阅读说明：本技术 一种5g陶瓷介质滤波器用强附着力银导体浆料 (Strong-adhesion silver conductor paste for 5G ceramic dielectric filter ) 是由 党丽萍 鹿宁 赵科良 王顺顺 赵莹 王大林 王明奎 张亚鹏 于 2021-04-19 设计创作，主要内容包括：本发明公开了一种5G陶瓷介质滤波器用强附着力银导体浆料,所述银导体浆料的重量百分比组成为：球状银粉55%～70%,片状银粉6%～20%,玻璃粉0.5%～3%,热处理后的活性白云石粉与冰晶石粉混合物0.2%～2%,有机载体8%～15%,浆料改性剂1%～5%,有机稀释剂5%～11%。本发明中对白云石粉和冰晶石粉原料进行热处理后,形成活性白云石粉及冰晶石粉混合物加入到导电银浆中,最终得到高附着力银导体浆料,且拉拨处不起皮,同时经测试可焊性好,导电优良。本发明银导体浆料应用于系列5G陶瓷介质滤波器瓷片上后,流平性较好,金属化膜层平整,提升附着力的同时,兼顾了浆料的导电性能,可有效降低滤波器的插入损耗,使滤波器有较高的品质因数。(The invention discloses a strong-adhesion silver conductor paste for a 5G ceramic dielectric filter, which comprises the following components in percentage by weight: 55-70% of spherical silver powder, 6-20% of flake silver powder, 0.5-3% of glass powder, 0.2-2% of a mixture of heat-treated active dolomite powder and cryolite powder, 8-15% of an organic carrier, 1-5% of a slurry modifier and 5-11% of an organic diluent. In the invention, after the dolomite powder and the cryolite powder are subjected to heat treatment, a mixture of active dolomite powder and cryolite powder is formed and added into the conductive silver paste, and finally the high-adhesion silver conductor paste is obtained, and the pulling and pulling part is not peeled, and meanwhile, the soldering performance is good and the conductivity is excellent through tests. After the silver conductor slurry is applied to the series of 5G ceramic dielectric filter ceramic chips, the leveling property is good, the metalized film layer is smooth, the adhesive force is improved, the conductive performance of the slurry is considered, the insertion loss of the filter can be effectively reduced, and the filter has a high quality factor.)

1. The strong-adhesion silver conductor slurry for the 5G ceramic dielectric filter is characterized by comprising the following raw materials in percentage by weight: 55-70% of spherical silver powder, 6-20% of flake silver powder, 0.5-3% of glass powder, 0.2-2% of a mixture of heat-treated active dolomite powder and cryolite powder, 8-15% of an organic carrier, 1-5% of a slurry modifier and 5-11% of an organic diluent;

the mixture of the activated dolomite powder and the cryolite powder after the heat treatment is obtained by uniformly mixing the dolomite powder and the cryolite powder according to the weight ratio of 1:1 and then performing heat treatment for 60-90 minutes at 150-180 ℃.

2. The strongly adherent silver conductor paste for a 5G ceramic dielectric filter according to claim 1, wherein: the weight percentage of the active dolomite powder and cryolite powder mixture after heat treatment in the slurry is 0.4-1.0%, and the average particle size range is 0.3-1.0 μm.

3. The strongly adherent silver conductor paste for a 5G ceramic dielectric filter according to claim 1, wherein: the spherical silver powder has an average particle diameter of 0.7 to 1.15 [ mu ] m and a tap density of 4.5 to 5.5g/cm, and the flake-like silver powder has an average particle diameter of 0.8 to 5.0 [ mu ] m and a tap density of 4.0 to 7.0g/cm³。

4. The strongly adherent silver conductor paste for a 5G ceramic dielectric filter according to claim 1, wherein: the glass powder is Ca-B-Si series glass, and the particle size of the glass powder is 1.0-1.8 mu m.

5. The strongly adherent silver conductor paste for a 5G ceramic dielectric filter according to claim 1, wherein: the organic carrier is composed of the following raw materials in percentage by weight: 5-25% of resin and 75-95% of organic solvent, wherein the resin is one or more of rosin resin, terpene resin, maleic acid resin, polyvinyl butyral and ethyl cellulose, and the organic solvent is one or more of terpineol, diethylene glycol dibutyl ether and butyl carbitol acetate.

6. The strongly adherent silver conductor paste for a 5G ceramic dielectric filter according to claim 1, wherein: the slurry modifier is composed of a thixotropic agent, a dispersing agent and an antifoaming agent according to a mass ratio of 1:1:1, wherein the thixotropic agent is hydrogenated castor oil or polyethylene wax, the dispersing agent is triammonium citrate or ammonium polymethacrylate, and the antifoaming agent is tributyl phosphate or polydimethylsiloxane.

