TW201843276A - Adhesive composition and method for producing connected object - Google Patents

Abstract

An aspect of the present invention relates to an adhesive composition which comprises an adhesive component and electroconductive particles, wherein the electroconductive particles each comprise a plastic particle and a metal layer covering the plastic particle and have a plurality of projections formed on the surface thereof, the plurality of projections having an average height of 85-1,200 nm.

Description

Adhesive composition and manufacturing method of linker

The present invention relates to a method for producing an adhesive composition and a linker.

In recent years, miniaturization, thinning, and high performance of electronic components have been advanced, and development of high-density mounting technology has been actively performed. In such high-density mounting, it is difficult to cope with the connection of electronic components and fine circuit electrodes by the conventional solder and rubber connectors. Therefore, a bonding method using an anisotropic conductive adhesive having excellent decomposition energy and a film thereof is often used. In the connection method, for example, when connecting a glass substrate of a liquid crystal display (Liquid Cristal Display) and a circuit member such as a flexible circuit board (FPC; Flexible Print Circuit), anisotropic conductivity including conductive particles is bonded. The film is sandwiched between the opposing electrodes, and is heated and pressurized to maintain the insulation between adjacent electrodes on the same substrate while electrically connecting the electrodes of the two substrates to each other, so that electrons having fine electrodes Parts and circuit components are then fixed.

In addition, according to the requirements for weight reduction and thinning of a module, it is desirable to use a flexible substrate such as a plastic substrate instead of the glass substrate. When connecting members using the substrate with an anisotropic conductive adhesive film, in order to reduce connection resistance, it has been studied to form protrusions on the surfaces of conductive particles contained in the anisotropic conductive adhesive film. The shape of the conductive particles was also evaluated (see Patent Document 1). [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2016-61722

[Problems to be Solved by the Invention] As an electrode of a flexible substrate or a glass substrate, for example, a transparent electrode made of a metal oxide or the like can be used. When FPC-like circuit members are connected to such circuit members having electrodes such as metal oxides, it tends to be difficult to ensure sufficient electrical connection. In particular, when the connection is performed using an adhesive containing conductive particles, there is room for improvement in the reliability of the electrical connection between the electrodes.

Therefore, the main object of the present invention is to obtain a more reliable electrical connection when a circuit member having a flexible substrate or a glass substrate is connected by an adhesive containing conductive particles. [Means for solving problems]

One aspect of the present invention is an adhesive composition containing an adhesive component and conductive particles. The conductive particles have plastic particles and a metal layer covering the plastic particles. A plurality of protrusions are formed on the surface of the conductive particles. The average height of the plurality of protrusions is 85 nm to 1200 nm.

Another aspect of the present invention is a method for manufacturing a connection body, which includes the steps of disposing a circuit connection material between a first circuit member and a second circuit member to produce a laminated body, the first circuit member having a first substrate And a first connection terminal provided on the first substrate, the second circuit member is disposed opposite to the first circuit member, and has a second substrate and a second connection terminal provided on the second substrate; The laminated body is heated and pressurized to electrically connect the first circuit member and the second circuit member to each other. The circuit connection material contains an adhesive component and conductive particles. The conductive particles have plastic particles and cover the plastic particles. In the metal layer, a plurality of protrusions are formed on the surface of the conductive particles, and the height of the plurality of protrusions is 85 nm to 1200 nm on average.

In each of the side surfaces, in the projection image of the conductive particles, the ratio of the area of the protrusions to the area of the surface of the conductive particles may be 8% to 60%. The conductive particle may have a layer made of Pd as a metal layer on the outermost surface of the conductive particle. The thickness of the layer formed of Pd may be 2 nm to 200 nm.

The adhesive composition can be used to electrically connect a first circuit component and a second circuit component to each other. The first circuit component has a first substrate and a first connection terminal provided on the first substrate. The second circuit member has a second substrate and a second connection terminal provided on the second substrate. In this case, the first substrate is an integrated circuit (IC) wafer or a flexible substrate, and the second substrate may be selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and A flexible substrate of at least one thermoplastic resin in the group consisting of polyethylene naphthalate. The first substrate is an IC wafer or a flexible substrate, and the second substrate may be a glass substrate or a composite substrate having a glass substrate and an insulating film provided on the glass substrate.

In the method for manufacturing the connector, the first substrate is an IC wafer or a flexible substrate, and the second substrate may be selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polynaphthalene. A flexible substrate of at least one thermoplastic resin in the group consisting of ethylene formate. The first substrate is an IC wafer or a flexible substrate, and the second substrate may be a glass substrate or a composite substrate having a glass substrate and an insulating film provided on the glass substrate. [Effect of the invention]

According to the present invention, when a circuit member having a flexible substrate or a glass substrate is connected with an adhesive containing conductive particles, a more reliable electrical connection can be obtained.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

The adhesive composition of one embodiment is an adhesive film formed into a film. In another embodiment, the adhesive composition may be in a state other than a film (for example, a paste).

