JP2016178225A - Anisotropic conductive connection structure, anisotropic conductive connection method, and anisotropic conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive connection structure which is manufactured in a simpler process, achieves high reliability, and is new and improved, and to provide an anisotropic conductive connection method and an anisotropic conductive adhesive.SOLUTION: According to one aspect of the invention, in order to achieve the above object, an anisotropic conductive connection structure includes: a base substrate; a first terminal provided on the base substrate; a flexible substrate; a wiring pattern provided on the flexible substrate; an insulative protection film covering the wiring pattern; a second terminal connected with the wiring pattern; and an anisotropic conductive adhesive which makes anisotropic conductive connection between the first terminal and the second terminal. The insulative protection film is disposed at the outer side of the base substrate in a plane direction. The anisotropic conductive adhesive extends from the second terminal to a base substrate side end part of the insulative protection film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an anisotropic conductive connection structure, an anisotropic conductive connection method, and an anisotropic conductive adhesive.

  For example, in Patent Documents 1 and 2, in order to modularize a display panel, a terminal row on the base substrate (substrate constituting the display panel side) side and a terminal row on the flexible substrate side are made of anisotropic conductive adhesive. Anisotropic conductive connection is disclosed. In this technique, a terminal on the flexible substrate side is installed on a terminal row on the base substrate side via an anisotropic conductive adhesive. That is, the anisotropic conductive adhesive is sandwiched between the terminal row on the base substrate side and the terminal row on the flexible substrate side. Next, the terminal row on the base substrate side and the terminal row on the flexible substrate side are thermocompression bonded. Thus, the terminal row on the base substrate side and the terminal row on the flexible substrate side are anisotropically conductively connected.

  By the way, a wiring pattern connected to the terminal on the flexible substrate side is formed on the flexible substrate. For this reason, a wiring pattern may contact a board | substrate (especially corner | angular part of a board | substrate) at the time of bending of a flexible substrate, and a wiring pattern may disconnect. Therefore, in the techniques disclosed in Patent Documents 1 and 2, an insulating protective film (solder resist) is formed on the wiring pattern, and this insulating protective film is formed up to the region on the base substrate. This prevents the wiring pattern from contacting the base substrate when the flexible substrate is bent.

JP 2002-358026 A JP 2009-135388 A

  However, in the techniques disclosed in Patent Documents 1 and 2, when the base substrate side terminal row and the flexible substrate side terminal row are thermocompression bonded, the insulating protective film may come into contact with the base substrate. It was. In this case, sufficient pressure is not applied between the terminal row on the base substrate side and the terminal row on the flexible substrate side. In other words, when the insulating protective film comes into contact with the base substrate, the insulating protective film hinders the proximity of the terminal row on the base substrate side and the terminal row on the flexible substrate side. For this reason, connection failure may occur between the terminal row on the base substrate side and the terminal row on the flexible substrate side.

  Furthermore, when thermocompression bonding the terminal row on the base board side and the terminal row on the flexible board side, the anisotropic conductive adhesive not involved in the anisotropic conductive connection is placed in the gap between the terminals constituting each terminal row. It flows and then flows outside each terminal row. Here, when the insulating protective film comes into contact with the base substrate, the anisotropic conductive adhesive that tends to flow to the outside through the gap between the terminals on the base substrate side is blocked by the insulating protective film. In this case, many anisotropic conductive adhesives remain between the terminals on the base substrate side. That is, a large amount of conductive particles constituting the anisotropic conductive adhesive stay between the terminals on the base substrate side. These conductive particles sometimes cause the terminals on the base substrate side to pass through (that is, the terminals are short-circuited). As described above, in the technologies disclosed in Patent Documents 1 and 2, the reliability of the structure in which the terminal row on the board side and the terminal row on the flexible board side are anisotropically connected, that is, the anisotropic conductive connection structure is high. There was a problem of being low.

  As a technique for solving the above problem, a technique has been proposed in which an insulating protective film is disposed on the outside in the surface direction of the substrate (direction perpendicular to the thickness direction of the substrate). However, in this technique, a gap is formed between the insulating protective film and the anisotropic conductive adhesive layer (adhesive layer that connects the terminal row on the board side and the terminal row on the flexible board side in an anisotropic conductive manner). There was a case. In this case, the wiring pattern existing in the gap is exposed. As described above, when a part of the wiring pattern is exposed, foreign matter may adhere to this part and the wiring pattern may be short-circuited. Further, when the flexible substrate is bent, the exposed portion of the wiring pattern may break. Therefore, even with this technique, the reliability of the anisotropic conductive connection structure cannot be improved.

  Therefore, a technique for protecting the exposed portion of the wiring pattern with a sealant has been proposed. However, this technique requires a separate step of covering the exposed portion of the wiring pattern with a sealant. In this step, after the terminal row on the substrate side and the terminal row on the flexible substrate side are thermocompression bonded, the connection structure of the base substrate and the flexible substrate is turned over. As a result, the exposed portion of the wiring pattern is directed upward. And a sealing agent is inject | poured into the exposed part of the said wiring pattern, and light is irradiated to a sealing agent from a light source. Thereby, a sealing agent is hardened. As described above, since the process of covering the exposed portion of the wiring pattern with the sealant is very laborious, the labor required for bonding the display panel and the flexible substrate increases.

  Accordingly, the present invention has been made in view of the above problems, and the object of the present invention is a new and improved difference that can be manufactured by a simpler process and has high reliability. An object is to provide a anisotropic conductive connection structure, an anisotropic conductive connection method, and an anisotropic conductive adhesive.

