Conductive silver paste for LTCC hole filling and preparation method thereof

Abstract

The invention discloses conductive silver paste for LTCC hole filling. The conductive silver paste comprises the following raw materials in percentage by weight: 82-92% of conductive phase silver powder, 5-9% of an organic solvent, 0.5-4% of organic particles, 0.5-3% of organic resin, 0.3-2% of an organic additive and 0.01-1% of an inorganic additive. According to the conductive silver paste for LTCC hole filling and the preparation method of the conductive silver paste, the cofiring shrinkage matching performance of the conductive silver paste and an LTCC base body is mainly considered, and the particle size selection and proportion of the silver powder and the inorganic particles are designed and optimized, so that the conductive silver paste can obtain good conductivity and silver layer compactness under the low-temperature sintering condition in the air; and the material can be well matched with LTCC substrates with different thicknesses and different apertures.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive silver paste, in particular to a conductive silver paste for LTCC hole filling and a preparation method thereof. Background Art

[0002] With the rapid development of modern electronic information technology, the demand for miniaturization, integration, modularization, multifunctionality, high performance, and high reliability of electronic components has become increasingly urgent. This is why LTCC (low-temperature co-fired ceramic) technology has emerged. Developed in 1982 by Hughes Aircraft Company in the United States, LTCC is a novel material technology. It forms a dense, green tape of precisely defined thickness from low-temperature sintered ceramic powder. Laser drilling, microporous grouting, and precision conductive paste printing are used to create the desired circuit patterns. Multiple passive components are embedded in a multilayer ceramic substrate, which is then laminated and sintered at 900°C to form a high-density circuit with no interference in three dimensions. LTCC is a multidisciplinary integrated component technology. Due to its excellent electronic, mechanical, and thermal properties, it has become the preferred method for miniaturization, integration, and modularization of electronic components, and is widely used in integrated devices, microwave technology, and other fields.

[0003] At present, the domestic LTCC industry is gradually developing. Although some manufacturers have begun to produce products, there is still no representative series of conductive silver paste for LTCC hole filling. Based on this, the present invention provides a conductive silver paste for LTCC hole filling and a preparation method thereof. Summary of the Invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a conductive silver paste for LTCC hole filling and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] The present invention solves the technical problem by adopting the following technical solutions: The present invention provides a conductive silver paste for LTCC hole filling, comprising the following raw materials in percentage by weight: 82~92% conductive silver powder, 5~9% organic solvent, 0.5~4% organic particles, 0.5~3% organic resin, 0.3~2% organic additives, 0.01~1% inorganic additives.

[0006] Preferably, the organic solvent includes one or more of alcohols or ethers, the organic resin includes one or more of ethyl cellulose, cellulose acetate, and acrylic resin, and the organic additive includes one or more of a dispersant, a leveling agent, a plasticizer, and a coupling agent.

[0007] Preferably, the alcohol is ethanol; the ether is diethylene glycol dimethyl ether; the organic microparticles are polymethyl methacrylate microspheres; the dispersant is polyether phosphate; the coupling agent is silane coupling agent KH560; the plasticizer is tributyl citrate; and the leveling agent is an organic silicone leveling agent.

[0008] Preferably, the inorganic additive is a rare earth-doped modified additive, and the specific preparation method is: S1: heat-treat rare earth cerium at 110-130°C for 10 min, then heat to 220°C at a rate of 2-4°C / min, hold for 5 min, and finally air-cool to room temperature; Immerse the cerium cooled to room temperature in a modification solution 3-5 times the total amount of cerium, stirring and modifying the solution, stirring until the solution is modified to obtain a modified cerium solution; The preparation method of the modified liquid is: Blend 2-3 parts of silane coupling agent KH550 and 1-3 parts of sodium dodecylbenzenesulfonate solution into 5-8 parts of lanthanum chloride solution, then add 2-4 parts of zirconium oxide, stir thoroughly, and obtain a modified solution; S2: The modified cerium solution and the additive are mixed in a weight ratio of 5:3 and ball-milled at a ball-milling speed of 1000 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a rare earth-doped modified additive.

[0009] Preferably, the mass fraction of the sodium dodecylbenzenesulfonate solution is 2-5%; the mass fraction of the lanthanum chloride solution is 4-7%.

