CN212061907U

CN212061907U - Conductive layer stack and foldable electronic device

Info

Publication number: CN212061907U
Application number: CN202021145402.8U
Authority: CN
Inventors: 蔡宜珍; 方玮嘉; 朱俊鸿; 萧仲钦
Original assignee: Cambrios Film Solutions Xiamen Corp
Current assignee: Cambrios Film Solutions Xiamen Corp
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2020-12-01
Anticipated expiration: 2030-06-19

Abstract

A conductive layer stack and a foldable electronic device, the conductive layer stack including a conductive layer and a thickening layer, the conductive layer extending in a first direction. The thickening layer is located above or below the conductive layer. The conductive layer stack can withstand breaking after folding more than 40000 times when bent at a radius of curvature R of 3 mm and bent 180 ° perpendicularly or parallel to the first direction.

Description

Conductive layer stack and foldable electronic device

Technical Field

The present disclosure relates to a conductive stack, and more particularly, to a conductive stack for use in traces of a foldable electronic device.

Background

Electronic devices are becoming smaller and faster, and among them, flexible electronic technologies that can maintain high performance and provide flexibility to electronic devices are the most spotlighted new technologies in the next generation, including flexible panels, displays, batteries, wearable electronic devices, etc.

However, in the foldable electronic device, the traces at the bent portion may be easily broken through multiple bending, thereby affecting the transmission of signals and the performance of the foldable electronic device.

SUMMERY OF THE UTILITY MODEL

In view of the above, it is an object of the present disclosure to provide a conductive stack having a thickened layer to improve the bending resistance of a foldable electronic device.

Some embodiments of the present disclosure provide a conductive layer stack comprising a conductive layer and a thickening layer. The conductive layer extends in a first direction. The thickening layer is positioned above or below the conductive layer, and the conductive layer stack can bear the folding times of more than 40000 times without breaking when the conductive layer stack is bent by 180 degrees along the extending direction vertical to or parallel to the first direction, wherein the curvature radius R is 3 mm.

In some embodiments, the length of the thickening layer in the first direction is greater than 9 millimeters and does not exceed the length of the conductive layer extending in the first direction.

In some embodiments, the length of the thickening layer in the first direction is greater than 15 millimeters and does not exceed the length of the conductive layer extending in the first direction.

In some embodiments, the included angle between the bending axis of the conductive layer stack and the two ends of the thickening layer is 180 ° to 360 °.

In some embodiments, the thickening layer increases the amount of stress strain when the conductive stack is bent by 0.1 to 10%, and the radius of curvature of the conductive stack is reduced by 0.5 to 3 millimeters.

In some embodiments, the thickening layer is located on the stress-tensile side of the conductive stack when it is bent.

In some embodiments, a foldable electronic device is proposed, which comprises the conductive layer stack described in the above and below embodiments or examples.

Some embodiments of the present disclosure provide a foldable electronic device including a display area and a non-display area. The non-display area is located outside the display area, wherein the non-display area has a plurality of wires extending along a first direction, and each wire of the plurality of wires includes: a substrate and a conductive layer over the substrate. The non-display area has a local thickened area including a bending part of the foldable electronic device, and each of the plurality of wirings in the local thickened area further includes a thickened layer above or below the conductive layer and located on a stress stretching side of the foldable electronic device when the foldable electronic device is bent.

In some embodiments, in the foldable electronic device, the width of the local thickened region extends along a second direction perpendicular to the first direction, and one of the traces has a width W₁The distance between the tracks is P₁The number of the routing lines is N, and the width range of the local thickening region is between W₁To (W)₁+P₁) x N, respectively.

In some embodiments, in the folded electronic device, a length of the thickening layer along the first direction is greater than 3 millimeters.

In some embodiments, in the foldable electronic device, the thickening layer is formed of a metal material, and a ratio of the thickness of the thickening layer to the thickness of the conductive layer is about 0.05-5.

In some embodiments, in the foldable electronic device, the thickening layer is formed of a non-metallic material or a composite conductive material, and a ratio of the thickness of the thickening layer to the thickness of the conductive layer is about 0.1-50.

In some embodiments, in the folding electronic device, the thickening layer is formed of a metal material, and a value of a thickness of the substrate multiplied by a Young's modulus of the substrate is about 100 to 300, a value of a thickness of the conductive layer multiplied by a Young's modulus of the conductive layer is about 20 to 70, and a value of a thickness of the thickening multiplied by a Young's modulus is about 5 to 30.

In some embodiments, in the foldable electronic device, the thickening layer is formed of a non-metallic material or a composite conductive material, and a value of a thickness of the substrate multiplied by a young's modulus of the substrate is about 100 to 300, a value of a thickness of the conductive layer multiplied by a young's modulus of the conductive layer is about 20 to 70, and a value of a thickness of the thickening layer multiplied by a young's modulus of the thickening layer is about 2 to 60.

In some embodiments, in a folded electronic device, the thickening layer comprises: a first polymer layer and a second polymer layer. The second polymer layer is over the first polymer layer, wherein the material of the first polymer layer is different from the material of the second polymer layer.

In some embodiments, in the folded electronic device, a ratio of the young's modulus of the first polymer layer to the young's modulus of the second polymer layer is about 10³～10⁶。

In some embodiments, in the foldable electronic device, a ratio of a thickness of the first polymer to a thickness of the conductive layer is about 30 to 100, a ratio of a thickness of the second polymer to a thickness of the conductive layer is about 30 to 100, and a ratio of a thickness of the first polymer to a thickness of the second polymer is about 0.5 to 2.

Drawings

The present disclosure is best understood from the following detailed description when read with the accompanying drawing figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale and are used for illustrative purposes only. In fact, various features may be arbitrarily increased or decreased for clarity of discussion.

