JP2022069457A - Anisotropic conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive film capable of corresponding to a bump of a narrow pitch and reducing number density of conductive particles more than that of a conventional anisotropic conductive film.

SOLUTION: Disclosed is an anisotropic conductive film 1A in which a conductive particle 2 is arranged in an insulating resin binder 3. A polygon repeating unit 5 formed by sequentially connect the centers of a plurality of conductive particle 2 is repeatedly arranged in vertical and horizontal directions in a plan view. A polygon side of the repeating unit 5 obliquely crosses the longitudinal direction or the transverse direction of the anisotropic conductive film.

SELECTED DRAWING: Figure 2A

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an anisotropic conductive film.

An anisotropic conductive film in which conductive particles are dispersed in an insulating resin binder is widely used when mounting electronic components such as IC chips on a wiring board or the like. In anisotropic conductive films, it is strongly required to improve the catchability of conductive particles in bumps and avoid short circuits between adjacent bumps by narrowing the pitch of bumps due to high-density mounting of electronic components. ..

In response to such a request, it has been proposed to arrange the conductive particles in the anisotropic conductive film in a grid pattern and to incline the arrangement axis with respect to the longitudinal direction of the anisotropic conductive film (patented). Document 1, Patent Document 2).

Japanese Patent No. 4887700 Japanese Unexamined Patent Publication No. 9-320345

As described in Patent Documents 1 and 2, when the conductive particles are arranged in a simple lattice pattern, the bump layout is supported by the inclination angle of the arrangement axis and the distance between the conductive particles. Therefore, when the bumps have a narrow pitch, the distance between the conductive particles has to be narrowed, the number density of the conductive particles increases, and the manufacturing cost of the anisotropic conductive film increases.

Further, in order to narrow the distance between the conductive particles and avoid a short circuit, it is necessary to prevent the conductive particles from being washed away by the resin flow of the insulating resin binder at the time of anisotropic conductive connection. There are also restrictions on the design of insulating resin binders.

Therefore, it is an object of the present invention to be able to cope with bumps having a narrow pitch and to reduce the number density of conductive particles as compared with the conventional anisotropic conductive film.

The present inventor does not arrange the conductive particles in a plan view of the anisotropic conductive film in a simple lattice pattern, but repeatedly arranges the conductive particles vertically and horizontally by repeating a polygonal unit composed of a plurality of conductive particles, and many of them. The present invention has been conceived by finding that the above-mentioned problems can be solved by diagonally intersecting the polygonal sides with respect to the longitudinal direction or the lateral direction of the anisotropic conductive film.

That is, the present invention is an anisotropic conductive film in which conductive particles are arranged on an insulating resin binder.
In a plan view, polygonal repeating units formed by sequentially connecting the centers of a plurality of conductive particles are repeatedly arranged.
Provided is an anisotropic conductive film in which the polygon of the repeating unit has an obliquely intersecting side in the longitudinal direction or the lateral direction of the anisotropic conductive film.

According to the anisotropic conductive film of the present invention, the individual conductive particles are not arranged in a simple lattice pattern, but the repeating units formed of a plurality of conductive particles are repeatedly arranged, so that the distance between the particles of the conductive particles is increased. The narrowed portion is uniformly present throughout the film. Further, since the polygon of the repeating unit has a side diagonally intersecting with the longitudinal direction or the lateral direction of the anisotropic conductive film, the catchability of the conductive particles in the bump is high. Therefore, narrow pitch bumps can be connected without causing a short circuit.

On the other hand, according to the anisotropic conductive film of the present invention, since the portion where the distance between the conductive particles is widened is uniformly present in the entire film, the number density of the conductive particles in the entire anisotropic conductive film can be increased. It can be suppressed and the increase in manufacturing cost due to the increase in the number density of conductive particles can be suppressed. Further, by suppressing the increase in the number density of the conductive particles, it is possible to suppress the increase in the thrust required for the pressing jig at the time of anisotropic conductive connection. Therefore, it is possible to reduce the pressure applied to the electronic component from the pressing jig at the time of anisotropic conductive connection and prevent the electronic component from being deformed.

FIG. 1A is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1A of the embodiment. FIG. 1B is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1A of the embodiment. FIG. 1C is a cross-sectional view of the anisotropic conductive film 1A of the embodiment. FIG. 2A is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Ba of the embodiment. FIG. 2B is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Bb of the embodiment. FIG. 3A is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Ca of the embodiment. FIG. 3B is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Cb of the embodiment. FIG. 4A is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Da of the embodiment. FIG. 4B is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Db of the embodiment. FIG. 5A is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Ea of the embodiment. FIG. 5B is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1Eb of the embodiment. FIG. 6 is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1F of the embodiment. FIG. 7 is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1G of the embodiment. FIG. 8 is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1H of the embodiment. FIG. 9 is a plan view illustrating the arrangement of the conductive particles of the anisotropic conductive film 1I of the embodiment. FIG. 10 is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1J of the embodiment. FIG. 11 is a plan view illustrating the arrangement of the conductive particles of the anisotropic conductive film 1K of the embodiment. FIG. 12 is a plan view illustrating the arrangement of conductive particles in the anisotropic conductive film 1L of the embodiment. FIG. 13 is a plan view illustrating the arrangement of the conductive particles of the anisotropic conductive film 1M of the embodiment. FIG. 14 is a cross-sectional view of the anisotropic conductive film 1a of the embodiment. FIG. 15 is a cross-sectional view of the anisotropic conductive film 1b of the embodiment. FIG. 16 is a cross-sectional view of the anisotropic conductive film 1c of the embodiment. FIG. 17 is a cross-sectional view of the anisotropic conductive film 1d of the embodiment. FIG. 18 is a cross-sectional view of the anisotropic conductive film 1e of the embodiment.

Hereinafter, the anisotropic conductive film of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals represent the same or equivalent components.

<Overall composition of anisotropic conductive film>
FIG. 1A is a plan view showing the arrangement of conductive particles of the anisotropic conductive film 1A according to the embodiment of the present invention, and FIG. 1C is a cross-sectional view thereof.
The anisotropic conductive film 1A has a structure in which the conductive particles 2 are arranged in a single layer on or near the surface of the insulating resin binder 3, and the insulating adhesive layer 4 is laminated on the surface.

The anisotropic conductive film of the present invention may be configured such that the insulating adhesive layer 4 is omitted and the conductive particles 2 are embedded in the insulating resin binder 3.

<Conductive particles>
As the conductive particles 2, those used in known anisotropic conductive films can be appropriately selected and used. For example, metal particles such as nickel, copper, silver, gold, and palladium, and metal-coated resin particles in which the surface of resin particles such as polyamide and polybenzoguanamine are coated with a metal such as nickel can be mentioned. The size of the arranged conductive particles is preferably 1 μm or more and 30 μm or less, more preferably 1 μm or more and 10 μm or less, and further preferably 2 μm or more and 6 μm or less.

