WO2018199329A1

WO2018199329A1 - Adhesive composition and method for producing connected object

Info

Publication number: WO2018199329A1
Application number: PCT/JP2018/017317
Authority: WO
Inventors: 研吾篠原; 泰典川端; 松田　和也; 光晴松沢; 由祐飯島
Original assignee: 日立化成株式会社
Priority date: 2017-04-28
Filing date: 2018-04-27
Publication date: 2018-11-01
Also published as: KR102573777B1; JPWO2018199329A1; CN110546222A; KR20200002953A; JP7287275B2; TW201843276A; CN114479712A

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 method for producing connector

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

In recent years, electronic components have become smaller, thinner, and higher in performance, and high-density packaging technology has been actively developed along with that. In such high-density mounting, it is difficult to handle the connection between the electronic component and the fine circuit electrode by using conventional solder and rubber connectors. Therefore, an anisotropic conductive adhesive excellent in resolution and a connection method using the film are frequently used. In this connection method, for example, when connecting a glass substrate of a liquid crystal display (Liquid Crystal Display) and a circuit member such as a flexible circuit board (FPC: Flexible Print Circuit), an anisotropic conductive material containing conductive particles is used. The electrode on both substrates is electrically connected to each other while maintaining the insulation between adjacent electrodes on the same substrate by sandwiching the adhesive adhesive film between the opposing electrodes, and heating and pressurizing. The electronic component having circuit board and the circuit member are bonded and fixed.

In addition, it is desired to use a flexible substrate such as a plastic substrate instead of the glass substrate because of the demand for lighter and thinner modules. When connecting members using such a substrate with an anisotropic conductive adhesive film, in order to reduce connection resistance, it is possible to form protrusions on the surface of the conductive particles contained in the anisotropic conductive adhesive film. The shape of such conductive particles has been evaluated (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-61722

As the electrode of the flexible substrate or the glass substrate, for example, a transparent electrode formed of a metal oxide or the like is used. When a circuit member such as an FPC is connected to a circuit member having an electrode such as a metal oxide, it tends to be difficult to ensure a sufficient electrical connection. In particular, when connecting using an adhesive containing conductive particles, there is room for improvement regarding 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 connecting a circuit member having a flexible substrate or a glass substrate with an adhesive containing conductive particles.

One aspect of the present invention includes an adhesive component and conductive particles, the conductive particles include plastic particles and a metal layer that covers the plastic particles, and a plurality of protrusions on the surface of the conductive particles. In the adhesive composition, the height of the plurality of protrusions is 85 to 1200 nm on average.

Another aspect of the present invention is a first circuit member having a first substrate and a first connection terminal provided on the first substrate, and is disposed to face the first circuit member. A circuit connection material is arranged between the second substrate and the second circuit member having the second connection terminal provided on the second substrate to produce a laminate, and the laminate is heated and heated. And the step of electrically connecting the first circuit member and the second circuit member to each other, the circuit connecting material contains an adhesive component and conductive particles, and the conductive particles are made of plastic. And a metal layer covering the plastic particles, and a plurality of protrusions are formed on the surface of the conductive particles, and the average height of the plurality of protrusions is 85 to 1200 nm. It is a manufacturing method.

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

The above-mentioned adhesive composition is provided on the first substrate and the first circuit member having the first connection terminal provided on the first substrate, the second substrate and the second substrate. The second circuit member having the formed second connection terminal may be used to electrically connect to each other. In this case, the first substrate is an IC chip or a flexible substrate, and the second substrate is a flexible substrate containing at least one thermoplastic resin selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate. It may be. The first substrate may be an IC chip 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 connection body manufacturing method, the first substrate is an IC chip or a flexible substrate, and the second substrate is at least one thermoplastic selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate. It may be a flexible substrate containing a resin. The first substrate may be an IC chip 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.

