CN113053562A - Insulating coated conductive particle, anisotropic conductive film and method for producing same, connection structure and method for producing same - Google Patents

Abstract

The invention provides an insulating coated conductive particle, an anisotropic conductive film and a method for manufacturing the same, a connection structure and a method for manufacturing the same. The insulated coated conductive particle of the present invention comprises a base particle having conductivity and insulating fine particles coating the surface of the base particle, and has a sparse region in which the number of the insulating fine particles per unit area is small or 0, and a dense region in which the number of the insulating fine particles per unit area is larger than that of the sparse region.

Description

Insulating coated conductive particle, anisotropic conductive film and method for producing same, connection structure and method for producing same

The present invention is a divisional application of inventions having application numbers 201880008563.1 (international application number PCT/JP2018/002350), application dates 2018, 1 month, and 25 days, and having an invention name of "insulating coated conductive particles, anisotropic conductive film, method for producing anisotropic conductive film, connection structure, and method for producing connection structure".

Technical Field

The present invention relates to an insulating coated conductive particle, an anisotropic conductive film, a method for producing an anisotropic conductive film, a connection structure, and a method for producing a connection structure.

Background

Conventionally, for example, in connection of a liquid crystal display and a Tape Carrier Package (TCP), connection of a flexible printed circuit board (FPC) and a TCP, or connection of an FPC and a printed wiring board, an anisotropic conductive film in which conductive particles are dispersed in an adhesive film has been used. In addition, when a semiconductor silicon chip is mounted on a substrate, so-called Chip On Glass (COG) in which a semiconductor silicon chip is directly mounted on a substrate is also performed instead of conventional wire bonding, and here, an anisotropic conductive film is also used.

In recent years, with the development of electronic devices, the density of wiring and the function of circuits have been increased. As a result, a connection structure in which the distance between the connection electrodes is equal to or less than 15 μm, for example, is required, and the bump electrodes of the connection structure are also required to be smaller in area. In order to obtain stable electrical connection in the bump connection with a small area, it is necessary that a sufficient number of conductive particles are interposed between the bump electrode and the circuit electrode on the substrate side.

In order to solve such a problem, patent documents 1 and 2 propose: conductive particles are unevenly distributed on the substrate side at a certain ratio, and the conductive particles are arranged at uniform intervals, whereby the conductive particles between the bump electrodes and the circuit electrodes are more easily captured, and the insulation between the adjacent circuit electrodes which are narrowed is more improved.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication No. 2009-535843

Patent document 2: japanese patent laid-open publication No. 2015-25104

Disclosure of Invention

Problems to be solved by the invention

However, in the above-described conventional method, although the conductive particles are arranged at uniform intervals, the capturing property of the conductive particles can be improved and the connection reliability can be improved, but the anisotropic conductive film melts and flows at the time of circuit connection, and therefore the conductive particles arranged at uniform intervals may also flow, and there is a concern that a problem may occur in that the insulation between adjacent circuit electrodes is lowered.

The present invention aims to provide an insulating coated conductive particle and an anisotropic conductive film which can satisfy both of the securing of the connection reliability between opposing electrodes and the securing of the insulating property between adjacent electrodes in a circuit member in the connection of circuit members having opposing electrodes, a method for producing the anisotropic conductive film, and a connection structure and a method for producing the connection structure which can satisfy both of the connection reliability between opposing electrodes and the insulating property between adjacent electrodes in the circuit member.

Means for solving the problems

The first insulating coated conductive particle comprises a base particle having conductivity and insulating fine particles coating the surface of the base particle, and has a sparse region in which the number of the insulating fine particles per unit area is small or 0, and a dense region in which the number of the insulating fine particles per unit area is larger than that of the sparse region.

The first insulating-coated conductive particle of the present invention can secure insulation when particles are in contact with each other by the dense region, and secure conductive characteristics by the sparse region.

The first insulating coated conductive particle of the present invention may have two of the above-mentioned sparse regions through which a central axis passes, the central axis passing through the center of the above-mentioned base material particle.

In the connection of circuit members having counter electrodes, the insulating coated conductive particles can ensure the connection reliability between the counter electrodes by bringing the two sparse regions into contact with the counter electrodes, respectively, and can ensure the insulation by the dense regions when the particles are brought into contact with other insulating coated conductive particles.

The present invention also provides a second insulating coated conductive particle obtained by removing a part or all of insulating fine particles located in two spherical cap regions of a composite particle including a base particle having conductivity and insulating fine particles, the insulating fine particles coating the surface of the base particle, and the two spherical cap regions being obtained by cutting the base particle with two parallel planes.

In the second insulating coated conductive particle of the present invention, in the connection between circuit members having counter electrodes, the two spherical cap regions from which a part or all of the insulating fine particles are removed can be brought into contact with the counter electrodes, respectively, to ensure the connection reliability between the counter electrodes, and the insulating fine particles located in the spherical zone regions can ensure the insulation when the second insulating coated conductive particle is brought into contact with another insulating coated conductive particle.

The present invention also provides a third insulating coated conductive particle comprising a base particle having conductivity and insulating fine particles coating the surface of the base particle, wherein the insulating fine particles are unevenly distributed in a spherical zone region when the base particle is cut by two parallel planes.

In the third insulating coated conductive particle of the present invention, in the connection between circuit members having counter electrodes, the two spherical cap regions can be brought into contact with the counter electrodes, respectively, to ensure the connection reliability between the counter electrodes, and in the case of contact with another insulating coated conductive particle, the insulating fine particles unevenly distributed in the spherical zone region can ensure the insulating property.

The present invention also provides an anisotropic conductive film comprising a conductive adhesive layer containing the first, second, or third insulating coated conductive particles of the present invention and an adhesive component.

According to the anisotropic conductive film of the present invention, in connection of circuit members having counter electrodes, both the securing of the connection reliability between the counter electrodes and the securing of the insulation between adjacent electrodes in the circuit members can be achieved.

The anisotropic conductive film of the present invention may include the first insulating-coated conductive particles of the present invention having two sparse regions through which a central axis passes, the central axis passing through the center of the base particles, and the insulating-coated conductive particles may be arranged such that an axis passing through the center of the base particles and parallel to the thickness direction of the conductive adhesive layer passes through the two sparse regions.

According to such an anisotropic conductive film, in connection between circuit members having counter electrodes, the two sparse regions of the insulating coated conductive particles can be brought into contact with the counter electrodes more reliably, and in the case of contact with other insulating coated conductive particles, insulation can be ensured by the dense regions of each other. This makes it possible to achieve both the securing of the connection reliability between the opposing electrodes and the securing of the insulation between the adjacent electrodes in the circuit member at a higher level.

The anisotropic conductive film of the present invention may include the second insulating coated conductive particles of the present invention, and the insulating coated conductive particles may be arranged such that an axis passing through the center of the base particles and parallel to the thickness direction of the conductive adhesive layer passes through the two spherical cap regions.

According to such an anisotropic conductive film, in the connection between circuit members having counter electrodes, the two spherical cap regions of the insulating coated conductive particles can be brought into contact with the counter electrodes more reliably, and in the case of contact with another insulating coated conductive particle, the insulating property can be ensured by the insulating fine particles located in the spherical zone region. This makes it possible to achieve both the securing of the connection reliability between the opposing electrodes and the securing of the insulation between the adjacent electrodes in the circuit member at a higher level.

The anisotropic conductive film of the present invention may contain the second or third insulating coated conductive particles of the present invention, and the insulating coated conductive particles may be arranged so that an axis passing through the center of the base particles and parallel to the thickness direction of the conductive adhesive layer is orthogonal to the two parallel planes.

According to such an anisotropic conductive film, in the connection between circuit members having counter electrodes, the two spherical cap regions of the insulating coated conductive particles can be brought into contact with the counter electrodes more reliably, and in the case of contact with another insulating coated conductive particle, the insulating property can be ensured by the insulating fine particles located in the spherical zone region. This makes it possible to achieve both the securing of the connection reliability between the opposing electrodes and the securing of the insulation between the adjacent electrodes in the circuit member at a higher level.

Further, the present invention provides a method for manufacturing an anisotropic conductive film, comprising: a step of preparing composite particles including base particles having conductivity and insulating fine particles covering the surfaces of the base particles; a step of housing composite particles in a hole of a particle housing member provided with a hole having a closed end face; removing a part or all of the insulating fine particles in the spherical cap region of the composite particle exposed from the hole; a step of transferring the composite particles from which the insulating fine particles in the spherical cap region have been removed from the particle housing member onto the first adhesive layer so that the spherical cap region comes into contact with the first adhesive layer, and removing the composite particles by adhering a part of the insulating fine particles of the composite particles to the closed end surface of the particle housing member, thereby providing insulating-coated conductive particles on the first adhesive layer; and a step of bonding the second adhesive layer to the side of the first adhesive layer on which the insulating coated conductive particles are arranged.

According to the method for producing an anisotropic conductive film of the present invention, the insulating coated conductive particles having two spherical cap regions from which a part or all of the insulating fine particles are removed can be provided on the first adhesive layer, and the second adhesive layer is bonded to the first adhesive layer, whereby the conductive adhesive layer containing the insulating coated conductive particles can be easily formed. In the conductive adhesive layer, the insulating coated conductive particles can be arranged so that an axis passing through the center of the base particles and parallel to the thickness direction of the conductive adhesive layer passes through two spherical cap regions.

