Manufacturing method and system of light emitting diode ink color tube control circuit board and circuit board

Abstract

This application provides a method, system, and circuit board for manufacturing a light-emitting diode (LED) ink color control circuit board. The method includes: completing the fabrication and tension control of a multi-directional stretching screen; after standardized ink mixing, sequentially printing solder resist on both sides of the substrate and controlling the wet film thickness; and then completing zoned exposure development and thermal ultraviolet curing. This method achieves high-precision consistency control of solder resist ink color, improves the ink color uniformity of products in the same batch, reduces the incidence of defects such as color difference, and improves the performance reliability and batch production stability of the circuit board.

Description

Technical Field

[0001] This application relates to the field of circuit board manufacturing, and in particular to a method, system and circuit board for manufacturing a light-emitting diode ink color control circuit board. Background Technology

[0002] With the rapid development of the electronics and information industry, light-emitting diodes (LEDs) have been widely used in various optoelectronic displays, general lighting, automotive electronics, and smart terminal devices. Their performance and reliability are highly dependent on the manufacturing precision and quality stability of the supporting circuit boards. Throughout the entire circuit board manufacturing process, the processing quality and color consistency of the solder resist layer are crucial factors determining the product's appearance, electrical protection performance, environmental weather resistance, and optical output stability. They are also key nodes for quality control in large-scale production.

[0003] In existing technologies, the conventional manufacturing process for LED circuit boards includes core steps such as substrate cutting, inner layer circuit fabrication, lamination, drilling, outer layer electroplating, circuit etching, solder resist printing, text processing, and curing. Regarding ink color control in the solder resist stage, existing conventional processes use a universal screen printing method to prepare the screen, mix the ink using standard stirring, and then perform double-sided printing using universal screen printing parameters. After pre-baking, exposure, and development, curing is completed. The associated electroplating and circuit etching processes mostly employ standardized production lines.

[0004] Existing technologies cannot achieve closed-loop consistency control of solder resist ink color throughout the entire process for LED circuit boards. This easily leads to defects such as uneven ink color, color difference, bubbles, and pinholes in large-scale batch production, resulting in decreased optical performance, insufficient protection performance, and shortened service life of the products. Consequently, these technologies cannot meet the high consistency and high reliability manufacturing requirements of high-end LED products. Summary of the Invention

[0005] This application provides a method, system, and circuit board for manufacturing a light-emitting diode (LED) ink color control circuit board, which can improve the ink color consistency of the same batch of circuit board products and reduce color difference defects.

[0006] In a first aspect, embodiments of this application provide a method for manufacturing a light-emitting diode (LED) ink color control circuit board, comprising:

[0007] The mesh is stretched multiple times in multiple directions. After stretching, the mesh is glued to the frame to obtain the screen. Tension is detected at multiple points on the screen to control the tension of the screen within a preset tension range.

[0008] Take a preset ink and add boiling water according to a preset ratio. After mechanically stirring and mixing, filter and let stand to obtain solder resist ink. Control the viscosity of the solder resist ink within a preset viscosity range.

[0009] An ultra-roughening process is used to perform pre-solder resist treatment on the etched substrate. After the pre-solder resist treatment is completed, solder resist screen printing is performed on the non-LED bead side and the LED bead side of the substrate within a preset time period using the screen and preset squeegee parameters. When performing the solder resist screen printing on the LED bead side, a bed of nails is set up under the substrate and multiple pins are arranged. After the solder resist screen printing, the thickness of the wet film ink layer is controlled within a preset thickness range and the thickness difference is not greater than a preset difference value.

[0010] The substrate after solder resist silkscreen printing is pre-baked, exposed and developed in sequence. The exposure is performed using a laser direct imaging machine, and different preset exposure scales are used for the lamp bead side and the non-lamp bead side.

[0011] The developed substrate is cured with a thermal light source UV curing machine, and the curing speed and curing energy of the thermal light source UV curing machine are controlled within a preset range.

[0012] In one possible implementation, the multi-directional and multiple stretching of the mesh includes step-by-step stretching operations along the X-axis and Y-axis, with a preset resting time after each single stretch; the solder resist silkscreen is applied sequentially, first to the non-LED bead surface and then to the LED bead surface.

[0013] In one possible implementation, the stretching in the X-axis direction is performed 3 times, with each stretch being a first preset stretch; the stretching in the Y-axis direction is performed 2 times, with each stretch being a second preset stretch; and the preset resting time after each stretch is 5 minutes.

[0014] In one possible implementation, after the mechanical stirring and mixing, the mixture is filtered using at least one stage of filter screen, and the speed of the mechanical stirring is controlled within a preset speed range.

[0015] In one possible implementation, the operating speed of the ultra-roughening process is controlled within a preset speed range, and the operation time after the anti-welding pretreatment is completed is controlled not to exceed a preset time threshold.

[0016] In one possible implementation, the pre-baking is performed using a vertical oven, the vacuum level is controlled within a preset vacuum level range during the exposure process, and the side etching amount is controlled not to exceed a preset side etching threshold during the development process.

[0017] In one possible implementation, the pre-baking temperature is controlled at 75°C and the duration is 50 min; the curing speed of the thermal light source UV curing machine is controlled at 2 m / min and the curing energy is 3000 mJ / cm²; the vacuum degree during the exposure process is controlled at 300 mmHg to 370 mmHg; and the lateral etching amount during the development process is controlled at no more than 25 μm.

[0018] In one possible implementation, the preset ink is a photosensitive ink; the preset squeegee parameters include a squeegee hardness of 70°, a squeegee angle of 60°, and a printing pressure of 4 kg / cm²; when multiple ejector pins are deployed, the number of ejector pins is controlled to be within the range of 100 to 300.

[0019] Secondly, embodiments of this application provide a manufacturing system for a light-emitting diode ink color control circuit board. The manufacturing system is used to implement the first aspect and / or various possible implementations of the first aspect, including: an electroplating module, a circuit processing module, a screen printing module, an ink mixing module, a screen printing module, an exposure and development module, and a curing module.

[0020] The electroplating module includes a vertical continuous electroplating line, which is used to perform the outermost electroplating on the substrate after it has been cut. The same vertical continuous electroplating line is used to centrally produce substrates of the same part number, thereby controlling the uniformity and thickness of the copper on the surface.

[0021] The circuit processing module includes a vacuum etching line, which is used to perform pretreatment and etching of the outer layer circuits on the electroplated substrate.

[0022] The screen production module includes a screen stretching device and a tension testing device, which are used to stretch the screen in multiple directions in stages to complete the bonding and forming of the screen and the frame, and to test the tension at multiple points of the formed screen.

[0023] The ink mixing module includes a stirring device and a filtering device, which are used to add boiling water to the preset ink according to a preset ratio, complete mechanical stirring, filtering and settling, obtain solder resist ink and control its viscosity.

[0024] The screen printing module includes a screen printing machine, a nail bed, and an ultra-roughening process line. It is used to perform pre-solder resist treatment on the etched substrate using an ultra-roughening process. Within a preset time period, it uses a corresponding screen and preset squeegee parameters to perform solder resist screen printing on the non-LED bead side and the LED bead side of the substrate respectively. When screen printing on the LED bead side, a nail bed is set up under the substrate and multiple pins are arranged to control the thickness and range of the wet film ink layer after screen printing.

[0025] The exposure and development module includes a vertical oven, a laser direct imaging machine, and a development line, which are used to pre-bake, expose, and develop the screen-printed substrate in sequence.

[0026] The curing module includes a thermal light source ultraviolet curing machine, used to cure the developed substrate with ultraviolet light.

[0027] Thirdly, embodiments of this application provide a circuit board, which is a light-emitting diode ink color control circuit board, including a substrate, on which a copper circuit layer and a cured solder resist ink layer are sequentially disposed; the dry film thickness of the solder resist ink layer is within a preset thickness range, and the thickness difference within the same board is not greater than a preset range value; the circuit board is manufactured by the first aspect and / or various possible implementations of the first aspect.

[0028] The method, system, and circuit board for manufacturing LED ink color control circuit boards provided in this application embodiment stabilize the ink transfer conditions during screen printing by performing multi-directional and multiple stretching of the mesh and tension detection at multiple points on the formed screen; ensures the consistency of ink rheological properties by uniformly controlling the ratio, stirring, filtration, and viscosity of the solder resist ink; maintains the stability of the substrate surface by using an ultra-roughening process for pre-treatment of the substrate for solder resist and completing the solder resist screen printing within a preset time; disperses printing pressure and avoids local depressions by setting different exposure scales for the LED and non-LED sides and using a laser direct imaging machine for exposure; and fully completes the ink cross-linking and shaping by using a constant-speed, constant-energy curing machine with a thermal light source UV curing machine. This effectively improves the uniformity of the solder resist ink layer thickness, enhances the ink color consistency of the same batch of circuit board products, and reduces color difference defects. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0030] Figure 1 A flowchart illustrating the manufacturing method of the LED color control circuit board provided in this application;

[0031] Figure 2 A schematic diagram of the manufacturing system for a light-emitting diode (LED) ink color control circuit board provided in this application;

[0032] Figure 3 This is a schematic diagram of a circuit board structure provided in this application.

