Anisotropic Conductive Film

Abstract

To enable use as a product within specifications as long as no problem occurs in anisotropic conductive connection even if conductive particles are missing from a predetermined alignment arrangement. [Solution] An anisotropic conductive film (1A) having a length of 5 m or more and having a regular arrangement region in which conductive particles (2) are regularly arranged in an insulating resin binder (3), wherein within the regular arrangement region there is a standard region (2Y) in which there are no portions (2Y) in which a predetermined number or more of conductive particles are missing consecutively, the standard region being of a predetermined width in the short direction of the anisotropic conductive film (1A) and of a predetermined length or more in the longitudinal direction of the anisotropic conductive film (1A).

Description

[Technical Field]

[0001] The present invention relates to an anisotropic conductive film. [Background technology]

[0002] Anisotropic conductive films, which have conductive particles dispersed in an insulating resin binder, are widely used when mounting electronic components such as IC chips on substrates. Due to the recent trend toward narrower bump pitches associated with higher density mounting of electronic components, there is a strong demand for anisotropic conductive films that can enhance the capture of conductive particles in the bumps and prevent short circuits.

[0003] To meet this demand for anisotropic conductive films, various methods for regularly aligning conductive particles have been investigated. For example, a technique in which conductive particles are spread on a stretched film and then biaxially stretched to align the conductive particles in a single layer (Patent Document 1) and a technique in which conductive particles are held on a substrate using magnetism and then transferred to an adhesive film to form a predetermined array of conductive particles (Patent Document 2) are known. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5147048 [Patent Document 2] Patent No. 4887700 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the biaxial stretching method, it is difficult to precisely align the conductive particles in predetermined positions, and gaps often occur in the arrangement of the conductive particles. Although the transfer method allows for more precise arrangement of the conductive particles than the biaxial stretching method, it is difficult to completely eliminate gaps in the conductive particles across the entire surface of the anisotropic conductive film.

[0006] Furthermore, because anisotropic conductive film products are generally manufactured in lengths of 5 meters or more, it is difficult and unrealistic to manufacture a product with absolutely no missing conductive particles along its entire length. For example, if a product with even one missing particle is deemed defective due to being out of specification, the product yield will decrease and the manufacturing cost will increase. On the other hand, if there are significant missing conductive particles in the product, problems will arise with the connection stability of the anisotropic conductive connection.

[0007] Therefore, the object of the present invention is to enable an anisotropic conductive film in which gaps exist in the predetermined regular arrangement of conductive particles to be used for anisotropic conductive connection in substantially the same manner as an anisotropic conductive film without gaps. [Means for solving the problem]

[0008] The present inventors have found that even when there are gaps in the predetermined regular arrangement of conductive particles, no problems arise in the anisotropic conductive connection in the following cases (a) to (c).

[0009] (i) If there are continuous gaps in the specified regular arrangement of conductive particles, poor conductivity is likely to occur, and this tendency is particularly strong if the gaps are continuous in the longitudinal direction of the anisotropic conductive film.However, even if there are continuous gaps in the longitudinal direction of the anisotropic conductive film, poor conductivity is unlikely to occur if the number of continuous gaps is less than a specified number depending on the object to be connected.

[0010] (b) When an anisotropic conductive film is used in a FOG (film on glass) or the like where the area of ​​each bump is relatively large, the bump width is generally at most about 200 μm. Therefore, if there are 10 or more conductive particles within a range of 200 μm in the longitudinal direction of the anisotropic conductive film, even if there are gaps in the regular arrangement of the conductive particles, there will be virtually no connection problems.

[0011] (c) When an anisotropic conductive film is used in a device such as a COG (chip on glass) in which the bumps are located at specific locations (for example, there are rows of bumps at both ends in the short direction) and the area of ​​each bump is relatively small, if there are no areas along both ends of the anisotropic conductive film in the short direction where conductive particles are missing in succession for a predetermined number or more (i.e., areas where the particles are missing to a level that would cause practical problems) when aligning the ends of the anisotropic conductive film in the short direction with the terminal rows of the chip, then even if there are more than a predetermined number of conductive particles missing in succession in the center of the short direction, connection problems are unlikely to occur.

[0012] The present invention was made based on these findings and provides an anisotropic conductive film having a length of 5 m or more and having a regular arrangement region in which conductive particles are regularly arranged in an insulating resin binder, wherein the regular arrangement region has a standard area with no areas where a predetermined number or more of conductive particles are missing in a continuous manner, the standard area having a predetermined width in the short direction of the anisotropic conductive film and a predetermined length or more in the longitudinal direction of the anisotropic conductive film.

[0013] The anisotropic conductive film of the present invention has a configuration in which, even if conductive particles are missing from a predetermined regular arrangement, they can achieve an anisotropic conductive connection substantially equivalent to that of a non-missing anisotropic conductive film. In other words, the configuration is significant in that the amount of conductive particles present is reduced to a level that does not degrade the properties of the anisotropic conductive film. Therefore, the anisotropic conductive film of the present invention enables a reduction in the amount of metal used in the conductive particles, contributing not only to reduced manufacturing costs but also to reduced environmental impact and relaxed specification requirements for anisotropic conductive film products (improved manufacturing yield). To achieve stable conductivity with the minimum number of conductive particles required for anisotropic connection, it is preferable that the regularly arranged region and the standard region coincide. However, non-standard regions, where a predetermined number or more of conductive particles are missing in a continuous sequence, may exist as long as the effects of the present invention are not significantly impaired.

[0014] In particular, as an anisotropic conductive film for use in COG (chip on glass), where the area of ​​each bump is relatively small and the number of bumps is large, an embodiment is provided in which the anisotropic conductive film has a standard area along at least the end region in the short direction.

[0015] In addition, as an anisotropic conductive film for use in FOG (film on glass), for example, where the individual bump areas are relatively large, we provide an embodiment in which 10 or more conductive particles are present in an arbitrarily selected region of 200 μm in the longitudinal direction across the entire width of the anisotropic conductive film.

[0016] The present invention also provides a method for producing an anisotropic conductive film, in which a wide original sheet of anisotropic conductive film, in which conductive particles are regularly arranged in an insulating resin binder, is cut lengthwise so as to avoid any irregularities where a predetermined number or more of conductive particles are missing from the regular arrangement, or so that the irregularities are positioned in the intended position in the short direction of the film, to produce an anisotropic conductive film having a length of 5 m or more.

[0017] The present invention further provides a method for producing an anisotropic conductive film, which involves removing non-standard areas where a predetermined number or more of conductive particles are missing from an anisotropic conductive film having a standard arrangement region in which conductive particles are regularly arranged in an insulating resin binder, and then splicing the anisotropic conductive films after removal to produce an anisotropic conductive film with a length of 5 m or more. If the length is 5 m or more, it can be installed in an anisotropic connection device for continuous production, making it easy to verify. In other words, when replacing an anisotropic conductive film used in a general-purpose anisotropic connection structure, the verification load can be reduced.

[0018] The present invention also provides a method for manufacturing a connection structure in which a first electronic component having a terminal row and a second electronic component having a terminal row are anisotropically conductively connected to each other by thermocompression bonding the first electronic component having a terminal row and the second electronic component having a terminal row via an anisotropic conductive film having a regular arrangement region in which conductive particles are regularly arranged in an insulating resin binder, the method comprising: The anisotropic conductive film is an anisotropic conductive film in which a standard area, in which there are no areas where a predetermined number or more of conductive particles are continuously missing, is formed with a predetermined width in the short-side direction of the anisotropic conductive film and a predetermined length in the long-side direction of the anisotropic conductive film, within the standard arrangement area; A method for manufacturing a connection structure is provided that aligns the standard area with the terminal row of an electronic component.

[0019] In this manufacturing method, when the first electronic component and the second electronic component each have a plurality of terminal rows and standard areas are formed in parallel on the anisotropic conductive film, It is preferable that the area between adjacent standard areas be aligned with the area between the terminal rows. [Effects of the Invention]

[0020] According to the method for manufacturing an anisotropic conductive film of the present invention, it is possible to produce an anisotropic conductive film by extracting a practically acceptable area from an anisotropic conductive film that has previously been determined to be defective due to missing conductive particles. Furthermore, according to the method for manufacturing a connection structure of the present invention, even if the anisotropic conductive film used to manufacture the connection structure has an area determined to be problematic due to missing conductive particles, if a standard area in which there are no areas where more than a predetermined number of consecutive conductive particles are missing extends over a predetermined width in the short direction of the anisotropic conductive film and a predetermined length in the long direction of the anisotropic conductive film, the standard area is aligned with the terminal row of the electronic component. Therefore, the yield of anisotropic conductive film manufacturing can be improved without compromising the reliability of the anisotropic conductive connection. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a plan view illustrating the arrangement of conductive particles in an anisotropic conductive film 1A according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view illustrating the arrangement of conductive particles in an anisotropic conductive film 1B according to the embodiment. [Figure 3]FIG. 3 is a plan view illustrating the arrangement of conductive particles in an anisotropic conductive film 1C according to the embodiment. [Figure 4] FIG. 4 is a plan view showing the positions of the conductive particles in the anisotropic conductive film for COG where the arrangement is out of standard. [Figure 5] FIG. 5 is a cross-sectional view of an anisotropic conductive film 1a according to an embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view of an anisotropic conductive film 1b according to the embodiment. [Figure 7] FIG. 7 is a cross-sectional view of an anisotropic conductive film 1c according to an embodiment. [Figure 8] FIG. 8 is a cross-sectional view of an anisotropic conductive film 1d according to the embodiment. [Figure 9] FIG. 9 is a cross-sectional view of an anisotropic conductive film 1e according to an embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing the bump arrangement of the evaluation IC. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will now be described in detail with reference to the drawings, in which the same reference numerals represent the same or equivalent components.

