FPC structure

Abstract

The utility model relates to the technical field of flexible circuit boards, in particular to an FPC structure. The FPC structure comprises a flexible insulating substrate, a circuit layer and a covering film which are sequentially arranged in a stacked mode in the first direction. The circuit layer comprises a golden finger, the golden finger comprises a plurality of conductive contact pieces, and the plurality of conductive contact pieces are arranged at intervals along a second direction; the cover film comprises a main body part and a convex part which are connected with each other, the main body part is positioned on one side, deviating from the golden finger, of the convex part in a direction perpendicular to the second direction, and the convex part covers part of the conductive contact piece. According to the FPC structure, part of the conductive contact pieces in the golden fingers are covered by the protruding parts, and the other part of the conductive contact pieces are not covered, so that when the FPC structure is bent, the pulling force of the covering film on the golden fingers can be reduced, the limitation of the covering film on the golden fingers is reduced, and the golden fingers are easy to bend and not easy to crack.

Description

Technical Field

[0001] The present application relates to the technical field of flexible circuit boards, and in particular to an FPC structure. Background Art

[0002] FPC (Flexible Printed Circuit) has excellent characteristics such as light weight, thin thickness, free bending and folding, light weight, small size, and good heat dissipation. Therefore, it has been widely used in electronic products and medical equipment.

[0003] In the related art, a flexible circuit board includes a flexible insulating substrate, a circuit layer and a covering film, wherein the circuit layer is arranged on the flexible insulating substrate, and the covering film covers part of the circuit layer. The circuit layer is provided with a gold finger protruding from the covering film and used for electrical connection. When the flexible circuit board is bent by force, both the covering film and the gold finger will bend, but since the gold finger includes a plurality of conductive contacts distributed at intervals, the covering film extends in the distribution direction of the conductive contacts, and the covering film covers part of the surface of the conductive contacts; therefore, when the gold finger is bent, the covering film will restrict the bending of the gold finger, causing the gold finger to break and malfunction. Utility Model Content

[0004] The purpose of the embodiments of the present application is to provide an FPC structure in which the gold fingers are not easily broken when bent.

[0005] To achieve the above-mentioned purpose, the technical solution adopted in the embodiment of the present application is: an FPC structure, including a flexible insulating substrate, a circuit layer and a covering film stacked in sequence along a first direction.

[0006] The circuit layer includes a gold finger, and the gold finger includes a plurality of conductive contacts, and the plurality of conductive contacts are spaced apart along a second direction; the covering film includes a main body and a protruding portion connected to each other, and in a direction perpendicular to the second direction, the main body is located on a side of the protruding portion away from the gold finger, and the protruding portion covers a portion of the conductive contact.

[0007] The beneficial effect of the FPC structure provided by the present application is that part of the conductive contacts in the gold finger are covered by the protrusion, while the other part of the conductive contacts are not covered. Therefore, when the FPC structure is bent, the pulling force of the covering film on the gold finger can be reduced, thereby alleviating the restriction of the covering film on the gold finger, thereby making the gold finger easy to bend and not easy to crack.

[0008] In some embodiments, the outer contour of the end of the protrusion away from the main body is a first arc surface that protrudes in a direction away from the main body.

[0009] In some embodiments, the radius of the first curved surface is 0.2 mm-0.5 mm.

[0010] In some embodiments, the angle between a straight line parallel to the second direction and a tangent line of the first arc surface is 45 degrees to 60 degrees.

[0011] In some embodiments, a plurality of the protrusions are provided, and the protrusions are arranged at intervals along the second direction.

[0012] In some embodiments, the distance between two adjacent protrusions is 1.0 mm-1.5 mm.

[0013] In some embodiments, a recessed portion is defined between two adjacent protrusions, and a distance between an end of the recessed portion away from the gold finger and the gold finger is 0.2 mm-0.3 mm.

[0014] In some embodiments, the outer contour of the end of the recessed portion close to the gold finger is a second arc surface that protrudes in a direction away from the gold finger.

[0015] In some embodiments, the radius of the second curved surface is 0.2 mm-0.5 mm.

[0016] In some embodiments, the angle between a straight line parallel to the second direction and a tangent line of the second arc surface is 45 degrees to 60 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 is a structural schematic diagram of an FPC structure in one of the embodiments of the present application;

[0019] Figure 2 It is a structural diagram of the FPC structure in another embodiment of the present application.