In the method for manufacturing an anisotropic conductive film of the present invention, the insulating coated conductive particles in the anisotropic conductive film can be aligned by providing the particle-containing member with the holes aligned in order. Further, by adjusting the thicknesses of the first adhesive layer and the second adhesive layer, a conductive adhesive layer containing insulating coated conductive particles so as to be unevenly distributed on one side of both main surfaces of the conductive adhesive layer can be formed.

Further, the present invention provides a connection structure including: a first circuit member having a bump electrode; a second circuit member having a circuit electrode corresponding to the bump electrode; and the first, second, or third insulating coated conductive particles according to the present invention, which are interposed between the bump electrode and the circuit electrode and electrically connect the bump electrode and the circuit electrode.

In the connection structure of the present invention, the bump electrode and the circuit electrode are connected by the first, second, or third insulating-coated conductive particles according to the present invention, and therefore, the connection reliability between the counter electrodes and the insulation between the adjacent electrodes in the circuit member can be satisfied at the same time.

The present invention also provides a method for manufacturing a connection structure, including the steps of: the anisotropic conductive film according to the present invention or the anisotropic conductive film obtained by the method for manufacturing an anisotropic conductive film according to the present invention is interposed between a first circuit member having a bump electrode and a second circuit member having a circuit electrode corresponding to the bump electrode, and the first circuit member and the second circuit member are thermocompression bonded.

According to the method for manufacturing a connection structure of the present invention, a connection structure can be obtained that achieves both the connection reliability between the counter electrodes and the insulation between the adjacent electrodes in the circuit member.

Effects of the invention

According to the present invention, it is possible to provide an insulating coated conductive particle and an anisotropic conductive film which can satisfy both of the securing of the connection reliability between the counter electrodes and the securing of the insulating property between the adjacent electrodes in the circuit member in the connection of the circuit members having the counter electrodes, a method for producing the anisotropic conductive film, and a connection structure and a method for producing the connection structure which can satisfy both of the connection reliability between the counter electrodes and the insulating property between the adjacent electrodes in the circuit member.

Drawings

Fig. 1(a) is a view showing an embodiment of the insulated coated conductive particle according to the present invention, and (b) is a view schematically showing a cross section along the central axis P shown in (a).

FIG. 2 is a view illustrating the maximum diameter and minimum diameter of the insulated coated conductive particle according to the present invention.

Fig. 3(a) is a schematic cross-sectional view showing one embodiment of the anisotropic conductive film according to the present invention, and (b) is an enlarged schematic view of a main portion of the anisotropic conductive film.

FIG. 4 is a schematic cross-sectional view showing a process for producing an anisotropic conductive film according to the present invention.

FIG. 5 is a schematic sectional view showing a subsequent step of FIG. 4.

FIG. 6 is a schematic cross-sectional view showing an anisotropic conductive film obtained through the step of FIG. 5.

FIG. 7 is a view showing an example of arrangement of the insulating coated conductive particles.

FIG. 8 is a schematic cross-sectional view showing one embodiment of a connection structure according to the present invention.

FIG. 9 is a schematic cross-sectional view showing a manufacturing process of the connection structure shown in FIG. 8.

FIG. 10 is a schematic sectional view showing a subsequent step of FIG. 9.

Detailed Description

Preferred embodiments of the insulating coated conductive particle, the anisotropic conductive film, the method for producing the anisotropic conductive film, the connection structure, and the method for producing the connection structure according to the present invention will be described in detail below with reference to the drawings.

[ constitution of insulating coated conductive particles ]

Fig. 1(a) is a view showing an external appearance of an embodiment of the insulated coated conductive particle according to the present invention, and fig. 1(b) is a view schematically showing a cross section taken along a central axis P shown in (a). The insulating coated conductive particles 10 are composed of base particles 1 having conductivity and insulating fine particles 2 coating the surfaces of the base particles 1. The central axis P is an axis passing through the center of the substrate particle 1.

The substrate particle 1 may be a core-shell type particle including a core particle and a metal layer covering at least a part of the surface of the core particle. For example, particles in which the core particles are coated with a metal by plating are exemplified.

Any of metal core particles, organic core particles, and inorganic core particles can be used as the core particles. From the viewpoint of conductivity, organic core particles are preferably used.

The material of the organic core particle is not particularly limited, and examples thereof include: acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polybutadiene.

When the organic core particles are coated by plating or the like, examples of the metal include: metals such as gold, silver, copper, platinum, zinc, iron, palladium, nickel, tin, chromium, titanium, aluminum, cobalt, germanium, cadmium, and the like; ITO, and metal compounds such as solder.

The structure of the metal layer covering the organic core particles is not particularly limited, and the outermost layer is preferably a nickel layer in view of conductivity. In addition, from the viewpoint of conductivity, the outermost layer preferably has protrusions (or projections). A metal layer such as copper may be further provided on the inner side of the nickel layer.

From the viewpoint of absorbing the height unevenness of the electrodes to be connected and from the viewpoint of achieving both the conduction reliability and the insulation reliability, the average primary particle diameter of the base material particles 1 is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 5 μm or less, and still more preferably 2 μm or more and 3 μm or less.

The insulating fine particles 2 may be inorganic oxide fine particles, organic fine particles, or the like, and may be appropriately selected according to desired characteristics such as insulation properties and conductivity. The insulating fine particles 2 are preferably core-shell particles composed of core fine particles containing an organic polymer and shell layers covering at least a part of the surfaces of the core fine particles. The material of the shell layer may be, for example, crosslinked polysiloxane.

From the viewpoint of achieving both conduction reliability and insulation reliability, the average primary particle diameter of the insulating fine particles 2 is preferably not less than 100nm and not more than 500nm, more preferably not less than 200nm and not more than 450nm, and still more preferably not less than 250nm and not more than 350 nm. In particular, if the average primary particle size of the insulating fine particles 2 is 250nm or more, even when the insulating coated conductive particles 10 are aggregated in the connection between circuit members having counter electrodes, it is easy to sufficiently secure the insulation between adjacent circuit electrodes, and if it is 350nm or less, it is easy to sufficiently secure the conduction between the counter circuits even if the insulating fine particles exist in a sparse region where the number of insulating fine particles per unit area is small, which will be described later.

The insulating coated conductive particle 10 of the present embodiment may have a sparse region in which the number of insulating fine particles per unit area is small or 0, and a dense region in which the number of insulating fine particles per unit area is larger than that of the sparse region.

As shown in fig. 1, the insulating coated conductive particle 10 preferably has two of the sparse regions through which a central axis P passes, the central axis P passing through the center of the base particle 1. In other words, the insulating coated conductive particle 10 preferably has a sparse region in the two spherical cap regions and a dense region in the spherical zone region when the base material particle 1 is cut by two parallel planes. In other words, the insulating coated conductive particles 10 are preferably such that the insulating fine particles 2 are unevenly distributed in the spherical zone region when the base material particle 1 is cut by two parallel planes.

Such insulating coated conductive particles 10 can be obtained by removing a part or all of the insulating fine particles 2 located in the two spherical cap regions when the base particles 1 are cut by two parallel planes, the composite particles including the base particles 1 having conductivity and the insulating fine particles 2 coating the surfaces of the base particles 1.

In this embodiment, the boundary between the sparse region and the dense region is not necessarily clear, and an intermediate region having more insulating fine particles per unit area than the sparse region and less insulating fine particles per unit area than the dense region may be provided between the sparse region and the dense region, or each region may be provided such that the number of insulating fine particles per unit area gradually increases from the sparse region to the dense region.

From the viewpoint of reducing the resistance in connection between the opposing circuits, the insulating coated conductive particles 10 preferably have a particle density of the insulating fine particles 2 of 0 particles/. mu.m²2.0 pieces/mum²More preferably, the particle density of the insulating fine particles 2 is 0 particles/. mu.m²1.0 pieces/mum²The sparse region (2) preferably has a particle density of 0 particles/. mu.m²0.5 pieces/mum²The sparse region of (a). The surface area of the base particle 1 is denoted as S₀μm²In the case, the above-mentioned sparse region is preferably 0.5 XS or more₀μm²More preferably 0.7 XS or more₀μm²。

From the viewpoint of improving the insulation between adjacent circuits, the insulating coated conductive particles 10 preferably have a particle density of the insulating fine particles 2 of 2.0 particles/μm²5.0 pieces/mum²More preferably, the dense region of (2) has a particle density of 2.5 particles/μm²4.5 pieces/mum²The dense region (2) preferably has a particle density of the insulating fine particles 2 of 3.0 particles/. mu.m²3.5 pieces/. mu.m²A dense area of (a). The surface area of the base material particle is S₀μm²In this case, the dense region is preferablyGreater than or equal to 0.2 XS₀μm²More preferably 0.3 XS or more₀μm²。