[0033] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0035] The terms "first," "second," "third," "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those illustrated or described herein.

[0036] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0037] First, let me explain the terms used in this application:

[0038] Vertical continuous electroplating line: refers to electroplating equipment in which the substrate passes through multiple electroplating tanks in a vertical state in sequence and completes the copper layer deposition in a continuous board-passing manner.

[0039] Copper uniformity refers to the consistency of the thickness of the electroplated copper layer on the substrate surface across multiple measurement points, and is usually characterized by the range of deviation between the thickness value at each point and the average thickness value.

[0040] Multi-directional multiple stretching: refers to the process of performing multiple stretching operations on the mesh in steps along the X-axis and Y-axis directions. After each single stretching is completed, the stretched state is maintained and left to stand for a preset time before the next stretching is performed.

[0041] Multi-point tension testing: This refers to a testing method that selects multiple measurement points on the surface of the forming screen and measures the tension value at each point to evaluate the uniformity of the tension distribution of the screen.

[0042] Solder resist ink: refers to ink materials that are coated on the surface of a substrate during the circuit board manufacturing process, and after exposure and development, form protective circuit patterns and prevent short circuits during soldering.

[0043] Ultra-roughening process: This refers to a surface treatment process that uses chemical treatment solutions to treat the copper surface, forming a micro-rough structure on the copper surface, in order to enhance the physical anchoring bond between the subsequent ink layer and the copper surface.

[0044] Solder resist screen printing: refers to the process of transferring solder resist ink through the mesh of a screen onto the surface of a substrate to form a wet film ink layer of a predetermined thickness.

[0045] Non-LED side: This refers to the side of the LED circuit board that does not directly support the LED chips. It mainly serves as an electrical connection and mechanical support.

[0046] LED chip side: This refers to the side of the LED circuit board that directly supports the LED chips. It is the optical working surface and has relatively strict requirements for ink color consistency.

[0047] Bed of nails: refers to a multi-support platform placed under the substrate during the screen printing process to provide substrate support in conjunction with ejector pins.

[0048] Ejector pins: These are multiple support components installed on a bed of nails, with their tops contacting the lower surface of the substrate. They distribute the substrate's weight and screen printing pressure evenly through multiple points.

[0049] Wet film ink layer: refers to the ink coating that has not been pre-baked and cured after solder resist screen printing, still contains solvent, and is in a flowable or deformable state.

[0050] Thickness range: refers to the difference between the maximum and minimum thickness of the wet film ink layer at multiple measurement points on the same substrate surface.

[0051] Laser direct imaging machine: refers to an exposure device that uses a laser beam to directly scan and expose the substrate surface, transferring the preset graphic data to the ink layer, without the need for traditional film.

[0052] Preset exposure scale: refers to the exposure energy control level or grade that is preset according to the photosensitive characteristics of the ink and the functional requirements of different surfaces.

[0053] Thermal UV curing machine: refers to a curing device that uses UV lamps as a radiation source to generate high-energy radiation in the UV band and is accompanied by infrared thermal effects, used to complete the final cross-linking and shaping of the solder resist ink layer.

[0054] Lateral etching depth: refers to the lateral dissolution depth of the ink sidewalls in the exposed area by the developing solution during the developing process.

[0055] Copper surface layer: refers to the copper layer with a preset conductive circuit pattern formed on the surface of the substrate after the outer layer circuit pretreatment and etching.

[0056] Solder resist ink layer: refers to a patterned protective ink coating formed on the surface of a substrate after screen printing, pre-baking, exposure, development and UV curing.

[0057] In the existing technology, the production of solder resist ink is carried out by means of dispersed electroplating, inconsistent detection of screen tension, adjustment of ink viscosity based on experience, non-standardization of screen printing parameters, and rough setting of curing energy. This has technical problems such as uneven ink layer thickness and obvious color difference in the same batch of circuit boards due to the discrete process parameters of each link and lack of coordinated control.

[0058] The method for manufacturing a light-emitting diode (LED) ink color control circuit board provided in this application stabilizes ink transfer conditions by performing multi-directional and multiple stretching of the mesh and multi-point tension detection of the screen. It unifies ink rheological properties by adjusting the ink according to a preset ratio and controlling the viscosity. It maintains a consistent substrate surface state by performing ultra-roughened solder resist pretreatment and completing screen printing within a preset time. It balances printing pressure by setting up a bed of nails and evenly distributing ejector pins during screen printing on the LED bead surface. It matches differentiated curing requirements by setting different exposure scales for the LED bead surface and non-LED bead surface. It fully completes ink cross-linking and shaping by using a thermal light source ultraviolet curing machine with constant speed and energy. This method solves the technical problems of uneven ink layer thickness and ink color difference caused by the cumulative conduction of discrete process parameters along the process.

[0059] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0060] Figure 1 A flowchart illustrating the fabrication method of the LED color control circuit board provided in this application is shown below. Figure 1 As shown, the manufacturing method of this LED color control circuit board includes the following steps:

[0061] Step S101: Stretch the mesh in multiple directions multiple times. After stretching, glue the mesh to the frame to obtain the screen. Detect the tension of the screen at multiple points and control the tension of the screen within the preset tension range.

[0062] Specifically, the mesh is first stretched at least twice along the X-axis, and then stretched at least twice along the Y-axis. After each stretching, it is left to stand for a preset time to allow the mesh fibers to stabilize after the internal stress is released. After all the stretching and standing cycles are completed, the mesh is bonded and fixed to a frame to form a screen. Tension is measured at multiple points on the screen surface using a multi-point detection method to control the screen tension within a preset range.

[0063] The mesh is stretched in stages along the X and Y axes on the stretching equipment. After each stretching operation, the mesh is held in a stretched state and allowed to rest, allowing the molecular chains of the mesh fibers to rearrange and the internal stress to gradually release. The number of stretching cycles and the amount of stretching are performed according to the preset process. After stretching, the mesh is bonded to the adhesive frame under constant tension. A tension meter is used to apply vertical pressure at multiple points, including the four corners and the center of the screen, to measure the tension value, ensuring that the tension value at each point is within the preset range.

[0064] Multi-directional, multiple stretching combined with static treatment allows the internal stress of the fibers to be fully released and redistributed to an equilibrium state during the stretching phase. The magnitude and uniformity of screen tension directly determine the degree of deformation and rebound speed of the screen under the action of the squeegee during screen printing. Uneven tension will lead to differences in the amount of ink transferred in different areas during the same printing stroke. By multi-directional, multiple stretching and multi-point tension detection, a screen with uniform tension and stable dimensions is obtained, providing a stable screen carrier for uniform ink transfer during screen printing. With consistent screen tension throughout and a constant screen spacing during the squeegee stroke, the amount of ink transferred through the mesh to the substrate surface remains equal in all areas, eliminating factors that may cause differences in ink thickness at the screen stage.

[0065] Step S102: Take the preset ink and add the thinner according to the preset ratio. After mechanically stirring and mixing, filter and let stand to obtain the solder resist ink. Control the viscosity of the solder resist ink within the preset viscosity range.

[0066] Specifically, a top-coat ink is used as the base ink, and it is prepared by adding a predetermined volume of thinner per kilogram of ink. After mixing the ink and thinner, a mechanical stirrer is used to stir for a predetermined time at a predetermined speed to ensure that the pigment particles, resin components, and solvents in the ink are fully mixed to form a homogeneous system. After stirring, the mixed ink is filtered through a filter to remove insufficiently dispersed particles and external impurities from the system, and then allowed to stand for a predetermined time to allow air bubbles introduced during stirring to escape naturally. The viscosity of the ink is measured using a viscometer to confirm that it is within a predetermined range.

[0067] The ink-solvent mixture is stirred at a set speed using a mechanical stirrer. The rotating blades apply shear force to the fluid, breaking up any potential agglomeration of pigment particles and promoting the full dissolution and dispersion of the resin in the solvent. The filtration stage uses a filter screen to intercept particles larger than the mesh size. The settling stage utilizes the principle that air bubbles rise to the surface and burst naturally due to buoyancy in the liquid phase, eliminating air trapped during stirring. Viscosity is measured using a rotational viscometer to assess the ink's flow resistance at a specific shear rate.

