Adhesive composition and connection structure

Abstract

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

Description

Technical Field

[0001] This invention relates to an adhesive composition and a connecting structure. Background Technology

[0002] In applications such as micro-OLEDs used in AR / VR, anisotropic conductive films are used to connect electronic components and electrodes for micro-circuits. Anisotropic conductive films are formed, for example, by dispersing conductive particles within an adhesive film. By sandwiching this anisotropic conductive film between opposing electrodes and subjecting it to heating and pressure, the insulation between adjacent electrodes on the same substrate can be maintained, while the opposing electrodes are electrically connected to each other.

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

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

[0005] Previous technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2000-286299

[0008] Patent Document 2: International Publication No. 2018 / 199329 Summary of the Invention

[0009] The technical problem to be solved by the invention

[0010] According to the research of the inventors, the electrode of at least one of the two connected electronic components 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). It has been established that when the thickness of the soft conductive layer is thin, the connection resistance between the connected electronic components tends to increase during prolonged exposure to high temperature and humidity conditions (e.g., temperature 85°C and humidity 85%) compared to when the soft conductive layer is thick. In adhesive compositions, it is required that the increase in resistance be suppressed even when used to connect such electronic components (to ensure excellent connection reliability).

[0011] Therefore, one aspect of the present invention aims to provide an adhesive composition having a soft conductive layer on its outermost surface and exhibiting excellent connection reliability when used to connect electrodes with a thin conductive layer.

[0012] means for solving technical problems

[0013] To address the aforementioned issues, research has revealed that when the thickness of the outermost soft conductive layer of the electrode is thick, it deforms in accordance with the shape of the conductive particles under heating and pressure during installation. As a result, the electrode and the conductive particles have a wide contact area, leading to stable and good conductivity. In contrast, when the thickness of the outermost soft conductive layer of the electrode is thin, the conductive layer is not easily deformed, resulting in a small contact area between the electrode and the conductive particles. This, in turn, causes the connection resistance to easily increase under high temperature and high humidity conditions.

[0014] Therefore, the inventors attempted to increase the contact area between the electrode and the conductive particles by reducing the compressive stiffness of the conductive particles and flattening them under pressure. However, if the compressive stiffness of the conductive particles is too low, the protrusions of the conductive particles cannot be fully embedded in the electrode, and it has been clearly shown that good conductivity is sometimes not achieved.

[0015] The inventors further conducted in-depth research and discovered that by setting the ratio of the compressibility of the conductive particles to the area of ​​the protrusions of the conductive particles to a specific range, the contact area between the electrode and the conductive particles can be fully ensured, and the protrusions of the conductive particles are fully embedded in the electrode surface. As a result, the connection reliability under high temperature and high humidity conditions can be improved, thus completing the present invention.

[0016] The present invention provides, in several aspects, the following [1] to [7].

[0017] [1] An adhesive composition containing conductive particles having a plurality of protrusions on their surface, wherein the conductive particles have a compressive hardness of 350 kgf / mm² at 20% compression. 2 ~1500kgf / mm 2The area of ​​multiple protrusions is more than 30% of the surface area of ​​the conductive particles.

[0018] [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, the connection portion comprising a cured product of the adhesive composition described in [1].

[0019] [3] According to the connection structure described in [2], at least one of the first electrode and the second electrode has a surface layer containing Au.

[0020] [4] According to the connection structure described in [3], the thickness of the surface layer is less than 3 μm.

[0021] [5] A method for manufacturing a connecting structure includes the following steps: disposing of 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 thermally pressing the first electronic component and the second electronic component together through the adhesive composition to electrically connect the first electrode and the second electrode to each other.

[0022] [6] In the method of manufacturing the connecting structure according to [5], at least one of the first electrode and the second electrode has a surface layer containing Au.

[0023] [7] The manufacturing method of the connecting structure according to [6] wherein the thickness of the surface layer is less than 3 μm.

[0024] Invention Effects

[0025] According to one aspect of the invention, an adhesive composition can be provided having a soft conductive layer on its outermost surface and exhibiting excellent connection reliability when used to connect electrodes with a thin conductive layer. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view showing one embodiment of the adhesive film.

[0027] Figure 2 This is a schematic cross-sectional view representing one embodiment of conductive particles.

[0028] Figure 3 This is a schematic cross-sectional view showing another embodiment of the adhesive film.

[0029] Figure 4 This is a schematic cross-sectional view showing one embodiment of the connecting structure.

[0030] Figure 5This is a schematic cross-sectional view illustrating one embodiment of a method for manufacturing a connecting structure. Detailed Implementation

[0031] Hereinafter, with appropriate reference to the accompanying drawings, the embodiments of the present invention will be described in detail.

[0032] <Adhesive Composition>

[0033] One embodiment of an adhesive composition includes conductive particles having multiple protrusions on their surface, the conductive particles having a compressive hardness of 350 kgf / mm² at 20% compression. 2 ~1500kgf / mm 2 The area of ​​the protrusion is more than 30% of the surface area of ​​the conductive particle.

[0034] Adhesive compositions typically also contain an adhesive component in which conductive particles are dispersed. The adhesive composition can be in the form of a paste or a film. Figure 1 This is a schematic cross-sectional view illustrating one embodiment of a film-like adhesive composition (adhesive film). For example... Figure 1 As shown, in one embodiment, the adhesive film 1 is composed of a monolayer formed by an adhesive component (insulating adhesive) 2 and conductive particles 3 dispersed in the adhesive component 2.

[0035] Figure 2 This is a schematic cross-sectional view illustrating one embodiment of the conductive particle 3. (e.g.) Figure 2 As shown in (a), in one embodiment, the conductive particle 30A has a non-conductive core 31 and a conductive layer 32A covering the core 31.

[0036] Preferably, the surface of the core 31 is substantially entirely covered by the conductive layer 32A, but within the scope of maintaining the function of electrically connecting electronic components to each other, a portion of the surface of the core 31 may be exposed without being covered by the conductive layer 32A.

[0037] The core 31 is formed of a non-conductive material such as glass, ceramic, or resin, preferably resin. Examples of resins include acrylic resin, styrene resin, silicone resin, polybutadiene resin, and copolymers of monomers constituting these resins. The core 31 may be a particle containing a polymer, which contains at least one monomer selected from styrene and divinylbenzene as a monomer unit. The polymer may also contain (meth)acrylate as a monomer unit. The average diameter of the core 31 may be, 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.

