JP2023108811A - Heat-dissipating coating structure and electronic member and electronic device using the structure - Google Patents

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 The present disclosure relates to a heat-dissipating coating structure capable of dissipating the heat of a heating element to the outside by thermal radiation, and to an electronic member and an electronic device including the heat-dissipating coating structure.

In recent years, as power devices and semiconductor packages have become smaller and denser, the heat generation density of equipment has increased. Therefore, it is essential to develop a technique for efficiently dissipating the heat generated from each electronic member so that the temperature of the electronic member mounted in the device does not exceed the guaranteed operating temperature.

As the heat dissipation means, fins using convection, heat conductive sheets using heat conduction, and the like are generally used. However, it is difficult to radiate heat below the guaranteed operating temperature of a heating element such as a heating device included in the equipment only with such a conventional heat countermeasure member as a heat radiation means. In recent years, as a means for dissipating heat without securing a space, attention has been focused on heat-radiating coatings and heat-radiating coating films that utilize thermal radiation, and sheets and members having heat-radiating coating films formed on their surfaces.

FIG. 8 shows a cross-sectional structure of a planar structure (hereinafter referred to as “heat-dissipating coating film structure 33”) fabricated on a substrate 31 by the conventional method described in Patent Document 1, for example. It is a sectional view showing. As shown in FIG. 8 , the heat-dissipating coating structure 33 is composed of a resin 30 and heat-transfer particles 32 , and the heat from the substrate 31 is mainly transferred to the heat-transfer particles existing in the heat-dissipating coating structure 33 . 32 conducts heat in the heat-dissipating coating structure 33 in the thickness direction, and radiates heat from the surface of the heat-dissipating coating structure 33 . At this time, a certain amount of heat-transfer particles 32 having a large particle size are contained in the heat-dissipating coating structure 33 to form irregularities on the surface of the heat-dissipating coating structure 33, thereby increasing the surface area and improving the heat dissipation performance. It is the content that makes

Also, FIG. 9 is a cross-sectional view showing a cross-sectional structure of a heat-dissipating coating film structure 35 produced on a substrate 31 by the conventional method described in Patent Document 2, for example. An outermost layer 34 containing radioactive particles 36 is formed on the outermost surface of the particle-containing film. Here, by including radioactive particles 36 having a particle diameter larger than the thickness of the outermost layer 34, part of the radioactive particles 36 are exposed from the outermost layer 34, and radiation from the surface of the radioactive particles 36 is increased. It is intended to promote the removal of heat transferred from the base material 31 and improve the heat radiation performance.

WO2009-142036 JP 2006-281514 A

In the manufacturing method of the heat-dissipating coating film structure 33 of Patent Document 1, the heat-transfer particles 32 are mixed with the resin 30 or the resin component which is the raw material of the resin 30, and the solvent for dissolving the resin component, and the base material 31 is formed. It is a method of drying and curing after coating on the surface (this manufacturing method is hereinafter referred to as "wet coating").

However, in this method, a film of the resin 30 is formed on the outermost surface of the heat-dissipating coating structure 33, and the heat transfer performance in the thickness direction near the surface of the heat-dissipating coating structure 33 and the radiation performance from the surface deteriorate. In addition, the resin 30 enters between the adjacent heat transfer particles 32, and the heat transfer property in the heat-dissipating coating film structure 33 is lowered. Further, in order to secure the heat transfer property in the heat-dissipating coating film structure 33 and arrange the heat-transfer particles 32 in the vicinity of the surface of the heat-dissipating coating film structure 33 to improve the radiation, it is possible to contain a large amount of the heat-transfer particles 32 . is necessary. As a result, the content of the resin component is reduced, and expansion and contraction due to temperature changes and external stress applied to the heat dissipation coating structure 33 may cause cracks in the heat dissipation coating structure 33 and separation from the base material 31 . .

In Patent Document 2, since the radioactive particles 36 protrude from the outermost surface layer 34 of the heat-dissipating coating structure 35, the radioactive particles 36 are likely to detach due to abrasion or rubbing, and the durability of the heat-dissipating coating structure is reduced. There's a problem.

Accordingly, an object of the present disclosure is to provide a heat-dissipating coating structure having excellent heat dissipation and durability.

In order to achieve the above object, a heat-dissipating coating structure according to the present disclosure is a heat-dissipating coating structure that is a planar structure composed of at least heat-dissipating particles and a resin, wherein 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 equal to that of the heat-dissipating particles. It is 10 times or more the average particle diameter, a plurality of recesses are present on the surface of the heat-dissipating coating structure, and a plurality of heat-dissipating particles are exposed on the surfaces of the recesses.

Further, an electronic member according to the present disclosure has the heat-dissipating coating film structure formed on its surface.

Further, the electronic device according to the present disclosure has the heat-dissipating coating film structure formed on its surface.

Further, the method for manufacturing a heat-dissipating coated film structure according to the present disclosure includes a compounding process for forming composite particles in which the surface of powder composed of at least a thermoplastic resin or a thermosetting resin is coated with heat-dissipating particles. a powder layer forming step of forming a powder layer in which the composite particles are laminated; and an arrangement in which the powder layer is pressurized or heated to reduce the voids in the powder layer and the composite particles are arranged. It includes an aligning step of forming a layer, and a heat curing step of heating the aligning layer to melt the resin once and cooling it to form a heat-dissipating coating film structure.