[0010] Preferably, the stirring speed of the stirring modification treatment is 450-500 r / min, and the stirring time is 20-30 min.

[0011] Preferably, the preparation method of the additive is: S11: Silicon carbide, sodium silicate solution and dopamine hydrochloride solution are mixed in a weight ratio of 3:2:5 to obtain silicon carbide liquid; S12: 3-5 parts of yttrium oxide, 2-4 parts of scandium and 5-8 parts of silicon carbide liquid are mixed and ultrasonically treated. After the ultrasonic treatment is completed, the mixture is filtered and dried to obtain an additive.

[0012] The rare earth-doped modified additive is made of rare earth cerium through thermal improvement, and then improved with the modifying liquid. The lanthanum chloride solution, zirconium oxide silane coupling agent KH550 and other raw materials in the modifying liquid are improved through the blending between the raw materials, and then improved by ball milling of the additives. The silicon carbide in the additives is combined with sodium silicate solution and dopamine hydrochloride solution, and the scandium and silicon carbide liquid are specifically improved. The obtained rare earth-doped modified additive is added to the system to optimize the conductivity of the silver paste.

[0013] The mass fraction of the sodium silicate solution is 2-5%; the mass fraction of the dopamine hydrochloride solution is 4-7%; the ultrasonic power of the blending ultrasonic treatment is 350-400W, and the ultrasonic treatment lasts for 20 minutes.

[0014] The present invention also provides a method for preparing a conductive silver paste for LTCC hole filling, comprising the following steps: The organic resin and the organic solvent are mixed, heated and stirred, and then filtered under positive pressure to obtain the desired organic carrier; The organic additive, the organic carrier, the inorganic additive, the organic particles, the conductive silver powder and the organic solvent are uniformly mixed to obtain a premix; The premix is ​​fully dispersed by a three-roll mill grinding and dispersion method to obtain a pre-finished product, and then the premix is ​​filtered and homogenized under positive pressure to obtain the conductive silver paste for LTCC hole filling.

[0015] Preferably, the electric heating temperature for hot melt stirring is 70-90° C., the stirring speed is set to 200-400 RPM, and the heating stirring time is 12-24 hours.

[0016] The premix is ​​dispersed 8 to 12 times in a three-roll mill, with the roller spacing decreasing gradually from large to small, and the viscosity control range is 1200 to 2500 Kcps.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a conductive silver paste for filling holes in LTCC and a preparation method thereof. The present invention primarily considers the compatibility of the conductive silver paste with the shrinkage rate of the LTCC substrate during co-firing, optimizes the particle size selection and ratio of the silver powder and the inorganic particles, so that the conductive silver paste can obtain good conductivity and silver layer density under low-temperature sintering conditions in air, and can well match LTCC substrates of different thicknesses and pore sizes. Conductive silver paste is made by adding organic carriers and some organic additives to ensure that all raw materials in the formula can be evenly dispersed and not agglomerated after mixing, grinding and dispersion, and has good rheological properties and printing performance. The role of inorganic additives is to further improve the printability and permeability of the conductive silver paste.

[0018] Silver powder acts as a functional conductive phase, and together with the organic particles, it plays a role in controlling the shrinkage rate. In addition, the conductive silver paste of the present invention does not add glass powder. It mainly relies on the physical and chemical reactions between the silver powder and the ceramic matrix during the sintering process to achieve bonding. The basic principle is as follows: the melting point of silver is 961.93°C. Generally speaking, due to its high activity, the melting point of micron-sized silver powder is about 700-800°C, which is much lower than that of pure silver. Some nano-sized silver powders have a sintering temperature of 200-300°C. Therefore, the present invention does not add glass powder, but relies on the melting, flow, grain growth of the silver powder during the sintering process and the chemical reaction with the matrix to obtain good bonding strength. Specifically, after reaching the melting point during the sintering process, the silver powder begins to flow and fills into the tiny pores on the surface of the matrix to bond with the matrix. At the same time, there are some chemical reactions between the silver powder and some substances in the ceramic matrix. For example, silver reacts with components such as the glass phase in the ceramic matrix to form intermetallic compounds or solid solutions, thereby enhancing the bonding between the silver layer and the matrix. Application publication number CN 112614608 A mentions "a conductive silver paste for low-temperature co-fired ceramics and its preparation method." The patent mentions that the main material silver powder used in the conductive silver paste is 450-550nm spherical silver powder. The present invention uses spherical silver powder with a larger particle size, including one or more of three spherical silver powders with an average particle size of 0.8μm, 3.6μm and 6μm. All three types of silver powder are domestically produced materials, which have more cost advantages.

