KR100967362B1 - Stretchable and bendable wiring structure and fabricating method thereof - Google Patents

Abstract

The present invention is a flexible substrate having an uneven structure; And a flexible wiring structure including a conductive wiring patterned on the flexible substrate, wherein the conductive wiring is bent in a vertical direction of the flexible substrate so that stress can be dispersed while deforming together with the deformation of the flexible substrate. The present invention provides a flexible wiring structure laminated thereon while being in close contact with a surface thereof and a method of manufacturing the same. In the flexible wiring structure according to the present invention, biomedical, robotics, displays, and other flexible electronics are made because the wiring is less mechanically stressed in various forms of deformation such as biaxial stretching or bending in addition to uniaxial stretching of the flexible substrate. There is an advantage to increase the reliability of the wiring used in the device field.

Stretch, Bending, Flexible Wiring Structures

Description

Stretchable and bendable wiring structure and manufacturing method thereof {Stretchable and bendable wiring structure and fabricating method

The present invention relates to a wiring structure capable of stretching and bending and a method of manufacturing the same, and more particularly, to a wiring structure and a method of manufacturing the same, by patterning conductive wires of uneven structure on a flexible substrate to withstand deformation of stretching and bending. .

If the wire transferred on the flexible substrate is subjected to mechanical stress such as stretching or bending, there is a problem that the sheet resistance is increased and the reliability is deteriorated by the mechanical defect of the wiring. In particular, sensor skins for robotics or medical devices, conformal displays, and electroactive polymers require electrical interconnects, i.e., flexible wiring structures that can withstand various reversible stretching and other variations.

In the related art, S.P. Lacour et al., "Design and Performance of thin Metal Film Interconnects for Skin-Like Electronic Circuits", IEEE Electron Device Letters, vol. 25, no. 4, p. 179-181, April 2004, proposes a new flexible wiring structure.

1 is a view showing a step of manufacturing a flexible wiring structure according to the prior art. Referring to this, the conductor structure is resistant to stretching by pre-stretching the PDMS substrate in one direction and performing electrical wiring thereon so that the electrical wiring has a wrinkled band shape when the pre-stretched substrate is restored to its original state. Disclosed is a manufacturing method of.

In this case, however, stress in one direction can be prevented, but stress due to stretching or bending in any direction cannot be distributed.

In particular, the method of electrical wiring with the substrate stretched as described above is a lot of difficulties in manufacturing, and it is almost impossible to obtain a uniform quality of electrical wiring for each flexible substrate having different elasticity.

Other D.B. Brosteaux et al., "Design and Fabrication of Elastic Interconnections for Stretchable Electronic Circuits", IEEE Electron Device Letters, vol. 28, no. A method of forming a horseshoe-shaped flexible wiring on or inside a PDMS substrate is disclosed in a photolithography and electroplating process on July 7, 2007.

2 is a view showing a manufacturing step of the flexible wiring structure according to the prior art.

Referring to this, the conventional wire transfer method twists the wire into a horseshoe shape and takes the shape of protecting the wire from mechanical stress in the transverse direction. Although horseshoe-shaped wiring disperses stress, this wiring structure has only stress dispersing effect in one axial direction, and there is little reliability for stress in any direction.

Therefore, unlike the flexible wiring structure of the prior art, a new type of flexible wiring structure capable of distributing stress even in deformation in any direction is required.

Accordingly, the present invention provides a new type of flexible wiring structure and its solution in order to solve the problem that the sheet resistance is increased and the reliability is deteriorated by the mechanical defect of the wiring when the wire transferred on the flexible substrate is subjected to mechanical stress such as stretching or bending. To provide a manufacturing method.

The present invention as a means for solving the above problems

Flexible substrate having an uneven structure; And a flexible wiring structure including a conductive wiring patterned on the flexible substrate,

According to the deformation of the flexible substrate, the conductive wiring is provided with a flexible wiring structure laminated while covering the surface closely along the surface of the concave-convex structure that is bent in the vertical direction of the surface of the flexible substrate so that stress can be dispersed together. .

