Electrode slurry and method of preparing the same

Abstract

This invention discloses an electrode paste comprising carbon nanotube-microcapsule tungsten powder. The carbon nanotube-microcapsule tungsten powder consists of carbon nanotubes and microcapsule tungsten powder, with tungsten powder at the center of the microcapsule. The wall material is a mixture of a first resin and a second resin; the first resin includes an acrylic resin, and the second resin includes cellulose ether; the mass ratio of carbon nanotubes to microcapsule tungsten powder in the carbon nanotube-microcapsule tungsten powder is (0.1~1.25):(98.75~99.9). This composite powder, combined with inorganic glass powder, an organic carrier, and an organic solvent, ultimately yields an electrode paste with improved film thickness variation, oxidation rate, and sheet resistance. It is suitable for screen printing and high-temperature co-firing processes, significantly enhancing the adsorption performance of electrostatic chucks, and is applicable to the field of semiconductor precision machining.

Description

Technical Field

[0001] This invention relates to high-temperature co-fired ceramic electrode pastes, specifically to a tungsten-based electrode paste synergistically modified by microcapsule encapsulation and carbon nanotube doping. Background Technology

[0002] Electrostatic chucks are core clamping components used to hold wafers in precision semiconductor manufacturing processes (such as physical vapor deposition, etching, and ion implantation). The strength of their electrostatic adsorption capacity directly determines the positional stability and temperature uniformity of the wafer during the process, thus affecting product yield and equipment reliability. As semiconductor feature sizes continue to shrink and process complexity increases, more stringent requirements are being placed on the adsorption uniformity, high-temperature stability, and conductivity of electrostatic chucks.

[0003] The electrode layer, as the core component for electrostatic adsorption in an electrostatic chuck, directly affects the overall performance of the chuck due to its conductivity, film uniformity, and high-temperature oxidation resistance. Currently, electrostatic chuck electrode layers are mostly prepared using traditional tungsten paste through screen printing and high-temperature co-firing ceramic processes. However, traditional tungsten pastes suffer from three major problems in practical applications:

[0004] (1) Discontinuous conductive network: Tungsten powder particles are mainly in point contact, making it difficult to form a continuous conductive path, resulting in generally high sheet resistance of the electrode layer (usually 30-50 mΩ / □), insufficient charge accumulation capacity, and weak adsorption force.

[0005] (2) High temperature oxidation: Tungsten powder is easy to react with residual oxygen during high temperature sintering to form tungsten oxide (WO3). The conductivity of the oxidation product is much lower than that of metallic tungsten, which seriously damages the conductive path and reduces the service life of the electrode.

[0006] (3) Poor uniformity of film layer: Traditional tungsten paste has poor rheological properties, and the thickness of the film layer after screen printing varies by 4 to 6 μm, resulting in uneven electric field distribution of the electrode layer, local fluctuation of adsorption force, and affecting the stability of wafer processing.

[0007] To overcome these shortcomings, existing technologies mainly employ single modification strategies. For example, increasing the tungsten powder content to increase the proportion of the conductive phase leads to a sharp increase in slurry viscosity and a significant deterioration in screen printing performance. Alternatively, metal oxides (such as ruthenium oxide and indium tin oxide) can be added as auxiliary conductive phases, but due to the high interfacial resistance between the oxides and tungsten powder, it is difficult to form a continuous, low-resistance conductive network, resulting in limited improvement in conductivity. Furthermore, some studies have attempted to use microencapsulation technology to surface-treat tungsten powder in order to isolate oxygen and improve powder dispersibility, but single encapsulation treatment fails to solve the problem of conductive network construction because it does not incorporate carbon nanotubes. Other studies have attempted to add carbon nanotubes to the slurry to construct one-dimensional conductive channels, but this has not been effectively combined with the microencapsulation process of tungsten powder, resulting in poor conductive network construction. Summary of the Invention

[0008] To address the technical shortcomings of existing traditional tungsten pastes, such as poor conductivity, insufficient film uniformity, and susceptibility to oxidation at high temperatures, this invention provides an electrode paste and its preparation method. Through the synergistic modification of "microencapsulated tungsten powder + carbon nanotube conductive network", the adsorption electrode layer achieves "low sheet resistance, high film uniformity, and strong high-temperature stability", meeting the requirements of electrostatic chucks in semiconductor processing.