[0019] Patent application publication number CN 115798781 A mentions "A LTCC Conductive Silver Paste and Its Preparation Method." The raw materials used in the electrode silver paste described in the article include glass powder, but the role of the glass powder is not further explained. Generally speaking, glass powder in conductive silver paste serves as a sintering aid and binder, but the conductive silver paste described in the present invention does not require the addition of glass powder. Silver has a melting point of 961.93°C. Generally speaking, micron-sized silver powder has a melting point of approximately 700-800°C, much lower than pure silver due to its high activity. Some nano-sized silver powders even have a sintering temperature of 200-300°C. Therefore, the present invention does not add glass powder, relying instead on the silver powder's melting, flow, grain growth, and chemical reaction with the substrate during the sintering process to achieve good bonding strength. Specifically, after reaching its melting point during the sintering process, the silver powder begins to flow and fills the tiny pores on the substrate surface, bonding to the substrate. At the same time, there are some chemical reactions between silver powder and some substances in the ceramic matrix. For example, silver reacts with the glass phase components in the ceramic matrix to form intermetallic compounds or solid solutions, thereby enhancing the bonding between the silver layer and the matrix.

[0020] Patent application publication number CN 113782250 A mentions "a high thixotropic low-temperature co-fired ceramic inner electrode silver paste, its preparation method and application". The inner electrode silver paste described in the article is a silver paste for printed conductive circuit inner electrodes, which is inconsistent with the application direction of the conductive silver paste for hole filling of the present invention. In addition, the conductive silver paste of the present invention can be applied to LTCC substrates with different pore sizes. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] The conductive silver paste for LTCC hole filling of this embodiment includes the following raw materials in percentage by weight: 82~92% conductive silver powder, 5~9% organic solvent, 0.5~4% organic particles, 0.5~3% organic resin, 0.3~2% organic additives, 0.01~1% inorganic additives.

[0023] The organic solvent of this embodiment includes one or more of alcohols or ethers, the organic resin includes one or more of ethyl cellulose, cellulose acetate, and acrylic resin, and the organic additive includes one or more of a dispersant, a leveling agent, a plasticizer, and a coupling agent.

[0024] In this embodiment, the alcohol is ethanol; the ether is diethylene glycol dimethyl ether; the organic particles are polymethyl methacrylate microspheres; the dispersant is polyether phosphate; the coupling agent is silane coupling agent KH560; the plasticizer is tributyl citrate; and the leveling agent is an organic silicone leveling agent.

[0025] The inorganic additive of this embodiment is a rare earth-doped modified additive, and the specific preparation method is as follows: S1: heat-treat rare earth cerium at 110-130°C for 10 min, then heat to 220°C at a rate of 2-4°C / min, hold for 5 min, and finally air-cool to room temperature; Immerse the cerium cooled to room temperature in a modification solution 3-5 times the total amount of cerium, stirring and modifying the solution, stirring until the solution is modified to obtain a modified cerium solution; The preparation method of the modified liquid is: Blend 2-3 parts of silane coupling agent KH550 and 1-3 parts of sodium dodecylbenzenesulfonate solution into 5-8 parts of lanthanum chloride solution, then add 2-4 parts of zirconium oxide, stir thoroughly, and obtain a modified solution; S2: The modified cerium solution and the additive are mixed in a weight ratio of 5:3 and ball-milled at a ball-milling speed of 1000 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a rare earth-doped modified additive.

[0026] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 2-5%; the mass fraction of the lanthanum chloride solution is 4-7%.

[0027] The stirring speed of the stirring modification treatment in this embodiment is 450-500 r / min, and the stirring is carried out for 20-30 minutes.

[0028] The preparation method of the additive of this embodiment is: S11: Silicon carbide, sodium silicate solution and dopamine hydrochloride solution are mixed in a weight ratio of 3:2:5 to obtain silicon carbide liquid; S12: 3-5 parts of yttrium oxide, 2-4 parts of scandium and 5-8 parts of silicon carbide liquid are mixed and ultrasonically treated. After the ultrasonic treatment is completed, the mixture is filtered and dried to obtain an additive.