The number of insulating fine particles per unit area in the sparse region and the dense region can be measured by measuring the number of insulating particles present in the center portion of the base particle 1(a circle having a diameter equal to half the diameter of the outer circumference circle of the base particle 1 and concentric with the outer circumference circle) in an SEM photograph of the insulating coated conductive particles. The particle density of the insulating fine particles 2 can be calculated from the number of insulating fine particles per unit area. Regarding the unit area, the surface area of the base material particle 1 is represented as S₀mm²When it is used, it can be set to 0.04 XS₀mm²～0.20×S₀mm²The predetermined area in (2) may be set to 0.17 × S₀mm²。

From the viewpoint of securing an area where electrodes are in direct contact with conductive particles when connecting between opposing circuits, the insulating coated conductive particles 10 preferably contain 0.05 × S or more in the spherical cap region of the base material particle 1₀μm²The region having 0 number of insulating fine particles of (2) more preferably contains 0.10 XS or more₀μm²。

The coverage of the insulating fine particles 2 in the insulating coated conductive particles 10 is preferably 35 to 75%, more preferably 40 to 75%. The coating rate of the insulating fine particles is a value measured by analyzing the center portion of the base particle 1(a circle having a diameter equal to a half of the diameter of the outer circumference circle of the base particle 1 and concentric with the outer circumference circle) in an SEM photograph of the insulating coated conductive particles. Specifically, when the total surface area of the central portion of the base particle 1 in the SEM photograph is W (the area calculated from the particle diameter of the conductive particle), and the surface area of the portion analyzed to be coated with the insulating fine particles 2 in the central portion of the base particle 1 in the SEM photograph is P, the coating ratio is expressed as P/W × 100 (%). In the present embodiment, the surface area P of the portion analyzed to be coated is an average value of the surface areas obtained from 200 SEM photographs of the insulating coated conductive particles.

From the viewpoint of the conduction characteristics, the minimum diameter X' of the insulating coated conductive particles 10 is preferably equal to or larger than the diameter of the base particle 1 and equal to or smaller than the total value of the diameter of the base particle 1 and the diameter of the insulating fine particles 2. From the viewpoint of insulation, the maximum diameter Y' of the insulating coated conductive particles 10 is preferably equal to or greater than the total value of the diameter of the base particles 1 and 2 × (the diameter of the insulating fine particles 2), and equal to or less than the total value of the diameter of the base particles 1 and 6 × (the diameter of the insulating fine particles 2). Fig. 2 shows a case where the minimum diameter X 'of the insulating coated conductive particle 10 shown in fig. 1(b) is the diameter of the base particle 1, and the maximum diameter Y' is the sum of the diameter of the base particle 1 and 2 × (the diameter of the insulating fine particles).

From the viewpoint of compatibility between conductivity and insulation, the ratio X '/Y' of the minimum diameter X 'to the maximum diameter Y' of the insulating coated conductive particles 10 is preferably 0.4 or more and 0.9 or less. When X '/Y' is 0.4 or more, the trapping property of the insulating coated conductive particles 10 can be easily secured even when the bump area of the circuit member is reduced, and when X '/Y' is 0.9 or less, the connection resistance can be easily reduced.

In the production of the insulating coated conductive particle 10 as described above, various methods can be used. Examples thereof include: (i) a method of filling the base particles 1 in a parallel plate provided with a gap having the same particle diameter as the base particles and attaching the insulating fine particles 2 to the filled base particles 1; (ii) a method of preparing composite particles in which the entire surface of the base particles 1 is coated with the insulating fine particles 2, and removing a part of the insulating fine particles 2 of the composite particles.

As a method of adhering the insulating fine particles 2 to the base particles 1 in (i), for example, there can be mentioned: a method in which the base particles 1 and the insulating fine particles 2 are filled between the parallel plates, and then the insulating fine particles 2 are welded to the base particles 1 using an organic solvent or heat.

As a method for obtaining the composite particles in (ii) in which the entire surface of the base particles 1 is coated with the insulating fine particles 2, for example, there can be mentioned: a method in which a charged material such as polyethyleneimine is applied to the base particles 1 and the insulating fine particles 2 are attached by electrostatic force; a method of introducing a functional group capable of bonding the base particles 1 and the insulating fine particles 2 to each other and chemically bonding them to obtain composite particles. As a method for removing a part of the insulating fine particles 2, a method for removing the insulating fine particles 2 in the spherical cap region of the composite particles using an adhesive tape or the like can be cited as a simple method. Further, the method for producing an anisotropic conductive film according to the present invention, which will be described later, is a particularly useful method for producing the insulating coated conductive particles 10 in the production of an anisotropic conductive film.

[ constitution of Anisotropic conductive film ]

Fig. 3(a) is a schematic cross-sectional view showing an embodiment of the anisotropic conductive film according to the present invention, and fig. 3(b) is an enlarged schematic view of a main portion of the anisotropic conductive film. The anisotropic conductive film with a release film 11 shown in the figure is composed of a release film 12 and a conductive adhesive layer (anisotropic conductive film) 13 containing insulating coated conductive particles 10 and an adhesive component. The insulating coated conductive particles 10 are dispersed in the conductive adhesive layer 13. In the present specification, a region not including the insulating coated conductive particles 10 in a cross section obtained by cutting the conductive adhesive layer 13 on a plane perpendicular to the thickness direction may be referred to as an adhesive region, and a region including the insulating coated conductive particles 10 may be referred to as a conductive region.

The release film 12 is formed of, for example, polyethylene terephthalate (PET), polyethylene, polypropylene, or the like. The release film 12 may contain any filler. Further, the surface of the release film 12 may be subjected to a mold release treatment, a plasma treatment, or the like.

As the adhesive component contained in the conductive adhesive layer 13, a monomer and a curing agent can be exemplified. The monomer may be a cationically polymerizable compound, an anionically polymerizable compound, or a radically polymerizable compound. Examples of the cationically polymerizable compound and the anionically polymerizable compound include epoxy compounds.

Examples of the epoxy compound include bisphenol type epoxy resins derived from epichlorohydrin and bisphenol compounds such as bisphenol a, bisphenol F, and bisphenol AD, epoxy novolak resins derived from epichlorohydrin and novolak resins such as phenol novolak and cresol novolak, and various epoxy compounds having two or more glycidyl groups in one molecule, such as glycidyl amine, glycidyl ether, biphenyl, and alicyclic ring.

As the radical polymerizable compound, a compound having a functional group polymerizable by a radical can be used, and examples thereof include acrylic monomers such as (meth) acrylate, maleimide compounds, styrene derivatives, and the like. The radical polymerizable compound may be used in either a monomer or an oligomer state, or a monomer and an oligomer may be mixed and used.

One monomer may be used alone, or two or more monomers may be used in combination.

When an epoxy compound is used, examples of the curing agent include: imidazole type, hydrazide type, boron trifluoride-amine complex, sulfonium salt, aminimide, polyamine salt, dicyandiamide, and the like. From the viewpoint of extending the pot life, it is preferable that these curing agents are coated with a polyurethane-based or polyester-based polymer material and microencapsulated.

The curing agent used in combination with the epoxy compound may be appropriately selected depending on the desired bonding temperature, bonding time, storage stability, and the like. From the viewpoint of high reactivity, it is preferable that the curing agent has a gel time of not more than 10 seconds at a predetermined temperature when the curing agent is prepared into a composition containing an epoxy compound and a curing agent, and from the viewpoint of storage stability, it is preferable that the curing agent has no difference in gel time from a composition after being stored in a constant temperature bath at 40 ℃ for 10 days. From this point of view, the curing agent is preferably a sulfonium salt.

When an acrylic monomer is used, examples of the curing agent include a peroxide compound, an azo compound, and the like, which are decomposed by heating to generate free radicals.

The curing agent used in combination with the acrylic monomer may be appropriately selected depending on the desired bonding temperature, bonding time, storage stability, and the like. From the viewpoint of high reactivity and storage stability, the curing agent is preferably an organic peroxide or azo compound having a 10-hour half-life temperature of 40 ℃ or more and a 1-minute half-life temperature of 180 ℃ or less, more preferably an organic peroxide or azo compound having a 10-hour half-life temperature of 60 ℃ or more and a 1-minute half-life temperature of 170 ℃ or less.

One curing agent may be used alone, or two or more curing agents may be used in combination. The conductive adhesive layer 13 may further contain a decomposition accelerator, a decomposition inhibitor, and the like.

In the case of using either an epoxy compound or an acrylic monomer, the amount of the curing agent is preferably 0.1 to 40 parts by mass, more preferably 1 to 35 parts by mass, based on 100 parts by mass of the total of the monomer and a film-forming material described later, from the viewpoint of obtaining a sufficient reaction rate when the connection time is 10 seconds or less. If the amount of the curing agent is 0.1 parts by mass or more, a sufficient reaction rate can be obtained, and good adhesive strength and low connection resistance can be easily obtained, while if the amount is 40 parts by mass or less, it is easy to prevent the fluidity of the conductive adhesive layer 13 from being lowered and the connection resistance from being increased, and to ensure the storage stability of the anisotropic conductive film.

The conductive adhesive layer 13 may contain a film forming material. The film-forming material is a polymer having an action of facilitating handling of a composition having a low viscosity containing the monomer and the curing agent. By using the film-forming material, the film can be prevented from being easily cracked, or stuck, and an anisotropic conductive film 11 which is easy to handle can be obtained.