[0023] <Anisotropic conductive film> (Overall structure of anisotropic conductive film) The anisotropic conductive film of the present invention has regions (orderly arranged regions) in which conductive particles are regularly arranged in an insulating resin binder, and preferably the conductive particles are spaced apart and regularly arranged (e.g., in a lattice pattern) in plan view. Here, one regularly arranged region may extend over the entire surface of the anisotropic conductive film, or multiple groups of conductive particles may be arranged as regularly arranged regions spaced apart from each other over the entire surface.

[0024] The anisotropic conductive film of the present invention has a regularly arranged region, which allows for accurate inspection and detection of missing conductive particles relative to the regular arrangement of conductive particles. The anisotropic conductive film of the present invention has, within such regularly arranged region, a standard region in which there are no locations where a predetermined number or more of consecutive conductive particles are missing, the standard region having a predetermined width in the short-side direction of the anisotropic conductive film and a predetermined length or more in the long-side direction of the anisotropic conductive film. When multiple groups of conductive particles are arranged separately from each other as regularly arranged regions over the entire surface of the anisotropic conductive film, each regularly arranged region has an internal standard region having a predetermined width in the short-side direction of the anisotropic conductive film and a predetermined length or more in the long-side direction of the anisotropic conductive film.

[0025] In a typical anisotropic conductive connection structure, the transverse direction of the anisotropic conductive film corresponds to the longitudinal direction of the terminal. This allows the terminal to capture conductive particles aligned in the transverse direction of the anisotropic conductive film more easily, making it easier to relax the anisotropic conductive connection conditions. Therefore, when the anisotropic conductive film is pressed against the connection tool along its entire transverse direction to contribute to an anisotropic conductive connection, the pressing width conditions in the transverse direction of the anisotropic conductive film can also be relaxed. Specifically, the upper limit of the "predetermined width" in the transverse direction of the anisotropic conductive film is preferably 95% or less, more preferably 90% or less, of the transverse direction of the anisotropic conductive film. Meanwhile, the lower limit is preferably 10% or more, more preferably 20% or more. Furthermore, the position of the "predetermined width" in the short-side direction of the anisotropic conductive film is preferably located at a location other than the center of the short-side direction of the anisotropic conductive film, i.e., at the ends (both ends), to facilitate application to anisotropic connections of general COG and other IC chips and similar terminal layouts. The widths of the standard areas at both ends may be the same or different, in order to accommodate the required terminal layout.

[0026] On the other hand, with regard to the standard area, "a predetermined length or more" in the longitudinal direction of the anisotropic conductive film (i.e., the short-side direction of the terminal in a general anisotropic conductive connection structure) means, based on an anisotropic conductive connection structure (for example, a small component mounting unit of about 10 mm square such as a camera module), 5 mm or more, preferably 10 mm or more, and more preferably 20 mm or more (equivalent to 0.4% of the anisotropic conductive film length of 5 m). In addition, in the case of a large anisotropic conductive connection structure (for example, a large display of 80 inches or more), the regular arrangement area may be 2000 mm or more.

[0027] Regarding the range within the standard, the longer the upper limit of the "predetermined length" of the anisotropic conductive film in the longitudinal direction, the better, since the anisotropic conductive film itself is a good product. Therefore, there is no particular limit to the "predetermined length." However, from the perspective of image inspection during quality control of anisotropic conductive films, limiting the length to a certain extent can facilitate quality information management. For example, dividing the length into certain lengths makes it easier to compare data for each length. Another advantage is that the image data volume can be simply reduced. As an example of the upper limit of the "predetermined length," a length of 1000 m or less, preferably 500 m or less, more preferably 350 m or less, and even more preferably 50 m or less, makes it easier to process and manage image data during inspection.

[0028] From the viewpoint of stable connection, it is preferable that the regular arrangement region and the regular arrangement region are as close as possible to each other, and even more preferably, they coincide with each other. As long as the effects of the present invention are not significantly impaired, the regular arrangement region may contain areas where a predetermined number or more of conductive particles are missing (non-standard areas). Outside the regular arrangement region of the anisotropic conductive film, blank areas where no conductive particles exist and random arrangement regions where conductive particles are randomly arranged may also exist.

[0029] The length of the anisotropic conductive film of the present invention is preferably 5 m or more, more preferably 10 m or more, and even more preferably 50 m or more to stabilize the productivity of connection structures using anisotropic conductive connection. On the other hand, if the film length is too long, labor is required for setting up the film in the equipment, transporting it, etc., or the cost of modifying the equipment increases. Therefore, the length is preferably 5,000 m or less, more preferably 1,000 m or less, and even more preferably 500 m or less. The film width is not particularly limited, but is, for example, 0.5 to 5 mm.

[0030] Because the length of an anisotropic conductive film is long relative to its width, it is preferably wound on a reel. The wound body may be made of a plurality of anisotropic conductive films joined together. A splicing tape can be used to join the anisotropic conductive films. There are no particular restrictions on the thickness of the splicing tape, but if it is too thick, it may have adverse effects on resin overflow and blocking, so a thickness of 10 to 40 μm is preferred.

[0031] (Arrangement of conductive particles) An example of a regular arrangement of conductive particles is a square lattice arrangement, as in the anisotropic conductive film 1A shown in FIG. 1. Other examples of regular arrangements of conductive particles include rectangular lattice, oblique lattice, and hexagonal lattice arrangements. Conductive particles may be arranged in a linear array at a predetermined interval, and the array may be parallel to each other at a predetermined interval. Furthermore, as in the anisotropic conductive film 1B shown in FIG. 2, conductive particles 2 may occupy multiple vertices of a regular polygon (a regular hexagon in this embodiment) when regular polygons are arranged without gaps, so that the arrangement of conductive particles 2 can be thought of as a trapezoidal repeat unit 5 consisting of conductive particles 2a, 2b, 2c, and 2d. The trapezoidal repeat unit is an example of a regular arrangement of conductive particles, and they may be spaced apart, or a collection of multiple repeat units may form a region of regularly arranged conductive particles. Here, the repeat unit 5 is a repeating unit of an arrangement of conductive particles formed by sequentially connecting the centers of the nearest conductive particles 2, and the repeat unit 5 is repeated with a predetermined regularity to cover one surface of the anisotropic conductive film. While there are no particular limitations on the arrangement shape of the conductive particles in the repeat unit 5 itself, if the conductive particles 2 in the repeat unit 5 are arranged so as to occupy part of a regular polygon, the arrangement of the conductive particles is easy to grasp, and it is therefore easy to determine whether any conductive particles are missing from the predetermined arrangement. Furthermore, if the arrangement of the conductive particles is easy to grasp, each task is easier during the manufacture of the anisotropic conductive film and in product inspections such as indentation inspections after connecting electronic components using the anisotropic conductive film, thereby enabling time savings and reductions in labor.

[0032] The lattice axis or arrangement axis of the conductive particles 2 may be parallel to or intersect with the longitudinal direction of the anisotropic conductive film, and can be determined depending on the width and pitch of the terminals to be connected. For example, in the case of an anisotropic conductive film for fine pitch applications, as shown in Fig. 1, the lattice axis L1 of the conductive particles 2 is oblique to the longitudinal direction of the anisotropic conductive film 1A, and the angle θ between the lattice axis L1 and the longitudinal direction of the terminals 10 to be connected by the anisotropic conductive film 1A (the transverse direction of the film) is preferably 6° to 84°, and more preferably 11° to 74°.

[0033] (conductive particles) The conductive particles 2 can be appropriately selected from those used in known anisotropic conductive films. Examples include metal particles such as nickel, copper, silver, gold, and palladium, and metal-coated resin particles in which the surface of resin particles such as polyamide and polybenzoguanamine is coated with a metal such as nickel. The size of the conductive particles to be arranged is preferably 1 μm or more and 30 μm or less, more preferably 1 μm or more and 10 μm or less, and even more preferably 2 μm or more and 6 μm or less.

[0034] The average particle size of the conductive particles 2 can be measured using an image or laser particle size distribution analyzer. The anisotropic conductive film may be observed in plan view and the particle size measured. In this case, preferably 200 or more particles, more preferably 500 or more particles, and even more preferably 1000 or more particles are measured.

[0035] The surfaces of the conductive particles 2 are preferably covered with an insulating coating or insulating particle treatment. Such a coating is selected so that it is difficult to peel off from the surface of the conductive particles 2 and does not cause problems in anisotropic connection. Furthermore, protrusions may be provided on the entire surface or part of the surface of the conductive particles 2. The height of the protrusions is preferably within 20% of the conductive particle diameter, and more preferably within 10%.