FIG. 1 is a cross-sectional view schematically showing a film-shaped adhesive composition (adhesive film) according to an embodiment. As shown in FIG. 1, the adhesive film 1 in one embodiment includes an adhesive component (insulating adhesive) 2 and conductive particles 3 dispersed in the adhesive component 2. The thickness of the adhesive film 1 may be, for example, 10 μm to 50 μm.

The adhesive agent component in one embodiment contains a hardening component having insulation properties and hardened by heat or light. The adhesive component is defined as a solid component other than the conductive particles in the adhesive composition.

The curable component may include a radical polymerizable substance and a free radical generator, or may include a thermosetting resin, and may further include a radical polymerizable substance, a free radical generator, and a thermosetting resin.

The radical polymerizable substance is a substance having a functional group that is polymerized by a radical, and examples thereof include an acrylate, a methacrylate, and a maleimide compound. The content of the radical polymerizable substance may be, for example, 50% by mass to 80% by mass based on the total amount of the adhesive component.

Examples of the acrylate and methacrylate include urethane acrylate, urethane methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, and ethyl methacrylate. Diethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dimethylol tricyclodecane diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylic acid Ester, 2-hydroxy-1,3-dipropenyloxypropane, 2,2-bis [4- (propenyloxymethoxy) phenyl] propane, 2,2-bis [4- (acrylic acid) Oxypolyethoxy) phenyl] propane, dicyclopentenyl acrylate, tricyclodecyl acrylate, bis (acryloxyethyl) isocyanurate, ε-caproyl isocyanurate Ester modified tris (propylene ethoxyethyl) ester and tris (propylene ethoxyethyl) isocyanurate. These radically polymerizable substances can be used alone or in combination of two or more. From the viewpoint of adhesiveness, the radical polymerizable substance is preferably a urethane acrylate or a urethane methacrylate.

As a radically polymerizable substance, it is particularly preferable to use a urethane acrylate or a urethane methacrylate in combination from the viewpoint of improving the heat resistance, and to display it separately by crosslinking with an organic peroxide. A radically polymerizable substance having a Tg of 100 ° C or higher is produced. The radical polymerizable substance may have a dicyclopentenyl group, a tricyclodecyl group and / or a triazine ring, and preferably has a tricyclodecyl group or a triazine ring.

The radically polymerizable substance may also be at least one radically polymerizable substance having a viscosity of 100,000 mPa · s to 1000000 mPa · s at 25 ° C, and preferably one having a viscosity of 100,000 mPa · s to 500,000 mPa · s At least one kind of radical polymerizable substance. The viscosity of the radically polymerizable substance can be measured using a commercially available E-type viscometer.

The free radical generator is a compound that is decomposed by heating or light to generate a free radical, and is, for example, a peroxy compound or an azo-based compound. The free radical generator can be appropriately selected depending on the target connection temperature, connection time, pot life, and the like. The free radical generator may be, for example, one selected from the group consisting of benzamidine peroxide, difluorenyl peroxide, dicarbonate, peroxyester, ketal peroxide, dialkyl peroxide, and hydrogen peroxide. the above. From the viewpoint of high reactivity and pot life, the free radical generator is preferably an organic peroxide having a 10-hour half-life temperature of 40 ° C or higher and a 1-minute half-life temperature of 180 ° C or lower. The free radical generator may be used in combination with a decomposition accelerator, an inhibitor, or the like. The content of the free radical generator may be, for example, 0.05 to 15% by mass based on the total amount of the adhesive component.

When the adhesive component contains a radical-curable material, a polymerization inhibitor may be further included. The polymerization inhibitor may be hydroquinone, methyl ether hydroquinone, or the like. The content of the polymerization inhibitor may be 0.05 to 5% by mass based on the total amount of the adhesive component.

Examples of the thermosetting resin include epoxy resin, cyanate resin, maleimide resin, allyl nadic acid resin, phenol resin, urea resin, melamine resin, alkyd resin, acrylic resin, Unsaturated polyester resin, diallyl phthalate resin, silicone resin, resorcinol formaldehyde resin, xylene resin, furan resin, polyurethane resin, ketone resin, cyanuric acid Allyl resin, polyisocyanate resin, resin containing tris (2-hydroxyethyl) isocyanurate, resin containing triallyl trimellitate, and thermosetting property synthesized from cyclopentadiene Resin, thermosetting resin obtained by trimerization of aromatic dicyandiamide, and the like. Regarding the thermosetting resin, these may be used alone or in combination of two or more. The content of the thermosetting resin may be, for example, 20% by mass to 50% by mass based on the total amount of the adhesive component.

