Electrically conductive paste, cured product, sintering accelerator, and sintering acceleration method

Abstract

A conductive paste comprising: silver-containing particles; and a sintering accelerator that promotes the sintering of the silver-containing particles together, wherein the sintering accelerator comprises a compound represented by formula (1) or formula (2). In formula (1), m is an integer of 1 or more and 20 or less. In formula (2), n is an integer of 1 or more and 20 or less.

Description

Technical Field

[0001] This invention relates to a conductive paste, a hardener, a sintering accelerator, and a sintering accelerator method. Prior Technology

[0002] Electronic components such as semiconductor devices are mounted on a substrate via an adhesive layer. Sometimes, this adhesive layer is required to be conductive. In such cases, a conductive adhesive layer is sometimes formed, for example, from a resin composition containing silver particles.

[0003] As a resin composition used to make conductive paste, a resin composition containing silver particles is sometimes used, for example. As a technology related to such a resin composition, the one described in Patent Document 1 can be cited as an example. Patent Document 1 describes a thermosetting resin composition comprising (A) plate-shaped silver microparticles, (B) silver powder with an average particle size of 0.5 to 30 μm, and (C) a thermosetting resin, in which conductivity is exhibited by the formation of contact points between the silver particles. [Previous Technical Documents] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2014-194013 Summary of the Invention

[0005] [The problem that the invention aims to solve]

[0006] However, in recent years, the conductivity requirements for conductive pastes have increased to a level that is no longer sufficient to meet these requirements using conventional techniques. [Technical means to solve the problem]

[0007] According to the present invention, a conductive paste, a hardener, a sintering accelerator, and a sintering accelerator method are provided as shown below. [1] A conductive paste comprising: Containing silver particles; and Sintering accelerator, which promotes the sintering of the aforementioned silver-containing particles together. The aforementioned sintering accelerators include compounds represented by formula (1) or formula (2). In equation (1), m is an integer greater than 1 and less than 20. In equation (2), n is an integer greater than 1 and less than 20. [2] The conductive paste described above [1] contains a sintering accelerator comprising a compound represented by formula (1), where m is an integer greater than or equal to 1 and less than or equal to 11. [3] The conductive paste as described in [1] or [2] above, wherein the aforementioned sintering accelerator includes the compound represented by formula (2), in which n is an integer of 2 or more and 13 or less. [4] The conductive paste of any one of [1] to [3] above, wherein the silver-containing particles include one or more of the group consisting of spherical particles, scale-like particles, aggregated particles and polyhedral-shaped particles. [5] The conductive paste described above [4] contains silver particles selected from two or more of the group consisting of spherical particles, scale-like particles, aggregated particles, and polyhedral-shaped particles. [6] The conductive paste, such as any one of [1] to [5] above, further comprises an epoxy monomer. [7] The conductive paste described above [6] further contains a phenolic curing agent. [8] The conductive paste described above in [6] or [7] further contains an imidazole curing accelerator. [9] The conductive paste of any of [1] to [8] above further comprises (meth)acrylic acid monomer.

[10] The conductive paste described above [9] further contains a free radical polymerization initiator.

[11] The conductive paste, such as any of [1] to

[10] above, further comprises a solvent.

[12] In the case of a conductive paste as described in any of [1] to

[11] above, where the conductive paste is applied to a glass plate with a thickness of 0.05 mm after sintering, and the plate is heated from 30°C to 200°C for 60 minutes in a nitrogen environment, and then sintered at 200°C for 120 minutes to obtain a hardened material, the volume resistivity of the hardened material is 4.0 μΩ·cm or more and 9.5 μΩ·cm or less.

[13] A hardened material obtained by sintering any of the conductive pastes described in [1] to

[12] above.

[14] A sintering accelerator that promotes the sintering of silver-containing particles together, comprising a compound represented by formula (1) or formula (2). In equation (1), m is an integer greater than 1 and less than 20. In equation (2), n is an integer greater than 1 and less than 20.

[15] A sintering promotion method, which uses the sintering promoter described above

[14] to promote the sintering of silver-containing particles. [Effects of the Invention]

[0008] According to the present invention, a conductive paste with excellent conductivity is provided. Simple Explanation of the Diagram

[0009] [Figure 1] is a cross-sectional view of a semiconductor device having an adhesive layer formed from the conductive paste of this embodiment. [Figure 2] is a SEM image of the cross section of the hardened material formed from the conductive paste of Example 2. [Figure 3] is a SEM image of the cross-section of the hardened material formed from the conductive paste of Comparative Example 1. Implementation

[0010] Hereinafter, embodiments of the present invention will be described using drawings. Furthermore, in all drawings, the same symbols are used to denote the same constituent elements, and descriptions are omitted where appropriate. Also, unless otherwise specified, "a~b" indicates "a or more and b or less".

[0011] [Conductive paste] <An Overview of Sintering Technology> The conductive paste in this embodiment is a sintered conductive paste. First, an overview of the sintering technology will be given.

[0012] In sintered conductive pastes, conductivity is ensured by sintering metal particles during the sintering process. That is, due to heat, the interfaces between metal particles disappear, and the metal particles sinter together, forming a sintered structure (metal particle interconnection structure). This sintered structure then functions as a conductive path.

[0013] In sintered conductive pastes, resin components are typically incorporated as a binder. A fully sintered paste is one where the resin completely evaporates during the sintering process, leaving no resin residue in the hardened product. Conversely, a semi-sintered paste is one where only a portion of the resin evaporates during the sintering process, leaving resin residue in the hardened product.

[0014] In semi-sintered conductive paste, the resin component remaining in the hardened material plays a role in ensuring close contact between the sintered structure (metal particle linkage structure) and the substrate.

[0015] Figure 1 provides an overview of the adhesive layer formed from sintered conductive paste.

[0016] Figure 1 is a cross-sectional view of a semiconductor device 100 having an adhesive layer formed from the conductive paste of this embodiment. In the semiconductor device 100, an adhesive layer 10 is formed by coating a conductive paste of the present embodiment onto the surface of a substrate 30. Then, a semiconductor element 20 is mounted on the surface of the substrate 30 via the adhesive layer 10.

[0017] After the semiconductor device 20 is loaded via the aforementioned bonding layer 10, the silver-containing particles contained in the bonding layer 10 are sintered by sintering.

[0018] Subsequently, the semiconductor element 20 and the substrate 30 are electrically connected by bonding wires 40 and then sealed by molding resin 50. Then, a plurality of solder balls 60 are formed on the back side of the substrate 30 opposite to the surface on which the semiconductor element 20 is mounted, thereby forming the semiconductor device 100.

[0019] <Characteristics of the conductive paste in this embodiment> The conductive paste of this embodiment contains: Containing silver particles; and Sintering accelerator, which promotes the sintering of the aforementioned silver-containing particles together. The above-mentioned sintering accelerators include compounds represented by formula (1) or formula (2). In equation (1), m is an integer greater than 1 and less than 20. In equation (2), n is an integer greater than 1 and less than 20.

