Heat dissipation coating structure, electronic component using the heat dissipation coating structure, electronic device

Abstract

To provide a heat dissipation coating structure superior in heat dissipation and having durability.SOLUTION: The heat dissipation coating structure is a heat dissipation coating structure that has heat-dissipating particles and resin. The heat-dissipating particles are composed of oxides containing at least two elements selected from the group consisting of aluminum, magnesium and silicon, and with a particle size of 0.1 to 30 μm. The average thickness of the heat dissipation coating structure is more than 10 times the average particle diameter of the heat dissipating particles, the heat dissipation coating structure has a space sealed from the outside. The maximum length of the space is more than 5 times the average particle diameter of heat-dissipating particles, and in an area of 30% or more of the interface that forms the space, heat-dissipating particles protrude into the space.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a heat-dissipating coating film structure capable of dissipating heat from a heating element to the outside through thermal radiation, as well as to an electronic member and an electronic device including the heat-dissipating coating film structure.

Background Art

[0002] In recent years, with the miniaturization and higher density of power devices and semiconductor packages, the heat generation density of devices has increased. For this reason, for electronic members mounted in devices, technology for efficiently dissipating heat generated from each electronic member has become essential so as not to exceed the guaranteed operating temperature.

[0003] As heat dissipation means, fins utilizing convection, heat conductive sheets utilizing heat conduction, and the like are generally used. However, as heat dissipation means, it is difficult to dissipate heat to below the guaranteed operating temperature of heating elements such as heat-generating devices included in devices only with such conventional heat countermeasure members. In recent years, heat-dissipating paints and heat-dissipating coating films using thermal radiation, as well as sheets and members having a heat-dissipating coating film formed on their surfaces, have attracted attention as means capable of dissipating heat without securing extra space.

[0004] Figure 8 is a cross-sectional view of a planar structure (hereinafter referred to as "heat-dissipating coating structure 33") fabricated on a substrate 31 by a conventional method, such as that described in Patent Document 1. As shown in Figure 8, the heat-dissipating coating structure 33 is composed of a resin 30 and heat transfer particles 32. Heat from the substrate 31 is transferred in the thickness direction within the heat-dissipating coating structure 33 mainly by the heat transfer particles 32 present within the heat-dissipating coating structure 33, and then dissipated from the surface of the heat-dissipating coating structure 33. When forming this heat-dissipating coating structure 33, an ink composed of the resin 30, heat transfer particles 32, and a solvent to dissolve the resin is created, and the ink is coated and dried to produce a heat-dissipating coating structure 33 containing a certain amount of heat transfer particles 32 with a large particle size (hereinafter this manufacturing process will be referred to as "wet coating"). Furthermore, the disclosure states that irregularities caused by the large particle size heat transfer particles 32 are formed on the surface of the heat-dissipating coating structure 33, increasing the surface area and improving heat dissipation performance. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2009 / 142036 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the manufacturing method of the heat dissipation coating structure 33 described in Patent Document 1 presents the following problems, particularly in the central part of the heat dissipation coating structure 33. Due to thermal expansion and contraction of the heat dissipation coating structure 33, cracks and delamination are likely to occur at the interface with the substrate 31 (A in the figure) or at the interface with the heat transfer particles and the resin (B in the figure). This is because the thermal expansion coefficients of the resin 30 and the heat transfer particles 32 are different, so for example, cracks occur at the interface between the heat transfer particles 32 and the resin 30 due to expansion and contraction, and these cracks propagate, causing delamination and cracks at the interface between the heat dissipation coating structure 33 and the substrate 31, or inside the heat dissipation coating structure 33.

[0007] 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]

[0008] To achieve the above objective, the heat dissipation coating structure according to this disclosure is a heat dissipation coating structure having 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 the group consisting of 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, the heat dissipation coating structure has a space sealed from the outside, the maximum length of the space is 5 times or more the average particle diameter of the heat dissipating particles, and the heat dissipating particles protrude into the space over an area of ​​30% or more of the interface forming the space. [Effects of the Invention]

[0009] The heat dissipation coating structure according to this disclosure can be obtained that has excellent heat dissipation properties and resistance to cracking and peeling due to thermal expansion and contraction. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view showing the cross-sectional structure of the heat dissipation coating structure according to Embodiment 1. [Figure 2] (a) to (e) are schematic cross-sectional views showing each step of the manufacturing method for the heat dissipation coating structure according to Embodiment 1. [Figure 3] This is a schematic cross-sectional view showing the cross-sectional structure of an electronic component according to Embodiment 1. [Figure 4] This is a schematic perspective view showing the structure of the electronic device according to Embodiment 1. [Figure 5] This is a schematic cross-sectional view showing the cross-sectional structure of the evaluation element in the comparative example and the example. [Figure 6] (a) to (c) are cross-sectional views showing the state of the composite particles when the heat dissipation coating structure is formed in the embodiment. [Figure 7](a) is a cross-sectional view showing the cross-sectional structure of the heat dissipation coating structure in the embodiment, and (b) is an enlarged cross-sectional view of the area around the space in (a). [Figure 8] This is a schematic cross-sectional view showing the cross-sectional structure of the heat dissipation coating structure described in Patent Document 1. [Figure 9] (a) is a schematic cross-sectional view showing the cross-sectional structure of a heat dissipation coating structure having an internal space according to a reference example, and (b) is an enlarged cross-sectional view of the periphery including the internal space of (a). [Figure 10] Table 1 shows the detailed contents of the heat dissipation coating structures prepared in the examples and comparative examples, including the mixing ratio, manufacturing conditions such as stirring and mixing, and evaluation results. [Modes for carrying out the invention]

