Filler array film and method for manufacturing same, and connection structure and method for manufacturing same

Abstract

To provide a structure which does not require individualization by a laser lift-off method and can be formed by using a simple transfer mold to the filler array film required for the creation, when creating a μLED display using a filler array film that can function as an anisotropic conductive film.SOLUTION: The filler array film has a filler-retaining insulating resin layer and a filler, wherein recesses and protrusions are formed on one surface of the filler-retaining insulating resin layer, and at least one filler group composed of a plurality of fillers is arranged on the protrusions. The protrusions are preferably regularly arranged. In the filler group, a plurality of fillers are preferably regularly arranged. It is preferable that no filler is disposed in the recesses.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a filler-arranged film and a manufacturing method thereof, and a connection structure and a manufacturing method thereof. [Background technology]

[0002] In recent years, displays in which self-luminous μLEDs (micro light-emitting diodes) are mass-transferred onto a display wiring board and arranged in a matrix are attracting attention as next-generation displays for relatively small smartphone displays, relatively large TV displays, and signage displays. μLEDs usually have a pair of electrodes arranged on one side, but they are microelectronic components with a fine pitch that results in an extremely narrow space between the electrodes.

[0003] As methods for connecting such tiny μLEDs to a wiring board, methods such as solder reflow and eutectic methods have difficulty dealing with the fine pitch of μLEDs at the electrode level, and it is also difficult to uniformly and reliably mass-transfer a huge number of μLEDs. Therefore, conductive connection methods using conductive films, which are a type of filler array film that can handle both fine pitch and mass transfer, and anisotropic conductive connection methods using anisotropic conductive films are attracting much attention.

[0004] For example, as an anisotropic conductive film applicable to μLEDs, a film has been proposed in which a group of conductive particles consisting of a plurality of conductive particles is regularly arranged at a distance from each other over the entire surface of an insulating resin sheet (Patent Document 1), and a filler array film that can function as an anisotropic conductive film diced into microLED-sized pieces by the so-called laser lift-off method (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-103476 A [Patent Document 2] JP 2022-151822 A Summary of the Invention [Problem to be solved by the invention]

[0006] By the way, in the case of the anisotropic conductive film of Patent Document 1, it is necessary to prepare a transfer mold in advance for transferring the conductive particle group consisting of a plurality of conductive particles to the wiring board in correspondence with the μLED, but when the regular arrangement pattern of the μLED of the μLED display to which the anisotropic conductive film is to be applied changes, a new transfer mold must be prepared each time. Moreover, even in that case, even if there is no change in the regular arrangement pattern of the plurality of conductive particles in the conductive particle group, there is a problem that it is time-consuming to create the regular arrangement pattern of the conductive particles constituting the conductive particle group in the transfer mold. In addition, in the case of the filler array film that can function as the anisotropic conductive film of Patent Document 2, although a transfer mold is not required, it is necessary to prepare an expensive laser lift-off device to carry out the laser lift-off method, and since roll-to-roll processing is not possible, the tact time may increase. In addition, when it is made of a curable resin, there are concerns about unintended hardening due to the radiant heat of the laser, distortion of the edge shape of the individual pieces, and chipping of the individual piece edges.

[0007] The present invention aims to solve the problems of the prior art, and aims to provide a structure that can be formed using a simple transfer mold without the need for a singulation process, such as the laser lift-off method, for the filler array film required for the creation of an image display device in which a large number of fine optical elements, such as a μLED display, are arranged on a display substrate, using a filler array film that can function as an anisotropic conductive film. The problems, configurations, and effects of the present invention will be described using μLEDs as an example, but the present invention can achieve the same effects even if the optical element is determined to be larger than μLEDs (mini LEDs). It can also be applied to micro-components other than optical elements. [Means for solving the problem]

[0008] The inventors have discovered that the object of the present invention can be achieved by providing a recess and a protrusion on one side of the insulating resin layer for retaining a filler of a filler-arranged film having an insulating resin layer for retaining a filler and a filler, and arranging a filler group consisting of a plurality of fillers on the protrusions, and have thus completed the present invention.

[0009] That is, the present invention is a filler-arranged film having a filler-retaining insulating resin layer and a filler, A recess and a protrusion are formed on one side of the filler-holding insulating resin layer, The present invention provides a filler-arranged film in which at least one filler group consisting of a plurality of fillers is arranged on the convex portion. Each filler constituting the filler group is preferably arranged on the top surface of the convex portion or in a state where at least a part of the filler is embedded in the filler-retaining insulating resin layer constituting the convex portion. In this filler-arranged film, the convex portions are preferably regularly arranged, and a plurality of fillers are preferably regularly arranged in the filler group. It is also preferable that no filler is arranged in the concave portion. Such a concave portion may penetrate the filler-retaining insulating resin layer. Another insulating resin layer may be laminated on at least one side of the filler-retaining insulating resin layer, and in that case, the convex portion may be separated from the other convex portions by the penetrating concave portion. Furthermore, another insulating resin layer may be laminated. As the other insulating resin layer laminated in this way, an insulating resin layer for forming a black matrix can be preferably adopted.

[0010] The present invention also relates to a method for producing the filler array film of the present invention, comprising the steps of: (Process A) A step of forming an insulating resin layer for retaining a filler on a release film that has been subjected to a release treatment; (Process B) A step of forming a recess and a protrusion on one side of the insulating resin layer for retaining the filler by contacting a pressing mold having a recess corresponding to the protrusion of the filler arrangement film with the insulating resin layer for retaining the filler and performing a heat press; and (Process C) a step of placing a filler-arranged surface of a filler transfer sheet, which has a plurality of fillers arranged on one side of a transfer substrate, facing the top surfaces of the protrusions and pressing the filler from the transfer substrate side, thereby transferring the filler to the top surfaces of the protrusions; The present invention provides a method for producing a filler-arranged film having the above structure.

[0011] In the method for producing the filler array film, the step C is followed by the following step D: (Process D) a step of embedding each of the fillers transferred onto the top surfaces of the protrusions in an insulating resin layer for holding the fillers so that at least a portion of each of the fillers is embedded; It is preferred that the compound has the formula:

[0012] Furthermore, the present invention provides a connection structure in which a second article is connected to a first article via the filler array film of the present invention, A connection structure is provided in which the second article corresponds (preferably one-to-one) to the convex portions of the filler array film. In this case, it is preferable that the first article is a transparent display substrate having a transparent electrode arranged on one side, the second article is a μLED having an electrode formed on one side, the filler arranged on the convex portions of the filler array film is a conductive particle, and the filler array film itself functions as an anisotropic conductive film.

