KR101909078B1 - Filler and slurry for thermally conductive pad comprising polymer of high filling rate and thermally conductive pad including the same - Google Patents

Abstract

The present invention relates to a filler for a polymer heat-radiating pad, a slurry and a polymer heat-radiating pad comprising the same, and more particularly to a filler comprising particles having different mean particle diameters, wherein the filler is coated by coating the surface of the small particle, To an improved polymeric heat-radiating pad filler, a slurry and a polymeric heat-radiating pad comprising the same.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a filling material for a polymer heat-dissipating pad having a high filling ratio, a slurry, and a polymer heat-dissipating pad comprising the same. [0002]

The present invention relates to a filler for a polymer heat-radiating pad, a slurry and a polymer heat-radiating pad comprising the same, and more particularly to a filler comprising particles having different mean particle diameters, wherein the filler is coated by coating the surface of the small particle, To an improved polymeric heat-radiating pad filler, a slurry and a polymeric heat-radiating pad comprising the same.

With the high integration and high performance of electronic devices and the development of LED lighting, more heat is generated in the device. Such discharge heat shortens the function of the device, the malfunction of the device, and the life of the device.

On the other hand, a heat-radiating pad is a structure that acts as a thermal interface material (TIM) which is positioned between a heat source and an heat sink of an electronic device and transfers heat generated from the heat source to a heat sink.

The main ingredient of the heat-dissipating pad that forms the market is mostly (hydroxide) alumina (Al ₂ O ₃ ), and it is made into a pad form by adding it to silicone resin and sold as a heat pad or a silicone pad.

These heat-radiating pads are required to have thermal conductivity, strength, adhesiveness, and insulation. Among them, the thermal conductivity, which is considered to be the core of heat dissipation, is only about 1 to 2 W / mK.

The heat release pad of Korean Patent Laid-Open Publication No. 2005-0015064 (published on Feb. 21, 2005) is made of a silicon pad containing aluminum or the like as a filler and the surface thereof is subjected to surface modification of accelerated plasma ion particles and surface bonding of reactive gas However, there is a problem that the plasma surface modification is inferior in economy and the surface bonding of the reactive gas is low in efficiency.

Korean Patent Laid-Open Publication No. 2011-0013907 (published on February 10, 2011) uses silver particles coated with a silver oxide film as a filler in a silicone resin and the like, In the same way, there is a problem that the economy is poor.

Therefore, there is a growing demand for a heat-dissipating pad material having excellent thermal conductivity and excellent economical efficiency by using a low-cost material.

Korean Patent Publication No. 2005-0015064 (published on Feb. 21, 2005) Korean Patent Publication No. 2011-0013907 (published on February 10, 2011)

Disclosure of the Invention The present invention has been conceived to solve the problems as described above. It is an object of the present invention to provide a filler for a polymer heat-radiating pad, which comprises a filler composed of particles having different average particle diameters, The purpose is to provide.

It is still another object of the present invention to provide a polymer heat-radiating pad comprising the filler.

It is still another object of the present invention to provide a slurry for a polymer heat-release pad comprising the filler and for producing the polymer heat-release pad.

The filler for a polymer heat-radiating pad of the present invention, in order to achieve the above-

A first filler having a first average particle size and a second filler having a second average particle size,

Wherein the first average particle diameter value is larger than the second average particle diameter value,

The second average particle diameter / the first average particle diameter is 0.05 to 0.46, preferably 0.05 to 0.45, more preferably 0.06 to 0.43, further preferably 0.07 to 0.2, even more preferably 0.08 to 0.15,

The surface of the second filler is coated with a coating agent,

The volume resistances of the first filler and the second filler are 10 ¹⁰ ? Cm or more, preferably 10 ¹² ? Cm or more, more preferably 10 ¹⁴ ? Cm or more.

The particle size distribution of the second filler may have 1 to 10 peaks, preferably 1 to 7 peaks, more preferably 1 to 5 peaks, and more preferably 1 to 4 peaks.

The first filler and the second filler may have an average value of the short diameter / long diameter of 0.8 to 1, preferably 0.82 to 1, more preferably 0.85 to 1, and still more preferably 0.9 to 1.

The first average particle size may be 45 to 200 mu m, preferably 45 to 150 mu m, more preferably 45 to 100 mu m, further preferably 45 to 60 mu m.

