Heat dissipation coating structure and electronic components and electronic devices using that structure

Abstract

To provide a heat-dissipating coating structure having excellent heat-dissipating properties and durability.SOLUTION: In a heat-dissipating coating film structure that is a planar structure composed of at least heat-dissipating particles and a resin, the heat-dissipating particles are particles having an average particle size of 0.1 to 30 μm, composed of an oxide containing at least two elements selected from aluminum, magnesium, and silicon, and the average thickness of the heat-dissipating coating structure is at least 10 times the average particle diameter of the heat-dissipating particles, and the surface of the heat-dissipating coating structure has a plurality of recesses, and a plurality of heat-dissipating particles are exposed on the surfaces of the recesses.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a heat radiating coating film structure capable of radiating heat of a heating element to the outside by heat radiation, and an electronic member and an electronic device including the heat radiating coating film structure.

Background Art

[0002] In recent years, with the miniaturization and high density of power devices and semiconductor packages, the heat generation density of devices has been increasing. Therefore, in the electronic members mounted in the device, it is essential to efficiently radiate the heat generated from each electronic member so as not to exceed the operating guarantee temperature.

[0003] As heat radiating means, generally, fins using convection and heat conduction sheets using heat conduction are used. However, it has been difficult to radiate heat to below the operating guarantee temperature of a heating element such as a heat generating device included in a device only with such conventional heat countermeasure members as heat radiating means. In recent years, as means capable of radiating heat without securing space, heat radiating paints, heat radiating coating films, and sheets and members having a heat radiating coating film formed on the surface have attracted attention.

[0004] FIG. 8 is a cross-sectional view showing a cross-sectional structure of a structure having a planar shape (hereinafter referred to as "heat radiating coating film structure 33") formed on a base material 31 by a conventional method described in Patent Document 1, for example. As shown in FIG. 8, the heat radiating coating film structure 33 is composed of a resin 30 and heat transfer particles 32, and heat from the base material 31 is mainly transferred in the thickness direction within the heat radiating coating film structure 33 by the heat transfer particles 32 present in the heat radiating coating film structure 33, and is radiated from the surface of the heat radiating coating film structure 33. At this time, by containing a certain amount of heat transfer particles 32 having a large particle diameter in the heat radiating coating film structure 33, unevenness is formed on the surface of the heat radiating coating film structure 33, and the heat radiating performance is improved by increasing the surface area.

[0005] Figure 9 is a cross-sectional view showing the cross-sectional structure of a heat-dissipating coating structure 35 fabricated on a substrate 31 by a conventional method described in, for example, Patent Document 2. An outermost layer 34 containing radioactive particles 36 is formed on the outermost surface of the particle-containing film. By including radioactive particles 36 having a particle diameter larger than the thickness of the outermost layer 34, a portion of the radioactive particles 36 are exposed from the outermost layer 34, increasing the radiation from the surface of the radioactive particles 36, thereby promoting the removal of heat transferred from the substrate 31 and improving heat dissipation performance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] WO2009-142036 publication [Patent Document 2] Japanese Patent Publication No. 2006-281514 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The method for manufacturing the heat dissipation coating structure 33 described in Patent Document 1 involves mixing heat transfer particles 32 with a resin 30 or a resin component which is a raw material for the resin 30, and a solvent that dissolves the resin component, coating the mixture onto the surface of a substrate 31, and then drying and curing it (hereinafter, this manufacturing method will be referred to as "wet coating").

[0008] However, with this method, a film of resin 30 is formed on the outermost surface of the heat dissipation coating structure 33, reducing the heat transfer performance in the thickness direction near the surface of the heat dissipation coating structure 33, as well as the radiation performance from the surface. In addition, resin 30 penetrates between adjacent heat transfer particles 32, reducing heat transfer within the heat dissipation coating structure 33, resulting in insufficient heat dissipation performance of the heat dissipation coating structure 33. Furthermore, in order to ensure heat transfer within the heat dissipation coating structure 33 and to arrange the heat transfer particles 32 near the surface of the heat dissipation coating structure 33 to improve radiation, it is necessary to include a large amount of heat transfer particles 32. As a result, the resin component content decreases, leading to problems such as cracking of the heat dissipation coating structure 33 and peeling from the substrate 31 due to expansion and contraction due to temperature changes and external stresses applied to the heat dissipation coating structure 33.

[0009] Patent Document 2 describes a problem in which radioactive particles 36 protrude from the outermost layer 34 of the heat dissipation coating structure 35, making it easy for the radioactive particles 36 to detach due to wear and abrasion, thus reducing the durability of the heat dissipation coating structure.

[0010] Therefore, the purpose of this disclosure is to provide a heat-dissipating coating structure that has excellent heat dissipation properties and durability. [Means for solving the problem]

[0011] To achieve the above objective, the heat dissipation coating structure according to this disclosure is a planar structure composed of at least heat dissipating particles and a resin, wherein the heat dissipating particles are particles with an average particle diameter of 0.1 to 30 μm, composed of oxides containing at least two elements selected from aluminum, magnesium, and silicon, the average thickness of the heat dissipation coating structure is 10 times or more the average particle diameter of the heat dissipating particles, and multiple recesses exist on the surface of the heat dissipation coating structure, with multiple heat dissipating particles exposed on the surface of the recesses.

[0012] Furthermore, the electronic component relating to this disclosure has the above-mentioned heat dissipation coating structure formed on its surface.

[0013] Furthermore, the electronic device relating to this disclosure has the above-mentioned heat dissipation coating structure formed on its surface.

