A boron nitride ceramic material, its preparation method and application

Abstract

The present invention discloses a boron nitride ceramic material, a preparation method thereof and an application thereof. The preparation method comprises the following steps: taking a mixed powder containing boron nitride and boric acid, performing cold sintering and annealing to obtain the boron nitride ceramic material. In the preparation method of the present invention, cold sintering treatment is carried out before annealing, which is beneficial to improving the densification of the boron nitride ceramic material, making the obtained ceramic material have few pores and high density, good thermal conductivity of the ceramic material, and at the same time, the obtained boron nitride ceramic material of the present invention has the characteristic of low dielectric constant.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and particularly relates to a boron nitride ceramic material, a preparation method thereof, and an application thereof. Background Art

[0002] Driven by the requirements of microwave communication technology, electronic devices are developing towards the direction of integration, high energy efficiency, and high reliability, and the requirements for the thermal conductivity of the materials of electronic devices are getting higher and higher. For example, for packaging substrates, the power density of electronic devices is increasing, the heat generation per unit of the substrate is increasing, and the heat dissipation problem has become one of the core problems restricting the further development of communication technology. At present, there are various substrate materials, including organic substrate materials, ceramic materials, etc. Among them, the preparation methods of ceramic materials include high-temperature sintering, plasma sintering, etc. However, the ceramic materials prepared in the related art have poor densification and poor thermal conductivity. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a preparation method of a boron nitride ceramic material, and the obtained ceramic material has good densification and excellent thermal conductivity.

[0004] The present invention also provides a boron nitride ceramic material.

[0005] The present invention also provides a packaging substrate.

[0006] The present invention also provides an electronic device.

[0007] The present invention also provides an application of the above-mentioned boron nitride ceramic material.

[0008] In the first aspect of the present invention, a preparation method of a boron nitride ceramic material is provided, including the following steps: taking a mixed powder containing boron nitride and boric acid, and obtaining the boron nitride ceramic material through cold sintering and annealing.

[0009] The preparation method of the boron nitride ceramic material according to the embodiments of the present invention has at least the following beneficial effects:

[0010] In the present invention, cold sintering treatment is carried out before annealing, which is beneficial to improving the densification of the boron nitride ceramic material, making the obtained boron nitride ceramic material have few pores and high density, and the ceramic material has good thermal conductivity. At the same time, the boron nitride ceramic material obtained by the present invention has the characteristics of low dielectric constant and low dielectric loss. The boron nitride ceramic material can be applied to power electronic packaging integration technologies such as high-frequency and high-speed circuit substrates and packaging substrates, and can also be applied to high-frequency communication system technologies such as 5G technology, Internet of Things, and satellite communication.

[0011] In addition, the raw materials of the present invention are inexpensive, the process method is simple, easy to control, and the process repeatability is good, having broad application prospects.

[0012] In some embodiments of the present invention, in the mixed powder, the boron nitride includes hexagonal boron nitride (h-BN).

[0013] h-BN is commonly known as "white graphite". It has a layered structure similar to graphite, with high thermal stability, high chemical stability, excellent thermal conductivity, and good high-temperature insulation. However, since h-BN is a six-membered ring network formed by alternating B and N atoms and bonded by covalent bonds, and the layers are connected by van der Waals forces, it is difficult to sinter densely.

[0014] In the present invention, cold sintering treatment is carried out before annealing, which is beneficial to the sintering of h-BN and the improvement of the densification of the ceramic material, making the obtained ceramic material have few pores, high density, and good thermal conductivity. First, h-BN powder and H3BO3 are used as raw materials to prepare H3BO3-h-BN mixed powder, then H3BO3-h-BN composite ceramics are prepared by cold sintering, and finally the H3BO3-h-BN composite ceramics are annealed to obtain a low-temperature sintered and dense boron nitride ceramic material. In addition, the raw materials of the present invention include commercial hexagonal boron nitride (h-BN) powder and H3BO3 powder. The raw materials are inexpensive, the process method is simple, easy to control, and the process repeatability is good, having broad application prospects.

[0015] In some embodiments of the present invention, the sintering temperature of the cold sintering is 10-80 °C.

[0016] In some preferred embodiments of the present invention, the sintering temperature of the cold sintering is 25-65 °C.

