Conductive paste, rfid inlay, and method for manufacturing rfid inlay

Abstract

The present invention provides a conductive paste which can (1) improve storage stability, and can (2) improve curability, (3) improve adhesiveness, (4) make cured products have good stickiness, and (5) improve conduction reliability even when the conductive paste is mounted in a relatively short period of time. This conductive paste contains a curable compound, a curing agent, and a conductive filler, and when the conductive paste is heated from 30 DEG C to 200 DEG C at a temperature increase rate of 10 DEG C / min and differential scanning calorimetry is performed, the exothermic initiation temperature is 50-80 DEG C (inclusive).

Description

TECHNICAL FIELD

[0001] The present application relates to a conductive paste containing an electrically conductive filler. Furthermore, the present application relates to an RFID inlay using the conductive paste and a manufacturing method of the RFID inlay. BACKGROUND

[0002] As for an RFID (Radio Frequency Identification) inlay which can perform transmission and reception of data in a non-contact manner, it is widely used for a non-contact RFID tag, a non-contact RFID card, and the like. In particular, an RFID inlay of an UHF (Ultra High Frequency) band (860 MHz to 960 MHz) is attracting attention because of a long communication distance, and an RFID inlay of the UHF band is used for various products, uses such as a monthly ticket, inventory management, logistics management, and history management.

[0003] In the RFID inlay, a conductive paste containing an electrically conductive filler and an adhesive resin is applied to adhesion and connection of a chip having an electrode on a surface and a substrate having a wiring (antenna pattern) on a surface.

[0004] In recent years, along with miniaturization of electronic components using the RFID inlay, a chip used in the RFID inlay has also become miniaturized, and a conductive paste having higher adhesion and allowing higher-precision arrangement of a wiring is required.

[0005] In Patent Literature 1 below, an adhesive applicable to electronic components is disclosed. The adhesive is an acrylic adhesive composition containing a radical initiator having a 10-hour half-life temperature of 80°C or lower, an oligomer containing a vinylidene group, and at least one diluent. The adhesive can be rapidly cured at a low temperature, and a usable time of the adhesive at room temperature is 24 hours or more.

[0006] In Patent Literature 2 below, a conductive adhesive containing a polymerizable acrylic compound, an organic peroxide, and solder particles, and having a 1-minute half-life temperature of the organic peroxide lower than a solidus temperature of the solder particles is disclosed.

[0007] Prior Art Documents

[0008] Patent Literature

[0009] Patent Literature 1: Japanese Patent Application Publication No. 2006-144018

[0010] Patent Literature 2: Japanese Patent Application Publication No. 2013-124330 SUMMARY

[0011] Problems to be Solved by the Invention

[0012] The adhesives (conductive paste) described in Patent Literatures 1 and 2 can improve adhesion to some extent. However, in the conventional conductive paste, when an electronic component is prepared (mounted) using the conductive paste in an air atmosphere, the polymerization reaction of the conductive paste cannot sufficiently proceed due to the influence of oxygen, and sometimes, an uncured portion is present in the cured product of the conductive paste. As a result, there are technical problems that the adhesion cannot be sufficiently improved, the tackiness of the cured product cannot be good, and the conduction reliability of the obtained electronic component cannot be sufficiently improved. The technical problems are more remarkable in the case of mounting in a relatively short time (for example, within 15 seconds).

[0013] In addition, generally, when the curing property of an adhesive (conductive paste) is improved, there is a tendency that the pot life (usable time) becomes short. In the conventional adhesive (conductive paste), it is difficult to improve the curing property of the adhesive (conductive paste) and to improve the storage stability.

[0014] An object of the present application is to provide a conductive paste which 1) improves the storage stability, and 2) can improve the curing property even in the case of mounting in a short time, 3) can improve the adhesion, 4) can make the tackiness of the cured product good, and 5) can improve the conduction reliability. In addition, an object of the present application is also to provide an RFID inlay using the conductive paste and a manufacturing method of an RFID inlay.

[0015] Technical means for solving the problem

[0016] A conductive paste, an RFID inlay, and a manufacturing method of an RFID inlay disclosed in the present specification are as follows.

[0017] Item 1. A conductive paste which is a conductive paste containing a curable compound, a curing agent, and a conductive filler, wherein

[0018] When differential scanning calorimetry is performed on the conductive paste by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the exothermic onset temperature is 50°C or higher and 80°C or lower.

[0019] Item 2. A conductive paste which is a conductive paste containing a curable compound, a curing agent, and a conductive filler, wherein

[0020] The curing agent contains a secondary thiol curing agent or a primary thiol curing agent having no ester skeleton,

[0021] The conductive filler is a conductive particle having a resin particle and a conductive layer disposed on the surface of the resin particle, or a metal particle having a melting point of more than 450°C.

[0022] Item 3. The conductive paste according to item 1 or 2, wherein

[0023] The curable compound includes a glycidyl amine type epoxy compound.

[0024] Item 4. The conductive paste according to any one of items 1 to 3, wherein

[0025] The curing agent includes a thiol curing agent having two or more thiol groups.

[0026] Item 5. The conductive paste according to any one of items 1 to 4, wherein

[0027] The curing agent includes a thiol curing agent having a structure represented by the following formula (1),

[0028] [Chemical Formula 1]

[0029]

[0030] In the formula (1), R1, R2, R3, and R4 each represent an alkylene group having a carbon atom number of 1 to 5.

[0031] Item 6. The conductive paste according to any one of items 1 to 5, wherein

[0032] The curing agent includes a secondary thiol curing agent or a primary thiol curing agent having no ester skeleton,

[0033] The content of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton is 5% by weight or more and 50% by weight or less in 100% by weight of the conductive paste.

[0034] Item 7. The conductive paste according to any one of items 1 to 6, wherein

[0035] The curing agent includes a secondary thiol curing agent.

[0036] Item 8. The conductive paste according to any one of items 1 to 7, wherein

[0037] When differential scanning calorimetry is performed on the conductive paste by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the exothermic end temperature is 85°C or higher and 180°C or lower.

[0038] Item 9. The conductive paste according to any one of items 1 to 8, wherein

[0039] When differential scanning calorimetry is performed on the conductive paste by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the absolute value of the difference between the exothermic start temperature and the exothermic end temperature is 5°C or higher and 100°C or lower.

[0040] Item 10. The conductive paste according to any one of items 1 to 9, wherein

[0041] The curing agent includes a microcapsule type curing agent.

[0042] Item 11. The conductive paste according to item 10, wherein,

[0043] The content of the microcapsule type curing agent is 5% by weight or more and 40% by weight or less in 100% by weight of the conductive paste 100.

[0044] Item 12. The conductive paste according to any one of items 1 to 11, wherein,

[0045] The particle diameter of the electrically conductive filler is 10 μm or less.

[0046] Item 13. The conductive paste according to any one of items 1 to 12, wherein,

[0047] The content of the electrically conductive filler is 0.1% by weight or more and 50% by weight or less in 100% by weight of the conductive paste 100.

[0048] Item 14. The conductive paste according to any one of items 1 to 13, wherein,

[0049] The curing agent includes an amine curing agent that is solid at 25°C.

[0050] Item 15. The conductive paste according to any one of items 1 to 14, further comprising a chelating agent.

[0051] Item 16. The conductive paste according to item 15, wherein,

[0052] The chelating agent includes a borate ester.

[0053] Item 17. The conductive paste according to any one of items 1 to 16, further comprising a non-electrically conductive filler.

[0054] Item 18. The conductive paste according to item 17, wherein,

[0055] The ratio of the particle diameter of the non-electrically conductive filler to the particle diameter of the electrically conductive filler is 0.5 or less.

[0056] Item 19. The conductive paste according to any one of items 1 to 18, used for obtaining an RFID inlay.

[0057] Item 20. An RFID inlay, comprising:

[0058] a substrate having a wiring on a surface,

[0059] a chip having an electrode on a surface, and

[0060] an adhesive portion that realizes adhesion of the substrate and the chip,

[0061] The material of the adhesive portion is the conductive paste described in any one of items 1 to 19,

[0062] The wiring and the electrode are electrically connected by the conductive filler in the adhesive portion.

[0063] Item 21. A manufacturing method of an RFID inlay, comprising:

[0064] A first placement step of placing the conductive paste described in any one of items 1 to 19 on a surface of a substrate having a wiring on the surface;

[0065] A second placement step of placing a chip having an electrode on a surface of the conductive paste on a surface opposite to the substrate side; and

[0066] An adhesive step of forming an adhesive portion that adhesively connects the substrate and the chip from the conductive paste by heating and pressing the conductive paste, and electrically connecting the wiring and the electrode by the conductive filler in the adhesive portion.

[0067] Item 22. The manufacturing method of an RFID inlay according to item 21, wherein

[0068] The substrate is long and thin,

[0069] In the first placement step, the second placement step, and the adhesive step, the long and thin substrate is transported by a roll-to-roll method to manufacture the RFID inlay.

[0070] Effects of the Invention

[0071] The conductive paste of the present application is a conductive paste containing a curable compound, a curing agent, and a conductive filler, wherein, when differential scanning calorimetry is performed on the conductive paste by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the exothermic onset temperature is 50°C or higher and 80°C or lower. In the conductive paste of the present application, because of the above-described configuration, 1) the storage stability is improved, and even in the case of installation in a short period of time, 2) the curability can be improved, 3) the adhesion can be improved, 4) the tackiness of the cured product can be good, and 5) the conduction reliability can be improved.

[0072] Further, another conductive paste of the present application is a conductive paste containing a curable compound, a curing agent, and a conductive filler, wherein the curing agent contains a secondary mercaptan curing agent or a primary mercaptan curing agent having no ester skeleton, and the conductive filler is a conductive particle having a resin particle and a conductive layer disposed on the surface of the resin particle, or a metal particle having a melting point exceeding 450°C. In the conductive paste of the present application, because of the constitution, 1) the storage stability is improved, and even in the case of installation in a short time, 2) the curability is improved, 3) the adhesion is improved, 4) the tackiness of the cured product is good, and 5) the conduction reliability is improved. BRIEF DESCRIPTION OF DRAWINGS

[0073] [ Figure 1 ] Figure 1 is a cross-sectional view schematically showing an RFID inlay using the conductive paste of the first embodiment of the present application. DETAILED DESCRIPTION

[0074] Hereinafter, the present application is described in detail.

[0075] (Conductive paste)

[0076] The conductive paste of the present application (first conductive paste) is a conductive paste containing a curable compound, a curing agent, and a conductive filler. In the conductive paste of the present application (first conductive paste), when the conductive paste is subjected to differential scanning calorimetry measurement by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the exothermic onset temperature is 50°C or higher and 80°C or lower.

