Stretchable ACF, its manufacturing method, and interface bonding member and element containing the same

Abstract

The present invention provides an expandable ACF, a method for producing the same, and an interface bonding member and device containing the same.

Description

Detailed Description of the Invention

[0001] [Technical Field] The present invention relates to an expandable ACF, a method for producing the same, and an interface bonding member and element containing the same.

[0002] [Background technology] Soft electronics have attracted great interest in a wide range of applications, including stretchable displays, implantable medical devices, and electronic wearables. As research has progressed, researchers have fabricated more complex and multi-layered devices. However, there are still challenges that must be overcome in complex soft devices to move closer to commercialization.

[0003] One of them is the physical and electrical interface between the device and layers: the mismatch in elastic moduli between hard-soft-soft and hard-soft layers can induce delamination and cracking during repeated deformation, resulting in degradation of device performance.

[0004] To solve these problems, anisotropic conductive film (ACF), one of the electrical interconnection methods for rigid electronic devices, has a simple manufacturing process and ensures both mechanical and electrical connections, making it suitable for soft electronic applications. It is known as a composite of polymer and metal particles.

[0005] Previous research into anisotropic conductive films has reported imidazole epoxy resin-based ACFs with randomly distributed solder balls (J. Park, JC Park, S. Lee, and K. Paik, "Piezoelectric Ceramics and Flexible Printed Circuits' Interconnection Using Sn58Bi Solder Anisotropic Conductive Films for Flexible Ultrasound Transducer Assembly," in IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 9, no. 9, pp. 1897-1903, Sept. 2019, doi: 10.1109 / TCPMT.2019.2907927.). However, the randomly aggregated conductive fillers had the problem of a high probability of short circuits and inefficient resolution.

[0006] Therefore, it was necessary to develop an ACF that could solve these problems and have excellent elasticity and conductivity.

[0007] Summary of the Invention [Problem to be solved by the invention] The technical problem to be achieved by the present invention is to provide an expandable ACF having excellent stretchability, a method for producing the same, and an interface bonding member and element containing the same.

[0008] However, the problems to be solved by the present invention are not limited to those mentioned above, and further problems not mentioned will be clearly understood by those skilled in the art from the following description.

[0009] [Means for solving the problem] According to one aspect of the present invention, there is provided an expandable ACF comprising a polymer film and conductive particles inserted and aligned in the polymer film, the conductive particles being exposed on the outer surfaces of the upper and lower parts of the polymer film.

[0010] According to one aspect of the present invention, there is provided a method for manufacturing an extensible ACF, the method including the steps of: manufacturing a polymer film patterned with a pattern including protrusions and recesses; disposing conductive particles in the recesses of the patterned polymer film to obtain a polymer film in which the conductive particles are aligned; and hot-compressing the polymer film in which the conductive particles are aligned.

[0011] According to one aspect of the present invention, there is provided an interface bonding member comprising an expandable ACF.

[0012] According to one aspect of the present invention, there is provided an element including at least one of an electrode and an electronic component, and the interface bonding member.

[0013] [Effects of the Invention] The extensible ACF according to one embodiment of the present invention has excellent extensibility, i.e., stretchability, and changes in response to deformation of the substrate, making it suitable for flexible electronic devices.

[0014] The stretchable ACF according to one embodiment of the present invention has excellent adhesive strength and can be applied to electronic devices to firmly bond the interfaces of different members.

[0015] The expandable ACF according to one embodiment of the present invention contains regularly arranged conductive particles and can maintain uniform and consistent conductivity.

[0016] The expandable ACF according to one embodiment of the present invention completely eliminates short circuits between adjacent wirings due to particle aggregation, and can connect high-resolution wirings.

[0017] The expandable ACF according to one embodiment of the present invention can be used in various fields because the region where the conductive particles are arranged can be freely controlled.

[0018] The stretchable ACF according to one embodiment of the present invention has excellent stretchability and stretchability, does not decrease in conductivity even when subjected to physical stimuli, and is also excellent in stability.

[0019] In the expandable ACF according to one embodiment of the present invention, conductive microparticles of the same size are inserted into the polymer film in layers, so there is no difference in height.

[0020] The method for producing an expandable ACF according to one embodiment of the present invention can provide an ACF with excellent stretchability and conductivity.

[0021] The interface bonding member according to one embodiment of the present invention can be interposed between soft and soft members or between soft and hard members to firmly bond the interface.

[0022] The interface bonding member according to an embodiment of the present invention can bond different members together even in a low-temperature process.

[0023] In the device according to one embodiment of the present invention, the physical and chemical bond between the expandable ACF and the electrode or substrate is strong, resulting in excellent interfacial bonding strength between the electrode and the substrate.

[0024] The effects of the present invention are not limited to those described above, and effects not mentioned will be clearly understood by those skilled in the art from the present specification and the accompanying drawings.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a stretchable ACF film according to one embodiment of the present invention.

[0026] FIG. 2 is a schematic diagram of a method for producing expandable ACF according to one embodiment of the present invention.

[0027] FIG. 3 is a schematic diagram showing the conductive particles of the expandable ACF according to one embodiment of the present invention functioning as a conductive path.

[0028] FIG. 4 is a schematic diagram for calculating the minimum width of connectable wiring in a form in which conductive particles of an expandable ACF according to one embodiment of the present invention are arranged.

[0029] FIG. 5 is an SEM image of a cross section of a patterned polymer film in which conductive particles are aligned according to the first embodiment.

[0030] [Figure 6] SEM image of the cross section of the expandable ACF produced in embodiment 1.

[0031] [Figure 7A] OM image of the surface of the expandable ACF produced in embodiment 1.

[0032] [Figure 7B] OM image of the surface of the expandable ACF produced in embodiment 1.

[0033] FIG. 8 shows the stress-strain curves of the stretchable ACFs of Examples 1 to 3 and the films of Reference Examples 1 and 2.

[0034] FIG. 9 is a graph showing the connection resistance and alignment retention of the ACFs produced in the first, fourth, and fifth embodiments.

[0035] [FIG. 10A] to [FIG. 10C] are surface OM images of the expandable ACFs produced in embodiments 1, 4, and 5, respectively.

[0036] [Figure 11] An OM image taken on the top surface of a laminate containing the expandable ACF produced in embodiment 1.

[0037] [Fig. 12] Results of testing the electrical performance of the laminate of Test Example 5.

[0038] FIG. 13 is a graph showing the adhesive strength as a function of distance for laminates produced in Examples 6 to 8 and Reference Examples 3 and 4.

[0039] FIG. 14 is a graph showing pressure and relative current over time applied to the laminate of Example 9.

[0040] 15 and 16 are graphs showing the stretch over time and relative current applied to laminates of embodiments 10 and 11, respectively.

[0041] [Mode for Carrying Out the Invention] In this specification, when any part "comprises" any component, it does not mean that other components are excluded, unless otherwise specified, and it means that other components may also be included.

[0042] Throughout this specification, when an element is referred to as being "on" another element, this includes not only when the element is in contact with the other element, but also when there is an additional element between the two elements.

[0043] Throughout this specification, the unit "parts by weight" refers to the weight ratio between each component.

[0044] Throughout this specification, "A and / or B" means "A and B, or A or B."

[0045] The present invention will now be described in more detail.

[0046] According to one embodiment of the present invention, there is provided an expandable ACF comprising a polymer film and conductive particles inserted and aligned in the polymer film, the conductive particles being exposed to the exterior of upper and lower surfaces of the polymer film.

[0047] According to one embodiment of the present invention, the extensible ACF has excellent extensibility, i.e., elasticity, and can change in response to deformation of a substrate, making it suitable for flexible electronic devices. It also has excellent adhesive strength, allowing it to be used in electronic devices and firmly bond the interfaces of different components. It also contains regularly arranged conductive particles, allowing it to maintain uniform and consistent conductivity. The region where the conductive particles are arranged can be freely controlled, making it suitable for use in various fields.

[0048] According to one embodiment of the present invention, the extensible ACF includes a polymer film, which has excellent elasticity and high elongation, but low conductivity, allowing the ACF to be formed so that electricity flows only at desired locations.

[0049] According to an embodiment of the present invention, the polymer film may include a heat-curable rubber grafted with maleic anhydride. The heat-curable rubber grafted with maleic anhydride has excellent flexibility and stretchability, making it suitable as a material for the polymer film.

