JP6639874B2 - Photocurable anisotropic conductive adhesive, method for manufacturing connector, and method for connecting electronic components - Google Patents

Description

  The present invention relates to a photocurable anisotropic conductive adhesive containing a photopolymerizable compound, a photopolymerization initiator, and a light absorber, a method for manufacturing a connector using the same, and a method for connecting electronic components. .

  2. Description of the Related Art In recent years, as liquid crystal screens have become larger and thinner, as represented by large-screen televisions, transparent substrates to which electronic components such as various IC chips and flexible substrates are connected have become thinner and narrower. Therefore, when connecting a transparent substrate and an electronic component using an anisotropic conductive film (ACF) of a thermosetting type, there is a concern that an influence of thermal stress on the transparent substrate and the electronic component due to a high heat-pressing temperature. Is done. Also, when the temperature is lowered to room temperature after the connection using the anisotropic conductive film is performed, the transparent substrate is warped due to the temperature difference between the electronic component in contact with the thermocompression bonding tool and the transparent substrate. In addition, there is a risk of causing problems such as display unevenness occurring on the liquid crystal screen around the connection portion and poor connection of electronic components.

  In addition to these effects, in recent years, in order to meet the demand for shortening the tact time in order to improve productivity, in recent years, by curing the binder resin with ultraviolet light, light that can be connected at a low temperature and in a short time is used. A curable anisotropic conductive adhesive is used.

JP-A-7-1751 JP-A-8-292517

  In the connection method using the photocurable anisotropic conductive adhesive, light in a wavelength region other than the generation region wavelength of cations and radicals generated by light irradiation is not particularly used and is cut by a filter and is not used. .

  Also, in order to soften and flow the photo-curing anisotropic conductive adhesive, a high-temperature thermocompression bonding tool is abutted, so that the thermal expansion and deformation of the binder resin on the electronic component side increases. In addition, the substrate and the electronic component are likely to be warped. In addition, in order to transfer the heat of the thermocompression bonding tool to the binder resin via the electronic components, the binder resin is sufficiently melted and fluidized, and the conductive particles are sufficiently pressed in to ensure conductivity. And pressurizing for a long time, there is a limit to shortening the tact time.

  The present invention is to solve the above-mentioned problem, and by using a photo-curable adhesive, it is possible to connect electronic components at a low temperature and in a short time, to enhance fluidity of a binder resin, and to improve conductivity. It is an object of the present invention to provide a photocurable anisotropic conductive adhesive, a method for manufacturing a connector, and a method for connecting an electronic component.

In order to solve the above-mentioned problems, an anisotropic conductive adhesive according to the present invention is a photocurable anisotropic conductive adhesive that is cured by irradiation with ultraviolet light, and includes a conductive adhesive layer and an insulating adhesive. Having a layer, the conductive adhesive layer contains a film-forming resin, a photopolymerizable compound, a photopolymerization initiator, and conductive particles, and the insulating adhesive layer contains a film-forming resin. A photopolymerizable compound, a photopolymerization initiator, and a light absorber, wherein the light absorption peak wavelength of the light absorber is at least 20 nm larger than the light absorption peak wavelength of the photopolymerization initiator, and The photocurable anisotropic conductive adhesive has a light absorption peak wavelength of the light absorber of 320 nm to 360 nm and a light absorption peak wavelength of the photopolymerization initiator of 290 nm to 330 nm .
In the present invention, the conductive adhesive layer is also effective when the insulating adhesive layer further contains a light absorber in an amount smaller than the light absorber contained in the insulating adhesive layer .
In the present invention, the thickness of the insulating adhesive layer is also effective when the thickness is smaller than the thickness of the conductive adhesive layer.
The present invention is also a method for manufacturing a connector, wherein electronic components are arranged on a transparent substrate placed on a stage via a photocurable anisotropic conductive adhesive that is cured by irradiation with ultraviolet light. And a step of irradiating the photocurable anisotropic conductive adhesive with light with a light irradiator while pressing the electronic component against the transparent substrate with a pressure bonding tool. The system anisotropic conductive adhesive is a film-forming resin, a photopolymerizable compound, a photopolymerization initiator, a conductive adhesive layer containing conductive particles, a film-forming resin, and a photopolymerizable compound. A photopolymerization initiator and an insulating adhesive layer containing a light absorber, wherein the light absorption peak wavelength of the light absorber is at least 20 nm larger than the light absorption peak wavelength of the photopolymerization initiator, and The light absorption peak wavelength of the light absorber is from 320 nm to 360 n. , And the light absorption peak wavelength of the photopolymerization initiator, a method of manufacturing a 290nm~330nm connector.
In the present invention, the conductive adhesive layer is also effective when the insulating adhesive layer further contains a light absorber in an amount smaller than the light absorber contained in the insulating adhesive layer.
In the present invention, the photocurable anisotropic conductive adhesive is also effective when it has a thickness greater than the height of the connection terminal of the electronic component.
Furthermore, the present invention is a method for connecting electronic components, wherein a step of arranging the electronic components via a photo-curing anisotropic conductive adhesive on a transparent substrate mounted on a stage, Performing a light irradiation on the photocurable anisotropic conductive adhesive with a light irradiator while pressing the electronic component against the transparent substrate; The agent is a film-forming resin, a photopolymerizable compound, a photopolymerization initiator, a conductive adhesive layer containing conductive particles, a film-forming resin, a photopolymerizable compound, and a photopolymerization initiator. An insulating adhesive layer containing a light absorbing agent, wherein the light absorbing peak wavelength of the light absorbing agent is at least 20 nm larger than the light absorbing peak wavelength of the photopolymerization initiator, and The light absorption peak wavelength is from 320 nm to 360 nm, Light absorption peak wavelength of agent is a method of connecting an electronic component is 290Nm～330nm.
In the present invention, the conductive adhesive layer is also effective when the insulating adhesive layer further contains a light absorber in an amount smaller than the light absorber contained in the insulating adhesive layer.
In the present invention, the photocurable anisotropic conductive adhesive is also effective when it has a thickness greater than the height of the connection terminal of the electronic component.

  According to the present invention, when the insulating adhesive layer of the photocurable anisotropic conductive adhesive is irradiated with light such as ultraviolet light, the light absorber generates heat, and the binder resin softens and flows. It will be easier. This allows the connection terminals of the electronic component to be pushed into the insulating adhesive layer while melting the binder resin of the insulating adhesive layer. In addition, by irradiating the conductive adhesive layer with light such as ultraviolet light, the connection terminals of the electronic component can be pushed into the conductive adhesive layer while the binder resin is being cured. At this time, since the conductive adhesive layer has low fluidity of the binder resin and the conductive particles are hard to move, the conductive particles do not flow out of the connection portion at the top of the connection terminal of the electronic component, and many conductive particles Can be captured. That is, according to the present invention, the electronic components can be connected in a short time at a low temperature, the fluidity of the binder resin can be increased, and the conductivity can be improved.