[0029] The mass fraction of the sodium silicate solution is 2-5%; the mass fraction of the dopamine hydrochloride solution is 4-7%; the ultrasonic power of the blending ultrasonic treatment is 350-400W, and the ultrasonic treatment lasts for 20 minutes.

[0030] The method for preparing a conductive silver paste for LTCC hole filling of this embodiment includes the following steps: The organic resin and the organic solvent are mixed, heated and stirred, and then filtered under positive pressure to obtain the desired organic carrier; The organic additive, the organic carrier, the inorganic additive, the organic particles, the conductive silver powder and the organic solvent are uniformly mixed to obtain a premix; The premix is ​​fully dispersed by a three-roll mill grinding and dispersion method to obtain a pre-finished product, and then the premix is ​​filtered and homogenized under positive pressure to obtain the conductive silver paste for LTCC hole filling.

[0031] In this embodiment, the electric heating temperature of the hot melt stirring is 70-90° C., the stirring speed is set to 200-400 RPM, and the heating stirring time is 12-24 hours.

[0032] The premix is ​​dispersed 8 to 12 times in a three-roll mill, with the roller spacing decreasing gradually from large to small, and the viscosity control range is 1200 to 2500 Kcps.

[0033] Example 1. The conductive silver paste for LTCC hole filling of this embodiment includes the following raw materials in percentage by weight: 82% conductive silver powder, 5% organic solvent, 0.5% organic particles, 0.5% organic resin, 0.3% organic additives, 0.01% inorganic additives.

[0034] In this embodiment, the organic solvent includes alcohols, the organic resin includes ethyl cellulose, and the organic additives include a dispersant, a leveling agent, a plasticizer, and a coupling agent, wherein the dispersant, the leveling agent, the plasticizer, and the coupling agent are compounded in a weight ratio of 1:1:1:1. In this embodiment, the alcohol is ethanol; the ether is diethylene glycol dimethyl ether; the organic particles are polymethyl methacrylate microspheres; the dispersant is polyether phosphate; the coupling agent is silane coupling agent KH560; the plasticizer is tributyl citrate; and the leveling agent is an organic silicone leveling agent.

[0035] The inorganic additive of this embodiment is a rare earth-doped modified additive, and the specific preparation method is as follows: S1: The rare earth cerium was heat treated at 110°C for 10 min, then heated to 220°C at a rate of 2°C / min, kept at this temperature for 5 min, and finally cooled to room temperature in air; Immerse the cerium cooled to room temperature in a modification solution 3 times the total amount of cerium, stirring and modifying the solution, stirring until the solution is modified, and obtain a modified cerium solution; The preparation method of the modified liquid is: 2 parts of silane coupling agent KH550 and 1 part of sodium dodecylbenzenesulfonate solution were mixed and added to 5 parts of lanthanum chloride solution, followed by adding 2 parts of zirconium oxide and stirring thoroughly to obtain a modified solution; S2: The modified cerium solution and the additive are mixed in a weight ratio of 5:3 and ball-milled at a ball-milling speed of 1000 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a rare earth-doped modified additive.

[0036] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 2%; the mass fraction of the lanthanum chloride solution is 4%.

[0037] The stirring speed of the stirring modification treatment in this embodiment is 450 r / min, and the stirring is carried out for 20 minutes.

[0038] The preparation method of the additive of this embodiment is: S11: Silicon carbide, sodium silicate solution and dopamine hydrochloride solution are mixed in a weight ratio of 3:2:5 to obtain silicon carbide liquid; S12: 3 parts of yttrium oxide, 2 parts of scandium and 5 parts of silicon carbide liquid are mixed and ultrasonically treated. After the ultrasonic treatment is completed, the mixture is filtered and dried to obtain an additive.

[0039] The mass fraction of the sodium silicate solution is 2%; the mass fraction of the dopamine hydrochloride solution is 4%; the ultrasonic power of the blending ultrasonic treatment is 350W, and the ultrasonic treatment lasts for 20 minutes.

