Flexible circuit board and optimization method thereof

Abstract

The invention discloses a flexible circuit board and an optimization method thereof, and the method comprises the steps: obtaining the size of a to-be-optimized flexible circuit board, and the size of a steel sheet in the flexible circuit board; determining a shortening size according to the size of the circuit board and the size of the steel sheet; and shortening the size of the steel sheet according to the shortened size. After the circuit board size of the to-be-optimized flexible circuit board and the corresponding steel sheet size are obtained, the size, needing to be shortened, of the steel sheet is determined, and then the size of the steel sheet is shortened according to the shortened size, so that the overall size of the steel sheet is reduced, the swelling amount after heating is reduced, temperature distribution of all parts is more uniform, and shrinkage during cooling is more synchronous; and the internal stress is greatly reduced, so that the deformation of the steel sheet is reduced, and the problems of corrugation and deformation are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board design, and in particular to a flexible circuit board and an optimization method thereof. Background Art

[0002] Pitch optimization is a crucial step in circuit design. Pitch refers to the distance between the centers of adjacent conductors. The appropriate pitch size should be selected based on product requirements.

[0003] However, in the existing production process of large-pitch flexible circuit boards, there are problems such as wrinkles, steel sheet deformation, and connector solder joints. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a flexible circuit board and an optimization method thereof, so as to solve the problems of wrinkles and steel sheet deformation in existing flexible circuit boards with large pitch sizes.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for optimizing a flexible circuit board, comprising: Obtaining the circuit board size of the flexible circuit board to be optimized and the size of the steel sheet in the flexible circuit board; Determining the shortening size according to the size of the circuit board and the size of the steel sheet; The steel sheet is shortened in size according to the shortened size.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A flexible circuit board comprises a substrate, and a steel sheet and a gold finger arranged on the substrate; the gold finger is arranged along the edge of one side of the substrate; the size of the steel sheet is obtained by the above-mentioned flexible circuit board optimization method.

[0007] The beneficial effect of the present invention is that after obtaining the circuit board size of the flexible circuit board to be optimized and the corresponding steel sheet size, the size of the steel sheet that needs to be shortened is determined, and then the size of the steel sheet is shortened according to the shortened size, so that the overall volume of the steel sheet is reduced, the expansion after heating is reduced, and the temperature distribution of each part is more uniform, the contraction during cooling is more synchronized, and the internal stress is greatly reduced, thereby reducing the deformation of the steel sheet itself and avoiding the problems of wrinkles and deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a flowchart of the steps of a method for optimizing a flexible circuit board according to an embodiment of the present invention; Figure 2 is a structural schematic diagram of the flexible circuit board to be optimized; Figure 3 is a schematic structural diagram of a flexible circuit board after being optimized by the flexible circuit board optimization method of this embodiment; Figure 4 is a schematic diagram of the layout of a flexible circuit board according to this embodiment; Description of labels: 1. Base material; 2. Steel sheet; 21. Raised portion; 3. Gold finger; 4. Copper layer. DETAILED DESCRIPTION

[0009] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following description is given in conjunction with the embodiments and accompanying drawings.

[0010] In the related art, a steel sheet structure is required during the production of flexible circuit boards with large pitch sizes. The steel sheet structure is relatively hard and mainly serves to support and bear the load. However, during the welding process, the high temperature generated by welding will cause the steel sheet and connector material to expand due to heat, and then contract when cooled, and internal stress will be generated during the "thermal expansion and contraction" process. If the steel sheet is larger in size, its overall thermal expansion will be greater, and the temperature difference between different parts will be more obvious. For example, the temperature difference between the area near the solder joint and the edge area will be different, resulting in uneven expansion / contraction, which in turn easily causes deformation problems such as twisting and warping.

[0011] In response to the above technical problems, the present invention provides a flexible circuit board and an optimization method thereof, as follows: A method for optimizing a flexible circuit board, comprising: Obtaining the circuit board size of the flexible circuit board to be optimized and the size of the steel sheet in the flexible circuit board; Determining the shortening size according to the size of the circuit board and the size of the steel sheet; The steel sheet is shortened in size according to the shortened size.