FIG. 1 is a cross-sectional view of a liquid crystal display panel shown as an example of a connector according to the present invention. FIG. 3 is a cross-sectional view illustrating a liquid crystal driving IC, a transparent substrate, and an anisotropic conductive film. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the anisotropic conductive film as an example of this invention. (A) (b): It is sectional drawing which shows an example of the connection method of the connection body which concerns on this invention. 4 is a graph showing a relationship between a photopolymerization initiator of a photocurable anisotropic conductive adhesive according to the present invention and a light absorption peak wavelength of a light absorber. It is a perspective view which shows the process of measuring the connection resistance of the connection body sample which concerns on an Example and a comparative example.

  Hereinafter, a photocurable anisotropic conductive adhesive to which the present invention is applied, a method of manufacturing a connector, and a method of connecting an electronic component will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to only the following embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention. Further, the drawings are schematic, and the ratios of the respective dimensions may be different from actual ones. Specific dimensions and the like should be determined in consideration of the following description. In addition, it is needless to say that dimensional relationships and ratios are different between drawings.

  Hereinafter, a so-called COG (chip on glass) system in which an IC chip for driving a liquid crystal is mounted as an electronic component on a glass substrate of a liquid crystal display panel will be described as an example. In this liquid crystal display panel 10, for example, as shown in FIG. 1, two flat transparent substrates 11, 12 made of a glass substrate or the like are arranged to face each other. It is stuck. The liquid crystal display panel 10 has a panel display section 15 formed by enclosing a liquid crystal material 14 in a space surrounded by the transparent substrates 11 and 12 and the seal 13.

  The transparent substrates 11 and 12 have a pair of striped transparent electrodes 16 and 17 made of ITO (indium tin oxide) or the like formed on both inner surfaces facing each other so as to cross each other. The transparent electrodes 16 and 17 are configured such that a pixel as a minimum unit of a liquid crystal display is formed by the intersection of the transparent electrodes 16 and 17.

One of the transparent substrates 11 and 12 is formed to have a larger planar dimension than the other transparent substrate 11, and the large formed portion is made to protrude laterally from the panel display unit 15. Thus, an edge 12a is provided.
On the surface of the edge 12a of the transparent substrate 12 on the side of the transparent substrate 11, a COG mounting section 20 on which a liquid crystal driving IC 18 (electronic component) is mounted is provided near the panel display section 15. In the vicinity of the front end side of the edge portion 12a of the transparent substrate 12, an FOG mounting portion 22 on which a flexible substrate 21 (electronic component) on which a liquid crystal drive circuit is formed is mounted.
On the COG mounting portion 20 and the FOG mounting portion 22, for example, a plurality of terminal portions 17a of the transparent electrode 17 are formed (see FIG. 2).
Note that the COG mounting portion 20 has the terminal portion 17a of the transparent electrode 17 and the substrate-side alignment mark 23 formed thereon (see FIG. 2).

  The liquid crystal driving IC 18 can perform a predetermined liquid crystal display by selectively applying a liquid crystal driving voltage to the pixels to partially change the orientation of the liquid crystal. As shown in FIG. 2, a mounting surface 18a provided on one surface of the liquid crystal driving IC 18 is electrically connected to a terminal portion 17a of the transparent electrode 17 via an anisotropic conductive film 1 described later. A plurality of electrode terminals 19 are formed. As the electrode terminal 19, for example, a copper bump, a gold bump, or a copper bump plated with gold is preferably used.

  Further, on the mounting surface 18a of the liquid crystal driving IC 18, an IC alignment mark 24 for performing alignment with the transparent substrate 12 is formed by overlapping with the substrate alignment mark 23 described above. Since the wiring pitch of the transparent electrodes 17 on the transparent substrate 12 and the fine pitch of the electrode terminals 19 of the liquid crystal driving IC 18 have been advanced, high-precision alignment adjustment between the liquid crystal driving IC 18 and the transparent substrate 12 is required. Have been.

As shown in FIG. 1, the photocurable anisotropic conductive adhesive according to the present invention is provided on the mounting portions 20 and 22 of the edge 12 a of the transparent substrate 12 and on the terminal portions 17 a of the transparent electrode 17. The liquid crystal driving IC 18 and the flexible substrate 21 are connected using a certain anisotropic conductive film 1.
The anisotropic conductive film 1 contains conductive particles 4 as described later, and is connected to the electrodes of the liquid crystal driving IC 18 and the flexible substrate 21 and the terminals of the transparent electrode 17 formed on the edge 12 a of the transparent substrate 12. The portion 17 a is electrically connected to the portion 17 a via the conductive particles 4.
The anisotropic conductive film 1 is an ultraviolet-curable film-like adhesive, and is irradiated with ultraviolet light by an ultraviolet irradiator 35 to be described later and is pressed by a thermocompression bonding tool 33 to be a fluidized binder. In the resin, the conductive particles 4 are crushed between the terminal portion 17a and each electrode of the liquid crystal driving IC 18 and the flexible substrate 21, and the conductive particles 4 are cured in a crushed state. Thus, the anisotropic conductive film 1 electrically and mechanically connects the transparent substrate 12 with the liquid crystal driving IC 18 and the flexible substrate 21.

  An alignment film 27 that has been subjected to a predetermined rubbing process is formed on each of the above-mentioned transparent electrodes 16 and 17, and the initial alignment of the liquid crystal molecules of the liquid crystal material 14 is regulated by these alignment films 27. It has become so. Further, a pair of polarizers 25 and 26 are provided outside the transparent substrates 11 and 12, and the transmitted light from a light source (not shown) such as a backlight is provided by the polarizers 25 and 26. The direction of vibration is regulated.

[Photocurable anisotropic conductive film]
In the present invention, a photocurable anisotropic conductive film (ACF) 1 is used. The anisotropic conductive film 1 may be of a photocationic type or a photoradical type, and can be appropriately selected depending on the purpose.

  The anisotropic conductive film 1 includes a conductive adhesive layer 5 and an insulating adhesive layer 6, for example, as shown in FIG. The anisotropic conductive film 1 has a conductive adhesive layer 5 supported on a release film 2 serving as a base material, and an insulating adhesive layer 6 laminated on the conductive adhesive layer 5.

  As the release film 2, a base material such as a polyethylene terephthalate film generally used in known anisotropic conductive films can be used.

  As shown in FIG. 2, for example, the anisotropic conductive film 1 is interposed between a terminal portion 17a of a transparent electrode 17 formed on a transparent substrate 12 of a liquid crystal display panel 10 and an electrode terminal 19 of a liquid crystal driving IC 18. Is done. At this time, in the anisotropic conductive film 1, the insulating adhesive layer 6 is disposed on the transparent substrate 12 side, and the conductive adhesive layer 5 is disposed on the liquid crystal driving IC 18 side.

  Then, as described later, the anisotropic conductive film 1 is pressed from the liquid crystal driving IC 18 side by the thermocompression bonding tool 33 shown in FIG. 1 and is irradiated with ultraviolet light from the transparent substrate 12 side by the ultraviolet irradiator 35. You. At this time, it is pressed at room temperature by the thermocompression bonding tool 33 or at such a low temperature that the binder resin of the conductive adhesive layer 5 and the insulating adhesive layer 6 (hereinafter referred to as “resin” as appropriate) shows fluidity. The configuration is such that the thermal shock applied to the liquid crystal driving IC 18 and the transparent substrate 12 is reduced by being heated and pressed. As a result, the binder resin of the conductive adhesive layer 5 and the insulating adhesive layer 6 is melted, and the conductive particles 4 are sandwiched between the terminal 17a of the transparent electrode 17 and the electrode terminal 19 of the liquid crystal driving IC 18. The transparent electrode 17 of the liquid crystal display panel 10 and the liquid crystal driving IC 18 are electrically and mechanically connected.

