Preparation process of composite electrode for ceramic chip

Abstract

The invention discloses a preparation process of a composite electrode for a ceramic chip, which comprises the following steps of: placing the ceramic chip in a clamping jig, thermally spraying an aluminum electrode layer on the surface of the ceramic chip through a first electrode spray gun, thermally spraying a copper electrode layer on the aluminum electrode layer through a second electrode spray gun, and performing nitrogen atomization spraying during spraying, and carrying out anti-oxidation treatment to obtain the ceramic chip of the composite electrode. The aluminum electrode layer and the copper electrode layer are sequentially sprayed on the surface of the ceramic chip, so that the binding force between the copper electrode layer and the ceramic chip can be improved; in the spraying process, nitrogen is adopted as compressed gas, so that the problem of oxidation of the ceramic chip can be avoided; the ceramic chip is subjected to anti-oxidation treatment, so that a stable anti-oxidation protection layer can be formed on the surface of the copper electrode layer, and the service life of a product is prolonged; the whole preparation process is reasonable in design, the structural stability, the conductivity and the durability of the ceramic chip electrode are effectively improved, and the overall performance of the product is improved.

Description

Technical Field

[0001] The invention relates to the field of ceramic chips, and in particular to a preparation process of a composite electrode for ceramic chips. Background Art

[0002] Ceramic chip is a basic component with ceramic material as the matrix, used to manufacture various electronic components. Ceramic chip has good electrical insulation, thermal stability and corrosion resistance, and is widely used in electronic components such as varistors, thermistors, ceramic capacitors, etc. The electrode on the ceramic chip refers to the conductive layer set on the ceramic substrate, which is used to realize the reception, transmission and distribution of electrical signals. The electrode is usually made of conductive metal material and is generally directly printed or plated on the surface of the ceramic chip to form a contact point connected to the external circuit or other devices.

[0003] In the prior art, in the traditional ceramic chip electrode preparation process, a single metal slurry is usually coated on the surface of the ceramic chip. However, the adhesion and conductivity of the single metal slurry are often difficult to meet the requirements at the same time, resulting in insufficient bonding between the electrode and the ceramic chip, affecting the overall performance; secondly, the stability of the single metal electrode during high-temperature treatment is poor, which can easily lead to material diffusion between the electrode and the ceramic chip due to interface reaction, affecting the long-term stability of the electrode; in addition, the ceramic chip electrode prepared in the traditional process has weak antioxidant properties and is prone to oxidation during use, thereby affecting the conductivity and service life of the product.

[0004] Therefore, the prior art has defects and needs to be improved. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a preparation process of a composite electrode for ceramic chips with high adhesion and anti-oxidation effect.

[0006] To achieve this purpose, the present invention adopts the following technical solution: A process for preparing a composite electrode for a ceramic chip, comprising the following steps:

[0007] S1. Place the cleaned ceramic chip in a fixture, and expose the sprayed surfaces at both ends of the ceramic chip to the fixture;

[0008] S2, hanging the clamping fixture with the ceramic chip on the chain conveyor, configuring a first station and a second station along the conveying direction of the chain conveyor, two first electrode spray guns are configured on the front and rear sides of the first station, and two second electrode spray guns are configured on the front and rear sides of the second station;

[0009] S3, the chain conveyor device drives the clamping fixture to move, and when the ceramic chip moves to the first station, the first electrode spray gun is used to thermally spray the aluminum electrode material onto the two spraying surfaces of the ceramic chip to form an aluminum electrode layer on the spraying surface of the ceramic chip;

[0010] S4. After the spraying of the aluminum electrode layer is completed, the chain conveyor device drives the clamping fixture to continue to move. When the ceramic chip moves to the second station, the copper electrode material is thermally sprayed on the surface of the aluminum electrode layer using the second electrode spray gun to form a copper electrode layer.

[0011] The second electrode spray gun uses nitrogen as compressed gas to atomize and spray the melted spray droplets onto the surface of the aluminum electrode layer of the ceramic chip during spraying.

[0012] S5. Take the clamping fixture out from the chain conveyor to obtain a ceramic chip with a composite electrode.