[0077] Further, the conductive paste of the present application (second conductive paste) is a conductive paste containing a curable compound, a curing agent, and a conductive filler. In the conductive paste of the present application (second conductive paste), the curing agent contains a secondary mercaptan curing agent or a primary mercaptan curing agent having no ester skeleton. In the conductive paste of the present application (second conductive paste), the conductive filler is a conductive particle having a resin particle and a conductive layer disposed on the surface of the resin particle, or a metal particle having a melting point exceeding 450°C.

[0078] In the past, in the case where an electronic component is prepared (mounted) using a conductive paste in an air atmosphere, the polymerization of the conductive paste cannot be sufficiently performed due to the influence of oxygen, and sometimes, an uncured portion is present in the cured product of the conductive paste. As a result, there is a technical problem in that the adhesiveness cannot be sufficiently improved, and the conduction reliability of the obtained electronic component cannot be sufficiently improved. This problem is more remarkable in the case where only a (meth)acrylate compound as a curing compound is subjected to radical polymerization, in the case where mounting is performed at a low temperature (for example, 160°C to 200°C), or in the case where mounting is performed for a short time (for example, 15 seconds or less). In addition, in the past adhesive (conductive paste), it is difficult to improve the curability of the adhesive (conductive paste) and to improve the storage stability.

[0079] The present inventors have found that the technical problem can be solved by controlling the exothermic onset temperature at the time of differential scanning calorimetry of the conductive paste in a specific range. In addition, the present inventors have found that the technical problem can be solved by using a conductive paste having a specific composition.

[0080] That is, in the conductive paste of the present application, since the above-described configuration is provided, the pot life (usable time) can be extended (the storage stability can be improved). In addition, in the conductive paste of the present application, since the above-described configuration is provided, even in the case where mounting (heating) is performed for a short time (for example, 15 seconds or less), the curability can be improved, and sufficient curing can be performed. In particular, in the second conductive paste, since the above-described configuration is provided, even in the case where mounting (heating) is performed at a low temperature (for example, 160°C to 200°C) and for a short time (for example, 15 seconds or less), the curability can be improved, and sufficient curing can be performed. In addition, in the conductive paste of the present application, since the above-described configuration is provided, even in the case where mounting is performed for a short time, the adhesiveness can be improved, the tackiness of the cured product can be made good, and the conduction reliability can be improved.

[0081] The conductive paste is subjected to differential scanning calorimetry (DSC) by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute. In the differential scanning calorimetry, in the conductive paste of the present application (first conductive paste), the exothermic onset temperature is 50°C or higher and 80°C or lower. In the differential scanning calorimetry, in the second conductive paste, the exothermic onset temperature is preferably 50°C or higher and 80°C or lower. Note that, in the present specification, the exothermic onset temperature refers to the temperature of the portion where the exothermic amount starts to increase from the baseline. In addition, in the present specification, the exothermic end temperature refers to the temperature of the portion where, after reaching the peak of the exothermic amount, the exothermic amount decreases to 1% of the exothermic amount at the peak of the exothermic amount.

[0082] The differential scanning calorimetry (DSC) can be performed by the following method. A differential scanning calorimetry device is prepared. 5 mg of the conductive paste is taken into a special aluminum pan, and a special jig is used to close the lid. The special aluminum pan and an empty aluminum pan (control) are set in the heating device, and observation of the reversible heat flow and irreversible heat flow is performed at a temperature increase rate of 10°C / min from 30°C to 200°C in an air atmosphere. The exothermic peak observed in the irreversible heat flow is taken as the exothermic peak of the conductive paste. As the differential scanning calorimetry device, "TA7000" manufactured by HITACHI HIGH-TECH SCIENCE Co., Ltd., or the like can be given.

[0083] In the differential scanning calorimetry, the exothermic onset temperature can be measured. From the viewpoint of improving the storage stability and ejection stability of the conductive paste, further improving the conduction reliability in the case of installation in a short period of time, the exothermic onset temperature is preferably 50°C or higher, more preferably 55°C or higher, further preferably 60°C or higher, and preferably 80°C or lower, more preferably 75°C or lower, further preferably 70°C or lower.

[0084] In the differential scanning calorimetry, the exothermic peak top temperature can be measured. From the viewpoint of further improving the conduction reliability in the case of installation in a short period of time, the exothermic peak top temperature is preferably 80°C or higher, more preferably 90°C or higher, further preferably 100°C or higher, and preferably 145°C or lower, more preferably 140°C or lower, further preferably 130°C or lower.

[0085] In the differential scanning calorimetry, the exothermic end temperature can be measured. From the viewpoint of further improving the conduction reliability in the case of installation in a short period of time, the exothermic end temperature is preferably 85°C or higher, more preferably 90°C or higher, further preferably 95°C or higher, particularly preferably 100°C or higher, and preferably 180°C or lower, more preferably 175°C or lower, further preferably 170°C or lower.

[0086] In the differential scanning calorimetry, as a method of adjusting the exothermic onset temperature, the exothermic peak top temperature, and the exothermic end temperature to the above-mentioned preferable ranges, a method of increasing the content of the curing agent with respect to the content of the curable compound, and a method of adjusting the kind and combination of the curing agent, and the like can be given.

[0087] In the differential scanning calorimetry, the absolute value of the difference between the exothermic starting temperature and the exothermic ending temperature is preferably 5°C or more, more preferably 10°C or more, further preferably 15°C or more, particularly preferably 20°C or more, preferably 100°C or less, more preferably 95°C or less, further preferably 90°C or less, particularly preferably 85°C or less, most preferably 80°C or less. When the absolute value of the difference between the exothermic starting temperature and the exothermic ending temperature is the lower limit or more and the upper limit or less, the storage stability of the conductive paste can be improved, and the conduction reliability can be further improved even when the installation is performed in a short time.

[0088] In the differential scanning calorimetry, the number of exothermic peaks is preferably one. In the differential scanning calorimetry, the number of exothermic peaks is preferably only one. In the differential scanning calorimetry, the number of exothermic peaks is preferably not more than two.

[0089] The conductive paste of the present application is in a paste form at 25°C. The conductive paste is used by being jetted at, for example, 20°C to 50°C. The conductive paste of the present application is preferably used by being jetted by a jet dispenser.

[0090] The viscosity (η25) of the conductive paste at 25°C is preferably 15 Pa-s or more, more preferably 25 Pa-s or more, further preferably 40 Pa-s or more, preferably 200 Pa-s or less, more preferably 150 Pa-s or less, further preferably 100 Pa-s or less. When the viscosity (η25) is the lower limit or more, the conductive paste can be inhibited from flowing out from the wiring. When the viscosity (η25) is the upper limit or less, the conductive paste can be disposed on the fine wiring with high precision.

[0091] The viscosity (η25) can be measured using, for example, an E-type viscometer under the conditions of 25°C and 5 rpm for the just-prepared conductive paste. As the E-type viscometer, "TV35-type viscometer" manufactured by Tokimec, Inc. or the like can be mentioned.

[0092] The ratio of the viscosity (ηα) of the conductive paste after the conductive paste is stored at 25°C and 50% RH for 24 hours to the viscosity (η25) of the conductive paste immediately after preparation at 25°C is set as the ratio (viscosity after storage (ηα) / viscosity immediately after preparation (η25)). The ratio (viscosity after storage (ηα) / viscosity immediately after preparation (η25)) is preferably 0.7 or greater, more preferably 0.8 or greater, further preferably 0.9 or greater, and preferably 1.25 or less, more preferably less than 1.25, further preferably 1.2 or less, and particularly preferably 1.1 or less. When the ratio (viscosity after storage (ηα) / viscosity immediately after preparation (η25)) is the lower limit or greater, the storage stability can be further improved, and the conductive paste can be inhibited from flowing out from the wiring. When the ratio (viscosity after storage (ηα) / viscosity immediately after preparation (η25)) is the upper limit or less, the conductive paste can be accurately disposed on the fine wiring.

[0093] The viscosity (ηα) after storage can be measured, for example, by using an E-type viscometer under the conditions of 25°C and 5 rpm after the conductive paste is stored in a constant temperature and humidity chamber at 25°C and 50% RH for 24 hours. As the E-type viscometer, for example, "TV35-type viscometer" manufactured by Tokimec, Inc. can be used.

[0094] The conductive paste has good adhesiveness. The conductive paste is suitable for use as an adhesive. The conductive paste is particularly suitable for use in adhesion of a substrate and a chip.

[0095] From the viewpoint of further improving the conduction reliability, the conductive paste is preferably an anisotropic conductive paste. The conductive paste is suitable for use in electrical connection of an electrode. The conductive paste is suitable for use in obtaining a connection structure. The conductive paste is suitable for use in obtaining an electronic component. The conductive paste is particularly suitable for use in obtaining an RFID inlay (use of the conductive paste for obtaining an RFID inlay). The conductive paste is suitable for use in adhesion and connection of a chip having an electrode on a surface and a substrate having a wiring (antenna pattern) on a surface (use of the conductive paste for adhesion and connection of a chip having an electrode on a surface and a substrate having a wiring (antenna pattern) on a surface).

[0096] Hereinafter, each component included in the conductive paste will be described.

[0097] Note that, in the present specification, "(meth)acrylate" means acrylate and methacrylate. "(Meth)acrylic" means acrylic and methacrylic.

[0098] <Curable Compound>

[0099] As the curable compound, a thermally curable compound and a photo-curable compound, etc. can be given. The curable compound is preferably a thermally curable compound. The thermally curable compound is a compound capable of being cured by heating. As the thermally curable compound, a (meth)acrylic compound, an oxetane compound, an epoxy compound, a ring sulfur compound, a phenol compound, an amino compound, an unsaturated polyester compound, a polyurethane compound, a polysiloxane compound, and a polyimide compound, etc. can be given. The curable compound can be used singly or in combination of two or more.

[0100] From the viewpoint of further improving the conduction reliability also in the case of installation in a short time, the curable compound preferably contains an epoxy compound.

[0101] As the epoxy compound, a glycidyl amine type epoxy compound, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a bisphenol S type epoxy compound, a phenol novolac type epoxy compound, a biphenyl type epoxy compound, a biphenyl novolac type epoxy compound, a biphenyl phenol type epoxy compound, a naphthalene type epoxy compound, a fluorene type epoxy compound, a phenol aralkyl type epoxy compound, a naphthol aralkyl type epoxy compound, a dicyclopentadiene type epoxy compound, an anthracene type epoxy compound, an epoxy compound having a diamond skeleton, an epoxy compound having a tricyclodecane skeleton, a naphthalene ether type epoxy compound, and an epoxy compound having a triazine nucleus in the skeleton, etc. can be given.

[0102] From the viewpoint of further improving the conduction reliability also in the case of installation in a short time, the curable compound is more preferably contains a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, or a glycidyl amine type epoxy compound, and further preferably contains a glycidyl amine type epoxy compound. In particular, in the first conductive paste, from the viewpoint of further improving the conduction reliability also in the case of installation in a short time, the curable compound is further preferably contains a glycidyl amine type epoxy compound.