The average particle size of the conductive particles 2 can be measured by an image-type or laser-type particle size distribution meter. The anisotropic conductive film may be observed in a plan view and the particle size may be measured to obtain the particle size. In that case, preferably 200 or more, more preferably 500 or more, and even more preferably 1000 or more are measured.

The surface of the conductive particles 2 is preferably coated with an insulating coat, an insulating particle treatment, or the like. It is assumed that such a coating is easily peeled off from the surface of the conductive particles 2 and does not interfere with the anisotropic conductive connection. Further, protrusions may be provided on the entire surface or a part of the surface of the conductive particles 2. The height of the protrusions is preferably within 20%, preferably within 10% of the diameter of the conductive particles.

<Arrangement of conductive particles>
In FIGS. 1A to 7 below, an example of arranging the repeating unit when the polygonal repeating unit 5 is trapezoidal will be described as an example.
In the arrangement of the conductive particles 2 in the plan view of the anisotropic conductive film 1A shown in FIG. 1A, the polygonal repeating units 5 formed by sequentially connecting the centers of the plurality of conductive particles 2a, 2b, 2c, and 2d are orthogonal to each other. It is repeated in two directions (X direction and Y direction), and is arranged on one surface (that is, as a whole) of the anisotropic conductive film 1. The anisotropic conductive film of the present invention can have a region in which conductive particles are not arranged, if necessary.

In the arrangement of the conductive particles 2, the conductive particles are arranged at a part of the vertices of the regular triangle when the regular triangles are arranged without gaps (or the vertices of the regular hexagon when the regular hexagons are arranged without gaps). It can also be seen as a thing. In other words, it can be said that the arrangement is such that the conductive particles at a predetermined lattice point are regularly removed from the arrangement in which the conductive particles are present at each lattice point of the hexagonal lattice. Therefore, the apex of the trapezoid of the repeating unit 5 composed of the conductive particles 2a, 2b, 2c, and 2d is a part of the regular hexagon obtained by combining the regular triangles, and exists at the grid points of the hexagonal lattice. When this trapezoid is inverted around one side 2a and 2b, the sides 2c and 2d overlap with the sides 2g and 2h of the adjacent trapezoidal repeating unit (that is, the repeating unit consisting of conductive particles 2e, 2f, 2g and 2h). ..

When considering the repeating unit of the conductive particles 2, as shown in FIG. 1B, the regular hexagonal repeating unit 5x composed of the conductive particles 2p, 2q, 2r, 2s, 2t, and 2u has one side in the X direction. It can be seen that the repeating unit is repeated while overlapping, and the sides and vertices are not overlapped in the Y direction. However, in the present invention, the repeating unit is a polygon composed of four or more conductive particles, and the number thereof is large. It is preferable to regard it as a polygon, which is the smallest unit that repeats vertically and horizontally in an anisotropic conductive film without overlapping the sides of the square.

Each side of the trapezoid of the repeating unit 5 (FIG. 1A) is obliquely intersected with the longitudinal direction and the lateral direction of the anisotropic conductive film 1A. As a result, the circumscribed line L1 of the conductive particles 2a in the longitudinal direction of the anisotropic conductive film penetrates the conductive particles 2b adjacent to the conductive particles 2a in the longitudinal direction of the anisotropic conductive film. Further, the circumscribed line L2 of the conductive particles 2a in the lateral direction of the anisotropic conductive film penetrates the conductive particles 2a adjacent to the conductive particles 2a in the lateral direction in the lateral direction. Generally, at the time of anisotropic conductive connection, the longitudinal direction of the anisotropic conductive film is the lateral direction of the bump, so that the polygonal side of the repeating unit 5 is the longitudinal direction or the lateral direction of the anisotropic conductive film 1A. When crossed, it is possible to prevent multiple conductive particles from lining up linearly along the edge of the bump, which causes the plurality of linearly aligned conductive particles to come together from the terminal and not contribute to conduction. Since this phenomenon can be avoided, the catchability of the conductive particles 2 can be improved.

In the present invention, the repeating unit does not necessarily have all sides obliquely intersected with the longitudinal direction or the lateral direction of the anisotropic conductive film, but the lateral direction of each bump is anisotropic conductive. In the case of the longitudinal direction of the film, it is preferable that each side of the repeating unit is obliquely intersected with the longitudinal direction or the lateral direction of the anisotropic conductive film from the viewpoint of capturing conductive particles.

On the other hand, when the arrangement pattern of the bumps is radial (so-called fan-out bumps), it is preferable that the polygon forming the repeating unit has sides in the longitudinal direction or the lateral direction of the anisotropic conductive film. That is, in order to prevent the bumps to be connected from being displaced due to thermal expansion, the bump arrangement pattern may be radial (for example, JP-A-2007-19550, JP-A-2015-232660, etc.). ), In that case, the angle formed by the longitudinal direction of each bump and the longitudinal direction and the lateral direction of the anisotropic conductive film gradually changes. Therefore, even if the polygonal side of the repeating unit 5 is not skewed in the longitudinal direction or the lateral direction of the anisotropic conductive film, the repeating unit 5 is formed with respect to the longitudinal edge of each of the radially arranged bumps. The sides of the polygon intersect diagonally. Therefore, it is possible to avoid the phenomenon that most of the conductive particles on the edge of the bump at the time of anisotropic conductive connection are not captured by the bump and the capture property of the conductive particles is lowered.

On the other hand, the radial arrangement pattern of bumps is usually formed symmetrically. Therefore, the polygonal shape forming the repeating unit 5 has sides in the longitudinal direction or the lateral direction of the anisotropic conductive film from the viewpoint of facilitating confirmation of the quality of the connection state by the indentation after the anisotropic conductive connection. In particular, the polygon forming the repeating unit 5 has a longitudinal or longitudinal side of the anisotropic conductive film, and a symmetric shape having the anisotropic conductive film in the lateral or longitudinal direction as the axis of symmetry. Therefore, it is preferable that the repeating unit 5 is repeatedly arranged in the longitudinal direction or the lateral direction of the anisotropic conductive film. For example, as in the anisotropic conductive film 1Ba shown in FIG. 2A, the trapezoidal shape of the repeating unit 5 is a trapezoidal shape having an axis of symmetry in the lateral direction of the anisotropic conductive film, and the bottom and top sides thereof are the lengths of the anisotropic conductive film. It may be parallel to the direction, or the bottom and top sides of a similar trapezoidal repeating unit as in the anisotropic conductive film 1Bb shown in FIG. 2B may be parallel to the lateral direction of the anisotropic conductive film.

