CN109803488B - FPC capable of reducing self torsion stress - Google Patents
FPC capable of reducing self torsion stress Download PDFInfo
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- CN109803488B CN109803488B CN201910169373.4A CN201910169373A CN109803488B CN 109803488 B CN109803488 B CN 109803488B CN 201910169373 A CN201910169373 A CN 201910169373A CN 109803488 B CN109803488 B CN 109803488B
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- 238000005452 bending Methods 0.000 claims abstract description 61
- 239000000758 substrate Substances 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 abstract description 6
- 210000001503 joint Anatomy 0.000 description 6
- 238000013461 design Methods 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
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- Structure Of Printed Boards (AREA)
Abstract
The invention discloses an FPC capable of reducing self torsion stress, belonging to the technical field of circuit boards; the FPC includes a flexible substrate and a wiring layer disposed on the flexible substrate; the flexible substrate comprises a horizontal part and a vertical part, and a bending part connecting the horizontal part and the vertical part, wherein the width of the bending part is smaller than that of the horizontal part and the vertical part, so that the torsional stress acting on the end part of the flexible substrate is transferred to a narrower bending part; according to the invention, the width of the bending part of the flexible substrate is reduced, and the corner structures with different angles are arranged on the inner side and the outer side of the bending part, so that the torsional stress generated at the interface of the horizontal part and the vertical part of the flexible substrate, which are connected with the connector, is transferred to the narrower bending part, the torsional degree of the horizontal part and the vertical part is reduced, the connection area among the horizontal part, the vertical part and the connector is firmer, and the reliability of the product in the use process is increased.
Description
Technical Field
The invention belongs to the technical field of circuit boards, and particularly relates to an FPC capable of reducing self-torsion stress.
Background
The flexible circuit board (Flexible Printed Circuit Board, FPC), also called "FPC flexible board", is a printed circuit made of flexible insulating substrate, having many advantages not possessed by the rigid printed circuit board; for example, the device can be freely bent, rolled and folded, can be randomly arranged according to the space layout requirement, and can be randomly moved and contracted in the three-dimensional space, thereby achieving the integration of component assembly and wire connection. The volume of the electronic product can be greatly reduced by utilizing the FPC flexible board, and the flexible printed circuit board is suitable for the requirement of the electronic product for developing to high density, miniaturization and high reliability.
According to different requirements of a connecting structure, the FPC is designed into different shapes, wherein the L-shaped FPC is widely applied; as shown in fig. 1, the substrate and wiring layers of the conventional L-type FPC mostly adopt a right angle or 3MM rounded design at corners, and the width at the corners is the same as the width at non-corners; the two ends of the L-shaped FPC are required to be in butt joint with the connector, and the connector is inevitably subjected to machining errors/welding errors during welding, so that the interface deviates from the standard position of a design drawing, a certain amount of distortion is generated on the FPC board when the L-shaped FPC board is in butt joint with the connector, the counter force generated by the distortion not only can lead to difficult alignment of the connector, but also can lead to increased mounting difficulty, and the connector with high-density pins is easy to be misplaced and installed to lead to pin deformation of the connector; and can cause the interface to disengage from the reaction forces generated by the twisting of the flexible FPC board after a period of product use.
Disclosure of Invention
Aiming at least one defect or improvement requirement of the prior art, the invention provides the FPC capable of reducing the self torsion stress, which aims to reduce the stress of a flexible circuit board on a connector caused by processing errors, enhance the reliability of the FPC, and also reduce the size of the stress of butt joint of a printed circuit board and a flexible circuit board connector, thereby reducing the installation difficulty and solving the problems that the existing L-shaped FPC board is difficult to align and install with the connector, the stress effect generated by installation is large, and the interface is easy to disconnect after a period of use.
In order to achieve the above object, according to one aspect of the present invention, there is provided an FPC capable of reducing a self-twisting stress, comprising a flexible substrate and a wiring layer provided on the flexible substrate;
the flexible substrate comprises a horizontal part, a vertical part and a bending part connected with the horizontal part and the vertical part, wherein the width of the bending part is smaller than that of the horizontal part and the vertical part, so that torsional stress acting on the interface of the flexible substrate and the connector is transferred to the narrower bending part.
Preferably, the FPC capable of reducing the self-twisting stress has a concave first arc corner at an inner corner of the bending portion.
Preferably, the FPC capable of reducing the self-twisting stress has a concave second arc corner at the outer corner of the bending portion.
Preferably, the FPC capable of reducing the self-torsional stress has a concave second arc corner at the outer corner of the bending portion, and the angles of the first arc corner and the second arc corner are different.