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

It is sectional drawing which shows typically one Embodiment of an adhesive composition. It is sectional drawing which shows typically one Embodiment of electroconductive particle. It is sectional drawing which shows typically one Embodiment of the manufacturing method of a connection body. It is sectional drawing which shows typically the principal part of the connection body of one Embodiment. It is sectional drawing which shows the principal part of the conventional connection body typically.

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

In one embodiment, the adhesive component has an insulating property and contains a curable component that is cured by heat or light. The adhesive component is defined as a solid content other than the conductive particles in the adhesive composition.

The curable component may contain a radical polymerizable substance and a free radical generator, may contain a thermosetting resin, and may contain 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 radicals, and examples thereof include acrylate, methacrylate, and maleimide compounds. The content of the radical polymerizable substance may be, for example, 50 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, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dimethylol tricyclodecane diacrylate, Trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-1,3-diaacryloxypropane, 2,2-bis [4- (acryloxymethoxy) phenyl] propane, 2,2-bis [4- (Acryloxypolyethoxy) phenyl] propane, dicyclopentenyl acrylate, tricyclodecanyl acrylate, bis Acryloxyethyl) isocyanurate, .epsilon.-caprolactone-modified tris (acryloyloxyethyl) isocyanurate, and tris (acryloyloxyethyl) isocyanurate. These radically polymerizable substances are used alone or in combination of two or more. The radically polymerizable substance is preferably urethane acrylate or urethane methacrylate from the viewpoint of adhesiveness.

As a radically polymerizable substance, from the viewpoint of improving heat resistance, a urethane acrylate or urethane methacrylate and a radically polymerizable substance having a Tg of 100 ° C. or more alone, cross-linked with an organic peroxide may be used in combination. Is particularly preferred. Such a radically polymerizable substance may have a dicyclopentenyl group, a tricyclodecanyl group and / or a triazine ring, and preferably has a tricyclodecanyl group or a triazine ring.

The radical polymerizable substance may be at least one radical polymerizable substance having a viscosity at 25 ° C. of 100,000 to 1,000,000 mPa · s, and preferably at least one radical polymerizable substance having a viscosity of 100,000 to 500,000 mPa · s. It may be. The viscosity of the radical polymerizable substance can be measured using a commercially available E-type viscometer.

The free radical generator is a compound that decomposes by heating or light to generate free radicals, such as a peroxide compound or an azo compound. The free radical generator is appropriately selected depending on the intended connection temperature, connection time, pot life, and the like. The free radical generator may be at least one selected from, for example, benzoyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, and hydroperoxide. From the viewpoint of high reactivity and pot life, the free radical generator is preferably an organic peroxide having a half-life of 10 hours at a temperature of 40 ° C or higher and a half-life of 1 minute at a temperature of 180 ° C or lower. is there. The free radical generator may be used in combination with a decomposition accelerator, an inhibitor and 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 adhesive components.

When the adhesive component contains a radical curable material, it may further contain a polymerization inhibitor. 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.

Thermosetting resins are, for example, epoxy resins, cyanate ester resins, maleimide resins, allyl nadiimide resins, phenol resins, urea resins, melamine resins, alkyd resins, acrylic resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, Resorcinol formaldehyde resin, xylene resin, furan resin, polyurethane resin, ketone resin, triallyl cyanurate resin, polyisocyanate resin, resin containing tris (2-hydroxyethyl) isocyanurate, resin containing triallyl trimellitate And thermosetting resins synthesized from cyclopentadiene, thermosetting resins by trimerization of aromatic dicyanamide, and the like. These thermosetting resins are used alone or in combination of two or more. The content of the thermosetting resin may be, for example, 20 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 curing agent may be melamine and derivatives thereof, hydrazide-based curing agent, boron trifluoride-amine complex, sulfonium salt, amine imide, diaminomaleonitrile, polyamine salt, dicyandiamide, etc., or modified products thereof. Or in combination of two or more. The curing agent may be a polyaddition type curing agent such as polyamines, polymercaptans, polyphenols, and acid anhydrides, or a polyaddition type curing agent and a catalyst type curing agent may be used in combination. . The content of the curing agent may be 0.5 to 15% by mass based on the total amount of the adhesive component.