In the present invention, the arrangement of the conductive particles 2 in the repeating unit 5 and the vertical and horizontal repeating pitches of the repeating unit 5 can be appropriately changed according to the shape and pitch of the terminals to be connected to the anisotropic conductive connection. Therefore, compared to the case where the conductive particles 2 are arranged in a simple lattice pattern, high catchability can be achieved with a small number of conductive particles as a whole anisotropic conductive film. For example, in order to increase the number density of the conductive particles in the longitudinal direction of the anisotropic conductive film with respect to the above-mentioned anisotropic conductive film 1Ba, a trapezoidal repeating unit 5 like the anisotropic conductive film 1Ca shown in FIG. 3A 5 Was repeated in the width direction of the anisotropic conductive film with its shape, and in the longitudinal direction of the anisotropic conductive film, the trapezoidal repeating unit 5 and the trapezoidal repeating unit were inverted along the longitudinal axis of the film. The arrangement may be such that the repeating unit 5B of the shape is alternately repeated. In this case, as in the anisotropic conductive film 1Da shown in FIG. 4A, the trapezoidal repeating unit 5 and the inverted repeating unit 5B are alternately repeated in the lateral direction of the anisotropic conductive film. May be good.

Similarly, in order to increase the number density of the conductive particles in the lateral direction of the anisotropic conductive film with respect to the above-mentioned anisotropic conductive film 1Bb, the anisotropic conductive film 1Cb shown in FIG. 3B is different from the anisotropic conductive film 1Bb. The trapezoidal repeating unit 5 is repeated in the longitudinal direction of the hydrophobic conductive film in its shape, and the repeating unit 5 and the repeating unit are repeated in the width direction of the anisotropic conductive film in the lateral direction of the anisotropic conductive film. The arrangement may be such that the repeating unit 5B having the shape inverted by the shaft is alternately repeated. Further, as in the anisotropic conductive film 1Db shown in FIG. 4B, the repeating unit 5 and the repeating unit 5B having an inverted shape thereof are alternately repeated in both the longitudinal direction and the lateral direction of the anisotropic conductive film. May be.

Further, in order to reduce the number density of the anisotropic conductive film in the lateral direction with respect to the above-mentioned anisotropic conductive film 1Ca, the repeating units 5 and 5B are different as in the anisotropic conductive film 1Ea shown in FIG. 5A. The spacing between the repeating rows of the anisotropic conductive film in the longitudinal direction may be widened, and the repeating unit 5 may be used as in the anisotropic conductive film 1Eb shown in FIG. 5B in order to reduce the number density of the anisotropic conductive film in the longitudinal direction. The spacing between the repeating rows of the anisotropic conductive film of 5B in the width direction may be widened.

Further, as in the anisotropic conductive film 1F shown in FIG. 6, the repeating pitch in the Y direction of the repeating unit 5 may be widened with respect to the arrangement of the conductive particles of the anisotropic conductive film 1A shown in FIG. 1A. In the arrangement of the conductive particles 2 shown in FIG. 1A, each conductive particle 2 overlaps with one of the vertices of the regular hexagon when the regular hexagons are arranged without gaps, but in the arrangement of the conductive particles shown in FIG. It differs from the arrangement of the conductive particles shown in FIG. 1A in that all the conductive particles do not necessarily become the vertices of the regular hexagon when the regular hexagons are arranged without gaps.

Further, as in the anisotropic conductive film 1G shown in FIG. 7, the repeating pitch in the Y direction may be further widened, and the single conductive particles 2p may be arranged between the repeating units 5 adjacent in the Y direction, and further separately. You may arrange the repeating unit of. Further, the repeating pitch in the X direction of the repeating unit 5 may be appropriately changed, or a single conductive particle or a separate repeating unit may be arranged between the repeating pitches in the X direction.

Like the anisotropic conductive film 1H shown in FIG. 8, the trapezoidal repeating unit 5 or the repeating unit 5B obtained by inverting the trapezoidal repeating unit 5 is repeated in the lateral direction or the longitudinal direction of the anisotropic conductive film, and the repeating unit 5 is repeated. A single row of conductive particles 2p may be arranged between the row in the width direction of the anisotropic conductive film and the row in the width direction of the anisotropic conductive film of the repeating unit 5B. As a result, the conductive particles 2 are arranged in the orthorhombic lattice, and the single conductive particles 2p are present in the center of the unit lattice. In order to reduce the number density of the conductive particles when the conductive particles are arranged in an orthorhombic lattice, the repeating unit 5 itself may be formed in a rhombus shape as in the anisotropic conductive film 1I shown in FIG. By arranging the conductive particles 2 in an orthorhombic lattice pattern as shown in FIGS. 8 and 9, the conductive particles 2 exist in the longitudinal direction, the lateral direction, and the direction inclined with respect to them in the longitudinal direction and the lateral direction of the anisotropic conductive film. Therefore, it becomes easy to improve the catchability of the conductive particles and suppress the short circuit at the time of anisotropic conductive connection.

Further, as in the anisotropic conductive film 1J shown in FIG. 10, a rhombic repeating unit 5 composed of four conductive particles is arranged in a rectangular lattice pattern, and the repeating unit 5 is arranged in the longitudinal direction of the anisotropic conductive film. The rectangular grid-like array of the rhombic repeating units 5B inverted in the lateral direction may be overlapped so that the grid points do not overlap. Like the anisotropic conductive film 1K shown in FIG. 11, the particle arrangement is the same as that of the anisotropic conductive film 1J of FIG. Is also good.

The repeating unit is not limited to the arrangement in which the conductive particles occupy a part of the vertices (that is, the grid points of the hexagonal lattice) of the regular hexagon when the regular triangles are arranged without gaps. Conductive particles may occupy a part of the lattice points of the square lattice. For example, the arrangement in which the trapezoidal shape similar to the arrangement of the conductive particles shown in FIG. 5A is repeated alternately in the longitudinal direction and the lateral direction of the anisotropic conductive film is shown. Like the anisotropic conductive film 1L shown in No. 12, it can be formed on the lattice points of a square lattice.

Further, the number of polygonal vertices of the repeating unit is not limited to 4, and may be 5 or more, 6 or more, or 7 or more. However, in order to make it easier to recognize the shape of the repeating unit in the design and production process of manufacturing the anisotropic conductive film, it is preferable that the number of vertices of the repeating unit is an even number.

The shape of the polygon forming the repeating unit may be a regular polygon or not a regular polygon, but a shape having an axis of symmetry is preferable from the viewpoint of making it easier to recognize the shape of the repeating unit. In this case, each conductive particle constituting the repeating unit does not have to be present at the grid points of the hexagonal grid or the square grid. For example, as in the anisotropic conductive film 1M shown in FIG. 13, the repeating unit 5 may be composed of conductive particles located at the vertices of a regular octagon. The polygonal shape of the repeating unit is the shape and pitch of the bumps or terminals that are anisotropically conductively connected, the angle of inclination of the bumps or terminals in the longitudinal direction of the anisotropic conductive film with respect to the film longitudinal direction, and the insulation of the anisotropic conductive film. It can be appropriately determined according to the resin composition of the sex resin binder and the like.

The arrangement of the conductive particles in the present invention is not limited to the arrangement of the repeating units shown in the figure, and may be, for example, an inclined arrangement of the repeating units shown in the drawing. In this case, a 90 ° tilted film, that is, an aspect in which the longitudinal direction and the lateral direction of the film are interchanged is also included. Further, the interval between the repeating units and the interval between the conductive particles in the repeating unit may be changed.