[0036] (Shortest distance between conductive particles) The shortest interparticle distance between conductive particles is preferably at least 0.5 times the average particle diameter of the conductive particles. If this distance is too short, contact between conductive particles is likely to cause short circuits. The upper limit of the distance between adjacent conductive particles can be determined depending on the bump shape and bump pitch. For example, if 10 or more conductive particles are to be captured, the distance should be less than 50 times the average particle diameter, preferably less than 40 times, and more preferably less than 30 times.

[0037] (Conductive particle number density) The number density of conductive particles is set to 50,000 particles / mm in order to reduce the manufacturing cost of the anisotropic conductive film. 2 Preferably less than 35,000 pieces / mm 2 Less than 30,000 pieces / mm is more preferable. 2 On the other hand, if the number density of the conductive particles is too low, the conductive particles may not be captured sufficiently by the terminal, which may cause a conduction failure. 2 More than 300 pieces / mm 2 More than 500 pieces / mm is preferable. 2 More preferably, 800 pieces / mm 2 The above is even more preferable.

[0038] (insulating resin binder) The insulating resin binder 3 can be appropriately selected from thermally polymerizable compositions, photopolymerizable compositions, photothermally polymerizable compositions, and the like, which are used as insulating resin binders in known anisotropic conductive films. Examples of the thermally polymerizable compositions include a thermally radically polymerizable resin composition containing an acrylate compound and a thermal radical polymerization initiator, a thermally cationic polymerizable resin composition containing an epoxy compound and a thermal cationic polymerization initiator, and a thermally anionic polymerizable resin composition containing an epoxy compound and a thermal anionic polymerization initiator. Examples of the photopolymerizable compositions include a photoradical polymerizable resin composition containing an acrylate compound and a photoradical polymerization initiator. Multiple polymerizable compositions may be used in combination, provided no particular problems arise. An example of a combination is a combination of a thermally cationic polymerizable composition and a thermally radical polymerizable composition.

[0039] The photopolymerization initiator may contain multiple types of photopolymerization initiators that react to light of different wavelengths, which allows different wavelengths to be used for photocuring the resin that constitutes the insulating resin layer and for photocuring the resin that bonds electronic components together during anisotropic connection during production of the anisotropic conductive film.

[0040] When the insulating resin binder 3 is formed using a photopolymerizable composition, all or part of the photopolymerizable compound contained in the insulating resin binder 3 can be photocured by photocuring during the production of the anisotropic conductive film. This photocuring maintains or fixes the arrangement of the conductive particles 2 in the insulating resin binder 3, and is expected to suppress short circuits and improve capture. Furthermore, by adjusting the photocuring conditions, the viscosity of the insulating resin layer during the production process of the anisotropic conductive film can be adjusted.

[0041] The amount of the photopolymerizable compound in the insulating resin binder 3 is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably less than 2% by mass, because if the amount of the photopolymerizable compound is too much, the thrust force applied during anisotropic conductive connection increases.

[0042] On the other hand, the thermally polymerizable composition contains a thermally polymerizable compound and a thermal polymerization initiator, but the thermally polymerizable compound may also function as a photopolymerizable compound. Furthermore, the thermally polymerizable composition may contain a photopolymerizable compound and a photopolymerization initiator in addition to the thermally polymerizable compound. Preferably, the thermally polymerizable composition contains a photopolymerizable compound and a photopolymerization initiator in addition to the thermally polymerizable compound. For example, a thermal cationic polymerization initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermally polymerizable compound, a photoradical initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. The insulating binder 3 may contain a cured product of these polymerizable compositions.

[0043] The acrylate compound used as the thermally or photopolymerizable compound may be a conventionally known thermally polymerizable (meth)acrylate monomer, such as a monofunctional (meth)acrylate monomer or a bifunctional or higher polyfunctional (meth)acrylate monomer.

[0044] Furthermore, the epoxy compound used as the polymerizable compound forms a three-dimensional network structure and imparts good heat resistance and adhesiveness, and it is preferable to use a solid epoxy resin and a liquid epoxy resin in combination. Here, the solid epoxy resin means an epoxy resin that is solid at room temperature. The liquid epoxy resin means an epoxy resin that is liquid at room temperature. The room temperature means a temperature range of 5 to 35°C as specified in JIS Z 8703. In the present invention, two or more epoxy compounds can be used in combination. An oxetane compound may also be used in addition to the epoxy compound.

[0045] The solid epoxy resin is not particularly limited as long as it is compatible with the liquid epoxy resin and is solid at room temperature, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, multifunctional epoxy resin, dicyclopentadiene type epoxy resin, novolac phenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, etc., and one of these can be used alone or two or more can be used in combination. Among these, it is preferable to use bisphenol A type epoxy resin.

[0046] The liquid epoxy resin is not particularly limited as long as it is liquid at room temperature, and examples thereof include bisphenol A epoxy resin, bisphenol F epoxy resin, novolac phenol epoxy resin, naphthalene epoxy resin, etc., and one of these may be used alone or two or more may be used in combination. In particular, from the viewpoint of the tackiness and flexibility of the film, it is preferable to use bisphenol A epoxy resin.

[0047] Among the thermal polymerization initiators, examples of the thermal radical polymerization initiator include organic peroxides, azo compounds, etc. In particular, organic peroxides that do not generate nitrogen, which causes bubbles, are preferably used.

[0048] If the amount of the thermal radical polymerization initiator used is too small, curing will be insufficient, and if it is too large, the product life will be shortened. Therefore, the amount is preferably 2 to 60 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the (meth)acrylate compound.

[0049] As the thermal cationic polymerization initiator, any known initiator for thermal cationic polymerization of epoxy compounds can be used. For example, iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, and the like that generate acids by heat can be used. In particular, aromatic sulfonium salts that exhibit good latency with respect to temperature can be preferably used.

[0050] If the amount of the thermal cationic polymerization initiator used is too small, curing will tend to be insufficient, while if it is too large, the product life will tend to be shortened. Therefore, the amount is preferably 2 to 60 parts by mass, more preferably 5 to 40 parts by mass, relative to 100 parts by mass of the epoxy compound.

[0051] As the anionic polymerization initiator, a commonly used known curing agent can be used. For example, organic acid dihydrazide, dicyandiamide, amine compound, polyamidoamine compound, cyanate ester compound, phenolic resin, acid anhydride, carboxylic acid, tertiary amine compound, imidazole, Lewis acid, Bronsted acid salt, polymercaptan-based curing agent, urea resin, melamine resin, isocyanate compound, blocked isocyanate compound, etc. can be mentioned, and one of these can be used alone or two or more can be used in combination. Among these, it is preferable to use a microcapsule-type latent curing agent in which an imidazole modified substance is used as a core and its surface is coated with polyurethane.

[0052] The thermally polymerizable composition preferably contains a film-forming resin. The film-forming resin corresponds to a high-molecular-weight resin, for example, having an average molecular weight of 10,000 or more, and from the viewpoint of film-forming properties, the average molecular weight is preferably about 10,000 to 80,000. Examples of film-forming resins include various resins such as phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, acrylic resin, polyimide resin, and butyral resin, which may be used alone or in combination of two or more. Among these, phenoxy resin is preferably used from the viewpoint of film formation state, connection reliability, etc.

[0053] The thermally polymerizable composition may contain an insulating filler to adjust the melt viscosity. Examples of such an insulating filler include silica powder and alumina powder. The insulating filler preferably has a particle size of 20 to 1000 nm, and the amount of the insulating filler is preferably 5 to 50 parts by mass per 100 parts by mass of the thermally polymerizable compound (photopolymerizable compound) such as an epoxy compound. Furthermore, the composition may contain other filling agents, softeners, accelerators, antioxidants, colorants (pigments, dyes), organic solvents, ion catchers, and the like, which are different from the insulating fillers described above.

[0054] If necessary, stress relaxation agents, silane coupling agents, inorganic fillers, etc. may be blended. Examples of stress relaxation agents include hydrogenated styrene-butadiene block copolymers and hydrogenated styrene-isoprene block copolymers. Examples of silane coupling agents include epoxy-based, methacryloxy-based, amino-based, vinyl-based, mercapto sulfide-based, and ureido-based agents. Examples of inorganic fillers include silica, talc, titanium oxide, calcium carbonate, and magnesium oxide.

[0055] The insulating resin binder 3 can be formed by applying a coating composition containing the above-mentioned resin to form a film, drying it, or further curing it, or by forming it into a film using a known method. The insulating resin binder 3 may also be obtained by laminating resin layers as needed. Furthermore, the insulating resin binder 3 is preferably formed on a release film such as a release-treated polyethylene terephthalate film.