[0020] Reference numerals:

[0021] 1. Flexible insulating substrate; 2. Cover film; 21. Protrusion; 22. Recess; 23. Main body; 3. Gold finger; 31. First conductive contact; 32. Second conductive contact. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] References to "one embodiment", "some embodiments" or "embodiments" described in the specification of the present application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Thus, the statements "in one embodiment", "in some embodiments of the present application", "in some other embodiments", "in some other embodiments", etc. that appear at different places in the specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. In addition, in one or more embodiments, specific features, structures or characteristics can be combined in any suitable manner.

[0026] FPC (Flexible Printed Circuit) has excellent characteristics such as light weight, thin thickness, free bending and folding, light weight, small size, and good heat dissipation. Therefore, it has been widely used in electronic products and medical equipment.

[0027] In the related art, a flexible circuit board includes a flexible insulating substrate, a circuit layer and a covering film, wherein the circuit layer is arranged on the flexible insulating substrate, and the covering film covers part of the circuit layer. The circuit layer is provided with a gold finger protruding from the covering film and used for electrical connection. When the flexible circuit board is bent by force, both the covering film and the gold finger will bend, but since the gold finger includes a plurality of conductive contacts distributed at intervals, the covering film extends in the distribution direction of the conductive contacts, and the covering film covers part of the surface of the conductive contacts; therefore, when the gold finger is bent, the covering film will restrict the bending of the gold finger, causing the gold finger to break and malfunction.

[0028] In view of the above problems, an embodiment of the present application provides an FPC structure, in which the gold fingers are not easily broken when bent.

[0029] In order to illustrate the technical solution of the present application, a description is given below with reference to specific drawings and embodiments.

[0030] Please refer to Figure 1 and Figure 2 An embodiment of the present application provides an FPC structure, comprising a flexible insulating substrate 1, a circuit layer and a cover film 2 which are sequentially stacked along a first direction.

[0031] The circuit layer includes a gold finger 3, which includes a plurality of conductive contacts, and the plurality of conductive contacts are spaced apart along the second direction; the covering film 2 includes a main body 23 and a raised portion 21 connected to each other, and in a direction perpendicular to the second direction, the main body 23 is located on a side of the raised portion 21 away from the gold finger 3, and the raised portion 21 covers part of the conductive contact.

[0032] In the FPC structure provided in the present application, part of the conductive contacts in the gold finger 3 are covered by the protrusion 21, and the other part of the conductive contacts are not covered. Therefore, when the FPC structure is bent, the pulling force of the covering film 2 on the gold finger 3 can be reduced to alleviate the restriction of the covering film 2 on the gold finger 3, thereby making the gold finger 3 easy to bend and not easy to crack.

[0033] Please refer to Figure 1 and Figure 2 In some embodiments, the second direction is the X direction shown in the figure, the distribution direction of the main body 23 and the protrusion 21 is the Y direction shown in the figure, and the first direction is a direction perpendicular to the X direction and the Y direction respectively.

[0034] It should be noted that the circuit layer includes a circuit part and a gold finger 3, the circuit part is electrically connected to the gold finger 3, and the circuit part is covered between the cover film 2 and the flexible insulating substrate 1. The gold finger 3 includes a plurality of first conductive contacts 31 and a plurality of second conductive contacts 32, a portion of the first conductive contacts 31 is covered between the cover film 2 and the flexible insulating substrate 1, and another portion of the first conductive contacts 31 protrudes from the cover film 2 in the Y direction; the second conductive contacts 32 all protrude from the cover film 2. The first conductive contacts 31 and the second conductive contacts 32 protruding from the cover film 2 are used to be electrically connected to other devices (computer host, touch screen, etc.).

[0035] It should be noted that when binding the FPC to a device with a gold finger (such as a thin film touch sensor, touch screen glass, etc.), ACF (Anisotropic Conductive Film) is attached to the surface of the gold finger 3 on the FPC away from the flexible insulating substrate 1, and then the gold finger 3 on the FPC is placed opposite to the gold finger on the device and pressed together, and the anisotropic conductive adhesive is cured to form an anisotropic conductive adhesive film, so that the FPC is bound to the device. During pressing, the anisotropic conductive adhesive will flow due to squeezing.