  The anisotropic conductive film 1 according to the present invention contains a film-forming resin, a photopolymerization initiator, a photopolymerizable compound, and a light absorber in the insulating adhesive layer 6. Since the insulating adhesive layer 6 contains a light absorbing agent, ultraviolet light is irradiated from the transparent substrate 12 side in addition to the heating and pressing by the thermocompression bonding tool 33 in the later-described connection step of the liquid crystal driving IC 18. Then, the light absorbing agent generates heat, and is likely to soften and flow. Thus, the electrode terminals 19 of the liquid crystal driving IC 18 can be pressed into the insulating adhesive layer 6 by the thickness thereof while the binder resin of the insulating adhesive layer 6 is melted.

  The heat generation temperature of the light absorbing agent is such that the binder resin is softened enough to push the conductive particles 4 into the insulating adhesive layer 6, and the heat shock is applied to the transparent substrate 12 and the liquid crystal driving IC 18. The temperature is preferably a predetermined temperature, for example, about 80 to 90 [deg.] C., and can be appropriately set by selecting the material of the light absorber.

  When the conductive adhesive layer 5 is heated and pressed by the thermocompression bonding tool 33 and is irradiated with ultraviolet light, the electrode terminals 19 of the liquid crystal driving IC 18 are cured while the binder resin is cured. You can push it in. At this time, since the conductive adhesive layer 5 has low fluidity of the binder resin and the conductive particles 4 are hard to move, the conductive adhesive layer 5 has a conductive property between the electrode terminal 19 of the liquid crystal driving IC 18 and the terminal portion 17 a of the transparent substrate 12. The particles 4 do not flow out, and many conductive particles 4 can be captured.

[Photocationic anisotropic conductive film]
The photocationic anisotropic conductive film 1 contains a film-forming resin, a photocationic polymerization initiator, and a photocationic polymerizable compound in the conductive adhesive layer 5, and forms a film in the insulating adhesive layer 6. It contains a resin, a cationic photopolymerization initiator, a cationic photopolymerizable compound, and a light absorber.

  As the film-forming resin, a resin having an average molecular weight of about 10,000 to 80,000 is preferable. Examples of such a film-forming resin include various resins such as a phenoxy resin, an epoxy resin, a modified epoxy resin, and a urethane resin. Among them, a phenoxy resin is particularly preferable from the viewpoint of ensuring a uniform film formation state and high connection reliability.

  Examples of the cationic photopolymerization initiator include onium salts such as iodonium salts, sulfonium salts, aromatic diazonium salts, phosphonium salts and selenonium salts, complex compounds such as metal arene complexes and silanol / aluminum complexes, benzoin tosylate, o -Nitrobenzyl tosylate and the like can be used. In addition, as a counter anion when forming a salt, propylene carbonate, hexafluoroantimonate, hexafluorophosphate, tetrafluoroborate, tetrakis (pentafluorophenyl) borate and the like are used.

  As the cationic photopolymerization initiator, only one kind may be used alone, or two or more kinds may be used in combination. Among them, an aromatic sulfonium salt can be suitably used because it has an ultraviolet absorbing property even in a wavelength region of 300 nm or more and has excellent curability.

  The photocationically polymerizable compound is a compound having a functional group that is polymerized by a cationic species, and examples of such a compound include an epoxy compound, a vinyl ether compound, and a cyclic ether compound.

  The epoxy compound is a compound having two or more epoxy groups in one molecule. Examples of such a compound include a bisphenol-type epoxy resin derived from epichlorohydrin and bisphenol A or bisphenol F, or a polyglycidyl ether. Glycidyl ester, aromatic epoxy compound, alicyclic epoxy compound, novolak type epoxy compound, glycidylamine type epoxy compound, glycidyl ester type epoxy compound and the like.

  The light absorber generates heat when irradiated with ultraviolet light in the connection step of the liquid crystal driving IC 18 to melt the binder resin of the insulating adhesive layer 6. When the photoabsorber uses a photocationic polymerization initiator as a photopolymerization initiator, for example, a benzotriazole-based, triazine-based, benzophenone-based ultraviolet absorber can be suitably used, and a photocationic polymerization initiator can be used. Is appropriately selected according to the absorption peak wavelength, the spectral distribution of the ultraviolet irradiator 35, the compatibility with other components of the binder resin, the ultraviolet absorbing ability, and the like. When a cationic polymerization initiator is used as the photopolymerization initiator, a photoradical polymerization initiator may be used as a light absorber that generates heat by absorbing ultraviolet light.

[Photo-radical anisotropic conductive film]
The photo-radical anisotropic conductive film 1 contains a film-forming resin, a photo-radical polymerization initiator, and a photo-radical polymerizable compound in the conductive adhesive layer 5, and forms a film in the insulating adhesive layer 6. It contains a resin, a photoradical polymerization initiator, a photoradical polymerizable compound, and a light absorber.

  As the film-forming resin, the same resin as the above-described photocationic anisotropic conductive film can be used.

  Examples of the photoradical polymerization initiator include benzoin ethers such as benzoin ethyl ether and isopropyl benzoin ether, benzyl ketals such as benzyl and hydroxycyclohexyl phenyl ketone, ketones such as benzophenone and acetophenone and derivatives thereof, thioxanthones, and bisimidazoles. No. If necessary, sensitizers such as amines, sulfur compounds, and phosphorus compounds may be added to these photopolymerization initiators in any ratio. At this time, it is necessary to select an optimal photoinitiator according to the wavelength of the light source used, the desired curing characteristics, and the like.

  In addition, an organic peroxide-based curing agent can be used as a compound that generates active radicals by light irradiation. As the organic peroxide, one or more of diacyl peroxide, dialkyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, hydroperoxide, silyl peroxide and the like can be used.

  The photo-radical polymerizable compound is a substance having a functional group that is polymerized by an active radical, and examples of such a compound include an acrylate compound, a methacrylate compound, and a maleimide compound.

  The photo-radical polymerizable compound can be used in any state of a monomer and an oligomer, and a monomer and an oligomer can be used in combination.

  Examples of the acrylate compound and the methacrylate compound include photopolymerizable oligomers such as epoxy acrylate oligomer, urethane acrylate oligomer, polyether acrylate oligomer, and polyester acrylate oligomer; trimethylolpropane triacrylate, polyethylene glycol diacrylate, and polyalkylene glycol. Diacrylate, pentaerythritol acrylate, 2-cyanoethyl acrylate, cyclohexyl acrylate, dicyclopentenyl acrylate, dicycloventenyloxyethyl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate, 2-ethoxyethyl acrylate, 2-ethylhexyl Acrylate, n-hexyl acrylate, 2-hydroxyethyl Rate, hydroxypropyl acrylate, isobornyl acrylate, isodecyl acrylate, isooctyl acrylate, n-lauryl acrylate, 2-methoxyethyl acrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, neopentyl glycol diacrylate, Examples thereof include photopolymerizable monofunctional and polyfunctional acrylate monomers such as dipentaerythritol hexaacrylate. These may be used alone or in combination of two or more.