  In order to solve the above problems, according to an aspect of the present invention, there is provided a base substrate, a first terminal provided on the base substrate, a flexible substrate, a wiring pattern provided on the flexible substrate, and a wiring pattern. An insulating protective film for covering, a second terminal connected to the wiring pattern, a first terminal, and an anisotropic conductive adhesive layer for anisotropically connecting the second terminal, and insulating The anisotropic protective film is disposed on the outer side in the surface direction of the base substrate, and the anisotropic conductive adhesive layer extends from the second terminal to the end of the insulating protective film on the base substrate side. A structure is provided.

  Here, the distance from the end of the base substrate on the insulating protective film side to the end of the insulating protective film on the base substrate side may be 0.3 mm or less.

  Furthermore, the 30 ° C. elastic modulus of the anisotropic conductive adhesive layer may be 4.0 GPa or less.

  According to another aspect of the present invention, a step of preparing a base substrate provided with a first terminal, a wiring pattern, an insulating protective film covering the wiring pattern, and a second terminal connected to the wiring pattern A step of preparing a flexible substrate provided with: an uncured polymerizable compound; a thermosetting initiator; and an anisotropic conductive adhesive including conductive particles; a first terminal; By sandwiching the anisotropic conductive adhesive with the second terminal and disposing the insulating protective film on the outer side in the surface direction of the base substrate, and thermocompression bonding the base substrate and the flexible substrate, the first And anisotropically connecting the second terminal and the second terminal, and flowing an anisotropic conductive adhesive to the end of the insulating protective film on the base substrate side. Is provided. The order of the steps for preparing each material is not limited.

  Here, the anisotropic conductive adhesive further includes a photocuring initiator, and after flowing the anisotropic conductive adhesive to the end portion of the insulating protective film on the base substrate side, the anisotropic conductive adhesive is moved outwardly in the surface direction of the base substrate. You may irradiate light to the anisotropic conductive adhesive which flowed.

  Further, the flexible substrate is disposed above the base substrate, and the anisotropic conductive adhesive may be irradiated with light from below the anisotropic conductive adhesive.

  The anisotropic conductive adhesive is an anisotropic conductive film, and the thickness of the anisotropic conductive film is at least 1.4 times the total height of the first terminal and the second terminal. May be.

  According to another aspect of the present invention, the composition includes an uncured polymerizable compound, a thermosetting initiator, and conductive particles, and has a minimum melt viscosity of 100 to 1000 Pa · s in an uncured state and is completely cured. An anisotropic conductive adhesive having a later 30 ° C. elastic modulus of 4.0 GPa or less is provided.

  Here, the anisotropic conductive adhesive may further contain a photocuring initiator.

  According to the above aspect of the present invention, the insulating protective film is disposed on the outer side in the surface direction of the base substrate. Therefore, since the insulating protective film does not hinder the proximity of the first terminal and the second terminal, poor connection between the first terminal and the second terminal hardly occurs. Furthermore, the anisotropic conductive adhesive that has flowed into the gap between the first terminals can smoothly flow to the outside of the first terminal row. Therefore, it becomes difficult for the first terminals to short-circuit each other. Therefore, the reliability of the anisotropic conductive connection structure is improved.

  Furthermore, in the above aspect of the present invention, the adhesive layer reaches the insulating protective film. For this reason, no gap is formed between the adhesive layer and the insulating protective film. Therefore, since the exposed portion of the wiring pattern is not formed, a step of sealing the exposed portion of the wiring pattern with the sealant is not necessary. For this reason, an anisotropic conductive connection structure can be produced by a simpler process.

  As described above, according to the present invention, an anisotropic conductive connection structure having high reliability can be manufactured by a simpler process.

It is a sectional side view which shows typically the structure of the anisotropic conductive connection structure which concerns on embodiment of this invention. It is a sectional side view which shows a part of manufacturing process of an anisotropic conductive connection structure. It is a sectional side view which shows a part of manufacturing process of an anisotropic conductive connection structure. It is a perspective view for demonstrating the measuring method of the resin flow amount. It is a top view for demonstrating the measuring method of the resin flow amount. It is a top view for demonstrating the measuring method of the resin flow amount. It is a sectional side view which shows typically the example of the aspect in which the clearance gap is formed between the anisotropic conductive adhesive layer and the insulating protective film. It is a sectional side view which shows typically the other example of the aspect by which the clearance gap is formed between the anisotropic conductive adhesive layer and the insulating protective 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. Configuration of Anisotropic Conductive Connection Structure>
First, based on FIG. 1, the structure of the anisotropic conductive connection structure 1 which concerns on this embodiment is demonstrated.

  The anisotropic conductive connection structure 1 (hereinafter, also simply referred to as “connection structure 1”) includes a base substrate 10, a first terminal 11, a first wiring pattern 12, a flexible substrate 20, a second terminal 21, A second wiring pattern 22, an insulating protective film 30, and an anisotropic conductive adhesive layer 40 (hereinafter simply referred to as “adhesive layer 40”) are provided.

  The base substrate 10 is, for example, a glass substrate constituting a display panel, but is not particularly limited as long as it is a substrate that is anisotropically conductively connected to the flexible substrate 20. Further, the thickness of the base substrate 10 is not particularly limited, but in this embodiment, the adhesive layer 40 is formed on the back surface of the base substrate 10 (the first terminal row and the wiring pattern 12) even if the thickness is 0.7 mm or less. The surface on the side opposite to the surface on which the is formed is difficult to wrap around. Further, a chamfered portion 10 b may be formed at the end portion 10 a of the base substrate 10.

  A plurality of first terminals 11 are provided on the end portion 10 a of the base substrate 10. The first terminals 11 are parallel to each other, and a plurality of first terminals 11 form a first terminal row. In addition, when the chamfered part 10b is formed on the edge part 10a, the 1st terminal 11 should just be formed in the center side (inner side) of the base substrate 10 rather than the chamfered part 10b. Each of the first terminals 11 is anisotropically conductively connected to the second terminal 21.

