Adhesive composition and connection structure

Abstract

This adhesive composition contains conductive particles having a plurality of protrusions on the surface. The compressive hardness of the conductive particles at 20% compression is 350 kgf / mm2-1500 kgf / mm2. The ratio of the area of the protrusions to the area of the surface of the conductive particles is 30% or more.

Description

Adhesive composition and connection structure

[0001] The present invention relates to an adhesive composition and a connection structure.

[0002] In fields such as micro-OLEDs used in AR / VR applications, anisotropically conductive films are used to connect electronic components and microcircuit electrodes. Anisotropically conductive films are formed, for example, by dispersing conductive particles in an adhesive film. By sandwiching such an anisotropically conductive film between opposing electrodes and applying heat and pressure, the opposing electrodes can be electrically connected while maintaining the insulation between adjacent electrodes on the same substrate.

[0003] Various structures of electrodes connected by anisotropic conductive films are known. For example, Patent Document 1 describes a semiconductor device having protruding electrodes with a two-layer structure in which a first conductive layer and a second conductive layer formed on the first conductive layer are laminated, and the second conductive layer is made of a material with a lower hardness than the first conductive layer.

[0004] On the other hand, in anisotropic conductive films, conductive particles having protrusions on their surfaces are sometimes used. For example, Patent Document 1 discloses an adhesive composition containing an adhesive component and conductive particles, the conductive particles having plastic particles and a metal layer covering the plastic particles, and a plurality of protrusions formed on the surfaces of the conductive particles, the height of the plurality of protrusions being 85 to 1200 nm on average.

[0005] JP 2000-286299 A International Publication No. 2018 / 199329

[0006] According to the studies of the present inventors, when at least one electrode of two electronic components to be connected is composed of a relatively hard conductive layer (e.g., a Ni layer) and a relatively soft conductive layer (e.g., an Au layer) formed on the surface of the hard conductive layer (the outermost surface of the electrode), and when the soft conductive layer is thin, the connection resistance between the connected electronic components is more likely to increase when placed under high-temperature, high-humidity conditions (e.g., a temperature of 85°C and a humidity of 85%) for a long period of time, compared to when the soft conductive layer is thick. It is necessary for the adhesive composition to suppress the increase in resistance (to have excellent connection reliability) even when used to connect such electronic components.

[0007] Therefore, one aspect of the present invention aims to provide an adhesive composition that has a soft conductive layer on the outermost surface and that exhibits excellent connection reliability when used to connect electrodes in which the conductive layer is thin.

[0008] As a result of further research aimed at solving the above-mentioned problems, it was found that when the soft conductive layer on the outermost surface of the electrode is thick, the soft conductive layer deforms to conform to the shape of the conductive particles when heated and pressurized during mounting, resulting in a wide area of ​​contact between the electrode and the conductive particles and stable, good conductivity. On the other hand, when the soft conductive layer on the outermost surface of the electrode is thin, the conductive layer is less likely to deform, resulting in a small area of ​​contact between the electrode and the conductive particles, which is one of the reasons why connection resistance is likely to increase under high-temperature, high-humidity conditions.

[0009] Therefore, the inventors attempted to reduce the compression hardness of the conductive particles to flatten them when pressure is applied and increase the contact area between the electrode and the conductive particles. However, it became clear that if the compression hardness of the conductive particles is too low, the protrusions of the conductive particles may not sufficiently penetrate into the electrode, and good conductivity may not be obtained.

[0010] The inventors conducted further intensive research and discovered that by setting the compression hardness of the conductive particles and the ratio of the area of ​​the protrusions of the conductive particles within a specific range, it is possible to ensure a sufficient contact area between the electrode and the conductive particles while allowing the protrusions of the conductive particles to sufficiently penetrate into the electrode surface, thereby improving connection reliability under high-temperature, high-humidity conditions, and thus completed the present invention.

[0011] In some aspects, the present invention provides the following [1] to [7]. [1] A conductive material containing conductive particles having a plurality of protrusions on the surface thereof, the conductive particles having a compression hardness of 350 kgf / mm when compressed by 20%. ２ ~1500kgf / mm ２ an adhesive composition in which the ratio of the area of ​​the plurality of protrusions to the area of ​​the surface of the conductive particles is 30% or more. [2] A connection structure comprising: a first electronic component having a first electrode; a second electronic component having a second electrode; and a connection portion disposed between the first electronic component and the second electronic component and electrically connecting the first electrode and the second electrode, wherein the connection portion comprises a cured product of the adhesive composition described in [1]. [3] The connection structure described in [2], in which at least one of the first electrode and the second electrode comprises a surface layer containing Au. [4] The connection structure described in [3], in which the surface layer has a thickness of 3 μm or less. [5] A method for producing a connection structure, comprising the steps of: disposing the adhesive composition described in [1] between a first electronic component having a first electrode and a second electronic component having a second electrode; and thermocompression-bonding the first electronic component and the second electronic component via the adhesive composition to electrically connect the first electrode and the second electrode. [6] A method for producing a connection structure described in [5], in which at least one of the first electrode and the second electrode comprises a surface layer containing Au. [7] The method for manufacturing a connection structure according to [6], wherein the thickness of the surface layer is 3 μm or less.

[0012] According to one aspect of the present invention, an adhesive composition can be provided that has a soft conductive layer on the outermost surface and exhibits excellent connection reliability when used to connect electrodes in which the conductive layer is thin.

[0013] Fig. 1 is a schematic cross-sectional view showing one embodiment of an adhesive film; Fig. 2 is a schematic cross-sectional view showing one embodiment of a conductive particle; Fig. 3 is a schematic cross-sectional view showing another embodiment of an adhesive film; Fig. 4 is a schematic cross-sectional view showing one embodiment of a connection structure; Fig. 5 is a schematic cross-sectional view showing one embodiment of a method for manufacturing a connection structure.

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[0015] <Adhesive Composition> The adhesive composition according to one embodiment contains conductive particles having a plurality of protrusions on the surface thereof, and the conductive particles have a compression hardness of 350 kgf / mm when compressed by 20%. ２ ~1500kgf / mm ２ and the ratio of the area of ​​the protrusions to the area of ​​the surface of the conductive particles is 30% or more.

