JP6209313B2 - Anisotropic conductive film, connection structure, method for manufacturing connection structure, and connection method - Google Patents

Description

  The present invention relates to a flexible display and an electronic component using an anisotropic conductive connection layer and an anisotropic conductive connection layer used when mounting an electronic component such as a flexible printed wiring board and a semiconductor element on a flexible display. The present invention relates to a connected connection structure, a connection method for connecting a flexible display and an electronic component using an anisotropic conductive connection layer, and a method for manufacturing a connection structure by this connection method.

  As a technique for mounting an electronic component such as a semiconductor element on a substrate, for example, a flip chip mounting method in which the electronic component is mounted on the substrate in a so-called face-down state is widely used. In the flip chip mounting method, an anisotropic conductive film is interposed between a terminal of an electronic component and a terminal provided on a substrate for the purpose of improving connection reliability and the like. And mechanical connections are made. The anisotropic conductive film is obtained by dispersing conductive particles in an adhesive containing a resin or the like. The conductive particles are, for example, particles obtained by applying nickel or gold plating to resin particles.

  In such a mounting method, for example, in Patent Document 1, the surface of the terminal of the electronic component or the terminal of the wiring board is made flat, and the conductive particles are uniformly crushed to provide the terminals of the electronic component and the wiring board. The electrical connection with the connected terminal is made good.

  This mounting method is also used for liquid crystal displays and flexible displays. The liquid crystal display has a Young's modulus as high as 72 GPa and is not easily deformed. The liquid crystal display is easily damaged by external pressure or the like. On the other hand, a flexible display using a flexible plastic as a base material is very thin and has flexibility, so that it can be bent and is not easily damaged, and can be used for electronic paper or a roll-up screen.

  In a flexible display, the transparent electrode (ITO etc.) in the display area extends and is connected to electronic parts such as IC chip and flexible printed wiring board at the end of the base material made of plastic etc. Terminals are provided. In the flexible display, the connection terminals are provided directly below or in the vicinity of the display area, and the terminals are miniaturized and the pitch is reduced in order to cope with high-density mounting. As described above, the anisotropic conductive film is used for electrical connection between the terminals thus miniaturized and narrowed in pitch and terminals such as electronic parts and plexi- ble printed wiring boards (for example, Patent Document 2).

  In a flexible display, since a flexible base material such as polyimide or polyethylene terephthalate is used, when using a general anisotropic conductive film used for connection with electronic components, and connected by pressure, Problems such as cracks in the terminals starting from the conductive particles, cracks in the base material, or destruction may occur. For example, when directly connecting an electronic component such as an IC chip on the substrate of the flexible display, unlike the case of the flexible printed wiring board connected by the wiring width, the IC chip etc. are dotted with bumps serving as terminals, Since the pressure applied at the time of connection is also concentrated on the point, cracks are likely to occur.

  In the flexible display, since a mounting area for electronic components exists directly below or in the vicinity of the display unit, it is narrower than a case where electronic components are simply mounted on terminals provided on the wiring board as described in Patent Document 1 described above. It is necessary to particularly suppress the occurrence of cracks so that cracks do not occur in the forehead mounting region. In a flexible display, if an electronic component is connected, if the terminal is cracked or the flexible substrate is destroyed, the display may be cracked or destroyed. Therefore, it is required to suppress the generation of cracks due to the connection of electronic components and the destruction of the base material.

JP 2009-111043 A JP 2009-242508 A

  The present invention has been proposed in view of such a conventional situation, and mechanically and electrically connects a terminal provided on a flexible display and a terminal of an electronic component with an anisotropic conductive connection material. When using the anisotropic conductive connection layer and anisotropic conductive connection layer that can suppress cracks in the terminals provided on the flexible display and cracks in the flexible display itself, It is an object of the present invention to provide a connection structure in which components are connected, a connection method in which a flexible display and an electronic component are connected using an anisotropic conductive connection layer, and a method of manufacturing a connection structure by this connection method.

The manufacturing method of the connection structure according to the present invention that achieves the above-described object includes a flexible display and an electronic component in which an anisotropic conductive connection layer is interposed between a terminal provided on the flexible display and a terminal of the electronic component. The electronic component is mounted on the flexible display so that the terminal of the electronic component faces the terminal provided on the flexible display through the anisotropic conductive connection layer. Mounting step, pressurizing the electronic component against the flexible display, connecting the terminal provided on the flexible display and the terminal of the electronic component with an anisotropic conductive connection layer, and conductive particles in the anisotropic conductive connection layer and a connection step of conducting through the conductive particles, Ri compression hardness at 30% compression deformation 150~400Kgf / mm ² der , The average particle density of the conductive particles is characterized in that 1000 to 50000 pieces / mm ^2.

