JP7319578B2 - Filler containing film - Google Patents

Description

The present invention relates to filler-containing films.

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

On the other hand, in order to reduce the short circuit and improve the workability when the anisotropic conductive film is temporarily pressure-bonded to the substrate, a photocurable resin layer in which conductive particles are embedded in a single layer and an insulating adhesive layer. has been proposed (Patent Document 5). As a method for 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 fix the conductive particles, After that, the substrate and the electronic component are finally pressure-bonded.

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

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

However, in the anisotropic conductive film described in Patent Document 5, the conductive particles are likely 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 a 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 together, the electronic component There is a problem that the conductive particles are difficult to be captured at the ends of the bumps, and a problem that an excessively large force is required to push the conductive particles and the conductive particles cannot be pushed sufficiently. Further, in Patent Document 5, in order to improve the pressing of the conductive particles, sufficient studies are not made from the viewpoint of exposure of the conductive particles from the photocurable resin layer.

Therefore, instead of the photocurable resin layer, conductive particles are dispersed in an insulating resin layer that becomes highly viscous at the heating temperature during anisotropic conductive connection, suppressing the fluidity of the conductive particles during anisotropic conductive connection. In addition, it is conceivable to improve the workability when attaching the anisotropic conductive film to the electronic component. However, even if the conductive particles are precisely arranged in such an insulating resin layer, when the resin layer flows during anisotropic conductive connection, the conductive particles also flow at the same time. It is difficult to sufficiently reduce short circuits, and it is also difficult to maintain the original precise arrangement of the conductive particles after the anisotropic conductive connection, and to keep the conductive particles separated from each other.

In addition, in the case of the three-layered anisotropic conductive film described in Patent Documents 6 and 7, although there is no problem with the basic anisotropic conductive connection characteristics, the three-layered structure reduces the manufacturing cost. From this point of view, it is required to reduce the number of manufacturing man-hours. In addition, in the vicinity of the conductive particles on one side of the first connection layer, the whole or part of the first connection layer is greatly raised along the outer shape of the conductive particles, and the insulating resin layer itself forming the first connection layer is flat. However, since the conductive particles are held in the protruded portion, there is concern that there will be many design restrictions in order to improve the retention of the conductive particles and the catching property of the terminals.

In contrast, the present invention provides filler-containing films such as anisotropic conductive films, even if a three-layer structure is not essential, and a resin holding filler such as conductive particles in the vicinity of the filler. To suppress unnecessary movement of filler due to flow of a resin layer during thermocompression bonding of a filler-containing film without making the whole or part of the resin layer protrude larger than the outer shape of the filler, in particular, to prevent the filler-containing film from being different. When configured as an anisotropic conductive film, it is an object to improve the ability to capture conductive particles and to reduce short circuits.

The present inventors have obtained the following findings regarding the relationship between the surface shape of the resin layer near the filler and the viscosity of the resin layer, regarding a filler-containing film having a filler-dispersed layer in which a filler such as conductive particles is 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 tangential plane of the resin layer in the central portion between the adjacent fillers. , the surface of the resin layer is partially chipped, and as a result, when the filler-containing film is thermocompression bonded to the article to bond the filler to the article, there is a risk of hindering the bonding of the filler and the article. (ii) When the filler is buried in the resin layer without being exposed from the resin layer, the resin layer in the center between the adjacent fillers is added to the resin layer directly above the filler. If a minute undulation (hereinafter simply referred to as undulation), which is recognized as a trace of embedding the filler, is formed on the tangential plane of the As a result, when the filler-containing film is crimped to the article, the filler is easily pushed into the article; Good connection between the sandwiched filler and the article, in other words, improvement of the catching property of the filler in the article, or improvement in consistency of the placement state of the filler sandwiched by the article before and after crimping, and further, the filler-containing film. We have found that it facilitates product inspection and usage confirmation. In addition, it was found that such depressions in the resin layer can be formed by adjusting the viscosity of the resin layer into which the filler is pushed when forming the filler-dispersed layer 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-dispersed 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 undulations with respect to the tangential plane of the resin layer in the central portion between adjacent fillers,
In the inclination, the surface of the resin layer around the filler is lacking with respect to the tangential plane,
In the undulations, the amount of resin in the resin layer directly above the filler is smaller than when the surface of the resin layer directly above the filler is on the tangential plane,
The CV value of the particle size of the filler is 20% or less,
Filler Area Occupancy Area Area Occupancy (%) = [number density of filler in plan view] x [average area of one filler in plan view] x 100
is 0.3% or more.

The present invention also provides a method for producing a filler-containing film, comprising a step of forming a filler-dispersed layer in which a filler is dispersed in a resin layer,
The step of forming a filler dispersed layer is a step of holding a filler having a particle size CV value of 20% or less on the surface of the resin layer;
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 resin layer surface, the filler is dispersed on the resin layer surface, and the area occupation ratio of the filler on the resin layer surface calculated by the following formula Area occupation ratio (%) = [in plan view Filler number density] × [average planar view area of one filler] × 100
is 0.3% or more,
In the step of pressing the filler into the resin layer, the surface of the resin layer in the vicinity of the filler has an inclination or undulations with respect to the tangential plane of the resin layer in the central portion between the adjacent fillers, and the inclination is such that the resin layer around the filler The surface of is chipped with respect to the tangential plane, and in the undulations, the amount of resin in the resin layer directly above the filler is less than when the surface of the resin layer directly above the filler is on the tangential plane. Provided is a method for producing a filler-containing film that adjusts the viscosity, pushing speed or temperature of a resin layer when the filler is pushed.

The filler-containing film of the present invention has a filler-dispersed 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-dispersed layer in the vicinity of the filler is inclined so as to be recessed with respect to the tangential plane of the resin layer in the central portion between adjacent fillers, or It 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 slanted, and the filler is buried in the resin layer without being exposed from the resin layer. If there is, there are undulations in the resin layer directly above the filler. In addition, undulations may exist even when the filler embedded in the resin layer is in contact with the surface of the resin layer at one point.

The slopes and undulations are 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 pressing the filler into the resin layer. Therefore, in the vicinity of the filler, depending on the degree of embedding, when the entire filler is embedded in the resin layer and the resin of the resin layer exists directly above the filler (for example, see FIGS. 4 and 6), or when the filler is buried. In some cases, the top portion is exposed from the resin layer, and the resin layer near the filler is dragged by the filler embedding and penetrates inside (see, for example, FIGS. 1B and 2). exist. In terms of formation mechanism, the slope is a slope formed around the filler when the resin layer in the vicinity of the filler is dragged by the filling of the filler and penetrates inside. Further, the undulations are undulations formed directly above the conductive particles as traces of the embedding of the filler when the entire filler is embedded in the resin layer.

Thus, slopes and undulations are formed when filler is forced into a resin layer of relatively high viscosity, so the presence of slopes or undulations in a resin layer means that the resin layer is capable of forming slopes or undulations. It means that it has a high viscosity that When the resin layer has a high viscosity, unnecessary resin flow is suppressed when the filler-containing film is thermocompression bonded to an article, and it is possible to suppress the filler from flowing out due to the resin flow. Furthermore, since the resin that interferes with the bonding between the filler and the article during thermocompression bonding does not exist or is reduced, the resin layer interferes with bonding between the article and the filler even if the resin layer has a high viscosity. never.

In addition, when the resin layer is formed of a high-viscosity resin that enables the formation of slopes or undulations, the thickness of the resin layer itself is reduced, and the thickness of the resin layer and the second layer having a low viscosity compared to the resin layer are reduced. By laminating the second resin layer, it is possible to maintain the adhesive performance of the filler-containing film when the filler-containing film is thermocompression bonded to the article, and to suppress unnecessary flow of the filler during thermocompression bonding. Reducing the thickness of the resin layer also brings about the effect of making it easier to secure a margin for the heating and pressurizing conditions of the connecting tool. Such an effect is exhibited more remarkably when the variation in 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 effects can be sufficiently exhibited.

In addition, since the slopes and undulations of the resin layer exist in the vicinity of the filler, it is possible to easily determine the quality of the filler dispersion state by observing the appearance of the filler-containing film during production of the filler-containing film. .

When the resin layer has the above-described slopes and undulations, unnecessary flow of the resin layer can be reduced when the filler-containing film is crimped from the filler side of the filler-containing film onto an article to which the filler-containing film is to be adhered. effect is also obtained. Therefore, for example, when the filler-containing film is configured as an anisotropic conductive film, an unnecessary resin is used for anisotropic conductive connection in which the first electronic component and the second electronic component are thermocompression bonded via the anisotropic conductive film. The effect of flow can be minimized, and the ability to trap conductive particles during anisotropic conductive connection is improved.

