Anisotropic conductive elastic material, method for producing the same, and elastic electronic element including the same

Abstract

The present invention relates to a stretchable anisotropic conductive film, a method for manufacturing the same, and a stretchable electronic device including the same. The stretchable anisotropic conductive film according to an embodiment of the present invention includes a patterned stretchable polymer; and a liquid metal filled in a patterned portion of the stretchable polymer.

Description

Technical Field

[0001] The present invention relates to a stretchable anisotropic conductive film, a method for manufacturing the same, and a stretchable electronic device including the same.

Background Art

[0002] With the extensive research on stretchable electronic devices highly utilized in fields such as electronic skin and healthcare, electrical bonding for stably connecting stretchable elements and circuits has also become important. Further, for electrical connection between fine elements and circuits, an anisotropic conductive film (ACF) having a highly regular arrangement is essential.

[0003] However, conventional ACFs have limitations in that the connection becomes unstable during stretching due to the difference in elastic modulus between element components, or there are limitations in the regular arrangement of fine intervals or large-area formation.

[0004] In the case of conventional ACFs, the solder balls or microparticles responsible for conductivity are hard. When used as a stretchable anisotropic conductive film (S-ACF), only the stretchable polymer stretches during tension, and the conductive balls do not stretch, resulting in problems such as the conductive balls being detached from the film or the electrical connection being broken.

[0005] Also, there are limitations in that it has low resolution and reliability due to a random arrangement of conductive particles, and only the portion pressed by the protruding electrode has anisotropic conductivity.

[0006] The background art described above is what the inventor retained or acquired in the process of deriving the disclosure of this specification, and it cannot necessarily be said to be publicly known technology publicly disclosed to the general public before this application.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention is for solving the above-described problems, and an object of the present invention is to provide a stretchable anisotropic conductive film having high stretchability and excellent conductivity over a large area, a method for manufacturing the same, and a stretchable electronic device including the same.

[0008] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those having ordinary knowledge in the art from the following description.

Means for Solving the Problems

[0009] The stretchable anisotropic conductive film according to an embodiment of the present invention includes a patterned stretchable polymer and a liquid metal filled in the patterned portion of the stretchable polymer.

[0010] In one embodiment, the liquid metal can be electrically conducted to both surfaces of the anisotropic conductive film.

[0011] The liquid metal can include at least one selected from the group consisting of gallium (Ga), indium (In), tin (Sn), mercury (Hg), lead (Pb), bismuth (Bi), cadmium (Cd), eutectic gallium-indium alloy (EGaIn), gallium-indium-tin eutectic alloy (Galinstan), gallium-indium (Ga / In), gallium / lead (Ga / Pb), gallium / cadmium (Ga / Cd), gallium / zinc (Ga / Zn), gallium / tin (Ga / Sn), gallium / bismuth (Ga / Bi), gallium / thallium (Ga / Tl), tin / silver (Sn / Ag), tin / gold (Sn / Au), tin / copper (Sn / Cu), tin / nickel (Sn / Ni), lead / antimony (Pb / Sb), lead / gold (Pb / Au), and lead / cadmium (Pb / Cd).

[0012] In one embodiment, the liquid metal may be 10% by weight to 80% by weight of the stretchable anisotropic conductive film.

[0013] In one embodiment, it may further include solid particles dispersed in the liquid metal.

[0014] In one embodiment, the solid particles may further include at least one selected from the group consisting of metal particles, metal oxide particles, and semiconductor oxide particles.

[0015] In one embodiment, the solid particles may include a core-shell structure.

[0016] In one embodiment, the metal particles may include at least one selected from the group consisting of copper (Cu), gold (Au), platinum (Pt), silver (Ag), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), chromium (Cr), tungsten (W), molybdenum (Mo), and titanium (Ti).

[0017] In one embodiment, the metal oxide particles or semiconductor oxide particles are SiO 2 , Fe 2 O 3 , Fe 3 O 4 , BiVO 4 , Bi 2 WO 4 , TiO 2 , SrTiO 3 , ZnO, CuO, Cu 2 O, NiO, SnO 2 , CoO, In 2 O 3 , WO 3 , MgO, CaO, La 2 O 3 , Nd 2 O 3 , Y 2 O 3 , CeO 2 , PbO, ZrO 2 , Co 3 O 4 , and Al 2 O 3It can include at least one selected from the group consisting of.

[0018] In one embodiment, the volume ratio of the liquid metal to the solid particles may be from 99:1 to 70:30.

