Preparation method of silicon nitride ceramic substrate containing titanium nitride

Abstract

The invention provides a preparation method of a silicon nitride ceramic substrate containing titanium nitride. The preparation method comprises the following steps: step 1, preparing silicon nitride slurry doped with boron nitride nanotubes; step 2, carrying out tape casting on the silicon nitride slurry to obtain a boron nitride nanotube doped silicon nitride ceramic substrate green body; step 3, secondary tape casting is carried out on the silicon nitride ceramic substrate green body, so that the surface of the silicon nitride ceramic substrate green body is coated with a layer of titanium nitride film; step 4, preparing the boron nitride toughened silicon nitride composite ceramic substrate containing titanium nitride on the surface through glue discharging and sintering; and 5, pasting a silver foil on the surface of the boron nitride toughened silicon nitride composite ceramic substrate, pasting a copper sheet on the surface of the silver foil, and carrying out vacuum brazing to obtain the silicon nitride copper-clad plate. The problem that a traditional silicon nitride ceramic substrate is large in brittleness is solved, the toughness of the silicon nitride ceramic substrate is greatly improved, in the subsequent copper coating process, soldering paste can be directly removed, and the problem of product defects caused by the soldering paste is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of functional ceramics, and particularly relates to a preparation method of a silicon nitride ceramic substrate containing titanium nitride. BACKGROUND

[0002] With the development of the integrated circuit industry, power electronic device technology is developing towards high voltage, large current, high power density and small size. Therefore, an efficient heat dissipation system is an essential part of high integration. Therefore, the substrate material needs not only high thermal conductivity but also good mechanical reliability. At present, the most commonly used in the market are AlN and Al2O3 ceramic substrates, but the mechanical properties of the AlN ceramic substrate are poor, and the thermal conductivity of the Al2O3 ceramic substrate is low, which limits the use of the two as structural substrate materials. Therefore, it is urgent to find a high-thermal-conductivity substrate material with good mechanical properties.

[0003] Si3N4 ceramic has the characteristics of high strength, high hardness, high resistivity, good thermal shock resistance, low dielectric loss and low expansion coefficient, and is an ideal substrate material. However, the brittleness of silicon nitride ceramic seriously affects the wide use of silicon nitride ceramic. Therefore, how to change the toughness of silicon nitride ceramic is one of the focuses of current research. At the same time, the silicon nitride ceramic is mainly covered with copper through the AMB process, and the solder used in the printing process is prone to unevenness, and gas is easily released during the later soldering process, forming cavities and reducing the peel strength.

[0004] In the Chinese patent application with the patent number CN117820004A, a silicon nitride-based composite ceramic substrate and a preparation method thereof are disclosed. The silicon nitride-based composite ceramic substrate is composed of the following raw materials: 95-110 parts of silicon nitride, 4-8 parts of boron nitride whiskers, 7-14 parts of potassium hexatitanate whiskers, 22-38 parts of a sintering aid, 14-20 parts of a plasticizer, 6-15 parts of a dispersant, 16-25 parts of a binder, and 85-115 parts of an organic solvent. The application adds titanium carbonitride and zirconium tungstate to the silicon nitride-based substrate material, which not only improves the mechanical properties such as bending strength and fracture toughness of the silicon nitride-based ceramic substrate, but also further improves the bonding strength of the silicon nitride-based ceramic substrate to metals such as titanium, nickel and aluminum, and improves the overall reliability of the ceramic substrate. The application emphasizes the improvement of the bonding strength with metals. However, the present application emphasizes the fracture toughness and thermal conductivity of the substrate itself. The method used is the same as the conventional method, which adopts flow casting and sintering process. Only by adding other substances to improve the performance of the substrate. The application does not go through the degassing process, and carbon impurities and other residues may be left in the substrate, affecting the purity and performance of the substrate.

[0005] Based on the above, a silicon nitride composite ceramic substrate containing titanium nitride and boron nitride nanotubes is proposed, which can effectively solve the above problems. SUMMARY

[0006] The application aims to provide a preparation method of a silicon nitride ceramic substrate containing titanium nitride, which solves the problems of large brittleness and poor fracture toughness of the silicon nitride ceramic substrate during use, uneven distribution of brazing filler metal during copper cladding, and complicated process.