As the film forming material, a thermoplastic resin can be suitably used. Examples thereof include: phenoxy resins, polyvinyl formal resins, polystyrene resins, polyvinyl butyral resins, polyester resins, polyamide resins, xylene resins, polyurethane resins, polyacrylic resins, polyester polyurethane resins, and the like. These polymers may also contain siloxane linkages or fluorine substituents. Among the above resins, phenoxy resins are preferably used from the viewpoint of adhesive strength, compatibility, heat resistance, and mechanical strength.

The thermoplastic resin may be used alone or in combination of two or more.

The larger the molecular weight of the thermoplastic resin is, the easier the film formability is obtained, and the melt viscosity affecting the fluidity of the anisotropic conductive film 11 can be set in a wide range. The thermoplastic resin preferably has a weight average molecular weight of 5000 to 150000, more preferably 10000 to 80000. If the weight average molecular weight of the thermoplastic resin is 5000 or more, good film formability is easily obtained, and if 150000 or less, good compatibility with other components is easily obtained.

In the present invention, the weight average molecular weight is a value measured by Gel Permeation Chromatography (GPC) using a calibration curve based on standard polystyrene under the following conditions.

(measurement conditions)

The device comprises the following steps: GPC-8020 manufactured by Tosoh corporation

A detector: RI-8020 manufactured by Tosoh corporation

A chromatographic column: gelpack GLA160S + GLA150S manufactured by Hitachi chemical Co., Ltd

Sample concentration: 120mg/3mL

Solvent: tetrahydrofuran (THF)

Injection amount: 60 μ L

Pressure: 2.94X 10⁶Pa(30kgf/cm²)

Flow rate: 1.00mL/min

The amount of the film-forming material to be blended is preferably 5 to 80% by mass, more preferably 15 to 70% by mass, based on the total amount of the monomer, the curing agent and the film-forming material. When the amount of the film forming material is 5 mass% or more, good film formability is easily obtained, and when the amount is 80 mass% or less, the conductive adhesive layer 13 (particularly, the adhesive region) tends to exhibit good fluidity.

Conductive adhesive layer 13 may further contain a filler, a softening agent, an accelerator, an antioxidant, a colorant, a flame retardant, a thixotropic agent, a coupling agent, a phenol resin, a melamine resin, an isocyanate, and the like.

When conductive adhesive layer 13 contains a filler, further improvement in connection reliability can be expected. The maximum diameter of the filler is preferably smaller than the minimum diameter of the insulating coated conductive particles 10. The content of the filler in the conductive adhesive layer 13 is preferably 5 parts by volume to 60 parts by volume with respect to 100 parts by volume of the conductive adhesive layer. If the amount is within this range, the reliability-improving effect corresponding to the amount added can be easily obtained.

In the conductive adhesive layer (anisotropic conductive film) 13 of the present embodiment, the insulating coated conductive particles 10 are preferably unevenly distributed on one side of both main surfaces of the conductive adhesive layer 13. As shown in fig. 3(b), when the insulated coated conductive particles 10 are unevenly distributed on the side of the conductive adhesive layer 13 on which the release film 12 is provided, the shortest distance between the insulated coated conductive particles 10 and the side may be greater than 0 μm and equal to or less than 1 μm. By setting the shortest distance D within the above range, the flow of the insulating coated conductive particles 10 at the time of pressure bonding can be suppressed, and the trapping performance of the insulating coated conductive particles 10 can be improved.

As shown in fig. 3(b), the insulating coated conductive particles 10 are preferably arranged such that an axis P 'passing through the center of the base particle 1 and parallel to the thickness direction of the conductive adhesive layer 13 passes through two spherical cap regions from which a part or all of the two sparse regions or the insulating fine particles 2 are removed, or such that an axis P' passing through the center of the base particle 1 and parallel to the thickness direction of the conductive adhesive layer 13 is orthogonal to the two parallel planes (the planes dividing the two spherical cap regions and the spherical zone region). In such an anisotropic conductive film 11, the particle diameter X of the insulating coated conductive particles 10 in the direction of the axis P 'and the particle diameter Y in the direction orthogonal to the axis P' are in the relationship of Y > X. When the anisotropic conductive film 11 is in the form of a tape, the direction perpendicular to the axis P' may be referred to as the longitudinal direction thereof.

The particle diameter X is preferably equal to or larger than the diameter of the base particle 1 and equal to or smaller than the total value of the diameter of the base particle 1 and the diameter of the insulating fine particle 2. When the particle diameter X satisfies such a condition, the insulating coated conductive particles 10 are in the following state: at least one of the two spherical cap regions cut on two parallel planes perpendicular to the axis P' has a region where the insulating fine particles 2 are not present. In this case, in the connection between circuit members having counter electrodes, when the insulating coated conductive particles 10 are captured between the counter electrodes, the insulating fine particles 2 are prevented from being held between the base particles 1 of the insulating coated conductive particles 10 and the electrodes, and low-resistance connection is easily performed.

The particle diameter Y is preferably not less than the total value of the diameter of the base particle 1 and 2 × (the diameter of the insulating fine particles 2), and not more than 2 × (the diameter of the base particle 1). When the particle diameter Y satisfies such a condition, the spherical zone region of the insulating coated conductive particles 10 cut on two parallel planes perpendicular to the axis P' has a region coated with the insulating fine particles 2, and even if aggregation of the insulating coated conductive particles 10 occurs in connection between circuit members having counter electrodes, short circuit due to the aggregated particles can be suitably suppressed. The larger the particle diameter Y, the more effective the suppression of short-circuiting, and if the value is 2 x (the diameter of the base material particle 1) or less, it is preferable from the viewpoint of adjusting the particle density of the insulating coated conductive particles 10 in the conductive adhesive layer 13 and controlling the fluidity of the conductive adhesive layer 13 at the time of pressure bonding.

In addition, from the viewpoint of compatibility between conductivity and insulation, the ratio X/Y of the particle diameter X to the particle diameter Y is preferably 0.4 or more and 0.9 or less. If X/Y is 0.4 or more, the trapping property of the insulating coated conductive particles 10 is easily ensured even when the bump area of the circuit member is reduced, and if X/Y is 0.9 or less, the connection resistance is easily reduced.

In the conductive adhesive layer (anisotropic conductive film) 13 of the present embodiment, the above-described conditions are preferably satisfied with respect to an average value of 80% or more of the insulating coated conductive particles.

The particle diameter X, the particle diameter Y, and the shortest distance D can be confirmed by observing a cross section when the anisotropic conductive film 11 is cut along a plane parallel to the thickness direction of the conductive adhesive layer 13 through the center of the base particles 1 of the insulating coated conductive particles 10.

For cross-sectional observation, a processing/observation apparatus such as a Focused Ion Beam (FIB), a Scanning Electron Microscope (SEM), or a Transmission Electron Microscope (TEM) can be used. For example, the cross section of the conductive adhesive layer (anisotropic conductive film) 13 may be cut by FIB, and then observed and measured by SEM. Specifically, the release film 12 side of the release film-attached anisotropic conductive film 11 is fixed to a jig for sample processing/observation using a conductive carbon tape. Then, platinum sputtering treatment was performed from the conductive adhesive layer (anisotropic conductive film) 13 side, and a 10nm platinum film was formed on the conductive adhesive layer (anisotropic conductive film) 13. The anisotropic conductive film with release film 11 was processed from the conductive adhesive layer 13 side using a Focused Ion Beam (FIB), and the processed cross section was observed with a Scanning Electron Microscope (SEM).

The thickness of the adhesive region in the conductive adhesive layer (anisotropic conductive film) 13 can be appropriately set, and for example, the thickness of the adhesive region on the opposite side of the adhesive region satisfying the shortest distance D in the conductive region can be appropriately set according to the height of the bump electrode.

The anisotropic conductive film may have a multilayer structure in which an insulating adhesive layer containing no conductive particles is laminated on the conductive adhesive layer 13.

The insulating adhesive layer may contain the above-mentioned monomer, curing agent and film forming material, as in the case of conductive adhesive layer 13, and may further contain a filler, a softening agent, an accelerator, an antioxidant, a colorant, a flame retardant, a thixotropic agent, a coupling agent, a phenol resin, a melamine resin, an isocyanate and the like.

By laminating the insulating adhesive layer on the conductive adhesive layer 13, the insulating coated conductive particles 10 contained in the anisotropic conductive film are easily unevenly distributed on one surface side of the film. In this case, an anisotropic conductive film can be formed which is composed of a first adhesive region/conductive region/second adhesive region derived from the conductive adhesive layer 13, and a third adhesive region adjacent to the second adhesive region and derived from the insulating adhesive layer. Further, the fluidity of the insulating coated conductive particles 10 and the adhesive region at the time of circuit connection can be arbitrarily adjusted by adjusting the difference in melt viscosity between the conductive adhesive layer 13 and the insulating adhesive layer.

As an example of the adjustment method, a film forming material having a predetermined glass transition temperature (Tg) is included in the conductive adhesive layer 13 and the insulating adhesive layer. In the present embodiment, it is preferable to use a thermoplastic resin (particularly, phenoxy resin) having a Tg of 60 to 180 ℃ as the film forming material contained in the conductive adhesive layer 13, and a thermoplastic resin (particularly, phenoxy resin) having a Tg of 40 to 100 ℃ as the film forming material contained in the insulating adhesive layer. The glass transition temperature is measured by a thermophysical property measuring apparatus such as a Differential Scanning Calorimeter (DSC). For example, the difference in heat amount is measured by weighing the film-forming material in an aluminum sample pan and measuring the film-forming material simultaneously with an empty aluminum sample pan. In this case, since a measurement error may occur due to the influence of melting of the film forming material or the like in the first measurement, it is preferable to measure the glass transition temperature from the second and subsequent measurement data.