  The material which comprises the 1st terminal 11 will not be restrict | limited especially if it has electroconductivity. Examples of the material constituting the first terminal 11 include metals such as aluminum, silver, nickel, copper, and gold, indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide, conductive tin oxide, Examples thereof include conductive metal oxides such as antimony tin oxide (ATO) and conductive zinc oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene. The metal constituting the first terminal 11 may be plated with various metals (for example, gold, tin, etc.). When the base substrate 10 is a display panel substrate, it is necessary to ensure the visibility of an image displayed on the display panel. Therefore, in this case, the first terminal 11 is preferably formed of a transparent conductive material (ITO, IZO, etc.).

  The first wiring pattern 12 is a wiring pattern extending from the first terminal 11 and is provided on the base substrate 10. The material constituting the first wiring pattern 12 may be the same as that of the first terminal 11.

  The flexible substrate 20 is a substrate formed of a material having high flexibility and flexibility. The material which comprises the flexible substrate 20 is not restrict | limited in particular, The material applied to a well-known flexible substrate is applicable also to this embodiment. Examples of the material constituting the flexible substrate 20 include thinned metal or glass in addition to resins such as polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyethylene, polycarbonate, polyimide, and acrylic resin. . When the base substrate 10 is a display panel substrate, it is necessary to ensure the visibility of an image displayed on the display panel. Therefore, in this case, the flexible substrate 20 is preferably formed of a transparent resin having a high visible light transmittance.

  A plurality of second terminals 21 are provided on the end portion 20 a of the flexible substrate 20. The second terminals 21 are parallel to each other, and a plurality of second terminals 21 form a second terminal row. Each of the second terminals 21 is anisotropically conductively connected to the first terminal 11. That is, the first terminal row and the second terminal row are anisotropically conductively connected. The material constituting the second terminal 21 may be the same as that of the first terminal 11.

  The second wiring pattern 22 is a wiring pattern extending from the second terminal row, and is provided on the base substrate 10. The material constituting the second wiring pattern 22 may be the same as that of the first terminal 11.

  The insulating protective film 30 is a film that covers the wiring pattern 22. The insulating protective film 30 is an insulating film and protects the wiring pattern 22. The insulating protective film 30 is also called a solder resist. The material which comprises the insulating protective film 30 is not restrict | limited in particular, If it is the soldering resist material applied to the conventional flexible substrate, it can apply suitably also to this embodiment.

  In the present embodiment, the insulating protective film 30 is disposed outside the surface direction of the base substrate 10 (direction perpendicular to the thickness direction of the base substrate 10). As described above, when the insulating protective film 30 is disposed on the base substrate 10, problems such as poor connection between the first terminal row and the second terminal row and a short circuit between the first terminals 11 may occur. Because. The distance L from the end portion 10a of the base substrate 10 (end portion on the insulating protective film 30 side) to the end portion 30a of the insulating protective film 30 on the base substrate 10 side is not particularly limited. In this embodiment, the anisotropic conductive adhesive is caused to flow to the insulating protective film 30 when the first terminal row and the second terminal row are thermocompression bonded. Therefore, the minimum melt viscosity of the anisotropic conductive adhesive may be adjusted according to the distance L. The smaller the minimum melt viscosity, the greater the amount of anisotropic conductive adhesive flowing. However, the distance L is preferably 0.3 mm or less. In this case, the anisotropic conductive adhesive can flow more reliably to the insulating protective film 30 during the thermocompression bonding between the first terminal row and the second terminal row. This is more noticeable when the distance L is greater than zero. When the thickness of the base substrate 10 is excessively thin, for example, 0.2 μm or less, the distance L may be 0 or less, and the range in which the end 30a of the insulating protective film 30 is disposed on the chamfered portion 10b. 0 to -0.2 mm is preferable. This is to prevent the adhesive layer 40 from entering the back surface of the base substrate 10. More specifically, a negative value of L means that the end portion 30 a of the insulating protective film 30 on the base substrate 10 side is disposed on the base substrate 10. However, even in this case, if the end portion 30a of the insulating protective film 30 is disposed on the chamfered portion 10b of the base substrate 10, the first terminal row and the second terminal row are thermocompression bonded. At this time, it becomes difficult for the insulating protective film 30 to contact the base substrate 10. Moreover, the insulating protective film 30 becomes difficult to inhibit the flow of the anisotropic conductive adhesive during thermocompression bonding.

  The adhesive layer 40 is obtained by curing an anisotropic conductive adhesive described later. The adhesive layer 40 makes an anisotropic conductive connection between the first terminal row and the second terminal row. Furthermore, the adhesive layer 40 extends from the second terminal row to the end 30a of the insulating protective film 30 on the base substrate side. For this reason, in this embodiment, no gap is formed between the adhesive layer 40 and the insulating protective film 30. That is, a portion of the wiring pattern 22 that is not covered with the insulating protective film 30 is protected by the adhesive layer 40. The adhesive layer 40 only needs to extend to the insulating protective film 30, but preferably covers the end 30 a of the insulating protective film 30. In this case, the adhesive layer 40 can more reliably protect the portion not covered with the insulating protective film 30.

  The physical properties of the adhesive layer 40 other than those described above are not particularly limited, but the 30 ° C. elastic modulus is preferably 4.0 GPa or less. In the present embodiment, since the adhesive layer 40 is formed to the outside in the surface direction of the base substrate 10, the adhesive layer 40 is also bent when the flexible substrate 20 is bent. Therefore, if the 30 ° C. elastic modulus is 4.0 GPa or less, the flexible substrate 20 can be easily bent. In addition, the material which comprises the adhesive bond layer 40 is demonstrated in detail in the term of the anisotropic conductive adhesive mentioned later.

