Lead-free glass powder, silver-palladium inner electrode paste, preparation method of silver-palladium inner electrode paste and silver-palladium inner electrode

Abstract

The invention provides lead-free glass powder, silver-palladium inner electrode paste, a preparation method of the silver-palladium inner electrode paste and a silver-palladium inner electrode, and belongs to the field of electronic components. The invention provides lead-free glass powder, which comprises the following components in percentage by mass: 22 to 40 percent of CaO; 18 to 25 percent of Bi2O3; 17 to 28% of B2O3; 7 to 26% of SiO2; 2 to 4 percent of Al2O3; 0-5% of CuO; the content of the ZnO and the content of the CuO are not 0 at the same time. CaO, Bi2O3, B2O3, SiO2 and Al2O3 serve as main components of the lead-free glass powder, the glass expansion coefficient of the glass powder can be regulated and controlled by adding other oxide ZnO, CuO and other components, connection between an electrode layer and a dielectric layer can be formed by adding the glass powder after the slurry is sintered, and too fast shrinkage of the slurry in the sintering process is inhibited.

Description

Technical Field

[0001] The present invention relates to the field of electronic components, and particularly relates to a lead-free glass powder, a silver-palladium inner electrode paste and a preparation method thereof, and a silver-palladium inner electrode. Background Art

[0002] Electronic paste is the material basis and technological forerunner of the development of electronic components, and its quality directly affects the reliability and stability of the circuit.

[0003] Silver-palladium paste is a mixed material formed by precious metals, glass powder and organic carriers. Silver has excellent anti-migration ability, excellent electrical properties, stable performance, and special advantages such as adapting to sintering in an atmospheric environment. It is a raw material for electronic components such as semiconductor discrete devices, integrated circuits, thick-film hybrid circuits, chip multi-layer ceramic capacitors (MLCCs), and chip inductors.

[0004] Silver-palladium paste generally includes glass powder, organic carrier and solvent. Currently, the existing silver-palladium paste has problems of low densification and low adhesion strength of the porcelain body after sintering. Summary of the Invention

[0005] The present invention provides a lead-free glass powder, a silver-palladium inner electrode paste and a preparation method thereof, and a silver-palladium inner electrode. The silver-palladium paste prepared by using the lead-free glass powder of the present invention has high densification and high adhesion strength of the porcelain body after sintering.

[0006] The present invention provides a lead-free glass powder which, by mass fraction, comprises the following components:

[0007]

[0008] And ZnO and CuO are not both 0 at the same time.

[0009] The present invention also provides a silver-palladium inner electrode paste which, by mass fraction, comprises the following components:

[0010] Silver-palladium powder: 70-85%;

[0011] Lead-free glass powder: 0-5%; the mass fraction of the lead-free glass powder is not 0;

[0012] The lead-free glass powder is the lead-free glass powder described in claim 1;

[0013] Organic carrier: 10-25%.

[0014] Preferably, the mass content of Pd in the silver-palladium powder is 5-30%.

[0015] Preferably, the maximum particle size of the silver-palladium powder < 5 μm, and the tapped density is 1.5-2.5 g / cm 3, with a specific surface area of 2.5 to 3.5 m 2 / g.

[0016] Preferably, the method for preparing the silver-palladium powder includes the following steps:

[0017] A salt solution containing silver nitrate and palladium nitrate and a solution of a reducing agent are simultaneously added to a solution of a dispersant for a reduction reaction to obtain the silver-palladium powder.

[0018] Preferably, by mass fraction, the organic carrier includes:

[0019] Resin 5 to 30%;

[0020] Organic solvent 60 to 90%;

[0021] Auxiliary agent 2 to 10%.

[0022] Preferably, the resin includes one or more of ethyl cellulose, alkyd resin, and polyvinyl butyral.

[0023] Preferably, the organic solvent includes one or more of terpineol, turpentine, butyl carbitol, butyl carbitol acetate, and ethylene glycol;

[0024] The auxiliary agent includes one or more of castor oil, lecithin, span-85, and rosin.

[0025] The present invention also provides a method for preparing the silver-palladium inner electrode paste described in the above technical solution, including the following steps:

[0026] Part of the organic carrier is mixed with lead-free glass powder and then ground, and then the ground paste is mixed with the remaining organic carrier, and then the obtained paste is subjected to reduced-pressure defoaming to obtain the silver-palladium inner electrode paste.

