Copper paste for ceramic antenna, ceramic antenna and preparation method of ceramic antenna

Abstract

The invention provides copper paste for a ceramic antenna, the ceramic antenna and a preparation method of the ceramic antenna, and belongs to the field of electronic paste. The copper paste is composed of spherical low-impurity copper powder, bismuth-boron-silicon lead-free glass powder containing a heavy element combination A and a rare earth element B and a composite organic solvent, the glass powder is prepared through step-by-step pre-firing, the copper paste is prepared through infiltration and mixing, and then the ceramic antenna is prepared through screen printing and nitrogen atmosphere metallization. Through copper powder characteristic optimization, glass powder functional design, organic solvent compounding and precise process regulation and control, the problems that existing silver paste is high in cost and silver migration, and existing copper paste is high in resistivity, poor in binding force and poor in printing performance are solved. The prepared metal copper layer is low in square resistance, the binding force of the ceramic body and the copper metal layer is improved, the cost is greatly reduced compared with that of traditional silver paste, and the silver paste is suitable for ceramic antenna production in the fields of consumption, communication, automobiles and the like and has remarkable industrial application value.

Description

Technical Field

[0001] This invention relates to the technical field of electronic pastes, and more specifically, to a copper paste for ceramic antennas, a ceramic antenna, and a method for preparing the same. Background Technology

[0002] With the rapid penetration of the electronics and information industry into consumer electronics, communications, and automotive sectors, ceramic antennas, as core electronic components, are seeing their application scenarios continuously expand, placing higher demands on the performance and cost of electrode pastes. Currently, silver paste is the mainstream electrode paste for ceramic antennas, but it has two major drawbacks: first, silver is a precious metal, and its continuously soaring price leads to high antenna production costs; second, silver migration is a common phenomenon, seriously affecting the electrical stability and lifespan of ceramic antennas.

[0003] Copper, a metallic material with conductivity comparable to silver but priced at only one-twentieth the cost, and without the risk of ion migration, is an ideal alternative to silver paste. However, there are very few reports on copper paste suitable for ceramic antenna applications in the current technology. Existing copper paste products face multiple technical bottlenecks: high resistivity after metallization, resulting in insufficient conductivity; poor bonding between the metal electrode and the ceramic substrate (ceramic body), leading to poor pull-out force and low antenna reliability; and issues such as non-leveling and cracking during screen printing, directly affecting the electrical performance of subsequent metallization. These shortcomings make it difficult for copper paste to achieve large-scale replacement of silver paste, limiting cost reduction, efficiency improvement, and technological upgrading in the ceramic antenna industry.

[0004] In view of this, the applicant hereby submits this application after studying the existing technology. Summary of the Invention

[0005] This invention provides a copper paste for ceramic antennas, a ceramic antenna, and a method for preparing the same, aiming to improve at least one of the above-mentioned technical problems.

[0006] To address the aforementioned technical problems, this invention provides a copper paste for ceramic antennas, composed of copper powder, glass powder, and an organic solvent. The copper powder is a spherical powder with a particle size D50 of 0.5-3.0 μm, a D90 of 4.0-6.0 μm, an oxygen content of less than 0.3%, a carbon content of less than 0.12%, and an iron impurity content of less than 100 ppm. The glass powder is a bismuth borosilicate lead-free glass system, comprising, by mass percentage: 30-60% bismuth, 20-40% boron, 8-15% silicon, 5-10% aluminum, 6-13% zinc, 0.5-6% heavy element combination A, and 0.1-2% rare earth element B, wherein the heavy element combination A is selected from one or more of titanium, strontium, and barium.

[0007] As a further optimization, the organic solvent is a mixture of terpineol, butyl carbitol, butyl carbitol alkyd, castor oil, and acrylic resin, wherein the mass ratio of terpineol, butyl carbitol, and butyl carbitol alkyd is (1.5-3.0):(0.8-1.0):(0.5-1.2); the viscosity of the organic solvent at 25°C is 10 to 100 Pa·s, and the carbon residue after pyrolysis at 600°C under a reducing atmosphere is less than 1.2%.

[0008] As a further optimization, the rare earth element B is selected from one or more of samarium, praseodymium, neodymium, and cerium.

[0009] As a further optimization, the glass powder has a particle size D50 of 0.5-2.0 μm, a glass transition temperature of 430°C to 480°C, and a softening temperature of 510°C to 540°C.

[0010] The present invention also provides a method for preparing copper paste for ceramic antennas as described above, comprising the following steps: S1: By weight, take 50-85 parts copper powder, 3-20 parts glass powder and the balance organic solvent, mix them and let them stand in a closed space for 12-24 hours, then mix them 5-10 times with a three-roll mill to obtain copper paste with a fineness of 5-30μm and a viscosity of 80-300Pa.s.

