano-zirconia and amine curing agent to the dissolved epoxy resin and mix them evenly to obtain the heat radiation slurry; Apply the heat radiation slurry on the heat dissipation surface 4. The heat radiation coating cures to form the heat radiation layer 3, and a composite heat sink is prepared. The curing temperature of the heat radiation coating in the oven is 73 °C and the curing time is 4.5 h.

[0050] Example 4 The difference between Example 4 and Example 2 is that the particle size of the nano-zirconia is 150 nm.

[0051] Example 5 The difference between Example 5 and Example 3 is that the thickness of the substrate layer 1 is 25 , the thickness of the solder layer 2 is 1 , and the thickness of the heat radiation layer 3 is 3 .

[0052] Example 6 The difference between Example 6 and Example 3 is that the thickness of the substrate layer 1 is 300 , the thickness of the solder layer 2 is 35 , and the thickness of the heat radiation layer 3 is 20 .

[0053] Example 7 The difference between Example 7 and Example 3 is that the solder layer 2 is a hard soldering paste layer, and the melting point of the hard soldering paste layer is 595 °C.

[0054] Comparative Example 1 Comparative Example 1 uses a metal heat sink, which is a copper-based alloy heat sink with a thickness of 1 mm.

[0055] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that the composite heat sink does not have a heat radiation layer. Apply the solder of the solder layer 2 on the surface of the substrate layer 1, then cover another substrate layer 1 on the surface of the solder layer 2. Repeat the above steps to alternately stack the substrate layer 1 and the solder layer 2 to obtain a stack. After heating and welding the stack, cool it down to prepare the composite heat sink.

[0056] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that the composite heat sink is not provided with a solder layer 2, the heat radiation layer is coated on the surface of the substrate layer 1, the heat radiation coating is cured to form a heat radiation coating 3, and the composite heat sink is obtained.

[0057] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that the composite heat sink is not provided with a solder layer 2, the heat radiation layer is coated on the surface of the substrate layer 1, wherein the heat radiation coating 3 comprises a mixture of 50% epoxy resin, 35% nano-aluminum oxide, 8% amine curing agent, 5% zinc oxide, and the balance is n-butanol, and the particle size of the nano-aluminum oxide is 40 nm; the substrate layer 1 comprises 55% polyetheretherketone, 35% carbon nanotubes, and the balance is polyurethane resin.

[0058] Comparative Example 5 The difference between Comparative Example 5 and Example 3 is that no reinforcing material is added to the substrate layer 1, and the substrate layer 1 comprises 55% polyetheretherketone, 5% polyurethane resin, and the balance is zinc oxide.

[0059] Performance Test Thermal conductivity test: The thermal conductivity of the composite heat sinks prepared in Examples 1-7 and Comparative Examples 1-5 was tested and detected according to the internationally common ASTM-E1461 standard for thermal conductivity testing.

[0060] Tensile property test: The tensile strength of the composite heat sinks prepared in Examples 1-7 and Comparative Examples 1-5 was tested and detected according to ISO527-1-2012 Plastics - Determination of tensile properties; Flexural property test: The flexural strength of the composite heat sinks prepared in Examples 1-7 and Comparative Examples 1-5 was tested and detected according to ISO527-2 Plastics - Determination of tensile properties; Heat radiation test: The heat dissipation efficiency of the composite heat sink samples prepared in Examples 1-7 and Comparative Examples 1-5 was detected. The area of the composite heat sink samples was 30×3 mm, and heating was carried out with a heating power of 6 W to measure the temperatures of the top surface of the heat radiation coating 3 and the bottom surface of the substrate layer 1.

[0061] Test Results

[0062] Table 1 Performance test results of the composite heat sinks prepared in Examples 1-7 and Comparative Examples 1-5 Refer to Figure 1 and Figure 2, The composite heat sink forms a tightly combined multi-layer structure. From the comparison of the performance test results of Examples 1-3 and Comparative Examples 1-4 in Table 1, it can be seen that the composite heat sink has relatively high thermal conductivity, tensile strength and bending strength, a large temperature difference between the top surface temperature and the bottom surface temperature, and the composite heat sink exhibits good heat conduction efficiency and mechanical properties, and can enhance the heat dissipation performance through thermal radiation. Among them, in the thermal radiation test of the copper-based alloy heat sink in Comparative Example 1, the temperature difference between the top surface temperature and the bottom surface temperature is small, and the heat collected on the top surface of the copper-based alloy heat sink is difficult to dissipate in time, while the composite heat sink radiates heat through the thermal radiation coating, which is beneficial to timely heat dissipation.