[0050] According to one embodiment of the present invention, the heat-curable rubber is selected from styrene-ethylene-butylene-styrene (SEBS), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS), polyurethane (PU)-based rubber, and polyolefin (PO)-based rubber, and is preferably styrene-ethylene-butylene-styrene, but is not limited to the above.

[0051] According to one embodiment of the present invention, the heat-curable rubber may have a maleic anhydride content of 1 wt % or more relative to the total weight of the rubber. When the maleic anhydride content falls within this range, it has the effect of providing a sufficient number of bond formation sites relative to the adhesive area.

[0052] According to one embodiment of the present invention, the thickness of the polymer film may be 10 μm to 30 μm, but is not limited to this range.

[0053] According to one embodiment of the present invention, the expandable ACF includes conductive particles, which, in contrast to the polymer film, can provide an ACF with selective conductivity in regions with at least a surface conductive property.

[0054] According to an embodiment of the present invention, the conductive particles are inserted and aligned in the polymer film, i.e., the conductive particles may be embedded in the polymer film or may be aligned in a regular pattern.

[0055] The term "aligned" means that a plurality of conductive particles are arranged at equal intervals or at intervals having a specific regularity. That is, when any one conductive particle is inserted into the polymer film, other conductive particles may be positioned at a predetermined interval, and further conductive particles may also be positioned at a predetermined interval from the other conductive particles.

[0056] According to an embodiment of the present invention, the conductive particles may be arranged in any one of a lattice pattern, a honeycomb pattern, a line pattern, and a square pattern, but are not limited thereto, and may be arranged in various patterns as needed.

[0057] According to an embodiment of the present invention, the distance between the conductive particles may be 10 μm to 400 μm, but is not limited thereto and may be adjusted depending on the arrangement, the diameter of the conductive particles, and the application field of the expandable ACF. The distance between the conductive particles means the distance from the center of one conductive particle to the center of another conductive particle.

[0058] According to one embodiment of the present invention, for example, when the conductive particles are arranged in a lattice pattern, if the polymer film is a two-dimensional plane, and one conductive particle is the origin where the x-axis and y-axis intersect, other conductive particles may be located at positions (x, y) = (L, 0), (-L, 0), (0, L), (0, -L), (L, L), (L, -L), (-L, -L), and (-L, L), and each conductive particle may again become the origin and conductive particles may be arranged at a distance L in the same vertical direction.

[0059] That is, according to one embodiment of the present invention, the distance between the conductive particles may be L to 1.41 L. Specifically, the distance between the conductive particles at the origin and the particles perpendicular to the x-axis and y-axis is L, and the distance between the conductive particles on a plane other than the axes is √2L, or about 1.41 L.

[0060] In this case, that is, when the conductive particles are arranged in a lattice pattern, L may be 15 μm to 400 μm.

[0061] Furthermore, for example, when the conductive particles are arranged in a honeycomb pattern, if one conductive particle is the origin where the x-axis and y-axis intersect when the polymer film is a two-dimensional plane, other conductive particles are located at positions (x, y) = (L, 0), (-L, 0), (0.5L, 1.73L), (-0.5L, 1.73L), (0.5L, -1.73L), and (-0.5L, -1.73L), and each conductive particle again becomes the origin, and six conductive particles are arranged at a distance of L.

[0062] That is, according to one embodiment of the present invention, the distance between the conductive particles is L. Specifically, the conductive particle at the origin and the six closest conductive particles are all located at a distance of L.

[0063] In this case, that is, when the conductive particles are arranged in a honeycomb pattern, L may be 15 μm to 400 μm.

[0064] When the conductive particles are aligned at intervals within this range, the regular arrangement of particle diameters results in consistent performance, such as conductivity and resolution, across the entire area of ​​the expandable ACF, enabling precise design of electrode interconnections.

[0065] According to one embodiment of the present invention, the material and shape of the conductive particles are not particularly limited, but it is preferable that at least the surface is made of a metal material and be spherical. Specifically, the conductive particles may be metal particles, hollow metal particles, non-conductive materials inside, or particles with a conductive coating only on the surface. However, the conductive particles are not limited to the above, and any particles commonly used in the art may be used.

[0066] According to one embodiment of the present invention, the conductive particles may have a core-shell structure including a core containing a polymer and a shell containing a metal. When the conductive particles have a core containing a polymer and a shell containing a metal, uniformly sized conductive particles can be used in the expandable ACF, which reduces the weight of the expandable ACF and the device, thereby reducing production costs.

[0067] According to one embodiment of the present invention, the diameter of the conductive particles may be 10 μm to 200 μm. This range corresponds to the particle size range of conductive particles used in the art and allows for various technical applications. Furthermore, each individual conductive particle may have the same diameter. When conductive particles with the same diameter are used, there is no difference in height of the expandable ACF, so a separate bumper layer for anisotropic conduction is not required.

[0068] According to one embodiment of the present invention, the conductive particles may be aligned in a partial region of the polymer film. That is, when the polymer film is a two-dimensional plane, the region where the conductive particles are aligned may exist only in a part of the corresponding area. The position of the region may vary depending on the device using the expandable ACF, and the position of the region may be adjusted according to the purpose.

[0069] The number of regions may be one or more, and the number of regions may vary depending on the device in which the expandable ACF is used or the purpose of use.

[0070] 1 is a schematic diagram of an expandable ACF membrane according to one embodiment of the present invention, in which the conductive particles are aligned in a region of a polymer film.

[0071] According to one embodiment of the present invention, the conductive particles are exposed to the exterior of the upper and lower surfaces of the polymer film. When the conductive particles are exposed to the exterior of the upper and lower surfaces of the polymer film, they can function as a conductive path by allowing current flowing from a member in contact with one side of the stretchable ACF to flow to another member in contact with the other side of the stretchable ACF.

[0072] FIG. 3 is a schematic diagram of an expandable ACF according to one embodiment of the present invention, in which conductive particles function as conductive paths.

[0073] Referring to FIG. 3, it can be seen that in the stretchable ACF according to one embodiment of the present invention, current flows vertically through the exposed portions of the upper and lower surfaces of the polymer film as vertical conduction paths (blue arrows), but current cannot flow horizontally (black arrows) due to the non-conductivity of the polymer film.

[0074] According to one embodiment of the present invention, 10% to 30%, 14% to 30%, 10% to 21%, or 14% to 21% of the outer surface of the conductive particles is exposed to the outside of the polymer film. When the outer surface is exposed within this range, the step of the expandable ACF can be minimized, while the connection resistance is low and excellent conductivity can be ensured.

[0075] According to an embodiment of the present invention, the region where the conductive particles are exposed may be on the same plane as the polymer film, and the region where the conductive particles are exposed may be formed by deformation of the conductive particles during a manufacturing process of the expandable ACF.

[0076] The stretchable ACF according to one embodiment of the present invention may have a stress of 10 MPa or less, 8 MPa or less, or 5 MPa or less when stretched at a stretch rate of 100%. When the stretchable ACF has a stress within the above range when stretched at a stretch rate of 100%, the stretchable ACF has excellent stretchability and exhibits excellent conductive stability without a decrease in conductivity even when subjected to physical stimuli.

[0077] Furthermore, the stretchable ACF according to one embodiment of the present invention may have a stress of 10 MPa or less when stretched at a stretch ratio of 200%.

[0078] When an electric current is passed through the stretchable ACF according to one embodiment of the present invention and the stretchable ACF is stretched at a stretch ratio of 80%, the relative current value according to the following formula (1) may be 0.8 or more and less than 1.05. That is, the stretchable ACF according to one embodiment of the present invention does not decrease in conductivity even when subjected to a stretching stimulus, and exhibits excellent conductivity stability. [Formula 1] Relative current = I / I0(1) In the above formula (1), I is the current measured in a state stretched at a stretch ratio of 80%, and I0 is the current measured in a state without stretching.

[0079] According to an embodiment of the present invention, there is provided a method for manufacturing an extensible Anisotropic Conductive Film (ACF), the method including the steps of: manufacturing a polymer film patterned with a pattern including protrusions and recesses; disposing conductive particles in the recesses of the patterned polymer film to obtain a polymer film in which the conductive particles are aligned; and hot-compressing the polymer film in which the conductive particles are aligned.

