A copper electrode, its fabrication method, and electronic components using the copper electrode.

Abstract

This invention relates to a copper electrode, comprising a copper electrode layer and a protective layer, wherein the protective layer at least covers the top and side surfaces of the copper electrode layer; the ratio of the thickness of the copper electrode layer to the thickness of the protective layer is 1:0.8~1.5, and the protective layer is made of a resin composition. This invention also discloses a method for manufacturing the copper electrode. This invention further discloses an electronic component. By using a protective layer to cover the copper electrode layer, this invention avoids the problem of continuous oxidation of the copper electrode in air, creating conditions for the long-term use of the copper electrode product.

Description

Technical Field

[0001] The invention relates to the field of electronic component technology, and in particular to a copper electrode, a method for manufacturing the same, and electronic components using the copper electrode. Background Technology

[0002] With the increasing demand for low cost, miniaturization, high performance, and high density in electronic products, the electronic component manufacturing industry urgently needs conductive materials that combine excellent performance with cost advantages. Conductive pastes, as the core material for electrode preparation, have traditionally been made from precious metals such as gold and silver. While these pastes possess advantages such as good conductivity and mature processing techniques, their scarcity and high prices due to precious metal resources have led to a significant increase in product cost pressures and a decline in market competitiveness.

[0003] Against this backdrop, copper conductor pastes have emerged as a leading alternative due to their significant price advantage and outstanding performance. Copper's conductivity is comparable to silver, and it possesses superior high-frequency characteristics. It also avoids the electron migration issues associated with silver electrodes, and sintered copper electrodes exhibit excellent solderability and weldability, making it an ideal replacement for precious metal pastes. However, copper's reactive chemical properties and susceptibility to oxidation during production and use severely limit the large-scale application of copper conductor pastes.

[0004] To address the oxidation problem during copper electrode sintering, existing technologies have attempted air sintering, such as the self-promoting antioxidant copper electrode preparation method disclosed in patent CN111489865A. This method involves sequentially printing an oil seal layer and a self-promoting layer on the surface of a copper printed layer, utilizing the protective layer formed by the reaction of the two materials during sintering to isolate the electrode from air. However, this approach has a key drawback: during the high-temperature sintering of the three layers, the high-temperature grease in the oil seal layer and the oxides and solvents in the self-promoting layer can easily penetrate into the interior of the copper printed layer, damaging the electrode's microstructure, introducing impurities or forming an interface layer on the copper electrode surface, potentially increasing contact resistance and affecting product performance.

[0005] Furthermore, even if oxidation during the sintering process is mitigated, copper electrodes will continue to oxidize when exposed to air during subsequent use, eventually leading to electrode failure. Therefore, developing a copper electrode and its manufacturing method that can prevent component penetration during the preparation process and achieve long-term oxidation resistance has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] One of the purposes of this invention is to provide a copper electrode that solves the problem of copper electrodes being easily oxidized during long-term use;

[0007] A second objective of this invention is to provide a method for preparing the aforementioned electrode. A third objective of this invention is to provide electronic components employing the aforementioned electrodes.

[0008] To achieve the above objectives, the present invention discloses a copper electrode, comprising a copper electrode layer and a protective layer, wherein the protective layer covers at least the top and side surfaces of the copper electrode layer; the ratio of the thickness of the copper electrode layer to the thickness of the protective layer is 1:0.8~1.5, the thickness of the copper electrode layer is 5-15 μm, the thickness of the protective layer is 5-25 μm, and the protective layer is made of a resin composition.

[0009] Preferably, the resin composition comprises, by weight percentage: 20-50% epoxy resin, 10-20% silicone resin, 10-30% saturated resin, and 2-10% curing agent, wherein the curing agent is an amine curing agent.

[0010] Preferably, the protective layer is provided with clearance holes.

[0011] Preferably, a pin is welded onto the copper electrode layer, with one end of the pin fixed to the copper electrode layer and the other end extending through the protective layer.

[0012] Preferably, the copper electrode layer has a thickness of 10 μm, and the protective layer has a thickness of 10 μm.

[0013] The present invention also includes a method for preparing the above-mentioned copper electrode, a method for manufacturing a copper electrode, wherein the copper electrode is printed on a substrate, comprising the following steps: S1. Using screen printing technology, print copper paste onto the substrate. The mesh size of the screen is 200-400 mesh. S2. Dry the copper paste at 80-150℃ for 5-10 minutes. S3. Sinter the copper electrode layer in an inert gas atmosphere at 600-850℃ for 5-10 minutes. S4. Print a protective paste onto the copper electrode layer using screen printing technology. S5. Cure the protective paste to form a protective layer on the surface of the copper electrode layer, thus obtaining the copper electrode.

[0014] Preferably, the copper paste composition, by percentage by mass, includes the following components: 50-80% copper powder, 3-10% inorganic ceramic additives, 10-20% organic solvent, and 0.1-5% polymer resin.

[0015] Preferably, the protective slurry composition, by percentage by mass, includes the following components: 20-50% epoxy resin, 10-20% silicone resin, 10-30% saturated resin, and 2-10% curing agent.

[0016] Preferably, the protective slurry further includes an organic solvent; the organic solvent is selected from at least one of ethanol, ethyl acetate, and propylene glycol methyl ether, and the amount used is 10-20% by weight percentage, and the organic solvent completely evaporates during the heating curing or UV curing process, leaving no residue in the final protective layer.

[0017] Preferably, the protective slurry is cured by heat curing or UV curing, wherein the heat curing conditions are 100~150℃ for 10~30min, and the UV curing conditions are irradiation with a 100W UV lamp for 2~5 seconds.

[0018] Preferably, the mesh count of the screen is 250, and the protective layer is provided with clearance holes. In step S4, when printing the protective paste, the screen corresponding to the clearance hole is set to a meshless structure.

