Flexible circuit board and display device

Abstract

The utility model discloses a kind of flexible circuit board and display device, to improve the line of flexible circuit board bending area in prior art is easily broken, cause the problem of black screen of display product.This embodiment of the utility model provides a kind of flexible circuit board, comprising: first binding part, first binding part has oppositely arranged first surface and second surface, the first binding part is attached with the back light surface of display module by the first surface;Bending part, with the first binding part is connected, with the third surface of the second surface is connected;The bending part is provided with at least one reinforcing structure on the third surface.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor technology, and in particular to a flexible circuit board and a display device. Background Technology

[0002] With the trend of cost reduction in the mid-shell of display products, such as increased proportion of plastic parts, thinner mid-shell, and mid-shell changing from die casting to stamping, the shell's resistance to deformation, flatness, and cushioning have all deteriorated, resulting in a significant decrease in the protection performance of the module. During the drop test of the whole machine, the flexible printed circuit (FPC) showed circuit breakage in the bending area (compared to other areas, the bending area only has a trace layer on one side, making the traces more prone to breakage), which manifested as a black screen. Utility Model Content

[0003] This invention provides a flexible circuit board and a display device to improve the problem of easy breakage of the circuits in the bending area of ​​the flexible circuit board in the prior art, which leads to black screen in the display product.

[0004] This utility model embodiment provides a flexible circuit board, including:

[0005] A first bonding part has a first surface and a second surface disposed opposite to each other, and the first bonding part is attached to the backlight surface of the display module through the first surface;

[0006] The bent portion is connected to the first binding portion and has a third surface connected to the second surface; the bent portion is provided with at least one reinforcing structure on the third surface.

[0007] In one possible implementation, the bending portion includes: a first outer boundary and a second outer boundary extending along a first direction; the reinforcing structure includes: a first reinforcing rib extending along a second direction and a second reinforcing rib extending along a third direction, the first reinforcing rib and the second reinforcing rib intersecting; the second direction intersects the first direction, and the third direction intersects the first direction.

[0008] In one possible implementation, the first reinforcing rib and the second reinforcing rib have an intersection point, and the minimum distance from the intersection point to the first outer boundary is equal to the minimum distance from the intersection point to the second outer boundary.

[0009] In one possible implementation, one end of the first reinforcing rib extends to the first outer boundary and the other end extends to the second outer boundary; the first end of the second reinforcing rib extends to the first outer boundary and the other end extends to the second outer boundary.

[0010] In one possible implementation, the first reinforcing rib intersects with the first outer boundary to form a first included angle and a second included angle, wherein the first included angle is smaller than the second included angle, and the angle range of the first included angle is 30°. o ~90 o ;

[0011] The second reinforcing rib intersects with the first outer boundary to form a third angle and a fourth angle, wherein the third angle is smaller than the fourth angle, and the angle range of the third angle is 30°. o ~90 o ;

[0012] The first reinforcing rib and the second outer reinforcing rib intersect to form a fifth angle and a sixth angle, wherein the fifth angle is smaller than the sixth angle, and the angle range of the fifth angle is 30°. o ~90 o .

[0013] In one possible implementation, the reinforcing structure includes: a reinforcing block having a third outer boundary along an extension direction perpendicular to the bend; at least a portion of the third outer boundary is curved.

[0014] In one possible implementation, the third outer boundary includes: a wavy shape, a semi-circular shape, or a semi-elliptical shape.

[0015] In one possible implementation, the first bonding portion includes: a first substrate, a first wiring layer, a first adhesive layer, and a first cover film stacked on one side of the first substrate, and a second wiring layer, a second adhesive layer, and a second cover film stacked on the other side of the first substrate; the first surface includes at least a portion of the first cover film on the side facing away from the first adhesive layer, and the second surface includes at least a portion of the second cover film on the side facing away from the second adhesive layer.

[0016] The bending portion includes: a second substrate, a third wiring layer stacked on one side of the second substrate, a third adhesive layer, and a third cover film; the second substrate and the first substrate are of the same layer and material, the third wiring layer and the first wiring layer are of the same layer and material, the third adhesive layer and the first adhesive layer are of the same layer and material, and the third cover film and the first cover film are of the same layer and material.

[0017] In one possible implementation, the reinforcing structure includes: a first adhesive portion and a first covering portion stacked together;

[0018] The first adhesive portion and the second adhesive layer are made of the same material and layer, and the first covering portion and the second covering film are made of the same material and layer.

[0019] In one possible implementation, the flexible circuit board further includes: a plurality of through holes located at the bend, the through holes penetrating the second substrate, the third wiring layer, the third adhesive layer, and the third cover film.

[0020] In one possible implementation, the third routing layer has multiple routing groups; the via is located between two adjacent routing groups.

[0021] In one possible implementation, the orthographic projection of the via on the second substrate does not overlap with the orthographic projection of the reinforcing structure on the second substrate.

[0022] In one possible implementation, the shape of the through hole includes: ellipse, circle, triangle, square, rectangle, trapezoid, or rhombus.

[0023] In one possible implementation, the bent portion includes: a first outer boundary extending in a first direction;

[0024] The through hole is elliptical in shape, and the extended line of the major axis of the ellipse intersects the first outer boundary to form a seventh angle and an eighth angle, wherein the seventh angle is smaller than the eighth angle, and the angle range of the seventh angle is 30°. o ~60 o ;

[0025] Alternatively, the through hole may be rhomboid in shape, with one side of the rhombus intersecting the first outer boundary to form a ninth angle and a tenth angle, wherein the ninth angle is smaller than the tenth angle, and the angle range of the ninth angle is 30°. o ~60 o .