[0038] The conductive layer 32A is formed, for example, by a single conductive layer. The conductive layer 32A is formed, for example, by Ni, Cu, Ag, Ru, or Pd, or by an alloy containing these metallic elements. The alloy can be, for example, an alloy containing Ni (Ni alloy). Examples of Ni alloys include Ni-B, Ni-P, and Ni-WB. From the viewpoint of further suppressing the reduction in connection reliability when using electrodes with a thin outermost soft conductive layer, the conductive layer 32A is preferably formed of Pd. The thickness of the conductive layer 32A can be, for example, 50 nm or more, or 300 nm or less. The thickness of the conductive layer 32A refers to the thickness of the portion of the conductive layer before the protrusions described later are formed. The thickness of the conductive layer 32A can be measured using an electron microscope.

[0039] like Figure 2 As shown in (b), in another embodiment of the conductive particle 30B, the conductive layer 32B can be a conductive layer composed of a first conductive layer 32a and a second conductive layer 32b. That is, the conductive particle 30B according to the other embodiment has a core 31, a first conductive layer 32a covering the core 31, and a second conductive layer 32b covering the first conductive layer 32a.

[0040] The first conductive layer 32a is formed, for example, by Ni. The second conductive layer 32b can be formed, for example, by Au or Pd. That is, the conductive particle 30B may have a layer formed of Au or Pd as a conductive layer on the outermost surface of the conductive particle 30B.

[0041] The thickness of the first conductive layer 32a can be, for example, 50 nm or more, or 300 nm or less. The thickness of the second conductive layer 32b can be, for example, 2 nm or more, 5 nm or more, or 10 nm or more, or 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 refer to the thickness of the portion of the conductive layer before the protrusions described later are formed. The thicknesses of the first conductive layer 32a and the second conductive layer 32b can be measured using an electron microscope.

[0042] Multiple protrusions 33 are formed on the surface of the conductive particle 3. Figure 2 In the conductive particle 30A shown in (a), the protrusion 33A is composed of a conductive layer 32A formed by one layer. Figure 2 (b) In the conductive particle 30B shown, the protrusion 33B is composed of a conductive layer 32B formed by two layers: a first conductive layer 32a and a second conductive layer 32b.

[0043] The ratio of the area of ​​the plurality of protrusions 33 to the surface area of ​​the conductive particle 3 (hereinafter also referred to as the "area ratio of the protrusions") is 30% or more. From the viewpoint of increasing the contact area between the conductive particle and the electrode and further improving the connection reliability, the area ratio of the protrusions can be 32% or more, 35% or more, 38% or more, or 40% or more. Furthermore, the area ratio of the protrusions can be 70% or less, 65% or less, 60% or less, or 55% or less.

[0044] The area ratio of the protrusion is determined by analyzing a black-and-white SEM image of the conductive particle 3, which is generated using a scanning electron microscope (SEM). The analysis of the SEM image can be performed using the method described in Japanese Patent Application Publication No. 2016-61722. Specifically, it can be determined by a method including the following steps: detecting the boundary between the projection image of each conductive particle 3 and other regions, i.e., the particle edge, in an SEM image of multiple conductive particles 3; calculating a second threshold corresponding to the boundary between the protrusion and other regions based on the degree distribution of brightness in the region inside the particle edge; binarizing the region inside the particle edge using the obtained second threshold to generate a binarized image; calculating the ratio of the area of ​​the region corresponding to the protrusion to the area of ​​the region inside the particle edge in the obtained binarized image as the area ratio of the protrusion of each conductive particle 3; and calculating the average value of the area ratio of the protrusion calculated for 100 conductive particles 3.

[0045] In the analysis of the SEM image described above, the particle edge essentially corresponds to the outer periphery of the two-dimensional projection image of the conductive particle 3, including the concave and convex features originating from the protrusion. The degree distribution of brightness obtained from the SEM image typically represents the minimum value of the portion reflecting the particle edge. The brightness corresponding to this minimum value is used as the first threshold to binarize the SEM image, generating a binarized image. The edges formed in the obtained binarized image are detected as particle edges. Based on the particle edges, the center coordinates of the conductive particle 3 on the SEM image are calculated. A circle fitted to the particle edge is obtained using the least squares method, the center of this circle is set as the center coordinates of the conductive particle 3, and the radius of this circle is calculated as r. Furthermore, a circular region with a radius of r / 2 centered at this center coordinate is determined as the region inside the particle edge.

[0046] In the brightness distribution within the region inside the particle edge, typically, the low brightness side primarily reflects the brightness values ​​of pixels encompassing the region of the particle surface and protrusions excluding the edges, while the high brightness side primarily reflects the brightness values ​​of pixels encompassing the region of the protrusion's edge portion. Furthermore, the low brightness side exhibits a peak representing the brightness of the particle surface and protrusions excluding the edges, while the high brightness side exhibits a portion with the largest rate of decrease in brightness, indicating a sharp decrease in the brightness of the particle surface and protrusions excluding the edges. Based on this brightness distribution, the second threshold is selected from the brightness value corresponding to the maximum value of the brightness present on the low brightness side and the brightness value corresponding to the portion with the largest rate of decrease in brightness present on the high brightness side. More specifically, the second threshold is set as the brightness value between the brightness value corresponding to the maximum value of the brightness present on the low brightness side and the brightness value corresponding to the point with the largest rate of decrease in brightness present on the high brightness side. Based on the second threshold, a binarized image of the region inside the particle edge is generated, and the ratio of the area of ​​the white region in the binarized image to the area of ​​the region inside the particle edge is calculated as the area ratio of the protrusion of each conductive particle 3.

[0047] The average height of the multiple protrusions 33 can be above 50nm, above 70nm, above 90nm, above 110nm, or above 130nm, or below 1200nm, below 1000nm, below 600nm, below 500nm, below 400nm, below 300nm, below 200nm, or below 150nm.