[0016] The adhesive composition typically further contains an adhesive component, and conductive particles are dispersed in the adhesive component. The adhesive composition may be in the form of a paste or a film. FIG. 1 is a schematic cross-sectional view showing one embodiment of a film-like adhesive composition (adhesive film). As shown in FIG. 1, in one embodiment, the adhesive film 1 is composed of a single layer made of an adhesive component (insulating adhesive) 2 and conductive particles 3 dispersed in the adhesive component 2.

[0017] 2A and 2B are cross-sectional views schematically illustrating an embodiment of a conductive particle 3. As shown in Fig. 2A, in one embodiment, a conductive particle 30A has a non-conductive core 31 and a conductive layer 32A that coats the core 31.

[0018] It is preferable that substantially the entire surface of core 31 is covered with conductive layer 32A, but a portion of the surface of core 31 may be exposed and not covered with conductive layer 32A, as long as the function of electrically connecting electronic components to each other is maintained.

[0019] The core 31 is formed of a non-conductive material such as glass, ceramic, or resin, and is preferably formed of resin. Examples of resins include acrylic resin, styrene resin, silicone resin, polybutadiene resin, and copolymers of the monomers that make up these resins. The core 31 may be a particle containing a polymer containing at least one monomer selected from styrene and divinylbenzene as a monomer unit. The polymer may further contain (meth)acrylate as a monomer unit. The diameter of the core 31 may be, on average, for example, 1 μm or more, or 2 μm or more, or 40 μm or less, 30 μm or less, or 20 μm or less.

[0020] The conductive layer 32A is composed of, for example, a single conductive layer. The conductive layer 32A is formed of, for example, Ni, Cu, Ag, Ru, or Pd, or an alloy containing these metal elements. The alloy may be, for example, an alloy containing Ni (Ni alloy). Examples of Ni alloys include Ni-B, Ni-P, and Ni-W-B. From the viewpoint of further suppressing a decrease in connection reliability when the soft outermost conductive layer is used to connect electrodes with a thin thickness, the conductive layer 32A is preferably formed of Pd. The thickness of the conductive layer 32A may be, for example, 50 nm or more and 300 nm or less. The thickness of the conductive layer 32A refers to the thickness of the conductive layer in the portion where the protrusions described below are not formed. The thickness of the conductive layer 32A can be measured using an electron microscope.

[0021] 2(b), in a conductive particle 30B according to another embodiment, the conductive layer 32B may be a two-layer conductive layer consisting of a first conductive layer 32a and a second conductive layer 32b. That is, the conductive particle 30B according to another embodiment includes a core 31, a first conductive layer 32a that covers the core 31, and a second conductive layer 32b that covers the first conductive layer 32a.

[0022] The first conductive layer 32a may be made of, for example, Ni. The second conductive layer 32b may be made of, for example, Au or Pd. That is, the conductive particle 30B may have a layer made of Au or Pd on the outermost surface side of the conductive particle 30B as a conductive layer.

[0023] The thickness of the first conductive layer 32a may be, for example, 50 nm or more and 300 nm or less. The thickness of the second conductive layer 32b may be, for example, 2 nm or more, 5 nm or more, or 10 nm or more, and may be 200 nm or less, 100 nm or less, or 50 nm or less. The thicknesses of the first conductive layer 32a and the second conductive layer 32b each refer to the thickness of the conductive layer portion where no protrusions, described below, are formed. The thicknesses of the first conductive layer 32a and the second conductive layer 32b can be measured using an electron microscope.

[0024] A plurality of protrusions 33 are formed on the surface of the conductive particle 3. In the conductive particle 30A shown in Fig. 2(a), the protrusions 33A are composed of a single conductive layer 32A. In the conductive particle 30B shown in Fig. 2(b), the protrusions 33B are composed of a two-layer conductive layer 32B, which is a first conductive layer 32a and a second conductive layer 32b.

[0025] The ratio of the area of ​​the multiple protrusions 33 to the surface area of ​​the conductive particle 3 (hereinafter also referred to as the "protrusion area ratio") is 30% or more. From the viewpoint of expanding the contact area between the conductive particle and the electrode and further improving connection reliability, the protrusion area ratio may be 32% or more, 35% or more, 38% or more, or 40% or more. Furthermore, the protrusion area ratio may be 70% or less, 65% or less, 60% or less, or 55% or less.

[0026] The area ratio of the protrusions is determined by analyzing a black-and-white SEM image of the conductive particles 3 generated by imaging using a scanning electron microscope (SEM). Analysis of the SEM image can be performed using the method described in JP 2016-61722 A. Specifically, the area ratio of the protrusions can be determined by a method including the steps of: detecting a particle edge, which is the boundary between the projected image of each conductive particle 3 and other regions in an SEM image of a plurality of conductive particles 3; calculating a second threshold value corresponding to the boundary between the protrusions and other regions from the frequency distribution of brightness in the region inside the particle edge; binarizing the region inside the particle edge using the obtained second threshold value to generate a binary image; calculating the ratio of the area of ​​the region corresponding to the protrusions to the area of ​​the region inside the particle edge in the obtained binary image as the area ratio of the protrusions of each conductive particle 3; and calculating the average value of the area ratios of the protrusions calculated for 100 conductive particles 3.

[0027] In the analysis of the above SEM image, the particle edge substantially corresponds to the outer periphery of the two-dimensional projection image of the conductive particle 3, including the unevenness resulting from the protrusions. The frequency distribution of brightness obtained from the SEM image generally shows a minimum value reflecting the particle edge portion. The SEM image is binarized using the brightness corresponding to this minimum value as a first threshold to generate a binarized image. The edge formed in the obtained binarized image is detected as the particle edge. The central coordinates of the conductive particle 3 on the SEM image are calculated based on the particle edge. A circle fitting to the particle edge is found using the least squares method, and the center of that circle is defined as the central coordinate of the conductive particle 3, with the radius of that circle being determined as r. Then, a circular region of radius r / 2 centered on the central coordinate is identified as the region inside the particle edge.