When the adhesive component contains a thermosetting resin, the adhesive component may further contain a curing agent. The hardener can be melamine and its derivatives, a hydrazine-based hardener, a boron trifluoride-amine complex, a phosphonium salt, an amine imine, a diamine maleimide, a polyamine salt, and a dicyandiamide. Modified products such as amines (dicyandiamide) can be used alone or in combination of two or more. In addition, the curing agent may be an addition polymerization type curing agent such as polyamines, polythiols, polyphenols, and acid anhydrides, or an addition polymerization type curing agent and a catalyst type curing agent may be used in combination. The content of the hardener may be 0.5% to 15% by mass based on the total amount of the adhesive component.

Microcapsules coated with these hardeners by using polymer materials such as polyurethane and polyester, metal films such as Ni and Cu, and inorganic materials such as calcium silicate to extend the life of the microcapsules are preferred.

The adhesive component may further contain fillers such as silicone particles, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents, and the like.

When the adhesive composition is formed into a film, the adhesive component may contain a resin having a functional group such as a hydroxyl group in order to improve the film forming property. The resin may also be polystyrene, polyethylene, polyvinyl butyraldehyde, polyvinyl formaldehyde, polyimide, polyamidine, polyester, polyvinyl chloride, polyphenylene ether, urea resin, melamine resin, phenol Resin, xylene resin, epoxy resin, polyisocyanate resin, phenoxy resin, polyimide resin, polyester urethane resin, polyurethane resin, etc., to further improve connection reliability From a viewpoint, a high molecular weight epoxy resin or a phenoxy resin having a weight-average molecular weight of 10,000 or more obtained by high performance liquid chromatography (HPLC) may be used. The adhesive component may also contain those resins modified by radical polymerizable functional groups. In order to adjust the melt viscosity and the like, a mixture of these resins with a styrene resin or an acrylic resin may also be contained. In another embodiment, in order to improve the film forming property, the adhesive component may contain rubber.

FIGS. 2 (a) and 2 (b) are cross-sectional views schematically showing one embodiment of the conductive particles 3 included in the adhesive film 1. As shown in FIG. 2 (a), in one embodiment, the conductive particles 3A include plastic particles 31 and a metal layer 32A covering the plastic particles 31.

It is preferable that substantially the entire surface of the plastic particles 31 is covered with the metal layer 32A, but the surface of the plastic particles 31 can also be made within a range that maintains a function as a circuit connection material (a function of electrically connecting circuit members to each other). A part is exposed without being covered with the metal layer 32A.

The plastic particles 31 may be, for example, particles containing a polymer containing at least one monomer selected from styrene and divinylbenzene as a monomer unit. The polymer may further include a (meth) acrylate as a monomer unit.

The diameter of the plastic particles 31 is preferably 1 μm or more and 40 μm or less on average. From the viewpoint of high-density mounting, the diameter of the plastic particles 31 is more preferably 1 μm or more and 30 μm or less on average. From the viewpoint of maintaining the connection state more stably when the surface of the electrode has unevenness, the diameter of the plastic particles 31 is more preferably 2 μm or more and 20 μm or less on average.

The metal layer 32A includes, for example, a metal layer. The metal layer 32A is formed of, for example, Ni, Cu, NiB, Ag, or Ru. The thickness of the metal layer 32A may be, for example, 50 nm or more and 300 nm or less. The thickness of the metal layer 32A refers to the thickness of a portion of the metal layer where the protrusions described later are not formed. The thickness of the metal layer 32A can be measured by an electron microscope.

As shown in FIG. 2 (b), in the conductive particle 3B according to another embodiment, the metal layer 32B may be a metal layer including two layers, a first metal layer 32a and a second metal layer 32b. That is, the conductive particle 3B according to another embodiment includes plastic particles 31, a first metal layer 32a covering the plastic particles 31, and a second metal layer 32b covering the first metal layer 32a.

The first metal layer 32a is formed of, for example, Ni. The second metal layer 32b may be formed of, for example, Au or Pd. From the viewpoint of further improving reliability, it is preferably formed of Pd. That is, the conductive particles 3B may have a layer made of Au or Pd as a metal layer on the outermost surface of the conductive particles 3B. From the viewpoint of further improving reliability, it is preferable to have a layer made of Pd.

The thickness of the first metal layer 32a may be, for example, 50 nm or more and 300 nm or less. The thickness of the second metal layer 32b may be, for example, 2 nm or more, 5 nm or more, or 10 nm or more, 200 nm or less, 100 nm or 50 nm or less, 2 nm to 200 nm, 2 nm to 100 nm, 2 nm to 50 nm, 5 nm to 200 nm, 5 nm to 100 nm, 5 nm to 50 nm, 10 nm to 200 nm, 10 nm to 100 nm, or 10 nm to 50 nm. The thicknesses of the first metal layer 32a and the second metal layer 32b refer to the thicknesses of the portions of the metal layer where the protrusions described later are not formed, respectively. The thicknesses of the first metal layer 32a and the second metal layer 32b can be measured by an electron microscope.

