Printed circuit board surface treatment process

Abstract

The invention relates to the field of printed circuit board manufacturing, and discloses a printed circuit board surface treatment process which comprises the following steps: S1, preparing an acid solution and preheating the acid solution to a set temperature, and accurately controlling the concentration and temperature of the acid solution in a micro-etching process; s2, pre-cleaning the circuit board, removing impurities and pollutants on the surface of the circuit board, and ensuring the uniformity in the micro-etching process; s3, soaking the cleaned circuit board in an accurately controlled acid solution, and performing micro-etching treatment under the conditions of set temperature, acid concentration and time; and S4, in the micro-etching process. According to the method, the concentration, the temperature and the reaction time of the acid liquor are accurately controlled, an oxide layer is ensured to be uniformly removed, uneven local corrosion is avoided, and the uniformity and the adhesive force of a coating are ensured through a precise quality detection method, so that the quality and the stability of surface treatment of the circuit board are improved, and multiple problems in the prior art are solved.

Description

Technical Field

[0001] The invention relates to the field of printed circuit board manufacturing, in particular to a surface treatment process for a printed circuit board. Background Art

[0002] In the electronics manufacturing industry, the surface treatment process of printed circuit boards (PCBs) is a key link in ensuring the long-term reliability of products. Existing PCB surface treatment processes mainly include micro-etching steps to remove the oxide layer on the surface of the circuit board and coating with an anti-oxidation coating to prevent subsequent oxidation. These processes remove the oxide layer through an acidic solution and protect the surface with a coating. Traditional micro-etching processes generally rely on soaking or spraying of acid solution to achieve the purpose of removing the oxide layer by controlling the concentration and reaction time of the acid solution. Although the process is simple and low-cost, it often faces problems such as low precision and unstable process in actual applications.

[0003] The micro-etching process in the prior art lacks precise control, and the concentration and reaction time of the acid solution are often adjusted by empirical means. This method not only leads to uneven removal of the oxide layer, but also local excessive corrosion or failure to completely remove the oxide layer, which affects the adhesion of the subsequent coating and the overall performance of the circuit board. At the same time, the flow and distribution of the acid solution usually rely on simple stirring or acid immersion, and fail to be optimized by fluid dynamics, resulting in uneven coverage of the acid solution on the surface of the circuit board. The inconsistency between the acid flow rate and the flow path causes the problem of uneven treatment in local areas. The temperature control system is also relatively simple in the prior art, with large temperature fluctuations, and it is impossible to stably control the reaction rate of the acid solution, which in turn affects the removal effect of the oxide layer. In addition, the existing quality inspection methods also have shortcomings. Most of them rely on manual visual inspection or electrical performance testing, and cannot fully evaluate the adhesion of the coating and the uniformity of the surface treatment, and are prone to missed inspections or misjudgments. Therefore, the prior art has obvious deficiencies in accuracy, stability and reliability, which restricts the quality control of the surface treatment process and product consistency. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a printed circuit board surface treatment process, which solves the problems of uneven acid treatment, unstable temperature control, insufficient coating adhesion and inaccurate quality detection means in the prior art.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A printed circuit board surface treatment process comprises the following steps: S1, preparing an acid solution and preheating it to a set temperature, wherein the concentration and temperature of the acid solution are precisely controlled during the micro-etching process; S2. Pre-clean the circuit board to remove impurities and contaminants on its surface to ensure uniformity during micro-etching; S3, immersing the cleaned circuit board in a precisely controlled acid solution, and performing micro-etching treatment under set temperature, acid concentration and time conditions; S4. During the micro-etching process, the acid flow rate and distribution are optimized through the fluid dynamics model to ensure that the acid evenly covers the circuit board surface; S5. Optimize the temperature field distribution through the heat conduction model to ensure the uniform temperature of the acid during the micro-etching process; S6, drying the micro-etched circuit board to remove residual acid and moisture; S7, coating an anti-oxidation coating on the surface of the circuit board, and curing the coating by heating to fix the coating; S8. Perform quality inspection on the processed circuit boards to ensure that the surface treatment is uniform and meets quality standards.

[0006] Preferably, the preheating temperature of the acid solution is between 40°C and 80°C.

[0007] Preferably, the concentration of the acid solution is between 5% and 30%, and the concentration of the acid solution is monitored and adjusted in real time during the micro-etching process to ensure the reactivity of the acid solution during the micro-etching process.

[0008] Preferably, the reaction temperature during the micro-etching process is monitored in real time by an intelligent temperature control system and maintained between 40° C. and 60° C. to ensure uniform removal of the oxide layer.

[0009] Preferably, the fluid dynamics model uses computational fluid dynamics simulation to optimize the flow rate and flow path of the acid solution to ensure that the acid solution is evenly distributed on the surface of the circuit board and the flow rate is controlled between 1 and 5 m / s.

[0010] Preferably, the anti-oxidation coating uses an antioxidant containing nanoparticles, the adhesion of the coating is improved by more than 10% compared with traditional coatings, and the curing temperature is 80° C. to 120° C. and the curing time is 5 to 15 minutes.

[0011] Preferably, the micro-etching step simulates the dissolution reaction between the acid solution and the circuit board surface and precisely adjusts the reaction time to ensure uniform removal of the oxide layer, and the reaction time is controlled between 5 seconds and 60 seconds.