In addition, the present invention to manufacture such a flexible wiring structure

Forming an uneven structure on the flexible substrate; And

Patterning the conductive wiring in a desired shape on the flexible substrate having the concave-convex structure, wherein the conductive wiring is laminated so as to cover and cover at least along the surface of the concave-convex structure;

It provides a method of manufacturing a flexible wiring structure comprising a.

The present invention as another means for solving the above problems

Flexible substrates; Conductive wiring patterned on the flexible substrate; And at least one bridged interconnection patterned on the conductive interconnection and protruding in the vertical direction of the flexible substrate, wherein the flexible interconnection structure includes:

The connection wiring has a clearance between the conductive wiring located below the connection wiring so that the stress can be dispersed while deforming together with the deformation of the flexible substrate, and each end of the connection wiring is in electrical contact with the conductive wiring. Provided are flexible wiring structures.

In addition, the present invention to manufacture such a flexible wiring structure

Patterning conductive wiring of a desired type on the flexible substrate;

Forming at least one protrusion structure on the conductive wiring;

Forming at least one connection wiring on the conductive wiring such that each end portion is in electrical contact with the conductive wiring and covers the surface of the protruding structure; And

Removing the protruding structure so that the connecting line has a bridge structure by passing the upper portion of the place where the protruding structure is removed, thereby forming a free space between the connecting line and the conductive line;

It provides a method of manufacturing a flexible wiring structure comprising a.

The present invention as another means for solving the above problems

Flexible substrates; And a conductive wiring patterned on the flexible substrate, the conductive wiring having an uneven structure curved in a vertical direction along the flexible substrate and having an electrical contact point on the flexible substrate.

According to the deformation of the flexible substrate, the flexible wiring structure having a free space between the adjacent electrical contact points so that the stress can be distributed together.

In addition, the present invention to manufacture such a flexible wiring structure

Forming at least one protrusion on the flexible substrate;

Patterning the conductive wiring of a desired structure across the surface of the projecting structure and being formed on the flexible substrate; And

By removing the protruding structure, the bridge of the conductive wire is formed at each position where the protruding structure is removed, and the electrical contact point is provided with the flexible substrate, and the free space equal to the size of the protruding structure is defined by the bridge of the conductive wire. It provides a method of manufacturing a flexible wiring structure comprising; forming between the lower flexible substrate.

In the flexible wiring structure according to the present invention, biomedical, robotics, displays, and other flexible electronics are made because the wiring is less mechanically stressed in various forms of deformation such as biaxial stretching or bending in addition to uniaxial stretching of the flexible substrate. There is an advantage to increase the reliability of the wiring used in the device field.

Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

3 is a view showing a flexible wiring structure according to a first embodiment of the present invention, (a) shows a two-dimensional uneven structure pattern, and (b) shows a one-dimensional uneven structure pattern.

Referring to FIG. 3A, the flexible wiring structure of the present invention includes a flexible substrate 100 having an uneven structure 101; And a conductive wiring 110 patterned on the flexible substrate 100.

The flexible substrate 100 may be easily deformed and have a thickness and may be a plastic or metal substrate. The flexible substrate 100 is preferably made of a material having elasticity against external magnetic poles. For example, it may be a PDMS material.

The uneven structure 101 is usually arranged two-dimensionally along the surface of the flexible substrate 100. That is, as shown in the right side of FIG. 3 (a), the uneven structure 101 pattern is formed by bending in the biaxial directions of x and y.

Alternatively, the uneven structure 101 may be arranged one-dimensionally along the surface of the flexible substrate 100 in some cases. That is, the uneven structure 101 may be developed only in the uniaxial direction. 3 (b) shows such an example, and the uneven structure 101 pattern is formed to bend only in the x-axis direction.

The uneven structure 101 does not necessarily need to be formed over the entire area of the flexible substrate 100, but may be formed only at a place where some conductive wires 110 are to be patterned.

In addition, in the present specification, the conductive wiring 110 is a general wiring or electrode commonly used for an electronic circuit.

The conductive wire 110 is not limited as long as it is a material that is well communicated with electricity, but mainly metal. Such metal may be one or more materials selected from the group consisting of gold, silver, platinum, copper, nickel, chromium, aluminum, tungsten, titanium and palladium. It may be appropriately selected depending on the electrical and mechanical properties such as conductivity, ductility and conductivity of the metal.