[0068] When the ink viscosity is too high, it is difficult for the ink to pass through the screen openings, resulting in a thin ink layer after printing; when the viscosity is too low, the ink flows too quickly, easily causing sagging or overspreading. Uneven pigment dispersion leads to inconsistencies in the composition of the ink system, resulting in microscopic color differences on the substrate surface after printing. The presence of impurity particles may clog the screen openings, causing localized ink loss. Mechanical stirring uses external mechanical energy to ensure uniform distribution of components at the molecular or particle scale, while filtration and settling respectively purify and stabilize the ink through physical interception and removal.

[0069] By standardizing the proportioning, stirring, filtering, settling, and viscosity testing, solder resist ink with uniform composition, high cleanliness, and stable rheological properties is obtained, providing a consistent material basis for the screen printing process. This ensures that the ink viscosity remains stable within a preset range, the pigment is evenly dispersed without impurities, and the ink filling and transfer behavior during screen printing remains highly consistent within batches, which helps to uniformly control the thickness of the wet film ink layer.

[0070] Step S103: The etched substrate is subjected to pre-solder resist treatment using an ultra-roughening process. After the pre-solder resist treatment is completed, solder resist screen printing is performed on the non-LED bead side and LED bead side of the substrate within a preset time period using a screen and preset squeegee parameters. When performing solder resist screen printing on the LED bead side, a bed of nails is set up under the substrate and multiple pins are arranged. After solder resist screen printing, the thickness of the wet film ink layer is controlled within a preset thickness range and the thickness difference is not greater than the preset difference value.

[0071] Specifically, for the substrate with completed outer layer circuitry and etching, a pre-treatment process for solder resist is first performed using an ultra-roughening technique. This process utilizes a chemical treatment solution to create a microscopic rough structure on the copper surface, enhancing the physical anchoring bond between the subsequent ink layer and the substrate. After pre-treatment, the time interval between entering the screen printing process is strictly controlled to not exceed a preset duration to prevent the cleaned and activated copper surface from being exposed to air for too long, which could lead to secondary oxidation or dust adsorption. Solder resist screen printing is performed in the order of printing on the non-LED side first, followed by the LED side. During screen printing, a pre-tested and qualified screen prepared in the previous steps is used, and the squeegee parameters are set according to preset standards. When performing screen printing on the LED side, a bed of nails is set up under the substrate, and ejector pins are arranged to provide uniform support. The number and distribution of ejector pins are configured according to preset requirements. After screen printing, a wet film thickness measuring tool is used to measure the thickness of the wet film ink layer at multiple points to ensure that the thickness is within a preset range and that the thickness difference between measurement points on the same board does not exceed a preset range value.

[0072] The ultra-roughening treatment solution reacts chemically with the copper surface, forming a micron-level uneven structure. After treatment, the substrate is cleaned and dried, and then quickly sent to the screen printing station. The screen printing machine is equipped with a squeegee with preset parameters. The squeegee moves across the screen surface at a set pressure and speed, forcing ink through the screen mesh onto the substrate surface. During screen printing on the LED bead surface, the pins on the stud bed provide multi-point support from below the substrate to prevent localized bending deformation caused by the pressure from the squeegee. Wet film thickness is measured in real time at multiple preset points on the substrate surface using a wet film roller or wet film thickness gauge.

[0073] The ultra-roughening process increases the microscopic surface area and roughness of the copper surface, providing mechanically interlocked anchoring points for the ink layer and improving ink adhesion. After cleaning and activation, the copper surface of the substrate is in a high surface energy state. With prolonged exposure to air, the copper surface gradually reacts with oxygen to form an oxide layer. Simultaneously, dust particles in the air are adsorbed onto the surface, reducing surface energy and affecting ink wetting and spreading. Preset time control aims to ensure that printing is completed when the copper surface has high surface energy and good cleanliness. During screen printing, the squeegee acts on the upper surface of the screen at a constant angle and pressure, while the lower surface of the screen maintains a set screen distance from the substrate. The ink is squeezed through the mesh and transferred to the substrate by the squeegee. The squeegee hardness, angle, and pressure together determine the degree of ink filling and transfer amount; if the squeegee hardness is too low, the ink scraping will be incomplete; angle deviation will change the direction of ink pressure; and pressure fluctuations will affect the ink extrusion amount. The LED bead surface is the optical display surface in circuit board products, requiring the highest consistency in ink color. The support system consisting of the nail bed and the ejector pins evenly transmits the weight of the substrate and the printing pressure applied by the squeegee through multi-point contact, avoiding local depressions on the substrate due to insufficient support, thereby preventing ink accumulation in the depressions or excessive ink thinning in the protrusions.

[0074] By establishing a physical foundation for ink adhesion through ultra-roughening pretreatment, maintaining substrate surface activity through time-controlled aging, and achieving uniform ink transfer on the substrate surface through standardized screen printing operations and a uniform support system for the LED bead surface, the printing quality is assessed in real time through wet film thickness detection. The ink forms a uniformly thick wet film layer on the substrate surface, with thickness differences between different areas of the same board controlled within a limited range. The ink distribution on both the LED bead and non-LED bead surfaces meets preset requirements. Ensuring the uniformity and consistency of the ink layer thickness during the screen printing process lays the foundation for consistent ink color after subsequent curing.

[0075] Step S104: The substrate after solder resist silkscreen printing is pre-baked, exposed and developed in sequence. The exposure is performed using a laser direct imaging machine, and different preset exposure scales are used for the lamp bead side and the non-lamp bead side.

[0076] Specifically, after screen printing, the substrate is first pre-baked in a vertical oven. Heating evaporates most of the solvent in the wet film ink layer, transforming it from a liquid to a semi-solid, touch-dry state. The pre-baked substrate is then exposed to a laser direct imaging machine. Different exposure scales are set for the LED bead side and the non-LED bead side during exposure. The LED bead side uses a first preset exposure scale, while the non-LED bead side uses a second preset exposure scale. During exposure, the vacuum level is maintained within a preset range, and the exposure delay is set according to process requirements. After exposure, the substrate enters the developing line, where the developer removes the ink from the unexposed areas, retaining the ink portions that have undergone photocrosslinking to form a solder resist ink pattern corresponding to the circuit pattern.

[0077] Pre-baking can be performed in a vertical oven, with the substrate placed vertically or at an angle. Hot air circulates within the oven to heat the substrate and its surface ink layer. Exposure is achieved using a direct laser imaging system. The laser beam scans and exposes the substrate surface point by point according to preset pattern data, causing the photosensitive components in the photoresist ink in the illuminated areas to undergo a polymerization reaction. Different exposure scale parameters are used for the LED side and the non-LED side to control the exposure energy. The developing line transports the substrate at a constant speed through the developing solution spray section, where unexposed ink is dissolved and removed by the developing solution.

[0078] Pre-baking removes solvent from the wet film, allowing the ink layer to initially solidify and set, preventing a decrease in image resolution due to excessive ink flow during exposure. Exposure utilizes photoinitiators to generate free radicals or cations under specific wavelengths of light, initiating cross-linking polymerization of double bonds or epoxy groups in the ink resin, making the exposed areas insoluble in the developer. Compared to traditional film contact exposure, laser direct imaging offers higher positioning accuracy and exposure uniformity. The LED bead surface, as the optical working surface, requires higher exposure resolution and specific exposure energy to ensure sharp edges and no residue; the non-LED bead surface primarily functions as electrical insulation and mechanical protection, with different exposure requirements. Separate exposure scale settings allow for matching exposure conditions to the different functional needs of the two surfaces. Vacuuming ensures tight contact between the substrate and the exposure stage, guaranteeing consistent focus. Exposure delay provides the substrate with stabilization time, preventing inertia from affecting positioning accuracy. The selective dissolution of ink in unexposed areas by the developer is based on the significant difference in dissolution rates between exposed and unexposed areas in the developer.

[0079] By pre-baking to stabilize the morphology of the ink layer, by faceted exposure to match the differentiated needs of both sides, and by development to form the final ink pattern, the ink layer has clear edges after curing, and the lamp bead side and the non-lamp bead side respectively obtain the exposure effect that matches their functional requirements.

[0080] Step S105: The developed substrate is cured with a thermal light source UV curing machine, and the curing speed and curing energy of the thermal light source UV curing machine are controlled within a preset range.

[0081] Specifically, after development, a patterned solder resist ink layer has formed on the substrate. At this point, the substrate is sent to a thermal light source UV curing machine for final curing. The UV curing machine uses a thermal light source as the radiation source. The substrate passes through the curing chamber on a conveyor belt at a set speed. Under UV irradiation, the ink layer completes full cross-linking, forming a solid solder resist ink layer with good mechanical strength and environmental resistance.

[0082] The thermal light source UV curing machine uses UV lamps as the light source, generating high-energy radiation in the UV band, accompanied by a thermal effect from infrared radiation. The substrate is conveyed by a conveyor belt at a constant speed, and the ink layer is irradiated with UV light of a preset cumulative energy density as it passes through the curing chamber. The UV light energy density is matched with the conveyor belt speed to ensure that the ink layer receives sufficient exposure energy during its passage through the chamber.

