A method for manufacturing large-size PCB boards

Abstract

This invention relates to the field of PCB manufacturing technology, and more particularly to a method for manufacturing large-size PCBs, comprising: cutting a large-size substrate into several core boards conforming to the dimensions of a PCB; drilling several positioning holes with a first pre-expansion / shrinkage amount in the core boards; determining the position range of the circuit pattern on the core boards according to the positioning holes; determining the range of the rivet hole circuit pattern that coincides with the range of the positioning hole circuit pattern according to the range of the positioning hole circuit pattern; drilling several rivet holes with a second pre-expansion / shrinkage amount in the range of the rivet hole circuit pattern, wherein the first pre-expansion / shrinkage amount is the sum of the etching expansion / shrinkage amount and the pressing expansion / shrinkage amount during the process of cutting and laminating the core board; and the second pre-expansion / shrinkage amount is the etching expansion / shrinkage amount during the process of cutting and etching the core board. This invention can solve the problems of inconsistent expansion / shrinkage coefficients of core boards with different thicknesses or different copper thicknesses due to expansion / shrinkage during the manufacturing of large-size PCBs, and the problems of rivets not fitting or laminating layers being misaligned during lamination and riveting.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, and more particularly to a method for manufacturing large-size PCB boards. Background Technology

[0002] Printed circuit boards (PCBs), also known as circuit boards or printed circuit boards, are crucial components in the electronics industry. They serve as the support for electronic components and the carrier for electrical connections. The size of a PCB depends on the processing capabilities of the equipment. Most equipment can process 610*760mm boards, but clients often have demands for larger boards. However, conventional processes and methods cannot produce large-size boards, primarily due to limitations in the lamination process, specifically the capabilities of the OPE (Operating Pebble Erector) and the hot melt machine. The OPE punch uses a 1:1 coefficient to punch rivet holes from the board center, preventing issues like rivets not fitting into core boards of varying thicknesses. However, for large-size boards, the OPE's limitations necessitate drilling rigs to drill rivet holes. The inconsistent expansion and contraction coefficients of core boards with different thicknesses or copper thicknesses can lead to rivet misalignment or misalignment during lamination. Therefore, we propose a method for manufacturing large-size PCBs. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for manufacturing a large-size PCB board. This invention can solve the problems of inconsistent expansion and contraction coefficients of core boards with different thicknesses or copper thicknesses due to expansion and contraction during the manufacturing of large-size PCBs, as well as the inability to fit rivets or misalignment of the lamination layer during pressing and riveting.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for manufacturing a large-size PCB board includes:

[0006] Several positioning holes containing the first pre-expansion and contraction amount are drilled in the core board, and the circuit pattern range is determined according to the positioning holes;

[0007] The rivet hole circuit pattern range that overlaps with the circuit pattern range of the positioning hole is determined according to the circuit pattern range of the positioning hole. Several rivet holes containing the second pre-expansion and contraction amount are drilled within the circuit pattern range of the rivet hole.

[0008] The first pre-expansion / contraction amount is the sum of the etching expansion / contraction amount and the pressing expansion / contraction amount during the process from blanking to pressing of the core board, and the second pre-expansion / contraction amount is the etching expansion / contraction amount during the process from blanking to etching of the core board.

[0009] Taking into account the expansion and contraction factors, the expansion and contraction coefficients of the rivet holes and the pattern are designed differently and drilled separately. This solves the problem of inconsistent expansion and contraction coefficients of core boards with different thicknesses or different copper thicknesses caused by expansion and contraction when manufacturing large-size PCBs, as well as the problem of rivets not fitting or lamination layers being misaligned during lamination and riveting.

[0010] Preferably, the expression for the etching expansion / contraction is: SK = (LS) / L;

[0011] Where SK is the etching expansion / contraction amount, L is the theoretical distance between the two selected positioning holes, and S is the actual distance between the two selected positioning holes after etching.

[0012] The expression for the compression expansion and contraction is: YH = (SD) / L;

[0013] Where YH is the compression expansion and contraction amount, and D is the actual distance between the two positioning holes selected after compression.

[0014] Considering the expansion and contraction factors, the expansion and contraction coefficients of the rivet holes are designed differently from those of the pattern, and the holes are drilled separately. By setting up positioning holes and rivet holes with pre-expansion and contraction, the influence of positioning holes and rivet holes on the lamination and etching process can be offset. This can solve the problems of inconsistent expansion and contraction coefficients of core boards with different thicknesses or different copper thicknesses caused by expansion and contraction when manufacturing large-size PCBs, as well as the problems of rivets not being able to be fitted or lamination layers being misaligned during lamination and riveting.