[0013] The present invention also provides a method for producing a connection structure, characterized in that the above-mentioned filler-arranged film of the present invention is sandwiched between a first article and a second article, preferably so that the second article and the convex portion of the filler-arranged film correspond (preferably one-to-one), and pressure-bonded, for example, by thermocompression. In this case, it is preferable that the first article is a transparent display substrate having a transparent electrode arranged on one side, the second article is a μLED having an electrode formed on one side, the filler arranged on the convex portion of the filler-arranged film is a conductive particle, and the filler-arranged film itself functions as a conductive film or an anisotropic conductive film. Note that the filler-arranged film may be described using an anisotropic conductive film as an example, but the contents of the description can also be applied to the case where a conductive film is used as an example. In addition, as the second article to be the target, another minute light-emitting element such as a mini LED or a minute component (electronic component) can be applied instead of the μLED. An example of the size of the second article is one having a maximum length of one side of 200 μm or less. It may be a size of 10 to 30 μm square, which is extremely difficult to perform manual work. Effect of the Invention

[0014] The filler-arranged film of the present invention has an insulating resin layer for holding a filler and a filler, and has a plurality of recesses and protrusions on one side of the insulating resin layer for holding a filler. At least one filler group consisting of a plurality of fillers is arranged on each protrusion. The protrusions can be made to basically correspond one-to-one with the microelectronic components such as μLEDs to be connected with the filler-arranged film. Moreover, from a filler transfer sheet in which the fillers are regularly arranged all over the surface, the filler can be transferred only to the top surface of the protrusions, while the filler can be arranged not on the bottom of the recesses. Therefore, when a microelectronic component such as a fine-pitch μLED is anisotropically conductively connected to a wiring board or the like, the protrusions of the filler-arranged film can be made to function substantially as individual pieces of the filler-arranged film to achieve anisotropic conductive connection without worrying about short circuits. In addition, since a thin insulating resin layer can be left on the recesses, there is also the advantage that the protrusions are less likely to fall off during handling.

[0015] In addition, in the manufacturing method of the filler array film of the present invention, a press mold having a recess corresponding to the protrusion of the filler array film is brought into contact with the insulating resin layer for holding the filler and hot pressed to form a plurality of protrusions and recesses on one side of the insulating resin layer for holding the filler. Therefore, the planar shape and surface area of ​​the top surface of the protrusions of the filler array film, and the cross-sectional shape and height of the protrusions can be relatively easily formed by the press mold. Moreover, since there is no need to make fine holes in the press mold for regularly arranging the minute fillers, it is possible to create the press mold at low cost. In addition, in the manufacturing method of the filler array film of the present invention, the filler can be transferred only to the protrusions formed by the press mold using a conventional filler transfer sheet in which the filler is arranged over the entire surface. In other words, even if the arrangement of the filler group of the filler array film is changed, it is only necessary to create a new press mold that can be made relatively easily and at low cost. [Brief description of the drawings]

[0016] [Figure 1A] FIG. 1A is a schematic cross-sectional view of a filler array film of the present invention. [Figure 1B] FIG. 1B is a schematic cross-sectional view of the filler array film of the present invention. [Figure 1C] FIG. 1C is a schematic cross-sectional view of the filler array film of the present invention. [Figure 1D] FIG. 1D is a schematic cross-sectional view of the filler array film of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of a filler array film of the present invention. [Diagram 3] FIG. 3 is a schematic cross-sectional view of a filler array film of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view of a filler array film of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view of a filler array film of the present invention. [Figure 6]FIG. 6 is an explanatory diagram of a filler group on the top surface of a convex portion of a filler arranged film of the present invention. [Figure 7] FIG. 7 is an explanatory diagram of a filler group on the top surface of a convex portion of a filler arranged film of the present invention. [Figure 8] FIG. 8 is a schematic cross-sectional view of another embodiment of the filler array film of the present invention. [Figure 9A] FIG. 9A is a schematic cross-sectional view of another embodiment of the filler array film of the present invention. [Figure 9B] FIG. 9B is a schematic cross-sectional view of another embodiment of the filler array film of the present invention. [Figure 9C] FIG. 9C is a schematic cross-sectional view of another embodiment of the filler array film of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view of another embodiment of the filler arrangement film of the present invention. [Figure 11] FIG. 11 is a process explanatory diagram of the method for producing a filler arranged film of the present invention. [Figure 12] FIG. 12 is a process explanatory diagram of the method for producing the filler arranged film of the present invention. [Figure 13] FIG. 13 is a process explanatory diagram of the method for producing the filler arranged film of the present invention. [Figure 14] FIG. 14 is a process explanatory diagram of the method for producing the filler arranged film of the present invention. [Figure 15] FIG. 15 is a process explanatory diagram of the method for producing the filler arranged film of the present invention. [Figure 16] FIG. 16 is a process explanatory diagram of the method for producing the filler arranged film of the present invention. [Figure 17A] FIG. 17A is a schematic cross-sectional view of a filler arranged film obtained by steps A to C of the filler arranged film manufacturing method of the present invention. [Figure 17B] FIG. 17B is a schematic cross-sectional view of the filler arranged film obtained by steps A to D of the filler arranged film manufacturing method of the present invention. [Figure 18] FIG. 18 is an optical microscope photograph of the convex portion side surface of the filler arranged film of the present invention. [Figure 19] FIG. 19 is a partially enlarged photograph of the anisotropic conductive film produced using the stamping die 1. [Figure 20] FIG. 20 is a partially enlarged photograph of the anisotropic conductive film produced using the stamping die 2. [Figure 21] FIG. 21 is a diagram showing the wiring pattern of the glass substrate of the connection structure for evaluation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] <Filler array film> As shown in FIG. 1A, the filler array film 10 of the present invention has a filler retaining insulating resin layer 1 and a filler 2. On one side of the filler retaining insulating resin layer 1, a recess 3 and a protrusion 4 are preferably formed in multiple numbers. The protrusion 4 is a portion for retaining the filler 2, and at least one filler group 20 consisting of multiple fillers 2 is arranged on the protrusion 4. In FIG. 1A, the filler 2 constituting the filler group 20 is arranged on the surface of the protrusion 4, but as shown in FIGS. 1B to 1D, each filler 2 constituting the filler group 20 may be arranged so that at least a part of it is embedded in the filler retaining insulating resin layer 1 constituting the protrusion 4. For example, in FIG. 1B, almost half of the filler 2 is embedded in the filler retaining insulating resin layer 1, in FIG. 1C, the end of the filler 2 is embedded so as to be flush with the filler retaining insulating resin layer 1, and in FIG. 1D, the filler 2 is completely embedded without being exposed in the filler retaining insulating resin layer 1. When the filler is arranged on the convex parts of the filler-arranged film 10 of the present invention, the filler is not transferred to the inner bottom surface of the concave parts (non-convex parts). This is because the filler accommodated in the opening of the transfer mold (Patent No. 6187665) used to arrange the filler on the convex parts, or the filler arranged on the filler arrangement surface of the filler transfer sheet in FIG. 16 described later, does not reach (or is difficult to reach) the bottom of the concave parts of the filler-arranged film when the filler is transferred. Another factor is that the resin thickness at the bottom of the concave parts of the filler-arranged film is much thinner than the resin thickness of the convex parts, so that the adhesive strength of the concave parts is greatly reduced, making it difficult to transfer the filler. Therefore, each convex part functions substantially as a piece-like filler-arranged film. Therefore, when the filler is a conductive particle, the filler-arranged film can function substantially as a piece-like anisotropic conductive film.

