PCB anti-soldering window manufacturing method

Abstract

The application discloses a PCB anti-soldering window manufacturing method, which comprises the following steps: placing the etched circuit board in the normal flow through AOI→ anti-soldering pretreatment→ two-side whole board silk screen ink→ pre-baking→ text→ post-baking solidification→ plate forming to obtain a unit plate; providing a laser anti-soldering window device and a controller, placing the unit plate needing anti-soldering window on the machining platform of the laser anti-soldering window device; collecting the positioning holes of four corners of the unit plate as positioning targets in the automatic expansion and contraction mode, simulating the actual window opening position positioned according to the targets, and adjusting the graphic proportion of the window to be opened according to the simulated window opening position; and controlling the laser anti-soldering window device to perform anti-soldering window machining according to the simulated window opening position and the graphic proportion of the window to be opened after adjustment. The PCB anti-soldering window manufacturing method provided by the application first forms the unit plate by plate forming, and then removes the solder resist layer by laser technology to form the window opening graphic, thereby improving the machining precision, saving the chemical reaction link of the developing chemical water, saving the exposure film, the developing chemical water and the chemical water environmental protection treatment cost, simplifying the manufacturing process, and reducing the influence of the chemical water on the health of workers in the production process.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing technology, specifically to a method for creating a solder mask opening on a PCB. Background Technology

[0002] LEDs are now widely used in lighting, LCD backlighting, and displays, gaining attention for their energy efficiency and practicality. As LED technology continues to advance, this provides an even larger market for LED circuit boards.

[0003] In the LED circuit board manufacturing process, the distance control between the LED chip PAD and the molding edge is strictly required and has always been a difficult point in industry control. The tolerance for the distance control between the edge PAD and the molding edge is generally between ±0.075mm and ±0.1mm. If it exceeds this range, there will be black screen or striped color difference in the display screen, which will affect the viewing effect.

[0004] Regarding the control of the distance from the PAD to the molding edge of LED circuit boards, the industry common practice is as follows:

[0005] (1) Simulate the production board production method, first open the test board multiple times to capture expansion and contraction data, and then obtain a pre-stretched drill strip for drilling from the first process (drilling);

[0006] (2) The expansion and contraction coefficients of each process are measured in batches to obtain the film coefficients;

[0007] (3) The production parameters for each process are tightened based on the parameters of the test plate;

[0008] (4) The size of the solder resist window is determined by referring to the test plate results. The shape and size of the first PAD are confirmed in batches and multiple times. The shape and size of the window need to be optimized multiple times, and then exposed and developed to complete the solder resist window.

[0009] (5) Before molding, the distance from PAD to molding edge of the first piece of each batch is sampled and tested to see if it is within the tolerance control range. Then, mass production is carried out, and sampling is performed during the process. FQC performs full testing. If the distance exceeds the tolerance, the piece is scrapped.

[0010] The existing molding methods have the following problems:

[0011] 1. The production process of LED light boards is long and involves multiple steps. If there is a deviation in the expansion and contraction of a single step, it will affect the difference between the PAD and the forming edge.

[0012] 2. When each batch of boards arrives at the outer layer circuitry and solder mask, expansion and contraction must be measured and film produced for each batch. Then, the first piece must be confirmed. Only after it passes the first piece inspection can mass production begin. Sometimes, 3-5 sets of film are needed for a single batch to pass inspection. Film costs are high and efficiency is low.

[0013] 3. The solder mask opening of the LED PAD is formed by transferring the film exposure pattern and then reacting with solder mask developing solution. The developing solution and environmental treatment costs are high.

[0014] 4. During molding, the difference between the PAD and the molding edge needs to be measured multiple times on the first piece to ensure that it is within the tolerance control range before mass production. This is because the first piece is measured on a certain proportion of boards and cannot represent the expansion and contraction of the entire batch of boards. There will still be cases of expansion and contraction exceeding the tolerance during mass production, which will affect the tolerance of the distance between the PAD and the molding edge of the light board.