[0014] In addition, the method for manufacturing a heat dissipation coating film structure according to the present disclosure includes a compounding treatment step of forming composite particles in which heat dissipating particles are coated on the surface of powder composed of at least a thermoplastic resin or a thermosetting resin, a powder layer forming step of forming a powder layer in which the composite particles are laminated, an arranging step of reducing the voids in the powder layer by pressing or heating the powder layer and arranging the composite particles to form an arranged layer, and a heat curing step of forming a heat dissipation coating film structure by once melting the resin by heating the arranged layer and then cooling it.

Effects of the Invention

[0015] The heat dissipation coating film structure according to the present disclosure can provide a heat dissipation coating film structure that is excellent in heat dissipation performance, reduces the degradation of heat dissipation performance due to wear and friction, and has resistance to stress generated by temperature changes and external loads.

Brief Description of the Drawings

[0016] [Figure 1] It is a cross-sectional view showing the cross-sectional structure of the heat dissipation coating film structure according to Embodiment 1. [Figure 2] It is a cross-sectional view showing the manufacturing method of the heat dissipation coating film structure in the embodiment. [Figure 3] It is a cross-sectional view showing the cross-sectional structure of an electronic component in the embodiment. [Figure 4] It is a view showing the cross-sectional structure of an electronic device in the embodiment. [Figure 5] It is a cross-sectional view showing the cross-sectional structure of the heat dissipation performance evaluation elements in Comparative Example 1 and Examples 1 to 20. [Figure 6] It is a cross-sectional view showing the cross-sectional structure of the heat dissipation performance evaluation element in Comparative Example 2. [Figure 7] It is a cross-sectional view showing the configuration of the temperature rise suppression temperature change evaluation device. [Figure 8] It is a cross-sectional view showing the cross-sectional structure of the heat dissipation coating film structure in Patent Document 1. [Figure 9] It is a cross-sectional view showing the cross-sectional structure of the heat dissipation coating film structure in Patent Document 2. [Figure 10] Table 1 showing the detailed content of the heat dissipation coating film structures produced in the examples and comparative examples. [Figure 11] Table 2 showing the effects of the actual heat dissipation performance for some of the comparative examples and examples.

Mode for Carrying Out the Invention

[0017] The heat dissipation coating film structure according to the first aspect is a heat dissipation coating film structure which is a planar structure composed of at least heat dissipating particles and a resin. The heat dissipating particles are particles with an average particle diameter of 0.1 to 30 μm composed of an oxide containing at least two elements selected from aluminum, magnesium, and silicon. The average thickness of the heat dissipation coating film structure is 10 times or more the average particle diameter of the heat dissipating particles. A plurality of recesses exist on the surface of the heat dissipation coating film structure, and a plurality of heat dissipating particles are exposed on the surface of the recesses.

[0018] The heat dissipation coating film structure according to the second aspect is, in the first aspect, the depth of the recess may be 3 times or more the average particle diameter of the heat dissipating particles and less than the average thickness of the heat dissipation coating film structure.

[0019] The heat dissipation coating film structure according to the third aspect is, in the first or second aspect, in the in-plane direction of the heat dissipation coating film structure, there may be a plurality of locations where adjacent particles of the heat dissipating particles are in contact and locations where the distance between adjacent particles is 5 times or more the average particle diameter of the heat dissipating particles.

[0020] The heat dissipation coating film structure according to the fourth aspect is, in any of the first to third aspects, the ratio of the heat dissipating particles to the total weight of the heat dissipating particles and the resin in the heat dissipation coating film structure may be 45.4% by weight or more and 76.9% by weight or less.

[0021] The heat dissipation coating film structure according to the fifth aspect is, in the fourth aspect, the ratio of the heat dissipating particles to the total weight of the heat dissipating particles and the resin in the heat dissipation coating film structure may be 50.0% by weight or more and 66.7% by weight or less.

[0022] In the heat dissipation coating structure according to the sixth embodiment, the resin may be a thermoplastic resin consisting of polyethylene resin, polypropylene resin, or acrylic resin, in any of the first to fifth embodiments described above.

[0023] In the seventh embodiment, the heat dissipation coating structure may be a thermosetting resin consisting of an epoxy resin, an epoxy polyester resin, or a polyester resin, as described in any of the first to fifth embodiments.

[0024] The electronic component according to the eighth embodiment has a heat dissipation coating structure according to any of the first to seventh embodiments formed on its surface.

[0025] The electronic device according to the ninth embodiment has a heat dissipation coating structure according to any of the first to seventh embodiments formed on its surface.

[0026] A method for manufacturing a heat-dissipating coating structure according to the tenth embodiment includes: a compounding process to form composite particles by coating the surface of a powder composed of at least a thermoplastic resin or a thermosetting resin with heat-dissipating particles; a powder layer formation process to form a powder layer by stacking the composite particles; an arrangement process to reduce the voids in the powder layer by pressurizing or heating the powder layer and to form an arrangement layer in which the composite particles are arranged; and a heat curing process to melt the resin by heating the arrangement layer and then cool it to form a heat-dissipating coating structure.

[0027] In the manufacturing method of the heat-dissipating coating structure according to the 11th embodiment, pressurization may be applied during the heat curing step, as in the 10th embodiment.

[0028] The heat dissipation coating structure according to the embodiment of this disclosure will be described in detail below with reference to the attached drawings. In the drawings, substantially identical components are denoted by the same reference numerals.

