High-speed signal wiring structure of soft and hard combination board with high anti-interference and low parasitic function

Abstract

The utility model belongs to the technical field of electronic circuit design, concretely relates to the soft and hard combination board high -speed signal wiring structure with high anti -interference low parasitic function, the corner section of two differential signal lines in differential line group is all structured as the arc section of whole section smooth circular arc transition and circular arc curvature continuous no mutation, the width of differential signal line is kept consistent along the arc section, reduces the signal reflection at the corner, strictly controls the length error of differential signal line in group and the length error of differential signal line between groups, realizes double -deck level equal length management and control, realizes differential pair high precision matching and multi -channel global time sequence synchronization inside simultaneously, guarantees multi -way GTX parallel transmission no data misplacement, combines the middle layer wiring, and the adjacent layer lays the complete continuous ground layer, and further improves the anti -interference capacity, the whole layer does not cross the ground segmentation, and the reflow loop is complete and stable, forms the soft and hard combination board high -speed signal wiring structure with high anti -interference low parasite function.

Description

Technical Field

[0001] This utility model belongs to the field of electronic circuit design technology, specifically relating to a high-speed signal wiring structure for a rigid-flex PCB with high anti-interference and low parasitic functions. Background Technology

[0002] The existing rigid-flex PCB high-speed signal wiring structure has the following problems: 1. In the existing technology, the routing of differential signal lines at the corners often adopts a 45° bend routing scheme. The corners are prone to impedance changes, which can generate high-frequency reflection noise. Some high-speed wiring commonly uses a simple arc structure. The arc curvature is discontinuous and the routing width varies greatly. It is prone to fluctuation at high frequencies, resulting in poor signal integrity.

[0003] 2. In existing technologies, wiring only controls the length error within differential pairs, but does not constrain the length error between pairs. This is especially important for GTX high-speed differential signals with strict timing requirements.

[0004] 3. Existing technology places the traces on the surface layer, but the copper thickness of the surface layer is usually ≥1oz, resulting in larger parasitic parameters.

[0005] 4. In existing rigid-flex boards, when repeatedly bent, the wiring is not optimized, the impedance is discontinuous, and the reference plane is easily crossed. The return path is forced to detour, resulting in increased EMI radiation. Utility Model Content

[0006] The purpose of this invention is to provide a high-speed signal wiring structure for a rigid-flex PCB with high anti-interference and low parasitic functions to solve the problems in the prior art, such as impedance sudden change at corners causing high-frequency reflection noise, easy fluctuation at high frequencies, poor signal integrity, and large parasitic parameters.

[0007] This utility model provides a high-speed signal cabling structure for a rigid-flex PCB with high anti-interference and low parasitic functions, including: A flexible board, which is connected to a rigid board, and a soft-hard transition zone is provided between the flexible board and the rigid board; At least two sets of differential line groups, each set of differential line groups includes two differential signal lines, the differential signal lines are arranged on the flexible board and routed to the rigid board through the flexible-hard transition area; The corner segments of the two differential signal lines in the differential line group are constructed as a smooth arc transition with continuous and abrupt changes in arc curvature, and the trace width of the differential signal line remains consistent along the arc segment.

[0008] According to this scheme, the corner adopts a smooth arc with continuous curvature and no abrupt changes, and ensures a consistent width. This eliminates parasitic capacitance and inductance at the corner, reduces high-frequency reflection noise at the corner, reduces fluctuations at high frequencies, improves signal integrity, and disperses bending stress.

[0009] In one embodiment, the difference in trace length between two differential signal lines within the same differential line group is no greater than 2 mil.

[0010] In one embodiment, the difference in trace length between differential signal lines in different differential line groups is no greater than 5 mil.

[0011] According to the above scheme, the difference in trace length is strictly controlled, the corresponding error is controlled within the corresponding range, the phase matching within the differential pair is realized synchronously, the global timing synchronization of multiple channels is achieved, and the delay deviation of multi-path parallel transmission is eliminated.

[0012] In one embodiment, the differential line group is arranged in an intermediate layer, and the projection area of ​​the differential line group corresponds to a complete and continuous ground layer.

[0013] In one embodiment, the complete and continuous grounding layer is arranged at both the upper and lower ends of the intermediate layer.

[0014] In one embodiment, the complete continuous grounding layer has a thin copper layer of 0.5 oz.