The insulating coated conductive particles 10 are preferably arranged in an ordered array in the conductive adhesive layer 13. For example, when viewed from the thickness direction of conductive adhesive layer 13, it is preferable that insulating coated conductive particles 10 be arranged so as to form an arrangement pattern shown in fig. 7. The arrangement pattern includes shapes in which the insulating coated conductive particles 10 are connected to each other in a straight line, and examples thereof include regular triangle, isosceles triangle, regular pentagon, square, rectangle, and an arrangement pattern in which these patterns are inclined. The regular triangular arrangement is a pattern that can realize the closest packing of the insulating coated conductive particles 10, and is an arrangement pattern suitable for increasing the number of insulating coated conductive particles captured between the counter electrodes.

The particle density of the insulating coated conductive particles 10 is preferably 5000 or more/mm²And less than or equal to 40000 pieces/mm². By satisfying this condition, it is possible to preferably satisfy both the securing of the connection reliability between the counter electrodes and the securing of the insulation between the adjacent electrodes in the circuit member.

[ method for producing Anisotropic conductive film ]

Next, an embodiment of the method for manufacturing an anisotropic conductive film according to the present invention will be described with reference to fig. 4 to 6.

The method for manufacturing an anisotropic conductive film according to the present embodiment shown in fig. 4 to 6 includes:

step 1 of preparing composite particles 20, the composite particles 20 having conductive base particles 1 and insulating fine particles 2 covering the surfaces of the base particles 1;

step 2 of accommodating the composite particles 20 in the holes 32 of the particle accommodating member 30 provided with the holes 32 having the closed end faces S (see fig. 4 (a));

a step 3 of removing a part or all of the insulating fine particles 2 located in the spherical cap region 3 of the composite particle 20 exposed from the hole 32 (see fig. 4 (b));

step 4 of transferring the composite particles 20 from the particle housing member 30 to the first adhesive layer 13a with the crown region 3 side of the composite particles 20 from which the insulating fine particles 2 of the crown region 3 have been removed in contact with the first adhesive layer 13a, and removing a part of the insulating fine particles 2 of the composite particles 20 by adhering to the closed end surface S of the particle housing member 30, thereby providing the insulating coated conductive particles 10 on the first adhesive layer 13a (see fig. 5(a) and (b)); and

step 5 is to adhere second adhesive layer 13b to the side of first adhesive layer 13a on which insulated coated conductive particles 10 are arranged (see fig. 5 (c)).

The composite particles 20 in step 1 may be prepared as described in the method of (ii) above.

Examples of the material of the particle housing member 30 used in step 2 include a cured product of a radical polymerizable compound such as acrylate or methacrylate. As the shape of the hole 32, as long as the composite particle 20 can be accommodated and the spherical cap region 3 of the composite particle 20 can protrude from the particle accommodating member 30, for example, there are: cylinder, cone, prism, pyramid. Examples of the shape of the closed end surface S include a circular shape (spherical shape) and a polygonal shape.

The holes 32 are preferably arranged in an ordered array (for example, an array shown in fig. 7), whereby the conductive adhesive layer 13 in which the insulating coated conductive particles 10 are arranged in the array pattern can be formed.

Examples of a method for removing the insulating fine particles 2 of the composite particles 20 located in the spherical cap region 3 include a method of scraping with a spatula made of urethane rubber, metal, or the like, and a method of scraping with a brush or the like.

Examples of the material constituting the first adhesive layer 13a include the monomer, the curing agent, and the film-forming material contained in the conductive adhesive layer 13. First adhesive layer 13a may further contain a filler, a softening agent, an accelerator, an aging inhibitor, a colorant, a flame retardant, a thixotropic agent, a coupling agent, a phenol resin, a melamine resin, an isocyanate, and the like.

In the present embodiment, as shown in fig. 5(a), a laminate in which the first adhesive layer 13a is formed on the release film 12 can be used. The thickness of the first adhesive layer 13a can be set as appropriate according to the height of the bump electrode.

In addition, when the second adhesive layer 13b is bonded, a laminate in which the second adhesive layer 13b is formed on the release film 12 may be used. The thickness of the second adhesive layer 13b can be set as appropriate according to the height of the bump electrode. Examples of the material constituting the second adhesive layer 13b include the monomer, the curing agent, and the film-forming material contained in the conductive adhesive layer 13. Second adhesive layer 13b may further contain a filler, a softening agent, an accelerator, an aging inhibitor, a colorant, a flame retardant, a thixotropic agent, a coupling agent, a phenol resin, a melamine resin, an isocyanate, and the like.

As a method of bonding, for example, a laminating method of bonding while heating an adhesive is cited. Further, if a vacuum heating laminator which performs lamination under reduced pressure in addition to heating is used, inclusion of air bubbles can be reduced at the time of bonding.

Through the above steps 1 to 5, the anisotropic conductive film with a release film having a laminated structure in which the release film 12, the conductive adhesive layer (anisotropic conductive film) 13 containing the insulating coated conductive particles 10 and the adhesive component, and the release film 12 are laminated in this order as shown in fig. 6 can be obtained.

In the present embodiment, from the viewpoint of causing the insulating coated conductive particles 10 to be unevenly distributed on one surface side of the conductive adhesive layer 13, it is preferable that the ratio Da/Db between the thickness Da of the first adhesive layer 13a and the thickness Db of the second adhesive layer 13b is 20/1 to 15/5.

[ constitution of connection Structure ]

Fig. 8 is a schematic cross-sectional view showing one embodiment of a connection structure according to the present invention. As shown in the drawing, the connection structure body 50 is configured to include a first circuit member 52 and a second circuit member 53 that face each other, and a cured product 54 of a conductive adhesive layer (anisotropic conductive film) that connects these circuit members 52, 53.

The first circuit member 52 is, for example, a Tape Carrier Package (TCP), a printed wiring board, a semiconductor silicon chip, or the like. The first circuit member 52 has a plurality of bump electrodes 6 on the mounting surface 5a side of the main body portion 5. The bump electrode 6 is formed in a rectangular shape in plan view, for example, and has a thickness of 3 μm or more and less than 18 μm, for example. The bump electrode 6 is formed from a material such as Au, and is more easily deformed than the insulating coated conductive particles 10 contained in the cured product 54 of the conductive adhesive (anisotropic conductive film). An insulating layer may be formed on the mounting surface 5a at a portion where the bump electrode 6 is not formed.

The second circuit member 53 is, for example, ITO or IZO used for liquid crystal displays, or a glass substrate, a plastic substrate, a flexible printed circuit board (FPC), a ceramic wiring board, or the like on which a circuit is formed using metal or the like. As shown in fig. 6, the second circuit member 53 has a plurality of circuit electrodes 8 corresponding to the bump electrodes 6 on the mounting surface 7a side of the main body portion 7. The circuit electrodes 8 are formed in a rectangular shape in plan view, for example, and have a thickness of about 100nm, for example, as in the bump electrodes 6. The surface of the circuit electrode 8 is made of, for example, one or two or more materials selected from gold, silver, copper, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, Indium Tin Oxide (ITO), and Indium Zinc Oxide (IZO). An insulating layer may be formed on the mounting surface 7a at a portion where the circuit electrodes 8 are not formed.

The cured product 54 can be formed, for example, by using the anisotropic conductive film with release film 11 shown in fig. 3(a), and can be used as a cured product of the conductive adhesive layer (anisotropic conductive film) 13. In the present embodiment, the layer in which the insulating coated conductive particles 10 are dispersed is referred to as a conductive adhesive layer 13 for convenience of description, but the adhesive component itself constituting the layer is nonconductive.

The insulating coated conductive particles 10 may be unevenly distributed on the second circuit member 53 side, and may be interposed between the bump electrodes 6 and the circuit electrodes 8 in a state of being slightly deformed flatly by pressure bonding. Thereby, the electrical connection between the bump electrode 6 and the circuit electrode 8 is achieved. In addition, the insulating coated conductive particles 10 are spaced apart in a pattern between the adjacent bump electrodes 6 and between the adjacent circuit electrodes 8 and 8, thereby achieving electrical insulation between the adjacent bump electrodes 6 and between the adjacent circuit electrodes 8 and 8.

[ method for producing connection Structure ]

Fig. 9 and 10 are schematic cross-sectional views showing a manufacturing process of the connection structure shown in fig. 8. In forming the connection structure 50, first, the release film 12 is peeled off from the anisotropic conductive film with release film 11, and the conductive adhesive layer (anisotropic conductive film) 13 is laminated on the second circuit member 53 so as to face the mounting surface 7 a. Next, as shown in fig. 10, the first circuit member 52 is disposed on the second circuit member 53 on which the conductive adhesive layer (anisotropic conductive film) 13 is laminated so that the bump electrodes 6 face the circuit electrodes 8. Then, the first circuit member 52 and the second circuit member 53 are pressed in the thickness direction while heating the conductive adhesive layer (anisotropic conductive film) 13.