[0029] (Embodiment 1) Figure 1 shows a cross-sectional view of the cross-sectional structure of a heat-dissipating coating structure according to Embodiment 1. The heat-dissipating coating structure 1 is a planar structure formed on the surface of a substrate 4 and is composed of at least heat-dissipating particles 2 and resin 3. The heat-dissipating particles 2 are particles with an average particle diameter of 0.1 to 30 μm, composed of oxides containing at least two elements selected from aluminum, magnesium, and silicon. The thickness of the heat-dissipating coating structure 1 is 10 times or more the average particle diameter of the heat-dissipating particles 2, and there are multiple recesses 5 on the surface of the heat-dissipating coating structure, with multiple heat-dissipating particles 2 exposed on the surface of the recesses 5. Here, the surface of the recesses 5 refers to the surface that is recessed from the surface of the heat-dissipating coating structure 1, and includes the slope of the recess and the bottom of the recess (area A in the figure).

[0030] With the above configuration, even if a load is applied to the surface of the heat dissipation coating structure 1 due to abrasion or friction, the load is distributed to the numerous heat dissipation particles 2, making them less likely to detach. In addition, the heat dissipation particles 2 located in the recesses 5 are less likely to be physically contacted, making them less prone to wear and thus maintaining heat dissipation performance. Furthermore, the surface area of ​​the heat dissipation coating structure 1 is increased, which also improves heat dissipation performance.

[0031] Next, it is desirable that the depth of the recess 5 be at least three times the average particle diameter of the heat-dissipating particles 2 and less than the average thickness of the heat-dissipating coating structure 1. With this configuration, even if strong external stress such as scratches is applied to the surface of the heat-dissipating coating structure 1 and the heat-dissipating particles 2 present in the shoulder portion of the recess (area B in the figure) detach, the heat-dissipating particles 2 on the surface of the recess 5 are easily maintained because the depth is at least three times the average particle diameter of the heat-dissipating particles 2. Therefore, the effect of maintaining heat dissipation performance and improving durability is obtained.

[0032] Furthermore, it is desirable to have a configuration in the in-plane direction of the heat dissipation coating structure 1 in which there are multiple locations where adjacent heat dissipating particles 2 are in contact, and multiple locations where the distance between adjacent particles is 5 times or more the average particle diameter of the heat dissipating particles 2. This configuration makes it easier to disperse stress due to expansion and contraction caused by temperature changes, as well as stress due to strain, thereby improving the film's durability. Moreover, there will be regions with many heat dissipating particles 2 (indicated by symbol 6 in the figure) and regions with few heat dissipating particles 2 (indicated by symbol 7 in the figure). Therefore, in regions 6 with many heat dissipating particles 2, the heat dissipating particles 2 are more likely to come into contact with each other, which has the effect of improving the thermal conductivity in the thickness direction of the heat dissipation coating structure 1.

[0033] Furthermore, it is desirable that the weight ratio of heat-dissipating particles 2 to the total weight of heat-dissipating particles 2 and resin 3 within the heat-dissipating coating structure 1 be between 45.4% and 71.4% by weight. This is because if the weight ratio of heat-dissipating particles is too high, the film strength will decrease, and if it is too low, the heat dissipation performance will decrease.

[0034] The materials used in this embodiment are described in detail below.

[0035] [Heat dissipating particles 2] <Types of heat-dissipating particles (2)> The far-infrared emissivity on the surface of the heat-dissipating coating structure 1 is affected not only by the heat-dissipating particles 2 that may be present near the surface of the heat-dissipating coating structure 1, but also by the resin 3. Generally, the far-infrared emissivity of resin is between 0.6 and 0.8. Therefore, the far-infrared emissivity of the heat-dissipating particles 2 is greater than that of the resin 3, preferably 0.8 or higher, and more preferably 0.85 or higher. If it is less than 0.8, it may be affected by the far-infrared emissivity of the resin 3, so the far-infrared emissivity of the heat-dissipating coating structure 1 may be less than 0.8, resulting in reduced heat radiation and insufficient heat dissipation performance.

[0036] The objective is to preferably achieve a far-infrared emissivity of 0.85 or higher, more preferably 0.9 or higher, of the heat-dissipating coating structure 1. In this disclosure, the heat-dissipating particles 2 basically use an oxide containing at least two elements selected from the group consisting of aluminum, magnesium, and silicon. By including at least two of these components, the far-infrared emissivity peaks caused by these components can overlap. Therefore, the average value of the far-infrared emissivity in the wavelength range of 2 μm to 22 μm, which contributes to heat transfer in electronic components, can be 0.85 or higher. Preferably, magnesium silicates such as talc or cordierite, magnesium-aluminum carbonates such as hydrotalcite, and aluminosilicates such as zeolite or bentonite are used. Furthermore, the heat-dissipating particles 2 are an oxide containing at least two elements selected from the group consisting of aluminum, magnesium, and silicon, and have a specific surface area of ​​7 m². 2 / g or more 50m 2 These are particles that are less than or equal to / g.

[0037] Here, far-infrared emissivity is the ratio of values ​​between 0 and 1 relative to the ideal state, where the value of blackbody radiation, which is closest to the ideal state, is set to 1.

[0038] <Average particle size of heat-dissipating particles 2> The average particle diameter of the heat-dissipating particles 2 is, for example, in the range of 0.1 μm to 30 μm, preferably in the range of 0.3 μm to 10 μm. The average particle diameter is, for example, the number-average particle diameter of the Ferret diameter (projection width). If the average particle diameter of the heat-dissipating particles 2 is smaller than 0.1 μm, the number of contact points between the heat-dissipating particles 2 in the thickness direction of the heat-dissipating coating structure 1 will increase. As a result, the thermal resistance at the contact point interfaces will increase, impairing thermal conductivity, and consequently, the heat dissipation performance of the heat-dissipating coating structure 1 may decrease. On the other hand, if the average particle diameter of the heat-dissipating particles 2 is larger than 30 μm, the heat-dissipating particles 2 are more likely to detach from the surface of the heat-dissipating coating structure 1 due to wear and friction, and cracking and peeling of the heat-dissipating coating structure 1 may occur, which may decrease the heat dissipation performance of the heat-dissipating coating structure 1.

