Method for improving manufacturing precision of printed circuit board and printed circuit board

Abstract

The invention discloses a method for improving the manufacturing precision of a printed circuit board and the printed circuit board. The method comprises the following steps: arranging and designing golden fingers of a plurality of golden finger plates in a jointed board in the same direction; equally dividing the designed total length of the golden fingers of the golden finger plate into a plurality of sections to obtain the designed length of each section; setting an expansion and shrinkage compensation value for each segment; and performing expansion and shrinkage compensation on the corresponding segments according to the expansion and shrinkage compensation values. According to the method, the golden fingers adopt the layout design in the same direction, pressing expansion and shrinkage control can be better carried out, meanwhile, the expansion and shrinkage compensation value is set for each segment and compensation is carried out, the size difference influence caused by the expansion and shrinkage difference of all areas of the board surface after the multilayer board is pressed can be effectively reduced, and therefore the manufacturing precision of the golden fingers is improved.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board manufacturing, and more specifically to a method for improving the manufacturing accuracy of a printed circuit board and a printed circuit board. Background Art

[0002] In the printed circuit board industry, LCD (Liquid Crystal Display) liquid crystal displays have the characteristics of small size, light weight, low radiation and low energy consumption, and have been widely used in various types of displays. With the continuous development of technology, the length of the gold fingers designed for LCD products is getting longer and longer. The length of some gold fingers reaches 624mm, and even reaches the working board length of the PCB board.

[0003] The normal design of LCD panels is a row of gold fingers on the hard board FR4 and a row of gold fingers on the soft FPC. Since the expansion and contraction of the soft FPC is more difficult to control, the normal design length of the FPC is very small and will not exceed 100mm, and 40-50mm is appropriate. Then use conductive glue to bond multiple FPCs and an LCD hard board together to play a conductive role, and the soft board can be bent at the same time. The tolerance requirements of the optical point to optical point of the gold finger are becoming more and more stringent, and the tolerance range of ±0.1mm needs to be achieved after mounting. The current traditional method cannot meet this tolerance requirement and can only achieve a tolerance of ±0.15mm. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a method for improving the manufacturing accuracy of a printed circuit board and a printed circuit board.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In one aspect, the present invention provides a method for improving the manufacturing accuracy of a printed circuit board, comprising:

[0007] The gold fingers of several gold finger boards in the puzzle are designed in the same direction;

[0008] Divide the overall length of the gold finger design of the gold finger board into multiple equal parts to obtain the design length of each segment;

[0009] Set expansion and contraction compensation value for each segment;

[0010] The corresponding segments are compensated for expansion and contraction according to the expansion and contraction compensation value.

[0011] Furthermore, a centering method is adopted to compensate for the expansion and contraction of each segment.

[0012] Furthermore, the step of setting the expansion / contraction compensation value for each segment includes:

[0013] Get the actual length of each segment after it is completed in the history generation process;

[0014] The expansion and contraction compensation value is calculated based on the design length of each segment and the actual length of the corresponding segment.

[0015] Furthermore, the calculation formula of the expansion and contraction compensation value is:

[0016] Expansion and contraction compensation value = (actual length of each segment - designed length of each segment) / designed length of each segment.

[0017] Furthermore, it also includes:

[0018] Determine the size of the PAD preset on the gold finger of the gold finger board;

[0019] Automatic dynamic compensation is performed according to the preset PAD size.

[0020] Furthermore, the automatic dynamic compensation according to the preset size of the PAD includes:

[0021] As the size of the preset PAD increases, the compensation amount is further increased on the basis of the conventional compensation amount.

[0022] Furthermore, it also includes:

[0023] When the width of the process edge of the panel reaches a specified width, and the positioning hole of the process edge reaches a specified hole diameter, the connection position of the process edge is designed to be outside the positioning hole.

[0024] Furthermore, the specified width is greater than 4 mm, and the specified aperture is 2 mm.

