Connection structure, metal atom-containing particles and bonding composition

Abstract

A connection structure in which the occurrence of warping and cracking is suppressed even when stress is applied to the connection structure, and metal atom-containing particles and a bonding composition used for assembling the connection structure are provided. [Solution] A connection structure A includes a metal atom-containing particle 10 and an adhesive layer 50 including a sintered body 20 of metal particles. The metal atom-containing particle 10 and the sintered body 20 are in contact with each other through a chemical bond, and in the cross section of the adhesive layer 50, 5% or more of the outer periphery of the metal atom-containing particle 10 is in contact with the sintered body.

Description

[Technical Field]

[0001] The present invention relates to a connection structure, metal atom-containing particles used to form the connection structure, and a bonding composition. [Background technology]

[0002] It has been known that a connecting member is used to fix a semiconductor element in a non-insulated semiconductor device, which is one type of power semiconductor device used in an inverter or the like. Such a connecting member can also serve as one of the electrodes of the semiconductor device. For example, in a semiconductor device in which a power transistor is mounted on a connecting member using a Sn-Pb soldering material, the connecting member (base material) connecting two components to be connected serves as the collector electrode of the power transistor.

[0003] In recent years, there has been a demand for further improvements in the performance of connection structures such as semiconductor devices, including those described above, such as heat resistance, thermal conductivity, and volume resistance. Therefore, various methods for assembling connection structures such as semiconductor devices using materials other than the above-mentioned soldering materials have been investigated. One example is a method for assembling connection structures using a material containing a metal with a small particle size as a connection material (see, for example, Patent Document 1). This connection material utilizes the property of metal particles: when the particle size of the metal particles is reduced to 100 nm or less and the number of constituent atoms decreases, the surface area-to-volume ratio of the particles increases rapidly, resulting in a significant decrease in the melting point or sintering temperature compared to the bulk state. For example, metal particles with an average particle size of 100 nm or less whose surfaces are coated with an organic substance are used as a connection material. Heating the organic substance decomposes the metal particles, sintering them together, forming an adhesive layer, which connects two components to be connected. This connection method converts the metal particles into bulk metal after connection, while simultaneously achieving a metallic bond at the connection interface, thereby improving the heat resistance, connection reliability, and heat dissipation of the connection structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-55046 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in connection structures such as semiconductor devices, the adhesive layer connecting two connection target components is exposed to thermal cycling conditions, which applies stress to the connection target components, such as semiconductor wafers and semiconductor chips, making them prone to warping and cracking. For example, when a semiconductor device is operating, a current of several amperes or more flows through the collector electrode, causing the transistor chip to heat up and generate thermal stress, which can lead to warping of the semiconductor chip. While various connection materials for assembling connection structures have been proposed, including those disclosed in Patent Document 1, no attempt has been made to improve the connection materials in order to prevent warping and cracking caused by stress. Therefore, there is currently a demand for the construction of a high-performance connection structure that is more durable and suppresses warping and cracking even when stress is applied to the connection structure.

[0006] The present invention has been made in consideration of the above, and aims to provide a connection structure that suppresses the occurrence of warping and cracks even when stress is applied to the connection structure, as well as metal atom-containing particles and a bonding composition used to assemble this connection structure. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to achieve the above object, and have concluded that in order to prevent warping and cracking in a connection structure, it is important to relieve the stress on the adhesive layer connecting two connection structures of the connection structure. As a result of further extensive research, they have found that the above object can be achieved by incorporating particles having a stress-relieving effect into the adhesive layer and increasing the contact area between the surface of these particles and the sintered body constituting the adhesive layer compared to conventional methods, and have thus completed the present invention.

[0008] That is, the present invention includes, for example, the subject matter described in the following sections. Item 1. A connection structure having an adhesive layer containing metal atom-containing particles and a sintered body of metal particles, the metal atom-containing particles and the sintered body are in contact with each other via a chemical bond, A bonded structure in which 5% or more of the circumferential length of the metal atom-containing particle is in contact with the sintered body in a cross section of the adhesive layer. Item 2. The connection structure according to Item 1, wherein the metal atom-containing particle comprises a base particle and a metal portion disposed on the surface of the base particle. Item 3. The connection structure according to claim 2, wherein the metal part has a plurality of protrusions on its outer surface. Item 4. The connection structure according to Item 3, wherein the average diameter of the base of the projections is 3 nm or more and 5000 nm or less. Item 5. The connection structure according to Item 3 or 4, wherein the average height of the protrusions is 1 nm or more and 1000 nm or less. Item 6. The connection structure according to any one of Items 3 to 5, wherein the protrusions occupy 30% or more of the total surface area (100%) of the outer surface of the metal part. Item 7. The connection structure according to any one of Items 2 to 6, wherein the total amount of nickel, chromium, platinum, and rhodium in the metal portion is 30 mass % or less with respect to the total mass of the metal portion. Item 8. The connection structure according to any one of Items 2 to 7, wherein the metal portion includes one or more elements selected from the group consisting of gold, silver, tin, copper, germanium, indium, palladium, tellurium, thallium, bismuth, zinc, arsenic, selenium, and alloys containing at least one of these metal elements. Item 9. The connection structure according to any one of Items 2 to 8, wherein a plurality of recesses are formed on the surface of the base particle. Item 10. Metal atom-containing particles for use in the connection structure according to any one of Items 1 to 9. Item 11. A bonding composition comprising the metal atom-containing particles according to item 10 and metal particles. [Effects of the Invention]

[0009] The connection structure according to the present invention is excellent in durability because it is less likely to warp or crack even when stress is applied to the connection structure, and therefore it is possible to provide, for example, a power device that is highly reliable and has excellent performance.

[0010] The metal atom-containing particles according to the present invention are suitable as a material for assembling the above-mentioned connection structure, and can provide a connection structure that is less susceptible to warping and cracking. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of an example of a connection structure according to an embodiment of the present invention; [Figure 2] 1A and 1B are schematic diagrams showing an example of the structure of a metal atom-containing particle, illustrating its appearance and partial cross-sectional structure. [Figure 3] 3A and 3B are schematic diagrams showing the appearance and partial cross-sectional structure of another example of the structure of a metal atom-containing particle. [Figure 4] 3A and 3B are schematic diagrams showing the appearance and partial cross-sectional structure of another example of the structure of a metal atom-containing particle. [Figure 5] 3A and 3B are schematic diagrams showing the appearance and partial cross-sectional structure of another example of the structure of a metal atom-containing particle. [Figure 6] 1A is a schematic diagram of the cross-sectional structure of an adhesive layer in the connection structure of this embodiment, and FIG. 1B is a schematic diagram of the cross-sectional structure of an adhesive layer in a conventional connection structure. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0023] In the present specification, the terms "contain" and "comprise" include the concepts of "contain," "comprise," "consist essentially of," and "consist only of."

[0013] FIG. 1 shows an example of a connection structure according to this embodiment, and schematically shows the cross-sectional structure of the connection structure.

[0014] The connection structure of this embodiment comprises an adhesive layer containing metal atom-containing particles and a sintered body of metal particles, the metal atom-containing particles and the sintered body being in contact with each other via a chemical bond, and in the cross section of the adhesive layer, 5% or more of the circumferential length of the metal atom-containing particles is in contact with the sintered body.

[0015] In the connection structure of this embodiment, the contact area of ​​the metal atom-containing particles with the sintered body of the metal particles is large, so that even if stress is applied to the connection structure, the connection structure is less likely to warp or crack, thereby providing the connection structure with excellent durability.

[0016] 1 includes a first connection target member 51, a second connection target member 52, and an adhesive layer 50 connecting the first and second connection target members. The first connection target member 51 and the second connection target member 52 are connected by the adhesive layer 50.

[0017] The adhesive layer 50 is formed to include metal atom-containing particles 10 and a sintered body 20 of metal particles. As in the connection structure A of this embodiment, the adhesive layer 50 can also include gap control particles 30. The particle diameter of the gap control particles 30 is the same as the thickness of the adhesive layer 50, and they can function as spacers between the first member to be connected 51 and the second member to be connected 52, so to speak. The gap control particles 30 can be, for example, known conductive particles, but are not limited to this.

[0018] Specific examples of the connection target members 51 and 52 include, but are not limited to, electronic components such as semiconductor chips, capacitors, and diodes, as well as circuit boards such as printed circuit boards, flexible printed circuit boards, glass epoxy boards, and glass boards. The connection target members 51 and 52 are preferably electronic components.

[0019] At least one of the first connection target member 51 and the second connection target member 52 is preferably a semiconductor wafer or a semiconductor chip. In other words, the connection structure A is preferably a semiconductor device.

[0020] The following provides a detailed description of the configurations of the metal atom-containing particles 10 and the sintered body 20 of metal particles contained in the adhesive layer 50. In the following description, the reference numerals in FIG. 1 may be omitted.

[0021] There are no particular limitations on the type of metal atom-containing particles, as long as they are capable of forming chemical bonds with the sintered body of metal particles.

[0022] For example, the metal atom-containing particle preferably comprises a base particle and a metal portion disposed on the surface of the base particle. In this case, the metal atom-containing particle is likely to form a chemical bond, particularly a metallic bond, with the sintered body of the metal particle. More specifically, the metal portion on the surface of the metal atom-containing particle and the sintered body of the metal particle can form a so-called solid solution, which further strengthens the bond between the metal atom-containing particle and the sintered body, making it easier to suppress the occurrence of warping and cracks in the connection structure.

[0023] The type of the base particle is not particularly limited, and examples thereof include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles. The base particle is preferably a resin particle, an inorganic particle other than metal particles, or an organic-inorganic hybrid particle.

[0024] When base material particle is resin particle, various organic substances can be suitably used as the material for forming resin particle.Such material can be enumerated as polyethylene, polypropylene, polystyrene, silicone resin, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, polybutadiene and other polyolefin resins; polymethyl methacrylate, polymethyl acrylate and other acrylic resins; polyalkylene terephthalate, polysulfone, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, epoxy resin, saturated polyester resin, unsaturated polyester resin, polyphenylene oxide, polyacetal, polyimide, polyamideimide, polyetheretherketone, polyethersulfone, urea resin and the like.

[0025] Resin particles can also be obtained by polymerizing one or more of various polymerizable monomers having ethylenically unsaturated groups. In this case, it is possible to design and synthesize resin particles having any physical properties during compression suitable for anisotropic conductive materials. In addition, in this case, the hardness of the base particle can be easily controlled within a suitable range. From this perspective, the material of the resin particles is preferably a polymer obtained by polymerizing one or more polymerizable monomers having multiple ethylenically unsaturated groups.