[0020] The adhesive layer formed by the conductive paste of this embodiment has good conductivity.

[0021] SEM observation of the cross-section of the hardened material formed from the conductive paste of this embodiment confirms that more silver-containing particles have fused together, thus promoting sintering. It is believed that by promoting sintering in this way, electrical and thermal conductivity are improved.

[0022] <Each ingredient> The components contained in the conductive paste of this embodiment will be described below.

[0023] (Sintering accelerator) Sintering accelerators refer to agents that promote the sintering of metal particles.

[0024] The conductive paste of this embodiment contains a sintering accelerator, thus promoting the sintering of silver-containing particles compared to conductive pastes without a sintering accelerator. It is believed that by promoting sintering in this way, electrical and thermal conductivity are improved.

[0025] Previously, no agent that promotes the sintering of metal particles had been found in the field of conductive pastes. However, through various investigations, the inventors discovered an agent that promotes the sintering of metal particles, thus completing this invention.

[0026] Although the mechanism by which the sintering accelerator of this embodiment promotes sintering is not yet clear, it is speculated that the sintering accelerator of this embodiment acts on the surface of silver particles, thereby improving the dispersion of silver particles. As a result, it promotes the fusion and material movement at the contact interface between silver particles, thereby promoting sintering.

[0027] The sintering accelerator of this embodiment may contain one or more compounds represented by formula (1) or formula (2). In equation (1), m is an integer greater than 1 and less than 20. In equation (2), n is an integer greater than 1 and less than 20.

[0028] The sintering accelerator of this embodiment is characterized by having an ethylene glycol structure or a propylene glycol structure. The inventors hypothesize that these structures interact with the surface of the silver-containing particles to improve the dispersibility of the particles.

[0029] In the above formula (1), m is an integer of 1 or more, preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, and m is an integer of 20 or less, preferably 11 or less, more preferably 10 or less, and even more preferably 9 or less. With m within the above range, the dispersibility of silver-containing particles is further improved, and the conductivity and thermal conductivity of the adhesive layer formed by the conductive paste are further improved. In the above formula (2), n is an integer greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, and greater than or equal to 4; and n is less than or equal to 20, less than or equal to 13, less than or equal to 12, and less than or equal to 11. With n within the above range, the dispersibility of silver-containing particles is further improved, and the conductivity and thermal conductivity of the adhesive layer formed by the conductive paste are further improved.

[0030] Specific examples of sintering accelerators in this embodiment include: KYOEISHA CHEMICAL Co., Ltd. manufactures EPOLITE40E (ethylene glycol diglycidyl ether), EPOLITE100E (diethylene glycol diglycidyl ether), EPOLITE400E (polyethylene glycol diglycidyl ether), EPOLITE70P (polypropylene glycol diglycidyl ether), EPOLITE200P (tripropylene glycol diglycidyl ether), and EPOLITE400P (polypropylene glycol diglycidyl ether). Nagase ChemteX Corporation manufactures DENACOL EX-810 (ethylene glycol diglycidyl ether), DENACOL EX-821 (polyethylene glycol diglycidyl ether), DENACOL EX-830 (polyethylene glycol diglycidyl ether), DENACOL EX-920 (polypropylene glycol diglycidyl ether), and DENACOL EX-931 (polypropylene glycol diglycidyl ether), among others.

[0031] The conductive paste of this embodiment may contain only one sintering accelerator or two or more sintering accelerators.

[0032] Regarding the content of the sintering accelerator in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by mass, it is suitable to be 0.5 parts by mass or more, more suitable to be 0.7 parts by mass or more, and even more suitable to be 1.0 parts by mass or more. This further promotes the sintering of the silver-containing particles.

[0033] Furthermore, regarding the content of the sintering accelerator in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 50 parts by weight or less, more suitable to be 20 parts by weight or less, and even more suitable to be 10 parts by weight or less. This results in a better balance of properties such as heat cycle resistance and adhesion to the substrate.

[0034] (Contains silver particles) The conductive paste of this embodiment contains silver particles.

[0035] Silver-containing particles undergo sintering through appropriate heat treatment during the sintering process, forming a particle-linked structure (sintered structure).

[0036] There are no particular restrictions on the shape of the silver-containing particles in this embodiment.

[0037] The silver-containing particles in this embodiment preferably include one or more types selected from the group consisting of spherical particles, scale-like particles, aggregated particles, and polyhedral-shaped particles.

[0038] In this embodiment, it is more preferable to include two or more types of silver-containing particles selected from spherical particles, flake-like particles, aggregated particles, and polyhedral-shaped particles. More preferably, it includes spherical silver-containing particles b1 and silver-containing particles b2 selected from one or more types of flake-like, aggregated, and polyhedral shapes. Most preferably, it includes spherical silver-containing particles b1 and flake-like silver-containing particles b2-1. This further increases the contact rate between the silver-containing particles, thus facilitating the formation of a network after sintering the conductive paste, thereby further improving thermal and electrical conductivity.

[0039] By using silver-containing particles, including silver-containing particles b2, it is possible to suppress resin cracking in molded articles obtained from conductive paste, or to suppress the increase in the coefficient of linear expansion. Furthermore, in this embodiment, "spherical" is not limited to a perfect sphere, but also includes shapes with several irregularities on the surface. Its roundness is, for example, 0.90 or higher, preferably 0.92 or higher, and even more preferably 0.94 or higher.

[0040] The median particle size D50 of the silver-containing particles is, for example, 0.01 μm or more and 50 μm or less, preferably 0.1 μm or more and 20 μm or less, and even more preferably 0.5 μm or more and 10 μm or less. By setting the median particle size D50 to an appropriate value, it is easy to maintain a balance of thermal conductivity, sinterability, and resistance to thermal cycling. Furthermore, by setting D50 to an appropriate value, it is sometimes possible to improve the workability of coating / adhesion. The particle size distribution of silver-containing particles (horizontal axis: particle size, vertical axis: frequency) can be unimodal or multimodal.

[0041] From the viewpoint of the effectiveness of the present invention, the silver-containing particles preferably include spherical silver-containing particles b1 and scaly silver-containing particles b2-1. These silver-containing particles are more preferably silver particles composed substantially only of silver.

[0042] The median particle size D50 of the spherical silver-bearing particles b1 is, for example, 0.1~20 μm, preferably 0.5~10 μm, and more preferably 0.5~5.0 μm. The specific surface area of ​​the spherical silver-containing particles b1 is, for example, 0.1~2.5 m² / g, preferably 0.5~2.3 m² / g, and more preferably 0.8~2.0 m² / g. The tap density of the spherical silver-containing particles b1 is, for example, 1.5~6.0 g / cm³, preferably 2.5~5.8 g / cm³, and even more preferably 4.5~5.5 g / cm³. The spherical silver-containing particles b1 have a roundness of, for example, 0.90 or higher, preferably 0.92 or higher, and even more preferably 0.94 or higher. By satisfying these various characteristics, it achieves an excellent balance of thermal conductivity, sinterability, and resistance to thermal cycling.

