Filler array film

Abstract

To provide a filler array film in which fillers such as conductive particles are arranged in an insulating resin layer, capable of surely increasing the number of actually captured fillers at each connection portion to one or more even when there is a misalignment of about ±10% between a first article and a second article in a case in which a connection portion of a microscopic first article such as a μLED electrode is coupled to a connection portion of a second article such as an electrode of a substrate for a large screen TV through a filler.SOLUTION: In a filler array film 1 in which fillers 2 are arranged in an insulating resin layer 10, in an insulating resin layer 10, a plurality of first groups 3 formed of the plurality of fillers 2 is aggregated to form a second group 4, and the second groups 4 are regularly arranged. The closest distance L1 between the second groups 4 is greater than the closest distance L2 between the first groups, and the closest distance L2 between the first groups is greater than the closest distance L3 between the fillers in the first group.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a filler array film in which fillers are arranged in a resin layer, a method for connecting a minute first article to a second article such as a substrate using the filler array film, and a connection structure obtained by this method. Here, the minute first article can be a minute light-emitting element such as a mini-LED or a μLED. [Background technology]

[0002] μLED displays, which consist of tiny light-emitting elements called μLEDs arranged on a substrate, are expected to be a display or light source that can achieve thinner displays by eliminating the backlight required for liquid crystal displays, as well as wider color gamut, higher resolution, and lower power consumption.

[0003] Patent Document 1 describes a method for manufacturing a display with an array of μLEDs, in which a red, blue, and green μLED array formed on a carrier substrate is picked up by a transfer head, placed on a transfer destination substrate such as a display substrate, the μLED array and the transfer destination substrate are joined by soldering a solder layer, and then contact lines are formed on top of it using ITO or the like.

[0004] Furthermore, Patent Document 2 describes a method in which a μLED formed on a wafer is placed on a substrate, connected to the substrate using an anisotropic conductive film in which conductive particles are dispersed in an adhesive component such as a hydrogenated epoxy compound, and then the wafer is lifted off. According to the method using the anisotropic conductive film described in Patent Document 2, a display using μLEDs can be easily obtained.

[0005] Patent Document 3 describes a two-stage connection method for connecting an IC chip and an FPC using an anisotropic conductive film having a conductive particle arrangement layer with a conductive particle area occupancy rate of 35% or less in a plan view. This method uses a pulse heater type bonder to improve the efficiency of capturing conductive particles, and involves a first stage where the IC chip and FPC are pressed into the insulating resin layer of the anisotropic conductive film to temporarily fix the electrodes closer to the conductive particle arrangement layer, and a second stage where permanent bonding is performed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2015-500562 [Patent Document 2] Japanese Patent Publication No. 2017-157724 [Patent Document 3] Japanese Patent Publication No. 2019-216097 [Overview of the project] [Problems that the invention aims to solve]

[0007] As the size of μLEDs decreases to achieve higher resolution displays, and consequently the size of the LED electrodes also decreases, it becomes difficult to reliably capture conductive particles on the electrodes of individual μLEDs when using an anisotropic conductive film in which conductive particles are simply mixed into an insulating material.

[0008] In response to this, one approach is to use conductive particles with smaller particle sizes to increase the number density of conductive particles in conductive films and anisotropic conductive films.

[0009] However, if the particle size of the conductive particles is reduced, the conductive particles become more likely to move due to the flow of the resin material constituting the anisotropic conductive film during heating and pressurizing when connecting the μLED and the substrate via the anisotropic conductive film. Furthermore, in high-resolution displays, the space between electrodes is extremely narrow, raising concerns about the risk of conductive particles connecting between electrodes and causing a short circuit.

[0010] While it is conceivable to use a pulse heater type bonder as described in Patent Document 3 to suppress the movement of conductive particles during connection, even with this method, there is a limit to the area that can be connected in a single crimping, making it impossible to crimp large-area displays such as large-screen televisions all at once with anisotropic conductive film.

[0011] Therefore, the object of the present invention is to provide a filler array film in which fillers such as conductive particles are arranged in an insulating resin layer, which can reliably ensure that the actual number of fillers captured at each connection point is 1 or more, even if the alignment misalignment between the first and second articles is about ±10%, when connecting the connection point of a minute first article, such as the electrodes of a μLED, to the connection point of a second article, such as the electrodes of a substrate for a large-screen television, via fillers; and to provide a method for connecting a minute first article and a second article using such a filler array film, and a connection structure obtained by this method. [Means for solving the problem]

