Conductive paste, RFID inlay, method for manufacturing RFID inlay, use of conductive paste for bonding chips, and use of conductive paste for obtaining RFID inlay

Abstract

The present invention provides a conductive paste which is capable of increasing bondability and is also capable of increasing conduction reliability.　A conductive paste according to the present invention contains a curable compound, a plurality of conductive particles and a thermal polymerization initiator; the curable compound contains a urethane (meth)acrylate which has a molecular weight of 1,000 or more, while having an aromatic skeleton, and a polymerizable monomer which has a molecular weight of less than 1,000, while having an aromatic skeleton or an alicyclic skeleton; and the viscosity of the conductive paste at 25°C is 5 Pa∙s to 50 Pa∙s.

Description

[Technical Field]

[0001] The present invention relates to a conductive paste containing conductive particles, an RFID inlay using the conductive paste, and a method for manufacturing an RFID inlay. The present invention also relates to the use of the conductive paste for bonding chips and the use of the conductive paste for obtaining an RFID inlay. [Background technology]

[0002] RFID (Radio Frequency Identification) inlays, which enable contactless data transmission and reception, are widely used in contactless RFID tags, contactless RFID cards, etc. In particular, UHF (Ultra High Frequency) band (860 MHz to 960 MHz) RFID inlays have attracted attention due to their long communication distances, and UHF band RFID inlays are used for a variety of items and purposes, such as commuter passes, inventory management, distribution management, and history management.

[0003] In RFID inlays, a conductive paste containing conductive particles and a binder resin is sometimes used to bond and connect a chip having electrodes on its surface to a substrate having wiring (antenna pattern) on its surface.

[0004] In recent years, as electronic components using RFID inlays have become smaller, the chips used in RFID inlays have also become smaller, creating a demand for conductive pastes that have high adhesive properties and can be placed on wiring with even greater precision.

[0005] Patent Document 1 listed below discloses an adhesive applicable to electronic components. The adhesive is an acrylic adhesive composition containing a radical initiator having a 10-hour half-life temperature of 80°C or less, a vinylene-containing oligomer, and at least one diluent. The adhesive can be snap-cured at low temperatures, and has a usable life of 24 hours or more at room temperature. Patent Document 1 describes urethane acrylate as an example of the vinylene-containing oligomer.

[0006] Patent Document 2 below discloses a conductive adhesive containing a polymerizable acrylic compound, an organic peroxide, and solder particles, in which the one-minute half-life temperature of the organic peroxide is lower than the solidus temperature of the solder particles. Patent Document 2 also describes urethane acrylate as an example of the polymerizable acrylic compound. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-144018 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-124330 Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional adhesives (conductive pastes) such as those described in Patent Documents 1 and 2 can improve adhesiveness to a certain extent. However, because the viscosity of urethane (meth)acrylate is relatively high, the viscosity of conductive pastes containing urethane (meth)acrylate also increases, making it difficult to precisely position the conductive paste on fine wiring. As a result, it can be difficult to improve the electrical conductivity reliability of the resulting electronic components. Furthermore, when a low-viscosity material is added to urethane (meth)acrylate to lower the viscosity, the urethane (meth)acrylate and the low-viscosity material may not mix uniformly, resulting in reduced electrical conductivity reliability.

[0009] Furthermore, with conventional conductive pastes, if the connection structure after conductive connection is left in a high-temperature, high-humidity environment for a long period of time (for example, 500 hours), the electrical conductivity reliability may decrease.

[0010] An object of the present invention is to provide a conductive paste that can improve adhesiveness and conduction reliability. Another object of the present invention is to provide an RFID inlay using the conductive paste and a method for manufacturing an RFID inlay. [Means for solving the problem]

[0011] According to a broad aspect of the present invention, there is provided a conductive paste comprising a curable compound, a plurality of conductive particles, and a thermal polymerization initiator, wherein the curable compound comprises a urethane (meth)acrylate having a molecular weight of 1000 or more and having an aromatic skeleton, and a polymerizable monomer having a molecular weight of less than 1000 and having an aromatic skeleton or an alicyclic skeleton, and the viscosity of the conductive paste at 25°C is 5 Pa s or more and 50 Pa s or less.

[0012] In a specific aspect of the conductive paste according to the present invention, the content of the conductive particles is 3 parts by weight or more and 30 parts by weight or less per 100 parts by weight of the curable compound in the conductive paste.

[0013] In a specific aspect of the conductive paste according to the present invention, the conductive particles have a particle size of 10 μm or less.

[0014] In a specific aspect of the conductive paste according to the present invention, the conductive particles include a base particle and a conductive portion disposed on a surface of the base particle, and the conductive portion includes nickel.

[0015] In a specific aspect of the conductive paste according to the present invention, the conductive paste is heated at 150° C. for 10 minutes and the cured product has a storage modulus at 25° C. of 0.7 GPa or more and 3.0 GPa or less.

[0016] In a specific aspect of the conductive paste according to the present invention, the conductive paste is used by being applied to a substrate having a surface tension of 20 mN / m or more and 50 mN / m or less.

[0017] In a specific aspect of the conductive paste according to the present invention, the conductive paste has a planar area of ​​0.50 mm 2 It is used to attach the chips below.

[0018] In a particular aspect of the conductive paste according to the present invention, the conductive paste is used to obtain an RFID inlay.

[0019] According to a broad aspect of the present invention, there is provided an RFID inlay comprising a substrate having wiring on its surface, a chip, and an adhesive bonding the substrate and the chip, the adhesive being made of the conductive paste described above, and the wiring and the chip being electrically connected by the conductive particles in the adhesive.

[0020] According to a broad aspect of the present invention, there is provided a method for manufacturing an RFID inlay, comprising: a first placement step of placing the above-mentioned conductive paste on the surface of a substrate having wiring on its surface; a second placement step of placing a chip on the surface of the conductive paste opposite the substrate; and an adhesion step of forming an adhesive joint using the conductive paste to bond the substrate and the chip by heating and pressurizing the conductive paste, and electrically connecting the wiring and the chip with the conductive particles in the adhesive joint.

[0021] In a particular aspect of the method for manufacturing an RFID inlay according to the present invention, the substrate is elongated, and in the first placement process, the second placement process, and the bonding process, the elongated substrate is transported using a roll-to-roll method to manufacture the RFID inlay.

[0022] According to a broad aspect of the present invention, the conductive paste described above has a planar area of ​​0.50 mm 2 The following uses for bonding chips are provided.

[0023] According to a broad aspect of the present invention, there is provided the use of the conductive paste described above to obtain an RFID inlay. [Effects of the Invention]

[0024] The conductive paste according to the present invention includes a curable compound, a plurality of conductive particles, and a thermal polymerization initiator. In the conductive paste according to the present invention, the curable compound includes a urethane (meth)acrylate having a molecular weight of 1000 or more and an aromatic skeleton, and a polymerizable monomer having a molecular weight of less than 1000 and an aromatic skeleton or an alicyclic skeleton. The viscosity of the conductive paste according to the present invention at 25°C is 5 Pa·s or more and 50 Pa·s or less. The conductive paste according to the present invention, having the above-described configuration, can improve adhesion and electrical conductivity reliability. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below.

[0026] (Conductive paste) The conductive paste according to the present invention comprises (A) a curable compound, a plurality of (B) conductive particles, and (C) a thermal polymerization initiator. In the conductive paste according to the present invention, the curable compound comprises (A1) a urethane (meth)acrylate having a molecular weight of 1000 or more and an aromatic skeleton, and (A2) a polymerizable monomer having a molecular weight of less than 1000 and an aromatic skeleton or an alicyclic skeleton. The viscosity of the conductive paste according to the present invention at 25°C is 5 Pa s or more and 50 Pa s or less.

[0027] The conductive paste according to the present invention has the above-mentioned configuration, and therefore can improve adhesion. Furthermore, the conductive paste according to the present invention has the above-mentioned configuration, and therefore can be positioned on fine wiring with high precision, thereby improving electrical conductivity reliability. Furthermore, the conductive paste according to the present invention has the above-mentioned configuration, and therefore can maintain high electrical conductivity reliability even when a connection structure (electronic component) is left in a high-temperature, high-humidity environment for a long period of time.

[0028] With conventional conductive pastes, it is difficult to improve adhesiveness and conduction reliability, and to maintain high conduction reliability when left in a high-temperature, high-humidity environment for a long period of time.

[0029] The present inventors have found that by combining a specific urethane (meth)acrylate with a specific polymerizable monomer, it is possible to improve the adhesiveness of the conductive paste and also improve the conduction reliability.

