CN113707361B

CN113707361B - Anisotropic Conductive Film

Info

Publication number: CN113707361B
Application number: CN202110776384.6A
Authority: CN
Inventors: 塚尾怜司; 阿久津恭志
Original assignee: Dexerials Corp
Current assignee: Dexerials Corp
Priority date: 2016-05-05
Filing date: 2017-04-25
Publication date: 2023-08-22
Anticipated expiration: 2037-04-25
Also published as: CN113707361A; TW201812798A; TWI747898B; TW202209356A; TWI823170B; JP2022069456A; WO2017191781A1

Abstract

Provided is an anisotropic conductive film which can correspond to bumps having a narrow pitch and can reduce the number density of conductive particles. In the anisotropic conductive film (1A), conductive particles (2) are arranged in the insulating resin binder (3) as follows. Specifically, a repeating unit (5) of conductive particles is repeatedly arranged on the entire surface of an anisotropic conductive film, wherein the conductive particles (2) are arranged in a row with conductive particles (2 p, 2q, 2 r) having different numbers of conductive particles arranged in parallel at intervals.

Description

Anisotropic conductive film

The application is a divisional application of the following patent application:

the application name is as follows: an anisotropic conductive film; filing date: 25 days of 2017, 4; application number: 201780025115.8.

Technical Field

The present application relates to an anisotropic conductive film.

Background

An anisotropic conductive film in which conductive particles are dispersed in an insulating resin adhesive is widely used for mounting electronic components such as IC chips on wiring boards. In anisotropic conductive films, with the narrowing of pitch of bumps accompanying high-density mounting of electronic components, there is a strong demand for improving the trapping of conductive particles on bumps and avoiding short circuits between adjacent bumps.

In response to such a demand, there has been proposed an anisotropic conductive film in which conductive particles are arranged in a lattice-like arrangement, the arrangement axis is inclined with respect to the longitudinal direction of the anisotropic conductive film, and in this case, the distances between the conductive particles are separated by a predetermined ratio (patent documents 1 and 2). In addition, it has been proposed to form a region where conductive particles are locally dense by connecting conductive particles so as to correspond to a narrow pitch (patent document 3).

Prior art literature

Patent literature

Patent document 1: japanese patent No. 4887700;

patent document 2: japanese patent laid-open No. 9-320345;

patent document 3: japanese patent laid-open No. 2002-519473.

Disclosure of Invention

Problems to be solved by the invention

As described in patent documents 1 and 2, when the conductive particles are arranged in a simple lattice, the layout of the bumps is associated with the inclination angle of the alignment axis or the distance between the conductive particles. Therefore, when the bump is a narrow pitch, the distance between the conductive particles has to be reduced, and it is difficult to avoid a short circuit. In addition, the number density of the conductive particles increases, and the manufacturing cost of the anisotropic conductive film increases.

On the other hand, without reducing the distance between the conductive particles, there is a concern that the conductive particles cannot be captured by the terminals in a sufficient amount.

In addition, in the method of forming a region where conductive particles are locally dense by bonding conductive particles, the risk of short-circuiting becomes high when a plurality of bonded conductive particles enter the inter-bump space at the same time, and therefore, this method is not preferable.

Accordingly, the present invention addresses the problem of providing an anisotropic conductive film that can accommodate bumps having a narrow pitch and that can reduce the number density of conductive particles compared to conventional anisotropic conductive films.

Means for solving the problems

The present inventors have found that when a unit of conductive particles in which conductive particles are arranged in a specific arrangement with a space therebetween is repeatedly arranged over the entire surface of an anisotropic conductive film, a dense region of conductive particles can be formed over the entire surface of the film, and therefore, narrow-pitch bumps can be connected to the dense region of the dense region, and conductive particles are separated from each other in the dense region, and therefore, the risk of short circuit is reduced, and further, the number density of conductive particles in the entire film can be reduced due to the presence of the dense region, and have found the present invention.

That is, the present invention provides an anisotropic conductive film in which conductive particles are arranged in an insulating resin adhesive,

and a repeating unit in which conductive particles having different numbers of conductive particles arranged in parallel are repeatedly arranged, wherein the conductive particles are arranged in a row with a space therebetween.

Effects of the invention

According to the anisotropic conductive film of the present invention, since the repeating units of the conductive particles in a specific particle arrangement are repeatedly arranged without arranging the respective conductive particles in a simple lattice shape, the porous regions of the conductive particles can be formed in the film, and therefore the anisotropic conductive film as a whole can suppress an increase in the number density of the conductive particles. Thus, an increase in manufacturing cost associated with an increase in the number density of the conductive particles can be suppressed. In addition, in general, if the number density of conductive particles increases, the pushing force required to press the jig at the time of anisotropic conductive connection also increases, but according to the anisotropic conductive film of the present invention, by suppressing the increase in the number density of conductive particles, the pushing force required to press the jig at the time of anisotropic conductive connection also is suppressed, so that the electronic component can be prevented from being deformed by anisotropic conductive connection. In addition, since the pushing force of the pushing jig is stabilized without requiring an excessive pushing force, the quality of the conductive characteristics and the like of the anisotropically conductive connected electronic component is stabilized.

On the other hand, according to the anisotropic conductive film of the present invention, since the repeating unit which is a region where conductive particles are dense is formed repeatedly in a vertical and horizontal direction, it is possible to connect bumps with a narrow pitch. Further, since the conductive particles are separated from each other in the repeating unit, even when the repeating unit spans the inter-terminal space, occurrence of a short circuit can be avoided.

Drawings

Fig. 1A is a plan view showing the arrangement of conductive particles of an anisotropic conductive film 1A of the embodiment.

Fig. 1B is a sectional view of an anisotropic conductive film 1A of the embodiment.

Fig. 2 is a plan view of an anisotropic conductive film 1B of the embodiment.

Fig. 3 is a plan view of an anisotropic conductive film 1C of the embodiment.

Fig. 4 is a plan view of an anisotropic conductive film 1D of the embodiment.

Fig. 5 is a plan view of an anisotropic conductive film 1E of the embodiment.

Fig. 6 is a plan view of an anisotropic conductive film 1F of the embodiment.

Fig. 7 is a plan view of an anisotropic conductive film 1G of the embodiment.

Fig. 8 is a plan view of an anisotropic conductive film 1H of the embodiment.

Fig. 9 is a plan view of an anisotropic conductive film 1I of the embodiment.

Fig. 10 is a plan view of an anisotropic conductive film 1J of the embodiment.

Fig. 11 is a plan view of an anisotropic conductive film 1K of the embodiment.

Fig. 12 is a sectional view of an anisotropic conductive film 1a of the embodiment.

Fig. 13 is a sectional view of an anisotropic conductive film 1b of the embodiment.

Fig. 14 is a sectional view of an anisotropic conductive film 1c of the embodiment.

Fig. 15 is a sectional view of an anisotropic conductive film 1d of the embodiment.

Fig. 16 is a sectional view of an anisotropic conductive film 1e of the embodiment.

Detailed Description

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

< integral Structure of Anisotropic conductive film >)

Fig. 1A is a plan view showing the arrangement of conductive particles of an anisotropic conductive film 1A of an embodiment of the present invention, and fig. 1B is a sectional view thereof.

The anisotropic conductive film 1A has such a configuration that: the conductive particles 2 are arranged in a single layer on or near the surface of the insulating resin binder 3, and an insulating adhesive layer 4 is laminated thereon.

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, conductive particles used in a known anisotropic conductive film can be appropriately selected and used. Examples thereof include metal particles of nickel, copper, silver, gold, palladium, and the like; and resin particles in which the surfaces of resin particles such as polyamide and polybenzguanamine are coated with a metal such as nickel. The size of the conductive particles to be disposed is preferably 1 to 30. Mu.m, more preferably 1 μm to 10. Mu.m, still more preferably 2 μm to 6. Mu.m.

The average particle diameter 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 diameter may be measured. In this case, it is preferable to measure 200 or more, more preferably 500 or more, still more preferably 1000 or more.

The surface of the conductive particles 2 is preferably coated with an insulating coating, insulating particle treatment, or the like. Such coating is easily peeled off from the surface of the conductive particle 2 and does not hinder anisotropic conductive connection. In addition, 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% of the conductive particle diameter, more preferably within 10%.

Configuration of conductive particles

(repeating units)

The arrangement of the conductive particles 2 in the plan view of the anisotropic conductive film 1A is such that the repeating units 5 in which the conductive particle rows 2p, 2q, 2r and the parallel individual conductive particles 2s are repeated vertically and horizontally (X direction, Y direction) over the entire surface of the anisotropic conductive film 1A are sequentially connected to each other, and the polygons formed by connecting the centers of the conductive particles constituting the outer shape of the repeating units 5 are triangular. The anisotropic conductive film of the present invention can have a region where no conductive particles are arranged, if necessary.