[0012] The inventors of the present invention have conceived that when connecting the connection portion of a minute first article, such as an electrode of a μLED, to the connection portion of a second article, such as an electrode of a substrate for a large-screen television, via fillers using a filler array film in which fillers such as conductive particles are arranged in an insulating resin layer, if the fillers in the filler array film form a first group at a position corresponding to the connection portion of the first article, multiple first groups gather to form a second group corresponding to the outer shape of the first article, and the second group is arranged in accordance with the arrangement of the first article, then unnecessary fillers that do not participate in the connection can be reduced as much as possible, and the resin flow during connection passes between the second groups and is less affected within the second group, so that the fillers constituting the first group are reliably captured between the connection portion of the first article and the connection portion of the second article. In addition, when the first article is a light-emitting element such as a μLED, the fillers do not obstruct the emission of light from the light-emitting element, and the luminous efficiency of the light-emitting device on which the light-emitting element is mounted is improved, and thus the present invention was completed.

[0013] That is, the present invention is a filler array film in which fillers are arranged in an insulating resin layer, in the insulating resin layer, a plurality of first groups formed by a plurality of fillers gather to form a second group, and the second group is regularly arranged, the closest distance between the second groups is larger than the closest distance between the first groups, and the closest distance between the first groups is larger than the closest distance between the fillers within the first group and provides a filler array film.

[0014] Further, the present invention is a method for manufacturing a connection structure in which a plurality of first articles are arranged on a second article, and the connection portions of the individual first articles and the connection portions of the second article are connected by heating or pressing through a filler array film in which fillers are arranged in an insulating resin layer, as the filler array film, in the insulating resin layer, a plurality of first groups formed by a plurality of fillers corresponding to the connection portions of the first article gather in correspondence with the outer shape of the first article to form a second group, and the second group is arranged in correspondence with the arrangement of the first article, the closest distance between the second groups is larger than the closest distance between the first groups, and the closest distance between the first groups is larger than the closest distance between the fillers within the first group and provides a method for manufacturing a connection structure using the filler array film.

[0015] Furthermore, the present invention is a connection structure having a connection portion where the connection portions of the individual first articles and the connection portions of the second article are connected via fillers in a state where a plurality of first articles are arranged on the second article, the fillers within a first group formed by a plurality of fillers constitute the connection portion, a second group formed by gathering a plurality of the first groups exists corresponding to the mounting positions of the first articles, the second group is arranged in correspondence with the arrangement of the first articles, the closest distance between the second groups is larger than the closest distance between the first groups, and the closest distance between the first groups is larger than the closest distance between the fillers within the first group Provide a connection structure.

Advantages of the Invention

[0016] When using the filler array film of the present invention, when connecting the connection part of a minute first article such as an electrode of a μLED to the connection part of a second article such as an electrode of a substrate for a large-screen television by heating or pressurizing through a filler array film in which fillers such as conductive particles are arranged in an insulating resin layer, one or more fillers are surely captured between the connection part of the first article and the connection part of the second article, and there is a low risk that the fillers are connected between adjacent connection parts of the first article or between connection parts of the second article. Therefore, the risk of short circuit when connecting electronic components such as μLEDs to a substrate can be reduced.

[0017] Further, when the first article is a light-emitting element such as a μLED, since the second group corresponding to the outer shape of the light-emitting element is arranged corresponding to the arrangement of the light-emitting elements, the emission of light from the light-emitting element is not obstructed by the second group. Therefore, the luminous efficiency of the light-emitting device in which the light-emitting element is mounted is improved.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is an arrangement diagram of fillers in the filler array film of the embodiment. [Figure 2] FIG. 2 is a correspondence diagram between the arrangement of fillers in the filler array film of the embodiment and the connection parts of articles to be connected with the filler array film. [Figure 3] FIG. 3 is a cross-sectional view taken along line A-A of the filler array film of the embodiment of FIG. 1.

Mode for Carrying Out the Invention

[0019] Hereinafter, the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals denote the same or equivalent components.

[0020] (Filler Arrangement) Figure 1 is a diagram showing the arrangement of fillers in a filler array film 1 according to one embodiment of the present invention. In this filler array film 1, conductive particles are arranged as fillers 2 in an insulating resin layer 10. Hereinafter, the filler array film 1 of the embodiment will be mainly described as an anisotropic conductive film, but the filler array film of the present invention can also be used as a conductive film for conductively connecting articles.

[0021] The filler array film of the present invention connects the connection points of individual first articles to the connection points of second articles by heating or pressurizing the first articles and second articles through the filler array film while multiple first articles are arranged on a second article. In this connected state, a filler is sandwiched between the connection points of individual first articles and second articles, and the opposing surfaces of the first and second articles are bonded together with an insulating resin layer.

