A high-adhesion 5G ceramic filter electrode silver paste and preparation method thereof

Abstract

The present invention discloses a 5G ceramic filter electrode silver paste with high adhesion and a preparation method thereof, wherein the mass percentage of the electrode silver paste is composed of: 75% to 85% of conductive filler, 1% to 3.5% of glass powder, 0.5% to 2% of inorganic additives, and 12% to 23% of organic carriers, wherein the glass powder is Si-Zn-B glass, which can effectively inhibit the diffusion erosion of glass relative to the functional ceramic body, while improving the interface bonding strength, reducing the glass content and improving the current carrying capacity of the sintered metal layer. After sintering, the silver paste of the present invention has high adhesion to the ceramic matrix, and the surface of the silver layer has high compactness and good conductivity, so that the filter has a higher quality factor.

Description

Technical Field

[0001] The present invention relates to the field of metallization process technology, and in particular to a high-adhesion 5G ceramic filter electrode silver paste and a preparation method thereof. Background Art

[0002] 5G's ultra-high speed, low latency, and massive access characteristics enable 5G networks to support many emerging technologies, greatly expanding from a single communication field to many application fields. Metal silver paste is widely used in 5G ceramic dielectric filters. Judging from the planned number of 5G base stations, the stock market for filter metal silver paste will reach tens of billions in the next 3-5 years. With the advent of the 5G era, ceramic filters have a broad market and prospects.

[0003] Ceramic filters achieve their functions by printing circuits on the surface of ceramics and welding them to circuit boards. Silver has the advantages of strong conductivity, thermal expansion coefficient close to that of ceramic blanks, good thermal stability, and the ability to directly weld metal on the silver layer. Although many institutions have invested in the research of slurries, there are relatively few that are suitable for 5G ceramic bases. There are many types of materials for the preparation of ceramic filters. The present invention is magnesium titanate ceramics, which require that the thermal expansion coefficient of the silver paste matches well, has good bonding force, and that the silver layer is dense after sintering, without problems such as peeling, shedding, and low adhesion of the silver layer. Therefore, it is very necessary to develop a 5G ceramic filter functional electrode silver paste with high conductivity, high adhesion, high surface density, and good solderability. Summary of the invention

[0004] The object of the present invention is to provide a 5G ceramic filter electrode silver paste with high adhesion, which is made of the following raw materials in percentage by mass:

[0005] Conductive filler 75%~85%;

[0006] Glass powder 1%~3.5%;

[0007] Inorganic additives 0.5% to 2%;

[0008] Organic carrier 12% to 23%;

[0009] The conductive filler is composed of three kinds of spherical silver powders with different particle sizes, wherein the weight ratios of fine-grained silver powder, medium-grained silver powder and coarse-grained silver powder are 25% to 45%, 40% to 60% and 15% to 25% respectively.

[0010] The glass powder comprises, by weight percentage, 5% to 10% SiO2, 35% to 50% ZnO, 20% to 30% B2O3, 1% to 5% Al2O3, 1% to 5% Na2O, 2% to 5% BaO, 1% to 6% CaO, and 0.5% to 7% K2O.

[0011] The inorganic additive is one or more of Bi2O3, CuO, and Li2O3.

[0012] The organic carrier consists of 80% to 90% of an organic solvent and 10% to 20% of a thickener.

[0013] Preferably, the fine-grained silver powder of the present invention has a particle size of less than 0.5 μm and a specific surface area of ​​20 to 30 m 2 / g; the particle size of the medium-sized silver powder is 0.5 to 2.0 μm, and the specific surface area is 6 to 10 m 2 / g; the coarse silver powder has a particle size of 2.5 to 5 μm and a specific surface area of ​​1 to 5 m 2 / g.

[0014] Preferably, the average particle size of the glass powder of the present invention after ball milling and screening is ≤3 μm.

[0015] Preferably, the softening temperature of the glass powder of the present invention is 420-470°C.

[0016] Preferably, the organic solvent in the organic carrier of the present invention is one or more of butyl carbitol, butyl acetate, terpineol, turpentine, n-butanol, toluene, and dibutyl phthalate; the thickener is one or more of ethyl cellulose, nitrocellulose, and polyisobutylene.

[0017] Another object of the present invention is to provide a method for preparing the high-adhesion 5G ceramic filter electrode silver paste, which specifically comprises the following steps:

[0018] (1) The raw materials for preparing glass powder are weighed and mixed in a certain proportion and placed in a box-type resistance furnace. The temperature is raised to 1200-1300°C for melting. The molten glass is water quenched, ball milled, and sieved to obtain glass powder that meets the particle size requirements and set aside.

