Manufacturing method for modified nickel paste for MLCC

Abstract

This application relates to the field of electronic materials for multilayer ceramic chip capacitors, specifically to a method for manufacturing a modified nickel paste for MLCCs. The method includes a nano-BaTiO3 pre-dispersion step in which nano-BaTiO3 powder, a diluent, and a dispersant are uniformly mixed and dispersed in a specific mass ratio to obtain a nano-BaTiO3 pre-dispersion, and a modified nickel paste for MLCCs is obtained by mixing the BaTiO3 pre-dispersion, adhesive, dispersant, diluent, and nickel powder in a specific mass ratio, dispersing, and filtering the mixture to obtain a modified nickel paste for MLCCs. This application first pre-disperses the nano-BaTiO3 powder with a dispersant to obtain a uniformly dispersed nano-BaTiO3 pre-dispersion, and then mixes the nano-BaTiO3 pre-dispersion with nickel powder and other raw materials in the above proportions and disperses the mixture in a three-roll mill to obtain a uniformly dispersed nickel paste, thereby solving the problem of non-uniform dispersion of nano-BaTiO3 powder in nickel paste for MLCCs.

Description

[Technical Field]

[0001] This application relates to the field of electronic materials for multilayer ceramic chip capacitors, and more particularly to a method for producing modified nickel paste for MLCCs. [Background technology]

[0002] MLCC (Multi-layer Ceramic Capacitor) is an English abbreviation for multilayer ceramic chip capacitor. MLCCs are also called monolithic ceramic capacitors because they are made by stacking ceramic dielectric diaphragms with printed electrodes (internal electrodes) and sintering them at high temperature all at once to form a ceramic chip, and then sealing both ends of the chip with metal layers (external electrodes), forming a structure similar to a monolith.

[0003] Currently, the paste used for MLCC internal electrodes is typically nickel paste. Related technologies produce nickel paste by mixing nickel powder, nano-BaTiO3, adhesive, dispersant, and organic solvent, and then dispersing the materials using the pressure, gap, and friction shear forces of a triple-roll mill. However, because the particle size of nano-BaTiO3 powder is smaller than that of nickel powder, the gap of the triple-roll mill must be adjusted to be small to ensure the dispersion of the nano-BaTiO3, which breaks down the larger-sized nickel powder. The gap of the triple-roll mill must be adjusted to be large to ensure the dispersion of the nickel powder, which causes the smaller-sized nano-BaTiO3 to aggregate, resulting in poor dispersion. Because nickel powder dispersibility is crucial for MLCC nickel paste, nano-BaTiO3 typically results in poor dispersion, resulting in holes and discontinuities in the MLCC internal electrodes, further affecting the performance of the finished MLCC.

[0004] Therefore, there is an urgent need to improve the dispersion performance of nano-BaTiO3 powder in nickel paste to improve the performance of the finished MLCC products. Summary of the Invention [Problem to be solved by the invention]

[0005] To solve the problem of nano-BaTiO3 powder not being uniformly dispersed in nickel paste for MLCC, the present application provides a method for manufacturing modified nickel paste for MLCC. [Means for solving the problem]

[0006] In a first aspect, the present application provides a method for producing a modified nickel paste for MLCC, which uses the following technical means:

[0007] The manufacturing method of modified nickel paste for MLCC is as follows: a nano-BaTiO3 pre-dispersion step in which the nano-BaTiO3 powder, diluent, and dispersant are uniformly mixed and dispersed in a mass ratio of (60-90):(20-30):1 to obtain a nano-BaTiO3 pre-dispersion; and a nickel paste preparation step of mixing BaTiO3 pre-dispersion, adhesive, dispersant, diluent, and nickel powder in a mass ratio of 10:(10~15):(0.1~1):(10~15):(25~60), dispersing, and filtering to obtain a modified nickel paste for MLCC.

[0008] According to the above technical means, the nano-BaTiO3 powder is first pre-dispersed with a dispersant to obtain a uniformly dispersed nano-BaTiO3 pre-dispersion, and then the nano-BaTiO3 pre-dispersion is mixed with nickel powder and other raw materials in the above proportions and dispersed in a three-roll mill to obtain a uniformly dispersed nickel paste, thereby solving the problem of the nano-BaTiO3 powder not being uniformly dispersed in the nickel paste for MLCCs and improving the performance of the finished MLCC products.

[0009] Preferably, the mass ratio of the BaTiO3 pre-dispersion to the nickel powder is 10:(50-60).

[0010] Preferably, the particle size of the nano BaTiO3 powder is 10 to 200 nm.

[0011] According to the above technical means, when the particle size of the nano BaTiO3 powder is within the above range, the dispersion performance of the nano BaTiO3 powder in the nickel paste is excellent.

[0012] Preferably, the method for producing the adhesive comprises: a step of preparing a terminal epoxy group hyperbranched polyester by reacting a terminal hydroxyl group hyperbranched polyester with epichlorohydrin in a mass ratio of (10-20:1) to obtain a terminal epoxy group hyperbranched polyester; a modified polyvinyl butyral preparation step of reacting a terminal epoxy group hyperbranched polyester with polyvinyl butyral in a mass ratio of (10-25):1 to obtain a modified polyvinyl butyral; and an adhesive production step of reacting modified polyvinyl butyral and ethyl cellulose in a mass ratio of (2-10:1) to obtain an adhesive.

[0013] According to the above technical means, the hydroxyl-terminated hyperbranched polyester is reacted with epichlorohydrin in the above mass ratio to obtain an epoxy-terminated hyperbranched polyester, and then an excess of the epoxy-terminated hyperbranched polyester is reacted with polyvinyl butyral. In this process, the epoxy groups on the epoxy-terminated hyperbranched polyester react with the hydroxyl groups on the polyvinyl butyral to form ether bonds with the hydroxyl groups, thereby obtaining a modified polyvinyl butyral. The modified polyvinyl butyral contains unreacted epoxy groups, and the modified polyvinyl butyral is then reacted with ethyl cellulose, where the epoxy groups on the modified polyvinyl butyral react with the hydroxyl groups on the ethyl cellulose to form ether bonds with the hydroxyl groups.

