Circuit board manufacturing method and circuit board

Abstract

The application relates to the technical field of circuit board manufacturing, and provides a circuit board manufacturing method and a circuit board. The circuit board manufacturing method comprises the following steps: preparing a circuit board blank, forming a gold immersion metal layer on the surface of the circuit board blank, and dividing the gold immersion metal layer into an external conductive part and a pad part for welding electronic components; immersing the circuit board blank in a sealing agent to fill and seal the micropores on the surface of the gold immersion metal layer; covering the surface of the external conductive part with a volatile-proof film to shield and protect the surface; welding the electronic components to the pad part of the circuit board blank; and tearing off the volatile-proof film after the welding is completed. The external conductive part which does not need to be welded is covered with a volatile-proof film before welding to shield and protect the external conductive part, so that the sealing structure of the external conductive part is prevented from volatilizing, being damaged or failing in the subsequent high-temperature welding process, the sealing structure of the external conductive part is reserved, the finished product after the welding has excellent and stable corrosion resistance, and the corrosion resistance of the circuit board is improved.

Description

Technical Field

[0001] This application relates to the field of circuit board manufacturing technology, and more particularly to a method for manufacturing a circuit board and a circuit board. Background Technology

[0002] Salt spray testing is an artificially accelerated environmental simulation test method. It involves atomizing a salt solution of a certain concentration and spraying it onto the surface of a sample in a sealed, temperature-controlled chamber to simulate a marine or saline atmospheric environment, thereby assessing the corrosion resistance of products or metallic materials. During salt spray testing, the electrolyte solution easily penetrates through micropores into the nickel and copper layers, forming tiny batteries that lead to electrochemical corrosion, resulting in coating damage and salt spray failure.

[0003] In related technologies, after the high-temperature process of the bare circuit board in the circuit board manufacturing method, the vias are sealed, forming a protective film on the gold surface to prevent electrolyte solution from seeping into the micropores. However, this solution is only suitable for circuit board products without components. Because the components cannot be immersed in the sealing solution and the protective film cannot withstand the high temperature of reflow soldering, it will evaporate and deteriorate. Therefore, products after surface mount reflow soldering still generally have failure problems in salt spray tests, meaning that the corrosion resistance of products after surface mount reflow soldering is poor. Summary of the Invention

[0004] The purpose of this application is to provide a circuit board manufacturing method and a circuit board, which aims to solve the technical problem of poor corrosion resistance of products after surface mount reflow soldering.

[0005] To achieve the above objectives, the technical solution adopted in the first aspect of this application is: a circuit board manufacturing method, comprising: A blank circuit board is prepared, and an immersion gold metal layer is formed on the surface of the blank circuit board. The surface of the immersion gold metal layer has micropores, and the immersion gold metal layer is divided into an external conductive part and a pad part for soldering electronic components. The blank circuit board is soaked in a sealing agent to fill and seal the micropores on the surface of the immersion gold metal layer. The surface of the external conductive part is covered with an anti-volatile film for shielding and protection. Solder electronic components to the pad portion of the blank circuit board; After welding is completed, remove the anti-volatile film.

[0006] The beneficial effects of the circuit board manufacturing method provided in the first aspect of this application are as follows: First, the entire immersion gold metal layer is uniformly sealed to block the micropores on the surface of the immersion gold metal layer, effectively avoiding electrochemical corrosion caused by electrolyte penetration into the micropores under salt spray environment. At the same time, before soldering, the external conductive parts that do not need to be soldered are pre-covered with an anti-volatile film for shielding and protection, preventing the sealing structure of the external conductive parts from volatilizing, breaking or failing during the subsequent high-temperature soldering process. The sealing and protection structure of the external conductive parts is retained, so that the finished product after soldering still has excellent and stable salt spray corrosion resistance, improving the overall corrosion resistance and product life of the circuit board after surface mounting.

[0007] In some embodiments, when the surface of the external conductive portion is covered with an anti-volatile film, the anti-volatile film is pressed together using a vacuum pressurization method.

[0008] In some embodiments, the anti-volatile film lamination process parameters are set as follows: temperature 60°C to 80°C, pre-pressing time 3 to 10 seconds, molding time 3 to 10 seconds, and molding pressure 15 kg / cm². 2 Up to 25kg / cm 2 .

[0009] In some embodiments, the anti-volatile film is made of a high-temperature resistant material.