[0019] The present invention also discloses an electronic component, comprising a substrate and the copper electrode, wherein the copper electrode is printed on the substrate; or comprising a substrate and a copper electrode manufactured using the method described above, wherein at least one copper electrode is provided on the substrate.

[0020] Preferably, the electronic components are antennas, capacitors, LTCCs, chip resistors, sensors, or filters, and the substrate is ceramic.

[0021] The invention has the following beneficial effects: 1. By using a protective layer to cover the copper electrode layer, this invention avoids the problem of continuous oxidation of the copper electrode in the air, creating conditions for the long-term use of copper electrode products.

[0022] 2. The copper electrode layer and the protective layer are cured and molded separately to ensure that the copper electrode completes the densification of its microstructure and grain growth in an inert atmosphere, thereby obtaining the best intrinsic conductivity. The protective layer applied afterward is a physical cover, and as long as the thickness is appropriate and the insulation is good, it has minimal impact on the bulk resistance of the electrode.

[0023] 3. Replacing silver electrodes with copper electrodes significantly reduces material costs without changing performance.

[0024] 4. Excellent weather resistance broadens application scenarios. The hybrid protective layer combines the chemical stability of epoxy resin with the high and low temperature resistance and UV resistance of silicone resin. It can work stably in a wide temperature range of -40℃ to 125℃ and can resist the corrosion of complex environments such as damp heat, salt spray, and ultraviolet rays. It is suitable for outdoor and high temperature and high humidity conditions, thus broadening the application boundaries of copper electrodes. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure provided in a specific embodiment of the invention.

[0026] Figure 2 This is a schematic diagram of the clearance hole provided in a specific embodiment of the invention.

[0027] Figure 3 This is a schematic diagram of the pin structure provided in a specific embodiment of the invention.

[0028] Figure 4 This is a comparison diagram of the VSWR of the copper electrode and the silver electrode provided in a specific embodiment of the invention.

[0029] Figure 5 This is a comparison chart of the efficiency of copper and silver electrodes provided in a specific embodiment of the invention.

[0030] Figure 6 This is a gain comparison diagram of the copper electrode and the silver electrode provided in a specific embodiment of the invention.

[0031] Figure 7 This is a 200x magnified view of the sintered appearance of the copper electrode provided in a specific embodiment of the invention.

[0032] Figure 8 This is a 200x magnified view of the sintered appearance of the silver electrode provided in a specific embodiment of the invention.

[0033] Figure 9 This is a 1000x magnified view of the sintered appearance of the copper electrode provided in a specific embodiment of the invention.

[0034] Figure 10 This is a 1000x magnified view of the sintered appearance of the silver electrode provided in a specific embodiment of the invention.

[0035] Figure 11 This is a schematic diagram showing the thickness of the copper electrode provided in a specific embodiment of the invention.

[0036] Figure 12 This is a schematic diagram showing the thickness of the silver electrode provided in a specific embodiment of the invention.

[0037] Explanation of symbols for main components: 1. Substrate; 2. Copper electrode layer; 21. Lead; 3. Protective layer; 31. Clearance hole. Detailed Implementation

[0038] To make the purpose, technical solution, and advantages of the invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] Example 1 like Figure 1 The present invention provides a copper electrode, comprising a copper electrode layer 2 and a protective layer 3, wherein the protective layer 3 covers at least the top surface and the side surface of the copper electrode layer 2; the ratio of the thickness of the copper electrode layer 2 to the thickness of the protective layer 3 is 1:0.8~1.5, the thickness of the copper electrode layer 2 is 5-15μm, the thickness of the protective layer 3 is 5-25μm, and the protective layer 3 is made of a resin composition.

[0040] The copper electrode layer 2 has a thickness of 10 μm and is prepared using copper powder with a particle size of less than 1 μm. Copper powder with this particle size has a large specific surface area, which can form a dense electrode structure after sintering, ensuring high conductivity of the electrode. The copper electrode layer 2 is fixed to the surface of the ceramic substrate 1 by screen printing. The electrode pattern is designed according to the conductivity requirements of the actual electronic components.

[0041] The resin composition comprises, by weight percentage: 20-50% epoxy resin, 10-20% silicone resin, 10-30% saturated resin, and 2-10% curing agent, which is an amine-based curing agent. This mixture combines the high adhesion of epoxy resin and the high-temperature resistance of silicone resin, allowing for long-term use in high-temperature and high-humidity environments up to 125°C, meeting the application scenarios of electronic products. Simultaneously, it effectively isolates the copper electrode layer 2 from air contact.

[0042] In this embodiment, the protective layer 3 has a thickness of 10 μm, which can further reduce the impact of the protective layer 3 thickness on the antenna frequency characteristics. The protective layer 3 thickness can be greater than the copper layer thickness, resulting in better protection.

[0043] like Figure 3 A pin 21 is soldered onto the copper electrode layer 2. One end of the pin 21 is fixed to the copper electrode layer 2, and the other end extends through the protective layer 3. The extension length is 2-3mm, which facilitates subsequent connection with external circuits. This design allows the pin 21 to be directly soldered to the copper electrode layer 2 to achieve stable electrical conduction with low contact resistance. The other end extends through the protective layer 3 made of resin composition, which not only breaks through the insulation barrier to build an external conductive channel, but also ensures that the protective layer 3 completely covers the top and sides of the copper electrode layer 2, achieving long-term anti-oxidation. At the same time, the protective layer 3 forms a wrapping limit at the point where the pin 21 passes through, improving the mechanical firmness of the pin 21 connection. It also eliminates the need for additional large-area processing of the protective layer 3, adapting to the integration and assembly requirements of electronic components (such as antennas) and fitting the actual application layout of electronic products.