[0019] (2) Weigh the organic solvent and thickener in proportion and place them in a constant temperature water bath (preferably 80° C.), stir them electrically until the mixture is completely dissolved, and finally cool them at room temperature to obtain an organic carrier for use.

[0020] (3) Mix silver powder, glass powder, inorganic additives and organic carrier in proportion, mix well and grind on a three-roll mill for 5 to 15 times to obtain a silver paste fineness of ≤5 μm.

[0021] Beneficial effects of the present invention:

[0022] (1) The Si-Zn-B glass powder selected in the present invention has a softening temperature of 420-470°C, a uniform particle size distribution, matches the expansion coefficient of the ceramic dielectric filter substrate, has a low sintering temperature, and has a high adhesion to the substrate; by adding a small amount of one or more of Bi2O3, CuO, and Li2O3, the softening point of the glass is reduced, the diffusion erosion of the glass relative to the functional ceramic body is inhibited, the segregation of the ceramic body components that affects the device function is prevented, the current carrying capacity of the metal layer is increased, and the good mechanical bonding strength of the silver paste after the ceramic metallization is improved.

[0023] (2) The conductive filler used in the present invention is composed of silver powders of different particle sizes. The silver powders of different particle sizes fill the gaps between each other during sintering, making the silver layer denser and further improving the adhesion. The viscosity, adhesion, leveling and thixotropy of the organic carrier used can be regulated to meet the requirements of dipping and spraying processes. The present invention mixes silver powder, glass powder, a recording body and an inorganic additive in a certain mass ratio and obtains a conductive silver paste after rolling. The conductive silver paste has the advantages of suitable viscosity and density. The unique glass powder formula and silver paste formula ensure that the surface of the silver layer after sintering will not fall off, have pores or be gray. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a scanning electron microscope image of the silver paste after sintering in Example 1;

[0025] Figure 2 This is a scanning electron microscope image of the silver paste after sintering in Example 2;

[0026] Figure 3 This is a scanning electron microscope image of the silver paste after sintering in Example 3. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0028] Example 1

[0029] The material of the 5G ceramic filter electrode silver paste with high adhesion in the present invention is selected from:

[0030] The weight ratios of fine-grained silver powder, medium-grained silver powder and coarse-grained silver powder used as the conductive filler are 25%, 50% and 25% respectively; and the mass fraction thereof is 75%.

[0031] The raw materials of glass powder are 10% SiO2, 35% ZnO, 30% B2O3, 5% Al2O3, 2.81% Na2O, 5% BaO, 6% CaO, 3.53% K2O, and the mass fraction of glass powder is 1.5%.

[0032] The raw materials of the organic carrier are 85% organic solvent, which is one or more of butyl carbitol, butyl acetate, terpineol, turpentine, n-butanol, toluene, and dibutyl phthalate; 15% thickener, which is one or more of ethyl cellulose, nitrocellulose, and polyisobutylene. The mass fraction of the organic carrier is 23%.

[0033] The inorganic additive is one or more of Bi2O3, CuO and Li2O3, and the mass fraction thereof is 0.5%.

[0034] This embodiment describes a method for preparing a 5G ceramic filter electrode silver paste, comprising the following steps:

[0035] (1) The raw materials for preparing glass powder are weighed according to a certain mass ratio. After preliminary mixing, all the weighed raw materials are placed in an agate grinding jar and ground in a ball mill for 4 hours at a speed of 250 r / min to fully mix the components. The ground powder is then sieved and dried. The evenly mixed powder is then placed in a clean and dried corundum crucible and melted in a box-type resistance furnace. The molten glass liquid is directly taken out and quickly poured into deionized water for water quenching. Finally, the block glass is taken out and placed in a drying oven for 8 hours to obtain glass solid particles. The obtained block glass is placed in a planetary ball mill for ball milling for 24 hours at a speed of 250 r / min. After ball milling, it is placed in a drying oven at 80°C for constant temperature drying for 12 hours. After screening, glass powder that meets the particle size requirements is obtained for use.

[0036] (2) Weigh a certain amount of organic solvent and thickener according to the mass ratio and place them in a beaker. Heat the beaker in a water bath at 80°C and stir in a sealed manner until the ethyl cellulose is completely dissolved. Finally, cool it to room temperature and store it in a sealed container. The desired organic carrier is then obtained.