[0009] To achieve the above objectives, the first aspect of the present invention provides an electrode slurry comprising carbon nanotube-microcapsule tungsten powder;

[0010] The carbon nanotube-microcapsule tungsten powder includes carbon nanotubes and microcapsule tungsten powder;

[0011] The center of the microcapsule tungsten powder is tungsten powder, and the wall material is a mixture including a first resin and a second resin;

[0012] The first resin includes an acrylic resin, and the second resin includes a cellulose ether;

[0013] The mass ratio of carbon nanotubes to microcapsule tungsten powder in the carbon nanotube-microcapsule tungsten powder is (0.1 ~ 1.25):(98.75 ~ 99.9);

[0014] Furthermore, in the wall material, the mass ratio of the mixture of the first resin and the second resin is 1:3~10;

[0015] Furthermore, the carbon nanotubes are selected from single-walled carbon nanotubes and multi-walled carbon nanotubes, wherein the average diameter of the single-walled carbon nanotubes is 1 to 3 nm and the average diameter of the multi-walled carbon nanotubes is 10 to 50 nm.

[0016] Furthermore, the carbon nanotubes are a combination of single-walled carbon nanotubes and multi-walled carbon nanotubes;

[0017] Furthermore, the electrode paste comprises 80 to 90 parts by weight of carbon nanotube-microcapsule tungsten powder, 3 to 10 parts by weight of binder phase powder, 5 to 10 parts by weight of organic carrier, 0.5 to 1 part by weight of additives and 3 to 10 parts by weight of organic solvent.

[0018] Furthermore, the binder phase powder comprises 98.0~99.5 wt% alumina and 0.4~1.6 wt% calcium oxide;

[0019] Furthermore, the organic carrier comprises a resin and a solvent in a mass ratio of 1:3 to 8, wherein the resin comprises a mixture of acrylic resin and ethyl cellulose in a mass ratio of 1 to 5:1, and the solvent is selected from at least one of terpineol, dodecyl alcohol ester, and dioctyl phthalate systems.

[0020] The second aspect of the present invention provides a method for preparing the electrode paste described in the first aspect of the present invention, comprising the integrated preparation of carbon nanotube-microcapsule tungsten powder: after the tungsten powder is oscillated and coated by the wall material liquid, it is mixed with the carbon nanotube dispersion to obtain carbon nanotube-microcapsule tungsten powder.

[0021] Furthermore, the mass ratio of the tungsten powder to the wall material liquid is 1:2~5, and the mass ratio of acetone to hydrogenated terpineol in the wall material liquid is 3~8:1;

[0022] In the carbon nanotube dispersion, the organic solvents are polyvinylpyrrolidone and N-methylpyrrolidone, with a mass ratio of polyvinylpyrrolidone to carbon nanotubes of 2~5:1 and a mass ratio of N-methylpyrrolidone to carbon nanotubes of 50~100:1.

[0023] Beneficial effects:

[0024] (1) The flexible wall material of microcapsule tungsten powder can fill the fine pores of the electrode layer, reducing the difference in film thickness. The wall material can also isolate tungsten powder from air and can withstand sintering at 1600℃, reducing the oxidation rate of the adsorption electrode layer.

[0025] (2) The slight reducing properties of carbon nanotubes (which can react with trace amounts of oxygen at high temperatures) can help reduce the oxidation rate of tungsten powder. At high temperatures, a small amount of amorphous carbon will be generated on the surface of carbon nanotubes, which will undergo slight interfacial reactions with the binder phase and the substrate (such as forming SiC and Al4C3), thereby enhancing the interfacial bonding force and improving the co-firing compatibility.

[0026] (3) The synergistic effect of microcapsule-coated tungsten powder and carbon nanotubes, the carbon nanotubes construct a continuous conductive network, and form a "metal-carbon" composite pathway with the microcapsule tungsten powder, which reduces the overall sheet resistance of the adsorption electrode layer and improves the screen printing performance and adhesion.

[0027] (4) Further control of the wall material composition ratio can adjust the adhesion, sheet resistance and screen printing performance; further control of the average diameter of carbon nanotubes can adjust the sheet resistance and screen printing performance; further use of the combination of single-walled carbon nanotubes and multi-walled carbon nanotubes can adjust the film thickness difference, co-firing matching and screen printing performance. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] <Electrode Paste>

[0030] The electrode paste includes carbon nanotube-microcapsule tungsten powder, binder powder, organic carrier, additives and organic solvents. It is used to prepare high-temperature co-fired ceramic-based electrostatic chuck electrode layers. It is suitable for 200-400 mesh screen printing, co-firing temperature >1600℃, and adhesion to the ceramic substrate ≥15MPa.

[0031] Carbon nanotubes-microcapsule tungsten powder

[0032] The carbon nanotube-microcapsule tungsten powder is prepared as a single unit, comprising microcapsule tungsten powder and carbon nanotubes. Specifically, a wall material consisting of a first resin and a second resin is first formed outside the tungsten powder, and then carbon nanotubes are added to dope the wall material consisting of the first resin and the second resin, thereby obtaining the carbon nanotube-microcapsule tungsten powder prepared as a single unit.