[0026] When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer and / or a crosslinkable monomer. In the following description, "(meth)acrylic" means one or both of "acrylic" and "methacrylic", and "(meth)acrylate" means one or both of "acrylate" and "methacrylate".

[0027] Examples of the non-crosslinkable monomer include vinyl compounds such as styrene-based monomers, α-methylstyrene, and chlorostyrene; vinyl ethers, such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, and diethylene glycol divinyl ether; acid vinyl esters, such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; halogen-containing monomers, such as vinyl chloride and vinyl fluoride; (meth)acrylic compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; Examples of suitable α-olefin compounds include alkyl (meth)acrylates such as cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; oxygen-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate; nitrile-containing monomers such as (meth)acrylonitrile; halogen-containing (meth)acrylates such as trifluoromethyl (meth)acrylate and pentafluoroethyl (meth)acrylate; α-olefin compounds include olefins such as diisobutylene, isobutylene, linalene, ethylene, and propylene; and conjugated diene compounds such as isoprene and butadiene.

[0028] Examples of the crosslinkable monomer include vinyl compounds such as vinyl monomers like divinylbenzene, 1,4-divinyloxybutane, and divinylsulfone; (meth)acrylic compounds such as polyfunctional (meth)acrylates like tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; and allyl compounds such as triallyl(iso)cyanuric acid. acrylate, triallyl trimellitate, diallyl phthalate, diallyl acrylamide, diallyl ether; silicone compounds, such as silane alkoxides as tetramethoxysilane, tetraethoxysilane, triethylsilane, t-butyldimethylsilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, cyclohexyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, trimethoxysilylstyrene, γ-(meth)acryloxypropyltrimethoxysilane, 1,3-divinyltetramethyldisiloxane, methylphenyldimethoxysilane, and diphenyldimethoxysilane;Examples of suitable silane alkoxides include polymerizable double bonds such as vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxydimethylvinylsilane, dimethoxyethylvinylsilane, diethoxymethyldivinylsilane, diethoxyethylvinylsilane, ethylmethyldivinylsilane, methylvinyldimethoxysilane, ethylvinyldimethoxysilane, methylvinyldiethoxysilane, ethylvinyldiethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane; cyclic siloxanes such as decamethylcyclopentasiloxane; modified (reactive) silicone oils such as single-end modified silicone oil, double-end silicone oil, and side-chain silicone oil; and carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride.

[0029] The crosslinkable and non-crosslinkable monomers are not limited to the monomers exemplified above, but may be other polymerizable monomers, for example, known polymerizable monomers.

[0030] The resin particles can be obtained by polymerizing the polymerizable monomer having the ethylenically unsaturated group by a known method. Examples of such methods include suspension polymerization in the presence of a radical polymerization initiator, and a method in which non-crosslinked seed particles are used to swell and polymerize the monomer together with a radical polymerization initiator (so-called seed polymerization method). The conditions for these polymerization methods are not particularly limited, and known conditions can be widely applied.

[0031] 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 and carbon black. Preferably, 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, and then optionally baking the particles. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

[0032] Another example of the material for the base particle is a resin containing polyrotaxane. Polyrotaxane refers to a structure in which a chain polymer penetrates the opening of a cyclic molecule. The type of polyrotaxane is not particularly limited, and examples thereof include known polyrotaxanes.

[0033] When the material constituting the base particle is a resin containing polyrotaxane, the polyrotaxane is preferably a crosslinked material. Specifically, it is preferable that the polyrotaxane has a structure in which cyclic molecules in one polyrotaxane and cyclic molecules in another polyrotaxane are crosslinked by a polymer chain. As long as the polyrotaxane is of this type, the flexibility of the base particle is increased, and the stress relaxation effect is easily exerted, which makes it easier to suppress the occurrence of cracks and warpage in the connection structure. The type of such a crosslinked polyrotaxane is not particularly limited, and examples thereof include known crosslinked polyrotaxanes.

[0034] The polyrotaxane can be produced by, for example, a known method. For example, a polyrotaxane having a crosslinked structure can be produced by reacting a polyrotaxane having cyclic molecules with a polymerizable functional group with a mixture of a polymerizable monomer. This reaction can be carried out by, for example, a known method.

[0035] There are no particular limitations on the type of polyrotaxane comprising cyclic molecules with polymerizable functional groups. Specific examples include "Cellum® Super Polymer SM3405P," "Cellum® Key Mixture SM3400C," "Cellum® Super Polymer SA3405P," "Cellum® Super Polymer SA2405P," "Cellum® Key Mixture SA3400C," "Cellum® Key Mixture SA2400C," "Cellum® Super Polymer SA3405P," and "Cellum® Super Polymer SA2405P," all of which are commercially available from Advanced Soft Materials, Inc.

[0036] The average particle size of the base particles is not particularly limited, but can be, for example, less than half the thickness of the adhesive layer in the connection structure. When the average particle size of the base particles is within the above range, cracks and warping of the adhesive layer are unlikely to occur, and the adhesive strength of the adhesive layer is also unlikely to decrease.

[0037] It is also preferable that the average particle size of the base particles is 0.1 μm or more and 55 μm or less. In this case, cracks and warping of the connection structure are unlikely to occur during thermal cycling, and the adhesive strength of the adhesive layer is unlikely to decrease after thermal cycling tests. The average particle size of the base particles is preferably 0.5 μm or more, more preferably 1 μm or more, and is preferably 40 μm or less, more preferably 10 μm or less, and particularly preferably 6 μm or less.

[0038] The average particle diameter of the base particles can be the same as the thickness of the adhesive layer, in which case the metal atom-containing particles can also serve as the gap control particles 30 described with reference to FIG.

[0039] The average particle diameter of the base particles referred to above means the diameter when the shape is spherical, and means the average of the maximum and minimum diameters when the shape is other than spherical. The average particle diameter of the base particles refers to the average value obtained by observing the base particles with a scanning electron microscope and measuring the particle diameters of 50 randomly selected base particles with a vernier caliper. Note that when the base particles are coated with another material (e.g., a metal part) as described above, the average particle diameter also includes the coating layer.

[0040] The coefficient of variation (CV value) of the particle diameter of the base particles is, for example, 50% or less. The coefficient of variation (CV value) is expressed by the following formula. CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of particle size Dn: average particle size of particles From the viewpoint of further suppressing the occurrence of cracks or peeling in the connection structure, the CV value of the particle diameter of the base particle is preferably 40% or less, more preferably 30% or less. There is no particular limitation on the lower limit of the CV value of the particle diameter of the base particle. The CV value may be 0% or more, 5% or more, 7% or more, or 10% or more.

[0041] The hardness of the base particles is not particularly limited, and may be, for example, 10 N / mm 2 More than 3000N / mm 2 From the viewpoint of further suppressing the occurrence of cracks and warpage in the connection structure, the 10% K value is preferably 100 N / mm 2 More preferably, 1000N / mm 2 More than 2500N / mm 2 Below 2000N / mm, particularly preferably 2 The following is the result.

[0042] The 10% K value referred to here is the compressive modulus when the base particle is compressed by 10%. It can be measured as follows. First, using a microcompression tester, the base particle is compressed with the smooth end face of a cylindrical indenter (diameter 50 μm, made of diamond) under conditions of 25°C and a maximum test load of 20 mN for 60 seconds. The load value (N) and compression displacement (mm) at this time are measured. From the obtained measured values, the above-mentioned compressive modulus can be calculated using the following formula. 10% K value (N / mm 2 )=(3 / 2 1 / 2 )·F·S -3 / 2 ·R -1 / 2 F: Load value (N) when the particle is compressed by 10% S: Compression displacement (mm) when the particle is compressed by 10% R: particle radius (mm) As the microcompression tester, for example, the "Fisherscope H-100" manufactured by Fischer Co., Ltd. can be used. The 30% K value can also be calculated by determining each of the above parameters when the particles are compressed and deformed by 30%.

[0043] The base particles preferably have 100 or fewer agglomerated particles per 1 million particles. The agglomerated particles are particles in which one particle is in contact with at least one other particle. For example, if 1 million base particles contain three particles each consisting of an agglomeration of three particles (agglomerates of three particles), the number of agglomerated particles per 1 million base particles is 9. Examples of methods for measuring the agglomerated particles include counting the agglomerated particles using a microscope set to a magnification such that approximately 50,000 particles can be observed in one field of view, and measuring the agglomerated particles as a total of 20 fields of view.

[0044] The base particles preferably have a thermal decomposition temperature of 200°C or higher. In this case, thermal decomposition of the base particles is likely to be suppressed when an adhesive layer of the connection structure is formed, as described below. The thermal decomposition temperature of the base particles is preferably 220°C or higher, more preferably 250°C or higher, and even more preferably 300°C or higher. In addition, when the base particles have a coating layer described below, the temperature at which the base particles or the coating layer are thermally decomposed first is defined as the thermal decomposition temperature of the base particles.

[0045] The metal portion may be disposed on the surface of the base particle, for example, the metal portion may be present so as to cover the surface of the base particle.

[0046] The metal portion is formed from a material containing a metal. Examples of the metal include gold, silver, tin, copper, germanium, indium, palladium, tellurium, thallium, bismuth, zinc, arsenic, selenium, iron, lead, ruthenium, aluminum, cobalt, titanium, antimony, cadmium, silicon, nickel, chromium, platinum, and rhodium. The metal portion may contain only one of these metals, or two or more of them. The metal portion may also be an alloy of two or more of the metals listed above. The metal content of the metal portion is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 99% by mass or more, based on the total mass of the metal portion. The metal portion may also be formed solely from metal.

[0047] In the metal portion, the total amount of nickel, chromium, platinum, and rhodium is preferably 30 mass % or less relative to the total mass of the metal portion.

[0048] When the total amount of the nickel, chromium, platinum, and rhodium is within the above range relative to the total mass of the metal portion, the sintered body, particularly when the particles constituting the sintered body are silver, is more susceptible to metal diffusion, and as a result, the metal atom-containing particles are more likely to come into contact with the sintered body.

[0049] The total amount of nickel, chromium, platinum, and rhodium is preferably 25 mass% or less, more preferably 20 mass% or less, even more preferably 10 mass% or less, and particularly preferably 0 mass% relative to the total mass of the metal portion. When the total amount of nickel, chromium, platinum, and rhodium in the metal portion is within the above ranges relative to the total mass of the metal portion, the metal atom-containing particles are particularly likely to come into contact with the sintered body.

