Method for processing bevel edge of golden finger area of printed circuit board

Abstract

The invention relates to a method for processing a bevel edge of a golden finger area of a printed circuit board, which sequentially comprises the following steps of: A, resistance welding and windowing: windowing a golden finger body and an adjacent lead area in a resistance welding process, and exposing a copper surface of the area; b, conducting wire area etching: completely removing the copper layer of the adjacent conducting wire area on the outer side of the golden finger body through a graphical etching process; and C, bevel edge forming: performing bevel edge cutting along the copper-free isolation strip formed by etching in the lead area, wherein the cutting boundary ends at the copper-free isolation strip and is far away from the golden finger body. The metal exposure risk during bevel edge cutting is thoroughly eliminated through the copper-free isolation strip, and an electrochemical migration path is blocked; no metal contact exists in the whole cutting process, conductive chippings are completely eradicated, and the hidden danger of short circuit in a high-frequency plugging scene is solved; the isolation belt design is compatible with conventional equipment precision, and the process error-tolerant rate and reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to printed circuit board manufacturing technology, in particular to a bevel processing method of a gold finger area, especially suitable for gold finger protection in high-frequency and high-speed scenarios. BACKGROUND

[0002] In the field of printed circuit board manufacturing, there are two interrelated technical bottlenecks in gold finger bevel processing: first, traditional bevel cutting operation is easy to damage the wire area outside the gold finger, resulting in the exposure of the copper layer or nickel layer inside the substrate to the cutting surface. This metal exposure not only damages the insulating protective layer, but also causes electrochemical migration in a humid and hot environment. Second, when the bevel position is left with copper layer of the wire, the mechanical friction force borne by the circuit board during plugging will continuously scrape the metal edge, generating micron-level conductive debris. These debris may fall into adjacent circuit channels, causing unpredictable intermittent short circuit failures.

[0003] Existing improvement schemes mainly focus on improving processing accuracy, such as using high-resolution optical positioning systems or nanoscale cutting tools. However, such methods cannot change the physical fact that the metal layer objectively exists in the bevel area: as long as the copper layer of the wire extends to the cutting area, the risk of copper exposure cannot be eliminated; as long as the metal is in contact with the cutter, copper debris cannot be avoided. Especially in high-frequency plugging scenarios (such as hot-pluggable accelerator cards in data centers), this problem will cause the connector life to be significantly lower than the design expectation. SUMMARY

[0004] Therefore, the present application provides a bevel processing method for the gold finger area of a printed circuit board, which completely eliminates the risk of metal exposure during bevel cutting by using a copper-free isolation band, blocks the electrochemical migration path, has no metal contact during cutting, eliminates the generation of conductive debris, and solves the short circuit hazard in high-frequency plugging scenarios. The isolation band design is compatible with the accuracy of conventional equipment, improving the process fault tolerance and reliability.

[0005] The purpose of the present application is achieved by the following technical solutions: A bevel processing method for the gold finger area of a printed circuit board, comprising the following sequential steps: Step A, solder mask windowing: windowing the gold finger body and its adjacent wire area in the solder mask process to expose the copper surface of the area; Step B, wire area etching: completely removing the copper layer of the adjacent wire area outside the gold finger body through a patterned etching process; Step C, bevel forming: bevel cutting along the copper-free isolation band formed by the wire area etching, and the cutting boundary terminates at the copper-free isolation band and is away from the gold finger body.

[0006] The systematic cooperation of the three core steps of solder mask windowing, wire area etching, and bevel forming fundamentally solves two historical problems in the field of gold finger bevel processing. First, the solder mask windowing step accurately exposes the copper surface of the gold finger body and the adjacent wire area, creating an operating window for subsequent etching and ensuring the processability of the target area. Second, the wire area etching step completely removes the copper layer of the wire outside the gold finger body, forming a metal-free physical isolation band. This design eliminates the possibility of metal exposure during bevel processing from a material level, directly blocking the cause chain of copper and nickel exposure. Finally, the bevel cutting step is strictly limited within the copper-free isolation band, and the cutting boundary maintains a safe distance from the gold finger body. This spatial isolation mechanism ensures zero contact between the tool and the metal layer, avoiding cutting damage and preventing plugging friction.

