JP7248923B2 - anisotropic conductive film - Google Patents

Description

The present invention relates to an anisotropic conductive film.

Anisotropic conductive films are widely used for mounting electronic components such as IC chips. From the viewpoint of adapting the anisotropic conductive film to a high mounting density, conductive particles are dispersed in the insulating resin layer of the anisotropic conductive film at a high density. However, increasing the density of the conductive particles causes short circuits.

On the other hand, it has been proposed to use conductive particles with insulating particles, in which insulating particles are attached to the surfaces of conductive particles, instead of conventional conductive particles (Patent Document 1). An anisotropic conductive film can be obtained by kneading the conductive particles with insulating particles with a binder resin using a mixer to form a film.

JP 2014-132567 A

However, when the conductive particles with insulating particles are kneaded using a binder resin and a mixer as described in Patent Document 1, the insulating particles are isolated from the conductive particles, and the original insulating properties of the conductive particles with insulating particles are obtained. may not be available. Therefore, there is a possibility that a short circuit may occur in a connected structure of an electronic component anisotropically conductively connected using an anisotropic conductive film in which conductive particles with insulating particles are dispersed in a binder resin at a high density.

In addition, in the anisotropic conductive connection using this anisotropic conductive film, when the conductive particles with insulating particles are pressed against the terminals of the electronic component, not only the conductive particles but also the insulating particles are pressed against the terminals. , there is also the problem that the conduction resistance of the connection structure tends to increase.

On the other hand, the present invention is an anisotropic conductive film using conductive particles with insulating particles, which reduces the conduction resistance of the connection structure anisotropically conductively connected and reliably suppresses the occurrence of short circuits. An object of the present invention is to provide an anisotropic conductive film capable of

In producing an anisotropic conductive film using conductive particles with insulating particles in which the insulating particles are substantially evenly attached to the entire surface of the conductive particles, the present inventors found that the film surface of the conductive particles in the conductive particles with insulating particles Insulating particles adhering in the direction are maintained, but if the number of conductive particles adhering in the film thickness direction of the conductive particles is reduced, in an anisotropic conductive connection using an anisotropic conductive film, Since the conductive particles can be easily pressed directly against the terminal surface without passing through the insulating particles, the conduction resistance of the connection structure can be reduced, and the presence of the insulating particles makes it difficult for short circuits to occur between adjacent terminals. The present invention was conceived.

That is, the present invention provides an anisotropic conductive film in which conductive particles with insulating particles having insulating particles attached to the surface of the conductive particles are dispersed in an insulating resin layer, wherein the conductive particles with insulating particles are electrically conductive Provided is an anisotropic conductive film in which the number of insulating particles in contact with particles in the film thickness direction is less than the number of insulating particles in contact with conductive particles in the film surface direction.
Moreover, this invention provides the manufacturing method of the connection structure which anisotropically conductively connects electronic components using the above-mentioned anisotropic conductive film, and the connection structure obtained by it.

According to the anisotropic conductive film of the present invention, the insulating particles in contact with the conductive particles in the film thickness direction are different from the original conductive particles with insulating particles in which the insulating particles are evenly attached to the entire surface of the conductive particles. The number of particles is less than the number of insulating particles in contact with the conductive particles in the film plane direction. Therefore, when the terminals of an electronic component are anisotropically conductively connected using this anisotropic conductive film, the direct contact between the terminals and the conductive particles is greater than in the case where the initial state of the conductive particles with insulating particles is maintained. Since the contact area is increased, it is possible to reduce the conduction resistance in the connection structure. In addition, according to this anisotropic conductive film, the number of insulating particles in contact with the conductive particles in the film plane direction is maintained in the initial state of the conductive particles with insulating particles, so that in the connection structure, the adjacent terminals It is possible to suppress the short between

FIG. 1A is a plan view showing the arrangement of conductive particles in an anisotropic conductive film 10A of Example. FIG. 1B is a cross-sectional view of an anisotropic conductive film 10A of Example. FIG. 2 is an explanatory diagram of a method for measuring the number of insulating particles that are in contact with the surface of the conductive particles in the film thickness direction or the film surface direction. FIG. 3A is an explanatory diagram of a dent in an insulating resin layer around conductive particles with insulating particles. FIG. 3B is an explanatory view of the recesses of the insulating resin layer on the conductive particles with insulating particles. FIG. 4A is a cross-sectional view illustrating a method for manufacturing an anisotropic conductive film 10A of Example. FIG. 4B is a cross-sectional view illustrating the method of manufacturing the anisotropic conductive film 10A of the example. FIG. 4C is a cross-sectional view illustrating the method for manufacturing the anisotropic conductive film 10A of the example. FIG. 4D is a cross-sectional view illustrating the method of manufacturing the anisotropic conductive film 10A of the example. FIG. 4E is a cross-sectional view illustrating the method of manufacturing the anisotropic conductive film 10A of the example. FIG. 4F is a cross-sectional view illustrating the method of manufacturing the anisotropic conductive film 10A of the example. FIG. 5 is a cross-sectional view of an anisotropic conductive film 10B of an example. FIG. 6 is a cross-sectional view of an anisotropic conductive film 10C of Example. FIG. 7 is a cross-sectional view of an anisotropic conductive film 10D of Example.

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

<Overall structure of anisotropic conductive film>
FIG. 1A is a plan view for explaining the particle arrangement of an anisotropic conductive film 10A of one example of the present invention, and FIG. 1B is its XX sectional view.

This anisotropic conductive film 10A has a structure in which conductive particles 3 with insulating particles, in which insulating particles 2 are in contact with or attached to the surfaces of conductive particles 1, are embedded in one side of an insulating resin layer 5. there is In a plan view of the film, the conductive particles 3 with insulating particles are dispersed without contacting each other, and the conductive particles 3 with insulating particles are dispersed without overlapping each other in the thickness direction of the film. In addition, the positions of the conductive particles 3 with insulating particles in the film thickness direction (longitudinal direction of the paper surface of FIG. 1B) are aligned, and the conductive particles 3 with insulating particles are monolayered in the film surface direction (horizontal direction of the paper surface of FIG. 1B). is making

In the anisotropic conductive film 10A of the present invention, the arrangement of the insulating particles 2 in the insulating particle-attached conductive particles 3 is characteristic, and as described in detail below, the anisotropic conductive film 10A is in contact with the conductive particles 1 in the film thickness direction. The number of insulating particles 2 is smaller than the number of insulating particles 2 in contact with conductive particles 1 in the film surface direction.

<Conductive particles with insulating particles>
In the anisotropic conductive film 10A of the present invention, the number of the insulating particles 2 in the insulating particle-attached conductive particles 3 in the film thickness direction of the conductive particles 1 is smaller than the number of conductive particles in the film surface direction. However, as the conductive particles 3 with insulating particles used as a raw material for producing the anisotropic conductive film 10A of the present invention, it is possible to use conductive particles 1 in which the insulating particles 2 are substantially evenly attached to the entire surface. can.

As such conductive particles with insulating particles, those described in JP-A-2009-280790, JP-A-2014-132567, etc. can be used.

The particle diameter of the conductive particles 1 is preferably 1 μm or more and 30 μm or less, more preferably 2.5 μm or more and 13 μm, from the viewpoint of suppressing an increase in conduction resistance when there is a variation in wiring height and suppressing the occurrence of a short circuit. Below, it is more preferably 3 μm or more and 10 μm or less.

The particle diameter of the insulating particles 2 is smaller than that of the conductive particles 1 . The specific particle size of the insulating particles 2 can be determined according to the particle size of the conductive particles 1, the application of the anisotropic conductive film, etc., but is usually preferably 0.005 μm or more and 5 μm or less, and 0.01 μm. It is more preferably 2.5 μm or less, more preferably 1 μm or less, particularly 0.5 μm or less. This eliminates the need to excessively raise the pressure and temperature required for anisotropic conductive connection. As an example, if the particle diameter of the insulating particles is too small with respect to the particle diameter of the conductive particles, it becomes difficult to impart insulation, so the lower limit is preferably 0.4% or more, and 0.6%. 0.8% or more is more preferable. If the upper limit is too high, there is a risk of adhesion to the conductive particles or a shortage of the required number, so it is preferably 18% or less, more preferably 12% or less, and even more preferably 6% or less.

The particle diameters of the conductive particles 1, the insulating particles 2, and the conductive particles 3 with insulating particles are measured by scattering these particles on glass and using an optical microscope, a metallurgical microscope, a transmission electron microscope (TEM), or a scanning electron microscope. It can be obtained by observing with (SEM) or the like. The particle size in these films can also be obtained from observation with a scanning electron microscope or the like. In the measurement of particle diameter, it is desirable to set the number of samples to be measured to 300 or more. A transmission electron microscope can accurately measure the particle size of a relatively small single insulating particle, and a scanning electron microscope is particularly suitable for determining the particle size of the conductive particles 3 with insulating particles.