The conductive particle rows 2p, 2q, 2r are arranged in a straight line with a space therebetween in a plan view. The conductive particle numbers constituting the conductive particle rows 2p, 2q, 2r are gradually different, and the conductive particle rows 2p, 2q, 2r are arranged in parallel. By repeating the arrangement of the particles in parallel of the conductive particle rows 2p, 2q, and 2r having such gradually different particle numbers, the number density of the conductive particles is locally formed to be a hydrophobic density, and therefore even when a minute displacement occurs in the case of attaching the anisotropic conductive film to an electronic component, a stable number of conductive particles can be easily captured in any bump constituting the bump row. This becomes effective in accordance with the case where anisotropic conductive connection is continuously performed. That is, when the anisotropic conductive film is slightly offset from the adhesion of the electronic component due to the simple lattice arrangement, the number of captured particles tends to be scattered particularly at the bump ends due to the presence or absence or degree of misalignment. In order to suppress such scattering, the angle of the lattice arrangement is designed to be inclined with respect to the longitudinal direction of the film (patent document 1 and the like). However, if the bump width or the bump pitch is further narrowed, the effect of tilting the lattice arrangement is limited. In contrast, in the present invention, a hydrophobic density of the number density of the conductive particles is generated in the range of the bump length, so that the conductive particles can be trapped in any portion of the range of the bump length. In other words, the positions where the conductive particles are captured and the positions where the conductive particles are not captured are caused to be generated at the same time at one bump. Thus, if the shapes (areas) of the bumps are the same in any of the bump arrangements, the number of conductive particles captured by the bumps is stabilized by appropriately setting the repetition interval of the repeating units. Therefore, even if a slight misalignment occurs in the adhesion of the anisotropic conductive film, the capturing state of the conductive particles in the bump arrangement of each connector when the connectors are continuously manufactured on the production line becomes easy to be stabilized. In addition, by simultaneously generating a position where conductive particles are captured and a position where conductive particles are not captured in one bump, it can be expected to reduce inspection labor after anisotropic conductive connection or to improve quality management. For example, by simultaneously generating a position where conductive particles are captured and a position where conductive particles are not captured at one bump, comparison of continuously obtained connection bodies can be easily performed when performing indentation inspection after anisotropic conductive connection. Further, since the presence or absence of misalignment in temporarily attaching an anisotropic conductive film to an electronic component in an anisotropic conductive connection process can be compared with each other in connection bodies manufactured continuously, it is expected that improvement matters of a connection device can be easily determined.

The arrangement of the conductive particles 2 in the repeating unit 5 is such that a part of the conductive particles 2 constituting the repeating unit 5 occupy a part of the vertices of each regular hexagon in the case of arranging the regular hexagons without gaps. Alternatively, in the case of arranging regular triangles without gaps, the vertices of the regular triangles and the conductive particles constituting the repeating unit 5 are arranged to overlap. In other words, the remaining arrangement of the conductive particles in which the predetermined lattice points are regularly omitted from the arrangement of the lattice points in which the conductive particles exist in the 6-square lattice arrangement becomes the repeating unit 5. If the conductive particles 2 are arranged at lattice points arranged in 6 lattices in this way, the arrangement of the particles of the repeating unit 5 can be easily recognized, and the design can be easily performed. As described later, the arrangement of the conductive particles in the repeating unit is not limited to the arrangement based on 6 square lattices, and may be based on square lattices or may be based on an arrangement in which regular polygons of octagons or more are arranged in a row in a longitudinal and a lateral direction, and the sides of adjacent regular polygons are superimposed on each other.

(repeating pattern of repeating units)

In the anisotropic conductive film 1A shown in fig. 1A, the repeating units 5 repeat, more specifically, in the X direction, with the repeating units 5 repeating at intervals of the particles within the repeating units 5. In addition, in the Y direction, the repeating unit 5B and the repeating unit 5 of the repeating unit 5 are alternately repeated with a symmetry axis in the Y direction being spaced apart. In this case, it is preferable that the positions of the sides in the longitudinal direction of the anisotropic conductive film overlap with the same positions of the repeating units adjacent to the repeating units when polygons formed by sequentially connecting the centers of the conductive particles constituting the outer shape of the repeating units are projected in the short side direction of the anisotropic conductive film. Since the width direction of the terminal of the electronic component is generally the longitudinal direction of the anisotropic conductive film, when polygons constituting the outer shape of the repeating unit are superimposed as described above, the probability of capturing conductive particles by the terminal of the electronic component is increased. In addition, the long side direction and the short side direction of the anisotropic conductive film may be replaced. This is because the best replacement occurs depending on the terminal layout.

In addition, when considering the repeating unit of the conductive particle 2, the unit of the repeating unit 5 and the repeating unit 5B of which the repeating unit is inverted may be regarded as the repeating unit of the conductive particle, but in the present invention, the repeating unit is a unit in which a plurality of conductive particle rows are juxtaposed, and preferably the unit having the smallest longitudinal and transverse repetition.

(size of repeating unit)

The size of the anisotropic conductive film of the repeating unit 5 or the distance between the repeating units is preferably determined according to the bump width or the size of the inter-bump space of the electronic component connected by the anisotropic conductive film 1A.

For example, when the connection object is a non-fine pitch, the size of the repeating unit 5 in the longitudinal direction of the anisotropic conductive film is preferably smaller than the length of either the bump width or the inter-bump gap. Even with such a size, the repeated arrangement of the repeating units 5 can capture the minimum number of conductive particles necessary for connection of the bump, and the number of conductive particles not involved in connection can be reduced, so that the cost of the anisotropic conductive film can be reduced. In addition, by inclining the sides of the polygon constituting the outline of the repeating unit 5 in the short side direction of the anisotropic conductive film 1A, stable connection performance can be obtained regardless of the cut-out position of the long anisotropic conductive film.

When the connection object is a non-fine pitch, the distance between the adjacent repeating units 5 and 5B in the longitudinal direction of the anisotropic conductive film is preferably shorter than the inter-bump space of the electronic component connected by the anisotropic conductive film.

On the other hand, when the connection object is a fine pitch, it is preferable that the size of the repeating units 5, 5B in the longitudinal direction of the anisotropic conductive film be set to a size that spans the inter-bump space.

Note that, regarding the critical point of the fine pitch and the non-fine pitch, as an example, the bump width may be smaller than 30 μm to be fine pitch, and 30 μm or more to be non-fine pitch.

In the case of determining the size of the repeating unit 5 according to the connection object as described above, the number of conductive particles constituting the repeating unit 5 is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. In general, it is preferable to trap 3 or more, particularly 10 or more conductive particles between opposite terminals connected by anisotropic conductive connection, and for this reason, when the repeating unit is sandwiched between the opposite terminals, it is possible to confirm that the number of conductive particles trapped by the indentation of one repeating unit.

(specific modification of the repeating units)

In the present invention, the arrangement of the conductive particles 2 in the repeating unit 5 or the longitudinal and lateral repeating pitch of the repeating unit 5 can be appropriately changed according to the shape of the terminal or the pitch of the terminal to be connected by anisotropic conductive connection. Thus, the anisotropic conductive film as a whole can achieve higher trapping properties with a smaller number of conductive particles than in the case where the conductive particles 2 are arranged in a simple lattice shape.

For example, in addition to the repeating system shown in fig. 1A, the repeating units 5 may be repeated in a staggered arrangement as in the anisotropic conductive film 1B shown in fig. 2. In the staggered arrangement, since the influence of the resin flow upon the conductive particles during anisotropic conductive connection of the electronic component is different between the bumps located at the central portion of the staggered arrangement and the bumps located at the outer sides, and the risk of short-circuiting between the bumps located at the central portion of the staggered arrangement and the bumps located at the outer sides is also different, the shape of the repeating unit 5 can be appropriately changed to adjust the flow of the resin flow.

