Stretchable electrode and manufacturing method thereof

Abstract

The present invention relates to a stretchable electrode and a manufacturing method thereof. Specifically, according to one embodiment of the present invention, a stretchable electrode may be provided, the stretchable electrode comprising: a substrate; a conductive wire laminated on the upper portion of the substrate; and an electrically conductive metal layer laminated on the upper portion of the conductive wire.

Description

Flexible electrode and method for manufacturing the same

[0001] The present invention relates to a flexible electrode and a method for manufacturing the same.

[0002] As the applications of electronic devices expand, demand is growing for flexible electronic devices that can overcome the limitations of conventional electronic devices placed on rigid substrates. Products utilizing these flexible electronic devices include flexible displays, smart clothing, smartwatches, and vital sensors.

[0003] To realize flexible electronic devices, the components that make up the flexible electronic device must be able to maintain their electrical function even when physically deformed by external stress. Among the components that make up these flexible electronic devices, the electrodes must be able to maintain electrical conductivity even when subjected to mechanical deformation (e.g., folding, bending, stretching). To this end, technologies for forming stretchable electrodes using conductive polymers and conductive nanomaterials are being researched. However, conductive polymers have low conductivity, making them unsuitable for current-driven electronic devices. While conductive nanomaterials have high conductivity, they can crack even under small stresses, making them difficult to use as components of stretchable electrodes.

[0004] The embodiments of the present invention were invented against the background described above, and are intended to provide a flexible electrode capable of simultaneously satisfying high electrical conductivity and elasticity by using liquid metal as an electrically conductive metal layer, and a method for manufacturing the same.

[0005] According to one aspect of the present invention, a flexible electrode may include: a substrate; a conductive wire laminated on an upper portion of the substrate; and an electrically conductive metal layer laminated on an upper portion of the conductive wire.

[0006] In one embodiment, the flexible electrode may further include an interfacial metal layer laminated between the substrate and the electrically conductive metal layer such that the conductive wire is impregnated therein.

[0007] In one embodiment, the interfacial metal layer may be formed of a metal having a lower ionization tendency than the electrically conductive metal layer.

[0008] In one embodiment, the conductive wire may be impregnated so as to be introduced into the interior of the interfacial metal layer, so that an interfacial metal layer is formed on top of the conductive wire, and the electrically conductive metal layer may be laminated on top of the interfacial metal layer.

[0009] In one embodiment, the conductive wire may be laminated on the substrate by spraying, the interfacial metal layer may be laminated on the conductive wire by thermal deposition, and the electrically conductive metal layer may be laminated on the interfacial metal layer by spraying.

[0010] In one embodiment, each of the conductive wire, the electrically conductive metal layer, and the interface metal layer may be formed of any one of gold, silver, copper, and aluminum.

[0011] In one embodiment, the conductive wire, the electrically conductive metal layer, and the interface metal layer may be formed of different metals or the same metal.

[0012] In one embodiment, at least two selected from the conductive wire, the electrically conductive metal layer, and the interface metal layer may be formed of the same metal, and the remaining one may be formed of a metal different from the selected two.

[0013] In one embodiment, the laminated thickness of the interfacial metal layer may be 10 nm or less.

[0014] In addition, in another embodiment of the present invention, a method for manufacturing a flexible electrode may include: (a) a step of providing a substrate; (b) a step of laminating a conductive wire on the upper portion of the substrate by a spray method; (c) a step of laminating an interface metal layer on the conductive wire by a thermal deposition method; and (d) a step of laminating an electrically conductive metal layer on the upper portion of the interface metal layer by a spray method.

[0015] According to embodiments of the present invention, by using liquid metal as an electrically conductive metal layer, there is an effect of simultaneously satisfying high electrical conductivity and elasticity.

[0016] FIG. 1 is a cross-sectional view of a flexible electrode according to one embodiment of the present invention.

[0017] Figure 2 is a drawing showing a state in which conductive wires are laminated on the upper part of the substrate of Figure 1.

[0018] Figure 3 is a drawing showing a state in which an interface metal layer is laminated on the conductive wire of Figure 2.

[0019] Figure 4 is an enlarged view showing the state in which the interface metal layer in Figure 1 has been removed.

[0020] Figure 5 is an enlarged view of Figure 1.

[0021] Figure 6 is a graph comparing the charge resistance of Figure 1 with other electrodes.

[0022] Figure 7 is a graph comparing the carrier concentration of Figure 1 with other electrodes.

[0023] Hereinafter, specific embodiments for implementing the technical idea of ​​the present invention will be described in detail with reference to the drawings.

[0024] In addition, when explaining the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description is omitted.

[0025] Additionally, when it is said that a component is 'supported' or 'transmitted' to another component, it should be understood that it may be supported or transmitted directly to that other component, but there may also be other components in between.