[0028] In the luminance frequency distribution in the region inside the particle edge, the low-luminance side generally reflects the luminance values ​​of pixels included in the region combining the particle surface and the portion excluding the protrusion edge, while the high-luminance side mainly reflects the luminance values ​​of pixels included in the region of the protrusion edge. The low-luminance side has a peak in the frequency representing the portion excluding the particle surface and the protrusion edge, while the high-luminance side has a portion with the greatest rate of decrease in the frequency, indicating that the portion excluding the particle surface and the protrusion edge rapidly decreases as the luminance increases. Based on this frequency distribution, the second threshold is selected between the luminance value corresponding to the maximum value of the frequency on the low-luminance side and the luminance value corresponding to the portion with the greatest rate of decrease on the high-luminance side. More specifically, the second threshold is set to a luminance value intermediate between the luminance value corresponding to the maximum value of the frequency on the low-luminance side and the luminance value corresponding to the point with the greatest rate of decrease on the high-luminance side. Based on this second threshold, a binary image of the area inside the particle edge is generated, and the ratio of the area of ​​the white area in the binary image to the area of ​​the area inside the particle edge is calculated as the area ratio of the protrusion of each conductive particle 3.

[0029] The average height of the multiple protrusions 33 may be 50 nm or more, 70 nm or more, 90 nm or more, 110 nm or more, or 130 nm or more, and may be 1200 nm or less, 1000 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 150 nm or less.

[0030] The average height of the plurality of protrusions 33 can also be determined by analyzing an SEM image of the conductive particles according to the method described in JP 2016-61722 A. Specifically, for example, the average height can be determined by a method including the steps of: detecting particle edges, which are boundaries between the projected images of each conductive particle 3 and other regions in an SEM image in which a plurality of conductive particles 3 are captured; calculating the central coordinates of the conductive particles 3 on the SEM image based on the particle edges; dividing the particle edges into 18 particle edge portions, each of which is formed by shifting a region of 40 degrees in polar coordinates centered on the central coordinates by 20 degrees; calculating the difference between the maximum and minimum values ​​of the distance between the central coordinates and the particle edge for each particle edge portion; and calculating the average value of these differences as the average height of the protrusions 33; and calculating the average height of the protrusions 33 for 100 conductive particles 3 and calculating the average value.

[0031] In the analysis of the SEM images, the maximum distance between the center coordinate and the particle edge for each particle edge portion is determined by selecting the three points constituting the edge of each particle edge portion with the greatest distance from the center coordinate and calculating the average value thereof. The minimum distance between the center coordinate and the particle edge for each particle edge portion is determined by selecting the three points constituting the edge of each particle edge portion with the smallest distance from the center coordinate and calculating the average value thereof.

[0032] The average particle size of the conductive particles 3 may be 1.0 μm or more, 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, or 3.2 μm or more, and may be 10 μm or less, 8.0 μm or less, 6.0 μm or less, 5.0 μm or less, or 4.0 μm or less. In this specification, the particle size of any 300 conductive particles 3 is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle sizes is defined as the average particle size. More specifically, the average particle size of the conductive particles 3 is determined by using the least squares method to find a circle fitting to the particle edge of each conductive particle 3 in an SEM image of the conductive particles 3, as described above, and then calculating the average particle size of the 300 conductive particles 3, taking the diameter of the circle as the particle size of each conductive particle 3.

[0033] The compression hardness of the conductive particles 3 when compressed by 20% is 350 kgf / mm ２ ~1500kgf / mm ２ The compression hardness of the conductive particles 3 when compressed by 20% is 380 kgf / mm ２ Over 400 kgf / mm ２ Over 420 kgf / mm ２ or more, or 450 kgf / mm ２ or more, 1300 kgf / mm ２ Below, 1200kgf / mm ２ Below, 1100kgf / mm ２ Below, 1000kgf / mm ２ Below, 900kgf / mm ２ or less, or 800 kgf / mm ２ or less. A larger compression hardness of the conductive particles 3 is preferable because, when the adhesive composition is used as an anisotropically conductive adhesive composition, the protrusions of the conductive particles can be more easily embedded into the electrode surface. On the other hand, a smaller compression hardness of the conductive particles is preferable because, when the adhesive composition is used as an anisotropically conductive film, the conductive particles can be more easily flattened, and the contact area between the electrode and the conductive particles can be more easily increased.

[0034] The compression hardness (hereinafter sometimes referred to as "K value") of the conductive particles 3 is measured using a surface hardness compression measuring device (for example, HM2000 manufactured by Fischer Instruments Inc.). Specifically, first, the conductive particles 3 are scattered on a slide glass (S1214 manufactured by Matsunami Glass Industrial Co., Ltd.) on a stage set at 25°C. One conductive particle 3 is then selected from the scattered conductive particles 3, and compressed from the center at a rate of 0.33 mN / sec with an initial load of 0.1 mN using a prismatic diamond indenter having a square base with sides of 50 μm. The K value can be determined from the stress-strain curve. Specifically, the compression hardness of an elastic sphere is expressed as F=(2 １／２ / 3) x (S ３／２ ) × (E × R １／２ ) / (1-σ ２ ) and the following formula: K = E / (1 - σ ２ ) = (3 / 2１／２ ) x F x (S －３／２ ) × (R －１／２ ) can be calculated using the following formula: K = 3000F / (D ２ ×X ３／２ ) x 10 ６ The K value at any deformation rate can be determined by the following formula: X = (S / D) × 100. The compression hardness of the conductive particles 3 when compressed by 20% means the K value when the deformation rate X is 20%. The maximum test load in the compression test is set to, for example, 50 mN.

[0035] The recovery rate of the conductive particles 3 may be 10% or more, 20% or more, 25% or more, or 30% or more, and may be 100% or less, 90% or less, 80% or less, 75% or less, or 70% or less.

[0036] The recovery rate of the conductive particles 3 is measured using a surface hardness compression measuring device (e.g., HM2000 manufactured by Fischer Instruments Inc.). Specifically, the conductive particles 3 are first scattered on a slide glass (S1214 manufactured by Matsunami Glass Industrial Co., Ltd.) on a stage set to 25°C. One conductive particle 3 is then selected from the scattered conductive particles 3, and compressed using a prismatic diamond indenter having a square base with sides of 50 μm at an initial load of 0.1 mN from the center at a rate of 0.33 mN / sec until a load of 5 mN is applied, and then the load is reversed at a rate of 0.33 mN / sec to the initial load value. Here, when the displacement of the conductive particle 3 from the initial load (load 0.1 mN) to the load reversal (load 5 mN) is defined as L2, and the displacement of the conductive particle 3 from the load reversal to the final load (load 0.1 mN) is defined as L1 / L2 × 100 (%), the recovery rate of the conductive particle 3 is calculated. This operation is performed for 10 conductive particles 3 and the average value is calculated to calculate the recovery rate of the conductive particle 3 in this embodiment.