[0043] The median particle size D50 of the scaly silver-bearing particles b2-1 is, for example, 0.1~20 μm, preferably 1.0~15 μm, and more preferably 2.0~10 μm. The specific surface area of ​​the scaly silver-containing particles b2-1 is, for example, 0.1~2.5 m² / g, preferably 0.2~2.0 m² / g, and more preferably 0.25~1.2 m² / g. The tap density of the scaly silver-containing particles b2-1 is, for example, 1.5~6.0 g / cm3, preferably 2.5~5.9 g / cm3, and more preferably 4.0~5.8 g / cm3. By satisfying these various characteristics, it achieves an excellent balance of thermal conductivity, sinterability, and resistance to thermal cycling.

[0044] In this embodiment, by combining at least one spherical silver-containing particle b1 that satisfies at least one of the above-mentioned characteristics and at least one scale-shaped silver-containing particle b2-1 that satisfies at least one of the above-mentioned characteristics, the thermal conductivity and electrical conductivity are particularly improved.

[0045] The ratio (b1 / b2-1) of the content of spherical silver-containing particles b1 to the content of flake-shaped silver-containing particles b2-1 is preferably 0.1 or more and 10 or less, more preferably 0.3 or more and 5 or less, and most preferably 0.5 or more and 3 or less. This significantly increases the contact rate between the silver-containing particles, making it easier to form a network after sintering the conductive paste, thus particularly improving thermal and electrical conductivity.

[0046] The ratio (b1 / b2-1) of the median particle size D50 of the spherical silver-bearing particles b1 to the median particle size D50 of the flake-like silver-bearing particles b2-1 is preferably 0.01 or more and 0.8 or less, and more preferably 0.05 or more and 0.6 or less. In this way, spherical silver-containing particles are efficiently filled into the gaps between the scale-like silver-containing particles, thereby significantly improving the contact rate between the silver-containing particles. As a result, a network is easily formed after the conductive paste is sintered, and the thermal conductivity and electrical conductivity are particularly improved.

[0047] The ratio of the tap density of the spherical silver-bearing particles b1 to the tap density of the flake-shaped silver-bearing particles b2-1 (b1 / b2-1) is preferably 0.5 or more and 2.0 or less, and more preferably 0.7 or more and 1.2 or less. This increases the filling rate of silver particles, thereby significantly improving the contact rate between the silver particles. As a result, the conductive paste is more likely to form a network after sintering, thus significantly improving its thermal and electrical conductivity.

[0048] The median particle size D50 of silver-containing particles can be determined, for example, by particle image measurement using the FPIA (registered trademark)-3000 flow particle image analyzer manufactured by Sysmex Corporation. More specifically, the particle size of silver-containing particles can be determined by measuring the median particle size on a volumetric basis using this apparatus in a wet manner.

[0049] Regarding the content of silver particles in the conductive paste of this embodiment, when all non-volatile components of the conductive paste are set to 100 parts by mass, it is suitable to be 40 parts by mass or more, more suitable to be 60 parts by mass or more, and even more suitable to be 80 parts by mass or more. This further improves electrical and thermal conductivity.

[0050] Furthermore, regarding the silver particle content in the conductive paste of this embodiment, when all non-volatile components of the conductive paste are set to 100 parts by mass, it is suitable to be 98 parts by mass or less, more suitable to be 97 parts by mass or less, and even more suitable to be 96 parts by mass or less. This results in an excellent balance of thermal conductivity, sintering properties, adhesion to the substrate, and resistance to thermal cycling.

[0051] Silver-containing particles can be (i) particles that are essentially composed of only silver, or (ii) particles that are composed of silver and other components besides silver. Furthermore, (i) and (ii) can be used together as metallic-containing particles.

[0052] As (i) a particle that is essentially composed only of silver, for example, a silver particle can be cited.

[0053] (ii) Particles composed of silver and other components besides silver, for example, silver-coated resin particles. Silver-coated resin particles are particles whose surface is coated with silver. Silver-coated resin particles with a silver-coated surface have good thermal conductivity and are softer than particles composed of silver alone. Therefore, by using silver-coated resin particles, it is easy to set the thermal conductivity and storage modulus to appropriate values.

[0054] In silver-coated resin particles, the silver layer only needs to cover at least a portion of the surface of the resin particles. Of course, the silver can also cover the entire surface of the resin particles.

[0055] Specifically, in silver-coated resin particles, the silver layer preferably covers more than 50%, more preferably more than 75%, and even more preferably more than 90% of the surface of the resin particles. Most preferably, in silver-coated resin particles, the silver layer substantially covers the entire surface of the resin particles. As another point of view, when cutting a silver-coated resin particle at a certain cross section, it is preferable to confirm the silver layer around the entire perimeter of that cross section.

[0056] As another point of view, the mass ratio of resin to silver in the silver-coated resin particles is, for example, 90 / 10 to 10 / 90, preferably 80 / 20 to 20 / 80, and even more preferably 70 / 30 to 30 / 70.

[0057] Examples of "resin" used in silver-coated resin particles include polysiloxane resin, (meth)acrylic resin, phenolic resin, polystyrene resin, melamine resin, polyamide resin, and polytetrafluoroethylene resin. Of course, other resins may also be used. Furthermore, there may be only one type of resin, or two or more types of resin may be used together. From the perspective of elasticity and heat resistance, polysiloxane or (meth)acrylic resins are preferred.

[0058] (i) Particles that are essentially composed of only silver can be obtained, for example, from DOWA HIGHTECH Co., Ltd., Fukuda Metal Foil & Powder Co., Ltd.

[0059] Furthermore, (ii) silver-coated resin particles composed of silver and other components can be obtained, for example, from Mitsubishi Materials Corporation, SEKISUI CHEMICAL Co., Ltd., SANNO Co., Ltd., etc.

[0060] (Other ingredients) The conductive paste of this embodiment may contain components other than sintering accelerators and silver particles.

[0061] ·Epoxy monomers The conductive paste of this embodiment is suitable for containing epoxy monomers.

[0062] The epoxy monomer in this embodiment has an epoxy group in its structure.

[0063] The epoxy monomer of this embodiment can be a monofunctional epoxy monomer having only one epoxy group in its structure, or a polyfunctional epoxy monomer having two or more epoxy groups in its structure.

[0064] Examples of monofunctional epoxy monomers include 4-tert-butylphenyl epoxypropyl ether, m-cresol epoxypropyl ether, p-cresol epoxypropyl ether, phenyl epoxypropyl ether, and cresol epoxypropyl ether.

