Adhesive Film for Circuit Connection, Inorganic Filler-Containing Composition, Circuit Connection Structure, and Method for Manufacturing the Same

Abstract

The adhesive film for circuit connection of the present invention is an adhesive film containing conductive particles. In the thickness direction of the film, the adhesive film includes a region A containing an inorganic filler. The region A is formed from a thermosetting composition containing an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in the volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative.

Description

Technical Field

[0001] The present invention relates to an adhesive film for circuit connection, an inorganic filler-containing composition, a circuit connection structure, and a method for manufacturing the same. Background Art

[0002] In recent years, in the display industry, in the modules of display units, there has been a paradigm shift from liquid crystal displays to organic light-emitting diodes (LEDs), and accordingly, the constituent materials of the panels have changed.

[0003] In conventional liquid crystal displays, a glass substrate is used as the substrate, and for the circuit materials formed on the glass substrate, metals such as aluminum are used for the circuits in the base layer, and indium tin oxide (ITO) etc. are used for the electrodes on the surface layer. On the other hand, in organic LEDs, although there is also a glass substrate, in order to improve design diversity (such as curved displays, foldable displays, etc.), a flexible plastic substrate such as a polyimide substrate is used as the substrate, and Ti is gradually becoming the mainstream as the circuit material formed on the plastic substrate. And, on the lower surface of the polyimide substrate, soft members such as a pressure-sensitive adhesive layer and a polyethylene terephthalate (PET) substrate are usually arranged in order to impart flexibility (for example, refer to Patent Document 1).

[0004] In liquid crystal displays, from the viewpoints of fine pitch, lightweight and thinness, etc., so-called chip on glass (COG) mounting in which various electronic components such as driving ICs are directly mounted on the glass substrate of the display panel is adopted. And, as a COG mounting method, for example, a method of obtaining a circuit connection structure by thermocompression bonding a liquid crystal driving IC to a glass substrate via an anisotropic conductive adhesive film for circuit connection in which conductive particles are dispersed in an adhesive is used.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016-054288 Summary of the Invention

[0008] Technical Problem to be Solved by the Invention

[0009] In organic light-emitting diodes (OLEDs), chip-on-plastic (COP) mounting, where driving ICs and the like are directly mounted on a plastic substrate, is also being adopted. However, if excessive pressure is applied to the plastic substrate, problems such as deformation, cracking, and disconnection of the Ti circuit provided on the plastic substrate may occur as adverse conditions accompanying the deformation of the plastic substrate. Therefore, in COG mounting using an adhesive film for circuit connection, the pressure converted based on the area of the bump electrodes of the IC chip is usually 50 to 100 MPa. However, in COP mounting in organic LEDs, in order to prevent disconnection of the circuit, for example, mounting based on a low pressure of 40 MPa or less is preferred. Also, in COG mounting, there is an advantage of improving the selectivity of connection components and peripheral components when mounting at a low pressure. For example, it is possible to expect thinning of the connection structure by being able to mount on a thinned glass substrate.

[0010] However, in an assembly produced under such low-pressure conditions, the connection resistance between the opposing electrodes tends to be high, and it is difficult to obtain sufficient conduction characteristics. Therefore, the inventors of the present invention have explored ways to increase the fluidity of the adhesive present between the conductive particles and the electrodes during thermocompression bonding of the adhesive film. It is considered effective to blend inorganic fillers such as silica fillers with a relatively large primary particle size when designing the adhesive to be highly fluid. However, according to the investigations by the inventors of the present invention, if commonly available silica fillers are blended, problems such as false defect judgments by an automatic visual inspection device may occur. In order to improve production efficiency, it is desirable to reduce the occurrence of false defect judgments. Therefore, as a result of investigating the main cause of this problem, it has been clearly found that indentations significantly stronger visually than those caused by the conductive particles (hereinafter, also referred to as large indentations) are generated in the wiring portion of the mounting area of the circuit connection structure.

[0011] Accordingly, an object of the present invention is to provide an adhesive film for circuit connection and an inorganic filler-containing composition suitable for manufacturing such circuit connection components, which can sufficiently ensure conduction between opposing electrodes of a circuit connection structure even when circuit components are connected at a low pressure, and can sufficiently suppress the generation of large indentations that are the main cause of false defect judgments by an automatic visual inspection device. Another object of the present invention is to provide a method for manufacturing a circuit connection structure and a circuit connection structure using the above-described adhesive film for circuit connection.

[0012] Means for Solving the Technical Problem

[0013] In order to solve the above problems, one aspect of the present invention provides an adhesive film for circuit connection, which contains conductive particles. The adhesive film includes a region A containing an inorganic filler in the thickness direction of the film. The region A is formed of a thermosetting composition containing an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in the volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative.

[0014] According to the adhesive film for circuit connection of the above aspect, by containing an inorganic filler having the above specific particle size distribution in the region A, it is possible to ensure high fluidity while restricting the inclusion of inorganic fillers that generate large indentations in the film. Even when circuit components are connected to each other at a low pressure, conduction between the opposing electrodes of the circuit connection structure can be sufficiently ensured, and the generation of large indentations, which is the main cause of defective determination by an automatic appearance inspection device, can be sufficiently suppressed.

[0015] The adhesive film for circuit connection of the above aspect may include a region S that does not contain conductive particles in the thickness direction of the film, and the region A is provided in at least a part of the region S. At this time, it is easy to prevent bridging based on conductive particles between the circuit electrodes of the adherend (for example, circuit components) that are in contact on the region A side.

[0016] In the adhesive film for circuit connection of the above aspect, the inorganic filler may be a silica filler.

[0017] Another aspect of the present invention provides an adhesive film for circuit connection, which includes: a first adhesive layer containing a conductive particle, a cured product of a photocurable resin component, and a first thermosetting resin component; and a second adhesive layer provided on the first adhesive layer and containing a second thermosetting resin component. The second adhesive layer is formed of a composition containing an inorganic filler, and the composition containing an inorganic filler contains a second thermosetting resin component and an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in the volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative.

[0018] According to the adhesive film for circuit connection of the above another aspect, even when circuit components are connected to each other at a low pressure, conduction between the opposing electrodes of the circuit connection structure can be sufficiently ensured, and the generation of large indentations, which is the main cause of defective determination by an automatic appearance inspection device, can be sufficiently suppressed. Moreover, according to this adhesive film for circuit connection, the flow of conductive particles during circuit connection can be suppressed by the photocured product, so that conductive particles can be efficiently captured on the electrodes, and high connection reliability can be easily obtained.

[0019] In the adhesive film for circuit connection according to the above-described another aspect, the inorganic filler may be a silica filler.

[0020] The adhesive film for circuit connection according to the above-described another aspect may further include a third adhesive layer, which is laminated on the side of the first adhesive layer opposite to the second adhesive layer and contains a third thermosetting resin component.

[0021] By providing the above-described third adhesive layer, the adhesive film for circuit connection according to the above-described another aspect can easily ensure transferability and characteristics in various reliability tests, and can easily increase the margin of the product.

[0022] Another aspect of the present invention provides an inorganic filler-containing composition for forming an inorganic filler-containing region in a circuit connection component containing conductive particles and an inorganic filler. The composition contains an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in the volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative.

[0023] According to the inorganic filler-containing composition according to the above-described another aspect, it is possible to form region A in the adhesive film for circuit connection according to the above-described one aspect, and an inorganic filler-containing region such as the second adhesive layer in the adhesive film for circuit connection according to the above-described another aspect. Further, with respect to the inorganic filler-containing composition according to the above-described another aspect, even when a thin layer is formed by coating, coating defects are less likely to occur, and the coating yield can be increased. Furthermore, the inorganic filler-containing layer formed from the inorganic filler-containing composition according to the above-described another aspect can sufficiently reduce appearance defects such as scratches.

[0024] In the inorganic filler-containing composition according to the above-described another aspect, the inorganic filler may be a silica filler.

[0025] The inorganic filler-containing composition according to the above-described another aspect can further contain a thermoplastic resin.

[0026] The inorganic filler-containing composition according to the above-described another aspect can be used to form an adhesive layer having a thickness of 10 μm or less.

[0027] Another aspect of the present invention provides a method for manufacturing a circuit connection structure, which includes the following steps: interposing the above-described adhesive film for circuit connection between a first circuit component having a first electrode and a second circuit component having a second electrode, and thermocompression bonding the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other.

[0028] In the method for manufacturing a circuit connection structure according to the above-described another aspect, one of the first circuit component and the second circuit component may be an IC chip, and the other may be a plastic substrate having an electrode containing Ti.

[0029] Another aspect of the present invention provides a circuit connection structure including: a first circuit component having a first electrode; a second circuit component having a second electrode; and a circuit connection portion disposed between the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other, the circuit connection portion including a cured product of the above-mentioned adhesive film for circuit connection.

[0030] In the circuit connection structure of the above-mentioned another aspect, one of the first circuit component and the second circuit component may be an IC chip, and the other may be a plastic substrate having an electrode containing Ti.

[0031] Advantages of the Invention

[0032] According to the present invention, it is possible to provide an adhesive film for circuit connection and an inorganic filler-containing composition suitable for the production of such circuit connection components, in which even when circuit components are connected to each other with a low pressure, conduction between the opposing electrodes of the circuit connection structure can be sufficiently ensured, and generation of large indentations, which are the main cause of defective determination by an automatic visual inspection device, can be sufficiently suppressed. And according to the present invention, it is possible to provide a method for manufacturing a circuit connection structure and a circuit connection structure using the above-mentioned adhesive film for circuit connection. Description of the Drawings

[0033] Figure 1 It is a schematic cross-sectional view showing an embodiment of the adhesive film for circuit connection.

[0034] Figure 2 It is a schematic cross-sectional view showing a manufacturing method of the adhesive film for circuit connection.

[0035] Figure 3 It is a schematic cross-sectional view showing an embodiment of the circuit connection structure.

[0036] Figure 4 It is a schematic cross-sectional view showing an embodiment of the manufacturing process of the circuit connection structure. Detailed Description

[0037] In this specification, the numerical range indicated by "~" represents a range that includes the numerical values before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of a certain stepwise numerical range can be replaced with the upper limit value or the lower limit value of another stepwise numerical range. Also, within the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range can be replaced with the values shown in the examples. Also, the separately described upper limit value and lower limit value can be arbitrarily combined. Also, in this specification, "(meth)acrylate" means at least one of acrylate and the corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl". Also, "(poly)" means both cases with the linker word "poly" and cases without the linker word "poly". Also, "A or B" can include either A or B, or both. Also, regarding the materials exemplified below, unless otherwise specified, one kind can be used alone, or two or more kinds can be used in combination. Regarding the content of each component in the composition, when there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the multiple substances present in the composition.