The average particle size of the single conductive particles can also be measured by a general particle size distribution analyzer. It may be image type or laser type. As an example of the image-type measuring device, a wet flow type particle size/shape analyzer FPIA-3000 (Malvern) can be mentioned. The number of samples (the number of conductive particles) for measuring the diameter D of conductive particles with insulating particles is preferably 1000 or more. The diameter D of the conductive particles with insulating particles in the anisotropic conductive film can be determined by observation with an electron microscope such as SEM. In this case, the number of samples (the number of conductive particles) for measuring the diameter D of conductive particles with insulating particles is preferably 300 or more.

In the conductive particles 3 with insulating particles used as the raw material for producing the anisotropic conductive film 10A, the ratio (coverage) of the entire surface of the conductive particles 1 covered with the insulating particles 2 is preferably 20 to 97%, and 40 ~95% is more preferred. If the coverage is too small, a short circuit is likely to occur.

The coverage rate is the ratio of the area covered by the insulating particles (projected area) to the entire surface of the conductive particles with insulating particles. As a specific method of obtaining this, 100 conductive particles 3 with insulating particles are observed using a scanning electron microscope, and the coverage in each observed image is averaged. As a simple method for obtaining the coverage, the number of insulating particles per insulating particle-containing conductive particle is measured in each observation image, and the numerical value, the projected area of one insulating particle-containing conductive particle and one insulating particle. The coverage may be calculated from the projected area of . Here, when the observed image of the insulating particles partially overlaps the circular observed image of the conductive particles, the number of the partially overlapped insulating particles may be calculated as 0.5.

On the other hand, in the conductive particles 3 with insulating particles that actually constitute the anisotropic conductive film 10A, the number of the insulating particles 2 in contact with the conductive particles 1 in the film thickness direction is the number of the insulating particles 2 in contact with the conductive particles 1 in the film plane direction. less than the number Here, the number of insulating particles 2 in contact with the conductive particles 1 in the film thickness direction means that in the cross section of the insulating particle-containing conductive particles 3 in the anisotropic conductive film 10A shown in FIG. When the particles 3 are divided into four regions A1, A2, A3, and A4 by a straight line inclined by +45° and a straight line inclined by −45° with respect to the film thickness direction passing through the center of the conductive particles 1, the conductive particles It refers to the number of insulating particles 2 present in areas A1 and A2 above and below 1 (areas along the film surface). In addition, the number of insulating particles 2 in contact with the conductive particles 1 in the film surface direction is the area on the left and right of the conductive particles 1 among the above-mentioned four areas A1, A2, A3, and A4 (areas along the film thickness direction) It refers to the number of insulating particles 2 present in A3 and A4. Therefore, if the numbers of insulating particles 2 existing in the regions A1, A2, A3, and A4 are N _A1 , N _A2 , N _A3 , and N _A4 , in the present invention, (N _A3 +N _A4 )>(N _A1 +N _A2 ). In addition, it is preferable that the cross section in the film thickness direction has a plurality of different directions in the same film (check cross-sectional views in different directions), and it is more preferable that two cross sections at 90 ° are included. .

In determining the number of insulating particles 2 present in the areas A1, A2, A3, and A4, the insulating particles 2 straddling both the upper and lower areas A1 and A2 and the left and right areas A3 and A4 of the conductive particles 1 are Attribution is determined by which region it belongs to.

Moreover, in the present invention, it is not necessary for all the conductive particles 3 with insulating particles to satisfy the above inequality. The number of the insulating particles 2 present in the regions A1, A2, A3, and A4 of the individual conductive particles 3 with insulating particles may vary. However, when all the conductive particles 3 with insulating particles contained in the anisotropic conductive film are averaged, the above inequality holds, and N _A3 and N _A4 are greater than N _A1 and N _A2 .

In addition, it is not realistic to confirm that the above-described inequality holds for all the conductive particles 3 with insulating particles contained in the anisotropic conductive film. Therefore, as shown below, when the number of insulating particles 2 present in the regions A1, A2, A3, and A4 is measured and the above inequality is satisfied, the above inequality for the average of all the conductive particles with insulating particles It can be considered that the relationship of

That is, for each conductive particle 3 with insulating particles, the number of insulating particles 2 present in the regions A1, A2, A3, and A4 can be determined by observing the cross section of the anisotropic conductive film 10A using a scanning electron microscope. When measuring, a plurality of rectangular measurement areas with a side of 100 μm or more are set apart from each other (preferably 5 or more, more preferably 10 or more), and the total area is set to 1 mm ^{2 or} more, From each measurement area 100 extracted conductive particles 3 with insulating particles were observed, and the number of insulating particles 2 present in regions A1 and A2 and the number of insulating particles 2 present in regions A3 and A4 for each conductive particle 3 with insulating particles. , and as an average of 100 conductive particles with insulating particles, the number of insulating particles 2 in contact with the conductive particles 1 in the film thickness direction (N _A1 + N _A2 ), and the number of insulating particles 2 in contact with the conductive particles 1 in the film plane direction. The number (N _A3 +N _A4 ) is obtained, and whether or not the above inequality holds is checked. The measurement area may be appropriately adjusted according to the size of the conductive particles.

In addition, it is convenient that the number of insulating particles 2 in contact with the conductive particles 1 in the film thickness direction (N _A1 +N _A2 ) is less than the number of insulating particles 2 in contact with the conductive particles 1 in the film plane direction (N _A3 +N _A4 ). As a method for checking, in a measurement area having an area of 1 mm ² or more, the number of insulating particles 2 overlapping the conductive particles 1 in plan view of either the front or back surface of the anisotropic conductive film is It may be confirmed that the number of the insulating particles 2 overlapping the conductive particles 1 in plan view of the other film surface is smaller than the number of the insulating particles 2 overlapping the conductive particles 1 . As will be described later, when the conductive particles with insulating particles are pressed into the insulating resin layer in the manufacturing process of the anisotropic conductive film of the present invention, N _A3 , N _A4 ≥ N _A2 > N _A1
Therefore, by confirming N _A2 >N _A1 , the number of insulating particles 2 in contact with the conductive particles 1 in the film thickness direction (N _A1 +N _A2 ) is the number of insulating particles 2 in contact with the conductive particles 1 in the film plane direction. It can be confirmed that the number is less than the number (NA3+NA4).

The difference in the number of the insulating particles 2 due to the regions A1, A2, A3, and A4 is determined by arranging the conductive particles 3 with insulating particles in a predetermined array in the method of manufacturing the anisotropic conductive film 10A, as will be described later. It occurs when using a transcription type for That is, when the conductive particles 3 with insulating particles are transferred from the transfer mold to the insulating resin layer, the insulating particles 2 (the insulating particles 2 in the region A1) in contact with the conductive particles 1 in the film thickness direction are displaced by friction with the transfer mold. Alternatively, due to friction with the pressing member, it is easy to detach from the conductive particles 1 and remain in the transfer mold, and the insulating particles 2 that are in contact with the conductive particles 1 in the film thickness direction are in contact with the conductive particles 1 in the film surface direction. Although it may move, the insulating particles 2 that are in contact with the conductive particles 1 in the film surface direction do not separate from the conductive particles 1 or move even if the conductive particles 3 with insulating particles are transferred from the transfer mold to the insulating resin layer. occurs because it is difficult to occur.

<Dispersed State of Conductive Particles with Insulating Particles>
In the present invention, the dispersed state of the conductive particles with insulating particles includes a state in which the conductive particles with insulating particles 3 are randomly dispersed and a state in which the conductive particles with insulating particles 3 are dispersed in a regular arrangement. In this dispersed state, the conductive particles with insulating particles are preferably arranged without contact with each other, and the number ratio thereof is preferably 95% or more, more preferably 98% or more, and still more preferably 99.5% or more. . With respect to this number ratio, the conductive particles with insulating particles intentionally brought into contact with each other in a regular arrangement in the dispersed state are counted as one. It can be obtained with N=200 or more in the same manner as the method of obtaining the occupied area ratio of the conductive particles with insulating particles in the film plan view described later. In either case, it is preferable from the viewpoint of capture stability that the positions in the film thickness direction are uniform. Here, the position of the conductive particles 1 in the film thickness direction is not limited to being aligned at a single depth in the film thickness direction, and the front and back interfaces of the insulating resin layer 5 or the vicinity thereof includes an embodiment in which conductive particles are present in each of

In the present invention, as described above, it is preferable that the conductive particles 3 with insulating particles are regularly arranged in a plan view of the film. For example, as shown in FIG. . In addition, as a regular arrangement mode of the conductive particles with insulating particles, a lattice arrangement such as a rectangular lattice, an orthorhombic lattice, and a hexagonal lattice can be mentioned. The regular arrangement is not limited to a lattice arrangement, and for example, particle rows in which conductive particles with insulating particles are arranged linearly at predetermined intervals may be arranged side by side at predetermined intervals. By arranging the conductive particles 3 with insulating particles in a non-contact manner with each other and arranging them in a regular arrangement such as a lattice, pressure is applied evenly to each conductive particle 3 with insulating particles at the time of anisotropic conductive connection, and the conduction resistance is reduced. Variation can be reduced. A regular arrangement can be confirmed, for example, by repeating a predetermined particle arrangement in the longitudinal direction of the film.