[0012] From the above description, it can be seen that the beneficial effect of the present invention is: by obtaining the circuit board size of the flexible circuit board to be optimized and the corresponding steel sheet size, the size of the steel sheet that needs to be shortened is determined, and then the size of the steel sheet is shortened according to the shortened size, so that the overall volume of the steel sheet is reduced, the expansion after heating is reduced, and the temperature distribution of each part is more uniform, the contraction during cooling is more synchronized, and the internal stress is greatly reduced, thereby reducing the deformation of the steel sheet itself and avoiding wrinkles and deformation problems.

[0013] Furthermore, determining the shortening size according to the size of the circuit board and the size of the steel sheet includes: Determining a proportional relationship between the size of the flexible circuit board and the size of the steel sheet; The shortened size is obtained according to the proportional relationship.

[0014] From the above description, it can be seen that when determining the shortening size, it is determined based on the proportional relationship between the size of the flexible circuit board and the size of the steel sheet, which can avoid excessive shortening of the steel sheet size, resulting in the steel sheet being unable to play an effective supporting role.

[0015] Furthermore, determining the proportional relationship between the size of the flexible circuit board and the size of the steel sheet includes: The edge to be shortened on the steel sheet is used as the target edge; The single-side size ratio of each target side to the corresponding side on the flexible circuit board is determined.

[0016] From the above description, it can be seen that the size of each target edge on the steel sheet is compared with the size of the corresponding edge on the flexible circuit board to obtain the single-side size ratio corresponding to each target edge, ensuring that the length of each edge is within the appropriate range.

[0017] Furthermore, obtaining the shortened size according to the size ratio includes: Obtaining the shortened size of the target side according to the single-side size ratio; The shortened dimension is subtracted from the dimension of the steel sheet.

[0018] From the above description, it can be seen that the shortened size of the target side is determined by the unilateral size ratio, that is, each target side is shortened according to its corresponding unilateral size ratio, thereby ensuring that each target side is shortened to an appropriate size.

[0019] Furthermore, the shortened size range includes: 8mm-12mm.

[0020] From the above description, it can be seen that limiting the shortening size range to 8mm-12mm can ensure that the steel sheet plays a supporting role while avoiding wrinkles and deformation problems.

[0021] Furthermore, it also includes: A copper layer is provided on the back side of the gold finger of the flexible circuit board.

[0022] From the above description, it can be seen that by providing a copper layer on the back of the gold finger of the flexible circuit board, the gold finger structure is protected while the copper layer coverage area is increased, thereby improving the heat dissipation effect of the flexible circuit board and avoiding the problem of wrinkles and deformation caused by local excessive temperature.

[0023] Furthermore, the step of providing a copper layer on the back side of the gold finger position of the flexible circuit board includes: A copper layer with a thickness of 6 μm-10 μm is provided.

[0024] It can be seen from the above description that by setting the thickness of the copper layer to 6 μm-10 μm, the gold finger structure can be effectively protected and heat dissipated.

[0025] Another embodiment of the present invention provides a flexible circuit board, comprising a substrate, and a steel sheet and a gold finger arranged on the substrate; the gold finger is arranged along the edge of one side of the substrate; the size of the steel sheet is obtained by a flexible circuit board optimization method as described above.

[0026] From the above description, it can be seen that by using a size-optimized steel sheet structure in a flexible circuit board, the overall volume of the steel sheet is reduced, the expansion after heating is reduced, the temperature distribution of each part is more uniform, the contraction during cooling is more synchronized, and the internal stress is greatly reduced, thereby reducing the deformation of the steel sheet itself and avoiding wrinkles and deformation problems.

[0027] Furthermore, a copper layer is provided on the gold finger.

[0028] From the above description, it can be seen that by providing a copper layer on the gold finger, the gold finger structure is protected while the copper layer coverage area is increased, thereby improving the heat dissipation effect of the flexible circuit board and avoiding the problem of wrinkles and deformation caused by local excessive temperature.