[0083] UV curing transforms solder resist ink from a semi-cured state to a fully cured state. Under UV irradiation, the photoinitiator in the ink continues to generate active species, initiating further cross-linking reactions of residual unsaturated double bonds or epoxy groups in the resin, forming a dense three-dimensional network structure. The thermal light source provides both UV radiation and infrared thermal effects, which accelerate the movement of molecular chain segments, helping to improve cross-linking density and uniformity. Insufficient UV energy density will lead to incomplete cross-linking, resulting in substandard ink layer hardness, abrasion resistance, and chemical resistance; excessive energy density may cause yellowing or embrittlement of the ink layer. The conveyor belt speed and curing energy are jointly controlled to ensure suitable and uniform curing conditions for the ink layer.

[0084] By controlling the speed and energy of UV curing with a thermal light source, the ink layer can be fully and uniformly cross-linked and shaped. The cured solder resist ink layer has high hardness, wear resistance and adhesion. Its physical and chemical properties are consistent in all areas of the substrate, and the ink color is uniform and stable.

[0085] The method for manufacturing a light-emitting diode (LED) ink color control circuit board provided in this invention eliminates the dispersion of process parameters across the entire process, including the electroplating substrate, screen carrier, ink material, pretreatment interface, screen printing pressure field, exposure conditions, and curing energy. This creates a collaborative control loop, ultimately improving the uniformity of the solder resist ink layer thickness and effectively reducing ink color difference within the same batch of LED circuit boards. This is achieved by: electroplating substrates of the same part number to ensure uniform base copper thickness; stabilizing screen tension through multi-directional stretching and multi-point tension detection; unifying ink rheological properties through standardized mixing, filtration, and viscosity control; maintaining consistent substrate interface state through ultra-coarsening pretreatment and aging control; uniformly distributing ejector pins during LED screen printing to balance printing pressure and control wet film thickness differences; setting exposure scales on different sides to match functional differences between the two sides; and fully completing ink cross-linking and shaping through constant-speed, constant-energy ultraviolet curing with a thermal light source.

[0086] In one possible implementation, the mesh is stretched in multiple directions, including step-by-step stretching along the X-axis and Y-axis, and left to stand for a preset time after each stretch; the solder resist screen printing is performed sequentially, first on the non-LED bead side and then on the LED bead side.

[0087] Specifically, the multi-directional, multi-stage stretching of the mesh is performed alternately in the X and Y axes. The mesh is first stretched along the X-axis. After each stretch, it is held in a stretched state for a preset time to allow the internal stress of the fibers to be fully released and redistributed in that stretching direction. Then, the next stretching is performed. After all the stretching along the X-axis is completed, the stretching operation is switched to the Y-axis. After all stretching cycles are completed, the mesh is bonded and fixed to a frame under constant tension to form a screen. The different number of stretches and stretch amounts set for the X and Y axes are based on a matching design based on the differences in fiber density and elastic modulus between the warp and weft directions of the mesh, and can be adjusted according to actual needs.

[0088] Tension testing is performed on the formed screen using a five-point method, which involves measuring the tension values ​​at five points: the four corners and the center of the screen. The tension value at each point must fall within the range of 24 Newtons to 30 Newtons. If the measured value at any point exceeds this range, the screen needs to be restretched or adjusted.

[0089] In the solder resist screen printing process, the printing sequence is as follows: screen printing is first performed on the non-LED bead surface. A dedicated air guide plate is used to direct the airflow generated by the squeegee movement during the printing process on the non-LED bead surface. After this, the LED bead surface is then screen printed. For LED bead surface screen printing, a bed of nails is installed under the substrate, with 100 to 300 pins arranged on the bed, maintaining a relatively uniform distribution within the area under the substrate. The screen tension is uniform and stable, and the screen spacing remains constant throughout the entire batch of screen printing operations, significantly improving the consistency of ink transfer. As the final optical working surface, the LED bead surface achieves a uniform ink layer thickness distribution under optimized sequence arrangement and balanced support conditions. The wet film ink layer thickness after screen printing is controlled within the range of 25 to 35 micrometers, and the thickness difference between measurement points on the same board is no greater than 2 micrometers.

[0090] In some examples, the three stretches along the X-axis are progressively increased in increments of 0.82 units, with a 5-minute rest period after each stretch to allow the mesh fibers to gradually relax under stress through the stretch-rest cycle. The two stretches along the Y-axis are performed in the same manner, with each stretch being 1.52 units, followed by a 5-minute rest period. For the five-point tension test, a tension meter is used, with the measuring head pressed vertically against the screen surface. Measurements are taken sequentially at five points: the four corners and the center of the screen. The tension deviation at each point is controlled within a range of 27 N as the baseline, 30 N at the upper limit, and 24 N at the lower limit. The number of ejector pins for screen printing on the LED bead surface can be flexibly selected based on the substrate size and circuit density. For example, a maximum of approximately 300 pins can be used when the substrate size is large or the circuit density is high, while a minimum of approximately 100 pins can be used when the substrate size is small or the circuit density is low, striking a balance between providing sufficient support and avoiding pin marks.

[0091] The embodiments of the present invention can significantly improve the tension uniformity of screen printing stencils, reduce tension deviations at different points on the stencil, eliminate ink volume fluctuations and ink coating thickness differences caused by uneven stencil tension, and simultaneously achieve precise control of double-sided solder resist ink coating on LED circuit boards, reduce the ink thickness difference between the two sides of the same board, reduce ink color differences and color defects caused by uneven coating, significantly improve the consistency of solder resist ink color in the same batch of products, and reduce the substrate scratch scrap rate in the screen printing process, thereby improving the product yield and operational efficiency of mass production.

[0092] In one possible implementation, prior to multi-directional, multiple stretching of the mesh, the method further includes:

[0093] a1: Perform outermost electroplating on the substrate after it has been cut. For the same part number, use the same vertical continuous electroplating line for centralized production. Control the uniformity of the copper surface within the preset uniformity range and control the thickness of the copper surface within the preset thickness range.

[0094] Specifically, after the substrate is cut, it enters the outermost electroplating stage. All substrates of the same part number are arranged on the same vertical continuous plating (VCP) line for centralized production, and it is prohibited to split them into multiple plating lines for separate processing. After electroplating, a copper thickness measuring instrument is used to detect the surface copper thickness distribution of the substrate. The surface copper thickness is verified by cross-section inspection to ensure that the surface copper thickness is within the preset control range.

[0095] The electroplating line employs a vertical continuous electroplating method, with the substrate passing through multiple electroplating tanks sequentially in a vertical orientation. The composition of the plating solution, current density, and board feed speed within each tank remain constant. Substrates of the same part number are continuously passed through the same equipment within the same production batch, avoiding additional variables introduced by parameter differences between different equipment. After electroplating, a copper thickness measuring instrument based on optical imaging principles collects surface copper thickness data at multiple locations on the substrate surface, and performs physical verification using a slicing method.

[0096] Centralized production eliminates inherent differences between different electroplating lines in terms of plating solution aging, current distribution uniformity, and equipment mechanical condition, ensuring the consistency of the copper substrate from the source. By centralizing production on the same line and inspecting the copper thickness, a quality benchmark for the copper substrate is established, providing a uniform copper layer thickness foundation for the accuracy of subsequent etching patterns. The copper thickness deviation of substrates of the same part number is limited to a preset range, effectively reducing the possibility of ink thickness differences amplifying along the process chain due to substrate unevenness, thus providing a foundational guarantee for ink color consistency.

[0097] a2: Perform pretreatment and etching of the outer layer circuitry on the electroplated substrate.

[0098] Specifically, after electroplating, the substrate enters the pretreatment process for the outer layer circuitry. During pretreatment, an oil removal function is activated to clean the copper surface and remove surface oxide layers and residues. The etching process is completed using a vacuum etching line, where a negative pressure environment enhances the uniform dissolution of the copper layer by the etching solution.

[0099] The pretreatment stage removes oil and oxides from the copper surface through chemical cleaning. The cleaned substrate then enters the vacuum etching stage. The vacuum etching line creates negative pressure in the sealed chamber, allowing the etching solution to contact the copper surface more evenly under negative pressure. Copper layers not protected by photoresist are chemically dissolved and removed, forming the preset circuit pattern.

[0100] The degreasing and cleaning processes used in the pretreatment of outer layer circuitry directly affect the uniformity of etching solution wetting on the copper surface. If oil or oxide residue remains on the copper surface, the uneven spreading rate of the etching solution will lead to localized under-etching or over-etching. Vacuum etching utilizes negative pressure to reduce the interfacial tension difference between the etching solution and the copper surface, allowing the etching reaction to proceed synchronously and uniformly in all areas of the substrate.