A connection method according to the present invention that achieves the above-described object is a connection method in which a terminal provided on a flexible display and a terminal of an electronic component are connected by an anisotropic conductive connection layer, through the anisotropic conductive connection layer. Mounting the electronic component on the flexible display so that the terminal of the electronic component faces the terminal provided on the flexible display, and the terminal provided on the flexible display by pressing the electronic component against the flexible display And connecting the terminals of the electronic component with an anisotropic conductive connection layer and conducting the conductive particles through the conductive particles in the anisotropic conductive connection layer. The conductive particles are 30% compressed and deformed. compression hardness Ri 150～400Kgf / mm ² der, the average particle density of the conductive particles, be characterized by a 1,000 to 50,000 pieces / mm ² .

Anisotropic conductive film according to the present invention for achieving the above object, an anisotropic conductive film for connecting the pin of an electronic component provided in the flexible display, in the adhesive, 30% compressive deformation It is characterized by containing conductive particles having a compression hardness of 150 to 400 kgf / mm ² and an average particle density of 1000 to 50000 particles / mm ² .

The connection structure according to the present invention that achieves the above-described object connects the flexible display and the electronic component by interposing an anisotropic conductive connection layer between the terminal provided on the flexible display and the terminal of the electronic component. and a conductive the connection structure, the conductive particles of the anisotropic conductive layer, compressive hardness at 30% compression deformation Ri 150~400Kgf / mm ² der, average particle density 1000 to 50000 pieces characterized in that it is a / mm ^2.

According to the present invention, by setting the compression hardness at the time of 30% compression deformation of the conductive particles contained in the insulating adhesive of the anisotropic conductive connection material to 150 to 400 Kgf / mm ² , Even when pressure is applied when connecting electronic components, the conductive particles are deformed, the contact area between the conductive particles and the terminals of the flexible display is increased, and cracks can be prevented from entering the terminals of the flexible display. The display itself can be prevented from cracking or being destroyed.

It is sectional drawing of the film laminated body to which this invention is applied. It is a figure which shows the relationship of the compression displacement-load in calculation of the compression hardness at the time of 30% compressive deformation of electroconductive particle. It is a figure which shows the connection structure which connected the flexible display and the electronic component with the anisotropic conductive film, (A) is a top view of a connection structure, (B) is sectional drawing of a connection structure. It is sectional drawing which shows the connection part of the terminal of a flexible film, and the terminal of an electronic component. It is a top view of the connection structure which connected two IC chips and the flexible printed wiring board to the flexible display with the anisotropic conductive film.

Hereinafter, an anisotropic conductive connection material to which the present invention is applied, a connection structure, a method for manufacturing the connection structure, and a connection method will be described in detail with reference to the drawings. Note that the present invention is not limited to the following detailed description unless otherwise specified. The embodiment according to the present invention will be described in the following order.
1. 1. Anisotropic conductive connecting material Connection structure / Connection structure connection method / Connection method

<Anisotropic conductive connection material>
The anisotropic conductive connecting material is interposed between the terminal provided on the flexible display and the terminal of the electronic component, and connects the flexible display and the electronic component to make them conductive. Examples of such an anisotropic conductive connection material include a film-like anisotropic conductive film or a paste-like anisotropic conductive connection paste. In the present application, the anisotropic conductive film or the anisotropic conductive connection paste is defined as “anisotropic conductive connection material”. Hereinafter, an anisotropic conductive film will be described as an example.

  As shown in FIG. 1, the film laminate 1 is usually formed by laminating an anisotropic conductive film 3 serving as an anisotropic conductive connection layer on a release film 2 serving as a release substrate.

  The release film 2 is formed, for example, by applying a release agent such as silicone to PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methlpentene-1), PTFE (Polytetrafluoroethylene) or the like. .

  The anisotropic conductive film 3 is obtained by dispersing conductive particles 5 in an insulating adhesive (binder) 4 containing a film-forming resin, a thermosetting resin, a curing agent, and the like. The anisotropic conductive film 3 is formed on the release film 2 in a film shape.

  As the film-forming resin, a resin having an average molecular weight of about 10,000 to 80,000 is preferable. Examples of the film-forming resin include various resins such as an epoxy resin, a modified epoxy resin, a urethane resin, and a phenoxy resin. Among these, phenoxy resin is preferable from the viewpoint of film formation state, connection reliability, and the like. If the content of the film-forming resin is too small, a film will not be formed, and if it is too large, it will be difficult to eliminate the resin for electrical connection. Part by mass, preferably 40 to 70 parts by mass.

  As a hardening component, if it has fluidity | liquidity at normal temperature, it will not specifically limit, A commercially available epoxy resin and an acrylic resin are mentioned.