[0036] In the FPC structure of the related art, all the conductive contacts are partially covered between the cover film 2 and the flexible insulating substrate 1. In the direction in which the conductive contacts are away from the flexible insulating substrate 1, the cover film 2 protrudes from the conductive contacts, so that the contour of the end of the cover film 2 close to the gold finger 3 cooperates with the gold finger 3 to form a step. When there is a lot of anisotropic conductive adhesive, the excess anisotropic conductive adhesive will flow to the edge of the cover film 2 and accumulate on the edge of the cover film 2, thereby causing the conductive particles in the anisotropic conductive adhesive to accumulate on the edge of the cover film 2. This makes it easy for the wire part in the FPC structure to contact the conductive particles accumulated on the edge of the cover film 2, resulting in a short circuit in the circuit of the FPC structure, thereby affecting the normal operation of the FPC structure.

[0037] In the FPC structure of the embodiment of the present application, the second conductive contact piece 32 is not covered by the covering film 2, so that an empty groove can be formed between the second conductive contact piece 32, the covering film 2 and the flexible insulating substrate 1. When the FPC is bound to a device with a gold finger, excess anisotropic conductive adhesive can flow into the above-mentioned groove to prevent the anisotropic conductive adhesive from accumulating, thereby preventing a short circuit in the circuit in the FPC structure.

[0038] Please refer to Figure 1 and Figure 2 In some embodiments of the present application, the outer contour of the end of the protrusion 21 away from the main body 23 is a first arc surface that protrudes in a direction away from the main body 23 (toward the Y direction).

[0039] Through the above arrangement, the outer contour of the end of the protrusion 21 away from the main body 23 is an arc surface, which can reduce the stress generated when the covering film 2 is bent, which is beneficial to the bending of the covering film 2, thereby reducing the restrictive effect of the covering film 2 on the gold finger 3, so that the gold finger 3 is easy to bend and not easy to crack.

[0040] Furthermore, the first arc surface protrudes toward the direction close to the gold finger 3, so that the first arc surface can guide the flowing anisotropic conductive adhesive, thereby making it easier for excess anisotropic conductive adhesive to flow toward the groove formed between the second conductive contact piece 32, the cover film 2 and the flexible insulating substrate 1, and also facilitates the excess anisotropic conductive adhesive to flow out from between the FPC and the device with the gold finger in a direction parallel to the X direction, so as to prevent the anisotropic conductive adhesive from accumulating on the edge of the raised portion 21.

[0041] In some embodiments of the present application, the radius of the first curved surface is 0.2 mm-0.5 mm.

[0042] The radius of the first arc surface refers to the radius of the inscribed circle of the first arc surface. The smaller the radius, the larger the curvature of the first arc surface, which is more conducive to the anisotropic conductive adhesive flowing along the first arc surface, thereby being more conducive to the excess anisotropic conductive adhesive flowing to the groove formed between the second conductive contact sheet 32, the cover film 2 and the flexible insulating substrate 1, or being more conducive to the excess anisotropic conductive adhesive flowing out from between the FPC and the device with the gold finger.

[0043] In the related art, the covering film 2 is generally manufactured by a stamping process. The smaller the radius of the first arc surface is, the higher the precision requirement for the stamping die is, which makes the manufacturing of the stamping die more difficult.

[0044] Therefore, the embodiment of the present application limits the radius of the first curved surface to 0.2mm-0.5mm. While increasing the curvature of the first curved surface as much as possible, the precision requirements for the stamping die can be reduced to reduce the difficulty of making the stamping die, thereby reducing the production cost of the FPC structure of the embodiment of the present application.

[0045] It should be noted that the radius is a parameter that describes the curvature of the arc surface, and the angle value of the tangent of the arc surface is also a parameter that describes the curvature of the arc surface.

[0046] In some embodiments of the present application, when the curvature of the first curved surface is limited by the angle value of the tangent of the curved surface, the angle value between the straight line parallel to the second direction and the tangent of the first curved surface is required to be 45 degrees to 60 degrees.

[0047] In combination with the above description, it can be seen that by limiting the angle between the straight line parallel to the second direction and the tangent of the first arc surface to 45 degrees-60 degrees, the curvature of the first arc surface can be increased as much as possible while reducing the precision requirements for the stamping die, thereby reducing the difficulty of making the stamping die, thereby reducing the production cost of the FPC structure of the embodiment of the present application.

[0048] Please refer to Figure 1 and Figure 2Specifically, the angle value of the angle between the straight line parallel to the second direction and the tangent of the first arc surface refers to: the angle value of the angle between the tangent of the first arc surface and the X direction (when the angle value of the angle between the tangent of the first arc surface and the X direction is less than 90 degrees), or the angle value of the supplementary angle of the angle between the tangent of the first arc surface and the X direction (when the angle value of the angle between the tangent of the first arc surface and the X direction is greater than 90 degrees).