The sum of the second filler mass / the first filler mass is preferably 10% to 100%, preferably 20% to 90%, more preferably 30% to 80%, still more preferably 40% to 70% %. ≪ / RTI >

The first filler and the second filler may be at least one selected from the group consisting of Al ₂ O ₃ , BN, AlN, Si ₃ N ₄ , MgO, Beryl, May be selected from the group consisting of zinc oxide (ZnO), silicon carbide (SiC), zirconia (ZrO ₂ ), and mixtures thereof.

The coating agent may be at least one selected from the group consisting of polyethylene, polypropylene, polystyrene, polyester, polyamide, polyether, polycarbonate, acrylic resin, urethane resin, vinyl resin, silicon resin, phenol resin, fluororesin, ≪ / RTI > copolymers.

In addition, the thickness of the coating material coated on the surface of the second filler may be 1 nm to 1 탆, preferably 10 to 800 nm, more preferably 20 to 500 nm, and still more preferably 30 to 300 nm.

On the other hand, the polymer heat-

Polymers and

And a filler for the polymer heat-radiating pad.

The content of the filler for the polymer heat-radiating pad in the polymer heat-dissipating pad may be 50 to 90% by volume, preferably 55 to 80% by volume, more preferably 60 to 70% by volume.

In addition, the content of the filler for the polymer heat-radiating pad in the polymer heat-radiating pad may be 80 to 97% by weight, preferably 84 to 95% by weight, more preferably 86 to 94% by weight.

In addition, the polymer may be selected from the group consisting of a silicone resin, an epoxy resin, an acrylic resin, a mixture thereof, and a copolymer thereof.

On the other hand, the slurry for the polymer heat-

Monomers and

And a filler for the polymer heat-radiating pad.

In addition, the slurry for the polymer heat-release pad may further comprise a solvent.

Further, the monomer

Silanol,

Bisphenol A and epichlorohydrin,

Acrylic acid or acrylic acid ester, and

And mixtures thereof.

The viscosity of the polymer heat-release pad slurry of the present invention is 1,000 to 80,000 cPs, preferably 2,000 to 75,000 cPs, more preferably 3,000 to 70,000 cPs, still more preferably 4,000 to 65,000 cPs, still more preferably 5,000 To 60,000 cPs.

The polymer heat-radiating pad according to the present invention is characterized by coating a surface of a particle including a filler composed of particles having different average particle diameters and having a small average particle diameter. Accordingly, the present invention can more densely fill the filler in the heat-radiating pad, which promotes heat transfer through the filler, resulting in an overall increase in thermal conductivity. Best Mode for Carrying Out the Invention The present invention is advantageous in that the thermal conductivity can be improved only by a simple surface treatment without introducing an expensive component separately, thereby being excellent in economical efficiency.

1 is a conceptual diagram of a state in which the fillers of the present invention are filled.
2 is a photograph of one embodiment of the first filler constituting the present invention.
Fig. 3 is a photograph of one embodiment of the second filler constituting the present invention. Fig.
4 is a photograph showing the flowability of the slurry for the polymer heat-release pad of the present invention.
5 is a photograph showing the flowability of a slurry for a polymer heat-radiating pad in which the second filler is not coated.

Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description, numerous specific details, such as specific elements, are set forth in order to provide a thorough understanding of the present invention, and it is to be understood that the present invention may be practiced without these specific details, It will be obvious to those who have knowledge of. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In order to improve the thermal conductivity of the heat-radiating pad, the present invention includes two filler groups having different average particle diameters, and the filler having a small average particle diameter has the surface coating.

As shown in FIG. 1, it is preferable that the charged particles are filled with as much particles as possible in a predetermined volume, so that the particles contact with each other as much as possible. Therefore, even an empty space between large particles needs to be filled with small particles of an appropriate size. However, generally used filler particles have a rough surface as shown in Fig. As a result, an irregular space is created between the particles, so it is difficult to achieve the theoretical dense filling as in Fig.

In order to solve this problem, coating of large particles with a polymer improves the filling rate, but the heat radiation characteristic of the heat radiation pad is deteriorated due to the low thermal conductivity of the polymer.

Therefore, the present invention is characterized in that only small particles having a relatively low specific gravity contributing to thermal conduction are coated with a polymer to smooth the surface thereof. As shown in FIG. 3, the smooth surface of the small particles enhances the particle filling rate as a whole, promotes heat transfer between the large particles, and consequently improves the heat radiation characteristics of the heat-radiating pad of the present invention.

