CN117063351A

CN117063351A - Filler alignment film

Info

Publication number: CN117063351A
Application number: CN202280022620.8A
Authority: CN
Inventors: 野田大树; 冢尾怜司
Original assignee: Dexerials Corp
Current assignee: Dexerials Corp
Priority date: 2021-03-26
Filing date: 2022-03-24
Publication date: 2023-11-14

Abstract

The invention provides a filler alignment film, wherein when a connecting part of a tiny first article such as an electrode of a mu LED is connected with a connecting part of a second article such as an electrode of a large-screen television substrate through a filler by using the filler alignment film formed by arranging conductive particles and the like on an insulating resin layer, even if the alignment deviation of the first article and the second article is about +/-10%, the actual capturing number of the filler in each connecting part can be reliably more than 1. In the filler alignment film (1), the fillers (2) are aligned in the insulating resin layer (10), and a plurality of first groups (3) formed by a plurality of fillers (2) in the insulating resin layer (10) are gathered to form second groups (4), and the second groups (4) are regularly aligned. The closest distance (L1) between the second clusters (4) is greater than the closest distance (L2) between the first clusters, and the closest distance (L2) between the first clusters is greater than the closest distance (L3) between the fillers in the first clusters.

Description

Filler alignment film

Technical Field

The present invention relates to a filler alignment 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 alignment film, and a connection structure obtained by the method. Examples of the minute first article include minute light emitting elements such as a sub-millimeter LED (Mini LED) and a micro LED.

Background

A LED display in which a LED as a micro light emitting element is arranged on a substrate can omit a backlight required for a liquid crystal display, and thus can be made thin, and is expected as a display or a light source that can realize a wide color gamut, high definition, and power saving.

As a method for manufacturing a display in which a LED array is arranged, patent document 1 describes that a red, blue, and green LED array formed on a carrier substrate is picked up by a transfer head, placed on a transfer target substrate such as a display substrate, the LED array is bonded to the transfer target substrate by fusion of a solder layer, and then a contact line is formed thereon by ITO or the like.

Patent document 2 describes the following method: the LED array is formed on a wafer, and the LED array is connected to the substrate by using an anisotropic conductive film in which conductive particles are dispersed in an adhesive component using a hydrogenated epoxy compound or the like, and the wafer is peeled (lift off). According to the method using an anisotropic conductive film described in patent document 2, a display using a μled can be obtained easily.

Patent document 3 describes a two-stage connection method: when an IC chip and an FPC are connected by using an anisotropic conductive film having a conductive particle alignment layer with an area occupancy rate of conductive particles of 35% or less in a plan view, a pulse heater type bonding machine is used to improve the capturing efficiency of the conductive particles, and in a first stage, the IC chip and the FPC are pressed into an insulating resin layer of the anisotropic conductive film to temporarily fix electrodes close to the conductive particle alignment layer, and in a second stage, main compression bonding is performed.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2015-500562

Patent document 2: japanese patent laid-open No. 2017-157724

Patent document 3: japanese patent laid-open publication No. 2019-216097

Disclosure of Invention

Problems to be solved by the invention

When the size of the LED electrode is reduced in order to achieve high definition of the display, and the size of the LED electrode is also reduced, it is difficult to reliably capture the conductive particles by the electrode of each LED when an anisotropic conductive film in which only the conductive particles are mixed with an insulating material is used.

In view of this, it is considered to use conductive particles having a small particle diameter to increase the number density of conductive particles in the conductive film or the anisotropic conductive film.

However, if the particle size of the conductive particles is reduced, the conductive particles tend to move due to the flow of the resin material constituting the anisotropic conductive film when the LED and the substrate are heated and pressurized when the anisotropic conductive film is connected therebetween, and there is a risk that the inter-electrode conductive particles are connected to each other to cause a short circuit in a highly-sophisticated display because the inter-electrode space is extremely narrow.

In order to suppress the movement of conductive particles during connection, a pulse heater type bonding machine described in patent document 3 is also considered, but even in this method, since the area that can be connected in one press bonding is limited, a large-area display such as a large-screen television cannot be press bonded at one time using an anisotropic conductive film.

Accordingly, an object of the present invention is to provide a filler alignment film in which a connection portion of a fine first article such as an electrode of a μled is connected to a connection portion of a second article such as an electrode of a large-screen television substrate via a filler, wherein even if the alignment between the first article and the second article is about ±10%, the actual number of captured fillers in each connection portion can be reliably made to be 1 or more; and a method for connecting a minute first article and a minute second article using the filler alignment film described above, and a connection structure obtained by the method.

