JP2018093055A - Temporarily crimping method of anisotropic conductive film, temporarily crimping device of anisotropic conductive film, and anisotropic conductive connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide new and improved temporarily crimping method of an anisotropic conductive film and temporarily crimping device of an anisotropic conductive film which can reduce air bubbles in an anisotropic conductive layer, and to provide an anisotropic conductive connection structure.SOLUTION: A temporarily crimping method of an anisotropic conductive film includes: a step of temporarily sticking an anisotropic conductive film onto a surface of a first substrate laminated on an optical resin layer; and a step of temporarily crimping the anisotropic conductive film onto the first substrate by pressing a pressing surface of a tool head against the anisotropic conductive film temporarily stuck onto the first substrate, where the pressing surface is curved into a projection shape, and a radius of curvature of the pressing surface is more than 5.5 mm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for temporarily pressing an anisotropic conductive film, a device for temporarily pressing an anisotropic conductive film, and an anisotropic conductive connection structure.

  For example, as disclosed in Patent Documents 1 to 6, a technique for anisotropic conductive connection between a plurality of substrates is known. In this technique, first, as disclosed in Patent Documents 1 and 2, an anisotropic conductive connection film is temporarily pasted on one substrate (first substrate). Next, the anisotropic conductive film is temporarily pressure-bonded onto the first substrate by pressing the tool head against the anisotropic conductive film. Then, the other board | substrate (2nd board | substrate) is laminated | stacked on an anisotropic conductive film, and several board | substrates are anisotropically conductive-connected by carrying out this pressure bonding to the anisotropic conductive film. . The resulting anisotropic conductive connection structure includes a plurality of substrates and an anisotropic conductive layer that anisotropically connects these substrates. In addition, the electrode terminal is provided on each board | substrate and an anisotropic conductive layer connects these electrode terminals anisotropically conductively.

JP 2007-324471 A JP 2011-17011 A JP 2010-67922 A JP 2009-260379 A JP-A-5-273570 JP-A-10-310743

  By the way, when the anisotropic conductive film is temporarily pressure-bonded onto the first substrate, a gap is formed between the anisotropic conductive film and the first substrate. In some cases, it remained. Such bubbles are particularly likely to remain when the first substrate is a touch panel substrate. The reason is as follows.

  First, the first substrate is often composed of a plastic substrate (eg, a polyethylene terephthalate (PET) substrate). Since such a plastic substrate has low rigidity, it is likely to be deformed during temporary pressure bonding. Therefore, bubbles are likely to be generated during temporary pressure bonding.

  Secondly, the first substrate is often laminated on the surface of an image display device or the like via an optical resin layer. Such an optical resin layer is easily deformed at the time of temporary pressure bonding. As a result, the first substrate easily deforms following the deformation of the optical resin layer. Therefore, bubbles are likely to be generated during temporary pressure bonding.

  Third, an electrode group for detecting a user's touch operation is disposed on the first substrate. In order to prevent cracks from occurring in the terminal array of anisotropic connection extended from such an electrode group (the terminal array may be provided with a material different from that of the electrode group), the pressure at the time of the main pressure bonding is as much as possible. There is a need to lower it. In particular, in recent years, these electrode groups and anisotropic connection terminal portions are often formed of metal films. When the electrode group and the terminal portion for anisotropic connection are made of a metal film, the electrode group is likely to crack, so the pressure during the main press bonding needs to be extremely low. In addition, since the first substrate itself is easily deformed, it is required that the pressure during the main press bonding be as low as possible. And when the pressure at the time of main press-bonding is lowered, the resin constituting the anisotropic conductive film is difficult to flow at the time of main press-bonding, so bubbles are difficult to escape. Therefore, bubbles tend to remain after the main press bonding.

  Such air bubbles not only impair the appearance of the anisotropic conductive layer, but also reduce the reliability (for example, connection resistance) of the anisotropic conductive connection portion. For this reason, it has been strongly demanded to reduce bubbles in the anisotropic conductive layer after the main pressure bonding.

  However, such a technique has not been fully studied. For example, Patent Documents 3 to 6 disclose techniques that devise the shape of the tool head at the time of the main pressure bonding, but these techniques cannot reduce bubbles in the anisotropic conductive layer.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a new and improved anisotropy capable of reducing bubbles in the anisotropic conductive layer. An object of the present invention is to provide a method for temporarily pressing a conductive film, a device for temporarily pressing an anisotropic conductive film, and an anisotropic conductive connection structure.

