Preparation process of ceramic capacitive pressure sensor electrode film

Abstract

The invention provides a preparation process of a ceramic capacitive pressure sensor electrode film, and relates to the field of electronic ceramics. The preparation process of the ceramic capacitive pressure sensor electrode film comprises the following steps: S1, selecting a ceramic substrate; s2, polishing the ceramic matrix; s3, cleaning: completely immersing the ceramic matrix in an alcohol solution, and then fully washing the ceramic matrix with deionized water; s4, activating: preparing an activating solution according to the mass ratio of stannic chloride to silver nitrate to hydrochloric acid to sodium acetate being 4: 3: 0.2: 0.2, and then cleaning with deionized water. S5, preparing a composite layer, preparing a plating solution in three times, and sequentially adding main salt, a complexing agent, a reducing agent, a stabilizing agent, deionized water and a pH regulator; a chemical plating process is introduced into the field of sensor electrode preparation, the idea of traditional physical method electrode preparation is broken through, a composite coating and multiple different types of coatings are adopted for mixed processing, the coating type is controllable, operation is easy, equipment is simple, and the cost is controllable.

Description

Technical Field

[0001] The invention relates to the technical field of electronic ceramics, and in particular to a preparation process of a ceramic capacitive pressure sensor electrode film. Background Art

[0002] Ceramic capacitive pressure sensors are made by using advanced electronic ceramic technology, integrated circuit technology and thick film planar circuit technology, and are made by using precision ceramic sealing technology. Compared with traditional pressure sensors, they have excellent high temperature resistance, corrosion resistance, wear resistance, high sensitivity and strong anti-interference ability. It is particularly worth noting that they have strong impact resistance and overload resistance, and are small in size. Such sensors are widely used in the automotive field, commercial air conditioning and energy storage field, industrial process control field, aerospace and military field. At present, the domestic market is mainly monopolized by foreign companies such as Kavlico and Sensata, and the price is expensive. China is relatively backward in both manufacturing technology and process materials. The main problems are: poor high temperature stability of capacitor electrodes, the electrodes are easy to lose their conductive properties after high temperature welding, the conductive film layer is too thin, the adhesion to the ceramic substrate is too low, and it is easy to fall off during use.

[0003] The existing patent discloses a method for metallizing the surface of an aluminum oxide or aluminum nitride ceramic substrate (publication number: CN108598007A). The patent discloses a method for metallizing the surface of an aluminum oxide or aluminum nitride ceramic substrate. The patent uses a mask to cover the upper and lower surfaces of the aluminum oxide or aluminum nitride ceramic substrate after cleaning, and sputters in a sputtering chamber to complete the metallization of the surface of the aluminum oxide or aluminum nitride ceramic substrate in one step.

[0004] The existing patent discloses a method for direct metallization of ceramic substrates (CN105801179B). The steps are briefly as follows: 1) pre-treating the ceramic substrate; 2) chemically plating nickel on the ceramic substrate after pre-treatment; 3) oxidizing the nickel layer on the ceramic substrate after chemical nickel plating; 4) flash-plating a fresh nickel layer on the ceramic substrate with the nickel oxide layer; 5) electroplating copper on the fresh nickel layer;

[0005] The existing patent also discloses a method for metallizing a ceramic surface and a metallized ceramic (publication number: CN114163259B). The preparation method thereof comprises: irradiating a ceramic substrate with a laser beam to write a circuit pattern area on the ceramic substrate; immersing the irradiated ceramic substrate in a copper plating solution for chemical copper plating to grow a seed copper layer on the circuit pattern area; placing solder and copper foil on the seed copper layer in sequence for brazing; etching to expose the ceramic substrate in the non-circuit pattern area;

