Bending-resistant flexible welding circuit board

Abstract

According to the bending-resistant flexible welding circuit board provided by the utility model, the design of the arc-shaped bonding pad is adopted, so that the stress of the bonding pad is dispersed when the bonding pad is pulled under the deformation effect of the flexible substrate, the probability that the edge of the bonding pad is broken is greatly reduced, the stress peak point of the bonding pad can be positioned at an arc tangent point due to the arc-shaped arrangement, and even if the point is damaged, the bending-resistant flexible welding circuit board is not damaged. The rest part can still be connected with the wire, so that the bending resistance of the flexible welding circuit board is remarkably improved, and the integrity and reliability of signal transmission are further guaranteed; meanwhile, the head or the tail of the wire wraps the bonding pad, the contact area of the wire and the bonding pad is increased, the risk of interruption of a signal transmission path is reduced, good communication can be maintained, the head and the tail are arranged in an arc shape, the stress of the wire can be dispersed, and the adaptability of the wire to deformation of the flexible substrate is improved. And the durability and the transmission stability of the flexible welding circuit board are improved.

Description

Technical Field

[0001] The utility model relates to the field of printed circuit boards, and more specifically to a flexible welding circuit board with bending resistance. Background Art

[0002] In the field of electronic circuit boards, it is often necessary to connect two printed circuit boards (PCBA) to supply power and communicate. The connection methods of the two PCBA boards are generally divided into hard connection and soft connection. After connection by the former, the two PCBA boards cannot be displaced relative to each other, while the latter allows flexible rotation, twisting and movement. Soft connection technologies include FPC, FFC, rigid-flex boards and plastic wires. Among them, FPC (Flexible Printed Circuit, the full English name: Flexible Printed Circuit) is widely used in the welding and fixing of PCBA boards because it uses polyimide or polyester film as the substrate and has the characteristics of high reliability, flexibility, high wiring density, light weight, thin thickness and good bending property.

[0003] However, the existing flexible welding circuit boards usually adopt a rectangular pad design, and the wire is of the same width as the pad and is directly connected to the pad. When the flexible welding circuit board undergoes long-term or frequent bending, the neat edges of the rectangular pads are easily pulled until completely broken, resulting in low bending resistance of the flexible welding circuit board and affecting the integrity and reliability of signal transmission. Summary of the Utility Model

[0004] The purpose of the utility model is to overcome the defects of the prior art and provide a flexible welding circuit board with bending resistance to solve the technical problem of low bending resistance of traditional flexible welding circuit boards.

[0005] To achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A flexible welding circuit board with bending resistance, which comprises: a flexible substrate, the flexible substrate is provided with a welding surface, and at least one conductive unit is arranged on the welding surface; the conductive unit comprises a wire and two pads, and the two pads are connected by the wire; the wire comprises a head, a tail and a connecting part, the head and the tail respectively surround and connect the two pads, and two ends of the connecting part are connected to the head and the tail; both ends of the head and the tail along the wire transmission direction are arc-shaped, and both ends of the pad along the wire transmission direction are arc-shaped.

[0007] Wherein, both ends of the pad form an arc-shaped contour protruding outward from the center of the pad.

[0008] Wherein, both ends of the head form an arc-shaped contour protruding outward from the head, and both ends of the tail form an arc-shaped contour protruding outward from the tail.

[0009] Wherein, the pad, the head and the tail are oblong.

[0010] Wherein, both ends of the connecting portion extend to the edges of the two pads and are connected to the two pads.

[0011] Wherein, the line width of the connecting portion is smaller than the line width of the head and smaller than the line width of the tail.

[0012] Wherein, the number of the welding surfaces is two, and the two welding surfaces are respectively arranged on two parallel surfaces of the flexible substrate; the number of the conductive units on the two welding surfaces is the same and they are connected one by one.

[0013] Wherein, the pad is provided with a first via hole which penetrates through the flexible substrate, and the first via hole communicates with two conductive units which are respectively located on the two welding surfaces and are correspondingly arranged.