[0065] Examples of multifunctional epoxy monomers include: bisphenol compounds such as bisphenol A, bisphenol F, and biphenol, or their derivatives; diols with alicyclic structures such as hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, cyclohexanediethanol, and cyclohexanediethanol, or their derivatives; difunctional monomers obtained by epoxidation of aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, and decanediol, or their derivatives; trifunctional monomers having a trimethylolpropane skeleton, a trihydroxyphenylmethane skeleton, or an aminophenol skeleton; and multifunctional monomers obtained by epoxidation of phenolic varnish resins, cresol phenolic varnish resins, phenol aralkyl resins, biphenyl aralkyl resins, and naphthol aralkyl resins.

[0066] Regarding the epoxy monomer content in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 0.5 parts by weight or more, more suitable to be 0.7 parts by weight or more, and even more suitable to be 1.0 parts by weight or more. This results in a better balance of properties such as heat cycle resistance and adhesion to the substrate.

[0067] Furthermore, regarding the content of epoxy monomers in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 50 parts by weight or less, more suitable to be 20 parts by weight or less, and even more suitable to be 10 parts by weight or less.

[0068] (Meth)acrylic acid monomer The conductive paste of this embodiment is suitable for containing (meth)acrylic acid monomers.

[0069] The acrylic monomer in this embodiment is a monomer having a (meth)acrylic acid group in its structure.

[0070] The acrylic monomer of this embodiment can be a monofunctional acrylic monomer having only one (meth)acrylic acid group in its structure, or a polyfunctional acrylic monomer having two or more (meth)acrylic acid groups in its structure.

[0071] In this embodiment, (meth)acrylate group is a concept that includes (meth)acrylate ester group. Furthermore, in this embodiment, (meth)acrylate group represents both acrylic and methacrylate groups, and (meth)acrylic group represents both acrylonitrile and methacrylic group.

[0072] Examples of monofunctional acrylic monomers include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, butoxyethyl methacrylate, pentyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, heptyl methacrylate, octylheptyl methacrylate, nonyl methacrylate, and so on. Aliphatic (meth)acrylates include decyl acrylate, undecyl acrylate, lauryl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, stearyl acrylate, dodecyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, and phenoxy polyethylene glycol (meth)acrylate. Cyclopentyl methacrylate, cyclohexyl methacrylate, 1,4-cyclohexanediethanol mono(meth)acrylate, cyclopentyl methacrylate, dicyclopentyl methacrylate, dicyclopentenyl methacrylate, isoborneol methacrylate, 3-methyl-3-oxetanebutylmethyl(meth)acrylate, 1-adamantyl(meth)acrylate, and other alicyclic (meth)acrylates; Aromatic (meth)acrylates include phenyl acrylate, nonylphenyl (meth)acrylate, p-isopropylphenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl (meth)acrylate, and 2-hydroxy-3-(2-naphthoxy)(meth)acrylate. Heterocyclic (meth)acrylates such as 2-tetrahydrofurfuryl acrylate, N-(meth)propenyloxyethyl hexahydrophthalimide, and 2-(meth)propenyloxyethyl-N-carbazole.

[0073] Examples of difunctional acrylic monomers include, for example: ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 2-methyl... Aliphatic dimethacrylates include methyl-1,3-propanediol dimethacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 3-methyl-1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, and glycerol dimethacrylate. Cyclohexanediethanol di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol F di(meth)acrylate, and other alicyclic di(meth)acrylates; Aromatic dimethacrylates such as bisphenol A dimethacrylate, bisphenol F dimethacrylate, bisphenol AF dimethacrylate, ethoxylated bisphenol A dimethacrylate, and ephemeral dimethacrylate; Heterocyclic di(meth)acrylates such as isocyanurate di(meth)acrylate.

[0074] Examples of acrylic monomers with three or more functionalities include, for example, trimethylolpropane tri(meth)acrylate, neopentyl tert-methacrylate, di-trimethylolpropane tetra(meth)acrylate, neopentyl tert-methacrylate, dinepentyl tert-methacrylate, dinepentyl tert-methacrylate, dinepentyl tert-methacrylate, ethoxylated glycerol tri(meth)acrylate, and other aliphatic (meth)acrylates. Heterocyclic (meth)acrylates such as isocyanurate tri(meth)acrylate.

[0075] Regarding the content of (meth)acrylic acid monomer in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 0.3 parts by weight or more, more suitable to be 0.5 parts by weight or more, and even more suitable to be 0.6 parts by weight or more. This results in a better balance of properties such as heat cycle resistance and adhesion to the substrate.

[0076] Furthermore, regarding the content of (meth)acrylic acid monomer in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by mass, it is suitable to be 50 parts by mass or less, more suitable to be 20 parts by mass or less, and even more suitable to be 10 parts by mass or less.

[0077] Hardener When the conductive paste of this embodiment includes epoxy monomers and epoxy resin, it is preferable that the conductive paste of this embodiment also includes a hardener. This allows the epoxy monomers and epoxy resin to harden and shrink, thereby causing the silver-containing particles to aggregate.

[0078] Regarding the content of the hardener in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 0.5 parts by weight or more, more suitable to be 1.0 parts by weight or more, and even more suitable to be 1.2 parts by weight or more. This results in a better balance of properties such as heat cycle resistance and adhesion to the substrate.

[0079] Furthermore, regarding the content of the hardener in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 50 parts by weight or less, more suitable to be 20 parts by weight or less, and even more suitable to be 10 parts by weight or less.

[0080] The conductive paste of this embodiment is suitable for containing a phenolic curing agent.

[0081] Examples of phenolic curing agents include phenolic varnish resins such as phenolic resin, cresol phenolic resin, bisphenol phenolic resin, and phenol-biphenyl phenolic resin; polyvinylphenol; triphenylmethane-type phenolic resins; terpene-modified phenolic resins and dicyclopentadiene-modified phenolic resins; phenolic aralkyl resins with an extended phenyl skeleton and / or a co-extended phenyl skeleton, and naphthol aralkyl resins with an extended phenyl skeleton; bisphenol compounds such as bisphenol A and bisphenol F (dihydroxydiphenylmethane); and compounds with a co-extended phenyl skeleton such as 4,4'-biphenyl.

[0082] Hardening accelerator The conductive paste of this embodiment may contain epoxy monomers or epoxy resins and a curing accelerator to promote the reaction with the curing agent.

[0083] Examples of hardening accelerators include: imidazole-based hardening accelerators; compounds containing phosphorus atoms such as organophosphorus compounds, tetrasubstituted phosphonium compounds, phosphobetaine compounds, adducts of phosphonium compounds and quinone compounds, adducts of phosphonium compounds and silane compounds; dicyandiamine, 1,8-diazabicyclo[5.4.0]-undecene-7, benzyl dimethylamine, and other amidines and tertiary amines; and compounds containing nitrogen atoms such as quaternary ammonium salts of the aforementioned amidines or tertiary amines.