[0027] The present invention also provides a silver-palladium inner electrode, which is obtained by sintering the silver-palladium inner electrode paste described in the above technical solution or the silver-palladium inner electrode paste prepared by the preparation method described in the above technical solution after being coated on ceramics;

[0028] The temperature of the sintering is the glass softening temperature of the lead-free glass powder ±20°C.

[0029] In the lead-free glass powder provided by the present invention, CaO, Bi2O3, B2O3, SiO2, and Al2O3 are the main components of the lead-free glass powder. The addition of other oxide components such as ZnO and CuO can regulate the glass expansion coefficient of the glass powder. After the slurry is sintered, the addition of the glass powder can form a connection between the electrode layer and the dielectric layer, inhibit the excessive shrinkage of the slurry during the firing process, that is, adjust the matching performance of the shrinkage rates of the slurry and the dielectric material during the firing process, avoid the cracking problem between the electrode layers caused by the action of the internal stress between the layers, and improve the bonding strength and current-carrying capacity.

[0030] Furthermore, the silver-palladium alloy powder prepared by the present invention has higher anti-migration ability and smaller shrinkage rate, which can further improve the densification of the slurry after sintering.

[0031] Furthermore, the organic carrier provided by the present invention has high wettability on the particle surface, and the low resin content can effectively solve the problem of large amount of binder burnout, meeting the usage requirements of different construction processes.

[0032] The slurry preparation method provided by the present invention helps to improve the dispersion efficiency, reduce the damage to the powder material, and the slurry has good particle dispersion and high flatness. Description of the Drawings

[0033] Figure 1 It is the SEM image of the silver-palladium internal electrode slurry sintered in Example 1;

[0034] Figure 2 It is the SEM image of the silver-palladium internal electrode slurry sintered in Example 2;

[0035] Figure 3 It is the SEM image of the silver-palladium internal electrode slurry sintered in Example 3;

[0036] Figure 4 It is the SEM image of the silver-palladium internal electrode slurry sintered in Example 4;

[0037] Figure 5 It is the SEM image of the silver-palladium internal electrode slurry sintered in Example 5;

[0038] Figure 6 It is the SEM image of the silver-palladium internal electrode slurry sintered in Comparative Example 1;

[0039] Figure 7 It is the SEM image of the silver-palladium internal electrode slurry sintered in Comparative Example 2;

[0040] Figure 8 It is the SEM image of the silver-palladium internal electrode slurry sintered in Comparative Example 3. Detailed Embodiments

[0041] The present invention provides a lead-free glass powder, which comprises the following components by mass fraction:

[0042]

[0043] and ZnO and CuO are not both 0.

[0044] By mass fraction, the components of the lead-free glass powder provided by the present invention include 22-40% of CaO. In specific embodiments of the present invention, the mass fraction of CaO can be 22%, 25%, 30%, 35% or 40%;

[0045] By mass fraction, the components of the lead-free glass powder provided by the present invention include 18-25% of Bi2O3. In specific embodiments of the present invention, the mass fraction of Bi2O3 can be 22%, 25%, 30%, 35% or 40%;

[0046] By mass fraction, the components of the lead-free glass powder provided by the present invention include 17-28% of B2O3. In specific embodiments of the present invention, the mass fraction of B2O3 can be 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27% or 28%;

[0047] By mass fraction, the components of the lead-free glass powder provided by the present invention include 7-26% of SiO2. In specific embodiments of the present invention, the mass fraction of SiO2 can be 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25% or 26%;

[0048] By mass fraction, the components of the lead-free glass powder provided by the present invention include 2-4% of Al2O3. In specific embodiments of the present invention, the mass fraction of Al2O3 can be 2%, 2.5%, 3%, 3.5% or 4%;

[0049] By mass fraction, the components of the lead-free glass powder provided by the present invention include 0-5% of CuO. In specific embodiments of the present invention, the mass fraction of CuO can be 0, 1%, 2%, 3%, 4% or 5%;

[0050] By mass fraction, the components of the lead-free glass powder provided by the present invention include 0-3% of ZnO. In specific embodiments of the present invention, the mass fraction of ZnO can be 0%, 1%, 1.5%, 2%, 2.5% or 3%

[0051] The present invention also provides a silver-palladium inner electrode paste, which comprises the following components by mass fraction:

[0052] 70-85% of silver-palladium powder;

[0053] Lead-free glass powder: 0 to 5%; the mass fraction of the lead-free glass powder is not 0;

[0054] The lead-free glass powder is the lead-free glass powder described in claim 1;

[0055] Organic carrier: 10 to 25%.

