Patent Application
20150189741
This application claims the priority of Korean Patent Application No. 10-2013-0166838 filed on Dec. 30, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method of forming a stretchable substrate, a stretchable substrate, and an electronic device having a stretchable substrate.
2. Description of the Related Art
Recently, stretchable electronic devices have been highlighted. Those electronic devices can freely bend and curve in comparison to existing electronic devices, so an interest in the electronic devices have been increased in the fields of display and bio engineering. In the related art, since the stretchable electronic devices are formed on stretchable substrates, they are extended or compressed with extension and compression of the substrates. This is because when a physical force such as tensile, buckling or torsion force is applied to a general elastic body from the outside, the elastic body uniformly and isotropically deforms throughout the entire section.
When an external force is applied to a stretchable substrate, the stretchable substrate extends in the direction of the external force. In general, electronic circuits or wirings formed on substrates have different Young's modulus from that of the substrates, so the degree of strain of the electronic circuits or wirings due to an external force is different from that of the substrates. For example, when an electrical wiring having low stretchability is formed on a substrate having higher stretchability than the wirings, and then a tensile force is applied to the substrate, the electrical wiring that is lower in stretchability than the substrate cannot extend as much as the substrate and stress is exerted in the electrical wiring, so the electric wiring is physically damaged, such as cracking. Accordingly, an electronic or an electric device electrically connected through the electrical wiring cannot stably operate. This phenomenon may occur even when not only the electrical wiring, but another electronic device having stretchability different from that of the stretchable substrate is formed on the substrate and then an external force is applied to the substrate, so it is difficult to guarantee stable operation of the electronic devices on the stretchable substrate.
An aspect of the present invention provides a method of forming a stretchable substrate that can reduce physical stress in an element or a wiring, even if an external force is applied. Another aspect of the present invention provides an electronic device that stably operates even under an external force, because an element or a wiring thereon is less physically damaged, even if an external force is applied.
According to an aspect of the present invention, there is provided a stretchable substrate including: a substrate having first Young's modulus and stretchability; and strain control patterns having second Young's modulus and arranged on the substrate, in which strain due to an external force depends on arrangement of the strain control patterns.
According to another aspect of the present invention, there is provided a method of forming a stretchable substrate that includes: forming strain control patterns on a stretchable support substrate; and covering the strain control patterns on the stretchable support substrate with a stretchable member.
According to another aspect of the present invention, there is provided an electronic device including: a stretchable substrate; and an electronic circuit unit on the stretchable substrate, in which strain control patterns are disposed inside the stretchable substrate.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
The description of the present invention is just examples for structural and functional illustration, and thus the scope of the present invention should not be construed as being limited by these examples. That is, since the present invention may be variously modified and have several exemplary embodiments, the scope of the present invention should be understood as including equivalents by which the spirit of the present invention can be achieved.
The terms used herein should be understood as follows.
Terms, such as “first” and “second”, are for discriminating one component from another component, but the scope is not limited to the terms. For example, the first component may be named the second component and the second component may also be similarly named the first component.
It is to be understood that when one element is referred to as being “on” or “above” another element, it may be directly on another element, but other elements may be disposed between them. On the other hand, it is to be understood that when one element is referred to as being “in contact with” another element, it may be connected to another element without other elements therebetween. Further, other expressions describing the relationships of components, that is, “interposed” and “directly interposed, “between” and “directly between”, or “close to” and “directly close to” should be understood in the same way.
Singular forms are intended to include plural forms unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” or “have” as used in this specification specify the presence of stated features, steps, operations, components, parts, or a combination thereof, but do not preclude the presence or addition of one or more other features, numerals, steps, operations, components, parts, or a combination thereof.
The steps happen in different ways from the order described herein unless the context clearly indicates the order otherwise. That is, the steps may be generated in the order described and substantially simultaneously, but they may be performed in reverse direction.
In the drawings referred to herein for describing exemplary embodiments of the present invention, the size, height, thickness, and the like, may be intentionally exaggerated and not absolutely enlarged or reduced in accordance with scales. Further, some components may be intentionally reduced and some other components may be intentionally enlarged.