[0015] Therefore, the purpose of this invention is to provide a new method for manufacturing PCB solder mask openings to solve the above-mentioned technical problems. Summary of the Invention

[0016] The technical problem to be solved by the present invention is to provide a method for manufacturing PCB solder mask opening, which adopts laser solder mask opening technology, improves the tolerance accuracy of the distance between PAD and the forming edge, and enables the PCB board to meet the design requirements of high-density, miniaturized electronic devices.

[0017] The technical solution of the present invention is as follows:

[0018] A method for fabricating a solder mask opening on a PCB includes the following steps:

[0019] Step S1: The etched circuit board is processed according to the normal process of AOI → pre-soldering treatment → screen printing ink on both sides of the board → pre-baking → text → post-baking curing → PCB forming to obtain the unit board.

[0020] Step S2: Provide a laser anti-welding window opening device and controller, place the unit board that needs to be anti-welding windowed on the processing platform of the laser anti-welding window opening device, the laser anti-welding window opening device includes a CCD alignment device;

[0021] Step S3: Retrieve the engineering data stored in the controller. The CCD alignment device collects the positioning holes at the four corners of the unit board as positioning targets. Based on the collected positioning targets, the expansion and contraction coefficient of the circuit board is calculated through the automatic expansion and contraction mode, thereby simulating the actual window opening position. The graphic scale of the window to be opened is adjusted according to the simulated window opening position.

[0022] Step S4: Based on the simulated window opening position and the adjusted window opening graphic ratio, control the laser anti-welding window opening device to perform anti-welding window opening processing according to the preset path.

[0023] Furthermore, the laser anti-welding window opening device includes a laser emitter, a laser optical path, a scanning galvanometer, a scanning field mirror, a vacuum adsorption platform, a dust collection device, an X-direction moving axis, a Y-direction moving axis, a galvanometer Z-direction moving axis, and a CCD alignment device;

[0024] The laser emitter transmits the generated laser beam to the scanning galvanometer through the laser optical path. The scanning galvanometer is used to control the position and direction of the laser beam. The scanning field mirror is connected to the scanning galvanometer and is used to adjust the laser focal length and the size of the laser beam.

[0025] The vacuum adsorption platform is used to fix the circuit board to be processed, and the dust collection device is located on one side of the vacuum adsorption platform to remove dust from the surface of the circuit board.

[0026] The Y-direction moving axis is used to adjust the motion trajectory of the scanning galvanometer and the scanning field mirror in the horizontal Y direction; the X-direction moving axis is used to adjust the motion trajectory of the vacuum adsorption platform in the horizontal X direction; and the Z-direction moving axis of the galvanometer is used to adjust the motion trajectory of the scanning galvanometer and the scanning field mirror in the Z direction.

[0027] The CCD alignment device is coaxial with the scanning galvanometer and is used to grasp the positioning target to achieve positioning.

[0028] Furthermore, multiple Mark points are set within the unit board to form a multi-point alignment mode. The unit board is divided into several regions based on the different positioning targets collected by the CCD alignment device. The actual window opening position of each region block is simulated using the positioning targets of each region block, and the graphic scale of the window to be opened in the region block is adjusted according to the simulated window opening position.

[0029] Furthermore, when the number of positioning targets N satisfies 8≤N≤100, multiple region blocks are formed, and the number of positioning targets in each region block is ≥4.

[0030] Furthermore, when the unit board is processed in multiple regional blocks, if the pattern of the anti-weld opening is located at the boundary, the processing of the anti-weld opening pattern is completed in one go.

[0031] Furthermore, the PCB is a multilayer board, with the positioning holes at the four corners of the unit board serving as positioning targets in the first layer; and the target pattern processed from the first layer serving as alignment mark positioning points in the second layer.

[0032] Furthermore, the laser emitter power of the laser anti-welding window opening device is 10W-60W, the laser frequency is 80-1400KHZ, and the pulse width is 10-350ps.