Because these hardeners are coated with a polymer material such as polyurethane or polyester, or a metal thin film such as Ni or Cu, and an inorganic material such as calcium silicate, the pot life can be extended. preferable.

The adhesive component may further contain a filler such as silicone particles, a softener, an accelerator, an anti-aging agent, a colorant, a flame retardant, a thixotropic agent, a coupling agent and the like.

In the case where the adhesive composition is formed into a film shape, the adhesive component may contain a resin having a functional group such as a hydroxyl group in order to improve the film formability. Such resins are polystyrene, polyethylene, polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyester, polyvinyl chloride, polyphenylene oxide, urea resin, melamine resin, phenol resin, xylene resin, epoxy resin, polyisocyanate resin, phenoxy resin. , Polyimide resin, polyester urethane resin, polyurethane resin, etc. From the viewpoint of further improving the connection reliability, a high molecular weight epoxy resin or phenoxy resin having a weight average molecular weight of 10,000 or more determined by high performance liquid chromatography (HPLC) It may be. The adhesive component may contain those resins modified with radically polymerizable functional groups, or contain a mixture of these resins and a styrene resin or acrylic resin for melt viscosity adjustment, etc. May be. In another embodiment, the adhesive component may contain rubber to enhance film formability.

FIG. 2 is a cross-sectional view schematically showing an embodiment of the conductive particles 3 included in the adhesive film 1. As shown in FIG. 2A, the conductive particle 3 </ b> A includes a plastic particle 31 and a metal layer 32 </ b> A that covers the plastic particle 31 in one embodiment.

It is preferable that substantially the entire surface of the plastic particle 31 is covered with the metal layer 32A. However, the plastic particle 31 may be used as long as the function as a circuit connecting material (function of electrically connecting circuit members) is maintained. A part of the surface of the particle 31 may be exposed without being covered with the metal layer 32A.

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

The diameter of the plastic particles 31 is preferably 1 μm or more on average and may be 40 μm or less. 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 there are variations in the surface irregularities of the electrodes, 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 is composed of, for example, a single metal layer. The metal layer 32A is made 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 32 </ b> A means the thickness in the portion of the metal layer where the protrusions described later are not formed. The thickness of the metal layer 32A can be measured with an electron microscope.

As shown in FIG.2 (b), in the electroconductive particle 3B of other one Embodiment, the metal layer 32B is a metal layer which consists of two layers, the 1st metal layer 32a and the 2nd metal layer 32b, Good. That is, the conductive particle 3B according to another embodiment includes a plastic particle 31, a first metal layer 32a that covers the plastic particle 31, and a second metal layer 32b that covers the first metal layer 32a. It has.

The first metal layer 32a is made of, for example, Ni. The second metal layer 32b may be formed of, for example, Au or Pd, and is preferably formed of Pd from the viewpoint of further improving the reliability. That is, the conductive particle 3B may have a layer formed of Au or Pd on the outermost surface of the conductive particle 3B as a metal layer. From the viewpoint of further improving the reliability, the conductive particle 3B is preferably made of Pd. It has a layer that is formed.

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 less, or 50 nm or less, 2 to 200 nm, 2 to 100 nm, 2 nm, or 2 nm. It may be ˜50 nm, 5˜200 nm, 5˜100 nm, 5˜50 nm, 10˜200 nm, 10˜100 nm, or 10˜50 nm. The thickness of the 1st metal layer 32a and the 2nd metal layer 32b means the thickness in the part of the metal layer in which the projection part mentioned later is not formed, respectively. The thickness of the first metal layer 32a and the second metal layer 32b can be measured with 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. 2A, the protrusion 33A is composed of a single metal layer 32A. In the conductive particle 3B shown in FIG. 2B, the protrusion 33B is composed of a metal layer 32B composed of two layers, a first metal layer 32a and a second metal layer 32b.