[0015] Preferably, after drilling a plurality of rivet holes containing a second pre-expansion amount within the rivet hole pattern area, the process includes:

[0016] Obtain the core board with completed drilling, arrange the core boards in the order of layers, add a prepreg between two adjacent core boards, and press the core boards and the prepreg into a core board with a sequential structure using a press.

[0017] When a multilayer PCB is composed of different internal layers of sheets, a hardening film is used to clamp the layers and press them tightly together. This helps ensure the flatness of the PCB and the stability of the overall structure. During operation, the PCB generates heat, and the hardening film helps improve its heat dissipation. By contacting the PCB, the hardening film effectively absorbs and disperses heat on the board, reducing component temperature rise, maintaining circuit stability, and enhancing the PCB's heat dissipation performance.

[0018] Preferably, after pressing the core board and PP into a core board with a sequential structure using a press, the process includes:

[0019] Drill through holes in the core board and clean the burrs from the openings of the positioning holes, rivet holes, and through holes;

[0020] After removing the burrs, the via is copper plated.

[0021] Burrs at the orifice can weaken the signal transmission strength, reduce the transmission distance, and even cause signal interference. Removing burrs can ensure the stability and reliability of signal transmission;

[0022] Copper has excellent corrosion resistance. Through copper plating technology, a dense copper film can be formed inside the holes, effectively protecting the positioning holes and rivet holes from environmental corrosion. This helps prevent the positioning holes and rivet holes from being corroded by environmental factors such as humidity and corrosive gases, thereby enhancing the overall durability of the PCB.

[0023] Preferably, after removing the burrs, the process of copper plating the positioning holes and rivet holes includes:

[0024] The surface of the core board is coated with copper to obtain a core board covered with a copper layer;

[0025] The surface of the copper layer is processed to obtain the circuit pattern, and the copper layer is etched to remove unwanted copper foil.

[0026] Copper is an excellent conductive material. Plating copper can significantly increase the conductivity and current flow of the core board, thereby improving the performance and reliability of the circuit. Plating copper can also enhance the corrosion resistance and mechanical strength of the core board, enabling the circuit board to maintain stable and reliable performance under various environmental conditions.

[0027] Preferably, the process of performing a pattern-making process on the surface of the copper layer to obtain a circuit pattern, and then etching the copper layer to remove unwanted copper foil, includes:

[0028] The core board is subjected to solder resist treatment, and the surface of the circuit pattern is gold plated.

[0029] The core board after gold plating is subjected to performance testing and visual inspection.

[0030] Gold has excellent electrical conductivity; plating gold onto PCB circuit patterns can significantly improve the conductivity of the circuit board. This not only helps reduce line impedance but also improves signal transmission efficiency, ensuring the stability and reliability of electronic devices during high-speed operation. The gold plating layer forms a protective film on the PCB surface, which has good corrosion resistance and oxidation resistance. It can prevent the circuit board from being corroded by environmental factors such as air, moisture, and chemicals, thereby extending the PCB's lifespan.

[0031] Preferably, the performance tests include insulation resistance testing, welding testing, and signal testing.

[0032] Performance testing allows for a comprehensive evaluation of the electrical, physical, and reliability properties of a PCB, ensuring that it meets design requirements and relevant standards. This helps to identify and fix potential problems in a timely manner, thereby improving the overall quality of the product.

[0033] Preferably, the diameter of the positioning hole and the rivet hole is 2mm.

[0034] When the diameter of the positioning hole is 2mm, precise alignment can be achieved, allowing the core board to fit accurately and improving the electrical performance and reliability of the circuit board. If the rivet diameter is too large, it will be difficult to form the upsetting head and it will easily deform the board. If the diameter is too small, the rivet strength will be insufficient. The selection of the rivet diameter depends on the size of the hole of the riveting part. Generally, the hole diameter is 1-2mm. If it is larger than 2mm, it may loosen. However, within a reasonable range, positioning holes and rivet holes of different diameters can be used as alternatives in this application.

[0035] Preferably, before drilling a plurality of positioning holes containing a first pre-expansion amount in the core board, the method further includes:

[0036] The large substrate is cut into several core boards of the same size.

[0037] Preferably, the length of the core board is between 760mm and 1245mm.

[0038] When the size is between 760mm and 1245mm, it is considered a large-size PCB board. PCB boards of different sizes derived from this application can all be used as alternatives to this application.

[0039] Larger PCBs allow designers to separate circuit components and wiring space more widely, helping to reduce signal interference and noise. This layout is especially important for applications requiring high-precision or high-speed signals, as it significantly improves the accuracy and stability of signal transmission.

[0040] Larger PCBs allow for more space between components, making assembly easier. Larger PCBs also mean easier fault identification and location, thus reducing maintenance costs and downtime.