The reason why the flexible substrate 100 of the flexible wiring structure according to the present invention has the concave-convex structure 101 is that the flexible substrate 100 is patterned on the substrate 100 according to an external stimulus of deformation, for example, stretching or bending. Since the wiring 110 may be stressed and the sheet resistance may change, this is to prevent such property degradation. In other words, in order to disperse the stress caused by the deformation of the flexible substrate 100, the conductive wiring 110 is stacked while covering the surface of the uneven structure 101 in close contact with the surface of the uneven structure 101 in which bending is made in the vertical direction of the surface of the flexible substrate 100. Done.

According to such a structure, when stress such as stretching or bending is applied, wiring reliability in the vertical direction as well as the wiring in the planar direction is distributed because the stress is distributed. Since the wiring in the vertical direction may be thinner than the wiring in the horizontal direction due to the difference in step coverage during deposition, wiring deposition of sufficient thickness is required. Usually, the wiring thickness of 200 nm or more does not cause a problem in the vertical wiring.

4 is a cross-sectional view taken along line A-A 'of the flexible wiring structure according to FIG. Referring to FIG. 4, (a) is a projection 101a formed on a substrate to form an uneven structure, and (b) is a depression 101b formed on a substrate to form an uneven structure. It can be seen that the conductive wirings 110 are stacked while being in close contact with the surfaces of the protrusions 101a and the recessed portions 101b.

According to the degree of deformation and the material of the substrate, the shape and specification of the uneven structure may vary. For example, the shape of the uneven structure may have any shape as long as it can disperse stress. At least one columnar or hemispherical protrusion 101a or depression 101b may be provided on the flexible substrate 100. Such uneven structures may be created directly on the flexible substrate or on a new layer of flexible material, such as a PDMS layer, stacked on the flexible substrate.

The uneven structure may be a periodic structure or a non-periodic structure having a predetermined interval.

It is preferable that the height and depth of the protrusion 101a or the depression 101b have a thickness of 10 nm to 1 μm. In addition, the adjacent distance between the protrusion 101a and the protrusion 101a or between the depression 101b and the depression 101b preferably has a thickness of 100 nm to 100 μm. In addition, it is preferable that the widths of the protrusions 101a and the depressions 101b have an adjacent distance x 0.1 to an adjacent distance x 0.9.

5 is a view showing the direction of a possible deformation of the flexible wiring structure according to the first embodiment of the present invention, where (a) is a plan view and (b) is A-A 'cross-sectional view.

Referring to this, the flexible wiring structure having the conductive wiring patterned on the flexible substrate on which the two-dimensional uneven structure is arranged can be stretched in any direction up, down, left and right with respect to the substrate surface, and as shown in (b), the horizontal It has a structure that can relieve stress not only in directional stretching but also in bending the substrate itself, that is, bending in a direction perpendicular to the substrate surface.

As described above, the flexible wiring structure uses a flexible substrate having a concave-convex structure and pattern the conductive wiring thereon, so that the conductive wiring can withstand deformation in various directions, so that the electrical performance is suitable for repeated use over a long period of time. Can be maintained.

Hereinafter, a preferred method of manufacturing the flexible wiring structure will be described in detail.

First, the uneven structure 101 is formed on the flexible substrate 100. In this case, the uneven structure 101 may be further stacked on another flexible material first on the flexible substrate 100 and then formed thereon. Such a method of forming the uneven structure may be suitably utilized, for example, after a lithography process using a photoresist, or an existing process including inkjet printing, imprinting, and the like.

Next, in patterning the conductive wiring in a desired shape on the flexible substrate on which the uneven structure is formed, the flexible wiring structure according to the first embodiment of the present invention is formed by laminating the conductive wire so as to cover and cover at least along the surface of the uneven structure. It can manufacture. At this time, as a method of forming the conductive wiring, a dry etching or a wet etching process may be used after electron beam deposition, thermal deposition, sputtering, deposition of wiring using electroplating, and patterning process using photoresist. Alternatively, direct printing of electrical wires is possible using printing processes such as nanoimprinting or inkjet printing.

Hereinafter, the flexible wiring structure according to the second embodiment of the present invention will be described in detail.