[0010] In some embodiments, soldering electronic components to the pad portion of the blank circuit board includes: The electronic components are mounted on the pad portion; A heat insulation cover plate is laid on the surface of the anti-volatile film to block high temperature, and the area where the heat insulation cover plate is laid avoids the electronic components. The electronic components are connected to the pads by a welding process.

[0011] In some embodiments, the provision of a heat-insulating cover plate on the surface of the anti-volatile film includes: The blank circuit board with the electronic components mounted is positioned and placed on the mounting fixture; The heat insulation cover is aligned and fixed to the patch fixture and covers the anti-volatile film area accordingly, so that the heat insulation cover shields the anti-volatile film and avoids the electronic component area.

[0012] In some embodiments, the heat insulation cover is made of a high-temperature resistant heat insulation material, and the heat insulation cover is used to block the conduction of welding heat to the anti-volatile membrane.

[0013] In some embodiments, the circuit board manufacturing method further includes: After removing the anti-volatile film, the surface of the external conductive part is inspected.

[0014] In some embodiments, after the anti-volatile film is applied to the surface of the external conductive portion and before the electronic components are mounted, the bare circuit board is inspected to check the adhesion status of the anti-volatile film.

[0015] To achieve the above objectives, the technical solution adopted in the second aspect of this application is: a circuit board manufactured by the circuit board manufacturing method of the first aspect of the embodiment.

[0016] The beneficial effects of the circuit board provided in the second aspect embodiment of this application are: the sealing and protection structure of the external conductive part is relatively complete, it has excellent and stable resistance to salt spray corrosion, strong corrosion resistance and long product service life. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a portion of the circuit board manufacturing method in one embodiment of this application; Figure 2 This is a flowchart of a circuit board manufacturing method in one embodiment of this application; Figure 3 yes Figure 2 A flowchart of step S400 in the circuit board manufacturing method shown; Figure 4 yes Figure 3 The flowchart for step S420.

[0019] Figure label: 1. Blank circuit board; 11. Circuit board substrate; 12. External conductive part; 13. Solder pad part; 14. Circuit pattern; 15. Copper solder pad area; 16. External conductive area; 17. Anti-volatile film; 18. Heat insulation cover plate; 19. SMT fixture; 110. Covering film. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0021] In the description of this application, it should be understood that the terms "length", "width", "thickness", "top", "bottom", "inner", "outer", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] To facilitate a clear description of the technical solutions of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0023] In this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In this application, "and / or" is merely a way of describing the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0025] It should be noted that, in this application, the terms "in one embodiment," "in one implementation," "exemplarily," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "in one embodiment," "in one implementation," "exemplarily," or "for example" should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "in one embodiment," "exemplarily," and "for example" is intended to present the relevant concepts in a specific manner.

[0026] Salt spray testing is an artificially accelerated environmental simulation test method. It involves atomizing a salt solution of a certain concentration and spraying it onto the surface of a sample in a sealed, temperature-controlled chamber to simulate a marine or saline atmospheric environment, thereby assessing the corrosion resistance of products or metallic materials. During salt spray testing, the electrolyte solution easily penetrates through micropores into the nickel and copper layers, forming tiny batteries that lead to electrochemical corrosion, resulting in coating damage and salt spray failure.

[0027] In related technologies, after the high-temperature process of the bare circuit board in the circuit board manufacturing method, the vias are sealed, forming a protective film on the gold surface to prevent electrolyte solution from seeping into the micropores. However, this solution is only suitable for circuit board products without components. Because the components cannot be immersed in the sealing solution and the protective film cannot withstand the high temperature of reflow soldering, it will evaporate and deteriorate. Therefore, products after surface mount reflow soldering still generally have failure problems in salt spray tests, meaning that the corrosion resistance of products after surface mount reflow soldering is poor.

[0028] In view of the above-mentioned technical problems, this application provides a circuit board manufacturing method and a circuit board, aiming to solve the technical problem of poor corrosion resistance of products after surface mount reflow soldering.

[0029] To illustrate the technical solution of this application, the following description is provided in conjunction with specific accompanying drawings and embodiments.

[0030] Please refer to Figure 1 and Figure 2 This application provides a method for manufacturing a circuit board, including: S100: Prepare a blank circuit board 1. An immersion gold metal layer is formed on the surface of the blank circuit board 1. The surface of the immersion gold metal layer has micropores. The immersion gold metal layer is divided into an external conductive portion 12 and a pad portion 13 for soldering electronic components.