A plurality of protrusions 33 are formed on the surface of the conductive particles 3. In the conductive particle 3A shown in FIG. 2 (a), the protruding portion 33A is composed of a metal layer 32A including one layer. In the conductive particle 3B shown in FIG. 2 (b), the protruding portion 33B is composed of a metal layer 32B including two layers of a first metal layer 32a and a second metal layer 32b.

From the viewpoint of improving the reliability of the electrical connection, the height of the protrusion 33 is 85 nm or more, 90 nm or more, and 100 nm or more, and is 1200 nm or less, 1000 nm or less, 600 nm or less, 500 nm or less, 400 Below nm, below 300 nm, or below 200 nm. From the same viewpoint, the height of the protruding portion 33 may be 85 nm to 1200 nm, 85 nm to 1000 nm, 85 nm to 600 nm, 85 nm to 500 nm, 85 nm to 400 nm, or 85 nm to 300 nm. , 85 nm to 200 nm, 90 nm to 1200 nm, 90 nm to 1000 nm, 90 nm to 600 nm, 90 nm to 500 nm, 90 nm to 400 nm, 90 nm to 300 nm, 90 nm to 200 nm, 100 nm ～ 1200 nm, 100 nm ～ 1000 nm, 100 nm ～ 600 nm, 100 nm ～ 500 nm, 100 nm ～ 400 nm, 100 nm ～ 300 nm or 100 nm ～ 200 nm.

Here, the height of the protrusion 33 is determined by analyzing a two-dimensional image of a projected image including conductive particles. The analysis of the two-dimensional image can be performed in accordance with the method described in Japanese Patent Laid-Open No. 2016-61722.

Specifically, for example, it may be determined by a method including detecting a boundary between a projection image of each conductive particle in a two-dimensional image in which a plurality of conductive particles are captured and other regions, that is, a particle edge. Step of calculating the center coordinates of conductive particles on a two-dimensional image based on particle edges; dividing a particle edge into a plurality of particle edge portions (for example, 12) using a predetermined angle around the center coordinates as a unit Step), calculating the difference between the maximum value and the minimum value of the distance between the center coordinate and the particle edge according to a plurality of particle edge portions, and calculating the average value of these differences as the height of the protrusion; and calculating the conductivity for multiple A step of calculating the average value of the height of the protrusions (for example, an arbitrary number of 5 to 100).

In the analysis of the two-dimensional image, the edge of the particle substantially corresponds to the outer periphery of the two-dimensional projection image of the conductive particle including the unevenness derived from the protrusion. The degree distribution of the brightness obtained from the two-dimensional image usually indicates the minimum value of the portion reflecting the edge of the particle. The brightness corresponding to the minimum value is used as a first threshold value and the two-dimensional image is binarized to generate a binarized image. An edge formed in the obtained binarized image is detected as a particle edge. The center coordinates of the conductive particles on the two-dimensional image are calculated based on the particle edges. A circle that fits the edges of the particles is obtained by the least square method, and the center of the circle is the center coordinates of the conductive particles.

From the viewpoint of further improving the reliability of the electrical connection, it is preferable that the area ratio of the projection 33 to the entire projected image of the surface of the conductive particle 3 (area ratio of the projection 33) is 8% or more and 9% Above or above 20%, preferably below 60% or below 50%, preferably between 8% to 60%, 8% to 50%, 9% to 60%, 9% to 50%, 20% to 60% or 20% to 50%.

The area ratio of the protrusions can also be determined by analyzing a two-dimensional image of the conductive particles according to the method described in Japanese Patent Laid-Open No. 2016-61722. The area ratio of the protrusion can be determined, for example, by a method including the step of calculating a second threshold value corresponding to the boundary between the protrusion and a portion other than the protrusion from the degree distribution of brightness in a region inside the particle edge. ; A step of generating a binarized image by binarizing the area inside the edge of the particle by using the obtained second threshold; and calculating the area of the region corresponding to the protrusion in the obtained binarized image The ratio of the area to the inside of the particle edge is a step of the area ratio of the protrusion.

The conductive particles 3 having the protrusions can be obtained, for example, by forming a metal layer 32A and a metal layer 32B on the surface of the plastic particles 31 by metal plating. During metal plating, the thickness of the metal layer 32A and the metal layer 32B can be changed by changing the plating conditions to form the protruding portion 33. For example, in the metal plating process, the protruding portion 33 can be formed by gradually increasing the concentration of the plating solution.

Alternatively, even if the pH of the plating solution is adjusted, for example, the pH of the nickel plating solution is set to 6, a metal layer having raised protrusions can be formed (see "Surface Technology" by Mochizuki et al., Vol. No. 4, 429-432, 1997). In the case where glycine is used as a complexing agent that contributes to the stability of the plating bath, a metal layer having a flat surface can be formed, whereas in the case where tartaric acid or DL-malic acid is used as a complexing agent, Can form raised protrusions (for example, see "Amorphous Plating" by Ebara et al., Vol. 36, pages 35 to 37, 1994; "Electron of Circuit Installation Society" by Ebara et al., Vol. 10 No. 3, 148-152, 1995). By adopting these methods, the metal layer 32A and the metal layer 32B of the protruding portion 33 having a desired height and area ratio can be formed.

