JP2023086476A - Adhesive film for circuit connection, and circuit connection structure and method for manufacturing the same - Google Patents

Abstract

To provide an adhesive film for circuit connection which improves a conductive particle capturing rate between opposite electrodes of a circuit connection structure, and can reduce connection resistance of the circuit connection structure, even in the case of being mounted at low pressure.SOLUTION: An adhesive film 10A for circuit connection includes: a first adhesive layer 1 containing conductive particles 4, a cured product of a photocurable resin component and a first thermosetting resin component; and a second adhesive layer 2 which is provided on the first adhesive layer and contains a second thermosetting resin component. The photocurable resin component contains a radical-polymerizable compound and a photo-radical polymerization initiator. The photo-radical polymerization initiator contains a compound having an alkylphenone structure.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to a circuit-connecting adhesive film, a circuit-connecting structure, and a manufacturing method thereof.

2. Description of the Related Art Conventionally, liquid crystal display panels, organic EL panels, and the like have been used as various display means for televisions, PC monitors, mobile phones, smart phones, and the like. In such a display device, so-called COG (chip on glass) mounting, in which a driving IC is directly mounted on the glass substrate of the display panel, is adopted from the viewpoint of fine pitch, light weight and thinness.

In a liquid crystal display panel adopting the COG mounting method, for example, a semiconductor element such as a liquid crystal driving IC is connected on a transparent substrate (such as a glass substrate) having a plurality of transparent electrodes (such as ITO (indium tin oxide)). be. 2. Description of the Related Art As an adhesive material for connecting electrode terminals and transparent electrodes of a semiconductor element, a circuit-connecting adhesive film having conductive particles dispersed in an adhesive and having anisotropic conductivity is used. For example, when mounting a liquid crystal driving IC as a semiconductor element, the liquid crystal driving IC has a plurality of electrode terminals corresponding to transparent electrodes on its mounting surface, and an adhesive for circuit connection having anisotropic conductivity is used. By thermocompression bonding the liquid crystal driving IC onto the transparent substrate through the film, the electrode terminals and the transparent electrodes are connected to obtain a circuit connection structure.

In recent years, displays having curved surfaces (flexible displays) have been proposed. In such a flexible display, a flexible plastic substrate (such as a polyimide substrate) is used instead of a glass substrate as the substrate, so various electronic components such as a driving IC are also mounted on the plastic substrate. As such a mounting method, COP (chip on plastic) mounting using an adhesive film for circuit connection having anisotropic conductivity is being studied (see, for example, Patent Document 1).

JP 2016-054288 A

By the way, a substrate having a circuit electrode having a titanium layer as its outermost layer is used in a display panel. The connection resistance between circuits tends to decrease as the resin fluidity of the adhesive film increases. However, high resin fluidity means that conductive particles also flow easily at the same time. Poor connection may occur.

On the other hand, for example, the adhesive component of the circuit-connecting adhesive film may be cured by heat or light to reduce the fluidity of the conductive particles before the manufacturing process of the circuit-connecting adhesive film or circuit connection. being considered. However, in this case, the ability to remove the resin in the adhesive component is also lowered, which may increase the connection resistance of the circuit connection structure.

Resin expulsion can be tolerated in principle by mounting at high pressure. However, in recent years, organic EL panels have been becoming flexible displays, and the bottom surface of a plastic substrate (polyimide substrate, etc.) is usually coated with an adhesive layer such as a pressure-sensitive resin, PET (polyethylene terephthalate), PEN (polyethylene phthalate) and other films are arranged. The reduced elasticity of the substrate associated with these flexible displays may lead to the problem of circuit breakage due to the accumulation of stress in the circuit electrodes when the driver IC is mounted, causing cracks to occur in the outermost titanium layer. Therefore, in COP mounting, mounting at a low pressure (for example, an area-converted pressure of 0.1 to 50 MPa at the bump electrode) is desired.

Therefore, the present disclosure can improve the trapping rate of conductive particles between the opposing electrodes of the circuit connection structure and reduce the connection resistance of the circuit connection structure even when mounted at low pressure. The main object is to provide an adhesive film for circuit connection.

One aspect of the present disclosure relates to circuit connecting adhesive films. The adhesive film for circuit connection includes a first adhesive layer containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component, and provided on the first adhesive layer. and a second adhesive layer containing a second thermosetting resin component applied thereto. The photocurable resin component contains a radically polymerizable compound and a photoradical polymerization initiator. A radical photopolymerization initiator includes a compound having an alkylphenone structure. By including a compound having an alkylphenone structure in the photoradical polymerization initiator, it is possible to improve the trapping rate of conductive particles between the facing electrodes of the circuit connection structure and reduce the connection resistance of the circuit connection structure. becomes.

The thickness of the first adhesive layer may be 5.0 μm or less, and the ratio of the thickness of the first adhesive layer to the average particle size of the conductive particles may be 0.50 or more. By satisfying these conditions, the amount of resin between the opposed circuits can be reduced, and an increase in the connection resistance between the opposed circuits can be suppressed. Therefore, the adhesive film for circuit connection of the present disclosure can be mounted at a low pressure (for example, an area conversion pressure of 0.1 to 50 MPa at the bump electrode), and can be suitably used for COP mounting.

The monodispersity of the conductive particles in the circuit-connecting adhesive film may be 90% or more. In the present specification, the monodispersity ratio means the ratio of conductive particles present in a state (monodisperse state) separated from other conductive particles. When the monodispersity of the conductive particles is 90% or more, short circuits between adjacent circuits are less likely to occur, and a circuit connection structure with sufficiently high connection reliability tends to be easily obtained.

The first thermosetting resin component and the second thermosetting resin component may contain a cationic polymerizable compound and a thermal cationic polymerization initiator, and the photocurable resin component contains a radically polymerizable compound. You can At this time, the first thermosetting resin component and the second thermosetting resin component have cationic curability, and the photocurable resin component has radical curability. According to the studies of the present inventors, when such a combination of the first thermosetting resin component and the second thermosetting resin component and the photocurable resin component is such a combination, for example, all the curable resin components It tends to be superior in terms of connection resistance compared to the case where it has cationic curability. The inventors of the present disclosure speculate as follows as the reason why such an effect is produced. That is, if all the curable resin components have a cationic curable component, for example, in the first adhesive layer, cationic active species remain when the cured product of the photocurable resin component is formed. It is believed that this is because the curing reaction of the second thermosetting resin component in the second adhesive layer proceeds due to the cationic active species and the expulsion of the resin decreases. . Therefore, if the photocurable resin component has radical curability, cationic active species are not generated when the cured product of the photocurable resin component is formed. It is expected that the progress of the curing reaction of the thermosetting resin component can be suppressed, the deterioration of the expulsion of the resin can be suppressed, and the connection resistance can be reduced.

The cationic polymerizable compound may be at least one selected from the group consisting of oxetane compounds and alicyclic epoxy compounds. The thermal cationic polymerization initiator may be a salt compound having an anion containing boron as a constituent element.

The adhesive film for circuit connection further comprises a third adhesive layer containing a third thermosetting resin component provided on the opposite side of the first adhesive layer to the second adhesive layer. may be The third thermosetting resin component may contain a cationic polymerizable compound and a thermal cationic polymerization initiator.

Another aspect of the present disclosure relates to a method of manufacturing a circuit connection structure. The method for manufacturing the circuit connection structure includes interposing the circuit connection adhesive film between a first circuit member having a first electrode and a second circuit member having a second electrode, Thermocompression bonding the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

Another aspect of the present disclosure relates to circuit connection structures. The circuit connection structure is arranged between a first circuit member having a first electrode, a second circuit member having a second electrode, and the first circuit member and the second circuit member, and a circuit connection portion electrically connecting the first electrode and the second electrode to each other. The circuit connecting part contains the cured body of the circuit connecting adhesive film.

According to the present disclosure, even when mounted at a low pressure, it is possible to improve the capture rate of conductive particles between the opposing electrodes of the circuit connection structure and reduce the connection resistance of the circuit connection structure. A circuit-connecting adhesive film is disclosed. Such an adhesive film for circuit connection can be suitably used for COP mounting. Further, according to the present disclosure, a circuit connection structure using such an adhesive film for circuit connection and a method for manufacturing the same are disclosed.

FIG. 1 is a schematic cross-sectional view showing one embodiment of an adhesive film for circuit connection. FIG. 2 is a schematic cross-sectional view showing another embodiment of an adhesive film for circuit connection. FIG. 3 is a schematic cross-sectional view of a substrate used for manufacturing the circuit-connecting adhesive film of FIG. FIG. 4 is a diagram showing a state in which conductive particles are arranged in the recesses of the base shown in FIG. 5(a) and 5(b) are schematic cross-sectional views showing one step of the method for producing the circuit-connecting adhesive film of FIG. 6(a) and 6(b) are schematic cross-sectional views showing one step of the method for producing the circuit-connecting adhesive film of FIG. FIG. 7 is a schematic cross-sectional view showing one embodiment of the circuit connection structure. 8A and 8B are schematic cross-sectional views showing an embodiment of a method for manufacturing a circuit connection structure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and overlapping descriptions are omitted. Note that the present disclosure is not limited to the following embodiments.

In this specification, a numerical range indicated using "to" indicates a range including the numerical values before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or lower limit value of the numerical range at one step may be replaced with the upper limit value or lower limit value of the numerical range at another step. Moreover, in the numerical ranges described in this specification, the upper and lower limits of the numerical ranges may be replaced with the values shown in the examples. Moreover, the upper limit value and the lower limit value described individually can be combined arbitrarily. In the notation of a numerical range “A to B”, both numerical values A and B are included in the numerical range as lower and upper limits, respectively. In this specification, for example, the description “10 or more” means “10” and “a numerical value exceeding 10”, and this applies even when the numerical values are different. Further, for example, the description "10 or less" means "10" and "a numerical value less than 10", and this applies even when the numerical values are different. Moreover, in this specification, "(meth)acrylate" means at least one of acrylate and methacrylate corresponding thereto. The same applies to other similar expressions such as "(meth)acryloyl" and "(meth)acrylic acid". Moreover, "A or B" may include either one of A and B, or may include both. Materials exemplified below may be used singly or in combination of two or more unless otherwise specified. The content of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition.