The height of the protrusion 33 is 85 nm or more, 90 nm or more, or 100 nm or more from the viewpoint of improving the reliability of electrical connection, 1200 nm or less, 1000 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, Or it is 200 nm or less. From the same viewpoint, the height of the protrusion 33 is 85 to 1200 nm, 85 to 1000 nm, 85 to 600 nm, 85 to 500 nm, 85 to 400 nm, 85 to 300 nm, 85 to 200 nm, 90 to 1200 nm, 90 to 1000 nm, 90 -600 nm, 90-500 nm, 90-400 nm, 90-300 nm, 90-200 nm, 100-1200 nm, 100-1000 nm, 100-600 nm, 100-500 nm, 100-400 nm, 100-300 nm, or 100-200 nm Good.

Here, the height of the protrusion 33 is determined by analyzing a two-dimensional image including a projected image of conductive particles. The analysis of the two-dimensional image can be performed according to the method described in JP-A-2016-61722.

Specifically, for example, a step of detecting a particle edge that is a boundary between a projection image of each conductive particle and another region in a two-dimensional image obtained by imaging a plurality of conductive particles, and two steps based on the particle edge. A step of calculating the center coordinates of the conductive particles on the three-dimensional image, and dividing the particle edge into a plurality of particle edge portions (for example, twelve) for each predetermined angle around the center coordinate, and for each of the plurality of particle edge portions And calculating the difference between the maximum value and the minimum value of the distance between the center coordinate and the particle edge, calculating the average value of the differences as the height of the protrusion, and a plurality of conductive particles (for example, 5 to 100 particles). A step of calculating an average value of the heights of the protrusions calculated for the arbitrary number of projections).

In the above-described analysis of the two-dimensional image, the particle edge substantially corresponds to the outer periphery including the irregularities derived from the protrusions of the two-dimensional projection image of the conductive particles. A luminance frequency distribution obtained from a two-dimensional image generally shows a local minimum value reflecting a particle edge portion. The two-dimensional image is binarized using the luminance corresponding to the minimum value as the first threshold value to generate a binarized image. Edges formed in the obtained binarized image are detected as particle edges. Based on the particle edges, the center coordinates of the conductive particles on the two-dimensional image are calculated. A circle to be fitted to the particle edge is obtained by the method of least squares, and the center of the circle is set as the center coordinate of the conductive particle.

From the viewpoint of further improving the reliability of electrical connection, the area ratio of the protrusions 33 (area ratio of the protrusions 33) to the entire projected image of the surface of the conductive particles 3 is preferably 8% or more and 9%. Or more, 20% or more, preferably 60% or less or 50% or less, preferably 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 conductive particles according to the method described in JP-A-2016-61722. The area ratio of the protrusions is obtained by, for example, calculating a second threshold corresponding to the boundary between the protrusion and the other part from the luminance frequency distribution in the region inside the particle edge, and the obtained second threshold And binarizing the area inside the particle edge to generate a binarized image, and in the obtained binarized image, the ratio of the area of the area corresponding to the protrusion to the area inside the particle edge And a step of calculating the area ratio of the protrusions.

The conductive particles 3 having protrusions as described above can be obtained, for example, by forming the

metal layers

32A and 32B on the surface of the plastic particles 31 by metal plating. At the time of metal plating, the protruding portion 33 can be formed by changing the plating conditions and changing the thickness of the

metal layers

32A and 32B. For example, the protrusion 33 can be formed by gradually increasing the concentration of the plating solution in the process of metal plating.

Alternatively, by adjusting the pH of the plating solution, for example, by setting the pH of the nickel plating solution to 6, a metal layer having a knurled protrusion can be formed (Mochizuki et al., Surface Technology, Vol. 48, No. 4, pages 429 to 432, 1997). When glycine is used as a complexing agent that contributes to the stability of the plating bath, a metal layer having a flat surface is formed, whereas when tartaric acid or DL-malic acid is used as the complexing agent, a hump is formed. (For example, Sugawara et al., Amorphous Plating, Vol. 36, pp. 35-37, 1994; Sugawara et al., Journal of Circuit Packaging Society, Vol. 10, No. 3, 148-152. Page 1995). By adopting these methods, the

metal layers

32A and 32B having the protrusions 33 having a desired height and area ratio can be formed.