Solution for solving the problem

The present inventors have made a finding that the present invention has been completed by connecting a connection portion of a tiny first article such as an electrode of a LED to a connection portion of a second article such as an electrode of a large-screen television substrate via a filler using a filler alignment film in which a filler such as conductive particles is aligned in an insulating resin layer, in which case the filler in the filler alignment film forms a first group at a position corresponding to the connection portion of the first article, the first group is plural to form a second group corresponding to the outer shape of the first article, unnecessary fillers that do not participate in connection can be reduced as much as possible when the second group is aligned corresponding to the alignment of the first article, and the resin flows between the second groups at the time of connection, thereby hardly affecting the inside of the second group, and in which case the first article is a light emitting element such as a LED, the filler does not hinder light from the light emitting element, and the light emitting efficiency of the light emitting device to which the light emitting element is mounted is improved.

That is, the present invention provides a filler alignment film in which fillers are aligned in an insulating resin layer, wherein a plurality of first groups of a plurality of fillers are formed in the insulating resin layer to form second groups, the second groups are regularly aligned, 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 in the first groups.

The present invention also provides a method for producing a connection structure, wherein the connection structure is produced by heating or pressurizing a filler alignment film in which a filler is aligned in an insulating resin layer between a connection portion of each first article and a connection portion of a second article in a state where a plurality of first articles are aligned in the second article, wherein the filler alignment film is used, and wherein a plurality of first groups of the plurality of fillers are gathered together in correspondence with the outer shape of the first articles at positions corresponding to the connection portion of the first articles to form a second group, the second groups are aligned in correspondence with the alignment 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 in the first groups.

Further, the present invention provides a connection structure having the following connection portions: in a state where a plurality of first articles are arranged on a second article, a connection portion is formed by a plurality of fillers in a first group, the plurality of first groups are arranged in correspondence with mounting positions of the first articles, the second groups are arranged in correspondence with the arrangement of the first articles, a closest distance between the second groups is larger than a closest distance between the first groups, and a closest distance between the first groups is larger than a closest distance between the fillers in the first groups.

Effects of the invention

When the filler alignment film of the present invention is used, the filler alignment film in which the filler such as conductive particles is arranged through the insulating resin layer is heated or pressurized, whereby the connection portion of the micro first article such as the electrode of the LED is connected to the connection portion of the second article such as the electrode of the large-screen television substrate, and in this case, one or more fillers can be reliably trapped between the connection portion of the first article and the connection portion of the second article, and the risk of filler connection between the connection portions of adjacent first articles or between the connection portions of the second articles is low. This reduces the risk of short-circuiting when electronic components such as a μled are connected to a substrate.

In addition, in the case where the first article is a light-emitting element such as a μled, the second group corresponding to the outer shape of the light-emitting element is arranged in correspondence with the arrangement of the light-emitting elements, and therefore, the emission of light from the light-emitting element is not hindered by the second group. This improves the light-emitting efficiency of the light-emitting device mounted with the light-emitting element.

Drawings

Fig. 1 is a configuration diagram of a filler in a filler alignment film of the embodiment.

Fig. 2 is a corresponding diagram of the arrangement of the filler in the filler aligned film of the embodiment and the connection portion of the article connected by the filler aligned film.

FIG. 3 is a cross-sectional view A-A of the packing arrangement film of the embodiment of FIG. 1.

Detailed Description

The present invention will be described in detail below with reference to the drawings. In the drawings, the same reference numerals denote the same or equivalent components.

(Filler configuration)

Fig. 1 is a configuration diagram of a filler in a filler alignment film 1 according to an embodiment of the present invention. The filler alignment film 1 is a film in which conductive particles are aligned as a filler 2 in an insulating resin layer 10. Hereinafter, the filler alignment film 1 of the example will be described mainly as an anisotropic conductive film, but the filler alignment film of the present invention can also be used as a conductive film for electrically connecting articles to each other.

In the filler alignment film of the present invention, the first article and the second article are connected to each other by heating or pressurizing the first article and the second article through the filler alignment film in a state where the plurality of first articles are aligned on the second article, and in this connected state, the filler is sandwiched between the connection portion of each first article and the connection portion of the second article, and the facing surfaces of the first article and the second article are bonded to each other by the insulating resin layer.