[0029] Furthermore, the steel sheet includes a raised portion; the raised portion faces the gold finger.

[0030] As can be seen from the above description, by providing a protrusion on the steel sheet and orienting the protrusion toward the gold finger, the steel sheet effectively supports the entire substrate and the gold finger structure.

[0031] The flexible circuit board and its preparation method provided by the present invention can be applied to application scenarios of flexible circuit boards with large pitch sizes, such as pitch sizes greater than 200mm. Steel sheet support is required during the production process of large pitch flexible circuit boards. The present invention effectively solves problems such as wrinkles, steel sheet deformation, and connector solder joints in the production process of large-pitch flexible circuit boards, improves product yield, and reduces production costs. The following is an explanation through specific embodiments: Example 1 Please refer to Figure 1 , a method for optimizing a flexible circuit board, comprising: S1. Obtain the dimensions of the flexible circuit board to be optimized, as well as the dimensions of the steel sheet within the flexible circuit board. In this embodiment, the flexible circuit board is a strip-shaped structure, with its length significantly greater than its width. Therefore, the length dimension is primarily considered; for example, the flexible circuit board is 200 mm in size and the steel sheet is 70 mm in size. For other flexible circuit board shapes, the dimensions in each direction must be comprehensively considered.

[0032] S2. Determine the shortening size based on the size of the circuit board and the size of the steel sheet; wherein, when the size of the steel sheet is larger, its overall thermal expansion is greater; if the size of the steel sheet is reduced too much, there is a possibility that the steel sheet 2 cannot effectively support the flexible circuit board. Therefore, the size range in which the steel sheet 2 can be shortened needs to be determined according to the overall size of the circuit board, the size of the steel sheet and the graphic design.

[0033] For example, in one optional embodiment, the shortened dimension is determined based on a proportional relationship of dimensions. Specifically, a proportional relationship between the dimensions of the flexible circuit board and the dimensions of the steel sheet 2 is determined; and the shortened dimension is obtained based on the proportional relationship. Based on the dimensions of the flexible circuit board and the steel sheet, the proportional relationship is 20 / 7. If the preset ratio threshold is 4 / 1 and the flexible circuit board is 200 mm, the appropriate steel sheet size is 50 mm, resulting in a shortened dimension of 20 mm (70 mm - 50 mm).

[0034] S3, shortening the size of the steel sheet according to the shortened size. That is, shortening the original size of the steel sheet 2 by another 20 mm, so that the final size of the steel sheet 2 is 50 mm; shortening from the original 70 mm to 50 mm.

[0035] Taking the above-mentioned strip structure as an example, when determining the proportional relationship between the size of the flexible circuit board and the size of the steel sheet 2, the specific data of the shortened size can be based on the position where the support load is required according to the unilateral ratio, specifically: The edge to be shortened on the steel sheet 2 is taken as the target edge; for example, in a strip structure, it mainly includes the dimensions on both sides in the length direction. Figure 2 As shown, the steel sheet 2 is in the shape of a "convex" character; it mainly includes the dimensions on both sides in the length direction; for example, if the dimension on the left side already meets the preset dimension, the right side will be used as the target side. Determine the unilateral dimension ratio of each target side and the corresponding side on the flexible circuit board, that is, determine the dimensions of the right target side and the corresponding side on the flexible circuit board. For example, the starting point of the right target side is used as the starting point of the length, then the length of the right target side is 32mm, and the dimension of the corresponding side on the flexible circuit board is 90mm, then the ratio is 90 / 32. Further, the shortened dimension of the target side is obtained according to the unilateral dimension ratio. Taking the preset ratio threshold of 4 / 1 as an example, the shortened dimension is 9.5mm; the shortened dimension is subtracted from the dimension of the steel sheet 2; that is, the original dimension of the steel sheet 2 is shortened by 9.5mm, and the final dimension of the steel sheet 2 is 22.5mm. In an optional embodiment, a shortening dimension range can also be set, for example, the shortening dimension is: 8mm-12mm. The size of the steel sheet is shortened directly according to the shortening dimension. As Figure 3 FIG. 1 is a schematic diagram of the flexible circuit board after size adjustment.

