Conductive resin composition, conductive adhesive, cured product, semiconductor device

Abstract

To provide a conductive resin composition which is useful as a conductive material for a flexible hybrid electronics field, especially, a conductive connection material for a wearable application and an electronic shelf label, is a low temperature drying type, and has high flexibility.SOLUTION: A conductive resin composition contains (A) a thermoplastic resin having a ratio (hard segment: soft segment) of a hard segment to a soft segment of 1:99 to 50:50, and has a weight average molecular weight of 25,000 or more, (B) an organic solvent having a boiling point of 155-205°C, and (C) conductive particles.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a conductive resin composition used in the field of flexible hybrid electronics (hereinafter referred to as FHE).

Background Art

[0002] In recent years, attention has been increasing on wearable applications using the Internet, and development of applications in the FHE field such as biosensors has been carried out mainly in the sports and healthcare fields.

[0003] As wearable applications, development aimed at wearing on the human body such as wristbands, clothes, and glasses has been promoted, and materials that can cope with bending and stretching on the human body surface are required.

[0004] In these applications, when imparting an electrical function to everything, mounting of sensors, capacitors, processors, memories, etc. is required together with the formation of wiring. In the FHE field, since semiconductors such as processors and memories mounted on these flexible wiring boards cannot be made extensible, a low-elastic conductive adhesive for mounting these semiconductors on a flexible wiring substrate is required.

[0005] As the conductive adhesive, for example, Patent Document 1 below discloses a curable resin composition characterized by containing '(A) a polyimide silicone resin having two or more phenolic hydroxyl groups in one molecule, (B) an epoxy resin, and (C) a conductive metal powder'.

[0006] Patent Document 2 below discloses a conductive resin composition characterized by containing '(A) an epoxy resin, (B) a compound having a (meth)acryloyl group and a glycidyl group, (C) a phenolic resin-based curing agent, (D) a radical polymerization initiator, and (E) conductive particles'.

[0007] Patent Document 3 below discloses a “(A) formula: -R 1 -O- [wherein R 1 is a hydrocarbon group having 1 to 10 carbon atoms.] A polyether polymer having a main chain having a repeating unit represented by and a terminal group which is a hydrolyzable silyl group, and a “(B) conductive adhesive containing silver particles”.

[0008] Patent Document 4 below discloses a “conductive adhesive containing conductive powder, a thermosetting silicone resin, and a solvent”.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, the curable resin composition of Patent Document 1 above is not low in elasticity, that is, it has no flexibility, so there is a risk of peeling, cracking, etc. when used as an adhesive. In addition, the conductive resin composition of Patent Document 2 above also has a high elastic modulus of the cured product and is not suitable for the FHE field. As described above, the conventional connection materials have a high elastic modulus of the cured product. For example, when applied to an application that needs to follow the movement of a person such as a wearable application, the parts may fall off because they cannot follow the movement of the human body, or the movement of the person itself may be hindered.

[0011] In addition, when imparting an electrical function to a wearable application, since the base material used is a heat-sensitive material such as plastic or thermoplastic polyurethane (TPU), with the conventional connection method using solder or a thermosetting epoxy resin-based conductive adhesive, it cannot withstand the temperature of the solder melting point or the curing temperature of the conductive adhesive, and there is a possibility that the base material itself will be damaged. Although the conductive adhesive of Patent Document 3 above has flexibility, it has problems such as a high curing temperature (about 185°C) and a high resistance value. Also, the conductive adhesive of Patent Document 4 above has problems such as a high curing temperature (200°C × 60 minutes) and a high resistance value.

[0012] Therefore, as a conductive connection material for applications in the FHE field, two points are important: having flexibility / stretchability (flexible / stretchable) and being processable at low temperatures.

[0013] In particular, for wearable applications, which are one of the applications in the FHE field, stretchability is required, and a conductive connection material having stretchability is required to follow the stretching.

[0014] On the other hand, as one of the applications in the FHE field, ESL (Electrical Shelf Label) can also be mentioned. Since one of the usage modes of ESL assumes a usage mode in which the base material is curved, flexibility is also required for the conductive connection material. Furthermore, as a conductive connection material for the FHE field, for example, for ESL, since the base material used is a heat-sensitive material such as plastic or thermoplastic polyurethane (TPU), it is required to dry and cure at a low temperature of 70°C or less.

[0015] Therefore, in view of the above problems, an object of the present invention is to provide a low-temperature drying type conductive resin composition that is useful as a conductive material for the FHE field, particularly a conductive connection material for wearable applications and ESL, and has high stretchability.

Means for Solving the Problems

[0016] A conductive resin composition according to one embodiment of the present invention comprises: (A) a thermoplastic resin having a ratio of hard segment to soft segment (hard segment: soft segment) of 1:99 to 50:50 and a weight average molecular weight of 25,000 or more; (B) an organic solvent having a boiling point of 155°C to 205°C; and (C) conductive particles.