[0014] Wherein, the pads of the two connected conductive units are arranged opposite to each other; one ends of the heads of the two connected conductive units which are close to the connecting portion are arranged in a staggered manner.

[0015] Wherein, the connecting portion is provided with a second via hole which penetrates through the flexible substrate, and the second via hole communicates with two conductive units which are respectively located on the two welding surfaces and are correspondingly arranged.

[0016] The beneficial effects of the present utility model compared with the prior art are as follows: The present utility model adopts the design of an arc-shaped pad, so that when the pad is pulled under the action of the deformation of the flexible substrate, the stress is dispersed, greatly reducing the probability of the edge fracture of the pad. Moreover, the arc-shaped setting can make the stress peak point of the pad located at the tangent point of the arc. Even if this point is damaged, the rest can still maintain the connection with the wire, significantly improving the bending resistance of the flexible printed circuit board, and further ensuring the integrity and reliability of signal transmission. At the same time, by wrapping the head or tail of the wire around the pad, the contact area between the wire and the pad is increased, reducing the risk of signal transmission path interruption, and being able to maintain good communication. The head and the tail are arc-shaped, which can also disperse the stress of the wire, improve the adaptability of the wire to the deformation of the flexible substrate, and enhance the durability and transmission stability of the flexible printed circuit board.

[0017] The above description is only an overview of the technical solution of the present utility model. In order to be able to understand the technical means of the present utility model more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present utility model more obvious and understandable, the following preferred embodiments are specifically described in detail as follows. Description of the Drawings

[0018] Figure 1Schematic diagram of a welding surface of a bend-resistant flexible printed circuit board provided by the present utility model;

[0019] Figure 2 Schematic diagram of another welding surface of a bend-resistant flexible printed circuit board provided by the present utility model.

[0020] Reference numerals:

[0021] 1. Flexible substrate; 2. Conductive unit; 21. Pad; 22. Conductive trace; 221. Head; 222. Tail; 223. Connection part; 23. First via hole; 24. Second via hole. Detailed implementation manners

[0022] In order to make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific implementation manners. The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0023] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0024] It should also be understood that the terms used in this specification of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. As used in this specification of the present utility model and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0025] It should be further understood that the term " / and / " used in this specification of the present utility model and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] See Figure 1-2As shown in the figure, this embodiment discloses a bend-resistant flexible printed circuit board, which includes: a flexible substrate 1 provided with a welding surface, and at least one conductive unit 2 is arranged on the welding surface; the conductive unit 2 includes a wire 22 and two pads 21, and the two pads 21 are connected by the wire 22; the wire 22 includes a head 221, a tail 222 and a connecting portion 223, the head 221 and the tail 222 respectively surround and connect the two pads 21, and both ends of the connecting portion 223 are connected to the head 221 and the tail 222; both ends of the head 221 and the tail 222 along the transmission direction of the wire 22 are arc-shaped, and both ends of the pad 21 along the transmission direction of the wire 22 are arc-shaped.

[0027] The pad 21 of this embodiment provides a welding area. The head 221 and the tail 222 of the wire 22 wrap the pad 21 along the edge of the pad 21. In actual application, the printed circuit board PCBA is welded to the conductive unit 2 through solder to realize the welding and fixation of the flexible printed circuit board and the printed circuit board PCBA; the pad 21 is firmly connected to the head 221 or the tail 222 through solder so that electrical signals can be transmitted between the pad 21 and the wire 22; the transmission direction of the wire 22 in this embodiment is from the head 221 through the connecting portion 223 to the tail 222, and / or from the tail 222 through the connecting portion 223 to the head 221, and the wire 22 realizes bidirectional or unidirectional signal transmission.

