TW201803958A - Anisotropic conductive film, method for manufacturing the same and connection structure - Google Patents

Abstract

An anisotropic conductive film (10) has a structure in which an insulating resin layer (1) and a conductive-particle-containing layer (4) that has a plurality of conductive particles (3) existing therein are layered. The insulating resin layer (1) and the conductive-particle-containing layer (4) are both a photopolymerizable resin composition layer containing a photopolymerizable compound and a photopolymerization initiator. The conductive particles (3) exist in a mutually independent manner when the anisotropic conductive film is viewed in a planar view. The anisotropic conductive film has a transmissivity of at least 40%, in the film thickness direction, for light having a wavelength of 300-400 nm.

Description

Anisotropic conductive film, manufacturing method thereof, and connection structure

The present invention relates to an anisotropic conductive film, a method for manufacturing the same, and a connection structure.

Anisotropic conductive films are widely used when mounting electronic components such as IC chips on transparent substrates for display elements. In recent years, from the viewpoint of application to high-density mounting, in order to improve the capture efficiency of conductive particles or connection reliability, and reduce the occurrence of short circuits. As shown in FIG. 7, an anisotropic conductive film 50 having a two-layer structure is used. The anisotropic conductive film 50 is an insulating resin layer 51 having a relatively thick layer and a low melt viscosity, and the conductive particles 53 are dispersed in the insulation. The conductive adhesive-containing layer 52 is formed by laminating the conductive particle-containing layer 54 with a relatively thin layer and a high melt viscosity.

In addition, in the case where an anisotropic conductive film is used to manufacture a connection structure by anisotropic conductive connection, in order to reduce the manufacturing cost, etc., it is attempted to use a plastic that is more flexible than a glass substrate but has lower heat resistance. The substrate serves as the substrate to be connected. In addition, even in the case of a glass substrate, the reduction in thickness has been promoted. In order to perform mounting at low temperatures, various mounting methods that combine heat and energy rays have been studied. Therefore, the use of light such as ultraviolet rays at low temperatures has been proposed. The photo-cationically polymerizable resin composition that is also polymerized below is used as an insulating adhesive for the anisotropic conductive film. During anisotropic conductive connection, the transparent substrate and the anisotropic conductive film that is semi-hardened by light irradiation are used. While the laminate of the electronic component is heated while being irradiated with ultraviolet rays from the transparent substrate side for formal hardening (Patent Document 1, paragraph 0040), it is considered to apply this technology to the anisotropic conductive film of the above two-layer structure. In this case, the light irradiation for semi-hardening is performed from the relatively thick insulating resin layer side, and the light irradiation for formal hardening is performed from the transparent substrate side (that is, the conductive particle-containing layer side).

However, in the case where the technology of Patent Document 1 is simply applied to the anisotropic conductive film having the above-mentioned two-layer structure, it is unavoidable that light irradiation becomes two stages, and it is expected that the anisotropic conductive connection operation will be complicated and the connection Cost increases.

Therefore, it is attempted to omit the light irradiation from the transparent substrate side while pressurizing the laminated body after the light irradiation with semi-hardening. The difference between the two-layer structure of the laminated system before the polymerization is arranged on the transparent substrate from the insulating resin layer side. The anisotropic conductive film is configured by facing the electronic component and the conductive particle-containing layer side of the anisotropic conductive film.

[Prior technical literature]

[Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2002-97443

However, since a part of the conductive particles dispersed and mixed in the conductive particle-containing layer forms aggregates, there is a concern that the following problem arises: the particles generated in the conductive particle-containing layer are aggregated. The light incident from the transparent substrate side is blocked by the body, and the hardening of the anisotropic conductive film, especially the insulating resin layer becomes uneven. As a result, the particle trapping property is reduced. Depending on the position, the target connection strength may not be guaranteed and the connection is reliable. Sex is also reduced.

The object of the present invention is to use an anisotropic conductive film including an insulating resin layer and a conductive particle-containing layer having a plurality of conductive particles in an insulating adhesive, and anisotropically conductively connect a transparent substrate to an electronic component. , It can make the anisotropic conductive film, especially the insulating resin layer harden non-uniform, and can ensure good particle capture, can ensure the target connection strength at any position, and can prevent the reduction of connection reliability .

The present inventors have found that the insulating resin layer and the conductive particle-containing layer are composed of a layer each containing a photopolymerizable compound and a photopolymerizable resin composition before polymerization of the photopolymerization initiator, and the conductive particles are different in plan view. The tropic conductive films are arranged so as to exist independently of each other, and the film thickness direction transmittance for light having a wavelength of 300 to 400 nm is set to 40% or more, thereby solving the above-mentioned problems and completing the present invention.

That is, the present invention provides an anisotropic conductive film comprising an insulating resin layer and a conductive particle-containing layer in which a plurality of conductive particles are present, and the insulating resin layer and the conductive particle-containing layer each contain a photopolymerizable compound. In the layer of the photopolymerizable resin composition with the photopolymerization initiator, the conductive particles exist independently of each other when the anisotropic conductive film is viewed from the top, and the transmittance in the film thickness direction for light having a wavelength of 300 to 400 nm is 40% or more.

In addition, the present invention provides a manufacturing method which is the above-mentioned method for manufacturing an anisotropic conductive film. The method comprises a photopolymerizable resin group containing a photopolymerizable compound and a photopolymerization initiator. The product is formed into a film on one side of the conductive particle-containing layer having a plurality of conductive particles, thereby forming an insulating resin layer.

In addition, the present invention provides a manufacturing method, which is the above-mentioned method for manufacturing an anisotropic conductive film, and has the following steps A to C: (step A) placing conductive particles into a recessed portion of a transfer mold having a plurality of recessed portions; Step; (Step B) a step of pressing a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator to conductive particles in a transfer mold, thereby forming a conductive particle-containing layer on which conductive particles are transferred ; And (Step C) forming an insulating resin by forming a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator on a conductive particle transfer surface of a conductive particle-containing layer to which conductive particles are transferred, thereby forming an insulating resin Layer of steps.

Further, the present invention provides a manufacturing method, which is the above-mentioned method for manufacturing an anisotropic conductive film, and has the following steps A, B, CC, and D: (step A) placing conductive particles into a transfer formed with a plurality of recesses Step of concave portion of mold; (Step B) Pressing a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator onto conductive particles in a transfer mold, thereby forming a conductive material containing conductive particles transferred thereto Steps of the particle layer; (Step CC) A step of forming an insulating resin layer by forming a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator on a non-transferable surface of a conductive particle containing a conductive particle layer on which conductive particles are transferred; and (Step D) A step of forming an adhesive layer on the surface on the opposite side of the insulating resin layer side including the conductive particle layer.

In addition, the present invention provides a connection structure in which the first electronic component is anisotropically conductively connected to the second electronic component using the anisotropic conductive film.

Regarding the anisotropic conductive film of the present invention having a structure in which an insulating resin layer is laminated and a conductive particle-containing layer in which a plurality of conductive particles are present, the insulating resin layer and the conductive particle-containing layer each contain a photopolymerizable compound and photopolymerization A layer of a photopolymerizable resin composition before polymerization of the initiator. Therefore, anisotropic conductive connection can be achieved with a single light irradiation even without performing photo-hardening treatment. Furthermore, the conductive particles exist independently of each other when the anisotropic conductive film is viewed from the top. That is, there are no aggregates of conductive particles. Therefore, when the anisotropic conductive film of the present invention is applied to an anisotropic conductive connection, the light incident on the insulating resin layer through the conductive particle-containing layer composed of the photopolymerizable resin composition is conducted by each of the conductive layers. Particles are blocked, but since the light between the conductive particles is diffused, as a result, the photopolymerization of the anisotropic conductive film (especially the insulating resin layer) can be made uniform, and good particle capture can be ensured. As a result, the target connection strength can be ensured, and the reduction in connection reliability can be further prevented. In addition, the anisotropic conductive film of the present invention has a transmittance in the thickness direction of light with a wavelength of 300 to 400 nm of more than 40%, so that the photopolymerization of the anisotropic conductive film (especially the insulating resin layer) can be more uniform. It can ensure good connection strength, and further prevent the reduction of connection reliability.

