KR102519781B1 - Anisotropic electroconductive film - Google Patents

Abstract

In the anisotropic conductive film, the insulating resin layer 2 contains, as conductive particles, 1A of high-hardness conductive particles having a 20% compressive elastic modulus of 8000 to 28000 N/mm 2 and a compressive elastic modulus higher than that of the high-hardness conductive particles 1A by 20%. It has a structure in which the low hardness conductive particles 1B are dispersed. The number density of all the conductive particles is 6000 pieces/mm 2 or more, and the number density of the low-hardness conductive particles 1B is 10% or more of the total number of conductive particles.

Description

Anisotropic conductive film {ANISOTROPIC ELECTROCONDUCTIVE FILM}

The present invention relates to an anisotropic conductive film.

BACKGROUND OF THE INVENTION Anisotropic conductive films in which conductive particles are dispersed in an insulating resin layer are widely used for mounting electronic components such as IC chips. However, if an oxide film is formed on the surface of the terminal of an electronic component connected by an anisotropic conductive film, connection resistance will become high. In this regard, reduction in resistance is achieved by tearing the oxide film using conductive particles having different particle diameters (Patent Document 1), or by using hard conductive particles to make the conductive particles penetrate the wiring to increase the connection area. Aiming at low resistance (patent document 2) etc. are proposed.

Japanese Unexamined Patent Publication No. 2013-182823 Japanese Unexamined Patent Publication No. 2012-164454

As described in Patent Literature 1, when conductive particles having different particle diameters are used, particles smaller than particles having a larger particle diameter penetrate into the terminal, but it is difficult to achieve a sufficiently low resistance by this. In addition, when hard conductive particles are used as described in Patent Literature 2, it is necessary to crimp with high pressure during anisotropic conductive connection, and deformation or cracks may occur in the connection structure between the substrate and the IC chip obtained by anisotropic conductive connection. there is.

There are ways to reduce the number of conductive particles to prevent deformation or cracking, but reducing the number of conductive particles reduces the number of trapped conductive particles in the terminal, resulting in higher resistance or an increase in conduction resistance after connection.

In contrast, the present invention uses conductive particles of high hardness so that even terminals with an oxide film can be connected, enables crimping under low pressure conditions, and facilitates confirmation of capture of conductive particles in terminals. The object is to make it possible to achieve a reduction in resistance reliably.

According to the present inventors, when conductive particles having different hardness are mixed and used, contact pressure is concentrated on the high hardness conductive particles during anisotropic conductive connection, and the high hardness conductive particles tear the oxide film, and the low hardness conductive particles cause the high hardness conductive particles. Particles contribute to conduction by using cracks formed in the oxide film. Thus, even if the particle density of high-hardness conductive particles is lowered, both high-hardness conductive particles and low-hardness conductive particles contribute to conduction at the terminal, so conduction is achieved. Since the resistance is lowered and the particle density of the high-hardness conductive particles can be lowered, crimping with high pressure is unnecessary during anisotropic conductive connection, and the problem of deformation or cracking in the bonded structure can be solved. Furthermore, it was found that observation of the indentation of the conductive particles becomes easy by mixing and using the high-hardness conductive particles and the low-hardness conductive particles, and came up with the present invention.

That is, in the present invention, high-hardness conductive particles having a 20% compressive elastic modulus of 8000 to 28000 N/mm2 as conductive particles and low-hardness conductive particles having a compressive elastic modulus 20% lower than the high-hardness conductive particles are dispersed in the insulating resin layer, An anisotropic conductive film having a number density of all conductive particles of 6000/mm 2 or more and a number density of low-hardness conductive particles of 10% or more of the total number of conductive particles is provided.

According to the anisotropic conductive film of the present invention, even if an oxide film is formed on the surface of a terminal of an electronic component, the high-hardness conductive particles penetrate the oxide film, and the high-hardness conductive particles cause cracks formed in the oxide film to have low hardness. Since conductive particles also contribute to conduction in the terminal, conduction resistance can be reduced.

Further, by mixing the high-hardness conductive particles with the low-hardness conductive particles, the crimping force required for anisotropic conductive connection can be reduced compared to the case where the conductive particles consist only of the high-hardness conductive particles. Therefore, deformation or cracks can be prevented from occurring in the anisotropically conductively connected connection structure.

Furthermore, in the anisotropically conductively connected connection structure, indentations of both high-hardness conductive particles and low-hardness conductive particles can be observed, and in particular, indentations of high-hardness conductive particles can be observed clearly. The number of captured particles can be accurately evaluated. Therefore, resistance reduction can be achieved reliably.

1A is a plan view showing the arrangement of conductive particles in an anisotropic conductive film 10A according to an embodiment of the present invention.
1B is a cross-sectional view of an anisotropic conductive film 10A of an example.
2A is a plan view showing the arrangement of conductive particles in an anisotropic conductive film 10B according to an embodiment of the present invention.
2B is a cross-sectional view of an anisotropic conductive film 10B of an example.
3 is a cross-sectional view of an anisotropic conductive film 10C of an example.
4 is a cross-sectional view of an anisotropic conductive film 10D of an example.
5 is a cross-sectional view of an anisotropic conductive film 10E of an example.
6 is a cross-sectional view of an anisotropic conductive film 10F of an example.
7 is a cross-sectional view of an anisotropic conductive film 10G of an example.
8 is a cross-sectional view of an anisotropic conductive film 100A of an example.
9 is a cross-sectional view of an anisotropic conductive film 100B of an example.
10A is a cross-sectional view of an anisotropic conductive film 100C of an example.
10B is a cross-sectional view of an anisotropic conductive film 100C' of an example.
11 is a cross-sectional view of an anisotropic conductive film 100D of an example.
12 is a cross-sectional view of an anisotropic conductive film 100E of an example.
13 is a cross-sectional view of an anisotropic conductive film 100F of an example.
14 is a cross-sectional view of an anisotropic conductive film 100G of an example.
15 is a cross-sectional view of an anisotropic conductive film 100X for comparison.

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

<Overall configuration of anisotropic conductive film>

1A is a plan view illustrating the arrangement of conductive particles 1A and 1B in an anisotropic conductive film 10A of an embodiment of the present invention. 1B is an x-x sectional view of the anisotropic conductive film 10A.

This anisotropic conductive film 10A is composed of high-hardness conductive particles 1A having a 20% compressive elastic modulus of 8000 to 28000 N/mm 2 , and low-hardness conductive particles having a 20% compressive elastic modulus lower than that of the high-hardness conductive particles 1A ( Both sides of 1B) are formed of a conductive particle dispersion layer 3 dispersed in an insulating resin layer 2. The number density of all the conductive particles in which the high-hardness conductive particles 1A and the low-hardness conductive particles 1B are combined is 6000/mm2 or more, and among them, the number density of the low-hardness conductive particles 1B is 10% of the total conductive particles. occupies more than Although the entire conductive particles are in a tetragonal lattice arrangement, there is no regularity as to which of the high hardness conductive particles 1A and the low hardness conductive particles 1B are located at each lattice point.

<Conducting Particles>

In the conductive particle-dispersed layer 3, both high-hardness conductive particles 1A and low-hardness conductive particles 1B exist as conductive particles. Among them, the high-hardness conductive particles 1A have a 20% compressive elastic modulus of 8000 to 28000 N/mm 2 .

Here, the 20% compressive elastic modulus is obtained by measuring the amount of compressive deformation of the conductive particles when a compressive load is applied to the conductive particles using a micro compression tester (for example, Fischer Scope H-100 manufactured by Fischer Instruments),

A K value calculated by 20% compressive modulus (K) (N/mm 2 ) = (3/2 ^1/2 )·F·S ^-3/2 ·R ^-1/2 can be used.

during the ceremony,

F: Load value when the conductive particles are compressed and deformed by 20% (N)

S: Compression displacement when conductive particles are compressed by 20% (mm)

R : radius of conductive particle (mm)

am.

By setting the 20% compressive elastic modulus of the high-hardness conductive particles to 8000 N/mm2 or more, even if an oxide film is formed on the terminal surface of the electronic component, the oxide film can be torn by the high-hardness conductive particles, and is 28000 N/mm2 or less. This makes it possible to perform anisotropic conductive connection using a conventional pressing jig without excessively increasing the crimping force required at the time of anisotropic conductive connection.

The particle diameter of the high-hardness conductive particles 1A is preferably 1 μm or more and 30 μm or less, more preferably 3 μm or more and less than 10 μm, in order to suppress an increase in conduction resistance and also to suppress occurrence of a short circuit. The particle diameter of the conductive particles before being dispersed in the insulating resin layer can be measured with a general particle size distribution measuring device, and the average particle diameter can also be obtained using a particle size distribution measuring device. It may be an image type or a laser type. An example of the image-type measuring device is a wet flow type particle size/shape analyzer FPIA-3000 (Malvern Corporation). The number of samples for measuring the average particle diameter (D) (the number of conductive particles) is preferably 1000 or more. The particle diameter of the conductive particles in the anisotropic conductive film can be obtained through electron microscope observation such as SEM. In this case, it is preferable to set the number of samples for measuring the average particle diameter to 200 or more.

In the case of using conductive particles having insulating fine particles adhered to their surfaces, the particle diameter of the conductive particles in the present invention means a particle diameter that does not contain insulating fine particles on the surface.

On the other hand, the 20% compressive elastic modulus of the low-hardness conductive particles 1B is lower than that of the high-hardness conductive particles, and is preferably 10% or more and 70% or less of the 20% compressive elastic modulus of the high-hardness conductive particles. If the 20% compressive modulus of the low-hardness conductive particles 1B is too low, it will be difficult to contribute to conduction. Conversely, if it is too high, the hardness difference from the high-hardness conductive particles will be insufficient, making it impossible to obtain the effect of the present invention.

