Filler alignment film

Abstract

This invention provides a filler arrangement film in which, when a filler arrangement film consisting of conductive particles or other fillers arranged in an insulating resin layer is used to connect the connection portion of a tiny first item such as the electrode of a μLED to the connection portion of a second item such as the electrode of a large-screen television substrate through the filler, even if the alignment deviation between the first item and the second item is about ±10%, the actual capture number of the filler in each connection portion can be reliably made to be 1 or more. In this filler arrangement film (1), fillers (2) are arranged in an insulating resin layer (10), and multiple first groups (3) formed by multiple fillers (2) in the insulating resin layer (10) are aggregated to form a second group (4), which is arranged regularly. 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 within the first group.

Description

Technical Field

[0001] This invention relates to a filler arrangement film formed by arranging fillers in a resin layer, a method for connecting a tiny first article to a second article such as a substrate using the filler arrangement film, and a connection structure obtained by the method. Examples of tiny first articles include, for instance, miniature light-emitting elements such as sub-millimeter LEDs (Mini LEDs) and μLEDs. Background Technology

[0002] μLED displays, which are formed by arranging tiny light-emitting elements μLEDs on a substrate, can eliminate the backlight required for liquid crystal displays, thereby enabling thin-film displays. They are also expected to be displays or light sources that can achieve wide color gamut, high resolution, and low power consumption.

[0003] As a method for manufacturing a display composed of arranged μLEDs, Patent Document 1 describes a method in which a red, blue, and green μLED array formed on a carrier substrate is picked up by a transport head, placed on a transfer target substrate such as a display substrate, the μLED array is joined to the transfer target substrate by welding a solder layer, and then contact lines are formed thereon by ITO or the like.

[0004] Furthermore, Patent Document 2 describes a method in which a μLED formed on a wafer is disposed on a substrate, connected to the substrate using an anisotropic conductive film, and then the wafer is lifted off. The anisotropic conductive film is formed by dispersing conductive particles in an adhesive component using a hydrogenated epoxy compound or similar material. According to the method using an 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: when connecting an IC chip and an FPC using an anisotropic conductive film with a conductive particle arrangement layer having a conductive particle area occupancy rate of less than 35% from a top view, in order to improve the conductive particle capture efficiency, a pulse heater type bonding machine is used. In the first stage, the IC chip and FPC are pressed into the insulating resin layer of the anisotropic conductive film to temporarily fix the electrodes close to the conductive particle arrangement layer. In the second stage, formal pressing is performed.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Publication No. 2015-500562

[0009] Patent Document 2: Japanese Patent Application Publication No. 2017-157724

[0010] Patent Document 3: Japanese Patent Application Publication No. 2019-216097 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] As the size of μLEDs decreases to achieve higher resolution in displays, the size of the LED electrodes also decreases. When using anisotropic conductive films made by mixing only conductive particles in an insulating material, it becomes difficult to reliably capture the conductive particles at the electrodes of each μLED.

[0013] To address this, we consider using small-sized conductive particles to increase the number density of conductive particles in conductive films and anisotropic conductive films.

[0014] However, if the particle size of the conductive particles is reduced, the conductive particles are prone to move due to the flow of the resin material constituting the anisotropic conductive film when heating and pressurizing the μLED and the substrate through the anisotropic conductive film. Moreover, since the spacing between electrodes is extremely narrow in high-resolution displays, there is a risk of short circuits caused by conductive particles connecting between electrodes.

[0015] In order to suppress the movement of conductive particles during the connection, the pulse heater type bonding machine described in Patent Document 3 was also considered. However, even with this method, the area that can be connected in one crimping is limited, so it is not possible to crimp large-area displays such as large-screen TVs in one go using anisotropic conductive films.

[0016] Therefore, the present invention provides a filler arrangement film in which a connection portion of a tiny first item, such as an electrode of a μLED, is connected to a connection portion of a second item, such as an electrode of a large-screen television substrate through a filler, using a filler arrangement film in which a conductive particle or the like is arranged in an insulating resin layer. In this case, even if the alignment deviation between the first item and the second item is about ±10%, the actual capture number of the filler in each connection portion can be reliably made to be 1 or more. The present invention also provides a method for connecting tiny first and second items using the filler arrangement film described above, and a connection structure obtained by the method.

