KR20230009896A - Conductive adhesive, manufacturing method of circuit connection structure and circuit connection structure - Google Patents

Abstract

A conductive adhesive contains an adhesive composition and conductive particles, and the compression hardness of the conductive particles at 20% compression is 10.0 GPa or more at 25°C and 3.5 GPa or less at 150°C.

Description

Conductive adhesive, manufacturing method of circuit connection structure and circuit connection structure

The present disclosure relates to a conductive adhesive, a method for manufacturing a circuit connection structure, and a circuit connection structure.

In recent years, there is a demand for an enlarged viewing angle and low power consumption of displays, and development of self-luminous displays such as organic EL displays is in progress. In the organic EL display, a system for inputting electric signals from FPC (Flexible printed circuits) is adopted, as in the liquid crystal panel, and in such a system, a large current of several tens of mA to 200 mA is applied to one connection terminal. is flowing Therefore, as the electrode on the side of the organic EL display, a transparent electrode such as ITO on a glass substrate and a metal film having a thickness of several tens to several thousand nm are further used on the glass substrate, and it is designed so that a sufficient electric value can be obtained (e.g. For example, see Patent Document 1).

By the way, circuit connection materials are normally used for connection between the electrodes of the FPC and the electrodes on the display side. As a circuit connection material, a conductive adhesive having an anisotropic conductivity containing an adhesive composition and conductive particles is known, for example. According to such a circuit connection material, electrodes can be connected with low resistance by conductive particles.

Patent Document 1: Japanese Patent Publication No. 3641342

Demand for low power consumption of displays is increasing, and circuit connection materials exhibiting lower resistance than before are required. In addition, as circuit densification increases, circuit connection materials are also required to have excellent connection reliability such that connection resistance after connection does not increase.

Accordingly, an object of the present disclosure is to provide a conductive adhesive that exhibits low resistance in connection of opposing electrodes and can obtain good connection reliability. Another object of this indication is to provide the circuit connection structure manufacturing method and circuit connection structure using such a conductive adhesive agent.

In order to solve the above problems, one aspect of the present disclosure contains an adhesive composition and conductive particles, and the compression hardness of the conductive particles at 20% compression is 10.0 GPa or more at 25 ° C and 3.5 GPa at 150 ° C. The following conductive adhesives are provided.

According to the conductive adhesive described above, low resistance is exhibited in connection of opposing electrodes, and good connection reliability can be obtained. The reason why such an effect is obtained is not necessarily clear, but the present inventors speculate as follows. Conductive particles contained in the conductive adhesive have a compression hardness that satisfies the above conditions at two predetermined temperatures, so that the conductive particles can make sufficient contact with the electrode when mounting by thermal compression bonding is performed. It is considered that hardness and softness in which resistance increase due to repulsion of conductive particles immediately after mounting is difficult to occur can be expressed, thereby achieving both reduction in connection resistance and improvement in connection reliability.

The conductive particles may have a compression recovery rate of 50 to 75% at 25°C.

The conductive particles may have an average particle diameter of 2 μm or more and 10 μm or less.

When a conductive adhesive is used for connection between circuit electrodes, the connection may be a Flex on Glass connection, a Flex on Flex connection, or a Flex on Polymer connection.

In another aspect of the present disclosure, the conductive adhesive according to the present invention is interposed between a first circuit member having a first circuit electrode and a second circuit member having a second circuit electrode, and the first circuit member and It is related with the manufacturing method of the circuit connection structure provided with the process of electrically connecting a 1st circuit electrode and the said 2nd circuit electrode by thermocompression-bonding a 2nd circuit member.

According to the manufacturing method of the circuit connection structure described above, a circuit connection structure having low resistance and excellent connection reliability can be obtained by using the conductive adhesive according to one aspect of the present disclosure.

In the manufacturing method of said circuit connection structure WHEREIN: At least one of a 1st circuit electrode and a 2nd circuit electrode may have the layer containing Ti on the surface.

Titanium has excellent conductivity, and is suitable for circuit forming materials in terms of magnetism, strength, ductility and malleability, and also has excellent corrosion resistance, chemical stability, physical stability, Since it is a metal that exhibits gas barrier properties and diffusion barrier properties at a dissimilar metal interface, it is easier to obtain a circuit connection structure that can handle large currents.

Furthermore, when the electrode is formed of an electrode material containing titanium, the inventors of the present invention tend to find that coexistence of reducing the connection resistance and securing the connection reliability becomes more difficult in conventional circuit connection materials in which conductive particles are blended. is revealed by On the other hand, according to the conductive adhesive according to one aspect of the present disclosure, it is possible to achieve both reduction in connection resistance and securing of connection reliability even in the case of connecting an electrode having a Ti-containing layer on the surface. Therefore, according to the method according to another aspect of the present disclosure, a circuit connection structure corresponding to the above characteristics can be obtained while achieving both reduction in connection resistance and ensuring connection reliability.

Another aspect of the present disclosure includes a first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and a connection portion interposed between the first circuit member and the second circuit member. And, it relates to a circuit connection structure in which the connecting portion is a cured product of the conductive adhesive according to one aspect of the present disclosure.

In the circuit connection structure described above, when the connection portion is a cured product of the conductive adhesive according to the present invention, low resistance and excellent connection reliability can be obtained.

In the circuit connection structure described above, at least one of the first circuit electrode and the second circuit electrode may have a Ti-containing layer on the surface.

According to the present disclosure, it is possible to provide a conductive adhesive that exhibits low resistance in connection of opposing electrodes and can obtain good connection reliability. The present disclosure can also provide a circuit connection structure having low resistance and excellent connection reliability and a method for manufacturing the same, using such a conductive adhesive. The circuit connection structure can sufficiently ensure connection reliability even when exposed to a high-temperature, high-humidity environment, and is useful for reducing power consumption.

1 is a schematic diagram showing a method for calculating a compression recovery rate of conductive particles.
2 is a graph showing an example of a compression curve of conductive particles.
Fig. 3 is a process cross-sectional view schematically showing a manufacturing method of a circuit connection structure according to an embodiment of the present disclosure.

