Circuit board structure for optimizing impedance deviation of differential wiring of HDMI (High Definition Multimedia Interface)

Abstract

The utility model discloses a circuit board structure for optimizing the impedance deviation of the differential wiring of HDMI, which comprises a multilayer circuit board, the multilayer circuit board comprises a plurality of copper foil layers stacked in sequence and HDMI arranged on one copper foil layer, the HDMI is welded on the copper foil layers through patch bonding pads, two adjacent pairs of patch bonding pads are connected through a differential signal wiring, and the impedance deviation of the differential wiring of the HDMI is optimized. The lower copper foil layer corresponding to the patch bonding pad is provided with a hollow area, and GND copper sheets are laid around the differential signal wires on the copper foil layer where the differential signal wires are located. According to the embodiment of the invention, the distance between the patch bonding pad of the differential signal and the reference layer is increased, so that the impedance matching of the differential signal is realized, and the reflection and attenuation of the signal in the transmission process can be effectively reduced; in the wiring layer of the differential signals, the GND copper sheet is used for wrapping the differential wires of the HDMI, so that other signal impurities in the substrate are prevented from interfering the quality of the differential signals of the HDMI, crosstalk is avoided, and the integrity of the differential signals is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit boards, and more specifically to a circuit board structure for optimizing differential wiring impedance deviation of HDMI. Background Art

[0002] Printed circuit boards, or PCBs for short, are an indispensable component of electronic products. As the physical support for electronic components and a bridge for signal transmission, PCBs carry important tasks for the operation and communication of electronic equipment. With the rapid development of science and technology and the continuous innovation of electronic technology, the design and manufacturing technology of PCBs are also changing with each passing day, constantly meeting the increasingly complex needs of electronic products.

[0003] HDMI, as a fully digital video and audio transmission interface, has become a standard configuration for connecting many electronic devices. From set-top boxes, DVD players, to personal computers, TVs, game consoles, and audio equipment, HDMI plays a vital role. It supports a variety of video and audio formats, including high-definition 1080P resolution and high-quality audio formats such as Dolby Digital, and the maximum data transmission speed can reach an astonishing 18Gbps, bringing users an unprecedented audio-visual experience.

[0004] However, as the electronic transmission rate continues to rise, the difficulty of HDMI differential signal design is gradually increasing. In particular, the signal impedance mismatch will have a great impact on the quality of high-speed signals, and then cause various signal integrity problems caused by impedance mismatch.

[0005] In particular, the position of the HDMI device patch pad is critical. The impedance of the HDMI high-speed differential signal line at the patch pad will be low, resulting in impedance mismatch. This impedance mismatch will not only affect the high-speed signal line, causing signal distortion or attenuation, but also pose a potential threat to the performance of the entire electronic system. Utility Model Content

[0006] In order to overcome the problem that the impedance of the existing HDMI high-speed differential signal line is low at the position of the patch pad, thereby causing the impedance mismatch problem, the utility model provides a circuit board structure for optimizing the impedance deviation of the HDMI differential routing.

[0007] The technical solution of the utility model is as follows:

[0008] The utility model according to the above scheme includes a multi-layer circuit board, which includes multiple copper foil layers stacked in sequence and an HDMI arranged on one of the copper foil layers, the HDMI is soldered on the copper foil layer through a patch pad, and two adjacent pairs of patch pads are connected through differential signal traces. The lower copper foil layer corresponding to the patch pad is provided with a hollow area, and the copper foil layer where the differential signal trace is located is paved with GND copper foil around the differential signal trace to optimize the impedance deviation of the HDMI differential signal.

[0009] According to the above solution of the utility model, the size of the hollowed-out area is not less than the size of a pair of patch pads.

[0010] According to the above-mentioned solution of the utility model, the distance between the hollowed-out area and the patch pad in the X-axis direction is 0.15 mm, and the distance between the hollowed-out area and the patch pad in the Y-axis direction is 0.15 mm.

[0011] According to the above-mentioned solution of the utility model, one end of the differential signal wiring is connected to the differential signal hole.

[0012] According to the above-mentioned solution of the utility model, the spacing between the GND copper sheet and the differential signal hole, the spacing between the GND copper sheet and the differential signal trace, and the spacing between the GND copper sheet and the patch pad are equal.

[0013] According to the above-mentioned scheme of the utility model, the spacing between the GND copper skin and the differential signal hole is greater than 0.5mm, the spacing between the GND copper skin and the differential signal routing is greater than 0.5mm, and the spacing between the GND copper skin and the patch pad is greater than 0.5mm.

[0014] According to the utility model of the above scheme, the copper foil layer where the patch pad is located is provided with GND return holes around the patch pad.

[0015] According to the above-mentioned solution of the utility model, the distance between the GND return hole and the patch pad is greater than 1.0 mm.

[0016] According to the utility model of the above solution, the HDMI is provided with a device silk screen, and the device silk screen avoids the differential signal routing.