<2. Anisotropic conductive adhesive>
The adhesive layer 40 is obtained by curing an anisotropic conductive adhesive. Therefore, here, the anisotropic conductive adhesive will be described. The anisotropic conductive adhesive includes at least a polymerizable compound, a thermosetting initiator, and conductive particles.

  The polymerizable compound is a resin that cures together with a thermosetting initiator or a photocuring initiator. The cured polymerizable compound adheres the first terminal row and the second terminal row in the adhesive layer 40 and holds the conductive particles in the adhesive layer 40. The polymerizable compound is not particularly limited as long as it satisfies the physical properties described below. 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 acrylic polymerizable compounds 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 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.

  The conductive particles are a material that anisotropically conductively connects the first terminal row and the second terminal row within the adhesive layer 40. Specifically, the conductive particles sandwiched between the first terminal row and the second terminal row in the adhesive layer 40 make the first terminal row and the second terminal row conductive. On the other hand, other conductive particles (for example, conductive particles that have entered the gap between the first terminals 11, conductive particles that have entered the gap between the second terminals 21, etc.) are dispersed in the adhesive layer 40. Are not connected to each other. Therefore, the conductive particles make the first terminal row and the second terminal row conductive while maintaining the insulation between the first terminals 11 and the second terminals 21 in the adhesive layer 40. Can do. That is, the conductive particles make an anisotropic conductive connection between the first terminal row and the second terminal row in the adhesive layer 40.

  The kind of conductive particles is not particularly limited. Examples of the conductive particles include metal particles and metal-coated resin particles. Examples of the metal particles include metal particles such as nickel, cobalt, copper, silver, gold, or palladium. Examples of the metal-coated resin particles include nickel, copper, gold, or palladium on the surface of core resin particles such as styrene-divinylbenzene copolymer, benzoguanamine resin, cross-linked polystyrene resin, acrylic resin, or styrene-silica composite resin. And particles coated with a metal such as On the surface of the conductive particles, a gold or palladium thin film, or an insulating resin thin film that is thin enough to be destroyed during pressure bonding may be formed.

  The anisotropic conductive adhesive of this embodiment preferably further contains a photocuring initiator. Although details will be described later, in this embodiment, the anisotropic conductive adhesive is sandwiched between the first terminal row and the second terminal row, and then the first terminal using a heating and pressing member such as a heat tool. The row and the second terminal row are thermocompression bonded. At this time, a part of the anisotropic conductive adhesive flows from the first terminal row and the second terminal row to the outside in the surface direction of the base substrate 10 and reaches the insulating protective film 30. A sufficient amount of heat is supplied from the heating and pressing member to the anisotropic conductive adhesive existing between the first terminal row and the second terminal row. For this reason, the anisotropic conductive adhesive existing between the first terminal row and the second terminal row can be cured only by the amount of heat from the heating and pressing member. However, there is a possibility that the amount of heat from the heating and pressing member is not sufficiently supplied to the anisotropic conductive adhesive flowing from the first terminal row and the second terminal row to the outside in the surface direction of the base substrate 10. For this reason, the anisotropic conductive adhesive that has flowed from the first terminal row and the second terminal row to the outside in the surface direction of the base substrate 10 may not be sufficiently cured only by the amount of heat from the heating and pressing member. . Therefore, it is preferable that the anisotropic conductive adhesive of this embodiment further contains a photocuring initiator. In this case, the anisotropic conductive adhesive is sufficiently cured by irradiating the anisotropic conductive adhesive flowing from the first terminal row and the second terminal row to the outside in the surface direction of the base substrate 10. Can be made.

  In addition, the kind in particular of photocuring initiator is not restrict | limited. 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. In this embodiment, an appropriate photocuring initiator may be selected depending on the polymerizable compound. When the anisotropic conductive adhesive that has flowed from the first terminal row and the second terminal row to the outside in the surface direction of the base substrate 10 is sufficiently cured only by the amount of heat from the heating and pressing member, the photocuring initiator is different. It may not be added to the isotropic conductive adhesive.

  In addition to the above components, the anisotropic conductive adhesive may include a film-forming resin, various additives, and the like. The film-forming resin is added to the anisotropic conductive adhesive when the anisotropic conductive adhesive is desired to have a film shape. The type of film forming resin is not particularly limited as long as it satisfies the characteristics described later. 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.

  Examples of additives that can be added to the anisotropic conductive adhesive 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. When these silane coupling agents are added to the anisotropic conductive adhesive, adhesion to an inorganic substrate such as a glass substrate can be improved.

  The inorganic filler is an additive for adjusting the fluidity and film strength of the anisotropic conductive adhesive, particularly the minimum melt viscosity described later. 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 minimum melt viscosity of the anisotropic conductive adhesive is 100 to 1000 Pa · s. When this condition is satisfied, the anisotropic conductive adhesive can reach the insulating protective film 30 when the first terminal row and the second terminal row are thermocompression bonded. Here, the minimum melt viscosity of the anisotropic conductive adhesive can be adjusted by changing the type of the polymerizable compound, but can also be adjusted by the amount of the inorganic filler added. There exists a tendency for the minimum melt viscosity of an anisotropic conductive adhesive to become small, so that there are few addition amounts of an inorganic filler. Therefore, the minimum melt viscosity of the anisotropic conductive adhesive can be easily adjusted by adjusting the addition amount of the inorganic filler. The minimum melt viscosity of the anisotropic conductive adhesive is preferably 100 to 800 Pa · s, and more preferably 200 to 600 Pa · s. When these conditions are satisfied, the anisotropic conductive adhesive can reach the insulating protective film 30 more reliably.