[Adhesive film for circuit connection]
FIG. 1 is a schematic cross-sectional view showing one embodiment of the circuit-connecting adhesive film, and is a view schematically showing a longitudinal cross-section of the circuit-connecting adhesive film. The circuit-connecting adhesive film 10A shown in FIG. 1 contains a plurality of conductive particles 4, and an adhesive component 3 containing a cured product of a photocurable resin component and a (first) thermosetting resin component. It comprises a first adhesive layer 1 and a second adhesive layer 2 containing a (second) thermosetting resin component provided on the first adhesive layer 1 . As used herein, the term "longitudinal section" means a section (section in the thickness direction) perpendicular to the main surface (for example, the circuit-connecting adhesive film 10A). Also, the first thermosetting resin component and the second thermosetting resin component mean the thermosetting resin components contained in the first adhesive layer and the second adhesive layer, respectively. The circuit-connecting adhesive film 10A includes a first region containing a plurality of conductive particles 4, and an adhesive component 3 containing a cured photocurable resin component and a (first) thermosetting resin component. , and a second region containing a (second) thermosetting resin component provided adjacent to the first region.

At least some of the plurality of conductive particles 4 may be arranged in the horizontal direction in the longitudinal section of the circuit-connecting adhesive film 10A with adjacent conductive particles separated from each other. In other words, the circuit-connecting adhesive film 10A, in its vertical cross-section, has a central region 10a in which the conductive particles 4 are arranged in a horizontal direction separated from the adjacent conductive particles, and the conductive particles 4 are present. It may be configured by surface side regions 10b and 10c that do not. Here, the "horizontal direction" means a direction parallel to the main surface of the circuit-connecting adhesive film (horizontal direction in FIG. 1). In FIG. 1, part of the conductive particles 4 are exposed from the surface of the first adhesive layer 1 (for example, protrude toward the second adhesive layer 2), but the conductive particles 4 are The entire conductive particles 4 may be embedded in the first adhesive layer 1 so as not to be exposed from the surface of the adhesive layer 1 .

Conductive particles 4 may be dispersed in the first adhesive layer 1 of the circuit-connecting adhesive film 10A. Therefore, the circuit-connecting adhesive film 10A can be a circuit-connecting adhesive film having anisotropic conductivity (anisotropically conductive adhesive film). The circuit-connecting adhesive film 10A is interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, so that the first circuit member and the second circuit It may be used to thermocompress members to electrically connect the first electrode and the second electrode to each other. The term "anisotropically conductive" means to conduct in the pressurized direction and maintain insulation in the non-pressurized direction.

<First adhesive layer>
The first adhesive layer 1 is composed of conductive particles 4 (hereinafter sometimes referred to as "(A) component") and a photocurable resin component (hereinafter sometimes referred to as "(B) component"). and a thermosetting resin component (hereinafter sometimes referred to as "(C) component"). The cured product of component (B) may be a cured product obtained by completely curing component (B) or a cured product obtained by partially curing component (B). Component (C) is a component that can flow when connected, and is, for example, an uncured curable component (eg, resin component). Components other than the conductive particles 4 that constitute the first adhesive layer 1 are, for example, non-conductive components (eg, insulating resin components).

[(A) component: conductive particles]
The component (A) is not particularly limited as long as it is conductive particles, and includes metal particles composed of metals such as Au, Ag, Pd, Ni, Cu, solder, and conductive carbon composed of conductive carbon. It may be particles or the like. Component (A) is a coated conductive particle comprising a nucleus containing non-conductive glass, ceramic, plastic (such as polystyrene), etc., and a coating layer containing the metal or the conductive carbon and covering the nucleus, good too. As the component (A), one type of various conductive particles may be used alone, or a plurality thereof may be used in combination. Among these, the component (A) is preferably formed of a coated conductive particle comprising a core containing plastic and a coating layer containing metal or conductive carbon and covering the core, or a heat-fusible metal. metal particles.

When the component (A) is coated conductive particles, the cured product of the thermosetting resin component can be easily deformed by heating or pressing. ) can increase the contact area with the component and further improve the electrical conductivity between the electrodes.

When the component (A) is metal particles made of a heat-fusible metal, the connection between the electrodes tends to be stronger. This tendency is remarkable when solder particles are used as the component (A).

The solder particles may contain at least one selected from the group consisting of tin, tin alloys, indium, and indium alloys from the viewpoint of achieving both bonding strength and low melting point. In addition, from the viewpoint of obtaining higher reliability during high-temperature and high-humidity tests and thermal shock tests, the solder particles are selected from In--Bi alloys, In--Sn alloys, In--Sn--Ag alloys, Sn--Au alloys, Sn-- At least one selected from the group consisting of Bi alloys, Sn--Bi--Ag alloys, Sn--Ag--Cu alloys and Sn--Cu alloys may be included.

Component (A) is an insulation-coated conductive particle comprising the metal particles, the conductive carbon particles, or the coated conductive particles, and an insulating material such as a resin, and an insulating layer covering the surface of the particles. good too. When the component (A) is an insulating coating conductive particle, even if the content of the component (A) is large, the surface of the particle is provided with an insulating layer, so the short circuit due to the contact between the components (A) The occurrence can be suppressed, and the insulation between adjacent electrode circuits can be improved.

The maximum particle size of component (A) must be smaller than the minimum distance between electrodes (the shortest distance between adjacent electrodes). The maximum particle size of component (A) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more from the viewpoint of excellent dispersibility and conductivity. The maximum particle size of component (A) is 30.0 μm or less, 25.0 μm or less, 20.0 μm or less, 15.0 μm or less, 10.0 μm or less, or 5.0 μm or less from the viewpoint of excellent dispersibility and conductivity. can be In this specification, 300 pieces (pcs) of any component (A) in the first adhesive layer are measured for particle size by observation using a scanning electron microscope (SEM), and the largest value obtained is the maximum particle size of the component (A). When the component (A) is not spherical, such as when the component (A) has projections, the particle size of the component (A) is the diameter of a circle circumscribing the conductive particles in the SEM image.

The average particle diameter of component (A) may be 1.0 μm or more, 2.0 μm or more, 2.5 μm or more, or 3.0 μm or more from the viewpoint of excellent dispersibility and conductivity. The average particle diameter of component (A) may be 20.0 µm or less, 10.0 µm or less, 7.0 µm or less, or 5.0 µm or less from the viewpoint of excellent dispersibility and conductivity. In this specification, the particle size is measured by observation using a scanning electron microscope (SEM) for any 300 (pcs) of component (A) in the first adhesive layer, and the obtained particle size Let the average value be the average particle size.

Component (A) is preferably dispersed uniformly in the first adhesive layer 1 . From the viewpoint of obtaining a stable connection resistance, the particle density of the component (A) in the circuit connection adhesive film 10A is 100 particles/mm ² or more, 1000 particles/mm ² or more, 3000 particles/mm ² or more, 5000 particles. / ^mm2 or more, 7000/ ^mm2 or more, 10000/mm2 or ^more , or 12000/mm2 ^or more. The particle density of the component (A) in the circuit-connecting adhesive film 10A is 100,000 particles/mm ² or less, 70,000 particles/mm ² or less, or 50,000 particles/mm ^{2 or} less, from the viewpoint of improving the insulation between adjacent electrodes. , 30,000/mm ² or less, or 20,000/mm ² or less.

The monodispersity of the component (A) in the circuit-connecting adhesive film 10A may be 90% or more. When the monodispersity of component (A) is within this range, short circuits between adjacent circuits are less likely to occur, and a circuit connection structure with sufficiently high connection reliability tends to be easily obtained. The monodispersity of component (A) may be 92% or higher, 94% or higher, 96% or higher, 97% or higher, 98% or higher, or 99% or higher. The upper limit of monodispersity can be 100%. For example, the monodispersity is obtained by observing the circuit-connecting adhesive film 10A from the first adhesive layer side at a magnification of 200 using a metallurgical microscope, and measuring the component (A) in the circuit-connecting adhesive film 10A. The number can be measured and obtained according to the following formula.
Monodisperse rate (%) = (Number of conductive particles in a monodispersed state (separated from other conductive particles) in 2500 µm ² / Number of conductive particles in 2500 µm ² ) x 100

The content of component (A) is 1% by mass or more, 5% by mass or more, or 10% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of being able to further improve the conductivity. It's okay. The content of component (A) may be 60% by mass or less, 50% by mass or less, or 40% by mass or less based on the total mass of the first adhesive layer, from the viewpoint of easily suppressing short circuits. When the content of component (A) is within the above range, the effects of the present disclosure tend to be remarkably exhibited. The content of component (A) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[(B) component: photocurable resin component]
The component (B) is not particularly limited as long as it is a resin component that is cured by light irradiation, but when the component (C) is a cationic curable resin component, the component (B) is used from the viewpoint of better connection resistance. , a resin component having radical curability. Component (B) includes, for example, a radically polymerizable compound (hereinafter sometimes referred to as "(B1) component") and a photoradical polymerization initiator (hereinafter sometimes referred to as "(B2) component"). You can stay. The (B) component can be a component consisting of the (B1) component and the (B2) component.

(B1) Component: Radically Polymerizable Compound The (B1) component is a compound polymerized by radicals generated from the (B2) component by irradiation with light (eg, ultraviolet light). The component (B1) may be either a monomer or a polymer (or oligomer) obtained by polymerizing one or more monomers. (B1) component may be used individually by 1 type, and may be used in combination of plurality.

The (B1) component is a compound having a radically polymerizable group that reacts with radicals. Examples of radically polymerizable groups include (meth)acryloyl groups, vinyl groups, allyl groups, styryl groups, alkenyl groups, alkenylene groups, maleimide groups and the like. The number of radically polymerizable groups (number of functional groups) of the component (B1) is 2 or more from the viewpoint that the desired melt viscosity is easily obtained after polymerization, the effect of reducing the connection resistance is further improved, and the connection reliability is excellent. from the viewpoint of suppressing curing shrinkage during polymerization, it may be 10 or less. In addition to the compound having the number of radically polymerizable groups within the above range, a compound having the number of radically polymerizable groups outside the above range may also be used in order to balance the crosslink density and cure shrinkage. good.