6 is a view showing a flexible wiring structure according to a second embodiment of the present invention. Referring to this, the flexible substrate 200; A conductive wiring 210 patterned on the flexible substrate 200; And at least one bridged connection line 230 patterned thereon along the conductive line 210 and protruding in the vertical direction of the flexible substrate 200.

Matters regarding the materials of the flexible substrate 200 and the conductive wiring 210 are the same as described above in the previous embodiment.

In this case, when the flexible substrate 200 is deformed by an external magnetic pole or the like, the connection wiring 230 is further present so that the stress is dispersed while deforming together. In addition, a free space 220 ′ is provided between the conductive wires 210 disposed under the connection wires 230, and each end portion of the connection wires 230 is in electrical contact with the conductive wires 210.

The connection wiring 230 having a bridge type having an empty free space 220 'at the bottom thereof is arranged according to the axial direction in which the device is stretched, and the conductive wiring 210 is broken according to the deformation of the device such as stretching or bending. The length margin is set so as not to increase or increase resistance, and acts like a spring to absorb the impact of deformation.

The distance between the adjacent connection wiring 230 bridge and the bridge can be variously determined according to the thickness of the substrate and the wiring used, the degree of deformation, etc., and generally has a range of 0.1 mm to 1 mm.

The height or width of the free space 220 'may also be variously determined according to the thickness of the substrate and the wiring and the degree of deformation, and generally has a range of 250 nm to 3 μm.

Therefore, the elastic wiring structure can maintain electrical properties such as sheet resistance by releasing stress caused by stretching in the bridge-lined direction and bending of the substrate in the vertical direction as shown in the arrow direction shown in FIG. 6.

Here, the connection wiring 230 is not limited as long as the material is well-electricity, but mainly metal is preferred. Such metal may be one or more materials selected from the group consisting of gold, silver, platinum, copper, nickel, chromium, aluminum, tungsten, titanium and palladium. It may be appropriately selected depending on the electrical and mechanical properties such as conductivity, ductility and conductivity of the metal. The type of material is not limited as long as it is in electrical contact with the conductive wiring 210 and does not adversely affect the electrical characteristics, and can be flexibly deformed with the deformation of the substrate, and is the same as the conductive wiring 210. It may be a material or a different material.

The preferred manufacturing method of such a flexible wiring structure will be described in detail as follows.

7 is a view illustrating a method of manufacturing a flexible wiring structure according to a second embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along line B-B 'of each step of the manufacturing method of FIG.

Referring to FIGS. 7 and 8, first, a conductive wiring 210 having a desired shape is patterned on the flexible substrate 200 (FIGS. 7 and 8 (a)).

Next, at least one protrusion structure 220 is formed on the conductive wiring 210 (FIGS. 7 and 8 (b)). The protruding structure 220 is finally removed by temporarily generating the connection wiring 230 to be coupled with the conductive wiring 210 in the form of a bridge in a later step.

The shape and size of the protruding structure 220 is not particularly limited and is formed along the conductive wire 210. As a material for forming the protruding structure 220, a material that can be easily printed on the conductive wiring 210 and easily removed in a subsequent process is preferable, and possible materials include PEDOT, PVP, PR, and the like. Can be.

As a method for forming at least one protrusion structure 220 on the conductive wiring 210, inkjet printing and screen printing may be used.

Then, each end portion is in electrical contact with the conductive wiring 210, and at least one connection wiring 230 is formed on the conductive wiring 210 so as to cover the surface of the projecting structure 220 (Fig. 7 and (c) of FIG. 8).

For example, when the silver (Ag) connection wiring is printed by the inkjet printing method, it may be formed with a thickness of about 250 nm to 300 nm and a length of 50 μm or more, respectively.

Subsequently, the connection structure 230 is removed and the connection wiring 230 is allowed to pass over the place where the protrusion structure 220 is removed so that the connection wiring 230 is free from the conductive wiring 210. By forming a tunnel or bridge type structure having a space 220 ', a flexible wiring structure is made (FIGS. 7 and 8 (d)).