[0007] The synergistic innovation of the three-step process brings multiple technical benefits. The creation of the copper-free isolation band changes the bevel processing area from a traditional metal-substrate mixed area to a pure-substrate safe area, and the processing process does not generate metal debris. The design of the cutting boundary away from the gold finger body provides a buffer space for processing errors, significantly improving the process fault tolerance. In addition, this method eliminates the absolute dependence on specific processing precision, and only needs to ensure the etching completeness and cutting positioning accuracy to be compatible with different equipment conditions, reducing the industrialization threshold. The final gold finger structure breaks the transmission path of external force in the copper-free isolation band when plugging, fundamentally eliminating the short circuit risk caused by copper debris falling, especially suitable for high-reliability scenarios.

[0008] Preferably, the windowing range of the wire area in step A solder mask windowing covers the gold finger body and extends outward.

[0009] By extending the solder mask windowing range to the outside of the gold finger body, sufficient working area is ensured for subsequent etching operations. The extended windowing design provides a larger process window, allowing the etching step to completely cover the target area where the copper layer needs to be removed, avoiding etching residues caused by insufficient windowing. At the same time, this extended range can adapt to different sizes of gold finger layout, enhancing the method's versatility. The reservation of the extended area also reduces the exposure alignment accuracy requirement, improving process stability.

[0010] Preferably, step A solder mask windowing includes: applying solder mask ink to the entire board and pre-baking; using a windowing negative film that covers the gold finger body and adjacent wires for exposure; removing the uncured ink in the windowing area after development.

[0011] The sub-step defines the standard industrialized implementation path of solder mask windowing. Whole-board coating ensures uniformity of ink coverage, and the pre-baking step optimizes the physical state of the ink, laying the foundation for subsequent exposure. Exposure with a specially designed windowing negative can precisely define the windowing pattern of the gold finger body and adjacent wires, ensuring the integrity of the copper surface exposure in critical areas. After development, the operation of selectively removing unhardened ink forms a clear copper surface exposure area, providing an accurate processing reference for the etching process and reducing process deviations.

[0012] Preferably, after the solder mask windowing of step A, a local gold plating process is further included: forming a plating-resistant layer on the exposed copper surface area, leaving only a gold-plated window in the gold finger body area; performing gold plating after covering the non-gold-plated area with a peelable protective layer; and removing the protective layer and the plating-resistant layer.

[0013] The local gold plating process achieves selective gold plating of the gold finger through multiple protection mechanisms. The formation of the plating-resistant layer prevents electroplating in non-target areas, combined with the physical coverage of the non-gold-plated area by the peelable protective layer, forming a double protection system to ensure that the gold plating process only acts on the gold finger body. This design avoids contamination of the surrounding area by the electroplating solution, ensuring the clarity of the gold plating layer edge. The application of the peelable protective layer facilitates subsequent quick removal, reducing the risk of damage to the substrate and improving the stability of the gold plating quality.

[0014] Preferably, step B wire area etching includes: forming a photoresist layer on the whole board; performing pattern transfer with a windowing negative matching the wire etching area; and after development, etching the exposed copper layer and removing the resist layer.

[0015] This step provides a standardized implementation scheme for the etching process. The formation of the photoresist layer establishes a temporary protective barrier, and its patternable characteristics facilitate accurate control of the etching area. Customized windowing negatives are used for pattern transfer to ensure that the etching range perfectly matches the target wire area, avoiding over-etching or under-etching. After development, the exposed copper layer is directly etched, and the operation path is simple and efficient. Finally, removing the resist layer restores the surface state of the substrate, creating a clean interface for subsequent bevel processing.

[0016] Preferably, in step C bevel forming, there is a safety isolation zone between the cutting boundary and the gold finger body.

[0017] The design of the safety isolation zone creates an absolute safety zone between the gold finger body and the cutting boundary. This gap forms a physical buffer zone, completely isolating the bevel processing tool from the gold finger body and eliminating the risk of processing damage. In subsequent plug-in and plug-out operations, the gap can accommodate micro-deformation without transmitting stress to the gold finger, reducing the probability of plating layer detachment caused by mechanical stress. The existence of the gap also reduces the stringent requirements for bevel cutting precision, improving process robustness.

[0018] Preferably, the cutting trajectory of the bevel forming in step C is entirely within the copper-free isolation band formed by etching the conductor area.