[0011] (Background leading to this disclosure) The inventors investigated a method to intentionally incorporate air bubbles (hereinafter referred to as "spaces") inside a heat dissipation coating structure 43 and to disperse expansion and contraction stresses through these spaces. A schematic diagram of a reference example of a heat dissipation coating structure 43 having a space 44 created by intentionally incorporating air bubbles during the wet coating process described above is shown in Figure 9(a). An enlarged cross-sectional view of the area including the space 44 is also shown in Figure 9(b). In this case, the interface (inner surface) between the space 44 and the heat dissipation coating structure is... In this structure, the resin 40 is raised on the surface. The inventors have found that, in the heat dissipation coating structure according to the reference example, a problem occurs in which cracks form in the resin 40 (C in the figure) on the surface of the space 44 due to expansion and contraction stress.

[0012] As a result of diligent research, the present inventors have found that a heat-dissipating coating structure having heat-dissipating particles and a thermosetting resin has a space inside that is sealed from the outside, and the heat-dissipating particles protrude into the space over an area of ​​30% or more of the interface forming the space, thereby obtaining the heat-dissipating coating structure according to the present disclosure. By adopting the above configuration, stress caused by thermal expansion and contraction is alleviated in the heat dissipation coating structure, resulting in a reduced likelihood of peeling or cracking of the heat dissipation coating structure.

[0013] A heat dissipation coating film structure according to a first aspect is a heat dissipation coating film structure comprising heat-dissipating particles and a resin, wherein the heat-dissipating particles are particles with an average particle diameter of 0.1 to 30 µm that are formed of an oxide containing at least two elements selected from the group consisting of aluminum, magnesium, and silicon, the average thickness of the heat dissipation coating film structure is at least 10 times the average particle diameter of the heat-dissipating particles, the heat dissipation coating film structure has an externally sealed space inside, the maximum length of the space is at least 5 times the average particle diameter of the heat-dissipating particles, and the heat-dissipating particles protrude into the space in 30% or more of the area of the interface forming the space.

[0014] A heat dissipation coating film structure according to a second aspect, in the above-described first aspect, may be configured such that a height at which the heat-dissipating particles protruding toward the space side on the interface protrude into the space from the interface is 0.05 µm or more and 15 µm or less.

[0015] A heat dissipation coating film structure according to a third aspect, in the above-described first aspect, may be configured such that inside the heat dissipation coating film structure, the heat-dissipating particles have a structure of being connected in a mesh shape in the resin, and a part of the mesh-shaped heat-dissipating particles is in contact with the interface of the space.

[0016] An electronic member according to a fourth aspect comprises: an electronic member having a heating element; and the heat dissipation coating film structure according to any one of the first to third aspects described above, the heat dissipation coating film structure being disposed in direct or indirect contact with the heating element.

[0017] An electronic device according to a fifth aspect comprises: an electronic device having a heating element; and the heat dissipation coating film structure according to any one of the first to third aspects described above, the heat dissipation coating film structure being disposed in direct or indirect contact with the heating element.

[0018] A method for manufacturing a heat-dissipating coating structure according to the sixth aspect is a method for manufacturing a heat-dissipating coating structure having heat-dissipating particles and a resin, comprising: a compounding process to form composite particles in which heat-dissipating particles are coated on the surface of resin particles made of resin; a film forming process to form a powder film by stacking the composite particles; and a thermosetting process to heat the powder film and harden it while melting the resin, wherein the compounding process uses resin particles from at least two groups with different average particle sizes.

[0019] The heat dissipation coating structure according to the embodiment will be described in more detail below with reference to the drawings.

[0020] (Embodiment 1) First, the heat dissipation coating structure according to Embodiment 1 will be described in detail with reference to Figure 1. Figure 1 is a schematic cross-sectional view showing the cross-sectional structure of the heat dissipation coating structure according to Embodiment 1. For convenience, the thickness direction is defined as the Z direction, and the right side of the paper is defined as the X direction. The heat-dissipating coating structure 1 according to Embodiment 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. The heat-dissipating coating structure has a space 5 that is sealed from the outside, the maximum length of the space 5 is 5 times or more the average particle diameter of the heat-dissipating particles, and the heat-dissipating particles 2 protrude into the space 5 over an area of ​​30% or more of the interface (inner surface) forming the space 5.

[0021] By adopting the above configuration, the heat dissipation coating structure 1 is made less susceptible to stress caused by thermal expansion and contraction, resulting in reduced likelihood of peeling or cracking of the heat dissipation coating structure 1.