[0031] It should be noted that, according to the "Atmospheric Corrosion Behavior and Mechanism of Electronic Materials," micropores exist on the surface of the immersion gold layer on circuit boards, between the crystal lattice of the immersion gold layer, and between the particles of the immersion gold layer. These micropores can only be completely eliminated when the thickness of the immersion gold layer reaches 5 μm. In actual production, due to cost and process limitations, the thickness of the immersion gold layer is generally controlled between 0.05 μm and 0.10 μm, and it is impossible to reach 5 μm. Therefore, micropores inevitably exist on the surface of the immersion gold layer.

[0032] Step S100 is the pre-forming process of the circuit board, which involves at least the following steps in sequence: blanking, drilling, electroplating, pattern making, AOI (Automatic Optical Inspection), lamination, immersion gold surface treatment, character printing, and semi-finished product assembly (for flexible circuit boards) to complete the preparation of the blank board. The specific process operations of each step in step S100 are as follows: Blanking process: Select a circuit board substrate 11 that meets the specifications, cut and trim it according to the product design dimensions, remove excess waste and burrs from the edges of the circuit board substrate 11, and obtain a cut substrate with regular dimensions and a flat surface, providing standard blanks for subsequent precision processing. Alternatively, the entire roll of circuit board substrate 11 can be sent to the drilling process. Drilling process: According to the circuit board circuit design drawings, use mechanical drilling or laser drilling to accurately drill holes in the cut substrate, processing positioning holes, through holes, and functional holes to meet the structural requirements of subsequent interlayer conduction and alignment assembly, ensuring that the hole position accuracy meets the process standards. Electroplating Process: Electroplating is performed on the substrate surface and hole walls after drilling. Copper layers are deposited on the hole walls and conductive areas of the substrate surface through electrochemical deposition, achieving hole wall metallization, opening up conductive paths between circuit layers, and ensuring the conductivity of subsequent circuits. Pattern Making Process: Through a complete set of processes including lamination, exposure, development, and etching, the preset circuit pattern is transferred to the surface of the circuit board substrate 11. Excess copper foil is removed, and the required circuit pattern 14, copper pad area 15, and external conductive area 16 are precisely formed, completing the circuit board circuit shaping. AOI Process: Automated optical inspection equipment is used to perform full-area scanning inspection of the patterned circuit board, automatically identifying appearance and circuit defects such as open circuits, short circuits, line misalignment, residual copper, and gaps. Qualified circuit board substrates are selected, and defective products are rejected to prevent defective boards from entering subsequent processes. Lamination Process: According to the structural requirements of the circuit board product, the reinforcing material is precisely aligned with the substrate, and constant temperature and pressure lamination is performed using lamination equipment to ensure tight bonding and curing of each layer, improving the overall structural strength and flatness of the circuit board, and ensuring product structural stability. Immersion gold surface treatment process: The qualified circuit board after lamination undergoes immersion gold treatment. Through a chemical displacement reaction, a uniform and dense immersion gold metal layer is deposited on the surface of the exposed copper pad area 15 and the external conductive area 16, isolating the copper layer from external air and moisture, while ensuring conductivity and solderability. The formed immersion gold metal layer is precisely divided into two functional areas according to its functional attributes: the external conductive part 12 for subsequent bonding and connection to achieve circuit conduction, and the pad part 13 for mounting and soldering electronic components. Before the immersion gold process, a cover film 110 is laid on the circuit pattern 14, while the copper pad area 15 and the external conductive area 16 are exposed.Character printing process: Using screen printing or laser marking, component identification, model, batch, and alignment reference information are printed on the circuit board surface. This facilitates subsequent surface mount technology (SMT), assembly, testing, and product traceability, meeting the requirements of standardized mass production operations. Semi-finished product assembly process: Considering the characteristics of flexible circuit boards, PI (Polyimide) reinforcing sheets, FR4 (Flame Retardant Type 4) reinforcing boards, steel sheets, or aluminum sheets are assembled in designated areas on the board surface. This compensates for the softness and insufficient support of flexible boards, increases the local thickness and structural support of the circuit board, and improves the structural stability during subsequent soldering and use. Through the above complete process, a complete circuit board (1) with well-formed circuitry, excellent support performance, and a zoned immersion gold metal layer on the surface is finally obtained, laying a reliable structural foundation for subsequent zoned differentiated protection and component soldering operations.