[0015] According to the above scheme, high-speed signal lines are routed in the middle layer, and a complete and continuous grounding layer is laid in the adjacent layer. The path must not cross the ground. The power supply is split to ensure that the return path is the shortest and continuous, which greatly reduces external crosstalk. The parasitic parameters of the traces can be further reduced by relying on the thin copper layer with a thickness of 0.5oz.

[0016] In one embodiment, each of the two differential signal lines in the same differential line group is connected to a differential signal aperture.

[0017] In one embodiment, a grounding hole is arranged around the outer periphery of the differential signal hole.

[0018] In one embodiment, two differential signal holes connected by two differential signal lines within the same differential line group are arranged on the same anti-pad.

[0019] According to the above scheme, the surrounding grounding holes form local electromagnetic isolation, weaken the crosstalk of pin-end channel coupling, and the anti-pad further reduces parasitic capacitance.

[0020] In one embodiment, differential signal lines arranged in the hard-soft transition region along the direction from the rigid board to the flexible board are configured as gradually expanding traces.

[0021] According to the above scheme, the impedance jump at the interface between soft and hard dielectrics is reduced by gradually widening the trace structure.

[0022] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention employs a smooth, continuous arc transition at the corners of the differential signal lines to ensure impedance continuity, reduce signal reflection at corners, and strictly control the length errors of differential signal lines within and between groups. This achieves dual-level equal-length control, while simultaneously enabling high-precision matching within differential pairs and global timing synchronization across multiple channels. This ensures data misalignment during parallel transmission of multiple GTX signals. Combined with intermediate layer routing and continuous grounding layers on adjacent layers, it further enhances anti-interference capabilities. The entire layer is not split across ground, ensuring a complete and stable return loop. This results in a high-speed signal cabling structure with high anti-interference and low parasitic functionality, combining a rigid-flex board. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall multi-channel GTX wiring layout for a 22-layer rigid-flex PCB. Figure 2 This is a planar diagram showing the routing of differential signal lines on flexible boards, rigid boards, and in the transition zone between flexible and rigid boards. Figure 3 This is a schematic diagram of the arc segment of a differential signal line; Figure 4 This is a schematic diagram of a complete and continuous grounding layer.

[0024] In the picture: 1. Component layout structure; 2. Grounding hole; 3. Differential signal hole; 4. Differential line group; 5. Rigid board differential signal line; 6. Flexible board differential signal line; 7. Rigid-flexible transition area; 8. Arc segment; 9. Complete and continuous ground layer; 10. Anti-soldering pad. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model 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.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings.

[0028] Example 1 This embodiment describes a high-speed signal cabling structure for a rigid-flex PCB with high anti-interference and low parasitic properties. This high-speed signal cabling structure is applied to a rigid-flex PCB and, from the structural perspective, includes: The system comprises a flexible board, a rigid board, and a transition zone 7 between them. The flexible board is connected to the rigid board, and the transition zone 7 is located between the flexible board and the rigid board. Figure 1 As an implementable device layout structure 1, the following is combined with Figures 1-4 The preferred embodiments of this utility model are described below.

[0029] The wiring structure in this embodiment has differential line groups 4. In terms of quantity, there are at least two differential line groups 4, but each differential line group 4 includes two differential signal lines. The two differential signal lines are arranged side by side and are arranged on the flexible board and run to the rigid board through the flexible-rigid transition area 7. The differential signal line on the flexible board is called the flexible board differential signal line 6, and the differential signal line on the rigid board is called the rigid board differential signal line 5. The widths of the flexible board differential signal line 6 and the rigid board differential signal line 5 are not the same. When routing, the differential signal lines arranged on the flexible-rigid transition area 7 along the direction from the rigid board to the flexible board are constructed as gradually widening traces, forming a gradually widening trace structure, reducing the impedance jump at the interface between the flexible and rigid media. Drilling holes is prohibited in the flexible board area and bending area to avoid bending stress pulling through the holes and causing the hole walls to break, effectively releasing bending stress and improving the service life of the flexible-rigid bonding board.

[0030] In this embodiment, the corner segments of the two differential signal lines in the differential line group 4 are constructed as a smooth arc transition with continuous and abrupt curvature of the arc segment 8. The trace width of the differential signal line is kept consistent along the arc segment 8. This structure can eliminate parasitic capacitance and inductance at the corner, reduce high-frequency reflection noise at the corner and reduce fluctuations in high-frequency states, ensure impedance continuity, reduce signal reflection at the corner, improve signal integrity, and disperse bending stress.