[0050] The metal portion preferably contains one or more selected from the group consisting of gold, silver, tin, copper, germanium, indium, palladium, tellurium, thallium, bismuth, zinc, arsenic, selenium, and alloys containing at least one of these metal elements. In this case, the metal atom-containing particles and the sintered body of the metal particles are more likely to come into contact with each other, further suppressing warping and cracking of the connection structure.

[0051] A particularly preferred metal portion contains a metal with a thermal conductivity of 200 W / m·K or higher. When such a metal is contained, warping and cracking of the connection structure are more likely to be suppressed, and heat dissipation can also be improved. Examples of such metals include one selected from the group consisting of gold, silver, and copper.

[0052] The metal portion may be formed of one layer, or may be formed of multiple layers.

[0053] The metal portion preferably has a multi-layer structure, which is formed from a plurality of layers. Each layer may contain a different metal. For example, the metal portion may have a two-layer structure.

[0054] Figure 2 shows a schematic view of the appearance of a metal atom-containing particle having a metal portion formed in a two-layer structure. In order to show a partial cross-sectional structure of the metal atom-containing particle, the portion surrounded by the dashed line in Figure 2 is broken away.

[0055] The metal atom-containing particle 10 in the form shown in Fig. 2 comprises a base particle 11 and a metal portion 12. The metal portion 12 is arranged so as to cover the surface of the base particle 11. The metal portion 12 has a two-layer structure of a first metal portion 12a and a second metal portion 12b, with the first metal portion 12a arranged on the inside and the second metal portion 12b arranged on the outside. In other words, the first metal portion 12a is in contact with the surface of the base particle 11, and the second metal portion 12b is present so as to cover the surface of the first metal portion 12a.

[0056] When the metal atom-containing particle 10 has a two-layer metal portion as shown in FIG. 2, it is particularly preferable that the first metal portion 12a and the second metal portion 12b contain one or more metals selected from the group consisting of gold, silver, and copper. Specifically, the first metal portion 12a contains copper, and the second metal portion 12b contains silver. When the second metal portion 12b is made of silver, the contact area with the metal sintered compact tends to be larger, making it easier to contact the metal sintered compact. Furthermore, if the first metal portion 12a is made of copper, the amount of silver used in the second metal portion 12b can be reduced, which is economically advantageous.

[0057] In the metal atom-containing particles used in the connection structure of this embodiment, the thickness of the metal portion is preferably 0.5 nm or more, more preferably 10 nm or more, and preferably 10 μm or less, more preferably 1 μm or less, even more preferably 500 nm or less, and particularly preferably 300 nm or less. When the thickness of the metal portion is above the above lower limit and below the above upper limit, the metal atom-containing particles are more easily dispersed in the sintered body of metal particles and are more easily in contact with the sintered body (i.e., the contact area of ​​the metal atom-containing particles with the sintered body is increased), thereby further suppressing the occurrence of warping and cracking in the connection structure. When the metal portion is multilayered, the thickness of the metal portion refers to the sum of the thicknesses of each layer, i.e., the thickness of the entire metal portion.

[0058] In the metal atom-containing particles used in the connection structure of this embodiment, the method for forming the metal portion on the surface of the base particle is not particularly limited. Examples of methods for forming the metal portion include electroless plating, electroplating, physical vapor deposition, and coating the surface of the base particle with a metal powder or a paste containing a metal powder and a binder. From the viewpoint of ease of forming the metal portion, electroless plating is preferred. Examples of physical vapor deposition methods include vacuum deposition, ion plating, and ion sputtering.

[0059] The metal part can also be formed in a multilayer structure by a similar method. For example, by employing the above-described metal part formation method, a first layer of metal part is formed on the surface of the base particle, and then subsequent layers are successively formed on the surface of this first layer, thereby forming a multilayer metal part.

[0060] The above-described form of the metal portion is merely an example, and the metal atom-containing particle may have a metal portion in a form other than the above.

[0061] The metal part may have a plurality of protrusions on its outer surface.

[0062] Fig. 3 is a schematic diagram showing the appearance of a metal atom-containing particle having a metal portion with a plurality of protrusions on the outer surface thereof. In order to show a partial cross-sectional structure of the metal atom-containing particle, the portion surrounded by the dashed line in Fig. 3 is broken away.

[0063] The metal atom-containing particle 10 in the form of FIG. 3 comprises a base particle 11 and a metal portion 12. The metal portion 12 is arranged so as to cover the surface of the base particle 11. The metal portion 12 is formed into a two-layer structure of a first metal portion 12a and a second metal portion 12b, with the first metal portion 12a arranged on the inside and the second metal portion 12b arranged on the outside. In other words, the first metal portion 12a is in contact with the surface of the base particle 11, and the second metal portion 12b is present so as to cover the surface of the first metal portion 12a. The configuration of the metal portion 12 formed into a two-layer structure can be the same as the configuration of the metal atom-containing particle 10 in the form of FIG. 2 described above.

[0064] A plurality of protrusions 13 are formed on the outer surface of the metal part 12. The protrusions 13 are formed so as to protrude from a base portion as the bottom surface toward the surface side. The presence of such a plurality of protrusions 13 facilitates contact between the metal atom-containing particles and the sintered body of metal particles, which in turn helps to suppress the occurrence of warping and cracks in the connection structure. The base portion is formed on the surface of the metal part 12.

[0065] The method for forming the protrusions is not particularly limited, and can employ known methods, for example.Specifically, the method of attaching a core material to the surface of a base particle, and then forming a metal part by electroless plating, and the method of forming a metal part on the surface of a base particle by electroless plating, and then attaching a core material, and then forming a metal part by electroless plating, etc. can be mentioned.Furthermore, other methods for forming the protrusions include the method of forming a first metal part on the surface of a base particle, then disposing a core material on the first metal part, and then forming a second metal part, and the method of adding a core material during the process of forming a metal part on the surface of a base particle, etc.

[0066] The method of adhering the core substance to the surface of the base particle can be exemplified by adding the core substance to the dispersion of the base particle, and accumulating and adhering the core substance to the surface of the base particle by, for example, van der Waals force, and adding the core substance to a container containing the base particle, and adhering the core substance to the surface of the base particle by mechanical action such as rotating the container.Among these, from the viewpoint of easily controlling the amount of the core substance to be adhered, the method of adhering and adhering the core substance to the surface of the base particle in the dispersion is preferred.If the core substance is embedded in the metal part, it is possible to easily form protrusions on the outer surface of the metal part.

[0067] Examples of materials for the core substance include conductive and non-conductive substances. Examples of conductive substances include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of conductive polymers include polyacetylene. Examples of non-conductive substances include silica, alumina, and zirconia. Metals are preferred because they are more likely to come into contact with the sintered body. The core substance is preferably a metal particle. Examples of metals in this case include the various metals mentioned above that can form the metal part. It is more preferable that the metal be the same as the type of metal that forms the outermost layer of the metal part. Therefore, it is particularly preferable that the metal that forms the protrusions includes one or more selected from the group consisting of gold, silver, and copper.

[0068] 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.

[0069] The average diameter (average particle diameter) 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. The average diameter (average particle diameter) of the core material refers to the number-average diameter (number-average particle diameter). The average diameter of the core material is determined by observing 50 random core materials using an electron microscope or optical microscope and calculating the average value. When measuring the average diameter of the core material of metal-atom-containing particles, for example, the average diameter of the core material can be measured as follows. The metal-atom-containing particles are added to "Technovit 4000" manufactured by Kulzer so as to have a content of 30 wt% and dispersed to prepare an embedding resin for metal-atom-containing particle inspection. A cross section of the metal-atom-containing particle is cut out using an ion milling device ("IM4000" manufactured by Hitachi High-Technologies Corporation) so as to pass through the vicinity of the center of the metal-atom-containing particles dispersed in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM) set to an image magnification of 50,000 times, 20 metal atom-containing particles are randomly selected, and 20 protrusions of each metal atom-containing particle are observed. The diameters of the core substances in the obtained metal atom-containing particles are measured, and the arithmetic mean is taken as the average diameter of the core substances.

[0070] The shape of the protrusions is not particularly limited, and may be, for example, formed so that the cross section is spherical or elliptical, or may be formed in a needle shape that becomes sharper toward the tip. The shape of such protrusions can be controlled, for example, depending on the material of the core substance.

[0071] The average height of the protrusions can be 1 nm or more and 1000 nm or less, preferably 5 nm or more, more preferably 50 nm or more, and preferably 900 nm or less, more preferably 500 nm or less. When the average height of the protrusions is equal to or more than the above lower limit and equal to or less than the above upper limit, the metal atom-containing particles are more likely to come into contact with the sintered body.

[0072] The average height of the protrusions can be measured, for example, as follows. Metal-atom-containing particles are added to Kulzer's Technovit 4000 so that the content is 30% by weight, and dispersed to prepare a metal-atom-containing particle testing embedding resin. An ion milling device (Hitachi High-Technologies Corporation's IM4000) is used to cut out a cross section of the metal-atom-containing particles so that it passes through the center of the dispersed metal-atom-containing particles in the testing embedding resin. Then, using a field-emission scanning electron microscope (FE-SEM) set to an image magnification of 50,000 times, 20 metal-atom-containing particles are randomly selected, and 50 protrusions of each metal-atom-containing particle are observed. The height from the base (bottom surface) of the protrusion to the top of the protrusion is defined as the protrusion height, and the arithmetic mean is taken to determine the average height of the protrusions.

[0073] The average diameter of the base of the protrusions can be 3 nm or more and 5000 nm or less, preferably 50 nm or more, more preferably 80 nm or more, preferably 1000 nm or less, more preferably 500 nm or less. The average diameter of the base here refers to a value obtained by observing the protrusions of 20 randomly selected metal atom-containing particles by FE-SEM observation using an embedding resin, measuring the distance between both ends of each base, and taking the arithmetic average, using the same procedure as in the method for measuring the average height of the protrusions described above.

[0074] The protrusions can occupy 30% or more of the total surface area (100%) of the outer surface of the metal part. In this case, the metal atom-containing particles are more likely to come into contact with the sintered body. The area occupied by the protrusions relative to the outer surface of the metal part can be measured, for example, as follows: First, an orthographic image of the metal atom-containing particle is photographed using a field emission scanning electron microscope (FE-SEM). The 6000x magnification photograph taken with the FE-SEM is analyzed using commercially available image analysis software. After image processing such as flattening, the area of ​​the protrusions (area in a plan view) is determined, and the ratio of the area of ​​the protrusions to the area of ​​the metal atom-containing particle is defined as the area occupied by the protrusions. The area occupied by the protrusions relative to the outer surface of the metal part is determined for 20 metal atom-containing particles.