  Moreover, it is preferable that the 30 degreeC elastic modulus after complete hardening of an anisotropic conductive adhesive is 4.0 GPa or less. As described above, in the present embodiment, the anisotropic conductive adhesive after complete curing, that is, the adhesive layer 40 is formed to the outside in the surface direction of the base substrate 10, so that the adhesive layer is folded when the flexible substrate 20 is bent. 40 is also folded. Therefore, if the 30 ° C. elastic modulus is 4.0 GPa or less, the flexible substrate 20 can be easily bent. If the 30 ° C. elastic modulus is 4.0 GPa or less, the adhesive layer 40 is difficult to peel off when the flexible substrate 20 is bent. That is, the adhesive strength of the adhesive layer 40 is sufficiently increased. The 30 degreeC elasticity modulus of an anisotropic conductive adhesive can be adjusted by changing the kind and compounding quantity of film forming resin and a polymeric compound, for example.

  Further, the resin flow amount of the anisotropic conductive adhesive is preferably 1.3 to 2.5, and more preferably 1.5 to 2.3. When the value of the resin flow amount is a value within these ranges, the anisotropic conductive adhesive can reach the insulating protective film 30 more reliably.

  The anisotropic conductive adhesive may be a paste-like anisotropic conductive paste, or may be an anisotropic conductive film formed into a film by further containing a film-forming resin. Here, when using an anisotropic conductive film as an anisotropic conductive adhesive, it is desirable that the anisotropic conductive film is provided on a release film. The release film is made of, for example, PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methylpentene-1), PTFE (Polytetrafluoroethylene), or other release agent such as silicone. The release film prevents the anisotropic conductive film from drying and maintains the shape of the anisotropic conductive film.

<3. Anisotropic conductive connection method>
Next, the manufacturing method of the connection structure 1, that is, the anisotropic conductive connection method will be described with reference to FIGS. Here, the manufacturing method will be described by taking as an example a case where an anisotropic conductive film containing a photocuring initiator is used as the anisotropic conductive adhesive. First, the base substrate 10 provided with the first terminal row is prepared. Furthermore, the flexible substrate 20 provided with the second terminal row, the wiring pattern 22, and the insulating protective film 30 is prepared. Furthermore, an anisotropic conductive film 50 having the above-described characteristics is prepared.

  Next, as shown in FIG. 2, the anisotropic conductive film 50 is sandwiched between the first terminal row and the second terminal row. For example, the base substrate 10 is installed on some sample stage. Next, the anisotropic conductive film 50 is placed on the first terminal row and temporarily crimped. Here, the temporary pressure bonding is performed, for example, by pressing a heating and pressing member against the anisotropic conductive film 50. The temperature at the time of temporary pressure bonding is lower than the temperature at the time of final pressure bonding, and is set to a temperature at which the anisotropic conductive film 50 is not cured. Next, the flexible substrate 20 is installed on the base substrate 10 so that the second terminal row faces the first terminal row. Here, the insulating protective film 30 is disposed on the outer side in the surface direction of the base substrate 10. Moreover, it is preferable that the thickness of the anisotropic conductive film 50 is 1.4 times or more of the total height of the first terminal row and the second terminal row. In this case, the anisotropic conductive film 50 can flow to the insulating protective film 30 more reliably.

  Next, the first terminal row and the second terminal row are subjected to thermocompression bonding (main compression bonding). For example, a heating and pressing member 100 capable of heating and pressing the entire area of the first terminal row and the second terminal row is prepared, and the heating and pressing member 100 is pressed against the flexible substrate 20 from above the flexible substrate 20. The pressing position by the heating and pressing member 100 is directly above the first terminal row and the second terminal row. What is necessary is just to adjust suitably the pressurizing force of the heating pressurization member 100, temperature, and pressurization time with the material of the anisotropic conductive film 50, etc. FIG. That is, these parameters may be adjusted so that the anisotropic conductive film 50 flows to the insulating protective film 30 and is cured in that state.

  Thereby, a part of the anisotropic conductive film 50 remains between the first terminal row and the second terminal row, and the rest is a gap between the first terminals 11 and a gap between the second terminals 21. Or flow outside the first terminal row and the second terminal row. As shown in FIG. 3, the anisotropic conductive film 50 after flowing is divided into an anisotropic conductive connecting portion 40a, a first flowing portion 40b, and a second flowing portion 40c. The anisotropic conductive connection portion 40a remains between the first terminal row and the second terminal row and conducts them. The first flowing portion 40b is a portion that flows inward in the plane direction from the first terminal row and the second terminal row. The second flow portion 40 c is a portion that flows outward in the surface direction from the first terminal row and the second terminal row and reaches the insulating protective film 30. The first fluid portion 40b and the second fluid portion 40c maintain insulation. Therefore, the first terminal row and the second terminal row are anisotropically conductively connected by the main pressure bonding.

  The anisotropic conductive connection portion 40 a and the first flow portion 40 b are sufficiently cured by the amount of heat applied from the heating and pressing member 100. However, the second fluid portion 40c may not be sufficiently cured only by the amount of heat given from the heating and pressing member 100. Therefore, as shown in FIG. 3, light (for example, UV light) is irradiated from below the flow portion 40c. The light intensity and the irradiation time may be values that sufficiently cure the second fluid portion 40c. Thereby, the anisotropic conductive film 50 can be hardened | cured completely. In addition, hardening by light irradiation may be performed after time passes from thermocompression bonding. The cured anisotropic conductive film 50 becomes the adhesive layer 40 described above.

  As described above, according to the present embodiment, the insulating protective film 30 of the connection structure 1 is disposed on the outer side in the surface direction of the base substrate 10. Therefore, since the insulating protective film 30 does not hinder the proximity of the first terminal row and the second terminal row, poor connection between the first terminal row and the second terminal row hardly occurs. Furthermore, the anisotropic conductive adhesive that has flowed into the gap between the first terminals 11 can flow smoothly to the outside of the first terminal row. Therefore, it becomes difficult for the first terminals 11 to short-circuit each other. Therefore, the reliability of the connection structure 1 is improved.