[0080] The method for producing stretchable ACF according to one embodiment of the present invention can provide ACF with excellent stretchability and conductivity.

[0081] Each step of the method will now be described in detail.

[0082] According to one embodiment of the present invention, a polymer film is first fabricated with a pattern including protrusions and recesses, which correspond to regions where conduction is required in a circuit when the stretchable ACF is used to attach a component such as a circuit board.

[0083] According to an embodiment of the present invention, the step of manufacturing the patterned polymer film is not particularly limited, and the patterned polymer film may be manufactured based on a method used in the imprint lithography technology field, examples of which will be described below, but are not limited thereto.

[0084] According to one embodiment of the present invention, the step of manufacturing the patterned polymer film includes the steps of manufacturing a reusable stamp and hot-compressing the reusable stamp with the polymer film to manufacture a polymer film patterned with a pattern including protrusions and recesses.

[0085] 2 is a schematic diagram of a method for manufacturing an expandable ACF according to an embodiment of the present invention. Referring to FIG. 2, a multi-use stamp 30 is hot-compressed with a polymer film to manufacture a patterned polymer film 60, conductive particles 10 are disposed in the recesses of the patterned polymer film 60, and the polymer film 60 with the aligned conductive particles is then hot-compressed to manufacture an expandable ACF 100.

[0086] According to an embodiment of the present invention, the step of manufacturing the reusable stamp is not particularly limited, and the reusable stamp may be manufactured based on a method used in the imprint lithography technical field, examples of which will be described below, but the present invention is not limited thereto.

[0087] Specifically, the step of manufacturing the reusable stamp includes the steps of coating a photoresist on a substrate and curing it to form a photoresist layer, positioning a photomask on the photoresist layer and irradiating it with light to form a patterned photoresist layer, further curing the patterned photoresist layer and immersing it in a developer to manufacture a mold, and using the mold to manufacture a reusable stamp having a pattern including protrusions and recesses.

[0088] First, a photoresist may be coated on a substrate and cured to form a photoresist layer, which is not particularly limited, and may be selected from the group consisting of silicon wafer, glass, indium tin oxide (ITO), and metal substrates such as gold, aluminum, copper, nickel, etc.

[0089] The photoresist may be any photoresist commonly used in the art, and may include, for example, a photosensitive resin. Preferably, the photoresist has a suitable level of processability for forming a columnar shape on a substrate, particularly a columnar shape having a ratio of column height to column diameter of 4 or more.

[0090] The method for coating the photoresist is not particularly limited, and the photoresist may be coated using a spin coating method to achieve a uniform coating. The coating may be performed once or twice or more times, and a thicker photoresist layer may be formed by coating multiple times.

[0091] The photoresist hardening process is performed by a first heat treatment step and a second heat treatment step, wherein the first heat treatment step may be performed at a temperature of 50°C to 70°C for 5 to 15 minutes, and the second heat treatment step may be performed at a temperature of 80°C to 100°C for 15 to 25 minutes.

[0092] A patterned photoresist layer can be formed by placing a photomask on the photoresist layer formed in this way and irradiating it with light. The photoresist may include a photosensitive resin, and an exposure process in which a photomask having a predetermined pattern is placed on the photoresist layer and light is irradiated causes deformation of the molecular structure of the photosensitive resin contained in the photoresist, resulting in differences in physical properties between the exposed and unexposed portions.

[0093] The photomask may include a pattern having a desired final shape. Specifically, light passing through the light-transmitting portions of the photomask deforms and photo-cures the molecular structure of the photoresist resin, while the photoresist layer below the light-impermeable portions of the photomask is not photo-cured because its molecular structure is not deformed by the light. That is, the photo-cured and un-photo-cured photoresist formed according to the shape of the pattern included in the photomask can form recesses and protrusions of the mold using a developer treatment, as described below.

[0094] The photomask may have a shape including a plurality of cells, and may have any one of a lattice shape, a honeycomb shape, a line shape, and a square shape, and the size of the cells may be larger than the diameter of the conductive particles, for example, more than 500 nm and less than or equal to 100 μm.

[0095] The step of forming the patterned photoresist layer may be performed by irradiating light having a wavelength of 300 nm to 400 nm, the light may be irradiated for 30 seconds to 50 seconds, and the irradiating power may be 20 mW / cm 2 ~40mW / cm 2 When light having a wavelength within this range is irradiated at an energy density within this range for a period of time within this range, the photoresist layer can be photoreacted smoothly, and in particular, the light-transmitting portion of the photomask can be photoreacted sufficiently.

[0096] According to an embodiment of the present invention, the patterned photoresist layer may be additionally cured by a first additional heat treatment step and a second additional heat treatment step, wherein the first additional heat treatment step may be performed at a temperature of 50°C to 70°C for 5 minutes to 15 minutes, and the second additional heat treatment step may be performed at a temperature of 80°C to 100°C for 15 minutes to 25 minutes.

[0097] The first additional heat treatment may be performed for a shorter time than the first heat treatment, and the second additional heat treatment may be performed for a shorter time than the second heat treatment.

[0098] The degree of hardening of the photo-hardened photoresist is increased through the additional hardening, and the photo-hardened photoresist is not dissolved or damaged in the development step described below.

[0099] According to one embodiment of the present invention, a mold can be manufactured by immersing the patterned photoresist layer after the additional curing in a developer. When the patterned photoresist layer is immersed in the developer, the uncured photoresist formed in the light-opaque portions of the photomask has a low degree of hardening and is removed by the developer. That is, the photocured photoresist formed by irradiating light through the light-transmitting portions of the photomask has a high degree of hardening and is not removed even when immersed in the developer, thereby forming convex portions of the mold, and the uncured photoresist formed in the light-opaque portions is removed by the developer, thereby forming concave portions of the mold.

[0100] The developer may be a solution commonly used in the art, and a solution appropriate for development may be used taking into account the type of photoresist. The developer may include an organic solvent capable of dissolving the photoresist.

[0101] According to one embodiment of the present invention, the patterned photoresist layer is developed by immersing it in a developer for 10 to 30 minutes, or 15 to 20 minutes. When development is performed for a time within this range, the step between the concave and convex portions of the mold is sufficiently defined to clearly define the pattern, thereby preventing the problem of the pattern becoming thin during the transfer process and allowing the multi-use stamp and patterned polymer film subsequently manufactured using the mold to have a step of an appropriate level for accurate placement of the conductive particles.

[0102] According to one embodiment of the present invention, the mold is manufactured based on the patterned photoresist layer, and the photoresist layer has recesses and protrusions formed based on the photomask. Therefore, the mold may have a shape including a plurality of cells, and may have any one of a lattice shape, a honeycomb shape, a linear shape, and a rectangular shape. Furthermore, the size of the cells may be larger than the diameter of the conductive particles, for example, greater than 500 nm and less than or equal to 100 μm.

[0103] According to an embodiment of the present invention, the mold may have pillars of photocured photoresist formed on a substrate, i.e., the convex portions of the mold may be pillars of photocured photoresist, and the concave portions of the mold may be spaces between the pillars of photocured photoresist.

[0104] According to one embodiment of the present invention, the mold may then be used to manufacture a reusable stamp including a pattern including protruding portions and recessed portions. The protruding portions and recessed portions may be formed in the mold as described above, with the protruding portions of the mold forming the recessed portions of the reusable stamp, and the recessed portions of the mold forming the recessed portions of the reusable stamp.

[0105] The step of manufacturing the reusable stamp includes the steps of pouring a prepolymer solution onto the mold and curing it to form a polymer pattern layer, and pouring a photocurable resin composition onto the polymer pattern layer and curing it to manufacture the reusable stamp.

[0106] The mold includes concave and convex portions having the same shape as the desired reusable stamp, but since the mold includes photoresist pillars formed on a substrate, the adhesive strength between the substrate and the photoresist pillars is low and the mold cannot be used as a reusable stamp. Therefore, a reusable stamp can be manufactured by the process described above.

[0107] The prepolymer solution may include, but is not limited to, PDMS, and may include silicone rubber, which has low surface energy and is easy to demold, i.e., separate from the mold, as used in the art. For example, commercially available products such as Ecoflex or Dragon Skin may be used.

