TWI687137B - Soft circuit board with a reduced rebounding force - Google Patents

Abstract

A soft circuit board with a reduced rebounding force is disclosed to solve the problem where the conventional soft circuit board tends to cause the defective electrical property due to the rebounding force resulting from bending of the circuit board. The soft circuit board includes an insulating layer, a conductive layer and at least one guiding hole. The insulating layer includes a folding line and a bending area on both sides of the folding line. The conductive layer covers the insulating layer. The at least one guiding hole is arranged on the bending area along the folding line and along a line parallel to the folding line. The insulating layer and the conductive layer are bent along the at least one guiding hole. The guiding hole do not extend to the conductive layer.

Description

Flexible circuit board with reduced bending rebound force

The invention relates to a flexible circuit board with reduced bending resilience, especially a flexible circuit board with reduced bending resilience that can be easily bent and elastically arranged in various display modules.

General electronic products integrate several electronic components through a printed circuit board (PCB) to form a complete circuit structure, so that all electronic components can function and work together to achieve product efficiency. Nowadays, the development of electronic products tends to be lighter, thinner, shorter, and with higher performance. Therefore, in addition to the miniaturization of electronic components and the improvement of specifications, flexible circuit boards with light weight, thin thickness, high wiring density, and flexible shapes can also be used. (Flexible Printed Circuit, FPC) or a flexible circuit board (Chip on Film, COF) using die-on-chip bonding. In this way, the circuit board can be equipped with complex circuits to integrate more electronic components in a smaller area, making it thin and flexible The flexible circuit board is flexibly arranged in an assembly structure with a small space, or used in products such as wearables and mobile phone displays.

Various applications of conventional flexible circuit boards have the risk of causing electrical defects. For example, in the process of assembling an electronic product, the conventional flexible circuit board must be folded in half and divided into an upper half and a lower half, so that the upper half The lower half and the lower half are combined with different circuit modules, wherein the distance between the upper half and the lower half is reduced to achieve the purpose of thinning the product, which will lead to the connection of the upper half and the lower half One of the bending parts bears a stress that is greater than the joint of the flexible circuit board The adhesion of Anisotropic Conductive Film (ACF) makes the assembled electronic products have defective patterns such as line peeling, short circuit, open circuit, high impedance and other electrical defects; otherwise, relax the upper half and the The spacing between the lower halves to reduce the stress on the bending part will cause the flexible circuit board to occupy the assembly space and affect the flexibility of the application.

In view of this, the conventional flexible circuit boards still need to be improved.

In order to solve the above problems, an object of the present invention is to provide a flexible circuit board with reduced bending resilience, which reduces the recovery resilience during bending, and can be easily bent and installed in an electronic product with a narrow space.

The next object of the present invention is to provide a flexible circuit board with reduced bending resilience, to avoid circuit peeling, twisting or breaking of its electronic circuit, and to reduce the possibility of defective electrical defects.

The following directivity or similar terms of the present invention, such as "upper (top)", "lower (bottom)", "inner", "outer", "side", etc., mainly refer to the directions of the attached drawings, each Directionality or its approximate terms are only used to help explain and understand the embodiments of the present invention, and are not intended to limit the present invention.

The flexible circuit board with reduced bending resilience of the present invention includes: an insulating layer having a fold line and a bending area on both sides of the fold line; a conductive layer covering the insulating layer ; And at least one guide hole, the at least one guide hole is arranged in the bending region along the fold line and the parallel line of the fold line, the insulating layer and the conductive layer are bent along the at least one guide hole, the at least one guide The hole does not extend to the conductive layer.

According to this, the flexible circuit board with reduced bending rebound force of the present invention effectively reduces the rebound force generated by bending the insulating layer and the internal stress of the bending part by the at least one guide hole provided along the folding line, so that The flexible circuit board can be flexibly installed in electronic products with a small space, and can prevent the electronic circuit on the conductive layer from being twisted, broken or peeled by internal stress, which has Make sure that the module connected to the flexible circuit board is functioning properly and can make the product thin.

Wherein, the number of the guide holes is several, the plurality of guide holes are arranged at equal intervals with a wide pitch, the diameter width of each guide hole parallel to the fold line is a short axis, and the diameter width perpendicular to the fold line is a long axis . In this way, the even distribution of the several via holes has the effect of dispersing the stress evenly.

Wherein, the wide distance is greater than the short axis, the short axis is 0.4 mm to 2 mm, and the long axis is 0.4 mm to 3 mm. In this way, the dispersion of the several via holes has the effect of maintaining the structural strength of the insulating layer.