[0075] Another form of the metal atom-containing particle may include a base particle having a recess and a metal portion disposed on the surface of the base particle. In this form of metal atom-containing particle, the metal portion may also be formed in the recess. Specific examples will be described below.

[0076] Fig. 4 shows an example of a metal atom-containing particle 10 including a base particle 11 having a recess 14 and a metal portion 12 disposed on the surface of the base particle 11, and schematically illustrates the appearance of this metal atom-containing particle 10. In order to show a partial cross-sectional structure of the metal atom-containing particle 10, the portion surrounded by the dashed line in Fig. 4 is broken away.

[0077] In the metal atom-containing particle 10 of the embodiment shown in FIG. 4, a plurality of recesses 14 are formed on the surface of the base particle 11. The metal portion 12 is arranged so as to cover the surface of the base particle 11. In this embodiment, the metal portion 12 is formed in a two-layer structure of a first metal portion 12a and a second metal portion 12b, with the first metal portion 12a being arranged on the inside and the second metal portion 12b being arranged on the outside. In other words, the first metal portion 12a is in contact with the surface of the base particle 11, and the second metal portion 12b is present so as to cover the surface of the first metal portion 12a. The configuration of the metal portion 12 formed in a two-layer structure can be the same as that of the metal atom-containing particle 10 of the embodiment shown in FIG. 2 described above.

[0078] The metal portion 12 is also formed on the surface of the recess 14. In the embodiment of Fig. 4, the recess 14 has a first metal portion 12a formed therein.

[0079] In the case of metal atom-containing particles in which a metal portion is formed on the surface of a base particle having a plurality of recesses as described above, the metal atom-containing particles and the sintered body of the metal particles are more likely to come into contact with each other, and the effect of alleviating stress in the connection structure is also enhanced. In other words, the metal atom-containing particles having recesses make it easier for the metal atom-containing particles to conform to deformation, and as a result, even if stress is applied to the connection structure, warping and cracking are less likely to occur.

[0080] The method for preparing the base particle having recesses is not particularly limited. For example, recesses can be formed on the base particle by post-treating the base particle as described above.

[0081] The method for forming recesses by the post-treatment is not particularly limited, and for example, known methods can be used.Specific examples include a method of etching the surface of a base particle, a method of performing plasma treatment, ozone treatment and heat treatment in an oxygen atmosphere, a humidification treatment, a heat treatment in a vacuum, a heat treatment under pressurized and humidified conditions, a wet treatment with an oxidizing agent, and a physical treatment using a ball mill or the like.

[0082] The average depth of the recesses is not particularly limited. For example, the average depth of the recesses can be 0.1% or more and 80% or less of the average radius of the base particle. The depth of the recesses here refers to the distance from the surface of the spherical base particle to the bottom point of the recess, assuming that the base particle having the recesses is spherical. Specifically, the protrusions of 20 randomly selected metal atom-containing particles are observed by FE-SEM observation using an embedding resin in the same procedure as in the above-mentioned method for measuring the average height of the protrusions, and the depth of each recess is calculated as the arithmetic average.

[0083] Fig. 5 shows a further modified example of the metal atom-containing particle 10, and schematically illustrates the appearance of the metal atom-containing particle. In Fig. 5, the portion surrounded by the dashed line is broken away to show a partial cross-sectional structure of the metal atom-containing particle.

[0084] Specifically, the metal atom-containing particle 10 of Fig. 5 comprises a base particle 11 having a plurality of recesses 14 and a metal portion 12 disposed on the surface of the base particle 11, with a plurality of protrusions 13 formed on the outer surface of the metal portion 12. The metal portion 12 has a two-layer structure of a first metal portion 12a and a second metal portion 12b. In other words, the metal atom-containing particle 10 of Fig. 5 has the characteristics of both the metal atom-containing particles 10 of Figs. 3 and 4.

[0085] In the case of the metal atom-containing particle 10 having the configuration shown in Fig. 5, the presence of the plurality of protrusions 13 facilitates contact between the metal atom-containing particle and the sintered body of the metal particles, and the presence of the plurality of recesses 14 on the base particle 11 facilitates the metal atom-containing particle to conform to deformation. Therefore, the connection structure including the metal atom-containing particle 10 having the configuration shown in Fig. 5 is particularly likely to suppress the occurrence of warpage and cracks.

[0086] The metal atom-containing particle 10 in the form of FIG. 5 can be produced by the same method as the metal atom-containing particle 10 in the form of FIG. 3, except that the base particle 11 is replaced with a base particle 11 having a plurality of recesses 14.

[0087] Regardless of the form of the metal atom-containing particle 10, the hardness of the metal atom-containing particle 10 is not particularly limited. For example, the hardness of the metal atom-containing particle 10 is 10 N / mm 2 More than 6000N / mm 2 From the viewpoint of further suppressing the occurrence of cracks and warpage in the connection structure, the 10% K value of the metal atom-containing particles 10 is preferably 100 N / mm 2 More preferably, 1000N / mm 2 More than 5500N / mm 2 Below 5000N / mm 2 The following is the result.

[0088] The metal contained in the sintered body of metal particles is not particularly limited. For example, the metal contained in the sintered body of metal particles preferably includes one or more selected from the group consisting of gold, silver, tin, copper, germanium, indium, palladium, tellurium, thallium, bismuth, zinc, arsenic, selenium, and alloys containing at least one of these metal elements. In this case, the metal atom-containing particles and the sintered body of metal particles are more likely to come into contact with each other, further suppressing the occurrence of warping and cracks in the connection structure. It is particularly preferable that the metal contained in the sintered body of metal particles includes one or more selected from the group consisting of gold, silver, and copper. Furthermore, the sintered body of metal particles may be formed solely from metal.

[0089] In the adhesive layer, the metal atom-containing particles are present so as to be embedded in the sintered body of metal particles, and in particular, the metal atom-containing particles are present so that part or all of their surfaces are in contact with the sintered body of metal particles.

[0090] Specifically, the metal atom-containing particles and the sintered body are in contact with each other via chemical bonds. The type of such chemical bond is not limited, but may be a metallic bond. In particular, it is preferable that the metal contained in the metal portion or protrusion present on the surface of the metal atom-containing particles and the metal contained in the sintered body form a solid solution. In this case, the metal atom-containing particles and the sintered body are in stronger contact with each other, so that warping and cracking are even less likely to occur even when stress is applied to the connection structure.

[0091] A part of the surface of the metal atom-containing particle may be in contact with the sintered body, or the entire surface of the metal atom-containing particle may be in contact with the sintered body.

[0092] Specifically, in the connection structure of this embodiment, at the cross section of the adhesive layer, 5% or more of the circumferential length of the metal atom-containing particle is in contact with the sintered body, which results in strong contact between the metal atom-containing particle and the sintered body, making the connection structure less susceptible to warping and cracking even when stress is applied to it.

[0093] From the viewpoint of the surface area of ​​the metal atom-containing particle, it is preferable that 5% or more of the total surface area of ​​the metal atom-containing particle is in contact with the sintered body.

[0094] 6 schematically shows the cross-sectional structure of an adhesive layer 50 in the connection structure of this embodiment. The adhesive layer 50 has a metal atom-containing particle 10 and a sintered body 20. The metal atom-containing particle 10 is formed to have at least a base particle 11 and a metal portion 12.

[0095] In FIG. 6(a), most of the periphery of the metal atom-containing particle 10 (for example, 5% or more of the total periphery length) is in contact with the sintered body 20. In this configuration, even if stress is applied to the connection structure, warping and cracks are less likely to occur.

[0096] On the other hand, in Figure 6(b), only a portion of the periphery of the metal atom-containing particle 10 (for example, less than 5% of the total periphery) is in contact with the sintered body 20, and numerous voids 9 are formed near the surface of the metal atom-containing particle 10. In this configuration, when stress is applied to the connection structure, the metal atom-containing particle 10 is deformed, and then a force (recovery force) acts on the metal atom-containing particle 10 to return to its original shape. When returning to its original shape, if many voids 9 are formed and spaces are present, the particle's recovery ability is increased, and this recovery force can easily cause cracks or warping in the adhesive layer or other components that make up the connection structure.

[0097] In the cross section of the adhesive layer, it is preferable that 10% or more of the circumferential length of the metal atom-containing particle is in contact with the sintered body, more preferably 50% or more is in contact with the sintered body, and particularly preferably 90% or more is in contact with the sintered body.

[0098] The contact of the outer periphery of the metal atom-containing particle with the sintered body in the cross section of the adhesive layer can be confirmed, for example, by observing the cross section of the adhesive layer with a transmission electron microscope (FE-TEM). The contact between the metal atom-containing particle and the sintered body can be confirmed, for example, as follows.

[0099] First, metal atom-containing particles are added to the sintering material described below so that the content is 5 wt % and dispersed to prepare a sintering paste (bonding composition). Furthermore, a power semiconductor element with Ni / Au plating on its connection surface is prepared as the first member to be connected. An aluminum nitride substrate with Cu plating on its connection surface is prepared as the second member to be connected. The sintering paste is applied to the second member to be connected to form a sintering paste layer with a thickness of approximately 70 μm. The first member to be connected is then stacked on the sintering paste layer to obtain a laminate.

[0100] Next, the obtained laminate is preheated on a hot plate at 130°C for 60 seconds, and then the laminate is heated at 300°C for 3 minutes under a pressure of 10 MPa, thereby sintering the metal atom-containing particles contained in the sintering paste and forming a connection part containing the sintered product and the metal atom-containing particles, and the first and second connection target members are joined by the sintered product to obtain a connection structure.

[0101] The resulting connection structure is then placed in a Kulzer Technovit 4000 and cured to produce a resin for embedding the connection structure for inspection. The resin for embedding the connection structure for inspection is mechanically polished so as to pass through the center of the connection structure, and a cross section of the metal atom-containing particle is cut out using an ion milling device (Hitachi High-Technologies Corporation IM4000).

[0102] Next, using a transmission electron microscope FE-TEM (JEOL Ltd., "JEM-2010FEF"), the contact area between the metal atom-containing particle and the sintered body is subjected to line analysis or element mapping with an energy dispersive X-ray analyzer (EDS) to observe the diffusion state of the metal component.

[0103] By observing the diffusion state of the metal, it is possible to confirm that the outer peripheries of the metal atom-containing particles are in contact with the sintered body.

