KR20220095995A - Coating method of coating solution comprising hexagonal boron nitride particles and heat dissipation member manufactured thereby - Google Patents

Abstract

Disclosed is a coating method for a coating solution comprising hexagonal boron nitride particles that includes: a step of preparing a heat dissipation member; a BN coating step of coating a BN coating solution containing hexagonal boron nitride particles, a binder, and a solvent on the surface of the heat dissipation member; and a high specific gravity particle coating step of coating a high specific gravity particle coating solution containing inorganic or metal powder particles, a binder, and a solvent after the BN coating step.

Description

Coating method of coating solution comprising hexagonal boron nitride particles and heat dissipation member manufactured thereby

The present invention relates to a method for coating a coating solution containing hexagonal boron nitride particles and a heat dissipation member produced thereby, and more particularly, to a surface of a heat dissipation member made of aluminum metal, etc. Coating solution containing hexagonal boron nitride particles having a large specific surface area and greatly increasing thermal radiation energy by applying a coating that directly contacts and fixes hexagonal boron nitride (hereafter referred to as 'h-BN') particles It relates to a coating method and a heat dissipation member manufactured thereby.

In the present specification, the term 'heat dissipation member' is used to comprehensively mean a structure capable of performing a heat dissipation action having various shapes or materials.

It has various materials, structures and shapes that increase the stability and reliability of the heating part by transferring thermal energy from the heating part that generates a lot of heat per unit area, such as light, thin, compact and highly integrated electronic parts or high-output power devices, to the surrounding parts such as the housing and air. Heat dissipation members and heat sinks are widely used.

As an example thereof, as shown in FIG. 1 , a structure for dissipating heat generated in the semiconductor package 1 by directly attaching the heat sink 2 to the body 1a of the semiconductor package 1 is disclosed in Prior Patent 1. has been Here, the heat sink 2 (heat sink) is generally formed with a plurality of heat radiation fins (heat radiation fins) such as plates or rods continuously formed on one surface of the main plate functioning as a heat conduction unit to increase the contact surface area with the outside. have a structure

On the other hand, thermal radiation is a phenomenon in which thermal energy on the surface of a material is converted into electromagnetic wave energy by transfer of thermal energy by radiation and radiated to the surrounding space. The wavelength of the thermal radiation electromagnetic wave is present in the partial range of ultraviolet light (0.1um), visible light, and the entire infrared range (100um). The thermal radiation energy (E) is proportional to the thermal radiance (α), the surface area (A), and the absolute surface temperature (T), and has the behavior of the following Stefan-Boltzmann equation.

E ∝ α * A * T ⁴

The high thermal radiation energy of the surface of the material in contact with the heat source lowers the surface temperature because the thermal energy on the surface of the material is effectively converted into electromagnetic waves. Therefore, the temperature gradient increases from the heat source to the surface, and more heat energy is transferred, thereby showing high heat dissipation performance. According to the above formula, in order to increase the heat radiation energy (E), the heat radiance (α) of the heat radiation surface must be high, the temperature (T) of the heat radiation surface must be high, and the surface area (A) of the heat radiation surface must be large.

In general, aluminum metal, which is mainly used as a heat dissipation fin, has a high thermal conductivity of 300 W/mK level, but a thermal radiance (α) has a very low value of 0.01 level, so based on the Stefan-Boltzmann equation, the thermal radiation energy is small as a result. To compensate for this, black coating or anodizing surface treatment is applied to increase the heat radiation, but at the same time, the surface temperature is lowered, so the heat radiation energy cannot be significantly increased. Therefore, in the case of heat dissipation fins made of aluminum metal, there is a fundamental limit in increasing heat radiation energy only with various types of fin structures that increase the cross-sectional area, and thus, innovative research and development is required to solve this problem.

Republic of Korea Patent Publication No. 10-271637

The present invention has been devised to solve the problems in the prior art as described above, and by coating the surface of a heat dissipating member such as a metal in direct contact with hexagonal boron nitride (h-BN) particles, the thermal radiance, the thermal radiation surface area An object of the present invention is to provide a method for coating a coating solution containing hexagonal boron nitride particles capable of significantly increasing the thermal radiation energy of the surface of a heat dissipating member by simultaneously increasing the surface temperature, and a heat dissipating member manufactured thereby.