[0007] The application can be achieved by the following technical solutions: a preparation method of a silicon nitride ceramic substrate containing titanium nitride, which comprises the following steps:

[0008] Step 1: preparing a silicon nitride slurry containing boron nitride nanotube doping;

[0009] Step 2: casting the silicon nitride slurry to obtain a green body of a silicon nitride ceramic substrate containing boron nitride nanotube doping;

[0010] Step 3: performing secondary casting on the green body of the silicon nitride ceramic substrate to coat a thin film of titanium nitride on the surface of the green body of the silicon nitride ceramic substrate;

[0011] Step 4: preparing a boron nitride toughened silicon nitride composite ceramic substrate containing titanium nitride on the surface by degassing and sintering;

[0012] Step 5: pasting a silver foil on the surface of the boron nitride toughened silicon nitride composite ceramic substrate, pasting a copper sheet on the surface of the silver foil, and performing vacuum brazing to obtain a silicon nitride copper-clad plate.

[0013] The application can also be achieved by the following technical solutions:

[0014] Step 1 comprises:

[0015] Step 11: mixing the alpha-silicon nitride powder, boron nitride nanotubes, sintering aids, dispersants and solvents in a certain proportion to perform first ball milling;

[0016] Step 12: after the first ball milling, adding plasticizers and binders to perform second ball milling to obtain a silicon nitride slurry containing boron nitride nanotube doping.

[0017] In step 11, the mass ratio of the alpha-silicon nitride powder, the boron nitride nanotubes and the sintering aids is (80-95):(0.1-5):(1-15); the alpha-silicon nitride powder is high-purity submicron particles, the content of alpha-phase silicon nitride is not less than 95%, the oxygen content is less than 2%, and the particle size D50 is less than or equal to 0.8 um.

[0018] In step 11, the boron nitride nanotube has a length of 10-100 um, an average diameter of < 150 nm, and a purity of ≥ 99%; the sintering aid is yttrium oxide and magnesium oxide, with a mass ratio of (1-3):(1-5); the dispersant is one of triethyl phosphate, triolein, menhaden oil, and acrylate, with a mass of 0.1%-5% of the total mass of the α-silicon nitride powder, the boron nitride nanotube, and the sintering aid; and the first ball milling is performed using a planetary ball mill at a speed of 100-400 r / min for 1-20 h.

[0019] In step 12, the second ball milling is performed at a speed of 200-350 r / min for 24 h; the plasticizer is one of polyethylene glycol, dibutyl phthalate, dioctyl phthalate, and glycerol; the binder is one of poly(methyl acrylate), polyvinyl butyral, and polymethyl methacrylate; and the mass ratio of the plasticizer to the binder is 0.6-1.2.

[0020] The method for preparing the silicon nitride ceramic substrate containing titanium nitride further comprises, after step 1, placing the ball-milled silicon nitride slurry doped with boron nitride nanotubes in a vacuum defoaming machine for defoaming treatment.

[0021] In step 3, the titanium nitride powder, the dispersant, and the binder are dispersed in anhydrous ethanol solvent, stirred uniformly, and coated on the surface of the silicon nitride ceramic substrate green body in a layer of titanium nitride by a flow casting process; the thickness of the titanium nitride coating is 1-100 um after drying; the dispersant is polyethylene glycol; and the binder is one of poly(methyl acrylate), polyvinyl butyral, and polymethyl methacrylate.

[0022] In step 4, the silicon nitride ceramic substrate coated with titanium nitride is placed in a degassing furnace for degassing treatment; the degassing temperature is 200-600 ℃ under an inert atmosphere, and the degassing time is 1-30 h; and after the degassing is completed, the silicon nitride ceramic substrate is placed in a sintering furnace for high-temperature sintering treatment.

[0023] In step 4, the high-temperature sintering process is divided into the following stages:

[0024] (61) from room temperature to 1200-1500 ℃ at a rate of 10 ℃ / min;

[0025] (62) when heated to 1200-1500 ℃, constant temperature for 2-13 h, pressure 0.1-1 MPa;

[0026] (63) after constant temperature, continue to increase the temperature to 1700-1950 ℃ at a rate of 2 ℃ / min;

[0027] (64) after heating to 1700-1950 ℃, constant temperature for 2-24 h, pressure 1-10 MPa;

[0028] (65) After the isothermal process, the temperature is decreased to 1100℃ at a rate of 1-5℃ / min.

[0029] (66) Natural cooling from 1100℃ to room temperature.

[0030] In step 5, the silver foil thickness is 5-40um.