[0056] By mass, the components of the silver-palladium inner electrode paste provided by the present invention include 70 to 85% of silver-palladium powder. In specific embodiments of the present invention, the mass fraction of the silver-palladium powder can be 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84% or 85%; the mass content of Pd in the silver-palladium powder is preferably 5 to 30%. In specific embodiments of the present invention, the mass content of Pd in the silver-palladium powder can be 5%, 10%, 15%, 20%, 25% or 30%.

[0057] In the present invention, the preparation method of the silver-palladium powder preferably includes the following steps:

[0058] A salt solution containing silver nitrate and palladium nitrate and a solution of a reducing agent are simultaneously added to a solution of a dispersant for a reduction reaction to obtain the silver-palladium powder.

[0059] In the present invention, the mass fraction of silver nitrate in the salt solution is preferably 0.9 to 1.5%. In specific embodiments of the present invention, the mass fraction of silver nitrate in the salt solution can be 0.9, 1, 1.1, 1.2, 1.3, 1.4 or 1.5%.

[0060] In the present invention, the volume ratio of water in the salt solution to water in the solution of the reducing agent is preferably 1:1, and the volume ratio of water in the salt solution to water in the solution of the dispersant is preferably 1:2.

[0061] In the present invention, the molar ratio of the reducing agent to the total molar amount of silver nitrate and palladium nitrate is preferably 2 to 5:1. In specific embodiments of the present invention, the molar ratio of the reducing agent to the total molar amount of silver nitrate and palladium nitrate can be 2:1, 3:1, 4:1 or 5:1. The reducing agent is preferably ascorbic acid;

[0062] The mass ratio of the dispersant to the total mass of silver nitrate and palladium nitrate is preferably 0.05 to 0.2:1. In specific embodiments of the present invention, the molar ratio of the dispersant to the total molar amount of silver nitrate and palladium nitrate can be 0.05:1:1, 0.1:1, 0.15:1 or 0.2:1; the dispersant is preferably one or more of polyvinylpyrrolidone, glycerol and polyethylene glycol 400.

[0063] The reduction reaction is preferably carried out under stirring, and the stirring speed is preferably 500 - 1000 rpm. In specific embodiments of the present invention, the stirring speed can be 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm or 1000 rpm. The present invention has no special limitation on the time of the reduction reaction, and the reaction can be stopped until the supernatant is clear.

[0064] After the reduction reaction is completed, the present invention preferably allows the obtained product to stand and perform solid-liquid separation, and then the obtained solid is washed, dried, ball-milled and dried again to obtain the silver-palladium alloy powder.

[0065] In the present invention, the drying temperature is preferably 65 - 75 °C, and the time is preferably 6 - 10 h. In specific embodiments of the present invention, the drying temperature can be 60 °C, 65 °C, 70 °C or 75 °C, and the time can be 6 h, 8 h, 9 h or 10 h.

[0066] The ball-milling is preferably carried out in an intelligent horizontal ball mill. The ball-to-material ratio during ball-milling is preferably 5:1, the time is preferably 6 - 8 h, and the ball-milling rate is preferably 75 - 125 r / min. In specific embodiments of the present invention, the time can be 6 h, 7 h or 8 h, and the rate can be 75 r / min, 80 r / min, 90 r / min, 100 r / min, 110 r / min, 120 r / min or 125 r / min.