[0013] According to the technical solution, in the preparation process of the composite electrode for ceramic chips, in step S5, after the clamping fixture is taken out from the chain conveyor, it is also immersed in an antioxidant solution for antioxidant treatment to form an antioxidant protective layer on the surface of the copper electrode layer on both sides of the ceramic chip;

[0014] The immersion time of the ceramic chip in the antioxidant solution is 2-10 minutes. The preparation method of the antioxidant solution is: dissolving 2-methylbenzamidazole in a formic acid solution, adjusting the pH value to 3-5 to completely dissolve the 2-methylbenzamidazole, and obtaining the antioxidant solution.

[0015] By adopting the above technical scheme, in the preparation process of the composite electrode for ceramic chip, in the antioxidant solution, the concentration of 2-methylbenzalimidazole is 0.3-0.4 mol / L, and the concentration of formic acid is 0.1-0.2 mol / L.

[0016] By adopting the above technical scheme, in the preparation process of the composite electrode for ceramic chips, after the immersion is completed, the anti-oxidation protective layer is subjected to infrared irradiation and drying treatment, wherein the radiation power of the infrared irradiation is 400-750mw and the infrared irradiation time is 1-2h.

[0017] According to the above technical solution, in the preparation process of the composite electrode for ceramic chip, the aluminum electrode material and the copper electrode material are alloy wire structures;

[0018] The first electrode spray gun and the second electrode spray gun melt the aluminum electrode material or the copper electrode material of the alloy wire structure and spray it on the ceramic chip by arc spraying;

[0019] Among them, the spraying parameters of the first electrode spray gun and the second electrode spray gun are: spraying voltage is 32-40V, spraying current is 100-200A, spraying gas pressure is 0.5-0.8Mpa, gas flow rate is 10-30L / min, wire feeding voltage is 10-15V, wire feeding rate is 0.8-1.2m / min, and spraying distance is 150-260mm.

[0020] By adopting the above technical solution, in the preparation process of the composite electrode for ceramic chips, the thickness of the aluminum electrode layer is 10-80 μm, and the thickness of the copper electrode layer is 5-25 μm.

[0021] According to the above technical solution, in the preparation process of the composite electrode for ceramic chip, the clamping fixture includes a carrier plate, a first clamping plate and a second clamping plate;

[0022] The carrier plate is provided with positioning holes arranged in an array, the shape of the positioning holes is adapted to the shape of the ceramic chip, and the positioning holes are used to position and place the ceramic chip to be sprayed;

[0023] The first clamping plate and the second clamping plate are respectively arranged on the front and rear sides of the material carrying plate, and the first clamping plate and the second clamping plate are locked and connected by bolts;

[0024] The first clamping plate and the second clamping plate are provided with spray avoidance holes corresponding to the positions of the positioning holes, the area of ​​the spray avoidance holes is less than or equal to the area of ​​the positioning holes, and the spray avoidance holes are used for allowing spray droplets to be sprayed onto the spraying surface of the ceramic chip.

[0025] By adopting the above technical solution, in the preparation process of the composite electrode for ceramic chips, in step S3 and step S4, the spray gun nozzles of the first electrode spray gun and the second electrode spray gun are arranged directly opposite to the front and back sides of the clamping fixture; and the first electrode spray gun and the second electrode spray gun are respectively connected to the biaxial moving mechanism to adjust the positions of the first electrode spray gun and the second electrode spray gun;

[0026] The biaxial moving mechanism includes a lifting and moving module and a horizontal moving module. The lifting and moving module is used to adjust the height of the first electrode spray gun and the second electrode spray gun so that the sprayed molten droplets are covered and deposited on the spraying surfaces of all ceramic chips. The horizontal moving module is used to adjust the horizontal distance between the first electrode spray gun and the second electrode spray gun relative to the ceramic chip to control the deposition rate of the sprayed molten droplets.

[0027] Among them, during the spraying process, the movement rate of the lifting and moving module is 10-30mm / s.