[0017] In the conductive resin composition of the above embodiment, it is preferable that (A) the thermoplastic resin is at least one selected from polystyrene resins, polyolefin resins, polyvinyl chloride resins, polyurethane resins, polyester resins, polyamide resins, polybutadiene resins, hydrides thereof, and modified copolymer hydrides obtained by modifying the hydrides.

[0018] In the conductive resin composition of the above embodiment, it is preferable that the mass ratio of (C) conductive particles to (A) thermoplastic resin ((C):(A)) is 95:5 to 80:20.

[0019] In the conductive resin composition of the above embodiment, it is preferable that the average particle diameter (D50) of (C) conductive particles is 1 μm to 25 μm.

[0020] In the conductive resin composition of the above embodiment, it is preferable that (C) the conductive particles include silver particles having a surface treatment.

[0021] In the conductive resin composition of the above embodiment, it is preferable that the ratio of the Igros value to the BET value of (C) conductive particles (Igros value / BET value) is 1.2 or more.

[0022] In the conductive resin composition of the above embodiment, it is preferable to further include (D) a dispersant.

[0023] In the conductive resin composition of the above embodiment, it is preferable that the viscosity at 25°C and 10 rpm measured with a rotational viscometer is 40 Pa·s to 200 Pa·s.

[0024] When the conductive resin composition of the above form is dried and cured under heating conditions of 70°C for 30 minutes, the elongation rate of the cured product at room temperature is preferably 70% or more, and the specific resistance value of the cured product is preferably 10×10 -3 Ω·cm or less, and the residual solvent amount of the cured product is preferably 25 parts by mass or less based on the total amount of the resin composition.

[0025] The conductive resin composition of the above form is suitable for FHE applications.

[0026] The conductive resin composition of the above form is preferably included in a conductive adhesive, or preferably cured to form a cured product.

[0027] It is preferable to provide a cured product of the conductive resin composition of the above form in a semiconductor device. Further, this cured product can be laminated on a substrate to form a laminated structure. This laminated structure is preferably used for electronic components.

[0028] According to the present invention, it is possible to provide a conductive resin composition that is useful as a conductive material for the FHE field, particularly a low-temperature drying type and highly stretchable conductive material for wearable applications and ESL.

Brief Description of the Drawings

[0029]

Figure 1

Embodiments for Carrying Out the Invention

[0030] Hereinafter, a conductive resin composition according to an embodiment of the present invention will be described. However, the present invention is not limited to this embodiment.

[0031] <Conductive Resin Composition> The conductive resin composition of one embodiment of the present invention (hereinafter referred to as this conductive resin composition) comprises: (A) a thermoplastic resin having a ratio of hard segment to soft segment (hard segment: soft segment) of 1:99 to 50:50 and a weight average molecular weight of 25,000 or more, (B) an organic solvent having a boiling point of 155°C to 205°C, and (C) conductive particles.

[0032] <(A) Thermoplastic resin> (A) The thermoplastic resin preferably has a ratio of hard segment to soft segment (hard segment: soft segment) of 1:99 to 50:50. By setting it within this range, appropriate flexibility can be imparted to this conductive resin composition. From such a viewpoint, the hard segment: soft segment is more preferably 10:90 to 45:55, and even more preferably 30:70 to 40:60.

[0033] In the present invention, the hard segment is the rigid part in (A) the thermoplastic resin, indicating a high glass transition temperature (Tg) segment. The soft segment is the flexible part in (A) the thermoplastic resin, indicating a low glass transition temperature (Tg) segment. In particular, a block copolymer of a hard segment having a glass transition temperature (Tg) of less than 150°C and a soft segment having a glass transition temperature (Tg) of less than 0°C is more suitable. The glass transition point Tg is measured by differential scanning calorimetry (DSC). In addition, the glass transition temperature (Tg) of the whole (A) thermoplastic resin is preferably -60°C to 120°C, more preferably -50°C to 100°C, and even more preferably -40°C to 80°C. By setting it within this range, appropriate flexibility can be imparted to this conductive resin composition.

[0034] (A) The thermoplastic resin is not particularly limited as long as it has a hard segment and a soft segment. For example, at least one selected from polystyrene resins, polyolefin resins, polyvinyl chloride resins, polyurethane resins, polyester resins, polyamide resins, polybutadiene resins, hydrides thereof, and modified copolymer hydrides obtained by modifying the hydrides may be used, and two or more thereof may be used in combination.

[0035] More specifically, examples of the polystyrene resin include those using polybutadiene, polyisoprene, etc. for the soft segment and polystyrene for the hard segment. Examples of the polyolefin resin include those using ethylene-propylene rubber for the soft segment and polypropylene for the hard segment. Examples of the polyvinyl chloride resin include those using polyvinyl chloride for both the soft segment and the hard segment. Examples of the polyurethane resin include those using polyether or polyester for the soft segment and polyurethane for the hard segment. Examples of the polyester resin include those using polyether for the soft segment and polyester for the hard segment. Examples of the polyamide resin include those using polypropylene glycol, polytetramethylene ether glycol, polyester, or polyether for the soft segment and polyamide (nylon resin) for the hard segment. Examples of the polybutadiene resin include those using amorphous butyl rubber for the soft segment and syndiotactic 1,2-polybutadiene resin for the hard segment. These hydrides, modified copolymer hydrides obtained by modifying the hydrides, etc. may also be used.