That is, the filler for a polymer heat-radiating pad of the present invention includes a first filler having a first average particle diameter and a second filler 20 having a second average particle diameter smaller than the first average particle diameter.

The second filler 20 constituting the present invention fills the space between the first fillers 10 and has a second average particle diameter / first average particle diameter of 0.05 to 0.46, preferably 0.05 to 0.45, more preferably 0.06 To 0.43, more preferably 0.07 to 0.2, still more preferably 0.08 to 0.15. If the second average particle diameter / the first average particle diameter is less than 0.05, the first filler 10 may not contact the first filler 10, resulting in spacing. On the contrary, if the first filler 10 exceeds 0.46, the first fillers 10 may not contact each other, The result is a lowering of the heat radiating property of the heat radiating pad of the present invention.

The second filler 20 does not require a separate particle size condition other than an average particle size range satisfying the above-mentioned conditions, and in particular, the second filler 20 has 2 to 10, preferably 2 to 10, It is also possible to have 7 peaks, more preferably 2 to 5 peaks, more preferably 2 to 4 peaks. It is possible to further increase the filling rate by filling the space between the relatively large second fillers 20 with the relatively small second fillers 20. [

The first filler 10 and a second volume resistivity of the filler 20 is 10 ¹⁰ Ωcm or more, preferably not less than 10 ¹² Ωcm, there is is more preferably 10 ¹⁴ Ωcm or more requirements, the volume resistivity less than 10 ¹⁰ Ωcm There is a danger that a short circuit will occur when an electric current is applied to the electronic product to which the present invention is applied.

As the first filler 10 and the second filler 20 constituting the present invention, a material having the thermal conductivity required for the heat radiation pad and having a volume resistance value in the same range as described above is made of alumina (Al ₂ O ₃ , ), boron nitride (BN), aluminum nitride (AlN), silicon nitride (Si ₃ N _4), magnesia (MgO), beryllia (BeO), zinc oxide (ZnO), silicon carbide (SiC), zirconia (ZrO ₂₎ And mixtures thereof.

The filler constituting the heat-radiating pad of the present invention is characterized in that the space between the large first fillers (10) is filled with a small second filler (20). For this purpose, it is preferable that the shape of particles constituting the filler is spherical as shown in Figs. 1 to 3.

Specifically, the first filler 10 and the second filler 20 have an average value of the short diameter / long diameter of 0.8 to 1, preferably 0.82 to 1, more preferably 0.85 to 1, and still more preferably 0.9 to 1 . When the average value of the short diameter / long diameter is 0.8 to 1, the space between the large filler particles can be completely filled and the heat radiation characteristic can be improved.

The first average particle size of the first filler 10 as the largest filler is 45 to 200 mu m, preferably 45 to 150 mu m, more preferably 45 to 100 mu m, still more preferably 45 to 60 mu m Mu m. When the first average particle diameter is in the range of 45 to 200 탆, an appropriate viscosity range can be maintained when mixing with the polymer, ensuring workability and keeping the surface of the final heat-radiating pad smooth.

And, it is preferable that the small filler is added so as to fill the space formed by the large filler, because it can fill the space without separating the large filler. In this respect, the sum of the mass of the second filler 20 / the mass of the first filler 10 is preferably 10% to 100%, preferably 20% to 90%, more preferably 30% to 80% To < RTI ID = 0.0 > 70%. ≪ / RTI >

The coating agent 30 for coating the second filler 20 is not limited as long as it smoothes the surface of the second filler 20. The filler 20 may be made of a material such as polyethylene, polypropylene, polystyrene, polyester, polyamide, polyether, polycarbonate, Acrylic resin, urethane resin, vinyl resin, silicon resin, phenol resin, fluororesin, urea resin, mixtures thereof, and copolymers thereof.

The thickness of the coating 30 coated on the surface of the second filler 20 is 1 nm to 1 탆, preferably 10 to 800 nm, more preferably 20 to 500 nm, still more preferably 30 to 300 nm nm. When the thickness of the coating 30 is within the above range, it is possible to achieve a sufficient lubrication effect while preventing excessive decrease of the heat transfer rate due to the addition of the coating layer, so that the viscosity of the mixture can be properly maintained.