[0048] The average height of the multiple protrusions 33 can also be determined by analyzing the SEM image of the conductive particles according to the method described in Japanese Patent Application Publication No. 2016-61722. Specifically, for example, it can be determined by a method including the following steps: detecting the boundary between the projected image of each conductive particle 3 and other regions, i.e., the particle edge, in the SEM image of multiple conductive particles 3; calculating the center coordinates of the conductive particles 3 in the SEM image based on the particle edges; dividing the particle edges into 18 particle edge portions such that regions with an angle of 40 degrees in polar coordinates centered on the center coordinates are offset by 20 degrees; for each particle edge portion, calculating the difference between the maximum and minimum distances between the center coordinates and the particle edge, and calculating the average of their differences as the average height of the protrusions 33; and for 100 conductive particles 3, calculating the average height of the protrusions 33, and calculating their average values.

[0049] In the analysis of the SEM images above, the maximum distance between the center coordinates of each particle's edge and the particle's edge was calculated by selecting three points with the largest distance from the center coordinates, taking the points constituting the edge of each particle as the target, and calculating their average value. Similarly, the minimum distance between the center coordinates of each particle's edge and the particle's edge was calculated by selecting three points with the smallest distance from the center coordinates, taking the points constituting the edge of each particle as the target, and calculating their average value.

[0050] The average particle size of the conductive particles 3 can 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, or it can be less than 10 μm, 8.0 μm or less, 6.0 μm or less, 5.0 μm or less, or 4.0 μm or less. In this specification, for any 300 conductive particles 3, the particle size is determined by observation using a scanning electron microscope (SEM), and the average value of the obtained particle size is taken as the average particle size. More specifically, the average particle size of the conductive particles 3 is calculated as follows: In the SEM image of the conductive particles 3, as described above, the circle fitted to the particle edge of each conductive particle 3 is obtained by the least squares method, and the diameter of the circle is taken as the particle size of each conductive particle 3. The average value of this particle size of the 300 conductive particles 3 is then calculated.

[0051] The compressive hardness of conductive particle 3 at 20% compression is 350 kgf / mm². 2 ~1500kgf / mm 2 The compressive hardness of conductive particle 3 at 20% compression is 380 kgf / mm². 2 Above, 400kgf / mm 2 Above, 420kgf / mm 2 Above or 450 kgf / mm 2 The above can also be 1300 kgf / mm 2 Below, 1200kgf / mm 2 Below, 1100kgf / mm 2 Below, 1000kgf / mm 2 Below, 900kgf / mm 2 Below or 800 kgf / mm 2 The greater the compressive hardness of the conductive particles 3, the easier it is to embed the protrusions of the conductive particles into the electrode surface when the adhesive composition is used as an anisotropic conductive adhesive composition, which is therefore preferable. On the other hand, the lower the compressive hardness of the conductive particles, the easier it is for the conductive particles to flatten when the adhesive composition is used as an anisotropic conductive film, and the easier it is to increase the contact area between the electrode and the conductive particles, which is also preferable.

[0052] The compressive hardness (hereinafter sometimes referred to as "K value") of the conductive particle 3 was determined using a surface hardness compression measuring apparatus (e.g., FISCHER INSTRUMENTS KK, HM2000). Specifically, firstly, the conductive particles 3 were dispersed on a glass slide (MATSUNAMI GLASS IND., LTD., S1214) on a stage set at 25°C. Then, one conductive particle 3 was selected from the dispersed conductive particles 3, and the stress-strain curve was obtained using a diamond indenter with a square base of 50 μm on one side, based on an initial load of 0.1 mN and a compression rate of 0.33 mN / s from the center. Specifically, the compressive hardness of the elastic sphere could be determined using the formula F = (2πf / σ) * ... 1 / 2 / 3)×(S 3 / 2 )×(E×R 1 / 2 ) / (1-σ 2 ), and according to the following formula K=E / (1-σ 2 ) = (3 / 2) 1 / 2 )×F×(S -3 / 2 )×(R -1 / 2 The value of K can be calculated using the following formula: K = 3000F / (D). Alternatively, if we set the deformation rate as X (%) and the diameter of the sphere as D (μm), then the value of K for any deformation rate can be calculated using the following formula: K = 3000F / (D). 2 ×X 3 / 2 )×10 6 The deformation rate X is calculated using the following formula: X = (S / D) × 100. The compression hardness of conductive particle 3 at 20% compression refers to the K value when the deformation rate X is 20 (%). The maximum test load in the compression test is set, for example, to 50 mN.

[0053] The recovery rate of conductive particles 3 can be above 10%, above 20%, above 25%, or above 30%, or it can be below 100%, below 90%, below 80%, below 75%, or below 70%.

[0054] The recovery rate of the conductive particles 3 was measured using a surface hardness compression measuring apparatus (e.g., manufactured by FISCHER INSTRUMENT SK.K., HM2000). Specifically, firstly, the conductive particles 3 were dispersed on a glass slide (manufactured by MATSUNAMIGLASS IND., LTD., S1214) on a stage set at 25°C. Then, one conductive particle 3 was selected from the dispersed conductive particles 3, and a diamond indenter with a square base of 50 μm on one side was used. The initial load was set to 0.1 mN, and the particle was compressed from the center at a rate of 0.33 mN / s until a load of 5 mN was applied. Conversely, the load was reduced to the initial load value at a rate of 0.33 mN / s. Here, the displacement of the conductive particle 3 from the initial load (load 0.1mN) to the load reversal (load 5mN) is defined as L2, and the displacement of the conductive particle 3 from the load reversal to the final load (load 0.1mN) is defined as L1. The value of L1 / L2×100 (%) is then calculated as the recovery rate of the conductive particle 3. By performing this operation on 10 conductive particles 3 and taking the average value, the recovery rate of the conductive particle 3 in this embodiment is calculated.

[0055] The conductive particles 3 having the protrusions described above can be obtained, for example, by forming conductive layers 32A and 32B on the surface of the core 31 through metal plating. During metal plating, the thickness of the conductive layers 32A and 32B can be changed by altering the plating conditions, thereby forming the protrusions 33. For example, during the metal plating process, the protrusions 33 can be formed by progressively increasing the concentration of the plating solution.