[0014] As can be seen from the above, ethyl cellulose is grafted onto polyvinyl butyral molecules using epoxy-terminated hyperbranched polyester as a bridge to obtain an adhesive containing multiple active groups. This adhesive is then added to the nickel paste, and some of the active groups in the adhesive cross-link with each other, firmly adhering the components together. Other active groups bond with hydroxyl groups in the ceramic coating layer, thereby providing good adhesion between the nickel paste and the ceramic coating layer, thereby improving the performance of the finished MLCC.

[0015] Preferably, the mass ratio of the epoxy-terminated hyperbranched polyester to polyvinyl butyral is (10-15):1.

[0016] Preferably, the diluent is one or more of terpineol, isobornyl acetate, isophorone, and butyl acetate.

[0017] Preferably, the diluent is a mixture of terpineol, isobornyl acetate, and butyl acetate in a mass ratio of (0.2-1):(0.5-1.5):1.

[0018] According to the above technical means, by adding a diluent composed of terpineol, isobornyl acetate, and butyl acetate in the above specific mass ratio to the nickel paste, the effect on the ceramic coating layer is small, and the possibility of the diluent destroying the ceramic coating layer is reduced.

[0019] Preferably, the nickel powder is synthesized by a chemical method, and the raw materials for the nickel powder include nickel sulfate and other metal salts, and the other metal salts are one or more of chromium sulfate, copper sulfate, and silver sulfate.

[0020] According to the above technical means, nickel powder is doped with other metals and sulfur to impart good pressure resistance and high temperature resistance to the nickel powder, and this nickel powder is used as a raw material to produce nickel paste, which can then be used to manufacture MLCCs, thereby producing finished MLCCs with good voltage resistance and high temperature resistance.

[0021] Preferably, the nickel powder is synthesized by physical vapor deposition, and the raw materials for the nickel powder include a nickel target, sulfur powder, and another metal target, and the other metal target is one or more of a chromium target, a copper target, and a silver target.

[0022] According to the above technical means, nickel powder is doped with other metals and sulfur to impart good pressure resistance and high temperature resistance to the nickel powder, and this nickel powder is used as a raw material to produce nickel paste, which can then be used to manufacture MLCCs, thereby producing finished MLCCs with good voltage resistance and high temperature resistance. [Effects of the Invention]

[0023] From the above, the present application has the following beneficial effects.

[0024] 1. In this application, nano-BaTiO3 powder is pre-dispersed with a dispersant to obtain a uniformly dispersed nano-BaTiO3 pre-dispersed material, and then the nano-BaTiO3 pre-dispersed material is mixed and dispersed with nickel powder and other raw materials in a specific ratio to obtain a uniformly dispersed nickel paste, thereby solving the problem of nano-BaTiO3 powder not being uniformly dispersed in nickel paste for MLCCs and improving the performance of the finished MLCC products.

[0025] 2. In this application, ethyl cellulose is grafted onto polyvinyl butyral molecules using a terminal epoxy hyperbranched polyester as a bridge to obtain an adhesive containing multiple active groups. This adhesive is then added to the nickel paste, and some of the active groups in the adhesive cross-link with each other to firmly bond the components together, while other active groups bond with the hydroxyl groups in the ceramic coating layer, thereby providing good adhesion between the nickel paste and the ceramic coating layer and improving the performance of the finished MLCC.

[0026] 3. In this application, nickel powder is modified, sulfur and other metals are added to the nickel powder, and the modified nickel powder is used as a raw material to produce nickel paste. The nickel paste is then used to manufacture MLCCs, which can produce finished MLCCs with good voltage resistance and high temperature resistance. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is an SEM image of Example 23 of the present application. [Figure 2] FIG. 1 is an SEM image of Example 24 of the present application. [Figure 3] FIG. 1 is an SEM image of Example 25 of the present application. [Figure 4] FIG. 1 is an SEM image of Example 26 of the present application. [Figure 5] FIG. 1 is an SEM image of Example 27 of the present application. [Figure 6] FIG. 1 is an SEM image of Example 28 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will now be described in more detail with reference to examples.

[0029] Unless otherwise specified, the specifications of raw materials used in the following examples and comparative examples refer to Table 1 (Raw Material Specifications Information).

[0030] [Table 1]

[0031] Adhesive manufacturing example Manufacturing Example 1 The adhesive was prepared according to the following steps.

[0032] In the epoxy-terminated hyperbranched polyester preparation step, 10 kg of hydroxyl-terminated hyperbranched polyester and 20 kg of DMF are mixed uniformly, heated to 60°C, nitrogen gas is introduced, 1 kg of epichlorohydrin is added, and the mixture is allowed to react for 3 hours. The mixture is then cooled to 30°C, 550 g of saturated sodium hydroxide solution is added, and the mixture is kept at a constant temperature for 3 hours. 500 g of dichloromethane is added, and the mixture is washed with water three times and dried to obtain epoxy-terminated hyperbranched polyester. In the modified polyvinyl butyral preparation step, 5 kg of the above-mentioned epoxy-terminated hyperbranched polyester and 10 kg of DMF are mixed, heated to 50°C, 0.5 kg of polyvinyl butyral is added, and the mixture is kept warm for 5 hours and dried to obtain modified polyvinyl butyral. In the adhesive preparation step, 2 kg of the modified polyvinyl butyral prepared above and 5 kg of DMF were mixed, heated to 65°C, and 1 kg of ethyl cellulose was added. The mixture was kept warm for 8 hours and dried to obtain the adhesive.

[0033] Manufacturing Examples 2-3 The difference between the adhesive and Production Example 1 is that the amounts of some materials used in the adhesive production process are different, and the specific amounts used are shown in Table 2 (masses of some materials used in the adhesive production process).

