Al2o3-aln in-situ composite ceramic and method for additive manufacturing and application thereof

Abstract

The application provides an Al2O3-AlN in-situ composite ceramic, a method for preparing the same by additive manufacturing and application, and the method comprises the following steps: mixing alumina powder, a stabilizer and a solvent, ball milling to obtain a first mixture; the first mixture is heated and stirred, and then mixed with a binder and stirred under pressure to obtain a second mixture; the second mixture is sequentially cooled and crushed, and the obtained granular material is subjected to additive manufacturing to obtain a shaped workpiece; the shaped workpiece is subjected to degreasing, and the obtained workpiece after degreasing is subjected to sintering treatment under a condition containing nitrogen elements to obtain the Al2O3-AlN in-situ composite ceramic. The application combines the low cost of Al2O3 ceramic and the high thermal conductivity of AlN ceramic, utilizes the advantage of additive manufacturing in integrated construction of complex structures, has low cost and simple operation, is beneficial to the improvement of the surface heat dissipation capacity of a chip packaging substrate, and has the advantage of solving the failure problem caused by the difference in the thermal expansion coefficients of the ceramic surface and the chip.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic materials, in particular to an Al2O3-AlN in-situ composite ceramic, a method for additive manufacturing thereof and application. BACKGROUND

[0002] At present, alumina (Al2O3) ceramic is widely used in the chip packaging substrate of thick film integrated circuit in the electronic manufacturing industry due to its low cost, simple process and good comprehensive mechanical properties. However, the thermal conductivity of Al2O3 ceramic is low, which makes it difficult to use in high-power devices. AlN ceramic substrate has high thermal conductivity and is greatly favored in high-power devices that require high thermal conductivity. With the rapid development of industrial technology, the application demand of high-power devices is steadily rising, and the application prospect of AlN ceramic substrate is very broad.

[0003] However, Al2O3 substrate has the characteristics of low thermal conductivity (25 W / mK), which is easy to cause mismatch with the thermal expansion coefficient of the chip, thereby affecting its application in super-power. AlN ceramic substrate has high thermal conductivity (210 W / mK) and gradually replaces Al2O3 substrate in high-power devices that require high thermal conductivity. However, compared with Al2O3 substrate, AlN ceramic substrate also has other problems, such as high cost of material and processing, difficult processing, and easy to be damaged due to poor toughness during use, etc.

[0004] Alumina (Al2O3) and AlN ceramic substrate often use traditional casting method, dry pressing method and subtractive machining process. The processing of ceramic substrate formed by casting method has great limitations, mainly because it is difficult to realize the manufacturing of complex structure by casting method; while the dry pressing method uses a mold to form the complex structure of the ceramic substrate in one step, but the cost of opening the mold is high, and the design of the mold with complex structure is difficult; subtractive machining is a complementary technology to casting and dry pressing, which can greatly solve the problem of structure forming, but it is easy to appear knife collapse and fracture of the processed material when manufacturing materials with high hardness such as AlN ceramic, and the processing time and material cost are also high.

[0005] Therefore, it is necessary to develop a new method for preparing Al2O3-AlN in-situ composite ceramic. SUMMARY

[0006] In view of the problems in the prior art, the application provides an Al2O3-AlN in-situ composite ceramic and a method for preparing the same by additive manufacturing and application, which reduces the cost, is simple to operate, and can solve the failure problem caused by the inconsistent thermal expansion coefficient of the Al2O3 ceramic surface and the chip, and is beneficial to improving the interface bonding strength of Al2O3 and AlN and reducing the probability of damage of the substrate during use.

[0007] To achieve the above object, the application adopts the following technical solutions:

[0008] In a first aspect, the application provides a method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing, which comprises the following steps:

[0009] (1) mixing alumina powder, a surface modifier, a stabilizer and a solvent, sequentially performing ball milling and drying to obtain a first mixture; the first mixture is heated and stirred, and then a binder is mixed and pressurized to obtain a second mixture;

[0010] (2) the second mixture is sequentially cooled and crushed to obtain a granular material; the granular material is prepared by additive manufacturing to obtain a formed workpiece;

[0011] (3) the formed workpiece is degreased to obtain a degreased workpiece, which is sintered under a condition containing nitrogen elements to obtain an Al2O3-AlN in-situ composite ceramic.

[0012] The method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing provided by the application first prepares an Al2O3 formed workpiece by additive manufacturing, which avoids the problems of material waste and high cost caused by subtractive manufacturing; and then realizes the compounding of Al2O3-AlN by in-situ compounding of AlN, so that the material has the advantages of low cost of Al2O3 ceramic and high thermal conductivity of AlN ceramic, and the in-situ compounding of Al2O3 and AlN has high bonding strength and excellent performance.

