Method for processing outer-layer circuit of micro-spacing circuit board

Abstract

The invention belongs to the technical field of circuit board manufacturing, and provides a micro-pitch circuit board outer circuit processing method, which comprises the following steps: acquiring a first coating parameter for constructing an ink pattern and a first baking and curing parameter of baking and curing equipment, and acquiring a first chromatic aberration parameter of a circuit board after fine carving based on circuit board image data calculation; then processing the first coating parameter, the first baking and curing parameter and the first color difference parameter to obtain a first exterior line processing feature, and constructing a bonding pad windowing color difference uniformity control model according to the first exterior line processing feature and a set first windowing burning and carving method; processing second external line processing characteristics obtained by processing the characteristics of the circuit board to be processed to obtain a second windowing and burning method, controlling the working parameters of related equipment in a high-precision manner according to the second windowing and burning method, and performing feedback adjustment on the model by using the color difference callback model, so that the processing attractiveness of the circuit board is improved, the welding defective rate of the circuit board is reduced, and the production efficiency of the circuit board is improved. Therefore, the circuit board processing and production quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board manufacturing, and in particular to a method for processing outer layer circuits of a micro-pitch circuit board. Background Art

[0002] As COB mini LED and MacroLED technologies develop towards higher precision and better performance, the demand for circuit boards with pad spacing below P1.5mm is growing. However, in the production process of such circuit boards, there is a difficult problem. Because the size of the solder mask opening is in the extremely fine range of 10um x 10um to 50x 50um, traditional DI solder mask imaging equipment has serious limitations when performing graphic exposure on commonly used solder mask inks such as black oil or white oil. On the one hand, due to the combined influence of the equipment's optical system, light source stability and the characteristics of the ink itself, obvious color differences are easily produced during the exposure process, resulting in differences in the color presentation of pad openings in different areas, which cannot meet the strict requirements of the product for appearance color consistency; on the other hand, when exposing large-area circuit boards, graphic splicing is often required to cover the entire board surface, and DI equipment is very prone to splicing shadows in this process, further destroying the uniformity of the board color, which not only affects the appearance of the product, but may also mislead the subsequent electronic component welding process, resulting in frequent defects such as cold soldering and wrong soldering, which greatly reduces the product yield and seriously hinders the high-quality development of the industry.

[0003] Therefore, the prior art has the following problems:

[0004] The first is how to reduce the above-mentioned color difference problem, how to use the data related to the whole process of circuit board production to automatically generate the original burning method, and how to use the image-related parameters of the produced burned circuit board, especially the parameters related to the appearance uniformity and aesthetics of the circuit board product to improve the circuit board yield. How to control the equipment to improve the window opening burning method, and use the precise window opening burning method to control the color difference uniformity of the pad window, so that it can accurately burn the pad window with a size within certain production requirements on the ink layer, thereby fundamentally making up for the shortcomings of traditional DI equipment in the color difference processing of tiny pad window, greatly improving the product yield, and injecting strong impetus for COB LED circuit boards to move towards higher quality and more refined production. Summary of the invention

[0005] The object of the present invention is to overcome the defects of the prior art. The present invention specifically proposes a brand-new and breakthrough manufacturing process, aiming to completely overcome the above-mentioned color difference problem. The core innovation lies in abandoning the inherent mode of the traditional DI solder mask imaging equipment in the window processing of micro-sizes, and boldly introducing a high-precision laser equipment to deeply participate in the circuit board graphic optimization process. First, according to the standard process flow, black oil or white oil is evenly coated on the surface of the circuit board, and the DI solder mask imaging equipment is used to perform a full-board primary exposure on the ink layer. The purpose of this step is to quickly construct a basic ink graphic framework. Although it is known that there are color difference and splicing shadow problems, it can provide a general graphic position guidance for subsequent precise processing. Immediately afterwards, the circuit board is sent into a high-precision baking and curing equipment, and appropriate parameters such as temperature and time are set according to the curing characteristics of the ink to ensure the stable curing of the ink layer, laying a solid foundation for subsequent laser processing. Subsequently, the laser equipment is started. With its ultra-fine spot, high energy density and excellent controllability, the cured ink layer graphic is finely carved for the second time. By intelligently adjusting key parameters such as laser wavelength, pulse width, and scanning path, it can accurately burn out pad windows with sizes strictly ranging from 10um x 10um to 50x 50um on the ink layer, and ensure that the window colors on the entire board surface are uniform, perfectly meeting the strict requirements of the finished board appearance with basically no color difference. This three-stage innovative process of "primary exposure + curing + laser fine repair" fundamentally makes up for the shortcoming of the traditional DI equipment in the color difference processing of micro-pad windows, greatly improving the product yield rate, and injecting strong impetus for the COB LED circuit board to move towards higher quality and more refined production.