[0030] The conductive paste according to the present invention is in a paste state at 25° C. The conductive paste is discharged and used at a temperature of 20° C. to 30° C., for example.

[0031] The viscosity (η25) of the conductive paste at 25°C is preferably 6 Pa·s or more, more preferably 10 Pa·s or more, even more preferably 15 Pa·s or more, and is preferably 48 Pa·s or less, more preferably 45 Pa·s or less, even more preferably 40 Pa·s or less. When the viscosity (η25) is equal to or greater than the lower limit, the conductive paste can be prevented from flowing out of the wiring. When the viscosity (η25) is equal to or less than the upper limit, the conductive paste can be arranged on the fine wiring with even greater precision.

[0032] The viscosity (η25) can be measured, for example, using an E-type viscometer at 25° C. and 5 rpm. Examples of the E-type viscometer include the TV22 Viscometer manufactured by Toki Sangyo Co., Ltd.

[0033] The conductive paste has good adhesive properties and is suitable for use as an adhesive. The conductive paste is particularly suitable for use in bonding a substrate and a chip.

[0034] From the viewpoint of further improving the conduction reliability, the conductive paste is preferably an anisotropic conductive paste. The conductive paste is preferably used for electrically connecting electrodes. The conductive paste is preferably used for obtaining a connection structure. The conductive paste is preferably used for obtaining electronic components. The conductive paste is particularly preferably used for obtaining an RFID inlay (use of the conductive paste for obtaining an RFID inlay). The conductive paste is preferably used for bonding and connecting a chip having electrodes on its surface to a substrate having wiring (antenna pattern) on its surface (use of the conductive paste for bonding and connecting a chip having electrodes on its surface to a substrate having wiring (antenna pattern) on its surface).

[0035] The conductive paste is preferably used by being applied to a substrate having a surface tension of 20 mN / m or more and 50 mN / m or less (use of the conductive paste on a substrate having a surface tension of 20 mN / m or more and 50 mN / m or less). The conductive paste is particularly preferably used by being applied to a substrate having a surface tension of 30 mN / m or more and 50 mN / m or less (use of the conductive paste on a substrate having a surface tension of 30 mN / m or more and 50 mN / m or less). The conductive paste is preferably used by being applied to a substrate having a surface area of ​​0.50 mm 2 It is preferable to use it for bonding chips with a planar area of ​​0.50 mm or less. 2 (Use of the above conductive paste to bond the chip, which is below).

[0036] The conductive paste is preferably thermosetting, and is preferably a thermosetting conductive paste, more preferably a thermosetting anisotropic conductive paste.

[0037] The storage modulus at 25°C of the cured product obtained by heating the conductive paste at 150°C for 10 minutes is preferably 0.7 GPa or more, more preferably 0.8 GPa or more, even more preferably 1.0 GPa or more, particularly preferably 1.5 GPa or more, and is preferably 3.0 GPa or less, more preferably 2.8 GPa or less, and even more preferably 2.5 GPa or less. When the storage modulus at 25°C of the cured product is equal to or greater than the above lower limit and equal to or less than the above upper limit, the adhesiveness can be further improved, and the occurrence of cracks and warping in the adhesive joints of the resulting connection structure can be effectively prevented.

[0038] The storage modulus of the cured product at 25°C can be measured using a dynamic viscoelasticity measuring device (for example, "DVA-200" manufactured by IT Measurement Control Co., Ltd.) Measurement using the dynamic viscoelasticity measuring device can be carried out, for example, using a measurement sample cut out of the cured product to a size of 50 mm in length, 3 mm in width, and 1 mm in thickness under conditions of a frequency of 10 Hz, a strain of 0.1%, and a pulling width and gripping width of 20 mm.

[0039] When the conductive paste according to the present invention is actually used (for example, when a connection structure such as an RFID inlay is produced using the conductive paste), the curing conditions of the conductive paste do not have to be the heating conditions of 150°C and 10 minutes.

[0040] Each component contained in the conductive paste will be described below.

[0041] In this specification, "(meth)acrylate" refers to acrylate and methacrylate, "(meth)acrylic" refers to acrylic and methacrylic, and "(meth)acryloyl" refers to acryloyl and methacryloyl.

[0042] <(A) Curable compound> The conductive paste contains (A) a curable compound. The (A) curable compound contains the following components: (A1) a urethane (meth)acrylate having a molecular weight of 1000 or more and having an aromatic skeleton (hereinafter, this may be referred to as "(A1) urethane (meth)acrylate"); and (A2) a polymerizable monomer having a molecular weight of less than 1000 and having an aromatic skeleton or an alicyclic skeleton (hereinafter, this may be referred to as "(A2) polymerizable monomer").

[0043] In 100% by weight of the conductive paste, the content of the (A) curable compound is preferably 15% by weight or more, more preferably 20% by weight or more, and is preferably 55% by weight or less, more preferably 50% by weight or less, even more preferably 45% by weight or less, particularly preferably 40% by weight or less, and most preferably 35% by weight or less. When the content of the (A) curable compound is equal to or more than the lower limit and equal to or less than the upper limit, adhesion can be further improved and conduction reliability can be further improved.

[0044] The total content of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer in 100% by weight of the conductive paste is preferably 20% by weight or more, more preferably 25% by weight or more. The total content of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer in 100% by weight of the conductive paste is preferably 75% by weight or less, more preferably 70% by weight or less, even more preferably 65% ​​by weight or less, particularly preferably 60% by weight or less, and most preferably 55% by weight or less. When the total content of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer is equal to or greater than the above lower limit and equal to or less than the above upper limit, the viscosity of the conductive paste can be adjusted within a suitable range, and adhesion and conduction reliability can be further improved.

[0045] In 100% by weight of the (A) curable compound, the total content of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer is preferably 20% by weight or more, more preferably 40% by weight or more, and preferably 90% by weight or less, more preferably 80% by weight or less. When the total content of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer is equal to or more than the above lower limit and equal to or less than the above upper limit, the viscosity of the conductive paste can be adjusted within a suitable range, and the adhesiveness and the conduction reliability can be further improved.

[0046] [(A1) Urethane (meth)acrylate] The (A1) urethane (meth)acrylate has a molecular weight of 1000 or more and has an aromatic skeleton. The (A1) urethane (meth)acrylate is an aromatic urethane (meth)acrylate having a molecular weight of 1000 or more.

[0047] The (A1) urethane (meth)acrylate has an aromatic skeleton, a urethane bond, and a (meth)acryloyl group. The (A1) urethane (meth)acrylate may be a urethane (meth)acrylate having one (meth)acryloyl group, or may be a urethane (meth)acrylate having two or more (meth)acryloyl groups. The (A1) urethane (meth)acrylate may be a monofunctional (meth)acrylate, a bifunctional (meth)acrylate, a trifunctional (meth)acrylate, or a tetrafunctional or higher (meth)acrylate. The (A1) urethane (meth)acrylate may have 100 or less (meth)acryloyl groups, 50 or less, or 10 or less.

[0048] Examples of the (A1) urethane (meth)acrylate include "CN973", "CN978NS", "CN992", "CN9167", "CN9782", "CN9783", "CN970", "CN971", "CN972", "CN975NS", and "CN9165" (all manufactured by Sartomer Chemical Industry Co., Ltd.), "UN-9200A", "UN-9000PEP", "UN-5500", and "UN-5590" (all manufactured by Negami Chemical Industrial Co., Ltd.), "EBECRYL210" and "EBECRYL220" (all manufactured by Daicel Allnex Corporation), "GENOMER4217" (manufactured by Rahn AG), and "SU704", "SU710", "SU720", "SU7206", "PSU537M2", and "PSU537M10" (all manufactured by Okajima Corporation).

[0049] The (A1) urethane (meth)acrylate can be obtained, for example, by the following methods: A method of reacting a polyol compound, an isocyanate compound, and a (meth)acrylic acid derivative having an aromatic skeleton in the presence of a catalyst; A method of reacting a polyol compound having an aromatic skeleton, an isocyanate compound, and a (meth)acrylic acid derivative in the presence of a catalyst; A method of reacting a polyol compound having an aromatic skeleton with a (meth)acrylic acid derivative having an isocyanate group in the presence of a catalyst; A method of reacting an isocyanate compound having an aromatic skeleton with a (meth)acrylic acid derivative having a hydroxyl group in the presence of a catalyst.