Preferably, the central angle corresponding to the arc edge of the first arc corner of the FPC capable of reducing the self-torsion stress is larger than 90 degrees, and the radius length is 5+/-2 mm.
Preferably, the central angle corresponding to the arc edge of the second arc corner of the FPC capable of reducing the self-torsion stress is smaller than 90 degrees, and the radius length is 5+/-2 mm.
Preferably, the shape of the wiring layer of the FPC capable of reducing the self-twisting stress is matched with the shape of the flexible substrate, and the width of the position corresponding to the bending part of the wiring layer is smaller than the width of the other positions.
Preferably, the FPC capable of reducing the self-twisting stress has a third arc corner recessed in an inner corner of the bending portion of the wiring layer.
In general, the above technical solutions conceived by the present invention, compared with the prior art, enable the following beneficial effects to be obtained:
(1) According to the FPC capable of reducing the self-torsion stress, the width of the bending part of the flexible substrate is reduced, and the corner structures with different angles are arranged on the inner side and the outer side of the bending part, so that the torsion stress generated at the joint of the horizontal part and the vertical part of the flexible substrate and the connector is transferred to the narrower bending part, the reaction force generated after the bending part is twisted is lower, the reverse acting force on the connector can be reduced, and the connection reliability is improved; in addition, after the torsional stress is transferred to the bending part, the degree of torsion of the horizontal part and the vertical part is reduced, namely the torsion resistance of the horizontal part and the vertical part with wider width is enhanced, the connecting area between the horizontal part, the vertical part and the connector is firmer, and the reliability of the product in the use process is improved.
(2) According to the FPC capable of reducing the self-twisting stress, the width of the wiring area of the wiring layer is reduced by arranging the third arc corner, and the wiring is concentrated at the center of the bending part, so that the width of the area without the wiring of the bending part is increased; the thickness of copper in the no-wire area is reduced, so that the no-wire area is thinner and softer than the thickness of the wire area, the no-wire area is easier to twist, and the reactive force generated by the twisting part is lower; the stretching length of the wiring caused by the left-right twisting of the connector is reduced by improving the softness of the bending part, so that the reliability of the FPC is improved; in addition, the wiring layers of the horizontal part and the vertical part are uniformly wired, so that stress generated by twisting can be uniformly distributed to any area of the non-bending part, the connector can be kept flat, and the twisting degree is reduced;
(3) According to the FPC capable of reducing the self-twisting stress, the bent part of the flexible substrate adopts the rounded structure, the chamfer radius is larger than that of the conventional design, and twisting acting force applied to the bent part by the rest part of the FPC is more easily and uniformly dispersed to each position of the bent angle, so that the tearing resistance of the FPC is not reduced or even slightly improved, the use area of materials can be reduced, and the FPC is lighter.
Drawings
Fig. 1 is a schematic view of a structure of an L-shaped FPC board in the prior art;
FIG. 2 is a schematic structural diagram of a first FPC capable of reducing self-torsional stress according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a second FPC capable of reducing self-torsional stress according to an embodiment of the present invention;
Like reference numerals denote like technical features throughout the drawings, in particular: 1-a flexible substrate; 11-horizontal part; 12-vertical part; 13-a bending part; 14-a first rounded corner; 15-a first rounded corner; a 2-wiring layer; 21-third rounded corners; 3-connector.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
FIG. 2 is a schematic structural diagram of a first FPC capable of reducing self-torsional stress according to an embodiment of the present invention; as shown in fig. 2, the FPC includes a flexible substrate 1 and a wiring layer 2 provided on the flexible substrate 1; the shape of the wiring layer 2 matches the shape of the flexible substrate 1;
The flexible substrate 1 includes a horizontal portion 11, a vertical portion 12, and a bending portion 13 connecting the horizontal portion 11 and the vertical portion 12, the bending portion 13 having a width smaller than that of the horizontal portion 11, the vertical portion 12 so that a torsional stress acting at an interface of the flexible substrate 1 and the connector 3 is transferred to the narrower bending portion 13; the connector 3 comprises a male connector and a female socket, wherein an interface on the FPC is the male connector, an interface on the PCB board is the female socket, and the male connector can tightly connect the FPC with the PCB after being in butt joint with the female socket; the generation of the torsional stress is mainly due to the fact that the connector 3 is deviated from the center of an actual bonding pad due to the unavoidable alignment error of a machine in the welding process of the connector 3, the connector 3 (male) enables the FPC to generate a certain amount of torsional stress after being in butt joint with a female seat of the connector 3, and the torsional stress is mainly generated at the interface position of the horizontal part 11 or the vertical part 12 and the connector 3; in the embodiment, the width of the bending part 13 is reduced so that the bending part 13 is easier to deform relative to other positions, and therefore the torsional stress at the interface is transferred to the bending part 13; the characteristic that the bending portion 13 is more easily deformed counteracts the force generated by the FPC distortion, thereby reducing the reaction force generated by the FPC distortion and acting on the connector 3.