[0040] The method for preparing a conductive silver paste for LTCC hole filling of this embodiment includes the following steps: The organic resin and the organic solvent are mixed, heated and stirred, and then filtered under positive pressure to obtain the desired organic carrier; The organic additive, the organic carrier, the inorganic additive, the organic particles, the conductive silver powder and the organic solvent are uniformly mixed to obtain a premix; The premix is ​​fully dispersed by a three-roll mill grinding and dispersion method to obtain a pre-finished product, and then the premix is ​​filtered and homogenized under positive pressure to obtain the conductive silver paste for LTCC hole filling.

[0041] The electric heating temperature of the hot melt stirring in this embodiment is 70° C., the stirring speed is set to 200 RPM, and the heating stirring time is 12 hours.

[0042] The premix was dispersed 8 times in a three-roll mill, with the roller spacing decreasing from large to small, and the viscosity control range was 1200 Kcps.

[0043] Example 2. The conductive silver paste for LTCC hole filling of this embodiment includes the following raw materials in percentage by weight: 92% conductive silver powder, 9% organic solvent, 4% organic particles, 3% organic resin, 2% organic additives, and 1% inorganic additives.

[0044] In this embodiment, the organic solvent includes alcohols, the organic resin includes ethyl cellulose, and the organic additives include a dispersant, a leveling agent, a plasticizer, and a coupling agent, wherein the dispersant, the leveling agent, the plasticizer, and the coupling agent are compounded in a weight ratio of 1:1:1:1. In this embodiment, the alcohol is ethanol; the ether is diethylene glycol dimethyl ether; the organic particles are polymethyl methacrylate microspheres; the dispersant is polyether phosphate; the coupling agent is silane coupling agent KH560; the plasticizer is tributyl citrate; and the leveling agent is an organic silicone leveling agent.

[0045] The inorganic additive of this embodiment is a rare earth-doped modified additive, and the specific preparation method is as follows: S1: The rare earth cerium was heat treated at 130°C for 10 min, then heated to 220°C at a rate of 4°C / min, kept at this temperature for 5 min, and finally cooled to room temperature in air; Immerse the cerium cooled to room temperature in a modification solution 5 times the total amount of cerium, stirring and modifying the solution, stirring until the solution is modified, and obtain a modified cerium solution; The preparation method of the modified liquid is: 3 parts of silane coupling agent KH550 and 3 parts of sodium dodecylbenzenesulfonate solution were blended and added to 8 parts of lanthanum chloride solution, followed by adding 4 parts of zirconium oxide and stirring thoroughly to obtain a modified solution; S2: The modified cerium solution and the additive are mixed in a weight ratio of 5:3 and ball-milled at a ball-milling speed of 1000 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a rare earth-doped modified additive.

[0046] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 5%; the mass fraction of the lanthanum chloride solution is 7%.

[0047] The stirring speed of the stirring modification treatment in this embodiment is 500 r / min, and the stirring is carried out for 30 minutes.

[0048] The preparation method of the additive of this embodiment is: S11: Silicon carbide, sodium silicate solution and dopamine hydrochloride solution are mixed in a weight ratio of 3:2:5 to obtain silicon carbide liquid; S12: 5 parts of yttrium oxide, 4 parts of scandium and 8 parts of silicon carbide liquid are mixed and ultrasonically treated. After the ultrasonic treatment is completed, the mixture is filtered and dried to obtain an additive.

[0049] The mass fraction of the sodium silicate solution is 5%; the mass fraction of the dopamine hydrochloride solution is 7%; the ultrasonic power of the blending ultrasonic treatment is 400W, and the ultrasonic treatment lasts for 20 minutes.

[0050] The method for preparing a conductive silver paste for LTCC hole filling of this embodiment includes the following steps: The organic resin and the organic solvent are mixed, heated and stirred, and then filtered under positive pressure to obtain the desired organic carrier; The organic additive, the organic carrier, the inorganic additive, the organic particles, the conductive silver powder and the organic solvent are uniformly mixed to obtain a premix; The premix is ​​fully dispersed by a three-roll mill grinding and dispersion method to obtain a pre-finished product, and then the premix is ​​filtered and homogenized under positive pressure to obtain the conductive silver paste for LTCC hole filling.

[0051] In this embodiment, the electric heating temperature of the hot melt stirring is 90° C., the stirring speed is set to 400 RPM, and the heating stirring time is 24 hours.

[0052] The premix was dispersed 12 times in a three-roll mill, with the roller spacing decreasing from large to small, and the viscosity control range was 2500 Kcps.

