A brush plating solution for processing a gold-finger gold plating layer of a PCB and a preparation process thereof
By employing a process of first plating nickel and then gold, and using modified porous SiC-nano nickel and encapsulated porous SiC-nano silver particles, a dense double-layer coating is formed. This solves the problems of insufficient coating performance and gold brittleness in gold finger repair, improves the wear resistance, corrosion resistance, and thermal conductivity of the gold finger, and reduces repair costs and time.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BRAIN POWER (QING YUAN) CO LTD
- Filing Date
- 2026-03-12
- Publication Date
- 2026-05-29
AI Technical Summary
Existing gold finger repair solutions struggle to balance repair effectiveness, cost, and practicality, resulting in insufficient coating performance, unstable particle dispersion, and the risk of gold brittleness, which in turn leads to reduced conductivity and service life.
The process of first plating nickel and then plating gold is adopted. Modified porous SiC-nano nickel particles and encapsulated porous SiC-nano silver particles are used to enhance the coating. Through the formulation of the nickel plating solution and the gold plating solution, a dense double-layer coating structure is formed, which prevents the diffusion of copper and gold and improves wear resistance, corrosion resistance and thermal conductivity.
This achieves a synergistic improvement in the wear resistance, corrosion resistance, and thermal conductivity of the coating, reducing repair costs and time, and ensuring that the gold fingers perform almost like new.
Smart Images
Figure CN122105547A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of brush plating solution preparation technology, specifically to a brush plating solution for processing gold plating layers on PCB gold fingers and its preparation process. Background Technology
[0002] PCB gold fingers, also known as edge connectors, are a series of comb-shaped conductive metal contacts located on the edge of a PCB board. They act as a "bridge" between a pluggable circuit board (such as a graphics card or memory) and the motherboard or other device sockets. Through a special gold-plated layer on the surface, they provide a stable, reliable, and low-resistance electrical connection. At the same time, they must withstand the wear caused by repeated plugging and unplugging, corrosion caused by environmental humidity, and the high temperature generated by long-term power supply. They are a core and critical structure for the normal operation of electronic devices.
[0003] In the production and use of PCB gold fingers, there are two typical repair needs: First, in the production stage: PCB gold fingers have a certain defect rate during manufacturing. These gold fingers may only have slight surface scratches, poor gold color, or color differences. After repair, they can still meet normal quality requirements. Second, in the use stage: After repeated insertion and removal, PCB gold fingers may have slight scratches and nickel leakage, slight deformation, or copper leakage points on the surface after dent repair. These gold fingers have a significant decrease in conductivity and service life due to local plating damage or loss, and need to be repaired to restore performance.
[0004] However, existing gold finger repair solutions have many technical drawbacks, making it difficult to balance repair effectiveness, cost, and practicality: some repair solutions simplify the process by only applying gold plating to the defective area without applying nickel plating. If nickel plating is not performed, the copper and gold on the gold finger will diffuse into each other under high temperature or long-term use due to the thin or missing nickel layer, forming brittle intermetallic compounds, which severely weakens the mechanical strength of the gold finger and leads to the "gold brittleness" phenomenon.
[0005] Secondly, if nickel-plating and gold-plating are not performed, the scrap rate of PCB gold fingers will increase significantly. If the defective parts of the gold fingers are put into the production line for secondary nickel-gold plating, the entire pre-treatment, electroplating, and post-treatment process must be repeated, which is not only cumbersome and has a long production cycle, but also brings high costs.
[0006] Furthermore, the current mainstream nickel plating solutions are systems composed of nickel sulfate, nickel chloride, and boric acid, while gold plating solutions are simple systems composed of potassium gold cyanide and cobalt salts. Although they can meet basic deposition requirements, they have shortcomings in key properties such as wear resistance, corrosion resistance, and thermal conductivity. In order to optimize the performance of the coating, such as wear resistance, corrosion resistance, and heat resistance, some studies have also added one or more non-water-soluble solid particles (such as silicon carbide, nano-alumina, and graphene) to the plating solution to prepare composite coatings. However, since the particles are prone to agglomeration in the plating solution, it is difficult to achieve uniform and stable suspension, resulting in uneven particle distribution in the co-deposited coating, which may bring new problems such as rough coating.
[0007] Therefore, there is an urgent need to develop a plating solution and its preparation process suitable for local repair of gold fingers. By rationally designing the formulation of nickel plating solution and gold plating solution, the problems of "gold brittleness" risk, insufficient coating performance and unstable dispersion of composite particles in the existing solution can be solved. While simplifying the repair process and controlling costs, the plating layer's wear resistance, corrosion resistance, thermal conductivity and electrical conductivity can be synergistically improved, ensuring that the repaired gold finger reaches or even approaches the performance of a brand new gold finger. Summary of the Invention
[0008] To address the aforementioned problems, this invention provides a brush plating solution for processing gold plating layers on PCB gold fingers, comprising a nickel plating solution and a gold plating solution. When repairing PCB gold fingers, nickel plating is first performed using the nickel plating solution, followed by gold plating using the gold plating solution. The nickel plating solution comprises the following raw materials: nickel sulfate, acetic acid, and deionized water. The volume ratio of deionized water to acetic acid is 1:(0.03-0.05), and the mass-volume ratio of nickel sulfate to deionized water is (430-450):1L.
[0009] The nickel plating solution also includes modified porous SiC-nano nickel particles, with a mass-to-volume ratio of (0.5-1.5) g: 1 L for the modified porous SiC-nano nickel particles and the nickel plating solution.
[0010] The preparation process of the modified porous SiC-nickel nanoparticles is as follows: Porous SiC loaded with nickel ions: Porous SiC is ultrasonically dispersed in 10 times its weight of deionized water to form a suspension. Then, nickel sulfate is added to the suspension and stirred evenly. The pH of the mixture is adjusted to 6-8 and stirred at 200 rpm for 1-2 hours at room temperature. After filtration and washing, a porous SiC-loaded nickel ion wet filter cake is obtained.
[0011] Nickel ion reduction: The porous SiC-loaded nickel ion wet filter cake was ultrasonically dispersed in 10 times its weight of deionized water at 50°C. A 0.2-0.4 mol / L sodium borohydride solution was slowly added dropwise under stirring. The reaction was carried out for 30-60 min. After filtration and washing, the porous SiC-nano nickel wet filter cake was obtained.
[0012] Modification treatment: The porous SiC-nano nickel wet filter cake is surface modified with a silane coupling agent, then filtered, washed and dried to obtain modified porous SiC-nano nickel particles.
