TW202223030A - Anisotropic conductive film - Google Patents

Abstract

This anisotropic electroconductive film has a structure such that a base material film, an electroconductive particle-containing layer in which electroconductive particles are supported in a binder resin layer, and an insulating resin layer are laminated in this order, in which the insulating resin layer comprises a polyvinyl acetal resin having a glass transition temperature of 70 DEG C to 110 DEG C, inclusive. The polyvinyl acetal resin has a degree of acetalization of 60 to 80 mol%, inclusive, and a hydroxyl group amount of 20 to 40 mol%, inclusive, and an acetyl group amount of 10 mol% or less.

Description

Anisotropic Conductive Film

The present invention relates to an anisotropic conductive film suitable for anisotropic conductive connection between a display panel (DP) and a flexible circuit substrate (FPC).

Conventionally, when a display device such as a liquid crystal display device or an organic EL display device is manufactured, a display panel and a flexible circuit substrate are anisotropically formed on a glass or optical plastic substrate with an image display element through an anisotropic conductive film. Sexually conductive connection. As shown in FIG. 6 , the anisotropic conductive film 60 has an insulating resin layer 62 formed on a base film 61, and further formed thereon with conductive particles containing conductive particles 64 held in a binder resin layer 63. For the structure of the layer 65, when the above-mentioned anisotropic conductive connection is performed, as shown in FIG. As shown in FIG. 8 , the base film 61 is peeled off to expose the insulating resin layer 62 , and then, as shown in FIG. 9 , the terminal portions 81 of the flexible circuit board 80 and the electrode portions 71 of the display panel 70 are aligned. , the display panel 70 and the flexible circuit board 80 are anisotropically conductively connected, as shown in FIG. 10 , by thermocompression bonding using a thermocompression tool 90 (Patent Document 1).

In recent years, with the requirement to expand the image display area of the display panel, the edge of the electrode portion 71 at the outer edge of the display panel 70 has been narrowed. As a result, it is difficult to remove the conventional anisotropic conductive film 60 of FIG. 6 from its surface. The conductive particle-containing layer 65 is temporarily attached to the electrode portion 71 of the display panel, so an attempt is being made to align with the electrode portion of the display panel after temporarily attaching the anisotropic conductive film to the terminal portion of the flexible circuit substrate. Thermocompression bonding is performed to connect the display panel and the flexible circuit substrate in an anisotropic conductive manner. In this case, the use of an anisotropic conductive film 10 having a structure as shown in FIG. 1 in which a conductive particle-containing layer in which conductive particles 3 are held in a binder resin layer 2 is formed on a base film 1 has been studied. 4. Further, an insulating resin layer 5 having a minimum melt viscosity lower than that of the conductive particle-containing layer 4 is formed thereon. prior art literature Patent Literature

Patent Document 1: International Publication No. 2011/093207

[The problem to be solved by the invention]

However, with regard to the anisotropic conductive film 10 having the configuration shown in FIG. 1, the viscosity is lower than that of the conductive particle-containing layer 4, in other words, the insulating resin layer 5 showing high viscosity is exposed on the surface. When the oriented conductive film is cut into narrow strips, the resin constituting the insulating resin layer 5 adheres to the dicing blade, which may cause the substrate film 1 and the conductive particle-containing layer 4 to peel off when the strip is cut. If it peels in this way, even if it tries to wind up the anisotropic conductive film on the core of the reel with a pair of flanges attached to the core and process it into a package for storage, it cannot be processed into a package. In particular, due to the narrowing of the edge in recent years, when an anisotropic conductive film with a wider width is to be cut into long strips with a width of 0.4 mm or less, the substrate film 1 and the conductive particle-containing layer exist when cutting the long strips. 4 The problem of frequent peeling and the fact that it cannot be cut into long strips. In addition, even if the base film 1 and the conductive particle-containing layer 4 are not peeled off when cut into a long strip, there are cases where cut sag occurs on the cut surface of the insulating resin layer 5 exposed on the surface of the anisotropic conductive film 10 . Alternatively, after being processed into a package, the insulating resin layer 5 is deformed by a creep phenomenon due to the influence of the internal stress generated in the package or the storage temperature. In this way, if cut sag or deformation of the insulating resin layer 5 occurs on the cut surface of the insulating resin layer 5, even if the anisotropic conductive film can be processed into a package, there are cases where, depending on the storage temperature or storage time, The insulating resin penetrates between the anisotropic conductive films to cause blocking between the anisotropic conductive films, or the anisotropic conductive film adheres to the flange of the package body, resulting in that it cannot be properly pulled out from the package body Phenomenon of anisotropic conductive film (pull-out sticking phenomenon).

An object of the present invention is to solve the conventional problem and to cut an anisotropic conductive film having a structure in which a base film, a conductive particle-containing layer in which conductive particles are held in a binder resin layer, and an insulating resin layer are laminated in this order. It can be made into strips with narrow width (for example, the width is less than 0.4 mm), which is suitable for the anisotropic conductive connection between the display panel and the flexible circuit substrate. When the conductive film is processed into a package, the occurrence of pull-out blocking is also greatly suppressed. [Technical means to solve the problem]

The present inventors discovered that the above-mentioned object can be achieved by making the insulating resin layer of the anisotropic conductive film contain a polyvinyl acetal resin having a glass transition temperature in a specific range, and completed the present invention.

That is, the present invention provides an anisotropic conductive film obtained by laminating a base film, a conductive particle-containing layer holding conductive particles in a binder resin layer, and an insulating resin layer in this order, wherein the insulating resin layer Contains a polyvinyl acetal resin having a glass transition temperature of 70°C or more and 110°C or less.