[0006] The existing patent also discloses a preparation process suitable for copper metallization on the surface of alumina ceramics (publication number: CN105367128B). The preparation steps include the following specific steps: preparing paste, screen printing, sintering, and secondary sintering. Through the above method, the preparation process suitable for copper metallization on the surface of alumina ceramics provided by the present invention integrates the two copper coating processes in the prior art, and develops a low-cost ceramic copper coating method similar to the thick film process. The required circuit diagram is printed on the surface of the ceramic part by thick film printing, and then the copper layer is obtained by air sintering and hydrogen reduction. The obtained copper layer has similar performance to the copper layer manufactured by the DBC process, and the bonding strength is higher than the traditional copper thick film method, while avoiding the high requirements of the DBC process on equipment and secondary chemical or laser etching of the copper-clad plate. The above-mentioned patent has the following disadvantages: for the use of magnetron sputtering The metallization modification of the ceramic substrate surface is achieved by the spraying process. The equipment of this method is expensive and the operation is complicated. The bonding strength between the coating and the ceramic substrate is low. For the chemical plating combined with electroplating composite plating process, the process is high-temperature oxidation after the nickel layer is plated, and then a layer of nickel is flash-plated and then copper is electroplated. This process involves the bonding strength of the plating layers, and the bonding strength between the electroplated copper layer and the flash-plated nickel layer cannot be guaranteed. For the chemical plating combined with brazing process, this process uses chemical plating as a backdrop to prepare copper seeds, and brazing is used to induce coating thickening. The principle of this process is to use brazing technology to induce the growth of copper seeds, but the growth trend cannot be guaranteed, and the density and bonding strength of the coating cannot be guaranteed.

[0007] At present, the methods for preparing ceramic electrode films can be generally summarized into two categories: physical method and chemical method. The physical method mainly includes magnetron sputtering and vacuum evaporation, and the chemical method mainly includes sol-gel method and chemical plating. Among them, the physical method has a relatively high production cost, high requirements on equipment, and the operation requires professionals, and the technical threshold is high. The chemical method has a low manufacturing cost, simple operation, no requirements on equipment, suitable for large-scale production, and easy to form assembly line production. However, there are very few publicly reported materials on electrodes prepared by chemical plating process for ceramic capacitive pressure sensors. Therefore, technicians in this field provide a preparation process for ceramic capacitive pressure sensor electrode films to solve the problems raised in the above background technology. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] In view of the shortcomings of the prior art, the present invention provides a process for preparing a ceramic capacitive pressure sensor electrode film, which solves the problems of relatively high production cost, high equipment requirements, and the need for professional personnel to operate, and high technical threshold.

[0010] (II) Technical solution

[0011] To achieve the above objectives, the present invention is implemented by the following technical scheme: A process for preparing a ceramic capacitive pressure sensor electrode film, comprising the following steps:

[0012] S1. Select a ceramic substrate, including but not limited to alumina, aluminum nitride and silicon nitride;

[0013] S2. polishing the ceramic substrate;

[0014] S3. Cleaning, the ceramic substrate is placed in an alcohol container, completely immersed in the solution, ultrasonically vibrated for 5 to 20 minutes at a temperature of 30 to 50 degrees Celsius, and then fully rinsed with deionized water;

[0015] S4 activation, configuration activation solution, mass ratio of tin chloride: silver nitrate: hydrochloric acid: sodium acetate = 4:3:0.2:0.2, the ceramic substrate after step S3 was activated, the concentration used was 10g / L to 100g / L, soaked for 5 to 10 minutes, and then washed with deionized water;

[0016] S5. Preparation of nickel layer, preparation of plating solution, sequentially adding main salt, complexing agent, reducing agent, stabilizer, deionized water, pH adjusting agent, the main salt is nickel sulfate, nickel acetate, nickel nitrate concentration is 10g / L to 50g / L; complexing agent is sodium citrate, glycine, ammonia water, one or two, concentration is 5g / L to 20g / L, reducing agent is sodium hypophosphite, sodium borohydride, hydrazine, concentration is 10g / L to 20g / L, stabilizer is ammonium chloride, thiourea, sodium thiosulfate, one or more, concentration is 5mg / L to 20mg / L, deionized water, pH adjusting agent, the plating solution pH is adjusted to 10 to 13;

[0017] S6. The ceramic substrate treated in step S4 is placed in the plating solution prepared in step S5, heated in a water bath, the temperature is controlled at 50 to 70 degrees Celsius, the plating solution is slowly stirred during the reaction, the reaction time should be controlled at 5 to 8 minutes, the ceramic substrate is removed and cleaned and then vacuum dried at 80 degrees Celsius;

