WO2016024671A1 - Core-shell structured filler for heat-releasing adhesive, having ain-deposited polymeric ball surface, and manufacturing method therefor - Google Patents

Abstract

The present invention relates to a filler for a heat-releasing adhesive, which is formed to have a core-shell structure by depositing AIN on a surface of a polymeric ball. The manufacturing method for a heat-releasing adhesive according to the present invention comprises the steps of: preparing a polymeric ball; pre-treating the polymer ball; forming an AIN film on an external skin of the polymeric ball through a sputtering process in a vacuum chamber; dispersing a filler in a solvent; mixing the filler dispersed liquid and an adhesive solvent; and removing the solvent to complete an adhesive.

Description

A core-cell structured filler for heat dissipation adhesive deposited on the surface of a polymer ball and its manufacturing method

The present invention relates to a filler for a heat dissipating adhesive and a method for manufacturing the same, and more particularly, to a filler for heat dissipating adhesive formed by depositing AIN on the surface of a polymer ball to have a core-cell structure.

As the performance of various electronic components improves, the number of signals processed by each component increases, and thus heat generation of the components increases. If the heat generated by various electronic components cannot be discharged smoothly, performance will be degraded. Recently, this heat dissipation problem is solved by using a thermally conductive tape. This is because light and thin heat dissipation tapes are preferred for each mobile device.

Thermally conductive adhesives include fillers with a smooth flow of heat. For example, AIN (aluminum nitride), which is used as a filler, has superior heat transfer properties than general aluminum. AIN is mainly used for silicone-based adhesives, which are made in powder form and uniformly mixed with the main material of the adhesive.

However, even though AIN is expensive and the powder is uneven, the heat dissipation characteristics tend to be measured differently even when mixed with a certain concentration in the main material of the adhesive. Therefore, a method of manufacturing a filler having a structure having a uniform size and heat dissipation characteristics is required.

The present invention has been made in order to solve the above problems, it is an object of the present invention to provide a filler for a heat-dissipating adhesive that is excellent in heat dissipation characteristics and can be uniformly mixed with the main material.

Adhesive filler according to the present invention is AIN is deposited by sputtering on the surface of the polymer ball.

A method of depositing AIN on the surface of a polymer ball by sputtering according to the present invention comprises the steps of preparing a polymer ball, pre-treating the polymer ball, and forming an AIN film on the outer surface of the polymer ball by a sputtering process in a vacuum chamber. It includes a step.

In addition, after forming the AIN film on the outer shell of the polymer ball further comprises the step of drying the polymer ball. In addition, the polymer ball may be ultrasonicated before the drying step.

The method of manufacturing a heat dissipating adhesive according to the present invention includes the steps of preparing a polymer ball, pretreating the polymer ball, forming a AIN film on the outer surface of the polymer ball by a sputtering process in a vacuum chamber, and a filler. Dispersing in a solvent, mixing a filler dispersion and an adhesive solvent, and removing the solvent to complete the adhesive.

According to the present invention, by depositing AIN on the surface of the polymer ball to have a core-cell structure, it is possible to predict the contact area between the filler and the adhesive has a uniform heat dissipation characteristics.

In addition, due to the deposited AIN has excellent electrical insulation, high temperature thermal conductivity, high bending strength, high temperature stability, and easy post-processing.

In addition, the filler using the existing AIN particles is not easy to control the size distribution, the shape is also uneven, even if distributed evenly on the adhesive layer of the heat dissipation tape, it is difficult to maintain a constant heat dissipation characteristics. The filler in which AIN is deposited on the surface of the polymer ball according to the present invention may have uniform heat dissipation characteristics.

1 illustrates a method of preparing an adhesive after depositing AIN on a polymer ball to form a filler.

2 is an image showing a polymer ball deposited AIN according to the present invention.

3 is a view showing a passage of heat transfer from the adhesive according to the present invention.

Figure 4 shows a conventional AIN particles and a polymer ball deposited AIN according to the present invention.

Hereinafter, a filler of a core-cell structure for a heat radiation adhesive having AIN deposited on a surface of a polymer ball according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Adhesive according to an embodiment of the present invention includes an adhesive solvent, a dispersant and a filler.

The adhesive solvent has adhesiveness and includes an adhesive resin and a crosslinking agent. The adhesive resin is selected from at least one selected from polyvinyl alcohol crab compound, polyurethane compound, polyester compound, polyacrylic compound, and polyepoxy compound, and the crosslinking agent is selected from boric acid, glutaraldehyde, melamine or alcohol solvent At least one or more is selected.

A dispersant for uniformly dispersing the filler is added to the adhesive resin. The dispersant is one or a mixture of saturated hydrocarbon-based esters, ethyl cellosolves of ether alcohols, methyl cellosolves, and ethyl cellosolve acetates.