In addition, due to the inclination, the amount of resin near the filler is reduced by the amount of the inclination and undulations, compared to 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. Furthermore, when two articles are pressure-bonded with the filler-containing film interposed therebetween, the resin is less likely to interfere with the sandwiching of the filler or the flattening of the filler. In addition, since the amount of resin around the filler is reduced due to the inclination, resin flow that leads to unnecessary flow of the filler is reduced. Therefore, the scavenging property of the filler in the article is improved. In particular, when the filler-containing film is configured as an anisotropic conductive film, the scavenging property of the conductive particles in the terminal is improved, thereby improving the conduction reliability.

When the insulating resin layer directly above the conductive particles embedded in the insulating resin layer has undulations, similarly to the case where there is a slope, the pressing force from the terminal is likely to be applied to the conductive particles during anisotropic connection. . This is because the amount of resin directly above the conductive particles is reduced due to depressions accompanying undulations. Therefore, compared to the case where the resin is evenly deposited directly above the conductive particles (see FIG. 8), the conductive particles can be captured more effectively at the terminal, and the reliability of conduction is improved.

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 an article to which the filler-containing film is adhered, thereby suppressing unnecessary flow of the filler. It is possible to 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 anisotropic conductive film is used to connect the first electronic component and the second electronic component, the conductive particles on the terminals are less likely to flow. Therefore, the trapping property of the conductive particles is improved, and the arrangement of the conductive particles during 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 terminal space 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 (out of the width of a pair of terminals facing each other during connection, the width of the overlapping portion in plan view) ) is 3 μm or more and the shortest distance between terminals is 3 μm or more, electronic parts can be connected without causing a short circuit.

In addition, since the arrangement of the 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 can be changed according to the terminals of various electronic parts. It is possible to correspond to the layout of

Furthermore, in the filler-containing film of the present invention, if the resin layer directly above the filler embedded in the resin layer has the dents due to the above-described undulations, the position of the filler can be clearly identified by observing the appearance of the filler-containing film. This makes it easy to inspect the product by using the camera, and also makes it easy to identify the front and back of the film surface. Therefore, when the filler-containing film is pressure-bonded to the article, it is easy to confirm which side of the filler-containing film is to be attached to the article. Similar advantages are obtained when producing filler-containing films.

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 placement of the filler. can have tackiness. Therefore, the workability is improved when the filler-containing film and the article are temporarily pressure-bonded, and the workability is also improved when the second article is further pressure-bonded after the temporary pressure-bonding.

On the other hand, according to the method for producing a filler-containing film of the present invention, the viscosity and the like of the resin layer when the filler is embedded in the resin layer are adjusted so that the above-described slopes or undulations are formed in the resin layer. Therefore, the filler-containing film of the present invention that exhibits the above effects can be easily produced.

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

An example of the filler-containing film of the present invention will be described in detail below with reference to the drawings. In addition, in each figure, the same code|symbol represents the same or equivalent component.

<Overall structure of filler-containing film>
FIG. 1A is a plan view for explaining the particle arrangement of a filler-containing film 10A of one example of the present invention, and FIG. 1B is its XX cross-sectional view. This filler-containing film 10A is used as an anisotropic conductive film, and is obtained by dispersing conductive particles as a filler 1 in an insulating resin layer 2 .

This filler-containing film 10A can be in the form of a long film having a length of 5 m or longer, for example, and can be a wound body wound around a winding core.

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

In the vicinity of each filler 1, the surface 2a of the resin layer 2 around the filler 1 is formed with an inclination 2b with respect to the tangential 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, the term “inclination” refers to 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 portion of the resin layer is missing with respect to the tangential plane 2p, resulting in a decrease in the amount of resin. means On the other hand, "undulation" means a state in which the surface of the resin layer directly above the conductive particles is undulated, and the resin is reduced due to the presence of concave portions accompanying the undulations. These are recognized by contrasting the portion corresponding to directly above the filler and the flat surface portion between the fillers (2f in FIGS. 1B, 4, and 6; outside 2b in FIG. 11A and outside 2c in FIG. 11B). be able to. Note that the undulation starting point may exist as an inclination.

<Filler dispersion state>
The dispersed state of the filler in the present invention includes both 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 terms of suppressing unnecessary flow of the filler when the filler-containing film is thermocompression bonded to the article to be adhered with the filler-containing film, particularly When the filler-containing film is an anisotropic conductive film, it is preferable from the viewpoint of capture stability in terminals of electronic components. Here, the alignment of the fillers 1 in the thickness direction of the film is not limited to alignment at a single depth in the thickness direction of the film. Including embodiments in which conductive particles are present.

In order to make the optical, mechanical or electrical properties of the filler-containing film uniform, especially when the filler is used as conductive particles and the filler-containing film is configured as an anisotropic conductive film, the conductive particles are captured and short-circuited. It is preferable that the fillers 1 are arranged regularly when viewed from the top of the film. The mode of arrangement is not particularly limited, and for example, it may be a square lattice arrangement as shown in FIG. 1A in plan view of the film. In addition, examples of regular arrangement of fillers include lattice arrangements such as rectangular lattices, orthorhombic lattices, hexagonal lattices, and triangular lattices. A plurality of grids with different shapes may be combined.
As a mode of arrangement of the filler, particle rows in which the filler is linearly arranged at a predetermined interval may be arranged side by side at a predetermined interval. In addition, it may be a mode in which the filler is regularly removed in a predetermined direction of the film.

By making the fillers 1 non-contact with each other and arranging them in a regular grid pattern or the like, pressure can be applied evenly to each filler 1 when the filler-containing film is pressure-bonded to the article, and variations in the connection state can be reduced. can. In addition, by making the missing filler repeatedly exist in the longitudinal direction of the film, or by gradually increasing or decreasing the locations where the filler is missing in the longitudinal direction of the film, lot management becomes possible. It is also possible to give traceability (property that enables tracing) to the connected structure. This is also effective for prevention of counterfeiting of filler-containing films and connection structures using such films, determination of authenticity, prevention of unauthorized use, and the like.

Therefore, when the filler-containing film is configured as an anisotropic conductive film, the anisotropic conductive film is used to form the first electronic component and the second electronic component by arranging the conductive particles in a regular non-contact manner. It is possible to reduce variations in conduction resistance when components are anisotropically conductively connected. Whether or not the fillers are regularly arranged can be determined, for example, by observing whether or not the fillers are repeatedly arranged in a predetermined manner in the longitudinal direction of the film. Further, when the filler-containing film is configured as an anisotropic conductive film, the conductive particles are arranged regularly in a plan view of the film, and the positions in the film thickness direction are aligned. It is more preferable for achieving both capture stability and short-circuit suppression at terminals 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 component to be connected is wide and short-circuiting is difficult to occur, the conductive particles are dispersed randomly to the extent that they do not hinder conduction without arranging the conductive particles regularly. may be

When the fillers are arranged regularly, the lattice axis or arrangement axis of the arrangement may be parallel to the longitudinal direction of the filler-containing film or a direction orthogonal to the longitudinal direction, or may intersect the longitudinal direction of the filler-containing film. can be determined depending on the article to which the filler-containing film is crimped. For example, when the filler-containing film is an anisotropic conductive film, the lattice axis or arrangement axis of the regularly arranged conductive particles 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, as shown in FIG. and the angle θ formed between the longitudinal direction of the terminal 20 connected by the anisotropic conductive film 10A (the lateral direction of the film) and the lattice axis A is preferably 6° to 84°, more preferably 11° to Make it 74°.

In the filler-containing film, the distance between the fillers can also be determined according to the article to be connected. It can be appropriately determined according to the size and terminal pitch of the terminals to be connected by the conductive film. For example, when the anisotropic conductive film is adapted to fine-pitch COG (Chip On Glass), the distance between the nearest fillers (that is, the distance between the nearest particles) is set to the diameter D of the conductive particles in order to prevent the occurrence of short circuits. It is preferably 0.5 times or more, more preferably 0.7 times or more. On the other hand, the upper limit of the nearest filler-to-filler distance can be determined depending on the purpose of the filler-containing film. It can be 100 times or less, more preferably 50 times or less. In addition, from the viewpoint of the ability to capture the conductive particles 1 at the terminal during anisotropic conductive connection, the distance between the nearest particles is preferably 4 times or less the conductive particle diameter D, and more preferably 3 times or less. preferable.

In addition, in the filler-containing film of the present invention, the area occupation ratio of the filler calculated by the following formula is set to 0.3% or more in order to exhibit the effect of the filler.
Area occupation ratio (%) = [Number density of fillers in plan view] x [Average area of one filler in plan view] 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. The area occupancy is preferably 35% or less, more preferably 30% or less, from the viewpoint of suppressing the thrust required for the pressing jig for pressing the filler-containing film onto the article, as described later.

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

The number density value is not particularly limited as long as the area occupancy is within the above range, but when the filler-containing film is an anisotropic conductive film, the number density is practically 30 pieces/mm ^{2 .} 150 to 70,000/mm ² is preferable, and in the case of fine pitch applications, preferably 6,000 to 42,000/mm ² , more preferably 10,000 to 40,000/mm ² , and still more preferably 15,000. ˜35000/mm ² .