[0104] Furthermore, by mapping the diffusion state of the metal component, the contact ratio between the periphery of the metal atom-containing particle and the sintered body can be calculated by automatic calculation or the like, and this also makes it possible to quantify the contact ratio.

[0105] A sintered body of metal particles can be formed, for example, by sintering a sintering material containing metal particles at a predetermined temperature.

[0106] The metal particles contained in the sintering material may be particles of a simple metal or particles of a metal compound, which is a compound containing metal atoms and atoms other than the metal atoms.

[0107] Specific examples of metal compounds include metal oxides, metal carbonates, metal carboxylates, and metal complexes. The metal compound is preferably a metal oxide. For example, the metal oxide is converted into metal particles by heating during connection in the presence of a reducing agent and then sintered. The metal oxide is a precursor of metal particles. Examples of metal carboxylate particles include metal acetate particles.

[0108] The metal contained in the metal particles and metal compounds preferably includes one or more metals selected from the group consisting of gold, silver, tin, copper, germanium, indium, palladium, tellurium, thallium, bismuth, zinc, arsenic, selenium, and alloys containing at least one of these metal elements. In this case, the metal atom-containing particles and the sintered body of the metal particles are more likely to come into contact with each other, further suppressing warping and cracking of the connection structure. The metal contained in the sintered body of the metal particles is particularly preferably one or more metals selected from the group consisting of gold, silver, and copper. When silver particles and silver oxide particles are used, the sintered body is more likely to come into firm contact with the metal atom-containing particles. Examples of silver oxide include Ag2O and AgO.

[0109] The average particle diameter of the metal particles is preferably 10 nm or more and 10 μm or less. Furthermore, from the viewpoint of increasing the connection strength of the connection target components, it is preferable to have two or more types of metal particles with different average particle diameters. When two or more types of metal particles with different average particle diameters are used, the average particle diameter of the metal particles with the smallest average particle diameter is preferably 10 nm or more and 100 nm or less. The average particle diameter of the metal particles with the largeest average particle diameter is preferably 1 μm or more and 10 μm or less. The ratio of the amount of the metal particles with the smallest average particle diameter to the amount of the metal particles with the largeest average particle diameter is preferably 1 / 9 or more and 9 or less. The average particle diameter is determined by observing the metal particles with a scanning electron microscope and arithmetically averaging the maximum diameters of 50 randomly selected particles in the observed image.

[0110] The metal particles are preferably sintered by heating at a temperature of less than 400° C. The temperature at which the metal particles are sintered (sintering temperature) is more preferably 350° C. or less, and preferably 300° C. or more. When the temperature at which the metal particles are sintered is equal to or less than the above upper limit, sintering can be carried out efficiently, and further, the energy required for sintering can be reduced, and the environmental load can be reduced.

[0111] When the metal particles are metal oxide particles, the sintering material containing the metal particles preferably contains a reducing agent. Examples of the reducing agent include alcohols (compounds having an alcoholic hydroxyl group), carboxylic acids (compounds having a carboxyl group), and amines (compounds having an amino group). The reducing agents may be used alone or in combination of two or more.

[0112] Examples of the alcohols include alkyl alcohols. Specific examples of the alcohols include ethanol, propanol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, nonadecyl alcohol, and icosyl alcohol. The alcohols are not limited to primary alcohol compounds; secondary alcohol compounds, tertiary alcohol compounds, alkanediols, and alcohol compounds having a cyclic structure can also be used. Furthermore, compounds having multiple alcohol groups, such as ethylene glycol and triethylene glycol, can also be used as the alcohols. Compounds such as citric acid, ascorbic acid, and glucose can also be used as the alcohols.

[0113] Examples of the carboxylic acids include alkyl carboxylic acids. Specific examples of the carboxylic acids include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, and icosanoic acid. Furthermore, the carboxylic acids are not limited to primary carboxylic acid compounds, and secondary carboxylic acid compounds, tertiary carboxylic acid compounds, dicarboxylic acids, and carboxyl compounds having a cyclic structure can also be used.

[0114] Examples of the amines include alkylamines. Specific examples of the amines include butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, and icodecylamine. The amines may have a branched structure. Examples of amines having a branched structure include 2-ethylhexylamine and 1,5-dimethylhexylamine. The amines are not limited to primary amine compounds; secondary amine compounds, tertiary amine compounds, and amine compounds having a cyclic structure can also be used.

[0115] The reducing agent may be an organic substance having an aldehyde group, an ester group, a sulfonyl group, a ketone group, or the like, or may be an organic substance such as a metal carboxylate. While the metal carboxylate is used as a precursor of metal particles, it is also used as a reducing agent for metal oxide particles because it contains an organic substance.

[0116] The content of the reducing agent relative to 100 parts by weight of the metal particles is preferably 1 part by weight or more, more preferably 10 parts by weight or more, and preferably 1000 parts by weight or less, more preferably 500 parts by weight or less, and even more preferably 100 parts by weight or less. When the content of the reducing agent is equal to or more than the lower limit, the metal particles can be sintered even more densely.

[0117] If a reducing agent having a melting point lower than the sintering temperature (connection temperature) of the metal atom-containing particles is used, the particles tend to aggregate during connection, resulting in the formation of voids at the connection. By using a metal carboxylate, the metal carboxylate does not melt when heated during connection, preventing the formation of voids. In addition to the metal carboxylate, a metal compound containing an organic substance may also be used as a reducing agent.

[0118] The sintering material containing metal particles may contain other materials. For example, the sintering material may contain a resin component. When the resin component is contained, the occurrence of cracks, warping, and peeling of the adhesive layer in the connection structure is suppressed.

[0119] The resin component is not particularly limited. The resin component preferably contains a thermoplastic resin or a curable resin, and more preferably contains a curable resin. Examples of the curable resin include a photocurable resin and a thermosetting resin. The photocurable resin preferably contains a photocurable resin and a photopolymerization initiator. The thermosetting resin preferably contains a thermosetting resin and a thermosetting agent. Examples of the resin include known vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. Only one type of the resin may be used, or two or more types may be used in combination.

[0120] The sintering material containing metal particles may also contain a dispersion medium, such as a known solvent.

[0121] The sintering material containing the metal particles may be a commercially available product, such as "CT2700" manufactured by Kyocera Chemical Corporation, "ASP295," "ASP016," and "ASP043" manufactured by Heraeus, "LOCTITE ABLESTIK SSP2020" manufactured by Henkel, "H9890-6A" manufactured by Namics Corporation, "NH-4000," "NH-225D," and "NH-3000D" manufactured by Harima Chemicals, Inc., "CM-3212" and "CR-3520" manufactured by Kaken Tech Co., Ltd., and "Alconano Silver Paste ANP-1" manufactured by Nihon Superior Co., Ltd.

[0122] In the adhesive layer, the content of the metal atom-containing particles is preferably 0.1 wt% or more, more preferably 1 wt% or more, and preferably 20 wt% or less, more preferably 10 wt% or less. When the content of the metal atom-containing particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the occurrence of cracks and warping in the connection structure is further suppressed.

[0123] In the adhesive layer, the content of the metal particles is preferably greater than the content of the metal atom-containing particles, more preferably by 10% by weight or more, and even more preferably by 20% by weight or more.

[0124] In the adhesive layer, the content of the metal particles is preferably 70% by weight or more, more preferably 80% by weight or more, and preferably 98% by weight or less, more preferably 95% by weight or less. When the content of the metal atom-containing particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the occurrence of cracks and warping in the connection structure is further suppressed.

[0125] The method for manufacturing the connection structure of this embodiment is not particularly limited. One example of a method for manufacturing the connection structure is to form a laminate by placing a mixture of metal atom-containing particles and the sintering material described above between a first member to be connected and a second member to be connected, and then heat and pressurize the laminate. This sinters the metal particles contained in the laminate, forming an adhesive layer in which the metal atom-containing particles are dispersed in the sintered body, and the first member to be connected and the second member to be connected are connected by the adhesive layer.

[0126] In particular, in the connection structure of this embodiment, most of the surfaces of the metal atom-containing particles in the adhesive layer are in contact with the sintered body, and the contact is strong, so that pressure mounting is not necessarily required, and so-called pressureless mounting is possible. Therefore, the connection structure can be manufactured in an advantageous manner.

[0127] The metal atom-containing particles described above can increase the contact area between the metal particles and the sintered body in the adhesive layer included in the connection structure, making them suitable as a material for assembling the connection structure. Therefore, the metal atom-containing particles can provide a connection structure that is less likely to warp or crack.

[0128] The metal atom-containing particles are also suitable as a component of a bonding composition. Specifically, the bonding composition can be prepared by combining the metal atom-containing particles with the metal particles for sintering.

[0129] The bonding composition contains metal atom-containing particles and metal particles, and is therefore suitable as a material for assembling a connection structure. Specifically, the bonding composition is applied between a first member to be connected and a second member to be connected, and the metal particles in the bonding composition are sintered to form an adhesive layer containing the metal atom-containing particles.

[0130] The bonding composition can be prepared by mixing metal atom-containing particles and metal particles in a predetermined blending ratio. For example, the bonding composition can be prepared by mixing the metal atom-containing particles with a sintering material containing metal particles. The method for mixing the metal atom-containing particles and the metal particles is not particularly limited, and any known mixing method can be used.

[0131] In the bonding composition, the mixing ratio of the metal atom-containing particles and the metal particles is not particularly limited.

[0132] For example, the content of the metal atom-containing particles in 100% by weight of the components of the bonding composition excluding the dispersion medium is preferably 0.1% by weight or more, more preferably 1% by weight or more, and preferably 20% by weight or less, more preferably 10% by weight or less. When the content of the metal atom-containing particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the metal particles can be sintered more densely, and the contact area of ​​the metal atom-containing particles with the sintered body becomes larger.

[0133] Furthermore, the content of the metal particles in 100% by weight of the components of the bonding composition excluding the dispersion medium is preferably 70% by weight or more, more preferably 80% by weight or more, and preferably 98% by weight or less, more preferably 95% by weight or less. When the content of the metal particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the metal particles can be sintered even more densely.

[0134] When the bonding composition contains a resin component, the content of the resin component is preferably 1 wt % or more, more preferably 5 wt % or more, and preferably 20 wt % or less, more preferably 15 wt % or less, based on 100 wt % of the components of the bonding composition excluding the dispersion medium. When the content of the resin component is equal to or more than the lower limit and equal to or less than the upper limit, the metal particles can be sintered even more densely. [Example]

[0135] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0136] Example 1 As the base particles S1, divinylbenzene copolymer resin particles ("Micropearl SP-203" manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 3.0 μm were prepared.