[0056] Alternatively, by adjusting the pH of the plating bath, for example, setting the pH of the nickel plating bath to 6, a conductive layer with bump-shaped protrusions can also be formed (see Mochizuki et al., Surface Technology, Vol. 48, No. 4, pp. 429-432, 1997). When glycine is used as a complexing agent to contribute to the stability of the plating bath, a conductive layer with a flat surface is formed; conversely, when tartaric acid or DL-malic acid is used as a complexing agent, bump-shaped protrusions are formed (see, for example, Ogihara et al., Amorphous Plating, Vol. 36, pp. 35-37, 1994; Ogihara et al., Journal of the Institute of Circuit Installation, Vol. 10, No. 3, pp. 148-152, 1995). By employing these methods, conductive layers 32A and 32B with protrusions 33 can be formed.

[0057] In production Figure 2 In the case of conductive particles 30B as shown in (b), for example, after forming a first conductive layer 32a with protrusions by the above method, a layer of Au or Pd is formed by substitution plating, thereby obtaining a second conductive layer 32b.

[0058] Regarding the area ratio of the protrusions in the conductive particles 3, it can be adjusted, for example, during the metal plating process, by adjusting the concentration of the plating solution in stages. For example, the reaction can be promoted and the area ratio of the protrusions increased by rapidly increasing the concentration of the plating solution. Furthermore, regarding the compressive hardness of the conductive particles, for example, when the core is formed with resin, it can be adjusted by appropriately adjusting the type of resin (if the resin is a copolymer, the copolymerization ratio of the monomers is adjusted).

[0059] Furthermore, the conductive particles 3 having the protrusions described above can also be obtained, for example, by depositing an insulating or conductive core material on the surface of the core body 31 and then forming conductive layers 32A and 32B by metal plating. In this case, the area ratio of the protrusions in the conductive particles 3 can be adjusted, for example, according to the amount of core material disposed on the surface of the core body 31.

[0060] Based on the total mass of the solid components in the adhesive composition, the content of conductive particles 3 can be 5% or more by mass, 10% or more by mass, or less than 30% by mass or less than 25% by mass.

[0061] Based on the total volume of solid components in the adhesive composition, the content of conductive particles 3 can be more than 1% by volume, or less than 50% by volume or less than 40% by volume.

[0062] Adhesive component 2 is, for example, composed of a material that is insulating and exhibits curing properties by heat or light. Adhesive component 2 may contain polymerizable substances having functional groups that can be polymerized by free radicals. Examples of polymerizable substances include (meth)acrylates.

[0063] Examples of (meth)acrylates include (poly)urethane (meth)acrylates, meth (meth)acrylates, ethyl (meth)acrylates, isopropyl (meth)acrylates, isobutyl (meth)acrylates, ethylene glycol diacrylates, diethylene glycol diacrylates, triethylene glycol diacrylates, dimethyloltricyclodecane diacrylates, trimethylolpropane triacrylates, tetramethylolmethane tetraacrylates, 2-hydroxy-1,3-diacryloyloxypropane, 2,2-bis[4-(acryloyloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloyloxypolyethoxy)phenyl]propane, dicyclopentenyl acrylates, tricyclodecyl acrylates, bis(acryloyloxyethyl)isocyanurate, ε-caprolactone-modified tri(acryloyloxyethyl)isocyanurate, tri(acryloyloxyethyl)isocyanurate, and ethylene oxide-modified di(meth)acrylate phosphates. When ethylene oxide-modified di(meth)acrylate is used as a (meth)acrylate, the adhesive strength of the adhesive composition can be further improved.

[0064] Adhesive component 2 may contain only (meth)acrylate as a polymerizable substance, or it may contain other polymerizable substances besides (meth)acrylate. A polymerizable substance is a substance having functional groups that can polymerize via free radicals. Maleimide compounds are examples of other polymerizable substances.

[0065] Based on the total mass of adhesive component 2, the content of polymeric substances can be 10% or more by mass, 20% or more by mass, 30% or more by mass, or 40% or more by mass, or it can be less than 80% by mass, less than 70% by mass, less than 60% by mass, or less than 50% by mass.

[0066] Adhesive component 2 may contain a curing agent (thermal free radical polymerization initiator). The curing agent is a compound that generates free radicals through thermal decomposition.

[0067] Examples of curing agents include peroxides and azo compounds. Examples of peroxides include diacyl peroxides such as dioctanoyl peroxide, dilauryl peroxide, distearyl peroxide, and dibenzoyl peroxide; dicarbonates such as bis(4-tert-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate; tert-butyl peroxyneopentate, tert-hexyl peroxyneopentate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, tert-hexyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-hexyl peroxyisopropyl monocarbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, and tert-butyl... Peroxides including laurate peroxide, tert-butylperoxy-2-ethylhexyl monocarbonate, tert-butylperoxybenzoate, tert-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, and tert-butylperoxyacetate; peroxides including ketals including 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-2-methylcyclohexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-hexylperoxy)cyclohexane, and 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane; dialkyl peroxides including dialkyl peroxide, tert-butylisopropylbenzene peroxide, and di-tert-butyl peroxide; and hydroperoxides including p-menthane hydroperoxide.

[0068] Examples of azo compounds include 2,2'-azobis(2,4-dimethylpentanonitrile) and 2,2'-azobisisobutyronitrile.

[0069] As a curing agent, one of the above-mentioned peroxides and azo compounds can be used alone, or two or more can be used in combination. The adhesive component preferably includes at least one of diacyl peroxide and peroxide ester as a curing agent. The 1-minute half-life temperature of the diacyl peroxide and peroxide ester can be independently between 90 and 175°C. Furthermore, the molecular weight of the diacyl peroxide and peroxide ester can be independently between 180 and 1000.

[0070] Based on the total mass of adhesive component 2, the content of the curing agent can be 0.05% or more by mass, 0.1% or more by mass, 1% or more by mass, or 2% or more by mass, or less than 20% by mass, less than 10% by mass, or less than 8% by mass.

[0071] Adhesive component 2 may contain a thermoplastic resin. Examples of thermoplastic resins include polyamide resins, phenoxy resins, (meth)acrylic resins, polyimide resins, polyester resins, polyurethane resins, polyester urethane resins, and polyvinyl butyral resins. These thermoplastic resins may be used alone or in combination of two or more.

[0072] Based on the total mass of adhesive component 2, the content of thermoplastic resin can be above 20% by mass or below 50% by mass.

