Preparation method of high-thermal-conductivity 99 alumina ceramic substrate

Abstract

The invention provides a preparation method of a high-thermal-conductivity 99 aluminum oxide ceramic substrate, and belongs to the field of electronic ceramic materials. The method comprises the following steps: homogenizing and grinding a high-purity aluminum-containing compound and a modifier to obtain pretreated powder; mixing the pretreated powder with a carrier gas, and carrying out melt spheroidization to obtain a submicron spherical alumina precursor raw material; homogenizing and defoaming the submicron spherical aluminum oxide precursor raw material, an inorganic sintering aid, a dispersing agent, a binder, a plasticizer and a foam inhibitor in a solvent to obtain ceramic slurry; carrying out tape casting on the ceramic slurry to obtain an aluminum oxide green body; the alumina green body is subjected to rubber discharging, pre-sintering and sintering, and the 99 alumina ceramic substrate is obtained. The submicron spherical alumina powder is prepared through a melt spheroidizing process, the surface of the powder is smooth, particle size distribution is concentrated, grain boundary resistance between the powder is remarkably reduced, sintering densification is promoted, and therefore the technical problems that existing tape casting slurry is poor in stability and high in sintering temperature, and consequently microdefects are caused are solved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic ceramic materials, and in particular to a method for preparing a high thermal conductivity 99% alumina ceramic substrate. Background Art

[0002] Alumina ceramic substrates (Al2O3), as core materials in the field of electronic packaging, are widely used in high-reliability scenarios such as high-power LED heat dissipation substrates, power electronic device packaging (such as IGBT modules), and high-frequency communication components due to their high insulation, high temperature resistance, chemical stability, and mechanical strength. Among them, 99 alumina (Al2O3 content ≥ 99%) has a higher purity, a thermal conductivity of more than 26W / m·K, and lower dielectric loss (<0.0002), making it the preferred material for high-power density devices. With the surge in demand for miniaturization, high frequency, and high heat dissipation performance of devices in 5G communications, new energy vehicles, and aerospace, the market has put forward higher requirements for the thermal conductivity of alumina substrates. The development of alumina substrates with high thermal conductivity, low cost, and process stability has become an urgent need in the industry.

[0003] Currently, high thermal conductivity alumina substrates are mainly prepared by traditional alumina powder tape casting. Due to the uneven shape of the raw material particles, the grain boundaries are complicated after sintering, and the submicron powder is easy to agglomerate, so it needs to rely on ball milling for dispersion. There are disadvantages such as poor slurry stability and high sintering temperature (which often leads to microscopic defects). Summary of the Invention

[0004] The present application provides a method for preparing a high thermal conductivity 99 alumina ceramic substrate to solve the technical problems of poor stability of existing tape-casting slurry and microscopic defects caused by high sintering temperature.

[0005] The present invention provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the method comprising:

[0006] Homogenizing and grinding the high-purity aluminum-containing compound and the modifier to obtain a pretreated powder;

[0007] The pretreated powder is mixed with a carrier gas to be melted and spheroidized, and then subjected to deep purification, filtration separation and microwave drying to obtain a submicron spherical alumina precursor raw material;

[0008] Homogenize and degas the submicron spherical alumina precursor raw material, inorganic sintering aid, dispersant, binder, plasticizer and antifoaming agent in a solvent to obtain a ceramic slurry;

[0009] tape-casting the ceramic slurry to obtain an alumina green body; and

[0010] Debinding, pre-sintering and sintering the alumina green body to obtain a 99% alumina ceramic substrate;

[0011] Wherein, the inorganic sintering aid is composed of magnesium oxide, zirconium dioxide and yttrium oxide, the mass of the magnesium oxide is 0.1% to 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of the zirconium dioxide is 0.1% to 0.5% of the mass of the submicron spherical alumina precursor raw material, and the mass of the yttrium oxide is 0.01% to 0.2% of the mass of the submicron spherical alumina precursor raw material;

[0012] The sintering temperature is 1550° C. to 1650° C., and the sintering time is 1 hour to 2 hours.

[0013] Optionally, the high-purity aluminum-containing compound includes at least one of 3N alumina trihydrate, 4N alumina trihydrate, 5N alumina trihydrate, 3N alumina monohydrate, 4N alumina monohydrate, 5N alumina monohydrate, 3N alumina, 4N alumina and 5N alumina, and the average particle size of the high-purity aluminum-containing compound is 0.8 μm to 1.2 μm.

[0014] Optionally, the modifier is a silane coupling agent, and the mass of the modifier is 0.5% to 2.0% of the mass of the high-purity aluminum-containing compound.

[0015] Optionally, the homogenization grinding time is 30 min to 60 min, and the ball-to-material ratio of the homogenization grinding is (2 to 2.5):1; and / or,

[0016] The volume ratio of the carrier gas to the fuel gas in the molten spheroidization is (2.0-2.2):1, the carrier gas is air or oxygen, and the carrier gas pressure is 0.5 MPa-0.6 MPa; and / or,

[0017] The deep purification is filtering and washing with high-purity water, the number of filtering and washing is 2 to 3 times, and the liquid-to-solid ratio of the filtering and washing is (2.5 to 3.0):1; and / or,

[0018] The microwave drying is used to control the moisture content of the submicron spherical alumina precursor raw material after drying to be ≤0.1%.

[0019] Optionally, the solvent includes an azeotropic solution of ethanol mixed with any two of ethyl acetate, butanone, xylene and isopropanol;

[0020] The dispersant includes at least one of oleic acid, triolein and fish oil;

[0021] The binder is polyvinyl butyral;

[0022] The plasticizer includes at least one of polyethylene glycol and dibutyl phthalate;

[0023] The foam suppressor is a fatty acid lipid mixture.

[0024] Optionally, the mass of the dispersant is 0.5% to 1.0% of the mass of the submicron spherical alumina precursor raw material;

[0025] The mass of the binder is 6% to 10% of the mass of the submicron spherical alumina precursor raw material;

[0026] The mass of the plasticizer is 5% to 12% of the mass of the submicron spherical alumina precursor raw material;

[0027] The mass of the antifoaming agent is 0.05% to 0.5% of the mass of the submicron spherical alumina precursor raw material.

[0028] Optionally, the solid content of the ceramic slurry is 50% to 65%;

[0029] The viscosity of the ceramic slurry is 8000 mPa·s to 15000 mPa·s.

[0030] Optionally, the homogenization degassing is a multi-stage vacuum stirring degassing, and the multi-stage vacuum stirring degassing includes the following parameters: vacuum degree of 0.5Kpa~100Kpa, stirring degassing time of 5min~30min, and stirring speed of 500r / min~2000r / min.

[0031] Optionally, the debinding process is a multi-stage debinding process, the debinding temperature of the multi-stage debinding process is 300° C. to 600° C., and the debinding time of the multi-stage debinding process is 8 hours to 12 hours; and / or,

[0032] The pre-firing temperature is 1100° C. to 1200° C., and the pre-firing time is 1 hour to 2 hours.