[0034] [Table 2]

[0035] Nickel powder manufacturing example Manufacturing example a The nickel powder was produced according to the following steps S1 to S3.

[0036] In S1, for the preparation of the mixed solution, 10 kg of nickel nitrate and 2 kg of sodium citrate dihydrate were weighed and dissolved in 40 L of deionized water. In S2, for the preparation of the reducing solution, 6.5 kg of 80% hydrazine hydrate was weighed, 8 kg of sodium hydroxide, 1 kg of triethanolamine and 120 L of deionized water were added, and the mixture was stirred to dissolve. In S3, the mixed solution was placed in a water bath at 80°C, and the reducing solution was added dropwise to the mixed solution. After reacting for 10 minutes, the solution began to turn gray and bubbles gradually formed. 1.2 kg of triethanolamine and 0.1 kg of dimethylpolysiloxane antifoaming agent were added, and the reaction was continued for 30 minutes, after which the reaction was stopped and cooled. The mixture was left to stand overnight, and the supernatant was removed. After washing, it was dried in a vacuum oven at 70°C to obtain nickel powder.

[0037] Manufacturing example b The difference between the nickel powder and Production Example a is that 10 kg of nickel nitrate was changed to 9.5 kg of nickel sulfate hexahydrate + 0.2 kg of copper sulfate + 0.3 kg of silver sulfate.

[0038] Manufacturing example c The nickel powder was produced according to the following steps S1 to S4.

[0039] In S1, a 10 kg nickel target is selected and placed in the reactor. In S2, nitrogen gas is filled into the reactor, and the pressure per unit area in the reactor is controlled to 100 kPa. In step S3, an arc is generated by ignition, and the arc is burned between the plasma gun and the nickel until the nickel particles are completely melted, and the magnitude of the current of the plasma gun is controlled. In S4, the magnitude of the current of the plasma gun is increased and controlled until the nickel particles gradually evaporate into particulate nickel, enter the condenser, and form nickel powder in a collector connected to the condenser.

[0040] Manufacturing example d The nickel powder was produced according to the following steps S1 to S4.

[0041] In S1, 9.8 kg of nickel target, 0.1 kg of sulfur powder, and 0.1 kg of chromium target were selected and loaded into the reactor. In S2, nitrogen gas is filled into the reactor, and the pressure per unit area in the reactor is controlled to 100 kPa. In step S3, an arc is generated by ignition, and the arc is burned between the plasma gun and the nickel until the nickel particles are completely melted, and the magnitude of the current of the plasma gun is controlled. In S4, the magnitude of the current of the plasma gun is increased and controlled until the nickel particles gradually evaporate into particulate nickel, enter the condenser, and form nickel powder in a collector connected to the condenser.

[0042] Diluent manufacturing example Manufacturing example A The diluent was prepared according to the following steps.

[0043] 2 kg of electronic grade terpineol, 5 kg of electronic grade isobornyl acetate, and 10 kg of electronic grade butyl acetate were uniformly mixed to prepare a diluent.

[0044] Manufacturing example B The diluent was prepared according to the following steps.

[0045] 4.85 kg of electronic grade terpineol, 7.3 kg of electronic grade isobornyl acetate, and 4.85 kg of electronic grade butyl acetate were uniformly mixed to prepare a diluent.

[0046] Manufacturing example C The diluent was prepared according to the following steps.

[0047] A diluent was prepared by uniformly mixing 1.1 kg of electronic grade terpineol, 5.3 kg of electronic grade isobornyl acetate, and 10.6 kg of electronic grade butyl acetate.

[0048] Manufacturing example D The diluent was prepared according to the following steps.

[0049] 2.4 kg of electronic grade terpineol, 2.4 kg of electronic grade isobornyl acetate, and 12.2 kg of electronic grade butyl acetate were uniformly mixed to prepare a diluent.

[0050] Manufacturing Example E The diluent was prepared according to the following steps.

[0051] 7.6 kg of electronic grade terpineol, 3.1 kg of electronic grade isobornyl acetate, and 6.3 kg of electronic grade butyl acetate were uniformly mixed to prepare a diluent.

[0052] Manufacturing example F The diluent was prepared according to the following steps.

[0053] 1.1 kg of electronic grade terpineol, 10.6 kg of electronic grade isobornyl acetate, and 5.3 kg of electronic grade butyl acetate were uniformly mixed to prepare a diluent.

[0054] Manufacturing example G The difference from Production Example A is that the diluent in this production example is 17 kg of electronics-grade terpineol.

[0055] Manufacturing example H The difference from Production Example A is that the diluent in this production example is 17 kg of electronics grade isobornyl acetate.

[0056] Manufacturing example I The difference from Preparation A is that the diluent in this preparation is 17 kg of electronic grade butyl acetate.

[0057] Example Example 1 The modified nickel paste for MLCC was prepared according to the following steps.

[0058] In the nano-BaTiO3 pre-dispersion step, 6 kg of nano-BaTiO3 powder with a particle size of 10 nm was mixed with 2 kg of diluent prepared in Example A and 0.1 kg of dispersant, and the mixture was stirred in a mixer for 30 minutes to achieve uniform mixing. The mixture was then ground and dispersed in a three-roll mill to obtain nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were as follows: (1) the rotation speed ratio of the three rolls was 1:3:9, and the rotation speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 50 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure between the scraper and the rolls was 1 bar; and (5) the number of grinding times was 5. In the nickel paste preparation step, 1 kg of BaTiO3 pre-dispersion, 1 kg of adhesive prepared in Preparation Example 1, 0.01 kg of dispersant, 1 kg of diluent prepared in Preparation Example A, and 3 kg of nickel powder prepared in Preparation Example a are mixed to obtain a mixture, and the mixture is placed in a planetary mixer to pre-mix. The mixed nickel paste is placed in a three-roll mill to be pulverized and dispersed, and the dispersed nickel paste is filtered under pressure, the pore size of the filter element is 15 μm, and the pressure is 10 kPa. Finally, a modified nickel paste for MLCC is obtained. The rotation speed of the dispersion disc in the planetary mixer is 100 r / min, the rotation speed of the central shaft disc is 200 r / min, the vacuum pressure is 10 kPa, and the mixing time is 60 min. When dispersing the nickel paste, the process parameters of the three-roll mill were as follows: (1) the rotational speed ratio of the three rolls was 1:3:9, and the rotational speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 100 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure of the scraper and rolls was 2 bar; and (5) the number of grinding operations was 5.