[0053] Example 3. The conductive silver paste for LTCC hole filling of this embodiment includes the following raw materials in percentage by weight: 90% conductive silver powder, 7% organic solvent, 2% organic particles, 1.5% organic resin, 1% organic additives, and 0.5% inorganic additives.

[0054] In this embodiment, the organic solvent includes alcohols, the organic resin includes ethyl cellulose, and the organic additives include a dispersant, a leveling agent, a plasticizer, and a coupling agent, wherein the dispersant, the leveling agent, the plasticizer, and the coupling agent are compounded in a weight ratio of 1:1:1:1. In this embodiment, the alcohol is ethanol; the ether is diethylene glycol dimethyl ether; the organic particles are polymethyl methacrylate microspheres; the dispersant is polyether phosphate; the coupling agent is silane coupling agent KH560; the plasticizer is tributyl citrate; and the leveling agent is an organic silicone leveling agent.

[0055] The inorganic additive of this embodiment is a rare earth-doped modified additive, and the specific preparation method is as follows: S1: The rare earth cerium was heat treated at 120°C for 10 min, then heated to 220°C at a rate of 3°C / min, kept at this temperature for 5 min, and finally air-cooled to room temperature; Immerse the cerium cooled to room temperature in a modification solution 4 times the total amount of cerium, stirring and modifying the solution, stirring until the solution is modified, and obtain the modified cerium solution; The preparation method of the modified liquid is: 2.5 parts of silane coupling agent KH550 and 2 parts of sodium dodecylbenzenesulfonate solution were blended and added to 6.5 parts of lanthanum chloride solution, followed by adding 3 parts of zirconium oxide and stirring thoroughly to obtain a modified solution; S2: The modified cerium solution and the additive are mixed in a weight ratio of 5:3 and ball-milled at a ball-milling speed of 1000 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a rare earth-doped modified additive.

[0056] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 3.5%; the mass fraction of the lanthanum chloride solution is 5.5%.

[0057] The stirring speed of the stirring modification treatment in this embodiment is 470 r / min, and the stirring is carried out for 25 minutes.

[0058] The preparation method of the additive of this embodiment is: S11: Silicon carbide, sodium silicate solution and dopamine hydrochloride solution are mixed in a weight ratio of 3:2:5 to obtain silicon carbide liquid; S12: 4 parts of yttrium oxide, 3 parts of scandium and 6.5 parts of silicon carbide liquid are mixed and ultrasonically treated. After the ultrasonic treatment is completed, the mixture is filtered and dried to obtain an additive.

[0059] The mass fraction of the sodium silicate solution is 3.5%; the mass fraction of the dopamine hydrochloride solution is 5.5%; the ultrasonic power of the blending ultrasonic treatment is 375W, and the ultrasonic treatment lasts for 20 minutes.

[0060] The method for preparing a conductive silver paste for LTCC hole filling of this embodiment includes the following steps: The organic resin and the organic solvent are mixed, heated and stirred, and then filtered under positive pressure to obtain the desired organic carrier; The organic additive, the organic carrier, the inorganic additive, the organic particles, the conductive silver powder and the organic solvent are uniformly mixed to obtain a premix; The premix is ​​fully dispersed by a three-roll mill grinding and dispersion method to obtain a pre-finished product, and then the premix is ​​filtered and homogenized under positive pressure to obtain the conductive silver paste for LTCC hole filling.

[0061] In this embodiment, the electric heating temperature of the hot melt stirring is 80° C., the stirring speed is set to 300 RPM, and the heating stirring time is 18 hours.

[0062] The premix was dispersed 10 times in a three-roll mill with the roller spacing decreasing from large to small. The viscosity was controlled within the range of 1750 Kcps.

[0063] Product performance testing of Examples 1-3;

[0064] Resistivity performance test of Examples 1-3: Comparative Example 1 is different from Example 3 only in that the doped graphene-modified whisker agent is not added.

[0065] Comparative Example 2 is different from Example 3 only in that no modifying liquid is added.

[0066] Comparative Example 3 is different from Example 3 only in that no whisker material is added.

[0067]

[0068] The conductivity effects of Examples 1-3 are significant, while the conductivity of Comparative Examples 1-3 has an obvious tendency to deteriorate.