As a result, the adhesive component of the conductive adhesive layer (anisotropic conductive film) 13 flows, the distance between the bump electrode 6 and the circuit electrode 8 is shortened, the insulating coated conductive particles 10 are engaged with each other, and the conductive adhesive layer 13 is cured in the above state. By curing the conductive adhesive layer 13, a cured product 54 of the conductive adhesive layer (anisotropic conductive film) 13 is formed in a state where the bump electrodes 6 and the circuit electrodes 8 are electrically connected and the adjacent bump electrodes 6 and 6 are electrically insulated from each other and the adjacent circuit electrodes 8 and 8 are electrically insulated from each other, and the connection structure 50 shown in fig. 8 is obtained. In the obtained connection structure body 50, the cured product 54 of the conductive adhesive layer (anisotropic conductive film) 13 can sufficiently prevent a change over time in the distance between the bump electrode 6 and the circuit electrode 8, and can ensure long-term reliability of the electrical characteristics.

The heating temperature at the time of connection is preferably not lower than a temperature at which the polymerization active species are generated in the curing agent and the polymerization of the polymerizable monomer starts. The heating temperature is, for example, 80 to 200 ℃ and preferably 100 to 180 ℃. The heating time is, for example, 0.1 to 30 seconds, preferably 1 to 20 seconds. If the heating temperature is less than 80 ℃, the curing speed becomes slow, and if it exceeds 200 ℃, undesirable side reactions tend to proceed. If the heating time is less than 0.1 second, the curing reaction cannot sufficiently proceed, and if it exceeds 30 seconds, the productivity of the cured product 54 is lowered, and further, an undesirable side reaction is likely to proceed.

According to the method of manufacturing a connection structure of the present embodiment, by using the conductive adhesive layer (anisotropic conductive film) 13 containing the insulating coated conductive particles 10, it is possible to obtain a connection structure that can satisfy both the connection reliability between the counter electrodes and the insulation between the adjacent electrodes in the circuit member.

Examples

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[ formation of adhesive layer ]

The adhesive layers were formed by the following methods.

(adhesive layer 1)

In a 3000mL three-necked flask equipped with a serpentine cooling tube, a calcium chloride tube, and a polytetrafluoroethylene stirring rod connected to a stirring motor, 45g of 4,4 ' - (9-fluorenylidene) -diphenol (Sigma-Aldrich Japan K.K.) and 50g of 3,3 ', 5,5 ' -tetramethylbiphenol diglycidyl ether (Mitsubishi chemical corporation: YX-4000H) were dissolved in 1000mL of N-methylpyrrolidone to prepare a reaction solution. To this solution, 21g of potassium carbonate was added, and the mixture was stirred while being heated to 110 ℃ by a hood-type electric heater. After stirring for 3 hours, the reaction mixture was added dropwise to a beaker containing 1000mL of methanol, and the resulting precipitate was filtered off by suction filtration. The filtered precipitate was washed 3 times with 300mL of methanol to obtain 75g of phenoxy resin a.

The molecular weight and the dispersibility of the phenoxy resin a were measured by Gel Permeation Chromatography (GPC) under the following conditions, and as a result, Mn 15769, Mw 38045, and Mw/Mn 2.413 were calculated in terms of polystyrene using a standard curve based on standard polystyrene.

(measurement conditions)

The device comprises the following steps: GPC-8020 manufactured by Tosoh corporation

A detector: RI-8020 manufactured by Tosoh corporation

A chromatographic column: gelpack GLA160S + GLA150S manufactured by Hitachi chemical Co., Ltd

Sample concentration: 120mg/3mL

Solvent: tetrahydrofuran (THF)

Injection amount: 60 μ L

Pressure: 2.94X 10⁶Pa(30kgf/cm²)

Flow rate: 1.00mL/min

The glass transition temperature of the phenoxy resin a was measured under the following conditions, and found to be 160 ℃.

(measurement conditions)

Using a differential scanning calorimetry apparatus (Pyeis, manufactured by perkin elmer, ltd.) in a nitrogen atmosphere, the temperature-raising rate: the measurement was carried out 2 times at a temperature of 30 to 250 ℃ at 10 ℃/min, and the result of the 2 nd measurement was defined as the glass transition temperature.

Subsequently, 50 parts by mass of bisphenol A type epoxy resin (manufactured by Mitsubishi chemical corporation: jER828), 5 parts by mass of 4-hydroxyphenylmethylbenzylsulfonium hexafluoroantimonate as a curing agent, and 50 parts by mass of phenoxy resin a as a film forming material were dissolved in methyl ethyl ketone and mixed to prepare an adhesive paste.

The obtained adhesive paste was applied to a 50 μm thick PET resin film using a coater, and hot air-dried at 70 ℃ for 5 minutes to form an adhesive layer 1 having a thickness of 15 μm.

(adhesive layer 2)

Adhesive layer 2 having a thickness of 0.8 μm was formed in the same manner as adhesive layer 1.

(adhesive layer 3)

An adhesive paste was prepared by mixing 45 parts by mass of a bisphenol F-type epoxy resin (manufactured by Mitsubishi chemical corporation: jER807), 5 parts by mass of 4-hydroxyphenylmethylbenzylsulfonium hexafluoroantimonate as a curing agent, and 55 parts by mass of a phenoxy resin YP-70 (manufactured by Nippon iron Co., Ltd.) as a film-forming material.

The obtained adhesive paste was applied to a 50 μm thick PET resin film using a coater, and hot air-dried at 70 ℃ for 5 minutes to form an adhesive layer 3 having a thickness of 15 μm.

[ preparation of composite particles ]

Composite particles were prepared by the following methods.

(substrate particles)

After degreasing with an alkali, 3g of crosslinked polystyrene particles (resin fine particles) having an average particle diameter of 3.0 μm were neutralized with an acid. Subsequently, the resin fine particles were added to 100mL of a cationic polymer solution adjusted to pH6.0, stirred at 60 ℃ for 1 hour, filtered through a membrane filter (manufactured by Millipore corporation) having a diameter of 3 μm, and washed with water. The resin fine particles after washing with water were added to 100mL of a palladium catalyst solution containing 8 mass% of Atotech Neogenanth 834 (trade name, manufactured by Anmet Japan Co., Ltd.) as a palladium catalyst, stirred at 35 ℃ for 30 minutes, filtered, and washed with water.

Then, the washed resin fine particles were added to a 3g/L sodium hypophosphite solution to obtain surface-activated resin fine particles (resin core particles). The resin core particles, 1000mL of water, and sodium malate (concentration: 20g/L) were put into a 2000mL glass beaker and dispersed by ultrasonic waves. Subsequently, the pH was adjusted to 5.5 or less while stirring with a fluorine stirring blade (600rpm), and the dispersion was heated to 80 ℃. To this was added an initial thin film plating solution prepared by mixing SEK670 (product name of japan kani ltd., ltd.) as an electroless nickel plating solution at a ratio of (SEK670-0)/(SEK670-1) of 1.8 at 7 ml/min using a metering pump, and after about 30 seconds, the reduction reaction was started, bubbles were generated from the bath solution and the entire bath solution was turned black from gray. After the initial thin film formation was completed, two liquids, a thickening bath obtained by mixing nickel sulfate (224 g/L in concentration) and sodium malate (305 g/L in concentration) and a thickening bath obtained by mixing sodium hypophosphite (534 g/L in concentration) and sodium hydroxide (34 g/L in concentration), were added at the same time at 13 ml/min without interruption. Then, stirring was performed until generation of bubbles was stopped, and as a result, the entire bath was changed from black to gray. By this plating treatment, a nickel plating layer covering the resin core particles is formed. The diameter of the substrate particles was measured by SEM and found to be 3.3 μm.

(insulating Fine particles)

A500 mL three-necked flask was charged with 7.5g of a silane coupling agent (3-acryloyloxypropyltrimethoxysilane, manufactured by shin-Etsu chemical Co., Ltd.: KBM-5103), 6.9g of methacrylic acid (manufactured by Wako pure chemical industries Co., Ltd.), 4.1g of methyl acrylate (manufactured by Wako pure chemical industries Co., Ltd.), 0.36g of 2, 2' -azobis (isobutyronitrile), and 350g of acetonitrile, and mixed. The dissolved oxygen was replaced with nitrogen (100 mL/min) for 1 hour, and then the mixture was heated to 80 ℃ and subjected to polymerization for 6 hours to obtain organic-inorganic composite particles having a primary particle diameter of 300 nm. The dispersion containing the organic-inorganic composite particles was placed in a 20mL container, and the unreacted monomer was removed by centrifugation at 3000r.p.m. (Kokusen, K.K.: H-103N) for 30 minutes. Further, 20mL of methanol was added, and ultrasonic dispersion was performed to perform centrifugal separation again. Triethylamine was added thereto in an equimolar amount relative to the amount of carboxyl groups as a curing catalyst, methanol was added thereto, and ultrasonic dispersion was performed to perform a crosslinking reaction. After centrifugation again, triethylamine was removed, and the obtained insulating fine particles were dispersed in methanol.