[0026] The terminology used herein is intended solely to describe specific embodiments and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0027] Additionally, please note that the terms "upper side," "lower side," and "side" in this specification are based on the illustrations in the drawings and may be expressed differently if the orientation of the subject changes. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted, and the sizes of each component do not fully reflect the actual size.

[0028] Additionally, terms that include ordinal numbers, such as "first," "second," etc., may be used to describe various components, but these components are not limited by such terms. These terms are used solely to distinguish one component from another.

[0029] The term "comprising" as used in the specification means specifying a particular characteristic, region, integer, step, operation, element and / or component, but does not exclude the presence or addition of other particular characteristics, regions, integers, steps, operations, elements, components and / or groups.

[0030] Hereinafter, a specific configuration of a flexible electrode according to one embodiment of the present invention will be described with reference to the drawings.

[0031] Referring to FIG. 1, a stretchable electrode (100) according to one embodiment of the present invention may be provided in a flexible electronic device to provide a path through which current flows. This stretchable electrode (100) may include a substrate (110), a conductive wire (120), an interface metal layer (130), and an electrically conductive metal layer (140).

[0032] The substrate (110) can support the components of the stretchable electrode (100). In other words, a lamination space can be provided on the upper surface of the substrate (110) in which a conductive wire (120), an interface metal layer (130), and an electrically conductive metal layer (140) can be laminated. The substrate (110) can be provided as a flexible substrate rather than a rigid substrate so that it can be used in a flexible electronic device. For example, the substrate (110) can be provided as a flexible printed circuit board (FPCB) or the like to impart elasticity to the stretchable electrode (100).

[0033] The conductive wire (120) may be a fine wire made of a material capable of effectively transmitting electricity and having a thickness in the nanometer scale. This conductive wire (120) may be laminated on the upper part of the substrate (110). The conductive wire (120) may be laminated by spraying and coating the upper part of the substrate (110) using shadow masking. For example, the substrate (110) may be placed on a 120°C hot plate, and the conductive wire (120) may be applied by spraying on the upper part of the substrate (110). The conductive wire (120) may be sprayed by a separate spray gun, and the spraying pressure of the conductive wire (120) may be 80 MPa. In this way, the conductive wire (120) applied on the upper part of the substrate (110) can be coated on the upper part of the substrate (110) by being cured at a temperature of 100°C to 180°C for about 10 minutes. The temperature for curing the conductive wire (120) may be 120°C. The conductive wire (120) may be formed of a metal, and in particular, may be formed of one metal selected from gold, silver, copper, and aluminum. The conductive wire (120) may be formed of a different metal from or the same metal as the interfacial metal layer (130) and the electrically conductive metal layer (140). Additionally, the conductive wire (120) may be formed of the same metal as one selected from among the interface metal layer (130) and the electrically conductive metal layer (140), and the unselected one from among the interface metal layer (130) and the electrically conductive metal layer (140) may be formed of a metal different from the conductive wire (120).

[0034] The interfacial metal layer (130) may be laminated on the conductive wire (120) so that the conductive wire (120) is impregnated therein. In other words, the interfacial metal layer (130) may be laminated between the substrate (110) and the electrically conductive metal layer (140). This interfacial metal layer (130) may be laminated on the conductive wire (120) by thermal deposition. For example, the interfacial metal layer (130) may be laminated at a pressure of 10 -7torr vacuum state, it can be thermally deposited on the conductive wire (120). Since the thermal deposition of the interface metal layer (130) is performed in a vacuum state, a separate gas mixture may not be mixed. When the interface metal layer (130) is deposited on the conductive wire (120) by the thermal deposition method, the interface metal layer (130) can be deposited so as to fill the empty space of the conductive wire (120). In other words, the interface metal layer (130) can be deposited so as to fill the empty space of the conductive wire (120), and the conductive wire (120) can be impregnated so as to be completely inserted into the interior of the interface metal layer (130). Therefore, the interface metal layer (130) can be formed in the empty space of the conductive wire (120) and on the upper portion of the conductive wire (120). This interfacial metal layer (130) may be formed of a metal, and in particular, may be formed of one metal selected from among gold, silver, copper, and aluminum. This interfacial metal layer (130) may be formed of a different metal from or the same metal as the conductive wire (120) and the electrically conductive metal layer (140). In addition, the interfacial metal layer (130) may be formed of the same metal as one selected from the conductive wire (120) and the electrically conductive metal layer (140), and one of the conductive wires (120) and the electrically conductive metal layer (140) that is not selected may be formed of a metal different from the interfacial metal layer (130). In addition, the interfacial metal layer (130) may be formed of a metal having a lower ionization tendency than the electrically conductive metal layer (140). For example, when the electrically conductive metal layer (140) is formed of silver, the interfacial metal layer (130) may be formed of copper having a lower ionization tendency than silver. If the interfacial metal layer (130) is formed of a metal having a higher ionization tendency than the electrically conductive metal layer (140), the electrically conductive metal layer (140) may be oxidized due to the liquid metal. The laminated thickness of the interfacial metal layer (130) may be 10 nm or less. If the laminated thickness of the interfacial metal layer (130) becomes excessively thick, cracks in the interfacial metal layer (130) generated during tension may become excessively large, making it difficult to secure elasticity.