The (B1) component may contain, for example, a polyfunctional (difunctional or higher) (meth)acrylate from the viewpoint of suppressing the flow of the conductive particles. The polyfunctional (bifunctional or higher) (meth)acrylate may be a bifunctional (meth)acrylate, and the bifunctional (meth)acrylate may be a bifunctional aromatic (meth)acrylate.

Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate. ) acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated polypropylene glycol Di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1 , 10-decanediol di(meth)acrylate, glycerine di(meth)acrylate, tricyclodecanedimethanol (meth)acrylate, ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate and other aliphatic ( meth)acrylate; ethoxylated bisphenol A type di(meth)acrylate, propoxylated bisphenol A type di(meth)acrylate, ethoxylated propoxylated bisphenol A type di(meth)acrylate, ethoxylated bisphenol F type di(meth)acrylate, Propoxylated bisphenol F type di(meth)acrylate, ethoxylated propoxylated bisphenol F type di(meth)acrylate, ethoxylated fluorene type di(meth)acrylate, propoxylated fluorene type di(meth)acrylate, ethoxylated propoxylated fluorene type Aromatic (meth)acrylates such as di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated tri(meth)acrylate Methylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated propoxylated pentaerythritol tri(meth)acrylate, pentaerythritol Tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexa(meth)acrylate ) aliphatic (meth)acrylates such as acrylates; aromatic epoxy (meth)acrylates such as bisphenol-type epoxy (meth)acrylates, phenol novolac-type epoxy (meth)acrylates, and cresol novolak-type epoxy (meth)acrylates.

The content of the polyfunctional (difunctional or higher) (meth)acrylate is, for example, 40 to 100 based on the total mass of the component (B1), from the viewpoint of achieving both the effect of reducing connection resistance and suppressing particle flow. % by weight, 50-100% by weight, or 60-100% by weight.

The (B1) component may further contain a monofunctional (meth)acrylate in addition to the polyfunctional (bifunctional or higher) (meth)acrylate. Monofunctional (meth)acrylates include, for example, (meth)acrylic acid; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, butoxyethyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octylheptyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate acrylates 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxy Aliphatic (meth)acrylates such as polyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropylene glycol (meth)acrylate, mono(2-(meth)acryloyloxyethyl)succinate; benzyl (meth)acrylate , phenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthyl (meth)acrylate, phenoxyethyl (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, o - phenylphenoxyethyl (meth)acrylate, 1-naphthoxyethyl (meth)acrylate, 2-naphthoxyethyl (meth)acrylate, phenoxypolyethyleneglycol (meth)acrylate, nonylphenoxypolyethyleneglycol (meth)acrylate, phenoxypolypropyleneglycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl (meth)acrylate, 2- Aromatic (meth)acrylates such as hydroxy-3-(2-naphthoxy)propyl (meth)acrylate; (meth)acrylates having an epoxy group such as glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate and (meth)acrylates having an alicyclic epoxy group such as (3-ethyloxetan-3-yl)methyl (meth)acrylate and the like, and (meth)acrylates having an oxetanyl group such as (meth)acrylate.

The content of monofunctional (meth)acrylate may be, for example, 0 to 60% by mass, 0 to 50% by mass, or 0 to 40% by mass based on the total mass of component (B1).

The cured product of component (B) may have, for example, a polymerizable group that reacts with something other than radicals. Polymerizable groups that react by means other than radicals may be, for example, cationically polymerizable groups that react by means of cations. Examples of cationic polymerizable groups include epoxy groups such as glycidyl groups, alicyclic epoxy groups such as epoxycyclohexylmethyl groups, and oxetanyl groups such as ethyloxetanylmethyl groups. The cured product of the component (B) having a polymerizable group that reacts by means other than radicals is, for example, a (meth)acrylate having an epoxy group, a (meth)acrylate having an alicyclic epoxy group, or a (meth)acrylate having an oxetanyl group. It can be introduced by using a (meth)acrylate having a polymerizable group that reacts by means other than radicals such as (B) as the component (B). (B1) Mass ratio of (meth) acrylate having a polymerizable group that reacts with a non-radical to the total mass of the component (mass of (meth) acrylate having a polymerizable group that reacts with a non-radical (amount charged)/(B1) The total mass (amount charged) of the components may be, for example, 0 to 0.7, 0 to 0.5, or 0 to 0.3 from the viewpoint of improving reliability.

The (B1) component may contain other radically polymerizable compounds in addition to polyfunctional (difunctional or higher) and monofunctional (meth)acrylates. Other radically polymerizable compounds include, for example, maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, nadimide derivatives and the like. The content of other radically polymerizable compounds may be, for example, 0 to 40% by mass based on the total mass of component (B1).

Component (B2): Photoradical polymerization initiator Component (B2) includes light having a wavelength within the range of 150 to 750 nm, preferably light having a wavelength within the range of 254 to 405 nm, more preferably light having a wavelength of 365 nm. It is a compound that generates radicals by irradiation with light (for example, ultraviolet light).

The (B2) component contains a compound having an alkylphenone structure. Examples of compounds having an alkylphenone structure include compounds having an α-hydroxyalkylphenone structure and compounds having an α-aminoalkylphenone structure.

Specific examples of compounds having an α-hydroxyalkylphenone structure include 1-hydroxycyclohexyl-phenylketone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-[4-(2-hydroxyethoxyl)-phenyl ]-2-hydroxy-methylpropanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one and the like. The compounds having an α-hydroxyalkylphenone structure may be used singly or in combination of two or more. A compound having an α-hydroxyalkylphenone structure may be used in combination with a compound having an α-aminoalkylphenone structure described below.

Commercially available compounds having an α-hydroxyalkylphenone structure include Omnirad 184, Omnirad 1173, Omnirad 2959, and Omnirad 127 (trade names, all manufactured by IGM Resins).

Specific examples of compounds having an α-aminoalkylphenone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1 -morpholinophenyl)-butanone-1 and the like. The compounds having an α-aminoalkylphenone structure may be used singly or in combination of two or more. A compound having an α-aminoalkylphenone structure may be used in combination with the above compound having an α-hydroxyalkylphenone structure.

Commercially available compounds having an α-aminoalkylphenone structure include Omnirad 907 and Omnirad 369 (trade names, both manufactured by IGM Resins).

The (B2) component may or may not contain a compound having another structure in addition to the compound having an alkylphenone structure. Examples of compounds having other structures include compounds having structures such as oxime ester structure, bisimidazole structure, acridine structure, aminobenzophenone structure, N-phenylglycine structure, acylphosphine oxide structure, and benzyldimethylketal structure. be done. The (B2) component preferably does not contain compounds having other structures.

The content of component (B2) is, for example, 0.1 to 10 parts by mass, 0.3 to 7 parts by mass, or 0 with respect to 100 parts by mass of component (B1) from the viewpoint of suppressing the flow of conductive particles. .5 to 5 parts by mass.

From the viewpoint of suppressing the flow of the conductive particles, the content of the cured product of component (B) is 1% by mass or more, 5% by mass or more, or 10% by mass or more based on the total mass of the first adhesive layer. can be The content of the cured product of component (B) is 50% by mass or less, 40% by mass or less, or 30% by mass, based on the total mass of the first adhesive layer, from the viewpoint of expressing low resistance in low-pressure mounting. may be: When the content of the cured product of component (B) is within the above range, the effects of the present disclosure tend to be remarkably exhibited. The content of component (B) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[(C) component: thermosetting resin component]
Component (C) is not particularly limited as long as it is a resin component that is cured by heat. , a cationic curable resin component. Component (C) includes, for example, a cationic polymerizable compound (hereinafter sometimes referred to as "(C1) component") and a thermal cationic polymerization initiator (hereinafter sometimes referred to as "(C2) component"). You can stay. Component (C) may be a component consisting of component (C1) and component (C2). The first thermosetting resin component, the second thermosetting resin component, and the third thermosetting resin component are the first adhesive layer, the second adhesive layer, and the third thermosetting resin component, respectively. It means a thermosetting resin component contained in the adhesive layer, and components contained in the first thermosetting resin component, the second thermosetting resin component, and the third thermosetting resin component (for example, (C1) component, (C2) component, etc.) and contents may be the same or different.

Component (C1): Cationic polymerizable compound Component (C1) is a compound that crosslinks by reacting with component (C2) by heat. The (C1) component means a compound that does not have a radically polymerizable group that reacts with radicals, and the (C1) component is not included in the (B1) component. (C1) Component includes, for example, compounds having a cyclic ether group such as oxetane compounds and epoxy compounds. (C1) component may be used individually by 1 type, and may be used in combination of plurality. The component (C1) may contain, for example, at least one selected from the group consisting of an oxetane compound and an alicyclic epoxy compound, from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability. . The component (C1) preferably contains both at least one oxetane compound and at least one alicyclic epoxy compound from the viewpoint of easily obtaining a desired melt viscosity.

As the oxetane compound as the component (C1), any compound having an oxetanyl group and not having a radically polymerizable group can be used without particular limitation. Examples of commercially available oxetane compounds include ETERNACOLL OXBP (trade name, 4,4′-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl, manufactured by Ube Industries, Ltd.), OXSQ, OXT-121, OXT-221, OXT-101, OXT-212 (trade name, manufactured by Toagosei Co., Ltd.) and the like. One of these compounds may be used alone, or two or more of them may be used in combination.

The alicyclic epoxy compound as the component (C1) is not particularly limited as long as it has an alicyclic epoxy group (for example, an epoxycyclohexyl group) and does not have a radically polymerizable group. Examples of commercially available alicyclic epoxy compounds include EHPE3150, EHPE3150CE, Celoxide 8010, Celoxide 2021P, Celoxide 2081 (trade name, manufactured by Daicel Corporation). One of these compounds may be used alone, or two or more of them may be used in combination.

Component (C2): Thermal Cationic Polymerization Initiator Component (C2) is a thermal polymerization initiator that initiates polymerization by generating an acid or the like upon heating. The (C2) component may be a salt compound composed of a cation and an anion. Component (C2) is, for example, BF ₄ ⁻ , BR ₄ ⁻ (R represents a phenyl group substituted with two or more fluorine atoms or two or more trifluoromethyl groups), PF ₆ ⁻ , SbF ₆ ⁻ and onium salts such as sulfonium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, anilinium salts, and pyridium salts having anions such as AsF ₆ ^— . These may be used individually by 1 type, and may be used in combination of plurality.