[0017] Solution for solving the problem

[0018] The inventors realized the following facts and thus completed the present invention: A filler film, consisting of conductive particles or other fillers arranged in an insulating resin layer, is used to connect the connecting portion of a tiny first item, such as the electrode of a μLED, to the connecting portion of a second item, such as the electrode of a large-screen television substrate, through the filler. In this case, the filler in the filler film forms a first group at the position corresponding to the connecting portion of the first item, and multiple first groups are aggregated to form a second group corresponding to the shape of the first item. When the second group is arranged corresponding to the arrangement of the first item, unnecessary filler that does not participate in the connection can be minimized. Furthermore, the resin flow during connection passes between the second groups without easily affecting the second group. Thus, the filler constituting the first group is reliably trapped between the connecting portion of the first item and the connecting portion of the second item. Moreover, when the first item is a light-emitting element such as a μLED, the filler does not obstruct light emission from the light-emitting element, improving the luminous efficiency of the light-emitting device with the light-emitting element.

[0019] That is, the present invention provides a filler arrangement film, which is a filler arrangement film formed by arranging fillers in an insulating resin layer. In the insulating resin layer, a first group formed by multiple fillers is aggregated to form a second group. The second groups are arranged regularly, and the closest distance between the second groups is greater than the closest distance between the first groups. The closest distance between the first groups is greater than the closest distance between the fillers in the first group.

[0020] Furthermore, the present invention provides a method for manufacturing a connecting structure, wherein the method comprises manufacturing a connecting structure by heating or pressurizing the connecting portions of each first article and the connecting portions of the second article in a state in which multiple first articles are arranged on a second article, with the connecting portions of the first articles and the connecting portions of the second articles separated by a filler arrangement film in which fillers are arranged in an insulating resin layer. The filler arrangement film used is as follows: in the insulating resin layer, a first group formed by multiple fillers is assembled in a manner corresponding to the connecting portions of the first articles, and a second group is formed by multiple fillers corresponding to the shape of the first articles. The second group is arranged in a manner corresponding to the arrangement of the first articles, and the closest distance between the second groups is greater than the closest distance between the first groups, and the closest distance between the first groups is greater than the closest distance between the fillers in the first group.

[0021] Furthermore, the present invention provides a connecting structure having the following connecting parts: when multiple first articles are arranged on a second article, the connecting parts of each first article and the connecting parts of the second article are connected by a filler, the connecting parts are formed by fillers in a first group of multiple fillers, a second group formed by multiple first groups exists corresponding to the mounting position of the first articles, the second group is arranged corresponding to the arrangement of the first articles, the closest distance between the second groups is greater than the closest distance between the first groups, and the closest distance between the first groups is greater than the closest distance between the fillers in the first group.

[0022] Invention Effects

[0023] When the filler arrangement film of the present invention is used, heating or pressurizing the filler arrangement film, in which conductive particles or other fillers are arranged in an insulating resin layer, connects the connection portion of a tiny first item such as the electrode of a μLED to the connection portion of a second item such as the electrode of a large-screen television substrate. In this case, one or more fillers can be reliably trapped between the connection portion of the first item and the connection portion of the second item, and the risk of filler interconnection between adjacent connection portions of the first item or between connection portions of the second item is low. Therefore, the risk of short circuits when connecting electronic components such as μLEDs to the substrate can be reduced.

[0024] Furthermore, when the first element is a light-emitting element such as a μLED, the second group, which corresponds to the shape of the light-emitting element, is arranged in a manner corresponding to the arrangement of the light-emitting elements, so that the light emitted from the light-emitting elements is not obstructed by the second group. As a result, the luminous efficiency of the light-emitting device equipped with the light-emitting elements is improved. Attached Figure Description

[0025] Figure 1 This is a diagram showing the configuration of the packing material in the packing arrangement membrane of the embodiment.

[0026] Figure 2 This is a diagram showing the correspondence between the arrangement of the filler in the filler arrangement membrane of the embodiment and the connection portion of the article connected by the filler arrangement membrane.

[0027] Figure 3 yes Figure 1 A-A sectional view of the packing arrangement membrane of the embodiment. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals in the drawings denote the same or equivalent constituent elements.

[0029] (Packaging configuration)

[0030] Figure 1 This is a diagram showing the arrangement of the filler in a filler-arranged film 1 according to an embodiment of the present invention. The filler-arranged film 1 is a film formed by arranging conductive particles as filler 2 in an insulating resin layer 10. Hereinafter, the filler-arranged film 1 of this embodiment will be described primarily as an anisotropic conductive film, but the filler-arranged film of the present invention can also be used as a conductive film for electrically connecting articles to each other.

[0031] With regard to the filler arrangement membrane of the present invention, in a state in which a plurality of first articles are arranged on a second article, the first articles and the second articles are heated or pressurized through the filler arrangement membrane, thereby connecting the connecting portion of each first article to the connecting portion of the second article. In this connected state, filler is sandwiched between the connecting portion of each first article and the connecting portion of the second article, and the opposing surfaces of the first articles and the second articles are bonded to each other by an insulating resin layer.