The particle size of the low-hardness conductive particles 1B is preferably 1 μm or more and 30 μm or less, and there is no practical problem if it is 80% or more of the particle size of the high-hardness conductive particles, but it is preferably equal or larger. By making the particle diameter of the low-hardness conductive particles equal or greater than that of the high-hardness conductive particles, the low-hardness conductive particles can easily contribute to conduction by utilizing cracks formed in the oxide film on the terminal surface by the high-hardness conductive particles.

The high-hardness conductive particles 1A and low-hardness conductive particles 1B having the above-described hardness and particle size can be appropriately selected from conductive particles used in known anisotropic conductive films. Examples thereof include metal particles such as nickel, cobalt, silver, copper, gold, and palladium, alloy particles such as solder, metal-coated resin particles, and metal-coated resin particles having insulating fine particles attached to the surface thereof. As for the thickness of the metal layer in metal-coated resin particle, 50 nm - 250 nm are preferable. Also, the conductive particles may have protrusions formed on the surface. In the case of metal-coated resin particles, you may use what is illustrated by Unexamined-Japanese-Patent No. 2016-89153.

<Number Density of Conductive Particles>

The number density of the low-hardness conductive particles 1B is 10% or more of the total conductive particles, and can be appropriately adjusted depending on the type of terminal to be connected and the connection conditions. As an example, it is preferably 20% or more and 80% or less, and more preferably 30% or more and 70% or less. Even if the number density of low-hardness conductive particles relative to the total number of conductive particles is too low or too high, it is difficult to obtain the effect of the present invention by mixing high-hardness conductive particles and low-hardness conductive particles.

The number density of the entire conductive particles is not particularly limited, but as an example, when the average particle diameter (D) of the entire conductive particles 1A and 1B is less than 10 µm, it is preferably 6000/mm2 or more and 42000 /mm2 or less. When the average particle size is 10 μm or more, it is not limited to this range. As an example, it is 20 pieces/mm 2 or more and 2000 pieces/mm 2 or less.

When the average particle diameter (D) of the entirety of the conductive particles 1A and 1B is less than 10 µm, and the number density of the entire conductive particles becomes excessively high, the area occupancy rate of the conductive particles calculated by the following formula also becomes excessively high.

area share

= [Number density of conductive particles (piece/mm2) when viewed from a plane] × [Average area of one conductive particle when viewed from a plane (mm2/piece)] × 100

The area occupancy rate is an index of the thrust required for the press jig to thermally compress the anisotropic conductive film to the electronic component. By setting this area occupancy to preferably 35% or less, more preferably within the range of 0.3 to 30%, it is possible to suppress the thrust required for the press jig to heat-compress the anisotropic conductive film to the electronic component.

In addition, the number density of conductive particles can be measured using an observation image by a metallurgical microscope or the like. Moreover, you may measure and obtain|require an observation image by image analysis software (For example, WinROOF, Mitani Corporation, etc.). In the case of obtaining the number density of conductive particles, a plurality of points (preferably 5 points or more, more preferably 10 points or more) are arbitrarily set as a rectangular area with a side of 100 μm or more, and the total area of the measurement area is 2 It is preferable to set it as mm<2> or more. The size and number of individual regions may be appropriately adjusted according to the state of number density. In addition, the average of the planar view area of one conductive particle can be obtained by measuring an observation image of the film surface using a metallographic microscope or an electron microscope such as SEM. You may use image analysis software. The observation method or measurement method is not limited to the above-mentioned method.

In addition, the overall distance Lg between the conductive particles 1A and 1B is appropriately set according to the predetermined number density and particle arrangement after achieving the area occupancy of the conductive particles 1A and 1B described above.

<Arrangement of conductive particles>

In the anisotropic conductive film of the present invention, the arrangement of all the conductive particles including the high-hardness conductive particles 1A and the low-hardness conductive particles 1B when viewed from the top of the film may be regular or random. . As an aspect of the regular arrangement, lattice arrangements such as a hexagonal lattice, a tetragonal lattice, and a rectangular lattice, in addition to the square lattice shown in FIG. 1A, are exemplified. Further, as the particle arrangement of the entire conductive particles, a row of particles in which the conductive particles 1A or 1B are arranged in a straight line at predetermined intervals may be arranged in parallel at predetermined intervals. In the present invention, the regular arrangement is not particularly limited as long as it is repeated in the longitudinal direction of the film.

On the other hand, each of the high-hardness conductive particles 1A and the low-hardness conductive particles 1B may be arranged regularly. For example, as in the anisotropic conductive film 10B shown in FIGS. 2A and 2B, the number density of the low-hardness conductive particles 1B is 50% of the total number of conductive particles, and the high-hardness conductive particles 1A and the low-hardness conductive particles 1A Each of the conductive particles 1B can be arranged in a tetragonal lattice arrangement. In Fig. 2A, the high-hardness conductive particles 1A and the low-hardness conductive particles 1B are alternately arranged, but the present invention includes such a strict arrangement as well as other arrangements.

When there is a lattice axis or an arrangement axis in the particle arrangement of the entire conductive particle, the lattice axis or arrangement axis may be parallel to the longitudinal direction of the anisotropic conductive film 10A, may intersect with the longitudinal direction of the anisotropic conductive film 10A, or be connected. It can be determined according to the terminal width, terminal pitch, etc. For example, in the case of an anisotropic conductive film for fine pitch, as shown in FIG. 1A, the lattice axis A of at least one of the conductive particles 1A and 1B meanders with respect to the longitudinal direction of the anisotropic conductive film 10A. It is preferable to set the angle θ between the longitudinal direction of the terminals 20 connected in the anisotropic conductive film 10A and the lattice axis A to 16° to 74°.

Further, it is preferable that the conductive particles 1A, 1B exist without contacting each other when viewed from the plane of the film, and that the conductive particles 1A, 1B also exist without overlapping each other in the film thickness direction. Therefore, the ratio of the number of conductive particles 1A, 1B in non-contact with each other to the total number of conductive particles is 95% or more, preferably 98% or more, and more preferably 99.5% or more. This is the same regardless of regular arrangement or random arrangement. As will be described later, it is preferable to arrange the conductive particles 1A, 1B regularly using a transfer type because the ratio of the conductive particles 1A, 1B to exist without contact with each other can be easily controlled. In the case of random arrangement, since it is easy to knead the conductive particles 1A and 1B with an insulating resin to produce an anisotropic conductive film, a production method using a transfer type and a production method using kneading can be considered in a balance between performance and cost. You may choose any of them.

When each conductive particle 1A, 1B exists without contacting each other, it is preferable that the position of the film thickness direction is uniform. For example, when the high-hardness conductive particles 1A and the low-hardness conductive particles 1B have the same particle diameter, as shown in FIG. 1B, the embedding amount Lb of the conductive particles 1A and 1B in the film thickness direction is can be done evenly. That is, since the distance from one interface of the insulating resin layer 2 can be made uniform, the ability to trap conductive particles in the terminal is easily stabilized.

Further, when the particle diameters of the high-hardness conductive particles 1A and the low-hardness conductive particles 1B are different, the insulating resin layer 2 is formed by embedding the conductive particles 1A and 1B in the insulating resin layer 2. If the distances from the surface of the terminal to the conductive particles 1A and 1B are the same, for the same reason as above, the trapping ability of the conductive particles in the terminal is likely to be stable. On the other hand, as shown in Fig. 3, when the conductive particles 1A and 1B are exposed from the insulating resin layer 2, each of the high hardness conductive particles 1A and the low hardness conductive particles 1B has insulating properties. The position of the film thickness direction of the top exposed from the resin layer 2 can also be made uniform. The relationship between the layer thickness La of the insulating resin layer 2 and the average particle diameter D of the conductive particles 1A and 1B (La/D) will be described later.

Whether the high-hardness conductive particles 1A and the low-hardness conductive particles 1B have the same or different diameters, if the conductive particles 1A and 1B are exposed from the insulating resin layer 2, the pressure applied during connection It becomes easy to spread to these conductive particles 1A, 1B. If the case of metal-coated resin particles is described in detail as an example, in the same way as the action of the indentations 2b and 2c described later, if the conductive particles 1A and 1B are exposed from the insulating resin layer 2, during anisotropic conductive connection Since the resistance of the insulating resin layer 2 to the deformation of the metal-coated resin particles caused by the pressing of the metal-coated resin particles by the pressing jig is reduced, the state of the indentation after connection is likely to be uniform. This makes it easy to check the state after connection.

Here, the embedding amount Lb is the surface of the insulating resin layer 2 in which the conductive particles 1A and 1B are embedded (among the front and back surfaces of the insulating resin layer 2, the conductive particles 1A and 1B are exposed). surface, or a surface close to the conductive particles 1A, 1B when the conductive particles 1A and 1B are completely embedded in the insulating resin layer 2), and the central portion between adjacent conductive particles means the distance between the tangential plane 2p and the deepest part of the conductive particles 1A and 1B. When the ratio of the embedding amount (Lb) to the average particle diameter (D) of the conductive particles 1A, 1B is the embedding rate (Lb/D), the embedding rate is preferably 30% or more and 105% or less.

When the embedding ratio (Lb/D) is set to 30% or more and less than 60%, the proportion of exposed particles from the relatively high-viscosity resin holding the conductive particles increases, so low-voltage mounting becomes easier. By setting it to 60% or more, it becomes easy to maintain the conductive particles 1A, 1B in a predetermined particle dispersion state or a predetermined arrangement by the insulating resin layer 2. In addition, by setting it to 105% or less, the amount of resin in the insulating resin layer, which acts to cause unnecessary flow of conductive particles between terminals during anisotropic conductive connection, can be reduced. In addition, the conductive particles 1A and 1B may penetrate the insulating resin layer 2, and the embedding ratio (Lb/D) in that case is 100%.