[0011] As a further optimization, in step S1, the glass powder is prepared and synthesized through the following steps: S11: Mix the elements of heavy element combination A in proportion and ball mill until D50 is 1.0-3.0μm. After ball milling, the powder is briquetized and pre-calcined at 1000-1100℃. After pre-calcination, it is pulverized to obtain pre-calcined powder A. S12: Mix rare earth element B and ball mill it until D50 is 1.0-3.0μm, then press it into briquettes and pre-calcine it at 450-500℃, and then pulverize it to obtain pre-calcined powder B; S13: Pre-calcined powder A and pre-calcined powder B are mixed with bismuth, boron, silicon, aluminum and zinc in proportion and ball-milled in a planetary ball mill at 300 r / min until D50 is 1.5-2.5 μm. After drying, they are placed in a crucible and melted at 1000-1100℃. The molten liquid is poured into water at 25℃ and cooled to obtain glass frit. S14: The glass frit is crushed and ball-milled until the D50 is 0.5-1.2μm to obtain the glass powder.

[0012] The present invention also provides a method for preparing a ceramic antenna, comprising the following steps: the ceramic antenna prepared by any of the above steps is screen-printed onto the surface of a ceramic substrate with copper paste, dried, and then metallized in a nitrogen atmosphere containing 10-550 ppm oxygen to form a copper layer, the metallization temperature being 550-850℃ and the time being 20-90 minutes, thereby obtaining the ceramic antenna.

[0013] This invention also provides a ceramic antenna, fabricated according to the above-described method, comprising a ceramic body and a copper layer, wherein the sheet resistance of the copper layer is ≤9.0×10⁻⁶. - ³Ω / □, pull-out force ≥15N (1×1mm).

[0014] By adopting the above technical solution, the present invention can achieve the following technical effects: 1. By replacing silver powder with copper powder as the conductive phase, the cost of raw materials is reduced, and the problem of electrical performance degradation caused by silver migration is completely avoided. This achieves the dual advantages of low cost and high stability, solving the core pain point of traditional silver paste.

[0015] 2. By selecting spherical, low-impurity copper powder, designing a narrow particle size distribution, combining the low-carbon residue characteristics of composite organic solvents with a precise metallization process, a metallic copper layer with low sheet resistivity was prepared.

[0016] 3. The glass powder system is innovatively combined with heavy elements and rare earth elements. The heavy elements have a thermal expansion coefficient that matches that of the ceramic body, eliminating thermal stress during the metallization process. The rare earth elements optimize the wettability and bonding activity of the glass powder. Combined with the oxide film removal effect of trace oxygen in the metallization atmosphere, the bonding force between the ceramic body and the copper metal layer is improved, ensuring the structural reliability of the antenna under complex operating conditions.

[0017] 4. By using a composite solvent system of terpineol, butyl carbitol, and butyl carbitol alkyd, and controlling the evaporation rate by a specific ratio, combined with the thixotropic effect of castor oil and acrylic resin, the technical defects of non-leveling and cracking in existing copper paste screen printing are completely solved. The coating after printing is uniform and dense, which provides a key guarantee for the stable performance of subsequent metallization.

[0018] 5. Strong industrial feasibility: The formulation components and process parameters of this application are all adapted to industrial production processes, and the technical solution has high stability and fault tolerance, making it easy to promote and apply on a large scale. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] This invention provides a copper paste for ceramic antennas, which is composed of copper powder, glass powder and organic solvent; the copper powder is spherical powder with a particle size D50 of 0.5-3.0 μm, a D90 of 4.0-6.0 μm, an oxygen content of less than 0.3%, a carbon content of less than 0.12%, and an iron impurity content of less than 100 ppm.

[0021] Specifically, spherical copper powder has a higher packing density and a larger contact area between particles, effectively reducing contact resistance and laying the foundation for forming a low-resistivity metallic copper layer. Simultaneously, limiting the particle size range to D50 of 0.5-3.0 μm and D90 of 4.0-6.0 μm avoids the disruption of conductive pathways caused by fine powder agglomeration, while preventing increased porosity due to coarse powder, ensuring the continuity of the conductive phase. Furthermore, since oxygen forms an insulating copper oxide phase, carbon remains and hinders electron transport, and iron introduces high-resistivity impurities, all three contribute to increased resistivity. Therefore, this invention strictly controls the content of oxygen, carbon, and iron impurities, ensuring the conductivity of the copper paste from the source through low impurity content.