Furthermore, the present invention provides a connection structure in which a first electron is connected to a layered body of a conductive particle-containing layer and an insulating resin layer remaining after peeling and removing the base film from the anisotropic conductive film of the present invention. The component is anisotropically conductively connected to the second electronic component. In this connection structure, it is preferable that the 1st electronic component is a display panel, the 2nd electronic component is a flexible circuit board, and the conductive particle containing layer is arrange|positioned at the display panel side.

Furthermore, the present invention also provides a method for producing a connection structure, which comprises "the laminate of the conductive particle-containing layer and the insulating resin layer remaining after peeling and removing the base film from the anisotropic conductive film of the present invention". The first electronic component and the second electronic component are anisotropically conductively connected. In this manufacturing method, it is preferable that the first electronic component is a display panel, the second electronic component is a flexible circuit board, and the conductive particle-containing layer is arranged on the display panel side to perform anisotropic conductive connection. [Effect of invention]

The anisotropic conductive film of the present invention has a structure in which a base film, a conductive particle-containing layer holding conductive particles in a binder resin layer, and an insulating resin layer are laminated in this order. Therefore, since the insulating resin layer is exposed on the surface, the anisotropic conductive film can be temporarily attached to the flexible circuit board from the insulating resin layer side. Moreover, the insulating resin layer contains the polyvinyl acetal resin which has a glass transition temperature of 70 degreeC or more and 110 degrees C or less. Therefore, when the anisotropic conductive film is cut into long strips with a narrow width of, for example, 0.4 mm or less, the insulating resin layer can be suppressed from being cut and sag, and the cutting adaptability of the anisotropic conductive film can be improved. When the anisotropic conductive film is processed into a package, the occurrence of pull-out blocking can also be greatly suppressed.

Hereinafter, the anisotropic conductive film of the present invention and its manufacturing method will be described in detail with reference to the drawings. In addition, in each figure, the same code|symbol represents the same or equivalent component.

＜＜Anisotropic Conductive Film＞＞ As shown in FIG. 1 , the anisotropic conductive film 10 of the present invention includes a substrate film 1 , a conductive particle-containing layer 4 holding conductive particles 3 in a binder resin layer 2 , and an insulating resin layer 5 in this order. structure. The anisotropic conductive film 10 of the present invention is characterized in that the insulating resin layer 5 contains a polyvinyl acetal resin having a glass transition temperature of 70° C. or higher and 110° C. or lower. Hereinafter, each layer constituting the anisotropic conductive film 10 will be described in detail.

<Insulating resin layer 5> The insulating resin layer 5 constituting the anisotropic conductive film 10 is a layer in which a flexible circuit board and a hard material made of glass or optical plastic are bonded by thermocompression through the anisotropic conductive film 10 . When the display panel is anisotropically conductively connected, it is temporarily attached to the layer on the side of the flexible circuit substrate. As described below, since the insulating resin layer 5 is designed to have a lower minimum melt viscosity than the conductive particle-containing layer, when the anisotropic conductive film is applied to anisotropic conductive connections, the conductive particle-containing layer is less likely to undergo anisotropy. The conductive connection is moved between the opposing electrodes to ensure particle capture of the conductive particles, and the insulating resin layer showing a relatively low minimum melt viscosity is made to flow and protrude from the opposing electrodes to form a protruding portion. To improve the bonding strength of the anisotropic conductive connection. In addition, the flow of the insulating resin layer 5 can ensure that the conductive particles are pressed into the electrodes during anisotropic conductive connection, which also contributes to the improvement of conduction reliability. Due to the existence of the insulating resin layer 5, the narrowing of the electrode portion at the outer edge of the display panel can also be dealt with.

(polyvinyl acetal resin) The reason why the insulating resin layer 5 contains a polyvinyl acetal resin exhibiting a glass transition temperature of 70° C. or more and 110° C. or less, preferably 80° C. or more and 110° C. or less is that when the anisotropic conductive film is cut into, for example, In the case of long strips with a narrow width of 0.4 mm or less, the insulating resin layer is suppressed from being cut and sagged, the cutting adaptability of the anisotropic conductive film is improved, and even when the anisotropic conductive film is made into a roll body, The deformation of the insulating resin layer 5 due to the internal stress of the package is also suppressed. Furthermore, if the glass transition temperature is less than 70° C., it may be difficult to suppress the deformation of the insulating resin layer 5 . In the case of anisotropic conductive connection, there is a tendency for poor mounting such as poor conduction due to a decrease in the press-fit of conductive particles. The glass transition temperature can be measured by known differential scanning calorimetry.

The polyvinyl acetal resin is a compound obtained by subjecting polyvinyl alcohol and an aldehyde compound to an acetalization reaction, and usually has an acetyl group and a hydroxyl group in addition to the acetal group. Here, the acetal group is formed by bonding two vinyl alcohol units to one molecule of aldehyde compound, one acetyl group is bonded to one vinyl alcohol unit, and one hydroxyl group corresponds to one free vinyl alcohol unit. Therefore, when the degree of polymerization of the acetal group, acetyl group, and hydroxyl group in the polyvinyl acetal resin is set to 1, m, and n, respectively, the content of these groups is calculated according to the following formula, which is specified in the present invention. The index of the polyvinyl acetal resin that can be preferably used.

Amount of acetal group (degree of acetalization: mole %) = {l/(l+m+n)}×100 Acetyl amount (mol%) = {m/(l+m+n)}×100 Amount of hydroxyl groups (mol%)={n/(l+m+n)}×100

In the anisotropic conductive film of the present invention, as the polyvinyl acetal resin contained in the insulating resin layer 5, the degree of acetalization used is preferably 60 mol % or more and 80 mol % or less, more preferably 65 mol %. Ear% above 75 mole% below. If the acetalization degree is lower than this range, the compatibility with other resin components constituting the insulating resin layer 5 tends to decrease, and if the acetalization degree exceeds this range, the insulating resin layer 5 may be excessively softened , the trend that the expected addition effect of polyvinyl acetal resin cannot be obtained.