The number density of the filler may be obtained by observing with a metallurgical microscope as described above, or may be obtained by measuring an observed image with image analysis software (for example, WinROOF, Mitani Shoji Co., Ltd., etc.). Observation methods and measurement methods are not limited to those described above.

Further, the average planar view area of one filler can be obtained by measuring an observation image of the film surface with an electron microscope such as a metallurgical microscope or an SEM. Image analysis software may be used. Observation methods and measurement methods are not limited to those described above.

As described above, the area occupation ratio is preferably 35% or less, more preferably 30% or less, for the following reasons. That is, conventionally, in an anisotropic conductive film, the number density has been increased by narrowing the inter-particle distance of the conductive particles as long as the short circuit is not caused in order to cope with the fine pitch. However, as the number of terminals of an electronic component increases and the total connection area per electronic component increases, increasing the number density of the conductive particles will increase the pressure required for thermocompression bonding the anisotropic conductive film to the electronic component. There is a concern that the thrust force required for the jig will increase, and the conventional pressing jig will not be able to press sufficiently. The thrust force required for such a pressing jig is not limited to anisotropic conductive films, but is common to filler-containing films in general. In contrast, in the present invention, the area occupancy is preferably 35% or less, more preferably 30% or less, as described above, and the thrust force required for the pressing jig for thermocompression bonding the filler-containing film to the article is reduced to suppress.

<Filler>
In the present invention, the filler 1 may be known inorganic fillers (metals, metal oxides, metal nitrides, etc.), organic fillers (resin particles, rubber particles, etc.), organic materials, etc., depending on the application of the filler-containing film. Fillers mixed with inorganic materials (for example, particles whose core is made of a resin material and whose surface is metal-plated (metal-coated resin particles), conductive particles with insulating fine particles attached to the surface, conductive particles The surface is insulated, etc.), depending on the performance required for the application, such as hardness and optical performance. For example, in optical films and matte films, silica fillers, titanium oxide fillers, styrene fillers, acrylic fillers, melamine fillers and various titanates can be used. Titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, calcium titanate, strontium titanate, barium titanate, barium zirconate titanate, lead zirconate titanate and mixtures thereof in capacitor films etc. can be used. The adhesive film may contain polymer rubber particles, silicone rubber particles, and the like. The anisotropic conductive film contains conductive particles. Examples of conductive particles include metal particles such as nickel, cobalt, silver, copper, gold, and palladium, alloy particles such as solder, metal-coated resin particles, and metal-coated resin particles having insulating fine particles attached to their surfaces. . Two or more types can also be used together. Among them, the metal-coated resin particles are preferable because the resin particles repel each other after being connected, thereby making it easy to maintain contact with the terminal and stabilizing the conduction performance. Moreover, the surface of the conductive particles may be subjected to an insulating treatment by a known technique so as not to interfere with the conductive properties. The fillers listed above for each use are not limited to the use concerned, and may be contained in filler-containing films for other uses as necessary. Moreover, in the filler-containing film for each application, two or more fillers can be used in combination, if necessary.

The shape of the filler is appropriately selected from spherical, ellipsoidal, columnar, acicular, combinations thereof, and the like depending on the use of the filler-containing film. A spherical shape is preferable because it facilitates confirmation of the filler arrangement and facilitates maintenance of a uniform shape. In particular, in the anisotropic conductive film, the conductive particles are preferably substantially spherical. By using substantially spherical conductive particles, for example, in producing an anisotropic conductive film in which conductive particles are arranged using a transfer mold as described in Japanese Patent Application Laid-Open No. 2014-60150, transfer Since the conductive particles roll smoothly on the mold, the conductive particles can be filled at a predetermined position on the transfer mold with high precision. Therefore, the conductive particles can be precisely arranged.

Here, the substantially spherical means that the degree of sphericity calculated by the following formula 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 the cross section of the filler-containing film, and in each planar image, the area of the circumscribed circle and the area of the inscribed circle of arbitrary 100 or more (preferably 200 or more) fillers is measured, and the average value of the area of the circumscribed circle and the average value of the area of the inscribed circle are obtained to obtain the above-mentioned So and Si. Moreover, it is preferable that the sphericity is within the above range both in the surface field of view and in the cross section. The difference in surface field of view and cross-sectional sphericity is preferably within 20, more preferably within 10. The inspection of the filler-containing film during production is mainly performed by a plane view, and the detailed quality judgment after thermocompression bonding to an article is performed by both a plane view and a cross section. The sphericity can also be determined using a wet flow type particle size/shape analyzer FPIA-3000 (Malvern) if the filler is used alone.

The particle diameter 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 1 μm or more and 30 μm or less, more preferably, in order to cope with variations in wiring height, suppress an increase in conduction resistance, and suppress the occurrence of a short circuit. It is 2.5 μm or more and 9 μm or less. Depending on the object to be connected, a thickness larger than 9 μm may be suitable.

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

In the present invention, the variation in the particle diameter 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 easily pressed evenly when the filler-containing film is pressure-bonded to the article, and particularly when the fillers are arranged, the pressing force is locally concentrated. can be prevented, contributing to the stability of the connection. In addition, it is possible to accurately evaluate the connection state by means of indentation after connection. Specifically, when the filler-containing film is configured as an anisotropic conductive film, in the inspection after the anisotropic conductive connection between the anisotropic conductive film and the electronic component, even if the terminal size is large (such as FOG), Even a small one (COG, etc.) can accurately confirm the connection state by indentation. Therefore, inspection after anisotropic bonding is facilitated, and it can be expected to improve the productivity of the bonding process.

Here, the variation in particle size can be calculated using an image-type particle size analyzer or the like. The particle size of the filler, which is not contained in the filler-containing film and is used as raw material particles for the filler-containing film, can also be determined using the wet flow particle size/shape analyzer FPIA-3000 (Malvern). In this case, if the number of fillers is measured at 1000 or more, preferably 3000 or more, more preferably 5000 or more, the dispersion of individual fillers can be accurately grasped. When the filler is arranged in the filler-containing film, the sphericity can be obtained from a planar image or a cross-sectional image, as in the case of the above 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 according to the use of the filler-containing film, the production method of the filler-containing film, and the like. For example, as long as the slope 2b or undulation 2c described above can be formed, it can be about 1000 Pa·s depending on the method of manufacturing the filler-containing film. On the other hand, when a filler is held in a predetermined arrangement on the surface of a resin layer and the filler is pushed into the resin layer as a method for producing a filler-containing film, the resin layer has a minimum content of resin from the viewpoint that the film can be formed. It is preferable to set the melt viscosity to 1100 Pa·s or more.

Further, as will be described later in the manufacturing method of a filler-containing film, an inclination 2b is formed around the exposed portion of the filler 1 pressed into the resin layer 2 as shown in FIG. The minimum melt viscosity is preferably 1,500 Pa·s or more, more preferably 2,000 Pa·s or more, and still more preferably 3,000 to 15,000 Pa from the point of forming undulations 2 c directly above the filler 1 pushed into the resin layer 2 as shown. ·s, especially 3000 to 10000 Pa·s. This minimum melt viscosity can be obtained by using a rotary rheometer (manufactured by TA Instruments) as an example, holding a measuring pressure of 5 g constant, and using a measuring plate with a diameter of 8 mm. More specifically, the temperature range At 30 to 200° C., it can be obtained by setting the temperature increase rate to 10° C./min, the measurement frequency to 10 Hz, and the load variation to the measurement plate to 5 g.

By setting the minimum melt viscosity of the resin layer 2 to a high viscosity of 1500 Pa s or more, unnecessary movement of the filler can be suppressed when the filler-containing film is thermocompression bonded to the article, and in particular, the filler-containing film is an anisotropic conductive film. In this case, it is possible to prevent the conductive particles 1 to be sandwiched between terminals from flowing due to resin flow during anisotropic conductive connection.

In the case of forming the filler-dispersed layer 3 of the filler-containing film 10A by pressing the filler 1 into the resin layer 2, the resin layer 2 when the filler 1 is pressed is placed so that the filler 1 is exposed from the resin layer 2. 1 is pushed into the resin layer 2, the resin layer 2 is plastically deformed to form a slope 2b (FIG. 1B) in the resin layer 2 around the filler 1; When the filler 1 is pushed in so that the filler 1 is embedded 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 a high viscosity such as 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, and still more preferably 4500 Pa·s or more, and the upper limit is preferably 20000 Pa·s or less. It is preferably 15000 Pa·s or less, more preferably 10000 Pa·s or less. This measurement is performed in the same manner as for the minimum melt viscosity, and can be obtained by extracting the value at a temperature of 60°C.

The specific viscosity of the resin layer 2 when the filler 1 is pushed into the resin layer 2 depends on the shape and depth of the slopes 2b and 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, and still more preferably 10000 Pa·s or less. Also, such a viscosity is preferably obtained at 40-80°C, more preferably 50-60°C.