[0019] In one embodiment, the stretchable polymer is polydimethylsiloxane (PDMS), styrene-ethylene / butylene-styrene triblock copolymer (SEBS), styrene-ethylene / butylene-styrene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride (PP-g-MA), polyethylene-graft-acrylic acid (PE-g-AA), poly-propylene-graft-acrylic acid (It can contain at least one selected from the group consisting of maleic anhydride grafted polypropylene (PP-g-AA), polyurethane (PU), polyethylene terephthalate (PET), polyethylene sulfone (PES), polymethacrylate (PMA), polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide (PI), polypropylene (PP), ethylene vinyl acetate (EVA), amorphous polyethylene terephthalate (APET), polypropylene terephthalate (PPT), polyethylene terephthalate glycol (PETG), polycyclohexylene dimethylene terephthalate (PCTG), modified triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), dicyclopentadiene polymer (DCPD), cyclopentadiene polymer (CPD), polyarylate (PAR), polyetherimide (PEI), silicone resin, fluororesin, and modified epoxy resin.;

[0020] The method for manufacturing a stretchable anisotropic conductive film according to another embodiment of the present invention includes a step of patterning a photoresist on a substrate, a step of surface-treating the substrate on which the photoresist is patterned, a step of coating a stretchable polymer on the surface-treated substrate, a step of thermally curing the coated stretchable polymer, a step of removing the patterned photoresist, a step of removing the substrate, and a step of filling a liquid metal into the removed photoresist space.

[0021] In one embodiment, the surface treatment can be performed using O 2 plasma, a silane-based substance, or both.

[0022] In one embodiment, the silane-based substance can be carried out by at least one method selected from the group consisting of fluorodecyltrichlorosilane (FDTS), methacryloxypropyltrimethoxysilane (MPTMS), undecenyltrichlorosilane (UTS), vinyl-trichlorosilane (VTS), decyltrichlorosilane (DTS), octadecyltrichlorosilane (OTS), dimethyldichlorosilane (DDMS), dodecenyltrichlorosilane (DDTS), fluoro-tetrahydrooctyltrimethylchlorosilane (FOTS), perfluorooctyldimethylchlorosilane, and silanes, chlorosilanes, fluorosilanes, methoxysilanes, alkylsilanes, and aminosilanes including aminopropylmethoxysilane (APTMS).

[0023] In one embodiment, after the step of filling the removed photoresist space with liquid metal, the step of adding solid particles to the liquid metal can further be included.

[0024] The stretchable electronic device according to another embodiment of the present invention includes a stretchable anisotropic conductive film according to one embodiment of the present invention or a stretchable anisotropic conductive film manufactured by a method for manufacturing a stretchable anisotropic conductive film according to another embodiment of the present invention.

[0025] In one embodiment, the stretchable electronic device can include at least one selected from the group consisting of a flexible display, a stretchable display, a semiconductor test socket, a sensor, and an electronic skin.

Advantages of the Invention

[0026] The stretchable anisotropic conductive film according to one embodiment of the present invention can be deformed in form by including a stretchable and conductive liquid metal in a liquid state at room temperature, and can have a high anisotropic conductivity at the metal level (>10 6 S / m).

[0027] The manufacturing method of the stretchable anisotropic conductive film according to an embodiment of the present invention has simplicity, uniformity, large-area production, and economic efficiency through a liquid metal printing process.

[0028] The stretchable electronic device according to an embodiment of the present invention includes the stretchable anisotropic conductive film according to an embodiment of the present invention, and thus can be applied to various flexible electronic devices or wearable displays.

Brief Description of the Drawings

[0029]

Figure 1a

Figure 1b

Figure 2a

Figure 2b

Figure 3a

Figure 3b

Figure 3c

Figure 3d

Figure 3e

Figure 3f

Figure 3g

Figure 4

[0030] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, various changes may be made to the embodiments, and the scope of the patent application is not limited or restricted by such embodiments. It should be understood that all changes, equivalents, or alternatives to the embodiments are included in the scope of the rights.

[0031] The terms used in the embodiments are merely used for the purpose of explanation and are not to be construed as having an intention to limit. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "including" or "having" indicate the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0032] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the technical field to which this embodiment belongs. Commonly used predefined terms should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted as having an ideal or overly formal meaning unless clearly defined herein.

[0033] In addition, when describing with reference to the accompanying drawings, regardless of the reference numerals in the drawings, the same components shall be given the same reference numerals, and duplicate descriptions thereof shall be omitted. In the description of the embodiments, if the specific description of the related known art is determined to obscure the gist of the embodiments unnecessarily, the detailed description thereof shall be omitted.

[0034] Also, when describing the components of the embodiments, terms such as first, second, A, B, (a), (b), etc. can be used. These terms are for distinguishing the components from other components, and the essence, order, or sequence of the components are not limited by these terms.

[0035] Components including functions common to the components included in any of the embodiments shall be described using the same names in other embodiments. Unless otherwise stated, the descriptions given in any of the embodiments shall also be applicable to other embodiments, and specific descriptions within the overlapping range shall be omitted.

[0036] Hereinafter, embodiments and drawings will be specifically referred to for the stretchable anisotropic conductive film, its manufacturing method, and the stretchable electronic device including the same according to the present invention. However, the present invention is not limited to such embodiments and drawings.

[0037] The stretchable anisotropic conductive film according to an embodiment of the present invention includes a patterned stretchable polymer; and a liquid metal filled in the patterned portion of the stretchable polymer.

[0038] The stretchable anisotropic conductive film according to an embodiment of the present invention can be deformed in shape by including a stretchable and conductive liquid metal that is in a liquid state at room temperature, and has an anisotropic conductivity as high as the metal level (>10 6 S / m). Therefore, it is applicable to various flexible electronic devices or wearable displays.

[0039] FIG. 1a is a schematic diagram of a stretchable anisotropic conductive film according to an embodiment of the present invention.

