Electroplating process

Abstract

The invention relates to the technical field of electroplating, and particularly discloses an electroplating process which comprises the following steps: removing attachments on the surface of a to-be-electroplated workpiece in an ultrasonic cold removal and ultrasonic chemical oil removal manner, and activating the to-be-electroplated workpiece by using dilute acid to remove a residual oxide layer and tiny flaws on the surface of the workpiece; the workpiece to be electroplated is uniformly and quickly placed in an electroplating bath for centrifugal nickel electroplating treatment, so that a uniform nickel plating layer is formed on the surface of the workpiece to be electroplated; after electroplating is completed, the workpiece is rapidly taken out of the electroplating bath and placed in gold plating liquid, and centrifugal gold pre-plating treatment is conducted twice in sequence; forming a gold-plated layer on the surface of the workpiece; and finally, carrying out centrifugal spin-drying and drying treatment to obtain an electroplated workpiece finished product, and carrying out quality detection on the dried electroplated workpiece finished product to ensure that the quality of a plating layer meets the requirement. Through centrifugal gold pre-plating treatment, the binding force between the gold plating layer and the nickel plating layer is improved, the uniformity of the plating layer is enhanced, and the corrosion resistance of the plating layer is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electroplating, and in particular to an electroplating process. Background Art

[0002] The traditional electroplating process mainly uses electrochemical reactions to produce metal ions at the anode through oxidation reactions, which are then transported to the cathode through the electrolyte, where they undergo a reduction reaction with the cathode surface and deposit to form a metal coating. However, the traditional electroplating process has problems such as long plating time, poor coating uniformity, and large amounts of electrolyte used, which limits its application in certain high-precision and high-requirement fields.

[0003] In order to solve the above problems, the industry began to explore the use of centrifugal force to assist the electroplating process. The centrifugal electroplating process separates the electrolyte solution into two phases through the centrifugal force generated by the rotating centrifuge, and the electrode is placed on the interface between the two phases to complete the electroplating process. The centrifugal force not only accelerates the migration speed of ions in the solution, but also improves the uniformity of the electrode surface, reduces the generation of bubbles, and thus improves the quality of the coating. The centrifugal electroplating process has several significant advantages. First, due to the action of centrifugal force, the migration speed of metal ions in the solution is accelerated, which increases the deposition rate of the coating and significantly reduces the electroplating time. Secondly, the centrifugal force makes the electroplating solution more evenly distributed on the electrode surface, reduces the unevenness of the coating thickness, and improves the quality and consistency of the coating. In addition, centrifugal electroplating can also reduce the use of electrolyte, reduce processing costs, and reduce the treatment and discharge of waste liquid, which is more environmentally friendly.

[0004] However, the workpieces after gold plating by the existing centrifugal electroplating process are not good. For example, the gold plating is prone to discoloration, peeling, bulging and discoloration. Summary of the invention

[0005] In order to solve the problems of discoloration, peeling, bulging and discoloration on the surface of existing electroplated workpieces, the present application provides an electroplating process, which uses centrifugal pre-gold plating treatment to improve the bonding strength between the gold plating layer and the nickel plating layer, enhance the uniformity of the plating layer, improve the corrosion resistance of the plating layer, and reduce the discoloration, peeling, bulging and discoloration on the surface of the electroplated workpiece.

[0006] This application achieves the above invention objectives through the following technical solutions: An electroplating process, comprising: using ultrasonic cold stripping and ultrasonic chemical degreasing to remove the attachments on the surface of a first workpiece to be electroplated, to obtain a second workpiece to be electroplated; using dilute acid to activate the second workpiece to be electroplated, to remove the residual oxide layer and tiny defects on the surface of the second workpiece to be electroplated, to obtain a third workpiece to be electroplated; using a centrifugal feeding device, to evenly and quickly place the third workpiece to be electroplated in an electroplating tank; wherein an appropriate amount of electroplating nickel liquid mixed with accompanying plating steel beads is added to the electroplating tank; turning on the power supply, and performing centrifugal nickel electroplating treatment, so that a uniform nickel plating layer is formed on the surface of the third workpiece to be electroplated; after the electroplating is completed, using a centrifugal discharging device, the workpiece is quickly taken out of the electroplating tank to obtain a first workpiece to be gold-plated; the first The workpiece to be gold-plated is placed in a gold-plating liquid, and a centrifugal pre-gold-plating treatment is performed to obtain a second workpiece to be gold-plated, so as to improve the bonding force between the gold-plated layer and the nickel-plated layer; the second workpiece to be gold-plated is placed in a gold-plating liquid again, and a centrifugal gold-plating treatment is performed, so that a gold-plated layer is formed on the surface of the second workpiece to be gold-plated, and a first gold-plated workpiece is obtained; the first gold-plated workpiece is placed in a centrifugal drying device, and a centrifugal drying treatment is performed to remove the plating liquid on the surface of the first gold-plated workpiece, and a second gold-plated workpiece is obtained; the second gold-plated workpiece is placed in a drying device, and a drying treatment is performed to ensure that the coating on the surface of the second gold-plated workpiece is completely dried and solidified, and a finished electroplated workpiece is obtained, and a quality inspection is performed on the finished electroplated workpiece after drying to ensure that the coating quality meets the requirements.