As described above, since the slope 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 pressed against the article The resistance received from the resin layer 2 is reduced as compared with the case without the slope 2b. Therefore, when the anisotropic conductive film is used as the filler-containing film, the conductive particles are easily sandwiched between the terminals during anisotropic conductive connection, thereby improving the conduction performance and the capture property.

The slope 2b preferably follows the outline of the exposed portion of the filler. This is because not only is the effect of the inclination in connection more likely to be exhibited, but also the filler can be easily recognized, thereby facilitating product inspection and the like in the production of the filler-containing film.

In addition, undulations 2c (FIGS. 4 and 6) are formed on the surface of the resin layer 2 directly above the filler 1 that is buried without being exposed from the resin layer 2, so that the article can be Pressing force from the article is more likely to be applied to the filler at the time of crimping. 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. good connection. 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 during the anisotropic conductive connection. improves.

The slope 2b and the undulations 2c may partially disappear when the resin layer is heat-pressed, but this is included in the present invention. In addition, the filler may be exposed at one point on the surface of the resin layer, and there may be inclinations or undulations around the point, but this is also encompassed by the present invention. These aspects are appropriately selected according to 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 undulations or partially eliminating the inclinations or undulations, if necessary.

(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 0.6-10. Here, the particle diameter D of the filler means its average particle diameter. If the layer thickness La of the resin layer 2 is too large, the filler tends to be misaligned when the filler-containing film is pressure-bonded to an article. Therefore, when the filler-containing film is used as an optical film, variations in optical properties occur. Moreover, when the filler-containing film is an anisotropic conductive film, the ability to capture conductive particles at the terminal anisotropically conductively connected to the electronic component is reduced. 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 other hand, if the layer thickness La of the resin layer 2 is too small and La/D is less than 0.6, it becomes difficult to maintain the filler 1 in a predetermined particle dispersion state or a predetermined arrangement by the resin layer 2 . In particular, when the filler-containing film is an anisotropic conductive film and the terminal to be connected is high-density COG, the ratio (La/D) between the layer thickness La of the insulating resin layer 2 and the conductive particle diameter D is preferably 0.6-3, more preferably 0.8-2. On the other hand, when the filler-containing film is an anisotropic conductive film, when the risk of short-circuiting 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, or a curable resin composition. The resin composition forming the resin layer 2 is appropriately selected according to the use of the filler-containing film, and whether or not the resin layer 2 should be insulating is also determined according to the use of the filler-containing film.

Here, the curable resin composition can be formed from, for example, a thermally polymerizable composition containing a thermally polymerizable compound and a thermal polymerization initiator. The thermally polymerizable composition may contain a photopolymerization initiator, if necessary.

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

A plurality of photopolymerization initiators that react to light with different wavelengths may be contained. As a result, different wavelengths can be used for the photocuring of the resin for forming the resin layer into a film during the production of the filler-containing film and the photocuring of the resin when the filler-containing film is pressure-bonded to the article.

When photocuring is performed during production of the filler-containing film, all or part of the photopolymerizable compound contained in the resin layer can be photocured. Due to this photocuring, the arrangement of the filler 1 in the resin layer 2 is maintained or fixed. Therefore, when the filler-containing film is used as an anisotropic conductive film, suppression of short circuits and improvement of trapping properties are expected. Moreover, the viscosity of the resin layer in the manufacturing process of the filler-containing film may be appropriately adjusted by this photocuring.

The 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 when the filler-containing film is pressure-bonded to the article increases.

Examples of the thermally polymerizable composition include a thermally radically polymerizable acrylate composition containing a (meth)acrylate compound and a thermally radical polymerization initiator, and a thermally cationic polymerizable epoxy system containing an epoxy compound and a thermally cationic polymerization initiator. composition and the like. A thermal anionically polymerizable epoxy composition containing a thermal anionic polymerization initiator may be used instead of the thermally cationic polymerizable epoxy composition containing a thermal cationic polymerization initiator. In addition, a plurality of types of polymerizable compositions may be used together as long as there is no particular problem. Examples of combined use include combined use of a thermally cationic polymerizable compound and a thermally radically polymerizable compound.

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

Examples of thermal radical polymerization initiators include organic peroxides and azo compounds. In particular, organic peroxides that do not generate nitrogen that causes air 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. 5 to 40 parts by mass.

Examples of epoxy compounds include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, novolac-type epoxy resins, modified epoxy resins thereof, and alicyclic epoxy resins, and two or more of these can be used in combination. can. Moreover, in addition to the epoxy compound, an oxetane compound may be used in combination.

As the thermal cationic polymerization initiator, those known as thermal cationic polymerization initiators for epoxy compounds can be employed. For example, iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, etc. that generate acid by heat can be used. and in particular aromatic sulfonium salts, which exhibit good latency with respect to temperature, can be preferably used.

If the amount of the thermal cationic polymerization initiator used is too small, it tends to cause poor curing, and if it is too large, the product life tends to be shortened. parts, more preferably 5 to 40 parts by mass.

As the thermal anionic polymerization initiator, commonly used known curing agents can be used. For example, organic acid dihydrazide, dicyandiamide, amine compound, polyamidoamine compound, cyanate ester compound, phenolic resin, acid anhydride, carboxylic acid, tertiary amine compound, imidazole, Lewis acid, Bronsted acid salt, polymercaptan curing agent , urea resins, melamine resins, isocyanate compounds, blocked isocyanate compounds, etc., and among these, one of them can be used alone, or two or more of them can be used in combination. Among these, it is preferable to use a microcapsule-type latent curing agent obtained by coating the surface of an imidazole-modified core with polyurethane.

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

In order to adjust the melt viscosity, the thermally polymerizable composition may contain an insulating filler in addition to the filler 1 described above. Examples include silica powder and alumina powder. The insulating filler is preferably a fine filler with a particle size 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 thermally polymerizable compound (photopolymerizable composition) such as an epoxy compound. is preferred. The insulating filler to be contained separately from the filler 1 is preferably used when the application of the filler-containing film is an anisotropic conductive film. may be included. When the filler-containing film is an anisotropic conductive film, the resin layer forming the filler-dispersed layer may optionally contain finer insulating fillers (so-called nano-fillers) different from the filler 1. can be done.

The filler-containing film of the present invention contains fillers, softeners, accelerators, antioxidants, colorants (pigments, dyes), organic solvents, ion catchers, etc., in addition to the insulating or conductive fillers described above. may be included.

(Position of filler in thickness direction of 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. Although it may be embedded, the distance of the deepest part of the filler from the tangential plane 2p in the central part between adjacent fillers (hereinafter referred to as the embedding amount) Lb and the ratio of the particle diameter D of the filler (Lb / D ) (hereinafter referred to as embedding rate) is preferably 60% or more and 105% or less.

By setting the embedding ratio (Lb/D) to 60% or more, the filler 1 is maintained in a predetermined particle dispersed state or in a predetermined arrangement by the resin layer 2, and by setting it to 105% or less, a filler-containing film is obtained. It is possible to reduce the amount of resin in the resin layer that causes the filler to flow unnecessarily when it is pressed against 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 the numerical value is (Lb/D). Therefore, the embedding rate of 60% or more and 105% or less means that 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. % or less.

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

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

Also, the embedding rate (Lb/D) can be obtained collectively for a certain number of objects by adjusting the focus in the plane view image. Alternatively, a laser discriminative displacement sensor (manufactured by Keyence, etc.) may be used to measure the embedding rate (Lb/D).

(Embedded rate of 60% or more and less than 100%)
As a more specific embedding mode of the filler 1 with an embedding ratio (Lb/D) of 60% or more and 105% or less, first, the filler 1 is removed from the resin layer 2 as in the filler-containing film 10A shown in FIG. 1B. A mode in which it is buried at a filling rate of 60% or more and less than 100% so as to be exposed can be mentioned. In this filler-containing film 10A, the portion of the surface of the resin layer 2 that is in contact with the filler 1 exposed from the resin layer 2 and the vicinity thereof are in contact with the surface 2a of the resin layer in the central portion between the adjacent fillers. It has a slope 2b that is recessed with respect to the plane 2p, and this recess forms a ridge line that roughly follows the contour of the filler.

Such a slope 2b or undulation 2c (FIGS. 4 and 6) is such that when a filler-containing film is produced by pressing the filler 1 into the resin layer 2, the viscosity of the resin layer 2 when the filler 1 is pressed is reduced to The lower limit 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, more preferably 15000 Pa·s or less, and still more preferably 10000 Pa·s. s or less. Also, such a viscosity is preferably obtained at 40-80°C, more preferably 50-60°C.

(Aspect with 100% embedding rate)
Next, among the filler-containing films of the present invention, as an embodiment with an embedding rate (Lb/D) of 100%, the filler shown in FIG. Similar to the containing film 10A, it has an inclination 2b that forms a ridgeline that roughly follows 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 Like the filler-containing film 10C shown in FIG. As in the filler-containing film 10D shown, there are shallow undulations 2c on the surface of the resin layer 2, and the filler 1 is exposed from the resin layer 2 at one point on the top 1a.