[0028] By adopting the above technical solution, in the preparation process of the composite electrode for ceramic chip, the clamping fixture is connected to the chain conveying device through a hook;

[0029] The conveying speed of the chain conveyor is 2-4 m / min.

[0030] By adopting the above technical solution, in the preparation process of the composite electrode for ceramic chip, the ceramic chip is any one of the ceramic chips used for varistors, thermistors or ceramic capacitors.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention fixes the ceramic chip by a clamping fixture to prevent it from shifting during the spraying process, thereby improving the spraying accuracy; the first electrode spray gun can thermally spray the aluminum electrode material onto the spraying surface of the ceramic chip at the first station to form an aluminum electrode layer, and the second electrode spray gun can thermally spray the copper electrode material onto the aluminum electrode layer at the second station to form a copper electrode layer. Since the aluminum electrode layer has excellent adhesion, as a bottom material, it can improve the bonding force between the copper electrode layer and the ceramic chip, and the copper electrode layer has excellent electrical conductivity, which can effectively improve the performance of the ceramic chip; by accurately controlling the first electrode spray gun and The spraying parameters of the second electrode spray gun can make the sprayed molten droplets evenly distributed on the ceramic chip, effectively avoiding the problem of uneven thickness; in the spraying process, nitrogen is used as compressed gas to avoid oxidation problems of the ceramic chip; by performing anti-oxidation treatment on the ceramic chip, a stable anti-oxidation protective layer can be formed on the surface of the copper electrode layer, extending the service life of the product; infrared irradiation and drying treatment of the anti-oxidation protective layer can further improve the reliability of the anti-oxidation protective layer; the entire preparation process is reasonably designed, which effectively improves the structural stability, conductivity and durability of the ceramic chip electrode, and improves the overall performance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0035] Figure 1It is a schematic diagram of the thermal spraying operation of the present invention;

[0036] Figure 2 It is a schematic diagram of the explosion structure of the clamping fixture of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0039] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0040] Example 1

[0041] like Figure 1 and Figure 2 As shown, the embodiment of the present invention provides a process for preparing a composite electrode for a ceramic chip, comprising the following steps:

[0042] S1. Place the cleaned ceramic chip in a clamping fixture 10, and expose the sprayed surfaces at both ends of the ceramic chip to the clamping fixture 10, wherein the clamping fixture 10 includes a carrier plate 11, a first clamping plate 12 and a second clamping plate 13. The carrier plate 11 is provided with an array of positioning holes 110, the shape of the positioning holes 110 is adapted to the shape of the ceramic chip, and the positioning holes 110 are used to position and place the ceramic chip to be sprayed. The first clamping plate 12 and the second clamping plate 13 are respectively arranged at the front and rear sides of the carrier plate 11, and the first clamping plate 12 and the second clamping plate 13 are locked and connected by bolts 14. The first clamping plate 12 and the second clamping plate 13 are provided with positioning holes 110 corresponding to the positions of the positioning holes 110. A spray avoidance hole 120, the area of ​​which is less than or equal to the area of ​​the positioning hole 110, and the spray avoidance hole 120 is used for allowing spray droplets to be sprayed onto the spray surface of the ceramic chip; the positioning hole 110 in the clamping fixture 10 is adapted to the shape of the ceramic chip, so that the ceramic chip is firmly fixed in the clamping fixture 10 to prevent it from shifting during the spraying process, and the first clamping plate 12 and the second clamping plate 13 are provided with spray avoidance holes 120 corresponding to the positions of the positioning holes 110, and the area of ​​the spray avoidance holes 120 is less than or equal to the area of ​​the positioning holes 110. With such a configuration, the spray droplets can be sprayed only onto the predetermined spray surface of the ceramic chip to avoid affecting the non-spraying area, thereby improving the spraying accuracy.

