KR20230127298A - filler array film - Google Patents

Abstract

Transparency of a connection structure between a first article and a second article obtained by connecting a minute first article such as an electrode of a μLED and a second article such as a substrate for a transparent display using a pillar array film is improved. In the filler array film 1A used for this purpose, the fillers 2 are disposed on the insulating adhesive layer 10, the high-density regions 4 of the filler are regularly arranged at intervals, and each high-density region 4 Then, a plurality of uneven distribution regions 3 of the filler 2 are formed. The average visible light transmittance of the filler array film is 40% or more.

Description

filler array film

The present invention relates to a filler array film in which fillers are arranged in a resin layer, a method for connecting a minute first article to a second article such as a substrate using the filler array film, and a connection structure obtained by the method. . Examples of the minute first article include minute light emitting elements such as mini LEDs and μLEDs.

A μLED display formed by arranging μLEDs, which are microscopic light emitting elements, on a substrate can omit the backlight required for a liquid crystal display, so that the display can be made thinner, and a wide color gamut, high definition, and power saving can be realized. It is also expected as a transparent display application. The case of using as a light source is also the same. Since it can be made lighter and thinner than before, performance improvements such as portability can be expected. Even considering so-called "telework", which has recently become active, various requests for displays are increasing, and it is expected to meet them.

As a method for producing a display in which μLEDs are arranged, in Patent Document 1, a red, blue, and green μLED array formed on a carrier substrate is picked up with a transfer head and placed on a transfer target substrate such as a display substrate. , It is described that a μLED array and a transfer target substrate are bonded to each other by welding of a solder layer, and then a contact line is formed thereon with ITO or the like.

Further, in Patent Literature 2, a μLED formed on a wafer is disposed on a substrate, and an anisotropic conductive film in which conductive particles are dispersed in an adhesive component using a hydrogenated epoxy compound or the like is used to connect the substrate to the substrate, and the wafer is lifted off. This is listed. According to the method using the anisotropic conductive film described in Patent Literature 2, a display using μLED can be easily obtained.

In Patent Literature 3, in connecting an IC chip and an FPC using an anisotropic conductive film having a conductive particle array layer having an area occupancy rate of conductive particles of 35% or less in plan view, in order to increase the efficiency of trapping conductive particles, Using a pulse heater type bonder, in the first step, the IC chip and the FPC are press-fitted into the insulating resin layer of the anisotropic conductive film to bring the electrodes close to the conductive particle array layer for provisional fixation, and in the second step, main bonding is performed. describes a two-step connection method.

Japanese Patent Publication No. 2015-500562 Japanese Unexamined Patent Publication No. 2017-157724 Japanese Unexamined Patent Publication No. 2019-216097

When the size of μLEDs is reduced for high-definition displays, and the size of LED electrodes is also reduced accordingly, in the case of using an anisotropic conductive film in which conductive particles are simply mixed in an insulating material, conductive particles are surely added to the electrodes of individual μLEDs. It becomes difficult to capture.

On the other hand, it is conceivable to use conductive particles having a small particle size to increase the number density of conductive particles in the anisotropic conductive film.

However, if conductive particles having a small particle size are disposed on the entire surface of the anisotropic conductive film at a high number density, there are concerns about adverse effects on design, such as increased short risk and difficulty in transmitting light. Therefore, even if μLED is connected to a substrate for a transparent display using such an anisotropic conductive film, yield deterioration is concerned, and a transparent display with high design freedom cannot be obtained.

Accordingly, an object of the present invention is to obtain a transparent structure as a connection structure between a first article and a second article by connecting a minute first article such as a μLED and a second article such as a substrate for a transparent display using a pillar array film. It is an object of the present invention to provide a pillar array film enabling this, and to provide a connection structure between a first article and a second article obtained by using such a pillar array film.

The present inventor connects the connection part of a minute first article such as an electrode of a μLED to the connection part of a second article such as an electrode of a substrate for a transparent display using a filler arrangement film in which fillers such as conductive particles are arranged in an insulating resin layer. In this case, the fillers in the filler array film form high-density regions regularly arranged corresponding to the arrangement of the first article, and in the high-density region, the fillers form uneven regions corresponding to the connecting parts of the first article. If this is done, unnecessary fillers not involved in the connection can be reduced as much as possible, and the resin flow during connection passes between the high-density regions of the filler and hardly affects the high-density regions, so that the filler is not a part of the first article. It is reliably captured between the connection part and the connection part of the second article, and it is possible to prevent a short circuit in which connection parts adjacent to each other in the direction of the film plane are unnecessarily connected with a filler, and also when the first article is a light emitting element such as μLED, When the filler is concentrated in the high-density area, the light from the light-emitting element transmits portions other than the high-density area with high transmittance, so the light-emitting efficiency of the light-emitting device in which the light-emitting element is mounted is improved, and the present invention was completed. did.