[0033] S200: Use a sealing agent to soak the empty circuit board 1 to fill and seal the micropores on the surface of the immersion gold metal layer.

[0034] In step S200, a sealing agent (water-soluble organic gold-plating sealant, nickel-gold composite inorganic sealant, or ultra-thin polymer film-forming sealant) is used to soak the bare circuit board 1, performing a full-area immersion sealing treatment on the formed immersion gold metal layer. In step S200, the immersion method allows the sealing agent to fully penetrate and fill the micropores on the surface of the immersion gold metal layer, sealing plating defects. After the sealing agent cures, a sealing structure is formed to block the pores. The output of step S200 is a bare circuit board 1 with surface micropores sealed, forming a dense and stable sealing protective layer. This effectively blocks the channels for electrolytes to penetrate into the micropores under salt spray conditions, avoiding the risk of electrochemical corrosion of the nickel and copper layers from the source.

[0035] S300: The surface of the external conductive part 12 is covered with an anti-volatile film 17 for shielding and protection.

[0036] In step S300, the film is precisely aligned and applied, covering only the external conductive portion 12, leaving the solder pad portion 13 exposed. This does not affect subsequent soldering operations, achieving targeted protection for non-soldering functional areas. The output of step S300 is a circuit board to be mounted with partitioned protection molding. It is understood that the anti-volatile film 17 is a dense film layer. Under the high temperature of subsequent soldering, if the sealing agent at the external conductive portion 12 vaporizes due to heat, the anti-volatile film 17 can constrain the vaporized components, inhibiting the outward escape of the sealing material, thereby achieving an anti-volatile effect. After the bare circuit board 1 cools down, the constrained sealing components re-condense and solidify, thus maintaining the integrity of the sealing structure of the external conductive portion 12. The anti-volatile film 17 is then removed. Optionally, the anti-volatile film 17 can be made of a film material with heat insulation capabilities to further block the conduction of soldering heat to the sealing agent, reducing the degree of heat volatilization of the sealing agent and continuously ensuring the integrity of the sealing structure.

[0037] S400: Solder electronic components to the pad portion 13 of the blank board 1 of the circuit board.

[0038] In step S400, relying on the good solderability of the exposed pad portion 13, the electronic components are mounted and fixed, and the circuit is made conductive, through a general soldering process (reflow soldering, wave soldering, or laser soldering). The output of step S400 is a semi-finished circuit board with a protective film and assembled electronic components, ensuring the reliability of soldering and the stability of circuit conductivity throughout the process.

[0039] S500: Remove the anti-volatile film 17.

[0040] After all welding processes are completed and the board surface has cooled sufficiently, the anti-volatile film 17 on the surface of the external conductive part 12 is peeled off. The resulting product is a semi-finished circuit board with a complete sealing structure for the external conductive part 12 and firmly welded electronic components. This ultimately achieves long-term corrosion-resistant protection for the immersion gold layer of the circuit board with electronic components, solving the core problem of sealing failure after welding in traditional processes. Specifically, when peeling off the anti-volatile film 17, it is peeled off at a uniform speed along an inclined direction to avoid damaging the sealing structure of the immersion gold metal layer surface during the peeling process.

[0041] In the circuit board manufacturing method provided in the first aspect of this application, the entire immersion gold metal layer is first uniformly sealed to block the micropores on the surface of the immersion gold metal layer, effectively avoiding electrochemical corrosion caused by electrolyte penetration into the micropores under salt spray environment. At the same time, before soldering, the external conductive parts 12 that do not need to be soldered are pre-covered with an anti-volatile film 17 for shielding and protection, to prevent the sealing structure of the external conductive parts 12 from volatilizing, breaking or failing during the subsequent high-temperature soldering process, thus retaining the sealing and protection structure of the external conductive parts 12, so that the finished product after soldering still has excellent and stable salt spray corrosion resistance, improving the overall corrosion resistance and product life of the circuit board after surface mounting.

[0042] Please refer to Figure 1 In some embodiments, the anti-volatile film 17 is also disposed on the circuit pattern 14.