[0026] In one possible implementation, the third routing layer includes: at least one first routing trace; the first routing trace includes: a first routing trace segment, a second routing trace segment, and a third routing trace segment;

[0027] The first routing segment includes: multiple first sub-routes extending along the fourth direction; the third routing segment includes: a second routing line extending along the fourth direction; the second routing segment includes: at least two connecting routing lines, one end of which is connected to the first sub-routes and the other end of which is connected to the second routing line.

[0028] The connecting traces are arc-shaped.

[0029] In one possible implementation, at the connection point between the connecting trace and the first trace, the tangent of the connecting trace intersects the extension of the second trace to form an eleventh angle and a twelfth angle, wherein the eleventh angle is smaller than the twelfth angle, and the eleventh angle has an angle range of 60°.o ~80 o .

[0030] This utility model also provides a display device, including: a display module, and a flexible circuit board as described in this utility model;

[0031] The display module has a light-emitting surface and a backlight surface;

[0032] The flexible circuit board further includes: a second bonding portion; the bending portion is located between the first bonding portion and the second bonding portion; the first bonding portion is bonded to the backlight surface of the display module; and the second bonding portion is bonded to the light-emitting surface of the display module.

[0033] In one possible implementation, the bending portion further includes: a fourth wiring layer, a fourth adhesive layer, and a fourth cover film stacked on the other side of the second substrate; the fourth wiring layer is of the same layer and material as the second wiring layer, the fourth adhesive layer is of the same layer and material as the second adhesive layer, and the fourth cover film is of the same layer and material as the second cover film.

[0034] The display device further includes: a gasket; the gasket includes: a gasket body and a gasket protrusion;

[0035] The display module further includes: a side surface connecting the display surface and the backlight surface; the first binding part is attached to the backlight surface of the display module through the gasket body, and the bent part is attached to the side surface of the display module through at least a portion of the outward protrusion of the gasket.

[0036] In one possible implementation, the length of the gasket protrusion in the first direction is equal to the length of the flexible circuit board in the first direction;

[0037] The length of the convex portion of the pad in the second direction is greater than or equal to the thickness of the display module in the direction perpendicular to the second substrate.

[0038] In one possible implementation, the gasket is double-sided adhesive.

[0039] The beneficial effects of this utility model embodiment are as follows: In this utility model, the bending part is provided with at least one reinforcing structure on the third surface, that is, at least one reinforcing structure is provided on the side of the bending part where no wiring layer is provided, which not only ensures that the overall film layer of the bending part is thin and the rebound force is low, but also improves the strength of the bending part, and improves the problem that the bending part is prone to wire breakage and black screen during the whole machine mechanical test. Attached Figure Description

[0040] Figure 1A top view of the flexible circuit board bonded to the display module without bending.

[0041] Figure 2A for Figure 4A A schematic diagram of a cross-section along the dashed line e1;

[0042] Figure 2B for Figure 4A A schematic diagram of a specific cross-section along the dashed line e1;

[0043] Figure 2C for Figure 4A Another specific cross-sectional diagram along the dashed line e1;

[0044] Figure 3A This is a partial cross-sectional view of a flexible circuit board after it has been bent and bonded to a display module.

[0045] Figure 3B This is a partial cross-sectional view of a specific flexible circuit board after it has been bent and bound to a display module.

[0046] Figure 4A for Figure 1 One of the enlarged views of the back side at the dashed box S1;

[0047] Figure 4B for Figure 4A A magnified view of a portion of the image;

[0048] Figure 5A for Figure 1 The second enlarged view of the back side at the dashed box S1;

[0049] Figure 5B for Figure 5A A magnified view of a portion of the image;

[0050] Figure 6A One of the schematic diagrams showing a through hole provided in the bent portion of this utility model embodiment;

[0051] Figure 6B for Figure 6A A cross-sectional schematic diagram;

[0052] Figure 6C A second schematic diagram showing a through hole provided in the bent portion of this utility model embodiment;

[0053] Figure 7 A third schematic diagram showing a through hole provided in the bent portion of this utility model embodiment;

[0054] Figure 8 This is a schematic diagram of the wiring at the bend.

[0055] Figure 9AThis is a schematic diagram showing the double-layered wiring at the bend.

[0056] Figure 9B This is a schematic diagram showing the positions of the gasket and the light-shielding adhesive layer.

[0057] Figure 9C This is a schematic diagram showing the spacer being bent and attached to the side of the display module.

[0058] Figure 10 This is a schematic diagram of a flexible circuit board attached to a display module using spacers. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0060] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0061] As used herein, “approximately” or “substantially the same” includes the stated value and means within an acceptable range of deviations from the specific value, as determined by a person skilled in the art taking into account the measurement in question and the errors associated with the measurement of the specific quantity (i.e., limitations of the measurement system). For example, “substantially the same” may mean a difference relative to the stated value within one or more standard deviations, or within ±30%, 20%, 10%, or 5%.

[0062] In the accompanying drawings, the thicknesses of layers, films, panels, regions, etc., are enlarged for clarity. Exemplary embodiments are described herein with reference to cross-sectional views that are schematic diagrams of idealized embodiments. Thus, deviations from the shapes shown in the drawings will be expected as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but rather include deviations in shape caused, for example, by manufacturing processes. For example, regions illustrated or described as flat may typically have rough and / or non-linear characteristics. Furthermore, sharp corners illustrated may be rounded. Thus, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0063] To keep the following description of the embodiments of this disclosure clear and concise, detailed descriptions of known functions and known components are omitted.