[0022] The glass powder is a bismuth borosilicate lead-free glass system, comprising, by mass percentage: 30-60% bismuth, 20-40% boron, 8-15% silicon, 5-10% aluminum, 6-13% zinc, 0.5-6% heavy element combination A, and 0.1-2% rare earth element B. The heavy element combination A is selected from one or more of titanium, strontium, and barium. The rare earth element B is selected from one or more of samarium, praseodymium, neodymium, and cerium.

[0023] Furthermore, the glass powder has a particle size D50 of 0.5-2.0 μm, a glass transition temperature of 430°C to 480°C, and a softening temperature of 510°C to 540°C.

[0024] Specifically, the bismuth borosilicate lead-free glass system possesses excellent bonding performance and high-temperature stability, avoiding the environmental hazards associated with lead-containing glass. The addition of heavy elements such as titanium, strontium, and barium (A) aims to ensure that the thermal expansion coefficient of the glass powder is comparable to that of the ceramic antenna's ceramic matrix, eliminating internal stress caused by differences in thermal expansion and contraction during metallization, thus solving the problem of insufficient bonding between the copper layer and the ceramic matrix. Rare earth elements such as samarium, praseodymium, neodymium, and cerium (B) refine the glass powder grains, improving its fluidity and wettability after melting, ensuring that the glass powder uniformly coats the copper powder and fills the micropores on the ceramic surface, strengthening interfacial bonding without obstructing conductive pathways. Limiting the glass's transition temperature to 430-480℃ and softening temperature to 510-540℃ is to precisely match the subsequent metallization process temperature of 550-850℃, ensuring that the glass powder melts and flows precisely during metallization, achieving bonding without decomposition or failure.

[0025] The organic solvent is composed of terpineol, butyl carbitol, butyl carbitol alkyd, castor oil and acrylic resin, wherein the mass ratio of terpineol, butyl carbitol and butyl carbitol alkyd is (1.5-3.0):(0.8-1.0):(0.5-1.2), the viscosity of the organic solvent at 25°C is 10 to 100 Pa·s, and the carbon residue after pyrolysis at 600°C under a reducing atmosphere is less than 1.2%.

[0026] Specifically, this invention employs a multi-component composite solvent system. Terpineol, butyl carbitol, and butyl carbitol alkydate have different evaporation rates; mixing them in a specific ratio achieves synergistic evaporation rates, avoiding the problems of cracking in the screen printing coating due to excessively rapid evaporation of a single solvent or sagging due to excessively slow evaporation. Castor oil and acrylic resin, acting as thixotropic agents, enhance the thixotropy of the copper paste, enabling it to remain in a gel-like state when stationary, flow under pressure, and return to a gel-like state after printing, preventing the diffusion and deformation of the printed pattern and solving the problem of non-leveling in existing copper paste screen printing. Limiting the organic solvent viscosity to 10-100 Pa·s is for synergy with copper powder and glass powder, ultimately achieving a copper paste viscosity within the screen printing adaptability range of 80-300 Pa·s, ensuring smooth printing. Simultaneously, the design of <1.2% low carbon residue under a reducing atmosphere avoids the reaction of carbon residue with copper powder and glass powder during metallization, or the formation of an insulating phase, ensuring the conductivity and bonding stability of the metallic copper layer.

[0027] This invention also provides a method for preparing copper paste for ceramic antennas, comprising the following steps: S11: Mix the elements of heavy element combination A in proportion and ball mill until D50 is 1.0-3.0μm. After ball milling, the powder is briquetized and pre-calcined at 1000-1100℃. After pre-calcination, it is pulverized to obtain pre-calcined powder A. S12: Mix rare earth element B and ball mill until D50 is 1.0-3.0μm, press into briquettes, pre-calcine at 450-500℃, and pulverize to obtain pre-calcine powder B; S13: Pre-calcined powder A, pre-calcined powder B, bismuth, boron, silicon, aluminum, and zinc are mixed and ball-milled in a planetary ball mill at 300 r / min according to the above proportions until D50 is 1.5-2.5 μm. After drying, the mixture is placed in a crucible and melted at 1000-1100℃. The molten liquid is then poured into water at 25℃ to cool and obtain a glass frit. S14: The glass frit is crushed and ball-milled until the D50 is 0.5-1.2μm to obtain glass powder.

