Flexible circuit board
By setting up plastic strips in the easily deformed area of the flexible circuit board, the problem of difficulty in restoring flatness after the circuit board is bent is solved, and the effect of the circuit board being easily restored to flatness after the circuit board is bent is achieved.
Patent Information
- Application Number
- CN202410092619.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-12-19
- Filing Date
- 2024-01-23
- Publication Date
- 2025-06-20
AI Technical Summary
It is difficult for existing flexible circuit boards to return to a flat state after being bent and deformed, especially the lower half of the substrate is prone to deform and bent and not easy to recover.
Set a shaping bar in the bending and deformable area of the flexible circuit board. When the deformed circuit board is flat, the shaping bar helps to shape the circuit board back to its original flat state.
By setting up plastic shaping strips, the flexible circuit board can easily return to a flat state after bending, improving the plastic shaping ability of the circuit board.
Smart Images
Figure CN120186864A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a flexible printed circuit board, and particularly to a flexible printed circuit board that can be reshaped to a flat state after being deformed and bent. Background Art
[0002] Please refer to Figure 1 and Figure 2 , the existing conventional flexible printed circuit board 20 has a substrate 21, a plurality of circuits 22 and a solder mask layer 23. A first bonding area 21a, a second bonding area 21b and a chip setting area 21c are defined on the surface of the substrate 21. The first bonding area 21a and the second bonding area 21b are respectively located at both ends of the substrate 21, and the chip setting area 21c is located between the first bonding area 21a and the second bonding area 21b. The plurality of circuits 22 are disposed on the substrate 21, and the pins (not shown in the figure) of each circuit 22 are located in the first bonding area 21a, the second bonding area 21b or the chip setting area 21c. The solder mask layer 23 covers the plurality of circuits 22 but does not cover the pins of the plurality of circuits 22.
[0003] The width of the second bonding area 21b is greater than the width of the first bonding area 21a. Therefore, more circuits can be disposed in the area between the chip setting area 21c and the second bonding area 21b. However, the lower half of the substrate 21 where the second bonding area 21b is located is prone to deformation and bending, and even if the flexible printed circuit board 10 is flat-pressed, the substrate 21 is still not easily restored to its original flat state. Summary of the Invention
[0004] An object of the present invention is to provide a flexible printed circuit board, in which shaping strips are disposed in areas where the flexible printed circuit board is prone to bending and deformation. After the deformed flexible printed circuit board is flat-pressed, the plurality of shaping strips contribute to reshaping the flexible printed circuit board back to its original flat state.
[0005] A flexible printed circuit board of the present invention includes a flexible substrate, a plurality of circuits, a solder mask layer and a plurality of shaping strips. The flexible substrate has a first part and a second part, and the second part is connected to the first part. Along a first direction, a first width of the first part is smaller than a second width of the second part. The plurality of circuits are disposed on the surface of the flexible substrate. The solder mask layer covers the surface and the plurality of circuits. The plurality of shaping strips are arranged along the first direction above the solder mask layer of the second part, and there is a space between adjacent shaping strips, and the space exposes the solder mask layer. Each shaping strip extends along a second direction, and the second direction intersects with the first direction.
[0006] The multiple shaping strips are arranged along the first direction and extend along the second direction. By providing the multiple shaping strips, the upper surface of the second part presents a wavy shape with undulations. Even if the second part is deformed and bent, the flexible circuit board can be easily flattened to reshape the second part back to its original flat state when pressed flat. Description of the Drawings
[0007] Figure 1 : Top view of a conventional flexible circuit board.
[0008] Figure 2 : Along Figure 1 Cross-sectional view taken along A-A.
[0009] Figure 3 : Top view of a flexible substrate according to the first embodiment of the present invention.
[0010] Figure 4 : Top view of a flexible circuit board according to the first embodiment of the present invention.
[0011] Figure 5 : Along Figure 4 Cross-sectional view taken along B-B.
[0012] Figure 6 : Top view of a flexible substrate according to the second embodiment of the present invention.
[0013] Figure 7 : Top view of a flexible substrate according to the third embodiment of the present invention.
[0014] Figure 8 : Top view of a flexible circuit board according to the third embodiment of the present invention.
[0015] Figure 9 : Along Figure 8 Cross-sectional view taken along C-C.