[0073] Adhesive component 2 may also include curing modifiers, adhesive imparting agents, coupling agents (silane coupling agents, etc.), ion trapping agents, color developers, dispersants, photoradical polymerization initiators, fillers, and other components. Based on the total mass of the adhesive components, the content of other components may be, for example, more than 1% by mass or less than 20% by mass.

[0074] In another embodiment, the adhesive film may have two or more regions. The adhesive film may include: a first region containing a first adhesive component; and a second region adjacent to the first region and containing a second adhesive component. The first region and the second region may each be a layer.

[0075] For example, such as Figure 3As shown, the adhesive film 1 can be a two-layer structure comprising a layer 1A containing conductive particles 3A (a first adhesive layer formed by adhesive component 2A and conductive particles 3A dispersed in adhesive component 2A) and a layer 1B not containing conductive particles (a second adhesive layer formed by adhesive component 2B) 1B. In this case, the first adhesive layer 1A may contain the aforementioned polymeric substance, curing agent, curing modifier, thermoplastic resin, conductive particles, and other components as needed. Furthermore, the second adhesive layer 1B may contain the aforementioned polymeric substance, curing agent, curing modifier, 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.

[0076] The content of polymeric substances, curing agents, curing modifiers, thermoplastic resins, and other components in the first and second adhesive layers can be independently the same as the content of each component in the adhesive composition described above. In this case, the phrase "based on the total mass of the adhesive components" is replaced with "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".

[0077] The number density of conductive particles 3 in the adhesive film 1 can be 1000 particles / mm². 2 Above, 3000 pieces / mm 2 Above, 5000 pieces / mm 2 Above, 7000 pieces / mm 2 More than or 8000 pieces / mm 2 The above can also be 15,000 pieces / mm 2 Below, 13,000 pieces / mm 2 Below, 12000 pieces / mm 2 Below or 11,000 pieces / mm 2 The number density of conductive particles 3 was determined by counting the number of conductive particles 3 per unit area of ​​the adhesive film 1 using an electron microscope.

[0078] The thickness of the adhesive film 1 can be, for example, 5 μm or more or 10 μm or more, or less than 50 μm, less than 30 μm or less than 20 μm.

[0079] The adhesive composition (adhesive film 1) can be a conductive adhesive composition (conductive adhesive film) or an anisotropic conductive adhesive composition (anisotropic conductive adhesive film). The adhesive composition is preferably used in the manufacture of the connecting structure.

[0080] <Connection Structure>

[0081] One embodiment of the connection structure 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, which electrically connects the first electrode and the second electrode to each other, wherein the connection portion comprises a cured product of the adhesive composition described above.

[0082] Figure 4 This is a schematic cross-sectional view illustrating one embodiment of the connecting structure. For example... Figure 4 As shown, the connecting structure 10 includes a first electronic component 4 and a second electronic component 5 that are opposite to each other, and a connecting portion 6 that connects the first electronic component 4 and the second electronic component 5 between them.

[0083] The first electronic component 4 includes a first substrate 41 and a first electrode 42 formed on the main surface 41a of the first substrate 41. The second electronic component 5 includes a second substrate 51 and a second electrode 52 formed on the main surface 51a of the second substrate 51.

[0084] There are no particular limitations on the first electronic component 4 and the second electronic component 5, as long as they are components that have electrodes that require electrical connection. Examples of components with electrodes include active components such as diodes, semiconductor chips, transistors, and thyristors, passive components such as capacitors, resistors, and coils, and substrates with electrodes such as printed circuit boards.

[0085] The first substrate 41 and the second substrate 51 can be silicon substrates, glass substrates, flexible substrates, etc. The flexible substrate may, for example, contain at least one thermoplastic resin selected from the group consisting of polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC) and polyethylene naphthalate (PEN).

[0086] 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, conductors such as silver nanowires and carbon nanotubes. The first electrode 42 and the second electrode 52 can be formed from the same material or from different raw materials.

[0087] In one embodiment, the first electrode 42 may have a base layer disposed on the first substrate 41 and a surface layer disposed on the base layer. In another embodiment, the second electrode 52 may have a base layer disposed on the second substrate 51 and a surface layer disposed on the base layer. These surface layers are respectively located on the outermost surfaces of the first electrode 42 and the second electrode 52. Either the first electrode 42 or the second electrode 52 may have a base layer and a surface layer, or both the first electrode 42 and the second electrode 52 may have a base layer and a surface layer.

[0088] The base layer may contain, for example, a hard metal such as Ni. The surface layer may contain, for example, a soft metal such as Au or Pd. The hardness of the surface layer may be less than that of the base layer.

[0089] The thickness of the surface layer can be 0.005 μm or more, or 0.01 μm, or 5 μm or less, or 3 μm or less. In the adhesive film according to one embodiment, since the compressive hardness of the conductive particles and the area ratio of the protrusions of the conductive particles are within a specific range, even when the electrode has a base layer formed of hard metal and the surface layer is thin, the contact area between the electrode and the adhesive film becomes sufficiently wide, and the protrusions of the conductive particles are easily embedded in the electrode.

[0090] In the first electronic component 4 and the second electronic component 5, one first electrode 42 or one second electrode 52 may be provided, but it is preferable to provide multiple electrodes at predetermined intervals.

[0091] The connecting portion 6 contains a cured material containing adhesive components, namely an insulating material 7, and conductive particles 3. The conductive particles 3 are disposed not only between the opposing first electrode 42 and second electrode 52, but also between the main surface 41a of the first substrate 41 and the main surface 51a of the second substrate 51. In the connecting structure 10, the first electrode 42 and the second electrode 52 are electrically connected by the conductive particles 3. That is, the conductive particles 3 are in contact with both the first electrode 42 and the second electrode 52.

[0092] In the connection structure 10, as described above, the opposing first electrode 42 and second electrode 52 are electrically connected by conductive particles 3. Therefore, the connection resistance between the first electrode 42 and the second electrode 52 is significantly reduced. Consequently, the flow of current between the first electrode 42 and the second electrode 52 is smooth, thereby fully utilizing the functions of the first electronic component 4 and the second electronic component 5.