In addition, the present invention uses hexagonal boron nitride (h-BN) nanoparticles and micro particles and high specific gravity particles such as inorganic or metal powder particles sequentially and complexly by using hexagonal boron nitride (h-BN) particles as a heat dissipation member. By contacting the surface as much as possible, the method of coating a coating solution containing hexagonal boron nitride particles, which can further increase the thermal radiation degree, the thermal radiation surface area, and the surface temperature to further increase the thermal radiation energy, and a heat radiation member manufactured thereby. to serve a different purpose.

The problem to be solved by the present invention is not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be.

A coating method of a coating solution containing hexagonal boron nitride particles according to an embodiment of the present invention for achieving the above object, comprising the steps of: preparing a heat dissipation member; BN coating step of coating a BN coating solution containing hexagonal boron nitride particles, a binder, and a solvent on the surface of the heat dissipation member; and a high specific gravity particle coating step of coating a high specific gravity particle coating solution including inorganic or metal powder particles, a binder, and a solvent after the BN coating step.

In the above embodiment, the hexagonal boron nitride particles included in the BN coating solution are hexagonal boron nitride particles having a D50 of 10 μm or less, and the high specific gravity particles included in the high specific gravity particle coating solution are high specific gravity particles having a D50 of 20 μm or less. desirable.

In addition, in the above embodiment, the hexagonal boron nitride particles included in the BN coating solution are hexagonal boron nitride nanoparticles having a D50 of 200 nm or less, and hexagonal boron nitride microparticles having a D50 of 1 to 10 μm. It is preferable that they are boron nitride particles.

In addition, in the above embodiment, the BN coating solution is a coating solution mixed in a ratio of 0.05 to 3 parts by weight of hexagonal boron nitride particles, 0.005 to 0.5 parts by weight of binder, and 96.5 to 99.945 parts by weight of solvent, and the high specific gravity particle coating solution has a high specific gravity It is preferable that the coating solution is mixed in a ratio of 0.1 to 5 parts by weight of particles, 0.005 to 0.5 parts by weight of binder, and 94.5 to 99.895 parts by weight of solvent.

In addition, in the above embodiment, the BN coating step, after coating the nano-BN coating solution containing hexagonal boron nitride particles having a D50 of 200 nm or less, and a micro BN coating solution containing hexagonal boron nitride particles having a D50 of 1 to 10 μm It is preferable that the step of coating the

On the other hand, the heat dissipation member according to an embodiment of the present invention, the hexagonal boron nitride particles are in direct contact with the surface of the heat dissipation member, and manufactured by the coating method of the coating solution containing the hexagonal boron nitride particles according to the embodiment characterized by being

In the above embodiment, it is preferable that the hexagonal boron nitride particles having a D50 of 10 μm or less and the high specific gravity particles are sequentially arranged from the surface of the heat dissipating member.

According to one embodiment of the present invention, by coating the surface of the heat dissipating member metal with hexagonal boron nitride (h-BN) particles in direct contact, the low thermal radiance (α), which is a disadvantage of the metal surface, is increased by 50 times or more, and heat radiation Because the surface area (A) is magnified more than 100 times and exhibits a high surface temperature close to that of the metal surface due to high thermal conductivity, the thermal radiation energy (E) can be greatly increased by the Stefan-Boltzmann behavior.

In addition, according to an embodiment of the present invention, since the hexagonal boron nitride nanoparticles are coated to directly contact the surface of the heat dissipating member, the surface area of the heat radiating surface is greatly increased, thereby further increasing the heat radiating energy.

1 is a schematic diagram showing a structure of a metal heat sink according to the prior art,
2 is a schematic diagram showing a cross section of a heat dissipation particle coating layer before final drying of a heat dissipation member according to Examples 1 and 2 of the present invention;
3 is a schematic view showing a cross section of a heat dissipation particle coating layer before final drying of a heat dissipation member according to Comparative Examples 1 to 4;

Hereinafter, specific embodiments in which the present invention may be practiced will be described in detail by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention with respect to one embodiment. Accordingly, the detailed description set forth below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scope equivalents as those claimed.