[0025] Furthermore, it also includes:

[0026] During the drilling process, all the guide holes of the gong plate of the panel are processed;

[0027] Set the pre-increase ratio for each gold finger board on the puzzle board;

[0028] When the panels are pressed together, the expansion and contraction differences of the corresponding gold finger panels are compensated according to the pre-expansion ratio.

[0029] On the other hand, the present invention further provides a printed circuit board, which is manufactured by the above-mentioned method for improving the manufacturing accuracy of the printed circuit board.

[0030] Compared with the prior art, the present invention has the following beneficial effects: a method for improving the manufacturing accuracy of printed circuit boards, comprising: designing the gold fingers of several gold finger boards in the panel in the same direction; dividing the overall length of the gold finger design of the gold finger board into multiple parts to obtain the design length of each segment; setting a shrinkage compensation value for each segment; and performing shrinkage compensation for the corresponding segment according to the shrinkage compensation value. The present invention can better control the shrinkage during pressing by designing the gold fingers in the same direction. At the same time, setting and compensating for the shrinkage compensation value for each segment can effectively reduce the size difference caused by the shrinkage difference in each area of ​​the board after pressing the multi-layer board, thereby improving the manufacturing accuracy of the gold finger.

[0031] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0033] Figure 1 A flowchart of a method for improving the manufacturing accuracy of a printed circuit board provided by a specific embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the arrangement direction of the gold fingers in the puzzle provided by a specific embodiment of the present invention;

[0035] Figure 3 A schematic diagram of automatic dynamic compensation of the size of a PAD provided by a specific embodiment of the present invention;

[0036] Figure 4 A schematic diagram of the design position of the process edge of the panel provided by a specific embodiment of the present invention;

[0037] Figure 5 A comparison diagram of the actual expansion and contraction of each gold finger plate on the puzzle board and the ideal state provided by the specific embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0040] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0041] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0042] like Figure 1 As shown, an embodiment of the present invention provides a method for improving the manufacturing accuracy of a printed circuit board, comprising the following steps: S10-S40.

[0043] S10, the gold fingers of several gold finger boards in the puzzle are all designed in the same direction.

[0044] The concepts of panelization and gold finger board are: in the printed circuit board (PCB) manufacturing industry, panelization is a way of combining multiple identical or similar small circuit boards (i.e. gold finger boards) on a larger board for production. Gold finger boards are circuit boards with gold finger structures. Gold fingers are the key parts of the circuit board for electrical connection with external devices. They are usually a row of golden conductive contacts, shaped like fingers.

[0045] When designing the panel, the position of each gold finger board should be reasonably planned according to the size of the panel, the number and size of the gold finger boards, so that the gold fingers can be neatly arranged in the same direction. Figure 2 As shown, the figure illustrates the arrangement direction of each gold finger plate in the puzzle board of this solution compared with the prior art.

[0046] During the PCB manufacturing process, lamination is an important process for bonding multi-layer circuit boards together by means of high temperature and high pressure. During the lamination process, the circuit board will expand and shrink to a certain extent. When the gold fingers are designed in the same direction, the distribution of the gold fingers is more regular and consistent, and the pressure and temperature distribution of each gold finger during the lamination process is more uniform, so that the expansion and contraction of the gold fingers can be predicted and controlled more accurately. In addition, during the etching process, the spray pressure and flow of the etching solution will affect the etching effect. When the gold fingers are designed in the same direction, the etching solution can act more evenly on each gold finger, reducing the gold finger size deviation and surface quality problems caused by uneven etching.

[0047] S20, dividing the overall length of the gold finger design of the gold finger board into multiple equal parts to obtain the design length of each segment.

[0048] Determining the number of segments requires a balance between compensation accuracy and operation complexity. The more segments there are, the more accurate the compensation for expansion and contraction will be, but the operation process will also be more complicated; if the number of segments is too small, the expansion and contraction differences at different positions of the gold finger may not be accurately reflected. Usually, the number of segments can be determined based on the length of the gold finger, the stability of the pressing process, and production experience.