[0019] Strictly confining the cutting trajectory within a copper-free isolation zone is the core guarantee for solving the problem of metal exposure. This design ensures that the cutting operation never comes into contact with any metal layer, fundamentally eliminating copper and nickel exposure. The homogeneous nature of the copper-free substrate makes the cutting process stable and controllable, avoiding uneven cuts caused by differences in material hardness. At the same time, the debris generated from cutting the pure substrate is an insulating material, eliminating the risk of short circuits caused by conductive debris.

[0020] Preferably, the formation of the resist layer includes: printing resist ink only at the gold finger location, and exposing and developing it using a windowed film covering the gold finger area.

[0021] Precise printing of resist ink onto the gold fingers and control of the exposure and development process using a windowed film over the gold finger area significantly optimizes the accuracy of resist layer formation. Local printing of resist ink reduces chemical consumption and lowers production costs. Windowed film exposure and development ensure clear boundaries of the resist pattern, preventing deviations in the gold plating window size. This technology improves the reliability of gold plating area definition, preventing plating diffusion caused by accidental exposure of non-target areas. The targeted application of resist ink also shortens the processing time of subsequent stripping processes, improving production line turnover efficiency. Overall process control enhances the stability of the gold plating position, ensuring consistent electrical performance of the gold fingers.

[0022] Preferably, the wire etching area includes: a wire extension segment on the outer side of the gold finger body, the length of which is greater than the width of the gold finger.

[0023] The etched area extends beyond the gold finger body and exceeds the width of the gold finger. This design creates ample copper-free isolation space, providing a safe operating area for bevel cutting. The redundant length of the extension compensates for potential edge effects during the etching process, ensuring complete removal of the target copper layer. The longer etched area reduces the stringent requirements for cutting positioning accuracy, improving process tolerance. The design, with a length greater than the width of the gold finger, accommodates different gold finger layouts, enhancing method versatility. This feature also optimizes stress distribution, keeping the insertion and extraction stress points away from functional areas, reducing the risk of metal fatigue. The spatial buffering effect of the extension further isolates the impact of processing stress on the gold finger body.

[0024] Preferably, step C, bevel forming, includes: the bevel cutting height covers the gold finger conductor area, and the cutting boundary maintains a safe distance from the gold finger body.

[0025] A dual positioning mechanism ensures the safety of bevel machining. The cutting height covering the conductor area ensures complete removal of the original metal conductor, eliminating the risk of residual copper. The reserved safety distance creates a physical isolation buffer, completely preventing contact between the cutting tool and the gold finger body. This combined design guarantees thorough machining while providing operational safety margins, significantly reducing the probability of accidental damage. The reserved safety distance also compensates for equipment mechanical errors, improving process robustness. The coordinated control of the cutting height and safety distance ensures the bevel cut remains within an absolutely safe area, preventing exposed copper or nickel. This technical solution is particularly suitable for ensuring reliability in high-frequency insertion and removal scenarios.

[0026] The advantages of this invention compared to the prior art are: This solution achieves a fundamental improvement in the processing of beveled edges of gold fingers by reconstructing the process chain and material distribution: 1. Systematic solutions to the problem of metal exposure The solder mask opening step establishes a precise operating window for subsequent etching processes. By exposing the copper surface of the target area, it ensures that the etching medium can fully contact the metal layer to be removed.

[0027] The etching step in the conductor area completely removes the metal structure outside the gold finger body, creating a pure substrate isolation band in physical space. This isolation band acts as an insulating barrier, completely separating the beveled processing area from the metal layer coverage, thus blocking the path of exposed copper and nickel at the source.

[0028] The bevel forming process strictly confines the cutting trajectory within the copper-free substrate isolation zone, ensuring zero contact between the tool and the metal layer throughout the entire process. The design of keeping the cutting boundary away from the gold finger body further forms a permanent physical isolation zone, preventing metal exposure during processing or use.

[0029] 2. Effective blocking of the copper scrap generation mechanism The copper-free substrate isolation band formed by etching the conductor area transforms the beveled processing object from a traditional "metal-resin composite" into a "homogeneous insulator." The cutting process only produces non-conductive resin debris, completely eliminating the source of conductive contamination.