The heat-dissipating coating structure according to the present disclosure is a heat-dissipating coating structure that has excellent heat dissipation properties, reduces deterioration in heat dissipation performance due to wear and friction, and has resistance to stress caused by temperature changes and external loads. can be obtained.

1 is a cross-sectional view showing a cross-sectional structure of a heat-dissipating coating film structure according to Embodiment 1; FIG. It is sectional drawing which shows the manufacturing method of the heat dissipation coating film structure in embodiment. It is a sectional view showing a section structure of an electronic member in an embodiment. It is a figure which shows the cross-section of the electronic device in embodiment. FIG. 5 is a cross-sectional view showing a cross-sectional structure of a heat dissipation performance evaluation element in Comparative Example 1 and Examples 1 to 20; 6 is a cross-sectional view showing a cross-sectional structure of a heat dissipation performance evaluation element in Comparative Example 2. FIG. It is a sectional view showing composition of a temperature rise control temperature change evaluation device. FIG. 2 is a cross-sectional view showing a cross-sectional structure of a heat-dissipating coating film structure in Patent Document 1; FIG. 3 is a cross-sectional view showing a cross-sectional structure of a heat-dissipating coating film structure in Patent Document 2; 1 is Table 1 showing the details of heat-dissipating coating film structures produced in Examples and Comparative Examples. Fig. 2 is Table 2 showing the actual effect of heat dissipation performance for some of Comparative Examples and Examples.

A heat-dissipating coating structure according to a first aspect is a heat-dissipating coating structure that is a planar structure composed of at least heat-dissipating particles and a resin, wherein the heat-dissipating particles are aluminum, magnesium, and silicon. Particles with an average particle diameter of 0.1 to 30 μm composed of an oxide containing at least two elements selected from As described above, there are a plurality of recesses on the surface of the heat-dissipating coating structure, and a plurality of heat-dissipating particles are exposed on the surfaces of the recesses.

A heat-dissipating coating film structure according to a second aspect is the first aspect, wherein the depth of the recess is at least three times the average particle diameter of the heat-dissipating particles and less than the average thickness of the heat-dissipating coating structure. good too.

A heat-dissipating coating film structure according to a third aspect is a heat-dissipating coating film structure according to the first or second aspect, in which the adjacent particles of the heat-dissipating particles are in contact with each other in the in-plane direction of the heat-dissipating coating structure. There may be a plurality of locations where the distance between the matching particles is five times or more the average particle diameter of the heat-dissipating particles.

A heat-dissipating coating structure according to a fourth aspect is, in any one of the first to third aspects, a ratio of the heat-dissipating particles to the total weight of the heat-dissipating particles and the resin in the heat-dissipating coating structure may be 45.4% by weight or more and 76.9% by weight or less.

A heat-dissipating coating film structure according to a fifth aspect is the fourth aspect, wherein the ratio of the heat-dissipating particles to the total weight of the heat-dissipating particles and the resin in the heat-dissipating coating structure is 50.0% by weight or more and 66 0.7% by weight or less.

In the heat-dissipating coating film structure according to a sixth aspect, in any one of the first to fifth aspects, the resin may be a thermoplastic resin such as polyethylene resin, polypropylene resin, or acrylic resin.

A heat-dissipating coating film structure according to a seventh aspect is characterized in that, in any one of the first to fifth aspects, the resin may be an epoxy resin, an epoxy polyester resin, or a thermosetting resin made of a polyester resin. good.

An electronic member according to an eighth aspect has the heat-dissipating coating structure according to any one of the first to seventh aspects formed on its surface.

An electronic device according to a ninth aspect has the heat-dissipating coating structure according to any one of the first to seventh aspects formed on its surface.

A method for manufacturing a heat-dissipating coated film structure according to a tenth aspect includes a compositing process 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; and an arrangement in which the powder layer is pressurized or heated to reduce the voids in the powder layer and the composite particles are arranged. It includes an aligning step of forming a layer, and a heat curing step of heating the aligning layer to melt the resin once and cooling it to form a heat-dissipating coating film structure.

In the method for manufacturing a heat-dissipating coating film structure according to the eleventh aspect, in the tenth aspect, pressure may be applied in the heat curing step.

Hereinafter, a heat-dissipating coating film structure according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the same code|symbol is attached|subjected about the substantially same member in drawing.