[0033] The core of the microcapsule tungsten powder is tungsten powder, and the wall material is a mixture of a first resin and a second resin. The first resin includes an acrylic resin, preferably one or more of a homopolymer or copolymer of acrylic acid, methacrylic acid and their ester monomers. The second resin includes a cellulose ether, preferably one or more of methylcellulose, ethylcellulose, hydroxypropylcellulose and hydroxyethylcellulose.

[0034] The flexible wall material of microencapsulated tungsten powder can fill the fine pores of the electrode layer, reducing the thickness difference of the film. This wall material also isolates the tungsten powder from air, allowing it to withstand sintering at 1600℃ and reducing the oxidation rate of the adsorbed electrode layer. The first resin forms a dense and flexible film, firmly coating the tungsten powder and providing mechanical strength; the second resin has excellent solubility and can adjust the hydrophobicity of the wall material and the rheological properties of the slurry. The combination of these two materials results in a wall material with good shell integrity and crack resistance, while also improving the dispersion stability of the powder in the organic carrier and its screen printing performance.

[0035] The synergistic effect of microencapsulated tungsten powder and carbon nanotubes allows the carbon nanotubes to construct a continuous conductive network, forming a "metal-carbon" composite pathway with the microencapsulated tungsten powder, thereby reducing the overall sheet resistance of the adsorption electrode layer.

[0036] In the wall material, the mass ratio of the mixture of the first resin and the second resin is 1:3~10. Controlling this mass ratio within the above range can further reduce the film thickness variation and decrease the oxidation rate.

[0037] The preparation of microcapsule-coated tungsten powder involves adding tungsten powder to a wall material solution and agitating to coat it. The wall material solution comprises a mixture of a first resin and a second resin at a mass ratio of 1:3-10, and a mixture of acetone and hydrogenated terpineol. Using the acetone-hydrogenated terpineol mixture, acetone rapidly dissolves the wall material and promotes shell formation, while hydrogenated terpineol delays evaporation and improves wetting and dispersion. Together, they form smooth and intact microcapsules. Acetone alone evaporates too quickly, making the shell prone to rupture; hydrogenated terpineol alone evaporates too slowly, making shell formation difficult.

[0038] The carbon nanotubes are selected from single-walled carbon nanotubes and multi-walled carbon nanotubes. To further reduce sheet resistance, the average diameter of single-walled carbon nanotubes can be controlled at 1 to 3 nm, and the average diameter of multi-walled carbon nanotubes can be controlled at 10 to 50 nm. The mass ratio of carbon nanotubes to microcapsule tungsten powder in the carbon nanotube-microcapsule tungsten powder is controlled at (0.1 ~ 1.25): (98.75 ~ 99.9).

[0039] By controlling the diameter of single-walled carbon nanotubes to 1~3 nm and the diameter of multi-walled carbon nanotubes to 10~50 nm, the fine single-walled carbon nanotubes have high flexibility and large specific surface area, which can fill the gaps between tungsten powder particles, increase the conductive contact points, and significantly reduce sheet resistance; the coarse multi-walled carbon nanotubes have high rigidity, forming a stable three-dimensional skeleton in the slurry, improving the rheology and anti-collapse properties during screen printing, and at the same time improving the structural strength of the film after sintering.

[0040] Furthermore, by using both single-walled carbon nanotubes and multi-walled carbon nanotubes, the high rigidity of the multi-walled carbon nanotubes prevents collapse defects caused by excessive softness or curling during the printing process, maintaining dimensional stability. The single-walled carbon nanotubes assist in leveling, improve screen printing performance and co-firing compatibility, and reduce film thickness differences.

[0041] By controlling the mass ratio of carbon nanotubes to microcapsule tungsten powder to (0.1~1.25):(98.75~99.9), the synergistic effect of carbon nanotubes and microcapsule tungsten powder can be fully utilized. The dense carbon network formed by the two is tightly bonded to the tungsten powder, which not only enhances adhesion but also avoids agglomeration or insulation isolation caused by excessive carbon nanotubes. This ratio ensures that the carbon nanotubes are uniformly dispersed in the gaps between the tungsten powder without compromising the powder's packing density, thereby achieving a synergistic improvement in low sheet resistance, superior printability, and high adhesion.

[0042] Binder Powder

[0043] The binder phase powder comprises 98.0–99.5 wt% alumina and 0.4–1.6 wt% calcium oxide. In addition to alumina and calcium oxide, it also includes yttrium oxide, silica, kaolin, and talc in a mass ratio of 0.025–0.1 : 0.035–0.14 : 0.025–0.1 : 0.015–0.06.