[0035] The electrically conductive metal layer (140) may be laminated on top of the interfacial metal layer (130). This electrically conductive metal layer (140) may be laminated by spraying liquid metal onto the upper portion of the interfacial metal layer (130) through shadow masking. For example, the electrically conductive metal layer (140) may be applied by spraying onto the upper portion of the interfacial metal layer (130). The electrically conductive metal layer (140) is formed of liquid metal, and the liquid metal may have a viscosity of 0.0024 pa-s at. The liquid metal may be sprayed by a separate spray gun, and the spraying pressure of the liquid metal may be 80 MPa. The electrically conductive metal layer (140) may be formed of a metal, and in particular, may be formed of one liquid metal selected from Galinstan and EulnGa. This electrically conductive metal layer (140) may be formed of a different metal from or the same metal as the conductive wire (120) and the interface metal layer (130). In addition, the electrically conductive metal layer (140) may be formed of the same metal as one selected from the conductive wire (120) and the interface metal layer (130), and one of the conductive wires (120) and the interface metal layer (130) that is not selected may be formed of a different metal from the conductive wire (120). This electrically conductive metal layer (140) may be formed in an embossed shape on the upper surface of the interface metal layer (130) by spraying liquid metal.

[0036] Hereinafter, with reference to FIGS. 1 to 3, a method for manufacturing a flexible electrode (100) according to one embodiment of the present invention will be described.

[0037] Referring to FIG. 2, a substrate (110) is provided, and a conductive wire (120) may be laminated on the upper portion of the substrate (110). The conductive wire (120) may be formed by spraying a metal onto the upper portion of the substrate (110) and laminating it. For example, the substrate (110) may be placed on a 120°C hot plate, and silver nanowires, which are conductive wires (120), may be sprayed onto the upper portion of the substrate (110) and applied thereto. The silver nanowires may be spray-coated using 2 ml of a solution in which 1 ml of the original solution is dispersed in 15 ml of 1 Pa. The conductive wire (120) may be sprayed by a separate spray gun, and the spraying pressure of the conductive wire (120) may be 80 MPa. In this way, the conductive wire (120) applied to the upper portion of the substrate (110) can be coated on the upper portion of the substrate (110) by being cured at a temperature of 100°C to 180°C for about 10 minutes. The temperature for curing the conductive wire (120) can be 120°C.

[0038] Referring to FIG. 3, when a conductive wire (120) is laminated on the upper portion of a substrate (110), an interface metal layer (130) may be laminated on the conductive wire (120). The interface metal layer (130) may be formed by thermal deposition of a metal on the conductive wire (120). For example, the interface metal layer (130) may be formed when the pressure is 10 -7 It can be thermally deposited on the conductive wire (120) in a vacuum state of 10 torr. This interface metal layer (130) can fill the empty space of the conductive wire (120) through thermal deposition, thereby completely impregnating the conductive wire (120) into the interior of the interface metal layer (130).

[0039] Referring to Fig. 1, when an interface metal layer (130) is laminated on a conductive wire (120), an electrically conductive metal layer (140) can be laminated on top of the interface metal layer (130). The electrically conductive metal layer (140) can be formed by spraying liquid metal onto the interface metal layer (130) and laminating it. For example, the electrically conductive metal layer (140) can be applied by spraying it onto the interface metal layer (130). The electrically conductive metal layer (140) is formed of liquid metal, and the liquid metal can have a viscosity of 0.0024 pa-s at. The liquid metal can be sprayed by a separate spray gun, and the spraying pressure of the liquid metal can be 80 MPa.

[0040] Hereinafter, with reference to FIGS. 4 to 7, the operation and effect of the elastic electrode (100) according to one embodiment of the present invention will be described.

[0041] Fig. 4 shows a state in which an electrically conductive metal layer (140) is laminated on a conductive wire (120) without an interface metal layer (130) being laminated. Since there are many empty spaces in the conductive wire (120), the electrically conductive metal layer (140) may not cover the entire conductive wire (120) and may be sparsely laminated on top of the conductive wire (120).

