Low-stress flexible printed board structure
By using a multi-layer flexible printed circuit board stack structure and a straddle-type electrical connector design, the problems of stress concentration and high space occupation in the bending design of printed circuit boards in aerospace and automotive electronic equipment are solved, realizing the design of flexible printed circuit board cables with low stress and low cost.
Patent Information
- Application Number
- CN202520170805.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-25
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2035-01-25
AI Technical Summary
In existing technologies for aerospace and automotive electronic equipment, the bending design of printed circuit boards has problems of stress concentration and high space occupancy. Especially in complex interface orientations and under extreme space conditions, conventional designs are difficult to achieve reliable assembly and increase costs.
The design employs a low-stress flexible printed circuit board (PCB) structure. Through a multi-layer flexible PCB stacked structure and straddle-type electrical connectors, combined with a flytail rigid-flex composite board, the length of each flexible PCB layer is designed to be unequal. Surface mount pads are used for welding to achieve natural bending and shaping of the flexible area, avoiding stress concentration and tearing.
This design enables flexible printed circuit board cables with low stress and low space occupancy within a limited space, ensuring assembly reliability, avoiding stress concentration and tearing risks during bending, and reducing costs.
Smart Images
Figure CN223843955U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of flexible cable technology, and in particular relates to a low-stress flexible printed circuit board structure. Background Technology
[0002] With the rapid development of aerospace and automotive electronic equipment, the requirements for internal space structures are becoming increasingly stringent, structural compositions are becoming more complex, and the orientation of interfaces between different sections and modules varies. Signals are becoming increasingly complex, and 90° or even 180° bends are frequent, posing significant challenges to the assembly reliability and bendability of products. Currently, the conventional design scheme is as follows:
[0003] 1. For example Figure 4 As shown, conventional printed circuit boards adopt a rigid-flex composite board form, and both the assembly area and the device assembly area adopt a rigid structure. According to the interface direction, appropriate through-hole or bent-hole printed circuit board connectors are selected to reduce bending at the wire exit.
[0004] 2. The bending radius must be at least 12 times the total flexible thickness during the design process.
[0005] This method causes the flexible board on the inside of the bending direction to arch up during bending. Figure 5 As shown, when space requirements are extremely limited, this solution may fail to assemble in practical applications; furthermore, when the flexible bending length is small, it may be impossible to bend, or forced bending may cause tearing of the flexible area. Additionally, to ensure the bending radius, the flexible area needs to be lengthened, leading to increased costs. Summary of the Invention
[0006] To solve the above-mentioned technical problems, this utility model provides a low-stress flexible printed circuit board structure.
[0007] This utility model is achieved through the following technical solution.
[0008] This utility model provides a low-stress flexible printed circuit board structure, including a connector and a printed circuit board cable. The printed circuit board cable includes a first printed circuit board, a second printed circuit board, and a third printed circuit board. One end of the first printed circuit board is connected to the connector, the other end of the first printed circuit board is connected to one end of the second printed circuit board, and the other end of the second printed circuit board is connected to the third printed circuit board.
[0009] Preferably, the connector is soldered to the first printed circuit board via surface mount pads.
[0010] Preferably, the first printed circuit board is a flexible printed circuit board.
[0011] Preferably, the second printed circuit board is a stacked structure comprising several layers of flexible printed circuit boards.
[0012] Preferably, the length of each flexible printed circuit board in the stacked structure is different.
[0013] Preferably, the third printed circuit board is a rigid printed circuit board.
[0014] The beneficial effects of this utility model are as follows:
[0015] This invention calculates and designs the spatial distance of each bend in the stacked structure of the second printed circuit board by using structural constraints and the direction of the electrical connector interface. This enables the structural design of the printed circuit board cable, reduces the stress generated in the flexible area of the printed circuit board cable when it is bent, and thus achieves a flexible printed circuit board cable design with low stress and low space occupancy.