[0033] Compared with the prior art, the PCB solder mask window manufacturing method provided by the present invention has the following advantages:

[0034] I. The PCB solder mask windowing method provided by this invention first involves routering the circuit board into unit boards, and then removing the solder mask layer using laser technology to form the desired windowing pattern. Because the expansion and contraction changes after routering into small unit boards are smaller compared to the entire board, the windowing position changes less. This invention involves routering the PCB requiring solder mask windowing into small units after applying solder mask silkscreen ink, then using a CCD positioning device to capture and align the board edges and / or internal Mark points. The expansion and contraction coefficient of the circuit board is calculated using an automatic expansion and contraction mode to simulate the actual windowing position. Then, laser technology is used to directly perform solder mask windowing. Compared to traditional solder mask exposure and development windowing technology, this method eliminates the pattern deviation caused by the superposition of tolerances in the exposure machine and film pattern transfer capabilities. By directly applying laser energy to the solder mask ink, the solder mask ink windowing is completed, offering the advantage of high precision.

[0035] II. The PCB solder mask window fabrication method provided by this invention adopts an automatic expansion and contraction zoning approach. At the positioning point, a multi-point alignment mode is used to collect data from different targets to form several region blocks. Each region block simulates the actual window opening position positioned according to the target, and the graphic scale of the window to be opened in that region block is adjusted according to the simulated window opening position. This allows the unit board to be processed in regions, further reducing the expansion and contraction changes of the circuit board and improving the processing accuracy of the graphics. During the region processing, if the solder mask window graphic is at the boundary, the processing of the solder mask window graphic is completed in one go, avoiding the problem of graphic seams affecting the solder mask window effect caused by two separate processing steps.

[0036] Third, the PCB solder mask window manufacturing method provided by the present invention can be used for multi-layer PCB designs. By controlling the laser energy, the penetration depth can be controlled, which can be used for precise removal of the solder mask in embedded designs and multi-layer structures with buried capacitors and resistors, thereby simplifying the manufacturing process.

[0037] Third, the PCB solder mask window manufacturing method provided by this invention can achieve precise control over the solder mask area, including the shape, size, and layout of the PCB circuitry, BGA, and PADs. The process of this invention can adapt to the ever-increasing demands for smaller tolerance dimensions and higher circuitry levels in PCB structures, i.e., the design requirements for high-density, miniaturized electronic devices.

[0038] IV. The PCB solder mask windowing method provided by this invention uses a combination of board edge position (four corners of unit board) and Mark point for alignment when laser solder mask windowing is used, and CCD alignment is also used for more accurate positioning.

[0039] V. The PCB solder mask windowing method provided by the present invention uses laser energy to remove the solder mask layer and complete the solder mask windowing, eliminating the step of developing chemical reaction, saving developing chemical and environmental treatment costs, and reducing the impact of chemicals on workers' health during the production process. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the laser anti-welding window opening device in this invention;

[0042] Figure 2 This is a diagram illustrating the effect of laser anti-welding window opening using the present invention. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below.

[0044] It should be noted that the descriptions of these embodiments are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] Please see Figure 1 This is a schematic diagram of the laser anti-welding window opening device in this invention. The laser anti-welding window opening device used in the process of this invention includes a laser emitter 2, a laser optical path 3, a scanning galvanometer 4, a scanning field mirror 5, a vacuum adsorption platform 6, a dust collection device 7, an X-direction moving axis 9, a Y-direction moving axis 8, a galvanometer Z-direction moving axis 10, and a CCD alignment device 11;

[0046] The laser emitter 2 transmits the generated laser beam to the scanning galvanometer 4 via the laser optical path 3. The scanning galvanometer 4 controls the position and direction of the laser beam. The scanning field mirror 5 is connected to the scanning galvanometer 4 and is used to adjust the laser focal length and laser beam size. The scanning galvanometer 4 consists of an XY optical scanning head, an electronic drive amplifier, and optical reflecting mirrors. The signal provided by the controller drives the optical scanning head through the drive amplifier circuit, thereby controlling the deflection of the laser beam in the XY plane. After passing through the scanning galvanometer field mirror, the laser beam is focused onto a single point (i.e., a spot), thereby increasing the energy density of the laser beam. This allows it to be used for cutting, marking, and other processing of various materials. Furthermore, when the direction of the incident laser beam changes, the field mirror maintains a spot with a constant relative size and energy density, enabling the laser beam to process points on different materials. The combination of the field mirror and the galvanometer, which can rapidly and accurately change the direction of the laser beam, enables high-speed and precision processing of materials.