[0013] Preferably, in step (1), the mass ratio of the alumina powder, the surface modifier and the stabilizer is 15-35:1:1-3, for example, it can be 15:1:2, 16:1:1, 17:1:3, 18:1:1.5, 19:1:2.2, 20:1:2.5, 21:1:1.8, 22:1:2, 23:1:2, 24:1:2 or 25:1:2, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0014] The alumina powder without adding stabilizer in the present application will cause the content of AlN phase to decrease obviously after sintering and nitriding, the proportion of Al, O and N phases will increase, thereby causing the decline of surface heat dissipation capacity; in addition, when the mass ratio of the added stabilizer is too high, the new phase of the nitrided stabilizer will be generated, which will affect the generation of AlN.

[0015] Preferably, the stabilizer comprises zirconium oxide.

[0016] Preferably, the surface modifier comprises stearic acid and / or calcium lignosulfonate.

[0017] Preferably, the solvent comprises ethanol and / or water.

[0018] Preferably, the volume ratio of the total volume of the alumina powder, the surface modifier and the stabilizer to the volume of the solvent is 0.5-1.2:1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1 or 1.2:1, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0019] Preferably, the rotation speed of the ball mill is 100-500 r / min, for example, it can be 100 r / min, 120 r / min, 150 r / min, 180 r / min, 200 r / min, 220 r / min, 250 r / min, 280 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min or 500 r / min, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0020] Preferably, the time of the ball mill is 1-20 h, for example, it can be 1 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h or 20 h, etc.

[0021] Preferably, the temperature of the drying is 50-100℃, for example, it can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0022] Preferably, the temperature of the heating and stirring in step (1) is 60-260℃, for example, it can be 60℃, 76℃, 92℃, 105℃, 125℃, 135℃, 155℃, 165℃, 185℃, 200℃, 210℃, 250℃ or 260℃, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0023] Preferably, the time of the heating stirring is 30-240 min, for example, it can be 30 min, 55 min, 75 min, 100 min, 125 min, 145 min, 170 min, 195 min, 215 min or 240 min, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0024] Preferably, the mass ratio of the binder to the first mixture is 1:3-4.5, for example, it can be 1:3, 1:3.1, 1:3.2, 1:3.5, 1:3.8, 1:4.0, 1:4.2 or 1:4.5, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0025] Preferably, the binder comprises any one or a combination of at least two of stearic acid, polyethylene glycol, phenolic resin, epoxy resin, ethyl cellulose, polystyrene, polypropylene, polyethylene, polyvinyl alcohol, polyvinyl butyral or paraffin wax, wherein a typical but non-limiting combination is a combination of polyethylene glycol and phenolic resin, a combination of epoxy resin and phenolic resin, a combination of polyethylene glycol and epoxy resin, a combination of ethyl cellulose and phenolic resin, a combination of polyethylene glycol and ethyl cellulose.

[0026] Preferably, the pressure of the pressure stirring is 10-120 MPa, for example, it can be 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 80 MPa, 100 MPa, 110 MPa or 120 MPa, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0027] Preferably, the time of the pressure stirring is 1-10 h, for example, it can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0028] Preferably, the cooling in step (2) is cooling to room temperature.

[0029] Preferably, the particle size of the granular material obtained after the crushing is 1-10 mm, for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0030] Preferably, the nozzle size of the additive manufacturing is 0.05-3mm, for example, it can be 0.05mm, 0.38mm, 0.71mm, 1.04mm, 1.37mm, 1.69mm, 2.02mm, 2.35mm, 2.68mm or 3mm, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0031] Preferably, the layer thickness of the additive manufacturing is 0.05-0.35mm, for example, it can be 0.05mm, 0.09mm, 0.12mm, 0.15mm, 0.19mm, 0.22mm, 0.25mm, 0.29mm, 0.32mm or 0.35mm, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0032] Preferably, the printing speed of the additive manufacturing is 5-100mm / s, for example, it can be 5mm / s, 16mm / s, 27mm / s, 37mm / s, 48mm / s, 58mm / s, 69mm / s, 79mm / s, 90mm / s or 100mm / s, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0033] Preferably, the feeding flow rate of the additive manufacturing is 70-100%, for example, it can be 70%, 74%, 77%, 80%, 84%, 87%, 90%, 94%, 97% or 100%, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0034] Preferably, step (2) further comprises polishing the surface of the shaped workpiece.

[0035] Preferably, the surface roughness Ra after polishing is 0.1-1.6, for example, it can be 0.1, 0.2, 0.3, 0.5, 0.8, 1.0, 1.1, 1.5 or 1.6, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0036] Preferably, the debinding method in step (3) comprises solvent debinding and / or thermal debinding.