That is, the present invention is a filler array film in which a filler is disposed on an insulating adhesive layer,

The high-density regions of the filler are regularly arranged at intervals,

A plurality of regions of uneven distribution of fillers are formed in each high-density region,

A pillar array film having an average visible light transmittance of 40% or more is provided.

In addition, in the present invention, in a state in which a plurality of first articles are arranged on the second article, the connection part of each first article and the connection part of the second article are heated or As a connection method for connecting by pressing,

As a filler array film,

In the insulating adhesive layer, high-density regions of fillers are regularly arranged at intervals,

A plurality of regions of uneven distribution of fillers are formed in each high-density region,

A connection method using a pillar array film having an average visible light transmittance of 40% or more is provided.

In addition, the present invention is a connection structure in which a connection part of each first article and a connection part of a second article are connected through a filler in a state in which a plurality of first articles are arranged on a second article,

The filler forms a high-density region corresponding to the arrangement of the first article;

A connection structure in which fillers are unevenly distributed in the high-density region corresponding to the connection portion of the first article is provided.

When the pillar array film of the present invention is used, when connecting a minute first article connection portion such as an electrode of a μLED to a second article connection portion such as an electrode of a transparent display substrate by heating or pressing through a pillar array film For example, at least one filler is surely captured between the connection part of the first article and the connection part of the second article, and the connection parts adjacent to each other in the film plane direction, that is, the connection parts of the first article or the connection part of the second article There is a low risk that the filler will be connected between them. Therefore, the risk of short circuit in the case of connecting electronic components, such as microLED, to a board|substrate can be reduced.

In addition, when the first article is a light-emitting element such as a μLED, since the high-density regions of the pillars are arranged corresponding to the arrangement of the light-emitting elements, emission of light from the light-emitting element is difficult to be hindered by the pillars. Accordingly, the light emitting efficiency of the light emitting device in which the light emitting element is mounted is improved.

1 is a layout view of pillars in a pillar array film 1A of an example.
Fig. 2 is a diagram showing the correspondence between the arrangement of pillars in the pillar array film 1A of the embodiment and the connecting parts of articles connected by the pillar array film 1A.
Fig. 3 is a cross-sectional view of the pillar array film 1A of the embodiment.
Fig. 4 is a layout view of the pillars in the pillar array film 1B of the embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail, referring drawings. In each figure, the same reference numerals denote the same or equivalent components.

(filler placement)

1 is a layout view of fillers in a filler array film 1A of one embodiment of the present invention. In this filler arrangement film, conductive particles are arranged as fillers 2 in the insulating resin layer 10. The pillar array film may be used as an anisotropic conductive film or as a conductive film.

The filler array film of the present invention is obtained by heating or pressing the first and second articles through the filler array film in a state in which a plurality of first articles are arranged on the second article, so that the connection portion of each first article and the second article are connected to each other. In this connection state, a filler is sandwiched between the respective connecting parts of the first article and the connecting parts of the second article, and the opposing surfaces of the first article and the second article are made of an insulating resin layer. to make it adhere. Since this pillar array film has an average visible light transmittance of 40% or more, the first article is a μLED, the electrode is a connecting portion of the first article, the second article is a substrate for a transparent display formed with a wiring circuit for μLED, and the electrode. It can be used as an anisotropic conductive film for anisotropically conductively connecting the first article and the second article when used as a connecting portion for the second article. In addition, since the pillar array film of the present invention is used for connection of minute parts, it is necessary to be able to sufficiently visually recognize micro articles through the pillar array film before providing before connection.

Here, the visible light transmittance of the pillar array film is the average transmittance of visible light (wavelength 400 to 700 nm) measured using a visible light transmittance measuring device. The visible light transmittance is measured in the state after curing of the film. This average transmittance should just measure the transmittance of the area of 10 mm x 10 mm, for example.

As such, the visible light transmittance can be measured in the range of 10 × 10 mm. Randomly measuring 5 locations, preferably 10 or more locations in a 10×10 mm area, the visible light transmittance can be calculated from the average.

Alternatively, the visible light transmittance may be measured in such a way that the number density of the conductive particles in the measurement region of the visible light transmittance is within a range of about ±10% of the average number density in the same region. In this way, when μLEDs are disposed on one surface of the substrate, it is easy to check whether or not conductive particles necessary for connection are unevenly distributed, and it is easy to determine whether or not the film used for connection is suitable. In addition, since it can be used to determine whether or not unnecessary conductive particles are present in the film attached to the substrate, it can also contribute to the productivity of the bonded structure. Moreover, it contributes to the improvement of convenience that restrictions are reduced also about the design of a connection structure. Although the range of 10 × 10 mm may be a range (connection area) in which a plurality of μLEDs are arranged even if not on one side, even if the case where the film is cut to a size equal to or larger than this size is assumed, as described above, Similarly, calculating the visible light transmittance is considered to be able to contribute to productivity and the like.