[0006] In the first aspect of the present invention, a method for processing the outer layer circuit of a micro-pitch circuit board is provided, and the method includes the following steps:

[0007] S1. Ink coating preparation: Select black oil or white oil solder mask ink that is suitable for the circuit board and has high color difference stability. Calculate the ink consumption according to the circuit board size and ink characteristics, and use a screen printing device to evenly and smoothly coat the ink on the surface of the circuit board, ensuring that the thickness deviation of the ink layer is controlled within a certain range to obtain an ink-coated circuit board;

[0008] S2. DI primary exposure: Place the ink-coated circuit board on the workbench of a high-precision DI solder mask imaging equipment, and start the equipment for full-board exposure operation according to the set light source intensity and exposure time to obtain an exposed circuit board;

[0009] S3. Baking and curing: Transfer the exposed circuit board into a baking and curing equipment, and ensure the full curing of the ink layer according to the set baking and curing parameters to obtain a baked and cured circuit board;

[0010] S4. Window opening and engraving: Place the baked and cured circuit board on an ultra-precision machining platform, start the engraving program using the window opening and engraving method, adjust the equipment engraving parameters according to the window opening and engraving method to ensure the accuracy of the engraved window size, and obtain a windowed circuit board;

[0011] S5. Color difference callback quality control: Process the windowed circuit board to obtain circuit board image data, calculate color difference parameters based on the circuit board image data, and conduct quality evaluation on the windowed circuit board based on the color difference parameters.

[0012] Further, in step S4, the window opening and engraving method is obtained using a pad window opening color difference uniformity control model.

[0013] Further, the steps of training the pad window opening color difference uniformity control model and obtaining the window opening and engraving method for the circuit board to be processed are as follows:

[0014] Collect the first coating parameters of the ink-coated circuit board and the first baking and curing parameters of the baking and curing equipment, and collect the first color difference parameters calculated based on the circuit board image data of the circuit board after fine carving. Then process the first coating parameters, the first baking and curing parameters, and the first color difference parameters to obtain the first external processing features;

[0015] Obtain the first window opening and engraving method for the circuit board window opening at this time, and construct a pad window opening color difference uniformity control model according to the first external processing features and the set first window opening and engraving method;

[0016] Collect the second coating parameters for constructing the ink pattern of the circuit board to be processed and the second baking and curing parameters of the baking and curing equipment. Then process the second coating parameters, the second baking and curing parameters, and the first color difference parameters to obtain the second external processing features, and input the processed second external processing features into the pad window opening color difference uniformity control model to obtain the second window opening and engraving method for the circuit board to be processed;

[0017] According to the second window opening and engraving method, accurately control the working parameters of the relevant equipment and use the second color difference parameters calculated based on the circuit board image data of the circuit board finely carved using the second window opening and engraving method to callback the model and conduct feedback adjustment on the model.

[0018] Further, the first coating parameters include the first curing temperature, the first curing time, the first curing ambient humidity, and the first ink consumption;

[0019] The second coating parameters include the second curing temperature, the second curing time, the second curing ambient humidity, and the second ink consumption;

[0020] The ink consumption for coating the circuit board is calculated based on the circuit board size and area, coating thickness, ink density, the proportion of solid components in the ink, and the loss ratio during the coating process.