[0019] The "arrangement" in the filler arrangement film has two meanings. One meaning is that the protrusions 4 themselves rising from the recesses 3 are arranged randomly or regularly (e.g., a square lattice arrangement, a hexagonal lattice arrangement, etc., but not limited to a lattice arrangement), as shown in Fig. 1, and the other meaning is that the filler 2 itself in the filler group 20 arranged in the protrusions 4 is arranged randomly or regularly (e.g., a square lattice arrangement, a hexagonal lattice arrangement, etc.). From the viewpoints of filler capture ability and production costs, it is preferable that the arrangement of the protrusions 4 and the arrangement of the filler 2 are each regularly arranged (particularly a hexagonal lattice arrangement).

[0020] (Insulating resin layer 1 for holding filler) The filler-retaining insulating resin layer 1 constituting the filler array film 10 of the present invention can have the same configuration as the insulating resin layer that retains the filler in the conventional anisotropic conductive film or conductive film, and can be formed, for example, from a thermosetting resin composition. Such a thermosetting resin composition preferably contains a rubber component, a film-forming resin, a thermosetting resin, a thermosetting agent, and an inorganic filler. This inorganic filler is different from the filler arranged in the convex portion 4, and is uniformly dispersed in the filler-retaining insulating resin layer 1. The filler-retaining insulating resin layer 1 can contain other known additives as necessary within a range that does not impair the effects of the invention. The layer thickness of the filler-retaining insulating resin layer 1 can be appropriately determined depending on the shape and surface area of ​​the concave portion 3 and the convex portion 4, but is preferably equal to or greater than the average particle diameter of the filler and not greater than two times. If the layer thickness is too thick, there is a concern that the bottom thickness of the concave portion 3 will not be thin, and the filler may be arranged, or the light transmittance of the concave portion 3 may be reduced. In addition, when articles are joined together using the filler-arranged film, there is a concern that the separated protrusions 4 may stick together. Conversely, if the film is too thin, there is a concern that the amount of resin in the protrusions 4 may be insufficient, making it impossible to form the intended shape. An example of the filler-retaining insulating resin layer 1 is one that functions as an adhesive film or connection film having adhesiveness, such as a general anisotropic conductive film.

[0021] *Rubber component The rubber component contained in the thermosetting resin composition is a component for imparting cushioning properties (shock absorption properties) to the filler-retaining insulating resin layer, and is not particularly limited as long as it is an elastomer with good cushioning properties. Specific examples include, for example, acrylic rubber, silicone rubber, butadiene rubber, and polyurethane resin (polyurethane-based elastomer). Among these, it is preferable to use one or more types selected from acrylic rubber and silicone rubber. The content of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, relative to 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler.

[0022] *Film forming resin Examples of the film-forming resin include various resins such as phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, acrylic resin, polyimide resin, butyral resin, etc., preferably having a weight average molecular weight of about 10,000 to 80,000 from the viewpoint of film-forming properties, and these may be used alone or in combination of two or more. Among these, it is preferable to use phenoxy resin from the viewpoint of film formation state, connection reliability, etc. The content of the film-forming resin is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 35 parts by mass or more, preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler.

[0023] *Thermosetting resin Examples of the thermosetting resin include epoxy compounds and (meth)acrylate compounds, and epoxy compounds are particularly preferred. These compounds may be monomers, oligomers, or polymers. The content of the thermosetting resin is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less, based on 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler.

[0024] The epoxy compound that can be used as the thermosetting resin is not particularly limited as long as it is an epoxy compound having one or more epoxy groups in the molecule, and may be, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a urethane-modified epoxy resin. Among these, a high-purity bisphenol A type epoxy resin can be preferably used. A specific example of a high-purity bisphenol A type epoxy resin is the product name "YL980" manufactured by Mitsubishi Chemical Corporation. When an epoxy compound is used as the thermosetting resin, the content of the epoxy compound is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 45 parts by mass or less, relative to 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler.

[0025] *Heat curing agent The thermosetting agent is selected according to the thermosetting resin. For example, when the thermosetting resin is an epoxy compound, a thermal anionic polymerization initiator or a thermal cationic polymerization initiator can be preferably selected, and a thermal cationic polymerization initiator that can suppress the curing reaction caused by laser light and rapidly cure by heat can be more preferably selected. The content of the thermosetting agent can be determined according to the type of the thermosetting agent and the type of the thermosetting resin. The content of the thermosetting agent is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less, based on 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler.

[0026] In addition, the thermal cationic polymerization initiator preferably applicable to the epoxy compound is one that generates an acid capable of cationic polymerization of a cationic polymerization type compound by heat, and known iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, etc. can be used. Among these, aromatic sulfonium salts that show good latency against temperature can be preferably used. A specific example of an aromatic sulfonium salt-based polymerization initiator is, for example, San-Aid SI-60L, a product name manufactured by Sanshin Chemical Industry Co., Ltd. The content of such a thermal cationic polymerization initiator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less, relative to 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler.

[0027] *Inorganic filler The inorganic filler in the thermosetting resin composition is used for the purpose of adjusting the durometer A hardness, storage modulus at a frequency of 200 Hz, and storage modulus after curing of the filler-retaining insulating resin layer 1, and may be silica, talc, titanium oxide, calcium carbonate, magnesium oxide, silane coupling agents, fillers, softeners, colorants, flame retardants, thixotropic agents, etc. The inorganic fillers may be used alone or in combination of two or more kinds.

[0028] The content of the inorganic filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less, based on 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler. In particular, when the content of the rubber component is 2 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler, by setting the content of the inorganic filler to 8 parts by mass or more and 12 parts by mass or less, it is possible to easily achieve the desired durometer A hardness, storage modulus at a frequency of 200 Hz, and storage modulus after curing.

[0029] (Protruding part 4) The protrusion 4 holds the filler 2, and preferably holds the filler 2 on its top surface or on the filler-holding insulating resin layer 1 constituting the protrusion 4. When a second article such as a μLED is bonded to a first article such as a wiring board, the protrusion 4 is preferably formed at a position corresponding to the second article. In this case, the second article and the protrusion 4 preferably correspond to each other in a 1:1 ratio, but one protrusion 4 may correspond to two or more second articles.