[0022] In this embodiment, the filler array film 1 is used as an anisotropic conductive film to connect the first and second articles in an anisotropic conductive manner when the first article is a μLED, its electrodes are the connection points of the first article, and the second article is a substrate on which a wiring circuit for the μLED is formed, with its electrodes also being the connection points of the second article. This filler array film 1 may also be used as a conductive film.

[0023] As shown in Figure 2, each μLED 20 connected using the filler array film 1 of this embodiment has two electrodes 21 and is regularly arranged in a grid pattern on the wafer 22.

[0024] Regarding the external shape and size of the μLED20, for example, if the external shape is rectangular, its longest side is 200 μm or less, or less than 150 μm, or less than 50 μm, or less than 20 μm. More specifically, examples of rectangles include 10 μm × 20 μm, 7 μm × 14 μm, and 5 μm × 5 μm. Note that the external shape of the μLED20 is not limited to a rectangle; for example, it may be a rhombus.

[0025] Furthermore, the external shape and size of the electrode 21 are not particularly limited, but when the μLED is small, a rectangle with a long side of 5 μm to 50 μm and a short side of 3 μm to 40 μm can be used, and the spacing Ls between electrodes 21 within a single μLED 20 can be appropriately selected depending on the method of use. The lower limit is preferably 3 μm or more, more preferably 5 μm or more, for the convenience of the mounting process. There is no particular limit to the upper limit. In the case of elements that are larger than μLEDs or mini-LEDs and used alone, it may be 3000 μm or less. In the case of display applications, it may be 1000 μm or less, 500 μm or less, 150 μm or less, or 20 μm or less.

[0026] In the filler array film 1, multiple conductive particles (fillers) 2, positioned at locations corresponding to the individual electrodes (connections) 21 of the μLED (first item) 20, form a first group 3. Multiple particles of the first group 3 aggregate to form a second group 4, corresponding to the outer shape of the μLED 20. This second group 4 is arranged regularly to correspond to the arrangement of the μLED 20.

[0027] Here, the statement that the first group 3 is positioned to correspond to the electrodes 21 of the μLED 20 means that when a plurality of μLEDs 20 in a predetermined arrangement state and the filler arrangement film 1 are aligned, the electrodes 21 of each μLED 20 and the first group 3 overlap in a plan view, and the space Ls between the electrodes 21 of each μLED 20 and the space L2 between the first group 3 overlap. Preferably, the electrodes 21 are located within the first group 3, or one or more conductive particles 2 constituting the first group 3 overlap with the electrodes 21.

[0028] The arrangement of the second group 4 corresponds to the arrangement of the μLEDs 20, which means that, due to the alignment described above, each μLED 20 and the second group 4 overlap in a plan view, and the space between each μLED and the space L1 between the second group 4 overlap. Preferably, for each μLED 20, the total area of ​​the conductive particles 2 constituting the second group 4 that are outside the outer shape of the μLED 20 is within 50% of the outer shape of the μLED 20, and more preferably, all the conductive particles 2 constituting the second group 4 are located within the outer shape of each μLED 20.

[0029] Furthermore, when we say that group 24 is arranged in accordance with the arrangement of μLED20, we mean that the arrangement direction and arrangement pitch of group 24 are equal to the arrangement direction and arrangement pitch of μLED20.

[0030] Between groups 4 of the second group, it is desirable to have fewer conductive particles 2 in order to reduce appearance problems after mounting minute components on the filler array film 1. In particular, when the particle size of conductive particles 2 is less than 3 μm, it is desirable to have fewer aggregated or irregular conductive particles present between groups 4 of the second group.

[0031] As described above, the first group 3 of conductive particles in the filler array film 1 corresponds to the electrodes 21 of the μLED 20, and the second group 4 corresponds to the outer shape of the μLED 20. Therefore, if we define the nearest neighbor distance between the second groups 4 (i.e., the distance between a conductive particle constituting a certain second group and the conductive particle constituting the second group closest to that second group) as L1, the nearest neighbor distance between the first groups 3 (i.e., the distance between a conductive particle constituting a certain first group and the conductive particle constituting the first group closest to that first group) as L2, and the nearest neighbor distance between conductive particles 2 within the first group 3 as L3, L1>L2>L3 This is the result.

[0032] Since the first group 3 corresponds to the electrode 21 of the μLED 20, a group of conductive particles with the same shape and parallel arrangement as the number of electrodes (2) of the μLED can be considered as a single second group 4. When this second group 4 is in parallel, it can be considered that the first group 3 consists of conductive particles that are relatively densely packed at a distance L3, the second group 4 consists of particles that are spaced apart at a distance L2, and the second group 4 particles are spaced apart at a distance of L1. Therefore, the conductive particles (fillers) arranged on the film do not exist uniformly on the surface, but rather groups with different distance rules exist on the surface. For this reason, although L1 is defined as the "neighboring distance between second groups" as described above, it is practically preferable for there to be (mixed) second group distances that are larger than this.