[0013] The gold plating solution includes the following raw materials: potassium gold cyanide, potassium citrate, and deionized water, with a mass-to-volume ratio of 50g:125g:1L.
[0014] Preferably, the gold plating solution further includes potassium antimony tartrate and EDTA-2K, with 1g of potassium antimony tartrate and 3g of EDTA-2K added per 1L of deionized water, and the amount of potassium gold cyanide added is adjusted to 90.91g / L, while the amount of potassium citrate added remains unchanged.
[0015] Preferably, the mass ratio of nickel sulfate, porous SiC, and sodium borohydride is 1:(2-4):(0.3-0.32).
[0016] Preferably, the specific process of modifying the SiC-nano nickel wet filter cake is as follows: silane coupling agent and anhydrous ethanol are prepared at a mass ratio of 1:(50-100) to obtain a 1-2wt% silane coupling agent-ethanol solution. The pH of the silane coupling agent-ethanol solution is adjusted to 4-5 with hydrochloric acid. The porous SiC-nano nickel wet filter cake is added to the silane coupling agent-ethanol solution, ultrasonically dispersed for 10 min, impregnated at room temperature for 20 min, filtered, washed with anhydrous ethanol to remove unreacted silane coupling agent, and dried to obtain modified porous SiC-nano nickel particles. KH550 is preferred as the silane coupling agent.
[0017] Preferably, the mass ratio of the silane coupling agent to porous SiC is (0.1-0.3):1.
[0018] Preferably, the gold plating solution further includes encapsulated porous SiC-silver nanoparticles, with a mass-to-volume ratio of encapsulated porous SiC-silver nanoparticles to the gold plating solution of (0.3-0.5) g:1 L. The preparation process of the encapsulated porous SiC-silver nanoparticles is as follows: Porous SiC loaded with silver ions: Porous SiC is ultrasonically dispersed in 10 times its weight of deionized water, and the pH is adjusted to 7-8 with ammonia. After stirring, filtering, and washing, a porous SiC wet filter cake is obtained. An equal amount of deionized water is added again to form a suspension. Then, silver nitrate is added to the suspension, and after stirring evenly, the pH of the mixture is adjusted to 6-7. The mixture is stirred at 200 rpm for 1-2 hours at room temperature. After filtration and washing, a porous SiC wet filter cake loaded with silver ions is obtained.
[0019] Silver ion reduction: The porous SiC-supported silver ion wet filter cake was ultrasonically dispersed in 10 times its weight of deionized water at 50°C. A 0.1-0.2 mol / L sodium borohydride solution was slowly added dropwise under stirring. The reaction was carried out for 30-60 min. After filtration and washing, the porous SiC-nano silver wet filter cake was obtained.
[0020] Encapsulation process: Anhydrous ethanol and deionized water were mixed evenly at a ratio of (10-15):1 to obtain an encapsulation solution. The pH of the encapsulation solution was adjusted to 9-10 with ammonia water. Porous SiC-silver nanoparticle wet filter cake was added and ultrasonically dispersed for 10 min. TEOS was slowly added dropwise. The mixture was stirred at 50℃ and 200 rpm for 1-2 h. TEOS hydrolyzed to generate a silica nanolayer that encapsulated the outer surface of the porous SiC-silver nanoparticles. After filtration and washing with anhydrous ethanol, SiO2-encapsulated porous SiC-silver nanoparticle wet filter cake was obtained.
[0021] The mass-to-volume ratio of porous SiC to the encapsulation solution was 1 g: 15 mL; the mass ratio of porous SiC to TEOS was 1:(0.2-0.4).
[0022] Modification treatment: The coated porous SiC-silver nanoparticle wet filter cake was surface modified with a silane coupling agent, then filtered, washed and dried to obtain coated porous SiC-silver nanoparticles.
[0023] Preferably, the mass ratio of silver nitrate, porous SiC, and sodium borohydride is 1:(4-5):(0.2-0.3).
[0024] Preferably, the specific process of the modification treatment is as follows: silane coupling agent and anhydrous ethanol are prepared at a mass ratio of 1:(100-200) to obtain a 0.5-1wt% silane coupling agent-ethanol solution. The pH of the silane coupling agent-ethanol solution is adjusted to 4-5 with hydrochloric acid. The coated porous SiC-silver nanoparticle wet filter cake is added to the silane coupling agent-ethanol solution, ultrasonically dispersed for 10 min, impregnated at room temperature for 20 min, filtered, washed with anhydrous ethanol to remove unreacted silane coupling agent, and dried to obtain coated porous SiC-silver nanoparticles. The preferred silane coupling agent is KH550, and the mass ratio of the silane coupling agent to porous SiC is (0.1-0.3):1.
[0025] Preferably, the conditions for ultrasonic dispersion are ultrasonic power of 100W, ultrasonic frequency of 40kHz, and ultrasonic time of 5-10min.
[0026] The present invention also provides a process for preparing nickel plating solution and gold plating solution for PCB gold finger gold plating layer processing. The preparation process of nickel plating solution is as follows: weigh 430-450g of nickel sulfate, add deionized water and stir until the nickel sulfate is completely dissolved, slowly pour 30-50mL of acetic acid into the nickel sulfate solution while stirring, and use deionized water to make up to 1L to obtain nickel plating solution 1.
[0027] When adding modified porous SiC-nickel nanoparticles to the nickel plating solution, first disperse the modified porous SiC-nickel nanoparticles with deionized water, then slowly pour them into nickel plating solution 1 to obtain nickel plating solution 2. The amount of modified porous SiC-nickel nanoparticles added is 0.5-1.5g.
[0028] The preparation process of the gold plating solution is as follows: Add 700mL of deionized water to a beaker, weigh 125g of potassium citrate into the beaker and stir until the potassium citrate is completely dissolved, weigh 50g of potassium gold cyanide and add it into the beaker in batches while stirring until the potassium gold cyanide is completely dissolved, and use deionized water to make up to 1L to obtain gold plating solution 1.
[0029] When adding 0.3-0.5g of encapsulated porous SiC-silver nanoparticles to gold plating solution 1, the encapsulated porous SiC-silver nanoparticles are first dispersed with deionized water to form a uniform suspension, and then slowly poured into the basic gold plating solution 1. After stirring evenly, the volume is adjusted to 1L with deionized water to obtain gold plating solution 2.