[0101] By synergistically controlling the cleaning of the copper surface and the vacuum etching conditions, high-precision circuit patterns are obtained during the outer layer circuit fabrication stage, providing a regular pattern substrate for subsequent solder resist screen printing. The etched circuit patterns have clear edges and uniform height across the copper surface, which helps the solder resist ink to spread evenly between the circuits during the screen printing process.

[0102] In one possible implementation, the stretching in the X-axis direction is performed 3 times, with each stretch being a first preset stretch; the stretching in the Y-axis direction is performed 2 times, with each stretch being a second preset stretch; and the preset resting time after each stretch is 5 minutes.

[0103] Specifically, the multi-directional stretching operation of the mesh is performed step-by-step in the order of first the X-axis direction, then the Y-axis direction. During X-axis stretching, a stretch increment of 0.82 units is applied each time along the X-axis. After each stretch, the mesh is held in the stretched state and allowed to rest for 5 minutes to allow the mesh fibers to relax under this stretching condition. Then, the next stretching is performed, and this cycle is repeated three times. After all three X-axis stretching cycles are completed, the mesh is rotated to the Y-axis direction for stretching, with a stretch increment of 1.52 units applied each time along the Y-axis. After stretching, the mesh is held in the stretched state and allowed to rest for 5 minutes, for a total of two cycles. After all the stretching and resting cycles are completed, the internal stress of the mesh fibers in all directions has been fully released and evenly distributed. At this point, the mesh is bonded and fixed to the adhesive frame under the current tension. After the adhesive cures, a tension-stable mesh is formed. The five-point tension test is performed on the forming screen. The tension value is measured at each point by applying vertical pressure with the tension meter head at the four corners and the center of the screen. The tension value at each point must be within the range of 24 Newtons to 30 Newtons. If the measured value at any point exceeds this range, the screen is judged to be unqualified and is rejected.

[0104] In some examples, the difference between the single stretch amount of 0.82 units in the X-axis direction and 1.52 units in the Y-axis direction is a targeted match based on the differences in fiber density and elastic modulus between the warp and weft directions of the mesh. For example, when the fiber density in the warp direction is higher than that in the weft direction, the warp direction requires a smaller stretch increment to avoid excessive stretching and fiber damage, while the higher elastic modulus in the weft direction can withstand a larger single stretch amount to fully eliminate internal stress. The choice of a 5-minute resting time is a balance between production efficiency and sufficient stress release. If the resting time is too short, the fiber stress relaxation will be insufficient; if the resting time is too long, the production efficiency will decrease and the contribution to tension improvement will become marginal. In the five-point method of detection, the tension range of the five points should be controlled within a small range. If the tension gradient between the center and the edge of the screen exceeds 3 N / cm, the screen distance will differ when the squeegee travels to different areas during screen printing, resulting in fluctuations in ink transfer. The number of ejector pins is selected from 100 to 300 depending on the substrate size and circuit density. The ejector pin layout can be appropriately increased below the high-density circuit area to provide localized targeted support.

[0105] This invention employs a multi-directional, step-by-step process involving three stretches along the X-axis and two stretches along the Y-axis, coupled with a stress relaxation mechanism that allows for 5 minutes of rest after each stretch. This achieves full release and uniform distribution of internal stress within the mesh fibers. Through a five-point tension quantitative detection method and the rejection of defective products, it ensures that all screens used in screen printing meet the tension uniformity requirements. This provides a stable benchmark for uniform ink transfer at the carrier level. The resulting screens exhibit uniform tension distribution and good stability over time. Throughout the entire batch of screen printing operations, the screen spacing remains constant, and the amount of ink transferred by the squeegee in different areas of the screen tends to be consistent. This eliminates ink layer thickness fluctuations caused by uneven tension or tension decay at the screen stage.

[0106] In one possible implementation, after mechanical stirring and mixing, the mixture is filtered using at least one stage of filter screen, and the speed of mechanical stirring is controlled within a preset speed range.

[0107] Specifically, in the ink preparation stage, a mechanical stirring device continuously stirs the ink and water mixture system at a speed of 300 to 500 revolutions per minute for 15 minutes. After stirring, the mixed ink is filtered through a 100-mesh filter to remove undispersed pigment agglomerates and particulate impurities mixed in from the outside. After filtration, it is allowed to stand for 10 minutes to allow the air bubbles introduced during stirring to escape naturally. Finally, a viscometer is used to detect and confirm that the ink viscosity is in the range of 80 dBPa to 120 dBPa.

[0108] In one possible implementation, the pretreatment and etching of the outer layer circuitry are produced on the same dedicated line. The pretreatment process is equipped with an oil removal function, and the etching is completed using a vacuum etching line.

[0109] Specifically, after electroplating, the substrate enters the outer layer circuit pretreatment and etching process. This process is completed entirely on a dedicated line on the same machine; substrates of the same part number are not allowed to be split and processed on multiple machines. The pretreatment section activates the degreasing function, using a chemical cleaning solution to degrease and remove oxidation from the copper surface, removing residual oil, fingerprints, and light oxide layers from the copper surface after electroplating. The pretreated substrate then enters the vacuum etching section. The vacuum etching line creates a negative pressure environment within a sealed chamber. Under negative pressure, the etching solution evenly contacts all areas of the copper surface, chemically dissolving and removing the copper layer not protected by the photoresist film, forming the preset circuit pattern. After etching, the substrate undergoes cleaning and drying.

[0110] In some examples, the pretreatment stage uses an alkaline degreasing solution, with the degreasing temperature controlled between 45°C and 55°C and the degreasing time controlled between 90s and 120s. The micro-etching process has a micro-etching rate controlled between 0.8μm / min and 1.2μm / min. The vacuum etching line uses an acidic copper chloride etching system, with the copper ion concentration in the etching solution controlled between 120g / L and 150g / L, the spray pressure controlled between 0.15MPa and 0.25MPa, and the vacuum degree of the etching chamber controlled at -0.06. The pressure ranges from MPa to -0.04MPa, and the substrate conveying speed is controlled between 2.5m / min and 3.5m / min. The preset speed range for mechanical stirring is 800r / min to 1200r / min, and the stirring time is controlled between 15min and 25min. The filtration process uses two-stage series filters, with the first-stage filter having a mesh size of 100 mesh and the second-stage filter having a mesh size of 200 mesh. For all substrates in the same production batch, the pretreatment and etching of the outer layer circuits are completed on the same dedicated line machine without cross-line transfer.

[0111] In the substrate circuit processing stage, substrates that have completed electroplating in the same batch are sent to the same dedicated line machine. First, the surface cleanliness and micro-roughness of the substrate are standardized and adjusted through the integrated pre-processing section. Then, the circuit pattern is accurately formed through the vacuum etching line integrated in the same machine. There is no cross-line transfer throughout the process, so the process parameters of the circuit processing of the same batch of substrates are completely unified.

[0112] In the ink raw material preparation stage, after the ink and thinner are mixed according to a fixed ratio, the entire process is mechanically stirred in a closed environment at a preset speed. After stirring, impurities are filtered through at least one filter screen, and then the ink is allowed to stand and degas to obtain solder resist ink, thus achieving standardized control of the performance parameters of the same batch of ink.

[0113] This embodiment integrates pretreatment and etching on the same dedicated line, eliminating differences in process parameters between different machines and changes in substrate state during the transfer process. This achieves a high degree of uniformity in the microscopic state of the substrate surface in the same batch, providing a consistent substrate foundation for uniform coating of solder resist ink. The application of vacuum etching process ensures the uniformity of circuit forming accuracy and substrate surface roughness, avoiding ink film thickness deviation caused by uneven etching.

[0114] By precisely controlling the mechanical stirring speed and using a multi-stage filtration process, the viscosity and dispersibility of solder resist ink are standardized and controlled, eliminating the differences in screen printing coating caused by fluctuations in the performance of ink raw materials, and locking in the core control variable of ink color consistency from the raw material end.

[0115] This invention integrates the pre-processing and etching of outer circuits on a dedicated line on the same machine. Combined with precise control of ink mechanical stirring and multi-stage filtration processes, it eliminates batch-to-batch fluctuations in substrate surface condition and ink raw material performance. This achieves standardized control of circuit forming accuracy and ink performance, providing a stable substrate and raw material foundation for consistent solder resist ink color. It significantly improves the ink color uniformity of circuit board products in the same batch, reduces the incidence of color difference defects, and improves the yield and process smoothness of mass production.

[0116] In one possible implementation, the running speed of the ultra-roughening process is controlled within a preset speed range, and the operation time after the anti-welding pretreatment is completed is controlled not to exceed a preset time threshold.