[0050] The molecular weight of the (A1) urethane (meth)acrylate is preferably 1500 or more, more preferably 2000 or more, even more preferably 3000 or more, and particularly preferably 5000 or more, and is preferably 30000 or less, more preferably 25000 or less, even more preferably 20000 or less, and particularly preferably 18000 or less. When the molecular weight of the (A1) urethane (meth)acrylate is not less than the above lower limit and not more than the above upper limit, the adhesiveness can be further improved and the conduction reliability can be further improved.

[0051] The molecular weight of the (A1) urethane (meth)acrylate refers to a molecular weight that can be calculated from the structural formula when the structural formula of the (A1) urethane (meth)acrylate can be identified. Furthermore, when the (A1) urethane (meth)acrylate is a polymer or the like whose structural formula cannot be identified, the molecular weight refers to a weight-average molecular weight. The weight-average molecular weight refers to a weight-average molecular weight measured by gel permeation chromatography (GPC) in terms of polystyrene. The molecular weight of the (A1) urethane (meth)acrylate is preferably a weight-average molecular weight measured by gel permeation chromatography (GPC) in terms of polystyrene. The weight-average molecular weight can be measured using the following measuring device and under the following measuring conditions.

[0052] Measurement equipment: Waters GPC System (Waters 2690 + Waters 2414 (RI)) manufactured by Japan Waters Measurement conditions Column: Shodex GPC LF-G x 1, Shodex GPC LF-804 x 2 Mobile phase: THF 1.0mL / min Sample concentration: 5mg / mL Detector: Refractive index detector (RID) Standard material: Polystyrene (TOSOH Corporation, weight average molecular weight: 620-590,000)

[0053] The viscosity of the (A1) urethane (meth)acrylate at 25°C is preferably 10 Pa·s or more, more preferably 50 Pa·s or more, even more preferably 100 Pa·s or more, and is preferably 3000 Pa·s or less, more preferably 2500 Pa·s or less, and even more preferably 2000 Pa·s or less. When the (A1) urethane (meth)acrylate has a viscosity at 25°C that is equal to or greater than the above lower limit and equal to or less than the above upper limit, the adhesiveness can be further improved and the conductivity reliability can be further improved.

[0054] The viscosity of the (A1) urethane (meth)acrylate at 25°C can be measured, for example, using an E-type viscometer at 25°C and 5 rpm. Examples of the E-type viscometer include the TV22 Viscometer manufactured by Toki Sangyo Co., Ltd.

[0055] The content of the urethane (meth)acrylate (A1) in 100% by weight of the conductive paste is preferably 15% by weight or more, more preferably 20% by weight or more, and preferably 55% by weight or less, more preferably 50% by weight or less. When the total content of the urethane (meth)acrylate (A1) is equal to or more than the above lower limit and equal to or less than the above upper limit, the adhesiveness can be further improved and the conduction reliability can be further improved.

[0056] The content of the urethane (meth)acrylate (A1) in 100% by weight of the curable compound (A) is preferably 15% by weight or more, more preferably 20% by weight or more, and preferably 50% by weight or less, more preferably 45% by weight or less. When the total content of the urethane (meth)acrylate (A1) is equal to or more than the lower limit and equal to or less than the upper limit, adhesion can be further improved and conduction reliability can be further improved.

[0057] The content of the urethane (meth)acrylate (A1) is preferably 15% by weight or more, more preferably 20% by weight or more, and preferably 70% by weight or less, more preferably 65% ​​by weight or less, based on a total of 100% by weight of the urethane (meth)acrylate (A1) and the polymerizable monomer (A2). When the content of the urethane (meth)acrylate (A1) is equal to or more than the lower limit and equal to or less than the upper limit, the viscosity of the conductive paste can be adjusted within a suitable range, and the adhesiveness and the conduction reliability can be further improved.

[0058] [(A2) Polymerizable monomer] The (A2) polymerizable monomer has a molecular weight of less than 1,000 and has an aromatic skeleton or an alicyclic skeleton. The (A2) polymerizable monomer may have an aromatic skeleton, an alicyclic skeleton, or both an aromatic skeleton and an alicyclic skeleton. The (A2) polymerizable monomer may contain a polymerizable monomer having an aromatic skeleton and a polymerizable monomer having an alicyclic skeleton. The (A2) polymerizable monomer is preferably a polymerizable monomer other than a urethane (meth)acrylate having an aromatic skeleton, and more preferably a polymerizable monomer other than a urethane (meth)acrylate. The (A2) polymerizable monomer is a polymerizable component that can be homopolymerized or copolymerized.

[0059] Examples of the polymerizable monomer having an aromatic skeleton include 2-phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, ethoxylated (4) nonylphenol (meth)acrylate, alkoxylated phenol (meth)acrylate, ethoxylated (3) bisphenol A (meth)diacrylate, ethoxylated (4) bisphenol A (meth)diacrylate, ethoxylated (10) bisphenol A (meth)diacrylate, and ethoxylated (30) bisphenol A (meth)diacrylate. From the viewpoint of improving compatibility with the urethane (meth)acrylate (A1), the polymerizable monomer having an aromatic skeleton (A2) is preferably 2-phenoxyethyl (meth)acrylate or ethoxylated (3) bisphenol A (meth)diacrylate.

[0060] Examples of the polymerizable monomer having an alicyclic skeleton include cyclohexyl (meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, isobornyl (meth)acrylate, 4-tert-butylcyclohexanol, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, acrylomorpholine, and 3,3,5-trimethylcyclohexyl (meth)acrylate. From the viewpoint of improving compatibility with the urethane (meth)acrylate (A1), the polymerizable monomer (A2) having an alicyclic skeleton is preferably cyclohexyl (meth)acrylate or isobornyl (meth)acrylate.

[0061] The molecular weight of the (A2) polymerizable monomer is preferably 50 or more, more preferably 100 or more, even more preferably 150 or more, and particularly preferably 200 or more, and is preferably 950 or less, more preferably 900 or less, even more preferably 800 or less, and particularly preferably 700 or less. When the molecular weight of the (A2) polymerizable monomer is equal to or more than the above lower limit and equal to or less than the above upper limit, compatibility with the (A1) urethane (meth)acrylate is improved, the viscosity of the conductive paste can be adjusted within a suitable range, and the adhesiveness and conduction reliability can be further improved.

[0062] The molecular weight of the (A2) polymerizable monomer means a molecular weight that can be calculated from the structural formula when the structural formula of the (A2) polymerizable monomer can be identified. Furthermore, when the (A2) polymerizable monomer is a polymer or the like whose structural formula cannot be identified, the molecular weight means a weight average molecular weight. The weight average molecular weight is a weight average molecular weight measured by gel permeation chromatography (GPC) in terms of polystyrene. Since the (A2) polymerizable monomer has a relatively small molecular weight, its structural formula can generally be identified. The weight average molecular weight can be measured using the following measuring device and under the following measuring conditions.

[0063] Measurement equipment: Waters GPC System (Waters 2690 + Waters 2414 (RI)) manufactured by Japan Waters Measurement conditions Column: Shodex GPC LF-G x 1, Shodex GPC LF-804 x 2 Mobile phase: THF 1.0mL / min Sample concentration: 5mg / mL Detector: Refractive index detector (RID) Standard material: Polystyrene (TOSOH Corporation, weight average molecular weight: 620-590,000)

[0064] The viscosity of the polymerizable monomer (A2) at 25°C is preferably 5 Pa·s or more, more preferably 10 Pa·s or more, even more preferably 15 Pa·s or more, and is preferably 50 Pa·s or less, more preferably 45 Pa·s or less, even more preferably 40 Pa·s or less. When the viscosity of the polymerizable monomer (A2) at 25°C is equal to or more than the above lower limit and equal to or less than the above upper limit, the conductive paste can be arranged on fine wiring with even greater precision and the wettability to the substrate can be improved.

[0065] The viscosity of the polymerizable monomer (A2) at 25°C can be measured, for example, using an E-type viscometer at 25°C and 5 rpm. Examples of the E-type viscometer include the TV22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0066] The content of the (A2) polymerizable monomer in 100% by weight of the conductive paste is preferably 10% by weight or more, more preferably 15% by weight or more, and preferably 50% by weight or less, more preferably 45% by weight or less. When the content of the (A2) polymerizable monomer is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, compatibility with the (A1) urethane (meth)acrylate is improved, the viscosity of the conductive paste can be adjusted within a suitable range, and adhesion and conductivity reliability can be further improved. Note that when the (A2) polymerizable monomer contains a polymerizable monomer having an aromatic skeleton and a polymerizable monomer having an alicyclic skeleton, the content of the (A2) polymerizable monomer refers to the total content of the polymerizable monomer having an aromatic skeleton and the polymerizable monomer having an alicyclic skeleton.