The filler alignment film 1 of the present embodiment can be used as an anisotropic conductive film for anisotropically conductively connecting a first article and a second article, in the case where the first article is a μled, the electrode thereof is a connection portion of the first article, the second article is a substrate on which a wiring circuit for the μled is formed, and the electrode thereof is a connection portion of the second article. The filler alignment film 1 can also be used as a conductive film.

As shown in fig. 2, each of the LED pairs 20 connected using the filler alignment film 1 of the present embodiment has two electrodes 21, and is arranged regularly in a lattice shape on a wafer 22.

Regarding the external shape and size of the LED20, for example, in the case of a rectangular external shape, the long side thereof is 200 μm or less, or less than 150 μm, or less than 50 μm, or less than 20 μm. More specifically, examples thereof include rectangles of 10 μm×20 μm, 7 μm×14 μm, and 5 μm×5 μm. The outline of the LED20 is not limited to a rectangle, and may be, for example, a diamond shape.

The external shape and size of the electrodes 21 are not particularly limited, and in the case of a small LED, a rectangle having a long side of 5 μm to 50 μm and a short side of 3 μm to 40 μm may be used, and the interval Ls between the electrodes 21 in one LED20 may be appropriately selected according to the method of use. The lower limit is preferably 3 μm or more, more preferably 5 μm or more, from the viewpoint of convenience of the mounting step. The upper limit is not particularly limited. In the case of an element larger than a μled or a sub-millimeter LED and used alone, the element may be 3000 μm or less. In the case of display application, the thickness may be 1000 μm or less, 500 μm or less, 150 μm or less, or 20 μm or less.

In the filler alignment film 1, a plurality of conductive particles (fillers) 2 arranged at positions corresponding to the respective electrodes (connection portions) 21 of the μled (first article) 20 form a first group 3, and the plurality of first groups 3 are assembled in correspondence with the outer shape of the μled20, thereby forming a second group 4. The second group 4 is regularly arranged corresponding to the arrangement of the mu LEDs 20.

Here, the arrangement of the first group 3 at a position corresponding to the electrode 21 of the μled20 means that, when the plurality of μleds 20 in a predetermined arrangement state are aligned with the filler arrangement film 1, the electrode 21 of each μled20 overlaps the first group 3 in a plan view, and the interval Ls between the electrodes 21 of each μled20 overlaps the interval L2 between the first group 3, and preferably means that the electrode 21 is located in the first group 3 or one or more of the conductive particles 2 constituting the first group 3 overlaps the electrode 21.

The arrangement of the second group 4 in correspondence with the arrangement of the μleds 20 means that each μled20 overlaps the second group 4 in a plan view by the alignment described above, and the interval between each μled overlaps the interval L1 between the second group 4, and preferably means that the sum of the areas of the conductive particles 2 that deviate from the outline of the μled20 among the conductive particles 2 that constitute the second group 4 is within 50% of the outline area of the μled20, and more preferably means that all the conductive particles 2 that constitute the second group 4 are located within the outline of each μled 20.

The arrangement of the second group 4 in correspondence with the arrangement of the μleds 20 means that the arrangement direction and arrangement pitch of the second group 4 are equal to the arrangement direction and arrangement pitch of the μleds 20.

In order to reduce the problem of appearance after the fine components are mounted on the filler alignment film 1 between the second groups 4, it is desirable that the conductive particles 2 are small, and particularly, in the case where the particle diameter of the conductive particles 2 is smaller than 3 μm, the aggregation or irregular conductive particles existing between the second groups 4 are small.

As described above, the first group 3 of conductive particles of the filler alignment film 1 corresponds to the electrode 21 of the μled20, and the second group 4 corresponds to the outer shape of the μled20, and 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 a second group closest to the second group) is 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 a first group closest to the first group) is L2, and the closest distance between the conductive particles 2 in the first group 3 is L3, in which case L1 > L2 > L3.

The first group 3 corresponds to the electrodes 21 of the μled20, and thus the same-appearance conductive particle group in which the number of electrodes (two) of the μled are juxtaposed can be regarded as one second group 4. In the case where the second group 4 is arranged in parallel, it can be considered that the conductive particles are separated by a distance L1 between the first group 3 in which the distance L3 is relatively dense and the second group 4 in which the conductive particles are separated by a distance L2. Therefore, the conductive particles (filler) arranged in the film are not uniformly present on one surface, but are present on one surface as a group composed of regularity of different distances. Therefore, L1 is a distance defined as "closest distance between the second groups" as described above, but it is practically preferable that there is (mixed presence of) a second inter-group distance having a distance larger than L1.