[0007] Preferably, ultrasonic cold stripping and ultrasonic chemical degreasing are used to remove the attachments on the surface of the first workpiece to be electroplated to obtain the second workpiece to be electroplated, including: placing the first workpiece to be electroplated in an ultrasonic cleaning machine, using the vibration of ultrasonic waves to quickly detach the attachments on the surface of the first workpiece to be electroplated in a low temperature environment, providing a clean workpiece surface for subsequent processes, and obtaining a fourth workpiece to be electroplated; placing the fourth workpiece to be electroplated in an ultrasonic cleaning solution containing a degreasing agent, using the vibration and cavitation of ultrasonic waves to accelerate the decomposition and removal of oil stains on the surface of the fourth workpiece by the degreasing agent, further improving the cleanliness of the workpiece surface, and obtaining the second workpiece to be electroplated.

[0008] Preferably, the second workpiece to be electroplated is activated with a dilute acid to remove residual oxide layers and tiny defects on the surface of the second workpiece to be electroplated to obtain a third workpiece to be electroplated, including: using an acidic solution to dissolve oxides and rust on the surface of the second workpiece to be electroplated to expose a clean metal surface to obtain a fifth workpiece to be electroplated; then passivating the fifth workpiece to be electroplated to form a stable oxide protective layer on the surface of the substrate to obtain a sixth workpiece to be electroplated; using a dilute acid to activate the substrate of the sixth workpiece to be electroplated at an activation temperature of 25°C to 35°C to remove residual oxides and tiny contaminants on the surface of the sixth workpiece to be electroplated, ensuring that the substrate surface of the sixth workpiece to be electroplated is completely clean and active, to obtain a third workpiece to be electroplated.

[0009] Preferably, the dilute acid is a sulfuric acid solution with a mass fraction of 9.5% to 10.5% or a hydrochloric acid solution with a mass fraction of 9.5% to 10.5%.

[0010] Preferably, the pH value of the nickel electroplating solution is 9.5-11.1.

[0011] Preferably, the temperature of the centrifugal gold plating treatment is 55-65° C., the current is 1.5-5A, and the duration is 55-65 minutes.

[0012] Preferably, the quality inspection of the finished electroplated workpiece comprises: using a line scan camera to collect images to be inspected at various angles of the finished electroplated workpiece; removing salt and pepper noise and Gaussian noise in the image to be inspected by a pre-constructed and trained deep convolutional neural network denoising model to obtain a first image; wherein, areas where salt and pepper noise and Gaussian noise exist in the collected sample image are marked, and the deep convolutional neural network denoising model is trained by using the marked sample image, and the deep convolutional neural network denoising model outputs an image with the salt and pepper noise and Gaussian noise removed; performing illumination intensity optimization correction processing on the first image by an illumination correction algorithm to obtain a second image; and obtaining a feature extraction model by a pre-constructed and trained deep convolutional neural network. Take the texture, shape and color features in the image to be detected; map the texture, shape and color features into texture feature vectors, shape feature vectors and color feature vectors; use the principal component analysis method and the mutual information feature screening method to screen out the target texture feature vectors, target shape feature vectors and target color feature vectors that meet the preset defect characteristics; wherein the defect characteristics include peeling, pitting, flaking and cracking on the surface of the electroplating layer; input the target texture feature vectors, target shape feature vectors and target color feature vectors into a pre-built and trained support vector quality detection model to detect whether the finished electroplated workpiece has quality defects; and automatically classify the defective electroplated workpieces with quality defects and the qualified electroplated workpieces without quality defects through a screening device.

[0013] Preferably, the first image is subjected to illumination intensity optimization correction processing by an illumination correction algorithm to obtain a second image, including: using an illumination intensity calculation formula to calculate illumination intensity correction values ​​of pixels in the first image, and using the illumination intensity correction values ​​as actual illumination intensity values ​​of pixels in the first image, thereby completing illumination intensity optimization correction processing of all pixels in the first image to obtain a second image; wherein the illumination intensity calculation formula is as follows: ; in, Represents the ambient light constant; represents the diffusion coefficient; represents a pixel value of a pixel in the first image; represents the distance decay function, , and denote the coefficients for adjusting row and column influences, respectively. Represents the distance between the pixel and the light source. represents the row position of the pixel in the first image, represents the column position of the pixel in the first image; Represents the directional coefficient, which is used to adjust the contribution weight of directional light to light intensity; represents the directional light function, and Represents the angle between the light source direction and the normal direction of the pixel surface; represents the specular reflection coefficient; represents the specular reflection function, Indicates the roughness of a pixel.