[0028] Both ends of the pad 21 in this embodiment are arc-shaped, so that when the pad 21 is pulled under the deformation of the flexible substrate 1, the stress is dispersed, greatly reducing the probability of the edge of the pad 21 breaking. Moreover, the arc-shaped setting can make the stress peak point of the pad 21 located at the tangent point of the arc. Even if this point is damaged, the rest can still maintain the connection with the wire 22, significantly improving the bend resistance of the flexible printed circuit board, and thus ensuring the integrity and reliability of signal transmission; at the same time, by wrapping the pad 21 with the head 221 or the tail 222 of the wire 22, the contact area between the wire 22 and the pad 21 is increased, reducing the risk of signal transmission path interruption, and being able to maintain good communication. The head 221 and the tail 222 are arc-shaped, which can also disperse the stress of the wire 22, improve the adaptability of the wire 22 to the deformation of the flexible substrate 1, and enhance the durability and transmission stability of the flexible printed circuit board. The bend-resistant flexible printed circuit board of this embodiment has good bend resistance and can withstand more than 300 bending tests, achieving a more durable and reliable quality advantage compared with the flexible printed circuit boards on the market now.

[0029] The bend-resistant flexible printed circuit board of this embodiment is suitable for flexible connection of multiple printed circuit boards PCBA. Because of its good bend resistance and flexible characteristics, and small occupied space, it is especially suitable for the connection of multiple printed circuit boards with few functions and no need for plugging and unplugging on drones.

[0030] In this embodiment, the flexible substrate 1 is made of polyimide or polyester film material. It can be understood that in other embodiments, according to actual requirements, polyvinyl chloride or other flexible substrate 1 materials can be used to replace the polyimide or polyester film material.

[0031] Among them, both ends of the pad 21 form an arc-shaped contour protruding outward from the center of the pad 21. Compared with the recessed arc-shaped setting, the convex arc-shaped setting has no sharp tip and the contour is smoother. When the flexible substrate 1 is bent and the pad 21 is subjected to tensile force, the stress will gradually disperse along the arc-shaped contour, reducing the local stress peak and lowering the risk of overall fracture or damage at the edge of the pad 21 caused by stress concentration; the convex arc-shaped contour also has the function of guiding signal transmission. The width at both ends of the pad 21 is smaller than the width at the center of the pad 21, enabling the electrical signal to move from the center of the pad 21 to the convex arc-shaped contour, which improves the signal transmission performance and efficiency to a certain extent.

[0032] Among them, both ends of the head 221 form an arc-shaped contour protruding outward from the head 221, and both ends of the tail 222 form an arc-shaped contour protruding outward from the tail 222. Compared with the recessed arc-shaped setting, the convex arc-shaped setting has no sharp tip and the contour is smoother. When the flexible substrate 1 is bent and the wire 22 follows the bending of the flexible substrate 1, the stress will gradually disperse along the arc-shaped contour, reducing the local stress peak and lowering the risk of connection interruption or damage between the wire 22 and the pad 21 caused by stress concentration.

[0033] In this embodiment, the pad 21, the head 221 and the tail 222 are arranged in an oblong shape. The two ends of the oblong are symmetrical semi-circles, and the middle is a rectangle connecting the two semi-circles, which has good stability and is not easily broken by external forces. It can be understood that in other embodiments, a double-different-diameter circular connection shape (such as a pear shape, an asymmetric ellipse), an ellipse, a circle, a polygon with rounded corners and at least four sides or other shapes with convex arc-shaped settings at both ends are used to replace the oblong shape.

[0034] Among them, both ends of the connecting portion 223 extend to the edges of the two pads 21 and are connected to the two pads 21. The connecting portion 223 is both connected to the head 221 and the tail 222 and directly contacts the edge of the pad 21, which helps to improve the signal transmission efficiency; the head 221 and the tail 222 provide a larger welding space. In the case where the connecting portion 223 is directly connected to the pad 21, the head 221 and the tail 222 of the wire 22 can enhance the heat dissipation capacity of the pad 21 and the welding point. The heat generated by welding or the heat generated by current transmission is dispersed to the flexible substrate 1 through the head 221 or the tail 222, ensuring the safety and reliability of the flexible printed circuit board.