[0067] The content of the (A2) polymerizable monomer in 100% by weight of the (A) curable compound is preferably 10% by weight or more, more preferably 15% by weight or more, and preferably 55% by weight or less, more preferably 50% by weight or less. When the content of the (A2) polymerizable monomer is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, compatibility with the (A1) urethane (meth)acrylate is improved, the viscosity of the conductive paste can be adjusted within a suitable range, and adhesion and conductivity reliability can be further improved. Note that when the (A2) polymerizable monomer contains a polymerizable monomer having an aromatic skeleton and a polymerizable monomer having an alicyclic skeleton, the content of the (A2) polymerizable monomer refers to the total content of the polymerizable monomer having an aromatic skeleton and the polymerizable monomer having an alicyclic skeleton.

[0068] The content of the (A2) polymerizable monomer is preferably 15 wt% or more, more preferably 20 wt% or more, and preferably 55 wt% or less, more preferably 50 wt% or less, based on a total of 100 wt% of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer. When the content of the (A2) polymerizable monomer is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, compatibility with the (A1) urethane (meth)acrylate is improved, the viscosity of the conductive paste can be adjusted within a suitable range, and adhesion and conductivity reliability can be further improved. When the (A2) polymerizable monomer contains a polymerizable monomer having an aromatic skeleton and a polymerizable monomer having an alicyclic skeleton, the content of the (A2) polymerizable monomer refers to the total content of the polymerizable monomer having an aromatic skeleton and the polymerizable monomer having an alicyclic skeleton.

[0069] The (A) curable compound may contain a curable compound other than both the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer. The (A) curable compound may contain a urethane (meth)acrylate other than both the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer. The (A) curable compound may contain a polymerizable component (polymerizable monomer) other than both the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer. The curable compound (polymerizable component) other than the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer is not particularly limited. The curable compound (polymerizable component) other than the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer may be a monofunctional (meth)acrylate or a polyfunctional (meth)acrylate. The curable compound (polymerizable component) other than the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer may be a bifunctional (meth)acrylate, a trifunctional (meth)acrylate, or a tetrafunctional or higher (meth)acrylate. The curable compound (polymerizable component) other than the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer may have 100 or less, 50 or less, or 10 or less (meth)acryloyl groups.

[0070] Examples of the monofunctional (meth)acrylate include 2-(2-ethoxyethoxy)ethyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, lauryl (meth)acrylate, isobutyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, octyl / decyl (meth)acrylate, tridecyl (meth)acrylate, nonyl (meth)acrylate, caprolactone (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, (2-methyl-2-ethyl-1,3 dioxolan-4-yl)methyl (meth)acrylate, (3-ethyloxetane Examples of the acrylic acid esters include (methyl-3-yl)methyl (meth)acrylate, methoxyethyl (meth)acrylate, methoxypolyethylene glycol (350) mono(meth)acrylate, methoxytriethylene glycol (meth)acrylate, alkoxylated tetrahydrofurfuryl (meth)acrylate, alkoxylated lauryl (meth)acrylate, dimethylacrylamide, diethylacrylamide, hydroxyethylacrylamide, dimethylaminopropylacrylamide, isopropylacrylamide, N-acryloyloxyethylhexahydrophthalimide, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0071] Examples of the polyfunctional (meth)acrylate include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol (meth)acrylate, 1,9-nonanediol di(meth)acrylate, polyethylene glycol (200) di(meth)acrylate, tetraethylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol (400) di(meth)acrylate, dipropylene glycol di(meth)acrylate, alkoxylated hexanediol di(meth)acrylate, dodecanediol di(meth)acrylate, acrylate, polyethylene glycol (600) di(meth)acrylate, polypropylene glycol (700) (meth)acrylate, propoxylated (2) neopentyl glycol di(meth)acrylate, alkoxylated neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tris-(2-hydroxyethyl) isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated (3) trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. From the viewpoint of increasing the storage modulus of the cured product and further enhancing adhesiveness, the (A) curable compound preferably contains a curable compound (polymerizable component) other than the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer. From the viewpoint of increasing the storage modulus of the cured product and further enhancing adhesiveness, the (A1) curable compound (polymerizable component) other than the (A2) urethane (meth)acrylate and the (A2) polymerizable monomer preferably contains a polyfunctional curable compound, more preferably a polyfunctional (meth)acrylate.

[0072] <(B) Conductive particles> The conductive paste includes a plurality of (B) conductive particles. The (B) conductive particles are not particularly limited. The (B) conductive particles may be solder particles or metal particles. The (B) conductive particles may include a base particle and a conductive portion disposed on the surface of the base particle. From the viewpoint of further improving the conduction reliability, the (B) conductive particles preferably include a base particle and a conductive portion disposed on the surface of the base particle.

[0073] The particle diameter of the (B) conductive particles is preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 3 μm or more, and is preferably 100 μm or less, more preferably 30 μm or less, and even more preferably 10 μm or less. When the particle diameter of the (B) conductive particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the conduction reliability can be further improved.

[0074] The particle size of the (B) conductive particles is preferably an average particle size, more preferably a number average particle size, which can be determined, for example, by observing 50 random conductive particles with an electron microscope or an optical microscope and calculating the average particle size of each conductive particle, or by performing laser diffraction particle size distribution measurement.

[0075] When measuring the particle diameter of the (B) conductive particles by observing 50 random conductive particles using an electron microscope or optical microscope, the measurement can be performed, for example, as follows. The conductive particles are added to Kulzer's Technovit 4000 so that the content is 30 wt % and dispersed to prepare a resin embedding body for conductive particle inspection. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) is used to cut out a cross section of the conductive particles so that it passes through the center of the conductive particles dispersed in the resin embedding body for inspection. Then, using a field emission scanning electron microscope (FE-SEM) with an image magnification set to 25,000x, 50 conductive particles are randomly selected and observed. The equivalent circle diameter of each conductive particle is measured, and the arithmetic average is calculated to determine the particle diameter of the conductive particles.

[0076] The coefficient of variation (CV value) of the particle diameter of the (B) conductive particles is preferably 10% or less, more preferably 5% or less. When the coefficient of variation of the particle diameter of the (B) conductive particles is equal to or less than the upper limit, the electrical conductivity reliability can be further improved. There is no particular limitation on the lower limit of the coefficient of variation (CV value) of the particle diameter of the (B) conductive particles. The coefficient of variation (CV value) of the particle diameter of the (B) conductive particles may be 0% or more, or may be 1% or more.

[0077] The coefficient of variation (CV value) can be measured as follows.

[0078] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of the particle size of the conductive particles Dn: average particle diameter of conductive particles

[0079] The shape of the (B) conductive particles is not particularly limited, and the (B) conductive particles may be spherical, may have a shape other than spherical, or may be flat or the like.

[0080] In 100% by weight of the conductive paste, the content of the (B) conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and is preferably 80% by weight or less, more preferably 60% by weight or less, even more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the (B) conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the conduction reliability can be further improved.

[0081] The content of the (B) conductive particles relative to 100 parts by weight of the (A) curable compound in the conductive paste is preferably 2 parts by weight or more, more preferably 3 parts by weight or more, even more preferably 5 parts by weight or more, and particularly preferably 7 parts by weight or more. The content of the (B) conductive particles relative to 100 parts by weight of the (A) curable compound in the conductive paste is preferably 35 parts by weight or less, more preferably 30 parts by weight or less, even more preferably 25 parts by weight or less, and particularly preferably 20 parts by weight or less. When the content of the (B) conductive particles in the conductive paste is equal to or greater than the above lower limit and equal to or less than the above upper limit, the conductivity reliability can be further improved.

[0082] The content of the (B) conductive particles is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, and even more preferably 7 parts by weight or more, relative to 100 parts by weight of the total of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer in the conductive paste. The content of the (B) conductive particles is preferably 30 parts by weight or less, more preferably 25 parts by weight or less, and even more preferably 20 parts by weight or less, relative to 100 parts by weight of the total of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer in the conductive paste. When the content of the (B) conductive particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the conductivity reliability can be further improved.