[0017] In some embodiments of the present invention, the sintering time of the cold sintering is 5-200 min.

[0018] In some preferred embodiments of the present invention, the sintering time of the cold sintering is 10-120 min.

[0019] In some more preferred embodiments of the present invention, the sintering time of the cold sintering is 30-90 min.

[0020] In some embodiments of the present invention, the pressure of the cold sintering is 100-600 MPa.

[0021] In some preferred embodiments of the present invention, the pressure of the cold sintering is 200-500 MPa.

[0022] In some embodiments of the present invention, in the mixed powder, the volume ratio of the boron nitride to the boric acid is (5 - 110):(5 - 110).

[0023] In some preferred embodiments of the present invention, in the mixed powder, the volume ratio of the boron nitride to the boric acid is (10 - 90):(10 - 90).

[0024] In some embodiments of the present invention, the annealing is carried out in an atmosphere containing ammonia gas.

[0025] In some preferred embodiments of the present invention, the annealing is carried out in an atmosphere of ammonia gas.

[0026] In some preferred embodiments of the present invention, the annealing temperature is 700 - 1100 °C, and the annealing time is 0.5 - 8 h.

[0027] In some preferred embodiments of the present invention, the annealing temperature is 850 - 950 °C, and the annealing time is 2 - 6 h.

[0028] In some preferred embodiments of the present invention, in the annealing step, the heating rate is 5 - 15 °C / min.

[0029] In some preferred embodiments of the present invention, the atmosphere containing ammonia gas is an atmosphere containing ammonia gas and an inert gas.

[0030] In some embodiments of the present invention, the annealing includes: heating at a rate of 5 - 15 °C / min in an environment containing ammonia gas, and annealing at 850 - 950 °C for 2 - 6 h.

[0031] In some embodiments of the present invention, the preparation method includes the following steps: mixing the mixed powder with water to obtain mixture I, cold sintering, and annealing in an atmosphere containing ammonia gas to obtain the boron nitride ceramic material.

[0032] In some preferred embodiments of the present invention, in mixture I, the mass ratio of water to boric acid in the mixed powder is (5 - 20):(95 - 110).

[0033] In some preferred embodiments of the present invention, in mixture I, the volume ratio of boron nitride, boric acid, and water is (5 - 110):(5 - 110):(0.5 - 20), and more preferably (10 - 90):(10 - 90):(1 - 10).

[0034] In some embodiments of the present invention, the preparation method includes the following steps:

[0035] S1. Mix the mixed powder with water to obtain Mixture I.

[0036] S2. Cold sinter the Mixture I to obtain Material I.

[0037] S3. Anneal the Material I in an atmosphere containing ammonia to obtain the boron nitride ceramic material.

[0038] In some preferred embodiments of the present invention, the Material I is an H3BO3 - h - BN composite ceramic material.

[0039] In some embodiments of the present invention, the preparation method includes preparing the mixed powder, and the preparation of the mixed powder includes the following operations: Mix boron nitride and an aqueous solution containing boric acid, and dry to obtain the mixed powder. Preferably, the drying method is freeze - drying.

[0040] In some embodiments of the present invention, the preparation method includes preparing the mixed powder, and the preparation of the mixed powder includes the following operations: Mix boric acid with water, add boron nitride, dry, ball - mill, and grind to obtain the mixed powder.

[0041] In some preferred embodiments of the present invention, the average particle size of the boron nitride is 0.05 - 20 μm.

[0042] In some preferred embodiments of the present invention, the boron nitride includes hexagonal boron nitride (h - BN).

[0043] In some preferred embodiments of the present invention, the average particle size of the boric acid is 0.05 - 50 μm.

[0044] In some preferred embodiments of the present invention, the volume ratio of the boron nitride to the boric acid is (5 - 110):(5 - 110), more preferably (10 - 90):(10 - 90).

[0045] In some preferred embodiments of the present invention, the mass ratio of boric acid to water is (0.2 - 5):(100 - 300).

[0046] In some embodiments of the present invention, the preparation method includes preparing the mixed powder, and the preparation of the mixed powder includes the following operations:

[0047] S1 - 1. Mix boron nitride and an aqueous solution containing boric acid, and freeze - dry to obtain Mixture II.