[0064] The display product includes: a display panel, a cover plate on the light-emitting side of the display panel, a backlight assembly on the backlight side of the display panel, and a housing on the side of the backlight assembly facing away from the display panel; the upper side of the flexible circuit board is fixed to the display panel, and the lower side is fixed to the backlight assembly by double-sided adhesive; the main mechanisms of circuit breakage in the bending area of ​​the flexible circuit board during the drop test of the entire display product terminal include: when the whole device is dropped and impacted from the side or corner, the deformed housing squeezes the backlight assembly, causing the backlight assembly to slightly shift or rotate relative to the cover plate; during the rotation or movement of the backlight assembly, the flexible circuit board is pulled, and stress concentration is easily generated on the flexible circuit board (for example, at the boundary of the adhesive layer); ultimately manifested as circuit breakage in a single layer area.

[0065] See Figure 1 , Figures 2A-2C , Figures 3A-3B , Figure 4A , Figure 5A As shown, where, Figure 1 This is a top view of the flexible circuit board bonded to the display module without bending. Figure 2A This is a partial cross-sectional view of a flexible circuit board when it is not bent. Figure 2B This is a partial cross-sectional view of a specific flexible circuit board when it is not bent. Figure 2C This is a partial cross-sectional view of another specific flexible circuit board when it is not bent. Figure 3A This is a partial cross-sectional view of a flexible circuit board after it has been bent and bonded to a display module. Figure 3B This is a partial cross-sectional view of a specific flexible circuit board after it has been bent and bonded to a display module. Figure 4A for Figure 1 One of the enlarged partial views of the back side at the dashed box S1. Figure 5A for Figure 1In the second enlarged schematic diagram of the back side at the dashed frame S1, this embodiment of the present invention provides a flexible circuit board 1, comprising:

[0066] The first bonding part B1 has a first surface A1 and a second surface A2 that are disposed opposite to each other. The first bonding part B1 is attached to the backlight surface A02 of the display module 100 through the first surface A1.

[0067] The bent portion W is connected to the first binding portion B1 and has a third surface A3 connected to the second surface A2; the bent portion W is provided with at least one reinforcing structure D on the third surface A3.

[0068] In related technologies, to reduce the rebound force of the bent portion W of the flexible circuit board 1 after bending, the bent portion W is usually provided with a wiring layer on only one side. However, this arrangement reduces the strength of the flexible circuit board 1 at the bent portion W, which may cause the wiring at the bent portion W to break easily during the mechanical testing of the whole machine. In this utility model, the bent portion W is provided with at least one reinforcing structure D on the third surface A3. That is, at least one reinforcing structure D is provided on the side of the bent portion W where no wiring layer is provided. This ensures that the overall film layer of the bent portion W is thinner and the rebound force is lower, while also improving the strength of the bent portion W. This improves the problem of the bent portion W being prone to breakage and causing black screen during the mechanical testing of the whole machine.

[0069] In one possible implementation, combined with Figure 2A , Figure 3A As shown, the first bonding part B1 can be a double-layer wiring design, and the bending part W can be a single-layer wiring design. That is, the thickness of the flexible circuit board at the bending part W1 is less than the thickness of the first bonding part B1, and the flexible circuit board forms a depression at the bending part W.

[0070] In one possible implementation, combined with Figure 2A , Figure 3A As shown, the display module 100 has a light-emitting surface A01 and a backlight surface A02; the flexible circuit board 1 further includes: a second bonding portion B2; a bending portion W1 located between the first bonding portion B1 and the second bonding portion B2; the first bonding portion B1 is bonded to the backlight surface A02 of the display module 100; and the second bonding portion B2 is bonded to the light-emitting surface A01 of the display module 100.

[0071] In one possible implementation, the reinforcing structure D can be an X-shaped reinforcing rib, see [reference needed]. Figure 4A , Figure 4BAs shown, specifically, the bending portion W includes: a first outer boundary f1 and a second outer boundary f2 extending along the first direction X; the reinforcing structure D includes: a first reinforcing rib D1 extending along the second direction Z1 and a second reinforcing rib D2 extending along the third direction Z2, the first reinforcing rib D1 and the second reinforcing rib D2 intersect; the second direction Z1 intersects the first direction X, and the third direction Z2 intersects the first direction X.

[0072] In one possible implementation, see Figure 4A , Figure 4B As shown, the first reinforcing rib D1 and the second reinforcing rib D2 intersect at a point O. The minimum distance d1 from the intersection point O to the first outer boundary f1 is equal to the minimum distance d2 from the intersection point O to the second outer boundary f2. That is, in the direction perpendicular to the first direction X, the intersection point O is located at the middle position of the bent portion W. In this invention, the intersection point O of the first reinforcing rib D1 and the second reinforcing rib D2 being located at the middle position of the bent portion W is beneficial for symmetrically distributing the supporting strength of the reinforcing ribs in the direction perpendicular to the first direction X, effectively improving the overall strength of the bent portion W.

[0073] In one possible implementation, see Figure 4A , Figure 4B As shown, one end of the first reinforcing rib D1 extends to the first outer boundary f1, and the other end extends to the second outer boundary f2; the second reinforcing rib D2 extends to the first outer boundary f1, and the other end extends to the second outer boundary f2. This strengthens the overall support strength of the bent portion W perpendicular to the first direction X.

[0074] In one possible implementation, see Figure 4A , Figure 4B As shown, the first reinforcing rib D1 intersects with the second outer boundary f2 to form a first included angle α1 and a second included angle α2, wherein the first included angle α1 is smaller than the second included angle α2, and the angle range of the first included angle α1 is 30°. o ~90 o Optionally, the first included angle α1 is 30°. o 35 o 40 o 45 o 50 o 55 o , or 60 o The second reinforcing rib D2 intersects with the second outer boundary f2 to form a third included angle α3 and a fourth included angle α4, wherein the third included angle α3 is smaller than the fourth included angle α4, and the angle range of the third included angle α3 is 30°. o ~90 o Optionally, the included angle α3 is 30°. o 35 o 40 o 45 o 50 o 55 o , or 60 o The first reinforcing rib D1 and the second outer reinforcing rib D2 intersect to form a fifth included angle α5 and a sixth included angle α6, wherein the fifth included angle α5 is smaller than the sixth included angle α6, and the angle range of the fifth included angle α5 is 30°. o ~90 o Optionally, the included angle α5 is 30 degrees. o 35 o 40 o 45 o 50 o 55 o , or 60 o .