[0093] <Manufacturing Method of Connecting Structures>

[0094] The aforementioned connection structure can be manufactured by a method comprising the following steps: the method comprising: disposing the aforementioned adhesive composition between a first electronic component having a first electrode and a second electronic component having a second electrode; and thermally pressing the first electronic component and the second electronic component together via the adhesive composition to electrically connect the first electrode and the second electrode to each other.

[0095] Figure 5 This is a schematic cross-sectional view illustrating one embodiment of a manufacturing method for a connecting structure. For example... Figure 5As shown in (a), firstly, an adhesive film 1 (a film-like adhesive composition) is disposed on the main surface 41a of the first electronic component 4. When the adhesive film 1 is laminated onto a substrate (not shown), the laminate of the substrate and the adhesive film 1 is disposed on the first electronic component 4 such that the adhesive film 1 side of the substrate faces the first electronic component 4. Figure 3 As shown, when the adhesive film 1 has a first adhesive layer 1A and a second adhesive layer 1B, from the viewpoint of increasing the number of conductive particles captured between the opposing electrodes, it is preferable to configure the first adhesive layer 1A side to be in contact with the main surface 41a of the first electronic component 4.

[0096] After the adhesive film 1 is placed on the main surface 41a of the first electronic component 4, the laminate of the adhesive film 1 and the first electronic component 4 is pressed along the lamination direction to temporarily connect the adhesive film 1 to the first electronic component 4. At this time, heating can be performed simultaneously with pressing.

[0097] Next, as Figure 5 As shown in (b), the second electronic component 5 is further disposed on the adhesive film 1 disposed on the first electronic component 4, such that the second electrode 52 side faces the first electronic component 4 (i.e., the first electrode 42 and the second electrode 52 are arranged opposite each other and the adhesive film 1 is disposed between the first electronic component 4 and the second electronic component 5). When the adhesive film 1 is laminated on a substrate (not shown), the second electronic component 5 is disposed on the adhesive film 1 after the substrate is peeled off.

[0098] Then, the first electronic component 4 and the second electronic component 5 are thermally bonded together using an adhesive film 1. Thermal bonding, for example, is achieved through... Figure 5 (b) Heating and pressurizing are performed in the direction of arrow A. Through heating and pressurizing in the direction of arrow A, the adhesive film 1 solidifies, and the first electrode 42 and the second electrode 52 become electrically connected. As a result, the following is obtained: Figure 4 The connection structure 10 shown.

[0099] The pressure applied during hot pressing can be, for example, above 5 MPa or below 20 MPa. The heating during hot pressing can be, for example, above 100°C or below 170°C, 150°C, or 130°C. The pressure application time and heating time during hot pressing can be, for example, above 10 seconds or below 60 seconds.

[0100] In the connection structure 10 obtained as described above, the conductive particles 3 can be brought into contact with the opposing first electrode 42 and second electrode 52, thereby sufficiently reducing the connection resistance between the first electrode 42 and the second electrode 52.

[0101] By heating and pressurizing the adhesive film 1, the adhesive component 2 solidifies into an insulating material 7 while the distance between the first electrode 42 and the second electrode 52 is sufficiently reduced, and the first electronic component 4 and the second electronic component 5 are firmly connected through the connecting part 6.

[0102] Example

[0103] The present invention will now be described in more detail with reference to embodiments. The present invention is not limited to any of these embodiments.

[0104] <Fabrication of Conductive Particles A1-A8 and a1-a4>

[0105] Conductive particles A1 to A8 and a1 to a4 were fabricated as follows.

[0106] (The creation of conductive particles A1)

[0107] Tetramethylolmethane tetraacrylate, divinylbenzene, and styrene were used as monomers and polymerized by suspension polymerization using a polymerization initiator (benzoyl peroxide), thereby obtaining a core (average particle size: 5.0 μm). Electroless Ni plating was applied to the core to obtain conductive particles having a protruding conductive layer (Ni layer, thickness: 60 nm) formed of Ni. By substitution plating, a layer with protruding Pd (Pd layer, thickness: 10 nm) was formed on the Ni layer of the conductive particles, thereby obtaining conductive particles A1.

[0108] (The creation of conductive particles A2)

[0109] Conductive particles A2 were obtained by electroless Ni plating on the nucleus (average particle size: 3 μm). The conductive particles A2 had protrusions and a conductive layer (Ni layer, thickness: 120 nm) formed of Ni.

[0110] (The creation of conductive particles A3)

[0111] Conductive particles A3 with a protrusion and a conductive layer (Ni layer, thickness: 140 nm) formed of Ni were obtained by electroless Ni plating on the nucleus (average particle size: 3.25 μm).

[0112] (The creation of conductive particles A4)

[0113] Conductive particles A4 with protrusions and a conductive layer formed by Ni-WB were fabricated by applying Ni-WB plating to the surface of the nucleus (average particle size: 3 μm).

[0114] (The fabrication of conductive particles A5)

[0115] By applying Pd plating to the surface of the nucleus (average particle size: 3 μm), conductive particles A5 with a Pd layer (Pd layer, thickness: 26 nm) having protrusions were obtained.

[0116] (The fabrication of conductive particles A6)

[0117] Conductive particles A6 with a protrusion and a conductive layer (Ni layer) formed of Ni were obtained by electroless Ni plating treatment on the nucleus (average particle size: 3 μm).

[0118] (The creation of conductive particles A7)

[0119] By applying Pd plating to the surface of the nucleus (average particle size: 3 μm), conductive particles A7 with a Pd layer (Pd layer, thickness: 24.4 nm) having protrusions and formed by a Pd conductive layer were obtained.

[0120] (The fabrication of conductive particles A8)

[0121] Conductive particles A8 with a protrusion and a conductive layer (Ni layer, thickness: 140 nm) formed of Ni were obtained by electroless Ni plating on the nucleus (average particle size: 5 μm).

[0122] (The fabrication of conductive particle a1)

[0123] Conductive particles a1 with protrusions and a conductive layer (Ni layer, thickness: 110 nm) formed of Ni were obtained by electroless Ni plating on the nucleus (average particle size: 3 μm).

[0124] (The creation of conductive particle a2)

[0125] Conductive particles with a protruding Ni layer were obtained by electroless Ni plating of the nucleus (average particle size: 3 μm). By substitution plating, a Pd layer with protruding Pd was formed on the Ni layer of the conductive particles, thereby obtaining conductive particles a2.