  The epoxy resin is not particularly limited and may be appropriately selected depending on the purpose. For example, naphthalene type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, bisphenol type epoxy resin, stilbene type epoxy resin, Phenolmethane type epoxy resin, phenol aralkyl type epoxy resin, naphthol type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin and the like can be mentioned. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as an acrylic resin, According to the objective, it can select suitably, For example, an acrylic compound, liquid acrylate, etc. are mentioned. Specifically, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, epoxy acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, dimethylol tricyclodecane diacrylate, tetramethylene glycol tetraacrylate, 2 -Hydroxy-1,3-diaacryloxypropane, 2,2-bis [4- (acryloxymethoxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy) phenyl] propane, dicyclopentenyl acrylate , Tricyclodecanyl acrylate, tris (acryloxyethyl) isocyanurate, urethane acrylate, epoxy acrylate and the like. These may be used alone or in combination of two or more.

  As the thermosetting resin, it is preferable to use an epoxy resin or an acrylic resin.

  Examples of the latent curing agent include various curing agents such as a heat curing type and a UV curing type. The latent curing agent does not normally react, but is activated by various triggers selected according to applications such as heat, light, and pressure, and starts the reaction. The activation method of the thermally activated latent curing agent includes a method of generating active species (cations and anions) by a dissociation reaction by heating, and the like. There are a method of dissolving and dissolving and starting a curing reaction, a method of starting a curing reaction by eluting a molecular sieve encapsulated type curing agent at a high temperature, an elution and curing method using microcapsules, and the like. Thermally active latent curing agents include imidazole, hydrazide, boron trifluoride-amine complexes, sulfonium salts, amine imides, polyamine salts, dicyandiamide, etc., and modified products thereof. The above mixture may be sufficient. Among these, a microcapsule type imidazole-based latent curing agent is preferable.

  The anisotropic conductive film 3 may contain a silane coupling agent. Although it does not specifically limit as a silane coupling agent, For example, an epoxy type, an amino type, a mercapto sulfide type, a ureido type etc. can be mentioned. By adding the silane coupling agent, connectivity at the interface between the organic material and the inorganic material can be improved.

As the electroconductive particle 5, the compression hardness (K value) at the time of 30% compression deformation is 150 to 400 Kgf / mm ² (1.50 to 4.00 GPa), preferably 150 to 350 Kgf / mm ² (1. 50 to 3.50 GPa). The index of hardness of the conductive particles 5 is calculated from the weight necessary for compressing and deforming 30% of the particle diameter in an unloaded state when one particle is weighted and deformed. Value. The 30% compressive deformation is a state in which when the conductive particles 5 are compressed in one direction, the particle size 2R (mm) of the conductive particles is deformed so as to be 30% shorter than the original particle size. This is a deformation state in which the particle size 2R of the conductive particles is 70% of the original particle size. The smaller the K value, the softer the particles.

  The compression hardness (K value) at the time of 30% compression deformation of the conductive particles 5 is calculated by the following equation (1).

  The K value is measured by, for example, the following measurement method. Specifically, first, conductive particles are dispersed on a steel plate having a smooth surface at room temperature. Next, one conductive particle is selected from the dispersed conductive particles. Then, this conductive property is obtained by pressing a smooth end face of a diamond cylinder having a diameter of 50 μm included in a micro compression tester (for example, PCT-200 type: manufactured by Shimadzu Corporation) against one selected conductive particle. Compress the sex particles. At this time, the compression load is electrically detected as an electromagnetic force, and the compression displacement is electrically detected as a displacement by the operating transformer. Here, the “compression displacement” refers to a value (mm) obtained by subtracting the length of the short diameter of the conductive particles after deformation from the particle diameter of the conductive particles before deformation. Then, another electroconductive particle on a steel plate is selected, and a compressive load and a compressive displacement are measured also about the selected electroconductive particle. For example, compressive deformation is measured for 10 conductive particles with different compressive loads.

  The relationship between the compression displacement and the load is expressed as shown in FIG. From the relationship shown in FIG. 2, the load value F (kgf) is calculated from the compression displacement S (mm) when the conductive particles are compressed by 30%. And the compression hardness K value at the time of 30% compression is calculated using Formula (1) from the load value F (kgf) and the compression displacement S (mm).

Since the compression hardness at the time of 30% compression deformation of the conductive particles 5 is 150 to 400 Kgf / mm ² , when the substantially spherical particles are pressed, they are deformed by a load, so that a flexible display as described later can be obtained. When the anisotropic conductive film 3 is interposed between the provided terminal and the terminal of the electronic component to connect and conduct the terminals, the terminal is deformed so that it is slightly crushed even if it is compressed. For this reason, the conductive particles 5 come into contact with the terminals of the flexible display without touching at points, reducing the pressure per unit area transmitted to the terminals and dispersing the local pressure applied to the terminals. It is possible to prevent the terminal from being cracked and the flexible display itself from being destroyed. If the K value of the conductive particles 5 is small and too soft, the conduction resistance value of the connecting portion is unstable, so that it is 150 Kgf / mm ² or more. By setting it as 150-400Kgf / mm < ² > or more, while being able to prevent the generation | occurrence | production of the crack of a terminal and the crack to flexible display itself, and a destruction, a conduction | electrical_connection resistance value can also be made low.