[0044] The binder phase powder is mainly composed of alumina, supplemented with calcium oxide, yttrium oxide, silica, kaolin, talc, and other additives. Its main functions are to connect the conductive phase to the ceramic matrix, adjust the coefficient of thermal expansion, and promote dense sintering. By controlling the binder phase powder within the above-mentioned proportions, low sheet resistance, strong bonding, and defect-free co-firing can be synergistically achieved.

[0045] organic carrier

[0046] The organic carrier comprises a resin and a solvent in a mass ratio of 1:3 to 8, wherein the resin comprises a mixture of acrylic resin and ethyl cellulose in a mass ratio of 1 to 5:1, and the solvent is selected from at least one of the following systems: terpineol, dodecyl alcohol ester, and dioctyl phthalate.

[0047] In organic carrier resins, acrylic resin provides film-forming properties and wetting dispersion, while ethyl cellulose adjusts the thixotropy of the slurry and promotes low-temperature degreasing. Controlling the mass ratio of acrylic resin and ethyl cellulose mixture in the range of 1 to 5:1 and the mass ratio of resin to solvent in the range of 1:3 to 8 helps to improve screen printing performance.

[0048] Additives

[0049] The additives include thixotropic agents, leveling agents, defoamers, and dispersants; the thixotropic agent is selected from at least one of polyamide wax and hydrogenated castor oil, the leveling agent is selected from at least one of polydimethylsiloxane and polyacrylate, the defoamer is selected from at least one of organosiloxane and mineral oil, and the dispersant is selected from at least one of sorbitan monooleate, polyethylene glycol 400, and alkyl phosphate.

[0050] In addition, other additives known to those skilled in the art may be added to improve the performance of the electrode paste.

[0051] organic solvents

[0052] The organic solvent can be any solvent known to those skilled in the art, including but not limited to terpineol, dodecyl alcohol, etc.

[0053] Proportional relationship between components

[0054] The slurry comprises 80 to 90 parts by weight of carbon nanotube-microcapsule tungsten powder, 3 to 10 parts by weight of binder phase powder, 5 to 10 parts by weight of organic carrier, 0.5 to 1 part by weight of additives, and 3 to 10 parts by weight of organic solvent. By controlling each component within the above-mentioned parts by weight range, the viscosity of the electrode slurry can be controlled within the range of 80 to 150 Pa·s (at 25°C), thereby increasing the adhesion to the ceramic matrix after high-temperature co-firing.

[0055] <Preparation Method of Electrode Paste>

[0056] The preparation of electrode paste includes the following steps:

[0057] Preparation of carbon nanotube-microcapsule tungsten powder: Tungsten powder is sequentially subjected to acid washing, ethanol purification, wall material liquid preparation, vibration coating, ultrasonic dispersion, washing, drying and sieving; carbon nanotube dispersion is obtained by ultrasonic dispersion using an organic solvent as the dispersion system; microcapsule tungsten powder is mixed with carbon nanotube dispersion, and then subjected to mechanical premixing, ultrasonic dispersion, washing, drying and sieving to obtain integrated carbon nanotube-microcapsule tungsten powder.

[0058] Organic carrier preparation: The resin and solvent are mixed, heated and stirred, and then degassed under vacuum to obtain the organic carrier;

[0059] Finally, the carbon nanotube-microcapsule tungsten powder, binder powder, organic carrier, organic solvent, and additives are mixed, ball-milled, roller-dispersed, and vacuum degassed.

[0060] in:

[0061] The mass ratio of tungsten powder to wall material liquid is 1:2~5, the mass ratio of acetone to hydrogenated terpineol in the wall material liquid is 3~8:1, and the microcapsule tungsten powder passes through a 300-mesh sieve;

[0062] In the carbon nanotube dispersion, the organic solvents are polyvinylpyrrolidone and N-methylpyrrolidone, with a mass ratio of polyvinylpyrrolidone to carbon nanotubes of 2~5:1 and a mass ratio of N-methylpyrrolidone to carbon nanotubes of 50~100:1.

[0063] In the roll dispersion process, a three-roll mill is used, with the discharge roller gaps being 60μm, 40μm, 20μm, 10μm, and 5μm respectively. This step yields an electrode slurry with a fineness ≤5μm. Controlling the fineness within this range can further increase adhesion.

[0064] The above and other advantages of the present invention can be better understood through the following embodiments, but the following embodiments are not intended to limit the scope of the present invention.

[0065] Example

[0066] The following embodiments illustrate the present invention, but the present invention is not limited to the following embodiments.

[0067] Screen printing performance Printing is done using a 325-mesh screen. Visual inspection under an optical microscope is performed to check for overflow, particle agglomeration, missing prints, and serrations in the film. ○○○ indicates excellent film quality, ○○ indicates good film quality, and ○ indicates average film quality.