[0037] The conductive particles 3 having the protrusions described above can be obtained, for example, by forming conductive layers 32A, 32B by metal plating on the surface of the core 31. During the metal plating, the protrusions 33 can be formed by changing the plating conditions to vary the thickness of the conductive layers 32A, 32B. For example, the protrusions 33 can be formed by gradually increasing the concentration of the plating solution during the metal plating process.

[0038] Alternatively, a conductive layer having bump-like protrusions can be formed by adjusting the pH of the plating solution, for example, by adjusting the pH of a nickel plating solution to 6 (see Mochizuki et al., Surface Technology, Vol. 48, No. 4, pp. 429-432, 1997). When glycine is used as a complexing agent that contributes to the stability of the plating bath, a conductive layer having a flat surface is formed, whereas when tartaric acid or DL-malic acid is used as a complexing agent, bump-like protrusions are formed (see, for example, Ogihara et al., Amorphous Plating, Vol. 36, pp. 35-37, 1994; Ogihara et al., Journal of the Japan Society of Circuit Packaging, Vol. 10, No. 3, pp. 148-152, 1995). By employing these methods, conductive layers 32A and 32B having protrusions 33 can be formed.

[0039] When producing the conductive particle 30B shown in Figure 2(b), for example, a first conductive layer 32a having protrusions can be formed by the above-mentioned method, and then a layer of Au or Pd can be formed by displacement plating to obtain a second conductive layer 32b.

[0040] The area ratio of the protrusions in the conductive particles 3 can be adjusted, for example, by adjusting the concentration when gradually increasing the concentration of the plating solution during the metal plating process. For example, by suddenly increasing the concentration of the plating solution, the reaction can be accelerated and the area ratio of the protrusions can be increased. Furthermore, the compression hardness of the conductive particles can be adjusted, for example, when the core is formed of a resin, by appropriately adjusting the type of resin (or the copolymerization ratio of monomers when the resin is a copolymer).

[0041] Furthermore, the conductive particles 3 having the protrusions described above can also be obtained, for example, by disposing an insulating or conductive core material on the surface of the core 31 and then forming the conductive layers 32A, 32B by metal plating. In this case, the area ratio of the protrusions in the conductive particles 3 can be adjusted, for example, by changing the amount of core material disposed on the surface of the core 31.

[0042] The content of the conductive particles 3 may be 5% by mass or more, 10% by mass or more, and 30% by mass or less, or 25% by mass or less, based on the total mass of the solid content in the adhesive composition.

[0043] The content of the conductive particles 3 may be 1% by volume or more, 50% by volume or less, or 40% by volume or less, based on the total volume of the solid content in the adhesive composition.

[0044] The adhesive component 2 is made of, for example, an insulating material that is curable by heat or light. The adhesive component 2 may contain a polymerizable substance having a functional group that undergoes radical polymerization. An example of the polymerizable substance is (meth)acrylate.

[0045] Examples of (meth)acrylates include (poly)urethane (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dimethyloltricyclodecane diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxypolyethoxy)phenyl]propane, dicyclopentenyl acrylate, tricyclodecanyl acrylate, bis(acryloxyethyl)isocyanurate, ε-caprolactone-modified tris(acryloxyethyl)isocyanurate, tris(acryloxyethyl)isocyanurate, and ethylene oxide-modified phosphate di(meth)acrylate. When ethylene oxide-modified di(meth)acrylate phosphate is used as the (meth)acrylate, the adhesive strength of the adhesive composition can be further improved.

[0046] The adhesive component 2 may contain only (meth)acrylate as the polymerizable substance, or may contain other polymerizable substances other than (meth)acrylate. The polymerizable substance is a substance having a functional group that polymerizes by radicals. Examples of other polymerizable substances include maleimide compounds.

[0047] The content of the polymerizable substance may be 10% by mass or more, 20% by mass or more, 30% by mass or more, or 40% by mass or more, based on the total mass of the adhesive component 2, and may be 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0048] The adhesive component 2 may contain a curing agent (thermal radical polymerization initiator). The curing agent is a compound that decomposes when heated to generate free radicals.

[0049] Examples of the curing agent include peroxides and azo compounds. Examples of the peroxides include diacyl peroxides such as dioctanoyl peroxide, dilauroyl peroxide, distearoyl peroxide, and dibenzoyl peroxide; peroxydicarbonates such as bis(4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate; t-butyl peroxypivalate, t-hexyl peroxypivalate, and the like. peroxymethyl butyl ether, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t peroxy esters such as 1,1-bis(t-butylperoxylaurate, t-butylperoxy-2-ethylhexyl monocarbonate, t-butyl peroxybenzoate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, and t-butyl peroxyacetate; peroxy ketals such as 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-2-methylcyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, and 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane; dialkyl peroxides such as dicumyl peroxide, t-butylcumyl peroxide, and di-t-butyl peroxide; and hydroperoxides such as p-menthane hydroperoxide.

[0050] Examples of azo compounds include 2,2'-azobis(2,4-dimethylvaleronitrile) and 2,2'-azobisisobutyronitrile.

[0051] As the curing agent, one of the above peroxides and azo compounds may be used alone, or two or more may be used in combination. The adhesive component preferably contains at least one of a diacyl peroxide and a peroxyester as the curing agent. The one-minute half-life temperature of the diacyl peroxide and the peroxyester may each independently be 90 to 175°C. Furthermore, the molecular weight of the diacyl peroxide and the peroxyester may each independently be 180 to 1,000.

[0052] The content of the curing agent may be 0.05% by mass or more, 0.1% by mass or more, 1% by mass or more, or 2% by mass or more, based on the total mass of adhesive component 2, and may be 20% by mass or less, 10% by mass or less, or 8% by mass or less.

[0053] The adhesive component 2 may contain a thermoplastic resin. Examples of the thermoplastic resin include polyamide resin, phenoxy resin, (meth)acrylic resin, polyimide resin, polyester resin, polyurethane resin, polyester urethane resin, and polyvinyl butyral resin. These thermoplastic resins may be used alone or in combination of two or more.