[0084] Regarding the content of the curing accelerator in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 0.01 parts by weight or more, more suitable to be 0.05 parts by weight or more, and even more suitable to be 0.07 parts by weight or more. This results in a better balance of properties such as heat cycle resistance and adhesion to the substrate.

[0085] Furthermore, regarding the content of the curing accelerator in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by weight, it is suitable to be 10 parts by weight or less, and more suitable to be 5 parts by weight or less.

[0086] The conductive paste of this embodiment is suitable for containing an imidazole-based curing accelerator.

[0087] Examples of imidazole-based hardening accelerators include 2-phenyl-1H-imidazol-4,5-diethanol, 2-phenyl-4-methyl-5-hydroxymethylimidazol, 2-methylimidazol, 2-phenylimidazol, 2,4-diamine-6-[2-methylimidazolyl-(1)]-ethyl-symmetric triazine, 2-undecylimidazol, 2-heptadecylimidazol, 2,4-diamine-6-[2-methylimidazolyl-(1)]-ethyl-symmetric triazine isocyanate adduct, 2-phenylimidazol isocyanate adduct, 2-methylimidazol isocyanate adduct, 1,2,4-benzenedric acid 1-cyanoethyl-2-phenylimidazolium, 1,2,4-benzenedric acid 1-cyanoethyl-2-undecylimidazolium, etc.

[0088] Free radical polymerization initiators When the conductive paste of this embodiment contains (meth)acrylic acid monomers, the conductive paste of this embodiment preferably contains a free radical polymerization initiator. This allows the (meth)acrylic acid monomers to harden and shrink, thereby causing the silver-containing particles to aggregate.

[0089] As free radical polymerization initiators, azo compounds, peroxides, etc., can be used, for example. In the specific examples above, peroxides are preferred, for example.

[0090] Examples of the aforementioned peroxides include, for example, diacyl peroxides, dialkyl peroxides, and peroxy ketals; more specifically, examples include ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; and peroxy ketals such as 1,1-bis(tert-butylperoxy)cyclohexane and 2,2-bis(4,4-bis(tert-butylperoxy)cyclohexyl)propane. Hydroperoxides such as menthol hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and tert-butyl hydroperoxide; Di(2-tert-butylperoxyisopropyl)benzene, diisopropylphenyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylisopropylphenyl peroxide, di-tert-hexyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-3, di-tert-butyl peroxide and other dialkyl peroxides; Diphenylmethane peroxide, di(4-methylbenzoyl) peroxide, and other diphenylmethane peroxides; Peroxydicarbonates such as di-n-propyl peroxydicarbonate and diisopropyl peroxydicarbonate; Peroxide esters such as 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, trihexyl peroxybenzoate, tributyl peroxybenzoate, and tributyl peroxy-2-ethylhexanoate.

[0091] Regarding the content of the free radical polymerization initiator in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by mass, it is suitable to be 0.01 parts by mass or more, more suitable to be 0.03 parts by mass or more, and even more suitable to be 0.04 parts by mass or more. This results in a better balance of properties such as heat cycle resistance and adhesion to the substrate.

[0092] Furthermore, regarding the content of the free radical polymerization initiator in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by mass, it is suitable to be 10 parts by mass or less, and more suitable to be 5 parts by mass or less.

[0093] Solvent The conductive paste of this embodiment preferably contains a solvent. This improves the flowability of the conductive paste, thus enhancing its workability.

[0094] Examples of solvents used in this embodiment include methyl carbitol, ethyl carbitol, butyl carbitol, methyl carbitol acetate, ethyl carbitol acetate, butyl carbitol acetate, acetone, methyl isobutyl ketone (MIBK), cyclohexanone, diacetone alcohol, ethyl cellulose, methyl cellulose, butyl cellulose, ethyl cellulose acetate, methyl cellulose acetate, butyl cellulose acetate, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, and decanol. Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, methyl methoxybutanol, α-terpineol, β-terpineol, γ-terpineol, terpineol (a mixture of α, β, and γ), dihydroterpineol, 2-methyl-2,4-pentanediol, benzyl alcohol, 2-phenylethanol, isopalmitol, isostearyl alcohol, lauryl alcohol, ethylene glycol, propylene glycol, or glycerol, etc. Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol (4-hydroxy-4-methyl-2-pentanone), 2-octanone, isophorone (3,5,5-trimethyl-2-cyclohexen-1-one), or diisobutyl ketone (2,6-dimethyl-4-heptanone); Esters such as ethyl acetate, butyl acetate, diethyl phthalate, dibutyl phthalate, acetoxyethane, methyl butyrate, methyl hexanoate, methyl octanoate, methyl decanoate, methyl methyl acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 1,2-diacetoxyethane, tributyl phosphate, tricresyl phosphate, or tripentyl phosphate; Ethers such as tetrahydrofuran, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, ethoxyethyl ether, 1,2-bis(2-diethoxy)ethane, or 1,2-bis(2-methoxybutoxy)ethane; Ester ethers such as 2-(2-butoxyethoxy)ethane acetate; 2-(2-methoxyethoxy)ethanol and other ether alcohols, toluene, xylene, n-alkanes, isoalkanes, dodecylbenzene, turpentine, kerosene or light oil and other hydrocarbons; Nitriles such as acetonitrile or propionitrile; Acetamides such as acetamide or N,N-dimethylformamide; Low molecular weight volatile silicone oil or volatile organic modified silicone oil, etc.

[0095] Regarding the solvent content in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by mass, it is suitable to be 1 part by mass or more, more suitable to be 2 parts by mass or more, and even more suitable to be 3 parts by mass or more.

[0096] Furthermore, regarding the solvent content in the conductive paste of this embodiment, when the conductive paste is set to 100 parts by mass, it is suitable to be 50 parts by mass or less, more suitable to be 20 parts by mass or less, and even more suitable to be 10 parts by mass or less.

[0097] Depending on the requirements, the conductive paste of this embodiment may also contain polymer components such as epoxy resin, (meth)acrylic resin, polysiloxane resin, and butadiene rubber; inorganic fillers such as silica and alumina; thixotropic modifiers such as fine silica; coupling agents; antioxidants; dispersants; defoamers; and leveling agents. The proportions of these components can be appropriately set to suit the intended use of the conductive paste.

[0098] When the conductive paste of this embodiment contains, for example, butadiene rubber among the above-mentioned components, it is preferable to have epoxy groups from the viewpoint of the reactivity of other components. Regarding the content of epoxy-containing butadiene rubber (hereinafter referred to as epoxy-containing butadiene rubber) in the conductive paste of this embodiment, from the viewpoint of reducing the storage elastic modulus of the effect obtained by the paste and improving the adhesion to the substrate, when the conductive paste is set to 100 parts by mass, it is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 parts by mass or more, and more preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. As a specific example of butadiene rubber containing epoxy groups, NISSO-PB JP-200 (epoxy-modified polybutadiene) manufactured by NIPPON SODA Co., Ltd. can be cited.

