Segmented finger chain belt plating method for high speed communication modules

Abstract

The application relates to a gold plating method for a high-speed communication module segmented finger chain belt, which comprises the following steps: providing a carrier plate and an expansion plate; punching a first clamping part on the plate edge of the carrier plate and punching a second clamping part on the expansion plate; carrying out brown oxidation treatment on the punched plate edge of the carrier plate; clamping the expansion plate on the carrier plate to form a composite plate; laminating a copper foil and a prepreg with the composite plate to form a laminated body; placing the laminated body between heated steel plates of a press to carry out hot pressing and curing to form a semi-finished plate; feeding the semi-finished plate into a gold plating tank through a conveying chain belt to carry out full-face gold plating on the gold plating surface of the semi-finished plate; and carrying out subsequent processing on the gold-plated semi-finished plate to obtain a finished high-speed communication module circuit board. The gold plating method combines the expansion plate with the carrier plate, and directly clamps the expansion plate during gold plating, so that the gold plating efficiency is improved, and the product quality is obviously improved.

Description

Technical Field

[0001] This application relates to printed circuit board technology, specifically to a segmented finger chain gold plating method for high-speed communication modules. Background Technology

[0002] "Segmented fingers" refers to the segmented, non-continuous arrangement of metal contacts in the gold finger interface of optical modules and high-speed copper cables. It is mainly used to achieve "power-on timing control" (grounding first, then power supply, then signal) and "insertion and extraction force optimization" during hot plugging and unplugging, so as to reduce signal interference and prevent surge current damage to equipment.

[0003] The processing flow of segmented fingers in a printed circuit board is as follows: outer layer AOI → gold-plated dry film → gold-plated LPI → gold-plated fingers → reverse etch dry film → reverse etch LPI → alkaline etching → film removal → solder mask. After the outer layer pattern is completed, a gold-plated dry film is used to cover the non-gold-plated areas. The gold-plated areas are then uniformly printed with anti-gold plating LPI liquid ink using a screen printing process. Its main function is to isolate the plug-in terminals in segments. During the gold plating process, it acts as an anti-plating bridge with a width of approximately 0.1-0.15mm. While ensuring good conductivity for the entire plug-in terminal, it prevents nickel-gold plating on this part of the copper surface, providing a good etched copper surface for the subsequent alkaline etching process.

[0004] In existing gold plating processes, the industry generally adopts a production method that combines VCP (Vertical Continuous Plating) gold plating lines with chain-type gold plating lines. Due to the influence of the tank depth and chain conveyor method of chain-type gold plating lines, the gold plating operation must be divided into two halves regardless of the size of the product.

[0005] First half processing: Blue adhesive (or water-resistant red tape) is used to mask and attach the other half of the non-gold-plated surface before gold plating on the production line. Second half processing: After gold plating the first half, the masking tape on the other half needs to be removed before gold plating. During half-side processing, the product needs to be clamped on the conveyor belt. Due to the large clamping force, the LPI anti-plating bridge is damaged. During the removal of the masking tape, the tape adheres to and damages or even pulls off the LPI anti-plating bridge. When the second half is gold-plated, due to the damaged anti-plating bridge, the gold layer abnormally deposits onto the copper solder mask surface that should be protected, forming a "gold-adhesive" defect. This prevents the subsequent alkaline etching process from removing the deposited gold layer. The gold layer, acting as an anti-etching layer, protects the underlying copper layer, leaving residual copper solder mask layer, ultimately causing an electrical short circuit at the junction of the two halves. In the existing gold plating process, not only is the plating efficiency low, but product quality is also not guaranteed. Summary of the Invention

[0006] To overcome the above-mentioned defects, this application provides a segmented finger chain gold plating method for high-speed communication modules. This gold plating method combines an expansion board with a carrier board, and the expansion board is directly clamped during gold plating, which not only improves the gold plating efficiency, but also significantly improves the quality of the product.