Specifically, the width of the bending portion 13 may be reduced by providing a concave first arc corner 14 at the inner corner of the bending portion 13, which is capable of transferring the torsional stress generated at the interface to the inner corner; secondly, a concave second arc corner 15 is arranged at the outer corner of the bending part, and the mode can transfer the torsional stress generated at the interface to the outer corner; thirdly, a first concave arc corner 14 is arranged at the inner corner of the bending part 13, a second concave arc corner 15 is arranged at the outer corner of the bending part 13, the arc directions of the second arc corner 15 and the first arc corner 14 are opposite, and the angles of central angles corresponding to the arc are unequal; the way can transfer the torsional stress generated at the interface to the inner corner and the outer corner; any of the above three ways may be used to reduce the width of the bending portion 13, thereby transferring the torsional stress generated at the interface of the flexible substrate 1 and the connector 3 to the narrower bending portion 13 and reducing the reaction force generated after the bending portion 13 is twisted; because the connector 3 may have two conditions of left deviation or right deviation in the welding process, the embodiment preferably adopts the method that the first arc corner 14 is arranged at the inner corner of the bending part 13 and the second arc corner 15 is arranged at the outer corner of the bending part, which is beneficial to uniformly dispersing the torsional stress transferred to the bending part 13 in the bending part 13 and avoiding overlarge local stress; wherein, the central angle corresponding to the arc edge of the first arc corner 14 is larger than 90 degrees, and the radius length is 5+/-2 mm, preferably 5mm; the radius length of the second arc corner 15 is 5 + -2 mm, preferably 5mm, with a central angle corresponding to the arc edge smaller than 90 deg.. The first arc corner 14 with the central angle larger than 90 degrees is arranged at the inner corner of the bending part 13, so that the torsional stress generated at the joint is dispersed, and if the central angle of the first arc corner 14 is smaller than 90 degrees, the effect of the dispersed stress is greatly reduced; the central angle corresponding to the arc edge of the second arc corner 15 is set to be smaller than 90 deg. because the space of the wiring area will be significantly reduced when the central angle corresponding to the arc edge of the second arc corner 15 is larger than 90 deg., which is disadvantageous for routing of the wiring area 2.
In the embodiment, by reducing the width of the bending part 13 of the flexible substrate 1 and arranging corner structures with different angles at the bending part 13, the torsional stress acting on the interface of the horizontal part 11 and the vertical part 12 of the flexible substrate 1 connected with the connector 3 is transferred to the narrower bending part 13, and the reactive force generated after the bending part 13 is twisted is lower, so that the reactive force on the connector 3 can be reduced, and the connection reliability is improved; in addition, after the torsional stress is transferred to the bending part 13, the degree of torsion of the horizontal part 11 and the vertical part 12 is reduced, namely the anti-torsion capacity of the horizontal part 11 and the vertical part 12 with wider width is enhanced, the connection area between the horizontal part 11, the vertical part 12 and the connector 3 is firmer, and the reliability of the product in the use process is improved.
As one preferable example of the present embodiment, the width of the position of the wiring layer 2 corresponding to the bending portion 13 is smaller than the width of other non-bending positions, as shown in fig. 3, in the present embodiment, a concave third arc corner 21 is provided at the inner corner of the bending portion of the wiring layer 2, and the width of the routing area of the wiring layer 2 is reduced by providing the third arc corner 21, so as to improve the routing density, concentrate the routing at the center of the bending portion 13, and thereby increase the width of the routing-free area of the bending portion 13 of the flexible substrate 1; the thickness of copper in the no-wire area is reduced, so that the no-wire area is thinner and softer than the thickness of the wire area, the no-wire area is easier to twist, and the reactive force generated by the twisting part is lower; the flexible degree of the bending part 13 is improved to reduce the stretching length of the wiring caused by the left-right twisting of the connector 3, so that the reliability of the FPC is improved. In addition, the wiring layers 2 of the horizontal portion 11 and the vertical portion 12 are uniformly routed, so that stress generated by twisting can be uniformly distributed to any area of the non-bending portion 13, and the connector 3 can be kept flat, and the degree of twisting can be reduced.