[0126] (The creation of conductive particles a3)

[0127] By applying Ni-P plating to the surface of the nucleus (average particle size: 3 μm), conductive particles a3 with an average area ratio and height of protrusions formed by Ni-P and protrusions with protrusions as shown in Table 1 were obtained.

[0128] (The creation of conductive particles a4)

[0129] Conductive particles a4 with a protrusion and a conductive layer (Ni layer, thickness: 120 nm) formed of Ni were obtained by electroless Ni plating on the nucleus (average particle size: 3.8 μm).

[0130] <Analysis of conductive particles A1~A8 and a1~a4>

[0131] (Area ratio of protrusions)

[0132] Conductive particles A1-A8 and a1-a4 were collected onto a carbon ribbon, and the collected conductive particles were photographed using a scanning electron microscope (SEM) to obtain SEM images containing each conductive particle. The SEM images were analyzed using the method described in the Specific Implementation section to determine the area ratio of the protrusions of conductive particles A1-A8 and a1-a4. The results are shown in Table 1.

[0133] (Compression hardness at 20% compression)

[0134] The compressive hardness of the conductive particles at 20% compression was determined using the following method. A micro-compression testing machine (FISCHER INSTRUMENTS KK, HM2000) was prepared, and conductive particles were dispersed on a glass slide (MATSUNAMI GLASS IND., LTD., S1214) on a stage set to 25°C. Then, one particle was selected from the dispersed conductive particles, and a diamond indenter with a square base of 50 μm on one side was used to obtain the stress-strain curve when the initial load was set to 0.1 mN and compression was performed from the center at a rate of 0.33 mN / s. The load value at 20% particle size deformation (20% compression) was read, and the compressive hardness of the conductive particles at 20% compression was calculated using the following formula. The results are shown in Table 1.

[0135] Compression hardness of conductive particles at 20% compression

[0136] =(3 / √2)×F 20 ×S 20 -3 / 2 ×R -1 / 2 ×10 -3

[0137] R: Radius of the conductive particle (μm), S 20 Displacement (mm) when compressed by 20%, F 20 Load (N) at 20% compression

[0138] <Example 1>

[0139] (Synthesis of polyurethane acrylate (UA1))

[0140] 2500 parts by weight (2.50 mol) of poly(1,6-hexanediol carbonate) (product name: DURANOL T5652, manufactured by ASAHI KASEI CORPORATION, number average molecular weight 1000) and 666 parts by weight (3.00 mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich Co. LLC) were uniformly added dropwise over 3 hours to a reaction vessel equipped with a stirrer, thermometer, reflux cooling tube with calcium chloride drying tube, and nitrogen inlet tube. Then, after fully introducing nitrogen into the reaction vessel, the reaction vessel was heated to 70–75°C to allow the reaction to proceed. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (manufactured by Sigma-Aldrich Co. LLC) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (manufactured by Sigma-Aldrich Co. LLC) were added to the reaction vessel, followed by 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (manufactured by Sigma-Aldrich Co. LLC), and the reaction was carried out at 70°C for 6 hours in air. This yielded polyurethane acrylate (UA1). The weight-average molecular weight of polyurethane acrylate (UA1) was 15,000. Furthermore, the weight-average molecular weight was determined by gel permeation chromatography (GPC) under the following conditions using a calibration curve based on standard polystyrene.

[0141] (Measurement conditions)

[0142] Device: Manufactured by Tosoh Corporation, GPC-8020

[0143] Detector: RI-8020 manufactured by Tosoh Corporation

[0144] Tube Column: Gelpack GLA160S+GLA150S manufactured by Resonac Techno Service Corporation

[0145] Sample concentration: 120 mg / 3 mL

[0146] Solvent: Tetrahydrofuran

[0147] Injection volume: 60μL

[0148] Pressure: 2.94 × 10⁶ Pa (30 kgf / cm²)

[0149] Flow rate: 1.00 mL / min

[0150] (Preparation method of polyester urethane resin)

[0151] 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were added to a stainless steel autoclave equipped with a stirrer, thermometer, capacitor, vacuum generator, nitrogen inlet pipe, and heater. 0.02 parts by mass of tetrabutoxytitanate as a catalyst were further added. The autoclave was then heated to 220°C under a nitrogen atmosphere and stirred for 8 hours. The pressure was then reduced to atmospheric pressure (760 mmHg) and cooled to room temperature. A white precipitate formed. The precipitate was removed, washed with water, and then vacuum dried to obtain a polyester polyol. The obtained polyester polyol was thoroughly dried, dissolved in MEK (methyl ethyl ketone), and added to a four-necked flask equipped with a stirrer, dropping funnel, reflux cooler, and nitrogen inlet pipe. Dibutyltin dilaurate was added as a catalyst in an amount of 0.05 parts by mass relative to 100 parts by mass of the polyester polyol. Subsequently, 4,4'-diphenylmethane diisocyanate, in an amount of 50 parts by mass relative to 100 parts by mass of polyester polyol, was dissolved in MEK and added using a dropping funnel, and stirred at 80°C for 4 hours to obtain polyester urethane resin.

[0152] (Preparation of the first adhesive composition)

[0153] As a polymerizing agent, the mixture comprises 17 parts by weight of dimethyloltricyclodecane diacrylate (product name: DCP-A, manufactured by KYOEISHACHEMICAL Co., LTD.), 30 parts by weight of the polyurethane acrylate synthesized as described above, and 1.5 parts by weight of ethylene oxide-modified dimethacrylate phosphate (product name: PM-21, manufactured by Nippon Kayaku Co., Ltd.). As a curing agent, it comprises 2.5 parts by weight of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (product name: PERHEXA25O, manufactured by NOF CORPORATION). As a thermoplastic resin, it comprises 45 parts by weight of the polyester urethane resin prepared as described above. As a silane coupling agent, it comprises 2.8 parts by weight of 3-glycidoxypropyltrimethoxysilane (product name: SH-6040, manufactured by Dow Corning Toray Co., Ltd.). As a filler, it comprises AEROSIL (product name: MR-202, manufactured by NIPPON AEROSIL CO., LTD.). The first adhesive composition was obtained by mixing 2.5 parts by weight of the conductive particles A1 produced by the above method with 2.5 parts by weight of the product (manufactured by LTD.). Furthermore, the content of the conductive particles was 4% by volume, based on the total volume of the first adhesive composition.