[0040] Referring to FIG. 1a, a stretchable anisotropic conductive film 100 according to an embodiment of the present invention includes a patterned stretchable polymer 110 and a liquid metal 120.

[0041] The material of the stretchable polymer 110 is not particularly limited as long as it can stably support the liquid metal 120, and for example, it is made of a material having flexibility, stretchability, foldable and / or rollable characteristics.

[0042] The pattern width of the stretchable polymer 110 can vary.

[0043] The stretchable polymer 110 is patterned into a predetermined shape, or in the form of through holes punched or perforated with pressure or a laser.

[0044] In one embodiment, the liquid metal 120 can maintain a liquid state at room temperature and can have a predetermined shape due to the surface tension and interfacial tension between the liquid metal 120 and the stretchable polymer 110.

[0045] In one embodiment, the anisotropic conductive film 100 can be made anisotropic by the liquid metal 120, that is, it can be energized vertically.

[0046] In one embodiment, the liquid metal may include at least one selected from the group consisting of gallium (Ga), indium (In), tin (Sn), mercury (Hg), lead (Pb), bismuth (Bi), cadmium (Cd), eutectic gallium-indium alloy (EGaIn), gallium-indium-tin eutectic alloy (Galinstan), gallium-indium (Ga / In), gallium / lead (Ga / Pb), gallium / cadmium (Ga / Cd), gallium / zinc (Ga / Zn), gallium / tin (Ga / Sn), gallium / bismuth (Ga / Bi), gallium / thallium (Ga / Tl), tin / silver (Sn / Ag), tin / gold (Sn / Au), tin / copper (Sn / Cu), tin / nickel (Sn / Ni), lead / antimony (Pb / Sb), lead / gold (Pb / Au), and lead / cadmium (Pb / Cd).

[0047] Preferably, the liquid metal may include gallium (Ga).

[0048] In one embodiment, the liquid metal 120 may be 10 wt% - 80 wt%; 10 wt% - 50 wt%; 10 wt% - 30 wt%; 10 wt% - 20 wt%; 30 wt% - 80 wt%; 30 wt% - 50 wt%; or 50 wt% - 80 wt% of the stretchable anisotropic conductive film 100.

[0049] When the liquid metal is less than 10 wt% of the stretchable anisotropic conductive film, it is difficult to impart sufficient vertical conductivity, and when it exceeds 80 wt%, there is a problem that the stretchable polymer cannot perfectly surround the liquid metal.

[0050] In one embodiment, the liquid metal may further include solid particles dispersed therein.

[0051] FIG. 1b is a schematic diagram of a stretchable anisotropic conductive film according to another embodiment of the present invention.

[0052] Referring to FIG. 1b, a stretchable anisotropic conductive film according to an embodiment of the present invention includes a patterned stretchable polymer 110, a liquid metal 120, and solid particles 130.

[0053] The solid particles 130 can be dispersed on the surface of the liquid metal or dispersed throughout the liquid metal.

[0054] The solid particles 130 at least partially cover the side surface of the liquid metal. Thereby, after the stretchable anisotropic conductive film 100 adheres to other places, the flow of the liquid metal 120 can be prevented during desorption.

[0055] In one embodiment, the solid particles 130 may further include at least one selected from the group consisting of metal particles, metal oxide particles, and semiconductor oxide particles.

[0056] In one embodiment, the metal particles may include at least one selected from the group consisting of copper (Cu), gold (Au), platinum (Pt), silver (Ag), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), chromium (Cr), tungsten (W), molybdenum (Mo), and titanium (Ti).

[0057] In one embodiment, the solid particles may include a core-shell structure. The core-shell structure may be a core-shell structure composed of metal-metal, or may also be a core-shell structure in the form of a common conductive ball [a polymer metal (several layers may be used) with a metal thin film deposited on the surface of PS particles].

[0058] In one embodiment, the metal oxide particles or semiconductor oxide particles are SiO 2 , Fe 2 O 3 , Fe 3 O 4 , BiVO 4 , Bi 2 WO 4 , TiO 2 , SrTiO 3, ZnO, CuO, Cu 2 O, NiO, SnO 2 , CoO, In 2 O 3 , WO 3 , MgO, CaO, La 2 O 3 , Nd 2 O 3 , Y 2 O 3 , CeO 2 , PbO, ZrO 2 , Co 3 O 4 and Al 2 O 3 It may contain at least one selected from the group consisting of.

[0059] The semiconductor oxide particles can change rheology while not reacting with the liquid metal, which is different from the metal particles, and exhibit characteristics different from those of the metal particles.

[0060] When the solid particles are mixed with the liquid metal at a specific ratio, it can show a behavior of changing into a paste state.

[0061] In one embodiment, the volume ratio of the liquid metal: the solid particles may be 99:1 to 70:30; 99:1 to 80:30; 99:1 to 90:30; 90:1 to 70:30; 90:1 to 80:30; 90:1 to 90:30; 80:1 to 70:30; 80:1 to 80:30; or, 70:1 to 70:30.

[0062] When the ratio of the liquid metal: the solid particles is less than 70:30, a problem of leakage of the liquid metal occurs due to external stress, and when the ratio of the liquid metal: the solid particles exceeds 99:1, processing becomes difficult and a hardening (rigidity, solidification) problem occurs.