Wherein, the wide distance is 0.2 mm to 1 mm, the short axis is 0.2 mm to 2 mm, and the wide distance is smaller than the short axis, and the long axis is 0.4 mm to 3 mm. In this way, the dense arrangement of the several via holes has the effect of greatly reducing the internal stress.

Wherein, the shape of each guide hole is based on the broken line as the axis of symmetry. In this way, the center of each of the guide holes can correspond to the part with the highest degree of curvature, which has the maximum effect of dispersing the stress correctly.

Wherein, the shape of each of the guide holes is circular, oval, rectangular or hexagonal. In this way, each of the guide holes can be adjusted according to the actual situation of the installation structure, which has the effect of being applied to different structures.

Wherein, each of the guide holes is composed of a plurality of channels arranged in parallel to form the shape of the guide holes. In this way, the total area of the via hole can be reduced, which has the effect of maintaining the structural strength of the insulating layer.

Wherein, the number of the guide holes is two, the two guide holes present two straight lines parallel to the broken line, wherein one of the two guide holes has a line width of 0.02 mm to 1 mm, and a guide between the two guide holes The hole spacing is 0.2 mm to 1 mm. In this way, the stress distribution through the two straight guide holes can be used for the two bending points and has the effect of being applied to different structures.

Wherein, the distance between the guide holes is based on the broken line as a perpendicular line. In this way, it has the effect of evenly distributing stress.

The number of the guide holes is three, the three guide holes are three straight lines parallel to the fold line, and the three lines of the three guide holes are 0.02 mm to 1 mm wide. In this way, through three bending points Stress distribution has the effect of being applied to different structures.

Wherein, the guide hole in the middle uses the broken line as the axis of symmetry. In this way, it has the effect of evenly distributing stress.

Wherein, the number of the guide holes is several, the plurality of guide holes are straight lines parallel to the fold line, the plurality of guide holes are arranged at equal intervals, and the line width of one of the guide holes is 0.02 mm to 0.05 mm. In this way, stress can be dispersed through several bending points, which has the effect of evenly dispersing stress.

Wherein, the plurality of guide holes present several line segments parallel to the polyline and form at least two straight lines, the side length of each of the guide holes parallel to the polyline is one line segment length, and the plurality of guide holes on the same straight line have a gap, etc. Spacing. In this way, the total area of the via hole can be reduced, which has the effect of maintaining the structural strength of the insulating layer.

Among them, the length of the line is from 1 mm to 10 mm, and the gap is from 0.2 mm to 1 mm. In this way, the even distribution of the several via holes has the effect of dispersing the stress evenly.

Wherein, the number of the guide hole is a single one, the guide hole is a continuous S-shape and a rectangular curve coiled along the fold line, and several line segments of the guide hole perpendicular to the fold line are a slit. In this way, the shape of the guide holes is evenly distributed, which has the effect of dispersing the stress evenly.

The length of the slit is 0.4 mm to 3 mm, and the width of one of the guide holes is 0.02 mm to 0.05 mm. In this way, the dense arrangement of the slits has the effect of greatly reducing internal stress.

Wherein, the slit uses the broken line as a perpendicular line. In this way, the center of the guide hole can correspond to the part with the highest degree of curvature, which has the maximum effect of dispersing the stress correctly.

Wherein, the at least one via hole penetrates through the upper and lower sides of the insulating layer. In this way, the total volume of the insulating layer at the bending portion can be reduced, which has the effect of greatly reducing the internal stress.

Wherein, the at least one via hole only passes through the insulating layer without attaching one of the conductive layers A blind hole on the side that does not penetrate the insulating layer. In this way, it has the effect of maintaining the structural strength of the insulating layer and avoiding damage to the conductive layer.

1: Insulation

2: conductive layer

3: pilot hole

31: Wide pitch

32: short axis

33: Long axis

34: line width

35: Guide hole spacing

36: line length

37: clearance

38: slit

L: Polyline

F: Anisotropic conductive adhesive

M1: LCD display module

M2: microchip

M3: circuit board

P: protective layer

Figure 1: A perspective view of the first embodiment of the present invention.

Fig. 2: Front view of the first embodiment of the present invention.

Figure 3: Sectional view along line A-A of Figure 2.

Figure 4: The state diagram of the pilot hole as shown in Figure 3.

Figure 5: The state diagram of the pilot hole as shown in Figure 3.

Figure 6: Assembly structure diagram of the present invention.

Figure 7: Front view of a second embodiment of the invention.

Figure 8: Front view of a third embodiment of the invention.