Moreover, as the polyvinyl acetal resin contained in the insulating resin layer 5, the hydroxyl group content is preferably 20 mol % or more and 40 mol % or less, more preferably 25 mol % or more and 35 mol % or less. If the amount of hydroxyl groups is less than this range, the film-forming properties of the composition for forming an insulating resin layer used in the production of the insulating resin layer 5 tend to decrease, and if the amount of hydroxyl groups exceeds this range, the insulating resin tends to The film strength of the layer 5 is too high, and when the anisotropic conductive connection is performed by the anisotropic conductive film having the insulating resin layer 5, the indentability of the conductive particles is lowered, resulting in installation failures such as poor conduction.

Moreover, as the polyvinyl acetal resin contained in the insulating resin layer 5, it is preferable that the content of an acetyl group is 10 mol% or less, and it is more preferable that it is 3 mol% or less. When the acetyl group content exceeds this range, the glass transition temperature of the insulating resin layer 5 tends to decrease, the cutting adaptability of the anisotropic conductive film decreases, and it becomes difficult to suppress the deformation of the insulating resin layer 5 . Furthermore, in order to maintain good coating properties without excessively increasing the solution viscosity of the composition for forming an insulating resin layer, the amount of acetyl groups is preferably 0.5 mol % or more.

As a specific example of a polyvinyl acetal resin, a polyvinyl formal resin, a polyvinyl acetal resin, a polyvinyl acetal resin, a polyvinyl butyral resin, etc. are mentioned. Among them, polyvinyl butyral resin, which is easy to obtain and has relatively high chemical stability, is preferred.

Furthermore, with regard to the weight average molecular weight of the polyvinyl acetal resin, if the weight average molecular weight is too low, the solution viscosity of the composition for forming an insulating resin layer decreases, resulting in a decrease in coating properties, so it is preferably 1.0×10. ³ or more, more preferably 1.0×10 ⁴ or more; if the weight-average molecular weight is too high, there is a tendency that the solution viscosity of the composition for forming an insulating resin layer increases excessively, resulting in a decrease in coating properties, and further, by When the anisotropic conductive film having the insulating resin layer 5 is anisotropically conductively connected, since the indentability of the conductive particles is lowered, resulting in poor conduction and other mounting defects, it is preferably 1.0×10 ⁶ or less, more preferably 1.0 ×10 ⁵ or less.

Regarding the content of the polyvinyl acetal resin in the insulating resin layer 5, if the content is too small, the anisotropic conductive film having a narrow width (for example, a width of 0.4 mm or less) of the insulating resin layer 5 is processed into a In the case of a package body, since it is difficult to exhibit the blocking inhibitory effect, it is preferably 1 mass % or more, more preferably 3 mass % or more; When the oriented conductive film is anisotropically conductively connected, it is preferable that it is 20 mass % or less, and more preferably 10 mass % or less, since there is a tendency for mounting failures such as conduction failure due to a decrease in the indentability of the conductive particles.

(Ingredients other than polyvinyl acetal resin) The insulating resin layer 5 of the anisotropic conductive film 10 of the present invention preferably contains a film-forming resin, a polymerizable acrylic compound, and a polymerization initiator in addition to the polyvinyl acetal resin.

(Film-forming resin) The film-forming resin is one that imparts layer shape stability to the insulating resin layer 5, and can be appropriately selected from known film-forming resins and used. For example, phenoxy-based resins, epoxy-based resins, polyester-based resins, urethane-based resins, butadiene-based resins, polyimide-based resins, polyamide-based resins, and the like can be used. Among them, phenoxy-based resins are preferred in terms of imparting good high-temperature and high-humidity reliability to the anisotropic conductive connection by the anisotropic conductive film having the insulating resin layer 5, and particularly preferred It is a bisphenol A type epoxy phenoxy resin (eg YP-50, Nippon Steel Chemical Materials Co., Ltd.).

The content of the film-forming resin in the insulating resin layer 5 is preferably 10% by mass or more, and more preferably 30% by mass or more, if the content is too small, it is difficult to form a film, and if the content is too large, there may be When the anisotropic conductive connection is performed by the anisotropic conductive film having the insulating resin layer 5, since the indentability of the conductive particles is lowered, the tendency of installation failure such as poor conduction is caused, so it is preferably 70% by mass or less, More preferably, it is 50 mass % or less.

(polymerizable acrylic compound) The polymerizable acrylic compound is a polymerizable component of the composition for forming an insulating resin layer, a component that imparts mechanical strength and adhesive strength to the insulating resin layer 5 after polymerization, and has at least one acryl group or a methacryl group (hereinafter referred to as (meth)acryloyl) compounds. The polymerizable acrylic compound has two or more, preferably two (meth)acryloyl groups, in order to impart good conduction reliability to the anisotropic conductive connection by the anisotropic conductive film.

Specific examples of the polymerizable acrylic compound include polyethylene glycol diacrylate, phosphate acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, acrylic acid Isobutyl, tertiary butyl acrylate, isooctyl acrylate, bisphenoxyethanol, diacrylate, 2-acryloyloxyethyl succinate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, Tricyclodecane dimethanol dimethacrylate, cyclohexyl acrylate, tris(2-hydroxyethyl)trimeric isocyanate triacrylate, tetrahydrofurfuryl acrylate, diglycidyl ether phthalate acrylate , ethoxylated bisphenol A dimethacrylate, bisphenol A type epoxy acrylate, urethane acrylate, epoxy acrylate, etc., and their corresponding (meth)acrylates.