[0030] The preparation process of the gold plating solution can also be as follows: Add 700mL of deionized water to a beaker, weigh 125g of potassium citrate and 3g of EDTA-2K into the beaker and stir until the potassium citrate and EDTA-2K are completely dissolved, weigh 90.91g of potassium gold cyanide and add it to the beaker in batches while stirring until the potassium gold cyanide is completely dissolved, weigh 1g of potassium antimony tartrate and dissolve it in deionized water to obtain a potassium antimony tartrate solution, slowly add the potassium antimony tartrate solution dropwise to the potassium gold cyanide solution while stirring to mix the two solutions evenly, and use deionized water to make up to 1L to obtain gold plating solution 3. When adding encapsulated porous SiC-silver nanoparticles to gold plating solution 3, the steps are the same as the preparation process of gold plating solution 2.
[0031] The present invention has at least one of the following technical effects: 1. The present invention adopts a process of first plating nickel and then plating gold, which utilizes the nickel layer to form an effective physical barrier layer between copper and gold, fundamentally preventing the mutual diffusion of copper and gold during high temperature or long-term use with electricity, thus solving the problem of gold brittleness.
[0032] 2. Porous SiC, as a hard phase, is uniformly embedded in the nickel and gold plating layers. During insertion and extraction friction, it preferentially bears the friction load, avoiding direct wear of the nickel and gold substrates, significantly reducing the wear rate of the plating layers, and significantly improving the insertion and extraction wear resistance life of PCB gold fingers. By using modified porous SiC-nano nickel particles to fill the micropores of the nickel layer, and encapsulated porous SiC-nano silver particles to fill the micropores of the gold plating layer after being encapsulated by SiO2, the double-layer plating structure becomes denser, improving the corrosion resistance of the plating layers and further enhancing the barrier effect against copper-gold diffusion.
[0033] 3. Nano silver is a highly conductive metal. Combined with the high thermal conductivity of SiC and nano silver, it constructs an efficient heat conduction path in the coating, effectively reducing temperature rise and improving the current resistance of the gold fingers.
[0034] 4. By modifying the porous SiC-nickel nanoparticles with silane coupling agent, and first encapsulating the porous SiC-silver nanoparticles with SiO2 before modifying them with silane coupling agent, the particles are uniformly distributed during the co-deposition of the coating, and the wear resistance, corrosion resistance and thermal conductivity of each area of the coating remain uniform, thus improving the repair quality.
[0035] 5. The plating solution of the present invention is suitable for localized plating repair. After simply polishing and cleaning the defective parts of the gold finger, the repair can be completed by sequentially plating nickel solution and gold solution. No complicated equipment and procedures are required, which greatly shortens the repair cycle and reduces the repair cost. Attached Figure Description
[0036] Figure 1 This is a finished product diagram of the nickel plating solution prepared in Example 10 of the present invention.
[0037] Figure 2 This is a finished product diagram of the gold plating solution prepared in Example 16 of the present invention.
[0038] Figure 3 This is a finished product image of the gold plating solution prepared in Example 17 of the present invention.
[0039] Figure 4 These are images of dense gold fingers before brush plating of the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 17.
[0040] Figure 5 These are images of dense gold fingers after brush plating with the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 17.
[0041] Figure 6 These are images of normal gold fingers before brush plating using the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 16.
[0042] Figure 7 These are images of normal gold fingers after brush plating with the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 16. Detailed Implementation
[0043] The present invention will now be described in detail through specific embodiments. However, these illustrative embodiments are for purposes and uses only to illustrate the invention and do not constitute any limitation on the actual scope of protection of the invention, nor are they intended to limit the scope of protection of the invention to these embodiments. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the scope of protection of this application. For parameter ranges not mentioned, intermediate values are selected. Furthermore, for mass percentages or weight percentages not explicitly stated or mentioned, they generally refer to the final concentration after addition.
[0044] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.
[0045] Preparation example of modified porous SiC-nickel nanoparticles
[0046] Preparation Example 1
[0047] The specific preparation process of modified porous SiC-nickel nanoparticles:
[0048] Porous SiC loaded with nickel ions: Take 10g of porous SiC and add it to 100mL of deionized water. Use 100W power, 40kHz ultrasonic frequency and sonicate for 5min to form a suspension. Then add 2.5g of nickel sulfate to the suspension and stir evenly. Adjust the pH of the mixture to 6 and stir at 200rpm for 1h at room temperature. After filtration and washing, obtain a porous SiC loaded with nickel ions wet filter cake.
[0049] Nickel ion reduction: Take 0.75g of sodium borohydride, dissolve it in deionized water to prepare a 0.2mol / L sodium borohydride solution, ultrasonically disperse the porous SiC-supported nickel ion wet filter cake in 100mL of deionized water at 50℃, slowly add sodium borohydride solution dropwise under stirring, react for 30min, filter and wash to obtain porous SiC-nano nickel wet filter cake;
[0050] Modification treatment: Prepare a 1wt% silane coupling agent-ethanol solution by mixing 1g KH550 with 100g anhydrous ethanol. Adjust the pH of the KH550-ethanol solution to 4 with hydrochloric acid. Add the porous SiC-nano nickel wet filter cake to the KH550-ethanol solution, ultrasonically disperse for 10min, impregnate at room temperature for 20min, filter, wash with anhydrous ethanol to remove unreacted KH550, and dry to obtain modified porous SiC-nano nickel particles.
[0051] Preparation Example 2
[0052] The difference from Preparation Example 1 is that: in this preparation example, the ultrasonic time is 10 min, the pH of the mixed system is 8, the stirring time is 2 h, the amount of sodium borohydride used is 0.8 g, the concentration of sodium borohydride solution is 0.4 mol / L, the mass of anhydrous ethanol is 50 g, and the pH of KH550-ethanol solution is 5.
[0053] Preparation Example 3
[0054] The difference from Preparation Example 1 is that: in this preparation example, the amount of nickel sulfate added is 5g, the amount of sodium borohydride used is 1.5g, the reaction time is 60min, the mass of anhydrous ethanol is 300g, and the mass of KH550 is 3g.
[0055] Preparation Example 4
[0056] The difference from Preparation Example 1 is as follows: In this preparation example, the ultrasonic time is 10 min, the amount of nickel sulfate added is 5 g, the pH of the mixed system is 8, the stirring time is 2 h, the amount of sodium borohydride used is 1.6 g, the concentration of sodium borohydride solution is 0.4 mol / L, the reaction time is 60 min, the mass of anhydrous ethanol is 150 g, the mass of KH550 is 3 g, and the pH of KH550-ethanol solution is 5.