[0022] The materials used in the heat dissipation coating structure according to this embodiment 1 will be described in detail below.

[0023] [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 the resin 3 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.

[0024] The objective is to make the far-infrared emissivity of the heat-dissipating coating structure 1 preferably 0.85 or higher, more preferably 0.9 or higher. Therefore, 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 containing at least two of these components of aluminum, magnesium, and silicon, the peaks of far-infrared emissivity caused by these components can overlap. As a result, 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, it is desirable to use magnesium silicates such as talc or cordierite, magnesium-aluminum carbonates such as hydrotalcite, or aluminosilicates such as zeolite or bentonite. Furthermore, an oxide containing at least two elements selected from the group consisting of aluminum, magnesium, and silicon, with a specific surface area of ​​7 m² is also desirable. 2 / g or more 50m 2 The particles may be less than or equal to / g.

[0025] 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.

[0026] <Particle size of heat-dissipating particle 2> The average particle diameter of the heat-dissipating particles 2 is, for example, within the range of 0.1 μm to 30 μm, preferably within the range of 0.3 μm to 10 μm. If the 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, which may reduce the heat dissipation performance of the heat-dissipating coating structure 1. On the other hand, if the particle diameter of the heat-dissipating particles 2 is larger than 30 μm, the heat-dissipating particles 2 may 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 reduce the heat dissipation performance of the heat-dissipating coating structure 1.

[0027] <Types of resin 3> Resin 3 is preferably a resin that melts when heated and solidifies when finally cooled. For example, it is preferably a thermoplastic resin such as polyethylene or polypropylene, or a thermosetting resin such as epoxy resin, epoxy polyester resin, polyester resin, or acrylic resin. Furthermore, if the heat resistance of the finished heat-dissipating coating structure is required, it must be one of the above thermosetting resins.

[0028] <Particle size of 3 resin particles> Resin 3 used particles composed of Resin 3 as a raw material (hereinafter referred to as "Resin 3 particles"). The particle sizes used were divided into three groups: one with an average particle size of 4 to 10 μm, one with an average particle size of 20 to 35 μm, and one with an average particle size of 50 to 100 μm. Furthermore, it is desirable to use a mixture of resin particles from at least two groups with different average particle sizes. The reason for this will be explained later. The average particle size refers to the volume-average particle size.

[0029] <Method for manufacturing the heat-dissipating coating structure 1> Next, the method for manufacturing the heat-dissipating coating structure 1 according to Embodiment 1 will be described with reference to Figure 2. Specifically, the method for manufacturing the heat-dissipating coating structure 1, which is composed 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 cross-sectional view showing each step of the method for manufacturing the heat-dissipating coating structure 1 according to Embodiment 1.

[0030] The method for manufacturing the heat dissipation coating structure 1 includes the following steps. (1) Prepare the heat-dissipating particles 2 and the resin 3 (Figure 2(a)). (2) A composite particle 8 is formed by combining each of the components (composite processing step (Figure 2(b))). (3) 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 (powder layer formation process (Figure 2(c))). (4) The powder layer 9 is heated and / or pressurized to push out the gas present in the space 10 between the composite particles 8, rearranging the composite particles 8 and forming the arrangement layer 11 (arrangement step (Figure 2(d))). (5) Furthermore, the array layer 11 is heated or pressurized as necessary to soften the resin 3 and flatten the surface of the array layer 11, and then hardened in that state to form the heat dissipation coating structure 1 (heat curing process (Figure 2(e))). Through the above steps, a heat dissipation coating structure 1 can be obtained.

[0031] In the composite processing step (Figure 2(b)), it is desirable to use resin 3 particles from at least two different groups with varying average particle sizes. This is because using resin 3 particles with different average particle sizes from two or more groups allows for the formation of spaces 10 of a predetermined size in the powder layer 9 during the subsequent powder layer formation step (Figure 2(c)). More specifically, while numerous spaces (hereinafter referred to as small spaces) exist between the composite particles 8 within the powder layer 9, using resin 3 particles with larger particle sizes allows for the intentional creation of larger spaces (hereinafter referred to as large spaces) compared to the small spaces. By creating these large spaces, a portion of the space resulting from the large spaces remains within the heat-dissipating coating structure 1 during the subsequent arrangement step (Figure 2(d)) and heat-curing step (Figure 2(e)), forming a heat-dissipating coating structure 1 with spaces 5. Adjusting the temperature and pressure conditions during the arrangement step (Figure 2(d)) and heat-curing step (Figure 2(e)) is also effective in forming the heat-dissipating coating structure shown in this embodiment.

[0032] The details of each step are explained below.

[0033] [Compounding 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 resin 3 particles, improving adhesion and resulting in composite particles 8, which are resin 3 particles with heat-dissipating particles 2 coated on the surface. Here, as mentioned above, it is important to use resin materials for the resin 3 particles that have average particle sizes from at least two or more different groups.