From the viewpoint of storage stability, the component (C2) is, for example, an anion containing boron as a constituent element, that is, BF ₄ ⁻ or BR ₄ ⁻ (R is 2 or more fluorine atoms or 2 or more trifluoromethyl groups). represents a substituted phenyl group). The anion containing boron as a constituent element may be BR ₄ ^— , more specifically tetrakis(pentafluorophenyl)borate.

The onium salt as component (C2) may be, for example, anilinium salt, since it has resistance to substances that can inhibit cationic curing. Examples of anilinium salt compounds include N,N-dialkylanilinium salts such as N,N-dimethylanilinium salts and N,N-diethylanilinium salts.

The (C2) component may be an anilinium salt having an anion containing boron as a constituent element. Commercially available products of such salt compounds include, for example, CXC-1821 (trade name, manufactured by King Industries).

From the viewpoint of securing the formability and curability of the first adhesive layer, the content of component (C2) is, for example, 0.1 to 20 parts by mass, 1 18 parts by weight, 3 to 15 parts by weight, or 5 to 12 parts by weight.

From the viewpoint of ensuring the curability of the first adhesive layer, the content of component (C) is 5% by mass or more, 10% by mass or more, and 15% by mass, based on the total mass of the first adhesive layer. or more, or 20% by mass or more. From the viewpoint of ensuring the formability of the first adhesive layer, the content of component (C) is 70% by mass or less, 60% by mass or less, and 50% by mass, based on the total mass of the first adhesive layer. or less, or 40% by mass or less. When the content of component (C) is within the above range, the effects of the present disclosure tend to be remarkably exhibited. The content of component (C) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[Other ingredients]
The first adhesive layer 1 may further contain other components in addition to the (A) component, the cured product of the (B) component, and the (C) component. Other components include, for example, a thermoplastic resin (hereinafter sometimes referred to as "(D) component"), a coupling agent (hereinafter sometimes referred to as "(E) component"), a filler (hereinafter sometimes referred to as "(E) component"), , and may be referred to as “(F) component”).

Component (D) includes, for example, phenoxy resins, polyester resins, polyamide resins, polyurethane resins, polyester urethane resins, acrylic rubbers, epoxy resins (solid at 25°C), and the like. These may be used individually by 1 type, and may be used in combination of plurality. A composition layer (further the first adhesive layer 1) is formed from the composition containing the components (A), (B), and (C) by further containing the component (D). can be easily formed. Among these, the (D) component may be, for example, a phenoxy resin. The content of component (D) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, and 70% by mass or less, or 50% by mass, based on the total mass of the first adhesive layer. or less, or 30% by mass or less. The content of component (D) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

Examples of component (E) include silane coupling agents having organic functional groups such as (meth)acryloyl groups, mercapto groups, amino groups, imidazole groups and epoxy groups, silane compounds such as tetraalkoxysilanes, and tetraalkoxytitanate derivatives. , polydialkyl titanate derivatives and the like. These may be used individually by 1 type, and may be used in combination of plurality. By including the component (E) in the first adhesive layer 1, the adhesiveness can be further improved. The (E) component may be, for example, a silane coupling agent. The content of component (E) may be 0.1 to 10% by mass based on the total mass of the first adhesive layer. The content of component (E) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

Component (F) includes, for example, non-conductive fillers (eg, non-conductive particles). (F) Component may be either an inorganic filler or an organic filler. Examples of inorganic fillers include metal oxide fine particles such as silica fine particles, alumina fine particles, silica-alumina fine particles, titania fine particles and zirconia fine particles; and inorganic fine particles such as metal nitride fine particles. Examples of the organic filler include organic fine particles such as silicone fine particles, methacrylate/butadiene/styrene fine particles, acryl/silicone fine particles, polyamide fine particles, and polyimide fine particles. These may be used individually by 1 type, and may be used in combination of plurality. The (F) component may be silica fine particles, for example. The content of component (F) may be 0.1 to 10% by mass based on the total mass of the first adhesive layer. The content of component (F) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[Other additives]
The first adhesive layer 1 may further contain other additives such as softeners, accelerators, antidegradants, colorants, flame retardants, and thixotropic agents. The content of other additives may be, for example, 0.1 to 10% by mass based on the total mass of the first adhesive layer. The content of other additives in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

The thickness d1 of the first adhesive layer 1 may be, for example, 30.0 μm or less, 20.0 μm or less, 15.0 μm or less, 10.0 μm or less, 8.0 μm or less, 5.0 μm or less, 4 .5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, or 2.5 μm or less. When the thickness d1 of the first adhesive layer 1 is 30.0 μm or less, the amount of resin between the opposing circuits is reduced, and an increase in the connection resistance between the opposing circuits can be suppressed. Such a tendency is more pronounced when the thickness d1 of the first adhesive layer 1 is 5.0 μm or less. The thickness d1 of the first adhesive layer 1 may be, for example, 0.1 μm or more or 0.7 μm or more. In addition, as shown in FIG. 1, when a part of the conductive particles 4 is exposed from the surface of the first adhesive layer 1 (for example, protrudes toward the second adhesive layer 2), the first The first adhesive layer 1 and the second adhesive layer 2 located in the spaced part between the adjacent conductive particles 4, 4 are separated from the surface 1a of the adhesive layer 1 opposite to the second adhesive layer 2 side. is the thickness of the first adhesive layer 1, and the exposed portion of the conductive particles 4 is included in the thickness of the first adhesive layer 1. can't The length of the exposed portion of the conductive particles 4 may be, for example, 0.1 μm or more and 5.0 μm or less.

The thickness d1 of the first adhesive layer 1 can be determined, for example, by the method described in Examples. Specifically, the adhesive film for circuit connection is sandwiched between two sheets of glass (thickness: about 1 mm), and 100 g of bisphenol A type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and a curing agent (trade name: JER811). Name: Epomount Curing Agent, manufactured by Refinetech Co., Ltd.) After casting with a resin composition consisting of 10 g, the cross section is polished using a polishing machine, and a scanning electron microscope (SEM, product name: SU-8020, stock manufactured by Hitachi High-Tech Science). Such an operation may be performed multiple times and the average value thereof may be used as the thickness d1 of the first adhesive layer 1 .

The ratio of the thickness of the first adhesive layer 1 to the average particle size of the conductive particles 4 (thickness of the first adhesive layer 1/average particle size of the conductive particles 4) may be 0.50 or more. , for example, 0.55 or more, or 0.60 or more. When the ratio is 0.50 or more, the amount of resin between the opposing circuits is reduced, and it is possible to suppress an increase in the connection resistance between the opposing circuits. The ratio may be, for example, 2.00 or less, 1.50 or less, 1.20 or less, 1.00 or less, or 0.80 or less.

<Second adhesive layer>
The second adhesive layer 2 may be, for example, an insulating adhesive layer composed of a non-conductive component (insulating resin component). The second adhesive layer 2 contains at least component (C).

The (C1) component and (C2) component used in the (C) component (that is, the second thermosetting resin component) in the second adhesive layer 2 are (C) in the first adhesive layer 1 Since it is the same as the components (C1) and (C2) used in the component (that is, the first thermosetting resin component), detailed description is omitted here. The second thermoset resin component may be the same as or different from the first thermoset resin component.

From the viewpoint of maintaining reliability, the content of component (C) is 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more based on the total mass of the second adhesive layer. can be The content of component (C) is 80% by mass or less, 70% by mass or less, based on the total mass of the second adhesive layer, from the viewpoint of preventing resin seepage problems in the reel, which is one mode of the supply form. , 60% by mass or less, or 50% by mass or less.

The second adhesive layer 2 may further contain other components and other additives in the first adhesive layer 1 . Preferred aspects of other components and other additives are the same as those of the first adhesive layer 1 .

The content of component (D) may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and 60% by mass or less, or 40% by mass, based on the total mass of the second adhesive layer. or less, or 20% by mass or less.

The content of component (E) may be 0.1 to 10% by mass based on the total mass of the second adhesive layer.

The content of component (F) may be 1% by mass or more, 10% by mass or more, or 30% by mass or more, and 90% by mass or less, or 70% by mass, based on the total mass of the second adhesive layer. or less, or 50% by mass or less.

The content of other additives may be, for example, 0.1 to 10% by mass based on the total mass of the second adhesive layer.

The thickness d2 of the second adhesive layer 2 may be appropriately set according to the height of the electrodes of the circuit member to be adhered. The thickness d2 of the second adhesive layer 2 is 5.0 μm or more or 7 μm or more from the viewpoint of sufficiently filling the space between the electrodes to seal the electrodes and obtaining better connection reliability. 0 μm or more, and may be 30.0 μm or less, 20.0 μm or less, 15.0 μm or less, or 13.0 μm or less. In addition, when a part of the conductive particles 4 is exposed from the surface of the first adhesive layer 1 (for example, protruding to the second adhesive layer 2 side), the first The distance from the surface 2a opposite to the adhesive layer 1 side to the boundary S between the first adhesive layer 1 and the second adhesive layer 2 located in the spaced portion between the adjacent conductive particles 4, 4 ( The distance indicated by d2 in FIG. 1) is the thickness of the second adhesive layer 2 .

The thickness d2 of the second adhesive layer 2 can be obtained, for example, in the same manner as the method for measuring the thickness d1 of the first adhesive layer 1 described above.

The thickness of the circuit-connecting adhesive film 10A (total thickness of all layers constituting the circuit-connecting adhesive film 10A; in FIG. 1, the thickness d1 of the first adhesive layer 1 and the thickness of the second The total thickness d2 of the adhesive layer 2) may be, for example, 5.0 μm or more or 8.0 μm or more, 60.0 μm or less, 40.0 μm or less, 30.0 μm or less, or 20.0 μm or less. It's okay.