As shown in FIG. 2 , each µLED 20 connected using the pillar array film 1A of this embodiment has two electrodes 21 and is regularly arranged on a wafer 22 in a lattice shape.

Regarding the outer shape and size of the μLED 20, for example, when the outer shape is a rectangle, the long side is 200 μm or less, or less than 150 μm, or less than 50 μm, or less than 20 μm. More specifically, for example, rectangles of 10 μm × 20 μm, 7 μm × 14 μm, and 5 μm × 5 μm are exemplified. Further, the outer shape of the μLED is not limited to a rectangle, and may be, for example, a rhombus shape.

In addition, the shape and size of the electrode 21 are not particularly limited, but when the μLED is small, a rectangle having a long side of 5 μm to 50 μm and a short side of 3 μm to 40 μm is exemplified. The interval Ls of (21) can be appropriately selected according to the usage method. The lower limit is preferably 3 μm or more, more preferably 5 μm or more, from the viewpoint of the convenience of the mounting process. The upper limit is not particularly limited. In the case of a device that is larger than μLED or mini LED and used alone, it may be 3000 μm or less. In the case of display use, it may be 1000 μm or less, 500 μm or less, 150 μm or less, or 20 μm or less.

In the pillar arrangement film 1A, the high-density regions 4 of the pillars 2 are formed corresponding to the outer shape of the μLED (first article) 20, and are regularly arranged at intervals corresponding to the arrangement of the μLEDs. . In each high-density region 4, the unevenly distributed region 3 is formed by the uneven distribution of the fillers 2 at positions corresponding to the individual electrodes (connection portions) 21 of the µLED (first article) 20. The unevenly distributed region 3 and the high-density region 4 can be recognized as the outer shape of the aggregate of the fillers 2 .

Here, the fact that the unevenly distributed region 3 is disposed at a position corresponding to the electrode 21 of the μLED 20 means that when a plurality of μLEDs and the pillar array film are aligned in a predetermined arrangement, when viewed from a plane, This means that the electrode 21 of each μLED 20 and the uneven region 3 overlap, and the space between the electrodes 21 and the space between the uneven region 3 of each μLED 20 overlap, preferably. This means that the electrode 21 is positioned within the unevenly distributed region 3 or that one or more of the conductive particles 2 constituting the unevenly distributed region 3 overlap the electrode 21 .

In addition, the fact that the high-density regions 4 are arranged corresponding to the arrangement of the μLEDs 20 means that each of the μLEDs 20 and the high-density region 4 overlap each other in a plan view due to the alignment described above, and also the space between the μLEDs. and the space between the high-density region 4 overlaps. Preferably, for each μLED 20, among the conductive particles 2 constituting the high-density region 4, the conductive particle deviating from the outer shape of the μLED 20 ( 2) is less than 50% of the area of the outer shape of the μLED 20, more preferably, all the conductive particles 2 constituting the high-density region 4 are located within the outer shape of each μLED 20 say to do

The area of the high-density region 4, that is, the area of the contour shape of the high-density region circumscribed to the conductive particle 2 at the outer periphery among the conductive particles 2 constituting the high-density region 4, is, for example, 10 μm to 1000 μm per side. , but it is preferable to satisfy the following ratio with respect to the outer shape of the corresponding µLED 20. That is, if the lower limit of the ratio of the contour area of the high-density region 4 and the planar view area of the outer shape of the μLED 20 is reduced, the conductive particles 2 can easily enter the outer shape of the μLED 20. This ratio is preferably 0.1 times or more, more preferably 0.2 times or more, and still more preferably 0.5 times or more, in order to facilitate trapping of conductive particles by the electrode. On the other hand, if the upper limit is increased, the fear of insufficient conductive particles captured by the electrode can be avoided, but there is a risk of impairing transparency and aesthetics, so 1.5 times or less is preferable, 1.3 times or less is more preferable, and 1.2 times The following is more preferable.

Further, that the high-density regions 4 are arranged corresponding to the arrangement of μLEDs means that the arrangement direction and pitch of the high-density regions 4 are the same as the arrangement direction and pitch of the μLEDs.

