TW201807131A - Anisotropic conductive film - Google Patents

Abstract

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. 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.

Description

Anisotropic conductive film

The present invention relates to an anisotropic conductive film.

An anisotropic conductive film obtained by dispersing conductive particles in an insulating resin adhesive is widely used when mounting electronic components such as IC chips on wiring boards. In the anisotropic conductive film, it is strongly required that the narrowing of the bumps accompanied by the high-density mounting of electronic parts to improve the capture of conductive particles in the bumps and avoid short-circuits between adjacent bumps.

In response to such a requirement, it has been proposed to arrange the arrangement of the conductive particles in the anisotropic conductive film into a lattice-like arrangement, and to tilt the axis of the array relative to the long-side direction of the anisotropic conductive film (Patent Document 1, Patent Reference 2).

Patent Document 1: Japanese Patent No. 4887700

Patent Document 2: Japanese Unexamined Patent Publication No. 9-320345

As described in Patent Documents 1 and 2, the conductive particles are arranged in a simple lattice shape. In this case, the layout of the bumps should be dealt with by the inclination angle of the alignment axis or the distance between the conductive particles. Therefore, if the bumps have a narrow pitch, the distance between the conductive particles must be reduced, and the number density of the conductive particles increases, resulting in an increase in the manufacturing cost of the anisotropic conductive film.

In addition, in order to reduce the distance between the conductive particles and avoid short circuits, it is necessary to suppress the conductive particles from flowing away due to the resin flow of the insulating resin adhesive during anisotropic conductive connection. The design of the insulating resin adhesive also has Constraints.

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

The present inventors have found that instead of setting the conductive particles in a planar view of the anisotropic conductive film in a simple lattice-like arrangement, the conductive members are repeatedly arranged in the vertical and horizontal directions by repeating a polygonal unit composed of a plurality of conductive particles. Particles, and the sides forming the polygon are diagonally intersected with respect to the long-side direction or the short-side direction of the anisotropic conductive film, so that the above-mentioned problem can be solved, and the present invention is considered.

That is, the present invention provides an anisotropic conductive film, in which conductive particles are arranged in an insulating resin adhesive, and a polygonal repeating unit is repeatedly arranged in a plan view. The polygonal repeating unit is a plurality of conductive particles. The centers are sequentially connected and formed, and the polygon of the repeating unit has sides that obliquely intersect with the long side direction or the short side direction of the anisotropic conductive film.

According to the anisotropic conductive film of the present invention, each conductive particle is not made simple. The lattice-like arrangement is a repeating arrangement of repeating units formed by a plurality of conductive particles, so that the shortened part of the distance between conductive particles exists uniformly in the entire film. In addition, since the polygon of the repeating unit has an edge obliquely intersecting with the long-side direction or the short-side direction of the anisotropic conductive film, the catchability of the conductive particles in the bump is high. Therefore, it is possible to connect narrow pitch bumps without causing a short circuit.

On the other hand, according to the anisotropic conductive film of the present invention, since the portion where the inter-particle distance of the conductive particles is enlarged also exists uniformly in the entire film, the number density of the conductive particles in the entire anisotropic conductive film can be suppressed. The increase suppresses an increase in manufacturing cost as the number density of conductive particles increases. In addition, by suppressing an increase in the number density of conductive particles, it is also possible to suppress an increase in the thrust required to press the jig during anisotropic conductive connection. Therefore, the pressure exerted on the electronic component by the self-pressing jig during anisotropic conductive connection can be reduced, and the deformation of the electronic component can be prevented.

1A, 1Ba, 1Bb, 1Ca, 1Cb, 1Da, 1Db, 1Ea, 1Eb, 1F, 1G, 1H, 1I, 1J, 1K, 1L, 1M, 1a, 1b, 1c, 1d, 1e‧‧‧Anisotropic conductive membrane

2, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2p, 2q, 2r, 2s, 2t, 2u‧‧‧ conductive particles

3‧‧‧Insulating resin adhesive

4‧‧‧ Insulating Adhesive Layer

5, 5B‧‧‧‧ Repeat unit

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 the conductive particles of 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 of the anisotropic conductive film 1Ba in the example.

FIG. 2B is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1Bb of the embodiment.

FIG. 3A is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1Ca in the example.

FIG. 3B is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1Cb of the embodiment.

FIG. 4A is a plan view illustrating the arrangement of the conductive particles of the anisotropic conductive film 1Da in the example.

FIG. 4B is a plan view illustrating the arrangement of the conductive particles of the anisotropic conductive film 1Db of the embodiment.

FIG. 5A is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1Ea of the embodiment.

FIG. 5B is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1Eb of the embodiment.

FIG. 6 is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1F of the embodiment.

FIG. 7 is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1G in the example.

FIG. 8 is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1H in the example.

FIG. 9 is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1I of the embodiment.

FIG. 10 is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1J in the example.

FIG. 11 is a plan view illustrating the arrangement of the conductive particles of the anisotropic conductive film 1K in the example.

FIG. 12 is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1L of the embodiment.

FIG. 13 is a plan view illustrating the arrangement of conductive particles of the anisotropic conductive film 1M in the example.

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 addition, in each figure, the same symbol represents the same or equivalent component.

<Overall Structure of Anisotropic Conductive Film>

FIG. 1A is a plan view showing the arrangement of conductive particles of an anisotropic conductive film 1A according to an embodiment of the present invention, and FIG. 1C is a cross-sectional view thereof.

This anisotropic conductive film 1A has a structure in which conductive particles 2 are arranged in a single layer on or near the surface of an insulating resin adhesive 3, and an insulating adhesive layer 4 is laminated thereon.

In addition, as the anisotropic conductive film of the present invention, a configuration in which the insulating adhesive layer 4 is omitted and the conductive particles 2 are embedded in the insulating resin adhesive 3 may be adopted.

<Conductive particles>

As the conductive particle 2, a user in a known anisotropic conductive film can be appropriately selected and used. Examples include: metal particles such as nickel, copper, silver, gold, and palladium; polyamine and polyphenylguanidine coated with a metal such as nickel (polybenzoguanamine) and other metal particles coated with resin particles. 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 still more preferably 2 μm or more and 6 μm or less.

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 viewed from the top, and the particle diameter may be measured and determined. In this case, it is preferable to measure 200 or more, more preferably 500 or more, and even more preferably 1,000 or more.

The surface of the conductive particles 2 is preferably covered by an insulating coating or an insulating particle treatment. Such a coating is easily peeled from the surface of the conductive particles 2 and does not hinder anisotropic conductive connection. Furthermore, protrusions may be provided on the entire surface or a part of the conductive particles 2. The height of the protrusion is within 20% of the conductive particle diameter, and preferably within 10%.

<Arrangement of conductive particles>

In FIGS. 1A to 7 below, as an example, an example of the arrangement of the repeating units when the polygonal repeating unit 5 is trapezoidal will be described.