[0007] The technical solution adopted by this application to solve its technical problem is:

[0008] A method for gold plating segmented finger chain straps for high-speed communication modules includes the following steps:

[0009] Materials preparation: Provide carrier boards with secondary outer layer circuitry that have been processed by previous processes, as well as expansion boards made from scrap boards;

[0010] Forming: A first engaging portion is punched on the edge of the carrier plate, and a second engaging portion matching the first engaging portion is punched on the extension plate;

[0011] Browning: The edges of the punched substrate are browned to enhance their surface adhesion.

[0012] Pre-fixing: The expansion plate is aligned and snapped onto the carrier plate through the first engaging part and the second engaging part to form a composite plate;

[0013] Stacking: According to a preset stacking sequence, copper foil, prepreg, and the composite board are stacked to form a stacked body;

[0014] Lamination: The laminate is placed between heated steel plates of a press and hot-pressed and cured in a vacuum environment, so that the resin in the prepreg flows and cures, thereby combining the copper foil, prepreg and composite board into an integrated semi-finished board.

[0015] Selective gold plating: After necessary intermediate processing of the semi-finished board, the extension board is clamped by a chain clamp and sent into the gold plating tank by a conveyor chain to perform gold plating on the entire surface of the semi-finished board to be gold plated.

[0016] Post-processing: The gold-plated semi-finished board undergoes further processing to obtain the finished high-speed communication module circuit board.

[0017] Optionally, the expansion board is made from scrap substrate with double-sided copper cladding.

[0018] Optionally, the thickness of the carrier plate is D1, the thickness of the extension plate is D2, and the thickness difference between the extension plate and the carrier plate, i.e., D2-D1, is between -0.05mm and +0.025mm.

[0019] Optionally, the width of the expansion plate is 150~220mm, and the length of the expansion plate is the same as the length of the carrier plate.

[0020] Optionally, the first engaging portion is a groove, and the second engaging portion is a protrusion adapted to the groove; or, the first engaging portion is a protrusion, and the second engaging portion is a groove adapted to the protrusion; the groove and the protrusion engage through insertion.

[0021] Optionally, the protrusion includes a main body and at least one wing extending laterally from the main body.

[0022] Optionally, in the pre-fixing process, a hydraulic press is used to quickly press the extension plate and the carrier plate, so that the first engaging part and the second engaging part are engaged and fixed.

[0023] Optionally, the process parameters for pressing with the hydraulic press are: pressure 0.5-3.5 MPa, temperature 130-230°C, and time 1-4 hours.

[0024] Optionally, the size of the prepreg needs to completely cover the composite board, and its length and width should both overflow the composite board by 2-4 mm.

[0025] Optionally, in the forming process, positioning holes are first drilled on the extension plate using a drilling machine, and then the second engaging part is punched out by a punching die. In the browning process, the browning treatment is only applied to the edge area of ​​the plate formed by punching the carrier plate.

[0026] The beneficial effects of this application are as follows: This application innovatively combines an extension board with a carrier plate and utilizes matching interlocking parts to achieve pre-fixation and lamination integration, creating a stable and reliable carrier. This allows the extension board to be directly clamped during subsequent chain-type gold plating, thus solving the industry pain point that traditional fixtures cannot stably clamp or are easily damaged due to the small size and dense gold finger layout of high-speed communication modules. During gold plating, the conveyor belt no longer needs to clamp the effective area within the board; the LPI anti-plating bridge can effectively and completely form an anti-plating function for the segmented areas, reducing the defect rate at the segmented positions from 50% to less than 5%, resulting in significant quality improvement. Using a "segmented finger chain-type" conveyor for full-surface gold plating improves plating efficiency, and the extension board, as the only conductive and mechanical clamping point, ensures uniform current distribution, effectively avoiding problems such as shielding effects, contact point ablation, or uneven plating thickness caused by directly clamping the product body, thereby obtaining high-quality gold fingers with uniform thickness, strong adhesion, and consistent appearance. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the composite panel structure in this application;

[0028] Figure 2 This is a schematic diagram of the carrier plate in this application;