[0075] In one possible implementation, see Figure 4B As shown, the maximum spacing a1 between the first reinforcing rib D1 and the second outer reinforcing rib D2 in the first direction X can range from 2 mm to 3 mm. This reduces the rebound force of the bent portion W while simultaneously increasing its strength, thus mitigating the problems of wire breakage and black screen issues that easily occur during mechanical testing of the entire machine.

[0076] In one possible implementation, see Figure 4B As shown, the distance between the first reinforcing rib D1 and the second outer reinforcing rib D2 perpendicular to the first direction X can be equal to the width of the bent portion W; the maximum spacing a2 between the first reinforcing rib D1 and the second outer reinforcing rib D2 perpendicular to the first direction X can range from 1.5 mm to 2.5 mm, for example, it can be 1.8 mm, 1.9 mm, 1.95 mm, or 2.0 mm. This is to avoid the problem that if the maximum spacing a2 between the first reinforcing rib D1 and the second outer reinforcing rib D2 perpendicular to the first direction X is too large, it will affect the normal bending of the bent portion W, and to avoid the problem that if the maximum spacing a2 between the first reinforcing rib D1 and the second outer reinforcing rib D2 perpendicular to the first direction X is too small, it will cause insufficient overall support strength of the bent portion W perpendicular to the first direction X.

[0077] In one possible implementation, see Figure 4B As shown, the dimension a3 of the first reinforcing rib D1 perpendicular to its extension direction can range from 0.05 mm to 0.3 mm, for example, it can be 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, or 0.3 mm. This is to avoid excessive rebound force if the dimension a3 of the first reinforcing rib D1 perpendicular to its extension direction is too large, and to avoid insufficient strength of the bent portion W if the dimension a3 of the first reinforcing rib D1 perpendicular to its extension direction is too small.

[0078] In one possible implementation, the number of reinforcing ribs can be adjusted according to the width of the bent portion W, and the spacing between adjacent reinforcing ribs can be in the range of 8 mm to 9 mm; optionally, for example, the number of reinforcing ribs is 4, as too many reinforcing ribs will cause excessive rebound force.

[0079] In one possible implementation, the reinforcing structure D can be a corrugated reinforcing rib, as detailed below. Figure 5A , Figure 5B As shown, the reinforcing structure D includes a reinforcing block having a third outer boundary f3 along the extension direction perpendicular to the bending portion W; at least a portion of the third outer boundary f3 is curved. In this invention, the curved shape of at least a portion of the third outer boundary f3 of the reinforcing block improves the strength of the bending portion W and also allows the bending portion W to have better bending performance in the extension direction perpendicular to the bending portion W.

[0080] In one possible implementation, see Figure 5A , Figure 5B As shown, the third outer boundary f3 includes: wavy, semi-circular, or semi-elliptical shapes.

[0081] In another possible implementation, the shape of the third outer boundary f3 can also be a bent line or a shape formed by multiple bows connected in sequence.

[0082] In one possible implementation, see Figure 5A , Figure 5B As shown, the minimum spacing a5 between adjacent reinforcing blocks in the first direction X can be 0.4 mm to 0.5 mm.

[0083] In one possible implementation, see Figure 5A , Figure 5B As shown, in the direction perpendicular to the first direction X, the dimension a4 of the reinforcing block d can be less than or equal to the width of the bent portion W; the dimension a4 of the reinforcing block d in the direction perpendicular to the first direction X can range from 1.5 mm to 2.5 mm, for example, it can be 1.8 mm, 1.9 mm, 1.95 mm or 2.0 mm.

[0084] In one possible implementation, see Figure 2B , Figure 3BAs shown, the first bonding portion B1 includes: a first substrate 101, a first wiring layer 102, a first adhesive layer 103, and a first cover film 104 stacked on one side of the first substrate 101, and a second wiring layer 105, a second adhesive layer 106, and a second cover film 107 stacked on the other side of the first substrate 101; the first surface A1 includes at least a portion of the surface of the first cover film 104 facing away from the first adhesive layer 103, and the second surface A2 includes at least a portion of the surface of the second cover film 107 facing away from the second adhesive layer 106;

[0085] The bending portion W includes: a second substrate 201, a third wiring layer 202 stacked on one side of the second substrate 201, a third adhesive layer 203, and a third cover film 204; the second substrate 201 is in the same layer and made of the same material as the first substrate 101, the third wiring layer 202 is in the same layer and made of the same material as the first wiring layer 102, the third adhesive layer 203 is in the same layer and made of the same material as the first adhesive layer 103, and the third cover film 204 is in the same layer and made of the same material as the first cover film 104.

[0086] In one possible implementation, see Figure 2B As shown, the third surface A3 may include at least a portion of the surface of the second substrate 201 facing away from the third wiring layer 202.

[0087] In one possible implementation, see Figure 2C As shown, the extension length of the first adhesive layer 103 and the first cover film 104 towards the second bonding portion B2 can be less than the extension length of the first wiring layer 102. For example, the outer edges of the first adhesive layer 103 and the first cover film 104 can be located in the area where the bending portion W is located. The flexible circuit board also includes a green oil layer 108 covering the edge areas of the first adhesive layer 103 and the first cover film 104 to protect the first wiring layer 102 and prevent it from being corroded. Optionally, the first bonding portion B1 may also include a shielding layer 109 located on the side of the second cover film 107 facing away from the second adhesive layer 106 to shield signals and prevent signal interference from the entire device.