Compared to aluminum, which is conventionally mainly used as a heat dissipation member, the hexagonal boron nitride (h-BN) material exhibits a similar thermal conductivity of 300 W/mK level and at the same time a high thermal emissivity (α) of 0.9 or more. It has the advantage of being high. In addition, since it can be manufactured with chemically stable nanoparticles, the surface area of the heat dissipating member can be remarkably increased. In addition, the hexagonal boron nitride (h-BN) particles have a higher thermal emissivity (α) due to high energy state density near the bandgap.

Therefore, the hexagonal boron nitride (h-BN) particles coated in contact with the metal surface of the heat dissipation member increase the low thermal emissivity (α), which is a disadvantage of the metal surface, by more than 50 times, and the heat radiation surface area (A) is enlarged by more than 100 times and Due to its high thermal conductivity, it exhibits a high surface temperature close to that of the metal surface, so that the thermal radiation energy (E) can be dramatically increased. As a result, the heat energy of the heat generating source is not accumulated and moved to the heat dissipating member quickly, thereby increasing the stability, reliability, and lifespan of the heat generating source.

When the hexagonal boron nitride particles having such characteristics are to be used as thermal radiation particles, the coating solution containing the hexagonal boron nitride particles is coated on the surface of the heat dissipating member by spraying, applying, or the like, or hexagonal boron nitride It is conceivable to coat a coating solution in which particles and high specific gravity particles such as inorganic or metal powder particles commonly used as thermal radiation particles are mixed.

As schematically shown in Comparative Example 1 of FIG. 3, when only hexagonal boron nitride particles are used, the hexagonal boron nitride particles have a low specific gravity of 2 g/cc, and in the case of nanoparticles, the surface according to the small particle size Due to the effect, the inherent low dispersibility of the hexagonal boron nitride particles, and the plate-like particle shape, it is difficult to directly contact the surface of the heat dissipation member, and the coating layer is formed in a form that is randomly suspended and fixed in the binder. In addition, when mixed with high specific gravity particles such as alumina, as schematically shown in Comparative Example 3 of FIG. 3, the alumina particles have good dispersibility and flowability due to their high specific gravity of 4.0 g/cc and spherical shape. Since it sinks first and comes into contact with the surface of the heat dissipation member, the effect of the h-BN particles is hardly seen, so there is a big limit in increasing the heat radiation energy.

The present inventors have come to the present invention by paying attention to the above technical idea, and the present invention utilizes the above high specific gravity particle characteristics and h-BN characteristics, and through the sinking behavior of high specific gravity particles such as alumina, h- It is characterized in that the BN particles are pressed to contact the surface of the heat dissipation member.

A heat dissipating member coated with hexagonal boron nitride particles according to an embodiment of the present invention, as exemplarily shown in FIG. 2 , includes a heat dissipating member adjacent to a heat source; and micro- or nano-sized hexagonal boron nitride (h-BN) particles having a D50 of 10 μm or less from the surface as heat radiation particles coated on the heat radiation member, and high specific gravity particles such as alumina.

The heat dissipation member coated with hexagonal boron nitride particles according to an embodiment of the present invention as described above is characterized in that it is manufactured by the coating method of the coating solution containing the hexagonal boron nitride particles described below, so the coating method in the following Its structure will become clear through a detailed description of

A coating method of a coating solution containing hexagonal boron nitride particles according to an embodiment of the present invention comprises the steps of preparing a heat dissipation member; BN coating step of coating a BN coating solution containing hexagonal boron nitride particles, a binder, and a solvent on the surface of the heat dissipation member; and a high specific gravity particle coating step of coating a high specific gravity particle coating solution including inorganic or metal powder particles, a binder, and a solvent after the BN coating step.

In the step of preparing the heat dissipating member, the heat dissipating member may be a heat dissipating member of various shapes or materials, such as a plate or a rod shape used in a conventional heat sink structure, and may be a heat dissipating member through a heat conducting unit or the like directly to the heat generating unit It can be used in contact. In addition, the heat dissipation member may be an exposed heat generating unit to which a heat sink is not attached and various packages in which the heat generating unit is embedded.