[0043] S2. Hang the fixture 10 with the ceramic chip clamped on the chain conveyor 20 through a hook. A first station 201 and a second station 202 are arranged along the conveying direction of the chain conveyor 20. Two first electrode spray guns 31 are arranged on the front and rear sides of the first station 201. Two second electrode spray guns 32 are arranged on the front and rear sides of the second station 202. The conveying speed of the chain conveyor 20 is 2m / min to achieve a continuous and uniform spraying process. Two stations are arranged along the line direction of the chain conveyor 20, and different electrode spray guns are arranged at different stations to achieve step-by-step spraying, which effectively reduces repeated operation steps and changing time, and improves the electrode spraying efficiency of ceramic chips. It should be noted that in Figure 1 In the figure, the first electrode spray gun 31 and the second electrode spray gun 32 are only provided on the front side of the clamping fixture 10, while the first electrode spray gun 31 and the second electrode spray gun 32 on the back side of the clamping fixture 10 are not shown in the figure.

[0044] S3, the chain conveyor 20 drives the clamping fixture 10 to move. When the ceramic chip moves to the first station 201, the first electrode spray gun 31 is used to thermally spray the aluminum electrode material onto the two spraying surfaces of the ceramic chip to form an aluminum electrode layer on the spraying surface of the ceramic chip. The thickness of the aluminum electrode layer is 80μm. Aluminum has good adhesion. By preferentially spraying the aluminum electrode layer at the first station 201, a strong bonding force can be ensured between the electrode material and the ceramic chip, thereby increasing the adhesion performance of the electrode.

[0045] S4. After the spraying of the aluminum electrode layer is completed, the chain conveyor 20 drives the clamping fixture 10 to continue to move. When the ceramic chip moves to the second station 202, the second electrode spray gun 32 is used to cover the copper electrode material on the surface of the aluminum electrode layer by thermal spraying to form a copper electrode layer. The thickness of the copper electrode layer is 25 μm. The aluminum electrode layer serves as the bottom electrode and can provide a good adhesion base. By spraying the copper electrode layer on the surface of the aluminum electrode layer, the good bonding force between aluminum and the ceramic chip can be fully utilized to ensure that the copper electrode layer can be firmly attached to the aluminum electrode layer, thereby improving the stability of the overall structure and the mechanical strength of the electrode. In addition, the copper electrode layer has excellent electrical conductivity, which can meet the high conductivity requirements of the ceramic chip and improve product performance. In addition, the aluminum electrode layer can play an isolating role to prevent the copper electrode layer from directly contacting the ceramic chip, effectively avoiding interface reactions or material diffusion in high temperature environments, thereby improving the stability and durability between the electrode and the ceramic chip and extending the service life of the product.

[0046] The spray gun nozzles of the first electrode spray gun 31 and the second electrode spray gun 32 are arranged opposite to the front and back of the clamping fixture 10; and the first electrode spray gun 31 and the second electrode spray gun 32 are respectively connected to a double-axis moving mechanism 40 to adjust the positions of the first electrode spray gun 31 and the second electrode spray gun 32. The double-axis moving mechanism 40 includes a lifting and moving module 41 and a horizontal moving module 42. The lifting and moving module 41 is used to adjust the height of the first electrode spray gun 31 and the second electrode spray gun 32 so that the spray droplets cover and deposit on the spraying surface of all ceramic chips, and the horizontal moving module 42 is used to Adjust the horizontal distance between the first electrode spray gun 31 and the second electrode spray gun 32 relative to the ceramic chip to control the deposition rate of the sprayed molten droplets; during the spraying process, the movement rate of the lifting and moving module 41 is 10 mm / s; the setting of the lifting and moving module 41 and the horizontal moving module 42 can enable the first electrode spray gun 31 and the second electrode spray gun 32 to evenly spray the surface of the ceramic chip to avoid the problem of uneven spraying thickness; setting the lifting and moving module 41 to a movement rate of 10 mm / s can prevent the molten droplets from being too concentrated or dispersed during the spraying process, thereby ensuring the uniformity of the electrode.

[0047] In addition, when spraying, the second electrode spray gun 32 uses nitrogen as compressed gas to atomize and spray the molten spray droplets onto the surface of the aluminum electrode layer of the ceramic chip; nitrogen is an inert gas and does not react with metal materials. Using nitrogen as the spray gas to spray the spray droplets onto the ceramic chip can prevent the molten metal particles from being oxidized during the spraying process, thereby ensuring the purity and good conductivity of the electrode layer.