[0018] S7 copper layer preparation, the ceramic substrate treated in step S6 is placed in the activation solution prepared in step S4 at a concentration of 10g / L to 100g / L, soaked for 5 to 10 minutes, and then washed with deionized water;

[0019] S8. Prepare a plating solution, add a main salt, a complexing agent, a reducing agent, a stabilizer, deionized water and a pH adjuster in sequence, wherein the main salt is copper sulfate, copper chloride or copper nitrate, and the concentration is 10g / L to 30g / L; the complexing agent is one or two of potassium sodium tartrate, tartaric acid, and EDTA-2Na, and the concentration is 10g / L to 60g / L, the reducing agent is formaldehyde, glyoxylic acid, and the concentration is 1mL / L to 10mL / L, the stabilizer is sodium sulfite, sodium acetate, alkylbenzene sulfonate, one or more, and the concentration is 5mg / L to 10mg / L, some deionized water, pH adjuster, the pH of the plating solution is adjusted to 10 to 12;

[0020] S9. The ceramic substrate treated in step S7 is placed in the prepared plating solution in step S8, heated in a water bath, the temperature is controlled at 45 to 75 degrees Celsius, the plating solution is slowly stirred during the reaction, the reaction time should be controlled at 3 to 6 minutes, the ceramic substrate is removed and cleaned and then dried in vacuum at 80 degrees Celsius;

[0021] S10 gold layer preparation, the ceramic substrate after step S9 is placed in the activation solution prepared in step S4, the concentration used is 10g / L to 100g / L, soak for 5 to 10 minutes, and then rinse with deionized water;

[0022] S11. Prepare a plating solution, add a main salt, a complexing agent, a reducing agent, a stabilizer, deionized water and a pH adjuster in sequence, wherein the main salt is gold cyanide, potassium gold cyanide or potassium gold chloride trihydrate, and the concentration is 5g / L to 40g / L; the complexing agent is one or both of sodium cyanide or potassium cyanide, and the concentration is 10g / L to 40g / L; the reducing agent is glucose, sucrose or sodium hypophosphite, and the concentration is 5g / L to 10g / L; the stabilizer is one or more of ethanolamine and EDTA-2Na, and the concentration is 2mg / L to 8mg / L; some deionized water, pH adjuster, adjust the pH of the plating solution to 10 to 11;

[0023] S12. Place the ceramic substrate treated in step S10 in the plating solution prepared in step S11, heat it in a water bath, control the temperature at 60 to 75 degrees Celsius, slowly stir the plating solution during the reaction, and the reaction time should be controlled at 5 to 10 minutes. Take out the ceramic substrate, clean it, and then dry it at 80 degrees Celsius in a vacuum, thus completing the preparation of the ceramic capacitive pressure sensor electrode film.

[0024] (III) Beneficial effects

[0025] The present invention provides a process for preparing a ceramic capacitive pressure sensor electrode film, which has the following beneficial effects:

[0026] 1. In the present invention, by introducing the chemical plating process into the field of sensor electrode preparation, the idea of ​​preparing electrodes by traditional physical methods is broken, the coating type is controllable, easy operation is achieved, the equipment is simple, the cost is controllable, the chemical plating reaction is stable, the coating quality is controllable, composite plating can be achieved, the coating bonding force is strong, the cost of chemical plating is controllable, the cycle is short, and it is easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall process of the preparation process of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1:

[0030] like Figure 1 As shown, an embodiment of the present invention provides a process for preparing a ceramic capacitive pressure sensor electrode film, comprising the following steps:

[0031] S1. Select a ceramic substrate, including but not limited to alumina, aluminum nitride and silicon nitride;

[0032] S2. polishing the ceramic substrate;

[0033] S3. Cleaning, the ceramic substrate is placed in an alcohol container, completely immersed in the solution, ultrasonically vibrated for 5 to 20 minutes at a temperature of 30 to 50 degrees Celsius, and then fully rinsed with deionized water;