[0030] It is preferable that the planar shape and size (area) of the protrusion 4 are approximately the same as the planar shape and size of the second article to be joined or its electrode. For example, when the second article is a μLED, it is preferable that the planar shape and size of the protrusion 4 are approximately the same as the outer shape of the μLED or one electrode in the μLED. For example, one side may be 5 μm or more and 100 μm or less, and it is preferable that the protrusion 4 is a rectangle with one side being 10 μm or more and 30 μm or less. In addition, in Figures 1A to 1D, the side of the protrusion 4 rises vertically from the recess 3, but it may have a taper as shown in Figure 2, or may be stepped as shown in Figure 3. Note that the planar shape and size (area) of the protrusion 4 have been described using a μLED as an example of the second article to be connected, but a relatively large article such as a mini LED can also be used as the connection object. The size of the protrusion 4 may be adjusted according to the size of the connection object. Even if a part has an outer shape of 100 μm or more on one side, it can be used as the connection object as long as it does not impair the effects of the invention.

[0031] The height t0 of the protrusion 4 (see FIG. 1A) corresponds to the thickness of the insulating resin layer 1 for retaining the filler. Considering the difficulty of arranging the filler and the strength when the second article is joined, the height is usually 1 μm or more, preferably 2 μm or more, preferably 20 μm or less, more preferably 10 μm or less, and is preferably 1 to 2 times the average particle diameter of the filler 2. By making the height of the protrusion 4 larger than the bump height of the component to be connected and smaller than the sum of the thickness of the component to be connected and the bump height, the component to be connected is not completely buried in the insulating resin layer 1 for retaining the filler, and a fillet can be formed on the periphery of the component. It is preferable that the planar shape, size (area), height, and relationship between the convex surface and the bottom surface of the protrusion 4 are all uniform, but this is not limited thereto.

[0032] Number density of protrusions 4 [pieces / mm 2 The optimum density can be selected according to the purpose of use of the filler array film and the objects to be joined. Generally, it is 50 [pieces / mm 2 ] or more 10000[pcs / mm 2] or less, but when the filler array film is used as an anisotropic conductive film or conductive film and applied to the mounting of μLEDs, it is preferably 100 [pieces / mm 2 ] or more, more preferably 300 [pieces / mm 2 ] or more, preferably 3000 [pieces / mm 2 ] or less, more preferably 1500 [pieces / mm 2 In addition, the minimum distance between the protrusions 4 is preferably 5 μm or more in order to avoid adhesion between separated pieces during the particle transfer process and component mounting.

[0033] The number of fillers provided on one protrusion 4 is not particularly limited, but the lower limit is preferably 2 or more and the upper limit is preferably 1500 or less. Considering that the fillers are captured by a maximum of two electrodes provided on a component with a very small external shape, it is preferable to set the number in this range.

[0034] (Recess 3) The recess 3 is formed reflectively when the protrusion 4 is formed, and has the function of separating the protrusion 4 from the adjacent protrusion 4. There is no particular limit to the depth t1 and width w1 of the recess 3, and they can be appropriately determined in consideration of the shape and size of the second article to be bonded with the filler-arranged film. In Figs. 1A to 1D, the inner wall of the recess 3 is vertical and the bottom is flat, but this is not limited thereto. As shown in Fig. 4, the recess 3 may have a tapered shape that widens upward, or as shown in Fig. 5, the recess 3 may have a stepped shape. In the case of Figs. 4 and 5, the side surface of the protrusion 4 may be as shown in Fig. 2 or 3.

[0035] Furthermore, by reducing the thickness of the bottom of the recess 3, the light transmittance of that part is improved, making it easier to optically distinguish it from the protrusion 4, and making it easier to handle the protrusion 4 as a substantially individual piece of the filler array film 10. Note that at least a part of the bottom of the recess 3 may be perforated as long as the protrusion 4 is not completely cut off from the filler array film 10. This is because the protrusion 4 that is completely cut into an individual piece by perforating the recess 3 cannot be handled as a part of the filler array film 10.

[0036] (Filler 2) As the filler 2 arranged in the convex portion 4, various fillers used in known filler-arranged films can be appropriately selected and used depending on the application of the filler-arranged film (conductive film, anisotropic conductive film, adhesive film, optical film, ferromagnetic film, etc.). For example, from known inorganic fillers (metals, metal oxides, metal nitrides, etc.), organic fillers (resin particles, rubber particles, etc.), and fillers in which organic and inorganic materials are mixed (for example, particles whose cores are formed of a resin material and whose surfaces are metal-plated (metal-coated resin particles), conductive particles with insulating fine particles attached to their surfaces, conductive particles with their surfaces insulated, etc.), the filler 2 can be appropriately selected depending on the performance required for the application, such as hardness and optical performance. For example, in optical films and matte films, silica fillers, titanium oxide fillers, styrene fillers, acrylic fillers, melamine fillers, various titanates, etc. can be used. In the film for capacitors, titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, calcium titanate, strontium titanate, barium titanate, barium titanate zirconate, lead titanate zirconate, and mixtures thereof can be used. In the adhesive film, polymer-based rubber particles, silicone rubber particles, and the like can be contained. In the anisotropic conductive film, conductive particles are contained. Examples of conductive particles include metal particles such as nickel, cobalt, silver, copper, gold, and palladium, alloy particles such as solder, metal-coated resin particles, and metal-coated resin particles with insulating fine particles attached to the surface. Two or more types can be used in combination. Among them, metal-coated resin particles are preferred because the resin particles repel each other after connection, making it easier to maintain contact with the terminal, and the conductive performance is stable. In addition, the surface of the conductive particles may be subjected to an insulating treatment by a known technique that does not interfere with the conductive characteristics. The fillers listed above by application are not limited to the applications, and may be contained in the filler arrangement film for other applications as necessary. In addition, in the filler-arranged film for each application, two or more kinds of fillers can be used in combination as necessary.

[0037] The shape of the filler 2 is appropriately selected from a sphere, an elliptical sphere, a columnar shape, a needle shape, a combination thereof, etc., depending on the application of the filler-arranged film. A sphere is preferable because it is easy to check the filler arrangement and to maintain a uniform state. In particular, in an anisotropic conductive film, it is preferable that the conductive particles are approximately spherical. By using approximately spherical conductive particles, when manufacturing an anisotropic conductive film in which conductive particles are arranged using a transfer mold as described in JP-A-2014-60150, for example, the conductive particles roll smoothly on the transfer mold, so that the conductive particles can be filled into a predetermined position on the transfer mold with high precision. Therefore, the conductive particles can be accurately arranged.

[0038] Here, substantially spherical means that the sphericity calculated by the following formula is 70 to 100.

[0039]

number

[0040] In the above formula, So is the area of ​​the circumscribing circle of the filler in the planar image of the filler, and Si is the area of ​​the inscribing circle of the filler in the planar image of the filler.