Regarding the content of the polymerizable acrylic compound in the insulating resin layer 5 , if the content is too small, the conduction reliability may be lowered when the anisotropic conductive connection is performed by the anisotropic conductive film having the insulating resin layer 5 . Therefore, it is preferably 20 mass % or more, more preferably 30 mass % or more; if the content is too large, the adhesive strength of the insulating resin layer 5 tends to decrease, so it is preferably 70 mass % or less, more preferably 60 mass % or less.

(polymerization initiator) The polymerization initiator is a compound for initiating the polymerization of the polymerizable acrylic compound, and can be appropriately selected from known radical polymerization initiators, cationic polymerization initiators, and anionic polymerization initiators, and among them, the preferred Radical polymerization initiators, especially organic peroxides. As the organic peroxide, a known organic peroxide can be appropriately selected. For example, lauryl peroxide, butyl peroxide, benzyl peroxide, benzyl peroxide, etc. are mentioned.

The content of the polymerization initiator in the insulating resin layer 5 can be appropriately determined according to the type or blending amount of the polymerizable acrylic compound, the type of the polymerization initiator, and the like.

(insulating filler) An insulating filler may be contained in the insulating resin layer 5 to adjust the melt viscosity. Examples of the insulating filler include silica powder, alumina powder, and the like. Preferably, the insulating filler is a fine filler with a particle size of 5 to 1000 nm. Furthermore, the content of the insulating filler in the insulating resin layer 5 can be appropriately determined according to the required melt viscosity, the type or particle size of the insulating filler, the type or blending amount of other components, and the like.

In addition, the insulating resin layer 5 may contain a softener, an accelerator, an antiaging agent, a colorant (pigment, dye), an organic solvent, an ion scavenger, and the like.

In order to temporarily stick to the flexible circuit board during anisotropic conductive connection between the display panel and the flexible circuit board, the anisotropic conduction through the anisotropic conductive film having the insulating resin layer 5 The connection provides good connection reliability, and the thickness of the insulating resin layer 5 is preferably 3 μm or more, more preferably 5 μm or more, and preferably 20 μm or less, more preferably 15 μm or less.

<Conductive particle-containing layer 4> The conductive particle-containing layer 4 has a structure in which the conductive particles 3 are held in the binder resin layer 2 , and the holding state of the conductive particles 3 is not particularly limited. For example, the conductive particles 3 may be randomly dispersed in the binder resin layer 2 . The conductive particles 3 can also be regularly arranged in the plane direction of the adhesive resin layer 2, for example, they can be arranged in a lattice shape, and in this case, they can be arranged regularly in a single layer.

(Adhesive resin layer 2) The binder resin layer 2 constituting the conductive particle-containing layer 4 may contain the same constituents as the insulating resin layer 5 (ie, film-forming resin, polymerizable acrylic compound, and polymerization initiator) except for the polyvinyl acetal resin, In order to improve the film strength, it is preferable to necessarily contain a compound having two or more (meth)acryloyl groups as a polymerizable acrylic compound. Furthermore, as long as the effect of the present invention is not impaired, a small amount of polyvinyl acetal resin may be contained in the adhesive resin layer 2, but from the viewpoints of initial conduction reliability and adhesive strength, it is preferable not to contain polyvinyl acetal resin. aldehyde resin.

The content of the film-forming resin in the adhesive resin layer 2 is preferably 10 mass % or more, and more preferably 30 mass % or more, if the content is too small, it is difficult to form a film; When the anisotropic conductive connection is performed by the anisotropic conductive film having the adhesive resin layer 2, since the indentability of the conductive particles is lowered, the tendency of installation failure such as poor conduction is caused, so it is preferably 70% by mass or less, More preferably, it is 50 mass % or less.

Regarding the content of the polymerizable acrylic compound in the adhesive resin layer 2, if the content is too small, the conduction reliability may be lowered when the anisotropic conductive connection is performed by the anisotropic conductive film having the adhesive resin layer 2. Therefore, it is preferably 20 mass% or more, more preferably 30 mass% or more; if the content is too large, the adhesive strength of the adhesive resin layer 2 tends to decrease, so it is preferably 70 mass% or less, more preferably 60 mass % or less.

(polymerization initiator) The content of the polymerization initiator in the adhesive resin layer 2 can be appropriately determined according to the type or blending amount of the polymerizable acrylic compound, the type of the polymerization initiator, and the like.

(insulating filler) The adhesive resin layer 2 may also contain insulating fillers to adjust the melt viscosity. Examples of the insulating filler include silica powder, alumina powder, and the like. Preferably, the insulating filler is a fine filler with a particle size of 5 to 1000 nm. Furthermore, the content of the insulating filler in the adhesive resin layer 2 can be appropriately determined according to the required melt viscosity, the type or particle size of the insulating filler, the type or blending amount of other components, and the like.

In addition, a softener, an accelerator, an antiaging agent, a coloring agent (pigment, dye), an organic solvent, an ion scavenger, etc. may be contained in the adhesive resin layer 2.

The layer thickness of the conductive particle-containing layer 4 also depends on the particle size of the conductive particles, preferably 1 μm or more, more preferably 3 μm or more, and preferably 6 μm or less, more preferably 5 μm or less, so as to facilitate display During the anisotropic conductive connection between the panel and the flexible circuit board, the anisotropic conductive connection with the display panel can be assured.

等樹脂粒子之表面實施了鍍鎳之金屬被覆樹脂粒子等。亦可併用兩種以上。 (Conductive Particles 3 ) As the conductive particles 3 , conductive particles used in conventional anisotropic conductive films can be appropriately selected and used, and metal or alloy particles such as nickel particles, solder particles, p-benzoguanidine can be used.

Metal-coated resin particles, etc., in which nickel plating is performed on the surface of the resin particles, etc. Two or more types may be used in combination.