The arrangement of the conductive particles 2 in the repeating unit 5 can be changed as appropriate according to the shape of the terminal to be connected by anisotropic conductive connection or the pitch of the terminals. For example, as in the anisotropic conductive film 1C shown in fig. 3, the number of conductive particles constituting the conductive particle row 2p in one repeating unit 5 may be gradually increased or decreased, or individual conductive particles 2s may be repeatedly arranged together with repetition of the repeating unit 5. Further, among 3 conductive particle rows arranged in parallel in one repeating unit, the number of conductive particles constituting the central conductive particle row may be larger or smaller than the number of conductive particles constituting the conductive particle rows on both sides. For example, as in the anisotropic conductive film 1D shown in fig. 4, in each of the repeating units 5, a conductive particle row 2p in which 4 conductive particles 2 are arranged in the longitudinal direction of the anisotropic conductive film, a conductive particle row 2q in which 2 conductive particles are arranged, a conductive particle row 2r in which 3 conductive particles are arranged, and 1 conductive particle 2s are arranged in parallel. If the number of conductive particles in the parallel conductive particle rows in one repeating unit is increased or decreased, the outer shape of the repeating unit is a complex polygonal shape, and it is easy to cope with the connection of radial bump arrangements (so-called fan-out bumps). When the arrangement of the conductive particles in one repeating unit is represented by the number of conductive particles constituting the conductive particle row of the repeating unit, for example, when the repeating unit shown in fig. 4 is represented by [4-2-3-1], examples of variations of the repeating unit include [4-1-4-1], [4-3-1-2], [3-2-2-1], [4-1-2-3], and [4-2-1-3 ]. These may be combined to repeat the configuration. Examples thereof include [4-2-3-1-2-1-4-3].

The distance between the conductive particles in one conductive particle row may be the same as or different from each other in the parallel conductive particle row in one repeating unit. For example, as in the anisotropic conductive film 1E shown in fig. 5, the repeating unit 5 may have a diamond shape and the conductive particles 2 may be disposed at the center thereof. In the repeating unit, a conductive particle row 2m composed of 5 conductive particles, a conductive particle row 2n composed of 2 conductive particles, a conductive particle row 2o composed of 3 conductive particles, a conductive particle row 2p composed of 2 conductive particles, and a conductive particle row 2q composed of 5 conductive particles are arranged in parallel, and the inter-conductive particle distances in the conductive particle rows 2m, 2q, the inter-conductive particle distances in the conductive particle rows 2n, 2p, and the inter-conductive particle distances in the conductive particle row 2o are different from each other. When this is represented by [4-3-2-1] in the above table, the arrangement of the conductive particles at the center of the missing 3 may be used. This is because the risk of occurrence of short circuits can be further reduced.

In the anisotropic conductive films 1A, 1B, 1C, 1D, and 1E described above, the arrangement of the conductive particles 2 in the repeating units 5 and 5B is present at lattice points of 6 square lattices, but the parallel conductive particle rows 2p may be arranged based on square lattices as in the anisotropic conductive film 1F shown in fig. 6.

The anisotropic conductive film 1G shown in fig. 7 is configured such that a repeating unit 5 composed of 2 rows of conductive particles 2p and 2q and a repeating unit 5B for rotating the arrangement axis of the conductive particles of the repeating unit 5 by 60 ° are repeatedly arranged over the entire surface of the film. In this way, a certain repeating unit and a repeating unit that rotates at a predetermined angle may be used in combination.

As the shape of the repeating unit, a polygon formed by sequentially connecting conductive particles constituting the outer shape thereof may be a regular polygon. This makes it easy to identify the arrangement of the conductive particles, and is therefore preferable. In this case, each conductive particle forming the repeating unit may not exist in a lattice point of 6 square lattices or square lattices. For example, the outer shape of the repeating unit 5 can be formed into a regular octagon as in the anisotropic conductive film 1H shown in fig. 8. In this case, the conductive particles constituting the outer shape of the repeating unit are arranged at the vertices of regular octagons of a lattice in which the sides of the adjacent regular octagons are overlapped with each other in a vertically and horizontally aligned regular octagons, as shown by the broken line. The conductive particles may be disposed at the vertices of a regular polygon having a regular dodecagon shape or more. Further, the conductive particles may be arranged at lattice points of 6 square lattices or square lattices to form a repeating unit having a substantially regular polygon with an outline of an octagon or more. For example, the repeating unit 5 of the anisotropic conductive film 1I shown in fig. 9 is formed of the conductive particles 2 arranged at lattice points of a square lattice, and is formed into an octagon shape symmetrical in both the long-side direction and the short-side direction of the anisotropic conductive film. This makes it possible to easily identify the arrangement of the conductive particles.

The parallel conductive particle rows in the repeating unit may not be parallel to each other, but may be radially arranged. For example, as in the anisotropic conductive film 1J shown in fig. 10, the repeating unit 5 having the conductive particle rows 2m, 2n, 2o, 2p, 2q arranged in a radial pattern can be arranged vertically and horizontally repeatedly. In this case, the conductive particles 2 may not be present at lattice points of 6 square lattices or square lattices.

(orientation of the sides of the repeating units)

Among the anisotropic conductive films described above, for example, in the anisotropic conductive film 1A shown in fig. 1A, each side of the triangle 5x formed by sequentially connecting the centers of the conductive particles constituting the outer shape of the repeating unit 5 is diagonally crossed with the long side direction or the short side direction of the anisotropic conductive film 1A. Thus, the outer tangent L1 of the conductive particle 2a in the longitudinal direction of the anisotropic conductive film penetrates the conductive particle 2b adjacent to the conductive particle 2a in the longitudinal direction of the anisotropic conductive film. Further, an outer tangent L2 to the conductive particles 2a in the short side direction of the anisotropic conductive film penetrates the conductive particles 2c adjacent to the conductive particles 2a in the short side direction of the anisotropic conductive film. In general, in anisotropic conductive connection, since the long side direction of the anisotropic conductive film becomes the short side direction of the bump, when the sides of the polygon 5x of the repeating unit 5 are diagonally crossed with the long side direction or the short side direction of the anisotropic conductive film 1A, the plurality of conductive particles can be prevented from being aligned in a straight line along the edge of the bump, and thus the phenomenon that the plurality of conductive particles aligned in a straight line are gathered and separated from the terminal and do not contribute to conduction can be avoided, and therefore the capturing property of the conductive particles 2 can be improved.

In addition, in the case where the long side direction of the anisotropic conductive film becomes the short side direction of the bump at the time of anisotropic conductive connection, the polygon 5x formed of the conductive particles constituting the outer shape of the repeating unit 5 may not necessarily have all sides thereof inclined with the long side direction or the short side direction of the anisotropic conductive film, but from the viewpoint of the capturing property of the conductive particles, it is preferable to incline 2 sides or more, more preferably 3 sides or more with the long side direction or the short side direction of the anisotropic conductive film.

On the other hand, when the arrangement pattern of the bumps is radial (so-called fanout bumps), the polygon constituting the repeating unit preferably has sides in the long-side direction or the short-side direction of the anisotropic conductive film. That is, in order to prevent the bumps to be connected from being displaced by thermal expansion of the base material on which the bumps are provided, the bump arrangement pattern may be made radial (for example, japanese unexamined patent publication No. 2007-19550, 2015-232660, etc.), and in this case, the angle formed by the longitudinal direction of each bump and the longitudinal direction of the anisotropic conductive film gradually changes. Therefore, even if the sides of the polygon of the repeating unit 5 are not inclined with respect to the long side direction or the short side direction of the anisotropic conductive film, the sides of the polygon of the repeating units 5, 5B are inclined with respect to the long side edges of the respective bumps arranged in a radial pattern. Therefore, most of the conductive particles associated with the edge of the bump are not trapped by the bump during anisotropic conductive connection, and the trapping property of the conductive particles is reduced. On the other hand, the radial arrangement pattern of the bumps is usually formed symmetrically. Therefore, from the viewpoint of easy confirmation of the connection state by the indentation after anisotropic conductive connection, it is preferable to provide the polygon constituting the outer shape of the repeating unit 5 with sides in the long side direction or short side direction of the anisotropic conductive film. Therefore, for example, in the case where the repeating unit is formed in the same triangle as the anisotropic conductive film 1A shown in fig. 1A, it is preferable that the triangle 1 side 5a constituting the outer shape of the repeating unit 5 is arranged parallel to the long side direction or the short side direction of the anisotropic conductive film as in the anisotropic conductive film 1K shown in fig. 11. As in the repeating unit 5 of the anisotropic conductive film 1H shown in fig. 8, the anisotropic conductive film may have a side 5a parallel to the longitudinal direction and a side 5b parallel to the lateral direction.

The arrangement of the conductive particles in the present invention is not limited to the arrangement of the repeating units shown in the drawings. For example, the illustrated arrangement may be tilted. In this case, the mode of 90 ° inclination, that is, the long side direction and the short side direction of the film are replaced is also included. The interval of the repeating units 5 or the interval of the conductive particles in the repeating units may be changed.