  Examples of the conductive particles 5 include particles of various metals and metal alloys such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, gold, metal oxide, carbon, graphite, glass, ceramic, plastic, and the like. The surface of the particles may be coated with a metal, or the surface of these particles may be further coated with an insulating thin film. When using a resin particle surface coated with metal, the resin particles include, for example, epoxy resin, phenol resin, acrylic resin, acrylonitrile / styrene (AS) resin, benzoguanamine resin, divinylbenzene resin, styrene resin, etc. Particles can be mentioned. The electroconductive particle 5 consists of these materials, and satisfy | fills the said K value.

  From the viewpoint of connection reliability, the average particle diameter of the conductive particles 5 is preferably 1 to 20 μm, more preferably 2 to 10 μm. By setting the average particle diameter of the conductive particles 5 in the range of 1 μm to 20 μm, electrical connection is possible even when compression deformation is caused by pressurization.

The average particle density of the conductive particles 5 in 4 insulating adhesive, from the viewpoint of connection reliability and insulation reliability, preferably 1,000 to 50,000 pieces / mm ^2, more preferably 3,000 to 30,000 pieces / mm ² It is.

  The film laminate 1 having such a structure is made of an anisotropic conductive composition in which the above-described insulating adhesive (binder) 4 is dissolved in a solvent such as toluene or ethyl acetate and the conductive particles 5 are dispersed. Produced by applying this anisotropic conductive composition on the release film 2 having peelability to a desired thickness, drying to remove the solvent, and forming the anisotropic conductive film 3 can do.

  In addition, the film laminated body 1 is not limited to the structure which formed the anisotropic conductive film 3 on such a peeling film 2, The insulating resin which consists only of the insulating adhesives 4 in the anisotropic conductive film 3, for example A layer (NCF: Non Conductive Film layer) may be laminated.

  Moreover, the film laminated body 1 is good also as a structure which provides a peeling film also on the surface side opposite to the surface where the peeling film 2 of the anisotropic conductive film 3 was laminated | stacked.

The anisotropic conductive film 3 of the film laminate 1 having the above-described configuration is pressurized when the compression hardness at the time of 30% compression deformation of the conductive particles 5 is 150 to 400 Kgf / mm ^2. The almost spherical particles are deformed by the load. For this reason, in this anisotropic conductive film 3, when it connects between the terminal provided in the flexible flexible display, and the terminal of an electronic component, and it connects, it deform | transforms so that it may be compressed and may be a little crushed. Because it comes in contact with the terminals of the flexible display by points instead of points, the contact area increases, so the pressure applied to the terminals is dispersed, cracks occur in the terminals, and cracks and damage to the flexible display itself Can be suppressed.

<Connecting structure / manufacturing method / connecting method of connecting structure>
Next, a connection method for conducting and connecting terminals of a flexible display and terminals of an electronic component using the anisotropic conductive film 3, a connection structure manufactured thereby, and a method for manufacturing the connection structure will be described. .

  In the connection structure 10 shown in FIG. 3, the flexible printed wiring board 13 is mechanically and electrically connected to the flexible display 11 so as to be electrically connected to the IC chip 12 and the outside as an electronic component for driving the flexible display 11. Are fixedly connected. The connection structure 10 includes a display unit 10a that displays an image and the like, and a mounting unit 10b on which the IC chip 12 and the flexible printed wiring board 13 are mechanically and electrically connected and mounted.

  The flexible display 11 includes two flexible films 14, a front plate and a back plate, and a display medium layer 15 such as a microcapsule layer or a liquid crystal layer is disposed between the two flexible films 14. The periphery of the layer 15 is sealed with a sealing portion 16 made of a sealing material. The flexible film 14 has a Young's modulus of 10 GPa or less, preferably 2 to 10 GPa, more preferably 3 to 5 GPa. The Young's modulus is a constant specific to a substance calculated from a strain per unit (deformation rate) generated when a substance is deformed by applying stress. If this Young's modulus is large, it is difficult to deform against stress, and if it is small, it is likely to deform. This flexible film 14 has a small Young's modulus and is easily deformed with respect to a load as compared with a glass substrate of about 72 GPa. Examples of the flexible film 14 include polyimide or polyethylene terephthalate. As shown in FIG. 4, the terminals 14 a provided on the flexible film 14 on the back plate and the terminals 12 a of the IC chip 12 and the terminals 13 a of the flexible printed wiring board 13 are electrically connected by conductive particles 5 that are compressed and deformed. Has been.