The lattice axis or arrangement axis of the arrangement of the conductive particles with insulating particles may be parallel to the longitudinal direction of the anisotropic conductive film, or may intersect the longitudinal direction of the anisotropic conductive film. It can be determined according to the terminal pitch or the like. For example, when making an anisotropic conductive film for fine pitch, the lattice axis A of the conductive particles 3 with insulating particles is oblique to the longitudinal direction of the anisotropic conductive film 10A as shown in FIG. 1A, The angle θ formed between the longitudinal direction of the terminals 20 connected by the anisotropic conductive film 10A (the lateral direction of the film) and the lattice axis A is preferably 6° to 84°, preferably 11° to 74°.

The inter-particle distance of the conductive particles 3 with insulating particles is appropriately determined according to the size and terminal pitch of the terminals to be connected by the anisotropic conductive film. For example, when the anisotropic conductive film is adapted to fine-pitch COG (Chip On Glass), the distance between the conductive particles 1 of the closest conductive particles 3 with insulating particles is set to the distance between the conductive particles 1 with insulating particles from the viewpoint of preventing the occurrence of short circuits. It is preferably larger than 0.5 times the particle diameter, more preferably larger than 0.7 times. On the other hand, from the viewpoint of capturing the insulating particle-containing conductive particles 3, the distance between the conductive particles 1 of the closest insulating particle-containing conductive particles 3 is preferably 4 times or less the insulating particle-containing conductive particle diameter, and 3 times or less. is more preferable.

Also, the area occupation ratio of the conductive particles with insulating particles is determined to be 35% or less, preferably 0.3 to 30%. Here, the area occupation ratio is
[Number density of conductive particles with insulating particles in plan view] x [Average area of one conductive particle with insulating particles] x 100
Calculated by

In the formula, the area for measuring the number density of the conductive particles with insulating particles is an arbitrary plurality of rectangular areas (preferably 5 or more, more preferably 10 or more) each side of which is 100 μm or more in the anisotropic conductive film 10A. It is preferable to set the total area of the measurement regions to 2 mm 2 or more. The size and number of individual regions may be appropriately adjusted according to the state of the number density. As an example of a case where the number density is relatively high for fine-pitch applications, 200 locations (2 mm ² ) in a region with an area of 100 μm×100 μm arbitrarily selected from the anisotropic conductive film 10A are observed using a metallographic microscope or the like. By measuring the number density and averaging it, it is possible to obtain the "number density of the conductive particles with insulating particles in plan view" in the above formula. A region with an area of 100 μm×100 μm is a region in which one or more bumps exist in a connection object with an inter-bump space of 50 μm or less.

The number density is preferably 150 to 70,000/mm ² , particularly for fine pitch applications, preferably 6,000 to 42,000/mm ² , more preferably 10,000 to 40,000/mm ² , still more preferably 15,000 to 15,000. 35000/mm ² . In addition, less than 150/mm ² is not excluded.

The number density of the conductive particles with insulating particles is obtained using a metallurgical microscope as described above, and is also measured using image analysis software (e.g., WinROOF, Mitani Shoji Co., Ltd.) for the microscope image of the conductive particles with insulating particles. You may

The average planar view area of the film per insulating particle-attached conductive particle can be obtained by measurement from an image of the film surface observed by a metallurgical microscope or the like. Image analysis software may be used as described above. It is preferable that N=300 or more.

The area occupancy of the conductive particles with insulating particles in the film plan view is an index of the thrust force required for the pressing jig for thermocompression bonding the anisotropic conductive film to the electronic component. Conventionally, in order to adapt an anisotropic conductive film to a fine pitch, the distance between conductive particles has been narrowed and the number density has been increased as long as short circuits do not occur. A problem arises in that the thrust force required for the pressing jig to thermally press-bond the anisotropic conductive film to the electronic component becomes excessively large, and the conventional pressing jig does not provide sufficient pressing force. On the other hand, by setting the area occupancy within the above range, the thrust required for the pressing jig for thermocompression bonding the anisotropic conductive film to the electronic component can be kept low.

<Insulating resin layer>
(Minimum melt viscosity of insulating resin layer)
In the anisotropic conductive film of the present invention, the minimum melt viscosity of the insulating resin layer 5 is not particularly limited, and is appropriately determined according to the use object of the anisotropic conductive film, the manufacturing method of the anisotropic conductive film, etc. be able to. For example, as long as depressions 5b (FIG. 3A) and 5c (FIG. 3B), which will be described later, can be formed, it can be about 1000 Pa·s depending on the method of manufacturing the anisotropic conductive film. On the other hand, as a method for producing an anisotropic conductive film, when conducting a method in which the conductive particles with insulating particles are held on the surface of the insulating resin layer in a predetermined arrangement and the conductive particles with insulating particles are pushed into the insulating resin layer, The insulating resin layer preferably has a minimum melt viscosity of 1100 Pa·s or more from the viewpoint that the insulating resin layer can be formed into a film.

Further, as will be described later in the manufacturing method of an anisotropic conductive film, recesses 5b are formed around the exposed portions of the conductive particles 3 with insulating particles pressed into the insulating resin layer 5 as shown in FIG. 3A. , from the point of forming recesses 5c directly above the conductive particles 3 with insulating particles pushed into the insulating resin layer 5 as shown in FIG. It is preferably 3,000 to 15,000 Pa·s, and more preferably 3,000 to 10,000 Pa·s. This minimum melt viscosity can be obtained by using a rotary rheometer (manufactured by TA Instruments) as an example, holding a measuring pressure of 5 g constant, and using a measuring plate with a diameter of 8 mm. More specifically, the temperature range At 30 to 200° C., it can be obtained by setting the temperature increase rate to 10° C./min, the measurement frequency to 10 Hz, and the load variation to the measurement plate to 5 g.

By setting the minimum melt viscosity of the insulating resin layer 5 to a high viscosity of 1500 Pa s or more, it is possible to suppress unnecessary movement of the filler when the anisotropic conductive film is crimped to the article, especially at the time of anisotropic conductive connection. It is possible to prevent the conductive particles to be sandwiched between the terminals from flowing away due to the resin flow.

Further, when the conductive particles 3 with insulating particles are pushed into the insulating resin layer 5, the conductive particles 3 with insulating particles are exposed from the insulating resin layer 5 when the conductive particles 3 with insulating particles are pushed. When the conductive particles 3 with insulating particles are pushed into the insulating resin layer 5 in such a manner that the insulating resin layer 5 is plastically deformed, the insulating resin layer 5 around the conductive particles 3 with insulating particles has a dent 5b (Fig. 3A) is formed, or the conductive particles with insulating particles 3 are embedded in the insulating resin layer 5 without being exposed from the insulating resin layer 5. A viscous body having such a high viscosity as to form a dent 5c (FIG. 3B) on the surface of the insulating resin layer 5 directly above the conductive particles 3 with the insulating particles when the particles 3 are pushed. Therefore, the lower limit of the viscosity of the insulating resin layer 5 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, 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. This measurement is performed in the same manner as for the minimum melt viscosity, and can be obtained by extracting the value at a temperature of 60°C.

The specific viscosity of the insulating resin layer 5 when the conductive particles 3 with insulating particles are pushed into the insulating resin layer 5 depends on the shape and depth of the recesses 5b and 5c to be formed, and the lower limit is preferably 3000 Pa. ·s or more, more preferably 4000 Pa·s or more, still more preferably 4500 Pa·s or more, and the upper limit is preferably 20000 Pa·s or less, more preferably 15000 Pa·s or less, still more preferably 10000 Pa·s or less. Also, such a viscosity is preferably obtained at 40-80°C, more preferably 50-60°C.

As described above, since the recesses 5b (FIG. 3A) are formed around the conductive particles 3 with insulating particles exposed from the insulating resin layer 5, the anisotropic conductive film is crimped to the article. The resistance received from the insulating resin against the flattening of the conductive particles 3 with insulating particles is reduced as compared with the case without the recesses 5b. Therefore, the conductive particles are easily sandwiched between the terminals at the time of anisotropic conductive connection, thereby improving the conduction performance and improving the trapping property.

In addition, since the recesses 5c (FIG. 3B) are formed on the surface of the insulating resin layer 5 directly above the conductive particles 3 with insulating particles that are buried without being exposed from the insulating resin layer 5, there are no recesses 5c. Compared to the case, the pressure when the anisotropic conductive film is pressure-bonded to the article tends to be concentrated on the conductive particles 3 with insulating particles. Therefore, the conductive particles are easily sandwiched between the terminals at the time of anisotropic conductive connection, thereby improving capture properties and conductive performance.

In the method for manufacturing an anisotropic conductive film, which will be described later, the embedding ratio when the conductive particles 3 with insulating particles are pushed into the insulating resin layer 5 is set to 100% or less, and the conductive particles 3 with insulating particles are in the insulating resin layer. 5, if the viscosity of the insulating resin layer 5 at 60° C. is within the above range, the insulating resin layer 5 after the conductive particles 3 with insulating particles are pushed into the conductive particles with insulating particles. A depression 5b (FIG. 3A) may be formed around the particle 3 . At this time, only the insulating particles may be exposed. Further, when the embedding rate is set to more than 100% and the conductive particles 3 with insulating particles are not exposed from the insulating resin layer 5 and are embedded in the insulating resin layer 5, the conductive particles 3 with insulating particles A recess 5c (FIG. 3B) may be formed on the surface of the insulating resin layer 5 of . The meaning of the embedding rate will be described in detail in the description of the embedding state of the conductive particles with insulating particles later.