[0117] Specifically, the running speed of the ultra-roughening process is controlled within a preset speed range to form a uniform micro-rough structure on the substrate surface. The substrate that has completed the ultra-roughening solder resist pretreatment and has been dried by hot air is immediately transferred to the screen printing waiting station. The interval between the completion of the pretreatment drying and the start of the solder resist screen printing operation is strictly controlled so that the operation time does not exceed the preset time threshold.

[0118] In one possible implementation, the uniformity of vacuum etching is controlled to be above a preset etching uniformity threshold.

[0119] Specifically, the substrate with the outermost electroplating layer is sent to the vacuum etching line for circuit etching. During the etching process, the uniformity of vacuum etching is stably controlled above the preset etching uniformity threshold by matching the correspondence between the etching solution composition, spray pressure, cavity vacuum degree and substrate conveying speed. After etching and multi-stage washing and drying, the substrate is directly sent to the ultra-roughening treatment line for solder resist pretreatment by locking the matching relationship between ultra-roughening solution parameters, temperature and equipment operating speed.

[0120] In some examples, the preset etching uniformity threshold is 95%, the copper ion concentration in the etching solution is controlled at 120 g / L to 150 g / L, the hydrochloric acid concentration is controlled at 80 g / L to 100 g / L, the vacuum degree of the etching chamber is controlled at -0.06 MPa to -0.04 MPa, the pressure difference between the upper and lower sprays is controlled within 0.02 MPa, and the substrate conveying speed is controlled at 2.5 m / min to 3.5 m / min; the preset speed range for the ultra-roughening process is 2.0 m / min to 3.0 m / min, and the ultra-roughening solution uses sulfuric acid. - The hydrogen peroxide system has a sulfuric acid concentration controlled between 80 g / L and 120 g / L, a hydrogen peroxide concentration controlled between 25 g / L and 35 g / L, and a solution temperature controlled between 30°C and 35°C. The preset time threshold after the solder resist pretreatment is 30 min, and the surface roughness of the substrate after pretreatment drying is controlled within the range of 0.3 μm to 0.6 μm. In mass production scenarios, the operation time after the solder resist pretreatment is controlled within 15 min, the ultra-roughening process running speed is fixed at 2.5 m / min, and the vacuum etching uniformity is stable at over 97%.

[0121] By matching the chemical parameters, cavity vacuum degree, spray pressure and conveying speed of the vacuum etching line, the process matching relationship of the etching process is adjusted so that the etching uniformity can be stably reached above the preset threshold, and the uniform forming of the circuit pattern is completed.

[0122] For the etched substrate, by locking the correspondence between the parameters of the ultra-roughening solution and the operating speed of the equipment, the operating speed is stably controlled within a preset range, forming a uniform micro-rough structure on the substrate surface, thus completing the substrate surface modification before solder resist. The third stage is the operation time control stage. For the substrate that has completed the pre-treatment of solder resist, the interval between the drying of the pre-treatment and the start of the solder resist screen printing is strictly controlled to avoid oxidation and contaminant adhesion on the substrate surface and to ensure the consistency of the surface state of the substrate when it enters the screen printing process.

[0123] By controlling the uniformity of vacuum etching, the differences in surface microstructure in different areas of the entire substrate can be eliminated, ensuring the overall consistency of the substrate surface energy after circuit formation. By controlling the range of ultra-roughening process speed, a uniform and stable micro-rough structure can be formed on the substrate surface, providing a consistent adhesion base for solder resist ink and ensuring the leveling and uniformity of ink application during the ink coating process.

[0124] By controlling the upper limit of the working time after solder resist pretreatment, the surface condition of the substrate can be prevented from changing with the exposure time, ensuring that the surface activity and cleanliness of all substrates in the same batch are consistent when entering the screen printing process, and eliminating various variables that cause ink color differences from the pretreatment process before solder resist.

[0125] This invention achieves consistent control over the microscopic state, activity, and cleanliness of the substrate surface before solder resist by implementing three levels of precise collaborative management: uniformity of vacuum etching, speed of ultra-roughening process, and post-treatment time before solder resist processing. This eliminates differences in ink adhesion and leveling caused by previous processes, locks in the core control point of solder resist ink color consistency from the source, significantly improves the uniformity of solder resist ink color in the same batch of circuit board products, reduces the incidence of color difference defects, and improves the protective performance and mass production stability of the circuit board.

[0126] In one possible implementation, pre-baking is performed using a vertical oven, the vacuum level is controlled within a preset vacuum level range during exposure, and the amount of side etching is controlled not to exceed a preset side etching threshold during development.

[0127] Specifically, the substrate with completed solder resist screen printing is first sent to a vertical oven for pre-baking. Hot air circulation ensures uniform temperature control, removing volatile organic solvents from the solder resist ink and transforming it into a stable semi-cured state. After cooling to room temperature, the pre-baked substrate is sent to a laser direct imaging machine for exposure. Before exposure, the equipment cavity is evacuated to maintain a stable vacuum level within a preset range. Then, for the LED and non-LED sides of the substrate, corresponding preset exposure scales are matched to complete the pattern transfer exposure, causing the ink in the exposed areas to undergo light-induced intermolecular polymerization and cross-linking reactions. The exposed substrate is immediately sent to the developing line, where alkaline developer dissolves and removes uncured ink from unexposed areas, completing the development and shaping of the circuit pattern and solder resist windows. During development, the lateral etching amount at the circuit edges is strictly controlled to ensure it does not exceed a preset lateral etching threshold. After development, the substrate is washed and dried, and then immediately sent to a thermal light source UV curing machine for final UV curing. By precisely controlling the curing speed and energy, the solder resist ink is completely cross-linked and cured, forming a stable cured film layer.

[0128] In some examples, the vertical oven uses a top-to-bottom vertical hot air circulation mode, with a pre-baking temperature controlled at 75℃ and a baking time of 50 minutes, and a hot air velocity controlled at 1.5m / s to 2.0m / s; the preset vacuum level during exposure is 300mmHg to 370mmHg, with an exposure delay of 1 to 2 seconds after vacuuming; the exposure wavelength of the laser direct imaging machine is 355nm, and the exposure scale difference between the LED bead surface and the non-LED bead surface is controlled at 10% to 15%; the preset side etching threshold during development is 25μm, and the developer is a sodium carbonate aqueous solution with a quality... The concentration is controlled between 0.8% and 1.2%, the developing temperature is controlled between 28℃ and 32℃, and the developing spray pressure is controlled between 0.1MPa and 0.2MPa. During the UV curing process, the curing speed of the thermal light source UV curing machine is preset to a range of 1.5m / min to 2.5m / min, and the curing energy is preset to a range of 2500mJ / cm² to 3500mJ / cm². In mass production scenarios, the curing speed is fixed at 2m / min, and the curing energy is fixed at 3000mJ / cm². All substrates in the same production batch use the same set of process parameters to complete the pre-baking, exposure, developing, and UV curing operations.

[0129] The first stage of this embodiment is the pre-baking and shaping stage, in which a vertical oven is used to uniformly heat the screen-printed substrate. The pre-baking temperature and time are precisely controlled to ensure that the organic solvents in the ink evaporate evenly, forming a stable semi-cured state and avoiding uneven local solvent residue. The second stage is the exposure and imaging stage, in which the exposure chamber is first evacuated to ensure that the exposure film and the substrate surface are tightly adhered. The vacuum degree is stably controlled within a preset range. Then, the corresponding exposure scale is matched according to the structural characteristics of different board surfaces to complete the precise pattern transfer exposure. The third stage is the developing and shaping stage, in which standardized developing solution parameters and spray pressure control are used to uniformly remove uncured ink. At the same time, the amount of lateral etching at the edge of the circuit is strictly limited to ensure the edge regularity and thickness uniformity of the solder resist ink layer. The fourth stage is the final curing stage, in which a thermal light source ultraviolet curing machine is used. By matching the curing speed and curing energy, the semi-cured ink completes full cross-linking and polymerization to form a stable three-dimensional network structure. The same batch of substrates uses the same process parameters throughout the process, with no fluctuations in parameters within the batch.

[0130] This invention achieves standardized control of solder resist ink from semi-cured setting to complete cross-linking curing through a comprehensive process of pre-baking selection in a vertical oven, precise control of exposure vacuum, rigid limitation of developing side etching amount, and matching and optimization of UV curing parameters. This eliminates ink color differences caused by fluctuations in process parameters at each stage of curing, significantly improves the consistency of solder resist ink color in the same batch of circuit board products, reduces the incidence of color difference defects, and enhances the performance stability of the solder resist ink layer and the protective reliability of the circuit board.