[0083] When the (B) conductive particles are metal particles, examples of the metal particles include silver, copper, nickel, silicon, gold, titanium, and alloys such as solder. From the viewpoint of more effectively improving the electrical conductivity reliability, the material of the metal particles preferably contains nickel or a nickel alloy, and more preferably the material of the metal particles is nickel or a nickel alloy. From the viewpoint of more effectively improving the electrical conductivity reliability, the outer surface portions of the metal particles preferably contain nickel or a nickel alloy.

[0084] Hereinafter, the conductive particle including a base particle and a conductive portion disposed on the surface of the base particle will be described in detail.

[0085] (base material particles) Examples of the base particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particles may be core-shell particles having a core and a shell disposed on the surface of the core. The core may be an organic core, and the shell may be an inorganic shell.

[0086] The base particles are more preferably resin particles or organic-inorganic hybrid particles, and may be either resin particles or organic-inorganic hybrid particles. By using these preferred base particles, the effects of the present invention are more effectively exhibited.

[0087] Various resins are suitable for use as the material for the resin particles. Examples of materials for the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyalkylene terephthalate, polycarbonate, polyamide, phenol-formaldehyde resin, melamine-formaldehyde resin, benzoguanamine-formaldehyde resin, urea-formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamide-imide, polyether ether ketone, polyether sulfone, divinylbenzene polymer, and polymers obtained by polymerizing one or more of various polymerizable monomers having an ethylenically unsaturated group. The divinylbenzene polymer may be a divinylbenzene copolymer. Examples of the divinylbenzene copolymer include a divinylbenzene-styrene copolymer and a divinylbenzene-(meth)acrylic acid ester copolymer.

[0088] Since it is possible to design and synthesize resin particles having any compression characteristics suitable for a conductive paste, and the hardness of the resin particles can be easily controlled within a suitable range, it is preferable that the material of the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having multiple ethylenically unsaturated groups.

[0089] When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer.

[0090] Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; alkyl (meth)acrylate compounds such as 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, and isobornyl (meth)acrylate; and 2-hydroxyethyl Examples of the monomer include oxygen atom-containing (meth)acrylate compounds such as (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate; nitrile-containing monomers such as (meth)acrylonitrile; acid vinyl ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; and halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

[0091] Examples of the crosslinkable monomer include 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)propane ... Examples of suitable (meth)acrylates include polyfunctional (meth)acrylate compounds such as pyrene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; and silane-containing monomers such as triallyl (iso)cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

[0092] The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method, such as a suspension polymerization method in the presence of a radical polymerization initiator, or a method in which non-crosslinked seed particles are used to swell and polymerize the monomer together with the radical polymerization initiator.

[0093] When the base particles are inorganic particles other than metal particles or organic-inorganic hybrid particles, examples of the inorganic material of the base particles include silica, alumina, barium titanate, zirconia, and carbon black. It is preferable that the inorganic material is not metal. The particles formed from silica are not particularly limited, but examples include particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, followed by calcination as necessary. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

[0094] The organic-inorganic hybrid particles are preferably core-shell 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 more effectively reducing the connection resistance between electrodes, the base particle is preferably an organic-inorganic hybrid particle having an organic core and an inorganic shell disposed on the surface of the organic core.

[0095] Examples of the material for the organic core include the materials for the resin particles described above.

[0096] Examples of materials for the inorganic shell include the inorganic substances listed as materials for the base particle described above. The material for the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a shell-like substance from a metal alkoxide on the surface of the core by a sol-gel method and then firing the shell-like substance. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed from a silane alkoxide.

[0097] When the base particles are metal particles, examples of the metal that is the material of the metal particles include silver, copper, nickel, silicon, gold, titanium, and alloys such as solder.

[0098] The particle diameter of the base particle is preferably 0.05 μm or more, more preferably 0.01 μm or more, even more preferably 0.5 μm or more, even more preferably 1 μm or more, particularly preferably 3 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, particularly preferably 10 μm or less. When the particle diameter of the base particle is equal to or greater than the lower limit, the electrical conductivity reliability is further improved. Furthermore, when forming a conductive portion on the surface of the base particle, aggregation is less likely to occur, and aggregated conductive particles are less likely to be formed. When the particle diameter of the base particle is equal to or less than the upper limit, the conductive particles are easily compressed sufficiently, and the connection resistance between electrodes connected via the conductive particles can be further effectively reduced.

[0099] The particle diameter of the base particles is preferably an average particle diameter, and more preferably a number-average particle diameter. The number-average particle diameter of the base particles can be measured, for example, as follows. The conductive particles are added to Kulzer's Technovit 4000 so that the content is 30% by weight, and dispersed to prepare a conductive particle embedding resin for inspection. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) is used to cut out a cross section of the conductive particles dispersed in the embedding resin for inspection, passing through the vicinity of the center of the base particle. Then, using a field emission scanning electron microscope (FE-SEM) with an image magnification set to 25,000x, 50 conductive particles are randomly selected, and the base particle of each conductive particle is observed. The particle diameter of the base particle in each conductive particle is measured, and the arithmetic average is used to determine the average particle diameter of the base particle.

[0100] (Conductive part) The conductive portion preferably contains a metal. The metal constituting the conductive portion is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, ruthenium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, as well as alloys thereof. Tin-doped indium oxide (ITO) may also be used as the metal. Only one of the metals may be used, or two or more may be used in combination. From the viewpoint of further reducing the connection resistance between electrodes, tin-containing alloys, nickel, palladium, ruthenium, silver, copper, or gold are preferred, and nickel or palladium is more preferred.

[0101] From the viewpoint of more effectively improving the conduction reliability, it is preferable that the conductive portion contains nickel, and it is more preferable that the outer surface portion of the conductive portion contains nickel.

[0102] The nickel content in 100% by weight of the nickel-containing conductive portion is preferably 10% by weight or more, more preferably 50% by weight or more, even more preferably 60% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more. The nickel content in 100% by weight of the nickel-containing conductive portion may be 99% by weight or less, 90% by weight or less, or 70% by weight or less.

[0103] The conductive portion may be formed of one layer. The conductive portion may be formed of multiple layers. That is, the conductive portion may have a laminated structure of two or more layers. When the conductive portion is formed of multiple layers, the metal constituting the outermost layer is preferably an alloy containing gold, silver, nickel, palladium, ruthenium, copper, or tin, and more preferably nickel. When the metal constituting the outermost layer is one of these preferred metals, the connection resistance between the electrodes is further reduced.

[0104] The method for forming the conductive portion on the surface of the base particle is not particularly limited. Examples of methods for forming the conductive portion include electroless plating, electroplating, physical collision, mechanochemical reaction, physical vapor deposition or physical adsorption, and coating the surface of the base particle with a metal powder or a paste containing a metal powder and a binder. The method for forming the conductive portion is preferably electroless plating, electroplating, or physical collision. Examples of physical vapor deposition methods include vacuum deposition, ion plating, and ion sputtering. Furthermore, the physical collision method uses, for example, a sheeter composer (manufactured by Tokuju Manufacturing Co., Ltd.).

[0105] The thickness of the conductive portion 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 even more preferably 0.3 μm or less. When the thickness of the conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, allowing the conductive particles to be sufficiently deformed during connection.

[0106] When the conductive portion is formed of multiple layers, the thickness of the conductive portion of the outermost layer 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 conductive portion of the outermost layer is equal to or greater than the above lower limit and equal to or less than the above upper limit, the conductive portion of the outermost layer becomes uniform, the corrosion resistance is sufficiently high, and the connection resistance between electrodes can be sufficiently low.

[0107] The thickness of the conductive portion can be measured by observing the cross section of the conductive particle using, for example, a transmission electron microscope (TEM).

[0108] Core material: The (B) conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. An oxide film is often formed on the surface of the electrodes connected by the (B) conductive particles. When using (B) conductive particles with protrusions on the surface of the conductive portion, the oxide film can be effectively removed by placing the (B) conductive particles between the electrodes and pressing them together. This ensures more reliable contact between the electrodes and the conductive portion, further reducing the connection resistance between the electrodes. Furthermore, when connecting the electrodes, the protrusions of the (B) conductive particles can effectively remove the filler between the (B) conductive particles and the electrodes. This further increases the reliability of electrical connection between the electrodes.

[0109] Methods for forming the protrusions include a method of adhering a core material to the surface of a base particle and then forming a conductive portion by electroless plating, and a method of forming a conductive portion on the surface of a base particle by electroless plating, then adhering a core material, and then further forming a conductive portion by electroless plating, etc. Alternatively, to form the protrusions, a method may be used in which, without using the core material, a conductive portion is formed on the base particle by electroless plating, and then a protruding plating is deposited on the surface of the conductive portion, and then a conductive portion is formed by electroless plating, etc.