[0056] (Viscosity of insulating resin binder) The minimum melt viscosity of the insulating resin binder 3 can be determined appropriately depending on the manufacturing method of the anisotropic conductive film. For example, when the manufacturing method of the anisotropic conductive film is to hold conductive particles in a predetermined arrangement on the surface of the insulating resin binder and then press the conductive particles into the insulating resin binder, the minimum melt viscosity of the insulating resin binder 3 is preferably 1100 Pa·s or more from the viewpoint of film formability. In particular, to enable film formation at 40 to 80°C, the viscosity of the insulating resin binder 3 at 60°C is preferably 3000 to 20000 Pa·s. Furthermore, as will be described later, in order to form recesses 3b around the exposed portions of the conductive particles 2 pressed into the insulating resin binder 3 as shown in Figures 5 and 6, or recesses 3c directly above the conductive particles 2 pressed into the insulating resin binder 3 as shown in Figure 7, the minimum melt viscosity of the insulating resin binder 3 should be 1500 Pa·s or higher, preferably 2000 Pa·s or higher, more preferably 3000 to 15,000 Pa·s, and even more preferably 3000 to 10,000 Pa·s. This minimum melt viscosity can be determined, for example, using a rotational rheometer (manufactured by TA Instruments) at a heating rate of 10°C / min, a constant measurement pressure of 5 g, and an 8 mm diameter measurement plate. Furthermore, when the step of pressing the conductive particles 2 into the insulating resin binder 3 is performed at 40 to 80°C, the viscosity of the insulating resin binder 3 at 60°C is preferably 3000 to 20,000 Pa·s in order to form recesses 3b or 3c, as described above. This measurement is carried out in the same manner as for the minimum melt viscosity, and the value at a temperature of 60°C is extracted and determined.

[0057] By increasing the viscosity of the resin constituting the insulating resin binder 3 as described above, when the anisotropic conductive film is used and the conductive particles 2 are sandwiched between opposing connection objects such as electronic components and heated and pressurized, the conductive particles 2 in the anisotropic conductive film can be prevented from being washed away by the flow of the molten insulating resin binder 3. Furthermore, when the amount of resin around or directly above the conductive particles, as in the recesses 3b and 3c, is essentially zero or reduced compared to the surrounding area, the pressing force applied to the conductive particles from the connecting tool is easily transmitted, so the conductive particles can be well sandwiched between the terminals, which is expected to improve the conductivity characteristics and the ability to capture conductive particles.

[0058] (Thickness of insulating resin binder) The thickness La of the insulating resin binder 3 is preferably 1 μm or more and 60 μm or less, more preferably 1 μm or more and 30 μm or less, and even more preferably 2 μm or more and 15 μm or less. Furthermore, in relation to the thickness La of the insulating resin binder 3 and the average particle diameter D of the conductive particles 2, the ratio (La / D) thereof is preferably 0.6 to 10. If the thickness La of the insulating resin binder 3 is too large, the conductive particles are more likely to be displaced during anisotropic conductive connection, and the capture of the conductive particles in the terminals is reduced. This tendency becomes more pronounced when La / D exceeds 10. Therefore, La / D is more preferably 8 or less, and even more preferably 6 or less. Conversely, if the thickness La of the insulating resin binder 3 is too small, resulting in La / D being less than 0.6, it becomes difficult for the insulating resin binder 3 to maintain the conductive particles in a predetermined particle dispersion state or a predetermined arrangement. In particular, when the terminal to be connected is a high density COG, the ratio (La / D) of the layer thickness La of the insulating adhesive layer 4 to the particle diameter D of the conductive particles 2 is preferably 0.8-2.

[0059] (Embedding of conductive particles in insulating resin binder) Although there are no particular limitations on the embedding state of the conductive particles 2 in the insulating resin binder 3, when an anisotropic conductive film is sandwiched between opposing components and heated and pressurized to form an anisotropic conductive connection, it is preferable that the conductive particles 2 are partially exposed from the insulating resin binder 3, and that a depression 3b is formed around the exposed portion of the conductive particle 2 relative to a tangent plane 3p of the surface 3a of the insulating resin binder in the center between adjacent conductive particles 2, as shown in Figures 5 and 6, or that a depression 3c is formed relative to the tangent plane 3p in the insulating resin binder portion directly above the conductive particle 2 pressed into the insulating resin binder 3, as shown in Figure 7, so that an undulation is present on the surface of the insulating resin binder 3 directly above the conductive particle 2. When the conductive particles 2 are sandwiched between the electrodes of opposing electronic components and heated and pressurized, the conductive particles 2 are flattened. However, the presence of the depression 3b shown in Figure 5 reduces the resistance that the conductive particles 2 experience from the insulating resin binder 3 compared to when the depression 3b is absent. This makes it easier for the conductive particles 2 to be sandwiched between the opposing electrodes, improving electrical conductivity. Furthermore, because the resin that makes up the insulating resin binder 3 has depressions 3c (FIG. 7) formed on the surface of the resin directly above the conductive particles 2, pressure during heating and pressurization is more likely to be concentrated on the conductive particles 2 than in the absence of depressions 3c, making it easier for the conductive particles 2 to be sandwiched between the electrodes and improving electrical conductivity.

[0060] In order to easily obtain the effects of the above-mentioned recesses 3b and 3c, the ratio (Le / D) of the maximum depth Le of the recess 3b (Figures 5 and 6) around the exposed portions of the conductive particles 2 to the average particle diameter D of the conductive particles 2 is preferably less than 50%, more preferably less than 30%, and even more preferably 20 to 25%; the ratio (Ld / D) of the maximum diameter Ld of the recess 3b (Figures 5 and 6) around the exposed portions of the conductive particles 2 to the average particle diameter D of the conductive particles 2 is preferably 150% or less, more preferably 100 to 130%; and the ratio (Lf / D) of the maximum depth Lf of the recess 3c (Figure 7) in the resin directly above the conductive particles 2 to the average particle diameter D of the conductive particles 3 is greater than 0, preferably less than 10%, and more preferably 5% or less.

[0061] The diameter Lc of the exposed portion of the conductive particle 2 can be equal to or less than the average particle size D of the conductive particle 2, and may be exposed at one point at the top 2t of the conductive particle 2, or the conductive particle 2 may be completely embedded in the insulating resin binder 3, with the diameter Lc being zero. When embedding the filler P in the insulating resin layer by pressing the filler P into the insulating resin layer, it is preferable to set the diameter Lc to within 15% from the viewpoint of ease of adjusting the position of the filler.

[0062] (Position of conductive particles in the thickness direction of the insulating resin binder) In order to easily obtain the effect of the recess 3b described above, it is preferable that the ratio (Lb / D) (hereinafter referred to as the embedding rate) of the distance Lb from the tangential plane 3p to the deepest part of the conductive particle 2 to the average particle size D of the conductive particle 2 is 60% or more and 105% or less.

[0063] (insulating adhesive layer) In the anisotropic conductive film of the present invention, an insulating adhesive layer 4 may be laminated on the insulating resin binder 3 in which the conductive particles 2 are arranged.

[0064] When the insulating resin binder 3 has the above-mentioned recesses 3b formed therein, the insulating adhesive layer 4 may be laminated on the side of the insulating resin binder 3 on which the recesses 3b are formed, as in the anisotropic conductive film 1d shown in FIG. 8, or on the side opposite to the side on which the recesses 3b are formed, as in the anisotropic conductive film 1e shown in FIG. 9. The same applies when the insulating resin binder 3 has recesses 3c formed therein. By laminating the insulating adhesive layer 4, when electronic components are anisotropically conductively connected using the anisotropic conductive film, the spaces formed by the electrodes and bumps of the electronic components can be filled, thereby improving adhesion.

[0065] When the insulating adhesive layer 4 is laminated on the insulating resin binder 3, it is preferable that the insulating adhesive layer 4 be on the side of the electronic component, such as an IC chip, that is pressed by the tool (in other words, the insulating resin binder 3 be on the side of the electronic component, such as a substrate, that is placed on the stage), regardless of whether the insulating adhesive layer 4 is on the surface on which the recesses 3b and 3c are formed. This makes it possible to avoid unintended movement of the conductive particles and improve capture properties.

[0066] The insulating adhesive layer 4 can be the same as those used as insulating adhesive layers in known anisotropic conductive films, or it can be a resin similar to the insulating resin binder 3 described above, but with a lower viscosity. The greater the difference in minimum melt viscosity between the insulating adhesive layer 4 and the insulating resin binder 3, the easier it is for the insulating adhesive layer 4 to fill the spaces formed by the electrodes and bumps of electronic components, thereby improving the adhesion between electronic components. Furthermore, the greater this difference, the smaller the amount of migration of the resin constituting the insulating resin binder 3 during anisotropic conductive connection, thereby improving the ability to capture conductive particles in the terminals. In practice, the minimum melt viscosity ratio between the insulating adhesive layer 4 and the insulating resin binder 3 is preferably 2 or greater, more preferably 5 or greater, and even more preferably 8 or greater. On the other hand, if this ratio is too large, resin overflow or blocking may occur when a long anisotropic conductive film is wound; therefore, in practice, a ratio of 15 or less is preferred. More specifically, the preferred minimum melt viscosity of the insulating adhesive layer 4 satisfies the above ratio and is 3000 Pa·s or less, more preferably 2000 Pa·s or less, and particularly 100 to 2000 Pa·s.