Unless defined otherwise, it is to be understood that all the terms used herein including technical and scientific terms have the same meaning as those as understood by those who are skilled in the art. It should be understood that the terms defined by dictionaries must be identical with the meanings within the context of the related art, and they should not be ideally or excessively formally defined unless the context clearly dictate otherwise.
A method of forming a stretchable substrate according to an embodiment of the present invention and a stretchable substrate will be described with reference to the accompanying drawings.
The strain control pattern is formed on the stretchable support substrate 110. In an embodiment, the strain control pattern may be formed by putting a polymer material 210 such as ETPTA (ethoxylated trimethylolpropane trizcrylate), PMMA (poly methyl methacrylate), polystyrene, ecoflex, and hydrogel onto the stretchable support substrate 110, and then curing the polymer material. For example, the polymer material may be printed on the stretchable support substrate. In order to print the polymer material 210, transfer printing that puts a polymer material to be formed onto a mold 200a and then printing it onto a stretchable support substrate, as illustrated in
As another embodiment, the strain control pattern may be formed by photo lithography. For example, the strain control pattern is formed by forming a polymer material layer on a stretchable support substrate, forming a mask pattern, and then etching them. Alternatively, the strain control pattern may be formed by forming a mask pattern on a stretchable support substrate, forming and curing a polymer material layer and then removing the cured polymer on the mask pattern except the strain control pattern formed on the stretchable support substrate.
The strain control pattern 200 is formed by curing the polymer material 210 on the stretchable support substrate. Referring to
The Young's modulus of the strain control pattern 200 is different from that of the stretchable support substrate. The Young's modulus of a strain control pattern has only to be different from that of a stretchable support substrate, but is not necessarily be larger or smaller than that of a stretchable support substrate.
A plurality of strain control patterns 200 on the stretchable support substrate is covered with a stretchable member 120. Referring to
In another embodiment, when the stretchable substrate 100 repeatedly bends in any one direction, any one of the stretchable support substrate 110 and the stretchable member 120 extends further than the other one. Accordingly, delamination may be easier by using the same material for the stretchable support substrate 110 and the stretchable member 120. In this case, any one of the stretchable support substrate 110 and the stretchable member 120 may be made of a material having less Young's modulus and larger elasticity.
An electronic circuit unit 300 is formed on the stretchable substrate 100. The electronic circuit unit 300 includes active elements such as a transistor and an integrated circuit, passive elements such as a resistor and a capacitor, and various sensors and/or conductive wirings, and performs predetermined functions. Referring to
According to another embodiment of the present invention, when a strain control pattern having Young's modulus smaller than those of the stretchable support substrate 110 and the stretchable member 120 is disposed inside a stretchable substrate and an external force (tensile strain) is applied to the stretchable substrate, it can be seen, as illustrated in
When an external force is applied to a stretchable substrate with a strain control pattern therein, strain (stress) due to the external force concentrates on the strain control pattern or periphery of the strain control pattern, and it decreases as distance from the strain control pattern increases, such that the strain due to an tensile force applied to the stretchable substrate can be adjusted to be anisotropic in accordance with the arrangement of strain control patterns. For example, as illustrated in
As another example, strain control patterns may be arranged in a lattice shape, as illustrated in
The simulation results of an embodiment of the present invention are described hereafter with reference to the accompanying drawings. In simulation on an embodiment of the present invention to be described hereafter, stretchable support substrate and stretchable member were made of PDMS and strain control patterns were made of ETPTA.
Further, in simulation on another embodiment of the present invention, stretchable support substrate and stretchable member were made of PDMS and strain control patterns were made of hydrogel.
In the simulation of the embodiments of the present invention, the strain control patterns were arranged in the shape of a lattice, as illustrated in
Referring to
In
In
Referring to
In
In
As set forth above, according to the stretchable substrate and the electronic device of exemplary embodiments of the invention, even if the substrate is deformed due to an external force, it is possible to adjust stress that is exerted in objects such as an electronic element, using the strain control patterns. Further, according to the stretchable substrate and the electronic device of the present invention, even if the substrate bends or extends due to an external force, the objects such as an electronic element on the substrate can operate stably.
According to the method of forming a stretchable substrate of the present invention, it is possible the manufacture a stretchable substrate having the technological effects described above.
While the present invention has been illustrated and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2013-0166838 | Dec 2013 | KR | national |