[0063] When the substrate layer 1 contacts the high-temperature battery cell top cover, while the heat is dissipated at the substrate layer 1 and the solder layer 2 respectively, the heat can be conducted from the substrate layer 1 through the solder layer 2 to the heat dissipation surface 4 and the thermal radiation coating 3. The infrared active bonds of the infrared radiation fillers in the thermal radiation coating 3 are excited by infrared radiation to generate vibrations. The thermal radiation coating 3 quickly conducts the internal heat to the surface of the thermal radiation coating 3 and dissipates it outward in a radiation manner. The composite heat sink can effectively improve the problem that the traditional metal heat sink is prone to heat accumulation on the surface. The composite heat sink can dissipate heat in time without convection to ensure thermal stability, and the composite heat sink can be used in high-temperature environments.

[0064] According to the comparison of the performance test results of the composite heat sinks prepared in Example 2 and Example 4, it can be known that the particle size of the infrared radiation filler has an impact on both the radiation heat dissipation effect and the mechanical properties of the thermal radiation coating 3. When the particle size of the infrared radiation filler is too large, the infrared radiation filler is difficult to be evenly distributed in the resin matrix, and it is easy to form defects or stress concentration points in the thermal radiation coating 3, and the thermal radiation coating 3 is prone to peeling off and the heat dissipation efficiency is reduced.

[0065] According to the comparison of the performance test results of the composite heat sinks prepared in Examples 3-6, it can be known that there is a synergistic effect between the substrate layer 1, the solder layer 2 and the thermal radiation coating 3, and the thickness of each layer of the composite heat sink will have an impact on the heat conduction performance and mechanical properties.

[0066] Among them, when the thickness of the substrate layer 1 is less than 40 , it is easy to deform and difficult to perform mechanical operations. When the thickness of the substrate layer 1 is greater than 200 , the internal compaction of the composite heat sink is uneven; when the thickness of the solder layer 2 is less than 2 , the bonding force of the solder layer 2 bonding the adjacent substrate layer 1 is poor. When the thickness of the solder layer 2 is greater than 20 , the too large thickness of the solder layer 2 will increase the thermal resistance and affect the heat conduction effect inside the composite heat sink; when the thickness of the thermal radiation coating 3 is less than 5 When the heat radiation capacity of the composite heat sink decreases, it is more vulnerable to mechanical damage and environmental factors. The adhesion of the heat radiation layer 3 to the heat dissipation surface 4 decreases, resulting in a decline in durability. The thickness of the heat radiation coating 3 is greater than 15 When the heat radiation coating 3 is in this state, there may be an uneven drying and curing situation, resulting in areas that are not fully cured inside, affecting the overall performance of the composite heat sink, increasing the thermal resistance, and reducing the efficiency of heat conduction.

[0067] According to the comparison of the performance test results of the composite heat sinks prepared in Example 3 and Example 7, it can be seen that the melting point of the solder layer 2 affects the overall heat dissipation effect and mechanical properties of the composite heat sink. When the melting point of the solder layer 2 is too high, the thermal conductivity of the composite heat sink decreases. At the same time, the high strength of the solder layer 2 can affect the overall processing performance of the composite heat sink.

[0068] According to the comparison of the performance test results of the composite heat sinks prepared in Example 3 and Comparative Example 3, it can be seen that the solder layer 2 can improve the bonding force between adjacent substrate layers 1. At the same time, it is beneficial to the heat conduction between the substrate layers 1, making the composite heat sink have the characteristics of good thermal conductivity, mechanical strength, and light weight.