[0014] The present invention performs pre-gold plating on a first workpiece to be gold-plated to obtain a second workpiece to be gold-plated, and then places the second workpiece to be gold-plated in a gold plating solution for centrifugal gold plating, thereby forming a gold-plated layer on the surface of the second workpiece to be gold-plated; the pre-gold plating forms a thin pre-gold layer on the surface of the first workpiece to be gold-plated, and since the pre-gold layer can form good chemical bonding or physical adsorption with both the nickel layer and the gold layer, it plays a role of a "bridge", so the pre-gold layer can not only improve the bonding force with the nickel plating layer, but also help to improve the bonding force with the subsequent gold layer; make the plating more firm and not easy to fall off; at the same time, since the pre-gold layer is extremely thin and uniform, it can provide a flat and uniform deposition surface for the subsequent plating. In this way, during centrifugal gold plating, the gold layer can be more evenly deposited on the nickel layer, thereby obtaining a more uniform and smooth plating; therefore, the pre-gold plating can further enhance the uniformity of the plating; in addition, the pre-gold layer can effectively prevent oxidation and corrosion of the metal surface, so that the plating of the final workpiece to be gold-plated has good corrosion resistance. In addition, nickel plating is performed before centrifugal gold plating, which can form a uniform nickel layer on the surface of the workpiece, and this nickel layer has good bonding strength with the substrate. When gold or other metals are electroplated later, the coating can be more firmly attached to the pre-nickel layer, thereby improving the bonding strength of the overall coating. This helps to reduce the risk of the coating falling off or peeling off during use, and improves the reliability and service life of the plated parts. Therefore, when the workpiece after electroplating is inspected, the probability of discoloration, peeling, bulging and discoloration is greatly reduced, which is conducive to improving the corrosion resistance of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of an electroplating process flow provided in Example 1 of the present invention; Figure 2 A schematic diagram of the process of quality inspection of finished electroplated workpieces provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0016] To make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all the embodiments. The components of the embodiment of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiment of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but only represents the selected embodiment of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present application, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first", "second" and the like appear in the description of the present application, they are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, if the terms "horizontal", "vertical" and the like appear in the description of the present application, it does not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0017] Please refer to Figure 1 , Figure 1 A schematic diagram of an electroplating process flow is provided in an embodiment of the present invention, wherein the electroplating process comprises the following steps: S101, using ultrasonic cold stripping and ultrasonic chemical degreasing to remove the attachments on the surface of the first workpiece to be electroplated to obtain a second workpiece to be electroplated.

[0018] The specific implementation method may be as follows: placing the first workpiece to be electroplated in an ultrasonic cleaning machine, using the vibration of ultrasonic waves to quickly remove the attachments on the surface of the first workpiece to be electroplated in a low temperature environment, obtaining a fourth workpiece to be electroplated with a clean surface, and providing a clean workpiece surface for subsequent processes. Then, placing the fourth workpiece to be electroplated in an ultrasonic cleaning solution containing a degreasing agent, using the vibration and cavitation of ultrasonic waves to accelerate the decomposition and removal of oil stains on the surface of the fourth workpiece to be electroplated by the degreasing agent, further improving the cleanliness of the workpiece surface, and obtaining a second workpiece to be electroplated.

[0019] In an embodiment of the present application, in order to prevent the first workpiece to be electroplated from being damaged by heat and causing performance damage, the ultrasonic cleaning temperature is controlled within the range of 0 to 5°C, so that the first workpiece to be electroplated can quickly detach from the attachments on its surface in a low temperature environment within this temperature range.

[0020] S102, performing activation treatment on the second workpiece to be electroplated using a dilute acid to remove residual oxide layers and minor defects on the surface of the second workpiece to be electroplated, thereby obtaining a third workpiece to be electroplated.

[0021] The specific implementation method may be: using an acidic solution to dissolve the oxides and rust on the surface of the second workpiece to be electroplated, exposing a clean metal surface, and obtaining a fifth workpiece to be electroplated; then passivating the fifth workpiece to be electroplated so that a stable oxide protective layer is formed on the surface of the substrate to obtain a sixth workpiece to be electroplated; using dilute acid to activate the substrate of the sixth workpiece to be electroplated, the activation temperature is 25°C to 35°C, so as to remove the residual oxides and tiny pollutants on the surface of the sixth workpiece to be electroplated, and ensure that the substrate surface of the sixth workpiece to be electroplated is completely clean and active, and obtain the third workpiece to be electroplated. Wherein, the dilute acid: a sulfuric acid solution with a mass fraction of 9.5% to 10.5% or a hydrochloric acid solution with a mass fraction of 9.5 to 10.5%. By utilizing the corrosive effect of sulfuric acid solution or hydrochloric acid solution, the residual oxide layer and tiny defects on the surface of the workpiece are removed, which is beneficial to improve the activity of the surface of the workpiece to be electroplated and the wettability of the electroplating solution.

[0022] S103, using a centrifugal loading device to evenly and quickly place the third workpiece to be electroplated in the electroplating tank.

[0023] Wherein, a proper amount of nickel electroplating solution mixed with 40 ml of accompanying plating steel beads is added into the electroplating tank; the pH value of the nickel electroplating solution is 9.5-11.1.

[0024] In some feasible embodiments, the electroplating nickel solution is also magnetized by a magnetizing device, so that the magnetism of the electroplating nickel solution is gradually weakened until it disappears. After magnetization, the ions inside the electroplating nickel solution will show magnetic polarity, so that the energy of ion precipitation is reduced and it is easier to orient. This helps to reduce the porosity of the coating, thereby making the surface structure of the coating denser. At the same time, the magnetization can enhance the bonding force between the coating and the substrate. Because the effect of the magnetic field makes it easier for the coating ions to form a firm bond with the substrate surface during the deposition process, the subsequent plated layer is more firm and stable, which helps to improve the overall quality of the coating.

[0025] By adjusting the rotation speed of the centrifugal feeding equipment engine, the feeding speed is adjusted. A threshold is set according to the actual application scenario. When the speed is adjusted to be greater than the threshold, the third workpiece to be electroplated can be placed in the electroplating tank evenly and quickly.

[0026] S104, turning on the power of the electroplating tank, and performing centrifugal nickel electroplating on the third workpiece to be electroplated, so that a uniform nickel plating layer is formed on the surface of the third workpiece to be electroplated.

