JP7087305B2 - Filler-containing film - Google Patents

Description

The present invention relates to a filler-containing film.

The filler-containing film in which the filler is dispersed in the resin layer is used in a wide variety of applications such as a matte film, a capacitor film, an optical film, a label film, an antistatic film, and an anisotropic conductive film. Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4). When the filler-containing film is thermocompression-bonded to an article to be adhered to the filler-containing film, it is possible to suppress unnecessary resin flow of the resin forming the filler-containing film and suppress uneven distribution of the filler. Desirable in terms of physical, mechanical, or electrical properties. In particular, when conductive particles are contained as a filler and the filler-containing film is an anisotropic conductive film used for mounting electronic components such as IC chips, the insulating property can be applied to a high mounting density of electronic components. When the conductive particles are densely dispersed in the resin layer, the densely dispersed conductive particles move unnecessarily due to the resin flow at the time of mounting the electronic component and are unevenly distributed between the terminals, which causes a short circuit.

On the other hand, in order to reduce short circuits and improve workability when temporarily crimping an anisotropic conductive film to a substrate, a photocurable resin layer in which conductive particles are embedded in a single layer and an insulating adhesive layer are used. (Patent Document 5) has been proposed. As a method of using this anisotropic conductive film, temporary pressure bonding is performed in a state where the photocurable resin layer is uncured and has tackiness, and then the photocurable resin layer is photocured to immobilize the conductive particles. After that, the substrate and the electronic component are finally crimped.

Further, in order to achieve the same object as in Patent Document 5, the first connecting layer is an anisotropic conductive film having a three-layer structure sandwiched between the second connecting layer mainly made of an insulating resin and the third connecting layer. Has also been proposed (Patent Documents 6 and 7). Specifically, the anisotropic conductive film of Patent Document 6 has a structure in which the first connecting layer has a single layer of conductive particles arranged in a plane direction on the second connecting layer side of the insulating resin layer. The thickness of the insulating resin layer in the central region between the adjacent conductive particles is thinner than the thickness of the insulating resin layer in the vicinity of the conductive particles. On the other hand, the anisotropic conductive film of Patent Document 7 has a structure in which the boundary between the first connecting layer and the third connecting layer is undulating, and the first connecting layer is on the third connecting layer side of the insulating resin layer. It has a structure in which conductive particles are arranged in a single layer in the plane direction of the above, and the thickness of the insulating resin layer in the central region between adjacent conductive particles is thinner than the thickness of the insulating resin layer in the vicinity of the conductive particles.

Japanese Unexamined Patent Publication No. 2006-15680 Japanese Unexamined Patent Publication No. 2015-138904 Japanese Unexamined Patent Publication No. 2013-103368 Japanese Unexamined Patent Publication No. 2014-183266 Japanese Patent Application Laid-Open No. 2003-64324 Japanese Unexamined Patent Publication No. 2014-060150 Japanese Unexamined Patent Publication No. 2014-060151

However, in the anisotropic conductive film described in Patent Document 5, the conductive particles tend to move during temporary crimping of the anisotropic conductive connection, and the precise arrangement of the conductive particles before the anisotropic conductive connection is performed after the anisotropic conductive connection. There is a problem that it cannot be maintained or the distance between the conductive particles cannot be sufficiently separated. Further, when such an anisotropic conductive film is temporarily pressure-bonded to the substrate, the photocurable resin layer is photocured, and the photocured resin layer in which the conductive particles are embedded and the electronic component are bonded to each other, the electronic component is formed. There is a problem that the conductive particles are difficult to be captured at the end of the bump, and there is a problem that an excessively large force is required to push the conductive particles, and the conductive particles cannot be sufficiently pushed. Further, in Patent Document 5, in order to improve the pushing of the conductive particles, studies from the viewpoint of exposure of the conductive particles from the photocurable resin layer and the like have not been sufficiently made.

Therefore, instead of the photocurable resin layer, the conductive particles are dispersed in the insulating resin layer which becomes highly viscous at the heating temperature at the time of anisotropic conductive connection, and the fluidity of the conductive particles at the time of anisotropic conductive connection is suppressed. At the same time, it is conceivable to improve workability when the anisotropic conductive film is attached to an electronic component. However, even if the conductive particles are precisely arranged on such an insulating resin layer, if the resin layer flows at the time of anisotropic conductive connection, the conductive particles also flow at the same time, so that the catchability of the conductive particles can be improved. It is difficult to sufficiently reduce short circuits, and it is difficult to maintain the initial precise arrangement of the conductive particles after the anisotropic conductive connection, and it is also difficult to keep the conductive particles separated from each other.

Further, in the case of the anisotropic conductive film having a three-layer structure described in Patent Documents 6 and 7, although no problem is found in the anisotropic conductive connection characteristics which are the basic points, since the anisotropic conductive film has a three-layer structure, the manufacturing cost is high. From the viewpoint, it is required to reduce the manufacturing man-hours. Further, in the vicinity of the conductive particles on one side of the first connecting layer, the whole or a part of the first connecting layer is greatly raised along the outer shape of the conductive particles, and the insulating resin layer itself forming the first connecting layer is flat. Instead, since the conductive particles are held in the raised portion, there is a concern that there will be many design restrictions for improving the holding of the conductive particles and the catchability by the terminals.

On the other hand, in the present invention, in a filler-containing film such as an anisotropic conductive film, even if a three-layer structure is not essential, and in the vicinity of the filler of the resin holding the filler such as conductive particles. Even if the entire or part of the resin layer is not raised larger than the outer shape of the filler, it is possible to suppress unnecessary movement of the filler due to the flow of the resin layer during thermal pressure bonding of the filler-containing film, and in particular, the filler-containing film is different. When configured as a anisotropic conductive film, it is an object to improve the catchability of conductive particles and reduce short circuits.

The present inventor has obtained the following findings regarding the relationship between the surface shape in the vicinity of the filler of the resin layer and the viscosity of the resin layer for a filler-containing film having a filler dispersion layer in which fillers such as conductive particles are dispersed in the resin layer. That is, in the anisotropic conductive film described in Patent Document 5, the surface of the insulating resin layer (that is, the photocurable resin layer) itself on the side where the conductive particles are embedded is flat, whereas ( i) When the filler such as conductive particles is exposed from the resin layer, the surface of the resin layer around the filler is inclined so as to be recessed with respect to the tangent plane of the resin layer in the central portion between the adjacent fillers. , A part of the surface of the resin layer is chipped, and as a result, when the filler-containing film is heat-bonded to the article and the filler is bonded to the article, it is unnecessary and may hinder the bonding between the filler and the article. The amount of resin can be reduced, and (ii) when the filler is buried in the resin layer without being exposed from the resin layer, the resin layer directly above the filler and the resin layer in the central portion between the adjacent fillers. If minute undulations (hereinafter, simply referred to as undulations) such as undulations, which are recognized as traces of filler embedding, are formed on the tangent plane of the undulations, the amount of resin is small in the dented portion of the undulations. This makes it easier for the filler to be pushed into the article when the filler-containing film is crimped onto the article. (Iii) Therefore, when two opposing articles are crimped via the filler-containing film, the opposite article Good connection between the sandwiched filler and the article, in other words, the catchability of the filler in the article or the consistency of the arrangement state of the filler sandwiched between the articles before and after crimping is improved, and further, the filler-containing film We found that it would be easier to inspect products and check the usage surface. In addition, it has been found that such a dent in the resin layer can be formed by adjusting the viscosity of the resin layer into which the filler is pushed when the filler dispersion layer is formed by pushing the filler into the resin layer.

The present invention is based on the above findings, and is a filler-containing film having a filler dispersion layer in which the filler is dispersed in the resin layer.
The surface of the resin layer near the filler has an inclination or undulation with respect to the tangent plane of the resin layer in the central portion between the adjacent fillers.
In the slope, the surface of the resin layer around the filler is chipped with respect to the tangent plane.
In the undulation, the amount of resin in the resin layer directly above the filler is smaller than that when the surface of the resin layer directly above the filler is on the tangent plane.
The CV value of the particle size of the filler is 20% or less,
Area occupancy rate of filler calculated by the following equation Area occupancy rate (%) = [Number density of fillers in plan view] x [Average of plane view area of one filler] x 100
Provided is a filler-containing film having a content of 0.3% or more.

Further, the present invention is a method for producing a filler-containing film, which comprises a step of forming a filler dispersion layer in which the filler is dispersed in the resin layer.
The steps of forming the filler dispersion layer include a step of retaining a filler having a particle size CV value of 20% or less on the surface of the resin layer.
It has a step of pushing the filler held on the surface of the resin layer into the resin layer.
In the step of holding the filler on the surface of the resin layer, the filler is dispersed on the surface of the resin layer, and the area occupancy rate of the filler calculated by the following equation on the surface of the resin layer = [in plan view] Number of fillers Density] x [Average plane area of one filler] x 100
Is 0.3% or more
In the step of pushing the filler into the resin layer, the surface of the resin layer near the filler has an inclination or undulation with respect to the tangent plane of the resin layer in the central portion between the adjacent fillers, and in the inclination, the resin layer around the filler. The surface of the resin layer is chipped with respect to the tangent plane, and the amount of resin in the resin layer directly above the filler is smaller in the undulations than when the surface of the resin layer directly above the filler is in the tangent plane. Provided is a method for producing a filler-containing film for adjusting the viscosity, pressing speed or temperature of a resin layer when the filler is pushed.

The filler-containing film of the present invention has a filler dispersion layer in which the filler is dispersed in the resin layer. In this filler-containing film, the surface of the resin layer forming the surface of the filler dispersion layer in the vicinity of the filler is inclined so as to be recessed with respect to the tangent plane of the resin layer in the central portion between the adjacent fillers. Has undulations with respect to the tangent plane. More specifically, when the filler is exposed from the resin layer, the resin layer around the exposed filler is inclined, and the filler is buried in the resin layer without being exposed from the resin layer. If so, the resin layer directly above the filler has undulations. The undulations may also exist when the filler embedded in the resin layer comes into contact with the surface of the resin layer at one point.

This inclination and undulation is formed in the filler-containing film produced by the method for producing a filler-containing film of the present invention. That is, according to the method for producing a filler-containing film of the present invention, the filler is embedded in the resin layer by pushing the filler into the resin layer. Therefore, depending on the degree of embedding in the vicinity of the filler, when the entire filler is embedded in the resin layer and the resin of the resin layer is present directly above the filler (see, for example, FIGS. 4 and 6), or when the filler is used. There are cases where the top is exposed from the resin layer and the resin layer near the filler is dragged into the interior by being dragged by the filler (see, for example, FIGS. 1B and 2), or both are mixed. exist. From the point of view of the forming mechanism, the slope is a slope formed around the filler by the resin layer in the vicinity of the filler being dragged by the filling of the filler and entering the inside. Further, the undulation is a waviness formed directly above the conductive particles as a trace of the embedding when the entire filler is embedded in the resin layer by embedding the filler.

Thus, tilting and undulations are formed when the filler is pushed into a relatively viscous resin layer, so the presence of tilting or undulating in the resin layer allows the resin layer to form tilting or undulating. It means that it has a high viscosity. When the resin layer has a high viscosity, unnecessary resin flow can be suppressed during thermocompression bonding of the filler-containing film to the article, and the filler can be suppressed from being washed away by the resin flow. Further, since there is no resin that interferes with the bonding between the filler and the article during thermocompression bonding or the amount is reduced, the resin layer hinders the bonding between the article and the filler even if the resin layer has a high viscosity. There is no such thing.

Further, when the resin layer is made of a high-viscosity resin capable of forming an inclination or undulation, the thickness of the resin layer itself is reduced, and the resin layer and the resin layer having a lower viscosity are lower than the resin layer. By laminating the resin layer of No. 2, it is possible to maintain the adhesive performance of the filler-containing film when the filler-containing film is heat-bonded to the article and suppress unnecessary flow of the filler during the heat-bonding. Making the resin layer thinner also has the effect of making it easier to take a margin for the heating and pressurizing conditions of the connection tool. This effect is more remarkable when the variation in the particle size of the filler is small. In the present invention, since the CV value of the particle size of the filler is as low as 20% or less, the above-mentioned effect can be sufficiently exhibited.

In addition, since the inclination and undulation of the resin layer exist in the vicinity of the filler, it is possible to easily determine the quality of the dispersed state of the filler by observing the appearance of the filler-containing film at the time of manufacturing the filler-containing film. ..