[0041] The beneficial effects of this invention are as follows:

[0042] This invention drills positioning holes with a first pre-expansion / contraction amount on the edge of the core board. The positioning holes determine the range of circuit pattern positions, and the corresponding rivet hole circuit pattern positions are determined based on this range. Several rivet holes with a second pre-expansion / contraction amount are drilled within the rivet hole circuit pattern range. Considering expansion and contraction factors, this application differentiates the expansion and contraction coefficients of the rivet holes from those of the pattern, drilling them separately. The first pre-expansion / contraction amount is the sum of the etching expansion and contraction amount and the pressing expansion and contraction amount during the core board's process from blanking to etching. The second pre-expansion / contraction amount is the change in etching expansion and contraction during the core board's process from blanking to etching. This invention solves the problems of inconsistent expansion and contraction coefficients of core boards with different thicknesses or copper thicknesses, and the inability to fit rivets or misalignment of the pressing layer during pressing and riveting, which are caused by expansion and contraction factors when manufacturing large-size PCBs. Attached Figure Description

[0043] Figure 1 This is a flowchart of a method for manufacturing large-size PCB boards in a specific embodiment of the present invention;

[0044] Figure 2 This is a design drawing used in the specific implementation of the present invention for the fabrication of large-size PCB boards;

[0045] Figure 3 This is a standard manufacturing design drawing for large-size PCB boards with inconsistent core board thickness and copper thickness in a specific implementation of the present invention;

[0046] Figure 4 This is a standard manufacturing design drawing for large-size PCB boards with consistent core board thickness and copper thickness in a specific implementation of the present invention;

[0047] Figure 5 This is a diagram showing the positional distribution of the positioning holes and rivet holes in a specific embodiment of the present invention.

[0048] Attached diagram markings: 1. Positioning hole; 2. Rivet hole. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Please see Figures 1-5 As shown, this invention relates to a method for manufacturing a large-size PCB board.

[0051] Example 1

[0052] refer to Figure 1As shown, a method for manufacturing a large-size PCB board includes:

[0053] The large substrate is cut into several core boards that conform to the size of the PCB board, and the core board size is between 760mm and 1245mm.

[0054] A plurality of positioning holes 1 containing a first pre-expansion and contraction amount are drilled in the core board, and the position range of the circuit pattern is determined according to the positioning holes 1;

[0055] Based on the location range of the positioning hole 1, determine the rivet hole 2 line pattern range that coincides with the location range of the positioning hole 1 line pattern. Based on the location range of the rivet hole 2 line pattern, drill a plurality of rivet holes 2 containing a second pre-expansion and contraction amount in the core plate.

[0056] This application solves the problem that the expansion and contraction coefficients of core boards with different thicknesses or different copper thicknesses are inconsistent due to the influence of expansion and contraction, which leads to the inability to fit the rivet or the misalignment of the pressing layer during the pressing and riveting process. By aligning the circuit pattern position range of the positioning hole 1 and the rivet hole 2, this application can solve the problem that the rivet cannot be fitted or the pressing layer is misaligned during the pressing and riveting process.

[0057] The first pre-expansion / contraction amount is the sum of the etching expansion / contraction amount and the pressing expansion / contraction amount during the process from cutting to etching of the core board, and the second pre-expansion / contraction amount is the change in etching expansion / contraction amount during the process from cutting to etching of the core board.

[0058] The expression for the etching expansion / contraction is: SK = (LS) / L;

[0059] Where SK is the etching expansion and contraction amount, L is the theoretical distance between the two positioning holes 1, and S is the actual distance between the two positioning holes 1 after etching;

[0060] The expression for the compression expansion and contraction is: YH = (SD) / L;

[0061] Where YH is the compression expansion and contraction amount, and D is the actual distance between the two positioning holes 1 after compression.

[0062] For example, with TU865 material, the expansion and contraction change SK after etching is a contraction of 0.05%, and the expansion and contraction change YH after pressing is a contraction of 0.07%. Therefore, the first pre-expansion and contraction amount of the positioning hole is 0.05 + 0.07 = 0.12%, and the second pre-expansion and contraction amount of the rivet hole is 0.05%. Thus, the pre-expansion and contraction coefficient of the positioning hole is 1.0012, while the pre-expansion and contraction coefficient of the rivet hole is 1.0005.

[0063] In practice, there can be multiple positioning holes 1 on the core board. Theoretically, any two positioning holes 1 can be selected, as long as the two positioning holes 1 measured before and after are the same.

[0064] refer to Figure 5As shown, in this embodiment, there are four positioning holes, symmetrically located at the four corners of the PCB board. This method can form a multi-point, surface-based positioning method, which makes the positioning more accurate. Because the four corners serve as fixed points, the position of the PCB can be kept stable during processing, testing, and assembly, reducing offset and errors.