[0012] Preferably, the temperature control system automatically adjusts the acid solution temperature based on real-time sensor data to ensure that the temperature does not vary by more than ±2°C within a set range, so as to avoid adverse effects of temperature fluctuations on the reaction rate.

[0013] Preferably, the quality inspection is performed by scanning the surface of the circuit board with a scanning electron microscope to analyze the uniformity of oxide layer removal and the adhesion of the anti-oxidation coating, and adjusting the process parameters according to the inspection results to ensure that each batch of products meets the quality standards.

[0014] Preferably, the acid solution comprises sulfuric acid, chloride, fluoride or other chemical solutions suitable for removing oxides from the surface of PCB, and the pH value of the acid solution is between 1 and 3.

[0015] The present invention provides a printed circuit board surface treatment process, which has the following beneficial effects: 1. The present invention achieves uniform removal of the oxide layer during micro-etching by adopting a technical solution of precisely controlling the acid concentration, temperature and reaction time. Compared with the empirical method commonly used in the prior art to adjust the acid, which easily leads to incomplete removal of the oxide layer or local excessive corrosion, the present invention effectively avoids these problems and ensures the consistency and stability of the circuit board surface treatment.

[0016] 2. The present invention uses a fluid dynamics optimization technical solution to make the acid flow more evenly on the surface of the circuit board, thereby maximizing the micro-etching effect. Compared with the uneven flow of acid in traditional technologies, which easily causes uneven local corrosion, the present invention can ensure that the acid evenly covers every area of ​​the circuit board, significantly improving the uniformity of oxide layer removal.

[0017] 3. The present invention adopts a precise temperature control system to adjust the acid solution temperature in real time during the micro-etching process, thereby achieving the technical effect of stabilizing the reaction rate. In the prior art, large temperature fluctuations often lead to uneven removal of the oxide layer or corrosion of the substrate. The present invention ensures the consistency of the reaction temperature through real-time monitoring and automatic adjustment, thereby avoiding the impact of unstable temperature.

[0018] 4. The present invention realizes high-precision detection of surface treatment quality by combining a scanning electron microscope with other detection technologies, and achieves the technical effect of quickly identifying and correcting coating defects. Compared with manual visual inspection in traditional detection methods, the present invention provides a more objective and efficient detection method, which significantly improves the consistency and qualification rate of products. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings of the present invention specification 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.

[0021] Please refer to the attached Figure 1 The present invention provides a printed circuit board surface treatment process, comprising the following steps: S1. Prepare the acid solution and preheat it to the set temperature. The concentration and temperature of the acid solution are precisely controlled during the micro-etching process. In the present embodiment, the preparation of the acid solution is first carried out based on the concentration and type of the selected acidic solution. Common acid solution components include sulfuric acid, chloride, fluoride, etc., which have strong oxidizing ability and can effectively remove the oxide layer on the surface of the circuit board. In the selection of the concentration of the acid solution, it is usually set to between 5% and 30%. Too high a concentration may cause excessive corrosion, while too low a concentration will affect the removal effect of the oxide layer. Depending on the specific circuit board material and the type of oxide layer, the acid solution concentration will be different. Therefore, in actual operation, it is necessary to determine the optimal acid solution concentration through experiments.

[0022] As an option, the acid solution may include sulfuric acid, chloride or fluoride, etc., and its concentration can be adjusted according to specific needs. Generally, sulfuric acid, as one of the components of the acid solution, is widely used in electronic manufacturing. Its concentration is usually maintained between 10% and 20%, which can effectively remove the oxide layer without excessively corroding the substrate.

[0023] Specifically, the preheating temperature of the acid is controlled between 40°C and 80°C to ensure that the acid has good reactivity. Too low a temperature will reduce the reaction rate of the acid, and the oxide layer may not be completely removed; too high a temperature may accelerate the reaction rate and cause excessive corrosion. Therefore, the accuracy of the temperature control equipment is one of the core technologies of this step. The temperature control system monitors the real-time temperature through a sensor and adjusts it to the set value through an automatic heating device to ensure the stability of the reaction temperature.

[0024] In one possible implementation, the real-time adjustment of the acid temperature uses a closed-loop control system that can accurately respond to temperature changes. The system consists of a heater, a temperature control sensor, and a central control unit. The sensor provides real-time feedback on the temperature of the acid, and the control unit automatically adjusts the heating power according to the set temperature range to ensure that the acid is within the optimal reaction temperature range. This control method helps to improve the efficiency and effect of micro-etching.

[0025] In some embodiments, the preheating temperature of the acid solution can be specifically selected between 60°C and 70°C to ensure the stability of the acid solution and prevent excessive reaction caused by excessive temperature. The optimization of temperature and concentration control can ensure the uniformity of the acid solution reaction and avoid excessive corrosion in local areas or incomplete removal of the oxide layer.

[0026] In another possible implementation, the reaction characteristics of the acid solution can be further precisely adjusted by setting a temperature curve. For example, the acid solution can be set to have a lower temperature in the initial stage and gradually increase to the set optimal reaction temperature during the micro-etching reaction. This control method is suitable for specific materials and oxide layers that are sensitive to temperature, and can ensure efficient and uniform removal of the oxide layer.