[0034] For example, let's consider a case using three resin particles from two different groups with varying average particle sizes. We'll describe an example of a mixing procedure, using the resin with the smaller average particle size as the first resin particle and the resin with the larger average particle size as the second resin particle. (a) First, the first resin particles and the heat-dissipating particles 2 are stirred and mixed to produce the first composite particles. (b) Next, the second resin particles and the heat-dissipating particles 2 are stirred and mixed to create the second composite particles. (c) Subsequently, the first composite particle and the second composite particle were mixed to form composite particle 8.

[0035] Here, the mixing procedure is not limited to the one described above, and it is also possible to stir-mix the first resin particles, the second resin particles, and the heat-dissipating particles 2 together. However, the objective is to form a state in which the heat-dissipating particles are immobilized or coated on at least a portion of the surfaces of the first resin and the second resin, and the procedure is not particularly limited to the extent that this objective is achieved.

[0036] Similarly, when using three resin particles from three different groups with varying average particle sizes, we will describe an example of a mixing procedure, using the resin with the smallest average particle size as the first resin, the resin with the largest average particle size as the second resin, and the resin with an even larger average particle size as the third resin particle. (a) First, the first resin particles and the heat-dissipating particles 2 are stirred and mixed to produce the first composite particles. (b) Next, the second resin particles and the heat-dissipating particles 2 are stirred and mixed to create the second composite particles. (c) Furthermore, the third resin particles and the heat-dissipating particles 2 are stirred and mixed to create a third composite particle. (d) Subsequently, the first composite particle, the second composite particle, and the third composite particle were mixed to form composite particle 8.

[0037] Furthermore, the mixing ratio of the total heat-dissipating particles 2 to the total resin 3 is, based on weight, for example, 76.9:23.1~45.4:54.6, preferably 66.7:33.3~50:50. Also, based on volume, it is 53.6:46.4~27.8:72.2, preferably 48.0:52.0~31.6:68.4. By keeping the mixing ratio within the above range, a heat-dissipating coating structure 1 with high heat dissipation performance and high durability can be obtained. Here, the total resin 3 refers to the sum of the first and second resin particles when using resin 3 particles from two groups with different average particle sizes as described above. When using resin 3 particles from three groups with different average particle sizes, it refers to the sum of the first, second, and third resin particles.

[0038] [Powder layer formation process] (Figure 2(c)) The powder layer formation process in this embodiment may be, for example, the following method. (1) Composite particles 8, which consist of 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 dissolve. 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 a metal structure (substrate) 4 and dried to obtain a powder layer 9.

[0039] Furthermore, the method of applying the ink is not particularly limited, but examples of known application methods 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.

[0040] Examples of solvents used for slurry formation include water and ethanol, but are not limited to these. Any solvent that does not dissolve the heat-dissipating particles 2 and resin 3 and does not cause a chemical reaction should be appropriately selected. Furthermore, any known drying method using a heater or other means, or a firing method, may be used for drying, as long as the solvent can be removed.

[0041] (2) Another method for preparing the powder layer 9 in this embodiment 1 is as follows: A mixed powder is prepared by mixing the powdered composite particles 8 (not slurryed) with a small amount of inorganic filler or binder, such as pigment, as needed. This mixed powder is uniformly deposited on the surface of the metal structure (substrate) 4 to form a powder layer 9. The method for uniformly depositing the mixed powder is not particularly limited, but examples of 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.

[0042] Here, it is important that when the powder layer 9 is formed, the heat-dissipating coating structure 1 is manufactured by depositing composite particles 8, which consist of resin 3 coated with heat-dissipating particles 2 on their surface; however, other details are not particularly limited. Hereafter, the method of forming the heat-dissipating coating structure 1 through the formation of this powder layer 9 will be referred to as "dry coating".

[0043] [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, and the composite particles 8 and a portion of the spaces 10 (the small spaces and large spaces mentioned above) present in the spaces between the composite particles 8 are pushed out, crushing the composite particles 8 and a portion of the spaces 10 to obtain the 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.

[0044] [Heat curing process] (Figure 2(e)) The heat curing process in this embodiment 1 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 spaces 10 remaining within 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-dissipating coating structure 1. Considering productivity, it is also possible to convey the powder layer 9 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 steps. What is important here is that, of the small and large spaces that make up the above space 10, the small spaces are filled with softened resin 3, and the large spaces are filled with resin 3, but a portion of it remains as space inside the heat dissipation coating structure 1.

[0045] The heat dissipation coating structure described in this embodiment 1 can be applied to, for example, the following electronic materials and electronic devices.

[0046] <Electronic Components> In Embodiment 1, the electronic component 16 is a component having at least the heat dissipation coating structure 1 described above on its surface, as shown in the schematic cross-sectional view of Figure 3. For example, a metal structure (substrate) 4 with the heat dissipation coating structure 1 formed on its surface is used in contact with a heating 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 heating 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.

[0047] <Electronic equipment> In Embodiment 1, the electronic device 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 is a schematic perspective view showing an electronic device 18 according to Embodiment 1, which may consist of a heat dissipation coating structure 1, a heating element 15, a substrate 4, and a tablet housing 17. Thus, this disclosure can be applied to heat dissipation applications for small, lightweight, and thin electronic devices where fans or heat sinks cannot be installed.