[0049] Calculate the design length of each segment: Use the formula "design length of each segment = overall length of gold finger design ÷ number of segments" to calculate. In PCB design software, you can use the measurement tool to obtain the overall length of the gold finger design, and then calculate manually or use the script programming function of the software to automatically complete the calculation.

[0050] S30, setting an expansion / contraction compensation value for each segment.

[0051] During the production of printed circuit boards (PCBs), gold fingers will expand and shrink after processes such as lamination, and the expansion and shrinkage of different segments may be different. In order to ensure that the final size of the gold fingers meets the design requirements, it is necessary to set a suitable expansion and shrinkage compensation value for each segment to offset the size deviation caused by expansion and shrinkage.

[0052] In one embodiment, step S30 specifically includes the following steps: S301 - S302 .

[0053] S301, obtaining the actual length of each segment after it is completed in the history generation process.

[0054] Select representative samples from a large number of gold finger boards with the same or similar designs that have been produced in the past. The number of samples should be large enough to fully reflect the various situations in the production process. At the same time, the samples should cover different batches and different production time periods, because there may be slight differences in the raw material characteristics, production equipment status and process parameters of different batches.

[0055] For each sample's gold finger segment, the method of taking the average value of multiple measurements is adopted. Each segment is measured at least 5 times, and each measurement must ensure that the measurement position is accurate and the measurement angle is consistent. Record the data of each measurement, and then calculate the average value as the actual length of the segment.

[0056] S302, calculating the expansion and contraction compensation value according to the design length of each segment and the actual length of the corresponding segment.

[0057] After obtaining the actual length of each segment, the expansion and contraction compensation value is calculated by comparing it with the designed length. This compensation value is the key basis for the subsequent size adjustment of the gold finger segment.

[0058] The calculation formula of the expansion and contraction compensation value is: expansion and contraction compensation value = (actual length of each segment - designed length of each segment) / designed length of each segment. This formula can intuitively reflect the expansion and contraction ratio of each segment. A positive number indicates expansion, and a negative number indicates contraction.

[0059] Substitute the measured actual length of each segment and the predetermined design length into the formula for calculation. The calculation result can retain a certain number of decimal places, such as four decimal places, to ensure the accuracy of the compensation value. At the same time, the calculated expansion and contraction compensation values ​​are sorted and recorded, and a database is established to facilitate subsequent query and use.

[0060] For steps S301-S302, by obtaining the accurate historical actual length and calculating the expansion and contraction compensation value, compensation can be made for the specific expansion and contraction of each segment. In subsequent production, the design dimensions of the gold fingers are adjusted according to the compensation values, so that the actual dimensions of each segment of the gold fingers after process processing are closer to the design requirements, thereby significantly improving the manufacturing accuracy of the gold fingers. Improve product quality and stability: Improving the manufacturing accuracy of gold fingers helps to enhance the stability of their connection with external devices (such as slots). Gold fingers with precise dimensions can ensure good electrical contact, reduce interference and loss in signal transmission, improve the performance and reliability of electronic products, and reduce product failure rates.

[0061] S40, performing expansion and contraction compensation on the corresponding segment according to the expansion and contraction compensation value.

[0062] During the manufacturing process of printed circuit board (PCB) gold fingers, due to the influence of lamination and other processes, each segment of the gold finger will expand and shrink, resulting in a deviation between the actual size and the designed size. The expansion and contraction compensation value reflects the expansion and contraction ratio of each segment during the manufacturing process. By adjusting the design size of the segment according to this ratio, the actual size of each segment of the gold finger can be closer to the design requirements after the process, thereby improving the manufacturing accuracy of the gold finger.