[0033] Optionally, the 99 alumina ceramic substrate meets the following properties: thickness of 0.05 mm to 0.5 mm, sintered density ≥ 3.93 g / cm 3 , thermal conductivity ≥ 26W / m·k, flexural strength ≥ 400Mpa.

[0034] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0035] The embodiment of the present application provides a method for preparing a high-thermal-conductivity 99% alumina ceramic substrate, which comprises: homogenizing and grinding a high-purity aluminum-containing compound and a modifier to obtain a pretreated powder; mixing the pretreated powder with a carrier gas for melt spheroidization, and performing deep purification, filtration separation, and microwave drying to obtain a submicron spherical alumina precursor raw material; homogenizing and degassing the submicron spherical alumina precursor raw material, an inorganic sintering aid, a dispersant, a binder, a plasticizer, and a foam suppressant in a solvent to obtain a ceramic slurry; performing tape casting on the ceramic slurry to obtain an alumina green body; and performing binder removal, pre-sintering, and sintering on the alumina green body to obtain a 99% alumina ceramic substrate. Submicron spherical alumina powder is prepared by a melt spheroidization process for tape casting. The powder has a smooth surface and a concentrated particle size distribution, which significantly reduces the grain boundary resistance between powders and promotes sintering densification. The spherical particle characteristics have dual advantages: on the one hand, it improves the powder fluidity, reduces the viscosity of the casting slurry, and achieves high solid content molding (reducing the amount of organic binder and avoiding the risk of sintering debinding and cracking); on the other hand, through the close packing effect and the synergistic optimization of the flux, the sintering temperature can be reduced by 50℃ to 100℃ compared with the traditional process, while still achieving a density of ≥3.9g / cm 3 The high densification level of the tape casting film significantly improves the thermal conductivity, thus solving the technical problems of poor stability of the existing tape casting slurry and micro defects caused by high sintering temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] Figure 1 A schematic flow chart of a method for preparing a high thermal conductivity 99 alumina ceramic substrate provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0041] Figure 1 A schematic flow chart of a method for preparing a high thermal conductivity 99 alumina ceramic substrate provided in an embodiment of the present application.

[0042] like Figure 1 As shown, the embodiment of the present application provides a method for preparing a high thermal conductivity 99 alumina ceramic substrate, the method comprising:

[0043] S1. Homogenize and grind a high-purity aluminum-containing compound and a modifier to obtain a pretreated powder;

[0044] In some embodiments, the high-purity aluminum-containing compound includes at least one of 3N alumina trihydrate, 4N alumina trihydrate, 5N alumina trihydrate, 3N alumina monohydrate, 4N alumina monohydrate, 5N alumina monohydrate, 3N alumina, 4N alumina and 5N alumina, and the average particle size of the high-purity aluminum-containing compound is 0.8 μm to 1.2 μm.

[0045] High purity (3N and above) can reduce the negative impact of impurity phases (such as SiO2, Fe2O3) on grain boundary thermal conductivity, and the particle size range of 0.8μm to 1.2μm can balance sintering activity and dispersibility. If the average particle size is greater than 1.5μm, it will lead to insufficient sintering density. If the average particle size is less than 0.5μm, it is easy to cause agglomeration due to high surface energy, increasing the viscosity of the slurry. For example, the average particle size of the high-purity aluminum-containing compound can be 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, etc.

[0046] In some embodiments, the modifier is a silane coupling agent, and the mass of the modifier is 0.5% to 2.0% of the mass of the high-purity aluminum-containing compound.

[0047] The modifier is a silane coupling agent. The silanol generated by silane hydrolysis condenses with the hydroxyl groups on the surface of Al2O3 to form an organic coating layer, which reduces the van der Waals force between powders and reduces agglomeration.

[0048] The purpose of the modifier is to increase the dispersibility and fluidity of the raw material powder in the melt spheroidization production, reduce powder agglomeration, and make the produced spherical alumina particle size uniform and concentrated. The reason for controlling the mass of the modifier to 0.5% to 2.0% of the mass of the high-purity aluminum-containing compound is that within this ratio range, the silanol generated by the hydrolysis of the modifier fully condenses with the hydroxyl groups on the surface of the alumina, and the organic functional groups are evenly anchored on the entire surface of the alumina, thereby increasing the dispersion between the powder raw materials and reducing agglomeration. The adverse effect of too large a ratio is that the excessive modifier will undergo self-polymerization, reducing the powder modification effect and increasing the modification process cost. The adverse effect of too small a ratio is that it cannot react with all the hydroxyl groups on the surface of the alumina, and some of them are easily agglomerated without modification, resulting in poor uniformity of the spheroidized powder particle size. For example, the mass of the modifier can be 0.5%, 0.7%, 0.9%, 1.0%, 1.4%, 1.7%, 2.0%, etc. of the mass of the high-purity aluminum-containing compound.

[0049] In some embodiments, the homogenization grinding time is 30 min to 60 min, and the ball-to-material ratio of the homogenization grinding is (2 to 2.5):1.

[0050] The reason for controlling the homogenization grinding time to 30 to 60 minutes is that the powder is dispersed with the modifier, deagglomerated, and heated during the homogenization grinding process, allowing the modifier to be efficiently and evenly dispersed on the powder surface and activating the hydroxyl groups on the powder surface. The disadvantage of too long a time is that homogenization grinding for too long may lead to further refinement of the powder, resulting in a wider and less concentrated particle size distribution of the spheroidized powder. The disadvantage of too short a time is that the modifier cannot be effectively and evenly dispersed on the powder surface, and the activation temperature of the hydroxyl groups on the alumina surface is not reached, preventing reaction with the modifier. The ball-to-powder ratio is limited to (2 to 2.5):1 to ensure sufficient impact and shearing of the powder by the grinding media while avoiding excessive grinding that leads to excessively fine powder particles. For example, the time for homogenization grinding can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc., and the ball-to-material ratio of homogenization grinding can be 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, etc.

[0051] S2. Mixing the pretreated powder with a carrier gas to perform melting and spheroidization, and performing deep purification, filtration separation and microwave drying to obtain a submicron spherical alumina precursor raw material;

[0052] In some embodiments, the volume ratio of the carrier gas to the fuel gas in the molten spheroidization is (2.0-2.2):1, the carrier gas is air or oxygen, and the carrier gas pressure is 0.5 MPa-0.6 MPa.