[0088] In one possible implementation, when the flexible circuit board also includes other film layers, the first surface A1 and / or the second surface A2, and / or the third surface A3 may also be surfaces of other film layers. For example, the first surface A1 may also include at least a portion of the green oil layer 108 on the surface opposite to the second cover film 107; the second surface A2 may include at least a portion of the shielding layer 109 on the surface opposite to the second cover film 107.

[0089] Optionally, the materials of the first substrate 101 and the second substrate 201 may include polyimide film (PI), which can serve as the carrier film of the flexible circuit board; optionally, the materials of the first wiring layer 102, the second wiring layer 105, and the third wiring layer 202 may include copper, which may mainly include electrolytic copper and rolled copper, for etching circuits; the first adhesive layer 103, the second adhesive layer 106, and the third adhesive layer 203 can serve as adhesives, respectively used to bond adjacent layers; the first cover film 104, the second cover film 107, and the third cover film 204 can be used as surface covers, providing insulation and protection.

[0090] In one possible implementation, see Figure 2B As shown, the reinforcing structure D includes: a first adhesive portion D01 and a first covering portion D02 stacked together; the first adhesive portion D01 is in the same layer and made of the same material as the second adhesive layer 106, and the first covering portion D02 is in the same layer and made of the same material as the second covering film 107. In this invention, the first adhesive portion D01 and the second adhesive layer 106 are in the same layer and made of the same material, and the first covering portion D02 and the second covering film 107 are in the same layer and made of the same material. The first corner portion D01 can be formed at the same time as the second adhesive layer 106, and the first covering portion D02 can be formed at the same time as the second covering film 107. This can be achieved through a lamination process without increasing costs.

[0091] The thickness of the first adhesive portion D01 can range from 10μm to 20μm; the thickness of the second cover film 107 can range from 10μm to 20μm; the thickness of the first adhesive portion D01 can be equal to the thickness of the second cover film 107; the thickness of the first adhesive portion D01 can be equal to the thickness of the second adhesive layer 106; the thickness of the first cover portion D02 can be equal to the thickness of the second cover film 107.

[0092] To assess the degree of stress concentration, the inventors of this utility model have established a method for evaluating the shear resistance of materials, i.e., the magnitude of stress: a slip-shear test, which records the number of slips when the flexible circuit board's bent portion W breaks; the more slips, the stronger its shear resistance; the test method is as follows:

[0093] A 30mm wide flexible circuit board test strip was prepared. The copper layer of the strip was etched and coated with solder mask to ensure consistency with the single-layer area. The test strip was then held in place on a solid surface with a 15mm gap between the upper and lower fixing blocks. The two fixing blocks were then joined together, causing the test strip to bend in an S-shape in the Y direction. The cam mechanism was adjusted to ensure a 2mm difference between the maximum stroke and the minimum forming gap. The equipment was started to perform X-axis reciprocating motion, and the number of failures was recorded. Table 1 below shows the test strip rubbing test and rebound force test, recording the rebound force value of the flexible circuit board and the number of rubbing attempts during tearing. Simulation and physical test results show that adding reinforcing ribs improves the strength of the bent portion of the flexible circuit, but increases the rebound force. The increase in rebound force can be controlled by adjusting the number of reinforcing ribs.

[0094] Table 1:

[0095]

[0096] In one possible implementation, see Figure 6A , Figure 6B As shown, the flexible circuit board also includes: a plurality of through holes K located in the bending portion W, the through holes K penetrating the second substrate 201, the third wiring layer 202, the third adhesive layer 203, and the third cover film 204.

[0097] In related technologies, flexible circuit boards are prone to stress concentration at adhesive layers (e.g., first adhesive layer, second adhesive layer, third adhesive layer), cover films (first cover film, second cover film, third cover film), and teardrop-shaped trace locations. When the flexible circuit board is subjected to tension during mechanical testing of the entire machine, the stress concentration area has already experienced circuit breakage, resulting in a black screen. In this utility model, the flexible circuit board also includes multiple through holes K located at the bend W, which can improve the problem of stress concentration at the bend W of the flexible circuit board and the easy occurrence of circuit breakage when stretched.

[0098] In one possible implementation, see Figure 6B As shown, the orthographic projection of the through hole K onto the second substrate 201 does not overlap with the orthographic projection of the reinforcing structure D onto the second substrate 201.

[0099] In one possible implementation, see Figure 6C As shown, Figure 6C This can be a schematic diagram of the bent portion W on the side opposite to the third surface A3. The third routing layer 202 has multiple routing groups Z; the via K is located between two adjacent routing groups Z. In this way, the via K avoids the routing group Z, thus preventing the routing from breaking due to the placement of the via K.

[0100] In one possible implementation, the shape of the through hole K includes: ellipse, circle, triangle, square, rectangle, trapezoid, or rhombus.

[0101] In one possible implementation, see Figure 6A , Figure 6C As shown, the bent portion W includes: a first outer boundary f1 extending along the first direction X; see also Figure 6A As shown, the through hole K is elliptical in shape. The extension of the major axis k1 of the ellipse intersects with the first outer boundary f1 to form a seventh included angle α7 and an eighth included angle α8. The seventh included angle α7 is smaller than the eighth included angle α8, and the angle range of the seventh included angle α7 is 30°. o ~60 o Or, see Figure 7 As shown, the through hole is rhomboid in shape. The extension of one side of the rhombus intersects the first outer boundary f1 to form a ninth included angle α9 and a tenth included angle α10. The ninth included angle α9 is smaller than the tenth included angle α10, and the angle range of the ninth included angle α9 is 30°. o ~60 o In this invention, the through hole K can be shaped like an inclined rhombus or an ellipse, with the inclination angle ranging from 30°. o ~60 o In this way, the projected width of the through hole K in the first direction X can be increased as much as possible, and the stress concentration problem of the bent part W in the first direction X can be reduced to the greatest extent.