[0048] Next, the specific details of the embodiments in this disclosure will be explained below with reference to examples, but this disclosure is not limited to the following examples.

[0049] (Examples and Comparative Examples) Detailed information regarding the mixing ratio, manufacturing conditions such as stirring and mixing, and evaluation results of the heat dissipation coating structure 1 prepared in the examples and comparative examples is shown in Table 1 of Figure 10.

[0050] (Evaluation sample) To evaluate the film durability of the heat dissipation coating structure 1, an evaluation element 22 was fabricated by forming a heat dissipation coating structure 21 measuring 40 mm x 40 mm and 0.03 to 0.08 mm in thickness on the surface of a 60 mm x 60 mm, 2 mm thick aluminum metal plate 20, according to the conditions shown in Table 1 of Figure 10 and the configuration shown in Figure 5.

[0051] The specific details of the examples and comparative examples are shown below. Composite particles were created using cordierite particles (average particle size 1.7 μm) (SS-1000: manufactured by Marusu Yuyaku) as heat-dissipating particles and resin particles consisting of thermosetting resin (epoxy resin: PE) (Perpowder PCE750: manufactured by Pernox) as the resin. An evaluation element 22 including a heat-dissipating coating structure 21 was fabricated according to the manufacturing method described above and the conditions shown in Table 1 of Figure 10. Here, the resin particles made of thermosetting resin were pre-crushed / classified using a sieve or similar method, and three groups of resin particles were used: particles with an average particle diameter of 8 μm, particles with an average particle diameter of 24 μm, and particles with an average particle diameter of 63 μm. Below, these resin particles were used according to the conditions of each comparative example and example to produce composite particles 8. The conditions for producing composite particles 8 will be explained using Table 1 in Figure 10. Here, in Table 1 in Figure 10, the above resin particles are shown as particle I for particles with an average particle diameter of 8 μm, particle II for particles with an average particle diameter of 24 μm, and particle III for particles with an average particle diameter of 63 μm, and below in the detailed explanation, they will be referred to as particles I to III.

[0052] (Comparative Example 1) For Comparative Example 1, a heat dissipation coating structure 21 was formed on an aluminum metal plate 20 using the manufacturing method shown in this embodiment, and an evaluation element 22 was fabricated. Here, the mixing ratio of cordierite particles to three resin particles was set to 66.7:33.3 by weight and 48.0-52.0 by volume. The resin used was particle II, and the film thickness was adjusted to 30-50 μm to fabricate the heat dissipation coating structure 21.

[0053] (Comparative Example 2) Next, evaluation element 22 was fabricated using the same method as in Comparative Example 1. The only difference was that the mixing ratio of cordierite particles to resin particles was 50.0:50.0 by weight and 31.6-68.4 by volume, while all other conditions were the same.

[0054] (Comparative Examples 3-4) Next, evaluation elements 22 were fabricated for Comparative Examples 3 and 4 using the same method as for Comparative Examples 1 and 2. The mixing ratio of cordierite particles to resin particles was the same as that used for Comparative Examples 1 and 2, and was applied to Comparative Examples 3 and 4. The difference from Comparative Examples 1 and 2 was that the resin particles used consisted of particle I and particle II. The ratio of particle I to particle II was 10.0:90.0 by weight, and the weight percentage of particle II was 90 wt%. Since the same material resin particles were used here, the volume ratio was also the same as the weight ratio. All other conditions were the same as for Comparative Examples 1 and 2.

[0055] (Examples 1 and 2) For Examples 1 and 2, evaluation elements 22 were fabricated using the same procedure as in Comparative Examples 1 and 2. The mixing ratio of cordierite particles to resin particles was the same as that used in Comparative Examples 1 and 2. The difference from Comparative Examples 1 and 2 is that particle II and particle III were used as the composition of the resin particles. The ratio of particle II to particle III was 90.0:10.0 by weight, and the weight percentage of particle III was 90 wt%. Here, since the same material resin particles were used, the volume ratio is the same as the weight ratio. Other conditions were the same as in Comparative Examples 1 and 2.

[0056] (Examples 3 and 4) For Examples 3 and 4, evaluation elements 22 were fabricated in the same manner as in Comparative Examples 1 and 2. The mixing ratio of cordierite particles to resin particles was the same as that used in Comparative Examples 1 and 2 for Examples 3 and 4. The difference from Comparative Examples 1 and 2 is that the resin particles used consisted of particles I and particles II. The ratio of particles I to particles II was 10.0:90.0 by weight, and the weight percentage of particles II was 90 wt%. Here, since the same material, the resin particles, was used, the volume ratio was also the same as the weight ratio. In addition, as a difference in the mixing method, particles II and a predetermined amount of cordierite particles were first stirred and mixed (indicated as stirring and mixing (1) in Table 1), then particles I and a predetermined amount of cordierite particles were stirred and mixed (indicated as stirring and mixing (2) in Table 1), and finally the materials from stirring and mixing (1) and (2) were mixed to make composite particles 8. Furthermore, the total amount of cordierite particles and resin particles used in stirring and mixing (1) and stirring and mixing (2) were adjusted to match the aforementioned ratio of cordierite particles to resin particles, and the amount of cordierite particles used in stirring and mixing (1) and stirring and mixing (2) was distributed in proportion to the amount of resin particles used in stirring and mixing (1) and stirring and mixing (2). All other conditions remained the same.