[0048] S1 - 2. Using organic solvent I as the solvent, ball - mill, dry, grind, and sieve Mixture II to obtain the mixed powder.

[0049] In some preferred embodiments of the present invention, in step S1-2, the organic solvent I includes at least one of acetone, methyl ethyl ketone or hexanone.

[0050] Compared with water and alcohol in which H3BO3 powder is easily soluble, H3BO3 powder is hardly soluble in acetone. Using acetone as the ball-milling solvent, the ball-milling mixing effect is better.

[0051] In some preferred embodiments of the present invention, in step S1-2, zirconia balls are used as the ball-milling beads to ball-mill the mixture II.

[0052] In some preferred embodiments of the present invention, in step S1-2, in the ball-milling step, the ball-milling speed is 300-700 rpm, preferably 300-600 rpm.

[0053] In some preferred embodiments of the present invention, in step S1-2, in the ball-milling step, the ball-milling time is 2-6 h.

[0054] In some preferred embodiments of the present invention, in step S1-2, in the ball-milling step, the ball-to-material ratio is (2-6):1.

[0055] In some preferred embodiments of the present invention, in step S1-2, the drying temperature is 25-60 °C.

[0056] In some preferred embodiments of the present invention, in step S1-2, in the sieving step, the mesh number of the sieve is 40-200 mesh.

[0057] In a second aspect of the present invention, a boron nitride ceramic material is provided, and the boron nitride ceramic material is prepared by using the above preparation method.

[0058] The boron nitride ceramic material according to the embodiment of the present invention has at least the following beneficial effects: In the present invention, cold sintering treatment is carried out before annealing, which is beneficial to improving the densification of the ceramic material, so that the obtained boron nitride ceramic material has few pores, high density and good thermal conductivity. At the same time, the boron nitride ceramic material obtained in the present invention has the characteristics of low dielectric constant and low dielectric loss. The boron nitride ceramic material can be applied to power electronic packaging integration technologies such as high-frequency and high-speed circuit boards and packaging boards, and can also be applied to high-frequency communication system technologies such as 5G technology, Internet of Things and satellite communication.

[0059] In some embodiments of the present invention, the density of the boron nitride ceramic material is 2.0 g·cm -3 or more.

[0060] In some embodiments of the present invention, the thermal conductivity of the boron nitride ceramic material is 35 W·m -1 ·K -1 or more.

[0061] In some preferred embodiments of the present invention, the thermal conductivity of the boron nitride ceramic material is 39-60 W·m -1 ·K -1 .

[0062] In some embodiments of the present invention, the dielectric constant of the boron nitride ceramic material is 3.7-4.8, preferably 3.7-4.5.

[0063] In some embodiments of the present invention, the dielectric loss of the boron nitride ceramic material is (1-5)×10 -4 .

[0064] In some embodiments of the present invention, the purity of the boron nitride ceramic material is above 98%.

[0065] Wherein the purity of boron nitride is: the mass percentage of boron nitride in the boron nitride ceramic material.

[0066] In a third aspect of the present invention, a packaging substrate is proposed, and the packaging substrate includes the above-mentioned boron nitride ceramic material.

[0067] In a fourth aspect of the present invention, an electronic device is proposed, and the electronic device includes the above-mentioned boron nitride ceramic material.

[0068] In a fifth aspect of the present invention, an application of the above-mentioned boron nitride ceramic material in the preparation of electronic packaging devices or electronic integrated devices is proposed. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The present invention will be further described below with reference to the drawings and embodiments, wherein:

[0070] Figure 1 is the XRD pattern of the boron nitride ceramic material in Example 1 of the present invention;

[0071] Figure 2 is the infrared spectrum of the boron nitride ceramic material in Example 1 of the present invention;

[0072] Figure 3 is the Raman spectrum of the boron nitride ceramic material in Example 1 of the present invention;

[0073] Figure 4 is the microscopic test result diagram of the boron nitride ceramic material in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0074] The concept of the present invention and the resulting technical effects will be clearly and completely described below in conjunction with embodiments to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present invention.

[0075] For the experimental methods without specific conditions noted in the following examples, they are generally carried out according to the conventional conditions in the art or according to the conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are all raw materials and reagents that can be obtained from commercial channels such as the conventional market.