[0065] In terms of theoretical distance selection, only positioning hole 1 can be selected, not rivet hole 2, because rivet hole 2 has different expansion and contraction. During pressing, the rivet in rivet hole 2 will not change with the expansion and contraction of the core board after the rivet is fixed. That is, rivet hole 2 only has the expansion and contraction amount during etching, and there is no expansion and contraction amount during pressing. However, positioning hole 1 will have expansion and contraction during etching and pressing. During etching, the expansion and contraction changes of positioning hole 1 and rivet hole 2 are consistent.

[0066] In this embodiment, the PCB board generated by this method is generally 1000mm in size, which is a large-size PCB board. Compared with the traditional small-size 760mm PCB board, the PCB board of this application can carry more electronic components and complex circuit layout, thereby achieving a higher degree of integration.

[0067] A 1000mm PCB allows designers to separate circuit components and wiring space further apart, helping to reduce signal interference and noise. This layout is especially important for applications that require high precision or high-speed signals, as it can significantly improve the accuracy and stability of signal transmission.

[0068] A 1000mm PCB increases the space between components, making the assembly process easier. A larger PCB also means that faults are easier to identify and locate, thereby reducing maintenance costs and downtime.

[0069] refer to Figures 2-3 As shown, this method takes into account the expansion and contraction factors compared with traditional technology. In the case of inconsistent core board thickness, the expansion and contraction coefficients of the rivet holes 2 and the pattern are designed differently and drilled separately.

[0070] Traditional methods, when dealing with inconsistent core board thickness or copper thickness, do not take into account the expansion and contraction coefficients of the rivet hole 2 and the pattern. The expansion and contraction amounts of the positioning hole 1 and the rivet hole 2 are consistent. After etching, the rivet hole 2 becomes misaligned. The misalignment of the rivet hole 2 makes it difficult to fit the rivet during pressing and riveting. All core boards have different changes, resulting in layer misalignment after pressing.

[0071] This solution takes into account expansion and contraction factors. In the case of inconsistent core board thickness, rivet holes 2 with a second pre-expansion and contraction amount are set. The second pre-expansion and contraction amount offsets the actual expansion and contraction changes of rivet holes 2 after core board etching, so that rivet holes 2 will not be misaligned. The positioning holes 1 with the first pre-expansion and contraction amount offset the actual expansion and contraction of the core board pattern after pressing, so that the pressing layer will not be misaligned. By setting the positioning holes 1 with the first pre-expansion and contraction amount and the rivet holes 2 with the second pre-expansion and contraction amount, the problem of rivets not being able to be fitted or the pressing layer being misaligned during core board pressing and riveting is prevented.

[0072] refer to Figure 4 As shown, for cases where the core board thickness is uniform, the conventional method is as follows: when drilling holes in the core board, the positioning hole 1 and the rivet hole 2 expand and contract with the core board strip. After the core board undergoes pressing and etching processes, the expansion and contraction of all core boards are consistent, and the rivet holes 2 are aligned, so there will be no problem of the rivet not fitting properly during riveting or layer misalignment during pressing.

[0073] In traditional methods, the expansion and contraction amounts of positioning hole 1 and rivet hole 2 are consistent. However, in this application, the pre-expansion and contraction amount of positioning hole 1 is the sum of the etching expansion and contraction amount and the pressing expansion and contraction amount during the core board process from blanking to etching, so that the expansion and contraction ratio of all core board patterns after pressing is 1:1. The pre-expansion and contraction amount of rivet hole 2 is the change in etching expansion and contraction amount during the core board process from blanking to etching, so that the expansion and contraction ratio of rivet hole 2 after etching is 1:1. Figure 2 The difference in expansion and contraction after etching refers to the difference in expansion and contraction of the core board pattern. After lamination, the expansion and contraction of the core board pattern is 1:1. After etching, the expansion and contraction of rivet hole 2 is 1:1.

[0074] The size range of this method is for PNL length of 1000mm, while the existing size is mostly around 610*760mm. This method can solve the problems of inconsistent expansion and contraction coefficients of core boards with different thicknesses or different copper thicknesses due to expansion and contraction when manufacturing large-size PCBs, as well as the problems of rivets not fitting or lamination layers being misaligned during lamination and riveting.

[0075] The diameter of the positioning hole 1 and the rivet hole 2 in this application is 2mm. The selection of the rivet diameter is mainly determined by the thickness of the sheet metal and the riveting method. If the rivet diameter is too large, it will be difficult to form the upsetting head and it will easily deform the sheet metal; if the diameter is too small, the rivet strength will be insufficient. The selection of the rivet diameter depends on the size of the hole diameter of the riveted parts. Generally, the hole diameter is 1-2mm. If it is larger than 2mm, it may loosen.