In the present invention, the value of the embedding ratio (Lb/D) is 80% or more, preferably 90% or more, more preferably 96% or more of the total number of conductive particles included in the anisotropic conductive film, It refers to the number of landfill rates (Lb/D). Therefore, the embedding rate of 30% or more and 105% or less means that the embedding rate of 80% or more, preferably 90% or more, more preferably 96% or more of the total number of conductive particles included in the anisotropic conductive film is 30% or more and 105%. says below In this way, since the embedding ratio (Lb/D) of all conductive particles is made uniform, the weight of the pressurization is uniformly applied to the conductive particles, so that the state of capturing the conductive particles in the terminal is improved, and reliability of conduction can be expected. can In order to further increase the accuracy, 200 or more conductive particles may be measured and determined.

In addition, the measurement of the embedding ratio (Lb/D) can be collectively obtained for a certain number of objects by adjusting the focus in a plane view image. Alternatively, a laser type discrimination displacement sensor (manufactured by Keyence Corporation, etc.) may be used for measuring the filling rate (Lb/D).

<Insulating resin layer>

(Viscosity of the insulating resin layer)

In the anisotropic conductive film of the present invention, the minimum melt viscosity of the insulating resin layer 2 is not particularly limited, and can be appropriately determined depending on the intended use of the anisotropic conductive film, the manufacturing method of the anisotropic conductive film, and the like. For example, depending on the manufacturing method of the anisotropic conductive film, it may be about 1000 Pa·s as long as the indentations 2b (FIG. 4) and 2c (FIG. 5) described later can be formed. On the other hand, as a method for producing an anisotropic conductive film, when conducting a method of holding conductive particles in a predetermined arrangement on the surface of an insulating resin layer and pressing the conductive particles into the insulating resin layer, the insulating resin layer can form a film. From this point of view, it is preferable to set the minimum melt viscosity of the insulating resin layer to 1100 Pa·s or more.

In addition, as described in the method for producing an anisotropic conductive film described later, as shown in FIG. 4 , recesses 2b are formed around the exposed portions of the conductive particles 1A and 1B press-inserted into the insulating resin layer 2. or, as shown in Fig. 5, from the viewpoint of forming the depressions 2c right above the conductive particles 1A and 1B press-fitted into the insulating resin layer 2, it is preferably 1500 Pa·s or more, more preferably is 2000 Pa·s or more, more preferably 3000 to 15000 Pa·s, still more preferably 3000 to 10000 Pa·s. This lowest melt viscosity can be determined using a rotational rheometer (manufactured by TA instruments) as an example, holding constant at a measuring pressure of 5 g, and using a measuring plate with a diameter of 8 mm, more specifically, temperature In the range of 30 to 200°C, the temperature rise rate is 10°C/min, the measurement frequency is 10 Hz, and the change in load on the measurement plate is 5 g.

By setting the minimum melt viscosity of the insulating resin layer 2 to a high viscosity of 1500 Pa·s or more, unnecessary movement of conductive particles can be suppressed when the anisotropic conductive film is crimped to an article, and particularly between terminals during anisotropic conductive connection. Conductive particles to be held can be prevented from flowing away by the flow of the resin.

Further, in the case where the conductive particle-dispersed layer 3 of the anisotropic conductive film 10A is formed by press-fitting the conductive particles 1A and 1B into the insulating resin layer 2, the conductive particles 1A and 1B are press-fitted. The insulating resin layer 2 at this time is, when the conductive particles 1A, 1B are pressed into the insulating resin layer 2 so that the conductive particles 1A, 1B are exposed from the insulating resin layer 2, the insulating resin layer ( 2) This plastic deformation results in a high-viscosity viscous body in which dents 2b (FIG. 4) are formed in the insulating resin layer 2 around the conductive particles 1A, 1B, or the conductive particles 1A, 1B When the conductive particles 1A, 1B are press-fitted so as to be embedded in the insulating resin layer 2 without being exposed from the insulating resin layer 2, the insulating resin layer 2 directly above the conductive particles 1A, 1B It is set as a viscous material having a high viscosity in which a depression 2c (Fig. 5) is formed on the surface. Therefore, the lower limit of the viscosity of the insulating resin layer 2 at 60°C is preferably 3000 Pa·s or more, more preferably 4000 Pa·s or more, still more preferably 4500 Pa·s or more, The upper limit is preferably 20000 Pa·s or less, more preferably 15000 Pa·s or less, still more preferably 10000 Pa·s or less. This measurement can be obtained by performing the same measurement method as for the lowest melt viscosity, and extracting a value at a temperature of 60°C.

The specific viscosity of the insulating resin layer 2 when the conductive particles 1A and 1B are press-fitted into the insulating resin layer 2 depends on the shape and depth of the depressions 2b and 2c to be formed, and preferably has a lower limit. is 3000 Pa s or more, more preferably 4000 Pa s or more, still more preferably 4500 Pa s or more, and the upper limit is preferably 20000 Pa s or less, more preferably 15000 Pa s or less, More preferably, it is 10000 Pa·s or less. Further, such a viscosity is preferably obtained at 40 to 80°C, more preferably at 50 to 60°C.

As described above, the depressions 2b (FIG. 4) are formed around the conductive particles 1A and 1B exposed from the insulating resin layer 2, so that when the anisotropic conductive film is pressed against the article, The resistance received from the insulating resin to the flattening of the conductive particles 1A and 1B produced is reduced compared to the case where there is no dent 2b. For this reason, when conducting anisotropic conductive connection, conductive particles are easily caught in the terminal, thereby improving the conduction performance and also improving the trapping property.

Further, by forming a dent 2c (FIG. 5) on the surface of the insulating resin layer 2 immediately above the conductive particles 1A, 1B which are not exposed from the insulating resin layer 2 and are filled in, the dent 2c (Fig. 5) is formed. Compared to the case without (2c), the pressure at the time of pressing the article of the anisotropic conductive film tends to be concentrated on the conductive particles 1A and 1B. For this reason, when conductive particles are easily caught in the terminal during anisotropic conductive connection, trapping properties are improved and conduction performance is improved.

<"slope" or "undulation" instead of indentation>

The "dents" 2b and 2c of the anisotropic conductive film as shown in Figs. 4 and 5 can also be explained from the viewpoint of "inclination" or "undulation". Below, it demonstrates, referring drawings (FIGS. 8-15).

The anisotropic conductive film 100A is composed of the conductive particle dispersion layer 3 (FIG. 8). In the conductive particle-dispersed layer 3, high-hardness conductive particles 1A and low-hardness conductive particles 1B are regularly dispersed in an exposed state on one side of the insulating resin layer 2. When viewed from the plane of the film, the conductive particles 1A and 1B are not in contact with each other, and the conductive particles 1A and 1B are regularly dispersed without overlapping each other in the film thickness direction as well. A single layer of conductive particles having uniform positions in the film thickness direction is constituted.

On the surface 2a of the insulating resin layer 2 around each of the conductive particles 1A and 1B, there is an inclination 2b with respect to the contact plane 2p of the insulating resin layer 2 in the central portion between adjacent conductive particles. ) is formed. As will be described later, in the anisotropic conductive film of the present invention, undulations 2c may be formed on the surface of the insulating resin layer immediately above the conductive particles 1A, 1B embedded in the insulating resin layer 2 ( 11, 13).

In the present invention, "inclination" means that the flatness of the surface of the insulating resin layer is impaired in the vicinity of the conductive particles 1A and 1B, and a part of the resin layer is missing with respect to the tangential plane 2p, and the amount of resin is reduced. means state. In other words, in the inclination, the surface of the insulating resin layer around the conductive particles is missing with respect to the tangent plane. On the other hand, "undulation" means a state in which the resin is reduced due to the presence of waviness on the surface of the insulating resin layer immediately above the conductive particles, and the presence of portions with height differences such as waviness. In other words, the amount of resin in the insulating resin layer immediately above the conductive particles is smaller than when it is assumed that the surface of the insulating resin layer directly above the conductive particles is in a tangential plane. These can be recognized by contrasting the portion corresponding directly above the conductive particle with the flat surface portion between the conductive particles (2f in FIGS. 11 and 13). In addition, there are cases where the starting point of the waviness exists as an inclination.

As described above, the inclination 2b (FIG. 8) is formed around the conductive particles 1A, 1B exposed from the insulating resin layer 2, so that at the time of anisotropic conductive connection, the conductive particles 1A, 1B, Since the resistance received from the insulating resin layer to the flattening of the conductive particles 1A and 1B generated when 1B) is held between the terminals is reduced compared to the case where there is no inclination 2b, the conductive particles are held between the terminals. By becoming easy to become, conduction performance improves, and trapping property improves. It is preferable that this inclination follows the outer shape of the conductive particles. This is because, besides the effect in connection being more easily expressed, it is easier to perform inspection and the like in the manufacture of the anisotropic conductive film by making it easier to recognize the conductive particles. Also, some of these inclinations and undulations may be lost by heat pressing to the insulating resin layer or the like, but the present invention includes this. In this case, the conductive particles may be exposed at one point on the surface of the insulating resin layer. In addition, since the anisotropic conductive film has a variety of electronic parts to be connected, and as long as it is tuned according to these, it is desired to have a high degree of freedom in design so that various requirements can be met, so it can be used even if the inclination or waviness is reduced or partially eliminated. there is.

Further, undulations 2c (Figs. 11 and 13) are formed on the surface of the insulating resin layer 2 directly above the conductive particles 1A and 1B that are filled without being exposed from the insulating resin layer 2. This makes it easy for the pressing force from the terminal to be applied to the conductive particles during anisotropic conductive connection, similar to the case of the inclination. In addition, since the amount of resin immediately above the conductive particles is reduced due to the presence of undulations compared to the case where the resin is deposited flat, it is easy to exclude the resin directly above the conductive particles during connection, and the terminal and the conductive particles are in contact. Since it becomes easy to do it, the trapping ability of the conductive particle in a terminal improves, and conduction reliability improves.