Hereinafter, preferred embodiments of the present invention will be described in detail, referring to the drawings where necessary. However, this invention is not limited to the following embodiment.

In addition, in this specification, “(meth)acrylate” means an acrylate or a methacrylate corresponding thereto. Similarly, "(meth)acryloxy" means acryloxy or methacryloxy corresponding thereto. With "A or B", either one of A and B may be included, and both may be included.

In addition, in this specification, the numerical range expressed using "-" shows the range which includes the numerical value described before and after "-" as a minimum value and a maximum value, respectively. In addition, in the numerical range described step by step in this specification, the upper limit or lower limit of the numerical range of a given stage may be replaced with the upper limit or lower limit of the numerical range of another stage. In addition, in the numerical range described in this specification, you may replace the upper limit value or the lower limit value of the numerical range with the value shown in the Example.

<Conductive adhesive>

The conductive adhesive of this embodiment contains conductive particles and an adhesive composition.

(conductive particle)

As the conductive particles, those having a compression hardness of 10.0 GPa or more at 25°C and 3.5 GPa or less at 150°C can be used at 20% compression. In addition, the compression hardness of conductive particles is an index of the hardness of conductive particles.

The compression hardness (hereinafter sometimes referred to as "K value") of the conductive particles can be measured using a micro compression tester (device name: Fischer HM2000, manufactured by Fischer Instruments). Specifically, first, conductive particles are sprayed onto a slide glass (product name: S1214, manufactured by Matsunami Glass Kogyo Co., Ltd.) on a stage set to a predetermined temperature (eg, 25° C., 150° C.). And, when one particle is selected from among them and compressed at a rate of 0.33 mN/sec from the center with an initial load of 0.1 mN using a prismatic diamond indenter having a square bottom surface with a side of 50 μm, It can be obtained from the stress-strain curve. Specifically, when the load F (N), the displacement S (mm), the particle radius R (mm), the elastic modulus E (Pa), and the Poisson's ratio σ, the compression formula of the elastic sphere

F=(2 ^1/2 /3)×(S ^3/2 )×(E×R ^1/2 )/(1-σ ² )

Using , the following formula

K=E/(1-σ ² )=(3/2 ^1/2 )×F×(S ^-3/2 )×(R ^-1/2 )

can be obtained from In addition, when the strain X (%) and the sphere diameter D (μm) are used, the following equation

K=3000F/(D ^2× X ^3/2 )×10 ⁶

The K value at any strain can be obtained by Strain X is,

X=(S/D)×100

is calculated by The maximum test load in the compression test is set to 50 mN, for example.

The K value at 20% compression is obtained by setting the strain X to 0.2.

The conductive particles may have a compression hardness of 10.0 GPa or more at 25°C at 20% compression, may be 10.0 to 20.0 GPa, may be 10.0 to 15.0 GPa, may be 10.0 to 13.0 GPa, or may be 10.5 to 12.0 GPa. If the K value at the time of 20% compression of the conductive particles at 25°C (hereinafter sometimes referred to as the K value (25°C, 20%)) is within the above range, when connecting the opposing electrodes, the conductive particles may It tends to be appropriately flattened between them, making it easy to secure the contact area between the electrode and the conductive particles, making it easy to further improve connection reliability.

The conductive particles may have a compression hardness of 3.5 GPa or less at 150° C., 1.0 to 3.5 GPa, 1.5 to 3.2 GPa, 1.8 to 3.0 GPa, or 2.0 to 3.0 GPa at 150° C. at 20% compression. If the K value at 20% compression of the conductive particles at 150°C (hereinafter sometimes referred to as the K value (150°C, 20%)) is within the above range, the conductive particles immediately after mounting exhibit appropriate softness, , resistance increase due to repulsion of the conductive particles tends to be less likely to occur, making it easier to further improve connection reliability.

The conductive particles may have a compression recovery rate (compression set recovery rate) at 25°C of more than 40%, 45% or more, 50% or more, 70% or more, 80% or less, or 75% It may be less than or equal to 60%. The compression recovery rate of the conductive particles at 25°C may be within the range of the combination of the lower limit value and the upper limit value, for example, greater than 40% and less than or equal to 80%, 45 to 80%, or 50 to 75%. , 70 to 75% may be sufficient, and may be 55 to 60%.

The compression recovery factor can be measured, for example, using a micro compression tester (apparatus name: Fischer HM2000, manufactured by Fischer Instruments). Specifically, first, conductive particles are sprayed onto a slide glass (product name: S1214, manufactured by Matsunami Glass Kogyo Co., Ltd.) on a stage set at 25°C. Then, one particle is selected from among them, and a load of 5 mN is applied at a rate of 0.33 mN/sec from the center with an initial load of 0.1 mN using a prismatic diamond indenter having a square bottom surface of 50 μm on one side. The compression recovery rate can be measured by measuring the relationship between the load value and the compression displacement in the process of reducing the load to the value of the initial load at a rate of 0.33 mN/sec.

This is explained using drawings. 1 is a schematic diagram showing a method for calculating a compression recovery factor of conductive particles. On the other hand, Fig. 2 is a graph showing an example of a compression curve of conductive particles. 1 and 2, L2 is the displacement from the initial load (load 0.1 mN) to the load reversal (load 5 mN), and the displacement from the load reversal to the final load (load 0.1 mN) is The value of L1/L2×100 (%) when L1 is taken as the compression recovery factor. This operation is performed for 10 conductive particles and the average value is taken to calculate the compression recovery factor in the present embodiment.

The conductive particles are not particularly limited, but examples thereof include core-shell particles having plastic particles and a metal layer covering the plastic particles. The metal layer does not have to cover the entire surface of the plastic particle, and may cover a part of the surface of the plastic particle.

The plastic particles are, for example, acrylic resins such as polymethyl methacrylate and polymethyl acrylate, polyolefin resins such as polyethylene, polypropylene, polyisobutylene and polybutadiene, polystyrene resins, and polyester resins. , polyurethane-based resin, polyamide-based resin, epoxy-based resin, polyvinyl butyral-based resin, rosin-based resin, terpene-based resin, phenol-based resin, guanamine-based resin, melamine-based resin, oxazoline-based resin, carbodies and those formed from at least one type of resin selected from the group consisting of mead-based resins, silicone-based resins, and the like. Further, as the plastic particles, a composite of such a resin and an inorganic substance such as silica may be used.