[0076] Obtain standard core boards with completed drilling, arrange the standard core boards according to the layer order, and add prepreg (PP) between two adjacent core boards. The prepreg (PP) plays a key adhesive role in the production of multilayer boards. After the treated fiberglass cloth is impregnated with resin, it is heat-treated (pre-baked) to bring the resin into the B stage, forming a thin sheet material. This material softens under heat and pressure, fills the blank areas between layers, and then cools and reacts to cure, thereby tightly bonding the layers in the multilayer board together.

[0077] The stacked PCB boards are placed in a hot press or similar equipment and heated to a high temperature, the specific temperature of which depends on the PCB material and design requirements. High pressure is applied through a hydraulic system, the specific pressure of which also depends on the PCB material and design requirements. The high temperature and high pressure melt the adhesive between the conductive and insulating layers and firmly bond them together. The core board and PP are then pressed together by the press to form a core board with a sequential structure. After heating and pressurization, the PCB boards are removed from the hot press and cured during the cooling process. This allows the adhesive to harden again and ensures the structural stability of the PCB boards.

[0078] Preferably, the gelation time is typically 180 seconds, which represents the curing speed of the prepreg PP under specific conditions.

[0079] The adhesive content is generally 50%, which indicates the resin content in the prepreg (PP) sheet, affecting its bonding and insulation properties.

[0080] The flowability is typically 24%, which indicates the fluidity of the prepreg PP under heat and pressure, affecting its ability to fill the gaps between layers.

[0081] In some other embodiments, the gelation time, gel content, and flowability may include any values ​​within a reasonable range, and may be used as alternatives to this application.

[0082] Place the fabricated PCB board on the drilling machine, ensuring the board surface is flat and free of impurities. Select the appropriate drill bit according to the drilling specifications and install it on the drilling machine. Adjust the drilling machine parameters, such as spindle speed and feed rate, to accommodate PCB boards of different materials and thicknesses.

[0083] Start the drilling machine and, according to the requirements of the drilling file, automatically or manually control the drill bit to drill holes on the PCB board. During the drilling process, it is necessary to ensure that the position, depth, angle and other parameters of the drill bit are accurate to avoid damage to the PCB board or affecting subsequent processes.

[0084] Drill holes in the core board and remove burrs from the hole openings;

[0085] After removing the burrs, copper plating is performed inside the hole. The hole walls are metallized by chemical plating or electroplating to allow the pins of electronic components to connect to the internal circuitry.

[0086] After copper plating inside the holes, the PCB and copper foil are placed together in an electrolytic tank. Current is injected into the tank, causing copper ions to undergo a redox reaction in the electrolyte, depositing a copper layer on the substrate surface. Before copper plating on the PCB, degreasing is required: this step removes oil, fingerprints, oxides, and dust from the board surface and holes. Alkaline degreasing adjusts the charge on the hole walls, changing it from negative to positive, thus facilitating the adsorption of colloidal palladium in subsequent processes. Next is micro-etching: this step further removes oxides from the board surface and roughens the surface to ensure good adhesion between the subsequent copper plating layer and the underlying copper of the substrate. After copper plating, the substrate is used for circuit fabrication, which includes the following steps:

[0087] I. Graphic Design and Preparation

[0088] Circuit design: Based on product requirements and functional specifications, use circuit design software (such as Cadence, Altium Designer, etc.) to design the circuit, including layout and routing.

[0089] Graphical output: Convert the designed circuit diagram into the format required for production, usually Gerber files or other CAD data formats.

[0090] II. Transferring Graphics to Board Material

[0091] Screen protector application method:

[0092] Prepare the dry film: Select a dry film suitable for the board material and circuit design, ensuring its adhesion and etch resistance.

[0093] Film application: Using a film application machine or manually, apply the dry film evenly to the copper surface of the board.

[0094] Exposure: The board with the film applied is placed in an exposure machine and irradiated with ultraviolet light to cause a chemical reaction in the photosensitive material of the circuit pattern.

[0095] Development: The dry film of the unexposed areas is removed using a developer, exposing the copper surface that needs to be etched.

[0096] Inkjet printing:

[0097] Prepare the inkjet printer: Use a specialized inkjet printer and conductive ink.

[0098] Printing: The circuit pattern is printed directly onto the copper surface of the board, and the conductive material in the ink will form the circuit pattern.

[0099] Curing: The ink is cured by heating or UV light irradiation, which enhances adhesion and conductivity.

[0100] III. Etching and Film Removal

[0101] Etching:

[0102] Prepare the etching solution: Select a suitable etching solution to ensure its etching rate and uniformity on copper.