[0033] When multiple μLEDs 20 arranged on a wafer 22 are connected to a substrate by heating and pressurizing via a filler array film 1, L1 and L2 are appropriately determined according to the external shape, array pitch, and inter-electrode distance of the μLEDs 20, in order to minimize the influence of the resin flow of the insulating resin layer 10 of the filler array film 1 on the arrangement of conductive particles 2 in the second group 4. Furthermore, L1 and L2 are also determined by the design of the μLEDs and mini-LEDs, and for example, in order to adjust the resolution for display and the performance as a light source, the lower limit should be 10 μm or more, and the upper limit can be 3000 μm or less, 1000 μm or less, or 500 μm or less.

[0034] The area of ​​the contour shape of the second group 4 that circumscribes the outer conductive particles 2 among the conductive particles 2 constituting the second group 4 is preferably such that it satisfies the following ratio with respect to the outer shape of the corresponding μLED 20. That is, reducing the lower limit of the ratio between the area of ​​the contour shape of the second group 4 and the area of ​​the outer shape of the μLED 20 makes it easier for the conductive particles 2 to fit within the outer shape of the μLED 20. This ratio is preferably 0.1 times or more, more preferably 0.2 times or more, and even more preferably 0.5 times or more, in order to make it easier for the electrodes to capture the conductive particles. On the other hand, increasing the upper limit avoids concerns about insufficient conductive particles being captured by the electrodes, but may impair transparency and aesthetics, so it is preferably 1.5 times or less, more preferably 1.3 times or less, and even more preferably 1.2 times or less.

[0035] Furthermore, since a deviation of approximately ±10% is permitted in the alignment between the first group 3 of the filler array film 1, the electrodes 21 of the μLED 20, and the electrodes of the substrate, the area of ​​the contour shape of the first group 3 that circumsects the conductive particles on the outer periphery of the conductive particles 2 constituting the first group 3 may be 0.5 to 1.8 times the area of ​​the corresponding electrodes 21 of the μLED 20, and preferably 0.8 to 1.2 times. Within this range, there is an adequate number of conductive particles, so both capture and short circuits can be achieved, and a good capture state is easily obtained and confirmed.

[0036] In the present invention, a single second group 4 can contain a number of first groups 3 corresponding to the number of connection parts that a single first article has, and in particular, it can contain three or fewer first groups 3, and in this embodiment, there are two first groups 3.

[0037] The relationship between the nearest neighbor distance L3 between conductive particles within the first group 3 and the average particle diameter D of the conductive particles 2 is expressed as the ratio L3 / D, where the lower limit is preferably 0.3 or more, more preferably 0.5 or more, and the upper limit is preferably 4 or less, more preferably 3 or less.

[0038] The arrangement of conductive particles 2 in the first group 3 may be random or regular, but from the viewpoint of improving the capture ability of conductive particles at each electrode 21, a planar lattice pattern having one or more alignment axes in which conductive particles are arranged at a predetermined pitch in a predetermined direction is preferred. Examples include rhombic lattices, hexagonal lattices, square lattices, rectangular lattices, and parallelepiped lattices. Furthermore, there may be regions with different planar lattice patterns.

[0039] On the other hand, in this invention, the average number density of fillers across the entire surface of the filler array film 1 and the average number density of fillers in the first group 3 are designed according to the object on which the filler array film is used. For example, the lower limit of the average number density across the entire surface is 500 pieces / mm if a sparse state is preferred. 2 The above is preferable, and if a dense state is preferred, then preferably 20,000 pieces / mm 2 More preferably 40,000 pieces / mm 2 That's all.

[0040] The lower limit of the average number density of fillers in group 1, subgroup 3 is preferably 50,000 pieces / mm². 2 More than 500,000 pieces / mm 2 The above is true, and the upper limit of the average number density is preferably 1,500,000 pieces / mm 2 More preferably 1,000,000 pieces / mm 2 The following applies:

[0041] The average number density of the space fillers between the second group 4 is 1000 pieces / mm 2 The following is preferable, and more preferably substantially zero.

[0042] Depending on the design of the object, it may exceed the above-mentioned lower and upper limit ranges.