< nearest inter-particle distance of conductive particles >

The distance between the nearest conductive particles is preferably 0.5 times or more the average conductive particle diameter, both between the conductive particles adjacent to each other in the repeating unit 5 and between the conductive particles adjacent to each other in the repeating unit 5. The distance between the repeating units 5 is preferably longer than the distance between adjacent conductive particles within the repeating units 5. If the distance is too short, short-circuiting is likely to occur due to contact of the conductive particles with each other. The upper limit of the distance between adjacent conductive particles is determined according to the bump shape or bump pitch. For example, when the bump width is 200 μm and the inter-bump gap is 200 μm, if 1 conductive particle is present at the minimum on either the bump width or the inter-bump gap, the distance between the conductive particles is made smaller than 400 μm. From the viewpoint of making the capturing property of the conductive particles reliable, it is preferably less than 200 μm.

< number Density of conductive particles >)

In the case where the average particle diameter of the conductive particles is smaller than 10 μm, the number density of the conductive particles is excellent from the viewpoint of suppressing the manufacturing cost of the anisotropic conductive film and not excessively increasing the pushing force required for the pressing jig used in anisotropic conductive connectionSelected to be 50000/mm ² Hereinafter, it is more preferably 35000 pieces/mm ² Hereinafter, it is more preferably 30000 pieces/mm ² The following is given. On the other hand, if the number density of the conductive particles is too low, the conductive particles may not be sufficiently captured at the terminal to cause conduction failure, and thus 300 particles/mm are preferable ² The above, more preferably 500 pieces/mm ² The above, more preferably 800 pieces/mm ² The above.

In addition, when the average particle diameter of the conductive particles is 10 μm or more, it is preferably 15 particles/mm ² The above is more preferably 50 pieces/mm ² The above is more preferably 160 pieces/mm ² The above. This is because if the conductive particle diameter becomes large, the occupation area ratio of the conductive particles also becomes high. For the same reason, 1800 pieces/mm are preferable ² Hereinafter, more preferably 1100 pieces/mm ² Hereinafter, more preferably 800 pieces/mm ² The following is given.

The number density of the conductive particles may be locally (200 μm×200 μm, as an example), or may be other than the number density range.

< insulating resin adhesive >)

The insulating resin binder 3 may be a heat-polymerizable composition, a photopolymerizable composition, a photo-thermal and polymerizable composition used in combination as an insulating resin binder in a known anisotropic conductive film. Among them, as the thermally polymerizable composition, there can be mentioned a thermally radical polymerizable resin composition containing an acrylate compound and a thermal radical polymerization initiator; a thermal cationic polymerizable resin composition comprising an epoxy compound and a thermal cationic polymerization initiator; the photo-polymerizable composition may be a photo-radical polymerizable resin composition containing an acrylate compound and a photo-radical polymerization initiator. In particular, if no problem arises, a plurality of polymerizable compositions may be used in combination. Examples of the use thereof include use of a combination of a hot cationic polymerizable composition and a hot radical polymerizable composition.

Here, as the photopolymerization initiator, a plurality of photopolymerization initiators that react with light of different wavelengths may be contained. Thus, the wavelength used for photocuring of the resin constituting the insulating resin layer in the production of the anisotropic conductive film and the wavelength used for photocuring of the resin for bonding the electronic components to each other in the anisotropic connection can be used separately.

In the case of forming the insulating resin binder 3 using the photopolymerizable composition, all or a part of the photopolymerizable compound contained in the insulating resin binder 3 can be photocured by photocuring at the time of manufacturing the anisotropic conductive film. By this photocuring, the arrangement of the conductive particles 2 in the insulating resin binder 3 is held or fixed, and there is a prospect of suppressing short-circuiting and improving trapping. In addition, by adjusting the conditions of the photo-curing, the viscosity of the insulating resin layer in the process of manufacturing the anisotropic conductive film can be adjusted.

The amount of the photopolymerizable compound blended in the insulating resin binder 3 is preferably 30 mass% or less, more preferably 10 mass% or less, and still more preferably less than 2 mass%. This is because if the photopolymerizable compound is too much, the pushing force required for pressing in at the time of anisotropic conductive connection is increased.

On the other hand, the heat-polymerizable composition contains a heat-polymerizable compound and a heat-polymerizable initiator, but as the heat-polymerizable compound, a compound that also functions as a photo-polymerizable compound may be used. The photopolymerizable composition may contain a photopolymerizable compound and a photopolymerization initiator, separately from the thermally polymerizable compound. It is preferable that the photopolymerizable compound and the photopolymerization initiator are contained differently from the thermally polymerizable 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 photo radical initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerization compound. The insulating adhesive 3 may be made to contain a cured product of these polymerizable compositions.

As the acrylate compound used as the heat-or light-polymerizable compound, conventionally known heat-polymerizable (meth) acrylate monomers can be used. For example, a monofunctional (meth) acrylate monomer or a difunctional or more polyfunctional (meth) acrylate monomer can be used.

The epoxy compound used as the polymerizable compound preferably has a three-dimensional network structure, and is excellent in heat resistance and adhesion, and is used in combination with a solid epoxy resin and a liquid epoxy resin. Herein, the solid epoxy resin means an epoxy resin that is solid at normal temperature. The liquid epoxy resin is an epoxy resin that is liquid at normal temperature. The normal temperature means a temperature range of 5 to 35℃defined by JIS Z8703. In the present invention, two or more epoxy compounds can be used in combination. In addition, an oxetane compound may be used in combination in addition to the epoxy compound.

The solid epoxy resin is not particularly limited as long as it is compatible with a liquid epoxy resin and is solid at ordinary temperature, and examples thereof include bisphenol a type epoxy resin, bisphenol F type epoxy resin, multifunctional epoxy resin, dicyclopentadiene type epoxy resin, phenol formaldehyde type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and the like, and one kind of epoxy resin or two or more kinds of epoxy resins may be used singly or in combination. Among these, bisphenol a type epoxy resins are preferably used.

The liquid epoxy resin is not particularly limited as long as it is liquid at ordinary temperature, and examples thereof include bisphenol a type epoxy resin, bisphenol F type epoxy resin, phenol formaldehyde type epoxy resin, naphthalene type epoxy resin, and the like, and one or two or more of them may be used singly or in combination. In particular, bisphenol a type epoxy resin is preferably used from the viewpoints of adhesiveness, flexibility and the like of the film.

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

The amount of the thermal radical polymerization initiator used is preferably 2 to 60 parts by mass, more preferably 5 to 40 parts by mass, based on 100 parts by mass of the (meth) acrylate compound, since the curing failure occurs when the amount is too small and the product life decreases when the amount is too large.

As the thermal cationic polymerization initiator, an initiator known as a thermal cationic polymerization initiator of an epoxy compound can be used, and for example, an iodonium salt, a sulfonium salt, a quaternary phosphonium salt, ferrocenes, or the like that generates oxygen by heat can be used, and in particular, an aromatic sulfonium salt that exhibits good latency with respect to temperature can be preferably used.

The amount of the thermal cationic polymerization initiator used is preferably 2 to 60 parts by mass, more preferably 5 to 40 parts by mass, based on 100 parts by mass of the epoxy compound, since the curing tends to be poor and the lifetime of the product tends to be reduced in the case of too small an amount.

As the thermoanionic polymerization initiator, a conventionally used known initiator can be used. Examples thereof include organic acid dihydrazide, dicyandiamide, amine-based compounds, polyamidoamine-based (polyamidoamine) compounds, cyanate-based compounds, phenolic resins, acid anhydrides, carboxylic acids, tertiary amine-based compounds, imidazoles, lewis acids, brphi nsted acid salts, polythiol-based curing agents, urea resins, melamine resins, isocyanate compounds, blocked isocyanate compounds, and the like, and one or two or more of these may be used singly or in combination. Among these, a microcapsule-type latent curing agent having an imidazole-modified product as a core and a polyurethane coating the surface thereof is preferably used.

The thermally polymerizable composition preferably contains a film-forming resin. The film-forming resin is, for example, a high molecular weight resin having an average molecular weight of 10000 or more, and preferably has an average molecular weight of about 10000 to 80000 from the viewpoint of film formability. Examples of the film-forming resin include various resins such as phenoxy resin, polyester resin, polyurethane resin, polyester polyurethane resin, acryl resin, polyimide resin, and butyral resin, and these resins may be used alone or in combination of two or more. Among these, phenoxy resins are preferably used appropriately from the viewpoints of film formation state, connection reliability, and the like.

In order to adjust the melt viscosity, the heat-polymerizable composition may contain an insulating filler. Examples of the material include silica powder and alumina powder. The size of the insulating filler is preferably 20 to 1000nm in particle diameter, and the blending amount is preferably 5 to 50 parts by mass per 100 parts by mass of the thermally polymerizable compound (photopolymerizable compound) such as an epoxy compound.

Further, the insulating filler may contain a filler, a softener, an accelerator, an antioxidant, a colorant (pigment, dye), an organic solvent, an ion scavenger, and the like, which are different from the insulating filler.