[0031] The method for preparing the titanium nitride-containing silicon nitride ceramic substrate in the application comprises the following steps: mixing silicon nitride powder, boron nitride nanotubes, sintering aids, dispersants, solvents and the like according to a certain proportion, ball milling, adding plasticizers and binders for secondary ball milling to obtain a required slurry, and obtaining a boron nitride nanotube-doped silicon nitride ceramic substrate green body through a flow casting method. Meanwhile, the titanium nitride is uniformly mixed with dispersants and binders in a solvent, and a layer of titanium nitride film is coated on the surface of the green body through secondary flow casting. Finally, a boron nitride toughened silicon nitride composite ceramic substrate containing titanium nitride on the surface is prepared through processes such as degassing and sintering, and then a silver foil is attached to the surface of the substrate, and a copper sheet is attached to the surface of the silver foil, and vacuum brazing is performed in a vacuum furnace, so that a silicon nitride copper-clad plate is finally obtained. The application solves the problem of large brittleness of the traditional silicon nitride ceramic substrate, greatly improves the toughness, and directly removes the solder paste in the subsequent copper cladding process due to the titanium nitride layer on the surface, thereby solving the problem of product defects caused by the solder paste. Compared with the prior art, the application has the following technical advantages:

[0032] (1) The current AMB copper cladding process mainly adds solder paste between the copper and the ceramic substrate, which is prone to uneven distribution of the solder paste, outgassing of the solder paste during brazing, and other adverse phenomena such as the formation of cavities in the interface, thereby affecting the bonding strength between the copper and the ceramic substrate. In the application, a layer of titanium nitride is directly coated on the surface of the ceramic green body, and the organic matter used can be removed during the degassing and sintering of the substrate, thereby reducing the generation of gas during the subsequent brazing process, and increasing the bonding strength between the copper and the ceramic substrate.

[0033] (2) Simplify the process steps, reduce the operation difficulty, and improve the product yield. In the brazing process, solder paste printing is not required, and the silver foil can be directly attached to the surface of the ceramic substrate, and then the copper sheet is attached to the surface of the silver foil for vacuum brazing.

[0034] (3) The titanium nitride can better diffuse into the pores of the silicon nitride together with the silicon nitride during sintering, thereby improving the uniformity of the titanium nitride distribution and enhancing the bonding force with the ceramic.

[0035] (4) effectively improve the problem of large brittleness of silicon nitride ceramic substrate, boron nitride nanotubes in silicon nitride ceramic substrate mainly play a toughening effect, when the crack propagation encounters the block of boron nitride nanotubes, deflection and pullout may occur. These phenomena will consume most of the energy of crack propagation, thereby improving the toughness of silicon nitride ceramic substrate.

[0036] (5) boron nitride nanotubes have strong oxidation resistance, and the boron nitride nanotubes toughened silicon nitride ceramic substrate has high reliability, which is more conducive to industrialized mass production. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The flow chart of a specific embodiment of the silicon nitride ceramic substrate containing titanium nitride prepared by the method of the present application. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0039] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation and / or combination thereof.

[0040] As shown in Figure 1 , Figure 1 The flow chart of the silicon nitride ceramic substrate containing titanium nitride prepared by the method of the present application. The silicon nitride ceramic substrate containing titanium nitride prepared by the method comprises:

[0041] Step 1, first ball milling, a certain amount of α-silicon nitride powder, boron nitride nanotubes, sintering aid, dispersant and solvent are ball milled and mixed.

[0042] The mass ratio of the α-silicon nitride powder, boron nitride nanotubes and sintering aid is (80-95):(0.1-5):(1-15).

[0043] The a-silicon nitride powder is high-purity submicron particles, the content of α-phase silicon nitride is not less than 95%, the oxygen content is less than 2%, and the particle size D50 is ≤0.8um.

[0044] The length of the boron nitride nanotubes is 10-100um, the average diameter is <150nm, and the purity is ≥99%.

[0045] The sintering aids are yttrium oxide and magnesium oxide, and the mass ratio is (1-3):(1-5).

[0046] The dispersant is one of triethyl phosphate, triolein, herring oil, acrylate, etc. The mass is 0.1%-5% of the total mass of silicon nitride powder, boron nitride nanotube and sintering aid.

[0047] The planetary ball mill is used for the ball milling, the rotation speed is 100-400r / min, preferably 150-300r / min, and the time is 1-20h.

[0048] After the first ball milling, the second ball milling is carried out by adding appropriate amount of plasticizer and binder, the rotation speed is 200-350r / min, and the time is 24h.