The arrangement of the conductive particles 2 in a plan view of the anisotropic conductive film 1A shown in FIG. 1A is as follows: a polygonal repeating unit 5 formed by sequentially connecting the centers of a plurality of conductive particles 2a, 2b, 2c, and 2d is along a positive direction. The two intersecting directions (X direction, Y direction) overlap and are arranged on one surface (that is, the entire surface) of the anisotropic conductive film 1. In addition, the anisotropic conductive film of the present invention may have a region where no conductive particles are arranged, if necessary.

The arrangement of the conductive particles 2 can also be regarded as the arrangement of the conductive particles in 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). In other words, it can be considered that the conductive particles have a configuration in which the conductive particles of a specific lattice point are regularly removed from the arrangement of the conductive particles in each lattice point of the hexagonal lattice. Therefore, the vertex of the trapezoid of the repeating unit 5 composed of the conductive particles 2a, 2b, 2c, and 2d becomes a part of a regular hexagon combined with a regular triangle, and exists at the lattice point of the hexagonal lattice. If one of the trapezoidal edges 2a, 2b is used as the center to invert, the edges 2c, 2d and the adjacent repeating unit of the trapezoid (that is, the repeating unit composed of the conductive particles 2e, 2f, 2g, 2h), 2h overlap.

Moreover, when considering the repeating unit of the conductive particle 2, it can also be regarded as a regular hexagonal repeating unit 5x along the X composed of the conductive particles 2p, 2q, 2r, 2s, 2t, and 2u as shown in FIG. 1B. The direction overlaps one side and repeats, and repeats without overlapping the edges and vertices along the Y direction. In the present invention, the repeating unit is preferably regarded as a polygon composed of 4 or more conductive particles, and it is In the case of an angular edge, a polygon having the smallest unit repeating in the vertical and horizontal directions of the anisotropic conductive film.

Each side of the trapezoid of the repeating unit 5 (FIG. 1A) obliquely intersects the long side direction and the short side direction of the anisotropic conductive film 1A. Thereby, the outer tangent line L1 of the longitudinal direction of the anisotropic conductive film of the conductive particle 2a penetrates the conductive particle 2b, and the conductive particle 2b is adjacent to the conductive particle 2a in the longitudinal direction of the anisotropic conductive film. In addition, the outer tangent line L2 of the short-side direction of the anisotropic conductive film of the conductive particles 2a penetrates the conductive particles 2d, and the conductive particles 2d are adjacent to the conductive particles 2a in the short-side direction of the anisotropic conductive film. Since the long-side direction of the anisotropic conductive film becomes the short-side direction of the bump during anisotropic conductive connection, if the polygonal side of the repeating unit 5 and the anisotropic conductive film 1A The oblique crossing of the long side direction or the short side direction can prevent the plurality of conductive particles from being arranged in a straight line along the edge of the bump, thereby preventing the plurality of conductive particles arranged in a line from leaving the terminal together and becoming helpless. Because of the phenomenon of conduction, the capturing property of the conductive particles 2 can be improved.

Furthermore, in the present invention, the repeating unit may not necessarily have all sides obliquely intersecting with the long side direction or the short side direction of the anisotropic conductive film, and the short side direction of each bump becomes the long side direction of the anisotropic conductive film. In this case, it is preferable that each side of the repeating unit and the long-side direction or short-side direction of the anisotropic conductive film intersect with each other in terms of the capturing property of the conductive particles.

In contrast, when the arrangement pattern of the bumps is radial (so-called fan-out bumps), it is preferable to form the polygon of the repeating unit with the sides of the long-side direction or the short-side direction of the anisotropic conductive film. That is, in order to realize that the bumps to be connected are not displaced even if they are thermally expanded, the arrangement pattern of the bumps may be made radial (for example, Japanese Patent Laid-Open No. 2007-19550, Japanese Patent Laid-Open No. 2015-232660, etc.) ), In this case, the angle formed by the long side direction of each bump and the long side direction and short side direction of the anisotropic conductive film gradually changes. Therefore, even if the polygonal sides of the repeating unit 5 are not diagonally intersected with the long-side direction or the short-side direction of the anisotropic conductive film, the polygonal sides of the repeating unit 5 and the lengths of the bumps arranged radially are not crossed. The edges in the side direction are skewed. Therefore, it is possible to avoid the phenomenon that most conductive particles attached to the edges of the bumps are not captured by the bumps during the anisotropic conductive connection, resulting in a reduction in the catchability of the conductive particles.

On the other hand, the radial arrangement pattern of the bumps is usually formed symmetrically. Therefore, in terms of the ease of confirming the connection state by the indentation after the anisotropic conductive connection, it is preferable to form the long side direction or the short side direction of the polygonal anisotropic conductive film of the repeating unit 5 The sides of the anisotropic conductive film, in particular, the sides of the polygon with the anisotropic conductive film forming the repeating unit 5 are the axes of symmetry of the short side or the long side of the anisotropic conductive film. The repeating unit 5 is repeatedly arranged along the long side direction or the short side direction of the anisotropic conductive film. For example, as shown in the anisotropic conductive film 1Ba shown in FIG. 2A, the trapezoid of the repeating unit 5 can be set as a trapezoid having an axis of symmetry in the short-side direction of the anisotropic conductive film, so that the bottom edge and the top edge thereof are different from the anisotropy. The long sides of the conductive film are parallel. Alternatively, as shown in the anisotropic conductive film 1Bb shown in FIG. 2B, the bottom and top sides of the same trapezoidal repeating unit are parallel to the short side of the anisotropic conductive film. .

In the present invention, the arrangement of the conductive particles 2 in the repeating unit 5 or the vertical and horizontal repeating pitches of the repeating unit 5 can be appropriately changed according to the shape or pitch of the terminals as the connection target of the anisotropic conductive connection. Therefore, as compared with the case where the conductive particles 2 are arranged in a simple lattice shape, the entire anisotropic conductive film can achieve a higher capturing property with a smaller number of conductive particles. For example, for the anisotropic conductive film 1Ba, in order to increase the number density of conductive particles in the longitudinal direction of the anisotropic conductive film, the following configuration can also be set: as shown in FIG. 3A, the anisotropic conductive film 1Ca , Repeating the trapezoidal repeating unit 5 along the width direction of the anisotropic conductive film with its shape, and repeating the trapezoidal repeating unit 5 and repeating unit 5B alternately along the long side of the anisotropic conductive film, the repeating unit 5B is a shape obtained by inverting the repeating unit of the trapezoid along the axis of the long side of the film. In this case, it can also be set as follows: like the anisotropic conductive film 1Da shown in FIG. 4A, the trapezoidal repeating unit 5 is also repeated alternately along the short side direction of the anisotropic conductive film and reversed. Shaped repeating unit 5B.