[0030] The establishment of a safety isolation zone ensures that the gold finger body is removed from the stress transmission path during insertion and removal. When external forces act on the isolation strip, they are absorbed and dispersed by the insulating material, preventing fatigue peeling of the metal layer and significantly reducing the probability of debris generation.

[0031] 3. Substantial improvement in process robustness The three-step process design reduces the absolute dependence on the precision of individual operations: solder mask opening only needs to ensure full exposure of the copper surface, wire etching is based on the complete removal of the copper layer, and bevel cutting relies on the copper-free isolation band to provide a wide operating window. This fault-tolerant mechanism is compatible with processing equipment of different precision levels.

[0032] The introduction of the isolation strip restructures the structural reliability model. Traditional processes rely on coating strength and interfacial adhesion to resist damage, while this solution optimizes the spatial distribution of materials, making reliability no longer entirely dependent on the ultimate performance of materials, thus broadening the range of substrate and coating options.

[0033] 4. Enhanced adaptation to high-frequency application scenarios Copper-free isolation strips eliminate parasitic capacitance interference sources in the beveled region, reducing edge field distortion in high-speed signal transmission.

[0034] The safety isolation zone prevents random short circuits caused by metal debris, improving signal integrity in high-density circuit environments.

[0035] The cut surface of a homogeneous substrate provides a more stable dielectric constant distribution, reducing the risk of impedance discontinuity. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 Design drawing for solder resist window exposure film (showing the window graphic design of the gold finger and adjacent conductor areas).

[0038] Figure 2 This is a schematic diagram showing the exposed copper surface after solder mask development (showing the exposed copper surface of the gold finger body and the extension of the conductor).

[0039] Figure 3 A schematic diagram of resist ink positioning printing (showing the precise printing position of resist ink in the gold finger area).

[0040] Figure 4 This is a schematic diagram of the exposure process for resist coating (showing the exposure control of the gold finger area on the film with full-area windowing).

[0041] Figure 5 This is a close-up of the exposed state of the gold fingers after resist plating and development (close-up of the copper surface of the gold fingers after the resist plating layer has been removed).

[0042] Figure 6 This is a schematic diagram of the removal of the protective layer after gold plating (showing the gold plating structure after the protective film is peeled off and the resist layer is removed).

[0043] Figure 7 This is a schematic diagram of the transfer of the etched pattern of the conductor (showing the matching relationship between the etched window film and the conductor extension).

[0044] Figure 8 This is a structural diagram after the conductor is etched and developed (showing the exposed state of the copper layer after the resist layer of the conductor extension is removed).

[0045] Figure 9 This is a schematic diagram of the formation of a copper-free substrate isolation band (showing the metal-free substrate band structure formed after etching).

[0046] Figure 10 This is a diagram showing the surface condition after the resist film has been removed (showing the clean substrate surface and the boundary of the isolation strip).

[0047] Figure 11 This is the final structural diagram of the beveled edge forming. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0050] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of the embodiments of this application, it should be understood that the terms "upper," "lower," "left," "right," "vertical," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. 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.

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0052] The technical solutions in this application will now be described with reference to the accompanying drawings. Example 1

[0053] This embodiment provides a method for processing the beveled edge of the gold finger area of ​​a printed circuit board, including the following sequential steps: Solder mask opening: During the solder mask process, an opening is made in the gold finger body and its adjacent conductor area to expose the copper surface of that area; Etching of the conductor area: The copper layer in the area adjacent to the conductor on the outside of the gold finger body is completely removed through a patterned etching process; Beveled edge forming: The copper-free isolation band formed by etching along the conductor area is beveled and cut. The cutting boundary ends at the copper-free isolation band and is far away from the gold finger body.

[0054] By systematically coordinating three core steps—solder mask opening, conductor area etching, and beveling—two historical challenges in the beveling of gold fingers are fundamentally solved. First, the solder mask opening step precisely exposes the copper surface of the gold finger body and adjacent conductor areas, creating an operating window for subsequent etching and ensuring the processability of the target area. Second, the conductor area etching step completely removes the copper layer of the conductors on the outside of the gold finger body, forming a metal-free physical isolation zone. This design eliminates the possibility of metal exposure during beveling at the material level, directly blocking the causal chain of exposed copper and nickel. Finally, the beveling cutting step is strictly confined to the copper-free isolation zone, and the cutting boundary maintains a safe distance from the gold finger body. This spatial isolation mechanism ensures zero contact between the tool and the metal layer, avoiding both cutting damage and insertion / removal friction.