[0027] During the whole process of centrifugal nickel electroplating treatment, the pH value of the nickel electroplating solution is controlled to be maintained at 9.5-11.1.

[0028] S105, after the nickel electroplating treatment is completed, the workpiece is quickly taken out from the electroplating tank by using a centrifugal discharging device to obtain a first workpiece to be gold-plated.

[0029] By adjusting the speed of the centrifugal discharging equipment engine, the discharging speed is adjusted. A threshold value can be set according to the actual application scenario. When the speed is adjusted to be greater than the threshold value, the first workpiece to be gold-plated can be quickly taken out of the electroplating tank.

[0030] S106, placing the first workpiece to be gold-plated in a gold-plating solution, and performing a centrifugal pre-gold plating treatment to obtain a second workpiece to be gold-plated.

[0031] The first workpiece to be gold-plated is pre-gold-plated to obtain the second workpiece to be gold-plated, and then the second workpiece to be gold-plated is placed in the gold-plating liquid again for centrifugal gold-plating, so that a gold-plated layer is formed on the surface of the second workpiece to be gold-plated; the pre-gold-plating treatment forms a thin pre-gold layer on the surface of the first workpiece to be gold-plated, and since the pre-gold layer can form good chemical bonding or physical adsorption with the nickel layer and the gold layer, it plays a role of a "bridge", so the pre-gold layer can not only improve the bonding force with the nickel plating layer, but also help to improve the bonding force with the subsequent gold layer; make the plating more firm and not easy to fall off; at the same time, since the pre-gold layer is extremely thin and uniform, it can provide a flat and uniform deposition surface for the subsequent plating. In this way, during centrifugal gold plating, the gold layer can be more evenly deposited on the nickel layer, so as to obtain a more uniform and smooth plating; therefore, the pre-gold plating treatment can further enhance the uniformity of the plating; in addition, the pre-gold layer can effectively prevent oxidation and corrosion of the metal surface, so that the plating of the final workpiece to be gold-plated has good corrosion resistance.

[0032] S107, placing the second workpiece to be gold-plated in the gold-plating liquid again, and performing centrifugal gold-plating treatment, so that a gold-plated layer is formed on the surface of the second workpiece to be gold-plated, and a first gold-plated workpiece is obtained.

[0033] The temperature of the centrifugal gold plating treatment is 55-65° C., the current is 1.5-5A, the duration is 55-65 minutes, and the speed of the centrifugal electroplating equipment is controlled to be 210 revolutions per minute.

[0034] S108, placing the first gold-plated workpiece in a centrifugal drying device to perform a centrifugal drying process to remove the electroplating liquid on the surface of the gold-plated workpiece to obtain a second gold-plated workpiece.

[0035] S109, placing the second gold-plated workpiece in a drying device for drying to ensure that the plating layer on the surface of the second gold-plated workpiece is completely dried and solidified to obtain a finished electroplated workpiece.

[0036] S110, performing quality inspection on the finished electroplated workpiece after drying to ensure that the quality of the coating meets the requirements.

[0037] S111, the finished electroplated workpiece that has passed the quality inspection is subjected to magnetic field inspection using a magnetic field inspection instrument to determine the strength and distribution of its magnetism.

[0038] S112, selecting a suitable demagnetization device according to the material, size and magnetic strength of the finished electroplated workpiece; after setting the demagnetization parameters, placing the finished electroplated workpiece in the demagnetization device and performing demagnetization according to the set parameters.

[0039] During the demagnetization process, the high-frequency changing magnetic field will destroy the magnetic domain structure inside the electroplated workpiece, causing its magnetism to gradually weaken until it disappears.

[0040] Based on experimental examples: Experiment 1: The pH value of the nickel electroplating solution is 9.5, the temperature of the centrifugal gold plating treatment is 55°C, the current of the centrifugal gold plating treatment is 1.5A, the speed of the centrifugal electroplating equipment is controlled to be 210 revolutions per minute, and the gold plating duration is 64 minutes.

[0041] Experiment 2: The pH value of the nickel electroplating solution is 9.5, the temperature of the centrifugal gold plating treatment is 60°C, the current of the centrifugal gold plating treatment is 5A, the speed of the centrifugal electroplating equipment is controlled to be 210 revolutions per minute, and the gold plating duration is 61 minutes.

[0042] Experiment 3: The pH value of the nickel electroplating solution is 9.5, the temperature of the centrifugal gold plating treatment is 65°C, the current of the centrifugal gold plating treatment is 3A, the speed of the centrifugal electroplating equipment is controlled to be 210 revolutions per minute, and the gold plating duration is 60 minutes.

[0043] Experiment 4: The pH value of the nickel electroplating solution is 10, the temperature of the centrifugal gold plating treatment is 65°C, the current of the centrifugal gold plating treatment is 4A, the speed of the centrifugal electroplating equipment is controlled to be 210 revolutions per minute, and the gold plating duration is 60 minutes.

[0044] Comparative Example 1: Reduce step S110 and step S111, and the pH value of the nickel electroplating solution is 9.5, the temperature of the centrifugal gold plating treatment is 55°C, the current of the centrifugal gold plating treatment is 1.5A, the speed of the centrifugal electroplating equipment is controlled to 210 revolutions per minute, and the gold plating duration is 64 minutes.