[0027] During the preheating process, the thermodynamic changes of the acid liquid can be described by the heat conduction equation. According to Fourier's heat conduction law, the acid liquid will be affected by heat transfer during the preheating process, and the change of the temperature field is controlled by the following equation: Where T is the temperature of the acid solution, t is the time, α is the thermal diffusion coefficient of the acid solution, By real-time monitoring of the temperature gradient and the thermal diffusivity of the acid, the temperature control system can accurately adjust the heating power to ensure that the temperature of the acid is evenly distributed throughout the process.

[0028] Through accurate acid preparation and temperature control, the acid can maintain optimal reactivity throughout the micro-etching process, ensuring that the oxide layer is evenly removed. This avoids uneven surface corrosion or incomplete oxide layer removal caused by temperature fluctuations or unstable concentrations. In addition, precise temperature regulation can avoid energy waste and improve process efficiency and controllability.

[0029] In summary, the acid solution preheating and preparation steps in this embodiment ensure the uniformity and stability of the micro-etching reaction by precisely controlling the acid solution concentration, temperature and its changing process, laying a solid foundation for the smooth progress of the subsequent surface treatment process.

[0030] S2. Pre-clean the circuit board to remove surface impurities and contaminants to ensure uniformity during micro-etching. In this embodiment, deionized water or a special cleaning solution is usually used for pre-cleaning of the circuit board. Specifically, deionized water can effectively remove water-soluble impurities on the surface, while the special cleaning solution can clean non-water-soluble contaminants such as grease and stains. In the process of cleaning the circuit board, different methods such as ultrasonic cleaning, mechanical brushing or immersion cleaning can be used.

[0031] Generally, to ensure thorough cleaning, deionized water is first used for preliminary rinsing to remove water-soluble impurities. Subsequently, ultrasonic cleaning equipment is used to further remove surface grease and tiny particles. Ultrasonic cleaning generates tiny bubbles through high-frequency vibration, which burst during the vibration process and can effectively remove stubborn contaminants attached to the surface of the circuit board.

[0032] As an option, if the surface contamination of the circuit board is complex, you can consider using a special degreasing cleaning fluid. The active ingredients in the cleaning fluid can dissolve grease and other organic pollutants on the surface of the circuit board. Usually, the concentration of the cleaning fluid is adjusted according to the nature of the pollutants and the cleaning requirements. Too high a concentration may cause damage to the surface of the circuit board, while too low a concentration may not be cleaned thoroughly.

[0033] Specifically, after cleaning, the circuit board needs to be thoroughly rinsed with deionized water or pure water to ensure that there is no residual cleaning agent or impurities. The purpose of this step is to prevent the cleaning solution from interfering with the subsequent micro-etching process, while ensuring that the micro-etching acid can evenly contact the surface of the circuit board.

[0034] In one possible implementation, after the circuit board is cleaned, an air blowing system can be used to initially dry the circuit board to remove residual moisture on the surface. Especially after rinsing with deionized water, residual moisture may affect the adhesion of subsequent coatings, so it is very important to ensure that the surface is completely dry.

[0035] In some embodiments, in order to prevent the cleaning solution from causing long-term corrosion to the circuit board or affecting the structure of the circuit board material, warm water can be used for secondary rinsing after cleaning. The use of warm water helps to remove residual chemicals in the cleaning solution, thereby further improving the cleaning effect.

[0036] During ultrasonic cleaning, the formation and bursting of bubbles are caused by the vibration of sound waves. When sound waves propagate through liquid, they produce sound pressure fluctuations, causing tiny bubbles to form locally in the liquid. When the sound waves reach a certain intensity, the bubbles will expand rapidly and collapse in a short period of time. The process can be described by the Rayleigh-Plesset equation: Where P(t) is the bubble radius, R0 is the initial radius of the bubble, P(t) is the instantaneous pressure around the bubble, and P ∞ is the ambient pressure of the liquid, and ρ is the density of the liquid. By adjusting the frequency and power of the ultrasonic wave, the size and collapse intensity of the bubbles can be precisely controlled, thereby improving the cleaning effect.

[0037] By using a combination of deionized water, ultrasonic cleaning and special cleaning fluid, various contaminants on the circuit board surface can be effectively removed, ensuring that the acid can evenly contact the surface, thereby improving the effect of the subsequent micro-etching process. In particular, the use of ultrasonic cleaning technology can remove tiny particles and grease without damaging the circuit board, preventing these impurities from interfering with the subsequent acid reaction and ensuring the uniform removal of the oxide layer. At the same time, there is no contaminant residue on the surface of the circuit board after thorough cleaning, which provides a good foundation for subsequent coating adhesion and anti-oxidation protection.

[0038] In summary, the circuit board surface pre-cleaning step in this embodiment effectively removes pollutants on the circuit board surface by reasonably selecting cleaning liquid, cleaning method and cleaning equipment, and enhances the cleaning effect by ultrasonic and other means, ensuring the smooth progress of subsequent micro-etching and coating steps.

[0039] S3, immersing the cleaned circuit board in a precisely controlled acid solution, and performing micro-etching treatment under set temperature, acid concentration and time conditions; In this embodiment, the concentration of the acid solution during the micro-etching process is controlled between 5% and 30%. The chemical components in the acid solution react with the surface of the circuit board, and the oxide layer is removed within a certain period of time. In order to ensure the uniformity of the oxide layer removal and prevent excessive corrosion, this step is carried out under specific temperature and reaction time conditions. The reaction temperature is generally maintained between 40°C and 60°C, and the reaction time is generally set between 5 seconds and 60 seconds. The specific value is adjusted according to the circuit board material and the thickness of the oxide layer.