As described above, the localized region 3 of the conductive particles of the pillar array film 1A corresponds to the electrode 21 of the μLED 20, and the high-density region 4 corresponds to the outer shape of the μLED 20, The closest distance between the high-density regions 4 (that is, the distance between a conductive particle constituting a certain high-density region and a conductive particle constituting the high-density region closest to the high-density region) is L1, and in each high-density region The closest distance between the unevenly distributed regions 3 (that is, the distance between a conductive particle constituting a certain unevenly distributed region in each high-density region 4 and a conductive particle constituting the unevenly distributed region closest to that unevenly distributed region) is L2 , and the closest distance between the conductive particles 2 in the unevenly distributed region 3 is L3,

L1>L2>L3

It is desirable to be

The resin flow of the insulating resin layer 10 of the pillar array film 1A in the case of connecting the plurality of μLEDs 20 arranged on the wafer 22 and the substrate by heating and pressing through the pillar array film 1A is in the high-density region. (4) From the point of making it difficult to influence the arrangement|positioning of the conductive particle 2 in (4), L1 or L2 is suitably determined according to the shape of the microLED, arrangement pitch, distance between electrodes, etc.

In addition, a deviation of about ±10% is allowed in the alignment between the unevenly distributed region 3 of the pillar array film 1A, the electrode 21 of the μLED 20, and the electrode on the substrate, so that the area of the unevenly distributed region 3 That is, among the conductive particles 2 constituting the unevenly distributed region 3, the area of the outline circumscribed to the pillar at the outer periphery is 0.5 times the area of the electrode 21 of the corresponding μLED 20 when viewed in plan view. It may be more than 1.8 times or less, and it is preferable to set it as 1.0 times or more and 1.2 times or less. Within this range, since the number of conductive particles is present without excess or deficiency, trapping and short circuiting are compatible, and a good trapping state is easily obtained and easy to check.

In the present invention, in one high-density region 4, the number of unevenly distributed regions 3 can be present according to the number of connection portions of one first article, and in particular, three or less can be present. In the example, two unevenly distributed regions 3 exist.

Regarding the relationship between the closest distance L3 between conductive particles in the unevenly distributed region 3 and the average particle diameter D of the conductive particles 2, the lower limit of these ratios (L3/D) is preferably 0.3 or more; More preferably, it is 0.5 or more, and about the upper limit, it is preferably 4 or less, and more preferably 3 or less.

The disposition of the conductive particles 2 in the unevenly distributed region 3 may be random or regular, but from the point of view of improving the trapping ability of the conductive particles in each electrode 21, the conductive particles may be predetermined. A planar lattice pattern having at least one array axis arranged in a predetermined direction at a pitch is preferable, and examples thereof include a tetragonal lattice, a hexagonal lattice, a tetragonal lattice, a rectangular lattice, and a parallel lattice. In addition, there may be regions with different planar lattice patterns.

(number density of fillers)

The density portion of the filler in the uneven distribution region 3 of the pillar array film 1A is designed according to the object to which the pillar array film 1A is connected. When the filler array film is an anisotropic conductive film, in order to stably connect small parts with the anisotropic conductive film and to avoid a short risk, it is preferable that the conductive particles are less irregularly arranged or agglomerated. In particular, when the particle size of the conductive particles is less than 3 μm, it is preferable that the conductive particles are less irregularly arranged or agglomerated in the unevenly distributed region 3 .

The number density of the fillers in the unevenly distributed region 3 is designed according to the object to which the filler array film 1A is connected. As an example, 50000/mm ² or more is preferable, and 500000/mm ² or more is more preferable. On the other hand, the number density of fillers between the high-density regions 4 is preferably 1000 pieces/mm ² or less, and more preferably substantially zero. Therefore, even if the number density of the fillers is high in the unevenly distributed region 3, the visible light transmittance between the high-density regions 4 can be generally 40% or more, and the visible light transmittance as a whole of the filler array film is 40% or more, preferably. 50% or more can be done.

Further, when the pillar array film 1A is provided to connect a first article such as μLED and a second article such as a substrate for a transparent display, the high-density region 4 is a region sandwiched by the first article and the second article. Therefore, the number density between the unevenly distributed regions 3 in the high-density region 4 does not necessarily have to be zero in order to improve the light transmittance after the first article and the second article are connected. For example, like the filler array film 1B shown in FIG. 4 , the filler 2 may be present between two unevenly distributed regions 3 in the high-density region 4 . In order to reduce unnecessary fillers not involved in connection, the number of fillers between unevenly distributed regions 3 in one high-density region 4 is preferably 50% or less of the number of fillers in unevenly distributed regions 3, and 20 % or less is more preferable.

The filler area occupancy rate in the unevenly distributed region 3 of the filler can be determined so as to maintain the degree of freedom in the layout of objects connected by the filler array film, and may be 5% or more, preferably 8% or more, and 8% or more. 85% or less is more preferable.

The filler area occupancy is the meaning of the conductive particle area occupancy rate in this embodiment, and the number density of conductive particles when viewed from the plane of the unevenly distributed region 3 of the filler array film (piece/mm ² ) × the plane of one conductive particle It can be obtained as the average of the area (mm ² /piece) × 100 when viewed from .