[0110] Examples of methods for adhering a core substance to the surface of a base particle include a method of adding a core substance to a dispersion of base particles and accumulating and adhering the core substance to the surface of the base particle by van der Waals forces, and a method of adding a core substance to a container containing base particles and adhering the core substance to the surface of the base particle by mechanical action such as rotating the container.From the viewpoint of controlling the amount of core substance to be adhered, the method for adhering a core substance to the surface of a base particle is preferably a method of adhering the core substance to the surface of the base particle by accumulating and adhering the core substance to the surface of the base particle in a dispersion.

[0111] The materials constituting the core material include conductive materials and non-conductive materials. Examples of the conductive materials include conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. Examples of the conductive polymers include polyacetylene. Examples of the non-conductive materials include silica, alumina, titanium oxide, tungsten carbide, and zirconia. From the viewpoint of further improving the reliability of conduction between electrodes, it is preferable that the core material be a metal.

[0112] The metal is not particularly limited. Examples of the metal include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, as well as alloys composed of two or more metals, such as tin-lead alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide. From the viewpoint of further improving the reliability of conduction between electrodes, the metal is preferably nickel, copper, silver, or gold. The metal may be the same as or different from the metal constituting the conductive portion.

[0113] The shape of the core material is not particularly limited. The core material is preferably in the form of a mass. Examples of the core material include particulate masses, aggregates formed by aggregating multiple microparticles, and amorphous masses.

[0114] The particle size (average particle size) of the core material is preferably 0.001 μm or more, more preferably 0.05 μm or more, and preferably 0.9 μm or less, more preferably 0.2 μm or less. When the particle size of the core material is equal to or more than the above lower limit and equal to or less than the above upper limit, the connection resistance between electrodes can be effectively reduced.

[0115] The particle size of the core substance is preferably an average particle size, more preferably a number average particle size, which can be determined, for example, by observing 50 random core substances with an electron microscope or an optical microscope and calculating the average particle size of each core substance, or by performing laser diffraction particle size distribution measurement.

[0116] <(C) Thermal polymerization initiator> The conductive paste contains a thermal polymerization initiator (C). The thermal polymerization initiator (C) is a compound that can initiate polymerization by heating.

[0117] The conductive paste contains the thermal polymerization initiator (C), so that the polymerizable components in the conductive paste can be polymerized by heating. The conductive paste contains the thermal polymerization initiator (C), so that the polymerization of the urethane (meth)acrylate (A1) and the polymerizable monomer (A2) is initiated by heating.

[0118] In the conductive paste, heating may cause copolymerization of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer, or each of them may homopolymerize. In the conductive paste, heating may cause the formation of a homopolymer of the (A1) urethane (meth)acrylate, a homopolymer of the (A2) polymerizable monomer, or a copolymer of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer. From the viewpoint of further improving adhesion and further improving conduction reliability, it is preferable that heating cause the formation of a copolymer of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer.

[0119] The thermal polymerization initiator (C) preferably contains a thermal radical polymerization initiator, and is preferably a thermal radical polymerization initiator. Examples of the thermal radical polymerization initiator include peroxide radical polymerization initiators, azo radical polymerization initiators, and redox radical polymerization initiators. The thermal polymerization initiator (C) may be used alone or in combination of two or more.

[0120] Examples of the azo radical polymerization initiator include azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and azobisdimethylvaleronitrile.

[0121] Examples of the peroxide radical polymerization initiator include diacyl radical polymerization initiators, peroxyester radical polymerization initiators, dialkyl radical polymerization initiators, percarbonate radical polymerization initiators, and ketone peroxide radical polymerization initiators. Examples of the diacyl radical polymerization initiator include lauroyl peroxide and benzoyl peroxide. Examples of the peroxyester radical polymerization initiator include t-butyl peroxybenzoate, t-butyl peroxyacetate, t-butyl peroxypivalate, and t-butyl peroxy-2-ethylhexanoate. Examples of the dialkyl radical polymerization initiator include dicumyl peroxide and di-t-butyl peroxide. Examples of the percarbonate radical polymerization initiator include diisopropyl peroxydicarbonate. Examples of the ketone peroxide radical polymerization initiator include methyl ethyl ketone peroxide.

[0122] The redox radical polymerization initiator contains, for example, a peroxide and a reducing agent or a metal-containing compound. Specific examples of the redox radical polymerization initiator include a mixture of benzoyl peroxide and an organic amine, a mixture of the peroxyester radical polymerization initiator and a reducing agent such as a mercaptan, and a mixture of methyl ethyl ketone peroxide and an organic cobalt salt.

[0123] From the viewpoint of enhancing reactivity and storage stability, the (C) thermal polymerization initiator preferably contains a peroxide-based radical polymerization initiator.

[0124] From the viewpoint of enhancing reactivity and storage stability, the content of the (C) thermal polymerization initiator in 100% by weight of the conductive paste is preferably 0.1% by weight or more, more preferably 0.3% by weight or more, even more preferably 0.5% by weight or more, and is preferably 5% by weight or less, more preferably 4% by weight or less, even more preferably 3% by weight or less.

[0125] The content of the (C) thermal polymerization initiator relative to 100 parts by weight of the (A) curable compound in the conductive paste is preferably 0.3 parts by weight or more, more preferably 0.5 parts by weight or more, even more preferably 0.7 parts by weight or more, and is preferably 6 parts by weight or less, more preferably 5 parts by weight or less, and even more preferably 4 parts by weight or less. When the content of the (C) thermal polymerization initiator is not less than the above lower limit and not more than the above upper limit, reactivity and storage stability can be improved.

[0126] The content of the (C) thermal polymerization initiator relative to 100 parts by weight of the total of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer in the conductive paste is preferably 0.4 parts by weight or more, more preferably 0.6 parts by weight or more, and even more preferably 0.8 parts by weight or more. The content of the (C) thermal polymerization initiator relative to 100 parts by weight of the total of the (A1) urethane (meth)acrylate and the (A2) polymerizable monomer in the conductive paste is preferably 8 parts by weight or less, more preferably 7 parts by weight or less, and even more preferably 6 parts by weight or less. When the content of the (C) thermal polymerization initiator is equal to or more than the above lower limit and equal to or less than the above upper limit, reactivity and storage stability can be improved.

[0127] <Other ingredients> The conductive paste may contain components other than the (A) curable compound, the (B) conductive particles, and the (C) thermal polymerization initiator, such as a solvent, a photopolymerization initiator, an inorganic filler, an organic filler, a colorant, a polymerization inhibitor, a chain transfer agent, an antioxidant, an ultraviolet absorber, an antifoaming agent, a leveling agent, a surfactant, a slip agent, an antiblocking agent, a wax, a masking agent, a deodorizer, a fragrance, a preservative, an antibacterial agent, an antistatic agent, and an adhesion promoter.

[0128] (Use of conductive paste) The use of the present invention is a method for manufacturing a conductive paste having a surface area of ​​0.50 mm 2The use of the present invention for bonding a chip is as follows: In the use according to the present invention, a specific conductive paste and a chip with a specific planar area are used, which can improve adhesion (between the substrate and the chip) and improve the electrical connection reliability.

[0129] From the viewpoint of further increasing the adhesiveness (between the substrate and the chip) and further increasing the reliability of electrical conduction, the plane area of ​​the chip is preferably 0.04 mm 2 More than 0.09mm, preferably 0.09mm 2 More preferably, 0.16 mm 2 or more, preferably 0.50 mm 2 Less than or equal to 0.40 mm, preferably 2 Less than 0.30 mm, more preferably 2 The following is the result.

[0130] The use according to the present invention is also directed to the use of the conductive paste described above to obtain an RFID inlay. In the use according to the present invention, a specific conductive paste is used, which can improve adhesion (between the substrate and the chip) and enhance the reliability of electrical conduction.

[0131] (RFID inlay and manufacturing method of RFID inlay) The RFID inlay of the present invention comprises a substrate having wiring on its surface, a chip, and an adhesive portion bonding the substrate and the chip. In the RFID inlay of the present invention, the material of the adhesive portion is the conductive paste described above. In the RFID inlay of the present invention, the wiring and the chip are electrically connected by the conductive particles in the adhesive portion.