When the resin layer has the above-mentioned inclination or undulation, unnecessary flow of the resin layer can be reduced when the filler-containing film is pressure-bonded to the article to be adhered to the filler-containing film from the filler side of the filler-containing film. The effect is also obtained. Therefore, for example, when the filler-containing film is configured as an anisotropic conductive film, a resin that is unnecessary for anisotropic conductive connection in which the first electronic component and the second electronic component are thermocompression bonded via the anisotropic conductive film. The influence of flow can be minimized, and the catchability of conductive particles at the time of anisotropic conductive connection is improved.

Further, due to the inclination, the amount of resin in the vicinity of the filler is reduced by the amount of inclination and undulation as compared with Patent Documents 6 and 7. Therefore, when the filler-containing film is pressure-bonded to the article, the resin flow is reduced and the filler is easily pressed against the article. Further, when the two articles are crimped through the filler-containing film, the resin is less likely to interfere with the sandwiching of the filler and the tendency of the filler to be flattened. Further, since the amount of resin around the filler is reduced due to the inclination, the resin flow that leads to the unnecessary flow of the filler is reduced. Therefore, the catchability of the filler in the article is improved, and in particular, when the filler-containing film is formed as an anisotropic conductive film, the catchability of the conductive particles at the terminals is improved, so that the conduction reliability is improved.

Even when the insulating resin layer directly above the conductive particles buried in the insulating resin layer has undulations, the pressing force from the terminal is likely to be applied to the conductive particles at the time of anisotropic connection, as in the case where there is an inclination. .. This is because the amount of resin directly above the conductive particles is reduced due to the dents caused by the undulations. Therefore, the catchability of the conductive particles at the terminals is improved and the conduction reliability is improved as compared with the case where the resin is flatly deposited directly on the conductive particles (see FIG. 8).

As described above, according to the filler-containing film of the present invention, unnecessary resin flow can be suppressed when the filler-containing film is pressure-bonded to the article to be adhered to the filler-containing film, thereby suppressing unnecessary flow of the filler. It can improve the bondability between the filler and the article.

Therefore, when the filler-containing film of the present invention is configured as an anisotropic conductive film and the first electronic component and the second electronic component are connected by using the anisotropic conductive film, the conductive particles on the terminals are difficult to flow. Therefore, the catchability of the conductive particles is improved, and the arrangement of the conductive particles at the time of anisotropic conductive connection can be precisely controlled. Therefore, for example, it can be used for connecting fine-pitch electronic components having a terminal width of 6 μm to 50 μm and a space between terminals of 6 μm to 50 μm. Also, when the size of the conductive particles is less than 3 μm (for example, 2.5 to 2.8 μm), the effective connection terminal width (the width of the pair of terminals facing each other at the time of connection, which overlap in a plan view). ) Is 3 μm or more, and the shortest distance between terminals is 3 μm or more, electronic components can be connected without causing a short circuit.

In addition, since the arrangement of conductive particles can be precisely controlled, when connecting electronic components with a normal pitch, the layout of the area where the conductive particles are arranged and the area where the number density of the conductive particles is changed is the terminal of various electronic components. It is possible to correspond to the layout of.

Further, in the filler-containing film of the present invention, if the resin layer directly above the filler embedded in the resin layer has a dent due to the above-mentioned undulations, the position of the filler can be clearly known by observing the appearance of the filler-containing film. The product inspection is facilitated, and the front and back sides of the film surface can be easily identified. Therefore, when the filler-containing film is pressure-bonded to the article, it becomes easy to confirm which film surface of the filler-containing film is to be attached to the article. Similar advantages can be obtained when producing a filler-containing film.

In addition, according to the filler-containing film of the present invention, it is not always necessary to photo-cure the resin layer in order to fix the arrangement of the filler. Therefore, when the filler-containing film is thermocompression bonded to the article, the resin layer is formed. Can have tackiness. Therefore, the workability when the filler-containing film and the article are temporarily crimped is improved, and the workability is also improved when the second article is further crimped after the temporary crimping.

On the other hand, according to the method for producing a filler-containing film of the present invention, the viscosity of the resin layer when the filler is embedded in the resin layer is adjusted so that the above-mentioned inclination or undulation is formed in the resin layer. Therefore, the filler-containing film of the present invention having the above-mentioned effects can be easily produced.

FIG. 1A is a plan view showing the arrangement of conductive particles of the anisotropic conductive film 10A of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 1B is a cross-sectional view of an anisotropic conductive film 10A according to an embodiment of the filler-containing film of the present invention. FIG. 2 is a cross-sectional view of the anisotropic conductive film 10B of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 3A is a cross-sectional view of the anisotropic conductive film 10C of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 3B is a cross-sectional view of the anisotropic conductive film 10C'of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 4 is a cross-sectional view of the anisotropic conductive film 10D of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 5 is a cross-sectional view of the anisotropic conductive film 10E of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 6 is a cross-sectional view of the anisotropic conductive film 10F of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 7 is a cross-sectional view of an anisotropic conductive film 10G according to an embodiment of the filler-containing film of the present invention. FIG. 8 is a cross-sectional view of an anisotropic conductive film 10X which is a comparative example of the filler-containing film of the present invention. FIG. 9 is a cross-sectional view of the anisotropic conductive film 10H of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 10 is a cross-sectional view of the anisotropic conductive film 10I of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 11A is a top photograph of the anisotropic conductive film of the embodiment, which is one aspect of the filler-containing film of the present invention. FIG. 11B is a top photograph of the anisotropic conductive film of the embodiment, which is one aspect of the filler-containing film of the present invention.

Hereinafter, an example of the filler-containing film of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals represent the same or equivalent components.

<Overall composition of filler-containing film>
FIG. 1A is a plan view illustrating the particle arrangement of the filler-containing film 10A according to the embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the line XX. The filler-containing film 10A is used as an anisotropic conductive film, and is a filler 1 in which conductive particles are dispersed in an insulating resin layer 2.

The filler-containing film 10A can be in the form of a long film having a length of 5 m or more, and can also be a wound body wound around a winding core.

The filler-containing film 10A is composed of a filler dispersion layer 3, and in the filler dispersion layer 3, the filler 1 is regularly dispersed in a state where the filler 1 is exposed on one side of the resin layer 2. In the plan view of the film, the fillers 1 are not in contact with each other, the fillers 1 are regularly dispersed in the film thickness direction without overlapping with each other, and the filler layers are aligned in the film thickness direction. Is formed.

An inclination 2b is formed on the surface 2a of the resin layer 2 around the filler 1 in the vicinity of each filler 1 with respect to the tangent plane 2p of the resin layer 2 in the central portion between the adjacent fillers. As will be described later, in the filler-containing film of the present invention, undulations 2c may be formed on the surface of the resin layer directly above the filler 1 embedded in the resin layer 2 (FIGS. 4 and 6).

In the present invention, "inclination" means a state in which the flatness of the surface of the resin layer 2 is impaired in the vicinity of the filler 1, and a part of the resin layer is chipped with respect to the tangent plane 2p to reduce the amount of resin. Means. On the other hand, the "undulation" means a state in which the resin is reduced due to the presence of undulations on the surface of the resin layer directly above the conductive particles and the presence of dents associated with the undulations. These are recognized in comparison with the portion directly above the filler and the flat surface portion between the fillers (2f in FIGS. 1B, 4, 6; outside 2b in FIG. 11A, outside 2c in FIG. 11B). be able to. In some cases, the starting point of undulation may exist as an inclination.

<Dispersed state of filler>
The dispersed state of the filler in the present invention includes a state in which the filler 1 is randomly dispersed and a state in which the filler 1 is dispersed in a regular arrangement. In either case, it is preferable that the positions in the film thickness direction are aligned, in order to suppress unnecessary flow of the filler when the filler-containing film is thermocompression bonded to the article to be the adherend of the filler-containing film. When the filler-containing film is an anisotropic conductive film, it is preferable from the viewpoint of capture stability at the terminals of electronic components. Here, the fact that the positions of the fillers 1 in the film thickness direction are aligned is not limited to the alignment in a single depth in the film thickness direction, and the positions of the fillers 1 are aligned at or near the front and back interfaces of the resin layer 2. Includes aspects in which conductive particles are present.

In order to make the optical, mechanical or electrical characteristics of the filler-containing film uniform, in particular, when the filler is made of conductive particles and the filler-containing film is made of an anisotropic conductive film, the conductive particles are captured and short-circuited. It is preferable that the fillers 1 are regularly arranged in a plan view of the film in order to achieve both suppression and suppression. The mode of arrangement is not particularly limited, and for example, a square lattice arrangement can be used as shown in FIG. 1A in a plan view of the film. In addition, as an embodiment of the regular arrangement of the filler, a lattice arrangement such as a rectangular lattice, an orthorhombic lattice, a hexagonal lattice, and a triangular lattice can be mentioned. A plurality of grids having different shapes may be combined.
As an aspect of the arrangement of the fillers, a particle array in which the fillers are linearly arranged at predetermined intervals may be arranged in parallel at predetermined intervals. Further, the filler may be removed regularly in a predetermined direction of the film.

By making the fillers non-contact with each other and forming them in a regular arrangement such as a grid pattern, pressure can be evenly applied to each filler 1 when the filler-containing film is pressure-bonded to an article, and variations in the connection state can be reduced. can. In addition, lot management becomes possible by repeatedly allowing the filler to be removed in the longitudinal direction of the film, or by gradually increasing or decreasing the location where the filler is removed in the longitudinal direction of the film. It is also possible to impart traceability (property that enables tracking) to the existing connection structure. This is also effective in preventing forgery, authenticity determination, unauthorized use prevention, etc. of the filler-containing film and the connection structure using the filler-containing film.

Therefore, when the filler-containing film is formed as an anisotropic conductive film, the conductive particles are arranged in a non-contact regular arrangement so that the anisotropic conductive film is used to form the first electronic component and the second electron. It is possible to reduce the variation in conduction resistance when components are anisotropically conductively connected. Whether or not the fillers have a regular arrangement can be determined, for example, by observing whether or not the predetermined arrangement of the fillers is repeated in the longitudinal direction of the film. Further, when the filler-containing film is formed as an anisotropic conductive film, the anisotropic conductivity is that the conductive particles are regularly arranged in the plan view of the film and the positions in the film thickness direction are aligned. It is more preferable to achieve both capture stability and short-circuit suppression at the terminal when the first electronic component and the second electronic component are anisotropically conductively connected using a film.

On the other hand, when the space between the terminals of the electronic components to be connected is wide and short circuits are unlikely to occur, the conductive particles are not arranged regularly, and if there are conductive particles to the extent that they do not interfere with conduction, they are randomly dispersed. May be.

When the fillers are arranged regularly, the lattice axis or the arrangement axis of the arrangement may be parallel to the longitudinal direction or the direction orthogonal to the longitudinal direction of the filler-containing film, and may intersect the longitudinal direction of the filler-containing film. Also, it can be determined according to the article to be crimped with the filler-containing film. For example, when the filler-containing film is an anisotropic conductive film, the lattice axis or arrangement axis of the conductive particles arranged regularly is determined according to the terminal width, terminal pitch, layout, etc. connected by the anisotropic conductive film. be able to. More specifically, when the filler-containing film is an anisotropic conductive film for fine pitch, the lattice axis A of the conductive particles 1 is oriented with respect to the longitudinal direction of the anisotropic conductive film 10A as shown in FIG. 1A. The angle θ formed by the longitudinal direction (the short side direction of the film) of the terminal 20 connected by the anisotropic conductive film 10A and the lattice axis A is preferably 6 ° to 84 °, more preferably 11 ° to. Set to 74 °.

In the filler-containing film, the distance between the fillers can also be determined according to the article to be connected. When the filler-containing film is an anisotropic conductive film, the distance between the particles of the conductive particles to be the filler 1 is anisotropic. It can be appropriately determined according to the size and terminal pitch of the terminals connected by the conductive film. For example, when the anisotropic conductive film is made to correspond to COG (Chip On Glass) of fine pitch, the distance between the closest fillers (that is, the distance between the closest particles) is set to the conductive particle diameter D from the viewpoint of preventing the occurrence of short circuit. It is preferably 0.5 times or more, and more preferably 0.7 times or more. On the other hand, the upper limit of the distance between the closest fillers can be determined depending on the purpose of the filler-containing film. For example, from the viewpoint of difficulty in manufacturing the filler-containing film, the distance between the closest particles is preferably set to the conductive particle diameter D. It can be 100 times or less, more preferably 50 times or less. Further, from the viewpoint of the capture property of the conductive particles 1 at the terminal at the time of anisotropic conductive connection, the distance between the closest particles is preferably 4 times or less of the conductive particle diameter D, and more preferably 3 times or less. preferable.