[0045] Comparative Example 2: Based on Comparative Example 1, step S103 and step S104 are reduced, that is, the workpiece is directly gold-plated without going through the nickel electroplating step, and the temperature of the centrifugal gold plating treatment is 55°C, the current of the centrifugal gold plating treatment is 1.5A, the speed of the centrifugal electroplating equipment is controlled to 210 revolutions per minute, and the gold plating duration is 64 minutes.

[0046] The electroplating operations were carried out through the above-mentioned Experiment 1 to Comparative Example 2, and the experimental effects were verified on the workpieces after electroplating. The methods for verifying the experimental effects include: bending 10 pieces after plating, baking at 300°C (10 minutes), baking at 200°C (60 minutes) + bending 10 pieces, and appearance inspection, as shown in Table 1 below: Table 1 It can be seen that by pre-nickel plating the workpiece to be electroplated during centrifugal electroplating, a uniform nickel layer can be formed on the surface of the workpiece, and there is good bonding between this nickel layer and the substrate. When electroplating gold or other metals is performed subsequently, the coating can be more firmly attached to the pre-nickel layer, thereby improving the bonding strength of the overall coating. This helps to reduce the risk of the coating falling off or peeling off during use, and improves the reliability and service life of the plated parts. Thus, when the workpiece after electroplating is detected, the probability of discoloration, peeling, bulging and discoloration is greatly reduced. Further, the magnetized plating solution can enhance the movement of ions in the plating solution, so that the ions are more evenly deposited on the surface of the workpiece during the electroplating process. This helps to reduce the problem of uneven coating thickness, especially in the special process of centrifugal electroplating, the magnetized plating solution can further improve the uniformity of the coating, so that the coating can obtain good coverage in all directions. The magnetized plating solution can also improve the physical and chemical properties of the plating solution, such as reducing the viscosity of the plating solution, improving the conductivity of the plating solution, etc. The optimization of these properties helps to further improve the quality and efficiency of electroplating, making the coating more uniform, smooth and bright.

[0047] like Figure 2 As shown, in some feasible implementations, quality inspection of the finished electroplated workpiece specifically includes the following steps: S201, using a line scan camera to collect images to be inspected at various angles and orientations of the electroplated workpiece product.

[0048] In an embodiment of the present invention, a high-speed line scanning camera system with adjustable scanning speed and resolution is selected, and the system is composed of a high-speed moving line scanning camera, a light source and a motion control device. First, the size, shape and structure of the electroplated workpiece to be inspected are measured and analyzed using measuring tools such as calipers and microscopes. Then, the scanning path and parameter settings are determined according to the size, shape and structural characteristics of the electroplated workpiece. For example, according to the structural characteristics of the electroplated workpiece, a suitable scanning path is selected to ensure that the surface of the electroplated layer of the electroplated workpiece can be fully scanned; according to the size and shape of the electroplated workpiece, the scanning speed and resolution of the line scanning camera are adjusted to ensure that the continuous image of the electroplated layer of the electroplated workpiece is obtained as quickly as possible without losing details. Generally speaking, for a slender electroplated workpiece, a lower scanning speed and a higher resolution can be selected to ensure that more details can be captured. For a thicker and shorter electroplated workpiece, a higher scanning speed and a lower resolution can be selected to improve the detection efficiency.

[0049] When collecting images, the finished electroplated workpiece is placed on the above-mentioned motion control device, and the above-mentioned high-speed line scanning camera system is started; the high-speed moving line scanning camera scans the finished electroplated workpiece, and the continuous images of the finished electroplated workpiece can be quickly obtained, and the images are transmitted to the computer for processing and analysis, which can ensure the dimensional accuracy and surface quality of the finished electroplated workpiece. Among them, the motion control device is used to control the moving speed of the finished electroplated workpiece to match the acquisition speed of the line scanning camera. According to the production speed of the finished electroplated workpiece and the frame rate of the camera, a suitable moving speed is set to ensure the clarity and continuous acquisition of the image. It should be noted that a plurality of the above-mentioned high-speed line scanning camera systems are set and installed at various positions of the finished electroplated workpiece to scan and obtain the images to be detected at various angles and positions of the finished electroplated workpiece. Specifically, a suitable shooting position is set on the production line to ensure that each angle of the finished electroplated workpiece can be clearly photographed. For each finished electroplated workpiece, multiple groups of images are collected from different angles and different lighting conditions to increase the diversity of the data. For example, shooting from the front, side, top and other angles, while adjusting the light intensity and angle, to collect images under different lighting conditions. In some feasible implementations, the collected images can also be verified and analyzed to evaluate the optimization effect of the acquisition parameters. If necessary, the acquisition parameters can be further adjusted to improve the image quality and detection accuracy. In addition, the light source in the above-mentioned high-speed line scanning camera system can use a uniform white LED light source. By adjusting the brightness and angle of the light source, the illumination of the surface of the electroplated workpiece is ensured to be uniform, and shadows and reflections are reduced to ensure that the surface of the electroplated workpiece can be clearly illuminated, so that the image of the electroplated layer can be clearly captured.

[0050] S202, removing salt and pepper noise and Gaussian noise in the image to be detected by using a pre-built and trained deep convolutional neural network denoising model to obtain a first image.