[0076] Example 1

[0077] This example discloses a boron nitride ceramic material, and its preparation process includes:

[0078] (Ⅰ) Take h-BN powder with an average particle size of 0.5 μm and H3BO3 powder with an average particle size of 50 μm (the volume ratio of h-BN powder to H3BO3 powder is 9:1). Mix the H3BO3 powder with water to obtain an H3BO3 aqueous solution (where the dosage ratio of H3BO3 powder to water is 2.5 g powder: 200 mL water). Disperse the h-BN powder evenly in the H3BO3 aqueous solution, and then perform freeze-drying to obtain H3BO3-h-BN mixed material Ⅰ (in powder form). Using acetone as the solvent and zirconia balls as the ball-milling beads, ball-mill and mix the H3BO3-h-BN mixed material Ⅰ evenly to obtain a mixed slurry; the ball-milling mixing time is 4 h, the ball-milling mixing speed is 600 rpm, and the ball-to-material ratio of ball-milling mixing is 2:1. Dry the mixed slurry in a forced-air drying oven at 60 °C, grind it, and sieve it through a 40-mesh sieve to obtain H3BO3-h-BN mixed powder.

[0079] (Ⅱ) Add deionized water (the mass of deionized water is 10% of the mass of H3BO3 powder) to the H3BO3-h-BN mixed powder, then use a mortar to grind it evenly, and let it stand at normal temperature and pressure for one day to obtain mixed material Ⅱ (in powder form). Add the mixed material Ⅱ into a mold, and then perform cold sintering at a pressure of 300 MPa and a sintering temperature of 60 °C for 30 min to obtain an H3BO3-h-BN composite ceramic material prepared by cold sintering. Place the H3BO3-h-BN composite ceramic material in a quartz boat, and then first introduce nitrogen into the tubular furnace for 20 min to remove the air in the tubular furnace, and then introduce ammonia for annealing treatment. Among them, the annealing temperature is 900 °C, the annealing time is 4 h, and the heating rate is 10 °C / min. As ammonia is introduced, the H3BO3 powder will react with ammonia to transform into BN. After the annealing is completed, cool it with the furnace to obtain the boron nitride ceramic material.

[0080] This embodiment also provides a packaging substrate, including the boron nitride ceramic material prepared in this embodiment.

[0081] This embodiment also provides an electronic device, including the boron nitride ceramic material prepared in this embodiment.

[0082] Example 2

[0083] This embodiment discloses a boron nitride ceramic material, and its preparation process includes:

[0084] (Ⅰ) Take h-BN powder with an average particle size of 1 μm, H3BO3 powder with an average particle size of 20 μm (the volume ratio of h-BN powder to H3BO3 powder is 8:2). Mix the H3BO3 powder with water to obtain an H3BO3 aqueous solution (the dosage ratio of H3BO3 powder to water is 2.5 g powder: 200 mL water). Disperse the h-BN powder evenly in the H3BO3 aqueous solution, and then perform freeze-drying to obtain the H3BO3-h-BN mixed material Ⅰ (as a powder). Using acetone as the solvent and zirconia balls as the ball-milling beads, ball-mill and mix the H3BO3-h-BN mixed material Ⅰ evenly to obtain a mixed slurry; the ball-milling mixing time is 4 h, the ball-milling mixing speed is 500 rpm, and the ball-to-material ratio of the ball-milling mixing is 5:1. Dry the mixed slurry in a forced-air drying oven at 40 °C, grind it, and sieve it through an 80-mesh sieve to obtain the H3BO3-h-BN mixed powder.

[0085] (Ⅱ) Add deionized water (the mass of deionized water is 10% of the mass of the H3BO3 powder) to the H3BO3-h-BN mixed powder, and then grind it evenly with a mortar and pestle, and let it stand at normal temperature and pressure for one day to obtain the mixed material Ⅱ (as a powder). Add the mixed material Ⅱ into a mold, and then perform cold sintering at a pressure of 200 MPa and a sintering temperature of 50 °C for 30 min to obtain the H3BO3-h-BN composite ceramic material prepared by cold sintering. Place the H3BO3-h-BN composite ceramic material in a quartz boat, and then first introduce nitrogen gas into the tubular furnace for 20 min to remove the air in the tubular furnace, and then introduce ammonia gas for annealing treatment. Among them, the annealing temperature is 900 °C, the annealing time is 4 h, and the heating rate is 10 °C / min. As the ammonia gas is introduced, the H3BO3 powder will react with the ammonia gas to transform into BN. After the annealing is completed, cool it with the furnace to obtain the boron nitride ceramic material.