[0063] The average diameter of the solid particles may be 50 nm to 5 μm; 50 nm to 3 μm; 50 nm to 1 μm; 10 nm to 5 μm; 10 nm to 3 μm; 10 nm to 1 μm; 50 nm to 5 μm; 50 nm to 3 μm; 50 nm to 1 μm; 100 nm to 5 μm; 100 nm to 3 μm; 100 nm to 1 μm; 500 nm to 5 μm; 500 nm to 3 μm; 500 nm to 1 μm; 1 μm to 5 μm; 1 μm to 3 μm; or 3 μm to 5 μm.

[0064] When the average diameter of the solid particles is less than 50 nm, problems in the production of fine particles occur, and when it exceeds 5 μm, limitations occur in the size of the pattern and the thickness of the film.

[0065] Preferably, the average particle size of the solid particles may be 50 nm to 3 μm.

[0066] In one embodiment, the stretchable polymer is polydimethylsiloxane (PDMS), styrene-ethylene / butylene-styrene triblock copolymer (SEBS), styrene-ethylene / butylene-styrene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride (PP-g-MA), polyethylene-graft-acrylic acid (PE-g-AA), poly-propylene-graft-acrylic acid (It contains at least one selected from the group consisting of polypropylene grafted with acrylic acid (PP-g-AA), polyurethane (PU), polyethylene terephthalate (PET), polyethylene sulfone (PES), polymethacrylate (PMA), polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide (PI), polypropylene (PP), ethylene vinyl acetate (EVA), amorphous polyethylene terephthalate (APET), polypropylene terephthalate (PPT), polyethylene terephthalate glycol (PETG), polycyclohexylene dimethylene terephthalate (PCTG), modified triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), dicyclopentadiene polymer (DCPD), cyclopentadiene polymer (CPD), polyarylate (PAR), polyetherimide (PEI), silicone resin, fluororesin, and modified epoxy resin.;

[0067] Preferably, the stretchable polymer may be PDMS.

[0068] Figures 1a and 1b show only the stretchable polymer 110 and the liquid metal 120, but may further include a layer serving as a support base, such as an Si substrate or a glass substrate, below the stretchable polymer 110.

[0069] Figure 2a is a diagram for explaining the deformation of an anisotropic conductive film using a conventional hard conductive ball, and Figure 2b is a diagram for explaining the deformation of a stretchable anisotropic conductive film using the liquid metal of the present invention.

[0070] As shown in Figure 2a, it can be seen that the conventional anisotropic conductive film has limitations in deformation through thermocompression bonding because it uses a hard conductive ball, and it is difficult to conduct electricity with a concave lower electrode that is not a protruding lower electrode.

[0071] As shown in Fig. 2b, the stretchable anisotropic conductive film of the present invention can be deformed in accordance with the concave lower electrode form by using a stretchable and conductive liquid metal that is in a liquid state at room temperature instead of a hard conductive ball, and it can be seen that anisotropic conductivity with a high metal level (>10 6 S / m) can be imparted.

[0072] The method for manufacturing a stretchable anisotropic conductive film according to another embodiment of the present invention includes the steps of: patterning a photoresist on a substrate; surface-treating the substrate on which the photoresist is patterned; coating a stretchable polymer on the surface-treated substrate; thermally curing the coated stretchable polymer; removing the patterned photoresist; removing the substrate; and filling the liquid metal into the removed photoresist space.

[0073] Figs. 3a to 3g are schematic diagrams for explaining the method for manufacturing a stretchable anisotropic conductive film according to an embodiment of the present invention.

[0074] Referring to Fig. 3a, first, a substrate 210 is prepared, and a photoresist 220 is patterned on the substrate.

[0075] The substrate 210 is not limited by the substance and type.

[0076] In one embodiment, the substrate may include at least one selected from the group consisting of a flexible substrate, a semiconductor substrate, an insulating substrate, and a stretchable substrate.

[0077] The substrate 210 may include, for example, at least one selected from the group consisting of a silicon substrate, a P-doped silicon (P+doped-Si) substrate, a polyimide substrate, a PDMS (polydimethylsiloxane) substrate, a PET (polyethylene terephthalate) substrate, a glass substrate, and a paper substrate.

[0078] Preferably, the substrate 210 may be a silicon substrate.

[0079] The patterned photoresist 220 is formed by a stamping process based on a photolithography process using a photoresist.

[0080] The photoresist may include at least one selected from the group consisting of SU-8 50, SU-8 2, AZ nLOF2070, and AZ5214.

[0081] Through a stamping process based on a photolithography process, a polymer film having a regular array of uniform size, spacing, and high resolution can be patterned.

[0082] In the case of the conventionally reported ACF, although a complicated process is required several times, the mold can be reused through the stamping process, ensuring the simplicity and mass productivity of the process. Moreover, it has the advantage of being applicable to various types of polymers and can be extended to S-ACFs with various physical properties according to the situation.

[0083] In one embodiment, the surface treatment is O 2 The surface can be treated using plasma, a silane-based substance 230, or both.