[0036] (A) The thermoplastic resin preferably contains a polyurethane resin or a polyester resin as a main component. Here, the main component refers to the component blended in the largest proportion in the (A) thermoplastic resin. Specifically, it preferably refers to 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more (including 100% by mass).

[0037] (A) The thermoplastic resin preferably has a weight average molecular weight of 25,000 or more. When the molecular weight of the thermoplastic resin is too low, there is a problem that the flexibility of this conductive resin composition becomes low, which is not preferable. On the other hand, when the molecular weight of the thermoplastic resin is too high, it becomes necessary to increase the blending amount of the solvent to achieve a predetermined viscosity. When the blending amount of the solvent increases, there may be a problem that the film thickness of the coating film becomes thin. Therefore, when the molecular weight of the (A) thermoplastic resin is within the above range, the viscosity, elongation characteristics, and electrical resistance value of the cured product can be made appropriately balanced. From such a viewpoint, the weight average molecular weight of the (A) thermoplastic resin is more preferably 25,000 or more, even more preferably 30,000 or more, and particularly preferably 34,000 or more. The upper limit is not particularly limited, but it is preferably 300,000 or less, more preferably 250,000 or less, and even more preferably 200,000 or less.

[0038] Specific examples of the (A) thermoplastic resin include thermoplastic polyurethane elastomer "Milactran (registered trademark)" (manufactured by Nippon Milactran Co., Ltd.), hydrogenated styrene-based thermoplastic elastomer (SEBS) "Tuftec (registered trademark)" (manufactured by Asahi Kasei Corporation), saturated copolymerized polyester resin "Elyther (registered trademark)" (manufactured by Unitika Ltd.), and the like.

[0039] (A) The proportion of the thermoplastic resin is preferably 5 to 20 parts by mass, more preferably 7 to 20 parts by mass, and even more preferably 7 to 18 parts by mass with respect to the total of the (A) thermoplastic resin and the (C) conductive particles. By setting it within this range, a cured product having flexibility / stretchability and a good specific resistance can be obtained.

[0040] <(B) Organic solvent> (B) The organic solvent dissolves the (A) thermoplastic resin and preferably has a boiling point of 155°C to 205°C. By being 155°C or higher, low-temperature drying of this conductive resin composition at 70°C or lower becomes possible while maintaining workability. On the other hand, when it exceeds 205°C, the solvent cannot be sufficiently removed during heating for drying, and there is a possibility that the drying property of the coating film deteriorates. From such a viewpoint, the boiling point of the (B) organic solvent is more preferably 155°C to 190°C, and particularly preferably 155°C to 180°C.

[0041] (B) As the organic solvent, for example, amine solvents, alcohol solvents, ketone solvents, etc. can be used, and two or more kinds can be used in combination.

[0042] More specifically, as amine solvents, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, diisopropylamine, butylamine, isobutylamine, sec-butylamine, tert-butylamine, dibutylamine, diisobutylamine, tributylamine, pentylamine, dipentylamine, tripentylamine, 2-ethylhexylamine, allylamine, aniline, N-methylaniline, ethylenediamine, propylenediamine, diethylenetriamine, formamide, N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide, 2-pyrrolidone, N-methylpyrrolidone, ε-caprolactam, carbamic acid esters, etc. can be mentioned. Examples of alcohol solvents include methanol, ethanol, isopropyl alcohol (IPA), benzyl alcohol, and the like. Examples of ketone solvents include acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone, acetonylacetone, mesityloxide, phorone, isophorone, cyclohexanone, methylcyclohexanone, and the like.

[0043] Specific examples of organic solvents having a boiling point of 155°C to 205°C include Anone (cyclohexanone) (manufactured by Nippon Alcohol Sales Co., Ltd.), DEDG (diethylene glycol diethyl ether) (manufactured by Toho Chemical Industry Co., Ltd.), acetophenone (manufactured by Tokyo Chemical Industry Co., Ltd.), EC (manufactured by Oxalis Chemicals Co., Ltd.), DBE (manufactured by INVISTA), EBA (manufactured by Fujifilm Wako Pure Chemical Corporation), Shellsol MC311 (manufactured by Oxalis Chemicals Co., Ltd.), DIBK (manufactured by Sankyo Chemical Co., Ltd.), butyl cellosolve (manufactured by Daishin Chemical Co., Ltd.), 3-methoxybutyl acetate (manufactured by Daicel Corporation), EEP (manufactured by Sankyo Chemical Co., Ltd.), Solfit (manufactured by Kuraray Co., Ltd.), orthodichlorobenzene (manufactured by Kureha Corporation), and the like.