[0103] In particular, in the second conductive paste, from the viewpoint of further improving the curability also in the case of installation (heating) at a low temperature and in a short time, and further improving the storage stability, the curable compound is further preferably contains a bisphenol A type epoxy compound or a bisphenol F type epoxy compound. In this case, the curable compound can contain at least one of a bisphenol A type epoxy compound and a bisphenol F type epoxy compound, or both.

[0104] The molecular weight of the curable compound is preferably 350 or more, more preferably 400 or more, further preferably 450 or more, particularly preferably 500 or more, preferably 4500 or less, more preferably 4000 or less, further preferably 3500 or less, particularly preferably 3000 or less. When the molecular weight of the curable compound is within the range, the viscosity of the conductive paste can be adjusted to an appropriate range, and the on-off reliability can be further improved.

[0105] In the case where the structural formula of the curable compound can be determined, the molecular weight of the curable compound refers to the molecular weight that can be calculated from the structural formula. In addition, in the case where the structural formula of the curable compound cannot be determined, the molecular weight means the weight average molecular weight. The weight average molecular weight indicates the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC). The curable compound is generally able to determine the structural formula because the molecular weight is relatively small. The weight average molecular weight can be measured by the following measuring device and measuring conditions.

[0106] Measuring device: Waters GPC System (Waters 2690 + Waters 2414 (RI)) manufactured by WATERS Corporation

[0107] Column: Shodex GPC LF-G x 1, Shodex GPC LF-804 x 2

[0108] Mobile phase: THF 1.0 mL / min

[0109] Sample concentration: 5 mg / mL

[0110] Detector: differential refractive index detector (RID)

[0111] Standard substance: polystyrene (manufactured by TOSOH Corporation, weight average molecular weight: 620 to 590,000)

[0112] The content of the curable compound in the conductive paste 100 is preferably 15% by weight or more, more preferably 20% by weight or more, preferably 90% by weight or less, more preferably 80% by weight or less, further preferably 70% by weight or less. When the content of the curable compound is the lower limit or more and the upper limit or less, the curability can be further improved, the adhesion can be further improved, the tackiness of the cured product can be further good, and the on-off reliability can be further improved even in the case of mounting in a short time. Note that, in the case where the curable compound contains two or more curable compounds, the content of the curable compound refers to the total content of the two or more curable compounds.

[0113] The content of the epoxy compound in the conductive paste 100 is preferably 15% by weight or more, more preferably 20% by weight or more, and is preferably 90% by weight or less, more preferably 80% by weight or less, and further preferably 70% by weight or less. When the content of the epoxy compound is the lower limit or more and the upper limit or less, the curability can be further improved even in the case of installation in a short period of time, the adhesion can be further improved, the tackiness of the cured product can be further improved, and the on-off reliability can be further improved.

[0114] The content of the glycidyl amine type epoxy compound in the conductive paste 100 is preferably 15% by weight or more, more preferably 20% by weight or more, and is preferably 90% by weight or less, more preferably 80% by weight or less, and further preferably 70% by weight or less. When the content of the glycidyl amine type epoxy compound is the lower limit or more and the upper limit or less, the curability can be further improved even in the case of installation in a short period of time, the adhesion can be further improved, the tackiness of the cured product can be further improved, and the on-off reliability can be further improved.

[0115] The content of the total of the bisphenol A type epoxy compound and the bisphenol F type epoxy compound in the conductive paste 100 is preferably 15% by weight or more, more preferably 20% by weight or more, and is preferably 90% by weight or less, more preferably 80% by weight or less, and further preferably 70% by weight or less. When the content of the total of the bisphenol A type epoxy compound and the bisphenol F type epoxy compound is the lower limit or more and the upper limit or less, the curability can be further improved even in the case of installation (heating) in a low temperature and a short period of time. In addition, the adhesion can be further improved even in the case of installation in a short period of time, the tackiness of the cured product can be further improved, and the on-off reliability can be further improved. When the curability compound contains only one of the bisphenol A type epoxy compound and the bisphenol F type epoxy compound, the content of the total of the bisphenol A type epoxy compound and the bisphenol F type epoxy compound refers to the content of the one compound. When the curability compound contains both the bisphenol A type epoxy compound and the bisphenol F type epoxy compound, the content of the total of the bisphenol A type epoxy compound and the bisphenol F type epoxy compound refers to the total content of both compounds.

[0116] <Curative>

[0117] The curative is not particularly limited. As the curative, a curative that can cure the curability compound can be appropriately used. The curative can contain a curing accelerator.

[0118] As the curing agent, a phenol compound (phenol curing agent), an active ester compound, a carbodiimide compound (carbodiimide curing agent), an amine compound (amine curing agent), a thiol compound (thiol curing agent), a phosphine compound, dicyandiamide, and an anhydride, and the like can be given. The curing agent preferably has a functional group capable of reacting with the epoxy group of the epoxy compound. The curing agent can be used singly or in combination of two or more.

[0119] From the viewpoint of further improving the curability even in the case of installation in a short time, the curing agent preferably contains a thiol compound (thiol curing agent) or an amine compound (amine curing agent), more preferably contains a thiol compound (thiol curing agent), further preferably contains a thiol compound (thiol curing agent) and an amine compound (amine curing agent).

[0120] The thiol compound (thiol curing agent) can be a primary thiol compound (primary thiol curing agent), can be a secondary thiol compound (secondary thiol curing agent).

[0121] In the second conductive paste, the curing agent contains a secondary thiol curing agent, or a primary thiol curing agent having no ester skeleton. In this case, the curing agent can contain only at least one of a secondary thiol curing agent and a primary thiol curing agent having no ester skeleton, or can contain both.

[0122] The "secondary thiol" means a compound having a structure in which the carbon atom to which the SH group is bonded has one side chain. The "primary thiol" means a compound in which the carbon atom to which the SH group is bonded has no side chain.

[0123] In the first conductive paste, the curing agent preferably contains a secondary thiol curing agent, or a primary thiol curing agent having no ester skeleton.

[0124] In the first conductive paste and the second conductive paste, the curing agent can contain a primary thiol curing agent having no ester skeleton, and can contain a secondary thiol curing agent. The secondary thiol curing agent can have an ester skeleton, or can have no ester skeleton. That is, in the second conductive paste, the curing agent can contain a primary thiol curing agent having no ester skeleton, can contain a secondary thiol curing agent having an ester skeleton, and can contain a secondary thiol curing agent having no ester skeleton.

[0125] As the primary thiol compound (primary thiol curing agent), 3-mercapto propyl stearate, 2-ethyl-2-{[(3-mercapto propionyl)oxy]methyl}propane-1,3-diyl bis(3-mercapto propionate), methoxybutyl-β-mercapto propionate, and 2-{2,4,6-trioxo-3,5-bis[2-(3-mercapto propionyloxy)ethyl]-1,3,5-triazin-1-yl}ethyl 3-sulfanyl propionate, and the like can be given.

[0126] As the primary thiol compound (primary thiol curing agent) not having an ester skeleton, tetrahydro-l,3,4,6-tetrakis(3-mercaptopropyl)-imidazo[4,5-d]imidazole-2,5(lH,3H)-dione, tetrahydro-l,3,4,6-tetrakis(3-mercaptoethyl)-imidazo[4,5-d]imidazole-2,5(lH,3H)-dione, 3-(3-mercapto-propoxy)-2,2-bis-(3-mercapto-propoxymethyl)-propane-l-ol, and 3-{3-(3-mercapto-propoxy)-2,2-bis-[(3-mercapto-propoxy)methyl]propoxy}-propane-l-ol, and the like can be given.

[0127] As the secondary thiol compound (secondary thiol curing agent), pentaerythritol tetra(3-mercapto butyrate), 1,4-bis(3-mercapto butyryloxy)butane, 1,3,5-tris(2-(3-mercapto butyryloxy)ethyl)-l,3,5-triazine-2,4,6-trione, and trimethylolpropane tri(3-mercapto butyrate), and the like can be given.

[0128] From the viewpoint of further improving the curability also in the case of installation in a shorter time, the thiol compound (thiol curing agent) is preferably a secondary thiol compound (secondary thiol curing agent). From the viewpoint of further improving the curability also in the case of installation in a shorter time, the curing agent preferably contains a secondary thiol compound (secondary thiol curing agent).

[0129] From the viewpoint of further improving the curability also in the case of installation (heating) at a lower temperature and in a shorter time, the conductive paste preferably contains a thiol curing agent not having an ester skeleton. From the viewpoint of further improving the curability also in the case of installation (heating) at a lower temperature and in a shorter time, the conductive paste preferably contains a primary thiol curing agent not having an ester skeleton, or a secondary thiol curing agent not having an ester skeleton.

[0130] From the viewpoint of further improving the curability also in the case of installation (heating) at a lower temperature and in a shorter time, the conductive paste preferably contains a thiol curing agent having 2 or more thiol groups. From the viewpoint of further improving the curability also in the case of installation (heating) at a lower temperature and in a shorter time, the number of thiol groups in the thiol curing agent is preferably 2 or more, more preferably 3 or more, and further preferably 4 or more. The number of thiol groups in the thiol curing agent can be 10 or less, or 6 or less. The range of the number of thiol groups in the thiol curing agent can be set by appropriately selecting the lower limit value and the upper limit value.

[0131] From the viewpoint of further improving the curability also in the case of installation (heating) at a lower temperature and in a shorter time, the conductive paste particularly preferably contains a thiol curing agent having 2 or more thiol groups and not having an ester skeleton.

[0132] From the viewpoint of further improving the curability even in the case of mounting (heating) at a lower temperature and for a shorter time, the conductive paste particularly preferably contains a mercaptan curing agent having a structure represented by the following formula (1).

[0133] [Chemical Formula 2]

[0134]

[0135] In the formula (1), R1, R2, R3, and R4 each represent an alkylene group having 1 to 5 carbon atoms.

[0136] In the formula (1), the alkylene group of R1, R2, R3, and R4 can have 2 or more carbon atoms.

[0137] The mercaptan curing agent having a structure represented by the formula (1) is a mercaptan curing agent having 2 or more mercaptan groups and not having an ester skeleton.

[0138] In the formula (1), R1, R2, R3, and R4 can be the same or different.

[0139] From the viewpoint of further improving the curability even in the case of mounting (heating) at a lower temperature and for a shorter time, in the formula (1), R1, R2, R3, and R4 are each preferably an alkylene group having 2 or 3 carbon atoms. From the viewpoint of further improving the curability even in the case of mounting (heating) at a lower temperature and for a shorter time, in the formula (1), the alkylene group of R1, R2, R3, and R4 preferably has 2 or 3 carbon atoms.