In terms of the resin flow of the insulating resin layer 10 of the filler alignment film 1 being less likely to affect the arrangement of the conductive particles 2 in the second group 4 when the plurality of μleds 20 aligned on the wafer 22 and the substrate are connected by heating and pressurizing the filler alignment film 1, L1 and L2 are appropriately determined in accordance with the outline, the alignment pitch, the inter-electrode distance, and the like of the μleds 20. The L1 and L2 are also determined according to the design of the LED and the sub-millimeter LED, and for example, in order to adjust the resolution on the display and the performance as a light source, the lower limit may be 10 μm or more, and the upper limit may be 3000 μm or less, 1000 μm or less, or 500 μm or less.

It is desirable that the area of the outline shape of the second group 4, which circumscribes the conductive particles 2 constituting the outer peripheral portion of the conductive particles 2 of the second group 4, satisfies the following ratio with respect to the outline shape of the corresponding LED 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 outline shape of the μled20 is made smaller, the conductive particles 2 easily fall within the outline shape of the μled 20. In order to facilitate capturing of the conductive particles by the electrode, the 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, the possibility of insufficient conductive particles being trapped by the electrode can be avoided, but transparency and appearance may be impaired, and therefore the ratio is preferably 1.5 times or less, more preferably 1.3 times or less, and still more preferably 1.2 times or less.

In addition, from the viewpoint that the alignment of the electrodes 21 of the first group 3 and the μled20 of the filler alignment film 1 and the electrodes of the substrate allows a deviation of about ±10%, the area of the outline shape of the first group 3 circumscribed by the conductive particles constituting the outer peripheral portion of the conductive particles 2 of the first group 3 may be 0.5 to 1.8 times, preferably 0.8 to 1.2 times the area of the electrodes 21 of the corresponding μled 20. If the number of conductive particles falls within this range, the number of conductive particles does not become excessive or insufficient, and therefore both trapping and short-circuiting can be achieved, and a good trapping state can be easily obtained and also easily confirmed.

In the present invention, the first group 3 may be present in one second group 4 in a number corresponding to the number of the connecting portions of one first article, and in particular, three or less, and in this embodiment, two first groups 3 may be present.

The ratio L3/D is preferably 0.3 or more, more preferably 0.5 or more, and preferably 4 or less, more preferably 3 or less, as the lower limit, in terms of the relationship between the closest distance L3 between the conductive particles in the first group 3 and the average particle diameter D of the conductive particles 2.

The arrangement of the conductive particles 2 in the first group 3 may be random or regular, and from the viewpoint of improving the trapping property of the conductive particles in each electrode 21, a planar lattice pattern having one or more arrangement axes in which the conductive particles are arranged at a predetermined pitch in a predetermined direction is preferable, and examples thereof include: diagonal lattices, hexagonal lattices, tetragonal lattices, rectangular lattices, parallel lattices, and the like. Further, there may be areas where the planar lattice patterns are different.

On the other hand, in the present invention, the average number density of the fillers in the entire surface of the filler aligned film 1 and the average number density of the fillers in the first group 3 are designed according to the object using the filler aligned film. For example, in the case of a sparse state, the lower limit of the average number density in the whole surface is preferably 500 pieces/mm ² In the above-mentioned case, in a compact state, 20000 pieces/mm are preferable ² The above is more preferably 40000 pieces/mm ² The above.

The lower limit on the average number density of the fillers in the first group 3 is preferably 50000 pieces/mm ² Above, more preferably 500000 pieces/mm ² The upper limit of the average number density is preferably 1500000 pieces/mm ² Hereinafter, more preferably 1000000 pieces/mm ² The following is given.

The average number density of the fillers of the intervals between the second group 4 is preferably1000 pieces/mm ² Hereinafter, it is more preferable that the value is substantially zero.

Depending on the design of the object, the above-described lower limit value and upper limit value may be exceeded.

The average filler area occupancy in the entire surface of the filler aligned film 1 and the average filler area occupancy in the first group 3 are both considered to be the same as the average number density. For example, when the object of the filler alignment film 1 is used in a state where the particle size is preferably small and dense, the average filler area occupancy in the first group 3 may be set to 5% or more, 8% or more, 25% or more, or 85% or less, 50% or less, as an example. Here, the filler area occupancy refers to the conductive particle area occupancy in this example, and the number density (number/mm) of conductive particles in plan view of the filler alignment film 1 ² ) X average of plan view area of one conductive particle (mm ² And/or x 100. In the case where the filler alignment film is made into a very small single sheet, it means the number density measured in the state before the single sheet.