[0021] Further, the first baking and curing parameters include the first baking temperature, the first heating rate, the first holding time, and the first cooling time;

[0022] The second coating parameters include the second baking temperature, the second heating rate, the second holding time, and the second cooling time.

[0023] Further, the first color difference parameter or the second color difference parameter is calculated by combining the overall color difference value based on the color space obtained by direct measurement with the grayscale value of the circuit board image data of the finely carved circuit board. The first color difference parameter or the second color difference parameter is calculated through their respective corresponding parameters.

[0024] Further, the process of obtaining the first outer line processing feature by processing the first coating parameters, the first baking and curing parameters, and the first color difference parameter is to perform feature processing by means of feature vector splicing of the first coating parameters, the first baking and curing parameters, and the first color difference parameter;

[0025] The process of obtaining the second outer line processing feature by processing the second coating parameters, the second baking and curing parameters, and the first color difference parameter is to perform feature processing by means of feature vector splicing of the second coating parameters, the second baking and curing parameters, and the first color difference parameter.

[0026] Further, the micro-pitch circuit board processing method generation model adopts a fisher criterion classification model improved based on high-resolution image data.

[0027] Further, the solder pad opening color difference uniformity control model adopts a support vector machine model based on color difference parameter feedback and callback.

[0028] There is also provided a micro-pitch circuit board outer layer line processing system for implementing a micro-pitch circuit board outer layer line processing method, including an ink coating module, a DI primary exposure module, a baking and curing module, a window engraving module, and a color difference callback quality control module:

[0029] The ink coating module: is used to select black or white solder resist ink that is suitable for the circuit board and has high color difference stability, calculate the ink consumption according to the circuit board size and ink characteristics, and use screen printing equipment to evenly and smoothly coat the ink on the surface of the circuit board, ensuring that the thickness deviation of the ink layer is controlled within a certain range to obtain an ink-coated circuit board;

[0030] The D I primary exposure module: Linked to the ink coating module, it is used to place the ink-coated circuit board on the workbench of a high-precision D I solder mask imaging device, and start the device for full-board exposure operation according to the set light source intensity and exposure time to obtain an exposed circuit board;

[0031] The baking and curing module: Linked to the D I primary exposure module, it is used to transfer the exposed circuit board into a baking and curing device, and ensure the full curing of the ink layer according to the set baking and curing parameters to obtain a baked and cured circuit board;

[0032] The window opening engraving module: Linked to the baking and curing module, it is used to place the baked and cured circuit board on an ultra-precision machining platform, start the engraving program using the window opening engraving method, and adjust the device engraving parameters according to the window opening engraving method to ensure the accuracy of the engraved window size and obtain a windowed circuit board;

[0033] The color difference callback quality control module: Linked to the window opening engraving module, the ink coating module, and the baking and curing module, it is used to process the windowed circuit board to obtain circuit board image data, calculate color difference parameters based on the circuit board image data, and conduct quality evaluation on the windowed circuit board based on the color difference parameters.

[0034] Through the above innovative invention process, the present invention reduces the color difference of the circuit board finished product, automatically generates an engraving method using the relevant data of the entire circuit board production process, and uses the image-related parameters of the engraved circuit board, especially the color difference parameters related to the appearance uniformity and aesthetics of the circuit board product and the types of ink coatings, to improve the yield rate of the circuit board. By using a precise window opening engraving method to control the color difference uniformity of the pad window opening, it can accurately engrave pad window openings with sizes meeting certain production requirements on the ink layer, thus fundamentally making up for the shortcoming of traditional D I devices in dealing with the color difference of small pad window openings, greatly improving the yield rate of the product, and injecting strong impetus for the COB LED circuit board to move towards higher quality and more refined production. In actual large-scale production applications, after random sampling and testing statistics by a third-party testing agency and customers in multiple batches, compared with the traditional process, the yield rate of the product's appearance color difference index has increased by 40%, winning a significant advantage for the COB LED circuit board industry in the high-end market competition.