  As the light absorber, for example, a benzotriazole-based, triazine-based, benzophenone-based ultraviolet absorber can be suitably used, and the absorption peak wavelength of the photoradical polymerization initiator, the spectral distribution of the ultraviolet irradiator 35, the insulating property It is appropriately selected according to the compatibility with other components of the adhesive layer 6 and the ultraviolet absorbing ability.

  In addition, the conductive adhesive layer 5 and the insulating adhesive layer 6 may contain an additive such as a silane coupling agent or an inorganic filler. Examples of the silane coupling agent include an epoxy type, an amino type, a mercapto sulfide type, and a ureide type. By adding the silane coupling agent, the adhesiveness at the interface between the organic material and the inorganic material is improved.

  As the conductive particles 4, any known conductive particles used in a general anisotropic conductive film can be used. Examples of the conductive particles 4 include particles of various metals and metal alloys such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, and gold, metal oxides, carbon, graphite, glass, ceramics, and the like. Examples thereof include particles obtained by coating the surface of particles of plastic or the like with a metal, or particles obtained by further coating the surface of these particles with an insulating thin film. When the surface of the resin particles is coated with a metal, examples of the resin particles include an epoxy resin, a phenol resin, an acrylic resin, an acrylonitrile / styrene (AS) resin, a benzoguanamine resin, a divinylbenzene resin, and a styrene resin. Can be mentioned.

  In the anisotropic conductive film 1 described above, the conductive adhesive layer 5 does not contain a light absorber, but the conductive adhesive layer 5 also contains a light absorber and is softened by irradiation with ultraviolet light. May be promoted. However, the amount of the light absorbing agent contained in the conductive adhesive layer 5 (ratio to the mass of the binder resin) is based on the amount of the light absorbing agent contained in the insulating adhesive layer 6 (the ratio to the mass of the binder resin). It is preferable that the fluidity of the insulating adhesive layer 6 is relatively increased.

  Further, in the anisotropic conductive film 1, it is preferable that the light absorption peak wavelength of the light absorber is different from the light absorption peak wavelength of the photopolymerization initiator. Since the light absorption peak wavelengths of the light absorber and the photopolymerization initiator are different, when ultraviolet light is irradiated by the ultraviolet irradiator 35, both the light absorber and the photopolymerization initiator efficiently react with the ultraviolet light. The exothermic reaction and the curing reaction can proceed simultaneously.

[Light absorption peak wavelength of photopolymerization initiator and light absorber]
In the photocurable anisotropic conductive film 1 according to the present invention, the light absorption peak wavelength of the light absorber is preferably larger than the light absorption peak wavelength of the photopolymerization initiator, and is preferably separated by 20 nm or more. When the anisotropic conductive film 1 is irradiated with ultraviolet light from the ultraviolet irradiator 35, the photopolymerization initiator absorbs the ultraviolet light and generates an acid or a radical. The light absorber also absorbs ultraviolet light and generates heat.

  Here, if the light absorption peak of the photopolymerization initiator and the light absorption peak of the light absorber are close to each other, the absorption of ultraviolet light is mutually inhibited, and the curing reaction and heat generation become insufficient. As a result, the binder resin is not melted, and the curing of the binder resin proceeds in a state where the conductive particles 4 are insufficiently pushed, and the conduction resistance may increase due to a change with time or an environmental change after connection.

  In addition, the light absorption peak wavelengths of the light absorber and the photopolymerization initiator generally have a predetermined width, as shown in FIG. 5, whereas the light absorption peak wavelength of the light absorber exhibits a plurality of maximum values. Since the light absorption peak wavelength of the photopolymerization initiator has a profile exhibiting one maximum value, when the light absorption peak wavelength of the light absorption agent is smaller than the light absorption peak wavelength of the photopolymerization initiator, the distance is 20 nm or more. However, the overlapping range of absorption wavelengths other than the peak becomes large, absorption of ultraviolet light is mutually inhibited, and curing reaction and heat generation become insufficient.

  On the other hand, by using, as the light absorber and the photopolymerization initiator, those having a light absorption peak wavelength of the light absorber that is 20 nm or more larger than the light absorption peak wavelength of the photopolymerization initiator, The progress of the curing reaction of the binder resin and the melting of the binder resin due to heat generation can be performed without inhibiting absorption of each ultraviolet light.

  The light absorption peak wavelength of the photopolymerization initiator used in the present invention is specifically from 290 nm to 330 nm, and the light absorption peak wavelength of the light absorber is preferably from 320 nm to 360 nm.

  For example, by using a cationic photopolymerization initiator having a light absorption peak wavelength of ultraviolet light of 310 nm and an ultraviolet light absorber having a light absorption peak wavelength of ultraviolet light of 340 to 360 nm, the cationic photopolymerization initiator and the ultraviolet light absorber can be used. Can promote the curing reaction and heat generation without mutually inhibiting the absorption of ultraviolet light.

[Thickness of anisotropic conductive film]
The anisotropic conductive film 1 according to the present invention preferably has a thickness greater than the height of connection terminals of electronic components such as the electrode terminals 19 of the liquid crystal driving IC 18. When the anisotropic conductive film 1 is pressed by the thermocompression bonding tool 33 and is irradiated with ultraviolet light, the molten resin flows, so that the thickness of the anisotropic conductive film 1 is greater than the height of the electrode terminals 19 of the liquid crystal driving IC 18. With this arrangement, a sufficient amount of resin corresponding to the height of the electrode terminals 19 can be filled between the liquid crystal driving IC 18 and the transparent substrate 12. Thereby, the liquid crystal display panel 10 can ensure the connection reliability between the liquid crystal driving IC 18 and the transparent substrate 12.

  The anisotropic conductive film 1 having a two-layer structure as described above can be formed as follows. First, the adhesive resin composition forming the conductive adhesive layer 5 is applied on the release film 2 and dried, and the adhesive composition forming the insulating adhesive layer 6 is applied on another release film and dried. Let it. Next, by bonding the conductive adhesive layer 5 supported on the release film 2 and the insulating adhesive layer 6 supported on another release film, the anisotropic conductive film 1 having a two-layer structure is formed. Can be formed.

  The shape of the anisotropic conductive film 1 is not particularly limited. For example, as shown in FIG. 3, the anisotropic conductive film 1 is formed into a long tape shape with a release film 2 that can be wound around a take-up reel 8. The adhesive tape 1A can be cut and used for a predetermined length.

[Connection device]
Next, a connection device 30 used in a process of manufacturing a connection body in which the liquid crystal driving IC 18 is connected to the transparent substrate 12 via the above-described anisotropic conductive film 1 will be described.

  As shown in FIG. 1, the connection device 30 includes a stage 31, a thermocompression tool (compression tool) 33, and an ultraviolet irradiator 35.