(Embodiment 1)
FIG. 1 shows a cross-sectional view showing a cross-sectional structure of a heat-dissipating coating film structure according to Embodiment 1. FIG. The heat-dissipating coating film structure 1 is a planar structure formed on the surface of the substrate 4 and is composed of at least heat-dissipating particles 2 and a resin 3 . The heat-dissipating particles 2 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 thickness of the heat-dissipating coating structure 1 is is 10 times or more the average particle diameter of the heat-dissipating particles 2 , a plurality of recesses 5 exist on the surface of the heat-dissipating coating structure, and a plurality of heat-dissipating particles 2 are exposed on the surfaces of the recesses 5 . Here, the surface of the recess 5 indicates a surface that is recessed from the surface of the heat-dissipating coating film structure 1, and indicates a portion (region A in the drawing) that includes the slope of the recess and the bottom of the recess. there is

With the above configuration, even if a load is applied to the surface of the heat-dissipating coating film structure 1 due to abrasion or rubbing, the load is distributed to a large number of the heat-dissipating particles 2, making it difficult for the heat-dissipating particles 2 to come off. In addition, since the heat-dissipating particles 2 present in the concave portions 5 are difficult to come into physical contact with each other, the heat-dissipating particles 2 are less likely to be worn, and the heat-dissipating performance can be easily maintained. Furthermore, the surface area of the heat-dissipating coating film structure 1 is increased, and there is also the effect of improving the heat-dissipating performance.

Next, it is desirable that the depth of the concave portions 5 is three times or more the average particle diameter of the heat-dissipating particles 2 and less than the average thickness of the heat-dissipating coating film structure 1 . With this configuration, even if a strong external stress such as a scratch 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 concave portion (region B in the figure) detach, , the heat-dissipating particles 2 are easily maintained on the surface of the recesses 5 because the depth is three times or more the average particle diameter of the heat-dissipating particles 2 . Therefore, the effect of maintaining the heat radiation performance and improving the durability can be obtained.

Further, in the in-plane direction of the heat-dissipating coating film structure 1, the distance between the portion where the adjacent particles of the heat-dissipating particles 2 are in contact with each other and the distance between the adjacent particles is at least five times the average particle diameter of the heat-dissipating particles 2. It is desirable to have a configuration in which there are multiple locations. With this configuration, the stress due to expansion and contraction due to temperature change and the stress due to strain can be easily dispersed, and the film resistance is improved. Furthermore, there are regions (reference numeral 6 in the drawing) and regions (reference numeral 7 in the drawing) in which there are few heat dissipating particles 2 . Therefore, the heat-dissipating particles 2 are likely to come into contact with each other in the region 6 where there are many heat-dissipating particles 2 , which has the effect of improving the thermal conductivity in the thickness direction of the heat-dissipating coating film structure 1 .

Further, it is desirable that the weight ratio of the heat-dissipating particles 2 to the total weight of the heat-dissipating particles 2 and the resin 3 in the heat-dissipating coating structure 1 is 45.4% by weight or more and 71.4% by weight or less. This is because if the weight ratio of the heat-dissipating particles is too high, the film strength is lowered, and if it is too low, the heat-dissipating performance is lowered.

Details of the materials used in this embodiment will be described below.

[Heat-dissipating particles 2]
<Types of heat-dissipating particles 2>
The far-infrared emissivity of the surface of the heat-dissipating coating structure 1 is affected not only by the heat-dissipating particles 2 that may exist near the surface of the heat-dissipating coating structure 1 but also by the resin 3 . In general, the far-infrared emissivity of resin is 0.6 or more and 0.8 or less. Therefore, the far-infrared emissivity of the heat-dissipating particles 2 is larger than that of the resin 3, preferably 0.8 or more, and more preferably 0.85 or more. 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 smaller than 0.8, and the heat Emissivity decreases and heat dissipation performance becomes insufficient.

For the purpose of making the far-infrared emissivity of the heat-dissipating coating structure 1 preferably 0.85 or more, more preferably 0.9 or more, in the present disclosure, the heat-dissipating particles 2 are basically aluminum, An oxide containing at least two elements selected from the group consisting of magnesium and silicon is used. By including at least two components out of aluminum, magnesium and silicon, the far-infrared emissivity peaks resulting from these components can overlap. Therefore, the average value of far-infrared emissivity in the wavelength range of 2 μm to 22 μm, which contributes to heat transfer of electronic members, can be 0.85 or more.
Preferably, magnesium silicates such as talc and cordierite, magnesium-aluminum carbonates such as hydrotalcite, and aluminosilicates such as zeolite and bentonite are used.
Furthermore, the heat-dissipating particles 2 are oxides containing at least two elements selected from the group consisting of aluminum, magnesium, and silicon, and have a specific surface area of 7 m ² /g or more and 50 m ² /g or less. be.

Here, the far-infrared emissivity is a ratio representing a value within the range of 0 to 1 with respect to this ideal state, where 1 is the value of black body radiation that is closest to the ideal state.

<Average particle diameter of heat-dissipating particles 2>
The average particle size of the heat dissipating particles 2 is, for example, within the range of 0.1 μm or more and 30 μm or less, preferably within the range of 0.3 μm or more and 10 μm or less. The average particle size is, for example, the number average particle size of the Feret diameter (projected width). When the average particle size 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 increases. As a result, the heat transfer resistance at the interface between the contact points increases, the heat conductivity is impaired, and as a result, the heat dissipation performance of the heat dissipation coating structure 1 may be reduced. On the other hand, when the average particle diameter of the heat-dissipating particles 2 is larger than 30 μm, the heat-dissipating particles 2 detach from the surface of the heat-dissipating coating structure 1 due to abrasion or rubbing, or the heat-dissipating coating structure 1 cracks or peels off. It is likely to occur, and the heat dissipation performance of the heat-dissipating coating film structure 1 may be lowered.