[0035] More embodiments and improvement effects of the present invention will be further introduced in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic flow chart of the processing technology method of the present invention;

[0037] Figure 2Schematic diagram of the model in step S4 of the method for processing the outer layer circuit of the micro-pitch circuit board of the present invention;

[0038] Figure 3 Schematic diagram of the processing principle of the laser device;

[0039] Figure 4 Curing curve graph of the ink;

[0040] Figure 5 Schematic diagram of the support vector machine model based on color difference parameter feedback callback in the present invention;

[0041] Figure 6 Schematic diagram of the structure of the electronic device according to the embodiment of the present invention. Detailed implementation manners

[0042] Next, with reference to the accompanying drawings and specific implementation manners, the invention will be further described.

[0043] In the embodiment of the present invention, a method for processing the outer layer circuit of a micro-pitch circuit board is provided, and the method includes the following steps:

[0044] S1. Ink coating preparation: Select black or white solder resist ink that is suitable for the circuit board and has high color difference stability. Calculate the ink consumption according to the circuit board size and ink characteristics. Use a screen printing device to evenly and flatly coat the ink on the surface of the circuit board, and ensure that the thickness deviation of the ink layer is controlled within a certain range to obtain an ink-coated circuit board;

[0045] S2. DI primary exposure: Place the ink-coated circuit board on the workbench of a high-precision DI solder resist imaging device, and start the full-board exposure operation according to the set light source intensity and exposure time to obtain an exposed circuit board;

[0046] S3. Baking and curing: Transfer the exposed circuit board to a baking and curing device, and ensure that the ink layer is fully cured according to the set baking and curing parameters to obtain a baked and cured circuit board;

[0047] S4. Window opening engraving: Place the baked and cured circuit board on an ultra-precision processing platform, start the engraving program using the window opening engraving method, and adjust the device engraving parameters according to the window opening engraving method to ensure that the engraved window size is accurate to obtain a window-opened circuit board;

[0048] S5. Color difference callback quality control: Obtain circuit board image data according to the window-opened circuit board, calculate color difference parameters based on the circuit board image data, and evaluate the quality of the window-opened circuit board based on the color difference parameters.

[0049] In this embodiment, the specific steps are as follows:

[0050] 1. Ink Coating Preparation: Select black or white solder mask ink that is compatible with COB LED circuit boards and has high color difference stability. According to the circuit board size and ink characteristics, accurately calculate the ink consumption. Use screen printing equipment to evenly and smoothly coat the ink on the surface of the circuit board that has undergone strict pretreatment, ensuring that the thickness deviation of the ink layer is controlled within a very small range to avoid subsequent color difference problems caused by uneven thickness.

[0051] 2. DI Initial Exposure: Place the circuit board coated with ink on the workbench of a high-precision DI solder mask imaging device. According to the preset full-board graphic data, start the device for full-board exposure operation. During this process, monitor the device operation parameters in real time, such as light source intensity, exposure time, etc. Since it is full-board exposure, color difference and splicing shadows can be completely avoided, but efforts should be made to ensure the integrity and relative position accuracy of the graphics to provide a reliable initial reference for subsequent laser processing.

[0052] 3. Baking and Curing: Transfer the circuit board after the initial exposure to a professional baking and curing device. According to the curing curve of the selected ink, finely set parameters such as baking temperature, heating rate, holding time, and cooling method. For example, for a specific type of white oil, set the initial heating rate to 5°C / min, heat up to 120°C and hold for 30 min, and then naturally cool to room temperature to ensure that the ink layer is fully cured, enhancing its mechanical strength and chemical stability to withstand subsequent laser processing impacts.

[0053] In this embodiment, the window engraving of the present invention uses laser engraving, and the quality control of color difference callback can also be referred to as the quality control of subsequent circuit board production processes.