1. 51‧‧‧ insulating resin layer

2.52‧‧‧insulating adhesive

3.53‧‧‧Conductive particles

4, 54‧‧‧ layer containing conductive particles

5‧‧‧ Adhesive layer

10, 20, 30, 40, 50‧‧‧ anisotropic conductive film

FIG. 1 is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 2 is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 3 is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 4 is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 5 is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 6 is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 7 is a cross-sectional view of a conventional anisotropic conductive film.

Hereinafter, an example of the anisotropic conductive film of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same symbol represents the same or equivalent component.

<< Overall composition of anisotropic conductive film >>

FIG. 1 is a cross-sectional view of an anisotropic conductive film 10 according to an embodiment of the present invention. This anisotropic conductive film 10 has a structure in which an insulating resin layer 1 is laminated and a conductive particle-containing layer 4 in which a plurality of conductive particles 3 are present in an insulating adhesive 2.

In the present invention, the insulating resin layer 1 and the conductive particle-containing layer 4 are layers of a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator, respectively. In other words, it means that the insulating resin layer 1 and the conductive particle-containing layer 4 are in a state capable of photopolymerization. As long as it is in a state where photopolymerization is possible, anisotropic conductive connection can be achieved with a single light irradiation without performing a photo-hardening treatment.

In the anisotropic conductive film 10 of the present invention, the conductive particles 3 exist independently of each other when the anisotropic conductive film 10 is viewed from the top. Therefore, when the anisotropic conductive film 10 is irradiated with light from the conductive particle-containing layer 4 side, the entire insulating resin layer 1 can be photopolymerized well. Here, the "existence independently of each other" means a state in which the electric particles 3 are not in contact with each other without agglomeration, and do not overlap in the film thickness direction. Regarding the degree of "non-contact", the distance between centers of adjacent conductive particles 3 is preferably 1.5 to 50 times the average particle diameter, and more preferably 2 to 30 times. In addition, the "state which does not overlap in the film thickness direction" means that the conductive particles do not overlap with other conductive particles when the anisotropic conductive film is viewed in plan.

In addition, the ratio of "the conductive particles that exist independently" to all conductive particles is preferably 95% or more, more preferably 96% or more, and even more preferably 99% or more. This ratio can be obtained by observing an image of a specific area (for example, observing a plurality of areas of 100 μm × 200 μm, and the total area is at least 1 mm ² or more, and preferably 3 mm ² or more). The determination can be performed by an image analysis and measurement system (WinROOF, Mitani Corporation).

As described above, the conductive particles 3 exist independently of each other when the anisotropic conductive film 10 is viewed from the top, but in order to achieve uniform light transmission throughout the anisotropic conductive film 10, it is preferable to arrange them regularly. Examples of the regular arrangement include a hexagonal lattice, an oblique lattice, a square lattice, a rectangular lattice, and a parallel lattice. Moreover, it is not necessary to have a grid shape, but to form a line shape arranged in a line side by side. In this case, it is preferable that the lines exist in such a manner that the film is skewed in the width direction of the film. There is no particular limitation on the distance between the lines, and there may be rules or rules. In practice, it is better to have regularity.

In addition, the anisotropic conductive film 10 of the present invention has a wavelength including i rays. The film thickness direction transmittance of light at 300 to 400 nm is 40% or more, and preferably 60% or more. Therefore, the photopolymerization of the anisotropic conductive film (especially the insulating resin layer) can be made more uniform, a good connection strength can be ensured, and a decrease in connection reliability can be further prevented. Here, the film thickness when measuring the transmittance is usually 1 to 100 μm, and preferably 1 to 40 μm. The transmittance can be measured with a known spectrophotometer.

In the state of FIG. 1, a part of the conductive particles 3 protrudes from the conductive particle-containing layer 4 to the insulating resin layer 1. In other words, the conductive particles 3 exist at the interface between the insulating resin layer 1 and the conductive particle-containing layer 4. According to this aspect, the influence of light irradiation caused by the conductive particles on each layer can be minimized, and it becomes easy to blend the anisotropic conductive film or various physical properties, the reactivity of the curing agent, the life of the product, and the layer thickness. And other design factors.

<Insulating resin layer 1>

The insulating resin layer 1 is a layer of a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator. In order that polymerization can be performed even by heat pressure during anisotropic conductive connection, a thermal polymerization initiator is preferably contained. Examples of the photopolymerizable resin composition include a photoradically polymerizable acrylate-based composition containing a (meth) acrylate compound and a photoradical polymerization initiator, and an epoxy compound and a photocationic polymerization initiation. Photocationically polymerizable epoxy resin composition and the like. As described above, when a photo radical polymerization initiator is used, a thermal radical polymerization initiator may be used in combination. Similarly, when using a photocationic polymerization initiator, a thermal cationic polymerization initiator may be used in combination.

Here, as the (meth) acrylate compound, a conventionally known photopolymerizable (meth) acrylate monomer can be used. For example, a monofunctional (meth) acrylate-based monomer or a difunctional or more multifunctional (meth) acrylate-based monomer can be used. In the present invention, in order to be anisotropic conductive The insulating resin layer is thermally cured at the time of connection, and a polyfunctional (meth) acrylate monomer is preferably used for at least a part of the (meth) acrylate monomer. Here, (meth) acrylate includes acrylate and methacrylate.

Examples of the photo-radical polymerization initiator include well-known polymerization initiators such as acetophenone-based photopolymerization initiators, benzophenone ketal-based photopolymerization initiators, and phosphorus-based photopolymerization initiators.

In order to sufficiently advance the polymerization and suppress the decrease in rigidity, the amount of the photo-radical polymerization initiator used is preferably 0.1 to 25 parts by mass, and more preferably 0.5 to 15 parts relative to 100 parts by mass of the (meth) acrylate compound. Parts by mass.

Examples of the thermal radical polymerization initiator used in combination with the photo radical polymerization initiator include organic peroxides and azo compounds. In particular, it is preferable to use an organic peroxide that does not generate nitrogen that causes bubbles.

In order to suppress poor curing and reduce product life, the amount of the thermal radical polymerization initiator used is preferably 2 to 60 parts by mass and more preferably 5 to 100 parts by mass of the (meth) acrylate compound. 40 parts by mass.

Examples of the epoxy compound include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a novolac type epoxy resin, a modified epoxy resin thereof, an alicyclic epoxy resin, and the like, and these can be used in combination. Wait for more than 2 kinds. An oxycyclobutane compound may be used in addition to the epoxy compound.

As a photocationic polymerization initiator, a well-known photocationic polymerization initiator of an epoxy compound can be used, For example, a sulfonium salt, an onium salt, etc. are mentioned.

If the content of the photocationic polymerization initiator is too small, the reactivity disappears. If it is too much, the product life of the adhesive tends to decrease. Therefore, it is preferably 3 to 15 parts by mass and more preferably 5 to 10 parts by mass relative to 100 parts by mass of the epoxy compound.

As the thermal cationic polymerization initiator used in combination with the photocationic polymerization initiator, a known one can be used as the thermal cationic polymerization initiator of the epoxy compound. For example, a sulfonium salt, a sulfonium salt, and a sulfonium which can generate an acid upon heating As the salt, ferrocene, etc., an aromatic sulfonium salt exhibiting a good potential for temperature can be particularly preferably used.