The average particle diameter of the conductive particles 3 is set to a size suitable for the anisotropic conductive connection between the display panel and the flexible circuit board. It is preferably 1 μm or more, more preferably 2 μm or more, and more preferably 10 μm or less, more preferably 4 μm or less. The average particle diameter can be measured using a general particle size distribution measuring apparatus, for example, a particle size distribution measuring apparatus specified by a trade name: FPIA-3000 (Malvern Instruments). Preferably, the number of samples to be measured for particle diameter is 200 or more, preferably 1000 or more, and more preferably 5000 or more during measurement. In addition, the average particle diameter of the conductive particles can also be obtained by using a metallographic microscope or a scanning electron microscope, without using a general particle size distribution measuring device, and dispersing the conductive particles on a flat plate such as a glass plate. The sample or the sample obtained by kneading it into the curable resin composition and making it monodisperse and coating it is observed to obtain the particle diameter of a plurality of conductive particles, and the arithmetic average of the particle diameters of the obtained plurality of conductive particles is carried out.

In the case of evaluating the content of the conductive particles 3 in the conductive particle-containing layer 4 with the particle surface density [pcs/mm ² ] as an index, if the particle surface density is too small, the anisotropic conductive film in the anisotropic conductive film The particles captured between the opposing electrodes at the connection portion are insufficient and the resistance is high. If the surface density of the particles is too large, there is a risk of particle connection (short circuit) between the wirings, so it is preferably 4000 pcs/mm ² or more, more preferably It is 8000 pcs/mm ² or more, and preferably 20,000 pcs/mm ² or less, more preferably 16,000 pcs/mm ² or less.

(minimum melt viscosity) It is preferable that the minimum melt viscosity of the insulating resin layer 5 of the anisotropic conductive film 10 of the present invention is lower than the minimum melt viscosity of the conductive particle-containing layer 4 in order to capture particles. When evaluated by the lowest melt viscosity ratio, it is preferable that insulating resin layer 5 : conductive particle-containing layer 4 = 1:40 to 1:2, and more preferably insulating resin layer 5 : conductive particle-containing layer 4 = 1 : 20 to 1:5. In addition, the minimum melt viscosity can be measured by a well-known method. For example, it can be obtained by using a rotational rheometer (manufactured by TA instruments), with a measurement pressure of 5 g fixed, and using a measurement plate with a diameter of 8 mm. Within the temperature range, the temperature increase rate was set to 10° C./min, the measurement frequency was set to 10 Hz, and the load fluctuation on the measurement plate was set to 5 g.

(Substrate film 1) The base film 1 is a film used to improve the shape retention or handling characteristics of the anisotropic conductive film 10 during the production or storage of the anisotropic conductive film 10, and is finally removed during the anisotropic conductive connection, and conventionally known ones can be used. base film. For example, if necessary, a polyethylene terephthalate film, a nylon film, a polyimide film, etc., to which a known release agent is applied may be mentioned. Moreover, the thickness of the base film 1 is preferably 20 μm or more, more preferably 35 μm or more, and preferably 100 μm or less, more preferably 60 μm or less.

<Manufacturing method of anisotropic conductive film> The anisotropic conductive film of the present invention can be produced by a known method. For example, when the conductive particles are randomly dispersed in the binder resin layer, the conductive particles are dispersed in the composition for forming the binder resin layer, and the obtained dispersion is applied to the base film, for example, at about 60 The conductive particle-containing layer is formed on the base film by drying in an oven at ~100°C, preferably 70 to 90°C, for 1 minute to 1 hour, preferably about 2 to 10 minutes. The composition for forming an insulating resin layer is coated on another base film, and dried in an oven at, for example, about 60 to 100° C., preferably 70 to 90° C. for 1 minute to 1 hour, preferably about 2 to 10 minutes. , thereby forming an insulating resin layer on the base film. The insulating resin layer was bonded to the above-mentioned conductive particle-containing layer, and the base film was peeled off from the insulating resin layer to obtain an anisotropic conductive film having the structure shown in FIG. 1 .

Furthermore, after forming a binder resin layer containing no conductive particles on the base film, conductive particles can be regularly arranged on the binder resin layer by a known method to form a layer containing conductive particles, and then the insulating layer can be laminated. resin layer.

<How to use anisotropic conductive film> The anisotropic conductive film of the present invention can be used to separate first electronic parts such as glass substrates, plastic substrates, rigid substrates, ceramic substrates, IC modules, display panels, etc., and second electronic parts such as flexible circuit boards by conventional methods. It is preferably used for directional conductive connection. In addition, the electronic components connected by the anisotropic conductive film of this invention are not limited to the above-mentioned electronic components.

Therefore, the present invention includes, as one aspect of the present invention, a connection structure and a method for producing a connection structure, wherein the connection structure is obtained by "peeling and removing the substrate film from the above-mentioned anisotropic conductive film of the present invention. A layered body containing a layer containing conductive particles and an insulating resin layer" is formed by anisotropically conductively connecting the first electronic component and the second electronic component, and the method for producing the above-mentioned connected structure is based on "the anisotropically conductive structure obtained from the above-mentioned invention" The layered body of the conductive particle-containing layer and the insulating resin layer remaining after film peeling and removal of the base film" anisotropically conductively connects the first electronic component and the second electronic component. A preferred connection structure is as follows: the first electronic component is a display panel, the second electronic component is a flexible circuit board, and the conductive particle-containing layer is disposed on the display panel side. In addition, a preferred method of manufacturing the connection structure is as follows: the first electronic component is a display panel, the second electronic component is a flexible circuit board, and the conductive particle-containing layer is arranged on the display panel side to perform anisotropic conduction connect. Below, the manufacturing method of a connection structure is demonstrated based on drawing.

First, the anisotropic conductive film 10 shown in FIG. 1 is prepared. The anisotropic conductive film 10 has a structure in which a conductive particle-containing layer 4 holding conductive particles 3 in a binder resin layer 2 is formed on a base film 1 , and an insulating resin layer 5 is formed thereon.