[0140] The curing agent preferably contains tetrahydro-1,3,4,6-tetrakis(3-mercaptopropyl)- imidazol[4,5-d]imidazole-2,5(lH,3H)-dione or tetrahydro-1,3,4,6-tetrakis(3- mercaptoethyl)-imidazol[4,5-d]imidazole-2,5(lH,3H)-dione. In this case, the curability can be further improved even in the case of mounting (heating) at a lower temperature and for a shorter time. The curing agent more preferably contains tetrahydro-1,3,4,6-tetrakis(3- mercaptopropyl)-imidazol[4,5-d]imidazole-2,5(lH,3H)-dione. In this case, the curability can be further improved even in the case of mounting (heating) at a lower temperature and for a shorter time.

[0141] As the amine compound (amine curing agent), dihydrazide compounds, diethylamine, triethylamine, diethylenetriamine, triethylenetetramine, and 4,4-dimethylaminopyridine, and the like can be given. The amine compound (amine curing agent) can be an amine adduct type curing agent.

[0142] The amine compound (amine curing agent) is preferably solid at 25°C. The curing agent preferably contains an amine compound (amine curing agent) that is solid at 25°C.

[0143] The melting point of the amine compound (amine curing agent) that is solid at 25°C is preferably 50°C or higher, more preferably 55°C or higher, further preferably 60°C or higher, and preferably 180°C or lower, more preferably 175°C or lower, further preferably 170°C or lower. When the melting point is the lower limit or higher and the upper limit or lower, the curability can be further improved even in the case of installation in a short period of time, and the adhesion of the cured product is further improved.

[0144] The melting point of the amine compound (amine curing agent) that is solid at 25°C can be calculated from the endothermic peak, for example, by differential scanning calorimetry (DSC).

[0145] The curing agent preferably contains a secondary thiol compound (secondary thiol curing agent) and an amine compound (amine curing agent) that is solid at 25°C.

[0146] From the viewpoint of further improving the storage stability, the curing agent preferably contains a microcapsule-type curing agent.

[0147] The microcapsule-type curing agent can use a commercially available product. As the commercially available product of the microcapsule-type curing agent, NOVACURE HX3088, NOVACURE HX3941, NOVACURE HXA4922HP, NOVACURE HX3742, NOVACURE HX3722, and NOVACURE HXA9042HP (all of which are manufactured by Asahi Kasei E-Materials Co., Ltd.) and the like can be given.

[0148] From the viewpoint of further improving the storage stability, the curing agent particularly preferably contains a secondary thiol curing agent or a primary thiol curing agent having no ester skeleton and the microcapsule-type curing agent.

[0149] The content of the curing agent in the conductive paste 100 of 100% by weight is preferably 5% by weight or more, more preferably 10% by weight or more, further preferably 15% by weight or more, and preferably 50% by weight or less, more preferably 45% by weight or less, further preferably 40% by weight or less. When the content of the curing agent is the lower limit or more and the upper limit or less, the curability can be further improved even in the case of installation in a short period of time, the adhesion can be further improved, the adhesion of the cured product can be further improved, and the on-off reliability can be further improved. Note that, in the case where the curing agent contains two or more kinds of curing agents, the content of the curing agent indicates the total content of the two or more kinds of curing agents. (The same applies hereinafter)

[0150] The content of the curing agent is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, and preferably 90 parts by weight or less, more preferably 80 parts by weight or less, relative to 100 parts by weight of the content of the curable compound. When the content of the curing agent is the lower limit or more and the upper limit or less, the curability can be further improved, the adhesion can be further improved, the tackiness of the cured product can be further improved, and the conduction reliability can be further improved even in the case of installation in a short time.

[0151] The content of the secondary mercaptan curing agent is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more, and is preferably 50% by weight or less, more preferably 45% by weight or less, and further preferably 40% by weight or less, in 100% by weight of the conductive paste. When the content of the secondary mercaptan curing agent is the lower limit or more and the upper limit or less, the curability can be further improved, the adhesion can be further improved, the tackiness of the cured product can be further improved, and the conduction reliability can be further improved even in the case of installation in a short time.

[0152] The total content of the secondary mercaptan curing agent and the amine curing agent that is solid at 25°C is preferably 7% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more, and is preferably 50% by weight or less, more preferably 45% by weight or less, and further preferably 40% by weight or less, in 100% by weight of the conductive paste. When the total content of the secondary mercaptan curing agent and the amine curing agent that is solid at 25°C is the lower limit or more and the upper limit or less, the curability can be further improved, the adhesion can be further improved, the tackiness of the cured product can be further improved, and the conduction reliability can be further improved even in the case of installation in a short time.

[0153] The total content of the secondary mercaptan curing agent and the amine curing agent that is solid at 25°C is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, and preferably 90 parts by weight or less, more preferably 80 parts by weight or less, relative to 100 parts by weight of the content of the curable compound. When the total content of the secondary mercaptan curing agent and the amine curing agent that is solid at 25°C is the lower limit or more and the upper limit or less, the curability can be further improved, the adhesion can be further improved, the tackiness of the cured product can be further improved, and the conduction reliability can be further improved even in the case of installation in a short time.

[0154] The content of the total of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more, and is preferably 50% by weight or less, more preferably 45% by weight or less, and further preferably 40% by weight or less, in 100% by weight of the conductive paste 100. When the content of the total of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton is the lower limit or more and the upper limit or less, the curability can be further improved even when installation (heating) is performed at a lower temperature and for a shorter period of time. In addition, when the content of the total of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton is the lower limit or more and the upper limit or less, the adhesion can be further improved, the tackiness of the cured product can be further improved, and the on-off reliability can be further improved. Note that, when the curing agent contains only one of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton, the content of the total of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton indicates the content of the one curing agent. When the curing agent contains both the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton, the content of the total of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton indicates the content of the total of both the curing agents.

[0155] The content of the microcapsule-type curing agent is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more, and is preferably 50% by weight or less, more preferably 45% by weight or less, and further preferably 40% by weight or less, in 100% by weight of the conductive paste 100. When the content of the microcapsule-type curing agent is the lower limit or more and the upper limit or less, the storage stability can be further improved.

[0156] <Conductive filler>

[0157] The conductive filler is not particularly limited. The conductive filler can be a conductive particle, and can be a carbon fiber.

[0158] From the viewpoint of further improving the conduction reliability, in the first conductive paste, the electrically conductive filler is preferably an electrically conductive particle having a resin particle and an electrically conductive layer disposed on the surface of the resin particle, or a metal particle having a melting point exceeding 450°C. In the second conductive paste, the electrically conductive filler is an electrically conductive particle having a resin particle and an electrically conductive layer disposed on the surface of the resin particle, or a metal particle having a melting point exceeding 450°C. In the second conductive paste, the electrically conductive filler can be an electrically conductive particle having a resin particle and an electrically conductive layer disposed on the surface of the resin particle, or a metal particle having a melting point exceeding 450°C. In the electrically conductive particle having a resin particle and an electrically conductive layer disposed on the surface of the resin particle, the resin particle is a base material particle. From the viewpoint of further improving the conduction reliability, in the first conductive paste, the electrically conductive filler is preferably a metal particle having a melting point exceeding 450°C. From the viewpoint of further improving the conduction reliability, in the second conductive paste, the electrically conductive filler is preferably a metal particle having a melting point exceeding 450°C.

[0159] The electrically conductive filler in the second conductive paste is different from the solder particle. In the second conductive paste, because of the constitution, it is possible to improve the jetting stability of the conductive paste. As the electrically conductive filler, in the case of using only a metal particle (for example, a solder particle) having a melting point of 450°C or less, it is difficult to sufficiently improve the jetting stability of the conductive paste compared to the case of using a metal particle having a melting point exceeding 450°C.

[0160] In the conductive paste (particularly, the first conductive paste), the shape of the electrically conductive filler is not particularly limited. The shape of the electrically conductive filler can be spherical, can be a shape other than spherical, or can be flat, and the like.

[0161] In the conductive paste (particularly, the first conductive paste), the electrically conductive filler is preferably an electrically conductive particle. The electrically conductive particle can be a solder particle, or a metal particle. The metal particle can be a metal powder. The electrically conductive particle can have a base material particle, and an electrically conductive portion disposed on the surface of the base material particle. From the viewpoint of further improving the conduction reliability, the electrically conductive particle preferably has a base material particle, and an electrically conductive portion disposed on the surface of the base material particle.

[0162] In the conductive paste (particularly, the first conductive paste), in the case where the electrically conductive filler is an electrically conductive particle, the particle diameter of the electrically conductive particle is preferably 0.1 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, and is preferably 100 μm or less, more preferably 30 μm or less, and further preferably 10 μm or less. When the particle diameter of the electrically conductive particle is the lower limit or more and the upper limit or less, it is possible to further improve the conduction reliability even in the case of mounting in a short time.

[0163] The particle diameter of the conductive filler in the conductive paste is preferably 0.1 μm or more, more preferably 1 μm or more, and further preferably 2 μm or more, and is preferably 100 μm or less, more preferably 30 μm or less, and further preferably 10 μm or less. When the particle diameter of the conductive particle is the lower limit or more and the upper limit or less, the on-state reliability can be further improved even in the case of mounting in a short time.

[0164] The particle diameter of the conductive particle and the conductive filler is preferably the average particle diameter, and more preferably the number average particle diameter. In the case of the average particle diameter of the conductive particle and the conductive filler, for example, the average of the particle diameters of the respective conductive particles and the conductive filler is calculated by observing 50 arbitrary conductive particles and conductive fillers under an electron microscope or an optical microscope, or is found by performing laser diffraction particle size distribution measurement.

[0165] In the case where the particle diameter of the conductive particle is measured by a method of observing 50 arbitrary conductive particles under an electron microscope or an optical microscope, for example, it can be measured in the following manner. The conductive particle is added to "TECHNOVIT 4000" manufactured by Kulzer Co., Ltd. so as to be dispersed in a manner that the content of the conductive particle becomes 30% by weight, and an embedding resin body for conductive particle examination is prepared. An ion milling device ("IM 4000" manufactured by HITACHI HIGH-TECHNOLOGIES Co., Ltd.) is used in a manner that it passes through the vicinity of the center of the conductive particle dispersed in the embedding resin body for conductive particle examination, and a cross section of the conductive particle is cut out. Further, a field emission type scanning electron microscope (FE-SEM) is used, the image magnification is set to 25000 times, and 50 conductive particles are randomly selected and observed. The circle equivalent diameter of each conductive particle is measured, and the arithmetic average thereof is taken as the particle diameter of the conductive particle. The same applies to the conductive filler.

[0166] The coefficient of variation (CV value) of the particle diameter of the conductive particle is preferably 10% or less, and more preferably 5% or less. When the coefficient of variation of the particle diameter of the conductive particle is the upper limit or less, the on-state reliability can be further improved. The lower limit of the coefficient of variation (CV value) of the particle diameter of the conductive particle is not particularly limited. The coefficient of variation (CV value) of the particle diameter of the conductive particle can be 0% or more, and can be 1% or more.