<Minimum inter-particle distance of conductive particles>
The shortest inter-particle distance of the conductive particles is preferably 0.5 times or more the average particle diameter of the conductive particles, both between adjacent conductive particles in the repeating unit and between adjacent conductive particles between the repeating units. If this distance is too short, short circuits are likely to occur due to contact between conductive particles. The upper limit of the distance between adjacent conductive particles is determined according to the bump shape and bump pitch. For example, in the case of a bump width of 200 μm and a bump-to-bump space of 200 μm, when at least one conductive particle is present in either the bump width or the bump-to-bump space, the shortest inter-particle distance of the conductive particles is less than 400 μm. From the viewpoint of ensuring the trapping property of conductive particles, it is preferably less than 200 μm.

<Number density of conductive particles>
The number density of the conductive particles is conductive from the viewpoint of suppressing the manufacturing cost of the anisotropic conductive film and preventing the thrust required for the pressing jig used for the anisotropic conductive connection from becoming excessively large. When the average particle size of the particles is less than 10 μm, 50,000 particles / mm ² or less is preferable, 35,000 particles / mm ² or less is more preferable, and 30,000 particles / mm ² or less is further preferable. On the other hand, if the number density of the conductive particles is too small, there is a concern about conduction failure due to insufficient capture of the conductive particles by the terminals, so 300 particles / mm ² or more is preferable, and 500 particles / mm ² or more is more preferable. , 800 pieces / mm ² or more is more preferable.

When the average particle diameter of the conductive particles is 10 μm or more, 15 particles / mm ² or more is preferable, 50 particles / mm ² or more is more preferable, and 160 particles / mm ² or more is further preferable. This is because the larger the diameter of the conductive particles, the higher the occupied area ratio of the conductive particles. For the same reason, 1800 pieces / mm ² or less is preferable, 1100 pieces / mm ² or less is more preferable, and 800 pieces / mm ² or less is further preferable.

The number density of the conductive particles may deviate locally (for example, 200 μm × 200 μm) from the above-mentioned number density.

<Insulating resin binder>
As the insulating resin binder 3, a heat-polymerizable composition, a photopolymerizable composition, a photothermally-combined polymerizable composition and the like used as an insulating resin binder in a known anisotropic conductive film are appropriately selected and used. can do. Among these, the heat-polymerizable composition includes a heat-radical polymerizable resin composition containing an acrylate compound and a heat-radical polymerization initiator, a heat-cationic polymerizable resin composition containing an epoxy compound and a heat-cationic polymerization initiator, and an epoxy compound. Examples thereof include a thermal anionic polymerizable resin composition containing a thermal anionic polymerization initiator and a thermal anionic polymerizable resin composition, and examples of the photopolymerizable composition include a photoradical polymerizable resin composition containing an acrylate compound and a photoradical polymerization initiator. Can be given. If no particular problem occurs, a plurality of kinds of polymerizable compositions may be used in combination. Examples of the combined use include a combination of a thermally cationically polymerizable composition and a thermally radically polymerizable composition.

Here, as the photopolymerization initiator, a plurality of types that react with light having different wavelengths may be contained. As a result, the wavelength used for photocuring the resin constituting the insulating resin layer at the time of manufacturing the anisotropic conductive film and photocuring the resin for adhering the electronic components to each other at the time of anisotropic conductive connection can be determined. It can be used properly.

When the insulating resin binder 3 is formed by using the photopolymerizable composition, all or part of the photopolymerizable compound contained in the insulating resin binder 3 is obtained by photocuring during the production of the anisotropic conductive film. Can be photocured. By this photo-curing, the arrangement of the conductive particles 2 in the insulating resin binder 3 is maintained or fixed, and it is expected that short-circuit suppression and improvement of capture are expected. Further, by adjusting the photocuring conditions, the viscosity of the insulating resin layer in the manufacturing process of the anisotropic conductive film can be adjusted.

The blending amount of the photopolymerizable compound in the insulating resin binder 3 is preferably 30% by mass or less, more preferably 10% by mass or less, still more preferably less than 2% by mass. This is because if the amount of the photopolymerizable compound is too large, the thrust applied to the push-in at the time of anisotropic conductive connection increases.

On the other hand, the thermopolymerizable composition contains a thermopolymerizable compound and a thermopolymerization initiator, and as the thermopolymerizable compound, one that also functions as a photopolymerizable compound may be used. Further, the thermopolymerizable composition may contain a photopolymerizable compound in addition to the thermopolymerizable compound, and may also contain a photopolymerizable initiator. Preferably, the photopolymerizable compound and the photopolymerization initiator are contained separately from the thermopolymerizable compound. For example, a thermal cationic polymerization initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermal polymerizable compound, a photoradical initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. The insulating binder 3 may include a cured product of these polymerizable compositions.

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

Further, the epoxy compound used as the polymerizable compound forms a three-dimensional network structure and imparts good heat resistance and adhesiveness, and it is preferable to use a solid epoxy resin and a liquid epoxy resin in combination. Here, the solid epoxy resin means an epoxy resin that is solid at room temperature. The liquid epoxy resin means an epoxy resin that is liquid at room temperature. Further, the normal temperature means a temperature range of 5 to 35 ° C. defined by JIS Z 8703. In the present invention, two or more kinds of epoxy compounds can be used in combination. Further, an oxetane compound may be used in combination with the epoxy compound.

The solid epoxy resin is not particularly limited as long as it is compatible with the liquid epoxy resin and is solid at room temperature. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyfunctional epoxy resin, dicyclopentadiene type epoxy resin, Novolak phenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin and the like can be mentioned, and one of these can be used alone or in combination of two or more. Among these, it is preferable to use a bisphenol A type epoxy resin.

The liquid epoxy resin is not particularly limited as long as it is liquid at room temperature, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak phenol type epoxy resin, and naphthalene type epoxy resin. Can be used alone or in combination of two or more. In particular, from the viewpoint of film tackiness and flexibility, it is preferable to use a bisphenol A type epoxy resin.

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

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

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

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

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

The thermopolymerizable composition preferably contains a film-forming resin. The film-forming resin corresponds to, for example, a high molecular weight resin having an average molecular weight of 10,000 or more, and is preferably having an average molecular weight of about 10,000 to 80,000 from the viewpoint of film formability. Examples of the film-forming resin include various resins such as phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, acrylic resin, polyimide resin and butyral resin, which may be used alone or in combination of two or more. May be used. Among these, it is preferable to preferably use a phenoxy resin from the viewpoint of film formation state, connection reliability and the like.

The thermopolymerizable composition may contain an insulating filler for adjusting the melt viscosity. This includes silica powder and alumina powder. The size of the insulating filler is preferably 20 to 1000 nm in particle size, and the blending amount is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the heat-polymerizable compound (photopolymerizable compound) such as an epoxy compound. ..