[0067] By mass, the components of the silver-palladium inner electrode paste provided by the present invention include 0 - 5% of lead-free glass powder; the mass fraction of the lead-free glass powder is not 0. In specific embodiments of the present invention, the mass fraction in the lead-free glass powder can be 0.1%, 1%, 2%, 3%, 4% or 5%;

[0068] By mass, the components of the silver-palladium inner electrode paste provided by the present invention include 10 - 25% of an organic carrier. In specific embodiments of the present invention, the mass fraction of the organic carrier can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24% or 25%;

[0069] In the present invention, by mass fraction, the components of the organic carrier preferably include 5 - 30% of resin. In specific embodiments of the present invention, the mass fraction of the resin can be 5%, 10%, 15%, 20%, 25% or 30%; the resin preferably includes one or more of ethyl cellulose, alkyd resin and polyvinyl butyral.

[0070] By mass fraction, the components of the organic carrier preferably include 60-90% of an organic solvent. In specific embodiments of the present invention, the mass fraction of the organic solvent can be 60%, 65%, 70%, 75%, 80%, 85% or 90%; the organic solvent preferably includes one or more of terpineol, turpentine, butyl carbitol, butyl carbitol acetate and ethylene glycol.

[0071] By mass fraction, the components of the organic carrier preferably include 2-10% of an auxiliary agent. In specific embodiments of the present invention, the mass fraction of the auxiliary agent can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%; the auxiliary agent preferably includes one or more of castor oil, lecithin, span-85 and rosin.

[0072] In the present invention, the preparation method of the organic carrier preferably includes the following steps:

[0073] First mix the resin and the organic solvent, and then perform a second mixing with the auxiliary agent.

[0074] In the present invention, the first mixing is preferably carried out in a high-speed disperser, and the temperature of the first mixing is preferably not more than 70°C.

[0075] The present invention has no special limitation on the time of the first mixing, and it is only necessary to dissolve the resin in the organic solvent.

[0076] In the present invention, after the first mixing and before the second mixing, it preferably includes: cooling the mixture obtained from the first mixing to room temperature.

[0077] In the present invention, the second mixing is preferably carried out in a high-speed disperser, and the time of the second mixing is preferably 1-2 h.

[0078] The present invention also provides a preparation method of the silver-palladium inner electrode paste described in the above technical solution, including the following steps:

[0079] Mix a part of the organic carrier with the lead-free glass powder and then grind it, then mix the ground paste with the remaining organic carrier, and then perform vacuum defoaming on the obtained paste to obtain the silver-palladium inner electrode paste.

[0080] In the present invention, the part of the organic carrier is 80-90% of the total amount of the organic carrier.

[0081] The present invention has no special limitation on the grinding, and it is only necessary to grind the fineness of the ground paste to less than 10 μm.

[0082] The present invention also provides a silver-palladium inner electrode, which is obtained by coating the silver-palladium inner electrode paste described in the above technical solution or the silver-palladium inner electrode paste prepared by the preparation method described in the above technical solution on ceramics and then sintering;

[0083] The temperature of the sintering is the glass softening temperature of the lead-free glass powder.

[0084] In the present invention, the temperature of the sintering is preferably the glass softening temperature of the lead-free glass powder ±20°C, the heating rate for heating to the temperature of the sintering is preferably 10°C / min, and the heat preservation time is preferably 45 min.

[0085] The glass softening temperature matches the sintering temperature, and the solderability and solder resistance of the paste are increased: if the sintering temperature is much higher than the glass softening temperature, the glass powder will form a glass glaze on the surface of the paste, affecting the solderability.

[0086] The following will combine examples to elaborate in detail on the lead-free glass powder, silver-palladium inner electrode paste and its preparation method, and silver-palladium inner electrode provided by the present invention, but they cannot be construed as limiting the protection scope of the present invention.

[0087] Weigh a palladium nitrate solution (concentration: 0.1 g / mL) containing x g of palladium ions and y g of silver nitrate, and dissolve them in 1000 mL of deionized water at room temperature to fully dissolve and prepare a metal salt oxidant solution;

[0088] Slowly dissolve ascorbic acid in 1000 mL of deionized water under stirring to prepare a reducing agent solution, and the molar ratio of ascorbic acid to the amount of substance of palladium nitrate and silver nitrate is 2:1;

[0089] Slowly dissolve PVP in 2000 mL of deionized water under stirring to prepare a base solution, and the mass ratio of PVP to the total mass of palladium nitrate and silver nitrate is 0.1:1;

[0090] Slowly drop the metal salt oxidant solution and the reducing agent solvent into the base solution simultaneously under stirring at a stirring speed of 500 rmp. Stir until the supernatant becomes clear, let it settle naturally for 2 h, wash it with water at 50°C to obtain silver-palladium alloy particles; place the obtained silver-palladium powder in a vacuum drying oven, dry it at 65°C for 12 h, and use an intelligent horizontal ball mill to ball mill and dry the silver-palladium alloy powder, where the ball-to-material ratio is 5:1, the ball milling time is 8 h, and the ball milling rate is 75 r / min to finally obtain a silver-palladium powder product.