[0167] The coefficient of variation (CV value) can be measured in the following manner.

[0168] CV value (%) = (p / Dn) x 100

[0169] p: standard deviation of the particle diameter of the conductive particle

[0170] Dn: average value of particle diameters of the conductive particles

[0171] The content of the conductive filler in 100% by weight of the conductive paste 100 is preferably 0.1% by weight or more, more preferably 1% by weight or more, further preferably 5% by weight or more, and preferably 80% by weight or less, more preferably 60% by weight or less, further preferably 50% by weight or less. When the content of the conductive filler is the lower limit or more and the upper limit or less, the on-state reliability can be further improved even in the case of installation in a short period of time.

[0172] The content of the conductive filler is preferably 2 parts by weight or more, more preferably 3 parts by weight or more, further preferably 5 parts by weight or more, and particularly preferably 7 parts by weight or more, with respect to 100 parts by weight of the content of the curable compound. The content of the conductive filler is preferably 35 parts by weight or less, more preferably 30 parts by weight or less, further preferably 25 parts by weight or less, and particularly preferably 20 parts by weight or less, with respect to 100 parts by weight of the content of the curable compound. When the content of the conductive filler is the lower limit or more and the upper limit or less, the on-state reliability can be further improved even in the case of installation in a short period of time.

[0173] The conductive filler preferably contains a metal. As the metal, for example, gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, ruthenium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, and alloys of these, and the like can be given. In addition, as the metal, tin-doped indium oxide (ITO) can be used. The metal can be used singly or in combination of two or more.

[0174] From the viewpoint of further reducing the connection resistance between electrodes, the conductive filler preferably contains an alloy containing tin, nickel, palladium, ruthenium, silver, copper, or gold, and more preferably contains nickel or palladium. From the viewpoint of improving the corrosion resistance of the conductive filler and maintaining a high on-state reliability, the conductive filler preferably contains nickel or gold, and more preferably contains nickel. From the viewpoint of improving the corrosion resistance of the conductive filler and maintaining a high on-state reliability, the conductive filler particularly preferably contains nickel on the outer surface.

[0175] In the case where the conductive particle is a metal particle, as the metal of the material of the metal particle, silver, copper, nickel, silicon, gold, titanium, and alloys such as solder, and the like can be given. From the viewpoint of further effectively improving the on-state reliability, the material of the metal particle preferably contains nickel or a nickel alloy, and more preferably the material of the metal particle is nickel or a nickel alloy. From the viewpoint of further effectively improving the on-state reliability, the outer surface portion of the metal particle preferably contains nickel or a nickel alloy.

[0176] Hereinafter, the details of the conductive particle having the base material particle and the conductive portion arranged on the surface of the base material particle will be described.

[0177] (Base material particle)

[0178] As the base material particle, resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles, etc. can be given. The base material particle is preferably a base material particle other than a metal particle, and more preferably a resin particle, an inorganic particle other than a metal particle, or an organic-inorganic hybrid particle. The base material particle can be a core-shell particle having a core and a shell arranged on the surface of the core. The core can be an organic core, and the shell can be an inorganic shell.

[0179] The base material particle is further preferably a resin particle or an organic-inorganic hybrid particle, and can be a resin particle or an organic-inorganic hybrid particle. By using these preferred base material particles, the effects of the present application can be further effectively exerted.

[0180] As the material of the resin particle, various resins are suitably used. As the material of the resin particle, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, polybutadiene, and the like polyolefin resins; polymethyl methacrylate, polymethyl acrylate, and the like acrylic resins; polyalkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol formaldehyde resin, melamine resin, benzoguanamine resin, urea formaldehyde resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene ether, polyacetal, polyimide, polyamide-imide, polyether ether ketone, polyether sulfone, divinylbenzene polymer, and a polymer obtained by polymerizing one or two or more kinds of various polymerizable monomers having multiple ethylenic unsaturated groups, and the like can be given. The divinylbenzene polymer can be a divinylbenzene-based copolymer. As the divinylbenzene-based copolymer, divinylbenzene-styrene copolymer, divinylbenzene-(meth)acrylate copolymer, and the like can be given.

[0181] From the aspect that it is possible to design and synthesize a resin particle having arbitrary compression characteristics suitable for a conductive paste, and to easily control the hardness of the resin particle within a suitable range, the material of the resin particle is preferably a polymer obtained by polymerizing one or two or more kinds of polymerizable monomers having multiple ethylenic unsaturated groups.

[0182] In the case where the resin particle is obtained by polymerizing a polymerizable monomer having an ethylenic unsaturated group, as the polymerizable monomer having an ethylenic unsaturated group, a non-crosslinking monomer and a crosslinking monomer can be given.

[0183] As the non-crosslinking monomer, styrene, α-methylstyrene, and the like styrene-based monomers; (meth)acrylic acid, maleic acid, maleic anhydride, and the like carboxyl group-containing monomers; methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and the like (meth)acrylate alkyl ester compounds; 2-hydroxyethyl (meth)acrylate, glyceryl (meth)acrylate, polyoxyethylene (meth)acrylate, glycidyl (meth)acrylate, and the like oxygen atom-containing (meth)acrylate compounds; (meth)acrylonitrile and the like nitrile-containing monomers; vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate, and the like acid vinyl ester compounds; ethylene, propylene, isoprene, butadiene, and the like unsaturated hydrocarbons; trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, chlorovinyl, fluorovinyl, chlorostyrene, and the like halogen-containing monomers, and the like can be given.

[0184] As the crosslinking monomer, tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and the like multifunctional (meth)acrylate compounds; triallyl (iso)cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, γ-(meth)acryloyloxypropyltrimethoxysilane, trimethoxysilylphenylethylene, vinyltrimethoxysilane, and the like silane-containing monomers, and the like can be given.

[0185] The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenic unsaturated group by a publicly known method. As the method, for example, a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of swelling a radical polymerization initiator together with a monomer using non-crosslinking seed particles, and the like can be given.

[0186] In the case where the base material particles are inorganic particles other than metal particles or organic-inorganic hybrid particles, as the inorganic substance of the material of the base material particles, there can be mentioned silica, alumina, barium titanate, zirconia, carbon black, and the like. The inorganic substance is preferably not a metal. As the particles formed by the silica, there is no particular limitation, and there can be mentioned, for example, particles obtained by forming crosslinked polymer particles by hydrolyzing a silicon compound having two or more hydrolytic alkoxy silyl groups, and, if necessary, firing the particles. As the organic-inorganic hybrid particles, there can be mentioned, for example, organic-inorganic hybrid particles formed by an alkoxysilyl polymer that has been crosslinked and an acrylic resin, and the like.

[0187] The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. From the viewpoint of further effectively reducing the connection resistance between electrodes, the base material particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

[0188] As the material of the organic core, there can be mentioned the material of the resin particles, and the like.

[0189] As the material of the inorganic shell, there can be mentioned the inorganic substance mentioned as the material of the base material particles. The material of the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a shell of a metal alkoxide on the surface of the core by a sol-gel method, and firing the shell. The metal alkoxide is preferably a silanol salt. The inorganic shell is preferably formed by a silanol salt.

[0190] In the case where the base material particles are metal particles, as the metal of the material of the metal particles, there can be mentioned silver, copper, nickel, silicon, gold, titanium, alloys such as solder, and the like.

[0191] The melting point of the metal particles is preferably more than 450°C, more preferably 500°C or higher, further preferably 600°C or higher, further preferably 700°C or higher, more further preferably 800°C or higher, and particularly preferably 900°C or higher. When the melting point of the metal particles is the lower limit or higher, the jetting stability of the conductive paste can be further improved. The melting point of the metal particles can be 3000°C or lower, or 2500°C or lower. The range of the melting point of the metal particles can be set by appropriately selecting the lower limit value and the upper limit value.

[0192] The particle diameter of the base material particle is preferably 0.01 μm or more, more preferably 0.05 μm or more, further preferably 0.5 μm or more, further preferably 1 μm or more, particularly preferably 3 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, further preferably 20 μm or less, particularly preferably 10 μm or less. When the particle diameter of the base material particle is the lower limit or more, the conduction reliability becomes higher. Further, when the electrically conductive portion is formed on the surface of the base material particle, agglomeration becomes less likely to occur, and agglomerated electrically conductive particles become less likely to be formed. When the particle diameter of the base material particle is the upper limit or less, the electrically conductive particles are easily sufficiently compressed, and the connection resistance between the electrodes connected by the electrically conductive particles can be further effectively reduced.

[0193] The particle diameter of the base material particle is preferably the average particle diameter, and more preferably the number average particle diameter. The number average particle diameter of the base material particle can be measured, for example, in the following manner. An embedding resin for base material particle examination is prepared by adding the base material particles to "TECHNOVIT 4000" manufactured by Kulzer Co., Ltd. so that the content of the electrically conductive particles becomes 30% by weight, and dispersing the same. A cross section of the electrically conductive particles is cut using an ion milling device (IM4000 manufactured by HITACHI HIGH-TECHNOLOGIES Co., Ltd.) so that the center of the base material particle in the electrically conductive particles dispersed in the embedding resin for base material particle examination is used as a reference. Further, using a field emission type scanning electron microscope (FE-SEM), the image magnification is set to 25000 times, and 50 electrically conductive particles are randomly selected, and the base material particles of each of the electrically conductive particles are observed. The particle diameters of the base material particles in each of the electrically conductive particles are measured, and the arithmetic average thereof is used as the average particle diameter of the base material particles.

[0194] (Electrically conductive portion)

[0195] The electrically conductive portion preferably contains a metal. The metal constituting the electrically conductive portion is not particularly limited. As the metal, for example, gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, ruthenium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, and alloys of these, and the like can be given. Further, as the metal, indium tin oxide (ITO) can be used. The metal can be used singly, or two or more kinds thereof can be used in combination. From the viewpoint of further reducing the connection resistance between the electrodes, an alloy containing tin, nickel, palladium, ruthenium, silver, copper, or gold is preferred, and nickel or palladium is more preferred.

[0196] From the viewpoint of further effectively improving the conduction reliability, it is preferred that the electrically conductive portion contain nickel, and it is more preferred that the outer surface portion of the electrically conductive portion contain nickel.

[0197] The content of nickel in the conductive section 100 containing nickel is preferably 10% by weight or more, more preferably 50% by weight or more, further preferably 60% by weight or more, further preferably 70% by weight or more, and particularly preferably 90% by weight or more. The content of nickel in the conductive section 100 containing nickel can be 99% by weight or less, can be 90% by weight or less, or can be 70% by weight or less.

[0198] The conductive section can be formed of one layer. The conductive section can be formed of multiple layers. That is, the conductive section can have a laminated structure of two or more layers. In the case where the conductive section is formed of multiple layers, the metal constituting the outermost layer is preferably gold, silver, nickel, palladium, ruthenium, copper, or an alloy containing tin, and more preferably nickel. In the case where the metal constituting the outermost layer is one of these preferred metals, the connection resistance between electrodes is further reduced.