[0049] The plasticizer is one of polyethylene glycol, dibutyl phthalate, dioctyl phthalate, glycerol, etc., and the binder is one of poly(methyl acrylate), polyvinyl butyral, polymethyl methacrylate, etc. The mass ratio of plasticizer and binder is 0.6-1.2, preferably 0.8-1.1.

[0050] In step 3, the slurry after ball milling is placed in a vacuum defoaming machine for defoaming treatment.

[0051] In step 4, the slurry is drawn into a silicon nitride green body by using a casting machine.

[0052] In step 5, the titanium nitride powder, dispersant and binder are dispersed into the solvent, stirred uniformly, and a layer of titanium nitride is coated on the surface of the silicon nitride green body by using the casting process.

[0053] The thickness of the titanium nitride coating after drying is 1-100um.

[0054] The dispersant is polyethylene glycol, and the binder is one of the above types.

[0055] In step 6, the green body coated with titanium nitride is placed in a glue removal furnace for glue removal treatment. The glue removal temperature is 200-600℃, the inert atmosphere is used, the glue removal time is 1-30h, and then the high temperature sintering treatment is carried out in a sintering furnace.

[0056] The sintering process is divided into the following stages:

[0057] (61) from room temperature to 1200-1500℃, the heating rate is 10℃ / min;

[0058] (62) when heated to 1200-1500℃, the temperature is kept constant for 2-13h, and the pressure is 0.1-1MPa;

[0059] (63) After the constant temperature is ended, the temperature is continuously increased to 1700-1950℃, and the increasing rate is 2℃ / min;

[0060] (64) After the temperature is increased to 1700-1950℃, the temperature is kept constant for 2-24h, and the pressure is 1-10MPa;

[0061] (65) After the constant temperature is ended, the temperature is decreased to 1100℃ at the rate of 1-5℃ / min;

[0062] (66) The natural temperature decreasing is performed from 1100℃ to room temperature.

[0063] Step 7, the silver foil is pasted on the side of the substrate containing the titanium nitride, and then the copper sheet is pasted, and the silicon nitride copper-clad plate is obtained by vacuum brazing.

[0064] The thickness of the silver foil is 5-40um.

[0065] The following are several specific embodiments of the application

[0066] Example 1

[0067] 94.8g of α-silicon nitride powder, 0.2g of boron nitride nanotube, 2g of yttrium oxide, 3g of magnesium oxide and 1% of the dispersant triethyl phosphate, and an appropriate amount of solvent are put into a ball mill, and the first ball milling is performed, the ball milling time is 8h, and the rotating speed is 180r / min. After the end, 6.4g of the plasticizer polyethylene glycol and 8g of the adhesive polyvinyl butyral are added, and the second ball milling is performed, the ball milling rotating speed is 300r / min, and the time is 24h. The ball-milled slurry is placed in a vacuum defoaming machine for defoaming treatment. The silicon nitride ceramic substrate green body is obtained by the flow casting. Then the titanium nitride powder, polyethylene glycol and polyvinyl butyral are uniformly dispersed in anhydrous ethanol by stirring, and a 5um-thick titanium nitride film is coated on the surface of the silicon nitride green body by flow casting. The green body is placed in a degassing furnace for degassing treatment, the degassing temperature is 200-600℃, and the time is 1-30h. After the degassing is ended, the semi-finished product is taken out and placed in a sintering furnace for high-temperature sintering, the temperature is increased from room temperature to 1200-1500℃ at the rate of 10℃ / min, and kept constant at this temperature for 6h, the pressure is 0.1-1MPa, the temperature is continuously increased to 1800-1950℃ at the rate of 2℃ / min, and kept constant for 16h, the pressure is 1-10MPa; the temperature is decreased to 1100℃ at the rate of 3℃ / min, and then the natural temperature decreasing is performed to room temperature. The silver foil is pasted on the side of the substrate containing the titanium nitride, and then the copper sheet of 0.3mm is pasted, and the silicon nitride copper-clad plate is obtained by vacuum brazing.