[0016]
Description of Main Element Symbols
[0017] 10: Flexible circuit board 100: Flexible substrate
[0018] 110: First part 120: Second part
[0019] 121: First extension section 122: Second extension section
[0020] 123: Connection section 130: Surface
[0021] 131: First bonding area 132: Second bonding area
[0022] 133: Chip setting area 200: Circuit
[0023] 300: Solder mask layer 400: Shaping strip
[0024] 500: dummy circuit 20: Flexible printed circuit board
[0025] 21: Substrate 21a: First bonding area
[0026] 21b: Second bonding area 21c: Chip setting area
[0027] 22: Circuit 23: Solder mask layer
[0028] L1: First length L2: Second length
[0029] L3: Third length X: First direction
[0030] Y: Second direction W1: First width
[0031] W2: Second width Detailed implementation mode
[0032] Please refer to Figures 3 to 5 , which is the first embodiment of the present invention. The flexible printed circuit board 10 includes a flexible substrate 100 and a plurality of circuits 200. The flexible substrate 100 has a first part 110 and a second part 120. The second part 120 is connected to the first part 110. A first bonding area 131, a second bonding area 132 and a chip setting area 133 are defined on the surface 130 of the flexible substrate 100. The first bonding area 131 is located at the free end of the first part 110. The second bonding area 132 is located at the free end of the second part 120. The chip setting area 133 is located between the first bonding area 131 and the second bonding area 132. The plurality of circuits 200 are disposed on the surface 130.
[0033] In this embodiment, the material of the flexible substrate 100 is polyimide. Each of the circuits 200 includes a nickel-chromium layer and a copper layer. The nickel-chromium layer is located between the flexible substrate 100 and the copper layer. In other embodiments, each of the circuits 200 further includes a tin layer formed on the copper layer. The present invention does not limit the material of the flexible substrate 100, which can be made of other flexible materials. The present invention also does not limit the material of the metal layer of each of the circuits 200, which can be made of other suitable metal materials.
[0034] The pins of each of the lines 200 (not shown in the figure) are located in the first bonding area 131, the second bonding area 132, or the chip placement area 133. The pins located in the first bonding area 131 and the second bonding area 132 are external pins for bonding to external electronic devices, and the pins located in the chip placement area 133 are internal pins for bonding to the chip. The plurality of lines 200 includes a plurality of input lines and a plurality of output lines. The plurality of input lines extend from the first bonding area 131 to the chip placement area 133, and the plurality of output lines extend from the chip placement area 133 to the second bonding area 132. The number of the plurality of output lines is greater than the number of the plurality of input lines.
[0035] Please refer to Figure 3 , along the first direction X, the first width W1 of the first part 110 is less than the second width W2 of the second part 120. Therefore, the wider second part 120 can accommodate a larger number of the plurality of output lines. In one embodiment, the first width W1 is less than 2 / 3 of the second width W2.
[0036] Please refer to Figure 3 , preferably, the second part 120 has a first extension section 121, a second extension section 122, and a connection section 123. Along the first direction X, the connection section 123 is located between the first extension section 121 and the second extension section 122, and both sides of the connection section 123 are connected to the first extension section 121 and the second extension section 122 respectively. Along the second direction Y, the connection section 123 is located on one side of the first part 110, and the connection section 123 is connected to the first part 110. The second direction Y intersects the first direction X. In this embodiment, the second direction Y is perpendicular to the first direction X. The second direction Y is longitudinal, and the first direction X is transverse.
[0037] Please refer to Figure 3 , the first extension section 121 has a first length L1 along the first direction X. The first length L1 is the shortest distance from the side of the first part 110 to the side of the first extension section 121. The first extension section 121 has a second length L2 along the second direction Y. Preferably, the first length L1 is greater than the second length L2. The first length L1 is between 15 - 35 mm (15 mm < L1 < 35 mm), and the second length L2 is between 3 - 15 mm (3 mm < L2 < 15 mm). In this embodiment, the first extension section 121 is trapezoidal, and the second length L2 decreases from the connection section 123 towards the side of the first extension section 121. The first extension section 121 and the second extension section 122 have the same shape and size and are mirror-symmetrical about the connection section 123.
[0038] Please refer to Figure 4 and Figure 5, the flexible circuit board 10 further includes a solder mask layer 300 and a plurality of shaping strips 400. The solder mask layer 300 covers the surface 130 and the plurality of circuits 200, but does not cover the first bonding area 131, the second bonding area 132, and the chip setting area 133. The solder mask layer 300 is used to protect the plurality of circuits 200. The plurality of shaping strips 400 are arranged at intervals along the first direction X on the solder mask layer 300 above the second part 120. The plurality of shaping strips 400 are not connected to each other. Therefore, there is a space S between adjacent shaping strips 400. The space S exposes the solder mask layer 300 below, and each shaping strip 400 extends along the second direction Y. Through the solder mask layer 300 and the plurality of shaping strips 400, the present invention forms a surface with undulations above the second part 120.
[0039] During the semiconductor package testing process, the flexible circuit board 10 may be bent and deformed due to temperature changes. A common situation is that both sides of the wider second part 120 bend downward. When the deformed flexible circuit board 10 is flat-pressed, the plurality of shaping strips 400 help to shape the second part 120, so that the second part 120 and the flexible circuit board 10 as a whole return to the original flat state.