[0047] The vacuum adsorption platform 6 is used to fix the circuit board to be processed, and the dust collection device 7 is located on one side of the vacuum adsorption platform 6 to remove dust from the surface of the circuit board.

[0048] The Y-axis moving axis 9 is used to adjust the motion trajectory of the scanning galvanometer and scanning field mirror in the horizontal Y direction; the X-axis moving axis 8 is used to adjust the motion trajectory of the vacuum adsorption platform in the horizontal X direction; the Z-axis moving axis 10 is used to adjust the motion trajectory of the scanning galvanometer and scanning field mirror in the Z direction; the CCD alignment device 11 is a coaxial telecentric CCD, coaxial with the scanning galvanometer 4, used for target point positioning.

[0049] After the customer's original data is processed by the engineering department, it is input into the controller. At the same time, the laser solder resist windowing device is activated to perform solder resist windowing on the circuit board to be processed on the vacuum adsorption platform.

[0050] The PCB solder resist windowing method of the present invention, using the laser solder resist windowing device, includes the following steps:

[0051] Step S1: The etched circuit board is processed according to the normal process of AOI → pre-soldering treatment → screen printing ink on both sides of the board → pre-baking → text → post-baking curing → PCB forming to obtain the unit board.

[0052] Step S2: Provide a laser anti-welding window opening device and a controller. Place the unit board that needs to be anti-welded and opened on the processing platform of the laser anti-welding window opening device. The structure of the laser anti-welding window opening device is as described above. In this embodiment, the processing platform corresponds to the vacuum adsorption platform of the laser anti-welding window opening device. The controller stores anti-welding window opening engineering data.

[0053] Step S3: Retrieve the engineering data stored in the controller. The CCD alignment device collects the positioning holes at the four corners of the unit board as positioning targets. Based on the collected positioning targets, the expansion and contraction coefficient of the circuit board is calculated through the automatic expansion and contraction mode, thereby simulating the actual window opening position. The graphic ratio of the window to be opened is adjusted according to the simulated window opening position so that the distance between the PAD formed by the window and the forming edge meets the tolerance requirements.

[0054] When setting the positioning targets, it is preferable to set multiple Mark points in the unit board to form a multi-point alignment mode. The unit board is divided into several area blocks according to the different positioning targets collected by the CCD alignment device. The actual window opening position of the area block is simulated by the positioning target of each area block. Then, the graphic ratio of the area block to be opened is adjusted according to the simulated window opening position. That is, the unit board is further subdivided into multiple area blocks for processing, which further improves the processing accuracy.

[0055] Specifically, when the number of positioning targets N satisfies 8 ≤ N ≤ 100, the unit board is divided into multiple regions and processed in blocks. Positioning targets include positioning holes at the four corners of the unit board and Mark points within the unit board. When the unit board is processed in multiple regions, if the weld resist window pattern is located at the boundary, the processing of that weld resist window pattern is completed in one go, avoiding the problem of pattern seams affecting the weld resist window effect caused by processing in two separate steps.

[0056] Step S4: Based on the simulated window opening position and the adjusted window opening graphic ratio, control the laser anti-welding window opening device to perform anti-welding window opening processing according to the preset path.

[0057] The laser emitter power of the laser anti-welding window opening device is 10W-60W, the laser frequency is 80-1400KHZ, and the pulse width is 10-350ps.

[0058] During processing, the initial windowing effect needs to be inspected. This mainly involves checking whether the dimensions of the laser-opened BGA and PAD meet the data requirements, whether the copper surface is damaged, whether the shape and dimensions are consistent with the data, and whether the edges are smooth and free of jagged edges. Figure 2 As shown, using the manufacturing process of this invention, the PAD window opening does not damage the copper surface, and the edges are smooth without jagged edges.

[0059] Using the manufacturing process of this invention, the tolerance accuracy of the distance between the PAD and the molding edge is controlled within ±1mil (25.4um), which improves the processing accuracy compared with the prior art.

