Spherical alumina powder, method for preparing the same, and use thereof

Abstract

The present disclosure provides a method for manufacturing spherical alumina powder, comprising the steps of: preparing alumina powder; sphericalizing the alumina powder; and collecting the sphericalized alumina powder; a spherical alumina powder manufactured by the method; and a product comprising the spherical alumina powder.

Description

Technology Field

[0001] The present disclosure relates to spherical alumina powder, a method for manufacturing the same, and a product comprising the same. Background Technology

[0002] As the portability and performance of electronic devices have recently been maximized, semiconductor packaging technology is rapidly evolving toward miniaturization, thinning, and high integration to maximize functionality while minimizing chip size. To accommodate more circuits and components within a limited space, the internal structure of the package is becoming more complex; consequently, thermal management issues and ensuring structural stability are emerging as critical challenges in the packaging process.

[0003] High Bandwidth Memory (HBM), a representative example of this high-density integration trend, features a structure that dramatically increases data processing speed by vertically stacking multiple memory dies. In stacked structures like HBM, it is essential not only to precisely fill the minute gaps between chips but also to apply high-performance encapsulant and underfill materials capable of rapidly dissipating heat generated within the stacked chips to the outside. Furthermore, in the case of GDDR (Graphics DDR), which is a high-performance 2D DRAM mounted planarly on a graphics card PCB, heat dissipation is essential to prevent performance degradation and ensure stability by dissipating the high heat generated during high-performance gaming or tasks.

[0004] As part of the thermal management solutions required for the aforementioned advanced packaging structures, the use of alumina (Al2O3) powder, which possesses both excellent electrical insulation and high thermal conductivity, is being considered. Alumina powder acts as a filler that forms heat dissipation pathways when mixed with organic resins; unlike metal-based heat dissipation materials, it poses no risk of electrical short circuits, making it known as a key material that provides effective cooling performance while maintaining the reliability of semiconductor devices.

[0005] In particular, as packages become thinner and circuits become more miniaturized, there is a growing need for materials with improved properties compared to conventional crushed alumina. Spherical alumina powder, with its controlled spherical particle shape, offers a small surface area that enables high filling rates within the resin and provides excellent fluidity during molding, allowing it to fill minute spaces without gaps. Furthermore, its high-purity characteristics, achieved through extreme impurity control, play a pivotal role in ensuring the long-term reliability of advanced semiconductor packages by preventing ionic contamination during microfabrication processes. Prior art literature

[0006] (Patent Document 0001) KR 10-2011-0115535 A The problem to be solved

[0007] According to one aspect of the present disclosure, a method for producing high-purity spherical alumina powder may be provided. According to another aspect, high-purity spherical alumina powder may be provided. According to yet another aspect, a product comprising said spherical alumina powder may be provided. means of solving the problem

[0008] One aspect of the present disclosure is a method for producing spherical alumina powder, comprising the steps of: preparing alumina powder; sphericalizing the alumina powder; and collecting the sphericalized alumina powder.

[0009] According to one embodiment, the step of preparing the alumina powder comprises: preparing aluminum hydroxide powder; acid-dissolving the aluminum hydroxide powder to produce an aluminum salt hydrate solution; contacting the aluminum salt hydrate solution with an acidic gas to precipitate aluminum salt crystals; purifying the aluminum salt crystals; and producing the alumina powder from the purified aluminum salt crystals.

[0010] According to one embodiment, the step of producing alumina powder from the purified aluminum salt crystal comprises: wet milling the purified aluminum salt crystal; drying the wet-milled aluminum salt crystal; heat-treating the dried aluminum salt crystal to produce alumina; and dry-milling the alumina to obtain alumina powder having a predetermined average particle size.

[0011] According to one embodiment, the spheroidization is performed by flame fusion, and the flame fusion uses a flame formed by the combustion of fuel gas and oxidizing gas.

[0012] According to one embodiment, the method further comprises the step of selecting powder having a predetermined particle size range from the collected spherical alumina powder; and the step of purifying the selected powder.

[0013] According to one embodiment, the screening step is performed by at least one of sieving and classification.

[0014] According to one embodiment, the purification step is performed by at least one of washing, wet sieving, and drying.

[0015] Another aspect of the present disclosure is spherical alumina powder, which is manufactured by the method described above and has an average particle size (D) of 1-70 μm. 50) having, and the above powder is 0.1-2.0 m 2 It satisfies at least one of a specific surface area of ​​ / g; a sphericity of 0.90 or more; and a uranium content of 5 ppb or less.

[0016] According to one embodiment, the powder has an average particle size (D) of 3-15 μm. 50 The powder has a maximum particle size (D100) of 20-50 μm; an ionic impurity content of 10 ppm or less; and an electrical conductivity of 10 μS / cm or less.

[0017] According to one embodiment, the spherical alumina powder has an average particle size (D) of 3-5 μm. 50 ) and maximum particle size of 20 μm or less (D 100 A first powder having ); an average particle size (D) of 8-15 μm 50 ) and maximum particle size of 45 μm or less (D 100 A second powder having ); an average particle size of 1-3 μm (D 50 ) and maximum particle size of 15 μm or less (D 100 A third powder having ) or a combination thereof.

[0018] According to one embodiment, the spherical alumina powder satisfies at least one of an ionic impurity content of 10 ppm or less; and an electrical conductivity of 10 μS / cm or less.

[0019] Another aspect of the present disclosure comprises the spherical alumina powder described above as a filler.

[0020] Another aspect of the present disclosure is a thermally conductive resin composition comprising the filler and resin described above.

[0021] Another aspect of the present disclosure is that an encapsulant is formed from the thermally conductive resin composition described above.