[0034] S4 activation, configuration activation solution, mass ratio of tin chloride: silver nitrate: hydrochloric acid: sodium acetate = 4:3:0.2:0.2, the ceramic substrate after step S3 was activated, the concentration used was 10g / L to 100g / L, soaked for 5 to 10 minutes, and then washed with deionized water;

[0035] S5. Preparation of nickel layer, preparation of plating solution, sequentially adding main salt, complexing agent, reducing agent, stabilizer, deionized water, pH adjusting agent, main salt is nickel sulfate, nickel acetate, nickel nitrate concentration is 10g / L to 50g / L; complexing agent is sodium citrate, glycine, ammonia water, one or two, concentration is 5g / L to 20g / L, reducing agent is sodium hypophosphite, sodium borohydride, hydrazine, concentration is 10g / L to 20g / L, stabilizer is ammonium chloride, thiourea, sodium thiosulfate, one or more, concentration is 5mg / L to 20mg / L, deionized water, pH adjusting agent, the plating solution pH is adjusted to 10 to 13;

[0036] S6. The ceramic substrate treated in step S4 is placed in the plating solution prepared in step S5, heated in a water bath, the temperature is controlled at 50 to 70 degrees Celsius, the plating solution is slowly stirred during the reaction, the reaction time should be controlled at 5 to 8 minutes, the ceramic substrate is removed and cleaned and then vacuum dried at 80 degrees Celsius;

[0037] S7 copper layer preparation, the ceramic substrate treated in step S6 is placed in the activation solution prepared in step S4 at a concentration of 10g / L to 100g / L, soaked for 5 to 10 minutes, and then washed with deionized water;

[0038] S8. Prepare a plating solution, add the main salt, complexing agent, reducing agent, stabilizer, deionized water and pH adjuster in sequence, the main salt is copper sulfate, copper chloride or copper nitrate, the concentration is 10g / L to 30g / L; the complexing agent is potassium sodium tartrate, tartaric acid, EDTA-2Na, one or two of them, the concentration is 10g / L to 60g / L, the reducing agent is formaldehyde, glyoxylic acid, the concentration is 1mL / L to 10mL / L, the stabilizer is sodium sulfite, sodium acetate, alkylbenzene sulfonate, one or more of them, the concentration is 5mg / L to 10mg / L, deionized water, some, pH adjuster, the pH of the plating solution is adjusted to 10 to 12;

[0039] S9. The ceramic substrate treated in step S7 is placed in the prepared plating solution in step S8, heated in a water bath, the temperature is controlled at 45 to 75 degrees Celsius, the plating solution is slowly stirred during the reaction, the reaction time should be controlled at 3 to 6 minutes, the ceramic substrate is removed and cleaned and then dried in vacuum at 80 degrees Celsius;

[0040] S10 gold layer preparation, the ceramic substrate after step S9 is placed in the activation solution prepared in step S4, the concentration used is 10g / L to 100g / L, soak for 5 to 10 minutes, and then rinse with deionized water;

[0041] S11. Prepare a plating solution, add the main salt, complexing agent, reducing agent, stabilizer, deionized water and pH regulator in sequence, the main salt is gold cyanide, potassium gold cyanide or potassium gold chloride trihydrate, the concentration is 5g / L to 40g / L; the complexing agent is one or both of sodium cyanide or potassium cyanide, the concentration is 10g / L to 40g / L, the reducing agent is glucose, sucrose or sodium hypophosphite, the concentration is 5g / L to 10g / L, the stabilizer is one or more of ethanolamine and EDTA-2Na, the concentration is 2mg / L to 8mg / L, some deionized water, pH regulator, adjust the pH of the plating solution to 10 to 11;

[0042] S12. Place the ceramic substrate treated in step S10 in the plating solution prepared in step S11, heat it in a water bath, control the temperature at 60 to 75 degrees Celsius, slowly stir the plating solution during the reaction, and the reaction time should be controlled at 5 to 10 minutes. Take out the ceramic substrate, clean it, and then dry it at 80 degrees Celsius in a vacuum, thus completing the preparation of the ceramic capacitive pressure sensor electrode film.