[0053] The high-temperature melting of the carrier gas (such as nitrogen) in the melt spheroidization technology causes the alumina particles to spheroidize under the action of surface tension. The ratio of carrier gas (air / oxygen) to fuel gas controls the combustion temperature and atmosphere, (2.0-2.2):1 to ensure that the alumina raw material is fully melted; the pressure of 0.5MPa-0.6MPa ensures the carrier gas's ability to carry the powder, so that the molten particles are uniformly spheroidized in the air flow, avoiding powder deposition due to insufficient pressure or particle splashing due to excessive pressure. For example, the volume ratio of carrier gas to fuel gas for melt spheroidization can be 2.0:1, 2.05:1, 2.1:1, 2.15:1, 2.2:1, etc., and the carrier gas pressure can be 0.5Mpa, 0.52Mpa, 0.54Mpa, 0.56Mpa, 0.58Mpa, 0.6Mpa, etc.

[0054] In some embodiments, the deep purification is filtering and washing with high-purity water, the number of filtering and washing is 2 to 3 times, and the liquid-to-solid ratio of the filtering and washing is (2.5 to 3.0):1.

[0055] Washing is used to remove impurities remaining during the spheroidization process (such as metal ions and unreacted modifiers). 2 to 3 washes can balance the impurity removal efficiency and production costs. A liquid-to-solid ratio of 2.5 to 3.0:1 ensures that the powder is fully dispersed in water, improving the dissolution and filtration of impurities.

[0056] In some embodiments, the microwave drying is used to control the moisture content of the submicron spherical alumina precursor raw material after drying to be ≤0.1%.

[0057] Microwave drying can quickly and evenly remove moisture from powders, avoiding localized agglomeration caused by traditional drying. A moisture content of ≤ 0.1% prevents viscosity fluctuations during subsequent slurry preparation due to excess moisture, which can affect tape casting stability. For example, the moisture content of the submicron spherical alumina precursor raw material can be 0.1%, 0.09%, 0.08%, 0.07%, 0.06%, 0.05%, etc.

[0058] S3, homogenizing and degassing the submicron spherical alumina precursor raw material, inorganic sintering aid, dispersant, binder, plasticizer and antifoaming agent in a solvent to obtain a ceramic slurry;

[0059] In some embodiments, the inorganic sintering aid is composed of magnesium oxide, zirconium dioxide and yttrium oxide, the mass of the magnesium oxide is 0.1% to 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of the zirconium dioxide is 0.1% to 0.5% of the mass of the submicron spherical alumina precursor raw material, and the mass of the yttrium oxide is 0.01% to 0.2% of the mass of the submicron spherical alumina precursor raw material.

[0060] In some embodiments, the solvent comprises an azeotropic solution of ethanol mixed with any two of ethyl acetate, butanone, xylene, and isopropanol;

[0061] The dispersant includes at least one of oleic acid, triolein and fish oil;

[0062] The binder is polyvinyl butyral;

[0063] The plasticizer includes at least one of polyethylene glycol and dibutyl phthalate;

[0064] The foam suppressor is a fatty acid lipid mixture.

[0065] It should be noted that the fatty acid lipid mixture can be composed of higher carbon alcohol fatty acid esters, polyglycerol fatty acid esters and modified fatty acid ester complexes.

[0066] In some embodiments, the mass of the dispersant is 0.5% to 1.0% of the mass of the submicron spherical alumina precursor raw material;

[0067] The mass of the binder is 6% to 10% of the mass of the submicron spherical alumina precursor raw material;

[0068] The mass of the plasticizer is 5% to 12% of the mass of the submicron spherical alumina precursor raw material;

[0069] The mass of the antifoaming agent is 0.05% to 0.5% of the mass of the submicron spherical alumina precursor raw material.

[0070] The magnesium oxide in the inorganic sintering aid can reduce the sintering temperature, promote the uniform growth of alumina grains, and inhibit grain boundary defects; zirconium dioxide can utilize the phase transformation toughening effect to improve the flexural strength of the ceramic; yttrium oxide forms a solid solution with alumina, improves the grain boundary migration ability, and promotes densification. For example, the mass of magnesium oxide can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc. of the mass of the submicron spherical alumina precursor raw material, the mass of zirconium dioxide can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc. of the mass of the submicron spherical alumina precursor raw material, and the mass of yttrium oxide can be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, etc. of the mass of the submicron spherical alumina precursor raw material.

[0071] Ethanol forms an azeotropic solution with solvents such as ethyl acetate, which can adjust the volatilization rate to ensure uniform volatilization of the solvent during tape casting and avoid cracking or deformation of the green body.

[0072] The dispersant forms an electrostatic repulsion layer by adsorbing on the powder surface, preventing particle agglomeration and ensuring slurry uniformity. For example, the mass of the dispersant is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc., of the mass of the submicron spherical alumina precursor raw material.

[0073] The binder can provide the bonding force required for slurry molding, ensuring the strength and flexibility of the tape-cast green body. For example, the mass of the binder can be 6%, 6.5%, 7%, 7.5%, 8%, 9%, 10%, etc. of the mass of the submicron spherical alumina precursor raw material.

[0074] The plasticizer can lower the glass transition temperature of the binder, increase the ductility of the green body, and prevent cracking during the casting process. For example, the mass of the plasticizer can be 5%, 7%, 9%, 10%, 12%, etc. of the mass of the submicron spherical alumina precursor raw material.

[0075] The foam suppressant can destroy the bubble interface in the slurry and prevent the occurrence of pore defects in the tape-cast green body. For example, the mass of the foam suppressant can be 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc. of the mass of the submicron spherical alumina precursor raw material.

[0076] In some embodiments, the homogenization degassing is a multi-stage vacuum stirring degassing, and the multi-stage vacuum stirring degassing includes the following parameters: the vacuum degree of the multi-stage vacuum stirring degassing can be 0.5Kpa~100Kpa, the stirring degassing time can be 5min~30min, and the stirring speed is 500r / min~2000r / min.

[0077] The purpose of multi-stage vacuum stirring and degassing is to homogenize the ceramic slurry, remove the bubbles in the ceramic slurry, and control the viscosity of the ceramic slurry within the range suitable for tape casting. The reason for controlling the degassing time to 5min~30min and the stirring speed to 500r / min~2000r / min is that within this range, the slurry is uniform, there is no large particle agglomeration, and the viscosity is appropriate. The adverse effects of too long degassing time and too high stirring speed are: excessive degassing may cause excessive volatilization of the solvent in the slurry, excessive increase in the slurry viscosity, and no fluidity of the slurry. The adverse effects of too short degassing time and too low stirring speed are: uneven mixing of the slurry, large particle agglomeration, more bubbles in the slurry, and too many defects in the green body during tape casting. Illustratively, the vacuum degree can be 0.5 Kpa, 5 Kpa, 10 Kpa, 30 Kpa, 50 Kpa, 70 Kpa, 90 Kpa, 100 Kpa, etc., the stirring and degassing time can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, etc., and the stirring speed can be 500 r / min, 750 r / min, 1000 r / min, 1200 r / min, 1500 r / min, 1800 r / min, 2000 r / min, etc.

[0078] In some embodiments, the solid content of the ceramic slurry is 50% to 65%;

[0079] The viscosity of the ceramic slurry is 8000 mPa·s to 15000 mPa·s.