When producing the conductive particles 3B shown in FIG. 2B, for example, after forming the first metal layer 32a having the protrusions by the above method, the Au or Pd layer is formed by displacement plating. Thus, the second metal layer 32b can be obtained.

The content of the conductive particles 3 contained in the adhesive film 1 is determined according to the definition of the electrode to be connected. The content of the conductive particles 3 may be, for example, 1 part by volume or more and 50 parts by volume or less with respect to 100 parts by volume of the adhesive component, which is preferable from the viewpoint of insulation and manufacturing cost. Is 30 parts by volume or less.

The adhesive composition may be a multilayer film (multilayer adhesive film). The multilayer adhesive film may have a two-layer structure including, for example, a layer containing conductive particles and a layer not containing conductive particles, and is provided on both sides of the layer containing conductive particles. A three-layer configuration including a layer not including conductive particles may be used. The multilayer adhesive film may include a plurality of layers including conductive particles. The multilayer adhesive film may include an adhesive layer exhibiting high adhesiveness to the circuit member to be connected in consideration of adhesiveness with the circuit member. When these multilayer adhesive films are used, the conductive particles can be efficiently captured on the connection electrodes, which is advantageous for connecting narrow pitch circuit members.

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

Next, a method for manufacturing a connected body using the adhesive film 1 will be described. Drawing 3 is a sectional view showing typically the manufacturing method of the connecting object concerning one embodiment. First, as shown to Fig.3 (a), the 1st circuit member 4, the 2nd circuit member 5, and the 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 arranged so that the first connection terminal 7 and the second connection terminal 9 face each other, and the first circuit member 4 and the second circuit member 5 are arranged. The adhesive film 1 is disposed between the circuit member 5 and a laminate.

Then, the adhesive film 1 is cured while pressurizing the entire laminate in the direction indicated by the arrow in FIG. The pressure at the time of pressurization may be, for example, 1 to 10 MPa per total connection area. The method of curing the adhesive film 1 may be a method by heating, or a method of using light irradiation in combination with heating. Heating may be performed at 100 to 170 ° C., for example. Pressurization and heating (light irradiation as necessary) may be performed, for example, for 1 to 160 seconds. Thereby, the 1st circuit member 4 and the 2nd circuit member 5 are crimped | bonded via the hardened | cured material of the adhesive composition which comprises the adhesive film 1. FIG.

In the present embodiment, the adhesive film 1 is disposed between the first circuit member 4 and the second circuit member 5, but as another embodiment, instead of the adhesive film, a paste adhesive composition The object may be applied on the first circuit member 4 or the second circuit member 5, or both.

As shown in FIG. 3B, the connection body 10 according to the embodiment obtained in this way includes the first substrate 6 and the first connection terminal 7 provided on the first substrate 6. The second circuit member 5 having the first circuit member 4, the second substrate 8 and the second connection terminal 9 provided on the second substrate 8, the first circuit member 4 and the second circuit member 5. The connection part which is provided between the circuit member 5 and electrically connects the first circuit member 4 (first connection terminal 7) and the second circuit member 5 (second connection terminal 9) to each other. 11. The connection part 11 is comprised by the hardened | cured material of the adhesive composition, and consists of the hardened | cured material 12 of the adhesive component 2, and the electroconductive particle 3 disperse | distributed in this hardened | cured material 12. FIG. In the connection body 10, since the conductive particles 3 are interposed between the first connection terminal 7 and the second connection terminal 9, the first connection terminal 7 and the second connection terminal 9 are electrically connected to each other. It is connected to the.

The first substrate 6 may be, for example, an IC chip 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.