<Type of Resin 3>
The 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, polyester resin, or acrylic resin. Specifically, this resin 3 is a thermoplastic resin that is once melted by heating and solidified by cooling, or a thermosetting resin that is melted once by heating and solidified by the reaction of a curing agent added inside the resin. A flexible resin is desirable. That is, there is no particular limitation as long as it is a resin that melts when heated and then solidifies when finally cooled.

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

<Method for producing heat-dissipating coating film structure 1>
Next, a method for manufacturing the heat-dissipating coating film structure 1 according to the present embodiment will be described with reference to FIG. Specifically, a method for manufacturing the heat-dissipating coating film structure 1 composed of at least the heat-dissipating particles 2 and the resin 3 will be described. A small amount of pigment or binder (not shown) can be added as needed. FIG. 2 is a schematic diagram showing a method for manufacturing the heat-dissipating coating film structure 1. FIG.

The method for manufacturing the heat-dissipating coating film structure 1 includes a compounding treatment step (see FIG. 2 (b) of (b)), and a powder layer forming step ((c )), and an arranging step ( FIG. 2 ( d)), and further heating or, if necessary, pressurizing the alignment layer 11 to soften the resin 3 while flattening the surface of the alignment layer 11, and curing in this state to form the heat-dissipating coating film structure 1. It consists of a heat curing step (FIG. 2(e)).
Details of each step are described below.

[Composite treatment step] ((b) in FIG. 2)
As a preliminary preparation for forming the powder layer, it is important to pass through a step of dry-stirring and mixing the particles composed of the heat-dissipating particles 2 and the resin 3 . Here, "stirring and mixing" means a method of mixing while applying compressive force and shear force when mixing the heat dissipating particles 2 and the resin 3, and is not particularly limited thereto. The purpose of this step is to coat the heat-dissipating particles 2 on at least part of the surface of the particles made of the resin 3 . By applying a compressive force and a shearing force during mixing, the heat-dissipating particles 2 are partially embedded in the surface of the particles made of the resin 3 to improve adhesion, and the surface is coated with the heat-dissipating particles 2. Composite particles 8 which are resin 3 particles are obtained.

The compounding ratio of the heat-dissipating particles 2 and the resin 3 is, on a weight basis, 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 to 27.8:72.2, preferably 48.0:52.0 to 31.6:68.4. By setting the compounding ratio within the above range, it is possible to finally obtain the heat-dissipating coating film structure 1 having high heat-dissipating performance and high durability.

[Powder layer forming step] ((c) in FIG. 2)
As the powder layer forming step in the present embodiment, for example, there are the following methods.
(1) The composite particles 8 composed of the heat-dissipating particles 2 and the resin 3 obtained in the composite treatment step are dispersed in a solvent in which the heat-dissipating particles 2 and the resin 3 do not melt, and if necessary, a small amount is dispersed. A powder layer 9 is obtained by dispersing an inorganic filler such as a pigment and a binder to prepare a slurry ink, applying the obtained ink to the surface of the metal structure 4 and drying it.
In addition, the method of applying the ink is not particularly limited, but blade coater, gravure coater, dip coater, reverse coater, roll knife coater, wire bar coater, slot die coater, air knife coater, curtain coater, spray coater, or the like, or Known application methods for these combinations can be mentioned.

Solvents used for slurrying include, for example, water and ethanol, but are not limited to these, and a solvent that does not chemically react with the heat-dissipating particles 2 and the resin 3 may be appropriately selected.
Moreover, in drying, there is no particular limitation as long as the solvent can be removed, and a known drying method using a heater or the like or a baking method may be employed.

(2) Another method for forming the powder layer 9 in this embodiment is the following method.
Composite particles 8 in a powder state (not slurried) are mixed with a small amount of an inorganic filler such as a pigment or a binder, if necessary, to prepare a mixed powder. The obtained mixed powder is uniformly deposited on the surface of the metal structure 4 to form the powder layer 9 . The method for uniformly depositing the mixed powder is not particularly limited, but a squeegee method that spreads the powder with a squeegee, an electrostatic coating method that uses an electrostatic force to make the powder fly, and an electrostatic screen. method, or a combination thereof.

Here, when the powder layer 9 is formed, it is important to manufacture the heat-dissipating coating film structure 1 through the form in which the composite particles 8 made of the resin 3 coated with the heat-dissipating particles 2 are deposited. However, other contents are not particularly limited. Hereinafter, the method of forming the heat-dissipating coating film structure 1 through the formation of the powder layer 9 will be referred to as "dry coating".

[Arrangement step] ((d) in FIG. 2)
Examples of the arranging step in the present embodiment include the following methods.
The surface of the powder layer 9 formed in the powder layer forming step is pressurized and/or heated using a mold or the like, and the gas present in the gaps 10 existing between the composite particles 8 (in the atmosphere Composite particles 8 and voids 10 are crushed while extruding air (in the case of operation 1) to obtain alignment layer 11 . In consideration of productivity, it is also possible to convey the powder layer 9 while applying pressure with a pressure roller for roll-to-roll processing.