[0029] Figure 3 This is a schematic diagram of the expansion board in this application;

[0030] In the figure: 10-carrier plate, 11-first engaging part, 20-extension plate, 21-second engaging part, 30-composite plate. Detailed Implementation

[0031] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the embodiments described in this application are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such uses of the terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0034] A method for gold plating segmented finger chain straps for high-speed communication modules includes the following steps:

[0035] Material preparation: Provides a carrier board 10 with secondary outer layer circuitry, which has been processed by the previous process, and an expansion board 20 made from scrap boards; the expansion board is made from scrap boards, realizing the direct and high-value recycling of internal scrap materials in PCB production, turning waste into treasure.

[0036] Molding: such as Figure 2 and Figure 3 As shown, a first engaging portion 11 is punched out on the edge of the carrier plate 10, and a second engaging portion 21 that matches the first engaging portion is punched out on the extension plate 20;

[0037] Browning: The edges of the punched substrate 10 are browned to enhance its surface adhesion; this enhances the chemical bonding with the prepreg resin and ensures the reliability of the composite board lamination interface.

[0038] Pre-fixation: such as Figure 1 As shown, the expansion plate 20 is aligned and snapped onto the carrier plate 10 through the first snap-fit ​​part 11 and the second snap-fit ​​part 21 to form a composite plate 30; the expansion plate and the carrier plate are integrated by mechanical snap-fit ​​and lamination, with smooth process connection and stable structure.

[0039] Stacking: According to the preset stacking sequence, copper foil, prepreg and composite plate 30 are stacked to form a stacked body;

[0040] Lamination: The laminate is placed between heated steel plates of a press and hot-pressed and cured in a vacuum environment, so that the resin in the prepreg flows and cures, thereby combining the copper foil, prepreg and composite board 30 into an integrated semi-finished board.

[0041] Selective gold plating: After necessary intermediate processing of the semi-finished board, the extension board 20 is clamped by a chain clamp and sent into the gold plating tank by a conveyor chain. The entire surface of the semi-finished board to be gold-plated is then gold-plated. That is, the electroplating gold processing can plate the entire gold finger in one go, without having to plate it in two halves, thus improving the efficiency of gold plating by 100%.

[0042] Post-processing: The gold-plated semi-finished board undergoes further processing to obtain the finished high-speed communication module circuit board. Optionally, unique APCB-specific souvenirs can be processed on the expansion board 20 to minimize waste disposal costs.

[0043] This application innovatively integrates an extension plate 20 onto a carrier plate 10, utilizing matching interlocking parts to achieve pre-fixation and lamination integration, creating a stable and reliable carrier. This allows the extension plate 20 to be directly clamped during subsequent chain-type gold plating, thus solving the industry pain point that traditional fixtures cannot stably clamp or are easily damaged due to the small size and dense gold finger layout of high-speed communication modules. During gold plating, the conveyor belt no longer needs to clamp the effective area within the plate; the LPI anti-plating bridge can effectively and completely form an anti-plating function for the segmented area, reducing the defect rate at the segmented position from 50% to less than 5%, resulting in significant quality improvement. The use of "segmented finger chain-type" conveyor for full-surface gold plating improves plating efficiency, and the extension plate 20, as the only conductive and mechanical clamping point, ensures uniform current distribution, effectively avoiding problems such as shielding effect, contact point ablation, or uneven plating thickness caused by directly clamping the product body, thereby obtaining high-quality gold fingers with uniform thickness, strong adhesion, and consistent appearance.

[0044] In this application, the expansion board 20 and the carrier board 10 are integrated through mechanical clamping and lamination, resulting in a smooth process transition and a stable structure. This "pre-fixation-lamination" integration step avoids the use of additional adhesives or complex tooling, simplifies operation, reduces human error, and improves the reliability and consistency of the process in mass production. The edges of the carrier board are treated with browning, which enhances the chemical bonding force with the prepreg resin and ensures the reliability of the composite board lamination interface. At the same time, this method avoids mechanically drilling holes in the main body of the product, i.e., the carrier board, or adding process edges as clamping points, thereby maintaining the integrity and mechanical strength of the module board structure and also facilitating the integrity of high-frequency and high-speed signal transmission.