As the plastic particles, from the viewpoint of the ease of control of the compression recovery rate and compression hardness (K value), plastic particles made of a resin obtained by polymerizing one type of polymerizable monomer having an ethylenically unsaturated group, or polymerization having an ethylenically unsaturated group Plastic particles made of a resin obtained by copolymerizing two or more types of sex monomers can be used. When obtaining a resin by copolymerizing two or more types of polymerizable monomers having ethylenically unsaturated groups, a non-crosslinkable monomer and a crosslinkable monomer are used in combination and the copolymerization ratio and type thereof are appropriately adjusted to facilitate the compression recovery rate and compression hardness of plastic particles. can be controlled Also, by using plastic particles containing two or more types of resin, the compression hardness may be adjusted so that the conductive particles satisfy the above-mentioned conditions of K value (25°C, 20%) and K value (150°C, 20%). do. As the said non-crosslinkable monomer and said crosslinkable monomer, the monomer described in Unexamined-Japanese-Patent No. 2004-165019 can be used, for example.

The average particle diameter of the plastic particles may be 1 μm to 10 μm. In addition, from the viewpoint of high-density packaging, the average particle diameter of the plastic particles may be 1 to 5 μm. In addition, from the viewpoint of maintaining a more stable connection state when unevenness on the surface of the electrode exists, the average particle diameter of the plastic particles may be 2 to 5 μm.

In the present embodiment, the average particle diameter of the particles can be obtained as follows. That is, one particle is randomly selected, observed under a differential scanning electron microscope, and its maximum and minimum diameters are measured. The square root of the product of this maximum diameter and minimum diameter is taken as the particle diameter of the particle. In this way, the average particle diameter of the particles can be obtained by measuring the particle diameter of 50 randomly selected particles and taking the average value.

The metal layer can be formed of, for example, at least one metal selected from the group consisting of Ni, Au, Pd, W, Cu, and NiB. The metal layer is, for example, a Ni layer, a Ni layer/Au layer (an aspect in which an Au layer is provided on the Ni layer. The same applies hereinafter), a Ni layer/Pd layer, a Ni layer/W layer, a Cu layer, and a NiB layer. You may have one or two or more layers selected from the group which consists of. The metal layer is formed by a general method such as plating, vapor deposition, or sputtering, and may be a thin film. Further, from the viewpoint of improving insulation between adjacent electrodes, the conductive particles may have a layer of an insulating material such as silica or acrylic resin covering the metal layer outside the metal layer.

The thickness of the metal layer may be 10 to 1000 nm, 20 to 200 nm, or 50 to 150 nm from the viewpoint of achieving a balance between conductivity and price. In the case where a layer of insulating material or an adhesive layer formed by adhering insulating fine particles is further provided on the metal layer, the thickness may be about 50 to 1000 nm. The thickness of these layers can be measured by, for example, a scanning electron microscope (SEM), a transmission electron microscope (TEM), an optical microscope or the like.

The average particle diameter of the conductive particles may be 2 to 10 μm, 2 to 8 μm, 2 to 6 μm, or 2 to 5 μm. If the average particle size of the conductive particles is within the above range, for example, when the conductive adhesive of the present embodiment is used as a circuit connection material, the particle size of the conductive particles can be made lower than the electrode height of the circuit member to be connected, and the distance between adjacent electrodes can be reduced. It becomes easy to further reduce a short circuit.

The content of the conductive particles in the conductive adhesive may be 0.1 to 30 parts by volume, 0.25 to 25 parts by volume, or 0.5 to 20 parts by volume when the total volume of the conductive adhesive is 100 parts by volume. When the content of the conductive particles is within the above range, for example, when the conductive adhesive of the present embodiment is used as a circuit connection material, it becomes easy to achieve both conductivity between opposing electrodes and insulation between adjacent electrodes with a good balance.

(adhesive composition)

Although it does not specifically limit as an adhesive composition, For example, you may have thermosetting property or photocurability. As the thermosetting adhesive composition, for example, a composition containing an epoxy resin and a latent curing agent of the epoxy resin (hereinafter referred to as "first composition"), a radical polymerizable substance and free radicals by heating. A composition containing a curing agent to be generated (hereinafter referred to as "second composition"), or a mixed composition of the first composition and the second composition is exemplified.

As the epoxy resin contained in the first composition, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolac type epoxy resins, alicyclic epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, aliphatic chain epoxy resins, and the like. can Such an epoxy resin may be halogenated or hydrogenated. Such an epoxy resin may use 2 or more types together.

The latent curing agent contained in the first composition may be one capable of curing an epoxy resin, and examples of such a latent curing agent include an anionic polymerizable catalyst type curing agent, a cationically polymerizable catalyst type curing agent, and a polyaddition type curing agent. there is. These can be used individually or in mixture of 2 or more types. Among these, anionic or cationic polymerizable catalytic curing agents are preferable in terms of excellent rapid curing properties and unnecessary consideration of chemical equivalents.

Examples of anionic or cationic polymerizable catalytic curing agents include imidazole-based curing agents, hydrazide-based curing agents, boron trifluoride-amine complexes, sulfonium salts, amineimides, diaminomaleonitrile, melamine and its derivatives, and polyamine salts. , dicyandiamide, and the like, and modified products thereof can also be used. Polyamines, polymer captans, polyphenols, acid anhydrides, etc. are mentioned as a curing agent of polyaddition type.

When tertiary amines, imidazoles, etc. are blended as an anionic polymeric catalyst-type curing agent, the epoxy resin is cured by heating at a medium temperature of about 160 ° C to 200 ° C for several tens of seconds to several hours. For this reason, pot life (pot life) can be made comparatively long. Examples of cationic polymerizable catalyst-type curing agents include photosensitive onium salts (aromatic diazonium salts, aromatic sulfonium salts, etc.) that cure epoxy resins by irradiation with energy rays. In addition to irradiation with energy rays, examples of materials that are activated by heating to cure the epoxy resin include aliphatic sulfonium salts and the like. This type of curing agent is preferable in that it has a feature of fast curing.