The filler performs a heat dissipation function in the adhesive. The filler is formed by depositing AIN on the polymer ball, the diameter of which may be formed to 1 ~ 30㎛. Aluminum Nitride (AIN) is called aluminum nitride and has excellent thermal conductivity, high electrical insulation, low thermal expansion rate, and excellent corrosion resistance. AIN has a thermal expansion rate close to that of silicon.

The filler deposits AIN on the polymer balls to form a filler. The polymer ball may be formed of an insulating polymer ball. Insulating polymer balls include nylon resin, polyethylene resin, polypropylene resin, polybutylene, polyester resin, polyurethane resin, polyacrylic resin, polyacryl styrene resin, styrene butadiene resin, vinyl resin, polycarbonate resin, vinyl resin , Fluorocarbon resin, polysulfone, polyethersulfone, polyvinyl butyral resin, polyvinyl formal resin, polyvinylacetate resin, polystyrene resin, styrene divinyl benzene resin, etc. Have

A film is formed by depositing AIN on the outer surface of the polymer ball to prepare a filler. The film of the polymer ball according to the embodiment of the present invention is formed by a sputtering method.

1 illustrates a method of preparing an adhesive after depositing AIN on a polymer ball to form a filler, and FIG. 2 is an image showing a polymer ball on which AIN is deposited according to the present invention.

The method for preparing a heat dissipating adhesive according to the present invention includes the steps of preparing a polymer ball, pretreating the polymer ball, forming a AIN film on the outer surface of the polymer ball by sputtering in a vacuum chamber, and filling the solvent. Dispersing in, mixing the filler dispersion and the adhesive solvent, and removing the solvent to complete the adhesive.

(A) preparing a polymer ball (S100)

A spherical polymer ball having a mean particle size of 1 to 30 µm is prepared. The particle diameter of the polymer ball is preferably larger than the size of at least 3㎛ to have sufficient heat radiation characteristics. The minimum particle diameter of such a polymer ball may be determined according to the precision of the sputtering apparatus.

(B) pretreatment of the polymer balls (S200)

Polymer balls are not easily combined with AIN. For this purpose, the shell of the polymer ball must be modified. In the reforming treatment according to the present invention, plasma treatment is performed in an atmosphere in which argon and oxygen are mixed.

(C) forming an AIN film on the outer surface of the polymer ball by a sputtering process in a vacuum chamber (S300)

First, the vacuum chamber is configured to include a support on which a container containing a polymer ball is placed, a target as a material for coating the outer shell of the polymer ball, and an electrode to protrude atoms of the target material. The particle diameter of the polymer ball is preferably formed to a predetermined size or more for the subsequent sputtering process.

The film of AIN formed by sputtering has a core-shell structure and is formed with a thickness of 0.01 to 0.05 μm. Referring back to Figure 2, the polymer balls forming the filler are formed to have a long length in contact with each other due to the AIN film. Therefore, the fillers have excellent heat dissipation characteristics as a connection structure to each other.

On the other hand, after the plasma process, the fine particles can remove contaminants, moisture and static electricity, etc., but the cohesion between the fine particles can be weakened. In order to increase the cohesion between the fine particles, the fine particles are sonicated. Ultrasonic vibrations cause the particles to rub.

Subsequently, the fine particles are kept at a relative humidity of 25% or less and dried at a temperature atmosphere of about 50 to 80 for at least 12 hours. Preferably, the temperature may be dried from 12 to 18 hours at the relative humidity of about 5% to 25% while gradually increasing from a low temperature to a high temperature.

(D) dispersing the filler in the solvent (S400)

The filler thus prepared is mixed with a solvent selected from ethanol, methanol, propane and acetone. In the present invention, the filler dispersion is prepared by mixing 45 to 55 parts by weight of the filler with respect to 100 parts by weight of the solvent and stirring sufficiently.

(E) step of mixing the filler dispersion and the adhesive solvent (S500)

The filler dispersion prepared in step (D) is mixed with an adhesive solvent. Adhesive resin (adhesive resin) is formed with 60-70 weight part with respect to 100 weight part of adhesive solvents, and mixes a crosslinking agent as remainder. And a dispersant is added for mixing the filler dispersion and the adhesive solvent. The dispersant includes 10 to 20 parts by weight based on 100 parts by weight of the adhesive solvent. The mixing may be mechanical mixing using a stirrer. In an embodiment of the invention it is carried out using an ultrasonic mixer.

(F) removing the solvent to complete the adhesive (S600)

The solvent of step (D) is removed from the mixed adhesive solvent as described above. Removal of the solvent may be performed by applying heat to the ultrasonic mixer in the step (E), it may be performed by a separate solvent removal process. This solvent removal process should reduce the change in physical properties of the adhesive due to the rapid change in temperature.