[0039] <Types of resin 3> Resin 3 is preferably a thermoplastic resin such as polyethylene resin, polypropylene resin, or acrylic resin, or a thermosetting resin such as epoxy resin, epoxy polyester resin, or polyester resin / acrylic resin. Specifically, Resin 3 is preferably a thermoplastic resin that melts upon heating and solidifies upon cooling, or a thermosetting resin that melts upon heating and solidifies as a curing reaction proceeds due to a reaction with a curing agent added to the resin. In other words, it is not particularly limited to any other resin as long as it melts upon heating and solidifies when it is finally cooled.

[0040] <Average particle size of resin 3> The average particle diameter of resin 3 is, for example, in the range of 1 μm to 500 μm, and preferably 5 μm to 300 μm. Furthermore, it is preferably 2 to 50 times the average particle diameter of heat-dissipating particles 2, and preferably 5 to 30 times the average particle diameter of heat-dissipating particles 2. The average particle diameter is, for example, the number-average particle diameter of the Ferret diameter.

[0041] <Method for manufacturing the heat-dissipating coating structure 1> Next, the method for manufacturing the heat-dissipating coating structure 1 in this embodiment will be described with reference to Figure 2. Specifically, the method for manufacturing the heat-dissipating coating structure 1, which consists of at least heat-dissipating particles 2 and resin 3, will be described. It is also possible to add small amounts of pigment or binder (not shown) as needed. Figure 2 is a schematic diagram showing the method for manufacturing the heat-dissipating coating structure 1.

[0042] The manufacturing method for the heat-dissipating coating structure 1 consists of a compounding process (Figure 2(b)) in which heat-dissipating particles 2 and resin 3 (Figure 2(a)) are prepared and compounded to form composite particles 8, a powder layer formation process (Figure 2(c)) in which the composite particles 8 are spread on the surface of a metal structure (substrate) 4 such as aluminum or stainless steel to form a powder layer 9, an arrangement process (Figure 2(d)) in which the composite particles 8 are rearranged by pushing out the gas present in the voids 10 between the composite particles 8 while heating or pressurizing the powder layer 9, and a heat curing process (Figure 2(e)) in which the arrangement layer 11 is further heated or pressurized as necessary to flatten the surface of the arrangement layer 11 while softening the resin 3, and then cured in that state to form the heat-dissipating coating structure 1. The details of each step are explained below.

[0043] [Combination Processing Process] (Figure 2(b)) As preparation for forming the powder layer, it is important to go through a step of dry stirring and mixing of particles consisting of heat-dissipating particles 2 and resin 3. Here, stirring and mixing refers to a method of mixing the heat-dissipating particles 2 and resin 3 while applying compressive and shear forces, but is not particularly limited to any other method. The purpose of this step is to coat at least a portion of the surface of the particles made of resin 3 with heat-dissipating particles 2. By applying compressive and shear forces during mixing, the heat-dissipating particles 2 are partially embedded in the surface of the particles made of resin 3, thereby improving adhesion and obtaining composite particles 8 which are resin 3 particles with heat-dissipating particles 2 coated on the surface.

[0044] Furthermore, the mixing ratio of heat-dissipating particles 2 to resin 3 is, based on weight, for example, 76.9:23.1 to 45.4:54.6, preferably 66.7:33.3 to 50:50. Based on volume, it is 53.6:46.4 to 27.8:72.2, preferably 48.0:52.0 to 31.6:68.4. By keeping the mixing ratio within the above range, a heat-dissipating coating structure 1 with high heat dissipation performance and durability can be obtained.

[0045] [Powder layer formation process] (Figure 2(c)) The following is an example of the powder layer formation process in this embodiment. (1) The composite particles 8, which consist of the heat-dissipating particles 2 and resin 3 obtained in the composite processing step, are dispersed in a solvent in which the heat-dissipating particles 2 and resin 3 do not melt. If necessary, a small amount of inorganic filler or binder such as pigment is dispersed to create a slurry ink, and the obtained ink is applied to the surface of the metal structure 4 and dried to obtain a powder layer 9. Furthermore, while not particularly limited, known coating methods for applying ink include blade coaters, gravure coaters, dip coaters, reverse coaters, roll knife coaters, wire bar coaters, slot die coaters, air knife coaters, curtain coaters, spray coaters, etc., or combinations thereof.

[0046] Examples of solvents used for slurry formation include water and ethanol, but the method is not limited to these. Any solvent that does not chemically react with the heat-dissipating particles 2 and the resin 3 should be appropriately selected. Furthermore, in the drying process, known drying methods or firing methods using heaters, etc., may be employed, without any particular limitations, as long as the solvent can be removed.

[0047] (2) Another method for preparing the powder layer 9 in this embodiment is as follows: A mixed powder is prepared by mixing the compounded particles 8 (not slurryed) in powder form with a small amount of inorganic filler or binder, such as pigment, as needed. This mixed powder is then uniformly deposited on the surface of the metal structure 4 to form a powder layer 9. The method for uniformly depositing the mixed powder is not particularly limited, but known methods include the squeegee method, where the powder is spread with a squeegee; the electrostatic coating method, where the powder is propelled by electrostatic force; the electrostatic screen method; or a combination thereof.