7. The strongly adherent silver conductor paste for a 5G ceramic dielectric filter according to claim 1, wherein: the organic diluent is any one of diethylene glycol dimethyl ether, DBE and dimethylformamide.

Technical Field

The invention belongs to the technical field of silver conductor paste for a 5G ceramic dielectric filter, and particularly relates to silver conductor paste with strong adhesive force, which is suitable for the 5G ceramic dielectric filter.

Background

With the development of mobile communication networks, radio frequency bands have become very dense. The requirements of miniaturization, low loss, stable and reliable performance and the like are about to be the mainstream pursued by 5G communication. The 5G ceramic dielectric filter becomes the mainstream filter in the 5G era due to the advantages of small volume, small loss, high Q value and the like. By virtue of the excellent performance, the method has wider application space in the field of mobile communication. In order to improve the performance of the ceramic dielectric filter, a silver paste layer is coated on the surface of the ceramic dielectric filter. Thus, metallization is one of the key technologies for ceramic dielectric filters, and has a direct impact on the performance and reliability of the filter.

The conductor paste is mainly prepared from raw materials such as conductive phase silver powder, bonding phase glass powder, an inorganic additive, an organic carrier, an organic additive and the like, and the high-frequency loss of the filter is required to be reduced besides the requirement on high adhesive force of the silver conductor paste for the 5G ceramic dielectric filter, so that special requirements are provided for the compactness and the conductivity of a silver electrode, the components of the glass powder for silver paste and the inorganic additive. However, the silver conductor slurry for the existing 5G ceramic dielectric filter is mainly poor in combination with a ceramic body after being sintered and has the phenomenon of large-area falling off in the use process.

In the known invention of the silver conductor paste for the 5G ceramic dielectric filter, the bismuth-containing glass powder commonly used for lead-free silver conductor paste and the conventional oxides or a plurality of groups of oxides such as zinc oxide, bismuth oxide, aluminum oxide, yttrium oxide and the like are adopted. Conventional oxides do provide good adhesion to silver pastes due to the reaction of the oxide with the ceramic matrix of the filter resulting in better bond strength. However, after the oxide reacts with the filter ceramic, the Q value and the insertion loss of the filter are affected, and the problems of large tensile force, poor electrical properties of the Q value, the insertion loss and the like occur.

Disclosure of Invention

The invention aims to provide silver conductor paste which has strong adhesive force and can effectively reduce insertion loss for a 5G ceramic dielectric filter.

Aiming at the purposes, the silver conductor paste is characterized by comprising the following raw materials in percentage by weight: 55-70% of spherical silver powder, 6-20% of flake silver powder, 0.5-3% of glass powder, 0.2-2% of a mixture of heat-treated active dolomite powder and cryolite powder, 8-15% of an organic carrier, 1-5% of a slurry modifier and 5-11% of an organic diluent, wherein the mixture of heat-treated active dolomite powder and cryolite powder is obtained by uniformly mixing dolomite powder and cryolite powder according to a weight ratio of 1:1 and then carrying out heat treatment at 150-180 ℃ for 60-90 minutes.

In the slurry, the mixture of the activated dolomite powder and the cryolite powder after the heat treatment accounts for 0.4 to 1.0 percent by weight, and the average particle size ranges from 0.3 to 1.0 mu m.

The spherical silver powder has an average particle diameter of 0.7 to 1.15 μm and a tap density of 4.5 to 5.5g/cm, and the flaky silver powder has an average particle diameter of 0.8 to 5.0 μm and a tap density of 4.0 to 7.0g/cm³。

The glass powder is Ca-B-Si glass, and the particle size of the glass powder is 1.0-1.8 μm.

The organic carrier consists of the following raw materials in percentage by weight: 5-25% of resin and 75-95% of organic solvent, wherein the resin is one or more of rosin resin, terpene resin, maleic acid resin, polyvinyl butyral and ethyl cellulose, and the organic solvent is one or more of terpineol, diethylene glycol dibutyl ether and butyl carbitol acetate.

The slurry modifier consists of a thixotropic agent, a dispersing agent and an antifoaming agent according to the mass ratio of 1:1:1, wherein the thixotropic agent is hydrogenated castor oil or polyethylene wax, the dispersing agent is triammonium citrate or ammonium polymethacrylate, and the antifoaming agent is tributyl phosphate or polydimethylsiloxane.

The organic diluent is a low boiling point solvent such as: diethylene glycol dimethyl ether, DBE, dimethylformamide and the like, which are used for dilution to adjust viscosity.