  In order to solve the above problems, according to one aspect of the present invention, a step of temporarily attaching an anisotropic conductive film to a surface of a first substrate laminated on an optical resin layer, Temporarily pressing the anisotropic conductive film onto the first substrate by pressing the pressing surface of the tool head against the temporarily attached anisotropic conductive film, and the pressing surface is curved in a convex shape Thus, there is provided a method for temporarily pressing an anisotropic conductive film, wherein the radius of curvature of the pressing surface is greater than 5.5 mm.

  Here, the pressing surface may be curved convexly in the width direction of the anisotropic conductive film.

  Further, the first substrate may be a plastic substrate.

  The first substrate may be a touch panel substrate.

  Further, the optical resin layer may be laminated on the third substrate.

  Further, the third substrate may be a substrate of an image display device.

  According to another aspect of the present invention, there is provided an apparatus for temporarily bonding an anisotropic conductive film having a tool head having a pressing surface curved in a convex shape and having a curvature radius of the pressing surface of more than 5.5 mm. .

  According to another aspect of the present invention, a first substrate laminated on an optical resin layer, and a second substrate laminated on the first substrate via an anisotropic conductive layer, An anisotropic conductive connection structure is provided in which the area of the bubbles contained in the anisotropic conductive layer is less than 15% with respect to the total area of the anisotropic conductive layer.

  As described above, according to the present invention, since the pressing surface of the tool head is curved in a convex shape, air bubbles easily escape during provisional pressure bonding. For this reason, the amount of bubbles remaining after provisional pressure bonding is reduced, and as a result, bubbles in the anisotropic conductive layer can be reduced.

It is a sectional side view for demonstrating the temporary crimping | compression-bonding method of the anisotropic conductive film which concerns on embodiment of this invention. It is a sectional side view for demonstrating the temporary crimping | compression-bonding method of the anisotropic conductive film which concerns on the same embodiment. It is a sectional side view for demonstrating the main crimping | compression-bonding method of the anisotropic conductive film which concerns on the same embodiment. It is a sectional side view for demonstrating the structure of the anisotropic conductive connection structure which concerns on the same embodiment. It is a sectional side view for demonstrating the conventional temporary crimping | compression-bonding method of an anisotropic conductive film. It is a sectional side view for demonstrating the conventional temporary crimping | compression-bonding method of an anisotropic conductive film.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Conventional Temporary Pressure Bonding Method for Anisotropic Conductive Film>
As a result of intensive studies on a conventional method for temporarily pressing an anisotropic conductive film, the present inventor has come up with the method for temporarily pressing an anisotropic conductive film according to the present embodiment. Therefore, first, a conventional method for temporarily pressing an anisotropic conductive film will be described with reference to FIGS.

  In the example shown in FIG. 5, the first substrate 30 is laminated on the third substrate 70 via the optical resin layer 40. The first substrate 30 is a substrate for a touch panel, specifically a plastic substrate. Therefore, the first substrate 30 has low rigidity. In addition, an electrode group for detecting a touch operation by a user is formed on the first substrate 30, and an electrode terminal group connected to the electrode group is formed at an end of the first substrate 30. Yes. The electrode terminal group is anisotropically conductively connected to the electrode terminal group of the second substrate (not shown). The second substrate is a flexible substrate, for example. The third substrate 70 is a substrate of the image display device.

  Then, one surface of the anisotropic conductive film 10 is temporarily attached onto the first substrate 30. Specifically, one surface of the anisotropic conductive film 10 is temporarily pasted on the region where the electrode terminal group is formed. Here, the release film 20 is attached to the other surface of the anisotropic conductive film 10. Next, the buffer material 200 is placed on the release film 20. Next, as shown in FIG. 6, the pressing surface 510 of the temporary press-bonding tool head 500 is pressed against the buffer material 200 by moving the temporary press-bonding tool head 500 in the direction of arrow A (ie, downward). Thereby, the anisotropic conductive film 10 is temporarily pressure-bonded to the first substrate 30. Here, the pressing surface 510 is a flat surface.

  At this time, the first substrate 30 and the optical resin layer 40 are greatly deformed, and a gap, that is, a bubble B is formed between the anisotropic conductive film 10 and the first substrate 30. And since the press surface 510 is a flat surface, the pressure from the edge part of the press surface 510 tends to become large. For this reason, it is temporarily pressure-bonded to the first substrate 30 from the end of the anisotropic conductive film 10. For this reason, the bubbles B are difficult to escape and remain between the anisotropic conductive film 10 and the first substrate 30. Thereafter, the first substrate 30 and the second substrate are subjected to main pressure bonding. However, since the pressure of the main pressure bonding cannot be increased, the bubbles B tend to remain.