[0048] Here, it is important that when the powder layer 9 is formed, composite particles 8 consisting of resin 3 coated with heat-dissipating particles 2 are deposited, and the heat-dissipating coating structure 1 is manufactured via this process; however, other details are not particularly limited. Hereafter, the method of forming the heat-dissipating coating structure 1 via the formation of this powder layer 9 will be referred to as "dry coating".

[0049] [Alignment Process] (Figure 2(d)) The following are examples of the arrangement process in this embodiment. The surface of the powder layer 9 formed in the powder layer formation process is pressurized and / or heated using a mold or the like, crushing the composite particles 8 and the voids 10 while pushing out the gas (air when working in the atmosphere) present in the voids 10 between the composite particles 8, thereby obtaining an arranged layer 11. For productivity purposes, it is also possible to convey the powder layer 9 while pressurizing it with a pressure roller for roll-to-roll processing.

[0050] [Heat curing process] (Figure 2(e)) The heat curing process in this embodiment may be, for example, the following method. The array layer 11 formed in the array process is pressurized and / or heated using a mold or the like to soften the resin 3, filling the gaps remaining in the array layer 11 with the resin 3 and flattening the surface of the array layer 11. Finally, the resin 3 is solidified by cooling to form the heat dissipation coating structure 1. Considering productivity, it is also possible to transport the array layer 11 while pressurizing it with a pressure roller for roll-to-roll processing. Furthermore, the heating temperature and pressurizing pressure can be set in stages over multiple stages. In addition, it is important to adjust the temperature and pressure so that within the heat dissipation coating structure 1, there are areas 6 where adjacent heat dissipating particles 2 come into contact with each other and areas 7 where they do not come into contact with each other in the in-plane direction (C in the figure), and this can be adjusted appropriately considering the physical properties of the material, the average particle size, etc.

[0051] <Electronic Components> In this embodiment, the electronic component 12 is a component having at least the heat dissipation coating structure 1 described above on its surface, as shown in Figure 3. For example, it is a component used in contact with a metal structure 4 having the heat dissipation coating structure 1 formed on its surface and a heat-generating device 13 (or heating element). It is also possible to omit the metal structure 4 and form the heat dissipation coating structure 1 directly on the surface of the heat-generating device 13. Here, the heat-generating device 13 is not particularly limited as long as it generates heat, but examples include power modules and LED elements.

[0052] <Electronic equipment> In the embodiments of this disclosure, the electronic device 14 is not particularly limited as long as it includes at least the heat dissipation coating structure 1 described above, and examples include smartphones, tablet terminals, lighting equipment, and control units for industrial equipment. For example, Figure 4 shows an electronic device according to an embodiment of the present disclosure, which may consist of a heat dissipation coating structure 1, a heat-generating element 15, a substrate 16, and a tablet housing 17. Thus, the heat dissipation coating structure according to this disclosure can be applied to heat dissipation applications for small, lightweight, and thin electronic devices in which fans or heat sinks cannot be installed.

[0053] The specific details of the embodiments described herein will be explained below with reference to examples, but this disclosure is not limited to the following examples.

[0054] (Examples and Comparative Examples) Detailed information on the heat dissipation coating structures fabricated in the examples and comparative examples is shown in Table 1 of Figure 10. Table 1 in Figure 10 shows the conditions for fabricating the heat-dissipating coating structure in each example and comparative example, including the material types of heat-dissipating particles 2 and resin 3, their mixing ratios (weight %) and volume %), and the manufacturing method. The mixing ratios shown here are the ratios used during manufacturing, but these ratios do not substantially change during the manufacturing process. They represent the mixing ratios within the final heat-dissipating coating structure.

[0055] (Evaluation sample) To evaluate the heat dissipation characteristics of the heat dissipation coating structure, a heat dissipation performance evaluation element 22 was fabricated in the configuration shown in Figure 5, according to the conditions shown in Table 1 of Figure 10, by forming a heat dissipation coating structure 21 with dimensions of 40 mm x 40 mm and a thickness of 0.03 to 0.08 mm on the surface of a 60 mm x 60 mm and 2 mm thick aluminum metal plate 20.

[0056] The specific details of the examples and comparative examples are shown below. Using cordierite particles (average particle size 1.7 μm) (SS-1000: made from round glaze) as heat-dissipating particles, a heat dissipation performance evaluation element 22 including a heat-dissipating coating structure 21 was fabricated according to the coating method described above and the conditions shown in Table 1.

[0057] (Comparative Example 1) In Comparative Example 1, a heat dissipation coating structure 21 was formed on an aluminum metal plate using a conventional wet coating method, and a heat dissipation performance evaluation element 22 was fabricated. Specifically, cordierite particles were dispersed in a solvent containing a resin that can become a silicon resin, such as siloxane, and the mixture was coated and dried onto an aluminum metal plate to form a heat dissipation coating structure 21, which was then used as the heat dissipation performance evaluation element 22.

[0058] (Comparative Example 2) In Comparative Example 2, as shown in Figure 6, the heat dissipation coating structure 21 was not fabricated, and only an aluminum metal plate was used as the heat dissipation performance evaluation element 23.

[0059] (Comparative Examples 3-6 and Examples 1-6) For Comparative Examples 3 to 6 and Examples 1 to 6, a heat dissipation coating structure 21 was formed on an aluminum metal plate using the dry coating method shown in this embodiment, and a heat dissipation performance evaluation element 22 was fabricated.