[0063] The compensation method can be a centering method, specifically, taking the center of the segment as the reference, the size is adjusted towards both ends. For example, for a segment with a length of L, if the expansion and contraction compensation value is X%, then during the design, the two ends of the segment are extended towards the center or towards both ends by a length of L*(X% / 2).

[0064] By compensating the corresponding segments according to the expansion and contraction compensation value, the dimensional deviation of the gold finger caused by expansion and contraction during the manufacturing process can be effectively offset, so that the actual size of each segment of the gold finger is closer to the design size, thereby improving the overall dimensional accuracy of the gold finger. This is crucial to ensure a good connection between the gold finger and external devices (such as slots), and can reduce problems such as poor contact and unstable signal transmission caused by dimensional deviation.

[0065] In one embodiment, compensation may be performed using a unilateral compensation method.

[0066] In one embodiment, a method for improving the manufacturing accuracy of a printed circuit board further includes the following steps: S50-S60.

[0067] S50: Determine the size of the PAD preset on the gold finger of the gold finger board.

[0068] In a printed circuit board (PCB), a PAD (solder pad) is a key part of the gold finger of a gold finger board that is used to connect the pins of electronic components or to achieve electrical connection. It provides a welding position for the component pins, ensures that the current and signal can be stably transmitted between the gold finger and the external components, and is an important bridge to achieve electrical connection.

[0069] Different types of electronic devices and application scenarios have different requirements for the size of the PAD on the gold finger. Before determining the size of the PAD, you need to refer to relevant industry standards and design specifications, such as IPC (International Electronics Industry Connection Association) standards. These standards provide a general PAD size range and design guidance to ensure that the size of the PAD can meet the requirements of electrical performance, welding process and mechanical stability.

[0070] S60: Automatically perform dynamic compensation according to the preset size of the PAD.

[0071] During the manufacturing process of printed circuit boards (PCBs), the preset PAD (pad) size on the gold finger will be affected by a variety of factors and produce deviations, such as expansion and contraction caused by the lamination process, size changes during the etching process, etc. Automatic dynamic compensation means automatically adjusting the design size of the PAD based on the preset original size of the PAD and the influence of these process factors on the size, so as to ensure that the actual size of the final PAD meets the design requirements.

[0072] By collecting the production data of PCB gold finger PADs with the same or similar designs in past production, including the preset size, the actual size after production, and the corresponding process parameters (such as pressing temperature, pressure, etching time, etc.), the relationship between PAD size change and process parameters is found through statistics and analysis of these data, and a compensation model is established.

[0073] According to the compensation model, the corresponding compensation coefficient is determined for PADs of different size ranges. Generally speaking, as the preset PAD size increases, the compensation amount is further increased on the basis of the conventional compensation amount. The conventional compensation amount is generally 0.2%-0.5% of the PAD size. Figure 3 As shown, when the size of the PAD is less than 0.2 mm, the compensation is the conventional compensation amount plus 25 um.

[0074] Through automatic dynamic compensation, the dimensional deviation of PAD caused by various process factors during the manufacturing process can be effectively offset, so that the actual size of the final PAD is closer to the preset design size, thereby improving the manufacturing accuracy of the PAD size. This is crucial to ensure a good electrical connection between the gold finger and external devices, and can reduce problems such as poor contact and unstable signal transmission caused by PAD size deviation.

[0075] In one embodiment, a method for improving the manufacturing accuracy of a printed circuit board further includes the following steps: S70.

[0076] S70. When the width of the process edge of the panel reaches a specified width and the positioning hole of the process edge reaches a specified hole diameter, the connection position of the process edge is designed to be outside the positioning hole.

[0077] In the manufacture of printed circuit boards (PCBs), the process edge is an additional part added around the panel. It is not a functional part of the final product. It is mainly used to meet the needs of automated equipment operation and positioning during the production process, and to facilitate the flow and processing of PCBs between various processes.