[0040] Generally, in this step, the flow rate of the acid solution and the contact time of the acid solution with the circuit board are crucial. By optimizing the acid solution flow path, ensure that the acid solution can evenly cover the circuit board surface to avoid local excessive corrosion. In certain embodiments, by adopting fluid dynamics simulation (CFD) technology, optimize the speed and direction of the acid solution flow, thereby ensure that the acid solution is more evenly processed on the circuit board. The flow mode, flow rate and direction of the acid solution on the circuit board surface can be optimized by adjusting the design of the micro-etching groove and the acid solution supply system.

[0041] As an option, in order to improve the uniformity and reaction rate of the acid, a circulating flow system can be considered, in which the acid circulates through pipes to ensure that every part of the circuit board surface is exposed to fresh acid, thereby improving the reaction efficiency.

[0042] Specifically, the reaction time of the acid solution is also a key factor affecting the effect of oxide layer removal. Too long a reaction time may cause corrosion of the substrate, while too short a time may result in the oxide layer not being completely removed. Therefore, the above problems can be avoided by accurately controlling the reaction time. Usually, when the oxide layer on the surface of the circuit board is thinner, the reaction time is shorter; if the oxide layer is thicker, the reaction time is correspondingly extended. In order to ensure the accuracy of the reaction time, an automated control system is used in this embodiment for real-time monitoring, and dynamic adjustments are made based on feedback data.

[0043] In one possible implementation, the temperature control of the acid solution is performed by an intelligent temperature control system. The temperature control system monitors the temperature of the acid solution in the micro-etching tank in real time to ensure that the temperature is always kept within the set range. Unstable temperature control may lead to inconsistent reaction rates, thereby affecting the uniformity of oxide layer removal. Usually, the temperature of the acid solution is adjusted between 40°C and 60°C. When the temperature is too low, the reaction rate is slow, and when the temperature is too high, it may cause corrosion of the circuit board substrate.

[0044] In some embodiments, to ensure uniformity of the reaction rate, the acidity (pH value) of the acid solution will gradually decrease as the reaction proceeds. Generally, the micro-etching reaction will proceed at a pH value in the range of 1 to 3. Acidic solutions in this range can effectively dissolve the oxide layer without causing excessive corrosion to the circuit board material.

[0045] In one possible implementation, in order to further optimize the uniformity and efficiency of the micro-etching process, it is possible to consider using a low-frequency vibration system to slightly vibrate the circuit board so that the acid can produce a better flow effect on the surface of the circuit board, thereby improving the micro-etching effect.

[0046] In the micro-etching process, the relationship between the reaction rate and the acid concentration, temperature and reaction time can be described by the following formula: Where k is the reaction rate constant, A is the prefactor, and E a is the reaction activation energy, R is the gas constant, and T is the acid temperature. This formula shows that the temperature and reaction rate are exponentially related, and the increase in temperature will accelerate the removal of the oxide layer.

[0047] Further considering the effect of acid concentration and reaction time on the reaction rate, the reaction rate is not only affected by temperature, but also by acid concentration. When the concentration is high, the acid reaction is more intense, but it may also cause corrosion of the substrate, so the acid concentration needs to be kept within an appropriate range.

[0048] By precisely controlling parameters such as acid concentration, temperature, reaction time and flow rate, the micro-etching process can achieve uniform removal of the oxide layer and avoid excessive corrosion. Furthermore, through the combination of the fluid optimization system and the intelligent temperature control system, the acid is evenly distributed on the surface of the circuit board, thereby improving the stability and consistency of the reaction effect. Control of the reaction time ensures the thoroughness of the oxide layer removal without affecting the integrity of the substrate. In addition, through the automated control system, the reaction parameters can be monitored and adjusted in real time to avoid human operating errors and improve the accuracy and reliability of the process.

[0049] In summary, the micro-etching process in this embodiment ensures uniform removal of the oxide layer on the surface of the circuit board by optimizing key factors such as acid solution preparation, temperature control, reaction time and flow rate, and provides an ideal substrate for subsequent anti-oxidation coating. These technical optimizations ensure the efficiency and stability of the micro-etching process, providing strong support for the production of high-quality printed circuit boards.

[0050] S4. During the micro-etching process, the acid flow rate and distribution are optimized through the fluid dynamics model to ensure that the acid evenly covers the circuit board surface; In this embodiment, fluid dynamics optimization is performed by computational fluid dynamics (CFD) simulation technology. In this process, a fluid dynamics model is first established based on the shape and size of the circuit board and the flow characteristics of the acid solution to simulate the flow behavior of the acid solution in the micro-etching groove. This simulation can predict the speed and direction of the acid solution flowing on the circuit board surface and calculate the optimal flow rate, flow path and acid solution distribution pattern.

[0051] Generally, the acid flow rate is controlled between 1 and 5 m / s. A flow rate that is too low will cause the acid to stay on the circuit board surface for too long, causing uneven corrosion; while a flow rate that is too high may cause the acid to flow quickly over the circuit board surface and fail to fully contact the oxide layer. Therefore, optimizing the flow rate is one of the core of this step. The flow rate control is accurately calculated through fluid simulation to ensure that the acid can evenly cover the circuit board surface and fully react with the oxide layer within the appropriate time.