[0059] Example 2 This is a modified nickel paste for MLCC, and the difference from Example 1 is that a different adhesive was selected. In this example, the adhesive produced in Production Example 2 was selected.

[0060] Example 3 This is a modified nickel paste for MLCC, and the difference from Example 1 is that a different adhesive was selected. In this example, the adhesive produced in Production Example 3 was selected.

[0061] Example 4 This is a modified nickel paste for MLCC, and the difference from Example 1 is that a different adhesive was used. In this example, the adhesive produced in Example 1 was replaced with polyvinyl butyral at an equal mass.

[0062] Example 5 This is a modified nickel paste for MLCC, and the difference from Example 1 is that a different adhesive was used. In this example, the adhesive produced in Example 1 was replaced with ethyl cellulose at an equal mass.

[0063] Example 6 The modified nickel paste for MLCC was prepared according to the following steps.

[0064] In the nano-BaTiO3 pre-dispersion step, 6.02 kg of nano-BaTiO3 powder with a particle size of 10 nm was mixed with 2.01 kg of diluent prepared in Preparation Example A and 0.07 kg of dispersant. After uniform mixing, the mixture was dispersed in a three-roll mill to obtain a nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were the same as those in Example 1. In the nickel paste preparation step, 0.85 kg of BaTiO3 pre-dispersion, 1.27 kg of adhesive prepared in Preparation Example 1, 0.08 kg of dispersant, 1.27 kg of diluent prepared in Preparation Example A, and 2.54 kg of nickel powder prepared in Preparation Example a were mixed to obtain a mixture, which was then placed in a planetary mixer for pre-mixing. The mixed nickel paste was then placed in a three-roll mill for dispersion, and the dispersed nickel paste was filtered under pressure to obtain a modified nickel paste for MLCC. The filter element specifications, planetary mixer process parameters, and three-roll mill process parameters were all the same as in Example 1.

[0065] Example 7 The modified nickel paste for MLCC was prepared according to the following steps.

[0066] In the nano-BaTiO3 pre-dispersion step, 6.08 kg of nano-BaTiO3 powder with a particle size of 10 nm was mixed with 1.94 kg of diluent prepared in Preparation Example A and 0.08 kg of dispersant. After uniform mixing, the mixture was dispersed in a three-roll mill to obtain a nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were the same as those in Example 1. In the nickel paste preparation step, 0.94 kg of BaTiO3 pre-dispersion, 1.25 kg of adhesive prepared in Preparation Example 1, 0.06 kg of dispersant, 1.25 kg of diluent prepared in Preparation Example A, and 2.51 kg of nickel powder prepared in Preparation Example a were mixed to obtain a mixture, which was then placed in a planetary mixer for pre-mixing. The mixed nickel paste was then placed in a three-roll mill for dispersion, and the dispersed nickel paste was filtered under pressure to obtain a modified nickel paste for MLCC. The filter element specifications, planetary mixer process parameters, and three-roll mill process parameters were all the same as in Example 1.

[0067] Example 8 This is a modified nickel paste for MLCC. The difference from Example 1 is that the masses of the BaTiO3 pre-dispersion, adhesive, dispersant, diluent, and nickel powder in the nickel paste preparation step are different. In this example, the masses of these materials are 0.75 kg, 0.75 kg, 0.01 kg, 0.75 kg, and 3.75 kg, respectively.

[0068] Example 9 This is a modified nickel paste for MLCC. The difference from Example 1 is that the masses of the BaTiO3 pre-dispersion, adhesive, dispersant, diluent, and nickel powder in the nickel paste preparation step are different. In this example, the masses of these materials are 0.667 kg, 0.667 kg, 0.007 kg, 0.667 kg, and 4.002 kg, respectively.

[0069] Example 10 This is a modified nickel paste for MLCC, and differs from Example 1 in that the particle size of the nano BaTiO3 powder is different, and in this example, the particle size of the nano BaTiO3 powder is 200 nm.

[0070] Examples 11 to 18 This is a modified nickel paste for MLCC, and the difference from Example 1 is that the source of the diluent is different, and the specific source is shown in Table 3 below (source of diluent).

[0071] [Table 3]

[0072] Example 19 This is a modified nickel paste for MLCC, and differs from Example 1 in that the source of the nickel powder is different. In this example, the nickel powder produced in Production Example a was replaced with the nickel powder produced in Production Example b in an equal mass.

[0073] Example 20 This is a modified nickel paste for MLCC, and differs from Example 1 in that the source of the nickel powder is different. In this example, the nickel powder produced in Production Example a was replaced by the nickel powder produced in Production Example c in an equal mass.

[0074] Example 21 This is a modified nickel paste for MLCC, and differs from Example 1 in that the source of nickel powder is different. In this example, the nickel powder produced in Production Example a was replaced by the nickel powder produced in Production Example d in an equal mass.

[0075] Example 22 This is a modified nickel paste for MLCC, and the difference from Example 1 is that a different adhesive was used. In this example, the adhesive was a blend of 0.5 kg of polyvinyl butyral and 0.5 kg of ethyl cellulose.

[0076] Example 23 The modified nickel paste for MLCC was prepared according to the following steps.