[0037] Preferably, the solvent used in the solvent debinding comprises any one or a combination of at least two of water, ethanol, n-heptane, kerosene, diesel oil or edible oil, wherein the typical but non-limiting combinations are the combination of water and ethanol, the combination of n-heptane and ethanol, the combination of water and n-heptane, the combination of kerosene and ethanol, the combination of edible oil and ethanol.

[0038] Preferably, the heat debinding comprises heating to a first temperature at a first heating rate for a first time, heating to a second temperature at a second heating rate for a second time, heating to a third temperature at a third heating rate for a third time, and heating to a fourth temperature at a fourth heating rate for a fourth time.

[0039] Preferably, the first heating rate is 0.2-5℃ / min, for example, it can be 0.2℃ / min, 0.74℃ / min, 1.27℃ / min, 1.8℃ / min, 2.34℃ / min, 2.87℃ / min, 3.4℃ / min, 3.94℃ / min, 4.47℃ / min or 5℃ / min, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0040] Preferably, the first temperature is 60-100℃, for example, it can be 60℃, 65℃, 69℃, 74℃, 78℃, 83℃, 87℃, 92℃, 96℃ or 100℃, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0041] Preferably, the first time is 30min-10h, for example, it can be 30min, 40min, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0042] Preferably, the second heating rate is 0.2-5℃ / min, for example, it can be 0.2℃ / min, 0.74℃ / min, 1.27℃ / min, 1.8℃ / min, 2.34℃ / min, 2.87℃ / min, 3.4℃ / min, 3.94℃ / min, 4.47℃ / min or 5℃ / min, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0043] Preferably, the second temperature is 180-220℃, for example, it can be 180℃, 185℃, 189℃, 194℃, 198℃, 203℃, 207℃, 212℃, 216℃ or 220℃, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0044] Preferably, the second time is 30min-12h, for example, it can be 30min, 40min, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or 12h, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0045] Preferably, the third temperature is 380 to 420℃, for example, it can be 380℃, 385℃, 389℃, 394℃, 398℃, 403℃, 407℃, 412℃, 416℃, or 420℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0046] Preferably, the third temperature is 380 to 420℃, for example, it can be 380℃, 385℃, 389℃, 394℃, 398℃, 403℃, 407℃, 412℃, 416℃, or 420℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0047] Preferably, the third time is 30 min to 12 h, for example, it can be 30 min, 40 min, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, or 12 h, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0048] Preferably, the third temperature is 380 to 420℃, for example, it can be 380℃, 385℃, 389℃, 394℃, 398℃, 403℃, 407℃, 412℃, 416℃, or 420℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0049] Preferably, the fourth temperature is 550 to 600℃, for example, it can be 550℃, 556℃, 562℃, 567℃, 573℃, 578℃, 584℃, 589℃, 595℃, or 600℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0050] Preferably, the fourth time is 30 min to 8 h, for example, it can be 30 min, 40 min, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, or 8 h, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0051] Preferably, the nitrogen element-containing condition in step (3) includes any one or a combination of at least two of surface coating with a nitrogen element, introduction of nitrogen gas, or placement in a compound containing a nitrogen element.

[0052] Preferably, the temperature rising rate of the sintering process is 0.5-10℃ / min, for example, it can be 0.5℃ / min, 1.6℃ / min, 2.7℃ / min, 3.7℃ / min, 4.8℃ / min, 5.8℃ / min, 6.9℃ / min, 7.9℃ / min, 9℃ / min or 10℃ / min, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0053] Preferably, the final temperature of the sintering process is 1200-2100℃, for example, it can be 1200℃, 1300℃, 1400℃, 1500℃, 1600℃, 1700℃, 1800℃, 1900℃, 2000℃ or 2100℃, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0054] The temperature of the sintering process in the present application is too high, which will cause the deformation of the ceramic substrate, and the temperature of the sintering process is too low, which will cause the difficulty in generating AlN.

[0055] Preferably, the sintering process is kept at the final temperature for 1-8h, for example, it can be 1h, 1.8h, 2.6h, 3.4h, 4.2h, 4.9h, 5.7h, 6.5h, 7.3h or 8h, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0056] As a preferred technical solution of the present application, the method comprises the following steps:

[0057] (1) mixing alumina powder, surface modifier, stabilizer and solvent, ball milling at a speed of 100-500r / min for 1-20h, the mass ratio of the alumina powder, surface modifier and stabilizer is 15-35:1:1-3, the volume ratio of the total volume of the alumina powder, surface modifier and stabilizer to the volume of the solvent is 0.5-1.2:1, and the time is 1-20h; to obtain a first mixture;