[0043] Embodiment 2:

[0044] S1. Assemble the mask plate on the ceramic substrate according to the electrode pattern required by the sensor, and expose the side where the electrode pattern needs to be prepared;

[0045] S2. polishing the ceramic substrate;

[0046] S3. Cleaning: Place the ceramic substrate in an alcohol container, immerse it completely in the solution, vibrate ultrasonically for 5 minutes at a temperature of 30°C, and rinse thoroughly with deionized water;

[0047] S4 activation: configuration activation solution, mass ratio of tin chloride: silver nitrate: hydrochloric acid: sodium acetate = 4:3:0.2:0.2, the S3 treated ceramic substrate was activated, the concentration used was 10g / L, soaked for 5min, and then washed with deionized water;

[0048] S5. Prepare the plating solution: sequentially add nickel sulfate at a concentration of 10 g / L, sodium citrate at a concentration of 5 g / L, sodium phosphite at a concentration of 10 g / L, ammonium chloride at a concentration of 5 mg / L, deionized water, and a pH regulator to adjust the pH of the plating solution to 10.2;

[0049] S6. Place the ceramic substrate treated by S4 in the plating solution prepared by S5, heat it in a water bath, control the temperature at 50°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 5 minutes. Take out the ceramic substrate, clean it, and dry it at 80°C in a vacuum oven;

[0050] S7. The ceramic substrate treated with S6 was placed in the activation solution prepared in S4 at a concentration of 10 g / L, soaked for 5 min, and then washed with deionized water;

[0051] S8. Prepare the plating solution: add copper sulfate at a concentration of 10 g / L, potassium sodium tartrate at a concentration of 10 g / L, formaldehyde at a concentration of 1 mL / L, sodium sulfite at a concentration of 5 mg / L, deionized water, and a pH adjuster to adjust the pH of the plating solution to 10.7;

[0052] S9. Place the ceramic substrate treated in S7 in the plating solution prepared in S8, heat in a water bath, control the temperature at 45°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 3 minutes. Take out the ceramic substrate, clean it, and dry it at 80°C in a vacuum oven;

[0053] S10. The ceramic substrate treated with S9 was placed in the activation solution prepared in S4 at a concentration of 10 g / L, soaked for 5 min, and then washed with deionized water;

[0054] S11. Prepare the plating solution: add gold cyanide at a concentration of 5 g / L, sodium cyanide at a concentration of 10 g / L, glucose at a concentration of 5 g / L, ethanolamine at a concentration of 2 mg / L, some ionized water, and a pH adjuster to adjust the pH of the plating solution to 10;

[0055] S12. Place the ceramic substrate treated in S10 in the plating solution prepared in S11, heat it in a water bath, control the temperature at 60°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 5 minutes. Take out the ceramic substrate, clean it, and dry it at 80°C in a vacuum oven. The preparation of the ceramic capacitive pressure sensor electrode film is now completed.

[0056] Embodiment three:

[0057] S1. Assemble the mask plate on the ceramic substrate according to the electrode pattern required by the sensor, and expose the side where the electrode pattern needs to be prepared;

[0058] S2. polishing the ceramic substrate;

[0059] S3. Cleaning: Place the ceramic substrate in an alcohol container, immerse it completely in the solution, vibrate ultrasonically for 15 minutes at 40°C, and rinse thoroughly with deionized water;

[0060] S4 activation: configuration activation solution, mass ratio of tin chloride: silver nitrate: hydrochloric acid: sodium acetate = 4:3:0.2:0.2, the S3 treated ceramic substrate was activated, the concentration used was 50g / L, soaked for 8min, and then washed with deionized water;

[0061] S5. Prepare the plating solution: sequentially add nickel acetate at a concentration of 25 g / L, glycine at a concentration of 10 g / L, sodium borohydride at a concentration of 15 g / L, thiourea at a concentration of 10 mg / L, deionized water, and a pH regulator to adjust the pH of the plating solution to 11;

[0062] S6. Place the ceramic substrate treated by S4 in the plating solution prepared by S5, heat it in a water bath, control the temperature at 60°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 6 minutes. Take out the ceramic substrate, clean it, and dry it at 80°C in a vacuum oven;

[0063] S7. The ceramic substrate treated with S6 was placed in the activation solution prepared in S4 at a concentration of 50 g / L, soaked for 8 min, and then washed with deionized water;

[0064] S8. Prepare the plating solution: add copper chloride at a concentration of 20 g / L, tartaric acid at a concentration of 30 g / L, glyoxylic acid at a concentration of 5 mL / L, sodium acetate at a concentration of 8 mg / L, deionized water, and a pH regulator to adjust the pH of the plating solution to 11;

[0065] S9. Place the ceramic substrate treated in S7 in the plating solution prepared in S8, heat in a water bath, control the temperature at 60°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 5 minutes. Take out the ceramic substrate, clean it, and dry it in a vacuum oven at 80°C.