[0067] The insulating adhesive layer 4 can be formed by applying a coating composition containing the same resin as the resin that forms the insulating resin binder 3, drying it, further hardening it, or by forming it into a film using a known method.

[0068] The thickness of the insulating adhesive layer 4 is not particularly limited, but is preferably 4 to 20 μm, or preferably 1 to 8 times the diameter of the conductive particles.

[0069] Furthermore, the minimum melt viscosity of the entire laminated anisotropic conductive film, which includes the insulating resin binder 3 and the insulating adhesive layer 4, depends on the thickness ratio of the insulating resin binder 3 to the insulating adhesive layer 4, but in practice it may be 8000 Pa·s or less, or may be 200 to 7000 Pa·s to facilitate filling between the bumps, and is preferably 200 to 4000 Pa·s.

[0070] (Third insulating resin layer) A third insulating resin layer may be provided on the opposite side of the insulating adhesive layer 4 and the insulating resin binder 3. For example, the third insulating resin layer may function as a tack layer. Like the insulating adhesive layer 4, the third insulating resin layer may be provided to fill spaces formed by electrodes or bumps of the electronic component.

[0071] The resin composition, viscosity, and thickness of the third insulating resin layer may be the same as or different from those of the insulating adhesive layer 4. The minimum melt viscosity of the anisotropic conductive film comprising the insulating resin binder 3, the insulating adhesive layer 4, and the third insulating resin layer is not particularly limited, but may be 8000 Pa·s or less, 200 to 7000 Pa·s, or 200 to 4000 Pa·s.

[0072] Furthermore, insulating fillers such as silica fine particles, alumina, and aluminum hydroxide may be added as needed not only to the insulating resin binder 3 but also to the insulating adhesive layer 4. The amount of insulating filler blended is preferably 3 to 40 parts by mass per 100 parts by mass of the resin constituting those layers. This makes it possible to prevent unnecessary movement of conductive particles in the molten resin even if the anisotropic conductive film melts during anisotropic conductive connection.

[0073] <Method for manufacturing anisotropic conductive film> (Summary of manufacturing method) In the present invention, first, a wide-width raw sheet of an anisotropic conductive film in which conductive particles are regularly arranged in an insulating binder is obtained or produced. Next, the raw sheet of anisotropic conductive film is examined for gaps in the regular arrangement of conductive particles. To prevent non-standard areas, where a predetermined number or more of conductive particles are continuously missing from the regular arrangement, from being used as areas responsible for connections, the wide-width raw sheet is cut into anisotropic conductive films of a predetermined width so as to exclude the areas including the non-standard areas (first embodiment). Alternatively, the wide-width raw sheet is cut lengthwise to a predetermined width so that the non-standard areas are positioned at the intended positions in the short direction of the film (second embodiment). Furthermore, in the first embodiment, an anisotropic conductive film after removing the non-standard areas (i.e., the remaining anisotropic conductive films or separate anisotropic conductive films after removing the non-standard areas) may be joined together to produce an anisotropic conductive film of 5 m or more in length.

[0074] Here, there are no particular limitations on the method for producing the initial anisotropic conductive film before removing the above-mentioned regions. For example, a transfer mold for arranging conductive particles in a predetermined arrangement is manufactured, the conductive particles are filled into the recesses of the transfer mold, and an insulating resin binder 3 formed on a release film is placed on top of it, and pressure is applied to press the conductive particles 2 into the insulating resin binder 3, thereby transferring the conductive particles 2 to the insulating resin binder 3. Alternatively, an insulating adhesive layer 4 is further laminated on the conductive particles 2. In this way, an anisotropic conductive film can be obtained.

[0075] Alternatively, an anisotropic conductive film may be produced by filling the recesses of a transfer mold with conductive particles, covering them with an insulating resin binder, transferring the conductive particles from the transfer mold to the surface of the insulating resin binder, and pressing the conductive particles on the insulating resin binder into the insulating resin binder. The amount of conductive particle embedment (Lb) can be adjusted by the pressing force, temperature, etc. during this pressing. The shape and depth of the recesses 3b and 3c can be adjusted by the viscosity of the insulating resin binder, the pressing speed, temperature, etc. during pressing. For example, when manufacturing an anisotropic conductive film 1a having the recesses 3b shown in Fig. 5 on the surface of the insulating resin binder, or an anisotropic conductive film 1c having the recesses 3c shown in Fig. 7, the lower limit of the viscosity of the insulating resin binder at 60°C is preferably 3000 Pa·s or more, more preferably 4000 Pa·s or more, and even more preferably 4500 Pa·s or more, depending on the shape and depth of the recesses, and the upper limit is preferably 20000 Pa·s or less, more preferably 15000 Pa·s or less, and even more preferably 10000 Pa·s or less. The temperature during pressing is 40 to 80°C, and more preferably 50 to 60°C.

[0076] As the transfer mold, in addition to the one in which conductive particles are filled in the recesses, a mold in which a slight adhesive is applied to the top surfaces of the protrusions so that the conductive particles adhere to the top surfaces may be used. These transfer molds can be manufactured using known techniques such as machining, photolithography, and printing. As a method for arranging the conductive particles in a predetermined arrangement, a method using a biaxially stretched film may be used instead of the method using the transfer side.

[0077] (Handling of missing areas) In a first aspect of the method for producing an anisotropic conductive film of the present invention, whether the anisotropic conductive film is used for a connection structure in which the individual bump areas are relatively small (such as a COG, which is an example of a connection structure in which the terminals to be connected are spaced apart) or a connection structure in which the individual bump areas are relatively large (such as a FOG, which is an example of a connection structure in which the long side of the effective connection area is the same as the film width and the terminals are not spaced apart), in which the conductive particles are regularly arranged in a planar view, preferably in which the conductive particles are regularly spaced apart in a planar view, non-standard areas where a predetermined number of consecutive conductive particle missing points are removed from the region in which the conductive particles are regularly arranged (regularly arranged region). In other words, regions in which the missing points are merely scattered within an area that does not cause problems in the stability of electrical connection after connection are considered to be within the standard region and are not subject to removal. The range within which this problem does not occur varies depending on the object to be connected, but as an example, when an anisotropic conductive film is used for FOG, even if 1 to 20 conductive particles, or in some cases 1 to 209 conductive particles are missing in a row, there is little problem with the stability of conduction. Here, the number 209, which is the number of consecutive missing conductive particles, has the following meaning. That is, under the anisotropic conductive connection conditions for FOG, where the width of the anisotropic conductive film is 2 mm and the width of the terminal to be connected is 200 μm, which is generally considered to have a large connection area (connection area 0.4 m m 2 ), when conducting particles are arranged in a 15 × 15 square lattice, ideally 225 conducting particles would have a connection area of ​​0.4 m m 2 Even if 209 conductive particles are removed, the connection area is 0.4 m m 2This means that a minimum of 16 conductive particles are present in the terminal area. Here, the number of conductive particles to be captured (16) is set as an intermediate value between the lower limits of the preferred number of captured particles (11 and 20, as described below). Therefore, it is considered a suitable value for finding conditions that facilitate stable conduction. Thus, if the number of captured conductive particles (16 in this case) is greater than the number of conductive particles on the lattice arrangement axis (as described above, the number of conductive particles on the lattice arrangement axis in this case is 15), this means that the number of conductive particles captured in one terminal is greater than the total number of lattice axes in a certain direction, and thus the captured conductive particles are present on at least two arrangement axes in the same direction. Thus, if conductive particles arranged on at least two lattice axes are captured, it is expected that the positions of the conductive particles captured in the terminal are spaced apart to a certain extent, allowing for comparison of the balance of the pressing force. In other words, the conditions for determining whether the conductive particle pressing during connection is successful are met. When used in a COG, problems with conductivity stability are unlikely to occur if the number of consecutive missing pieces is 1 to 20, and problems are even less likely to occur if the number is 15 or less, and particularly 10 or less.

[0078] It should be noted that even within the standard range, there may be acceptable gaps that do not impair connection. The size of such acceptable gaps can be determined based on the spacing between terminals. This is a method other than the aforementioned determination based on the number of consecutive gaps. For example, it is preferable that gaps in the longitudinal direction of the film (the width direction of the terminals) be less than the sum of the spacing between terminals (i.e., that gaps do not span two terminals). Furthermore, it is preferable that gaps in the transverse direction of the film (the longitudinal direction of the terminals) be spaced apart by a distance greater than 50% of the terminal length. This ensures that captureable conductive particles are present in an area that is at least less than 50% of the terminal length. With gaps like this, it is expected that the conductivity performance will be acceptable in a typical anisotropic connection. When considering such gaps, the size of the gaps can be considered as a rectangle defined by the longest distance between conductive particles in directions parallel to both the longitudinal and transverse directions of the film. Considering this, the allowable size of the missing portion when applied to fine-pitch terminals such as COG is, for example, preferably 80 μm or less in the longitudinal direction of the film (terminal width direction), more preferably 30 μm or less, and even more preferably 10 μm or less. Furthermore, since it is desirable that a region captured by the film in the transverse direction of the terminal remains at 50% or more of the terminal length, for example, the allowable size is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. Furthermore, for FOG with wide terminal widths, the allowable size is preferably 400 μm or less, more preferably 200 μm or less in the longitudinal direction of the film (terminal width direction). The transverse direction of the film is the effective connection area, so the allowable size is 50% or less, preferably 30% or less, of the transverse direction of the film. Depending on the terminal layout, the above values ​​may be combined as appropriate. This is because the present invention is not limited to general COG or FOG.