[0032] In this embodiment, the filler arrangement film 1 can be used as an anisotropic conductive film for anisotropically conductively connecting the first and second articles when the first article is configured as a μLED, its electrodes are configured as the connecting portion of the first article, and the second article is configured as a substrate for forming a wiring circuit for the μLED, with its electrodes configured as the connecting portion of the second article. This filler arrangement film 1 can also be used as a conductive film.

[0033] like Figure 2 As shown, each μLED 20 connected using the filler arrangement film 1 of this embodiment has two electrodes 21, which are arranged in a grid pattern on the wafer 22.

[0034] Regarding the shape and size of μLED20, for example, in the case of a rectangular shape, its long side is less than 200μm, or less than 150μm, or less than 50μm, or less than 20μm. More specifically, examples include rectangles of 10μm×20μm, 7μm×14μm, and 5μm×5μm. It should be noted that the shape of μLED20 is not limited to rectangles; for example, it can also be rhomboid.

[0035] Furthermore, the shape and size of the electrode 21 are not particularly limited. When the μLED is small, a rectangle with a long side of 5μm to 50μm and a short side of 3μm to 40μm can be used. The spacing Ls between the electrodes 21 within a μLED 20 can be appropriately selected according to the application method. For ease of installation, the lower limit is preferably 3μm or more, more preferably 5μm or more. The upper limit is not particularly limited. For components larger than μLEDs or sub-millimeter LEDs and used independently, the spacing can be 3000μm or less. For display applications, the spacing can be 1000μm or less, 500μm or less, 150μm or less, or 20μm or less.

[0036] In the filler film 1, a plurality of conductive particles (fillers) 2 disposed at positions corresponding to the respective electrodes (connections) 21 of the μLED (first article) 20 form a first group 3. The plurality of first groups 3 are assembled in a manner corresponding to the shape of the μLED 20, thereby forming a second group 4. The second group 4 is arranged regularly in a manner corresponding to the arrangement of the μLED 20.

[0037] Here, the first group 3 being positioned corresponding to the electrode 21 of the μLED 20 means that, when the multiple μLEDs 20 in a specified arrangement are aligned with the filler film 1, the electrode 21 of each μLED 20 overlaps with the first group 3 when viewed from above, and the interval Ls between the electrodes 21 of each μLED 20 overlaps with the interval L2 between the first group 3. Preferably, the electrode 21 is located within the first group 3, or one or more of the conductive particles 2 constituting the first group 3 overlap with the electrode 21.

[0038] The arrangement of the second group 4 and the μLED 20 is such that, through the above alignment, each μLED 20 overlaps with the second group 4 when viewed from above, and the spacing between each μLED overlaps with the spacing L1 between the second group 4. Preferably, with respect to the μLED 20, among the conductive particles 2 constituting the second group 4, the total area of ​​the conductive particles 2 that deviate from the shape of the μLED 20 is within 50% of the area of ​​the shape of the μLED 20. More preferably, all the conductive particles 2 constituting the second group 4 are located within the shape of each μLED 20.

[0039] Furthermore, the arrangement of the second group 4 and μLED20 in a corresponding manner means that the arrangement direction and spacing of the second group 4 are the same as those of the μLED20.

[0040] In order to reduce the appearance problems of mounting tiny components on the filler arrangement film 1, it is ideal to have fewer conductive particles 2 between the second group 4, and especially ideal to have fewer agglomerates or irregular conductive particles between the second group 4 when the particle size of the conductive particles 2 is less than 3 μm.

[0041] As described above, the first group 3 of conductive particles in the filler arrangement film 1 corresponds to the electrode 21 of the μLED20, and the second group 4 corresponds to the shape of the μLED20. Therefore, the closest distance between the second groups 4 (i.e., the distance between the conductive particles constituting a certain second group and the conductive particles constituting the second group closest to that second group) is set as L1, the closest distance between the first groups 3 (i.e., the distance between the conductive particles constituting a certain first group and the conductive particles constituting the first group closest to that first group) is set as L2, and the closest distance between the conductive particles 2 in the first group 3 is set as L3. In this case, L1 > L2 > L3.

[0042] The first group 3 corresponds to the electrode 21 of the μLED20. Therefore, a group of conductive particles with the same shape and the same number of electrodes (two) of the μLED can be considered as a second group 4. In the case of this second group 4 being arranged side by side, it can be seen that the conductive particles are densely packed in the first group 3 at a distance L3, and the second group 4 is separated by a distance L2, with the second group 4 separated by a distance L1. Therefore, the conductive particles (filler) arranged on the film are not uniformly present on one side, but are present on one side in groups with regularity composed of different distances. Therefore, L1 is defined as the "closest distance between the second groups" as described above, but in practice, it is preferable to have (mixed) a distance between the second groups that is larger than L1.