[0052] As an option, in fluid dynamics optimization, the flow path of the acid also needs to be designed to ensure that the oxide layer in each area can be treated evenly. By optimizing the structure of the micro-etching tank and the flow direction of the acid, the acid can flow smoothly through every part of the circuit board, avoiding the acid from stagnating in certain areas and causing excessive corrosion.

[0053] Specifically, in the design of the flow path, the acid can form a more uniform flow area on the surface of the circuit board by adding microchannels or eddy current areas. This optimized design not only improves the micro-etching effect, but also reduces the surface treatment quality problems caused by uneven flow of the acid. In some embodiments, a bidirectional flow groove is designed, and the acid flows into one end of the micro-etching groove. After a period of time, it re-covers the other side of the circuit board by reverse flow, thereby further optimizing the distribution of the acid.

[0054] In one possible implementation, in order to ensure that the acid can evenly cover the entire circuit board surface, a circulating flow system can be used in the micro-etching tank. The circulating flow system can continuously refresh the acid by pumping the acid out of the tank and then returning it to the tank, ensuring that every part of the circuit board surface can be exposed to fresh acid. Through the circulating flow, the activity of the acid can be fully utilized, and the efficiency and uniformity of oxide layer removal are significantly improved.

[0055] In some embodiments, the flow of the acid solution not only relies on gravity, but also can be forced to flow by a pumping system. The pumping system can ensure that the flow rate of the acid solution in the micro-etching tank meets the set requirements, avoiding the problem of uneven treatment caused by too low acid flow rate. The power and flow rate of the pumping system can be flexibly adjusted according to different acid types and circuit board specifications to achieve the best micro-etching effect.

[0056] In fluid dynamics optimization, the flow behavior of the acid can be described by the Navier-Stokes equation: Among them, ρ is the density of the acid, v is the velocity field of the acid, t is the time, is the pressure gradient of the acid solution, μ is the dynamic viscosity of the acid solution, is the Laplace operator of the velocity field, and F is the external force term. Through this equation, the flow pattern of the acid in the micro-etching tank can be calculated, and the tank design and acid flow rate can be optimized based on these data.

[0057] By optimizing the fluid dynamics model and the flow path of the acid, this embodiment can ensure that the acid is evenly distributed on the surface of the circuit board, thereby improving the uniformity of oxide layer removal and the treatment effect. At the same time, by designing a reasonable flow path and an appropriate flow rate, local excessive corrosion caused by acid accumulation or uneven flow is avoided. Fluid optimization can also improve the efficiency of the acid reaction, reduce unnecessary energy consumption and reaction time, and make the micro-etching process more efficient.

[0058] In general, the fluid dynamics optimization step in this embodiment ensures the uniform distribution and effective reaction of the acid by precisely controlling the acid flow rate, flow path and contact time with the circuit board surface, providing a uniform and ideal substrate for the subsequent coating adhesion, further improving the quality and consistency of the circuit board surface treatment.

[0059] S5. Optimize the temperature field distribution through the heat conduction model to ensure the uniform temperature of the acid during the micro-etching process; In this embodiment, the design of the temperature control system includes a temperature sensor, a heating device and a control system. Specifically, the temperature of the acid solution is measured by a real-time monitoring sensor, and the temperature control system adjusts the working state of the heating device according to the deviation between the set target temperature and the actual temperature. The goal of the temperature control system is to keep the acid solution temperature between 40°C and 60°C. This temperature range can ensure the best efficiency of the acid solution reaction while avoiding damage or excessive corrosion of the circuit board caused by excessive temperature.

[0060] Generally speaking, too low acid temperature will lead to a slow reaction rate, thus affecting the effect of oxide layer removal, while too high temperature may cause corrosion of the substrate. Therefore, the design of the temperature control system should ensure that the temperature is stable within the set range and should not fluctuate more than ±2°C. Through the precise adjustment of the temperature control system, the temperature stability can be ensured, thereby improving the uniformity and stability of the micro-etching process.

[0061] As an option, to ensure higher accuracy, the temperature control system can adjust the temperature through a closed-loop control mechanism. When the temperature deviates from the set value, the system will respond immediately, adjust the heating device or start the cooling mechanism to quickly return to the preset temperature range. In this process, real-time feedback and the accuracy of adjustment are crucial to improving the efficiency of the entire process.

[0062] Specifically, the temperature control system can be adjusted in a variety of ways, including but not limited to direct heating and a cold-heat exchange system. In some embodiments, by adjusting the temperature of the acid heating pipe and controlling the heat conduction between the circuit board and the heating device, the temperature control system can accurately adjust the temperature of the acid to avoid the influence of temperature fluctuations on the reaction rate of the acid.

[0063] In one possible implementation, in order to further improve the accuracy of the temperature control system, it may be necessary to add a temperature uniformity detection system in the micro-etching tank. The system uses multiple temperature sensors arranged in different positions to monitor the temperature distribution in the entire micro-etching tank in real time. Through real-time analysis of temperature data, it can ensure that the temperature of the acid solution is evenly distributed throughout the tank to avoid local overheating or cooling.