[0054] The content of the thermoplastic resin may be 20% by mass or more and 50% by mass or less based on the total mass of the adhesive component 2 .

[0055] The adhesive component 2 may further contain other components such as a cure adjuster, an adhesion promoter, a coupling agent (such as a silane coupling agent), an ion trapping agent, a visualization agent, a dispersant, a photoradical polymerization initiator, a filler, etc. The content of the other components may be, for example, 1% by mass or more and 20% by mass or less based on the total mass of the adhesive component.

[0056] In other embodiments, the adhesive film may have two or more regions. The adhesive film may include a first region including a first adhesive component and a second region adjacent to the first region including a second adhesive component. Each of the first region and the second region may be a layer.

[0057] For example, as shown in FIG. 3 , the adhesive film 1 may have a two-layer structure including a layer 1A containing conductive particles 3A (a first adhesive layer consisting of adhesive component 2A and conductive particles 3A dispersed in adhesive component 2A) and a layer 1B not containing conductive particles (a second adhesive layer consisting of adhesive component 2B). In this case, the first adhesive layer 1A may contain the above-mentioned polymerizable substance, curing agent, cure adjuster, thermoplastic resin, conductive particles, and other components as needed. The second adhesive layer 1B may contain the above-mentioned polymerizable substance, curing agent, cure adjuster, thermoplastic resin, and other components as needed. The types of components contained in the second adhesive layer 1B may be the same as or different from those in the first adhesive layer 1A.

[0058] The contents of the polymerizable substance, curing agent, cure adjuster, thermoplastic resin, and other components in the first adhesive layer and the second adhesive layer may each independently be the same as the contents of each component in the adhesive composition described above. In this case, "based on the total mass of the adhesive components" should be read as "based on the total mass of the adhesive components contained in the first adhesive layer" or "based on the total mass of the adhesive components contained in the second adhesive layer."

[0059] The number density of the conductive particles 3 in the adhesive film 1 is 1000 particles / mm 2 More than 3000 pieces / mm 2 More than 5000 pieces / mm 2 More than 7000 pieces / mm 2 or more than 8000 pieces / mm 2 or more, and 15,000 pieces / mm 2 Below, 13000 pieces / mm 2 Below, 12000 pieces / mm 2 or less than 11,000 pieces / mm 2 The number density of the conductive particles 3 can be determined by counting the number of conductive particles 3 per unit area of ​​the adhesive film 1 using an electron microscope.

[0060] The thickness of the adhesive film 1 may be, for example, 5 μm or more, or 10 μm or more, and may be 50 μm or less, 30 μm or less, or 20 μm or less.

[0061] The adhesive composition (adhesive film 1) may be a conductive adhesive composition (conductive adhesive film) or an anisotropically conductive adhesive composition (anisotropically conductive adhesive film). The adhesive composition can be suitably used for producing a connection structure.

[0062] <Connection structure> A connection structure according to one embodiment includes a first electronic component having a first electrode, a second electronic component having a second electrode, and a connection portion disposed between the first electronic component and the second electronic component and electrically connecting the first electrode and the second electrode to each other, wherein the connection portion includes a cured product of the adhesive composition described above.

[0063] 4 is a schematic cross-sectional view showing one embodiment of a connection structure 10. As shown in FIG. 4, the connection structure 10 includes a first electronic member 4 and a second electronic member 5 facing each other, and a connection portion 6 connecting the first electronic member 4 and the second electronic member 5 between the first electronic member 4 and the second electronic member 5.

[0064] The first electronic component 4 includes a first substrate 41 and a first electrode 42 formed on a main surface 41 a of the first substrate 41. The second electronic component 5 includes a second substrate 51 and a second electrode 52 formed on a main surface 51 a of the second substrate 51.

[0065] There are no particular limitations on the first electronic member 4 and the second electronic member 5 as long as they are members having electrodes that require electrical connection. Examples of members having electrodes include active elements such as diodes such as micro OLEDs, semiconductor chips, transistors, and thyristors, passive elements such as capacitors, resistors, and coils, and substrates having electrodes such as printed circuit boards.

[0066] The first substrate 41 and the second substrate 51 may be a silicon substrate, a glass substrate, a flexible substrate, etc. The flexible substrate may contain at least one thermoplastic resin selected from the group consisting of polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene naphthalate (PEN), for example.

[0067] Examples of electrode materials for forming the first electrode 42 and the second electrode 52 include metals such as Ag, Ni, Al, Au, Cu, Ti, and Mo, metal oxides such as ITO and IZO, and conductors such as silver nanowires and carbon nanotubes. The first electrode 42 and the second electrode 52 may be made of the same material or different materials.

[0068] In one embodiment, the first electrode 42 may include a base layer provided on the first substrate 41 and a surface layer provided on the base layer. In another embodiment, the second electrode 52 may include a base layer provided on the second substrate 51 and a surface layer provided on the base layer. These surface layers are located on the outermost surfaces of the first electrode 42 and the second electrode 52, respectively. Either the first electrode 42 or the second electrode 52 may include a base layer and a surface layer, or both the first electrode 42 and the second electrode 52 may include a base layer and a surface layer.

[0069] The base layer may include a hard metal such as Ni, and the surface layer may include a soft metal such as Au, Pd, etc. The hardness of the surface layer may be less than that of the base layer.

[0070] The thickness of the surface layer may be 0.005 μm or more, or 0.01 μm or less, or 5 μm or less, or 3 μm or less. In an adhesive film according to one embodiment, the compression hardness of the conductive particles and the area ratio of the protrusions of the conductive particles are within specific ranges, so that even if the electrode has a base layer made of a hard metal and the surface layer is thin, the contact area between the electrode and the adhesive film is sufficiently large and the protrusions of the conductive particles can easily dig into the electrode.

[0071] The first electronic member 4 and the second electronic member 5 may each be provided with one first electrode 42 or one second electrode 52, but preferably a large number of electrodes are provided at predetermined intervals.