[0099] The conductive paste of this embodiment can be obtained by mixing the above-mentioned components and other components added as needed using conventionally known methods.

[0100] <Physical properties> The conductive paste of this embodiment is suitable for use in a paste form at 20°C. That is, the conductive paste of this embodiment can be applied to a substrate or the like in a paste form at 20°C. Therefore, the conductive paste of this embodiment can be preferably used as an adhesive for semiconductor devices. Of course, depending on the applicable manufacturing process, the conductive paste of this embodiment can be a varnish-like substance with relatively low viscosity.

[0101] When the conductive paste of this embodiment is coated onto a glass plate to a thickness of 0.05 mm after sintering, and a hardened material is obtained by heating from 30°C to 200°C for 60 minutes in a nitrogen atmosphere, followed by sintering at 200°C for 120 minutes, the volume resistivity of the hardened material is preferably 9.5 μΩ·cm or less, and more preferably 9.2 μΩ·cm or less. This improves the conductivity of the hardened material obtained from the conductive paste of this embodiment. Furthermore, the volume resistivity of the hardened material is typically 4.0 μΩ·cm or more, and preferably 4.5 μΩ·cm or more.

[0102] <Applications> The conductive paste of this embodiment can be used to manufacture semiconductor devices. For example, semiconductor devices can be manufactured by using the conductive paste of this embodiment as an "adhesive" between a substrate and a semiconductor element.

[0103] In other words, the semiconductor device of this embodiment includes, for example, a substrate and a semiconductor element, which is mounted on the substrate by means of an adhesive layer obtained by sintering the aforementioned conductive paste.

[0104] Examples of semiconductor components include ICs, LSIs, power semiconductor components (power semiconductors), and various other components. Examples of substrates include various semiconductor wafers, lead frames, BGA substrates, mounting substrates, heat spreaders, and heat sinks.

[0105] The following description, with reference to the figures, illustrates an example of a semiconductor device. Figure 1 is a cross-sectional view showing an example of a semiconductor device.

[0106] In the semiconductor device 100, an adhesive layer 10 is formed by coating a conductive paste of the present embodiment onto the surface of a substrate 30. Then, a semiconductor element 20 is mounted on the surface of the substrate 30 via the adhesive layer 10.

[0107] The thickness of the bonding layer 10 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. This improves the conductivity reliability of the bonding layer. Furthermore, the thickness of the bonding layer 10 is preferably 100 μm or less, and more preferably 50 μm or less.

[0108] There are no particular limitations on the method of applying conductive paste. Specifically, methods such as drop coating, printing, and inkjet printing can be cited.

[0109] After the semiconductor device 20 is loaded via the aforementioned bonding layer 10, the silver-containing particles contained in the bonding layer 10 are sintered by sintering.

[0110] Subsequently, the semiconductor element 20 and the substrate 30 are electrically connected by bonding wires 40 and then sealed by molding resin 50. Then, a plurality of solder balls 60 are formed on the back side of the substrate 30 opposite to the surface on which the semiconductor element 20 is mounted, thereby forming the semiconductor device 100.

[0111] [Hardened material] The hardened material in this embodiment is obtained by sintering the aforementioned conductive paste.

[0112] The suitable sintering temperature is above 150℃, more suitable is above 180℃, and even more suitable is above 200℃. This can further promote the sintering of silver-containing particles together.

[0113] The suitable sintering temperature is below 300℃, more suitable is below 280℃, and even more suitable is below 250℃. This allows for easy adjustment of the volatilization of monomer components during sintering, thereby facilitating the adjustment of the physical properties of the hardened material.

[0114] The volume resistivity of the cured material in this embodiment is preferably 10.0 μΩ·cm or less, more preferably 9.5 μΩ·cm or less, and even more preferably 9.2 μΩ·cm or less. This improves the conductivity of the cured material. Furthermore, the volume resistivity of the hardened material in this embodiment is typically 4.0 μΩ·cm or higher, and preferably 4.5 μΩ·cm or higher.

[0115] The storage modulus of elasticity (E') of the hardened material in this embodiment is preferably 20 GPa or less, more preferably 17 GPa or less, and even more preferably 15 GPa or less. This improves the adhesion between the hardened material and the substrate. Furthermore, the storage modulus of elasticity (E') of the hardened material in this embodiment is preferably 1.0 GPa or higher, more preferably 3.0 GPa or higher, and even more preferably 5.0 GPa or higher. This improves the strength of the hardened material.

[0116] As described above, the hardened product of this embodiment is obtained by sintering a conductive paste containing a sintering accelerator, and therefore the sintering of silver particles is accelerated compared to conventional hardened products.

[0117] SEM observation of the cross-section of the hardened material in this embodiment confirms that more silver-containing particles have fused together, indicating that sintering has been promoted. It is believed that by promoting sintering in this way, electrical and thermal conductivity are improved.

[0118] [Sintering accelerator] The sintering accelerator of this embodiment is one that promotes the sintering of silver-containing particles together, and includes the compound represented by formula (1) or formula (2). In equation (1), m is an integer greater than 1 and less than 20. In equation (2), n is an integer greater than 1 and less than 20.

[0119] Although the mechanism by which the sintering accelerator of this embodiment promotes sintering is not yet clear, it is speculated that the sintering accelerator of this embodiment acts on the surface of silver particles, thereby improving the dispersion of silver particles. As a result, it promotes the fusion and material movement at the contact interface between silver particles, thereby promoting sintering.

[0120] The sintering accelerator of this embodiment can be incorporated into various resin compositions, such as conductive paste.

[0121] The composition of the resin composition incorporating the sintering accelerator of this embodiment is not particularly limited.

[0122] The content of the sintering accelerator in the resin composition is not particularly limited. When the resin composition is set to 100 parts by weight, it is suitable to be 0.5 parts by weight or more, more suitable to be 0.7 parts by weight or more, and even more suitable to be 1.0 parts by weight or more. This further promotes the sintering of silver-containing particles.

[0123] Furthermore, regarding the content of the sintering accelerator in the resin composition, when the resin composition is set to 100 parts by weight, it is suitable to be 50 parts by weight or less, more suitable to be 20 parts by weight or less, and even more suitable to be 10 parts by weight or less. This results in a better balance of properties such as heat cycle resistance and adhesion to the substrate.

[0124] [Methods to promote sintering] The sintering promotion method of this embodiment is a method of promoting the sintering of silver-containing particles by using the above-mentioned sintering promoter.

[0125] By incorporating the above-mentioned sintering accelerators into various resin compositions, such as conductive pastes, the sintering of silver-containing particles can be promoted.

[0126] The embodiments of the present invention have been described above, but these are merely examples, and various configurations other than those described above are possible. Furthermore, the present invention is not limited to the above embodiments, and modifications and alterations that achieve the objectives of the present invention are included within the scope of the present invention. [Example]

[0127] The present invention will now be described with reference to examples and comparative examples, but the present invention is not limited thereto.

