PCB structure for optimizing high-frequency resonance of board edge radio frequency connector

Abstract

The utility model relates to a PCB structure for optimizing high-frequency resonance of a board edge radio frequency connector, the board edge of a circuit board is provided with a pair of screw holes, the screw holes are non-metallized holes, and the screw holes pass through a plurality of reference ground planes and are insulated from the reference ground planes; a plurality of ground through holes are formed between the two screw holes; wherein a reference ground plane and a ground via adjacent to the reference ground plane form a backflow path of the radio frequency connector. According to the utility model, the screw hole is designed to be the non-metallized hole, and the outer hole wall of the screw hole is insulated from the reference ground plane, so that a backflow signal cannot be communicated in the multi-layer reference ground plane by means of the screw hole, and a farther backflow path passing through the screw hole is eliminated; according to the invention, a backflow signal of a reference ground plane can only return from an adjacent ground via hole, a closer backflow path is ensured, after a high-frequency signal passes through the closer backflow path, a resonance point is eliminated, the linearity of an insertion loss curve is higher, and the signal transmission quality is effectively improved.

Description

Technical Field

[0001] The utility model relates to the field of circuit boards, in particular to a PCB structure for optimizing the high-frequency resonance of a board-edge radio frequency connector. Background Art

[0002] Printed Circuit Board (PCB) is an important part of the physical support and signal transmission of electronic products, and PCB traces are the most common structure on the circuit board. In some high-frequency test applications, due to structural problems, vertical RF connectors cannot be used, and only board-edge RF connectors can be used. The use of board-edge RF connectors places high demands on PCB design details.

[0003] The board-edge RF connector is installed on the side of the circuit board and is fixed to the circuit board by screws. Therefore, the board edge is provided with corresponding screw holes, and the screw holes penetrate into the multi-layer circuit board. When installing the RF connector, first align the mounting hole on the RF connector with the screw hole, and then tighten the screw to fix it.

[0004] In traditional circuit board design, screw holes are made into metalized holes by default. Since the middle layer of the multi-layer circuit board has a reference ground plane, the side wall of the screw hole is connected to the reference ground plane, that is, a GND network is attached to connect the multi-layer reference ground plane, which is equivalent to a larger ground via. This structure of the circuit board has little effect on the previous low-speed signal transmission, but with the iteration and development of technology, the signal transmission rate is getting higher and higher. If the screw hole is still connected to the multi-layer reference ground plane, the return signal from the RF connector will flow to this larger ground via through the position where it just came in, and then return from the bottom board to the surface board, which is equivalent to adding a very long return path. With the high-frequency signal, obvious high-frequency resonance is generated, resulting in a sharp drop point in the signal insertion loss curve and poor linearity.

[0005] The above problems are worth solving. Utility Model Content

[0006] In order to solve the problem that the signal transmission between the existing board-edge RF connector and the circuit board has a high-frequency resonance point and the signal transmission quality is poor, the utility model provides a PCB structure for optimizing the high-frequency resonance of the board-edge RF connector.

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

[0008] A PCB structure for optimizing high-frequency resonance of a board-edge radio frequency connector, comprising a circuit board with a multi-layer structure, having a surface board, a bottom board and a plurality of middle boards, wherein the middle boards serve as reference ground planes of the surface boards, and a pair of screw holes are provided at the board edge of the circuit board, wherein the screw holes are used to install and fix the radio frequency connector, and the screw holes are characterized in that the screw holes are non-metallized holes, the screw holes pass through a plurality of reference ground planes, and the screw holes are insulated from the reference ground planes;

[0009] A plurality of ground vias penetrating and connecting the reference ground plane are arranged between the two screw holes, wherein one of the reference ground planes and a ground via adjacent to the reference ground plane form a return path of the radio frequency connector.

[0010] The utility model according to the above scheme is characterized in that the screw hole passes through a plurality of intermediate layers from the surface layer plate downward.

[0011] The utility model according to the above scheme is characterized in that the screw holes penetrate from the bottom layer plate upward through a plurality of middle layer plates.

[0012] The utility model according to the above scheme is characterized in that one end of the screw hole is connected to the surface plate, the other end is connected to the bottom plate, and the screw hole passes through all the intermediate plates.

[0013] The utility model according to the above scheme is characterized in that two rows of symmetrical ground via holes are provided between the two screw holes, and the arrangement direction of the two rows of ground via holes is perpendicular to the connection direction of the two screw holes.

[0014] The utility model according to the above solution is characterized in that the radio frequency connector is provided with two connection bases, the connection bases are provided with mounting holes, and the two mounting holes correspond to the two screw holes one by one.