[0016] This invention, under constraints of spatial structure and bending length, considers both design and assembly aspects. It adopts a flying-tail type rigid-flex composite board design concept, combined with a straddle-type electrical connector. The rigid plate structure at one end of the rigid-flex composite board is eliminated, and it is designed as a multi-layered flexible structure of unequal length with overlapping flexible areas. All positions for welding to the connector pins are designed as surface-mount pads. Utilizing the stacked structure of the flexible printed circuit board, the direction of the flexible area and the length of each layer of the bending area are determined in advance using 3D printing software. All positions for welding to the connector pins are designed as surface-mount pads. During assembly, after welding each layer of the designed flexible board position, the bending area naturally bends and forms a low-stress book-like structure. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the structure of this utility model;
[0018] Figure 2 This is a schematic diagram of the bent state of the printed circuit board cable of this utility model;
[0019] Figure 3 This is a schematic diagram of the printed circuit board cable of this utility model in a flattened state;
[0020] Figure 4 This is a schematic diagram of the flattened state of a printed circuit board in existing technology;
[0021] Figure 5 This is a schematic diagram of the bent state of a printed circuit board in existing technology;
[0022] In the diagram: 1-connector, 2-printed board cable, 21-first printed board, 22-second printed board, 23-third printed board. Detailed Implementation
[0023] The technical solution of this utility model is further described below, but the scope of protection is not limited to what is described.
[0024] Example:
[0025] like Figures 1 to 3 As shown, a low-stress flexible printed circuit board structure includes a connector 1 and a printed circuit board cable 2. The printed circuit board cable 2 includes a first printed circuit board 21, a second printed circuit board 22, and a third printed circuit board 23. One end of the first printed circuit board 21 is connected to the connector 1, the other end of the first printed circuit board 21 is connected to one end of the second printed circuit board 22, and the other end of the second printed circuit board 22 is connected to the third printed circuit board 23. The printed circuit board cable 2 is a two-port rigid-flex composite board.
[0026] The connector 1 is soldered to the first printed circuit board 21 via surface mount pads.
[0027] The first printed circuit board 21 is a flexible printed circuit board, and is fitted with a straddle-type electrical connector 1. The first printed circuit board 21 may have the same stacked structure as the second printed circuit board 22. The first printed circuit board 21 and the second printed circuit board 22 form a flexible region.
[0028] The second printed circuit board 22 is a stacked structure comprising several layers of flexible printed circuit boards.
[0029] The length of each flexible printed circuit board in the stacked structure is different.
[0030] The third printed circuit board 23 is a rigid printed circuit board that can be equipped with various types of components.
[0031] In the flexible printed circuit board stack structure of the second printed circuit board 22, if the second printed circuit board 22 has n layers, the formula for calculating the length of a single flexible printed circuit board is:
[0032]
[0033] In the formula, l is the length of the non-bending area on the second printed circuit board 22; w is the distance between the nth layer second printed circuit board 22 and the innermost second printed circuit board 22; θ is the bending angle of the second printed circuit board 22; R is the bending diameter of the innermost second printed circuit board 22; d is the thickness of the innermost second printed circuit board 22; and L is the length of the nth layer second printed circuit board 22.
[0034] This utility model adopts a rigid pressing structure at one end and a flexible flying tail structure of unequal length at the other end, combined with a straddle-type electrical connector, so that the flexible printed circuit board cable naturally bends towards the shorter flexible layer after assembly. When bending, due to the length difference between the inner and outer layers, the inner layer does not bulge. Therefore, the space occupied is consistent with the overall thickness of the flexible area, achieving the effect of weight reduction and space occupancy reduction. At the same time, it avoids the risk of the flexible area being torn due to the inner layer bulging applying stress to the rigid-flexible joint area during bending.
Claims
1. A low-stress flexible printed circuit board structure, characterized in that: The device includes a connector (1) and a printed circuit board cable (2). The printed circuit board cable (2) includes a first printed circuit board (21), a second printed circuit board (22), and a third printed circuit board (23). One end of the first printed circuit board (21) is connected to the connector (1), the other end of the first printed circuit board (21) is connected to one end of the second printed circuit board (22), and the other end of the second printed circuit board (22) is connected to the third printed circuit board (23).
2. The low-stress flexible printed circuit board structure as described in claim 1, characterized in that: The connector (1) is soldered to the first printed circuit board (21) via surface mount pads.
3. The low-stress flexible printed circuit board structure as described in claim 1, characterized in that: The first printed circuit board (21) is a flexible printed circuit board.
4. The low-stress flexible printed circuit board structure as described in claim 1, characterized in that: The second printed circuit board (22) is a stacked structure comprising several layers of flexible printed circuit boards.
5. The low-stress flexible printed circuit board structure as described in claim 4, characterized in that: The length of each flexible printed circuit board in the stacked structure is different.
6. The low-stress flexible printed circuit board structure as described in claim 1, characterized in that: The third printed circuit board (23) is a rigid printed circuit board.