Such depressions 5b and 5c are formed according to the viscosity, pushing speed, temperature, etc. of the insulating resin layer 5 when the conductive particles 3 with insulating particles are pushed into the insulating resin layer 5. As shown in FIG. The presence or absence of the recesses 5b and 5c does not particularly affect the effects of the present invention, but the depth of the recesses 5b and 5c is large (for example, the depth of the deepest part of the recess is 10 times the diameter D of the conductive particles with insulating particles). % or more) are locally concentrated, and if such an area is laminated facing the substrate, depending on the material and surface condition of the substrate, floating may occur after the anisotropic conductive connection in that area. may occur, and the appearance may be inferior even if there is no problem in practical use. To deal with this, the surface of the anisotropic conductive film having such a region is heated and pressed to such an extent that the anisotropic conductive connection is not hindered, or resin is sprayed to form the depressions 5b, It is preferable to make 5c shallow or flat. In this case, the sprayed resin preferably has a lower viscosity than the resin forming the insulating resin layer 5 . The concentration of the sprayed resin may be diluted to such an extent that the dents in the insulating resin layer 5 can be confirmed after spraying.

<“Tilted” or “undulating” instead of dents>
The "dents" 5b, 5c of the anisotropic conductive film as shown in Figures 3A, 3B can also be described in terms of "tilts" or "undulations." Description will be made below with reference to the drawings.

The anisotropic conductive film 10A has a conductive particle dispersed layer, that is, a layer in which the conductive particles 3 with insulating particles are regularly dispersed in an exposed state on one side of the insulating resin layer 5 (FIGS. 3A and 3B ). In the plan view of the film, the conductive particles 3 with insulating particles are not in contact with each other, and the conductive particles 3 with insulating particles are regularly dispersed without overlapping each other in the film thickness direction, and the film of the conductive particles 3 with insulating particles It constitutes a single-layer conductive particle layer that is evenly positioned in the thickness direction.

On the surface 5a of the insulating resin layer 5 in the vicinity of each conductive particle 3 with insulating particles, an inclination 5b is formed with respect to the tangential plane 5p of the insulating resin layer 5 in the central portion between the adjacent conductive particles with insulating particles. It is As will be described later, in the anisotropic conductive film of the present invention, even if undulations 5c are formed on the surface of the insulating resin layer 5 directly above the conductive particles 3 with insulating particles embedded in the insulating resin layer 5, Good (Fig. 3B).

In the present invention, the term “inclination” means that the flatness of the surface of the insulating resin layer is impaired in the vicinity of the conductive particles 3 with insulating particles, and a part of the insulating resin layer is missing with respect to the tangential plane 5p. It means that the amount is reduced. In other words, with the inclination, the surface of the insulating resin layer in the vicinity of the conductive particles with insulating particles is chipped with respect to the tangential plane. On the other hand, "undulation" means that the surface of the insulating resin layer directly above the conductive particles with insulating particles has undulations, and the resin is reduced due to the presence of portions with height differences such as undulations. do. In other words, the amount of resin in the insulating resin layer directly above the conductive particles with insulating particles is less than when the surface of the insulating resin layer directly above the conductive particles with insulating particles is on the tangential plane. Therefore, only the insulating particles may be exposed in the undulation. These can be recognized by comparing the portion corresponding to directly above the conductive particles with insulating particles and the flat surface portion between the conductive particles (FIGS. 3A and 3B). In some cases, the undulation starting point exists as an inclination.

As described above, since the inclination 5b (FIG. 3A) is formed around the conductive particles 3 with insulating particles exposed from the insulating resin layer 5, the conductive particles 3 with insulating particles Since the resistance received from the insulating resin against the flattening of the conductive particles 3 with insulating particles that occurs when the is sandwiched between the terminals is reduced compared to the case where there is no inclination 5 b, the conductive particles with insulating particles at the terminals Since it becomes easier to hold the wire, the conduction performance is improved, and the trapping property is improved. This inclination is preferably along the outer shape of the conductive particles with insulating particles. This is because, in addition to the effect of connection becoming more likely to be exhibited, the conductive particles with insulating particles can be easily recognized, which makes it easier to perform inspections and the like in the production of the anisotropic conductive film. Also, the inclination and undulations may partially disappear when the insulating resin layer is heat-pressed, but the present invention encompasses this. In this case, the conductive particles with insulating particles may be exposed at one point on the surface of the insulating resin layer. The anisotropic conductive film is connected to a variety of electronic components, and as long as it is tuned to suit these, it is desirable to have a high degree of freedom in design so that various requirements can be met. It can be used even if it is made to disappear partially.

In addition, undulations 5 c ( FIG. 3B ) are formed on the surface of the insulating resin layer 5 directly above the conductive particles 3 with insulating particles that are buried without being exposed from the insulating resin layer 5 . Similarly, the pressing force from the terminal is more likely to be applied to the conductive particles with insulating particles during anisotropic connection. In addition, since the amount of resin directly above the conductive particles with insulating particles is reduced due to the presence of undulations compared to the case where the resin is deposited flatly, the resin directly above the conductive particles with insulating particles is expelled during connection. Since the contact between the terminal and the conductive particles with insulating particles is facilitated, the ability of the terminals to capture the conductive particles with insulating particles is improved, and the reliability of conduction is improved.

(Position of conductive particles with insulating particles in the thickness direction of the insulating resin layer)
The position of the conductive particles 3 with insulating particles in the thickness direction of the insulating resin layer 5 when considering the viewpoint of "inclination" or "undulation" is the same as described above. 5, or may be embedded in the insulating resin layer 5 without being exposed, but the conductive particles with insulating particles from the tangential plane 5p in the central part between adjacent conductive particles with insulating particles The ratio (Lb/D) (hereinafter referred to as embedding rate) of the distance of the deepest part of the particles (hereinafter referred to as embedding amount) Lb to the diameter D of the conductive particles with insulating particles is 30% or more and 105% or less. is preferable, and 60% or more and 105% or less is more preferable in order to obtain the effects of the invention.

When the embedding ratio (Lb/D) is 30% or more and less than 60%, the proportion of the conductive particles with insulating particles exposed from the relatively high-viscosity resin that holds the conductive particles with insulating particles increases. Low temperature and low voltage mounting becomes easier. By making it 60% or more, it becomes easy to maintain the conductive particles 1 in a predetermined particle dispersion state or a predetermined arrangement by the insulating resin layer 2 . In addition, since the contact area between the conductive particles with insulating particles and the resin increases during production (pressing into the film), it can be expected that the effects of the invention can be easily obtained. Further, by setting the content to 105% or less, it is possible to reduce the amount of resin in the insulating resin layer that causes the conductive particles between terminals to unnecessarily flow during anisotropic conductive connection.

As for the embedding ratio (Lb/D), 80% or more, preferably 90% or more, more preferably 96% or more of the total number of conductive particles with insulating particles contained in the anisotropic conductive film It means that it is a numerical value of the load ratio (Lb/D). Therefore, the embedding rate of 30% or more and 105% or less means that the total number of conductive particles with insulating particles contained in the anisotropic conductive film is 80% or more, preferably 90% or more, and more preferably 96% or more. It means that the ratio is 30% or more and 105% or less. Since the embedding ratio (Lb/D) of all the conductive particles with insulating particles is uniform in this way, the pressing load is uniformly applied to the conductive particles with insulating particles, so that the state of capturing the conductive particles with insulating particles at the terminal is improved, and the stability of conduction is improved.

The embedding rate (Lb/D) is obtained by extracting arbitrarily 10 or more regions with an area of 30 mm ² or more from the anisotropic conductive film, observing a part of the film cross section with an SEM image, and obtaining a total of 50 or more insulating particles. It can be determined by measuring the number of conductive particles attached. In order to further improve the accuracy, it may be obtained by measuring 200 or more conductive particles with insulating particles.

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

The effects of the slope 5b (FIG. 3A) of the insulating resin layer 5 around the exposed portion of the conductive particles with insulating particles and the undulations 5c (FIG. 3B) of the insulating resin layer immediately above the conductive particles with insulating particles are obtained. From the point of view of facilitating the More preferably less than 30%, more preferably 20 to 25%, the ratio of the maximum diameter Ld of the slope 5b around the exposed portion of the conductive particles 3 with insulating particles to the particle size D of the conductive particles 3 with insulating particles ( Ld/D) is preferably 100% or more, more preferably 100 to 150%, and the maximum depth Lf of the undulations 5c in the resin directly above the conductive particles 3 with insulating particles and the particles of the conductive particles 3 with insulating particles The ratio (Lf/D) to the diameter D is greater than 0, preferably less than 10%, more preferably 5% or less.

The diameter Lc of the exposed portion of the conductive particles 3 with insulating particles can be made equal to or less than the particle size D of the conductive particles 3 with insulating particles, preferably 10 to 90% of the particle size D. The conductive particles 3 with insulating particles may be exposed at one point at the top, or the conductive particles 3 with insulating particles may be completely buried in the insulating resin layer 5 so that the diameter Lc becomes zero. good.