Similarly, for the anisotropic conductive film 1Bb, in order to increase the number density of conductive particles in the short-side direction of the anisotropic conductive film, the following configuration can also be set: the anisotropic conductive film 1Cb shown in FIG. 3B Generally, the repeating unit 5 in the trapezoid shape is repeated along the longitudinal direction of the anisotropic conductive film, and the repeating unit 5 and the repeating unit 5 are repeated in the width direction of the anisotropic conductive film. Element 5B is repeated alternately, and the repeating unit 5B is a shape obtained by inverting the repeating unit along the axis of the short side direction of the anisotropic conductive film. In addition, it may be set as follows: as shown in the anisotropic conductive film 1Db shown in FIG. 4B, the repeating unit 5 is reversed along the long side direction and the short side direction of the anisotropic conductive film. The repeating unit 5B of the shape is repeated alternately.

Furthermore, for the anisotropic conductive film 1Ca, in order to reduce the number density in the short-side direction of the anisotropic conductive film, as shown in the anisotropic conductive film 1Ea shown in FIG. 5A, the difference between the repeating units 5, 5B can be enlarged In order to reduce the number density of the anisotropic conductive film in the longitudinal direction, the repeating columns of the anisotropic conductive film are spaced from each other. The repeating unit 5 can be enlarged as shown in the anisotropic conductive film 1Eb shown in FIG. 5B. 5B, the repeated rows in the width direction of the anisotropic conductive film are spaced from each other.

In addition, as in the anisotropic conductive film 1F shown in FIG. 6, the arrangement of the conductive particles in the anisotropic conductive film 1A shown in FIG. 1A may be performed to increase the repeating pitch in the Y direction of the repeating unit 5. In the configuration of the conductive particles 2 shown in FIG. 1A, each of the conductive particles 2 overlaps with any of the vertices of the regular hexagon when the regular hexagons are arranged without a gap, but in the configuration of the conductive particles shown in FIG. It is not necessary that all the conductive particles become the vertexes of the regular hexagon when the regular hexagons are arranged without a gap, which is different from the configuration of the conductive particles shown in FIG. 1A in this respect.

In addition, as shown in the anisotropic conductive film 1G shown in FIG. 7, the repeating distance in the Y direction can be further enlarged, and separate conductive particles 2p can be arranged between the repeating units 5 adjacent to each other in the Y direction. unit. In addition, the repeating pitch in the X direction of the repeating unit 5 may be appropriately changed, and separate conductive particles or other repeating units may be arranged between the repeating pitches in the X direction.

As shown in the anisotropic conductive film 1H shown in FIG. 8, the repeating unit 5 in the trapezoidal shape may be repeated in the short-side direction or the long-side direction of the anisotropic conductive film. 5B, and a separate row of conductive particles 2p is arranged between a column in the width direction of the anisotropic conductive film of the repeating unit 5 and a column in the width direction of the anisotropic conductive film of the repeating unit 5B. Thereby, the arrangement in which the conductive particles 2 are arranged in an orthorhombic lattice, and individual conductive particles 2p exist in the center of the unit lattice. When the conductive particles are arranged in an orthorhombic lattice, in order to reduce the number density of the conductive particles, the repeating unit 5 itself may be formed into a rhombus like the anisotropic conductive film 1I shown in FIG. 9. By disposing the conductive particles 2 in an orthorhombic lattice shape as shown in FIGS. 8 and 9, the conductive particles 2 exist in the long-side direction, the short-side direction, and the directions inclined with respect to the anisotropic conductive film. Therefore, it becomes easy to balance the improvement of the capture property of the conductive particles and the suppression of the short circuit during the anisotropic conductive connection.

Alternatively, the arrangement may be such that, as shown in the anisotropic conductive film 1J shown in FIG. 10, a rectangular lattice-shaped repeating unit 5 of rhombic repeating units 5 composed of four conductive particles is arranged, and the repeating unit 5 is arranged. The rectangular lattice-like arrangement of the rhombic repeating units 5B reversed in the long-side direction or the short-side direction of the anisotropic conductive film is repeated so that the lattice points do not overlap. Alternatively, as shown in the anisotropic conductive film 1K shown in FIG. 11, the particles may be arranged in the same particles as the anisotropic conductive film 1J shown in FIG.

The repeating unit is not limited to the arrangement of a part of the apex of the regular hexagon (that is, the lattice point of the hexagonal lattice) when the conductive particles occupy a regular triangle arranged without gaps. It is also possible that the conductive particles occupy a part of the lattice points of the square lattice. For example, the repeating unit 5 of the trapezoidal repeating unit 5B may be alternately repeated along the long side and the short side direction of the anisotropic conductive film in the same arrangement as the conductive particles shown in FIG. 5A. An anisotropic conductive film 1L arranged as shown in FIG. 12 is formed on a lattice point of a square lattice.

In addition, the number of vertices forming a polygon of a repeating unit is not limited to four, but may be 5 or more, 6 or more, or 7 or more. However, in the design or production steps of anisotropic conductive film manufacturing, in order to easily identify the shape of the repeating unit, it is preferable to set the number of vertices of the repeating unit to an even number.

The shape of the polygon forming the repeating unit may or may not be a regular polygon. In terms of easy identification of the shape of the repeating unit, a shape having an axis of symmetry is preferred. In this case, each conductive particle constituting the repeating unit may not exist in the lattice point of the hexagonal lattice or the square lattice. 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 apex of a regular octagon. The shape of the polygon of the repeating unit can be based on the shape and pitch of the bumps or terminals for the anisotropic conductive connection, the inclination angles of the long sides of the bumps or terminals with respect to the long side direction of the film of the anisotropic conductive film, The resin composition of the insulating resin adhesive in the oriented conductive film is appropriately determined.

In addition, the arrangement of the conductive particles in the present invention is not limited to the arrangement of the repeating units shown in the figure, for example, the arrangement of the repeating units shown in the figure may be inclined. In this case, a state in which the long-side direction and the short-side direction of the exchange membrane are formed by inclining 90 ° is also included. The interval between the repeating units or the interval between conductive particles in the repeating unit may be changed.

<The shortest distance between conductive particles>

The shortest inter-particle distance between conductive particles is preferably between 0.5 times or more the average particle diameter of the conductive particles, between adjacent conductive particles within the repeating unit and between adjacent conductive particles between the repeating units. If the distance is too short, it becomes easy to cause a short circuit due to the contact between the conductive particles. The upper limit of the distance between adjacent conductive particles is determined according to the bump shape or the bump pitch. For example, when the bump width is 200 μm and the inter-bump space is 200 μm, the conductive particles are placed between the bump width or between the bumps. When there is at least one of any of the spaces, the shortest inter-particle distance of the conductive particles is set to less than 400 μm. It is preferable that the capture property of a conductive particle is less than 200 micrometers.