[0064] In some embodiments, the temperature adjustment is not limited to simple operations of heating or cooling. The temperature can also be finely regulated by adjusting the power of the heating device to ensure that the temperature is within the optimal range at all times. For example, by using variable frequency to adjust the power of the heating device, the temperature change can be adjusted more smoothly and the impact of temperature fluctuations can be reduced.

[0065] In order to ensure the accuracy of the temperature control system, the change of the temperature field can be described by the heat conduction equation. According to Fourier's heat conduction law, the change of the temperature field during the heat exchange process is controlled by the following formula: Where T is the temperature of the acid solution, t is the time, α is the thermal diffusion coefficient of the acid solution, is the Laplace operator of temperature, which represents the diffusion behavior of temperature in space. By solving this equation, the temperature field of the acid can be simulated and the temperature control scheme can be further optimized.

[0066] In practical applications, the temperature control system can quickly adjust the power and heating time of the heating device according to the temperature gradient and change rate to ensure that the temperature of the acid is always kept within the optimal range. Especially when the acid flow rate is fast and the reaction time is short, the accuracy of the temperature control system is particularly important, which can ensure the stability of the reaction rate and thus improve the removal effect of the oxide layer.

[0067] The precise adjustment of the temperature control system provides stable reaction conditions for the micro-etching process, avoiding uneven oxide layer removal and excessive corrosion caused by temperature fluctuations. By controlling the temperature within the ideal range, the uniformity and efficiency of the acid reaction can be effectively improved, avoiding substrate damage or excessive acid consumption caused by local overheating. At the same time, precise temperature control provides an ideal base for the adhesion and anti-oxidation effect of subsequent coatings, ensuring the quality and consistency of surface treatment.

[0068] In general, the temperature control system in this embodiment ensures the stability of the micro-etching process and the consistency of the reaction rate by real-time monitoring and adjustment of the acid solution temperature, thereby improving the effect and reliability of the entire surface treatment process.

[0069] S6, drying the micro-etched circuit board to remove residual acid and moisture; In this embodiment, the drying step is mainly achieved by an efficient hot air drying system or a hot internal blowing system. Usually after acid micro-etching, a small amount of acid and moisture will remain on the surface of the circuit board. This moisture needs to be completely removed in a short time to avoid the influence of residual moisture on the subsequent coating quality. Generally, the drying temperature range used is 60°C to 100°C. This temperature range can quickly evaporate moisture without damaging the circuit board material.

[0070] Specifically, in this embodiment, a strong wind heating system can be used in the drying process. By using a strong wind device to blow hot air, the evaporation of moisture on the surface of the circuit board is accelerated. The hot air system can evenly distribute the hot air to every part of the circuit board to ensure that the moisture on each part of the surface can be effectively removed. In some cases, in order to improve the drying efficiency, the wind speed of the hot air system can be adjusted to a certain range (such as 2-3 meters per second) to ensure that the air can take away more moisture when flowing on the surface of the circuit board.

[0071] Generally, the drying process takes about 3 to 5 minutes, depending on the moisture content on the circuit board surface, air flow rate and temperature. Too long a drying time may waste energy, while too short a drying time may result in the failure of complete evaporation of moisture, affecting the adhesion of subsequent coatings. Therefore, the drying time needs to be precisely controlled according to the actual process conditions.

[0072] As an option, a multi-stage heating and drying process can be used, which first uses gentle low-temperature air to remove most of the moisture, and then uses high-temperature air to accelerate the final moisture removal. This method can effectively avoid thermal damage to the circuit board material that may be caused by overheating.

[0073] In one possible implementation, in order to ensure uniform drying, the circuit board can be rotated slightly in the hot air through an automatic rotation system to ensure that every corner is evenly exposed to the hot air. This rotation can effectively avoid the problem of incomplete moisture removal in some areas, thereby improving the effect of the entire drying process.

[0074] In some embodiments, in addition to conventional hot air drying, ultraviolet (UV) lamps may be used to accelerate the evaporation of surface moisture. The UV lamp can increase the temperature of the circuit board surface in a short period of time, allowing the moisture to evaporate quickly, and to a certain extent help remove residual trace acid, further ensuring that the surface is clean and dry.

[0075] In the evaporation process, according to the Clausius-Clapeyron equation, the relationship between water evaporation and temperature and pressure can be described by the following formula: Where P is the vapor pressure, P0 is the standard vapor pressure, ΔH vap is the heat of vaporization of water, R is the gas constant, T is the temperature, and T0 is the initial temperature. By precisely controlling the temperature, the evaporation process of water can be accelerated to ensure complete removal of water.

[0076] The efficient drying system can quickly remove the residual moisture on the circuit board surface, ensuring that the moisture no longer affects the adhesion and uniformity of the subsequent coating. By using hot air drying and UV-assisted drying, it can ensure that every part of the circuit board surface can be fully dried to avoid the problem of local residual moisture. In addition, precise control during the drying process can avoid overheating of the circuit board, thereby protecting the circuit board material from damage.

[0077] In general, the drying process in this embodiment ensures complete removal of moisture from the circuit board surface by optimizing heating and wind speed control. The uniformity and efficiency of the drying process provide an ideal foundation for the subsequent attachment of the anti-oxidation coating, further improving the quality and consistency of the surface treatment.