[0038] Hereinafter, with reference to the drawings as needed, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

[0039] <Adhesive film for circuit connection>

[0040] The adhesive film for circuit connection of this embodiment contains conductive particles and includes, in the thickness direction of the film, a region A containing an inorganic filler. Region A is formed of a thermosetting composition containing an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in the volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative (hereinafter, sometimes referred to as "inorganic filler A"). The thermosetting composition forming region A can contain a polymerizable compound and a thermal polymerization initiator.

[0041] The adhesive film for circuit connection of this embodiment can include, in the thickness direction of the film, a region S that does not contain conductive particles, and region A is provided in at least a part of region S. From the viewpoint of easily ensuring conduction between the opposed electrodes even during installation at low pressure, based on the range in the thickness direction of the film, the proportion of region A in region S can be 60% or more, 80% or more, or 100%.

[0042] The adhesive film for circuit connection of this embodiment can include, in the thickness direction of the film, a region P that further contains a cured product of a photocurable resin component, and conductive particles are dispersed in this region P.

[0043] Figure 1 is a schematic cross-sectional view showing an embodiment of the adhesive film for circuit connection of the present embodiment. Figure 1 (a) The adhesive film 1a for circuit connection shown (hereinafter, sometimes simply referred to as "adhesive film 1a".) includes: a first adhesive layer 2 containing conductive particles 4 and an adhesive component 5 including a cured product of a photocurable resin component and a (first) thermosetting resin component; and a second adhesive layer 3 provided on the first adhesive layer 2 and containing a (second) thermosetting resin component. And, Figure 1 (b) In the adhesive film 1b for circuit connection shown (hereinafter, sometimes simply referred to as "adhesive film 1b".), a third adhesive layer containing a (third) thermosetting resin component is laminated on the side of the first adhesive layer 2 opposite to the second adhesive layer 3, and other than that, it has the same structure as the adhesive film 1a.

[0044] Hereinafter, with reference to Figure 1 , the adhesive film for circuit connection of the present embodiment will be described.

[0045] In the adhesive films 1a and 1b, the conductive particles 4 are dispersed in the first adhesive layer 2. Therefore, the adhesive films 1a and 1b can be adhesive films for circuit connection having anisotropic conductivity (anisotropic conductive adhesive films). The adhesive films 1a and 1b can be interposed between a first circuit component having a first electrode and a second circuit component having a second electrode, and are used for thermocompression bonding of the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other.

[0046] <First Adhesive Layer>

[0047] The first adhesive layer 2 contains conductive particles 4 (hereinafter, sometimes referred to as "(A) component".), a cured product of a photocurable resin component (hereinafter, sometimes referred to as "(B) component".) and a thermosetting resin component (hereinafter, sometimes referred to as "(C) component".). The first adhesive layer 2 can be obtained, for example, by irradiating a composition layer formed from a composition containing (A) component, (B) component and (C) component with light energy, polymerizing the components contained in the (B) component, and curing the (B) component. The first adhesive layer 2 contains (A) component and an adhesive component 5 including a cured product of (B) component and (C) component. The cured product of (B) component can be a cured product obtained by completely curing (B) component, or can be a cured product obtained by partially curing (B) component. The (C) component is a component that can flow during circuit connection, for example, an uncured curable resin component.

[0048] (A) Component: Conductive Particles

[0049] Regarding the component (A), as long as it is a particle with conductivity, there is no particular limitation. It can be metal particles composed of metals such as Au, Ag, Pd, Ni, Cu, solder, etc., conductive carbon particles composed of conductive carbon, and the like. The component (A) can be a coated conductive particle having a core containing non-conductive materials such as glass, ceramics, plastics (such as polystyrene), etc. and a coating layer containing the above-mentioned metal or conductive carbon and coating the core. Among them, the component (A) preferably has a coated conductive particle having a core containing metal particles or plastics formed by a heat-fusible metal and a coating layer containing a metal or conductive carbon and coating the core. Such coated conductive particles can easily deform the cured product of the thermosetting resin component by heating or pressurization. Therefore, when electrically connecting electrodes to each other, the contact area between the electrode and the component (A) can be increased, and the conductivity between the electrodes can be further improved.

[0050] From the viewpoint of easily showing a low resistance to a circuit having a Ti surface, conductive particles capable of using conductive particles having a palladium plating can be used. At this time, a palladium plating can be provided on the outermost surface of the conductive particles. Specifically, conductive particles obtained by subjecting the surface of a plastic core body to a Ni plating and then subjecting the outermost surface to a replacement plating with Pd can be used. From the viewpoint of preventing short circuits between the conductive particles, such conductive particles can use conductive particles having insulating fine particles carried on their surfaces. From the viewpoint of more easily showing a low resistance, during the Ni plating process, a ceramic core material of 100 nm to 200 nm is incorporated into the plating, and then a Pd plating is performed. Insulating fine particles can be carried as needed.

[0051] (A) component may be an insulated coated conductive particle having the above-mentioned metal particles, conductive carbon particles or coated conductive particles and an insulating layer containing an insulating material such as resin and coating the surface of the particle. If the (A) component is an insulated coated conductive particle, even when the content of the (A) component is large, since an insulating layer is provided on the surface of the particle, the occurrence of short circuits caused by the contact between the (A) components can be suppressed, and the insulation between adjacent electrode circuits can also be improved. The (A) component can be used alone one of the above various conductive particles or used in combination of two or more kinds.

[0052] (A) The maximum particle size of the component needs to be smaller than the minimum spacing of the electrodes (the shortest distance between adjacent electrodes). From the viewpoints of excellent dispersibility and conductivity, the maximum particle size of the (A) component can be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more. From the viewpoints of excellent dispersibility and conductivity, the maximum particle size of the (A) component can be 20 μm or less, 10 μm or less, or 5 μm or less. In this specification, for any 300 (pcs) conductive particles, the particle size is measured by observation using a scanning electron microscope (SEM), and the maximum value obtained is taken as the maximum particle size of the (A) component. In addition, when the (A) component has protrusions or the like, or when the (A) component is not spherical, the particle size of the (A) component is taken as the diameter of the circle circumscribing the conductive particle in the SEM image.

[0053] From the viewpoints of excellent dispersibility and conductivity, the average particle size of the (A) component can be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more. From the viewpoints of excellent dispersibility and conductivity, the average particle size of the (A) component can be 20 μm or less, 10 μm or less, or 5 μm or less. In this specification, for any 300 (pcs) conductive particles, the particle size is measured by observation using a scanning electron microscope (SEM), and the average value of the particle sizes obtained is taken as the average particle size.

[0054] In the first adhesive layer 2, it is preferable that the (A) component is uniformly dispersed. From the viewpoint of obtaining a stable connection resistance, the particle density of the (A) component in the adhesive films 1a and 1b can be 100 particles / mm 2 or more, 1000 particles / mm 2 or more, 3000 particles / mm 2 or more, or 5000 particles / mm 2 or more. From the viewpoint of improving the insulation between adjacent electrodes, the particle density of the (A) component in the adhesive films 1a and 1b can be 100000 particles / mm 2 or less, 70000 particles / mm 2 or less, 50000 particles / mm 2 or less, or 30000 particles / mm 2 or less.

[0055] From the viewpoint of further improving conductivity, based on the total mass of the first adhesive layer, the content of component (A) can be 1% by mass or more, 5% by mass or more, or 10% by mass or more. From the viewpoint of easily suppressing short circuits, based on the total mass of the first adhesive layer, the content of component (A) can be 60% by mass or less, 50% by mass or less, or 40% by mass or less. If the content of component (A) is within the above range, the effects of the present invention tend to be significantly exhibited. In addition, the content of component (A) in the composition or the composition layer (based on the total mass of the composition or the composition layer) can be the same as the above range.

[0056] (B) component: photocurable resin component

[0057] Regarding the (B) component, as long as it is a resin component that cures by light irradiation, there is no particular limitation. However, from the viewpoint of more excellent connection resistance, it can be a resin component having radical curability. The (B) component can contain, for example, a radically polymerizable compound (hereinafter, sometimes referred to as "(B1) component") and a photo radical polymerization initiator (hereinafter, sometimes referred to as "(B2) component"). The (B) component can be a component composed of the (B1) component and the (B2) component.

[0058] (B1) component: radically polymerizable compound

[0059] (B1) component is a compound that undergoes radical polymerization by the radicals generated from the (B2) component upon irradiation with light (for example, ultraviolet light). The (B1) component can be either a monomer or a polymer (or oligomer) formed by polymerization of one or more monomers. Regarding the (B1) component, one kind can be used alone, or multiple kinds can be used in combination.

[0060] (B1) component is a compound having a radical polymerizable group that reacts by radicals. Examples of the radical polymerizable group include (meth)acryloyl group, vinyl group, allyl group, styryl group, alkenyl group, alkenylene group, maleimide group, etc. From the viewpoints of easily obtaining the desired melt viscosity after polymerization, further improving the effect of reducing the connection resistance, and more excellent connection reliability, the number of radical polymerizable groups (functional group numbers) possessed by the (B1) component can be 2 or more, and from the viewpoint of suppressing curing shrinkage during polymerization, it can be 10 or less. And, in order to maintain the balance between the crosslinking density and the curing shrinkage, in addition to the compounds having the number of radical polymerizable groups within the above range, compounds having the number of radical polymerizable groups outside the above range can also be used.

[0061] From the viewpoint of suppressing the flow of conductive particles, for example, the component (B1) may contain a polyfunctional (two or more functional groups) (meth)acrylate. The polyfunctional (two or more functional groups) (meth)acrylate may be a difunctional (meth)acrylate, and the difunctional (meth)acrylate may be a difunctional aromatic (meth)acrylate.

[0062] As polyfunctional (meth)acrylates, for example, there may be mentioned aliphatic (meth)acrylates such as 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, 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, 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, glycerol di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate; aromatic (meth)acrylates such as 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 di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane 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 and other aliphatic (meth)acrylates; aromatic epoxy (meth)acrylates such as bisphenol type epoxy (meth)acrylate, novolac type epoxy (meth)acrylate, cresol novolac type epoxy (meth)acrylate, etc.

[0063] From the viewpoint of both reducing the contact resistance and suppressing the particle flow, based on the total mass of the component (B1), the content of the polyfunctional (2 or more functional groups) (meth)acrylate may be, for example, 40 to 100% by mass, 50 to 100% by mass, or 60 to 100% by mass.