[0137] 10 parts by weight of base particles S1 were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, and the solution was filtered to extract the base particles S1. Next, the base particles S1 were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles S1. The surface-activated base particles S1 were thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension (A1).

[0138] The suspension (A1) was placed in a solution containing 20 g / L of copper sulfate and 30 g / L of ethylenediaminetetraacetic acid to obtain a particle mixture (B1).

[0139] In addition, a copper plating solution (C1) was prepared as an electroless copper plating solution by adjusting the pH of a mixed solution containing 250 g / L of copper sulfate, 150 g / L of ethylenediaminetetraacetic acid, 100 g / L of sodium gluconate, and 50 g / L of formaldehyde with ammonia to 10.5.

[0140] Furthermore, a silver plating solution (D1) was prepared as an electroless silver plating solution by adjusting the pH of a mixed solution containing 30 g / L of silver nitrate, 100 g / L of succinimide, and 20 g / L of formaldehyde with aqueous ammonia to 8.0.

[0141] The copper plating solution (C1) was gradually added dropwise to the dispersed particle mixture (B1) adjusted to 55°C to perform electroless copper plating. The copper plating solution (C1) was added at a rate of 30 mL / min for 30 minutes to perform electroless copper plating. In this way, a particle mixture (E1) containing particles having copper metal moieties as first metal moieties on the surfaces of resin particles was obtained.

[0142] The particle mixture (E1) was then filtered to remove the particles, which were then washed with water to obtain particles having copper metal portions disposed on the surfaces of the base particles S1. After thoroughly washing the particles, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture (F1).

[0143] Next, the silver plating solution (D1) was gradually added dropwise to the dispersed particle mixture (F1) adjusted to 60°C to perform electroless silver plating. The silver plating solution (D1) was added at a rate of 10 mL / min for 30 minutes to perform electroless silver plating. The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having copper and silver metal portions (total thickness of the metal portion: 0.1 μm) on the surface of the base particle S1.

[0144] Example 2 Base particles S1 of Example 1 were prepared. Also, a suspension (A2) similar to the suspension (A1) of Example 1 was prepared.

[0145] Next, 1 part by weight of metallic nickel particle slurry (Mitsui Kinzoku Co., Ltd. "2020SUS", average particle diameter 150 nm) was added to the above suspension (A2) over 3 minutes to obtain a suspension (B2) containing base particles S1 to which a core substance was attached.

[0146] The suspension (B2) was placed in a solution containing 20 g / L of copper sulfate and 30 g / L of ethylenediaminetetraacetic acid to obtain a particle mixture (C2).

[0147] Also, a copper plating solution (D2) similar to the copper plating solution (C1) in Example 1 was prepared.

[0148] In addition, a silver plating solution (E2) similar to the silver plating solution (D1) in Example 1 was prepared.

[0149] The copper plating solution (D2) was gradually added dropwise to the dispersed particle mixture (C2) adjusted to 55°C to perform electroless copper plating. The copper plating solution (D2) was added at a rate of 30 mL / min for 30 minutes to perform electroless copper plating. In this way, a particle mixture (F2) was obtained, which contained particles having metal parts with protrusions on the surface, with copper metal parts arranged as first metal parts on the surfaces of resin particles.

[0150] The particle mixture (F2) was then filtered to remove the particles, which were then washed with water to obtain particles having copper metal portions disposed on the surface of the base particle S1 and metal portions with protrusions on the surface. After thoroughly washing the particles, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture (G2).

[0151] Next, the silver plating solution (E2) was gradually added dropwise to the dispersed particle mixture (G2) adjusted to 60°C to perform electroless silver plating. The silver plating solution (E2) was added at a rate of 10 mL / min for 30 minutes, and electroless silver plating was performed. The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having copper and silver metal portions (total thickness of the metal portion in the area without protrusions: 0.1 μm) arranged on the surface of the base particle S1 and having metal portions with multiple protrusions on the surface.

[0152] Example 3 Metal atom-containing particles were obtained in the same manner as in Example 2, except that the metallic nickel particle slurry was changed to an alumina particle slurry (average particle diameter 150 nm).

[0153] Example 4 Metal atom-containing particles were obtained in the same manner as in Example 2, except that the metallic nickel particle slurry was changed to a copper particle slurry (average particle diameter 150 nm).

[0154] Example 5 The suspension (A1) obtained in Example 1 was placed in a solution containing 40 ppm of nickel sulfate, 2 g / L of trisodium citrate, and 10 g / L of aqueous ammonia to obtain a particle mixture (B5).

[0155] The plating solution for forming acicular projections (C5) was prepared as an electroless copper-nickel-phosphorus alloy plating solution by adjusting the pH to 10.0 with ammonia water as a mixture containing 100 g / L of copper sulfate, 10 g / L of nickel sulfate, 10 g / L of sodium hypophosphite, 70 g / L of trisodium citrate, 10 g / L of boric acid, and 5 mg / L of polyethylene glycol 1000 (molecular weight: 1000) as a nonionic surfactant.

[0156] Furthermore, a silver plating solution (D5) was prepared as an electroless silver plating solution by adjusting a mixed solution of 30 g / L of silver nitrate, 100 g / L of succinimide, and 20 g / L of formaldehyde to pH 8.0 with aqueous ammonia.

[0157] The plating solution for forming acicular projections (C5) was gradually added dropwise to the dispersed particle mixture (B5) adjusted to 70°C, forming acicular projections. The plating solution for forming acicular projections (C5) was added at a rate of 40 mL / min for 60 minutes, and electroless copper-nickel-phosphorus alloy plating was performed (acicular projection formation and copper-nickel-phosphorus alloy plating process). The particles were then removed by filtration, yielding particles (E5) having a copper-nickel-phosphorus alloy metal portion disposed on the surface of the base particle S1 and a metal portion having protrusions (precipitated protrusions) on the surface. The particles (E5) were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (F5).

[0158] The suspension (F5) was then filtered to remove the particles, which were then washed with water to obtain particles in which a copper-nickel-phosphorus alloy metal portion was disposed on the surface of the base particle A, and the metal portion had needle-like protrusions on the surface. After thoroughly washing the particles, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture (G5).

[0159] Next, the silver plating solution (D5) was gradually added dropwise to the dispersed particle mixture (G5) adjusted to 60°C to perform electroless silver plating. The silver plating solution (D5) was added at a rate of 10 mL / min for 30 minutes, and electroless silver plating was performed. The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having a copper-nickel-phosphorus alloy portion and a silver metal portion (total thickness of the metal portion in the portion without protrusions: 0.1 μm) arranged on the surface of the base particle S1, and having a metal portion with multiple acicular protrusions on the surface.

[0160] Example 6 The suspension (A1) obtained in Example 1 was placed in a solution containing 500 ppm of potassium silver cyanide, 10 g / L of potassium cyanide, and 10 g / L of potassium hydroxide to obtain a particle mixture (B6).

[0161] A silver plating solution (C6) was prepared as the plating solution for forming acicular projections by adjusting the pH of a mixture containing 80 g / L of potassium silver cyanide, 10 g / L of potassium cyanide, 20 mg / L of polyethylene glycol 1000 (molecular weight: 1000), 50 ppm of thiourea, and 100 g / L of hydrazine monohydrate with potassium hydroxide to 7.5.

[0162] The electroless silver plating solution (C6) was gradually added dropwise to the dispersed particle mixture (B6) adjusted to 80°C to form acicular protrusions. The electroless silver plating solution (C6) was added at a rate of 10 mL / min for 60 minutes to perform electroless silver plating (acicular protrusion formation and silver plating process). The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles with silver metal portions (total thickness of the metal portion in the non-protrusion areas: 0.1 μm) arranged on the surface of the resin particles and with multiple acicular protrusions formed on the surface.

[0163] Example 7 The suspension (B2) obtained in Example 2 was placed in a solution containing 20 g / L of copper sulfate and 30 g / L of ethylenediaminetetraacetic acid to obtain a particle mixture (C7).

[0164] In addition, a copper plating solution (D7) was prepared as an electroless copper plating solution by adjusting the pH of a mixed solution containing 300 g / L of copper sulfate, 150 g / L of ethylenediaminetetraacetic acid, 120 g / L of sodium gluconate, and 70 g / L of formaldehyde with ammonia to 10.5.

[0165] The copper plating solution (D7) was gradually added dropwise to the dispersed particle mixture (C7) adjusted to 55°C, to perform electroless copper plating. The copper plating solution (D7) was added at a rate of 30 mL / min for 30 minutes, and electroless copper plating was performed. The particles were then removed by filtration, and a particle mixture (F7) was obtained, in which copper metal portions were arranged on the surfaces of the base particles A and particles had metal portions with protrusions on the surfaces.

[0166] The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having a copper metal portion (total thickness of the metal portion in the area without protrusions: 0.1 μm) disposed on the surface of the base particle A and a metal portion having multiple protrusions on the surface.

[0167] Example 8 The suspension (B2) obtained in Example 2 was placed in a solution containing 20 g / L of copper sulfate and 30 g / L of ethylenediaminetetraacetic acid to obtain a particle mixture (C8).

[0168] Furthermore, a copper plating solution (D8) was prepared as an electroless copper plating solution by adjusting the pH of a mixed solution containing 250 g / L of copper sulfate, 150 g / L of ethylenediaminetetraacetic acid, 100 g / L of sodium gluconate, and 50 g / L of formaldehyde with ammonia to 10.5.

[0169] Furthermore, a tin plating solution (E8) was prepared as an electroless tin plating solution by adjusting the pH of a mixed solution containing 20 g / L of tin chloride, 50 g / L of nitrilotriacetic acid, 2 g / L of thiourea, 1 g / L of thiomalic acid, 7.5 g / L of ethylenediaminetetraacetic acid, and 15 g / L of titanium trichloride with sulfuric acid to 7.0.

[0170] The copper plating solution (D8) was gradually added dropwise to the dispersed particle mixture (C8) adjusted to 55°C, to perform electroless copper plating. The copper plating solution (D8) was added at a rate of 30 mL / min for 30 minutes, and electroless copper plating was performed. The particles were then removed by filtration, and a particle mixture (F8) was obtained, in which copper metal portions were arranged on the surfaces of the base particles A and particles had metal portions with protrusions on the surfaces.

[0171] The particle mixture (F8) was then filtered to remove the particles, which were then washed with water to obtain particles with a copper metal portion disposed on the surface of the base particle A. After thoroughly washing the particles, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture (G8).