[0057] Preparation example of encapsulated porous SiC-silver nanoparticles
[0058] Preparation Example 5
[0059] Porous SiC loaded with silver ions: Take 10g of porous SiC and add it to 100mL of deionized water. Use 100W power and 40kHz ultrasonic frequency for 10min. Then adjust the pH to 7 with ammonia water. Stir, filter, and wash to obtain a porous SiC wet filter cake. Add an equal amount of deionized water to form a suspension. Then add 2g of silver nitrate to the suspension and stir evenly. Adjust the pH of the mixture to 6 and stir at 200rpm for 1-2h at room temperature. After filtration and washing, obtain a porous SiC loaded with silver ions wet filter cake.
[0060] Silver ion reduction: Take 0.4g of sodium borohydride and dissolve it in deionized water to prepare a 0.1mol / L sodium borohydride solution. Disperse the porous SiC-supported silver ion wet filter cake in 100mL of deionized water with ultrasonic power of 100W, ultrasonic frequency of 40kHz, and temperature of 50℃. Add the sodium borohydride solution slowly with stirring and react for 30min. After filtration and washing, a porous SiC-nano silver wet filter cake is obtained.
[0061] Encapsulation process: Mix 150 mL of anhydrous ethanol and 10 mL of deionized water to obtain an encapsulation solution. Adjust the pH of the encapsulation solution to 9 with ammonia. Add porous SiC-silver nanoparticle wet filter cake to 150 mL of the encapsulation solution. Disperse the mixture by ultrasonication at 100 W power, 40 kHz frequency for 10 min. Slowly add 2 g of TEOS. Stir at 50 °C and 200 rpm for 1 h. TEOS hydrolyzes to generate a silica nanolayer that encapsulates the outer surface of the porous SiC-silver nanoparticles. After filtration and washing with anhydrous ethanol, obtain SiO2-encapsulated porous SiC-silver nanoparticle wet filter cake.
[0062] Modification treatment: 1g KH550 and 100g anhydrous ethanol were prepared into a 1wt% silane coupling agent-ethanol solution. The pH of the KH550-ethanol solution was adjusted to 4 with hydrochloric acid. The encapsulated porous SiC-silver nanoparticle wet filter cake was added to the KH550-ethanol solution. The mixture was ultrasonically dispersed at 100W power and 40kHz frequency for 10min. It was then immersed at room temperature for 20min, filtered, washed with anhydrous ethanol to remove unreacted KH550, and dried to obtain encapsulated porous SiC-silver nanoparticles.
[0063] Preparation Example 6
[0064] Porous SiC loaded with silver ions: Take 10g of porous SiC and add it to 100mL of deionized water. Use 100W power and 40kHz ultrasonic frequency for 10min. Then adjust the pH to 8 with ammonia water. Stir, filter, and wash to obtain a porous SiC wet filter cake. Add an equal amount of deionized water to form a suspension. Then add 2g of silver nitrate to the suspension and stir evenly. Adjust the pH of the mixture to 7 and stir at 200rpm for 1-2h at room temperature. After filtration and washing, obtain a porous SiC loaded with silver ions wet filter cake.
[0065] Silver ion reduction: Dissolve 0.6 g of sodium borohydride in deionized water to prepare a 0.2 mol / L sodium borohydride solution. Disperse the porous SiC-supported silver ion wet filter cake in 100 mL of deionized water using ultrasonication at a power of 100 W, a frequency of 40 kHz, and a temperature of 50 °C. Add the sodium borohydride solution slowly with stirring and react for 30 min. After filtration and washing, a porous SiC-nano silver wet filter cake is obtained.
[0066] Encapsulation process: Mix 150 mL of anhydrous ethanol and 15 mL of deionized water to obtain an encapsulation solution. Adjust the pH of the encapsulation solution to 10 with ammonia. Add porous SiC-silver nanoparticle wet filter cake to 150 mL of the encapsulation solution and sonicate for 10 min at a power of 100 W and a frequency of 40 kHz. Slowly add 2 g of TEOS at 50 °C and stir at 200 rpm for 1 h. TEOS hydrolyzes to generate a silica nanolayer that encapsulates the outer surface of the porous SiC-silver nanoparticles. After filtration and washing with anhydrous ethanol, obtain SiO2-encapsulated porous SiC-silver nanoparticle wet filter cake.
[0067] Modification treatment: 1g KH550 and 200g anhydrous ethanol were prepared into a 0.5wt% silane coupling agent-ethanol solution. The pH of the KH550-ethanol solution was adjusted to 5 with hydrochloric acid. The encapsulated porous SiC-silver nanoparticle wet filter cake was added to the KH550-ethanol solution and ultrasonically dispersed for 10min at an ultrasonic power of 100W and an ultrasonic frequency of 40kHz. The mixture was then immersed at room temperature for 20min, filtered, washed with anhydrous ethanol to remove unreacted KH550, and dried to obtain encapsulated porous SiC-silver nanoparticles.
[0068] Preparation Example 7
[0069] Porous SiC loaded with silver ions: Take 10g of porous SiC and add it to 100mL of deionized water. Use 100W power and 40kHz ultrasonic frequency for 10min. Then adjust the pH to 7 with ammonia water. Stir, filter, and wash to obtain a porous SiC wet filter cake. Add an equal amount of deionized water to form a suspension. Then add 2.5g of silver nitrate to the suspension and stir evenly. Adjust the pH of the mixture to 6 and stir at 200rpm for 1-2h at room temperature. After filtration and washing, obtain a porous SiC loaded with silver ions wet filter cake.
[0070] Silver ion reduction: Dissolve 0.5g of sodium borohydride in deionized water to prepare a 0.1mol / L sodium borohydride solution. Sonicate the porous SiC-supported silver ion wet filter cake in 100mL of deionized water at a power of 100W, a frequency of 40kHz, for 10min, and a temperature of 50℃. Add the sodium borohydride solution slowly with stirring and react for 30min. After filtration and washing, a porous SiC-nano silver wet filter cake is obtained.
[0071] Encapsulation process: Mix 150 mL of anhydrous ethanol and 10 mL of deionized water to obtain an encapsulation solution. Adjust the pH of the encapsulation solution to 10 with ammonia. Add porous SiC-silver nanoparticle wet filter cake to 150 mL of the encapsulation solution. Disperse the mixture by ultrasonication at 100 W and 40 kHz for 10 min. Slowly add 4 g of TEOS. Stir at 200 rpm for 2 h at 50 °C. TEOS hydrolyzes to generate a silica nanolayer that coats the outer surface of the porous SiC-silver nanoparticles. After filtration and washing with anhydrous ethanol, obtain SiO2-encapsulated porous SiC-silver nanoparticle wet filter cake.