The number density of the conductive particles may be obtained by observation with a metal microscope, or may be obtained by measuring an observation image with image analysis software (for example, winROOF (san francisco, ltd.) and a image monarch (registered trademark) (Asahi Kasei Engineering corporation). The number of conductive particles was measured as the number observed on the filler alignment film.

(Filler)

In this embodiment, the particle diameter of the conductive particles 2 as the filler is not particularly limited, and the lower limit of the particle diameter is preferably 1 μm or more. The upper limit of the particle diameter is preferably 50 μm or less, more preferably 20 μm or less, for example, from the viewpoint of capturing efficiency of the conductive particles in the connection structure. Depending on the size of the electrode, the particle size of the conductive particles is sometimes required to be less than 3. Mu.m, preferably less than 2.5. Mu.m, more preferably 2. Mu.m or less. When the particle diameter is smaller than 1. Mu.m, the treatment may be performed as an aggregate of 1 μm or more.

The average particle diameter may be measured by an image type particle size distribution meter (manufactured by FPIA-3000:Malvern Panalytical, inc., as an example). In this case, the number of particles is 1000 or more, preferably 2000 or more.

The type of the conductive particles may be appropriately selected from conductive particles used in a known anisotropic conductive film. For example, as the conductive particles, there may be mentioned: metal particles of nickel, cobalt, silver, copper, gold, palladium, etc.; alloy particles such as solder; metal-coated resin particles, metal-coated resin particles having insulating fine particles adhered to the surface, and the like. Two or more kinds may be used in combination. Among them, the metal-coated resin particles are preferable in that the resin particles rebound after connection to easily maintain contact with the terminals, and in that the conductive performance is stable. Further, the surface of the conductive particle may be subjected to an insulating treatment which does not interfere with the conductive property by a known technique.

In the filler alignment film of the present invention, the filler is appropriately selected according to the properties required for the application, such as hardness and optical properties, from among inorganic fillers (metal particles, metal oxide particles, metal nitride particles, etc.), organic fillers (resin particles, rubber particles, etc.), and fillers in which an organic material and an inorganic material are mixed (for example, particles in which the core is formed of a resin material and the surface is metal-plated (metal-coated resin particles), particles in which insulating fine particles are attached to the surface of conductive particles, particles in which the surface of conductive particles is insulating treated, etc.), according to the application of the filler alignment film.

For example, in the case of using a filler alignment film as a conductive film or an anisotropic conductive film, conductive particles are contained as a filler. Fillers other than conductive particles may be used depending on the purpose of the filler alignment film.

In the case of using the filler alignment film for adjustment of color development of micro optical elements such as a μled, black matrix in a color display, or the like, a known pigment, light scattering particle, or the like may be used as the filler. In the case where the use of the filler alignment film is an optical film, a matting film, a silica filler, a titanium oxide filler, a styrene filler, an acrylic filler, a melamine filler, various titanates, or the like can be used. As the film for a capacitor, titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, calcium titanate, strontium titanate, barium zirconate titanate, lead zirconate titanate, a mixture thereof, or the like can be used. The adhesive film may contain polymer rubber particles, silicone rubber particles, or the like.

(cross-sectional structure of filler alignment film)

Fig. 3 is a sectional view of A-A of the filler alignment film 1 shown in fig. 1. In the region of the first group 3 of the filler alignment film 1 of the present embodiment, the conductive particles 2 are aligned in the insulating resin layer 10.

The insulating resin layer 10 may be composed of a single insulating resin layer or a laminate of a plurality of resin layers. The positions of the end portions of the conductive particles 2 preferably substantially coincide with one side of the layer. The substantial uniformity is, for example, an error of about ±10% of the particle size. In the case of forming the insulating resin layer into a laminate of a plurality of resin layers, for example, as shown in fig. 3, the high-viscosity adhesive resin layer 11 holding the conductive particles 2 and the adhesive layer 12 having a lower viscosity than the high-viscosity adhesive resin layer 11 can be formed. The resin constituting the high-viscosity adhesive resin layer 11 and the adhesive layer 12 may be the same as the adhesive or the adhesive layer constituting the insulating resin layer described in patent document 3, for example. Different fillers may be disposed in different layers and laminated.