[0172] Next, the tin plating solution (E8) was gradually added dropwise to the dispersed particle mixture (G8) adjusted to 60°C to perform electroless tin plating. The tin plating solution (E8) was added at a rate of 10 mL / min for 30 minutes to perform electroless tin plating. The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having copper and tin metal portions (total thickness of the metal portion in the area without protrusions: 0.1 μm) arranged on the surface of the base particle A and having metal portions with multiple protrusions on the surface.

[0173] Example 9 The suspension (A1) obtained in Example 1 was added to a solution containing 25 g / L of nickel sulfate, 15 ppm of thallium nitrate, and 10 ppm of bismuth nitrate to obtain a particle mixture (B9).

[0174] Also, a nickel plating solution (C9) (pH 5.5) containing 100 g / L of nickel sulfate, 40 g / L of sodium hypophosphite, 15 g / L of sodium citrate, 25 ppm of thallium nitrate, and 10 ppm of bismuth nitrate was prepared.

[0175] Furthermore, a gold plating solution (D9) (pH 9.0) containing 10 g / L of potassium gold cyanide, 20 g / L of sodium citrate, 3.0 g / L of ethylenediaminetetraacetic acid, and 20 g / L of sodium hydroxide was prepared as an electroless displacement gold plating solution.

[0176] The nickel plating solution (C9) was gradually added dropwise to the dispersed particle mixture (B9) adjusted to 50°C to perform electroless nickel plating. The nickel plating solution (C8) was added at a rate of 12.5 mL / min for 30 minutes to perform electroless nickel plating (Ni plating step). In this way, a particle mixture (E9) containing particles having nickel metal moieties as first metal moieties on the surfaces of resin particles was obtained.

[0177] Thereafter, the particle mixture (E9) was filtered to remove the particles, which were then washed with water to obtain particles having nickel metal portions disposed on the surfaces of the base particles A. After thoroughly washing the particles with water, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture (F9).

[0178] Next, the gold plating solution (D9) was gradually added dropwise to the dispersed particle mixture (F9) adjusted to 60°C to perform electroless displacement gold plating. The gold plating solution (D9) was added at a rate of 2 mL / min for 45 minutes, and electroless displacement gold plating was performed. The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having nickel and gold metal portions (total thickness of the metal portion: 0.05 μm) on the surface of the base particle A.

[0179] Example 10 Base particle S1 of Example 1 was prepared. 10 parts by weight of base particle S1 was dispersed in 100 parts by weight of an alkaline solution containing 10% by weight of potassium permanganate using an ultrasonic disperser, and then the solution was filtered to extract base particle S1. The base particle S1 had recesses on its surface.

[0180] Next, 10 parts by weight of base particles S1 were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, and the solution was filtered to extract the base particles S1. Next, the base particles S1 were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surface of the base particles S1. The surface-activated base particles A were thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension (A10). Metal atom-containing particles were obtained in the same manner as in Example 1, except that the suspension (A10) was used instead of the suspension (A1).

[0181] Example 11 Base particle S1 of Example 1 was prepared. 10 parts by weight of base particle S1 was dispersed in 100 parts by weight of an alkaline solution containing 10% by weight of potassium permanganate using an ultrasonic disperser, and then the solution was filtered to extract base particle S1. The base particle S1 had recesses on its surface.

[0182] Next, 10 parts by weight of base particles S1 were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, and the solution was filtered to extract the base particles S1. Next, the base particles S1 were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles S1. The surface-activated base particles A were thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension (A11).

[0183] Next, 1 part by weight of metallic nickel particle slurry ("2020SUS" manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter 150 nm) was added to the above suspension (A11) over 3 minutes to obtain a suspension (B11) containing base particles A to which a core substance was attached.

[0184] The suspension (B11) was placed in a solution containing 5 g / L of copper sulfate and 8 g / L of ethylenediaminetetraacetic acid to obtain a particle mixture (C11).

[0185] In addition, a copper plating solution (D11) was prepared as an electroless copper plating solution by adjusting the pH of a mixed solution containing 50 g / L of copper sulfate, 30 g / L of ethylenediaminetetraacetic acid, 20 g / L of sodium gluconate, and 10 g / L of formaldehyde with ammonia to 10.5.

[0186] Furthermore, a silver plating solution (E11) was prepared as an electroless silver plating solution by adjusting a mixed solution containing 6 g / L of silver nitrate, 20 g / L of succinimide, and 5 g / L of formaldehyde to pH 8.0 with aqueous ammonia.

[0187] The copper plating solution (D11) was gradually added dropwise to the dispersed particle mixture (C11) adjusted to 55°C to perform electroless copper plating. The copper plating solution (D11) was added at a rate of 5 mL / min for 40 minutes to perform electroless copper plating. In this way, a particle mixture (F11) was obtained, in which copper metal parts were arranged as first metal parts on the surfaces of resin particles, and particles having metal parts with protrusions on the surfaces were included.

[0188] The particle mixture (F11) was then filtered to remove the particles, which were then washed with water to obtain particles having copper metal portions disposed on the surface of the base particle S1 and metal portions with protrusions on the surface. After thoroughly washing the particles, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture (G11).

[0189] Next, the silver plating solution (E11) was gradually added dropwise to the dispersed particle mixture (G11) adjusted to 60°C to perform electroless silver plating. The silver plating solution (E11) was added at a rate of 5 mL / min for 15 minutes, and electroless silver plating was performed. The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having recesses and copper and silver metal portions (total thickness of the metal portion in the portion without protrusions: 0.01 μm) arranged on the surface of the base particle S1, and having metal portions with multiple protrusions on the surface.

[0190] Example 12 Base particle S1 of Example 1 was prepared. 10 parts by weight of base particle S1 was dispersed in 100 parts by weight of an acid solution containing 10% by weight of potassium chromate using an ultrasonic disperser, and then the solution was filtered to extract base particle S1. The base particle S1 had recesses on its surface.

[0191] Next, 10 parts by weight of base particles S1 were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, and the solution was filtered to extract the base particles S1. Next, the base particles S1 were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles S1. The surface-activated base particles A were thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension (A12).

[0192] Next, 1 part by weight of metallic nickel particle slurry ("2020SUS" manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter 150 nm) was added to the above suspension (A12) over a period of 3 minutes to obtain a suspension (B12) containing base particles A to which a core substance was attached.

[0193] Metal atom-containing particles were obtained in the same manner as in Example 2, except that the suspension (B12) was used instead of the suspension (B2).

[0194] Example 13 1. Preparation of Silicone Oligomers A 100 ml separable flask placed in a warm bath was charged with 1 part by weight of 1,3-divinyltetramethyldisiloxane and 20 parts by weight of 0.5 wt % p-toluenesulfonic acid aqueous solution. After stirring at 40°C for 1 hour, 0.05 parts by weight of sodium bicarbonate was added. Next, 10 parts by weight of dimethoxymethylphenylsilane, 49 parts by weight of dimethyldimethoxysilane, 0.6 parts by weight of trimethylmethoxysilane, and 3.6 parts by weight of methyltrimethoxysilane were added and stirred for 1 hour. Next, 1.9 parts by weight of 10 wt % potassium hydroxide aqueous solution was added, and the mixture was heated to 85°C and stirred for 10 hours while reducing the pressure with an aspirator. After the reaction was completed, the mixture was returned to normal pressure and cooled to 40°C. 0.2 parts by weight of acetic acid was added and allowed to stand in a separatory funnel for at least 12 hours. The lower layer was removed after separation and purified using an evaporator to obtain a silicone oligomer. 2. Preparation of silicone particle materials (including organic polymers) Solution A was prepared by dissolving 0.5 parts by weight of tert-butyl-2-ethylperoxyhexanoate (polymerization initiator, NOF Corporation's "Perbutyl O") in 30 parts by weight of the resulting silicone oligomer. Aqueous solution B was prepared by mixing 0.8 parts by weight of a 40% by weight aqueous solution of triethanolamine lauryl sulfate (emulsifier) ​​and 80 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol (polymerization degree: approximately 2000, saponification degree: 86.5-89 mol%, Nippon Synthetic Chemical Industry Co., Ltd.'s "GOHSENOL GH-20") in 150 parts by weight of ion-exchanged water. Solution A was placed in a separable flask placed in a warm bath, and then aqueous solution B was added. Emulsification was then carried out using a Shirasu Porous Glass (SPG) membrane (average pore size: approximately 1 μm). The mixture was then heated to 85°C and polymerized for 9 hours. The entire polymerized particles were washed with water by centrifugation and freeze-dried. After drying, the particle aggregates were pulverized in a ball mill until the desired ratio (average secondary particle size / average primary particle size) was achieved, yielding silicone particles (base particle S2) with a particle size of 3.0 μm.

[0195] A metal portion was formed in the same manner as in Example 2, except that the base particle S1 was changed to the base particle S2, to obtain metal atom-containing particles.

[0196] Example 14 Silicone particles (base particles S3) with a particle size of 3.0 μm were obtained in the same manner as in Example 13, except that a silicone oil terminated in acryl (X-22-2445 manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the silicone oligomer.

[0197] A metal portion was formed in the same manner as in Example 2, except that the base particle S1 was changed to the base particle S3, to obtain metal atom-containing particles.

[0198] Example 15 Base particles S4, which differ from base particles S1 only in particle size, were prepared. The particle size was 2.0 μm.

[0199] Metal atom-containing particles were obtained by forming a metal portion in the same manner as in Example 2, except that the base particle S1 was changed to the base particle S4. Example 16 Base particles S5, which differ from base particles S1 only in particle size, were prepared, with a particle size of 10.0 μm.

[0200] A metal portion was formed in the same manner as in Example 2, except that the base particle S1 was changed to the base particle S5, to obtain metal atom-containing particles.

[0201] Example 17 Base particles S6, which differ from base particles S1 only in particle size, were prepared, with a particle size of 35.0 μm.

[0202] A metal portion was formed in the same manner as in Example 1, except that the base particle S1 was changed to the base particle S6, to obtain metal atom-containing particles.

[0203] Example 18 A metal portion was formed in the same manner as in Example 8, except that the base particle S1 was changed to the base particle S6 of Example 17, to obtain metal atom-containing particles.

[0204] Example 19 100 g of ethylene glycol dimethacrylate, 800 g of isobornyl acrylate, 100 g of cyclohexyl methacrylate, and 35 g of benzoyl peroxide were mixed and uniformly dissolved to obtain a monomer mixture. 5 kg of a 1 wt % aqueous solution of polyvinyl alcohol was prepared and placed in a reaction vessel. The aforementioned monomer mixture was added to the mixture and stirred for 2 to 4 hours to adjust the particle size so that the monomer droplets had the desired particle size. After this, the mixture was reacted for 9 hours under a nitrogen atmosphere at 90°C to obtain particles. The obtained particles were washed several times with hot water and then classified to obtain base particles S7 with an average particle size of 35.0 μm.