[0051] First, the deep convolutional neural network denoising model is constructed using DnCNN (Deep Convolutional Neural Network for Image Denoising). DnCNN has shown excellent performance in image denoising and can effectively remove various types of noise while retaining the details and structural information of the image; after proper training, DnCNN can have good generalization ability for different types of images and noise, and is suitable for various practical application scenarios; DnCNN can automatically learn the denoising pattern and rules from the training data through end-to-end learning; in addition, DnCNN has relatively high computational efficiency and can quickly process large-scale image data, which is conducive to improving the quality inspection efficiency of electroplated workpieces. Then, by collecting sample images, the collection of sample images can refer to the collection method of the above-mentioned image to be detected, which will not be repeated here.

[0052] Then, the areas with salt and pepper noise and Gaussian noise in the collected sample images are annotated manually, for example, the areas with salt and pepper noise and Gaussian noise are marked with specific colors or labels; then the annotated sample images with salt and pepper noise and Gaussian noise and normal images are divided into training sets, validation sets and test sets.

[0053] The training set is input into the deep convolutional neural network denoising model for training, and the weights and parameters of the network are continuously adjusted through the back propagation algorithm, so that the network can learn different noise characteristics and denoising methods; after multiple iterations of training, the deep convolutional neural network denoising model can identify the noise characteristics in the sample image, and automatically remove these noises to restore clear image details; the deep convolutional neural network denoising model outputs an image after the marked salt and pepper noise and Gaussian noise have been removed, thereby achieving denoising processing of the sample image, and the image becomes clearer. The deep convolutional neural network denoising model is then verified and tested using the validation set and the test set.

[0054] Finally, the image to be detected is input into the deep convolutional neural network denoising model that has been trained, verified and tested, and a first image from which salt and pepper noise and Gaussian noise have been removed is output.

[0055] S203: Perform illumination intensity optimization correction processing on the first image using an illumination correction algorithm to obtain a second image.

[0056] The illumination intensity calculation formula is used to calculate the illumination intensity correction value of the pixel points in the first image, and the illumination intensity correction value is used as the actual value of the illumination intensity of the pixel points in the first image, thereby completing the illumination intensity optimization correction processing of all pixel points in the first image to obtain the second image.

[0057] The calculation formula of light intensity is as follows: ; in, Represents the ambient light constant; represents the diffusion coefficient; represents a pixel value of a pixel in the first image; represents the distance decay function, , and denote the coefficients for adjusting row and column influences, respectively. Represents the distance between the pixel and the light source. represents the row position of the pixel in the first image, represents the column position of the pixel in the first image; Represents the directional coefficient, which is used to adjust the contribution weight of directional light to light intensity; represents the directional light function, and Represents the angle between the light source direction and the normal direction of the pixel surface; represents the specular reflection coefficient; represents the specular reflection function, Indicates the roughness of a pixel.

[0058] The embodiment of the present invention can increase the illumination intensity of the area in the image that appears darker due to uneven illumination through the illumination correction algorithm, so that it is more consistent with the illumination of the surrounding area. By effectively using the denoising algorithm driven by deep learning and the illumination correction algorithm based on the physical model to pre-process the collected images of the electroplated workpiece at various angles and directions to be inspected, the image quality is improved, providing a better basis for the subsequent detection of whether the electroplated workpiece has quality defects.

[0059] S204, extracting texture, shape and color features in the image to be detected through a pre-built and trained deep convolutional neural network feature extraction model; mapping the texture, shape and color features into texture feature vectors, shape feature vectors and color feature vectors; using a principal component analysis method and a mutual information feature screening method to screen out target texture feature vectors, target shape feature vectors and target color feature vectors that meet preset defect features; wherein the defect features include peeling, pitting, flaking and cracks on the surface of the electroplating layer.

[0060] First, a feature extraction model based on a deep convolutional neural network architecture is constructed, and a deep convolutional neural network architecture suitable for multispectral image feature extraction is selected, such as ResNet (Residual Network), DenseNet (Dense Connection Network), etc. These network architectures perform well in image classification and feature extraction, and can effectively extract multi-level features in multispectral images. As above, after the collected sample image is preprocessed by denoising and illumination correction, the corresponding multispectral sample image is obtained; the specific implementation method can refer to the above steps S201 to S203, which will not be repeated here. Then, the characteristic areas and defect categories related to the preset common quality defects of the finished electroplated workpiece in the multispectral sample image are marked, and the common quality defect features of the finished electroplated workpiece are marked, such as peeling, pitting, flaking and cracking, and normal areas. The labeled multispectral sample image is input into the feature extraction model for training, and the feature extraction model is optimized using the random gradient descent algorithm; the feature extraction model automatically extracts the texture, shape and color features of multiple levels in the multispectral image to be detected; at the same time, the texture, shape and color features output by the feature extraction model are weighted by combining the spatial attention mechanism and the channel attention mechanism, and the importance weights of different areas in the image can be automatically learned, so that the feature extraction model can focus on the feature areas related to the preset common quality defects of the finished electroplated workpiece, and improve the accuracy of defect detection. Among them, the texture feature can be extracted by the convolution layer of the feature extraction model, such as extracting the edge, texture and other information in the image. The shape feature can be extracted by the pooling layer and the fully connected layer of the feature extraction model, such as extracting the shape and contour of the object in the image. The color feature can be extracted by the input layer and the convolution layer of the feature extraction model, such as extracting the color distribution, color contrast and other information in the image. During the model training process, the parameters of the attention mechanism are continuously adjusted by the back propagation algorithm so that it can better adapt to the characteristics and defect patterns of the above-mentioned image to be detected.