[0077] In the nano-BaTiO3 pre-dispersion step, 750 g of nano-BaTiO3 powder with a particle size of 150 nm was mixed with 240 g of diluent prepared in Preparation Example A and 10 g of dispersant, and the mixture was stirred in a mixer for 30 minutes to achieve uniform mixing. The mixture was then ground and dispersed in a three-roll mill to obtain nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were as follows: (1) the rotation speed ratio of the three rolls was 1:3:9, and the rotation speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 50 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure between the scraper and the rolls was 1 bar; and (5) the number of grinding times was 5. In the nickel paste preparation step, the above-mentioned BaTiO3 pre-dispersion, the adhesive prepared in Preparation Example 1, the dispersant DISPERBYK-108, the diluent prepared in Preparation Example A, and the nickel powder with a particle size of 600 nm prepared in Preparation Example b were mixed in a mass ratio of 20:20:1:20:50 (the mass of the BaTiO3 pre-dispersion was 600 g) to obtain a mixture, which was then pre-mixed in a planetary mixer. The mixed nickel paste was then crushed and dispersed in a three-roll mill, and the dispersed nickel paste was filtered under pressure, with the pore size of the filter element set to 15 μm and the pressure set to 10 kPa. Finally, a modified nickel paste for MLCC was obtained. The rotation speed of the dispersion disc in the planetary mixer is 100 r / min, the rotation speed of the central shaft disc is 200 r / min, the vacuum pressure is 10 kPa, and the mixing time is 60 min. When dispersing the nickel paste, the process parameters of the three-roll mill were as follows: (1) the rotational speed ratio of the three rolls was 1:3:9, and the rotational speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 100 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure of the scraper and rolls was 2 bar; and (5) the number of grinding operations was 5.

[0078] Example 24 The modified nickel paste for MLCC was prepared according to the following steps.

[0079] In the nano-BaTiO3 pre-dispersion step, 750 g of nano-BaTiO3 powder with a particle size of 100 nm was mixed with 240 g of diluent prepared in Preparation Example A and 10 g of dispersant, and the mixture was stirred in a mixer for 30 minutes to achieve uniform mixing. The mixture was then ground and dispersed in a three-roll mill to obtain nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were as follows: (1) the rotation speed ratio of the three rolls was 1:3:9, and the rotation speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 50 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure between the scraper and the rolls was 1 bar; and (5) the number of grinding times was 5. In the nickel paste preparation step, the above-mentioned BaTiO3 pre-dispersion, the adhesive prepared in Preparation Example 1, the dispersant DISPERBYK-108, the diluent prepared in Preparation Example A, and the nickel powder having a particle size of 400 nm prepared in Preparation Example b were mixed in a mass ratio of 20:20:1:20:50 (the mass of the BaTiO3 pre-dispersion was 600 g) to obtain a mixture, which was then pre-mixed in a planetary mixer. The mixed nickel paste was then crushed and dispersed in a three-roll mill, and the dispersed nickel paste was filtered under pressure, with the pore size of the filter element set to 15 μm and the pressure set to 10 kPa. Finally, a modified nickel paste for MLCC was obtained. The rotation speed of the dispersion disc in the planetary mixer is 100 r / min, the rotation speed of the central shaft disc is 200 r / min, the vacuum pressure is 10 kPa, and the mixing time is 60 min. When dispersing the nickel paste, the process parameters of the three-roll mill were as follows: (1) the rotational speed ratio of the three rolls was 1:3:9, and the rotational speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 100 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure of the scraper and rolls was 2 bar; and (5) the number of grinding operations was 5.

[0080] Example 25 The modified nickel paste for MLCC was prepared according to the following steps.

[0081] In the nano-BaTiO3 pre-dispersion step, 750 g of nano-BaTiO3 powder with a particle size of 80 nm was mixed with 240 g of diluent prepared in Preparation Example A and 10 g of dispersant, and the mixture was stirred in a mixer for 30 minutes to achieve uniform mixing. The mixture was then ground and dispersed in a three-roll mill to obtain nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were as follows: (1) the rotation speed ratio of the three rolls was 1:3:9, and the rotation speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 50 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure between the scraper and the rolls was 1 bar; and (5) the number of grinding times was 5. In the nickel paste preparation step, the above-mentioned BaTiO3 pre-dispersion, the adhesive prepared in Preparation Example 1, the dispersant DISPERBYK-108, the diluent prepared in Preparation Example A, and the nickel powder having a particle size of 400 nm prepared in Preparation Example b were mixed in a mass ratio of 20:20:1:20:50 (the mass of the BaTiO3 pre-dispersion was 600 g) to obtain a mixture, which was then pre-mixed in a planetary mixer. The mixed nickel paste was then crushed and dispersed in a three-roll mill, and the dispersed nickel paste was filtered under pressure, with the pore size of the filter element set to 15 μm and the pressure set to 10 kPa. Finally, a modified nickel paste for MLCC was obtained. The rotation speed of the dispersion disc in the planetary mixer is 100 r / min, the rotation speed of the central shaft disc is 200 r / min, the vacuum pressure is 10 kPa, and the mixing time is 60 min. When dispersing the nickel paste, the process parameters of the three-roll mill were as follows: (1) the rotational speed ratio of the three rolls was 1:3:9, and the rotational speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 100 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure of the scraper and rolls was 2 bar; and (5) the number of grinding operations was 5.

[0082] Example 26 The modified nickel paste for MLCC was prepared according to the following steps.