<Number density of conductive particles>

The number density of the conductive particles is in terms of suppressing the manufacturing cost of the anisotropic conductive film and avoiding the excessive thrust required by the pressing jig used in the anisotropic conductive connection. In the case of 10 μm, it is preferably 50,000 pieces / mm ² or less, more preferably 35,000 pieces / mm ² or less, and even more preferably 30,000 pieces / mm ² or less. On the other hand, if the number density of the conductive particles is too small, there may be a risk of poor conduction due to the terminal not sufficiently capturing the conductive particles, so it is preferably 300 pieces / mm ² or more, more preferably 500 pieces / mm ² or more, It is preferably 800 pieces / mm ² or more.

Furthermore, if the average particle diameter of the conductive particle of less than 10μm situation, preferably 15 / mm ² or more, more preferably 50 / mm ² or more, and further preferably 160 / mm ² or more. The reason for this is that as the conductive particle size becomes larger, the occupied area ratio of the conductive particles also increases. For the same reason, it is preferably 1800 pieces / mm ² or less, more preferably 1100 pieces / mm ² or less, and still more preferably 800 pieces / mm ² or less.

In addition, the number density of the conductive particles may deviate locally (for example, 200 μm × 200 μm) from the number density.

<Insulating resin adhesive>

As the insulating resin adhesive 3, a thermally polymerizable composition, a photopolymerizable composition, and a photopolymerizable polymerizable composition used as an insulating resin adhesive in a known anisotropic conductive film can be appropriately selected and used. Among them, examples of the thermally polymerizable composition include a thermal radically polymerizable resin composition containing an acrylate compound and a thermal radical polymerization initiator, and an epoxy compound and heat. Thermal photocationically polymerizable resin compositions of cationic polymerization initiators, thermal anion polymerizable resin compositions containing epoxy compounds and thermal anionic polymerization initiators, and the like. Examples of the photopolymerizable composition include an acrylate compound and light. Photo-radical polymerizable resin composition of a radical polymerization initiator and the like. A plurality of polymerizable compositions may be used in combination as long as no particular problem occurs. Examples of the combined use include a combination of a thermal cationic polymerizable composition and a thermal radical polymerizable composition.

Here, the photopolymerization initiator may contain a plurality of initiators that react with light having different wavelengths. This makes it possible to distinguish the wavelengths used in the light curing of the resin constituting the insulating resin layer during the manufacture of the anisotropic conductive film and the light curing of the resin used to bond electronic parts to each other during the anisotropic conductive connection.

When the photopolymerizable composition is used to form the insulating resin adhesive 3, all or a part of the photopolymerizable compound contained in the insulating resin adhesive 3 can be cured by light curing during the production of the anisotropic conductive film. Part of the light is hardened. By this photo-hardening, the arrangement of the conductive particles 2 in the insulating resin adhesive 3 can be maintained or fixed, and the suppression of short-circuiting and the improvement of trapping can be expected. In addition, by adjusting the conditions of the photohardening, the viscosity of the insulating resin layer in the manufacturing step of the anisotropic conductive film can be adjusted.

The blending amount of the photopolymerizable compound in the insulating resin adhesive 3 is preferably 30% by mass or less, more preferably 10% by mass or less, and further preferably less than 2% by mass. The reason for this is that, if there are too many photopolymerizable compounds, the thrust force applied by press-fitting during anisotropic conductive connection increases.

On the other hand, a thermally polymerizable composition contains a thermally polymerizable compound and a thermal polymerization initiator, and as this thermally polymerizable compound, those who also function as a photopolymerizable compound can be used. In addition, the thermally polymerizable composition may contain photopolymerization in addition to the thermally polymerizable compound. And a photopolymerizable initiator. It is preferable to contain a photopolymerizable compound and a photopolymerization initiator in addition to 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 thermally polymerizable compound, a photo radical initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. . The hardened | cured material of these polymerizable compositions may be contained in the insulating adhesive agent 3.

As the acrylate compound used as a thermal or photopolymerizable compound, a conventionally known thermally polymerizable (meth) acrylate monomer can be used. For example, a monofunctional (meth) acrylate-based monomer or a difunctional or more multifunctional (meth) acrylate-based monomer can be used.

In addition, if the epoxy compound used as the polymerizable compound forms a three-dimensional network structure and provides good heat resistance and adhesion, it is preferred to use a solid epoxy resin and a liquid epoxy resin together. Here, a solid epoxy resin means the epoxy resin which is solid at normal temperature. The liquid epoxy resin means an epoxy resin that is liquid at normal temperature. The normal temperature means a temperature range of 5 to 35 ° C. specified by JIS Z 8703. In the present invention, two or more epoxy compounds may be used in combination. In addition to the epoxy compound, an oxetane compound may be used in combination.

The solid epoxy resin is not particularly limited as long as it is compatible with the liquid epoxy resin and is solid at normal temperature. Examples thereof include bisphenol A epoxy resin, bisphenol F epoxy resin, and polyfunctional epoxy resin. Resin, dicyclopentadiene-type epoxy resin, novolac phenol-type epoxy resin, biphenyl-type epoxy resin, naphthalene-type epoxy resin, etc., may be used singly or in combination of two or more kinds While using. Among these, a bisphenol A type epoxy resin is 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 epoxy resin, bisphenol F epoxy resin, novolac phenol epoxy resin, and naphthalene epoxy resin. A resin, etc. may be used individually by 1 type, or may be used in combination of 2 or more type. In particular, from the viewpoints of film viscosity 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 which does not generate nitrogen gas that causes bubbles can be preferably used.

If the amount of the thermal radical polymerization initiator is too small, it will cause poor curing, and if it is too large, the product life will be reduced. Therefore, it is preferably 2 to 60 with respect to 100 parts by mass of the (meth) acrylate compound. Part by mass, more preferably 5 to 40 parts by mass.

As the thermal cationic polymerization initiator, a known thermal cationic polymerization initiator for an epoxy compound can be used. For example, sulfonium salts, sulfonium salts, sulfonium salts, ferrocene, etc., which generate an acid by heat, can be used. In particular, an aromatic sulfonium salt that exhibits good latentness to temperature can be preferably used.

If the amount of the thermal cationic polymerization initiator is too small, it will tend to become poor in hardening, and if it is too much, it will tend to reduce the product life. Therefore, it is preferably 2 to 60 parts by mass relative to 100 parts by mass of the epoxy compound, more preferably 5 to 40 parts by mass.

As the thermal anionic polymerization initiator, a commonly known one can be used. Examples include organic acids such as dihydrazine, dicyandiamine, amine compounds, polyamidoamine compounds, cyanate ester compounds, phenol resins, acid anhydrides, carboxylic acids, tertiary amine compounds, imidazoles, Lewis acids, Bronister An acid salt, a polythiol-based hardener, a urea resin, a melamine resin, an isocyanate compound, a blocked isocyanate compound, and the like may be used singly or in combination of two or more kinds. Among these, a microcapsule-type latent hardener formed by using an imidazole modifier as a core and coating its surface with a polyurethane is preferably used.