[0044] (B) The organic solvent is not particularly limited, but with respect to 100 parts by mass of the (A) thermoplastic resin, 100 parts by mass to 700 parts by mass is preferable, 150 parts by mass to 600 parts by mass is more preferable, and 200 parts by mass to 400 parts by mass is even more preferable. By being within this range, the thermoplastic resin can be dissolved well, and an excellent coating film can be formed even by low-temperature drying at 70°C or lower. (B) The organic solvent can be appropriately dissolved by using a weight about 4 times the weight of the (A) thermoplastic resin. In addition, the organic solvent can be appropriately added additionally to the resin composition for adjusting the viscosity of the resin composition.

[0045] <(C) Conductive particles> (C) The conductive particles are used to impart conductivity and / or thermal conductivity to the present conductive resin composition. Although not particularly limited, it is preferable that the electrical conductivity is 106 S / m or more. (C) The conductive particles include not only metal powders but also coated powders. The coated powder is one in which a core (core particle) is coated with a conductive substance. This core may be a non-conductive substance.

[0046] (C) The conductive particles include, for example, gold, silver, nickel, copper, palladium, platinum, bismuth, tin, alloys thereof (particularly, bismuth-tin alloy, solder, etc.), aluminum, indium tin oxide, silver-coated copper, silver-coated aluminum, metal-coated glass spheres, silver-coated fibers, silver-coated resins, antimony-doped tin, tin oxide, carbon fibers, graphite, carbon black, and mixtures thereof. Among them, considering conductivity and thermal conductivity, preferably, at least one metal selected from the group consisting of silver, nickel, copper, tin, aluminum, silver alloys, nickel alloys, copper alloys, tin alloys, and aluminum alloys, more preferably, at least one metal selected from the group consisting of silver, copper, and nickel, still more preferably, silver or copper, and most preferably, silver.

[0047] (C) The shape of the conductive particles is not particularly limited, and may be any of spherical, amorphous, flake-shaped (scaly), filamentous (needle-shaped), dendritic, etc. Here, the flake shape refers to a shape with an aspect ratio of "major axis / minor axis" of 2 or more, including flat plate shapes such as plate-shaped and scaly. The major axis and minor axis of the particles constituting (C) the conductive particles can be determined based on an image obtained from a scanning electron microscope (SEM: Scanning Electron Microscope) (n = 20). The "major axis" refers to the longest diameter among the line segments passing through the approximate center of gravity of the particle in the particle image obtained by SEM, and the "minor axis" refers to the shortest one among the line segments passing through the approximate center of gravity of the particle in the particle image obtained by SEM. Note that the shape of the particles may be a combination of particles having different shapes.

[0048] (C) The conductive particles are not particularly limited, but the tap density is preferably 1.5 g / cm 3 or more, more preferably 2.0 g / cm 3 to 6.0 g / cm 3 . Here, the tap density can be measured in accordance with JIS Z 2512 Metal Powders - Method for Measuring Tap Density. If the tap density is too low, it is difficult to disperse (C) conductive particles at a high density in the cured product of the conductive resin composition, and the conductivity of the cured product tends to decrease. On the other hand, if the tap density is too high, separation and sedimentation of (C) conductive particles are likely to occur in the conductive resin composition.

[0049] (C) The conductive particles preferably have an average particle diameter (D50) of 1 μm to 25 μm. By being within this range, the dispersibility of (C) conductive particles in the conductive resin composition becomes good. From such a viewpoint, it is more preferably 1 μm to 20 μm, and even more preferably 2 μm to 20 μm. Note that the average particle diameter (D50) refers to the particle diameter (median diameter) at which the cumulative frequency in the volume-based particle size distribution measured by the laser diffraction method is 50%.

[0050] (C) The conductive particles preferably contain surface-treated silver particles. By containing surface-treated silver particles, the electrical resistance of the conductive resin composition can be reduced, and the dispersibility of the particles can also be improved. The surface treatment can be performed using a liquid fatty acid, a solid fatty acid, or an aliphatic amine. Examples of the liquid fatty acid include saturated fatty acids such as butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, and unsaturated fatty acids such as myristoleic acid, palmitoleic acid, ricinoleic acid, oleic acid, linoleic acid, and linolenic acid. These fatty acids may be used alone or in combination of two or more. Examples of the solid fatty acids include saturated fatty acids having 10 or more carbon atoms such as capric acid, palmitic acid, and stearic acid, and unsaturated fatty acids such as crotonic acid and sorbic acid. Examples of the aliphatic amines include isobutylamine, octylamine, decylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, 2-ethylhexyloxypropylamine, and 3-lauryl-oxypropylamine. Among them, it is preferable to be surface-treated with stearic acid and oleic acid.