Microencapsulation of these latent curing agents by coating them with a polymeric material such as polyurethane or polyester, a metal film such as nickel or copper, or an inorganic material such as calcium silicate is preferable because the pot life can be extended. Do.

The blending amount of the latent curing agent contained in the first composition may be 20 to 80 parts by mass or 30 to 70 parts by mass based on 100 parts by mass of the epoxy resin and the film forming material to be blended as necessary.

The radically polymerizable substance contained in the second composition is a substance having a functional group that polymerizes with a radical. Examples of such a radically polymerizable substance include (meth)acrylate compounds, (meth)acryloxy compounds, maleimide compounds, citraconimide resins, and nadimide resins. A radically polymerizable substance may be used in the form of a monomer or an oligomer, and a combination of a monomer and an oligomer is also possible. Moreover, you may use polymerization inhibitors, such as hydroquinone and methyl ether hydroquinone, suitably as needed.

Specific examples of the (meth)acrylate compound include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, and ethylene glycol di(meth)acrylate. rate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, 2-hydroxy-1,3-di(meth)acrylate )Acrylicoxypropane, 2,2-bis[4-((meth)acryloxymethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane , dicyclopentenyl (meth) acrylate, tricyclodecanyl (meth) acrylate, tris ((meth) acryloyloxyethyl) isocyanurate, urethane (meth) acrylate and the like. . These can be used individually or in mixture of 2 or more types.

Moreover, from a viewpoint of improvement of heat resistance, a (meth)acrylate compound may have at least 1 sort(s) of substituent selected from the group which consists of a dicyclopentenyl group, a tricyclodecanyl group, and a triazine ring.

As for radically polymerizable substances other than the said (meth)acrylate compound, it is possible to use the compound of International Publication No. 2009/063827 suitably, for example. These are used individually by 1 type or in combination of 2 or more types.

In addition, a radically polymerizable substance having a phosphoric acid ester structure represented by the following general formula (I) can be used in combination with the above-mentioned radically polymerizable substance. In this case, since the adhesive strength to the surface of an inorganic substance such as metal is improved, it is suitable for bonding between circuit electrodes.

[Formula 1]

[In the formula, n represents an integer of 1 to 3.]

A radically polymerizable substance having a phosphoric acid ester structure is obtained by reacting phosphoric anhydride with 2-hydroxyethyl (meth)acrylate. As a radically polymerizable substance having a phosphoric acid ester structure, specifically, there are mono(2-methacryloyloxyethyl) acid phosphate, di(2-methacryloyloxyethyl) acid phosphate and the like. These can be used individually or in mixture of 2 or more types.

The compounding amount of the radically polymerizable substance having a phosphoric acid ester structure represented by the general formula (I) may be 0.01 to 50 parts by weight, or 0.5 parts by weight, based on 100 parts by weight in total of the radically polymerizable substance and the film-forming material to be blended as necessary. ~5 mass may be imparted.

The radically polymerizable substance may be used in combination with allyl (meth)acrylate. In this case, the blending amount of allyl (meth)acrylate may be 0.1 to 10 parts by mass, or 0.5 to 5 parts by mass, based on the total of 100 parts by mass of the radical polymerizable substance and the film forming material blended as necessary.

The curing agent that generates free radicals upon heating contained in the second composition is a curing agent that decomposes upon heating to generate free radicals. Examples of such curing agents include peroxides and azo compounds. Such a curing agent is appropriately selected depending on the target connection temperature, connection time, pot life, and the like. From the viewpoint of high reactivity and improvement of pot life, an organic peroxide having a half-life temperature of 40 ° C. or higher and a half-life temperature of 1 minute 180 ° C. or lower may be used, and a half-life temperature of 60 ° C. or higher for 10 hours. , an organic peroxide having a half-life of 1 minute at a temperature of 170° C. or less may be used.

The compounding amount of the curing agent may be 0.05 to 20 parts by mass, or 0.1 to 10 parts by mass, based on the total of 100 parts by mass of the radical polymerizable substance and the film forming material to be blended as necessary. Further, when the conductive adhesive of the present embodiment is used as a circuit connection material, the compounding amount of the curing agent may be 1 to 10 parts by mass based on 100 parts by mass in total of the radical polymerizable substance and the film forming material blended as necessary, 2 to 8 mass may be imparted. Thereby, a sufficient reaction rate can be obtained and the connection time can be made 25 seconds or less.

Specific examples of the curing agent contained in the second composition that generates free radicals upon heating include diacyl peroxide, peroxydicarbonate, peroxyester peroxyketal, dialkyl peroxide, hydroperoxide, silyl peroxide, and the like. can be heard Further, when the conductive adhesive of the present embodiment is used as a circuit connection material, from the viewpoint of suppressing corrosion of circuit electrodes, a curing agent having a concentration of 5000 ppm or less of chlorine ions and organic acids contained therein can be used. Curing agents low in organic acids can be used. Specific examples of such a curing agent include peroxy esters, dialkyl peroxides, hydroperoxides, silyl peroxides, and the like, and a curing agent selected from peroxy esters having high reactivity can be used. In addition, the said hardening|curing agent can mix suitably and can be used.

Examples of peroxy esters include cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, and t-hexylperoxyneodecanoate. Silperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, 2,5-dimethyl-2,5-di(2- Ethylhexanoylperoxy)hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethyl Hexanoate, t-butylperoxyisobutylate, 1,1-bis(t-butylperoxy)cyclohexane, t-hexylperoxyisopropylmonocarbonate, t-butylperoxy-3,5,5 -Trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di(m-toluylperoxy)hexane, t-butylperoxyisopropylmonocarbonate, t- Butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, t-butylperoxyacetate, etc. are mentioned. It is possible to suitably use the compound described in International Publication No. 2009/063827, for example, as a curing agent that generates free radicals by heating other than the peroxyester. These are used individually by 1 type or in combination of 2 or more types.