[0028] In step S11, the heavy element combination A is pre-fired at a high temperature of 1000-1100℃ to remove impurities and moisture, stabilize the element valence state, and avoid the glass powder performance being affected by composition fluctuations during subsequent melting. In step S12, the rare earth element B is pre-fired at a medium temperature of 450-500℃ to remove impurities and avoid the loss of content caused by the high-temperature volatilization of rare earth elements, ensuring that the functions of the two functional elements are effectively exerted. Meanwhile, stepwise ball milling to D50=1.0-3.0μm ensures that the heavy element combination A and rare earth element B are mixed evenly, avoiding local component enrichment. The planetary ball mill speed of 300r / min and the parameters of ball milling to D50=1.5-2.5μm enable the uniform dispersion of pre-calcined powders A and B with basic elements such as bismuth and boron, ensuring the consistency of glass powder composition. Finally, crushing and ball milling to D50=0.5-1.2μm ensures that the glass powder can uniformly coat the surface of copper powder and melt and flow rapidly during metallization, avoiding poor adhesion or obstruction of conductive paths caused by excessively large glass powder particles.

[0029] Furthermore, step S1 is included: by weight, take 50-85 parts copper powder, 3-20 parts glass powder, and the remaining organic solvent, mix them, and let them stand and soak in a sealed space for 12-24 hours. Then, mix them 5-10 times with a three-roll mill to obtain a copper paste with a fineness of 5-30 μm and a viscosity of 80-300 Pa·s. This process ensures that the conductive phase dominates in the copper paste, reducing the influence of glass powder (insulating phase) on conductivity. Simultaneously, it provides sufficient bonding sites while avoiding excessively thick or brittle bonding layers due to excessive glass powder, thus achieving a balance between conductivity and bonding strength. The remaining organic solvent can be flexibly adjusted according to the amount of copper powder and glass powder used to ensure the dispersibility and viscosity compatibility of the paste. The process involves allowing the organic solvent to fully penetrate and coat the copper and glass powder particles in a sealed environment for 12-24 hours, breaking down the agglomeration between the powder particles and laying the foundation for subsequent uniform mixing. A three-roll mill is then used to mix the powder 5-10 times, further dispersing any remaining agglomerates using shear force to ensure uniform dispersion of the three components. Controlling the fineness to 5-30μm avoids large impurities in the paste that could cause printing defects. The viscosity parameter of 80-300Pa.s is precisely matched to the screen printing process, ensuring the copper paste can smoothly pass through the screen and form a uniformly thick, clearly patterned coating on the ceramic surface.

[0030] The present invention also provides a method for preparing a ceramic antenna, wherein the ceramic antenna prepared above is screen-printed onto the surface of a ceramic substrate with copper paste, dried, and then metallized in a nitrogen atmosphere containing 10-550 ppm oxygen to form a copper layer. The metallization temperature is 550-850℃ and the time is 20-90 minutes to obtain the ceramic antenna.

[0031] The drying step removes most of the organic solvents from the slurry, preventing bubbles and cracks caused by rapid solvent evaporation during metallization and ensuring the density of the copper layer. Simultaneously, a nitrogen atmosphere provides an inert environment for metallization, preventing excessive oxidation of the copper powder. Adding trace amounts of oxygen (10-550 ppm) selectively removes trace oxide films from the copper powder and ceramic substrate surfaces. These oxide films hinder the sintering bonding between copper powder particles and the adhesion between glass powder and the substrate; the trace oxygen eliminates this obstacle while preventing secondary oxidation of the copper powder due to excessive oxygen. Furthermore, the temperature range of 550-850℃ matches the softening temperature of glass powder (510-540℃), ensuring that the glass powder melts and flows fully, achieving a strong bond between the copper powder and the ceramic matrix. At the same time, this temperature promotes the appropriate sintering of copper powder particles, forming a dense metallic copper layer and reducing resistivity. Sufficient metallization time ensures that the processes of oxide film removal, glass powder melting, and copper powder sintering are fully carried out, avoiding insufficient bonding or excessively high resistivity due to too short a time, and also avoiding excessive growth of copper powder grains due to too long a time, which would lead to increased grain boundary defects, increased resistivity, or damage to the ceramic matrix.

[0032] The present invention also provides a ceramic antenna, manufactured according to the above-described method, comprising a ceramic body and a copper layer, wherein the sheet resistance of the copper layer is ≤9.0×10⁻⁶. - ³Ω / □, pull-out force ≥15N (1×1mm).

[0033] Example 1 (1) Take heavy element combination A (titanium: strontium: barium = 1:1:1) and mix them in proportion. Ball mill to D50 = 2.0 μm. After pressing into blocks, pre-calcine at 1050℃ and pulverize to obtain pre-calcine powder A. Take rare earth element B (samarium) and mix and ball mill to D50 = 2.0 μm. After pressing into blocks, pre-calcine at 480℃ and pulverize to obtain pre-calcine powder B. By mass percentage, take 45% bismuth, 30% boron, 10% silicon, 7% aluminum, 6% zinc, 1.5% pre-calcine powder A and 0.5% pre-calcine powder B. Mix and ball mill them in a planetary ball mill at 300 r / min to D50 = 2.0 μm. After drying, put them into a crucible and melt them at 1050℃. Pour the melt into water at 25℃ and cool to obtain glass frit. Break the glass frit and ball mill it to D50 = 0.8 μm to obtain glass powder.