  As described above, the reason why bubbles are generated during temporary pressure bonding is that the pressing surface 510 of the tool head 500 for temporary pressure bonding is flat. Therefore, the inventor paid attention to the shape of the pressing surface 510. As a result, the present inventor has conceived the anisotropic conductive connection method according to the present embodiment. Hereinafter, this embodiment will be described in detail.

<2. Temporary Pressure Bonding Method for Anisotropic Conductive Film According to this Embodiment>
Below, based on FIGS. 1-2, the temporary crimping | compression-bonding method of the anisotropic conductive film which concerns on this embodiment is demonstrated.

(2-1. Temporary pasting step)
First, the anisotropic conductive film 10 is temporarily attached on the first substrate 30. The first substrate 30 is laminated on the third substrate 70 via the optical resin layer 40.

  The first substrate 30 is a touch panel substrate. Accordingly, an electrode group for detecting a touch operation by the user and an electrode terminal group connected to these electrode groups are formed on the first substrate 30.

  The material which comprises an electrode group and an electrode terminal group is not ask | required in particular. For example, the electrode group and the electrode terminal group may be made of ITO (indium tin oxide) or a metal film. Examples of the metal constituting the metal film include gold, silver, copper, aluminum, zinc, and alloys of two or more thereof. An insulating layer may be formed on the surface of the metal film. The insulating layer may be a rust-proofing layer that has been rust-proofed. The electrode group and the electrode terminal group may be composed of metal particles. In this case, a recess is formed on the first substrate 30 and the recess is filled with metal particles. As a metal which comprises a metal particle, gold | metal | money, silver, copper, aluminum, zinc, these 2 or more types of alloys, etc. are mentioned, for example. Moreover, the electrode group and the electrode terminal group may be comprised with the metal nanowire. In this case, the metal nanowire is fixed on the first substrate 30 by a binder. Examples of the metal constituting the metal nanowire include Ag, Au, Ni, Cu, Pd, Pt, Rh, Ir, Ru, Os, Fe, Co, and Sn. The metal nanowire may be subjected to a treatment (for example, dyeing or blackening treatment) for lowering the haze value (that is, reducing visibility).

  The first substrate 30 is made of a plastic substrate having transparency. For example, examples of the first substrate 30 include polycarbonate, acrylic, polyethylene terephthalate (PET), triacetyl cellulose, and cyclic olefin resin (COC). The first substrate 30 may be made of transparent glass or the like.

  Further, the tensile elastic modulus of the first substrate 30 may be about 1800 to 4500 MPa, for example. For example, when the first substrate 30 is made of PET, the tensile elastic modulus of the first substrate 30 is 2000 to 4100 MPa. Moreover, when the 1st board | substrate 30 is comprised by COC, the tensile elasticity modulus of the 1st board | substrate 30 will be 2600-3000 MPa.

  The thickness of the first substrate 30 is not particularly limited, and may be set as appropriate according to characteristics required for the first substrate 30. As an example, 25-300 micrometers is mentioned. However, as the first substrate 30 is thicker, bubbles tend to be less likely to be generated during temporary pressure bonding.

  In addition, the 1st board | substrate 30 is not limited to the example mentioned above, What is necessary is just a board | substrate used as the object of anisotropic conductive connection. However, when the first substrate 30 has the above-described configuration, the first substrate 30 is very easily deformed, so that bubbles are likely to be generated during temporary pressure bonding. Furthermore, since the pressure cannot be increased during the main pressure bonding, bubbles tend to remain. For this reason, the effect of this embodiment is acquired suitably.

  The optical resin layer 40 is a layer for adhering the first substrate 30 to the third substrate 70, and is made of, for example, OCA (Optically Clear Adhesive), OCR (Optically Clear Resin), or the like. The optical resin layer 40 is very soft and easily deforms during temporary pressure bonding. As a result, the first substrate easily deforms following the deformation of the optical resin layer. Therefore, bubbles are likely to be generated during temporary pressure bonding. Therefore, bubbles are likely to be generated during temporary pressure bonding.