[0043] Understandably, conventional processes that only coat the external conductive area 16 with film have extremely high requirements for film alignment accuracy and film cutting size accuracy due to the small area and fine boundaries of the protected area. This can easily lead to problems such as alignment misalignment, undercutting, and incomplete coating. In the above embodiment, the anti-volatile film 17 not only covers the external conductive part 12, but also simultaneously covers the circuit pattern 14 area, extending the coating area to the circuit pattern 14 area. This increases the overall effective coating area and improves the tolerance space, effectively reducing the adverse risks caused by equipment alignment deviation, manual bonding error, and cutting size deviation. It also significantly relaxes the process accuracy control requirements and reduces the difficulty of production and processing. Meanwhile, the large-area integrated coating method can ensure that the film is flat and has good boundary continuity, without defects such as local suspension, poor adhesion, and broken points. While accurately avoiding the soldering area of ​​the pads and ensuring that the soldering performance is not affected, it can achieve high-temperature protection for the 12-hole sealing structure of the external conductive part, and simultaneously form high-temperature isolation protection for the 14 areas of the precision circuit pattern. While simplifying the process and improving the mass production processability and batch consistency, it can comprehensively improve the overall high-temperature resistance and anti-aging performance of the circuit board.

[0044] In some embodiments, the original cover film 110 on the circuit pattern 14 is retained before the blank board 1 is soaked in a sealing agent.

[0045] In the above embodiment, the area of ​​circuit pattern 14 relies on the original cover film 110 to form a front protective barrier throughout, so that the sealing agent immersion process only fills and seals the micropores in the immersion gold metal layer area, and the solution does not directly contact the exposed circuit substrate. This effectively avoids the sealing solution from wetting, corroding, and oxidizing the precision copper circuit and the circuit substrate, and eliminates problems such as micro-corrosion of the circuit, decreased insulation performance, and whitening and discoloration of the board surface caused by solution residue, thus accurately ensuring the electrical performance and structural integrity of circuit pattern 14.

[0046] Please refer to Figure 1 In some embodiments, the covering film 110 on the circuit pattern 14 is not removed before the anti-volatile film 17 is applied to the external conductive portion 12 and the circuit pattern 14 for shielding and protection.

[0047] In the above embodiment, before covering the circuit pattern 14 with the anti-volatile film 17 for shielding protection, the original covering film 110 on the circuit pattern 14 is retained and not removed. This creates a double-layered protective structure of "original covering film 110 + anti-volatile film 17" in the circuit area. Under high-temperature soldering conditions, the double-layer film can block heat radiation and heat conduction layer by layer, avoiding the defects of local heat penetration and aging damage that exist in single-film protection. This effectively protects the stability of the precision circuit structure and prevents problems such as high-temperature oxidation, blackening, and aging failure. While ensuring the conductivity and appearance quality of the circuit board, it further improves the overall reliability and salt spray corrosion resistance of the finished product. Furthermore, the original covering film 110 in the circuit pattern 14 area can provide basic protection for the circuit substrate and copper foil circuit, preventing scratches, contamination, and corrosion damage to the precision circuit during the vacuum lamination process, and ensuring the integrity and conductivity stability of the circuit pattern 14.

[0048] Optionally, in the above embodiment, the cover film 110 is removed at the same time as the anti-volatile film 17. This eliminates the redundant steps of removing, cleaning, and re-laminating the circuit cover film 110, simplifying the overall process and improving production efficiency.

[0049] In some embodiments, when the anti-volatile film 17 is covered on the surface of the external conductive part 12, the anti-volatile film 17 is pressed together by vacuum pressure.

[0050] In the above embodiment, a vacuum pressurization process is used to bond the anti-volatile film 17. The feed consists of a sealed blank circuit board 1 and the anti-volatile film 17. The air between the film and the board surface is eliminated through a vacuum environment, and the pressurization process ensures that the film is bonded without bubbles, wrinkles, or misalignment. The output is a protective circuit board with a smooth coating, tight bonding, and excellent sealing performance. The purpose of this process is to ensure that the anti-volatile film 17 is completely bonded to the external conductive parts 12, eliminating heat and liquid leakage problems and improving the protective stability during subsequent high-temperature welding processes.

[0051] In some embodiments, the lamination process parameters for the anti-volatile film 17 are set as follows: temperature 60°C to 80°C, pre-pressing time 3 to 10 seconds, molding time 3 to 10 seconds, and molding pressure 15 kg / cm². 2 Up to 25kg / cm 2 .