(Position of Conductive Particles in Thickness Direction of Insulating Resin Layer)

The position of the conductive particles 1A, 1B in the thickness direction of the insulating resin layer 2 when considering the viewpoint of "inclination" or "undulation" is the same as the above, the conductive particles 1A, 1B It may be exposed from the insulating resin layer 2 or may be embedded in the insulating resin layer 2 without being exposed, but the deepest part of the conductive particles from the tangential plane 2p in the central part between adjacent conductive particles It is preferable that the ratio (Lb/D) (hereinafter referred to as the embedding ratio) of the distance (hereinafter referred to as the embedding amount) (Lb) and the average particle diameter (D) of the conductive particles is 30% or more and 105% or less.

By setting the embedding ratio (Lb/D) to 30% or more, maintaining the conductive particles 1A, 1B in a predetermined particle dispersion state or a predetermined arrangement by the insulating resin layer 2, and setting the ratio to 105% or less In the case of anisotropic conductive connection, the amount of resin in the insulating resin layer, which acts to unnecessarily flow conductive particles between terminals, can be reduced.

The value of the embedding rate (Lb/D) is such that 80% or more, preferably 90% or more, and more preferably 96% or more of the total number of conductive particles included in the anisotropic conductive film is the embedding rate (Lb/D). D) means that it is a numerical value. Therefore, the embedding rate of 30% or more and 105% or less means that the embedding rate of 80% or more, preferably 90% or more, more preferably 96% or more of the total number of conductive particles included in the anisotropic conductive film is 30% or more and 105% or less. say that In this way, since the embedding ratio (Lb/D) of all conductive particles is uniform, the weight of the pressurization is uniformly applied to the conductive particles, so that the state of capturing the conductive particles in the terminal is improved and the reliability of conduction is improved. do.

The embedding rate (Lb/D) can be obtained by randomly extracting at least 10 areas with an area of 30 mm2 or more from the anisotropic conductive film, observing a part of the cross section of the film with a SEM image, and measuring a total of 50 or more conductive particles. In order to further increase the accuracy, 200 or more conductive particles may be measured and determined.

In addition, the measurement of the embedding ratio (Lb/D) can be collectively obtained for a certain number of objects by adjusting the focus in a plane view image. Alternatively, a laser type discrimination displacement sensor (manufactured by Keyence Corporation, etc.) may be used for measuring the filling rate (Lb/D).

(Form with a landfill rate of 30% or more and less than 60%)

As a more specific embedding mode of the conductive particles 1A, 1B having an embedding ratio (Lb/D) of 30% or more and less than 60%, first, as in the anisotropic conductive film 100A shown in FIG. 8, the conductive particles 1A, 1B ) is embedded at an embedding rate of 30% or more and less than 60% so that the insulating resin layer 2 is exposed. In this anisotropic conductive film 100A, a portion of the surface of the insulating resin layer 2 that is in contact with the conductive particles 1A and 1B exposed from the insulating resin layer 2 and the vicinity thereof is a barrier between adjacent conductive particles. It has an inclination 2b that becomes a ridge line generally following the outer shape of the conductive particles with respect to the tangent plane 2p on the surface 2a of the insulating resin layer at the central portion.

Such an inclination 2b or undulations 2c described later is produced by press-fitting the conductive particles 1A and 1B into the insulating resin layer 2 to form the anisotropic conductive film 100A, the conductive particles 1A, 1B) can be formed by press-fitting at 40 to 80°C with a viscosity of 3000 to 20000 Pa·s, more preferably 4500 to 15000 Pa·s.

(Form with a landfill rate of 60% or more and less than 100%)

As a more specific embedding mode of the conductive particles 1A, 1B having an embedding ratio (Lb/D) of 60% or more and less than 100%, first, as in the anisotropic conductive film 100A shown in FIG. 8, the conductive particles 1A, 1B ) is embedded at an embedding rate of 60% or more and less than 100% so that the insulating resin layer 2 is exposed. In this anisotropic conductive film 100A, a portion of the surface of the insulating resin layer 2 that is in contact with the conductive particles 1A and 1B exposed from the insulating resin layer 2 and the vicinity thereof is a barrier between adjacent conductive particles. It has an inclination 2b that becomes a ridge line generally following the outer shape of the conductive particles with respect to the tangent plane 2p on the surface 2a of the insulating resin layer at the central portion.

Such an inclination 2b or undulations 2c described later is produced by press-fitting the conductive particles 1A and 1B into the insulating resin layer 2 to form the anisotropic conductive film 100A, the conductive particles 1A, The lower limit of the viscosity at the time of press-fitting of 1B) is preferably 3000 Pa·s or more, more preferably 4000 Pa·s or more, still more preferably 4500 Pa·s or more, and the upper limit is preferably 20000 Pa·s or less, more preferably 15000 Pa·s or less, still more preferably 10000 Pa·s or less. Further, such a viscosity is preferably obtained at 40 to 80°C, more preferably at 50 to 60°C. In addition, by heat pressing the insulating resin layer, a part of the warp 2b or the undulations 2c may be lost, or the warp 2b may change to the undulations 2c, or may have the undulations 2c. The conductive particles may be exposed to the insulating resin layer 2 at one point at the top.

(Aspect of 100% landfill rate)

Next, among the anisotropic conductive films of the present invention, as in the aspect of the embedding rate (Lb/D) of 100%, as in the anisotropic conductive film 100B shown in FIG. Exposure diameter Lc of the conductive particles 1A and 1B exposed from the insulating resin layer 2, having an inclination 2b that becomes a ridge line generally following the outer shape of the conductive particle, the same as that of the anisotropic conductive film 100A shown in As with the anisotropic conductive film 100C shown in FIG. 10A , the inclination 2b around the exposed portion of the conductive particles 1A, 1B is smaller than the average particle diameter D of the conductive particles, and the conductive particles 1A, 1B ), and the exposure diameter (Lc) of the conductive particles (1A, 1B) and the average particle diameter (D) of the conductive particles are substantially the same, as in the anisotropic conductive film 100D shown in FIG. 11, the insulating number It is exemplified that the surface of the stratum 2 has shallow undulations 2c and the conductive particles 1A and 1B are exposed from the insulating resin layer 2 at one point of the top 1a.

Further, a minute protruding portion 2q is formed adjacent to the slope 2b of the insulating resin layer 2 around the exposed portion of the conductive particle and the undulations 2c of the insulating resin layer directly above the conductive particle. There may be. An example of this is shown in Fig. 10B.

Since these anisotropic conductive films 100B (FIG. 9), 100C (FIG. 10A), and 100D (FIG. 11) have a 100% embedding rate, the top 1a of the conductive particles 1A, 1B and the insulating resin layer 2 The surface 2a of is uniform to one surface. When the top 1a of the conductive particles 1A, 1B and the surface 2a of the insulating resin layer 2 are uniform, as shown in FIG. 8, the conductive particles 1A, 1B form an insulating resin layer ( 2) There is an effect that the amount of resin in the thickness direction of the film is less likely to be uneven around individual conductive particles during anisotropic conductive connection, and the movement of conductive particles due to resin flow can be reduced compared to the case where the conductive particles protrude from the surface. In addition, even if the embedding rate is not strictly 100%, the top 1a of the conductive particles 1A, 1B embedded in the insulating resin layer 2 and the surface 2a of the insulating resin layer 2 are flush with each other. If it is uniform, this effect can be obtained. In other words, when the embedding ratio (Lb/D) is approximately 80 to 105%, particularly 90 to 100%, the conductive particles 1A and 1B embedded in the insulating resin layer 2 have insulating properties from the top 1a The surface 2a of the resin layer 2 can be said to be flat, and the movement of the conductive particles due to the flow of the resin can be reduced.

Among these anisotropic conductive films (100B (FIG. 9), 100C (FIG. 10A), and 100D (FIG. 11)), since the amount of resin around the conductive particles 1A and 1B is less likely to be uneven in 100D, conduction by resin flow Since the movement of the particles can be eliminated, and the conductive particles 1A and 1B are exposed from the insulating resin layer 2 even at one point of the top 1a, the conductive particles 1A and 1B are captured at the terminal. It can be expected to have good properties and an effect that even a slight movement of conductive particles does not occur easily. Therefore, this aspect is particularly effective when the fine pitch or the space between bumps is narrow.

In addition, as will be described later, the anisotropic conductive films 100B (FIG. 9), 100C (FIG. 10A), and 100D (FIG. 11) having different shapes and depths of inclinations 2b and undulations 2c have conductive particles 1A , 1B) can be produced by changing the viscosity of the insulating resin layer 2 at the time of press-fitting.

(Form with a landfill rate of more than 100%)

Among the anisotropic conductive films of the present invention, when the embedding rate exceeds 100%, the conductive particles 1A and 1B are exposed as in the anisotropic conductive film 100E shown in FIG. 12, and the insulating resin layer around the exposed portions ( 2) that there is an inclination 2b with respect to the tangent plane 2p or a undulation 2c with respect to the tangent plane 2p of the insulating resin layer 2 directly above the conductive particles 1A and 1B (FIG. 13). can

Further, an anisotropic conductive film 100E (FIG. 12) having an inclination 2b in the insulating resin layer 2 around the exposed portions of the conductive particles 1A and 1B and immediately above the conductive particles 1A and 1B The anisotropic conductive film 100F (FIG. 13) having the undulations 2c in the insulating resin layer 2 has a viscosity of the insulating resin layer 2 when the conductive particles 1A and 1B are press-fitted in the production thereof. It can be manufactured by changing the back.