If necessary, a stress buffer, a silane coupling agent, an inorganic filler, and the like may be blended. Examples of the stress buffer include hydrogenated styrene butadiene block copolymers and hydrogenated styrene isoprene block copolymers. Further, examples of the silane coupling agent include epoxy compounds, methacryloxy compounds, ammonia compounds, vinyl compounds, mercapto/sulfide compounds, and urea compounds. Examples of the inorganic filler include silica, talc, titanium oxide, calcium carbonate, and magnesium oxide.

The insulating resin binder 3 can be formed by forming a coating composition containing the above resin by a coating method, drying the coating composition, further curing the coating composition, or forming a film by a known method in advance. The insulating resin adhesive 3 may be obtained by laminating resin layers as necessary. The insulating resin adhesive 3 is preferably formed on a release film such as a polyethylene terephthalate film subjected to a release treatment.

(viscosity of insulating resin adhesive)

The minimum melt viscosity of the insulating resin binder 3 can be appropriately determined according to the method for producing the anisotropic conductive film, and the like. For example, as a method for producing an anisotropic conductive film, when conducting a method of holding conductive particles on the surface of an insulating resin adhesive in a predetermined arrangement and pressing the conductive particles into the insulating resin adhesive, the minimum melt viscosity of the resin of the insulating resin adhesive is preferably 1100Pa and s or more in terms of being able to form a film. As will be described later, the lowest melt viscosity is preferably 1500Pa or more, more preferably 2000Pa or more, still more preferably 3000 to 15000Pa s, particularly 3000 to 10000Pa s, in that the recess 3b is formed around the exposed portion of the conductive particle 2 pressed into the insulating resin binder 3 as shown in fig. 12 or 13, or the recess 3c is formed right above the conductive particle 2 pressed into the insulating resin binder 3 as shown in fig. 14. As an example, the minimum melt viscosity can be obtained by using a rotary rheometer (manufactured by TA instruments) at a temperature rising rate of 10 ℃/min and a measurement pressure of 5g, and using a measurement plate having a diameter of 8 mm. In the case where the step of pressing the insulating resin binder 3 into the conductive particles 2 is preferably performed at 40 to 80 ℃, more preferably at 50 to 60 ℃, the lower limit of the viscosity at 60 ℃ is preferably 3000Pa s or more, more preferably 4000Pa s or more, still more preferably 4500Pa s or more, the upper limit is preferably 20000Pa s or less, more preferably 15000Pa s or less, still more preferably 10000Pa s or less, from the viewpoint of forming the concave portion 3b or 3c as described above.

By setting the viscosity of the resin constituting the insulating resin adhesive 3 to be high as described above, it is possible to prevent the conductive particles 2 in the anisotropic conductive film from flowing due to the flow of the melted insulating resin adhesive 3 when the anisotropic conductive film is used and the conductive particles 2 are sandwiched between the objects to be connected such as the electronic parts facing each other and heated and pressurized.

(thickness of insulating resin adhesive)

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 still more preferably 2 μm or more and 15 μm or less. In addition, the thickness La of the insulating resin binder 3 is preferably set to 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 during anisotropic conductive connection, and the trapping property of the conductive particles on the terminals is lowered. This tendency is remarkable when La/D exceeds 10. Therefore, la/D is preferably 8 or less, and more preferably 6 or less. Conversely, if the thickness La of the insulating resin binder 3 is too small and La/D is smaller than 0.6, it is difficult to maintain the conductive particles in a predetermined particle-dispersed state or a predetermined arrangement by the insulating resin binder 3. In particular, when the terminal to be connected is 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.

(method of embedding conductive particles in insulating resin adhesive)

The embedded state of the conductive particles 2 in the insulating resin adhesive 3 is not particularly limited, but when the anisotropic conductive film is sandwiched between the opposing members and the anisotropic conductive connection is performed by heating and pressurizing, as shown in fig. 12 and 13, it is preferable that the conductive particles 2 are partially exposed from the insulating resin adhesive 3, and the recesses 3b are formed around the exposed portions of the conductive particles 2 with respect to the tangential plane 3p of the surface 3a of the insulating resin adhesive in the central portion between the adjacent conductive particles 2, or, as shown in fig. 14, the recesses 3c are formed with respect to the tangential plane 3p as described above in the insulating resin adhesive portion directly above the conductive particles 2 pressed into the insulating resin adhesive 3, so that the surface of the insulating resin adhesive 3 directly above the conductive particles 2 has undulation. Since the recesses 3b shown in fig. 12 and 13 are provided for flattening the conductive particles 2 generated when the conductive particles 2 are sandwiched between the electrodes of the opposing electronic components and heated and pressurized, the resistance of the conductive particles 2 from the insulating resin adhesive 3 is reduced as compared with the case where the recesses 3b are not provided. Therefore, the conductive particles 2 are easily sandwiched between the opposing electrodes, and the conduction performance is also improved. Further, by forming the concave portion 3c (fig. 14) on the surface of the resin directly above the conductive particle 2 among the resins constituting the insulating resin binder 3, the pressure at the time of heating and pressurizing is easily concentrated on the conductive particle 2 and the conductive particle 2 is easily sandwiched in the electrode, as compared with the case where the concave portion 3c is not present, thereby improving the conduction performance.

From the viewpoint of easy obtaining of the effects of the above-described recesses 3b, 3c, the ratio (Le/D) of the maximum depth Le of the recess 3b (fig. 12, 13) around the exposed portion of the conductive particle 2 to the average particle diameter D of the conductive particle 2 is preferably less than 50%, more preferably less than 30%, still more preferably 20 to 25%, while the ratio (Ld/D) of the maximum diameter Ld of the recess 3b (fig. 12, 13) around the exposed portion of the conductive particle 2 to the average particle diameter D of the conductive particle 2 is preferably 100% or more, more preferably 100 to 150%, and the ratio (Lf/D) of the maximum depth Lf of the recess 3c (fig. 14) in the resin directly above the conductive particle 2 to the average particle diameter D of the conductive particle 2 is preferably more than 0, and preferably less than 10%, more preferably less than 5%.

The diameter Lc of the exposed portion of the conductive particles 2 can be set to be equal to or smaller than the average particle diameter D of the conductive particles 2, and preferably 10 to 90% of the average particle diameter D. The conductive particles 2 may be completely embedded in the insulating resin binder 3 so that the diameter Lc becomes zero, or 1 point at the top 2t of the conductive particles 2 may be exposed.

(position of conductive particles in the thickness direction of the insulating resin adhesive)

From the viewpoint of easily obtaining the effect of the concave portion 3b, the ratio (Lb/D) (hereinafter, referred to as the embedding rate) of the distance Lb from the deepest portion of the conductive particles 2 (hereinafter, referred to as the embedding amount) from the tangential plane 3p of the surface 3a of the insulating resin adhesive in the central portion between the adjacent conductive particles 2 to the average particle diameter D of the conductive particles 2 is preferably 60% to 105%.

< insulating adhesive layer >)

In the anisotropic conductive film of the present invention, the insulating adhesive layer 4 having a viscosity or adhesiveness different from that of the resin constituting the insulating resin adhesive 3 may be laminated on the insulating resin adhesive 3 on which the conductive particles 2 are disposed.

In the case where the recess 3b is formed in the insulating resin adhesive 3, the insulating adhesive layer 4 may be laminated on the surface of the insulating resin adhesive 3 where the recess 3b is formed, as in the anisotropic conductive film 1d shown in fig. 15, or on the surface opposite to the surface on which the recess 3b is formed, as in the anisotropic conductive film 1e shown in fig. 16. The same applies to the case where the recess 3c is formed in the insulating resin binder 3. When the electronic component is anisotropically connected by the lamination of the insulating adhesive layer 4 by the anisotropic conductive film, the gap formed by the electrode or the bump of the electronic component is filled, and the adhesion can be improved.

In addition, when the insulating adhesive layer 4 is laminated on the insulating resin adhesive 3, the insulating adhesive layer 4 is preferably located on the 1 st electronic component side of the IC chip or the like (in other words, the insulating resin adhesive 3 is located on the 2 nd electronic component side of the substrate or the like) regardless of whether or not the insulating adhesive layer 4 is on the formation surface of the concave portions 3b, 3 c. Thus, the movement of the conductive particles is prevented, and the trapping property can be improved. In general, the 1 st electronic component such as an IC chip is set to the pressing jig side, and the 2 nd electronic component such as a substrate is set to the stage side, and after the anisotropic conductive film and the 2 nd electronic component are temporarily bonded, the 1 st electronic component and the 2 nd electronic component are formally bonded, but because of the size of the thermocompression bonding region of the 2 nd electronic component, etc., the anisotropic conductive film and the 1 st electronic component are temporarily bonded, and then the 1 st electronic component and the 2 nd electronic component are formally bonded.