[0086] This embodiment also provides a packaging substrate, including the boron nitride ceramic material prepared in this embodiment.

[0087] This embodiment also provides an electronic device, including the boron nitride ceramic material prepared in this embodiment.

[0088] Example 3

[0089] This example discloses a boron nitride ceramic material, and its preparation process includes:

[0090] (Ⅰ) Take h-BN powder with an average particle size of 3 μm and H3BO3 powder with an average particle size of 5 μm (the volume ratio of h-BN powder to H3BO3 powder is 7:3). Mix the H3BO3 powder with water to obtain an H3BO3 aqueous solution (the dosage ratio of H3BO3 powder to water is 2.5 g powder: 200 mL water). Disperse the h-BN powder evenly in the H3BO3 aqueous solution, and then perform freeze-drying to obtain H3BO3-h-BN mixed material Ⅰ (as powder). Using acetone as the solvent and zirconia balls as the ball-milling beads, ball-mill and mix the H3BO3-h-BN mixed material Ⅰ evenly to obtain a mixed slurry; among them, the ball-milling mixing time is 4 h, the ball-milling mixing rotation speed is 500 rpm, and the ball-to-material ratio of ball-milling mixing is 4:1. Dry the mixed slurry in a forced-air drying oven at 60 °C, grind it, and sieve it through a 120-mesh sieve to obtain H3BO3-h-BN mixed powder.

[0091] (Ⅱ) Add deionized water (the mass of deionized water is 10% of the mass of H3BO3 powder) to the H3BO3-h-BN mixed powder, then use a mortar to grind it evenly, and let it stand at normal temperature and pressure for one day to obtain mixed material Ⅱ (as powder). Add the mixed material Ⅱ into a mold, and then perform cold sintering at a pressure of 500 MPa and a sintering temperature of 45 °C for 60 min to obtain an H3BO3-h-BN composite ceramic material prepared by cold sintering. Place the H3BO3-h-BN composite ceramic material in a quartz boat, and then first introduce nitrogen into a tubular furnace for 20 min to remove the air in the tubular furnace, and then introduce ammonia for annealing treatment. Among them, the annealing temperature is 950 °C, the annealing time is 6 h, and the heating rate is 10 °C / min. As ammonia is introduced, the H3BO3 powder will react with ammonia to transform into BN. After the annealing is completed, cool it with the furnace to obtain a boron nitride ceramic material.

[0092] This example also provides a packaging substrate, including the boron nitride ceramic material prepared in this example.

[0093] This example also provides an electronic device, including the boron nitride ceramic material prepared in this example.

[0094] Example 4

[0095] This example discloses a boron nitride ceramic material, and its preparation process includes:

[0096] (Ⅰ) Take h-BN powder with an average particle size of 7 μm and H3BO3 powder with an average particle size of 1 μm (the volume ratio of h-BN powder to H3BO3 powder is 6:4). Mix the H3BO3 powder with water to obtain an H3BO3 aqueous solution (the dosage ratio of H3BO3 powder to water is 2.5 g powder: 200 mL water). Disperse the h-BN powder evenly in the H3BO3 aqueous solution, and then perform freeze-drying to obtain H3BO3-h-BN mixed material Ⅰ (in powder form). Using acetone as the solvent and zirconia balls as the ball-milling beads, ball-mill the H3BO3-h-BN mixed material Ⅰ to mix it evenly to obtain a mixed slurry; the ball-milling mixing time is 4 h, the ball-milling mixing speed is 600 rpm, and the ball-to-material ratio of ball-milling mixing is 2:1. Dry the mixed slurry in a forced-air drying oven at 50 °C, grind it, and sieve it through a 160-mesh sieve to obtain H3BO3-h-BN mixed powder.