[0091] When x = 3 and y = 11, the prepared silver-palladium powder product is AgPd30;

[0092] When x = 1.5 and y = 13.4, the prepared silver-palladium powder product is AgPd15;

[0093] When x = 0.5 and y = 15, the prepared silver-palladium powder product is AgPd5.

[0094] Example 1

[0095] The composition of the lead-free glass powder is 40wt% CaO, 18wt% Bi2O3, 17wt% B2O3, 18wt% SiO2, 2wt% Al2O3, 5wt% CuO, and the glass softening point is 705°C.

[0096] Add 5wt% ethyl cellulose to a mixed solvent of 87wt% turpentine alcohol and butyl carbitol (where turpentine alcohol is 25wt% and butyl carbitol is 75wt%), stir with a high-speed disperser at a temperature not exceeding 70°C. After the resin is completely dissolved, cool to room temperature, and add a mixed auxiliary agent of 8wt% lecithin, Span-85 and rosin (where lecithin is 40wt%, Span-85 is 40wt%, and rosin is 20wt%), and mix with a high-speed disperser for 1 - 2h to obtain an organic carrier.

[0097] Weigh the raw materials according to the following mass percentages: 73wt% AgPd30 alloy powder, 2wt% lead-free glass powder, 25wt% organic carrier.

[0098] Pre-mix 80% of the total amount of the organic carrier with the lead-free glass powder into a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10μm, then mix in the remaining organic carrier, stir with a double planetary mixer, and finally carry out vacuum degassing to obtain a silver-palladium inner electrode slurry.

[0099] The sintering temperature of the slurry is 700°C, the heating rate is 10°C / min, and the holding time is 45min.

[0100] Figure 1 The SEM image after sintering of the silver-palladium inner electrode slurry prepared for Example 1 shows that the slurry has good densification after sintering and no obvious pores.

[0101] Example 2

[0102] The composition of the lead-free glass powder is 37wt% CaO, 25wt% Bi2O3, 20wt% B2O3, 7wt% SiO2, 4wt% Al2O3, 5wt% CuO, 2wt% ZnO, and the glass softening point is 610°C.

[0103] Add 6wt% ethyl cellulose and 15wt% alkyd resin to a mixed solvent of 48wt% terpineol and 26wt% ethylene glycol, stir with a high-speed disperser at a temperature not exceeding 70°C. After the resin is completely dissolved, cool to room temperature, and add 5wt% castor oil, and mix with a high-speed disperser for 1 - 2h to obtain an organic carrier.

[0104] Weigh the raw materials according to the following mass percentages: 75 wt% AgPd15 alloy powder, 1 wt% lead-free glass powder, and 24 wt% organic carrier.

[0105] Pre-mix 85% of the total amount of the organic carrier with the lead-free glass powder to form a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10 μm, then mix in the remaining organic carrier, and use a double planetary mixer to stir and finally degas under reduced pressure to obtain the silver-palladium inner electrode slurry.

[0106] The sintering temperature of the slurry is 650 °C, the heating rate is 10 °C / min, and the holding time is 45 min.

[0107] Figure 2 The SEM image after sintering of the silver-palladium inner electrode slurry prepared for Example 2 shows that the compactness of the slurry after sintering is relatively good.

[0108] Example 3

[0109] The composition of the lead-free glass powder is 22 wt% CaO, 25 wt% Bi2O3, 28 wt% B2O3, 20 wt% SiO2, 4 wt% Al2O3, 1 wt% CuO, and the glass softening point is 820 °C.