[0051] (C) The conductive particles are not particularly limited, but preferably have a BET value (specific surface area) of 4.0 m 2 / g or less. If the BET value (specific surface area) is too large, the viscosity will increase during pasting, and the handleability will be likely to deteriorate. On the other hand, if the BET value (specific surface area) is too small, the contact area between silver particles will be small, and the conductivity will decrease. From such a viewpoint, it is more preferably 0.1 m 2 / g to 3.0 m 2 / g, and even more preferably 0.1 m 2 / g to 2.0 m 2 / g. The BET value (specific surface area) can be measured by the BET method.

[0052] (C) The conductive particles are not particularly limited, but preferably have an Igros value (loss on ignition) of 0.1% to 3.0%. If the Igros value (loss on ignition) is too small, the dispersibility of the conductive particles will deteriorate. On the other hand, if the Igros value (loss on ignition) is too large, the contact between Ag fillers will deteriorate, and the specific resistance value of the cured product of the present conductive resin composition will deteriorate. From such a viewpoint, it is more preferably 0.15% to 2.0% in terms of the Igros value (loss on ignition), and even more preferably 0.15% to 1.5%. Note that the ignition loss value indicates the amount (mass %) of the surface treatment agent present on the surface of the (C) conductive particles and can be calculated from the mass of the residue after firing the (C) conductive particles at 800 °C for 30 minutes.

[0053] The ratio of the ignition loss value to the BET value (ignition loss value / BET value) of the (C) conductive particles is preferably 1.2 to 6.0. When the ratio of the ignition loss value to the BET value of the (C) conductive particles is small, the amount of the surface treatment agent relative to the specific surface area is small, and the dispersibility of the (C) conductive particles deteriorates. When the dispersibility deteriorates, when dispersing in a low-boiling solvent, the dispersion time becomes long, the residence time becomes long, and the amount of solvent volatilized in the (C) conductive particle dispersion step increases. On the other hand, when the ratio of the ignition loss value to the BET value of the (C) conductive particles is large, the amount of the surface treatment agent relative to the specific surface area is large, the contact between the Ag fillers of the (C) conductive particles deteriorates, and the specific resistance value of the cured product of this conductive resin composition deteriorates. From such a viewpoint, the ratio of the ignition loss value to the BET value is more preferably 1.2 to 5.0, and further preferably 1.3 to 3.0.

[0054] Specific examples of the (C) conductive particles include AGC-GS or AGC-B2 (both manufactured by Fukuda Metal Foil & Powder Co., Ltd.), which are flaky silver powders, and FA618 (manufactured by DOWA Electronics Co., Ltd.), which is a flaky silver powder.

[0055] In this conductive resin composition, the mass ratio ((C):(A)) of the (C) conductive particles to the (A) thermoplastic resin is preferably 80:20 to 95:5. When it is within this range, the conductivity of this conductive resin composition becomes good. From such a viewpoint, the mass ratio ((C):(A)) is more preferably 80:20 to 92:8, and further preferably 82:18 to 92:8.

[0056] <(D) Dispersant> This conductive resin composition may contain a (D) dispersant. (D) As the dispersant, for example, HYPERMER KD-57 (trade name) (manufactured by CRODA), which is an acidic dispersant, can be used.

[0057] <Other components> This conductive resin composition may consist only of the above components (A) to (C) or only of the above components (A) to (D). However, in addition to these, components such as insulating particles, surface treatment agents such as coupling agents, pigments, dyes, plasticizers, defoaming agents, foam-breaking agents, antioxidants, etc. may be contained as necessary.

[0058] <Physical property values> It is preferable that the elongation rate of the cured product at room temperature when this conductive resin composition is dried and cured under heating conditions of 70°C for 30 minutes is 70% or more. The elongation rate of the cured product is more preferably 75% or more, and even more preferably 90% or more. The elongation rate can be adjusted, for example, by the weight average molecular weight of the (A) thermoplastic resin, the ratio of the hard segment to the soft segment, and the mass ratio of the (A) thermoplastic resin to the (C) conductive particles. In the present invention, room temperature preferably means 0°C to 30°C, more preferably 10°C to 25°C.

[0059] It is preferable that the specific resistance value of the cured product when this conductive resin composition is dried and cured under heating conditions of 70°C for 30 minutes is 10×10 -3 Ω·cm or less. The specific resistance value of the cured product is more preferably 5×10 -3 Ω·cm or less, and even more preferably 1×10 -3 Ω·cm or less. The specific resistance value can be adjusted, for example, by the particle shape, specific surface area of the (C) conductive particles, and the mass ratio of the (A) thermoplastic resin to the (C) conductive particles.

[0060] When the conductive resin composition is dried and cured under heating conditions of 70°C for 30 minutes, the amount of residual solvent in the cured product is preferably 25 parts by mass or less with respect to the total amount (100 parts by mass) of the resin composition. More preferably, the amount of residual solvent in the cured product is 20 parts by mass or less with respect to the total amount (100 parts by mass) of the resin composition, and even more preferably 15 parts by mass or less. By making the amount of residual solvent within this range, the specific resistance value of the cured product of this conductive resin composition can be improved. The amount of residual solvent can be adjusted, for example, by the boiling point of the (B) organic solvent, etc. For the cured product of the resin composition, using TGDTA, heat it from 25 to 200°C at a rate of 10°C / min, and take the mass reduction amount at 200°C as the amount of residual solvent.