[0044] The present invention also includes a method for preparing the above-mentioned copper electrode, a method for manufacturing a copper electrode, wherein the copper electrode is printed on a substrate 1, comprising the following steps: S1. Copper paste is printed on substrate 1 using screen printing technology. The mesh size of the screen is 200-400 mesh, preferably 250 mesh. If the mesh size is lower than 200 mesh, the copper paste leakage will be too large, which will easily lead to an excessively thick copper paste wet film, irregular electrode pattern edges, and the thickness of the copper electrode layer 2 after subsequent sintering will exceed the design range of 5-15μm. It may also cause insufficient density of the conductive layer. If the mesh size is higher than 400 mesh, the copper paste leakage resistance will increase, the printing efficiency will be greatly reduced, and uneven copper paste coating and incomplete leakage will easily occur, resulting in incomplete electrode patterns. In this embodiment, a 250 mesh screen is preferred, which is the optimal value in this range. It can balance printing efficiency, pattern accuracy and copper paste coating thickness, and perfectly meet the preparation requirements of copper electrode layer 2.

[0045] The copper paste composition, by percentage by mass, includes the following components: 50-80% copper powder, 3-10% inorganic ceramic additives, 10-20% organic solvents, and 0.1-5% polymer resin.

[0046] Copper powder is the core conductive phase of copper paste and the main film-forming material of copper electrode layer 2. In this embodiment, copper powder with a particle size of less than 1 μm is preferred. This type of copper powder has a large specific surface area, and the particles are more tightly bonded during sintering, forming a dense electrode microstructure and ensuring the high conductivity of copper electrode layer 2. The lower limit of the proportion is 50%: if it is lower than this value, the proportion of conductive copper powder is insufficient, the spacing between conductive particles in the electrode layer is too large, the contact resistance increases sharply, and the conductivity decreases significantly. The upper limit of the proportion is 80%: if it is higher than this value, the proportion of other additives (additives, organic solvents, resins) is compressed, which will lead to poor printability and formability of copper paste, easy powdering during the drying stage, and easy cracking and warping during the sintering stage.

[0047] Inorganic ceramic additives are auxiliary functional phases in copper paste. Their core function is to enhance the adhesion between the copper paste and the substrate 1 (such as ceramic substrate 1), while simultaneously regulating the sintering shrinkage rate of the copper paste. This prevents cracking and warping of the copper electrode layer 2 due to excessive shrinkage differences between it and the substrate 1 during sintering. They also help improve the mechanical strength of the copper electrode layer 2. If the proportion is less than 3%, the adhesion and shrinkage regulation effects are insufficient, and the copper electrode layer 2 is prone to detaching from the substrate 1 or cracking after sintering. If the proportion is greater than 10%, the insulating ceramic material will dilute the conductive copper powder, leading to a decrease in the conductivity of the electrode layer.

[0048] Organic solvents serve as the dispersion medium and carrier for copper paste, dissolving and dispersing solid particles such as copper powder and inorganic ceramic materials. This allows the copper paste to form a uniform paste system with good leveling and stencil properties, ensuring that the copper paste can be uniformly and continuously stenciled onto substrate 1 during screen printing. A ratio below 10% results in an overly viscous copper paste, making stencil printing difficult and prone to scratches and discontinuous patterns. A ratio above 20% results in an overly thin copper paste, leading to drips after printing, resulting in blurred electrode patterns, uneven thickness, and increased drying time.

[0049] The polymer resin acts as a temporary binder for the copper paste, functioning only during the printing and drying stages. It binds solid particles such as copper powder and inorganic ceramic materials together, ensuring that the copper paste forms a dry film with sufficient strength after being coated on the substrate 1, preventing powder shedding, deformation, and pattern damage before drying. This resin completely decomposes and volatilizes during the subsequent high-temperature sintering stage at 600~850℃, leaving no residue in the final copper electrode layer 2. If the ratio is less than 0.1%, the bonding effect is insufficient, and the dry film is easily damaged; if it is higher than 5%, impurities such as carbides are easily left after sintering, which can damage the density of the copper electrode layer 2 and increase contact resistance.

[0050] In this embodiment, the preferred composition of the copper paste is 65% copper powder, 6% inorganic ceramic additive, 15% organic solvent, and 3% polymer resin. This ratio falls within a reasonable range for each component and represents a balanced value optimized through process optimization. It is suitable for the preparation requirements of a 5-15μm copper electrode layer 2, balancing the screen printing suitability of the copper paste with the conductivity and structural properties of the electrode layer after sintering. The 65% copper powder serves as the core conductive phase, ensuring a sufficient proportion of conductive particles while avoiding excessive proportions that could degrade the paste's formability. The 6% inorganic ceramic additive effectively improves the adhesion between the copper paste and the substrate 1, regulates sintering shrinkage, and does not dilute the conductive phase, thus maintaining conductivity. The 15% organic solvent provides a suitable copper paste consistency, ensuring smoothness and printability during screen printing. The 3% polymer resin provides sufficient temporary adhesion, preventing powder shedding after printing, and completely decomposes and volatilizes during high-temperature sintering, leaving no residual impurities that could affect the density of the electrode layer.

[0051] S2. Drying the copper paste at a temperature of 80~150℃ for 5~10 minutes is a crucial pretreatment step in the preparation of copper electrode layer 2, which connects screen printing and pre-high-temperature sintering. The core process involves controlling the temperature and time to dry the printed copper paste wet film, removing organic solvents and allowing the polymer resin to gently solidify and form temporary adhesion. This ensures that copper powder, inorganic ceramic materials, and other solid particles are tightly bonded into a structurally stable dry film, preventing powder shedding and pattern deformation during subsequent transfer and sintering. It also prevents rapid evaporation of organic solvents during direct high-temperature sintering, which could cause blistering and cracking of the film layer, thus laying a solid structural foundation for the densification sintering in S3.