The circuit-connecting adhesive film 10A is an adhesive film used for circuit connection. The circuit-connecting adhesive film 10A may or may not have anisotropic conductivity. That is, the circuit-connecting adhesive film may be an anisotropically conductive adhesive film or a non-anisotropically conductive (for example, isotropically conductive) adhesive film. The circuit-connecting adhesive film 10A includes a first circuit member having a first electrode (the surface on which the first electrode is provided) and a second circuit member having the second electrode (the The surface on which the second electrode is provided), and the first circuit member and the second circuit member are thermocompression bonded (the first circuit member, the circuit connection adhesive film 10A, and The laminate including the second circuit member is heated while being pressed in the thickness direction of the laminate), and the first electrode and the second electrode are connected (via the conductive particles (or the melted and solidified conductive particles) ) may be used to electrically connect to each other.

According to the circuit-connecting adhesive film 10A, the thermosetting resin component secures the expulsion of the resin at the time of connection, while the cured product of the photo-curable resin component suppresses the fluidity of the conductive particles at the time of connection, thereby achieving connection. It is possible to improve the trapping rate of the conductive particles between the electrodes. Therefore, according to the circuit connection adhesive film 10A, it is possible to reduce the connection resistance of the circuit connection structure.

Although the circuit connection adhesive film of the present embodiment has been described above, the present disclosure is not limited to the above embodiment.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the circuit-connecting adhesive film, and schematically shows a longitudinal cross-section of the circuit-connecting adhesive film. The circuit-connecting adhesive film may be composed of, for example, two layers of a first adhesive layer and a second adhesive layer. It may be composed of three or more layers including two layers. The circuit-connecting adhesive film is provided on the opposite side of the first adhesive layer to the second adhesive layer, for example, like the circuit-connecting adhesive film 10B shown in FIG. 3) A third adhesive layer 5 containing a thermosetting resin component may be further provided. The circuit-connecting adhesive film 10B further includes a third region containing a (third) thermosetting resin component, provided adjacent to the first region on the opposite side of the second region. It can also be said that

The third adhesive layer 5 contains at least component (C). The (C1) component and (C2) component used in the (C) component (that is, the third thermosetting resin component) in the third adhesive layer are the (C) component in the first adhesive layer 1 (that is, the first thermosetting resin component), the detailed description is omitted here because it is the same as the components (C1) and (C2) used in the first thermosetting resin component. The third thermoset resin component may be the same as or different from the first thermoset resin component. The third thermoset resin component may be the same as or different from the second thermoset resin component.

The content of component (C) is 5% by mass or more, 10% by mass or more, or 15% by mass or more, based on the total mass of the third adhesive layer, from the viewpoint of imparting good transferability and peeling resistance. , or 20% by mass or more. The content of component (C) is 70% by mass or less, based on the total mass of the third adhesive layer, from the viewpoint of imparting good half-cutting properties and anti-blocking properties (suppression of resin exudation from the reel). It may be 60% by mass or less, 50% by mass or less, or 40% by mass or less.

The third adhesive layer 5 may further contain other components and other additives in the first adhesive layer 1 . Preferred aspects of other components and other additives are the same as those of the first adhesive layer 1 .

The content of component (D) may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and 80% by mass or less, or 70% by mass, based on the total mass of the third adhesive layer. or less, or 60% by mass or less.

The content of component (E) may be 0.1 to 10% by mass based on the total mass of the third adhesive layer.

The content of component (F) may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and 50% by mass or less, or 40% by mass, based on the total mass of the third adhesive layer. or less, or 30% by mass or less.

The content of other additives may be, for example, 0.1 to 10% by mass based on the total mass of the third adhesive layer.

The thickness d3 of the third adhesive layer 5 may be appropriately set according to the height of the electrodes of the circuit member to be adhered. The thickness d3 of the third adhesive layer 5 is 0.2 μm or more or 0.2 μm or more from the viewpoint of sufficiently filling the space between the electrodes to seal the electrodes and obtaining better connection reliability. .5 μm or more, and may be 5.0 μm or less, or 2.5 μm or less. The thickness d3 of the third adhesive layer 5 is measured from the surface 5a of the third adhesive layer 5 opposite to the first adhesive layer 1 to the second adhesion It is the distance to the surface 1a on the side opposite to the agent layer 2 side (the distance indicated by d3 in FIG. 2).

The thickness d3 of the third adhesive layer 5 can be obtained, for example, in the same manner as the method for measuring the thickness d1 of the first adhesive layer 1 described above.

When the circuit-connecting adhesive film has a layer other than the first adhesive layer and the second adhesive layer (for example, a third adhesive layer), the thickness of the circuit-connecting adhesive film (for circuit-connecting The total thickness of all layers constituting the adhesive film) may be the same as the possible thickness range of the circuit-connecting adhesive film 10A.

<Method for producing adhesive film for circuit connection>
A method for manufacturing an adhesive film for circuit connection of one embodiment comprises a predetermined first adhesive layer and a predetermined second adhesive layer provided on the first adhesive layer. Although it is not particularly limited as long as an adhesive film for circuit connection can be obtained, from the viewpoint of easily obtaining an adhesive film for circuit connection with a high monodispersity ratio, for example, the surface has a plurality of recesses, and each of the plurality of recesses A step of preparing a substrate on which the component (A) is arranged (preparation step), and on the surface of the substrate (the surface on which the recess is formed), the component (B) and the first thermosetting resin component A step of transferring the component (A) to the composition layer (transfer step) by providing a composition layer containing A step of forming a first adhesive layer containing a cured product of and (C) component (first thermosetting resin component) (light irradiation step), and on one side of the first adhesive layer and a step of providing a second adhesive layer containing a second thermosetting resin component (lamination step).

The method for manufacturing the circuit-connecting adhesive film 10A will be described below with reference to FIGS. 3 to 6, taking the circuit-connecting adhesive film 10A as an example.

FIG. 3 is a schematic cross-sectional view of a substrate used for manufacturing the circuit-connecting adhesive film of FIG. FIG. 4 is a diagram showing a state in which conductive particles are arranged in the recesses of the base shown in FIG. FIG. 5 is a schematic cross-sectional view showing one step of the method for producing the circuit-connecting adhesive film of FIG. 1, and is a cross-sectional view schematically showing an example of the transfer step. FIG. 6 is a schematic cross-sectional view showing one step of the method for manufacturing the adhesive film for circuit connection of FIG. 1, and is a cross-sectional view schematically showing an example of the light irradiation step.

(Preparation process)
In the preparation step, first, a substrate 6 having a plurality of recesses 7 on its surface is prepared (see FIG. 3). Base 6 has a plurality of recesses 7 . The plurality of recesses 7 are, for example, regularly arranged in a predetermined pattern (for example, a pattern corresponding to the electrode pattern of the circuit member). When the concave portions 7 are arranged in a predetermined pattern, the conductive particles 4 are transferred to the composition layer in a predetermined pattern. Therefore, the circuit-connecting adhesive film 10A in which the conductive particles 4 are regularly arranged in a predetermined pattern can also be obtained.

For example, as shown in FIG. 3, the recess 7 of the base 6 is tapered such that the opening area increases from the bottom 7a of the recess 7 toward the surface 6a of the base 6 . That is, the width of the bottom portion 7a of the recess 7 (width a in FIG. 3) is narrower than the width of the opening of the recess 7 (width b in FIG. 3). The size (width a, width b, volume, taper angle, depth, etc.) of the recesses 7 can be set according to the intended size of the conductive particles and the position of the conductive particles in the circuit-connecting adhesive film. For example, the width (width b) of the opening of the recess 7 may be larger than the maximum particle size of the conductive particles 4 and may be less than twice the maximum particle size of the conductive particles.

The shape of the opening of the recess 7 may be circular, elliptical, triangular, quadrangular, polygonal, or the like.

The recesses 7 of the substrate 6 can be formed by known methods such as lithography and machining. With these methods, the size and shape of the recess can be freely designed.

Materials constituting the base 6 include, for example, silicon, various ceramics, glass, inorganic materials such as metals such as stainless steel, and organic materials such as various resins. As will be described later, in the method of manufacturing the circuit-connecting adhesive film of the present embodiment, the conductive particles 4 can be arranged in the recesses 7 of the substrate 6 by forming the conductive particles 4 in the recesses 7 of the substrate 6. In this case, the substrate 6 may be made of a heat-resistant material that does not deteriorate at the melting temperature of the fine particles (for example, solder fine particles) used to form the conductive particles 4 .

Next, the conductive particles 4 (component (A) above) are placed (accommodated) in each of the plurality of recesses 7 of the substrate 6 (see FIG. 4).

The arrangement method of the conductive particles 4 is not particularly limited. The arrangement method may be either dry or wet. For example, the conductive particles 4 are placed on the surface 6a of the substrate 6, and a squeegee or a slightly adhesive roller is used to rub the surface 6a of the substrate 6, thereby removing the excess conductive particles 4 and filling the concave portions 7 with the conductive particles. 4 can be placed. If the width b of the opening of the recess 7 is greater than the depth of the recess 7 , the conductive particles may fly out of the opening of the recess 7 . By using a squeegee, the conductive particles protruding from the openings of the recesses 7 can be removed. Methods for removing excess conductive particles include, for example, a method of blowing compressed air, a method of rubbing the surface 6a of the substrate 6 with a nonwoven fabric or a bundle of fibers, and the like. These methods are preferable for handling easily deformable particles (for example, solder particles) as conductive particles because the physical force is weaker than that of squeegees. Moreover, in these methods, the conductive particles protruding from the openings of the recesses 7 can be left in the recesses 7 .

When the conductive particles 4 are solder particles, in the method for producing a circuit-connecting adhesive film according to the present embodiment, the conductive particles 4 (solder particles) are formed in the recesses 7 of the substrate 6 so that the conductive particles 4 are formed in the recesses. 7 may be placed. Specifically, fine particles (solder fine particles) for forming the conductive particles 4 are accommodated in the recesses 7 . Next, the conductive particles 4 can be formed in the recesses 7 by melting and fusing the fine particles accommodated in the recesses 7 . The fine particles accommodated in the recesses 7 are united by melting and spheroidized by surface tension. At this time, the molten metal follows the bottom of the recesses 7 at the contact area. . Therefore, for example, when the bottom of the concave portion 7 is flat, the conductive particle 4 has a flat portion 4a on a part of the surface.