[0072] The connection portion 6 contains an insulating material 7, which is a cured product of an adhesive component, and conductive particles 3. The conductive particles 3 may be disposed not only between the opposing first electrode 42 and second electrode 52, but also between the main surface 41 a of the first substrate 41 and the main surface 51 a of the second substrate 51. In the connection structure 10, the first electrode 42 and the second electrode 52 are electrically connected via the conductive particles 3. That is, the conductive particles 3 are in contact with both the first electrode 42 and the second electrode 52.

[0073] In the connection structure 10, as described above, the opposing first electrode 42 and second electrode 52 are electrically connected via the conductive particles 3. This sufficiently reduces the connection resistance between the first electrode 42 and the second electrode 52. This allows the current to flow smoothly between the first electrode 42 and the second electrode 52, allowing the first electronic member 4 and the second electronic member 5 to fully exhibit their functions.

[0074] <Method for manufacturing connection structure> The connection structure can be manufactured by a method comprising the steps of: placing the adhesive composition between a first electronic component having a first electrode and a second electronic component having a second electrode; and thermocompression bonding the first electronic component and the second electronic component via the adhesive composition to electrically connect the first electrode and the second electrode to each other.

[0075] 5 is a schematic cross-sectional view showing one embodiment of a method for manufacturing a connection structure. As shown in FIG. 5( a), first, an adhesive film 1 (a film-like adhesive composition) is placed on the main surface 41 a of a first electronic component 4. When the adhesive film 1 is laminated on a substrate (not shown), the adhesive film 1 side of the substrate is placed on the first electronic component 4 so that it faces the first electronic component 4. When the adhesive film 1 has a first adhesive layer 1A and a second adhesive layer 1B as shown in FIG. 3, it is preferable to place the first adhesive layer 1A side in contact with the main surface 41 a of the first electronic component 4, from the viewpoint of increasing the number of conductive particles captured between the opposing electrodes.

[0076] After the adhesive film 1 is placed on the main surface 41 a of the first electronic member 4, the laminate of the adhesive film 1 and the first electronic member 4 may be pressed in the stacking direction to temporarily connect the adhesive film 1 to the first electronic member 4. At this time, heating may be performed together with the pressing.

[0077] 5(b), the second electronic component 5 is further placed on the adhesive film 1 placed on the first electronic component 4 so that the second electrode 52 faces the first electronic component 4 (i.e., the first electrode 42 and the second electrode 52 are placed opposite each other, and the adhesive film 1 is placed between the first electronic component 4 and the second electronic component 5). If the adhesive film 1 is laminated on a substrate (not shown), the substrate is peeled off and then the second electronic component 5 is placed on the adhesive film 1.

[0078] The first electronic member 4 and the second electronic member 5 are then thermocompression bonded together via the adhesive film 1. The thermocompression bonding is performed, for example, by applying heat and pressure in the direction of arrow A in FIG. 5(b). The application of heat and pressure in the direction of arrow A hardens the adhesive film 1, and the first electrode 42 and the second electrode 52 are electrically connected to each other. As a result, a connection structure 10 as shown in FIG. 4 is obtained.

[0079] The pressure applied during thermocompression bonding may be, for example, 5 MPa or higher and 20 MPa or lower. The heating during thermocompression bonding may be, for example, 100° C. or higher and 170° C. or lower, 150° C. or lower, or 130° C. or lower. The pressure application time and heating time during thermocompression bonding may be, for example, 10 seconds or longer and 60 seconds or shorter.

[0080] In the connection structure 10 obtained as described above, it is possible to bring the conductive particles 3 into contact with both the opposing first electrode 42 and second electrode 52, and the connection resistance between the first electrode 42 and the second electrode 52 can be sufficiently reduced.

[0081] By heating and pressurizing the adhesive film 1, the adhesive component 2 hardens and becomes an insulating material 7 while the distance between the first electrode 42 and the second electrode 52 is kept sufficiently small, and the first electronic component 4 and the second electronic component 5 are firmly connected via the connection portion 6.

[0082] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0083] <Preparation of Conductive Particles A1 to A8 and a1 to a4> Conductive particles A1 to A8 and a1 to a4 were prepared as follows. (Preparation of Conductive Particle A1) Tetramethylolmethane tetraacrylate, divinylbenzene, and styrene were used as monomers, and these were polymerized by suspension polymerization using a polymerization initiator (benzoyl peroxide) to obtain cores (average particle size: 5.0 μm). The cores were subjected to electroless Ni plating to obtain conductive particles having protrusions and a conductive layer formed of Ni (Ni layer, thickness: 60 nm). A layer formed of Pd having protrusions (Pd layer, thickness: 10 nm) was formed on the Ni layer of the conductive particles by displacement plating to obtain conductive particle A1.

[0084] (Preparation of Conductive Particles A2) Cores (average particle size: 3 μm) were subjected to electroless Ni plating to obtain conductive particles A2 having protrusions and a conductive layer formed of Ni (Ni layer, thickness: 120 nm).

[0085] (Preparation of Conductive Particles A3) Cores (average particle size: 3.25 μm) were subjected to electroless Ni plating to obtain conductive particles A3 having protrusions and a conductive layer formed of Ni (Ni layer, thickness: 140 nm).

[0086] (Preparation of Conductive Particles A4) Conductive particles A4 having protrusions and a conductive layer formed of Ni-WB were prepared by plating the surface of a core (average particle size: 3 μm) with Ni-WB.

[0087] (Preparation of conductive particles A5) Conductive particles A5 having protrusions and a conductive layer formed of Pd (Pd layer, thickness: 26 nm) were obtained by plating the surface of a core (average particle size: 3 μm) with Pd.

[0088] (Preparation of Conductive Particles A6) Cores (average particle size: 3 μm) were subjected to electroless Ni plating to obtain conductive particles A6 having protrusions and a conductive layer (Ni layer) formed of Ni.

[0089] (Preparation of conductive particles A7) Conductive particles A7 having protrusions and a conductive layer formed of Pd (Pd layer, thickness: 24.4 nm) were obtained by plating the surface of a core (average particle size: 3 μm) with Pd.

[0090] (Preparation of Conductive Particles A8) Conductive particles A8 having protrusions and a conductive layer formed of Ni (Ni layer, thickness: 140 nm) were obtained by electroless Ni plating of cores (average particle size: 5 μm).