[0054] 4. Laser Fine Repair Alignment and Processing: Place the cured circuit board on an ultra-precision processing platform. Use a high-resolution vision recognition system to capture the copper foil graphic reference marks on the circuit board. Combine with a multi-axis precision motion control system to achieve high-precision alignment between the processing focus of the laser device and the area to be finely repaired on the ink layer, with the error controlled at the sub-micron level. According to the laser parameter combination optimized through a large number of experiments in advance, start the laser engraving program. Dynamically adjust the laser pulse energy and scanning speed according to the window opening requirements of different sizes of pads to ensure that the engraved window size accurately falls within the range of 10um x 10um to 50x 50um, and the color is uniform without obvious color difference. During the processing, use an online inspection AOI system to monitor the window quality in real time. Once an abnormality is found, immediately pause and adjust the parameters.

[0055] 5. Subsequent quality control: After laser processing, use professional color difference detection instruments, microscopes, AOI and other equipment to conduct a comprehensive quality inspection of the circuit board. Focus on checking key indicators such as the dimensional accuracy of the pad opening, color difference uniformity, and the adhesion between the ink layer and the circuit board substrate. For qualified products, perform subsequent electrical performance tests, assembly and other processes according to the conventional process flow to finally obtain high-quality COB mini LED and Macro LED circuit board products without color difference in appearance.

[0056] Further, in step S4, the pad opening engraving method is obtained by using a color difference uniformity control model for pad opening.

[0057] Further, the steps of training the color difference uniformity control model for pad opening and obtaining the pad opening engraving method for the circuit board to be processed are as follows:

[0058] Collect the first coating parameters of the ink-coated circuit board and the first baking and curing parameters of the baking and curing equipment, and collect the first color difference parameter calculated based on the circuit board image data after fine carving. Then process the first coating parameter, the first baking and curing parameter, and the first color difference parameter to obtain the first external processing feature;

[0059] Obtain the first pad opening engraving method for the circuit board window at this time, and construct a color difference uniformity control model for pad opening according to the first external processing feature and the set first pad opening engraving method;

[0060] Collect the second coating parameters for constructing the ink pattern of the circuit board to be processed and the second baking and curing parameters of the baking and curing equipment. Then process the second coating parameter, the second baking and curing parameter, and the first color difference parameter to obtain the second external processing feature, and input the processed second external processing feature into the color difference uniformity control model for pad opening to obtain the second pad opening engraving method for the circuit board to be processed;

[0061] According to the second pad opening engraving method, accurately control the working parameters of relevant equipment and use the second color difference parameter calculated based on the circuit board image data finely carved by the second pad opening engraving method to callback the model and perform feedback adjustment on the model.

[0062] Further, the first coating parameter includes the first curing temperature, the first curing time, the first curing environment humidity, and the first ink consumption;

[0063] The second coating parameter includes the second curing temperature, the second curing time, the second curing environment humidity, and the second ink consumption;

[0064] Among them, the ink consumption for coating the circuit board is calculated from the circuit board size area, coating thickness, ink density, the proportion of solid components in the ink, and the loss proportion during the coating process. The calculation formula is as follows:

[0065]

[0066] In the formula, P(i) is the ink consumption, S is the circuit board area, D is the coating thickness, ρ is the ink density, S h is the proportion of solid components in the ink, and θ is the loss proportion during the coating process.

[0067] Furthermore, the first baking and curing parameters include the first baking temperature, the first heating rate, the first holding time, and the first cooling time;

[0068] The second coating parameters include the second baking temperature, the second heating rate, the second holding time, and the second cooling time.

[0069] In this embodiment, since the gray values represented by different colors are different in the image data, the gray value data pair is used to correspondingly correct the color difference data, making the color difference correction model more accurate, and the calculation is more concise than other methods.

