Heat radiation adhesive

Abstract

One embodiment of the present invention provides a heat dissipation adhesive comprising 83 to 85% alumina filler and 17 to 15% urethane resin, wherein the alumina filler comprises a first alumina having an average particle size of 45 μm, a second alumina having an average particle size of 10 μm, a third alumina having an average particle size of 2 μm, and a coating layer comprising silane coated on the surface of the first to third aluminas.

Description

Technology Field

[0001] The present invention relates to a heat-dissipating adhesive, and more specifically, to a heat-dissipating adhesive comprising a plurality of aluminas with different average particle sizes, a coating layer containing silane formed on the surface of each alumina, and the same mixed with a urethane resin. Background Technology

[0003] Recently, there has been a demand for thermal dissipation products with excellent heat dissipation characteristics not only in electronic devices but also in various other fields. Furthermore, as high-speed and integrated semiconductor devices become increasingly smaller, lighter, and thinner, their heat generation is increasing. Consequently, there is a need for thermal dissipation products with higher performance. Currently, thermal dissipation products are broadly classified into electrically conductive and non-electrically conductive types, primarily utilizing materials such as metals, ceramics, and thermal silicon. In the case of non-conductive thermal silicon, ceramic fillers are added to the resin; the ceramic materials mainly used are inorganic fillers such as silicon dioxide (SiO2), alumina (Al2O3), boron nitride (BN), and aluminum nitride (AlN), which are non-electrically conductive and possess excellent thermal conductivity. These fillers are applied according to specific uses and characteristics. However, there are various limitations in their use due to significant differences in thermal conductivity and price among these inorganic fillers. Silicon dioxide has the disadvantage of relatively low thermal conductivity despite its low cost, while boron nitride and aluminum nitride have high thermal conductivity but are considerably expensive. Therefore, alumina fillers, which have relatively higher thermal conductivity than silicon dioxide, are being widely adopted recently. However, alumina has a high inherent density, resulting in a larger mass for products containing such fillers, and its high hardness inevitably leads to equipment wear during the manufacturing process. Furthermore, to maximize thermal conductivity by increasing the filling rate, it is preferable to form the material into a spherical shape; however, while alumina and silicon dioxide can be manufactured in a spherical form, boron nitride and aluminum nitride are difficult to spherical, leading to a problem of reduced filling rate.

[0005] Prior Art: Korean Registered Patent No. 10-2534715

[0006] The prior art relates to 'organic-inorganic composite filler, a heat dissipating composition including the same, and a method for manufacturing an organic-inorganic composite filler,' and discloses an organic-inorganic composite filler comprising alumina, a first coating layer located on the surface of the alumina and comprising a polymer binder, and a second coating layer located on the first coating layer and comprising a thermally conductive ceramic compound including one or more selected from the group consisting of boron nitride (BN), aluminum nitride (AlN), silicon carbide (SiC), magnesium oxide (MgO), zinc oxide (ZnO), and aluminum hydroxide (Al(OH)3), and a heat dissipating material including the same. The problem to be solved

[0008] One embodiment of the present invention may provide a heat dissipation adhesive comprising a plurality of aluminas with different average particle sizes, a coating layer containing silane formed on the surface of each alumina, and the same mixed with urethane resin. means of solving the problem

[0010] One embodiment of the present invention provides a heat dissipation adhesive comprising 83 to 85% alumina filler and 17 to 15% urethane resin, wherein the alumina filler comprises a first alumina having an average particle size of 45 μm, a second alumina having an average particle size of 10 μm, a third alumina having an average particle size of 2 μm, and a coating layer comprising silane coated on the surface of the first to third aluminas.

[0011] The above coating layer may have an average thickness of 2㎛.

[0012] The above alumina filler may include 90% first alumina, 8% second alumina, and 2% third alumina.