FIG. 1A is a schematic view of a panel according to some embodiments of the present disclosure;

fig. 1B-1D are partial cross-sectional views of traces according to some embodiments of the present disclosure;

FIG. 1E is an enlarged partial view of region 114 of the panel of FIG. 1A;

fig. 2A and 2B are schematic views of a conductive layer stack in a bent state;

FIGS. 3A and 3B are schematic diagrams of a conductive layer stack of a comparative example in a bent state and an unbent state;

fig. 4A to 4C are respectively a conductive layer stack according to some experimental examples;

fig. 5A-5D are schematic configuration diagrams of a conductive layer stack according to some embodiments;

fig. 6A and 6B are schematic diagrams of a conductive layer stack according to some embodiments in a folded state and in an unfolded state;

fig. 6C and 6D are schematic diagrams of a conductive layer stack according to some embodiments in a folded state and in an unfolded state;

fig. 6E and 6F are schematic diagrams of a conductive layer stack according to some embodiments in a folded state and in an unfolded state;

fig. 7A and 7B are schematic diagrams of a conductive layer stack according to some embodiments in a folded state and in an unfolded state;

fig. 7C and 7D are schematic diagrams of a conductive layer stack according to some embodiments in a folded state and in an unfolded state;

fig. 7E and 7F are schematic diagrams of a conductive layer stack according to some embodiments in a folded state and in an unfolded state;

FIGS. 8A-8I are cross-sectional views of a folded electronic device at various intermediate stages in the manufacturing process, according to some embodiments of the present disclosure;

FIGS. 9A-9J are cross-sectional views of a folded electronic device at various intermediate stages in the manufacturing process, according to some embodiments of the present disclosure;

FIGS. 10A-10G are cross-sectional views of a folded electronic device at various intermediate stages in the manufacturing process, according to some embodiments of the present disclosure;

FIGS. 11A-11H are cross-sectional views of a folded electronic device at various intermediate stages in the manufacturing process, according to some embodiments of the present disclosure;

fig. 12A-12H are cross-sectional views of a folded electronic device at various intermediate stages in the manufacturing process, according to some embodiments of the present disclosure.

[ notation ] to show

20 stack of conductive layers

22: substrate

24 layer of wire-passing material

26 thickening layer

30 stack of conductive layers

32: substrate

34 routing material layer

36 thickening layer

40 stack of conductive layers

42 base plate

44 metal layer

50 stack of conductive layers

52 substrate

54 conductive layer

56 metal layer

58 thickening layer

60 conductive layer stack

62 base plate

64 conductive layer

66 metal layer

68 thickening layer

70 conductive layer Stack

72 base plate

74 conductive layer

76 metal layer

78 first polymer layer

80 second Polymer layer

100: panel

110 routing

112. 114, 116 area

120 stack of conductive layers

122 base plate

124 metal layer

126 thickening layer

128 conductive layer

130 stack of conductive layers

132 substrate

134 conductive layer

136 metal layer

138 thickening layer

140 stack of conductive layers

142 base plate

144 metal layer

146 conductive layer

148 thickening layer

210 conductive layer Stack

212 substrate

214 routing material layer

216 thickening layer

220 stack of conductive layers

222 substrate

224 routing material layer

226 first Polymer layer

228 second Polymer layer

230 conductive layer stack

232 base plate

234 catalyst layer

236 conducting layer

238 thickening layer

240 conductive layer stack

242 base plate

244 catalyst layer

246 conductive layer

248 first Polymer layer

250 second polymer layer

310 stack of conductive layers

312 substrate

314 metal layer

316 thickening layer

318 conductive layer

330 stack of conductive layers

332 base plate

334 metal layer

336 conductive layer

338 thickening layer

350 stack of conductive layers

352 substrate

354 conductive layer

356 metal layer

358 thickening layer

410 conductive layer stack

412 conductive layer

414 structural layer with double-sided metal film

414A metal layer

414B substrate

414C metal layer

416 thickening layer

418 conductive layer

430 conductive layer stack

432 conductive layer

434 structural layer with double-sided metal film

434A metal layer

434B substrate

434C metal layer

436 conducting layer

438 thickening layer

450: conductive layer stack

452 metal layer

454 structural layer with double-sided conductive film

454A conductive layer

454B substrate

454C conductive layer

456 metal layer

458 thickening layer

502 base plate

504 metal layer

506 photoresist layer

508 thickening layer

510 photoresist layer

512 conductive layer

514 photoresist layer

516 protective layer

522 base plate

524 metal layer

526 photoresist layer

528 conductive layer

530 photoresist layer

532 thickening layer

534 photoresist layer

536 protective layer

602 substrate

604 conducting layer

606 Metal layer

608 photoresist layer

610 thickening layer

612 photoresist layer

614 protective layer

702 base plate

704 metal layer

706 photoresist layer

708 conductive layer

710 photoresist layer

712 protective layer

714, thickening layer

722 base plate

724 conductive layer

726 metal layer

728 photoresist layer

730 first Polymer layer

732 second Polymer layer

AA. BB, CC line

R₁、R₂Radius of curvature

W₁、W₂Length of

θ₁、θ₂Angle of rotation

Detailed Description

The present disclosure provides many different implementations or embodiments for implementing different features of the disclosure. Specific embodiments of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, in the description that follows, a second feature may be formed over or on a first feature, and may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact.

Spatially relative terms, such as "below," "lower," "above," "upper," and the like, may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device or apparatus in use or operation in addition to the orientation depicted in the figures. Other orientations of a device or apparatus are possible (rotated 90 degrees or at other orientations) and the spatially relative terms used herein may be interpreted accordingly.

In a display device, a metal oxide such as Indium Tin Oxide (ITO) is commonly used as a material for stacking conductive layers to form a trace. However, since a metal oxide material such as indium tin oxide is brittle and has poor flexibility, the conductive layer stack formed is easily broken. In addition, in the stacked conductive layers using nano-silver as the conductive layer, since the bending region of the display device still contains other metal wires besides the nano-silver wires, the stress value that the metal material itself can bear is relatively small, and deformation is easily generated to increase the resistance value.

The wiring design of the folding electronic device has two key points: firstly, because the bent part must bear tens of thousands of folds, the bent part needs to have certain structural strength; second, the trace of the foldable electronic device needs to have better foldability, i.e. have smaller curvature radius of bending.

Some embodiments of the present disclosure provide a conductive layer stack that adds a thickening layer on the tensile side of the bend that is subjected to the greatest stress, thereby achieving improved folding characteristics at smaller radii of curvature.