The method of removing the protruding structure 220 varies depending on the type of the material, but there is a method of removing the protruding structure 220 by undercutting it in a solvent that does not affect the metal wiring while melting the material. For example, in the case of PEDOT which is a conductive polymer, It can be dissolved in and removed.

At this time, the height of the free space 220 'generated in the place where the projecting structure 220 was located is generally the same as the height of the projecting structure 220, the distance between the bridge ends of one connection wiring 230 is also projecting structure 220 Is determined by the width. That is, the shape and size of the connection wiring 230 are determined according to how the protrusion structure is patterned.

9 is a view showing a preferred embodiment of the flexible wiring structure according to the second embodiment of the present invention.

Referring to this, it is possible to implement a conductive wiring that can be stretched in any direction of a two-dimensional plane within a substrate.

Since the conventional method is a method of forming a wiring structure by stretching the substrate in advance, it is possible to form only a one-dimensional spring structure, and there is a problem that it is difficult to predict peaks or periods. It can be made to have a spring structure in the direction, and the peak and period can be adjusted in various ways depending on the projecting structure when the connecting wiring in the form of a bridge. In addition, the bridge is built in the vertical direction to withstand the bending of the substrate.

Hereinafter, the flexible wiring structure according to the third embodiment of the present invention will be described in detail.

10 is a view showing a flexible wiring structure according to a third embodiment of the present invention. Referring to this, the flexible substrate 300; And a conductive wiring 330 patterned on the flexible substrate 300 and having an uneven structure curved in a direction perpendicular to the substrate surface along the flexible substrate 300 and having an electrical contact point on the flexible substrate 300. It shows a flexible wiring structure provided.

Matters regarding the materials of the flexible substrate 300 and the conductive wiring 330 are the same as described above in the previous embodiment.

However, the conductive wire 330 has a margin of its own length, not by the connection wiring, unlike the second embodiment, and adjacent to the stress so that the stress can be dispersed while deforming together with the deformation of the flexible substrate 300. There is a clearance 320 'between the electrical contacts.

The conductive wire 330 having such a long margin has a length margin so that the conductive wire 330 is not broken or the resistance increases due to the deformation of the device such as stretching or bending. Can absorb.

The spacing between the concave-convex structures (bridges) of the adjacent conductive wires 330 may be variously determined depending on the thickness of the substrate and the wiring used, the degree of deformation, and the like, and may generally range from 0.1 mm to 1 mm.

The height or width of the clearance 320 'may also be determined in various ways depending on the thickness of the substrate and the wiring and the degree of deformation, and generally has a range of 250 nm to 1 μm.

In addition, the uneven structure may be formed periodically or aperiodically.

Hereinafter, a preferred method of manufacturing the flexible wiring structure will be described in detail.

11 is a view showing a method of manufacturing a flexible wiring structure according to a third embodiment of the present invention.

Referring to this, first, at least one protrusion structure 320 is formed on the flexible substrate 300 (FIG. 11A).

The protruding structure 320 is finally removed as temporarily created for use in making the uneven structure in the vertical direction of the substrate surface when the conductive wire 330 is bonded to the substrate in a later step.

With regard to the material, role of the protruding structure 320 and the method of the subsequent removal and the like as described above in the previous embodiment.

Next, a conductive wiring 330 having a desired structure is patterned to cover the surface of the projecting structure and to be formed on the flexible substrate 300 (FIG. 11B). In this case, a method such as inkjet printing or screen printing may also be used as described above.

Next, by removing the protrusion 320, a bridge of the conductive wiring 330 is formed at each position where the protrusion 320 is removed, and has an electrical contact point with the substrate, and has a margin equal to the size of the protrusion 320. The flexible wiring structure is fabricated by allowing the space 320 'to be formed between the bridge of the conductive wiring 330 and the flexible substrate 300 below it (FIG. 11C).

As a result, the height of the free space 320 'generated at the place where the protruding structure 320 is located is generally the same as the height of the protruding structure 320, and the adjacent electrical contact point between the conductive wiring 330 and the flexible substrate 300 is present. The distance between the two is also determined by the width of the protrusion 320. That is, the shape and size of the concave-convex structure is determined according to how the protrusion structure 320 is patterned.