A small protruding portion 2q may be formed adjacent to the slope 2b of the resin layer 2 around the exposed portion of the filler or the undulation 2c of the resin layer 2 directly above the filler. An example of this is shown in filler-containing film 10C' in Figure 3B.

Since these filler-containing films 10B, 10C, 10C', and 10D have a filling 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 formed as compared with the case where the filler 1 protrudes from the resin layer 2 as shown in FIG. 1B. It is difficult for the amount of resin in the film thickness direction to become non-uniform around individual fillers during thermocompression bonding, and there is an effect that the movement of fillers due to resin flow can be reduced. Even if the embedding rate is not exactly 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 portion of the filler 1 embedded in the resin layer 2 and the surface of the resin layer 2 are flush with each other. However, movement of the filler due to resin flow can be reduced.

Among these filler-containing films 10B, 10C, 10C′, and 10D, the amount of resin around the filler 1 is less likely to be non-uniform in 10D, so movement of the filler due to resin flow can be eliminated. Since the filler 1 is exposed from the resin layer 2, the filler and the article are easily bonded, and when the filler-containing film is an anisotropic conductive film, the conductive particles 1 can be captured well at the terminal, and the conductive particles It is possible to expect the effect that even a slight movement of the Therefore, this aspect is particularly effective when the pitch is fine or the space between bumps is narrow.

Note that the filler-containing films 10B (FIG. 2), 10C (FIG. 3A), and 10D (FIG. 4) having different shapes and depths of the slopes 2b and the undulations 2c are different from each other in the resin layer 2 when the filler 1 is pushed in, as described later. can be produced by changing the viscosity of

(Embedded rate over 100% mode)
Among the filler-containing films of the present invention, when the embedding rate exceeds 100%, the filler 1 is exposed like the filler-containing film 10E shown in FIG. 2b, or, like a filler-containing film 10F shown in FIG.

The filler-containing film 10E (FIG. 5) having the slope 2b in the resin layer 2 around the exposed portion of the filler 1 and the filler-containing film 10F (FIG. 6) having the undulations 2c in the resin layer 2 directly above the filler 1 are They can be manufactured by changing the viscosity of the resin layer 2 when the filler 1 is pushed in during manufacture.

When the filler-containing film 10E shown in FIG. 5 is pressure-bonded to the article, the filler 1 is directly pressed from the article, so that the article and the filler are easily joined, and when the filler-containing film is an anisotropic conductive film, Capability of the conductive particles at the terminal is improved. Also, when the filler-containing film 10F shown in FIG. 6 is press-bonded to the article, the filler 1 does not press the article directly, but presses it through the resin layer 2. 8 (that is, a state in which the filler 1 is embedded with an embedding rate exceeding 100%, the filler 1 is not exposed from the resin layer 2, and the surface of the resin layer 2 is flat). , a pressing force is easily applied to the filler. Therefore, when the filler-containing film is an anisotropic conductive film, unwanted movement of the conductive particles 1 between terminals due to resin flow is prevented during anisotropic conductive connection.

The inclination 2b of the resin layer 2 around the exposed portion of the filler (FIGS. 1B, 2, 3A, 3B, and 5) and the undulations 2c of the resin layer directly above the filler (FIGS. 4 and 6) From the point of easily obtaining the effect, the ratio (Le/D) of the maximum depth Le of the slope 2b around the exposed portion of the filler 1 and the particle diameter D of the filler 1 is preferably less than 50%, more preferably 30%. less, more preferably 20 to 25%, and the ratio of the maximum diameter Ld of the slope 2b around the exposed portion of the filler 1 to the particle diameter D of the filler 1 (Ld/D) is preferably 100% or more, and more It is preferably 100 to 150%, and the ratio (Lf/D) of the maximum depth Lf of the undulations 2c in the resin immediately above the filler 1 to the particle diameter D of the filler 1 is greater 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 made 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. As shown in FIG. 4, the filler 1 may be exposed at one point on the top, 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 portion 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 recess due to the inclination 2b or the undulation 2c (from the tangential plane at the central portion between adjacent fillers) The distance of the deepest part of the dent) is 10% or more of the particle diameter (hereinafter simply referred to as "filler that is flush with the resin layer and has a dent depth of 10% or more"). Even if there is no problem with the performance and quality of the filler-containing film, the appearance may be impaired. In addition, when the filler-containing film and the article are laminated with the inclination 2b or undulation 2c of such a region facing the article, the inclination 2b or 2c may cause lifting after lamination. For example, when the filler-containing film is an anisotropic conductive film, if conductive particles that are flush with the insulating resin layer 2 and have a depression depth of 10% or more due to inclination or undulation are concentrated on one bump, the bump After the connection, float may occur and decrease in conductivity may occur. Therefore, in a region within 200 times the particle diameter of the filler from any filler that is flush with the resin layer 2 and has a recess depth of 10% or more, the total number of fillers is flush with the resin layer and the recess depth is 10%. % or more is preferably within 50%, more preferably within 40%, and even more preferably within 30%. On the other hand, in regions where this ratio exceeds 50%, it is preferable to shallow the dents due to the slopes 2b or the undulations 2c by, for example, 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 dents in the resin layer 2 can be confirmed after spraying. is desirable. By shallowing the dents caused by the slopes 2b or the undulations 2c in this way, the problems of appearance and floating described above 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. 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 /D) is preferably 60% or more.

In addition, in the embodiment where the embedding ratio (Lb/D) exceeds 100%, when the surface of the resin layer 2 is flat like the filler-containing film 10X of the comparative example shown in FIG. At the time of thermocompression bonding, the amount of resin interposed between the filler 1 and the terminal becomes excessively large, and the filler 1 presses the article through the resin layer instead of directly pressing the article. The filler is easily washed away by the resin flow.

In the present invention, the presence of the slopes 2b and undulations 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 in-plane observation. Observation of the slope 2b and the undulation 2c is also possible with an optical microscope and a metallurgical microscope. Also, the magnitude of the slope 2b and the undulation 2c can be confirmed by adjusting the focus during image observation. Even after the slope or undulation is reduced by heat pressing as described above, any remaining slope or undulation can be checked in a manner similar to that described above.

<Deformation mode of filler-containing film>
(Second resin layer)
In the filler-containing film of the present invention, like the filler-containing film 10H shown in FIG. You may laminate|stack the 2nd resin layer 4 with low . The second resin layer and the later-described third resin layer are layers that do not contain the filler 1 dispersed in the filler-dispersed layer. Further, like the filler-containing film 10I shown in FIG. May be laminated. The same applies when undulations 2c are formed instead of the slopes 2b.

The second resin layer 4 can also be insulating or conductive depending on the application of the filler-containing film. When the second resin layer 4 is laminated, when two articles facing each other through the filler-containing film are thermocompression-bonded, the adhesion between them can be improved. An anisotropic conductive film having an insulating resin layer as a layer is used, and when electronic components are anisotropically conductively connected, the space formed by the electrodes and bumps of the electronic components is filled with the second resin layer to connect the electronic components together. can improve the adhesion of

When connecting opposing articles using a filler-containing film having the second resin layer 4, the second resin layer 4 is formed regardless of whether the second resin layer 4 is on the surface on which the slope 2b is formed. is on the side of the article to be pressed by the thermocompression 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 tool (in other words , the resin layer 2 is on the side of the second electronic component such as a substrate placed on the stage). 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 trapping property of the conductive particles during anisotropic conductive connection. The same is true even if the slope 2b is the undulation 2c. When the first electronic component and the second electronic component are connected using an anisotropic conductive film, the first electronic component such as an IC chip is usually placed on the side of the pressing jig, and the second electronic component such as a substrate is placed on the stage. After the anisotropic conductive film is temporarily pressure-bonded to the second electronic component, the first electronic component and the second electronic component are permanently pressure-bonded. After the conductive film is temporarily attached to the first electronic component, the first electronic component and the second electronic component are permanently pressure-bonded.

The difference between the minimum melt viscosities of the resin layer 2 and the second resin layer 4 makes it easier 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 to be anisotropically conductively connected, the spaces formed by the electrodes and bumps of the electronic component are easily filled with the second insulating resin layer 4. The effect of improving the adhesiveness between them can be expected. In addition, the larger the difference, the smaller the amount of movement of the insulating resin layer 2 holding the conductive particles in the conductive particle dispersion layer relative to the second resin layer 4, so that the conductive particles can be captured at the terminal. easier to improve.

Practically, the minimum melt viscosity ratio between the resin layer 2 and the second resin layer 4 is preferably 2 or more, more preferably 5 or more, more preferably 8 or more. On the other hand, if this ratio is too large, when a long filler-containing film is wound, there is a risk that the resin will protrude or block. More specifically, the preferred 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 of the resin composition similar to that of 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 point of view of not excessively increasing the difficulty of the lamination step of the second resin layer 4, it is generally preferable to make the particle diameter 0.2 to 50 times the particle diameter of the filler. When the anisotropic conductive films 10H and 10I are used as filler-containing films, 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 μm. Double.