[0043] Considering that when multiple μLEDs 20 arranged on wafer 22 are connected to the substrate through a filler film 1 by heating and pressurizing, the resin flow of the insulating resin layer 10 of the filler film 1 should not easily affect the arrangement of conductive particles 2 in the second group 4, L1 and L2 are appropriately determined based on the shape, arrangement spacing, and electrode distance of the μLEDs 20. Furthermore, L1 and L2 are also determined based on the design of the μLEDs and sub-millimeter LEDs; for example, to adjust the display resolution and performance as a light source, a lower limit of 10μm or more is sufficient, while an upper limit can be set to 3000μm or less, or 1000μm or less, or 500μm or less.

[0044] Ideally, the area of ​​the outline shape of the second group 4, which is connected to the conductive particles 2 on the outer periphery of the conductive particles 2 constituting the second group 4, satisfies the following ratio relative to the outer shape of the corresponding μLED 20. That is, if the lower limit of the ratio of the area of ​​the outline shape of the second group 4 to the area of ​​the outer shape of the μLED 20 is reduced, the conductive particles 2 can easily fall into the outer shape of the μLED 20. In order to facilitate the capture of conductive particles by electrodes, 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. On the other hand, if the upper limit is increased, concerns about insufficient conductive particles captured by the electrodes can be avoided, but transparency and aesthetics may be compromised. Therefore, this ratio is preferably 1.5 times or less, more preferably 1.3 times or less, and even more preferably 1.2 times or less.

[0045] Furthermore, considering that the alignment of the first group 3 of the filler arrangement film 1, the electrode 21 of the μLED 20, and the electrode of the substrate is allowed to have a deviation of approximately ±10%, the area of ​​the outline shape of the first group 3, which is connected to the conductive particles on the outer periphery of the conductive particles 2 constituting the first group 3, can be 0.5 to 1.8 times the area of ​​the corresponding electrode 21 of the μLED 20, preferably 0.8 to 1.2 times. Within this range, the number of conductive particles will not be excessive or insufficient, thus balancing capture and short circuit, and a good capture state is easily obtained and confirmed.

[0046] In this invention, a first group 3 may exist in a second group 4 in a number corresponding to the number of connecting parts of a first article, and in particular, there may be three or fewer. In this embodiment, there are two first groups 3.

[0047] Regarding the relationship between the closest distance L3 between conductive particles in the first group 3 and the average particle size D of conductive particles 2, the ratio L3 / D is preferably 0.3 or more with respect to the lower limit, more preferably 0.5 or more with respect to the upper limit, and preferably 4 or less with respect to the upper limit, more preferably 3 or less.

[0048] The arrangement of conductive particles 2 in the first group 3 can be random or regular. From the perspective of improving the capture efficiency of conductive particles in each electrode 21, a planar grid pattern with one or more arrangement axes is preferred. These arrangement axes are formed by arranging conductive particles at a predetermined interval in a predetermined direction. Examples include rhomboid grids, hexagonal grids, square grids, rectangular grids, and parallel grids. Furthermore, regions with different planar grid patterns may exist.

[0049] On the other hand, in this invention, the average number density of fillers in the entire surface of the filler-arranged membrane 1 and the average number density of fillers in the first group 3 are designed according to the object using the filler-arranged membrane. For example, regarding the lower limit of the average number density in the entire surface, in the case of a sparse state, it is preferably 500 fillers / mm. 2 In the above, under the preferred dense condition, the density is preferably 20,000 particles / mm. 2 The above is preferred, with 40,000 pieces / mm being more ideal. 2 above.

[0050] The lower limit of the average number density of fillers in group 3 is preferably 50,000 per mm. 2 The above, more preferably 500,000 pieces / mm 2 In addition, regarding the upper limit of the average number density, it is preferably 1,500,000 per mm. 2 The following is preferred: 1,000,000 pieces / mm 2 the following.

[0051] The average number density of fillers between the second group 4 is preferably 1000 per mm. 2 Below, it is preferred that it be substantially zero.

[0052] It should be noted that, depending on the design of the object, the range may sometimes exceed the aforementioned lower and upper limits.