In some embodiments, the conductive layer stack may be formed as a trace of an electronic device, and is applied to a foldable electronic device, for example, an electronic device having a panel, such as a mobile phone, a tablet, a wearable electronic device (e.g., a smart band, a smart watch, a virtual reality device, etc.), a television, a display, a notebook, an electronic book, a digital photo frame, a navigator, or the like.

Fig. 1A illustrates a schematic diagram of a panel, according to some embodiments of the present disclosure. The panel 100 is a foldable panel, and can be bent along line AA (vertical trace extension direction) or along line BB (parallel trace extension direction). There are a plurality of traces 110 at the edge of the panel 100 for conducting signals. As shown, the panel 100 has a plurality of locally thickened

regions

112, 114, and 116 at the locations of the traces 110.

Fig. 1B is a schematic cross-sectional view of a trace (conductive stack) local along line CC in the locally thickened region 114 of fig. 1A, according to some embodiments. Conductive stack 120 includes a substrate 122, a metal layer 124 over substrate 122, a thickening layer 126 over metal layer 124, and a conductive layer 128 over thickening layer 126. The substrate 122, the metal layer 124, and the conductive layer 128 are layers in other areas of the trace 110. In some embodiments, a thickening layer 126 is added between the metal layer 124 and the conductive layer 128 in a local area of the trace 110 (e.g., in the conductive stack 120). In other embodiments, the length of the thickening layer 126 along the extending direction of the trace 110 is not greater than the length of the conductive layer 128.

In some embodiments, the material of the substrate 122 may be polyethylene terephthalate (PET), Cyclic Olefin Polymer (COP), Polyimide (PI), Polycarbonate (PC), Colorless Polyimide (CPI), polyethylene naphthalate (PEN), or the like. In some embodiments, the material of the metal layer 124 may be gold, palladium, silver, copper, nickel, alloys thereof, or combinations thereof. In some embodiments, the material of the conductive layer 118 may be Indium Tin Oxide (ITO), nano silver wire, metal mesh, conductive polymer (e.g., poly (3, 4-ethylenedioxythiophene)/poly (styrenesulfonic acid) (PEDOT/PSS)), carbon nanotubes, graphene, or the like.

In some embodiments, the material of thickening layer 126 may be a metal, a non-metal, or a composite conductive material. The metal may be, for example, gold, palladium, silver, copper, nickel, alloys thereof, or combinations thereof. The non-metal may be, for example, a polymeric insulating material (e.g., a protective layer) or a polymeric conductive material (e.g., PEDOT/PSS). The composite conductive material may be, for example, nano silver/carbon black/carbon nanotubes/graphene-doped metal particles and resins. In some embodiments, the material of the thickening layer has good connection and adhesion with the material of the layer below it to form a good conductor.

In some embodiments, the formation of the thickening layer may be achieved by a patterning process, such as: photolithography (lithographics), Ink Jet Printing (IJP), Spray printing (Spray), Screen printing (Screen printing), Flexo printing (Flexo printing), or the like.

Referring to fig. 1C, in other embodiments, the trace portion (conductive stack) along line CC in the locally thickened region 114 of fig. 1A is the conductive stack 130 shown in fig. 1C. Conductive stack 130 includes substrate 132, conductive layer 134 over substrate 132, metal layer 136 over conductive layer 134, and thickening layer 138 over metal layer 136. The substrate 132, the conductive layer 134, and the metal layer 136 are layers in other areas of the trace 110. In some embodiments, a thickening layer 138 is added over conductive layer 134 and metal layer 136 in a local area of trace 110 (e.g., in conductive stack 130). In other embodiments, the length of the thickening layer 138 along the extending direction of the trace 110 is not greater than the length of the conductive layer 134.

The materials of the layers of the conductive stack 130 may be the same as those of the layers of the conductive stack 120 of fig. 1B, and may be formed by the same processes as described above.

Referring to fig. 1D, in still other embodiments, the trace portion (conductive stack) along line CC in the locally thickened region 114 of fig. 1A is the conductive stack 140 shown in fig. 1D. Conductive stack 140 includes a substrate 142, a metal layer 144 over substrate 142, a conductive layer 146 over metal layer 144, and a thickening layer 148 over conductive layer 146. The substrate 142, the metal layer 144, and the conductive layer 146 are layers in other areas of the trace 110. In some embodiments, a thickening layer 148 is added over the metal layer 144 and the conductive layer 146 in a local area of the trace 110 (e.g., in the conductive stack 140). In other embodiments, the length of the thickening layer 138 along the extending direction of the trace 110 is not greater than the length of the conductive layer 134.

The materials of the layers of the conductive stack 140 may be the same as the materials of the layers of the conductive stack 120 of fig. 1B, and may be formed by the same processes as described above.

Please refer to fig. 1E, which is an enlarged view of the partially thickened region 114 of fig. 1A. The width dimension of the trace 110 is W₁Between tracksPitch size P₁The dotted line is the bending line of the device when bent. In some embodiments, the area having the thickening layer is in a portion of the routing line of the non-display area. In the first direction (the direction in which the traces extend, i.e., the y direction), the length of the region with the thickening layer is L₁。

In some embodiments, in the second direction (the direction perpendicular to the first direction, i.e. the x direction), the width of the thickening layer may be the width of a single trace 110, i.e. the respective thickening layers are located in different traces. That is, the width dimension of the thickening layer is W₁. In other embodiments, when the thickening layer is made of a non-metal material, such as a polymer material, an integral thickening layer can be formed within the range of the traces 110, i.e., a single thickening layer covers the conductive layers of the traces 110. That is, when there are N tracks, the width dimension Wt of the thickening layer is equal to or slightly larger than nxw₁+(N-1)x P₁. Alternatively, the width dimension W of the thickening layer_tIs about equal to N x (W)₁+P₁). Thus, the width dimension of the thickening layer in the second direction may range between about W₁And (W)₁+P₁) x N, respectively.