[0068] Co-firing compatibility: Co-fire with an alumina ceramic substrate at 1550-1750℃ and observe the interface bonding state for defects such as warping, cracking, and detachment; ○○○ indicates excellent co-firing compatibility, ○○ indicates good co-firing compatibility, and ○ indicates average co-firing compatibility.

[0069] Adhesion The test shall be conducted using the cross-cut test method (GB / T 9286-1998).

[0070] Fang Zu The four-probe method was used for testing (GB / T 15519-2017).

[0071] Extremely poor film thickness Tested using a laser confocal microscope (test range 5mm×5mm);

[0072] Oxidation rate After co-firing and sintering, the intensity of the characteristic peaks of WO3 was calculated by X-ray diffraction (XRD).

[0073] Preparation Example 1: Carbon Nanotube-Microcapsule Tungsten Powder A-1

[0074] Preparation of microencapsulated tungsten powder: Take tungsten powder with a particle size <2μm, add 2.5-3 times the volume of tungsten powder in 10wt% dilute hydrochloric acid, ultrasonically disperse at 200W for 30min, let stand for 30min, decant the supernatant, repeat the above operation 3 times to remove impurities on the surface of the tungsten powder; after acid washing, wash the tungsten powder 3 times with pure water, add anhydrous ethanol (solid-liquid mass ratio 1:5), mechanically stir at 300r / min for 2h, then keep warm in a vacuum drying oven at 60℃ for 3h to dry the tungsten powder; weigh polyacrylic acid / ethyl cellulose mixed resin (polyacrylic acid: ethyl cellulose mass ratio 1:2) and acetone / hydrogenated terpineol mixed solvent (acetone: hydrogenated terpineol mass ratio 5:1) at a mass ratio of 1:20, heat in an oil bath at 70℃ and stir at 300r / min for 3h to form a homogeneous wall material liquid; add the purified tungsten powder to the wall material liquid (tungsten powder: The wall material liquid was mixed at a mass ratio of 1:4, and the mixture was oscillated at 200 r / min for 30 min. It was then ultrasonically dispersed at 200 W for 2 h. The uniformity of the coating was observed using an optical microscope. After coating, the mixture was allowed to stand for 30 min, the supernatant was discarded, and the mixture was washed three times with pure water and anhydrous ethanol alternately. The mixture was then vacuum dried at 50℃ for 4 h and graded using a 300-mesh sieve to obtain microcapsule tungsten powder.

[0075] Preparation of carbon nanotube dispersion: Weigh polyvinylpyrrolidone (PVP) and N-methylpyrrolidone (NMP) at a mass ratio of 3:1, stir at 300 r / min for 1 h until completely dissolved to form a dispersion; take single-walled carbon nanotubes with an average diameter of 5 nm, add twice the volume of the above dispersion, and sonicate at 300 W for 2 h to obtain carbon nanotube dispersion (concentration of about 0.5~1 mg / mL).

[0076] Preparation of carbon nanotube-microcapsule tungsten powder: Take microcapsule tungsten powder and add 2.5 to 3 times its volume of deionized water. The mass ratio of carbon nanotubes to microcapsule tungsten powder is 0.2:99.8. Add carbon nanotube dispersion dropwise and stir at 300 r / min for 1 h. Disperse ultrasonically at 200 W for 2 h. After standing for 30 min, decant the supernatant, wash twice with deionized water, vacuum dry at 50℃ for 4 h, and classify through a 300 mesh sieve to obtain carbon nanotube-microcapsule tungsten powder A-1.

[0077] Preparation Example 2: Carbon Nanotube-Microcapsule Tungsten Powder A-2

[0078] The polyacrylic acid in Preparation Example 1 was replaced with a copolymer of acrylic acid and methyl methacrylate, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder A-2.

[0079] Preparation Example 3: Carbon Nanotube-Microcapsule Tungsten Powder A-3

[0080] Ethyl cellulose in Preparation Example 1 was replaced with hydroxypropyl cellulose, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder A-3.

[0081] Preparation Example 4: Carbon Nanotube-Microcapsule Tungsten Powder A-4

[0082] The mass ratio of polyacrylic acid to ethyl cellulose in Preparation Example 1 was changed to 1:3, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder A-4.

[0083] Preparation Example 5: Carbon Nanotube-Microcapsule Tungsten Powder A-5

[0084] The mass ratio of polyacrylic acid to ethyl cellulose in Preparation Example 1 was changed to 1:10, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder A-5.

[0085] Preparation Example 6: Carbon Nanotube-Microcapsule Tungsten Powder A-6

[0086] The average diameter of the single-walled carbon nanotubes in Preparation Example 1 was changed to 3 nm, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder A-6.

[0087] Preparation Example 7: Carbon Nanotube-Microcapsule Tungsten Powder A-7

[0088] The average diameter of the single-walled carbon nanotubes in Preparation Example 1 was changed to 1 nm, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder A-7.