[0080] The solid content determines the density of the ceramic substrate. 50% to 65% balances the fluidity of the slurry with sintering shrinkage. The viscosity controls the coating effect of the casting blade. 8000 to 15000 mPa·s ensures a uniform thickness of the green body without sagging or cracking. For example, the solid content of the ceramic slurry can be 50%, 52%, 55%, 58%, 60%, 65%, etc., and the viscosity of the ceramic slurry can be 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, 12000 mPa·s, 14000 mPa·s, 15000 mPa·s, etc.

[0081] S4, tape-casting the ceramic slurry to obtain an alumina green body; and

[0082] Tape casting coats the slurry into a green body with a thickness of 0.05mm to 0.5mm by controlling the scraper height and conveyor belt speed. The slurry viscosity and solid content directly affect the thickness uniformity and surface smoothness of the green body.

[0083] S5, debinding, pre-sintering and sintering the alumina green body to obtain a 99% alumina ceramic substrate;

[0084] Multi-stage debinding removes organic matter (binders, plasticizers, etc.) in the green body in stages; pre-sintering can initially sinter the green body, remove residual trace organic matter, and at the same time initially bond the alumina particles, thereby improving the strength of the green body and laying a structural foundation for subsequent high-temperature sintering; sintering can achieve densification of alumina particles through diffusion and grain boundary migration at high temperature.

[0085] In some embodiments, the debinding process is a multi-stage debinding process, the debinding temperature of the multi-stage debinding process is 300° C. to 600° C., and the debinding time of the multi-stage debinding process is 8 hours to 12 hours.

[0086] By controlling the debinding temperature of multi-stage debinding to 300°C to 600°C and the debinding time to 8h to 12h, the alumina ceramic green body can be completely, slowly and orderly debinded, improving the ceramic density and enhancing the sintered density and strength of the alumina ceramic substrate. A debinding temperature greater than 600°C for multi-stage debinding has the following adverse effects: excessively rapid debinding volatilization, which can easily cause deformation and defects in the alumina green body. A debinding temperature less than 300°C for multi-stage debinding has the following adverse effects: complete volatilization of organic matter during the debinding stage, followed by rapid volatilization during subsequent temperature increase, which can cause deformation of the sintered ceramic and the appearance of defects such as pores. For example, the sintering temperature is 1550°C, 1570°C, 1590°C, 1600°C, 1620°C, 1650°C, etc., and the sintering time can be 1h, 1.2h, 1.5h, 1.8h, 2h, etc.

[0087] In some embodiments, the pre-firing temperature is 1100° C. to 1200° C., and the pre-firing time is 1 hour to 2 hours.

[0088] In some embodiments, the sintering temperature is 1550° C. to 1650° C., and the sintering time is 1 hour to 2 hours.

[0089] Controlling the pre-sintering temperature to 1100-1200°C prevents excessively high pre-sintering temperatures, which can lead to premature grain growth and compromise final density. Controlling the pre-sintering time to 1-2 hours ensures initial bonding between particles, forming a green body with a certain strength for subsequent processing. Sintering at high temperatures densifies alumina particles through mechanisms such as diffusion and creep, forming a porous ceramic matrix. Excessively high pre-sintering and sintering temperatures can lead to abnormal grain growth and poor performance of the alumina ceramic substrate. Excessively low pre-sintering and sintering temperatures can result in low sintered density and insufficient substrate strength. Exemplarily, the pre-firing temperature can be 1100°C, 1120°C, 1140°C, 1160°C, 1180°C, 1200°C, etc., the pre-firing time can be 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, etc., the sintering temperature can be 1550°C, 1570°C, 1590°C, 1610°C, 1630°C, 1650°C, etc., and the sintering time can be 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, etc.

[0090] In some embodiments, the 99 alumina ceramic substrate meets the following properties: thickness of 0.05 mm to 0.5 mm, sintered density ≥ 3.93 g / cm 3 , thermal conductivity ≥ 26W / m·k, flexural strength ≥ 400Mpa.

[0091] The embodiment of the present application provides a method for preparing a high thermal conductivity 99 alumina ceramic substrate, in which submicron spherical alumina powder is prepared by a melt spheroidization process for tape casting. The powder surface is smooth and the particle size distribution is concentrated, which significantly reduces the grain boundary resistance between powders and promotes sintering densification. The spherical particle characteristics have dual advantages: on the one hand, it improves the fluidity of the powder, reduces the viscosity of the tape casting slurry, and realizes high solid content molding (reduces the amount of organic binder and avoids the risk of sintering debinding and cracking); on the other hand, through the coordinated optimization of the close stacking effect and the flux, the sintering temperature is reduced by 50℃~100℃ compared with the traditional process, and the density ≥3.9g / cm 3 The high densification level significantly improves thermal conductivity. In addition, the simplified process route (no complex grinding required) reduces energy consumption and processing complexity, conforming to the concept of green manufacturing and providing a new path for domestic high-end ceramic substrates to replace imported ones.

[0092] Therefore, this application obtains a precursor powder raw material with uniform particle size, concentrated distribution and good dispersibility through production control of submicron spherical alumina as a precursor raw material, and efficiently mixes and degasses the precursor powder raw material with inorganic sintering aids, solvents, dispersants, binders, plasticizers and other casting aids to control the uniformity and viscosity of the slurry, and casts alumina green bodies of different thicknesses. After debinding, pre-sintering and sintering, a 99 alumina ceramic substrate with controllable thickness of 0.05mm to 0.3mm, stable quality and high thermal conductivity is obtained. The sintered density of its 99 alumina ceramic substrate is ≥3.93g / cm 3 , thermal conductivity ≥ 26W / m·k, flexural strength ≥ 400Mpa, dense and uniform microstructure, meeting the technical requirements of high-end electronic heat dissipation field.

[0093] In summary, this application achieves a triple breakthrough in performance, process, and cost for 99% alumina ceramic substrates through the technical route of "spherical powder design - precise slurry control - low-temperature dense sintering". Its core advantage lies in the in-depth combination of material microstructure control and process parameter optimization, which not only meets the stringent requirements of high-end electronic heat dissipation, but also has the economic feasibility of large-scale production. The specific advantages are summarized as follows:

[0094] 1. Material Performance Advantages: Breakthroughs in High-Performance Indicators and Microstructure Optimization

[0095] (1) High densification and improved thermal conductivity: Using submicron spherical alumina precursor (uniform particle size and good dispersion) and MgO / ZrO2 / Y2O3 composite sintering aid, the sintering density is ≥3.93g / cm 3 , thermal conductivity ≥ 26W / m·K, an improvement of 10% to 15% over traditional processes. The dense packing effect of spherical particles reduces grain boundary thermal resistance, and the trace solid solution formed by the sintering aid optimizes the phonon transmission path, achieving a synergistic improvement in thermal conductivity and densification. At the same time, the microstructure is dense and uniform (grain size can be controlled at 1 to 3μm), and the flexural strength is ≥ 400MPa, meeting the dual requirements of substrate strength and heat dissipation for high-end electronic packaging.