In addition, when the anisotropic conductive film 100E shown in FIG. 12 is used for anisotropic conductive connection, the conductive particles 1A and 1B are directly pressed from the terminal, so that the trapping ability of the conductive particles in the terminal is improved. Further, when the anisotropic conductive film 100F shown in FIG. 13 is used for anisotropic conductive connection, the conductive particles 1A and 1B do not directly press the terminals, but press them through the insulating resin layer 2, but in the pressing direction. 15 (that is, the conductive particles 1A and 1B are embedded with an embedding rate of more than 100%, the conductive particles 1A and 1B are not exposed from the insulating resin layer 2, and Since the surface of the insulating resin layer 2 is less than that in a flat state), pressing force is easily applied to the conductive particles, and the conductive particles 1A and 1B between the terminals move unnecessarily by the flow of the resin during anisotropic conductive connection. doing is hindered

The above-described inclination 2b of the insulating resin layer 2 around the exposed portion of the conductive particles (Figs. 8, 9, 10A, 12) and the undulations 2c of the insulating resin layer immediately above the conductive particles ) (FIGS. 11 and 13), the ratio (Le/D) of the maximum depth (Le) of the inclination 2b and the average particle diameter (D) of the conductive particles 1A, 1B is preferably It is preferably less than 50%, more preferably less than 30%, still more preferably 20 to 25%, and the maximum diameter Ld of the inclination 2b or waviness 2c and the average particle diameter of the conductive particles 1A, 1B ( The ratio (Ld/D) of D) is preferably 100% or more, more preferably 100 to 150%, and the maximum depth (Lf) of the undulations 2c and the average particle diameter of the conductive particles 1A, 1B ( The ratio (Lf/D) of D) is greater than 0, preferably less than 10%, and more preferably 5% or less.

Further, the diameter Lc of the exposed (immediately above) portion of the conductive particles 1A, 1B in the inclination 2b or the undulation 2c is equal to or smaller than the average particle diameter D of the conductive particles 1A, 1B. can be used, and is preferably 10 to 90% of the average particle diameter (D). The conductive particles 1A and 1B may be exposed at one positive point, or the conductive particles 1A and 1B may be completely embedded in the insulating resin layer 2 so that the diameter Lc becomes zero.

Further, as shown in FIG. 14 , in the anisotropic conductive film 100G having a buried ratio (Lb/D) of less than 60%, since the conductive particles 1A and 1B easily roll on the insulating resin layer 2, the anisotropic conductive film 100G From the viewpoint of improving the capture ratio at the time of conductive connection, it is preferable to set the embedding ratio (Lb/D) to 60% or more.

Further, in the aspect (Lb/D) in which the embedding rate exceeds 100%, when the surface of the insulating resin layer 2 is flat as in the anisotropic conductive film 100X of the comparative example shown in FIG. 15, the conductive particles 1A, 1B) and the amount of resin interposed between the terminal becomes excessively large. Further, since the conductive particles 1A and 1B press the terminals through the insulating resin layer without directly contacting and pressurizing the terminals, the conductive particles easily flow by the flow of the resin also by this.

In the present invention, the existence of the slopes 2b and undulations 2c on the surface of the insulating resin layer 2 can be confirmed by observing a cross section of the anisotropic conductive film with a scanning electron microscope, can also be checked. Observation of the inclination 2b and waviness 2c is possible even with an optical microscope or a metallographic microscope. In addition, the size of the inclination 2b and waviness 2c can be confirmed by focusing adjustment or the like at the time of image observation. As described above, it is the same even after reducing the inclination or waviness by heat press. Because there are cases where traces are left.

(Composition of insulating resin layer)

It is preferable to form the insulating resin layer 2 with a curable resin composition, and it can form, for example, with a thermally polymerizable composition containing a thermally polymerizable compound and a thermal polymerization initiator. The thermally polymerizable composition may contain a photopolymerization initiator as needed.

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

As a photoinitiator, you may contain multiple types reacting to light with a different wavelength. Thus, it is possible to use different wavelengths for photocuring of the resin constituting the insulating resin layer during production of the anisotropic conductive film and photocuring of the resin for bonding electronic components to each other during anisotropic conductive connection.

In photocuring at the time of manufacture of an anisotropic conductive film, all or one part of the photopolymerizable compound contained in an insulating resin layer can be photocured. By this photocuring, the arrangement of the conductive particles 1A and 1B in the insulating resin layer 2 is maintained or fixed, and short circuit suppression and capture improvement are expected. Moreover, you may adjust the viscosity of the insulating resin layer in the manufacturing process of an anisotropic conductive film suitably by this photocuring. In particular, this photocuring is preferably performed when the ratio (La/D) of the layer thickness (La) of the insulating resin layer 2 and the average particle diameter (D) of the conductive particles 1A and 1B is less than 0.6. Even when the layer thickness of the insulating resin layer 2 is small relative to the diameter of the conductive particles, the arrangement of the conductive particles in the insulating resin layer 2 is maintained or fixed more reliably, and the viscosity of the insulating resin layer 2 is adjusted This is because the decrease in yield in connection between electronic components using an anisotropic conductive film is suppressed.

30 mass % or less is preferable, as for the compounding quantity of the photopolymerizable compound in an insulating resin layer, 10 mass % or less is more preferable, and its less than 2 mass % is more preferable. It is because the thrust applied to the press-in at the time of connection will increase when there are too many photopolymerizable compounds.

Examples of the thermally polymerizable composition include a thermally radically polymerizable acrylate-based composition containing a (meth)acrylate compound and a thermal radical polymerization initiator, and a thermally cationic polymerizable epoxy-based composition containing an epoxy compound and a thermally cationic polymerization initiator. etc. can be mentioned. Instead of the thermal cationic polymerization epoxy composition containing a thermal cationic polymerization initiator, a thermal anionic polymerization epoxy composition containing a thermal anionic polymerization initiator may be used. Moreover, if it does not cause trouble in particular, you may use multiple types of polymeric compounds together. Examples of combined use include combined use of a cationically polymerizable compound and a radically polymerizable compound.

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

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

If the usage amount of the thermal radical polymerization initiator is too small, it results in poor curing, and if it is too large, the product life deteriorates. It is 5-40 mass parts.

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

As the thermal cationic polymerization initiator, those known as thermal cationic polymerization initiators of epoxy compounds can be employed, and for example, iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, etc. that generate acids by heat can be used. In particular, aromatic sulfonium salts exhibiting good temperature resistance can be preferably used.

The amount of the thermal cationic polymerization initiator tends to result in poor curing if the amount is too small, and the product life tends to decrease if the amount is too large. is 5 to 40 parts by mass.

The thermally polymerizable composition preferably contains a film forming resin or a silane coupling agent. Examples of the film-forming resin include phenoxy resins, epoxy resins, unsaturated polyester resins, saturated polyester resins, urethane resins, butadiene resins, polyimide resins, polyamide resins, polyolefin resins, and the like, two or more of these can be combined. Among these, a phenoxy resin can be preferably used from the viewpoint of film formability, workability, and connection reliability. It is preferable that a weight average molecular weight is 10000 or more. Moreover, as a silane coupling agent, an epoxy type silane coupling agent, an acrylic type silane coupling agent, etc. are mentioned. These silane coupling agents are mainly alkoxysilane derivatives.

In addition to the above-mentioned conductive particles 1A and 1B, an insulating filler may be contained in the thermally polymerizable composition for melt viscosity adjustment. As for this, a silica powder, an alumina powder, etc. are mentioned. Insulating filler A fine filler having a particle size of 20 to 1000 nm is preferable, and the compounding amount is preferably 5 to 50 parts by mass with respect to 100 parts by mass of a thermally polymerizable compound (photopolymerizable compound) such as an epoxy compound.

The anisotropic conductive film of the present invention may contain a filler, a softener, an accelerator, an anti-aging agent, a colorant (pigment, dye), an organic solvent, an ion catching agent, or the like, in addition to the insulating filler described above.

(layer thickness of insulating resin layer)

In the anisotropic conductive film of the present invention, the ratio (La/D) of the layer thickness (La) of the insulating resin layer 2 and the average particle diameter (D) of the conductive particles (1A, 1B) has a lower limit of 0.3 or more for reasons described later. , and the upper limit can be 10 or less. Therefore, the ratio is preferably from 0.3 to 10, more preferably from 0.6 to 8, still more preferably from 0.6 to 6. Here, the average particle diameter (D) of the conductive particles 1A and 1B means the average particle diameter. If the layer thickness La of the insulating resin layer 2 is too large, the conductive particles 1A, 1B are easily displaced by the flow of the resin during anisotropic conductive connection, and the conductive particles 1A, 1B in the terminal catchability is reduced. Since this tendency is remarkable when this ratio (La/D) exceeds 10, 8 or less is more preferable, and 6 or less is still more preferable. Conversely, when the layer thickness La of the insulating resin layer 2 is too small and the ratio (La/D) is less than 0.3, the conductive particles 1A and 1B are dispersed in a predetermined particle dispersion state by the insulating resin layer 2. Or, since it becomes difficult to maintain the predetermined arrangement, the ratio (La/D) is preferably 0.3 or more, and 0.6 or more from the viewpoint of reliably maintaining the predetermined particle dispersion state or predetermined arrangement by the insulating resin layer 2. more preferable than this Further, when the terminal to be connected is a high-density COG, the ratio (La/D) of the layer thickness (La) of the insulating resin layer 2 and the average particle diameter (D) of the conductive particles 1A, 1B is preferably 0.8 is ~ 2.

On the other hand, when the average particle diameter (D) is 10 μm or more, the upper limit of La/D is 3.5 or less, preferably 2.5 or less, more preferably 2 or less, and the lower limit is 0.8 or more, preferably Preferably greater than 1, more preferably greater than 1.3.

Regardless of the size of the average particle diameter D, if the layer thickness La of the insulating resin layer 2 is too large and this ratio becomes excessively large, it is difficult for the conductive particles 1A and 1B to be pressed against the terminal during anisotropic conductive connection. Together with the load, the flow of the resin facilitates the flow of the conductive particles. As a result, the conductive particles are easily displaced, and the trapping ability of the conductive particles in the terminal is deteriorated. In addition, the thrust required for the pressing jig to press the conductive particles to the terminal is also increased, which hinders low-voltage mounting. Conversely, if the layer thickness La of the insulating resin layer 2 is too small and this ratio is too small, it becomes difficult to hold the conductive particles 1A and 1B in a predetermined arrangement by the insulating resin layer 2.