[0034] (2) By mass, take 70 parts of spherical copper powder (D50=1.5μm, D90=5.0μm, oxygen content 0.2%, carbon content 0.1%, iron content 80ppm), 15 parts of the above glass powder, and 15 parts of organic solvent (terpineol: butyl carbitol: butyl carbitol ester = 2.0:0.9:0.8, with appropriate amounts of castor oil and acrylic resin added, viscosity 50Pa.s at 25℃, carbon residue 0.8% at 600℃ in a reducing atmosphere), mix them, let them stand and soak in a closed space for 18 hours, and mix them 5 times with a three-roll mill to obtain a copper paste with a fineness of 10μm and a viscosity of 200Pa.s.

[0035] (3) The copper paste is screen-printed onto the surface of the ceramic substrate, dried, and then metallized at 600°C for 50 minutes in a nitrogen atmosphere containing 100ppm oxygen to obtain a ceramic antenna.

[0036] (4) The sheet resistance of the copper layer was tested to be 5.5 × 10⁻⁶. - ³Ω / □, with a pull-out force of 15N (1×1mm).

[0037] Example 2 (1) Take heavy element combination A (titanium: strontium = 1:1) and mix them in proportion. Ball mill to D50 = 1.5 μm. After pressing into blocks, pre-calcine at 1080℃ and pulverize to obtain pre-calcine powder A. Take rare earth element B (praseodymium) and mix and ball mill to D50 = 1.5 μm. After pressing into blocks, pre-calcine at 490℃ and pulverize to obtain pre-calcine powder B. By mass percentage, take 50% bismuth, 28% boron, 9% silicon, 6% aluminum, 5% zinc, 2.0% pre-calcine powder A and 0.8% pre-calcine powder B. Mix and ball mill in a planetary ball mill at 300 r / min to D50 = 1.8 μm. After drying, put it into a crucible and melt it at 1080℃. Pour the melt into water at 25℃ and cool to obtain glass frit. Break the glass frit and ball mill to D50 = 0.6 μm to obtain glass powder.

[0038] (2) By mass, take 80 parts of spherical copper powder (D50=1.0μm, D90=4.5μm, oxygen content 0.15%, carbon content 0.08%, iron content 70ppm), 10 parts of the above glass powder, and 10 parts of organic solvent (terpineol: butyl carbitol: butyl carbitol ester = 2.5:0.8:0.7, with appropriate amounts of castor oil and acrylic resin added, viscosity 60Pa.s at 25℃, carbon residue 0.7% at 600℃ in a reducing atmosphere), mix them, let them stand and soak in a closed space for 20 hours, and mix them 5 times with a three-roll mill to obtain a copper paste with a fineness of 6μm and a viscosity of 250Pa.s.

[0039] (3) The copper paste is screen-printed onto the surface of the ceramic substrate, dried, and then metallized at 590°C for 50 minutes in a nitrogen atmosphere containing 100ppm oxygen to obtain a ceramic antenna.

[0040] (4) The sheet resistance of the copper layer was tested to be 5.0 × 10⁻⁶. - ³Ω / □, with a pull-out force of 18N (1×1mm).

[0041] Example 3 (1) Take heavy element combination A (strontium:barium = 1:2) and mix them in proportion. Ball mill to D50 = 1.8 μm. After pressing into blocks, pre-calcine at 1060℃ and pulverize to obtain pre-calcine powder A. Take rare earth element B (neodymium:cerium = 1:1) and mix them. Ball mill to D50 = 1.8 μm. After pressing into blocks, pre-calcine at 470℃ and pulverize to obtain pre-calcine powder B. By mass percentage, take 48% bismuth, 29% boron, 11% silicon, 6% aluminum, 5% zinc, 1.9% pre-calcine powder A and 1.2% pre-calcine powder B. Mix and ball mill them in a planetary ball mill at 300 r / min to D50 = 2.2 μm. After drying, put them into a crucible and melt them at 1060℃. Pour the melt into water at 25℃ and cool to obtain glass frit. Break the glass frit and ball mill it to D50 = 0.7 μm to obtain glass powder.

[0042] (2) By mass, take 75 parts of spherical copper powder (D50=0.8μm, D90=4.2μm, oxygen content 0.18%, carbon content 0.09%, iron content 75ppm), 12 parts of the above glass powder, and 13 parts of organic solvent (terpineol: butyl carbitol: butyl carbitol ester = 2.2:0.9:0.9, with appropriate amounts of castor oil and acrylic resin added, viscosity 55Pa.s at 25℃, carbon residue 0.9% at 600℃ in a reducing atmosphere), mix them, let them stand and soak in a closed space for 16 hours, and mix them 6 times with a three-roll mill to obtain a copper paste with a fineness of 8μm and a viscosity of 220Pa.s.