The thickness of the optical resin layer 40 is not particularly limited. However, the thinner the optical resin layer 40 is, the more likely that bubbles are less likely to be generated during temporary pressure bonding. For this reason, the thickness of the optical resin layer 40 is preferably, for example, 250 μm or less, and more preferably 100 μm or less. Further, the tensile elastic modulus of the optical resin layer 40 is not particularly limited, but may be, for example, 10 to 200 KPa. Alternatively, the storage elastic modulus at 25 ° C. may be 1 × 10 ³ to 2 × 10 ⁶ Pa.

  The third substrate 70 is, for example, a substrate of an image display device, that is, a top plate of the image display device. The material in particular of the 3rd board | substrate 70 is not restrict | limited, For example, the material similar to a 1st board | substrate may be sufficient. The third substrate 70 is not limited to the substrate of the image display device, and may be another type of substrate.

  One side of the anisotropic conductive film 10 is temporarily attached on the first substrate 30. Specifically, the anisotropic conductive film 10 is temporarily attached to the region where the electrode terminal group is formed. A release film 20 is attached to the other surface of the anisotropic conductive film 10. The release film 20 may be omitted.

  The anisotropic conductive film 10 becomes an anisotropic conductive layer 10a (see FIG. 4) by a final press-bonding described later, and a first substrate 30 (more specifically, an electrode terminal group formed on the first substrate 30). ) And a second substrate 60 described later (more specifically, an electrode terminal group formed on the second substrate 60) are anisotropically conductively connected.

  The anisotropic conductive film 10 includes a film-forming resin, a curable resin, and conductive particles. The curable resin includes a polymerizable compound and a curing initiator.

  The film-forming resin is a resin for maintaining the shape of the anisotropic conductive film. As the film forming resin, for example, various resins such as an epoxy resin, a phenoxy resin, a polyester urethane resin, a polyester resin, a polyurethane resin, an acrylic resin, a polyimide resin, and a butyral resin can be used. In the present embodiment, only one of these film-forming resins can be used, or two or more can be used in any combination. In addition, it is preferable that film forming resin is a phenoxy resin from a viewpoint of making film forming property and adhesive reliability favorable.

  The polymerizable compound is a resin that is cured by a curing initiator. The cured polymerizable compound bonds the first substrate 30 and the second substrate 60 and holds the conductive particles in the anisotropic conductive layer. Examples of the polymerizable compound include an epoxy polymerizable compound and an acrylic polymerizable compound. The epoxy polymerizable compound is a monomer, oligomer, or prepolymer having one or more epoxy groups in the molecule. As epoxy polymerizable compounds, various bisphenol type epoxy resins (bisphenol A type, F type, etc.), novolac type epoxy resins, various modified epoxy resins such as rubber and urethane, naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolac type Examples thereof include epoxy resins, stilbene type epoxy resins, triphenolmethane type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, and prepolymers thereof.

  The acrylic polymerizable compound is a monomer, oligomer, or prepolymer having one or more acrylic groups in the molecule. Examples of the acrylic polymerizable compound include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, epoxy acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylol propane triacrylate, dimethylol tricyclodecane diacrylate, and tetramethylene glycol. Tetraacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis [4- (acryloxymethoxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy) phenyl] propane, Examples include dicyclopentenyl acrylate, tricyclodecanyl acrylate, tris (acryloxyethyl) isocyanate, and urethane acrylate. That. In the present embodiment, any one of the polymerizable compounds listed above may be used, or two or more may be used in any combination.

  The curing initiator is, for example, a thermosetting initiator. The thermosetting initiator is a material that is cured together with the polymerizable compound by heat. The kind of thermosetting initiator is not particularly limited. Examples of the thermosetting initiator include a thermal anion or thermal cation curing initiator that cures the epoxy polymerizable compound, and a thermal radical polymerization curing agent that cures the acrylic polymerizable compound. In this embodiment, an appropriate thermosetting initiator may be selected depending on the polymerizable compound. In addition, a photocuring initiator is mentioned as another example of a curing initiator. Examples of the photocuring initiator include a photoanion or photocationic curing initiator that cures an epoxy polymerizable compound, and a photo radical polymerization curing agent that cures an acrylic polymerizable compound.

  The anisotropic conductive film may contain various additives in addition to the above components. Examples of additives that can be added to the anisotropic conductive film include silane coupling agents, inorganic fillers, colorants, antioxidants, and rust inhibitors. The kind of silane coupling agent is not particularly limited. Examples of the silane coupling agent include epoxy-based, amino-based, mercapto-sulfide-based, and ureido-based silane coupling agents.

  The inorganic filler is an additive for adjusting the fluidity and film strength of the anisotropic conductive film. The kind of inorganic filler is not particularly limited. Examples of the inorganic filler include silica, talc, titanium oxide, calcium carbonate, and magnesium oxide.