[0037] (3) Silver powder, glass powder, inorganic additives, and organic carrier are weighed in a mortar according to the above mass percentages, ground thoroughly, and then ground using a three-roll mill for 5 to 15 times to obtain a silver paste.

[0038] The scanning electron microscope image of the silver paste prepared by the method described in this embodiment sintered on the ceramic sheet is as follows: Figure 1 As shown in the figure, it can be seen that although the silver layer is sintered densely, there are still holes.

[0039] Example 2

[0040] The material of the 5G ceramic filter electrode silver paste with high adhesion in the present invention is selected from:

[0041] The weight ratios of fine silver powder, medium silver powder and coarse silver powder used as conductive filler are 45%, 40% and 15% respectively, and the mass fraction is 80%.

[0042] The raw materials selected for the glass powder are 9.7% SiO2, 45.7% ZnO, 26.8% B2O3, 2% Al2O3, 2.81% Na2O, 2.83% BaO, 3.02% CaO, and 3.53% K2O, and the mass fraction of the glass powder is 1.5%.

[0043] The raw materials of the organic carrier are 90% organic solvent, which is one or more of butyl carbitol, butyl acetate, terpineol, turpentine, n-butanol, toluene, and dibutyl phthalate; 10% thickener, which is one or more of ethyl cellulose, nitrocellulose, and polyisobutylene. The mass fraction of the organic carrier is 14%.

[0044] The inorganic additive is one or more of Bi2O3, CuO and Li2O3, and the mass fraction thereof is 1.2%.

[0045] The method for preparing the above-mentioned 5G ceramic filter electrode silver paste comprises the following steps:

[0046] (1) The raw materials for preparing glass powder are weighed according to a certain mass ratio. After preliminary mixing, all the weighed raw materials are placed in an agate grinding jar and ground in a ball mill for 4 hours at a speed of 250 r / min to fully mix the components. The ground powder is then sieved and dried. The evenly mixed powder is then placed in a clean and dried corundum crucible and melted in a box-type resistance furnace. The molten glass liquid is directly taken out and quickly poured into deionized water for water quenching. Finally, the block glass is taken out and placed in a drying oven for 8 hours to obtain glass solid particles. The obtained block glass is placed in a planetary ball mill for ball milling for 24 hours at a speed of 250 r / min. After ball milling, it is placed in a drying oven at 80°C for constant temperature drying for 12 hours. After screening, glass powder that meets the particle size requirements is obtained for use.

[0047] (2) Weigh a certain amount of organic solvent and thickener according to the mass ratio and place them in a beaker. Heat the beaker in a water bath at 80°C and stir in a sealed manner until the ethyl cellulose is completely dissolved. Finally, cool it to room temperature and store it in a sealed container. The desired organic carrier is then obtained.

[0048] (3) Silver powder, glass powder, inorganic additives, and organic carrier are weighed in a mortar according to the above mass percentages, ground thoroughly, and then ground using a three-roll mill for 5 to 15 times to obtain a silver paste.

[0049] The scanning electron microscope image of the silver paste prepared by the method described in this embodiment sintered on the ceramic sheet is as follows: Figure 1 As shown in the figure, it can be seen that the silver layer is sintered densely with a small amount of holes; the silver paste does not peel, warp or crack after sintering.

[0050] Example 3

[0051] The material of the 5G ceramic filter electrode silver paste with high adhesion in the present invention is selected from:

[0052] The weight ratios of fine-grained silver powder, medium-grained silver powder and coarse-grained silver powder used as conductive fillers are 30%, 50% and 20% respectively; the mass fraction thereof is 85%.

[0053] The raw materials of glass powder are 5% SiO2, 50% ZnO, 30% B2O3, 1% Al2O3, 5% Na2O, 2.83% BaO, 3.02% CaO, 3.53% K2O, and the mass fraction of glass powder is 1.5%.

[0054] The raw materials selected for the organic carrier are 80% of organic solvent, which is one or more of butyl carbitol, butyl acetate, terpineol, turpentine, n-butanol, toluene, and dibutyl phthalate; 20% of thickener, which is one or more of ethyl cellulose, nitrocellulose, and polyisobutylene. The mass fraction of the organic carrier is 12%.

[0055] The inorganic additive is one or more of Bi2O3, CuO and Li2O3, and the mass fraction thereof is 1.5%.