[0084] As shown in FIG. 3b, the silane-based substance 230 is surface-treated on the substrate 210 on which the photoresist 220 is patterned.

[0085] The surface treatment is for easily peeling off the stretchable polymer later.

[0086] In one embodiment, the silane-based substance can be carried out by at least one method selected from the group consisting of fluorodecyltrichlorosilane (FDTS), methacryloxypropyltrimethoxysilane (MPTMS), undecenyltrichlorosilane (UTS), vinyl-trichlorosilane (VTS), decyltrichlorosilane (DTS), octadecyltrichlorosilane (OTS), dimethyldichlorosilane (DDMS), dodecenyltrichlorosilane (DDTS), fluoro-tetrahydrooctyltrimethylchlorosilane (FOTS), perfluorooctyldimethylchlorosilane, and silanes, chlorosilanes, fluorosilanes, methoxysilanes, alkylsilanes, and aminosilanes containing aminopropylmethoxysilane (APTMS).

[0087] Preferably, the silane-based substance may use octadecyltrichlorosilane (OTS).

[0088] For example, after performing plasma treatment on the substrate, a solution in which 2 wt% of n-octadecyltrichlorosilane (OTS) is dissolved in toluene can be spin-coated at 3,000 rpm, and toluene can be dried at a high temperature of 120 °C. 2 As shown in FIG. 3c, a stretchable polymer 240 is coated on the substrate 210 surface-treated with the silane-based substance 230.

[0089]

[0090] ​In one embodiment, the step of coating the stretchable polymer on the surface-treated substrate may be performed by at least one method selected from the group consisting of blade printing, screen printing, brush painting, spin coating, dip coating, bar coating, dropping, spray coating, inkjet printing, and spotting.

[0091] Preferably, the coating may be based on the spin coating method.

[0092] In one embodiment, the stretchable polymer is polydimethylsiloxane (PDMS), styrene-ethylene / butylene-styrene triblock copolymer (SEBS), styrene-ethylene / butylene-styrene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride (PP-g-MA), polyethylene-graft-acrylic acid (PE-g-AA), poly-propylene-graft-acrylic acid (It may contain at least one selected from the group consisting of polypropylene grafted with acrylic acid (PP-g-AA), polyurethane (PU), polyethylene terephthalate (PET), polyethylene sulfone (PES), polymethacrylate (PMA), polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide (PI), polypropylene (PP), ethylene vinyl acetate (EVA), amorphous polyethylene terephthalate (APET), polypropylene terephthalate (PPT), polyethylene terephthalate glycol (PETG), polycyclohexylene dimethylene terephthalate (PCTG), modified triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), dicyclopentadiene polymer (DCPD), cyclopentadiene polymer (CPD), polyarylate (PAR), polyetherimide (PEI), silicone resin, fluororesin, and modified epoxy resin.;

[0093] Preferably, the stretchable polymer may be PDMS.

[0094] The stretchable polymer may be coated with a thickness lower than that of the photoresist pattern.

[0095] Next, the coated stretchable polymer is thermally cured.

[0096] In one embodiment, the step of thermally curing the coated stretchable polymer may be performed in a temperature range of 50°C to 100°C; 50°C to 80°C; 50°C to 60°C; 70°C to 100°C; 70°C to 80°C; or 80°C to 100°C for 5 minutes to 60 minutes; 5 minutes to 60 minutes.

[0097] As shown in FIG. 3d, the photoresist is removed.

[0098] Therefore, a patterned polymer film with holes having a shape opposite to that of the photoresist pattern can be obtained.

[0099] By adjusting the size and depth of the pattern, anisotropic conductive films in various forms can be manufactured quickly and easily.

[0100] As shown in FIG. 3e, remove the substrate.

[0101] O on the substrate 2 Due to plasma treatment and surface treatment with a silane-based substance on the substrate, the separation between the substrate and the polymer is easy.

[0102] As shown in FIG. 3f, fill the removed photoresist space with liquid metal 250.

[0103] In one embodiment, the liquid metal 250 can maintain a liquid state at room temperature and its shape is deformed accordingly. It can have a predetermined shape due to the surface tension and interfacial tension between the liquid metal 250 and the stretchable polymer 240.

[0104] In one embodiment, the anisotropic conductive film can be anisotropic, i.e., conduct electricity vertically, by the liquid metal 250.

[0105] In one embodiment, the liquid metal may include at least one selected from the group consisting of gallium (Ga), indium (In), tin (Sn), mercury (Hg), lead (Pb), bismuth (Bi), cadmium (Cd), gallium-indium eutectic alloy (eutectic gallium-indium alloy, EGaIn), gallium-indium-tin eutectic alloy (galinstan, Galinstan), gallium-indium (Ga / In), gallium / lead (Ga / Pb), gallium / cadmium (Ga / Cd), gallium / zinc (Ga / Zn), gallium / tin (Ga / Sn), gallium / bismuth (Ga / Bi), gallium / thallium (Ga / Tl), tin / silver (Sn / Ag), tin / gold (Sn / Au), tin / copper (Sn / Cu), tin / nickel (Sn / Ni), lead / antimony (Pb / Sb), lead / gold (Pb / Au), and lead / cadmium (Pb / Cd).