[0199] The method of forming the conductive section on the surface of the base material particle is not particularly limited. As the method of forming the conductive section, for example, methods based on electroless plating, electroplating, physical collision, mechanical chemical reaction, physical vapor deposition or physical adsorption, and methods of applying metal powder or a paste containing metal powder and a binder to the surface of the base material particle can be given. The method of forming the conductive section is preferably a method based on electroless plating, electroplating, or physical collision. As the method based on physical vapor deposition, methods such as vacuum evaporation, ion plating, and ion sputtering can be given. In addition, in the method based on physical collision, for example, a THETA COMPOSER (manufactured by TOKUJU Corporation) or the like is used.

[0200] The thickness of the conductive section is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 10 μm or less, more preferably 1 μm or less, and further preferably 0.3 μm or less. When the thickness of the conductive section is the lower limit or more and the upper limit or less, sufficient conductivity can be obtained, and the conductive particles do not become too hard, and the conductive particles can be sufficiently deformed at the time of connection.

[0201] In the case where the conductive section is formed of multiple layers, the thickness of the outermost layer of the conductive section is preferably 0.001 μm or more, more preferably 0.01 μm or more, and preferably 0.5 μm or less, more preferably 0.1 μm or less. When the thickness of the outermost layer of the conductive section is the lower limit or more and the upper limit or less, the outermost layer of the conductive section becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between electrodes can be sufficiently reduced.

[0202] The thickness of the conductive section can be measured, for example, by observing the cross section of the conductive particles using a transmission electron microscope (TEM).

[0203] Core substance:

[0204] The conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. The surface of the electrode connected by the conductive particles is formed with an oxide film. In the case where the conductive particles having protrusions on the outer surface of the conductive portion are used, the oxide film can be effectively removed by disposing the conductive particles between the electrodes and performing compression. Thus, the electrodes are further reliably in contact with the conductive portion, and the connection resistance between the electrodes is further reduced. Further, at the time of connection between the electrodes, the filler between the conductive particles and the electrodes can be effectively removed by the protrusions of the conductive particles. Thus, the conduction reliability between the electrodes becomes higher.

[0205] As a method of forming the protrusions, there are a method of attaching a core substance to the surface of the base material particles and then forming a conductive portion by electroless plating, a method of forming a conductive portion on the surface of the base material particles by electroless plating and then attaching a core substance and further forming a conductive portion by electroless plating, and the like. Further, in order to form the protrusions, a method of forming a conductive portion on the base material particles by electroless plating and then depositing plating in a protrusion shape on the surface of the conductive portion without using the core substance and further forming a conductive portion by electroless plating, and the like can be used.

[0206] As a method of attaching a core substance to the surface of the base material particles, there are a method of adding a core substance to a dispersion liquid of the base material particles and causing the core substance to be attached by aggregation on the surface of the base material particles by van der Waals force, a method of adding a core substance to a container in which the base material particles are contained and causing the core substance to be attached to the surface of the base material particles by mechanical action based on rotation of the container, and the like. From the viewpoint of controlling the amount of the attached core substance, the method of attaching a core substance to the surface of the base material particles is preferably a method of causing a core substance to be attached by aggregation on the surface of the base material particles in a dispersion liquid.

[0207] As a substance constituting the core substance, there are a conductive substance and a non-conductive substance. As the conductive substance, there are, for example, a metal, an oxide of a metal, a conductive non-metal such as graphite, and a conductive polymer, and the like. As the conductive polymer, there are, for example, polyacetylene, and the like. As the non-conductive substance, there are, for example, silicon dioxide, aluminum oxide, titanium oxide, tungsten carbide, and zirconium oxide, and the like. From the viewpoint of further improving the conduction reliability between the electrodes, the core substance is preferably a metal.

[0208] The metal is not particularly limited. As the metal, for example, metals such as gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, and alloys composed of two or more metals such as tin-lead alloy, tin-copper alloy, tin-silver alloy, tin-lead-silver alloy, and tungsten carbide, and the like can be given. From the viewpoint of further improving the conduction reliability between electrodes, the metal is preferably nickel, copper, silver, or gold. The metal can be the same as or different from the metal that constitutes the conductive portion.

[0209] The shape of the core substance is not particularly limited. The shape of the core substance is preferably a block. As the core substance, for example, a particle-like block, an agglomerated block in which a plurality of fine particles are agglomerated, and an amorphous block, and the like can be given.

[0210] The particle diameter of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, and is preferably 0.9 μm or less, more preferably 0.2 μm or less. When the particle diameter of the core substance is the lower limit or more and the upper limit or less, the connection resistance between electrodes can be effectively reduced.

[0211] The particle diameter of the core substance is preferably an average particle diameter, more preferably a number average particle diameter. As the particle diameter of the core substance, for example, by observing 50 arbitrary core substances under an electron microscope or an optical microscope, calculating the average of the particle diameters of the respective core substances, or performing laser diffraction type particle size distribution measurement, it is obtained.

[0212] <Non-conductive filler>

[0213] The conductive paste preferably further contains a non-conductive filler. The non-conductive filler is a filler that does not have conductivity.

[0214] As the non-conductive filler, for example, silicon dioxide, titanium dioxide, aluminum oxide, sorbitol, and zinc oxide, and the like can be given. The non-conductive filler can be used only one kind, or two or more kinds can be used in combination.

[0215] From the viewpoint of further improving the storage stability, the non-conductive filler preferably contains titanium dioxide, silicon dioxide, or aluminum oxide, more preferably contains silicon dioxide or titanium dioxide, and further preferably contains titanium dioxide.

[0216] From the viewpoint of further improving the storage stability, the non-conductive filler is preferably a solid at 25°C. From the viewpoint of further improving the storage stability, the non-conductive filler is preferably dispersed in the conductive paste.

[0217] When the non-conductive filler is a solid at 25°C, the particle diameter of the non-conductive filler is preferably 0.001 μm or more, more preferably 0.01 μm or more, further preferably 0.1 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less, further preferably 1 μm or less. When the particle diameter of the non-conductive filler is the lower limit or more and the upper limit or less, the storage stability can be further improved.

[0218] The particle diameter of the non-conductive filler is preferably the average particle diameter, and more preferably the number average particle diameter. In the case of the average particle diameter of the non-conductive filler, for example, the average value of the particle diameters of the respective non-conductive fillers is calculated by observing 50 arbitrary non-conductive fillers under an electron microscope or an optical microscope, or is found by performing laser diffraction type particle size distribution measurement.

[0219] The ratio of the particle diameter of the non-conductive filler to the particle diameter of the conductive filler (particle diameter of non-conductive filler / particle diameter of conductive filler) is preferably 0.0002 or more, more preferably 0.002 or more, further preferably 0.02 or more, and is preferably 0.5 or less, more preferably 0.1 or less, further preferably 0.05 or less. When the ratio (particle diameter of non-conductive filler / particle diameter of conductive filler) is the lower limit or more and the upper limit or less, the storage stability can be further improved.

[0220] The content of the non-conductive filler in the conductive paste 100% by weight is preferably 0.1% by weight or more, more preferably 0.3% by weight or more, and is preferably 10% by weight or less, more preferably 5% by weight or less. When the content of the non-conductive filler is the lower limit or more and the upper limit or less, the storage stability can be further improved.

[0221] The total content of the conductive filler and the non-conductive filler in the conductive paste 100% by weight is preferably 10% by weight or more, more preferably 15% by weight or more, and is preferably 40% by weight or less, more preferably 30% by weight or less. When the total content of the conductive filler and the non-conductive filler is the lower limit or more and the upper limit or less, the storage stability can be further improved.

[0222] <Chelating agent>

[0223] The conductive paste preferably further contains a chelating agent. The chelating agent is preferably used in combination with the amine curing agent. The chelating agent, by being used in combination with the amine curing agent, can protect the surface of the amine curing agent, further improving the storage stability of the conductive paste.

[0224] As the chelating agent, boric acid ester, barbituric acid, and isophthalic acid, and the like can be given. The chelating agent can be used alone or two or more kinds can be used in combination.

[0225] From the viewpoint of further improving the storage stability, the chelating agent preferably contains a borate ester, more preferably tributyl borate.

[0226] The content of the chelating agent in the conductive paste 100 is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, particularly preferably 0.2% by weight or more, and preferably 10% by weight or less, more preferably 5% by weight or less. When the content of the chelating agent is the lower limit or more and the upper limit or less, the storage stability can be further improved.

[0227] The content of the chelating agent is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, with respect to 100 parts by weight of the content of the amine curing agent, and is preferably 100 parts by weight or less, more preferably 50 parts by weight or less. When the content of the chelating agent is the lower limit or more and the upper limit or less, the storage stability can be further improved.

[0228] <Other components>

[0229] The conductive paste can contain components other than the curable compound, the curing agent, the conductive filler, the non-conductive filler, and the chelating agent. As the other components, solvents, inorganic fillers, organic fillers, colorants, polymerization inhibitors, chain transfer agents, antioxidants, ultraviolet absorbers, defoaming agents, leveling agents, surfactants, slip agents, anti-blocking agents, waxes, masking agents, odor-masking agents, fragrances, preservatives, antibacterial agents, antistatic agents, and adhesion-imparting agents, etc. can be contained as the other components.

[0230] (RFID inlay and method for manufacturing RFID inlay)

[0231] The RFID inlay of the present application is provided with a substrate having a wiring on a surface, a chip having an electrode on a surface, and a bonding portion that bonds the substrate and the chip. In the RFID inlay of the present application, the material of the bonding portion is the conductive paste (the first conductive paste or the second conductive paste). In the RFID inlay of the present application, the wiring and the electrode are electrically connected by the conductive filler in the bonding portion.

[0232] Figure 1 is a cross-sectional view schematically showing an RFID inlay using the conductive paste of the first embodiment of the present application.

[0233] Figure 1The RFID inlay 81 is provided with a substrate 82 having a wiring on a surface, a chip 83 having an electrode on a surface, and an adhesive portion 84 that adheres the substrate 82 and the chip 83. The adhesive portion 84 is made of a conductive paste containing the conductive filler 1. The adhesive portion 84 is formed by curing the conductive paste containing the conductive filler 1.

[0234] The substrate 82 has a wiring 82a on a surface (upper surface). The chip 83 has an electrode 83a on a surface (lower surface). The wiring 82a and the electrode 83a are electrically connected by the conductive filler 1 in the adhesive portion 84.

[0235] The manufacturing method of the RFID inlay of the present application includes the following (1) to (3). (1) A first placement step of placing the conductive paste (first conductive paste or second conductive paste) on a surface of a substrate having a wiring on a surface. (2) A second placement step of placing a chip having an electrode on a surface on a surface of the conductive paste opposite to the substrate side. (3) An adhering step of forming an adhesive portion that adheres the substrate and the chip from the conductive paste by heating and pressing the conductive paste, and electrically connecting the wiring and the electrode by the conductive filler in the adhesive portion.