[0048] The aluminum electrode material and the copper electrode material are of alloy wire structure. The first electrode spray gun 31 and the second electrode spray gun 32 melt the aluminum electrode material or the copper electrode material of the alloy wire structure by arc spraying and spray them on the ceramic chip. The spraying parameters of the first electrode spray gun 31 and the second electrode spray gun 32 are as follows: the spraying voltage is 32V, the spraying current is 150A, the spraying gas pressure is 0.8Mpa, the gas flow rate is 30L / min, the wire feeding voltage is 15V, the wire feeding rate is 1.2m / min, and the spraying distance is 260mm. The spraying current determines the strength and melting speed of the arc. Setting the spraying current to 150A can ensure sufficient energy input. The alloy wire is quickly melted to form spray droplets, while the thickness and density of the electrode are controlled; in this embodiment, the spraying gas pressure can atomize the molten metal material and spray it onto the ceramic chip. The moderate gas pressure can ensure that the spray droplets can be evenly diffused and deposited on the surface of the ceramic chip without being too sparse or too dense; the spraying distance affects the kinetic energy and coverage of the spray droplets reaching the ceramic chip. If the spraying distance is too close, the kinetic energy of the spray droplets is too large when they reach the surface of the ceramic chip, which can easily cause uneven electrode accumulation; if the spraying distance is too far, the spray droplets have cooled before reaching the ceramic chip, and the adhesion is reduced, resulting in insufficient bonding between the electrode layer and the ceramic chip.

[0049] S5. After the clamping fixture 10 is taken out from the chain conveyor 20, it is also immersed in an antioxidant solution for antioxidant treatment. The ceramic chip is immersed in the antioxidant solution for 2 minutes to form an antioxidant protective layer on the surface of the copper electrode layer on both sides of the ceramic chip. The antioxidant protective layer is then subjected to infrared irradiation and drying treatment, wherein the radiation power of the infrared irradiation is 400mw and the infrared irradiation time is 2h, thereby obtaining a ceramic chip with a composite electrode; by immersing in the antioxidant solution, a uniform and dense protective film can be formed on the surface of the copper electrode layer to prevent the copper electrode layer from contacting with oxygen, moisture or other corrosive substances in the air during use, thereby extending the service life of the ceramic chip; by irradiating the antioxidant protective layer with infrared rays, the moisture in the antioxidant protective layer can be evaporated in a relatively short time, thereby forming a uniform and firm antioxidant protective layer; in this embodiment, the ceramic chip is used for ceramic capacitors.

[0050] The preparation method of the antioxidant solution is as follows: dissolve 2-methylbenzimidazole in a formic acid solution, adjust the pH value to 3, so that 2-methylbenzimidazole is completely dissolved to obtain an antioxidant solution; the concentration of 2-methylbenzimidazole is 0.3 mol / L, and the concentration of formic acid is 0.1 mol / L. 2-methylbenzimidazole can form a stable film on the surface of the copper electrode layer to prevent copper from contacting oxygen, moisture and other corrosive gases in the air, thereby reducing oxidation and corrosion; specifically, the imidazole ring structure in 2-methylbenzimidazole can be combined with the copper surface through chemical bonding to form a strong, stable and dense protective layer; formic acid, as a solvent, can effectively dissolve 2-methylbenzimidazole and provide an acidic environment in the solution to promote the combination of 2-methylbenzimidazole and the copper electrode layer.