In the case of producing the conductive particles 3B shown in FIG. 2 (b), for example, after the first metal layer 32a having the protrusions is formed by the method described above, a layer of Au or Pd is formed by displacement plating, whereby A second metal layer 32b is obtained.

The content of the conductive particles 3 contained in the adhesive film 1 can be determined according to the fineness of the connected electrodes and the like. The content of the conductive particles 3 may be, for example, 1 part by volume or more and 50 parts by volume or less based on 100 parts by volume of the adhesive component, and is preferably 30 parts by volume or less from the viewpoint of insulation and manufacturing cost.

The adhesive composition may be a multilayer film (multilayer adhesive film). The multilayer adhesive film may be, for example, a two-layer structure consisting of a layer containing conductive particles and a layer containing no conductive particles, or may be a layer containing conductive particles and non-conductive particles provided on both sides thereof. Of three layers. The multilayer adhesive film may include a plurality of layers containing conductive particles. The multilayer adhesive film may be provided with an adhesive layer that exhibits high adhesiveness to the connected circuit members in consideration of the adhesiveness to the circuit members. When these multilayer adhesive films are used, conductive particles can be efficiently captured on the connection electrodes, and therefore, it is advantageous for connection of narrow-pitch circuit components.

The adhesive composition (adhesive film) described above is preferably used as a material (circuit connecting material) for connecting circuit members to each other, and is particularly preferably used as an anisotropic conductive adhesive for connecting circuit members to each other. Composition (anisotropic conductive adhesive film).

Next, a method for manufacturing a connected body using the adhesive film 1 will be described. 3 (a) and 3 (b) are cross-sectional views schematically showing a method for manufacturing a connected body according to an embodiment. First, as shown in FIG. 3 (a), a first circuit member 4, a second circuit member 5, and an adhesive film 1 (circuit connection material) are prepared. The first circuit member 4 includes a first substrate 6 and a first connection terminal 7 provided on one surface 6 a of the first substrate 6. The second circuit member 5 includes a second substrate 8 and a second connection terminal 9 provided on one surface 8 a of the second substrate 8.

Next, the first circuit member 4 and the second circuit member 5 are disposed so that the first connection terminal 7 and the second connection terminal 9 face each other, and the adhesive film 1 is disposed between the first circuit member 4 and the second circuit member 5. And make a laminated body.

Moreover, in FIG.3 (a), the whole laminated body is pressurized in the direction shown by an arrow, and the adhesive film 1 is hardened. The pressure at the time of pressing is, for example, 1 MPa to 10 MPa per unit of the total connection area. The method of hardening the adhesive film 1 may be a method using heating, or a method of irradiating with light in addition to heating. Heating can be performed, for example, at 100 ° C to 170 ° C. Pressing and heating (light irradiation as necessary) can be performed, for example, for 1 second to 160 seconds. Thereby, the first circuit member 4 and the second circuit member 5 are pressure-bonded via the hardened material of the adhesive composition constituting the adhesive film 1.

In this embodiment, the adhesive film 1 is arranged between the first circuit member 4 and the second circuit member 5. However, as another embodiment, instead of the adhesive film, a paste-like adhesive composition may be applied to On the first circuit member 4 or the second circuit member 5 or both.

As shown in FIG. 3 (b), the connecting body 10 according to an embodiment obtained in the manner includes: a first circuit member 4 having a first substrate 6 and a first connection terminal 7 provided on the first substrate 6; Two circuit members 5 having a second substrate 8 and a second connection terminal 9 provided on the second substrate 8; and a connection portion 11 provided between the first circuit member 4 and the second circuit member 5 to connect the first circuit The component 4 (first connection terminal 7) and the second circuit component 5 (second connection terminal 9) are electrically connected to each other. The connection portion 11 is composed of a cured product of the adhesive composition, and includes the cured product 12 of the adhesive component 2 and the conductive particles 3 dispersed in the cured product 12. In the connection body 10, the conductive particles 3 are interposed between the first connection terminal 7 and the second connection terminal 9, and the first connection terminal 7 and the second connection terminal 9 are electrically connected to each other.

The first substrate 6 may be, for example, an IC wafer or a flexible substrate. The second substrate 8 may be, for example, a flexible substrate, a glass substrate, or a composite substrate having a glass substrate and an insulating film provided on the glass substrate.

As a combination of the first substrate 6 and the second substrate 8, more specifically, the first substrate 6 may also be an IC wafer or a flexible substrate, and the second substrate 8 may also be a flexible substrate. Alternatively, the first substrate 6 may be an IC wafer or a flexible substrate, and the second substrate 8 may be a glass substrate or a composite substrate. In other words, when the second substrate 8 is a flexible substrate, the first substrate 6 may be an IC wafer or a flexible substrate. When the first substrate 6 is an IC wafer and the second substrate 8 is a flexible substrate, the adhesive film 1 may be used in order to connect a chip on plastic substrate (COP). When the first substrate 6 and the second substrate 8 are flexible substrates, the adhesive film 1 may be used in order to connect a film on plastic substrate (FOP).