In addition, the number density of conductive particles can be determined by observation using a metal microscope, as well as by image analysis software (e.g., WinROOF (Mitani Shoji Co., Ltd.) or Phase A (registered trademark) (Asahi Kasei Engineering Co., Ltd.)). may be obtained by measuring the observation image by The number observed on the filler array film is counted. When the filler array film is made into remarkably small pieces, it is measured by the number density measured in a state before the pieces are made into pieces.

(filler)

In this embodiment, the particle diameter of the conductive particles 2 serving as the filler is not particularly limited, but the lower limit of the particle diameter is preferably 1 μm or more. The upper limit of the particle diameter is, for example, preferably 50 μm or less, and more preferably 20 μm or less, for example, from the viewpoint of the capturing efficiency of conductive particles in the bonded structure. Depending on the size of the electrode, the particle diameter of the conductive particles is less than 3 μm, preferably less than 2.5 μm, and more preferably less than 2 μm in some cases. When the particle diameter is less than 1 μm, you may handle it as an aggregate of 1 μm or more.

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

Moreover, as the kind of conductive particle, it can be suitably selected from the conductive particle used for the well-known anisotropic conductive film. 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 having insulating fine particles attached to the surface thereof. can be heard You may use 2 or more types together. Among them, the metal-coated resin particles are preferred in that contact with the terminal is easily maintained by repelling the resin particles after being connected, and conduction performance is stable. Further, the surfaces of the conductive particles may be subjected to an insulation treatment that does not impede the conduction characteristics by a known technique.

Further, in the filler array film of the present invention, the filler is an inorganic filler (metal particles, metal oxide particles, metal nitride particles, etc.), an organic filler (resin particles, rubber particles, etc.), Fillers in which organic and inorganic materials are mixed (e.g., particles having a core formed of a resin material and having a metal plated surface (metal-coated resin particles), conductive particles having insulating fine particles adhered to the surface, conductive particles) of which the surface is insulated, etc.), it is appropriately selected according to the performance required for the application, such as hardness and optical performance.

For example, when the filler array film is used as a conductive film or an anisotropic conductive film, conductive particles are contained as a filler. Depending on the purpose of the filler array film, fillers other than conductive particles may be used.

When the filler array film is used for adjustment of color development of microscopic optical elements such as μLEDs or for applications such as black matrices in color displays, known pigments, pigments, light scattering particles, etc. may be used as fillers. When the purpose of the filler array film is an optical film or a matte film, a silica filler, a titanium oxide filler, a styrene filler, an acrylic filler, a melamine filler, or various titanate salts may be used. For the capacitor film, titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, calcium titanate, strontium titanate, barium titanate, barium titanate, tin zirconate titanate, and mixtures thereof can be used. In the adhesive film, polymeric rubber particles, silicone rubber particles, and the like can be contained.

(Cross-sectional structure of filler array film)

FIG. 3 is an A-A sectional view of the pillar array film 1A shown in FIG. 1 . In the unevenly distributed region 3 of the filler array film 1 of this embodiment, the conductive particles 2 are arranged in the insulating resin layer 10.

The insulating resin layer 10 may be composed of a single insulating resin layer or may be composed of a laminate of a plurality of resin layers. It is preferable that the position of the end part of the conductive particle 2 is substantially positioned with one surface of the layer. Rough agreement includes, for example, an error of about ±10% of the particle size. When the insulating resin layer is a laminate of a plurality of resin layers, for example, as shown in FIG. It can be used as the adhesive layer 12 of FIG. The resin constituting the high-viscosity binder resin layer 11 and the adhesive layer 12 can be the same as the binder or adhesive layer constituting the insulating resin layer described in Patent Literature 3, for example. Different fillers may be disposed on different layers and laminated.

However, in order to improve the transparency of the insulating resin layer after the filler array film 1A is provided to connect the first and second articles, the insulating resin layer 10 (high viscosity binder resin layer 11, adhesive layer ( In 12)), it is preferable not to add an inorganic filler as much as possible. Moreover, when using an epoxy resin for the insulating resin layer 10, it is preferable to use the epoxy resin which does not have a conjugated double bond.

Moreover, a rubber component can be added to the insulating resin layer 10 as needed. A rubber component may be incorporated to prevent warping or distortion of the bonded structure. The rubber component is not particularly limited as long as it is an elastomer having high cushioning properties (shock absorption), and examples thereof include acrylic rubber, silicone rubber, butadiene rubber, polyurethane resin (polyurethane-based elastomer), and the like.