  The stage 31 is formed of a material having a light transmitting property, such as quartz. The stage 31 is arranged such that the edge 12a of the transparent substrate 12 is placed on the surface thereof, a thermocompression bonding tool 33 is arranged above the surface, and ultraviolet rays are arranged below the back surface. An irradiator 35 is provided.

  The thermocompression bonding tool 33 presses the liquid crystal driving IC 18 mounted on the edge 12 a of the transparent substrate 12 via the anisotropic conductive film 1, and is held by a head moving mechanism (not shown). It is allowed to approach and separate from 31.

  The ultraviolet irradiator 35 irradiates the anisotropic conductive film 1 provided on the terminal portion 17a of the transparent electrode 17 with ultraviolet light from the back side of the stage 31 to generate heat in the light absorber and to increase the transparency. The anisotropic conductive film 1 is cured while the conductive particles 4 are held between the terminal 17a of the electrode 17 and the electrode terminal 19 of the liquid crystal driving IC 18, and the liquid crystal driving IC 18 is connected to the terminal 17a of the transparent electrode 17. Are electrically connected to each other.

  As the ultraviolet irradiator 35, an ultraviolet lamp having a maximum emission wavelength in the absorption peak wavelength region of the photopolymerization initiator can be used. The ultraviolet irradiator 35 is a mercury lamp having a spectral distribution having peaks in the absorption peak wavelength range of the photopolymerization initiator and the absorption peak wavelength range of the light absorber, and both absorption peaks of the photopolymerization initiator and the light absorber. A metal halide lamp or the like that emits ultraviolet light over a wavelength range including the wavelength can be used. The UV irradiator 35 may use both an LED lamp having a peak in the absorption peak wavelength region of the photopolymerization initiator and an LED lamp having a peak in the absorption peak wavelength region of the light absorber.

[Connection process]
Next, a connection process of the liquid crystal driving IC 18 using the connection device 30 described above will be described.
First, the transparent substrate 12 is placed on a stage for temporary bonding (not shown), and the anisotropic conductive film 1 is temporarily pressure-bonded onto the terminal portion 17 a of the transparent electrode 17. The method of temporarily pressing the anisotropic conductive film 1 is such that the anisotropic conductive film 1 is placed on the terminal 17 a of the transparent electrode 17 of the transparent substrate 12 such that the insulating adhesive layer 6 is on the transparent electrode 17 side. Deploy.

  After arranging the anisotropic conductive film 1 on the terminal portion 17a of the transparent electrode 17, the anisotropic conductive film 1 is heated and heated by a temporary pressure bonding head (not shown) from the release film 2 side. By pressing and peeling the release film 2 from the conductive adhesive layer 5, only the conductive adhesive layer 5 and the insulating adhesive layer 6 are temporarily attached on the terminal portion 17 a of the transparent electrode 17. In the temporary compression bonding by the thermal bonding head for temporary bonding, the upper surface of the release film 2 is heated (for example, about 70 to 100 ° C.) while being pressed against the transparent electrode 17 side with a slight pressure (for example, about 0.1 MPa to 2 MPa).

  Next, as shown in FIG. 1, the edge 12a of the transparent substrate 12 is placed on the stage 31, and as shown in FIG. The liquid crystal driving IC 18 is arranged so that the electrode terminals 19 of the driving IC 18 face each other via the conductive adhesive layer 5 and the insulating adhesive layer 6.

Next, as shown in FIG. 1 and FIG. 4B, predetermined ultraviolet light UV is irradiated from the back surface side of the stage 31 by the ultraviolet irradiation device 35, and the upper surface of the liquid crystal driving IC 18 is pressed by the thermocompression tool 33. Press with a predetermined pressure.
At this time, the thermocompression bonding tool 33 is at room temperature (without heating) or at a low temperature (for example, 70 ° C. to 100 ° C.) at which the conductive adhesive layer 5 and the insulating adhesive layer 6 of the anisotropic conductive film 1 show fluidity. About).
The ultraviolet light UV irradiated by the ultraviolet irradiator 35 passes through the stage 31 and the transparent substrate 12 and enters the conductive adhesive layer 5 and the insulating adhesive layer 6 of the anisotropic conductive film 1 to start photopolymerization. Is absorbed by the agent and the light absorber.
Here, the photopolymerization initiator generates an acid or a radical by absorbing ultraviolet light UV, whereby the curing reaction of the conductive adhesive layer 5 and the insulating adhesive layer 6 proceeds. The light absorber generates heat at a predetermined temperature (for example, 80 to 90 ° C.) by absorbing ultraviolet light UV, and melts the insulating adhesive layer 6.

  That is, in this connection step, the binder resin of the insulating adhesive layer 6 of the anisotropic conductive film 1 is melted by the heat generated by the light absorber, and in this state, the anisotropic conductive film 1 is pressed by the thermocompression bonding tool 33. Thereby, the molten resin of the insulating adhesive layer 6 can flow out from between the terminal portion 17a of the transparent electrode 17 and the electrode terminal 19 of the liquid crystal driving IC 18, whereby the electrode terminal 19 and the transparent electrode 17 can be discharged. The conductive particles 4 can be sufficiently pushed into the terminal portion 17a side between the terminal portion 17a and the terminal portion 17a.

  In this connection step, the electrode terminal 19 of the liquid crystal driving IC 18 is connected to the terminal of the transparent electrode 17 while the curing reaction of the conductive adhesive layer 5 of the anisotropic conductive film 1 is advanced by the reaction of the photopolymerization initiator. Push toward 17a. At this time, since the fluidity of the binder resin of the conductive adhesive layer 5 is low, the conductive particles 4 do not flow out of, for example, a lower portion (top), which is a connection portion of the electrode terminal 19 of the liquid crystal driving IC 18, and the electrode terminal Many conductive particles 4 can be captured between 19 and the terminal portion 17 a of the transparent electrode 17.

  The binder of the conductive adhesive layer 5 and the insulating adhesive layer 6 is held in a state where the conductive particles 4 are sandwiched and held between the terminal portion 17 a of the transparent electrode 17 and the electrode terminal 19 of the liquid crystal driving IC 18. The resin is cured. Therefore, in this connection step, the liquid crystal driving IC 18 is pressed at room temperature or at a low temperature at which the binder resin of the conductive adhesive layer 5 and the insulating adhesive layer 6 exhibits fluidity, thereby causing the influence of warpage and liquid crystal driving. It is possible to manufacture a connector having good electrical conductivity and mechanical connectivity with the liquid crystal drive IC 18 while suppressing the influence of thermal shock on electronic components such as the IC 18 for use.

  At this time, as described above, the anisotropic conductive film 1 has, as a photopolymerization initiator and a light absorber, a light absorption peak wavelength of the light absorption agent that is 20 nm or more larger than the light absorption peak wavelength of the photopolymerization initiator. It is preferable to use, thereby, the progress of the curing reaction of the binder resin and the melting of the binder resin due to heat generation, respectively, without obstructing the absorption of each ultraviolet light of the photopolymerization initiator and the light absorber. it can.