Further, a filler, a softener, an accelerator, an antiaging agent, a colorant (pigment, dye), an organic solvent, an ion catcher agent and the like different from the above-mentioned insulating filler may be contained.

Further, if necessary, a stress relaxation agent, a silane coupling agent, an inorganic filler and the like may be blended. Examples of the stress relieving agent include hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer and the like. Examples of the silane coupling agent include epoxy-based, methacryloxy-based, amino-based, vinyl-based, mercapto-sulfide-based, and ureido-based. Examples of the inorganic filler include silica, talc, titanium oxide, calcium carbonate, magnesium oxide and the like.

The insulating resin binder 3 can be formed by forming a coating composition containing the above-mentioned resin into a film by a coating method and drying it, further curing it, or forming a film by a method known in advance. The insulating resin binder 3 may be obtained by laminating a resin layer, if necessary. Further, the insulating resin binder 3 is preferably formed on a release film such as a polyethylene terephthalate film that has been peeled off.

(Viscosity of insulating resin binder)
The minimum melt viscosity of the insulating resin binder 3 can be appropriately determined depending on the method for producing the anisotropic conductive film and the like. For example, as a method for manufacturing an anisotropic conductive film, when conductive particles are held on the surface of an insulating resin binder in a predetermined arrangement and the conductive particles are pushed into the insulating resin binder, the insulating resin binder is used as a film. The minimum melt viscosity of the resin is preferably 1100 Pa · s or more from the viewpoint of enabling molding. Further, as will be described later, a recess 3b is formed around the exposed portion of the conductive particles 2 pushed into the insulating resin binder 3 as shown in FIG. 14 or FIG. 15, and an insulating resin binder is formed as shown in FIG. The minimum melt viscosity is preferably 1500 Pa · s or more, more preferably 2000 Pa · s or more, still more preferably 3000 to 15000 Pa · s, from the viewpoint of forming a dent 3c directly above the conductive particles 2 pushed into 3. It is 3000 to 10000 Pa · s. This minimum melt viscosity is determined using a rotary rheometer (manufactured by TA instruments) as an example, a temperature rise rate of 10 ° C./min, a measurement pressure of 5 g, and a constant measurement plate with a diameter of 8 mm. Can be done. Further, when the step of pushing the conductive particles 2 into the insulating resin binder 3 at preferably 40 to 80 ° C., more preferably 50 to 60 ° C., the temperature is 60 ° C. from the viewpoint of forming the dents 3b or 3c as described above. The lower limit of the viscosity is preferably 3000 Pa · s or more, more preferably 4000 Pa · s or more, further preferably 4500 Pa · s or more, and the upper limit is preferably 20000 Pa · s or less, more preferably 15000 Pa · s or less, and further. It is preferably 10000 Pa · s or less.

By making the viscosity of the resin constituting the insulating resin binder 3 high as described above, the conductive particles 2 are sandwiched between the objects to be connected such as facing electronic parts when the anisotropic conductive film is used. In the case of heating and pressurizing with the above, it is possible to prevent the conductive particles 2 in the anisotropic conductive film from being washed away by the flow of the molten insulating resin binder 3.

(Thickness of insulating resin binder)
The thickness La of the insulating resin binder 3 is preferably 1 μm or more and 60 μm or less, more preferably 1 μm or more and 30 μm or less, and further preferably 2 μm or more and 15 μm or less. Further, the thickness La of the insulating resin binder 3 is preferably a ratio (La / D) of 0.6 to 10 in relation to the average particle diameter D of the conductive particles 2. If the thickness La of the insulating resin binder 3 is too large, the conductive particles are likely to be displaced at the time of anisotropic conductive connection, and the catchability of the conductive particles at the terminal is lowered. This tendency is remarkable when La / D exceeds 10. Therefore, La / D is preferably 8 or less, more preferably 6 or less. On the contrary, if the thickness La of the insulating resin binder 3 is too small and the La / D is less than 0.6, it is difficult to maintain the conductive particles in a predetermined particle dispersion state or a predetermined arrangement by the insulating resin binder 3. Become. In particular, when the terminal to be connected is a high-density COG, the ratio (La / D) of the layer thickness La of the insulating resin binder 3 to the particle diameter D of the conductive particles 2 is preferably 0.8 to 2.

(Embedding of Conductive Particles in Insulating Resin Binder)
The state in which the conductive particles 2 are embedded in the insulating resin binder 3 is not particularly limited, but when an anisotropic conductive film is sandwiched between facing parts and an anisotropic conductive connection is made by heating and pressurizing. As shown in FIGS. 14 and 15, the conductive particles 2 are partially exposed from the insulating resin binder 3 with respect to the tangent plane 3p of the surface 3a of the insulating resin binder 3 in the central portion between the adjacent conductive particles 2. A recess 3b is formed around the exposed portion of the conductive particles 2, or as shown in FIG. 16, the insulating resin binder portion directly above the conductive particles 2 pushed into the insulating resin binder 3 is described above. It is preferable that the recess 3c is formed with respect to the tangent plane 3p similar to the above, and the surface of the insulating resin binder 3 directly above the conductive particles 2 has a swell. With respect to the flattening of the conductive particles 2 that occurs when the conductive particles 2 are sandwiched between the electrodes of the facing electronic components and heated and pressed, the conductive particles 2 are provided with the dents 3b shown in FIGS. 14 and 15. The resistance received from the insulating resin binder 3 is reduced as compared with the case where there is no recess 3b. Therefore, the conductive particles 2 are easily sandwiched between the facing electrodes, and the conduction performance is also improved. Further, among the resins constituting the insulating resin binder 3, the dent 3c (FIG. 16) is formed on the surface of the resin directly above the conductive particles 2, so that the heat and pressure are increased as compared with the case where there is no dent 3c. The pressure at the time tends to be concentrated on the conductive particles 2, the conductive particles 2 are easily pinched by the electrodes, and the conduction performance is improved.

The ratio of the maximum depth Le of the recesses 3b (FIGS. 14 and 15) around the exposed portion of the conductive particles 2 to the average particle diameter D of the conductive particles 2 from the viewpoint of facilitating the effect of the recesses 3b and 3c described above. (Le / D) is preferably less than 50%, more preferably less than 30%, still more preferably 20-25%, and the maximum of the recess 3b (FIGS. 14 and 15) around the exposed portion of the conductive particles 2. The ratio (Ld / D) of the diameter Ld to the average particle diameter D of the conductive particles 2 is preferably 100% or more, more preferably 100 to 150%, and the recess 3c in the resin directly above the conductive particles 2 (FIG. 16). The ratio (Lf / D) of the maximum depth Lf of) to the average particle diameter D of the conductive particles 2 is preferably larger than 0, preferably less than 10%, and more preferably less than 5%.