[0068] Example 2

[0069] Put 90 g of α-silicon nitride powder, 1 g of boron nitride nanotube, 3.6 g of yttrium oxide, 5.4 g of magnesium oxide, and 2.1% of a dispersant glycerol trioleate, and an appropriate amount of solvent into a ball mill, and perform first ball milling for 11 h at a rotation speed of 180 r / min. After completion, 5 g of a plasticizer dioctyl phthalate and 5 g of a binder polyacrylate are added, and second ball milling is performed at a rotation speed of 300 r / min for 24 h. The slurry after ball milling is subjected to defoaming treatment in a vacuum defoaming machine. A silicon nitride ceramic substrate green body is obtained by a flow casting method. Then, titanium nitride powder, polyethylene glycol, and polyvinyl butyral are uniformly dispersed in anhydrous ethanol by stirring, and a 10-μm-thick titanium nitride film is coated on the surface of the silicon nitride green body by a flow casting process. The green body is placed in a degassing furnace for degassing treatment, and the degassing temperature is 200-600°C, and the time is 1-30 h. After the degassing is completed, the semi-finished product is taken out and placed in a sintering furnace for high-temperature sintering. The temperature is increased from room temperature to 1200-1500°C at a rate of 10°C / min, and then held at this temperature for 6 h under a pressure of 0.1-1 MPa. The temperature is further increased to 1800-1950°C at a rate of 2°C / min, and then held at this temperature for 16 h under a pressure of 1-10 MPa. After the temperature holding is completed, the temperature is decreased to 1100°C at a rate of 3°C / min, and then naturally cooled to room temperature. Silver foil is attached to the side of the substrate containing titanium nitride, and then a 0.3-mm-thick copper sheet is attached, and a silicon nitride copper-clad plate is obtained by vacuum brazing.

[0070] Example 3

[0071] Put 86 g of α-silicon nitride powder, 3 g of boron nitride nanotube, 2.2 g of yttrium oxide, 8.8 g of magnesium oxide, and 2.5% of a dispersant acrylate, and an appropriate amount of solvent into a ball mill, and perform first ball milling for 11 h at a rotation speed of 200 r / min. After completion, 7.2 g of a plasticizer glycerol and 8 g of a binder polyvinyl butyral are added, and second ball milling is performed at a rotation speed of 300 r / min for 24 h. The slurry after ball milling is subjected to defoaming treatment in a vacuum defoaming machine. A silicon nitride ceramic substrate green body is obtained by a flow casting method. Then, titanium nitride powder, polyethylene glycol, and polyvinyl butyral are uniformly dispersed in anhydrous ethanol by stirring, and a 20-μm-thick titanium nitride film is coated on the surface of the silicon nitride green body by a flow casting process. The green body is placed in a degassing furnace for degassing treatment, and the degassing temperature is 200-600°C, and the time is 5-30 h. After the degassing is completed, the semi-finished product is taken out and placed in a sintering furnace for high-temperature sintering. The sintering and brazing processes are the same as in Example 1, and a silicon nitride copper-clad plate is finally obtained.

[0072] Example 4

[0073] Put 81 g of α-silicon nitride powder, 4.6 g of boron nitride nanotube, 5.4 g of yttrium oxide, 9 g of magnesium oxide and 3.5% of dispersant herring oil, and an appropriate amount of solvent into a ball mill, and perform first ball milling for 11 h at a speed of 200 r / min. After the end, 8 g of plasticizer polyethylene glycol and 8.8 g of adhesive polymethyl methacrylate are added for second ball milling at a speed of 300 r / min for 24 h. The milled slurry is placed in a vacuum defoaming machine for defoaming treatment. A silicon nitride ceramic substrate green body is obtained by a flow casting method. Then the titanium nitride powder, polyethylene glycol and polyvinyl butyral are uniformly dispersed in anhydrous ethanol by stirring, and a 70 um thick titanium nitride film is coated on the surface of the silicon nitride green body by flow casting process. The green body is placed in a degassing furnace for degassing treatment, and the degassing temperature is 200-600℃ and the time is 5-30 h. After degassing, the semi-finished product is taken out and placed in a sintering furnace for high temperature sintering. The sintering and brazing process is the same as that of example 1, and finally a silicon nitride copper clad plate is obtained.

[0074] In order to better illustrate the advantages of the present application, the fracture toughness of the silicon nitride ceramic substrate prepared in the above examples and the peeling strength after copper cladding are tested, and the test results are shown in the following table:

[0075] Table 1 Fracture toughness of silicon nitride ceramic substrate and peeling strength after copper cladding

[0076]

[0077] As can be seen from the above table, with the increase of the amount of boron nitride nanotube doping, the fracture toughness increases first and then decreases. The peeling strength increases first and then decreases with the increase of the amount of titanium nitride.

[0078] Finally, it should be pointed out that: the above only describes the preferred embodiments of the present application, and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing examples, for those skilled in the art, the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0079] In addition to the technical features described in the specification, they are known to those skilled in the art.