  The connection structure 10 can be manufactured by using the following connection method. First, the anisotropic conductive film 3 is interposed between the terminal 14a of the flexible film 14, the terminal 12a of the IC chip 12 and the terminal 13a of the flexible printed wiring board 13, and the terminals 14a of the flexible film 14 and the IC chip 12 are connected. A mounting step of mounting the IC chip 12 and the flexible printed wiring board 13 on the flexible film 14 is performed so that the terminals 12a and the terminals 13a of the flexible printed wiring board 13 face each other. Next, the IC chip 12 and the flexible printed wiring board 13 are pressed against the flexible film 14, and the terminals 14a provided on the flexible film 14 are different from the terminals 12a of the IC chip 12 and the terminals 13a of the flexible printed wiring board 13. The connection process of conducting through the conductive particles 5 in the anisotropic conductive film 3 and the connection with the anisotropic conductive film 3 is performed.

  About the manufacturing method of the connection structure 10, the case where the film laminated body 1 provided with the anisotropic conductive film 3 which contained the electroconductive particle 5 in the insulating adhesive 4 which used the thermoplastic resin as a hardening component is used is demonstrated, for example. To do. First, in the mounting process, the anisotropic conductive film 3 of the film laminate 1 is connected to the flexible film 14 at a position where the terminal 14 a of the flexible film 14 is connected to the terminal 12 a of the IC chip 12 and the terminal 13 a of the flexible printed wiring board 13. Then, the release film 2 is peeled off to make only the anisotropic conductive film 3, and then the anisotropic conductive film 3 is attached to the terminal 14a. This pasting is performed by heating at a temperature at which the thermosetting resin component contained in the anisotropic conductive film 3 is not cured, for example, while slightly pressing. Thereby, the anisotropic conductive film 3 is positioned and fixed on the terminal 14 a of the flexible film 14.

  Next, the IC chip 12 and the flexible printed wiring board 13 are mounted on the anisotropic conductive film 3. When the electronic component is mounted, the alignment state of the anisotropic conductive film 3 is confirmed, and if there is no misalignment or the like, the terminal 14a of the flexible film 14, the terminal 12a of the IC chip 12, and the flexible printed wiring board 13 are mounted. The IC chip 12 and the flexible printed wiring board 13 are mounted on the flexible film 14 via the anisotropic conductive film 3 so that the terminals 13a face each other.

  Next, the connection process of mechanically and electrically connecting the flexible film 14 of the flexible display 11 to the IC chip 12 and the flexible printed wiring board 13 is performed using a pressing head that can be heated and pressurized with the IC chip 12 and the flexible print. The IC chip 12 and the flexible printed wiring board 13 are heated and pressed against the flexible film 14 from the upper surface of the wiring board 13 to cure the anisotropic conductive film 3, and the terminals 14a of the flexible film 14 and the terminals of the IC chip 12 are cured. 12a and the terminal 13a of the flexible printed wiring board 13 are electrically connected through the conductive particles 5, and the flexible film 14, the IC chip 12 and the flexible printed wiring board 13 are mechanically connected by the insulating adhesive 4. Depending on the It can be IC chip 12 and the flexible printed circuit board 13 to the ray 11 to obtain the connection structure 10 connects.

  The condition of this connection process is that the heating temperature is a temperature equal to or higher than the curing temperature of the thermosetting resin contained in the anisotropic conductive film 3, and the anisotropic conductive film thermally melted from between the terminal 14a and the terminals 12a and 13a. 3 is excluded, and pressurization is performed at a pressure that can sandwich the conductive particles 5. Thereby, the flexible film 14, the IC chip 12, and the flexible printed wiring board 13 are electrically connected by the conductive particles 5 and mechanically connected by the insulating adhesive (binder) 4. Specific conditions for temperature and pressurization are a temperature of about 120 ° C. to 150 ° C. and a pressure of about 1 MPa to 5 MPa.

  In the connecting step, the IC chip 12 and the flexible printed wiring board 13 are pressed by the pressing head toward the flexible film 14, whereby the conductive particles 5 interposed therebetween are compressed and deformed, and the flexible film The 14 terminals 14a do not come into contact with each other but come into contact with each other, and the contact area with the terminal 14a increases. Thereby, in the connection process, the pressure per unit area transmitted from the conductive particles 5 to the terminal 14a can be reduced, the local pressure applied to the terminal 14a can be dispersed, and cracks can be prevented from occurring in the terminal 14a. The flexible film 14 can be prevented from cracking or being destroyed.

The manufacturing method of the connection structure 10 as described above is applied to the anisotropic conductive film 3 interposed between the terminal 14a of the flexible film 14, the terminal 12a of the IC chip 12, and the terminal 13a of the flexible printed wiring board 13. When the compressive hardness at the time of 30% compressive deformation of the contained conductive particles 5 is 150 to 400 Kgf / mm ² , when connecting the flexible film 14 and the electronic component, terminals are particularly scattered. When connecting to the IC chip 12, it is possible to prevent cracks from occurring in the terminals 14 a of the flexible film 14 and cracks or breakage of the flexible film 14 itself. Therefore, in the manufacturing method of the connection structure 10, no crack is generated in the terminal 14 a of the flexible film 14, the crack is not generated in the flexible film 14 itself, and the electronic component is formed on the flexible film 14 without being broken. Can be implemented.