[0043] (3) The copper paste is screen-printed onto the surface of the ceramic substrate, dried, and then metallized at 610°C for 50 minutes in a nitrogen atmosphere containing 150ppm oxygen to obtain a ceramic antenna.

[0044] (4) The sheet resistance of the copper layer was tested to be 8.0 × 10⁻⁶. - ³Ω / □, with a pull-out force of 19N (1×1mm).

[0045] Example 4 (1) Take heavy element combination A (titanium:barium = 2:1) and mix them in proportion. Ball mill to D50 = 2.2 μm. After pressing into blocks, pre-calcine at 1070℃ and pulverize to obtain pre-calcine powder A. Take rare earth element B (samarium:praseodymium = 1:1) and mix and ball mill to D50 = 2.2 μm. After pressing into blocks, pre-calcine at 485℃ and pulverize to obtain pre-calcine powder B. By mass percentage, take 46% bismuth, 31% boron, 10% silicon, 7% aluminum, 4% zinc, 2.3% pre-calcine powder A and 0.9% pre-calcine powder B. Mix and ball mill them in a planetary ball mill at 300 r / min to D50 = 2.1 μm. After drying, put them into a crucible and melt them at 1070℃. Pour the melt into water at 25℃ and cool to obtain glass frit. Break the glass frit and ball mill it to D50 = 0.9 μm to obtain glass powder.

[0046] (2) By mass, take 78 parts of spherical copper powder (D50=1.1μm, D90=4.8μm, oxygen content 0.22%, carbon content 0.11%, iron content 90ppm), 11 parts of the above glass powder, and 11 parts of organic solvent (terpineol: butyl carbitol: butyl carbitol ester = 2.3:0.85:0.6, with appropriate amounts of castor oil and acrylic resin added, viscosity 45Pa.s at 25℃, carbon residue 1.0% at 600℃ in a reducing atmosphere), mix them, let them stand and soak in a closed space for 22 hours, and mix them 7 times with a three-roll mill to obtain a copper paste with a fineness of 9μm and a viscosity of 230Pa.s.

[0047] (3) The copper paste is screen-printed onto the surface of the ceramic substrate, dried, and then metallized at 585°C for 55 minutes in a nitrogen atmosphere containing 200ppm oxygen to obtain a ceramic antenna.

[0048] (4) The sheet resistance of the copper layer was tested to be 5.8 × 10⁻⁶. - ³Ω / □, with a pull-out force of 17N (1×1mm).

[0049] Example 5 (1) Take heavy element combination A (titanium: strontium: barium = 2:1:1) and mix them in proportion. Ball mill to D50 = 1.6 μm. After pressing into blocks, pre-calcine at 1090℃ and pulverize to obtain pre-calcined powder A. Take rare earth element B (cerium: samarium = 1:2) and mix them. Ball mill to D50 = 1.6 μm. After pressing into blocks, pre-calcine at 495℃ and pulverize to obtain pre-calcined powder B. By mass percentage, take 52% bismuth, 27% boron, 10% silicon, 6% aluminum, 5% zinc, 3.2% pre-calcined powder A and 1.6% pre-calcined powder B. Mix and ball mill them in a planetary ball mill at 300 r / min to D50 = 1.7 μm. After drying, put them into a crucible and melt them at 1090℃. Pour the melt into water at 25℃ and cool to obtain glass frit. Break the glass frit and ball mill it to D50 = 0.5 μm to obtain glass powder.

[0050] (2) By mass, take 82 parts of spherical copper powder (D50=0.8μm, D90=4.1μm, oxygen content 0.12%, carbon content 0.07%, iron content 60ppm), 13 parts of the above glass powder, and 5 parts of organic solvent (terpineol: butyl carbitol: butyl carbitol ester = 2.8:0.95:1.1, with appropriate amounts of castor oil and acrylic resin added, viscosity 70Pa.s at 25℃, carbon residue 0.6% at 600℃ in a reducing atmosphere), mix them, let them stand and soak in a closed space for 24 hours, and mix them 8 times with a three-roll mill to obtain a copper paste with a fineness of 7μm and a viscosity of 280Pa.s.

[0051] (3) The copper paste is screen-printed onto the surface of the ceramic substrate, dried, and then metallized at 620°C for 60 minutes in a nitrogen atmosphere containing 250ppm oxygen to obtain a ceramic antenna.