[0069] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0070] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A conductive silver paste for LTCC hole filling, characterized in that: The composition comprises the following raw materials in weight percentage: 82~92% conductive silver powder, 5~9% organic solvent, 0.5~4% organic particles, 0.5~3% organic resin, 0.3~2% organic additives, 0.01~1% inorganic additives.

2. The conductive silver paste for LTCC hole filling according to claim 1, characterized in that: The organic solvent includes one or more of alcohols or ethers, the organic resin includes one or more of ethyl cellulose, cellulose acetate, and acrylic resin, and the organic additive includes one or more of a dispersant, a leveling agent, a plasticizer, and a coupling agent.

3. The conductive silver paste for LTCC hole filling according to claim 2, characterized in that: The alcohol is ethanol; the ether is diethylene glycol dimethyl ether; the organic microparticles are polymethyl methacrylate microspheres; the dispersant is polyether phosphate; the coupling agent is silane coupling agent KH560; the plasticizer is tributyl citrate; and the leveling agent is an organic silicone leveling agent.

4. The conductive silver paste for LTCC hole filling according to claim 1, characterized in that: The inorganic additive is a rare earth-doped modified additive, and the specific preparation method is as follows: S1: heat-treat rare earth cerium at 110-130°C for 10 min, then heat to 220°C at a rate of 2-4°C / min, hold for 5 min, and finally air-cool to room temperature; Immerse the cerium cooled to room temperature in a modification solution 3-5 times the total amount of cerium, stirring and modifying the solution, stirring until the solution is modified to obtain a modified cerium solution; The preparation method of the modified liquid is: Blend 2-3 parts of silane coupling agent KH550 and 1-3 parts of sodium dodecylbenzenesulfonate solution into 5-8 parts of lanthanum chloride solution, then add 2-4 parts of zirconium oxide, stir thoroughly, and obtain a modified solution; S2: The modified cerium solution and the additive are mixed in a weight ratio of 5:3 and ball-milled at a ball-milling speed of 1000 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a rare earth-doped modified additive.

5. The conductive silver paste for LTCC hole filling according to claim 4, characterized in that: The mass fraction of the sodium dodecylbenzenesulfonate solution is 2-5%; the mass fraction of the lanthanum chloride solution is 4-7%.

6. The conductive silver paste for LTCC hole filling according to claim 4, characterized in that: The stirring speed of the stirring modification treatment is 450-500 r / min, and the stirring is performed for 20-30 minutes.

7. The conductive silver paste for LTCC hole filling according to claim 4, characterized in that: The preparation method of the additive is: S11: Silicon carbide, sodium silicate solution and dopamine hydrochloride solution are mixed in a weight ratio of 3:2:5 to obtain silicon carbide liquid; S12: 3-5 parts of yttrium oxide, 2-4 parts of scandium and 5-8 parts of silicon carbide liquid are mixed and ultrasonically treated. After the ultrasonic treatment is completed, the mixture is filtered and dried to obtain an additive.

8. The conductive silver paste for LTCC hole filling according to claim 7, characterized in that: The mass fraction of the sodium silicate solution is 2-5%; the mass fraction of the dopamine hydrochloride solution is 4-7%; the ultrasonic power of the blending ultrasonic treatment is 350-400W, and the ultrasonic treatment lasts for 20 minutes.

9. A method for preparing a conductive silver paste for LTCC hole filling, characterized in that: The following steps are involved: The organic resin and the organic solvent are mixed, heated and stirred, and then filtered under positive pressure to obtain the desired organic carrier; The organic additive, the organic carrier, the inorganic additive, the organic particles, the conductive silver powder and the organic solvent are uniformly mixed to obtain a premix; The premix is ​​fully dispersed by a three-roll mill grinding and dispersion method to obtain a pre-finished product, and then the premix is ​​filtered and homogenized under positive pressure to obtain the conductive silver paste for LTCC hole filling.

10. The method for preparing a conductive silver paste for LTCC hole filling according to claim 9, characterized in that: The electric heating temperature for hot melt stirring is 70~90℃, the stirring speed is set to 200~400RPM, and the heating stirring time is 12~24 hours; The premix is ​​dispersed 8 to 12 times in a three-roll mill, with the roller spacing decreasing gradually from large to small, and the viscosity control range is 1200 to 2500 Kcps.

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