[0066] S10. The ceramic substrate treated with S9 was placed in the activation solution prepared in S4 at a concentration of 50 g / L, soaked for 8 min, and then washed with deionized water;

[0067] S11. Prepare the plating solution: sequentially add potassium gold cyanide at a concentration of 20 g / L, potassium cyanide at a concentration of 20 g / L, sucrose at a concentration of 8 g / L, EDTA-2Na at a concentration of 5 mg / L, some ionized water, and a pH adjuster to adjust the pH of the plating solution to 10.5;

[0068] S12. Place the ceramic substrate treated in S10 in the plating solution prepared in S11, heat it in a water bath, control the temperature at 70°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 8 minutes. Take out the ceramic substrate, clean it, and dry it in a vacuum oven at 80°C. The preparation of the electrode film of the ceramic capacitive pressure sensor is completed.

[0069] Embodiment 4:

[0070] S1. Assemble the mask plate on the ceramic substrate according to the electrode pattern required by the sensor, and expose the side where the electrode pattern needs to be prepared;

[0071] S2. polishing the ceramic substrate;

[0072] S3. Cleaning: Place the ceramic substrate in an alcohol container, immerse it completely in the solution, vibrate ultrasonically for 20 minutes at 50°C, and rinse thoroughly with deionized water;

[0073] S4 activation: configure the activation solution, the mass ratio of tin chloride: silver nitrate: hydrochloric acid: sodium acetate = 4:3:0.2:0.2, the S3 treated ceramic substrate was activated at a concentration of 100g / L, soaked for 10min, and then washed with deionized water;

[0074] S5. Prepare the plating solution: sequentially add nickel nitrate at a concentration of 50 g / L, ammonia at a concentration of 20 g / L, hydrazine at a concentration of 20 g / L, sodium thiosulfate at a concentration of 20 mg / L, deionized water, and a pH regulator to adjust the pH of the plating solution to 12;

[0075] S6. Place the ceramic substrate treated by S4 in the plating solution prepared by S5, heat it in a water bath, control the temperature at 70°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 8 minutes. Take out the ceramic substrate, clean it, and dry it at 80°C in a vacuum oven;

[0076] S7. The ceramic substrate treated with S6 was placed in the activation solution prepared in S4 at a concentration of 100 g / L, soaked for 10 min, and then washed with deionized water;

[0077] S8. Prepare the plating solution: add copper nitrate at a concentration of 30 g / L, EDTA-2Na at a concentration of 60 g / L, hydrazine at a concentration of 10 mL / L, sodium alkylbenzene sulfonate at a concentration of 10 mg / L, deionized water, and a pH adjuster to adjust the pH of the plating solution to 12;

[0078] S9. Place the ceramic substrate treated in S7 in the plating solution prepared in S8, heat in a water bath, control the temperature at 75°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 56 minutes. Take out the ceramic substrate, clean it, and dry it at 80°C in a vacuum oven;

[0079] S10. The ceramic substrate treated with S9 was placed in the activation solution prepared in S4 at a concentration of 100 g / L, soaked for 10 min, and then washed with deionized water;

[0080] S11. Prepare the plating solution: sequentially add potassium gold chloride trihydrate at a concentration of 40 g / L, potassium cyanide at a concentration of 40 g / L, sodium hypophosphite at a concentration of 10 g / L, EDTA-2Na at a concentration of 8 mg / L, some ionized water, and a pH adjuster to adjust the pH of the plating solution to 11;

[0081] S12. Place the ceramic substrate treated in S10 in the plating solution prepared in S11, heat it in a water bath, control the temperature at 75°C, slowly stir the plating solution during the reaction, and the reaction time should be controlled within 10 minutes. Take out the ceramic substrate, clean it, and dry it in a vacuum oven at 80°C. The preparation of the ceramic capacitive pressure sensor electrode film is completed.