[0083] In the nano-BaTiO3 pre-dispersion step, 750 g of nano-BaTiO3 powder with a particle size of 60 nm was mixed with 240 g of diluent prepared in Preparation Example A and 10 g of dispersant, and the mixture was stirred in a mixer for 30 minutes to achieve uniform mixing. The mixture was then ground and dispersed in a three-roll mill to obtain a nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were as follows: (1) the rotation speed ratio of the three rolls was 1:3:9, and the rotation speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 50 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure between the scraper and the rolls was 1 bar; and (5) the number of grinding times was 5. In the nickel paste preparation step, the above-mentioned BaTiO3 pre-dispersion, the adhesive prepared in Preparation Example 1, the dispersant DISPERBYK-108, the diluent prepared in Preparation Example A, and the nickel powder having a particle size of 300 nm prepared in Preparation Example b were mixed in a mass ratio of 20:20:1:20:50 (the mass of the BaTiO3 pre-dispersion was 600 g) to obtain a mixture, which was then pre-mixed in a planetary mixer. The mixed nickel paste was then crushed and dispersed in a three-roll mill, and the dispersed nickel paste was filtered under pressure, with the pore size of the filter element being 15 μm and the pressure being 10 kPa. Finally, a modified nickel paste for MLCC was obtained. The rotation speed of the dispersion disc in the planetary mixer is 100 r / min, the rotation speed of the central shaft disc is 200 r / min, the vacuum pressure is 10 kPa, and the mixing time is 60 min. When dispersing the nickel paste, the process parameters of the three-roll mill were as follows: (1) the rotational speed ratio of the three rolls was 1:3:9, and the rotational speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 100 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure of the scraper and rolls was 2 bar; and (5) the number of grinding operations was 5.

[0084] Example 27 The modified nickel paste for MLCC was prepared according to the following steps.

[0085] In the nano-BaTiO3 pre-dispersion step, 750 g of nano-BaTiO3 powder with a particle size of 50 nm was mixed with 240 g of diluent prepared in Preparation Example A and 10 g of dispersant, and the mixture was stirred in a mixer for 30 minutes to achieve uniform mixing. The mixture was then ground and dispersed in a three-roll mill to obtain nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were as follows: (1) the rotation speed ratio of the three rolls was 1:3:9, and the rotation speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 50 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 6 bar, and the pressure between the scraper and the rolls was 5 bar; and (5) the number of grinding times was 5. In the nickel paste preparation step, the above-mentioned BaTiO3 pre-dispersion, the adhesive prepared in Preparation Example 1, the dispersant DISPERBYK-108, the diluent prepared in Preparation Example A, and the nickel powder having a particle size of 300 nm prepared in Preparation Example b were mixed in a mass ratio of 20:20:1:20:50 (the mass of the BaTiO3 pre-dispersion was 600 g) to obtain a mixture, which was then pre-mixed in a planetary mixer. The mixed nickel paste was then crushed and dispersed in a three-roll mill, and the dispersed nickel paste was filtered under pressure, with the pore size of the filter element being 15 μm and the pressure being 10 kPa. Finally, a modified nickel paste for MLCC was obtained. The rotation speed of the dispersion disc in the planetary mixer is 100 r / min, the rotation speed of the central shaft disc is 200 r / min, the vacuum pressure is 10 kPa, and the mixing time is 60 min. When dispersing the nickel paste, the process parameters of the three-roll mill were as follows: (1) the rotational speed ratio of the three rolls was 1:3:9, and the rotational speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 100 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure of the scraper and rolls was 2 bar; and (5) the number of grinding operations was 5.

[0086] Example 28 The modified nickel paste for MLCC was prepared according to the following steps.

[0087] In the nano-BaTiO3 pre-dispersion step, 750 g of nano-BaTiO3 powder with a particle size of 40 nm was mixed with 240 g of diluent prepared in Preparation Example A and 10 g of dispersant, and the mixture was stirred in a mixer for 30 minutes to achieve uniform mixing. The mixture was then ground and dispersed in a three-roll mill to obtain nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were as follows: (1) the rotation speed ratio of the three rolls was 1:3:9, and the rotation speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 50 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure between the scraper and the rolls was 1 bar; and (5) the number of grinding times was 5. In the nickel paste preparation step, the above-mentioned BaTiO3 pre-dispersion, the adhesive prepared in Preparation Example 1, the dispersant DISPERBYK-108, the diluent prepared in Preparation Example A, and the nickel powder having a particle size of 200 nm prepared in Preparation Example b were mixed in a mass ratio of 20:20:1:20:50 (the mass of the BaTiO3 pre-dispersion was 600 g) to obtain a mixture, which was then pre-mixed in a planetary mixer. The mixed nickel paste was then crushed and dispersed in a three-roll mill, and the dispersed nickel paste was filtered under pressure, with the pore size of the filter element being 15 μm and the pressure being 10 kPa. Finally, a modified nickel paste for MLCC was obtained. The rotation speed of the dispersion disc in the planetary mixer is 100 r / min, the rotation speed of the central shaft disc is 200 r / min, the vacuum pressure is 10 kPa, and the mixing time is 60 min. When dispersing the nickel paste, the process parameters of the three-roll mill were as follows: (1) the rotational speed ratio of the three rolls was 1:3:9, and the rotational speeds of the three rolls were 50 r / min, 150 r / min, and 450 r / min, respectively; (2) the roll warp was designed to be 100 μm; (3) the temperature of the three rolls was 25°C; (4) the oil pressure of the three rolls was 3 bar, and the pressure of the scraper and rolls was 2 bar; and (5) the number of grinding operations was 5.

[0088] Comparative Example Comparative Example 1 The modified nickel paste for MLCC was prepared according to the following steps.

[0089] 0.74 kg of nano BaTiO3 powder with a particle size of 10 nm, 1 kg of adhesive produced in Production Example 1, 0.02 kg of dispersant, 1.25 kg of diluent produced in Production Example A, and 3 kg of nickel powder produced in Production Example a were mixed to obtain a mixture, which was then placed in a planetary mixer for pre-mixing. The mixed nickel paste was then placed in a three-roll mill to disperse it, and the dispersed nickel paste was filtered under pressure to obtain a modified nickel paste for MLCC. The filter element specifications, planetary mixer process parameters, and three-roll mill process parameters were all the same as in Example 1.