Further, in the filler-containing film of the present invention, the area occupancy of the filler calculated by the following formula is set to 0.3% or more in order to exhibit the effect of containing the filler.
Area occupancy (%) = [Number density of fillers in plan view] x [Average of area in plan view of one filler] x 100

This area occupancy is an index of the thrust required for the pressing jig to press the filler-containing film onto the article. As will be described later, the area occupancy rate is preferably 35% or less, more preferably 30% or less, from the viewpoint of suppressing the thrust required for the pressing jig for crimping the filler-containing film to the article.

Here, as the measurement region of the number density of the filler, a rectangular region having a side of 100 μm or more is arbitrarily set at a plurality of locations (preferably 5 or more, more preferably 10 or more), and the total area of the measurement region is 2 mm. It is preferably ² or more. The size and number of individual regions may be appropriately adjusted according to the state of the number density. As an example of the case where the number density of the anisotropic conductive film for fine pitch applications is relatively large, an observation image of 200 locations (2 mm ² ) in an area of 100 μm × 100 μm arbitrarily selected from a filler-containing film with a metallurgical microscope or the like. By measuring the number density using and averaging them, the "number density of fillers in a plan view" in the above equation can be obtained. When the filler-containing film is an anisotropic conductive film, the region having an area of 100 μm × 100 μm is a region where one or more bumps are present in a connecting object having a space between bumps of 50 μm or less.

As long as the area occupancy is within the above range, the value of the number density is not particularly limited, but when the filler-containing film is an anisotropic conductive film, the number density is 30 pieces / mm ² in practice. The above may be sufficient, preferably 150 to 70,000 pieces / mm ² , particularly preferably 6000 to 42,000 pieces / mm ² , more preferably 10,000 to 40,000 pieces / mm ² , and even more preferably 15,000 for fine pitch applications. ~ 35,000 pieces / mm ² .

The density of the number of fillers can be determined by observing with a metallurgical microscope as described above, or by measuring an observed image with image analysis software (for example, WinROOF, Mitani Corporation, etc.). The observation method and the measurement method are not limited to the above.

Further, the average of the planar viewing area of one filler can be obtained by measuring the observation image on the film surface with a metal microscope or an electron microscope such as SEM. Image analysis software may be used. The observation method and the measurement method are not limited to the above.

As described above, the area occupancy is preferably 35% or less, more preferably 30% or less, for the following reasons. That is, conventionally, in the anisotropic conductive film, in order to correspond to a fine pitch, the interparticle distance of the conductive particles is narrowed and the number density is increased as long as a short circuit is not generated. However, as the number of terminals of electronic components increases and the total connection area per electronic component increases, when the number density of conductive particles is increased, the anisotropic conductive film is thermocompression bonded to the electronic components. There is a concern that the thrust required for the jig will increase, and there will be a problem that the conventional pressing jig will not be sufficiently pressed. The problem of thrust required for such a pressing jig is not limited to the anisotropic conductive film, but is common to all filler-containing films. On the other hand, in the present invention, the area occupancy is preferably 35% or less, more preferably 30% or less as described above, and the thrust required for the pressing jig for thermocompression bonding the filler-containing film to the article is applied. suppress.

<Filler>
In the present invention, the filler 1 includes known inorganic fillers (metals, metal oxides, metal nitrides, etc.), organic fillers (resin particles, rubber particles, etc.), and organic materials, depending on the use of the filler-containing film. Fillers mixed with inorganic materials (for example, particles whose core is formed of a resin material and whose surface is metal-plated (metal-coated resin particles), particles in which insulating fine particles are adhered to the surface of conductive particles, conductive particles It is appropriately selected from those whose surface is insulated, etc.) according to the performance required for the application such as hardness and optical performance. For example, in the optical film and the matte film, silica filler, titanium oxide filler, styrene filler, acrylic filler, melamine filler, various titanium salts and the like can be used. For film for condensers, titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, calcium titanate, strontium titanate, barium titanate, barium titanate, lead zirconate titanate and mixtures thereof. Etc. can be used. The adhesive film can contain polymer-based rubber particles, silicone rubber particles, and the like. The anisotropic conductive film contains conductive particles. Examples of the 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 adhered to the surface. .. Two or more types can be used together. Above all, it is preferable that the metal-coated resin particles are repulsed after being connected, so that the contact with the terminal is easily maintained and the conduction performance is stabilized. Further, the surface of the conductive particles may be subjected to an insulating treatment that does not interfere with the conduction characteristics by a known technique. The fillers listed for each use are not limited to the above-mentioned uses, and may be contained in a filler-containing film for other uses, if necessary. Further, in the filler-containing film for each application, two or more kinds of fillers can be used in combination as needed.

The shape of the filler is appropriately selected from spherical, ellipsoidal, columnar, needle-shaped, a combination thereof, and the like, depending on the use of the filler-containing film. A spherical shape is preferable because it is easy to confirm the filler arrangement and it is easy to maintain a uniform shape. In particular, in the anisotropic conductive film, it is preferable that the conductive particles are substantially true spheres. By using substantially true spheres as the conductive particles, for example, in producing an anisotropic conductive film in which conductive particles are arranged using a transfer type as described in JP-A-2014-60150, transfer is performed. Since the conductive particles roll smoothly on the mold, the conductive particles can be filled in a predetermined position on the transfer mold with high accuracy. Therefore, the conductive particles can be accurately arranged.

Here, the substantially true sphere means that the sphericity calculated by the following equation is 70 to 100.

In the above formula, So is the area of the circumscribed circle of the filler in the planar image of the filler, and Si is the area of the inscribed circle of the filler in the planar image of the filler.

In this calculation method, a planar image of the filler is taken in the plane view and cross section of the filler-containing film, and the area of the circumscribing circle and the area of the inscribed circle of 100 or more (preferably 200 or more) arbitrary fillers in each planar image. Is measured, the average value of the area of the extrinsic circle and the average value of the area of the inscribed circle are obtained, and it is preferable to use So and Si as described above. Further, it is preferable that the sphericity is within the above range in both the surface field of view and the cross section. The difference in sphericity between the surface field of view and the cross section is preferably 20 or less, more preferably 10 or less. Since the inspection at the time of production of the filler-containing film is mainly performed on the surface field of view, and the detailed quality judgment after thermocompression bonding to the article is performed on both the surface field of view and the cross section, it is preferable that the difference in sphericity is small. If the sphericity is a single filler, it can be obtained by using a wet flow type particle size / shape analyzer FPIA-3000 (Malburn Co., Ltd.).

The particle size D of the filler is appropriately determined according to the use of the filler-containing film. For example, in an anisotropic conductive film, it is preferably 1 μm or more and 30 μm or less, more preferably 30 μm or less, in order to cope with variations in wiring height, suppress an increase in conduction resistance, and suppress the occurrence of short circuits. It is 2.5 μm or more and 9 μm or less. Depending on the object to be connected, one larger than 9 μm may be suitable.

The particle size D of the filler before being dispersed in the resin layer 2 can be measured by a general particle size distribution measuring device, and the average particle size can also be determined by using the particle size distribution measuring device. FPIA-3000 (Malburn Co., Ltd.) can be mentioned as an example of the particle size distribution measuring device. On the other hand, the particle size D of the filler in the filler-containing film can be obtained from electron microscope observation such as SEM. In this case, it is desirable that the number of samples for measuring the particle size D is 200 or more. When the shape of the filler is not spherical, the maximum length or the diameter of the shape imitating the spherical shape can be the particle diameter D of the filler.

In the present invention, the variation in the particle size D of the filler in the filler-containing film is set to a CV value (standard deviation / average) of 20% or less. By setting the CV value to 20% or less, the filler-containing film is likely to be pressed evenly when the filler-containing film is pressure-bonded to the article, and the pressing force is locally concentrated especially when the fillers are arranged. Can be prevented and contribute to the stability of the connection. In addition, it is possible to accurately evaluate the connection state by indentation after connection. Specifically, when the filler-containing film is configured as an anisotropic conductive film, even if the terminal size is large (FOG, etc.) in the inspection after the anisotropic conductive film and the anisotropic conductive connection of the electronic component. Even a small object (COG, etc.) can accurately confirm the connection state by indentation. Therefore, it can be expected that the inspection after the anisotropic connection becomes easy and the productivity of the connection process is improved.

Here, the variation in particle size can be calculated by an image-type particle size analyzer or the like. The particle size of the filler as the raw material particles of the filler-containing film, which is not contained in the filler-containing film, can also be determined by using the above-mentioned wet flow type particle size / shape analyzer FPIA-3000 (Malburn Co., Ltd.). In this case, if the number of fillers is 1000 or more, preferably 3000 or more, more preferably 5000 or more, the variation of the filler alone can be accurately grasped. When the filler is arranged on the filler-containing film, it can be obtained from a plane image or a cross-sectional image in the same manner as the sphericity.

<Resin layer>
(Viscosity of resin)
In the present invention, the minimum melt viscosity of the resin layer 2 is not particularly limited and can be appropriately determined depending on the use of the filler-containing film, the method for producing the filler-containing film, and the like. For example, as long as the above-mentioned inclination 2b or undulation 2c can be formed, it may be about 1000 Pa · s depending on the method for producing the filler-containing film. On the other hand, as a method for producing a filler-containing film, when the filler is held on the surface of the resin layer in a predetermined arrangement and the filler is pushed into the resin layer, the resin layer is the lowest in terms of enabling film molding. The melt viscosity is preferably 1100 Pa · s or more.

Further, as described later in the method for producing a filler-containing film, as shown in FIGS. 1B and the like, an inclined 2b is formed around the exposed portion of the filler 1 pushed into the resin layer 2, and FIGS. 4 and 6 show. As shown, the minimum melt viscosity is preferably 1500 Pa · s or more, more preferably 2000 Pa · s or more, still more preferably 3000 to 15000 Pa · s, from the viewpoint of forming undulations 2c directly above the filler 1 pushed into the resin layer 2. -S, especially 3000 to 10000 Pa · s. This minimum melt viscosity can be determined by using a rotary leometer (manufactured by TA instrument) as an example, keeping it constant at a measuring pressure of 5 g, and using a measuring plate having a diameter of 8 mm, and more specifically, a temperature range. It can be obtained by setting a temperature rise rate of 10 ° C./min, a measurement frequency of 10 Hz, and a load fluctuation of 5 g with respect to the measurement plate at 30 to 200 ° C.

By setting the minimum melt viscosity of the resin layer 2 to a high viscosity of 1500 Pa · s or more, it is possible to suppress unnecessary movement of the filler during thermocompression bonding of the filler-containing film to the article, and in particular, the filler-containing film is designated as an anisotropic conductive film. In this case, it is possible to prevent the conductive particles 1 to be sandwiched between the terminals at the time of anisotropic conductive connection from being washed away by the resin flow.

Further, when the filler dispersion layer 3 of the filler-containing film 10A is formed by pushing the filler 1 into the resin layer 2, the resin layer 2 when the filler 1 is pushed is a filler so that the filler 1 is exposed from the resin layer 2. When the resin layer 1 is pushed into the resin layer 2, the resin layer 2 is plastically deformed to form a highly viscous viscous body such that an inclination 2b (FIG. 1B) is formed on the resin layer 2 around the filler 1. When the filler 1 is pushed so as to be buried in the resin layer 2 without being exposed from the resin layer 2, undulations 2c (FIGS. 4 and 6) are formed on the surface of the resin layer 2 directly above the filler 1. A viscous body with such high viscosity. Therefore, the lower limit of the viscosity of the resin layer 2 at 60 ° C. is preferably 3000 Pa · s or more, more preferably 4000 Pa · s or more, still more preferably 4500 Pa · s or more, and the upper limit is preferably 20000 Pa · s or less. It is preferably 15,000 Pa · s or less, and more preferably 10,000 Pa · s or less. This measurement is performed by the same measurement method as the minimum melt viscosity, and a value having a temperature of 60 ° C. can be extracted and obtained.