[0052] The drying temperature of 80~150℃ is an optimized range that balances efficient evaporation of organic solvents with compatibility with polymer resins: if the temperature is below 80℃, the organic solvents will evaporate too slowly, and the residual solvents will boil and expand during subsequent high-temperature sintering, causing blistering and pinholes in the electrode layer; if the temperature is above 150℃, the rapid boiling of organic solvents will easily cause the film layer to peel and generate internal pores, and may also cause the polymer resin to be over-cured in advance, making it difficult to completely decompose and volatilize during sintering, and the residual carbide impurities will increase the electrode contact resistance.

[0053] A drying time of 5-10 minutes is a reasonable range to ensure uniform drying of the copper paste wet film, allowing the organic solvents in all parts of the film to evaporate fully and simultaneously, resulting in a consistent degree of curing of the dry film. If the drying time is less than 5 minutes, organic solvents will remain inside the film, making sintering prone to blistering and cracking; if the drying time exceeds 10 minutes, it will not only prolong the production cycle and reduce the preparation efficiency, but will also cause the dry film to become over-dried and brittle, making it prone to powder shedding and edge chipping during transportation, thus damaging the integrity of the electrode pattern.

[0054] S3. Sinter the copper electrode layer 2 in an inert gas atmosphere at a temperature of 600-850℃ for 5-10 minutes. This step is the core densification process for forming the copper electrode layer 2. It follows the dry film treatment after the copper paste is dried, transforming the dry film into a dense copper electrode layer 2 with high conductivity and strong adhesion to the substrate 1 through high-temperature sintering. The core function of the inert gas atmosphere is to isolate oxygen in the air, preventing copper powder from being oxidized to copper oxide at high temperatures, thus avoiding a significant decrease in the conductivity of the electrode layer. The inert gas used is generally nitrogen, argon, or other gases that do not react with copper, creating an oxygen-free sintering environment and solving the core problem of copper's active chemical properties and easy oxidation.

[0055] The sintering temperature is 600~850℃. This range is suitable for the sintering characteristics of copper powder with a particle size of <1μm. When the temperature is below 600℃, the bonding force between copper powder particles is insufficient, and a dense metal sintered body cannot be formed. The electrode layer has high porosity and poor conductivity and mechanical strength. When the temperature is above 850℃, the copper powder is prone to excessive grain growth and overburning. It will also aggravate the difference in thermal expansion between the copper electrode layer 2 and the substrate 1, causing cracking and warping, while increasing production energy consumption.

[0056] The purpose of heat preservation is to ensure that all parts of the copper electrode layer 2 are heated evenly, to ensure that the copper powder is fully sintered and dense, and to allow the polymer resin in the copper paste to completely decompose and volatilize without residue. It also allows the inorganic ceramic additives to achieve a good interface bond with the substrate 1, thereby improving the adhesion of the electrode layer. If the heat preservation is too short, the sintering will be insufficient and the resin will not decompose completely, resulting in poor electrode layer performance. If the heat preservation is too long, it will easily lead to excessive growth of copper grains, which will reduce conductivity, and will also prolong the production cycle and reduce efficiency.

[0057] S4. A protective paste is printed onto the copper electrode layer 2 using screen printing technology. S4 is the core forming process for the preparation of the copper electrode protective layer 3. It follows the high-temperature sintering of the dense copper electrode layer 2 in S3, laying the foundation for the subsequent curing of the antioxidant protective layer 3 in S5. It is one of the key steps to achieve long-term anti-oxidation of the copper electrode. This step uses screen printing technology to coat the surface of the copper electrode layer 2 with the protective paste. This not only unifies with the copper paste printing process in S1, improving overall production efficiency and reducing process adaptation costs, but also allows for precise control of the coating thickness and pattern accuracy of the protective paste through the mesh size design, adapting to the 35-25μm thickness requirement of the protective layer. This ensures that the paste is uniformly and continuously coated on at least the top and side preset areas of the copper electrode layer 2, achieving effective coverage of the copper electrode layer 2 after subsequent curing.

[0058] The protective slurry composition, by percentage by mass, includes the following components: 20-50% epoxy resin, 10-20% silicone resin, 10-30% saturated resin, and 2-10% curing agent.

[0059] Epoxy resin serves as the core film-forming phase, comprising 20-50% of the composition, making it the main framework of protective layer 3. Its excellent adhesion, mechanical strength, and chemical stability ensure that protective layer 3 tightly coats the copper electrode layer 2, preventing contact between oxygen and moisture. A content below 20% results in a loose film and protective failure; a content above 50% leads to brittle and hard protective layer 3, making it susceptible to cracking under thermal cycling.

[0060] Silicone resin constitutes 10-20% of the functional modification phase. Its core function is to enhance the high-temperature resistance and hydrophobicity of the protective layer 3, compensating for the insufficient temperature resistance of epoxy resin and adapting it to the potential high-temperature operating environment of the electrode. Insufficient proportion results in a weak modification effect, while excessive proportion will reduce the interfacial adhesion between the protective layer 3 and the copper electrode.

[0061] Saturated resin, comprising 10-30% of the process and toughness modifier, is primarily used to optimize the rheological properties of the paste, making it suitable for the stencil printing and leveling requirements of screen printing. It also enhances the flexibility of the cured protective layer 3, preventing it from peeling off due to thermal expansion differences. Too low a proportion will worsen the printability of the paste, while too high a proportion will dilute the main resin, reducing the overall protective strength.

[0062] The curing agent is an amine-based curing agent, such as dicyandiamide. The curing agent is a crosslinking trigger phase of 2-10%, which is crucial for the formation of a three-dimensional network structure in the resin system. A proportion below 2% will lead to incomplete resin curing, resulting in a significant decrease in the strength and protective properties of the protective layer 3; a proportion above 10% will cause the curing reaction to be too fast, generating internal stress and causing cracks in the protective layer 3. Unreacted curing agent may also remain, affecting the durability of the protection.