On the other hand, the polymer heat-radiating pad of the present invention is characterized by including a polymer, and a filler for the above-mentioned polymer heat-radiating pad.

The content of the filler for the polymer heat-radiating pad in the polymer heat-radiating pad of the present invention is 50 to 90% by volume, preferably 55 to 80% by volume, more preferably 60 to 70% by volume or 80 to 97% 84 to 95% by weight, more preferably 86 to 94% by weight, and when the content of the filler is in the above range, all of the filler can be immersed in the polymer and a viscosity range of a level easy to work can be achieved.

The polymer may be selected from the group consisting of a silicone resin, an epoxy resin, an acrylic resin, a mixture thereof, and a copolymer thereof.

On the other hand, the present invention also protects a slurry which becomes a polymer heat radiation pad when cured. Such a slurry for a polymer heat-release pad of the present invention is characterized by containing a monomer and a filler for the polymer heat-release pad.

In the present invention, when the second filler is coated to smooth the surface, not only the above-described filling rate can be improved but also the viscosity of the slurry for the polymer heat-radiating pad is lowered as shown in Fig. When the shape of the polymer heat-dissipating pad is determined through a mold, a template, an injection, etc., the slurry must be well filled in every corner of the space they provide. However, if the viscosity of the slurry is high as shown in FIG. 5, the edges and corners can not be filled and an empty space is formed, thereby causing defects.

In the present invention, in order to solve such a problem, it was possible to solve the problem by smoothening the surface of a relatively small filler as described above while repeating the experiment for decreasing the viscosity of the slurry.

Further, the slurry for the polymer heat-release pads of the present invention may further include a solvent such that the monomers and the filler are uniformly dispersed and hardened at a desired time. The solvent constituting the slurry for the polymer heat-release pad of the present invention is not particularly limited as long as it can perform the above functions.

In addition, the monomers constituting the slurry for the polymer heat-release pad of the present invention may be selected from the group consisting of silanol, bisphenol A and epichlorohydrin, acrylic acid or acrylic ester, and mixtures thereof .

The viscosity of the polymer heat-release pad slurry of the present invention is 1,000 to 80,000 cPs, preferably 2,000 to 75,000 cPs, more preferably 3,000 to 70,000 cPs, still more preferably 4,000 to 65,000 cPs, still more preferably 5,000 To 60,000 cPs. When the slurry viscosity of the present invention is within the above-mentioned range, appropriate flowability is exhibited, and workability is improved while exhibiting sufficient thermal properties.

Hereinafter, embodiments of the present invention will be described.

Example

Example 1: Preparation of heat-radiating pad (1)

40 g of alumina having an average particle diameter of 5 μm and an average value of a short diameter / long diameter of 1 was mixed with an acrylate emulsion, and then the above acrylate was emulsion-polymerized to form a 100 nm thick polyacrylate To form a coating layer. 40 g of the coated alumina having an average particle size of 5 mu m was impregnated with 10 g of a silicon resin (Wacker, Germany) melted together with 60 g of alumina having an average particle size of 50 mu m and an average value of the minor axis / minor axis of 1 (Shinil Silicum Material Co., And the polymer heat-radiating pad of the present invention was produced through a heating and pressing process at 115 ° C and 20 kg _f / cm ² , and the thermal conductivity was measured to be 5.2 W / mK. Table 1 shows the porosity (porosity meter, Fisher Scientific, USA) and tap density (powder properties meter, Bettersize Instrument, China) and viscosity (BROOKFIELD, USA).

Comparative Example 1: Preparation of heat-radiating pad (2)

The same procedure as in Example 1 was carried out, except that alumina having an average particle diameter of 5 μm was not coated. In this case, the thermal conductivity was 5.1 W / mK. The porosity, tap density and viscosity are shown in Table 1.

Comparative Example 2: Preparation of heat-radiating pad (3)

The same procedure as in Example 1 was carried out and only 100 g of alumina having an average particle diameter of 50 μm was used. In this case, the thermal conductivity was 4.0 W / mK. The porosity, tap density and viscosity are shown in Table 1.

Comparative Example 3: Preparation of heat-radiating pad (4)

The same procedure as in Example 1 was carried out and only 100 g of alumina having an average particle diameter of 5 탆 was used. In this case, the thermal conductivity was 3.2 W / mK. The porosity, tap density and viscosity are shown in Table 1.