[0103] Etching process: The board with the film or printed pattern is placed in the etching machine, and the etching solution etches away the unprotected copper layer to form the circuit pattern.

[0104] Post-etching cleaning: After etching is completed, use cleaning agent and water to thoroughly clean the etching solution and residues from the surface of the plate.

[0105] Remove the membrane:

[0106] For boards manufactured using the dry film process, the remaining dry film needs to be removed after etching. This is typically done using a stripping solution or mechanical peeling.

[0107] For inkjet printing, if the ink has already cured and no further processing is required, this step can be skipped.

[0108] IV. Follow-up processing and inspection

[0109] Desoldering: If a layer of solder was used for protection during the circuit manufacturing process, the excess solder layer needs to be removed with desoldering solution.

[0110] Circuit inspection: Use a magnifying glass or microscope to carefully inspect the etched circuit to ensure that the circuit is intact and free of open circuits or short circuits.

[0111] Cleaning and drying: Perform a final cleaning of the board to ensure there are no residues on the surface, and then dry it for subsequent processing.

[0112] Solder mask treatment process:

[0113] Prepare solder resist ink: Select a suitable solder resist ink according to design requirements. This ink has specific adhesion and etching resistance to protect the parts of the circuit board that do not need to be soldered.

[0114] Applying solder resist ink: Using specialized coating equipment or manually, evenly apply the solder resist ink to the surface of the circuit board. This process must ensure that the ink layer is of uniform thickness and free of bubbles and impurities.

[0115] Pre-baking: The applied solder resist ink is pre-baked by heating to dry and cure it. The pre-baking temperature and time need to be adjusted according to the characteristics of the ink and the requirements of the circuit board.

[0116] Exposure: The pre-baked circuit board is exposed using an exposure machine. During the exposure process, the ink on the parts that need to be soldered is cured by precisely controlling the light source and exposure time, while the parts that do not need to be soldered remain uncured.

[0117] Developing: The exposed circuit board is immersed in a developing solution, where a chemical reaction removes the uncured solder resist, exposing the metal parts that need to be soldered. The developing process requires strict control of time and temperature to avoid damaging the circuit board.

[0118] Post-processing: The developed circuit board is cleaned and dried to remove residual developer and impurities. Then, a quality inspection is performed to ensure the integrity and accuracy of the solder mask layer.

[0119] Gold plating process:

[0120] Surface Cleaning and Preparation: Before gold plating begins, the surface of the circuit board needs to be thoroughly cleaned to remove oil, oxides, and other impurities. This can be achieved by using cleaning agents or methods such as acid or alkaline washing.

[0121] Activation treatment: The circuit board surface is treated with an activator to increase its ability to adsorb metal ions. This helps improve the adhesion and uniformity of the gold layer during the subsequent gold plating process.

[0122] Gold plating: The treated circuit board is immersed in a gold plating solution, where gold ions are reduced to a gold layer on the metal surface of the circuit board using an electrochemical method. This process requires control of parameters such as current, voltage, and time to ensure that the thickness and quality of the gold layer meet the requirements.

[0123] Post-treatment and cleaning: After gold plating, the circuit board needs post-treatment, such as cleaning and drying. This helps remove residual gold plating solution and other impurities, while ensuring the stability and corrosion resistance of the gold layer.

[0124] Example 2

[0125] Preferably, at least two positioning holes 1 are provided on the diagonal of the core board. This helps to ensure the standardization and uniformity of PCB design. If the PCB dimensions are the same for different single boards of the same product, the positions of the positioning holes 1 must also be consistent. This helps to improve production efficiency and product quality.

[0126] In some other embodiments, the number and location of the positioning holes should be determined based on the actual needs of the PCB. For example, for PCBs requiring high-precision machining, it may be necessary to increase the number of positioning holes to improve stability, while for cost-sensitive applications, it is necessary to control the number of positioning holes as much as possible while ensuring accuracy.

[0127] refer to Figure 5As shown, in this embodiment, a large-sized substrate is cut into several core boards that conform to the size of a PCB board, with the size being between 760mm and 1245mm.

[0128] The positioning holes 1 are set at the four corners of the core board. Positioning holes 1 containing a first expansion and contraction amount are drilled at the four corners of the core board. The positioning holes 1 determine the position range of the circuit pattern. The position range of the circuit pattern determined by the positioning holes 1 is used as the position range of the rivet hole 2 circuit pattern to set the rivet hole 2. The rivet hole 2 containing a second expansion and contraction amount is provided along the edge of the board where the positioning holes 1 are located. The rivet hole 2 and the positioning holes 1 are symmetrically arranged on both sides of the center point of the positioning holes 1.