According to the above manufacturing method, unlike the case of the second embodiment, it is possible to manufacture by one conductive wiring patterning without the additional process of re-forming the connection wiring on the patterned conductive wiring.

In addition, the flexible wiring structure manufactured according to the above-described manufacturing method may implement two-dimensional flexible wiring in the biaxial direction in addition to the uniaxial direction as in the case of the second embodiment.

In the foregoing description, a preferred embodiment according to the present invention has been described with reference to the drawings, but this is only an example, and those skilled in the art may understand that various modifications and equivalent other embodiments are possible. There will be. Therefore, the protection scope of the present invention should be defined by the appended claims.

1 is a view showing a step of manufacturing a flexible wiring structure according to the prior art.

2 is a view showing a step of manufacturing a flexible wiring structure according to the prior art.

3 is a view showing a flexible wiring structure according to a first embodiment of the present invention, (a) shows a two-dimensional uneven structure pattern, and (b) shows a one-dimensional uneven structure pattern.

4 is a cross-sectional view taken along line A-A 'of the flexible wiring structure according to FIG.

5 is a view showing the direction of a possible deformation of the flexible wiring structure according to the first embodiment of the present invention, where (a) is a plan view and (b) is A-A 'cross-sectional view.

6 is a view showing a flexible wiring structure according to a second embodiment of the present invention.

7 is a view showing a method of manufacturing a flexible wiring structure according to a second embodiment of the present invention.

8 is a cross-sectional view taken along line B-B 'of each step of the manufacturing method of FIG.

9 is a view showing a preferred embodiment of the flexible wiring structure according to the second embodiment of the present invention.

10 is a view showing a flexible wiring structure according to a third embodiment of the present invention.

11 is a view showing a method of manufacturing a flexible wiring structure according to a third embodiment of the present invention.

Claims (23)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete Flexible substrates; Conductive wiring patterned on the flexible substrate; And at least one connecting wiring patterned thereon along the conductive wiring and protruding in the vertical direction of the flexible substrate. The connection wiring has a clearance between the conductive wiring located below the connection wiring so that the stress can be dispersed while deforming together with the deformation of the flexible substrate, and each end of the connection wiring is in electrical contact with the conductive wiring. Flexible wiring structure. The method of claim 15, The connecting wiring is a flexible wiring structure, characterized in that made of the same or different material than the conductive wiring. Patterning conductive wiring of a desired type on the flexible substrate; Forming at least one protrusion structure on the conductive wiring; Forming at least one connection wiring on the conductive wiring such that each end portion is in electrical contact with the conductive wiring and covers the surface of the protruding structure; And Removing the protruding structure so that the connecting line has a bridge structure by passing the upper portion of the place where the protruding structure is removed, thereby forming a free space between the connecting line and the conductive line; Method of manufacturing a flexible wiring structure comprising a. Flexible substrates; And a conductive wiring patterned on the flexible substrate, the conductive wiring having an uneven structure curved in a vertical direction along the flexible substrate and having an electrical contact point on the flexible substrate. The flexible wiring structure, characterized in that it has a free space between the adjacent electrical contact points so that the stress can be distributed while deforming together with the deformation of the flexible substrate. Forming at least one protrusion on the flexible substrate; Patterning the conductive wiring of a desired structure across the surface of the projecting structure and being formed on the flexible substrate; And By removing the protruding structure, the bridge of the conductive wire is formed at each position where the protruding structure is removed, and the electrical contact point is provided with the flexible substrate, and the free space equal to the size of the protruding structure is defined by the bridge of the conductive wire. Forming between lower flexible substrates; Method of manufacturing a flexible wiring structure comprising a. The method of claim 17 or 19, The projecting structure is a method of manufacturing a flexible wiring structure, characterized in that formed periodically or aperiodic. The method of claim 17 or 19, The protruding structure is a manufacturing method of the flexible wiring structure, characterized in that consisting of PEDOT, PVP, or PR. The method of claim 17 or 19, The protruding structure is a manufacturing method of the flexible wiring structure, characterized in that formed by inkjet printing or screen printing. The method of claim 17 or 19, Removing the protruding structure is a method of manufacturing a flexible wiring structure, characterized in that by removing the undercut by dipping in a solvent that does not affect the metal wiring.

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