  Furthermore, in the present embodiment, the adhesive layer 40 reaches the insulating protective film 30. For this reason, no gap is formed between the adhesive layer 40 and the insulating protective film 30. Therefore, since the exposed portion of the wiring pattern 22 is not formed, a process of sealing the exposed portion of the wiring pattern with the sealant becomes unnecessary. For this reason, the connection structure 1 can be produced by a simpler process.

  In addition, in the technique which produces a connection structure using a sealing agent, a connection structure is produced using a manufacturing apparatus provided with a heating and pressing member and a light source. On the other hand, a heating and pressing member and a light source are also used in this embodiment. Therefore, the conventional manufacturing apparatus can be used as the manufacturing apparatus of the present embodiment almost as it is (for example, only by changing the installation position of the light source).

(Preparation of anisotropic conductive film)
Example 1
Phenoxy resin (product name: PKHC, manufactured by Sakai Kogyo Co., Ltd.) 50 parts by mass, urethane acrylic oligomer (product name: EB-600, manufactured by Daicel Cytec Co., Ltd.) 40 parts by mass, acrylic monomer (product name: A-DCP, manufactured by Shin-Nakamura Chemical Co., Ltd.) ) 5 parts by mass, 2 parts by mass of a silane coupling agent (product name: KBM-503, manufactured by Shin-Etsu Silicone), 5 parts by mass of Perhexa C (manufactured by NOF Corporation) as a thermosetting initiator, and benzophenone 5 as a photocuring initiator An adhesive composition was prepared by mixing 6 parts by mass of 6 parts by mass and conductive particles (product name: AUL704, particle size 4 μm, manufactured by Sekisui Chemical Co., Ltd.). Then, an adhesive composition was applied to a separately prepared release-treated PET film having a thickness of 38 μm with a bar coater and dried to obtain an anisotropic conductive film having a thickness of 20 μm.

(Example 2)
The thickness of the adhesive composition prepared in Example 1 was the same as in Example 1 except that 4 parts by mass of hydrophobic silica (product name: AEROSIL972, manufactured by EVONIK) was added as a thickener. A 20 μm anisotropic conductive film was obtained.

(Example 3)
Phenoxy resin (product name: PKHC, manufactured by Sakai Kogyo Co., Ltd.) 50 parts by mass, urethane acrylic oligomer (product name: EB-600, manufactured by Daicel Cytec Co., Ltd.) 35 parts by mass, acrylic monomer (product name: A-DCP, manufactured by Shin-Nakamura Chemical Co., Ltd.) ) 15 parts by mass, 2 parts by mass of a silane coupling agent (product name: KBM-503, manufactured by Shin-Etsu Silicone), 5 parts by mass of Perhexa C (manufactured by NOF Corporation) as a thermosetting initiator, and 5 mass of benzophenone as a photocuring initiator Part and conductive particles (product name: AUL704, particle size 4 μm, manufactured by Sekisui Chemical Co., Ltd.) 6 parts by mass were mixed to obtain an adhesive composition. Then, an adhesive composition was applied to a separately prepared release-treated PET film having a thickness of 38 μm with a bar coater and dried to obtain an anisotropic conductive film having a thickness of 20 μm.

Example 4
An anisotropic conductive film having a thickness of 20 μm was obtained by performing the same treatment as in Example 1 except that the photocurable initiator benzophenone was removed from the adhesive composition prepared in Example 1.

(Example 5)
By performing the same treatment as in Example 1 except that 8 parts by mass of hydrophobic silica (product name: AEROSIL972, manufactured by EVONIK) was added to the adhesive composition prepared in Example 1 as a thickener. An anisotropic conductive film having a thickness of 20 μm was obtained.

(Example 6)
50 parts by mass of phenoxy resin (product name: PKFE, manufactured by Sakai Kogyo Co., Ltd.), 25 parts by mass of urethane acrylic oligomer (product name: EB-600, manufactured by Daicel-Cytec), acrylic monomer (product name: A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) ) 25 parts by mass, 2 parts by mass of a silane coupling agent (product name: KBM-503, manufactured by Shin-Etsu Silicone), 5 parts by mass of Perhexa C (manufactured by NOF Corporation) as a thermosetting initiator, and 5 mass of benzophenone as a photocuring initiator Part and conductive particles (product name: AUL704, particle size: 4 μm, manufactured by Sekisui Chemical Co., Ltd.) were mixed to prepare an adhesive composition. Then, an adhesive composition was applied to a separately prepared release-treated PET film having a thickness of 38 μm with a bar coater and dried to obtain an anisotropic conductive film having a thickness of 20 μm.

(Comparative Example 1)
By performing the same treatment as in Example 1 except that 12 parts by mass of hydrophobic silica (product name: AEROSIL972, manufactured by EVONIK) was added to the adhesive composition prepared in Example 1 as a thickener. An anisotropic conductive film having a thickness of 20 μm was obtained.

(Comparative Example 2)
Epoxy resin (product name: jER4004, manufactured by Mitsubishi Chemical Corporation) 50 parts by mass, urethane acrylic oligomer (product name: EB-600, manufactured by Daicel Cytec) 40 parts by mass, acrylic monomer (product name: A-DCP, manufactured by Shin-Nakamura Chemical Co., Ltd.) ) 5 parts by mass, 2 parts by mass of a silane coupling agent (product name: KBM-503, manufactured by Shin-Etsu Silicone), 5 parts by mass of Perhexa C (manufactured by NOF Corporation) as a thermosetting initiator, and 5 mass of benzophenone as a photocuring initiator Part and conductive particles (product name: AUL704, particle size: 4 μm, manufactured by Sekisui Chemical Co., Ltd.) were mixed to prepare an adhesive composition. Then, an adhesive composition was applied to a separately prepared release-treated PET film having a thickness of 38 μm with a bar coater and dried to obtain an anisotropic conductive film having a thickness of 20 μm.