  The conductive particles are composed of an electrode terminal group on the first substrate 30 (hereinafter also referred to as “first electrode terminal group”) and an electrode terminal group (hereinafter referred to as “first electrode terminal group”) in the anisotropic conductive layer 10a. , Also referred to as “second electrode terminal group”). Specifically, the conductive particles sandwiched between the first electrode terminal group and the second electrode terminal group in the anisotropic conductive layer 10a make these electrode terminal groups conductive. On the other hand, other conductive particles (for example, conductive particles that have entered the gap between the electrode terminals constituting the first electrode terminal group, and conductivity that have entered the gap between the electrode terminals that constitute the second electrode terminal group. Particles or the like do not conduct between any terminals (that is, short-circuit in the form of continuous conductive particles between the electrode terminals constituting the first electrode terminal group, between the electrode terminals constituting the second electrode terminal group Does not cause short circuit in the form of continuous conductive particles). Accordingly, the conductive particles maintain the insulation between the electrode terminals constituting the first electrode terminal group and between the electrode terminals constituting the second electrode terminal group in the anisotropic conductive layer 10a, while maintaining the insulation between the electrode terminals constituting the first electrode terminal group. The electrode terminal group and the second electrode terminal group can be made conductive. That is, the conductive particles are sandwiched between the first electrode terminal group and the second electrode terminal group in the anisotropic conductive layer 10a, thereby conducting them and making an anisotropic conductive connection. The conductive particles may be dispersed to such an extent that they do not short-circuit, and may be arranged individually on the anisotropic conductive film. This arrangement is appropriately set depending on the size of each electrode terminal, the distance in the arrangement direction of the electrode terminals, and the like, but may be regular.

  The structure of the conductive particles is not particularly limited, and may be so-called metal-coated resin particles or metal particles. When the conductive particles are metal-coated resin particles, continuity between the first electrode terminal group and the second electrode terminal group can be maintained for a long time due to repulsion after compression of the resin particles. That is, the first electrode terminal group and the second electrode terminal group can be directly and stably anisotropically conductively connected. The resin particles constituting the core of the metal-coated resin particles are preferably particles made of a plastic material excellent in compressive deformation. Examples of the material constituting the resin particles include (meth) acrylate resins, polystyrene resins, styrene- (meth) acrylic copolymer resins, urethane resins, epoxy resins, phenol resins, acrylonitrile / styrene (AS) resins. Benzoguanamine resin, divinylbenzene resin, styrene resin, polyester resin and the like. For example, when forming resin particles with a (meth) acrylate resin, the (meth) acrylic resin has a (meth) acrylic acid ester and, if necessary, a reactive double bond copolymerizable therewith. A copolymer of a compound and a bifunctional or polyfunctional monomer is preferable. Two or more kinds of conductive particles may be used. In this case, for example, two or more different metal-coated resin particles may be used. Therefore, the combination of conductive particles is not particularly limited.

  The coating layer that coats the resin particles is made of a conductive material. Examples of the material constituting the coating layer include silver, gold, nickel, copper, and palladium. The coating layer may be composed of any one or more of these. In addition, when electroconductive particle is comprised with a metal particle, electroconductive particle can be comprised with these materials. When the conductive particles are composed of metal particles, the metal constituting the conductive particles may be the same as the metal constituting the coating layer.

  The thickness of the anisotropic conductive film is not particularly limited. However, if the film becomes too thick, the amount of unnecessary resin becomes too large, causing problems with fluidity. Therefore, 100 micrometers or less are preferable and 40 micrometers or less are more preferable. Since handling will become difficult when it becomes too thin, 5 micrometers or more are preferable and 12 micrometers or more are more preferable. Moreover, the anisotropic conductive film may have a long shape. A long anisotropic conductive film may be cut into an appropriate length for use.

(2-2. Temporary pressure bonding process)
Next, the anisotropic conductive film 10 is temporarily bonded onto the first substrate 30. Specifically, the buffer material 200 is installed on the release film 20. Next, as shown in FIG. 2, the pressing surface 110 of the temporary press-bonding tool head 100 is pressed against the buffer material 200 by moving the temporary press-bonding tool head 100 in the direction of arrow A (ie, downward). Thereby, the anisotropic conductive film 10 is temporarily pressure-bonded to the first substrate 30.