The layer thickness of the insulating resin layer 10 is such that, when connecting the μLED and the substrate by heating and pressing the μLED through the pillar array film 1, unnecessary resin flow does not occur in the insulating resin layer, and the pillar array film ( From the point of preventing resin protrusion and blocking when 1) is used as a winding body, the lower limit of the layer thickness is 0.6 times or more of the average particle diameter of the conductive particles 2, preferably 0.9. It is twice or more, more preferably 1 time or more, and the upper limit is 3 times or less, preferably 2 times or less, and more preferably 1.5 times or less. If the layer thickness of the insulating resin layer 10 is less than 0.6 times the average particle diameter of the conductive particles 2, the conductive particles 2 will be exposed from the insulating resin layer 10. When connecting the μLED and the substrate by using the method, it becomes difficult to temporarily attach the pillar array film and the μLED or the substrate. On the other hand, when the ratio exceeds 3 times, excessive flow of resin occurs during connection between the μLED and the substrate, and the flow of the resin causes the conductive particles 2 to flow, degrading the ability to capture the conductive particles in the electrode.

In addition, for manufacturing reasons considering even the arrangement of particles, the lower limit of the layer thickness of the insulating resin layer 10 is preferably 2 μm or more, and 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, since shifting at the time of connection tends to occur when the layer thickness is too large.

In addition, in the case of the present invention, since the μLED itself is small, the size of the μLED and the size of the conductive particles are closer than before. There is a concern that μLEDs tend to shift, but it is preferable that the connection structure avoids this shift. Also for this reason, the thickness of the insulating resin layer 10 is required to fall within the above range.

(Method of manufacturing filler array film)

The pillar array film 1A can be manufactured in the same way as a known anisotropic conductive film, except that the conductive particles are arranged in a specific manner as described above. For example, in the same way as in the manufacturing method of an anisotropic conductive film described in Patent Document 3, first, a mold having concave portions corresponding to the arrangement pattern of conductive particles is prepared, and the mold is filled with conductive particles 2. The high-viscosity binder resin layer 11 formed on the release film is bonded thereon, the conductive particles 2 are press-fitted and electrodeposited into the high-viscosity binder resin layer 11, and the adhesive layer 12 is laminated on the electrodeposited surface. do.

(Connection method using filler array film)

A method of connecting the electrodes of the μLEDs 20 and the electrodes of the substrate in a state in which the plurality of μLEDs 20 are regularly arranged on the wafer 22 using the pillar array film 1A is, first, the electrodes of the substrate. A pillar array film 1A is aligned and pasted on the top, the pillar array film 1A and the µLEDs 20 arranged on the wafer 22 are aligned and bonded, and heated and pressed to form the µLEDs 20. The electrode and the electrode of the substrate are connected. In this case, as described in Patent Literature 3, you may connect by heating and pressurizing in a two-step method. In the case where the conductive particles are solder particles or the like, they may be connected by reflow.

During this heating and pressing, the insulating resin layer of the pillar array film 1 flows, is filled in the gap between the opposite surface of the μLED 20 and the substrate, and is cured to bond the μLED 20 and the substrate. The fluidity of the resin is high between the high-density regions 4 where conductive particles are not disposed, and the fluidity of the resin is low within the high-density regions 4 compared to between the high-density regions 4 . Therefore, the conductive particles 2 in the unevenly distributed regions 3 disposed corresponding to the electrodes of the μLEDs in the high-density region 4 are less susceptible to the influence of the resin flow between the high-density regions 4, and each μLED ( It becomes possible for the electrode 21 of 20 to capture the conductive particle 2 reliably.

In addition, in the high-density region 4, since the unevenly distributed regions 3 are arranged at a distance L2 corresponding to the arrangement of the electrodes 21, the occurrence of short circuits of the electrodes 21 in one µLED is suppressed. .

In addition, since the conductive particles 2 are substantially absent between the high-density regions 4 in the pillar array film 1, the light emitted by the μLEDs 20 after connecting the μLEDs to the substrate is It is not covered by the conductive particles 2 between them. Therefore, the light emitting efficiency of the light emitting device in which the μLED is mounted is improved compared to the case where the pillar array film in which the conductive particles are uniformly present on the entire surface of the film is used.

In addition, the pillar array film may be in the shape of a single piece. Although the size of the singular shape can be designed according to the object, for example, one side can be 5 μm or more and 150 m or less. By doing in this way, it can be expected that it can also be developed for the purpose of adjusting color and light, which will be described later. That is, the first article and the second article may be connected with a film made into a piece shape, or the film made into a piece shape may be disposed only on the electrode. Segmentation can be formed by forming an incision using a mechanical method, a chemical method, a laser, or the like. In addition, the incision does not have to be deep until it reaches the base material, and may be a half cut.

For temporary attachment of the pillar array film, film transfer, and mounting of the μLED on the substrate, a known method such as a method using a stamp material or a laser (laser lift-off method) or a method applied thereto can be used (for example, Japanese Patent Laid-Open No. 9-124020, Japanese Patent Laid-Open No. 2011-76808, Japanese Patent No. 6636017, Japanese Patent No. 6187665, etc.), as long as it is a technique capable of exhibiting the effect of the invention, it is not particularly limited.