The flexible substrate includes, for example, a material selected from the group consisting of polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene naphthalate ( Polyethylene naphthalate (PEN) is at least one thermoplastic resin in the group.

The flexible substrate may further include a modified film and / or a protective film formed on the surface of the organic substrate to improve optical and mechanical properties, such as hard coating. In order to facilitate handling and transportation of the flexible substrate, a reinforcing material selected from a glass substrate, stainless steel (SUS), or the like may be bonded to an organic substrate.

The thickness of the flexible substrate is preferably 10 μm or more and 200 μm or less or 125 μm or less in terms of ensuring the strength and ease of bending of the film formed on the substrate alone.

When a conventional circuit connection material is used, there is a case where an electrode on a flexible substrate is broken or easily cracked by heating and pressure applied to the circuit members by pressure bonding. In addition, regarding the connection of electrodes that are difficult to form a sufficient electrical connection, in order to suppress the damage of the electrodes, it is necessary to crimp the circuit members under conditions of lower temperature or lower stress. The circuit connection material (adhesive film) of this embodiment can have an advantageous effect compared with the conventional material in these aspects.

The glass substrate may be formed of soda glass, quartz glass, or the like. From the viewpoint of preventing damage due to external stress, the glass substrate may be a substrate that has been chemically strengthened. The composite substrate may also have a glass substrate and an insulating film made of polyimide or a colored organic material or inorganic material for decoration, which is provided on the surface of the glass substrate. In the composite substrate, electrodes may be formed on the substrate. Mentioned on the insulating film.

In the case where the second substrate 8 is a flexible substrate, the first substrate 6 may also be an electronic component such as a semiconductor wafer, a transistor, a diode, a gate body, and other passive components, a capacitor, a resistor, and a passive component such as a coil. Printed substrates, etc. When the first substrate 6 is an IC wafer, a tip of a bump or a gold wire formed by plating is melted with a welding gun or the like to form a gold ball. After the ball is crimped to the electrode pad, a A protruding electrode (a first connection terminal 7) such as a wire bump obtained by wire cutting can be used as the first circuit member 4.

Examples of the electrode material forming the first connection terminal 7 and the second connection terminal 9 include metals such as Ag paste, Ni, Al, Au, Cu, Ti, Mo, indium tin oxide (ITO), and indium oxide. Metal oxides such as zinc (Indium Zinc Oxide, IZO), electrical conductors such as silver nanowires, carbon nanotubes, etc. The first connection terminal 7 and the second connection terminal 9 may be formed of the same raw material or may be formed of different raw materials, but the same raw material is preferred. From the viewpoint of preventing disconnection, a surface layer made of an oxide, a nitride, an alloy, an organic substance, or the like may be further provided on the first connection terminal 7 and the second connection terminal 9. The first connection member 7 and the second connection member 9 may be provided one by one on the first circuit member 4 and the second circuit member 5, respectively. However, it is preferable to form a predetermined interval and to provide a plurality of them.

If the circuit connection material (adhesive film) is used, even if the first circuit member 4 is an FPC circuit board, and the second connection terminal 9 in the second circuit member 5 tends to be difficult to ensure sufficient electrical connection. When a metal oxide is formed, a more reliable electrical connection can also be obtained.

FIG. 4 is a cross-sectional view schematically showing a main part of a connecting body 10 according to an embodiment. It is considered that, as shown in FIG. 4, when the height of the protrusions 33 of the conductive particles 3 is within a predetermined range, when the circuit members are connected to each other, the electrical conduction existing between the first connection terminal 7 and the second connection terminal 9 is interposed. The sexual particles 3 can apply sufficient pressure to the first connection terminal 7 and the second connection terminal 9 (and the second substrate 8) through the protruding portion 33, so that a more reliable electrical connection can be obtained, for example, it is not easy to cause Increase in connection resistance at high temperature and humidity.

On the other hand, as shown in FIG. 5 (a cross-sectional view schematically showing a main part of a conventional connector), in the conventional connector 20, since the conductive particles 23 have lower protrusions 23a, they cannot be connected to the first The terminal 7 and the second connection terminal 9 (and the second substrate 8) apply sufficient pressure. Therefore, the previous connection body 20 is inferior in reliability of electrical connection. [Example]

Hereinafter, the present invention will be described in more detail with examples. However, the present invention is not limited to these examples.

(Production of conductive particles) (1) Plastic particles using tetramethylolmethane tetraacrylate, divinylbenzene, and styrene as monomers, and suspension polymerization using a polymerization initiator (benzidine peroxide) These are polymerized to obtain plastic particles.