These curing agents may be used alone or in combination of two or more, and may further be used in combination with a decomposition accelerator, decomposition inhibitor, or the like. Alternatively, these curing agents may be coated with a polyurethane-based or polyester-based high molecular substance or the like to form microencapsulation. A microencapsulated curing agent is preferable because the pot life is extended.

As the photocurable adhesive composition, a composition containing the same epoxy resin or radically polymerizable substance used in the thermosetting adhesive composition described above and a photoinitiator is exemplified.

The blending amount of the adhesive composition may be 70 to 99.9 parts by volume, 75 to 99.75 parts by volume, or 80 to 99.5 parts by volume when the total volume of the conductive adhesive is 100 parts by volume. When the compounding amount of the adhesive composition is in the above range, when the conductive adhesive of the present embodiment is used as a circuit connection material, the gap between the electrodes is maintained at the time of circuit connection and after connection, and the required strength and elastic modulus are provided to provide excellent connection reliability becomes easier to obtain.

If necessary, the adhesive composition according to the present embodiment may be used by adding a film forming material. A film-forming material, when a liquid material is solidified to form a constituent composition into a film, facilitates handling of the film under normal conditions (normal temperature and normal pressure), and does not easily tear, crack, or become sticky. It is to impart mechanical properties and the like to the film. Examples of the film forming material include phenoxy resin, polyvinyl formal resin, polystyrene resin, polyvinyl butyral resin, polyester resin, polyamide resin, xylene resin, polyurethane resin and the like. Among these, phenoxy resins are preferable in view of excellent adhesiveness, compatibility, heat resistance and mechanical strength.

The phenoxy resin is a resin obtained by reacting bifunctional phenols and epihalohydrin until they are polymerized, or by poly-addition of a bifunctional epoxy resin and bifunctional phenols. The phenoxy resin can be obtained, for example, by reacting 1 mole of bifunctional phenols with 0.985 to 1.015 moles of epihalohydrin in a non-reactive solvent in the presence of a catalyst such as an alkali metal hydroxide at a temperature of 40 to 120 ° C. . Further, as the phenoxy resin, from the viewpoint of the mechanical properties and thermal properties of the resin, in particular, the compounding equivalent ratio of the bifunctional epoxy resin and the bifunctional phenol is epoxy group/phenol hydroxyl group = 1/0.9 to 1/1.1, and an alkali metal In the presence of catalysts such as compounds, organic phosphorus compounds, and cyclic amine compounds, in organic solvents such as amides, ethers, ketones, lactones, and alcohols having a boiling point of 120 ° C. or higher, the reaction solid content is 50% by mass or less. It is preferably obtained by heating to 50 ~ 200 ° C. and reacting with the middle part. You may use a phenoxy resin individually or in mixture of 2 or more types.

As said bifunctional epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy resin, biphenyl diglycidyl ether, methyl substituted biphenyl diglycidyl ether etc. can be mentioned. Bifunctional phenols have two phenolic hydroxyl groups. Bifunctional phenols include, for example, hydroquinones, bisphenol A, bisphenol F, bisphenol AD, bisphenol S, bisphenol fluorene, methyl-substituted bisphenol fluorene, dihydroxybiphenyl, methyl-substituted dihydroxybiphenyl, etc. Bisphenols etc. are mentioned. The phenoxy resin may be modified (for example, epoxy modified) with a radically polymerizable functional group or other reactive compound.

The blending amount of the film forming material may be 10 to 90 parts by mass or 20 to 60 parts by mass, based on the total mass of the conductive adhesive being 100 parts by mass.

The adhesive composition according to the present embodiment may further contain a polymer or copolymer having at least one of acrylic acid, acrylic acid ester, methacrylic acid ester, and acrylonitrile as a monomer component. Here, from the viewpoint of excellent stress relaxation, the adhesive composition includes a copolymer-based acrylic rubber containing glycidyl acrylate and/or glycidyl methacrylate containing a glycidyl ether group in combination. desirable. The weight average molecular weight of these acrylic rubbers may be 200,000 or more from the viewpoint of enhancing the cohesive force of the adhesive composition.

The adhesive composition according to the present embodiment may further contain rubber fine particles, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents, phenol resins, melamine resins, isocyanates, and the like. there is.

It is preferable that the rubber fine particles have an average particle diameter of 2 times or less of the average particle diameter of the conductive particles to be blended, and that the storage modulus at room temperature (25°C) is 1/2 or less of the storage modulus of the conductive adhesive at room temperature. Do. In particular, when the material of the rubber microparticles is silicone, acrylic emulsion, SBR, NBR or polybutadiene rubber, it is suitable to use them alone or in a mixture of two or more. These three-dimensionally crosslinked rubber fine particles have excellent solvent resistance and are easily dispersed in the adhesive composition.

The filler can improve connection reliability and the like of electrical characteristics between circuit electrodes when the conductive adhesive of the present embodiment is used as a circuit connection material. As the filler, a filler having an average particle diameter of, for example, 1/2 or less of the average particle diameter of the conductive particles can be suitably used. Moreover, when using together nonconductive particle|grains, if it is less than the average particle diameter of nonconductive particle|grains, it can be used.

The compounding amount of the filler may be 5 to 60 parts by mass with respect to 100 parts by mass of the conductive adhesive. When the compounding amount is 60 parts by mass or less, the connection reliability improving effect tends to be more sufficiently obtained, and on the other hand, when the amount is 5 parts by mass or more, the effect of adding a filler tends to be sufficiently obtained.

As the coupling agent, a compound containing an amino group, a vinyl group, an acryloyl group, an epoxy group or an isocyanate group is preferable because adhesiveness is improved.

The conductive adhesive of this embodiment can be suitably used as a circuit connection material. The circuit connection material melts and flows at the time of connection to obtain a connection of phase-opposed circuit electrodes, and then cures to maintain the connection, and the fluidity of the circuit connection material is an important factor. As an index showing this, the following are mentioned, for example. That is, when a circuit connecting material of 5 mm × 5 mm with a thickness of 35 μm is sandwiched between two glass plates of 15 mm × 15 mm with a thickness of 0.7 mm, and heating and pressing are performed under the conditions of 170 ° C., 2 MPa, and 10 seconds, before heating and pressing The value of fluidity (B)/(A) expressed by using the area (A) of the main surface of the circuit connecting material and the area (B) of the main surface after heating and pressing may be 1.3 to 3.0 or 1.5 to 2.5. . When it is 1.3 or more, the fluidity is suitable, and a good connection tends to be easily obtained, and when it is 3.0 or less, bubbles are less likely to occur and reliability tends to be excellent.