[0052] (4) The sheet resistance of the copper layer was tested to be 4.7 × 10⁻⁶. - ³Ω / □, with a pull-out force of 22N (1×1mm).

[0053] Example 6 (1) Take heavy element combination A (titanium) in proportion, ball mill to D50=2.5μm, press into blocks and pre-calcine at 1040℃, and pulverize to obtain pre-calcined powder A; take rare earth element B (praseodymium:neodymium = 1:1) and ball mill to D50=2.5μm, press into blocks and pre-calcine at 460℃, and pulverize to obtain pre-calcined powder B; take 42% bismuth, 32% boron, 12% silicon, 8% aluminum, 6% zinc, 0.9% pre-calcined powder A and 0.6% pre-calcined powder B by mass percentage, mix and ball mill in a planetary ball mill at 300r / min to D50=2.4μm, dry and put into a crucible and melt at 1040℃, pour the melt into 25℃ water to cool to obtain glass frit; crush the glass frit and ball mill to D50=1.1μm to obtain glass powder.

[0054] (2) By mass, take 65 parts of spherical copper powder (D50=2.0μm, D90=5.8μm, oxygen content 0.28%, carbon content 0.12%, iron content 95ppm), 14 parts of the above glass powder, and 21 parts of organic solvent (terpineol: butyl carbitol: butyl carbitol ester = 1.8:0.8:1.2, with appropriate amounts of castor oil and acrylic resin added, viscosity 30Pa.s at 25℃, carbon residue 1.1% at 600℃ in a reducing atmosphere), mix them, let them stand and soak in a closed space for 12 hours, and mix them 5 times with a three-roll mill to obtain a copper paste with a fineness of 25μm and a viscosity of 180Pa.s.

[0055] (3) The copper paste is screen-printed onto the surface of the ceramic substrate, dried, and then metallized at 570°C for 60 minutes in a nitrogen atmosphere containing 80ppm oxygen to obtain a ceramic antenna.

[0056] (4) The sheet resistance of the copper layer was tested to be 9.0 × 10⁻⁶. - ³Ω / □, with a pull-out force of 17N (1×1mm).

[0057] Comparative Example This comparative example provides a prior art ceramic antenna using conventional bismuth borosilicate glass powder (without the addition of heavy element combination A and rare earth element B). By mass percentage, the powder comprises 45% bismuth, 30% boron, 15% silicon, 5% aluminum, and 5% zinc, ball-milled to a D50 of 1.5 μm, with a glass transition temperature of 450℃ and a softening temperature of 520℃. By mass, 70 parts of irregular copper powder (D50=2.5μm, D90=6.5μm, oxygen content 0.5%, carbon content 0.2%, iron content 150ppm), 15 parts of the aforementioned conventional glass powder, and 15 parts of a single terpineol organic solvent (viscosity 40 Pa·s at 25℃, carbon residue 1.8% at 600℃ reducing atmosphere) are mixed and then directly passed through a three-roll mill five times to obtain a copper paste with a fineness of 35μm and a viscosity of 150 Pa·s. The copper paste was screen-printed onto the surface of a ceramic substrate, dried, and then metallized at 600°C for 50 minutes in a pure nitrogen atmosphere to obtain a ceramic antenna. The sheet resistance of the copper layer was measured to be 55 × 10⁻⁶. - ³Ω / □, with a pull-out force of 7N (1×1mm), and obvious cracking and non-leveling phenomena occurred during the screen printing process.

[0058] Preferably, the sheet resistance of the copper layer of the ceramic antenna provided in Embodiment 5 of the present invention is ≤4.7×10⁻⁶. - ³Ω / □, pull-out force ≥22N (1×1mm). In this embodiment, the content of heavy element A is increased to 3.2%, and the content of rare earth element B is 1.6%, maximizing the synergistic effect of the two and further optimizing the matching degree with the thermal expansion coefficient of the ceramic body. The metallization time is extended to 60 minutes, resulting in a more complete interface reaction and a stable pull-out force of 22N. The copper powder particle size D50=0.8μm and the metallization temperature of 620℃ avoid excessive grain growth. The organic solvent carbon residue is 0.6%, which does not have a significant impact on the conductivity, and the sheet resistance remains at a low level.