Fig. 2A and 2B are schematic diagrams illustrating a bending region of a conductive layer stack in a bent state. The length of the area covered by the thickening layer is related to the radius of curvature and the bending angle at bending. In the conductive stack 20 illustrated in fig. 2A, the conductive stack extends along a first direction (x-direction), and the thickening layer 26 is located above the substrate 22 and the routing material layer (metal or nonmetal) 24. In FIG. 2A, the radius of curvature is R₁The angle of bending is theta₁The length of the thickening layer 26 is W₁. In the conductive stack 30 of fig. 2B, the radius of curvature is R₂The angle of bending is theta₂The thickening layer 36 is located above the substrate 32 and the trace material layer 34 and has a length W₂。

In some embodiments, the length of the thickening layer in the first direction is dependent on the radius of curvature and the angle of bending of the foldable electronic device. In some embodiments, the radius of curvature of the conductive layer stack is 1 mm, the bend angle is 180 degrees, and the length of the thickening layer along the first direction is at least 3 mm.

In some embodiments, the conductive layer stack extends along a first direction, a length of the thickening layer in the first direction in the bending region depends on a radius of curvature of the electronic component device during bending and an angle of bending, and the length of the thickening layer at least needs to be greater than an arc length range of 180 ° corresponding to the radius of curvature.

In some embodiments, the thickening layer has a length in a range greater than 15 millimeters (mm), and the angle between the bending axis and the two ends of the thickening layer is 180 to 360 degrees (depending on the length of the thickening layer); compared with a conductive stack without a thickening layer, the conductive stack in the embodiment of the disclosure can increase the amount of stress strain in bending by 0.1 to 10%, and the curvature radius of the conductive stack can be reduced by 0.5 to 3 mm.

In some embodiments, the conductive layer stack extends in a first direction, the length of the thickening layer in the first direction is greater than 9 mm, and when bent with a radius of curvature of about 3 mm, the center point of the radius of curvature makes an angle of about 180 ° with both ends of the thickening layer.

In other embodiments, the stack of conductive layers extends in a first direction, the length of the thickening layer in the first direction is greater than 15 mm, and when bent at a radius of curvature of about 5 mm, the center point of the radius of curvature is at an angle of about 180 ° to the ends of the thickening layer.

In some embodiments, the conductive layer extends along a first direction, and a ratio of a length of the thickening layer in the first direction to a length of the conductive layer extending along the first direction is 0.001 to 1, for example, 0.001, 0.005, 0.01, 0.02, 0.05, 0.08, 0.1, 0.2, 0.5, 0.8.

In some embodiments, the conductive stack of the present disclosure can be applied to traces of a foldable electronic device. A foldable electronic device includes a first portion, a refoldable region connecting the first portion, and a second portion connecting the refoldable region. The wiring comprises a thickening layer in a repeatedly folding area and is positioned on the tensile stress bearing side when the foldable electronic device is folded so as to reduce the risk of breakage of the wiring. Wherein the angle of the first portion and the second portion when the foldable electronic device is unfolded may be 150 degrees-180 degrees or 180 degrees-210 degrees, and the angle of the first portion and the second portion when the foldable electronic device is folded may be 0 degrees-30 degrees or 330 degrees-360 degrees.

When the conductive layer stack is formed as a conductive trace applied to the foldable electronic device, the resistance change (increase) of the conductive trace should be as small as possible under the effect of multiple bending stresses. Once the conductive traces are cracked or broken, the resistance of the conductive traces increases and even fails, which may lead to performance degradation and even failure of the foldable electronic device. Wherein a break as defined herein is an increase in the resistance of the conductive trace by more than 10%.

The test results of the bending test of the conductive layer stack according to the embodiment are described below with reference to comparative examples (see fig. 3A to 3B) and experimental examples (see fig. 4A to 4C).

Bending tests were performed using a bending machine model DMLHP-CS manufactured by Yuasa Battery corporation to test the conductive stacks of the examples and comparative examples. The test conditions were a radius of curvature of 3 mm, a bending frequency of 30 times per minute and a maximum folding force of 4 Nm. The number of bends and the percent change in resistance of the different conductive layer stacks were then recorded.

Fig. 3A is a schematic diagram of a conductive layer stack 40 in a bent state according to some comparative examples; fig. 3B is a schematic diagram illustrating the conductive layer stack 40 in an unbent state. The conductive stack 40 includes a substrate 42, and a metal layer 44 over the substrate 42. Further, the line length of the conductive laminated structure 40 is 100 μm. In the conductive stack 40, the substrate 42 is made of PET, has a thickness of 50 μm, and has a Young's modulus of 2-3 GP. The metal layer 44 is a copper layer with a thickness of 0.3 μm and a Young's modulus of 140 GPa. The dashed line shown in fig. 3B is the position of the neutral axis when bent.

The following table is the result of a bending test performed on the conductive layer stack of different comparative examples at a radius of curvature of 3 mm and an angle of 180 °. In which the metal layer (copper layer) in the comparative examples was formed by sputtering or by different electroplating processes (i.e., electroless plating (one), (two), (three)).

Watch 1

As can be seen from the table, after 2 ten thousand folds with a curvature radius of 3 mm, the resistance of the conductive layer stack of each of the comparative examples was significantly increased. The resistance of the conductive stacked wiring formed by adopting the processes of electroplating (I), electroplating (II) and electroplating (III) is changed by more than 10 percent.

Fig. 4A is a schematic diagram of a conductive layer stack 50 in an unbent state according to some experimental examples. Conductive stack 50 includes a substrate 52, a conductive layer 54 over substrate 52, a metal layer 56 over conductive layer 54, and a thickening layer 58 over metal layer 56. Wherein, the material of thickening layer 58 is copper. The dashed line shown in fig. 4A is the position of the neutral axis when bent.

Fig. 4B is a schematic diagram of the conductive layer stack 60 in an unbent state according to some experimental examples. Conductive stack 60 includes a substrate 62, a conductive layer 64 over substrate 62, a metal layer 66 over conductive layer 64, and a thickening layer 68 over metal layer 66. The substrate 62 was formed of PET and had a thickness of 50 μm. The conductive layer 64 comprises a nano-silver material and has a thickness of 0.2-0.5 μm. The metal layer 66 is made of copper and has a thickness of 0.2-0.5 μm. The thickening layer 68 is a polymer layer made of acrylic and has a thickness of 5 to 10 μm. The dashed line shown in fig. 4B is the position of the neutral axis when bent.