[0108] The prepolymer solution may include a liquid phase prepolymer and may include one or more additives including a solvent, a crosslinker, an initiator, an antifoaming agent, and a chain extender.

[0109] The polymer pattern layer may be formed by curing the prepolymer solution at a temperature of 50° C. to 150° C. or 70° C. to 90° C. for 2 hours to 4 hours or 3 hours.

[0110] According to one embodiment of the present invention, a degassing process may be performed after the photocurable resin composition is poured onto the polymer pattern layer and before it is cured. Because the polymer pattern layer includes recesses with very narrow diameters, when the photocurable resin composition is poured onto the polymer pattern layer, a degassing process may be performed to remove gas present in the space between the photocurable resin composition and the recesses of the polymer pattern layer to prevent capillary development, which could cause the photocurable resin composition to not fully penetrate into the recesses of the polymer pattern layer. This allows the photocurable resin composition to deeply penetrate into the recesses of the polymer pattern layer, thereby forming a reusable stamp that has a similar shape to the polymer pattern layer.

[0111] The photocurable resin composition may contain a photocurable resin, but is not particularly limited and may contain any resin used in the art.

[0112] The cured product of the photocurable resin composition may have an appropriate modulus, for example, a Shore A hardness of more than 61 and less than 95.

[0113] The multi-use stamp is also configured to apply the photocurable resin composition at 196 mW / cm for 20 to 30 minutes. 2 ~134mW / cm 2 or 198mW / cm 2 ~132mW / cm 2 The resin composition may be produced by being cured by irradiating light at an energy density of 1000 kJ / cm 2 or more.

[0114] According to an embodiment of the present invention, the multi-use stamp is manufactured based on the mold, and therefore may have a shape including a plurality of cells, such as a lattice shape, a honeycomb shape, a linear shape, or a square shape. The size of the cells may be larger than the diameter of the conductive particles, for example, greater than 500 nm and less than or equal to 100 μm.

[0115] According to an embodiment of the present invention, the surface of the reusable stamp on which the recessed and protruding portions are formed may be surface-treated with silane. By treating the reusable stamp with silane, the reusable stamp can be easily separated after patterning the polymer film.

[0116] According to one embodiment of the present invention, the polymer film may be patterned with a pattern including protrusions and depressions by hot pressing the polymer film with the multi-use stamp prepared as described above. The multi-use stamp may be prepared as described above and have a pattern including protrusions and depressions.

[0117] The convex and concave portions of the reusable stamp may contact a soft polymer film, and the polymer film may be deformed and patterned into the pattern of the reusable stamp by thermocompression bonding. That is, the concave portions of the patterned polymer film may be formed by the convex portions of the reusable stamp, and the convex portions of the patterned polymer film may be formed by the concave portions of the reusable stamp.

[0118] According to one embodiment of the present invention, the polymer film is thermocompression bonded to a substrate, and the substrate may be surface-treated with silane on the surface on which the polymer film is formed. The substrate may be a slide glass, but is not particularly limited thereto. The silane surface treatment allows the manufactured expandable ACF to be easily removed.

[0119] According to one embodiment of the present invention, the polymer film may be prepared by coating and drying a solution containing 5% by weight to 20% by weight, 6% by weight to 20% by weight, 6% by weight to 12% by weight, 8% by weight to 12% by weight, or 6% by weight to 12% by weight of maleic anhydride-grafted heat-curable rubber. When the polymer film contains the maleic anhydride-grafted heat-curable rubber in an amount within the above range, the extensible ACF to be prepared can be manufactured to conform to the desired shape, resulting in excellent connectivity and conductivity when applied to devices, etc.

[0120] According to one embodiment of the present invention, the heat-curable rubber may be selected from styrene-ethylene-butylene-styrene (SEBS), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS), polyurethane (PU)-based rubber, and polyolefin (PO)-based rubber.

[0121] According to one embodiment of the present invention, the polymer film may have a thickness of 10 μm to 30 μm or 15 μm to 20 μm.

[0122] According to one embodiment of the present invention, the step of hot-compressing the reusable stamp with the polymer film may be performed at a temperature of 150°C to 200°C, 160°C to 200°C, 150°C to 190°C, 160°C to 190°C, 160°C to 180°C, or 170°C to 180°C for 5 to 20 minutes, 7 to 15 minutes, or 9 to 11 minutes. When hot-compression is performed at a temperature and pressure within the above ranges, the polymer film is smoothly patterned, a polymer film for an extensible ACF can be formed without damaging the reusable stamp, and the pressure can be uniformly distributed within the hot-compression region, allowing the film to be formed with an accurate pressure, thereby improving the accuracy of particle placement.

[0123] According to one embodiment of the present invention, the step of thermally compressing the multi-use stamp and the polymer film is performed by applying a pressure of 5 MPa to 20 MPa or 7.0 MPa to 15.7 MPa, but is not limited to this range and may be performed by applying a pressure sufficient to pattern the polymer film. The method of applying the pressure is also not particularly limited. For example, the stamp may be compressed by gravity using a weight, or permanent magnets may be positioned above and below the stamp to compress the film using magnetic force.

[0124] According to an embodiment of the present invention, the maximum difference in height between the protrusions and recesses of the patterned polymer film, i.e., the depth, may be 5 μm to 350 μm. When the difference in height is within this range, conductive particles can be accurately arranged in the recesses, as described below.

[0125] According to one embodiment of the present invention, the maximum difference in height between the protrusions and recesses of the patterned polymer film, i.e., the depth, may be 0.3 to 0.8 times, 0.5 to 0.8 times, 0.6 to 0.8 times, or 0.7 times the diameter of the conductive particles. When the maximum difference in height is within this range, the conductive particles are smoothly inserted into the recesses and do not easily slip out after being inserted, resulting in excellent process stability.

[0126] According to an embodiment of the present invention, the patterned polymer film is manufactured based on the multi-use stamp, and therefore may have a shape including a plurality of cells, such as a lattice shape, a honeycomb shape, a linear shape, or a square shape. The size of the cells may be larger than the diameter of the conductive particles, for example, greater than 500 nm and less than or equal to 100 μm.

[0127] According to one embodiment of the present invention, the recesses may be in the form of spaces formed by the protrusions, and the spaces may be larger than the diameter of the conductive particles. Specifically, the size, i.e., width, of the recesses in the patterned polymer film may be more than 1.0 times and less than 1.5 times the particle diameter. This allows the conductive particles to be accurately and stably arranged in the recesses, with one conductive particle per recess. By arranging the conductive particles in this manner, a polymer film in which the conductive particles are aligned can be obtained.

[0128] According to an embodiment of the present invention, conductive particles are disposed in the recesses of the patterned polymer film prepared as described above. The process of disposing the conductive particles is not particularly limited, and may be performed, for example, by the following method.

[0129] According to one embodiment of the present invention, the step of arranging the conductive particles may include the steps of: positioning a plurality of conductive particles on a part or all of the patterned polymer film; positioning an elastic member on the conductive particles at a distance from the patterned polymer film that is 1 to 10 times the diameter of the conductive particles; and reciprocating the patterned polymer film in one direction for a predetermined distance one or more times, so that the elastic member inserts the conductive particles into the recesses of the patterned polymer film.

[0130] First, a plurality of conductive particles may be disposed on a part or all of the patterned polymer film, specifically, on a surface of the patterned polymer film on which a pattern including concave and convex portions is formed.

[0131] The conductive particles are as described above.

[0132] The particle disposing step is a dry process and can be applied to disposing conductive particles of various sizes.

[0133] Next, an elastic member may be positioned on the conductive particles at a distance from the patterned polymer film that is 1 to 10 times, 1 to 5 times, 1 to 2 times, or 1.5 times the diameter of the conductive particles. The elastic member serves to support the conductive particles, and more specifically, to directly contact the conductive particles and rub the pattern including the recesses and protrusions formed on the polymer film.

[0134] The elastic member may be made of PDMS (polydimethylsiloxane), PUA (polyurethane acrylate), PMMA (polymethyl methacrylate), PB (polybutadiene), PU (polyurethane), SBR (styrene-butadiene rubber), PVDF (polyvinylidene fluoride), PVDF-TrFE (poly(vinylidene fluoride-co-trifluoroethylene)), PS (polystyrene), SBS-PEDGA (poly(ethylene glycol) diacrylate), SBS (ploy(styrene-butadiene-styrene)), SEBS (poly(styreneethylene-butylene-styrene)), SIS (poly(styrene-isoprene-styrene)), or the like, but is preferably PDMS.