[0040] The present invention does not limit the material of the plurality of shaping strips 400, which can be made of any suitable material. In this embodiment, the material of the plurality of shaping strips 400 is a solder mask material, which is formed on the solder mask layer 300 by screen printing technology. The plurality of shaping strips 400 and the solder mask layer 300 can be made of the same or different solder mask materials.
[0041] Please refer to Figure 6 , which is the second embodiment of the present invention. Different from the first embodiment, the first extension section 121 and the second extension section 122 of the second part 120 have different sizes. The second extension section 122 has a third length L3 along the first direction X. The third length L3 is the shortest distance from the side of the first part 110 to the side of the second extension section 122. The third length L3 is not equal to the first length L1. In the second embodiment, the third length L3 is less than the first length L1. In other embodiments, the third length L3 can be greater than the first length L1.
[0042] Please refer to Figures 7 to 9 , which is the third embodiment of the present invention. The flexible circuit board 10 of the third embodiment further includes a plurality of dummy lines 500. The plurality of dummy lines 500 are arranged on the first extension section 121 and the second extension section 122, and are arranged in an area without the plurality of circuits 200. Along the first direction X, the plurality of dummy lines 500 are located on both sides of the plurality of circuits 200, as Figure 7As shown (omitting the multiple circuits 200, the solder mask layer 300, and the multiple shaping bars 400), each dummy circuit 500 extends along the second direction Y. The multiple dummy circuits 500 and the multiple shaping bars 400 extend along the same direction. In addition to reducing the deformation amount of the second portion 120, when the deformed flexible circuit board 10 is flat-pressed, through the multiple dummy circuits 500 and the multiple shaping bars 400, the second portion 120 can be easily shaped back to its original flat state.
[0043] Please refer to Figure 7 , the first extension segment 121 has a first corner 121a, the second extension segment 122 has a second corner 122a. The first corner 121a and the second corner 122a are not connected to the connection segment 123 and are not located in the second bonding area 132. Preferably, the multiple dummy circuits 500 are disposed at the first corner 121a and the second corner 122a. In this embodiment, the lengths of the multiple dummy circuits 500 located at the first extension segment 121 increase in the direction from the connection segment 123 towards the side of the first extension segment 121, and the lengths of the multiple dummy circuits 500 located at the second extension segment 122 increase in the direction from the connection segment 123 towards the side of the second extension segment 122.
[0044] In the present invention, the multiple shaping bars 400 are disposed above the second portion 121. The multiple shaping bars 400 are arranged at intervals along the first direction X and extend along the second direction Y, making the upper surface of the second portion 120 present a wavy shape with undulations. Even if the two sides of the second portion 120 are bent downward, when the flexible circuit board 10 is flat-pressed, the multiple shaping bars 400 contribute to shaping the second portion 120 back to its original flat state.
[0045] The above description is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, may make some modifications or variations equivalent to the equivalent embodiments by using the above-disclosed technical content. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.
Claims
1. A flexible circuit board, characterized in that: Include: The flexible substrate has a first portion and a second portion, wherein the second portion is connected to the first portion, and along a first direction, a first width of the first portion is smaller than a second width of the second portion; A plurality of circuits are arranged on the surface of the flexible substrate; A solder mask layer covering the surface and the plurality of circuits; as well as A plurality of shaping strips are arranged along the first direction on the solder mask above the second portion, with spaces between adjacent shaping strips to expose the solder mask, and each shaping strip extends along a second direction intersecting the first direction.
2. The flexible printed circuit board according to claim 1, characterized in that: The second portion has a first extension segment, a second extension segment and a connecting segment. The connecting segment is located between the first extension segment and the second extension segment, and the connecting segment is connected to the first portion.
3. The flexible printed circuit board according to claim 2, characterized in that: It also includes a plurality of dummy circuits, which are arranged in the first extension section and the second extension section, and each of the dummy circuits extends along the second direction.
4. The flexible printed circuit board according to claim 3, characterized in that: The first extension section has a first corner plate which is not connected to the connection section, the second extension section has a second corner plate which is not connected to the connection section, and the plurality of dummy circuits are located at the first corner plate and the second corner plate.
5. The flexible printed circuit board according to claim 2, characterized in that: The first extension segment has a first length along the first direction, and the first extension segment has a second length along the second direction, and the first length is greater than the second length.
6. The flexible printed circuit board according to claim 5, characterized in that: The second extension section has a third length along the first direction, and the third length is smaller than the first length.
7. The flexible printed circuit board according to claim 1, characterized in that: The first width is smaller than 2 / 3 of the second width.
8. The flexible printed circuit board according to claim 1, characterized in that: The material of the plurality of shaping strips is solder-resistant material.