The preparation method of the silver conductor paste comprises the following steps:

1. uniformly mixing dolomite powder and cryolite powder according to the weight ratio of 1:1, carrying out heat treatment at 150-180 ℃ for 60-90 minutes, and then cooling to normal temperature to obtain a mixture of the heat-treated active dolomite powder and the cryolite powder.

2. Preparing glass powder: weighing oxides according to a proportion, fully mixing the oxides uniformly, placing the mixture in an oven at 100-230 ℃ for drying for 1-2 hours, then smelting the mixture at 1000-1200 ℃ for 2 hours, quenching the molten glass uniformly to obtain glass coarse particles, adding the glass coarse particles into a polyurethane tank for ball milling for 10-15 hours to obtain powder with the average particle size of 1.0-1.8 mu m, and drying the powder at 125 ℃ to obtain the glass powder.

3. Preparation of organic vehicle: heating the organic solvent to 60-90 ℃, sequentially adding the resin while stirring, continuously stirring for 1-2 hours until the resin is dissolved, and finally forming a transparent homogeneous solution, namely the organic carrier.

4. The preparation method of the silver conductor paste comprises the following steps: dividing the organic carrier into two parts, and adding a mixture of weighed glass powder, thermally treated dolomite powder and cryolite powder into one part of the organic carrier according to the formula proportion of the silver conductor slurry to be mixed in advance to obtain a paste I; and adding the spherical silver powder, the flaky silver powder, the slurry modifier and the premixed paste I into another part of organic carrier, mixing by using a stirring dispersion machine, fully grinding and rolling on a three-roller machine after uniformly mixing, adding an organic diluent into the rolled semi-finished product according to the viscosity requirement to adjust the semi-finished product to a proper viscosity value, filtering by using a filter screen cloth of more than 500 meshes, and packaging to obtain the silver conductor slurry with the fineness of less than or equal to 8 microns.

The invention has the following beneficial effects:

1. according to the invention, the spherical silver powder and the flake silver powder are matched for use, and the micron-sized spherical powder is used for filling gaps existing in the lapping of the flake silver powder, so that a conductive path between powder bodies is enlarged, the compactness of a silver layer after sintering is improved, the adhesive force is further improved, and the electrical property of the silver layer is ensured.

2. According to the invention, the dolomite powder and cryolite powder mixture is subjected to heat treatment and then used as an adhesive force additive to reduce the moisture of the powder, and meanwhile, the heat treatment can recrystallize the active dolomite powder and active cryolite powder mixture, so that the resistance of the mixed powder is reduced, the bonding strength of an inorganic material and a ceramic body is improved, and the silver paste is ensured to have good adhesive force on the premise of not influencing the electrical property. The ceramic dielectric filter is sintered at high temperature of about 850 ℃ to form strong chemical bonding with microwave dielectric ceramic, and meanwhile, the ceramic dielectric filter does not cause component pollution influence on the base material, and can keep a 5G ceramic dielectric filter to have good Q value and low insertion loss.

3. The Ca-B-Si glass is selected, the melting point of the glass powder is 580-680 ℃, and the Ca-B-Si glass is suitable for a high-temperature sintering process of a silver electrode; the silver conductor paste can effectively ensure that the silver conductor paste has good wettability with the porcelain body after sintering, ensures that the silver metal powder is in contact with the porcelain body to form good adhesive force, and does not reduce the quality factor (Q) of the porcelain body.

4. According to the silver conductor slurry, silver powder is mixed and matched, the mixture of the active dolomite powder and the cryolite powder after heat treatment and glass powder interact, so that a silver layer is more compact after sintering, the conductivity is good, the binding force of the silver layer and a porcelain body is strong, and meanwhile, the weldability of the silver layer is good. Because the glass powder of the high-temperature wetted porcelain body reacts with the porcelain body, the filter has high reliability, and simultaneously ensures high frequency, low insertion loss and high Q value of the device.

5. The silver conductor paste is coated on the surface of a ceramic medium by methods of screen printing, integral silver immersion or surface silver spraying and the like, and forms a conductive electrode on the surface of the filter ceramic after being sintered at 850 +/-50 ℃, the adhesion of the electrode is strong, the conductivity is good, and the adhesion of a silver layer is more than 30N/mm²And the pulling-stripping part does not peel and leak porcelain, and can be directly welded for use.

Detailed Description

The present invention will be described in further detail with reference to examples, but the scope of the present invention is not limited to these examples.