The insulating resin layer 10 may contain a rubber component, an inorganic filler, a silane coupling agent, a diluting monomer, a filler, a softener, a colorant, a flame retardant, a thixotropic agent, and the like, as necessary.

The rubber component may be blended to prevent warping and strain of the connection structure. The rubber component is not particularly limited as long as it is an elastomer having high cushioning properties (impact absorbability), and specific examples thereof include: acrylic rubber, silicone rubber, butadiene rubber, urethane resin (urethane elastomer), and the like.

When the LED20 and the substrate are connected to each other by heating and pressurizing the layer thickness of the insulating resin layer 10 through the filler alignment film 1, the lower limit of the layer thickness is 0.6 times or more, preferably 0.9 times or more, more preferably 1 time or more, and the upper limit is 3 times or less, preferably 2 times or less, more preferably 1.5 times or less, in view of preventing resin flow out and blocking in the case where the filler alignment film 1 is formed into a package, so that no unnecessary resin flow occurs in the insulating resin layer. If the layer thickness of the insulating resin layer 10 is smaller than 0.6 times the average particle diameter of the conductive particles 2, the conductive particles 2 are exposed from the insulating resin layer 10, and therefore when the LED20 is connected to the substrate using the filler alignment film 1, temporary adhesion of the filler alignment film 1 to the LED20 or the substrate becomes difficult. On the other hand, if the layer thickness of the insulating resin layer 10 exceeds 3 times the average particle diameter of the conductive particles 2, resin flow is excessively generated at the time of connection of the μled20 and the substrate, and the conductive particles 2 flow due to the resin flow, so that the trapping property of the conductive particles 2 in the electrode is reduced.

For reasons of production based on arrangement of particles, the thickness of the insulating resin layer 10 is preferably 2 μm or more, more preferably 3 μm or more. The upper limit is preferably 32 μm or less, more preferably 20 μm or less, and even more preferably 8 μm or less, because the thickness of the layer becomes too large, which tends to cause a variation in connection.

In the case of the present invention, the size of the LED itself is smaller, and the size of the LED is closer to the size of the conductive particles than before. The μ LED may be liable to be deviated, but it is preferable to avoid the deviation as the connection structure. For this reason, the thickness of the insulating resin layer 10 is also required to fall within the above-described range.

(method for producing filler alignment film)

The filler alignment film 1 can be produced in the same manner as a known anisotropic conductive film except that the conductive particles are arranged in a specific manner as described above. For example, as in the method for producing an anisotropic conductive film described in patent document 3, first, a mold in which recesses corresponding to the arrangement pattern of conductive particles are formed is prepared, conductive particles 2 are filled in the mold, a high-viscosity adhesive resin layer 11 formed on a release film is bonded thereto, the conductive particles 2 are pressed into the high-viscosity adhesive resin layer 11 and transferred and attached, and an adhesive layer 12 is laminated on the transferred and attached surface.

(connection method using filler alignment film)

In a method of connecting the electrodes of the LED20 to the electrodes of the substrate in a state where the LEDs 20 are regularly arranged on the wafer 22 using the filler alignment film 1, first, the filler alignment film 1 is aligned and bonded to the electrodes of the substrate, the filler alignment film 1 is aligned and bonded to the LEDs 20 arranged on the wafer 22, and the electrodes of the LED20 and the electrodes of the substrate are connected by heating and pressurizing. In this case, the connection can be performed by heating and pressurizing in two stages as described in patent document 3. In addition, in the case where the conductive particles are solder particles or the like, connection can be performed by reflow soldering.

When the insulating resin layer 10 of the filler alignment film 1 is heated and pressurized, the resin flows, fills the gap between the facing surfaces of the LED20 and the substrate, and is cured, thereby bonding the LED20 and the substrate, and at this time, the fluidity of the resin is high between the second groups 4 where the conductive particles are not arranged, and in the second groups 4, the fluidity of the resin is lower than between the second groups 4. Therefore, the conductive particles 2 of the first group 3 disposed in the second group 4 in correspondence with the electrodes of the μled20 are less susceptible to the resin flow between the second group 4, and the electrodes 21 of the respective μled20 can reliably capture the conductive particles 2.

In the second group 4, the first group 3 is arranged at a distance L2 from each other in correspondence with the arrangement of the electrodes 21, and thus occurrence of short-circuiting between the electrodes 21 in one LED20 can be suppressed.