[0031] As a dual-level high-precision timing equal-length matching structure, the difference in trace length between two differential signal lines within the same differential line group 4 is no greater than 2 mil, and the difference in trace length between differential signal lines in different differential line groups 4 is no greater than 5 mil. When calculating the difference in trace length between differential signal lines within different differential line groups 4, the average trace length of two differential signal lines within the same differential line group 4 can be used as the calculation basis, or the maximum difference in trace length between differential signal lines within different differential line groups 4 can be used as the calculation basis, i.e., the difference in length between the shortest differential signal line in one differential line group 4 and the longest differential signal line in another differential line group 4. This embodiment achieves phase matching within differential pairs and global timing synchronization across multiple channels by strictly controlling the trace length difference, eliminating delay deviations in multi-channel parallel transmission, and ensuring no data misalignment in multi-channel GTX parallel transmission.

[0032] From the perspective of the differential signal line arrangement, the differential line group 4 in this embodiment is arranged in the middle layer. The projection area of ​​all differential line groups 4 corresponds to the complete and continuous ground layer 9. The path must not cross the ground or power supply segment to ensure that the return path is the shortest and continuous. The complete and continuous ground layer 9 is arranged at the upper and lower ends of the middle layer, which greatly reduces external crosstalk. In conjunction with the 0.5oz thick thin copper layer of the complete and continuous ground layer 9, which faces the middle layer, the parasitic parameters of the trace are reduced. The anti-interference capability of this solution is significantly better than the surface trace solution in the prior art.

[0033] In addition, anti-pads 10 are added around the differential signals to reduce parasitic capacitance. As a specific implementation, each of the two differential signal lines in the same differential line group 4 is connected to a differential signal hole 3. Specifically, in the differential pin output area, grounding holes 2 are arranged around the differential signal hole 3. By arranging the dense grounding holes 2, local electromagnetic isolation is formed, reducing crosstalk between the pin ends. The two differential signal holes 3 connected to the two differential signal lines in the same differential line group 4 are arranged on the same anti-pad 10. The anti-pad 10 further reduces parasitic capacitance. As a specific implementation, the anti-pad 10 is strip-shaped, and the two ends of the anti-pad 10 are outwardly convex semi-circular arcs.

[0034] The above content is only for illustrating the technical concept of this utility model and should not be construed as limiting the scope of protection of this utility model. Any modifications made to the technical solution based on the technical concept proposed in this utility model shall fall within the scope of protection of the claims of this utility model.

Claims

1. A high-speed signal cabling structure with high anti-interference and low parasitic function, comprising a flexible board, wherein the flexible board is connected to a rigid board, and a flexible-rigid transition area (7) is provided between the flexible board and the rigid board, characterized in that, Also includes: At least two sets of differential line groups (4), each set of differential line groups (4) includes two differential signal lines, the differential signal lines are arranged on the flexible board and run to the rigid board through the soft-hard transition area (7); The corner segments of the two differential signal lines in the differential line group (4) are constructed as a smooth arc transition with continuous arc curvature without abrupt changes (8), and the trace width of the differential signal line remains consistent along the arc segment (8).

2. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 1, characterized in that, The difference in trace length between two differential signal lines within the same differential line group (4) shall not exceed 2 mil.

3. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 1 or 2, characterized in that, The difference in trace length between the differential signal lines of different differential line groups (4) shall not exceed 5 mil.

4. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 1, characterized in that, The differential line group (4) is arranged in the intermediate layer, and the projection area of ​​the differential line group (4) corresponds to the complete continuous grounding layer (9).

5. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 4, characterized in that, The upper and lower ends of the intermediate layer are both provided with the complete and continuous grounding layer (9).

6. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 4, characterized in that, The complete continuous grounding layer (9) has a thin copper layer of 0.5 oz.

7. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 1, characterized in that, Each of the two differential signal lines in the same differential line group (4) is connected to a differential signal aperture (3).

8. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 7, characterized in that, The differential signal hole (3) is surrounded by a grounding hole (2).

9. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 7, characterized in that, Two differential signal holes (3) connected by two differential signal lines in the same differential line group (4) are arranged on the same anti-soldering pad (10).

10. The high-speed signal wiring structure of a rigid-flex PCB with high anti-interference and low parasitic function according to claim 1, characterized in that, Along the direction from the rigid board to the flexible board, the differential signal lines arranged in the rigid-flex transition region (7) are constructed as gradually expanding traces.

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