[Heat curing step] ((e) in FIG. 2)
As the heat curing step in the present embodiment, for example, there are the following methods.
The alignment layer 11 formed in the alignment step is pressurized and/or heated using a mold or the like to soften the resin 3 and fill the gaps remaining in the alignment layer 11 with the resin 3 . Flatten the surface. By finally cooling, the resin 3 is solidified to form the heat-dissipating coating film structure 1 . When productivity is taken into consideration here, it is also possible to convey the orientation layer 11 while applying pressure with a pressure roller for roll-to-roll processing. Also, the heating temperature and the pressurizing pressure can be set stepwise for a plurality of times. Further, the temperature and pressure are adjusted so as to form a portion 6 where the adjacent heat dissipating particles 2 are in contact with each other and a portion 7 where the adjacent heat dissipating particles 2 are not in contact with each other in the in-plane direction (C in the figure) in the heat dissipating coating structure 1. Therefore, it is possible to appropriately adjust the particle size in consideration of the physical properties of the material, the average particle size, and the like.

<Electronic materials>
In the embodiment, the electronic member 12 is a member having at least the above-described heat-dissipating coating film structure 1 on its surface, as shown in FIG. For example, it is a member used in contact with a metal structure 4 having a heat-dissipating coating film structure 1 formed thereon and a heating device 13 (or heating element). It is also possible to omit the metal structure 4 and directly form the heat dissipation coating film structure 1 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, and examples thereof include power modules and LED elements.

<Electronic equipment>
In the embodiment of the present disclosure, the electronic device 14 is not particularly limited as long as it includes at least the heat-dissipating coating structure 1 described above. etc.
For example, FIG. 4 shows an electronic device according to an embodiment of the present disclosure, which can be composed of a heat-dissipating coating structure 1 , a heating element 15 , a substrate 16 and a tablet housing 17 .
Thus, the heat-dissipating coating structure according to the present disclosure can be applied to heat-dissipating small, lightweight, and thin electronic devices in which a fan or heat sink cannot be installed.

Hereinafter, the specific contents of the embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to the following examples.

(Examples and Comparative Examples)
Table 1 in FIG. 10 shows the details of the heat-dissipating coating film structures produced in Examples and Comparative Examples.
In Table 1 of FIG. 10, the conditions for producing the heat-dissipating coating structure in each example and comparative example are the material types of the heat-dissipating particles 2 and the resin 3, the compounding ratio (% by weight and volume%), and the manufacturing method. about
The compounding ratio shown here is the mixing ratio at the time of manufacturing, but this compounding ratio does not substantially change during the manufacturing process, and indicates the mixing ratio in the finally formed heat-dissipating coating structure. be.

(Evaluation sample)
In evaluating the heat dissipation characteristics of the heat dissipation coating structure, according to the conditions shown in Table 1 of FIG. 10, with the configuration shown in FIG. A heat dissipation performance evaluation element 22 having a heat dissipation coating film structure 21 with a thickness of up to 0.08 mm was produced.

Specific contents in Examples and Comparative Examples are shown below.
Using cordierite particles (average particle diameter 1.7 μm) (SS-1000: manufactured by Marusu Yaze) as heat dissipating particles, according to the coating method described above and the conditions shown in Table 1, heat dissipating including the heat dissipating coating film structure 21 A performance evaluation element 22 was produced.

(Comparative example 1)
For Comparative Example 1, a conventional wet coating method was used to form a heat-dissipating coating film structure 21 on an aluminum metal plate to produce a heat-dissipating performance evaluation element 22 . Specifically, cordierite particles are dispersed in a solvent in which a resin that can be a silicone resin such as siloxane is dissolved, coated on an aluminum metal plate and dried to form a heat dissipation coating film structure 21, and a heat dissipation performance evaluation element 22 is formed. and

(Comparative example 2)
As for Comparative Example 2, as shown in FIG.

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

Specifically, cordierite particles and thermoplastic resin (polyethylene: PE) (ACumistB-6: manufactured by Honeywell) particles of 5 to 50 μm are mixed in advance to prepare composite particles, and the composite particles are processed using a squeegee method. After forming the powder layer, the powder layer was pressed with a press to form an alignment layer, and the heat-dissipating coating film structure 21 was formed by heating and pressurizing the alignment layer with a hot press. . The difference between Comparative Examples 3 to 6 and Examples 1 to 6 is that the mixing ratio of the thermoplastic resin to the cordierite particles was increased to change the compounding ratio.

(Examples 7-16)
For Examples 7 to 16, a heat dissipation performance evaluation element 22 was prepared by forming a heat dissipation coating film structure 21 on an aluminum metal plate using the preparation method shown in this embodiment.
Specifically, cordierite particles and thermosetting resin (epoxy resin: PE) (Pelpowder PCE750: manufactured by Pelnox) particles of 5 to 50 μm are mixed in advance to prepare composite particles, and are combined using a squeegee method. After forming a powder layer of particles, a pressing machine is used to press the powder layer to form an alignment layer, and a heat press is used to heat and press the alignment layer to form the heat-dissipating coating film structure 21 . formed. The difference between Examples 7 to 16 is that the blending ratio was changed by increasing the mixing ratio of the thermosetting resin to the cordierite particles.