[0072] Modification treatment: 3g KH550 and 300g anhydrous ethanol were prepared into a 1wt% silane coupling agent-ethanol solution. The pH of the KH550-ethanol solution was adjusted to 4 with hydrochloric acid. The encapsulated porous SiC-silver nanoparticle wet filter cake was added to the KH550-ethanol solution and ultrasonically dispersed for 10min at 100W power and 40kHz frequency. It was then immersed at room temperature for 20min, filtered, washed with anhydrous ethanol to remove unreacted KH550, and dried to obtain encapsulated porous SiC-silver nanoparticles.
[0073] Preparation Example 8
[0074] Porous SiC loaded with silver ions: Take 10g of porous SiC and add it to 100mL of deionized water. Sonicate for 10min at 100W power and 40kHz frequency. Adjust the pH to 8 with ammonia water, stir, filter, and wash to obtain a porous SiC wet filter cake. Add an equal amount of deionized water to form a suspension. Then add 2.5g of silver nitrate to the suspension, stir evenly, adjust the pH of the mixture to 7, and stir at 200rpm for 1-2h at room temperature. After filtration and washing, obtain a porous SiC loaded with silver ions wet filter cake.
[0075] Silver ion reduction: Dissolve 0.75g of sodium borohydride in deionized water to prepare a 0.2mol / L sodium borohydride solution. Sonicate the porous SiC-supported silver ion wet filter cake in 100mL of deionized water at 100W power, 40kHz frequency, for 10min. Add the sodium borohydride solution slowly with stirring at 50℃. React for 30min. After filtration and washing, obtain the porous SiC-nano silver wet filter cake.
[0076] Encapsulation process: Mix 150 mL of anhydrous ethanol and 15 mL of deionized water to obtain an encapsulation solution. Adjust the pH of the encapsulation solution to 10 with ammonia. Add porous SiC-silver nanoparticle wet filter cake to 150 mL of the encapsulation solution. Disperse the mixture by ultrasonication at 100 W and 40 kHz for 10 min. Slowly add 4 g of TEOS. Stir at 50 °C and 200 rpm for 1 h. TEOS hydrolyzes to generate a silica nanolayer that coats the outer surface of the porous SiC-silver nanoparticles. After filtration and washing with anhydrous ethanol, obtain SiO2-encapsulated porous SiC-silver nanoparticle wet filter cake.
[0077] Modification treatment: 3g KH550 and 600g anhydrous ethanol were prepared into a 0.5wt% silane coupling agent-ethanol solution. The pH of the KH550-ethanol solution was adjusted to 5 with hydrochloric acid. The encapsulated porous SiC-silver nanoparticle wet filter cake was added to the KH550-ethanol solution and ultrasonically dispersed for 10min at 100W power and 40kHz frequency. It was then immersed at room temperature for 20min, filtered, washed with anhydrous ethanol to remove unreacted KH550, and dried to obtain encapsulated porous SiC-silver nanoparticles.
[0078] Example of nickel plating solution preparation
[0079] Preparation Example 9
[0080] The nickel plating solution consists of 430g nickel sulfate, 30mL acetic acid, and 1L deionized water; the preparation process of the nickel plating solution is as follows:
[0081] Weigh 430g of nickel sulfate (NiSO4˙6H2O) and place it in a beaker. Add 700mL of deionized water to the beaker and stir until the nickel sulfate is completely dissolved to obtain a clear blue-green solution. Measure 30mL of acetic acid and slowly pour it into the nickel sulfate solution while stirring. Make up the volume to 1L with deionized water to obtain the nickel plating solution.
[0082] Preparation Example 10
[0083] The nickel plating solution consists of 447.78g of nickel sulfate, 40mL of acetic acid, and 1L of deionized water; the preparation process of the nickel plating solution is as follows:
[0084] Weigh 447.78g of nickel sulfate (NiSO4˙6H2O) and place it in a beaker. Add 700mL of deionized water to the beaker and stir until the nickel sulfate is completely dissolved, yielding a clear blue-green solution. Measure 40mL of acetic acid and slowly pour it into the nickel sulfate solution while stirring constantly. Make up the volume to 1L with deionized water to obtain the nickel plating solution. Figure 1 As shown.
[0085] Acetic acid is used as a buffer and complexing agent to replace the traditional boric acid system. Acetic acid has a strong buffering capacity in the pH range of 3-5, and nickel chloride is not used, thus eliminating the corrosion of gold fingers by chloride ions.
[0086] Preparation Example 11
[0087] The nickel plating solution consists of 450g nickel sulfate, 50mL acetic acid, and 1L deionized water; the preparation process of the nickel plating solution is as follows:
[0088] Weigh 450g of nickel sulfate (NiSO4˙6H2O) and place it in a beaker. Add 700mL of deionized water to the beaker and stir until the nickel sulfate is completely dissolved to obtain a clear blue-green solution. Measure 50mL of acetic acid and slowly pour it into the nickel sulfate solution while stirring. Make up the volume to 1L with deionized water to obtain the nickel plating solution.
[0089] Preparation Example 12
[0090] The difference from Preparation Example 10 is that 1.5g of the modified porous SiC-nickel nanoparticles from Preparation Example 1 were added to this preparation example. The modified porous SiC-nickel nanoparticles were first dispersed in deionized water to form a uniform suspension, and then slowly poured into the basic nickel plating solution. After stirring evenly, the solution was brought to a final volume of 1L with deionized water.
[0091] Preparation Example 13
[0092] The difference from Preparation Example 10 is that 0.5g of the modified porous SiC-nickel nanoparticles from Preparation Example 2 were added to this preparation example. The modified porous SiC-nickel nanoparticles were first dispersed in deionized water to form a uniform suspension, and then slowly poured into the basic nickel plating solution. After stirring evenly, the solution was brought to a final volume of 1L with deionized water.
[0093] Preparation Example 14
[0094] The difference from Preparation Example 10 is that 1.5g of the modified porous SiC-nickel nanoparticles from Preparation Example 3 were added to this preparation example. The modified porous SiC-nickel nanoparticles were first dispersed in deionized water to form a uniform suspension, and then slowly poured into the basic nickel plating solution. After stirring evenly, the solution was brought to a final volume of 1L with deionized water.
[0095] Preparation Example 15
[0096] The difference from Preparation Example 10 is that 0.5g of the modified porous SiC-nickel nanoparticles from Preparation Example 4 were added to this preparation example. The modified porous SiC-nickel nanoparticles were first dispersed in deionized water to form a uniform suspension, and then slowly poured into the basic nickel plating solution. After stirring evenly, the solution was brought to a final volume of 1L with deionized water.