[0135] Next, the patterned polymer film may be reciprocated in one direction for a predetermined distance once or multiple times, allowing the elastic member to insert the conductive particles into the recesses of the patterned polymer film.

[0136] The patterned polymer film is placed on a moving member and moved, and the moving member may be a conveyor belt.

[0137] When the belt moves and is deformed into a ⊂ or ⊃ shape, the patterned polymer film on the belt is correspondingly deformed into a ⊂ or ⊃ shape, and the conductive particles can be arranged continuously and over a large surface.

[0138] Preferably, a portion of the patterned polymer film is moved using the moving member, and the patterned polymer film is moved back and forth in one direction a predetermined distance once or multiple times, so that the conductive particles are inserted into recesses in another portion of the patterned polymer film, and the above steps can be repeated multiple times as necessary.

[0139] Through the above process, conductive particles can be aligned in the recesses of the patterned polymer film.

[0140] According to one embodiment of the present invention, a polymer film with aligned conductive particles can be obtained through the above process and then hot-compressed to manufacture an extensible ACF. The conductive particles are aligned in the recesses of the polymer film, and when the polymer film is hot-compressed, the polymer film is deformed and fills the pores between the conductive particles and the polymer film, thereby manufacturing an extensible ACF in which the conductive particles are firmly inserted into the polymer film.

[0141] According to one embodiment of the present invention, the step of hot-compressing the polymer film with aligned conductive particles may be performed at a temperature of 100°C to 300°C, 130°C to 300°C, 100°C to 280°C, 130°C to 280°C, 130°C to 250°C, 130°C to 235°C, 130°C to 200°C, 180°C to 235°C, or 235°C to 280°C for 1 hour to 4 hours or 2 hours. When hot-compression is performed at a temperature and time within the above ranges, the polymer is appropriately deformed to adhere to the conductive particles, and all polymer remaining on the exposed surfaces of the conductive particles is removed, thereby reducing contact resistance. The temperature and duration of the hot-compression step may be adjusted depending on the type of thermosetting rubber contained in the polymer film.

[0142] According to an embodiment of the present invention, the step of hot-compressing the polymer film with the aligned conductive particles may be performed by applying a pressure of 50 MPa to 150 MPa or 57.1 MPa to 128 MPa, but is not limited to this range and may be performed by applying a pressure sufficient to adequately deform and adhere the polymer film and the conductive particles. In addition, there is no particular limitation on the method of applying the pressure.

[0143] According to one embodiment of the present invention, fever The method may further include a step of treating one or both surfaces of the expandable ACF with oxygen plasma after the squeezing step, which increases the surface energy of the expandable ACF and makes the surface relatively hydrophilic, thereby improving the interfacial adhesion with other members.

[0144] The expandable ACF manufactured by the method according to one embodiment of the present invention may have an alignment retention of 0.8 to 1.0. The "alignment retention" refers to the number of conductive particles per unit area after secondary thermocompression bonding relative to the number of conductive particles per unit area before secondary thermocompression bonding, and can be expressed by the following formula (2): [Formula 2] Alignment maintenance rate = N / N0 In the formula (2), N is the number of conductive particles per unit area after the second thermocompression bonding, and N0 is the number of conductive particles per unit area before the second thermocompression bonding.

[0145] During the secondary thermocompression, the polymer film melts, reducing the number of conductive particles per unit area, and if an excessive amount of polymer melts, the final ACF may have a shape different from the desired shape of the stretchable ACF.

[0146] When the degree of alignment retention is within the above range, the stretchable ACF to be manufactured can be manufactured to match the desired shape, resulting in excellent connectivity and conductivity when applied to devices, etc., and the electrical resolution of the ACF can be improved because the conductive particles do not aggregate. Furthermore, since the stretchable ACF can be manufactured while maintaining the alignment before thermocompression bonding, the width of the wiring, etc., for using the stretchable ACF as an adhesive member can be calculated in advance and the stretchable ACF can be manufactured to fit the corresponding circuit.

[0147] According to one embodiment of the present invention, there is provided an interfacial bonding material comprising the extensible ACF, which can be interposed between soft and soft materials or between soft and hard materials to firmly bond the interface.

[0148] According to one embodiment of the present invention, there is provided a device including at least one of an electrode and an electronic component and the interface bonding member. The device can be applied in various forms within the scope of the technical field to the semiconductor industry, display industry, etc.

[0149] According to one embodiment of the present invention, the element may include one or more of an electrode and an electronic component. Specifically, the element may include one or more electrodes, one or more electronic components, or one or more electrodes and one or more electronic components.

[0150] According to an embodiment of the present invention, the electronic component may include one or more of an active element and a passive element. The active element may include electronic components forming an integrated circuit such as a driver chip, a light emitting element, and a memory element. The electronic component may also be a wiring.

[0151] According to an embodiment of the present invention, the electrode may include a substrate on which a conductive material layer is formed, The substrate may be an insulating material such as a polymeric substrate, and the conductive material layer may include a metal such as gold.

[0152] According to one embodiment of the present invention, the interface bonding member may bond between electrodes when the element includes one or more of the electrodes, or may bond between electronic components when the element includes one or more of the electronic components, or may bond between electrodes, between electronic components, and between electrodes and electronic components when the element includes one or more of both the electrodes and the electronic components.

[0153] When an interface bonding member including an expandable ACF according to one embodiment of the present invention is bonded to a wiring, the number of conductive particles in contact with the wiring may vary depending on the shape of the wiring, and electrical connection may not be ensured. Therefore, according to one embodiment of the present invention, the expandable ACF may be bonded to a wiring having a width that can include at least one particle.

[0154] FIG. 4 is a schematic diagram for calculating the minimum width of a wiring in a form in which conductive particles are arranged in an expandable ACF according to an embodiment of the present invention.

[0155] Specifically, if the radius of the conductive particles is a and the spacing between the outer surfaces of the conductive particles is b, if the wiring is arranged at 45° to the conductive particle arrangement as shown in the red shading, the wiring must have a width of at least 3.41a+0.71b to ensure electrical connection; if the wiring is arranged at 0° to the conductive particle arrangement as shown in the blue shading, the wiring must have a width of at least 4a+b to ensure electrical connection.

[0156] The minimum width of the wiring may be calculated differently depending on the arrangement of the conductive particles, the size of the conductive particles, and the spacing between the conductive particles, and the conductivity of the expandable ACF according to an embodiment of the present invention may be ensured for a circuit having such a minimum width.

[0157] According to an embodiment of the present invention, the substrate may be a flexible substrate or a stretchable substrate. A flexible substrate is a substrate whose shape changes when subjected to an external force but whose dimensions do not change, while a stretchable substrate is a substrate whose shape changes when subjected to an external force but whose dimensions also change.

[0158] According to one embodiment of the present invention, at least one of the electrodes and the electronic component may have a hydrophilic surface treatment applied to a surface that comes into contact with the interface bonding member.

[0159] According to one embodiment of the present invention, the hydrophilic surface treatment is oxygen plasma treatment. When the surface of the electrode and / or substrate is treated with oxygen plasma, hydroxyl groups are introduced onto the surface, improving the surface energy, which allows chemical bonding with the expandable ACF to be formed, improving the bonding strength.

[0160] According to one embodiment of the present invention, the hydrophilic surface treatment may use a silane compound, which may include one or more of a thiol group, an amine group, a glycidyl group, a hydroxy group, a carboxyl group, a vinyl group, a phosphonic acid group, an anhydride group, a methacrylic acid group, an isocyanate group, an aldehyde group, a cyano group, an azide group, an ester group, and a halogen substituent. When a silane compound including the above-listed functional groups is used, the hydrophilic functional group forms a chemical bond with the polymer film, thereby improving the adhesive strength between the expandable ACF and the electrode or the substrate.