[0052] In the above embodiments, the vacuum pressing process parameters are refined, specifying a pressing temperature of 60°C to 80°C, a pre-pressing time of 3 to 10 seconds, a molding time of 3 to 10 seconds, and a molding pressure of 15 kg / cm². 2 Up to 25kg / cm 2Precise process parameters. The optimal process range for the immersion gold sealing structure and the high-temperature resistant anti-volatile film 17 is adapted to this solution. The low-temperature, short-time pressurization mode ensures a firm bond to the anti-volatile film 17, preventing lifting and detachment, while avoiding damage to the newly formed microporous filling structure of the immersion gold sealing structure by high temperature and prolonged pressure. This precisely balances the film bonding accuracy and the integrity of the sealing structure, ensuring no loss of pre-protection effect. Optional pressing temperatures are 65℃, 70℃, or 75℃. Optional molding times are 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, or 9 seconds. Optional molding pressure is 16 kg / cm². 2 18kg / cm 2 20kg / cm 2 22kg / cm 2 Or 24kg / cm 2 .

[0053] In some embodiments, the anti-volatile membrane 17 is made of a high-temperature resistant material. This allows the anti-volatile membrane 17 to block high temperatures during the welding process, and the anti-volatile membrane 17 can be removed without any residue after welding.

[0054] In the above embodiments, the material properties and functional characteristics of the anti-volatile membrane 17 are defined, and a high-temperature resistant material is selected to prepare the anti-volatile membrane 17. This material characteristic enables the anti-volatile membrane 17 to withstand the instantaneous high-temperature impact of the welding process, without melting, decomposing, or failing during the welding process. It can not only stably block the conduction of the high temperature of welding to the lower sealing structure, but also prevent the vaporized sealing components from escaping outward, thereby preventing the evaporation of the sealing agent in the sealing structure. At the same time, the anti-volatile membrane 17 has low adhesion characteristics, and can be completely and easily peeled off after welding, without any residue remaining on the surface of the immersion gold layer, avoiding secondary contamination of the sealing structure, and balancing high-temperature protection performance and cleanliness after peeling.

[0055] Optionally, the high-temperature resistant material used to make the anti-volatile film 17 is: polyimide film, fluorine-based high-temperature resistant film, liquid crystal polymer film, etc.

[0056] Please refer to Figure 3 In some embodiments, S400: soldering electronic components to the pad portion 13 of the blank circuit board 1 includes: S410: Mount electronic components on pad portion 13.

[0057] S420: A heat insulation cover plate 18 is laid on the surface of the anti-volatile membrane 17 to block high temperature. The area where the heat insulation cover plate 18 is laid avoids electronic components.

[0058] S430: A welding process is used to weld electronic components to the pad portion 13.

[0059] In the above embodiment, electronic components are first precisely mounted on the circuit board pads 13, and the component positioning pretreatment is completed after mounting. Then, a heat insulation cover plate 18 is laid on the surface of the anti-volatile film 17, strictly avoiding the area where the electronic components are placed. The heat insulation cover plate 18 fully covers the area of ​​the anti-volatile film 17, forming a double-layer high-temperature protection structure. Finally, the components are welded using a general welding process, and the output is a double-layer protected, welded circuit board semi-finished product.

[0060] In the above embodiment, an insulation cover plate 18 is added to further reduce welding heat radiation and heat conduction on the basis of the anti-volatile film 17 blocking high temperature, providing double protection for the sealing structure of the external conductive part 12 and eliminating the problem of evaporation and damage of the sealing layer caused by high temperature.

[0061] Understandably, the heat insulation cover 18 is made of high-temperature resistant heat insulation material and is used to block the conduction of welding heat to the anti-volatile membrane 17. Optionally, the heat insulation cover 18 can be made of high-temperature resistant silicone, polyimide, metal, composite heat insulation material (glass fiber and silicone rubber composite), etc.

[0062] Please refer to Figure 1 and Figure 4 In some embodiments, step S420: Applying a heat-insulating cover plate 18 to the surface of the anti-volatile film 17 includes: Step S421: Position the blank circuit board 1 with electronic components mounted on the mounting fixture 19.

[0063] Step S422: Align and fix the heat insulation cover plate 18 to the patch fixture 19 and cover the anti-volatile film 17 area accordingly, so that the heat insulation cover plate 18 shields the anti-volatile film 17 and avoids the electronic component area.