[0078] S7, coating an anti-oxidation coating on the surface of the circuit board, and curing the coating by heating to fix the coating; In this embodiment, the anti-oxidation coating is usually applied by spraying, dipping or brushing. Spraying is the most common method, and the coating is evenly sprayed onto the surface of the circuit board through a spray gun. According to the size of the circuit board, the thickness requirement of the coating and the production efficiency, a suitable spraying equipment can be selected. During the spraying process, it is necessary to ensure the uniformity of the coating to avoid uneven coating thickness, missing coating or excessive coating thickness. The coating thickness is generally between 5 and 20 microns, and the specific thickness depends on the type of coating material and the circuit board surface protection requirements.

[0079] Generally, the anti-oxidation coating applied usually contains nanoparticles, which can enhance the adhesion and durability of the coating. Nanoparticles have a higher surface energy, which allows the coating to better bond with the surface of the circuit board, reducing the possibility of shedding and cracking. Coatings using nanoparticles can usually significantly improve the anti-oxidation effect, especially in high temperature or high humidity environments, showing better durability.

[0080] As an option, the material of the anti-oxidation coating can be adjusted according to different usage requirements. For example, a coating containing silicone or epoxy resin is used, which not only has good anti-oxidation properties but also provides additional mechanical strength and wear resistance. The choice of coating depends on the use environment of the circuit board and the required protection performance.

[0081] Specifically, after coating, the coating needs to be cured to ensure the hardness and adhesion of the coating. Curing can be done by heating or ultraviolet (UV) irradiation. Typically, the curing temperature is set between 80°C and 120°C, and the curing time is 5 to 15 minutes. During the curing process, the components in the coating will react chemically to form a stable film that enhances its protective function. For UV-cured coatings, the photosensitizer in the coating will initiate a polymerization reaction through ultraviolet irradiation, quickly curing the coating and reducing the curing time.

[0082] In one possible implementation, the curing temperature and time settings may vary depending on the type of coating. For example, when using an epoxy coating, the curing temperature may need to be slightly higher, while when using a silicone coating, a lower temperature and a shorter time may be sufficient. To ensure uniformity of the curing effect, the circuit board can be rotated or tilted appropriately during the curing process to ensure that all surfaces are evenly heated or exposed to UV light.

[0083] In some embodiments, the curing process may also consider using hot air flow acceleration technology to accelerate the curing of the coating by hot air flow. This method can evenly distribute heat to the entire circuit board surface to avoid local overheating or incomplete curing.

[0084] During the coating curing process, the reaction rate of the coating can be described by the Arrhenius equation, and the relationship between the reaction rate and temperature is as follows: Where k is the reaction rate constant, A is the prefactor, and E a is the activation energy, R is the gas constant, and T is the temperature. By adjusting the curing temperature and time, the curing rate of the coating can be optimized to ensure the hardness and adhesion of the coating.

[0085] Through precise coating and curing control, this embodiment can ensure that the coating is uniform, defect-free, and has good adhesion. The anti-oxidation coating not only improves the corrosion resistance of the circuit board, but also extends its service life. The uniformity and adhesion of the coating are guaranteed on the entire circuit board surface, avoiding problems such as coating shedding and cracking. At the same time, the optimization of the curing process ensures the full reaction of the coating, forming a solid protective film and enhancing the protective function of the circuit board. The precise control of this step provides a guarantee for subsequent quality inspection and the stability of the final product performance.

[0086] In summary, the anti-oxidation coating coating and curing steps in this embodiment ensure the uniformity, adhesion and anti-oxidation effect of the coating by precisely controlling the coating method, coating thickness, curing temperature and time, etc., and provide long-term protection for the circuit board. The optimization of these technologies improves the efficiency and quality of the entire surface treatment process and ensures the performance stability and reliability of the circuit board.

[0087] S8. Perform quality inspection on the processed circuit boards to ensure that the surface treatment is uniform and meets quality standards; In this embodiment, the quality inspection process mainly relies on high-precision surface analysis technology. Specifically, a scanning electron microscope (SEM) is used to scan the surface of the circuit board to check the uniformity of the oxide layer removal and the adhesion and thickness of the anti-oxidation coating. By analyzing the SEM image, it can be clearly observed whether the coating is uniform, whether there are cracks, bubbles, shedding or coating missing.

[0088] Generally, SEM scanning can provide high-resolution images of the microstructure of the circuit board surface, helping technicians detect the thickness distribution of the coating and the removal of the oxide layer on the circuit board surface. Usually, the scanning resolution can reach the nanometer level, which can clearly show the surface details. By comparing and analyzing the scanning results, it is possible to evaluate whether the micro-etching treatment is uniform, whether there is excessive local corrosion or poor coating adhesion.

[0089] As an option, in addition to SEM, X-ray photoelectron spectroscopy (XPS) technology can be used to further verify the surface treatment effect. XPS can analyze the changes in the chemical composition of the circuit board surface, accurately determine the degree of removal of the oxide layer and the bonding between the anti-oxidation coating and the circuit board surface. Through XPS testing, the chemical stability of the coating and the bonding between the coating and the substrate can be evaluated, thereby verifying whether the anti-oxidation coating has sufficient protection capabilities.

[0090] Specifically, SEM image analysis combined with XPS data can help technicians fully understand the surface status of the circuit board. Through these technologies, any abnormalities in the coating process can be detected, such as excessive coating thickness, uneven coating, or insufficient adhesion between the coating and the substrate. Through this multiple detection method, it can be ensured that the surface treatment of each batch of circuit boards meets the standard requirements.