If the blending amount of the thermal cationic polymerization initiator is too small, it tends to become poor in hardening; if it is too large, the product life tends to decrease. Therefore, it is preferably 2 to 60 parts by mass relative to 100 parts by mass of the epoxy compound. , More preferably 5 to 40 parts by mass.

The photopolymerizable resin composition preferably contains a film-forming resin or a silane coupling agent. Examples of the film-forming resin include phenoxy resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, and polyimide A resin, a polyolefin resin, or the like may be used in combination of two or more of them. Among these, a phenoxy resin can be preferably used from a viewpoint of film-forming property, processability, and connection reliability. Examples of the silane coupling agent include epoxy-based silane coupling agents and acrylic silane-based coupling agents. These silane coupling agents are mainly alkoxysilane derivatives.

Furthermore, fillers, softeners, accelerators, anti-aging agents, colorants (pigments, dyes), organic solvents, ion trapping agents, and the like may be blended in the photopolymerizable resin composition as necessary.

The thickness of the insulating resin layer 1 composed of the photopolymerizable resin composition as described above is preferably 3 to 50 μm, and more preferably 5 to 20 μm.

<Conductive particle-containing layer 4>

The conductive particle-containing layer 4 has a structure in which conductive particles are held by an insulating adhesive 2, and is preferably The insulating adhesive 2 includes a plurality of conductive particles 3. This insulating adhesive 2 is contained in the photopolymerizable compound and the photopolymerization initiator described in the insulating resin layer 1. Therefore, the conductive particle-containing layer 4 has a structure in which conductive particles 3 are present in a layer of a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator.

(Conductive particles 3)

The conductive particles 3 can be appropriately selected and used from among users of previously known anisotropic conductive films. Examples include metal particles such as nickel, cobalt, silver, copper, gold, palladium, alloy particles such as solder, and metal-coated resin particles. Two or more types may be used in combination.

The average particle diameter of the conductive particles 3 is preferably 2.5 μm or more and 30 μm or less, and more preferably 3 μm or more and 9 μm or less in order to cope with variations in wiring height and to suppress an increase in on-resistance and to suppress occurrence of a short circuit. The particle diameter of the conductive particles 3 can be measured with a general particle size distribution measurement device, and the average particle diameter can also be obtained using a commercially available particle size distribution measurement device (for example, FPIA-3000, manufactured by Malvern Instruments).

Furthermore, in the case where the conductive particles are metal-coated resin particles, in order to obtain good connection reliability, the particle hardness (20% K value; compression elastic deformation characteristic K ₂₀ ) of the resin core particles is preferably 100 to 1000 kgf / mm. ² , more preferably 200 to 500 kgf / mm ² . The compressive elastic deformation characteristics of the K ₂₀ series can be measured, for example, using a micro compression tester (MCT-W201, Shimadzu Corporation) at a measurement temperature of 20 ° C.

In order to suppress the reduction in the capture efficiency of the conductive particles and the occurrence of a short circuit, the amount of the conductive particles 3 in the anisotropic conductive film 10 is preferably 50 or more and 100,000 or less per 1 mm ² , more preferably 200 or more and 70,000 or more. Or less. The measurement of this amount can be performed by observing the film surface with an optical microscope. Moreover, before the anisotropic conductive connection, the conductive particles 3 in the anisotropic conductive film 10 may be difficult to observe with an optical microscope because the conductive particles 3 are present in the insulating adhesive 2. In this case, the anisotropic conductive film after the anisotropic conductive connection can also be observed. In this case, the existing amount can be calculated by considering the film thickness change before and after connection.

In order not to hinder light irradiation, the area occupancy of the conductive particles is preferably 70% or less, and more preferably 50% or less. In addition, in order to prevent a decrease in the number of captures to the terminals and to suppress an increase in the on-resistance value, it is preferably 5% or more, and more preferably 10% or more. Here, when the area occupancy ratio of the conductive particles is a plan view of the anisotropic conductive film, the ratio of the conductive particle area to the film area when the conductive particles are projected two-dimensionally on the film plane can be calculated by ordinary image analysis. .

In addition, when the conductive particles are regularly arranged with reference to the terminal layout, in order to suppress the reduction in the number of captured terminals to a minimum, if the area occupancy rate is 0.2% or more, there is no problem in actual use. In order to obtain a stable connection, it is preferably 5% or more, and more preferably 10% or more. The so-called regular arrangement of the layout of the reference terminals refers to an arrangement in which, for example, the longitudinal direction of a rectangular terminal (usually the width of the film in the case of a COG connection using an IC), the wiring other than the conductive particles does not fall on a straight line. In addition, it is a grid-like arrangement in which the outer wires penetrate the conductive particles. It can also be called a meandering state. Thereby, in the case where, for example, the conductive particles are present at the edge end portion of the terminal which is relatively difficult to be captured, the minimum conductive particles can be captured. In the case where the wires other than the conductive particles fall on a straight line (that is, the case where they are consistent), the conductive particles existing at the edge of the terminal may also become uncaptured. The above is an example of a configuration for avoiding this situation. Furthermore, in order to avoid a short circuit, the lower limit of the area occupancy is usually preferably less than 50%, more preferably less than 40%, and even more preferably 35% or less.

The amount of conductive particles 3 present in the anisotropic conductive film 10 can also be expressed on a mass basis. In this case, the amount of the anisotropic conductive film 10 is as follows: When the total mass is 100 parts by mass, it is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 10 parts by mass or less in the 100 parts by mass.

The thickness of the conductive particle-containing layer 4 is preferably 3 to 50 μm, more preferably 5 to 20 μm, but it is preferably not thicker than the insulating resin layer 1.

<Anisotropic Conductive Film in the State of Figure 2>

FIG. 2 is a cross-sectional view of an anisotropic conductive film 20 in a state different from that of FIG. 1. The anisotropic conductive film 20 in this aspect has a structure in which the entire conductive particles 3 are embedded in the conductive particle-containing layer 4. In this case, the shortest distance h from the interface between the insulating resin layer 1 and the conductive particle-containing layer 4 to each conductive particle 3 is preferably 3% or more of the average particle diameter of the conductive particles 3, and more preferably for all conductive particles. The particles are all approximately the same. As a result, since the conductive particles 3 are closer to the light irradiation side, the insulating resin layer 1 can be more uniformly photopolymerized. This is because the effect of the light source on each layer can be easily controlled by bringing the conductive particles serving as a shield of light closer to the light source side. In addition, if the upper limit of the shortest distance h is too large, the conductive particles are too close to the outer interface of the film, which may affect the viscosity of the film. Therefore, it is preferable that the closest distance of the conductive particles is 2 to 10% away from the outer interface of the film. about. The shortest distance h is substantially the same for all the conductive particles. This means that when the anisotropic conductive film is viewed in a cross section, the heights of the conductive particles are substantially the same.

(Relationship between the melt viscosity of the insulating resin layer 1 and the conductive particle-containing layer 4)

Considering the particle trapping property during anisotropic conductive connection of an anisotropic conductive film, it is preferable to have a relationship of “insulating resin layer <conducting particle-containing layer” regarding the melt viscosity. Specifically, the melt viscosity is based on the relationship of “insulating resin layer <conducting particle-containing layer”, and the melt viscosity of insulating resin layer 1 is preferably 3000 Pa at 80 ° C. Below s, more preferably 1000Pa. s or less; The melt viscosity of the conductive particle-containing layer is preferably 1000 to 60,000 Pa at 80 ° C. s, more preferably 3000 ~ 50000Pa. s. The melt viscosity of the whole film layer is preferably 100 ~ 10000Pa at 80 ° C. s, more preferably 500 ~ 5000Pa. s, more preferably 1000 ~ 3000Pa. s. The melt viscosity can be measured, for example, using a rotary rheometer (TA Instruments) at a temperature rise rate of 10 ° C./min, a measurement pressure of 5 g, and a measurement plate diameter of 8 mm.