The specific viscosity of the resin layer 2 when the filler 1 is pushed into the resin layer 2 is preferably 3000 Pa · s or more, more preferably 3000 Pa · s or more, depending on the shape and depth of the inclined 2b and the undulations 2c to be formed. Is 4000 Pa · s or more, more preferably 4500 Pa · s or more, and the upper limit is preferably 20000 Pa · s or less, more preferably 15000 Pa · s or less, still more preferably 10000 Pa · s or less. Further, such a viscosity is preferably obtained at 40 to 80 ° C, more preferably 50 to 60 ° C.

As described above, since the inclination 2b (FIG. 1B) is formed around the filler 1 exposed from the resin layer 2, the flattening of the filler 1 that occurs when the filler-containing film is pressure-bonded to the article The resistance received from the resin layer 2 is reduced as compared with the case where there is no inclination 2b. Therefore, when the filler-containing film is an anisotropic conductive film, the conductive particles are easily pinched at the terminals at the time of anisotropic conductive connection, so that the conduction performance is improved and the catchability is improved.

The slope 2b is preferably along the outer shape of the exposed portion of the filler. This is because, in addition to making it easier for the effect of tilting in connection to appear, it becomes easier to recognize the filler, which makes it easier to perform product inspections in the production of the filler-containing film.

Further, since the undulations 2c (FIGS. 4 and 6) are formed on the surface of the resin layer 2 directly above the filler 1 which is buried without being exposed from the resin layer 2, the article is formed in the same manner as in the case of inclination. When crimping, the pressing force from the article is likely to be applied to the filler. In addition, due to the undulating dents, the amount of resin directly above the filler is reduced compared to when the resin directly above the filler is flat, so that the resin directly above the filler is easily removed during crimping, and the article and the filler are easily removed. The connection status of is good. In particular, when the filler-containing film is an anisotropic conductive film, the terminals and the conductive particles are likely to come into contact with each other at the time of anisotropic conductive connection, so that the catchability of the conductive particles at the terminals is improved and the conduction reliability is improved. Is improved.

A part of the inclination 2b and the undulation 2c may disappear by heat-pressing the resin layer or the like, and the present invention includes this. Further, the filler is exposed at one point on the surface of the resin layer, and there may be an inclination or undulation around the one point, and the present invention also includes this. These aspects are appropriately selected depending on the use of the filler-containing film and the article to be thermocompression bonded. That is, the filler-containing film of the present invention has a high degree of freedom in design, and can be used by reducing the degree of inclination or undulation as necessary, or by partially eliminating the inclination or undulation.

(Layer thickness of resin layer)
In the filler-containing film of the present invention, the ratio (La / D) of the layer thickness La of the resin layer 2 to the particle diameter D of the filler is preferably 0.6 to 10. Here, the particle size D of the filler means the average particle size thereof. If the layer thickness La of the resin layer 2 is too large, the filler tends to be displaced when the filler-containing film is pressure-bonded to the article. Therefore, when the filler-containing film is used as an optical film, the optical characteristics vary. Further, when the filler-containing film is an anisotropic conductive film, the catchability of conductive particles at the terminals connected to the electronic component by anisotropic conductive conduction is lowered. This tendency is remarkable when La / D exceeds 10. Therefore, La / D is more preferably 8 or less, and even more preferably 6 or less. On the contrary, if the layer thickness La of the resin layer 2 is too small and the La / D is less than 0.6, it becomes difficult for the resin layer 2 to maintain the filler 1 in a predetermined particle-dispersed state or a predetermined arrangement. In particular, when the filler-containing film is an anisotropic conductive film and the terminal to be connected is a high-density COG, the ratio (La / D) of the layer thickness La of the insulating resin layer 2 to the conductive particle diameter D is preferable. It is 0.6 to 3, more preferably 0.8 to 2. On the other hand, when the filler-containing film is an anisotropic conductive film and the risk of short circuit is considered to be low due to the bump layout of the electronic components to be connected, the lower limit of the ratio (La / D) is 0.25 or more. May be.

(Composition of resin layer)
In the present invention, the resin layer 2 can be formed from a thermoplastic resin composition, a high-viscosity adhesive resin composition, and a curable resin composition. The resin composition constituting the resin layer 2 is appropriately selected according to the use of the filler-containing film, and whether or not the resin layer 2 has an insulating property is also determined according to the use of the filler-containing film.

Here, the curable resin composition can be formed from, for example, a thermosetting composition containing a thermopolymerizable compound and a thermopolymerization initiator. The thermopolymerizable composition may contain a photopolymerization initiator, if necessary.

When the thermopolymerization initiator and the photopolymerization initiator are used in combination, a photopolymerizable compound that also functions as a photopolymerizable compound may be used, and a photopolymerizable compound is contained separately from the thermopolymerizable compound. You may. Preferably, the photopolymerizable compound is contained separately from the thermopolymerizable compound. For example, a cationic curing initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermal polymerizable compound, a photoradical initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound.

As the photopolymerization initiator, a plurality of types that react with light having different wavelengths may be contained. Thereby, it is possible to properly use the wavelength used for the photocuring of the resin for forming the resin layer into a film at the time of manufacturing the filler-containing film and the photocuring of the resin for crimping the filler-containing film to the article.

When photo-curing is performed during the production of the filler-containing film, all or part of the photopolymerizable compound contained in the resin layer can be photo-cured. By this photo-curing, the arrangement of the filler 1 in the resin layer 2 is maintained or fixed. Therefore, when the filler-containing film is an anisotropic conductive film, it is expected to suppress short circuits and improve the catchability. Further, the viscosity of the resin layer in the manufacturing process of the filler-containing film may be appropriately adjusted by this photocuring.

The blending amount of the photopolymerizable compound in the resin layer is preferably 30% by mass or less, more preferably 10% by mass or less, and more preferably less than 2% by mass. This is because if the amount of the photopolymerizable compound is too large, the thrust applied to the pushing force when the filler-containing film is pressure-bonded to the article increases.

Examples of the heat-polymerizable composition include a heat-radical polymerizable acrylate-based composition containing a (meth) acrylate compound and a heat-radical polymerization initiator, and a heat-cationic polymerizable epoxy-based composition containing an epoxy compound and a heat-cationic polymerization initiator. Examples thereof include compositions. A thermal anionic polymerizable epoxy composition containing a thermal anionic polymerization initiator may be used instead of the thermal cationic polymerization initiator. Further, a plurality of kinds of polymerizable compositions may be used in combination as long as they do not cause any particular trouble. Examples of the combined use include a combined use of a thermally cationically polymerizable compound and a thermally radically polymerizable compound.

Here, as the (meth) acrylate compound, a conventionally known thermopolymerizable (meth) acrylate monomer can be used. For example, a monofunctional (meth) acrylate-based monomer and a bifunctional or higher polyfunctional (meth) acrylate-based monomer can be used.

Examples of the thermal radical polymerization initiator include organic peroxides and azo compounds. In particular, an organic peroxide that does not generate nitrogen that causes bubbles can be preferably used.

If the amount of the thermal radical polymerization initiator used is too small, curing will be poor, and if it is too large, the product life will be shortened. It is 5 to 40 parts by mass.

Examples of the epoxy compound include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, modified epoxy resin thereof, alicyclic epoxy resin and the like, and two or more of these can be used in combination. can. Further, an oxetane compound may be used in combination with the epoxy compound.

As the thermal cationic polymerization initiator, known ones as thermal cationic polymerization initiators of epoxy compounds can be adopted, and for example, iodonium salt, sulfonium salt, phosphonium salt, ferrocenes and the like that generate acid by heat are used. In particular, aromatic sulfonium salts that have good potential for temperature can be preferably used.

If the amount of the thermal cation polymerization initiator used is too small, it tends to cause poor curing, and if it is too large, the product life tends to decrease. Therefore, it is preferably 2 to 60 parts by mass with respect to 100 parts by mass of the epoxy compound. Parts, more preferably 5 to 40 parts by mass.

As the thermal anionic polymerization initiator, a commonly used known curing agent can be used. For example, organic acid dihydrazide, dicyandiamide, amine compound, polyamide amine compound, cyanato ester compound, phenolic resin, acid anhydride, carboxylic acid, tertiary amine compound, imidazole, Lewis acid, blended acid salt, polymercaptan-based curing agent. , Uria resin, melamine resin, isocyanate compound, blocked isocyanate compound and the like, and one of these can be used alone or in combination of two or more. Among these, it is preferable to use a microcapsule type latent curing agent having an imidazole modified product as a nucleus and coating the surface thereof with polyurethane.

The thermopolymerizable composition preferably contains a film-forming resin or a silane coupling agent. Examples of the film-forming resin include phenoxy resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, and polyolefin resin, and two or more of these are used in combination. be able to. Among these, a phenoxy resin can be preferably used from the viewpoint of film forming property, processability, and connection reliability. The weight average molecular weight is preferably 10,000 or more. Examples of the silane coupling agent include an epoxy-based silane coupling agent and an acrylic-based silane coupling agent. These silane coupling agents are mainly alkoxysilane derivatives.

The thermopolymerizable composition may contain an insulating filler in addition to the filler 1 described above in order to adjust the melt viscosity. This includes silica powder and alumina powder. The insulating filler is preferably a fine filler having a particle diameter of 20 to 1000 nm, and the blending amount is 5 to 50 parts by mass with respect to 100 parts by mass of a heat-polymerizable compound (photopolymerizable composition) such as an epoxy compound. Is preferable. The insulating filler contained separately from the filler 1 is preferably used when the use of the filler-containing film is an anisotropic conductive film, but it may not be insulating depending on the use, for example, a minute conductive filler. It may be contained. When the filler-containing film is an anisotropic conductive film, the resin layer forming the filler dispersion layer appropriately contains a finer insulating filler (so-called nanofiller) different from the filler 1 as necessary. Can be done.

In addition to the above-mentioned insulating or conductive filler, the filler-containing film of the present invention contains a filler, a softener, an accelerator, an antioxidant, a colorant (pigment, dye), an organic solvent, an ion catcher agent and the like. It may be contained.

(Position of filler in the thickness direction of the resin layer)
In the filler-containing film of the present invention, the position of the filler 1 in the thickness direction of the resin layer 2 may be such that the filler 1 is exposed from the resin layer 2 as described above, and the filler 1 may be exposed in the resin layer 2 without being exposed. It may be embedded, but the ratio (Lb / D) of the distance Lb of the deepest part of the filler from the tangent plane 2p in the central part between the adjacent fillers (hereinafter referred to as the embedded amount) and the particle diameter D of the filler. ) (Hereinafter referred to as embedding rate) is preferably 60% or more and 105% or less.

By setting the embedding rate (Lb / D) to 60% or more, the filler 1 is maintained in a predetermined particle dispersion state or a predetermined arrangement by the resin layer 2, and by setting it to 105% or less, the filler-containing film is used. It is possible to reduce the amount of resin in the resin layer that acts to cause the filler to flow unnecessarily during pressure bonding with the article.

In the present invention, the value of the embedding rate (Lb / D) is 80% or more, preferably 90% or more, more preferably 96% or more of the total number of fillers contained in the filler-containing film. It means that it is a numerical value of (Lb / D). Therefore, when the embedding rate is 60% or more and 105% or less, the embedding rate of 80% or more, preferably 90% or more, more preferably 96% or more of the total number of fillers contained in the filler-containing film is 60% or more 105. It means that it is less than%.

Since the embedding ratios (Lb / D) of all the fillers are uniform in this way, the pressing load when the filler-containing film is pressure-bonded to the article is uniformly applied to the fillers. Therefore, in the film-bonded body in which the filler-containing film is pressure-bonded to the article, the uniformity of quality such as optical properties and mechanical properties can be ensured. Further, when the filler-containing film is an anisotropic conductive film, the capture state of the conductive particles at the terminals becomes good at the time of anisotropic conductive connection, and the stability of conduction is improved.

For the embedding rate (Lb / D), 10 or more areas with an area of 30 mm ² or more are arbitrarily extracted from the filler-containing film, a part of the cross section of the film is observed with an SEM image, and a total of 50 or more fillers are measured. It can be obtained by. In order to improve the accuracy, 200 or more fillers may be measured and obtained.

Further, the embedding rate (Lb / D) can be collectively obtained for a certain number by adjusting the focus in the surface field image. Alternatively, a laser type discriminant displacement sensor (manufactured by KEYENCE, etc.) may be used for measuring the embedding rate (Lb / D).