[0096] (2) Thinness and dimensional stability: Tape casting can produce ultra-thin green sheets of 0.05-0.5 mm. Through multi-stage debinding (300-600°C, 8-12h) and precise sintering control (1550-1650°C), deformation and cracking of thin substrates can be avoided. The thickness tolerance is ≤±5%, which is suitable for ultra-thin heat dissipation scenarios such as 5G chips and power devices.

[0097] 2. Process Technology Advantages: Innovative processes and parameters synergistically reduce costs and increase efficiency

[0098] (1) A revolutionary breakthrough in the melt spheroidization process: Using a melt spheroidization technology with a carrier gas to fuel gas volume ratio of 2.0 to 2.2:1 and a pressure of 0.5 to 0.6 MPa, the alumina particles are naturally spheroidized in a high-temperature airflow, resulting in a smooth surface and a concentrated particle size distribution (D50 = 0.8 to 1.2 μm). Compared with traditional grinding processes, the powder dispersibility is improved by 30%, and no subsequent complex crushing process is required, reducing energy consumption by 20%. Silane coupling agent modification (dosage 0.5% to 2.0%) and 30 to 60 minutes of homogenization grinding work together to avoid powder agglomeration, laying the foundation for particle size uniformity after spheroidization. The first-time pass rate of spheroidized powder is ≥95%.

[0099] (2) Precise control of slurry regulation and tape casting: Multi-stage vacuum stirring and degassing (vacuum degree 0.5~100KPa, rotation speed 500~2000r / min) can achieve precise control of slurry solid content of 50%~65% and viscosity of 8000~15000mPa·s. The high solid content reduces the amount of organic additives (binder is only 6%~10%), and the risk of cracking in the debinding stage is reduced by 40%. At the same time, the surface flatness of the green body Ra ≤ 0.5μm.

[0100] (3) Low-temperature sintering and energy consumption optimization: The sintering temperature is reduced by 50-100°C (1550-1650°C) compared with the traditional process, while still achieving a high density level. Thanks to the high sintering activity of the spherical powder and the grain boundary control effect of the sintering aid, the energy consumption of a single furnace is reduced by 15%, and the production cycle is shortened by 10%-15%.

[0101] 3. Cost and Environmental Advantages: Process Simplification and Green Manufacturing

[0102] (1) Simplified process flow: The complex steps of multi-stage grinding and wet purification in traditional processes are omitted. High-purity precursors are directly prepared through melt spheroidization and microwave drying (moisture content ≤ 0.1%), reducing equipment investment by 30% and increasing production efficiency by 25%. The amount of inorganic sintering aids used is low (MgO / ZrO2 0.1% to 0.5% each), avoiding the use of toxic and harmful additives, and complying with RoHS environmental standards.

[0103] (2) Domestic substitution and industrialization potential: Breaking through the technical barriers of imported high-end ceramic substrates, reducing material costs by 40%, and achieving performance indicators (thermal conductivity, strength) at the level of similar international products, providing key material support for the localization of semiconductors, new energy vehicles and other fields.

[0104] 4. Application scenario adaptability: high-end cooling solutions in multiple fields

[0105] (1) Electronic packaging field: 0.05~0.3mm ultra-thin substrates are suitable for the high-density heat dissipation requirements of flip chips and power modules, and the thermal conductivity of 26W / m·K can meet the requirements of 100W / cm 2 Heat flux scenario above.

[0106] (2) New Energy and Aerospace: High-reliability substrates with a bending strength of ≥400MPa, which can withstand extreme temperature cycles (-50℃~200℃), are suitable for heat dissipation substrates of vehicle-mounted inverters and avionics equipment.

[0107] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0108] Example 1

[0109] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0110] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 1.0 μm and 1.0% silane coupling agent KH-550, control the homogenization grinding ball-to-material ratio to 2.5:1, and homogenize for 60 min to obtain a pretreated powder with good fluidity and good dispersibility.

[0111] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.6 MPa, and the ratio of oxygen to natural gas is 2.1:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 2.5:1, and washed three times; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0112] S3. Add the submicron spherical alumina precursor raw material and inorganic sintering aid, oleic acid, PVB, dibutyl phthalate, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) into ethanol and ethyl acetate azeotropic solvent in turn, mix, vacuum degassing for 30 minutes, stirring at a maximum speed of 1600r / min, and a vacuum degree of 0.5Kpa~100Kpa (multi-stage degassing, the vacuum degrees involve 0.5, 1.0, 2.0, 10, 50, 100, etc.), to obtain ceramic slurry.

[0113] The mass of magnesium oxide in the inorganic assisted sintering is 0.15% of the mass of the submicron spherical alumina precursor raw material, the mass of yttrium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, and the mass of zirconium dioxide is 0.15% of the mass of the submicron spherical alumina precursor raw material.

[0114] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 10% of the mass of the submicron spherical alumina precursor raw material, the mass of dibutyl phthalate is 2% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 6% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.05% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 60%.

[0115] S4, controlling the viscosity of the ceramic slurry at 14000 mPa·s, and tape-casting to obtain an alumina green body;

[0116] S5. Debinding, pre-firing, and sintering the alumina green body to obtain a 99% alumina ceramic substrate.

[0117] The debinding temperature is 300℃ and 500℃, and the debinding time is 4h each; the pre-firing temperature is 1200℃, and the pre-firing time is 2h; the sintering temperature is 1600℃, and the sintering time is 2h.

[0118] Example 2

[0119] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0120] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 1.2 μm and 1.5% silane coupling agent KH-570, control the homogenization grinding ball-to-material ratio to 2.0:1, and homogenize for 60 min to obtain a pretreated powder with good fluidity and good dispersibility.

[0121] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.6 MPa, and the ratio of oxygen to natural gas is 2.1:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 3.0:1, and washed twice; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0122] S3. Add the submicron spherical alumina precursor raw materials and inorganic sintering aid, oleic acid, PVB, dibutyl phthalate, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) into ethanol and butanone azeotropic solvent in turn, mix, vacuum degassing for 20 minutes, stirring at a maximum speed of 2000r / min, and a vacuum degree of 0.5Kpa~100Kpa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.), to obtain ceramic slurry.

[0123] The mass of magnesium oxide in the inorganic assisted sintering is 0.20% of the mass of the submicron spherical alumina precursor raw material, the mass of yttrium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, and the mass of zirconium dioxide is 0.10% of the mass of the submicron spherical alumina precursor raw material.

[0124] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 8% of the mass of the submicron spherical alumina precursor raw material, the mass of dibutyl phthalate is 2% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 6% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.1% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 60%.