[0045] In this application, the expansion board 20 is made from scrap boards, realizing the direct and high-value recycling of internal scrap materials from PCB production, turning waste into treasure. This not only significantly reduces the material cost of specialized carriers but also aligns with the principles of green manufacturing and circular economy, resulting in significant overall economic benefits. Furthermore, the gold plating method in this application is perfectly compatible with standard punching, laminating, and chain-type electroplating equipment in existing PCB mass production lines, requiring no major modifications. Simultaneously, by adjusting the design of the engaging parts, such as their shape and position, it can be flexibly applied to various high-speed communication module products of different sizes and gold finger layouts, demonstrating strong versatility.

[0046] The expansion board 20 uses double-sided copper-clad substrate scrap. The expansion board 20 uses low-grade scrap, such as FR-4 M1 and M2 grade CCL copper-containing scrap. Secondary processing is performed on scraps cut from ordinary M1 and M2 grade materials, requiring only standard PCB equipment and no additional equipment or materials, thus resulting in low cost.

[0047] The thickness of the carrier plate 10 is D1, and the thickness of the extension plate 20 is D2. The thickness difference between the extension plate 20 and the carrier plate 10, i.e., D2-D1, is between -0.05mm and +0.025mm. The thickness of the extension plate 20 is designed to be basically the same as that of the carrier plate 10, thereby ensuring the flatness of the lamination and ensuring the gold plating effect by having both plates on the same surface.

[0048] Using the extension board 20 can effectively improve the efficiency of gold plating production, changing the original separate plate gold plating to a one-time whole plate gold plating process, eliminating the need for applying and removing adhesive, and reducing the amount of gold plating adhesive work by half.

[0049] The width of the expansion plate 20 is 150~220mm, and the length of the expansion plate 20 is the same as the length of the carrier plate 10. Figure 1 The diagram shows the length and width of the carrier plate 10 and the extension plate 20. This width is the ideal clamping width for the chain conveyor, ensuring that the extension plate 20 can be firmly and stably clamped by existing chain conveyor equipment on the production line. The length is the same as the carrier plate, ensuring that the extension plate 20 can be completely adhered and aligned along one edge of the carrier plate 10 during lamination. After lamination, the two become a solid whole; clamping the extension plate 20 during gold plating is equivalent to firmly holding the entire product, preventing it from shaking or falling off in the plating bath.

[0050] Optionally, such as Figure 2 and Figure 3 As shown, the first engaging portion 11 is a groove, and the second engaging portion 12 is a protrusion adapted to the groove; the groove and the protrusion engage through interlocking. During the pressing of the extension plate onto the carrier plate, the protrusion must be precisely inserted into the groove, with an automatic alignment function to ensure that the two do not shift horizontally. During the hot pressing process of lamination, the resin flow generates lateral force; the engagement of the protrusion and the groove resists lateral shear force, preventing slight slippage between the two layers, thus ensuring the integrity and reliability of the final pressed structure. The groove and the protrusion can be processed in one stamping operation using the same set of punching dies, eliminating the need for additional connecting parts such as screws, glue, or complex processes, resulting in extremely low manufacturing costs, fast assembly speed, and high fault tolerance. Alternatively, the first engaging portion 11 can be a protrusion, and the second engaging portion 21 can be a groove adapted to the protrusion; the groove and the protrusion engage through interlocking.

[0051] The protrusion includes a main body and at least one wing extending laterally from the main body. Designing the protrusion in this shape improves the engagement strength when mated with a corresponding groove, preventing slippage between them. In one possible embodiment, the protrusion has a T-shaped cross-section, comprising a main body and wings extending laterally from the top of the main body; in another possible embodiment, the protrusion has an L-shaped cross-section, comprising a main body and wings extending laterally from the top of the main body; in other possible embodiments, the protrusion has a cross-shaped, arrow-shaped, or other irregular structure. Figure 3 The cross-section of the central protrusion is arrow-shaped.

