Adhesive composition, connection structure, and method for producing connection structure

Abstract

The purpose of the present invention is to provide a binder composition capable of forming an anisotropic conductive film in which the connection resistance between electrodes is suppressed to a low level. The present invention is an adhesive composition in which the difference between the curing start temperature and the curing end temperature is 20 DEG C or less.

Description

Technical Field

[0001] This invention relates to an adhesive composition, a connecting structure, and a method for manufacturing the connecting structure. Background Technology

[0002] In the fields of semiconductors, liquid crystal displays, smartphones, personal computers, headphones, smartwatches, wearable devices, and other devices, anisotropic conductive films are used to fix electronic components and connect circuits. Anisotropic conductive films are formed, for example, by dispersing conductive particles in an adhesive film. For instance, Patent Document 1 discloses an anisotropic conductive film in which conductive particles are dispersed in an insulating adhesive composition containing a (meth)acrylate monomer composition, a free radical polymerization initiator, and a film-forming resin. The (meth)acrylate monomer composition contains (meth)acrylate monomers having cyclic ester residues or cyclic amide residues.

[0003] By sandwiching an anisotropic conductive film between opposing electronic components and performing thermoforming, the adhesive component in the anisotropic conductive film melts and flows, thereby trapping conductive particles between opposing electrodes, thus electrically connecting the opposing electrodes to each other. At this time, the molten and flowing adhesive component fills and solidifies between adjacent conductive particles and between adjacent electrodes within the same electronic component, thus enabling the electronic components to be bonded and fixed together while maintaining insulation between adjacent electrodes within the same electronic component.

[0004] Previous technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-242101 Summary of the Invention

[0007] The technical problem to be solved by the invention

[0008] In recent years, micro-OLED mounting devices for AR / VR applications have been developing towards higher functionality, miniaturization, and thinner designs. In these devices, components with low heat resistance, such as micro-OLEDs, are located near the mounting portion based on anisotropic conductive films, making it undesirable to perform hot-pressing at high temperatures during mounting. Therefore, there is a need for anisotropic conductive films that can be cured at low temperatures (e.g., below 130°C).

[0009] However, if anisotropic conductive films capable of low-temperature curing are used, the problem of adhesive residue forming between the electrodes and conductive particles becomes particularly pronounced. Specifically, if hot pressing is performed at low temperatures during installation, the adhesive component in the anisotropic conductive film cures in a state of insufficient flow, which may sometimes result in adhesive residue forming between the electrodes and conductive particles, thereby increasing the connection resistance between the electrodes.

[0010] Therefore, one aspect of the present invention is to provide an adhesive composition capable of forming an anisotropic conductive film that suppresses the connection resistance between electrodes.

[0011] means for solving technical problems

[0012] The curing end temperature of the adhesive composition can be appropriately selected based on the curing end method of the adhesive composition according to the hot-pressing temperature. Therefore, when hot-pressing at low temperatures, the curing end temperature is lower than that when hot-pressing at high temperatures, and consequently, the curing start temperature of the adhesive composition is also generally lower. On the other hand, in order to properly connect electronic components to each other, it is necessary to allow the adhesive components to flow during hot pressing. However, if the curing start temperature of the adhesive composition is lower, the temperature range in which the adhesive components can flow (the temperature range below the curing start temperature) becomes narrower. Therefore, the time for the adhesive components to flow is shorter, and the problem of insufficient flow becomes more pronounced during hot pressing at low temperatures. The inventors have conducted in-depth research and found that by reducing the difference between the curing start temperature and the curing end temperature of the adhesive composition, the temperature range in which the adhesive components can flow before the adhesive composition cures (temperature range lower than the curing start temperature) becomes relatively wider, which can ensure a longer time for the adhesive components to flow. As a result, it is less likely for adhesive component residue to be generated between the electrode and the conductive particles, thereby suppressing the connection resistance between the electrodes to be low.

[0013] The present invention provides, in several aspects, the following [1] to [8].