[0022] Another aspect of the present disclosure is that a device is encapsulated with the thermally conductive resin composition described above. Effects of the invention

[0023] High-purity spherical alumina powder can be produced through the method of the present disclosure. According to one embodiment, the powder may have a high degree of sphericity. According to one embodiment, the powder may have a strictly controlled uranium content. According to one embodiment, the powder may have a low impurity content and low electrical conductivity.

[0024] The method of the present disclosure has excellent economic efficiency in terms of energy and cost consumed in the production of spherical alumina powder, and can provide excellent yield and supply stability in terms of powder production efficiency.

[0025] The spherical alumina powder of the present disclosure may be included in a filler, said filler may be included in a thermally conductive resin composition, and said composition may be cured to form an encapsulant. The present disclosure may provide an element encapsulanted by said thermally conductive resin composition or encapsulant. Specific details for implementing the invention

[0026] The present disclosure will be described in detail below. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described illustratively.

[0028] Method for manufacturing spherical alumina powder

[0029] One aspect of the present disclosure provides a method for manufacturing spherical alumina powder. The spherical alumina powder is a high-purity spherical alumina powder having low radioactivity and excellent sphericity, and can be utilized in various fields. For example, the high-purity spherical alumina powder of the present disclosure can be used in the field of high-bandwidth memory packaging, specifically as a thermal filler in an EMC (Epoxy Molding Compound) composition that seals and protects a semiconductor chip. Unlike conventional semiconductor components, HBMs have high power density, so soft errors caused by alpha rays generated from uranium present in the alumina powder are prone to occur, and to prevent such soft errors, it is required to control the uranium content in the alumina powder. Furthermore, in the recent packaging field, in order to further improve the thermal performance of the alumina powder in line with the technology trends of miniaturization, thin films, and high integration, a high filling rate and excellent gap filling capability of the alumina powder are required. To satisfy this, the present disclosure provides a manufacturing method that can easily control the particle size distribution of spherical alumina powder and improve the degree of sphericity of spherical alumina powder.

[0030] The above method includes the steps of: preparing alumina powder; sphericalizing the alumina powder; and collecting the sphericalized alumina powder.

[0031] In order to produce spherical alumina powder in the present disclosure, non-spherical alumina powder is first prepared. The alumina powder is a high-purity alumina powder and may have a uranium content of 5 ppb or less. The alumina powder may also have a trace amount of other impurities (less than 200 ppm), and specifically, may not substantially contain other impurities. By using such high-purity alumina powder, the method of the present disclosure enables the omission of an additional uranium reduction step in the subsequent spherical alumina powder manufacturing process, and enables stable particle size control and high sphericity.

[0032] According to one embodiment, the alumina powder is 0.2-2.5 m 2 It can have a specific surface area of ​​ / g. The above specific surface area is 0.2 m 2 If it is less than / g, the content of granular powder in the spherical alumina powder manufactured using it increases, which may cause problems that adversely affect the gap-filling characteristics of the final product. On the other hand, the above specific surface area is 2.5 m² 2 If it exceeds / g, a problem may occur where the powders adsorb to each other during the spheroidization step described later. This can result in a decrease in the degree of sphericity of the final product and non-uniform particle size.

[0033] Also, according to one embodiment, the alumina powder has an average particle size (D) of 1-70 μm. 50It may have an average particle size. If the average particle size is less than 1 μm, a problem may arise where it becomes difficult to supply uniform powder within the melting furnace. On the other hand, if the average particle size exceeds 70 μm, a problem may arise where the yield of the final product decreases in terms of controlling the maximum particle size of the final product. According to another embodiment, the alumina powder may have an average particle size corresponding to the spherical alumina powder, which is the final product. For example, corresponding to each of the first to third spherical alumina powders described below, the average particle size (D 50 First non-spherical alumina powder having a diameter of 3-5 μm; average particle size (D 50 Second non-spherical alumina powder having a diameter of 8-15 μm; average particle size (D 50 A third non-spherical alumina powder having a thickness of 1-3 μm, or a combination thereof, may be prepared.

[0034] To prepare non-spherical alumina powder as described above, the present disclosure also provides a specific preparation method. According to one embodiment, the step of preparing the alumina powder may include: preparing aluminum hydroxide powder; dissolving the aluminum hydroxide powder in an acid to produce an aluminum salt hydrate solution; contacting the aluminum salt hydrate solution with an acidic gas to precipitate aluminum salt crystals; purifying the aluminum salt crystals; and producing alumina powder from the purified aluminum salt crystals.

[0035] First, the step of preparing the alumina powder may include the step of preparing aluminum hydroxide powder. Aluminum hydroxide powder is available through known means, and commercially available aluminum hydroxide powder may also be used. According to one embodiment, the aluminum hydroxide powder may have an Al(OH)3 purity of 99.5% or higher. The aluminum hydroxide powder may contain less than 100 ppm of iron, less than 200 ppm of sodium, and less than 100 ppm of silicon. If the content of impurities exceeds the values ​​described above, a problem may arise in which the reliability of the final product is reduced.

[0036] The aluminum hydroxide powder is mixed with an acid solution. As a result of the mixing, an aluminum salt hydrate solution is produced. Accordingly, the alumina powder preparation step may include the step of dissolving the aluminum hydroxide powder in an acid to produce an aluminum salt hydrate solution. Through the acid dissolution, insoluble impurities present in the aluminum hydroxide powder can be primarily removed.