[0064] In the above embodiment, the specific process of soldering electronic components to the pad portion 13 of the blank circuit board 1 is as follows: The blank circuit board 1 with the electronic components mounted is positioned on a special mounting fixture 19 to achieve overall board surface fixation and precise position calibration, effectively avoiding problems such as board surface offset, component misalignment, and alignment deviation during subsequent soldering; then, the heat insulation cover 18 is precisely aligned and fixed to the corresponding position on the mounting fixture 19, so that the heat insulation cover 18 covers the entire area of ​​the anti-volatile film 17, while precisely avoiding the area where electronic components are placed, eliminating blind spots and shielding deviations. After the heat insulation cover 18 is positioned, a general soldering process adapted to the circuit board manufacturing process is used to complete the fusion bonding and circuit connection between the electronic components and the pad portion 13.

[0065] In the above embodiments, the use of fixture-assisted positioning and layout can significantly improve the layout accuracy and bonding stability of the heat insulation cover plate 18, ensuring full coverage of the high-temperature protection area and no obstruction of the non-protection area. Under the premise of ensuring welding reliability, it can achieve all-round high-temperature protection of the external conductive part 12 anti-volatile film 17 and the lower sealing structure, and is suitable for standardized, high-precision and high-consistency mass production operations.

[0066] In the above embodiment, the heat insulation cover plate 18 is aligned and fixed to the mounting fixture 19, which can press the blank circuit board 1 onto the mounting fixture 19, flatten the blank circuit board 1, ensure the board surface is flat, and facilitate good soldering of electronic components and pad portion 13.

[0067] Please refer to Figure 2 In some embodiments, the circuit board manufacturing method further includes: S600: After removing the anti-volatile film 17, inspect the surface of the external conductive part 12.

[0068] In the above embodiment, after removing the anti-volatile film 17, a special inspection is carried out on the surface of the external conductive part 12 of the circuit board. The focus is on checking whether there is residual adhesive from the removal of the anti-volatile film 17 on the board surface and whether the sealing structure is complete and intact. After inspection, finished products that are qualified and without defects are selected, while defective products with residual adhesive pollution and broken sealing are removed, so as to achieve finished product quality control and ensure the consistency of corrosion resistance of batch products.

[0069] In some embodiments, after the anti-volatile film 17 is covered on the surface of the external conductive part 12 and before the electronic components are mounted, the blank board 1 of the circuit board is inspected to check the adhesion status of the anti-volatile film 17.

[0070] In the above implementation, after the anti-volatile film 17 is laminated but before electronic components are mounted, the bare circuit board 1 is fully inspected to check the flatness, sealing, and alignment accuracy of the anti-volatile film 17. By conducting pre-inspection, defects such as bubbles, misalignment, missing parts, and lifting of the film are detected in advance and corrected in time. This prevents defective boards from entering the chip mounting and soldering processes, and prevents high-temperature protection failure and salt spray test failure caused by poor film lamination from the source, thus achieving full-process quality control.

[0071] Optionally, the specific inspection method includes a combination of visual inspection and auxiliary fixture inspection: First, a full-area visual inspection of the coated area is carried out using high-definition magnifying visual equipment or a microscope, focusing on whether there are defects such as missing application, misalignment, edge lifting, wrinkles, or damage to the anti-volatile film 17. Second, regarding the internal bonding status of the film, the presence of air bubbles, incomplete bonding, or localized gaps between the film and the gold surface is checked through light transmission inspection or flatness fixture verification. At the same time, the coverage boundary of the anti-volatile film 17 is verified to ensure that the film completely covers the external conductive part 12 and does not obstruct the pad area. During the inspection process, blank circuit boards 1 with bonding defects are pre-screened for rework and re-vacuum pressure bonding. Only those that pass the rework can proceed to the next placement process.