  Further, since the heat generated by the light absorber is transmitted equally to the transparent substrate 12 and the liquid crystal driving IC 18, a heat gradient is generated between the transparent substrate 12 and the liquid crystal driving IC 18, unlike the case where the heat absorption is performed by the thermocompression bonding tool 33. Without such occurrence, problems such as generation of warpage due to a difference in heating temperature, display unevenness due to the warpage, and poor connection of electronic components are greatly improved.

  The irradiation time, the illuminance, and the total irradiation amount by the ultraviolet irradiator 35 are determined in consideration of the composition of the binder resin, the pressure and the time by the thermocompression bonding tool 33, and the progress of the curing reaction of the binder resin and the pressing by the thermocompression tool 33. Conditions for improving the connection reliability and the adhesive strength by the method are set as appropriate.

  Thereafter, the thermocompression bonding tool 33 of the connection device 30 is moved above the stage 31 to complete the main pressure bonding step of the liquid crystal driving IC 18.

  After connecting the liquid crystal driving IC 18 to the terminal portion 17a of the transparent electrode 17 of the transparent substrate 12, the flexible substrate 21 is mounted on the transparent electrode 17 of the transparent substrate 12 by the same process as the connection process of the liquid crystal driving IC 18. A so-called FOG (film on glass) connection process is performed. Also at this time, similarly to the above, by using the anisotropic conductive film 1 according to the present invention, the ultraviolet light UV from the ultraviolet irradiator 35 is absorbed, and the heat generated by the light absorber melts the binder resin and causes the acid or The curing reaction due to the generation of radicals can proceed.

  Thereby, it is possible to manufacture a connection body in which the transparent substrate 12 is connected to the liquid crystal driving IC 18 and the flexible substrate 21 via the anisotropic conductive film 1. Note that the connection steps by the COG method and the FOG method may be performed simultaneously.

  The COG method in which the liquid crystal driving IC is directly mounted on the glass substrate of the liquid crystal display panel and the FOG method in which the flexible substrate is directly mounted on the liquid crystal display panel substrate have been described above as examples. If it is a manufacturing process of a connector using a mold adhesive, it can be applied to various connections other than mounting electronic components on a transparent substrate.

[Others]
Further, in the present invention, in addition to using the above-described ultraviolet-curable conductive adhesive, a light-curable conductive adhesive that is cured by a light beam having another wavelength such as infrared light can also be used.

  In this connection step, a heating mechanism such as a heater may be provided on the stage 31 to heat the transparent substrate 12 at a temperature lower than the heat generation temperature of the light absorber. Thereby, the binder resin of the conductive adhesive layer 5 and the insulating adhesive layer 6 is melted in combination with the heat generation of the light absorber, and the terminal portion 17a of the transparent electrode 17 and the electrode terminal 19 of the liquid crystal driving IC 18 are surely connected. By holding the conductive particles 4 therebetween, the connectivity of the connection body can be improved.

  Next, examples of the present invention will be described. In this example, the average number of trapped conductive particles (pcs) and the conductive resistance value of a sample of a connection body between a transparent substrate and an IC chip manufactured by changing the layer structure of the anisotropic conductive film and the compounding conditions of each layer were different. The connection state between the IC chip and the transparent substrate was evaluated by (Ω).

  As an adhesive used for connection, an anisotropic conductive film formed into a film having a width of 4.0 mm and a length of 40.0 mm, comprising a binder resin layer containing a cationic photopolymerization initiator and a cationically polymerizable compound, was prepared. .

  As an evaluation element for checking the number of captured conductive particles, an evaluation IC (A) having a thickness of 0.5 mm and having an IC bump having a height of 15 μm was prepared. In addition, as an evaluation element for measuring the conduction resistance, an evaluation IC (B) having an outer shape of 1.8 mm × 34 mm, a thickness of 0.5 mm, and a wiring for measurement of conduction and an IC bump having a height of 10 μm was prepared.

  As the evaluation substrate (A) to which the evaluation IC (A) is connected, a 0.5 mm-thick elementary glass was prepared. In addition, as the evaluation base material (b) to which the evaluation IC (B) was connected, a measurement ITO coating lath having a thickness of 0.5 mm on which continuity measurement wiring was formed was used.

The evaluation ICs (A) and (B) are arranged on the evaluation base materials (A) and (B) via an anisotropic conductive film, and are pressurized by a thermocompression bonding tool (10.0 mm × 40.0 mm) and irradiated with ultraviolet rays. By connecting by irradiation, a sample of the connected body was formed. The thermocompression bonding tool has a pressing surface subjected to a fluorine resin processing with a thickness of 0.05 mm. The pressing conditions of the thermocompression bonding tool are 70 MPa and 5 seconds at room temperature. Irradiation of ultraviolet light by an ultraviolet irradiator (SP-9: manufactured by Ushio Inc.) is started simultaneously with the pressing of the thermocompression bonding tool, and the irradiation time is 5 seconds. The illuminance of the ultraviolet irradiator was 300 mW / cm ^{2 at} 365 nm, and the size of the ultraviolet light irradiation area was about 4.0 mm in width × about 44.0 mm in length.

[Example 1]
In Example 1, an anisotropic conductive film having a 20 μm thick binder resin layer in which a 10 μm thick conductive adhesive layer (ACF layer) and a 10 μm thick insulating adhesive layer (NCF layer) were laminated was used. Was.
The conductive adhesive layer according to Example 1 was formed by preparing a resin solution in which the following components were mixed, applying the resin solution on a PET film, and drying.

Phenoxy resin (YP-70: Nippon Steel & Sumitomo Chemical Co., Ltd.); 20 parts by mass liquid epoxy resin (EP828: Mitsubishi Chemical Co., Ltd.); 30 parts by mass solid epoxy resin (YD014: Nippon Steel & Sumitomo Chemical Co., Ltd.); 20 mass Part conductive particles (AUL704: manufactured by Sekisui Chemical Co., Ltd.); 30 parts by mass photocationic polymerization initiator (SP-170: manufactured by ADEKA Corporation); 5 parts by mass

  The insulating adhesive layer in Example 1 was formed by preparing a resin solution in which the following components were mixed, coating the resin solution on a PET film, and drying.

Phenoxy resin (YP-70: Nippon Steel & Sumitomo Chemical Co., Ltd.); 20 parts by mass liquid epoxy resin (EP828: Mitsubishi Chemical Co., Ltd.); 30 parts by mass solid epoxy resin (YD014: Nippon Steel & Sumitomo Chemical Co., Ltd.); 20 mass Part photo cationic polymerization initiator (SP-170: manufactured by ADEKA Corporation); 5 parts by mass Light absorber (LA-31: manufactured by ADEKA Corporation); 5 parts by mass

  Then, by laminating the conductive adhesive layer and the insulating adhesive layer, an anisotropic conductive film according to Example 1 formed into a film having a width of 4.0 mm and a length of 40.0 mm was obtained. .

  The absorption peak wavelength of the photocationic polymerization initiator (SP-170) in Example 1 is about 310 nm, and the absorption peak wavelength of the light absorber (LA-31) is about 340 nm, and the difference is 30 nm.