Far-infrared emissivity and film strength were measured in order to evaluate thermal radiation and durability of the heat dissipation performance evaluation elements 22 produced in the comparative example and the example, respectively. Each evaluation method is as follows.

<Far-infrared emissivity measurement>
The far-infrared emissivity of each sample was measured using a simplified emissivity measuring device (product number: TSS-5X, manufactured by Japan Sensor) for the heat dissipation performance evaluation elements 22 produced in Comparative Examples and Examples. Here, the far-infrared emissivity is a value obtained by averaging the spectral far-infrared emissivity in the wavelength range of 2 μm to 22 μm. Here, far-infrared emissivity of 0.85 or more is regarded as a practical range, and a more desirable range is 0.9 or more. Those of 85 to 0.9 were evaluated as ◯, and those of 0.9 or more were evaluated as ⊚.

<Film strength>
For the heat dissipation performance evaluation element 22 produced in Comparative Examples and Examples, the surface of the heat dissipation coating film structure 21 was rubbed with a pressure of 10 to 20 kgf/cm ² to remove the cordierite particles constituting the heat dissipation coating structure 21. was confirmed to be detached. Here, the state of detachment is of low practicality, the state of almost no detachment is judged to be practical, and the state of no detachment is judged to be a desirable state, and detachment occurs over the entire surface of the heat-dissipating coating structure. A sample was evaluated as x, a sample that hardly desorbed was rated as ◯, and a sample that did not desorb was rated as ⊚.

<Results and Discussion of Examples>
First, comparisons of Comparative Example 1, Comparative Examples 3 to 6, and Examples 1 to 6 will be described.
When the conventional wet coating method of Comparative Example 1 was used, the blending weight ratio of the cordierite particles to the total weight of the cordierite particles and the resin was as high as 90% in order to secure the far-infrared emissivity. need to be higher. In addition, in the case of Comparative Examples 3 and 4 manufactured using the dry coating method described in the present embodiment, even if the blending weight ratio of the cordierite particles is as low as 76.9% and 71.4%, Infrared emissivity can be ensured, but the film strength is insufficient. On the other hand, in Comparative Examples 5 and 6, which were manufactured using the dry coating method described in the present embodiment, when the blending weight ratio of the cordierite particles was further lowered to 47.6% and 45.4%, the film strength was secured. It can be done, but the far-infrared emissivity decreases.

Next, in Examples 1 to 6, a far-infrared emissivity of 0.85 or more can be ensured and film strength can be ensured when the blending weight ratio of the cordierite particles is in the range of 66.7 to 50.0%. This means that the compounding ratio of the cordierite particles can be reduced by fabricating the heat-dissipating coating film structure 21 using the dry coating method shown in the present embodiment, as compared with the conventional wet coating method. showing. Conversely, it is possible to maintain the far-infrared emissivity even if the compounding ratio of the resin is increased.

Consideration of the above results will be described. In the method of manufacturing the heat-dissipating coating film structure 21 by wet coating in Comparative Example 1, the cordierite particles are covered with the resin and are less likely to be exposed on the surface of the heat-dissipating coating film structure 21 .

In Comparative Examples 3 and 4, the weight ratio of the cordierite particles is high, and the weight ratio of the resin is small, so that it is difficult to maintain the film strength. On the other hand, in Comparative Examples 5 and 6, the compounding weight ratio of the cordierite particles was low, and conversely, the compounding weight ratio of the resin was large. It is thought that the far-infrared emissivity was lowered because the radiation from the surface was hindered. In other words, in the comparative example, the far-infrared emissivity and film strength cannot be achieved at the same time.

On the other hand, as in Examples 1 to 6, by depositing the composite particles in which the surfaces of the resin particles are coated with the cordierite particles in advance, the surface of the heat-dissipating coating film structure 21 can be coated even with a small amount of the cordierite particle blending ratio. I think it's because I was able to expose it. In addition, it is thought that by decreasing the blending weight ratio of the cordierite particles, the blending weight ratio of the resin can be increased, and the film strength is increased and the durability is improved. Here, the blending weight ratio range of cordierite particles that achieves both far-infrared emissivity and film strength is preferably 66.7 to 50.0%. Further, 62.5 to 55.6% is desirable.

Next, comparison between Examples 1-6 and Examples 7-16 will be described.
The above-mentioned range of the blending weight ratio of the cordierite particles that achieves both the far-infrared emissivity and the film strength is expanded by changing the resin for making the heat-dissipating coating film structure 21 from a thermoplastic resin to a thermosetting resin. is confirmed. Specifically, in Examples 1 to 6 using a thermoplastic resin, the blending weight ratio is preferably 66.7 to 50.0%, preferably 62.5 to 55.6%, whereas the thermosetting resin In Examples 7 to 16 using a curable resin, it is preferably 76.9 to 45.4%, desirably 66.7 to 50.0%.