[0097] (Ⅱ) Add deionized water (the mass of deionized water is 10% of the mass of H3BO3 powder) to the H3BO3-h-BN mixed powder, then use a mortar to grind it evenly, and let it stand at normal temperature and pressure for one day to obtain mixed material Ⅱ (in powder form). Put the mixed material Ⅱ into a mold, and then perform cold sintering at a pressure of 300 MPa and a sintering temperature of 25 °C for 30 min to obtain an H3BO3-h-BN composite ceramic material prepared by cold sintering. Place the H3BO3-h-BN composite ceramic material in a quartz boat, and then first introduce nitrogen gas into the tubular furnace for 20 min to remove the air in the tubular furnace, and then introduce ammonia gas for annealing treatment. Among them, the annealing temperature is 850 °C, the annealing time is 4 h, and the heating rate is 10 °C / min. As ammonia gas is introduced, the H3BO3 powder will react with ammonia gas to transform into BN. After the annealing is completed, it is cooled with the furnace to obtain a boron nitride ceramic material.

[0098] This embodiment also provides a packaging substrate, including the boron nitride ceramic material prepared in this embodiment.

[0099] This embodiment also provides an electronic device, including the boron nitride ceramic material prepared in this embodiment.

[0100] Example 5

[0101] This embodiment discloses a boron nitride ceramic material, and its preparation process includes:

[0102] (Ⅰ) Take h-BN powder with an average particle size of 15 μm and H3BO3 powder with an average particle size of 0.5 μm (the volume ratio of h-BN powder to H3BO3 powder is 5:5). Mix the H3BO3 powder with water to obtain an H3BO3 aqueous solution (the dosage ratio of H3BO3 powder to water is 2.5 g powder: 200 mL water). Disperse the h-BN powder evenly in the H3BO3 aqueous solution, and then perform freeze-drying to obtain the H3BO3-h-BN mixed material Ⅰ (in powder form). Using acetone as the solvent and zirconia balls as the ball-milling beads, ball-mill the H3BO3-h-BN mixed material Ⅰ to mix it evenly to obtain a mixed slurry; the ball-milling time is 4 h, the ball-milling speed is 600 rpm, and the ball-to-material ratio for ball-milling is 2:1. Dry the mixed slurry in a blast drying oven at 40 °C, grind it, and sieve it through an 80-mesh sieve to obtain the H3BO3-h-BN mixed powder.

[0103] (Ⅱ) Add deionized water (the mass of deionized water is 10% of the mass of the H3BO3 powder) to the H3BO3-h-BN mixed powder, then use a mortar to grind it evenly, and let it stand at room temperature and normal pressure for one day to obtain the mixed material Ⅱ (in powder form). Add the mixed material Ⅱ into a mold, and then perform cold sintering at a pressure of 300 MPa and a sintering temperature of 40 °C for 30 min to obtain the H3BO3-h-BN composite ceramic material prepared by cold sintering. Place the H3BO3-h-BN composite ceramic material in a quartz boat, and then first introduce nitrogen into the tubular furnace for 20 min to remove the air in the tubular furnace, and then introduce ammonia for annealing treatment. Among them, the annealing temperature is 950 °C, the annealing time is 4 h, and the heating rate is 10 °C / min. As ammonia is introduced, the H3BO3 powder will react with ammonia to transform into BN. After the annealing is completed, cool it with the furnace to obtain the boron nitride ceramic material.

[0104] This example also provides a packaging substrate, including the boron nitride ceramic material prepared in this example.

[0105] This example also provides an electronic device, including the boron nitride ceramic material prepared in this example.

[0106] Test example

[0107] This test example conducted performance tests on the boron nitride ceramic material obtained in the example, specifically including:

[0108] 1) For the boron nitride ceramic material prepared in Example 1 of the present invention, perform X-ray diffraction test, infrared spectroscopy test, and Raman spectroscopy test. The measured XRD pattern, infrared spectrum, and Raman spectrum are shown in Figures 1-3 respectively. It can be seen from Figures 1-3 that the boron nitride ceramic material was successfully prepared in the example of the present invention.

[0109] 2) The microstructure of the boron nitride ceramic material prepared in Example 1 of the present invention was tested (magnification 2000 times), and the test results are as Figure 4 shown.