[0091] (Preparation of conductive particles a1) Cores (average particle size: 3 μm) were subjected to electroless Ni plating to obtain conductive particles a1 having protrusions and a conductive layer formed of Ni (Ni layer, thickness: 110 nm).

[0092] (Preparation of conductive particles a2) Cores (average particle size: 3 μm) were subjected to electroless Ni plating to obtain conductive particles having protrusions and a conductive layer (Ni layer) formed of Ni. A layer (Pd layer) having protrusions formed of Pd (Pd layer) was formed on the Ni layer of the conductive particles by displacement plating to obtain conductive particles a2.

[0093] (Preparation of conductive particles a3) By applying Ni-P plating to the surface of a core (average particle size: 3 μm), conductive particles a3 having protrusions, a conductive layer formed of Ni-P, and an area ratio and average height of the protrusions as shown in Table 1 were obtained.

[0094] (Preparation of conductive particles a4) Cores (average particle size: 3.8 μm) were subjected to electroless Ni plating to obtain conductive particles a4 having protrusions and a conductive layer formed of Ni (Ni layer, thickness: 120 nm).

[0095] <Analysis of Conductive Particles A1 to A8 and a1 to a4> (Area Ratio of Protrusions) Conductive particles A1 to A8 and a1 to a4 were each collected on carbon tape, and the collected conductive particles were imaged using a scanning electron microscope (SEM) to obtain SEM images including each conductive particle. The SEM images were analyzed using the method described in the Detailed Description of the Invention section, and the area ratios of protrusions for conductive particles A1 to A8 and a1 to a4 were determined. The results are shown in Table 1.

[0096] (Compression Hardness at 20% Compression) The compression hardness of the conductive particles at 20% compression was determined by the following method. A microcompression tester (Fisher Instruments, HM2000) was prepared, and conductive particles were scattered on a slide glass (Matsunami Glass Industrial Co., Ltd., S1214) on a stage set to 25°C. One particle was selected from the scattered conductive particles, and compressed from the center at a rate of 0.33 mN / sec with an initial load of 0.1 mN using a prismatic diamond indenter having a square base with sides of 50 μm. A stress-strain curve was obtained. The load value when the particle diameter of the conductive particle was deformed by 20% (at 20% compression) was read, and the compression hardness of the conductive particle at 20% compression was calculated using the following formula. The results are shown in Table 1. Compression hardness of conductive particle at 20% compression = (3 / √2) × F ２０ ×S ２０ －３／２ ×R －１／２ x10 －３ R: Radius of conductive particle (μm), S ２０ : Displacement at 20% compression (mm), F ２０ : Load at 20% compression (N)

[0097] Example 1 Synthesis of Polyurethane Acrylate (UA1) 2,500 parts by mass (2.50 mol) of poly(1,6-hexanediol carbonate) (trade name: Duranol T5652, manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight 1,000) and 666 parts by mass (3.00 mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich Co.) were uniformly added dropwise over a period of 3 hours to a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser with a calcium chloride drying tube, and a nitrogen gas inlet tube. Subsequently, nitrogen gas was sufficiently introduced into the reaction vessel, and the reaction vessel was then heated to 70 to 75°C to allow the mixture to react. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (Sigma-Aldrich) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (Sigma-Aldrich) were added to the reaction vessel, followed by the addition of 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (Sigma-Aldrich), and the mixture was allowed to react for 6 hours at 70°C in an air atmosphere. This yielded polyurethane acrylate (UA1). The weight-average molecular weight of polyurethane acrylate (UA1) was 15,000. The weight-average molecular weight was measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene under the following conditions. (Measurement conditions) Apparatus: GPC-8020 manufactured by Tosoh Corporation Detector: RI-8020 manufactured by Tosoh Corporation Column: Gelpack GLA160S + GLA150S manufactured by Resonaq Techno Service Co., Ltd. Sample concentration: 120 mg / 3 mL Solvent: tetrahydrofuran Injection volume: 60 μL Pressure: 2.94 × 10 Pa (30 kgf / cm) Flow rate: 1.00 mL / min

[0098] (Method for Preparing Polyester Urethane Resin) 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were charged into a heated stainless steel autoclave equipped with a stirrer, thermometer, condenser, vacuum generator, and nitrogen gas inlet tube, and 0.02 parts by mass of tetrabutoxy titanate as a catalyst was further charged. The temperature was then raised to 220°C under a nitrogen stream and stirred for 8 hours. The pressure was then reduced to atmospheric pressure (760 mmHg) and cooled to room temperature. This resulted in the precipitation of a white precipitate. The white precipitate was then removed, washed with water, and vacuum-dried to obtain a polyester polyol. The resulting polyester polyol was thoroughly dried and then dissolved in MEK (methyl ethyl ketone) and charged into a four-neck flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a nitrogen gas inlet tube. Furthermore, dibutyltin dilaurate was charged as a catalyst in an amount of 0.05 parts by mass per 100 parts by mass of polyester polyol. Furthermore, 4,4'-diphenylmethane diisocyanate in an amount of 50 parts by mass per 100 parts by mass of polyester polyol was dissolved in MEK and added using a dropping funnel, followed by stirring at 80°C for 4 hours to obtain a polyester urethane resin.