When using the conductive adhesive of this embodiment as a circuit connection material, the elastic modulus at 40 degreeC after hardening of a conductive adhesive may be 100-3000 Mpa, and may be 200-2000 Mpa. The modulus of elasticity of the conductive adhesive after curing can be measured using, for example, a dynamic viscoelasticity measuring device (DVE, DMA, etc.).

When the conductive adhesive of the present embodiment is used as a circuit connection material, the circuit connection material is used for connection between circuit electrodes, FOG (Flex on Glass) connection, FOF (Flex on Flex) connection, FOP (Flex on Polymer) Suitable for connection, etc. Here, FOG connection is a method of connecting a flexible substrate and an organic EL panel or LCD panel represented by, for example, TCP, COF, and FPC, and constitutes a circuit electrode formed on a flexible substrate and an organic EL panel or LCD panel. It refers to the connection of circuit electrodes formed on a glass substrate. Further, FOF connection refers to a connection between a circuit electrode formed on a flexible substrate and a circuit electrode formed on the flexible substrate, and FOP connection refers to a circuit electrode formed on a flexible substrate and a circuit electrode formed on a polymer substrate constituting an organic EL panel or LCD panel. refers to the connection of

In addition, the conductive adhesive of this embodiment can also be formed in the form of a film. Specifically, a conductive adhesive-containing liquid containing an adhesive composition and conductive particles is prepared by dissolving each of the above-described predetermined components in an organic solvent or the like, and using a coating device on a film made of polyethylene terephthalate (PET) or the like Then, a film-like conductive adhesive can be obtained by further applying a predetermined drying treatment. Such a conductive adhesive may have a thickness of 3 to 100 μm or 5 to 50 μm. When using a film-like conductive adhesive having such a thickness as a circuit connection material, it becomes easy to ensure suitable circuit connection and handling properties.

The conductive adhesive of this embodiment can be used as a circuit connecting material such as an anisotropic conductive adhesive.

<circuit connection structure>

The circuit connection structure of the present embodiment is described above, interposed between a first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and the first circuit member and the second circuit member. It has a connecting portion made of a cured product of the conductive adhesive of the present embodiment.

In this embodiment, as the material of the circuit electrode, Ti, Al, Mo, Co, Cu, Cr, Sn, Zn, Ga, In, Ni, Au, Ag, V, Sb, Bi, Re, Ta, Nb, W etc. can be used, but at least one of the 1st circuit electrode and the 2nd circuit electrode may equip the surface with the layer containing Ti. As such an electrode, for example, an electrode provided with an Al layer and a layer containing Ti in this order from the substrate side, a Ti layer, an electrode provided with an Al layer and a layer containing Ti in this order, a Mo layer, An electrode including an Al layer and a layer containing Ti in this order, an electrode including an AlNd layer and a layer containing Ti in this order, and the like are exemplified.

Here, the layer containing Ti may be a layer containing at least Ti as a constituent element, a layer containing Ti as a main component, or a layer containing Ti alone (a layer made of Ti). . Here, "main component" refers to a component contained at 40 atm% or more with respect to all constituent elements. However, from the viewpoint of sufficiently exhibiting the characteristics of the circuit connection material described above, the layer containing Ti may be a layer containing at least 50 atm% of Ti or a layer containing 100 atm% of Ti (a layer made of Ti).

The thickness of the circuit electrode may be 100 to 5000 nm or 100 to 2500 nm from the viewpoint of balancing connection resistance and price. Moreover, the lower limit can also be made into 500 nm. On the other hand, the thickness of the layer containing Ti may be about 5 to 2000 nm from the viewpoint of sufficiently securing corrosion resistance, chemical stability, physical stability, gas barrier properties and diffusion barrier properties.

In the circuit connection structure of the present embodiment, a first circuit member having a first circuit electrode and a second circuit member having a second circuit electrode are disposed so that the first circuit electrode and the second circuit electrode face each other, and are disposed facing each other. The conductive adhesive of the present embodiment is interposed between the first circuit electrode and the second circuit electrode, and the first circuit member and the second circuit member are thermally compressed to electrically connect the first circuit electrode and the second circuit electrode. By doing so, it can be produced. Thus, the circuit connecting material comprising the conductive adhesive of the present embodiment is useful as a material for bonding electric circuits to each other.

More specifically, as a circuit member, board|substrates, such as chip components, such as a semiconductor chip, a resistor chip, and a capacitor chip, and a printed circuit board, etc. are mentioned, for example. In such a circuit member, a plurality of circuit electrodes described above are usually provided (a single number may be used in some cases). At least a part of these circuit electrodes are arranged to face each other, and the circuit connecting material made of the conductive adhesive of the present embodiment is interposed between the facing circuit electrodes, and at least one set of circuit members is heated and pressurized so that the facing circuit electrodes are placed together. electrically connected to At this time, circuit electrodes disposed facing each other are electrically connected via conductive particles included in the conductive adhesive, while insulation between adjacent circuit electrodes is maintained. In this way, the circuit connection material made of the conductive adhesive of the present embodiment exhibits anisotropic conductivity.

Next, one Embodiment of the manufacturing method of a circuit connection structure is described using FIG. 3. FIG. Fig. 3 is a process cross-sectional view schematically showing a manufacturing method of a circuit connection structure according to an embodiment of the present invention. Fig. 3 (a) is a cross-sectional view of a process before connecting circuit members to each other, Fig. 3 (b) is a cross-sectional view of a process when circuit members are connected to each other, and Fig. 3 (c) is a cross-sectional view of a process after connecting circuit members to each other. section of the process.