[0060] Specifically, composite particles were prepared by pre-mixing 5-50 μm particles consisting of cordierite particles and thermoplastic resin (polyethylene: PE) (ACumist B-6: manufactured by Honeywell). A powder layer was formed using the squeegee method, and then an array layer was formed by pressurizing the powder layer with a press machine. Finally, the heat-dissipating coating structure 21 was formed by heating and pressurizing the array layer with a hot press machine. The difference between Comparative Examples 3-6 and Examples 1-6 is that the mixing ratio of the thermoplastic resin to the cordierite particles was increased, thereby changing the blending ratio.

[0061] (Examples 7-16) For Examples 7 to 16, a heat dissipation coating structure 21 was formed on an aluminum metal plate using the manufacturing method shown in this embodiment, and a heat dissipation performance evaluation element 22 was fabricated. Specifically, composite particles were prepared by pre-mixing 5-50 μm particles consisting of cordierite particles and thermosetting resin (epoxy resin: PE) (Perpowder PCE750: manufactured by Pernox). After forming a powder layer of the composite particles using the squeegee method, an array layer was formed by pressurizing the powder layer with a press machine, and a heat dissipation coating structure 21 was formed by heating and pressurizing the array layer with a hot press machine. The difference between Examples 7-16 is that the mixing ratio of the thermosetting resin to the cordierite particles was increased and the blending ratio was changed.

[0062] For the heat dissipation performance evaluation elements 22 fabricated in the comparative examples and examples, far-infrared emissivity and film strength were measured, respectively, to evaluate their thermal radiation and durability. The evaluation methods are as follows.

[0063] <Far-infrared emissivity measurement> The far-infrared emissivity of each sample of the heat dissipation performance evaluation element 22 fabricated in the comparative example and example was measured using a simple emissivity measuring device (product number: TSS-5X, manufactured by Japan Sensor). Here, the far-infrared emissivity is the average value of the spectral far-infrared emissivity in the wavelength range of 2 μm to 22 μm. A far-infrared emissivity of 0.85 or higher was considered to be within the range of practical use, and a range of 0.9 or higher was judged to be even more desirable. Samples with a far-infrared emissivity of 0.85 or lower were evaluated as ×, those between 0.85 and 0.9 as ○, and those above 0.9 as ◎.

[0064] <Membrane strength> For the heat dissipation performance evaluation elements 22 fabricated in the comparative examples and examples, the surface of the heat dissipation coating structure 21 was subjected to a load of 10-20 kgf / cm². 2 The heat dissipation coating structure 21 was rubbed under pressure to check whether the cordierite particles constituting the heat dissipation coating structure 21 would detach. If detachment occurred, the condition was considered impractical; if almost no detachment occurred, it was considered practical; and if no detachment occurred at all, it was considered desirable. Detachment across the entire heat dissipation coating structure was marked with ×, almost no detachment with ○, and no detachment with ◎.

[0065] <Results and Discussion of the Examples> First, we will discuss a comparison between Comparative Example 1, Comparative Examples 3-6, and Examples 1-6. In Comparative Example 1, when manufactured using the conventional wet coating method, the weight ratio of cordierite particles to the total weight of the resin must be very high at 90% in order to ensure far-infrared emissivity. In Comparative Examples 3 and 4, manufactured using the dry coating method described in this embodiment, far-infrared emissivity can be ensured even with a low weight ratio of cordierite particles of 76.9% and 71.4%, but this is insufficient in terms of film strength. On the other hand, in Comparative Examples 5 and 6, manufactured using the dry coating method described in this embodiment, if the weight ratio of cordierite particles is further reduced to 47.6% and 45.4%, film strength can be ensured, but the far-infrared emissivity decreases.

[0066] Next, in Examples 1 to 6, a far-infrared emissivity of 0.85 or higher can be ensured when the weight ratio of cordierite particles is in the range of 66.7 to 50.0%, and film strength can also be ensured. This indicates that, compared to conventional wet coating methods, the ratio of cordierite particles can be reduced by using the dry coating method shown in this embodiment to produce the heat-dissipating coating structure 21. Conversely, it is also possible to maintain the far-infrared emissivity even when the resin ratio is increased.

[0067] Let's discuss the results above. In the manufacturing method of the heat dissipation coating structure 21 by wet coating in Comparative Example 1, the cordierite particles are covered with resin and are less likely to be exposed on the surface of the heat dissipation coating structure 21.

[0068] Furthermore, in Comparative Examples 3 and 4, the weight ratio of cordierite particles is high, while the weight ratio of resin is low, making it difficult to maintain film strength. On the other hand, in Comparative Examples 5 and 6, the weight ratio of cordierite particles is low, while the weight ratio of resin is high, causing the resin to rise to the surface of the heat-dissipating coating structure 21, which hinders the radiation from the surface of the heat-dissipating coating structure 21 and reduces the far-infrared emissivity. In other words, the comparative examples show that it is not possible to achieve both far-infrared emissivity and film strength simultaneously.

[0069] In contrast, as shown in Examples 1 to 6, by depositing composite particles in which cordierite particles are pre-coated on the surface of resin particles, it was possible to expose the cordierite particles on the surface of the heat-dissipating coating structure 21 even with a small amount of cordierite particle content. Furthermore, by decreasing the weight ratio of cordierite particles, it was possible to increase the weight ratio of resin, resulting in stronger film strength and improved durability. Here, the preferred weight ratio of cordierite particles that balances far-infrared emissivity and film strength is 66.7 to 50.0%. More preferably, it is 62.5 to 55.6%.

[0070] Next, we will discuss a comparison between Examples 1-6 and Examples 7-16. It has been confirmed that the range of the weight ratio of cordierite particles that achieves both the far-infrared emissivity and film strength described above can be expanded by changing the resin used to produce the heat-dissipating coating structure 21 from a thermoplastic resin to a thermosetting resin. Specifically, in Examples 1 to 6 using thermoplastic resins, the weight ratio is preferably 66.7 to 50.0%, and more preferably 62.5 to 55.6%, while in Examples 7 to 16 using thermosetting resins, it expands to preferably 76.9 to 45.4%, and more preferably 66.7 to 50.0%.