[Example 2]
In Example 2, an anisotropic conductive film including a 15 μm thick binder resin layer in which a 10 μm thick conductive adhesive layer and a 5 μm thick insulating adhesive layer were laminated was used. The composition of the conductive adhesive layer and the insulating adhesive layer in the second embodiment is the same as in the first embodiment.

[Example 3]
In Example 3, an anisotropic conductive film provided with a 15 μm thick binder resin layer in which a 10 μm thick conductive adhesive layer and a 5 μm thick insulating adhesive layer were laminated was used. In Example 3, 1 part by mass of a light absorber (LA-31: manufactured by ADEKA Corporation) was mixed into the conductive adhesive layer. Otherwise, the conductive adhesive layer and the insulating adhesive layer had the same layer thickness and the same composition as in Example 2.

[Comparative Example 1]
In Comparative Example 1, an anisotropic conductive film provided with a 20 μm thick binder resin layer composed of a 20 μm thick conductive adhesive layer was used. The composition of the conductive adhesive layer is the same as that of the conductive adhesive layer of Example 1.

[Comparative Example 2]
In Comparative Example 2, an anisotropic conductive film provided with a 20 μm thick binder resin layer composed of a 20 μm thick conductive adhesive layer was used. In Comparative Example 2, 5 parts by mass of a light absorber (LA-31: manufactured by ADEKA Corporation) was mixed in the conductive adhesive layer. The other composition is the same as that of the conductive adhesive layer of Example 1.

[Comparative Example 3]
In Comparative Example 3, an anisotropic conductive film provided with a 20 μm-thick binder resin layer in which a 10 μm-thick conductive adhesive layer and a 10 μm-thick insulating adhesive layer were laminated. The composition of the conductive adhesive layer is the same as that of the conductive adhesive layer of Example 1. The insulating adhesive layer does not contain a cationic photopolymerization initiator. Other composition of the insulating adhesive layer is the same as that of the insulating adhesive layer of Example 1.

[Comparative Example 4]
In Comparative Example 4, an anisotropic conductive film including a 20 μm thick binder resin layer in which a 10 μm thick conductive adhesive layer and a 10 μm thick insulating adhesive layer were laminated was used. The conductive adhesive layer did not contain a photocationic polymerization initiator, and 5 parts by mass of a light absorber (LA-31: manufactured by ADEKA Corporation) was blended. Other formulations of the conductive adhesive layer are the same as those of the conductive adhesive layer of Example 1. The insulating adhesive layer does not contain a light absorbing agent. Other composition of the insulating adhesive layer is the same as that of the insulating adhesive layer of Example 1.

[Comparative Example 5]
In Comparative Example 5, an anisotropic conductive film including a 20 μm thick binder resin layer in which a 10 μm thick conductive adhesive layer and a 10 μm thick insulating adhesive layer were laminated was used. The conductive adhesive layer was blended with 5 parts by mass of a light absorber (LA-31: manufactured by ADEKA Corporation). Other formulations of the conductive adhesive layer are the same as those of the conductive adhesive layer of Example 1. The insulating adhesive layer does not contain a light absorbing agent. Other composition of the insulating adhesive layer is the same as that of the insulating adhesive layer of Example 1.

[Comparative Example 6]
In Comparative Example 6, an anisotropic conductive film provided with a 11 μm thick binder resin layer on which a 10 μm thick conductive adhesive layer and a 1 μm thick insulating adhesive layer were laminated was used. The composition of the conductive adhesive layer and the insulating adhesive layer in Comparative Example 6 is the same as in Example 1.

[Measurement of average number of captured particles]
The supplementary number of the crushed conductive particles on the IC bumps of the connection body samples according to the above Examples and Comparative Examples was confirmed using a microscope. Then, the average number of trapped particles of the number of bumps 30 (N = 30) was calculated.

[Measurement of conduction resistance]
With respect to the connection sample according to each of the above Examples and Comparative Examples, the conduction resistance (Ω) was measured at the initial connection and after the reliability test using a digital multimeter. As shown in FIG. 6, the measurement of the continuity resistance is performed by connecting a digital multimeter to the continuity measurement wiring 43 of the evaluation base material (B) connected to the bumps 42 of the evaluation IC (B), so-called four terminals. The conduction resistance was measured by a method (set voltage: 50 V). The conditions for the reliability test were 85 ° C. and 85% RH 500 hr.

[Average number of captured particles]
As shown in Table 1, in Examples 1 to 3 and Comparative Examples 3 and 6, the average number of supplemented particles exceeded 40, and good results were obtained. This is because the light-absorbing agent is contained in the insulating adhesive layer, and the light-absorbing agent is not contained in the conductive adhesive layer or is smaller than the light absorbing agent contained in the insulating adhesive layer. Since the amount of light absorber was mixed, the light absorber of the insulating adhesive layer was reacted by pressing the IC for evaluation and irradiating with ultraviolet light, and the binder resin of the insulating adhesive layer was generated by generating heat. Is melted, and the photopolymerization initiator of the conductive adhesive layer reacts and the binder resin is pressed while being cured.
That is, in Examples 1 to 3 and Comparative Examples 3 and 6, the thickness of the insulating adhesive layer (5 μm, 10 μm, or 1 μm) in which the IC bump was melted can be pushed in, and the conductivity at which the curing reaction proceeds In the adhesive layer, the flow of the resin is suppressed, and the conductive particles are prevented from flowing out from the lower portion, which is the connection portion of the IC bump. Thereby, in the connection body samples according to Examples 1 to 3 and Comparative Examples 3 and 6, many conductive particles could be captured by the IC bumps.

  In addition, when the binder resin of the insulating adhesive layer in which the resin is melted flows, the binder resin of the conductive adhesive layer also flows due to the effect of the flowing resin of the insulating adhesive layer, and the conductive particles may flow out. That is, the conductive particles may move to the side of the IC bump and may not be captured by the IC bump. However, in Examples 2 and 3 and Comparative Example 6, since the thickness of the insulating adhesive layer was formed smaller than the thickness of the conductive adhesive layer, the conductivity of the insulating adhesive layer caused by the flow of the resin was reduced. Outflow of the conductive particles hardly occurs, and it is possible to prevent a decrease in the average trapped number of the conductive particles.

  On the other hand, in Comparative Example 1, since the IC bumps need to push through the conductive adhesive layer having a thickness of 20 μm, compared to Examples 1 to 3 which push through the conductive adhesive layer having a thickness of 10 μm. Then, the movement of the binder resin increases, and the conductive particles flow out from the lower part of the IC bump. For this reason, the number of particles captured by the IC bumps was reduced to about 30 as compared with Examples 1 to 3.

  In Comparative Example 2, in addition to the same phenomenon as in Comparative Example 1, the light absorbing agent was added to the conductive adhesive layer. Melting of the binder resin was promoted. For this reason, the binder resin of the conductive adhesive layer flows more greatly than in Comparative Example 1, and the outflow of the conductive particles from the lower part of the IC bump further proceeds, and the number of particles captured by the IC bump drops to about 15 particles. .