Figure 9: Front view of a fourth embodiment of the invention.

Figure 10: Front view of a fifth embodiment of the invention.

Figure 11: Front view of a sixth embodiment of the invention.

Figure 12: Front view of a seventh embodiment of the invention.

Figure 13: Front view of an eighth embodiment of the invention.

Figure 14: A bar graph of the experimental data of the rebound force of eight embodiments of the present invention.

In order to make the above and other objects, features and advantages of the present invention more obvious and understandable, the preferred embodiments of the present invention are described below in conjunction with the attached drawings, which are described in detail as follows: Please refer to FIG. 1, It is the first embodiment of the flexible circuit board with reduced bending resilience according to the present invention, which includes an insulating layer 1, a conductive layer 2 and at least one via 3, the conductive layer 2 covering the insulating layer 1, the At least one via hole 3 is arranged on the insulating layer 1 along a fold line L.

During the assembly process, the insulating layer 1 is bent along the folding line L or one of the bending regions on both sides of the folding line L. Therefore, the insulating layer 1 preferably has high ductility and tensile strength. The insulating layer 1 may be polyimide, which has the characteristics of wide application temperature and resistance to chemical corrosion, while effectively isolating the interference of electrical circuits.

The conductive layer 2 is attached to the insulating layer 1 and processed into an electronic circuit with high conductivity. Furthermore, the conductive layer 2 preferably has high ductility so that the conductive layer 2 can be bent with the insulating layer 1. The conductive layer 2 may be a metal coating, and the common metal material is copper or tin.

Please refer to FIGS. 2 to 5, the at least one via hole 3 is drilled in the insulating layer 1, but does not extend to the conductive layer 2. As shown in FIG. 3, the via hole may pass through the insulating layer 1 Through holes (TH) on the upper and lower sides, as shown in FIG. 4, the via holes may also pass through only one side of the insulating layer 1 that is not attached to the conductive layer 2 and does not penetrate the insulating layer 1 Blind via hole (BVH), as shown in Figure 5, the guide hole may also be several parallel arranged channels, and the several channels may be through holes or blind holes.

Please refer to FIG. 2, in the first embodiment, the at least one guide hole 3 has an elliptical shape and is arranged at equal intervals with a wide pitch 31. The shape of each guide hole 3 is based on the broken line L as the axis of symmetry. The diameter width of each guide hole 3 parallel to the fold line L is a short axis 32 and the diameter width perpendicular to the fold line L is a long axis 33, wherein the short axis 32 is preferably 0.4 mm to 2 mm and is implemented in the first embodiment In the example, it is 0.55 mm, and the long axis 33 is preferably 0.4 mm to 3 mm. In the first embodiment, it is 1.5 mm, and the width 31 is larger than the short axis 32.

Referring to FIG. 6, according to the foregoing structure, the insulating layer 1 and the conductive layer 2 are bent with the conductive layer 2 as the inner side, so that the conductive layer 2 is respectively made of anisotropic conductive adhesive F or welding Modules that are electrically connected to different functions. The module may be a liquid crystal display module M1, a microchip M2, or another circuit board M3. In addition, the electrically unconnected portion between the conductive layer 2 and each module may have A protective layer P, which is an insulating material that can prevent the conductive layer 2 from short-circuiting with each module, and the insulating layer 1 and the conductive layer 2 are bent along the at least one guide hole 3, Since each of the via holes 3 has a relatively thin thickness, the internal stress of the insulating layer 1 and the conductive layer 2 during the bending process can be effectively reduced, and the circuit of the conductive layer 2 can be prevented from being broken or broken due to the bending internal stress Peel off.

Please refer to FIG. 7, which is the second embodiment of the flexible circuit board with reduced bending resilience of the present invention. Compared with the first embodiment, the main difference is that in the second embodiment, each The guide holes 3 have a rectangular shape, but each of the guide holes 3 may also have a circular or hexagonal shape, but not limited to this. The width 31 of each guide hole is smaller than the short axis 32, wherein the width 31 is preferably 0.2 mm to 1 mm and 0.3 mm in the second embodiment, and the short shaft 32 is preferably 0.2 mm to 2 mm and 0.4 mm in the second embodiment.

Please refer to FIG. 8, which is the third embodiment of the flexible circuit board with reduced bending resilience according to the present invention. Compared with the first embodiment, the main difference is that in the third embodiment, the guide hole The number of two is two, the two guide holes 3 present two straight lines parallel to the fold line L, wherein the line width 34 of one of the two guide holes 3 is preferably 0.02 mm to 1 mm and 0.4 mm in the third embodiment , And a guide hole spacing 35 between the two guide holes 3 is preferably 0.2 mm to 1 mm and is 1 mm in the third embodiment, and the fold line L is preferably a vertical line in the guide hole spacing 35.