[0082] Comparative Example 1:

[0083] The activation step before each plating was removed, and the remaining steps were the same as in Example 2. It was finally concluded that no effective coating was deposited on the surface of the ceramic substrate, which was intended to illustrate that the activation step was crucial.

[0084] Comparative Example 2:

[0085] The step of applying the nickel layer as the base layer is removed, and the remaining steps are the same as those in Example 2. Finally, it is concluded that the bonding force between the ceramic substrate and the coating is poor, and the coating is easy to fall off, indicating that the nickel layer as the base layer can enhance the bonding force between the coating and the ceramic substrate, and its preparation process is crucial;

[0086] Comparative Example 3:

[0087] The copper layer of the transition layer is removed, and the remaining steps are the same as those of Example 2. It is finally concluded that the conductive layer cannot be buffered due to excessive internal stress, and the conductive layer is directly connected to the base layer without a transition layer, resulting in peeling and damage on the surface of the conductive layer coating, and the conductivity is reduced, indicating that the preparation of the transition layer is crucial;

[0088] Comparative Example 4:

[0089] The gold layer of the conductive layer is removed, and the remaining steps are the same as in Example 2. Finally, it is concluded that since there is no conductive layer deposited on the ceramic substrate, the electrical signal cannot be transmitted well, which affects the linear output and sensitivity of the sensor, indicating that the preparation process of the conductive layer is crucial;

[0090] Thermal shock test:

[0091] Test equipment: hot and cold shock test chamber;

[0092] Test materials: Examples 2-4 and Comparative Examples 2-4, a total of 6 pieces of coated ceramics;

[0093] Test method: Take 6 pieces of metallized ceramics as samples and measure them according to the requirements of GB / T2423.22-2012. The test temperature is 110℃ / -10℃, and the cycle is 500 times. The high and low temperature are kept for 1h each cycle, and the switching time is 10s.

[0094] Judgment result: more than 300 times, the coating does not fall off, which means the performance is excellent;

[0095]

[0096]

[0097] Among them, the nickel layer is the base layer, the copper layer is the transition layer, and the gold layer is the conductive layer. The specific preparation reasons are as follows:

[0098] The main function of the primer is to enhance the adhesion between the electrode material and the substrate, ensuring that the electrode can be firmly attached to the substrate and is not easy to fall off or peel off. The primer can also pre-treat the substrate surface, fill in small defects, improve surface flatness, and provide a better foundation for the subsequent deposition of electrode materials;

[0099] The transition layer can relieve the stress caused by the difference in material properties between the conductive layer and the base layer, and prevent the electrode structure from being damaged due to excessive stress. The transition layer material usually has good conductivity and can improve the conductivity of the overall electrode to a certain extent. At the same time, the transition layer can also serve as a bridge between the conductive layer and the base layer to promote the transmission of electrons between the two. In some cases, the transition layer can also prevent the metal elements in the conductive layer from diffusing into the base layer or substrate, thereby maintaining the stability and performance of the electrode;

[0100] The conductive layer is the core part of the electrode and is responsible for transmitting current in the circuit. Therefore, the conductive layer material needs to have good conductivity and stability to ensure that the electrode can work normally. By selecting suitable conductive layer materials, such as gold, the performance of the electrode can be further optimized, the sensitivity can be improved, and the noise can be reduced. The conductive layer can also protect the electrode structure from erosion and damage from the external environment to a certain extent, thereby extending the service life of the electrode.