[0070] Furthermore, the first color difference parameter or the second color difference parameter is calculated by combining the overall color difference value based on the color space obtained by direct measurement with the gray value of the circuit board image data of the finely carved circuit board. The first color difference parameter or the second color difference parameter is calculated through their respective corresponding parameters:

[0071]

[0072] In the formula, ΔE δ is the color difference parameter, g bw represents the gray value of the black and white regions in the circuit board image data, g rg represents the gray value of the red and green regions in the circuit board image data, g yb represents the gray value of the yellow and blue regions in the circuit board image data, and g represents the overall gray value of the circuit board image data.

[0073] Furthermore, the first outer processing feature obtained by processing the first coating parameter, the first baking and curing parameter, and the first color difference parameter is obtained by performing feature vector splicing on the first coating parameter, the first baking and curing parameter, and the first color difference parameter for feature processing;

[0074] Processing the second coating parameter, the second baking and curing parameter, and the first color difference parameter to obtain a second outer line processing feature is performed by concatenating the feature vectors of the second coating parameter, the second baking and curing parameter, and the first color difference parameter for feature processing.

[0075] Further, the model generation method for the micro-pitch circuit board processing adopts a fisher criterion classification model improved based on high-resolution image data.

[0076] Further, the solder pad opening color difference uniformity control model adopts a support vector machine model based on color difference parameter feedback callback, and the calculation formula is as follows:

[0077]

[0078] Where ω and b are the normal vector and intercept of the hyperplane respectively, obtained by training using the first outer line processing feature and the first opening engraving method. S(X) is the output first opening engraving method or second opening engraving method. When the second color difference parameter has not been generated, the value of ΔE δ is 0. After the model starts to generate the second color difference parameter, ΔE δ is the second color difference parameter. [k] represents the ink type coefficient. The black solder mask ink represents that the ink type coefficient is 1, and the black solder mask ink represents that the ink type coefficient is -1.

[0079] As Figure 5 shown, compared with the setting of the general support vector machine, the difference of the support vector machine in the present invention is that according to the input features, a more accurate window engraving method can be obtained through processing the input features.

[0080] In this embodiment, the opening engraving method is obtained by the value of S(X). When the value of S(X) is less than -1, the laser pulse energy value and the scanning speed are set according to different opening requirements. At this time, if the opening requirement size is 20um x 20um, the laser pulse energy value is set to 0.1 - 1mJ, not including 1mJ, and the scanning speed is 500mm / S - 700mm / S, not including 700mm / S. When S(X) is greater than or equal to -1 and less than 0, at this time, if the opening requirement size is 20um x 20um, the laser pulse energy value is set to 1 - 3mJ, and the scanning speed is 700mm / S - 1000mm / S. If it is equal to 0 and less than or equal to 1 and if it is greater than 1, the relevant settings are made according to the needs of those skilled in the art accordingly, which will not be elaborated here.

[0081] Also disclosed is a micro-pitch circuit board outer layer circuit processing system for implementing a micro-pitch circuit board outer layer circuit processing method, including an ink coating module, a DI primary exposure module, a baking and curing module, a window engraving module, and a color difference callback quality control module:

[0082] The ink coating module: is used to select black or white solder resist ink that is suitable for the circuit board and has high color difference stability, calculate the ink consumption according to the circuit board size and ink characteristics, and use screen printing equipment to evenly and flatly coat the ink on the surface of the circuit board, ensuring that the thickness deviation of the ink layer is controlled within a certain range to obtain an ink-coated circuit board;

[0083] The DI primary exposure module: is linked to the ink coating module and is used to place the ink-coated circuit board on the workbench of a high-precision DI solder resist imaging device, and start the full-board exposure operation of the device according to the set light source intensity and exposure time to obtain an exposed circuit board;

[0084] The baking and curing module: is linked to the DI primary exposure module and is used to transfer the exposed circuit board into a baking and curing device, and ensure that the ink layer is fully cured according to the set baking and curing parameters to obtain a baked and cured circuit board;

[0085] The window engraving module: is linked to the baking and curing module and is used to place the baked and cured circuit board on an ultra-precision processing platform, start the engraving program using the window engraving method, and adjust the device engraving parameters according to the window engraving method to ensure that the engraved window size is accurate to obtain a windowed circuit board;

[0086] The color difference callback quality control module: is linked to the window engraving module, the ink coating module, and the baking and curing module, and is used to process the windowed circuit board to obtain circuit board image data, calculate color difference parameters based on the circuit board image data, and perform quality evaluation on the windowed circuit board based on the color difference parameters.