[0090] Comparative Example 2 The modified nickel paste for MLCC was prepared according to the following steps.

[0091] In the nano-BaTiO3 pre-dispersion step, 6 kg of nano-BaTiO3 powder with a particle size of 10 nm was mixed with 2 kg of diluent prepared in Preparation Example A and 0.1 kg of dispersant, and after uniform mixing, the mixture was dispersed in a three-roll mill to obtain a nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were the same as those in Example 1. In the nickel paste preparation step, 0.55 kg of BaTiO3 pre-dispersion, 1.09 kg of adhesive prepared in Preparation Example 1, 0.01 kg of dispersant, 1.09 kg of diluent prepared in Preparation Example A, and 3.27 kg of nickel powder prepared in Preparation Example a were mixed to obtain a mixture, which was then placed in a planetary mixer for pre-mixing. The mixed nickel paste was then placed in a three-roll mill for dispersion, and the dispersed nickel paste was filtered under pressure to obtain a modified nickel paste for MLCC. The filter element specifications, planetary mixer process parameters, and three-roll mill process parameters were all the same as in Example 1.

[0092] Comparative Example 3 The modified nickel paste for MLCC was prepared according to the following steps.

[0093] In the nano-BaTiO3 pre-dispersion step, 6 kg of nano-BaTiO3 powder with a particle size of 10 nm was mixed with 2 kg of diluent prepared in Preparation Example A and 0.1 kg of dispersant, and after uniform mixing, the mixture was dispersed in a three-roll mill to obtain a nano-BaTiO3 pre-dispersion. The process parameters of the three-roll mill were the same as those in Example 1. In the nickel paste preparation step, 2 kg of BaTiO3 pre-dispersion, 0.8 kg of adhesive prepared in Preparation Example 1, 0.01 kg of dispersant, 0.8 kg of diluent prepared in Preparation Example A, and 2.4 kg of nickel powder prepared in Preparation Example a were mixed to obtain a mixture, which was then placed in a planetary mixer for pre-mixing. The mixed nickel paste was then placed in a three-roll mill for dispersion, and the dispersed nickel paste was filtered under pressure to obtain a modified nickel paste for MLCC. The filter element specifications, planetary mixer process parameters, and three-roll mill process parameters were all the same as in Example 1.

[0094] Detection Method In the dispersibility test, the surface roughness was measured using a surface roughness tester. The modified nickel pastes for MLCC manufactured in Examples 1 to 28 and Comparative Examples 1 to 3 were used to screen print a regular pattern of length x width = 10 mm x 10 mm on a glass substrate, and then dried in a bag-type drying oven. The surface roughness Ra and Rt were then measured to characterize the dispersibility of the modified nickel paste. The lower the roughness, the better the dispersibility. In the electrical performance test, the modified nickel pastes for MLCCs manufactured in Examples 1 to 28 and Comparative Examples 1 to 3 were used. First, the thickness of the ceramic powder casting film was designed based on the dimensional specifications of the MLCC and the K value of the selected ceramic powder. MLCCs were then manufactured through the following processes: ceramic powder casting film (manufacturing ceramic paste and casting ceramic film) - manufacturing internal electrodes (screen printing of nickel paste and underlayer) - manufacturing capacitor chips (lamination and cutting separation) - sintered ceramic formation (discharging adhesive, sintering and chamfering) - manufacturing external electrodes (terminal formation, baking and electroplating). Using a four-parameter testing machine, performance tests were conducted on the above-mentioned manufactured MLCCs (each example / comparison example was considered as one set, and each set corresponded to 50 MLCCs). The capacitance, loss, withstand voltage and TCC at 200°C of the MLCCs were tested, where TCC = (C(200°C)-C(25°C)) / C(25°C) x 100%, and the smaller the absolute value of TCC, the better the high temperature resistance performance of the MLCC (C(200°C) and C(25°C) represent the capacitance of the MLCC at different temperatures). The test voltage was 1V and the frequency was 1kHz. The specific measurement results are shown in Table 4 below.

[0095] The capacitance value, loss, and TCC at 200°C are average values ​​of 50 MLCCs, and the withstand voltage is a range value.

[0096] In the accelerated aging test, the MLCCs manufactured as described above were placed in an aging tester (each example / comparative example was considered as one set, and each set corresponded to 100 MLCCs), and the capacitance (C), loss (DF), and insulation resistance (IR) of the MLCCs were tested before and after they were placed in the aging tester under conditions of 8Ur, 150°C, and 8 hours. If |ΔC / C|≦20%, DF≦2 times the initial value, and IR≧2000mΩ were satisfied, the product was deemed to be non-defective. The pass rate of each set was tested to characterize the adhesion performance of the modified nickel paste and the ceramic coating layer, and the effect of the diluent on the ceramic coating layer (pass rate = number of non-defective products / 100).

[0097] [Table 4]

[0098] As can be seen from Table 4 (Performance Test), the nickel paste produced in the Examples of the present application had Ra≦0.083 μm and Rt≦0.692 μm, which indicates that the nickel paste produced in the Examples of the present application had excellent dispersion performance and that the nano-BaTiO powder was well dispersed in the nickel paste. The MLCC produced using the nickel paste produced in the Examples of the present application had a capacitance value of ≧0.95 μF, a loss of ≦2.9%, a withstand voltage of ≧345 V, an absolute value of TCC at 200°C of ≦13.1, and a pass rate in the accelerated aging test of ≧85%, which indicates that the finished MLCC has good usage performance.

[0099] As can be seen from Table 4 combining Example 1 and Comparative Example 1, the roughness of the nickel paste in Example 1 is much smaller than that of Comparative Example 1, and the performance of the finished MLCC product produced from the nickel paste of Example 1 is also superior to that of Comparative Example 1. This shows that in Example 1, the nano-BaTiO3 powder is pre-dispersed with a dispersant to obtain a uniformly dispersed nano-BaTiO3 pre-dispersed product, and the nano-BaTiO3 pre-dispersed product is then mixed and dispersed with nickel powder and other raw materials in a specific ratio to obtain a uniformly dispersed nickel paste, thereby solving the problem of the nano-BaTiO3 powder not being uniformly dispersed in the nickel paste for MLCCs and improving the performance of the finished MLCC product.