  Here, the pressing surface 110 of the temporary press-bonding tool head 100 is curved in a convex shape. The bending direction is not particularly limited, and may be curved in the width direction of anisotropic conductive film 10 or may be curved in the length direction of anisotropic conductive film 10. In the example of FIG. 2, the pressing surface 110 is curved in the width direction of the anisotropic conductive film 10. In the case of bending in the width direction, the bubbles can be easily removed by temporarily pressing the bubbles so as to push out the bubbles from the center of the anisotropic conductive film. This is because the distance traveled by the bubbles is relatively small.

  The radius of curvature of the pressing surface 110 is over 5.5 mm. In this case, the amount of bubbles generated during temporary pressure bonding is reduced. The upper limit value of the curvature radius is not particularly limited, and may be adjusted depending on the size of the anisotropic conductive film 10, for example. For example, when the pressing surface 110 is curved in the width direction of the anisotropic conductive film 10, the radius of curvature may be increased as the width of the anisotropic conductive film 10 is wider. The protrusion height h of the pressing surface 110 (distance from the tip end to the base end of the convex portion) is not particularly limited, but may be about 0.03 to 0.3 mm, preferably 0.05 to 0.00 mm. 2 mm.

  The thickness of the buffer material 200 is not particularly limited, but may be 0.1 to 0.5 mm, and preferably 0.2 to 0.3 mm.

  The pressurizing temperature and the applied pressure at the time of temporary pressure bonding are, for example, 60 to 80 ° C., 1 MPa or more and less than 2 MPa. The pressing time is appropriately adjusted depending on the material of the anisotropic conductive film 10 or the like, but is set to a value at least enough to fix the anisotropic conductive film 10 on the first substrate 30.

  During the temporary pressure bonding, the first substrate 30 and the optical resin layer 40 are greatly deformed. However, since the pressing surface 110 is curved in a convex shape, the pressing surface 110 can follow these deformations. Therefore, bubbles are not easily generated between the first substrate 30 and the anisotropic conductive film 10. Furthermore, since the pressure from the end of the pressing surface 110 is reduced, the difference between the speed at which the end of the anisotropic conductive film 10 is temporarily pressed and the speed at which the other part is temporarily pressed is reduced. For this reason, even if bubbles are generated, the bubbles easily escape from the end of the anisotropic conductive film 10. Therefore, it becomes difficult for bubbles to remain after temporary pressure bonding.

  Specifically, the area in plan view of the bubbles after provisional pressure bonding is 15% with respect to the total area in plan view of the anisotropic conductive film (total area of the portion bonded to the first substrate 30). Less than. In addition, the area of a bubble can be measured by observing the anisotropic conductive film 10 after temporary pressure bonding with a metal microscope. You may image the anisotropic conductive film 10 and observe the image obtained by this. In addition, the size of the bubble itself is various, and there may be a bubble having a size that cannot be sufficiently confirmed even by a metal microscope. For this reason, for example, a minimum rectangle inscribed in the bubble may be defined, and a bubble having a long axis length of 100 μm or more may be set as a measurement target. The area of the bubbles measured by this method in plan view (total area of the bubbles to be measured) is less than 15% with respect to the total area of the anisotropic conductive film in plan view. Note that the temporary pressure bonding step is performed by a temporary pressure bonding apparatus including the tool head 100. The temporary crimping apparatus may be configured similarly to the conventional temporary crimping apparatus except that the temporary crimping apparatus includes the tool head 100. Here, the tool head 100 is obtained, for example, by grinding a pressing surface of a conventional tool head by scraping. Moreover, you may perform the temporary sticking process using the tool head 100 mentioned above. In this case, first, the anisotropic conductive film 10 is placed on the first substrate 30 such that the exposed surface of the anisotropic conductive film 10 contacts the first substrate 30. Next, the pressing surface 110 of the tool head 100 is pressed against the release film 20 from above the release film 20. Thereby, temporary attachment is performed. In this case, it is possible to expect the same effect as that obtained by temporary bonding by temporary bonding. That is, the pressing surface 110 can follow the deformation of the first substrate 30 and the optical resin layer 40 during temporary attachment. Therefore, bubbles are not easily generated between the first substrate 30 and the anisotropic conductive film 10. Furthermore, since the pressure from the end portion of the pressing surface 110 is reduced, even if bubbles are generated, the bubbles easily escape from the end portions of the anisotropic conductive film 10. Therefore, the temporary bonding performed using the tool head 100 is included in the temporary pressure bonding in the present embodiment. Usually, since the anisotropic conductive film 10 is fixed to the substrate 30 side after provisional pressure bonding, the release film 20 is removed thereafter.