[0017] According to the utility model of the above solution, the spacing between the device silk screen and the differential signal routing is 0.1 mm.

[0018] The utility model according to the above scheme has the beneficial effect that, by increasing the spacing between the patch pad of the differential signal and the reference layer, the impedance of the differential signal is matched, which can effectively reduce the reflection and attenuation of the signal during transmission, thereby improving the transmission efficiency and quality of the signal; in the wiring layer of the differential signal, the GND copper foil is used to wrap the differential traces of the HDMI to prevent other signal impurities in the substrate from interfering with the differential signal quality of the HDMI, avoid crosstalk, and ensure the integrity of the differential signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the circuit board of the utility model;

[0020] Figure 2 It is a structural schematic diagram of the hollowed-out layer of the circuit board of the utility model.

[0021] In the drawings, the reference numerals are as follows:

[0022] 1. Circuit board; 11. SMD pad; 12. Differential signal routing; 13. Hollow area; 14. GND copper foil; 15. Differential signal hole; 16. GND return hole; 17. Device silk screen. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present utility model are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. Terms such as "setting" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "bottom", etc. are based on the directions or positions shown in the drawings, which are only for the convenience of description and cannot be understood as limitations on the present technical solution.

[0025] It should be noted that the high-speed differential signal line of HDMI will have low impedance at the location of the patch pad 11, resulting in impedance mismatch. This impedance mismatch will not only affect the high-speed signal line, causing signal distortion or attenuation, but also pose a potential threat to the performance of the entire electronic system.

[0026] like Figure 1-Figure 2 As shown, this embodiment provides a circuit board 1 structure for optimizing the impedance deviation of HDMI differential traces, and effectively optimizes the impedance deviation problem of HDMI differential traces by increasing the distance between the patch pad 11 and the reference layer and using the GND copper foil 14 to wrap the differential signal trace 12.

[0027] Specifically, the circuit board 1 structure for optimizing the impedance deviation of the differential trace of HDMI includes a multi-layer circuit board 1, and the multi-layer circuit board 1 includes multiple layers of copper foil layers stacked in sequence and HDMI arranged on a copper foil layer, and the HDMI is soldered on the copper foil layer through a patch pad 11, and two adjacent pairs of patch pads 11 are connected through differential signal traces 12, and the differential signal traces 12 are responsible for transmitting the differential signal of HDMI. The lower copper foil layer corresponding to the patch pad 11 is provided with a hollow area 13, and the hollow area 13 can reduce the interference of the lower copper foil to the differential signal trace 12, so that the signal can be transmitted more purely. And the copper foil layer where the differential signal trace 12 is located is paved with GND copper foil 14 around the differential signal trace 12, and the GND copper foil 14 forms a shielding layer, which can effectively block the interference of impurities of other signals in the substrate to the HDMI differential signal. Even in the design of a high-density circuit board 1, the integrity of the HDMI differential signal can be well guaranteed.

[0028] In this embodiment, the impedance of the differential signal is matched by increasing the distance between the patch pad 11 of the differential signal and the reference layer, which can effectively reduce the reflection and attenuation of the signal during transmission, thereby improving the transmission efficiency and quality of the signal; in the wiring layer of the differential signal, the GND copper foil 14 is used to wrap the differential traces of the HDMI to prevent other signal impurities in the substrate from interfering with the differential signal quality of the HDMI, avoid crosstalk, and ensure the integrity of the differential signal.

[0029] For example, HDMI and its patch pad 11 are on the L1 layer. By hollowing out the copper foil of the layer directly below the patch pad 11 (the L2 layer), the patch pad 11 can be directly referenced to the copper foil of the L3 layer. As the distance between the patch pad 11 and the reference layer increases, the impedance of the patch pad 11 increases, which can improve the situation where the impedance of the differential signal line at the location of the patch pad 11 is low, so that the differential impedance signal of the differential signal line achieves impedance consistency at the location of the patch pad 11, and there will be no impedance mismatch problem, which can solve various signal integrity problems caused by impedance mismatch.

[0030] In one embodiment, the size of the hollowed-out area 13 is not less than the size of a pair of patch pads 11, which can ensure that the differential signal trace 12 will not be interfered by the lower copper foil during transmission, and the differential signal trace 12 can maintain a stable impedance during transmission, reducing signal reflection and attenuation. Preferably, the spacing between the hollowed-out area 13 and the patch pad 11 in the X-axis direction is 0.15mm, which can ensure that the differential signal trace 12 will not be electromagnetically interfered by the lower copper foil in the horizontal direction; the spacing between the hollowed-out area 13 and the patch pad 11 in the Y-axis direction is 0.15mm, which can reduce signal crosstalk in the vertical direction and further improve the transmission quality of the differential signal.