[0043] The average filler area occupancy rate over the entire surface of the filler array film 1 and the average filler area occupancy rate in the first group 3 follow the same concept as the average number density. For example, when a small particle size and a dense state are preferable depending on the object using the filler array film 1, the average filler area occupancy rate in the first group 3 can be, for example, 5% or more, 8% or more, 25% or more, and can also be 85% or less, 50% or less. Here, the filler area occupancy rate means the conductive particle area occupancy rate in this embodiment, and is the number density (pieces / mm 2 ) of conductive particles in the plan view of the filler array film 1 × the average plan view area of one conductive particle (mm 2 / piece) × 100. When the filler array film is made into extremely small pieces, it refers to the number density measured in the state before fragmentation.

[0044] In addition to observing and obtaining the number density of conductive particles using a metallurgical microscope, it may also be obtained by measuring the observation image with image analysis software (for example, WinROOF (Miyaya Trading Co., Ltd.), A-Image-kun (registered trademark) (Asahi Kasei Engineering Co., Ltd.), etc.). The number of conductive particles is measured as the number observed on the filler array film.

[0045] (Filler) In this embodiment, the particle size of the conductive particles 2 used as filler is not particularly limited, but the lower limit of the particle size is preferably 1 μm or more. The upper limit of the particle size is preferably 50 μm or less, and more preferably 20 μm or less, from the viewpoint of the trapping efficiency of the conductive particles in the connecting structure. Depending on the size of the electrode, the particle size of the conductive particles may be required to be less than 3 μm, preferably less than 2.5 μm, and more preferably less than 2 μm. If the particle size is less than 1 μm, it may be treated as an aggregate of 1 μm or larger.

[0046] The average particle size can be the value measured using an image-type particle size analyzer (for example, the FPIA-3000, manufactured by Malvern Panalytical). In this case, the number of particles is preferably 1000 or more, more preferably 2000 or more.

[0047] Furthermore, the type of conductive particles can be appropriately selected from among the conductive particles used in known anisotropic conductive films. For example, 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 also be used in combination. Among these, metal-coated resin particles are preferred because, after connection, the resin particles repel each other, making it easier to maintain contact with the terminals and resulting in stable conductivity. In addition, the surface of the conductive particles may be subjected to an insulating treatment using known techniques that does not impair the conductivity characteristics.

[0048] In the filler array film of the present invention, the fillers are appropriately selected from inorganic fillers (metal particles, metal oxide particles, metal nitride particles, etc.), organic fillers (resin particles, rubber particles, etc.), and fillers containing a mixture of organic and inorganic materials (for example, particles with a resin core and a metal-plated surface (metal-coated resin particles), conductive particles with insulating fine particles attached to their surface, conductive particles with an insulating treatment applied to their surface, etc.) according to the performance required for the application, such as hardness and optical performance.

[0049] For example, when a filler array film is used as a conductive film or an anisotropic conductive film, conductive particles are included as fillers. Depending on the application of the filler array film, fillers other than conductive particles may also be used.

[0050] When filler array films are used for adjusting the color development of micro-optical elements such as μLEDs, or as black matrices in color displays, known dyes, pigments, light-scattering particles, etc., may be used as fillers. When the filler array film is used as an optical film or a matte film, silica fillers, titanium oxide fillers, styrene fillers, acrylic fillers, melamine fillers, and various titanates can be used. For capacitor films, titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, calcium titanate, strontium titanate, barium titanate, barium zirconate titanate, lead zirconate titanate, and mixtures thereof can be used. For adhesive films, polymer-based rubber particles, silicone rubber particles, etc., may be included.

[0051] (Cross-sectional structure of filler array film) Figure 3 is a cross-sectional view AA of the filler array film 1 shown in Figure 1. In the region of group 3 of the filler array film 1 of this embodiment, conductive particles 2 are arranged in the insulating resin layer 10.

[0052] The insulating resin layer 10 may consist of a single insulating resin layer or a laminate of multiple resin layers. Preferably, the positions of the ends of the conductive particles 2 substantially coincide with one face of the layer. "Subjectively coincide" means, for example, including an error of about ±10% of the particle diameter. When the insulating resin layer is a laminate of multiple resin layers, for example, as shown in Figure 3, it can consist of a high-viscosity binder resin layer 11 that holds the conductive particles 2 and an adhesive layer 12 with lower viscosity than the high-viscosity binder resin layer 11. The resins constituting this high-viscosity binder resin layer 11 and adhesive layer 12 can be, for example, the same as the binder and adhesive layers constituting the insulating resin layer described in Patent Document 3. Different fillers may be placed on different layers and laminated.

[0053] The insulating resin layer 10 may contain, as needed, rubber components, inorganic fillers, silane coupling agents, diluent monomers, fillers, softeners, colorants, flame retardants, thixotropic agents, and the like.