[0100] As can be seen by combining Example 1 and Comparative Examples 2-3 and referring to Table 4, the roughness of the nickel paste in Example 1 is much smaller than that of Comparative Examples 2-3, and the performance of the finished MLCC product manufactured from the nickel paste of Example 1 is also superior to that of Comparative Examples 2-3. This may be because the mass ratios of the BaTiO3 pre-dispersion, adhesive, dispersant, diluent, and nickel powder in Comparative Examples 2-3 are not within the ranges of the present application. After multiple experiments, the inventors have found that by controlling the mass ratios of the above raw materials, the raw materials can be uniformly dispersed in the nickel paste, improving the usage performance of the finished MLCC product.

[0101] As can be seen by combining Example 1 and Examples 11 to 18 and referring to Table 4, the pass rates of the MLCC finished products manufactured in Examples 1 and 11 were much higher than those of Examples 12 to 18. This may be because the diluent selected in Examples 1 and 11 was a mixture of terpineol, isobornyl acetate, and butyl acetate in a specific mass ratio. The inventors discovered through multiple experiments that selecting the above diluent reduces damage to the ceramic coating layer, thereby improving the aging resistance of the MLCC finished products.

[0102] As can be seen by combining Examples 1 to 5 and Example 22 and referring to Table 4, the pass rates of the finished MLCC products manufactured in Examples 1 to 3 were much higher than those of Examples 4 to 5 and Example 22. This may be because the adhesive selected in Examples 1 to 3 was different from that in Examples 4 to 5 and Example 22. In Examples 1 to 3, ethyl cellulose was grafted onto polyvinyl butyral molecules using a terminal epoxy group hyperbranched polyester as a bridge to obtain an adhesive containing multiple active groups. This adhesive was then added to the nickel paste, with some of the active groups in the adhesive crosslinking with each other to firmly bond the components, and some of the active groups bonding to the hydroxyl groups in the ceramic coating layer to provide good adhesion between the nickel paste and the ceramic coating layer, thereby improving the performance of the finished MLCC.

[0103] The adhesive in Example 4 is pure polyvinyl butyral, the adhesive in Example 5 is pure ethyl cellulose, and the adhesive in Example 22 is a simple blend of polyvinyl butyral and ethyl cellulose. The adhesive strength of these three types of adhesives to the ceramic coating layer is weaker than that of the adhesives used in Examples 1 to 3.

[0104] As can be seen by combining Example 1 and Examples 19 to 21 and referring to Table 4, the withstand voltage values ​​of the finished MLCC products manufactured in Examples 19 and 21 are much higher than those of Examples 1 and 20, and the absolute TCC values ​​at 200°C of the finished MLCC products manufactured in Examples 19 and 21 are lower than those of Examples 1 and 20. This may be because the nickel powder selected in Examples 19 and 21 is doped with sulfur and other metals and has better withstand voltage performance and high temperature resistance performance than the nickel powder selected in Examples 1 and 20, and using this nickel powder in the manufacture of MLCCs can fundamentally improve the withstand voltage performance and high temperature resistance performance of the MLCC.

[0105] The specific examples are merely illustrative of the present application and do not limit the present application. After reading this specification, a person skilled in the art may make modifications to the present examples as necessary without making any creative contribution thereto, but such modifications will be protected by patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for producing a modified nickel paste for MLCC (multilayer ceramic chip capacitor), comprising: Nano BaTiO ３ The powder, diluent, and dispersant were uniformly mixed and dispersed in a mass ratio of (60-90):(20-30):1 to obtain nano BaTiO ３ Obtaining the pre-dispersion nano-BaTiO ３ a pre-dispersion step; The nano BaTiO ３ and a nickel paste preparation step of mixing, dispersing, dispersing agent, diluent, and nickel powder in a mass ratio of 10:(10-15):(0.1-1):(10-15):(25-60) to obtain a modified nickel paste for MLCC; The adhesive a step of preparing an epoxy-terminated hyperbranched polyester by reacting a hydroxyl-terminated hyperbranched polyester with epichlorohydrin in a mass ratio of (10-20):1 to obtain an epoxy-terminated hyperbranched polyester; a modified polyvinyl butyral preparation step of reacting the epoxy-terminated hyperbranched polyester with polyvinyl butyral in a mass ratio of (10-25):1 to obtain modified polyvinyl butyral; and an adhesive production step of reacting modified polyvinyl butyral and ethyl cellulose in a mass ratio of (2 to 10:1) to obtain an adhesive.

2. The nano BaTiO ３ 2. The method according to claim 1, wherein the mass ratio of the pre-dispersion to the nickel powder is 10:(50-60).

3. The nano BaTiO ３ 2. The method according to claim 1, wherein the particle size of the powder is 10 to 200 nm.

4. 2. The method according to claim 1, wherein the diluent is one or more of terpineol, isobornyl acetate, isophorone, and butyl acetate.

5. 5. The method according to claim 4, wherein the diluent is a mixture of terpineol, isobornyl acetate, and butyl acetate in a mass ratio of (0.2-1):(0.5-1.5):

1.

6. 2. The manufacturing method according to claim 1, wherein the nickel powder is synthesized by a chemical method, and raw materials for the nickel powder include nickel sulfate and other metal salts, and the other metal salts are one or more of chromium sulfate, copper sulfate, and silver sulfate.

7. 2. The manufacturing method according to claim 1, wherein the nickel powder is synthesized by a physical vapor deposition method, and raw materials for the nickel powder include a nickel target, sulfur powder, and another metal target, and the other metal target is one or more of a chromium target, a copper target, and a silver target.

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