[0035] Among them, the line width of the connecting part 223 is smaller than that of the head part 221 and smaller than that of the tail part 222. The wire 22 on the flexible printed circuit board is made of aluminum foil. When the wire 22 is too wide, the proportion of copper foil increases, which easily leads to a decrease in the overall flexibility and bendability of the flexible printed circuit board. Therefore, the connecting part 223 has a different width from the head part 221 or the tail part 222, ensuring the flexibility of the flexible substrate 1, and thus facilitating the improvement of the bending resistance of the flexible printed circuit board; and the connecting part 223 has a different width from the head part 221 or the tail part 222, reducing the risk of the wire 22 breaking neatly and improving the ability of the wire 22 to adapt to bending.

[0036] Among them, the conductive units 2 are distributed along the length direction of the flexible substrate 1; the number of the conductive units 2 is several, and the several conductive units 2 are arranged in parallel and linearly distributed on the welding surface. That is, the head part 221 and the tail part 222 are respectively located at both ends of the welding surface, and one end of each head part 221 away from the connecting part 223 is flush, and one end of each tail part 222 away from the connecting part 223 is flush. In this embodiment, the number of the conductive units 2 on the welding surface is four. The four conductive units 2 can make the space utilization rate of the flexible substrate 1 high, and at the same time avoid too small spacing between the conductive units 2, ensuring the safety and reliability of the flexible printed circuit board. It can be understood that in other embodiments, the number of the conductive units 2 can be adjusted according to actual needs.

[0037] Among them, the number of welding surfaces is two, and the two welding surfaces are respectively arranged on two parallel surfaces of the flexible substrate 1; the number of the conductive units 2 on the two welding surfaces is the same and they are connected one by one. The two welding surfaces help to realize double-sided welding of the flexible printed circuit board, improving the flexibility and convenience of welding, and thus improving the practicality and user experience of the flexible printed circuit board; the conductive units 2 on the two welding surfaces are connected one by one. When the conductive units 2 on one surface are completely broken or the transmission is interrupted, the same signal on the other welding surface can be used as a backup for transmission, ensuring the continuity and integrity of signal transmission and improving the reliability of the flexible printed circuit board; the connection of the two welding surfaces helps to evenly distribute and dissipate heat, improving the heat dissipation efficiency; the conductive units 2 are distributed on both sides of the flexible substrate 1, improving the balance of the flexible substrate 1 and ensuring the stability of the overall structure.

[0038] Among them, the pad 21 is provided with a first via 23, and the first via 23 penetrates through the flexible substrate 1. The first via 23 communicates with two conductive units 2 respectively located on the two welding surfaces and corresponding to each other. The first via 23 provides a plugging space for the pins of external devices, and at the same time provides a flow path for electrical signals between the flexible substrates 1, facilitating the conduction of the two conductive units 2 located on the two welding surfaces, ensuring the integrity and reliability of signal transmission, and improving the bending resistance performance of the flexible printed circuit board.

[0039] Among them, the pads 21 of two adjacent conductive units 2 are arranged opposite to each other; one ends of the heads 221 of two adjacent conductive units 2 close to the connecting portion 223 are arranged in a staggered manner. One ends of two corresponding heads 221 away from the connecting portion 223 are not flush, and one ends of two corresponding tails 222 away from the connecting portion 223 are not flush, ensuring that the easily broken positions of the wires 22 are staggered when the flexible substrate 1 is repeatedly or continuously bent, and improving the fault tolerance rate of the flexible printed circuit board.

[0040] Among them, the connecting portion 223 is provided with a second via 24, the second via 24 penetrates through the flexible substrate 1, and the second via 24 communicates with two conductive units 2 respectively located on two welding surfaces and arranged correspondingly. The second via 24 provides a flow path for electrical signals between the flexible substrates 1, facilitating the conduction of two conductive units 2 located on two welding surfaces. Even if any end of the wire 22 is broken, the electrical signal can still be transmitted from the other wire 22 through the second via, ensuring the integrity and reliability of signal transmission and improving the bending resistance performance of the flexible printed circuit board.