[0099] (Preparation of First Adhesive Composition) As a polymerizable substance, 17 parts by mass of dimethyloltricyclodecane diacrylate (product name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 30 parts by mass of the polyurethane acrylate synthesized as described above, and 1.5 parts by mass of ethylene oxide-modified phosphate dimethacrylate (product name: PM-21, manufactured by Nippon Kayaku Co., Ltd.) were used, and 2 parts by mass of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (product name: Perhexa 25O, manufactured by NOF Corporation) were used as a curing agent. 0.5 parts by mass of the polyester urethane resin prepared as described above as a thermoplastic resin, 45 parts by mass of the polyester urethane resin prepared as described above, 2.8 parts by mass of 3-glycidoxypropyltrimethoxysilane (product name: SH-6040, manufactured by Dow Corning Toray Co., Ltd.) as a silane coupling agent, 2.5 parts by mass of Aerosil (product name: MR-202, manufactured by Nippon Aerosil Co., Ltd.) as a filler, and 26 parts by mass of the conductive particles A1 prepared by the above method were mixed to obtain a first adhesive composition. The content of the conductive particles, based on the total volume of the first adhesive composition, was 4% by volume. (Preparation of Second Adhesive Composition) As polymerizable substances, 30 parts by mass of dimethyloltricyclodecane diacrylate (product name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 27.5 parts by mass of the polyurethane acrylate synthesized as described above, and 2.5 parts by mass of ethylene oxide-modified phosphate dimethacrylate (product name: PM-21, manufactured by Nippon Kayaku Co., Ltd.) were used, and as a curing agent, 5.0 parts by mass of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (product name: Perhexa 25O, manufactured by NOF Corporation) was used. A second adhesive composition was obtained by mixing 27.5 parts by mass of the polyester urethane resin prepared as described above, 15 parts by mass of a phenoxy resin (product name: Phenototo ZX-1356-2, manufactured by Nippon Steel Chemical & Material Co., Ltd.) as the resin, 5 parts by mass of 3-glycidoxypropyltrimethoxysilane (product name: SH-6040, manufactured by Dow Corning Toray Co., Ltd.) as the silane coupling agent, and 8 parts by mass of Aerosil (product name: R-202, manufactured by Nippon Aerosil Co., Ltd.) as the filler.

[0100] The first adhesive composition was applied to a substrate (a 50 μm-thick PET film) using an applicator to prepare a first adhesive layer. A second adhesive layer was prepared using the second adhesive composition in the same manner as the first adhesive layer. The first adhesive layer and the second adhesive layer were then bonded together using a laminator to prepare an adhesive film (thickness: 14 μm).

[0101] (Measurement of number density) Using an electron microscope, the number of conductive particles contained in the prepared adhesive film was measured by 1 mm ２ The number density of conductive particles in the adhesive film was determined by counting the number per square inch. The results are shown in Table 1.

[0102] (Preparation of Electronic Components) The following electronic components were prepared. Glass Component: A glass component was prepared, including a glass substrate and Ti / Al / Ti wiring formed on the glass substrate. The thickness of this glass substrate was 0.7 mm, and the wiring on the glass component had a line width of 300 μm and an electrode height of 750 nm. Flexible Circuit Board (FPC): An FPC was prepared, including a resin film substrate based on polyethylene terephthalate (PET) and wiring provided on the resin film substrate. The wiring of this FPC included electrodes consisting of a Cu layer with a pitch of 70 μm (space 35 μm, electrode width 35 μm, thickness 18 μm), a 0.5 μm thick Ni layer, and a 2.5 μm thick Au layer formed in that order on the Cu layer.

[0103] (Preparation of connection structure) An adhesive film was placed on a glass member, and an FPC was placed on the adhesive film to prepare a laminate of the glass member, adhesive film, and FPC. At this time, the main surface of the glass substrate (the surface on which the wiring was formed) and the main surface of the resin film substrate (the surface on which the wiring was formed) were arranged to face each other. In addition, the first adhesive layer side of the adhesive film was arranged to contact the glass member. A silicone rubber cushion material was placed on the surface of the FPC side of the prepared laminate, and a connection structure was prepared by heating and pressurizing the cushion material using a thermocompression bonding device (heating method: pulse heat type, manufactured by Ohashi Manufacturing Co., Ltd.). The heating temperature was 120°C, the pressurizing pressure was 14 MPa, and the heating and pressurizing times were 30 seconds. Here, the heating temperature refers to the set temperature of the thermocompression bonding device, and the pressurizing pressure refers to the pressure relative to the total connection area.

[0104] (Connection reliability under high temperature and high humidity conditions) The obtained connection structure was subjected to a reliability test at 85°C and 85% RH. Specifically, first, the initial connection resistance between the electrodes of the glass member and the electrodes of the FPC in the connection structure was measured by the four-terminal method using a digital multimeter. Next, the connection structure was left in an environment of 85°C temperature and 85% RH for 100 hours, and then the connection resistance (connection resistance after 100 hours) was measured using the same method as for the initial connection resistance. In addition, the connection resistance increase rate was calculated using the following formula. The results are shown in Table 1. Connection resistance increase rate (%) = {(connection resistance after 100 hours - initial connection resistance) / initial connection resistance} × 100

[0105] Examples 2 to 8 and Comparative Examples 1 to 4 Adhesive films and connection structures were prepared and their connection reliability was investigated in the same manner as in Example 1, except that the conductive particles A1 were replaced with the same amounts of conductive particles A2 to A8 and a1 to a4 prepared by the above method. The results are shown in Table 1.

[0106]

[0107] 1...adhesive film, 1A...first adhesive layer, 1B...second adhesive layer, 2, 2A, 2B...adhesive component, 3, 3A, 30A, 30B...conductive particles, 4...first electronic component, 5...second electronic component, 6...connection portion, 7...insulating material, 10...connection structure, 31...core, 32A, 32B...conductive layer, 32a...first conductive layer, 32b...second conductive layer, 33, 33A, 33B...projection portion, 41...first substrate, 42...first electrode, 51...second substrate, 52...second electrode.

Claims

1. A conductive material containing conductive particles having a plurality of protrusions on the surface, the compression hardness of the conductive particles at 20% compression being 350 kgf / mm ２ ~1500kgf / mm ２ a ratio of an area of ​​the plurality of protrusions to an area of ​​a surface of the conductive particle is 30% or more.

2. A connection structure comprising: a first electronic component having a first electrode; a second electronic component having a second electrode; and a connection portion disposed between the first electronic component and the second electronic component and electrically connecting the first electrode and the second electrode to each other, wherein the connection portion comprises a cured product of the adhesive composition described in claim 1.

3. The connection structure according to claim 2, wherein at least one of the first electrode and the second electrode has a surface layer containing Au.

4. The connection structure according to claim 3, wherein the thickness of the surface layer is 3 μm or less.

5. A method for manufacturing a connection structure, comprising the steps of: placing the adhesive composition described in claim 1 between a first electronic component having a first electrode and a second electronic component having a second electrode; and thermocompression bonding the first electronic component and the second electronic component via the adhesive composition to electrically connect the first electrode and the second electrode to each other.

6. The method for manufacturing a connection structure according to claim 5, wherein at least one of the first electrode and the second electrode has a surface layer containing Au.

7. The method for producing a connection structure according to claim 6, wherein the thickness of the surface layer is 3 μm or less.

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