First, as shown in Fig. 3(a), a circuit member provided with circuit electrodes 2 and circuit board 4 on organic EL panel 3, and circuit electrode 6 on circuit board 5 This prepared circuit member is prepared. And on the circuit electrode 2, the film-form circuit connection material 1 is mounted. The film-shaped circuit connection material 1 is made of the conductive adhesive of the present embodiment molded into a film shape.

Next, as shown in Fig. 3(b), while positioning the circuit board 5 provided with the circuit electrode 6 so that the circuit electrode 2 and the circuit electrode 6 face each other, the film image It is mounted on the circuit connection material 1, and the film-like circuit connection material 1 is interposed between the circuit electrode 2 and the circuit electrode 6. Further, the circuit electrodes 2 and 6 have a structure in which a plurality of electrodes are arranged in a depth direction (not shown), and the circuit electrode 2 has a layer containing Ti on the surface (not shown). not).

Since the circuit connection material 1 in this figure is film-like, it is easy to handle. For this reason, this film-shaped circuit connection material 1 can be easily interposed between the circuit electrode 2 and the circuit electrode 6, and the connection operation between the organic EL panel 3 and the circuit board 5 can be performed. can be done easily

Next, while heating, the film-shaped circuit connection material 1 is pressed in the direction of arrow A in Fig. 3(b) through the organic EL panel 3 and the circuit board 5 to perform a curing treatment. Thereby, the circuit connection structure 20 to which circuit members were connected via the hardened|cured material 11 of circuit connection material as shown to FIG.3(c) is obtained. As a method of curing treatment, one or both of heating and light irradiation can be employed depending on the adhesive composition to be used.

In the manufacturing method of the circuit connection structure of the present embodiment, a circuit connection material made of the conductive adhesive of the present embodiment having heat or light curability is one of which the surface is a metal selected from gold, silver, tin, and the platinum group. After forming on the electrode circuit, the other circuit electrode whose surface is titanium is aligned, and these can be heated and pressurized and connected.

Example

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

(Preparation of conductive particles)

Six types of conductive particles shown in Table 1 below were prepared. These particles are core-shell particles in which a plastic particle is used as a core and a metal layer of Ni as a main component covering the plastic particle is used as a shell. Also, No. The average particle diameter of the conductive particles 1 to 6 is 3 μm.

[Table 1]

<Measurement of 20% Compression Hardness of Conductive Particles>

The compression hardness of the conductive particles was determined in the following procedure.

A micro compression tester (device name: Fischer HM2000, manufactured by Fischer Instruments) was prepared, and conductive particles were placed on a slide glass (product name: S1214, manufactured by Matsunami Glass Kogyo Co., Ltd.) on a stage set at a predetermined temperature (25 ° C, 150 ° C). sprayed And, when one particle is selected from among them and compressed at a rate of 0.33 mN/sec from the center with an initial load of 0.1 mN using a prismatic diamond indenter having a square bottom surface of 50 μm on one side, Stress-strain curves were obtained. The 20% compression hardness K value (20%) of the conductive particles was calculated from the following formula.

K value (20%)=(3/√2)×F _20× S ₂₀ ^-3/2× R ^-1/2× 10 ^-3

R: Radius of conductive particle (μm), S ₂₀ : Displacement at 20% strain, F ₂₀ : Load at 20% strain (N)

<Measurement of Compression Recovery Rate of Conductive Particles>

The compression recovery rate of the conductive particles was determined in the following procedure.

A micro compression tester (apparatus name: Fischer HM2000, manufactured by Fisher Instruments) was prepared, and conductive particles were sprayed onto a slide glass (product name: S1214, manufactured by Matsunami Glass Kogyo Co., Ltd.) on a stage set at 25°C. Then, one particle is selected from among them, and a load of 5 mN is applied at a rate of 0.33 mN/sec from the center with an initial load of 0.1 mN using a prismatic diamond indenter having a square bottom surface of 50 μm on one side. The relationship between the load value and compression displacement was measured in the process of reducing the load to the value of the initial load at a rate of 0.33 mN/sec. At this time, when L2 is the displacement from the initial load (load 0.1 mN) to the load reversal (load 5 mN), and the displacement from the load reversal to the final load (load 0.1 mN) is L1, L1/ The value of L2 × 100 (%) was calculated. This operation was performed on 10 conductive particles, and the average value of these was taken as the compression recovery factor.

<Preparation of adhesive composition containing liquid>

(Preparation Example A)

A phenoxy resin was synthesized from a bisphenol A type epoxy resin and a phenolic compound having a fluorene ring structure in the molecule (4,4'-(9-fluorenylidene)-diphenyl), and the resin was mixed with toluene and ethyl acetate. was dissolved in a mixed solution (toluene/ethyl acetate = 50/50 (mass ratio)) to obtain a solution having a solid content of 40% by mass.

On the other hand, acrylic rubber (40 parts by weight of butyl acrylate - 30 parts by weight of ethyl acrylate - 30 parts by weight of acrylonitrile - 3 parts by weight of glycidyl methacrylate copolymer, weight average molecular weight of 800,000) was prepared as a rubber component. Then, this acrylic rubber was dissolved in a mixed solution of toluene and ethyl acetate (toluene/ethyl acetate = 50/50 (mass ratio)) to obtain a solution having a solid content of 15% by mass. In addition, a liquid curing agent-containing epoxy resin (epoxy equivalent: 202) was prepared.

The materials prepared above were blended in a ratio of 20 g/30 g/50 g of phenoxy resin/acrylic rubber/curing agent-containing epoxy resin in terms of solid mass to prepare adhesive composition-containing liquid A.

(Preparation Example B)

50 g of phenoxy resin (product name: PKHC, manufactured by Union Carbide Co., Ltd., weight average molecular weight: 5000) was dissolved in a mixed solvent of toluene/ethyl acetate = 50/50 (mass ratio) to obtain a phenoxy resin solution having a solid content of 40% by mass. .

On the other hand, 400 parts by mass of polycaprolactonediol having a weight average molecular weight of 800, 131 parts by mass of 2-hydroxypropyl acrylate, 0.5 parts by mass of dibutyltin dilaurate as a catalyst, and 1.0 parts by mass of hydroquinone monomethyl ether as a polymerization inhibitor While stirring the mass part, it was heated and mixed at 50 degreeC. Then, 222 mass parts of isophorone diisocyanate was dripped at this liquid mixture, and it heated up at 80 degreeC, further stirring, and carried out the urethane-ized reaction. After confirming that the reaction rate of the isocyanate group became 99% or more, the reaction temperature was lowered to obtain urethane acrylate.