[0236] The RFID inlay and the manufacturing method of the RFID inlay of the present application can improve the adhesion of the substrate and the chip and improve the conduction reliability because a specific conductive paste is used.

[0237] In the manufacturing method of the RFID inlay, the substrate is preferably in a long strip shape, and the RFID inlay is manufactured by feeding the long strip-shaped substrate in a roll-to-roll manner in the first placement step, the second placement step, and the adhering step. In this case, a plurality of RFID inlays can be continuously manufactured, and the manufacturing efficiency of the RFID inlay can be further improved.

[0238] In the case of using the roll-to-roll manner, the feeding speed of the substrate is not particularly limited.

[0239] As a method of placing the conductive paste, for example, a dispenser-based coating, screen printing, and inkjet device-based ejection can be given.

[0240] The heating temperature in the adhering step is preferably 100°C or higher, more preferably 150°C or higher, and is preferably 400°C or lower, more preferably 300°C or lower, and further preferably 250°C or lower. When the heating temperature in the adhering step is the lower limit or higher and the upper limit or lower, the electrical connection between the chip and the substrate can be improved.

[0241] The pressure in the bonding step is preferably 0.5 N or more, more preferably 1 N or more, preferably 3.5 N or less, more preferably 3 N or less, and further preferably 2.5 N or less. When the pressure in the bonding step is the lower limit or more and the upper limit or less, the adhesion of the substrate to the chip can be improved, and the conduction reliability can be improved.

[0242] The heating and pressure time in the bonding step is not particularly limited. The heating and pressure time in the bonding step can be 2 seconds or more, can be 15 seconds or less, can be 10 seconds or less, can be 9 seconds or less, or can be 7 seconds or less.

[0243] The RFID inlay can be cut to a given size as needed, or can be used as cut. Preferably, a plurality of the chips are bonded to the substrate in a long strip shape by a plurality of the bonding portions. On the substrate in a long strip shape, a plurality of the chips and the laminates of the bonding portions can be arranged. In the first arrangement step, the conductive paste is preferably arranged at a plurality of positions on the surface of the substrate in a long strip shape. In the second arrangement step, the chip is preferably arranged on the surface opposite to each of the substrate side using a plurality of chips arranged on the conductive paste at a plurality of positions. The substrate in a long strip shape can be cut after the chip is bonded to the substrate in a long strip shape by the bonding portion.

[0244] The substrate is not particularly limited. The substrate is preferably a circuit substrate. As the circuit substrate, a resin film, a flexible printed substrate, a rigid flexible substrate, a glass substrate, a paper substrate, and the like can be given. The substrate can be a resin substrate, can be a glass substrate, or can be a paper substrate.

[0245] The substrate has a wiring (antenna pattern) on the surface. The wiring (antenna pattern) is formed on the surface of the base material. The substrate preferably has a base material and a wiring (antenna pattern) arranged on the surface of the base material.

[0246] As the material of the base material, a resin, glass, paper, and the like can be given. As the resin, PET (polyethylene terephthalate), PP (polypropylene), PVC (polyvinyl chloride), and the like can be given. In the case of the paper, an epoxy resin or a phenol resin can be impregnated. From the viewpoint of further improving the adhesion and the viewpoint of manufacturing the RFID inlay by a roll-to-roll method, the material of the base material is preferably a resin or paper, and more preferably PET (polyethylene terephthalate) or paper. The base material can be a resin, can be glass, or can be paper.

[0247] As the wiring (antenna pattern), a gold wiring, a nickel wiring, a tin wiring, an aluminum wiring, a silver wiring, a SUS wiring, a copper wiring, a molybdenum wiring, and a tungsten wiring, and the like can be exemplified. From the viewpoint of improving the action sensitivity in the UHF band (860 MHz to 960 MHz), the wiring is preferably an aluminum wiring.

[0248] From the viewpoint of suppressing the deformation of the substrate caused by heat at the time of mounting the chip (for example, an IC chip), and improving the flexibility, the thickness of the substrate is preferably 20 μm or more, more preferably 30 μm or more, and is preferably 200 μm or less, more preferably 100 μm or less.

[0249] The shape of the substrate and the base material is not particularly limited. From the viewpoint of manufacturing the RFID inlay by a roll-to-roll method, the substrate and the base material are preferably in a long strip shape. The length of the substrate and the base material is not particularly limited. The length of the substrate and the base material can be 1 m or more, can be 10 m or more, can be 5000 m or less, and can be 1000 m or less.

[0250] As the chip, a semiconductor chip (IC chip), and the like can be exemplified.

[0251] The chip has an electrode on the surface. As the electrode, a metal electrode such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a silver electrode, a SUS electrode, a copper electrode, a molybdenum electrode, and a tungsten electrode can be exemplified. From the viewpoint of further improving the conduction reliability, the electrode is preferably a copper electrode or a gold electrode, and more preferably a copper electrode.

[0252] The number of the electrodes per 1 chip is not particularly limited. The number of the electrodes per 1 chip can be 1 or more, can be 4 or more, can be 20 or less, and can be 10 or less.

[0253] The shape of the chip is not particularly limited. The shape of the chip can be a rectangular shape, can be a triangular shape, and can be a circular shape.

[0254] The planar area of the chip is preferably 0.04 mm 2 and more preferably 0.09 mm 2 and further preferably 0.16 mm 2 and preferably 0.50 mm 2 and more preferably 0.40 mm 2 and further preferably 0.30 mm 2The lower limit is the lower limit of the planar area of the chip. The upper limit is the upper limit of the planar area of the chip. When the planar area of the chip is equal to or greater than the lower limit, the conductive paste can be disposed on the fine wiring with high precision. When the planar area of the chip is equal to or less than the upper limit, the RFID inlay can maintain the conduction reliability even when left for a long time in a high-temperature and high-humidity environment. The conductive paste of the present application can be suitably used for the adhesion of a relatively small chip.

[0255] Hereinafter, the present application will be specifically described by citing examples and comparative examples. The present application is not limited to the following examples.

[0256] The following materials were prepared.

[0257] Curing compound:

[0258] "EP-3950S" (glycidyl amine type epoxy compound) manufactured by ADEKA Corporation

[0259] "EP-3980S" (glycidyl amine type epoxy compound) manufactured by ADEKA Corporation

[0260] "EXA830CRP" (bisphenol F type epoxy compound) manufactured by DIC Corporation

[0261] "EXA850CRP" (bisphenol A type epoxy compound) manufactured by DIC Corporation

[0262] Curing agent:

[0263] "Karenz MT PE-1" (secondary thiol curing agent having an ester skeleton) manufactured by RESONAC Corporation

[0264] "TMMP" (primary thiol curing agent having an ester skeleton) manufactured by SC Organic Chemicals Corporation

[0265] "AJICURE PN23" (amine adduct curing agent, solid at 25°C) manufactured by AJINOMOTO FINE-TECHNO Corporation

[0266] "Divinyltriamine" (amine curing agent, liquid at 25°C) manufactured by TCI Corporation

[0267] "TS-G" (primary thiol curing agent not having an ester skeleton) manufactured by SHIKOKU KAGAKU KOGYO Corporation

[0268] "C3TS-G" (primary thiol curing agent not having an ester skeleton) manufactured by SHIKOKU KAGAKU KOGYO Corporation

[0269] "PEMP" (primary thiol curing agent having an ester skeleton) manufactured by SAKAI CHEMICAL INDUSTRY Corporation

[0270] "NOVACURE HX4922HP" (microcapsule type curing agent) manufactured by Asahi Kasei E-Materials Co., Ltd.

[0271] Conductive filler:

[0272] "CN050" (nickel particle, average particle diameter: 5 μm) manufactured by NIKKO-RICA Co., Ltd.

[0273] "NIB-205-S" (conductive particle having resin particles and a conductive layer disposed on the surface of the resin particles, average particle diameter: 5 μm) manufactured by Shikoku Chemicals Corporation

[0274] Non-conductive filler:

[0275] "RX-200" (silicon dioxide, solid at 25°C, average particle diameter: 0.012 μm) manufactured by Nippon Aerosil Co., Ltd.

[0276] "GEL ALL D" (sorbitol (thixotropic agent), solid at 25°C, average particle diameter: 0.10 μm) manufactured by Shin Nippon Rika Co., Ltd.

[0277] Chelating agent:

[0278] "tributyl borate" manufactured by TCI Co., Ltd.

[0279] Thixotropic agent (non-conductive filler):

[0280] "GEL ALL D" (sorbitol, solid at 25°C, average particle diameter: 0.10 μm) manufactured by Shin Nippon Rika Co., Ltd.

[0281] Chip:

[0282] IC chip (copper electrode, "UCODE9" manufactured by NXP Co., Ltd., planar area: 0.22 mm 2 )

[0283] Substrate:

[0284] PET film (long strip, resin film having an aluminum wiring with a motion frequency of the UHF band (860 MHz to 960 MHz))

[0285] (Example 1)

[0286] (1) Preparation of conductive paste

[0287] The materials shown in Table 1 below were mixed in the amounts (parts by weight) shown in Table 1 below, and stirring was performed using a planetary stirring device ("AWATORI Rentaro" manufactured by THINKY Co., Ltd.), to obtain a conductive paste (anisotropic conductive paste).

[0288] (2) Preparation of RFID inlay

[0289] The obtained conductive paste was coated on a PET film by a jet dispensing method to form a conductive paste layer (adhesive portion layer) (1st arrangement step). Next, an IC chip was laminated on the surface of the conductive paste layer (adhesive portion layer) opposite to the substrate side in such a manner that the wiring on the surface of the PET film and the electrode on the surface of the chip face each other (2nd arrangement step). Then, heat press bonding was performed under conditions of an upper heating tool of 180°C, a lower heating tool of 180°C, a pressure of 2 N, and a press bonding time of 3 seconds to cure the conductive paste layer (adhesive portion layer) to form an adhesive portion. Further, the wiring on the surface of the PET film and the electrode on the surface of the chip were electrically connected by the conductive filler (conductive particles) in the adhesive portion to obtain a connection structure (adhesion step). Note that the 1st arrangement step, the 2nd arrangement step, and the adhesion step were performed using "DDA40000" (roll-to-roll system) manufactured by Muhlbauer. The obtained connection structure was cut into a size of 5 cm x 1.5 cm using "DCL30000" manufactured by Muhlbauer to obtain 50 RFID inlays.

[0290] (Examples 2 to 12 and Comparative Examples 1 to 6)

[0291] The conductive paste and the RFID inlay were obtained in the same manner as in Example 1 except that the components and the amounts of the conductive paste were changed in the manners shown in Tables 1, 3, 5, 7, and 9.