Next, a BN coating solution containing hexagonal boron nitride particles, a binder, and a solvent is coated on the surface of the heat dissipation member as a heat radiation coating solution.

The main reason for using hexagonal boron nitride particles as heat radiating particles is that they have electrical insulation properties and high thermal conductivity of 300 W/mK level and at the same time high thermal radiation (α) of 0.9 or higher, so many applications requiring electrical insulation This is because it has the advantage of high thermal radiation energy.

In addition, the blending ratio of the binder having relatively low thermal conductivity compared to the hexagonal boron nitride in the coating liquid composition is limited to the minimum amount required for the hexagonal boron nitride particles to directly contact and fix the surface of the heat dissipation member.

As the binder, an organic resin or an inorganic binder may be used. The organic resin includes a thermosetting resin and a thermoplastic resin, and the inorganic binder includes a binder by sol-gel reaction of inorganic materials such as water glass, silicate, MgO, and ZnO. The epoxy resin, which is a typical thermosetting resin, is preferably a low-viscosity liquid epoxy resin at room temperature or a solid low softening epoxy resin at room temperature in order to improve the dispersibility and flowability of the hexagonal boron nitride particles and high specific gravity particles.

The thermosetting epoxy resin may be, for example, at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether of polycarboxylic acid, and epoxy resin obtained by epoxidation of a cyclohexane derivative, Among them, the epoxy resin is preferably an epoxy resin obtained by epoxidation of a bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, or a cyclohexane derivative from the viewpoint of heat resistance and workability. Preferably, a one-component epoxy resin is used.

Examples of the solvent include acetaldehyde, acetylene, acetylene dichloride, acrolein, acrylonitrile, benzene, 1,3-butadiene, butane, 1-butene, 2-butene , carbon tetrachloride, chloroform, cyclohexane, 1,2-dichloroethanediethylamine, dimethylamine, ethylene, formaldehyde, n-hexane, isopropyl alcohol, methanol, methyl ethyl ketone, methylene chloride, MTBE, propylene, Propylene oxide, 1, 1, 1-trichloroethane, trichloroethylene, gasoline, naphtha, crude oil, acetic acid (acetic acid), ethylbenzene, nitrobenzene, toluene, tetrachloroethylene, xylene (o-, m-, p -included), styrene can be used, and ethanol is preferably used. In addition, depending on the type of binder, water may be used as a solvent.

The hexagonal boron nitride particles included in the BN coating solution are hexagonal boron nitride particles having a D50 of 10 μm or less. This is because, when these particles are larger than the size specified on the basis of D50, the colloidal dispersibility of the coating solution deteriorates.

Also, preferably, the hexagonal boron nitride particles having a D50 of 200 nm or less and hexagonal boron nitride nanoparticles having a D50 of 1 to 10 μm are mixed. The reason for using a mixture of two types of particles is to increase the surface area and surface temperature at the same time.

In addition, the BN coating solution is preferably mixed in a ratio of 0.05 to 3 parts by weight of hexagonal boron nitride particles, 0.005 to 0.5 parts by weight of binder, and 96.5 to 99.945 parts by weight of solvent. More preferably, the BN coating solution consists of 0.1 parts by weight of the hexagonal boron nitride particles, 0.01 parts by weight of the binder, and 99.89 parts by weight of the solvent.

When the amount of h-BN particles in the BN coating solution is 3 parts by weight or more, the dispersibility in the coating solution deteriorates and the viscosity increases, making it difficult to exert the pressing effect due to the weight of the high specific gravity particles. decreases. That is, the ratio of the particle fixing binder and the solvent in the coating solution is relatively reduced, so that the h-BN particles do not come into contact with the substrate, so that the thermal radiation energy of the substrate surface is lowered. On the other hand, when the h-BN particle is 0.05 parts by weight or less, the effect of the h-BN particle is not significantly exhibited, and the heat radiation energy of the substrate surface is lowered.