[0064] In addition to the polyfunctional (2 or more functional groups) (meth)acrylate, the component (B1) may further contain a monofunctional (meth)acrylate. Examples of the monofunctional (meth)acrylate include (meth)acrylic acid; (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid tert-butyl ester, (meth)acrylic acid butoxyethyl ester, (meth)acrylic acid isoamyl ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid heptyl ester, (meth)acrylic acid octylheptyl ester, (meth)acrylic acid nonyl ester, (meth)acrylic acid decyl ester, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropylene glycol (meth)acrylate, mono(2-(meth)acryloyloxyethyl) succinate and other aliphatic (meth)acrylates; 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-naphthyloxyethyl (meth)acrylate, 2-naphthyloxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthyloxy)propyl (meth)acrylate, 2-hydroxy-3-(2-naphthyloxy)propyl (meth)acrylate and other aromatic (meth)acrylates; (meth)acrylic acid glycidyl ester and other (meth)acrylates having an epoxy group, 3,4-epoxycyclohexylmethyl (meth)acrylate and other (meth)acrylates having an alicyclic epoxy group, (3-ethyloxetane-3-yl)methyl (meth)acrylate and other (meth)acrylates having an oxetanyl group, etc.

[0065] Based on the total mass of the component (B1), the content of the monofunctional (meth)acrylate may be, for example, 0 to 60% by mass, 0 to 50% by mass, or 0 to 40% by mass.

[0066] (B) component's cured product can, for example, have a polymerizable group that reacts through a mechanism other than free radicals. The polymerizable group that reacts through a mechanism other than free radicals can be, for example, a cationic polymerizable group that reacts through cations. As the cationic polymerizable group, for example, epoxy groups such as glycidyl group, alicyclic epoxy groups such as epoxycyclohexylmethyl group, oxetanyl groups such as ethyloxetanylmethyl group, etc. can be cited. The cured product of the (B) component having a polymerizable group that reacts through a mechanism other than free radicals can be introduced, for example, by using a (meth)acrylate having an epoxy group, a (meth)acrylate having an alicyclic epoxy group, a (meth)acrylate having an oxetanyl group, etc., which are (meth)acrylates having a polymerizable group that reacts through a mechanism other than free radicals, as the (B) component. From the viewpoint of improving reliability, the mass ratio of the (meth)acrylate having a polymerizable group that reacts through a mechanism other than free radicals to the total mass of the (B1) component (mass (loading amount) of the (meth)acrylate having a polymerizable group that reacts through a mechanism other than free radicals / total mass (loading amount) of the (B1) component) can be, for example, 0 to 0.7, 0 to 0.5, or 0 to 0.3.

[0067] (B1) component can contain other free radical polymerizable compounds in addition to polyfunctional (two or more functional groups) and monofunctional (meth)acrylates. As other free radical polymerizable compounds, for example, maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, nadimide derivatives, etc. can be cited. Based on the total mass of the (B1) component, the content of other free radical polymerizable compounds can be, for example, 0 to 40 mass%.

[0068] (B2) component: Photo radical polymerization initiator

[0069] (B2) component is a photo polymerization initiator that generates free radicals by irradiating light having a wavelength in the range of 150 to 750 nm, preferably in the range of 254 to 405 nm, and more preferably having a wavelength of 365 nm (for example, ultraviolet light). Regarding the (B2) component, one kind can be used alone, or multiple kinds can be used in combination.

[0070] (B2) component decomposes by light and generates free radicals. That is, the (B2) component is a compound that generates free radicals by applying light energy from the outside. The (B2) component can be a compound having a structure such as an oxime ester structure, a bisimidazole structure, an acridine structure, an α-aminoalkylbenzophenone structure, an aminobenzophenone structure, an N-phenylglycine structure, an acylphosphine oxide structure, a benzyldimethyl ketal structure, an α-hydroxyalkylbenzophenone structure, etc. Regarding the (B2) component, one kind can be used alone, or multiple kinds can be used in combination. From the viewpoints of easily obtaining the desired melt viscosity and more excellent reduction effect of the connection resistance, the (B2) component can be a compound having at least one structure selected from the group consisting of an oxime ester structure, an α-aminoalkylbenzophenone structure, and an acylphosphine oxide structure.

[0071] Specific examples of the compound having an oxime ester structure include 1-phenyl-1,2-butanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-o-benzoyl oxime, 1,3-diphenylpropanetrione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropanetrione-2-(o-benzoyl)oxime, 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(o-benzoyl oxime), acetophenone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyl oxime), etc.

[0072] Specific examples of the compound having an α-aminoalkylbenzophenone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(morpholinophenyl)-butan-1-one, etc.

[0073] Specific examples of the compound having an acylphosphine oxide structure include bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, etc.

[0074] From the viewpoint of suppressing the flow of conductive particles, the content of the (B2) component can be, for example, 0.1 to 10 parts by mass, 0.3 to 7 parts by mass, or 0.5 to 5 parts by mass with respect to 100 parts by mass of the (B1) component.

[0075] From the viewpoint of suppressing the flow of conductive particles, based on the total mass of the first adhesive layer, the content of the cured product of component (B) can be 1% by mass or more, 5% by mass or more, or 10% by mass or more. From the viewpoint of exhibiting low resistance in low-pressure mounting, based on the total mass of the first adhesive layer, the content of the cured product of component (B) can be 50% by mass or less, 40% by mass or less, or 30% by mass or less. In addition, the content of component (B) in the composition or composition layer used to form the first adhesive layer (based on the total mass of the composition or composition layer) can be the same as the above range.

[0076] (C) component: thermosetting resin component

[0077] (C) component may contain, for example, a cationically polymerizable compound (hereinafter, sometimes referred to as "(C1) component") and a thermal cationic polymerization initiator (hereinafter, sometimes referred to as "(C2) component"). (C) component may be a component composed of (C1) component and (C2) component. In addition, the first thermosetting resin component and the second thermosetting resin component respectively refer to the thermosetting resin components contained in the first adhesive layer and the second adhesive layer. The types, combinations, and contents of the components contained in the first thermosetting resin component and the second thermosetting resin component (for example, (C1) component, (C2) component, etc.) may be the same as each other or different from each other.

[0078] (C1) component: cationically polymerizable compound

[0079] (C1) component is a compound that crosslinks by reacting with (C2) component through heat. In addition, (C1) component is a compound that does not have a radically polymerizable group that reacts through free radicals, and (C1) component is not included in (B1) component. From the viewpoint of further improving the reduction effect of the connection resistance and more excellent connection reliability, (C1) component can be a compound having one or more ring-opening polymerizable cyclic ether groups in the molecule. Regarding (C1) component, one type can be used alone, or multiple types can be used in combination. As a compound having one or more ring-opening polymerizable cyclic ether groups in the molecule, for example, it can be at least one selected from the group consisting of oxetane compounds and alicyclic epoxy compounds. From the viewpoint of easily obtaining the desired melt viscosity, (C1) component preferably contains both at least one oxetane compound and at least one alicyclic epoxy compound.

[0080] As the oxetane compound of the component (C1), any compound that has an oxetanyl group and does not have a free-radical polymerizable group can be used without particular limitation. Examples of commercially available oxetane compounds include ETERNACOLL OXBP (trade name, manufactured by UBE Corporation), OXSQ, OXT-121, OXT-221, OXT-101, OXT-212 (trade names, manufactured by TOAGOSEI CO., LTD.), etc. These can be used alone as one compound or in combination of multiple compounds.

[0081] As the alicyclic epoxy compound of the component (C1), any compound that has an alicyclic epoxy group (e.g., epoxycyclohexyl) and does not have a free-radical polymerizable group can be used without particular limitation. Examples of commercially available alicyclic epoxy compounds include EHPE3150, EHPE3150CE, CELLOXIDE8010, CELLOXIDE2021P, CELLOXIDE2081 (trade names, manufactured by Daicel Corporation), etc. These can be used alone as one compound or in combination of multiple compounds.

[0082] (C2) component: Thermal cationic polymerization initiator

[0083] (C2) component is a thermal polymerization initiator that initiates polymerization by generating an acid or the like upon heating. (C2) component can be a salt compound composed of a cation and an anion. Regarding the (C2) component, for example, there can be mentioned sulfonium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, anilinium salts, etc. having anions such as 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 - , AsF 6 - , etc. These can be used alone as one or in combination of multiple.

[0084] From the viewpoint of storage stability, (C2) component can be, for example, a salt compound having an anion containing boron as a constituent element, that is, BF 4 - or BR 4 - (R represents a phenyl group substituted with two or more fluorine atoms or two or more trifluoromethyl groups.). The anion containing boron as a constituent element can be BR 4- , and more specifically, it can be tetra(pentafluorophenyl)borate.

[0085] Due to its resistance to substances that may hinder curing caused by cationic curing, the onium salt as the (C2) component can be, for example, an anilinium salt. As anilinium salt compounds, for example, N,N-dimethylanilinium salts, N,N-diethylanilinium salts, and other N,N-dialkylanilinium salts can be cited.

[0086] (C2) component can be an anilinium salt having an anion containing boron as a constituent element. As commercially available products of such salt compounds, for example, CXC-1821 (trade name, manufactured by King Industries, Inc.) can be cited.

[0087] From the viewpoint of ensuring the formability and curability of the adhesive film for forming the first adhesive layer, the content of the (C2) component can be, for example, 0.1 to 25 parts by mass, 1 to 20 parts by mass, 3 to 18 parts by mass, or 5 to 15 parts by mass relative to 100 parts by mass of the (C1) component.

[0088] From the viewpoint of ensuring the curability of the adhesive film for forming the first adhesive layer, based on the total mass of the first adhesive layer, the content of the (C) component can be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more. From the viewpoint of ensuring the formability of the adhesive film for forming the first adhesive layer, based on the total mass of the first adhesive layer, the content of the (C) component can be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less. In addition, the content of the (C) component in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) can be the same as the above range.

[0089] [Other components]

[0090] In addition to the cured products of the (A) component, (B) component, and (C) component, the first adhesive layer 2 can further contain other components. As other components, for example, thermoplastic resins (hereinafter sometimes referred to as “(D) components”), coupling agents (hereinafter sometimes referred to as “(E) components”), and filler materials (hereinafter sometimes referred to as “(F) components”) can be cited.

[0091] As the component (D), a resin that functions as a film-forming component can be used. For example, phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, acrylate rubber, epoxy resin (solid at 25°C), etc. can be cited. These can be used alone or in combination of multiple kinds. By further containing the component (D) in the composition containing the components (A), (B), and (C), a composition layer (and further the first adhesive layer 2) can be easily formed from the composition. Among them, the component (D) can be, for example, phenoxy resin.

[0092] From the viewpoint of resin excludability during installation, the weight-average molecular weight (Mw) of the component (D) can be, for example, 5000 to 200000, 10000 to 100000, 20000 to 80000, or 40000 to 60000. In addition, Mw refers to the value measured by gel permeation chromatography (GPC) and converted using a calibration curve based on standard polystyrene.