[0129] When the positioning holes 1 are located at the four corners or diagonals of the core board, i.e., at a greater distance, multi-point surface positioning can be formed, thereby improving positioning accuracy. This ensures precise operation and reduces errors in processes such as surface mounting, soldering, reflow soldering, and solder paste application during the production process. The greater distance of the positioning holes 1 also helps to reduce signal interference between different circuit parts. In high-frequency and high-speed circuit design, maintaining sufficient distance can reduce cross-interference between signals and improve signal quality.

[0130] Example 3

[0131] After fabricating the PCB based on Embodiment 1 above, performance testing of the PCB is still required. Preparation before testing includes: ensuring the testing environment meets the requirements, such as temperature, humidity, and electrostatic discharge protection. Simultaneously, prepare the necessary equipment and tools, such as oscilloscopes, signal generators, and multifunction testers, and calibrate them to ensure testing accuracy.

[0132] Understanding Product Requirements and Specifications: Carefully study the PCB design documents and specifications to understand the specific requirements and specifications of the product, including electrical performance, dimensions, shape, materials, etc. This will help determine the focus and methods of testing, as well as set appropriate test parameters.

[0133] Visual inspection: Carefully inspect the PCB for any obvious damage, stains, or defects. This includes checking the solder mask for integrity, absence of bubbles or cracks, and the gold plating for uniformity and no peeling.

[0134] The performance testing course includes:

[0135] Electrical performance testing: The electrical performance of the PCB is tested using equipment such as multi-function testers and oscilloscopes. The test content may include parameters such as conductivity, insulation, resistance, capacitance, and inductance to ensure that the electrical performance of the circuit board meets the design requirements. The specific values ​​of the parameters depend on the PCB material and design requirements.

[0136] Functional testing: Based on the specific functions and requirements of the product, design corresponding test plans to verify the functionality of the PCB. This can be achieved by simulating actual working conditions, applying signals or voltages to the circuit board, and observing its output or response.

[0137] Reliability Testing: Reliability testing is performed on the PCB to evaluate its stability and durability under various harsh environments. Tests may include temperature cycling, humidity testing, and vibration testing to simulate various situations the product might encounter in real-world use. Specific test parameter values ​​depend on the PCB material and design requirements. After testing, the PCB product of the required dimensions is machined according to customer specifications.

[0138] Example 4

[0139] The PCB size obtained by this application is between 760mm and 1245mm, mostly 1000mm. The PCB size obtained by this method is the optimal result of this method, but it is not the only result. PCBs of different sizes obtained by this method can be used as alternatives to this solution. However, it is worth noting that although large-size PCBs allow designers to separate circuit components and wiring space further apart, which helps to reduce signal interference and noise, in some cases, if the line is too long, the impedance will also increase accordingly, thereby weakening the noise immunity.

[0140] Larger PCBs may have lower total costs due to the reduced area required, but unit costs may be higher, and longer circuits may lead to increased material costs.

[0141] When the PCB size is too small, the components are arranged too closely due to space constraints, which may lead to increased signal interference and noise, affecting signal quality.

[0142] An excessively small PCB size may make the assembly process difficult, and may also make fault identification and location more complicated, increasing maintenance costs and downtime. Due to the small PCB size and short distance between components, poor heat dissipation may occur, which in turn affects equipment performance.

[0143] Example 5

[0144] In summary, the design principle of this scheme can be derived as follows:

[0145] Material cutting: Cutting large-size substrates into smaller core boards that conform to the PNL dimensions of the PCB board;

[0146] Drill positioning hole 1: Use pre-expansion and contraction to drill positioning hole 1 with the first expansion and contraction amount on the edge of the core board (the expansion and contraction amount is given by the lamination engineer according to the material, board thickness and copper thickness). Determine the position range of the circuit pattern of positioning hole 1 according to the positioning hole 1.

[0147] Drilling rivet holes 2: Determine the position range of the rivet hole 2 line pattern that coincides with the position range of the positioning hole 1 line pattern according to the position range of the positioning hole 1 line pattern. According to the position range of the rivet hole 2 line pattern, drill a number of rivet holes 2 containing the second pre-expansion and contraction amount in the core board.

[0148] Lamination: The boards are stacked according to the layer order, and a prepreg (PP) sheet is added between each core board according to the customer's thickness requirements. The prepreg is completely cured by high temperature and high pressure of the press, so that all the core boards are pressed into a PCB semi-finished product with an ordered structure.

[0149] Drilling: Drilling holes on the PCB board that need to conduct inner layer circuits, and removing burrs and rough edges from the hole openings;

[0150] Plating copper: Copper is deposited on the surface and inside the holes of a PCB using chemical methods to create conductivity.

[0151] Electroplating: On the basis of immersion copper, the copper in the holes and the copper on the surface are thickened by electroplating to make the copper on the surface and the copper in the holes meet the customer's requirements.