The diameter Lc of the exposed portion of the conductive particles 2 can be equal to or less than the average particle diameter D of the conductive particles 2, and is preferably 10 to 90% of the particle diameter D. The conductive particles 2 may be exposed at one point on the top 2t of the conductive particles 2, or the conductive particles 2 may be completely buried in the insulating resin binder 3 so that the diameter Lc becomes zero.

(Position of conductive particles in the thickness direction of the insulating resin binder)
The ratio (Lb) of the distance Lb of the deepest part of the conductive particles 2 from the tangent plane 3p (hereinafter referred to as the embedding amount) and the average particle diameter D of the conductive particles 2 from the viewpoint of facilitating the effect of the recess 3b described above. / D) (hereinafter referred to as embedding rate) is preferably 60% or more and 105% or less.

<Insulating adhesive layer>
In the anisotropic conductive film of the present invention, an insulating adhesive layer 4 having a different viscosity and adhesiveness from the resin constituting the insulating resin binder 3 is laminated on the insulating resin binder 3 on which the conductive particles 2 are arranged. May be.

When the above-mentioned recess 3b is formed in the insulating resin binder 3, the insulating adhesive layer 4 has a recess 3b formed in the insulating tree binder 3 as in the anisotropic conductive film 1d shown in FIG. It may be laminated on the surface on which the recess 3b is formed, or may be laminated on the surface opposite to the surface on which the recess 3b is formed, as in the anisotropic conductive film 1e shown in FIG. The same applies when the recess 3c is formed in the insulating resin binder 3. By laminating the insulating adhesive layer 4, when anisotropically conductively connecting electronic components using an anisotropic conductive film, the space formed by the electrodes and bumps of the electronic components is filled and the adhesiveness is improved. Can be done.

Further, when the insulating adhesive layer 4 is laminated on the insulating resin binder 3, the insulating adhesive layer 4 is an IC chip or the like regardless of whether or not the insulating adhesive layer 4 is on the forming surface of the recesses 3b and 3c. It is preferable that the insulating resin binder 3 is on the side of the second electronic component such as a substrate (in other words, the insulating resin binder 3 is on the side of the second electronic component such as a substrate). By doing so, it is possible to avoid unintentional movement of the conductive particles, and it is possible to improve the catchability. Normally, the first electronic component such as an IC chip is on the pressing jig side, the second electronic component such as a substrate is on the stage side, and the anisotropic conductive film is temporarily crimped to the second electronic component, and then the first electron is used. The component and the second electronic component are mainly crimped, but depending on the size of the thermocompression bonding region of the second electronic component, the anisotropic conductive film is temporarily attached to the first electronic component and then the first electronic component and the second electron. This crimp the component.

As the insulating adhesive layer 4, those used as the insulating adhesive layer in a known anisotropic conductive film can be appropriately selected and used. The insulating adhesive layer 4 may be adjusted to have a lower viscosity by using the same resin as the insulating resin binder 3 described above. The minimum melt viscosity between the insulating adhesive layer 4 and the insulating resin binder 3 is such that the space formed by the electrodes and bumps of the electronic components is more likely to be filled with the insulating adhesive layer 4, and the electronic components are bonded to each other. The effect of improving sex can be expected. Further, as this difference increases, the amount of movement of the resin constituting the insulating resin binder 3 becomes relatively small at the time of anisotropic conductive connection, so that the catchability of the conductive particles at the terminals is likely to be improved. Practically, the minimum melt viscosity ratio between the insulating adhesive layer 4 and the insulating resin binder 3 is preferably 2 or more, more preferably 5 or more, still more preferably 8 or more. On the other hand, if this ratio is too large, resin squeeze out or blocking may occur when a long anisotropic conductive film is used as a wound body, so that the ratio is preferably 15 or less in practice. More specifically, the minimum melt viscosity of the insulating adhesive 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.

As a method for forming the insulating adhesive layer 4, a coating composition containing a resin similar to the resin forming the insulating resin binder 3 is formed and dried by a coating method, further cured, or known in advance. It can be formed by forming a film according to the above method.

The thickness of the insulating adhesive layer 4 is preferably 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 15 μm or less.

Further, the minimum melt viscosity of the entire anisotropic conductive film including the insulating resin binder 3 and the insulating adhesive layer 4 depends on the ratio of the thickness of the insulating resin binder 3 and the insulating adhesive layer 4, but is practically May be 8000 Pa · s or less, may be 200 to 7000 Pa · s in order to facilitate filling between bumps, and is preferably 200 to 4000 Pa · s.

Further, an insulating filler such as silica fine particles, alumina, or aluminum hydroxide may be added to the insulating resin binder 3 or the insulating adhesive layer 4 as needed. The blending amount of the insulating filler is preferably 3 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the resin constituting the layer. As a result, even if the anisotropic conductive film is melted during the anisotropic conductive connection, it is possible to prevent the conductive particles from unnecessarily moving due to the melted resin.

<Manufacturing method of anisotropic conductive film>
As a method for producing an anisotropic conductive film, for example, a transfer mold for arranging conductive particles in a predetermined arrangement is manufactured, conductive particles are filled in the recesses of the transfer mold, and the conductive particles are formed on a release film. The conductive particles 2 are transferred to the insulating resin binder 3 by covering the insulating resin binder 3 with the pressure and pushing the conductive particles 2 into the insulating resin binder 3. Alternatively, the insulating adhesive layer 4 is further laminated on the conductive particles 2. In this way, the anisotropic conductive film 1A can be obtained.

Further, after filling the concave portions of the transfer type with conductive particles, an insulating resin binder is put on the concave portions, and the conductive particles are transferred from the transfer type to the surface of the insulating resin binder to insulate the conductive particles on the insulating resin binder. An anisotropic conductive film may be produced by pushing it into a resin binder. The embedding amount (Lb) of the conductive particles can be adjusted by the pressing pressure at the time of pushing, the temperature, and the like. Further, the shape and depth of the recesses 3b and 3c can be adjusted by adjusting the viscosity of the insulating resin binder at the time of pushing, the pushing speed, the temperature and the like. For example, the viscosity of the insulating resin binder when the conductive particles are pushed in is preferably 3000 Pa · s or more, more preferably 4000 Pa · s or more, further preferably 4500 Pa · s or more, and the upper limit is preferably 20000 Pa · s. Hereinafter, it is more preferably 15,000 Pa · s or less, and further preferably 10000 Pa · s or less. Further, such a viscosity is preferably obtained at 40 to 80 ° C, more preferably 50 to 60 ° C. More specifically, in the case of producing the anisotropic conductive film 1a having the recess 3b shown in FIG. 14 on the surface of the insulating resin binder, the viscosity of the insulating resin binder at the time of pushing the conductive particles is 8000 Pa · s ( It is preferably 50 to 60 ° C.), and when the anisotropic conductive film 1c having the recess 3c shown in FIG. 16 is manufactured, the viscosity of the insulating resin binder when the conductive particles are pushed in is 4500 Pa · s (50 to 60 ° C.). 60 ° C.) is preferable.