The insulating adhesive layer 4 can be appropriately selected from known anisotropic conductive films and used as an adhesive layer of an insulating adhesive layer. The insulating adhesive layer 4 may be formed of the same resin as the insulating resin adhesive 3 described above to have a lower viscosity. The effect of improving the adhesion between the electronic components can be expected by filling the voids formed by the electrodes or bumps of the electronic components with the insulating adhesive layer 4 more easily as the lowest melt viscosities of the insulating adhesive layer 4 and the insulating resin adhesive 3 are different. Further, the amount of movement of the resin constituting the insulating resin adhesive 3 during anisotropic conductive connection becomes relatively smaller as the difference increases, so that the capturing of the conductive particles on the terminal becomes easier to improve. In practical use, the lowest melt viscosity ratio of the insulating adhesive layer 4 and the insulating resin binder 3 is preferably 2 or more, more preferably 5 or more, and still more preferably 8 or more. On the other hand, if the ratio is too large, in the case of forming a long anisotropic conductive film into a package, there is a concern that extrusion or clogging of the resin may occur, and therefore, in practical use, it is preferably 15 or less. The insulating adhesive layer 4 preferably has a minimum melt viscosity, more specifically, the ratio is 3000Pa seed s or less, more preferably 2000Pa seed s or less, and particularly 100 to 2000Pa seed s.

As a method for forming the insulating adhesive layer 4, a coating composition containing the same resin as the resin for forming the insulating resin binder 3 can be formed into a film by a coating method, and dried or further cured, or formed into a film by a known method in advance.

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

The minimum melt viscosity of the entire anisotropic conductive film obtained by bonding the insulating resin adhesive 3 and the insulating adhesive layer 4 together depends on the ratio of the thicknesses of the insulating resin adhesive 3 and the insulating adhesive layer 4, but may be 8000Pa s or less in practical use, 200 to 7000Pa s, and preferably 200 to 4000Pa s for the convenience of filling between bumps.

If necessary, an insulating filler such as silica particles, alumina, aluminum hydroxide, or the like may be added to the insulating resin binder 3 or the insulating adhesive layer 4. The amount of the insulating filler to be blended is preferably 3 parts by mass or more and 40 parts by mass or less relative to 100 parts by mass of the resin constituting the layers. Thus, even when the anisotropic conductive film is melted during anisotropic conductive connection, wasteful movement of the conductive particles due to the melted resin can be suppressed.

Method for producing anisotropic conductive film

As a method for producing an anisotropic conductive film, for example, a transfer mold for disposing conductive particles in a predetermined arrangement is produced, the conductive particles are filled into recesses of the transfer mold, an insulating resin adhesive 3 formed on a release film is covered thereon, pressure is applied, and the conductive particles 2 are pressed into the insulating resin adhesive 3, whereby the conductive particles 2 are transferred to the insulating resin adhesive 3. Or further laminating an insulating adhesive layer 4 on the conductive particles 2. Thus, the anisotropic conductive film 1A can be obtained.

Further, after filling the concave portion of the transfer mold with the conductive particles, the conductive particles may be covered with an insulating resin adhesive, the conductive particles may be transferred from the transfer mold to the surface of the insulating resin adhesive, and the conductive particles on the insulating resin adhesive may be pressed into the insulating resin adhesive, thereby manufacturing the anisotropic conductive film. The embedding amount (Lb) of the conductive particles can be adjusted by the pressing force, temperature, and the like at the time of the pressing. The shape and depth of the recesses 3b and 3c can be adjusted by the viscosity, press-in speed, temperature, and the like of the insulating resin adhesive at the time of press-in. For example, the viscosity of the insulating resin binder at the time of pressing in the conductive particles is preferably set to a lower limit of 3000Pa, s or more, more preferably 4000Pa, s or more, still more preferably 4500Pa, s or more, and is preferably set to an upper limit of 20000Pa, s or less, more preferably 15000Pa, s or less, still more preferably 10000Pa, s or less. Further, such a viscosity is preferably obtained at 40 to 80 ℃, more preferably 50 to 60 ℃. More specifically, in the case of manufacturing the anisotropic conductive film 1a having the concave portion 3b shown in fig. 12 on the surface of the insulating resin adhesive, it is preferable that the viscosity of the insulating resin adhesive at the time of pressing in the conductive particles is 8000pa—s (50 to 60 ℃) and in the case of manufacturing the anisotropic conductive film 1c having the concave portion 3c shown in fig. 14, the viscosity of the insulating resin adhesive at the time of pressing in the conductive particles can be 4500pa—s (50 to 60 ℃).

In addition to filling the concave portions with conductive particles, a micro-adhesive may be applied to the top surfaces of the convex portions to adhere the conductive particles to the top surfaces of the convex portions.

These transfer molds can be manufactured using or applying known techniques such as machining, photolithography, printing, and the like.

In addition, as a method of disposing the conductive particles in a predetermined arrangement, a method using a biaxial stretching film or the like may be used instead of the method using a transfer mold.

< package >

For continuous connection to electronic components, the anisotropic conductive film is preferably formed as a film package wound on a reel. The length of the film package may be 5m or more, and preferably 10m or more. Although there is no particular upper limit, from the viewpoint of handling of the shipment, it is preferably 5000m or less, more preferably 1000m or less, and still more preferably 500m or less.

The film package may be formed by connecting an anisotropic conductive film shorter than the entire length thereof with a connecting tape. The connection sites may be present in a plurality of places, may be present regularly, or may be present randomly. The thickness of the connecting tape is not particularly limited as long as it does not inhibit the performance, but too thick may affect the extrusion and clogging of the resin, and is therefore preferably 10 to 40 μm. The width of the film is not particularly limited, but is, as an example, 0.5 to 5mm.

According to the film package, continuous anisotropic conductive connection can be performed, and cost reduction of the connection body can be facilitated.

Connection structure

The anisotropic conductive film of the present invention can be preferably applied to the case where the 1 st electronic component such as FPC, IC chip, IC module, etc. and the 2 nd electronic component such as FPC, hard substrate, ceramic substrate, glass substrate, plastic substrate, etc. are anisotropically connected by heat or light. Further, IC chips or IC modules may be stacked and the 1 st electronic components may be anisotropically connected to each other by conduction. The connection structure thus obtained and the method for producing the same are also part of the present invention.

As a method for connecting electronic components using an anisotropic conductive film, for example, it is preferable to temporarily adhere an interface on a side where conductive particles exist in the film thickness direction of the anisotropic conductive film to a 2 nd electronic component such as a wiring board mounted on a stage, in terms of improving connection reliability, and to thermally press-bond a 1 st electronic component such as an IC chip to the temporarily adhered anisotropic conductive film by using a pressing jig from the 1 st electronic component side. The same connection of electronic components can also be performed by photo-curing.

In addition, when it is difficult to temporarily attach an anisotropic conductive film to a 2 nd electronic component such as a wiring board, because of the size of a connection region of the 2 nd electronic component, etc., the 1 st electronic component of an IC chip mounted on a stage is temporarily attached with the anisotropic conductive film, and then the 1 st electronic component and the 2 nd electronic component are thermally bonded.

Examples

Experimental examples 1 to 8

(production of anisotropic conductive film)

For 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 conductive characteristics was examined as follows.

First, resin compositions for forming an insulating resin adhesive and an insulating adhesive layer according to the compounding shown in table 1 were prepared. In this case, the minimum melt viscosity of the resin composition is adjusted according to the preparation conditions of the insulating resin composition. The resin composition for forming the insulating resin adhesive was applied onto a PET film having a film thickness of 50. Mu.m, using a bar coater, and dried in an oven at 80℃for 5 minutes, thereby forming an insulating resin adhesive layer having a thickness La shown in Table 2 on the PET film. Similarly, an insulating adhesive layer was formed on the PET film at the thickness shown in table 2.

TABLE 1

Next, a mold was fabricated so that the arrangement of the conductive particles in a plan view was set as shown in table 2 and the distance between the centers of the nearest conductive particles in the repeating units was set to 6 μm. A resin mold having concave portions arranged as shown in table 2 was formed by flowing particles (pellet) of a known transparent resin into the mold in a molten state, and cooling and solidifying the particles. Here, in Experimental example 8, the conductive particles were arranged in a 6-square lattice (number density 32000 pieces/mm) ² ) And one of the lattice axes thereof is inclined by 15 DEG with respect to the longitudinal direction of the anisotropic conductive film.