Next, as shown in FIG. 2, the insulating resin layer 5 of the anisotropic conductive film 10 can be temporarily attached to the terminal portion 81 of the flexible circuit board 80, and as shown in FIG. The conductive particle layer 4 is exposed, and then, as shown in FIG. 4 , the terminal portion 81 of the flexible circuit board 80 and the electrode portion 71 of the display panel 70 are aligned in position, and the thermocompression tool 90 is used to perform thermocompression bonding, thereby 5 , the display panel 70 and the flexible circuit substrate 80 are anisotropically conductively connected. [Example]

Hereinafter, the anisotropic conductive film of the present invention will be described in more detail by way of examples.

Examples 1 to 3, Comparative Examples 1 to 3 Manufacture of anisotropic conductive films (1) Formation of insulating resin layer A composition for forming an insulating resin layer was prepared with the composition shown in Table 1. The composition was coated on a PET (polyethylene terephthalate) film with a film thickness of 50 μm as a base film by a bar coater, dried in an oven at 80°C for 5 minutes, An insulating resin layer with a thickness of 10 μm was formed on the PET film.

(2) Formation of the adhesive resin layer A composition for forming an adhesive resin layer was prepared with the composition shown in Table 1. The composition was coated on a PET (polyethylene terephthalate) film with a film thickness of 50 μm as a base film by a bar coater, dried in an oven at 80°C for 5 minutes, An adhesive resin layer with a thickness of 4 μm was formed on the PET film.

(3) Formation of conductive particle-containing layer The resin for resin molding was applied to a mold provided with approximately cylindrical protrusions having an outer diameter of 3.5 μm and a height of 3.5 μm at a density of 13,000 pieces/mm ² . Resin mold for concave parts corresponding to convex parts. Au/nickel-coated resin particles (AUL703, Sekisui Chemical Industry Co., Ltd.) with an average particle size of 3 μm were filled in the concave part of the resin mold, covered with the adhesive resin layer prepared above, and the conductive particles were heated at 60°C, 0.5 Transfer to the adhesive resin layer under the condition of MPa, and then press the transferred conductive particles into the adhesive resin layer under the conditions of 60-70°C and 0.5 MPa by a flat plate to form a conductive particle-containing layer. The particle surface density of the conductive particles was 13,000 particles/mm ² corresponding to the protrusions.

(4) Processed into anisotropic conductive film An insulating resin layer was placed on the conductive particle-containing layer on the base film, laminated at 40°C and 0.5 MPa, and the base film on the insulating resin layer was peeled off to obtain the anisotropy shown in FIG. 1 . Conductive film (base film/conductive particle-containing layer/insulating resin layer).

＜＜Evaluation＞＞ The anisotropic conductive films prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to (a) cutting suitability evaluation test, (b) pull-out blocking evaluation test, and (c) initial stage as described below. Conduction reliability evaluation test, (d) Adhesion strength evaluation test. The results are shown in Table 1.

(a) Cutting suitability evaluation test The anisotropic conductive films of Examples 1 to 3 and Comparative Examples 1 to 3, each comprising a layer of substrate film/conductive particle-containing layer/insulating resin layer having a thickness of 100 m, were cut into strips with a width of 0.6 mm, and rolled. Take it from a reel to make a package. The package body was observed from the cross-sectional direction with an optical microscope, and the presence or absence of cut sagging was investigated. In addition, the observation of cutting sag was carried out as follows.

That is, the package has a structure in which ACFs (base film/conductive particle-containing layer/insulating resin layer) are stacked from the outer peripheral side to the center. Focusing on one of the stacked ACFs, this is set as the reference ACF, and the adjacent ACF is set as the reference ACF. The inner ACF is set as the 1st ACF, and the ACF closer to the inner side is set as the 2nd ACF. Observe the cross-section of the package at this time (outer peripheral side←･･/standard ACF/1st ACF/2nd ACF/･･ → Center side), the case where the insulating resin layer of the reference ACF does not protrude to the 1st ACF is set as “protruding less than one layer”, and the case where the insulating resin layer protrudes to the 1st ACF but not the 2nd ACF is set as “protruding one layer” More than two layers", the case of protruding to the 2nd ACF and above was regarded as "protruding two layers or more", and the evaluation was performed according to the following criteria. The evaluation result is A or B is ideal.

(Evaluation criteria for cutting suitability) A: Not reaching the first floor B: More than one layer and less than two layers C: more than two layers

(b) Pull-out adhesion evaluation test 100 m of the anisotropic conductive films of Examples 1 to 3 and Comparative Examples 1 to 3 were cut into strips having a width of 0.6 mm, and were wound on a reel to prepare a package. After storing the package in an environment of 20° C. or 27° C. for a predetermined time, the anisotropic conductive film was pulled out from the package, and the presence or absence of blocking was investigated at this time, and the evaluation was performed according to the following criteria. The evaluation result is A or B is ideal.

(Pull out adhesion evaluation criteria) A: When stored at 20°C, blocking occurred after 7 days after storage, and when stored at 27°C, blocking occurred after 4 days after storage. B: When stored at 20°C, blocking occurred after 3 days and less than 7 days after storage, and when stored at 27°C, blocking occurred after 2 days and less than 4 days after storage. C: When stored at 20°C, blocking occurred within 3 days after storage, and when stored at 27°C, blocking occurred within 2 days after storage.