[0089] Preparation Example 8: Carbon Nanotube-Microcapsule Tungsten Powder A-8

[0090] The single-walled carbon nanotubes with an average diameter of 1 nm in Preparation Example 1 were replaced with multi-walled carbon nanotubes with an average diameter of 10 nm, while the rest remained the same as in Preparation Example 1, resulting in carbon nanotube-microcapsule tungsten powder A-8.

[0091] Preparation Example 9: Carbon Nanotube-Microcapsule Tungsten Powder A-9

[0092] The single-walled carbon nanotubes with an average diameter of 1 nm in Preparation Example 1 were replaced with multi-walled carbon nanotubes with an average diameter of 50 nm, while the rest remained the same as in Preparation Example 1, resulting in carbon nanotube-microcapsule tungsten powder A-9.

[0093] Preparation Example 10: Carbon Nanotube-Microcapsule Tungsten Powder A-10

[0094] The single-walled carbon nanotubes with an average diameter of 1 nm in Preparation Example 1 were replaced with a combination of single-walled carbon nanotubes with an average diameter of 2 nm and multi-walled carbon nanotubes with an average diameter of 30 nm in a mass ratio of 1:1. The rest remained the same as in Preparation Example 1, resulting in carbon nanotube-microcapsule tungsten powder A-10.

[0095] Preparation Example 11: Carbon Nanotube-Microcapsule Tungsten Powder A-11

[0096] The mass ratio of carbon nanotubes to microcapsule tungsten powder in Preparation Example 1 was changed from 0.2:99.8 to 1.0:99.0, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder A-11.

[0097] Comparative Preparation Example 1: Carbon Nanotube-Microcapsule Tungsten Powder B-1

[0098] The polyacrylic acid / ethyl cellulose mixed resin in Preparation Example 1 was replaced with polyacrylic acid resin, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder B-1.

[0099] Comparative Preparation Example 2: Carbon Nanotube-Microcapsule Tungsten Powder B-2

[0100] The polyacrylic acid / ethyl cellulose mixed resin in Preparation Example 1 was replaced with ethyl cellulose, while the rest remained the same as in Preparation Example 1, to obtain carbon nanotube-microcapsule tungsten powder B-2.

[0101] Comparative Preparation Example 3: Carbon Nanotube-Microcapsule Tungsten Powder B-3

[0102] The mass ratio of carbon nanotubes to microcapsule tungsten powder in Preparation Example 1 was changed from 0.2:99.8 to 1.5:96.0, while the rest remained the same as in Preparation Example 1, resulting in carbon nanotube-microcapsule tungsten powder B-3.

[0103] Comparative Preparation Example 4: Carbon Nanotube-Microcapsule Tungsten Powder B-4

[0104] The mass ratio of carbon nanotubes to microcapsule tungsten powder in Preparation Example 1 was changed from 0.2:99.8 to 0.05:99.9, while the rest remained the same as in Preparation Example 1, resulting in carbon nanotube-microcapsule tungsten powder B-4.

[0105] Comparative Preparation Example 5: Carbon Nanotube-Tungsten Powder B-5

[0106] Preparation of tungsten powder: Take tungsten powder with a particle size <2μm, add 10wt% dilute hydrochloric acid at 2.5 to 3 times the volume of tungsten powder, disperse by ultrasonication at 200W for 30min, let stand for 30min, decant the supernatant, repeat the above operation 3 times to remove impurities on the surface of tungsten powder; after acid washing, wash the tungsten powder with pure water 3 times, add anhydrous ethanol (solid-liquid mass ratio 1:5), stir mechanically at 300r / min for 2h, and then keep warm in a vacuum drying oven at 60℃ for 3h to dry the tungsten powder.

[0107] Preparation of carbon nanotube dispersion: Weigh polyvinylpyrrolidone (PVP) and N-methylpyrrolidone (NMP) at a mass ratio of 3:1, stir at 300 r / min for 1 h until completely dissolved to form a dispersion; take single-walled carbon nanotubes with an average diameter of 5 nm, add twice the volume of the above dispersion, and sonicate at 300 W for 2 h to obtain carbon nanotube dispersion (concentration of about 0.5~1 mg / mL).

[0108] Preparation of carbon nanotube-tungsten powder: Take tungsten powder and add 2.5 to 3 times its volume of deionized water. The mass ratio of carbon nanotubes to tungsten powder is 0.2:99.8. Add carbon nanotube dispersion dropwise and stir at 300 r / min for 1 h. Disperse by ultrasonication at 200 W for 2 h. After standing for 30 min, decant the supernatant, wash twice with deionized water, vacuum dry at 50℃ for 4 h, and classify by 300 mesh sieve to obtain carbon nanotube-tungsten powder B-5.