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

In addition, the minimum melt viscosity of the entire filler-containing films 10H and 10I, which are a combination of the resin layer 2 and the second resin layer 4, depends on the application of the filler-containing film, the thickness ratio 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 is practically 8000 Pa s or less, and in order to facilitate filling between bumps, it may be 200 to 7000 Pa s, preferably , 200 to 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 with the second resin layer 4 and the resin layer 2 interposed therebetween. The third resin layer can also be insulating or conductive depending on the application 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 spaces 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 it may be 8000 Pa s or less, or even 200 to 7000 Pa s. Well, it can also be 200 to 4000 Pa·s.

(Other lamination modes)
Depending on the application of the filler-containing film, a filler-dispersed layer may be laminated, and a layer containing no filler such as a second resin layer may be interposed between the laminated filler-dispersed layers, and furthermore, the outermost layer. may be provided with a second resin layer or a third resin layer.

<Method for producing filler-containing film>
The method for producing a filler-containing film of the present invention has a step of forming a filler-dispersed layer in which a filler is dispersed in a resin layer. The step of forming the filler-dispersed layer includes a step of holding the filler on the surface of the resin layer at a specific area occupation ratio, and a step of pushing the filler held in the resin layer into the resin layer.

Among these steps, in the step of holding the filler on the surface of the resin layer, the CV value of the particle diameter 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 occupation ratio of the filler calculated by the following formula is 0.3% or more.

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

On the other hand, in the step of pushing the filler held by the resin layer into the resin layer, the surface of the resin layer in the vicinity of the filler is inclined or undulated with respect to the tangential 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 slopes 2c described above. Among them, 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, particularly preferably 3000 to 10000 Pa s. It 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, more preferably 15000 Pa·s or less, and still more preferably 10000 Pa·s or less. is.

When the filler-containing film is formed of a single layer of the filler-dispersed layer 3, the filler-containing film of the present invention is formed by, for example, holding the fillers 1 on the surface of the resin layer 2 in a predetermined arrangement, and by forming the fillers 1 into a flat plate or It is manufactured by pressing it into a resin layer with a roller. When manufacturing a filler-containing film with an embedding rate of more than 100%, a pressing plate having projections corresponding to the arrangement of the filler may be used for pressing.

Here, the embedding amount of the filler 1 in the resin layer 2 can be adjusted by the pressing force, temperature, etc. when the filler 1 is pressed. Further, the shape and depth of the slope 2b and the undulations 2c are adjusted by the viscosity of the insulating resin layer 2 at the time of pressing, the pressing speed, the temperature, and the like.

As a method for holding the filler 1 in the resin layer 2, a known method can be used. For example, the filler 1 is directly dispersed 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 formed on the stretched film. By pressing and transferring the filler to the resin layer 2 , the filler 1 is held in the resin layer 2 . Alternatively, 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 a transfer mold is used to hold the filler 1 on the resin layer 2, the transfer mold may be, for example, inorganic materials such as silicon, various ceramics, glass, metals such as stainless steel, or organic materials such as various resins. On the other hand, it is possible to use one in which openings are formed by a known opening forming method such as a photolithographic method, or one to which a printing method is applied. Further, the transfer mold can have a shape such as a plate shape or a roll shape. In addition, the present invention is not limited to the above method.

Moreover, a second resin layer having a viscosity lower than that of the resin layer can be laminated on the surface of the resin layer into which the filler is pushed in, or on the opposite side thereof.

In order to economically press-bond the filler-containing film and the article on an industrial production line, it is preferable to manufacture the filler-containing film in a certain length. Therefore, the filler-containing film is preferably manufactured to have a length of 5 m or longer, more preferably 10 m or longer, and even more preferably 25 m or longer. On the other hand, if the filler-containing film is excessively long, it becomes difficult to use existing crimping equipment, and handling is also poor. Therefore, the filler-containing film is preferably manufactured to have a length of 5000 m or less, more preferably 1000 m or less, and even more preferably 500 m or less. In addition, such a long filler-containing film is preferably wound around a winding core to form a wound body 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 attached to an article in the same manner as conventional filler-containing films, and the article is not particularly limited as long as the filler-containing film can be attached. The filler-containing film can be attached to various articles by pressure bonding, preferably by thermocompression bonding, depending on the application. At the time of 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 is formed into one article by lightly pressing the resin layer of the filler-containing film against the article. A film stuck body stuck on 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 curved as a whole. When the article is in the form of a film or a flat plate, a pressure roller may be used to bond the filler-containing film to the article. Thereby, the filler of the filler-containing film and the article can also be directly bonded.

Alternatively, a filler-containing film may be interposed between the opposing first and second articles, and the two opposing articles may be joined with a thermocompression roller or a compression tool so that the filler is sandwiched between the articles. good. Alternatively, the filler-containing film may be sandwiched between the articles so that the filler and the articles do not come into direct contact with each other.

When the filler-containing film is an anisotropic conductive film, a thermocompression tool is used to bond the anisotropic conductive film to the first electronic component such as an IC chip, an IC module, or an FPC, the FPC, a glass substrate, or a plastic substrate. , rigid substrates, ceramic substrates, etc., for anisotropic conductive connections. The anisotropic conductive film of the present invention may be used to stack IC chips or wafers to form multiple layers. In addition, the electronic components to be connected by the anisotropic conductive film of the present invention are not limited to the electronic components described above. It can be used for various electronic parts that have been diversifying in recent years.

Therefore, the present invention includes a laminated body in which the filler-containing film of the present invention is attached to various articles by thermocompression, and a method for producing the laminated body. In particular, when the filler-containing film is an anisotropic conductive film, a method for manufacturing a connection structure that anisotropically conductively connects the first electronic component and the second electronic component using the anisotropic conductive film, and , that is, a connected 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.

As a method for connecting electronic components using an anisotropic conductive film, when the anisotropic conductive film consists of a single layer of the conductive particle dispersed layer 3, the anisotropic conductive film is attached to the second electronic component such as various substrates. The conductive particles 1 are temporarily attached from the side where the conductive particles 1 are embedded in the surface and are temporarily pressed, and the conductive particles 1 of the temporarily pressed anisotropic conductive film are not embedded in the surface First electronic components such as IC chips can be manufactured by combining and thermocompression bonding. When the insulating resin layer of the anisotropic conductive film contains not only a thermal polymerization initiator and a thermally polymerizable compound, but also a photopolymerization initiator and a photopolymerizable compound (which may be the same as the thermally polymerizable compound), A crimping method using both light and heat may be used. In this way, unwanted movement of the conductive particles can be minimized. Alternatively, the side in which the conductive particles are not embedded may be temporarily attached to the second electronic component for use. Note that the anisotropic conductive film can be temporarily attached to the first electronic component instead of the second electronic component.

Further, when the anisotropic conductive film is formed from a laminate of the conductive particle dispersed layer 3 and the second insulating resin layer 4, the conductive particle dispersed layer 3 is temporarily attached to the second electronic component such as various substrates. Then, the first electronic component such as an IC chip is aligned and placed on the second insulating resin layer 4 side of the temporarily press-bonded anisotropic conductive film, and is thermally press-bonded. The second insulating resin layer 4 side of the anisotropic conductive film may be temporarily attached to the first electronic component. Also, the conductive particle dispersed layer 3 side can be temporarily attached to the first electronic component for use.

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

Examples 1-11, Comparative Examples 1-2
(1) Production of Anisotropic Conductive Film Resin compositions for forming an insulating resin layer and a second insulating resin layer were prepared according to the formulations shown in Table 1, respectively.

A resin composition that forms an 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 an insulating thickness shown in Table 2 is applied on the PET film. A resin layer was formed. Similarly, a second insulating resin layer having a thickness shown in Table 2 was formed on the PET film.

On the other hand, a mold is prepared so that the conductive particles 1 are arranged in a square lattice as 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 28000/mm ² . bottom. That is, the projection pattern of the mold is a square lattice arrangement, the pitch of the projections on the lattice axis is twice the average conductive particle diameter (3 μm), and the lattice axis and the lateral direction of the anisotropic conductive film (terminal direction) A mold with an angle θ of 15° with respect to the longitudinal direction) is prepared, and molten pellets of a known transparent resin are poured into the mold and cooled to solidify, resulting in the dents shown in FIG. 1A. A resin mold with an array pattern was formed.

As conductive particles, metal-coated resin particles (Sekisui Chemical Co., Ltd., AUL703, average particle size 3 μm) are prepared, the conductive particles are filled in the recesses of the resin mold, and the above-mentioned insulating resin layer is covered thereon. , 60° C. and 0.5 MPa. 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 pressing (pressing conditions: 60 to 70 ° C., 0.5 MPa), and the conductive particles are dispersed. An anisotropic conductive film consisting of a single layer was produced (Examples 6 to 11 and Comparative Example 2). The state of embedding of the conductive particles was controlled by pressing conditions. The CV value of the metal-coated resin particles used was measured using FPIA-3000 (Malvern) with 1000 or more particles, and was found to be 20% or less.