[0110] Add 8 wt% ethyl cellulose to a mixed solvent of 90 wt% turpentine and butyl carbitol (where turpentine is 75 wt% and butyl carbitol is 25 wt%), stir with a high-speed disperser at a temperature not exceeding 70 °C, and after the resin is completely dissolved, cool to room temperature, and add a mixed auxiliary agent of 2 wt% castor oil and lecithin (where castor oil is 50 wt% and lecithin is 50 wt%), and mix with a high-speed disperser for 1 - 2 h to obtain the organic carrier.

[0111] Weigh the raw materials according to the following mass percentages: 74 wt% AgPd5 alloy powder, 3 wt% lead-free glass powder, and 23 wt% organic carrier.

[0112] Pre-mix 90% of the total amount of the organic carrier with the lead-free glass powder to form a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10 μm, then mix in the remaining organic carrier, and use a double planetary mixer to stir and finally degas under reduced pressure to obtain the silver-palladium inner electrode slurry.

[0113] The sintering temperature of the slurry is 850 °C, the heating rate is 10 °C / min, and the holding time is 45 min.

[0114] Figure 3 The SEM image after sintering of the silver-palladium inner electrode slurry prepared for Example 3 shows that the compactness of the slurry after sintering is relatively good.

[0115] Example 4

[0116] The composition of the lead-free glass powder is 25wt% CaO, 20wt% Bi2O3, 22wt% B2O3, 26wt% SiO2, 4wt% Al2O3, 1wt% CuO, 2wt% ZnO, and the glass softening point is 870 °C.

[0117] Add a mixed resin of 16wt% polyvinyl butyral and alkyd resin (where polyvinyl butyral is 90wt% and alkyd resin is 10wt%) to a mixed solvent of 81wt% terpineol, ethylene glycol, and butyl carbitol acetate (where terpineol is 40wt%, ethylene glycol is 40wt%, and butyl carbitol acetate is 20wt%), stir with a high-speed disperser at a temperature not exceeding 70 °C. After the resin is completely dissolved, cool to room temperature, and add a mixed auxiliary agent of 3wt% castor oil and span-85 (where castor oil is 60wt% and span-85 is 40wt%), and mix with a high-speed disperser for 1 - 2 hours to obtain an organic carrier.

[0118] Weigh the raw materials according to the following mass percentages: 78wt% AgPd30 alloy powder, 2wt% lead-free glass powder, and 20wt% organic carrier.

[0119] Pre-mix 90% of the total amount of the organic carrier with the lead-free glass powder into a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10μm, then mix in the remaining organic carrier, stir with a double planetary mixer, and finally carry out vacuum degassing to obtain the silver-palladium inner electrode slurry.

[0120] The sintering temperature of the slurry is 900 °C, the heating rate is 10 °C / min, and the holding time is 45 minutes.

[0121] Figure 4 SEM image of the silver-palladium inner electrode slurry sintered in Example 4. It can be seen that the density after sintering of the slurry is relatively good.

[0122] Example 5

[0123] The composition of the lead-free glass powder is 25wt% CaO, 20wt% Bi2O3, 22wt% B2O3, 26wt% SiO2, 4wt% Al2O3, 3wt% ZnO, and the glass softening point is 600 °C.

[0124] Add 5wt% ethyl cellulose to a mixed solvent of 87wt% terpineol and butyl carbitol (where terpineol is 25wt% and butyl carbitol is 75wt%), stir with a high-speed disperser at a temperature not exceeding 70 °C. After the resin is completely dissolved, cool to room temperature, and add a mixed auxiliary agent of 8wt% lecithin, span-85, and rosin (where lecithin is 40wt%, span-85 is 40wt%, and rosin is 20wt%), and mix with a high-speed disperser for 1 - 2 hours to obtain an organic carrier.

[0125] Weigh the raw materials according to the following mass percentages: 73 wt% AgPd30 alloy powder, 2 wt% lead-free glass powder, and 25 wt% organic carrier.

[0126] Pre-mix 80% of the total amount of the organic carrier with the lead-free glass powder to form a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10 μm, then mix in the remaining organic carrier, stir using a double planetary mixer, and finally perform vacuum defoaming to obtain the silver-palladium inner electrode slurry.

[0127] The sintering temperature of the slurry is 650 °C, the heating rate is 10 °C / min, and the holding time is 45 min.