<3. Main crimping process>
Next, this pressure bonding is performed. The method of this press-bonding is not particularly limited, and may be a method similar to the conventional method. Hereinafter, the contents of the main press bonding step will be described with reference to FIGS. 3 and 4. First, the release film 20 is peeled off from the anisotropic conductive film 10.

  Next, the second substrate 60 is laminated on the anisotropic conductive film 10. More specifically, the second substrate 60 is laminated on the anisotropic conductive film 10 so that the second electrode terminal group formed on the second substrate 60 faces the anisotropic conductive film 10. To do.

  Here, the type of the second substrate 60 is not particularly limited, but may be, for example, a flexible substrate. Examples of the material constituting the flexible substrate include thin-film metal or glass in addition to resins such as polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic resin. Moreover, the material which comprises a 2nd electrode terminal group is not ask | required in particular, You may be comprised with the material similar to a 1st electrode terminal group.

  Next, the second substrate 60 is finally bonded to the anisotropic conductive film 10. Specifically, the buffer material 200 a is installed on the second substrate 60. Next, the main crimping tool head 400 is pressed against the cushioning material 200a by moving the main crimping tool head 400 in the direction of arrow A (ie, downward). As a result, the second substrate 60 is finally pressure-bonded onto the anisotropic conductive film 10. The pressurizing temperature and the applied pressure during the main press bonding vary depending on the material such as the anisotropic conductive film, but may be set within a range of, for example, 120 to 190 ° C. and 0.5 MPa or more and less than 5 MPa. The pressing time is appropriately adjusted depending on the material of the anisotropic conductive film 10 and the like, but is set to a value at least that allows the anisotropic conductive film 10 to flow and cure. By the main compression bonding, the anisotropic conductive film 10 is cured to become an anisotropic conductive layer 10a as shown in FIG. That is, the anisotropic conductive connection structure 1 is produced. The main crimping process may be performed by a conventional main crimping apparatus.

<4. Anisotropic Conductive Connection Structure>
FIG. 4 shows the structure of the anisotropic conductive connection structure 1 manufactured according to this embodiment. The anisotropic conductive connection structure 1 includes a first substrate 30, an optical resin layer 40, a second substrate 60, an anisotropic conductive layer 10 a, and a third substrate 70. According to the present embodiment, the amount of bubbles at the time of provisional pressure bonding is reduced. Specifically, the area of the bubbles in plan view is less than 15% with respect to the total area of the anisotropic conductive film 10 in plan view. For this reason, the amount of bubbles in the anisotropic conductive layer 10a is also reduced. Specifically, the area of the bubbles contained in the anisotropic conductive layer 10a in plan view is less than 15% with respect to the total area of the anisotropic conductive layer 10a in plan view. Here, the area of the bubbles contained in the anisotropic conductive layer 10a in plan view is measured by observing the anisotropic conductive layer 10a with a metal microscope from the first substrate 30 or the second substrate 60 side. Is done. The method for determining the bubbles to be measured may be the same as that for observing the bubbles in the anisotropic conductive film 10.

  Next, examples of the present embodiment will be described. In this example, the following simulation test was performed to verify the amount of bubbles after provisional pressure bonding. First, as the anisotropic conductive film 10, CP923AM-18 manufactured by Dexerials Corporation was prepared. The width of the anisotropic conductive film 10 was 2.0 mm. The anisotropic conductive film 10 includes an acrylic polymerizable compound as a polymerizable compound. The particle size of the conductive particles was 10 μm. Moreover, the peeling film 20 was affixed on one surface. In addition, an acrylic double-sided pressure-sensitive adhesive tape having a thickness of 0.15 mm and a tensile modulus of 50 to 100 KPa was prepared as a substitute for the optical resin layer 40. The tensile elastic modulus of the acrylic double-sided pressure-sensitive adhesive tape is about the same as that of OCA and OCR constituting the optical resin layer 40. Since the presence or absence of bubbles depends on the softness of the optical resin layer 40, that is, the tensile elastic modulus, the amount of bubbles can be verified by using this double-sided tape. A PET film having a thickness of 0.1 mm was prepared as the first substrate 30. These PET films had a tensile modulus of 4 GPa. In addition, although the electrode group and electrode terminal group are not formed in the surface of the 1st board | substrate 30, since these are very thin, the presence or absence of these has little influence on the presence or absence of bubble generation. Therefore, the amount of bubbles can be verified even if the electrode group and the electrode terminal group are not formed on the surface of the first substrate 30.