[0132] The method for manufacturing an RFID inlay according to the present invention comprises the following steps (1) to (3): (1) a first placement step of placing the above-mentioned conductive paste on a surface of a substrate having wiring on its surface; (2) a second placement step of placing a chip on the surface of the conductive paste opposite the substrate side; and (3) a bonding step of forming an adhesive joint that bonds the substrate and the chip with the conductive paste by heating and pressurizing the conductive paste, and electrically connecting the wiring and the chip with the conductive particles in the adhesive joint.

[0133] The RFID inlay and the manufacturing method of the RFID inlay according to the present invention use a specific conductive paste, which can improve the adhesion between the substrate and the chip and also improve the reliability of the electrical connection.

[0134] In the method for manufacturing an RFID inlay, it is preferable that the substrate is long, and that the RFID inlay is manufactured by conveying the long substrate by a roll-to-roll method in the first arrangement step, the second arrangement step, and the bonding step. In this case, multiple RFID inlays can be manufactured continuously, further improving the manufacturing efficiency of RFID inlays.

[0135] When the roll-to-roll method is used, the transport speed of the substrate is not particularly limited.

[0136] Examples of methods for disposing the conductive paste include application using a dispenser, screen printing, and ejection using an inkjet device.

[0137] The heating temperature in the bonding step is preferably 100° C. or higher, more preferably 150° C. or higher, and preferably 400° C. or lower, more preferably 300° C. or lower, and even more preferably 250° C. or lower. When the heating temperature in the bonding step is equal to or higher than the lower limit and equal to or lower than the upper limit, good electrical connection between the chip and the antenna can be achieved.

[0138] The applied pressure in the bonding step is preferably 0.5 N or more, more preferably 1 N or more, and is preferably 3.5 N or less, more preferably 3 N or less, and even more preferably 2.5 N or less. When the applied pressure in the bonding step is equal to or greater than the lower limit and equal to or less than the upper limit, good electrical connection between the chip and the antenna can be achieved.

[0139] The heating and pressurizing time in the bonding step is not particularly limited and may be 5 seconds or more, 15 seconds or less, or 10 seconds or less.

[0140] The RFID inlay may be cut to a predetermined size as needed, or may be used after being cut. Preferably, a plurality of the chips are adhered to a long substrate by a plurality of the adhesive parts. A plurality of stacks of the chips and the adhesive parts may be arranged on the long substrate. In the first arranging step, it is preferable to arrange the conductive paste at a plurality of locations on the surface of the long substrate. In the second arranging step, it is preferable to use a plurality of chips and arrange the chips on the surface opposite the substrate side of each of the conductive pastes arranged at a plurality of locations. After the chips are adhered to the long substrate by the adhesive parts, the long substrate may be cut.

[0141] The substrate is not particularly limited. The substrate is preferably a circuit board. Examples of the circuit board include a resin film, a flexible printed circuit board, a rigid-flexible board, a glass board, and a paper board. The base material may be a resin board, a glass board, or a paper board.

[0142] The substrate has wiring (antenna pattern) on its surface. The substrate has wiring (antenna pattern) formed on its surface. The substrate preferably has a substrate and wiring (antenna pattern) disposed on the surface of the substrate.

[0143] Examples of the material for the substrate include resin, glass, and paper. Examples of the resin include PET (polyethylene terephthalate), PP (polypropylene), and PVC (polyvinyl chloride). The paper may be impregnated with an epoxy resin or a phenolic resin. From the viewpoint of further enhancing adhesiveness and manufacturing RFID inlays using a roll-to-roll method, the material for the substrate is preferably resin or paper, and more preferably PET (polyethylene terephthalate) or paper. The substrate may be resin, glass, or paper.

[0144] Examples of the wiring (antenna pattern) include gold wiring, nickel wiring, tin wiring, aluminum wiring, silver wiring, SUS wiring, copper wiring, molybdenum wiring, and tungsten wiring. From the viewpoint of improving the operating sensitivity in the UHF band (860 MHz to 920 MHz), the wiring is preferably aluminum wiring.

[0145] From the viewpoint of preventing deformation of the substrate due to heat when mounting a chip (e.g., an IC chip) and increasing 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.

[0146] The shapes of the substrate and the base material are not particularly limited. From the viewpoint of manufacturing RFID inlays by a roll-to-roll method, the substrate and the base material are preferably long. The lengths of the substrate and the base material are not particularly limited. The lengths of the substrate and the base material may be 1 m or more, 10 m or more, 5000 m or less, or 1000 m or less.

[0147] The surface tension of the substrate (base material) is preferably 20 mN / m or more, more preferably 30 mN / m or more, even more preferably 32 mN / m or more, particularly preferably 34 mN / m or more, and is preferably 50 mN / m or less, more preferably 48 mN / m or less, and even more preferably 45 mN / m or less. When the surface tension of the substrate (base material) is above the above lower limit and below the above upper limit, adhesion can be further improved. The conductive paste according to the present invention can be suitably used for application to a substrate (base material) having a surface tension above the above lower limit and below the above upper limit.

[0148] The surface tension of the substrate (base material) can be measured in accordance with JIS K6768 using the following method: A cotton swab is dipped in a JIS-specified liquid and applied to the substrate (base material). The surface tension is determined from the shape of the coating film 2 seconds after application.

[0149] The chip may be a semiconductor chip (IC chip) or the like.

[0150] The chip preferably has an electrode on its surface. Examples of the electrode include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, silver electrodes, SUS electrodes, copper electrodes, molybdenum electrodes, and tungsten electrodes. From the viewpoint of further improving the electrical connection reliability, the electrode is preferably a copper electrode or a gold electrode, and more preferably a copper electrode.

[0151] The number of electrodes per chip is not particularly limited, and may be 1 or more, 4 or more, 20 or less, or 10 or less.

[0152] The shape of the tip is not particularly limited, and may be rectangular, triangular, or circular.

[0153] The planar area of ​​the chip is preferably 0.04 mm 2 More than 0.09mm, preferably 0.09mm 2More preferably, 0.16 mm 2 or more, preferably 0.50 mm 2 Less than or equal to 0.40 mm, preferably 2 Less than 0.30 mm, more preferably 2 When the planar area of ​​the chip is equal to or greater than the lower limit, the conductive paste can be placed on 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 its electrical conductivity reliability even when left in a high-temperature, high-humidity environment for a long period of time. The conductive paste of the present invention can be suitably used for bonding relatively small chips.

[0154] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0155] The following materials were prepared:

[0156] (A1) Urethane (meth)acrylate: UN-9200A (manufactured by Negami Kogyo Co., Ltd., molecular weight (weight average molecular weight): 15000, viscosity: 1900000mPa s)

[0157] (A2) Polymerizable monomer: 2-Phenoxyethyl acrylate (polymerizable monomer with an aromatic skeleton, molecular weight: 192, viscosity: 10 mPa·s) Isobornyl acrylate (polymerizable monomer with an alicyclic skeleton, molecular weight: 208, viscosity: 9 mPa·s)

[0158] Curable compounds other than (A1) and (A2): UN-6306 (Negami Chemical Industrial Co., Ltd., urethane (meth)acrylate without an aromatic backbone, molecular weight (weight average molecular weight): 6500, viscosity: 190,000 mPa s) DPHA NS (Sartomer, polymerizable monomer with no aromatic or alicyclic skeleton, molecular weight (weight average molecular weight): 547, viscosity: 7800 mPa s) X-22-164 (Shin-Etsu Silicones Co., Ltd., polymerizable monomer with no aromatic or alicyclic skeleton, molecular weight (weight average molecular weight): 390, viscosity: 55 mPa·s)

[0159] (B) Conductive particles: NIELB-005-S (manufactured by Sekisui Chemical Co., Ltd., conductive particles having a base particle and a conductive portion on the surface of the base particle, nickel content in 100% by weight of conductive portion: 52% by weight, average particle diameter: 5 μm) CN050 (Nikko Rica Corporation, metal particles (nickel particles), average particle size: 5 μm) AG6-11 (DOWA Electronics, metal particles (silver particles), average particle size: 5 μm)

[0160] (C) Thermal polymerization initiator: NOF Corporation's "Perloil L"

[0161] Other Ingredients: Silica (Tokuyama "PM-20L")

[0162] Tips: IC chip (copper electrode, NXP "UCODE7", surface area: 0.22 mm 2 )

[0163] substrate: PET film ("PET" in the table, long, resin film with aluminum wiring that operates in the UHF band (860MHz to 920MHz), surface tension: 43mN / m) PP film ("PP" in the table, long, resin film with aluminum wiring that operates in the UHF band (860MHz to 920MHz), surface tension: 22mN / m)

[0164] Example 1 (1) Preparation of conductive paste The materials shown in Table 1 below were mixed in the amounts shown in Table 1 below and stirred using a planetary mixer (Thinky Corporation's "Awatori Rentaro") to obtain a conductive paste (anisotropic conductive paste).