[0059] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0060]

[0061] As shown in the table above: In summary, this invention utilizes spherical high-purity copper powder to reduce contact resistance and impurity interference. Combined with a composite organic solvent to minimize carbon residue and prevent the formation of an insulating phase, and precise control of the metallization atmosphere to promote copper powder sintering, a continuous and dense conductive pathway is constructed, resulting in a metallized copper layer with low resistivity. Furthermore, the heavy element A in the glass powder matches the thermal expansion coefficient of the ceramic body to eliminate interfacial stress, while rare earth element B optimizes the wettability of the glass powder to strengthen mechanical and chemical bonding. Combined with the full reaction of the metallization process, a strong bond between the copper layer and the ceramic body is achieved, resolving the problem of poor pull-out force. Finally, the composite organic solvent of this invention, through the synergistic evaporation rates of its multiple components, combined with the thixotropic effects of castor oil and acrylic resin, ensures controllable flow and uniform drying of the paste during printing, thus solving the problem of non-leveling and cracking during printing. Compared to traditional silver paste, the copper paste of this invention has lower costs and eliminates the risk of silver migration. Compared to existing copper pastes, this invention achieves a significant improvement in conductivity, adhesion, and printability, overcoming the technical bottleneck of replacing silver paste with copper paste. The technical solution demonstrates good stability and fault tolerance, meeting the needs of industrial production and providing reliable support for the industrial application of copper paste for ceramic antennas.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A copper paste for ceramic antennas, characterized in that, It is composed of copper powder, glass powder and organic solvent; the copper powder is spherical powder with a particle size D50 of 0.5-3.0μm, D90 of 4.0-6.0μm, oxygen content of less than 0.3%, carbon content of less than 0.12%, and iron impurity content of less than 100ppm; The glass powder is a bismuth borosilicate lead-free glass system, comprising, by mass percentage: 30-60% bismuth, 20-40% boron, 8-15% silicon, 5-10% aluminum, 6-13% zinc, 0.5-6% heavy element combination A and 0.1-2% rare earth element B, wherein the heavy element combination A is selected from one or more of titanium, strontium, and barium.

2. The copper paste for a ceramic antenna according to claim 1, characterized in that... The organic solvent is composed of terpineol, butyl carbitol, butyl carbitol alkyd, castor oil and acrylic resin, wherein the mass ratio of terpineol, butyl carbitol and butyl carbitol alkyd is (1.5-3.0):(0.8-1.0):(0.5-1.2); the viscosity of the organic solvent at 25°C is 10 to 100 Pa·s, and the carbon residue after pyrolysis at 600°C under a reducing atmosphere is less than 1.2%.

3. The copper paste for a ceramic antenna according to claim 1, characterized in that... The rare earth element B is selected from one or more of samarium, praseodymium, neodymium, and cerium.

4. The copper paste for a ceramic antenna according to claim 1, characterized in that... The glass powder has a particle size D50 of 0.5-2.0 μm, a glass transition temperature of 430℃ to 480℃, and a softening temperature of 510℃ to 540℃.

5. A method for preparing copper paste for ceramic antennas as described in any one of claims 1 to 4, characterized in that... This includes the following steps: S1: By weight, take 50-85 parts copper powder, 3-20 parts glass powder and the balance organic solvent, mix them and let them stand in a closed space for 12-24 hours, then mix them 5-10 times with a three-roll mill to obtain copper paste with a fineness of 5-30μm and a viscosity of 80-300Pa.s.

6. The method for preparing copper paste for ceramic antennas according to claim 5, characterized in that... In step S1, the glass powder is prepared and synthesized through the following steps: S11: Mix the elements of heavy element combination A in proportion and ball mill until D50 is 1.0-3.0μm. After ball milling, the powder is briquetized and pre-calcined at 1000-1100℃. After pre-calcination, it is pulverized to obtain pre-calcined powder A. S12: Mix rare earth element B and ball mill it until D50 is 1.0-3.0μm, then press it into briquettes and pre-calcine it at 450-500℃, and then pulverize it to obtain pre-calcined powder B; S13: Pre-calcined powder A and pre-calcined powder B are mixed with bismuth, boron, silicon, aluminum and zinc in proportion and ball-milled in a planetary ball mill at 300 r / min until D50 is 1.5-2.5 μm. After drying, they are placed in a crucible and melted at 1000-1100℃. The molten liquid is poured into water at 25℃ and cooled to obtain glass frit. S14: The glass frit is crushed and ball-milled until the D50 is 0.5-1.2μm to obtain the glass powder.

7. A method for fabricating a ceramic antenna, characterized in that... The process includes the following steps: the ceramic antenna prepared according to any one of claims 5 to 6 is screen-printed onto the surface of a ceramic substrate with copper paste, dried, and then metallized in a nitrogen atmosphere containing 10-550 ppm oxygen to form a copper layer. The metallization temperature is 550-850℃ and the time is 20-90 minutes to obtain the ceramic antenna.

8. A ceramic antenna, characterized in that... The product, prepared according to the method described in claim 7, comprises a ceramic body and a copper layer, wherein the sheet resistance of the copper layer is ≤9.0×10⁻⁶. - ³Ω / □, pull-out force ≥15N (1×1mm).

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