[0101] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing a ceramic capacitive pressure sensor electrode film, characterized in that: The following steps are involved: S1. Select a ceramic substrate, including but not limited to alumina, aluminum nitride and silicon nitride; S2. polishing the ceramic substrate; S3. Cleaning, the ceramic substrate is placed in an alcohol container, completely immersed in the solution, ultrasonically vibrated for 5 to 20 minutes at a temperature of 30 to 50 degrees Celsius, and then fully rinsed with deionized water; S4 activation, configuration activation solution, mass ratio of tin chloride: silver nitrate: hydrochloric acid: sodium acetate = 4:3:0.2:0.2, the ceramic substrate after step S3 was activated, the concentration used was 10g / L to 100g / L, soaked for 5 to 10 minutes, and then washed with deionized water; S5. Preparation of nickel layer, preparation of plating solution, sequentially adding main salt, complexing agent, reducing agent, stabilizer, deionized water, pH adjusting agent, the main salt is nickel sulfate, nickel acetate, nickel nitrate concentration is 10g / L to 50g / L; complexing agent is sodium citrate, glycine, ammonia water, one or two, concentration is 5g / L to 20g / L, reducing agent is sodium hypophosphite, sodium borohydride, hydrazine, concentration is 10g / L to 20g / L, stabilizer is ammonium chloride, thiourea, sodium thiosulfate, one or more, concentration is 5mg / L to 20mg / L, deionized water, pH adjusting agent, the plating solution pH is adjusted to 10 to 13; S6. The ceramic substrate treated in step S4 is placed in the plating solution prepared in step S5, heated in a water bath, the temperature is controlled at 50 to 70 degrees Celsius, the plating solution is slowly stirred during the reaction, the reaction time should be controlled at 5 to 8 minutes, the ceramic substrate is removed and cleaned and then vacuum dried at 80 degrees Celsius; S7 copper layer preparation, the ceramic substrate treated in step S6 is placed in the activation solution prepared in step S4 at a concentration of 10g / L to 100g / L, soaked for 5 to 10 minutes, and then washed with deionized water; S8. Prepare a plating solution, add a main salt, a complexing agent, a reducing agent, a stabilizer, deionized water and a pH adjuster in sequence, wherein the main salt is copper sulfate, copper chloride or copper nitrate, and the concentration is 10g / L to 30g / L; the complexing agent is one or two of potassium sodium tartrate, tartaric acid, and EDTA-2Na, and the concentration is 10g / L to 60g / L, the reducing agent is formaldehyde, glyoxylic acid, and the concentration is 1mL / L to 10mL / L, the stabilizer is sodium sulfite, sodium acetate, alkylbenzene sulfonate, one or more, and the concentration is 5mg / L to 10mg / L, deionized water, some, pH adjuster, the pH of the plating solution is adjusted to 10 to 12; S9. The ceramic substrate treated in step S7 is placed in the prepared plating solution in step S8, heated in a water bath, the temperature is controlled at 45 to 75 degrees Celsius, the plating solution is slowly stirred during the reaction, the reaction time should be controlled at 3 to 6 minutes, the ceramic substrate is removed and cleaned and then dried in vacuum at 80 degrees Celsius; S10 gold layer preparation, the ceramic substrate after step S9 is placed in the activation solution prepared in step S4, the concentration used is 10g / L to 100g / L, soak for 5 to 10 minutes, and then rinse with deionized water; S11. Prepare a plating solution, add a main salt, a complexing agent, a reducing agent, a stabilizer, deionized water and a pH adjuster in sequence, wherein the main salt is gold cyanide, potassium gold cyanide or potassium gold chloride trihydrate, and the concentration is 5g / L to 40g / L; the complexing agent is one or both of sodium cyanide or potassium cyanide, and the concentration is 10g / L to 40g / L; the reducing agent is glucose, sucrose or sodium hypophosphite, and the concentration is 5g / L to 10g / L; the stabilizer is one or more of ethanolamine and EDTA-2Na, and the concentration is 2mg / L to 8mg / L; some deionized water, pH adjuster, adjust the pH of the plating solution to 10 to 11; S12. Place the ceramic substrate treated in step S10 in the plating solution prepared in step S11, heat it in a water bath, control the temperature at 60 to 75 degrees Celsius, slowly stir the plating solution during the reaction, and the reaction time should be controlled at 5 to 10 minutes. Take out the ceramic substrate, clean it, and then dry it at 80 degrees Celsius in a vacuum, thus completing the preparation of the ceramic capacitive pressure sensor electrode film.

Images