  Therefore, the manufacturing method of the connection structure 10 is such that the mounting portion 10b is narrow when the mounting area for the electronic component exists near the display portion 10a having the display medium layer 15 of the flexible display 11 or immediately below the display portion 10a. Even if it is a simple mounting region, no cracks are generated in the terminals 14a of the flexible film 14, and no cracks are generated or broken in the flexible film 14 itself. Thus, it is possible to prevent the display medium layer 15 from affecting the display of an image or the like.

  The connection structure 10 described above has a configuration in which one IC chip 12 and a flexible printed wiring board 13 are mechanically and electrically connected to the flexible display 11, but the present invention is not limited to this, and as shown in FIG. The connection structure 20 may be sufficient. The connection structure 20 has a configuration in which two IC chips 12 and a flexible printed wiring board 13 are mechanically and electrically connected to the flexible film 14 of the flexible display 11 by the anisotropic conductive film 3. The connection structure 20 includes a display unit 20a that displays an image or the like using a display medium layer (not shown), and a mounting unit 20b that is mounted by mechanically and electrically connecting the IC chip 12 and the flexible printed wiring board 13 to each other. Have. In such a connection structure 20 as well, as in the connection structure 10 described above, the terminal 14a of the flexible film 14 is not cracked, and the flexible film 14 itself is not broken.

  In addition, the connection structures 10 and 20 described above do not require reinforcing treatment for preventing cracks on the terminals 14a of the flexible display 11, and the manufacturing cost is the same as the manufacturing process of the conventional flexible display 11. Can be prevented.

  The connection structures 10 and 20 are not limited to the flexible display described above, and may be ones in which an electronic component such as an IC chip 12 or a flexible printed wiring board 13 is connected to a flexible base material such as a flexible film. Good.

  Further, the electronic component is not limited to the IC chip 12 and the flexible printed wiring board 13 and may be other electronic components. For example, a semiconductor chip other than an IC chip such as an LSI (Large Scale Integration) chip, a semiconductor element such as a chip capacitor, a liquid crystal driving semiconductor mounting material (COF: Chip On Film), and the like can be given. Two or more electronic components may be mounted on the flexible display 11, and the mounting positions of the electronic components are not limited to those shown in FIGS. 4 and 5, and may be mounted directly below the display units 10a and 20a.

  As mentioned above, although this Embodiment was described, it cannot be overemphasized that this invention is not limited to the above-mentioned embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

  Next, specific examples of the present invention will be described based on the results of experiments actually performed, but the present invention is not limited to these examples.

<Preparation of anisotropic conductive film>
(Example 1 to Example 5)
In Examples 1 to 5, 30 parts by mass of a phenoxy resin (YP50, manufactured by Nippon Steel Chemical Co., Ltd.), 20 parts by mass of a liquid epoxy resin (EP-828, manufactured by Mitsubishi Chemical Co., Ltd.), and imidazole are used as film forming resins. System latent curing agent (Novacure 3941HP, manufactured by Asahi Kasei E-materials), 2 parts by mass of silane coupling agent (A-187, manufactured by Momentive Performance Materials), 10 parts by mass of conductive particles having a predetermined hardness, Toluene was added to a solid content of 50% to prepare an anisotropic conductive composition. Subsequently, the anisotropic conductive composition was applied onto a release substrate using a bar coater, and toluene was dried using an oven to prepare an anisotropic conductive film having a thickness of 20 μm.

  The conductive particles were produced by forming a core portion with a resin and applying nickel (Ni) plating or nickel gold (NiAu) plating to the core portion. Specifically, the resin particles in the core part are heated with uniform stirring at high speed by adding benzoisoperoxide as a polymerization initiator to a solution in which the mixing ratio of divinylbenzene, styrene, and butyl methacrylate is adjusted, A fine particle dispersion was obtained by carrying out a polymerization reaction. The fine particle dispersion was filtered and dried under reduced pressure to obtain a block body that was an aggregate of fine particles. Furthermore, this block was pulverized to obtain divinylbenzene resin particles having various hardnesses and an average particle diameter of 3.0 μm.

  The divinylbenzene resin particles obtained as described above were subjected to Ni plating or NiAu plating to produce conductive particles obtained by applying Ni plating or NiAu plating to the divinylbenzene resin particles.

  Conductive particles obtained by applying Ni plating to divinylbenzene resin particles were obtained by supporting a palladium catalyst on 5 g of 3 μm divinylbenzene resin particles by an immersion method. Next, an electroless nickel plating solution prepared from nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, triethanolamine and thallium nitrate (pH 12, plating solution temperature 50 ° C.) Electroless nickel plating was performed using nickel, and nickel-coated resin particles having nickel plating layers (metal layers) having various phosphorus contents formed on the surfaces were obtained as conductive particles (resin core Ni plating particles). The average particle diameter of the obtained conductive particles was in the range of 3 to 4 μm.