<Deformation mode>

In the anisotropic conductive film of the present invention, a second insulating resin layer 4 having a lower minimum melt viscosity than the resin constituting the insulating resin layer 2 can be laminated on the conductive particle-dispersed layer 3 (FIG. 6 , Fig. 7). This second insulating resin layer 4 can fill a space formed by terminals such as bumps of electronic components at the time of anisotropic conductive connection, and can improve adhesion between opposing electronic components. That is, in order to enable low-voltage mounting of electronic components using an anisotropic conductive film and to suppress flow of the resin in the insulating resin layer 2 during anisotropic conductive connection to improve the particle trapping properties of the conductive particles 1A and 1B. For this reason, it is desirable to increase the viscosity of the insulating resin layer 2 and to reduce the thickness of the insulating resin layer 2 as long as the conductive particles 1A and 1B do not cause misalignment. If the thickness of ) is excessively thinned, the amount of resin for adhering the opposing electronic components to each other will be insufficient, so there is concern about deterioration in adhesiveness. On the other hand, by forming the second insulating resin layer 4 having a lower viscosity than the insulating resin layer 2 at the time of anisotropic conductive connection, the adhesiveness between electronic parts can also be improved, and the second insulating resin layer 4 Since the fluidity is higher than that of the insulating resin layer 2, it is possible to make it difficult to inhibit the pinching and press-fitting of the conductive particles 1A and 1B by the terminal.

In the case of laminating the second insulating resin layer 4 on the conductive particle-dispersed layer 3, regardless of whether or not the second insulating resin layer 4 is on the surface where the indentation 2b is formed, the electron pressurized by the tool It is preferable that the second insulating resin layer 4 is attached to the component (the insulating resin layer 2 is attached to the electronic component mounted on the stage). By doing in this way, unnecessary movement of the conductive particles can be avoided, and trapping performance can be improved.

The higher the difference between the minimum melt viscosity ratio between the insulating resin layer 2 and the second insulating resin layer 4, the easier it is to fill the space formed by the electrodes and bumps of the electronic component with the second insulating resin layer 4. , the adhesion between electronic parts can be improved. In addition, as this difference increases, the amount of movement of the insulating resin layer 2 present in the conductive particle-dispersed layer 3 becomes relatively small, and the conductive particles 1A and 1B between the terminals do not flow easily due to the flow of the resin. This is preferable because the trapping ability of the conductive particles 1A and 1B is improved. In terms of practical use, the minimum melt viscosity ratio between the insulating resin layer 2 and the second insulating resin layer 4 is preferably 2 or more, more preferably 5 or more, still more preferably 8 or more. On the other hand, if this ratio is too large, when the elongated anisotropic conductive film is made into a coiled body, there is a risk of resin protrusion or blocking, so for practical purposes, 15 or less is preferable. More specifically, the preferred minimum melt viscosity of the second insulating resin layer 4 satisfies the above-mentioned ratio and is 3000 Pa·s or less, preferably 2000 Pa·s or less, and particularly 100 to 2000 Pa. It is s.

In addition, the 2nd insulating resin layer 4 can be formed by adjusting the viscosity in the same resin composition as the insulating resin layer 2.

Moreover, the layer thickness of the 2nd insulating resin layer 4 is preferably 4-20 micrometers. Alternatively, it is preferably 1 to 8 times the average particle diameter (D) of the conductive particles 1A and 1B.

In addition, the minimum melt viscosity of the entire anisotropic conductive film 10F, 10G in which the insulating resin layer 2 and the second insulating resin layer 4 are combined is practically 8000 Pa s or less, preferably 200 to 7000 Pa s. s, more preferably 200 to 4000 Pa·s.

As a specific lamination mode of the second insulating resin layer 4, for example, as in the anisotropic conductive film 10F shown in FIG. 6, the conductive particles 1A and 1B protrude from one side of the insulating resin layer 2. In this case, the second insulating resin layer 4 is laminated on the protruding surface, and the conductive particles 1A and 1B can penetrate the second insulating resin layer 4. When the embedding ratio (Lb/D) of the conductive particles 1A and 1B is 0.95 or less, it is preferable to laminate the second insulating resin layer 4 in this way, and when it is 0.9 or less, it is more preferable. In addition, when the average particle diameter (D) is less than 10 μm, there are cases where it is preferable to do so.

On the other hand, as in the anisotropic conductive film 10G shown in FIG. 7 , the second insulating resin layer 4 may be laminated on the surface opposite to the surface of the insulating resin layer 2 in which the conductive particles 1A and 1B are embedded. do.

(Third insulating resin layer)

A third insulating resin layer may be formed on the opposite side with the second insulating resin layer 4 and the insulating resin layer 2 interposed therebetween. The third insulating resin layer can function as a tack layer. Similar to the second insulating resin layer 4, it may be formed to fill a space formed by electrodes or bumps of electronic components.

The resin composition, viscosity and thickness of the third insulating resin layer may be the same as or different from those of the second insulating resin layer 4 . The minimum melt viscosity of the anisotropic conductive film comprising the insulating resin layer 2, the second insulating resin layer 4, and the third insulating resin layer is not particularly limited, but for practical purposes, it is 8000 Pa s or less, preferably 200 to 7000 Pa·s, more preferably 200 to 4000 Pa·s.

<Method for producing anisotropic conductive film>

In the anisotropic conductive film of the present invention, for example, the conductive particles (1A, 1B) are maintained individually in a predetermined regular arrangement or in a random dispersed state on the surface of the insulating resin layer (2), and the conductive particles ( 1A, 1B) can be manufactured by press-fitting the insulating resin layer 2 with a flat plate or a roller.

Here, the embedding amount (Lb) of the conductive particles (1A, 1B) in the insulating resin layer 2 can be adjusted by the pressing force at the time of pushing the conductive particles (1A, 1B), the temperature, etc. The existence, shape and depth of 2b and 2c) can be adjusted by the viscosity of the insulating resin layer 2 at the time of press-in, press-in speed, temperature, etc.

In addition, the method for holding the conductive particles 1A, 1B in the insulating resin layer 2 is not particularly limited, but when the conductive particles 1A, 1B are regularly arranged, for example, a transfer type conductive particles (1A, 1B) mixed at a predetermined ratio are retained in the insulating resin layer (2). As the transfer type, for example, a transfer type material of inorganic materials such as silicon, various ceramics, metals such as glass and stainless steel, or organic materials such as various resins, by a known aperture forming method such as a photolithography method Opened ones can be used. In addition, the transfer type may take a shape such as a plate shape or a roll shape.

As a method for obtaining that the conductive particles (1A, 1B) of the insulating resin layer (2) are in a random dispersed state and not individually independent, the conductive particles (1A, 1B) are added to the resin composition forming the insulating resin layer (2). may be kneaded (mixed) at a predetermined ratio and applied onto a release film to obtain an insulating resin layer in which the conductive particles 1A and 1B are located at random positions.

In order to economically connect electronic components using an anisotropic conductive film, it is preferable that the anisotropic conductive film is a certain length. Therefore, the length of the anisotropic conductive film is preferably 5 m or more, more preferably 10 m or more, and still more preferably 25 m or more. On the other hand, if the anisotropic conductive film is excessively lengthened, the conventional connection device used in the case of manufacturing electronic components using the anisotropic conductive film becomes unusable, and the handleability is also poor. Therefore, the length of the anisotropic conductive film is preferably 5000 m or less, more preferably 1000 m or less, and even more preferably 500 m or less. Such a long body of the anisotropic conductive film is preferably wound around a core in view of excellent handling properties.

<How to use anisotropic conductive film>

The anisotropic conductive film of the present invention is preferably used when anisotropically conductively connecting a first electronic component such as an IC chip, an IC module, or an FPC, and a second electronic component such as an FPC, a glass substrate, a plastic substrate, a rigid substrate, or a ceramic substrate. In particular, as the plastic substrate, one in which terminals are formed on a PET substrate that is easily deformed or cracked by pressure bonding is exemplified. In addition, this PET base material may laminate|stack a polyimide base material through an adhesive agent. Their total thickness can be, for example, 0.15 mm or less. IC chips or wafers may be stacked and multilayered using the anisotropic conductive film of the present invention. In addition, the electronic component connected by the anisotropic conductive film of this invention is not limited to the electronic component mentioned above. In recent years, it can be used for various electronic parts that are diversifying. The present invention also includes a connection structure in which electronic components are anisotropically conductively connected to each other using the anisotropic conductive film of the present invention. Moreover, the manufacturing method of the connection structure which has the process of anisotropically conductively connecting a 1st electronic component and a 2nd electronic component by arrange|positioning the anisotropic conductive film of this invention therebetween is also included.

As a method for connecting electronic components using an anisotropic conductive film, when the resin layer of the anisotropic conductive film is composed of a single layer of the conductive particle-dispersed layer 3, conductive particles of the anisotropic conductive film are used for second electronic components such as various substrates. (1A, 1B) is temporarily bonded and temporarily bonded from the side where the conductive particles (1A, 1B) are embedded in the surface, and a first electronic component such as an IC chip is attached to the side where the conductive particles (1A, 1B) of the temporarily bonded anisotropic conductive film are not embedded in the surface. It can be manufactured by combining and heat-pressing. When the insulating resin layer of the anisotropic conductive film contains not only a thermal polymerization initiator and a thermally polymerizable compound, but also a photopolymerization initiator and a photopolymerizable compound (which may be the same as the thermally polymerizable compound), compression using light and heat together It may be a method. In this way, unwanted movement of the conductive particles can be suppressed to a minimum. Alternatively, the side on which the conductive particles are not embedded may be temporarily attached to the second electronic component for use. Further, the anisotropic conductive film may be temporarily attached to the first electronic component instead of the second electronic component.

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

Example

Hereinafter, the present invention will be specifically described based on examples.