[0014] [1] An adhesive composition, wherein,

[0015] The difference between the curing start temperature and the curing end temperature is less than 20℃.

[0016] [2] According to the adhesive composition of [1], wherein,

[0017] The curing end temperature is below 130℃.

[0018] [3] The adhesive composition according to [1] or [2], wherein,

[0019] The curing start temperature is above 85℃.

[0020] [4] The adhesive composition according to any one of [1] to [3] comprises (meth)acrylate.

[0021] [5] The adhesive composition according to any one of [1] to [4] contains conductive particles.

[0022] [6] A connecting structure comprising:

[0023] A first electronic component, having a first electrode;

[0024] A second electronic component, having a second electrode; and

[0025] A connecting part 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.

[0026] The connecting portion comprises a cured product of the adhesive composition described in any one of [1] to [5].

[0027] [7] A method for manufacturing a connecting structure, comprising the following steps:

[0028] The adhesive composition described in any one of [1] to [5] is disposed between a first electronic component having a first electrode and a second electronic component having a second electrode; and

[0029] The first electronic component and the second electronic component are thermally pressed together by an adhesive composition, thereby electrically connecting the first electrode and the second electrode to each other.

[0030] [8] According to the manufacturing method described in [7], wherein,

[0031] Hot pressing should be performed below 130°C.

[0032] Invention Effects

[0033] According to one aspect of the present invention, it is possible to provide an adhesive composition capable of forming an anisotropic conductive film that suppresses the connection resistance between electrodes. Attached Figure Description

[0034] Figure 1 This is a schematic cross-sectional view showing one embodiment of the adhesive film.

[0035] Figure 2 This is a schematic cross-sectional view showing another embodiment of the adhesive film.

[0036] Figure 3 This is a schematic cross-sectional view showing one embodiment of the connecting structure.

[0037] Figure 4This is a schematic cross-sectional view illustrating one embodiment of a method for manufacturing a connecting structure. Detailed Implementation

[0038] Hereinafter, with appropriate reference to the accompanying drawings, the embodiments of the present invention will be described in detail.

[0039] <Adhesive Composition>

[0040] In one embodiment of the adhesive composition, the curing start temperature (T) on ) and curing end temperature (T) off The difference between the two is less than 20°C. The adhesive composition is a thermosetting adhesive composition that cures by heating. The T of the adhesive composition... on and T off These refer to the temperatures at which the curing and heating reaction of the adhesive composition begins and ends, respectively. The curing start temperature and curing end temperature are determined by DSC (Digital Subtraction Angiography) measurements of the adhesive composition under conditions of a heating rate of 10℃ / min and a measurement temperature range of 40℃~250℃. on It is the temperature at the intersection of the tangent line at the inflection point between the rise and the peak of the DSC curve corresponding to the curing reaction of the adhesive composition and the extrapolated baseline of the DSC curve. Furthermore, in this peak, T... off It is the temperature at the intersection of the tangent line at the inflection point between the peak and the descent point of the DSC curve and the extrapolated baseline of the DSC curve.

[0041] T of adhesive composition on With T off The difference (T) off -T on () can be below 18℃, below 16℃, below 15℃, or below 14℃. Furthermore, T off -T on Above 0℃, it can be above 1℃ or above 5℃.

[0042] From the viewpoint of promoting the flow of the adhesive composition before curing, the curing start temperature (T) on The temperature can be above 80℃, 85℃, or 87℃. Furthermore, T... on It can be below 120℃, below 110℃, below 105℃, below 103℃, or below 101℃.

[0043] From the perspective of improving the reaction rate of the adhesive composition during curing at low temperatures (hereinafter, also referred to as "reaction rate"), the curing end temperature (T) off () can be below 130℃, below 120℃, or below 110℃. Furthermore, T off It can be above 100℃ or above 105℃.

[0044] The adhesive composition may contain (meth)acrylate. 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 of phosphate.