The area occupancy of the conductive particles in the anisotropic conductive film thus produced is
28000 pieces/mm ² × (1.5 × 1.5 × 3.14 × 10 ^-6 ) × 100
= 19.8%.

Further, a two-layer type anisotropic conductive film was produced by laminating a second insulating resin layer on the conductive particle dispersion layer produced in the same manner (Examples 1 to 5, 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 was observed with a metallurgical microscope. In addition, for 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 near the surface of the anisotropic conductive film, the film surface is examined with a metallurgical microscope. Observed. FIG. 11A shows a top view photograph of Example 4, and FIG. 11B shows a top view photograph of Example 8. As shown in FIG.

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, a slope 2b was observed on the surface of the insulating resin layer around the conductive particles, and the surrounding surface portion (outer portion of the dotted line in FIG. 11A) was found to be flat. observed. On the other hand, in Comparative Example 1, no tilt was observed around the conductive particles.

In Example 8, the conductive particles were completely embedded in the insulating resin layer, and the conductive particles were not exposed from the insulating resin layer, but undulations 2c were observed on the surface of the insulating resin layer immediately above the conductive particles. , and the surrounding surface portion (outer portion of dotted line in FIG. 11B) was observed to be flat. In Comparative Example 2, the embedding rate was slightly higher 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 immediately above the conductive particles. I didn't.

The anisotropic conductive film of Example 7 is an example in which the slope 2b of Example 6 and the undulations 2c of Example 8 are mixed. A slope 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 immediately above the conductive particles completely embedded in the insulating resin layer, and the surrounding surface portion was observed to be flat.

(3) Evaluation The anisotropic conductive films of Examples and Comparative Examples prepared in (1) were evaluated as follows: (a) initial conduction resistance, (b) conduction reliability, and (c) particle trapping properties. measured or evaluated. Table 2 shows the results.

(a) Initial conduction resistance The anisotropic conductive film of each example and comparative example was cut with an area sufficient for connection, sandwiched between an IC for evaluating conduction characteristics and a glass substrate, heated and pressed (180 ° C. , 60 MPa, 5 seconds) to obtain each connection for evaluation, and the conduction resistance of the obtained connection for evaluation was measured by the four-probe method. The initial conduction resistance is preferably rated B or higher for practical use, and more preferably rated A. Even if the evaluation is C, there is no practical problem if the resistance is 2Ω or less.

Here, the terminal patterns of the evaluation IC and the glass substrate correspond to each other, and the sizes are as follows. Further, when connecting the evaluation IC and the glass substrate, the longitudinal direction of the anisotropic conductive film was aligned with the lateral direction of the bumps.

IC for evaluating conduction characteristics
Outline 1.8×20.0mm
thickness 0.5mm
Bump specifications Size 30×85 μm, distance between bumps 50 μm, bump height 15 μm

Glass substrate (ITO wiring)
Glass material Corning 1737F
Outline 30×50mm
thickness 0.5mm
Electrode ITO wiring

Initial conduction resistance evaluation criteria A Less than 0.3 Ω B More than 0.3 Ω and less than 1 Ω C 1 Ω or more

(b) Conductivity Reliability The connection for evaluation prepared in (a) was placed in a constant temperature bath at a temperature of 85° C. and a humidity of 85% RH for 500 hours, and then the conduction resistance was measured in the same manner as the initial conduction resistance. The conduction reliability is preferably rated B or higher for practical use, and more preferably rated A. Even if the evaluation is C, there is no practical problem if the resistance is 6Ω or less.

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

(c) Particle capturing property An IC for evaluating particle capturing property is used, and this IC for evaluation and a glass substrate (ITO wiring) corresponding to a terminal pattern are shifted by 6 μm in alignment and heated and pressurized (180 ° C., 60 MPa , 5 seconds), the number of trapped conductive particles was measured for 100 particles in a region of 6 μm×66.6 μm where the bumps of the IC for evaluation and the terminals of the substrate overlapped, and the minimum number of trapped particles was obtained, and evaluated according to the following criteria. . Practically, it is preferable that it is B evaluation or more.

IC for particle trapping evaluation
Outline 1.6×29.8mm
thickness 0.3mm
Bump specifications Size 12×66.6 μm, bump pitch 22 μm (L/S=12 μm/10 μm), bump height 12 μm

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

From Table 2, the embedding rate of the conductive particles is between 60% and 105%, the conductive particles are exposed from the insulating resin layer, and Examples 1 to 7 and 9 having a slope of 2b, and the conductive particles are insulating In Example 8, which is completely embedded in the resin layer and has undulations 2c, both the initial conduction resistance and conduction reliability are evaluated as A, and the evaluation of particle trapping property is also good, but the embedding rate is within this range. Comparative Example 1 in which the conductive particles were exposed from the insulating resin layer but had no slope 2b, and Comparative Example 2 in which the embedding rate was approximately 100%, the conductive particles were completely embedded in the insulating resin layer, and there were no undulations 2c. The particle trapping property was evaluated as C, indicating that the conductive particles could not be held during connection and could not be applied to fine pitch connection. 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 likely to be affected by the resin flow during anisotropic conductive connection, and the conductive particles to the terminal. It can be inferred that the push-in is insufficient.

In Examples 1 to 7 and 9 described above, the insulating resin layer has a minimum melt viscosity of 2000 Pa s or more and a 60° C. melt viscosity of 3000 Pa s or more, but Comparative Examples 1 and 2 have a minimum melt viscosity of 1000 Pa. ·s, 60 ° C. Melt viscosity was 1500 Pa · s, and it can be seen that 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, even when the anisotropic conductive film is a two-layer type of the conductive particle dispersed layer and the second insulating resin layer, when it is a single layer of the conductive particle dispersed layer Also, it can be seen that the evaluation of the particle trapping property is practically good.

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

In addition, the same diluted resin composition was sprayed on the surface of the anisotropic conductive film of Examples 4 and 5 where the conductive particles were exposed, and the surface was made substantially flat, and the same evaluation was performed. , almost equivalent results were obtained.

When the number of short circuits between 100 bumps was confirmed in the same manner as the method for measuring the number of short circuits described in the examples of Japanese Patent Application Laid-Open No. 2016-085983, the evaluation products obtained by measuring the initial conduction of all the examples were: None were shorted. In addition, the anisotropic conductive films of all the examples were measured for the short-circuit rate according to the method for measuring the short-circuit rate of the examples described in JP-A-2016-085982. I confirmed that there were no problems. In the case of an anisotropic conductive film obtained by kneading conductive particles into an insulating resin and dispersing them randomly, the rate of occurrence of short circuits is higher 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.

In addition, the anisotropic conductive film of Example 7, in which the slope and the undulation are mixed, obtained the same results as those of Examples 6 and 8. From this, it can be seen that the effect is exhibited when the inclination or undulation exists in the vicinity of the conductive particles. In addition, the fact that the same effect was obtained in Examples 6 to 8 indicates that a wide margin can be obtained in the manufacturing conditions of the anisotropic conductive film. As a result, various effects such as a reduction in the manufacturing cost of the anisotropic conductive film and speeding up of design changes are expected, and there are great industrial benefits.

Experimental examples 1-4
(Preparation of anisotropic conductive film)
Regarding the anisotropic conductive film used for COG connection, in order to examine 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 film were formed according to the formulations shown in 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 conductive particles are pressed into the insulating resin layer to form an anisotropic single-layer conductive particle dispersed layer. A conductive film was prepared, and a second insulating resin layer was laminated on the side of the insulating resin layer into which the conductive particles 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 in Example 1. In addition, the conductive particles were embedded as shown in Table 4 by appropriately adjusting the conditions for pressing the conductive particles.

In the production process of 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 was maintained (film shape evaluation: OK). Therefore, the embedded state of the conductive particles was observed and measured with a metallurgical microscope for the anisotropic conductive films of the experimental examples except Experimental Example 4, and the subsequent evaluation was performed.

In addition, in each experimental example except Experimental example 4, inclination or both inclination and undulation were observed. The observed embedded state satisfied the preferred range described above.

(evaluation)
(a) Initial conduction resistance and conduction reliability In the same manner as in Example 1, the initial conduction resistance and conduction reliability were each evaluated in three stages. The evaluation criteria in this case are also the same as in the first embodiment. Table 4 shows the results.

(b) Particle trapping property Particle trapping property was evaluated in the same manner as in Example 1.
As a result, all of Experimental Examples 1 to 3 were judged as B 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 had a concentration of less than 50 ppm and no practical problem.