[0102] Optionally, the location and size of the cutout depend on the location and size of the non-trace area. For example, for an elliptical via K, see [reference needed]. Figure 6A As shown, the maximum dimension b1 of the elliptical through-hole K in the direction perpendicular to the extension line k1 of the major axis can range from 0.1 mm to 0.6 mm, for example, it can be 0.5 mm, 0.55 mm, 0.56 mm, 0.57 mm, or 0.6 mm; the maximum dimension b2 of the elliptical through-hole K in the direction parallel to the extension line k1 of the major axis can range from 0.5 mm to 1.5 mm, for example, it can be 1.0 mm, 1.02 mm, or 1.1 mm; the number of through holes K is 2 to 5; see also Figure 7 As shown, when the through hole K is rhomboid, the dimension b2 of the through hole K in the direction parallel to the first direction X can range from 0.5 mm to 1.0 mm; for example, it can be 0.6 mm, 0.7 mm, or 0.8 mm; the number of through holes K is 2 to 5.

[0103] The effectiveness of the design was evaluated by finite element simulation and physical testing of the rebound force and shear resistance. The test results are shown in Table 2 below. The results show that the rebound force decreases after adding the hole design; the shear resistance and bending zone stress are also improved compared to the original design; the hole can be achieved by flexible circuit board punching process without increasing costs.

[0104] Table 2:

[0105] .

[0106] In one possible implementation, see Figure 8 As shown, the third routing layer 202 includes: at least one first routing trace Z1; the first routing trace Z1 includes: a first routing segment Z11, a second routing segment Z12, and a third routing segment Z13; the first routing segment Z11 includes: multiple first sub-routes Z110 extending along the fourth direction Y; the third routing segment Z13 includes: a second routing trace Z130 extending along the fourth direction Y; the second routing segment Z12 includes: at least two connecting traces Z120, one end of which is connected to the first sub-routes Z110, and the other end of which is connected to the second routing trace Z130; the connecting traces Z120 are arc-shaped. Optionally, the fourth square Y can be perpendicular to the first direction X.

[0107] In related technologies, in order to improve the problem of increased rebound force at the bends caused by dense wiring, the wiring is mostly designed as a two-in-one or three-in-one (i.e., a "teardrop" shaped design). However, this design is prone to stress concentration problems and may break when subjected to external pulling force. In this utility model, the connecting wiring Z120 is arc-shaped, that is, it is an arc-shaped transition connection wiring design, which can effectively avoid stress concentration problems at the junction.

[0108] In one possible implementation, see Figure 8 As shown, at the connection point between the connecting trace Z120 and the first trace Z110, the tangent k2 of the connecting trace Z120 intersects the extension of the second trace Z130, forming an eleventh angle α11 and a twelfth angle α12. The eleventh angle α11 is smaller than the twelfth angle α12, and the angle range of the eleventh angle α11 is 60 degrees. o ~80 o .

[0109] When the teardrop-shaped connection trace Z120 is designed as an arc shape, the actual test results are shown in the table below. When the flexible circuit board connection trace Z120 is designed as an arc shape, the shear resistance is also improved.

[0110] Table 3:

[0111]

[0112] Based on the same concept, this utility model also provides a display device, including: a display module 100, and a flexible circuit board 1 as provided in this utility model. In specific implementations, in the embodiments of this disclosure, the display device can be any product or component with display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, or navigator. Other essential components of this display device are those that should be understood by those skilled in the art, and will not be described in detail here, nor should they be construed as limiting this disclosure.

[0113] In one possible implementation, see Figure 9A As shown, the bent portion W further includes: a fourth wiring layer 205, a fourth adhesive layer 206, and a fourth cover film 207 stacked on the other side of the second substrate 201; the fourth wiring layer 205 is in the same layer and made of the same material as the second wiring layer 105, the fourth adhesive layer 206 is in the same layer and made of the same material as the second adhesive layer 106, and the fourth cover film 207 is in the same layer and made of the same material as the second cover film 107.

[0114] See Figures 9B-9C , Figure 10 As shown, the display device also includes: a gasket 3; the gasket 3 includes: a gasket body 31 and a gasket protrusion 32;

[0115] The display module 100 further includes: a side surface A03 connecting the display surface A01 and the backlight surface A02; a first binding part B1 is attached to the backlight surface A02 of the display module 100 via a gasket body 31, and a bent part W is attached to the side surface A03 of the display module 100 via at least a portion of the gasket protrusion 32.

[0116] In related technologies, in order to reduce the rebound force after the flexible circuit board is folded back, i.e. the bending radius, the flexible circuit board bending part is only provided with a wiring layer on one side (i.e., a single-layer area structure is adopted), but this reduces the strength of the flexible circuit board bending part, making it the weakest area of ​​the entire flexible circuit board. In this utility model, the bending part W can also be set as a double-layer wiring structure, i.e., the single-layer area structure is eliminated. However, the elimination of the single-layer area will increase the bending rebound force of the flexible circuit board, thereby increasing the bending radius, which poses a risk of difficulty in assembling the display module and the housing. Therefore, this utility model further proposes that the gasket 3 includes a gasket body 31 and a gasket protrusion 32. The flexible circuit board 1 is bonded to the display module 100 by the gasket 3 using a strong adhesive + edge wrapping method, which achieves the purpose of reducing the bending radius. That is, while having better bending performance, the bending part W can also have better strength and is less prone to wire breakage.