(Aspects in which the embedding rate is 60% or more and less than 100%)
As a more specific embedding mode of the filler 1 having an embedding ratio (Lb / D) of 60% or more and 105% or less, first, as in the filler-containing film 10A shown in FIG. 1B, the filler 1 is formed from the resin layer 2. It is possible to give an embodiment in which the embedding rate is 60% or more and less than 100% so as to be exposed. In the filler-containing film 10A, the portion of the surface of the resin layer 2 in contact with the filler 1 exposed from the resin layer 2 and its vicinity thereof are in contact with the surface 2a of the resin layer in the central portion between the adjacent fillers. It has an inclination 2b recessed with respect to the plane 2p, and this recess forms a ridge line substantially along the outer shape of the filler.

Such an inclination 2b or an undulation 2c (FIGS. 4 and 6) determines the viscosity of the resin layer 2 when the filler 1 is pushed in when the filler-containing film is manufactured by pushing the filler 1 into the resin layer 2. The lower limit is preferably 3000 Pa · s or more, more preferably 4000 Pa · s or more, further preferably 4500 Pa · s or more, and the upper limit is preferably 20000 Pa · s or less, more preferably 15000 Pa · s or less, still more preferably 10000 Pa · s. It shall be s or less. Further, such a viscosity is preferably obtained at 40 to 80 ° C, more preferably 50 to 60 ° C.

(Aspect of 100% embedding rate)
Next, among the filler-containing films of the present invention, as an embodiment of the embedding rate (Lb / D) of 100%, the filler shown in FIG. 1B is surrounded by the filler 1 as in the filler-containing film 10B shown in FIG. Similar to the contained film 10A, the filler 1 has an inclination 2b forming a ridge line substantially along the outer shape of the filler, and the exposed diameter Lc of the filler 1 exposed from the resin layer 2 is smaller than the particle diameter D of the filler, FIG. 3A. As shown in FIG. 4, the inclination 2b around the exposed portion of the filler 1 suddenly appears in the vicinity of the filler 1, and the exposed diameter Lc of the filler 1 and the particle diameter D of the filler are substantially equal to each other, as shown in FIG. As shown in the filler-containing film 10D, the surface of the resin layer 2 has shallow undulations 2c, and the filler 1 is exposed from the resin layer 2 at one point on the top portion 1a.

In addition, a minute protruding portion 2q may be formed adjacent to the inclination 2b of the resin layer 2 around the exposed portion of the filler and the undulation 2c of the resin layer 2 directly above the filler. An example of this is shown in FIG. 3B, the filler-containing film 10C'.

Since the filler-containing films 10B, 10C, 10C', and 10D have an embedding rate of 100%, the top portion 1a of the filler 1 and the surface 2a of the resin layer 2 are flush with each other. When the top portion 1a of the filler 1 and the surface 2a of the resin layer 2 are flush with each other, the filler-containing film and the article are compared with the case where the filler 1 protrudes from the resin layer 2 as shown in FIG. 1B. There is an effect that the amount of resin in the film thickness direction is less likely to become non-uniform around each filler during thermal pressure bonding with the film, and the movement of the filler due to resin flow can be reduced. Even if the embedding rate is not strictly 100%, this effect can be obtained if the top of the filler 1 embedded in the resin layer 2 and the surface of the resin layer 2 are flush with each other. can. In other words, when the embedding ratio (Lb / D) is approximately 80 to 105%, particularly 90 to 100%, the top of the filler 1 embedded in the resin layer 2 and the surface of the resin layer 2 are flush with each other. However, the movement of the filler due to the resin flow can be reduced.

Among these filler-containing films 10B, 10C, 10C', and 10D, 10D is less likely to have a non-uniform amount of resin around the filler 1, so that the movement of the filler due to the resin flow can be eliminated, and it is one point on the top 1a. Since the filler 1 is exposed from the resin layer 2, the filler and the article can be easily bonded to each other, and when the filler-containing film is an anisotropic conductive film, the conductive particles 1 can be captured well at the terminals, and the conductive particles can be easily bonded. You can expect the effect that even a slight movement of the plastic is unlikely to occur. Therefore, this aspect is particularly effective when the fine pitch or the space between bumps is narrow.

The filler-containing films 10B (FIG. 2), 10C (FIG. 3A), and 10D (FIG. 4) having different shapes and depths of the inclination 2b and the undulations 2c are the resin layer 2 when the filler 1 is pushed in, as will be described later. It can be manufactured by changing the viscosity of the film.

(Aspects with an embedding rate of more than 100%)
Of the filler-containing films of the present invention, when the embedding rate exceeds 100%, the filler 1 is exposed as in the filler-containing film 10E shown in FIG. 5, and the resin layer 2 around the exposed portion is inclined with respect to the tangential plane 2p. Examples thereof include those having 2b and those having undulations 2c with respect to the tangent plane 2p on the surface of the resin layer 2 directly above the filler 1 as in the filler-containing film 10F shown in FIG.

The filler-containing film 10E (FIG. 5) having an inclination 2b in the resin layer 2 around the exposed portion of the filler 1 and the filler-containing film 10F (FIG. 6) having an undulation 2c in the resin layer 2 directly above the filler 1 are shown. It can be manufactured by changing the viscosity of the resin layer 2 when the filler 1 is pushed in when manufacturing them.

When the filler-containing film 10E shown in FIG. 5 is crimped to the article, the filler 1 is directly pressed from the article, so that the article and the filler can be easily bonded to each other. The catchability of conductive particles at the terminals is improved. Further, when the filler-containing film 10F shown in FIG. 6 is crimped with the article, the filler 1 does not directly press the article but presses it through the resin layer 2, but the amount of resin present in the pressing direction is shown in FIG. This is less than the state of 8 (that is, the filler 1 is embedded with an embedding rate of more than 100%, the filler 1 is not exposed from the resin layer 2, and the surface of the resin layer 2 is flat). , The filler is likely to be pressed. Therefore, when the filler-containing film is an anisotropic conductive film, it is prevented that the conductive particles 1 between the terminals move unnecessarily due to the resin flow at the time of anisotropic conductive connection.

The inclination 2b of the resin layer 2 around the exposed portion of the filler described above (FIG. 1B, FIG. 2, FIG. 3A, FIG. 3B, FIG. 5) and the undulation of the resin layer directly above the filler 2c (FIGS. 4 and 6). The ratio (Le / D) of the maximum depth Le of the inclination 2b around the exposed portion of the filler 1 to the particle diameter D of the filler 1 is preferably less than 50%, more preferably 30% from the viewpoint of facilitating the effect. Less than, more preferably 20 to 25%, and the ratio (Ld / D) of the maximum diameter Ld of the inclination 2b around the exposed portion of the filler 1 to the particle diameter D of the filler 1 is preferably 100% or more. It is preferably 100 to 150%, and the ratio (Lf / D) of the maximum depth Lf of the undulation 2c to the particle diameter D of the filler 1 in the resin directly above the filler 1 is larger than 0, preferably less than 10%. More preferably, it is 5% or less.

The exposed diameter (that is, the diameter of the exposed portion) Lc of the filler 1 can be equal to or less than the particle diameter D of the filler 1, preferably 10 to 90% of the particle diameter D of the filler 1. As shown in FIG. 4, it may be exposed at one point on the top of the filler 1, or the filler 1 may be completely buried in the resin layer 2 so that the exposed diameter Lc becomes zero.

On the other hand, the top of the filler 1 embedded in the resin layer 2 and the surface of the resin layer 2 are substantially flush with each other, and the depth of the dent due to the inclination 2b or the undulation 2c (from the tangent plane in the central portion between the adjacent fillers). When there is a region where a filler having a particle diameter of 10% or more (hereinafter, simply referred to as "a filler flush with the resin layer and having a dent depth of 10% or more") is locally concentrated. Even if there is no problem with the performance and quality of the filler-containing film, the appearance may be impaired. Further, when the filler-containing film and the article are bonded with the inclination 2b or the undulation 2c of such a region directed toward the article, the inclination 2b or 2c may cause floating or the like after the bonding. For example, when the filler-containing film is an anisotropic conductive film, conductive particles having a recess depth of 10% or more due to inclination or undulation on the insulating resin layer 2 are concentrated in one bump. Floating may occur after the connection, resulting in a decrease in conductivity. Therefore, in the region from any filler having a recess depth of 10% or more flush with the resin layer 2 within 200 times the particle diameter of the filler, the recess depth is 10 flush with the resin layer with respect to the total number of fillers. The ratio of the number of fillers of% or more is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. On the other hand, in the region where this ratio exceeds 50%, it is preferable to make the dent due to the inclination 2b or the undulation 2c shallow by spraying a resin on the surface of the filler-containing film. In this case, the resin to be sprayed preferably has a lower viscosity than the resin forming the resin layer 2, and the concentration of the resin to be sprayed is diluted to such an extent that a dent in the resin layer 2 can be confirmed after spraying. Is desirable. By making the dents due to the inclination 2b or the undulations 2c shallow in this way, the above-mentioned problems of appearance and floating can be improved.

As shown in FIG. 7, in the filler-containing film 10G having an embedding ratio (Lb / D) of less than 60%, the filler 1 easily rolls on the resin layer 2, and therefore, when the filler-containing film and the article are crimped together. In order to improve the connection state between the filler and the article, especially when the filler-containing film is an anisotropic conductive film, the embedding rate (Lb) is improved from the viewpoint of improving the capture rate at the time of anisotropic conductive connection. / D) is preferably 60% or more.

When the surface of the resin layer 2 is flat as in the filler-containing film 10X of the comparative example shown in FIG. 8 in an embodiment in which the embedding rate (Lb / D) exceeds 100%, the filler-containing film and the article are used. At the time of thermal crimping, the amount of resin interposed between the filler 1 and the terminal becomes excessively large, and the filler 1 does not directly press the article but presses the article through the resin layer. The filler is easily washed away by the resin flow.

In the present invention, the presence of the inclination 2b and the undulation 2c on the surface of the resin layer 2 can be confirmed by observing the cross section of the filler-containing film with a scanning electron microscope, and can also be confirmed by the surface field observation. It is possible to observe the inclination 2b and the undulation 2c with an optical microscope and a metallurgical microscope. Further, the magnitudes of the inclination 2b and the undulation 2c can be confirmed by adjusting the focus at the time of observing the image. Even after the inclination or undulation is reduced by heat pressing as described above, the remaining inclination or undulation can be confirmed by the same method as described above.

<Deformation mode of filler-containing film>
(Second resin layer)
The filler-containing film of the present invention has a lower melt viscosity than the resin layer 2 on the surface of the filler dispersion layer 3 on which the inclination 2b of the resin layer 2 is formed, as in the filler-containing film 10H shown in FIG. The second resin layer 4 having a low viscosity may be laminated. The second resin layer and the third resin layer described later are layers that do not contain the filler 1 dispersed in the filler dispersion layer. Further, as in the filler-containing film 10I shown in FIG. 10, a second resin layer 4 having a lower minimum melt viscosity than the resin layer 2 is formed on the surface of the resin layer 2 of the filler dispersion layer 3 on which the inclination 2b is not formed. It may be laminated. The same applies when the undulation 2c is formed instead of the inclination 2b.

The second resin layer 4 can also be made insulating or conductive depending on the use of the filler-containing film. By laminating the second resin layer 4, it is possible to improve the adhesiveness between two articles facing each other via the filler-containing film, and in particular, the filler-containing film can be attached to the second resin. An anisotropic conductive film having an insulating resin layer is used as a layer, and when electronic components are anisotropically conductively connected, the space formed by the electrodes and bumps of the electronic components is filled with a second resin layer, and the electronic components are connected to each other. Adhesiveness can be improved.

When the opposing articles are connected to each other by using the filler-containing film having the second resin layer 4, the second resin layer 4 has the second resin layer 4 regardless of whether or not the second resin layer 4 is on the forming surface of the inclined 2b. However, it is on the side of the article to be pressed by the thermocompression bonding tool, and when the filler-containing film is an anisotropic conductive film, it is on the side of the first electronic component such as an IC chip to be pressed by the thermocompression bonding tool (in other words). , The resin layer 2 is on the side of the second electronic component such as the substrate on which the stage is placed). By doing so, it is possible to avoid unintentional movement of the filler, and in the anisotropic conductive film, it is possible to improve the capture property of the conductive particles at the time of anisotropic conductive connection. The same applies even if the inclination 2b is an undulation 2c. When connecting the first electronic component and the second electronic component using an anisotropic conductive film, usually the first electronic component such as an IC chip is on the pressing jig side and the second electronic component such as a substrate is set as a stage. On the side, after the anisotropic conductive film is temporarily crimped to the second electronic component, the first electronic component and the second electronic component are mainly crimped, but it is different depending on the size of the thermal crimping region of the second electronic component. After the property conductive film is temporarily attached to the first electronic component, the first electronic component and the second electronic component are finally crimped.