[0041] In this calculation method, it is preferable to take planar images of the filler in the surface view and cross section of the filler array film, measure the area of ​​the circumscribed circle and the area of ​​the inscribed circle of any 100 or more fillers (preferably 200 or more fillers) in each planar image, and obtain the average value of the circumscribed circle area and the average value of the inscribed circle area, and set them as the above-mentioned So and Si. It is also preferable that the sphericity is within the above range in both the surface view and the cross section. The difference in sphericity between the surface view and the cross section is preferably within 20, more preferably within 10. Since the inspection during the production of the filler array film is mainly in the surface view, and the detailed pass / fail judgment after thermocompression bonding to the article is performed in both the surface view and the cross section, it is preferable that the difference in sphericity is small. Note that this sphericity can also be obtained using a wet flow type particle size and shape analyzer FPIA-3000 (Malvern Instruments) if it is a single filler.

[0042] The particle diameter D of the filler is appropriately determined depending on the application of the filler-arranged film. For example, in an anisotropic conductive film, in order to accommodate variations in wiring height, suppress an increase in conductive resistance, and suppress the occurrence of short circuits, the particle diameter D is preferably 1 μm or more, more preferably 2.5 μm or more, preferably 30 μm or less, and more preferably 9 μm or less. Depending on the object to be connected, a particle diameter larger than 9 μm may be suitable.

[0043] The particle diameter D of the filler before being arranged on the convex portion 4 of the filler array film 10 can be measured by a general particle size distribution measuring device, and the average particle diameter can also be obtained by using a particle size distribution measuring device. An example of a particle size distribution measuring device is FPIA-3000 (Malvern Instruments). On the other hand, the particle diameter D of the filler in the filler array film can be obtained by observation with an electron microscope such as SEM. In this case, it is preferable to set the number of samples for measuring the particle diameter D to 200 or more. In addition, when the shape of the filler is not spherical, the maximum length or the diameter of a shape simulating a sphere can be taken as the particle diameter D of the filler.

[0044] In the present invention, the variation in the particle diameter D of the filler in the filler-arranged film is set to 20% or less as a CV value (standard deviation / average). By setting the CV value to 20% or less, the filler-arranged film is easily pressed evenly when it is pressed onto an article, and especially when the filler is arranged, it is possible to prevent the pressing force from concentrating locally, which contributes to the stability of the connection. In addition, the connection state can be accurately evaluated by indentation after connection. Specifically, when the filler-arranged film is configured as an anisotropic conductive film, in an inspection after anisotropic conductive connection between the anisotropic conductive film and an electronic component, the connection state can be accurately confirmed by indentation whether the terminal size is large (FOG, etc.) or small (COG, etc.). Therefore, it is expected that the inspection after anisotropic conductive connection will be facilitated, and the productivity of the connection process will be improved.

[0045] Here, the variation in particle size can be calculated by an image type particle size analyzer or the like. The particle size of the filler as the raw material particle of the filler array film that is not contained in the filler array film can also be determined by using the above-mentioned wet flow type particle size and shape analyzer FPIA-3000 (Malvern Instruments). In this case, if the number of fillers is measured at 1000 or more, preferably 3000 or more, and more preferably 5000 or more, the variation in the particle size of the single filler can be accurately grasped. When the filler is arranged in the filler array film, it can be determined from a planar image or a cross-sectional image in the same manner as the above-mentioned sphericity.

[0046] (Filler group 20) The filler group 20 is composed of a plurality of fillers arranged on the convex portion 4 in order to enhance the capture of the filler when the second article is bonded to the first article via the filler array film 10. In the present invention, as described above, at least one filler group 20 consisting of a plurality of fillers 2 is arranged on the convex portion 4. Therefore, a plurality of filler groups 20 may be arranged on one convex portion. In that case, as shown in FIG. 6 (a plan view of one convex portion), it is preferable that the adjacent filler groups (20a and 20b) on one convex portion 4 are completely separated from each other, but as shown in FIG. 7, they may be separated so that some of the fillers 2a are common. In particular, when the filler groups are completely separated as shown in FIG. 6, for example, when connecting a μLED with a filler array film, the separated filler groups 20a and 20b can be made to correspond to the anode electrode and cathode electrode of the μLED, respectively, to prevent a short circuit from occurring between them. As already mentioned, the fillers 2 in the filler group 20 may be arranged randomly, but it is preferable that they are arranged regularly (for example, a square lattice arrangement, a hexagonal lattice arrangement, etc., but not limited to a lattice arrangement) from the viewpoint of filler capture and manufacturing costs. The filler group provided in one protrusion 4 also includes an embodiment in which a plurality of filler groups are present at a distance from each other. This is because when the filler group 20 is arranged in the protrusion 4, it may be designed in advance to be a plurality of filler groups in accordance with the object (for example, arranged only on the electrode). One of the preferable features of the present invention is that the outer periphery or outer edge of the filler group and the outer shape of at least the top surface of the protrusion 4 are the same.

[0047] In the present invention, the convex portions are isolated and spaced apart, and a plurality of fillers are disposed on each convex portion. Although disposing one filler on one convex portion is effective for fixing each filler, from the viewpoint of practical use, it is necessary to densely dispose a plurality of such convex portions, so it is necessary to increase the thrust force to push the filler into the resin, and this tendency is further increased when the resin holding the filler has a high viscosity. Therefore, a low-viscosity resin design is required, but if the viscosity is low, it becomes difficult to release the filler from the transfer mold in a balanced manner, and the resin design becomes difficult. On the other hand, in the case of the present invention in which a plurality of fillers are disposed on one convex portion, the amount of resin is relatively small relative to the amount of filler compared to the case in which one filler is disposed on one convex portion, so excessive thrust force is not particularly required when pushing. In other words, there is an advantage in that the conditions such as resin flow and resin filling can be adjusted depending on the design conditions of the convex portion, and the fact that the degree of freedom in resin design is increased can be said to be a major feature of the present invention. For example, by designing one or two protrusions to span between two electrodes, the size of the protrusions and the area of ​​the filler provided on the protrusions can be adjusted to suit design conditions such as the area of ​​the electrodes and the distance between the electrodes, stabilizing the connection conditions and greatly contributing to productivity. For example, if the dimensions of the entire μLED element are 30×60 μm and the dimensions of one electrode are 20×20 μm (area: 400 μm), 2 ), and assuming that two electrodes are connected with two protrusions, the specifications of the protrusions are not particularly limited as long as the electrodes hold fillers, but the dimensions of the protrusions are preferably 20×20 μm or more, and it is preferable that there are three or more fillers on one protrusion. When two electrodes are connected with one protrusion, the dimensions of the protrusions are preferably 30×60 μm or more, and it is preferable that there are ten or more fillers. In connecting minute components, this reduces the constraints on the pressing device, such as thrust force, and can be said to be a remarkable effect of the present invention.