[0045] The content of (meth)acrylate is based on the total mass of the solid components contained in the adhesive composition (when the adhesive composition contains conductive particles as described later, the solid components other than the conductive particles contained in the adhesive composition are also referred to as "adhesive components"), and can be 10% or more by mass, 20% or more by mass, 30% or more by mass, or 40% or more by mass, or less than 80% by mass, 70% or less by mass, 60% or less by mass, or 50% or less by mass.

[0046] The adhesive composition 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. Examples of other polymerizable substances include maleimide compounds.

[0047] The content of polymeric substances other than (meth)acrylate is based on the total mass of the adhesive components and can be less than 10% by mass, less than 5% by mass, or less than 1% by mass.

[0048] The adhesive composition may contain a curing agent (thermal free radical polymerization initiator). The curing agent is a compound that generates free radicals through thermal decomposition.

[0049] Examples of curing agents include peroxides and azo compounds. Examples of peroxides include diacyl peroxides such as dioctanoyl peroxide, dilauroyl peroxide, distearate 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.

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

[0051] As a curing agent, one of the aforementioned peroxides and azo compounds can be used alone, or in combination of two or more. By selecting the type of curing agent (or, when using two or more curing agents in combination, a combination of two or more curing agents), the Tt of the adhesive composition can be adjusted. on Preferably, the adhesive composition includes at least one of a diacyl peroxide and a peroxide ester as a curing agent. The 1-minute half-life temperature of the diacyl peroxide and the peroxide ester can be independently between 90 and 175°C. Furthermore, the molecular weight of the diacyl peroxide and the peroxide ester can be independently between 180 and 1000.

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

[0053] The adhesive composition may include a curing modifier. The curing modifier is a compound that rapidly reacts with initiating free radicals generated by the decomposition of the curing agent, or with growth free radicals generated by the attack of these initiating free radicals on the free radical polymerizable compound, and further generates free radicals upon heating above 60°C, thereby promoting the polymerization of the free radical polymerizable compound. By adding this curing modifier or adjusting its content, the curing temperature (T) can be adjusted accordingly. off and T on Therefore, it is possible to transfer T off -T on Adjustments can be made within the aforementioned range. Furthermore, the flowability of the adhesive composition can also be adjusted by adding a curing modifier or adjusting the content of the curing modifier.

[0054] Curing modifiers can be, for example, amine compounds having divalent organic groups represented by the following general formula (A).

[0055]

[0056] In general formula (A), X 1 X 2 X 3 and X 4 Each alkyl group can be independently represented by a hydrogen atom or a carbon atom number of 1 to 5. Here, alkyl groups include not only straight-chain alkyl groups, but also branched alkyl groups and cyclic alkyl groups.

[0057] Furthermore, an amine compound having a divalent organic group represented by general formula (A) can be an amine compound represented by the following general formula (1).

[0058]

[0059] In general formula (1), R 1 and R 2 Each of the following can independently represent a hydrogen atom, a hydroxyl group, or a monovalent organic group: X 1 X 2 X 3 and X 4 Each can be independently represented by an alkyl group having 1 to 5 hydrogen atoms or carbon atoms.

[0060] The aforementioned organic groups refer to substituents containing carbon. The structure of these substituents is not particularly limited. As a group that can be used as R... 2 The monovalent organic group can include alkyl, aryl, alkoxy, ether, and ester groups having 1 to 10 carbon atoms. Examples of alkyl groups with 1 to 10 carbon atoms include methyl. Examples of alkoxy groups with 2 to 20 carbon atoms include octyloxy. Furthermore, the above-mentioned ester groups can be formed by reacting monocarboxylic acids such as methacrylic acid and 2-methylhexanoic acid, dicarboxylic acids such as sebacic acid, and tetracarboxylic acids with R.2 It is obtained by esterification of compounds with hydroxyl groups.

[0061] In the above general formula (1), R 1 It can be a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an aryl group, an alkoxy group having 2 to 20 carbon atoms, or a monovalent organic group represented by the following general formula (2). For example, methyl can be listed as an alkyl group having 1 to 10 carbon atoms. For example, octyloxy can be listed as an alkoxy group having 2 to 20 carbon atoms.