The greater the difference in the minimum melt viscosity between the resin layer 2 and the second resin layer 4, the easier it is for the second resin layer 4 to fill the space between the two articles connected via the filler-containing film. Therefore, when the first electronic component and the second electronic component are anisotropically conductively connected, the space formed by the electrodes and bumps of the electronic component is easily filled with the second insulating resin layer 4, and the electronic component is easily filled. The effect of improving the adhesiveness between each other can be expected. Further, as this difference increases, the amount of movement of the insulating resin layer 2 holding the conductive particles in the conductive particle dispersion layer becomes relatively smaller than that of the second resin layer 4, so that the conductive particles are captured at the terminals. It becomes easier to improve the sex.

The minimum melt viscosity ratio between the resin layer 2 and the second resin layer 4 depends on the ratio of the layer thicknesses of the resin layer 2 and the second resin layer 4 in practice, but is preferably 2 or more, more preferably. It is 5 or more, more preferably 8 or more. On the other hand, if this ratio is too large, resin squeeze out or blocking may occur when a long filler-containing film is used as a wound body, so that the ratio is preferably 15 or less in practice. More specifically, the minimum melt viscosity of the second resin layer 4 satisfies the above ratio and is 3000 Pa · s or less, more preferably 2000 Pa · s or less, and particularly 100 to 2000 Pa · s.

The second resin layer 4 can be formed by adjusting the viscosity in the same resin composition as the resin layer 2.

The thickness of the second resin layer 4 can be appropriately set according to the use of the filler-containing film. From the viewpoint of not excessively increasing the difficulty of the laminating step of the second resin layer 4, it is generally preferable to set the particle size to 0.2 to 50 times the particle size of the filler. When the filler-containing film is an anisotropic conductive film 10H or 10I, the layer thickness of the second resin layer 4 is preferably 4 to 20 μm, and the conductive particle diameter is preferably 1 to 8. It is double.

Further, in the filler-containing films 10H and 10I, the layer thickness of the second resin layer 4 can be determined depending on the use of the filler-containing film, and is particularly limited because there are parts to be thermocompression-bonded and parts affected by thermocompression-bonding conditions. However, when the filler-containing film is an anisotropic conductive film, it is preferably 4 to 20 μm. Alternatively, it is preferably 1 to 8 times the diameter of the conductive particle.

Further, the minimum melt viscosity of the filler-containing film 10H and 10I in which the resin layer 2 and the second resin layer 4 are combined is determined by the use of the filler-containing film, the ratio of the thickness of the resin layer 2 and the second resin layer 4, and the like. However, when the filler-containing film is an anisotropic conductive film, it may be practically 8000 Pa · s or less, and 200 to 7000 Pa · s may be used to facilitate filling between bumps, preferably 200 to 7000 Pa · s. , 200-4000 Pa · s.

(Third resin layer)
In the filler-containing film of the present invention, a third resin layer may be provided on the opposite side of the second resin layer 4 and the resin layer 2. The third resin layer can also be made insulating or conductive depending on the use of the filler-containing film. For example, when the filler-containing film is an anisotropic conductive film having an insulating third resin layer, the third resin layer can function as a tack layer. When the filler-containing film is an anisotropic conductive film, the third resin layer may be provided to fill the space formed by the electrodes and bumps of the electronic component, similarly to the second resin layer.

The resin composition, viscosity and thickness of the third resin layer may be the same as or different from those of the second resin layer. The minimum melt viscosity of the filler-containing film obtained by combining the resin layer 2, the second resin layer 4, and the third resin layer is not particularly limited, but may be 8000 Pa · s or less, or 200 to 7000 Pa · s. Often, it can be set to 200 to 4000 Pa · s.

(Other stacking modes)
Depending on the use of the filler-containing film, a filler dispersion layer may be laminated, or a layer not containing a filler such as a second resin layer may be interposed between the laminated filler dispersion layers, and further, an outermost layer. A second resin layer or a third resin layer may be provided on the surface.

<Manufacturing method of filler-containing film>
The method for producing a filler-containing film of the present invention includes a step of forming a filler dispersion layer in which the filler is dispersed in the resin layer. The step of forming the filler dispersion layer includes a step of holding the filler on the surface of the resin layer at a specific area occupancy rate and a step of pushing the filler held in the resin layer into the resin layer.

Among these, in the step of holding the filler on the surface of the resin layer, the CV value of the particle size of the filler held on the surface of the resin layer is set to 20% or less. Further, the filler is held on the surface of the resin layer so that the filler is dispersed on the surface of the resin layer and the area occupancy of the filler calculated by the following equation is 0.3% or more.

Area occupancy (%) = [Number density of fillers in plan view] x [Average of area in plan view of one filler] x 100

On the other hand, in the step of pushing the filler held in the resin layer into the resin layer, the surface of the resin layer in the vicinity of the filler has an inclination or undulation with respect to the tangent plane of the resin layer in the central portion between the adjacent fillers. , The filler held on the surface of the resin layer is pushed into the resin layer.

The resin layer into which the filler is pushed is not particularly limited as long as it can form the undulations 2b or the inclination 2c of the previous operation, but it is preferable that the minimum melt viscosity is 1100 Pa · s or more and the viscosity at 60 ° C. is 3000 Pa · s or more. Above all, the minimum melt viscosity is preferably 1500 Pa · s or more, more preferably 2000 Pa · s or more, further preferably 3000 to 15000 Pa · s, particularly preferably 3000 to 10000 Pa · s, and the lower limit of the viscosity at 60 ° C. is It is preferably 3000 Pa · s or more, more preferably 4000 Pa · s or more, further preferably 4500 Pa · s or more, and the upper limit is preferably 20000 Pa · s or less, more preferably 15000 Pa · s or less, still more preferably 10000 Pa · s or less. Is.

When the filler-containing film is formed from a single layer of the filler dispersion layer 3, in the filler-containing film of the present invention, for example, the filler 1 is held on the surface of the resin layer 2 in a predetermined arrangement, and the filler 1 is flat or flat. Manufactured by pushing into the resin layer with a roller. When producing a filler-containing film having an embedding rate of more than 100%, the film may be pressed by a pressing plate having a convex portion corresponding to the arrangement of the filler.

Here, the amount of the filler 1 embedded in the resin layer 2 can be adjusted by the pressing pressure at the time of pressing the filler 1, the temperature, and the like. Further, the shape and depth of the inclination 2b and the undulation 2c are adjusted by the viscosity of the insulating resin layer 2 at the time of pushing, the pushing speed, the temperature and the like.

As a method for retaining the filler 1 in the resin layer 2, a known method can be used. For example, the filler 1 is directly sprayed on the resin layer 2, or the filler 1 is attached as a single layer to a film that can be biaxially stretched, the film is biaxially stretched, and the resin layer 2 is applied to the stretched film. By pressing and transferring the filler to the resin layer 2, the resin layer 2 holds the filler 1. Further, the filler 1 can be held in the resin layer 2 by filling the transfer mold with the filler and transferring the filler to the resin layer 2.

When the filler 1 is held in the resin layer 2 by using a transfer mold, the transfer mold may be used as an inorganic material such as a metal such as silicon, various ceramics, glass or stainless steel, or an organic material such as various resins. On the other hand, those in which the openings are formed by a known opening forming method such as a photolithograph method and those to which a printing method is applied can be used. Further, the transfer type can take a shape such as a plate shape or a roll shape. The present invention is not limited to the above method.

Further, a second resin layer having a viscosity lower than that of the resin layer can be laminated on the surface of the resin layer on which the filler is pressed or on the opposite surface thereof.

In order to economically crimp the filler-containing film to the article on an industrial production line, it is preferable to manufacture the filler-containing film to a certain length. Therefore, the filler-containing film is produced to have a length of preferably 5 m or more, more preferably 10 m or more, still more preferably 25 m or more. On the other hand, if the filler-containing film is made excessively long, it becomes difficult to use an existing crimping device, and the handleability is also inferior. Therefore, the filler-containing film is manufactured to have a length of preferably 5000 m or less, more preferably 1000 m or less, and further preferably 500 m or less. Further, it is preferable to use such a long filler-containing film as a wound body wound around a winding core from the viewpoint of excellent handleability.

<How to use the filler-containing film>
The filler-containing film of the present invention can be used by being bonded to an article in the same manner as the conventional filler-containing film, and the article is not particularly limited as long as the filler-containing film can be bonded to the article. The filler-containing film can be attached to various articles according to the intended use by thermocompression bonding, preferably thermocompression bonding. At the time of this bonding, light irradiation may be used, or heat and light may be used in combination. For example, when the resin layer of the filler-containing film has sufficient adhesiveness to the article to which the filler-containing film is attached, the filler-containing film can be used as one article by lightly pressing the resin layer of the filler-containing film against the article. A film-attached body attached to the surface can be obtained. In this case, the surface of the article is not limited to a flat surface, and may be uneven or may be bent as a whole. When the article is in the form of a film or a flat plate, the filler-containing film may be attached to the article using a pressure-bonding roller. Thereby, the filler of the filler-containing film and the article can be directly bonded.

Further, even if a filler-containing film is interposed between the first article and the second article facing each other and the two articles facing each other are joined by a thermocompression bonding roller or a crimping tool, the filler is sandwiched between the articles. good. Further, the filler-containing film may be sandwiched between the articles so that the filler and the article do not come into direct contact with each other.

When the filler-containing film is an anisotropic conductive film, the anisotropic conductive film is used with a first electronic component such as an IC chip, an IC module, or an FPC, and an FPC, a glass substrate, or a plastic substrate. , Can be used for anisotropic conductive connection with a second electronic component such as a rigid substrate or a ceramic substrate. IC chips and wafers may be stacked using the anisotropic conductive film of the present invention to form multiple layers. The electronic components connected by the anisotropic conductive film of the present invention are not limited to the above-mentioned electronic components. It can be used for various electronic components that have been diversified in recent years.

Therefore, the present invention includes a bonded body in which the filler-containing film of the present invention is bonded to various articles by thermocompression bonding, and a method for producing the bonded body. In particular, when the filler-containing film is used as an anisotropic conductive film, a method for manufacturing a connection structure for anisotropically conductively connecting the first electronic component and the second electronic component using the anisotropic conductive film, and a method thereof. The connection structure obtained by the above, that is, the connection structure in which the first electronic component and the second electronic component are anisotropically conductively connected by the anisotropic conductive film of the present invention is also included.

As a method of connecting electronic components using an anisotropic conductive film, when the anisotropic conductive film is composed of a single layer of the conductive particle dispersion layer 3, the anisotropic conductive film is attached to a second electronic component such as various substrates. The first electronic component such as an IC chip is temporarily attached from the side where the conductive particles 1 are embedded in the surface and temporarily pressure-bonded, and the conductive particles 1 of the anisotropic conductive film which is temporarily pressure-bonded are not embedded in the surface. It can be manufactured by combining and thermocompression bonding. When the insulating resin layer of the anisotropic conductive film contains not only the thermopolymerization initiator and the thermopolymerizable compound but also the photopolymerization initiator and the photopolymerizable compound (which may be the same as the thermopolymerizable compound). A crimping method using both light and heat may be used. In this way, the unintentional movement of the conductive particles can be minimized. Further, the side on which the conductive particles are not embedded may be temporarily attached to the second electronic component for use. It is also possible to temporarily attach the anisotropic conductive film to the first electronic component instead of the second electronic component.

When the anisotropic conductive film is formed of a laminate of the conductive particle dispersion layer 3 and the second insulating resin layer 4, the conductive particle dispersion layer 3 is temporarily attached to a second electronic component such as various substrates. Then, the temporary crimping is performed, and the first electronic component such as an IC chip is aligned and placed on the second insulating resin layer 4 side of the temporarily crimped anisotropic conductive film, and the heat crimping is performed. The second insulating resin layer 4 side of the anisotropic conductive film may be temporarily attached to the first electronic component. Further, the conductive particle dispersion layer 3 side can be temporarily attached to the first electronic component for use.

Hereinafter, the anisotropic conductive film, which is one aspect of the filler-containing film of the present invention, will be specifically described with reference to Examples.