[0161] According to one embodiment of the present invention, when at least one of the electrodes and the electronic component is subjected to a hydrophilic surface treatment on the surface in contact with the interface bonding member, the electrode and the electronic component can be bonded to the extensible ACF by simple compression even at low temperatures of about 50°C to 100°C through chemical bonding. Therefore, excellent bonding stability can be achieved without dissolving the polymer film or causing the conductive particles to move. Furthermore, the compression may be performed at a pressure of 0.1 MPa or more, but is not limited to this range. The method of applying the pressure is also not particularly limited; for example, the components may be directly squeezed by hand.

[0162] Hereinafter, in order to specifically explain the present invention, embodiments will be described in detail. However, the embodiments according to the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments in this specification are provided to more completely explain the present invention to those having average knowledge in the art.

[0163] [Materials used] SU-8 50: Microchem, USA (photoresist) Polydimethylsiloxane prepolymer: Dow Corning, USA Sylgard 184: Dow Corning, USA (crosslinking agent) NOA61: Norland Products, Inc., USA Styrene-ethylene-butylene-styrene grafted with maleic anhydride (SEBS-g-MA, MA content 2 wt% or less): Sigma-Aldrich Trichloro(octadecyl)silane (OTS, molecular weight 387.93 g / mol): Sigma-Aldrich Chloroform (99.5%): Samcheong Chemical Co., Ltd., Korea Toluene (99.8%): Samcheong Chemical Co., Ltd., Korea Gold-coated conductive microparticles (diameter 3.25 μm): Deoksan Co., Korea Polyimide film (thickness 50 μm) (3-Mercaptopropyl)trimethoxysilane (MPTMS, 95%): Sigma-Aldrich (3-Aminopropyl)triethoxysilane (APTES, 99%): Sigma-Aldrich (3-Glycidyloxypropyl)trimethoxysilane (GPTMS, 98%): Sigma-Aldrich [Embodiment 1] [Manufacturing of multi-use stamps] After cleaning and drying, a native Si wafer was cut into a 2.5 cm x 2.5 cm piece. SU-8 50 photoresist was spin-coated onto the Si wafer at 500 rpm for 10 seconds and then at 2000 rpm for 30 seconds. It was then heat-treated twice: at 65°C for 10 minutes and at 95°C for 20 minutes. A photomask was then placed on top of it, and the resist was irradiated with 365 nm light at 30 mW / cm for 3 and 6 seconds. 2 The sample was exposed to ultraviolet light for 100 s.p.m.

[0164] The slightly cross-linked photoresist was then heat-treated at 65°C for 9 minutes and 95°C for 12 minutes, and then immersed in a developer to remove the unexposed SU-8 prepolymer.The mold was then obtained by rinsing with IPA and removing the solution by evaporation at 80°C.

[0165] Liquid-phase PDMS (prepolymer and crosslinker weight ratio 10:1) was poured onto the mold and cured at 80°C for 3 hours. Afterwards, NOA61 was poured onto the cured polymer pattern layer, and the NOA61 prepolymer was degassed to overcome capillary forces. Uncured NOA61 on the polymer pattern layer was applied at 132 mW / cm for 20 minutes. 2 After UV exposure, the polymer pattern layer was peeled off and washed with toluene. A 2 wt% OTS solution in toluene was spin-coated onto the oxygen plasma-treated NOA61 stamp to fabricate a multi-use stamp.

[0166] [Production of Expandable ACF] An 8 wt% SEBS-g-MA solution in chloroform was spin-coated onto a PDMS film at 3000 rpm for 60 min, and the solvent was evaporated at 80°C for 10 min. The SEBS-g-MA thin film (thickness: ∼17 μm) was separated from the PDMS film and placed on an OTS-treated slide glass. The patterned polymer film was then hot-pressed at 180°C for 10 min under vacuum using the multi-use stamp prepared above.

[0167] Next, Au / Ni / PS microparticles (diameter ~20μm) were rubbed onto the patterned polymer film with a small piece of PDMS. The polymer film with aligned conductive particles and patterned was then sandwiched between PDMS and a glass slide and hot-pressed at 235℃ for 2 hours in a vacuum to obtain a stretchable ACF containing deformed MPs (thickness ~13μm).

[0168] [Embodiment 2] An expandable ACF was obtained in the same manner as in Example 1, except that the patterned polymer film with aligned conductive particles was placed between PDMS and a slide glass, and hot-pressed at 180°C for 2 hours under vacuum.

[0169] [Embodiment 3] An expandable ACF was obtained in the same manner as in Example 1, except that the patterned polymer film with aligned conductive particles was placed between PDMS and a slide glass, and hot-pressed at 130°C for 2 hours under vacuum.

[0170] [Embodiment 4] Expansion ACF was obtained in the same manner as in Example 1, except that a 6 wt % SEBS-g-MA solution in chloroform was used.

[0171] [Embodiment 5] Expansion ACF was obtained in the same manner as in Example 1, except that a 12 wt % SEBS-g-MA solution in chloroform was used.

[0172] [Reference example 1] An 8 wt% SEBS-g-MA solution in chloroform was spin-coated onto the PDMS film at 3,000 rpm for 60 min, and the solvent was evaporated at 80 °C for 10 min. A polymer film was fabricated by separating the SEBS-g-MA thin film (thickness ∼17 μm) from the PDMS film.

[0173] [Reference example 2] The patterned polymer film with aligned conductive particles manufactured in Example 1 was prepared without performing a separate thermocompression process.

[0174] [Test Example 1: Observation of SEM and OM images] In the first embodiment, a SEM image of a cross section of the polymer film on which the conductive particles were aligned and patterned was taken using an FE-SEM (S-2400, Hitachi) under conditions of 25 kV and 1.2 k magnification.

[0175] FIG. 5 is an SEM image of a cross section of a polymer film in which conductive particles are aligned and patterned according to the first embodiment.

[0176] Referring to FIG. 5, it can be seen that the polymer film is patterned with a pattern including recesses and protrusions, and that conductive particles are arranged and aligned in the recesses of the pattern.

[0177] In addition, a SEM image of the cross section of the expandable ACF manufactured in the first embodiment was taken using the same equipment, FE-SEM (S-2400, Hitachi) under the conditions of 25 kV and 1.5 k magnification.

[0178] FIG. 6 is an SEM image of the cross section of the expandable ACF produced in the first embodiment.

[0179] Referring to FIG. 6, conductive particles contained in the polymer film can be seen. The conductive particles are spherical as seen in FIG. 5, and are deformed by thermocompression bonding to expose the top and bottom.

[0180] An optical microscope (OM) image of the surface of the stretchable ACF prepared in Example 1 was taken using an Olympus BX-51 in reflection mode at 200x magnification. After the stretchable ACF prepared in Example 1 was uniaxially stretched 100% in the transverse direction, an OM image of the surface was taken under the same conditions.

[0181] 7A and 7B each show an OM image of the surface of the expandable ACF produced in Example 1.

[0182] 7A and 7B, it can be seen that the stretchable ACF prepared in embodiment 1 has excellent structural stability and durability, as the polymer film is not broken or particles are not shed even when stretched.

[0183] [Test Example 2: Mechanical properties of stretchable ACF] The stretchable ACFs of Examples 1 to 3 and the films of Reference Examples 1 and 2 were cut to a size of 5 mm x 30 mm and fixed on both sides to a tensile tester with polyimide adhesive tape. A tensile tester (T95-PE, LINKAM SCIENTIFIC INSTRUMENTS LTD, UK) was used to obtain stress-strain curves under the following conditions: the thickness of the stretched ACP was 13 μm and the size was 5 mm x 5 mm. The pulling speed was 50 μm / s and the initial distance was 5 mm.

[0184] FIG. 8 shows the stress-strain curves of the stretchable ACFs of Examples 1 to 3 and the films of Reference Examples 1 and 2.

[0185] 8, it can be seen that the stretchable ACFs of Embodiments 1 to 3 have excellent stretchability, with stress of less than 10 MPa at a stretch ratio of 100%. In particular, it can be seen that the stretchable ACF of Embodiment 1, which was produced by hot-compressing at the highest temperature, had the lowest stress and was therefore excellent in stretchability.