[0053] The average filler area occupancy rate across the entire surface of the filler-arranged membrane 1 and the average filler area occupancy rate in the first group 3 are considered in the same way as the average number density. For example, if a small and dense particle size is preferred depending on the object using the filler-arranged membrane 1, the average filler area occupancy rate in the first group 3 can be set to 5% or more, 8% or more, or 25% or more, and can also be set to 85% or less or 50% or less. Here, the filler area occupancy rate in this embodiment refers to the conductive particle area occupancy rate, which is the number density (particles / mm²) of conductive particles viewed from above through the filler-arranged membrane 1. 2 ) × Average top-view area of ​​a conductive particle (mm²) 2 The number density is calculated by multiplying ( / piece) by 100. In the case of fabricating the filler-arranged membrane into very small monoliths, this refers to the number density measured in the state before monolithization.

[0054] It should be noted that the number density of conductive particles is determined using a metal microscope. Alternatively, it can be determined by measuring and observing images using image analysis software (e.g., WinROOF (Mitani Shoji Co., Ltd.), A-Image (registered trademark) (Asahi Kasei Engineering Co., Ltd.). Regarding the number of conductive particles, the number observed on the filler-coated film is measured.

[0055] (filler)

[0056] 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. Regarding the upper limit of the particle size, for example, from the viewpoint of the capture efficiency of conductive particles in the connecting structure, it is preferably 50 μm or less, and more preferably 20 μm or less. Depending on the size of the electrode, it is sometimes required that the particle size of the conductive particles be less than 3 μm, preferably less than 2.5 μm, and more preferably less than 2 μm. When the particle size is less than 1 μm, it can also be processed in the form of an aggregate with a particle size of 1 μm or more.

[0057] The average particle size can be set to a value measured using an image-based particle size analyzer (for example, FPIA-3000: manufactured by Malvern Panalytical). In this case, the number of particles is 1000 or more, preferably 2000 or more.

[0058] Furthermore, the type of conductive particles can be appropriately selected from those used in known anisotropic conductive films. 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 microparticles attached to their surface. Two or more types can also be used together. Among these, metal-coated resin particles are preferred from the perspective of stable conductivity because the resin particles easily maintain contact with the terminals after connection due to their rebound. Furthermore, the surface of the conductive particles can be insulated using known techniques without impairing conductivity characteristics.

[0059] It should be noted that, in the filler arrangement film of the present invention, the filler is appropriately selected from inorganic fillers (metal particles, metal oxide particles, metal nitride particles, etc.), organic fillers (resin particles, rubber particles, etc.), and fillers in a mixture of organic and inorganic materials (e.g., particles with a core formed of resin material and a surface metal-plated (metal-coated resin particles); particles with insulating microparticles attached to the surface of conductive particles; particles with insulating treatment on the surface of conductive particles, etc.) based on the performance required for the application, such as hardness and optical properties.

[0060] For example, when the filler-arranged film is used as a conductive film or anisotropic conductive film, conductive particles are contained as fillers. Depending on the application of the filler-arranged film, fillers other than conductive particles may also be used.

[0061] When filler films are used for color adjustment in micro-optical components such as μLEDs and for black matrices in color displays, known pigments, dyes, and light-scattering particles can be used as fillers. When the filler film is used for optical or matting applications, silica, titanium dioxide, styrene, acrylic, melamine, and various titanates can be used as fillers. In capacitor films, titanium dioxide, 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. Adhesive films can contain polymer-based rubber particles and silicone rubber particles.

[0062] (Cross-sectional structure of the filler-arranged membrane)

[0063] Figure 3 yes Figure 1 The diagram shows a cross-sectional view along line A-A of the filler-arranged membrane 1. In the region of the first group 3 of the filler-arranged membrane 1 in this embodiment, conductive particles 2 are arranged in the insulating resin layer 10.

[0064] The insulating resin layer 10 can be composed of a single insulating resin layer or a laminate of multiple resin layers. The positions of the ends of the conductive particles 2 are preferably substantially aligned with one side of the layer. "Substantially aligned" means, for example, including an error of approximately ±10% of the particle size. When the insulating resin layer is formed as a laminate of multiple resin layers, for example, it can be as follows: Figure 3 The diagram shows a high-viscosity adhesive resin layer 11 that retains the conductive particles 2, and an adhesive layer 12 with a lower viscosity than the high-viscosity adhesive resin layer 11. The resins constituting the high-viscosity adhesive resin layer 11 and the adhesive layer 12 can, for example, be the same as the adhesive and adhesive layers constituting the insulating resin layer described in Patent Document 3. Alternatively, different fillers can be incorporated into different layers for lamination.

[0065] Rubber components, inorganic fillers, silane coupling agents, diluent monomers, fillers, softeners, colorants, flame retardants, thixotropic agents, etc., can be added to the insulating resin layer 10 as needed.