In addition, in the filler alignment film 1, the conductive particles 2 are not present between the second group 4, and thus, after being connected to the substrate, the light emitted from the μled20 is not blocked by the conductive particles 2 therebetween, and thus, the light emitting efficiency of the light emitting device mounted with the μled is improved as compared with the case of using the filler alignment film in which the conductive particles are uniformly present over the entire surface of the film.

The filler alignment film may be formed in a monolithic shape. The size of the monolithic shape may be designed according to the object, and may be, for example, 5 μm or more and 150 μm or less on one side. Thus, it is expected that the present invention can be applied to applications for adjusting color and light, which will be described later. That is, the first article and the second article may be connected by a film formed in a single piece, or the film formed in a single piece may be disposed only on the electrode. Singulation may be formed using mechanical methods, chemical methods, laser, or the like to provide cuts, or the like. The notch may not extend into the substrate, and may be half-cut.

The method for temporarily attaching the filler alignment film, transferring the film, and mounting the LED on the substrate is not particularly limited as long as it can exhibit the effect of the invention, and known methods such as a stamp (stamp) material, a laser method (laser lift-off method), and methods using them (for example, methods described in japanese patent application laid-open No. 9-124020, japanese patent application laid-open No. 2011-76808, japanese patent 6636017, japanese patent No. 6187665, and the like) can be used.

(connection Structure)

In the connection structure of the LED20 and the substrate, which is formed by connecting the filler alignment film 1 of the embodiment by the above-described method, the filler 2 in the first group 3 forms the connection portion between the electrode 21 of the LED20 and the electrode of the substrate. In the embodiment described above, the μ LED is taken as an example, and in the present invention, the connection structure may be a sub-millimeter LED.

As described above, in order that the influence of the resin flow during connection is less likely to affect the arrangement of the conductive particles 2 in the second group 4, similarly to before connection, in the planar arrangement of the filler, the second group in which the first group is plural is also present in correspondence with the mounting position of the μled, and the second group is also arranged in correspondence with the arrangement of the μled. In addition, whether or not the connection portion is formed, when all the conductive particles are observed, the closest distance between the second groups after connection is L1', the closest distance between the first groups after connection is L2', and the closest distance between the conductive particles is L3', and in this case, the relationship of L1' > L2 '> L3' is maintained.

The connection structure has improved luminous efficiency compared with a connection structure in which the LED is connected to the substrate using a filler alignment film in which conductive particles are uniformly present over the entire surface of the film as described above. In addition, the trapping property of the conductive particles in each electrode is also high, and the occurrence ratio of short circuits is also reduced.

The connection method using the filler alignment film of the present invention and the connection structure obtained by the connection method have been described above with reference to the case where the first article is a μled, the second article is a substrate on which a wiring circuit of the μled is formed, and the filler of the filler alignment film is conductive particles, but the present invention is not limited to this.

For example, the color tone of the connection structure between the first article and the second article may be adjusted by using the first article as a light-scattering film, a black matrix layer, or the like, the second article as a transparent substrate (substrate on which the μled is mounted), or the like, and the filler as silica, black-colored particles, or the like.

Examples

Hereinafter, the present invention will be specifically described based on examples.

Examples 1 to 3 and comparative examples 1 and 2

(production of anisotropic conductive film)

The adhesive film was obtained by mixing the resins with the resin compositions shown in Table 1, applying the mixture to a release film, and drying the film (60 ℃ C., 3 minutes).

TABLE 1

On the other hand, in such a manner that conductive particles (resin particles having an average particle diameter of 2.2 μm or 3.2 μm and plated with 0.2 μm Ni, water chemical industry co.) were arranged as shown in table 2, a mold having recesses filled with conductive particles was produced in the same manner as the method described in japanese patent No. 6187665, conductive particles were filled in the recesses, the adhesive film of table 1 was covered, and the conductive particles were pressed into the adhesive film, thereby producing an anisotropic conductive film.

TABLE 2

(evaluation of Anisotropic conductive film)

Particle trapping property, insulation property, and visible light transmittance were evaluated as follows using the anisotropic conductive films of examples 1 to 3 and comparative examples 1 and 2. The results are shown in Table 2.

(i) Particle trapping property

The anisotropic conductive films of examples 1 to 3 and comparative examples 1 and 2 were attached to ITO/NdMo pattern glass, and an IC chip for evaluation simulating a. Mu. LED was thermally bonded thereto (to a temperature of 150 ℃ C., a pressure of 30MPa for 10 seconds) to obtain a mounted body. The IC chip for evaluation has the following electrode layout: the bumps 10 μm×10 μm are arranged in a group of two (inter-bump space 7 μm) at a pitch of 30 μm in a range of 1.5cm×1.5cm on substantially one surface.