  In Comparative Example 4, in addition to the heat generated by blending the light-absorbing agent in the conductive adhesive layer, no curing reaction was caused by irradiation with ultraviolet light because no photopolymerization initiator was blended. The flow of the resin accompanying the melting of the binder resin in the layer increased. For this reason, the outflow of the conductive particles from the lower part of the IC bump progressed, and the number of particles captured by the IC bump dropped to less than 20.

  Also in Comparative Example 5, since the light absorbing agent was added to the conductive adhesive layer, the light absorbing agent generated heat by irradiation with ultraviolet light, and the melting of the binder resin of the conductive adhesive layer was promoted. For this reason, the binder resin of the conductive adhesive layer flows greatly due to the pushing of the IC bumps, and the outflow of the conductive particles from the lower part of the IC bumps proceeds, and the number of particles captured by the IC bumps drops to about 20. Was.

[Conduction resistance value]
As shown in Table 1, in the connection body samples according to Examples 1 to 3, good results were obtained both in the initial stage and in the conduction resistance value after the reliability test (initial: about 1Ω, after the reliability test: less than 10Ω). . This is because a large amount of conductive particles can be captured by the IC bump, and a resin equivalent to the height of the IC bump (10 μm) is filled between the evaluation IC and the evaluation substrate and cured, so that good connection is achieved. Because reliability was obtained.

  On the other hand, in the connection body samples according to Comparative Examples 1, 2, and 5, the connection reliability was slightly inferior to Examples 1 to 3 (initial: 1.5 to 1.9Ω, reliability test). After: about 11Ω). This is because the number of conductive particles captured by the IC bumps is slightly reduced as compared with Examples 1 to 3 (about 15 to 30), and the resin corresponding to the height of the IC bumps is located between the evaluation IC and the evaluation substrate. And cured.

  In the connection body samples according to Comparative Examples 3 and 4, the connection reliability was further deteriorated as compared with Comparative Examples 1, 2, and 5 (initial: 1.2 to 3.5Ω, after the reliability test: about 20Ω). . This is because in Comparative Example 3, the photopolymerization initiator was not added to the insulating adhesive layer, and the resin flowed out without curing, and the resin corresponding to the height of the IC bumps was placed between the evaluation IC and the evaluation substrate. Because it was not filled. Similarly, in Comparative Example 4, since the photopolymerization initiator was not blended in the conductive adhesive layer, the binder resin flowed out without being cured, and the resin equivalent to the height of the IC bumps was used as the evaluation IC and the evaluation substrate. Because it was not filled in between.

  The connector sample according to Comparative Example 6 has a thickness of the insulating adhesive layer of 1 μm and a thin thickness of 11 μm even when the thickness of the conductive adhesive layer is added. Insufficient thickness to fill and cure the binder resin between the evaluation IC and the evaluation substrate for a height equal to the height and the conduction reliability deteriorated (initial: 1.9Ω, after reliability test: 15) .8Ω).

Reference Signs List 1 anisotropic conductive film (photo-curing anisotropic conductive adhesive), 2 release film, 4 conductive particles, 5 conductive adhesive layer, 6 insulating adhesive layer, 10 liquid crystal display panel, 11, 12 transparent Substrate, 13 seal, 14 liquid crystal material, 15 panel display part, 16, 17 transparent electrode, 17a terminal part, 18 liquid crystal drive IC (electronic part), 19 electrode terminal, 20 COG mounting part, 21 flexible substrate (electronic part) , 22 FOG mounting part, 25, 26 polarizing plate, 27 thick film, 30 connecting device, 31 stage, 33 thermocompression bonding tool (crimping tool), 35 UV irradiator

Claims (9)

A photocurable anisotropic conductive adhesive that is cured by irradiation with ultraviolet light,
Having a conductive adhesive layer and an insulating adhesive layer,
The conductive adhesive layer contains a film-forming resin, a photopolymerizable compound, a photopolymerization initiator, and conductive particles,
The insulating adhesive layer contains a film-forming resin, a photopolymerizable compound, a photopolymerization initiator, and a light absorber ,
The light absorption peak wavelength of the light absorber is 20 nm or more larger than the light absorption peak wavelength of the photopolymerization initiator, and the light absorption peak wavelength of the light absorber is 320 nm to 360 nm. A light- curing anisotropic conductive adhesive having a light absorption peak wavelength of 290 nm to 330 nm .   The photocurable anisotropic conductive adhesive according to claim 1, wherein the conductive adhesive layer further contains a light absorber in an amount smaller than the light absorber contained in the insulating adhesive layer. The thickness of the insulating adhesive layer, the light-curable anisotropic conductive adhesive according to any one of the thin Claim 1 or 2 than the thickness of the conductive adhesive layer. A method of manufacturing a connection body,
A step of disposing an electronic component on a transparent substrate mounted on a stage via a photocurable anisotropic conductive adhesive that is cured by irradiation with ultraviolet light,
While pressing the electronic component against the transparent substrate by a pressure tool, a step of performing light irradiation on the photocurable anisotropic conductive adhesive by a light irradiator,
The photocurable anisotropic conductive adhesive,
Film-forming resin, a photopolymerizable compound, a photopolymerization initiator, and a conductive adhesive layer containing conductive particles,
A film-forming resin, a photopolymerizable compound, a photopolymerization initiator, and an insulating adhesive layer containing a light absorber ,
The light absorption peak wavelength of the light absorber is 20 nm or more larger than the light absorption peak wavelength of the photopolymerization initiator, and the light absorption peak wavelength of the light absorber is 320 nm to 360 nm. The method for manufacturing a connector , wherein the light absorption peak wavelength of the connector is 290 nm to 330 nm . The method for manufacturing a connector according to claim 4, wherein the conductive adhesive layer further contains a light absorber in an amount smaller than the light absorber contained in the insulating adhesive layer. The light-curable anisotropic conductive adhesive, the manufacturing method of the connection of any one of claims 4 or 5 having a height thicker than the thickness of the connection terminal of the electronic component. A method of connecting electronic components,
A step of disposing an electronic component on a transparent substrate mounted on a stage via a photocurable anisotropic conductive adhesive that is cured by irradiation with ultraviolet light,
While pressing the electronic component against the transparent substrate by a pressure tool, a step of performing light irradiation on the photocurable anisotropic conductive adhesive by a light irradiator,
The photocurable anisotropic conductive adhesive,
Film-forming resin, a photopolymerizable compound, a photopolymerization initiator, and a conductive adhesive layer containing conductive particles,
A film-forming resin, a photopolymerizable compound, a photopolymerization initiator, and an insulating adhesive layer containing a light absorber ,
The light absorption peak wavelength of the light absorber is 20 nm or more larger than the light absorption peak wavelength of the photopolymerization initiator, and the light absorption peak wavelength of the light absorber is 320 nm to 360 nm. The method for connecting an electronic component , wherein the light absorption peak wavelength of the electronic component is 290 nm to 330 nm . The method for connecting electronic components according to claim 7, wherein the conductive adhesive layer further contains a light absorber in an amount smaller than the light absorber contained in the insulating adhesive layer. The light-curable anisotropic conductive adhesive, the connection method of the electronic component of any one of claims 7 or 8 having a height thicker than the thickness of the connection terminal of the electronic component.

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