[0097] Example of gold plating solution preparation
[0098] Preparation Example 16
[0099] The gold plating solution consists of 50g potassium gold cyanide, 125g potassium citrate, and 1L deionized water. The mass fraction of gold in the potassium gold cyanide is 68.3%. The preparation process of the gold plating solution is as follows:
[0100] Add 700mL of deionized water to a beaker. Weigh 125g of potassium citrate and add it to the beaker, stirring until the potassium citrate is completely dissolved. Weigh 50g of potassium auroxide and add it to the beaker in batches, stirring constantly, until the potassium auroxide is completely dissolved. Dilute to 1L with deionized water to obtain the gold plating solution, as shown in the attached diagram. Figure 2 As shown.
[0101] Preparation Example 17
[0102] The gold plating solution comprises 90.91g potassium gold cyanide, 125g potassium citrate, 1g potassium antimony tartrate, 3g EDTA-2K, and 1L deionized water. The mass fraction of gold in the potassium gold cyanide is 68.3%. The preparation process of the gold plating solution is as follows:
[0103] Add 700 mL of deionized water to a beaker. Weigh out 125 g of potassium citrate and 3 g of EDTA-2K, add them to the beaker, and stir until the potassium citrate and EDTA-2K are completely dissolved. Weigh out 90.91 g of potassium gold cyanide and add it to the beaker in batches, stirring constantly until the potassium gold cyanide is completely dissolved. Weigh out 1 g of potassium antimony tartrate and dissolve it in deionized water to obtain a potassium antimony tartrate solution. Slowly add the potassium antimony tartrate solution dropwise to the potassium gold cyanide solution, stirring constantly, until the two solutions are thoroughly mixed. Make up the volume to 1 L with deionized water to obtain the gold plating solution, as shown in the attached diagram. Figure 3 As shown.
[0104] Potassium citrate is used as the main complexing salt to replace the traditional potassium cyanide system, reducing toxicity. Potassium antimony tartrate is used as a grain refiner to improve the hardness and wear resistance of the coating.
[0105] Preparation Example 18
[0106] The difference from Preparation Example 16 is that 0.3g of the encapsulated porous SiC-silver nanoparticles from Preparation Example 7 were added to this preparation example. The encapsulated porous SiC-silver nanoparticles were first dispersed in deionized water to form a uniform suspension, and then slowly poured into the base gold plating solution. After stirring evenly, the solution was brought to a final volume of 1L using deionized water.
[0107] Preparation Example 19
[0108] The difference from Preparation Example 16 is that this preparation example also adds 0.3g of the encapsulated porous SiC-silver nanoparticles from Preparation Example 8. The encapsulated porous SiC-silver nanoparticles are first dispersed in deionized water to form a uniform suspension, and then slowly poured into the base gold plating solution. After stirring evenly, the volume is adjusted to 1L using deionized water.
[0109] Preparation Example 20
[0110] The difference from Preparation Example 16 is that this preparation example also adds 0.5g of the encapsulated porous SiC-silver nanoparticles from Preparation Example 5. The encapsulated porous SiC-silver nanoparticles are first dispersed in deionized water to form a uniform suspension, and then slowly poured into the basic gold plating solution. After stirring evenly, the volume is adjusted to 1L using deionized water.
[0111] Preparation Example 21
[0112] The difference from Preparation Example 16 is that this preparation example also adds 0.5g of the encapsulated porous SiC-silver nanoparticles from Preparation Example 6. The encapsulated porous SiC-silver nanoparticles are first dispersed in deionized water to form a uniform suspension, and then slowly poured into the base gold plating solution. After stirring evenly, the volume is adjusted to 1L using deionized water.
[0113] When repairing PCB gold fingers, the surface of the PCB gold fingers is first polished and cleaned. Then, nickel plating solution is used for brush plating. Within 60 minutes after brushing, gold plating solution is used for brush plating. This method is suitable for PCBs with slight scratches, slight scratches and nickel leakage, poor gold color / color difference, and gold fingers that have been repaired by dents. The nickel plating solution of Preparation Examples 9-15 and the gold plating solution of Preparation Examples 16-21 are combined to form examples and comparative examples, as shown in Table 1.
[0114] Table 1. Combination of Nickel Plating Solution and Gold Plating Solution
[0115]
[0116] When repairing PCB gold fingers using the above embodiments and comparative examples, the nickel plating layer thickness is required to be no less than 200 microinches (µ") and the gold plating layer thickness is required to be no less than 30 microinches (µ) respectively. Since manual hand-held brush plating cannot guarantee that the plating layer thickness is completely consistent, as long as the above conditions are met, the PCB gold fingers are qualified and can be used for subsequent testing. The specific thickness values are shown in Table 2.
[0117] It should be noted that, Figure 4 These are images of the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 17 before brush plating of dense gold fingers. Figure 5 These are images of dense gold fingers after brush plating with the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 17. Figure 6 These are images of normal gold fingers before brush plating using the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 16. Figure 7These are images of normal gold fingers after brush plating with the nickel plating solution prepared in Preparation Example 10 and the gold plating solution prepared in Preparation Example 16. When operators used the gold plating solutions from different preparation examples to perform brush plating repair on dense gold fingers and normal gold fingers, the gold plating solution prepared in Preparation Example 17 was more efficient in brush plating dense gold fingers, while the gold plating solution prepared in Preparation Example 16 was more efficient in brush plating normal gold fingers. Both gold plating solutions can be used for brush plating repair of PCB gold fingers, the difference being that they are more suitable for different types of PCB gold fingers.
[0118] Table 2. Brush plating thickness test results for nickel plating solutions and gold plating solutions in Examples 1-24 and Comparative Examples 1-8.
[0119]
[0120] Current withstand test:
[0121] The PCB gold fingers after brush plating repair were subjected to rated current and 1.2 times the rated current respectively. The rated current was 2A per pin. After 1 hour of power-on, the surface temperature of the PCB gold finger contact area at the beginning and end of power-on was measured with an infrared thermometer and recorded as t1 and t2 respectively. The test results are shown in Table 3.
[0122] Table 3. Temperature Changes in Current Resistance Testing of Repaired PCB Gold Fingers
[0123]
[0124] Silver is the metal with the best known electrical conductivity. Silver ions are loaded onto the porous SiC surface and reduced to silver nanoparticles by sodium borohydride. After being encapsulated by SiO2, they are uniformly dispersed in the gold plating layer. The silver nanoparticles fill the micropores generated during the gold plating deposition process. SiC has excellent thermal conductivity, and silver nanoparticles also have high thermal conductivity. The two work together to build an efficient heat conduction pathway in the plating layer, which accelerates the diffusion of heat from the contact area to the surrounding area, avoids local overheating, improves the current resistance of the repaired PCB gold fingers, and to a certain extent reduces the mutual diffusion between copper and gold, thus reducing the risk of gold brittleness.