[0292] (Evaluation)

[0293] (1) Differential Scanning Calorimetry

[0294] A differential scanning calorimetry device (TA7000 manufactured by HITACHI HIGH-TECH SCIENCE) was prepared, and 5 mg of the obtained conductive paste was taken in a dedicated aluminum pan, and the lid was closed using a dedicated jig. The dedicated aluminum pan and an empty aluminum pan (control) were set in a heating device, and observation of the reversible heat flow and the irreversible heat flow was performed at a temperature increase rate of 10°C / minute from 30°C to 200°C in an air atmosphere. The exothermic peak observed in the irreversible heat flow was taken as the exothermic peak of the conductive paste, and the exothermic start temperature, the exothermic peak top temperature, and the exothermic end temperature were calculated.

[0295] (2) Storage stability (pot life)

[0296] For the freshly prepared conductive paste, the viscosity at 25°C (η25) was measured by the method. In addition, the viscosity at 25°C (ηa) of the conductive paste after storage at 25°C and 50% RH for 24 hours was measured by the method. The ratio of the viscosity after storage (ηa) to the viscosity of the freshly prepared paste (η25) was calculated (viscosity after storage (ηa) / viscosity of the freshly prepared paste (η25)), and the storage stability (pot life) was determined according to the following criteria.

[0297] [Criteria for determining the storage stability (pot life)]

[0298] O: The ratio of the viscosity after storage to the viscosity of the freshly prepared paste is 1.1 or more and less than 1.25

[0299] O: The ratio of the viscosity after storage to the viscosity of the freshly prepared paste is 1.1 or more and less than 1.25

[0300] X: The ratio of the viscosity after storage to the viscosity of the freshly prepared paste is 1.25 or more

[0301] (3) Curing property of the conductive paste

[0302] (3-1) Curing property of the conductive paste (low-temperature rapid curing property)

[0303] The conductive paste was coated on a glass plate at a thickness of 30 μm. The glass plate was placed on the surface of a hot plate from the surface opposite to the side on which the paste was coated, and the temperature at which the conductive paste was gelled (cured) within 3 seconds was measured. The curing property (low-temperature rapid curing property) of the conductive paste was determined according to the following criteria. Note that, after heating for 3 seconds, the use of a needle with a handle was used to confirm the presence or absence of a wire, and in the case where the wire was not cut, it was determined that the conductive paste had been cured.

[0304] [Criteria for determining the curing property (low-temperature rapid curing property) of the conductive paste]

[0305] A: The temperature at which the conductive paste was cured was less than 160°C

[0306] B: The temperature at which the conductive paste was cured was 160°C or more and less than 200°C

[0307] C: The temperature at which the conductive paste was cured was 200°C or more or not cured

[0308] (3-2) Curing property of the conductive paste (gelation time)

[0309] The conductive paste was applied on a glass plate at a thickness of 30 μm. The glass plate was placed on the surface of a hot plate (set temperature 180°C) from the surface opposite to the side on which the conductive paste was applied, and the elapsed time until the conductive paste gelled was measured. The curing property (gel time) of the conductive paste was judged according to the following criteria. Note that the wire drawing was confirmed every 5 seconds using a needle with a handle, and when the wire was not cut, it was judged that the conductive paste had gelled.

[0310] [Criteria for judging the curing property (gel time) of the conductive paste]

[0311] O O O O: Conductive: elapsed time until the paste gelled was less than 5 seconds

[0312] O O O: elapsed time until the conductive paste gelled was 5 seconds or more and less than 10 seconds

[0313] O O: elapsed time until the conductive paste gelled was 10 seconds or more and less than 15 seconds

[0314] O: elapsed time until the conductive paste gelled was 15 seconds or more and less than 30 seconds

[0315] X: elapsed time until the conductive paste gelled was 30 seconds or more

[0316] (4) Adhesiveness (Chip Shear Strength)

[0317] For the obtained RFID inlay, the chip shear strength at 25°C was evaluated using a chip shear tester (NORDSON Corporation "DAGE 4000 PLUS") under conditions of a tool height of 30 μm and a speed of 100 μm / sec, by peeling the chip from the substrate. The adhesiveness was judged according to the following criteria.

[0318] [Criteria for judging the adhesiveness]

[0319] O O: chip shear strength was 7.0 N or more

[0320] O: chip shear strength was 4.0 N or more and less than 7.0 N

[0321] X: chip shear strength was less than 4.0 N

[0322] (5) Stickiness of the Cured Product

[0323] Fill a PTFE mold with the prepared conductive paste. Heat the paste in an oven at 180°C for 300 seconds to obtain a 5 mm x 40 mm x 2 mm strip of solidified material. Allow the resulting solidified material to stand at room temperature for at least 12 hours and then cool. At 25°C, touch one end of the solidified material with the tip of a needle handle to observe whether the solidified material warps. The viscosity of the solidified material is determined according to the following criteria.

[0324] [Criteria for Determining Viscosity of Cured Material]

[0325] ○○: Cured product does not warp

[0326] ○: The other end of the needle with the handle is not in contact with the ground, and one end of the solidified material is raised

[0327] ×: The entire cured product is warped

[0328] (6) Conductivity reliability

[0329] Fifty of the resulting RFID inlays were conditioned at 85°C and 85% RH (high temperature, high humidity) for 168 hours. The inlays were then placed in a dark box shielded from external radio waves. Peak sensitivity at 25°C in the UHF band (860 MHz to 960 MHz) was measured using a frequency reader (Voyantic's "Tagformance Pro"). Conductivity reliability was assessed using the following criteria.

[0330] [Criteria for determining conduction reliability]

[0331] ○○: Peak sensitivity of all RFID inlays is less than -18dBm

[0332] ○: Does not belong to either ○○ or ×

[0333] ×: At least one RFID inlay has a peak sensitivity of -16.4dBm or higher

[0334] The compositions of the conductive pastes and the results are shown in Tables 1 to 10 below.

[0335] [Table 1]

[0336]

[0337] [Table 2]

[0338]

[0339] [Table 3]

[0340]

[0341] [Table 4]

[0342]

[0343] [Table 5]

[0344]

[0345] [Table 6]

[0346]

[0347] [Table 7]

[0348]

[0349] [Table 8]

[0350]

[0351] [Table 9]

[0352]

[0353] [Table 10]

[0354]

[0355] Explanation of symbols

[0356] 1 … electrically conductive filler

[0357] 81 … RFID inlay

[0358] 82 … substrate having a wiring on a surface

[0359] 82a … wiring

[0360] 83 … chip having an electrode on a surface

[0361] 83a … electrode

[0362] 84 … adhesive portion

Claims

1. A conductive paste, which is a conductive paste containing a curable compound, a curing agent, and a conductive filler, wherein when differential scanning calorimetry is performed on the conductive paste by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the exothermic onset temperature is 50°C or higher and 80°C or lower.

2. A conductive paste, which is a conductive paste containing a curable compound, a curing agent, and a conductive filler, wherein the curing agent contains a secondary thiol curing agent or a primary thiol curing agent having no ester skeleton, the conductive filler is a conductive particle having a resin particle and a conductive layer disposed on the surface of the resin particle, or a metal particle having a melting point of more than 450°C.

3. The conductive paste according to claim 1 or 2, wherein the curable compound contains a glycidyl amine type epoxy compound.

4. The conductive paste according to any one of claims 1 to 3, wherein the curing agent contains a thiol curing agent having two or more thiol groups.

5. The conductive paste according to any one of claims 1 to 4, wherein the curing agent contains a thiol curing agent having a structure represented by the following formula (1), [Chemical Formula 1] ， in the formula (1), R1, R2, R3, and R4 each represent an alkylene group having 1 to 5 carbon atoms.

6. The conductive paste according to any one of claims 1 to 5, wherein the curing agent contains a secondary thiol curing agent or a primary thiol curing agent having no ester skeleton, the content of the total of the secondary thiol curing agent and the primary thiol curing agent having no ester skeleton is 5% by weight or more and 50% by weight or less in 100% by weight of the conductive paste.

7. The conductive paste according to any one of claims 1 to 6, wherein the curing agent contains a secondary thiol curing agent.

8. The conductive paste according to any one of claims 1 to 7, wherein when differential scanning calorimetry is performed on the conductive paste by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the exothermic end temperature is 85°C or higher and 180°C or lower.

9. The conductive paste according to any one of claims 1 to 8, wherein when differential scanning calorimetry is performed on the conductive paste by heating from 30°C to 200°C at a temperature increase rate of 10°C / minute, the absolute value of the difference between the exothermic onset temperature and the exothermic end temperature is 5°C or higher and 100°C or lower.

10. The conductive paste according to any one of claims 1 to 9, wherein the curing agent contains a microcapsule type curing agent.

11. The conductive paste according to claim 10, wherein the content of the microcapsule type curing agent is 5% by weight or more and 40% by weight or less in 100% by weight of the conductive paste.

12. The conductive paste according to any one of claims 1 to 11, wherein the particle diameter of the conductive filler is 10 μm or less.

13. The conductive paste according to any one of claims 1 to 12, wherein the content of the conductive filler is 0.1% by weight or more and 50% by weight or less in 100% by weight of the conductive paste.

14. The conductive paste according to any one of claims 1 to 13, wherein the curing agent contains an amine curing agent that is a solid at 25°C.

15. The conductive paste according to any one of claims 1 to 14, further comprising a chelating agent.

16. The conductive paste according to claim 15, wherein the chelating agent comprises a borate ester.

17. The conductive paste according to any one of claims 1 to 16, further comprising a non-conductive filler.

18. The conductive paste according to claim 17, wherein a ratio of a particle size of the non-conductive filler to a particle size of the conductive filler is 0.5 or less.

19. The conductive paste according to any one of claims 1 to 18, which is used for obtaining an RFID inlay.

20. An RFID inlay comprising: a substrate having a wiring on a surface thereof, a chip having an electrode on a surface thereof, and a bonding portion in which the substrate and the chip are bonded to each other, a material of the bonding portion is the conductive paste according to any one of claims 1 to 19, the wiring and the electrode are electrically connected to each other via the conductive filler in the bonding portion.

21. A method for manufacturing an RFID inlay, comprising: a first disposing step of disposing the conductive paste according to any one of claims 1 to 19 on a surface of a substrate having a wiring on a surface thereof; a second disposing step of disposing a chip having an electrode on a surface thereof on a surface of the conductive paste opposite to the substrate; and a bonding step of forming a bonding portion in which the substrate and the chip are bonded to each other from the conductive paste by heating and pressing the conductive paste, and electrically connecting the wiring and the electrode to each other via the conductive filler in the bonding portion.

22. The method for manufacturing an RFID inlay according to claim 21, wherein the substrate is in a long strip shape, in the first disposing step, the second disposing step, and the bonding step, the long strip-shaped substrate is transported by a roll-to-roll method to manufacture the RFID inlay.

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