[0061] It is preferable that the viscosity of this conductive resin composition is 40 Pa·s to 200 Pa·s at 25°C and 10 rpm measured with a rotational viscometer. By setting the viscosity within such a range, the workability of this conductive resin composition can be improved. From such a viewpoint, the viscosity is more preferably 50 Pa·s to 190 Pa·s, and even more preferably 80 Pa·s to 180 Pa·s.

[0062] <Manufacturing method> This conductive resin composition can be produced by blending (A) a thermoplastic resin, (B) an organic solvent, (C) conductive particles, (D) a dispersant as required, and other components, and stirring and mixing them.

[0063] For stirring and mixing these, known apparatuses can be used. For example, they can be mixed by known apparatuses such as a hybrid mixer, a Henschel mixer, a roll mill, and a three-roll mill. These raw materials may be mixed simultaneously, or a part may be mixed first and the rest may be mixed later. The manufacturing method of this conductive resin composition is not particularly limited as long as each material is sufficiently kneaded.

[0064] <Supply method> This conductive resin composition can be supplied by using a jet dispenser, an air dispenser, or the like. Also, known coating methods (such as dip coating, spray coating, bar coater coating, gravure coating, reverse gravure coating, and spin coater coating) and known printing methods (such as lithography, carton printing, metal printing, offset printing, screen printing, gravure printing, flexographic printing, and inkjet printing) can be used.

[0065] <Curing Conditions> This conductive resin composition can be dried and cured, for example, by heating at a temperature of 40°C to 120°C. The heating temperature is , preferably 50°C to 120°C, more preferably 70°C to 100°C. The heating time is, for example, preferably 0.1 hour to 3 hours, more preferably 0.5 hour to 2 hours.

[0066] In this specification, what is obtained by supplying the conductive resin composition to form a predetermined pattern and heating and drying it, for example, at 70°C for 30 minutes, is referred to as a "cured product".

[0067] <Applications> This conductive resin composition has elasticity and is excellent in low-temperature curability at 70°C or lower. From such a viewpoint, for example, it can be used for the FHE field and is useful for wearable applications, ESL, etc. This conductive resin composition can be included in an adhesive to be used as a conductive adhesive, or can be used as it is or as a cured product obtained by curing it with other components included. The cured product includes the cured product of the conductive adhesive. This cured product can be provided in semiconductor devices such as sensors, capacitors, processors, and memories, or laminated on a substrate such as an inorganic or organic substrate used for an electric circuit board, etc., to form a laminated structure. This laminated structure can be used for ESL, etc.

Examples

[0068] Hereinafter, a conductive resin composition according to an embodiment of the present invention will be described. However, the present invention is not limited to this embodiment.

[0069] In producing the conductive resin compositions of the examples and comparative examples, the following materials were used. H / S represents the ratio of the hard segment to the soft segment (hard segment / soft segment). <Material> 1. (A) Thermoplastic resin (A1) Urethane resin (Product number: P22SRAT, Nippon Miraclan Co., Ltd.) H / S = 34 / 66, weight average molecular weight Mw 120,000 to 180,000 Glass transition temperature (Tg): -40 °C (A2) SEBS (Product number: H1221, Asahi Kasei Corporation) H / S = 12 / 88, weight average molecular weight Mw 147,600 Glass transition temperature (Tg): -25 °C (A3) Polyester resin (Product number: UE-3510, Unitika Ltd.) H / S = 50 / 50, weight average molecular weight Mw 34,000 Glass transition temperature (Tg): -25 °C (A4) Polyester resin (Product number: UE-3400, Unitika Ltd.) H / S = 35 / 65, weight average molecular weight Mw 25,000 Glass transition temperature (Tg): -20 °C (A5) Polyester resin (Product number: UE-3220, Unitika Ltd.) H / S = 35 / 65, weight average molecular weight Mw 25,000 Glass transition temperature (Tg): 5 °C (A6) Polyamide resin (Product number: PA66-1, Asahi Kasei Corporation) H / S = 77.45 / 22.55, weight average molecular weight Mw 26,000 Glass transition temperature (Tg): 60 °C (A7) Styrene maleic anhydride copolymer (Product number: SMA1000, Sartomer) H / S = 50 / 50, weight average molecular weight Mw 5,500 Glass transition temperature (Tg): 155 °C

[0070] (B) Organic solvent (B1) Anone (Cyclohexanone) (Nippon Alcohol Sales Co., Ltd.) Boiling point 156 °C (B2) Diethylene glycol diethyl ether (Toho Chemical Industry Co., Ltd.) Boiling point 180 - 190 °C (B3) Acetophenone (Methyl phenyl ketone) (Tokyo Chemical Industry Co., Ltd.) Boiling point 202 °C (B4) Butyl acetate (Fuji Film Wako Pure Chemical Corporation) Boiling point 126 °C (B5) 3-Methoxy-N,N-dimethylpropanamide Boiling point 215 °C