  Conductive particles obtained by applying NiAu plating to divinylbenzene resin particles were prepared by mixing 12 g of divinylbenzene resin particles with a solution of 10 g of sodium chloroaurate dissolved in 1000 mL of ion exchange water to prepare an aqueous suspension. . A gold plating bath was prepared by adding 15 g of ammonium thiosulfate, 80 g of ammonium sulfite, and 40 g of ammonium hydrogen phosphate to the obtained aqueous suspension. After 4 g of hydroxylamine was added to the gold plating bath obtained, the pH of the gold plating bath was adjusted to 9 using ammonia, and the bath temperature was maintained at 60 ° C. for about 15 to 20 minutes. Layer) was obtained as nickel-coated resin particles (resin core NiAu plating particles) formed on the surface. The average particle diameter of the obtained conductive particles was in the range of 3 to 4 μm.

  Table 1 shows the compression hardness at the time of 30% compression deformation of the conductive particles. As described above, the compressive hardness at 30% compressive deformation of the conductive particles is that the conductive particles are dispersed on a steel plate having a smooth surface at room temperature, and one of the dispersed conductive particles is electrically conductive. Particles were selected. Then, this conductive property is obtained by pressing a smooth end face of a diamond cylinder having a diameter of 50 μm included in a micro compression tester (for example, PCT-200 type: manufactured by Shimadzu Corporation) against one selected conductive particle. Sex particles were compressed. And the load value F (kgf) was computed from the compression displacement S (mm) at the time of 30% compression of electroconductive particle from the relationship shown in FIG. Then, the compression hardness K value at the time of 30% compression was calculated using Formula (1) from the calculated load value F (kgf) and compression displacement S (mm).

(Comparative Examples 1 to 3)
About Comparative Example 1- Comparative Example 3, except having produced electroconductive particle so that the compression hardness at the time of 30% compression of resin core Ni plating particle may become as shown in Table 1, it is the same as that of an Example. An anisotropic conductive film was produced.

<Crack generation test>
For the crack generation test, a flexible film of polyimide or polyethylene terephthalate (PET) having Young's modulus shown in Table 1 was used. On this flexible film, wiring was formed with a size of 20 mm × 40 mm × total thickness of 50.6 μm, PI / Al / ITO = 50 μm / 0.5 μm / 0.1 μm, and a pitch of 50 μm.

Next, the anisotropic conductive film produced is placed on the flexible film on which the wiring is formed, and the IC chip is placed on the anisotropic conductive film so that the terminals of the IC chip and the wiring face each other through the anisotropic conductive film. Arranged above. And it connected by heating and pressurizing on the conditions of temperature 200 degreeC and pressure 600kgf / cm < ² > with the press head from the upper surface of the IC chip, and produced the connection structure.

  And the generation | occurrence | production of the crack of wiring was confirmed visually. The rate of occurrence of cracks indicates the ratio of occurrence of cracks in 100 wirings. Table 1 and Table 2 show the crack occurrence rates.

<Test of conduction resistance>
In the test of the conduction resistance value, a flexible film and a flexible wiring board were connected as in the crack generation test, a connection structure was produced, and the conduction resistance was measured. The flexible wiring board has a size of 20 mm × 40 mm × 50.5 μm, PI / Al / ITO = 50 μm / 0.5 μm / 0.1 μm, and a conductive measurement wiring formed with a pitch of 50 μm for characteristic evaluation for measurement The element was used. The conduction resistance value after being allowed to stand for 125 hours in an 85 ° C./85% RH environment (after aging) was evaluated. The conduction resistance value was measured using a digital multimeter (trade name: Digital Multimeter 7561, manufactured by Yokogawa Electric Corporation) when a current of 1 mA was passed by the four-terminal method. When the conduction resistance value after aging is 10Ω or less, the resistance is low. Tables 1 and 2 show the measurement results of the conduction resistance values.

From the results shown in Tables 1 and 2, in Examples 1 to 5, cracks do not occur in the wiring, or even if cracks occur, the incidence is lower than in Comparative Examples 2 and 3, and the occurrence of cracks is suppressed. You can see that Therefore, from Examples 1 to 5, by causing the compression hardness at the time of 30% compression deformation of the conductive particles in the anisotropic conductive film to be within the range of 150 to 400 Kgf / mm ² , wiring cracks are generated. It can be seen that this can be suppressed.

Moreover, in Examples 1-5, the conduction | electrical_connection resistance value became low compared with the comparative example 1, and the conduction | electrical_connection resistance became low. Therefore, from Examples 1 to 5, by causing the compression hardness at the time of 30% compression deformation of the conductive particles in the anisotropic conductive film to be within the range of 150 to 400 Kgf / mm ² , wiring cracks are generated. It can be seen that the conduction resistance value can be lowered. Among the examples, in Example 2, no cracks were generated in the wiring, and the conduction resistance value was low.