Examples 1 to 11 and Comparative Examples 1 to 2.
(1) Production of Anisotropic Conductive Film A resin composition for forming an insulating resin layer and a second insulating resin layer was prepared with the formulations shown in Table 1, respectively.

The resin composition forming the insulating resin layer is applied on a PET film having a film thickness of 50 μm with a bar coater, dried in an oven at 80 ° C. for 5 minutes, and the insulating property having the thickness shown in Table 2 is shown on the PET film. A resin layer was formed. Similarly, a second insulating resin layer was formed on the PET film with the thickness shown in Table 2.

On the other hand, a mold is prepared so that the conductive particles 1 have a square lattice arrangement shown in FIG. 1A in a plan view, the distance between the particles is equal to the particle diameter of the conductive particles, and the number density of the conductive particles is 28,000 / mm ² . did. That is, the convex part pattern of the mold is a square lattice arrangement, the pitch of the convex parts on the lattice axis is twice the average conductive particle diameter (3 μm), and the lattice axis and the anisotropic conductive film are in the lateral direction (terminal). A mold having an angle θ formed with (longitudinal direction) of 15 ° is produced, and the pellets of known transparent resin are poured into the mold in a molten state, cooled and hardened, whereby the dent is shown in FIG. 1A. A resin mold of an arrangement pattern was formed.

Metal-coated resin particles (Sekisui Chemical Co., Ltd., AUL703, average particle diameter of 3 μm) are prepared as conductive particles, and the conductive particles are filled in a resin mold recess and covered with the above-mentioned insulating resin layer. , 60 ° C., 0.5 MPa to attach. Then, the insulating resin layer is peeled off from the mold, and the conductive particles on the insulating resin layer are pressed into the insulating resin layer by pressurizing (pressing conditions: 60 to 70 ° C., 0.5 MPa) to disperse the conductive particles. An anisotropic conductive film composed of a single layer was prepared (Examples 6 to 11 and Comparative Example 2). The state of embedding of conductive particles was controlled by pushing conditions. The CV value of the metal-coated resin particles used was 20% or less when measured with 1000 or more particles using FPIA-3000 (Malburn Co., Ltd.).

The area occupancy of the conductive particles in the anisotropic conductive film thus produced is
28,000 pieces / mm ² x (1.5 x 1.5 x 3.14 x 10 ^-6 ) x 100
= 19.8%.

Further, a two-layer type anisotropic conductive film was produced by laminating a second insulating resin layer on the similarly produced conductive particle dispersion layer (Examples 1 to 5 and Comparative Example 1).

(2) Embedded State The anisotropic conductive films of Examples 1 to 11 and Comparative Examples 1 and 2 were cut along a cutting line passing through the conductive particles, and the cross section thereof was observed with a metallurgical microscope. Further, with respect to Examples 4 to 11 and Comparative Example 2 in which the conductive particles are exposed on the surface of the anisotropic conductive film or the conductive particles are in the vicinity of the film surface of the anisotropic conductive film, the film surface thereof is measured with a metallurgical microscope. Observed. 11A shows a top photograph of Example 4, and FIG. 11B shows a top photograph of Example 8.

In Examples 1 to 6, 9 to 11 and Comparative Example 1, the conductive particles were exposed from the insulating resin layer. Of these, in Examples 1 to 6 and 9 to 11, an inclination 2b was observed on the surface of the insulating resin layer around the conductive particles, and the surrounding surface portion (the outer portion of the dotted line in FIG. 11A) was flat. Observed. On the other hand, in Comparative Example 1, no inclination was observed around the conductive particles.

In Example 8, the conductive particles are completely embedded in the insulating resin layer, and the conductive particles are not exposed from the insulating resin layer, but undulations 2c are observed on the surface of the insulating resin layer directly above the conductive particles. In addition, it was observed that the surrounding surface portion (the outer portion of the dotted line in FIG. 11B) was flat. In Comparative Example 2, the embedding rate was slightly larger than 100% and the conductive particles were not exposed from the resin layer, but the surface of the resin layer was flat and undulations were observed on the surface of the resin layer directly above the conductive particles. There wasn't.

The anisotropic conductive film of Example 7 is an example in which the inclination 2b of Example 6 and the undulation 2c of Example 8 are mixed. Inclined 2b was observed on the surface of the insulating resin layer around the conductive particles exposed from the insulating resin layer, and the surrounding surface portion was observed to be flat. On the other hand, undulations 2c were observed on the surface of the insulating resin layer directly above the conductive particles completely embedded in the insulating resin layer, and it was observed that the surrounding surface portion was flat.

(3) Evaluation With respect to the anisotropic conductive films of Examples and Comparative Examples produced in (1), (a) initial conduction resistance, (b) conduction reliability, and (c) particle capture property were determined as follows. Measured or evaluated. The results are shown in Table 2.

(A) Initial conduction resistance The anisotropic conductive films of each Example and Comparative Example are cut in an area sufficient for connection, sandwiched between the IC for evaluating conduction characteristics and the glass substrate, and heated and pressed (180 ° C.). , 60 MPa, 5 seconds) to obtain each evaluation connection, and the conduction resistance of the obtained evaluation connection was measured by the 4-terminal method. Practically, the initial conduction resistance is preferably B evaluation or higher, and more preferably A evaluation. Even if it is C evaluation, there is no practical problem if it is 2Ω or less.

Here, the evaluation IC and the glass substrate correspond to their terminal patterns, and the sizes are as follows. Further, when connecting the evaluation IC and the glass substrate, the longitudinal direction of the anisotropic conductive film and the lateral direction of the bump were aligned.

IC for evaluating conduction characteristics
External shape 1.8 x 20.0 mm
Thickness 0.5 mm
Bump specifications Size 30 x 85 μm, distance between bumps 50 μm, bump height 15 μm

Glass substrate (ITO wiring)
Glass material Corning 1737F
External shape 30 x 50 mm
Thickness 0.5 mm
Electrode ITO wiring

Initial conduction resistance evaluation standard A Less than 0.3Ω B More than 0.3Ω Less than 1Ω C 1Ω or more

(B) Conduction reliability The conduction resistance of the evaluation connection produced in (a) after being placed in a constant temperature bath at a temperature of 85 ° C. and a humidity of 85% RH for 500 hours was measured in the same manner as the initial conduction resistance. Practically, the continuity reliability is preferable if it is evaluated as B or higher, and even more preferably if it is evaluated as A. Even if it is C evaluation, there is no practical problem if it is 6Ω or less.

Conduction reliability evaluation criteria A 2.5 Ω or less B 2.5 Ω or more and less than 5 Ω C 5 Ω or more

(C) Particle capture property An IC for evaluation of particle capture property is used, and the evaluation IC and the glass substrate (ITO wiring) corresponding to the terminal pattern are heated and pressed (180 ° C., 60 MPa) with the alignment shifted by 6 μm. 5 seconds), the number of captured conductive particles was measured for 100 particles in the area of 6 μm × 66.6 μm where the bumps of the evaluation IC and the terminals of the substrate overlap, and the minimum number of captured particles was obtained and evaluated according to the following criteria. .. Practically, it is preferable that the evaluation is B or higher.

IC for evaluating particle capture
External shape 1.6 x 29.8 mm
Thickness 0.3mm
Bump specifications Size 12 x 66.6 μm, bump pitch 22 μm (L / S = 12 μm / 10 μm), bump height 12 μm

Particle capture evaluation criteria A 5 or more B 3 or more and less than 5 C Less than 3

From Table 2, Examples 1 to 7 and 9 in which the embedding rate of the conductive particles is between 60 and 105%, the conductive particles are exposed from the insulating resin layer and have an inclination of 2b, and the conductive particles are insulating. In Example 8 which is completely buried in the resin layer and has undulations 2c, both the initial conduction resistance and the conduction reliability are evaluated as A, and the evaluation of the particle trapping property is also good, but the embedding rate is in this range. Comparative Example 1 in which the conductive particles are exposed from the insulating resin layer but have no inclination 2b, and Comparative Example 2 in which the embedding rate is approximately 100% and the conductive particles are completely embedded in the insulating resin layer and there is no undulation 2c. It can be seen that the particle capture property is evaluated as C, and the conductive particles cannot be retained at the time of connection, so that fine pitch connection cannot be supported. From this, if the surface of the insulating resin layer 2 is raised along the shape of the conductive particles 1, the conductive particles are easily affected by the resin flow at the time of anisotropic conductive connection, and the conductive particles are attached to the terminals. It can be inferred that the push is insufficient.

Further, in Examples 1 to 7 and 9 described above, the minimum melt viscosity of the insulating resin layer is 2000 Pa · s or more and the melt viscosity at 60 ° C. is 3000 Pa · s or more, while in Comparative Examples 1 and 2, the minimum melt viscosity is 1000 Pa · s or more. It can be seen that the melt viscosity at 60 ° C. was 1500 Pa · s, and the inclination 2b and the undulation 2c were not formed because the viscosity at the time of pushing was lowered by adjusting the pushing conditions of the conductive particles.

From Examples 4 and 5 and Examples 6 and 9, when the anisotropic conductive film is a two-layer type of a conductive particle dispersion layer and a second insulating resin layer, or when it is a single layer of the conductive particle dispersion layer. However, it can be seen that the evaluation of particle trapping property is practically good.

From Examples 3 and 4 and 5, when the anisotropic conductive film is a two-layer type of a conductive particle dispersion layer and a second insulating resin layer, the conductive particles of the insulating resin layer are pushed into the surface. It can be seen that the evaluation of the particle trapping property is practically good both when the second insulating resin layer is laminated and when the second insulating resin layer is laminated on the opposite side thereof.

The same resin composition diluted by spraying the same resin composition diluted on the surface of the anisotropic conductive film of Examples 4 and 5 on which the conductive particles were exposed was sprayed, and the surface thereof was substantially flattened, and the same evaluation was performed. , Approximately equivalent results were obtained.

In the evaluation products for which the initial continuity of all the examples was measured, the number of shorts in 100 bumps was confirmed in the same manner as the method for measuring the number of shorts described in the examples of JP-A-2016-085983. Nothing was short-circuited. Further, when the short-circuit occurrence rate was determined according to the method for measuring the short-circuit occurrence rate of the examples described in JP-A-2016-085982 for the anisotropic conductive films of all the examples, all of them were less than 50 ppm and were practically used. I confirmed that there was no problem. In the case of an anisotropic conductive film in which conductive particles are kneaded in an insulating resin and randomly dispersed, the short-circuit occurrence rate is larger than this. This can be confirmed by referring to Comparative Example 2 of Patent Document 2, Comparative Example 2 of Patent Document 3, and the like.

The anisotropic conductive film of Example 7 in which the inclination and the undulation were mixed obtained the same results as those of Examples 6 and 8. From this, it can be seen that the effect is exhibited by the presence of the inclination or undulation in the vicinity of the conductive particles. Further, the fact that the same effect was obtained in Examples 6 to 8 indicates that a wide margin can be obtained under the manufacturing conditions of the anisotropic conductive film. This is expected to have various effects such as reduction of manufacturing cost of anisotropic conductive film and speeding up of design change, and has great industrial merit.

Experimental Examples 1 to 4
(Manufacturing anisotropic conductive film)
For the anisotropic conductive film used for COG connection, in order to investigate the effect of the resin composition of the insulating resin layer on the film forming ability and conduction characteristics, the insulating resin layer and the second insulating property were formulated according to Table 3. A resin composition for forming a resin layer was prepared. In this case, the minimum melt viscosity of the resin composition was adjusted according to the preparation conditions of the insulating resin composition. Using the obtained resin composition, an insulating resin layer is formed in the same manner as in Example 1, and by pushing conductive particles into the insulating resin layer, an anisotropic composition of a single layer of the conductive particle dispersion layer is formed. A conductive film was prepared, and a second insulating resin layer was laminated on the side where the conductive particles of the insulating resin layer were pushed to prepare an anisotropic conductive film shown in Table 4. In this case, the arrangement of the conductive particles is the same as that of the first embodiment. Further, by appropriately adjusting the pushing conditions of the conductive particles, the conductive particles were in the embedded state shown in Table 4.

In the process of producing this anisotropic conductive film, the film shape was not maintained in Experimental Example 4 after the conductive particles were pushed into the insulating resin layer (film shape evaluation: NG), but in the other experimental examples, the film shape was not maintained. Was maintained (film shape evaluation: OK). Therefore, the anisotropic conductive film of the experimental examples excluding Experimental Example 4 was measured by observing the embedded state of the conductive particles with a metallurgical microscope, and further evaluation was performed thereafter.