[0128] Figure 5 The SEM image after sintering of the silver-palladium inner electrode slurry prepared in Example 5 is shown. It can be seen that the compactness of the slurry after sintering is relatively good.

[0129] Comparative Example 1

[0130] The composition of the lead-free glass powder is 10 wt% CaO, 40 wt% Bi2O3, 10 wt% B2O3, 15 wt% SiO2, and 25 wt% Al2O3, and the glass softening point is 800 °C.

[0131] Add 8 wt% ethyl cellulose to a mixed solvent of 90 wt% turpentine and butyl carbitol (where turpentine is 75 wt% and butyl carbitol is 25 wt%), stir using a high-speed disperser at a temperature not exceeding 70 °C, and after the resin is completely dissolved, cool to room temperature. Add a mixed auxiliary agent of 2 wt% castor oil and lecithin (where castor oil is 50 wt% and lecithin is 50 wt%), and mix using a high-speed disperser for 1 - 2 h to obtain the organic carrier.

[0132] Weigh the raw materials according to the following mass percentages: 75 wt% AgPd5 alloy powder, 2 wt% lead-free glass powder, and 23 wt% organic carrier.

[0133] Pre-mix 50% of the total amount of the organic carrier with the lead-free glass powder to form a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10 μm, then mix in the remaining organic carrier, stir using a double planetary mixer, and finally perform vacuum defoaming to obtain the silver-palladium inner electrode slurry.

[0134] The sintering temperature of the slurry is 800 °C, the heating rate is 10 °C / min, and the holding time is 45 min.

[0135] Figure 6 The SEM image after sintering of the silver-palladium inner electrode slurry prepared in Comparative Example 1 is shown. It can be seen that there are many pores and the compactness is poor after sintering of the slurry.

[0136] Comparative Example 2

[0137] The composition of the lead-free glass powder is 4 wt% CaO, 65 wt% Bi2O3, 10 wt% B2O3, 15 wt% SiO2, 6 wt% Al2O3, and the glass softening point is 650 °C.

[0138] Add 9 wt% ethyl cellulose to 86 wt% terpineol solvent, stir with a high-speed disperser at a temperature not exceeding 70 °C. After the resin is completely dissolved, cool it to room temperature, add 5 wt% castor oil, and mix with a high-speed disperser for 1 - 2 h to obtain an organic carrier.

[0139] Weigh the raw materials according to the following mass percentages: 72.5 wt% AgPd5 alloy powder, 5 wt% lead-free glass powder, 22.5 wt% organic carrier

[0140] Pre-mix 50% of the total amount of the organic carrier with the lead-free glass powder into a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10 μm, then mix in the remaining organic carrier, stir with a double planetary mixer, and finally carry out vacuum degassing to obtain the silver-palladium inner electrode slurry.

[0141] The sintering temperature of the slurry is 650 °C, the heating rate is 10 °C / min, and the holding time is 45 min.

[0142] Figure 7 The SEM image after sintering of the silver-palladium inner electrode slurry prepared for Comparative Example 2 shows that there are many pores and poor densification after sintering of the slurry.

[0143] Comparative Example 3

[0144] The composition of the lead-containing glass powder is 10 wt% CaO, 50 wt% PbO, 15 wt% B2O3, 15 wt% SiO2, 10 wt% Al2O3, and the glass softening point is 850 °C.

[0145] Add 8 wt% ethyl cellulose to a mixed solvent of 90 wt% turpentine and butyl carbitol (where turpentine is 75 wt% and butyl carbitol is 25 wt%), stir with a high-speed disperser at a temperature not exceeding 70 °C. After the resin is completely dissolved, cool it to room temperature, add 2 wt% of an additive of castor oil and lecithin (where castor oil is 50 wt% and lecithin is 50 wt%), and mix with a high-speed disperser for 1 - 2 h to obtain an organic carrier.

[0146] Weigh the raw materials according to the following mass percentages: 75 wt% AgPd5 alloy powder, 2 wt% lead-free glass powder, 23 wt% organic carrier.