[0063] The protective slurry also includes an organic solvent; the organic solvent is selected from at least one of ethanol, ethyl acetate, and propylene glycol methyl ether, and the amount used is 10-20% by weight. The organic solvent completely evaporates during the heating curing or UV curing process and leaves no residue in the final protective layer 3.

[0064] The organic solvent serves as a dispersion medium and consistency regulator for the protective paste. The epoxy resin, silicone resin, and curing agent in the protective paste are mostly viscous or solid, with poor flowability and dispersibility, making them unsuitable for direct screen printing. Adding the organic solvent allows for uniform dissolution and dispersion of the components, adjusting the overall rheological properties and consistency of the paste. This ensures the protective paste possesses good stencil and leveling properties, guaranteeing uniform and continuous coating on the copper electrode layer 2 surface during the S4 process, preventing printing scratches, pattern discontinuities, and uneven coating.

[0065] At least one of ethanol, ethyl acetate, and propylene glycol methyl ether was chosen because these solvents have good compatibility with the resin, curing agent, and other components of the protective paste, will not react chemically, and will not corrode the sintered copper electrode layer 2. At the same time, these solvents are low to medium boiling point organic solvents with controllable evaporation rates, perfectly suited to the subsequent 100~150℃ heating curing or UV curing process conditions. They will not be too difficult to volatilize due to excessively high boiling points, nor will they cause the paste to dry too quickly during printing, resulting in problems such as screen clogging and poor leveling.

[0066] Ensuring complete evaporation and no residue of the organic solvent during curing is a core design principle for the long-lasting antioxidant effect of the protective layer 3. The protective function of the protective layer 3 relies on its dense resin cross-linked structure. If solvent residue remains, it will form bubbles and pores within the protective layer 3, compromising its oxygen and water barrier properties and significantly reducing its protective effect. Simultaneously, residual solvent may also affect the complete cross-linking and curing of the resin, leading to a decrease in the mechanical strength of the protective layer 3, its adhesion to the copper electrode layer 2, and even introducing impurities that affect the conductivity of the copper electrode layer 2. This design ensures that the cured protective layer 3 is a dense structure formed by pure resin cross-linking, fundamentally avoiding the above problems and guaranteeing the protective performance of the protective layer 3 and the overall performance of the copper electrode.

[0067] S5. Curing the protective slurry to form a protective layer 3 on the surface of the copper electrode layer 2, thus obtaining the copper electrode. The protective slurry is cured by heat curing or UV curing. The heat curing conditions are 100~150℃ for 10~30min, and the UV curing conditions are irradiation with a 100W UV lamp for 2~5 seconds.

[0068] The epoxy resin, silicone resin, saturated resin, and amine curing agent in the protective slurry need to undergo a cross-linking reaction triggered by the curing process to form a stable three-dimensional network resin structure, transforming the originally paste-like protective slurry into a dense and tough solid protective layer 3. At the same time, the organic solvents in the slurry will completely evaporate without residue during the curing process, ensuring the oxygen-proof and water-proof protective performance of the protective layer 3. Furthermore, the cured protective layer 3 can achieve good interfacial bonding with the copper electrode layer 2, meeting the design requirements of a thickness of 5-25μm and maintaining a thickness ratio of 1:0.8~1.5 with the copper electrode layer 2, thus balancing the protective effect and the overall performance of the electrode.

[0069] Setting the process parameters to 100~150℃ and 10~30min is an optimized range suitable for amine curing agents and resin systems. Moreover, this temperature is much lower than the 600~850℃ required for sintering the copper electrode layer 2, so it will not cause the copper electrode layer 2 to grow grains, oxidize, or peel off from the substrate 1.

[0070] The curing parameters of 2-5 seconds of 100W UV lamp irradiation are a rapid curing solution designed specifically for photoinitiating amine curing agents. This method is a cold curing process with no obvious thermal effect, which can effectively avoid thermal damage to the sintered copper electrode layer 2, while significantly improving the curing production efficiency of the protective layer 3. These curing parameters are suitable for protective slurry systems without added organic solvents.

[0071] This invention also discloses an electronic component, comprising a substrate 1 and the aforementioned copper electrode, wherein the copper electrode is printed on the substrate 1; or comprising a substrate 1 and a copper electrode manufactured using the aforementioned copper electrode manufacturing method, wherein at least one of the aforementioned copper electrodes is disposed on the substrate 1. The electronic component is an antenna, capacitor, LTCC, chip resistor, sensor, or filter, and the substrate 1 is ceramic. Of course, the substrate 1 can also be replaced with other materials according to actual production needs.

[0072] This invention uses a radio frequency (RF) antenna as the core adapter component for the copper electrode. RF antennas have stringent requirements regarding conductivity, high-frequency transmission characteristics, resistance to complex environments, and manufacturing costs. The copper electrode described in this invention possesses conductivity comparable to silver electrodes and superior high-frequency characteristics, eliminating the electron migration issues present in traditional silver electrodes. Furthermore, the protective layer covering the top and sides of the copper electrode effectively solves the technical challenge of easy oxidation of the copper electrode, achieving long-term oxidation resistance. Combined with the structural stability of the ceramic substrate 1, the RF antenna can operate stably in a wide temperature range of -40℃ to 125℃ and in complex environments such as humidity, salt spray, and ultraviolet radiation. The ceramic substrate 1 is a conventional adapter substrate 1 used in the industrial production of RF antennas. The copper electrode of this invention is formed on the surface of the ceramic substrate 1 using a screen printing process, making it fully compatible with the existing silver electrode manufacturing process for RF antennas. No modifications to existing production lines are required, allowing direct replacement of silver electrodes with copper electrodes in RF antennas. While ensuring that the performance indicators of the RF antenna are not reduced or even improved, the manufacturing cost of the electrode material is significantly reduced, enhancing the market competitiveness of the RF antenna.