In the case of the binder for fixing the BN coating solution, when it is 0.5 parts by weight or more, the h-BN particles do not directly contact the substrate, so that the heat radiation energy is lowered, and when it is 0.005 parts by weight or less, it is difficult to fix the h-BN particles to the substrate. .

In the case of the solvent of the BN coating solution, when it is 96.5 parts by weight or less, the dispersibility in the coating solution is deteriorated and the viscosity is increased, so that it is difficult to exert the pressing effect due to the weight of the high specific gravity particles. In addition, the high viscosity of the coating solution makes spray coating difficult.

Next, after the step of coating the BN coating solution, a high specific gravity particle coating solution containing high specific gravity particles, a binder, and a solvent is coated.

The high specific gravity particles may be inorganic or metal powder particles having a specific gravity of 3 g/cc or more, and include WO3, SiO2, SnO2, ZrO2, TiO2, Al2O3, Ti2O, MgO, ZnO, SiC, SiN, aluminum, copper, nickel, and silver. It is preferably at least one particle selected from the group comprising. It is sufficient if these high specific gravity particles can perform the role of pressing so that the hexagonal boron nitride particles coated first by their own weight can come into direct contact with the surface of the heat dissipation member. Hereinafter, alumina, which can be typically used, will be described as an example of the high specific gravity particles.

The high specific gravity particles included in the high specific gravity particle coating solution are preferably high specific gravity particles having a D50 of 20 μm or less. If it is more than that, the colloidal dispersibility of the coating solution is deteriorated.

In addition, the high specific gravity particle coating solution is preferably mixed in a ratio of 0.1 to 5 parts by weight of the high specific gravity particles, 0.005 to 0.5 parts by weight of the binder, and 94.5 to 99.895 parts by weight of the solvent. More preferably, the high specific gravity particle coating solution comprises 0.5 parts by weight of the high specific gravity particles, 0.03 parts by weight of the binder, and 99.47 parts by weight of the solvent.

When the high specific gravity particles in the high specific gravity particle coating solution are 5 parts by weight or more, the dispersibility in the coating solution deteriorates and the viscosity increases, so that it is difficult to exert the pressing effect due to the weight of the high specific gravity particles particles, and the h-BN particles are 0.05 weight part If it is less than negative, the effect of coating the particles with high specific gravity does not appear significantly, and the heat radiation energy of the surface of the substrate is lowered.

In addition, in the present invention, the BN coating solution is a nano BN coating solution containing hexagonal boron nitride particles having a D50 of 200 nm or less, and a micro BN coating solution containing hexagonal boron nitride particles having a D50 of 1 to 10 μm. In other words, it is preferable to coat in the order of the nano BN coating solution, then the micro BN coating solution. This is because the pressing effect due to the weight of the high specific gravity particles coated thereon is transmitted to the nano hexagonal boron nitride particles below through the plate-shaped micro-hexagonal boron nitride particles, so that they can be better attached to the surface of the heat dissipation member. . In addition, there is also a factor in which the surface contact of the previously coated particles is strengthened by the injection pressure following the injection of the additional high specific gravity particle coating solution after the coating of the BN coating solution.

As above, the BN coating solution is applied to the surface of the heat dissipation member by spraying, brush painting, or dipping method, and after drying at room temperature, apply the high specific gravity particle coating solution within 1 hour so that the h-BN particles are deposited on the surface of the heat dissipation member. make direct contact. After drying at a temperature of 150° C. or less, the binder is cured to fix and attach the h-BN particles.

In Figure 2, according to an embodiment of the present invention, the hexagonal boron nitride particles contacted to the surface of the aluminum substrate heat dissipation member by sequentially coating the BN coating solution and the high specific gravity particle coating solution, and the high specific gravity particles (alumina particles) thereon A schematic diagram of the location is shown. As in Example 1, using hexagonal boron nitride (h-BN) particles of 10 μm or less and high specific gravity particles of 20 μm or less, by sequentially applying to the surface of a heat dissipating member or object requiring heat radiation, direct contact with the surface of the aluminum substrate heat dissipation member Through the hexagonal boron nitride particles, the surface temperature is lowered by increasing the thermal radiation energy of the surface. That is, the h-BN particles directly contact the surface of the heat dissipation member to enlarge the heat radiation surface area and increase the surface temperature through h-BN's inherent high thermal conductivity to dramatically increase heat radiation energy.