After placing the conductive particles 4 in the recesses 7 , the substrate 6 can be handled with the conductive particles 4 placed (accommodated) in the recesses 7 . For example, when the substrate 6 is transported or stored with the conductive particles 4 arranged (accommodated) in the recesses 7, deformation of the conductive particles 4 (especially soft conductive particles such as solder particles) can be prevented. In addition, when the conductive particles 4 are arranged (accommodated) in the recesses 7, the conductive particles 4 can be easily taken out. Therefore, it tends to be easy to prevent deformation when the conductive particles 4 are collected and subjected to surface treatment. .

(Transfer process)
In the transfer step, the photocurable resin component (component (B) above) and the first thermosetting resin component (component (C) above) are applied onto the surface of the substrate 6 (the surface on which the recesses 7 are formed). By providing the containing composition layer 9, the conductive particles 4 are transferred to the composition layer 9 (see FIG. 5).

Specifically, first, a laminate film 12 is produced by forming a composition layer 9 containing components (B) and (C) on a support 11 . Next, the surface of the substrate 6 on which the recesses 7 are formed (the surface 6a of the substrate 6) and the surface of the laminate film 12 on the composition layer 9 side (the surface 9a of the composition layer 9 on the side opposite to the support 11). are opposed to each other to bring the substrate 6 and the composition layer 9 close to each other (see FIG. 5(a)). Next, by bonding the laminated film 12 and the substrate 6 together, the composition layer 9 is brought into contact with the surface 6a of the substrate 6 (the surface where the recesses 7 are formed), and the conductive particles 4 are transferred to the composition layer 9. do. As a result, the particle transfer layer 13 including the composition layer 9 and the conductive particles 4 at least partially embedded in the composition layer 9 is obtained (see FIG. 5(b)). At this time, when the bottom of the concave portion 7 is flat, the conductive particles 4 have a flat portion 4a corresponding to the shape of the bottom of the concave portion 7, and the flat portion 4a faces the side opposite to the support 11. It is arranged in the composition layer 9 in a state.

The composition layer 9 is prepared by dissolving or dispersing components (B) and (C), and other components added as necessary, in an organic solvent by stirring, mixing, kneading, or the like. , a varnish composition (varnish-like first adhesive composition). Specifically, for example, the varnish composition is applied onto the support 11 (for example, a base material subjected to a release treatment) using a knife coater, roll coater, applicator, comma coater, die coater, or the like. Then, the composition layer 9 can be formed by volatilizing the organic solvent by heating. At this time, the thickness of the finally obtained first adhesive layer can be adjusted by adjusting the coating amount of the varnish composition.

The organic solvent used in the preparation of the varnish composition is not particularly limited as long as it has the property of uniformly dissolving or dispersing each component. Examples of such organic solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate and the like. These organic solvents can be used individually by 1 type or in combination of 2 or more types. Stirring and mixing or kneading during preparation of the varnish composition can be performed using, for example, a stirrer, a kneader, a three-roll mill, a ball mill, a bead mill, a homodisper, or the like.

The support 11 is not particularly limited as long as it has heat resistance that can withstand the heating conditions when volatilizing the organic solvent. The support 11 may be a plastic film or a metal foil. Examples of the support 11 include oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene/ Substrates (for example, films) made of vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, synthetic rubbers, liquid crystal polymers, and the like are included.

The heating conditions for volatilizing the organic solvent from the varnish composition applied to the support 11 can be appropriately set according to the organic solvent used. The heating conditions may be, for example, 40 to 120° C. for 0.1 to 10 minutes.

Examples of methods for bonding the laminated film 12 and the substrate 6 include heat press, roll lamination, and vacuum lamination. Lamination can be performed, for example, under temperature conditions of 0 to 80°C.

In the transfer step, the composition layer 9 may be formed by directly applying the varnish composition to the substrate 6, but by using the laminated film 12, the support 11, the composition layer 9 and the conductive particles 4 are integrated. It becomes easy to obtain the particle transfer layer 13 having a high density, and there is a tendency that the light irradiation step to be described later can be easily performed.

(Light irradiation step)
In the light irradiation step, the composition layer 9 (particle transfer layer 13) is irradiated with light (actinic rays) to cure the component (B) in the composition layer 9 and form the first adhesive layer 1. (see Figure 6).

For the light irradiation, irradiation light containing wavelengths within the range of 150 to 750 nm (eg, ultraviolet light) may be used. Light irradiation can be performed using, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a metal halide lamp, an LED light source, or the like. The integrated amount of light to be irradiated can be appropriately set, and may be, for example, 500 to 3000 mJ/cm ² .

In FIG. 6A, as indicated by an arrow, the light is irradiated from the side opposite to the support 11 (the side of the composition layer 9 to which the conductive particles 4 are transferred), but the support 11 receives the light. In the case of transmission, the light may be irradiated from the support 11 side. In FIG. 6A, the light irradiation is performed after the substrate 6 and the particle transfer layer 13 are separated, but the light irradiation may be performed before the substrate 6 is separated. In this case, light irradiation may be performed after the support 11 is peeled off.

(Lamination process)
In the lamination step, the second adhesive layer 2 is provided on the surface of the first adhesive layer 1 opposite to the support 11 (the side of the composition layer 9 to which the conductive particles 4 are transferred). Thereby, the circuit-connecting adhesive film 10A shown in FIG. 1 can be obtained.

The second adhesive layer 2 contains, instead of the first adhesive composition, a second thermosetting resin component (component (C) above) and other components added as necessary, organic A method of providing a composition layer 9 on a substrate 6, except for using a varnish composition (second adhesive composition) prepared by dissolving or dispersing by stirring, mixing, kneading, or the like in a solvent. can be provided on the first adhesive layer 1 in the same manner as in . That is, the second adhesive layer is formed on the first adhesive layer 1 by laminating the laminated film obtained by forming the second adhesive layer 2 on the support and the first adhesive layer 1. 2 may be provided, and the second adhesive layer 2 may be provided on the first adhesive layer 1 by directly applying the second adhesive composition to the first adhesive layer 1 .

In the lamination step, by providing the second adhesive layer 2 on the surface opposite to the support 11, the adhesion of the circuit connection adhesive film to the circuit member is improved and the peeling during connection is suppressed. I can expect it. In the lamination step, after peeling off the support 11, the second adhesive layer 2 may be provided on the surface on which the support 11 was provided. In this case, the lamination step may be performed before the light irradiation step, or may be performed before the transfer step.

As described above, the method for manufacturing the circuit-connecting adhesive film 10A is taken as an example to describe the method for manufacturing the circuit-connecting adhesive film according to one embodiment, but the present disclosure is not limited to the above-described embodiment.

For example, the method for producing an adhesive film for circuit connection includes providing a third adhesive layer on the surface of the first adhesive layer opposite to the second adhesive layer (second laminating step ) may be further provided. According to such a manufacturing method, it is possible to obtain a circuit-connecting adhesive film (for example, the circuit-connecting adhesive film 10B shown in FIG. 2) further comprising a third adhesive layer.

The third adhesive layer contains, instead of the second adhesive composition, a third thermosetting resin component (component (C) above) and other components added as necessary in an organic solvent. The above laminate for providing the second adhesive layer, except for using a varnish composition (third adhesive composition) prepared by dissolving or dispersing by stirring, mixing, kneading, etc. in A third adhesive layer can be provided on the first adhesive layer in the same manner as in the step (first lamination step). The second lamination step may be performed before the first lamination step.

<Circuit connection structure and its manufacturing method>
Hereinafter, a circuit connection structure and a method for producing the same will be described, taking as an example an aspect in which the circuit connection adhesive film 10A is used as a circuit connection material.

FIG. 7 is a schematic cross-sectional view showing one embodiment of the circuit connection structure. As shown in FIG. 7 , the circuit connection structure 100 includes a first circuit board 21 and a first circuit member 23 having a first electrode 22 formed on a main surface 21 a of the first circuit board 21 . , a second circuit member 26 having a second circuit board 24 and a second electrode 25 formed on the main surface 24a of the second circuit board 24, and a cured body of the circuit-connecting adhesive film 10A. , is arranged between the first circuit member 23 and the second circuit member 26, and the first electrode 22 and the second electrode 25 are connected to each other via the conductive particles 4 (or the melted and solidified conductive particles 4). A circuit connection portion 27 for electrically connecting and bonding the first circuit member 23 and the second circuit member 26 is provided.

The first circuit member 23 and the second circuit member 26 may be the same or different from each other. The first circuit member 23 and the second circuit member 26 may be a glass substrate or plastic substrate on which electrodes are formed, a printed wiring board, a ceramic wiring board, a flexible wiring board, an IC chip, or the like. The first circuit board 21 and the second circuit board 24 may be made of an inorganic material such as semiconductor, glass, or ceramic, an organic material such as polyimide or polycarbonate, a composite material such as glass/epoxy, or the like. Among these, since the circuit connection adhesive film 10A can be suitably used for COP mounting, the first circuit member 23 is a plastic substrate made of an organic substance such as polyimide, polycarbonate, polyethylene terephthalate, cycloolefin polymer, or the like. and the second circuit board 24 may be, for example, an IC chip.

The first electrode 22 and the second electrode 25 are metals such as gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, titanium, indium tin oxide (ITO), Electrodes may include oxides such as indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), and the like. The first electrode 22 and the second electrode 25 may be electrodes formed by stacking two or more of these metals, oxides, and the like. The electrode formed by laminating two or more kinds may have two or more layers, or may have three or more layers. When the first circuit member 23 is a plastic substrate, the first electrode 22 may be an electrode having a titanium layer on its outermost surface. The first electrode 22 and the second electrode 25 may be circuit electrodes or bump electrodes. At least one of the first electrode 22 and the second electrode 25 may be a bump electrode. The circuit connection structure shown in FIG. 7 is of a mode in which the first electrodes 22 are circuit electrodes and the second electrodes 25 are bump electrodes.