[0069] According to the comparison of the performance test results of the composite heat sinks prepared in Example 3 and Comparative Example 5, it can be seen that the reinforcing material is beneficial to improving the flexural strength and tensile strength of the substrate layer 1, and thus improving the overall mechanical properties of the composite heat dissipation layer.

[0070] The above content is only an example and explanation of the structure of the present invention. Its description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these obvious replacement forms all belong to the protection scope of the present invention.

Claims

1. A composite heat sink, characterized in that: It comprises a stacked body and a heat radiation coating (3), wherein the stacked body has a heat dissipation surface (4) facing the outside, and the heat radiation coating (3) is coated on at least one of the heat dissipation surfaces (4); The thermal radiation coating (3) comprises the following components by weight percentage: 40% to 60% of a resin base material, 20% to 40% of an infrared radiation filler, 5% to 10% of a curing agent, and the balance being a solvent; The stacked body comprises a substrate layer (1) and a solder layer (2), wherein the solder layer (2) is located between adjacent substrate layers (1) and is tightly stacked with the adjacent substrate layers (1).

2. A method for preparing a composite heat sink, used for preparing the composite heat sink according to claim 1, characterized in that: The following steps are involved: Coating solder on the surface of the substrate layer to obtain a solder layer; Covering the substrate layer on the solder layer to obtain a stacked body in which the solder layer and the substrate layer overlap each other; Mixing weighed resin base material, infrared radiation filler, curing agent and solvent to obtain thermal radiation coating; The heat radiation coating is coated on the heat dissipation surface of the stacked body, the heat radiation coating is cured to form a heat radiation coating, and a composite heat sink is formed based on the stacked body and the heat radiation coating.

3. The method for preparing the composite heat sink according to claim 2, characterized in that: Before the step of coating the solder on the surface of the substrate layer, the method further comprises: The weighed base material, reinforcing material, adhesive and functional filler are mixed and ball-milled to obtain a composite slurry, and the composite slurry is hot-pressed to obtain a substrate layer.

4. The method for preparing the composite heat sink according to claim 3, characterized in that: The base material is any one or more of polyimide, polyphenylene sulfide, and polyetheretherketone; The reinforcing material is any one or more of carbon fiber, glass fiber and carbon nanotube; The binder is any one or more of epoxy resin, polyurethane resin and silicone resin; The functional filler is any one or more of aluminum, aluminum oxide, aluminum nitride, zinc oxide and ceramic powder.

5. The method for preparing the composite heat sink according to claim 3, characterized in that: In the substrate layer, by weight percentage, the base material accounts for 40% to 70% of the substrate layer; the reinforcing material accounts for 20% to 50% of the substrate layer; the adhesive accounts for 5% to 15% of the substrate layer; and the remainder is functional filler.

6. The method for preparing the composite heat sink according to claim 2, characterized in that: The infrared radiation filler is any one or more of nano-alumina, nano-zirconium oxide, nano-silicon carbide and nano-titanium dioxide.

7. The method for preparing the composite heat sink according to claim 6, characterized in that: The particle size of the nano-alumina is 10 nm to 50 nm, the particle size of the nano-zirconium oxide is 20 nm to 100 nm, the particle size of the nano-silicon carbide is 30 nm to 500 nm, and the particle size of the nano-titanium dioxide is 20 nm to 100 nm.

8. The method for preparing a composite heat sink according to claim 2, characterized in that: The solder is any one or more of low-temperature solder, high-temperature solder or metal solder powder, wherein the melting point of the low-temperature solder is 138°C to 190°C, and the melting point of the high-temperature solder is 217°C to 450°C.

9. The method for preparing the composite heat sink according to claim 8, characterized in that: The low temperature solder is any one or more of Sn42Bi and Sn63Pb; The high temperature solder is any one or more of SAC305 and SAC105; The metal solder powder is any one or more of Cu, Al, Sn, Zn, Ag, SnPb, SnAg and SnZn.

10. The method for preparing a composite heat sink according to claim 2, characterized in that: In the composite heat sink, the thickness of the substrate layer is 40 ~200 , the thickness of the solder layer is 2 ~20 The thickness of the thermal radiation coating is 5 ~15 .

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