[0048] The number density of the fillers in the filler group 20 is not particularly limited and is appropriately determined depending on the purpose of use of the filler array film, the external size of the connection target, the electrode layout, and the degree of fine pitch.2 ] (which may be considered as the area obtained by connecting only the convex portions), the lower limit is preferably 100 or more, more preferably 1000 or more, and even more preferably 10,000 or more, and the upper limit is preferably 300,000 or less, more preferably 200,000 or less, and even more preferably 100,000 or less.

[0049] <Deformation of the filler-arranged film> In the filler array film of the present invention, another insulating resin layer can be laminated on at least one side of the insulating resin layer for retaining fillers. For example, as shown in FIG. 8, another insulating resin layer 5 may be provided on the convex portion 4 side of the insulating resin layer for retaining fillers 1, and as shown in FIG. 9A, another insulating resin layer 6 may be provided on the opposite side of the convex portion 4. In this case, as shown in FIG. 9B, the concave portion 3 may be penetrated to the insulating resin layer 6, and as shown in FIG. 9C, the concave portion 4 may be separated from the other convex portions by the penetrating concave portion 3 and made independent. In the case of FIG. 9B, even if the insulating resin layer 6 is not provided, since there is a concave portion 3 that does not penetrate, the penetrating concave portion 3 can be maintained as it is. In addition, as shown in FIG. 10, insulating resin layers 5 and 6 may be provided on both sides. The other insulating resin layers 5 and 6 may be considered to be substantially the same as those described in the insulating resin layer for retaining fillers 1.

[0050] Such another insulating resin layer 5 and insulating resin layer 6 can be formed from the same composition as the filler-retaining insulating resin layer 1. The composition may be changed or adjusted according to the purpose. The total resin thickness of the filler-arranged film including these layers is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, and preferably 30 μm or less, more preferably 15 μm or less, and even more preferably 8 μm or less.

[0051] In addition, if the other insulating resin layers 5 and 6 contain a black pigment, they can function as insulating resin layers for forming a black matrix. For example, as shown in Fig. 11, when the filler array film 10 of Fig. 8 is sandwiched between the wiring board 100 as the first article and the μLED 200 as the second article and thermocompressed with a heat tool H, as shown in Fig. 12, a fillet F is formed from the insulating resin layer for forming a black matrix on the side of the μLED 200, and this fillet F can function as a black matrix.

[0052] Known black pigments such as carbon black and titanium black can be used as the black pigment. Among them, titanium black, which has an extremely low content of impurity ions and is itself insulating, can be preferably used. When titanium black is used as the black pigment, the content of titanium black in the black resin composition for black matrix is ​​preferably 5% by mass or more, more preferably 10% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less. The average particle size of these black pigments is 10 to 100 nm. It is desirable that this black pigment is smaller than the average particle size of the conductive particles.

[0053] <Manufacturing method of filler array film> The filler arranged film of the present invention can be produced by a production method including the following steps A to C. This production method preferably includes a step D following the step C.

[0054] (Process A) Step A is a step of forming a filler-retaining insulating resin layer 1 on a release film (PET) 30 that has been subjected to a release treatment, as shown in Fig. 13. The filler-retaining insulating resin layer can be formed by a conventional method, for example, by applying a filler-retaining insulating resin composition to a release film to form a film.

[0055] (Process B) In step B, as shown in FIG. 14, a press mold 8 having a recess 7 corresponding to the protrusion of the filler-arranged film is brought into contact with the filler-retaining insulating resin layer 1 obtained in step A and heat-pressed to form a recess 3 and a protrusion 4 on one side of the filler-retaining insulating resin layer (see FIG. 15). A release film may be interposed during the contact. As the press mold 8, a single metal or resin plate having a recess is preferable, but a roll having a recess may also be used. A film having a recess may also be used. As a method of heat pressing, a general heat tool, a vacuum laminator, etc. may be used. In addition, the shape, depth, pitch, etc. of the recess 7 can be appropriately determined according to the shape, height, and pitch of the protrusion of the filler-arranged film (in other words, the shape, thickness, pitch, surface area, etc. of the second article to be connected). For example, if a μLED is selected as the second item, the depth of the recess is preferably 1 μm or more, more preferably 2 μm or more, and more preferably 20 μm or less, and more preferably 10 μm or less, since if the recess is too shallow it becomes difficult to arrange the filler, and if it is too deep there is a concern that the μLED will be buried in the resin.

[0056] (Process C) In step C, as shown in FIG. 16, the filler arrangement surface of the filler transfer sheet 41, on which a plurality of fillers 2 are arranged on one side of the transfer substrate 40, is placed against the top surface of the convex portion 4 of the filler-holding insulating resin layer 1, and pressed from the transfer substrate 40 side, thereby transferring a plurality of fillers 2 to the top surface of the convex portion 4. After the transfer, the filler transfer sheet 41 is peeled off and removed to obtain a filler array film 10 laminated on the release film 30, as shown in FIG. 17A. FIG. 18 shows an example of an optical microscope photograph of the filler array film 10 taken from the convex portion side. It can be seen that the filler 2 is arranged in a hexagonal lattice pattern on the surface of the convex portion 4, and no filler is present in the concave portion 3. In FIG. 16, the filler 2 is held on the surface of the adhesive transfer substrate 40 of the filler transfer sheet 41, but a transfer mold having a concave portion for accommodating the filler may be used as the transfer substrate 40.

[0057] (Process D) In the method for producing the filler array film of the present invention, following step C, it is preferable to embed the filler 2 transferred to the top surface of the protrusion 4 in the filler-retaining insulating resin layer 1 by a known heat pressing method such as heat pressing via a release film (PET). This results in a filler array film 10 as shown in Fig. 17B. A detailed description of lamination of another insulating resin layer will be omitted, but a laminated one may be prepared in advance, or may be laminated after step D.

[0058] As described above, one of the features of the manufacturing method of the filler-arranged film is the use of a press mold in step B. By using such a press mold, it is possible to obtain a filler-arranged film that can function as an individual piece in which fillers are arranged only in the convex parts formed at the intended positions of the filler-arranged film. Moreover, at least one filler can be arranged in the convex parts of the filler-arranged film, and the convex parts and the concave parts can be arranged in the intended positions relative to the entire film. In addition, since the film thickness of the concave parts is thin, the film has excellent light transmittance and visibility. In addition, the presence of the concave parts where no filler is present can greatly reduce the risk of short circuiting when the filler-arranged film is used as an anisotropic conductive film. In addition, the filler-arranged film can be composed of a single resin film, and other resin layers can also be laminated thereon, which has the advantage of increasing the degree of freedom in design.

[0059] The filler transfer sheet 41 has the filler 2 arranged on one side of the transfer substrate 40, but since the filler is not transferred to the recesses 3 of the filler-retaining insulating resin layer 1, the filler can be arranged randomly or regularly, preferably in a hexagonal lattice pattern, all over the surface of the filler transfer sheet 41, making it easy to prepare the filler transfer sheet 41. The number density of the filler in the filler transfer sheet 41 is the same as the number density of the filler in the filler group of the filler array film.