[0055] The synergistic innovation of the three-step process brings multiple technological benefits. The creation of the copper-free isolation band transforms the bevel processing area from a traditional metal-substrate hybrid zone into a pure substrate safe zone, eliminating metal debris during processing. The design of the cutting boundary being far from the gold finger body provides a buffer space for processing errors, significantly improving process tolerance. Furthermore, this method eliminates the absolute dependence on specific processing precision; it only needs to ensure thorough etching and accurate cutting positioning to be compatible with different equipment conditions, lowering the industrialization threshold. The final gold finger structure, when subjected to insertion and extraction forces, has its external force transmission path interrupted at the copper-free isolation band, fundamentally eliminating the risk of short circuits caused by copper debris shedding, making it particularly suitable for high-reliability scenarios.

[0056] In this embodiment, the opening range of the conductor area in the solder mask opening covers the gold finger body and extends outward therefrom.

[0057] By extending the solder mask opening to the outside of the gold finger body, sufficient working area is ensured for subsequent etching operations. The extended opening design provides a larger process window, allowing etching steps to completely cover the target area where the copper layer needs to be removed, avoiding etching residue caused by insufficient opening. Simultaneously, this extension range can accommodate gold finger layouts of different sizes, enhancing method versatility. The reserved extended area also reduces the requirements for exposure alignment accuracy, improving process stability.

[0058] In this embodiment, the solder resist windowing includes: coating the entire board with solder resist ink and pre-baking; exposing the windowed film covering the gold finger body and adjacent conductors; and removing the uncured ink in the windowed area after development.

[0059] This step-by-step approach defines a standard industrial implementation path for solder mask windowing. Full-board coating ensures uniform ink coverage, while the pre-baking step optimizes the ink's physical state, laying the foundation for subsequent exposure. Using a specifically designed windowed film for exposure precisely defines the windowed pattern of the gold fingers and adjacent conductors, ensuring the integrity of copper exposure in critical areas. The selective removal of uncured ink after development creates a clear copper exposure area, providing a precise machining reference for the etching process and reducing process deviations.

[0060] In this embodiment, after the solder mask window is opened, a partial gold plating process is also included: a resist layer is formed on the exposed copper surface area, and only the gold plating window of the gold finger body area is retained; after covering the non-gold plating area with a peelable protective layer, gold plating is performed; and the protective layer and resist layer are removed.

[0061] The selective gold plating process employs multiple protection mechanisms to achieve selective gold plating on the gold fingers. A resist layer prevents plating on non-target areas, while a peelable protective layer physically covers non-gold-plated areas, creating a dual protection system to ensure the gold plating process only affects the gold finger itself. This design prevents plating solution from contaminating surrounding areas, ensuring the clarity of the gold plating layer edges. The application of the peelable protective layer facilitates rapid removal, reducing the risk of damage to the substrate and improving the stability of the gold plating quality.

[0062] In this embodiment, the etching of the conductor area includes: forming a photoresist layer on the entire board; performing pattern transfer using a windowed film that matches the conductor etching area; etching the exposed copper layer after development and removing the photoresist layer.

[0063] This step provides a standardized implementation scheme for the etching process. The formation of the photoresist layer establishes a temporary protective barrier, and its patternable nature facilitates precise control of the etching area. A custom-designed windowed film is used for pattern transfer, ensuring that the etching range perfectly matches the target conductor area and avoiding over-etching or under-etching. After development, the exposed copper layer is etched directly, resulting in a simple and efficient operation path. Finally, removing the photoresist layer restores the substrate surface condition, creating a clean interface for subsequent beveling.

[0064] In this embodiment, a safety isolation zone exists between the cutting boundary and the gold finger body during the bevel forming process.

[0065] The safety isolation zone design creates an absolute safety zone between the gold finger body and the cutting boundary. This gap forms a physical buffer, completely isolating the bevel machining tool from contact with the gold finger body and eliminating the risk of machining damage. During subsequent insertion and removal operations, this gap can accommodate micro-deformation without transferring stress to the gold finger, reducing the probability of plating peeling due to mechanical stress. The existence of the gap also reduces the stringent requirements for bevel cutting accuracy, improving process robustness.