The circuit connection portion 27 includes a cured body of the circuit connection adhesive film 10A. The circuit connection portion 27 may be made of a cured body of the circuit connection adhesive film 10A. The circuit connection portion 27 is positioned, for example, on the first circuit member 23 side in the direction in which the first circuit member 23 and the second circuit member 26 face each other (hereinafter, “opposing direction”), and A first cured body region 28 made of a cured body derived from the first adhesive layer of and located on the second circuit member 26 side in the opposite direction and composed of a cured body derived from the second adhesive layer The second cured body region 29 and the conductive particles 4 interposed between at least the first electrode 22 and the second electrode 25 to electrically connect the first electrode 22 and the second electrode 25 to each other have. As shown in FIG. 7, the circuit connection portion 27 may not have two distinct cured regions, a first cured region 28 and a second cured region 29. A cured body derived from the adhesive layer and a cured body derived from the second adhesive layer may be mixed to form one cured body region.

FIG. 8 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a circuit connection structure. 8A and 8B are schematic cross-sectional views showing each step. As shown in FIG. 8, in the method of manufacturing the circuit connection structure 100, between a first circuit member 23 having a first electrode 22 and a second circuit member 26 having a second electrode 25, A step of electrically connecting the first electrode 22 and the second electrode 25 to each other by thermocompression bonding the first circuit member 23 and the second circuit member 26 with the circuit connection adhesive film 10A interposed. Prepare.

Specifically, first, the first circuit board 21 and the first circuit member 23 including the first electrodes 22 formed on the main surface 21a of the first circuit board 21, and the second circuit board 24 and a second circuit member 26 having a second electrode 25 formed on the main surface 24a of the second circuit board 24 are prepared.

Next, the first circuit member 23 and the second circuit member 26 are arranged so that the first electrode 22 and the second electrode 25 face each other, and the first circuit member 23 and the second circuit member 26, the adhesive film 10A for circuit connection is arranged. For example, as shown in FIG. 8A, the circuit connecting adhesive film 10A is placed on the first circuit member 23 so that the first adhesive layer 1 faces the main surface 21a of the first circuit board 21. Laminate on top. Next, the circuit-connecting adhesive film 10A was laminated so that the first electrodes 22 on the first circuit board 21 and the second electrodes 25 on the second circuit board 24 faced each other. A second circuit member 26 is placed on the first circuit member 23 .

Then, as shown in FIG. 8B, while heating the first circuit member 23, the circuit-connecting adhesive film 10A, and the second circuit member 26, the first circuit member 23 and the second circuit are heated. By pressing the member 26 in the thickness direction, the first circuit member 23 and the second circuit member 26 are thermocompression bonded to each other. At this time, as indicated by arrows in FIG. 8(b), since the second adhesive layer 2 has a flowable uncured thermosetting resin component, the second electrodes 25 are separated from each other. It flows so as to fill the voids of the adhesive and hardens by heating during thermocompression bonding. As a result, the first electrode 22 and the second electrode 25 are electrically connected to each other through the conductive particles 4, and the first circuit member 23 and the second circuit member 26 are adhered to each other. 2 can be obtained.

In the method for manufacturing the circuit connection structure 100 of the present embodiment, since it can be said that the first adhesive layer 1 is partially cured by light irradiation, the conductive particles 4 are fixed in the first adhesive layer 1. In addition, since the first adhesive layer 1 hardly flows during thermocompression bonding and the conductive particles are efficiently captured between the facing electrodes, the first electrode 22 and the second electrode facing each other 25 is reduced. Further, the thickness of the first adhesive layer is 5.0 μm or less, and the ratio of the thickness of the first adhesive layer to the average particle size of the conductive particles is 0.50 or more. It is possible to suppress the increase in the connection resistance between the opposing circuits by reducing the amount of resin between them.

The heating temperature for thermocompression bonding can be appropriately set, and may be, for example, 50 to 190°C. The pressure is not particularly limited as long as it does not damage the adherend. In the case of COP mounting, for example, the area conversion pressure at the bump electrode may be 0.1 to 50 MPa, and 0.1 to 40 MPa. may be Further, in the case of COG mounting, for example, the area-converted pressure at the bump electrode may be 10 to 100 MPa. These heating and pressurizing times may range from 0.5 to 120 seconds.

Hereinafter, the present disclosure will be described more specifically with reference to Examples. However, the present disclosure is not limited to these examples.

In the examples and comparative examples, the following materials were used as the (B1) component, (B2) component, (b2) component, (C1) component, (C2) component, (D) component, (E) component, and ( F) Used as a component.

(B) component: photocurable resin component (B1) component: radical polymerizable compound radical polymerizable compound B1-1: NK ester A-BPEF (ethoxylated fluorene type di (meth) acrylate (bifunctional), Shin-Nakamura Chemical manufactured by Kogyo Co., Ltd.)
Radically polymerizable compound B1-2: Lipoxy VR-90 (bisphenol A type epoxy (meth) acrylate (bifunctional) (vinyl ester resin), manufactured by Showa Denko K.K.)
(B2) Component: Photoradical polymerization initiator Photoradical polymerization initiator B2-1: Omnirad 184 (a compound having an α-hydroxyalkylphenone structure, manufactured by IGM Resins)
Photoradical polymerization initiator B2-2: Omnirad 907 (a compound having an α-aminoalkylphenone structure, manufactured by IGM Resins)
Component (b2): Photoradical polymerization initiator Photoradical polymerization initiator b2-1: Omnirad TPO (a compound having an acylphosphine oxide structure, manufactured by IGM Resins)
Photoradical polymerization initiator b2-2: Omnirad MBF (intramolecular hydrogen abstraction type, methyl benzoylformate, manufactured by IGM Resins)

(C) component: thermosetting resin component (C1) component: cationically polymerizable compound cationically polymerizable compound C1-1: ETERNACOLL OXBP (oxetane compound, manufactured by Ube Industries, Ltd.)
Cationic polymerizable compound C1-2: OXSQ (oxetane compound, manufactured by Toagosei Co., Ltd.)
Cationic polymerizable compound C1-3: EHPE3150 (alicyclic epoxy compound, manufactured by Daicel Co., Ltd.)
Cationic polymerizable compound C1-4: Celoxide 2021P (alicyclic epoxy compound, manufactured by Daicel Co., Ltd.)
Cationic polymerizable compound C1-5: jER1007 (epoxy compound, manufactured by Mitsubishi Chemical Corporation)
(C2) Component: Thermal cationic polymerization initiator Thermal cationic polymerization initiator C2-1: CXC-1821 (manufactured by King Industries)

(D) Component: Thermoplastic resin Thermoplastic resin D-1: Phenotote FX-293 (phenoxy resin, manufactured by Nippon Steel Chemical & Materials Co., Ltd.)
Thermoplastic resin D-2: Phenotote YP-50S (phenoxy resin, manufactured by Nippon Steel Chemical & Materials Co., Ltd.)
Thermoplastic resin D-3: Phenotote ZX-1356-2 (phenoxy resin, manufactured by Nippon Steel Chemical & Materials Co., Ltd.)

(E) Component: Coupling agent Coupling agent E-1: SH-6040 (3-glycidoxypropyltrimethoxysilane, manufactured by Dow Corning Toray Co., Ltd.)

(F) Component: Filler Filler F-1: Aerosil R805 (silica fine particles, manufactured by Evonik Industries AG)
Filler F-2: ADMAFINE SE2050 (silica fine particles, manufactured by Admatechs Co., Ltd.)

(Example 1)
[Preparation of adhesive film for circuit connection]
<Step (a): Preparatory step>
Step (a1): Preparation of substrate A substrate (PET film, thickness: 55 µm) having a plurality of recesses on its surface was prepared. The concave portion has a truncated cone shape with an opening area that expands toward the surface of the substrate (the center of the bottom and the center of the opening are the same when viewed from the top of the opening), and has an opening diameter of 4.3 μmφ and a bottom diameter of 4. 0 μmφ, depth: 4.0 μm. In addition, the plurality of recesses were regularly formed in a three-sided arrangement at intervals of 8.0 μm (center-to-center distance of each bottom) so that the density of the conductive particles was 18000 per 1 mm ² (18000/mm ² ). .

・Step (a2): Arrangement of conductive particles As the component (A), conductive particles A-1 (average particle size: 3.2 μm) are obtained by Ni-plating the surface of the plastic core and displacing the outermost surface with Pd. ) was prepared and placed on the surface of the base on which the recesses were formed. Then, the surface of the substrate on which the recesses are formed was rubbed with a slightly adhesive roller to remove excess conductive particles, which were placed only in the recesses. The average particle diameter of the conductive particles A-1 is obtained by cutting the first adhesive layer prepared through the steps (b) and (c) described later into 10 cm × 10 cm, and on the surface on which the conductive particles are arranged. It is a value measured by SEM observation of 300 conductive particles after Pt sputtering.

<Step (b): Transfer step>
- Step (b1): Preparation of composition layer The (B1) component, (B2) component, (C1) component, (C2) component, (D) component, and (E) component shown in Table 1 are was mixed with an organic solvent (2-butanone) at a compounding amount (unit: parts by mass, solid content) shown in , to obtain a varnish-like first adhesive composition. Next, the first adhesive composition was applied to a PET film having a thickness of 38 μm that had been subjected to silicone release treatment, and dried with hot air at 60° C. for 3 minutes to form a composition layer having a thickness of 2.0 μm on the PET film. was made.

Step (b2): transfer of conductive particles The composition layer formed on the PET film prepared in step (b1) and the substrate having conductive particles arranged in recesses prepared in step (a) They were placed face to face, and the conductive particles were transferred to the composition layer so that the content of component (A) was approximately 37% by mass based on the total mass of the composition layer.

<Step (c): Light irradiation step>
A UV curing furnace (UVC-2534/1MNLC3-XJ01, manufactured by Ushio Inc.) was used to apply an integrated amount of light of 2000 mJ to the composition layer to which the conductive particles were transferred using a metal halide lamp from the side on which the conductive particles were transferred. /cm ² (wavelength: 365 nm) to activate component (B2) and polymerize component (B1). As a result, the photocurable components (components (B1) and (B2)) in the composition layer were cured to form a first adhesive layer.

<Step (d): Lamination step>
- Step (d1): Preparation of the second adhesive layer The components (C1), (C2), (D), (E), and (F) shown in Table 2 are shown in Table 2. It was mixed with an organic solvent (2-butanone) in a blending amount (unit: parts by mass, solid content) to obtain a varnish-like second adhesive composition. Then, a second adhesive layer was formed on the PET film by applying the second adhesive composition to a PET film having a thickness of 50 μm that had been subjected to silicone release treatment and drying with hot air at 60° C. for 3 minutes. .