[0061] At the same time, the thickness and conductivity of the electroplating layer of the finished electroplated workpiece to be tested are extracted by feature engineering methods. Specifically, professional measuring equipment, such as a coating thickness meter, a conductivity tester, etc., are used to measure the thickness and conductivity of the electroplating layer of each finished electroplated workpiece. It can be understood that if it is in the model training stage, the corresponding electroplating layer thickness and conductivity of the electroplated workpiece sample are extracted by feature engineering methods; in order to make the model training effect better and more accurate, the measured physical property data is associated with its corresponding multispectral sample image to establish a one-to-one relationship. For example, a unique identification code can be assigned to each electroplated workpiece sample, and its multispectral sample image and its corresponding physical property data (electroplating layer thickness and conductivity) can be associated with this identification code.

[0062] S205, inputting the target texture feature vector, the target shape feature vector and the target color feature vector into a pre-built and trained support vector quality detection model to detect whether the electroplated workpiece has quality defects; and automatically classifying the defective electroplated workpieces with quality defects and the qualified electroplated workpieces without quality defects through a screening device.

[0063] The plating layer thickness is taken as a one-dimensional feature vector, namely, the plating layer thickness feature vector, and the conductivity is taken as a one-dimensional feature vector, namely, the conductivity feature vector. The plating layer thickness feature vector and the conductivity feature vector are also taken as inputs of the feature extraction model. The last layer of the feature extraction model also includes a fully connected layer, which maps the extracted texture, shape and color features to a feature vector of a preset length to obtain a texture feature vector, a shape feature vector and a color feature vector; the texture feature vector, the shape feature vector, the color feature vector and the plating layer thickness feature vector are fused through the fully connected layer of the feature extraction model, and the texture feature vector, the shape feature vector, the color feature vector and the conductivity feature vector are fused; the fully connected layer of the feature extraction model outputs the fusion vector of the multi-spectral image to be detected.

[0064] The principal component analysis (PCA) method is used to reduce the dimension of the fusion vector; then the mutual information-based feature screening method is used to calculate the mutual information between the fusion vector after dimension reduction and the preset common defect categories (or features) of the finished electroplated workpiece, and the qualified fusion vector is selected by the preset mutual information threshold, that is, all fusion vectors greater than or equal to the mutual information threshold are used as the fusion feature vector of the multispectral sample image. The feature dimension reduction technology is used to reduce the dimension of the feature, improve the quality and interpretability of the feature, and then the feature screening method based on mutual information is used to screen out the fusion vector that is closer to the common defect categories (or features) of the finished electroplated workpiece, which is conducive to further improving the accuracy of defect detection. To summarize, the trained feature extraction model is finally used to extract the multi-level features in the multi-spectral image to be detected; and the physical features related to the physical properties of the electroplating layer of the electroplated workpiece are extracted in combination with the feature engineering method; the extracted multi-level features of the multi-spectral image to be detected and the physical features of the electroplated workpiece to be detected are fused; the feature dimensionality reduction technology is used to compress and screen the fused features to obtain the fused feature vector of the multi-spectral image to be detected.

[0065] The defect detection model is established using a support vector machine (SVM), and the defect detection model is trained using the fused feature vector of the multispectral sample image and the preset common defect category labels of the electroplated workpiece finished product to learn the mapping relationship between the fused features of the multispectral sample image and the preset common defect categories of the electroplated workpiece finished product; thereby determining whether the sample image has defects and the categories of the defects that exist.

[0066] The trained defect detection model is used to detect the appearance defects of the finished electroplated workpiece in the image to be detected. According to the mapping relationship between the fusion features of the multispectral sample image learned by the defect detection model and the preset common defect categories of the finished electroplated workpiece, it is judged whether the fusion feature vector of the multispectral image to be detected satisfies the mapping relationship. If not, the defect detection model outputs the detection result that there are no appearance defects in the layer of the image to be detected. If so, the defect detection model outputs the detection result that there are appearance defects in the image to be detected and the defect categories. The embodiment of the present application realizes high-accuracy, high-precision and high-efficiency detection of appearance defects in the electroplated layer of the finished electroplated workpiece.

[0067] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An electroplating process, characterized in that: include: Using ultrasonic cold stripping and ultrasonic chemical degreasing to remove the attached matter on the surface of the first workpiece to be electroplated, to obtain a second workpiece to be electroplated; Activating the second workpiece to be electroplated with dilute acid to remove residual oxide layers and minor defects on the surface of the second workpiece to be electroplated, thereby obtaining a third workpiece to be electroplated; The third workpiece to be electroplated is placed uniformly and quickly in an electroplating tank by using a centrifugal loading device; wherein an appropriate amount of electroplating nickel liquid mixed with accompanying plating steel beads is added to the electroplating tank; a power source is turned on to perform centrifugal nickel electroplating treatment, so that a uniform nickel plating layer is formed on the surface of the third workpiece to be electroplated; after the electroplating is completed, the workpiece is quickly taken out of the electroplating tank by using a centrifugal discharging device to obtain a first workpiece to be gold-plated; Placing the first workpiece to be gold-plated in a gold plating solution, and performing a centrifugal pre-gold plating process to obtain a second workpiece to be gold-plated, thereby improving the bonding strength between the gold-plated layer and the nickel-plated layer; placing the second workpiece to be gold-plated in a gold plating solution again, and performing a centrifugal pre-gold plating process to form a gold-plated layer on the surface of the second workpiece to be gold-plated, thereby obtaining a first gold-plated workpiece; Placing the first gold-plated workpiece in a centrifugal drying device to perform a centrifugal drying process to remove the electroplating liquid on the surface of the first gold-plated workpiece to obtain a second gold-plated workpiece; The second gold-plated workpiece is placed in a drying device for drying to ensure that the coating on the surface of the second gold-plated workpiece is completely dried and solidified to obtain a finished electroplated workpiece. The finished electroplated workpiece after drying is subjected to quality inspection to ensure that the coating quality meets the requirements.