Please refer to FIG. 9, which is the fourth embodiment of the flexible circuit board with reduced bending resilience according to the present invention. Compared with the third embodiment, the main difference is that in the fourth embodiment, the guide hole The number of the three guide holes 3 is three straight lines parallel to the fold line L. The line width 34 of the three guide holes 3 is preferably 0.02 mm to 1 mm and in the fourth embodiment is 0.3 Mm, 0.2 mm and 0.3 mm, and the fold line L is preferably the axis of symmetry of the guide hole 3 in the middle.

Please refer to FIG. 10, which is the fifth embodiment of the flexible circuit board with reduced bending resilience of the present invention. Compared with the fourth embodiment, the main difference is that in the fifth embodiment, the at least one The guide holes 3 present several line segments parallel to the fold line L and form three straight lines, the length of the side of each guide hole 3 parallel to the fold line L is a line segment length 36, and the at least one guide hole 3 on the same line has a gap 37 are arranged at equal intervals, wherein the length of the line segment 36 is preferably 1 mm to 10 mm and In the fifth embodiment, it is 3 mm and the gap 37 is preferably 0.2 mm to 1 mm, and in the fifth embodiment, it is 0.3 mm.

Please refer to FIG. 11, which is the sixth embodiment of the flexible circuit board with reduced bending resilience according to the present invention. Compared with the third embodiment, the main difference is that in the sixth embodiment, the guide hole The number of the two is two, the two guide holes 3 present two straight lines parallel to the fold line L, wherein the line width 34 of one of the two guide holes 3 is preferably 0.02 mm to 1 mm and is 0.1 mm in the sixth embodiment Or 0.05 mm.

Please refer to FIG. 12, which is the seventh embodiment of the flexible circuit board with reduced bending resilience of the present invention. Compared with the sixth embodiment, the main difference is that in the seventh embodiment, the at least one The guide holes 3 are straight lines parallel to the fold line L, and the at least one guide holes 3 are arranged at equal intervals.

Please refer to FIG. 13, which is the eighth embodiment of the flexible circuit board with reduced bending resilience according to the present invention. The main difference from the first embodiment is that in the eighth embodiment, the guide hole 3 is A rectangular curve that exhibits a continuous S shape and is coiled along the fold line L, and several segments of the guide hole 3 perpendicular to the fold line L are a slit 38, wherein the slit length of the slit 38 is preferably 0.4 mm to 3 mm In the eighth embodiment, it is 1.5 mm and the line width 34 of the guide hole 3 is preferably 0.02 mm to 0.05 mm, and in the eighth embodiment, it is 0.02 mm, and the fold line L is preferably the slit 38 Vertical line.

Please refer to FIG. 14, which is the rebound test result of the flexible circuit board of the present invention with reduced bending rebound force, which is bent at the same angle and position. The above eight embodiments have the same material, thickness and drilling depth Samples, then measure the recovery rebound force of each sample at this time and draw as a bar graph. Data a and data b represent the rebound test data of the third and fourth embodiments of the present invention, respectively, having a relatively lowest rebound force of less than 0.4 g; data c represents the second embodiment, and data d represents the fifth embodiment And data e represent the seventh embodiment, wherein the test rebound force is greater than 0.4 g and less than 0.5 g; data f represents the eighth embodiment, and data g represents The first embodiment and the data h represent the sixth embodiment, in which the test rebound force is greater than 0.5 g and less than 0.6 g. Therefore, the different types of the guide holes 3 of the embodiments of the present invention lead to different test rebound forces, which can be applied to different bending methods, and the flexible circuit board of the present invention with reduced bending rebound force can be based on actual The shape of the guide hole 3 is selected according to the curved shape of the assembly, and is not limited to the foregoing eight embodiments.

In summary, the flexible circuit board with reduced bending rebound force of the present invention effectively reduces the rebound force generated by bending the insulating layer and the internal stress of the bending part by the at least one guide hole arranged along the bending part The flexible circuit board can be flexibly installed in electronic products with small space, and the electronic circuit on the conductive layer can be prevented from being twisted, broken or peeled by internal stress, ensuring the normal operation of the module connected to the flexible circuit board. And can make the product thin.

Although the present invention has been disclosed using the above-mentioned preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with this art without departing from the spirit and scope of the present invention still makes various changes and modifications to the above-mentioned embodiments. The technical scope of the invention is protected, so the scope of protection of the present invention shall be subject to the scope defined in the appended patent application.