[0093] Based on the total mass of the first adhesive layer, the content of the component (D) can be 1% by mass or more, 5% by mass or more, 10% by mass or more, or 20% by mass or more, and can also be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less. In addition, the content of the component (D) in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) can be the same as the above range.

[0094] As the component (E), for example, silane coupling agents having organic functional groups such as (meth)acryloyl group, mercapto group, amino group, imidazole group, epoxy group, etc., silane compounds such as tetraalkoxysilane, tetraalkoxy titanate derivatives, polydialkyl titanate derivatives, etc. can be cited. These can be used alone or in combination of multiple kinds. By containing the component (E) in the first adhesive layer 2, the adhesiveness can be further improved. The component (E) can be, for example, a silane coupling agent. Based on the total mass of the first adhesive layer, the content of the component (E) can be 0.1 to 10% by mass. In addition, the content of the component (E) in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) can be the same as the above range.

[0095] As the component (F), for example, a non-conductive filler (e.g., non-conductive particles) can be cited. The component (F) can be either an inorganic filler or an organic filler. As the inorganic filler, for example, metal oxide fine particles such as silica fine particles, alumina fine particles, silica-alumina fine particles, titanium dioxide fine particles, zirconium dioxide fine particles, etc.; inorganic fine particles such as metal nitride fine particles can be cited. As the organic filler, for example, organic fine particles such as silicone fine particles, methacrylate / butadiene / styrene fine particles, acrylic / silicone fine particles, polyamide fine particles, polyimide fine particles, etc. These can be used alone or in combination of multiple kinds. Regarding the component (F), it can be appropriately formulated within the range that does not impair the effects of the present invention. Regarding the content of the component (F) in the composition for forming the first adhesive layer or the composition layer (based on the total mass of the composition or the composition layer), it can also be appropriately set within the range that does not impair the effects of the present invention.

[0096] [Other additives]

[0097] The first adhesive layer 2 may further contain other additives such as a softening agent, a promoter, an anti-degradant, a colorant, a flame retardant, a thixotropic agent, etc. Based on the total mass of the first adhesive layer, the content of the other additives can be, for example, 0.1 to 10% by mass. In addition, the content of the other additives in the composition for forming the first adhesive layer or the composition layer (based on the total mass of the composition or the composition layer) can be the same as the above range.

[0098] From the viewpoint that the conductive particles 4 are easily captured between the opposing electrodes and the connection resistance can be further reduced, the thickness d1 of the first adhesive layer 2 can be 0.1 times or more of the average particle diameter of the conductive particles 4, can also be 0.2 times or more, and can also be 0.3 times or more. From the viewpoint that when the conductive particles are sandwiched between the opposing electrodes during thermocompression bonding, the conductive particles are more easily flattened and the connection resistance can be further reduced, the thickness d1 of the first adhesive layer 2 can be 0.8 times or less of the average particle diameter of the conductive particles 4, can also be 0.7 times or less. From these viewpoints, the thickness d1 of the first adhesive layer 2 can be 0.1 to 0.8 times of the average particle diameter of the conductive particles 4, can also be 0.2 to 0.8 times, and can also be 0.3 to 0.7 times. In addition, the thickness d1 of the first adhesive layer 2 refers to the thickness of the first adhesive layer at the separated portion between the adjacent conductive particles 4, 4.

[0099] When the thickness d1 of the first adhesive layer 2 and the average particle diameter of the conductive particles 4 satisfy the above relationship, for example, as Figure 1As shown, a part of the conductive particles 4 in the first adhesive layer 2 may protrude from the first adhesive layer 2 toward the second adhesive layer 3 side. At this time, the boundary S between the first adhesive layer 2 and the second adhesive layer 3 is located at the separated part of the adjacent conductive particles 4, 4. The boundary S exists on the conductive particles along the surface of the conductive particles, whereby the conductive particles 4 in the first adhesive layer 2 may not protrude from the first adhesive layer 2 toward the second adhesive layer 3 side and satisfy the above relationship. The conductive particles 4 do not expose the surface 2a on the side of the first adhesive layer 2 opposite to the second adhesive layer 3 side, and the surface 2a on the opposite side may be a flat surface.

[0100] The relationship between the thickness d1 of the first adhesive layer 2 and the maximum particle size of the conductive particles 4 may be the same as above. For example, the thickness d1 of the first adhesive layer 2 may be 0.1 to 0.8 times, or 0.2 to 0.8 times, or 0.3 to 0.7 times the maximum particle size of the conductive particles 4.

[0101] The thickness d1 of the first adhesive layer 2 may be, for example, 5.0 μm or less. The thickness d1 of the first adhesive layer 2 may be 4.5 μm or less or 4.0 μm or less. Since the thickness d1 of the first adhesive layer 2 is 5.0 μm or less, the conductive particles at the time of circuit connection can be captured more efficiently. The thickness d1 of the first adhesive layer 2 may be, for example, 0.1 μm or more, 0.5 μm or more, or 0.7 μm or more. In addition, regarding the thickness d1 of the first adhesive layer 2, for example, it can be obtained by sandwiching an adhesive film with two glasses (thickness: about 1 mm), casting a resin composition composed of 100 g of bisphenol A type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of diethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.), then grinding the cross-section using a grinding machine, and measuring using a scanning electron microscope (SEM, trade name: SE-8010, manufactured by Hitachi High-Tech Science Corporation). And, as Figure 1 shown, in the case where a part of the conductive particles 4 exposes from the surface of the first adhesive layer 2 (for example, protrudes toward the second adhesive layer 3 side), the distance from the surface 2a on the side of the first adhesive layer 2 opposite to the second adhesive layer 3 side to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located at the separated part of the adjacent conductive particles 4, 4 (the distance represented by d1 in Figure 1 is the thickness of the first adhesive layer 2, and the exposed part of the conductive particles 4 is not included in the thickness of the first adhesive layer 2. The length of the exposed part of the conductive particles 4 may be, for example, 0.1 μm or more and may be 5.0 μm or less.

[0102] <Second Adhesive Layer>

[0103] The second adhesive layer 3 can contain component (C) and component (F). The components (C1) and (C2) used in the component (C) (i.e., the second thermosetting resin component) in the second adhesive layer 3 are the same as the components (C1) and (C2) used in the component (C) (i.e., the first thermosetting resin component) in the first adhesive layer 2, and thus detailed description thereof is omitted herein. The second thermosetting resin component may be the same as or different from the first thermosetting resin component.

[0104] From the viewpoint of maintaining reliability, based on the total mass of the second adhesive layer, the content of component (C) can be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more. From the viewpoint of preventing poor resin bleeding on a reel as a supply method, based on the total mass of the second adhesive layer, the content of component (C) can be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less.

[0105] The second adhesive layer 3 can contain an inorganic filler as component (F). From the viewpoint of sufficiently ensuring conduction between opposing electrodes of a circuit connection structure even when circuit components are connected to each other at a low pressure and sufficiently suppressing the generation of large indentations that are the main cause of defective determination by an automatic appearance inspection device, the second adhesive layer 3 can be formed of a thermosetting composition containing an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in a volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative.

[0106] As the inorganic filler, from the viewpoint of improving reliability, silica fillers such as silica fine particles can be used. Based on the total amount of the silica filler, the content of silica in the silica filler can be 99% by mass or more, or can be 100%.

[0107] Regarding the inorganic filler having the above volume-based particle size distribution, for example, it can be obtained by the following method: Prepare an inorganic filler containing inorganic particles having a primary particle size of 0.3 to 0.7 μm or an inorganic filler having a volume average particle size of 1.0 to 2.0 μm, and remove inorganic particles having a particle size of 2.0 μm or more by a known classification method such as filtration using air classification, filter paper, or a capsule filter.

[0108] From the viewpoint of easily ensuring fluidity, the D50 of the inorganic filler can be 0.5 to 1.0 μm, can be 0.6 to 0.9 μm, or can be 0.7 to 0.8 μm. Further, from the viewpoint of suppressing the generation of large indentations, the D95 of the inorganic filler can be 0.9 to 2.0 μm, can be 1.0 to 1.8 μm, or can be 1.1 to 1.6 μm.

[0109] From the viewpoint of easily ensuring conduction between the opposed electrodes even when mounted under low pressure and ensuring the film property as a strip product, based on the total mass of the second adhesive layer or the thermosetting composition, the content of the inorganic filler in the second adhesive layer 3 or the thermosetting composition forming the second adhesive layer 3 can be 10 to 70% by mass, can be 20 to 60% by mass, or can be 30 to 50% by mass.

[0110] The second adhesive layer 3 may further contain other components and other additives in the first adhesive layer 2. The preferred modes of the other components and other additives are the same as those of the first adhesive layer 2.

[0111] Based on the total mass of the second adhesive layer, the content of the component (D) can be 1% by mass or more, 5% by mass or more, or 10% by mass or more, and can be 80% by mass or less, 60% by mass or less, or 40% by mass or less.

[0112] Based on the total mass of the second adhesive layer, the content of the component (E) can be 0.1 to 10% by mass.

[0113] Based on the total mass of the second adhesive layer, the content of other additives can be, for example, 0.1 to 10% by mass.

[0114] The thickness d2 of the second adhesive layer 3 can be appropriately set according to the height of the electrodes of the circuit components to be bonded, etc. From the viewpoint of being able to sufficiently fill the space between the electrodes to seal the electrodes and obtaining better connection reliability, the thickness d2 of the second adhesive layer 3 can be 5 μm or more or 7 μm or more, and can be 15 μm or less or 11 μm or less. Further, the thickness d2 of the second adhesive layer 3 can be obtained, for example, by the same method as the method for measuring the thickness d1 of the first adhesive layer 2. And, in the case where a part of the conductive particles 4 protrudes from the surface of the first adhesive layer 2 (for example, protrudes toward the second adhesive layer 3 side), the distance from the surface 3a on the side opposite to the first adhesive layer 2 side in the second adhesive layer 3 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 at the separated part of the adjacent conductive particles 4, 4 (the distance represented by d2 in Figure 1 is the thickness of the second adhesive layer 3.

[0115] The third adhesive layer 6 can contain component (C). The components (C1) and (C2) used in the component (C) (i.e., the third thermosetting resin component) in the third adhesive layer are the same as the components (C1) and (C2) used in the component (C) (i.e., the first thermosetting resin component) in the first adhesive layer 2, so detailed description is omitted here. The third thermosetting resin component can be the same as or different from the first thermosetting resin component. The third thermosetting resin component can be the same as or different from the second thermosetting resin component.