- Step (d2): Lamination of the second adhesive layer The first adhesive layer prepared in the step (c) and the second adhesive layer prepared in the step (d1) I glued them together while putting them on. As a result, an adhesive film for circuit connection having a two-layer structure was obtained.

<Step (e): Second Lamination Step>
・Step (e1): Preparation of the third adhesive layer The components (C1), (C2), (D), (E) and (F) shown in Table 3 are combined as shown in Table 3. A varnish-like third adhesive composition was obtained by mixing with an organic solvent (2-butanone) in an amount (unit: parts by mass, solid content). Then, a third adhesive layer was prepared on the PET film by applying the third adhesive composition to a 50 μm thick PET film that had been subjected to a silicone release treatment and drying with hot air at 60° C. for 3 minutes. .

Step (e2): Lamination of third adhesive layer The third adhesive layer exposed by peeling off the PET film on the first adhesive layer side of the two-layer circuit connection adhesive film produced in step (d2) The adhesive layer No. 1 and the third adhesive layer prepared in the step (e1) were laminated while applying a temperature of 50°C. Thus, an adhesive film for circuit connection having a three-layer structure of Example 1 was obtained.

[Measurement of Thickness of Each Adhesive Layer in Adhesive Film for Circuit Connection]
With respect to the circuit-connecting adhesive film of Example 1, the thicknesses of the first adhesive layer, the second adhesive layer, and the third adhesive layer were measured. In the measurement, the adhesive film for circuit connection was sandwiched between two sheets of glass (thickness: about 1 mm), and 100 g of bisphenol A type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and a curing agent (trade name: Epomount curing agent, manufactured by Refinetech Co., Ltd.) 10 g of the resin composition is cast, the cross section is polished using a polishing machine, and a scanning electron microscope (SEM, trade name: SE-8020, Hitachi, Ltd.) is used. Hitech Science) was used to measure the thickness of the first adhesive layer, the second adhesive layer, and the third adhesive layer. The first adhesive layer, second adhesive layer, and third adhesive layer were 2.0 μm, 12.0 μm, and 1.0 μm, respectively.

[Monodispersion of Conductive Particles in Circuit Connection Adhesive Film]
The circuit-connecting adhesive film of Example 1 was observed from the first adhesive layer side at a magnification of 200 using a metallurgical microscope, and the number of conductive particles in the circuit-connecting adhesive film was actually measured. obtained according to the formula. The monodispersity of the conductive particles was 99%.
Monodisperse rate (%) = (number of monodispersed conductive particles in 2500 µm ² / number of conductive particles in 2500 µm ² ) x 100

(Example 2 and Comparative Examples 1 and 2)
Example 2 was prepared in the same manner as in Example 1, except that in step (b1), the type and/or amount of the material to be blended and in step (c), the integrated amount of light was changed as shown in Table 4. And three-layer circuit connection adhesive films of Comparative Examples 1 and 2 were produced. Regarding the adhesive films for circuit connection of Example 2 and Comparative Examples 1 and 2, the thickness of each adhesive layer and the monodispersity of the conductive particles were obtained in the same manner as in Example 1. Table 5 shows the results.

[Evaluation of capture rate of conductive particles and evaluation of connection resistance]
(Preparation of circuit members)
As a first circuit member, a wiring pattern (pattern Width: 19 µm, space between electrodes: 5 µm) was prepared. As a second circuit member, an IC chip in which bump electrodes are arranged in two rows in a zigzag pattern (outer shape: 0.9 mm × 20.3 mm, thickness: 0.3 mm, size of bump electrodes: 70 µm × 12 µm, bump electrodes space: 12 μm, bump electrode thickness: 9 μm).

(Preparation of circuit connection structure)
Using the circuit-connecting adhesive films of Examples 1 and 2 and Comparative Examples 1 and 2, circuit-connecting structures were produced. The circuit-connecting adhesive film was placed on the first circuit member such that the third adhesive layer of the circuit-connecting adhesive film and the first circuit member were in contact with each other. Using a thermocompression bonding device (BS-17U, manufactured by Ohashi Seisakusho Co., Ltd.) consisting of a stage consisting of a ceramic heater and a tool (8 mm × 50 mm), under the conditions of 70 ° C. and 0.98 MPa (10 kgf / cm ² ). The circuit-connecting adhesive film was adhered to the first circuit member by applying heat and pressure for 2 seconds, and the release film on the opposite side of the circuit-connecting adhesive film to the first circuit member was peeled off. Next, after aligning the bump electrodes of the first circuit member and the circuit electrodes of the second circuit member, the measured maximum temperature of the adhesive film for circuit connection was 170° C., and the area conversion pressure at the bump electrodes was 30 MPa. The second adhesive layer of the circuit connection adhesive film is attached to the second circuit member by heating and pressing for 5 seconds under the conditions of Examples 1 and 2 and Comparative Examples 1 and 2. made the body.

(Evaluation of capture rate of conductive particles)
In the circuit connection structures of Examples 1 and 2 and Comparative Examples 1 and 2, the trapping rate of conductive particles between the bump electrodes and the circuit electrodes was evaluated. Here, the capture rate of the conductive particles means the ratio of the conductive particle density on the bump electrode to the conductive particle density in the adhesive film, and was calculated from the following formula. In addition, the average number of conductive particles on the bump electrode was obtained by observing the mounted circuit member from the polyimide substrate using a differential interference microscope and measuring the number of conductive particles captured per bump through the metal electrode. asked. "S" judgment when the capture rate of the conductive particles is 50% or more, "A" judgment when the capture rate of the conductive particles is 40% or more and less than 50%, and the capture rate of the conductive particles is less than 40%. The case where it was was evaluated as "B" judgment. Table 6 shows the results.
Capture rate of conductive particles (%) = (average number of conductive particles on bump electrode/(bump electrode area x density of conductive particles in adhesive film)) x 100

(Evaluation of connection resistance)
Using the circuit connection structures of Examples 1 and 2 and Comparative Examples 1 and 2, connection resistance was evaluated. The connection resistance was evaluated by the four-terminal measurement method immediately after the circuit connection structure was produced and after the high-temperature and high-humidity test, and the average value of the connection resistance values measured at 14 points was used for evaluation. The high-temperature and high-humidity test was performed by treating the circuit connection structure for 500 hours in a high-temperature and high-humidity test chamber at a temperature of 85° C. and a humidity of 85% RH. A multimeter (MLR21, manufactured by Kusumoto Kasei Co., Ltd.) was used to measure the connection resistance. Immediately after the production of the circuit connection structure, the case where the connection resistance value was less than 0.5Ω was judged as “S”, and the case where the connection resistance value was 0.5Ω or more and less than 1.0Ω was judged as “A”. A case where the resistance value was 1.0Ω or more was evaluated as "B" judgment. After the high-temperature and high-humidity test, if the connection resistance value is less than 0.5Ω, it is judged as "S", and if the connection resistance value is 0.5Ω or more and less than 1.5Ω, it is judged as "A". was 1.5Ω or more was evaluated as "B". Table 6 shows the results.

As shown in Table 6, the circuit-connecting adhesive films of Examples 1 and 2 had a lower conductive particle trapping rate and connection resistance than the circuit-connecting adhesive films of Comparative Examples 1 and 2 in mounting at a low pressure. Excellent on both counts. From these results, the circuit connection adhesive film of the present disclosure improves the capture rate of conductive particles between the opposing electrodes of the circuit connection structure even when mounted at a low pressure, and the circuit connection structure It was confirmed that it is possible to reduce the connection resistance of

DESCRIPTION OF SYMBOLS 1... First adhesive layer, 2... Second adhesive layer, 3... Adhesive component, 4... Conductive particles, 5... Third adhesive layer, 6... Substrate, 7... Recess, 9... Composition Layers 10A, 10B... Adhesive film for circuit connection 21... First circuit board 22... First electrode (circuit electrode) 23... First circuit member 24... Second circuit board 25... Second electrode (bump electrode) 26 Second circuit member 27 Circuit connection part 100 Circuit connection structure.

Claims (10)

A first adhesive layer containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component;
a second adhesive layer containing a second thermosetting resin component provided on the first adhesive layer;
with
The photocurable resin component contains a radical polymerizable compound and a photoradical polymerization initiator,
The photoradical polymerization initiator contains a compound having an alkylphenone structure,
Adhesive film for circuit connection. The thickness of the first adhesive layer is 5.0 μm or less,
The ratio of the thickness of the first adhesive layer to the average particle size of the conductive particles is 0.50 or more,
The adhesive film for circuit connection according to claim 1. The monodispersity of the conductive particles in the circuit connection adhesive film is 90% or more,
The adhesive film for circuit connection according to claim 1 or 2. The first thermosetting resin component and the second thermosetting resin component contain a cationic polymerizable compound and a thermal cationic polymerization initiator,
The adhesive film for circuit connection according to any one of claims 1 to 3. The cationically polymerizable compound is at least one selected from the group consisting of oxetane compounds and alicyclic epoxy compounds,
The adhesive film for circuit connection according to claim 4. The thermal cationic polymerization initiator is a salt compound having an anion containing boron as a constituent element,
The adhesive film for circuit connection according to claim 4 or 5. Further comprising a third adhesive layer containing a third thermosetting resin component provided on the opposite side of the first adhesive layer to the second adhesive layer,
The adhesive film for circuit connection according to any one of claims 1 to 6. The third thermosetting resin component contains a cationic polymerizable compound and a thermal cationic polymerization initiator,
The adhesive film for circuit connection according to claim 7. Between the first circuit member having the first electrode and the second circuit member having the second electrode, the adhesive film for circuit connection according to any one of claims 1 to 8 is interposed. and thermocompression bonding the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other;
A method for manufacturing a circuit connection structure. a first circuit member having a first electrode;
a second circuit member having a second electrode;
a circuit connection portion disposed between the first circuit member and the second circuit member and electrically connecting the first electrode and the second electrode to each other;
with
wherein the circuit connection portion comprises the cured body of the circuit connection adhesive film according to any one of claims 1 to 8,
Circuit connection structure.

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