<Anisotropic Conductive Film in the State of Figure 3>

FIG. 3 is a cross-sectional view of the anisotropic conductive film 30 in the modified form of the anisotropic conductive film 10 shown in FIG. 1 and is formed on the surface on the opposite side of the insulating resin layer 1 side including the conductive particle layer 4. There is the appearance of the adhesive layer 5. According to this aspect, even when the adhesiveness of the conductive particle-containing layer 4 is insufficient, it is possible to impart good adhesiveness to the anisotropic conductive film 30. Such an adhesive layer 5 can also be preferably applied to the anisotropic conductive film 20 (not shown) as shown in FIG. 2.

Such an adhesive layer 5 may be composed of a layer having the same composition as the photopolymerizable resin composition constituting the insulating resin layer 1 or the conductive particle-containing layer 4.

The thickness of the adhesive layer 5 is preferably 1 to 50 μm, and more preferably 1 to 20 μm. It is preferable that the total of the thicknesses of the adhesive layer 5 and the conductive particle-containing layer 4 is 1 to 10 times the relationship of the insulating resin layer 1.

(Relationship between the melt viscosity of the insulating resin layer 1, the conductive particle-containing layer 4, and the adhesive layer 5)

Considering the particle trapping property during anisotropic conductive connection of an anisotropic conductive film, it is preferable to have a relationship of "insulating resin layer <conducting particle-containing layer <adhesive layer" regarding the melt viscosity. Specifically, the melting viscosity is based on the premise of the relationship of "insulating resin layer <conducting particle-containing layer <adhesive layer", and the melting viscosity of the insulating resin layer 1 is preferably 3000 Pa at 80 ° C. Below s, more preferably 1000Pa. Below s; the melt viscosity of the layer containing conductive particles is preferably 1000 ~ 60000 at 80 ° C Pa. s, more preferably 3000 ~ 50,00000Pa. s; The melt viscosity of the adhesive layer is preferably 1000 to 40,000 Pa at 80 ° C. s, more preferably 3000 ~ 30000Pa. s. The melt viscosity of the whole film layer is preferably 100 ~ 10000Pa at 80 ℃. s, more preferably 500 ~ 5000Pa. s, more preferably 1000 ~ 3000Pa. s. The melt viscosity can be measured, for example, using a rotary rheometer (TA Instruments) under conditions of a temperature rise rate of 10 ° C./min, a measurement pressure of 5 g, and a measurement plate diameter of 8 mm.

<Anisotropic Conductive Film in the State of Figure 4>

The anisotropic conductive film 40 of FIG. 4 is a modified example of the anisotropic conductive film 30 of FIG. 3, and a part of the conductive particles 3 protrudes to the adhesive layer 5 side instead of the insulating resin layer 1 side. With such a configuration, the conductive particles 3 are arranged on the light irradiation side during anisotropic conductive connection, and more uniform and complete photopolymerization can be achieved in the entire anisotropic conductive film 40.

The conductive particles 3 preferably exist at the interface between the insulating resin layer 1 and the conductive particle-containing layer 4 as shown in FIG. 1 or FIG. 3 described above, or exist in the adhesive layer 5 and the conductive particle-containing layer 4 as shown in FIG. 4. The interface between the layers is present on the conductive particle-containing layer 4 side near the interface between the insulating resin layer 1 and the conductive particle-containing layer 4 as shown in FIG. 2. Regarding the aspect of FIG. 2, although the shortest distance h from the interface between the insulating resin layer 1 and the conductive particle-containing layer 4 to each of the conductive particles 3 has been described, for these aspects, it is also possible to focus on the insulation property. The interface between the resin layer 1 and the conductive particle-containing layer 4 will be described below from the viewpoint of the "reference line" and the "center point" of the conductive particles.

(Distance from the reference line to the center point of the conductive particles)

That is, when the cross section of the anisotropic conductive film is observed, the interface between the insulating resin layer 1 and the conductive particle-containing layer 4 is used as a reference line, and the direction of the conductive particle-containing layer 4 side is taken as a reference line. When it is set to be positive, the distance from the reference line to the center point of the conductive particles is preferably -80% or more of the diameter of the conductive particles, and more preferably -75% or more from the viewpoint of ease of production. From the viewpoint of stabilizing the catchability at the time of connection, it is preferably 80% or less, and more preferably 75% or less. By embedding the conductive particles in the conductive particle-containing layer 4 in this manner, the flow of the conductive particles is suppressed in the conductive particle-containing layer 4 which is not obstructed by the conductive particles when light is irradiated, and the capture property of the conductive particles can be improved. In addition, since the hardening of the insulating resin layer 1 also becomes uniform, it is also possible to avoid a decrease in connection reliability. In other words, since the conductive particles exist at the interface between the conductive particle-containing layer 4 and other resin layers having different characteristics such as melt viscosity, the flow of the conductive particles itself can be suppressed without impeding the pressing of the conductive particles. The reason is that the pressing direction of the conductive particles is the thickness direction of the layer, and the direction of the resin flow is mainly a direction aligned with this. However, for good reproducibility and appropriately adjusting the forces acting in these different directions, The conductive particles are also preferably present between the membrane interfaces. When the center points of the conductive particles are not exactly the same, the average value is set as the center point.

When the position in the film thickness direction of the conductive particles is near the outer interface of the film, the distance from the outer interface of the film to the center point of the conductive particles is preferably smaller than the distance between the particles when the conductive particles are viewed in plan. Thereby, even if light is incident from the outer interface side, the influence of shielding the incident light by the conductive particles can be suppressed to a minimum.

<Manufacturing method of anisotropic conductive film>

The anisotropic conductive film of the present invention can be produced by a conductive particle-containing layer having a plurality of conductive particles held in an insulating adhesive (for example, a conductive particle-containing layer having a plurality of conductive particles in an insulating adhesive). ) On one side, a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator is formed into a film to form an insulating resin layer, and an adhesive layer is formed on the surface of the conductive particle-containing layer as necessary. Here, the conductive particles containing a plurality of conductive particles are held in the insulating adhesive. The sublayer (for example, a conductive particle-containing layer having a plurality of conductive particles in an insulating adhesive) can be used to spread the conductive particles on the surface of the insulating film by using a conventionally known method, or by attaching them in a single layer It is formed by extending it biaxially. It can be formed even by using a transfer mold. Furthermore, in these cases, the conductive particles may be pressed into the insulating adhesive, and the influence caused by the pressing may be caused by the insulating adhesive around the outer periphery of the conductive particles. Low temperature and low pressure to the extent that anisotropic conductive film can adversely affect). For example, as shown in FIG. 5, the slope 2 a is formed so as to follow the outer periphery of the conductive particles 3. Alternatively, as shown in FIG. 6, the surface of the insulating adhesive 2 directly above the conductive particles 3 embedded without being exposed from the insulating adhesive 2 forms undulations 2b. Here, the inclination 2a refers to an inclined surface in which the insulating adhesive 2 is deeply formed due to the embedding of the conductive particles 3, and the inclined surface includes a vertical surface or an overhang surface. In addition, the undulation 2b refers to a product obtained by depositing a small amount of the insulating adhesive 2 on the conductive particles after the formation of inclination, depending on the degree of indentation or conditions described above (the inclination may disappear due to the accumulation). Such an inclination 2a or an undulation 2b exists along the outer periphery of the conductive particles, and therefore, it can be easily confirmed by comparing with the surface state of the insulating adhesive 2 between the conductive particles. In this way, by forming an inclination or undulation in the insulating adhesive, a part or the whole of the conductive particles are embedded and held in the insulating adhesive, so that the influence of resin flow and the like during connection can be minimized. Capturing of conductive particles is improved. Furthermore, if the tilt or undulation exists along the outer periphery of the conductive particles 3, an insulating adhesive constituting a conductive particle-containing layer having a relatively high viscosity is more likely to be held on one side of a pair of terminals holding the conductive particles. There is a small amount on one side, and therefore, it is expected that when an anisotropic conductive connection is made, the pressing force from the terminal can be easily applied to the conductive particles. In addition, if there is undulation, the amount of resin directly above the conductive particles is smaller than the surrounding area, so the following effect can be expected: In anisotropic conductive connection, it is easy to exclude the insulating adhesive directly above the conductive particles, the terminals and the The conductive particles become easy to contact; the capturing property of the conductive particles on the terminal is improved, and the conduction reliability is improved. It is speculated that these effects associated with undulations are more likely to appear with tilt. In addition, although an example of manufacturing using a transfer mold is described below, the conditions for forming a slope or undulation in the conductive particle-containing layer are not limited to the manufacturing conditions listed in the following manufacturing examples.