[0106] Preferably, the liquid metal may contain gallium (Ga).

[0107] In one embodiment, the step of filling the removed photoresist space with liquid metal may be performed by at least one method selected from the group consisting of blade printing, screen printing, brush painting, spin coating, dip coating, bar coating, dropping, spray coating, inkjet printing, and spotting.

[0108] Preferably, the coating may be based on blade printing. Blade printing is different from screen printing in that a double blade containing liquid metal is separated from the substrate by a height of several tens to several hundreds of micrometers. Different from inkjet printing that applies pressure, no pressure is applied.

[0109] To explain the printing method of liquid metal, after contacting the liquid metal contained in the blade of the printer with a polymer film having holes pre-patterned thereon, it is moved at a constant speed. The liquid metal wets into the hole part, fills the hole and conducts electricity in the vertical direction. On the polymer film part without holes, the liquid metal is non-wetting and no liquid metal remains, and the conductivity in the horizontal direction is lost.

[0110] Through the blade printing process, liquid metal can be printed on a patterned polymer in a simple manner to induce non-wettability, and the liquid metal can be selectively printed only on the patterned portions. The liquid metal can be patterned to have anisotropic conductivity that imparts conductivity only in the vertical direction. This overcomes the limitations of liquid metal that are difficult to pattern due to high surface tension through surface oxide film and hydrodynamic analysis.

[0111] In the case of ACF using the conventional rubbing process, not only is the process complex, but it was difficult to uniformly embed conductive particles in all patterns. However, through the printing process of filling only the liquid metal in specific portions using the wettability of the liquid metal, the simplicity and uniformity of the process can be ensured.

[0112] Also, conventionally, many elements were required for large-area applications, but large-area applications can be easily achieved by a simple method of adjusting the size of the print head.

[0113] It is also easy to ensure economy in the simple printing process at room temperature compared to the conventional methods that require many high-temperature processes.

[0114] Therefore, the liquid metal printing process is a process that simplifies the process, improves uniformity, enables large-area applications, and is economical.

[0115] When the liquid metal is in a particulate state, an oxide film is formed on the particle surface. When various particles are in contact, an insulating state occurs, and an additional process such as microwave irradiation is required to impart conductivity between the particles. However, the corresponding printing method does not require such a process because it imparts vertical conductivity with liquid metal in a bulk form that is not liquid metal particles.

[0116] The region with holes is filled with liquid metal, which plays a role in imparting conductivity in the vertical direction. In the polymer region without holes, for example, a non-conductive oxide film with a thickness of 3 nm is formed, so that the problem of crosstalk of conducting electricity horizontally does not occur.

[0117] In one embodiment, after the step of filling the removed photoresist space with liquid metal, the method further includes the step of adding solid particles to the liquid metal.

[0118] As shown in FIG. 3g, solid particles 260 are added to the liquid metal 250.

[0119] The solid particles 260 can be dispersed on the surface of the liquid metal 250 or dispersed in the entire liquid metal 250 to form an alloy. After forming the alloy, the residue of the solid particles is removed.

[0120] The solid particles 260 can at least partially cover the side surface of the liquid metal 250. Therefore, when the stretchable anisotropic conductive film adheres to other places and then desorbs, it can prevent the flow of the liquid metal 250 in a liquid state.

[0121] In one embodiment, the solid particles 260 may further include at least one selected from the group consisting of metal particles, metal oxide particles, and semiconductor oxide particles.

[0122] In one embodiment, the solid particles may include a core-shell structure. In addition to the core-shell composed of metal-metal, the core-shell structure may also be in the form of a conventional conductive ball [a polymer metal (several layers may be acceptable) with a metal thin film deposited on the surface of PS particles].

[0123] In one embodiment, the metal particles may include at least one selected from the group consisting of copper (Cu), gold (Au), platinum (Pt), silver (Ag), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), chromium (Cr), tungsten (W), molybdenum (Mo), and titanium (Ti).

[0124] Preferably, the metal particles may be iron (Fe) or nickel (Ni).

[0125] In one embodiment, the metal oxide particles or semiconductor oxide particles are Fe 2 O 3 、Fe 3 O 4 、BiVO 4 、Bi 2 WO 4 、TiO 2 、SrTiO 3 、ZnO, CuO, Cu 2 O 2 、NiO, SnO 2 O 3 、WO 3 、MgO, CaO, La 2 O 3 、Nd 2 O 3 、Y 2 O 3 、CeO 2 、PbO, ZrO 2 、Co 3 O 4 、and Al 2 O 3 and may include at least one selected from the group consisting of.

[0126] Preferably, the metal oxide particles or semiconductor oxide particles may be Fe 2 O 3 It may be.

[0127] When solid particles are mixed with the liquid metal at a specific ratio, it exhibits a behavior of changing into a paste state. By forming an alloy with a compositional ratio having paste physical properties, stability and high conductivity can be maintained during stretching of the stretchable anisotropic conductive film.

[0128] The stretchable electronic element according to a further embodiment of the present invention includes a stretchable anisotropic conductive film manufactured by the stretchable anisotropic conductive film according to an embodiment of the present invention or a manufacturing method of a stretchable anisotropic conductive film according to another embodiment of the present invention.