[0186] Test Example 3: Measurement of connection resistance and alignment maintenance For the 4-probe measurement, gold circuit lines with a width of 1 mm and a thickness of 60 nm were fabricated using a thermal evaporator (Terraleader Co., Ltd., Korea) with a PET shadow mask on an MPTMPS-treated PI film. The ACF fabricated in Examples 1, 4, and 5 was laminated on the fabricated gold circuit lines, and 4-probe measurements were performed using a Keithley 2450. The connection resistance was calculated as the measurement result. The connection resistance was also measured under the same conditions using a direct connection using liquid metal (ref).

[0187] Furthermore, the number of particles in the ACFs manufactured in the first, fourth and fifth embodiments was observed using an optical microscope before and after thermocompression bonding, and the degree of alignment maintenance was calculated using the above formula.

[0188] FIG. 9 is a graph showing the connection resistance and alignment retention of the ACFs produced in the first, fourth, and fifth embodiments.

[0189] 9, it can be seen that the expandable ACF prepared in embodiment 1 has excellent effects, such as low connection resistance and high alignment retention. In addition, in the case of the expandable ACF prepared in embodiment 4, it can be seen that the polymer content is low, and therefore there are both wide and narrow areas where the conductive particles are exposed during the thermocompression process, resulting in an uneven connection resistance and a somewhat wide scale bar.

[0190] [Test Example 4: Observation of ACF surface depending on polymer content] The surfaces of the expandable ACFs manufactured in Examples 1, 4, and 5 were photographed as OM images using an Olympus BX-51 in reflection mode at 50x magnification.

[0191] 10A to 10C are surface OM images of the expandable ACFs produced in Examples 1, 4, and 5, respectively.

[0192] 10A to 10C, it can be seen that the expandable ACF manufactured in the first embodiment has the most uniformly arranged conductive particles.

[0193] Test Examples 3 and 4 show that the expandable ACF of embodiment 1, which has a polymer content of 8 wt %, is preferable because the conductive particles are uniformly arranged and the connection resistance is low.

[0194] Test Example 5: Evaluation of electrical properties of expandable ACF After covering the polyimide film with a SUS shadow mask, 100 μm wide gold lines were vapor-deposited using an evaporator to form wires 1 and 2. The extensible ACF prepared in embodiment 1 was then laminated between wires 1 and 2, and hot-pressed at 230°C for 1 to 2 hours. The surface of the resulting laminate was photographed with an Olympus BX-51 OM imager in reflective mode at 50x magnification.

[0195] FIG. 11 is an OM image taken on the top surface of a laminate containing the expandable ACF produced in the first embodiment.

[0196] 11, it can be seen that the expandable ACF (the area where conductive particles are aligned) is located between Wire 1 (the dark pink solid line) and Wire 2 (the black dotted line). Also shown are the gold lines of Wire 1 and Wire 2 connected via the expandable ACF (A1-A2 (not shown), B1-B2, C1-C2, D1-D2, E1-E2).

[0197] In the laminate thus produced, a bias of 0 V and 1.5 V was applied between the metal lines of Wiring 1 and Wiring 2, and the flowing current was measured using a Keithley 2400.

[0198] 12 is a graph showing the results of testing the electrical performance of the laminate of Test Example 5. Specifically, the graph shows the current value versus bias of the laminate for each connection line.

[0199] It was confirmed that high conductivity connection was possible through the ACF for the connection lines A1-A2, B1-B2, C1-C2, D1-D2, and E1-E2 of the stacked wiring 1 and wiring 2, and no current was measured in the separated A1-B2 line. As a result, it was confirmed that perfect bi-isotropic conduction was achieved through the fabricated ACF.

[0200] [Production Example 1] The polyimide film was washed with acetone, ethanol, and deionized water, then treated with oxygen plasma. A (3-mercaptopropyl)trimethoxysilane solution was vapor-deposited under vacuum for two hours to deposit the target molecules. The self-assembled membrane (SAM)-treated substrate was then washed and dried at 80°C to produce a surface-treated substrate.

[0201] [Production Example 2] A surface-treated substrate was prepared in the same manner as in Preparation Example 1, except that a (3-aminopropyl)triethoxysilane solution was used.

[0202] [Production Example 3] A surface-treated substrate was prepared in the same manner as in Preparation Example 1, except that a (3-glycidyloxypropyl)triethoxysilane solution was used.

[0203] [Embodiment 6] The stretchable ACF produced in Embodiment 1 was placed between two of the surface-treated substrates produced in Production Example 1 so that the surface-treated surfaces were in contact with each other, and the substrates were hot-compressed for 1 hour to produce a laminate.

[0204] [Embodiment 7] The stretchable ACF produced in Embodiment 1 was placed between two of the surface-treated substrates produced in Production Example 2 so that the surface-treated surfaces were in contact with each other, and the substrates were hot-compressed for 1 hour to produce a laminate.

[0205] [Embodiment 8] The stretchable ACF produced in Embodiment 1 was placed between two of the surface-treated substrates produced in Production Example 3 so that the surface-treated surfaces were in contact with each other, and the substrates were hot-compressed for 1 hour to produce a laminate.

[0206] [Reference example 3] A purchased double-sided tape for wig attachment (TT044) from 3M was placed between two of the surface-treated substrates prepared in Preparation Example 3 so that the treated surfaces were in contact with each other, and the substrates were hot-pressed for 1 hour to prepare a laminate.

[0207] [Reference example 4] A polystyrene-block-poly(ethylene-random-butylene)-block-polystyrene film purchased from Sigma-Aldrich was placed between two of the surface-treated substrates prepared in Preparation Example 3 with the treated surfaces facing each other, and the substrates were hot-pressed for 1 hour to prepare a laminate.

[0208] [Test Example 6: Confirmation of bonding characteristics] In a T-peel off test, two substrates of the laminates produced in Examples 6 to 8 and Reference Examples 3 and 4 were separated, and the adhesive strength was measured when the distance between the substrates was 1 cm.

[0209] FIG. 13 shows a graph of adhesive strength as a function of distance for the laminates produced in Examples 6 to 8 and Reference Examples 3 and 4. In FIG.

[0210] 13, it is confirmed that the laminate of embodiment 7 has the strongest adhesive strength, and the laminate of embodiment 6 has the second strongest adhesive strength. In other words, it is confirmed that when the surface of the substrate is surface-treated with silane having a hydrophilic group, the bonding strength is strong.

[0211] [Production Example 4] A 200µm thick, 60nm wide gold line was formed on a polyimide film washed with acetone, ethanol, and deionized water using a thermal evaporator through a SUS shadow mask, and the target molecules were deposited by vapor deposition of (3-aminopropyl)triethoxysilane solution for 2 hours under vacuum. The self-assembled monolayer (SAM)-treated substrate was washed and dried at 80°C to produce a surface-treated electrode including a flexible substrate.

[0212] [Production Example 5] A 200 μm wide EGaIn liquid metal line was embedded on the PDMS film, and the surface on which the liquid metal line was formed was treated with oxygen plasma to fabricate an electrode including a stretchable substrate.

[0213] [Embodiment 9] The expandable ACF manufactured in Embodiment 1 was placed between two electrodes manufactured in Manufacturing Example 4 so that the surface on which the gold lines were formed was in contact with the electrodes, and the ACF was compressed at a temperature of 80°C for 1 hour to manufacture a laminate measuring 5 mm x 10 mm.

[0214] [Embodiment 10] The stretchable ACF manufactured in Embodiment 1 was interposed between the electrode manufactured in Manufacturing Example 4 and the electrode manufactured in Manufacturing Example 5 so that the surface of the electrode on which the gold lines were formed and the surface on which the metal lines were formed were in contact with each other, and the electrodes were pressed at a temperature of 80°C for 1 hour to manufacture a 5 mm x 10 mm laminate.

[0215] [Embodiment 11] The expandable ACF prepared in Embodiment 1 was placed between two electrodes prepared in Preparation Example 5 so that the surface on which the metal lines were formed was in contact with the electrodes, and the ACF was compressed at a temperature of 80°C for 1 hour to prepare a laminate measuring 5 mm x 10 mm.

[0216] [Test Example 7: Confirmation of electrical characteristics for various substrates] The laminate of Example 9 was subjected to different pressures over time, and the current value was measured when 1 V was applied using a Keitheley 2400.

[0217] The laminates of Examples 10 and 11 were stretched in one direction at different stretch ratios depending on the time, and the current value was measured when 1 V was applied using a Keitheley 2400.