[0125] S4, controlling the viscosity of the ceramic slurry at 12000 mPa·s, and tape-casting to obtain an alumina green body;

[0126] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0127] The debinding temperatures are 300°C and 550°C, and the debinding time is 5 hours each; the pre-firing temperature is 1100°C, and the pre-firing time is 2 hours; the sintering temperature is 1620°C, and the sintering time is 2 hours.

[0128] Example 3

[0129] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0130] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 0.8 μm and 2.0% silane coupling agent KH-580, control the homogenization grinding ball-to-material ratio to 2.0:1, and homogenize for 45 minutes to obtain a pretreated powder with good fluidity and good dispersibility.

[0131] S2. The pretreated powder raw material is transported into the spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.6 MPa, and the ratio of oxygen to natural gas is 2.2:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 2.5:1, and washed three times; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0132] S3. Add the submicron spherical alumina precursor raw material and inorganic sintering aid, oleic acid, PVB, dibutyl phthalate, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) in turn to ethanol and isopropanol azeotropic solvent and mix them. Vacuum degassing for 20 minutes, stirring at a maximum speed of 2000r / min, and a vacuum degree of 0.5Kpa~100Kpa (multi-stage degassing, the vacuum degrees involve 0.5, 1.0, 2.0, 10, 50, 100, etc.) to obtain ceramic slurry.

[0133] The mass of the inorganic sintering-aided magnesium oxide is 0.15% of the mass of the submicron spherical alumina precursor raw material, the mass of the yttrium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.15% of the mass of the submicron spherical alumina precursor raw material.

[0134] The mass of oleic acid is 0.8% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 10% of the mass of the submicron spherical alumina precursor raw material, the mass of dibutyl phthalate is 2.5% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 7.5% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.1% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 65%.

[0135] S4, controlling the viscosity of the ceramic slurry at 15000 mPa·s, and tape-casting to obtain an alumina green body;

[0136] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0137] The debinding temperatures are 300°C and 550°C, and the debinding time is 6 hours respectively; the pre-firing temperature is 1200°C, and the pre-firing time is 2 hours; the sintering temperature is 1580°C, and the sintering time is 2 hours.

[0138] Example 4

[0139] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0140] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 1.0 μm and 0.5% silane coupling agent KH-550, control the homogenization grinding ball-to-material ratio to 2.0:1, and homogenize for 30 minutes to obtain a pretreated powder with good fluidity and good dispersibility.

[0141] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.5 MPa, and the ratio of oxygen to natural gas is 2.2:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 3.0:1, and washed twice; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0142] S3. Add the submicron spherical alumina precursor raw material, inorganic sintering aid, oleic acid, PVB, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) in turn into ethanol and butyl acetate azeotropic solvent and mix them. Vacuum degassing for 10 minutes, stirring at a maximum speed of 2000r / min, and a vacuum degree of 0.5KPa~100KPa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.) to obtain ceramic slurry.

[0143] The mass of the inorganic sintering-aided magnesium oxide is 0.15% of the mass of the submicron spherical alumina precursor raw material, the mass of the yttrium oxide is 0.05% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.10% of the mass of the submicron spherical alumina precursor raw material.

[0144] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 6% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 6% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.1% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 58%.

[0145] S4, controlling the viscosity of the ceramic slurry at 10000 mPa·s, and tape-casting to obtain an alumina green body;

[0146] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0147] The debinding temperatures are 300°C and 550°C, and the debinding time is 4 hours each; the pre-firing temperature is 1200°C, and the pre-firing time is 2 hours; the sintering temperature is 1650°C, and the sintering time is 2 hours.

[0148] Example 5

[0149] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0150] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 0.8 μm and 1.0% silane coupling agent KH-570, control the homogenization grinding ball-to-material ratio to 2.0:1, and homogenize for 60 min to obtain a pretreated powder with good fluidity and good dispersibility.

[0151] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.5 MPa, and the ratio of oxygen to natural gas is 2.2:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 3.0:1, and washed twice; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0152] S3. Add the submicron spherical alumina precursor raw material, inorganic sintering aid, oleic acid, PVB, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) into ethanol and butanone azeotropic solvent in sequence, mix, vacuum degassing for 20 minutes, stirring at a maximum speed of 2000r / min, and a vacuum degree of 0.5KPa~100KPa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.), to obtain ceramic slurry.

[0153] The mass of the inorganic sintering-aided magnesium oxide is 0.15% of the mass of the submicron spherical alumina precursor raw material, the mass of the yttrium oxide is 0.05% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.10% of the mass of the submicron spherical alumina precursor raw material.

[0154] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 6% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 7.2% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.2% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 65%.

[0155] S4, controlling the viscosity of the ceramic slurry at 15000 mPa·s, and tape-casting to obtain an alumina green body;

[0156] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0157] The debinding temperatures are 300°C and 550°C, and the debinding time is 6 hours respectively; the pre-firing temperature is 1200°C, and the pre-firing time is 2 hours; the sintering temperature is 1600°C, and the sintering time is 2 hours.

[0158] Example 6

[0159] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0160] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 1.2 μm and 2.0% silane coupling agent KH-580, control the ball-to-material ratio to 2.5:1, and homogenize for 60 min to obtain a pretreated powder with good fluidity and dispersion.

[0161] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.5 MPa, and the ratio of oxygen to natural gas is 2.2:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 2.0:1, and washed three times; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0162] S3. Add the submicron spherical alumina precursor raw material, inorganic sintering aid, oleic acid, PVB, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) into ethanol and ethyl acetate azeotropic solvent in turn, mix, vacuum degassing for 30 minutes, stirring at a maximum speed of 1500r / min, and a vacuum degree of 0.5KPa~100KPa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.), to obtain ceramic slurry.

[0163] The mass of the inorganic sintering-aided magnesium oxide is 0.15% of the mass of the submicron spherical alumina precursor raw material, the mass of the yttrium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.15% of the mass of the submicron spherical alumina precursor raw material.

[0164] The mass of oleic acid is 1.0% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 6% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 4.8% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.05% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 55%.

[0165] S4, controlling the viscosity of the ceramic slurry at 10000 mPa·s, and tape-casting to obtain an alumina green body;

[0166] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0167] The debinding temperatures are 300°C and 550°C, and the debinding time is 4 hours each; the pre-firing temperature is 1150°C, and the pre-firing time is 2 hours; the sintering temperature is 1600°C, and the sintering time is 2 hours.

[0168] Comparative Example 1

[0169] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0170] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 1.0 μm and 0.3% silane coupling agent KH-550, control the ball-to-material ratio to 2.5:1, and homogenize for 20 minutes to obtain a pretreated powder with relatively good fluidity and good dispersibility.

[0171] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.6 MPa, and the ratio of oxygen to natural gas is 2.1:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 2.0:1, and washed three times; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0172] S3. Add the submicron spherical alumina precursor raw material, inorganic sintering aid, oleic acid, PVB, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) in turn into ethanol and isopropanol azeotropic solvent and mix them. Vacuum degassing for 20 minutes, stirring at a maximum speed of 1600r / min, and a vacuum degree of 0.5KPa~100KPa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.) to obtain ceramic slurry.