[0116] From the viewpoint of imparting good transferability and peel resistance, based on the total mass of the third adhesive layer, the content of component (C) can be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more. From the viewpoint of imparting good half-cutability and anti-blocking property (inhibiting resin bleeding of the reel), based on the total mass of the third adhesive layer, the content of component (C) can be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less.

[0117] The third adhesive layer can further contain other components and other additives in the first adhesive layer 2.

[0118] Based on the total mass of the third adhesive layer, the content of component (D) can be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and can also be 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0119] Based on the total mass of the third adhesive layer, the content of component (E) can be 0.1 to 10% by mass.

[0120] (F) The content of the component can be appropriately set within the range that does not impair the effects of the present invention.

[0121] Based on the total mass of the third adhesive layer, the content of other additives can be, for example, 0.1 to 10% by mass.

[0122] The thickness of the third adhesive layer can be appropriately set according to the minimum melt viscosity of the adhesive film, the height of the electrodes of the circuit components to be bonded, etc. The thickness of the third adhesive layer is preferably smaller than the thickness d2 of the second adhesive layer 3. From the viewpoint of being able to sufficiently fill the space between the electrodes to seal the electrodes and obtaining better connection reliability, the thickness of the third adhesive layer can be 0.2 μm or more and can also be 3.0 μm or less. In addition, the thickness of the third adhesive layer can be obtained, for example, by the same method as the method for measuring the thickness d1 of the first adhesive layer 2.

[0123] The thickness of the adhesive films 1a and 1b (the total thickness of all the layers constituting the adhesive films 1a and 1b,Figure 1 (a) The sum of the thickness d1 of the first adhesive layer 2 and the thickness d2 of the second adhesive layer 3, and in Figure 1 (b) The sum of the thickness d1 of the first adhesive layer 2, the thickness d2 of the second adhesive layer 3, and the thickness of the third adhesive layer) may be, for example, 5 μm or more or 8 μm or more, and may also be 30 μm or less or 20 μm or less.

[0124] In the adhesive films 1a and 1b, for example, the first adhesive layer may be the above-mentioned region P. At this time, the range in the thickness direction of the film in region P can be made the same as the thickness d1 of the first adhesive layer 2 described above. Region P can be formed from the composition obtained by removing the conductive particles from the above-mentioned composition for forming the first adhesive layer.

[0125] In the adhesive films 1a and 1b, for example, the second adhesive layer may be the above-mentioned region A.

[0126] When the second adhesive layer is region A, the range in the thickness direction of the film in region A can be made the same as the thickness d2 of the second adhesive layer 3 described above. Region A can be formed from the above-mentioned composition for forming the second adhesive layer.

[0127] In the adhesive films 1a and 1b, the second adhesive layer or the second adhesive layer and the third adhesive layer may be the region S that does not contain conductive particles. Region S can be formed from the above-mentioned composition for forming the second adhesive layer and the composition for forming the third adhesive layer.

[0128] In the adhesive films 1a and 1b, inorganic fillers with a particle size D50 at 50% cumulative in the volume-based particle size distribution of 0.5 to 1.0 μm and a particle size D95 at 95% cumulative of 0.9 to 2.0 μm may be included in the second adhesive layer and not included in the first adhesive layer and the third adhesive layer.

[0129] The minimum melt viscosity of the adhesive films 1a and 1b is 450 to 1600 Pa·s. The minimum melt viscosity of the adhesive films 1a and 1b can be 500 Pa·s or more, 600 Pa·s or more, 700 Pa·s or more, or 800 Pa·s or more. If the minimum melt viscosity of the adhesive films 1a and 1b is 450 Pa·s or more, deformation of the plastic substrate during thermocompression bonding can be suppressed, and occurrence of circuit disconnection can be prevented. The minimum melt viscosity of the adhesive films 1a and 1b can be 1500 Pa·s or less, 1400 Pa·s or less, 1300 Pa·s or less, 1200 Pa·s or less, 1100 Pa·s or less, or 1000 Pa·s or less. If the minimum melt viscosity of the adhesive films 1a and 1b is 1600 Pa·s or less, a decrease in the expulsibility of the resin during circuit connection can be suppressed, and thus the connection resistance between the opposing electrodes of the circuit connection structure can be reduced, and good conduction characteristics can be ensured. In addition, the minimum melt viscosity of the adhesive film can be obtained, for example, by the following method.

[0130] (Method for measuring the minimum melt viscosity)

[0131] The adhesive films were laminated with a laminator so that the thickness became 200 μm or more to obtain a laminate. The PET that had been demolded was peeled off from the obtained laminate and cut into 10.0 mm × 10.0 mm to obtain a measurement specimen. The minimum melt viscosity of the obtained measurement specimen was measured using a viscoelasticity measuring device (trade name: ARES-G2, manufactured by TA Instruments, heating rate: 10°C / min).

[0132] In the adhesive films 1a and 1b, the second adhesive layer 3 generally has a thickness thicker than that of the first adhesive layer 2. Therefore, the minimum melt viscosity of the adhesive films 1a and 1b tends to vary depending on the second adhesive layer 3. The adjustment of the minimum melt viscosity of the adhesive films 1a and 1b can be performed, for example, by adjusting the type, content, etc. of the constituent components (especially component (D)) contained in the second adhesive layer 3. And regarding the minimum melt viscosity of the adhesive films 1a and 1b, for example, it can also be adjusted by blending the above-mentioned inorganic filler A as component (F). By blending the inorganic filler A in the second adhesive layer 3, generation of large indentations can be sufficiently suppressed while reducing the minimum melt viscosity.

[0133] In the adhesive films 1a and 1b, the conductive particles 4 are dispersed in the first adhesive layer 2. Therefore, the adhesive films 1a and 1b are anisotropic conductive adhesive films having anisotropic conductivity. The adhesive films 1a and 1b are used to be interposed between a first circuit component having a first electrode and a second circuit component having a second electrode, and thermocompression bond the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other.

[0134] According to the adhesive films 1a and 1b, by setting the second adhesive layer 3 as the region A, even when the circuit components are connected to each other with a low pressure, conduction between the opposing electrodes of the circuit connection structure can be ensured, and generation of large indentations, which are the main cause of defective determination by an automatic appearance inspection device, can be sufficiently suppressed.

[0135] The adhesive film for circuit connection of the present embodiment can be applied to COP mounting. More specifically, it can be applied to the connection between a plastic substrate formed with circuit electrodes (for example, electrodes containing Ti) in an organic EL display and an IC chip such as a driving IC.

[0136] <Manufacturing Method of Adhesive Film for Circuit Connection>

[0137] A manufacturing method of an adhesive film for circuit connection according to an embodiment may include, for example: a step (first step) of irradiating a composition layer formed of a composition containing component (A), component (B), and component (C) (first thermosetting resin component), and other components as needed, to form a first adhesive layer; and a step (second step) of laminating a second adhesive layer containing component (C) (second thermosetting resin component) and inorganic filler A, and other components as needed, on the first adhesive layer. This manufacturing method may further include the following step (third step): laminating a third adhesive layer containing component (C) (third thermosetting resin component), and inorganic filler A and other components as needed, on the side of the first adhesive layer opposite to the second adhesive layer. At this time, the second step may be performed first, or the third step may be performed first. When the third step is performed first, the third adhesive layer is laminated on the side of the first adhesive layer opposite to the side where the second adhesive layer is to be laminated. Figure 2 It is a schematic cross-sectional view showing the manufacturing method including the above steps.

[0138] In the first step, for example, first, a composition containing component (A), component (B), component (C), and additives added as needed is stirred, mixed, kneaded, etc. in an organic solvent to dissolve or disperse it, thereby preparing a varnish composition (a varnish-like first adhesive composition). Then, using an air knife coater, a roll coater, an applicator, a chamfered wheel coater, a die coater, etc., after coating the varnish composition on a substrate that has been subjected to a release treatment, the organic solvent is volatilized by heating to form a composition layer formed by the composition on the substrate. At this time, by adjusting the coating amount of the varnish composition, the thickness of the finally obtained first adhesive layer (first adhesive film) can be adjusted. Then, light is irradiated on the composition layer formed by the composition to cure component (B) in the composition layer, and a first adhesive layer is formed on the substrate. The first adhesive layer can be referred to as a first adhesive film. The first step can be used to prepare Figure 2 The first adhesive layer 2 provided on the substrate 22 shown in (a).

[0139] Regarding the organic solvent used in the preparation of the varnish composition, there is no particular limitation as long as it has the property of being able to uniformly dissolve or disperse each component. As such an organic solvent, for example, toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, etc. can be cited. These organic solvents can be used alone or in combination of two or more. The stirring, mixing, or kneading during the preparation of the varnish composition can be carried out, for example, using a stirrer, a mortar machine, a three-roll mill, a ball mill, a bead mill, a homogenizing disperser, etc.

[0140] Regarding the substrate, there is no particular limitation as long as it has heat resistance capable of withstanding the heating conditions when the organic solvent is volatilized. As such a substrate, for example, a substrate (such as a film) formed of stretched polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene / vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber-based, liquid crystal polymer, etc. can be used.

[0141] The heating conditions when the organic solvent is volatilized from the varnish composition coated on the substrate can be appropriately set according to the organic solvent used, etc. The heating conditions can be, for example, 40 to 120 °C and 0.1 to 10 minutes.

[0142] A part of the solvent can remain in the first adhesive layer without being removed. Based on the total mass of the first adhesive layer, the content of the solvent in the first adhesive layer can be, for example, 10% by mass or less.

[0143] Further, based on the total of the component (A) of the varnish composition and the components other than the organic solvent, the content of the component (B) in the varnish composition may be 10% by mass or more and less than 60% by mass. At this time, it is easy to obtain the effect of suppressing the flow of the conductive particles, and it is easy to perform coating while maintaining a good appearance.

[0144] In the light irradiation in the curing process, it is preferable to use irradiation light (for example, ultraviolet light) having a wavelength in the range of 150 to 750 nm. Regarding the light irradiation, 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, etc. can be used. The cumulative light amount of the light irradiation can be appropriately set, but for example, it can be 500 to 3000 mJ / cm 2 .

[0145] The second step is a step of laminating a second adhesive layer on the first adhesive layer. In the second step, for example, first, the component (C), the inorganic filler A, and no light irradiation are used, and in other respects, in the same manner as in the first step, a second adhesive layer is formed on the substrate to obtain a second adhesive film. For example, it is possible to prepare Figure 2 the second adhesive layer 3 provided on the substrate 20 shown in (a). Then, by laminating the first adhesive film and the second adhesive film, the second adhesive layer can be laminated on the first adhesive layer (refer to Figure 2 (a) and (b)). Further, in the second step, for example, a varnish composition (varnish-like second adhesive composition) obtained by using the component (C), the inorganic filler A, and other additives added as needed is coated on the first adhesive layer, and the organic solvent is volatilized, whereby the second adhesive layer can also be laminated on the first adhesive layer.