[0041] Among them, the number of the first vias 23 is two, and the number of the second vias 24 is one or two; the first vias 23 and the second vias 24 are filled with conductive materials. The conductive materials are used to ensure the stable transmission of electrical signals between two welding surfaces.

[0042] A bending-resistant flexible printed circuit board of this embodiment adopts the design of arc-shaped pads, enabling the stress to be dispersed when the pads are pulled under the deformation of the flexible substrate, greatly reducing the probability of the edges of the pads breaking. Moreover, the arc-shaped setting can make the stress peak points of the pads located at the tangent points of the arcs. Even if this point is damaged, the rest can still maintain the connection with the wires, significantly improving the bending resistance performance of the flexible printed circuit board, and further ensuring the integrity and reliability of signal transmission. At the same time, by wrapping the pads with the heads or tails of the wires, the contact area between the wires and the pads is increased, reducing the risk of signal transmission path interruption, being able to maintain good communication. The heads and tails are arranged in an arc shape, which can also disperse the stress of the wires, improving the adaptability of the wires to the deformation of the flexible substrate and enhancing the durability and transmission stability of the flexible printed circuit board.

[0043] The above only uses embodiments to further illustrate the technical content of the present invention to make it easier for readers to understand, but it does not mean that the implementation modes of the present invention are limited to this. Any technical extension or re-creation made according to the present invention is protected by the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. A bending-resistant flexible soldered circuit board, comprising a flexible substrate, characterized in that: The flexible substrate is provided with a welding surface, and at least one conductive unit is provided on the welding surface; the conductive unit includes a wire and two pads, and the two pads are connected by the wire; the wire includes a head, a tail and a connecting part, and the head and the tail respectively surround and connect the two pads, and the two ends of the connecting part are connected to the head and the tail; the two ends of the head and the tail along the transmission direction of the wire are both arranged in an arc shape, and the two ends of the pad along the transmission direction of the wire are arranged in an arc shape.

2. The bending-resistant flexible soldered circuit board according to claim 1, characterized in that: The two ends of the pad form an arc-shaped profile protruding outward from the center of the pad.

3. The bending-resistant flexible soldered circuit board according to claim 2, characterized in that: The two ends of the head portion form an arc-shaped contour protruding outward from the head portion, and the two ends of the tail portion form an arc-shaped contour protruding outward from the tail portion.

4. The bending-resistant flexible soldered circuit board according to claim 3, characterized in that: The pad, the head and the tail are arranged in an oblong shape.

5. The bending-resistant flexible soldered circuit board according to claim 1, characterized in that: Two ends of the connecting portion extend to the edges of the two pads and are connected to the two pads.

6. The bending-resistant flexible soldered circuit board according to claim 1, characterized in that: The line width of the connecting portion is smaller than the line width of the head portion, and smaller than the line width of the tail portion.

7. The bending-resistant flexible soldered circuit board according to any one of claims 1 to 6, characterized in that: The number of the welding surfaces is two, and the two welding surfaces are respectively arranged on two mutually parallel surfaces of the flexible substrate; the number of the conductive units on the two welding surfaces is the same and they are connected one by one.

8. The bending-resistant flexible soldered circuit board according to claim 7, characterized in that: The pad is provided with a first via hole, the first via hole is arranged through the flexible substrate, and the first via hole communicates with two conductive units which are respectively located on the two welding surfaces and are arranged correspondingly.

9. The bending-resistant flexible soldered circuit board according to claim 8, characterized in that: The pads of the two connected conductive units are arranged opposite to each other; and the heads of the two connected conductive units are arranged in a staggered manner near one end of the connecting portion.

10. The bending-resistant flexible soldered circuit board according to claim 7, characterized in that: The connecting portion is provided with a second via hole, the second via hole is arranged through the flexible substrate, and the second via hole communicates with two conductive units which are respectively located on the two welding surfaces and are arranged correspondingly.

Images