[0066] In this embodiment, the cutting trajectory formed by the bevel is entirely within the copper-free isolation band formed by etching the conductor area.

[0067] Strictly confining the cutting trajectory within a copper-free isolation zone is the core guarantee for solving the problem of metal exposure. This design ensures that the cutting operation never comes into contact with any metal layer, fundamentally eliminating copper and nickel exposure. The homogeneous nature of the copper-free substrate makes the cutting process stable and controllable, avoiding uneven cuts caused by differences in material hardness. At the same time, the debris generated from cutting the pure substrate is an insulating material, eliminating the risk of short circuits caused by conductive debris.

[0068] In this embodiment, the formation of the resist layer includes: printing resist ink only at the gold finger location, and exposing and developing a windowed film covering the gold finger area.

[0069] Precise printing of resist ink onto the gold fingers and control of the exposure and development process using a windowed film over the gold finger area significantly optimizes the accuracy of resist layer formation. Local printing of resist ink reduces chemical consumption and lowers production costs. Windowed film exposure and development ensure clear boundaries of the resist pattern, preventing deviations in the gold plating window size. This technology improves the reliability of gold plating area definition, preventing plating diffusion caused by accidental exposure of non-target areas. The targeted application of resist ink also shortens the processing time of subsequent stripping processes, improving production line turnover efficiency. Overall process control enhances the stability of the gold plating position, ensuring consistent electrical performance of the gold fingers.

[0070] In this embodiment, the wire etching area includes: a wire extension segment on the outside of the gold finger body, the length of which is greater than the width of the gold finger.

[0071] The etched area extends beyond the gold finger body and exceeds the width of the gold finger. This design creates ample copper-free isolation space, providing a safe operating area for bevel cutting. The redundant length of the extension compensates for potential edge effects during the etching process, ensuring complete removal of the target copper layer. The longer etched area reduces the stringent requirements for cutting positioning accuracy, improving process tolerance. The design, with a length greater than the width of the gold finger, accommodates different gold finger layouts, enhancing method versatility. This feature also optimizes stress distribution, keeping the insertion and extraction stress points away from functional areas, reducing the risk of metal fatigue. The spatial buffering effect of the extension further isolates the impact of processing stress on the gold finger body.

[0072] In this embodiment, the bevel forming includes: the bevel cutting height covers the gold finger wire area, and the cutting boundary maintains a safe distance from the gold finger body.

[0073] A dual positioning mechanism ensures the safety of bevel machining. The cutting height covering the conductor area ensures complete removal of the original metal conductor, eliminating the risk of residual copper. The reserved safety distance creates a physical isolation buffer, completely preventing contact between the cutting tool and the gold finger body. This combined design guarantees thorough machining while providing operational safety margins, significantly reducing the probability of accidental damage. The reserved safety distance also compensates for equipment mechanical errors, improving process robustness. The coordinated control of the cutting height and safety distance ensures the bevel cut remains within an absolutely safe area, preventing exposed copper or nickel. This technical solution is particularly suitable for ensuring reliability in high-frequency insertion and removal scenarios. Example 2

[0074] This embodiment uses the processing of a gold finger structure as an example, and includes the following sequential steps: I. Weld Resistance Window Processing 1. Apply liquid photosensitive solder resist ink evenly to the entire surface of the printed circuit board, and immediately perform a pre-baking treatment after coating to remove solvent components; 2. As attached Figure 1 As shown, an exposure film is prepared using a photoplotter. A fully open window pattern is designed in the gold finger body and the adjacent conductor area (green area in the figure). This open window area blocks ultraviolet light from initiating a polymerization reaction during the exposure process. 3. As attached Figure 2 As shown, the unpolymerized ink is removed after treatment with developer, so that the copper surface is fully exposed in the windowed area; 4. Perform a thermosetting process to fully polymerize the retained ink. At this point, the gold finger body and its outer conductor extension (approximately 1.5 mm in length) form a continuous exposed copper surface, with the edge retaining a substrate isolation area.