[0062]

[0063] In general formula (2), R 3 R represents an alkyl group having 1 to 5 hydrogen atoms or carbon atoms. 4 R represents an ester group, benzyl ester group, carboxyl group, or aryl group with 1 to 5 carbon atoms. 5 The 'n' represents a hydrogen atom, an alkyl group with 1 to 20 carbon atoms, an alkoxy group with 1 to 20 carbon atoms, a phenoxy group, an aryl group, a carbonyloxy group with 1 to 20 carbon atoms, a phenylcarbonyloxy group, or a vinyl group, where 'n' represents an integer from 1 to 20. However, phenoxy, aryl, and phenylcarbonyloxy groups can be substituted with alkyl groups with 1 to 5 carbon atoms. Amine compounds can be used alone or in mixtures of two or more.

[0064] The curing modifier preferably has one or more aminooxy groups within its molecule. This curing modifier exists as a stable free radical even in air, thus offering the advantage of improving the shelf life stability of the adhesive composition.

[0065] Specifically, examples of compounds having the above-mentioned aminooxy group structure include 2,2,6,6-tetramethylpiperidine-1-oxy, 2,2-dimethyl-6-phenylpiperidine-1-oxy, 2,2,6-trimethyl-6-phenylpiperidine-1-oxy, 2,6-diphenylpiperidine-1-oxy, 4-acetamide-2,2,6,6-tetramethylpiperidine-1-oxy, and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxy. 4-Carboxy-2,2,6,6-Tetramethylpiperidine-1-oxy, 3-Carboxy-2,2,6,6-Tetramethylpiperidine-1-oxy, 4-(2-chloroacetamide)-2,2,6,6-Tetramethylpiperidine-1-oxy, 4-hydroxy-2,2,6,6-Tetramethylpiperidine-1-oxy, 4-hydroxy-2,2,6,6-Tetramethylpiperidine-1-oxybenzoate, 4-(2-iodoacetamide)-2,2,6,6 -Tetramethylpiperidine-1-oxy, 4-isothiocyanate-2,2,6,6-tetramethylpiperidine-1-oxy, 4-isocyanate-2,2,6,6-tetramethylpiperidine-1-oxy, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxy, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxy, 2,2-dimethyl-6-cyclohexylpiperidine-1-oxy, 2,6-dicyclohexylpiperidine-1- Oxygen groups, such as 2,2-dimethyl-6-cyclopentylpiperidine-1-oxy, 2,6-dicyclopentylpiperidine-1-oxy, 2,2,5-trimethyl-4-phenyl-3-azahexane-3-oxy, 2,2,5,5-tetramethylpyrrolidine-1-oxy, 2,5-diphenylpyrrolidine-1-oxy, 2,2-dimethyl-5-phenylpyrrolidine-1-oxy, and 2,2,5-trimethyl-5-phenylpyrrolidine-1-oxy, etc. Compounds with an aminooxy group can be used alone or in combination of two or more.

[0066] The content of the curing modifier is based on the total mass of the adhesive components and can be above 0.001% by mass, above 0.01% by mass, above 0.05% by mass, or above 0.07% by mass, or below 30% by mass, below 20% by mass, below 10% by mass, below 5% by mass, or below 1% by mass.

[0067] The adhesive composition 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.

[0068] The content of thermoplastic resin is based on the total mass of the adhesive components, and can be above 20% by mass or below 50% by mass.

[0069] The adhesive composition may also include other components such as adhesive-giving agents, coupling agents (silane coupling agents, etc.), ion trapping agents, visual recognition agents, dispersants, photoradical polymerization initiators, and fillers. The content of other components is based on the total mass of the adhesive components, and may be more than 1% by mass or less than 20% by mass.

[0070] The adhesive composition may contain conductive particles. The conductive particles may have a non-conductive core and a conductive layer disposed on the core. Preferably, the surface of the core is substantially entirely covered by the conductive layer, but a portion of the surface of the core may be exposed without being covered by the conductive layer, within the range necessary to maintain the function of electrically connecting electronic components to each other.