[0128] [Preparation of Conductive Paste] Varnishes 1-11 and A1-A7, which are incorporated into the conductive paste for spraying, were prepared by uniformly mixing the components according to the formulations shown in Tables 1 and 3. The content of each component in Tables 1 and 3 is expressed in parts by mass.

[0129] The details of the components shown in Tables 1 and 3 are as follows.

[0130] (Sintering accelerator) • Sintering accelerator 1: Polyethylene glycol diglycidyl ether (product name: EPOLITE400E, manufactured by KYOEISHA CHEMICAL Co., Ltd., equivalent to the aforementioned formula (1), m=9) • Sintering accelerator 2: Polyethylene glycol diglycidyl ether (product name: DENACOL EX-821, manufactured by Nagase ChemteX Corporation, equivalent to the aforementioned formula (1), m=4) • Sintering accelerator 3: Polypropylene glycol diglycidyl ether (product name: DENACOL EX-920, manufactured by Nagase ChemteX Corporation, equivalent to the aforementioned formula (2), n=3) • Sintering accelerator 4: Polypropylene glycol diglycidyl ether (product name: DENACOL EX-931, manufactured by Nagase ChemteX Corporation, equivalent to the aforementioned formula (2), n=11) • Sintering accelerator 5: Polyethylene glycol diglycidyl ether (product name: DENACOL EX-830, manufactured by Nagase ChemteX Corporation, equivalent to the aforementioned formula (1), n=9)

[0131] (Epoxy monomer) • Epoxy monomer 1: Trimethylolpropane polyoxypropylene ether (Product name: DENACOL EX-321L, manufactured by Nagase ChemteX Corporation) • Epoxy monomer 2: Bisphenol F type epoxy monomer (Product name: RE-303S, manufactured by Nippon Kayaku Co., Ltd.)

[0132] (Butadiene rubber containing epoxy groups) • Butadiene rubber containing epoxy groups 1: Epoxy-modified polybutadiene (Product name: NISSO-PB JP-200, manufactured by NIPPON SODA Co., Ltd.)

[0133] ((meth)acrylic acid monomer) • 1:1,4-Cyclohexanediethanol monoacrylate (product name: CHDMMA, manufactured by Nihon Kasei Co., Ltd.) • (Meth)acrylic acid monomer 2: Ethylene glycol dimethacrylate (Product name: Light Ester EG, manufactured by KYOEISHA CHEMICAL Co., Ltd.)

[0134] (hardener) • Hardener 1: Bisphenol F type phenolic resin (Product name: DIC-BPF, manufactured by DIC Corporation)

[0135] (Curing accelerator) • Hardening accelerator 1: 2-Phenyl-1H-imidazol-4,5-diethanol (Product name: 2PHZ-PW, manufactured by SHIKOKU CHEMICALS Corporation)

[0136] (Free radical polymerization initiator) • Free radical polymerization initiator 1: Diisopropylphenyl peroxide (Product name: Perkadox BC, manufactured by Kayaku Nouryon Corporation)

[0137] Next, a conductive paste was obtained by uniformly mixing the components according to the formulations shown in Tables 2 and 4. The content of each component in Tables 2 and 4 is expressed in parts by mass.

[0138] The details of the components shown in Tables 2 and 4 are as follows. (Contains silver particles) • Silver filler 1: Silver particles (Product name: AG-DSB-114, manufactured by DOWA Electronics Materials Co., Ltd., spherical, D 50: 0.7μm, specific surface area: 1.05m² / g, tap density: 5.25g / cm³, roundness: 0.953) • Silver filler 2: Silver particles (Product name: HKD-12, manufactured by FUKUDA METAL FOIL & POWDER Co., Ltd., flake-like, D 50: 7.6μm, specific surface area: 0.315m² / g, tap density: 5.5g / cm³) (solvent) Solvent 1: Tripropylene glycol mono-n-butyl ether (Product name: BFTG, manufactured by NIPPON NYUKAZAI Co., Ltd.)

[0139] [Preparation of hardened material] The obtained conductive paste was coated onto a glass plate, and the plate was heated from 30°C to 200°C over 60 minutes in a nitrogen atmosphere, followed by sintering at 200°C for 120 minutes. This yielded a hardened material with a thickness of 0.05 mm.

[0140] [Volume Resistivity] The volume resistivity of the hardened surface was measured using a DC four-electrode method based on a milliohm meter (HIOKI EE Corporation) with electrodes spaced 40 mm apart.

[0141] [Storage elasticity modulus] A short strip sample of approximately 0.1 mm × approximately 10 mm × approximately 4 mm was cut from the obtained hardened material. Using this short strip sample, the storage modulus of elasticity (E') at 25 °C was measured by DMA (Dynamic Viscoelasticity Measurement, Tensile Mode) at a heating rate of 5 °C / min and a frequency of 10 Hz.

[0142] [Table 1] Varnish 1 Varnish 2 varnish 3 4 varnish varnish 5 varnish 6 varnish 7 varnish 8 varnish 9 varnish 10 Varnish 11 Sintering accelerator Sintering accelerator 1 (parts by weight) 10 25 40 50 Sintering accelerator 2 (parts by weight) 25 50 Sintering accelerator 3 (parts by weight) 25 50 Sintering accelerator 4 (parts by weight) 25 50 Epoxy monomers Epoxy Monomer 1 (parts by weight) 40 25 10 25 25 25 Epoxy monomer 2 (parts by weight) 50 (meth)acrylic acid monomer (Meth)acrylic acid monomer 1 (parts by weight) 20 20 20 20 20 20 20 20 20 20 (Meth)acrylic acid monomer 2 (parts by weight) 20 hardener Hardener 1 (parts by weight) 20 20 20 20 20 20 20 20 20 20 20 hardening accelerator Hardening accelerator 1 (parts by weight) 1 1 1 1 1 1 1 1 1 1 1 free radical polymerization initiators Free radical polymerization initiator 1 (parts by weight) 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2

[0143] [Table 2] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative Example 1 varnish Varnish 1 (parts by weight) 10.0 Varnish 2 (parts by weight) 10.0 varnish 3 (parts by weight) 10.0 4 varnish (parts by weight) 10.0 varnish 5 (parts by weight) 10.0 varnish 6 (parts by weight) 10.0 varnish 7 (parts by weight) 10.0 varnish 8 (parts by weight) 10.0 varnish 9 (parts by weight) 10.0 varnish 10 (parts by weight) 10.0 Varnish 11 (parts by weight) 10.6 Silver particles Silver filler 1 (parts by weight) 55.0 55.0 55.0 55.0 55.0 55.0 55.0 55.0 55.0 55.0 45.0 Silver filler 2 (parts by weight) 31.0 31.0 31.0 31.0 31.0 31.0 31.0 31.0 31.0 31.0 40.0 solvent Solvent 1 (parts by weight) 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.4 Volume resistivity (μΩ·cm) 7.4 6.9 4.5 4.6 5.9 5.4 8.9 9.2 7.6 5.1 10.8 Storage elasticity modulus (E´) (GPa) 9.0 8.6 14.0 10.6 7.4 7.9 11.2 6.5 7.4 5.0 20.0