[0058] The first mixture is heated and stirred at 60-200℃ for 30-240min, and then mixed with a binder and subjected to pressure stirring at a pressure of 10-120MPa for 1-10h to obtain a second mixture;

[0059] The mass ratio of the binder to the first mixture is 1:3-4.5;

[0060] (2) the second mixture is sequentially cooled to room temperature and crushed to obtain granular materials with a particle size of 1-10 mm; the alumina particles are subjected to additive manufacturing, with a nozzle size of 0.05-3 mm, a layer thickness of 0.05-0.35 mm, a printing speed of 5-100 mm / s, and a feed flow of 70-100%, to obtain a shaped workpiece; and the surface of the shaped workpiece is polished to make the surface roughness Ra of the polished surface 0.1-1.6;

[0061] (3) the shaped workpiece is subjected to degreasing to obtain a degreased workpiece, which is subjected to sintering treatment under the condition of containing nitrogen element at a temperature rising rate of 0.5-10 ℃ / min to 1200-2100 ℃, and is kept at the final temperature for 1-8 h, to obtain an Al2O3-AlN in-situ composite ceramic.

[0062] In a second aspect, the present application provides an Al2O3-AlN in-situ composite ceramic, which is prepared by the method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing in the first aspect.

[0063] Preferably, the content of AlN in the Al2O3-AlN in-situ composite ceramic is 40-100%, for example, can be 40%, 47%, 54%, 60%, 67%, 74%, 80%, 87%, 94%, or 100%, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0064] Preferably, the content of Al2O3 in the Al2O3-AlN in-situ composite ceramic is 0.1-20%, for example, can be 0.1%, 2.4%, 4.6%, 6.8%, 9%, 11.2%, 13.4%, 15.6%, 17.8%, or 20%, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0065] Preferably, the thickness of the Al2O3-AlN in-situ composite ceramic is 500 nm-5 mm, for example, can be 500 nm, 1000 nm, 1500 nm, 2000 nm, 3000 nm, 5000 nm, 1 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, or 5.0 mm, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0066] In a third aspect, the present application provides an application of the Al2O3-AlN in-situ composite ceramic in the second aspect to a ceramic substrate for electronic packaging.

[0067] Compared with the prior art, the present application has at least the following beneficial effects:

[0068] (1) The method for preparing Al2O3-AlN in-situ composite ceramic by additive manufacturing provided by the application is simple to operate and low in cost;

[0069] (2) The method for preparing Al2O3-AlN in-situ composite ceramic by additive manufacturing provided by the application improves the problem that the thermal expansion coefficients of the Al2O3-AlN in-situ composite ceramic and the chip are inconsistent;

[0070] (3) The interface bonding strength of Al2O3 and AlN in the Al2O3-AlN in-situ composite ceramic is high, which is conducive to reducing the probability of damage of the substrate in use. BRIEF DESCRIPTION OF DRAWINGS

[0071] Figure 1 is an SEM diagram of the Al2O3-AlN in-situ composite ceramic prepared in Example 1 of the application.

[0072] Figure 2 is a whole structure diagram of the Al2O3-AlN in-situ composite ceramic prepared in Example 1 of the application. DETAILED DESCRIPTION

[0073] The technical solutions of the application will be further described below in combination with the drawings and through specific embodiments.

[0074] The application will be further described below. However, the following examples are only simple examples of the application and do not represent or limit the protection scope of the application, and the protection scope of the application is subject to the claims.

[0075] Example 1

[0076] The embodiment provides a method for preparing Al2O3-AlN in-situ composite ceramic by additive manufacturing, and the method comprises the following steps:

[0077] (1) 100 g of alumina powder, 2.5 g of stearic acid, 5 g of zirconium oxide and ethanol are mixed, the total volume of the alumina powder, the stearic acid and the zirconium oxide and the volume ratio of the ethanol agent are 1:1, and the mixture is placed in a ball mill tank and sealed, and then ball milling is performed at a speed of 256 r / min for 2 h; the powder after ball milling is placed in a drying box at 60 DEG C and dried for 2 h to obtain a first mixture;

[0078] The roller of the heating and stirring device is heated to 160 DEG C, 107.5 g of the first mixture is added to the roller and stirred for 30 min, and then 10.75 g of paraffin, 5 g of high-density polyethylene (HDPE), 3.75 g of thermoplastic phenolic resin (Phenolic Resin) and 2 g of polyethylene glycol (n=600) are mixed into the first mixture, and then the mixture is subjected to pressure stirring at a pressure of 30 MPa for 6 h (maintained at the original roller temperature) to obtain a second mixture;