[0218] The measured current was divided by the current value I0 when no pressure or stretching was applied and shown as a relative current.

[0219] FIG. 14 is a graph showing the pressure and relative current over time applied to the laminate of embodiment 9, and FIGS. 15 and 16 are graphs showing the stretching and relative current over time applied to the laminates of embodiments 10 and 11, respectively.

[0220] Referring to FIG. 14, it can be seen that stable interfacial connection is achieved even in the presence of external pressure due to chemical bonding between maleic acid groups contained in the polymer film of the stretchable ACF manufactured in embodiment 1 and amine groups on the surface of the flexible substrate. Referring to FIG. 15, it can be seen that stable interfacial connection is achieved even when stretched up to 20% by external force due to chemical bonding between maleic acid groups contained in the polymer film of the stretchable ACF manufactured in embodiment 1 and amine groups on the surface of the flexible substrate and hydroxyl groups on the surface of the stretchable substrate. Referring to FIG. 16, it can be seen that stable interfacial connection is achieved with almost no change in current even when stretched up to 80% by external force due to chemical bonding between maleic acid groups contained in the polymer film of the stretchable ACF manufactured in embodiment 1 and hydroxyl groups on the surface of the stretchable substrate.

[0221] Although the present invention has been described above using limited embodiments, the present invention is not limited thereto, and various modifications and variations may be made by a person skilled in the art to which the present invention pertains within the technical spirit of the present invention and the scope of equivalents of the claims set forth below.

[0222] [Explanation of symbols] 100: Stretchable ACF 10: Conductive particles 20: Polymer film 30: Multi-use stamp 41, 42: Base material 50: Silane surface treatment layer 60: Patterned polymer film 70: Elastic member [Brief explanation of the drawings]

[0223] [Figure 1] FIG. 1 is a schematic diagram of a stretchable ACF film according to one embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram of a method for producing expandable ACF according to one embodiment of the present invention. [Figure 3] FIG. 1 is a schematic diagram illustrating the case where conductive particles of an expandable ACF according to one embodiment of the present invention function as a conductive path. [Figure 4] 1 is a schematic diagram for calculating the minimum width of connectable wiring in a form in which conductive particles of an expandable ACF according to an embodiment of the present invention are arranged. FIG. [Figure 5] 1 is an SEM image of a cross section of a patterned polymer film in which conductive particles are aligned according to embodiment 1. [Figure 6] 1 is an SEM image of the cross section of the expandable ACF produced in embodiment 1. [Figure 7A] 1 shows an OM image of the surface of the expandable ACF produced in embodiment 1. [Figure 7B] 1 shows an OM image of the surface of the expandable ACF produced in embodiment 1. [Figure 8] 1 shows stress-strain curves for the stretchable ACFs of Embodiments 1 to 3 and the films of Reference Examples 1 and 2. [Figure 9] 1 is a graph showing the connection resistance and alignment retention of ACFs produced in embodiments 1, 4, and 5. [Figure 10A] 1A and 1B are surface OM images of the expandable ACFs produced in embodiments 1, 4, and 5, respectively. [Figure 10B] 1A and 1B are surface OM images of the expandable ACFs produced in embodiments 1, 4, and 5, respectively. [Figure 10C] 1A and 1B are surface OM images of the expandable ACFs produced in embodiments 1, 4, and 5, respectively. [Figure 11]1 is an OM image taken on the top surface of a laminate containing the expandable ACF produced in embodiment 1. [Figure 12] 10 shows the results of testing the electrical performance of the laminate of Test Example 5. [Figure 13] 1 is a graph showing the adhesive strength of laminates produced in Examples 6 to 8 and Reference Examples 3 and 4 as a function of distance. [Figure 14] 13 is a graph showing pressure and relative current over time applied to a laminate of Example 9. [Figure 15] 10 is a graph showing the stretch over time and relative current applied to laminates of embodiments 10 and 11, respectively. [Figure 16] 10 is a graph showing the stretch over time and relative current applied to laminates of embodiments 10 and 11, respectively.

Claims

1. The conductive film includes a polymer film and conductive particles inserted and aligned in the polymer film, The conductive particles are exposed on the outer surfaces of the upper and lower polymer films, The spacing between the conductive particles is 10 μm to 400 μm; A method for producing an expandable ACF, in which 10% to 30% of the outer surface of the conductive particles is exposed to the outside of the polymer film, comprising: A step of manufacturing a polymer film patterned with a pattern including protrusions and recesses; disposing conductive particles in the recesses of the patterned polymer film to obtain a polymer film in which the conductive particles are aligned; hot-compressing the polymer film in which the conductive particles are aligned; Including, The step of disposing conductive particles includes: disposing a plurality of conductive particles on some or all of the patterned polymer film; positioning an elastic member over the conductive particles at a separation distance from the patterned polymer film of 1 to 10 times the diameter of the conductive particles; and moving the patterned polymer film back and forth in one direction once or multiple times for a predetermined distance, so that the elastic member inserts the conductive particles into the recesses of the patterned polymer film.

2. The step of manufacturing the patterned polymer film includes: manufacturing a multi-use stamp; hot-compressing the multi-use stamp with a polymer film to produce a polymer film patterned with a pattern including protrusions and recesses; The method for producing the expandable ACF of claim 1, comprising:

3. The step of manufacturing the multi-use stamp includes: coating and curing a photoresist on a substrate to form a photoresist layer; placing a photomask on the photoresist layer and irradiating it with light to form a patterned photoresist layer; further hardening the patterned photoresist layer and immersing it in a developer to produce a mold; manufacturing a multi-use stamp including a pattern including protruding portions and recessed portions using the mold; The method for producing the expandable ACF according to claim 2, comprising:

4. The method for producing extensible ACF according to claim 2, wherein the polymer film is produced by coating and drying a solution containing 5% by weight to 20% by weight of maleic anhydride-grafted heat-curable rubber.

5. The method for producing an expandable ACF according to claim 2, wherein the step of hot-compressing the multi-use stamp with the polymer film is performed at a temperature of 150°C to 200°C for 5 minutes to 20 minutes.

6. 3. The method for producing a stretchable ACF according to claim 2, wherein the recesses of the patterned polymer film are formed by protrusions of the reusable stamp, and the protrusions of the patterned polymer film are formed by recesses of the reusable stamp.

7. 2. The method for manufacturing an expandable ACF according to claim 1, wherein the step of hot-compressing the polymer film in which the conductive particles are aligned is performed at a temperature of 100° C. to 300° C. for 1 hour to 4 hours.

8. The method for producing the expandable ACF according to claim 1 , further comprising the step of surface treating one or both surfaces of the expandable ACF with oxygen plasma after the hot-compressing step.

9. An element including at least one of an electrode and an electronic component, and an interface bonding member, the interface bonding member includes an expandable ACF, The expandable ACF includes a polymer film and conductive particles inserted and aligned in the polymer film, The conductive particles are exposed on the outer surfaces of the upper and lower polymer films, The spacing between the conductive particles is 10 μm to 400 μm; 10% to 30% of the outer surface of the conductive particles is exposed to the outside of the polymer film; At least one of the electrodes and the electronic component has a hydrophilic surface treatment applied to the surface that contacts the interface bonding member.

10. 10. The device of claim 9, wherein the hydrophilic surface treatment is an oxygen plasma treatment.

11. 10. The device according to claim 9, wherein the hydrophilic surface treatment uses a silane compound.

12. 12. The device of claim 11, wherein the silane compound comprises one or more of a thiol group, an amine group, a glycidyl group, a hydroxy group, a carboxyl group, a vinyl group, a phosphonic acid group, an anhydride group, a methacrylic acid group, an isocyanate group, an aldehyde group, a cyano group, an azide group, an ester group, and a halogen substituent.

13. An element including at least one of an electrode and an electronic component, and an interface bonding member, the interface bonding member includes an expandable ACF, The expandable ACF includes a polymer film and conductive particles inserted and aligned in the polymer film, The conductive particles are exposed on the outer surfaces of the upper and lower polymer films, The spacing between the conductive particles is 10 μm to 400 μm; 10% to 30% of the outer surface of the conductive particles is exposed to the outside of the polymer film; The electronic component includes at least one of an active element and a passive element.

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