[0066] Rubber components can also be incorporated to prevent warping and strain in the connecting structures. There are no particular limitations on the rubber component as long as it is an elastomer with high cushioning (shock absorption). Specific examples include: acrylic rubber, silicone rubber, butadiene rubber, polyurethane resin (polyurethane-based elastomers), etc.

[0067] Regarding the thickness of the insulating resin layer 10, when the μLED20 and the substrate are joined by heating and pressurizing with the filler arrangement film 1 in between, in order to prevent useless resin flow in the insulating resin layer, and further, to prevent resin outflow and agglomeration when the filler arrangement film 1 is made into a roll, the lower limit of the layer thickness is 0.6 times or more the average particle size of the conductive particles 2, preferably 0.9 times or more, more preferably 1 times or more, and the upper limit is 3 times or less, preferably 2 times or less, 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 size of the conductive particles 2, the conductive particles 2 will be exposed from the insulating resin layer 10, thus making temporary adhesion of the filler arrangement film 1 to the μLED20 or the substrate difficult when using the filler arrangement film 1 to join the μLED20 to the substrate. On the other hand, if the thickness of the insulating resin layer 10 exceeds three times the average particle size of the conductive particles 2, excessive resin flow will occur when the μLED20 is connected to the substrate. Due to the resin flow, the conductive particles 2 will flow, and the capture capacity of the conductive particles 2 in the electrode will decrease.

[0068] Furthermore, for manufacturing reasons based on particle arrangement, 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. Regarding the upper limit, if the layer thickness becomes too large, deviations during connection are likely to occur; therefore, it is preferably 32 μm or less, more preferably 20 μm or less, and even more preferably 8 μm or less.

[0069] Furthermore, in the case of this invention, the μLED itself is small, and its size is closer to that of the conductive particles than before. There is a concern that the μLED is prone to deviation, but this deviation is preferably avoided as a connection structure. For this reason, the thickness of the insulating resin layer 10 is also required to fall within the aforementioned range.

[0070] (Manufacturing method of filler-arranged membrane)

[0071] Regarding the filler arrangement film 1, the conductive particles can be configured in a specific way as described above, and otherwise manufactured in the same manner as known anisotropic conductive films. For example, similar to the manufacturing method of the anisotropic conductive film described in Patent Document 3, firstly, a mold with recesses corresponding to the arrangement pattern of the conductive particles is prepared, conductive particles 2 are filled into the mold, a high-viscosity adhesive resin layer 11 formed on a release film is attached thereon, the conductive particles 2 are pressed into the high-viscosity adhesive resin layer 11 for transfer attachment, and an adhesive layer 12 is laminated on its transfer attachment surface.

[0072] (Connection method using filler-arranged membranes)

[0073] Regarding the method of connecting the electrodes of μLED20 to the electrodes of the substrate using a filler arrangement film 1 in a state where multiple μLED20s are regularly arranged on the wafer 22, firstly, the filler arrangement film 1 is aligned and adhered to the electrodes of the substrate, then the filler arrangement film 1 is aligned and adhered to the μLED20s arranged on the wafer 22, and heat and pressure are applied to connect the electrodes of the μLED20 to the electrodes of the substrate. In this case, the connection can be performed by heat and pressure in a two-stage manner as described in Patent Document 3. Furthermore, if the conductive particles are solder particles or the like, the connection can be achieved by reflow soldering.

[0074] During heating and pressurization, the insulating resin layer 10 of the filler-arranged film 1 flows and fills the gap between the μLED20 and the substrate, then cures, thereby bonding the μLED20 and the substrate. The resin flowability is high between the second group 4 without conductive particles, but low within the second group 4 compared to the flowability between the groups. Therefore, the conductive particles 2 of the first group 3, which are arranged within the second group 4 corresponding to the electrodes of the μLED20, are less affected by the resin flow between the groups 4, and the electrodes 21 of each μLED20 can reliably capture the conductive particles 2.

[0075] Furthermore, within the second group 4, the first group 3 is configured to be spaced apart from each other by a distance L2, corresponding to the configuration of the electrode 21, thus suppressing short circuits between the electrodes 21 within a μLED 20.

[0076] Furthermore, in the filler arrangement film 1, the conductive particles 2 are not present between the second group 4. Therefore, after being connected to the substrate, the light emitted by the μLED 20 will not be blocked by the conductive particles 2. Thus, compared with the case where the filler arrangement film in which the conductive particles are uniformly present on the entire film surface is used, the luminous efficiency of the light-emitting device with the μLED is improved.