[0125] By encapsulating porous SiC-silver nanoparticles, the encapsulation layer isolates oxygen, preventing silver from oxidizing into silver oxide and reducing its conductivity. The dense SiO2 layer effectively blocks corrosive media from contacting the silver nanoparticles. At the same time, the SiO2 encapsulation layer enhances the interfacial bonding between the silver nanoparticles and the gold layer, preventing the silver nanoparticles from detaching from the gold layer and forming gaps, thus preventing crevice corrosion.
[0126] As can be seen from Table 3, compared with Comparative Examples 1-6, after adding encapsulated porous SiC-silver nanoparticles to the gold plating solution, the surface temperature rise of the PCB gold fingers after being powered on was lower than that without the addition of encapsulated porous SiC-silver nanoparticles. It can be seen that encapsulated porous SiC-silver nanoparticles have a positive effect on the current resistance of the repaired PCB gold fingers.
[0127] Corrosion resistance and abrasion resistance testing:
[0128] The repaired area was partially covered, and the uncovered part was first tested for corrosion resistance. Then the covered area was switched, and the other part was tested for abrasion resistance. Fluororubber patches were selected as the covering material, and the boundary was reinforced with silicone sealant.
[0129] The corrosion resistance of the PCB gold fingers repaired in the above examples and comparative examples was tested using a neutral salt spray test. The specific procedure was as follows: The repaired PCB gold finger samples were placed at a 30° angle on the sample rack of the salt spray chamber, ensuring that the salt spray evenly covered the repaired area and that there was no obstruction between the PCB gold fingers. Continuous spray mode was turned on, with a temperature of 35°C, a salt solution pH of 7, and a spray volume of 2 mL / 80 cm²·h. In the first 24 hours, the machine was stopped and observed every 12 hours to check whether there were any plating peeling, bubbles, or corrosion spots on the surface of the PCB gold fingers. From 24 to 48 hours, the machine was stopped and observed every 8 hours. After 48 hours, the machine was observed every 6 hours. The time of the first plating peeling (t3) and the time of complete plating failure (t4) were recorded respectively.
[0130] The number of insertions and removals of PCB gold fingers was tested using an insertion and removal life tester. The insertion and removal speed was 20 times per minute. For the first 2000 insertions and removals, an observation was made every 500 insertions and removals; for 2000-2800 insertions and removals, an observation was made every 400 insertions and removals; and for more than 2800 insertions and removals, an observation was made every 100 insertions and removals. The number of insertions and removals was recorded when exposed nickel, exposed copper, plating peeling, cracking, or obvious scratches appeared in the repair area. The specific results are shown in Table 4.
[0131] Table 4. Test results of corrosion resistance and abrasion resistance of the repaired PCB gold fingers.
[0132]
[0133] Porous SiC itself is an ultra-hard ceramic material. As a dispersed phase, it is uniformly embedded in the nickel and gold plating layers. When the plating is subjected to insertion and extraction friction, the hard SiC phase preferentially contacts the friction medium and bears the main friction load, avoiding direct wear of the nickel substrate and significantly reducing the wear rate of the plating. Therefore, the friction resistance of the repaired PCB gold fingers is basically close to that of qualified PCB gold fingers, meeting the repair requirements.
[0134] Nickel ions are loaded onto the porous SiC surface and reduced to nano-nickel particles by sodium borohydride. The nano-nickel fills the pores of the porous SiC, forming a composite structure of SiC hard framework and nano-nickel filling. It is uniformly dispersed in the nickel plating layer, making the plating structure more compact. Furthermore, nickel ions and nano-nickel improve the corrosion resistance of the plating layer from the root by forming a dense barrier layer, isolating copper-gold diffusion, and filling corrosion channels.
[0135] As can be seen from Table 4, the more SiC is added, the stronger the corresponding friction resistance. Examples 7 and 10 are brush plating with the same nickel plating solution, but the amount of encapsulated porous SiC-nano silver particles added to the gold plating solution is different. The insertion and extraction life of Example 10 is better than that of Example 7.
[0136] Examples 13-16 involve adding appropriate amounts of inorganic nanoparticles to both nickel plating solution and gold plating solution, resulting in superior corrosion resistance and abrasion resistance compared to other examples. Depending on the application scenario and requirements of the PCB gold fingers, inorganic nanoparticles can be added only to the nickel plating solution or the gold plating solution, or inorganic nanoparticles can be added to both the nickel plating solution and the gold plating solution.
[0137] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.
[0138] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.
Claims
1. A brush plating solution for processing gold plating on PCB gold fingers, comprising a nickel plating solution and a gold plating solution, wherein in the repair of PCB gold fingers, nickel plating is first performed using the nickel plating solution, followed by gold plating using the gold plating solution, characterized in that... The nickel plating solution includes the following raw materials: nickel sulfate, acetic acid, and deionized water. The volume ratio of deionized water to acetic acid is 1:(0.03-0.05), and the mass-volume ratio of nickel sulfate to deionized water is (430-450):1L. The nickel plating solution also includes modified porous SiC-nano nickel particles, with a mass-to-volume ratio of (0.5-1.5) g: 1 L for the modified porous SiC-nano nickel particles and the nickel plating solution. The preparation process of the modified porous SiC-nickel nanoparticles is as follows: Porous SiC loaded with nickel ions: Porous SiC is dispersed in 10 times its weight of deionized water to form a suspension. Then, nickel sulfate is added to the suspension and mixed and stirred evenly. The pH of the mixture is adjusted to 6-8 and stirred for 1-2 hours. After filtration and washing, a wet filter cake of porous SiC loaded with nickel ions is obtained. Nickel ion reduction: The porous SiC-supported nickel ion wet filter cake is dispersed in 10 times its weight of deionized water. Sodium borohydride solution is slowly added dropwise under stirring. The reaction is carried out for 30-60 minutes. After filtration and washing, porous SiC-nano nickel wet filter cake is obtained. Modification treatment: After the porous SiC-nano nickel wet filter cake is surface modified with silane coupling agent, it is filtered, washed and dried to obtain modified porous SiC-nano nickel particles. The gold plating solution includes the following raw materials: potassium gold cyanide, potassium citrate, and deionized water, with a mass-to-volume ratio of 50g:125g:1L.