Table two below shows the results of bending tests performed on different conductive layer stacks of the embodiment shown in fig. 4B, with a radius of curvature of 3 mm and an angle of 180 °. Wherein the control was a conductive stack of uncoated polymer (without a thickening layer).

Watch two

As can be seen from table two, after 4 ten thousand folds, the resistance of the conductive layer stack of each of the above embodiments has no significant change; in contrast, the trace resistance of the conductive polymer-uncoated stack rises significantly, representing a case of wire breakage. Thus, the conductive stack of the example had better flex resistance, significantly better than the control conductive stack, which was not coated with polymer.

Fig. 4C is a schematic diagram of the conductive layer stack 70 in an unbent state according to some experimental examples. Conductive stack 70 includes a substrate 72, a conductive layer 74 over substrate 72, a metal layer 76 over conductive layer 74, a first polymer layer 78 over metal layer 76, and a second polymer layer 80 over first polymer layer 78. That is, in conductive stack 70, the thickening layer is a multilayer formed of a heterogeneous polymer, including first polymer layer 78 and second polymer layer 80. In the conductive stack 70, the substrate 72 is formed of PET and has a thickness of 50 microns. The conductive layer 74 includes a nano-silver material and has a thickness of 100nm or less. The metal layer 76 is made of copper and has a thickness of 0.2-0.5 μm. The material of the first polymer layer 78 is Optical Clear Adhesive (OCA) with a thickness of 50 microns. The material of the second polymer layer 80 is PET and has a thickness of 50 microns. The dashed line shown in fig. 4C is the position of the neutral axis when bent.

Table three below shows the results of bending tests performed on the conductive layer stack of different embodiments at a curvature radius of 3 mm and an angle of 180 °. Wherein the control was a conductive stack of uncoated polymer (without a thickening layer). In table three, the conductive stack including the OCA layer/PET layer corresponds to the structure of the embodiment shown in fig. 4C.

Watch III

As can be seen from table three, after 4 ten thousand folds, the resistance of the conductive stack of the embodiment having the first polymer layer and the second polymer layer did not change significantly; after 6 ten thousand folds, 16 ten thousand folds, 5 thousand folds, and 20 ten thousand folds, the resistance of the conductive layer stack does not change significantly. That is, after being folded several times, the conductive layer stack is not broken. Thus, the conductive stacks of these examples have better flex resistance, significantly better than the control conductive stack without the polymer coating.

Fig. 5A-5D illustrate schematic diagrams of conductive layer stacks, according to some embodiments of the present disclosure.

Fig. 5A shows a conductive stack 210 including a substrate 212, a wire-walking material layer 214 over the substrate 212, and a thickening layer 216 over the wire-walking material layer 214. The material of the wire-passing material layer 214 may be metal, nonmetal, or a combination thereof. The material of the thickening layer 216 may be a metal, a non-metal, or a composite conductive material.

In some embodiments, when the material of the thickening layer 216 is metal, the ratio of the thickness of the thickening layer 216 to the thickness of the wire-moving material layer 214 is 0.05-5, for example, 0.05-0.5, 0.1-1, 0.5-2, or 2-5.

In some embodiments, when the material of the thickening layer 216 is a non-metal or composite conductive material, the ratio of the thickness of the thickening layer 216 to the thickness of the wire-moving material layer 214 is 0.1 to 50, such as 0.1 to 10, 10 to 20, or 20 to 50.

In some embodiments, the thickness (unit: μm) multiplied by the Young's modulus (unit: Gpa) of the substrate 212 of the conductive laminate 210 is about 100 to 300, the thickness multiplied by the Young's modulus of the wire-moving material layer 214 is about 20 to 70, the material of the thickening layer 216 is a metal, and the thickness multiplied by the Young's modulus of the thickening layer 216 is about 5 to 30.

In some embodiments, the thickness times the Young's modulus of the substrate 212 of the conductive laminate 210 is about 100 to 300, the thickness times the Young's modulus of the wire layer 214 is about 20 to 70, the material of the thickening layer 216 is a non-metallic or composite conductive material, and the thickness times the Young's modulus of the thickening layer 216 is about 2 to 60.

Fig. 5B shows a conductive stack 220 comprising a substrate 222, a wire-feed material layer 224 over the substrate 222, a first polymer layer 226 over the wire-feed material layer 224, and a second polymer layer 228 over the first polymer layer 226. In the conductive stack 220, the material of the substrate 222 and the wire-feed material layer 224 is similar to the substrate 212 and the wire-feed material layer 214 of the conductive stack 210 shown in fig. 5A. In conductive stack 220, the thickening layer is a multilayer formed of heterogeneous polymers, including a first polymer layer 226 and a second polymer layer 228. The first polymer layer 226 and the second polymer layer 228 are different polymer materials. In some embodiments, the ratio of the young's modulus of first polymer layer 226 to second polymer layer 228 is about 10³～10⁶For example, first polymer layer 226 is formed of OCA and second polymer layer 228 is formed of PET. In the conductive stack 220, the ratio of the thickness of the first polymer layer 226 to the thickness of the wire feed layer 224 is about 30 to 100, the ratio of the thickness of the second polymer layer 228 to the thickness of the wire feed layer 214 is about 30 to 100, and the ratio of the thickness of the first polymer layer to the thickness of the second polymer layer is about 0.5 to 2.

In some embodiments, the thickness times Young's modulus of the substrate 222 of the conductive stack 220 is about 100 to 300, the thickness times Young's modulus of the wire layer 224 is about 20 to 70, the thickness times Young's modulus of the first polymer layer 226 is about 2 to 60, and the thickness times Young's modulus of the second polymer layer 228 is about 100 to 300.

Fig. 5C shows a conductive layer stack 230 comprising a substrate 232, a Catalyst layer (Catalyst layer)234 over the substrate 232, a conductive layer 236 over the Catalyst layer 234, and a thickening layer 238 over the conductive layer 236. In conductive stack 230, substrate 232, and thickening layer 238 are similar to substrate 212, and thickening layer 216 in conductive stack 210 shown in fig. 5A. In some embodiments, the material of catalyst layer 234 may be any one of palladium, rhodium, platinum, iridium, osmium, gold, nickel, iron, and the like. In the conductive layer stack 230, the conductive layer 236 is made of metal, such as copper layer formed on the catalyst layer 234 by electroless plating, and the ratio of the thickness of the conductive layer 236 to the thickness of the catalyst layer 234 is about 0.5-5, or about 2-10.