1: Insulation

2: conductive layer

3: pilot hole

L: Polyline

Claims (19)

A flexible circuit board with reduced bending resilience includes: an insulating layer having a fold line and a bending area on both sides of the fold line; a conductive layer covering the insulating layer; and At least one via hole, the at least one via hole is arranged in the bending region along the fold line and the parallel line of the fold line, the insulating layer and the conductive layer are bent along the at least one via hole, the at least one via hole is not Extend to the conductive layer. The flexible circuit board with reduced bending resilience as described in item 1 of the patent application scope, wherein the number of the guide holes is several, the plurality of guide holes are arranged at a wide pitch at equal intervals, and each of the guide holes is parallel The diameter width of the fold line is a short axis, and the diameter width of the fold line is a long axis. The flexible circuit board with reduced bending resilience as described in item 2 of the patent application scope, wherein the width is greater than the short axis, the short axis is 0.4 mm to 2 mm, and the long axis is 0.4 mm to 3 mm . The flexible circuit board with reduced bending resilience as described in item 2 of the patent application scope, wherein the wide distance is 0.2 mm to 1 mm, the short axis is 0.2 mm to 2 mm, and the wide distance is less than the short Axis, the long axis is 0.4 mm to 3 mm. The flexible circuit board with reduced bending rebound force as described in Item 2 of the patent application scope, wherein the shape of each of the guide holes is based on the fold line as the axis of symmetry. The flexible circuit board with reduced bending resilience as described in item 5 of the patent application scope, wherein the shape of each of the guide holes is circular, oval, rectangular or hexagonal. The flexible circuit board with reduced bending resilience as described in item 6 of the patent application scope, wherein each of the guide holes is composed of several parallelly arranged channels to form the shape of the guide holes. The flexible circuit board with reduced bending rebound force as described in item 1 of the patent application scope, wherein the number of the guide holes is two, and the two guide holes present two straight lines parallel to the fold line, wherein the two guides The line width of one of the holes is 0.02 mm to 1 mm, and the distance between one guide hole between the two guide holes is 0.2mm~1mm. The flexible circuit board with reduced bending resilience as described in item 8 of the patent application scope, wherein the distance between the guide holes is based on the fold line as a perpendicular line. The flexible circuit board with reduced bending resilience as described in item 1 of the patent application scope, wherein the number of the guide holes is three, and the three guide holes present three straight lines parallel to the fold line. The width of the three lines is 0.02 mm to 1 mm. The flexible circuit board with reduced bending rebound force as described in item 10 of the patent application scope, wherein the guide hole located in the middle uses the fold line as an axis of symmetry. The flexible circuit board with reduced bending resilience as described in item 1 of the patent application scope, wherein the number of the guide holes is several, and the plurality of guide holes are a plurality of straight lines parallel to the fold line, and the plurality of guides The holes are arranged at equal intervals, and one of the guide holes has a line width of 0.02 mm to 0.05 mm. The flexible circuit board with reduced bending resilience as described in item 12 of the patent application scope, wherein the plurality of guide holes present several line segments parallel to the fold line and form at least two straight lines, and each of the guide holes is parallel to the fold line The length of one side is the length of a line segment, and the several guide holes on the same straight line are arranged with a gap at equal intervals. The flexible circuit board with reduced bending rebound force as described in item 13 of the patent application scope, wherein the length of the line segment is 1 mm to 10 mm, and the gap is 0.2 mm to 1 mm. The flexible circuit board with reduced bending rebound force as described in item 1 of the patent application scope, wherein the number of the guide hole is a single one, the guide hole is a continuous S-shaped and a rectangular curve coiled along the fold line, Several line segments of the guide hole perpendicular to the fold line form a slit. The flexible circuit board with reduced bending resilience as described in item 15 of the patent application scope, wherein the slit length of the slit is 0.4 mm to 3 mm, and the line width of one of the guide holes is 0.02 mm to 0.05 mm. The flexible circuit board with reduced bending resilience as described in item 15 of the patent application scope, wherein the slit uses the fold line as a perpendicular line. According to the flexible circuit board with reduced bending resilience as described in any one of claims 1 to 17, the at least one via hole passes through the upper and lower sides of the insulating layer. According to the flexible circuit board with reduced bending resilience as described in any one of claims 1 to 17, the at least one via hole only passes through one side of the insulating layer not attached to the conductive layer and does not penetrate the Blind hole in the insulating layer.

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