[0073] For RF components such as capacitors, LTCCs, chip resistors, sensors, and filters, the conventional substrate 1 used in industrial production is also ceramic, consistent with the substrate 1 selection of the electronic components of this invention. Furthermore, the electrode fabrication of these components all employs a screen printing process, which is highly compatible with the copper electrode fabrication process of this invention. Therefore, the copper electrodes and corresponding fabrication methods described in this invention can be directly adapted to these components. When fabricating these components, the number, arrangement, and thickness of the copper electrodes can be flexibly designed on the ceramic substrate according to the electrode coupling requirements of capacitors, the integrated conductivity requirements of LTCCs, the resistance design requirements of chip resistors, the signal sensing requirements of sensors, and the signal filtering requirements of filters. The screen printing process of this invention is used to fabricate the copper electrodes. Leveraging the high performance, low cost, and long-term oxidation resistance advantages of the copper electrodes of this invention, they replace the traditional precious metal electrodes such as silver used in these components, achieving cost reduction and efficiency improvement for these RF components, while simultaneously enhancing their structural stability and operational durability.

[0074] Example 2 The main difference between this embodiment and Embodiment 1 is that: Figure 2 A clearance hole 31 is made at the location where the copper electrode layer 2 needs to be electrically connected, corresponding to the protective layer 3. The diameter of the hole is set to 0.5-1mm according to the connection requirements. The clearance hole 31 is designed to reserve space for the connection between the pin 21 and the copper electrode layer 2.

[0075] In order to provide clearance holes 31 in the protective layer 3, in step S4, when printing the protective paste, the screen is set to a meshless structure corresponding to the clearance holes 31. Specifically, the protective layer 3 prepared in this embodiment does not completely cover the entire surface of the copper electrode layer 2, but has clearance holes 31 at preset positions. These clearance holes 31 can be used for subsequent electrode welding, conductive connection, or sensor probe exposure, etc., according to actual application requirements.

[0076] To accurately form the aforementioned clearance hole 31 structure, this solution employs a targeted structural design for the screen used in screen printing: the portion of the screen corresponding to the clearance hole 31 in the protective layer 3 is treated to have a mesh-free structure. Specifically, this can be achieved using a screen sealing process, such as applying a sealing adhesive or attaching a light-blocking film to seal the original mesh in that area. During the printing process in step S4, when the squeegee moves the protective paste across the screen, the paste can only be printed from the mesh areas of the screen to the surface of the copper electrode layer 2; the mesh-free areas of the screen will block the paste penetration, leaving the corresponding copper electrode layer 2 surface uncovered by the protective paste.

[0077] After printing, the area covered by the protective paste undergoes a curing process, forming a continuous protective layer. The area not covered by the paste naturally forms clearance holes 31 that perfectly correspond in size and position to the meshless areas of the screen. The clearance holes 31 formed using this process offer advantages such as precise positioning, neat edges, and integrated molding with the protective layer 3. This eliminates the need for additional drilling, etching, or other post-processing steps, effectively simplifying the production process and improving the efficiency and yield of copper electrode fabrication.

[0078] Example 3 The main difference between this embodiment and Embodiment 1 is that the copper paste composition, by percentage mass ratio, includes the following components: 50% copper powder, 3% inorganic ceramic additives, 10% organic solvent, and 2% polymer resin.

[0079] The copper powder content of 50% is the lower limit for the conductive phase. Although it is the minimum, it still ensures effective contact of conductive particles and avoids a sharp increase in contact resistance due to excessive particle spacing, thus meeting the basic conductivity requirements of the copper electrode layer 2. The inorganic ceramic additive content of 3% is the lower limit for the auxiliary functional phase, which can improve the adhesion of the substrate 1 and adjust the sintering shrinkage rate, preventing the copper electrode layer 2 from falling off or cracking during sintering and use, and ensuring the stability of the electrode layer structure. The organic solvent content of 10% is the lower limit for the dispersion medium, which can achieve uniform dispersion of solid components such as copper powder and inorganic ceramic materials, giving the copper paste basic stencil printing and leveling properties, and making it suitable for printing processes using 200~400 mesh screens.

[0080] The use of 2% polymer resin, although not the lower limit of the proportion of this component, is still within the reasonable range of 0.1% to 5%, which can provide sufficient temporary adhesion for copper paste, effectively preventing powdering and pattern damage during the printing and drying stages. Moreover, this proportion can be completely decomposed and volatilized during subsequent high-temperature sintering at 600~850℃, leaving no carbides or other impurities, and will not damage the density of copper electrode layer 2.

[0081] The proportioning design of this embodiment further confirms the scientific nature and practicality of the copper paste proportioning range set by the present invention. It shows that the copper paste proportioning of the invention is not only feasible for the preferred value of Example 1, but the proportioning combination within the entire limited range can achieve the effective preparation of copper electrode layer 2. This not only broadens the process flexibility of adjusting the copper paste proportioning according to equipment conditions, cost control and actual performance requirements in production, but also clarifies the performance baseline of the copper paste proportioning of the present invention, providing more proportioning options for industrial mass production.

[0082] Example 4 The main difference between this embodiment and Embodiment 1 is that the copper paste composition, by percentage mass ratio, includes the following components: 80% copper powder, 5% inorganic ceramic additives, 20% organic solvent, and 4% polymer resin.