Fig. 5D shows a conductive layer stack 240 comprising a substrate 242, a catalyst layer 244 over the substrate 232, a conductive layer 246 over the catalyst layer 244, a first polymer layer 248 over the conductive layer 246, and a second polymer layer 250 over the first polymer layer 248. In conductive stack 240, substrate 242, first polymer layer 248, and second polymer layer 250 are similar to substrate 222, first polymer layer 226, and second polymer layer 228 in conductive stack 220 shown in fig. 5B. In some embodiments, the material of the catalyst layer 244 may be any one of palladium, rhodium, platinum, iridium, osmium, gold, nickel, iron, and the like. In the conductive layer stack 240, the material of the conductive layer 246 is metal, such as a copper layer formed by an electroless plating process on the catalyst layer 244, and the ratio of the thickness of the conductive layer 246 to the thickness of the catalyst layer 244 is about 0.5 to 5, or about 2 to 10.

Fig. 6A-6F are schematic diagrams illustrating a conductive layer stack applied to a single-sided foldable electronic device according to some embodiments.

Fig. 6A is a schematic view of the conductive stack 310 when it is folded in a U-shape, and fig. 6B is a schematic view of the conductive stack 310 when it is unfolded.

Conductive stack 310 includes a substrate 312, a metal layer 314 over substrate 312, and a conductive layer 318 over the metal layer, with a thickening layer 316 between metal layer 314 and conductive layer 318 formed at the bend. In some embodiments, at the bend, the metal layer 314 is first locally thickened, forming a thickened layer 316 of a material that is a metal or composite conductive composite, followed by a conductive layer 318 comprising silver nanowires.

Fig. 6C is a schematic view of the conductive stack 330 when folded in a U-shape, and fig. 6D is a schematic view of the conductive stack 330 when unfolded.

Conductive stack 330 includes a substrate 332, a metal layer 334 over substrate 332, and a conductive layer 336 over the metal layer, with a thickening layer 338 over conductive layer 336 formed at the bends. In some embodiments, at the bend, a conductive layer 336 comprising silver nanowires is applied, followed by locally forming a thickening layer 338 of a material that is metallic, non-metallic, or a composite conductive material.

Fig. 6E is a schematic view of the conductive stack 350 folded in a U-shape, and fig. 6F is a schematic view of the conductive stack 350 unfolded.

Conductive layer stack 350 includes a substrate 352, a conductive layer 354 over substrate 352, and a metal layer 356 over conductive layer 354, with a thickening layer 358 over metal layer 356 formed at the bends. In some embodiments, a thickened layer 358 of a material that is metallic, non-metallic, or a composite conductive material is formed locally over the metal layer 356 at the bend.

Fig. 7A-7F are schematic diagrams illustrating a conductive stack applied to a dual-side foldable electronic device according to some embodiments.

Fig. 7A is a schematic diagram of the conductive stack 410 when folded in an S-shape, and fig. 7B is a schematic diagram of the conductive stack 410 when unfolded.

The conductive layer stack 410 includes a structural layer 414 with double-sided metal films,

conductive layers

412 and 418 on both sides of the structural layer 414 with double-sided metal films, and a thickening layer 416 at the bend.

The structural layer 414 with double-sided metal film includes a substrate 414B, and

metal layers

414A and 414C are formed on both sides of the substrate 414B. At the bends, a thickening layer 416 is located between metal layers 414A and conductive layer 412, and between metal layer 414C and conductive layer 418. In some embodiments, at the bend, the metal layer 314 is first locally thickened, forming a thickened layer 416 of a metal or composite conductive material, followed by application of

conductive layers

412 and 418 comprising silver nanowires.

Fig. 7C is a schematic diagram of the conductive stack 430 when folded in an S-shape, and fig. 7D is a schematic diagram of the conductive stack 430 when unfolded.

The conductive layer stack 430 includes a structural layer 434 with double-sided metal films,

conductive layers

432 and 436 on both sides of the structural layer 434 with double-sided metal films, and a thickening layer 438 at the bend.

The structural layer 434 having the double-sided metal film includes a substrate 434B, and

metal layers

434A and 434C are formed on both sides of the substrate 434B. At the bends, a thickening layer 438 is located over

conductive layers

432 and 436. In some embodiments, after the

conductive layers

432 and 436 comprising the silver nanowires are applied, a thickening layer 438 of a metal, non-metal, or composite conductive material is formed at the bend.

Fig. 7E is a schematic diagram of the conductive stack 450 folded in an S-shape, and fig. 7F is a schematic diagram of the conductive stack 450 unfolded.

Conductive stack 450 includes a structural layer 454 having a double-sided conductive film (e.g., a transparent conductive layer),

metal layers

452 and 456 on both sides of structural layer 454 having a double-sided conductive film, and a thickening layer 458 at the bend.

The structure layer 454 with the double-sided conductive film includes a substrate 454B, and

conductive layers

454A and 454C are formed on both sides of the substrate 454B. In some embodiments, a thickening layer 458 of a material that is a metal, a non-metal, or a composite conductive material is formed locally over

metal layers

452 and 456 at the bends.

Methods of fabricating a folded device having a conductive stack with a thickened layer are provided below.

Fig. 8A-8I illustrate a process for forming a folded electronic device according to some embodiments, which includes a single-Sided Metal Film (SMF), a Selectively Grown Metal (SGM), and a conductive layer in that order, wherein the thickening layer is made of a metal material.

As shown in fig. 8A, a substrate 502 having a metal layer 504 is provided. A metal material such as copper may be formed on the substrate 502 using sputtering or plating.

As shown in fig. 8B, a photoresist layer 506 is then formed on the metal layer 504, and exposure and development are performed to pattern the photoresist layer 506.

As shown in fig. 8C, an etching process is then performed to etch the portion of the metal layer 504 not covered by the patterned photoresist layer 506, thereby forming a patterned metal layer 504. The photoresist layer 506 is then stripped.