The anisotropic conductive films 10 and 30 shown in FIGS. 1 and 3 can be manufactured according to the following steps A to C.

First, the conductive particles are placed in a concave portion of a transfer mold in which a plurality of concave portions are formed (step A). Then, a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator is pressed against the conductive particles in the transfer mold, thereby forming a conductive particle-containing layer on which conductive particles are transferred (step B). Furthermore, on the conductive particle transfer surface on which the conductive particle layer containing the conductive particles is transferred, a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator is formed into a film, thereby forming an insulating resin layer (step C). Thereby, an anisotropic conductive film can be obtained. In addition, as for the insulating resin layer composed of a photopolymerizable resin composition, its minimum melt viscosity can be set to 2000 Pa. above s (preferably 3000 ~ 15000Pa.s), the viscosity at 60 ° C is set to 3000Pa. above s (preferably above 3000 ~ 20,000 Pa.s). In addition, as a condition at the time of pressing in step B, a condition of pressing at a temperature of 60 ° C. to 70 ° C. and 0.5 MPa can be exemplified, but it is not limited to this condition.

Furthermore, it is preferable to separate the conductive particle-containing layer from the transfer mold after step B and before step C. In addition, by adjusting the pressing in step B, the embedding degree of the conductive particles in the conductive particle-containing layer can be changed. By increasing the pressing degree, the embedding degree of the conductive particles in the conductive particle-containing layer will be increased, and finally it can be completely embedded in the conductive particle-containing layer.

In addition, the anisotropic conductive film 20 in the state shown in FIG. 2 can be obtained after step C. An adhesive layer is formed on the surface opposite to the insulating resin layer side of the conductive particle-containing layer (step D), and is manufactured.

The anisotropic conductive film 40 shown in FIG. 4 can be manufactured according to the following steps A, B, CC, and D.

First, the conductive particles are placed in a concave portion of a transfer mold in which a plurality of concave portions are formed (step A). Then, a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator is pressed against the conductive particles in the transfer mold, thereby forming a conductive particle-containing layer on which conductive particles are transferred (step B). Furthermore, a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator is formed on a non-transferable surface of a conductive particle containing a conductive particle layer to which conductive particles are transferred, thereby forming an insulating resin layer (step CC). Further, an adhesive layer is formed on the conductive particle transfer surface of the conductive particle-containing layer (step D). Thereby, an anisotropic conductive film can be obtained.

Furthermore, it is preferable to separate the conductive particle-containing layer from the transfer mold after step CC and before step D.

(Transfer mold)

As the transfer mold used in the manufacturing method of the present invention, for example, a well-known opening forming method such as photolithography can be used, and inorganic materials such as silicon, various ceramics, glass, and stainless steel, or organic materials such as various resins can be used. Materials and the like are formed by openings. The transfer mold may have a shape such as a plate shape or a roll shape.

Examples of the shape of the concave portion of the transfer mold include a cylindrical shape, a column shape such as a quadrangular pillar, a conical shape, a pyramid shape, a conical shape, and a pyramid shape such as a quadrangular pyramid.

As the arrangement of the recesses, a lattice shape, a zigzag shape, or the like can be used in accordance with the arrangement used for the conductive particles.

In terms of the balance between the improvement of transferability and the retention of conductive particles, the ratio of the average particle diameter of the conductive particles to the depth of the recesses (= the average particle diameter of the conductive particles / the depth of the openings) is preferably 0.4 to 3.0, more preferably It is 0.5 ~ 1.5. The diameter and depth of the concave portion of the transfer mold can be measured with a laser microscope.

In terms of the balance between the ease of accommodating the conductive particles and the ease of press-fitting of the insulating resin, the ratio of the opening diameter of the recessed portion to the average particle diameter of the conductive particles (= opening diameter of the recessed portion / average particle diameter of the conductive particles) ) Is preferably 1.1 to 2.0, and more preferably 1.3 to 1.8.

When the bottom diameter of the recess is smaller than the opening diameter, it is preferable to set the bottom diameter to be 1.1 times or more and not more than 2 times the conductive particle diameter, and set the opening diameter to be 1.3 times or more the conductive particle diameter. Up to 3 times.

<< connection structure >>

The anisotropic conductive film of the present invention can be preferably applied when anisotropically conductively connects a first electronic component such as an IC chip, an IC module, and an FPC to a second electronic component such as a plastic substrate or a glass substrate. As long as energy rays (such as ultraviolet rays) can pass through any electronic component without impairing the effect of the present invention, various materials can be used as the material of these electronic components. The connection structure obtained in this way is also a part of the present invention.

As a method of connecting an electronic part using an anisotropic conductive film, for example, it can be manufactured by the following method: self-contained conductive particle layer side, or when an anisotropic conductive film is formed on the self-adhesive layer side when an adhesive layer is formed To various electronic components such as various substrates; and to mount the first electronic component such as IC chip and FPC on the anisotropic conductive film after being temporarily pasted, while pressing from the first electronic component side with a hot press tool, The second electronic component is irradiated with light. The timing of light irradiation or the timing of start and end can be adjusted appropriately. It can also be manufactured as follows: self-contained conductive particles The anisotropic conductive film is temporarily attached to the second electronic component from the side of the sub-layer, or from the side of the adhesive layer in the case where an adhesive layer is formed; The electronic component is pressed from the first electronic component side by a hot press tool. In this case, light irradiation may be performed from the second electronic component side in the same manner as described above.

[Example]

Hereinafter, the present invention will be specifically described by way of examples. The melt viscosity was measured using a rotary rheometer (TA Instruments) under the conditions of a temperature rise rate of 10 ° C / min, a measurement pressure of 5 g, a measurement plate diameter of 8 mm, and a measurement temperature of 80 ° C. The light transmittance was measured using a spectrophotometer (UV-3600, Shimadzu Corporation) at a wavelength of 300 to 400 nm. The ratio of independent conductive particles to all conductive particles (independent particle ratio), or area ratio of conductive particles was measured using WinROOF of Mitani Corporation. Furthermore, the distance between the position of the center point of the conductive particles and the interface (reference line) between the insulating resin layer and the conductive particle-containing layer was measured based on observation with a metal microscope.

In addition, Table 1 shows each of the blending points of the insulating resin layer, the conductive particle-containing layer, and the adhesive layer applied to the following Examples 1 to 16 and Comparative Examples 1 to 4 in advance.