Claims

1. A method for preparing a silicon nitride ceramic substrate containing titanium nitride, characterized in that: The method for preparing a silicon nitride ceramic substrate containing titanium nitride comprises: Step 1, preparing silicon nitride slurry doped with boron nitride nanotubes; Step 2: tape-casting the silicon nitride slurry to obtain a green body of a silicon nitride ceramic substrate doped with boron nitride nanotubes; Step 3, performing secondary tape casting on the silicon nitride ceramic substrate green body to coat a titanium nitride thin film on the surface of the silicon nitride ceramic substrate green body; Step 4, preparing a boron nitride toughened silicon nitride composite ceramic substrate with titanium nitride on the surface by debinding and sintering; Step 5: affix a silver foil to the surface of the boron nitride toughened silicon nitride composite ceramic substrate, and then affix a copper sheet to the surface of the silver foil, and perform vacuum brazing to obtain a silicon nitride copper clad laminate.

2. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 1, wherein: Step 1 includes: Step 11, mixing α-silicon nitride powder, boron nitride nanotubes, a sintering aid, a dispersant, and a solvent in a certain proportion, and performing a first ball milling; Step 12: After the first ball milling is completed, a plasticizer and a binder are added to perform a second ball milling to obtain a silicon nitride slurry doped with boron nitride nanotubes.

3. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 2, wherein: In step 11, the mass ratio of the α-silicon nitride powder, the boron nitride nanotubes, and the sintering aid is (80-95): (0.1-5): (1-15); the α-silicon nitride powder is high-purity submicron particles, the α-phase silicon nitride content is not less than 95%, the oxygen content is less than 2%, and the particle size D50 is ≤ 0.8 μm.

4. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 2, wherein: In step 11, the boron nitride nanotubes have a length of 10-100 μm, an average diameter of <150 nm, and a purity of ≥99%; the sintering aids are yttrium oxide and magnesium oxide, with a mass ratio of (1-3):(1-5); the dispersant is one of triethyl phosphate, triolein, herring oil, and acrylate, with a mass of 0.1%-5% of the total mass of the α-silicon nitride powder, the boron nitride nanotubes, and the sintering aid; the first ball milling uses a planetary ball mill with a rotation speed of 100-400 r / min and a time of 1-20 h.

5. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 2, wherein: In step 12, the second ball milling speed is 200-350 r / min, and the time is 24 hours; the plasticizer is one of polyethylene glycol, dibutyl phthalate, dioctyl phthalate, and glycerol, and the binder is one of polymethyl acrylate, polyvinyl butyral, and polymethacrylic acid; the mass ratio of the plasticizer to the binder is 0.6-1.

2.

6. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 2, wherein: The method for preparing a silicon nitride ceramic substrate containing titanium nitride further comprises, after step 1, placing the ball-milled silicon nitride slurry doped with boron nitride nanotubes in a vacuum degassing machine for degassing.

7. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 1, wherein: In step 3, titanium nitride powder, a dispersant, and a binder are dispersed in anhydrous ethanol, stirred evenly, and a layer of titanium nitride is coated on the surface of the silicon nitride ceramic substrate green body by a tape casting process; the titanium nitride coating has a thickness of 1-100 μm after drying; the dispersant is polyethylene glycol; and the binder is one of polymethyl acrylate, polyvinyl butyral, and polymethacrylic acid.

8. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 1, wherein: In step 4, the silicon nitride ceramic substrate green body coated with titanium nitride is placed in a debinding furnace for debinding treatment; the debinding temperature is 200-600° C., under an inert atmosphere, and the debinding time is 1-30 hours; after debinding, it is placed in a sintering furnace for high-temperature sintering treatment.

9. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 8, wherein: In step 4, the high temperature sintering process is divided into the following stages: (61) From room temperature to 1200-1500 °C, heating rate 10 °C / min; (62) When heated to 1200-1500°C, maintain constant temperature for 2-13 hours and pressure of 0.1-1 MPa; (63) After the constant temperature is completed, the temperature is continued to rise to 1700-1950 °C at a heating rate of 2 °C / min; (64) After heating to 1700-1950°C, maintain the temperature for 2-24 hours at a pressure of 1-10 MPa; (65) After the constant temperature is completed, the temperature is lowered to 1100°C at a rate of 1-5°C / min; (66) The temperature was naturally cooled from 1100°C to room temperature.

10. The method for preparing a silicon nitride ceramic substrate containing titanium nitride according to claim 1, wherein: In step 5, the thickness of the silver foil is 5-40 μm.

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