(composite particle 1)

< step of Forming surface functional groups on substrate particles >

Mercaptoacetic acid (trade name, manufactured by Wako pure chemical industries, Ltd.) in an amount of 8mmol was dissolved in 200ml of methanol, and 10g of the base particles prepared above was added thereto. Stirred at room temperature (25 ℃ C.) for 2 hours using a Three-One Motor (product of New eastern science corporation, trade name: BL3000) equipped with a stirring blade having a diameter of 45mm, and washed with methanol

The membrane filter (manufactured by Millipore corporation: coating type membrane filter) was subjected to filtration to obtain 10g of substrate particles having a carboxyl group as a surface functional group.

< step of adsorbing polyelectrolyte on substrate particles >

A30% by mass polyethyleneimine aqueous solution (trade name: 30% polyethyleneimine P-70 solution, manufactured by Wako pure chemical industries, Ltd.) containing polyethyleneimine having a weight average molecular weight of 70000 was diluted with ultrapure water to obtain a 0.3% by mass polyethyleneimine aqueous solution. To the 0.3 mass% polyethyleneimine aqueous solution, 10g of the base particles having the carboxyl groups introduced therein was added. Stirred at room temperature (25 ℃) for 15 minutes by

The membrane filter of (3) is used for filtration to obtain particles having polyethyleneimine as a polymer electrolyte adsorbed on the surface thereof. The particles were mixed with 200g of ultrapure water and stirred at room temperature (25 ℃) for 5 minutes, followed by filtration. The particles obtained by filtration were washed 2 times with 200g of ultrapure water on the membrane filter, and the polyethyleneimine which had not been adsorbed to the particles was removed.

< Process for coating base particles with insulating Fine particles >

While 50g of a 2 mass% insulating fine particle dispersion obtained by diluting the insulating fine particles prepared above with 2-propanol (manufactured by Wako pure chemical industries, Ltd.) was added dropwise to 10g of the base particles having the polyethyleneimine adsorbed thereon, the mixture was stirred at room temperature (25 ℃) for 30 minutes, thereby obtaining composite particles 1 composed of the base particles and the insulating fine particles coated therewith. The composite particle 1 taken out by filtration was put into a mixture of 50g of silicone oligomer having a weight average molecular weight of 1000 (SC-6000, manufactured by Hitachi chemical Coated Sand Co., Ltd.) and 150g of methanol, stirred at room temperature (25 ℃ C.) for 1 hour, and filtered. Finally, the composite particles were put into toluene (manufactured by Wako pure chemical industries, Ltd.) and stirred for 3 minutes, followed by filtration.

< fractionation step >

The obtained composite particles 1 were vacuum-dried at 150 ℃ for 1 hour. Thereafter, the aggregate was removed by a cyclone type screen classifier (refreshing corporation).

(composite particle 2)

In the same manner as in the composite particle 1, 10g of the substrate particles having a carboxyl group as a surface functional group were obtained.

A30% by mass polyethyleneimine aqueous solution (trade name: 30% polyethyleneimine P-70 solution, manufactured by Wako pure chemical industries, Ltd.) containing polyethyleneimine having a weight average molecular weight of 70000 was diluted with ultrapure water to obtain a 0.3% by mass polyethyleneimine aqueous solution. To the 0.3 mass% polyethyleneimine aqueous solution, 10g of the base particles having the carboxyl groups introduced therein was added. Stirred at room temperature (25 ℃) for 15 minutes by

The membrane filter of (3) is used for filtration to obtain particles having polyethyleneimine as a polymer electrolyte adsorbed on the surface thereof. The particles were mixed with 200g of ultrapure water and stirred at room temperature (25 ℃) for 5 minutes, followed by filtration. The particles obtained by filtration were washed 2 times with 200g of ultrapure water on the membrane filter, and the polyethyleneimine which had not been adsorbed to the particles was removed.

Composite particles 2 composed of conductive particles and insulating fine particles 1 coated with the conductive particles were obtained by adding 50g of a 2 mass% insulating fine particle dispersion obtained by diluting the insulating fine particles prepared above with 2-propanol (manufactured by Wako pure chemical industries, Ltd.) dropwise to 10g of base particles having polyethyleneimine adsorbed thereon, and stirring the mixture at room temperature (25 ℃) for 30 minutes. The composite particles 2 obtained by filtration were put into a mixture of 50g of a silicone oligomer having a weight average molecular weight of 1000 (SC-6000, manufactured by Hitachi chemical Coated Sand Co., Ltd.) and 150g of methanol, stirred at room temperature (25 ℃ C.) for 1 hour, and then filtered. Finally, the composite particles were put into toluene (manufactured by Wako pure chemical industries, Ltd.) and stirred for 3 minutes, followed by filtration.

The obtained composite particles 2 were vacuum-dried at 150 ℃ for 1 hour. Thereafter, the aggregate was removed by a cyclone type screen classifier (refreshing corporation).

(composite particles 3)

In the same manner as in the composite particle 1, 10g of the substrate particles having a carboxyl group as a surface functional group were obtained.

A30% by mass polyethyleneimine aqueous solution (trade name: 30% polyethyleneimine P-70 solution, manufactured by Wako pure chemical industries, Ltd.) containing polyethyleneimine having a weight average molecular weight of 70000 was diluted with ultrapure water to obtain a 0.3% by mass polyethyleneimine aqueous solution. To the 0.3 mass% polyethyleneimine aqueous solution, 10g of the base particles having the carboxyl groups introduced therein was added. Stirred at room temperature (25 ℃) for 15 minutes by

The membrane filter of (3) is used for filtration to obtain particles having polyethyleneimine as a polymer electrolyte adsorbed on the surface thereof. The particles were mixed with 200g of ultrapure water and stirred at room temperature (25 ℃) for 5 minutes, followed by filtration. The particles obtained by filtration were washed 2 times with 200g of ultrapure water on the membrane filter, and the polyethyleneimine which had not been adsorbed to the particles was removed.

Composite particles 3 comprising conductive particles and insulating fine particles 1 coated with the conductive particles were obtained by stirring 10g of base particles having polyethyleneimine adsorbed thereon for 30 minutes at room temperature (25 ℃) while dropping 50g of a 2 mass% insulating fine particle dispersion obtained by diluting insulating fine particles with 2-propanol (manufactured by Wako pure chemical industries, Ltd.). The composite particles 3 obtained by filtration were put into a mixture of 50g of a silicone oligomer having a weight average molecular weight of 1000 (SC-6000, manufactured by Hitachi chemical Coated Sand Co., Ltd.) and 150g of methanol, stirred at room temperature (25 ℃ C.) for 1 hour, and then filtered. Finally, the composite particles were put into toluene (manufactured by Wako pure chemical industries, Ltd.) and stirred for 3 minutes, followed by filtration.

The obtained composite particles 3 were vacuum-dried at 150 ℃ for 1 hour. Thereafter, the aggregate was removed by a cyclone type screen classifier (refreshing corporation).

[ preparation of particle housing Member ]

The particle housing members shown below were prepared, respectively.

(particle housing Member 1)

The number of cylindrical holes (diameter: 4.0 μm, depth: 3.8 μm) having closed end faces (bottom faces) was 29000/mm²Was arranged in a regular triangle pattern on a sheet having a thickness of 5.0 μm obtained by polymerization of methacrylate.

(particle housing Member 2)

The number of holes having a cylindrical shape (diameter: 4.0 μm, depth: 3.8 μm) with closed end faces (bottom faces) was adjusted to 20000/mm²Was arranged in a square pattern on a 5.0 μm thick sheet obtained by polymerization of methacrylate.

(particle housing member 3)

Holes having a cylindrical shape (diameter 4.6 μm, depth 3.8gm) with closed end faces (bottom faces) were arranged at 25000/mm²Was arranged in a regular triangle pattern on a sheet having a thickness of 5.0 μm obtained by polymerization of methacrylate.

(particle housing member 4)

The number of holes having a cylindrical shape (diameter 5.2 μm, depth 3.8 μm) with closed end faces (bottom faces) was adjusted to 20000/mm²Is arranged in a thickness of regular triangleDegree 5.0. mu.m, obtained by polymerization of methacrylate.

(particle housing member 5)

The number of the holes having a cylindrical shape (diameter: 3.7 μm, depth: 3.8 μm) with a closed end face (bottom face) was 29000/mm²Was arranged in a regular triangle pattern on a sheet having a thickness of 5.0 μm obtained by polymerization of methacrylate.

[ production of Anisotropic conductive film ]

(example 1)

In the same manner as in the method shown in fig. 4(a) and (b), the composite particles 1 are accommodated in the holes of the particle accommodating member 1, and the insulating fine particles in the spherical cap region of the composite particles exposed from the holes are removed using a spatula made of urethane rubber with a horizontal end face. It was confirmed by observation with SEM that 54.7 μm was provided in the spherical cap region of the composite particle by the above operation²The number of insulating fine particles of (2) is 0.

Next, the adhesive layer 1 was provided with 29000 pieces/mm in size in the same manner as in the method shown in FIGS. 5(a) and (b)²The particle density of (2) is arranged in regular triangle-shaped insulating coated conductive particles. At this time, observation by SEM confirmed that: 47.9 μm is provided on the opposite side of the portion of the insulation-coated conductive particles in contact with the adhesive layer 1 by the insulating fine particles adhering to the bottom surfaces of the holes of the particle housing member 1²The number of insulating fine particles of (2) is 0.