[0109] Comparative Preparation Example 6: Microencapsulated Tungsten Powder B-6

[0110] Take tungsten powder with a particle size <2μm, add 2.5-3 times the volume of tungsten powder in 10wt% dilute hydrochloric acid, ultrasonically disperse at 200W for 30min, let stand for 30min, decant the supernatant, and repeat the above operation 3 times to remove impurities on the surface of the tungsten powder; after acid washing, wash the tungsten powder 3 times with pure water, add anhydrous ethanol (solid-liquid mass ratio 1:5), mechanically stir at 300r / min for 2h, and then keep warm in a vacuum drying oven at 60℃ for 3h to dry the tungsten powder; weigh polyacrylic acid / ethyl cellulose mixed resin (polyacrylic acid: ethyl cellulose mass ratio 1:2) and acetone / hydrogenated terpineol mixed solvent (acetone: hydrogenated terpineol mass ratio 5:1) at a mass ratio of 1:20, heat in an oil bath at 70℃ and stir at 300r / min for 3h to form a homogeneous wall material liquid; add the purified tungsten powder to the wall material liquid (tungsten powder: The wall material liquid was mixed at a mass ratio of 1:4, and the mixture was oscillated at 200 r / min for 30 min. It was then ultrasonically dispersed at 200 W for 2 h. The uniformity of the coating was observed using an optical microscope. After coating, the mixture was allowed to stand for 30 min, the supernatant was discarded, and the mixture was washed three times alternately with pure water and anhydrous ethanol. The mixture was then vacuum dried at 50℃ for 4 h and graded using a 300-mesh sieve to obtain microcapsule tungsten powder B-6.

[0111] Example 1

[0112] Take 85 parts by weight of carbon nanotube-microcapsule tungsten powder A-1, 5 parts by weight of binder powder (alumina powder, calcium oxide, yttrium oxide, silica, kaolin, and talc powder in a mass ratio of 99:1.0:0.05:0.1:0.05:0.04), 6 parts by weight of organic carrier (resin is a mixture of pure acrylic resin and ethyl cellulose in a mass ratio of 3:1, solvent is terpineol, and the mass ratio of resin to solvent is 1:5), 0.6 parts by weight of additives, and 10 parts by weight of a mixture of terpineol and terpineol ester in a mass ratio of 3:2 as organic solvent. The additives are 0.2 parts by weight of thixotropic agent polyamide wax, 0.2 parts by weight of leveling agent polydimethylsiloxane, 0.1 parts by weight of defoamer polyether-modified polydimethylsiloxane, and 0.1 parts by weight of dispersant sorbitan monooleate. Add them sequentially to the sample container, mix them evenly with a mixer, and then perform preliminary pre-dispersion using a mortar. The pre-dispersed slurry was finely dispersed by a three-roll mill to finally obtain SL-1, a tungsten-based printed electrode slurry synergistically modified with microcapsule coating and carbon nanotube doping, with a viscosity of 135 Pa·s.

[0113] Examples 2 to 11

[0114] In Example 1, tungsten powder A-1 was replaced sequentially with tungsten powders A-2 to A-11, while the rest remained the same as in Example 1, resulting in electrode slurries SL-2 to SL-11.

[0115] Comparative Examples 1 to 6

[0116] In Example 1, tungsten powder A-1 was replaced with tungsten powders B-1 to B-6 in sequence, and the rest was the same as in Example 1, to obtain electrode slurries SL-a to SL-f respectively.

[0117] Comparative Example 7

[0118] In Example 1, tungsten powder A-1 was replaced with B-6, and single-walled carbon nanotubes with an average diameter of 1 nm were added. The mass ratio of carbon nanotubes to microcapsule tungsten powder was 0.2:99.8, resulting in electrode slurry SL-g.

[0119] The viscosity of the prepared electrode pastes was tested, and the viscosity ranged from 95 to 140 Pa·s. Then, a custom pattern was printed onto a ceramic substrate using a 325-mesh screen printing plate. The screen printing capability of each paste was evaluated. The printed substrates were co-fired under a nitrogen-hydrogen mixed gas at a temperature >1600℃. After firing, the co-firing compatibility, adhesion, sheet resistance, film thickness difference, and oxidation rate of the electrode film were tested. The test results are shown in Table 1 below.