[0117] In one possible implementation, the gasket 3 is double-sided adhesive, with an adhesion of ≥1500gf to the bonding surface of the flexible circuit board 1, and a thickness ranging from 0.05 mm to 0.07 mm, which can be adjusted according to the Z-axis gap between the display panel 10 and the backlight; combined with Figure 10 As shown, the bending radius r (which can be the distance between the outer edge of the flexible circuit board 1 on the side away from the display module 100 and the outer edge of the array substrate 11 in the first direction X) can be reduced from the conventional 1.05 mm to 0.5 mm to 1 mm; for example, it can be 0.5 mm, 0.6 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.9 mm, or 1.0 mm.

[0118] In one possible implementation, combined with Figure 10 As shown, the display module 100 includes: a display panel 10, a cover plate 4 located on the light-emitting side of the display panel 10, and a backlight assembly 20 located on the backlight side of the display panel 10; wherein, the display panel 10 includes: an array substrate 11 and a counter substrate 12 disposed opposite to each other, a first polarizer 13 attached to the counter substrate 12 on the side away from the array substrate 11, and a second polarizer 14 attached to the array substrate 11 on the side away from the counter substrate 12; the backlight assembly 20 includes: a frame 15, an iron frame 16 located on the side of the frame 15 away from the display panel 10, and a light-shielding adhesive layer 17 attached between the frame 15 and the second polarizer 14; an optical adhesive layer 5 is also disposed between the display panel 10 and the cover plate 4; the display device may include: a first flexible circuit board, a second flexible circuit board 2, a control chip IC, and a backlight barrier 6; wherein, the first flexible circuit board may be Figure 1 , Figures 2A-2B , Figures 3A-3B , Figure 4A , Figure 5A The flexible circuit board 1 shown can be the main flexible circuit board of the display device; the second flexible circuit board 2 can be used to provide signals to the backlight assembly 20.

[0119] It should be understood that, since the display module 100 includes multiple structures, the display surface A01 may include partial surfaces of multiple structures, the backlight surface A02 may include partial surfaces of multiple structures, and the side surface A03 may include partial surfaces of multiple structures. For example, the display surface A01 may include a partial surface of the array substrate 11 facing away from the second polarizer 14; the second bonding portion B2 of the flexible circuit board 1 may be attached to a partial surface of the array substrate 11 facing away from the second polarizer 14; the backlight surface A02 may include a partial surface of the housing 16 facing away from the backlight assembly 20, and the first bonding portion B1 may be bonded to a partial surface of the housing facing away from the backlight assembly 20; the side surface A03 may include a partial side surface of the backlight assembly 20 and a partial side surface of the housing 16, and the bending portion 3 is attached to a partial side surface of the backlight assembly 20 and a partial side surface of the housing 16 through the outward protrusion of the gasket 32.

[0120] In one possible implementation, combined with Figure 10 As shown, the outer protrusion 32 of the gasket can not only be attached to the side A03 of the display module 100, but can also be further bent and attached to the surface of the light-shielding adhesive layer 17 on the side away from the backlight assembly 20.

[0121] In one possible implementation, see Figure 9B As shown, the length c1 of the outer protrusion 32 of the spacer in the first direction X is equal to the length of the flexible circuit board 1 in the first direction X (not shown in the figure); the length c2 of the outer protrusion 32 of the spacer in the fourth direction Y is greater than or equal to the thickness of the display module 100 in the direction perpendicular to the second substrate 201 (not shown in the figure). Alternatively, in the embodiment, see [reference needed]. Figure 9B As shown, the length c1 of the outer protrusion 32 of the gasket in the first direction X can range from 20 mm to 40 mm; for example, it can be 20 mm, 25 mm, 30 mm, 35 mm, or 40 mm; the length c2 of the outer protrusion 32 of the gasket in the fourth direction Y can range from 0.5 mm to 1.0 mm; for example, it can be 0.5 mm, 0.6 mm, 0.7 mm, 0.75 mm, or 0.8 mm.

[0122] The protruding position of the outer protrusion 32 of the gasket corresponds to the bonding position of the flexible circuit board 1. The folding process of the gasket 3 can be performed after the backlight factory applies the light-shielding adhesive layer 17. In the backlight shipping state, the gasket 3 should be covered with a shipping protective film 34. The outer protrusion 32 of the gasket and the backlight shipping film 34 are designed as an integral part. Figure 9B A pre-cut line is designed at the bending position of gasket 3, which is folded back together with gasket 3, as shown in the figure. Figure 9C As shown.

[0123] When the bending portion W of the flexible circuit board 1 adopts a double-layer design, the shear resistance is significantly improved, as shown in Table 4 below; this solution can be achieved with a process change without increasing costs.

[0124] Table 4

[0125]

[0126] Although preferred embodiments of this disclosure have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this disclosure.

[0127] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A flexible circuit board, characterized in that, include: A first bonding part has a first surface and a second surface disposed opposite to each other, and the first bonding part is attached to the backlight surface of the display module through the first surface; The first bonding portion includes: a first substrate, a first wiring layer, a first adhesive layer, and a first cover film stacked on one side of the first substrate, and a second wiring layer, a second adhesive layer, and a second cover film stacked on the other side of the first substrate; the first surface includes at least a portion of the first cover film on the side facing away from the first adhesive layer, and the second surface includes at least a portion of the second cover film on the side facing away from the second adhesive layer. The bent portion is connected to the first binding portion and has a third surface connected to the second surface; the bent portion is provided with at least one reinforcing structure on the third surface.

2. The flexible circuit board as described in claim 1, characterized in that, The bending portion includes a first outer boundary and a second outer boundary extending along a first direction; the reinforcing structure includes a first reinforcing rib extending along a second direction and a second reinforcing rib extending along a third direction, the first reinforcing rib and the second reinforcing rib intersecting; the second direction intersects the first direction, and the third direction intersects the first direction.