[0078] The positioning holes on the process edge are holes used to accurately position the PCB during the production process. Automation equipment (such as placement machines, drilling machines, etc.) determine the position of the PCB through positioning holes to ensure the accuracy of processing.

[0079] The connection point is the connecting part between the process edge and the PCB unit. Its function is to maintain the connection between the PCB unit and the process edge during the production process, ensuring that the PCB can be processed stably in each process, and at the same time facilitate the separation of the PCB unit from the process edge after production is completed.

[0080] The specified width and the specified aperture are specific values ​​determined according to the PCB production process and equipment requirements. Generally speaking, the specified width is greater than 4mm, and the specified aperture is 2mm. When the width of the process edge reaches the specified width and the positioning hole reaches the specified aperture, certain structural strength and positioning accuracy requirements are met. At this time, the connection position of the process edge is designed to be outside the positioning hole. This design enables the process edge to better withstand external forces (such as equipment grabbing and conveying, etc.) during the production process, reduce the risk of board damage and broken edges, and ensure the integrity and stability of the PCB in each process. Figure 4 As shown, Figure 4 The left picture shows the layout of the existing process edge connection position, which is located inside the positioning hole. This design has the risk of board damage and edge breakage. Figure 4 The figure on the right in the middle shows the arrangement position of the connection position of the process edge of this solution, which is located outside the positioning hole.

[0081] In one embodiment, a method for improving the manufacturing accuracy of a printed circuit board further includes the following: S80-S100.

[0082] S80, process all the guide holes of the gong plate of the puzzle during the drilling data stage.

[0083] The function of the gong plate guide holes: The gong plate guide holes are mainly used to provide accurate positioning references for the CNC milling machine in the PCB forming process (gong plate), ensuring that the milling machine can accurately cut the shape of the PCB according to the design requirements.

[0084] Drilling data is a key design document in the early stage of PCB manufacturing. It determines the location, size, type and other information of each hole on the circuit board. At this stage, the processing planning of the gong board guide hole can be based on the original and accurate design data to avoid the influence of expansion and contraction caused by subsequent processes (such as pressing) on ​​the position accuracy of the guide hole.

[0085] In the PCB design software, the position and diameter of all the guide holes of the gong plate on the panel are accurately planned according to the design requirements, and a detailed drilling data file is generated. The drilling data file is imported into the drilling equipment, and appropriate drilling parameters such as drill speed and feed speed are set according to the diameter of the guide hole and the characteristics of the plate. The drilling equipment accurately drills all the guide holes of the gong plate on the panel according to the information in the drilling data. During the processing, it is necessary to ensure that the position accuracy and diameter tolerance of the drilling holes meet the design requirements.

[0086] The guide holes for the gong plate are processed in the drilling material stage, rather than in the gong plate material stage. This avoids the influence of subsequent process expansion and contraction on the position of the guide holes, and enables the CNC milling machine to position according to the precise guide holes during the gong process, thereby improving the cutting accuracy of the PCB shape and reducing the shape deviation and dimensional error caused by inaccurate positioning.

[0087] S90. Set the pre-increase ratio for each gold finger board on the puzzle board.

[0088] During the PCB lamination process, due to the differences in pressure, temperature and other factors on the gold finger boards at different positions of the panel, each gold finger board will expand and shrink to different degrees. Setting a pre-expansion ratio for each gold finger board is to compensate for this expansion and contraction difference in advance, so that the actual size of the gold finger board after lamination is closer to the design requirements.

[0089] By reviewing the PCB production process with the same or similar design, materials and processes in the past, the size data of each gold finger board before and after lamination is collected, and the expansion and contraction rules and degrees of gold finger boards at different positions are analyzed. Based on historical data and experimental test results, the average expansion and contraction ratio of each gold finger board is calculated as the pre-expansion ratio of the gold finger board.

[0090] S100. When the panels are pressed together, the expansion and contraction differences of the corresponding gold finger panels are compensated according to the pre-expansion ratio.