[0060] <Connection structure and method for producing same> The filler array film of the present invention can be preferably applied to the filler array film of a connection structure in which a plurality of second articles are connected to a relatively large first article such as a wiring board via the filler array film, and can also be preferably applied to the filler array film in a method for manufacturing a connection structure characterized in that the filler array film is sandwiched between the first article and the second article, preferably so that the convex parts of the filler array film correspond to the convex parts of the second article, and then pressure-bonded (for example, thermocompression bonding). In these cases, the convex parts of the filler array film may correspond to the convex parts of the second article in a multiple-to-one or one-to-multiple correspondence, but from the viewpoints of ease of design and positional accuracy, it is preferable that they correspond one-to-one. In addition, it is preferable that the first article and the second article have electrodes so that they can be electrically connected to each other. It can also be used for conductive connection or anisotropic conductive connection by sandwiching the filler array film between the first article and the second article having opposing electrodes. In particular, the connection structure of the present invention can be preferably applied to the manufacture of a connection structure in which the first article is a transparent display substrate with a transparent electrode arranged on one side, the second article is a μLED with an electrode formed on one side, the filler arranged on the convex portion of the filler array film is a conductive particle, and the filler array film itself functions as a conductive film. Therefore, not only such a connection structure itself but also its manufacturing method itself is a modified embodiment of the present invention. Note that an anisotropic conductive film can also be used instead of the conductive film.

[0061] (μLED display as a connection structure) When manufacturing a μLED display using the filler array film of the present invention, in other words, when connecting the electrodes of the μLEDs and the electrodes of the substrate in a state where a plurality of μLEDs are regularly arranged on a wafer, first, the filler array film is aligned and attached to the electrodes of the substrate, and the filler array film and the μLEDs arranged on the wafer are aligned and attached to each other, and then heated and pressurized to connect the electrodes of the μLEDs and the electrodes of the substrate. In this case, the connection may be made by heating and pressing in a two-stage manner (JP Patent Publication 2019-216097). In addition, when the conductive particles are solder particles or the like, the connection may be made by reflow. Although the connection structure has been described using a μLED display as an example, the connection structure of the present invention can also be applied to displays using larger light-emitting elements.

[0062] The filler array film of the present invention is substantially in the form of individual pieces, but can also be used as a filler array film in which the convex portion is completely separated from the entire film. In that case, the temporary attachment of the individualized filler array film can be performed using a known method such as a method using a stamp material or a laser (laser lift-off method) or a method that applies the same (for example, the method described in JP-A-9-124020, JP-A-2011-76808, JP-A-6636017, JP-A-6187665, etc.), and is not particularly limited as long as the method can exhibit the effects of the invention. In the case of creating a filler transfer sheet and mounting a μLED on a substrate, a known method such as a method using a stamp material or a laser (laser lift-off method) or a method that applies the same can be used. EXAMPLES

[0063] The present invention will be described in detail below with reference to examples and comparative examples. In the examples and comparative examples, anisotropic conductive films, which are specific embodiments of a filler-arranged film, were prepared.

[0064] Reference Example 1 <Formation of insulating resin layer for retaining conductive particles in anisotropic conductive film> The composition (unit: parts by mass) with the formulation shown in Table 1 was mixed uniformly, and the resulting mixture was applied to a 50 μm thick polyethylene terephthalate film that had been treated for release, to the layer thickness shown in Table 1. It was then dried at 60°C for 3 minutes to obtain an adhesive film as an insulating resin layer for retaining conductive particles.

[0065] [Table 1]

[0066] Reference Example 2 <Molds used in Examples and Comparative Examples> Assuming that μLEDs will be mounted on a substrate using anisotropic conductive film, the following stainless steel press dies 1 and 2 were prepared as press dies for forming convex portions in the insulating resin layer for holding the conductive particles of the anisotropic conductive film. Press 1 is used when one concave portion corresponds to one μLED, and press dies 2 is used when two concave portions correspond to one μLED.

[0067] *Mold 1: Indentation size: 40 μm vertical × 60 μm horizontal × 4 μm deep, indentation pitch: 30 μm vertically and horizontally; Figure 19 shows a partially enlarged view of the anisotropic conductive film created using the stamping die 1. This figure shows that the conductive particles 2 are arranged only on the top surface of the protrusions 4. Also, the dotted line shows the outer shape of the μLED to be mounted, and indicates that there is a one-to-one correspondence between the protrusions 4 and the μLEDs.

[0068] *Mold 2: Depression size: 40 μm long x 20 μm wide x 4 μm deep, space between paired depressions: 20 μm, depression pitch: 30 μm long and 30 μm wide; Figure 20 shows a partially enlarged view of the anisotropic conductive film created using the stamping die 2. This figure shows that the conductive particles 2 are arranged only on the top surface of the protrusions 4. Also, the dotted line shows the outer shape of the μLED to be mounted, and indicates a two-to-one correspondence between the protrusions 4 and the μLEDs.

[0069] Reference Example 3 <Preparation of conductive particle transfer sheet> A conductive particle transfer sheet was created by applying conductive particles (Micropearl AU series, Sekisui Chemical Co., Ltd.) having the average particle size shown in Table 2 to the entire surface of the film so as to achieve the number density shown in Table 2, in accordance with the conductive particle regular array process described in paragraphs 0111-0112 and Figure 1A of Japanese Patent No. 6,187,665.

[0070] Examples 1-7, Comparative Examples 1-4 <Formation of anisotropic conductive film> The anisotropic conductive films used in the examples and comparative examples were prepared according to Table 2. That is, in the case of the examples, stamping mold 1 or stamping mold 2 was placed on the insulating resin layer for holding conductive particles prepared in Reference Example 1, and stamping was performed using a vacuum laminator, thereby forming convex portions and concave portions in the insulating resin layer for holding conductive particles corresponding to the concave portions and non-convex portions of the stamping mold. Next, the conductive particle arrangement surface of the conductive particle transfer sheet of Reference Example 3 was superimposed on the convex portion-forming surface of the insulating resin layer for holding conductive particles, and the conductive particles were transferred only to the convex portions by heating and pressing with a heat tool, thereby obtaining an anisotropic conductive film.

[0071] The conductive particle areal density in Example 1-7 is the areal density on the convex portions of the film, and the conductive particle areal density in Comparative Example 1-4 is the areal density over the entire surface of the film.

[0072] <Creating connection structures for evaluating electrical resistance and insulation> The Cr / Au layer of the glass substrate was patterned to match the convex pattern of the filler array film of the example, as shown in Figure 21. The anisotropic conductive films of the examples and comparative examples were aligned and attached to the obtained Cr / Au pattern of the glass substrate, a 1.5 cm square IC chip simulating a μLED was placed on it, and a connection structure for evaluating conductive resistance and insulation was obtained by thermocompression bonding under conditions of 150°C, 10 Pa, and 30 seconds.