[0049] In some embodiments of the present application, a plurality of protrusions 21 are provided, and the protrusions 21 are arranged at intervals along the second direction.

[0050] Through the above arrangement, the plurality of first arc surfaces are distributed in the second direction, which is conducive to the excess anisotropic conductive adhesive flowing out from between the FPC and the device having the gold fingers 3 .

[0051] In some embodiments of the present application, the distance between two adjacent protrusions 21 is 1.0 mm-1.5 mm.

[0052] It should be noted that the distance between two adjacent protrusions 21 is one of the parameters affecting the size of the groove formed between the second conductive contact sheet 32, the cover film 2 and the flexible insulating substrate 1. The distance between two adjacent protrusions 21 is also a parameter affecting the difficulty of manufacturing the cover film 2.

[0053] If the distance between two adjacent protrusions 21 is too small, the groove formed between the second conductive contact sheet 32, the cover film 2 and the flexible insulating substrate 1 will be too small to accommodate the excess anisotropic conductive adhesive. It will also increase the precision requirements of the stamping die, making the stamping die more difficult to manufacture. However, if the distance between two adjacent protrusions 21 is too large, the groove formed between the second conductive contact sheet 32, the cover film 2 and the flexible insulating substrate 1 will be too large, resulting in a gap between the FPC and the device with the gold finger, which will affect the stability of the binding structure between the FPC and the device with the gold finger.

[0054] Therefore, by limiting the distance between two adjacent protrusions 21 to 1.0 mm-1.5 mm, the groove formed between the second conductive contact piece 32, the covering film 2 and the flexible insulating substrate 1 can accommodate excess anisotropic conductive adhesive without forming a large gap between the FPC and the device with gold fingers, and without making the precision requirements of the stamping die too high, thereby reducing the difficulty of making the stamping die and thus reducing the production cost of the FPC structure of the embodiment of the present application.

[0055] In some embodiments of the present application, a recessed portion 22 is defined between two adjacent protrusions 21 , and a distance between an end of the recessed portion 22 away from the gold finger 3 and the gold finger 3 is 0.2 mm-0.3 mm.

[0056] It should be noted that if the distance between the gold finger 3 and the recessed portion 22 is too small, the groove formed between the second conductive contact sheet 32, the cover film 2 and the flexible insulating substrate 1 will be too small to accommodate the excess anisotropic conductive adhesive. However, if the distance between the gold finger 3 and the recessed portion 22 is too large, the groove formed between the second conductive contact sheet 32, the cover film 2 and the flexible insulating substrate 1 will be too large, which will cause a gap between the FPC and the device with the gold finger, thereby affecting the stability of the binding structure between the FPC and the device with the gold finger.

[0057] Therefore, the distance between the gold finger 3 and the recessed portion 22 is limited to 0.2 mm-0.3 mm, so that the groove formed between the second conductive contact piece 32, the cover film 2 and the flexible insulating substrate 1 can accommodate excess anisotropic conductive adhesive without forming a large gap between the FPC and the device with the gold finger.

[0058] It should be noted that the distance between the gold finger 3 and the recessed portion 22 can be adjusted according to production requirements.

[0059] Please refer to Figure 2 In some embodiments of the present application, the outer contour of the end of the recessed portion 22 close to the golden finger 3 can be a plane.

[0060] However, the plane is not conducive to the flow of the anisotropic conductive adhesive in the recessed portion 22. When the recessed portion 22 contains too much anisotropic conductive adhesive, the anisotropic conductive adhesive is not easy to flow to the other recessed portions 22, or is not easy to flow out from between the FPC and the device with the gold finger, resulting in excessive accumulation of anisotropic conductive adhesive in individual or all recessed portions 22, thereby causing the possibility of short circuit in the FPC structure.

[0061] Please refer to Figure 1 In some embodiments of the present application, the outer contour of one end of the recessed portion 22 close to the golden finger 3 is a second arc surface convex in a direction away from the golden finger 3 (in a direction opposite to the Y direction).

[0062] Through the above arrangement, the outer contour of the end of the recessed portion 22 close to the gold finger 3 is an arc surface, which can reduce the stress generated when the covering film 2 is bent, which is beneficial to the bending of the covering film 2, thereby reducing the restrictive effect of the covering film 2 on the gold finger 3, so that the gold finger 3 is easy to bend and not easy to crack.

[0063] Furthermore, the second curved surface can also guide the anisotropic conductive adhesive so that too much anisotropic conductive adhesive will not accumulate in the recessed portion 22, thereby preventing a short circuit in the FPC structure.