[0013] The above urethane resin comprises a first composition in which PG and PPGDGE are mixed in a 1:1 equivalent ratio, and a second composition in which TDI and PPG are mixed in a 1:1 equivalent ratio, and the first composition and the second composition may be mixed in the same ratio. Effects of the invention

[0015] According to one embodiment of the present invention, a heat-dissipating adhesive can be obtained by forming a coating layer containing silane on the surface of each of aluminas with a plurality of aluminas having different average particle sizes and mixing the same with urethane resin. Brief explanation of the drawing

[0017] FIG. 1 is a diagram showing the adhesive density according to the ratio of alumina to silane in an alumina filler in a heat-dissipating adhesive according to one embodiment of the present invention. FIG. 2 is a graph comparing stress and deformation results according to the TDI ratio of the second composition in a heat dissipation adhesive according to the present embodiment. Specific details for implementing the invention

[0018] The present invention will be described in detail below with reference to the attached drawings.

[0020] A heat dissipation adhesive according to one embodiment of the present invention may comprise 83 to 85% of an alumina filler and 17 to 15% of a urethane resin. In this case, the alumina filler may comprise a first alumina with an average particle size of 45 μm, a second alumina with an average particle size of 10 μm, and a third alumina with an average particle size of 2 μm. Alumina possesses high thermal conductivity and electrical insulation properties, allowing it to effectively dissipate heat without electrical interference. In the heat dissipation adhesive according to this embodiment, three types of alumina with different average particle sizes may be used. By mixing aluminas with different average particle sizes, smaller particles can fill the voids between larger particles, thereby increasing density. Consequently, the contact area between particles increases, which can improve the heat transfer path. Furthermore, the presence of particles of various sizes allows for more efficient inter-particle arrangement, which can reduce contact resistance. This can improve the heat conduction path. In this embodiment, the alumina filler may comprise 90% of a first alumina, 8% of a second alumina, and 2% of a third alumina.

[0021] In the heat dissipation adhesive according to the present embodiment, a coating layer comprising silane may be included, which is coated on the surface of the first to third aluminas. When the surface of the first to third aluminas is coated with silane, the hydrophilicity or hydrophobicity of the surface can be controlled according to the functional groups of the silane. By controlling hydrophilicity or hydrophobicity, the surface energy can be controlled to improve adhesive performance. Furthermore, the silane coating acts on the surface of the alumina particles to prevent aggregation between particles and improve dispersibility. Through the silane coating, the alumina can be better dispersed in various solvents. Additionally, the functional groups of the silane can form chemical bonds with the alumina to strengthen adhesion. Through this, the strength of the heat dissipation adhesive can be improved. In the present embodiment, the coating layer may have an average thickness of 2 μm.

[0022] Urethane resins may be suitable for applications in thermal adhesives where mechanical flexibility and adhesion are critical. When combined with alumina fillers, these urethane resins can enhance thermal conductivity and aid in shock absorption and maintaining durability. Due to their higher flexibility compared to epoxy resins, urethane resins are suitable for bonding materials with different coefficients of thermal expansion. Furthermore, they can provide excellent adhesion performance to various substrates, such as metals, ceramics, and plastics, and maintain uniform dispersion by improving compatibility with alumina fillers.