[0037] For the above acid dissolution, various acid solutions may be used. According to one embodiment, the acid used for the acid dissolution may be hydrochloric acid. The use of hydrochloric acid can contribute to obtaining high-purity alumina and has the advantage of easily volatilizing upon heating, leaving no residue on the alumina, and also being easy to collect and reuse the volatilized hydrochloric acid. When hydrochloric acid is used for acid dissolution, the resulting aluminum salt hydrate solution may be referred to as an aluminum chloride hydrate solution.

[0038] The above acid dissolution can be performed under known acid dissolution conditions and is not particularly limited. For example, the above acid dissolution may include the step of acid leaching the aluminum hydroxide powder in a 30% hydrochloric acid solution.

[0039] After the above acid dissolution, insoluble impurities may exist in solid form within the solution, and a step of filtering the impurities may be required to remove them from the solution. Accordingly, according to one embodiment, the step of acid-dissolving aluminum hydroxide powder to produce an aluminum salt hydrate solution may further include a step of filtering insoluble impurities from the aluminum salt hydrate solution. The filtration means is not particularly limited and may be performed using known solid-liquid separation means.

[0040] The aluminum salt hydrate solution may contain other impurities in addition to the alumina component present in the aluminum hydroxide powder. In order to separate the alumina component from these impurities and uranium, a process of contacting the solution with an acidic gas may be subsequently performed. In other words, the alumina powder preparation step may include a step of contacting the aluminum salt hydrate solution with an acidic gas to precipitate the aluminum salt hydrate. The aluminum salt hydrate in the solution is converted into a solid state upon contact with the acidic gas and forms a precipitate. At this time, since uranium or other impurities are still dissolved in the solution, the purity of the alumina component can be significantly increased through this step.

[0041] According to one embodiment, the acidic gas may be hydrogen chloride gas. Specifically, the acidic gas may be anhydrous hydrogen chloride gas. In particular, in some embodiments where hydrochloric acid is used for acid dissolution, the aluminum chloride hydrate solution may come into contact with anhydrous hydrogen chloride gas to form aluminum chloride crystals. Although not wishing to be bound by a specific theory, it is thought that when hydrogen chloride gas is supplied to the hydrate solution and the concentration of hydrogen chloride in the solution increases, the solubility of the aluminum component decreases rapidly due to the common-ion effect, thereby forming aluminum chloride crystals. Furthermore, it is thought that other metal impurities remain in the solution by forming water-soluble complex ions in such a high-concentration hydrogen chloride environment.

[0042] In terms of improving the efficiency of crystal formation as described above, the contact may be performed by sparging an acidic gas into an aluminum salt hydrate solution. The sparging may be performed under known conditions and is not particularly limited.

[0043] Through the above contact step, uranium within the aluminum salt crystal can be significantly reduced, and additionally, impurities or Na + Ionic impurities such as [such as] can also be significantly reduced. The aluminum salt crystals obtained through contact with an acidic gas are subsequently separated from the solution and purified. In other words, the alumina powder preparation step may include a step of purifying the aluminum salt crystals.

[0044] Through the purification step described above, aluminum salt crystals are separated from the solution, and impurities such as uranium that may be attached to the surface of the crystals are removed, thereby further improving the purity of the aluminum component. Specifically, the purification step may further include a step of filtering aluminum salt crystals precipitated from an aluminum salt hydrate solution in contact with an acidic gas; and a step of acid-washing the filtered aluminum salt crystals. The filtration means is not particularly limited and can be performed using known solid-liquid separation means. Meanwhile, the acid used for acid-washing may be hydrochloric acid. The acid-washing can also contribute to controlling the specific surface area of ​​the crystal particles in conjunction with the wet milling described later.

[0045] As described above, alumina powder is produced using purified aluminum salt crystals. Accordingly, the alumina powder preparation step may include a step of producing alumina powder from the purified aluminum salt crystals. Specifically, the alumina powder production step may include a step of wet-milling the purified aluminum salt crystals; a step of drying the wet-milled aluminum salt crystals; a step of heat-treating the dried aluminum salt crystals to produce alumina; and a step of dry-milling the alumina to obtain alumina powder having a predetermined average particle size.

[0046] The purified aluminum salt crystals can be controlled through wet milling so that the crystal particles have a predetermined particle size distribution and specific surface area. Wet milling may be preferable to dry milling in terms of inhibiting particle re-aggregation and forming a uniform particle size distribution. The wet milling can be performed under known conditions and is not particularly limited.

[0047] Subsequently, solvents present on the surface of the aluminum salt crystal after wet milling can be removed through drying. The drying may include spray drying or hot air drying. The drying may be performed at a temperature in the range of 100-200°C.

[0048] Dried aluminum salt crystals can be converted into alumina through a heat treatment step. The heat treatment step may include a calcination step of the dried aluminum salt crystals. Through calcination, crystal water is removed and a phase transition occurs. The resulting alumina maintains substantially the same size as the aluminum salt crystals prior to conversion.

[0049] The above heat treatment step can be performed at a temperature in the range of 1,000-1,400℃. Accordingly, the aluminum salt crystal can be converted into alumina, specifically alpha alumina.

[0050] The alumina produced in this way can be milled through dry milling into alumina powder having an average particle size corresponding to the average particle size of the spherical alumina powder to be finally produced. The dry milling can be performed under known conditions and is not particularly limited.

[0051] Non-spherical alumina powder can be prepared through the method described above. The method of the present disclosure produces high-purity spherical alumina powder by introducing the non-spherical alumina powder into the spherification step described below. Since the method performs an acid treatment process prior to spherification, it has the advantage of not requiring consideration of maintaining the spherical shape of the alumina powder due to the acid treatment. As a result, compared to a method that performs acid treatment after spherification, the uranium content can be easily reduced, and consequently, higher purity can be easily achieved. Furthermore, a high degree of sphericity of the final product can also be achieved.