A consideration of the reason for this result will be described below.
In the case of a thermoplastic resin, the viscosity of the resin tends to decrease due to heating in the arranging process to the heat curing process of manufacturing the heat-dissipating coating film structure 21, and the following phenomenon is likely to occur. If the blending ratio of the resin is large, the resin tends to float on the surface of the heat-dissipating coating structure 21, preventing the cordierite particles from being exposed on the surface of the heat-dissipating coating structure 21. FIG. In addition, when the blending ratio of the resin is small, the resin partially agglomerates in areas where the resin easily flows in the heat-dissipating coating structure 21, resulting in areas where the cordierite particles and the resin do not come into contact with each other, resulting in a decrease in film strength. think it did.

On the other hand, if a thermosetting resin is used in the arranging process and the heat-curing process of manufacturing the heat-dissipating coating film structure 21, the viscosity of the resin is less likely to decrease due to heating. In addition, since the curing progresses while being heated, the phenomenon that the resin rises to the surface of the heat-dissipating coating film structure 21 described above is reduced when the compounding ratio of the resin is large. In addition, when the blending ratio of the resin is small, the cordierite particles are likely to be pushed into the softened resin particles and fixed due to the pressurizing force in the heat curing process, and detachment of the cordierite particles is reduced.
Therefore, the resin constituting the heat-dissipating coating film structure 21 is not particularly limited as long as it is a resin that can be formed into a film by heating and pressurization, but is preferably a thermosetting resin.

In addition, since the surface of the heat-dissipating coating structure 21 produced in this example has partial recesses, and part of the cordierite particles are exposed on the surface of the recesses, the heat-dissipating coating structure 21 This is because the surface area of the cordierite particles was increased and the radiation performance of the cordierite particles could be effectively utilized.

Here, the depth of the recesses is preferably three times or more the average particle size of the cordierite particles. As a result, even if the surface of the heat-dissipating coating structure wears and some of the cordierite particles are detached, the shape of the recesses can be secured, and the cordierite particles exposed on the surface of the recesses can be maintained. can be ensured. Furthermore, it is desirable that the depth of the concave portion is shallower than the average thickness of the heat-dissipating coating film structure 21 . This is because, by setting the thickness to be shallower than the average thickness, the concave portion penetrates the heat-dissipating coating film structure 21 , and deterioration of the heat-dissipating performance due to the exposure of the surface of the aluminum metal plate 20 can be prevented.

Next, for some of the comparative examples and examples, the effect of actual heat dissipation performance was measured by the following method, and the results are shown in Table 2 of FIG.

<Measurement of temperature rise suppression temperature change>
The heat dissipation performance evaluation elements 22 and 23 produced in the example and the comparative example were subjected to temperature rise suppression temperature change measurement with the configuration shown in FIG. A specific configuration of the evaluation apparatus is a configuration in which a heater 24 is laminated on the surface of the heat dissipation performance evaluation element 22 or 23 on which the heat dissipation coating structure is not formed, and a heat insulating plate 25 is laminated on the opposite side of the heater 24 . In addition, the interface between the heat dissipation performance evaluation element 22 or 23 and the heater 24 is placed in close contact with a thermally conductive paste (not shown) in order to avoid the influence of the heat conduction due to the gap at the interface, and the temperature rise suppression temperature change A measuring machine 26 was used.

Next, the temperature rise suppression temperature change measuring device 26 was placed in a constant temperature bath maintained at 25° C., and an electric current was passed through the heater 24 in a state where the temperature was kept constant and no wind was blowing. The voltage was increased, and the temperature of the heater 24 measured in Comparative Example 2 using the heat dissipation evaluation element 23 without the heat dissipation coating structure was used as a reference, and Comparative Example 1 and Example 4 were conducted under the same conditions. The difference ΔT between the temperature of the heater 24 and the temperature of the heater 24 when the heat dissipation performance evaluation element 22 manufactured in Examples 9 and 12 was used was obtained by 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)] (Formula 1)

For example, the temperature difference (ΔT) of the heat dissipation performance evaluation element 22 manufactured in Comparative Example 1 was 2.1° C. (FIG. 11 (Table 2)).
Here, the temperature rise suppression rate can be expressed by Equation 2 below.
Temperature rise suppression rate (%)=ΔT/temperature of heater 24 of Comparative Example 2×100 (Formula 2)
Here, a larger temperature rise suppression rate is preferable, and the measured temperature difference (ΔT) and temperature rise suppression rate are shown in Table 2 of FIG.

The temperature rise suppression rate obtained by the above method was 4.0%, 4.9%, and 5.3% in Examples 4, 9, and 12, compared with 1.7% in Comparative Example 1. Good results were obtained. The factors for this will be explained below.

This temperature rise suppression rate is such that the heat generated from the heater 24 is conducted in the thickness direction of the aluminum metal plate and the heat dissipation coating structure 21 that constitute the heat dissipation performance evaluation element 22, and the heat is transferred from the surface of the heat dissipation coating structure 21. is the evaluation result of the entire heat transfer radiated and dissipated.