[0064] Furthermore, through the above arrangement, the first curved surface and the second curved surface cooperate to form a wavy shape, which is conducive to the anisotropic conductive adhesive flowing along the outer contour of the end of the covering film 2 close to the gold finger 3, so as to facilitate the anisotropic conductive adhesive to flow out from between the FPC and the device with the gold finger, and prevent the anisotropic conductive adhesive from accumulating at the outer contour of the end of the covering film 2 close to the gold finger 3.

[0065] In some embodiments of the present application, the radius of the second curved surface is 0.2 mm-0.5 mm.

[0066] It should be noted that the radius of the second curved surface refers to the radius of the inscribed circle of the radius of the second curved surface. The smaller the radius, the larger the curvature of the second curved surface, and the more conducive it is for the anisotropic conductive adhesive to flow along the second curved surface.

[0067] Combined with the above description of the raised portion 21, it can be seen that the embodiment of the present application limits the radius of the second arc surface to 0.2mm-0.5mm. While increasing the curvature of the outer contour of the end of the recessed portion 22 close to the gold finger 3 as much as possible, the precision requirements for the stamping die can be reduced to reduce the difficulty of making the stamping die, thereby reducing the production cost of the FPC structure of the embodiment of the present application.

[0068] In some embodiments of the present application, when the curvature of the second curved surface is limited by the angle value of the tangent of the curved surface, the angle value between the straight line parallel to the second direction and the tangent of the second curved surface is required to be 45 degrees to 60 degrees.

[0069] In combination with the above description, it can be seen that through the above setting, while increasing the curvature of the second curved surface as much as possible, the precision requirements for the stamping die can be reduced to reduce the difficulty of making the stamping die, thereby reducing the production cost of the FPC structure of the embodiment of the present application.

[0070] Please refer to Figure 1 The angle value of the angle between the straight line parallel to the second direction and the tangent of the second arc surface refers to: the angle value of the angle between the tangent of the second arc surface and the X direction (when the angle value of the angle between the tangent of the second arc surface and the X direction is less than 90 degrees), or the angle value of the supplementary angle of the angle between the tangent of the second arc surface and the X direction (when the angle value of the angle between the tangent of the second arc surface and the X direction is greater than 90 degrees).

[0071] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An FPC structure, characterized in that: It includes a flexible insulating substrate, a circuit layer and a cover film which are sequentially stacked along a first direction; The circuit layer includes a gold finger, the gold finger includes a plurality of conductive contact pieces, and the plurality of conductive contact pieces are spaced apart along the second direction; The covering film comprises a main body portion and a protruding portion connected to each other, and in a direction perpendicular to the second direction, the main body portion is located on a side of the protruding portion away from the gold finger, and the protruding portion covers a portion of the conductive contact sheet; The gold finger comprises a plurality of first conductive contacts and a plurality of second conductive contacts, a portion of the first conductive contacts is covered between the cover film and the flexible insulating substrate, and another portion of the first conductive contacts protrudes from the cover film in a direction from the main body to the protruding portion; The second conductive contact piece completely protrudes out of the cover film in a direction from the main body portion to the protruding portion.

2. The FPC structure according to claim 1, characterized in that: The outer contour of the end of the protruding portion away from the main body is a first arc surface protruding in a direction away from the main body.

3. The FPC structure according to claim 2, characterized in that: The radius of the first curved surface is 0.2 mm-0.5 mm.

4. The FPC structure according to claim 2, characterized in that: The angle between a straight line parallel to the second direction and a tangent line of the first arc surface is 45 degrees to 60 degrees.

5. The FPC structure according to any one of claims 1 to 4, characterized in that: A plurality of the protrusions are provided, and the protrusions are arranged at intervals along the second direction.

6. The FPC structure according to claim 5, characterized in that: The distance between two adjacent protrusions is 1.0 mm to 1.5 mm.

7. The FPC structure according to claim 5, characterized in that: A recessed portion is defined between two adjacent protrusions, and a distance between an end of the recessed portion away from the gold finger and the gold finger is 0.2 mm-0.3 mm.

8. The FPC structure according to claim 7, characterized in that: The outer contour of the end of the recessed portion close to the golden finger is a second arc surface convex in a direction away from the golden finger.

9. The FPC structure according to claim 8, characterized in that: The radius of the second curved surface is 0.2 mm-0.5 mm.

10. The FPC structure according to claim 8, characterized in that: The angle between a straight line parallel to the second direction and a tangent line of the second arc surface is 45 degrees to 60 degrees.

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