[0015] Furthermore, the mounting hole and the screw hole are connected by screws, and the connecting seat is fixed on the surface plate.

[0016] Furthermore, an electrical conductor is provided in the middle of the RF connector, and the electrical conductor is connected to the transmission line on the surface board.

[0017] The utility model according to the above scheme has the following beneficial effects:

[0018] The utility model designs the screw hole as a non-metallized hole, the outer hole wall of the screw hole is insulated from the reference ground plane, and no ground network is given to the screw hole, so that the return signal cannot communicate in the multi-layer reference ground plane with the help of the screw hole, thereby eliminating the return path that passes through the screw hole and is relatively far away, and the return signal of the reference ground plane can only return from an adjacent ground via hole, ensuring that the return path is relatively close. After the high-frequency signal passes through the relatively close return path, the resonance point is eliminated, thereby achieving a high linearity of the insertion loss curve and effectively improving the signal transmission quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the connection between the radio frequency connector and the circuit board of the utility model;

[0020] Figure 2 It is an enlarged view of the circuit board structure of the utility model;

[0021] Figure 3 It is a partial enlarged view of the existing circuit board structure;

[0022] Figure 4 It is a comparison diagram of insertion loss curves between the prior art and the utility model.

[0023] In the figure,

[0024] 1. RF connector; 11. Mounting hole; 12. Electrical conductor;

[0025] 2. Circuit board; 21. Screw hole; 22. Ground via; 23. Transmission trace; 201. Surface board; 202. Reference ground plane; 203. Bottom board. DETAILED DESCRIPTION

[0026] In order to better understand the purpose, technical solution and technical effect of the utility model, the utility model is further explained in conjunction with the drawings and embodiments below. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, it is stated that the embodiments described below are only used to explain the utility model and are not used to limit the utility model.

[0027] It should be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may also be a central element, and when an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time.

[0028] The indicated orientation or position relationship is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the application is usually placed when used, or the orientation or position relationship commonly understood by technical personnel in this field, or the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0029] The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Several" means two or more, unless otherwise clearly and specifically defined.

[0030] like Figure 1 As shown, the board-edge RF connector 1 is installed on the board edge of the circuit board. The board-edge RF connector 1 includes two connection seats. The connection seats on each side are provided with a mounting hole 11. The two mounting holes 11 correspond to the two screw holes 21 on the board edge of the circuit board. When installing the RF connector 1, first align the mounting hole 11 on the RF connector 1 with the screw hole 21, and then screw on the screws to fix it. An electrical conductor 12 is also provided in the middle of the board-edge RF connector 1. The electrical conductor 12 is connected to the transmission line 23 on the surface board 201 of the circuit board. In this embodiment, one end of the screw hole 21 is connected to the surface board 201 of the circuit board, and the other end is connected to the bottom board 203 of the circuit board, and the screw hole 21 passes through all the middle boards of the circuit board. The screw hole 21 is a through hole. The screw is inserted into the circuit board from the mounting hole 11 of the connection seat above the circuit board and passes through the bottom board 203 of the circuit board. The end of the screw hole 21 is reinforced by a nut.

[0031] like Figure 3 As shown, the return path under the traditional circuit board structure is the second path b in the figure, which returns to the surface board 201 from the larger screw hole 21. This path is far away from the electrical conductor 12 of the RF connector 1 and the return path is also long.

[0032] like Figure 2As shown, in order to solve the problem that the above-mentioned board-edge RF connector 1 has a high-frequency resonance point under a high-frequency transmission signal and the signal transmission quality is poor, the utility model proposes a PCB structure for optimizing the high-frequency resonance of the board-edge RF connector 1, including a circuit board with a multi-layer board structure, having a surface board 201, a bottom board 203 and a plurality of intermediate boards, the intermediate boards serving as a reference ground plane 202 of the surface board 201, a pair of screw holes 21 are provided on the board edge of the circuit board, the screw holes 21 are non-metallized holes, the screw holes 21 pass through a plurality of reference ground planes 202, but no ground network is given to the screw holes 21, so the outer hole wall of the screw hole 21 is insulated from the reference ground plane 202, and the signal of the reference ground plane 202 cannot flow back from the screw hole 21 to the surface board 201. A plurality of ground vias 22 penetrating and connected to the reference ground plane 202 are provided between the two screw holes 21, so the return signal of the reference ground plane 202 can only return from an adjacent ground via 22, ensuring a closer return path. After the high-frequency signal passes through the closer return path, the resonance point is eliminated. The return path is the first path a in the figure, which returns to the surface board 201 from one of the ground vias 22. This path is closer to the conductor 12 of the RF connector 1, and the return path is also shorter.