Stress simulation is carried out on the FPC capable of reducing the self torsion stress and the FPC is compared with a conventional L-shaped FPC, wherein the stress applied to the FPC with the right angle corner is 712Mpa under the condition that the lower end connector is welded with 0.1MM in a left-offset or right-offset mode; under the condition that the lower end connector of the FPC with the corner being a 3MM fillet is welded with 0.1MM in left offset or right offset, the stress is 610Mpa; the FPC (shown in FIG. 3) capable of reducing the self-torsion stress provided by the embodiment is stressed to 486Mpa under the condition that the lower end connector is welded with 0.1MM left or right; the experimental results show that: the stress born by the FPC is minimum and is only about 2/3 of that of the conventional design when the connector is in a skewed state, the stress of the FPC is equal no matter the connector is in a left-side deviation or a right-side deviation, the stress of the FPC is only different from the deformation direction of the FPC, and the reaction stress born by the lower-end connector obtained by the reaction force is also reduced to 486MPa, so that the FPC provided by the embodiment is easier to install after the connector is in a skewed state, and the connector is not easy to fall off after the connector is installed; in addition, when the lower connector of the FPC provided by the embodiment is welded with the left offset or the right offset 0.1MM, the reaction force born by the connector can be reduced to 60% of the original reaction force.
The FPC capable of reducing self torsion stress can be widely applied to connection between printed circuit boards, can reduce stress of the flexible circuit board to a connector caused by machining errors, and can also reduce the size of the stress of butt joint of the printed circuit board and the flexible circuit board connector, so that the mounting difficulty is reduced, and the service life of the FPC and the connector is prolonged.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (5)
1. An FPC capable of reducing self-twisting stress is characterized by comprising a flexible substrate and a wiring layer arranged on the flexible substrate;
The flexible substrate comprises a horizontal part and a vertical part, and a bending part connecting the horizontal part and the vertical part, wherein the width of the bending part is smaller than that of the horizontal part and the vertical part, so that the torsional stress acting on the end part of the flexible substrate is transferred to a narrower bending part;
the inner corner of the bending part is provided with a first concave arc corner, and the outer corner of the bending part is provided with a second concave arc corner;
The central angle corresponding to the arc edge of the first arc corner is larger than 90 degrees, and the central angle corresponding to the arc edge of the second arc corner is smaller than 90 degrees.
2. The FPC for reducing self-torsional stress according to claim 1, wherein the radius length of the first circular arc corner is 5±2mm.
3. The FPC for reducing self-torsional stress according to claim 1, wherein the radius length of the second circular arc corner is 5±2mm.
4. The FPC of claim 1 wherein said wiring layer has a shape matching the shape of the flexible substrate and the width of the bent portion of the wiring layer is smaller than the width of the other non-bent region.
5. The FPC capable of reducing self-torsional stress according to claim 4, wherein the inner corner of the wiring layer has a recessed third rounded corner.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910169373.4A CN109803488B (en) | 2019-03-06 | 2019-03-06 | FPC capable of reducing self torsion stress |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910169373.4A CN109803488B (en) | 2019-03-06 | 2019-03-06 | FPC capable of reducing self torsion stress |
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| Publication Number | Publication Date |
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| CN109803488A CN109803488A (en) | 2019-05-24 |
| CN109803488B true CN109803488B (en) | 2024-05-17 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201910169373.4A Active CN109803488B (en) | 2019-03-06 | 2019-03-06 | FPC capable of reducing self torsion stress |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1956619A (en) * | 2005-10-26 | 2007-05-02 | 恩益禧电子股份有限公司 | Flexible board |
| CN207678070U (en) * | 2018-01-19 | 2018-07-31 | 昆山国显光电有限公司 | FPC golden fingers, flexible PCB and flexible display screen |
| CN209949531U (en) * | 2019-03-06 | 2020-01-14 | 武汉精立电子技术有限公司 | FPC capable of reducing self-torsion stress |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100733877B1 (en) * | 2000-07-06 | 2007-07-02 | 엘지.필립스 엘시디 주식회사 | Flexable Printed Circuit Film |
-
2019
- 2019-03-06 CN CN201910169373.4A patent/CN109803488B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1956619A (en) * | 2005-10-26 | 2007-05-02 | 恩益禧电子股份有限公司 | Flexible board |
| CN207678070U (en) * | 2018-01-19 | 2018-07-31 | 昆山国显光电有限公司 | FPC golden fingers, flexible PCB and flexible display screen |
| CN209949531U (en) * | 2019-03-06 | 2020-01-14 | 武汉精立电子技术有限公司 | FPC capable of reducing self-torsion stress |
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| CN109803488A (en) | 2019-05-24 |
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