[0051] Example 2

[0052] like Figure 1 and Figure 2 As shown, the embodiment of the present invention provides a process for preparing a composite electrode for a ceramic chip, comprising the following steps:

[0053] S1. Place the cleaned ceramic chip in a clamping fixture 10, and expose the spraying surfaces at both ends of the ceramic chip to the clamping fixture 10, wherein the clamping fixture 10 includes a carrier plate 11, a first clamping plate 12 and a second clamping plate 13, the carrier plate 11 is provided with an array of positioning holes 110, the shape of the positioning holes 110 is adapted to the shape of the ceramic chip, the positioning holes 110 are used to position and place the ceramic chip to be sprayed, the first clamping plate 12 and the second clamping plate 13 are respectively arranged on the front and rear sides of the carrier plate 11, the first clamping plate 12 and the second clamping plate 13 are locked and connected by bolts 14, the first clamping plate 12 and the second clamping plate 13 are provided with spraying avoidance holes 120 corresponding to the positions of the positioning holes 110, the area of ​​the spraying avoidance holes 120 is less than or equal to the area of ​​the positioning holes 110, and the spraying avoidance holes 120 are used for spraying droplets onto the spraying surface of the ceramic chip;

[0054] S2, the fixture 10 with the ceramic chip clamped is hung on the chain conveyor 20 by a hook, and a first station 201 and a second station 202 are arranged along the conveying direction of the chain conveyor 20, two first electrode spray guns 31 are arranged on the front and rear sides of the first station 201, and two second electrode spray guns 32 are arranged on the front and rear sides of the second station 202, and the conveying speed of the chain conveyor 20 is 4m / min;

[0055] S3, the chain conveyor 20 drives the clamping fixture 10 to move, and when the ceramic chip moves to the first station 201, the first electrode spray gun 31 is used to thermally spray the aluminum electrode material onto the two spraying surfaces of the ceramic chip to form an aluminum electrode layer on the spraying surface of the ceramic chip, and the thickness of the aluminum electrode layer is 10 μm;

[0056] S4. After the spraying of the aluminum electrode layer is completed, the chain conveyor 20 drives the clamping fixture 10 to continue to move. When the ceramic chip moves to the second station 202, the second electrode spray gun 32 is used to cover the copper electrode material on the surface of the aluminum electrode layer by thermal spraying to form a copper electrode layer. The thickness of the copper electrode layer is 5 μm.

[0057] The spray gun nozzles of the first electrode spray gun 31 and the second electrode spray gun 32 are arranged facing the front and back of the clamping fixture 10; and the first electrode spray gun 31 and the second electrode spray gun 32 are respectively connected to the double-axis moving mechanism 40 to adjust the positions of the first electrode spray gun 31 and the second electrode spray gun 32;

[0058] The biaxial moving mechanism 40 includes a lifting and moving module 41 and a horizontal moving module 42. The lifting and moving module 41 is used to adjust the height of the first electrode spray gun 31 and the second electrode spray gun 32 so that the sprayed molten droplets are covered and deposited on the sprayed surfaces of all ceramic chips. The horizontal moving module 42 is used to adjust the horizontal distance between the first electrode spray gun 31 and the second electrode spray gun 32 relative to the ceramic chip to control the deposition rate of the sprayed molten droplets.

[0059] During the spraying process, the movement rate of the lifting and moving module 41 is 30 mm / s; when spraying, the second electrode spray gun 32 uses nitrogen as compressed gas to atomize and spray the melted spray droplets onto the surface of the aluminum electrode layer of the ceramic chip;

[0060] The aluminum electrode material and the copper electrode material are of an alloy wire structure. The first electrode spray gun 31 and the second electrode spray gun 32 melt the aluminum electrode material or the copper electrode material of the alloy wire structure by arc spraying and spray them on the ceramic chip; wherein the spraying parameters of the first electrode spray gun 31 and the second electrode spray gun 32 are: spraying voltage of 40V, spraying current of 200A, spraying gas pressure of 0.5Mpa, gas flow rate of 10L / min, wire feeding voltage of 10V, wire feeding rate of 0.8m / min, and spraying distance of 150mm.

[0061] S5. After the clamping fixture 10 is taken out from the chain conveyor 20, it is also immersed in an antioxidant solution for antioxidant treatment. The ceramic chip is immersed in the antioxidant solution for 10 minutes to form an antioxidant protective layer on the surface of the copper electrode layer on both sides of the ceramic chip. The antioxidant protective layer is then subjected to infrared irradiation and drying treatment, wherein the radiation power of the infrared irradiation is 750mw and the infrared irradiation time is 1h, thereby obtaining a ceramic chip with a composite electrode. In this embodiment, the ceramic chip is used for a varistor.