In each experimental example except Experimental Example 4, tilt or both tilt and undulation were observed, but Table 4 shows the measured values of the one in which the tilt was most clearly observed in each experimental example. The observed implantation condition satisfied the above-mentioned preferable range.

(evaluation)
(A) Initial conduction resistance and conduction reliability The initial conduction resistance and conduction reliability were evaluated in three stages in the same manner as in Example 1. The evaluation criteria in this case are the same as in Example 1. The results are shown in Table 4.

(B) Particle capture property The particle capture property was evaluated in the same manner as in Example 1.
As a result, all of Experimental Examples 1 to 3 were B-judgment or higher.

(C) Short-circuit occurrence rate The short-circuit occurrence rate was evaluated in the same manner as in Example 1.
As a result, it was confirmed that all of Experimental Examples 1 to 3 were less than 50 ppm and there was no practical problem.

From Table 4, it can be seen that when the minimum melt viscosity of the insulating resin layer is 1000 Pa · s or less, it is difficult to form a film in which the insulating resin layer in the vicinity of the conductive particles has an inclination. On the other hand, when the minimum melt viscosity of the insulating resin layer is 1500 Pa · s or more, it is possible to form an inclination on the surface of the insulating resin layer in the vicinity of the conductive particles by adjusting the conditions at the time of embedding the conductive particles. It can be seen that the anisotropic conductive film has good conduction characteristics for COG.

Experimental Examples 5-8
(Manufacturing anisotropic conductive film)
For the anisotropic conductive film used for FOG connection, in order to investigate the effect of the resin composition of the insulating resin layer on the film forming ability and conduction characteristics, the insulating resin layer and the second insulating property were formulated according to Table 5. A resin composition for forming a resin layer was prepared. In this case, the arrangement of the conductive particles was a hexagonal lattice arrangement with a number density of 15,000 / mm ² , and one of the lattice axes was tilted by 15 ° with respect to the longitudinal direction of the anisotropic conductive film. Further, the minimum melt viscosity of the resin composition was adjusted according to the preparation conditions of the insulating resin composition. Using the obtained resin composition, an insulating resin layer is formed in the same manner as in Example 1, and by pushing conductive particles into the insulating resin layer, an anisotropic composition of a single layer of the conductive particle dispersion layer is formed. A conductive film was prepared, and a second insulating resin layer was laminated on the side where the conductive particles of the insulating resin layer were pushed to prepare an anisotropic conductive film shown in Table 6. In this case, by appropriately adjusting the pushing conditions of the conductive particles, the conductive particles were in the embedded state shown in Table 6.

In the process of producing this anisotropic conductive film, the film shape was not maintained in Experimental Example 8 after the conductive particles were pushed into the insulating resin layer (film shape evaluation: NG), but in the other experimental examples, the film shape was not maintained. Was maintained (film shape evaluation: OK). Therefore, the anisotropic conductive film of the experimental examples excluding Experimental Example 8 was measured by observing the embedded state of the conductive particles with a metallurgical microscope, and further evaluation was performed thereafter.

In addition, although the inclination or both the inclination and the undulation were observed in each experimental example except the experimental example 8, Table 6 shows the measured values of the one in which the inclination was most clearly observed in each experimental example. .. The observed implantation condition satisfied the above-mentioned preferable range.

(evaluation)
(A) Initial conduction resistance and continuity reliability (i) Initial conduction resistance and (ii) Conduction reliability were evaluated as follows. The results are shown in Table 6.

(I) Initial conduction resistance The anisotropic conductive film obtained in each experimental example is cut with an area sufficient for connection, sandwiched between the FPC for evaluating conduction characteristics and a non-alkali glass substrate, and the tool width of the thermocompression bonding tool. Heating and pressurization (180 ° C., 4.5 MPa, 5 seconds) was performed at 1.5 mm to obtain each evaluation connection. The conduction resistance of the obtained evaluation connection was measured by the 4-terminal method, and the measured value was evaluated according to the following criteria.

FPC for evaluation of continuity characteristics:
Terminal pitch 20 μm
Terminal width / Space between terminals 8.5 μm / 11.5 μm
Polyimide film thickness (PI) / copper foil thickness (Cu) = 38/8, Sn plating

Non-alkali glass substrate:
Electrode ITO wiring thickness 0.7mm

Evaluation criteria for initial conduction resistance OK: Less than 2.0Ω NG: 2.0Ω or more

(Ii) Conduction reliability The evaluation connection made in (i) is placed in a constant temperature bath at a temperature of 85 ° C. and a humidity of 85% RH for 500 hours, and the subsequent conduction resistance is measured in the same manner as the initial conduction resistance, and the measurement thereof is performed. The values were evaluated according to the following criteria.

Evaluation criteria for continuity reliability OK: Less than 5.0Ω NG: 5.0Ω or more

(B) Particle trapping property The number of conductive particles captured was measured for 100 terminals of the evaluation connection made in (i), and the minimum number of captured particles was determined. If the minimum number of captures is 10 or more, there is no practical problem.
In each of Experimental Examples 5 to 7, the minimum number of captures was 10 or more.

(C) Short-circuit occurrence rate The number of short-circuits of the evaluation connection made in (i) was measured, and the short-circuit occurrence rate was obtained from the measured number of shorts and the number of gaps of the evaluation connection. It was confirmed that the short-circuit occurrence rate was less than 50 ppm in each of Experimental Examples 5 to 7, and there was no practical problem.

From Table 6, it can be seen that when the minimum melt viscosity of the insulating resin layer is 1000 Pa · s or less, it is difficult to form a film having an inclination on the surface of the insulating resin layer in the vicinity of the conductive particles. On the other hand, when the minimum melt viscosity of the insulating resin layer is 1500 Pa · s or more, it is possible to form an inclination on the surface of the insulating resin layer in the vicinity of the conductive particles by adjusting the conditions at the time of embedding the conductive particles. It can be seen that the anisotropic conductive film has good conduction characteristics for FOG.

1 Filler, conductive particles 1a Top of filler 2 Resin layer, insulating resin layer 2a Surface of resin layer 2b Inclined 2c Undulating 2f Flat surface part 2p Contact plane 2q Protruding part 3 Filler dispersion layer, Conductive particle dispersion layer 4 Second Resin layer, second insulating resin layer 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I Filler-containing film, anisotropic conductive film 20 terminals of Examples A lattice axis D conductive particle diameter, filler Particle size La Resin layer layer thickness Lb embedding amount (distance of the deepest part of the conductive particles from the tangent plane in the central part between adjacent conductive particles)
Lc Exposure diameter Ld Maximum diameter of inclination Le Maximum depth of inclination Lf Maximum depth of undulation θ The angle between the longitudinal direction of the terminal and the lattice axis of the array of conductive particles.

Claims (24)

A filler-containing film having a filler dispersion layer in which the filler is dispersed in the resin layer.
The surface of the resin layer in the vicinity of the filler has an inclination or undulation with respect to the tangent plane of the resin layer in the central portion between the adjacent fillers.
In the slope, the surface of the resin layer around the filler is chipped with respect to the tangent plane.
In the undulation, the amount of resin in the resin layer directly above the filler is smaller than that when the surface of the resin layer directly above the filler is on the tangent plane.
The CV value of the particle size of the filler is 20% or less,
Area occupancy rate of filler calculated by the following equation Area occupancy rate (%) = [Number density of fillers in plan view] x [Average of plane view area of one filler] x 100
Filler-containing film with a content of 0.3% or more. The filler-containing film according to claim 1, wherein the ratio (Lb / D) of the deepest distance Lb of the filler from the tangential plane to the particle size D of the filler is 60% or more and 105% or less. The filler-containing film according to claim 1 or 2, wherein the filler is exposed from the resin layer. The filler-containing film according to claim 1 or 2, wherein the filler is embedded in the resin layer without being exposed from the resin layer. The filler-containing film according to any one of claims 1 to 4, wherein the ratio (Le / D) of the depth Le of the inclination or undulation from the tangent plane to the particle size D of the filler is less than 50%. The filler-containing film according to any one of claims 1 to 5, wherein the ratio (Ld / D) of the maximum diameter Ld of the inclination or undulation to the particle size D of the filler is 100% or more. The filler-containing film according to any one of claims 1 to 6, wherein the ratio (La / D) of the layer thickness La of the resin layer to the particle size D of the filler is 0.6 to 10. The filler-containing film according to any one of claims 1 to 7, wherein the fillers are arranged in a non-contact manner with each other. The filler-containing film according to any one of claims 1 to 8, wherein the distance between the closest fillers is 0.5 times or more the particle size of the filler. The filler-containing film according to any one of claims 1 to 9, wherein the second resin layer is laminated on the surface opposite to the surface on which the slope or undulation of the resin layer of the filler dispersion layer is formed. The filler-containing film according to any one of claims 1 to 9, wherein a second resin layer is laminated on a surface on which an inclination or undulation of the resin layer of the filler dispersion layer is formed. The filler-containing film according to claim 10 or 11, wherein the minimum melt viscosity of the second resin layer is lower than the minimum melt viscosity of the resin layer of the filler dispersion layer. The filler-containing film according to any one of claims 1 to 12, wherein the resin layer of the filler dispersion layer has a viscosity of more than 1100 Pa · s at 60 ° C. The filler-containing film according to any one of claims 1 to 13, wherein the filler is conductive particles and the resin layer of the filler dispersion layer is an insulating resin layer, which is used as an anisotropic conductive film. A film-attached body to which the filler-containing film according to any one of claims 1 to 14 is attached to an article. A connection structure in which a first article and a second article are connected via the filler-containing film according to any one of claims 1 to 14. A connection structure in which the first electronic component and the second electronic component are anisotropically conductively connected via the filler-containing film according to claim 14 . A method for manufacturing a connection structure in which a first article and a second article are pressure-bonded via the filler-containing film according to any one of claims 1 to 14. By thermocompression bonding the first electronic component and the second electronic component via the filler-containing film according to claim 14 , the first electronic component and the second electronic component are anisotropically conductively connected to manufacture a connection structure. How to manufacture a connection structure. A method for producing a filler-containing film, which comprises a step of forming a filler dispersion layer in which a filler is dispersed in a resin layer.
The steps of forming the filler dispersion layer include a step of retaining a filler having a particle size CV value of 20% or less on the surface of the resin layer.
It has a step of pushing the filler held on the surface of the resin layer into the resin layer.
In the step of holding the filler on the surface of the resin layer, the filler is dispersed on the surface of the resin layer, and the area occupancy rate of the filler calculated by the following equation on the surface of the resin layer = [plan view]. [Number density of fillers in] x [Average plane area of one filler] x 100
Is 0.3% or more
In the step of pushing the filler into the resin layer, the surface of the resin layer in the vicinity of the filler has an inclination or undulation with respect to the tangent plane of the resin layer in the central portion between the adjacent fillers, and in the inclination, the resin layer around the filler. The surface of the resin layer is chipped with respect to the tangent plane, and the amount of resin in the resin layer directly above the filler is smaller in the undulations than when the surface of the resin layer directly above the filler is in the tangent plane. A method for producing a filler-containing film that adjusts the viscosity, pressing speed, or temperature of the resin layer when the filler is pushed. In the step of pushing the filler into the resin layer, when the filler is pushed so that the ratio (Lb / D) of the distance Lb of the deepest part of the filler from the tangent plane to the particle diameter D of the filler is 60% or more and 105% or less. The method for producing a filler-containing film according to claim 20 , wherein the pressing force, the viscosity of the resin layer, the pressing speed, or the temperature is adjusted. In the step of holding the filler on the surface of the resin layer, the filler is held on the surface of the resin layer in a predetermined arrangement.
The method for producing a filler-containing film according to claim 20 or 21 , wherein in the step of pushing the filler into the resin layer, the filler is pushed into the resin layer with a flat plate or a roller. Any of claims 20 to 22 in the step of holding the filler on the surface of the resin layer, the transfer mold is filled with the filler, and the filler is transferred to the resin layer to hold the filler on the surface of the resin layer in a predetermined arrangement. The method for producing a filler-containing film according to the above. The invention according to any one of claims 20 to 23 , wherein in order to use the filler-containing film as an anisotropic conductive film, conductive particles are used as the filler and an insulating resin layer is used as the resin layer of the filler dispersion layer. A method for producing a filler-containing film.

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