Examples 1 to 5

100g of the silver conductor paste of examples 1 to 5 was prepared according to the formulation in Table 1, and the specific preparation method was as follows:

1. weighing dolomite powder and cryolite powder according to the weight ratio of 1:1, uniformly mixing, carrying out heat treatment at 160 ℃ for 70 minutes, and then cooling to normal temperature to obtain a heat-treated active dolomite powder and cryolite powder mixture with the particle size range of 0.3-1.0 mu m.

2. Preparation of Ca-B-Si glass powder: oxide is 13 percent by weight of B₂O₃、42% SiO₂、40%CaO、4% Al₂O₃Weighing 1% of MgO in proportion, fully and uniformly mixing, placing in an oven at 150 ℃ for drying for 2 hours, then smelting at 1150 ℃ for 2 hours, water-quenching the molten and uniformly-melted glass to obtain coarse glass particles, adding the coarse glass particles into a polyurethane tank for ball milling for 12 hours, and drying at 125 ℃ to obtain Ca-B-Si series glass powder with the particle size of 1.0-1.8 mu m.

3. Preparation of organic vehicle: according to the weight percentage of the organic carrier, 60wt% of terpineol and 20wt% of butyl carbitol acetate are fully and uniformly mixed, then the mixture is heated to 65 ℃, 4wt% of ethyl cellulose and 16wt% of terpene resin are sequentially added under stirring, the mixture is continuously stirred for 2 hours until the mixture is dissolved, and finally, a transparent homogeneous solution is formed, namely the organic carrier.

4. The preparation method of the silver conductor paste comprises the following steps: averagely dividing the organic carrier prepared in the step 3 into two parts, firstly adding the mixture of Ca-B-Si glass powder, the activated dolomite powder after heat treatment and the cryolite powder into one part of the organic carrier, and premixing to obtain a paste I; and a spherical silver powder (average particle diameter of 0.7 to 1.15 μm, tap density of 4.5 to 5.5 g/cm), a flake silver powder (average particle diameter of 0.8 to 5.0 μm, tap density of 4.0 to 7.0 g/cm)³) Adding a slurry modifier (consisting of hydrogenated castor oil, polymethacrylic acid amine and tributyl phosphate according to the mass ratio of 1:1: 1) and the premixed paste I into another part of organic carrier, mixing by using a stirring dispersion machine, uniformly mixing, and then putting the mixture into a three-roller machineFully grinding and rolling, adding diethylene glycol dimethyl ether into the rolled semi-finished slurry according to the viscosity requirement to adjust the viscosity value to be 4.0-15.0 Pa.s, filtering with 500-mesh filter screen cloth, and packaging to obtain the silver conductor slurry with the fineness of less than or equal to 8 mu m.

TABLE 1

Meanwhile, 100g of silver conductor paste is prepared by the weight percentage composition of comparative examples 1-6 in the table 1 and the method, and a control experiment is carried out.

The silver conductor slurry is coated on a 17mm 16mm 6mm ceramic body through a metallization process in a dipping mode, after the ceramic body is naturally leveled for 10min, the ceramic body is dried for 10min at 180 ℃, a sample is placed in a belt sintering furnace at 850 +/-50 ℃ for sintering, the sintering period is 90min, the peak value is kept for 12min, and after a test sample is prepared, detection is carried out, and the result is shown in table 2.

TABLE 2 test results

As can be seen from table 2, the silver paste prepared in embodiments 1 to 5 of the present invention, to which the mixture of the activated dolomite powder and the cryolite powder after the heat treatment is added, has a silver paste adhesion significantly better than that of a mixture without heat treatment or better than that of a mixture without heat treatment alone, and has good conductivity, a higher Q value, and high reliability. Comparing example 5 with the silver conductor slurry prepared by directly adding untreated dolomite powder or cryolite powder in comparative examples 1 and 2, the silver layer is more densely sintered after the heat-treated active dolomite powder and cryolite powder mixture is added, which is more beneficial to the growth of silver grains, and the silver layer is not peeled off; comparing the example 5 with the comparative example 3, the silver conductor slurry prepared by adding the untreated dolomite powder and cryolite powder mixture is compared with the active dolomite powder and cryolite powder mixture after introducing the heat treatment, the overall characteristics of the slurry are comprehensively improved, the slurry has better electrical performance, and the adhesive force is obviously improved; compared with the comparative examples 4 to 6, in the case that the addition amount of the silver powder is the same, the spherical silver powder and the flake silver powder are adopted, and the silver powder is only suitable for any one of the spherical silver powder and the flake silver powder, so that the silver layer density after the conductive silver paste is sintered is improved through filling gaps between the flake silver powder and the spherical silver powder, the adhesive force is further improved, and the electrical property of the conductive silver paste is ensured.