[0079] As shown in Figure 1, if the gaps 2X are not continuous and exist independently, or if the gaps 2X are connected in less than a predetermined number, they are considered scattered. In contrast, if there is a portion 2Y where there are more than a predetermined number of continuous gaps 2X and this is to be removed as an irregular portion, the anisotropic conductive film is cut in the longitudinal direction, and a strip-shaped region R including this portion 2Y is removed. Note that in Figure 1, an area with three consecutive gaps is considered an irregular portion, but this number is merely an example.

[0080] The presence or absence of such voids can be observed using an imaging device such as an optical microscope, a metallurgical microscope, or a CCD camera. Furthermore, the dispersion state of the conductive particles in the anisotropic conductive film 1A can be inspected using a combination of an imaging device and an image analysis and processing system (e.g., WinROOF, Mitani Corporation), allowing the voids to be discovered and their locations to be identified. For example, an imaging device with a maximum output pixel count (H) × (V) of 648 × 494 and a frame rate of 30 to 60 fps can be used.

[0081] For an anisotropic conductive film for connection structures (such as FOGs) with relatively large bump areas, it is preferable to cut the raw sheet so that there are 10 or more conductive particles in any region S of the anisotropic conductive film 1C that is 200 μm long in the longitudinal direction of the anisotropic conductive film across the entire width W, as shown in Figure 3. In other words, the anisotropic conductive film has a total width W such that there are 10 or more conductive particles in any position within a 200 μm long range across the entire length of the anisotropic conductive film. This is because the maximum bump width in a typical FOG connection is approximately 200 μm. Note that the bump length (or tool width) in a typical FOG connection is 0.3 to 4 mm, so the total width W of the anisotropic conductive film after cutting is preferably 4 mm or less.

[0082] The number of conductive particles present in region S is preferably 11 or more, and even more preferably 20 or more, in order to increase the number of conductive particles captured by the terminals to improve connection reliability. There is no particular upper limit. However, if the number of conductive particles present in region S is excessively large, resulting in too many conductive particles being captured by the terminals during anisotropic conductive connection, the thrust force required for the pressing jig used in the anisotropic conductive connection will also increase excessively. In this case, there is a concern that the degree of pressing will be excessively different between the individual anisotropic connection structures obtained by continuous anisotropic connection. Therefore, the number of conductive particles present in region S is preferably 50 or less, more preferably 40 or less, and even more preferably 35 or less.

[0083] On the other hand, in a second aspect of the method for manufacturing an anisotropic conductive film of the present invention, in the case of an anisotropic conductive film for a connection structure (such as a COG) in which the area of ​​each bump is relatively small, the original sheet is cut so that there are no irregular areas at the short end 1P of the anisotropic conductive film 1A, where there are a predetermined number or more consecutive areas 2X where conductive particles are missing from the regular arrangement, and it is possible to ensure that even if there are missing conductive particles at the end 1P of the anisotropic conductive film after cutting, there are no irregular areas, and preferably the conductive particles 2 are present in a predetermined arrangement.

[0084] Here, the width of the end 1P in the lateral direction of the anisotropic conductive film 1A is preferably within 20%, more preferably within 30%, of the lateral width of the anisotropic conductive film 1A. This is because, when connecting electronic components using an anisotropic conductive film, the terminal row of the electronic component is usually located in a strip-shaped region within 20%, more preferably within 30%, of the lateral width from the edge extending in the longitudinal direction of the anisotropic conductive film. Note that the size of this end 1P may differ between the left and right ends depending on the layout of the terminals of the electronic component to be connected.

[0085] As shown in FIG. 4, when bumps (terminals) 10 are arranged in two rows on an electronic component 12, such as an IC chip, to be connected by COG, and an anisotropic conductive film 1 used for this connection has irregularities where a predetermined number or more of conductive particles are missing in a region where conductive particles are regularly arranged (regularly arranged region), if an irregular region Q without irregularities is formed with a predetermined width in the short direction of the anisotropic conductive film 1 and a predetermined length in the long direction of the anisotropic conductive film 1, the irregular region Q is aligned with the terminal row 11. In other words, the region R containing irregularities in the anisotropic conductive film 1 is aligned with the region between the two terminal rows 11 (i.e., the region where no terminals to be connected exist), and opposing electronic components 12 are anisotropically conductively connected by the anisotropic conductive film 1. The present invention also encompasses connection structures anisotropically conductively connected by such alignment. In FIG. 4, the distance is the distance from the end of the electronic component 12 to the inner edge of the bump 10. It is preferable that this distance overlaps with the width of the standard area Q. As for the alignment method, in the case of COG, when laminating the film to the glass, the alignment may be performed by moving the stage on which the glass is placed, or by moving the film itself. This alignment method is not limited to COG, but can also be applied to the manufacture of FOG and other connection structures. The present invention includes a manufacturing method of a connection structure that includes such steps.

[0086] More specifically, the longitudinal length L10 of each terminal 10 is typically 30 to 300 μm, and the distance L11 between two terminal rows 11 ranges from 100 to 200 μm for small electronic components such as IC chips with relatively small external dimensions when there are multiple rows of bumps (for example, a staggered arrangement of three rows), and from 1000 to 2000 μm for large electronic components such as IC chips with relatively long external dimensions. Therefore, in the anisotropic conductive film 1, if the width LR of the region R including the non-standard portion is within the distance L11 between adjacent terminal rows 11, and the width LQ of the standard region Q is equal to the longitudinal length L10 of the terminals 10, no problem will arise in COG connection. Also, even if the width LR of the anisotropic conductive film region R exceeds the distance L11 between the terminal rows and the region R partially overlaps with the terminal row 11, there will be no practical problem as long as the number of conductive particles captured by each terminal 10 through the anisotropic conductive connection is preferably 10 or more, more preferably 13 or more. For example, if the size of the terminals 10 is 100 μm × 20 μm, the interval L11 between the terminal rows 11 is 1000 μm, and the number density of conductive particles in the standard region Q of the anisotropic conductive film 1 is 32,000 particles / mm 2 In this case, even if the region R of the anisotropic conductive film overlaps the terminal 10, as long as the overlap width is within 50% of the length L10 of the terminal 10, COG connection can be performed without any practical problems.

[0087] (Cutting anisotropic conductive film) In the method for producing an anisotropic conductive film of the present invention, in order to increase the productivity of the anisotropic conductive film, a long anisotropic conductive film is produced with a certain width, and then, using the inspection method described above, any missing conductive particles are checked, preferably also any defects such as agglomerations, and the anisotropic conductive film is cut so that these are not included in the anisotropic conductive film of the specified width, or, alternatively, the anisotropic conductive film is cut to a specified width so that the missing portions, agglomerations, and other defects are included within the anisotropic conductive film and their positions are the intended positions in the short direction of the anisotropic conductive film, thereby producing an anisotropic conductive film in which missing portions are substantially not a problem. In this anisotropic conductive film production process, marking may be used to record any defects.

[0088] (Anisotropic conductive film joining) In the method for manufacturing an anisotropic conductive film of the present invention, the remaining anisotropic conductive film after cutting out the area containing the specified missing portion can be joined together to provide an anisotropic conductive film in which the missing portions are not a problem in practical use, even if they are present.

[0089] According to the present invention, an anisotropic conductive film can be obtained inexpensively, which has no more than a predetermined number of consecutive missing particles in the longitudinal direction over the entire length of a long anisotropic conductive film wound on a reel and having a length of 5 m or more and 5000 m or less.In particular, for COG, an anisotropic conductive film can be obtained, which has no missing conductive particles at the end 1P of the film's short width over the entire length of a long anisotropic conductive film having a length of 5 m or more and 5000 m or less.

[0090] <Connection structure> The anisotropically conductive film of the present invention is preferably used for anisotropically conductively connecting a first electronic component such as an FPC, IC chip, or IC module to a second electronic component such as an FPC, rigid substrate, ceramic substrate, glass substrate, or plastic substrate by heat or light. It is also possible to stack IC chips or IC modules to anisotropically conductively connect the first electronic components to each other. The connection structure obtained in this manner is also part of the present invention.

[0091] A preferred method for connecting electronic components using an anisotropic conductive film is to temporarily attach the interface of the anisotropic conductive film on the side of the film thickness where the conductive particles are closest to a second electronic component such as a wiring board, mount a first electronic component such as an IC chip on the temporarily attached anisotropic conductive film, and then thermocompress the first electronic component. Photocuring can also be used for connection. For efficiency reasons, it is preferable to align the longitudinal direction of the terminals 10 of the electronic component with the transverse direction of the anisotropic conductive films 1A and 1B. [Example]

[0092] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. It is not limited thereto.