In the present invention, the presence of the slopes 5b and the undulations 5c on the surface of the insulating resin layer 5 can be confirmed by observing the cross section of the anisotropic conductive film with a scanning electron microscope. can also be confirmed. Observation of the slope 5b and the undulation 5c is also possible with an optical microscope and a metallurgical microscope. Also, the magnitude of the slope 5b and the undulation 5c can be confirmed by adjusting the focus during image observation. The same is true even after reducing the slope or undulation by heat pressing as described above. This is because traces may remain.

(Composition of insulating resin layer)
The insulating resin layer 5 is preferably formed from a curable resin composition, and can be formed from, for example, a thermally polymerizable composition containing a thermally polymerizable compound and a thermal polymerization initiator. The thermally polymerizable composition may contain a photopolymerization initiator, if necessary.

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

A plurality of photopolymerization initiators that react to light with different wavelengths may be contained. As a result, the wavelengths used for photocuring of the resin constituting the insulating resin layer during the production of the anisotropic conductive film and for photocuring of the resin for bonding electronic parts together during anisotropic conductive connection can be changed. can be used properly.

In the photo-curing during the production of the anisotropic conductive film, all or part of the photopolymerizable compound contained in the insulating resin layer can be photo-cured. By this photocuring, the arrangement of the conductive particles 3 with insulating particles in the insulating resin layer 5 is maintained or fixed, and it is expected that short circuits are suppressed and trapping is improved. Moreover, the viscosity of the insulating resin layer in the manufacturing process of the anisotropic conductive film may be appropriately adjusted by this photocuring.

The amount of the photopolymerizable compound in the insulating resin layer is preferably 30% by mass or less, more preferably 10% by mass or less, and more preferably less than 2% by mass. This is because if the amount of the photopolymerizable compound is too large, the pushing force applied during connection increases.

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

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

Examples of thermal radical polymerization initiators include organic peroxides and azo compounds. In particular, organic peroxides that do not generate nitrogen causing air bubbles can be preferably used.

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

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

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

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

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

In order to adjust the melt viscosity, the thermally polymerizable composition may contain an insulating filler separately from the above-described insulating particle-containing conductive particles 3 . Examples include silica powder and alumina powder. The insulating filler preferably has a fine filler with a particle size of 20 to 1000 nm, and the blending amount may be 5 to 50 parts by mass with respect to 100 parts by mass of a thermally polymerizable compound (photopolymerizable composition) such as an epoxy compound. preferable.

The anisotropic conductive film of the present invention contains fillers, softeners, accelerators, anti-aging agents, colorants (pigments, dyes), organic solvents, ion catchers, etc., in addition to the insulating fillers described above. may let

(Layer thickness of insulating resin layer)
In the anisotropic conductive film of the present invention, the ratio (La/D) between the layer thickness La of the insulating resin layer 5 and the particle diameter D of the conductive particles 3 with insulating particles (La/D) has a lower limit of 0.3 or more for the reasons described later. and the upper limit can be 10 or less. Therefore, the ratio is preferably 0.3-10, more preferably 0.6-8, and even more preferably 0.6-6. Here, the particle diameter D of the conductive particles 3 with insulating particles means the average particle diameter. If the layer thickness La of the insulating resin layer 5 is too large, the conductive particles 3 with insulating particles tend to be displaced due to resin flow during anisotropic conductive connection, and the ability to capture the conductive particles 3 with insulating particles at the terminal is reduced. Since this tendency is remarkable when this ratio (La/D) exceeds 10, it is more preferably 8 or less, and even more preferably 6 or less. On the other hand, if the layer thickness La of the insulating resin layer 5 is too small and the ratio (La/D) is less than 0.3, the insulating resin layer 5 causes the conductive particles 3 with insulating particles to be dispersed in a predetermined state or in a predetermined state. Therefore, the ratio (La/D) is preferably 0.3 or more, and the ratio (La/D) is preferably 0.3 or more. The above is more preferable. Further, when the terminal to be connected is high-density COG, the ratio (La/D) between the layer thickness La of the insulating resin layer 5 and the particle diameter D of the conductive particles 3 with insulating particles is preferably 0.8 to 2. be.

<Embedded state of conductive particles with insulating particles in insulating resin layer>
As for the embedding state of the conductive particles 3 with insulating particles in the insulating resin layer 5, the embedding rate is preferably 30% or more and 105% or less. By setting the embedding rate to 30% or more, preferably 60% or more, the insulating resin layer 5 can maintain the conductive particles 3 with insulating particles in a predetermined particle dispersed state or in a predetermined arrangement. In addition, by setting the embedding rate to 105% or less, it is possible to reduce the amount of resin in the insulating resin layer that causes the conductive particles with insulating particles to unnecessarily flow during anisotropic conductive connection.

Here, the embedding ratio means the surface 5a of the insulating resin layer 5 in which the conductive particles 3 with insulating particles are embedded (the surface of the insulating resin layer 5 on which the conductive particles 3 with insulating particles are unevenly distributed ) and the deepest part of the conductive particles 3 with insulating particles embedded in the insulating resin layer 5 with respect to the surface 5a is the embedding amount Lb. It is the ratio (Lb/D) of the embedding amount Lb (FIG. 1B).

In the present invention, the value of the embedding rate (Lb/D) is 80% or more, preferably 90% or more, more preferably 96% or more of the total number of conductive particles contained in the anisotropic conductive film. It means that the numerical value of the embedding rate (Lb/D) is obtained. Therefore, the embedding rate of 30% or more and 105% or less means that the total number of conductive particles with insulating particles contained in the anisotropic conductive film is 80% or more, preferably 90% or more, and more preferably 96% or more. It means that the ratio is 30% or more and 105% or less. Since the embedding ratio (Lb/D) of the conductive particles with all the insulating particles is uniform in this way, the pressure load is uniformly applied to the conductive particles, so that the conductive particles are captured in a good state at the terminal, and the conduction is achieved. stability is improved.

The embedding ratio (Lb/D) is determined by extracting 10 or more arbitrarily areas with an area of 30 mm or more from the anisotropic conductive film, observing a part of the cross section of the film with an SEM image, and detecting a total of 50 or more conductive particles. It can be obtained by measuring. In order to further improve the accuracy, it may be determined by measuring 200 or more conductive particles.

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

<Method for producing anisotropic conductive film>
In one example of the method of manufacturing the anisotropic conductive film 10A shown in FIGS. 1A and 1B, the concave portions 31 of the transfer mold 30 are filled with the insulating particle-containing conductive particles 3 (FIG. 4A). The concave portions 31 are arranged in the same arrangement as the conductive particles 3 with insulating particles in the anisotropic conductive film.

As the transfer mold 30, for example, inorganic materials such as silicon, various ceramics, glass, metals such as stainless steel, etc., and organic materials such as various resins are processed by a known opening forming method such as photolithography. It is possible to use one in which the recess 31 is formed. Further, the transfer mold can have a shape such as a plate shape or a roll shape.

On the other hand, the insulating resin layer 5 is formed in a film shape on the release film 7, and the insulating resin layer 5 is put on the conductive particles 3 with insulating particles filled in the transfer mold 30 (FIG. 4C). Alternatively, before covering the conductive particles 3 with insulating particles with the insulating resin layer 5, the insulating particles 2 are separated from the conductive particles 1 by bringing a flat plate 32 into contact with the conductive particles 3 with insulating particles filled in the transfer mold 30. It may be separated (FIG. 4B) and then covered with an insulating resin layer 5 (FIG. 4C). Next, the insulating resin layer 5 is separated from the transfer mold 30 to obtain the insulating resin layer 5 onto which the conductive particles 3 with insulating particles have been transferred (FIG. 4D). In the step of transferring the insulating particle-attached conductive particles 3, since the transfer mold 30 and the insulating particles 2 rub against each other, the insulating particles 2 that are in contact with the bottom surface of the concave portion 31 of the transfer mold 30 (the insulating particles 2 of the region A1) is likely to detach from the conductive particles 3 with insulating particles. In addition, when the insulating resin layer 5 is placed on the insulating resin layer 5 on the conductive particles 3 with insulating particles in the transfer mold 30, a large force is applied to the insulating particles 2 that first come into contact with the insulating resin layer 5. Particles 2 (which will become insulating particles 2 in region A2) may also detach. For this reason, the insulating particles 2 may be present (spotted) on the film.

On the other hand, the insulating particles 2 in the film surface direction are maintained in the insulating resin layer 5 without being detached from the insulating resin layer 5 even after the insulating resin layer 5 is separated from the transfer mold 30 .

Therefore, in the conductive particles 3 with insulating particles after being transferred to the insulating resin layer 5, the conductive particles 1 among the insulating particles 2 constituting the conductive particles 3 with insulating particles are in contact with each other in the film thickness direction compared to before the transfer. The number of insulating particles 2 is reduced compared to the number of insulating particles 2 in contact with conductive particles 1 in the film surface direction.