Next, the adhesive layer 2 was bonded to the side of the adhesive layer 1 on which the insulating coated conductive particles were arranged by a hot roll laminator heated to 40 ℃, thereby obtaining an anisotropic conductive film in which a conductive adhesive layer was provided between two PET resin films.

(example 2)

Using the particle-containing member 2, 20000 particles/mm are provided on the adhesive layer 1²An anisotropic conductive film was obtained in the same manner as in example 1, except that the particle density of (1) was changed to square insulating coated conductive particles.

(example 3)

An anisotropic conductive film was obtained in the same manner as in example 1, except that the composite particles 2 were used instead of the composite particles 1 and the particle housing member 3 was used instead of the particle housing member 1. In this case, it was also confirmed that 50.2 μm was provided in the spherical cap region of the composite particle²The number of insulating fine particles of (2) is 0, and it can be confirmed that 48.7 μm is provided on the opposite side of the portion of the insulating coated conductive particles in contact with the adhesive layer 1²The number of insulating fine particles of (2) is 0.

(example 4)

An anisotropic conductive film was obtained in the same manner as in example 1, except that the composite particles 3 were used instead of the composite particles 1 and the particle housing member 4 was used instead of the particle housing member 1. In this case, it was also confirmed that 53.3 μm was provided in the spherical cap region of the composite particle²The number of insulating fine particles of (2) is 0, and it can be confirmed that 48.7 μm is provided on the opposite side of the portion of the insulating coated conductive particles in contact with the adhesive layer 1²The number of insulating fine particles of (2) is 0.

(example 5)

An anisotropic conductive film was obtained in the same manner as in example 1, except that the particle housing member 5 was used instead of the particle housing member 1. In this case, it was also confirmed that 52.6 μm was provided in the spherical cap region of the composite particle²The number of insulating fine particles of (2) is 0, and it can be confirmed that 47.9 μm is provided on the opposite side of the portion of the insulating coated conductive particles in contact with the adhesive layer 1²The number of insulating fine particles of (2) is 0.

(example 6)

An anisotropic conductive film was obtained in the same manner as in example 1, except that the adhesive layer 3 was used instead of the adhesive layer 1.

[ evaluation of Anisotropic conductive film ]

The anisotropic conductive films of examples 1 to 6 were subjected to cross-sectional processing and cross-sectional observation by FIB-SEM. In addition, the cross-sectional observation was performed on a surface parallel to the thickness direction of the conductive adhesive layer passing through the center of the base particles of the insulating-coated conductive particles, and the particle diameter X in the direction parallel to the thickness direction of the conductive adhesive layer and the particle diameter Y in the direction orthogonal to the thickness direction of the conductive adhesive layer of the insulating-coated conductive particles at this time were measured, and the shortest distance D between the insulating-coated conductive particles and the surface of the conductive adhesive layer was measured. The results are shown in table 1.

[ Table 1]

[ production of connection Structure ]

As a first circuit member, an IC chip having a linear arrangement structure in which bump electrodes are arranged in a row (outer shape 2mm × 20mm, thickness 0.55mm, size of the bump electrodes 100 μm × 30 μm, inter-bump electrode distance 8 μm, and bump electrode thickness 15 μm) was prepared. As a second circuit member, a member was prepared in which an ITO wiring pattern (pattern width 21 μm, gap between electrodes 17 μm) was formed on the surface of a glass substrate (manufactured by Corning Corp.: #1737, 38 mm. times.28 mm, thickness 0.3 mm).

One PET resin film of the anisotropic conductive films (2.5 mm. times.25 mm) according to examples 1 to 6 was peeled off, and the film was thermally pressed at 80 ℃ and 0.98MPa (10 kgf/cm) using a thermal press apparatus comprising a stage (150 mm. times.l 50mm) including a ceramic heater and a tool (3 mm. times.20 mm)²) Heating and pressing were performed for 2 seconds under the conditions of (1) to bond the conductive adhesive layer to the glass substrate.

Next, after the other PET resin film of the anisotropic conductive film was peeled off to align the bump electrodes of the IC chip with the circuit electrodes of the glass substrate, heating and pressing were performed for 5 seconds under conditions of a maximum measured temperature of 170 ℃ of the conductive adhesive layer and 70MPa based on an area conversion pressure of the bump electrodes using a thermocompression bonding apparatus including a stage (150mm × l50mm) including a ceramic heater and a tool (3mm × 20mm), thereby obtaining a connection structure.

[ evaluation of connection Structure ]

The obtained connection structure was evaluated for connection resistance between the bump electrode and the circuit electrode and insulation resistance between the adjacent circuit electrodes. The connection resistance was evaluated by a four-terminal measurement method, and the average value of 14 sites was used. In the evaluation of insulation resistance, a voltage of 50V was applied to the connection structure, and insulation resistance between circuit electrodes at 1440 point was measured. The results are shown in table 2.

[ Table 2]

	Connecting resistance omega]	Insulation resistance omega]
			Example 1	1.0	＞108
Example 2	1.1	＞108
			Example 3	1.1	＞108
Example 4	1.0	＞108
			Example 5	1.1	＞108
Example 6	1.0	＞108

As shown in table 2, the connection structures produced using the anisotropic conductive films of examples 1 to 6 had a connection resistance value of 1.2Q or less and sufficient insulation resistance.

Description of the symbols

1: substrate particles, 2: insulating fine particles, 3: spherical cap region, 6: bump electrode, 8: circuit electrode, 10: insulating coated conductive particles, 11: anisotropic conductive film with release film, 12: release film, 13: conductive adhesive layer (anisotropic conductive film), 13 a: first adhesive layer, 13 b: second adhesive layer, 20: composite particles, 30: particle accommodation member, 32: hole, 50: connection structure, 52: first circuit member, 53: second circuit member, 54: and (5) curing the product.

Claims (11)

1. An insulated coated conductive particle comprising a base particle having conductivity and an insulating fine particle coating the surface of the base particle,

and has a sparse region in which the number of insulating fine particles per unit area is small or 0, and a dense region in which the number of insulating fine particles per unit area is larger than that of the sparse region.

2. The insulation-coated conductive particle according to claim 1, which has two of the sparse regions through which a central axis passes, the central axis passing through the center of the substrate particle.

3. An insulating coated conductive particle, which is obtained by removing a part or all of insulating fine particles located in two spherical cap regions of a composite particle comprising a base particle and the insulating fine particles, wherein the base particle has conductivity, the insulating fine particles coat the surface of the base particle, and the two spherical cap regions are obtained by cutting the base particle with two parallel planes.

4. An insulated coated conductive particle comprising a base particle having conductivity and an insulating fine particle coating the surface of the base particle,

the insulating fine particles are biased to a spherical zone region when the base material particles are cut by two parallel planes.

5. An anisotropic conductive film comprising a conductive adhesive layer containing the insulation-coated conductive particles according to any one of claims 1 to 4 and an adhesive component.

6. The acf of claim 5 comprising the insulation-coated conductive particle of claim 2,

the insulating coated conductive particles are arranged such that an axis passing through the center of the base particles and parallel to the thickness direction of the conductive adhesive layer passes through the two sparse regions.

7. The acf of claim 5 comprising the insulation-coated conductive particle of claim 3,

the insulating coated conductive particles are arranged such that an axis passing through the center of the base particles and parallel to the thickness direction of the conductive adhesive layer passes through both the spherical cap regions.

8. The acf of claim 5 comprising the insulation-coated conductive particle of claim 3 or 4,

the insulating coated conductive particles are arranged so that axes passing through the centers of the base particles and parallel to the thickness direction of the conductive adhesive layer are orthogonal to the two parallel planes.

9. A method for manufacturing an anisotropic conductive film, comprising:

preparing composite particles including base particles having conductivity and insulating fine particles covering the surfaces of the base particles;

a step of accommodating the composite particle in a hole of a particle accommodating member provided with a hole having a closed end face;

removing a part or all of the insulating fine particles located in the spherical cap region of the composite particle exposed from the hole;

a step of transferring the composite particles from which the insulating fine particles of the spherical cap region have been removed from the particle housing member onto a first adhesive layer so that the spherical cap region side is in contact with the first adhesive layer, and removing a part of the insulating fine particles of the composite particles by adhering the part to the closed end surface of the particle housing member, thereby providing insulating coated conductive particles on the first adhesive layer; and

and a step of bonding a second adhesive layer to the side of the first adhesive layer on which the insulating coated conductive particles are arranged.

10. A connection structure body is provided with:

a first circuit member having a bump electrode;

a second circuit member having a circuit electrode corresponding to the bump electrode; and

the insulation-coated conductive particle as claimed in any one of claims 1 to 4, which is interposed between and electrically connects the bump electrode and the circuit electrode.

11. A method for manufacturing a connection structure, comprising the steps of: the anisotropic conductive film according to any one of claims 5 to 8 or the anisotropic conductive film obtained by the method according to claim 9 is interposed between a first circuit member having a bump electrode and a second circuit member having a circuit electrode corresponding to the bump electrode, and the first circuit member and the second circuit member are thermocompression bonded.

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