Another embodiment of the present invention is a first BN coating solution containing nano h-BN particles having a size of 200 nm or less based on D50, a second BN coating solution containing micro h-BN particles having a range of 1 to 10 μm based on D50, inorganic or metal Heat radiation energy can be further increased by sequentially coating the high specific gravity particle coating solution containing high specific gravity particles such as powder particles. This is due to the structure in which nano BN particles having a high specific surface area are in direct contact with the surface of the heat dissipation member and micro BN particles are in contact with them. , the nano h-BN particles were sequentially pressed. In addition, after coating of the BN coating solution, there is also a factor in which the surface contact of the particles coated first is strengthened by the spraying pressure according to the subsequent additional spraying.

Hereinafter, the composition of the coating solution and the properties according to the coating method will be comparatively described through specific examples and comparative examples. In this case, in both Examples and Comparative Examples, since the coating thickness is controlled by the number of spray sprays, the number of particles present in the coating layer, ie, the amount of filler, increases proportionally according to the coating thickness.

As the heat dissipation member in contact with the heat source, an aluminum substrate having a width*length*thickness of 20*100*2 mm was commonly used, and schematic views of the cross-section of each coating layer are shown in FIGS. 2 and 3 .

(Example 1)

h-BN particles of 200 nm or less and h-BN particles within the range of 1 to 10 μm are mixed at a weight ratio of 1:3 h- This is an example in which BN particles and alumina particles of 20 μm or less are sequentially coated.

To this end, first, a BN coating solution containing 100 g of solvent MEK (Methyl Ethyl Ketone), 0.01 g of epoxy resin Epoxy Adhesive 2214 (3M), and 0.1 g of the h-BN particles is prepared. At this time, use a high-dispersion stirrer to increase the dispersibility. In addition, an alumina coating solution containing 100 g of the solvent, 0.02 g of the epoxy resin, and 0.5 g of the alumina particles is prepared. At this time, use a high-dispersion stirrer to increase the dispersibility. After applying the BN coating solution to the metal surface in a 20um thickness by spraying, it is dried at room temperature. After that, the alumina coating solution is applied to a thickness of 20 μm within 1 hour, then dried at room temperature for 1 hour and dried at 150° C. for 30 minutes.

(Example 2)

To ensure that the nano h-BN particles are attached to and fixed in direct contact with the metal surface of the aluminum heat dissipation member, h-BN particles of 200 nm or less, h-BN particles within the range of 1 to 10 μm, and alumina particles of 20 μm or less are sequentially coated. Example.

To this end, first, a first BN coating solution containing 100 g of the solvent, 0.01 g of the epoxy resin, and 0.1 g of the h-BN particles of 200 nm or less is prepared. A second BN coating solution containing 100 g of the solvent, 0.01 g of the epoxy resin, and 0.1 g of h-BN particles within the range of 1 to 10 μm is prepared. An alumina coating solution containing 100 g of the solvent, 0.02 g of the epoxy resin, and 0.5 g of the alumina particles is prepared. At this time, when making each coating solution, use a high-dispersion stirrer to increase the dispersibility. The first BN coating solution is applied to the metal surface to a thickness of 5 μm by spraying, and then dried at room temperature. After that, the second BN coating solution is applied to the metal surface to a thickness of 15 μm by spraying within 30 minutes, and then dried at room temperature. After that, the alumina coating solution is applied to a thickness of 20 μm within 1 hour, then dried at room temperature for 1 hour and dried at 150° C. for 30 minutes.

(Comparative Example 1)

This is a comparative example in which h-BN particles of 200 nm or less and h-BN particles of 1 to 10 μm in a 1:3 weight ratio are coated on the metal surface of an aluminum heat dissipation member with h-BN particles of 10 μm or less, based on D50.