(c) Initial turn-on reliability evaluation test A COF (two-layer polyimide substrate) for evaluation was prepared as a flexible circuit substrate. The wiring pitch was 20 μm, and the wiring was flash-plated tin on Cu with a thickness of 8 μm. The substrate material is a polyimide film with a thickness of 38 μm. This COF for evaluation was anisotropically conductively connected to the glass substrate via the anisotropic conductive film. Specifically, the insulating resin layer of the anisotropic conductive film was temporarily attached to the terminal portion of the COF for evaluation, the base film was peeled off, and the exposed conductive particle-containing layer and the glass substrate (Ti/Al with a thickness of 0.3 μm) were separated. The electrode part of the wiring) is aligned, and the self-evaluation COF side is heated under the conditions of 180 ° C, 3.5 MPa, 6 seconds through a Teflon (registered trademark) buffer film with a thickness of 100 μm using a hot pressing tool. By crimping (tool speed is 10 mm/sec, stage temperature is 40°C), anisotropic conductive connection is performed, and a connection structure is produced. For the obtained connection structure, a digital multimeter (product number: Digital Multimeter 7555, manufactured by Yokogawa Measurement & Instruments Co., Ltd.) was used to measure the connection resistance when a current of 1 mA was flowed by the four-terminal method, and evaluated according to the following criteria. The evaluation result is A or B is ideal.

(Initial turn-on reliability evaluation criteria) A: The case where the on-resistance value is less than 2 Ω. B: The case where the on-resistance value is 2 Ω or more and 4 Ω or less. C: The case where the on-resistance value exceeds 4 Ω.

(d) Adhesion strength evaluation test The same connection structure as the connection structure produced in the above-mentioned initial conduction reliability evaluation test was produced. The COF for evaluation of the produced connecting structure was cut with a width of 1 cm, and a tensile tester (RTC1201, A&D Co., Ltd.) was used, and the COF for evaluation was pulled at an angle of 90° at a speed of 50 mm/sec. The adhesive strength at the time was evaluated according to the following criteria. The evaluation result is A or B is ideal.

(Following Strength Evaluation Criteria) A: The case where the adhesive strength is 8 N or more. B: The case where the subsequent strength is 5 N or more and less than 8 N. C: The following case where the strength did not reach 5 N.

[Table 1] constituents source Properties of Polyvinyl Butyral Insulating resin layer (mixing unit: parts by mass) Conductive particle-containing layer Molar % of hydroxyl Acetyl molar % Acetal group molar % weight average molecular weight Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Examples 1 to 3 Comparative Examples 1 to 3 Bisphenol A epoxy phenoxy resin YP-50, Nippon Steel Chemical Materials Co., Ltd. - - - - 44 44 44 44 54 44 44 Polyvinyl butyral, Tg=66℃ BL-S, Sekisui Chemical Industry Co., Ltd. about 23 about 4 about 72 2.3×10 ⁴ - - - 10 - - - Polyvinyl butyral, Tg=70℃ BL-2H, Sekisui Chemical Industry Co., Ltd. about 30 about 3 about 69 2.8×10 ⁴ - - 10 - - - - Polyvinyl butyral, Tg=80℃ BX-L, Sekisui Chemical Industry Co., Ltd. about 32 about 3 about 67 1.8×10 ⁴ - 10 - - - - - Polyvinyl butyral, Tg=107℃ KS-1, Sekisui Chemical Industry Co., Ltd. about 25 about 3 about 74 2.7×10 ⁴ 10 - - - - - - Polyvinyl butyral, Tg=113℃ KS-5Z, Sekisui Chemical Industry Co., Ltd. about 25 about 3 about 74 13×10 ⁴ - - - - - 10 - Urethane acrylate U-2PPA, Shin Nakamura Chemical Industry Co., Ltd. - - - - twenty four twenty four twenty four twenty four twenty four twenty four 19 Difunctional acrylic monomers A-200, Shin Nakamura Chemical Industry Co., Ltd. - - - - - - - - - - 19 Monofunctional acrylic monomer 4-HBA, Osaka Organic Chemical Industry Co., Ltd. - - - - 12 12 12 12 12 12 10 Phosphate type acrylate PM-2, Nippon Kayaku Co., Ltd. - - - - 2 2 2 2 2 2 2 Dilaurin peroxide NOF CORPORATION - - - - 7 7 7 7 7 7 6 total - - - - 100 100 100 100 100 100 100 The average particle size of the Au/Ni-coated resin particles is 3 μm AUL703, Sekisui Chemical Industry Co., Ltd. - - - - Particle surface density = 13000 pcs/mm ² (a) Evaluation of cutting suitability - - - - A A B C C A - (b) Pull out adhesion evaluation at 20°C - - - - A A B B C A - 27℃ - - - - A B B C C A - (c) Initial turn-on reliability evaluation - - - - A A A A A B - (d) Evaluation of Adhesion Strength - - - - A A A A A C -

According to Table 1, in the case of the anisotropic conductive film of Example 1, the cutting suitability and the pull-out blocking at 20°C and 27°C were both evaluated as A, and the insulating properties of the anisotropic conductive film were evaluated as A. In the initial conduction reliability evaluation and the adhesion strength evaluation of the connection structure produced by temporarily attaching the resin layer to the flexible circuit board side, both were evaluated as A.

In addition, in the case of the anisotropic conductive film of Example 2, the glass transition temperature of the polyvinyl butyral blended in the insulating resin layer was 80°C, so the pull-out blocking evaluation at 27°C was B. .

Furthermore, in the case of the anisotropic conductive film of Example 3, the glass transition temperature of the polyvinyl butyral blended in the insulating resin layer was 70°C, so the pull-out blocking at 20°C and 27°C And the cutting suitability was evaluated as B.

On the other hand, in the case of the anisotropic conductive film of Comparative Example 1, although polyvinyl butyral was blended in the insulating resin layer, polyvinyl butyral having a glass transition temperature of less than 70°C (66°C) was used. Butyraldehyde, the cutting suitability was evaluated as C, and the pull-out adhesion at 20°C was evaluated as B, and the pull-out adhesion at 27°C was evaluated as C.

In the case of the anisotropic conductive film of Comparative Example 2, since polyvinyl butyral was not blended in the insulating resin layer, both cutting suitability and pull-out blocking at 20°C and 27°C were evaluated as C.