(Measurement of minimum melt viscosity)
The minimum melt viscosity of the produced anisotropic conductive film was measured. First, a laminated sheet having a thickness of 300 μm was formed by overlaying anisotropic conductive films. Next, the laminated sheet was set on a melt viscometer (manufactured by Thermo Fisher Scientific). And the minimum melt viscosity of the anisotropic conductive film was measured by driving a melt viscometer on the conditions of temperature rising rate 10 degree-C / min, frequency 1Hz, applied pressure 1N, and measurement temperature range 30-180 degreeC. The measurement results are summarized in Table 1.

(Measurement of resin flow)
Next, the amount of resin flow was measured. Here, a method for measuring the resin flow amount will be described with reference to FIGS. The produced anisotropic conductive film was cut into a width of 2.0 mm. Next, as shown in FIG. 4, the cut anisotropic conductive film 50 was sandwiched between non-alkaline glass (thickness 0.7 μm) 150. Next, the anisotropic conductive film 50 was pressed from above the non-alkali glass 150 under a heating and pressing condition of 180 ° C.-4 MPa-6 sec with a 2.0 mm wide heat tool. The pressurizing portion was directly above the anisotropic conductive film 50. And the resin spread amount before and behind pressurization was measured, and the resin flow amount was measured from this result. That is, the width B after pressurization shown in FIG. 6 (the width B here is the maximum width of the anisotropic conductive film 50) is the width A before pressurization shown in FIG. 5 (= 2.0 mm). The resin flow amount was measured by dividing by. The results are summarized in Table 1.

(Measurement of elastic modulus)
The prepared anisotropic conductive film was completely cured in an oven at 200 ° C., and then the completely cured film was cut into a width of 2 mm and a length of 50 mm. Then, the film was set in DMA (manufactured by SII), and the DMA was driven in the pulling mode. And the 30 degreeC elasticity modulus E 'was measured. The results are summarized in Table 1.

(Preparation of connection structure for evaluation)
ITO pattern glass was prepared as a base substrate. In this ITO pattern glass, first terminals made of ITO are formed at a pitch of 50 μm. The height of the first terminal was 200 nm, and the thickness of the glass portion was 0.7 μm.

  Moreover, the flexible substrate made from a polyimide was prepared as a flexible substrate. The thickness of the flexible substrate was 38 μm. In addition, second terminals made of tin-plated copper are formed on the flexible substrate at a pitch of 50 μm. The height of the second terminal was 8 μm. Therefore, the thickness of the anisotropic conductive film is 1.4 times or more of the total height of the first terminal and the second terminal. Further, a second wiring pattern made of the same material as the second terminal is formed from the second terminal, and the second wiring pattern is an insulating protective film (SN9000, Hitachi Chemical Co., Ltd.). It was covered.

  Next, a base substrate was set on a sample stage prepared in advance. And the anisotropic conductive film produced above was temporarily stuck on the 1st terminal, and peeling process PET film was peeled off from the anisotropic conductive film. Next, the flexible substrate was placed on the base substrate so that the second terminal was opposed to the first terminal. Here, the insulating protective film is disposed on the outer side in the surface direction of the base substrate. The distance from the end of the base substrate on the insulating protective film side to the end of the insulating protective film on the base substrate side was 0.3 mm.

Next, a Teflon (registered trademark) film having a thickness of 150 μm was placed on the flexible substrate as a buffer material. Next, a 1.2 mm wide heat tool was pressed against the flexible substrate from above the flexible substrate. The pressurizing position by the heat tool was directly above the first terminal row and the second terminal row. The heating and pressing conditions were 180 ° C.-4 MPa-6 sec. Subsequently, the anisotropic conductive film which flowed from the first terminal and the second terminal to the outside in the surface direction of the base substrate was irradiated with ultraviolet rays from below. The ultraviolet irradiation was performed using an LED type ultraviolet irradiation device (USHIO INC.). The irradiation time was 5 seconds. The irradiation intensity was 100 mW / cm ² and the wavelength was 365 nm. The connection structure was produced through the above steps.

(Evaluation of protruding amount of adhesive layer)
The amount of protrusion of the adhesive layer to the outside in the surface direction of the base substrate was evaluated by observation with an optical microscope. The results are summarized in Table 1. The case where the adhesive layer reached the insulating protective film was evaluated as OK. Moreover, the case where the adhesive bond layer did not reach the insulating protective film was evaluated as NG. Here, as an aspect of NG, since the minimum melt viscosity of the anisotropic conductive adhesive is too high, the adhesive layer does not reach the insulating protective film, and the minimum melt of the anisotropic conductive adhesive Since the viscosity is too low, it is assumed that the adhesive layer does not reach the insulating protective film and wraps around the back side of the base substrate. In this example, the former mode was evaluated as NG1, and the latter mode was evaluated as NG2. An example of NG1 is shown in FIG. 7, and an example of NG2 is shown in FIG. In any example, it can be seen that a gap 22 a is formed between the adhesive layer 40 and the insulating protective film 30. In the gap 22a, the wiring pattern 22 is exposed.

(Conduction resistance measurement)
A reliability evaluation test was conducted in which the connection structure was left in an environment of 85 ° C./85% relative humidity for 500 hours. Subsequently, the conduction resistance of the connection structure was measured before and after the reliability evaluation test. Specifically, the conduction resistance value when a current of 1 mA was passed through the connection structure was measured by a four-terminal method. A digital multimeter (manufactured by Yokogawa Electric Corporation) was used for the measurement. Less than 2Ω was evaluated as A, less than 5Ω was evaluated as B, and 5Ω or more was evaluated as C. The measurement results are shown in Table 1.