[0146] As a method of laminating the first adhesive film and the second adhesive film, for example, methods such as hot pressing, roll lamination, and vacuum lamination can be cited. Regarding the lamination, for example, it can be performed under a temperature condition of 0 to 80°C.

[0147] A part of the solvent may not be removed and may remain in the second adhesive layer. Based on the total mass of the second adhesive layer, the content of the solvent in the second adhesive layer can be, for example, 10% by mass or less.

[0148] The third step is a step of laminating a third adhesive layer on the side of the first adhesive layer opposite to the second adhesive layer. In the third step, for example, first, in the same manner as in the second step, a third adhesive layer is formed on the substrate to obtain a third adhesive film. For example, it is possible to prepare Figure 2The third adhesive layer 6 provided on the substrate 24 as shown in (c). Next, the third adhesive film is bonded to the side of the first adhesive film opposite to the second adhesive film, whereby the third adhesive layer can be laminated on the side of the first adhesive layer opposite to the second adhesive layer (refer to Figure 2 (c)). Further, in the third step, for example, in the same manner as in the second step, a varnish composition (varnish-like third adhesive composition) is applied to the side of the first adhesive layer opposite to the second adhesive layer, and the organic solvent is volatilized, whereby the third adhesive layer can also be laminated on the first adhesive layer. The bonding method and its conditions are the same as those in the second step.

[0149] A part of the solvent may remain in the third adhesive layer without being removed. Based on the total mass of the third adhesive layer, the content of the solvent in the third adhesive layer may be, for example, 10% by mass or less.

[0150] <Inorganic filler-containing composition>

[0151] The inorganic filler-containing composition of the present embodiment contains an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in the volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative. The same inorganic filler as the above-mentioned inorganic filler A can be used as the inorganic filler.

[0152] The inorganic filler-containing composition of the present embodiment can be used to form an inorganic filler-containing region in a circuit connection component containing conductive particles and an inorganic filler. As the circuit connection component, the above-mentioned circuit connection adhesive film can be cited. According to the inorganic filler-containing composition of the present embodiment, as the inorganic filler-containing region, the above-mentioned region A and the second adhesive layer can be formed.

[0153] The composition of the inorganic filler-containing composition of the present embodiment can be set in the same manner as the composition in the above-mentioned second adhesive layer. For example, the composition may further contain a thermoplastic resin.

[0154] The inorganic filler-containing composition of the present embodiment may be a varnish composition (varnish-like inorganic filler-containing composition) containing the above-mentioned organic solvent.

[0155] The inorganic filler-containing composition of the present embodiment can be used to form an adhesive layer having a thickness of 10 μm or less, 9 to 4 μm, or 8 to 5 μm. According to the inorganic filler-containing composition of the present embodiment, even when coated with such a designed thickness, appearance defects such as scratches are less likely to occur, and a high coating yield can be obtained.

[0156] <Circuit connection structure and its manufacturing method>

[0157] Hereinafter, a circuit connection structure using the above-described adhesive film 1a for circuit connection as a circuit connection material and a method for manufacturing the same will be described.

[0158] Figure 3 It is a schematic cross-sectional view showing an embodiment of a circuit connection structure. As Figure 3 shown, the circuit connection structure 10 includes: a first circuit component 13 having a first electrode 12 formed on a first circuit board 11 and a main surface 11a of the first circuit board 11; a second circuit component 16 having a second electrode 15 formed on a second circuit board 14 and a main surface 14a of the second circuit board 14; and a circuit connection portion 17 disposed between the first circuit component 13 and the second circuit component 16 to electrically connect the first electrode 12 and the second electrode 15 to each other.

[0159] The first circuit component 13 and the second circuit component 16 may be the same as each other or different from each other. The first circuit component 13 and the second circuit component 16 may be a glass substrate or a plastic substrate formed with circuit electrodes; a printed wiring board; a ceramic wiring board; a flexible wiring board; an IC chip such as a driving IC, etc. The first circuit board 11 and the second circuit board 14 may be formed of inorganic substances such as semiconductors, glass, and ceramics, organic substances such as polyimide and polycarbonate, composites such as glass / epoxy, etc. The first circuit board 11 may be a plastic substrate. The first circuit component 13 may be, for example, a plastic substrate formed with circuit electrodes (a plastic substrate formed of an organic substance such as polyimide, polycarbonate, polyethylene terephthalate, or cycloolefin polymer), and the second circuit component 16 may be, for example, an IC chip such as a driving IC. The plastic substrate formed with electrodes may be formed by regularly arranging, for example, organic TFTs or a plurality of organic EL elements R, G, B in a matrix on the plastic substrate to form a display region.

[0160] The first electrode 12 and the second electrode 15 may be electrodes containing metals such as gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, titanium, etc., oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), etc. The first electrode 12 and the second electrode 15 may be electrodes formed by laminating two or more of these metals, oxides, etc. The electrode formed by laminating two or more may be two or more layers, or may be three or more layers. In the case where the first circuit component 13 is a plastic substrate, the first electrode 12 may be an electrode containing Ti, and more specifically, an electrode having a titanium layer on the outermost surface. The first electrode 12 and the second electrode 15 may be circuit electrodes or bump electrodes. At least one of the first electrode 12 and the second electrode 15 may be a bump electrode. In Figure 3 it, the first electrode 12 is a circuit electrode and the second electrode 15 is a bump electrode.

[0161] The circuit connection part 17 contains the cured product of the above-mentioned adhesive film 1a. The circuit connection part 17 can be formed of the cured product of the above-mentioned adhesive film 1a. For example, the circuit connection part 17 has: a first region 18, which is located on the side of the first circuit component 13 in the direction in which the first circuit component 13 and the second circuit component 16 face each other (hereinafter referred to as the "opposing direction"), and is formed of the cured product of the component (B) other than the conductive particles 4 in the above-mentioned first adhesive layer and the cured product of the component (C), etc.; a second region 19, which is located on the side of the second circuit component 16 in the opposing direction, and is formed of the cured product of the component (C), etc. in the above-mentioned second adhesive layer; and the conductive particles 4, which are at least interposed between the first electrode 12 and the second electrode 15 to electrically connect the first electrode 12 and the second electrode 15 to each other. As Figure 3 shown, the circuit connection part 17 does not have to have two distinct regions between the first region 18 and the second region 19, and a single region can be formed by mixing the cured product derived from the first adhesive layer and the cured product derived from the second adhesive layer.

[0162] In the circuit connection structure, one of the first circuit component and the second circuit component can be an IC chip, and the other can be a plastic substrate having an electrode containing Ti. Regarding the circuit connection structure, for example, there can be cited a flexible organic electroluminescent color display (organic EL display) formed by connecting a plastic substrate on which organic EL elements are regularly arranged to a drive circuit element as an image display driver, a touch panel formed by connecting a plastic substrate on which organic EL elements are regularly arranged to a position input element such as a touch panel, etc. The circuit connection structure can be applied to various monitors such as smartphones, tablet computers, televisions, navigation systems for vehicles, wearable terminals, etc.; furniture; home appliances; daily necessities, etc.

[0163] Figure 4 It is a schematic cross-sectional view showing an embodiment of a manufacturing method of a circuit connection structure. Figure 4 (a) and Figure 4 (b) are schematic cross-sectional views showing each process. As Figure 4 shown, the manufacturing method of the circuit connection structure 10 includes the following process: interposing the above-mentioned adhesive film 1a between the first circuit component 13 having the first electrode 12 and the second circuit component 16 having the second electrode 15, and performing thermocompression bonding on the first circuit component 13 and the second circuit component 16 to electrically connect the first electrode 12 and the second electrode 15 to each other.

[0164] Specifically, as Figure 4As shown in Fig. (a), first, a first circuit component 13 having a first electrode 12 formed on a first circuit board 11 and a main surface 11a of the first circuit board 11, and a second circuit component 16 having a second electrode 15 formed on a second circuit board 14 and a main surface 14a of the second circuit board 14 are prepared.

[0165] Next, the first circuit component 13 and the second circuit component 16 are arranged such that the first electrode 12 and the second electrode 15 face each other, and an adhesive film 1a is arranged between the first circuit component 13 and the second circuit component 16. For example, as Figure 4 shown in Fig. (a), the side of the first adhesive layer 2 is opposed to the main surface 11a of the first circuit board 11, and the adhesive film 1a is laminated on the first circuit component 13. Next, the second circuit component 16 is arranged on the first circuit component 13 on which the adhesive film 1a is laminated such that the first electrode 12 on the first circuit board 11 and the second electrode 15 on the second circuit board 14 face each other.

[0166] And, as Figure 4 shown in Fig. (b), while heating the first circuit component 13, the adhesive film 1a, and the second circuit component 16, pressure is applied to the first circuit component 13 and the second circuit component 16 in the thickness direction, thereby thermocompression bonding the first circuit component 13 and the second circuit component 16 to each other. At this time, in Figure 4 Fig. (b), as shown by the arrow, since the second adhesive layer 3 has an uncured thermosetting component that can flow, it flows in a manner that fills the gaps between the second electrodes 15 and is cured by the above heating. As a result, the first electrode 12 and the second electrode 15 are electrically connected to each other via the conductive particles 4, and the first circuit component 13 and the second circuit component 16 are bonded to each other, thereby obtaining the Figure 3 circuit connection structure 10 shown in Fig. In the manufacturing method of the circuit connection structure 10 of the present embodiment, it can be said that a part of the first adhesive layer 2 is cured by light irradiation, so the flow of the conductive particles in the first adhesive layer 2 is suppressed, and the first adhesive layer 2 hardly flows during the above thermocompression bonding, and the conductive particles are efficiently captured between the opposed electrodes. Therefore, the connection resistance between the opposed first electrode 12 and the second electrode 15 can be reduced. And if the thickness of the first adhesive layer is 5 μm or less, it tends to be able to capture the conductive particles during circuit connection more efficiently.

[0167] And, by containing the above inorganic filler A in the second adhesive layer 3, high fluidity is obtained, the connection resistance between the opposed first electrode 12 and the second electrode 15 can be reduced, and the generation of large indentations can be sufficiently suppressed.

[0168] The heating temperature during thermocompression bonding can be appropriately set, for example, it can be 50 to 190°C. Regarding the pressure, as long as it is within the range that does not damage the adherend, there is no particular limitation. However, in the case of COP mounting, for example, the pressure in terms of area conversion on the bump electrode can be 0.1 to 50 MPa, it can also be 40 MPa or less, and it can further be 0.1 to 40 MPa. And in the case of COG mounting, for example, the pressure in terms of area conversion on the bump electrode can be 10 to 100 MPa. These heating and pressurization times can be within the range of 0.5 to 120 seconds.