[0052] Furthermore, the method of the present disclosure is characterized by manufacturing spherical alumina powder using non-spherical alumina powder. In the case of conventional technology that manufactures spherical alumina directly from aluminum hydroxide using a melting method, there is a disadvantage in that the endothermic reaction caused by the release of crystal water contained in the aluminum hydroxide during melting lowers the flame temperature, resulting in uneven particle size and reduced yield and sphericity. Additionally, there is a disadvantage in that it is difficult to control particle growth due to changes in the crystal phase occurring during high-temperature calcination. Furthermore, there is a disadvantage in that additional energy consumption costs are incurred due to the aforementioned endothermic reaction. The method of the present disclosure makes it possible to avoid the disadvantages of the conventional technology described above by using the step of preparing non-spherical alumina powder as described above.

[0053] The above method includes the step of sphericalizing the non-spherical alumina powder. As described above, by manufacturing spherical alumina powder using high-purity alumina powder with controlled specific surface area and controlled uranium content, the particle size distribution of the spherical alumina powder can be controlled more precisely, the maximum particle size can be easily controlled to a desired range, and a high degree of sphericity of the alumina powder can also be achieved.

[0054] According to one embodiment, the spheroidization can be performed by flame fusion. Without being bound by any specific theory, non-spherical alumina powder is introduced into a high-temperature flame, and the flame causes instantaneous heat transfer from the surface to the center of the alumina particles, converting them into a droplet state. Surface tension acts on the alumina in the droplet state, causing it to transform into a spherical shape that minimizes surface area in order to minimize energy. The particles passing through the flame are rapidly cooled and converted into solid crystals while maintaining their spherical shape.

[0055] There exists a conventional technology for manufacturing spherical alumina powder from aluminum metal using Vaporized Metal Combustion (VMC). This technology has disadvantages, such as the requirement for expensive equipment like a plasma torch, and the potential for metal impurities, such as iron, to be included in the final product during the vaporized combustion process, thereby affecting the reliability of the final product. Furthermore, the conventional technology suffers from the problem that some of the starting material, aluminum metal, remains unconverted into spherical alumina and acts as an impurity, degrading insulation properties. The method disclosed in this invention manufactures spherical alumina powder from non-spherical alumina powder using flame spraying, thereby avoiding the disadvantages and problems associated with the aforementioned conventional technology.

[0056] The flame spraying described above uses a flame formed by the combustion of a fuel gas and an oxidizing gas. The fuel gas refers to the substance combusted in the combustion reaction and serves to generate high-temperature thermal energy. The flame must have a temperature of 2,050°C or higher, which is the melting point of alumina, in order to melt the alumina powder. To this end, for example, the fuel gas may include LPG, LNG, propane, butane, acetylene, hydrogen, or a combination thereof. Specifically, the fuel gas may include LPG. More specifically, the fuel gas may be LPG.

[0057] Meanwhile, the oxidizing gas is a gas that promotes the combustion of the fuel gas. The oxidizing gas may include oxygen or air. Specifically, to obtain a high-temperature flame capable of melting alumina, the oxidizing gas may be oxygen.

[0058] A flame is formed by the combustion of the fuel gas and oxidizing gas described above. The temperature of the flame is not particularly limited as long as it is a temperature capable of melting the alumina powder. For example, the temperature of the flame may be about 2,000-4,000°C, specifically 2,000-3,000°C.

[0059] The above method includes the step of collecting spherical alumina powder. The spherical alumina powder is collected for recovery or introduction into a subsequent process. The means for collecting is not particularly limited, and known means for collecting may be used. For example, a cyclone separator may be used as the means for collecting.

[0060] In addition, the specific surface area of ​​the captured spherical alumina powder is 0.1-2.0 m² 2 It can be / g. Compared to the specific surface area of ​​the non-spherical alumina powder described above, the specific surface area of ​​the spherical alumina powder is smaller, and this decrease in specific surface area can also be understood as indicating that the alumina powder has achieved a high degree of sphericity.

[0061] To improve the yield of spherical alumina powder having a target average particle size from the above-mentioned spherical alumina powder, the captured spherical alumina powder may be introduced into an additional process. According to one embodiment, the method may further include a step of selecting powder having a predetermined particle size range from the captured alumina powder. The selection step may be performed by at least one of sieving and classification.

[0062] Sieving is a method of filtering particles by size using a physical mesh. Specifically, the sieving performed in the screening step may be dry sieving. The sieving may be used for the purpose of removing large particles. For example, during the process of converting aluminum hydroxide into alumina, aggregation of crystals may occur, and such aggregates may correspond to the large particles. Since spherical alumina powder can be used for HBM packaging as a final product, sieving can control the maximum particle size of the alumina powder so that particles larger than the gap between HBM chips are not included in the final product. For example, the mesh size of the sieve can be controlled so that the maximum particle size (D100) of the spherical alumina is 50 μm or less, 20 μm or less, or 10 μm or less. If necessary, sieving may be performed using multiple sieves with different mesh sizes.

[0063] Classification is a method of separating fine particles by size using airflow and centrifugal force. For example, classification can be performed using a high-speed rotating rotor and airflow. Large particles are flung outward by centrifugal force, while small particles gather inward along the airflow and can be separated. The above classification can be used for the purpose of removing coarse particles and controlling fine particles. Since particles with a large specific surface area of ​​less than 1 μm can excessively increase the viscosity of EMC when mixed with epoxy resin in packaging such as HBM and GDDR, the flowability of EMC can be improved by removing these fine particles. For example, the above classification is the average particle size (D) of spherical alumina 50 ) can be performed so that it becomes 3-5 μm or 8-15 μm.