[0131] In one possible implementation, the pre-baking temperature is controlled at 75°C and the duration is 50 min; the curing speed of the thermal light source UV curing machine is controlled at 2 m / min and the curing energy is 3000 mJ / cm²; the vacuum degree during the exposure process is controlled at 300 mmHg to 370 mmHg, and the lateral etching amount during the development process is controlled at no more than 25 μm.

[0132] Specifically, after the double-sided solder mask screen printing is completed, the substrate is allowed to stand for 3 to 5 minutes to level, then vertically arranged in a single layer and sent into a vertical oven. The oven maintains a constant hot air temperature of 75°C throughout the process. Timing begins after the substrate enters the oven, and it is continuously baked at this temperature for 50 minutes. During baking, vertical hot air circulation is maintained, and the temperature difference inside the oven is controlled within ±2°C. After the pre-baked substrate is removed from the oven, it is allowed to cool naturally to 23±2°C in a dust-free environment before being sent to a laser direct imaging machine. The exposure chamber is first closed and the vacuum program is started. The vacuum level in the chamber is kept stable between 300 mmHg and 370 mmHg. Afterwards, the exposure program is started, and the pattern transfer exposure between the LED bead surface and the non-LED bead surface of the substrate is completed according to the preset exposure scale. The exposed substrate is sent to the developing line within 10 minutes, and the uncured ink is dissolved and removed by sodium carbonate developer. During the developing process, the dissolution width of the circuit pattern edge is controlled in real time to ensure that the lateral etching amount is no more than 25μm. After the developing is completed and the substrate is washed with water and dried with hot air, it is immediately sent to the thermal light source ultraviolet curing machine. The equipment drives the substrate through the curing chamber at a constant conveying speed of 2m / min. The curing energy output by the chamber is stably controlled at 3000mJ / cm² to complete the complete cross-linking and curing of the solder resist ink.

[0133] In some examples, the hot air circulation speed of the vertical oven is controlled between 1.5 m / s and 2.0 m / s. Before entering the oven, the substrates must be cleaned of surface dust. After entering the oven, they are vertically inserted in a single layer into a special fixture, with a spacing of no less than 20 mm between boards. The exposure light source wavelength of the laser direct imaging machine is 355 nm. The exposure scale for the non-LED surface is 45% to 50%, and the exposure scale for the LED surface is 55% to 60%. The stabilization time of the vacuum program is no less than 15 seconds, and the vacuum fluctuation in the cavity during exposure does not exceed ±10 mmHg. The developer is a sodium carbonate aqueous solution with a mass concentration of 1.0% ± 0.1%. The developing temperature is controlled at 30±2℃, the spray pressure is controlled at 0.15MPa±0.03MPa, and the developing point is controlled at 50% to 60%. The thermal light source UV curing machine uses a high-pressure mercury lamp as the curing light source with a power of 8kW. The light sources are symmetrically arranged on the upper and lower parts of the curing chamber, and the curing energy deviation on the upper and lower surfaces of the substrate does not exceed ±5%. During mass production, all substrates in the same production batch are pre-baked, exposed, developed, and UV cured using fixed parameters without adjusting the process values. The entire operation is carried out in a Class 1000 cleanroom with an ambient temperature controlled at 23±2℃ and a relative humidity controlled at 50±5%.

[0134] This embodiment rigidly limits the pre-baking parameters to 75℃ and 50min, providing a stable and consistent semi-cured foundation for the photocuring reaction of the solder resist ink, eliminating differences in the pre-baking state of substrates in the same batch; by controlling the vacuum level range of 300mmHg to 370mmHg, the consistency of the ultraviolet light transmission path during exposure is ensured, achieving uniform control of the photocrosslinking degree of the ink across the entire substrate; by limiting the lateral etching amount threshold to no more than 25μm, the thickness uniformity and edge regularity of the solder resist ink layer at the edge of the circuit pattern are ensured, avoiding appearance differences caused by local uneven thickness; by precisely matching the curing speed of 2m / min and the curing energy of 3000mJ / cm², the degree of complete curing of the solder resist ink on all substrates in the same batch is highly consistent, forming a cured film layer with uniform appearance and performance.

[0135] This invention establishes a standardized closed-loop control system for the curing and molding of solder resist ink by quantitatively and rigidly limiting the core process parameters throughout the entire process, including pre-baking temperature and duration, exposure vacuum degree, developing side etching amount, and UV curing speed and energy. This eliminates the differences in ink curing degree caused by fluctuations in process parameters, significantly improves the consistency of solder resist ink color in the same batch of circuit board products, reduces the incidence of color difference defects, and at the same time improves the performance stability of the solder resist ink layer and the protective reliability of the circuit board.

[0136] In one possible implementation, the preset ink is a photosensitive ink; the preset squeegee parameters include a squeegee hardness of 70°, a squeegee angle of 60°, and a printing pressure of 4 kg / cm²; when multiple ejector pins are deployed, the number of ejector pins is controlled to be within the range of 100 to 300.

[0137] Specifically, before the solder resist screen printing operation, a photosensitive ink suitable for the solder resist process of LED circuit boards is selected. The ink is mixed and stirred according to the preset ratio to obtain screen printing ink that meets the viscosity requirements. At the screen printing station, a polyurethane squeegee of the corresponding specification is selected. The squeegee is installed and adjusted according to the preset parameters, locking the squeegee hardness at 70° and fixing the contact angle between the squeegee and the screen at 60°. During the screen printing process, the printing pressure of the squeegee is stably controlled at 4 kg / cm². For the screen printing operation on the LED bead surface, a corresponding number of ejector pins are arranged on the substrate support table of the screen printing machine. The number of ejector pins is controlled within the range of 100 to 300. The ejector pins are arranged in a uniform matrix. During the screen printing process, the ejector pins are in close contact with the non-graphic area of ​​the substrate to provide uniform support for the substrate. Then, the adjusted squeegee and ink are used to complete the solder resist ink coating operation on the LED bead surface and the non-LED bead surface of the substrate.

[0138] In some examples, the photoresist ink is an epoxy-modified acrylate UV-curable solder resist ink, adapted for 355nm wavelength laser direct imaging exposure process. The viscosity of the ink, after mixing at 25℃, is controlled within the range of 150dPas to 200dPas. The squeegee is a wear-resistant polyurethane squeegee with a blade thickness controlled between 0.2mm and 0.3mm. The squeegee length extends 50mm to 80mm beyond the width of the substrate printing area. During screen printing, the squeegee's running speed is controlled between 100mm / s and 150mm / s, and the printing gap between the screen and the substrate is controlled between 3mm and 4mm. For standard LED circuit board substrates with dimensions of 500mm×600mm, the number of ejector pins is fixed at 200, the pin diameter is 2mm, and the pin height tolerance is controlled within ±0.02mm. The ejector pins are arranged to avoid the pads, circuits, and vias of the substrate. For substrates with dimensions of 400mm×500mm, the number of ejector pins is 150. For large-size substrates with dimensions of 600mm×700mm, the number of ejector pins is 280. The entire screen printing operation is completed in a Class 1000 cleanroom, with the ambient temperature controlled at 23±2℃ and the relative humidity controlled at 50±5%.

[0139] By selecting photoresist inks, a stable raw material base suitable for subsequent curing processes is provided for solder resist screen printing, ensuring color consistency and curing stability after ink film formation. Precise quantitative control of three core parameters—squeegee hardness, angle, and printing pressure—achieves standardized control of ink transfer during screen printing, eliminating ink volume differences caused by squeegee parameter fluctuations and ensuring uniform ink coating thickness across the entire substrate. Controlling the number of ejector pins from 100 to 300 adapts to the support requirements of substrates of different sizes, eliminating substrate deformation during screen printing, ensuring consistent printing gaps across the entire board, and avoiding localized coating thickness deviations.

[0140] This invention achieves standardized control of ink transfer during solder resist screen printing and effective elimination of substrate deformation by selecting photoresist inks suitable for the process, precisely limiting the core parameters of the squeegee, and controlling the range of the number of screen printing pins on the LED surface. This ensures the consistency of solder resist ink coating thickness across the entire board and batch, significantly improves the uniformity of solder resist ink color in the same batch of circuit board products, reduces the incidence of color difference defects, and improves the operational stability and product yield of large-scale mass production.

[0141] Figure 2 This application provides a schematic diagram of the manufacturing system for a light-emitting diode (LED) color control circuit board, as shown below. Figure 2As shown, this application embodiment also provides a manufacturing system 20 for a light-emitting diode ink color control circuit board. The manufacturing system is used to implement the above-mentioned method for manufacturing a light-emitting diode ink color control circuit board, including: an electroplating module 201, a circuit processing module 202, a screen printing module 203, an ink mixing module 204, a screen printing module 205, an exposure and development module 206, and a curing module 207.