[0087] Through the above innovative invention process, the present invention reduces the color difference of the finished circuit board, and uses the relevant data of the entire production process of the circuit board to automatically generate an innovative engraving method. The relevant parameters of the image of the engraved circuit board are used, especially the color difference parameters related to the appearance uniformity and aesthetics of the circuit board product and the types of ink coating, to improve the yield rate of the circuit board. The color difference uniformity of the pad opening is controlled by a precise window opening engraving method, so that it can accurately engrave a pad opening with a size meeting certain production requirements on the ink layer, thereby fundamentally making up for the shortcoming of the traditional DI equipment in dealing with the color difference of the micro-pad opening, greatly improving the product yield rate, and injecting strong impetus into the COB LED circuit board towards higher quality and more refined production. In the actual large-scale production application, through the random sampling and testing statistics of multiple batches by a third-party testing agency and customers, compared with the traditional process, the yield rate of the appearance color difference index of the product has increased by 40%, winning a significant advantage for the COB LED circuit board industry in the high-end market competition.

[0088] For the part of the module structure not specifically defined in the present invention, the content recorded in the prior art shall prevail. The prior art mentioned in the foregoing background art part and the specific embodiment part of the present invention can be used as a part of the present invention to understand the meaning of some technical features or parameters.

Claims

1. A method for processing outer layer circuits of a fine pitch circuit board, characterized in that: The method comprises the following steps: S1. Ink coating preparation: Select black or white solder resist ink that is suitable for the circuit board and has high color difference stability, calculate the ink dosage according to the size of the circuit board and the ink characteristics, use screen printing equipment to evenly and evenly apply the ink on the surface of the circuit board, and ensure that the thickness deviation of the ink layer is controlled within a certain range to obtain an ink-coated circuit board; S2, DI initial exposure: placing the ink-coated circuit board on a workbench of a high-precision DI solder resist imaging device, starting the device to perform full-board exposure operation according to the set light source intensity and exposure time to obtain an exposed circuit board; S3, baking and curing: transferring the exposed circuit board to a baking and curing device, and ensuring that the ink layer is fully cured according to the set baking and curing parameters to obtain a baking and curing circuit board; S4, window burning: placing the baked and cured circuit board on an ultra-precision processing platform, starting the burning program using the window burning method, adjusting the burning parameters of the equipment according to the window burning method to ensure that the size of the burned window is accurate, and obtaining the window circuit board; S5, color difference callback quality control: circuit board image data is obtained according to the windowed circuit board processing, color difference parameters are calculated based on the circuit board image data, and quality evaluation of the windowed circuit board is performed based on the color difference parameters.

2. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 1, characterized in that: In step S4, the windowing method is obtained by using a pad windowing color difference uniformity control model.

3. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 2, characterized in that: The steps of training the pad window color difference uniformity control model and obtaining the window burning method of the circuit board to be processed are as follows: Collecting a first coating parameter of the ink-coated circuit board and a first baking and curing parameter of the baking and curing equipment, and collecting a first color difference parameter of the circuit board after fine carving calculated based on the circuit board image data, and then processing the first coating parameter, the first baking and curing parameter and the first color difference parameter to obtain a first external line processing feature; Obtaining a first windowing method for windowing the circuit board at this time, and constructing a pad windowing color difference uniformity control model according to the first external line processing feature and the set first windowing method; Collecting the second coating parameter of the ink pattern constructed on the circuit board to be processed and the second baking and curing parameter of the baking and curing equipment, then processing the second coating parameter, the second baking and curing parameter and the first color difference parameter to obtain the second external line processing feature, and inputting the processed second external line processing feature into the pad window color difference uniformity control model to obtain the second window burning method for the circuit board to be processed; According to the second windowing method, the working parameters of the relevant equipment are controlled with high precision, and the second color difference parameter callback model is calculated based on the circuit board image data finely carved by the second windowing method to feedback adjust the model.

4. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 3, characterized in that: The first coating parameters include a first curing temperature, a first curing time, a first curing environment humidity, and a first ink dosage; The second coating parameters include a second curing temperature, a second curing time, a second curing environment humidity and a second ink dosage; The amount of ink used to coat the circuit board is calculated based on the size and area of ​​the circuit board, the coating thickness, the ink density, the proportion of solid components in the ink, and the loss ratio during the coating process.

5. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 3, characterized in that: The first baking and curing parameters include a first baking temperature, a first heating rate, a first heat preservation time and a first cooling time; The second coating parameters include a second baking temperature, a second heating rate, a second heat preservation time and a second cooling time.

6. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 3, characterized in that: The first color difference parameter or the second color difference parameter is calculated by combining the overall color difference value based on the color space obtained by direct measurement with the grayscale value of the circuit board image data of the circuit board after fine carving. The first color difference parameter or the second color difference parameter is calculated by their respective corresponding parameters.

7. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 4, 5 or 6, characterized in that: The first coating parameter, the first baking and curing parameter and the first color difference parameter are processed to obtain the first external line processing feature by performing feature processing on the first coating parameter, the first baking and curing parameter and the first color difference parameter by a method of splicing feature vectors; The second coating parameter, the second baking and curing parameter and the first color difference parameter are processed to obtain the second external line processing feature by performing feature processing on the second coating parameter, the second baking and curing parameter and the first color difference parameter by means of feature vector splicing.

8. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 7, characterized in that: The micro-pitch circuit board processing method generation model adopts a Fisher criterion classification model improved based on high-resolution image data.

9. A method for processing outer layer circuits of a fine pitch circuit board as claimed in claim 6, characterized in that: The pad window color difference uniformity control model adopts a support vector machine model based on color difference parameter feedback callback.

10. A system for processing outer layer circuits of a micro-pitch circuit board as claimed in claim 1, comprising an ink coating module, a DI initial exposure module, a baking and curing module, a window opening and burning module and a color difference callback quality control module, characterized in that: The ink coating module is used to select black or white solder resist ink that is suitable for the circuit board and has high color difference stability, calculate the ink dosage according to the size of the circuit board and the ink characteristics, and use screen printing equipment to evenly and evenly coat the ink on the surface of the circuit board to ensure that the thickness deviation of the ink layer is controlled within a certain range, so as to obtain an ink-coated circuit board; The DI initial exposure module is linked to the ink coating module and is used to place the ink coated circuit board on the workbench of the high-precision DI solder resist imaging device, and start the device to perform full-board exposure operation according to the set light source intensity and exposure time to obtain an exposed circuit board; The baking and curing module is linked to the DI primary exposure module and is used to transfer the exposed circuit board to the baking and curing equipment, and ensure that the ink layer is fully cured according to the set baking and curing parameters to obtain a baking and curing circuit board; The windowing and burning module is linked to the baking and curing module, and is used to place the baking and curing circuit board on the ultra-precision processing platform, start the burning program using the windowing and burning method, and adjust the burning parameters of the equipment according to the windowing and burning method to ensure that the size of the burned window is accurate, so as to obtain the windowing circuit board; The color difference callback quality control module is linked to the window burning module, the ink coating module and the baking and curing module, and is used to obtain circuit board image data according to the window circuit board processing, calculate color difference parameters based on the circuit board image data, and evaluate the quality of the window circuit board based on the color difference parameters.

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