It can be seen from Table 4 that if the minimum melt viscosity of the insulating resin layer is 1000 Pa·s or less, it is difficult to form a film having an inclined insulating resin layer near 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 a slope on the surface of the insulating resin layer near 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
(Preparation of anisotropic conductive film)
Regarding 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 film were formed according to the formulations shown in Table 5. A resin composition for forming a resin layer was prepared. In this case, the conductive particles were arranged in a hexagonal lattice 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. Also, 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 conductive particles are pressed into the insulating resin layer to form an anisotropic single-layer conductive particle dispersed layer. A conductive film was prepared, and a second insulating resin layer was laminated on the side of the insulating resin layer into which the conductive particles were pushed to prepare an anisotropic conductive film shown in Table 6. In this case, the conductive particles were embedded as shown in Table 6 by appropriately adjusting the conditions for pressing the conductive particles.

In the production process of 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 maintained (film shape evaluation: OK). Therefore, in the anisotropic conductive films of Experimental Examples other than Experimental Example 8, the embedding state of the conductive particles was observed and measured with a metallurgical microscope, and the subsequent evaluation was performed.

In each experimental example except Experimental Example 8, inclination or both inclination and undulation were observed. Table 6 shows the measured values of the most clearly observed inclination for each experimental example. . The observed embedded state satisfied the preferred range described above.

(evaluation)
(a) Initial conduction resistance and conduction reliability (i) initial conduction resistance and (ii) conduction reliability were evaluated as follows. Table 6 shows the results.

(i) Initial conduction resistance Cut the anisotropic conductive film obtained in each experimental example into an area sufficient for connection, sandwich it between an FPC for evaluating conduction characteristics and a non-alkali glass substrate, and measure the width of the thermocompression bonding tool. It was heated and pressed at 1.5 mm (180° C., 4.5 MPa, 5 seconds) to obtain each connection for evaluation. The conduction resistance of the obtained connections for evaluation was measured by the four-probe method, and the measured values were evaluated according to the following criteria.

FPC for evaluating conduction characteristics:
Terminal pitch 20μm
Terminal width/inter-terminal space 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 2.0 Ω NG: 2.0 Ω or more

(ii) Continuity reliability The connection for evaluation prepared 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. Values were evaluated according to the following criteria.

Evaluation criteria for conduction reliability OK: less than 5.0 Ω NG: 5.0 Ω or more

(b) Particle Capability The number of trapped conductive particles was measured with respect to 100 terminals of the connection for evaluation produced in (i), and the minimum number of trapped particles was obtained. If the minimum captured number is 10 or more, there is no practical problem.
In all of Experimental Examples 5 to 7, the minimum captured number was 10 or more.

(c) Short-circuit occurrence rate The number of short-circuits of the connection for evaluation produced in (i) was measured, and the short-circuit occurrence rate was obtained from the measured number of short-circuits and the number of gaps of the connection for evaluation. In all of Experimental Examples 5 to 7, the occurrence rate of short circuits was less than 50 ppm, confirming that there is no practical problem.

It can be seen from Table 6 that it is difficult to form a film having a slope on the surface of the insulating resin layer in the vicinity of the conductive particles if the minimum melt viscosity of the insulating resin layer is 1000 Pa·s or less. 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 a slope on the surface of the insulating resin layer near 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.

REFERENCE SIGNS LIST 1 filler, conductive particles 1a top of filler 2 resin layer, insulating resin layer 2a surface of resin layer 2b inclination 2c undulation 2f flat surface portion 2p tangential plane 2q protruding portion 3 filler dispersed layer, conductive particle dispersed layer 4 second layer Resin Layer, Second Insulating Resin Layer 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I Filler-Containing Film, Anisotropic Conductive Film 20 of Example Terminal A Lattice Axis D Conductive Particle Diameter, Filler Particle diameter La Layer thickness of the resin layer Lb Embedding amount (distance of the deepest part of the conductive particles from the tangential plane in the central part between adjacent conductive particles)
Lc exposed diameter Ld maximum diameter of slope Le maximum depth of slope Lf maximum depth of undulation θ angle between longitudinal direction of terminal and lattice axis of arrangement of conductive particles

Claims (26)

A filler-containing film having a filler-dispersed 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 undulations with respect to the tangential plane of the resin layer in the central portion between adjacent fillers,
In the inclination, the surface of the resin layer around the filler is lacking with respect to the tangential plane,
In the undulations, the amount of resin in the resin layer directly above the filler is smaller than when the surface of the resin layer directly above the filler is on the tangential plane ,
Filler Area Occupancy Area Area Occupancy (%) = [number density of filler in plan view ] x [average area of one filler in plan view] x 100
is 0.3% or more. 2. The filler-containing film according to claim 1, wherein the filler has a sphericity of 70-100. 3. The filler-containing film according to claim 1, wherein the ratio (Lb/D) of the distance Lb of the deepest part of the filler from the tangential plane to the particle diameter D of the filler is 60% or more and 105% or less. 4. The filler-containing film according to any one of claims 1 to 3, wherein the filler is exposed from the resin layer. 4. The filler-containing film according to any one of claims 1 to 3, 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 5 , wherein the ratio (Le/D) of the depth Le from the tangential plane of the slope or undulation to the particle diameter D of the filler is less than 50%. The filler-containing film according to any one of claims 1 to 6 , wherein the ratio (Ld/D) of the maximum diameter Ld of the slope or undulation to the particle diameter D of the filler is 100% or more. The filler-containing film according to any one of claims 1 to 7 , wherein the ratio (La/D) of the layer thickness La of the resin layer to the particle diameter D of the filler is 0.6-10. The filler-containing film according to any one of claims 1 to 8 , wherein the fillers are arranged without contacting each other. 10. The filler-containing film according to any one of claims 1 to 9 , wherein the distance between the closest filler particles is 0.5 times or more the particle diameter of the filler. 11. The filler-containing film according to any one of claims 1 to 10 , wherein a second resin layer is laminated on the surface of the filler-dispersed layer opposite to the surface on which the resin layer is inclined or undulated. The filler-containing film according to any one of claims 1 to 10 , wherein a second resin layer is laminated on the sloped or undulating surface of the resin layer of the filler-dispersed layer. 3. The filler-containing film according to claim 1 , wherein the minimum melt viscosity of the second resin layer is lower than the minimum melt viscosity of the resin layer of the filler-dispersed layer. The filler-containing film according to any one of claims 1 to 13, wherein the resin layer of the filler-dispersed layer has a viscosity at 60°C of greater than 1100 Pa·s. The filler-containing film according to any one of claims 1 to 14 , wherein the filler is conductive particles, the resin layer of the filler-dispersed layer is an insulating resin layer, and is used as an anisotropic conductive film. A film-attached body in which the filler-containing film according to any one of claims 1 to 15 is attached to an article. A connected 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 15 . A connection structure in which a first electronic component and a second electronic component are anisotropically conductively connected via the filler-containing film according to claim 15 . A method for producing a connected 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 15 . The first electronic component and the second electronic component are thermocompression bonded via the filler-containing film according to claim 1 to 5 , thereby anisotropically conductively connecting the first electronic component and the second electronic component to manufacture a connected structure. A method of manufacturing a connection structure that A method for producing a filler-containing film, comprising a step of forming a filler-dispersed layer in which a filler is dispersed in a resin layer,
The step of forming the filler-dispersed layer is a step of holding the filler on the surface of the resin layer;
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 on the surface of the resin layer, the area occupation ratio of the filler calculated by the following formula Area occupation ratio (%) = [plan view Number density of fillers in] × [average planar view area of one filler] × 100
is 0.3% or more,
In the step of pressing the filler into the resin layer, the surface of the resin layer in the vicinity of the filler has an inclination or undulations with respect to the tangential plane of the resin layer in the central portion between the adjacent fillers, and the inclination is such that the resin layer around the filler The surface of is chipped with respect to the tangential plane, and in the undulations, the amount of resin in the resin layer directly above the filler is less than when the surface of the resin layer directly above the filler is on the tangential plane. A method for producing a filler-containing film by adjusting the viscosity, pushing speed or temperature of the resin layer when the filler is pushed. 22. The method for producing a filler-containing film according to claim 21, wherein the filler has a sphericity of 70-100. In the step of pressing the filler into the resin layer, the ratio (Lb/D) of the distance Lb of the deepest part of the filler from the tangential plane and the particle diameter D of the filler is 60% or more and 105% or less. 23. The method for producing a filler-containing film according to claim 21 or 22, 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, holding the filler in a predetermined arrangement on the surface of the resin layer,
24. The method for producing a filler-containing film according to any one of claims 21 to 23, wherein in the step of pressing the filler into the resin layer, the filler is pressed into the resin layer with a flat plate or a roller. 25. Any one of claims 21 to 24, wherein in the step of holding the filler on the surface of the resin layer, the filler is filled in the transfer mold and transferred to the resin layer to hold the filler in a predetermined arrangement on the surface of the resin layer. A method for producing a filler-containing film according to 1. In order to use the filler-containing film as an anisotropic conductive film, the conductive particles are used as the filler, and the insulating resin layer is used as the resin layer of the filler-dispersed layer. A method for producing a filler-containing film.

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