[0054] Rubber components may be added to prevent warping and distortion of the connecting structure. The rubber component is not particularly limited as long as it is an elastomer with high cushioning (shock absorption) properties. Specific examples include acrylic rubber, silicone rubber, butadiene rubber, and polyurethane resin (polyurethane elastomer).

[0055] The thickness of the insulating resin layer 10 is set such that, when the μLED 20 and the substrate are connected by heating and pressurizing them via the filler array film 1, unwanted resin flow occurs in the insulating resin layer, and resin overflow and blocking occurs when the filler array film 1 is wound into a coil. The lower limit of the layer thickness is 0.6 times or more, preferably 0.9 times or more, and more preferably 1 time or more, the average particle diameter of the conductive particles 2, and the upper limit is 3 times or less, preferably 2 times or less, and more preferably 1.5 times or less. If the thickness of the insulating resin layer 10 is less than 0.6 times the average particle diameter of the conductive particles 2, the conductive particles 2 will be exposed from the insulating resin layer 10, making it difficult to temporarily attach the filler array film 1 to the μLED 20 or the substrate when connecting the μLED 20 and the substrate using the filler array film 1. On the other hand, if the ratio exceeds 3, excessive resin flow occurs when the μLED20 is connected to the substrate, causing the conductive particles 2 to be carried away by the resin flow, and reducing the ability of the electrodes to capture the conductive particles 2.

[0056] Furthermore, for manufacturing reasons that take into account the arrangement of particles, the thickness of the insulating resin layer 10 is preferably 2 μm or more at the lower limit, and more preferably 3 μm or more. As for the upper limit, since excessively large layer thickness can easily cause misalignment during connection, it is preferably 32 μm or less, more preferably 20 μm or less, and even more preferably 8 μm or less.

[0057] Furthermore, in the present invention, the μLED itself is small, and the size of the μLED and the size of the conductive particles are closer than in conventional designs. There is a concern that the μLED may be prone to misalignment, but it is preferable that the connection structure avoids this misalignment. For these reasons, the thickness of the insulating resin layer 10 is required to fall within the above range.

[0058] (Method for manufacturing filler array film) The filler array film 1 can be manufactured in the same manner as known anisotropic conductive films, except that the conductive particles are arranged in a specific configuration as described above. For example, similar to the method for manufacturing an anisotropic conductive film described in Patent Document 3, first, a mold is prepared in which recesses corresponding to the arrangement pattern of the conductive particles are formed, the conductive particles 2 are filled into the mold, a high-viscosity binder resin layer 11 formed on a release film is bonded to it, the conductive particles 2 are pressed into the high-viscosity binder resin layer 11 and transferred, and an adhesive layer 12 is laminated onto the transferred surface.

[0059] (Connection method using filler array film) A method for connecting the electrodes of multiple μLEDs 20 to the electrodes of a substrate when multiple μLEDs 20 are regularly arranged on a wafer 22 using a filler array film 1 involves first aligning and attaching the filler array film 1 to the electrodes of the substrate, then aligning and attaching the filler array film 1 to the μLEDs 20 arranged on the wafer 22, and finally heating and pressing to connect the electrodes of the μLEDs 20 to the electrodes of the substrate. In this case, the connection may be made by heating and pressing in a two-stage method as described in Patent Document 3. Alternatively, if the conductive particles are solder particles or the like, the connection may be made by reflow soldering.

[0060] During this heating and pressurizing process, the insulating resin layer 10 of the filler array film 1 flows and fills the gap between the opposing surfaces of the μLED 20 and the substrate, and hardens to bond the μLED 20 and the substrate. At this time, the fluidity of the resin is high between the second groups 4 where conductive particles are not placed, and within the second groups 4, the fluidity of the resin is lower than between the second groups 4 themselves. Therefore, the conductive particles 2 of the first group 3, which are positioned within the second group 4 corresponding to the electrodes of the μLED 20, are less affected by the resin flow between the second groups 4 themselves, and the electrodes 21 of each μLED 20 can reliably capture the conductive particles 2.

[0061] Furthermore, within the second group 4, the first group 3 members are arranged with a distance L2 between them corresponding to the arrangement of the electrodes 21, thus suppressing the occurrence of short circuits between the electrodes 21 within a single μLED 20.

[0062] In addition, in the filler array film 1, since there are no conductive particles 2 between the second group 4, the light emitted by the μLED 20 after connection to the substrate is not blocked by the conductive particles 2 in between. Therefore, the luminous efficiency of the light-emitting device on which the μLED is mounted is improved compared to when a filler array film with conductive particles uniformly present across the entire film surface is used.