Examples 1 to 4, Comparative Examples 1 and 2

(1) Manufacture of anisotropic conductive film

With the formulations shown in Table 1, a resin composition for forming an insulating resin layer for forming a conductive particle dispersion layer and a resin composition for forming a second insulating resin layer were prepared, respectively. The lowest melt viscosity of the insulating resin layer was 3000 Pa·s or more, and the ratio between the lowest melt viscosity of this insulating resin layer and the lowest melt viscosity of the second insulating resin layer was 2 or more.

On the other hand, high-hardness conductive particles having about 70 alumina particles (average particle size: 150 nm) on the surface of the resin core particles and a Ni layer (thickness: 100 nm) on the outermost layer (20% compressive modulus: 22000 N/mm, average particle size 3 µm, manufactured by Sekisui Chemical Industry Co., Ltd. (manufactured by the method described in Japanese Unexamined Patent Publication No. 2006-269296) was prepared, and low-hardness conductive particles having the same structure as the high-hardness conductive particles (20% Compressive elastic modulus of 6000 N/mm 2 , average particle diameter of 3 μm, Sekisui Chemical Industry Co., Ltd. product) was prepared. In Examples 1 to 24 and Comparative Examples 1 to 10, conductive particles similarly manufactured by Sekisui Chemical Industry Co., Ltd. were prepared.

High-hardness conductive particles and low-hardness conductive particles were mixed with a resin composition for forming an insulating resin layer (high-viscosity resin layer) so that their number densities reached the ratios shown in Table 2, and they were mixed with a bar coater on a PET film having a film thickness of 50 μm. and dried in an oven at 80°C for 5 minutes to form a conductive particle dispersion layer in which high-hardness conductive particles and low-hardness conductive particles were randomly dispersed on the PET film. The thickness of the insulating resin layer of this conductive particle-dispersed layer was 6 µm. In addition, the resin composition for forming the second insulating resin layer is coated on a PET film having a film thickness of 50 μm with a bar coater and dried in an oven at 80° C. for 5 minutes, thereby forming a second insulating resin layer having a thickness of 12 μm on the PET film A resin layer was formed. This resin layer was laminated on the conductive particle dispersion layer described above to obtain an anisotropic conductive film.

(2) Evaluation of anisotropic conductive film

Using the anisotropic conductive films of Examples and Comparative Examples prepared in (1) cut to an area sufficient for connection, a connection structure of an electronic component was prepared, (a) capture efficiency, (b) indentation, (c) particle size The break rate and (d) resistance value were evaluated as follows. A result is shown in Table 2.

(a) capture efficiency

The evaluation IC shown below and the glass substrate (Ti/Al wiring) to which the evaluation IC and terminal patterns correspond were heated and pressed for 5 seconds at 200°C with the pressing force shown in Table 2 through an anisotropic conductive film, and evaluated. A connection structure was obtained.

IC for evaluation:

Dimensions 1.8 × 20.0 mm

thickness 0.5 mm

Bump specification size 30 × 85 ㎛, distance between bumps 20 ㎛, bump surface material Au

The number of captured high-hardness conductive particles and low-hardness conductive particles was measured for 100 terminal pairs after heating and pressing, and the average was obtained. In addition, the theoretical values of high-hardness conductive particles and low-hardness conductive particles present on the terminal before heating and pressurization are calculated from [terminal area for 100 terminals] x [number density of conductive particles], and the measured The ratio of the number of catches to the theoretical value was obtained and evaluated according to the following criteria. For practical purposes, B evaluation or higher is preferable.

Capture Efficiency Evaluation Criteria

A: 30% or more

B: 15% or more and less than 30%

C: less than 15%

(b) indentation

Indentations of the high-hardness conductive particles and the low-hardness conductive particles in the bonded structure for evaluation produced in (a) were observed with a metal microscope, and the high-hardness conductive particles and the low-hardness conductive particles were observed for the five terminal pairs after heating and pressing. The number of indentations (captures) was measured using image analysis software WinROOF (Mitani Corporation), and the average was obtained. In addition, the theoretical values of high-hardness conductive particles and low-hardness conductive particles present on the terminal before heating and pressurization are calculated from [terminal area for 5 terminals] x [number density of conductive particles], and the measured The ratio of the number of indentations (captures) to the theoretical value was determined and evaluated according to the following criteria. In addition, the confirmed indentation is about 100 indentations in the dispersion type anisotropic conductive film in which the conductive particles are randomly arranged, and the total number of indents of 5 bumps is about 100, and the conductive particles described later are arranged in a square lattice. In the film, the total number of indentations of 5 bumps was about 200.

Indentation Evaluation Criteria

OK: When 50% or more of the theoretical value is recognized as an indentation

NG: When less than 50% of the theoretical value is recognized as an indentation

(c) Particle collapse rate

Immediately after production of the bonded structure for evaluation produced in (a) (initial stage), and the bonded structure for evaluation produced in (a) placed in a constant temperature chamber at a temperature of 85 ° C. and a humidity of 85% RH for 500 hours (500 h) For each of , the distance between the terminals facing each other was measured as the particle diameter after crimping, and the average particle diameter was obtained. On the other hand, the average particle diameter before crimping was also obtained, the particle collapse rate was calculated by the following formula, and evaluated according to the following criteria. For practical purposes, B evaluation or higher is preferable.

Particle collapse rate (%)

= ([Average particle diameter before compression] - [Average particle diameter after compression]) × 100/[Average particle diameter before compression]

Criteria for evaluation of particle collapse rate at the initial stage and at 500 h

A: 10% or more

B: 5% or more and less than 10%

C: less than 5%

(d) resistance value

Immediately after production of the bonded structure for evaluation produced in (a) (initial stage), and the bonded structure for evaluation produced in (a) placed in a constant temperature chamber at a temperature of 85 ° C. and a humidity of 85% RH for 500 hours (500 h) For each of , the conduction resistance was measured by the 4-terminal method and evaluated according to the following criteria. The resistance value is preferably equal to or higher than B evaluation for practical use.

Resistance value evaluation criteria in the initial stage

A: Less than 3 Ω

B: 3 Ω or more and less than 5 Ω

C: 5 Ω or more and less than 10 Ω

D: 10 Ω or more

Resistance value evaluation criteria at 500 h

A: Less than 3 Ω

B: 3 Ω or more and less than 5 Ω

C: 5 Ω or more and less than 10 Ω

D: 10 Ω or more

Examples 5 to 8, Comparative Examples 3 and 4

The same conductive particles as in Example 1 were prepared. However, by adjusting the 20% compressive modulus of the resin core particles, conductive particles having a 20% compressive modulus of 14000 N/mm2 (average particle diameter: 3 μm) as high-hardness conductive particles and 20% compressive-elastic modulus as low-hardness conductive particles Conductive particles (average particle diameter of 3 μm) having this 6000 N/mm 2 were prepared.

High-hardness conductive particles and low-hardness conductive particles were carried out in the same manner as in Example 1 except that the high-hardness conductive particles and low-hardness conductive particles were mixed with the resin composition for forming an insulating resin layer (high-viscosity resin layer) so as to have the ratios shown in Table 3. An anisotropic conductive film in which particles are randomly dispersed was prepared.

Further, in the same manner as in Example 1, (a) capture efficiency, (b) indentation, (c) particle collapse rate, and (d) resistance value were evaluated. A result is shown in Table 3.

Examples 9 to 12, Comparative Example 5

The same conductive particles as in Example 1 were prepared. However, by adjusting the 20% compressive modulus of the resin core particles, conductive particles having a 20% compressive modulus of 9000 N/mm2 (average particle diameter: 3 µm) as high-hardness conductive particles and 20% compressive-elastic modulus as low-hardness conductive particles Conductive particles (average particle diameter of 3 μm) having this 6000 N/mm 2 were prepared.

High-hardness conductive particles and low-hardness conductive particles were carried out in the same manner as in Example 1 except that the high-hardness conductive particles and low-hardness conductive particles were mixed with the resin composition for forming an insulating resin layer (high-viscosity resin layer) so as to have the ratios shown in Table 4. An anisotropic conductive film in which particles are randomly dispersed was prepared.

Further, in the same manner as in Example 1, (a) capture efficiency, (b) indentation, (c) particle collapse rate, and (d) resistance value were evaluated. A result is shown in Table 4.

Examples 13 to 16, Comparative Examples 6 and 7

A resin composition for forming an insulating resin layer forming a conductive particle dispersion layer was prepared with the formulations shown in Table 1, and this was coated on a PET film having a film thickness of 50 μm with a bar coater, and dried in an oven at 80° C. for 5 minutes. , an insulating resin layer was formed on the PET film. The thickness of this insulating resin layer was 6 μm. In addition, a resin composition for forming a second insulating resin layer was prepared with the formulation shown in Table 1, and a resin layer having a thickness of 12 μm was formed in the same manner.

Further, the same high-hardness conductive particles having a 20% compressive elastic modulus of 22000 N/mm2 as in Example 1 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm2 were prepared.

On the other hand, a mold was manufactured so that the conductive particles were arranged in a tetragonal lattice arrangement as shown in Fig. 1A, and the total number density of the high-hardness conductive particles and the low-hardness conductive particles became the values shown in Table 5, and this mold had known transparency. By pouring in the resin pellets in a molten state, cooling them and hardening them, a resin mold with an arrangement pattern shown in Fig. 1A was formed.

In the concave portion of the resin mold, high-hardness conductive particles and low-hardness conductive particles were mixed and filled in a ratio shown in Table 5, and the above-described insulating resin layer was covered thereon, and adhered by pressurizing at 60°C and 0.5 MPa. (貼着) made it. Then, the insulating resin layer was peeled off from the mold, and conductive particles on the insulating resin layer were press-fitted into the insulating resin layer under (pressure conditions: 60 to 70°C, 0.5 MPa) to form a conductive particle dispersion layer. In this case, the landfill rate was 99.9%. A resin layer formed from the above-described resin composition for forming a second insulating resin layer is laminated on the surface of the conductive particle dispersion layer in which the conductive particles are embedded, and the high-hardness conductive particles and the low-hardness conductive particles are arranged in a tetragonal lattice as a whole. An anisotropic conductive film was prepared.