[0036] In addition to adjusting the size of the steel sheet, this embodiment also includes the following steps: A copper layer 4 is provided on the back of the gold fingers 3 of the flexible circuit board. In one optional embodiment, the copper layer 4 has a thickness of 6 μm to 10 μm. In the actual process, the copper plating process retains the copper layer 4 on the back of the fingers of the original flexible circuit board during circuit fabrication, without adding new manufacturing processes or materials.

[0037] Another embodiment of the present invention provides a flexible circuit board, comprising a substrate 1, and a steel sheet 2 and a gold finger 3 provided on the substrate 1; the gold finger 3 is provided along the edge of one side of the substrate 1; wherein the size of the steel sheet 2 is obtained by the above-mentioned method for optimizing a flexible circuit board. The gold finger 3 is also provided with a copper layer 4. Specifically, after copper is applied to the back of the gold finger 3, the thickness increase at the finger position is the sum of 12 μm of the substrate and 8 μm of the plated copper, i.e., 20 μm. Figure 4 As shown, the steel sheet 2 includes a raised portion 21, which faces the gold finger 3. During actual use of the flexible circuit board, the connector is centered on the steel sheet 2, ensuring smooth connector soldering and minimizing deformation of the steel sheet 2 and connector. This method reduces the wrinkle rejection rate to below 8.4% and the connector cold soldering rate to below 0.01%, significantly improving product yield and reducing production costs, offering excellent economic benefits and practicality.

[0038] In summary, the flexible circuit board and its optimization method provided by the present invention effectively solve the problems of wrinkles, steel sheet deformation and connector cold soldering in the production of large-pitch flexible circuit boards by laying copper on the back of the gold finger and optimizing the steel sheet size.

[0039] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for optimizing a flexible circuit board, characterized in that: include: Obtaining the circuit board size of the flexible circuit board to be optimized and the size of the steel sheet in the flexible circuit board; Determining the shortening size according to the size of the circuit board and the size of the steel sheet; The steel sheet is shortened in size according to the shortened size.

2. The method for optimizing a flexible circuit board according to claim 1, wherein: Determining the shortened size according to the size of the circuit board and the size of the steel sheet includes: Determining a proportional relationship between the size of the flexible circuit board and the size of the steel sheet; The shortened size is obtained according to the proportional relationship.

3. The method for optimizing a flexible circuit board according to claim 2, wherein: Determining the proportional relationship between the size of the flexible circuit board and the size of the steel sheet includes: The edge to be shortened on the steel sheet is used as the target edge; The single-side size ratio of each target side to the corresponding side on the flexible circuit board is determined.

4. The method for optimizing a flexible circuit board according to claim 3, wherein: Obtaining the shortened size according to the size ratio includes: Obtaining the shortened size of the target side according to the single-side size ratio; The shortened dimension is subtracted from the dimension of the steel sheet.

5. The method for optimizing a flexible circuit board according to claim 1, wherein: The shortened size range includes: 8mm-12mm.

6. The method for optimizing a flexible circuit board according to claim 1, wherein: Also includes: A copper layer is provided on the back side of the gold finger of the flexible circuit board.

7. The method for optimizing a flexible circuit board according to claim 6, wherein: The step of providing a copper layer on the back side of the gold finger position of the flexible circuit board comprises: A copper layer with a thickness of 6 μm-10 μm is provided.

8. A flexible circuit board, characterized in that: It includes a substrate, and a steel sheet and a gold finger arranged on the substrate; The gold finger is arranged along the edge of one side of the substrate; The size of the steel sheet is obtained by the optimization method for a flexible circuit board according to any one of claims 1 to 5.

9. The flexible circuit board according to claim 8, characterized in that: A copper layer is provided on the gold finger.

10. The flexible circuit board according to claim 8, characterized in that: The steel sheet includes a raised portion; The protrusion faces the gold finger.

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