[0075] II. Selective Gold Plating 1. As attached Figure 3 As shown, resist ink is precisely printed in the solder resist window area, focusing on covering the area outside the gold finger body; 2. As attached Figure 4 As shown, a second exposure process using a full-area windowed exposure film (green area in the diagram) is performed to block the photochemical reaction in the gold finger area; 3. As attached Figure 5 As shown, after development, the resist layer on the gold finger body is completely removed, and the copper surface is clean and exposed. 4. Use a chemically resistant, peelable protective film to completely cover the non-gold finger areas; 5. Perform an electrochemical gold plating process, depositing a gold layer only on the exposed copper surface of the gold fingers; 6. As attached Figure 6 As shown, the protective film is mechanically peeled off, and the residual resist layer is removed with an alkaline solution.

[0076] III. Wire Etching Process 1. A negative photoresist film is laminated over the entire board, and vacuum lamination is used to ensure no air bubbles adhere. 2. As attached Figure 7 As shown, a special windowed exposure film for etching (green area in the diagram) is used for pattern transfer; 3. As attached Figure 8 As shown, after development with sodium carbonate solution, the resist layer on the outer conductor extension section (approximately 1.5 mm in length) of the gold finger is completely removed, and the copper layer is fully exposed. 4. As attached Figure 9 As shown, the copper chloride etching solution precisely removes the exposed copper layer, forming a metal-free substrate strip; 5. As attached Figure 10 As shown, potassium hydroxide solution completely removes the resist film.

[0077] IV. Bevel forming process 1. Complete the CNC milling machining of the circuit board outline; 2. Use a diamond grinding wheel to make a 30° bevel cut along the edge of the plate; 3. The cutting trajectory completely covers the solder resist ink layer of the original conductor area; 4. Maintain a safe distance (approximately 0.25mm) between the cutting termination point and the edge of the gold finger body. The finished product should look like the attached image. Figure 11 As shown; 5. The optical inspection system monitors the cutting path in real time to ensure zero damage to the gold finger structure.

[0078] V. Final Structural Features The completed bevel structure includes: 1. The surface of the gold finger body has a complete gold plating layer; 2. A continuous outer copper-free substrate isolation strip (approximately 1.5mm wide); 3. The beveled cut completely penetrates the isolation zone area; 4. A clear physical isolation zone is formed between the inner edge of the incision and the gold finger.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for processing the beveled edge of the gold finger area of ​​a printed circuit board, characterized in that, Includes the following sequential steps: Step A, Solder Mask Opening: In the solder mask process, an opening is made in the gold finger body and its adjacent conductor area to expose the copper surface of the area; Step B, Conductor Area Etching: The copper layer in the adjacent conductor area on the outside of the gold finger body is completely removed through a patterned etching process. Step C, Beveled Edge Forming: Bevel the copper-free isolation strip formed in Step B, with the cutting boundary ending at the copper-free isolation strip and away from the gold finger body.

2. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 1, characterized in that, The windowed area of ​​the conductor region described in step A covers the gold finger body and extends outward therefrom.

3. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 1, characterized in that, Step A includes: The entire board is coated with solder resist ink and pre-baked. Exposure is performed using a windowed film that covers the gold finger body and adjacent conductors; After development, remove the uncured ink from the windowed area.

4. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 1, characterized in that, Step A is followed by: Partial gold plating process: A resist layer is formed on the exposed copper surface area, leaving only the gold-plated window in the gold finger body area intact; Gold plating is performed after a peelable protective layer covers the non-gold-plated areas; Remove the protective layer and the resist layer.

5. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 1, characterized in that, Step B includes: A photosensitive anti-corrosion layer is formed on the entire board; Pattern transfer is performed using a windowed film that matches the etched area of ​​the conductor; After development, the exposed copper layer is etched and the resist layer is removed.

6. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 1, characterized in that, There is a safety isolation zone between the cutting boundary and the gold finger body described in step C.

7. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 1, characterized in that, The oblique cutting trajectory in step C is completely within the copper-free isolation zone formed in step B.

8. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 4, characterized in that, The formation of the resist layer includes: printing resist ink only at the gold finger location, and exposing and developing it using a windowed film covering the gold finger area.

9. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 5, characterized in that, The wire etching area includes: a wire extension section on the outside of the gold finger body, the length of which is greater than the width of the gold finger.

10. The method for processing the beveled edge of the gold finger area of ​​a printed circuit board according to claim 1, characterized in that, The bevel forming includes: the bevel cutting height covers the gold finger conductor area, and the cutting boundary maintains a safe distance from the gold finger body.

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