2. The brush plating solution for processing gold plating layer on PCB gold fingers according to claim 1, characterized in that... The gold plating solution also includes potassium antimony tartrate and EDTA-2K. 1g of potassium antimony tartrate and 3g of EDTA-2K are added to every 1L of deionized water, and the amount of potassium gold cyanide added is adjusted to 90.91g / L, while the amount of potassium citrate added remains unchanged.
3. The brush plating solution for processing gold plating layer on PCB gold fingers according to claim 1, characterized in that... The mass ratio of nickel sulfate, porous SiC, and sodium borohydride is 1:(2-4):(0.3-0.32).
4. The brush plating solution for processing gold plating layer on PCB gold fingers according to claim 1, characterized in that... The specific process of the SiC-nano nickel wet filter cake modification treatment is as follows: A silane coupling agent and anhydrous ethanol were prepared at a mass ratio of 1:(50-100) to obtain a 1-2 wt% silane coupling agent-ethanol solution. The pH of the silane coupling agent-ethanol solution was adjusted to 4-5 with hydrochloric acid. The porous SiC-nano nickel wet filter cake was added to the silane coupling agent-ethanol solution, ultrasonically dispersed for 10 min, impregnated at room temperature for 20 min, filtered, washed with anhydrous ethanol to remove unreacted silane coupling agent, and dried to obtain modified porous SiC-nano nickel particles.
5. The brush plating solution for processing gold plating layer on PCB gold fingers according to claim 4, characterized in that... In the SiC-nano nickel wet filter cake modification process, the mass ratio of the silane coupling agent to the porous SiC in the porous SiC-nano nickel wet filter cake is (0.1-0.3):
1.
6. A brush plating solution for processing gold plating layer on PCB gold fingers according to any one of claims 1 or 2, characterized in that... The gold plating solution also includes encapsulated porous SiC-silver nanoparticles, with a mass-to-volume ratio of (0.3-0.5) g:1 L for the encapsulated porous SiC-silver nanoparticles to the gold plating solution. The preparation process of the encapsulated porous SiC-silver nanoparticles is as follows: Porous SiC loaded with silver ions: Porous SiC is dispersed in 10 times its weight of deionized water, and the pH is adjusted to 7-8 with ammonia. After stirring, filtering, and washing, a porous SiC wet filter cake is obtained. An equal amount of deionized water is added again to form a suspension. Silver nitrate is then added to the suspension, and after stirring evenly, the pH of the mixture is adjusted to 6-7. The mixture is stirred for 1-2 hours, and after filtering and washing, a porous SiC wet filter cake loaded with silver ions is obtained. Silver ion reduction: The porous SiC-supported silver ion wet filter cake is dispersed in 10 times its weight of deionized water. Sodium borohydride solution is slowly added dropwise under stirring. The reaction is carried out for 30-60 minutes. After filtration and washing, porous SiC-nano silver wet filter cake is obtained. Encapsulation process: Anhydrous ethanol and deionized water were mixed evenly at a ratio of (10-15):1 to obtain an encapsulation solution. The pH of the encapsulation solution was adjusted to 9-10 with ammonia water. Porous SiC-silver nanoparticle wet filter cake was added and ultrasonically dispersed for 10 min. TEOS was slowly added dropwise at 50℃ and stirred for 1-2 h. TEOS hydrolyzed to generate a silica nanolayer that coated the outer surface of the porous SiC-silver nanoparticles. After filtration and washing with anhydrous ethanol, SiO2-encapsulated porous SiC-silver nanoparticle wet filter cake was obtained. During the encapsulation process, the mass-to-volume ratio of porous SiC to encapsulation liquid in the porous SiC-silver nanoparticle wet filter cake was 1 g:15 mL; the mass ratio of porous SiC to TEOS in the porous SiC-silver nanoparticle wet filter cake was 1:(0.2-0.4). Modification treatment: The coated porous SiC-silver nanoparticle wet filter cake was surface modified with a silane coupling agent, then filtered, washed and dried to obtain coated porous SiC-silver nanoparticles.
7. The brush plating solution for processing gold plating layer on PCB gold fingers according to claim 6, characterized in that... The mass ratio of silver nitrate, porous SiC, and sodium borohydride is 1:(4-5):(0.2-0.3).
8. The brush plating solution for processing gold plating layer on PCB gold fingers according to claim 7, characterized in that... The specific process of the modification treatment is as follows: A silane coupling agent and anhydrous ethanol were prepared at a mass ratio of 1:(100-200) to obtain a 0.5-1wt% silane coupling agent-ethanol solution. The pH of the silane coupling agent-ethanol solution was adjusted to 4-5 with hydrochloric acid. The coated porous SiC-silver nanoparticle wet filter cake was added to the silane coupling agent-ethanol solution, ultrasonically dispersed for 10 min, impregnated at room temperature for 20 min, filtered, washed with anhydrous ethanol to remove unreacted silane coupling agent, and dried to obtain coated porous SiC-silver nanoparticles. The mass ratio of the silane coupling agent to porous SiC was (0.1-0.3):
1.
9. The preparation process of a nickel plating solution for PCB gold finger gold plating layer processing according to claim 1, characterized in that... Includes the following steps: Weigh 430-450g of nickel sulfate, add 700mL of deionized water and stir until the nickel sulfate is completely dissolved. Slowly pour 30-50mL of acetic acid into the nickel sulfate solution while stirring. Use deionized water to bring the volume to 1L to obtain the nickel plating solution. When adding modified porous SiC-nano nickel particles to the nickel plating solution, first disperse the modified porous SiC-nano nickel particles with deionized water, and then slowly pour them into the nickel plating solution. The amount of modified porous SiC-nano nickel particles added is 0.5-1.5g.
10. The preparation process of the gold plating solution for PCB gold finger gold plating layer processing according to claim 6, characterized in that... Includes the following steps: Add 700mL of deionized water to a beaker, weigh 125g of potassium citrate and pour it into the beaker and stir until the potassium citrate is completely dissolved. Weigh 50g of potassium gold cyanide and add it to the beaker in batches while stirring until the potassium gold cyanide is completely dissolved. Use deionized water to make up to 1L to obtain the gold plating solution. When adding 0.3-0.5g of encapsulated porous SiC-silver nanoparticles to the gold plating solution, the encapsulated porous SiC-silver nanoparticles are first dispersed in deionized water to form a uniform suspension, and then slowly poured into the base gold plating solution. After stirring evenly, the solution is then diluted to 1L with deionized water.