It will be described below in detail through examples and comparative examples of the adhesive according to the present invention.

<Example>

An acrylic resin having an average particle diameter of 12 µm was used. After the fine particles were subjected to a pretreatment for 30 minutes in an argon atmosphere, an AIN film was formed on the acrylic resin. At this time, the sputtering cathode power is 0.1 to 5kW, the argon gas supplied into the vacuum chamber was used a sputter having 10 to 500sccm, vacuum degree 10mTorr ~ 0.1mTorr.

The AIN film formed by sputtering had a core-shell structure and was formed with an average thickness of 0.04 μm. 15 g of the AIN-coated polymer ball thus formed is mixed with 30 ml of methanol and uniformly dispersed to prepare a filler dispersion.

In addition, an adhesive solvent was prepared by blending 65 parts by weight of epoxy acrylate, 25 parts by weight of peroxy ester, and 10 parts by weight of silica as a dispersant with respect to 100 parts by weight of the adhesive solvent.

Subsequently, the prepared filler dispersion is mixed with the adhesive solvent, uniformly mixed using an ultrasonic mixer, and then the solvent of the filler dispersion is removed. The removal of the solvent is gradually increased in temperature for 30 minutes to 50 minutes from room temperature to 80 ℃ to 90 ℃, then heated in an ultrasonic mixer for 60 minutes, then the heating is stopped in the ultrasonic mixer and the temperature is stopped at room temperature Is performed.

Comparative Example

In order to compare the heat dissipation characteristics of the AIN-deposited filler according to an embodiment of the present invention, 15 g of AIN powder having an average particle diameter of 15 μm was mixed in 30 ml of methanol and uniformly dispersed to prepare a filler dispersion. Subsequently, the solvent contained in the filler dispersion was removed by mixing the adhesive solvent in the same manner as in the above example.

In order to compare the heat dissipation characteristics of the fillers according to the Examples and Comparative Examples, the adhesives according to the Examples and Comparative Examples were applied to the upper part of the polyester film of 20㎛ as a release layer to a thickness of 50㎛, respectively, and dried at 80 ° C. After manufacturing, the copper foil foil with a thickness of 35 micrometers was formed in the upper part of an adhesive agent as a base material layer.

The vertical thermal conductivity of the heat dissipation tape thus formed was performed by the measuring method of ASTM D5470, and the horizontal thermal conductivity was used by Angstrom's method.

Table 1 below shows the electrical conductivity of the Examples and Comparative Examples.

Table 1

division	Vertical thermal conductivity (W / mK)	Horizontal thermal conductivity (W / mK)
Example	2.426	160.889
Comparative example	2.341	152.237

As shown in Table 1, it can be seen that the AIN-deposited filler according to the present invention has excellent heat dissipation effect in the heat dissipation tape. In addition, the AIN according to the present invention may be used as a material for blocking electromagnetic waves as a structure in which the polymer balls are interconnected.

3 is a view showing a passage of heat transfer from the adhesive according to the present invention. Referring to the drawings, heat transferred from one side may be transferred through the AIN film connected to each other to quickly release. Figure 4 shows a conventional AIN particles and a polymer ball deposited AIN according to the present invention. Conventional AIN particles are difficult to maintain a constant heat dissipation characteristics even if they are unevenly formed evenly distributed on the adhesive layer of the heat dissipation tape. The filler in which AIN is deposited on the surface of the polymer ball according to the present invention may have uniform heat dissipation characteristics.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to the said Example, A various deformation | transformation is possible for a person with ordinary knowledge within the scope of the technical idea of this invention.

Claims (5)

1. Adhesive filler characterized in that the AIN is deposited on the surface of the polymer ball by sputtering.
2. As a method of depositing AIN on the surface of the polymer ball by sputtering,

   The method is

   Preparing a polymer ball;

   Pretreating the polymer balls; And

   Forming an AIN film on the shell of the polymer ball by a sputtering process in a vacuum chamber;

   Method of depositing AIN by sputtering on the surface of the polymer ball comprising a.
3. The method according to claim 2,

   Forming an AIN film on the outer shell of the polymer ball, and further comprising the step of drying AIN by sputtering on the surface of the polymer ball, characterized in that it further comprises the step of drying.
4. The method according to claim 3,

   The method of depositing AIN by sputtering on the surface of the polymer ball, characterized in that the polymer ball is ultrasonically treated before the drying step.
5. As a method of manufacturing a heat dissipation adhesive,

   The method is

   Preparing a polymer ball;

   Pretreating the polymer balls;

   Forming an AIN film on the shell of the polymer ball by a sputtering process in a vacuum chamber;

   Dispersing the filler in a solvent;

   Mixing the filler dispersion and the adhesive solvent; And

   Removing the solvent to complete the adhesive;

   Method for producing a heat dissipation adhesive comprising a.

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