[0093] <Fabrication of Transfer Master Disk for COG> First, the master disk used in the examples was prepared as follows. That is, a nickel plate with a thickness of 2 mm was prepared, and cylindrical convex portions (outer diameter 4 μm, height 4 μm, center-to-center distance 6 μm) were formed in a hexagonal lattice pattern in a 50 cm square area thereof, and the surface density of the convex portions was 32,000 pieces / mm 2 to obtain a transfer master disk.

[0094] (Fabrication of Film-like Master Disk) Next, a polyethylene terephthalate base film with a width of 50 cm and a thickness of 50 μm was prepared, and a photocurable resin composition containing 100 parts by mass of an acrylate resin (M208, Toagosei Co., Ltd.) and 2 parts by mass of a photopolymerization initiator (IRGACURE184, BASF Japan Ltd.) was applied thereto so that the film thickness became 30 μm.

[0095] With respect to the obtained photocurable resin composition film, a nickel transfer master disk was pressed from its convex surface, and light irradiation was performed from the base film side with a high-pressure mercury lamp (1000 mJ), whereby a photocured resin layer in which the convex portions of the transfer master disk were transferred as concave portions was formed. By continuously repeating this operation while aligning in the longitudinal direction of the base film, a film-like master disk of about 10 m in which the convex portions of the transfer master disk were transferred as concave portions was obtained. In the obtained film-like master disk, the concave portions corresponding to the convex portion pattern of the transfer master disk were arranged in a hexagonal lattice.

[0096] 1000 locations were selected in an arbitrary 1 mm 2 region of the obtained film-like master disk, and the number of concave portions in each region was measured with an optical microscope. Then, the surface density of the concave portions was calculated by dividing the total number of the measured numbers in each region by the total area of the region. As a result, the surface density of the concave portions was the same as that of the convex portion pattern of the transfer master disk, 32,000 pieces / mm 2 was obtained.

[0097] <Creation of Anisotropic Conductive Film Compatible with COG> (Filling of Conductive Particles into Film - like Substrate)

[0098] As conductive particles, metal - coated resin particles (Sekisui Chemical Co., Ltd., AUL703, average particle diameter 3 μm) were prepared. These conductive particles were sprayed onto the surface of the film - like substrate multiple times, and then the conductive particles were wiped with a cloth to fill the concave portions of the film - like substrate cut to 30 cm in the length direction with conductive particles. The cutting locations are a total of 5 locations including the starting point, the ending point, and 3 intermediate locations between the starting and ending points. Here, in order to have conductive particles that are not filled into this resin mold, by adjusting the number of conductive particles to be sprayed, the number of spraying times, etc., a region where the conductive particles are in a predetermined missing state was obtained.

[0099] (Creation of Film for Insulating Resin Layer and Film for Second Insulating Resin Layer) To determine a resin formulation suitable for COG, resin compositions with the formulations shown in Table 1 were mixed, applied to a peeled PET film, and dried to prepare a film for insulating resin layer (thickness 4 μm) from insulating binders A1 - A4 and a film for second insulating resin layer (thickness 14 μm) from insulating binder B, each with a size of 20×30 cm.

[0100]

Table 1

[0101] (Transfer of Conductive Particles to Insulating Resin Layer) The above-mentioned insulating resin layer film was placed on a cut film master filled with conductive particles under predetermined conditions, with the longitudinal length of the film aligned and the width aligned to include the center of the film master. The conductive particles were transferred by pressing at 60°C and 0.5 MPa. The insulating resin layer film was then peeled off from the film master, and the conductive particles on the insulating resin layer film were pressed into the insulating resin layer film by applying pressure (pressing conditions: 60-70°C, 0.5 MPa). A second insulating resin layer film was then laminated on the conductive particle transfer surface. This process was repeated at five points on the cut film master to produce anisotropic conductive films (ACF1-ACF4) with conductive particles embedded as shown in Figure 8. In this case, the embedding of the conductive particles was controlled by the pressing conditions. Five film-like masters prepared in this way were cut into 30 cm pieces along the longitudinal direction and the embedded state of the conductive particles was observed as a set. As shown in Table 2, depressions were observed around or directly above the exposed portions of the embedded conductive particles in all of the sets. Furthermore, ACF4 was unable to maintain its film shape after the conductive particles were pressed into it. Therefore, it was determined that ACFs 1 to 3 could be used for COG. The embedded state of the conductive particles was confirmed before the insulating binder B was layered. Furthermore, for ACFs 1 to 3, images acquired with a CCD image sensor were observed for conductive particle voids using image analysis software (WinROOF, Mitani Corporation). The results showed that there were multiple voids consisting of five or fewer consecutive particles along the length of the film (maximum interparticle distance within 33 μm, less than the sum of the bump width and interbump gap, which will be described later, 38 μm) and seven or fewer particles along the width (maximum interparticle distance within 45 μm). This rectangular area of ​​33 μm in the film length direction and 38 μm in the film width direction can be considered an acceptable void. Therefore, voids smaller than this are recognized as acceptable voids. Note that the voids in the width direction were spaced apart by a bump length of 50 μm or more.

[0102] [Table 2]

[0103] (Production of anisotropic conductive film for COG, taking into consideration the loss of conductive particles) Next, the film was slit to a width of 1.8 mm so that the "state of conductive particle omission" (see Figures 4 and 10: LQ [μm], LR [μm], LQ / W [%], LR / W [%]) for Examples 1 to 4 and Comparative Example 1 shown in Table 3 was reflected. If this was not possible, the amount of conductive particles dispersed was adjusted, and the preparation procedure for ACF1 to ACF3 was repeated for each Example and Comparative Example to produce three types of anisotropic conductive films. The anisotropic conductive films of each Example and Comparative Example were slit to a width of 1.8 mm so that the LR (the width of the non-standard area (area where no conductive particles exist)) was located in the center of the film. Here, the non-standard area includes a rectangular area where no conductive particles exist, with one side larger than the allowable rectangular area of ​​omission measuring 33 μm in the length direction of the film and 38 μm in the width direction of the film, or includes an area where the above-mentioned allowable rectangular area of ​​omission is closer by less than 50 μm in the width direction.

[0104] [Table 3]

[0105] <Evaluation 1 (COG)> The conductive properties (initial conductivity and conductive reliability) of the connection structures obtained by COG connection using the three types of anisotropic conductive films produced in Examples 1 to 4 and Comparative Example 1 were tested and evaluated as follows.

[0106] (Initial conductivity) The following evaluation IC (see Figure 10) and glass substrate were used as the electronic components to be connected on a COG. The anisotropic conductive film to be evaluated was sandwiched between the evaluation IC and the glass substrate and heated and pressurized (180°C, 60 MPa, 5 seconds) to obtain each connection for evaluation. The longitudinal direction of the anisotropic conductive film was aligned with the transverse direction of the bumps, and the pair of standard regions of the anisotropic conductive film were bonded to both ends of the transverse direction of the IC chip. The conduction resistance of the resulting connection structure was measured using a digital multimeter (34401A, Agilent Technologies) using the four-terminal method (JIS K7194). For practical purposes, a resistance of 2 Ω or less is desirable. (Continuity reliability) The connection structure used to measure the initial conduction resistance was placed in a thermostatic chamber at 85°C and 85% humidity for 500 hours, and then the conduction resistance was measured again. In practice, a value of 5Ω or less is desirable.

[0107] (Evaluation IC) IC dimensions: 1.6mm (width) x 30.0mm (length) x 0.2mm (thickness) Gold bump: 15 μm (height) × 20 μm (width) × 100 μm (length) (The gap between the bumps is 18 μm, and 1000 gold bumps are arranged at each end of the IC's outer width along the IC's outer length. The distance between the gold bumps is 1000 μm.)

[0108] FIG. 10 is a plan view of the evaluation IC 100 as seen from the bump-forming surface side. 101 denotes the bumps, and G denotes the gap between the bumps. 102 denotes the distance between the bump arrangements. Areas A and B enclosed by dotted lines correspond to the standard areas of the anisotropic conductive film, and area C sandwiched between them corresponds to the non-standard area of ​​the anisotropic conductive film (the area where no conductive particles are present). Furthermore, V denotes the distance between the short edge of the IC chip and the end of the bump.

[0109] (glass substrate) Glass material: Corning 1737F External size 30mm×50mm Thickness 0.5mm ITO wiring for terminals

[0110] (Evaluation criteria) For the connection structure used in the measurement, when the initial conduction resistance is 2 Ω or less at all terminals and the conduction resistance after the conduction reliability test is 5 Ω or less, it is evaluated as "good", and otherwise (if there is even one bump outside the above range), it is evaluated as "bad". The obtained results are shown in Table 3.

[0111] As shown in Table 3, the connection structures fabricated using three different types of anisotropic conductive films in Examples 1 to 4 had good conduction characteristics. However, in the case of Comparative Example 1, the conduction characteristics were evaluated as poor because the area within the standard was too small.