(connection structure)

In the connection structure between the µLED 20 and the substrate connected by the above-described method using the pillar array film 1A of the embodiment, the pillar 2 in the uneven distribution region 3 connects the electrode 21 of the µLED 20 to the substrate. It constitutes the connection point of the electrode of [0040] Although the examples are described using µLED as an example, the connection structure may be a mini LED in the present invention.

As described above, since the influence of the flow of the resin at the time of connection hardly affects the arrangement of the conductive particles 2 in the high-density region 4, the high-density region in which a plurality of unevenly distributed regions are aggregated after the connection as well as before the connection is a μLED. It exists corresponding to the mounting position of , and high-density regions are arranged corresponding to the arrangement of μLEDs.

Therefore, the visible light transmittance of the connection structure of the portion of the pillar array film to which the μLED and substrate are not connected is higher than the average visible light transmittance of the pillar array film of 40%, and is preferably 50% or more. Therefore, the luminous efficiency of this connected structure is obtained when a filler array film in which conductive particles are uniformly present on the entire surface of the film at the number density of the conductive particles 2 in the unevenly distributed region 3 of this connected structure is used. markedly improved compared to In addition, the ability to capture conductive particles in each electrode is high, and the rate of occurrence of short circuits is also low.

As described above, in the connection method using the pillar array film of the present invention and the connection structure obtained thereby, the first article is a μLED, the second article is a substrate on which a μLED wiring circuit is formed, and the pillars of the pillar array film are conductive. Although the description was made based on the case of using particles, the present invention is not limited to this.

For example, the first article is made of a light scattering film, a black matrix layer, etc. as the first article, a transparent substrate (a substrate on which μLEDs are mounted), etc. as the second article, and silica or black colored particles as the filler. and the color of the connection structure of the second article may be adjusted.

[Example]

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

Examples 1 to 4, Comparative Examples 1 to 4

(Production of anisotropic conductive film)

An adhesive film was obtained by mixing resin with the resin composition of Table 1, applying it on a peeling film, and drying (60°C, 3 minutes).

On the other hand, conductive particles (average particle diameter of 2.2 μm or 3.2 μm, 0.2 μm Ni-plated resin particles, Sekisui Chemical Industry Co., Ltd.) are arranged in the same manner as described in Japanese Patent No. 6187665, so that the conductive particles are arranged as shown in Table 2. A mold having a concave portion filled with was prepared, the concave portion was filled with conductive particles, the adhesive film of Table 1 was covered, and the conductive particle was press-injected into the adhesive film to prepare an anisotropic conductive film.

(Evaluation of anisotropic conductive film)

Using the anisotropic conductive films of Examples 1 to 4 and Comparative Examples 1 to 4, particle trapping properties, conduction resistance, insulation properties, and visible light transmittance were evaluated as follows. The results are shown in Table 2.

(i) Particle entrapment

The anisotropic conductive films of Examples 1 to 4 and Comparative Examples 1 to 4 were attached to ITO/NdMo patterned glass, and an IC chip for evaluation imitating a μLED was heat-pressed (attained temperature: 150°C, pressurization: 30 Mpa, 10 seconds) on top of it. , a mounting body was obtained. This IC chip for evaluation has an electrode layout in which two bumps of 10 μm × 10 μm (space between bumps of 7 μm) are arranged as a set in a range of 1.5 cm × 1.5 cm at a pitch of 30 μm on one surface.

By observing 100 bumps of this mounting body, the number of conductive particles captured by the bumps was measured. The lowest number in 100 bumps of this number of measurements was evaluated according to the following criteria.

A: 5 or more

B: 3-4

C: 1-2

D: 0

(ii) conduction resistance

The conduction resistance of 100 of the mounting bodies described above was measured and evaluated according to the following criteria.

A: Less than 30Ω

B: 30 Ω or more and less than 100 Ω

C: 100 Ω or more and less than 300 Ω

D: 300Ω or more

(iii) insulation

The conduction resistance was measured for the space between 100 bumps of the mounting body described above, and a resistance of 10 ⁷ Ω or less was determined to be a short circuit. The number of shots was evaluated according to the following criteria.

A: No short

B: 1 short

C: 2 shorts

D: 3 or more shorts

(iv) visible light transmittance

The visible light transmittance (400 to 700 nm) of the anisotropic conductive films of Examples 1 to 4 and Comparative Examples 1 to 4 was measured, and the average transmittance (measurement area: 10 mm × 10 mm) was evaluated according to the following criteria. In addition, UV-2450 (manufactured by Shimadzu Corporation/JIS Z 8729) was used for transmittance measurement. In this case, the measurement sample for the visible light transmittance was left to stand for 1 minute in a 200°C environment in a state where the anisotropic conductive film was attached to the substrate to be in a cured state. It is possible to see how the resin protruding in the bonded structure affects the visible light transmittance. In addition, it is possible to determine whether conductive particles are properly disposed at the location used for connection, and to check whether sufficient transparency is ensured for use in a bonded structure.