[0031] In one embodiment, one end of the differential signal trace 12 is connected to the differential signal hole 15. The differential signal hole 15 serves as a key interface for signal input and output. The differential signal trace 12 is connected to the differential signal hole 15 to ensure smooth transmission of the signal.

[0032] Preferably, the spacing between the GND copper foil 14 and the differential signal hole 15, the spacing between the GND copper foil 14 and the differential signal trace 12, and the spacing between the GND copper foil 14 and the patch pad 11 are equal, which successfully achieves the optimization of the HDMI differential trace impedance deviation and ensures the integrity of the differential signal. The spacing between the GND copper foil 14 and the differential signal hole 15 is greater than 0.5mm, the spacing between the GND copper foil 14 and the differential signal trace 12 is greater than 0.5mm, and the spacing between the GND copper foil 14 and the patch pad 11 is greater than 0.5mm. The setting of the 0.5mm distance can ensure that the GND copper foil 14 will not interfere with other signal lines or pads while playing a shielding role.

[0033] In one embodiment, the quality of HDMI differential signal coupling is further improved. In the copper foil layer where the patch pad 11 is located, GND return holes 16 are provided around the patch pad 11, and GND return holes 16 are added near both sides of the HDMI patch pad 11, so that the return plane of the HDMI device reaches an optimal state, thereby significantly improving the transmission quality of the differential signal.

[0034] The setting of the GND return hole 16 not only helps to provide a good ground loop, reduce signal reflection and loss, but also effectively absorbs and disperses electromagnetic interference, protecting the differential signal from external noise interference. Adding GND return holes 16 near both sides of the HDMI patch pad 11 further shortens the return path, reduces the impedance of signal transmission, and significantly improves the coupling quality of the differential signal.

[0035] Preferably, the spacing between the GND return hole 16 and the patch pad 11 is greater than 1.0 mm, which not only avoids electromagnetic coupling between the return hole and the pad, but also ensures that the return hole can fully play its role, providing a strong guarantee for the stable transmission of differential signals.

[0036] In one embodiment, HDMI is provided with a device silk screen 17, and the device silk screen 17 avoids the differential signal routing 12. If the avoidance is not done, the device silk screen 17 will be processed, and part of the device silk screen 17 will overlap with the differential routing, and the overlapping part will affect the differential impedance and cause impedance fluctuations. Therefore, the device silk screen 17 needs to avoid the high-speed differential routing.

[0037] Preferably, the distance between the device silk screen 17 and the differential signal trace 12 is 0.1 mm.

[0038] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the claims attached to the utility model.

[0039] The above is an exemplary description of the utility model patent in conjunction with the accompanying drawings. It is obvious that the implementation of the utility model patent is not limited to the above-mentioned method. As long as various improvements are made by adopting the method concept and technical solution of the utility model patent, or the concept and technical solution of the utility model patent are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A circuit board structure for optimizing the impedance deviation of differential traces of HDMI, characterized in that: The invention comprises a multi-layer circuit board, wherein the multi-layer circuit board comprises a plurality of copper foil layers stacked in sequence and an HDMI arranged on one of the copper foil layers, wherein the HDMI is soldered on the copper foil layer via a patch pad, and two adjacent pairs of patch pads are connected via differential signal traces, and a hollow area is provided in the lower copper foil layer corresponding to the patch pad, and a GND copper foil is laid around the copper foil layer where the differential signal trace is located, so as to optimize the impedance deviation of the HDMI differential signal.

2. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 1, characterized in that: The size of the hollowed-out area is not less than the size of a pair of patch pads.

3. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 2, characterized in that: The distance between the hollowed-out area and the patch pad in the X-axis direction is 0.15 mm, and the distance between the hollowed-out area and the patch pad in the Y-axis direction is 0.15 mm.

4. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 1, characterized in that: One end of the differential signal wiring is connected to the differential signal hole.

5. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 4, characterized in that: The spacing between the GND copper sheet and the differential signal hole, the spacing between the GND copper sheet and the differential signal trace, and the spacing between the GND copper sheet and the patch pad are equal.

6. The circuit board structure for optimizing the impedance deviation of differential traces of HDMI according to claim 5, characterized in that: The spacing between the GND copper sheet and the differential signal hole is greater than 0.5 mm, the spacing between the GND copper sheet and the differential signal trace is greater than 0.5 mm, and the spacing between the GND copper sheet and the patch pad is greater than 0.5 mm.

7. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 1, characterized in that: The copper foil layer where the patch pad is located is provided with GND return holes around the patch pad.

8. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 7, characterized in that: The distance between the GND return hole and the patch pad is greater than 1.0 mm.

9. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 1, characterized in that: The HDMI is provided with a device silk screen, and the device silk screen avoids the differential signal routing.

10. The circuit board structure for optimizing the differential trace impedance deviation of HDMI according to claim 9, characterized in that: The spacing between the device silk screen and the differential signal trace is 0.1 mm.

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