As the conductive particles, metal-coated resin particles (AUL 703, average particle diameter 3 μm) were prepared, and the conductive particles were filled into the recesses of the resin mold, and the insulating resin binder was coated thereon, and the resin mold was pressed and bonded at 60 ℃ under 0.5 MPa. Then, the insulating resin adhesive was peeled off from the mold, and the conductive particles on the insulating resin adhesive were pressed (pressing condition: 60 to 70 ℃ C., 0.5 MPa.) to press the insulating resin adhesive, thereby producing a film in which the conductive particles in the insulating resin adhesive were buried in the state shown in Table 2. In this case, the embedding state of the conductive particles is controlled by the press-in condition. As a result, in experimental example 4, the film shape was not maintained after the conductive particles were pressed in, but in other experimental examples, a film in which the conductive particles were embedded could be produced. As shown in table 2, the recesses were found around the exposed portions of the embedded conductive particles or directly above the embedded conductive particles by observation with a metal microscope. In addition, in each experimental example except experimental example 4, both the concave portion around the exposed portion of the conductive particle and the concave portion directly above the conductive particle were observed, but the measured values of the concave portions most clearly observed for each experimental example are shown in table 4.

An insulating adhesive layer was laminated on the side of the film in which the conductive particles were embedded, on which the conductive particles were pressed, to produce an anisotropic conductive film having a resin layer of 2 layers. However, in experimental example 4, since the film shape was not maintained after the conductive particles were pressed in, no subsequent evaluation was performed.

(evaluation)

For each of the anisotropic conductive films of the experimental examples, (a) initial on-resistance and (b) on-reliability were measured as follows. The results are shown in Table 2.

(a) Initial on-resistance

The anisotropic conductive films of the respective test examples were sandwiched between a glass substrate on a stage and an IC for evaluating conductive characteristics on a pressing tool side, and heated and pressed (180 ℃ for 5 seconds) by a pressing tool to obtain respective connectors for evaluation. In this case, the pushing force of the pressing tool was varied in 3 stages of low (40 MPa), medium (60 MPa) and high (80 MPa), and 3 kinds of connectors for evaluation were obtained.

Here, the conductive characteristic evaluation IC and the glass substrate have the following dimensions, corresponding to the terminal pattern. In addition, when the evaluation IC and the glass substrate were connected, the long side direction of the anisotropic conductive film and the short side direction of the bump were aligned.

IC for evaluating conduction characteristics

Outline 1.8X20.0 mm

Thickness of 0.5mm

Bump specification size 30×85 μm, bump-to-bump distance 50 μm, bump height 15 μm.

Glass substrate (ITO wiring)

1737F manufactured by CORNING Co., ltd

The outline is 30X 50mm

Thickness of 0.5mm

And an electrode ITO wiring.

The initial on-resistance of the obtained evaluation connector was measured and evaluated according to the following evaluation criteria of 3 stages.

Evaluation criterion of initial on-resistance (in practical use, there is no problem if it is less than 2Ω)

A: less than 0.4 omega

B:0.4Ω or more and less than 0.8Ω

C:0.8Ω or more.

(b) Conduction reliability

The evaluation connector prepared in (a) was placed in a constant temperature bath having a temperature of 85 ℃ and a humidity of 85% rh for 500 hours, and a reliability test was performed, and the on-resistance after that was measured in the same manner as the initial on-resistance, and was evaluated according to the following 3-stage evaluation standard.

Evaluation criterion of conduction reliability (in actual use, there is no problem if it is less than 5Ω)

A: less than 1.2 omega

B:1.2 Ω or more and less than 2 Ω

C:2 Ω or more.

TABLE 2

From table 2, it is clear that it is difficult to form a film having recesses in the insulating resin adhesive in the vicinity of the conductive particles in experimental example 4 in which the minimum melt viscosity of the insulating resin adhesive is 800Pa s. On the other hand, in the experimental example in which the minimum melt viscosity of the insulating resin binder was 1500Pa and s or more, it was found that the protruding portion could 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, and the anisotropic conductive film thus obtained had good conduction characteristics in COG applications. It was also found that in examples 1 to 7 in which the number density of conductive particles was low, anisotropic conductive connection was possible at a lower pressure than in example 8 in which the 6-square lattice arrangement was adopted.

(c) Short circuit rate

Using the anisotropic conductive films of examples 1 to 3 and 5 to 8, the following evaluation ICs of the short circuit ratio were used, the evaluation connectors were obtained under the connection conditions of 180 ℃, 60MPa, and 5 seconds, the number of short circuits of the obtained evaluation connectors was measured, and the ratio of the measured number of short circuits to the number of terminals of the evaluation ICs was calculated as the short circuit ratio.

IC for evaluating short-circuit rate (comb teeth TEG (test element group) having 7.5 μm gaps:

the shape is 15X 13mm

Thickness of 0.5mm

Bump specification size 25×140 μm, bump-to-bump distance 7.5 μm, bump height 15 μm.

If the short circuit is less than 50ppm, it is desirable in practical use, and the anisotropic conductive films of experimental examples 1 to 3 and 5 to 8 are all less than 50ppm.

Further, for each experimental example except experimental example 4, conductive particles captured for each bump were measured, and 10 or more conductive particles were captured.

Experimental examples 9 to 16

(production of anisotropic conductive film)

For the anisotropic conductive film used for the 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 examined as follows.

That is, modulation is absolute according to the coordination shown in Table 3 An anisotropic conductive film was produced in the same manner as in experimental example 1 using the resin composition of the edge resin adhesive and the insulating adhesive layer. The arrangement of the conductive particles and the distance between centers of the nearest conductive particles in this case are shown in table 4. In experimental example 16, the conductive particles were arranged in a 6-square lattice (number density: 15000/mm ² ) And one of the lattice axes thereof is inclined by 15 DEG with respect to the longitudinal direction of the anisotropic conductive film.

In this step of producing an anisotropic conductive film, after the conductive particles were pressed into the insulating resin binder, the film shape was not maintained in experimental example 12, but the film shape was maintained in other experimental examples. Therefore, the anisotropic conductive films of the examples other than the example 12 were observed with a metal microscope to measure the embedded state of the conductive particles, and then the subsequent evaluation was performed. 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 of the recess of the insulating resin adhesive, which is most clearly observed for each experimental example, as in table 2.

(evaluation)

For each of the anisotropic conductive films of the experimental examples, (a) initial on-resistance and (b) on-reliability were measured as follows. The results are shown in Table 4.

(a) Initial on-resistance

The anisotropic conductive films obtained in each experimental example were cut at a thickness of 2mm×40mm, sandwiched between an evaluation FPC for the conductive characteristics and a glass substrate, and heated and pressed (180 ℃ C., 5 seconds) at a tool width of 2mm to obtain each evaluation connection. In this case, 3 kinds of evaluation connectors were obtained by varying the pushing force of the pushing tool in 3 stages of low (3 MPa), medium (4.5 MPa) and high (6 MPa). The on-resistance of the obtained evaluation connector was measured in the same manner as in experimental example 1, and the measured value was evaluated in 3 stages according to the following criteria.

Evaluation FPC:

terminal pitch 20 μm

Terminal width/inter-terminal gap 8.5 μm/11.5 μm

Polyimide film thickness (PI)/copper foil thickness (Cu) =38/8, sn plating.

Alkali-free glass substrate:

electrode ITO wiring

The thickness is 0.7mm.

Evaluation criterion of initial on-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 connector prepared in (a) was placed in a constant temperature bath at 85℃and 85% RH for 500 hours, and the subsequent on-resistance was measured in the same manner as the initial on-resistance, and the measured value was evaluated in 3 stages according to the following criteria.

Evaluation criterion for conduction reliability

A: less than 3.0 omega

B:3.0Ω or more and less than 4Ω

C:4.0Ω or more.

From Table 4, it is clear that it is difficult to form a film having a concave portion in Experimental example 12 in which the minimum melt viscosity of the insulating resin adhesive is 800Pa and s. On the other hand, in the experimental example in which the minimum melt viscosity of the insulating resin layer was 1500Pa and s or more, it was found that by adjusting the conditions at the time of embedding the conductive particles, the concave portions could be formed in the vicinity of the conductive particles of the insulating resin binder, and the anisotropic conductive film thus obtained had good conduction characteristics in the FOG application.

(c) Short circuit rate

The number of short circuits of the evaluation connector, the initial on-resistance of which was measured, and the occurrence rate of short circuits was determined from the measured number of short circuits and the number of gaps of the evaluation connector. If the short circuit occurrence rate is less than 100ppm, there is no problem in practical use.

The incidence of short-circuiting was less than 100ppm in any of examples 9 to 11 and 13 to 16.

Further, for each experimental example except experimental example 12, conductive particles captured for each bump were measured, and 10 or more conductive particles were captured.