[0142] Electroplating module 201 includes a vertical continuous electroplating line, which is used to perform the outermost electroplating on the substrate after it has been cut. The same vertical continuous electroplating line is used to centrally produce substrates of the same part number, and to control the uniformity and thickness of the copper on the surface.

[0143] The circuit processing module 202 includes a vacuum etching line for pre-processing and etching the outer layer circuits of the electroplated substrate.

[0144] The screen production module 203 includes a screen stretching device and a tension testing device, which are used to stretch the screen in multiple directions in stages to complete the bonding and forming of the screen and the frame, and to test the tension at multiple points of the formed screen.

[0145] The ink mixing module 204 includes a stirring device and a filtering device, which is used to add boiling water to the preset ink according to a preset ratio, complete mechanical stirring, filtering and settling, to obtain solder resist ink and control its viscosity.

[0146] The screen printing module 205 includes a screen printing machine, a stapler and an ultra-roughening process line. It is used to perform solder resist pretreatment on the etched substrate using an ultra-roughening process. Within a preset time, it uses the corresponding screen and preset squeegee parameters to perform solder resist screen printing on the non-LED side and LED side of the substrate respectively. When screen printing on the LED side, a stapler is set up under the substrate and multiple pins are arranged to control the thickness and range of the wet film ink layer after screen printing.

[0147] The exposure and development module 206 includes a vertical oven, a laser direct imaging machine, and a development line, which are used to pre-bake, expose, and develop the screen-printed substrate in sequence.

[0148] The curing module 207 includes a thermal light source ultraviolet curing machine for ultraviolet curing the developed substrate.

[0149] Figure 3 A schematic diagram of a circuit board structure is provided in this application, such as... Figure 3 As shown, this application embodiment also provides a circuit board, which is a light-emitting diode (LED) ink color control circuit board, including:

[0150] Substrate 301, with a copper circuit layer 302 and a cured solder resist ink layer 303 sequentially disposed on the surface of substrate 301;

[0151] The dry film thickness of the solder resist ink layer 303 is within the preset thickness range, and the thickness difference within the same board is not greater than the preset range value;

[0152] The circuit board is manufactured using the aforementioned method for producing a light-emitting diode color control circuit board.

[0153] It should be noted that the numerical values ​​and ranges involved in this application are approximate values. Due to the influence of the manufacturing process, there may be a certain range of errors, which can be considered negligible by those skilled in the art.

[0154] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0155] In the description of this application, it should be understood that the terms “center,” “length,” “width,” “thickness,” “top,” “bottom,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “vertical,” “horizontal,” “inner,” “outer,” “axial,” and “circumferential,” etc., used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the indicated position or component must have a specific orientation, or a specific structure and operation, and therefore should not be construed as a limitation of the present invention.

[0156] The devices or elements referred to in the embodiments of this application or implied herein must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of this application. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise precisely specified.

[0157] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0158] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0159] The term "multiple" in this article refers to two or more. The term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Furthermore, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects; in formulas, the character " / " indicates a "division" relationship between the preceding and following related objects.

[0160] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application.

[0161] It is understood that, in the embodiments of this application, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0162] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for manufacturing a light-emitting diode (LED) ink color control circuit board, characterized in that, include: The mesh is stretched multiple times in multiple directions. After stretching, the mesh is glued to the frame to obtain the screen. Tension is detected at multiple points on the screen to control the tension of the screen within a preset tension range. Take a preset ink and add boiling water according to a preset ratio. After mechanically stirring and mixing, filter and let stand to obtain solder resist ink. Control the viscosity of the solder resist ink within a preset viscosity range. An ultra-roughening process is used to perform pre-solder resist treatment on the etched substrate. After the pre-solder resist treatment is completed, solder resist screen printing is performed on the non-LED bead side and the LED bead side of the substrate within a preset time period using the screen and preset squeegee parameters. When performing the solder resist screen printing on the LED bead side, a bed of nails is set up under the substrate and multiple pins are arranged. After the solder resist screen printing, the thickness of the wet film ink layer is controlled within a preset thickness range and the thickness difference is not greater than a preset difference value. The substrate after solder resist silkscreen printing is pre-baked, exposed and developed in sequence. The exposure is performed using a laser direct imaging machine, and different preset exposure scales are used for the lamp bead side and the non-lamp bead side. The developed substrate is cured with a thermal light source UV curing machine, and the curing speed and curing energy of the thermal light source UV curing machine are controlled within a preset range.

2. The method for manufacturing a light-emitting diode (LED) ink color control circuit board according to claim 1, characterized in that, The process of stretching the mesh in multiple directions includes step-by-step stretching operations along the X-axis and Y-axis, with a preset resting time after each stretch; the solder resist silkscreen is applied sequentially, first to the non-LED bead surface and then to the LED bead surface.

3. The method for manufacturing a light-emitting diode ink color control circuit board according to claim 2, characterized in that, The X-axis stretching is performed 3 times, with each stretch being a first preset stretch; the Y-axis stretching is performed 2 times, with each stretch being a second preset stretch; and the preset resting time after each stretch is 5 minutes.

4. The method for manufacturing a light-emitting diode color control circuit board according to claim 1, characterized in that, After mechanical stirring and mixing, the mixture is filtered using at least one stage of filter screen, and the speed of mechanical stirring is controlled within a preset speed range.

5. The method for manufacturing a light-emitting diode (LED) ink color control circuit board according to claim 4, characterized in that, The operating speed of the ultra-roughening process is controlled within a preset speed range, and the operation time after the anti-welding pretreatment is completed does not exceed a preset time threshold.

6. The method for manufacturing a light-emitting diode ink color control circuit board according to claim 1, characterized in that, The pre-baking is carried out in a vertical oven, the vacuum level is controlled within a preset vacuum level range during the exposure process, and the side etching amount is controlled not to exceed a preset side etching threshold during the development process.

7. The method for manufacturing a light-emitting diode ink color control circuit board according to claim 6, characterized in that, The pre-baking temperature is controlled at 75℃ and the time is controlled at 50min; the curing speed of the thermal light source UV curing machine is controlled at 2m / min and the curing energy is controlled at 3000mJ / cm²; the vacuum degree during the exposure process is controlled at 300mmHg to 370mmHg; and the lateral etching amount during the development process is controlled at no more than 25μm.

8. The method for manufacturing a light-emitting diode ink color control circuit board according to claim 7, characterized in that, The preset ink is a photosensitive ink; the preset squeegee parameters include squeegee hardness of 70°, squeegee angle of 60°, and printing pressure of 4 kg / cm²; when multiple ejector pins are deployed, the number of ejector pins is controlled to be within the range of 100 to 300.

9. A manufacturing system for a light-emitting diode (LED) ink color control circuit board, characterized in that, The manufacturing system is used to implement the manufacturing method according to any one of claims 1 to 8, and includes: an electroplating module, a circuit processing module, a screen printing module, an ink mixing module, a screen printing module, an exposure and development module, and a curing module; The electroplating module includes a vertical continuous electroplating line, which is used to perform the outermost electroplating on the substrate after it has been cut. The same vertical continuous electroplating line is used to centrally produce substrates of the same part number, thereby controlling the uniformity and thickness of the copper on the surface. The circuit processing module includes a vacuum etching line, which is used to perform pretreatment and etching of the outer layer circuits on the electroplated substrate. The screen production module includes a screen stretching device and a tension testing device, which are used to stretch the screen in multiple directions in stages to complete the bonding and forming of the screen and the frame, and to test the tension at multiple points of the formed screen. The ink mixing module includes a stirring device and a filtering device, which are used to add boiling water to the preset ink according to a preset ratio, complete mechanical stirring, filtering and settling, obtain solder resist ink and control its viscosity. The screen printing module includes a screen printing machine, a nail bed, and an ultra-roughening process line. It is used to perform pre-solder resist treatment on the etched substrate using an ultra-roughening process. Within a preset time period, it uses a corresponding screen and preset squeegee parameters to perform solder resist screen printing on the non-LED bead side and the LED bead side of the substrate respectively. When screen printing on the LED bead side, a nail bed is set up under the substrate and multiple pins are arranged to control the thickness and range of the wet film ink layer after screen printing. The exposure and development module includes a vertical oven, a laser direct imaging machine, and a development line, which are used to pre-bake, expose, and develop the screen-printed substrate in sequence. The curing module includes a thermal light source ultraviolet curing machine, used to cure the developed substrate with ultraviolet light.

10. A circuit board, characterized in that, The circuit board is a light-emitting diode (LED) color control circuit board, comprising: A substrate, wherein a copper circuit layer and a cured solder resist ink layer are sequentially provided on the surface of the substrate; The dry film thickness of the solder resist ink layer is within the preset thickness range, and the thickness difference within the same board is not greater than the preset range value. The circuit board is manufactured by the method of any one of claims 1 to 8 for manufacturing a light-emitting diode ink color control circuit board.

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