[0129] In one embodiment, the stretchable electronic element may include at least one selected from the group consisting of a flexible display, a stretchable display, a semiconductor test socket, a sensor, and an electronic skin.

[0130] Since the laminated structures of the flexible display and the stretchable display form a vertical junction through the stretchable anisotropic conductive film, each display can include an average of 5-6 layers of stretchable anisotropic conductive film.

[0131] Due to the development of materials and process technologies, the size of electronic elements, circuits, and wirings have been miniaturized, mechanical flexibility and deformability are required, and for the electrical connection between the miniaturized electronic elements and circuits, the highly regular array of the stretchable anisotropic conductive film in the present invention is essential.

[0132] Similar to the stretchable anisotropic conductive film, the semiconductor test socket requires anisotropic conductivity. Recently, the application range of silicon rubber sockets has been expanded to the high-value-added system semiconductor market such as central processing units (CPUs) and graphics processing units (GPUs). Along with this, technologies for fine pitches with fine, various sizes and shapes, and high ductility and low-pressure contact of large areas are required. Conventional pogo pin and silicon robosoft socket methods are difficult to simultaneously ensure high flexibility / uniform contact / high conductivity, and in order to solve this problem, a test socket for large area / high flexibility / high conductivity / high density is required, and the stretchable anisotropic conductive film according to an embodiment of the present invention can be used.

[0133] The present invention will be described in detail below with reference to the following embodiments and comparative examples. However, the technical idea of the present invention is not limited or restricted thereby.

[0134] [Embodiment]

[0135] After spin-coating SU-8 50 photoresist on a silicon substrate at a height of 40 μm (3,000 rpm, 30 seconds), soft baking was continuously performed on a hot plate at 65°C for 5 minutes and then at 95°C for 15 minutes.

[0136] Next, in order to open the space for forming the polymer, the SU-8 50 photoresist was exposed using a UV lamp and a photomask at 250 J / cm 2 Then, the substrate on which the photoresist was patterned was continuously baked on a hot plate at 65°C for 1 minute and then at 95°C for 4 minutes, followed by post-exposure bake (PEB).

[0137] Next, it was developed with SU-8 developer for 6 minutes, rinsed with isopropyl alcohol (IPA), and then dried with N 2 gas. Next, the photolithography process was finished with a curing step of performing hard baking on a hot plate at 150°C for 30 minutes.

[0138] The photoresist on the substrate was patterned into square columns with horizontal, vertical, and height dimensions of 20 μm, 20 μm, and 40 μm, respectively.

[0139] Next, after O 2 plasma treatment on the silicon substrate on which the square columns of the photoresist were patterned, a solution in which 2 wt% of n-octadecyltrichlorosilane was dissolved in toluene was spin-coated at 3,000 rpm, and toluene was removed at a high temperature of 120°C.

[0140] The polymer was spin-coated at a thickness of 1 μm to 10 μm, which is lower than the pillars of the photoresist, and thermally cured to obtain a patterned polymer film having holes with a shape opposite to that of the photoresist pattern.

[0141] The polymer film was peeled off from the substrate to obtain a patterned polymer film.

[0142] Figure 4 is an image of the patterned surface of the polymer film through the stamping process based on the photolithography process according to the embodiment of the present invention.

[0143] Referring to Figure 4, the left side is an image of the patterned surface of the polymer film, and the right side is an image of the surface in a state where the liquid metal is filled after liquid metal printing. It can be seen that a polymer film having a regular arrangement of uniform size, interval, and high resolution at a resolution of 10 μm and a resolution of 20 μm is patterned.

[0144] The patterned polymer film was placed on a printing substrate, and liquid metal was printed in a square shape with a side length of 20 μm to produce a stretchable anisotropic conductive film.

[0145] Although the embodiments have been described as above, those having ordinary knowledge in the art can apply various technical modifications and deformations based on the above. For example, the described technology may be executed in an order different from the described method, and / or the components of the described system, structure, device, circuit, etc. may be combined or assembled in a form different from the described method, or may be replaced or substituted by other components or equivalents, and appropriate results can still be achieved.

[0146] Therefore, other realizations, other embodiments, and equivalents to the claims, etc. also fall within the scope of the claims described later.

Claims

1. A patterned stretchable polymer, Liquid metal filled in the patterned portion of the stretchable polymer, A stretchable anisotropic conductive film comprising:

2. The stretchable anisotropic conductive film according to claim 1, wherein both sides of the anisotropic conductive film are energized by the liquid metal.