[0091] like Figure 5 As shown, Figure 5 The figure shows the actual expansion and contraction of each gold finger board on the panel compared with the ideal state. By compensating according to the set pre-expansion ratio, the design is closer to the ideal state.

[0092] During the panel lamination process, the design dimensions of the gold finger board are adjusted accordingly according to the pre-expansion ratio previously set for each gold finger board. If the pre-expansion ratio is a positive value (expansion), the design dimension is appropriately increased; if the pre-expansion ratio is a negative value (contraction), the design dimension is appropriately reduced to offset the actual expansion and contraction during the lamination process. Such a design can further improve the dimensional accuracy of the gold finger board, so that the deviation between the actual size and the design size of the gold finger board after lamination is controlled within a very small range. At the same time, it reduces the problem of unqualified dimensions caused by differences in expansion and contraction, reduces the defective rate of products, and improves production efficiency and economic benefits.

[0093] The embodiment of the present invention further provides a printed circuit board, which is manufactured by using the above-mentioned method for improving the manufacturing accuracy of the printed circuit board.

[0094] The printed circuit board provided by the present invention is manufactured by the method for improving the manufacturing accuracy of a printed circuit board according to any of the above embodiments, and therefore has all the beneficial effects of the method for improving the manufacturing accuracy of a printed circuit board, which will not be described in detail herein.

[0095] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for improving the manufacturing accuracy of a printed circuit board, characterized in that: include: The gold fingers of several gold finger boards in the puzzle are designed in the same direction; Divide the overall length of the gold finger design of the gold finger board into multiple equal parts to obtain the design length of each segment; Set expansion and contraction compensation value for each segment; The corresponding segments are compensated for expansion and contraction according to the expansion and contraction compensation value.

2. A method for improving the manufacturing accuracy of a printed circuit board according to claim 1, characterized in that: The expansion and contraction compensation is carried out for each section in a divided manner.

3. A method for improving the manufacturing accuracy of a printed circuit board according to claim 1, characterized in that: The step of setting the expansion / contraction compensation value for each segment includes: Get the actual length of each segment after it is completed in the history generation process; The expansion and contraction compensation value is calculated based on the design length of each segment and the actual length of the corresponding segment.

4. A method for improving the manufacturing accuracy of a printed circuit board according to claim 3, characterized in that: The calculation formula for the expansion and contraction compensation value is: Expansion and contraction compensation value = (actual length of each segment - designed length of each segment) / designed length of each segment.

5. A method for improving the manufacturing accuracy of a printed circuit board according to claim 1, characterized in that: Also includes: Determine the size of the PAD preset on the gold finger of the gold finger board; Automatic dynamic compensation is performed according to the preset PAD size.

6. A method for improving the manufacturing accuracy of a printed circuit board according to claim 5, characterized in that: The automatic dynamic compensation according to the preset PAD size includes: As the size of the preset PAD increases, the compensation amount is further increased on the basis of the conventional compensation amount.

7. A method for improving the manufacturing accuracy of a printed circuit board according to claim 1, characterized in that: Also includes: When the width of the process edge of the panel reaches a specified width, and the positioning hole of the process edge reaches a specified hole diameter, the connection position of the process edge is designed to be outside the positioning hole.

8. A method for improving the manufacturing accuracy of a printed circuit board according to claim 7, characterized in that: The specified width is greater than 4 mm, and the specified aperture is 2 mm.

9. A method for improving the manufacturing accuracy of a printed circuit board according to claim 1, characterized in that: Also includes: During the drilling process, all the guide holes of the gong plate of the panel are processed; Set the pre-increase ratio for each gold finger board on the puzzle board; When the panels are pressed together, the expansion and contraction differences of the corresponding gold finger panels are compensated according to the pre-expansion ratio.

10. A printed circuit board, characterized in that: The printed circuit board is manufactured by the method for improving the manufacturing accuracy of a printed circuit board according to any one of claims 1 to 9.

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