It is preferred to include a film-forming resin in the thermally polymerizable composition. The film-forming resin corresponds to, for example, a high-molecular-weight resin having an average molecular weight of 10,000 or more. From the viewpoint of film-forming properties, The average molecular weight is preferably about 10,000 to 80,000. Examples of the film-forming resin include phenoxy resins, polyester resins, polyurethane resins, polyester amine resins, acrylic resins, polyimide resins, and butyraldehyde resins. These can be used alone or in combination. Use in combination of 2 or more types. Among these, a phenoxy resin is preferably used suitably from a viewpoint of a film formation state, connection reliability, and the like.

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

Furthermore, it may contain fillers, softeners, accelerators, anti-aging agents, colorants (pigments, dyes), organic solvents, ion catcher agents, and the like, which are different from the above-mentioned insulating fillers.

Further, if necessary, a stress relaxation agent, a silane coupling agent, an inorganic filler, and the like may be blended. Examples of the stress relaxation agent include a hydrogenated styrene-butadiene block copolymer, a hydrogenated styrene-isoprene block copolymer, and the like. In addition, examples of the silane coupling agent include epoxy-based, methacryl-fluorenyl-based, amine-based, vinyl-based, mercapto / thioether-based, and urea-based. Examples of the inorganic filler include silicon dioxide, talc, titanium oxide, calcium carbonate, and magnesium oxide.

The insulating resin adhesive 3 can be formed by forming and drying a coating composition containing the resin by a coating method, or further curing the coating composition, or by forming a film by a known method in advance. The insulating resin adhesive 3 can also be obtained by laminating a resin layer 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 adhesive 3 can be appropriately determined according to a method of manufacturing the anisotropic conductive film and the like. For example, when a method for manufacturing an anisotropic conductive film is used to hold conductive particles on the surface of an insulating resin adhesive in a specific arrangement, and press the conductive particles into the insulating resin adhesive, In terms of making the insulating resin adhesive film-forming, it is preferable to set the minimum melt viscosity of the resin to 1100 Pa · s or more. Further, as described below, as shown in FIG. 14 or FIG. 15, a recessed portion 3 b is formed around the exposed portion of the conductive particles 2 pressed into the insulating resin adhesive 3, or as shown in FIG. 16. In terms of forming the recess 3c directly above the conductive particles 2 in the insulating resin adhesive 3, the minimum melt viscosity is preferably 1500 Pa · s or more, more preferably 2000 Pa · s or more, and further preferably 3000 ~ 15000Pa‧s, particularly preferably 3000 ~ 10000Pa‧s. Regarding this minimum melt viscosity, as an example, a rotary rheometer (manufactured by TA instrument Co., Ltd.) can be used to keep the temperature constant at a temperature increase rate of 10 ° C./minute and a measurement pressure of 5 g, and use a measuring plate with a diameter of 8 mm Out. When the step of pressing the conductive particles 2 into the insulating resin adhesive 3 is performed at preferably 40 to 80 ° C, and more preferably 50 to 60 ° C, the recessed portion 3b or 3c is formed in the same manner as described above. In terms of the lower limit of the viscosity at 60 ° C, it is preferably 3000 Pa · s or more, more preferably 4000 Pa · s or more, and further preferably 4500 Pa · s or more. The upper limit is preferably 20,000 Pa · s or less, and more preferably 15000 Pa. ‧S or less, more preferably 10,000Pa · s or less.

By setting the viscosity of the resin constituting the insulating resin adhesive 3 to a high viscosity as described above, when an anisotropic conductive film is used, conductive particles 2 are sandwiched between connection objects such as opposing electronic parts. In the case of heating and pressing, the conductive particles 2 in the anisotropic conductive film can be prevented from flowing away due to the flow of the molten insulating resin adhesive 3.

(Thickness of insulating resin adhesive)

The thickness La of the insulating resin adhesive 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. In addition, in terms of the relationship between the thickness La of the insulating resin adhesive 3 and the average particle diameter D of the conductive particles 2, the ratio (La / D) of these is preferably 0.6 to 10. If the thickness La of the insulating resin adhesive 3 is too large, the conductive particles will be easily dislocated during anisotropic conductive connection, and the catchability of the conductive particles in the terminal will be reduced. When La / D exceeds 10, this tendency becomes remarkable. Therefore, La / D is preferably 8 or less, and more preferably 6 or less. Conversely, if the thickness La of the insulating resin adhesive 3 is too small and La / D is less than 0.6, it is difficult to maintain the conductive particles in a specific particle dispersion state or a specific arrangement by the insulating resin adhesive 3. Especially when the connection terminal is a high-density COG, the ratio (La / D) of the layer thickness La of the insulating resin adhesive 3 to the particle diameter D of the conductive particles 2 is preferably 0.8 to 2.

(Embedded state of conductive particles in insulating resin adhesive)

The embedded state of the conductive particles 2 in the insulating resin adhesive 3 is not particularly limited, and anisotropic conductive connections are made by holding an anisotropic conductive film between opposing parts and applying heat and pressure. In this case, it is preferable to expose the conductive particles 2 from the insulating resin adhesive 3 as shown in FIG. 14 and FIG. 15 to the surface 3a of the insulating resin adhesive at the central portion between the adjacent conductive particles 2. A tangent plane 3p to form a recess 3b around the exposed portion of the conductive particles 2, or an insulating resin adhesive directly above the conductive particles 2 pressed into the insulating resin adhesive 3 as shown in FIG. 16 Partly, the recessed portion 3c is formed with respect to the same tangent plane 3p as described above, so that the surface of the insulating resin adhesive 3 immediately above the conductive particles 2 is undulated. For the flattening of the conductive particles 2 generated when the conductive particles 2 are held between the electrodes of the opposing electronic parts and heated and pressurized, the presence of the recessed portions 3b shown in FIG. 14 and FIG. 15 and the absence of the recessed portions As compared with the case of 3b, the resistance of the conductive particles 2 from the insulating resin adhesive 3 is reduced. Therefore, it becomes easy to hold the conductive particles 2 between the opposing electrodes, and the conduction performance is also improved. Further, in the resin constituting the insulating resin adhesive 3, by forming the recessed portion 3c (FIG. 16) on the surface of the resin directly above the conductive particles 2, the pressure at the time of heating and pressing is changed compared to the case where the recessed portion 3c does not exist. It becomes easy to concentrate on the conductive particles 2, and it becomes easy to hold the conductive particles 2 in the electrode, and the conduction performance is improved.

In terms of easily obtaining the above-mentioned effects of the recessed portions 3b and 3c, the ratio of the maximum depth Le of the recessed portions 3b (Figures 14 and 15) around the exposed portion of the conductive particles 2 to the average particle diameter D of the conductive particles 2 (Le / D) is preferably less than 50%, more preferably less than 30%, and still more preferably 20 to 25%. The maximum diameter Ld of the concave portion 3b (Figures 14 and 15) around the exposed portion of the conductive particle 2 is The ratio (Ld / D) of the average particle diameter D of the conductive particles 2 is preferably 100% or more, more preferably 100 to 150%. The maximum depth Lf of the resin recess 3c (FIG. 14) directly above the conductive particles 2 and The ratio (Lf / D) of the average particle diameter D of the conductive particles 2 is preferably greater than 0, and preferably less than 10%, and more preferably less than 5%.