In contrast to these examples, Comparative Example 1 has a compressive hardness at 30% compressive deformation of the conductive particles of 100 kgf / mm ² , and since the hardness is low, cracks in the wiring did not occur. Insufficient encroachment of the conductive particles into the surface occurred and a low conduction resistance value could not be obtained.

In Comparative Examples 2 and 3, since the compression hardness at the time of 30% compression deformation of the conductive particles is 500 kgf / mm ² and 720 kgf / mm ² , the hardness is high and the conduction resistance is low, but the wiring crack There has occurred. Since Comparative Example 3 was harder than Comparative Example 2, wiring cracks were more likely to occur.

  DESCRIPTION OF SYMBOLS 1 Film laminated body, 2 Release film, 3 Anisotropic conductive film, 4 Insulating adhesive, 5 Conductive particle, 10 Connection structure, 10a Display part, 10b Mounting part, 11 Flexible display, 12 IC chip, 12a terminal , 13 Flexible printed wiring board, 13a terminal, 14 flexible film, 15 display medium layer, 16 sealing part

Claims (16)

In a method for manufacturing a connection structure in which an anisotropic conductive connection layer is interposed between a terminal provided on a flexible display and a terminal of an electronic component, and the flexible display and the electronic component are connected and conducted.
A mounting step of mounting the electronic component on the flexible display so that the terminal of the electronic component faces the terminal provided on the flexible display via the anisotropic conductive connection layer;
The electronic component is pressurized against the flexible display, and the terminal provided on the flexible display and the terminal of the electronic component are connected by the anisotropic conductive connection layer and the conductivity in the anisotropic conductive connection layer. A connection step of conducting through the particles,
The conductive particles have a compression hardness at 30% compression deformation of 150 to 400 Kgf / mm ² , and the average particle density of the conductive particles is 1000 to 50000 particles / mm ^2. Manufacturing method of structure. The method for producing a connection structure according to claim 1, wherein an average particle density of the conductive particles is 3000 to 30000 particles / mm ² .   The method for producing a connection structure according to claim 1 or 2, wherein the flexible film used for the substrate of the flexible display has a Young's modulus of 2 to 10 GPa. 4. The method for manufacturing a connection structure according to claim 1, wherein the conductive particles have a compression hardness of 150 to 350 kgf / mm ² at 30% compression deformation. 5.   The method for producing a connection structure according to any one of claims 1 to 4, wherein the flexible film used for the substrate of the flexible display is polyimide or polyethylene terephthalate. In the connection method of connecting the terminal provided on the flexible display and the terminal of the electronic component by the anisotropic conductive connection layer,
A mounting step of mounting the electronic component on the flexible display so that the terminal of the electronic component faces the terminal provided on the flexible display via the anisotropic conductive connection layer;
The electronic component is pressurized against the flexible display, and the terminal provided on the flexible display and the terminal of the electronic component are connected by the anisotropic conductive connection layer and the conductivity in the anisotropic conductive connection layer. A connection step of conducting through the particles,
The conductive particles have a compression hardness at 30% compression deformation of 150 to 400 Kgf / mm ² , and the average particle density of the conductive particles is 1000 to 50000 particles / mm ^2. Method. The connection method according to claim 6, wherein an average particle density of the conductive particles is 3000 to 30000 particles / mm ² .   The connection method according to claim 6 or 7, wherein the flexible film used for the substrate of the flexible display has a Young's modulus of 2 to 10 GPa. 9. The connection method according to claim 6, wherein the conductive particles have a compression hardness of 150 to 350 kgf / mm ² when 30% compression deformation occurs.   The connection method according to claim 6, wherein the flexible film used for the flexible display is polyimide or polyethylene terephthalate. In the anisotropic conductive film that connects the terminals provided on the flexible display and the terminals of the electronic component,
The insulating adhesive contains conductive particles having a compression hardness at the time of 30% compression deformation of 150 to 400 Kgf / mm ² and an average particle density of 1000 to 50000 particles / mm ^2. Anisotropic conductive film. The anisotropic conductive film according to claim 11, wherein an average particle density of the conductive particles is 3000 to 30000 particles / mm ² . 13. The anisotropic conductive film according to claim 11, wherein the conductive particles have a compression hardness of 150 to 350 kgf / mm ² at 30% compression deformation.   The anisotropic conductive film according to claim 11, wherein the conductive particles are particles obtained by performing metal plating on a resin. A connection structure in which an anisotropic conductive connection layer is interposed between a terminal provided on a flexible display and a terminal of an electronic component, and the flexible display and the electronic component are connected and conducted,
The conductive particles in the anisotropic conductive connection layer have a compression hardness at 30% compression deformation of 150 to 400 Kgf / mm ² and an average particle density of 1000 to 50000 particles / mm ^2. Connection structure to be The connection structure according to claim 15 , wherein an average particle density of the conductive particles is 3000 to 30000 particles / mm ² .

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