[0083] The upper limit for the proportion of conductive phase is 80% copper powder. At this maximum proportion, the contact density of conductive particles reaches the optimal level, which can further improve the conductivity of copper electrode layer 2. At the same time, this proportion does not excessively compress the proportion of other additives, leaving enough room for their proportion, avoiding problems such as poor slurry formation, powder loss during drying, and sintering cracking caused by excessive copper powder proportion. The upper limit for the dispersion medium is 20% organic solvent. This proportion can fully disperse the high proportion of copper powder, ensuring that the copper paste forms a uniform paste system with good stencil and leveling properties, which is suitable for 200~400 mesh screen printing requirements. Moreover, it does not cause the slurry to be too thin or the printing to run due to excessive proportion, and can ensure the integrity of the electrode pattern.

[0084] The inorganic ceramic additive (5%) and polymer resin (4%) both fall within their respective proportion ranges and form a suitable combination with the upper limits of copper powder and organic solvent. The 5% inorganic ceramic additive can effectively improve the adhesion between the copper paste and the substrate 1, regulate the sintering shrinkage rate, prevent the copper electrode layer 2 from falling off and cracking after sintering, and will not dilute the high proportion of conductive phase, thus not affecting the conductivity of the electrode. The 4% polymer resin can provide sufficient temporary adhesion for the copper paste with a high proportion of copper powder, preventing powder shedding and pattern damage during the printing and drying stages. Moreover, this proportion can be completely decomposed and volatilized during high-temperature sintering at 600~850℃, leaving no carbide residue and not damaging the density of the copper electrode layer 2.

[0085] This formulation design further corroborates the scientific validity and practicality of the copper paste formulation range of this invention, demonstrating that not only are combinations of preferred and lower limit values ​​within the range feasible, but combinations of upper limit values ​​for key components and appropriate values ​​for other additives within the range can also achieve effective preparation of the copper electrode layer 2. This formulation can meet the demand for higher conductivity of the copper electrode layer 2 in production, broadening the process flexibility for adjusting the copper paste formulation according to actual performance requirements and production conditions. It also clarifies the performance upper limit of the copper paste formulation of this invention, providing formulation options for differentiated electrode performance requirements in industrial mass production.

[0086] To visually verify the actual performance of copper electrodes prepared with different copper paste ratios in this invention when applied to antennas, and to compare the performance differences between the products of this invention and similar competing products on the market, this application conducted specific tests on the core performance indicators of the antenna products prepared in Embodiments 1, 3, and 4, as well as competing antennas on the market. The test indicators take into account the structural and mechanical core performance of the copper electrode layer 2 and the key operating performance of the radio frequency antenna. The specific test results are shown in Table 1.

[0087] Table 1. Comparison of antenna performance parameters for each embodiment

[0088] Among the above test indicators, porosity directly reflects the micro-density of the copper electrode layer 2. The lower the porosity, the denser the electrode layer structure, and the better the conductivity, oxidation resistance, and signal transmission stability. Pull-out force characterizes the bonding strength between the copper electrode layer 2 and the substrate 1. The higher the value, the stronger the bonding between the electrode layer and the substrate 1, and the less likely it is to fall off, warp, or cause structural failures during use. Antenna electrical performance parameter 1 and electrical performance parameter 2 are the core operating indicators of the radio frequency antenna. Their values ​​directly determine the antenna's signal transmission efficiency, frequency band adaptability, and other key performance characteristics.

[0089] The test results clearly show that the antenna products prepared in each embodiment of the present invention are significantly superior to competing products on the market in all aspects of performance: the porosity of the copper electrode layer 2 of competing products reaches 10.2%, which is much higher than that of the embodiments of the present invention, reflecting poor electrode layer density. In contrast, Embodiment 4 of the present invention uses a high proportion of 80% copper powder, resulting in a tighter bonding of conductive particles and a porosity as low as 5.3%, demonstrating the best density performance. The pull-out force of each embodiment of the present invention is 18N or higher, with Embodiment 1 reaching 21N, far exceeding the 13N of competing products. This demonstrates that after the optimization of the ratio and process treatment, the bonding strength between the copper electrode layer 2 and the substrate 1 is greatly improved, resulting in excellent structural stability. In terms of antenna electrical performance, the core electrical performance parameters of each embodiment of the present invention are superior to those of competing products, with better signal transmission performance, which can better meet the working requirements of radio frequency antennas.

[0090] Meanwhile, the products from Example 1 (preferred copper paste ratio), Example 3 (lower limit copper paste ratio), and Example 4 (upper limit copper paste ratio) all exhibited excellent and stable performance. This result further confirms that the copper paste ratio range defined by this invention is scientific and practical. Different ratio combinations within this range can produce high-performance copper electrodes and corresponding antenna products. This provides industrial mass production with the flexibility to adjust the ratio according to production conditions and cost requirements, while ensuring the baseline and stability of product performance. It solves the problems of limited ratio and large performance fluctuations in traditional copper electrode processes.

[0091] To further verify the rationality of the structural design and practical application performance of the copper electrode of this invention through visualization, this application combines... Figures 4-12 The copper electrode of this invention and the traditional silver electrode are compared and characterized from three core dimensions: radio frequency electrical performance, sintering microstructure, and electrode layer thickness structure. The detection conditions and scientific interpretations of each figure are as follows: Figure 4 The graph shows a comparison of the VSWR (Voltage Standing Wave Ratio) of the copper and silver electrodes, with a test frequency range of 1475~1650MHz. The horizontal axis represents the operating frequency, and the vertical axis represents the VSWR value. A lower VSWR value indicates better impedance matching and lower reflection loss in RF signal transmission. The graph shows that the VSWR value of the copper electrode in this invention is generally lower than that of the silver electrode across the entire test frequency range, indicating superior impedance matching and stability in RF signal transmission.