(2-1) Conductive Particle 1-1 to Conductive Particle 1-3 The obtained plastic particles are subjected to electroless Ni plating to obtain a metal layer (Ni layer, thickness, etc.) having a protruding portion and formed of Ni. 0.2 μm) of conductive particles 1 to 3. During the Ni plating process, the thickness of the Ni layer is changed by appropriately adjusting the loading amount of the plating solution, the processing temperature, and the processing time to form protrusions having different heights and area ratios.

(2-2) Conductive particles 1-4 to 1-6 are formed on the Ni layers of each of the conductive particles 1 to 3 by replacement plating to form a layer made of Au having protrusions ( Au layer) to obtain conductive particles 4 to 6 respectively.

(2-3) Conductive particles 1-7 An Ni layer having a flat surface is formed on the obtained plastic particles, and an Au layer having a flat surface is further formed on the Ni layer to produce conductive particles.

(2-4) Conductive particle 2-1 to conductive particle 2-4 The obtained plastic particles were subjected to electroless Ni plating to obtain conductive particles having a Ni layer (thickness: 0.2 μm) containing protrusions. . During the Ni plating process, the plating thickness is changed by appropriately adjusting the loading amount of the plating solution, the processing temperature, and the processing time to form protrusions having different heights and area ratios. On the Ni layer of these conductive particles, a layer (Pd layer) made of Pd having protrusions was formed by replacement plating to obtain conductive particles 2-1 to 2-4, respectively.

(3) Height and area ratio of protrusions A two-dimensional image including each conductive particle was obtained with a scanning electron microscope. By analyzing the obtained two-dimensional block image by the method described in Japanese Patent Laid-Open No. 2016-61722, the heights and area ratios of the protrusions of 100 conductive particles were calculated, and these average value.

(Production of Adhesive Film (Circuit Connection Material)) 20 parts by mass of urethane acrylate (product name: UA-5500T, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) as a radical polymerizable substance 15 parts by mass of polybis (propylene ethoxyethyl) cyanate (product name: M-215, manufactured by Toa Synthesis Co., Ltd.), dimethylol tricyclodecane diacrylate (product name: DCP-A , Manufactured by Kyoeisha Chemical Kyoeisha Chemical Co., Ltd.) 5 parts by mass and 2-methacryloxyethyl ethyl phosphate (product name: P-2M, manufactured by Kyoeisha Chemical Kyoeisha Chemical Co., Ltd.) 1 8 parts by mass of benzamidine peroxide (product name: Nyper BMT-K, manufactured by Nippon Oil Co., Ltd.) and a polyester urethane resin (product name: UR4800, Toyo Textile Co., Ltd.) Co., Ltd.) 60 parts by mass of a solution having a concentration of 40% by mass was mixed and stirred to obtain a solution of an adhesive resin. The solution of the polyester urethane resin is prepared by dissolving the polyester urethane resin in a mixed solvent of toluene / methyl ethyl ketone = 50/50.

Each conductive particle was dispersed in the prepared binder resin solution at a ratio of 10 parts by volume relative to 100 parts by volume of the binder resin. Therefore, the silicone fine particles (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd.) having an average particle diameter of 2 μm were dispersed at a ratio of 20 parts by mass with respect to 100 parts by mass of the binder resin to obtain adhesion-containing Coating liquid for solvent resin, conductive particles and silicone fine particles. The coating solution was coated on a polyethylene terephthalate (PET) film (50 μm thick) having a surface treated on one side using a coating apparatus. The coating film was dried by hot air drying at 70 ° C. to produce an anisotropic conductive adhesive film (thickness: 18 μm) as a circuit connection material.

(Preparation of circuit members) Glass member A glass member having a glass substrate, and a Cu film (thickness: 30 nm) and an amorphous ITO connection terminal (thickness: 40 nm) laminated in this order on the glass substrate was prepared. · Flexible members: Flexible with polyethylene terephthalate (PET) film (elasticity coefficient at 25 ° C: 4600 MPa) and ITO connection terminals (thickness 20 nm) formed on the PET film Sex building block. Flexible Circuit Board (FPC) An FPC having a resin film substrate using polyethylene terephthalate (PET) as a substrate and wiring provided on the resin film substrate is prepared. The wiring of the FPC includes a Cu layer having a pitch of 0.3 mm (a space of 0.15 mm, an electrode width of 0.15 mm, and a height of 18 μm), a 3 μm-thick Ni plating layer, and a 0.03 μm Au plating. Connection terminal of the layer.

An anisotropic conductive adhesive film is sandwiched between the flexible member and the FPC. In this state, while heating the anisotropic conductive adhesive film so that the reaching temperature of the anisotropic conductive adhesive film becomes 160 ° C, the entire connection area is pressurized at a pressure of 2 MPa per unit for 10 seconds to obtain a connection. There is a flexible / FPC connection between a flexible member and an FPC. Similarly, the glass member and the FPC are connected by sandwiching an anisotropic conductive adhesive film therebetween, thereby obtaining a glass / FPC connector.