[0077] It should be noted that the filler-arranged membrane can also be made into a monolithic shape. The size of the monolithic shape can be designed according to the object, for example, it can be set to be 5μm or more and 150μm or less on one side. In this way, it is expected that it can also be used for applications such as adjusting color and light, as described later. That is, a first article and a second article can be connected by making a monolithic membrane, or the monolithic membrane can be placed only on the electrode. Monolithization can be formed using mechanical methods, chemical methods, lasers, etc., to create slits. It should be noted that the slits do not need to penetrate into the substrate, or they can be half-cuts.

[0078] The temporary adhesion of the filler arrangement film, film transfer, and mounting of μLEDs onto the substrate can be achieved using known methods such as stamp materials and laser methods (laser peeling), or methods that utilize these methods (e.g., methods described in Japanese Patent Application Publication No. 9-124020, Japanese Patent Application Publication No. 2011-76808, Japanese Patent No. 6636017, Japanese Patent No. 6187665, etc.). There are no particular limitations on the method as long as it can achieve the inventive effect.

[0079] (Connection struct)

[0080] Regarding the connection structure between the μLED20 and the substrate formed by connecting the filler arrangement film 1 in the example using the method described above, the filler 2 in the first group 3 constitutes the connection site between the electrode 21 of the μLED20 and the electrode of the substrate. The example is described using a μLED as an example. In the present invention, the connection structure can also be a sub-millimeter LED.

[0081] As described above, to prevent the resin flow during connection from affecting the arrangement of conductive particles 2 within the second group 4, similar to before connection, after connection, in the planar arrangement of the filler, the second group, composed of multiple units of the first group, also exists corresponding to the mounting position of the μLED, and the second group is also arranged corresponding to the arrangement of the μLED. Moreover, regardless of whether a connection point is formed, when all conductive particles are observed, the closest distance between the connected second groups is set as L1', the closest distance between the connected first groups is set as L2', and the closest distance between conductive particles is set as L3', maintaining the relationship L1' > L2' > L3'.

[0082] Compared to the connection structure described above, which uses a filler film with conductive particles uniformly distributed across the entire film surface to connect μLEDs to the substrate, this connection structure offers improved luminous efficiency. Furthermore, the conductive particles in each electrode exhibit high trapping ability, reducing the incidence of short circuits.

[0083] The above describes the connection method using the filler arrangement film of the present invention and the connection structure obtained therefrom, based on the case where the first item is set as a μLED, the second item is set as a substrate with wiring circuit formed on the μLED, and the filler of the filler arrangement film is set as conductive particles. However, the present invention is not limited thereto.

[0084] For example, the first item can be a light scattering film, a black matrix layer, etc., and the second item can be a transparent substrate (a substrate equipped with μLEDs), etc. The filler can be silicon dioxide, black-colored particles, etc., thereby adjusting the color tone of the connection structure between the first item and the second item.

[0085] Example

[0086] The present invention will now be described in detail based on embodiments.

[0087] Examples 1-3, Comparative Examples 1 and 2

[0088] (Fabrication of anisotropic conductive films)

[0089] The resins were mixed according to the resin composition in Table 1, coated onto the release film, and dried (60°C, 3 minutes) to obtain the adhesive film.

[0090] [Table 1]

[0091]

[0092] On the other hand, a mold with recesses filled with conductive particles was made in the same manner as described in Japanese Patent No. 6187665, using conductive particles (resin particles with an average particle size of 2.2 μm or 3.2 μm and plated with 0.2 μm Ni, Sekisui Chemicals Co., Ltd.) in the configuration shown in Table 2. The recesses were filled with conductive particles, the adhesive film in Table 1 was covered, and the conductive particles were pressed into the adhesive film to produce an anisotropic conductive film.

[0093] [Table 2]

[0094]

[0095] (Evaluation of anisotropic conductive films)

[0096] The particle trapping properties, insulation properties, and visible light transmittance of the anisotropic conductive films used in Examples 1-3 and Comparative Examples 1 and 2 were evaluated as described below. The results are shown in Table 2.

[0097] (i) Particle trapping

[0098] 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 simulating a μLED was heat-pressed onto it (reaching a temperature of 150°C, applying a pressure of 30 MPa for 10 seconds) to obtain a mounting body. The evaluation IC chip has the following electrode layout: 10 μm × 10 μm bumps are arranged in pairs (with a 7 μm gap between the bumps) on approximately one side within a 1.5 cm × 1.5 cm area with a 30 μm spacing.

[0099] The number of conductive particles captured by each of the 100 bumps on the mount was measured by observing them. The following criteria were used to evaluate the lowest number of these 100 bumps.

[0100] A: More than 5.

[0101] B: 3 to 4.

[0102] C: 1 to 2.

[0103] D: 0.