As shown in fig. 8D, a photoresist layer 510 is formed between the spaces of the patterned metal layer 504, and exposed and developed. A thickening layer 508 is then selectively grown over metal layer 504. In some embodiments, the copper material is formed over the metal layer 504 via sputtering or electroplating.

As shown in fig. 8E, photoresist layer 510 is removed and conductive layer 512 is disposed on substrate 502, metal layer 504, and thickening layer 508. In some embodiments, a conductive material containing nano silver wires or ITO may be formed into the conductive layer 512 by way of coating.

As shown in fig. 8F, a photoresist layer 514 is provided, and exposed and developed to form a patterned photoresist layer 514.

As shown in fig. 8G, an etch is then performed to etch the conductive layer 512, the thickening layer 508, and the metal layer 504 that are not covered by the patterned photoresist layer. Thus, a plurality of spaced-apart traces are formed.

As shown in fig. 8H, the photoresist layer 514 is stripped.

As shown in fig. 8I, a protective layer (over coating)516 is disposed over substrate 502, metal layer 504, thickening layer 508, and conductive layer 512. In the structure shown in fig. 8I, a thickening layer 508 is located between metal layer 504 and conductive layer 512 in the trace.

Fig. 9A-9J illustrate a process for forming a folded electronic device having layers that sequentially include a single-sided metal film, a conductive layer, and a selectively grown metal, wherein the thickening layer is a metal material, according to some embodiments.

As shown in fig. 9A, a substrate 522 having a metal layer 524 is provided. A metal material such as copper may be formed on the substrate 522 using sputtering or plating.

As shown in fig. 9B, a photoresist layer 526 is formed over the metal layer 524, and exposed and developed to form a patterned photoresist layer 526.

As shown in fig. 9C, an etching process is performed to etch the portion of the metal layer 524 not covered by the patterned photoresist layer 526, thereby forming a patterned metal layer. The photoresist layer 526 is then stripped.

As shown in fig. 9D, a conductive layer 528 is disposed over substrate 522 and metal layer 524. Conductive material containing nano-silver wires or ITO may be formed into conductive layer 528 via coating.

As shown in fig. 9E, a photoresist layer 530 is formed, and exposed and developed to form a patterned photoresist layer 530.

As shown in fig. 9F, a thickening layer 532 is disposed over the conductive layer in areas not covered by the patterned photoresist layer 530. In some embodiments, the copper material may be sputtered or plated on the conductive layer 528 through selective growth.

As shown in fig. 9G, the photoresist layer 530 is stripped.

As shown in fig. 9H, a photoresist layer 534 is formed, and the patterned photoresist layer 534 is formed by exposure and development.

As shown in fig. 9I, an etch is then performed to remove the thickening layer 532, the conductive layer 528, and the metal layer 524 that are not covered by the patterned photoresist layer 534. Thus, a plurality of spaced-apart traces are formed. The photoresist layer 534 is stripped.

As shown in fig. 9J, a protective layer 536 is disposed over the substrate 522, the metal layer 524, the conductive layer 528, and the thickening layer 532. In the structure shown in fig. 9J, a thickening layer 532 is located over both the metal layer 524 and the conductive layer 528 in the trace.

Fig. 10A-10G illustrate a process for forming a folded electronic device having layers that sequentially include a conductive layer, a single-sided metal film, and a selectively grown metal, wherein the thickening layer is a metal material, according to some embodiments.

As shown in fig. 10A, a substrate 602 including a conductive layer 604 (transparent conductive film) is provided first, and then a metal layer 606 is provided over the conductive layer 604. In some embodiments, the copper material can be formed over the conductive layer 604 by sputtering or electroplating.

As shown in fig. 10B, a photoresist layer 608 is formed, and exposed and developed to form a patterned photoresist layer 608.

As shown in fig. 10C, a thickening layer 610 is disposed over the portion of the metal layer 606 not covered by the photoresist layer 608. In some embodiments, the copper material may be disposed on the metal layer 606 by selectively growing the metal layer, such as sputtering or electroplating.

As shown in fig. 10D, the photoresist layer 608 is stripped.

As shown in fig. 10E, a photoresist layer 612 is disposed over the thickening layer 610 and the metal layer 606, and is exposed and developed to form a patterned photoresist layer 612.

As shown in fig. 10F, an etch is then performed to remove the thickening layer 610, the metal layer, and the conductive layer 604 that are not covered by the patterned photoresist layer 612. Thus, a plurality of spaced-apart traces are formed.

As shown in fig. 10G, the metal layer 606 in the intermediate area (e.g., the display area that will later be formed into an electronic device) is removed. A protective layer 614 is then disposed over the thickening layer 610, the metal layer 606, and the conductive layer 604. In the structure shown in fig. 10G, a thickening layer 610 is located over both the conductive layer 604 and the metal layer 606 in the trace.

Fig. 11A-11H illustrate a process for forming a folded electronic device having layers including a metal layer, a conductive layer, and a thickening layer in that order, wherein the thickening layer is a non-metallic material, such as a polymeric material, according to some embodiments.

As shown in fig. 11A, a substrate 702 having a metal layer 704 is provided. A metallic material such as copper may be formed on the substrate 702 using sputtering or plating.

As shown in fig. 11B, a photoresist layer 706 is formed over the metal layer 704, and exposed and developed to form a patterned photoresist layer 706.

As shown in fig. 11C, the metal layer 704 not covered by the patterned photoresist layer 706 is etched. The photoresist layer 706 is then stripped.

As shown in fig. 11D, a conductive layer 708 is disposed over the substrate 702 and the metal layer 704. Conductive material containing nano-silver wires or ITO may be formed into conductive layer 708 by way of coating.

As shown in fig. 11E, a photoresist layer 710 is formed over the conductive layer 708, and exposed and developed to form a patterned photoresist layer 710.

As shown in fig. 11F, an etching process is performed to remove the portions of the conductive layer 708 and the metal layer 704 that are not covered by the patterned photoresist layer 710, so as to form a plurality of separated traces.

As shown in fig. 11G, the photoresist layer 710 is then stripped. In subsequent processes, a protection layer 712 is formed on each trace. The protective layer 712 may be formed of a polymer material.