[0064] According to some embodiments, the screening step may be performed by both sieving and classification. For example, powders screened by the screening step using a combination of first non-spherical alumina powder to third non-spherical alumina powder as a starting material may include first spherical alumina powder, second spherical alumina powder, third spherical alumina powder, or a combination thereof. Here, the first spherical alumina powder has an average particle size (D 50 ) is 3-5 µm, maximum particle size (D 100 ) may be 20 μm or less. The above second spherical alumina powder has an average particle size (D 50 ) is 8-15 µm, maximum particle size (D 100 ) may be 45 μm or less. The above third spherical alumina powder has an average particle size (D 50 ) is 1-3 µm, maximum particle size (D 100 ) may be 15 μm or less. For example, spherical alumina powder used in packaging such as HBM and GDDR may comprise only one of the first powder; the second powder; and the third powder. Additionally, spherical alumina powder used in packaging such as HBM and GDDR may be any combination comprising at least two of the first powder, the second powder, and the third powder. According to one embodiment, each of the first to third powders may have a sieve residue of 1,000 ppm or less.

[0065] The above method may further include a step of purifying the selected alumina powder. The purification step may be performed by at least one of washing, wet sieving, and drying. Specifically, the purification step may be performed by at least one of washing and wet sieving and drying. More specifically, the purification step may be performed by washing, wet sieving, and drying.

[0066] Through the above washing, impurities such as carbides and iron particles can be removed. Known washing means may be used. For example, washing may be performed using DI water. The washing may be performed in a temperature range of about 50-100°C.

[0067] Wet control may be performed to prevent powder accumulation and sieve clogging, and to control the particle size of the alumina powder more precisely. The wet control may be performed in a known manner, for example, room temperature DI water may be used as the medium.

[0068] After the above wet sieving, drying may be performed to remove the medium present in the alumina powder. The drying may be, for example, hot air drying. The drying may be performed at a temperature sufficient to evaporate the medium. For example, if DI water is used as the medium, the drying may be performed in a temperature range of about 100-150°C.

[0069] Through the above screening and purification steps, high-purity spherical alumina powder with a desired particle size range and controlled specific surface area can be obtained. It is expected that the high-purity spherical alumina powder can be applied in various ways as a filler used in the packaging of electronic devices such as HBM and GDDR.

[0071] Spherical alumina powder

[0072] Another aspect of the present disclosure provides spherical alumina powder produced by the manufacturing method described above. According to some embodiments, the spherical alumina powder has an average particle size (D) of 1-70 μm. 50 It may have ). The spherical alumina powder is 0.1-2.0 m 2 It can satisfy at least one of a specific surface area of ​​ / g; a degree of sphericity of 0.90 or more; and a uranium content of 5 ppb or less. Specifically, the spherical alumina powder is 0.1-2.0 m2 It can satisfy at least two of a specific surface area of ​​ / g; a degree of sphericity of 0.90 or more; and a uranium content of 5 ppb or less. More specifically, the spherical alumina powder is 0.1-2.0 m 2 It can satisfy all of the following: a specific surface area of ​​ / g; a sphericity of 0.90 or more; and a uranium content of 5 ppb or less.

[0073] According to another embodiment, the spherical alumina powder may comprise a first powder; a second powder; a third powder; or a combination thereof. The first powder has an average particle size (D) of 3-5 μm. 50 ) and maximum particle size of 20 μm or less (D 100 ) may have. The second powder has an average particle size (D) of 8-15 μm. 50 ) and maximum particle size of 45 μm or less (D 100 ) may have. The third powder has an average particle size (D) of 1-3 μm. 50 ) and maximum particle size of 15 μm or less (D 100 Each of the first to third powders may have at least one of the specific surface area, degree of sphericity, and uranium content described in the previous paragraph. Specifically, each of the first to third powders may satisfy all of the specific surface area, degree of sphericity, and uranium content described above.

[0074] In some embodiments of the spherical alumina powder, the powder may satisfy at least one of an ionic impurity content of 10 ppm or less; and an electrical conductivity of 10 μS / cm or less. Specifically, the powder may satisfy both an ionic impurity content of 10 ppm or less and an electrical conductivity of 10 μS / cm or less. The ionic impurity is Na + , Cl - It may mainly contain. Additionally, the above ionic impurities are NH4 + , K + , Ca 2+ , SO4 2-It may include, but is not limited to, the following. If the content of ionic impurities in the spherical alumina powder exceeds the range described above, problems such as reduced insulation performance and poor reliability in high temperature and high humidity may occur in the final product.

[0075] The spherical alumina powder of the present disclosure can achieve the following advantages:

[0076] - By achieving a low uranium content, the possibility of soft errors can be reduced.

[0077] - By achieving a low specific surface area, problems such as increased viscosity, reduced fluidity, and increased moisture absorption can be prevented.

[0078] - By satisfying an average particle size within a specified range, problems such as increased viscosity, reduced fluidity and filling ability can be prevented, and also problems such as reduced gap filling characteristics in thin film package structures can be prevented.

[0079] - By satisfying the maximum particle size within a specified range, gap filling defects can be prevented.

[0080] - By achieving excellent sphericity, problems such as reduced flowability and gate blockage can be prevented.

[0081] - By achieving a low ionic impurity content, the problem of long-term reliability degradation under high temperature and high humidity environments can be prevented.

[0082] - By achieving low electrical conductivity, problems such as long-term reliability degradation and device power failure under high temperature and high humidity environments can be prevented.