[0071] The core 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 can 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 diameter of the core can, for example, be an average of 1 μm or more, or 2 μm or more, or 40 μm or less, 30 μm or less, or 20 μm or less.

[0072] The conductive layer is formed, for example, of Ni, Cu, Ag, Ru, or Pd, or an alloy containing these metallic elements. The alloy can be, for example, a Ni-containing alloy (Ni alloy). Examples of Ni alloys include Ni-B, Ni-P, and Ni-WB. The thickness of the conductive layer can be, for example, 50 nm or more, or less than 300 nm. The thickness of the conductive layer can be measured using an electron microscope.

[0073] The conductive layer can consist of one, two, or three or more conductive layers. In the case where the conductive layer consists of two conductive layers, the conductive particle can have a first conductive layer disposed on its outermost surface and a second conductive layer disposed between the first conductive layer and the core. The first conductive layer is formed, for example, of Au or Pd. The second conductive layer is formed, for example, of Ni. The thickness of the first conductive layer can be, for example, 2 nm or more, or less than 200 nm. The thickness of the second conductive layer can be, for example, 50 nm or more, or less than 300 nm.

[0074] The conductive particles can be roughly spherical. Multiple protrusions can be formed on the surface of the conductive particles. These multiple protrusions can be composed of one conductive layer or two conductive layers.

[0075] The average particle size of the conductive particles can be, for example, greater than 1 μm or less than 40 μm. The average particle size of the conductive particles is determined as follows: by observing with SEM, the particle size of 10 conductive particles is measured, and the average value of the 10 data points is calculated.

[0076] The content of conductive particles is based on the total mass of the solid components in the adhesive composition, and can be more than 5% by mass, more than 10% by mass, less than 30% by mass, or less than 25% by mass.

[0077] The content of conductive particles is based on the total volume of the solid components in the adhesive composition, and can be more than 0.1% by volume, less than 50% by volume, or less than 40% by volume.

[0078] 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 single layer formed by an adhesive component (insulating adhesive) 2 and conductive particles 3 dispersed in the adhesive component 2.

[0079] 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.

[0080] For example, such as Figure 2 As 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.

[0081] 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".

[0082] When the adhesive composition is in film form, the T of the adhesive composition (adhesive film) on and T off The value is determined by performing DSC (Digital Subtraction Angiography) measurements on the entire adhesive film. In cases where the adhesive film has two or more regions, the value (T) is determined by performing DSC measurements on the entire adhesive film with each of the two or more regions. on and T off For example, in finding Figure 2 The adhesive film 1 shown has a T on and T off In this case, the laminate of the first adhesive layer 1A and the second adhesive layer 1B is used as the test object, and DSC is performed by the above method.

[0083] 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.

[0084] 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.

[0085] <Connection Structure>

[0086] One embodiment of the connection structure includes the following: 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, 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 above.

[0087] Figure 3 This is a schematic cross-sectional view illustrating one embodiment of the connecting structure. For example... Figure 3 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 the first electronic component 4 and the second electronic component 5.

[0088] 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.

[0089] There are no particular restrictions on whether the first electronic component 4 and the second electronic component 5 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, such as micro OLEDs; passive components such as capacitors, resistors, and coils; and substrates with electrodes such as printed circuit boards.

[0090] 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).

[0091] Examples of electrode materials used to form 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.

[0092] 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.

[0093] The connecting portion 6 contains an insulating material 7, which is a cured product of the adhesive composition, and conductive particles 3. The conductive particles 3 can be 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.

[0094] 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 sufficiently reduced. Thus, the current flow between the first electrode 42 and the second electrode 52 can be smooth, thereby fully utilizing the functions of the first electronic component 4 and the second electronic component 5.

[0095] <Manufacturing Method of Connecting Structures>

[0096] The aforementioned connection structure can be manufactured by a method comprising the following steps: disposing the 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.