Next, if necessary, the conductive particles 3 with insulating particles transferred to the insulating resin layer 5 are pressed by a flat plate or a roller 33 (FIG. 4E). At the time of this pressing, the insulating particles 2 forming the insulating particle-attached conductive particles 3, and the insulating particles 2 that were on the flat plate or roller 33 side (the insulating particles 2 that will be the region A1) come into contact with the flat plate or roller 33. relatively detached from the conductive particles 1 by

The pressing amount Lb when pressing the conductive particles 3 with insulating particles transferred to the insulating resin layer 5 with a flat plate or roller 33 is such that the embedding ratio (Lb/D) is preferably 30% or more and 105% or less, more preferably 60%. % or more and 105% or less.

In this way, it is possible to obtain an anisotropic conductive film 10A in which the number of insulating particles 2 in contact with the conductive particles 1 in the film thickness direction of the anisotropic conductive film is reduced among the number of insulating particles 2 in the conductive particles 3 with insulating particles. (Fig. 4F).

Further, in the method for manufacturing the anisotropic conductive film 10A described above, the number of the insulating particles 2 detached from the initial conductive particles 3 with insulating particles depends on the temperature and viscosity of the insulating resin layer 5 and the embedding rate (Lb /D) or the like.

<Deformation mode of anisotropic conductive film>
In the anisotropic conductive film of the present invention, like the anisotropic conductive film 10B shown in FIG. A low-viscosity insulating resin layer 6 having a low minimum melt viscosity may be laminated. Lamination of the low-viscosity insulating resin layer 6 fills the space formed by the electrodes and bumps of the electronic parts when anisotropically conductively connecting the electronic parts using the anisotropic conductive film, improving adhesion. can be made

The minimum melt viscosity ratio between the insulating resin layer 5 and the low-viscosity insulating resin layer 6 is preferably 2 or more, more preferably 5 or more, still more preferably 8 or more, and practically 15 or less. More specifically, the minimum melt viscosity of the low-viscosity insulating resin layer 6 is 3000 Pa·s or less, more preferably 2000 Pa·s or less, and particularly preferably 1000 to 2000 Pa·s. By making the low-viscosity insulating resin layer 6 low in viscosity in this way, the space formed by the electrodes and bumps of the electronic component can be easily filled with the low-viscosity insulating resin. becomes relatively small, and the conductive particles 3 with insulating particles between the terminals are less likely to flow due to the resin flow. Therefore, the adhesiveness between the electronic components can be improved without impairing the ability to capture the insulating particle-attached conductive particles 3 at the time of anisotropic conductive connection.

The minimum melt viscosity of the entire anisotropic conductive film 10B including the insulating resin layer 5 and the low-viscosity insulating resin layer 6 is preferably 200 to 4000 Pa·s.

The low-viscosity insulating resin layer 6 can be formed by adjusting the viscosity of the resin composition similar to that of the insulating resin layer 5 .

Moreover, in the anisotropic conductive film 10B, the layer thickness of the low-viscosity insulating resin layer 6 is preferably 4 to 20 μm. Alternatively, it is preferably 1 to 8 times the diameter of the conductive particles with insulating particles.

In the present invention, the anisotropic conductive film 10C (FIG. 6) may be formed after peeling the insulating resin layer 5 from the transfer mold 30 and before pressing the conductive particles 3 with insulating particles. An anisotropic conductive film 10D may be formed by laminating a flexible resin layer 6 (FIG. 7). In this case, the conductive particles with insulating particles may be present between the insulating resin layer and the low-viscosity insulating resin layer. In addition, it is preferable that the number of insulating particles on the conductive particles in plan view of the low-viscosity insulating resin layer-side film surface is smaller than the number of insulating particles on the conductive particles in plan view of the insulating resin layer-side film surface. Furthermore, if necessary, a low-viscosity insulating resin layer may be further laminated on the insulating resin layer 5 on the opposite side of the low-viscosity insulating resin layer 6 .

Moreover, a plurality of layers of the conductive particles 3 with insulating particles may be provided at different positions in the film thickness direction. These modified modes can be combined as appropriate.

<Electronic components connected with anisotropic conductive film>
The anisotropic conductive film of the present invention is capable of anisotropically conducting first electronic components such as IC chips, IC modules and FPCs and second electronic components such as FPCs, glass substrates, plastic substrates, rigid substrates and ceramic substrates. It can be preferably used when connecting. IC chips or wafers may be stacked to form multiple layers. In addition, the electronic components to be connected by the anisotropic conductive film of the present invention are not limited to the electronic components described above. It can be used for various electronic parts that have been diversifying in recent years.

<Connection method and connection structure using anisotropic conductive film>
The present invention provides a method for manufacturing a connection structure for anisotropically conductively connecting electronic components using the anisotropic conductive film of the present invention, and provides a connection structure obtained by this manufacturing method, that is, facing The terminals of the electronic component are anisotropically conductively connected by the conductive particles with insulating particles and the insulating resin layer, and the conductive particles with insulating particles that are not sandwiched between the opposing terminals are connected to the terminals. Provided is a connection structure containing conductive particles with insulating particles having insulating particle-missing regions facing in opposite directions.

In this connection structure, the conductive particles with insulating particles sandwiched between the terminals facing each other also contain the conductive particles with insulating particles having insulating particle-missing regions facing the opposing direction of the terminals. In this connection structure, the facing direction of the terminals corresponds to the film thickness direction of the anisotropic conductive film of the present invention used for manufacturing the connection structure, and the connection surface direction of the terminals corresponds to the anisotropic conductive film. Corresponds to the film plane direction. The region lacking insulating particles refers to a region where a portion of the surface of the conductive particles with insulating particles has a lower surface density of the insulating particles than the outer annular portion. Therefore, in this connection structure, the conductive particles with insulating particles sandwiched between the opposing terminals correspond to the regions A1 or A2 in which the number of insulating particles is reduced in the anisotropic conductive film described above, and the terminals It can be said that the number of insulating particles in contact with the conductive particles in the facing direction is less than the number of insulating particles in contact with the conductive particles in the terminal connection surface direction (direction perpendicular to the facing direction of the terminals). In such conductive particles with insulating particles, the direction of the insulating particle missing region of the conductive particles with insulating particles that are not sandwiched between the terminals facing each other is held by the insulating resin until immediately before the terminals are sandwiched. It is presumed that the orientation was maintained even after being clamped. The conductive particles with insulating particles sandwiched between the opposing terminals are preferable in terms of conduction stability because the insulating particle missing regions are in contact with at least one of the opposing terminals. It is more preferable to be in contact with both sides.

In addition, in this connection structure, the conductive particles with insulating particles in which the insulating particle-missing regions are oriented in the direction in which the terminals are opposed to each other are the regions A1 or A2 in which the number of insulating particles is reduced in the anisotropic conductive film, as described above. Since it corresponds to the conductive particles with insulating particles having the above-described relationship of (N _A3 +N _A4 )>(N _A1 +N _A2 ) in the anisotropic conductive film.

To conceptually explain the conductive particles with insulating particles in the region lacking insulating particles in the connection structure, when the conductive particles with insulating particles are a sphere, a partial region of the surface of the sphere corresponding to the central angle of 45° It can be said that this is a partial surface area of the sphere corresponding to the central angle of 45° when the surface density of the insulating particles is lower than that of the annular area corresponding to the outer central angle of 45° to 135°.

In this connection structure, the conductive particles with insulating particles that are not sandwiched between the opposing terminals are sandwiched between the non-formed regions of the terminal row in the electronic component, among the connecting surfaces of the opposing electronic component. Contains conductive particles with insulating particles in between. In this case, the conductive particles with insulating particles are, for example, when the facing electronic components are the first electronic component and the second electronic component, the terminal row non-formation region in the first electronic component and the terminal row in the second electronic component It is the conductive particles with insulating particles sandwiched in the facing direction of the electronic component by the non-formation regions.

Further, in this connection structure, the conductive particles with insulating particles that are not sandwiched between the opposing terminals are in the space between the terminals of the opposing electronic component when the terminal rows are formed in the electronic component with a predetermined inter-terminal space. Including conductive particles with insulating particles between them.

In other words, the conductive particles with insulating particles that are not sandwiched between the opposing terminals mean the majority of the conductive particles with insulating particles that do not contribute to the connection in the connection structure.

Generally, in the connection structure, among the conductive particles with insulating particles that are not sandwiched between opposing terminals, there are those that have moved relative to the state before heating and pressurization due to heating and pressurization during anisotropic conductive connection. Some are included and are oriented differently. The extent to which the direction changes depends on the position of the conductive particles with insulating particles with respect to the terminal, the viscosity of the insulating particle layer, the conditions for heating and pressing, etc. It also includes those that maintain Therefore, when the anisotropic conductive film used in the production of the connection structure is the anisotropic conductive film of the present invention, at least a part of the conductive particles with insulating particles that are not sandwiched between the opposing terminals include the insulating particles Since the lacking region is oriented in the facing direction of the facing terminals, it can be seen that this is the connection structure of the present invention. In particular, when conductive particles lacking regions in a connection structure contain conductive particles with insulating particles directed in the facing direction of opposing terminals in a lump in a certain region, the connection structure is the connection structure of the present invention. It is easy to see that it is a body.