[0104] (ii) Insulation

[0105] The conduction resistance was measured between the 100 bumps of the aforementioned mounting body at intervals. 7 A value below Ω is considered a short circuit. The following criteria were used to evaluate the number of short circuits.

[0106] A: No short circuit.

[0107] B: One circuit is short-circuited.

[0108] C: Two short circuits.

[0109] D: Three or more short circuits.

[0110] (iii) Visible light transmittance

[0111] The visible light transmittance (400 nm to 700 nm) of the anisotropic conductive films of Examples 1-3 and Comparative Examples 1 and 2 was measured, and evaluated according to the following criteria based on their average transmittance (measurement area 10 mm × 10 mm). In this case, as anisotropic conductive films, the films were placed at 200°C for 1 minute while attached to a substrate, and the cured state of the films was measured. This allows observation of how the resin flowing out of the connection structure affects the film.

[0112] A: More than 50%.

[0113] B: More than 35%.

[0114] C: More than 20%.

[0115] D: Less than 20%.

[0116] As shown in Table 2, when using an anisotropic conductive film in an embodiment that causes conductive particles to be biased toward bumps present in μ-chips or μ-LEDs, particle trapping, insulation, and visible light transmittance all achieve excellent ratings of B or higher.

[0117] Explanation of reference numerals in the attached figures

[0118] 1: Filler arrangement film; 2: Filler, conductive particles; 3: First group; 4: Second group; 10: Insulating resin layer; 11: High viscosity adhesive resin layer; 12: Adhesive layer; 20: First item, μLED; 21: Electrode (connection part); 22: Wafer; L1: Closest distance between the second group; L2: Closest distance between the first group; L3: Closest distance between fillers in the first group; Ls: Electrode distance between μLEDs.

Claims

1. A filler arrangement membrane, which is formed by arranging filler in an insulating resin layer, used to connect the connecting portions of a plurality of first articles to the connecting portions of second articles. In the insulating resin layer, a first group is formed by multiple fillers disposed at positions corresponding to the various connection portions of the first article. A second group is formed by assembling multiple first groups in accordance with the shape of the first article. The second group is arranged regularly and in accordance with the arrangement of multiple first articles. The closest distance between the second group is greater than the closest distance between the first group. The closest distance between the first groups is greater than the closest distance between the packing materials within the first group.

2. The filler arrangement membrane according to claim 1, wherein, A second group is formed by three or more of the first groups.

3. The filler arrangement membrane according to claim 1 or 2, wherein, The average number density of fillers in the entire membrane is 20,000 fillers / mm². 2 Above and 1,500,000 pieces / mm 2 the following.

4. The filler arrangement membrane according to claim 1 or 2, wherein, The average filler coverage area of ​​the entire membrane is above 25% and below 50%.

5. The filler arrangement membrane according to claim 1 or 2, wherein, The ratio of the closest distance L3 between packings to the average particle size D of the packings, L3 / D, is greater than 0.3 and less than 4.

6. The filler arrangement membrane according to claim 1 or 2, wherein, The thickness of the insulating resin layer is more than 0.6 times and less than 3 times the average particle size of the filler.

7. The filler arrangement membrane according to claim 1 or 2, wherein, The filler is composed of conductive particles.

8. A method for manufacturing a connecting structure, wherein, The method for manufacturing the connecting structure involves heating or pressurizing the connecting portions of each of the first articles and the connecting portions of the second articles, separated by a filler film formed by fillers arranged in an insulating resin layer, while a plurality of first articles are arranged on a second article, thereby connecting the connecting portions of the first articles and the second articles. The following filler arrangement membrane is used as the filler arrangement membrane. In the insulating resin layer, a first group is formed by multiple fillers disposed at positions corresponding to the various connection portions of the first article. Multiple units of the first group are assembled to form a second group, corresponding to the shape of the first article. The second group is arranged regularly and in a manner corresponding to the arrangement of the first article. The closest distance between the second group is greater than the closest distance between the first group. The closest distance between the first groups is greater than the closest distance between the packing materials within the first group.

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

10. A connecting structure having a connecting portion wherein, in a state where a plurality of first articles are arranged on a second article, the connecting portion of each of the first articles is connected to the connecting portion of the second article through a filler. A first group is formed by multiple fillers disposed at positions corresponding to the various connecting parts of the first article, and the fillers within the first group constitute the connecting parts. A second group is formed by combining multiple items from the first group at locations corresponding to the loading positions of the first item. The second group corresponds to and is arranged regularly with respect to the first group of items. The closest distance between the second group is greater than the closest distance between the first group. The closest distance between the first groups is greater than the closest distance between the packing materials within the first group.

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

Images