[0173] The mass of the inorganic sintering-aided magnesium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.10% of the mass of the submicron spherical alumina precursor raw material.

[0174] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 8% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 6.4% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.1% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 58%.

[0175] S4, controlling the viscosity of the ceramic slurry at 12000 mPa·s, and tape-casting to obtain an alumina green body;

[0176] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0177] The debinding temperatures are 300°C and 550°C, and the debinding time is 4 hours each; the pre-firing temperature is 1150°C, and the pre-firing time is 2 hours; the sintering temperature is 1600°C, and the sintering time is 2 hours.

[0178] Comparative Example 2

[0179] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0180] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 1.0 μm and 1.0% silane coupling agent KH-570, control the ball-to-material ratio to 2.5:1, and homogenize for 60 min to obtain a pretreated powder with relatively good fluidity and good dispersibility.

[0181] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.6 MPa, and the ratio of oxygen to natural gas is 2.1:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 2.0:1, and washed twice; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0182] S3. Add the submicron spherical alumina precursor raw material, inorganic sintering aid, oleic acid, PVB, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) in turn into ethanol and isopropanol azeotropic solvent and mix them. Vacuum degassing for 4 minutes, stirring at a maximum speed of 1600r / min, and a vacuum degree of 0.5KPa~100KPa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.) to obtain ceramic slurry.

[0183] The mass of the inorganic sintering-aided magnesium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.10% of the mass of the submicron spherical alumina precursor raw material.

[0184] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 10% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 8% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.1% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 60%.

[0185] S4, controlling the viscosity of the ceramic slurry at 13000 mPa·s, and tape-casting to obtain an alumina green body;

[0186] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0187] The debinding temperatures are 300°C and 550°C, and the debinding time is 4 hours each; the pre-firing temperature is 1150°C, and the pre-firing time is 2 hours; the sintering temperature is 1600°C, and the sintering time is 2 hours.

[0188] Comparative Example 3

[0189] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0190] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 1.0 μm and 1.0% silane coupling agent KH-580, control the ball-to-material ratio to 2.5:1, and homogenize for 30 minutes to obtain a pretreated powder with relatively good fluidity and good dispersibility.

[0191] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.6 MPa, and the ratio of oxygen to natural gas is 2.1:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 2.0:1, and washed twice; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0192] S3. Add the submicron spherical alumina precursor raw material, inorganic sintering aid, oleic acid, PVB, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) in turn to ethanol and isopropanol azeotropic solvent and mix them. Vacuum degassing for 15 minutes, stirring at a maximum speed of 1600r / min, and a vacuum degree of 0.5KPa~100KPa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.) to obtain ceramic slurry.

[0193] The mass of the inorganic sintering-aided magnesium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, the mass of the yttrium oxide is 0.10% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.10% of the mass of the submicron spherical alumina precursor raw material.

[0194] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 10% of the mass of the submicron spherical alumina precursor raw material, the mass of polyethylene glycol is 8% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.1% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 60%.

[0195] S4, controlling the viscosity of the ceramic slurry at 13000 mPa·s, and tape-casting to obtain an alumina green body;

[0196] S5. Debinding, pre-firing, and sintering the green body to obtain a 99% alumina ceramic substrate.

[0197] The debinding temperature is 300℃ and 600℃, and the debinding time is 3h each; the pre-firing temperature is 1000℃, and the pre-firing time is 2h; the sintering temperature is 1500℃, and the sintering time is 2h.

[0198] Comparative Example 4

[0199] This embodiment provides a method for preparing a high thermal conductivity 99% alumina ceramic substrate, the steps of which are as follows:

[0200] S1. Homogenize and grind a high-purity aluminum-containing compound with an average particle size of 0.8 μm and 0.1% silane coupling agent KH-570, control the ball-to-material ratio to 2.5:1, and homogenize for 60 min to obtain a pretreated powder with relatively good fluidity and good dispersibility.

[0201] S2. The pretreated powder raw material is transported into a spheroidizing furnace for melting and spheroidization using pure oxygen as a carrier gas, and the oxygen pressure is controlled at 0.6 MPa, and the ratio of oxygen to natural gas is 2.1:1; the obtained spheroidized powder is stirred and washed with high-purity water with a washing liquid-to-solid ratio of 2.0:1, and washed twice; after washing, it is filtered and separated, and microwave-dried to obtain a submicron spherical alumina precursor raw material with a moisture content of less than 0.1%.

[0202] S3. Add the submicron spherical alumina precursor raw material, inorganic sintering aid, oleic acid, PVB, polyethylene glycol and antifoaming agent (fatty acid lipid mixture) into ethanol and isopropanol azeotropic solvent in turn, mix, vacuum degassing for 20 minutes, stirring at a maximum speed of 1800r / min, and a vacuum degree of 0.5KPa~100KPa (multi-stage degassing, vacuum degrees involving 0.5, 1.0, 2.0, 10, 50, 100, etc.), to obtain ceramic slurry.

[0203] The mass of the inorganic sintering-aided magnesium oxide is 0.15% of the mass of the submicron spherical alumina precursor raw material, the mass of the yttrium oxide is 0.05% of the mass of the submicron spherical alumina precursor raw material, and the mass of the zirconium dioxide is 0.10% of the mass of the submicron spherical alumina precursor raw material.

[0204] The mass of oleic acid is 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of PVB is 10% of the mass of the submicron spherical alumina precursor raw material, the added amount of dibutyl phthalate is 2.25%, the mass of polyethylene glycol is 7.5% of the mass of the submicron spherical alumina precursor raw material, the mass of the antifoaming agent is 0.1% of the mass of the submicron spherical alumina precursor raw material, and the solid content of the ceramic slurry is controlled at 60%.

[0205] S4, controlling the viscosity of the ceramic slurry at 13000 mPa·s, and tape-casting to obtain an alumina green body;

[0206] S5. Debinding, pre-firing, and sintering the alumina green body to obtain a 99% alumina ceramic substrate.

[0207] The debinding temperatures are 300°C and 550°C, and the debinding time is 4 hours each; the pre-firing temperature is 1200°C, and the pre-firing time is 2 hours; the sintering temperature is 1550°C, and the sintering time is 2 hours.

[0208] The thickness, sintered density, thermal conductivity and strength of the 99 alumina ceramic substrates of Examples 1 to 6 and Comparative Examples 1 to 4 were tested. The test results are shown in Table 1.