The number of conductive particles captured by the bumps was measured by observing 100 bumps of the mounting body. Based on the lowest number of 100 bumps, the evaluation was performed according to the following criteria.

A: more than 5.

B:3 to 4.

C:1 to 2.

D: 0.

(ii) Insulation property

On-resistance was measured for 100 inter-bump spaces of the above-mentioned mounting body, and 10 ⁷ And omega or less is determined as a short circuit. Based on the number of short circuits, the evaluation was performed according to the following criteria.

A: no short circuit.

B: one is shorted.

C: two are shorted.

D: and more than three short circuits are caused.

(iii) Visible light transmittance

The visible light transmittance (400 nm to 700 nm) of the anisotropic conductive films of examples 1 to 3 and comparative examples 1 and 2 was measured, and the average transmittance (measurement area 10 mm. Times.10 mm) was evaluated based on the following criteria. In this case, as the anisotropic conductive film, the film in a cured state was measured by being left in a state of being attached to the substrate for 1 minute at 200 ℃. This makes it possible to observe how the resin flowing out of the connection structure affects.

A:50% or more.

B: more than 35 percent.

C:20% or more.

D: less than 20%.

As is clear from table 2, when the anisotropic conductive film of the example in which the conductive particles are biased to exist in the microchip or the bump of the LED was used, the particle trapping property, the insulation property, and the visible light transmittance were all excellent evaluations of B or more.

Description of the reference numerals

1: a filler alignment film; 2: filler and conductive particles; 3: a first group; 4: a second group; 10: an insulating resin layer; 11: a high-viscosity adhesive resin layer; 12: an adhesive layer; 20: a first article, a μled;21: an electrode (connection part); 22: a wafer; l1: the closest distance between the second clusters; l2: the closest distance between the first clusters; l3: the closest distance between the fillers in the first group; ls: inter-electrode distance of μled.

Claims

1. A filler alignment film comprising an insulating resin layer and a filler arranged on the insulating resin layer,

in the insulating resin layer, a plurality of first groups formed by a plurality of fillers are gathered to form a second group, the second groups are regularly arranged,

the closest distance between the second clusters is greater than the closest distance between the first clusters,

the closest distance between the first clusters is greater than the closest distance between the fillers in the first clusters.

2. The filler alignment film of claim 1, wherein,

one second group is formed by three or less first groups.

3. The filler alignment film according to claim 1 or 2, wherein,

the average number density of the filler in the whole surface of the filler alignment film was 20000 pieces/mm ² Above and 1500000/mm ² The following is given.

4. The filler alignment film according to any one of claim 1 to 3, wherein,

the average filler occupancy area ratio of the entire filler alignment film is 25% to 50%.

5. The filler alignment film according to any one of claims 1 to 4, wherein,

the ratio L3/D of the closest distance L3 between the fillers to the average particle diameter D of the fillers is 0.3 to 4.

6. The filler alignment film according to any one of claims 1 to 5, wherein,

the thickness of the insulating resin layer is 0.6 to 3 times the average particle diameter of the filler.

7. The filler alignment film according to any one of claims 1 to 6, wherein,

the filler is conductive particles.

8. A method for manufacturing a connection structure, wherein,

the method for manufacturing a connection structure is a method for manufacturing a connection structure by heating or pressing a filler alignment film in which a filler is aligned in an insulating resin layer between a connection portion of each first article and a connection portion of a second article in a state where a plurality of first articles are aligned on the second article,

as the filler alignment film, a filler alignment film,

in the insulating resin layer, a first group formed by a plurality of fillers is formed by assembling a plurality of fillers corresponding to the appearance of the first article at the position corresponding to the connecting part of the first article to form a second group which is arranged corresponding to the arrangement of the first article,

9. The connection method according to claim 8, wherein,

the first article is a mu LED and the second article is a substrate.

10. A connection structure having the following connection portions: in a state where a plurality of first articles are arranged on a second article, the connection portions of the respective first articles and the connection portions of the second article are connected with each other with a filler interposed therebetween,

the filler in the first group formed by the plurality of fillers constitutes a connection site,

the second group formed by a plurality of first groups exists corresponding to the mounting position of the first article,

the second group is arranged corresponding to the arrangement of the first articles,

11. The connection structure according to claim 10, wherein,

the first article is a mu LED and the second article is a substrate.