As the transfer type, in addition to a type in which the concave portion is filled with conductive particles, a type in which a slight adhesive is applied to the top surface of the convex portion so that the conductive particles adhere to the top surface may be used.

These transfer molds can be manufactured by using and applying known techniques such as machining, photolithography, and printing methods.

Further, as a method of arranging the conductive particles in a predetermined arrangement, a method of using a biaxially stretched film or the like may be used instead of the method of using a transfer type.

<Wrapped body>
Since the anisotropic conductive film is continuously used for connecting electronic components, it is preferable to use a film winding body wound on a reel. The length of the film winding body may be 5 m or more, and preferably 10 m or more. Although there is no particular upper limit, it is preferably 5000 m or less, more preferably 1000 m or less, and further preferably 500 m or less from the viewpoint of handleability of the shipped product.

The film winding body may be a film wound body in which an anisotropic conductive film shorter than the total length is connected with a connecting tape. There may be a plurality of connecting points, they may be regularly present, or they may be randomly present. The thickness of the connecting tape is not particularly limited as long as it does not affect the performance, but if it is too thick, it affects the resin squeeze out and blocking, so it is preferably 10 to 40 μm. The width of the film is not particularly limited, but is 0.5 to 5 mm as an example.

According to the film winding body, continuous anisotropic conductive connection can be made, which can contribute to cost reduction of the connection body.

<Connection structure>
In the anisotropic conductive film of the present invention, a first electronic component such as an FPC, an IC chip, and an IC module and a second electronic component such as an FPC, a rigid substrate, a ceramic substrate, a glass substrate, and a plastic substrate are heated or lightly formed. It can be preferably applied when making an anisotropic conductive connection. It is also possible to stack IC chips and IC modules to connect the first electronic components anisotropically and conductively. The connection structure thus obtained and the method for manufacturing the same are also a part of the present invention.

As a method of connecting electronic components using an anisotropic conductive film, for example, the interface on the side of the anisotropic conductive film on the side where conductive particles are close to each other in the film thickness direction is temporarily attached to a second electronic component such as a wiring board. However, it is preferable to mount a first electronic component such as an IC chip on the temporarily bonded anisotropic conductive film and thermocompression bond it from the first electronic component side from the viewpoint of improving connection reliability. It can also be connected using photocuring. In this connection, from the viewpoint of connection work efficiency, it is preferable to align the longitudinal direction of the terminal of the electronic component with the lateral direction of the anisotropic conductive film.

Experimental Example 1 to Experimental Example 8
(Manufacturing anisotropic conductive film)
Regarding the anisotropic conductive film used for COG connection, the influence of the resin composition of the insulating resin binder and the arrangement of the conductive particles on the film forming ability and the conduction characteristics was investigated as follows.

First, an insulating resin binder and a resin composition for forming an insulating adhesive layer were prepared with the formulations shown in Table 1, respectively. In this case, the minimum melt viscosity of the resin composition was adjusted according to the preparation conditions of the insulating resin composition. The resin composition forming the insulating resin binder 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 insulated on the PET film with a thickness of La shown in Table 2. A sex resin binder layer was formed. Similarly, an insulating adhesive layer was formed on the PET film with the thickness shown in Table 2.

Next, the arrangement of the conductive particles in a plan view was as shown in Table 2, and a mold was prepared so that the distance between the centers of the closest conductive particles in the repeating unit was 6 μm. By pouring known transparent resin pellets into the mold in a molten state, cooling and hardening the mold, a resin mold having a dent arranged as shown in Table 2 was formed. Here, in Experimental Example 8, the arrangement of the conductive particles was a six-way lattice arrangement (number density 32000 pieces / mm ² ), and one of the lattice axes was tilted by 15 ° with respect to the longitudinal direction of the anisotropic conductive film. ..

Metal-coated resin particles (Sekisui Chemical Co., Ltd., AUL703, average particle diameter of 3 μm) are prepared as conductive particles, and the conductive particles are filled in a resin mold recess and covered with the above-mentioned insulating resin binder. , 60 ° C., 0.5 MPa to attach. Then, the insulating resin binder is peeled off from the mold, and the conductive particles on the insulating resin binder are pressed into the insulating resin binder by pressurizing (pressing conditions: 60 to 70 ° C., 0.5 MPa), and the insulating resin is pressed. A film was prepared in which conductive particles were embedded in the binder in the state shown in Table 2. In this case, the embedded state of the conductive particles was controlled by the pushing condition. As a result, in Experimental Example 4, the film shape was not maintained after the conductive particles were pushed in, but in other Experimental Examples, a film in which the conductive particles were embedded could be produced. Observation with a metallurgical microscope revealed dents around the exposed portion of the embedded conductive particles or directly above the embedded conductive particles as shown in Table 2. In each experimental example except Experimental Example 4, both a dent around the exposed portion of the conductive particle and a dent directly in front of the conductive particle were observed, but in Table 4, the dent is most clearly shown in each experimental example. The measured values of what was observed are shown.

An anisotropic conductive film having a two-layer resin layer was produced by laminating an insulating adhesive layer on the side of the film in which the conductive particles were embedded. However, in Experimental Example 4, since the film shape was not maintained after the conductive particles were pushed in, the subsequent evaluation was not performed.

(evaluation)
For the anisotropic conductive film of each experimental example, (a) initial conduction resistance and (b) conduction reliability were measured as follows. The results are shown in Table 2.

(A) Initial conduction resistance The anisotropic conductive film of each experimental example is sandwiched between the glass substrate on the stage and the conduction characteristic evaluation IC on the pressing tool side, and heated and pressed by the pressing tool (180 ° C., 5 seconds). ), And each evaluation connection was obtained. In this case, the thrust by the pressing tool was changed to three stages of low (40 MPa), medium (60 MPa), and high (80 MPa) to obtain three types of evaluation connectors.

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

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

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

The initial conduction resistance of the obtained evaluation connection was measured and evaluated according to the following three evaluation criteria.
Evaluation criteria for initial conduction resistance (practically, there is no problem if it is less than 2Ω)
A: Less than 0.4Ω B: 0.4Ω or more and less than 0.8Ω C: 0.8Ω or more

(B) Conduction reliability The evaluation connection made in (a) is placed in a constant temperature bath at a temperature of 85 ° C. and a humidity of 85% RH for 500 hours to perform a reliability test, and the subsequent conduction resistance is the same as the initial conduction resistance. And evaluated according to the following three evaluation criteria.

Evaluation criteria for continuity reliability (practically, there is no problem if it is less than 5Ω)
A: Less than 1.2Ω B: 1.2Ω or more and less than 2Ω C: 2Ω or more

From Table 2, it can be seen that in Experimental Example 4 in which the minimum melt viscosity of the insulating resin layer is 800 Pa · s, it is difficult to form a film having a dent in the insulating resin binder near the conductive particles. On the other hand, in the experimental example in which the minimum melt viscosity of the insulating resin binder was 1500 Pa · s or more, it was possible to form a convex portion in the vicinity of the conductive particles of the insulating resin binder 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. Further, it can be seen that in Experimental Examples 1 to 7 in which the number density of the conductive particles is lower than that in Experimental Example 8 having a 6-way lattice arrangement, anisotropic conductive connection can be performed at a lower voltage.