To this end, first, a coating solution containing 100 g of the solvent, 0.01 g of the epoxy resin, and 0.1 g of the hBN particles is prepared. At this time, use a high-dispersion stirrer to increase the dispersibility. This coating solution is applied to the metal surface with a thickness of 40 μm by spraying, dried at room temperature for 1 hour, and then dried at 150° C. for 30 minutes.

(Comparative Example 2)

This is a comparative example in which alumina of 20 μm or less was coated on the metal surface of an aluminum heat dissipation member based on D50.

To this end, first, a coating solution containing 100 g of the solvent, 0.02 g of the epoxy resin, and 0.5 g of the alumina particles is prepared. At this time, use a high-dispersion stirrer to increase the dispersibility. This coating solution is applied to the metal surface with a thickness of 40 μm by spraying, dried at room temperature for 1 hour, and then dried at 150° C. for 30 minutes.

(Comparative Example 3)

Comparison of single coating by mixing h-BN particles of 200 nm or less, h-BN particles within the range of 1 to 10 μm in a 1:3 weight ratio on the metal surface of aluminum heat dissipation member, and 20 μm alumina Yes.

To this end, first, a coating solution containing 100 g of the solvent, 0.015 g of the epoxy resin, 0.1 g of the h-BN particles, and 0.5 g of the alumina particles is prepared. At this time, use a high-dispersion stirrer to increase the dispersibility. This coating solution is applied to the metal surface with a thickness of 40 μm by spraying, dried at room temperature for 1 hour, and then dried at 150° C. for 30 minutes.

(Comparative Example 4)

This is an example in which only the aluminum substrate is present without coating the coating solution on the surface of the aluminum substrate in contact with the heat source.

Total coating layer thickness (um) The number of h-BN particles present in the coating layer The number of alumina particles present in the coating layer Total number of particles present in the coating layer Example 1 40 A B A + B Example 2 40 A B A + B Comparative Example 1 40 2*A 0 2*A Comparative Example 2 40 0 2*B 2*B Comparative Example 3 40 A B A + B Comparative Example 4 0 0 0 0

Table 1 shows the total weight of the particles present in the coating layer as a relative value. In this case, A is the number of h-BN particles present in the coating layer of the corresponding thickness, and B is the number of alumina particles present in the coating layer of the corresponding thickness. The number of the particles is proportional to the weight of the particles. Here, it is known that the intrinsic thermal conductivity performance of material A is three times higher than that of B, assuming a random arrangement.

Prepare the aluminum substrate heat-dissipating member manufactured as above and dried by spraying the heat-radiating coating solution, and set the target temperature to 120°C using a hot plate with digital temperature setting as a heat source. After reaching the target temperature, the coated heat dissipation member is placed on the hot plate. By measuring the temperature of the surface of the heat dissipation member coated with a thermocouple thermometer, the heat radiation energy was indirectly evaluated. The average value measured 5 times is shown in comparison to Table 2 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 coating particles
(based on D50) - h-BN under 10um
- 20um or less alumina - Nano h-BN under 200nm
- 10um micro h-BN
- 20um or less alumina - h-BN under 10um - 20um or less alumina Same as Example 1 X Coating method BN coating solution, alumina coating solution sequential coating 1 BN coating solution,
2nd BN coating solution, alumina coating solution sequentially coating 1 coat 1 coat particle mixture
1 coat X Aluminum substrate surface temperature (℃) 80.3 78.5 88.1 87.2 84.2 92.0

By measuring the temperature of the surface of the heat dissipation member as described above, it was confirmed that Examples 1 and 2, in which individual coating solutions were sequentially coated, had superior heat radiation effect compared to Comparative Examples.

In the case of Comparative Examples 1 and 3, the hexagonal boron nitride particles had a low specific gravity of 2 g/cc and a surface effect due to a small particle size, low dispersibility inherent in the hexagonal boron nitride particles, and low flowability due to the plate shape. It seems that there is a limit to the heat radiation effect because it is fixed in a floating state without direct contact with the surface of the heat dissipating member in contact with the heat source. To overcome this, a sequential coating method of individual coating solutions according to Examples 1 and 2 of the present invention is proposed. In the process of sinking by gravity due to the high specific gravity and high flowability of the spherical shape of the alumina particles, the heat radiation energy is greatly increased by pressing the h-BN particles that are coated first and are close to the heat dissipating member substrate and directly contact the surface. In addition, after coating of the BN coating solution, there is also a factor in which the surface contact of the particles coated first is strengthened by the spraying pressure according to the subsequent additional spraying. In Comparative Examples 1 and 3, as a single coating of the mixed solution, the number of h-BN particles in direct contact with the surface of the aluminum substrate is relatively very small, so that the heat radiation energy is lowered.