[0209] Table 1 Performance results of 99% alumina ceramic substrates of Examples 1 to 6 and Comparative Examples 1 to 4

[0210] Group Film thickness (mm) Sintered density% Thermal conductivity W / m·k Bending strength MPa Substrate appearance Example 1 0.241 3.932 28 420 No defects Example 2 0.219 3.933 27 430 No defects Example 3 0.295 3.937 28 421 No defects Example 4 0.189 3.930 27 400 No defects Example 5 0.336 3.934 29 450 No defects Example 6 0.204 3.939 28 440 No defects Comparative Example 1 0.215 3.887 24 350 Slight edge warping Comparative Example 2 0.238 3.863 25 300 Light spot, micropore Comparative Example 3 0.285 3.891 26 380 No defects Comparative Example 4 0.255 3.928 27 390 There are bulges

[0211] As can be seen from Table 1, according to the comparison between Examples 1-6 and Comparative Examples 1-4, the high thermal conductivity 99 alumina ceramic substrate prepared by tape casting provided in the embodiments of the present invention has advantages in sintering density, thermal conductivity and substrate strength, and the thickness of the alumina ceramic substrate is controllable from 0.05 to 0.5 mm. The production batches have high stability, high yield, low cost, and significantly improved efficiency, which meets the technical requirements of alumina ceramic substrates in the field of high-end electronic heat dissipation.

[0212] The experimental parameters in the comparative example are not within the preferred parameter range of the present invention, resulting in poor dispersion of the precursor raw materials, poor morphology of the precursor spherical alumina raw materials, uneven ceramic slurry and unbalanced sintering system, etc. The final cumulative feedback to the prepared alumina ceramic substrate is manifested as performance degradation, surface defects and sintering deformation.

[0213] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0214] In the embodiment of the present application, the 99 alumina ceramic substrate produced has good thermal conductivity and mechanical properties, the production process stability is improved, the yield rate is increased, the thickness can reach 0.05mm~0.5mm, and the sintered density is ≥3.93g / cm 3 , thermal conductivity ≥ 26W / m·k, flexural strength ≥ 400Mpa.

[0215] In the embodiments of the present application, the 99 alumina ceramic substrate produced has good density, high thermal conductivity and bending strength, and a uniform microstructure, which can meet the technical requirements of high thermal conductivity 99 alumina ceramic substrates in the field of high-end electronic heat dissipation.

[0216] In the embodiment of the present application, the process route is simplified (no complex grinding is required), energy consumption and processing complexity are reduced, which is in line with the concept of green manufacturing and provides a new path for domestic high-end ceramic substrates to replace imports.

[0217] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing a high thermal conductivity 99% alumina ceramic substrate, the method comprising: Homogenizing and grinding the high-purity aluminum-containing compound and the modifier to obtain a pretreated powder; The pretreated powder is mixed with a carrier gas to be melted and spheroidized, and then subjected to deep purification, filtration separation and microwave drying to obtain a submicron spherical alumina precursor raw material; Homogenize and degas the submicron spherical alumina precursor raw material, inorganic sintering aid, dispersant, binder, plasticizer and antifoaming agent in a solvent to obtain a ceramic slurry; tape-casting the ceramic slurry to obtain an alumina green body; as well as Debinding, pre-sintering and sintering the alumina green body to obtain a 99% alumina ceramic substrate; Wherein, the inorganic sintering aid is composed of magnesium oxide, zirconium dioxide and yttrium oxide, the mass of the magnesium oxide is 0.1% to 0.5% of the mass of the submicron spherical alumina precursor raw material, the mass of the zirconium dioxide is 0.1% to 0.5% of the mass of the submicron spherical alumina precursor raw material, and the mass of the yttrium oxide is 0.01% to 0.2% of the mass of the submicron spherical alumina precursor raw material; The sintering temperature is 1550° C. to 1650° C., and the sintering time is 1 hour to 2 hours.

2. The method according to claim 1, characterized in that The high-purity aluminum-containing compound includes at least one of 3N alumina trihydrate, 4N alumina trihydrate, 5N alumina trihydrate, 3N alumina monohydrate, 4N alumina monohydrate, 5N alumina monohydrate, 3N alumina, 4N alumina and 5N alumina, and the average particle size of the high-purity aluminum-containing compound is 0.8 μm to 1.2 μm.

3. The method according to claim 1, characterized in that The modifier is a silane coupling agent, and the mass of the modifier is 0.5% to 2.0% of the mass of the high-purity aluminum-containing compound.

4. The method according to claim 1, wherein The homogenization grinding time is 30 minutes to 60 minutes, and the ball-to-material ratio of the homogenization grinding is (2 to 2.5):1; and / or, The volume ratio of the carrier gas to the fuel gas in the molten spheroidization is (2.0-2.2):1, the carrier gas is air or oxygen, and the carrier gas pressure is 0.5 MPa-0.6 MPa; and / or, The deep purification is filtering and washing with high-purity water, the number of filtering and washing is 2 to 3 times, and the liquid-to-solid ratio of the filtering and washing is (2.5 to 3.0):1; and / or, The microwave drying is used to control the moisture content of the submicron spherical alumina precursor raw material after drying to be ≤0.1%.

5. The method according to claim 1, wherein The solvent includes an azeotropic solution of ethanol mixed with any two of ethyl acetate, butanone, xylene and isopropanol; The dispersant includes at least one of oleic acid, triolein and fish oil; The binder is polyvinyl butyral; The plasticizer includes at least one of polyethylene glycol and dibutyl phthalate; The foam suppressor is a fatty acid lipid mixture.

6. The method according to claim 5, characterized in that The mass of the dispersant is 0.5% to 1.0% of the mass of the submicron spherical alumina precursor raw material; The mass of the binder is 6% to 10% of the mass of the submicron spherical alumina precursor raw material; The mass of the plasticizer is 5% to 12% of the mass of the submicron spherical alumina precursor raw material; The mass of the antifoaming agent is 0.05% to 0.5% of the mass of the submicron spherical alumina precursor raw material.

7. The method according to claim 1, characterized in that The solid content of the ceramic slurry is 50% to 65%; The viscosity of the ceramic slurry is 8000 mPa·s to 15000 mPa·s.

8. The method according to claim 1, characterized in that The homogenization degassing is a multi-stage vacuum stirring degassing, and the multi-stage vacuum stirring degassing includes the following parameters: vacuum degree is 0.5Kpa~100Kpa, stirring degassing time is 5min~30min, and stirring speed is 500r / min~2000r / min.

9. The method according to claim 1, characterized in that The debinding is a multi-stage debinding process, wherein the debinding temperature of the multi-stage debinding is 300° C. to 600° C. and the debinding time of the multi-stage debinding is 8 hours to 12 hours; and / or, The pre-firing temperature is 1100° C. to 1200° C., and the pre-firing time is 1 hour to 2 hours.

10. The method according to claim 1, characterized in that The 99 alumina ceramic substrate meets the following properties: thickness of 0.05mm to 0.5mm, sintered density ≥ 3.93g / cm 3 , thermal conductivity ≥ 26W / m·k, flexural strength ≥ 400Mpa.

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