[0071] (C) Conductive particles (C1) Flaky silver powder / Surface treatment agent: Stearic acid (Product number: AGC-GS Fukuda Metal Foil Powder Co., Ltd.) Average particle size (D50) 12.48 μm, Tap density 3.23 g / cm 3 , BET value 0.285 g / m 2 , Igros value 0.52%, Igros value / BET value 1.825 (C2) Flaky silver powder / Surface treatment agent: Stearic acid (Product number: FA618 DOWA Electronics Co., Ltd.) Average particle size (D50) 7.25 μm, Tap density 4.03 g / cm 3 , BET value 0.491 g / m 2 , Igros value 0.79%, Igros value / BET value 1.609 (C3) Flaky silver powder / Surface treatment agent: Stearic acid (Product number: AGC-B2 Fukuda Metal Foil Powder Co., Ltd.) Average particle size (D50) 6.838 μm, Tap density 4.29 g / cm 3 , BET value 0.788 g / m 2 , Igros value 0.57%, Igros value / BET value 0.723

[0072] (D) Dispersant (D1) Acidic Dispersant (manufactured by CRODA)

[0073] <Manufacture of Examples and Comparative Examples> Each material was blended so as to have the mass ratio shown in Table 1 or 2 below, and stirred and mixed using a three-roll mill to produce each conductive resin composition of Examples 1 to 15 and Comparative Examples 1 to 4.

[0074]

Table 1

[0075]

Table 2

[0076] (Physical Property Values) The measurement methods and evaluation methods for each physical property value of the examples and comparative examples are shown below.

[0077] (Solubility in Solvent) After heating each organic solvent to 60 °C, each thermoplastic resin was weighed and dissolved while stirring with a laboratory stirrer. Whether it dissolved or not was visually confirmed every hour, and if there was no residue after stirring for a total of 3 hours (if there was no residue), it was evaluated as "〇", and if there was a residue, it was evaluated as "×".

[0078] (Drying Property) A cured product obtained by drying and curing each conductive resin composition under heating conditions of 70 °C for 30 minutes was used with TGDTA, heated from 25 to 200 °C at a rate of 10 °C / min, and the mass reduction amount at 200 °C was taken as the residual solvent amount, and the drying property was confirmed by that value. A test piece with a residual solvent amount of 25 parts by mass or less with respect to the total amount of the conductive resin composition was evaluated as "〇", a test piece with a residual solvent amount of 26 parts by mass or more was evaluated as "×", and a test piece for which the evaluation itself could not be performed was evaluated as "-". Whether it could be cured at 70 °C can be represented by the die shear strength described later.

[0079] (Viscosity) Each conductive resin composition was measured for viscosity at 10 rpm using a Brookfield RVT viscometer (spindle: SC4-14 spindle, measurement temperature: 25°C). Note that Comparative Example 3 could not be measured. Those with a viscosity of 200 (Pa·s) or less were evaluated as passing.

[0080] (Die shear strength) A glass substrate was prepared for the substrate, and a 3 mm□ Si die was prepared for the die. Using a polyimide film stencil (thickness: 120 μm) with a φ2 mm hole, each conductive resin composition was printed on the glass substrate. Then, a 3 mm□ Si die was mounted and cured in an air convection oven at 70°C for 30 minutes to prepare a sample for die shear strength measurement. The die shear strength was measured at room temperature using a tabletop strength tester (model number: 4000PLUS-CART-S200KG) manufactured by Nordson DAGE. For each conductive resin composition, 10 die shear strength measurement samples were measured, and the arithmetic mean value was taken as the die shear strength. Note that Comparative Example 3 could not be measured. 0.5 (N / mm 2 ) or more were evaluated as passing.

[0081] (Dispersibility) When the particle size of the resin composition was measured by a grind gauge in accordance with the JIS standard K5400'-1990 line method, it was visually confirmed whether or not aggregates were present. When the average particle size was 10 times or more the average particle diameter (D50) of the blended (C) conductive particles, it was marked as "×"; when it was 4 times or more and less than 10 times, it was marked as "△"; when it was less than 4 times, it was marked as "〇".

[0082] (Specific resistance) On a glass substrate, two tapes with a thickness of about 85 - 95 μm were pasted in parallel at an interval of 3 mm. After printing each conductive resin composition film with a width of 3 mm × length of 50 mm × thickness of about 90 μm between these two tapes, it was cured in an air convection oven at 70 °C for 30 minutes. After measuring the film thickness of each cured conductive resin composition film, the resistance value was measured by the four-terminal method, and the specific resistance was obtained. Note that Comparative Example 3 could not be measured. In Comparative Example 4, "OverFlow" had a resistance value that was too large and exceeded the measurement range. 20×10 -4 It was evaluated as qualified when it was 20×10 Ω·cm or less.