The anisotropic conductive film is sometimes cut into a size approximately equal to one of the outer shapes of the electronic component and used, but is generally cut to be larger than one of the outer shapes of the electronic component. That is, it may contain areas (far enough from the tool) that do not contribute to the connection. Therefore, there may be a region lacking insulating particles facing the direction in which the terminals face each other in the anisotropic conductive film on the outer side between the electronic components facing each other. can be done.

In addition, when the conductive particles with insulating particles are regularly arranged in the anisotropic conductive film used for manufacturing the connection structure, the conductive particles with insulating particles that are not sandwiched between the opposing terminals are also arranged in the connection structure. may also be found to maintain the regularity of In this case, it can be easily confirmed that the insulating particle-missing region is oriented in the direction in which the terminals face each other in the conductive particles with insulating particles in which the regularity of arrangement is found. Moreover, (N _A3 +N _A4 )>(N _A1 +N _A2 ) can be easily confirmed for the anisotropic conductive film used for its production.

Note that the structure in the manufacturing process of the bonded structure of the present invention, in which the anisotropic conductive film of the present invention is attached to one electronic component, but the other electronic component is not yet connected. structure (an intermediate product in the connection process, in other words, an anisotropic conductive film-attached electronic component), the conductive particles with insulating particles in the anisotropic conductive film are the insulating particles in the above-described connection structure It has the same features as the conductive particles.

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 insulating resin layer 5, the anisotropic The side of the anisotropic conductive film where the conductive particles 3 with insulating particles are embedded in the surface is temporarily pressure-bonded, and the side of the temporarily pressure-bonded anisotropic conductive film on which the conductive particles 3 with insulating particles 3 are not embedded in the surface is covered with an IC chip or the like. can be manufactured by combining the first electronic components of and thermocompression bonding. When the insulating resin layer of the anisotropic conductive film contains not only a thermal polymerization initiator and a thermally polymerizable compound, but also a photopolymerization initiator and a photopolymerizable compound (which may be the same as the thermally polymerizable compound), A crimping method using both light and heat may be used. In this way, unnecessary movement of the conductive particles with insulating particles can be minimized. Alternatively, the side where the conductive particles 3 with insulating particles are not embedded may be temporarily attached to the second electronic component for use. Note that the anisotropic conductive film may be temporarily attached to the first electronic component instead of the second electronic component.

Further, when the resin layer of the anisotropic conductive film is formed of a laminate of the insulating resin layer 5 and the low-viscosity insulating resin layer 6, the insulating resin layer 5 is applied to the second electronic component such as various substrates. The first electronic component such as an IC chip is aligned and mounted on the low-viscosity insulating resin layer 6 of the anisotropic conductive film temporarily bonded and temporarily pressed, and then thermally pressed. The low-viscosity insulating resin layer 6 side of the anisotropic conductive film may be temporarily attached to the first electronic component for use.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples.
Examples 1-10
(1) Production of anisotropic conductive film Resin compositions for forming an insulating resin layer and a low-viscosity insulating resin layer were prepared according to the formulations shown in Table 1, respectively.

A resin composition that forms an insulating resin layer is applied on a PET film having a film thickness of 50 μm with a bar coater, dried in an oven at 80 ° C. for 5 minutes, and the insulating thickness shown in Table 2 is applied to the PET film. A resin layer was formed. Similarly, a low-viscosity insulating resin layer was formed on the PET film with the thickness shown in Table 2.

On the other ^hand , the conductive particles with insulating particles are arranged in a square lattice as shown in FIG. made. That is, the convex pattern of the mold (number density: 28000 pieces/mm ² ) is a square lattice arrangement, the pitch of the convexes on the lattice axis is twice the average particle diameter, and the lattice axis and the anisotropic conductive film are short. A mold having an angle θ with the hand direction of 15° is prepared, and molten pellets of a known transparent resin are poured into the mold and cooled to solidify, so that the recesses are arranged as shown in FIG. 1A. A resin mold of the pattern was formed.

In addition, a mold with a random convex pattern (number density: 28000 pieces/mm ² ) was prepared, and a resin mold having concave portions in a random pattern was formed using the mold. At this time, the distance between adjacent conductive particles with insulating particles was set to be 0.5 times or more the average diameter of the conductive particles.

As the conductive particles with insulating particles, insulating fine particles (average particle size 0 0.3 μm) was prepared, and the recesses of the resin mold were filled with the conductive particles with insulating particles, and the insulating resin layer was covered thereon.

In Examples 1 to 6, the insulating resin layer was pressed at 60° C. and 0.5 MPa, and the insulating resin layer was peeled off from the resin mold, thereby transferring the conductive particles with insulating particles to the insulating resin layer. . At this time, the embedding rate (Lb/D) of the conductive particles with insulating particles in the insulating resin layer was 30% by cross-sectional observation by SEM. Moreover, there were no depressions around the conductive particles with insulating particles on the surface of the insulating resin layer to which the conductive particles with insulating particles were transferred (see FIG. 2). In Examples 7 to 10, the conductive particles with insulating particles were transferred to the insulating resin layer in the same manner as in Examples 1 to 6, but there were dents in the insulating resin layer around the conductive particles with insulating particles after transfer. The temperature at which the conductive particles with insulating particles are pressed against the insulating resin layer is set lower than 60° C. so that this can be achieved.

Next, in Examples 3 to 10, the conductive particles with insulating particles on the insulating resin layer were pressed to push the conductive particles with insulating particles into the insulating resin layer at a pressing ratio (Lb/D) of 100%. The temperature and pressure at the time of pressing were the same as the temperature and pressure at the time of transferring the conductive particles with insulating particles from the resin mold to the insulating resin layer. As a result, in Examples 3 to 6, there was no dent in the insulating resin layer around the conductive particles with insulating particles after pressing, and in Examples 7 to 10, the insulating resin layer around the conductive particles with insulating particles after pressing. A dent was formed in the (see FIG. 3A).

In Examples 1 and 2 (embedding rate of 30%) and Examples 3 and 4 (embedding rate of 100%), a low-viscosity insulating resin layer was formed on the surface of the insulating resin layer on which the conductive particles with insulating particles were transferred. was laminated to form an anisotropic conductive film (see FIG. 5).

On the other hand, in Examples 5 to 10 (embedding rate 100%), no low-viscosity insulating resin layer was laminated. Of these, in Examples 7 to 10, the conductive particles with insulating particles were pressed into the insulating resin layer, and recesses were formed in the insulating resin layer around the conductive particles with insulating particles. In No. 10, the insulating resin layer having the dents was heat-pressed under conditions that did not interfere with the anisotropic conductive connection to eliminate the dents.

Comparative Examples 1-4
In Comparative Examples 1 to 4, insulating coated conductive particles (coat thickness 0.1 to 0.5 μm) obtained by applying an insulating coat to the entire surface of metal-coated resin particles (AUL703, average particle size 3 μm, manufactured by Sekisui Chemical Co., Ltd.). is used instead of the conductive particles with insulating particles in the above-described example, and the resin mold is filled so that the insulating coated conductive particles have the arrangement or arrangement shown in Table 2, and the insulating resin layer is coated with the insulating coated conductive particles. The particles were transferred (30% pushing ratio), and in Comparative Examples 3 and 4, the insulating coated conductive particles transferred to the insulating resin layer were pushed into the insulating resin layer at a pushing ratio of 100%. Then, a low-viscosity insulating resin layer was laminated on the transfer-adhering surface or pressing surface of the insulating-coated conductive particles.

(2) Particle arrangement state (2-1) Independent particle number ratio Using a scanning electron microscope (SEM), the front and back film surfaces (low-viscosity insulating resin For laminated layers, 100 insulating particle-containing conductive particles or insulating coated conductive particles are observed for each of the low-viscosity insulating resin layer side surface and the opposite surface), and the insulating particle-containing conductive particles that are not in contact with each other are observed. The number of particles or insulation-coated conductive particles was counted, and the ratio of the number to the total number (that is, independent particle number ratio) was determined. As a result, in each example and comparative example, the independent particle number ratio exceeded 99%.

(2-2) Insulating Particle Coverage The insulating particle coverage of the electrically insulating particle-attached electrically conductive particles (the electrically insulating particle-attached electrically conductive particles before being embedded in the insulating resin layer) used in the production of the anisotropic conductive film of the example was determined. . The insulating particle coverage rate is measured by observing 100 conductive particles with insulating particles using a scanning electron microscope (SEM), and measuring the number of insulating particles per conductive particle for each conductive particle with insulating particles. It was calculated from the number of particles, the area of one insulating particle-attached conductive particle in plan view, and the area of one insulating particle in plan view. As a result, the insulating particle coverage of the conductive particles with insulating particles used in the production of the anisotropic conductive film was 67%.

(2-3) Coating State of Insulating Particles after Production of Anisotropic Conductive Film The coating state of the insulating particles in the conductive particles with insulating particles dispersed in the anisotropic conductive film of the example was examined with a scanning electron microscope (SEM). It was obtained by cross-sectional observation by In this cross-sectional observation, 100 conductive particles with insulating particles were measured, and the number of insulating particles in the regions _A1 , _A2 , _A3 , and _A4 shown in FIG. Examined. As a result, there was no particular difference in the number of insulating particles between the region A3 and the region A4 in each example. Moreover, in Examples 3 to 10, the number of insulating particles in the region A1 was significantly reduced compared to the number of insulating particles in the region A2 compared to the first example.