3. The flexible circuit board as described in claim 2, characterized in that, The first reinforcing rib and the second reinforcing rib have an intersection point, and the minimum distance from the intersection point to the first outer boundary is equal to the minimum distance from the intersection point to the second outer boundary.

4. The flexible circuit board as described in claim 2, characterized in that, One end of the first reinforcing rib extends to the first outer boundary, and the other end extends to the second outer boundary; the first end of the second reinforcing rib extends to the first outer boundary, and the other end extends to the second outer boundary.

5. The flexible circuit board as described in claim 4, characterized in that, The first reinforcing rib intersects with the first outer boundary to form a first included angle and a second included angle, wherein the first included angle is smaller than the second included angle, and the angle range of the first included angle is 30°. o ~90 o ; The second reinforcing rib intersects with the first outer boundary to form a third angle and a fourth angle, wherein the third angle is smaller than the fourth angle, and the angle range of the third angle is 30°. o ~90 o ; The first reinforcing rib and the second reinforcing rib intersect to form a fifth angle and a sixth angle, wherein the fifth angle is smaller than the sixth angle, and the angle range of the fifth angle is 30°. o ~90 o .

6. The flexible circuit board as described in claim 1, characterized in that, The reinforcing structure includes: a reinforcing block having a third outer boundary along an extension direction perpendicular to the bending portion; at least a portion of the third outer boundary is curved.

7. The flexible circuit board as described in claim 6, characterized in that, The third outer boundary includes: wavy, semi-circular, or semi-elliptical shapes.

8. The flexible circuit board according to any one of claims 1-7, characterized in that, The bending portion includes: a second substrate, a third wiring layer stacked on one side of the second substrate, a third adhesive layer, and a third cover film; the second substrate and the first substrate are of the same layer and material, the third wiring layer and the first wiring layer are of the same layer and material, the third adhesive layer and the first adhesive layer are of the same layer and material, and the third cover film and the first cover film are of the same layer and material.

9. The flexible circuit board as described in claim 8, characterized in that, The reinforcing structure includes: a first adhesive portion and a first covering portion stacked together; The first adhesive portion and the second adhesive layer are made of the same material and layer, and the first covering portion and the second covering film are made of the same material and layer.

10. The flexible circuit board as described in claim 8, characterized in that, The flexible circuit board further includes: a plurality of through holes located at the bending portion, the through holes penetrating the second substrate, the third wiring layer, the third adhesive layer, and the third cover film.

11. The flexible circuit board as described in claim 10, characterized in that, The third routing layer has multiple routing groups; the via is located between two adjacent routing groups.

12. The flexible circuit board as described in claim 10, characterized in that, The orthographic projection of the via onto the second substrate does not overlap with the orthographic projection of the reinforcing structure onto the second substrate.

13. The flexible circuit board as described in claim 10, characterized in that, The shape of the through hole includes: ellipse, circle, triangle, square, rectangle, trapezoid or rhombus.

14. The flexible circuit board as described in claim 13, characterized in that, The bent portion includes: a first outer boundary extending along a first direction; The through hole is elliptical in shape, and the extended line of the major axis of the ellipse intersects the first outer boundary to form a seventh angle and an eighth angle, wherein the seventh angle is smaller than the eighth angle, and the angle range of the seventh angle is 30°. o ~60 o ; Alternatively, the through hole may be rhomboid in shape, with one side of the rhombus intersecting the first outer boundary to form a ninth angle and a tenth angle, wherein the ninth angle is smaller than the tenth angle, and the angle range of the ninth angle is 30°. o ~60 o .

15. The flexible circuit board as described in claim 8, characterized in that, The third routing layer includes: at least one first routing layer; the first routing layer includes: a first routing segment, a second routing segment, and a third routing segment; The first routing segment includes: multiple first sub-routes extending along the fourth direction; the third routing segment includes: a second routing line extending along the fourth direction; the second routing segment includes: at least two connecting routing lines, one end of which is connected to the first sub-routes and the other end of which is connected to the second routing line. The connecting traces are arc-shaped.

16. The flexible circuit board as described in claim 15, characterized in that, At the connection point between the connecting trace and the first trace, the tangent of the connecting trace intersects the extension of the second trace to form an eleventh angle and a twelfth angle, wherein the eleventh angle is smaller than the twelfth angle, and the eleventh angle has an angle range of 60 degrees. o ~80 o .

17. A display device, characterized in that, include: The display module, and the flexible circuit board as described in any one of claims 8-14; The display module has a light-emitting surface and a backlight surface; The flexible circuit board further includes: a second bonding portion; the bending portion is located between the first bonding portion and the second bonding portion; the first bonding portion is bonded to the backlight surface of the display module; and the second bonding portion is bonded to the light-emitting surface of the display module.

18. The display device as claimed in claim 17, characterized in that, The bending portion further includes: a fourth wiring layer, a fourth adhesive layer, and a fourth cover film stacked on the other side of the second substrate; the fourth wiring layer is the same layer and material as the second wiring layer, the fourth adhesive layer is the same layer and material as the second adhesive layer, and the fourth cover film is the same layer and material as the second cover film. The display device further includes: a gasket; the gasket includes: a gasket body and a gasket protrusion; The display module further includes: a side surface connecting the display surface and the backlight surface; the first binding part is attached to the backlight surface of the display module through the gasket body, and the bending part is attached to the side surface of the display module through at least a portion of the outward protrusion of the gasket.

19. The display device as claimed in claim 18, characterized in that, The length of the convex portion of the gasket in the first direction is equal to the length of the flexible circuit board in the first direction; The length of the convex portion of the pad in the second direction is greater than or equal to the thickness of the display module in the direction perpendicular to the second substrate.

20. The display device as claimed in claim 18, characterized in that, The gasket is double-sided with adhesive.

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