[0033] The circuit board and RF connector 1 of the utility model structure are put into the simulation software for signal simulation to obtain the first insertion loss curve A, and the circuit board and RF connector 1 of the traditional structure are put into the simulation software for signal simulation to obtain the second insertion loss curve B. By comparison, it can be seen that at frequencies of about 30 MHz and 57 MHz, the second insertion loss curve B of the traditional structure has two sharp drop points, while the insertion loss curve of the utility model has better linearity. It can be seen that the utility model adopts the above structure, which can effectively eliminate high-frequency resonance points and improve the signal transmission quality.

[0034] In this embodiment, one end of the screw hole 21 is connected to the surface board 201, and the other end is connected to the bottom board 203, and the screw hole 21 passes through all the intermediate boards. It should be noted that since the screw hole 21 is a non-metallized hole, it is equivalent to an insulating hole on the circuit board, and the signal cannot flow through the insulating hole.

[0035] In this embodiment, two rows of symmetrical ground vias 22 are arranged between the two screw holes 21, and the arrangement direction of the two rows of ground vias 22 is perpendicular to the connection direction of the two screw holes 21. The connection direction of the first screw hole and the second screw hole is the X direction, and the two rows of ground vias 22 are arranged along the Y direction.

[0036] In other optional embodiments, the screw hole 21 passes through several intermediate layers from the surface plate 201 downwards, and is an upper blind hole. As in the above embodiment, the connection base of the RF connector 1 is fixed on the surface plate 201, and the screw passes through the mounting hole 11 of the connection base from top to bottom, enters from the opening of the screw hole 21 of the surface plate 201, is inserted into the circuit board and tightened to complete the fixation.

[0037] In other optional embodiments, the screw hole 21 passes through several intermediate layers from the bottom plate 203 upwards, and is a lower blind hole. Different from the above embodiment, the connection base of the RF connector 1 is fixed on the bottom plate 203, and the screw passes through the mounting hole 11 of the connection base from bottom to top, enters from the opening of the screw hole 21 of the bottom plate 203, is inserted into the circuit board and tightened to complete the fixation.

[0038] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0039] The above embodiments only express several implementation methods of the utility model, and the descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A PCB structure for optimizing high-frequency resonance of a board-edge RF connector, comprising a circuit board with a multi-layer structure, having a surface board, a bottom board and a plurality of intermediate boards, wherein the intermediate boards serve as reference ground planes for the surface boards, and a pair of screw holes are provided at the board edge of the circuit board, wherein the screw holes are used to install and fix the RF connector, and wherein: The screw hole is a non-metallized hole, the screw hole passes through a plurality of reference ground planes, and the screw hole is insulated from the reference ground planes; A plurality of ground vias penetrating and connecting the reference ground plane are arranged between the two screw holes; one of the reference ground planes and a ground via adjacent to the reference ground plane form a return path of the radio frequency connector.

2. The PCB structure for optimizing high-frequency resonance of the board-edge RF connector according to claim 1, characterized in that: The screw holes extend from the surface plate downward through a plurality of intermediate plates.

3. The PCB structure for optimizing high-frequency resonance of the board-edge RF connector according to claim 1, characterized in that: The screw holes extend from the bottom layer plate upward through a plurality of middle layer plates.

4. The PCB structure for optimizing high-frequency resonance of the board-edge RF connector according to claim 1, characterized in that: One end of the screw hole is connected to the surface plate, and the other end is connected to the bottom plate, and the screw hole passes through all the middle plates.

5. The PCB structure for optimizing high-frequency resonance of the board-edge RF connector according to claim 1, characterized in that: Two rows of symmetrical ground via holes are arranged between the two screw holes, and the arrangement direction of the two rows of ground via holes is perpendicular to the connection direction of the two screw holes.

6. The PCB structure for optimizing high-frequency resonance of the board-edge RF connector according to claim 1, characterized in that: The radio frequency connector is provided with two connection seats, and the connection seats are provided with mounting holes, and the two mounting holes correspond to the two screw holes one by one.

7. The PCB structure for optimizing high frequency resonance of the board edge RF connector according to claim 6, characterized in that: The mounting hole and the screw hole are connected by screws, and the connecting seat is fixed on the surface plate.

8. The PCB structure for optimizing high-frequency resonance of the board-edge RF connector according to claim 6, characterized in that: An electrical conductor is also provided in the middle of the RF connector, and the electrical conductor is connected to the transmission line on the surface board.

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