[0097] Figure 4 This is a schematic cross-sectional view illustrating one embodiment of a manufacturing method for a connecting structure. For example... Figure 4 As 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. When the adhesive film 1 is... Figure 2 In the case of having a first adhesive layer 1A and a second adhesive layer 1B as shown, 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 contact the main surface 41a of the first electronic component 4.

[0098] 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.

[0099] Next, as Figure 4 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 disposed 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.

[0100] 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 4 (b) Heating and pressurizing are performed in the direction of arrow A. By heating and pressurizing in the direction of arrow A, the adhesive film 1 is cured, thereby electrically connecting the first electrode 42 and the second electrode 52. As a result, the following is obtained: Figure 3 The connection structure 10 shown.

[0101] Hot pressing can be performed, for example, at a pressure of 5 MPa or more per total joint area, or at a pressure of 20 MPa or less. Furthermore, hot pressing can be performed at a pressure greater than that of the adhesive composition (adhesive film). onThe process is performed at high temperatures. Hot pressing can be performed, for example, above 100°C, or below 170°C, 150°C, or 130°C. The pressing and heating times during hot pressing can be, for example, more than 10 seconds or less than 60 seconds.

[0102] In the connection structure 10 obtained as described above, the conductive particle 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.

[0103] By heating and pressurizing the adhesive film 1, the adhesive component 2 can be cured to form an insulating material 7 while significantly reducing the distance between the first electrode 42 and the second electrode 52. Thus, the first electronic component 4 and the second electronic component 5 are securely connected via the connecting part 6.

[0104] Example

[0105] The present invention will now be described in more detail with reference to embodiments. The present invention is not limited to these embodiments.

[0106] <Synthesis of Polyurethane Acrylate (UA1)>

[0107] 2500 parts by weight (2.50 mol) of poly(1,6-hexanediol carbonate) (trade 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, nitrogen was thoroughly introduced into the reaction vessel, and the 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.

[0108] (Measurement conditions)

[0109] Device: Manufactured by Tosoh Corporation, GPC-8020

[0110] Detector: Manufactured by TOSOH CORPORATION RI-8020

[0111] Chromatographic column: Manufactured by Hitachi Chemical Company, Ltd. Gelpack GLA160S + GLA150S

[0112] Sample concentration: 120 mg / 3 mL

[0113] Solvent: Tetrahydrofuran

[0114] Injection volume: 60μL

[0115] Pressure: 2.94 × 10 6 Pa (30kgf / cm) 2 )

[0116] Flow rate: 1.00 mL / min

[0117] <Comparative Example 1>

[0118] (Preparation of the first adhesive composition)

[0119] The following mixtures were combined to obtain a first adhesive composition: 17 parts by weight of dimethyloltricyclodecane diacrylate (product name: DCP-A, manufactured by KYOEISHA CHEMICAL Co., Ltd.) as a polymerizable substance, 30 parts by weight of polyurethane acrylate (UA1) prepared 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, 2.5 parts by weight of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (product name: PERHEXA 25O, manufactured by NOF CORPORATION) as a curing agent, 45 parts by weight of polyester urethane resin (product name: UR-8200, manufactured by TOYOBO CO.,LTD.) as a thermoplastic resin, and 3-glycidoxypropyltrimethoxysilane (product name: SH-6040, manufactured by Dow Toray) as a silane coupling agent. 2.8 parts by weight of AEROSIL (product name: R-202, manufactured by NIPPON AEROSIL CO.,LTD.) as filler material; 2.5 parts by weight of conductive particles (average particle size: 3μm) having a non-conductive core and a conductive layer disposed on the core and having multiple protrusions formed on the surface.