[0056] The method for preparing the above-mentioned 5G ceramic filter electrode silver paste comprises the following steps:

[0057] (1) The raw materials for preparing glass powder are weighed according to a certain mass ratio. After preliminary mixing, all the weighed raw materials are placed in an agate grinding jar and ground in a ball mill for 4 hours at a speed of 250 r / min to fully mix the components. The ground powder is then sieved and dried. The evenly mixed powder is then placed in a clean and dried corundum crucible and melted in a box-type resistance furnace. The molten glass liquid is directly taken out and quickly poured into deionized water for water quenching. Finally, the block glass is taken out and placed in a drying oven for 8 hours to obtain glass solid particles. The obtained block glass is placed in a planetary ball mill for ball milling for 24 hours at a speed of 250 r / min. After ball milling, it is placed in a drying oven at 80°C for constant temperature drying for 12 hours. After screening, glass powder that meets the particle size requirements is obtained for use.

[0058] (2) Weigh a certain amount of organic solvent and thickener according to the mass ratio and place them in a beaker. Heat the beaker in a water bath at 80°C and stir in a sealed manner until the ethyl cellulose is completely dissolved. Finally, cool it to room temperature and store it in a sealed container. The desired organic carrier is then obtained.

[0059] (3) Silver powder, glass powder, inorganic additives, and organic carrier are weighed in a mortar according to the above mass percentages, ground thoroughly, and then ground using a three-roll mill for 5 to 15 times to obtain a silver paste.

[0060] The scanning electron microscope image of the silver paste prepared by the method described in this embodiment sintered on the ceramic sheet is as follows: Figure 1 As shown in the figure, it can be seen that there are holes and steps in the sintering, and the sintering is not very uniform.

[0061] The properties of the silver medals prepared in different embodiments are shown in Table 1.

[0062]

[0063] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A 5G ceramic filter electrode silver paste with high adhesion, characterized in that: Made of the following raw materials in percentage by mass: Conductive filler 75%~85%; Glass powder 1% to 3.5%; Inorganic additives 0.5% to 2%; Organic carrier 12% to 23%; The conductive filler is composed of three kinds of spherical silver powders with different particle sizes, wherein the weight ratios of fine silver powder, medium silver powder and coarse silver powder are 45%, 40% and 15% respectively; The glass powder comprises, by weight percentage, 5% to 10% SiO2, 35% to 50% ZnO, 20% to 30% B2O3, 1% to 5% Al2O3, 1% to 5% Na2O, 2% to 5% BaO, 1% to 6% CaO, and 0.5% to 7% K2O; The inorganic additive is one or more of Bi2O3 and CuO; The organic carrier is composed of 80% to 90% of an organic solvent and 10% to 20% of a thickener; The fine silver powder has a particle size of less than 0.5 μm and a specific surface area of ​​20 to 30 m 2 / g; the particle size of the medium-sized silver powder is 0.5 to 2.0 μm, and the specific surface area is 6 to 10 m 2 / g; the coarse silver powder has a particle size of 2.5 to 5 μm and a specific surface area of ​​1 to 5 m 2 / g; The method for preparing the high-adhesion 5G ceramic filter electrode silver paste is prepared according to the following steps: (1) The raw materials for preparing glass powder are weighed and mixed in a certain proportion and placed in a box-type resistance furnace. The temperature is raised to 1200-1300° C. for melting. The molten glass is water quenched, ball milled, and sieved to obtain glass powder that meets the particle size requirements for use; (2) weighing an organic solvent and a thickener in a certain proportion, stirring the mixture in a constant temperature water bath until the mixture is completely dissolved, and finally cooling the mixture at room temperature to obtain an organic carrier for use; (3) silver powder, glass powder, inorganic additives and organic carrier are mixed in proportion, and after mixing evenly, the mixture is fully ground on a three-roll mill until the fineness of the silver paste is ≤5 μm.

2. The high-adhesion 5G ceramic filter electrode silver paste according to claim 1, characterized in that: The average particle size of the glass powder after ball milling and screening is ≤3 μm.

3. The high-adhesion 5G ceramic filter electrode silver paste according to claim 1, characterized in that: The softening temperature of the glass powder is 420-470°C.

4. The high-adhesion 5G ceramic filter electrode silver paste according to claim 1, characterized in that: The organic solvent is one or more of butyl carbitol, butyl acetate, terpineol, turpentine, n-butanol, toluene, and dibutyl phthalate; the thickener is one or more of ethyl cellulose, nitrocellulose, and polyisobutylene.

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