[0169] Examples

[0170] Hereinafter, examples are given to explain the present invention more specifically. However, the present invention is not limited to these examples.

[0171] [Fabrication of the First Adhesive Layer, the Second Adhesive Layer, and the Third Adhesive Layer]

[0172] In the fabrication of the first adhesive layer, the second adhesive layer, and the third adhesive layer, the materials shown below were used.

[0173] <Fabrication of Conductive Particles>

[0174] An 80-nm Ni plating was applied to the surface of a 3-μm plastic core, and a replacement plating with Pd was performed on the outermost 20 nm. Thus, conductive particles with an average particle diameter of 3.2 μm were obtained.

[0175] (A) Component: Conductive Particles

[0176] A-1: Conductive particles fabricated as described above

[0177] (B) Component: Photo-curable Resin Component

[0178] (B1) Component: Free Radical Polymerizable Compound

[0179] B1-1: NK Ester A-BPEF70T (ethoxylated fluorene type bis(meth)acrylate (2-functional), manufactured by SHIN-NAKAMURA CHEMICAL CO,LTD.), a substance diluted with toluene to a non-volatile component of 70 mass% was used

[0180] B1-2: RIPOXY VR-90 (bisphenol A type epoxy (meth)acrylate (2-functional) (vinyl ester resin), manufactured by SHOWA DENKO K.K.)

[0181] (B2) Component: Photo Radical Polymerization Initiator

[0182] B2-1: Irgacure OXE-02 (Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetoxime), manufactured by BASF), a substance diluted with MEK to a non-volatile content of 10% by mass

[0183] (C) Component: Thermosetting resin component

[0184] (C1) Component: Cationic polymerizable compound

[0185] C1-1: ETERNACOLL OXBP (3-ethyl-3-hydroxymethyloxetane, manufactured by UBE Corporation)

[0186] C1-2: EHPE3150 (Adduct of 1,2-epoxy-4-(2-epoxyethyl)cyclohexane with 2,2-bis(hydroxymethyl)-1-butanol, manufactured by Daicel Corporation)

[0187] C1-3: CELLOXIDE2021P (3,4-Epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate, manufactured by Daicel Corporation)

[0188] C1-4: OXSQ-TX100 (Derivative of poly({3-[(3-ethyl-3-oxetanylmethoxy)propyl}silsesquioxane), manufactured by TOAGOSEI CO., LTD.)

[0189] C1-5: CELLOXIDE8010 (Bis-7-oxabicyclo[4.1.0]heptane, manufactured by Daicel Corporation)

[0190] (C2) Component: Thermal cationic polymerization initiator

[0191] C2-1: CXC-1821 (manufactured by King Industries, Inc.)

[0192] (D) Component: Thermoplastic resin

[0193] D-1: PhenoTohto YP-50S (Bisphenol A type phenoxy resin, weight average molecular weight: 60,000, glass transition temperature: 84 °C, manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), a substance diluted with MEK to a non-volatile content of 40% by mass

[0194] D-2: TOPR-300 (high Tg type epoxy resin, epoxy equivalent: 900 to 1,000, softening point: 120 °C, manufactured by NIPPON STEEL Chemical&Material Co.,Ltd.), a substance diluted with MEK to a non-volatile component of 60 mass%

[0195] D-3: PhenoTohto FX-293 (fluorene skeleton-containing phenoxy resin, weight average molecular weight: 45,000, glass transition temperature: 158 °C, manufactured by NIPPON STEEL Chemical&Material Co.,Ltd.), a substance diluted with MEK to a non-volatile component of 60 mass%

[0196] D-4: PhenoTohto ZX-1356-2 (bisphenol A type and bisphenol F type copolymerized phenoxy resin, weight average molecular weight: 70000, glass transition temperature: 71 °C, manufactured by NIPPON STEEL Chemical&Material Co.,Ltd.), a substance diluted with MEK to a non-volatile component of 40 mass%

[0197] (E) component: coupling agent

[0198] E-1: SH-6040 (3-glycidoxypropyltrimethoxysilane, manufactured by Dow Corning TorayCo.,Ltd.)

[0199] (F) component: filler

[0200] (F1) component: inorganic filler

[0201] F-1: ADMAFINE SE2050 (silica filler, manufactured by Admatechs Company Limited), after reducing particles of 1 μm or more as much as possible by air classification, a substance diluted with MEK to a non-volatile component of 70 mass%

[0202] F-2: ADMAFINE SE2050 (silica filler, manufactured by Admatechs Company Limited), a substance diluted with MEK to a non-volatile component of 70 mass%

[0203] F-3: ADMANANO YA050C (silica filler, manufactured by Admatechs Company Limited), a substance diluted with MEK to a non-volatile component of 50 mass%

[0204] F-4: AEROSIL R805 (silica filler, manufactured by Evonik Industries AG), a substance diluted with MEK to a non-volatile content of 10% by mass

[0205] <Measurement of Particle Size Distribution of Inorganic Filler - 1>

[0206] The particle diameters D50 (particle diameter at 50% cumulative in the volume-based particle size distribution of the above inorganic filler) and D95 (particle diameter at 95% cumulative) were measured. In the measurement, Microtorac MT3300EXII manufactured by Nikkiso Co., Ltd. was used as the measuring device, and methyl ethyl ketone was used as the measuring solvent.

[0207] [Table 1]

[0208]

[0209] <Production of the First Adhesive Layer>

[0210] After obtaining a composition by mixing the materials shown in Table 2 at the composition ratio (mass ratio) shown in Table 2 (the values in Table 2 refer to the amount of non-volatile components), it was coated while applying a magnetic field on a PET (polyethylene terephthalate) film that had been subjected to a release treatment, and the organic solvent, etc. was hot air dried at 70°C for 5 minutes, thereby obtaining composition layers formed from the compositions containing each component respectively. The composition layers were coated so that the dried thicknesses became 3 - 4 μm respectively. Then, light irradiation (UV irradiation: metal halide lamp, cumulative light amount: 2100 mJ / cm 2 ) was performed on the composition layers respectively, thereby producing the first adhesive layer in which conductive particles were dispersed. Here, the thickness was measured using a contact thickness gauge.

[0211] In addition, when the thickness of the layer formed from the first adhesive composition or the adhesive layer is smaller than the thickness (diameter) of the conductive particles, if the thickness of the layer is measured using a contact thickness gauge, the thickness of the conductive particles is reflected and the thickness of the region where the conductive particles are present is measured. Therefore, after producing an adhesive film having a double-layer structure in which the first adhesive layer and the second adhesive layer are laminated, the thickness of the first adhesive layer at the separated portion between adjacent conductive particles was measured using a scanning electron microscope by the method described later.

[0212] [Table 2]

[0213]

[0214] <Production of the Second Adhesive Layer>

[0215] After obtaining a composition by mixing the materials shown in Table 3 at the composition ratio (mass ratio) shown in Table 3 (the values in Table 3 refer to the amount of non-volatile components), it was coated on a demolded PET (polyethylene terephthalate) film, and organic solvents, etc. were hot air dried at 70°C for 5 minutes, whereby the second adhesive layer formed from the composition containing each component was produced respectively. The adhesive layer was coated so that the thickness after drying became 8 to 9 μm. Here, the thickness was measured using a contact thickness gauge.

[0216] (Coating yield)

[0217] Regarding the coating yield when forming the second adhesive layer, the ratio Y (%) without white lines and scratches was determined, and the evaluation was carried out according to the following criteria.

[0218] A+: Y is 95% or more

[0219] A: Y is 90% or more and less than 95%

[0220] B: Y is 80% or more and less than 90%

[0221] C: Y is less than 80%

[0222] [Table 3]

[0223]

[0224] <Measurement of particle size distribution of inorganic filler - 2>

[0225] Regarding the inorganic filler (a mixture of 80 parts by mass of F-1 and 5 parts by mass of F-3) contained in Composition S1-4, the particle diameter D50 (particle diameter at 50% cumulative in the volume-based particle size distribution) and the particle diameter D95 (particle diameter at 95% cumulative) were measured in the same manner as above.

[0226] [Table 4]

[0227]

[0228] <Production of the third adhesive layer>

[0229] After obtaining a composition by mixing the materials shown in Table 5 at the composition ratio (mass ratio) shown in Table 5 (the values in Table 5 refer to the amount of non-volatile components), it was coated on a demolded PET (polyethylene terephthalate) film, and organic solvents, etc. were hot air dried at 70°C for 5 minutes, whereby the third adhesive layer formed from the composition containing each component was produced. The adhesive layer was coated so that the thickness after drying became 0.5 to 1.5 μm. Here, the thickness was measured using a contact thickness gauge.

[0230] [Table 5]

[0231]

[0232] (Examples 1 to 5 and Comparative Examples 1 to 5)

[0233] [Production of Adhesive Film]

[0234] The adhesive films having the structures shown in Table 6 were produced using the above-produced first adhesive layer, second adhesive layer, and third adhesive layer. For example, in the adhesive film of Example 1, while applying a temperature of 50 to 60°C, the first adhesive layer formed from Composition P-1 was laminated on the second adhesive layer formed from Composition S1-1, and the PET film on the first adhesive layer side was peeled off. Then, while applying a temperature of 50 to 60°C, the third adhesive layer formed from Composition S2-1 was laminated on the exposed first adhesive layer to obtain the adhesive film of Example 1. In addition, in order to easily peel off the PET film peeled off in these series of processes and the PET film peeled off at the time of circuit connection, each PET film was selected such that the peel strength between the second adhesive layer and the PET film was greater than the peel strength between the first adhesive layer and the PET film and the peel strength between the third adhesive layer and the PET film.

[0235] Regarding the adhesive films of Examples 2 to 4 and Comparative Examples 1 to 4, the adhesive films having the structures shown in Table 6 were produced in the same manner as in Example 1. Regarding Examples 5 and Comparative Example 5, the third adhesive layer was not laminated, and except for this, the adhesive films having the structures shown in Table 6 were produced in the same manner as in Example 1.

[0236] The thickness of the first adhesive layer of the produced adhesive film for circuit connection was measured by the following method. First, the adhesive film for circuit connection was sandwiched between two glasses (thickness: about 1 mm), and casting was performed using a resin composition composed of 100 g of bisphenol A type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of diethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.). Then, cross-section grinding was performed using a grinding machine, and the thickness of the first adhesive layer at the separated portion between adjacent conductive particles was measured using a scanning electron microscope (SEM, trade name: SE-8010, manufactured by Hitachi High-Tech Science Corporation). The thickness of the first adhesive layer was 1.8 μm.