[0079] (2) the second mixture is cooled to room temperature in sequence and cut into 2-3 mm granular materials; the alumina particles are subjected to additive manufacturing, a workpiece is prepared according to a slicing model of a solid, a machine heating module heats and extrudes alumina feedstock to make the workpiece, the nozzle size is 0.5 mm, the layer thickness is 0.2 mm, the printing speed is 20 mm / s, and the feed flow is 100%, to obtain a formed workpiece; the surface of the formed workpiece is polished, and the surface roughness Ra of the polished surface is 0.2;

[0080] (3) the formed workpiece is placed into a heat treatment furnace, heated to 80℃ at 0.5℃ / min for 5h, continuously heated to 180℃ at 0.5℃ / min for 10h, continuously heated to 260℃ at 0.5℃ / min for 8h, and continuously heated to 380℃ at 0.5℃ / min for 8h. After being cooled to room temperature state at a cooling rate of 1℃ / min and being lowered by 70℃, the formed workpiece is debinded, wrapped with graphite paper, placed into a carbon atmosphere furnace, vacuumized, and then nitrogen is introduced, heated to 1800℃ at a heating rate of 5℃ / min, and sintered at the final temperature for 2h to obtain the Al2O3-AlN in-situ composite ceramic.

[0081] The overall structure of the Al2O3-AlN in-situ composite ceramic prepared in this example is shown in Figure 2 , and the SEM image thereof is shown in Figure 1 . As can be seen from the SEM image, the surface microstructure of the Al2O3-AlN in-situ composite ceramic is uniformly distributed, and no obvious pores are found on the surface, and the overall structure is relatively dense.

[0082] Example 2

[0083] The present example provides a method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing, which comprises the following steps:

[0084] (1) mixing alumina powder 125g, stearic acid 2.5g, zirconia 5g and ethanol, the total volume of the alumina powder, stearic acid and zirconia and the volume of the ethanol agent are in a ratio of 1.2:1, and then placing them into a ball milling jar, sealing and ball milling at a speed of 128r / min for 20h, and then drying the ball-milled powder in a drying box at 65℃ for 3h to obtain a first mixture;

[0085] Heat the roller of the stirring device to 200℃, add 132.5g of the first mixture to the roller, stir for 15min, and mix in the binder (13g of paraffin, 7g of high-density polyethylene (HDPE), 6g of thermoplastic phenolic resin, and 4g of polyethylene glycol (n=600)), and then pressurize and stir for 3h at a pressure of 50MPa (maintained at the original roller temperature) to obtain a second mixture;

[0086] (2) The second mixture is cooled to room temperature and cut into 3-5mm granules in sequence; the alumina particles are subjected to additive manufacturing, a machine heating module heats and extrudes the alumina feedstock to make a workpiece according to a slice model of a solid, the nozzle size is 3mm, the layer thickness is 0.35mm, the printing speed is 50mm / s, and the feed flow is 70%, to obtain a formed workpiece; the surface of the formed workpiece is polished, and the surface roughness Ra after polishing is 1.0;

[0087] (3) The formed workpiece is placed in a heat treatment furnace, heated to 100℃ at a rate of 5℃ / min and held for 3h, then heated to 190℃ at a rate of 0.2℃ / min and held for 8h, then heated to 420℃ at a rate of 0.5℃ / min and held for 12h, and then heated to 600℃ at a rate of 5℃ / min and held for 1h. After cooling to room temperature at a rate of 2℃ / min and dropping by 78℃, the formed workpiece is debound, urea is placed around the debound workpiece, and the workpiece and urea are placed in a furnace, heated to 2100℃ at a rate of 10℃ / min, and held at the final temperature for 1h for sintering treatment, to obtain an Al2O3-AlN in-situ composite ceramic.

[0088] Example 3

[0089] The present embodiment provides a method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing, which comprises the following steps:

[0090] (1) Mix 75g of alumina powder, 2g of stearic acid, 4g of zirconia, and ethanol, the total volume of the alumina powder, stearic acid, and zirconia to the volume of the ethanol is 0.5:1, place them in a ball mill jar, seal the jar, and perform ball milling at a speed of 384r / min for 1h, then dry the milled powder in a drying box at 65℃ for 4h to obtain a first mixture;

[0091] Heat the roller of the stirring device to 100℃, add 81g of the first mixture to the roller, stir for 60min, and mix in the binder (6g of polyethylene glycol (n=600), 5g of polyethylene glycol (n=2000), 5g of low-density polyethylene (LDPE), and 4g of high-density polyethylene (HDPE)), and then pressurize and stir for 10h at a pressure of 20MPa (maintained at the original roller temperature) to obtain a second mixture;