More specifically, as a combination of the first substrate 6 and the second substrate 8, the first substrate 6 may be an IC chip or a flexible substrate, and the second substrate 8 may be a flexible substrate. Alternatively, the first substrate 6 may be an IC chip 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 chip or a flexible substrate. When the first substrate 6 is an IC chip and the second substrate 8 is a flexible substrate, the above-described adhesive film 1 is used for COP (Chip-on-Plastic-substrate) connection. When the first substrate 6 and the second substrate 8 are flexible substrates, the above-mentioned adhesive film 1 is used for FOP (Film on Plastic substrate) connection.

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

The flexible substrate may further have a modified film such as a hard coat and / or a protective film formed on the surface of the organic base material for improving optical and mechanical properties. In order to facilitate handling and conveyance of the flexible substrate, a reinforcing material selected from a glass substrate and SUS or the like may be bonded to the organic substrate.

The thickness of the flexible substrate is preferably 10 μm or more, 200 μm or less, or 125 μm or less from the viewpoint of securing the strength as a film and the ease of bending of the substrate alone.

When conventional circuit connection materials are used, the electrodes on the flexible substrate may be easily broken or cracked by heating and pressurization for crimping the circuit members. In addition, regarding the connection of electrodes for which it is difficult to form a sufficient electrical connection, it is necessary to crimp the circuit member under a condition of lower temperature or lower stress in order to suppress damage to the electrodes. The circuit connection material (adhesive film) of the present embodiment can have an advantageous effect as compared with conventional materials in these respects.

The glass substrate may be formed of soda glass, quartz glass, or the like, and may be a substrate subjected to chemical strengthening treatment from the viewpoint of preventing damage due to external stress. The composite substrate may include a glass substrate and an insulating film formed on the surface of the glass substrate and made of polyimide or a colored organic or inorganic material for decoration. It may be formed on an insulating film.

When the second substrate 8 is a flexible substrate, the first substrate 6 is an electronic component such as an active element such as a semiconductor chip, a transistor, a diode, or a thyristor, a passive element such as a capacitor, a resistor, or a coil, or a printed circuit. It may be a substrate or the like. When the first substrate 6 is an IC chip, the tip of a bump or gold wire formed by plating is melted with a torch or the like to form a gold ball, and the wire is pressed onto the electrode pad, and then the wire is cut. Protruding electrodes (first connection terminals 7) such as wire bumps obtained in this way can be provided and used as the first circuit member 4.

Examples of electrode materials for forming the first connection terminal 7 and the second connection terminal 9 include Ag paste, metals such as Ni, Al, Au, Cu, Ti, and Mo, metal oxides such as ITO and IZO, and silver nanowires. And conductors such as carbon nanotubes. The first connection terminal 7 and the second connection terminal 9 may be formed of the same material or different materials, but are preferably the same material. On the first connection terminal 7 and the second connection terminal 9, a surface layer formed of an oxide, a nitride, an alloy, an organic substance, or the like may be further provided from the viewpoint of preventing disconnection. Each of the first circuit member 4 and the second circuit member 5 may be provided with one first connection terminal 7 or one second connection terminal 9, but preferably a predetermined interval is formed. Many are provided.

When the circuit connection material (adhesive film) is used, the first circuit member 4 is an FPC circuit board, and the second connection terminal 9 in the second circuit member 5 ensures sufficient electrical connection. Even when it is formed of a metal oxide that tends to be difficult, a more reliable electrical connection can be obtained.

FIG. 4 is a cross-sectional view schematically showing a main part of the connection body 10 according to an embodiment. As shown in FIG. 4, when the circuit members are connected to each other by connecting the circuit members to each other, the height of the protrusion 33 of the conductive particle 3 is within a predetermined range. Since the conductive particles 3 interposed therebetween can apply sufficient pressure to the first connection terminal 7 and the second connection terminal 9 (and the second substrate 8) by the protrusions 33, higher reliability can be achieved. For example, it is considered that the increase in connection resistance under high temperature and high humidity is unlikely to occur.