Example 1 (manufacturing of anisotropic conductive film of Fig. 1)

(Formation of insulating resin layer)

As shown in Table 1, 50 parts by mass of a phenoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd., YP-50), 30 parts by mass of a liquid epoxy resin (Mitsubishi Chemical Co., Ltd., jER828), and a photocation were prepared. 4 parts by mass of a polymerization initiator (BASF Japan Co., Ltd., Irgacure 250), 4 parts by mass of a thermal cationic polymerization initiator (Sanxin Chemical Industry Co., Ltd., SI-60L), silicon dioxide filler (airoxel R805, Japan Elosir Co., Ltd.) 20 parts by mass and a silane coupling agent (Shin-Etsu Chemical Industry Co., Ltd., KBM-403) 1 part by mass of a photopolymerizable resin composition, which was applied to a film thickness of 50 μm The PET film was dried in an oven at 80 ° C. for 5 minutes, and the thickness of the thickness (14 μm) of Table 2 was formed on the PET film. Insulating resin layer. Table 2 shows the melt viscosity of this insulating resin layer. Furthermore, in this example and the following examples and comparative examples, the measurement of the melt viscosity was performed using a rotary rheometer (TA Instruments) at a temperature rise rate of 10 ° C./min, the measurement pressure was fixed at 5 g, and the diameter of the measurement plate was used. It was performed under the condition of 8 mm, and the melt viscosity at 80 ° C was obtained.

(Formation of the layer containing conductive particles)

On the other hand, a mold having an array pattern of convex portions corresponding to a square lattice pattern was produced, and a pellet obtained by melting particles of a known transparent resin was flowed into the mold and cooled to solidify, thereby producing a sheet having Table 2 Resin transfer mold with a density (corresponding to the particle density of conductive particles) in the concave portion of the square lattice pattern. The concave portion of the transfer mold was filled with conductive particles (Sekisui Chemical Industry Co., Ltd., AUL703, particle diameter: 3 μm).

In addition, as shown in Table 1, 25 parts by mass of a phenoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd., YP-50), 30 parts by mass of a liquid epoxy resin (Mitsubishi Chemical Co., Ltd., jER828), 4 parts by mass of photocationic polymerization initiator (BASF Japan Co., Ltd., Irgacure 250)), 4 parts by mass of thermal cationic polymerization initiator (Sanxin Chemical Industry Co., Ltd., SI-60L), silicon dioxide filler (Ai Rossier R805, Japan Aerosil Corporation) 45 parts by mass and 1 part by mass of a photopolymerizable resin composition of a silane coupling agent (Shin-Etsu Chemical Industry Co., Ltd., KBM-403). The resin composition was coated on a PET film having a thickness of 50 μm, and dried in an oven at 80 ° C. for 5 minutes to obtain an adhesive resin film. The resin film was covered and pressed at a temperature of 50 ° C. and a pressure of 0.5 MPa when pressed. To the conductive particle receiving surface of the transfer mold, thereby transferring the conductive particles to the resin film, thereby forming a conductive particle-containing layer having a thickness (4 μm) as shown in Table 2. Next, the conductive particle-containing layer was peeled from the transfer mold. The melt viscosity of this conductive particle-containing layer and the independent conductive particles are compared with all the conductive particles The ratios and the ratios of the conductive particle occupied areas are shown in Table 2. The state and pattern of the conductive particles were observed under a microscope, and at least the entire area of the cut film (1.8 mm × 22 mm) used for connection was confirmed.

(Laminated layer containing conductive particles and insulating resin layer)

The insulating resin layer is opposed to the transfer surface of the conductive particles containing the conductive particle layer, and this is bonded under the conditions of a temperature of 50 ° C and a pressure of 0.2 MPa when pressed; ultraviolet rays with a wavelength of 365 nm and a cumulative light amount of 4000 mJ / cm ² Thereby, the anisotropic conductive film of FIG. 1 is manufactured. The transmittance of the obtained anisotropic conductive film to i-rays was measured and evaluated in accordance with the following evaluation criteria. The obtained results are shown in Table 2. Also, the position of the center point of the conductive particles with respect to the interface (reference line) between the insulating resin layer and the conductive particle-containing layer was measured using a metal microscope, and the result was 0.00 μm.

A (very good): Light transmittance above 60%

B (Good): The light transmittance is more than 50% and less than 60%

C (general): the light transmittance is more than 40% and less than 50%

D (bad): light transmittance is less than 40%

Examples 2 to 6 (manufacturing of anisotropic conductive film of Fig. 2)

When forming the conductive particle-containing layer, the shortest distances between the conductive particles and the interface between the insulating resin layer and the conductive particle-containing layer were 1.50 μm (Example 2), 1.75 μm (Example 3), and 2.00 μm (Example 4). An anisotropic conductive film was produced in the same manner as in Example 1 except that conductive particles were embedded in the conductive particle-containing layer in the manner of 2.25 μm (Example 5) and 2.50 μm (Example 6).

Embodiment 7 (manufacturing of an anisotropic conductive film of FIG. 3)

(Formation of insulating resin layer)

The same adhesive insulating resin layer as in Example 1 was formed.

(Formation of the layer containing conductive particles)

As shown in Table 1, 40 parts by mass of a phenoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd., YP-50) and 30 parts by mass of a liquid epoxy resin (Mitsubishi Chemical Co., Ltd., jER828) were photocationically polymerized. 4 parts by mass of an initiator (BASF Japan Co., Ltd., Irgacure 250), 4 parts by mass of a thermal cationic polymerization initiator (San Shin Chemical Industry Co., Ltd., SI-60L), silicon dioxide filler (Aerosil R805 , Japan Elosir Co., Ltd.) 30 parts by mass, and 1 part by mass of a silane coupling agent (Shin-Etsu Chemical Industry Co., Ltd., KBM-403) constitute a photopolymerizable resin composition, and will retain the resin film of conductive particles. A conductive particle-containing layer was formed in the same manner as in Example 1 except that the thickness was set to 2 μm. Table 2 shows the melt viscosity of the conductive particle-containing layer, the particle area occupancy of the conductive particles, and the ratio of the conductive particles that exist independently to all the conductive particles.

(Formation of adhesive layer)

In addition, the phenoxy resin (Nippon Steel & Sumitomo Chemical Co., Ltd., YP-50) was changed to 30 parts by mass, and the silica filler (Ilocicill R805, Japan's Ilocicil Corporation) was changed to 40. Except for mass parts, an adhesive layer was produced in the same manner as in the conductive particle-containing layer. The melt viscosity of this adhesive layer is shown in Table 2.

(Laminated layer containing conductive particle layer, insulating resin layer, and adhesive layer)

The insulating resin layer and the conductive particle transfer surface of the conductive particle-containing layer are opposed to each other. After thermocompression bonding, the laminate is removed from the transfer mold, and the temperature is 50 ° C and 0.2MPa when pressed. The adhesive layer is adhered to the non-transferable surface of the conductive particles containing the conductive particle layer, thereby manufacturing the anisotropic conductive film of FIG. 3. The evaluation of the transmittance of the obtained anisotropic conductive film to i-rays is shown in FIG. Table 2.

Examples 8 and 9 (manufacturing of anisotropic conductive film of Fig. 4)

When forming the conductive particle-containing layer, the conductive particles were embedded in the conductive particles such that the shortest distance between the conductive particles and the interface between the insulating resin layer and the conductive particle-containing layer was 1.50 μm (Example 8) and 2.50 μm (Example 9). An anisotropic conductive film was produced in the same manner as in Example 7 except for the conductive particle layer.