[0073] <Creation of a connection structure for evaluating visible light transmittance> IC chips measuring 30 μm × 50 μm were prepared as μLEDs for measuring visible light transmittance. These IC chips were arranged in an area of ​​1.5 cm square and similarly thermocompressed to obtain a connection structure for evaluating visible light transmittance.

[0074] <Conductivity resistance evaluation> The conductive resistance of the connection structure for evaluating conductive resistance and insulation was measured by a conventional method and evaluated according to the following criteria. The evaluation results are shown in Table 2. For practical purposes, an A or B rating is desirable.

[0075] (Conductivity resistance evaluation criteria) Rank: Criteria A: 30Ω or less B: Over 30 Ω and under 100 Ω C: Over 100 Ω and under 300 Ω D: Over 300 Ω

[0076] <Insulation evaluation> Regarding the insulation of the connection structure for evaluating the conductive resistance and insulation, 100 points between electrodes spaced 5 μm apart were selected, and the resistance value of each was measured by the usual method. The number of points where short circuits occurred was counted and rated according to the following criteria. The evaluation results are shown in Table 2. For practical purposes, a rating of A, B, or C is desirable. 7 A resistance of Ω or less was judged as a short circuit.

[0077] (Insulation evaluation criteria) Rank: Criteria A: 0 short circuits (no short circuits) B: One short circuit C: Two short circuits D: Three or more short circuits

[0078] <Light transmittance evaluation> The average light transmittance of the connection structure for evaluating light transmittance to visible light of 400 to 700 nm was measured using a commercially available light transmittance measuring device and evaluated according to the following criteria. The evaluation results are shown in Table 2. In practical use, a rating of A, B, or C is desirable.

[0079] (Light transmittance evaluation criteria) Rank: Criteria A: Visible light transmittance is 50% or more B: Visible light transmittance is 35% or more and less than 50% C: Visible light transmittance is 20% or more and less than 35% D: Visible light transmittance is less than 20%

[0080] [Table 2]

[0081] The results in Table 2 show that the anisotropic conductive film of Example 1-7, in which conductive particles were arranged only on the convex portions created by a mold in the insulating resin layer for retaining conductive particles of the anisotropic conductive film, was able to allow the convex portions to function essentially as individual pieces of anisotropic conductive film, and showed results that were satisfactory for practical use in terms of conduction resistance, insulation, and visible light transmittance.

[0082] In the anisotropic conductive films of Comparative Examples 1 to 4, conductive particles were disposed over the entire surface of the film, which caused problems with visible light transmittance. [Industrial Applicability]

[0083] According to the filler array film of the present invention, when fine-pitch microelectronic components such as μLEDs are anisotropically conductively connected to a wiring board or the like, the convex portions of the filler array film can be made to function as individual pieces of the filler array film to achieve anisotropic conductive connection without worrying about short circuits, and the filler array film of the present invention has a structure that can be formed using a simple transfer mold. Therefore, the filler array film of the present invention has a structure comparable to that of individualization by the laser lift-off method, and is useful for manufacturing μLED displays.

[0084] Although the filler array film of the present invention has been described using an anisotropic conductive film and an anisotropic conductive connection method using the same as an example, the contents of the description can also be applied to the case where a conductive film and a conductive connection method using the same are used as an example, as long as the effects of the present invention are not impaired. [Explanation of symbols]

[0085] 1. Insulating resin layer for retaining filler 2. 2a Filler, conductive particles 3. Recess 4 Convex 5, 6 Another insulating resin layer 7. Die recess 8 Press Mold 10 Filler array film 20, 20a, 20b Filler group 30 Release film 40 Transfer substrate 41 Filler transfer sheet 100 Wiring board 200μLED H Heat Tool

Claims

1. A filler array film having an insulating resin layer for retaining fillers and fillers, A recess and a protrusion are formed on one side of the insulating resin layer for retaining the filler. A filler array film in which at least one filler group consisting of multiple fillers is arranged on the aforementioned protrusion.

2. The filler array film according to claim 1, wherein each filler constituting the filler group is arranged such that at least a portion of it is embedded on the top surface of the protrusion or in the insulating resin layer for holding the filler constituting the protrusion.

3. A filler arrangement film according to claim 1 or 2, wherein the protrusions are arranged in a regular pattern.

4. A filler arrangement film according to claim 1 or 2, wherein multiple fillers are regularly arranged within a group of fillers.

5. A filler array film according to claim 1 or 2, wherein fillers are not arranged in the recesses.

6. The filler arrangement film according to claim 1 or 2, wherein the recess penetrates the insulating resin layer for retaining the filler.

7. The filler array film according to claim 1 or 2, wherein at least one side of the insulating resin layer for retaining fillers is laminated with another insulating resin layer.

8. The filler arrangement film according to claim 7, wherein the recesses penetrate the insulating resin layer for retaining the fillers, and the protrusions are separated from other protrusions by the penetrating recesses.

9. The filler array film according to claim 7, wherein the other insulating resin layer is an insulating resin layer for forming a black matrix.

10. A method for manufacturing a filler array film according to claim 1, comprising the following steps A to C: (Process A) A step of forming an insulating resin layer for retaining fillers on a release film that has been subjected to a release treatment; (Process B) A step of forming recesses and protrusions on one side of an insulating resin layer for retaining fillers by applying a mold having recesses corresponding to the protrusions of a filler arrangement film to the insulating resin layer for retaining fillers and performing a heat press; and (Process C) A process of transferring fillers to the top surface of a protrusion by placing the filler-placed side of a filler transfer sheet, which has multiple fillers arranged on one side of the transfer substrate, opposite the top surface of the protrusion and pressing from the transfer substrate side; A method for manufacturing a filler array film having the following characteristics.

11. Following process C, the following process D: (Process D) A step of embedding each filler transferred to the top surface of a protrusion into a filler-retaining insulating resin layer such that at least a portion of it is embedded; A method for producing a filler array film according to claim 10, further comprising the above.

12. The manufacturing method according to claim 10 or 11, wherein the pressing die is a concave single sheet.

13. A connecting structure comprising a first article connected to a second article via a filler array film as described in claim 1.

14. The connection structure according to claim 13, wherein the first article is a transparent display substrate with transparent electrodes arranged on one side, the second article is a μLED with electrodes formed on one side, the filler arranged on the convex portion of the filler array film is conductive particles, and the filler array film itself functions as a conductive film or an anisotropic conductive film.

15. A method for manufacturing a connecting structure, characterized by sandwiching and pressing the filler array film described in claim 1 between a first article and a second article.

16. A method for manufacturing a connection structure according to claim 15, wherein the first article is a transparent display substrate with transparent electrodes arranged on one side, the second article is a μLED with electrodes formed on one side, the fillers arranged on the protrusions of the filler array film are conductive particles, and the filler array film itself functions as a conductive film or an anisotropic conductive film.

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