[0071] The reasons for these results are discussed below. In the process from the arrangement step to the heat curing step for fabricating the heat dissipation coating structure 21, in the case of thermoplastic resins, the viscosity of the resin tends to decrease due to heating, which is thought to be the reason why the following phenomena are likely to occur. If the resin blending ratio is high, the resin tends to rise to the surface of the heat dissipation coating structure 21, hindering the exposure of cordierite particles on the surface of the heat dissipation coating structure 21. If the resin blending ratio is low, the resin tends to aggregate in areas where it flows easily within the heat dissipation coating structure 21, resulting in areas where the cordierite particles and resin do not come into contact, which is thought to reduce the film strength.

[0072] On the other hand, when a thermosetting resin is used in the arrangement process and heat curing process for creating the heat-dissipating coating structure 21, the viscosity of the resin is less likely to decrease due to heating. Also, since curing progresses while heating, when the resin content is high, the phenomenon of the resin rising to the surface of the heat-dissipating coating structure 21 is reduced. Furthermore, when the resin content is low, the pressure applied in the heat curing process makes it easier for the cordierite particles to be pressed into and fixed by the softened resin particles, thus reducing the detachment of the cordierite particles. Therefore, the resin constituting the heat dissipation coating structure 21 is not particularly limited as long as it is a resin that can be heated and pressurized to form a film, but a thermosetting resin is preferred.

[0073] Furthermore, in this embodiment, the surface of the heat-dissipating coating structure 21 has partial depressions, and some of the cordierite particles are exposed on the surface of the depressions. This is thought to increase the surface area of ​​the heat-dissipating coating structure 21 and allow for effective utilization of the radiation performance of the cordierite particles.

[0074] Here, it is preferable that the depth of the recess be at least three times the average particle diameter of the cordierite particles. This ensures that even if the surface of the heat dissipation coating structure wears away and some cordierite particles detach, the shape of the recess can be maintained, and the cordierite particles exposed on the surface of the recess can be retained, thus ensuring heat dissipation performance. Furthermore, it is desirable that the depth of the recess be shallower than the average thickness of the heat dissipation coating structure 21. By making it shallower than the average thickness, the recess penetrates the heat dissipation coating structure 21, preventing a decrease in heat dissipation performance due to the exposure of the surface of the aluminum metal plate 20.

[0075] Next, the actual heat dissipation performance of some of the comparative examples and examples was measured using the following method, and the results are shown in Table 2 of Figure 11.

[0076] <Temperature change measurement to suppress temperature rise> The heat dissipation performance evaluation elements 22 and 23 fabricated in the examples and comparative examples were subjected to temperature rise suppression temperature change measurements using the configuration shown in Figure 7. The specific configuration of the evaluation device is as follows: a heater 24 is attached to the side of the heat dissipation performance evaluation element 22 or 23 where the heat dissipation coating structure is not formed, and an insulating plate 25 is laminated on the opposite side of the heater 24. Furthermore, to avoid the influence of heat conduction due to gaps at the interface, a thermally conductive paste (not shown) was placed between the heat dissipation performance evaluation element 22 or 23 and the heater 24 to create a temperature rise suppression temperature change measuring device 26.

[0077] Next, the temperature rise suppression temperature change measuring device 26 was placed in a constant temperature bath maintained at 25°C, and current was passed through the heater 24 while the temperature was stable and there was no airflow. The voltage was increased, and the difference ΔT between the temperature of the heater 24 measured in Comparative Example 2, which used a heat dissipation performance evaluation element 23 without a heat dissipation coating structure, and the temperature of the heater 24 when using the heat dissipation performance evaluation elements 22 prepared in Comparative Example 1 and Examples 4, 9, and 12 under the same conditions was calculated using the following Equation 1. ΔT = [(Temperature of heater 24 in Comparative Example 2) - (Temperature of heater 24 in Comparative Example 1, Example 4, Example 9, and Example 12)] ... (Equation 1)

[0078] For example, the temperature difference (ΔT) of the heat dissipation performance evaluation element 22 fabricated in Comparative Example 1 was 2.1°C (Figure 11 (Table 2)). Here, the temperature rise suppression rate can be expressed by the following equation 2. Temperature rise suppression rate (%) = ΔT / Temperature of heater 24 in Comparative Example 2 × 100 ... (Equation 2) In this case, a higher temperature rise suppression rate is preferable, and the measured temperature difference (ΔT) and temperature rise suppression rate are shown in Table 2 of Figure 11.

[0079] The temperature rise suppression rates obtained using the above method were 4.0%, 4.9%, and 5.3% in Examples 4, 9, and 12, respectively, compared to 1.7% in Comparative Example 1. The reasons for this are explained below.

[0080] This temperature rise suppression rate is an evaluation result of the overall heat transfer, in which heat emitted from the heater 24 is conducted in the thickness direction of the aluminum metal plate and heat dissipation coating structure 21 that constitute the heat dissipation performance evaluation element 22, and heat is radiated and dissipated from the surface of the heat dissipation coating structure 21.