[0092] (2) the second mixture is cooled to room temperature in sequence and cut into 1-2 mm granular materials; the alumina particles are subjected to additive manufacturing, a workpiece is prepared by heating and extruding alumina feedstock according to a slicing model of the entity, a nozzle size is 0.05 mm, a layer thickness is 0.05 mm, a printing speed is 20 mm / s, and a feeding flow is 80%, to obtain a formed workpiece; the surface of the formed workpiece is polished, and a surface roughness Ra of the polished surface is 0.5;

[0093] (3) the formed workpiece is subjected to ethanol solvent degreasing (the sample is placed in a beaker containing an ethanol solvent, and is heated to 52℃ in a water bath or oil bath for 5 h), the obtained workpiece after degreasing is wrapped with graphite paper and placed in a carbon atmosphere furnace, vacuum is drawn, nitrogen is introduced, the temperature is raised to 1400℃ at a rate of 0.5℃ / min, and sintering treatment is performed at the final temperature for 5 h, to obtain an Al2O3-AlN in-situ composite ceramic.

[0094] Example 4

[0095] The present embodiment provides a method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing, wherein the mass ratio of the alumina powder to the zirconia is 50:1, and the rest is the same as in Example 1, which will not be repeated here.

[0096] In the present embodiment, the AlN content in the subsequently obtained in-situ composite ceramic is very low, only within 10%, and the thermal conductivity is only 35 W / (m·k).

[0097] Example 5

[0098] The present embodiment provides a method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing, wherein the mass ratio of the alumina powder to the zirconia is 10:1, and the rest is the same as in Example 1, which will not be repeated here.

[0099] In the present embodiment, the in-situ composite ceramic obtained subsequently contains impurities such as ZrN and ZrNO, resulting in a thermal conductivity of only 127 W / (m·k).

[0100] As can be seen from Examples 1 and 4-5, by controlling the mass ratio of the alumina powder to the zirconia within a specific range, the composition of the in-situ composite ceramic and the thermal conductivity of the final composite ceramic are more favorably ensured.

[0101] Example 6

[0102] The present embodiment provides a method for preparing an Al2O3-AlN in-situ composite ceramic by additive manufacturing, wherein the final temperature in step (3) is 2200℃, and the rest is the same as in Example 1, which will not be repeated here.

[0103] The workpiece surface of the embodiment is obviously curved and deformed due to the excessively high final temperature, which affects the overall structure.

[0104] Example 7

[0105] The embodiment provides a method for preparing Al2O3-AlN in-situ composite ceramics by additive manufacturing, which is the same as example 1 except that the final temperature in step (3) is 1000 DEG C, and details are not repeated here.

[0106] In the embodiment, the workpiece surface is loose, the strength is low, and it is difficult to form AlN, and the thermal conductivity is only 25 W / (m·k).

[0107] It can be seen from examples 1 and 6-7 that the method for preparing Al2O3-AlN in-situ composite ceramics by additive manufacturing provided by the application can more favorably improve the strength and thermal conductivity of the product only when the final temperature is controlled in a specific range.

[0108] Comparative example 1

[0109] The comparative example provides a method for preparing Al2O3-AlN in-situ composite ceramics, which is the same as example 1 except that the sintering treatment in step (3) is not performed, and details are not repeated here.

[0110] In the comparative example, the workpiece surface has obvious powder falling phenomenon, is loose and has extremely low strength, and cannot form AlN, and the thermal conductivity is only 22 W / (m·k).

[0111] Comparative example 2

[0112] The comparative example provides a method for preparing Al2O3-AlN in-situ composite ceramics, which is the same as example 1 except that nitrogen is not introduced in the sintering treatment in step (3), and details are not repeated here.

[0113] The ceramic phase composition of the comparative example is Al2O3, no AlN is generated, and the thermal conductivity is only 25 W / (m·k).

[0114] It can be seen from examples 1 and comparative examples 1-2 that the nitrogen-containing gas source or the nitrogen-containing compound can promote the generation of AlN phase, and the thermal conductivity of the Al2O3-AlN in-situ composite ceramics synthesized by the method is obviously increased relative to Al2O3, which proves that it has the ability to increase the heat dissipation of the chip packaging substrate. From the interface analysis of the microstructure, the interface of the Al2O3-AlN in-situ composite ceramics has no obvious pores and cracks, which proves that the Al2O3-AlN composite ceramics and Al2O3 have good interface bonding.

[0115] Comparative example 3

[0116] The comparative example provides a method for preparing Al2O3-AlN in-situ composite ceramic, which is the same as that of example 1 except that the pressure stirring in step (1) and the cooling and crushing in step (2) are not performed, and the average particle size of the granular material obtained by ball milling after directly mixing the binder is 2-3 mm, which is not described here.