[0147] Pre-mix 50% of the total amount of the organic carrier with the lead-free glass powder into a slurry, then add all the silver-palladium alloy powder, grind until the fineness of the slurry is less than 10 μm, then mix in the remaining organic carrier, stir with a double planetary mixer, and finally carry out vacuum degassing to obtain the silver-palladium inner electrode slurry.

[0148] The sintering temperature of the paste is 850 °C, the heating rate is 10 °C / min, and the holding time is 45 min.

[0149] Figure 8 The SEM image of the silver-palladium internal electrode paste prepared in Comparative Example 3 after sintering shows that there are many pores and poor compactness after sintering of the paste.

[0150] Performance Test

[0151] The silver-palladium internal electrode paste prepared in the above examples was subjected to performance tests, and the specific test methods are as follows.

[0152] (1) Electrical performance test

[0153] Test the resistance of the 0.6 mm×1 m serpentine line after curing, and use a Fluke17B + Multimeter and film thickness gauge to test the resistance and film thickness of the conductive line with a line width of 0.6 mm. The resistivity of the paste is obtained through the resistivity calculation formula, and the sheet resistance is further calculated.

[0154] (1) Solderability test and solder resistance test

[0155] Carry out solderability test and solder resistance test according to GB / T 17473.7 (it is excellent when the solder acceptance area of the conductive film of the substrate printed pattern is greater than or equal to 9 / 10 of the area).

[0156] (2) Peel adhesion test

[0157] Carry out adhesion test according to the standard GB / T17473.4-2008 "Test Method for Adhesion of Precious Metal Pastes for Microelectronic Technology".

[0158] The performance test results of the electrode materials prepared in the above Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1.

[0159] Table 1 Performance test results of the electrode materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3

[0160]

[0161] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A lead-free glass powder, characterized in that: In terms of mass fraction, it includes the following components: Furthermore, the ZnO and CuO are not 0 at the same time.

2. A silver-palladium internal electrode slurry, characterized in that: In terms of mass fraction, it includes the following components: Silver palladium powder 70-85%; Lead-free glass powder 0-5%; the mass fraction of the lead-free glass powder is not 0; The lead-free glass powder is the lead-free glass powder according to claim 1; Organic carrier 10-25%.

3. The silver-palladium internal electrode slurry according to claim 2, characterized in that: The mass content of Pd in ​​the silver palladium powder is 5-30%.

4. The silver-palladium internal electrode slurry according to claim 2, characterized in that: The maximum particle size of the silver palladium powder is less than 5 μm, and the tap density is 1.5 to 2.5 g / cm 3 , with a specific surface area of ​​2.5 to 3.5 m 2 / g.

5. The silver-palladium internal electrode slurry according to claim 2, 3 or 4, characterized in that: The preparation method of the silver-palladium powder comprises the following steps: The salt solution containing silver nitrate and palladium nitrate and the solution of the reducing agent are simultaneously added into the solution of the dispersant to carry out a reduction reaction, thereby obtaining the silver palladium powder.

6. The silver-palladium internal electrode slurry according to claim 2, characterized in that: In terms of mass fraction, the organic carrier comprises: Resin 5-30%; Organic solvent 60-90%; Additives 2-10%.

7. The silver-palladium internal electrode slurry according to claim 6, characterized in that: The resin includes one or more of ethyl cellulose, alkyd resin and polyvinyl butyral.

8. The silver-palladium internal electrode slurry according to claim 6, characterized in that: The organic solvent includes one or more of terpineol, turpentine, butyl carbitol, butyl carbitol acetate and ethylene glycol; The auxiliary agent includes one or more of castor oil, lecithin, Span-85 and rosin.

9. The method for preparing the silver-palladium internal electrode slurry according to any one of claims 2 to 8, characterized in that: The following steps are involved: A part of the organic carrier is mixed with the lead-free glass powder and then ground. Then, the ground slurry is mixed with the remaining organic carrier. Then, the obtained slurry is decompressed and degassed to obtain the silver-palladium internal electrode slurry.

10. A silver-palladium inner electrode, characterized in that: The silver-palladium internal electrode slurry according to any one of claims 2 to 8 or the silver-palladium internal electrode slurry prepared by the preparation method according to claim 9 is coated on ceramic and then sintered; The sintering temperature is ±20° C. of the glass softening temperature of the lead-free glass powder.

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