[0062] The preparation method of the antioxidant solution is: dissolving 2-methylbenzamidazole in a formic acid solution, adjusting the pH value to 5 so that the 2-methylbenzamidazole is completely dissolved, and obtaining the antioxidant solution, wherein the concentration of the 2-methylbenzamidazole is 0.4 mol / L, and the concentration of the formic acid is 0.2 mol / L.

[0063] Comparative Example 1

[0064] The preparation process of the composite electrode for ceramic chips in Comparative Example 1 is different from that in Example 1 in that the second electrode spray gun uses air as compressed gas to atomize and spray the melted spray droplets onto the surface of the aluminum electrode layer of the ceramic chip during spraying.

[0065] Comparative Example 2

[0066] The preparation process of the composite electrode for ceramic chips in Comparative Example 2 is different from that in Example 1 in that the spraying distances of the first electrode spray gun and the second electrode spray gun are 420 mm.

[0067] Comparative Example 3

[0068] The preparation process of the composite electrode for ceramic chips in Comparative Example 3 is different from that in Example 1 in that the ceramic chips are not immersed in an antioxidant solution for antioxidant treatment.

[0069] Comparative Example 4

[0070] The preparation process of the composite electrode for ceramic chips in Comparative Example 4 is different from that in Example 1 in that after the ceramic chips are immersed in the antioxidant solution, the antioxidant protective layer is solidified by natural cooling.

[0071] Comparative Example 5

[0072] The preparation process of the composite electrode for ceramic chips in Comparative Example 5 is different from that in Example 2 in that only the copper electrode layer is sprayed on both sides of the ceramic chip.

[0073] The ceramic chips prepared in Examples 1-2 and Comparative Examples 1-5 were sampled for performance testing and the oxidation phenomenon was observed after 24 hours. The results are shown in the following table.

[0074] Sample No. Resistance (Ω) Is it oxidized? Adhesion between copper electrode layer and ceramic chip Example 1 11.3 no good Example 2 10.8 no good Comparative Example 1 15.6 yes generally Comparative Example 2 11.2 no Poor Comparative Example 3 12.4 yes Poor Comparative Example 4 11.7 yes generally Comparative Example 5 10.4 no good

[0075] Table 1 Comparison of ceramic chip performance of each embodiment and comparative example

[0076] It can be seen from the above table that the ceramic chip with composite electrodes prepared by the present invention has good conductivity, high stability, good electrode adhesion, and can effectively prevent oxidation of the copper electrode layer.

[0077] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing a composite electrode for a ceramic chip, characterized in that: The following steps are involved: S1. Place the cleaned ceramic chip in a fixture, and expose the sprayed surfaces at both ends of the ceramic chip to the fixture; S2, hanging the clamping fixture with the ceramic chip on the chain conveyor, configuring a first station and a second station along the conveying direction of the chain conveyor, two first electrode spray guns are configured on the front and rear sides of the first station, and two second electrode spray guns are configured on the front and rear sides of the second station; S3, the chain conveyor device drives the clamping fixture to move, and when the ceramic chip moves to the first station, the first electrode spray gun is used to thermally spray the aluminum electrode material onto the two spraying surfaces of the ceramic chip to form an aluminum electrode layer on the spraying surface of the ceramic chip; S4. After the spraying of the aluminum electrode layer is completed, the chain conveyor device drives the clamping fixture to continue to move. When the ceramic chip moves to the second station, the copper electrode material is thermally sprayed on the surface of the aluminum electrode layer using the second electrode spray gun to form a copper electrode layer. The second electrode spray gun uses nitrogen as compressed gas to atomize and spray the melted spray droplets onto the surface of the aluminum electrode layer of the ceramic chip during spraying. S5. Take the clamping fixture out from the chain conveyor to obtain a ceramic chip with a composite electrode.