The diameter Lc of the exposed portion of the conductive particles 2 may be equal to or smaller 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 adhesive 3, and the diameter Lc may be zero.

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

In terms of easily obtaining the effect of the above-mentioned recessed portion 3b, the ratio (Lb / D) of the distance between the tangent plane 3p and the deepest portion of the conductive particle 2 (hereinafter referred to as the embedding amount) Lb to the average particle diameter D of the conductive particle 2 (Hereinafter referred to as the 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 or adhesion from the resin constituting the insulating resin adhesive 3 may be laminated on the insulating resin adhesive 3 in which the conductive particles 2 are arranged.

In the case where the above-mentioned recessed portion 3b is formed by the insulating resin adhesive 3, as shown in the anisotropic conductive film 1d shown in FIG. As shown in the anisotropic conductive film 1e shown in FIG. 18, the surface may be laminated on the surface opposite to the surface on which the recessed portion 3b is formed. The same applies when the recessed portion 3 c is formed in the insulating resin adhesive 3. By laminating the insulating adhesive layer 4, when an anisotropic conductive film is used for anisotropic conductive connection of electronic parts, the space formed by the electrodes or bumps of the electronic parts can be filled to improve adhesion.

When the insulating adhesive layer 4 is laminated on the insulating resin adhesive 3, the insulating adhesive layer 4 is preferably located on the IC chip regardless of whether or not the insulating adhesive layer 4 is on the formation surface of the recesses 3b, 3c. The first electronic component side (in other words, the insulating resin adhesive 3 is located on the second electronic component side such as a substrate). Thereby, inadvertent movement of the conductive particles can be avoided, and the capture property can be improved. In addition, the first electronic component such as an IC chip is usually set as a pressing jig side, the second electronic component such as a substrate is set as a stage side, and the anisotropic conductive film and the second electronic component are temporarily pressed, and then the first The electronic part is formally crimped to the second electronic part. However, according to the size of the thermocompression bonding area of the second electronic part, the anisotropic conductive film is temporarily attached to the first electronic part, and then the first electronic part and the second electronic part Electronic parts are formally crimped.

As the insulating adhesive layer 4, a known anisotropic conductive film can be appropriately selected and used as the insulating adhesive layer. The insulating adhesive layer 4 may also be used in combination with the above-mentioned insulating tree. Fatty Adhesive 3 is the same resin and further adjusted to a lower viscosity. The more the minimum melting viscosity of the insulating adhesive layer 4 and the insulating resin adhesive 3 is different, the easier it is to fill the space formed by the electrodes or bumps of the electronic component with the insulating adhesive layer 4, and it is expected to improve the The effect of sex. Moreover, the more this difference is, the smaller the amount of movement of the resin constituting the insulating resin adhesive 3 during anisotropic conductive connection is, and therefore, the catchability of the conductive particles of the terminal is more easily improved. Practically speaking, the minimum melt viscosity of the insulating adhesive layer 4 and the insulating resin adhesive 3 is preferably 2 or more, more preferably 5 or more, and even more preferably 8 or more. On the other hand, if the ratio is too large, when a long-sized anisotropic conductive film is made into a roll, there is a possibility that resin overflow or blocking may occur, so it is preferably 15 in practical use. the following. More specifically, the preferable 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 even more preferably 100 to 2000 Pa · s.

As a method of forming the insulating adhesive layer 4, a coating composition containing the same resin as that of the resin forming the insulating resin adhesive 3 can be formed by a coating method, dried, or further hardened, or can be prepared in advance. The film is formed by a known 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.

In addition, the minimum melt viscosity of the entire anisotropic conductive film formed by combining the insulating resin adhesive 3 and the insulating adhesive layer 4 also depends on the ratio of the thickness of the insulating resin adhesive 3 and the insulating adhesive layer 4, which is practical. It can be set to 8000Pa‧s or less. In order to easily fill the bumps, it can be 200 ~ 7000Pa‧s, preferably 200 ~ 4000Pa‧s.

Furthermore, if necessary, an insulating filler such as silicon dioxide fine particles, alumina, or aluminum hydroxide may be added to the insulating resin adhesive 3 or the insulating adhesive layer 4. Of insulating filler The blending amount 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 layers. Thereby, even when the anisotropic conductive film is melted during the anisotropic conductive connection, it is possible to suppress unnecessary movement of the conductive particles caused by the molten resin.

<Manufacturing method of anisotropic conductive film>

As a method for manufacturing an anisotropic conductive film, for example, a transfer mold for arranging conductive particles in a specific arrangement is manufactured, and the concave portions of the transfer mold are filled with conductive particles to make an insulating resin adhesive formed on a release film. 3 is applied thereon and 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. Alternatively, an insulating adhesive layer 4 is laminated on the conductive particles 2. In this way, an anisotropic conductive film 1A can be obtained.

After the conductive mold particles are filled in the concave portion of the transfer mold, the insulating resin adhesive agent is coated thereon, the conductive particles are transferred from the transfer mold to the surface of the insulating resin adhesive agent, and the conductive resin particles are electrically conductive. The particles are pressed into the insulating resin adhesive, whereby an anisotropic conductive film can be produced. The embedding amount (Lb) of the conductive particles can be adjusted by the pressing pressure and temperature during the pressing. In addition, the shape and depth of the concave portions 3b and 3c can be adjusted by the viscosity, the pressing speed, and the temperature of the insulating resin adhesive at the time of the pressing. For example, the lower limit of the viscosity of the insulating resin adhesive when the conductive particles are pressed is preferably 3000 Pa · s or more, more preferably 4000 Pa · s or more, and even more preferably 4500 Pa · s or more, and the upper limit is more preferably 20,000 Pa · s or less, more preferably 15,000 Pa · s or less, and even more preferably 10,000 Pa · s or less. Such a viscosity can be obtained at a temperature of preferably 40 to 80 ° C, more preferably 50 to 60 ° C. More specifically, when the anisotropic conductive film 1a having the concave portion 3b shown in FIG. 14 on the surface of the insulating resin adhesive is manufactured, it is preferable to set the viscosity of the insulating resin adhesive when the conductive particles are pressed in. 8000Pa‧s (50 ~ 60 ℃), used in manufacturing tools In the case of the anisotropic conductive film 1c of the recessed portion 3c shown in FIG. 16, the viscosity of the insulating resin adhesive when the conductive particles are pressed is preferably set to 4500 Pa · s (50 to 60 ° C).

In addition, as the transfer mold, in addition to those in which the conductive particles are filled in the recessed portions, a microadhesive agent is provided on the top surface of the convex portion and the conductive particles are adhered to the top surface.