[0060] The PCB solder mask window manufacturing method of the present invention can also be used for solder mask window manufacturing on multilayer PCBs. In the first layer, the positioning holes at the four corners of the unit board are used as positioning targets. Laser energy is used to remove the ink covering the PADs to be exposed, ensuring that each of the four edges of the unit board exposes two PADs. The distance from the PADs to the forming edge is measured according to engineering data. In the second layer, the target pattern processed in the first layer is used as alignment mark positioning points. Laser technology is used to remove the ink covering the pattern, exposing the solder mask window positions to be soldered. This process is repeated to complete the solder mask window manufacturing of multilayer PCBs.

[0061] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a solder mask window on a PCB, characterized in that, Includes the following steps: Step S1: The etched circuit board is processed according to the normal process of AOI → pre-soldering treatment → screen printing ink on both sides of the board → pre-baking → text → post-baking curing → PCB forming to obtain the unit board. Step S2: Provide a laser anti-welding window opening device and controller, place the unit board that needs to be anti-welding windowed on the processing platform of the laser anti-welding window opening device, the laser anti-welding window opening device includes a CCD alignment device; Step S3: Positioning holes are provided at the four corners of the unit board, and multiple Mark points are set inside the unit board; the engineering data stored in the controller is retrieved, and the CCD alignment device collects the positioning holes at the four corners of the unit board and multiple Mark points as positioning targets to form a multi-point alignment mode. The unit board is divided into several area blocks according to the collected positioning targets. The expansion and contraction coefficient of the circuit board is calculated through the automatic expansion and contraction mode. The actual window opening position of the area block is simulated through the positioning targets of each area block, and the graphic scale of the window to be opened in the area block is adjusted according to the simulated window opening position. Step S4: Based on the simulated window opening position and the adjusted window opening graphic ratio, control the laser anti-welding window opening device to perform anti-welding window opening processing according to the preset path.

2. The method for fabricating a PCB solder mask window according to claim 1, characterized in that, The laser anti-welding window opening device includes a laser emitter, a laser optical path, a scanning galvanometer, a scanning field mirror, a vacuum adsorption platform, a dust collection device, an X-axis moving axis, a Y-axis moving axis, a Z-axis moving axis for the galvanometer, and a CCD alignment device. The laser emitter transmits the generated laser beam to the scanning galvanometer through the laser optical path. The scanning galvanometer is used to control the position and direction of the laser beam. The scanning field mirror is connected to the scanning galvanometer and is used to adjust the laser focal length and the size of the laser beam. The vacuum adsorption platform is used to fix the circuit board to be processed, and the dust collection device is located on one side of the vacuum adsorption platform to remove dust from the surface of the circuit board. The Y-direction moving axis is used to adjust the motion trajectory of the scanning galvanometer and the scanning field mirror in the horizontal Y direction; the X-direction moving axis is used to adjust the motion trajectory of the vacuum adsorption platform in the horizontal X direction; and the Z-direction moving axis of the galvanometer is used to adjust the motion trajectory of the scanning galvanometer and the scanning field mirror in the Z direction. The CCD alignment device is coaxial with the scanning galvanometer and is used to grasp the positioning target to achieve positioning.

3. The method for fabricating a PCB solder mask window according to claim 1, characterized in that, When the number of positioning targets N satisfies 8≤N≤100, multiple region blocks are formed, and the number of positioning targets in each region block is ≥4.

4. The method for fabricating a PCB solder mask window according to claim 3, characterized in that, When the unit board is processed in multiple areas, if the anti-weld window pattern is at the boundary, the processing of the anti-weld window pattern is completed in one go.

5. The method for manufacturing a PCB solder mask window according to any one of claims 1-4, characterized in that, The PCB is a multilayer board. The first layer uses the positioning holes at the four corners of the unit board as positioning targets; the second layer uses the target pattern processed from the first layer as alignment mark positioning points.

6. The method for fabricating a PCB solder mask window according to claim 1, characterized in that, The laser emitter of the laser anti-welding window opening device has a power of 10W-60W, a laser frequency of 80-1400KHZ, and a pulse width of 10-350ps.

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