2. The process for preparing a composite electrode for a ceramic chip according to claim 1, characterized in that: In step S5, after the clamping fixture is taken out from the chain conveyor, it is also immersed in an antioxidant solution for antioxidant treatment to form an antioxidant protective layer on the surface of the copper electrode layer on both sides of the ceramic chip; The immersion time of the ceramic chip in the antioxidant solution is 2-10 minutes. The preparation method of the antioxidant solution is: dissolving 2-methylbenzamidazole in a formic acid solution, adjusting the pH value to 3-5 to completely dissolve the 2-methylbenzamidazole, and obtaining the antioxidant solution.

3. The process for preparing a composite electrode for a ceramic chip according to claim 3, characterized in that: In the antioxidant solution, the concentration of 2-methylbenzimidazole is 0.3-0.4 mol / L, and the concentration of formic acid is 0.1-0.2 mol / L.

4. The process for preparing a composite electrode for a ceramic chip according to claim 3, characterized in that: After the soaking is completed, the anti-oxidation protective layer is subjected to infrared irradiation and drying treatment, wherein the infrared irradiation radiation power is 400-750mw and the infrared irradiation time is 1-2h.

5. The process for preparing a composite electrode for a ceramic chip according to claim 1, characterized in that: The aluminum electrode material and the copper electrode material are alloy wire structures; The first electrode spray gun and the second electrode spray gun melt the aluminum electrode material or the copper electrode material of the alloy wire structure and spray it on the ceramic chip by arc spraying; Among them, the spraying parameters of the first electrode spray gun and the second electrode spray gun are: spraying voltage is 32-40V, spraying current is 100-200A, spraying gas pressure is 0.5-0.8Mpa, gas flow rate is 10-30L / min, wire feeding voltage is 10-15V, wire feeding rate is 0.8-1.2m / min, and spraying distance is 150-260mm.

6. The process for preparing a composite electrode for a ceramic chip according to claim 1, characterized in that: The thickness of the aluminum electrode layer is 10-80 μm, and the thickness of the copper electrode layer is 5-25 μm.

7. The process for preparing a composite electrode for a ceramic chip according to claim 1, characterized in that: The clamping fixture comprises a carrier plate, a first clamping plate and a second clamping plate; The carrier plate is provided with positioning holes arranged in an array, the shape of the positioning holes is adapted to the shape of the ceramic chip, and the positioning holes are used to position and place the ceramic chip to be sprayed; The first clamping plate and the second clamping plate are respectively arranged on the front and rear sides of the material carrying plate, and the first clamping plate and the second clamping plate are locked and connected by bolts; The first clamping plate and the second clamping plate are provided with spray avoidance holes corresponding to the positions of the positioning holes, the area of ​​the spray avoidance holes is less than or equal to the area of ​​the positioning holes, and the spray avoidance holes are used for allowing spray droplets to be sprayed onto the spraying surface of the ceramic chip.

8. The process for preparing a composite electrode for a ceramic chip according to claim 1, characterized in that: In step S3 and step S4, the spray gun nozzles of the first electrode spray gun and the second electrode spray gun are arranged facing the front and back of the clamping fixture; and the first electrode spray gun and the second electrode spray gun are respectively connected to the double-axis moving mechanism to adjust the positions of the first electrode spray gun and the second electrode spray gun; The biaxial moving mechanism includes a lifting and moving module and a horizontal moving module. The lifting and moving module is used to adjust the height of the first electrode spray gun and the second electrode spray gun so that the sprayed molten droplets are covered and deposited on the spraying surfaces of all ceramic chips. The horizontal moving module is used to adjust the horizontal distance between the first electrode spray gun and the second electrode spray gun relative to the ceramic chip to control the deposition rate of the sprayed molten droplets. Among them, during the spraying process, the movement rate of the lifting and moving module is 10-30mm / s.

9. The process for preparing a composite electrode for a ceramic chip according to claim 1, characterized in that: The clamping fixture is connected to the chain conveying device through a hook; The conveying speed of the chain conveyor is 2-4 m / min.

10. The process for preparing a composite electrode for a ceramic chip according to any one of claims 1 to 9, characterized in that: The ceramic chip is any one of a varistor, a thermistor or a ceramic capacitor.

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