[0057] (Comparative Example 5.6) In Comparative Examples 5 and 6, the evaluation element 22 was fabricated using the same method as in Examples 3 and 4. The mixing ratio of cordierite particles to resin particles was the same as that used in Examples 3 and 4 for Comparative Examples 5 and 6. The only difference from Examples 3 and 4 was that the thickness of the heat dissipation coating structure was set to 60-80 μm. All other conditions were the same.

[0058] (Examples 5, 6) In Examples 5 and 6, evaluation elements 22 were fabricated using the same method as in Comparative Examples 5 and 6. The mixing ratio of cordierite particles to resin particles was the same as that used in Examples 3 and 4. The difference from Comparative Examples 3 and 4 is that particle III material was used instead of particle I in the composition of the resin particles used. The ratio of particle II to particle III was 90.0:10.0 by weight, and the weight percentage of particle III was 10.0 wt%. Here, since the same resin particles were used, the volume ratio was the same as the weight ratio. The mixing method involved first stirring and mixing particle II with a predetermined amount of cordierite particles (indicated as stirring and mixing (1) in Table 1), then stirring and mixing particle III with a predetermined amount of cordierite particles (indicated as stirring and mixing (2) in Table 1), and finally mixing the materials from stirring and mixing (1) and (2) to produce composite particle 8. Furthermore, the total amount of cordierite particles and resin particles used in stirring and mixing (1) and stirring and mixing (2) were adjusted to match the aforementioned ratio of cordierite particles to resin particles, and the amount of cordierite particles used in stirring and mixing (1) and stirring and mixing (2) was distributed in proportion to the amount of resin particles used in stirring and mixing (1) and stirring and mixing (2). All other conditions remained the same.

[0059] (Comparative Examples 7, 8) In Comparative Examples 7 and 8, the evaluation element 22 was fabricated using the same method as in Examples 5 and 6. The mixing ratio of cordierite particles to resin particles was the same as that used in Examples 5 and 6 for Comparative Examples 7 and 8. The only difference from Examples 5 and 6 was that the thickness of the heat dissipation coating structure was set to 90-110 μm. All other conditions were the same.

[0060] (Examples 7, 8) In Examples 7 and 8, the evaluation element 22 was fabricated in the same manner as in Comparative Examples 7 and 8. The mixing ratio of cordierite particles to resin particles was the same as that used in Comparative Examples 7 and 8. The difference from Comparative Examples 7 and 8 is that the resin particles used consisted of particles I, II, and III. The ratio of particles I to II to III was 10.0:80.0:10.0 by weight. Since the same material, the resin particles, was used here, the volume ratio is the same as the weight ratio. The mixing method involved first stirring and mixing particles II and a predetermined amount of cordierite particles (indicated as stirring and mixing (1) in Table 1), then stirring and mixing particles I and a predetermined amount of cordierite particles (indicated as stirring and mixing (2) in Table 1), then stirring and mixing particles III and a predetermined amount of cordierite particles (indicated as stirring and mixing (3) in Table 1), and finally mixing the materials from stirring and mixing (1), (2), and (3) to produce composite particle 8. Furthermore, the total amount of cordierite particles and resin particles used in stirring and mixing (1), stirring and mixing (2), and stirring and mixing (3) were adjusted to match the aforementioned ratio of cordierite particles to resin particles, and the amount of cordierite particles used in stirring and mixing (1), stirring and mixing (2), and stirring and mixing (3) was distributed in proportion to the amount of resin particles used in stirring and mixing (1), stirring and mixing (2), and stirring and mixing (3). All other conditions remained the same.

[0061] <Membrane durability evaluation> The evaluation elements 22 prepared in the comparative example and the example were heated to 150°C, then placed on a metal block at 25°C and rapidly cooled. This process was repeated 10 times to check the deterioration state of the heat dissipation coating structure, and the results are shown in Table 1 of Figure 10. The evaluation criteria are as follows.

[0062] The central part of the heat dissipation coating structure was checked for cracks or delamination. If no cracks were found, it was marked with ○; if minute cracks were found but the heat dissipation coating structure did not break, it was marked with △; and if cracks large enough to break the heat dissipation coating structure or delamination of the heat dissipation coating structure was found, it was marked with ×.

[0063] <Results and Discussion of the Examples> First, in Comparative Examples 1 and 2, it was confirmed that the heat-dissipating coating structure peeled off from the aluminum metal plate from the central part. On the other hand, in Comparative Examples 3 and 4, although it was confirmed that using resin particles with a small average particle size of 8 μm, such as particle I, reduced the occurrence of cracks, some minute cracks remained, indicating that it was not sufficient.