(3) Evaluation After cutting the anisotropic conductive film of each example and comparative example in an area sufficient for connection and evaluation, using the cut anisotropic conductive film, as described below, (a ) initial conduction resistance, (b) conduction reliability, (c) short-circuit occurrence rate, and (d) conductive particle trapping ability were measured or evaluated. Table 2 shows the results.

(a) Initial conduction resistance The anisotropic conductive film of each example and comparative example was sandwiched between an IC for evaluating conduction characteristics and a glass substrate, and heated and pressed (180 ° C., 60 MPa, 5 seconds). A connection for evaluation was obtained, the conduction resistance of the obtained connection for evaluation was measured, and the measured initial conduction resistance was evaluated according to the following criteria.
A: 0.3 Ω or less B: More than 0.3 Ω, 0.4 Ω or less C: More than 0.4 Ω If the evaluation is B, there is no practical problem. If it is A evaluation, it is more preferable.

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

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

Glass substrate Glass material Corning 1737F
Outer diameter 30×50mm
thickness 0.5mm
Electrode ITO wiring

(b) Conduction reliability The connection for evaluation prepared in (a) is placed in a constant temperature bath at a temperature of 85 ° C and a humidity of 85% RH for 500 hours. The conduction resistance was evaluated according to the following criteria.

S: 3.0 Ω or less A: More than 3.0 Ω, 4.0 Ω or less B: More than 4.0 Ω, 6.0 Ω or less C: More than 6.0 Ω If the evaluation is B, there is no practical problem. A rating or higher is more preferable.

(c) Short-circuit occurrence rate The anisotropic conductive film of each example and comparative example was used as an IC for insulation test evaluation (comb-teeth TEG (test element group) with a 7.5 μm space) and a glass substrate with a corresponding terminal pattern. and a connection object for evaluation is obtained by heating and pressurizing in the same manner as the initial conduction resistance, and the short occurrence rate in the obtained connection object for evaluation is measured with a digital multimeter (digital multimeter 7561, Yokogawa Electric Corporation) ). The specifications of this insulation test evaluation IC are shown below.

IC for insulation test evaluation
Outline 1.5×13mm
thickness 0.5mm
Bump specifications Gold plating, size 25×140 μm, distance between bumps 7.5 μm, bump height 15 μm

The measured short occurrence rate was evaluated according to the following criteria.
A: less than 50 ppm
B: 50 ppm or more and 200 ppm or less C: More than 200 ppm If the evaluation is B, there is no practical problem.

(d) Conductive particle trapping property An IC for evaluating conductive particle trapping property is used, and the IC for evaluation and the ITO coated substrate corresponding to the terminal pattern are shifted by 6 μm in alignment and heated and pressurized (180 ° C., 60 MPa, 5 seconds), the number of trapped conductive particles was measured for 100 particles in a region of 6 μm×66.6 μm where the bumps of the IC for evaluation and the terminals of the substrate overlapped, and the minimum number of trapped particles was obtained and evaluated according to the following criteria.

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

Conductive particle trapping evaluation criteria OK: 3 or more NG: less than 3

From Table 2, in the anisotropic conductive films of Examples 1 to 10, the number density of the insulating particles in the conductive particles with insulating particles is lower in the regions A2 and A1 than in the regions A3 and A4. In Examples 3 to 10 in which the conductive particles with insulating particles were pressed into the insulating resin layer during manufacture, the number density of the insulating particles was significantly lower in the region A1 than in the region A2. As a result, the number density of the insulating particles 2 in the regions A2 and A1 contacting the conductive particles in the film thickness direction becomes even smaller than the number density of the insulating particles 2 in the regions A3 and A4 contacting the conductive particles 1 in the film surface direction. It can be seen that Examples 3 and 4 are superior to Examples 1 and 2 in reliability of conduction. On the other hand, in Comparative Examples 1 to 4 using resin-coated conductive particles, the conduction reliability was inferior.

In addition, in the results of Table 2, a comparison between Examples 1 and 2, a comparison between Examples 3 and 4, a comparison between Examples 5 and 6, a comparison between Examples 7 and 8, a comparison between Examples 9 and 10, and a comparison example By comparing 1 and 2 and comparing Comparative Examples 3 and 4, the case where the conductive particles with insulating particles are arranged in a square lattice and the case where they are randomly arranged, and the case where the insulating coated conductive particles are arranged in a square lattice and random Although there is no difference in conduction resistance, short-circuit occurrence rate, and conductive particle trapping property between the case of arranging in It was easier to confirm the indentation than in the case of random arrangement.

In addition, in Examples 5 and 6 in which there is no dent in the insulating resin layer around the conductive particles with insulating particles, and in Examples 7 and 8 in which the insulating resin layer around the conductive particles with insulating particles has dents, the dents In Examples 9 and 10, in which the problem was solved by hot pressing, the initial conduction resistance, conduction reliability, short-circuit occurrence rate, and conductive particle trapping property were evaluated as good. From this, it can be seen that the electrically conductive particles with insulating particles did not unnecessarily move due to the resin flow in this example regardless of the presence or absence of the recesses.

REFERENCE SIGNS LIST 1 conductive particles 2 insulating particles 3 conductive particles with insulating particles 5 insulating resin layer 5a surface of insulating resin layer 5b recess 5c recess 6 low-viscosity insulating resin layer 7 release films 10A, 10B, 10C, 10D anisotropic conductive film 30 Transfer mold 31 Concave portion 32 Flat plate 33 Flat plate or roller A1, A2, A3, A4 Region D Particle diameter of conductive particles with insulating particles La Layer thickness of insulating resin layer Lb Insulated from the surface adjacent to conductive particles with insulating particles Distance to deepest part of conductive particles with particles Lc Diameter of exposed portion of conductive particles with insulating particles Ld Maximum diameter of inclination around exposed portion of conductive particles with insulating particles Le Angle around exposed portion of conductive particles with insulating particles Maximum depth of Lf Maximum depth of undulations in the resin directly above the conductive particles with insulating particles

Claims (9)

A method for producing an anisotropic conductive film in which conductive particles with insulating particles having insulating particles attached to the surface of the conductive particles are dispersed in an insulating resin layer, wherein the conductive particles with insulating particles include the conductive particles and the film In a method for producing an anisotropic conductive film in which the number of insulating particles in contact in the thickness direction is less than the number of insulating particles in contact with the conductive particles in the film surface direction,
filling conductive particles with insulating particles into the recesses of the transfer mold in which the recesses are formed;
The insulating resin layer formed on the release film is covered from the insulating resin layer side on the surface of the transfer mold on which the concave portions filled with the conductive particles with insulating particles are formed, and
Transferring the conductive particles with insulating particles filled in the recesses to the insulating resin layer,
A manufacturing method for obtaining an anisotropic conductive film comprising an insulating resin layer to which conductive particles with insulating particles have been transferred by separating the insulating resin layer from a transfer mold. 2. The manufacturing method according to claim 1, wherein a low-viscosity insulating resin layer having a lower minimum melt viscosity than the insulating resin layer is laminated on the surface of the anisotropic conductive film on which the conductive particles with insulating particles have been transferred. 3. The manufacturing method according to claim 2, wherein the conductive particles with insulating particles are transferred so as to exist between the insulating resin layer and the low-viscosity insulating resin layer. After filling the conductive particles with insulating particles in the recesses of the transfer mold, a flat plate is brought into contact with the conductive particles with insulating particles filled in the recesses to separate the insulating particles from the conductive particles with insulating particles, and then the insulating resin layer is formed. The manufacturing method according to any one of claims 1 to 3, which is covered. After transferring the conductive particles with insulating particles to the insulating resin layer, the conductive particles with insulating particles are pushed into the insulating resin layer with a flat plate or a roller, and the insulating particles in contact with the flat plate or roller are separated from the conductive particles with insulating particles. The manufacturing method according to any one of claims 1 to 4. Among the front and back surfaces of the insulating resin layer, the ratio of the distance Lb from the surface where the conductive particles with insulating particles are adjacent to the deepest part of the conductive particles with insulating particles to the particle diameter D of the conductive particles with insulating particles (Lb The manufacturing method according to claim 5, wherein the pressing is performed with a flat plate or a roller so that /D) is 30 to 105%. The number of insulating particles overlapping the conductive particles in plan view of one of the front and back film surfaces of the anisotropic conductive film is less than the number of insulating particles overlapping the conductive particles in plan view of the other film surface. The manufacturing method according to any one of claims 1 to 6. The manufacturing method according to any one of claims 1 to 7, wherein the recesses are formed in the transfer mold so that the conductive particles with insulating particles are arranged without contact with each other. 8. The production according to claim 7, wherein the number of insulating particles on the conductive particles in plan view of the film surface on the low-viscosity insulating resin layer side is smaller than the number of insulating particles on the conductive particles in plan view on the film surface on the insulating resin layer side. Method.

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