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

In addition, as a method of arranging the conductive particles in a specific arrangement, a method using a biaxially stretched film or the like may be used instead of a method using a transfer mold.

<Package body>

The anisotropic conductive film is preferably made of a film package formed by being wound on a reel in order to be continuously used for connection of electronic parts. The length of the film roll may be 5 m or more, and preferably 10 m or more. There is no upper limit in particular, and in terms of the operability of the cargo, it is preferably 5,000 m or less, more preferably 1000 m or less, and still more preferably 500 m or less.

The film package may be formed by connecting an anisotropic conductive film shorter than the full length by a connecting tape. There may be multiple connection sites, they may exist regularly, or they may exist randomly. The thickness of the connecting tape is not particularly limited as long as it does not hinder performance, but if it is too thick, it may affect resin overflow or adhesion, so it is preferably 10 to 40 μm. The width of the film is not particularly limited, and is, for example, 0.5 to 5 mm.

According to the film roll body, continuous anisotropic conductive connection can be realized, which helps to reduce the cost of the connection body.

<Connection structure>

The anisotropic conductive film according to the present invention is used for the first step of FPC, IC chip, IC module, etc. by heat or light. An electronic component can be preferably applied to an anisotropic conductive connection with a second electronic component such as an FPC, a rigid substrate, a ceramic substrate, a glass substrate, or a plastic substrate. In addition, the IC chips or IC modules may be stacked to anisotropically conductively connect the first electronic components. The connection structure thus obtained and the manufacturing method thereof are also part of the present invention.

As a method of connecting an electronic component using an anisotropic conductive film, in terms of improving connection reliability, for example, it is preferable to temporarily paste the interface of the anisotropic conductive film in the thickness direction of the conductive particles close to the side where it exists. The second electronic component such as a wiring board is equipped with a first electronic component such as an IC chip on the temporarily-anisotropic conductive film, and is thermocompression-bonded from the first electronic component side. In addition, the connection may be performed by photocuring. Furthermore, in this connection, in terms of connection operation efficiency, it is preferable to align the long-side direction of the terminal of the electronic component with the short-side direction of the anisotropic conductive film.

Examples

Experimental example 1 to experimental example 8

(Fabrication of anisotropic conductive film)

Regarding the anisotropic conductive film used for the COG connection, the influence of the resin composition of the insulating resin adhesive and the arrangement of the conductive particles on the film formation performance and the conduction characteristics were studied in the following manner.

First, a resin composition for forming an insulating resin adhesive and an insulating adhesive layer was prepared using the compositions shown in Table 1. In this case, the minimum melt viscosity of the resin composition is adjusted by the preparation conditions of the insulating resin composition. The resin composition forming the insulating resin adhesive was coated on a PET film having a film thickness of 50 μm by a bar coater, and dried in an oven at 80 ° C. for 5 minutes, and the PET film was formed as shown in Table 2 An insulating resin adhesive layer having a thickness of La. In the same manner, an insulating adhesive layer was formed on the PET film at a thickness shown in Table 2.

Then, the mold was produced such that the arrangement of the conductive particles in a plan view became the arrangement shown in Table 2 and the distance between the centers of the repeating units closest to the conductive particles was 6 μm. The pellets of a known transparent resin were poured into the mold in a molten state, and cooled to solidify, thereby forming a resin mold having a recessed portion having the configuration shown in Table 2. Here, in Experimental Example 8, the arrangement of the conductive particles was set to a hexagonal lattice arrangement (number density: 32,000 particles / mm ² ), and one of the lattice axes was inclined with respect to the long side direction of the anisotropic conductive film by 15 °.

Metal-coated resin particles (Sekisui Chemical Industry Co., Ltd., AUL703, average particle diameter: 3 μm) were prepared as conductive particles, and the conductive particles were filled in a recess of a resin mold, and the above-mentioned insulating resin adhesive was coated thereon. At 60 ° C. and 0.5 MPa, they were bonded together by pressing. Then, the insulating resin adhesive is peeled from the mold, and the conductive particles on the insulating resin adhesive are pressurized (pressing conditions: 60 to 70 ° C, 0.5 MPa), thereby pressing them into the insulation. In the edge resin adhesive, a film in which conductive particles are embedded in the insulating resin adhesive in a state shown in Table 2 is produced. In this case, the embedded state of the conductive particles is controlled according to the pressing conditions. As a result, in Experimental Example 4, the shape of the film was not maintained after the conductive particles were pressed. In the other experimental examples, a film with conductive particles embedded therein could be produced. In observation with a metal microscope, as shown in Table 2, a concave portion was observed around the exposed portion of the buried conductive particles or directly above the buried conductive particles. In addition, in each of the experimental examples other than Experimental Example 4, a recessed portion around the exposed portion of the conductive particles and a recessed portion directly above the conductive particles were observed. Table 4 shows the most clearly observed for each experimental example. The measured value of the concave part.

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

(Evaluation)

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

(a) Initial on resistance

The anisotropic conductive film of each experimental example was held between a glass substrate on a stage and an IC for conducting characteristic evaluation on the side of the pressing tool, and the pressing and heating (180 ° C, 5 seconds) were performed to obtain each evaluation. With linker. In this case, the thrust obtained by pressing the tool was changed to three stages of low (40 MPa), medium (60 MPa), and high (80 MPa), and three types of connectors for evaluation were obtained.

Here, regarding the IC for conducting characteristic evaluation and a glass substrate, these terminal patterns correspond, and the dimensions are as follows. When the evaluation IC and the glass substrate are connected, the long-side direction of the anisotropic conductive film is aligned with the short-side direction of the bump.

IC for conducting characteristic evaluation

Shape: 1.8 × 20.0mm

Thickness: 0.5mm

Bump specifications: size 30 × 85μm, distance between bumps 50μm, bump height 15μm

Glass substrate (ITO wiring)

Glass material: 1737F manufactured by Corning

Shape: 30 × 50mm

Thickness: 0.5mm

Electrode: ITO wiring

The initial on-resistance of the obtained evaluation connector was measured and evaluated in accordance with the following three-stage evaluation criteria.

Evaluation criteria for initial on-resistance (practical, as long as it is less than 2Ω, there is no problem)

A: less than 0.4Ω

B: 0.4Ω or more and less than 0.8Ω

C: 0.8Ω or more

(b) Continuity reliability

A reliability test was carried out by placing the connector for evaluation prepared in (a) in a constant temperature bath at a temperature of 85 ° C and a humidity of 85% RH for 500 hours. The on-resistance after the same measurement as the initial on-resistance was measured. The evaluation criteria of each stage are evaluated.