[0152] Solder mask: A layer of ink printed on the PCB surface to provide protection;

[0153] Text: Print the text and logos required by the customer on the outer layer of the PCB;

[0154] Immersion gold plating: A thin layer of gold is plated onto the circuit pattern to protect the circuit.

[0155] Testing: Perform performance testing and visual inspection on the PCB to ensure product quality;

[0156] Molding: Prototype the finished PCB graphic of the required size from the customer.

[0157] In summary, this solution takes into account expansion and contraction factors. For cases with inconsistent core board thickness, it incorporates rivet holes 2 with a second pre-expansion / contraction amount. This second pre-expansion / contraction amount offsets the actual expansion and contraction changes of the rivet holes 2 after core board etching, preventing misalignment. Similarly, it uses positioning holes 1 with a first pre-expansion / contraction amount to offset the actual expansion and contraction of the core board pattern after lamination, preventing lamination layer misalignment. By incorporating positioning holes 1 with the first pre-expansion / contraction amount and rivet holes 2 with the second pre-expansion / contraction amount, this solution addresses the problem of inconsistent expansion and contraction coefficients in core boards of different thicknesses or copper thicknesses during the lamination and riveting process when drilling rivet holes 2 with a drilling machine in the fabrication of large-size boards. This inconsistency in the expansion and contraction coefficients leads to rivet misalignment or failure to fit during lamination and riveting.

[0158] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for manufacturing a large-size PCB board, characterized in that, The large-size PCB board has a size greater than 760mm, and the manufacturing method includes: Several positioning holes containing the first pre-expansion and contraction amount are drilled in the core board, and the circuit pattern range is determined according to the positioning holes; The rivet hole circuit pattern range that overlaps with the circuit pattern range of the positioning hole is determined according to the circuit pattern range of the positioning hole. Several rivet holes containing the second pre-expansion and contraction amount are drilled within the circuit pattern range of the rivet hole. The first pre-expansion / contraction amount is the sum of the etching expansion / contraction amount and the pressing expansion / contraction amount during the process from blanking to pressing of the core board; the second pre-expansion / contraction amount is the etching expansion / contraction amount during the process from blanking to etching of the core board. The rivet hole, after being pressed and fixed, only exhibits etching expansion and contraction, but not compression expansion and contraction.

2. The method for manufacturing a large-size PCB board according to claim 1, characterized in that, The expression for the etching expansion / contraction is: SK = (LS) / L; Where SK is the etching expansion / contraction amount, L is the theoretical distance between the two selected positioning holes, and S is the actual distance between the two selected positioning holes after etching. The expression for the compression expansion / contraction is: YH = (SD) / L; Where YH is the compression expansion and contraction amount, and D is the actual distance between the two positioning holes selected after compression.

3. The method for manufacturing a large-size PCB board according to claim 1, characterized in that, After drilling a plurality of rivet holes containing a second pre-expansion amount within the rivet hole line pattern area, the process includes: Obtain the core board with completed drilling, arrange the core boards in the order of layers, add a prepreg between two adjacent core boards, and press the core boards and the prepreg into a core board with a sequential structure using a press.

4. The method for manufacturing a large-size PCB board according to claim 3, characterized in that, After pressing the core board and PP into a core board with a sequential structure using a press, the process includes: Drill through holes in the core board and clean the burrs from the openings of the positioning holes, rivet holes, and through holes; After removing the burrs, the via is copper plated.

5. The method for manufacturing a large-size PCB board according to claim 4, characterized in that, After removing the burrs, the positioning holes and rivet holes are copper-plated, including: The surface of the core board is coated with copper to obtain a core board covered with a copper layer; The surface of the copper layer is used to create a circuit pattern, and the copper layer is etched to remove unwanted copper foil.

6. The method for manufacturing a large-size PCB board according to claim 5, characterized in that, The process of fabricating a circuit pattern on the surface of the copper layer, and then etching the copper layer to remove unwanted copper foil, includes: The core board is subjected to solder resist treatment, and the surface of the circuit pattern is gold plated. The core board after gold plating is subjected to performance testing and visual inspection.

7. The method for manufacturing a large-size PCB board according to claim 6, characterized in that, The performance tests include insulation resistance testing, welding testing, and signal testing.

8. The method for manufacturing a large-size PCB board according to claim 1, characterized in that, The diameter of the positioning hole and the rivet hole is 2mm.

9. The method for manufacturing a large-size PCB board according to claim 1, characterized in that, Before drilling a plurality of positioning holes containing a first pre-expansion amount in the core board, the method further includes: The large substrate is cut into several core boards of the same size.

10. The method for manufacturing a large-size PCB board according to claim 9, characterized in that, The length of the core board is between 760mm and 1245mm.

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