[0117] Test method: The cross-sectional thickness of the Al2O3-AlN in-situ composite ceramic is observed and measured by scanning electron microscopy, the Al2O3 content and the AlN content in the Al2O3-AlN in-situ composite ceramic are semi-quantitatively analyzed by XRD, the thermal conductivity of the Al2O3-AlN in-situ composite ceramic is tested by the flat plate method, and whether there are obvious cracks and pores and other defects in the Al2O3-AlN interface bonding of the Al2O3-AlN in-situ composite ceramic is observed by scanning electron microscopy.

[0118] The test results of the above examples and comparative examples are shown in Table 1.

[0119] Table 1

[0120]

[0121]

[0122] From Table 1, the following points can be seen:

[0123] (1) As can be seen from examples 1-3, the method for preparing Al2O3-AlN in-situ composite ceramic by additive manufacturing provided by the present application can prepare Al2O3-AlN in-situ composite ceramic with excellent performance, which has strong bonding strength and a thermal conductivity of more than 160 W / (m·k);

[0124] (2) As can be seen from example 1 and comparative example 3, the steps of ball milling, drying, heating and stirring, pressure stirring, cooling and crushing are combined in the present application, and these steps play a role in a specific order, which can obtain ceramic products with higher bonding strength and higher density.

[0125] The above examples illustrate the detailed structural features of the present application, but the present application is not limited to the above detailed structural features, i.e. it does not mean that the present application must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present application, equivalent replacement of the components selected by the present application, addition of auxiliary components, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing Al2O3-AlN in-situ composite ceramics by additive manufacturing, characterized in that, The method includes the following steps: (1) Alumina powder, surface modifier, stabilizer and solvent are mixed, ball-milled and dried in sequence to obtain a first mixture; the first mixture is heated and stirred, and a binder is mixed in and then stirred under pressure to obtain a second mixture; (2) The second mixture is cooled and crushed in sequence to obtain granules; the granules are then additively manufactured to obtain molded workpieces; (3) The molded workpiece is degreased, and the degreased workpiece is placed in a carbon atmosphere furnace or urea is placed around the degreased workpiece before it is placed in the furnace. It is then sintered under nitrogen-containing conditions to obtain Al2O3-AlN in-situ composite ceramic. In step (1), the mass ratio of alumina powder, surface modifier and stabilizer is 15~35:1:1~3; the stabilizer includes zirconium oxide.

2. The method according to claim 1, characterized in that, The surface modifiers include stearic acid and / or calcium lignosulfonate.

3. The method according to claim 1, characterized in that, The solvent includes ethanol and / or water.

4. The method according to claim 1, characterized in that, The volume ratio of the total volume of the alumina powder, surface modifier and stabilizer to the volume of the solvent is 0.5~1.2:

1.

5. The method according to claim 1, characterized in that, The ball mill rotates at a speed of 100~500 r / min.

6. The method according to claim 1, characterized in that, The ball milling time is 1 to 20 hours.

7. The method according to claim 1, characterized in that, The drying temperature is 50~100℃.

8. The method according to claim 1 or 2, characterized in that, The heating and stirring temperature in step (1) is 60~260℃.

9. The method according to claim 1, characterized in that, The heating and stirring time is 30~240 minutes.

10. The method according to claim 1, characterized in that, The mass ratio of the adhesive to the first mixture is 1:3 to 4.

5.

11. The method according to claim 1, characterized in that, The binder comprises any one or a combination of at least two of the following: stearic acid, polyethylene glycol, phenolic resin, epoxy resin, ethyl cellulose, polystyrene, polypropylene, polyethylene, polyvinyl alcohol, polyvinyl butyral, or paraffin.

12. The method according to claim 1, characterized in that, The pressure of the pressurized stirring is 10~120MPa.

13. The method according to claim 1, characterized in that, The pressurized stirring time is 1 to 10 hours.

14. The method according to any one of claims 1 to 3, characterized in that, The cooling mentioned in step (2) is cooling to room temperature.

15. The method according to claim 1, characterized in that, The particle size of the granules obtained after crushing is 1~10mm.

16. The method according to claim 1, characterized in that, The nozzle size of the additive manufacturing is 0.05~3mm.

17. The method according to claim 1, characterized in that, The thickness of the additive manufacturing layer is 0.05~0.35mm.

18. The method according to claim 1, characterized in that, The printing speed of the additive manufacturing is 5~100mm / s.

19. The method according to claim 1, characterized in that, The feed flow rate for additive manufacturing is 70-100%.

20. The method according to any one of claims 1 to 4, characterized in that, Step (2) also includes: polishing the surface of the molded workpiece.

21. The method according to claim 20, characterized in that, The surface roughness Ra after polishing is 0.1~1.

6.