[0052] In the pre-fixing process, a hydraulic press is used to quickly press the extension plate and the carrier plate together, so that the first engaging part 11 and the second engaging part 21 are engaged and fixed. After pressing, the flatness of the joint between the extension plate and the carrier plate is checked to ensure that the surface is flat and without protrusions.

[0053] The process parameters for hydraulic pressing are: pressure 0.5-3.5 MPa, temperature 130-230℃, and time 1-4 hours. The size of the prepreg must completely cover the composite board, and its length and width must overflow the composite board 30 by 2-4 mm. This provides a sufficient resin source to ensure adequate filling and forms a complete resin "sealing edge" to prevent delamination and moisture intrusion.

[0054] In the forming process, positioning holes are first drilled on the extension plate 20 using a drilling machine, and then the second engaging part 21 is punched out by a punching die. In the browning process, the browning treatment is only applied to the plate edge area formed by punching the carrier plate 10.

[0055] Example 1: A method for gold plating segmented finger chain straps for high-speed communication modules, comprising the following steps:

[0056] S1: Material preparation: Provide a carrier board 10 with secondary outer layer circuitry, which has been processed by the previous process, and an expansion board 20 made from scrap boards; the width of the expansion board 20 is 150-220mm, and the length is the same as that of the carrier board 10; the expansion board 20 is FR-4;

[0057] The preceding processes include tube production → material feeding → inner layer → lamination and punching → inner layer AOI → lamination 1 → browning and copper reduction 1 → laser target burning 1 → drilling blind holes 1 → drilling buried holes → high-cutting grinding 1 → plasma 1 → horizontal PTH 1 → electroplating and leveling 1 → secondary outer layer dry film → secondary outer layer etching → secondary outer layer AOI.

[0058] S2: Molding: such as Figure 2 and Figure 3As shown, a first engaging portion 11 is punched out on the edge of the carrier plate 10. The first engaging portion 11 is an arrow-shaped groove. A second engaging portion 21 that matches the first engaging portion 11 is punched out on the extension plate 20. The second engaging portion 21 is an arrow-shaped protrusion.

[0059] S3: Browning: The edges of the punched substrate 10 are browned to enhance their surface adhesion. After browning, the substrate is transferred to the spare area.

[0060] S4: Pre-fixing: The expansion plate 20 is aligned and snapped onto the carrier plate 10 via the first engaging part 11 and the second engaging part 21 to form a composite plate 30; as shown in the figure Figure 1 As shown, specifically: the protrusion on the extension plate 20 is embedded into the groove on the carrier plate 10, and a hydraulic press is used for fast pressing. After pressing, the flatness of the pressing is checked to ensure that it is flat and without protrusions.

[0061] S5: Stacking: According to the preset stacking sequence, copper foil, prepreg and composite plate 30 are stacked to form a stack; the size of the prepreg is 2-4 mm larger than the composite plate 30 in both length and width directions.

[0062] S6: Lamination: The laminate is placed between the heated steel plates of the press and hot-pressed and cured in a vacuum environment, so that the resin in the prepreg flows and cures, thereby combining the copper foil, prepreg and composite board into an integrated semi-finished board.

[0063] S7: Selective gold plating: After necessary intermediate processing of the semi-finished board, the extension board 20 is clamped by a chain clamp and sent into the gold plating tank by a conveyor chain to perform gold plating on the entire surface of the semi-finished board to be gold plated.

[0064] The intermediate processing includes: browning and copper reduction → laser target burning → drilling blind holes → drilling → high-cutting grinding 2 → plasma → horizontal PTH → electroplating filling → resin plugging → high-cutting grinding 3 → PTH / pulse electroplating → high-cutting grinding → dry film → positive film etching → intermediate AOI → impedance measurement → solder mask → gold plating dry film → LPI gold plating pretreatment.

[0065] S8: Post-processing: Further processing is carried out on the gold-plated semi-finished board to obtain the finished high-speed communication module circuit board.