2. The electroplating process according to claim 1, characterized in that: The method of removing the attached matter on the surface of the first workpiece to be electroplated by ultrasonic cold stripping and ultrasonic chemical degreasing to obtain the second workpiece to be electroplated includes: Placing the first workpiece to be electroplated in an ultrasonic cleaning machine, using ultrasonic vibration to rapidly remove the attachments on the surface of the first workpiece to be electroplated in a low temperature environment, thereby providing a clean workpiece surface for subsequent processes, and obtaining a fourth workpiece to be electroplated; The fourth workpiece to be electroplated is placed in an ultrasonic cleaning solution containing a degreasing agent, and the ultrasonic vibration and cavitation effect are used to accelerate the decomposition and removal of oil stains on the surface of the fourth electroplated workpiece by the degreasing agent, thereby further improving the cleanliness of the workpiece surface and obtaining a second workpiece to be electroplated.

3. The electroplating process according to claim 1, characterized in that: The second workpiece to be electroplated is activated by using a dilute acid to remove the residual oxide layer and minor defects on the surface of the second workpiece to be electroplated to obtain a third workpiece to be electroplated, comprising: The oxides and rust on the surface of the second workpiece to be electroplated are dissolved by an acidic solution to expose a clean metal surface, thereby obtaining a fifth workpiece to be electroplated; the fifth workpiece to be electroplated is passivated to form a stable oxide protective layer on the surface of the substrate, thereby obtaining a sixth workpiece to be electroplated; the substrate of the sixth workpiece to be electroplated is activated by using a dilute acid at an activation temperature of 25°C to 35°C to remove the residual oxides and tiny contaminants on the surface of the sixth workpiece to be electroplated, thereby ensuring that the surface of the substrate of the sixth workpiece to be electroplated is completely clean and active, thereby obtaining a third workpiece to be electroplated.

4. The electroplating process according to claim 3, characterized in that: The dilute acid is a sulfuric acid solution with a mass fraction of 9.5% to 10.5% or a hydrochloric acid solution with a mass fraction of 9.5% to 10.5%.

5. The electroplating process according to claim 1, characterized in that: The pH value of the nickel electroplating solution is 9.5-11.

1.

6. The electroplating process according to claim 1, characterized in that: The temperature of the centrifugal gold plating treatment is 55-65° C., the current is 1.5-5A, and the duration is 55-65 minutes.

7. The electroplating process according to any one of claims 1 to 6, characterized in that: The finished electroplated workpiece is subjected to quality inspection, including: Using a line scan camera to collect images to be inspected at various angles and orientations of the electroplated workpiece product; The salt and pepper noise and Gaussian noise in the image to be detected are removed by a pre-built and trained deep convolutional neural network denoising model to obtain a first image; wherein the areas where the salt and pepper noise and Gaussian noise exist in the collected sample image are marked, and the deep convolutional neural network denoising model is trained using the marked sample image, and the deep convolutional neural network denoising model outputs an image with the salt and pepper noise and Gaussian noise removed; Performing illumination intensity optimization correction processing on the first image by using an illumination correction algorithm to obtain a second image; The texture, shape and color features in the image to be detected are extracted by a pre-built and trained deep convolutional neural network feature extraction model; the texture, shape and color features are mapped into texture feature vectors, shape feature vectors and color feature vectors; the principal component analysis method and the mutual information feature screening method are used to screen out the target texture feature vector, target shape feature vector and target color feature vector that meet the preset defect characteristics; The target texture feature vector, the target shape feature vector and the target color feature vector are input into a pre-built and trained support vector quality detection model to detect whether the electroplated workpiece has quality defects; the defective electroplated workpieces with quality defects and the qualified electroplated workpieces without quality defects are automatically classified through a screening device.

8. The electroplating process according to claim 7, characterized in that: Performing illumination intensity optimization correction processing on the first image by using an illumination correction algorithm to obtain a second image includes: Calculating the illumination intensity correction value of the pixel points in the first image using the illumination intensity calculation formula, and using the illumination intensity correction value as the actual illumination intensity value of the pixel points in the first image, thereby completing the illumination intensity optimization correction processing of all the pixel points in the first image, and obtaining the second image; The calculation formula of light intensity is as follows: ； in, Represents the ambient light constant; represents the diffusion coefficient; represents a pixel value of a pixel in the first image; represents the distance decay function, , and denote the coefficients for adjusting row and column influences, respectively. Represents the distance between the pixel and the light source. represents the row position of the pixel in the first image, represents the column position of the pixel in the first image; Represents the directional coefficient, which is used to adjust the contribution weight of directional light to light intensity; represents the directional light function, and Represents the angle between the light source direction and the normal direction of the pixel surface; represents the specular reflection coefficient; represents the specular reflection function, Indicates the roughness of a pixel.

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