[0063] The filler array film may also be in the form of individual pieces. The size of the individual pieces can be designed to suit the object, but for example, one side can be 5 μm or more and 150 m or less. This is expected to allow for applications such as adjusting color and light, which will be described later. That is, the first and second articles may be connected with the individual pieces of film, or the film may be placed only on the electrodes in the form of solid pieces. Individual pieces can be formed by making cuts using mechanical methods, chemical methods, lasers, etc. The cuts do not need to be deep enough to reach the substrate, and half-cuts are acceptable.

[0064] The temporary attachment of the filler array film, film transfer, and mounting of the μLEDs onto the substrate can be carried out using known methods such as stamping materials or laser-based methods (laser lift-off method), or methods that apply thereto (for example, methods described in Japanese Patent Publication No. 9-124020, Japanese Patent Publication No. 2011-76808, Japanese Patent No. 6636017, Japanese Patent No. 6187665, etc.), and are not particularly limited as long as they can achieve the effects of the invention.

[0065] (Connection structure) In the example, the connection structure between the μLED 20 and the substrate, connected using the filler array film 1 in the manner described above, has filler 2 in the first group 3 forming the connection point between the electrode 21 of the μLED 20 and the electrode of the substrate. Although the example is described using a μLED as an example, the connection structure in the present invention may be a mini-LED.

[0066] As described above, the influence of resin flow during connection does not significantly affect the arrangement of conductive particles 2 within the second group 4. Therefore, similar to before connection, in the planar arrangement of the filler, the second group, which is a collection of multiple first groups, exists corresponding to the mounting position of the μLEDs, and the second group is arranged corresponding to the arrangement of the μLEDs. Furthermore, considering all conductive particles, regardless of whether they constitute a connection point or not, if we define the nearest neighbor distance between second groups after connection as L1', the nearest neighbor distance between first groups after connection as L2', and the closest proximity distance between conductive particles as L3', L1'>L2'>L3' This relationship is maintained.

[0067] This connection structure exhibits improved luminous efficiency compared to a connection structure that connects a μLED to a substrate using a filler array film in which conductive particles are uniformly distributed across the entire film surface, as described above. Furthermore, it has a high ability to capture conductive particles at each electrode, resulting in a reduced rate of short circuits.

[0068] The connection method using the filler array film of the present invention and the connection structure obtained thereby have been described above based on the case in which the first item is a μLED, the second item is a substrate on which the wiring circuit of the μLED is formed, and the filler of the filler array film is conductive particles. However, the present invention is not limited thereto.

[0069] For example, the first item may be a light-scattering film, a black matrix layer, etc., the second item may be a transparent substrate (a substrate on which μLEDs are mounted), etc., and the filler may be silica or black-colored particles, etc., to adjust the color of the connecting structure between the first and second items. [Examples]

[0070] The present invention will be described in detail below based on examples. Examples 1-3, Comparative Examples 1, 2

[0071] (Fabrication of anisotropic conductive films) A resin was mixed according to the resin composition shown in Table 1, applied to a release film, and dried (60°C, 3 minutes) to obtain an adhesive film.

[0072] [Table 1]

[0073] On the other hand, a mold having recesses for filling conductive particles (average particle diameter 2.2 μm or 3.2 μm, 0.2 μm Ni-plated resin particles, Sekisui Chemical Co., Ltd.) was prepared in the same manner as described in Japanese Patent Publication No. 6187665, with the conductive particles arranged in the configuration shown in Table 2. The conductive particles were then filled into the recesses, the adhesive film shown in Table 1 was placed over it, and the conductive particles were pressed into the adhesive film to produce an anisotropic conductive film.

[0074] [Table 2]

[0075] (Evaluation of anisotropic conductive films) The particle trapping ability, insulating properties, and visible light transmittance of the anisotropic conductive films of Examples 1-3 and Comparative Examples 1 and 2 were evaluated as follows. The results are shown in Table 2.

[0076] (i) Particle trapping ability The anisotropic conductive films of Examples 1-3 and Comparative Examples 1 and 2 were attached to ITO / NdMo patterned glass, and an evaluation IC chip modeled after a μLED was heat-pressed onto it (reached temperature 150°C, pressurized 30 MPa, 10 seconds) to obtain a mounted assembly. This evaluation IC chip has an electrode layout in which two 10 μm × 10 μm bumps (with a 7 μm space between bumps) are arranged at a 30 μm pitch on approximately one surface of a 1.5 cm × 1.5 cm area.

[0077] By observing 100 bumps in this implementation, the number of conductive particles trapped in each bump was measured. The lowest number among these 100 bumps was used for evaluation according to the following criteria.