22. The method according to any one of claims 1 to 5, characterized in that, The degreasing method described in step (3) includes solvent degreasing and / or thermal degreasing.

23. The method according to claim 22, characterized in that, The solvent used for solvent degreasing includes any one or a combination of at least two of the following: water, ethanol, n-heptane, kerosene, diesel oil, or edible oil.

24. The method according to claim 22, characterized in that, The thermal degreasing process includes heating to a first temperature at a first heating rate and holding for a first time, then heating to a second temperature at a second heating rate and holding for a second time, then heating to a third temperature at a third heating rate and holding for a third time, and then heating to a fourth temperature at a fourth heating rate and holding for a fourth time.

25. The method according to claim 24, characterized in that, The first heating rate is 0.2~5℃ / min.

26. The method according to claim 24, characterized in that, The first temperature is 60~100℃.

27. The method according to claim 24, characterized in that, The first time period is 30 minutes to 10 hours.

28. The method according to claim 24, characterized in that, The second heating rate is 0.2~5℃ / min.

29. The method according to claim 24, characterized in that, The second temperature is 180~220℃.

30. The method according to claim 24, characterized in that, The second time is 30 minutes to 12 hours.

31. The method according to claim 24, characterized in that, The third heating rate is 0.2~5℃ / min.

32. The method according to claim 24, characterized in that, The third temperature is 380~420℃.

33. The method according to claim 24, characterized in that, The third time period is 30 minutes to 12 hours.

34. The method according to claim 24, characterized in that, The fourth heating rate is 0.2~5℃ / min.

35. The method according to claim 24, characterized in that, The fourth temperature is 550~600℃.

36. The method according to claim 24, characterized in that, The fourth time period is 30 minutes to 8 hours.

37. The method according to any one of claims 1 to 6, characterized in that, The conditions for nitrogen-containing elements mentioned in step (3) include: coating the surface with nitrogen-containing elements, introducing nitrogen gas, or placing a nitrogen-containing compound, or a combination of at least two of these.

38. The method according to claim 1, characterized in that, The heating rate of the sintering process is 0.5~10℃ / min.

39. The method according to claim 1, characterized in that, The final temperature of the sintering process is 1200~2100℃.

40. The method according to claim 1, characterized in that, The sintering process involves holding the sample at the final temperature for 1 to 8 hours.

41. The method according to claim 1, characterized in that, The method includes the following steps: (1) Mix alumina powder, surface modifier, stabilizer and solvent, and ball mill at a speed of 100~500 r / min for 1~20 h, wherein the mass ratio of alumina powder, surface modifier and stabilizer is 15~35:1:1~3, the volume ratio of the total volume of alumina powder, surface modifier and stabilizer to the volume of solvent is 0.5~1.2:1, and the time is 1~20 h; to obtain the first mixture; The first mixture is heated and stirred at 60~200℃ for 30~240 min, and then mixed with a binder and stirred under pressure of 10~120MPa for 1~10 h to obtain the second mixture; The mass ratio of the adhesive to the first mixture is 1:3~4.5; (2) The second mixture is cooled to room temperature and crushed in sequence to obtain granules with a particle size of 1~10mm; the granules are then processed by additive manufacturing with a nozzle size of 0.05~3mm, a layer thickness of 0.05~0.35mm, a printing speed of 5~100mm / s, and a feed flow rate of 70~100% to obtain a molded workpiece. The surface of the molded workpiece is polished to achieve a surface roughness Ra of 0.1 to 1.

6. (3) The molded workpiece is degreased, and the degreased workpiece is placed in a carbon atmosphere furnace or urea is placed around the degreased workpiece before it is placed in the furnace. Under nitrogen-containing conditions, the temperature is raised to 1200~2100℃ at a heating rate of 0.5~10℃ / min, and sintered at the final temperature for 1~8h to obtain Al2O3-AlN in-situ composite ceramic.

42. An Al2O3-AlN in-situ composite ceramic, characterized in that, The Al2O3-AlN in-situ composite ceramic is prepared by the additive manufacturing method described in any one of claims 1 to 41.

43. The Al2O3-AlN in-situ composite ceramic according to claim 42, characterized in that, The AlN content in the Al2O3-AlN in-situ composite ceramic is 40~100%.

44. The Al2O3-AlN in-situ composite ceramic according to claim 42, characterized in that, The Al2O3 content in the Al2O3-AlN in-situ composite ceramic is 0.1~20%.

45. The Al2O3-AlN in-situ composite ceramic according to claim 42, characterized in that, The thickness of the Al2O3-AlN in-situ composite ceramic is 500 nm to 5 mm.

46. ​​The application of the Al2O3-AlN in-situ composite ceramic according to any one of claims 42 to 45 in a ceramic substrate for electronic packaging.

Images