Porosity (%) Tap density (g / ml) Viscosity (cPs) Example 1 33.5 2.94 52,800 Compare to 1 34.8 2.82 100,200 Compare to 2 44.2 2.35 123,000 Compare to 3 48.0 2.44 220,100

Comparative Example 4: Preparation of heat-radiating pad (5)

The same procedure as in Example 1 was carried out, except that alumina having an average particle diameter of 35 μm was used instead of alumina having an average particle diameter of 5 μm. In this case, the thermal conductivity was 3.8 W / mK.

Comparative Example 5: Preparation of heat-radiating pad (6)

The same procedure as in Example 1 was carried out, and alumina having an average value of a short diameter / long diameter of 0.5 was used. In this case, the thermal conductivity was 2.9 W / mK.

Comparative Example 6: Preparation of heat-radiating pad (7)

The same procedure as in Example 1 was carried out, and 99 g of alumina having an average particle diameter of 50 μm and 1 g of alumina having an average particle diameter of 5 μm were used. In this case, the thermal conductivity was 4.0 W / mK.

Comparative Example 7: Preparation of heat-radiating pad (8)

35 g of alumina having an average particle diameter of 50 탆 and 65 g of alumina having an average particle diameter of 5 탆 were used and the thermal conductivity was 3.6 W / mK in this case.

Comparative Example 8: Preparation of heat-radiating pad (9)

The same procedure as in Example 1 was carried out. The thickness of the coating layer of alumina having an average particle diameter of 5 탆 was 10 탆, and the thermal conductivity was 3.5 W / mK in this case.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course it is possible. Accordingly, the scope of the present invention should not be construed as being limited to the above-described embodiments, but should be determined by equivalents to the appended claims, as well as the following claims.

10: first filler 20: second filler
30: Coating Arrow: Heat conduction direction

Claims (13)

A first filler having a first average particle size and a second filler having a second average particle size,
Wherein the first average particle diameter value is larger than the second average particle diameter value,
The second average particle diameter / the first average particle diameter is 0.05 to 0.46,
The surface of the second filler is coated with a coating agent,
The volume resistivity of the first filler and the second filler is 10 ¹⁰ ? Cm or more,
The coating agent may be selected from the group consisting of polyethylene, polypropylene, polystyrene, polyester, polyamide, polyether, polycarbonate, acrylic resin, urethane resin, vinyl resin, phenol resin, fluororesin, urea resin, ≪ / RTI > The method according to claim 1,
Wherein the first filler and the second filler have an average value of a short diameter / a long diameter of 0.8 to 1. The method according to claim 1,
Wherein the first average particle diameter is 45 to 200 占 퐉. The method according to claim 1,
Wherein the sum of the second filler mass / the first filler mass is between 10% and 100%. The method according to claim 1,
The first filler and the second filler include alumina (Al ₂ O _3), boron nitride (BN), aluminum nitride (AlN), silicon nitride (Si ₃ N _4), magnesia (MgO), beryllia (BeO), zinc oxide ( ZnO), silicon carbide (SiC), zirconia (ZrO ₂ ), and mixtures thereof. The method according to claim 1,
Wherein the thickness of the coating agent coated on the second filler surface is 1 nm to 1 占 퐉. Polymers and
A polymer heat-dissipating pad comprising a filler for a polymer heat-release pad of any one of claims 1 to 6. The method of claim 7,
Wherein the content of the filler for the polymer heat-dissipating pad in the polymer heat-dissipating pad is 50 to 90% by volume. The method of claim 7,
Wherein the content of the filler for the polymer heat-radiating pad in the polymer heat-radiating pad is 80 to 97 wt%. The method of claim 7,
Wherein the polymer is selected from the group consisting of a silicone resin, an epoxy resin, an acrylic resin, a mixture thereof, and a copolymer thereof. Monomers and
A slurry for a polymer heat release pad comprising a filler for a polymer heat release pad of any one of claims 1 to 6. The method of claim 11,
Wherein the slurry for the polymer heat-release pad further comprises a solvent. The method of claim 11,
The monomer
Silanol,
Bisphenol A and epichlorohydrin,
Acrylic acid or acrylic acid ester, and
And mixtures thereof. ≪ RTI ID = 0.0 > 8. < / RTI >

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