  And the double-sided tape was affixed on the glass substrate (3rd board | substrate 70), and also the 1st board | substrate 30 was affixed on it. Next, the anisotropic conductive film 10 was temporarily attached onto the first substrate 30. Next, a cushioning material 200 (thickness 0.2 mm) made of silicon rubber was placed on the release film 20. Next, the pressing surface 110 of the temporary pressure bonding tool head 100 was pressed against the cushioning material 200. Thereby, the anisotropic conductive film 10 was temporarily pressure-bonded to the first substrate 30.

  Here, the pressing surface 110 of the temporary press-bonding tool head 100 was curved in a convex shape in the width direction of the anisotropic conductive film 10. Moreover, the curvature radius was 50 mm and the protrusion height was 0.05 mm. Moreover, the tool width (length in the bending direction) was 5.0 mm. Moreover, the pressurization temperature and the applied pressure at the time of temporary pressure bonding were 60 ° C. and 1 MPa, and the pressurization time was 1 second.

Next, the amount of bubbles, specifically the area in plan view, was measured by observing the anisotropic conductive film 10 after the temporary pressure bonding with a metal microscope. And the area in the planar view of a bubble was evaluated with the following evaluation criteria. If evaluation more than C evaluation is obtained, there will be no problem in practical use.
A: The area of the bubble in plan view is less than 5% of the total area of the anisotropic conductive film 10 in plan view. B: The area of the bubble in plan view of the anisotropic conductive film 10 is in plan view. 5% or more and less than 10% with respect to the total area C: The area of the bubbles in plan view is 10% or more and less than 15% with respect to the total area of the anisotropic conductive film 10 in plan view D: In the plan view of the bubbles Is 15% or more of the total area of the anisotropic conductive film 10 in plan view

  Subsequently, the same simulation test was repeated by changing the thickness of the first substrate 30, the radius of curvature of the temporary press-bonding tool head 100, the protruding height, and the thickness of the buffer material 200. The results are summarized in Table 1.

  As is clear from Table 1, it was found that the amount of bubbles was reduced when temporary pressing was performed with the temporary pressing tool head 100 having the pressing surface 110 having a curvature radius of more than 5.5 mm. It was also found that the amount of bubbles tends to decrease as the buffer material 200 is thinner and the first substrate 30 is thicker.

  In addition, when the anisotropic conductive connection was performed with the anisotropic conductive film 10 used in Example 1, a plurality of circuit boards were subjected to provisional pressure bonding under the conditions shown in Example 1, and there was no problem in practical use. Conductive connection structure 1 could be produced.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Anisotropic conductive connection structure 10 Anisotropic conductive film 20 Peeling film 30 1st board | substrate 40 Optical resin layer 60 2nd board | substrate 70 3rd board | substrate 100 Tool surface 110 for temporary crimping | pressing surfaces 200 Buffer material 500 Temporary Crimping tool head 510 Press surface B Bubble

Claims (8)

Temporarily attaching an anisotropic conductive film to the surface of the first substrate laminated on the optical resin layer;
Temporarily pressing the anisotropic conductive film onto the first substrate by pressing the pressing surface of the tool head against the anisotropic conductive film temporarily bonded onto the first substrate. ,
The pressing surface is curved in a convex shape,
The method for temporarily pressing an anisotropic conductive film, wherein the radius of curvature of the pressing surface is greater than 5.5 mm.   The method according to claim 1, wherein the pressing surface is curved in a convex shape in the width direction of the anisotropic conductive film.   The method for temporarily pressing an anisotropic conductive film according to claim 1, wherein the first substrate is a plastic substrate.   The method for temporarily pressing an anisotropic conductive film according to claim 3, wherein the first substrate is a substrate for a touch panel.   The said optical resin layer is the temporary crimping | compression-bonding method of the anisotropic conductive film of any one of Claims 1-4 currently laminated | stacked on the 3rd board | substrate.   The method according to claim 5, wherein the third substrate is a substrate of an image display device. A tool head having a convexly curved pressing surface;
An apparatus for temporarily pressing an anisotropic conductive film, wherein a radius of curvature of the pressing surface is greater than 5.5 mm. A first substrate laminated on the optical resin layer, and a second substrate laminated on the first substrate via an anisotropic conductive layer,
The anisotropic conductive connection structure, wherein an area of the bubbles contained in the anisotropic conductive layer in a plan view is less than 15% with respect to a total area of the anisotropic conductive layer in a plan view.

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