[0078] A: 5 or more B: 3~4 pieces C: 1~2 pieces D:0 pieces

[0079] (ii) Insulation The conductivity resistance was measured for the 100 bump spaces of the above-mentioned implementation, and 10 7 A value of Ω or less was determined to be a short. The number of shorts was evaluated according to the following criteria.

[0080] A: No short B: Short 1 piece C: 2 short pieces D: 3 or more shorts

[0081] (iii) Visible light transmittance The visible light transmittance (400-700 nm) of the anisotropic conductive films of Examples 1-3 and Comparative Examples 1 and 2 was measured, and the average transmittance (measurement area 10 mm x 10 mm) was evaluated according to the following criteria. In this case, the anisotropic conductive films were measured after being attached to a substrate, left at 200°C for 1 minute, and cured. This allows us to see how the resin that has seeped out of the connecting structure affects the result.

[0082] A: 50% or more B: 35% or more C: 20% or more D: Less than 20%

[0083] Table 2 shows that when an anisotropic conductive film is used in the example in which conductive particles are unevenly distributed on the bumps of a μ-chip or μ-LED, excellent evaluations of B or higher are obtained for particle capture, insulation, and visible light transmittance. [Explanation of Symbols]

[0084] 1 Filler array film 2. Filler, conductive particles 3 Group 1 4 Group 2 10 Insulating resin layer 11. High-viscosity binder resin layer 12 Adhesive layer 20 1st article, μLED 21 Electrode (connection part) 22 wafers L1: Distance between two groups of the same group L2: Distance between the first group of neighbors L3: Distance between fillers within the first group Ls μLED electrode distance

Claims

1. A filler array film having fillers arranged in an insulating resin layer, used for connecting a plurality of connection parts of a first article and a connection part of a second article, In the insulating resin layer, a first group is formed by a plurality of fillers arranged at positions corresponding to individual connection parts of the first article, and a second group is formed by a plurality of first groups aggregating in a manner corresponding to the outer shape of the first article. The second group is arranged regularly in accordance with the arrangement of multiple first articles. The nearest-neighbor distance between the second group is greater than the nearest-neighbor distance between the first group, and the nearest-neighbor distance between the first group is greater than the nearest-neighbor distance between fillers within the first group. Filler array film.

2. The filler array film according to claim 1, wherein one second group is formed of three or fewer first groups.

3. The average number density of fillers across the entire filler array film is 20,000 pieces / mm². 2 More than 1,500,000 pieces / mm 2 The filler array film according to claim 1 or 2, which is as follows:

4. A filler array film according to any one of claims 1 to 3, wherein the average filler occupancy rate across the entire surface of the filler array film is 25% or more and 50% or less.

5. A filler array film according to any one of claims 1 to 4, wherein the ratio L3 / D of the nearest neighbor distance L3 between fillers to the average particle diameter D of the fillers is 0.3 or more and 4 or less.

6. A filler arrangement film according to any one of claims 1 to 5, wherein the thickness of the insulating resin layer is 0.6 times or more and 3 times or less the average particle diameter of the filler.

7. A filler array film according to any one of claims 1 to 6, wherein the filler is conductive particles.

8. A method for manufacturing a connection structure, in which multiple first articles are arranged on a second article, and the connection portions of individual first articles and the connection portions of second articles are connected by heating or pressurizing them via a filler arrangement film in which fillers are arranged in an insulating resin layer, As a filler array film, A method for manufacturing a connection structure, using a filler arrangement film in which a first group is formed by a plurality of fillers arranged in an insulating resin layer at positions corresponding to individual connection parts of a first article, a plurality of the first groups gather together to form a second group corresponding to the outer shape of the first article, the second group is arranged regularly corresponding to the arrangement of the first article, the nearest neighbor distance between the second groups is greater than the nearest neighbor distance between the first groups, and the nearest neighbor distance between the first groups is greater than the nearest neighbor distance between fillers within the first group.

9. The manufacturing method according to claim 8, wherein the first article is a μLED and the second article is a substrate.

10. A connection structure having connection points in which, in a state in which multiple first articles are arranged on a second article, the connection points of each first article and the connection points of the second article are connected via fillers, A first group is formed by a plurality of fillers arranged at positions corresponding to individual connection parts of the first article, and the fillers within the first group constitute the connection points. Multiple first groups combine in a manner corresponding to the mounting position of the first article to form a second group. The second group is arranged regularly in accordance with the arrangement of the first item. The nearest-neighbor distance between the second group is greater than the nearest-neighbor distance between the first group, and the nearest-neighbor distance between the first group is greater than the nearest-neighbor distance between fillers within the first group. A connection structure.

11. The connection structure according to claim 10, wherein the first article is a μLED and the second article is a substrate.

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