[0042] On the other hand, FIG. 5 shows a state in which an electrically conductive metal layer (140) is laminated on top of an interfacial metal layer (130). Since the upper portion of the interfacial metal layer (130) is formed as a flat surface, the electrically conductive metal layer (140) can be laminated to cover almost the entirety of the interfacial metal layer (130). In other words, despite the surface tension of the electrically conductive metal layer (140) formed of liquid metal, the electrically conductive metal layer (140) can be laminated to cover almost the entirety of the interfacial metal layer (130).

[0043] Figure 6 is a graph comparing the charge resistance of a flexible electrode (100) according to one embodiment of the present invention with other electrodes. It is important for the flexible electrode (100) to maintain electrical conductivity in the horizontal direction, but it is also important for charge to move smoothly in the vertical direction.

[0044] In the case of AgNW-Ag-LM in which the conductive wire (120) and the interface metal layer (130) of the flexible electrode (100) are formed of silver, and an electrically conductive metal layer (140) made of liquid metal is laminated on top of the interface metal layer (130), the charge resistance can be stably maintained low even at a higher strain than AgNW formed only of silver nanowires, AgNW-Ag in which silver is laminated on top of silver nanowires, and AgNW-LM in which liquid metal is laminated on top of silver nanowires.

[0045] In addition, referring to FIG. 8, in the case of AgNW-Ag-LM, a higher carrier concentration can be maintained than AgNW, AgNW-Ag, and AgNW-LM. When the carrier concentration is high, it means that the amount of electrons that carry charges for electrical conduction is high, so the stretchable electrode (100) according to one embodiment of the present invention can have higher electrical conductivity than electrodes made of other materials. In addition, since the characteristics of the device can be secured only when the charge transfer is smooth, the carrier concentration in the electrode in the electronic device must be high in order to exhibit characteristics that can replace the metal thin film used in the existing rigid device.

[0046] The flexible electrode (100) according to one embodiment of the present invention as described above has the effect of satisfying high electrical conductivity and elasticity at the same time by laminating an interface metal layer (130) on a conductive wire (120) to completely impregnate the conductive wire (120) and laminating an electrically conductive metal layer (140) formed of liquid metal on top of the interface metal layer (130).

[0047] Although the embodiments of the present invention have been described as specific embodiments, these are merely examples, and the present invention is not limited thereto, but should be construed to have the broadest scope in accordance with the technical concepts disclosed in this specification. Those skilled in the art may combine / substitute the disclosed embodiments to implement patterns of shapes not specified, but this also does not depart from the scope of the present invention. In addition, those skilled in the art may easily modify or alter the disclosed embodiments based on this specification, and it is clear that such modifications or alterations also fall within the scope of the present invention.

[0048] 100: Flexible electrode 110: Substrate

[0049] 120: Conductive wire 130: Interfacial metal layer

[0050] 140: Electrically conductive metal layer

Claims

1. Substrate; Conductive wires laminated on the upper part of the substrate; and Including an electrically conductive metal layer laminated on top of the conductive wire, Flexible electrode.

2. In paragraph 1, Further comprising an interface metal layer laminated between the substrate and the electrically conductive metal layer so that the conductive wire is impregnated therein. Flexible electrode.

3. In paragraph 2, The above interfacial metal layer is formed of a metal having a lower ionization tendency than the electrically conductive metal layer. Flexible electrode.

4. In paragraph 2, The conductive wire is impregnated so as to be introduced into the interior of the interface metal layer, and an interface metal layer is formed on top of the conductive wire. The above conductive metal layer is laminated on top of the interface metal layer, Flexible electrode.

5. In paragraph 2, The above conductive wire is laminated on the substrate by spraying, The above interfacial metal layer is laminated on the conductive wire by thermal deposition, The above conductive metal layer is laminated on the interface metal layer by spraying. Flexible electrode.

6. In paragraph 2, The conductive wire, the electrically conductive metal layer, and the interface metal layer are each formed of one of gold, silver, copper, and aluminum. Flexible electrode.

7. In paragraph 6, The conductive wire, the electrically conductive metal layer, and the interface metal layer are formed of different metals or the same metal. Flexible electrode.

8. In paragraph 6, At least two selected from the conductive wire, the electrically conductive metal layer and the interface metal layer are formed of the same metal, and the remaining one is formed of a metal different from the selected two. Flexible electrode.

9. In paragraph 2, The laminated thickness of the above interfacial metal layer is 10 nm or less. Flexible electrode. 10.(a) The stage where the substrate is prepared (b) a step of laminating a conductive wire on the upper part of the substrate by spraying; (c) a step of depositing an interface metal layer on the conductive wire by thermal deposition; and (d) a step of depositing an electrically conductive metal layer on top of the interfacial metal layer by spraying, Method for manufacturing a flexible electrode.

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