[0110] 3) The density, thermal conductivity, dielectric constant, dielectric loss and boron nitride purity of the boron nitride ceramic materials prepared in Examples 1-5 of the present invention were tested. The density was measured by the Archimedes drainage method, the thermal conductivity was measured by the laser flash method, the dielectric constant and dielectric loss were measured by the resonant cavity method, and the boron nitride purity was measured by photoelectron spectroscopy. The test results are shown in Table 1. Among them, the purity of boron nitride is: the mass percentage of boron nitride in the boron nitride ceramic material;

[0111] Table 1

[0112]

[0113] The present invention discloses a boron nitride ceramic material with low-temperature sintering densification and its preparation method. The boron nitride ceramic with low-temperature sintering densification uses h-BN powder and H3BO3 powder as raw materials, and prepares a dense H3BO3-h-BN composite ceramic material through cold sintering, and then performs low-temperature annealing in an ammonia environment. Ammonia will react with H3BO3 to convert H3BO3 into BN, thereby preparing a dense boron nitride ceramic.

[0114] The present invention can prepare a dense boron nitride composite ceramic material by introducing a cold sintering process, and then a pure-phase boron nitride ceramic material can be obtained through annealing. Its cold sintering temperature is low (preferably 25-65 °C), and annealing can be carried out at a low temperature of 1000 °C, which is energy-saving and environmentally friendly, meets the requirements of the country's dual-carbon economy, and is conducive to achieving carbon peak and carbon neutrality; the boron nitride ceramic material prepared by the present invention is highly dense (the density can be 2.10 g·cm -3 or more), has a high thermal conductivity, a low dielectric constant and dielectric loss, and excellent performance. Its thermal conductivity can reach 50 W·m -1 ·K -1 or more, the dielectric constant can be reduced to less than 4.1, and the dielectric loss can be 2×10 -4 or less, meeting the requirements of high-frequency and high-speed circuit substrates and power electronics packaging applications; moreover, the raw materials of the present invention include commercial h-BN powder and H3BO3 powder, the raw material price is low, the process is simple, easy to control, the performance is stable, and it has broad application prospects.

[0115] The above has described the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for preparing a boron nitride ceramic material, characterized in that, The method comprises the following steps: taking a mixed powder composed of boron nitride and boric acid, subjecting it to cold sintering and annealing to obtain the boron nitride ceramic material; in the mixed powder, the volume ratio of boron nitride to boric acid is (5 - 110):5, the sintering temperature of the cold sintering is 10 - 80 °C, and the annealing is carried out in an atmosphere containing ammonia gas.

2. The preparation method of the boron nitride ceramic material according to claim 1, characterized in that, The sintering temperature of the cold sintering is 25 - 65 °C.

3. The preparation method of the boron nitride ceramic material according to claim 2, wherein, The sintering time of the cold sintering is 5 - 200 min.

4. The preparation method of the boron nitride ceramic material according to claim 3, characterized in that, The sintering time of the sintering is 10 - 120 min.

5. The preparation method of the boron nitride ceramic material according to claim 2, characterized in that, The pressure of the cold sintering is 100 - 600 MPa.

6. The preparation method of the boron nitride ceramic material according to claim 1, wherein, The annealing temperature is 700 - 1100 °C, and the annealing time is 0.5 - 8 h.

7. The preparation method of the boron nitride ceramic material according to any one of claims 1-6, characterized in that, The preparation method comprises the following steps: mixing the mixed powder with water to obtain mixture I, subjecting it to cold sintering, and annealing it in an atmosphere containing ammonia gas to obtain the boron nitride ceramic material.

8. The preparation method of the boron nitride ceramic material according to any one of claims 1-6, characterized in that, The preparation method includes preparing the mixed powder, and the preparation of the mixed powder includes the following operations: mixing boron nitride and an aqueous solution containing boric acid, and drying to obtain the mixed powder.

9. A boron nitride ceramic material, characterized in that, The boron nitride ceramic material is obtained by using the preparation method according to any one of claims 1 - 8.

10. The boron nitride ceramic material according to claim 9, characterized in that, The thermal conductivity of the boron nitride ceramic material is 35 W·m -1 ·K -1 or above.

11. The boron nitride ceramic material according to claim 10, wherein The dielectric loss of the boron nitride ceramic material is (1 - 5)×10 -4 .

12. An encapsulation substrate, characterized in that, The encapsulation substrate includes the boron nitride ceramic material according to any one of claims 9 - 11.

13. An electronic device, characterized in that, The electronic device includes the boron nitride ceramic material according to any one of claims 9 - 11.

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