A: 50% or more

B: 35% or more

C: 20% or more

D: Less than 20%

From Table 2, it can be seen that when the anisotropic conductive film of the example in which conductive particles are unevenly distributed on the bumps of the μ-chip or μLED is used, all of the particle trapping properties, conduction resistance, insulation, and visible light transmittance are rated B or better.

In contrast, in Comparative Example 1, in which conductive particles are uniformly present throughout the film at the same number density as the number density of conductive particles in the unevenly distributed region of Example 1, the visible light transmittance is low. Further, in Comparative Example 2, where the number density of the entire film was low, the visible light transmittance was rated B, but the particle trapping ability and conduction resistance were poor. In Comparative Example 4, the number density of the entire film is the same as the number density of conductive particles in the unevenly distributed region of Example 1, but since the conductive particles are randomly arranged, the evaluation of insulation properties and visible light transmittance is remarkably poor. , In Comparative Example 3, in which the number density of the entire film was lower than in Comparative Example 4, the evaluation of the particle trapping ability and the conduction resistance was remarkably inferior because the conductive particles were randomly arranged.

1A, 1B filler array film 2 filler, conductive particles
3 ubiquitous region 4 high-density region
10 Insulating resin layer 11 High viscosity binder resin layer
12 adhesive layer 20 first article, μLED
21 electrode 22 wafer
L1 Closest distance between high-density regions L2 Nearest distance between ubiquitous regions
L3 closest distance between fillers in localization region
Distance between electrodes of Ls μLED

Claims (17)

A filler array film in which a filler is disposed on an insulating adhesive layer,
The high-density regions of the filler are regularly arranged at intervals,
A plurality of regions of uneven distribution of fillers are formed in each high-density region,
A pillar array film having an average visible light transmittance of 40% or more. The method of claim 1,
A filler array film in which the high-density region is a rectangle with a side of 10 μm to 1000 μm. According to claim 1 or claim 2,
A filler array film having a number density of 50,000 fillers/mm ² or more in a region where the fillers are unevenly distributed in a high-density region. The method of claim 3,
A filler array film having a number density of 500,000 fillers/mm ² or more in a region where fillers are unevenly distributed in a high-density region. The method according to any one of claims 1 to 4,
A filler array film in which the number density of fillers between high-density regions is 1000 pieces/mm ² or less. The method according to any one of claims 1 to 5,
The filler array film, wherein the number of fillers between unevenly distributed regions in the high-density region is 50% or less of the number of fillers in unevenly distributed regions. The method according to any one of claims 1 to 6,
A filler array film having an area occupancy rate of 5% or more in a region where fillers are unevenly distributed. According to any one of claims 1 to 7,
A filler array film in which fillers are arranged in a tetragonal lattice, a rectangular lattice, or a hexagonal lattice in a unevenly distributed region. The method according to any one of claims 1 to 8,
A pillar array film having a visible light transmittance between high-density regions of 50% or more. A connection in which a plurality of first articles are arranged on a second article, and a connection portion of each first article and a connection portion of the second article are connected by heating or pressing through a filler arrangement film in which a filler is arranged in an insulating resin layer. As a method,
As a filler array film,
In the insulating adhesive layer, high-density regions of fillers are regularly arranged at intervals,
A plurality of regions of uneven distribution of fillers are formed in each high-density region,
A connection method using a pillar array film, wherein the average visible light transmittance of the pillar array film is 40% or more. The method of claim 10,
A connection method in which the area of the contour shape of each high-density region is 0.1 times or more and 1.5 times or less the planar view area of the first article. The method of claim 10,
A connection method in which the area of each unevenly distributed region is 0.5 times or more and 1.8 times or less the area of the connection part of the first article in plan view. According to any one of claims 10 to 12,
The connection method in which the thickness of an insulating resin layer is 3 times or less of the average particle diameter of a filler. According to any one of claims 10 to 13,
A connection method wherein the first article is a μLED and the second article is a substrate for a transparent display. A connection structure in which a connection portion of each first article and a connection portion of a second article are connected via a filler in a state in which a plurality of first articles are arranged on a second article,
The filler forms a high-density region corresponding to the arrangement of the first article;
A connection structure in which fillers are unevenly distributed in a high-density region corresponding to a connection portion of a first article. The method of claim 15
A connection structure in which a visible light transmittance of a portion where the first and second articles are not connected in the connection structure is 50% or more. According to claim 15 or claim 16,
A connection structure in which the first article is a μLED and the second article is a substrate for a transparent display.