[0144] [Table 3] Varnish A1 Varnish A2 Clear varnish A3 Clear varnish A4 Clear varnish A5 Clear varnish A6 Clear varnish A7 Sintering accelerator Sintering accelerator 5 (parts by weight) 25 50 twenty three 61 61 42 30 Epoxy monomers Epoxy Monomer 1 (parts by weight) 25 twenty three Butadiene rubber containing epoxy groups Butadiene rubber containing epoxy groups 1 (parts by weight) 18 30 (meth)acrylic acid monomer (Meth)acrylic acid monomer 1 (parts by weight) 20 20 20 10 10 10 10 hardener Hardener 1 (parts by weight) 20 20 twenty four 19 19 20 20 hardening accelerator Hardening accelerator 1 (parts by weight) 1.0 1.0 1.0 1.1 1.1 1.1 1.1 free radical polymerization initiators Free radical polymerization initiator 1 (parts by weight) 1.2 1.2 1.2 0.6 0.6 0.6 0.6

[0145] [Table 4] Example A1 Example A2 Example A3 Example A4 Example A5 Example A6 Example A7 Comparative Example 1 varnish Varnish A1 (parts by weight) 10.0 Varnish A2 (parts by weight) 10.0 Clear varnish A3 (parts by weight) 7.0 Clear varnish A4 (parts by weight) 7.0 Clear varnish A5 (parts by weight) 6.0 Clear varnish A6 (parts by weight) 7.0 Clear varnish A7 (parts by weight) 7.0 Varnish 11 (parts by weight) 10.6 Silver particles Silver particles 1 (parts by weight) 55.0 55.0 47.0 47.0 47.5 47.0 47.0 45.0 Silver particles 2 (parts by weight) 31.0 31.0 42.0 42.0 42.5 42.0 42.0 40.0 solvent Solvent 1 (parts by weight) 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.4 Volume resistivity (μΩ·cm) 9.8 6.6 5.7 4.8 4.6 4.8 4.9 10.8 Storage elasticity modulus (E´) (GPa) 9.0 10.7 12.5 13.3 14.2 10.6 9.6 20.0

[0146] As shown in Tables 2 and 4 above, it was confirmed that the conductive pastes of each embodiment have lower volume resistivity and better conductivity compared to the conductive pastes of the comparative examples.

[0147] [SEM observation of the hardened cross-section] A section measuring approximately 4 mm × 10 mm × 50 μm was cut from the hardened material for SEM observation. The SEM section was observed using a scanning electron microscope (Miniscope™ 3030, manufactured by Hitachi High-Technologies Corporation) at a magnification of 5000x.

[0148] The SEM image of Example 2 is shown in Figure 2, and the SEM image of Comparative Example 1 is shown in Figure 3. In each SEM image, the white portion represents silver-containing particles. In the SEM image of Example 2, it can be seen that compared with the SEM image of Comparative Example 1, more silver-containing particles fused together, and sintering was promoted.

[0149] This application claims priority based on Japanese Application No. 2021-155956 filed on September 24, 2021 and Japanese Application No. 2022-141719 filed on September 6, 2022, and the entire contents disclosed herein are incorporated herein by reference.

[0150] 10: Next layer 20: Semiconductor components 30:Substrate 40: Joint line 50: Molding resin 60: Welding ball 100: Semiconductor devices

Claims

1. A conductive paste comprising: silver particles; and a sintering accelerator that promotes the sintering of the silver particles together, wherein the sintering accelerator comprises a compound represented by formula (1) or formula (2), wherein the conductive paste further comprises a (meth)acrylic acid monomer, wherein when the conductive paste is set to 100 parts by mass, the content of the sintering accelerator is 0.5 parts by mass or more and 50 parts by mass or when the conductive paste is set to 100 parts by mass, the content of the (meth)acrylic acid monomer is 0.3 parts by mass or more and 50 parts by mass or when the conductive paste is set to 100 parts by mass, wherein in formula (1), m is an integer of 1 or more and 20 or less, and in formula (2), n is an integer of 1 or more and 20 or less.

2. As in the conductive paste of request item 1, wherein, The aforementioned sintering accelerator includes the compound represented by formula (1), where m is an integer greater than or equal to 1 and less than or equal to 11.

3. The conductive paste as requested in item 1 or 2, wherein, The aforementioned sintering accelerator includes the compound represented by formula (2), where n is an integer greater than 2 and less than 13.

4. The conductive paste as requested in item 1 or 2, wherein, The aforementioned silver-containing particles include one or more types selected from the group consisting of spherical particles, scale-like particles, condensed particles, and polyhedral-shaped particles.

5. As in request item 4, the conductive paste, wherein, The aforementioned silver-containing particles include two or more types selected from the group consisting of spherical particles, scale-like particles, condensed particles, and polyhedral-shaped particles.

6. The conductive paste of claim 1 or 2 further comprises an epoxy monomer.

7. The conductive paste of claim 6 further comprises a phenolic curing agent.

8. The conductive paste of claim 6 further comprises an imidazole curing accelerator.

9. The conductive paste of claim 1 or 2 further comprises a free radical polymerization initiator.

10. The conductive paste of claim 1 or 2 further comprises a solvent.

11. The conductive paste as requested in item 1 or 2, wherein, When a conductive paste is applied to a glass plate to a thickness of 0.05 mm after sintering, and the plate is heated from 30°C to 200°C for 60 minutes in a nitrogen environment, and then sintered at 200°C for 120 minutes to obtain a hardened material, the volume resistivity of the hardened material is 4.0 μΩ·cm or more and 9.5 μΩ·cm or less.

12. A hardened material obtained by sintering the conductive paste of any one of claims 1 to 11.

13. A sintering accelerator that promotes the sintering of silver-containing particles together, comprising a compound represented by formula (1) or formula (2), wherein the aforementioned sintering accelerator is used in a conductive paste containing silver-containing particles and (meth)acrylic acid monomer, wherein when the aforementioned conductive paste is set to 100 parts by mass, the content of the aforementioned sintering accelerator is 0.5 parts by mass or more and 50 parts by mass or when the aforementioned conductive paste is set to 100 parts by mass, the content of the aforementioned (meth)acrylic acid monomer is 0.3 parts by mass or more and 50 parts by mass or when the aforementioned conductive paste is set to 100 parts by mass, wherein in formula (1), m is an integer of 1 or more and 20 or less, and in formula (2), n is an integer of 1 or more and 20 or less.

14. A sintering promotion method, wherein the sintering accelerator of claim 13 is used to promote the sintering of silver-containing particles.

Images