[0064] On the other hand, as shown in Examples 1 and 2, by using large resin particles with an average particle diameter of 63 μm, such as particle III, an effect of improving crack resistance was obtained.

[0065] Next, we will compare Comparative Examples 3 and 4 with Examples 3 and 4. As shown in Examples 3 and 4, the procedure for forming the composite particle 8 involved pre-mixing particle II and particle I with predetermined amounts of cordierite particles, which was found to suppress the cracks observed in Comparative Examples 3 and 4. Furthermore, in Examples 3 and 4, it was confirmed that spaces with a maximum length of 9 to 20 μm existed within the heat-dissipating coating structure. It is believed that the presence of these spaces helps to disperse or alleviate the stress generated by thermal expansion and contraction.

[0066] The behavior by which this space is formed is considered as follows. Figure 6 shows the powder state of composite particles 8, consisting of 3 resin particles and 2 heat-dissipating particles (cordierite particles), before the formation of the heat-dissipating coating structure, and the state after the resin particles have melted and bonded together after the formation of the heat-dissipating coating structure. Figure 6(a) shows the state of Comparative Examples 1 and 2, Figure 6(b) shows the state of Examples 1 and 2, and Figure 6(c) shows the state of Examples 3 and 4. In Figure 6(a) of Comparative Examples 1 and 2, before the formation of the heat-dissipating coating structure, composite particles 8, consisting of resin 3 particles with heat-dissipating particles 2 covering at least a portion of their surface, exist with spaces 10. Subsequently, when forming the heat-dissipating coating structure, heating and pressurizing melt and deform the resin 3 forming the composite particles 8, pushing out the gas present in the spaces 10, causing the spaces 10 to disappear. This is because the composite particle 8 exists as composite particle 25 with uniform particle size. On the other hand, in Examples 1 and 2 of Figure 6(b), since the composite particles 8 contain composite particles 26 with a large particle size, when forming the heat dissipation coating structure, the composite particles 26 act as pillars, making it difficult for air bubbles present in the space 10 to escape. This is thought to be because it was possible to form a space 5 inside the heat dissipation coating structure that originates from the space 10.

[0067] Furthermore, in Examples 3 and 4 of Figure 6(c), smaller composite particles 27 are present among the composite particles 8. Therefore, when forming the heat-dissipating coating structure, the composite particles 27 tend to come into contact with other composite particles at multiple points. This is thought to have hindered the effect of other composite particles melting and pushing out the gas present in space 10, thus facilitating the formation of space 5 within the heat-dissipating coating structure due to space 10. Furthermore, in Comparative Examples 3 and 4, since particle I was pre-mixed with particle II before being stirred and mixed with heat-dissipating particle 2, particle I adhered to the surface of particle II, and then heat-dissipating particle 2 coated it. As a result, the effect shown in Figure 6(c) was not obtained, and the result was closer to Figure 6(a), which is why the crack-suppressing effect was considered weak.

[0068] Next, Comparative Examples 5 and 6 will be described. Compared to Examples 3 and 4, it is thought that the increased film thickness of the heat dissipation coating structure made it easier for stress to occur in the film. On the other hand, cracks are reduced by mixing in particle III, which is a resin particle with a larger average particle size, as in Examples 5 and 6. This is thought to be due to the effect described in Figure 6(c).

[0069] Furthermore, compared to Examples 5 and 6, increasing the film thickness of the heat-dissipating coating structure in Comparative Examples 7 and 8 resulted in crack formation. This is also thought to be due to increased stress caused by the further increase in film thickness. However, as shown in Examples 7 and 8, the combined use of resin particles with a large average particle size (particle III) and resin particles with a small average particle size (particle I) was found to suppress crack formation. This is thought to be because the effects shown in Figures 6(b) and 6(c) worked together to actively form space 5 inside the heat-dissipating coating structure.

[0070] Furthermore, the space 5 within the heat dissipation coating structure will be explained using Figure 7. Figure 7(a) shows a cross-section of the heat dissipation coating structure fabricated in this embodiment. Figure 7(b) is an enlarged view of the area surrounding the space 5 within the heat dissipation coating structure. The effect of suppressing cracks in the above embodiment is thought to be due to the dispersion or relaxation of stress caused by the presence of space 5 within the heat dissipation coating structure. Here, space 5 exists in a shape that has been stretched by the pressure applied when forming the heat dissipation coating structure 1, such as a spherical, ellipsoidal, or elongated shape. The maximum length of space 5 within the heat dissipation coating structure 1 fabricated in this embodiment was 9 to 30 μm. As a result of careful consideration, it is preferable that the maximum length of this space 5 is at least 5 times the average particle diameter of the heat dissipating particles 2 and less than or equal to the film thickness of the heat dissipation coating structure 1. Furthermore, it is desirable that it be at least 5 times the average particle diameter of the heat dissipating particles 2 and less than or equal to half the film thickness of the heat dissipation coating structure 1. If it is less than 5 times, the above-mentioned effect is difficult to obtain, and the crack suppression effect is weak. Furthermore, if the space is too large, the strength of the heat dissipation coating structure 1 will weaken, raising concerns about reduced durability against wear. Here, the maximum length of space 5 refers to the maximum straight-line distance of the interface forming space 5 in a cross-section when space 5 within the heat dissipation coating structure 1 is cut by an arbitrary plane.