In the case of the anisotropic conductive film of Comparative Example 3, although polyvinyl butyral was blended in the insulating resin layer, polyvinyl butyral with a glass transition temperature exceeding 110°C (113°C) was used, so the polyvinyl butyral was used. The cutting suitability and the pull-out blocking at 20°C and 27°C were both rated as A, but for the initial stage of the connection structure produced by temporarily attaching the insulating resin layer of the anisotropic conductive film to the flexible circuit board side The conduction reliability evaluation and the adhesion strength evaluation were evaluated as B and C, respectively. [Industrial Availability]

The anisotropic conductive film of the present invention has a structure in which a base film, a conductive particle-containing layer holding conductive particles in a binder resin layer, and an insulating resin layer are laminated in this order. Therefore, since the insulating resin layer is exposed on the surface, the anisotropic conductive film can be temporarily attached to the flexible circuit board from the insulating resin layer side. Moreover, the insulating resin layer contains the polyvinyl acetal resin which has a glass transition temperature of 70 degreeC or more and 110 degrees C or less. Therefore, even if the anisotropic conductive film is cut into narrow strips, the cutting sag is suppressed, the cutting adaptability is improved, and the occurrence of pull-out sticking can be greatly suppressed even when it is processed into a package. , so it is very suitable for anisotropic conductive connection between the narrow-edge display panel and the flexible circuit substrate.

1,61: Substrate film 2,63: Adhesive resin layer 3,64: Conductive particles 4,65: layer containing conductive particles 5,62: Insulating resin layer 10,60: Anisotropic conductive film 70: Display panel 71: Electrode part 80: Flexible circuit substrate 81: Terminal part 90: Heat Press Tool

1 is a cross-sectional view of an anisotropic conductive film 10 of the present invention. [ Fig. 2 ] An explanatory diagram of a method of manufacturing the connection structure of the present invention. [ Fig. 3 ] An explanatory view of a method of manufacturing the connection structure of the present invention. [ Fig. 4 ] An explanatory diagram of a method of manufacturing the connection structure of the present invention. [ Fig. 5 ] An explanatory diagram of a method of manufacturing the connection structure of the present invention. 6 is a cross-sectional view of a conventional anisotropic conductive film. [ Fig. 7 ] An explanatory diagram of a conventional method for producing a connection structure. [ Fig. 8] Fig. 8 is an explanatory view of a conventional method of manufacturing a connection structure. [ Fig. 9 ] An explanatory diagram of a conventional manufacturing method of a connecting structure. [ Fig. 10 ] An explanatory diagram of a conventional method of manufacturing a connection structure.

Claims (17)

An anisotropic conductive film, which is formed by laminating a base film, a conductive particle-containing layer holding conductive particles in a binder resin layer, and an insulating resin layer in this order, and The insulating resin layer contains a polyvinyl acetal resin having a glass transition temperature of 70°C or more and 110°C or less. The anisotropic conductive film according to claim 1, wherein the glass transition temperature of the polyvinyl acetal resin is 80°C or higher and 110°C or lower. The anisotropic conductive film according to claim 1 or 2, wherein the degree of acetalization of the polyvinyl acetal resin is 60 mol % or more and 80 mol % or less. The anisotropic conductive film according to claim 3, wherein the degree of acetalization of the polyvinyl acetal resin is 65 mol % or more and 75 mol % or less. The anisotropic conductive film according to any one of claims 1 to 4, wherein the amount of hydroxyl groups in the polyvinyl acetal resin is 20 mol % or more and 40 mol % or less. The anisotropic conductive film of claim 5, wherein the amount of hydroxyl groups in the polyvinyl acetal resin is 25 mol % or more and 35 mol % or less. The anisotropic conductive film according to any one of claims 1 to 6, wherein the polyvinyl acetal resin has an acetyl group content of 10 mol % or less. The anisotropic conductive film according to claim 7, wherein the acetyl group content of the polyvinyl acetal resin is 3 mol % or less. The anisotropic conductive film according to any one of claims 1 to 8, wherein the polyvinyl acetal resin is a polyvinyl butyral resin. The anisotropic conductive film according to any one of claims 1 to 9, wherein the weight average molecular weight of the polyvinyl acetal resin is 1.0×10 ³ to 1.0×10 ⁶ . The anisotropic conductive film according to any one of claims 1 to 10, wherein the insulating resin layer further contains a film-forming resin, a polymerizable acrylic compound, and a polymerization initiator. The anisotropic conductive film according to any one of claims 1 to 11, wherein the particle areal density of the conductive particles in the conductive particle-containing layer is 4000 pcs/mm ² to 20000 pcs/mm ² . The anisotropic conductive film according to any one of claims 1 to 12, wherein the minimum melt viscosity of the insulating resin layer is lower than the minimum melt viscosity of the conductive particle-containing layer. A connection structure obtained by anisotropically conductively connecting a first electronic component and a second electronic component via a laminate, the laminate system peeling and removing the base from the anisotropic conductive film of any one of claims 1 to 13 The layered body of the conductive particle-containing layer and the insulating resin layer remaining after the material film. The connection structure of claim 14, wherein the first electronic component is a display panel, the second electronic component is a flexible circuit board, and the conductive particle-containing layer is disposed on the display panel side. A method for producing a connection structure, wherein a first electronic component and a second electronic component are anisotropically conductively connected via a laminated body, the laminated system peeling off the base from the anisotropic conductive film of any one of claims 1 to 13 The layered body of the conductive particle-containing layer and the insulating resin layer remaining after the material film. The manufacturing method of claim 16, wherein the first electronic component is a display panel, the second electronic component is a flexible circuit board, and the conductive particle-containing layer is disposed on the display panel side to perform anisotropic conductive connection.

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