The anisotropic conductive film obtained in this way was cut into an area sufficient for connection, and a bonded structure for evaluation was prepared in the same manner as in Example 1 using the cut anisotropic conductive film, (a) capture efficiency, (b) indentation, (c) ) particle collapse rate and (d) resistance value were evaluated. A result is shown in Table 5.

Examples 17 to 20, Comparative Examples 8 and 9

High-hardness conductive particles having a 20% compressive elastic modulus of 14000 N/mm 2 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm 2 were prepared as in Example 5.

The high-hardness conductive particles and the low-hardness conductive particles were mixed in the ratio shown in Table 6 and filled into the resin mold in the same manner as in Example 13. An anisotropic conductive film was prepared.

In addition, in the same way as in Example 1, the anisotropic conductive film was cut to an area sufficient for connection, and (a) trapping efficiency, (b) indentation, (c) particle collapse rate, and (d) resistance value were evaluated using the cut anisotropic conductive film. did A result is shown in Table 6.

Examples 21 to 24, Comparative Example 10

High-hardness conductive particles having a 20% compressive elastic modulus of 9000 N/mm 2 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm 2 were prepared as in Example 9.

The high-hardness conductive particles and the low-hardness conductive particles were mixed in the ratio shown in Table 7 and filled into the resin mold in the same manner as in Example 13, wherein the high-hardness conductive particles and the low-hardness conductive particles were arranged in a square lattice as a whole. An anisotropic conductive film was prepared.

In addition, in the same way as in Example 1, the anisotropic conductive film was cut to an area sufficient for connection, and (a) trapping efficiency, (b) indentation, (c) particle collapse rate, and (d) resistance value were evaluated using the cut anisotropic conductive film. did A result is shown in Table 7.

From Table 2, Example 1 containing both high-hardness conductive particles having a 20% compressive elastic modulus of 22000 N/mm2 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm2, wherein the conductive particles are randomly arranged. According to the anisotropic conductive film of -4, it turns out that evaluation of an indentation was favorable, and conduction characteristics (initial resistance value, 500h resistance value) were also favorable. On the other hand, the anisotropic conductive film of Comparative Example 1 containing only high-hardness conductive particles having a 20% compressive modulus of 22000 N/mm2 was also similar to that of Comparative Example 2 containing only low-hardness conductive particles having a 20% compressive modulus of 6000 N/mm2. The anisotropic conductive film was also inferior in indentation evaluation, and the anisotropic conductive film of Comparative Example 1 containing only high-hardness conductive particles was inferior in conduction characteristics (500 h). From this point of view, when the conductive particles are only low-hardness conductive particles, the indentation becomes difficult to see because the hardness is insufficient, and when the conductive particles are only high-hardness conductive particles, the conductive particles are too hard and the compression of the conductive particles is insufficient. It is inferred that the indentation is not well visible. In the case of only the high-hardness conductive particles, even when the evaluation of the indentation was OK, the indentation was more likely to be observed in the example in which the high-hardness conductive particles and the low-hardness conductive particles were mixed.

From Table 5, examples containing both high-hardness conductive particles having a 20% compressive modulus of 22000 N/mm2 and low-hardness conductive particles having a 20% compressive modulus of 6000 N/mm2, wherein the conductive particles are arranged in a tetragonal lattice It can be seen that also in Nos. 13 to 16, the indentation evaluation was good, and the conduction characteristics (initial resistance value, 500-h resistance value) were also good, as in Examples 1 to 4 described above. In Comparative Examples 6 and 7 containing only either high-hardness conductive particles or low-hardness conductive particles, there was a problem with indentation.

From Table 3, examples containing both high-hardness conductive particles having a 20% compressive elastic modulus of 14000 N/mm2 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm2, and the conductive particles are randomly arranged. It can be seen that all of the anisotropic conductive films of No. 5 to 8 had good indentation evaluation and good conduction characteristics (initial resistance value, 500h resistance value). In particular, the pressure at the time of anisotropic conductive connection may be as low as 60 MPa. On the other hand, the anisotropic conductive film of Comparative Example 3 containing only high-hardness conductive particles having a 20% compressive elastic modulus of 14000 N/mm2 has poor indentation evaluation, and when the pressure at the time of anisotropic conductive connection is 60 MPa, the conduction characteristics (500 h) also fell. In addition, the anisotropic conductive film of Comparative Example 4 containing only low-hardness conductive particles as conductive particles had a problem in indentation.

From Table 6, examples containing both high-hardness conductive particles having a 20% compressive modulus of 14000 N/mm2 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm2, wherein the conductive particles are arranged in a tetragonal lattice In Nos. 17 to 20, as in Examples 5 to 8 described above, indentation evaluation was good, and conduction characteristics (initial resistance value, 500h resistance value) were also good. In Comparative Examples 8 and 9 containing only either high-hardness conductive particles or low-hardness conductive particles, there was a problem with indentation.

Also from Table 4, the anisotropic conductive films of Examples 9 to 12 containing both high-hardness conductive particles having a 20% compressive elastic modulus of 9000 N/mm2 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm2 , it can be seen that the evaluation of the indentation is good, the conduction characteristics (initial resistance value, 500 h resistance value) are also good, and especially the pressure at the time of anisotropic conductive connection is good even at a low pressure of 60 MPa. In addition, the anisotropic conductive film of Comparative Example 5 containing only low-hardness conductive particles as conductive particles had a problem in indentation.

From Table 7, examples containing both high-hardness conductive particles having a 20% compressive modulus of 9000 N/mm2 and low-hardness conductive particles having a 20% compressive elastic modulus of 6000 N/mm2, wherein the conductive particles are arranged in a tetragonal lattice In Nos. 21 to 24, as in Examples 9 to 12 described above, the indentation evaluation was good, the conduction characteristics (initial resistance value, 500 h resistance value) were also good, and especially the pressure at the time of anisotropic conductive connection was It can be seen that even a low pressure of 60 MPa is satisfactory. In addition, the anisotropic conductive film of Comparative Example 10 containing only low-hardness conductive particles as conductive particles had a problem in indentation.

1A high hardness conductive particle
1B Low Hardness Conductive Particles
2 insulating resin layer
2b notch (oblique)
2c notches (undulations)
3 conductive particle dispersion layer
4 2nd insulating resin layer
10A, 10B, 10C, 10D, 10E, 10F, 10G anisotropic conductive film
D Average particle diameter of conductive particles
La Layer thickness of insulating resin layer
Lb Distance between the tangential plane at the center of adjacent conductive particles and the deepest part of the conductive particles
Diameter of exposed (immediately above) portion of conductive particle in Lc slope or undulation
The maximum diameter of the inclination or waviness of the insulating resin layer around or immediately above the Ld conductive particles.
Le maximum depth of inclination in the insulating resin layer around the conductive particles
Maximum depth of undulation in the insulating resin layer immediately above the Lf conductive particles

Claims (14)

An anisotropic conductive film in which high-hardness conductive particles having a 20% compressive elastic modulus of 8000 to 28000 N/mm2 and low-hardness conductive particles having a 20% compressive elastic modulus lower than that of the high-hardness conductive particles are dispersed in an insulating resin layer as conductive particles wherein the number density of all conductive particles is 6000/mm2 or more, and the number density of low-hardness conductive particles is 10% or more of all conductive particles;
High-hardness conductive particles and low-hardness conductive particles are randomly dispersed,
An anisotropic conductive film in which the 20% compressive elastic modulus of the low-hardness conductive particles is 10% or more and 70% or less of the 20% compressive elastic modulus of the high-hardness conductive particles. delete According to claim 1,
An anisotropic conductive film in which the number density of low-hardness conductive particles is 20% or more and 80% or less of the total number of conductive particles. According to claim 1,
An anisotropic conductive film in which the average particle diameter of all the conductive particles is less than 10 µm and the number density of all the conductive particles is 6000/mm2 or more and 42000/mm2 or less. According to claim 1,
An anisotropic conductive film in which the average particle diameter of all the conductive particles is 10 µm or more and the number density of all the conductive particles is 20/mm2 or more and 2000/mm2 or less. According to claim 1,
An anisotropic conductive film in which conductive particles including high-hardness conductive particles and low-hardness conductive particles are regularly arranged when viewed from the plane of the film, and their positions in the thickness direction of the film are uniform. According to claim 6,
An anisotropic conductive film in which the ratio of the number of conductive particles including high-hardness conductive particles and low-hardness conductive particles existing in non-contact with each other is 95% or more. According to claim 1,
An anisotropic conductive film in which high-hardness conductive particles and low-hardness conductive particles are randomly dispersed and regularly arranged. According to claim 1,
An anisotropic conductive film in which the surface of the insulating resin layer around the high-hardness conductive particles and the low-hardness conductive particles has an inclination or undulation with respect to a tangential plane of the insulating resin layer at the center between adjacent conductive particles. According to claim 9,
In the inclination, the surface of the insulating resin layer around the high-hardness conductive particles and the low-hardness conductive particles is missing with respect to the tangential plane, and in the undulations, the insulating resin layer directly above the high-hardness conductive particles and the low-hardness conductive particles is missing. An anisotropic conductive film in which the amount of resin in the paper layer is smaller than when it is assumed that the surface of the insulating resin layer immediately above the high-hardness conductive particles and the low-hardness conductive particles is in a tangential plane. A connection structure in which a first electronic component and a second electronic component are anisotropically conductively connected with the anisotropic conductive film according to any one of claims 1 and 3 to 10. According to claim 11,
1st electronic component WHEREIN: A connection structure in which terminals are formed in the PET base material. A method for producing a bonded structure including a step of anisotropically conductively connecting a first electronic component and a second electronic component via the anisotropic conductive film according to any one of claims 1 and 3 to 10. According to claim 13,
The manufacturing method of the connection structure in which the terminal is formed in the PET base material in 1st electronic component.

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