[0023] In this embodiment, the urethane resin may comprise a first composition mixed with PG (Propylene Glycol) and PPGDGE (Polypropylene Glycol Diglycidyl Ether), and a second composition mixed with TDI (Toluene Diisocyanate) and PPG (Polypropylene Glycol). PG can be used as an auxiliary material in the manufacturing process of the urethane resin, acts as a polyhydric alcohol (polyol), participates in the formation of urethane bonds, and can improve processability by lowering the viscosity of the urethane resin. PPGDGE can be mainly used as an additive in the urethane resin. The epoxy functional groups of PPGDGE can participate in the curing reaction of the urethane resin to improve mechanical strength and heat resistance. The first composition, a mixture of PG and PPGDGE, can contribute to controlling the viscosity of urethane resin, providing flexibility, accelerating the curing reaction, and improving durability. When used in combination, they can help optimize the physical and chemical properties of urethane resin. TDI is a major isocyanate component used in the manufacture of polyurethane; it reacts with polyols to form urethane bonds (-NHCOO-), and this reaction forms the main framework of the urethane resin and can determine its physical properties. TDI can increase mechanical strength and chemical resistance by forming high-hardness polyurethane. PPG is a representative polyol used in urethane resins that can provide flexibility and durability. PPG reacts with TDI to form urethane bonds and can create a continuous polymer structure of polyurethane. Due to its high flexibility, PPG can enable polyurethane products to absorb shock and stress while maintaining durability.The isocyanate functional group of TDI and the hydroxyl functional group of PPG react to form urethane bonds, and these bonds form the main framework of the urethane resin and can determine the properties of the polyurethane after curing. The second composition, which is a mixture of TDI and PPG, is a key material for adjusting the performance of the urethane resin and can play an important role in various applications such as thermally conductive adhesives, coatings, and foams. In this embodiment, the urethane resin comprises a first composition in which PG and PPGDGE are mixed in a 1:1 equivalent ratio and a second composition in which TDI and PPG are mixed in a 1:1 equivalent ratio, and the first composition and the second composition may be mixed in the same ratio.

[0025] FIG. 1 is a diagram showing the adhesive density according to the ratio of alumina to silane in the alumina filler in a heat-dissipating adhesive according to one embodiment of the present invention. In this embodiment, the heat-dissipating adhesive may include an alumina filler comprising a first alumina with an average particle size of 45 μm, a second alumina with an average particle size of 10 μm, and a third alumina with an average particle size of 2 μm. A coating layer with an average thickness of 2 μm may be formed on the surface of each of the first alumina, the second alumina, and the third alumina. In this embodiment, the alumina filler may comprise 90% of the first alumina, 8% of the second alumina, and 2% of the third alumina. Referring to FIG. 1, it can be seen that a resin mixture of 83% alumina filler and 17% urethane resin records the highest density. This may be a result contributed by the high density characteristics of alumina and the stable bonding by the resin.

[0027] FIG. 2 is a graph comparing stress and deformation results according to the ratio of TDI in the second composition in the heat dissipation adhesive according to the present embodiment. In the present embodiment, the heat dissipation adhesive may include an alumina filler comprising a first alumina with an average particle size of 45 μm, a second alumina with an average particle size of 10 μm, and a third alumina with an average particle size of 2 μm. A coating layer with an average thickness of 2 μm may be formed on the surface of each of the first alumina, the second alumina, and the third alumina. Such an alumina filler may be mixed with a urethane resin comprising a first composition mixed with PG and PPGDGE and a second composition mixed with TDI and PPG. Looking at the stress and deformation results of the heat dissipation adhesive according to the ratio of TDI in the second composition in the present embodiment, the highest stress and stable deformation are observed when the TDI in the second composition is 83.9%. At this ratio, the water resistance of the heat-dissipating adhesive is most excellent, and structural stability can be ensured.

[0029] Although the present invention has been described above with reference to preferred embodiments and examples, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

Claim 1 A heat-dissipating adhesive comprising 83 to 85% alumina filler and 17 to 15% urethane resin, wherein the alumina filler comprises: a first alumina having an average particle size of 45 μm; a second alumina having an average particle size of 10 μm; a third alumina having an average particle size of 2 μm; and a coating layer coated on the surface of the first to third aluminas and comprising silane. Claim 2 A heat-dissipating adhesive according to claim 1, wherein the coating layer has an average thickness of 2㎛. Claim 3 A heat-dissipating adhesive according to claim 1, characterized in that the alumina filler comprises 90% first alumina, 8% second alumina, and 2% third alumina. Claim 4 A heat-dissipating adhesive according to claim 1, wherein the urethane resin comprises a first composition in which PG and PPGDGE are mixed in a 1:1 equivalent ratio; and a second composition in which TDI and PPG are mixed in a 1:1 equivalent ratio, and wherein the first composition and the second composition are mixed in the same ratio.

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