[0066] The subsequent processing technology includes: dry film 2 → before LPI reverse etching → alkaline etching → film removal → positive wet film → selective dry film → solder resist baking → electroless gold → selective film removal → text → plate lifting → hydrogel film laying → laser target → forming 1 → impedance measurement → blind fishing 1 → blind fishing → forming → beveling → V-CUT → testing → forming sealing agent → final inspection → packaging.

[0067] It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application shall be determined by the appended claims.

Claims

1. A method for gold plating segmented finger chain straps for high-speed communication modules, characterized in that: Includes the following steps: Materials preparation: Provide a carrier board (10) with sub-outer layer circuitry that has been processed by the previous process, and an extension board (20) made from scrap boards. Forming: A first engaging part (11) is punched on the edge of the carrier plate (10), and a second engaging part (21) matching the first engaging part is punched on the extension plate (20). Browning: The edges of the punched substrate (10) are browned to enhance their surface bonding strength; Pre-fixing: The expansion plate (20) is aligned and snapped onto the carrier plate (10) through the first engaging part (11) and the second engaging part (21) to form a composite plate (30). Stacking: According to the preset stacking order, copper foil, prepreg and composite plate (30) are stacked to form a stack; Lamination: The laminate is placed between the heated steel plates of the press and hot-pressed in a vacuum environment to allow the resin in the prepreg to flow and solidify, thereby combining the copper foil, prepreg and composite board (30) into an integrated semi-finished board. Selective gold plating: After necessary intermediate processing of the semi-finished board, the extension board (20) is clamped by a chain clamp and sent into the gold plating tank by a conveyor chain to perform gold plating on the entire surface of the semi-finished board to be gold plated. Post-processing: The gold-plated semi-finished board undergoes further processing to obtain the finished high-speed communication module circuit board.

2. The high-speed communication module segmented finger chain gold plating method according to claim 1, characterized in that: The expansion board (20) is made from double-sided copper-clad substrate waste.

3. The high-speed communication module segmented finger chain gold plating method according to claim 1, characterized in that: The thickness of the carrier plate (10) is D1, the thickness of the extension plate (20) is D2, and the thickness difference between the extension plate (20) and the carrier plate (10), namely D2-D1, is between -0.05mm and +0.025mm.

4. The high-speed communication module segmented finger chain gold plating method according to claim 1, characterized in that: The width of the expansion plate (20) is 150~220mm, and the length of the expansion plate (20) is the same as the length of the carrier plate (10).

5. The high-speed communication module segmented finger chain gold plating method according to claim 1, characterized in that: The first engaging part (11) is a groove, and the second engaging part (12) is a protrusion adapted to the groove; or, the first engaging part (11) is a protrusion, and the second engaging part (21) is a groove adapted to the protrusion; the groove and the protrusion are engaged by insertion.

6. The high-speed communication module segmented finger chain gold plating method according to claim 5, characterized in that: The protrusion includes a main body and at least one wing extending laterally from the main body.

7. The high-speed communication module segmented finger chain gold plating method according to claim 1, characterized in that: In the pre-fixing process, a hydraulic press is used to quickly press the extension plate and the carrier plate so that the first locking part (11) and the second locking part (21) are locked together.

8. The high-speed communication module segmented finger chain gold plating method according to claim 7, characterized in that: The process parameters for pressing using the hydraulic press are: pressure 0.5-3.5 MPa, temperature 130-230℃, and time 1-4 hours.

9. The high-speed communication module segmented finger chain gold plating method according to claim 1, characterized in that: The size of the prepreg must completely cover the composite board, and its length and width must both overflow 2-4 mm relative to the composite board (30).

10. The high-speed communication module segmented finger chain gold plating method according to claim 1, characterized in that: In the forming process, a positioning hole is first drilled on the extension plate (20) using a drilling machine, and then the second engaging part (21) is punched out by a punch die. In the browning process, the browning treatment is only applied to the plate edge area formed by punching the carrier plate (10).

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