(C) Short-circuit occurrence rate Using the anisotropic conductive films of Experimental Examples 1 to 3 and 5 to 8, the evaluation is performed under the connection conditions of 180 ° C., 60 MPa, and 5 seconds using the following IC for evaluating the short-circuit occurrence rate. The connection material for evaluation was obtained, the number of shorts of the obtained connection material for evaluation was measured, and the short circuit occurrence rate was obtained as the ratio of the measured number of shorts to the number of terminals of the evaluation IC.

IC for evaluation of short-circuit occurrence rate (7.5 μm space comb tooth TEG (test element group): outer diameter 15 × 13 mm
Thickness 0.5 mm
Bump specifications Size 25 x 140 μm, distance between bumps 7.5 μm, bump height 15 μm

If the short circuit is less than 50 ppm, it is practically preferable, and the anisotropic conductive films of Experimental Examples 1 to 3 and 5 to 8 are all less than 50 ppm.

When the conductive particles captured per bump were measured for each experimental example except Experimental Example 4, 10 or more conductive particles were captured in each of them.

Experimental Examples 9 to 16
(Manufacturing anisotropic conductive film)
Regarding the anisotropic conductive film used for FOG connection, the influence of the resin composition of the insulating resin binder and the arrangement of the conductive particles on the film forming ability and the conduction characteristics was investigated as follows.

That is, a resin composition for forming an insulating resin binder and an insulating adhesive layer was prepared with the formulations shown in Table 3, and an anisotropic conductive film was produced using these in the same manner as in Experimental Example 1. Table 4 shows the arrangement of the conductive particles and the distance between the centers of the closest conductive particles in this case. In Experimental Example 16, the arrangement of the conductive particles was a six-way lattice arrangement (number density 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.

In the process of producing the anisotropic conductive film, the film shape was not maintained in Experimental Example 12 after the conductive particles were pushed into the insulating resin binder, but the film shape was maintained in the other experimental examples. Therefore, the anisotropic conductive film of the experimental examples excluding Experimental Example 12 was measured by observing the embedded state of the conductive particles with a metallurgical microscope, and further evaluation was performed thereafter. Table 4 shows the embedded state of the conductive particles in each experimental example. The embedded state shown in Table 4 is a measured value in which the dent of the insulating resin binder is most clearly observed in each experimental example as in Table 2.

(evaluation)
For the anisotropic conductive film of each experimental example, (a) initial conduction resistance and (b) conduction reliability were measured as follows. The results are shown in Table 4.

(A) Initial conduction resistance The anisotropic conductive film obtained in each experimental example is cut to a size of 2 mm × 40 mm, sandwiched between the FPC for evaluating conduction characteristics and a glass substrate, and heated and pressed with a tool width of 2 mm (180 ° C.). 5 seconds) to obtain each evaluation connection. In this case, the thrust by the pressing tool was changed to three stages of low (3 MPa), medium (4.5 MPa), and high (6 MPa) to obtain three types of evaluation connectors. The conduction resistance of the obtained evaluation connection was measured in the same manner as in Experimental Example 1, and the measured value was evaluated in three stages according to the following criteria.

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

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

Evaluation criteria for initial conduction resistance A: Less than 1.6Ω B: 1.6Ω or more and less than 2.0Ω C: 2.0Ω or more

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

Evaluation criteria for continuity reliability A: Less than 3.0Ω B: 3.0Ω or more and less than 4Ω C: 4.0Ω or more

From Table 4, it can be seen that it is difficult to form a film having a dent in Experimental Example 12 in which the minimum melt viscosity of the insulating resin layer is 800 Pa · s. On the other hand, in the experimental example in which the minimum melt viscosity of the insulating resin layer is 1500 Pa · s or more, a dent can be formed in the vicinity of the conductive particles of the insulating resin binder 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.

(C) Short-circuit occurrence rate The number of short-circuits of the evaluation connection whose initial conduction resistance was measured was measured, and the short-circuit occurrence rate was obtained from the measured number of shorts and the number of gaps of the evaluation connection. If the short circuit occurrence rate is less than 100 ppm, there is no practical problem.
In both Experimental Examples 9 to 11 and 13 to 16, the short circuit occurrence rate was less than 100 ppm.

When the conductive particles captured per bump were measured for each experimental example except Experimental Example 12, 10 or more conductive particles were captured in each of them.

1A, 1Ba, 1Bb, 1Ca, Cb, 1Da, Db, 1Ea, Eb, 1F, 1G, 1H, 1I, 1J, 1K, 1L, 1M, 1a, 1b, 1c, 1d, 1e anisotropic conductive film 2, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2p, 2q, 2r, 2s, 2t, 2u Conductive particles 3 Insulating resin binder 4 Insulating adhesive layer 5, 5B Repeating unit

Claims (10)

An anisotropic conductive film in which conductive particles are arranged in an insulating resin binder.
In a plan view, polygonal repeating units formed by sequentially connecting the centers of a plurality of conductive particles are repeatedly arranged.
An anisotropic conductive film in which the polygon of the repeating unit has an oblique side with the longitudinal direction or the lateral direction of the anisotropic conductive film. The anisotropic conductive film according to claim 1, wherein the repeating unit is arranged on one surface of the anisotropic conductive film. The anisotropic conductive film according to claim 1 or 2, wherein the repeating unit is trapezoidal. The anisotropic conductive film according to any one of claims 1 to 3, wherein each side of the polygon forming the repeating unit is obliquely intersected with the longitudinal direction or the lateral direction of the anisotropic conductive film. The anisotropic conductive film according to any one of 1 to 3, wherein the polygon forming the repeating unit has sides in the longitudinal direction or the lateral direction of the anisotropic conductive film. A claim that when a polygon constituting a repeating unit is inverted around one side of the polygon, one side of the polygon of the repeating unit after the inversion overlaps with one side of the adjacent repeating unit before the inversion. The anisotropic conductive film according to any one of 1 to 5. The anisotropic conductive film according to any one of claims 1 to 6, wherein the conductive particle unit forms a part of a regular polygon. The anisotropic conductive film according to any one of claims 1 to 5, wherein the arrangement of the conductive particles constituting the conductive particle unit overlaps with the vertices of the hexagons when the regular hexagons are arranged without gaps. A connection structure in which the first electronic component and the second electronic component are anisotropically conductively connected by the anisotropic conductive film according to any one of claims 1 to 8. A method of manufacturing a connection structure between a first electronic component and a second electronic component by thermocompression bonding the first electronic component and the second electronic component via an anisotropic conductive film, as an anisotropic conductive film. , A method for manufacturing a connection structure using the anisotropic conductive film according to any one of claims 1 to 8.

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