Evaluation Criteria for Continuity Reliability (Practical, as long as it is less than 5Ω, there is no problem)

A: less than 1.2Ω

B: 1.2Ω or more and less than 2Ω

C: 2Ω or more

As can be seen from Table 2, in Experimental Example 4 where the lowest melting viscosity of the insulating resin layer was 800 Pa · s, it was difficult to form a film having a recessed portion in the insulating resin adhesive near the conductive particles. On the other hand, it can be seen that in the experimental example in which the minimum melting viscosity of the insulating resin adhesive is 1500 Pa · s or more, protrusions can be formed near the conductive particles of the insulating resin adhesive by adjusting the conditions when the conductive particles are embedded. And the anisotropic conductive film thus obtained has good conduction characteristics when used for COG. In addition, it can be seen that in Experimental Examples 1 to 7 in which the number density of conductive particles is lower than that in Experimental Example 8 of hexagonal lattice arrangement, anisotropic conductive connection can be performed at a lower pressure.

(c) Short circuit occurrence rate

Anisotropic conductive films of Experimental Examples 1 to 3 and 5 to 8 were used, and the following evaluation ICs for short-circuit occurrence rates were used to obtain evaluation connectors under the connection conditions of 180 ° C, 60 MPa, and 5 seconds, and the evaluation obtained by measurement The number of short circuits of the connected object is used to determine the short circuit occurrence rate as a ratio of the number of short circuits measured to the number of terminals of the evaluation IC.

IC for evaluating short-circuit occurrence rate (comb-teeth TEG (test element group in 7.5 μm space):

Shape: 15 × 13mm

Thickness: 0.5mm

Bump specifications: size 25 × 140μm, distance between bumps 7.5μm, bump height 15μm

As long as the short circuit is less than 50 ppm, it is practically preferable. The anisotropic conductive films of Experimental Examples 1 to 3 and 5 to 8 all do not reach 50 ppm.

Furthermore, for each of the experimental examples other than Experimental Example 4, the conductive particles captured by each bump were measured, and as a result, more than 10 conductive particles were captured.

Experimental Examples 9 ~ 16

(Fabrication of anisotropic conductive film)

Regarding the anisotropic conductive film used for FOG connection, the influence of the resin composition of the insulating resin adhesive and the arrangement of the conductive particles on the film formation performance and the conduction characteristics were studied in the following manner.

That is, a resin composition for forming an insulating resin adhesive and an insulating adhesive layer was prepared with the composition shown in Table 3, and an anisotropic conductive film was produced in the same manner as in Experimental Example 1 using these. The arrangement of the conductive particles in this case and the distance between the centers closest to the conductive particles are shown in Table 4. In Experimental Example 16, the arrangement of the conductive particles was set to a hexagonal lattice arrangement (number density 15000 pieces / mm ² ), and one of the lattice axes thereof was inclined 15 ° with respect to the long-side direction of the anisotropic conductive film.

In the manufacturing step of the anisotropic conductive film, after the conductive particles were pressed into the insulating resin adhesive, the film shape was not maintained in Experimental Example 12, and the film shape was maintained in other experimental examples. Therefore, for the anisotropic conductive film of the experimental example other than the experimental example 12, the buried state of the conductive particles was observed and measured with a metal microscope, and the following evaluations were performed. Table 4 shows the embedded state of the conductive particles in each experimental example. The embedding conditions shown in Table 4 are the same as those in Table 2, and are measured values in which the recessed portion of the insulating resin adhesive is most clearly observed for each experimental example.

(Evaluation)

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

(a) Initial on resistance

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

Evaluation FPC:

Terminal pitch: 20μm

Terminal width / space between terminals: 8.5μm / 11.5μm

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

Alkali-free glass substrate:

Electrode: ITO wiring

Thickness: 0.7mm

Evaluation criteria for initial on-resistance

A: less than 1.6Ω

B: 1.6Ω or more and less than 2.0Ω

C: 2.0Ω or more

(b) Continuity reliability

The connection for evaluation prepared in (a) was left in a constant temperature bath at a temperature of 85 ° C and a humidity of 85% RH for 500 hours, and the on-resistance after the same measurement as the initial on-resistance was measured. The evaluation was performed in three stages according to the following criteria. Measurements.

Evaluation criteria for continuity reliability

A: less than 3.0Ω

B: 3.0Ω or more and less than 4Ω

C: 4.0Ω or more

As can be seen from Table 4, in Experimental Example 12 in which the minimum melt viscosity of the insulating resin layer was 800 Pa · s, it was difficult to form a film having a concave portion. On the other hand, it can be seen that in the experimental example in which the minimum melting viscosity of the insulating resin layer is 1500 Pa · s or more, a recessed portion can be formed near the conductive particles of the insulating resin adhesive by adjusting the conditions when the conductive particles are embedded. The anisotropic conductive film obtained in this way has good conduction characteristics when used in FOG.

(c) Short circuit occurrence rate

Measure the number of short circuits in the connector for evaluation of the measured initial on-resistance. The number of short circuits obtained and the number of gaps in the connection for evaluation were used to determine the short circuit occurrence rate. As long as the short-circuit occurrence rate does not reach 100 ppm, there is no practical problem.

The short-circuit occurrence rates of Experimental Examples 9-11 and 13-16 did not reach 100 ppm.

Furthermore, for each of the experimental examples other than Experimental Example 12, the conductive particles captured by each bump were measured, and as a result, more than 10 conductive particles were captured.

Claims (10)

An anisotropic conductive film includes conductive particles arranged in an insulating resin adhesive, and a polygonal repeating unit is repeatedly arranged in a plan view. The polygonal repeating unit sequentially connects the centers of a plurality of conductive particles. It is formed that the polygon of the repeating unit has a side diagonally intersecting with the long side direction or the short side direction of the anisotropic conductive film. For example, in the anisotropic conductive film according to the first patent application, the repeating unit is disposed on one side of the anisotropic conductive film. For example, the anisotropic conductive film according to item 1 or 2 of the patent application scope, wherein the repeating unit is trapezoidal. For example, the anisotropic conductive film according to any one of claims 1 to 3, wherein each side of the polygon forming the repeating unit is diagonally intersected with the long side direction or the short side direction of the anisotropic conductive film. For example, the anisotropic conductive film according to any one of claims 1 to 3, wherein the polygons forming the repeating unit have the sides in the long side direction or the short side direction of the anisotropic conductive film. For example, if the anisotropic conductive film according to any one of claims 1 to 5 is applied, when the polygon is reversed with one side of the polygon constituting the repeating unit as the center, the reversed repetition is repeated. One side of the polygon of the unit overlaps one side of the repeating unit adjacent before the inversion. For example, 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. For example, 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 the vertices of the hexagons when the regular hexagons are arranged without gaps. A connection structure with the anisotropy of any one of claims 1 to 8 in the scope of patent application The conductive film performs anisotropic conductive connection between the first electronic component and the second electronic component. A manufacturing method of a connection structure, which manufactures a connection structure of a first electronic component and a second electronic component by thermocompression bonding a first electronic component and a second electronic component through an anisotropic conductive film, and uses the application The anisotropic conductive film according to any one of the patent scopes 1 to 8 is used as the anisotropic conductive film.