Here, the results of Comparative Example 1 and Examples 4, 9, and 12 are considered. The above-mentioned far-infrared emissivity is 0.9 or more, and it is considered that the radiation performance from the surface of the heat-dissipating coating film structure 21 is about the same. Therefore, it is considered that the thermal conductivity in the thickness direction of the heat-dissipating coating film structure 21 is different. Here, in the heat-dissipating coating film structure 21 in this embodiment, the cordierite particles are in contact with the aluminum metal plate in the heat-dissipating coating film structure 21, and the cordierite particles are partially in close contact with each other. It has a structure in which there are places where it is not. Therefore, it is considered that the portions where the cordierite particles are in close contact with each other serve as heat conduction paths, and the heat is easily conducted in the thickness direction of the heat-dissipating coating film structure 21 .

That is, in the conventional method for producing the heat-dissipating coating film structure 21 by wet coating as in Comparative Example 1, the cordierite particles are dispersed in the heat-dissipating coating film structure 21, and the cordierite particles It is thought that the resin is mixed in the contact points between the cordierite particles and the aluminum metal plate and hinders the heat conduction. On the other hand, it is considered that the above-described thermal conductive contacts of the cordierite particles are easily secured in the heat-dissipating coating film structure 21 manufactured by dry coating in this example.

Furthermore, the fact that there are places where cordierite particles are in close contact and places where cordierite particles are not in close contact in the heat-dissipating coating film structure 21 indicates that there are scattered places where there is a large amount of resin. As a result, even if the heat-dissipating coating structure 21 receives physical or thermal stress, the scattered resin has the effect of relieving the stress, and the effect of preventing cracks and peeling of the heat-dissipating coating structure is expected. can. As for the structure within the heat-dissipating coating structure, for example, when an arbitrary portion is cut in the in-plane direction of the heat-dissipating coating structure, there are portions where adjacent cordierite particles are in contact with each other and between adjacent cordierite particles. It is desirable that there is a portion having a distance of 5 times or more the average particle diameter of the cordierite particles. The distance between the adjacent cordierite particles can be controlled by adjusting the average particle size of the resin material used in manufacturing the heat-dissipating coating structure and the heating temperature and pressure applied during the manufacturing process of the heat-dissipating coating structure. is possible.

It should be noted that the present disclosure includes appropriate combinations of any of the various embodiments and / or examples described above, and each embodiment and / or The effects of the embodiment can be obtained.

The heat-dissipating coating structure according to the present disclosure has excellent heat-dissipating properties, reduces deterioration in heat-dissipating performance due to wear and friction, and has resistance to stress caused by temperature changes and external loads.

REFERENCE SIGNS LIST 1 heat-dissipating coating structure 2 heat-dissipating particles 3 resin 4 base material (metal structure)
5 recesses 8 composite particles 9 powder layer 10 voids 11 alignment layer 12 electronic member 13 heat generating device 14 tablet terminal (electronic equipment)
REFERENCE SIGNS LIST 15 heating element 16 substrate 17 tablet housing 20 aluminum metal plate 21 heat dissipation coating structure 22, 23 heat dissipation performance evaluation element

Claims (11)

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 diameter of 0.1 to 30 μm, which are 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 at least 10 times the average particle diameter of the heat-dissipating particles,
a plurality of recesses are present on the surface of the heat-dissipating coating structure,
A heat-dissipating coating structure, wherein a plurality of the 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 said concave portion is at least three times the average particle diameter of said heat-dissipating particles and less than the average thickness of said heat-dissipating coating structure. In the in-plane direction of the heat-dissipating coating structure, a portion where adjacent particles of the heat-dissipating particles are in contact and a portion where the distance between the adjacent particles is 5 times or more the average particle diameter of the heat-dissipating particles. 3. The heat-dissipating coating film structure according to claim 1 or 2, wherein a plurality of and are present. 4. The ratio of the heat-dissipating particles to the total weight of the heat-dissipating particles and the resin in the heat-dissipating coating structure is 45.4 wt % or more and 76.9 wt % or less. 1. The heat-dissipating coating structure according to claim 1. 5. The heat-dissipating coating according to claim 4, wherein a ratio of said heat-dissipating particles to the total weight of said heat-dissipating particles and said resin in said heat-dissipating coating structure is 50.0% by weight or more and 66.7% by weight or less. membrane structure. The heat-dissipating coating film structure according to any one of claims 1 to 5, wherein the resin is a thermoplastic resin made of polyethylene resin, polypropylene resin, or acrylic resin. The heat-dissipating coating structure according to any one of claims 1 to 5, wherein the resin is a thermosetting resin made of epoxy resin, epoxy polyester resin, polyester resin, or acrylic resin. An electronic member having the heat-dissipating coating film structure according to any one of claims 1 to 7 formed thereon. An electronic device having the heat-dissipating coating film structure according to any one of claims 1 to 7 formed on its surface. A composite treatment step of forming composite particles in which heat-dissipating particles are coated on the surface of powder composed of a thermosetting resin;
a powder layer forming step of forming a powder layer in which the composite particles are laminated;
an arranging step of pressurizing or heating the powder layer to reduce voids in the powder layer and forming an oriented layer in which the composite particles are arranged;
a heat curing step of heating the alignment layer to melt the resin once and then cooling it to form a heat-dissipating coating film structure;
A method of manufacturing a thermally conductive coating structure, comprising: 11. The method of manufacturing a heat-dissipating coating film structure according to claim 10, wherein in said heat-curing step, pressure is applied.

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