[0083] The spherical alumina powder of the present disclosure, having the advantages described above, is expected to be effectively used as a filler in the packaging field.

[0085] Products containing spherical alumina powder

[0086] Another aspect of the present disclosure provides various products comprising the spherical alumina powder described above. First, a filler comprising spherical alumina powder may be provided. The filler refers to a filler material added to a resin or various matrix materials to complement physical properties such as thermal conductivity, insulation, and mechanical strength. In particular, the filler comprising spherical alumina powder of the present disclosure can serve to form an efficient heat transfer path by being uniformly dispersed within the material.

[0087] In addition to spherical alumina powder, the above filler may also include various other components depending on the desired physical properties. For example, the above filler may include at least one of spherical silica, boron nitride, and aluminum nitride. In the case of spherical silica, the coefficient of thermal expansion (CTE) of the composition can be lowered and low dielectric properties can be imparted. Boron nitride or aluminum nitride possesses excellent thermal conductivity and can be selectively used in locations where ultra-high heat dissipation properties are required.

[0088] According to one embodiment, the content of spherical alumina powder in the filler may be at least 50 wt%. Specifically, the content of spherical alumina powder in the filler may be 50-100 wt%, more specifically 50 wt% or more and less than 100 wt%, and even more specifically 50-99 wt%.

[0089] The present disclosure may also provide a thermally conductive resin composition comprising the spherical alumina powder. Specifically, the thermally conductive resin composition may include the filler and resin described above. The thermally conductive resin composition refers to a functional material formed by filling the filler described above at high density within a resin corresponding to a polymer matrix. The composition is utilized as a raw material for a heat dissipation component to efficiently release heat generated from an electrical / electronic device to the outside, and may be provided in various forms such as a paste, film, sheet, or molding compound depending on the usage environment. According to one embodiment, the composition may comprise 60-90 wt% of a filler and 3-20 wt% of a resin.

[0090] The resin of the above thermally conductive resin composition acts as a binder that binds the fillers together and forms a molded body. The types of resins available for use in the present disclosure are not particularly limited, and thermosetting resins may be used as examples. Specifically, the thermosetting resin may include epoxy resin, silicone resin, polyimide resin, polyurethane resin, and acrylic resin. According to one embodiment, the resin may be an epoxy resin.

[0091] The above thermally conductive resin composition may further include other components in addition to the filler and resin described above. Specifically, the above thermally conductive resin composition may further include a curing agent and a curing accelerator. Each of the curing agent and the curing accelerator can induce curing of the composition and control the reaction rate. According to one embodiment, the composition may include 1-10 wt% of a curing agent and 0.01-1 wt% of a curing accelerator. The types of the curing agent and the curing accelerator are not particularly limited, and known curing agents and curing accelerators may be used.

[0092] Additionally, the thermally conductive resin composition may further include other additives as needed. The other additives may include, but are not limited to, silane coupling agents, stress relievers, flame retardants, release agents, etc. According to one embodiment, the composition may include more than 0 and less than or equal to 10 wt% of other additives.

[0093] The method for manufacturing the above thermally conductive resin composition is not particularly limited and, as an example, can be carried out through a known melt mixing process.

[0094] The present disclosure may also provide an encapsulant comprising the spherical alumina powder. Specifically, the encapsulant may be formed from the composition described above. According to one embodiment, the encapsulant may be a semiconductor encapsulant for protecting a semiconductor device from external moisture, shock, and contamination, while simultaneously effectively dissipating heat generated during device operation.

[0095] Specifically, the above-described encapsulant can be obtained from the composition described above and has the advantages of high thermal conductivity, low radiation, low thermal expansion, high durability, and excellent moldability. In particular, since the above-described encapsulant includes the spherical alumina powder of the present disclosure, it has excellent thermal conductivity and gap-filling characteristics and can efficiently dissipate heat generated in a semiconductor device, making it highly suitable as an encapsulant for semiconductors.

[0096] The method of sealing a semiconductor device using the above thermally conductive resin composition is not particularly limited, and known methods such as compression, transfer molding, injection molding, and casting may be applied.

[0097] In addition, the above-mentioned packaging material can be obtained by curing the above-mentioned composition, and the heating temperature for curing is not particularly limited but may be about 150-250°C and the heating time may be about 1-10 hours.

[0098] The present disclosure may also provide a device comprising the spherical alumina powder. Specifically, the present disclosure may provide a device encapsulated with the thermally conductive resin composition described above. In other words, the device may be a device encapsulated with the encapsulating material described above. According to one embodiment, the device may be a semiconductor device. The semiconductor device may include, for example, GDDR, HBM memory devices, high-density system LSI devices, etc., but is not limited thereto.

[0100] In the following, embodiments of the present invention are further described with reference to specific experimental examples. The embodiments and comparative examples included in the experimental examples are merely illustrative of the present invention and are not intended to limit the appended claims. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and spirit of the present invention, and that such variations and modifications fall within the scope of the appended claims.

[0102] Examples

[0103] 1. Method for analyzing powder characteristics

[0104] (1) Particle size distribution D50, D100

[0105] Particle size was measured using a laser scattering particle size distribution analyzer (Malvern, 'CILAS1090L'). The powder to be measured was added to a distilled water dispersion medium at a measurable concentration, and then the sample was irradiated with ultrasound for 1 minute to perform the measurement.

[0107] (2) Specific surface area

[0108] The specific surface area was measured by the nitrogen adsorption method using Micrometrics' ASAP 2010.

[0110] (3) Sphericity

[0111] Measurements were taken using the Particle Image Analyzer CAMSIZER X2 manufactured by Microtrac.