[0237] Regarding the adhesive films obtained in Examples 1 to 5 and Comparative Examples 1 to 5, the results of measuring the projected particle density were all approximately 18,000 particles / mm 2 .

[0238] [Evaluation of Circuit Connection Structure]

[0239] <Fabrication of Circuit Connection Structure - 1>

[0240] As the first circuit component, an IC chip (0.9 mm × 20.3 mm, thickness: 0.3 mm, bump electrode size: 70 μm × 12 μm, space between bump electrodes: 12 μm, bump electrode thickness: 9 μm) with bump electrodes arranged in a staggered pattern in two columns was prepared. And, as the second circuit component, a component having a wiring pattern of Ti: 50 nm / Al: 400 nm (pattern width: 19 μm, space between electrodes: 5 μm) formed on the surface of a polyimide substrate (manufactured by DU PONT - TORAY CO., LTD., 200H) (38 mm × 28 mm, thickness: 0.05 mm) was prepared.

[0241] Circuit connection structures were fabricated using the adhesive films of Examples 1 to 5 and Comparative Examples 1 to 5. The adhesive film was cut into a width of 2.0 mm, and the adhesive film was placed on the first circuit component so that the third adhesive layer (the second adhesive layer in the case of Example 5 and Comparative Example 5) was in contact with the first circuit component. Using a thermocompression bonding device composed of a stage including a ceramic heater and a tool (8 mm × 50 mm), heating and pressing were performed at 70°C and 0.98 MPa (10 kgf / cm 2 ) for 2 seconds, the adhesive film was bonded to the first circuit component, and the release film on the side opposite to the first circuit component of the adhesive film was peeled off. Then, after aligning the bump electrodes of the first circuit component with the wiring pattern of the second circuit component, a heating tool was used with a size of 8 mm × 45 mm. As a buffer material, via a 50 - μm - thick Teflon (registered trademark), heating and pressing were performed at the actually measured maximum temperature of 170°C of the adhesive film and an area - converted pressure of 30 MPa on the bump electrodes for 5 seconds, and the first adhesive layer of the adhesive film was bonded to the second circuit component, thereby fabricating circuit connection structure - 1 respectively.

[0242] <Fabrication of Circuit Connection Structure - 2>

[0243] As the first circuit component, an IC chip (0.9 mm × 20.3 mm, thickness: 0.3 mm, bump electrode size: 70 μm × 12 μm, space between bump electrodes: 12 μm, bump electrode thickness: 5 μm) with bump electrodes arranged in two staggered columns was prepared. And, as the second circuit component, a component with a 150-nm-thick Al / Nd film formed on the surface of a glass substrate (25 mm × 35 mm, thickness: 0.2 mm) was prepared.

[0244] The above-described first circuit component and second circuit component were used. In addition, in the same manner as in the production of the circuit connection structure-1, circuit connection structures-2 were respectively produced using the adhesive films of Examples 1 to 5 and Comparative Examples 1 to 5.

[0245] (Evaluation of connection resistance)

[0246] Regarding the produced circuit connection structure-1, the initial connection resistance (on-resistance) was measured by the four-terminal method. During the measurement, a multimeter MLR21 manufactured by Kusumoto Chemicals, Ltd. was used. The potential difference was measured at any 14 points, and the average value was obtained. The average value of the potential difference was converted into a connection resistance value and evaluated according to the following criteria. The results are shown in Table 6.

[0247] A: The connection resistance value is less than 0.6 Ω

[0248] B: The connection resistance value is 0.6 Ω or more and less than 1.0 Ω

[0249] C: The connection resistance value is 1.0 Ω or more

[0250] (Evaluation of large indentations)

[0251] By observing the produced circuit connection structure-2 from the glass substrate side using a differential interference microscope, the presence or absence of indentations (large indentations) significantly stronger than those of the conductive particles (visually obvious) was confirmed. The case where such large indentations were not observed was evaluated as "A", and the case where such large indentations were observed was evaluated as "B".

[0252] [Table 6]

[0253]

[0254] <Production of the first adhesive layer - B>

[0255] After obtaining a composition by mixing the materials shown in Table 7 at the composition ratio (mass ratio) shown in Table 7 (the values in Table 7 refer to the amount of non-volatile components), it was coated on a demolded PET (polyethylene terephthalate) film, and organic solvents, etc. were hot air dried at 70°C for 5 minutes, whereby a composition layer formed from a composition containing each component was obtained respectively. The composition layer was coated so that the thickness after drying became 5 μm, thereby producing the first adhesive layer - B. Here, the thickness was measured using a contact thickness gauge.

[0256] [Table 7]

[0257]

[0258] <Production of the second adhesive layer - B>

[0259] After obtaining a composition by mixing the materials shown in Table 8 at the composition ratio (mass ratio) shown in Table 8 (the values in Table 8 refer to the amount of non-volatile components), it was coated on a demolded PET (polyethylene terephthalate) film, and organic solvents, etc. were hot air dried at 70°C for 5 minutes, whereby the second adhesive layer - B formed from a composition containing each component was produced respectively. The adhesive layer was coated so that the thickness after drying became 11 μm respectively. Here, the thickness was measured using a contact thickness gauge.

[0260] (Coating yield)

[0261] Regarding the coating yield when forming the second adhesive layer - B, the ratio Y (%) without white lines and scratches was determined, and evaluation was carried out according to the following criteria.

[0262] A+: Y is 95% or more

[0263] A: Y is 90% or more and less than 95%

[0264] B: Y is 80% or more and less than 90%

[0265] C: Y is less than 80%

[0266] [Table 8]

[0267]

[0268] (Example 6 and Comparative Examples 6 - 8)

[0269] [Production of adhesive film]

[0270] The adhesive films having the structures shown in Table 9 were produced using the above-prepared first adhesive layer-B and second adhesive layer-B. For example, in the adhesive film of Example 6, the first adhesive layer-B formed from Composition P-2 was laminated on the second adhesive layer-B formed from Composition S1-9 while applying a temperature of 50 to 60°C, thereby obtaining the adhesive film of Example 6.

[0271] Regarding the adhesive films of Comparative Examples 6 to 8, the adhesive films having the structures shown in Table 9 were produced in the same manner as in Example 6.

[0272] <Fabrication of Circuit Connection Structure-3>

[0273] As the first circuit component, an IC chip (0.9 mm × 20.3 mm, thickness: 0.3 mm, size of bump electrodes: 70 μm × 12 μm, space between bump electrodes: 12 μm, bump electrode thickness: 5 μm) in which bump electrodes were arranged in two rows in a staggered pattern was prepared. And, as the second circuit component, a component in which a Ti / Al / Ti film with a thickness of 150 nm was formed on the surface of a glass substrate (25 mm × 35 mm, thickness: 0.2 mm) was prepared.

[0274] The circuit connection structures were fabricated using the adhesive films of Example 6 and Comparative Examples 6 to 8. The adhesive film was cut into a width of 2.0 mm, and the adhesive film was disposed on the first circuit component so that the second adhesive layer-B was in contact with the first circuit component. Using a thermocompression bonding apparatus composed of a stage including a ceramic heater and a tool (8 mm × 50 mm), heating and pressing were performed at 70°C and 0.98 MPa (10 kgf / cm 2 ) for 2 seconds to laminate the adhesive film on the first circuit component, and the release film on the side opposite to the first circuit component of the adhesive film was peeled off. Then, after aligning the bump electrodes of the first circuit component with the wiring pattern of the second circuit component, using a heating tool with a size of 8 mm × 45 mm, as a buffer material via a Teflon (registered trademark) with a thickness of 50 μm, heating and pressing were performed at a maximum measured temperature of 145°C of the adhesive film and an area-converted pressure of 30 MPa on the bump electrodes for 5 seconds to laminate the first adhesive layer of the adhesive film on the second circuit component, thereby fabricating the circuit connection structure-3, respectively.

[0275] (Evaluation of Connection Resistance)

[0276] Regarding the fabricated circuit connection structure-3, the initial connection resistance (on-resistance) was measured by the four-terminal method. During the measurement, a multimeter MLR21 manufactured by Kusumoto Chemicals, Ltd. was used. The potential difference was measured at 14 arbitrary points, and the average value was obtained. The average value of the potential difference was converted into a connection resistance value and evaluated according to the following criteria. The results are shown in Table 9.

[0277] A: The connection resistance value is less than 5 Ω

[0278] B: The connection resistance value is 5 Ω or more and less than 10 Ω

[0279] C: The connection resistance value is 10 Ω or more

[0280] (Evaluation of large indentations)

[0281] By observing the fabricated circuit connection structure-3 from the glass substrate side using a differential interference microscope, the presence or absence of indentations (large indentations) that are significantly stronger than the indentations of the conductive particles (visually obvious) was confirmed. The case where such large indentations were not observed was evaluated as "A", and the case where such large indentations were observed was evaluated as "B".

[0282] [Table 9]

[0283]

[0284] Symbol Explanation

[0285] 1a, 1b - Adhesive film for circuit connection, 2 - First adhesive layer, 3 - Second adhesive layer, 4 - Conductive particles, 6 - Third adhesive layer, 10 - Circuit connection structure, 12 - Circuit electrode (first electrode), 13 - First circuit component, 15 - Bump electrode (second electrode), 16 - Second circuit component, 20, 22, 24 - Substrate.

Claims

1. An adhesive film for circuit connection, comprising: a first adhesive layer containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component; and a second adhesive layer provided on the first adhesive layer and containing a second thermosetting resin component. The second adhesive layer is formed of an inorganic filler-containing composition, and the inorganic filler-containing composition contains the second thermosetting resin component and an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% cumulative in the volume-based particle size distribution and a particle size D95 of 0.9 to 2.0 μm at 95% cumulative. The inorganic filler is a silica filler.

2. The adhesive film for circuit connection according to claim 1, further comprising a third adhesive layer, which is laminated on the side of the first adhesive layer opposite to the second adhesive layer and contains a third thermosetting resin component.

3. A method for manufacturing a circuit connection structure, comprising the steps of: interposing the adhesive film for circuit connection according to claim 1 or 2 between a first circuit component having a first electrode and a second circuit component having a second electrode, and thermocompression bonding the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other.

4. The method for manufacturing a circuit connection structure according to claim 3, wherein, one of the first circuit component and the second circuit component is an IC chip, and the other is a plastic substrate having an electrode containing Ti.

5. A circuit connection structure, comprising: a first circuit component having a first electrode; a second circuit component having a second electrode; and a circuit connection portion disposed between the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other, wherein the circuit connection portion contains a cured product of the adhesive film for circuit connection according to claim 1 or 2.

6. The circuit connection structure according to claim 5, wherein, one of the first circuit component and the second circuit component is an IC chip, and the other is a plastic substrate having an electrode containing Ti.

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