On the other hand, as shown in FIG. 5 (a cross-sectional view schematically showing a main part of a conventional connection body), in the conventional connection body 20, the conductive particles 23 have a relatively low protrusion 23a. Sufficient pressure cannot be applied to the first connection terminal 7 and the second connection terminal 9 (and the second substrate 8). Therefore, the conventional connection body 20 is inferior in the reliability of electrical connection.

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

(Preparation of conductive particles)
(1) Plastic particles Using tetramethylolmethane tetraacrylate, divinylbenzene, and styrene as monomers and polymerizing them by suspension polymerization using a polymerization initiator (benzoyl peroxide), plastic particles were obtained.

(2-1) Conductive particles 1-1 to 1-3
The obtained plastic particles were subjected to electroless Ni plating to obtain conductive particles 1 to 3 each having a protrusion and a metal layer (Ni layer, thickness 0.2 μm) formed of Ni. During the Ni plating process, the protrusions having different heights and area ratios were formed by changing the thickness of the Ni layer by appropriately adjusting the amount of plating solution charged, the processing temperature, and the processing time.

(2-2) Conductive particles 1-4 to 1-6
On the Ni layer of each of the conductive particles 1 to 3, conductive layers 4 to 6 were obtained by forming Au layers (Au layers) having protrusions by displacement plating.

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

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

(3) Height and area ratio of protrusion part The two-dimensional image containing each electroconductive particle was acquired with the scanning electron microscope. By analyzing the obtained two-dimensional locus image by the method described in JP-A-2016-61722, the height and area ratio of the protrusions of 100 conductive particles are calculated, and the average value thereof is obtained. It was.

(Production of adhesive film (circuit connection material))
20 parts by mass of urethane acrylate (product name: UA-5500T, manufactured by Shin-Nakamura Chemical Co., Ltd.), a bis (acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.) 15 parts by mass, 5 parts by mass of dimethylol tricyclodecane diacrylate (product name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.) and 2-methacryloyloxyethyl acid phosphate (product name: P-2M, Kyoeisha Chemical Co., Ltd.) 1 part by mass of Kyoeisha Chemical Co., Ltd.), 8 parts by mass of benzoyl peroxide (product name: Nyper BMT-K, manufactured by NOF Corporation) and polyester urethane resin (product name: UR4800, manufactured by Toyobo Co., Ltd.) 60 parts by mass of a 40% by weight solution was mixed and stirred to obtain a binder resin solution. The polyester urethane resin solution was 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 with respect to 100 parts by volume of the binder resin. Therein, silicone fine particles (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd.) having an average particle diameter of 2 μm are dispersed at a ratio of 20 parts by mass with respect to 100 parts by mass of the binder resin, and the binder resin, conductive property is dispersed. A coating solution containing particles and silicone fine particles was obtained. This coating liquid was applied to a polyethylene terephthalate (PET) film (thickness 50 μm) having a surface treated on one side using a coating apparatus. The coating film was dried by hot air drying at 70 ° C. to prepare an anisotropic conductive adhesive film (thickness: 18 μm) as a circuit connecting material.

(Preparation of circuit members)
-Glass member The glass member which has a glass substrate, Cu film | membrane (thickness 30nm) laminated | stacked in order on this glass substrate, and the connection terminal (thickness 40nm) of amorphous ITO was prepared.
-Flexible member A flexible member having a polyethylene terephthalate (PET) film (elastic modulus at 25 ° C .: 4600 MPa) and an ITO connection terminal (thickness 20 nm) formed on the PET film was prepared.
・ Flexible circuit board (FPC)
An FPC having a resin film substrate made of polyethylene terephthalate (PET) as a substrate and wiring provided on the resin film substrate was prepared. This FPC wiring is composed of a Cu layer having a pitch of 0.3 mm (space 0.15 mm, electrode width 0.15 mm, height 18 μm), a Ni plating layer 3 μm thick formed in order on the Cu layer, and a thickness of 0 It has a connection terminal composed of a 0.03 μm Au plating layer.