Each obtained connector was subjected to a reliability test at 85 ° C., 85% RH, and 72 hours. About the connection body before and after a test, the connection resistance between opposing circuit members was measured.

The characteristics and evaluation results of the obtained outermost surface layer, the height of the protrusions, and the ratio of the protrusion areas are shown in Tables 1 and 2.

[Table 1]

[Table 2]

1‧‧‧ Adhesive film

2‧‧‧ Adhesive ingredients

3, 3A, 3B, 23‧‧‧ conductive particles

4‧‧‧First Circuit Component

5‧‧‧Second circuit component

6‧‧‧First substrate

6a‧‧‧ side of the first substrate

7‧‧‧first connection terminal

8‧‧‧ second substrate

8a‧‧‧ side of the second substrate

9‧‧‧Second connection terminal

10, 20‧‧‧ connector

11‧‧‧ Connection Department

12‧‧‧hardened

31‧‧‧plastic particles

32A, 32B‧‧‧metal layer

32a‧‧‧first metal layer

32b‧‧‧Second metal layer

23a, 33, 33A, 33B ‧‧‧ protrusions

FIG. 1 is a cross-sectional view schematically showing an embodiment of an adhesive composition. 2 (a) and 2 (b) are cross-sectional views schematically showing an embodiment of conductive particles. 3 (a) and 3 (b) are cross-sectional views schematically showing an embodiment of a method for manufacturing a connected body. FIG. 4 is a cross-sectional view schematically showing a main part of a connection body according to an embodiment. FIG. 5 is a cross-sectional view schematically showing a main part of a conventional connection body.

Claims (12)

An adhesive composition includes an adhesive component and conductive particles. The conductive particles have plastic particles and a metal layer covering the plastic particles. A plurality of protrusions are formed on a surface of the conductive particles. The plurality of protrusions have an average height of 85 nm to 1200 nm. The adhesive composition according to item 1 of the scope of patent application, wherein in the projection image of the conductive particles, the ratio of the area of the protrusions to the area of the surface of the conductive particles is 8% to 60. %. The adhesive composition according to item 1 or item 2 of the patent application scope, wherein the conductive particles have a layer made of Pd on the outermost surface of the conductive particles as the metal layer. The adhesive composition according to item 3 of the scope of patent application, wherein the thickness of the layer formed of Pd is 2 nm to 200 nm. The adhesive composition according to any one of claims 1 to 4 of the scope of patent application, which is used to electrically connect a first circuit component and a second circuit component to each other, and the first circuit component has a first A substrate and a first connection terminal provided on the first substrate, the second circuit member having a second substrate and a second connection terminal provided on the second substrate, the first substrate being an integrated circuit A wafer or a flexible substrate, the second substrate comprising at least one selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate Flexible substrate made of thermoplastic resin. The adhesive composition according to any one of claims 1 to 4 of the scope of patent application, which is used to electrically connect a first circuit component and a second circuit component to each other, and the first circuit component has a first A substrate and a first connection terminal provided on the first substrate, the second circuit member having a second substrate and a second connection terminal provided on the second substrate, the first substrate being an integrated circuit A wafer or a flexible substrate, and the second substrate is a glass substrate or a composite substrate having a glass substrate and an insulating film provided on the glass substrate. A method for manufacturing a connection body includes the following steps: arranging a circuit connection material between a first circuit member and a second circuit member to produce a laminated body, the first circuit member having a first substrate and disposed on the first A first connection terminal on a substrate, the second circuit member and the first circuit member being arranged opposite to each other, and having a second substrate and a second connection terminal provided on the second substrate, The first circuit member and the second circuit member are electrically connected to each other by heating and pressing. The circuit connection material contains an adhesive component and conductive particles, and the conductive particles include plastic particles and a coating. In the metal layer of the plastic particle, a plurality of protrusions are formed on a surface of the conductive particle, and an average height of the plurality of protrusions is 85 nm to 1200 nm. The method for manufacturing a connected body according to item 7 of the scope of patent application, wherein in the projection image of the conductive particle, a ratio of an area of the protrusion to an area of the surface of the conductive particle is 8% to 60%. The method for manufacturing a connected body according to item 7 or item 8 of the scope of patent application, wherein the conductive particles have a layer made of Pd on the outermost surface of the conductive particles as the metal layer. The method for manufacturing a connector according to item 9 of the scope of patent application, wherein the thickness of the layer formed of Pd is 2 nm to 200 nm. The method for manufacturing a connector according to any one of claims 7 to 10 in the scope of the patent application, wherein the first substrate is an integrated circuit wafer or a flexible substrate, and the second substrate includes a substrate selected from A flexible substrate of at least one thermoplastic resin from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate. The method for manufacturing a connection body according to any one of claims 7 to 10 in the scope of patent application, wherein the first substrate is a integrated circuit wafer or a flexible substrate, and the second substrate is a glass substrate or A composite substrate having a glass substrate and an insulating film provided on the glass substrate.