3. The liquid metal is selected from the group consisting of gallium (Ga), indium (In), tin (Sn), mercury (Hg), lead (Pb), bismuth (Bi), cadmium (Cd), gallium-indium eutectic alloy (eutectic gallium-indium alloy, EGaIn), gallium-indium-tin eutectic alloy (galinstan, Galinstan), gallium-indium (Ga / In), gallium / lead (Ga / Pb), gallium / cadmium (Ga / Cd), gallium / zinc (Ga / Zn), gallium / tin (Ga / Sn), gallium / bismuth (Ga / Bi), gallium / thallium (Ga / Tl), tin / silver (Sn / Ag), tin / gold (Sn / Au), tin / copper (Sn / Cu), tin / nickel (Sn / Ni), lead / antimony (Pb / Sb), lead / gold (Pb / Au), and lead / cadmium (Pb / Cd). The stretchable anisotropic conductive film according to claim 1, comprising at least one selected from the group consisting of:

4. The liquid metal is 10% to 80% by weight of the stretchable anisotropic conductive film according to claim 1.

5. Further comprising solid particles dispersed in the liquid metal, The solid particles further comprise at least one selected from the group consisting of metal particles, metal oxide particles, and semiconductor oxide particles, The solid particles have a core-shell structure, The metal particles include at least one selected from the group consisting of copper (Cu), gold (Au), platinum (Pt), silver (Ag), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), chromium (Cr), tungsten (W), molybdenum (Mo), and titanium (Ti). The metal oxide particles or semiconductor oxide particles are SiO ２ , Fe ２ O ３ , Fe ３ O ４ , BiVO ４ , Bi ２ WO ４ , TiO ２ , SrTiO ３ , ZnO, CuO, Cu ２ O, NiO, SnO ２ , CoO, In ２ O ３ , WO ３ , MgO, CaO, La ２ O ３ , Nd ２ O ３ , Y ２ O ３ , CeO ２ , PbO, ZrO ２ , Co ３ O ４ , and at least one selected from the group consisting of Al ２ O ３ , the stretchable anisotropic conductive film according to claim 1.

6. The stretchable anisotropic conductive film according to claim 5, wherein the volume ratio of the liquid metal to the solid particles is 99:1 to 70:

30.

7. The stretchable polymer is Polydimethylsiloxane (PDMS), styrene-ethylene / butylene-styrene triblock copolymer (styrene-ethylene / butylene-styrene triblock copolymer; SEBS), styrene-ethylene / butylene-styrene-graft-maleic anhydride copolymer (styrene-ethylene / butylene-styrene-graft-maleic anhydride copolymer; SEBS-g-MA), polyethylene-graft-maleic anhydride (polyethylene-graft-maleic anhydride; PE-g-MA), polypropylene-graft-maleic anhydride copolymer (polypropylene-graft-maleic anhydride copolymer; SEBS-g-MA), polyethylene-graft-maleic anhydride (polyethylene-graft-maleic anhydride; PE-g-MA), polypropylene-graft-maleic anhydride (polypropylene-graft-maleic anhydride; PP-g-MA), polyethylene-graft-acrylic acid (polyethylene-graft-acrylic acid; PE-g-AA), poly-propylene-graft-acrylic acid (poly-propylene-graft-acrylic acid;The stretchable anisotropic conductive film according to claim 1, comprising at least one selected from the group consisting of polypropylene-grafted acrylic acid (PP-g-AA), polyurethane (PU), polyethylene terephthalate (PET), polyethylene sulfone (PES), polymethacrylate (PMA), polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide (PI), polypropylene (PP), ethylene vinyl acetate (EVA), amorphous polyethylene terephthalate (APET), polypropylene terephthalate (PPT), polyethylene terephthalate glycol (PETG), polycyclohexylene dimethylene terephthalate (PCTG), modified triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), dicyclopentadiene polymer (DCPD), cyclopentadiene polymer (CPD), polyarylate (PAR), polyetherimide (PEI), silicone resin, fluororesin, and modified epoxy resin.;

8. A step of patterning a photoresist on a substrate, A step of surface-treating the substrate on which the photoresist is patterned, Coating a stretchable polymer on the surface-treated substrate; Thermally curing the coated stretchable polymer; Removing the patterned photoresist; Removing the substrate; Filling the removed photoresist space with liquid metal; A method for manufacturing a stretchable anisotropic conductive film, comprising the above steps.

9. The surface treatment is O ２ performed using plasma, a silane-based substance, or both The silane-based substance is at least one selected from the group consisting of fluorodecyltrichlorosilane (FDTS), methacryloxypropyltrimethoxysilane (MPTMS), undecenyltrichlorosilane (UTS), vinyl-trichlorosilane (VTS), decyltrichlorosilane (DTS), octadecyltrichlorosilane (OTS), dimethyldichlorosilane (DDMS), dodecenyltrichlorosilane (DDTS), fluoro-tetrahydrooctyltrimethylchlorosilane (FOTS), perfluorooctyldimethylchlorosilane, and silanes, chlorosilanes, fluorosilanes, methoxysilanes, alkylsilanes, and aminosilanes including aminopropylmethoxysilane (APTMSS), and is executed by at least one method selected from the group. The method for manufacturing a stretchable anisotropic conductive film according to Claim 8.

10. The method for manufacturing a stretchable anisotropic conductive film according to Claim 8, further comprising adding solid particles to the liquid metal after the step of filling the removed photoresist space with liquid metal.

11. A stretchable electronic device comprising the stretchable anisotropic conductive film according to Claim 1 or the stretchable anisotropic conductive film manufactured by the method for manufacturing a stretchable anisotropic conductive film according to Claim 8.

12. The stretchable electronic device according to Claim 11, wherein the stretchable electronic device includes at least one selected from the group consisting of a flexible display, a stretchable display, a semiconductor test socket, a sensor, and an electronic skin.

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