An anisotropic conductive adhesive film was sandwiched between the flexible member and the FPC. In this state, the flexible member and the FPC were connected by pressurizing the whole for 10 seconds at a pressure of 2 MPa per total connection area while heating the anisotropic conductive adhesive film to reach 160 ° C. A flexible / FPC connector was obtained.
Similarly, the glass member and FPC were connected by sandwiching an anisotropic conductive adhesive film between them to obtain a glass / FPC connector.

Each obtained connecting body was subjected to a reliability test of 85 ° C., 85% RH, 72 hours. About the connection body before and behind a test, the connection resistance between the circuit members which oppose was measured.

Tables 1 and 2 show characteristics such as the outermost surface layer, protrusion height, protrusion area ratio, and evaluation results of the obtained conductive particles.

DESCRIPTION OF SYMBOLS 1 ... Adhesive film, 2 ... Adhesive component, 3 ... Conductive particle, 4 ... 1st circuit member, 5 ... 2nd circuit member, 6 ... 1st board | substrate, 7 ... 1st connection terminal, 8 2nd substrate, 9 ... 2nd connection terminal, 10 ... connection body, 11 ... connection part, 31 ... plastic particle, 32A, 32B ... metal layer, 33, 33A, 33B ... projection part.

Claims

Containing an adhesive component and conductive particles;
The conductive particles have plastic particles and a metal layer covering the plastic particles;
An adhesive composition, wherein a plurality of protrusions are formed on a surface of the conductive particles, and the average height of the plurality of protrusions is 85 to 1200 nm.
2. The adhesive composition according to claim 1, wherein, in the projected 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 claim 1 or 2, wherein the conductive particles have a layer formed of Pd on the outermost surface of the conductive particles as the metal layer.
The adhesive composition according to claim 3, wherein the layer formed of Pd has a thickness of 2 to 200 nm.
A first circuit member having a first board and a first connection terminal provided on the first board; a second board and a second connection terminal provided on the second board; Used to electrically connect the second circuit members to each other;
The first substrate is an IC chip or a flexible substrate;
The second substrate is a flexible substrate containing at least one thermoplastic resin selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate. Adhesive composition.
A first circuit member having a first board and a first connection terminal provided on the first board; a second board and a second connection terminal provided on the second board; Used to electrically connect the second circuit members to each other;
The first substrate is an IC chip or a flexible substrate;
The adhesive composition according to any one of claims 1 to 4, wherein 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 first circuit member having a first substrate and a first connection terminal provided on the first substrate; and being disposed to face the first circuit member; A circuit connecting material is disposed between the second circuit member and the second circuit member provided on the substrate to produce a laminate, and the laminate is heated and pressurized to obtain the first Electrically connecting the 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 a metal layer covering the plastic particles;
A method for manufacturing a connection body, wherein a plurality of protrusions are formed on a surface of the conductive particles, and the average height of the plurality of protrusions is 85 to 1200 nm.
The method for manufacturing a connection body according to claim 7, wherein, in the projected image of the conductive particles, a ratio of an area of the protruding portion to an area of the surface of the conductive particles is 8 to 60%.
The method for producing a connection body according to claim 7 or 8, wherein the conductive particles have a layer formed of Pd on the outermost surface of the conductive particles as the metal layer.
The method for manufacturing a connection body according to claim 9, wherein the layer formed of Pd has a thickness of 2 to 200 nm.
The first substrate is an IC chip or a flexible substrate;
The second substrate is a flexible substrate containing at least one thermoplastic resin selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate. A method for manufacturing a connector.
The first substrate is an IC chip or a flexible substrate;
The method for producing a connection body according to any one of claims 7 to 10, wherein the second substrate is a glass substrate or a composite substrate having a glass substrate and an insulating film provided on the glass substrate. .