[0092] Figure 5 This graph compares the signal transmission efficiency of copper and silver electrodes, with the test frequency band ranging from 1555 to 1610 MHz. The vertical axis represents the transmission efficiency value. Overall, the copper electrode exhibits higher transmission efficiency than the silver electrode within this test frequency band, especially in the 1570–1580 MHz core RF operating frequency band, where the efficiency advantage is more significant and better suited to the actual operating requirements of electronic components.

[0093] Figure 6 This is a comparison of the gain of copper electrodes and silver electrodes, along with a comparison of the test frequency bands and efficiency. Figure 1 The vertical axis represents the gain value, with a higher value indicating stronger RF signal radiation capability. Copper electrodes exhibit better gain performance in the core operating frequency band, and the gain attenuation trend is more gradual at both ends of the test frequency band, demonstrating a wider effective operating frequency band.

[0094] Figure 7 , Figure 8 The images are 200x scanning electron microscope (SEM) magnifications of the sintered appearance of the copper electrode and the silver electrode, respectively. From the low-magnification microscopic perspective, it can be seen that the surface morphology of the copper electrode after sintering is smoother, without obvious particle agglomeration, protrusions or depressions, and the overall morphology is similar to that of the sintered surface of the silver electrode.

[0095] Figure 9 , Figure 10 The images show 1000x scanning electron microscope (SEM) magnifications of the sintered appearance of copper and silver electrodes, respectively. Under high magnification, it can be observed that the copper powder in the copper electrode has a tighter grain bond, a denser microstructure, and a more uniform and smaller pore distribution after sintering. The silver electrode has a small number of grain gaps and local pores. This is the main difference in the microstructure between the two electrodes and the core reason why the copper electrode has a lower porosity.

[0096] The above Figures 4-12 The visualization results corroborate the performance test data mentioned above, which not only intuitively demonstrate the optimized advantages of the copper electrode of the present invention in structural design, micro-forming, and radio frequency electrical performance, but also objectively reflect the performance characteristics of the traditional silver electrode. This provides sufficient image and data support for the copper electrode of the present invention to replace the silver electrode while ensuring performance.

[0097] The above description is merely a preferred embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the invention should be included within the scope of protection of the invention.

Claims

1. A copper electrode, characterized in that, It includes a copper electrode layer and a protective layer, wherein the protective layer covers at least the top and side surfaces of the copper electrode layer; the ratio of the thickness of the copper electrode layer to the thickness of the protective layer is 1:0.8~1.5, and the protective layer is made of a resin composition.

2. A copper electrode according to claim 1, characterized in that: The resin composition comprises, by weight percentage: 20-50% epoxy resin, 10-20% silicone resin, 10-30% saturated resin, and 2-10% curing agent, wherein the curing agent is an amine curing agent.

3. A copper electrode according to claim 1, characterized in that: The protective layer is provided with clearance holes.

4. A copper electrode according to claim 1, characterized in that: The copper electrode layer is welded with pins, one end of which is fixed to the copper electrode layer and the other end extends through the protective layer.

5. A copper electrode according to claim 1, characterized in that: The thickness of the copper electrode layer is 5-15 μm, and the thickness of the protective layer is 5-25 μm.

6. A copper electrode according to claim 5, characterized in that: The copper electrode layer has a thickness of 10 μm, and the protective layer has a thickness of 10 μm.

7. A method for manufacturing a copper electrode, used to manufacture the copper electrode according to any one of claims 1-6, wherein the copper electrode is printed on a substrate, characterized in that, Includes the following steps: S1. Copper paste is printed on the substrate using screen printing technology, with a screen mesh count of 200~400. S2. Dry the copper paste at a temperature of 80~150℃ for 5~10 minutes. S3. Sinter the copper electrode layer in an inert gas atmosphere at a sintering temperature of 600~850℃ and a holding time of 5~10min. S4. Use screen printing technology to print protective paste on the copper electrode layer; S5. Curing and protecting the slurry forms a protective layer on the surface of the copper electrode layer, thus obtaining the copper electrode.

8. A method for manufacturing a copper electrode according to claim 7, characterized in that: The copper paste composition, by percentage by mass, includes the following components: 50-80% copper powder, 3-10% inorganic ceramic additives, 10-20% organic solvent, and 0.1-5% polymer resin.

9. A method for manufacturing a copper electrode according to claim 8, characterized in that: The protective slurry composition, by percentage by mass, includes the following components: 20-50% epoxy resin, 10-20% silicone resin, 10-30% saturated resin, and 2-10% curing agent.

10. A method for manufacturing a copper electrode according to claim 9, characterized in that: The protective slurry also includes an organic solvent; the organic solvent is selected from at least one of ethanol, ethyl acetate, and propylene glycol methyl ether, and the amount used is 10-20% by weight percentage, and the organic solvent completely evaporates during the heating curing or UV curing process, leaving no residue in the final protective layer.

11. A method for manufacturing a copper electrode according to claim 9, characterized in that: The protective slurry is cured by heating or UV curing. The heating curing conditions are 100~150℃ for 10~30 minutes, and the UV curing conditions are irradiation with a 100W UV lamp for 2~5 seconds.

12. A method for manufacturing a copper electrode according to claim 7, characterized in that: The screen mesh count is 250 mesh, and the protective layer is provided with clearance holes. In step S4, when printing the protective paste, the screen mesh corresponding to the clearance hole is set to a meshless structure.

13. An electronic component, characterized in that, The invention comprises a substrate and a copper electrode as described in any one of claims 1-6, wherein the copper electrode is printed on the substrate; or comprises a substrate and a copper electrode manufactured using the method for manufacturing a copper electrode as described in any one of claims 7-12, wherein at least one of the copper electrodes is disposed on the substrate.

14. The electronic component according to claim 13, characterized in that: The electronic components are antennas, capacitors, LTCCs, chip resistors, sensors, or filters, and the substrate is ceramic.

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