Examples 10 and 11 (manufacturing of anisotropic conductive film of Fig. 4)

The thickness of the adhesive layer is 1 μm, and the thickness of the conductive particle-containing layer is 3 μm. When the conductive particle-containing layer is formed, the shortest distance between the conductive particles and the interface between the insulating resin layer and the conductive particle-containing layer is 1.50 μm (implementation). Example 10) An anisotropic conductive film was produced in the same manner as in Example 7 except that the conductive particles were embedded in the conductive particle-containing layer in the manner of 2.50 μm (Example 11).

Examples 12 and 13 (manufacturing of anisotropic conductive film of Fig. 4)

The thickness of the adhesive layer is 0.5 μm, and the thickness of the conductive particle-containing layer is 3.5 μm. When the conductive particle-containing layer is formed, the shortest distance between the conductive particles and the interface between the insulating resin layer and the conductive particle-containing layer is 1.50 μm. (Example 12) An anisotropic conductive film was produced in the same manner as in Example 7 except that conductive particles were embedded in the conductive particle-containing layer in the manner of 2.50 μm (Example 13).

Examples 14 and 15 (manufacturing of anisotropic conductive film of Fig. 4)

The conductive particle density was set to 30 × 10 ³ particles / mm ² and the particle area occupation ratio was 21.2% (Example 14), or the conductive particle density was set to 15 × 10 ³ particles / mm ² and the particle area occupied An anisotropic conductive film was produced in the same manner as in Example 8 except that the ratio was set to 10.6% (Example 15).

Embodiment 16 (manufacturing of an anisotropic conductive film of FIG. 4)

In Example 16, a photocationic polymerization initiator (BASF Japan Co., Ltd., Irgacure 250) was not blended with each layer containing the conductive particle layer, the insulating resin layer, and the adhesive layer, and the ultraviolet irradiation was omitted during lamination. An anisotropic conductive film was produced in the same manner as in Example 14.

Comparative Examples 1 to 3 (manufacturing of anisotropic conductive film of Fig. 7)

(Formation of insulating resin layer)

The same adhesive insulating resin layer as in Example 1 was formed.

(Formation of the layer containing conductive particles)

For the photopolymerizable resin composition, 30 parts by mass of a phenoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd., YP-50), 30 parts by mass of a liquid epoxy resin (Mitsubishi Chemical Co., Ltd., jER828), and 4 parts by mass of a cationic polymerization initiator (BASF Japan Co., Ltd., Irgacure 250), 4 parts by mass of a thermal cationic polymerization initiator (Sanxin Chemical Industry Co., Ltd., SI-60L), silica filler (Irosic R805, Japan Aerosil Corporation) 40 parts by mass, 1 part by mass of a silane coupling agent (Shin-Etsu Chemical Industry Co., Ltd., KBM-403), and conductive particles (Sekisui Chemical Industry Co., Ltd., AUL703, particle size 3 μm) 60 parts by mass (Comparative Example 1), 30 parts by mass (Comparative Example 2), or 15 parts by mass (Comparative Example 3) were uniformly mixed to prepare a photopolymerizable resin composition containing conductive particles. This was coated on a PET film having a film thickness of 50 μm, and dried in an oven at 80 ° C. for 5 minutes to form an adhesive conductive particle-containing layer having a thickness of Table 2 on the PET film.

(Laminated layer containing conductive particles and insulating resin layer)

The insulating resin layer and the conductive particle-containing layer were opposed to each other, and the temperature was 50 ° C and the pressure was 0.2 during the pressing. These were bonded together under the condition of MPa to manufacture the anisotropic conductive film of FIG. 7.

Comparative Example 4

Comparative Example 4 A phenoxy resin (Nippon Steel & Sumitomo Chemical Co., Ltd., YP-50) containing a conductive particle layer was changed to 50 parts by mass, and a silica filler (Ilocicill R805, Ilocicill, Japan) Co., Ltd.), except that it was changed to 20 parts by mass, an anisotropic conductive film was produced in the same manner as in Example 7.

<Evaluation>

For the anisotropic conductive films of Examples 1 to 16 and Comparative Examples 1 to 4, the following evaluation ICs were anisotropically conductively connected to a glass substrate by UV irradiation connection or thermocompression connection under the following conditions, and produced for evaluation. Connection structure.

Evaluation IC: Outline = 1.8mm × 20mm × 0.2mm, gold bump specification = 15μm (height) × 15μm (width) × 100μm (length) (gap between bumps 15μm)

Glass substrate with TiAl coating wiring: outer diameter = 30mm × 50mm × 0.5mm

UV irradiation connection: thermal compression bonding at 100 ° C and 80 MPa for 5 seconds. On the other hand, after 4 seconds from the start of thermal compression bonding, irradiate from an ultraviolet irradiation device (Omron Corporation, ZUV-C30H) for 1 second. Bell i-ray.

Thermocompression bonding: The thermocompression bonding is performed from the IC chip side at 150 ° C (arriving temperature) and 80MPa for 5 seconds. The tool width is set to 1.8mm.

For these manufactured connection structures for evaluation, (a) initial on-resistance, (b) on-reliability, (c) short-circuit occurrence rate, (d) temporary adhesion, ( e) Particle trapping property, (f) Joint strength, (g) Hardening rate (photopolymerization rate) of the insulating resin layer, (h) Hardening rate (photopolymerization rate) of the entire anisotropic conductive film, (i) Wiring Space difference The hardening rate (photopolymerization rate) of the anisotropic conductive film and (j) the hardening rate (photopolymerization rate) of the anisotropic conductive film in the central portion of the wiring were evaluated. The obtained results are shown in Table 2.

(a) Initial on resistance

As for the on-resistance of the obtained connection structure for evaluation, a digital multimeter was used to measure the value at a current of 2 mA using a four-terminal method. In practical use, it is expected that the measured resistance value is 1 Ω or less.

(b) Continuity reliability

The obtained connection structure for evaluation was measured for the on-resistance after being left in a constant temperature bath at a temperature of 85 ° C. and a humidity of 85% RH for 500 hours in the same manner as the initial on-resistance. In practical use, it is expected that the measured resistance value is 5 Ω or less.

(c) Short circuit occurrence rate

A digital multimeter was used to measure the short-circuit occurrence rate of the obtained connection structure for evaluation. The short-circuit occurrence rate was calculated by dividing the number of short-circuit occurrences of the connection structure by the space number of 15 μm, and evaluated based on the following criteria.

(Evaluation criteria)

A (very good): when the short-circuit occurrence rate is less than 10 ppm

B (Good): When the short-circuit occurrence rate is 10 ppm or more and less than 50 ppm

C (general): when the short-circuit occurrence rate is 50 ppm or more and less than 200 ppm

D (bad): when the short-circuit occurrence rate is 200 ppm or more

(d) Provisional

Using a commercially available ACF attachment device (model TTO-1794M, Shibaura Mechatronics Co., Ltd.), an anisotropic conductive film was attached to a glass substrate in a size of 2 mm × 5 cm, and After 1 second, the temperature reached 40 ~ 80 ° C, temporarily apply the pressure at 1 MPa, and flip the glass substrate. In this case, visually check whether the anisotropic conductive film peels off or floats from the glass substrate, according to the following criteria Evaluate.

(Evaluation criteria)

A (very good): a case where it can be temporarily affixed even at 40 ° C

B (Good): Temporary paste at 40 ℃, but temporary paste at 60 ℃

C (general): Temporary paste at 60 ℃, but temporary paste at 80 ℃

D (bad): the case where it cannot be temporarily posted at 80 ° C

(e) Particle capture

The terminal after the connection was observed with a metal microscope from the glass substrate side, and the number of indentations was counted to determine the capture property of the particles. The determination criteria are shown below. Specifically, the number of indentations on bumps (bump size 15 μm × 100 μm) of an IC wafer with a connection area of 1500 μm ² was counted.