[0120] Table 1

[0121] Electrode paste Screen printing performance Co-firing compatibility Adhesion (MPa) Shear resistance (mΩ / □) Film thickness range (μm) Oxidation rate (%) Example 1 SL-1 ○○ ○○ 15.8 26 1.8 1.1 Example 2 SL-2 ○○ ○○○ 17.8 22 1.2 1.4 Example 3 SL-3 ○○○ ○○ 16.5 24 1.6 1.3 Example 4 SL-4 ○○○ ○○○ 16.3 23 1.7 1.3 Example 5 SL-5 ○○○ ○○○ 16.6 25 1.4 1.1 Example 6 SL-6 ○○○ ○○○ 17.2 21 1.5 1.2 Example 7 SL-7 ○○○ ○○○ 17.0 22 1.6 1.1 Example 8 SL-8 ○○○ ○○○ 16.3 24 1.6 0.8 Example 9 SL-9 ○○○ ○○○ 16.1 20 1.4 1.5 Example 10 SL-10 ○○○ ○○○ 16.4 27 1.3 1.4 Example 11 SL-11 ○○ ○○○ 17.8 24 1.4 1.2 Comparative Example 1 SL-a ○ ○ 10.9 28 2.3 1.9 Comparative Example 2 SL-b ○ ○ 11.2 27 1.9 1.7 Comparative Example 3 SL-c ○○ ○○ 7.8 23 3.7 1.3 Comparative Example 4 SL-d ○○ ○○ 10.4 35 2.1 1.8 Comparative Example 5 SL-e ○○ ○○ 11.2 50 1.9 2.4 Comparative Example 6 SL-f ○ ○○ 11.1 40 2.0 2.9 Comparative Example 7 SL-g ○○ ○○ 10.8 30 2.2 1.7

[0122] It should be noted that, based on the explanations and descriptions in the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some equivalent modifications and alterations to the present invention should also be within the scope of protection of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the invention.

Claims

1. An electrode slurry, characterized by, The slurry comprises carbon nanotube-microcapsule tungsten powder; The carbon nanotube-microcapsule tungsten powder includes carbon nanotubes and microcapsule tungsten powder. The core of the microcapsule tungsten powder is tungsten powder, and the wall material is a mixture including a first resin and a second resin; The first resin includes an acrylic resin, and the second resin includes a cellulose ether; The mass ratio of carbon nanotubes to microcapsule tungsten powder in the carbon nanotube-microcapsule tungsten powder is (0.1 ~ 1.25):(98.75 ~ 99.9).

2. The electrode paste according to claim 1, characterized in that, In the wall material, the mass ratio of the mixture of the first resin and the second resin is 1:3~10.

3. The electrode paste according to claim 1, characterized in that, The acrylic resin includes one or more of the homopolymers or copolymers formed by polymerizing acrylic acid, methacrylic acid and their ester monomers, and the cellulose ether includes one or more of methylcellulose, ethylcellulose, hydroxypropylcellulose, and hydroxyethylcellulose.

4. The electrode paste according to claim 1, characterized in that, The carbon nanotubes are selected from single-walled carbon nanotubes and multi-walled carbon nanotubes. The average diameter of the single-walled carbon nanotubes is 1 to 3 nm, and the average diameter of the multi-walled carbon nanotubes is 10 to 50 nm.

5. The electrode paste according to claim 4, characterized in that, The carbon nanotubes are a combination of single-walled carbon nanotubes and multi-walled carbon nanotubes.

6. The electrode paste according to any one of claims 1 to 5, characterized in that, The electrode paste comprises 80 to 90 parts by weight of carbon nanotube-microcapsule tungsten powder, 3 to 10 parts by weight of binder powder, 5 to 10 parts by weight of organic carrier, 0.5 to 1 part by weight of additives, and 3 to 10 parts by weight of organic solvent.

7. The electrode paste according to claim 6, characterized in that, The binder phase powder comprises 98.0~99.5 wt% alumina and 0.4~1.6 wt% calcium oxide.

8. The electrode paste according to claim 6, characterized in that, The organic carrier comprises a resin and a solvent in a mass ratio of 1:3 to 8, wherein the resin comprises a mixture of acrylic resin and ethyl cellulose in a mass ratio of 1 to 5:1, and the solvent is selected from at least one of the following systems: terpineol, dodecyl alcohol ester, and dioctyl phthalate.

9. A method for preparing the electrode paste according to any one of claims 1 to 8, characterized in that, The integrated preparation of carbon nanotube-microcapsule tungsten powder includes: tungsten powder is coated by oscillation of wall material liquid to obtain microcapsule tungsten powder, which is then mixed with carbon nanotube dispersion to obtain carbon nanotube-microcapsule tungsten powder.

10. The method for preparing the electrode paste according to claim 9, characterized in that, The mass ratio of tungsten powder to the wall material liquid is 1:2~5, and the mass ratio of acetone to hydrogenated terpineol in the wall material liquid is 3~8:

1. In the carbon nanotube dispersion, the organic solvents are polyvinylpyrrolidone and N-methylpyrrolidone, the mass ratio of polyvinylpyrrolidone to carbon nanotubes is 2~5:1, and the mass ratio of N-methylpyrrolidone to carbon nanotubes is 50~100:1.