[0071] Furthermore, at the interface forming space 5, it is desirable that the area exposed within space 5 by the heat-dissipating particles 2 from the resin 3 is 30% or more of the interface area. If the heat-dissipating particles 2 were present at the interface in a close-packed manner, the theoretical area occupied by the heat-dissipating particles 2 would be approximately 90% of the total interface area. Therefore, it is desirable that at least one-third of the interface is exposed to the heat-dissipating particles. If it is less than 30%, the effect of suppressing cracks at the interface of space 5, as described in Figure 8(c), will be diminished.

[0072] Furthermore, in terms of heat conduction in the thickness direction within the heat-dissipating coating structure, the presence of space 5 has the disadvantage of reducing heat transfer efficiency around space 5. However, the presence of many heat-dissipating particles 2 at the interface of space 5 facilitates the formation of heat conduction paths via the heat-dissipating particles 2, thus compensating for the above disadvantage. Therefore, it is desirable for the area occupied by heat-dissipating particles 2 at the interface of space 5 to be large. For this reason, it is desirable for the area occupied by heat-dissipating particles 2 at the interface to be between 30% and 90%.

[0073] Furthermore, at the interface of space 5, the maximum height to which the heat-dissipating particles protrude into space 5 (X in Figure 7(b)) should preferably be less than or equal to half the average particle diameter of the heat-dissipating particles 2. In other words, since the average particle diameter of the heat-dissipating particles is 0.1 to 30 μm, half of that, or 0.05 to 15 μm, is desirable. If more than half of the particle protrudes, detachment of the heat-dissipating particles 2 from the interface of space 5 may occur, which could lead to crack formation at the detached locations.

[0074] Furthermore, in order to effectively form the heat conduction paths described above, it is preferable that the heat-dissipating particles are connected in a mesh-like manner in the thickness direction of the heat-dissipating coating structure. When forming the composite particles 8 described in this embodiment, it is easy to form the mesh structure of these heat-dissipating particles 2 by fixing or coating the surface of the resin particles 3 in advance.

[0075] Furthermore, the effects described in this embodiment are similar when the mixing ratio of cordierite particles to the three resin particles is in the range of 66.7:33.3 to 50.0:50.0 by weight and 48.0 to 52.0 to 31.6 to 68.4 by volume, and are effective at least within this range.

[0076] Furthermore, this disclosure includes appropriately combining any of the various embodiments and / or examples described above, and the effects of each embodiment and / or example can be achieved. [Industrial applicability]

[0077] The heat dissipation coating structure according to this disclosure can provide a member having the heat dissipation coating structure on its surface. Furthermore, it can provide an electronic member including such a member, and an electronic device including such an electronic member. [Explanation of Symbols]

[0078] 1 Heat dissipation coating structure 2 Heat dissipating particles 3 Resin 4 Base material (metal structure) 5 Space 8, 25, 26, 27 Composite particles 9 Powder layer 10 Space 11 Array Layers 15 Heating element 16 Electronic Components 17 Tablet enclosure 18 Electronic equipment 20 Aluminum metal plates 21 Heat dissipation coating structure 22 Evaluation

Claims

1. A heat-dissipating coating structure having 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 the group consisting of 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. The heat dissipation coating structure has a space that is sealed from the outside, The maximum length of the aforementioned space is five times or more the average particle diameter of the heat-dissipating particles. In an area of ​​30% or more of the interface forming the space, the heat-dissipating particles protrude into the space. Heat dissipation coating structure.

2. The heat-dissipating coating structure according to claim 1, wherein the height of the heat-dissipating particles protruding into the space from the interface is 0.05 μm or more and 15 μm or less.

3. The heat dissipation coating structure according to claim 1, wherein the heat dissipation coating structure has a structure in which the heat dissipating particles are arranged in a mesh-like manner within the resin, and a portion of the mesh-like heat dissipating particles is in contact with the interface of the space.

4. An electronic component having a heating element, The heat dissipation coating structure according to any one of claims 1 to 3, which is arranged in direct or indirect contact with the heating element, Electronic components, including those mentioned above.

5. Electronic equipment having a heating element, The heat dissipation coating structure according to any one of claims 1 to 3, which is arranged in direct or indirect contact with the heating element, Electronic devices, including those mentioned above.

6. A method for manufacturing a heat-dissipating coating structure having heat-dissipating particles and resin, A compounding process is performed to form composite particles in which the heat-dissipating particles are coated on the surface of resin particles composed of the aforementioned resin. A film formation step in which a powder film is formed by stacking the aforementioned composite particles, A heat curing step in which the powder film is heated and the resin is heated and cured, Includes, The composite treatment step is a method for manufacturing a heat dissipation coating structure, using resin particles from at least two groups with different average particle sizes.

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