[0091] In one possible implementation, quality inspection is not limited to surface scanning, but can also be combined with electrical performance testing to conduct a comprehensive inspection of the circuit board. For example, a current conduction test is used to detect whether the anti-oxidation coating affects the conductivity of the circuit board to ensure that the coating does not interfere with the normal operation of the circuit. Such tests can fully evaluate the effect of the circuit board surface treatment process to ensure that the product meets the actual use requirements.

[0092] In some embodiments, quality inspection can also be performed by an automated optical inspection system (AOI) to detect surface defects. The system automatically scans the surface of the circuit board through a high-speed camera and image processing algorithm to identify any defects or unevenness in the coating. The automated inspection system can greatly improve production efficiency while ensuring the stability of product quality.

[0093] In quality inspection, when performing surface analysis by SEM, the surface roughness formula can be used to quantitatively analyze the uniformity of the coating: Among them, R q is the surface roughness, y(x) is the surface height distribution, and L is the scanning length. By calculating the surface roughness, the uniformity and surface quality of the coating can be quantified, and the adhesion and protective performance of the coating can be further evaluated.

[0094] By using high-precision surface analysis techniques such as SEM, XPS and AOI, the present embodiment can comprehensively detect the effect of the circuit board surface treatment to ensure uniform removal of the oxide layer and high-quality adhesion of the coating. These detection methods can detect potential problems in the process in advance and make timely adjustments to prevent unqualified products from entering the market. Through this precise quality control, the long-term reliability and stability of the circuit board can be improved to ensure that it can work properly under various environmental conditions.

[0095] In summary, the quality inspection step in this embodiment ensures the efficiency and stability of the surface treatment process of each circuit board through high-precision surface analysis and electrical performance testing. The combination of multiple inspection methods provides strong support for the optimization of the entire surface treatment process, further improving the quality and controllability of the final product.

[0096] 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 printed circuit board surface treatment process, characterized in that: The following steps are involved: S1, preparing an acid solution and preheating it to a set temperature, wherein the concentration and temperature of the acid solution are precisely controlled during the micro-etching process; S2. Pre-clean the circuit board to remove impurities and contaminants on its surface to ensure uniformity during micro-etching; S3, immersing the cleaned circuit board in a precisely controlled acid solution, and performing micro-etching treatment under set temperature, acid concentration and time conditions; S4. During the micro-etching process, the acid flow rate and distribution are optimized through the fluid dynamics model to ensure that the acid evenly covers the circuit board surface; S5. Optimize the temperature field distribution through the heat conduction model to ensure the uniform temperature of the acid during the micro-etching process; S6, drying the micro-etched circuit board to remove residual acid and moisture; S7, coating an anti-oxidation coating on the surface of the circuit board, and curing the coating by heating to fix the coating; S8. Perform quality inspection on the processed circuit boards to ensure that the surface treatment is uniform and meets quality standards.

2. A printed circuit board surface treatment process according to claim 1, characterized in that: The preheating temperature of the acid solution is between 40°C and 80°C.

3. A printed circuit board surface treatment process according to claim 1, characterized in that: The concentration of the acid solution is between 5% and 30%, and the concentration of the acid solution is monitored and adjusted in real time during the micro-etching process to ensure the reactivity of the acid solution during the micro-etching process.

4. A printed circuit board surface treatment process according to claim 1, characterized in that: The reaction temperature during the micro-etching process is monitored in real time by an intelligent temperature control system and maintained between 40° C. and 60° C. to ensure uniform removal of the oxide layer.

5. A printed circuit board surface treatment process according to claim 1, characterized in that: The fluid dynamics model uses computational fluid dynamics simulation to optimize the flow rate and flow path of the acid solution to ensure that the acid solution is evenly distributed on the surface of the circuit board and the flow rate is controlled between 1 and 5 meters per second.

6. A printed circuit board surface treatment process according to claim 1, characterized in that: The anti-oxidation coating uses an antioxidant containing nanoparticles. The adhesion of the coating is improved by more than 10% compared with the traditional coating, and the curing temperature is 80° C. to 120° C. and the curing time is 5 to 15 minutes.

7. A printed circuit board surface treatment process according to claim 1, characterized in that: The micro-etching step simulates the dissolution reaction between the acid solution and the circuit board surface and precisely adjusts the reaction time to ensure uniform removal of the oxide layer. The reaction time is controlled between 5 seconds and 60 seconds.

8. A printed circuit board surface treatment process according to claim 1, characterized in that: The temperature control system automatically adjusts the acid temperature based on real-time sensor data to ensure that the temperature does not vary by more than ±2°C within the set range to avoid adverse effects of temperature fluctuations on the reaction rate.

9. A printed circuit board surface treatment process according to claim 1, characterized in that: The quality inspection is performed by scanning the surface of the circuit board with a scanning electron microscope to analyze the uniformity of oxide layer removal and the adhesion of the anti-oxidation coating, and the process parameters are adjusted according to the inspection results to ensure that each batch of products meets the quality standards.

10. A printed circuit board surface treatment process according to claim 1, characterized in that: The components of the acid solution include sulfuric acid, chloride, fluoride or other chemical solutions suitable for removing oxides on the surface of PCB, and the pH value of the acid solution is between 1 and 3.

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