[0072] Understandably, the circuit board manufacturing method also includes the following steps: After completing the soldering operation and removing the anti-volatile film 17, the blank circuit board 1 with soldered electronic components is smoothly removed from the mounting fixture 19. After detaching from the fixture positioning structure, it enters the standardized post-processing flow, such as dispensing, molding, FQC (Final Quality Control), and finished product packaging, thus completing the final mass production process of the circuit board. Among them, the dispensing process is used to reinforce and seal the solder joints of electronic components and the gaps between the board edges, improving the circuit board's shock resistance, moisture resistance, and structural stability. The molding process involves punching, shaping, and trimming according to the product's shape and specifications, removing process waste, and correcting the board's shape to ensure that the product's dimensional accuracy meets the shipping standards. The FQC finished product full inspection process involves sampling and full-item verification of the circuit board's appearance, soldering quality, sealing integrity, conductivity, and corrosion resistance, screening qualified finished products and rejecting defective products. Finally, the finished product packaging process completes the dustproof, moisture-proof, and anti-static sealing, realizing standardized warehousing and shipment of finished products. The entire set of downstream processes are smoothly connected and standardized, which can reliably guarantee the quality and reliability of batch finished products.

[0073] Please refer to Figure 1 Both the top and bottom surfaces of the blank circuit board 1 are coated with an immersion gold metal layer, and electronic components can be soldered onto both surfaces. The soldering operation employs a double-sided, step-by-step soldering process; after soldering components on one side, the soldering operation on the other side is performed. Optionally, the anti-volatile film 17 on both surfaces is removed after double-sided soldering. This ensures continuous high-temperature barrier protection during both high-temperature soldering processes, guaranteeing that the double-sided immersion gold sealing structure maintains a complete and dense protective state. This results in excellent and balanced salt spray and corrosion resistance on both the top and bottom surfaces of the double-sided mounted circuit board, improving product consistency and long-term stability.

[0074] The second aspect of this application provides a circuit board manufactured using the circuit board manufacturing method of the first aspect embodiment described above. The sealing and protection structure of the external conductive portion 12 of the circuit board is relatively complete, possessing excellent and stable resistance to salt spray corrosion, strong corrosion resistance, and a long product service life.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for manufacturing a circuit board, characterized in that, include: A blank circuit board is prepared, and an immersion gold metal layer is formed on the surface of the blank circuit board. The surface of the immersion gold metal layer has micropores, and the immersion gold metal layer is divided into an external conductive part and a pad part for soldering electronic components. The blank circuit board is soaked in a sealing agent to fill and seal the micropores on the surface of the immersion gold metal layer. The surface of the external conductive part is covered with an anti-volatile film for shielding and protection. Solder electronic components to the pad portion of the blank circuit board; Remove the anti-volatile film.

2. The circuit board manufacturing method according to claim 1, characterized in that, When covering the surface of the external conductive part with an anti-volatile film, the anti-volatile film is pressed together using a vacuum pressure method.

3. The circuit board manufacturing method according to claim 2, characterized in that, The anti-volatile film lamination process parameters are set as follows: temperature 60℃ to 80℃, pre-pressing time 3 to 10 seconds, molding time 3 to 10 seconds, and molding pressure 15 kg / cm². 2 Up to 25kg / cm 2 .

4. The circuit board manufacturing method according to claim 1, characterized in that, The anti-volatile film is made of high-temperature resistant material.

5. The circuit board manufacturing method according to any one of claims 1 to 4, characterized in that, The process of soldering electronic components to the pad portion of the blank circuit board includes: The electronic components are mounted on the pad portion; A heat insulation cover plate is laid on the surface of the anti-volatile film to block high temperature, and the area where the heat insulation cover plate is laid avoids the electronic components. The electronic components are connected to the pads by a welding process.

6. The circuit board manufacturing method according to claim 5, characterized in that, The provision of a heat-insulating cover plate on the surface of the anti-volatile film includes: The blank circuit board with the electronic components mounted is positioned and placed on the mounting fixture; The heat insulation cover is aligned and fixed to the patch fixture and covers the anti-volatile film area accordingly, so that the heat insulation cover shields the anti-volatile film and avoids the electronic component area.

7. The circuit board manufacturing method according to claim 5, characterized in that, The heat insulation cover is made of high-temperature resistant heat insulation material and is used to block the conduction of welding heat to the anti-volatile membrane.

8. The circuit board manufacturing method according to any one of claims 1 to 4, characterized in that, The circuit board manufacturing method further includes: After removing the anti-volatile film, the surface of the external conductive part is inspected.

9. The circuit board manufacturing method according to any one of claims 1 to 4, characterized in that, After the anti-volatile film is applied to the surface of the external conductive part and before the electronic components are mounted, the bare circuit board is inspected to check the adhesion of the anti-volatile film.

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

Images