[0120] (Preparation of the second adhesive composition)

[0121] The following mixtures were used to obtain a second adhesive composition: 30 parts by weight of dimethyloltricyclodecane diacrylate (product name: DCP-A, manufactured by KYOEISHA CHEMICAL Co., Ltd.) as a polymerizable substance; 27.5 parts by weight of polyurethane acrylate (UA1) prepared as described above; 2.5 parts by weight of ethylene oxide modified dimethacrylate phosphate (product name: PM-21, manufactured by Nippon Kayaku Co., Ltd.) as a curing agent; 5.0 parts by weight of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (product name: PERHEXA25O, manufactured by NOF CORPORATION.) as a thermoplastic resin; 27.5 parts by weight of polyester urethane resin (product name: UR-4800, manufactured by TOYOBO CO.,LTD.) and phenoxy resin (product name: YP-70, manufactured by NIPPON STEEL Chemical & Material Co., Ltd.) as a thermoplastic resin. 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 material, and 8 parts by weight of AEROSIL (product name: R-202, manufactured by NIPPON AEROSIL CO.,LTD.) as a filler material.

[0122] 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).

[0123] <Example 1>

[0124] In the second adhesive composition, the amount of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane as a curing agent was changed to 4.8 parts by mass, and 0.5 parts by mass of dilauryl peroxide (product name: PERLOYL L, manufactured by NOF CORPORATION) as a curing agent and 0.1 parts by mass of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy (manufactured by Tokyo Chemical Industry Co., Ltd.) as a curing modifier were further added. Otherwise, an adhesive film was prepared in the same manner as in Comparative Example 1. The content of conductive particles, based on the total volume of the adhesive film, was 1 volume.

[0125] <Example 2>

[0126] In the second adhesive composition, the amount of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane as a curing agent was changed to 4.5 parts by mass, and the amount of dilauryl peroxide was changed to 1.0 part by mass. Otherwise, the adhesive film was prepared in the same manner as in Example 1. The content of conductive particles, based on the total volume of the adhesive film, was 1 volume.

[0127] <Example 3>

[0128] In the second adhesive composition, the amount of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane as a curing agent was changed to 4.0 parts by mass, and the amount of dilauryl peroxide was changed to 2.0 parts by mass. Otherwise, the adhesive film was prepared in the same manner as in Example 1. The content of conductive particles, based on the total volume of the adhesive film, was 1 volume.

[0129] <Example 4>

[0130] In the second adhesive composition, the amount of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane as a curing agent was changed to 3.5 parts by mass, and the amount of dilauryl peroxide was changed to 3.0 parts by mass. Otherwise, the adhesive film was prepared in the same manner as in Example 1. The content of conductive particles, based on the total volume of the adhesive film, was 1 volume.

[0131] <Example 5>

[0132] In the second adhesive composition, the amount of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane as a curing agent was changed to 3.0 parts by mass, and the amount of dilauryl peroxide was changed to 4.0 parts by mass. Otherwise, the adhesive film was prepared in the same manner as in Example 1. The content of conductive particles, based on the total volume of the adhesive film, was 1 volume.

[0133] <Example 6>

[0134] In the second adhesive composition, the amount of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane as a curing agent was changed to 2.5 parts by mass, and the amount of dilauryl peroxide was changed to 5.0 parts by mass. Otherwise, the adhesive film was prepared in the same manner as in Example 1. The content of conductive particles, based on the total volume of the adhesive film, was 1 volume.

[0135] (The curing start temperature and curing end temperature of the adhesive film)

[0136] Under conditions of a heating rate of 10°C / min and a measurement temperature range of 40°C to 250°C, differential scanning calorimetry (DSC) was performed on each adhesive film (5 mg each) of Comparative Example 1 and Examples 1-6 under a nitrogen flow, using a DSC apparatus (product name: DSC7, manufactured by Perkin Elmer Co., Ltd.). The curing start temperature (T0) was determined based on the peak value of the curing reaction in the obtained DSC curves. on ) and curing end temperature (T) off Furthermore, the difference between the curing start temperature and the curing end temperature (T) was calculated. off -T on The results are shown in Table 1.

[0137] (Preparation of electronic components)

[0138] The following electronic components were prepared.

[0139] • Glass components

[0140] 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.