TABLE 3

TABLE 4

Description of the reference numerals

1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1A, 1B, 1C, 1D, 1E; 2. 2a, 2b, 2c, 2s conductive particles; 2m, 2n, 2o, 2p, 2q, 2r of columns of conductive particles; 2t top of conductive particles; 3. an insulating resin binder; 3a surface of an insulating resin adhesive; 3b, 3c recesses; a 3P tangent plane; 4. an insulating adhesive layer; 5. 5B repeat units; 5a is parallel to the long side direction of the anisotropic conductive film; 5b sides parallel to the short side direction of the anisotropic conductive film; 5x are sequentially connected with the centers of the conductive particles forming the outline of the repeating unit to form a polygon; d average particle diameter; l1, L2 circumscribes; thickness of La insulating resin binder; the embedding amount of Lb conductive particles; diameter of exposed portion of Lc conductive particles; maximum diameter of Ld recess; le, lf maximum depth.

Claims

1. An anisotropic conductive film comprising conductive particles disposed on an insulating resin adhesive,

the repeating units of the conductive particles are repeatedly arranged, the repeating units of the conductive particles are formed by combining conductive particle rows in which conductive particles of different numbers are arranged in parallel and are arranged in a row at intervals, centers of the conductive particles constituting the outline of the repeating units are sequentially connected to form a polygon, and a region where the conductive particles are not arranged is present between the repeating units which are repeatedly arranged.

2. The anisotropic conductive film according to claim 1, wherein the repeating unit is disposed over the entire surface of the anisotropic conductive film.

3. The anisotropic conductive film according to claim 1, wherein the conductive particles constituting the repeating unit are arranged such that predetermined lattice points are regularly omitted from the arrangement of lattice points where the conductive particles exist in 6 lattices or square lattices.

4. The anisotropic conductive film of claim 1, wherein the number of conductive particles constituting the parallel conductive particle array in the repeating unit is gradually different.

5. The anisotropic conductive film according to claim 1, wherein among the 3 parallel conductive particle rows in the repeating unit, the number of conductive particles constituting the central conductive particle row is greater or less than the number of conductive particles constituting the conductive particle rows on both sides.

6. The anisotropic conductive film according to claim 1, wherein each side of the polygon constituting the repeating unit is diagonal to the long side direction or the short side direction of the anisotropic conductive film.

7. The anisotropic conductive film according to claim 1, wherein the polygon constituting the repeating unit has sides parallel to a long side direction or a short side direction of the anisotropic conductive film.

8. The anisotropic conductive film of claim 1, wherein the columns of conductive particles are parallel to each other in the repeating unit.

9. The anisotropic conductive film of claim 1, wherein individual conductive particles are repeatedly arranged together with the repeating unit.

10. The anisotropic conductive film according to claim 1, wherein the nearest distance between adjacent conductive particles in the repeating unit is 0.5 times or more the average particle diameter of the conductive particles.

11. The anisotropic conductive film according to claim 1 or 2, wherein an insulating adhesive layer having a viscosity or adhesiveness different from that of a resin constituting the insulating resin adhesive is laminated on the insulating resin adhesive provided with the conductive particles.

12. A connection structure for anisotropically electrically connecting the 1 st electronic component and the 2 nd electronic component by the anisotropic conductive film according to any one of claims 1 to 11.

13. A method for producing a connection structure by pressure bonding a 1 st electronic component and a 2 nd electronic component via an anisotropic conductive film, wherein the anisotropic conductive film according to any one of claims 1 to 11 is used as the anisotropic conductive film.

14. An anisotropic conductive film comprising conductive particles disposed on an insulating resin adhesive,

comprises polygonal repeating units formed by combining conductive particle rows arranged in a row with conductive particles at intervals, wherein regions where no conductive particles are arranged exist between the polygonal repeating units,

the polygon of the repeating unit is inclined with the long side direction or the short side direction of the anisotropic conductive film.

15. The anisotropic conductive film of claim 14, wherein the repeating units are disposed throughout the entire face of the anisotropic conductive film.

16. The anisotropic conductive film according to claim 14 or 15, wherein the conductive particles constituting the repeating unit are arranged such that predetermined lattice points are regularly omitted from the arrangement of lattice points where the conductive particles exist in 6 lattices or square lattices.

17. The anisotropic conductive film of claim 14, wherein the repeating units having different numbers of conductive particles are arranged with a pitch therebetween in the parallel conductive particle rows.

18. The anisotropic conductive film of any of claims 14, 15, 17, wherein the number of conductive particles constituting the parallel conductive particle rows in the repeating unit is gradually different.

19. The anisotropic conductive film according to any of claims 14, 15, and 17, wherein the number of conductive particles constituting the central conductive particle row is greater or less than the number of conductive particles constituting the both conductive particle rows among the 3 conductive particle rows juxtaposed in the repeating unit.

20. The anisotropic conductive film according to any of claims 14, 15, 17, wherein each side of the polygon constituting the repeating unit is diagonal to the long side direction or the short side direction of the anisotropic conductive film.

21. The anisotropic conductive film according to any of claims 14, 15, 17, wherein the polygon constituting the repeating unit has sides parallel to the long side direction or the short side direction of the anisotropic conductive film.

22. The anisotropic conductive film of any of claims 14, 15, 17, wherein the columns of conductive particles are parallel to each other in the repeating unit.

23. The anisotropic conductive film of any of claims 14, 15, 17, wherein individual conductive particles are repeatedly arranged together with the repeating unit.

24. The anisotropic conductive film according to any of claims 14, 15, and 17, wherein the nearest distance between adjacent conductive particles in the repeating unit is 0.5 times or more the average particle diameter of the conductive particles.

25. The anisotropic conductive film according to any of claims 14, 15, and 17, wherein an insulating adhesive layer having a viscosity or adhesiveness different from that of a resin constituting the insulating resin adhesive is laminated on the insulating resin adhesive provided with the conductive particles.

26. A connection structure for anisotropically electrically connecting the 1 st electronic component and the 2 nd electronic component by the anisotropic conductive film according to any one of claims 14 to 25.

27. A method for producing a connection structure by pressure bonding a 1 st electronic component and a 2 nd electronic component via an anisotropic conductive film, wherein the anisotropic conductive film according to any one of claims 14 to 25 is used as the anisotropic conductive film.

28. An anisotropic conductive film comprising conductive particles disposed on an insulating resin adhesive,

the repeating units of the conductive particles are repeatedly arranged, the repeating units of the conductive particles are formed by combining conductive particle rows of which the conductive particles with different numbers are arranged in parallel and are arranged in a row at intervals,

There are areas between the repeatedly arranged repeating units where the conductive particles are not arranged.

29. The anisotropic conductive film of claim 28, wherein the repeating units are disposed throughout the entire face of the anisotropic conductive film.

30. The anisotropic conductive film according to claim 28 or 29, wherein the conductive particles constituting the repeating unit are arranged such that predetermined lattice points are regularly omitted from the arrangement of lattice points where the conductive particles exist in 6 lattices or square lattices.

31. The anisotropic conductive film of claim 28 or 29, wherein the number of conductive particles constituting the parallel conductive particle array in the repeating unit is gradually different.

32. The anisotropic conductive film of claim 28 or 29, wherein among the 3 parallel conductive particle rows in the repeating unit, the number of conductive particles constituting the central conductive particle row is greater or less than the number of conductive particles constituting the conductive particle rows on both sides.

33. The anisotropic conductive film according to claim 28 or 29, wherein each side of the polygon formed by sequentially connecting the centers of the conductive particles constituting the outer shape of the repeating unit is diagonal to the long side direction or the short side direction of the anisotropic conductive film.

34. The anisotropic conductive film according to claim 28 or 29, wherein the polygon formed by sequentially connecting the centers of the conductive particles constituting the outer shape of the repeating unit has sides parallel to the long side direction or the short side direction of the anisotropic conductive film.

35. The anisotropic conductive film of claim 28 or 29, wherein the columns of conductive particles are parallel to each other in the repeating unit.

36. The anisotropic conductive film of claim 28 or 29, wherein individual conductive particles are repeatedly arranged together with the repeating unit.

37. The anisotropic conductive film of claim 28 or 29, wherein the nearest distance between adjacent conductive particles in the repeating unit is 0.5 times or more the average particle diameter of the conductive particles.

38. A connection structure for anisotropically electrically connecting the 1 st electronic component and the 2 nd electronic component by the anisotropic conductive film according to any one of claims 28 to 37.

39. A method for producing a connection structure by thermocompression bonding a 1 st electronic component and a 2 nd electronic component via an anisotropic conductive film, wherein the anisotropic conductive film according to any one of claims 28 to 37 is used as the anisotropic conductive film.