[0112] It was found that even if there is a missing area on a part of the terminal, there is no practical problem as long as there are 10 or more, preferably 13 or more, conductive particles captured by the terminal. The missing area may cover the terminal arrangement, but it was also found that this varies depending on the terminal area and can be adjusted as appropriate (Example 4). In view of the above examples, it was found that the ratio of the area within the standard of the film width should be 13% or more, preferably 20% or more, and more preferably 33% or more.

[0113] <Fabrication of a transfer body master for FOG, a film-like master for FOG, and an anisotropic conductive film compatible with FOG> By repeating the process of preparing anisotropic conductive films for COG, except for using the binders listed in Table 4 instead of the insulating resin binders listed in Table 1 and selecting conditions that would result in the conductive particles being in a predetermined loose state, we produced FOG transfer masters, FOG film masters, and anisotropic conductive films (ACF5 to ACF8) with conductive particles embedded in the state shown in Figure 8. In this case, the embedded state of the conductive particles was controlled by the pressing conditions. As a result, depressions were observed around the exposed portions of the embedded conductive particles or directly above the embedded conductive particles, as shown in Table 5. This was confirmed before the insulating binder D was layered. Note that ACF8 was unable to maintain its film shape when the conductive particles were pressed into it. Therefore, it was found that ACF5 to ACF7 can be used for FOG.

[0114] Furthermore, for ACF5 to 7, images acquired by a CCD image sensor were observed and confirmed for the presence of missing conductive particles using image analysis software (WinROOF, Mitani Corporation). As a result, one sample (Example 5) had a missing state where 10 or more conductive particles were always present within 200 μm in the longitudinal direction of the film (terminal width direction), and another sample (Comparative Example 2) had a missing state where only 1 to 2 conductive particles were present.

[0115] [Table 4]

[0116] [Table 5]

[0117] (Production of anisotropic conductive film for FOG, taking into consideration the loss of conductive particles) Next, five anisotropic conductive films (ACF5-7) were cut into 20 × 30 cm pieces, and each was slit to a width of 2 mm. Five randomly selected 20 mm regions (25 regions for the five films) were cut from each set. The film containing 10 or more conductive particles in a 200 μm longitudinal direction (terminal width direction) of the film was used as the anisotropic conductive film of Example 5. The same procedure was repeated except that the film contained one or two conductive particles per region, to provide the anisotropic conductive film of Comparative Example 2.

[0118] <Evaluation 2 (FOG)> The conductive properties (initial conductivity and conductive reliability) of the connection structures obtained by FOG connection using the three types of anisotropic conductive films produced in Example 5 and Comparative Example 2 were tested and evaluated as follows.

[0119] (Initial conductivity) The following evaluation FPC and glass substrate were used as the electronic components to be FOG-connected. The anisotropic conductive film to be evaluated was cut and sandwiched between the evaluation FPC and glass substrate so that 25 randomly selected locations were positioned between the FPC and the glass substrate. The resulting connections were obtained by heating and pressurizing (180°C, 4.5 MPa, 5 seconds). The longitudinal direction of the anisotropic conductive film was aligned with the transverse direction of the bumps. The electrical resistance of the resulting connection structures was measured using a digital multimeter (34401A, Agilent Technologies) according to the four-terminal method (JIS K7194). For practical purposes, a resistance of 2 Ω or less is desirable. (Continuity reliability) The connection structure used to measure the initial conduction resistance was placed in a thermostatic chamber at 85°C and 85% humidity for 500 hours, and then the conduction resistance was measured again. In practice, a value of 5Ω or less is desirable.

[0120] (Evaluation FPC) A 38μm thick polyimide substrate with tin-plated 8μm thick Cu wiring (L / S=200 / 200) at a 400μm pitch.

[0121] (glass substrate) Glass material: Corning 1737F External size 30mm×50mm Thickness 0.5mm Terminal ITO wiring

[0122] (Evaluation results) The connection structures subjected to the measurement were evaluated as "good" if their initial conduction resistance was 2Ω or less and their conduction resistance after the conduction reliability test was 5Ω or less, and were evaluated as "poor" otherwise. As a result, the conduction characteristics of the connection structures produced using the three types of anisotropic conductive films of Example 5 were good, but the connection structure produced using the anisotropic conductive film of Comparative Example 2 had more nonstandard regions in the regularly arranged regions than in Example 5, and was therefore evaluated as having poor conduction characteristics. [Industrial Applicability]

[0123] The anisotropic conductive film of the present invention has a regularly arranged region in which conductive particles are regularly arranged in an insulating resin binder, and is 5 m or longer in length. Furthermore, within the regularly arranged region, there is a standard region in which there are no areas where a predetermined number or more of conductive particles are missing, and the standard region has a predetermined width in the short direction of the anisotropic conductive film and a predetermined length or longer in the longitudinal direction of the anisotropic conductive film. Therefore, even if there are gaps in the predetermined regularly arranged conductive particles, the anisotropic conductive film can be used for anisotropic conductive connections in substantially the same way as an anisotropic conductive film without gaps. This film is useful as a low-cost joining member for anisotropic conductive connections. [Explanation of symbols]

[0124] 1A, 1B, 1C Anisotropic Conductive Film 1P End of the width in the short direction of the anisotropic conductive film 2, 2a, 2b, 2c, 2d conductive particles 2t Top of conductive particle 2X Conductive particle loss 2Y A series of missing pieces 3. Insulating resin binder 3a Surface of insulating resin binder in the center between adjacent conductive particles 3b, 3c dent 3p tangent plane 4. Insulating adhesive layer 5 Repeating Units 10 Bump, terminal 11 Terminal row 12 Electronic Components D Average particle size of conductive particles L1 lattice axis La Thickness of insulating resin binder Q Area within specifications R Area containing non-standard parts S Any area

Claims

1. An anisotropic conductive film having an ordered arrangement region in which conductive particles are regularly arranged in an insulating resin binder, Within the regularly arranged region, an in-standard region, which does not have out-of-standard portions where a predetermined number or more of conductive particles are missing consecutively, exists over a predetermined width in the short-side direction of the anisotropic conductive film and a predetermined length or more in the longitudinal direction of the anisotropic conductive film, and a region including out-of-standard portions where a predetermined number or more of conductive particles are missing consecutively exists separately from the in-standard region, The regularly arranged region is intended to arrange conductive particles in a 15×15 square lattice within a connection area of ​​0.4 mm 2 , and the predetermined number is 210. An anisotropic conductive film, wherein the predetermined width in the short direction of the anisotropic conductive film is 10% to 95% of the total width in the short direction, and the predetermined length in the long direction is 5 mm to 1000 m.

2. 2. The anisotropic conductive film according to claim 1, wherein the anisotropic conductive film is formed on a release film.

3. 3. The anisotropic conductive film according to claim 1, which is formed into a long shape.

4. 4. The anisotropic conductive film according to claim 3, which has a length of 5 m or more.

5. 2. The anisotropic conductive film according to claim 1, wherein the predetermined width in the lateral direction of the anisotropic conductive film is 20% to 90% of the total width in the lateral direction.

6. The number density of conductive particles is 30 particles / mm ２ More than 50000 pieces / mm ２ 6. The anisotropic conductive film according to claim 1, wherein:

7. The number density of conductive particles is 500 particles / mm ２ More than 35000 pieces / mm ２ 7. The anisotropic conductive film according to claim 6, wherein:

8. 8. The anisotropic conductive film according to claim 1, wherein 10 or more conductive particles are present in an arbitrarily selected region of 200 μm in the longitudinal direction across the entire width of the anisotropic conductive film.

9. 9. The anisotropic conductive film according to claim 1, wherein at least one resin layer is laminated on the insulating resin binder.

10. 10. The anisotropic conductive film according to claim 1, wherein the anisotropic conductive film is in the form of a wound body wound around a reel.

11. A connection structure in which a first electronic component and a second electronic component are anisotropically conductively connected by the anisotropic conductive film according to any one of claims 1 to 10.

12. A method for manufacturing a connection structure in which a first electronic component and a second electronic component are anisotropically conductively connected by the anisotropic conductive film according to any one of claims 1 to 10.

13. A method for manufacturing a connection structure in which a first electronic component having a terminal row and a second electronic component having a terminal row are anisotropically conductively connected to each other by thermocompression bonding the first electronic component and the second electronic component together via an anisotropic conductive film described in any one of claims 1 to 10, wherein the standard area is aligned with the terminal row of the electronic components.

14. The anisotropic conductive film according to claim 1, further comprising, outside the regularly arranged regions, blank regions where no conductive particles are present, randomly arranged regions where conductive particles are randomly arranged, defective areas where a predetermined number or more of conductive particles are missing, or defective areas where conductive particles are agglomerated.

15. 15. The anisotropic conductive film according to claim 14, wherein the anisotropic conductive film has a length of 5 m or more.

16. 16. The anisotropic conductive film according to claim 14, wherein 10 or more conductive particles are present in an arbitrarily selected region of 200 μm in the longitudinal direction across the entire width of the anisotropic conductive film.

17. 17. The anisotropic conductive film according to claim 14, wherein the anisotropic conductive film is in the form of a wound body wound around a reel.

18. A connection structure in which a first electronic component and a second electronic component are anisotropically conductively connected by the anisotropic conductive film according to any one of claims 14 to 17.

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