[0113] (4) Ionic impurity content

[0114] 70g of DI water was added to 10g of alumina powder, and the mixture was eluted in an oven at 105°C for 12 hours. Afterward, the solution was cooled to room temperature, and the supernatant obtained by separating the solid and liquid phases by centrifugation was collected and measured using ion chromatography.

[0116] (5) Electrical conductivity

[0117] 100g of DI water was added to 10g of alumina powder, and ultrasonic treatment was performed for 10 minutes. Afterward, the supernatant was taken at room temperature for 1 hour and measured using an electrical conductivity measuring device.

[0119] (6) Uranium content

[0120] The uranium and thorium content of the alumina powder was measured as follows. First, the alumina powder was placed into a mixed aqueous solution of sulfuric acid and phosphoric acid and heated to dissolve the alumina powder, thereby preparing an aqueous solution. Subsequently, the aqueous solution was brought into contact with a cyclohexane solution of tributyl phosphate, which is commonly used as a uranium extractant, to extract the uranium contained in the solution. Then, the uranium transferred to the aqueous phase by back-extraction through contact with pure water was measured using ICP-MS based on the intensity of U238amu and Th232amu. Additionally, a 100 ppb standard solution was used to construct the calibration curve.

[0122] (7) Residuals

[0123] Alumina powder was added to distilled water, filtered through a sieve after 10 minutes, and the remaining powder was dried at 105°C to calculate the percentage of the remaining amount relative to the sample weight.

[0125] (8) Viscosity of the resin composition

[0126] A resin composition for viscosity measurement was prepared as follows. Alumina powder and bisphenol A type epoxy resin (viscosity 1800 cps) were weighed in a mass ratio of 8:2, and mixed and kneaded using a Thinky Mixer (ARE310) to prepare a resin composition for viscosity measurement. Subsequently, measurements were taken using an Anton Paar MCR302 with a diameter 25 mm parallel plate at a gap of 0.5 mm and a shear rate of 10 / s.

[0128] 2. Non-spherical alumina powder

[0129] (1) Preparation of non-spherical alumina powder

[0130] Aluminum hydroxide powder (99.8% purity) was acid-leached with a 30% hydrochloric acid solution, and then anhydrous hydrogen chloride gas was sparged into the solution to obtain aluminum salt crystals. The crystals were acid-washed with hydrochloric acid and then wet-milled. DI water was used as the medium. Subsequently, the crystals were dried in an oven at 150°C for 2 hours. Then, the oven temperature was adjusted to 1200°C and the crystals were calcined for 12 hours to obtain alumina. The obtained alumina was designated as Sample 4.

[0131] The above sample 4 was milled using a jet mill grinder with target average particle sizes set to approximately 3 μm, 5 μm, and 13 μm to obtain non-spherical alumina powder, and each of these was designated as samples 1-3.

[0132] As samples 5 and 6, commercially available non-spherical alumina powder was prepared.

[0134] (2) Characterization of non-spherical alumina powder

[0135] The results of the analysis of the particle size, specific surface area, and uranium content of each of the previously prepared samples 1-6 are shown in Table 1 below.

[0136] Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Particle size D50 (㎛) 12.5 4.5 2.5 55 16 3 Particle size D100 (㎛) 71 36 12 180 56 23 Specific surface area (m²) 2 / g) 1.00 1.21 1.30 0.8 120 7.9 Uranium content (ppb) 3.3 3.9 3.5 1.3 4.2 0.9

[0138] Referring to Table 1 above, it can be seen that, unlike samples 1 to 4 prepared through the method of the present disclosure, samples 5 and 6 have a large specific surface area despite their low uranium content. This implies that the alumina powder of samples 5 and 6 has high porosity, and it is expected that it will be difficult to input raw materials for the production of spherical alumina powder and also difficult to achieve the level of sphericity intended to be achieved in the present disclosure.

[0140] 3. Spherical alumina powder

[0141] (1) Preparation of spherical alumina powder

[0142] 33 Nm of LPG as fuel gas 3 / hr, 108 Nm of oxygen (O2) as an oxidizing gas 3 / hr, 57 Nm of oxygen (O2) as a powder carrier 3 A flame was formed under melting conditions using 1 / hr, and the non-spherical alumina powder of Sample 1 was injected into the flame zone at a rate of approximately 30-50 kg / hr to melt and spheroidize it. At this time, the amount of powder injected into the flame zone was adjusted to maintain a P / V (amount of powder / amount of fuel gas) of 0.9-1.5. Subsequently, the spheroidized powder was collected by sequentially passing through a cyclone and a bag filter. The collected powder was sieved using a 25 mesh sieve, washed by stirring with DI water at approximately 80°C for approximately 8 hours, and then dried at a temperature of approximately 120°C for approximately 20 hours after wet sieving. The spherical alumina powder obtained in this way was designated as Example 1.

[0143] Example 2 was prepared in the same manner as Example 1, except that Sample 2 was used instead of Sample 1, and after sieving, an additional classification process was performed using a classifier from Hosakawa.

[0144] Example 3 was prepared in the same manner as Example 2, except that Sample 3 was used instead of Sample 2.

[0145] Comparative Example 1 was prepared in the same manner as Example 1, except that Sample 4 was used instead of Sample 1 and an 80 mesh sieve was used.

[0146] Comparative Examples 2 and 3 were prepared in the same manner as Example 1, except that samples 5 and 6 were used instead of sample 1, respectively, and a 100 mesh sieve was used.

[0148] (2) Characterization of spherical alumina powder

[0149] The characteristics of each of the previously manufactured Examples 1-3 and Comparative Examples 1-3 were analyzed, and the results are shown in Table 2 below.