[0083] (Elongation rate) The elongation rate was measured using a universal material testing machine Model 5566 manufactured by INSTRON (measurement conditions: tensile speed = 5 mm / min). Also, the elongation rate was defined as the amount of strain until the test piece broke in the stress-strain curve (hereinafter referred to as the SS curve) obtained from the tensile testing machine. Figure 1 shows the shape of the test piece used for measuring the elongation rate. For example, in the examples where the elongation rate was described as "70%", it means that the test piece broke when the elongation rate was 70%. Also, in the examples where ">100%" was described, it indicates that the test piece did not break even when the elongation rate exceeded 100%.

[0084] In Comparative Examples 1 and 2, the elongation rate did not meet the passing criteria. In Comparative Example 1, the ratio of the hard segment of the (A) thermoplastic resin was high. In Comparative Example 2, the weight average molecular weight of the (A) thermoplastic resin was low. In Comparative Example 3, the drying property, viscosity, die shear strength, dispersibility, specific resistance, and elongation rate could not be measured and did not meet the passing criteria. In Comparative Example 3, the boiling point of the (B) organic solvent was as low as 126 °C, and the drying property was too fast to be pasted. In Comparative Example 4, the drying property did not meet the passing criteria, and the specific resistance was OverFlow and could not be measured. In Comparative Example 4, the boiling point of the (B) organic solvent was as high as 215 °C.

[0085] From these results, it was found that a conductive resin composition containing (A) a thermoplastic resin in which the ratio of the hard segment to the soft segment (hard segment: soft segment) is 1:99 to 50:50 and the weight average molecular weight is 25,000 or more, (B) an organic solvent having a boiling point of 155°C to 205°C, and (C) conductive particles is low-temperature drying type and highly stretchable.

Claims

1. A thermoplastic resin in which the ratio of the hard segment to the soft segment (hard segment: soft segment) is from 1:99 to 50:50 and the weight average molecular weight is 25,000 or more, An organic solvent having a boiling point of 155°C to 205°C, Conductive particles, and The conductive resin composition, wherein the tap density of the (C) conductive particles is from 3.23 g / cm3 to 6.0 g / cm3.

2. A thermoplastic resin in which the ratio of the hard segment to the soft segment (hard segment: soft segment) is from 1:99 to 50:50 and the weight average molecular weight is 25,000 or more, An organic solvent having a boiling point of 155°C to 205°C, Conductive particles, and The conductive resin composition, wherein the ratio of the Igros value to the BET value (Igros value / BET value) of the (C) conductive particles is from 1.2 to 6.

0.

3. The conductive resin composition according to claim 1 or 2, wherein the (A) thermoplastic resin is at least one selected from polystyrene resins, polyolefin resins, polyvinyl chloride resins, polyurethane resins, polyester resins, polyamide resins, polybutadiene resins, hydrides thereof, and modified copolymer hydrides obtained by modifying the hydrides.

4. The conductive resin composition according to any one of claims 1 to 3, wherein the mass ratio of the (C) conductive particles to the (A) thermoplastic resin ((C):(A)) is from 95:5 to 80:

20.

5. The conductive resin composition according to any one of claims 1 to 4, wherein the average particle diameter (D50) of the (C) conductive particles is from 1 μm to 25 μm.

6. The conductive resin composition according to any one of claims 1 to 5, wherein the (C) conductive particles contain surface-treated silver particles.

7. The conductive resin composition according to any one of claims 1 to 6, further comprising (D) a dispersant.

8. The conductive resin composition according to any one of claims 1 to 7, having a viscosity of 40 Pa·s to 200 Pa·s at 25°C and 10 rpm as measured with a rotational viscometer.

9. The conductive resin composition according to any one of claims 1 to 8, wherein the elongation rate at room temperature of the cured product when the conductive resin composition is dried and cured under heating conditions of 70°C for 30 minutes is 70% or more.

10. The resistivity value of the cured product when the conductive resin composition is dried and cured under heating conditions of 70 °C for 30 minutes is 10×10 －３ The conductive resin composition according to any one of claims 1 to 8, wherein the resistivity value is 10×10 Ω·cm or less.

11. The conductive resin composition according to any one of claims 1 to 8, wherein the amount of residual solvent in the cured product when the conductive resin composition is dried and cured under heating conditions of 70°C for 30 minutes is 25 parts by mass or less based on the total amount of the conductive resin composition.

12. The conductive resin composition according to any one of claims 1 to 11, wherein the conductive resin composition is for flexible hybrid electronics.

13. A conductive adhesive comprising the conductive resin composition according to any one of claims 1 to 11.

14. A cured product obtained by curing the conductive resin composition according to any one of claims 1 to 11.

15. A semiconductor device comprising the cured product according to claim 14.

16. A laminated structure in which the cured product according to claim 14 is laminated on a substrate.

17. An electronic component using the laminated structure according to claim 16.

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