(Evaluation criteria)

A (very good): 10 or more

B (Good): 5 or more and less than 10

C (general): 3 or more but less than 5

D (bad): less than 3

(f) Joint strength

For the connection structure for evaluation, a probe of a wafer shear strength tester (4000 series, Nordson Advanced Technology Co., Ltd.) was pressed against the side of the IC wafer, and a shear was applied at a speed of 100 μm / sec in the plane direction of the glass substrate. Force to measure the bonding strength. to In actual use, a bonding strength of 20 MPa or more is expected.

(g) Hardening rate (photopolymerization rate) of the insulating resin layer

A single-component conductive particle-containing layer (or a multilayer body containing a conductive particle layer and an adhesive layer) is placed on a single-component insulating resin layer, from the conductive particle-containing layer (or a multilayer body containing a conductive particle layer and an adhesive layer) UV irradiation was performed, and thereafter, only the curing rate of the insulating resin layer was measured using an FT-IR device (IR _T- 100, Shimadzu Corporation) (the same applies to the following evaluation items (h) to (j)). In practical use, a hardening rate of 70% or more is expected.

(h) Hardening rate (photopolymerization rate) of the entire anisotropic conductive film

The hardening rate of the hardened | cured material of the anisotropic conductive film which remained on the glass substrate surface and IC wafer surface of the connection structure which was destroyed at the time of joint strength evaluation was measured. In actual use, a lower hardening rate is expected to be 70% or more.

(i) Hardening rate (photopolymerization rate) of anisotropic conductive film in wiring space

The hardening rate of the hardened | cured material of the anisotropic conductive film which remained in the inter-wiring space on the glass substrate surface of the connection structure which was destroyed at the time of joint strength evaluation was measured. In practical use, a hardening rate of 70% or more is expected.

(j) Hardening rate of the anisotropic conductive film in the center of the wiring

The hardening rate of the hardened | cured material of the anisotropic conductive film which remained in the center part of the wiring of the connection structure which destroyed the bonding strength evaluation on the glass substrate surface was measured. In practical use, a hardening rate of 70% or more is expected.

As can be seen from Table 2, the anisotropic conductive films of Examples 1 to 16 showed good results in any of the evaluation items. In particular, it can be seen from the results of Examples 1 to 6 and the results of Examples 7 and 8 that as the distance between the center points of the particles spaced from the interface becomes longer, the particle trapping property tends to be improved. The light transmittance evaluation tends to decrease, but it is possible to maintain a level without problems in actual use. Further, it is understood from the results of Examples 14 and 15 that as the particle density (particle area occupancy) increases, the particle trapping property is improved. Furthermore, regarding the anisotropic conductive films of Examples 1 to 16, the melt viscosity of the entire film at 80 ° C was 500 to 5000 Pa. The range of s. The measurement of the melt viscosity is performed by the same method as the above method.

In contrast, in the anisotropic conductive films of Comparative Examples 1 to 3, since the independent particle ratio of the conductive particles is less than 70%, the light transmittance to i-rays is reduced, and the insulating resin layer and the anisotropic conductive film are The overall hardening rate (photopolymerization rate) becomes insufficient, temporary adhesion and particle trapping properties decrease, and reduction in conduction reliability occurs.

In addition, it was found that in the anisotropic conductive film of Comparative Example 4, although the independent particle ratio of the conductive particles was 95% or more, the particle area occupancy ratio exceeded 70%, and the particle trapping property was reduced.

[Industrial availability]

The anisotropic conductive film of the present invention is useful for anisotropic conductive connection of electronic components such as IC wafers to a wiring substrate. The narrowing of the wiring of electronic parts is continuously promoted, and the present invention is particularly useful in the case of anisotropic conductive connection of narrowed electronic parts.

Claims (16)

An anisotropic conductive film is laminated with an insulating resin layer and a conductive particle-containing layer in which a plurality of conductive particles are present. The insulating resin layer and the conductive particle-containing layer are photopolymerizations containing a photopolymerizable compound and a photopolymerization initiator, respectively. In the layer of the anisotropic conductive composition, conductive particles exist independently of each other when viewed from the anisotropic conductive film. The anisotropic conductive film has a transmittance in the thickness direction of light having a wavelength of 300 to 400 nm of 40% or more. For example, the anisotropic conductive film according to item 1 of the patent application, in which conductive particles exist near the interface between the insulating resin layer and the layer containing the conductive particles, or near the interface between the insulating resin layer and the layer containing the conductive particles. The conductive particle-containing layer side. For example, in the anisotropic conductive film of the first patent application scope, when the interface between the insulating resin layer and the layer containing the conductive particle is set as a reference line and the direction of the side containing the conductive particle layer is set as a positive, At the baseline, the center point of the conductive particles exists in the range of -80% to 80% of the conductive particle size. For example, the anisotropic conductive film according to any one of the claims 1 to 3, wherein the melt viscosity has a relationship of "insulating resin layer <conductive particle-containing layer". For example, the anisotropic conductive film according to any one of claims 1 to 4, wherein, in the film thickness direction, the distance from the outer interface of the film on the side where the conductive particles exist to the center point of the conductive particles is smaller than when the conductive particles are viewed from the top. The distance between particles. For example, in the anisotropic conductive film according to any of claims 1 to 5, the adhesive layer is formed on the surface on the opposite side of the insulating resin layer side of the conductive particle-containing layer. For example, the anisotropic conductive film according to item 6 of the patent application scope has a relationship of "insulating resin layer <containing conductive particle layer <adhesive layer" regarding the melt viscosity. For example, the anisotropic conductive film according to any one of claims 1 to 7, wherein the photopolymerization initiator is a photocationic polymerization initiator. The anisotropic conductive film according to any one of claims 1 to 8, wherein the insulating resin layer further contains a thermal polymerization initiator. For example, the anisotropic conductive film according to item 9 of the application, wherein the thermal polymerization initiator is a thermal cationic polymerization initiator or a thermal radical polymerization initiator. For example, the anisotropic conductive film according to any one of claims 1 to 10, wherein the conductive particles are regularly arranged in a grid pattern. A method for manufacturing an anisotropic conductive film under the scope of patent application No. 1 is to form a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator into a film containing a plurality of conductive particles in a conductive state. One side of the particle layer forms an insulating resin layer. A method for manufacturing an anisotropic conductive film in the scope of patent application No. 1 has the following steps A to C: (step A) a step of placing conductive particles in a concave portion of a transfer mold having a plurality of concave portions; (step B) a step of pressing a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator onto conductive particles in a transfer mold, thereby forming a conductive particle-containing layer on which conductive particles are transferred; and (step C) A step of forming an insulating resin layer by forming a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator on a conductive particle transfer surface of a conductive particle-containing layer to which conductive particles are transferred. For example, the manufacturing method according to item 13 of the patent application further includes the following step D: (step D) a step of forming an adhesive layer on the surface on the opposite side of the insulating resin layer side of the conductive particle layer. A method for manufacturing an anisotropic conductive film in the scope of patent application No. 1 has the following steps A, B, CC, and D: (step A) placing conductive particles in a recess of a transfer mold having a plurality of recesses Step; (Step B) a step of pressing a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator to conductive particles in a transfer mold, thereby forming a conductive particle-containing layer on which conductive particles are transferred (Step CC) forming an insulating resin by forming a photopolymerizable resin composition containing a photopolymerizable compound and a photopolymerization initiator on a non-transferable surface of a conductive particle containing a conductive particle layer on which conductive particles are transferred, thereby forming an insulating resin A step of forming a layer; and (step D) a step of forming an adhesive layer on a surface on the opposite side of the insulating resin layer side of the conductive particle-containing layer. A connection structure is an anisotropic conductive connection of a first electronic component to a second electronic component by using an anisotropic conductive film according to any one of claims 1 to 11.