[0165] (2) RFID inlay fabrication The obtained conductive paste was applied to a PET film by a dispense method to form a conductive paste layer (adhesive layer) (first placement step). Next, an IC chip was laminated on the surface opposite the substrate (base material) of the conductive paste layer (adhesive layer) so that the wiring on the PET film surface and the electrodes on the chip surface faced each other (second placement step). Thereafter, thermocompression bonding was performed under conditions of an upper heat tool temperature of 180°C, a lower heat tool temperature of 175°C, a pressure of 2N, and a compression time of 7 seconds to harden the conductive paste layer (adhesive layer) and form an adhesive. In addition, the wiring on the surface of the PET film and the electrodes on the surface of the chip were electrically connected by conductive particles in the adhesive to obtain a connection structure (adhesion step). The first placement step, the second placement step, and the adhesion step were performed using a "DDA40000" manufactured by Muhlbauer. The resulting connection structure was cut into a size of 5 cm x 1.5 cm using a "DCL30000" manufactured by Muhlbauer to obtain an RFID inlay.

[0166] (Examples 2 to 8 and Comparative Examples 1 to 4) Conductive pastes and RFID inlays were obtained in the same manner as in Example 1, except that the blending components and contents of the conductive paste and the type of substrate (base material) were changed as shown in Tables 1 to 3.

[0167] (evaluation) (1) Viscosity at 25°C The viscosity of the obtained conductive paste was measured at 25°C and 5 rpm using an E-type viscometer ("TV22 Viscometer" manufactured by Toki Sangyo Co., Ltd.) Note that the viscosity of the conductive paste obtained in Comparative Example 2 could not be measured because it was not mixed uniformly.

[0168] (2) Adhesion (storage modulus) The obtained conductive paste was heated at 150°C for 10 minutes to prepare a measurement sample A (cured product) having a length of 10 mm, a width of 1 to 10 mm, and a thickness of 15 to 50 mm. The storage modulus of measurement sample A was measured at 25°C using the method described above. The adhesiveness (storage modulus) was evaluated based on the storage modulus of the obtained cured product at 25°C according to the following criteria. Note that the storage modulus of the conductive paste obtained in Comparative Example 2 could not be measured because it was not mixed uniformly.

[0169] [Adhesion (storage modulus) criteria] ○○: Storage modulus is 1.5 GPa or more and 3.0 GPa or less ○: Storage modulus is 0.7 GPa or more and less than 1.5 GPa ×: Storage modulus is less than 0.7 GPa or more than 3.0 GPa

[0170] (3) Adhesion (die shear strength) The die shear strength of the obtained RFID inlay was evaluated at 25°C by peeling the chip from the substrate using a die shear tester (Nordson's "DAGE4000PLUS") at a tool height of 30 μm and a speed of 100 μm / sec. The adhesiveness (die shear strength) was evaluated according to the following criteria. Note that the conductive paste obtained in Comparative Example 2 was not mixed uniformly, so the die shear strength could not be measured.

[0171] [Adhesion (die shear strength) criteria] ○○: Die shear strength is 7.0N or more ○: Die shear strength is 4.0N or more and less than 7.0N ×: Die shear strength is less than 4.0 N

[0172] (4) Conduction reliability The obtained RFID inlay was placed in a dark box that blocks external radio waves, and the peak sensitivity at 25°C in the UHF band (860 MHz to 920 MHz) was measured using a frequency reader (Voyantic's "Tagformance Pro"), which was used to determine the initial peak sensitivity. The peak sensitivity at 25°C in the UHF band was also measured after leaving the obtained RFID inlay at 85°C and 85% humidity (high temperature and humidity environment) for 72 hours, 168 hours, and 500 hours. The conductivity reliability was evaluated according to the following criteria: initial, after leaving in a high temperature and humidity environment for 72 hours, after leaving in a high temperature and humidity environment for 168 hours, and after leaving in a high temperature and humidity environment for 500 hours.

[0173] [Initial conduction reliability criteria] ○○: Peak sensitivity is less than -18dBm ○: Peak sensitivity is -18dBm or more and less than -17dBm ×: Peak sensitivity is -17dBm or more

[0174] [Criteria for determining electrical continuity reliability after exposure to high temperature and humidity conditions (72 hours, 168 hours, and 500 hours)] XX: The absolute value of the difference from the initial peak sensitivity is less than 2 dBm, and the peak sensitivity is less than -17 dBm ○: The absolute value of the difference from the initial peak sensitivity is 2 dBm or more but less than 3 dBm, and the peak sensitivity is less than -17 dBm ×: The absolute value of the difference from the initial peak sensitivity is 3 dBm or more, or the peak sensitivity is -17 dBm or more (at least one of the ranges is satisfied)

[0175] The composition of the conductive paste, the configuration of the RFID inlay, and the results are shown in Tables 1 to 3 below.

[0176] [Table 1]

[0177] [Table 2]

[0178] Table 3

Claims

1. a curable compound, a plurality of conductive particles, and a thermal polymerization initiator; the curable compound contains a urethane (meth)acrylate having a molecular weight of 1000 or more and having an aromatic skeleton, and a polymerizable monomer having a molecular weight of less than 1000 and having an aromatic skeleton or an alicyclic skeleton, The viscosity of the conductive paste at 25°C is 5 Pa s or more and 50 Pa s or less, A conductive paste, wherein the content of the conductive particles is 3 parts by weight or more and 30 parts by weight or less relative to 100 parts by weight of the curable compound in the conductive paste.

2. A composition comprising a curable compound, a plurality of conductive particles, and a thermal polymerization initiator, the curable compound contains a urethane (meth)acrylate having a molecular weight of 1000 or more and having an aromatic skeleton, and a polymerizable monomer having a molecular weight of less than 1000 and having an aromatic skeleton or an alicyclic skeleton, The viscosity of the conductive paste at 25°C is 5 Pa s or more and 50 Pa s or less, the conductive particle comprises a base particle and a conductive portion disposed on a surface of the base particle, The conductive paste, wherein the conductive portion contains nickel.

3. A curable composition comprising a curable compound, a plurality of conductive particles, and a thermal polymerization initiator, the curable compound contains a urethane (meth)acrylate having a molecular weight of 1000 or more and having an aromatic skeleton, and a polymerizable monomer having a molecular weight of less than 1000 and having an aromatic skeleton or an alicyclic skeleton, The viscosity of the conductive paste at 25°C is 5 Pa s or more and 50 Pa s or less, A conductive paste, wherein a cured product obtained by heating the conductive paste at 150°C for 10 minutes has a storage modulus at 25°C of 0.7 GPa or more and 3.0 GPa or less.

4. The conductive paste according to any one of claims 1 to 3, wherein the conductive particles have a particle diameter of 10 µm or less.

5. The conductive paste according to any one of claims 1 to 3, which is applied to a substrate having a surface tension of 20 mN / m or more and 50 mN / m or less.

6. Plane area is 0.50 mm ２ The conductive paste according to any one of claims 1 to 3, which is used for bonding a chip that is:

7. The conductive paste according to any one of claims 1 to 3, used to obtain an RFID inlay.

8. The semiconductor device includes a substrate having wiring on its surface, a chip, and an adhesive portion that bonds the substrate and the chip together, The material of the adhesive portion is the conductive paste according to any one of claims 1 to 3, An RFID inlay, wherein the wiring and the chip are electrically connected by the conductive particles in the adhesive portion.

9. a first disposing step of disposing the conductive paste according to any one of claims 1 to 3 on a surface of a substrate having wiring on its surface; a second placement step of placing a chip on a surface of the conductive paste opposite to the substrate side; A method for manufacturing an RFID inlay, comprising: a bonding process in which an adhesive joint that bonds the substrate and the chip is formed using the conductive paste by heating and pressurizing the conductive paste, and the wiring and the chip are electrically connected by the conductive particles in the adhesive joint.

10. The substrate is long, The method for manufacturing an RFID inlay according to claim 9 , wherein the RFID inlay is manufactured by transporting the long substrate using a roll-to-roll method in the first placement step, the second placement step, and the bonding step.

11. The conductive paste according to any one of claims 1 to 3 has a surface area of ​​0.50 mm ２ Used for gluing chips that are:

12. Use of the conductive paste according to any one of claims 1 to 3 for obtaining an RFID inlay.

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