[0150] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Particle size D50 (㎛) 13.5 4.8 2.8 58 22 6.8 Particle size D100 (㎛) 43 18 8 120 85 45 Specific surface area (m²) 2 / g) 0.80 1.00 1.05 0.65 105 6.28 Sphericity 0.952 0.933 0.931 0.947 0.575 0.622 Ionic impurity content (Na+, ppm) 3.5 6.2 7.5 1.5 8.0 0.3 Electrical conductivity (uS / cm) 4.8 5.9 3.1 5.0 5.3 6.9 Uranium content (ppb) 3.8 4.5 4.1 1.5 5.0 1.1 Sieve Residue (ppm)_20um N / A 100 0 N / A N / A 40000 Sieve (ppm)_45um 80 N / A N / A 730000 110000 N / A Resin composition viscosity (Pa.s) 294 322 358 271 Unmeasurable 981

[0152] Referring to Table 2 above, it can be seen that Examples 1 to 3 satisfy the maximum particle size described above, while also satisfying high sphericity of 0.90 or higher, low ionic impurity content and uranium content, and low electrical conductivity.

[0153] In the case of Comparative Example 1, it can be seen that it has a significant sieve residue. Also, in the case of Comparative Example 2, it can be seen that it has a relatively high average particle size, a significant sieve residue, a low degree of sphericity, and a high specific surface area. Also, in the case of Comparative Example 3, it can be seen that it has a higher average particle size compared to Example 2, and also has a significant sieve residue, a low degree of sphericity, a high specific surface area, and a high viscosity of the resin composition.

[0155] The above description is merely an example of applying the principles of the present disclosure, and other configurations may be included without departing from the scope of the present invention.

Claims

Claim 1 A method for manufacturing spherical alumina powder having a specific surface area of ​​0.2-2.5 m² 2 A method for producing spherical alumina powder, comprising the step of preparing alumina powder with a weight of 1 / g, wherein the step of preparing the alumina powder comprises: the step of preparing aluminum hydroxide powder; the step of acid-dissolving the aluminum hydroxide powder to produce an aluminum salt hydrate solution; the step of contacting the aluminum salt hydrate solution with an acidic gas to precipitate aluminum salt crystals; the step of purifying the aluminum salt crystals; and the step of producing alumina powder from the purified aluminum salt crystals, wherein the step of producing alumina powder from the purified aluminum salt crystals comprises: the step of wet-milling the purified aluminum salt crystals; the step of drying the wet-milled aluminum salt crystals; the step of heat-treating the dried aluminum salt crystals to produce alumina; and the step of dry-milling the alumina to obtain alumina powder having a predetermined average particle size; the step of sphericalizing the alumina powder; and the step of collecting the sphericalized alumina powder. Claim 2 A method for producing spherical alumina powder according to claim 1, wherein the spherification is performed by flame fusion, and the flame fusion uses a flame formed by the combustion of fuel gas and oxidizing gas. Claim 3 A method for producing spherical alumina powder according to claim 1, wherein the method further comprises the step of selecting powder having a predetermined particle size range from the collected spherical alumina powder; and the step of purifying the selected powder. Claim 4 A method for producing spherical alumina powder according to claim 3, wherein the screening step is performed by at least one of sieving and classification. Claim 5 A method for producing spherical alumina powder according to claim 3, wherein the purification step is performed by at least one of washing, wet sieving, and drying. Claim 6 As spherical alumina powder, manufactured by the method according to Claim 1, having an average particle size (D) of 1-15 μm 50 ) having, and the spherical alumina powder is 0.1-2.0 m 2 Spherical alumina powder having a specific surface area of ​​ / g; a degree of sphericity of 0.90 or more; a uranium content of 5 ppb or less; an ionic impurity content of 10 ppm or less; and an electrical conductivity of 10 μS / cm or less. Claim 7 In claim 6, the spherical alumina powder has an average particle size (D) of 3-5 μm. 50 ) and maximum particle size of 20 μm or less (D 100 A first powder having ); an average particle size (D) of 8-15 μm 50 ) and maximum particle size of 45 μm or less (D 100 A second powder having ); an average particle size of 1-3 μm (D 50 ) and maximum particle size of 15 μm or less (D 100 A third powder having ); or a spherical alumina powder comprising a combination thereof. Claim 8 In claim 6, the spherical alumina powder has an average particle size (D) of 3-5 μm. 50 ) and maximum particle size of 20 μm or less (D 100 A first powder having ); an average particle size (D) of 8-15 μm 50 ) and maximum particle size of 45 μm or less (D 100 A second powder having ) and an average particle size (D) of 1-3 μm 50 ) and maximum particle size of 15 μm or less (D 100 Spherical alumina powder comprising at least two of the third powders having ). Claim 9 In claim 6, the spherical alumina powder has an average particle size (D) of 3-5 μm. 50 ) and maximum particle size of 20 μm or less (D 100 A first powder having ); an average particle size (D) of 8-15 μm 50 ) and maximum particle size of 45 μm or less (D 100 A second powder having ) and an average particle size (D) of 1-3 μm 50 ) and maximum particle size of 15 μm or less (D 100 Spherical alumina powder comprising all of the third powder having ). Claim 10 A filler comprising spherical alumina powder according to claim 6 as a filler. Claim 11 A thermally conductive resin composition comprising a filler and a resin according to claim 10. Claim 12 As an encapsulant, an encapsulant formed from a thermally conductive resin composition according to claim 11. Claim 13 A device, encapsulated in a thermally conductive resin composition according to claim 11. Claim 14 delete

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