[0141] • Flexible printed circuit board (FPC)

[0142] An FPC (Flexible Printed Circuit) with a resin film substrate based on polyethylene terephthalate (PET) and wiring disposed on the resin film substrate was prepared. The wiring of the FPC has an electrode consisting of a Cu layer with a spacing of 70 μm (35 μm interval, 35 μm electrode width, and 18 μm thickness), a Ni layer with a thickness of 0.5 μm formed sequentially on the Cu layer, and an Au layer with a thickness of 2.5 μm.

[0143] (Construction of connecting structures)

[0144] An adhesive film of Comparative Example 1 was deposited on a glass component, and an FPC was 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) were positioned opposite each other. The first adhesive layer side of the adhesive film was in contact with the glass component. A silicone rubber cushioning material was placed on the surface of the FPC side of the laminate. Heating and pressurizing were performed from above the cushioning material using a hot-pressing device (heating method: pulse-heat type, manufactured by OHASHI ENGINEERING Co., Ltd.) to create the connection structure of Comparative Example 1, comprising the glass component, the cured adhesive film, and the FPC. The heating temperature was 120°C, the pressurization pressure was 14 MPa, and the heating and pressurization times were 30 seconds. The heating temperature refers to the set temperature of the hot-pressing device, and the pressurization pressure refers to the pressure applied to the total connection area. Furthermore, the connection structures of Examples 1 to 6 were fabricated using the adhesive films of Examples 1 to 6 in the same manner as described above.

[0145] (Resistance between electrodes)

[0146] For each connection structure in Comparative Example 1 and Examples 1-6, the connection resistance between electrodes (the electrodes of the glass component and the electrodes of the FPC) during low-temperature connection was investigated using a digital multimeter and the four-terminal method. The results are shown in Table 1.

[0147] (Reaction rate)

[0148] The connecting structures of Comparative Example 1 and Examples 1-6, prepared by the above method, were disassembled, and the cured adhesive film was scraped off to prepare 5 mg of evaluation samples of Comparative Example 1 and Examples 1-6, respectively. Next, the evaluation samples of Comparative Example 1 and Examples 1-6 were measured using a differential scanning calorimetry (DSC) apparatus (product name: DSC7, manufactured by PERKIN ELMER) under a nitrogen flow, at a measurement temperature range of 30°C to 250°C and a heating rate of 10°C / min, and the calorific value (J / g) of each evaluation sample was calculated. Furthermore, 5 mg of each adhesive film of Comparative Example 1 and Examples 1-6 was weighed out as control samples for each comparative example and example. For each control sample, DSC measurement was performed in the same manner as above, and the calorific value of the control sample was calculated. For each comparative example and example, the reaction rate was calculated using the following formula. The results are shown in Table 1.

[0149] Reaction rate (%) = {1 - (calorific value of evaluation sample / calorific value of control sample)} × 100

[0150] [Table 1]

[0151]

[0152] Symbol Explanation

[0153] 1-Adhesive film, 1A-First adhesive layer, 1B-Second adhesive layer, 2, 2A, 2B-Adhesive components, 3, 3A-Conductive particles, 4-First electronic component, 5-Second electronic component, 6-Connector, 7-Insulating material, 10-Connecting structure, 41-First substrate, 42-First electrode, 51-Second substrate, 52-Second electrode.

Claims

1. An adhesive composition, wherein, The difference between the curing start temperature and the curing end temperature is less than 20℃.

2. The adhesive composition according to claim 1, wherein, The curing end temperature is below 130°C.

3. The adhesive composition according to claim 1 or 2, wherein, The curing start temperature is above 85°C.

4. The adhesive composition according to claim 1 or 2, comprising (meth)acrylate.

5. The adhesive composition according to claim 1 or 2, wherein it comprises conductive particles.

6. 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 5.

7. A method for manufacturing a connecting structure, comprising the following steps: The adhesive composition of claim 5 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 bonded together by the adhesive composition, thereby electrically connecting the first electrode and the second electrode to each other.

8. The manufacturing method according to claim 7, wherein, The hot pressing is performed at a temperature below 130°C.

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