(Adhesive strength measurement)
A reliability evaluation test was conducted in which the connection structure was left in an environment of 85 ° C./85% relative humidity for 500 hours. Subsequently, the adhesive strength of the connection structure was measured before and after the reliability evaluation test. The measurement was performed using a tensile tester (manufactured by AND). That is, the base substrate of the connection structure was held on the sample stage, and the flexible substrate was pulled up from above. The measurement speed (tensile speed) was 50 mm / sec. The tensile strength when the flexible substrate (specifically, the second terminal) was completely peeled off from the first terminal was defined as the adhesive strength. 7 N / cm or more was evaluated as A, 5-7 N / cm as B, and less than 5 N / cm as C. When the adhesive strength is low, the adhesive layer may peel off when the flexible substrate is bent. The measurement results are summarized in Table 1.

(Short test)
Ni powder having an average particle diameter of 3 μm (arithmetic mean value of sphere equivalent diameter) was sprinkled on the boundary portion between the base substrate and the flexible substrate of the connection structure to uniformly vibrate the connection structure. Thereafter, a voltage of 15 V was applied between the first terminal and the second terminal, and the insulation resistance was measured. The case of 10 ⁶ Ω or more was evaluated as OK, and the case of less than 10 ⁶ Ω was evaluated as NG. The measurement results are summarized in Table 1.

  For Examples 1 to 3, all the results were satisfactory. In Example 4, the adhesive strength after the reliability evaluation test tended to slightly decrease compared to Examples 1 to 3 by removing the photocuring agent. However, the level was practically acceptable. In Example 5, the minimum melt viscosity is higher than in other Examples 1 to 4. For this reason, the protrusion amount of the adhesive layer became insufficient, and the adhesive layer did not reach the insulating protective film. However, when the insulating protective film was brought closer to the base substrate side and the distance between them was 0.2 mm, the adhesive layer reached the insulating protective film. As a result, an OK result was obtained in the short test. In Example 6, the 30 ° C. elastic modulus was higher than in other Examples 1 to 5. For this reason, the adhesive layer became hard physically and the adhesive strength was lowered. However, there was no problem in practical use. In Comparative Example 1, the minimum melt viscosity exceeds 1000. For this reason, the protrusion amount of the adhesive layer became insufficient, and the adhesive layer did not reach the insulating protective film. In Comparative Example 2, the minimum melt viscosity is less than 100. For this reason, the adhesive layer wraps around the back surface of the base substrate and does not reach the insulating protective film.

  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 Connection structure 10 Base board 11 1st terminal 12 1st wiring pattern 20 Flexible board 21 2nd terminal 22 2nd wiring pattern 30 Insulating protective film 40 Adhesive layer 50 Anisotropic conductive film

Claims (9)

A base substrate;
A first terminal provided on the base substrate;
A flexible substrate;
A wiring pattern provided on the flexible substrate;
An insulating protective film covering the wiring pattern;
A second terminal connected to the wiring pattern;
An anisotropic conductive adhesive layer for anisotropically conductively connecting the first terminal and the second terminal;
The insulating protective film is disposed on the outside in the surface direction of the base substrate,
The anisotropic conductive connection structure, wherein the anisotropic conductive adhesive layer extends from the second terminal to an end of the insulating protective film on the base substrate side.   The anisotropic conductive connection structure according to claim 1, wherein a distance from an end portion of the base substrate on the insulating protective film side to an end portion of the insulating protective film on the base substrate side is 0.3 mm or less. .   The anisotropic conductive connection structure according to claim 1 or 2, wherein the anisotropic conductive adhesive layer has a 30 ° C elastic modulus of 4.0 GPa or less. Preparing a base substrate provided with a first terminal;
Preparing a flexible substrate provided with a wiring pattern, an insulating protective film covering the wiring pattern, and a second terminal connected to the wiring pattern;
Preparing an anisotropic conductive adhesive comprising an uncured polymerizable compound, a thermosetting initiator, and conductive particles;
Sandwiching the anisotropic conductive adhesive between the first terminal and the second terminal, and disposing the insulating protective film on the outside in the surface direction of the base substrate;
By thermocompression bonding the base substrate and the flexible substrate, the first terminal and the second terminal are anisotropically conductively connected, and the anisotropic conductive adhesive is attached to the insulating protective film. An anisotropic conductive connection method comprising: flowing to an end portion on the base substrate side. The anisotropic conductive adhesive further includes a photocuring initiator,
Irradiating light to the anisotropic conductive adhesive that has flowed to the outside in the surface direction of the base substrate after flowing the anisotropic conductive adhesive to the end of the insulating protective film on the base substrate side, The anisotropic conductive connection method according to claim 4. The flexible substrate is disposed above the base substrate,
The anisotropic conductive connection method according to claim 5, wherein the anisotropic conductive adhesive is irradiated with light from below the anisotropic conductive adhesive. The anisotropic conductive adhesive is an anisotropic conductive film,
7. The thickness of the anisotropic conductive film according to claim 4, wherein the thickness of the anisotropic conductive film is at least 1.4 times the total height of the first terminal and the second terminal. Anisotropic conductive connection method. An uncured polymerizable compound, a thermosetting initiator, and conductive particles;
The minimum melt viscosity in an uncured state is 100 to 1000 Pa · s,
An anisotropic conductive adhesive having a 30 ° C. elastic modulus of 4.0 GPa or less after complete curing. The anisotropic conductive adhesive according to claim 8, further comprising a photocuring initiator.

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