In the case of Example 2 compared to Example 1, the first coated nano h-BN particles were later pressed by the coated microplate-shaped h-BN particles, and due to the effect that they were pressed again by the alumina particles, it was in direct contact with the aluminum substrate surface. Since the h-BN nanoparticles are greatly increased, the heat radiation energy is further increased.

As a result, by applying a coating that fixes the hexagonal boron nitride (h-BN) particles in direct contact with the metal surface of the heat dissipating member, the low thermal emissivity (α), which is a disadvantage of the metal surface, is increased by more than 50 times, and the heat radiation surface area (A ) is magnified by more than 100 times and exhibits a surface temperature close to that of the metal surface due to high thermal conductivity, so that the thermal radiation energy (E) can be greatly increased. In addition, since the hexagonal boron nitride nanoparticles and microparticles are coated to sequentially directly contact the surface of the heat dissipating member, the surface area and surface temperature of the heat radiation surface are increased, thereby greatly increasing heat radiation energy.

Due to this, the heat radiation energy of the surface of the heat dissipating member in contact with the heat source is increased to lower the temperature of the surface, so that the heat dissipation effect of transferring more heat energy from the heat source to the surface is increased.

Claims (7)

preparing a heat dissipation member;
BN coating step of coating a BN coating solution containing hexagonal boron nitride particles, a binder, and a solvent on the surface of the heat dissipation member; and
After the BN coating step, a high specific gravity particle coating step of coating a high specific gravity particle coating solution containing inorganic or metal powder particles, a binder, and a solvent;
A method of coating a coating solution containing hexagonal boron nitride particles. The method according to claim 1,
The hexagonal boron nitride particles included in the BN coating solution are hexagonal boron nitride particles having a D50 of 10 μm or less, and the inorganic or metal powder particles included in the high specific gravity particle coating solution have a D50 of 20 μm or less. A method of coating a coating solution containing particles. 3. The method according to claim 2,
The hexagonal boron nitride particles contained in the BN coating solution are hexagonal boron nitride particles in which hexagonal boron nitride nanoparticles having a D50 of 200 nm or less and hexagonal boron nitride microparticles having a D50 of 1 to 10 μm are mixed. A method of coating a coating solution containing boron nitride particles. The method according to claim 1,
The BN coating solution is a coating solution mixed in a ratio of 0.05 to 3 parts by weight of hexagonal boron nitride particles, 0.005 to 0.5 parts by weight of binder, and 96.5 to 99.945 parts by weight of solvent, and the high specific gravity particle coating solution is 0.1 to 5 parts by weight of high specific gravity particles, A coating method of a coating solution containing hexagonal boron nitride particles, which is a coating solution mixed in a ratio of 0.005 to 0.5 parts by weight of a binder and 94.5 to 99.895 parts by weight of a solvent. The method according to claim 1,
The BN coating step is a step of coating the nano BN coating solution containing the hexagonal boron nitride particles having a D50 of 200 nm or less, and then coating the micro BN coating solution containing the hexagonal boron nitride particles having a D50 of 1 to 10 μm. A method of coating a coating solution containing crystal boron nitride particles. Hexagonal boron nitride particles are in direct contact with the surface of the heat dissipation member,
A heat dissipation member manufactured by the coating method of the coating solution containing the hexagonal boron nitride particles according to any one of claims 1 to 5. 7. The method of claim 6,
A heat dissipating member manufactured by a coating method of a coating solution containing hexagonal boron nitride particles, wherein hexagonal boron nitride particles having a D50 of 10 μm or less and high specific gravity particles are sequentially disposed from the surface of the heat dissipating member.

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