[0081] Here, we will consider the results for Comparative Example 1 and Examples 4, 9, and 12. As mentioned above, the far-infrared emissivity was similar for all of them, above 0.9, so it is considered that the radiation performance from the surface of the heat-dissipating coating structure 21 is about the same. Therefore, it is thought that the difference is due to the difference in thermal conductivity in the thickness direction of the heat-dissipating coating structure 21. In this example, the heat-dissipating coating structure 21 has a structure in which cordierite particles are in contact with the aluminum metal plate within the heat-dissipating coating structure 21, and furthermore, there are areas where the cordierite particles are closely in contact and areas where they are not. Therefore, it is thought that the areas where the cordierite particles are closely in contact become heat conduction paths, and that this is due to the effect of heat being more easily transferred in the thickness direction of the heat-dissipating coating structure 21.

[0082] In other words, in the conventional wet coating method for manufacturing the heat-dissipating coating structure 21, as in Comparative Example 1, the cordierite particles are dispersed within the heat-dissipating coating structure 21, which is thought to cause resin to be mixed into the contact points between the cordierite particles and between the cordierite particles and the aluminum metal plate, thereby inhibiting heat conduction. In contrast, in the heat-dissipating coating structure 21 manufactured by the dry coating method in this embodiment, it is thought that the aforementioned heat conduction contact points for the cordierite particles are more easily secured.

[0083] Furthermore, the presence of areas within the heat-dissipating coating structure 21 where cordierite particles are closely packed and areas where they are not indicates the presence of scattered areas with a higher concentration of resin. This means that even when the heat-dissipating coating structure 21 is subjected to physical or thermal stress, the scattered resin has the effect of easing the stress, and is expected to prevent cracking and peeling of the heat-dissipating coating structure. As for the structure within the heat-dissipating coating structure, for example, if an arbitrary point is cut in the in-plane direction of the heat-dissipating coating structure, it is desirable that there be areas where adjacent cordierite particles are in contact with each other and areas where the distance between adjacent cordierite particles is five times or more the average particle diameter of the cordierite particles. This distance between adjacent cordierite particles can be controlled by adjusting the average particle diameter of the resin material used when manufacturing the heat-dissipating coating structure and the heating temperature and pressure applied during the manufacturing process of the heat-dissipating coating structure.

[0084] Furthermore, this disclosure includes appropriately combining any embodiment and / or example from the various embodiments and / or examples described above, thereby achieving the effects of each embodiment and / or example. [Industrial applicability]

[0085] The heat-dissipating coating structure described herein offers excellent heat dissipation, reduces the deterioration of heat dissipation performance due to wear and abrasion, and has resistance to stress caused by temperature changes and external loads. [Explanation of Symbols]

[0086] 1 Heat dissipation coating structure 2 Heat dissipating particles 3 Resin 4 Base material (metal structure) 5 recesses 8 Composite particles 9 Powder layer 10 void 11 Array Layers 12 Electronic Components 13 Heating devices 14. Tablet devices (electronic devices) 15 Heating element 16 circuit boards 17 Tablet enclosure 20 Aluminum metal plates 21 Heat dissipation coating structure 22, 23 Heat dissipation performance evaluation elements

Claims

1. A heat-dissipating coating structure is a planar structure composed of at least heat-dissipating particles and resin, The heat-dissipating particles are particles with an average particle diameter of 0.1 to 30 μm, composed of an oxide containing at least two elements selected from aluminum, magnesium, and silicon. The average thickness of the heat-dissipating coating structure is 10 times or more the average particle diameter of the heat-dissipating particles. Multiple recesses exist on the surface of the heat dissipation coating structure, A heat-dissipating coating structure in which multiple heat-dissipating particles are exposed on the surface of the recess.

2. The heat-dissipating coating structure according to claim 1, wherein the depth of the recess is three times or more the average particle diameter of the heat-dissipating particles and less than the average thickness of the heat-dissipating coating structure.

3. The heat-dissipating coating structure according to claim 1 or 2, wherein in the in-plane direction of the heat-dissipating coating structure, there are multiple locations where adjacent heat-dissipating particles are in contact and locations where the distance between adjacent particles is five times or more the average particle diameter of the heat-dissipating particles.

4. The heat-dissipating coating structure according to any one of claims 1 to 3, wherein the ratio of the heat-dissipating particles to the total weight of the heat-dissipating particles and the resin within the heat-dissipating coating structure is 45.4% by weight or more and 76.9% by weight or less.

5. The heat-dissipating coating structure according to claim 4, wherein the ratio of the heat-dissipating particles to the total weight of the heat-dissipating particles and the resin within the heat-dissipating coating structure is 50.0% by weight or more and 66.7% by weight or less.

6. The heat dissipation coating structure according to any one of claims 1 to 5, wherein the resin is a thermoplastic resin consisting of polyethylene resin, polypropylene resin, or acrylic resin.

7. The heat dissipation coating structure according to any one of claims 1 to 5, wherein the resin is a thermosetting resin consisting of an epoxy resin, an epoxy polyester resin, a polyester resin, or an acrylic resin.

8. An electronic component having a heat dissipation coating structure according to any one of claims 1 to 7 formed on its surface.

9. An electronic device having a heat dissipation coating structure according to any one of claims 1 to 7 formed on its surface.

10. A compounding process in which a composite particle is formed by coating the surface of a powder composed of a thermosetting resin with heat-dissipating particles, A powder layer formation step in which the composite particles are stacked to form a powder layer, The process includes an arrangement step in which the powder layer is pressurized or heated to reduce the voids in the powder layer, thereby forming an arrangement layer in which the composite particles are arranged, A heat curing step is performed in which the resin is melted by heating the aforementioned array layer and then cooled to form a heat dissipation coating structure. including, A method for manufacturing a heat dissipation coating structure according to claim 1.

11. A method for manufacturing a heat-dissipating coating structure according to claim 10, characterized by applying pressure during the heat curing step.

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