As shown in fig. 11H, a thickening layer 714 is then formed over the protective layer 712. The thickening 714 may be formed of another polymer material than the protective layer 712.

Fig. 12A-12H illustrate a process of forming a folded electronic device having layers including, in order, a conductive layer, a metal layer, and a thickening layer, wherein the thickening layer is a non-metallic material, such as a polymeric material, according to some embodiments.

As shown in fig. 12A, a substrate 722 including a conductive layer 724 is provided, and the conductive layer 724 may include, for example, a nano silver wire. In some embodiments, a protective layer (not shown) is over the conductive layer 724. Metal layer 726 is then disposed over conductive layer 724. In some embodiments, the copper material may be formed over the conductive layer 724 by sputtering or electroplating.

As shown in fig. 12B, a photoresist layer 728 is formed over the metal layer 726, and exposed and developed to form a patterned photoresist layer 728.

As shown in fig. 12C, the metal layer 726 and the conductive layer 724, which are not covered by the patterned photoresist layer 728, are etched. Thus forming a plurality of spaced apart traces.

As shown in fig. 12D, photoresist layer 728 in the middle region is stripped.

As shown in fig. 12E, the metal layer 726 in the middle region is removed.

As shown in fig. 12F, the photoresist layer 728 is stripped.

As shown in fig. 12G, a first polymer layer 730 is formed over the respective traces and over the conductive layer 724.

As shown in fig. 12H, a second polymer layer 732 is formed over substrate 722, conductive layer 724, and metal layer 726 at the periphery of the device (i.e., in the non-display region). In the structure shown in fig. 12H, the second polymer layer 732, or the combination of the first polymer layer 730 and the second polymer layer 732, corresponds to a thickening layer of the traces.

The conductive layer folding structure of the disclosure enables the folding electronic device to have a smaller bending curvature radius, enhances the foldability, and can still have better reliability for routing after being bent for many times, thereby improving the product quality and prolonging the service life of the device.

The foregoing outlines several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments or examples described herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

1. A conductive layer stack, comprising:

a conductive layer extending along a first direction; and

and the thickening layer is arranged above or below the conductive layer, and the conductive layer stack can bear the fracture of more than 40000 times when the conductive layer stack is bent by 180 degrees in a direction perpendicular to or parallel to the first direction, wherein the curvature radius R is 3 mm.

2. The conductive stack of claim 1, wherein the length of the thickening layer in the first direction is greater than 9 mm and does not exceed the length of the conductive layer extending in the first direction.

3. The conductive stack of claim 2, wherein the length of the thickening layer in the first direction is greater than 15 mm and does not exceed the length of the conductive layer extending in the first direction.

4. The conductive layer stack of claim 1, wherein an angle between a bending axis of the conductive layer stack and two ends of the thickening layer is 180 ° to 360 °.

5. The conductive stack of claim 1, wherein a ratio of a length of the thickening layer in the first direction to a length of the conductive layer extending along the first direction is 0.001-1.

6. The conductive stack of claim 1, wherein the thickening layer increases the amount of stress strain in the conductive stack when the conductive stack is bent by 0.1 to 10%, and the radius of curvature of the conductive stack is reduced by 0.5 to 3 mm.

7. The conductive stack of claim 1, wherein the thickening layer is located on a stress-stretching side of the conductive stack when the conductive stack is bent.

8. A foldable electronic device, comprising the conductive stack of any one of claims 1 to 7.

9. A foldable electronic device, comprising:

a display area; and

a non-display area located outside the display area, wherein the non-display area has a plurality of wires extending along a first direction, each of the plurality of wires includes:

a substrate, and

a conductive layer over the substrate;

the non-display area has a local thickened area including a bending part of the foldable electronic device, and each of the plurality of wires in the local thickened area further includes a thickened layer above or below the conductive layer and located on a stress stretching side of the foldable electronic device when the foldable electronic device is bent.

10. The foldable electronic device of claim 9, wherein the locally thickened region has a width extending along a second direction perpendicular to the first direction, and one of the traces has a width W₁The distance between the routing lines is P₁The number of the routing lines is N, and the width range of the local thickening area is between W₁To (W)₁+P₁) x N, respectively.

11. The foldable electronic device of claim 9, wherein the length of the thickening layer along the first direction is greater than 3 mm.

12. The foldable electronic device of claim 9, wherein the thickening layer is formed of a metal material, and a ratio of the thickness of the thickening layer to the thickness of the conductive layer is 0.05-5.

13. The foldable electronic device of claim 9, wherein the thickening layer is formed of a non-metallic material or a composite conductive material, and a ratio of the thickness of the thickening layer to the thickness of the conductive layer is 0.1-50.

14. The foldable electronic device of claim 9, wherein the thickening layer is made of a metal material, and the value of the thickness of the substrate multiplied by the Young's modulus of the substrate is 100-300, the value of the thickness of the conductive layer multiplied by the Young's modulus of the conductive layer is 20-70, and the value of the thickness of the thickening layer multiplied by the Young's modulus of the thickening layer is 5-30.

15. The foldable electronic device of claim 9, wherein the thickening layer is formed of a non-metallic material or a composite conductive material, and the value of the thickness of the substrate multiplied by the Young's modulus of the substrate is 100-300, the value of the thickness of the conductive layer multiplied by the Young's modulus of the conductive layer is 20-70, and the value of the thickness of the thickening layer multiplied by the Young's modulus is 2-60.

16. The foldable electronic device of claim 9, wherein the thickening layer comprises:

a first polymer layer; and

a second polymer layer over the first polymer layer, wherein the material of the first polymer layer is different from the material of the second polymer layer.

17. The foldable electronic device of claim 16, wherein the ratio of the young's modulus of the first polymer layer to the young's modulus of the second polymer layer is 10³～10⁶。

18. The foldable electronic device of claim 16, wherein a ratio of the thickness of the first polymer to the thickness of the conductive layer is 30 to 100, a ratio of the thickness of the second polymer to the thickness of the conductive layer is 30 to 100, and a ratio of the thickness of the first polymer to the thickness of the second polymer is 0.5 to 2.