Then, the phenoxy resin solution weighed so that 50 g of solid content was included in the phenoxy resin solution, 30 g of the urethane acrylate, and 15 g of isocyanurate type acrylate (product name: M-215, manufactured by Toagosei Co., Ltd.) and 1 g of phosphate ester type acrylate (product name: P-1M, manufactured by Kyoeisha Chemical Co., Ltd.) and 4 g of benzoyl peroxide (product name: Nyper BMT-K40, manufactured by Nichiyu Co., Ltd.) as a free radical generator, Adhesive composition containing liquid B was prepared.

<Production of Circuit Connection Material>

(Example 1)

With respect to 100 parts by mass of the adhesive composition-containing liquid A obtained above, No. 10 parts by mass of the conductive particles of No. 1 were dispersed to prepare a liquid containing a circuit connection material. This circuit connection material-containing solution was applied onto a polyethylene terephthalate (PET) film having a thickness of 50 μm, one side of which was surface-treated, using a coating device, and dried in hot air at 70° C. for 3 minutes to form a PET film having a thickness of 20 μm. A film-like circuit connection material was obtained. When the total mass of the obtained circuit connection material was 100 parts by volume, the contents of the adhesive composition and the conductive particles were 94 parts by volume and 6 parts by volume, respectively.

(Examples 2-3 and Comparative Examples 1-3)

A film-shaped circuit connection material was produced in the same manner as in Example 1 except that the type of conductive particle was changed as shown in Table 2.

(Example 4)

With respect to 100 parts by mass of the adhesive composition-containing liquid B obtained above, No. 10 parts by mass of the conductive particles of No. 1 were dispersed to prepare a liquid containing a circuit connection material. This circuit connection material-containing liquid is coated on a PET film with a thickness of 50 μm, one side of which is surface-treated, using a coating device, and dried with hot air at 70° C. for 3 minutes, thereby forming a circuit connection material in the form of a film with a thickness of 20 μm on the PET film. got When the total volume of the obtained circuit connection material was 100 parts by volume, the contents of the adhesive composition and the conductive particles were 94 parts by volume and 6 parts by volume, respectively.

(Examples 5-6 and Comparative Examples 4-6)

A film-shaped circuit connection material was produced in the same manner as in Example 4, except that the type of conductive particle was changed as shown in Table 2.

<Evaluation of connection reliability>

The film-shaped circuit connection material with PET film, obtained in Examples and Comparative Examples, was cut into a predetermined size (1.5 mm wide, 3 cm long), and the adhesive surface was cut with titanium (film thickness 50 nm) and aluminum from the outermost surface. (Film thickness: 250 nm) was transferred onto a coated glass substrate (thickness: 0.7 mm) at 70°C and 1 MPa for 2 seconds, and the PET film was peeled off. Next, a flexible circuit board (FPC) having 800 tin-plated copper circuits with a pitch of 25 μm and a thickness of 8 μm is placed on the transferred circuit connection material, and pressurized at 24° C. and 0.5 MPa for 1 second to cut the FPC on the glass substrate. decided Next, this was installed in the main crimping device, a 200 μm thick silicone rubber sheet was used as a cushioning material, and from the FPC side, it was heated and pressed at 170° C. and 4.5 MPa for 6 seconds with a heat tool, and connected over a width of 1.5 mm to connect the circuit. got a struct. The resistance value between adjacent circuits of the FPC including the connection portion of this circuit connection structure was measured with a multimeter (device name: TR6845, manufactured by Advantest Co., Ltd.). Moreover, 32 points of resistance between adjacent circuits were measured, the average value was calculated|required, and this was made into the initial connection resistance. Moreover, the member after a measurement was processed under the conditions of 85 degreeC and 85 %RH for 250 hours, and the connection resistance after the high-temperature, high-humidity process was similarly measured. At this time, the resistance increase rate from the initial connection resistance was combined and calculated. The obtained results are shown in Table 2.

[Table 2]

As shown in Table 2, the circuit connection materials obtained in Examples show lower resistance than the circuit connection materials obtained in Comparative Examples, and the increase in connection resistance is small even after high-temperature, high-humidity treatment, and connection reliability is excellent. .

One… circuit connection material
2, 6... circuit electrode
3... organic EL panel
4, 5... circuit board
11... Cured product of circuit connection material
20... circuit connection structure

Claims (8)

An adhesive composition and conductive particles are contained,
A conductive adhesive having a compression hardness of the conductive particles at 20% compression of 10.0 GPa or more at 25°C and 3.5 GPa or less at 150°C. The method of claim 1,
A conductive adhesive having a compression recovery rate of the conductive particles at 25°C of 50 to 75%. According to claim 1 or claim 2,
The conductive adhesive, wherein the average particle diameter of the conductive particles is 2 μm or more and 10 μm or less. The method according to any one of claims 1 to 3,
It is used for connecting circuit electrodes,
The conductive adhesive, wherein the connection is a Flex on Glass connection, a Flex on Flex connection, or a Flex on Polymer connection. Between a first circuit member having a first circuit electrode and a second circuit member having a second circuit electrode, the conductive adhesive according to any one of claims 1 to 4 is interposed between the first circuit member and the second circuit member. A method for manufacturing a circuit connection structure comprising a step of thermally compressing a second circuit member to electrically connect the first circuit electrode and the second circuit electrode. The method of claim 5,
The manufacturing method of the circuit connection structure in which at least one of the said 1st circuit electrode and the said 2nd circuit electrode has a layer containing Ti on the surface. A first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and a connection portion interposed between the first circuit member and the second circuit member,
The circuit connection structure in which the said connection part is a hardened|cured material of the conductive adhesive of any one of Claims 1-4. The method of claim 7,
The circuit connection structure in which at least one of the said 1st circuit electrode and the said 2nd circuit electrode has a layer containing Ti on the surface.

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