[0154] (Preparation of the second adhesive composition)

[0155] As a polymerizing agent, 30 parts by weight of dimethyloltricyclodecane diacrylate (product name: DCP-A, manufactured by KYOEISHACHEMICAL Co., LTD.), 27.5 parts by weight of the polyurethane acrylate synthesized as described above, and 2.5 parts by weight of ethylene oxide-modified dimethacrylate phosphate (product name: PM-21, manufactured by Nippon Kayaku Co., Ltd.) are mixed; 5.0 parts by weight of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (product name: PERHEXA25O, manufactured by NOF CORPORATION.) are used as a curing agent; and 27.5 parts by weight of the polyester urethane resin prepared as described above and phenoxy resin (product name: PHENOTHIAZINE ZX-1356-2, manufactured by NIPPON STEELChemical & Material Co., Ltd.) are used as the thermoplastic resin. The second adhesive composition was obtained by adding 15 parts by weight of 3-glycidoxypropyltrimethoxysilane (product name: SH-6040, manufactured by Dow Corning Toray Co., Ltd.) as a silane coupling agent, 5 parts by weight of AEROSIL (product name: R-202, manufactured by NIPPON AEROSIL CO., LTD.) as a filler.

[0156] A first adhesive layer was formed by applying a first adhesive composition to a substrate (a 50 μm thick PET film) using an applicator. A second adhesive layer was then formed using the same method as the first adhesive layer, employing a second adhesive composition. Finally, the first and second adhesive layers were laminated together using a laminator to form an adhesive film (14 μm thick).

[0157] (Determination of number density)

[0158] Using an electron microscope, the conductive particles contained in the fabricated adhesive film were examined for 1 mm. 2 The number of conductive particles in the adhesive film was determined by counting the number of particles. The results are shown in Table 1.

[0159] (Preparation of electronic components)

[0160] The following electronic components have been prepared.

[0161] • Glass components

[0162] A glass component comprising a glass substrate and Ti / Al / Ti wiring formed on the glass substrate was prepared. The glass substrate has a thickness of 0.7 mm, and the wiring in the glass component has a linewidth of 300 μm and an electrode height of 750 nm.

[0163] • Flexible printed circuit board (FPC)

[0164] An FPC was prepared, which has a resin film substrate based on polyethylene terephthalate (PET) and wiring disposed on the resin film substrate. The wiring of the FPC has electrodes consisting of a Cu layer with a spacing of 70 μm (35 μm interval, electrode width of 35 μm, and thickness of 18 μm) and an Ni layer with a thickness of 0.5 μm and an Au layer with a thickness of 2.5 μm sequentially formed on the Cu layer.

[0165] (Construction of connecting structures)

[0166] An adhesive film is deposited on a glass component, and an FPC (Flexible Printed Circuit) is deposited on the adhesive film to create a laminate of the glass component, adhesive film, and FPC. The glass substrate (the side with the wiring) and the resin film substrate (the side with the wiring) are positioned opposite each other. The first adhesive layer of the adhesive film is in contact with the glass component. A silicone rubber cushioning material is applied to the surface of the FPC side of the laminate. A hot-pressing device (heating method: pulse heating type, manufactured by OHASHI ENGINEERING Co., Ltd.) is used to heat and pressurize the cushioning material, thereby creating a connection structure. The heating temperature is 120°C, the pressurization pressure is 14 MPa, and the heating and pressurization times are 30 seconds. The heating temperature refers to the set temperature of the hot-pressing device, and the pressurization pressure refers to the pressure relative to the total connection area.

[0167] (Connection reliability under high temperature and high humidity conditions)

[0168] The obtained connection structure was subjected to a reliability test at 85°C and 85%RH. Specifically, firstly, using a digital multimeter and a four-terminal method, the initial connection resistance between the electrodes of the glass component and the FPC in the connection structure was measured. Next, the connection structure was placed in an environment of 85°C and 85%RH for 100 hours, and then the connection resistance (connection resistance after 100 hours) was measured using the same method as the initial connection resistance. Furthermore, the rate of increase in connection resistance was calculated using the following formula. The results are shown in Table 1.

[0169] Connection resistance rise rate (%)

[0170] ={(Connection resistance after 100 hours - Initial connection resistance) / Initial connection resistance} × 100

[0171] <Examples 2-8 and Comparative Examples 1-4>

[0172] Instead of conductive particle A1, the same amount of conductive particles A2 to A8 and a1 to a4, prepared by the above method, were used. Otherwise, the adhesive film and the connecting structure were prepared in the same manner as in Example 1, and the connection reliability was investigated. The results are shown in Table 1.

[0173] [Table 1]

[0174]

[0175] Symbol Explanation

[0176] 1-Adhesive film, 1A-First adhesive layer, 1B-Second adhesive layer, 2, 2A, 2B-Adhesive components, 3, 3A, 30A, 30B-Conductive particles, 4-First electronic component, 5-Second electronic component, 6-Connector, 7-Insulating material, 10-Connector structure, 31-Core, 32A, 32B-Conductive layers, 32a-First conductive layer, 32b-Second conductive layer, 33, 33A, 33B-Protrusions, 41-First substrate, 42-First electrode, 51-Second substrate, 52-Second electrode.

Claims

1. An adhesive composition comprising conductive particles having a plurality of protrusions on their surface, The compressibility of the conductive particles at 20% compression is 350 kgf / mm². 2 ~1500kgf / mm 2 , The area of ​​the plurality of protrusions is more than 30% of the surface area of ​​the conductive particle.

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

3. The connecting 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 less than 3 μm.

5. A method for manufacturing a connecting structure, comprising the following steps: The adhesive composition of claim 1 is disposed between a first electronic component having a first electrode and a second electronic component having a second electrode; and The first electronic component and the second electronic component are thermally pressed together by the adhesive composition to electrically connect the first electrode and the second electrode to each other.

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

7. The method for manufacturing the connecting structure according to claim 6, wherein, The thickness of the surface layer is less than 3 μm.

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