[0205] A metal portion was formed in the same manner as in Example 1, except that the base particle S1 was changed to the base particle S7, to obtain metal atom-containing particles.

[0206] Example 20 A metal portion was formed in the same manner as in Example 9, except that the base particle S1 was changed to the base particle S7 of Example 19, to obtain metal atom-containing particles.

[0207] Example 21 Base particle S8 having a particle diameter of 50.0 μm was prepared, which differed only in particle diameter from base particle S7 of Example 19. A metal portion was formed in the same manner as in Example 1, except that base particle S7 was replaced with base particle S8, to obtain metal atom-containing particles.

[0208] (Comparative Example 1) As the base particles S1, divinylbenzene copolymer resin particles ("Micropearl SP-203" manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 3.0 μm were prepared.

[0209] (Comparative Example 2) 10 parts by weight of the above base particles S1 were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, and the solution was filtered to extract the base particles S1. Next, the base particles S1 were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles S1. The surface-activated base particles S1 were thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension (a1).

[0210] The suspension (a1) was placed in a solution containing 50 g / L of nickel sulfate, 30 ppm of thallium nitrate, and 20 ppm of bismuth nitrate to obtain a particle mixture (b1).

[0211] Also, a nickel plating solution (c1) (pH 6.5) containing 200 g / L of nickel sulfate, 85 g / L of sodium hypophosphite, 30 g / L of sodium citrate, 50 ppm of thallium nitrate, and 20 ppm of bismuth nitrate was prepared.

[0212] The nickel plating solution (c1) was gradually added dropwise to the dispersed particle mixture (b1) adjusted to 50°C to perform electroless nickel plating. The nickel plating solution (c1) was added dropwise at a rate of 25 mL / min for 60 minutes to perform electroless nickel plating (Ni plating step). The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles (total thickness of the metal part: 0.1 μm) in which a nickel-phosphorus metal part was disposed on the surface of the base particle S1 and the metal part had protrusions on the surface.

[0213] (Comparative Example 3) 1 g of metallic nickel particle slurry (Mitsui Kinzoku Co., Ltd. "2020SUS", average particle diameter 150 nm) was added to a suspension (a1) similar to that in Comparative Example 1 over a period of 3 minutes to obtain a suspension (b2) containing base particles S1 to which a core substance was attached.

[0214] The suspension (b2) was placed in a solution containing 50 g / L of nickel sulfate, 30 ppm of thallium nitrate, and 20 ppm of bismuth nitrate to obtain a particle mixture (c2).

[0215] Also, a nickel plating solution (d2) (pH 6.5) containing 200 g / L of nickel sulfate, 85 g / L of sodium hypophosphite, 30 g / L of sodium citrate, 50 ppm of thallium nitrate, and 20 ppm of bismuth nitrate was prepared.

[0216] The nickel plating solution (d2) was gradually added dropwise to the dispersed particle mixture (c2) adjusted to 50°C to perform electroless nickel plating. The nickel plating solution (d2) was added dropwise at a rate of 25 mL / min for 60 minutes to perform electroless nickel plating (Ni plating step). The particles were then filtered to remove them, washed with water, and dried to obtain metal atom-containing particles having a nickel-phosphorus metal portion disposed on the surface of the base particle A and having a metal portion with protrusions on the surface (total thickness of the metal portion in the area without protrusions: 0.1 μm).

[0217] (Evaluation method) (1) Measurement of the height of the protrusion The obtained metal atom-containing particles were added to Kulzer's "Technovit 4000" so that the content was 30 wt % and dispersed to prepare a resin for embedding metal atom-containing particles for inspection. A cross section of the metal atom-containing particles was cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the center of the metal atom-containing particles dispersed in the resin for inspection.

[0218] Then, using a field emission transmission electron microscope (FE-TEM) (JEOL Ltd., "JEM-ARM200F") set at an image magnification of 50,000 times, 20 metal atom-containing particles were randomly selected and the protrusions of each metal atom-containing particle were observed. The heights of the protrusions of the obtained metal atom-containing particles were measured and the arithmetic mean was calculated to obtain the average protrusion height.

[0219] (2) Measurement of the average diameter of the base of the protrusion The obtained metal atom-containing particles were added to Kulzer's "Technovit 4000" so that the content was 30 wt % and dispersed to prepare a resin for embedding metal atom-containing particles for inspection. A cross section of the metal atom-containing particles was cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the center of the metal atom-containing particles dispersed in the resin for inspection.

[0220] Then, using a field emission transmission electron microscope (FE-TEM) (JEOL Ltd., "JEM-ARM200F") set at an image magnification of 50,000 times, 20 metal atom-containing particles were randomly selected and the protrusions of each metal atom-containing particle were observed. The base diameters of the protrusions of the obtained metal atom-containing particles were measured and the arithmetic mean was taken as the average diameter of the protrusion bases.

[0221] (3) Observation of the shape of the protrusion Using a scanning electron microscope (FE-SEM), the image magnification was set to 25,000x, 20 metal atom-containing particles were randomly selected, the protrusions of each metal atom-containing particle were observed, and the type of shape to which all of the protrusions belonged was investigated.

[0222] (4) Measurement of the thickness of the entire metal part where there are no protrusions The obtained metal atom-containing particles were added to Kulzer's "Technovit 4000" so that the content was 30 wt % and dispersed to prepare a resin for embedding metal atom-containing particles for inspection. A cross section of the metal atom-containing particles was cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the center of the metal atom-containing particles dispersed in the resin for inspection.

[0223] Then, using a field emission transmission electron microscope (FE-TEM) (JEOL Ltd., "JEM-ARM200F") set at an image magnification of 50,000 times, 20 metal atom-containing particles were randomly selected, and the metal portion of each metal atom-containing particle in the portion without protrusions was observed. The thickness of the entire metal portion in the portion without protrusions of the obtained metal atom-containing particles was measured, and the arithmetic average was taken as the thickness of the entire metal portion in the portion without protrusions.

[0224] (4-1) Measurement of the ratio of the area occupied by protrusions to the area of ​​metal atom-containing particles Using a scanning electron microscope (FE-SEM) with an image magnification of 6000x, 20 metal atom-containing particles were randomly selected and photographed. The FE-SEM photographs were then analyzed using commercially available image analysis software.

[0225] After image processing such as flattening, the area of ​​the protrusions was determined, and the ratio of the area of ​​the protrusions to the area of ​​the metal atom-containing particle was calculated for 20 metal atom-containing particles, and the average value was taken as the occupied area ratio.

[0226] (5) Average nickel content throughout the metal part 5 g of metal atom-containing particles were added to a mixture of 5 mL of 60% nitric acid and 10 mL of 37% hydrochloric acid, and the conductive layer was completely dissolved to obtain a solution. The nickel content of the obtained solution was analyzed using an ICP-MS analyzer (manufactured by Hitachi, Ltd.).

[0227] (6) Measurement of the depth of recesses on the surface of the base material particle The obtained metal atom-containing particles were added to Kulzer's "Technovit 4000" so that the content was 30 wt % and dispersed to prepare a resin for embedding metal atom-containing particles for inspection. A cross section of the metal atom-containing particles was cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the center of the metal atom-containing particles dispersed in the resin for inspection.

[0228] Then, using a field emission transmission electron microscope (FE-TEM) (JEOL Ltd., "JEM-ARM200F") set at an image magnification of 50,000 times, 50 metal atom-containing particles were randomly selected, and the recesses in the surface portion of the base particle of each metal atom-containing particle were observed. The depths of the recesses in the surface portion of the base particle of the obtained metal atom-containing particles were measured, and the arithmetic average was taken as the depth of the recesses in the surface portion of the base particle.

[0229] (7) Compressive elastic modulus of metal atom-containing particles (10% K value) The compressive elastic modulus (10% K value) of the obtained metal atom-containing particles was measured at 23°C using a microcompression tester (Fisherscope H-100 manufactured by Fisher) to determine the 10% K value.

[0230] (8) Measurement of the contact ratio between the outer periphery of the metal atom-containing particle and the sintered body in the connection structure A1 during pressure mounting The obtained metal atom-containing particles were added to "ANP-1" (silver paste) manufactured by Nippon Superior Co., Ltd. so that the content was 5 wt % and dispersed to prepare a sintering paste (bonding composition).

[0231] The first connection target component was a power semiconductor element with Ni / Au plating on the connection surface, and the second connection target component was an aluminum nitride substrate with Cu plating on the connection surface.

[0232] The sintering paste was applied to the second member to be connected to form a sintering paste layer with a thickness of approximately 70 μm, and then the first member to be connected was laminated on the sintering paste layer to obtain a laminate.

[0233] The obtained laminate was preheated on a hot plate at 130°C for 60 seconds, and then heated at 300°C for 3 minutes under a pressure of 10 MPa, thereby sintering the metal atom-containing particles contained in the sintering paste and forming a connection part containing the sintered material and the metal atom-containing particles, and the first and second connection target members were joined by the sintered material to obtain connection structure A1.

[0234] The resulting connection structure A1 was placed in a Kulzer Technovit 4000 and cured to prepare a resin for embedding the connection structure for inspection. A cross section of the metal atom-containing particle was cut out from the resin for embedding the connection structure for inspection using an ion milling machine (Hitachi High-Technologies Corporation IM4000) so as to pass through the center of the connection structure A1.

[0235] Using a transmission electron microscope FE-TEM (JEOL Ltd., "JEM-2010FEF"), the diffusion state of the metal was observed by elemental mapping of the contact area between the metal atom-containing particle and the sintered body with an energy dispersive X-ray analyzer (Horiba Ltd., "EX-470").

[0236] By mapping the diffusion state of the metal, the contact ratio between the outer periphery of the metal atom-containing particle and the sintered body was calculated.

[0237] [Contact ratio criteria] ○○○: Contact rate is over 80% and less than 100%. ○○: Contact rate is over 50% and less than 80%. ○: Contact rate is over 30% and less than 50%. △: Contact rate is 5% or more and 30% or less. ×: Contact rate is less than 5%.

[0238] (9) Flatness of the power semiconductor element in the connection structure A1 The flatness of the power semiconductor element of the connection structure A1 obtained in the evaluation of (8) above was measured using a high-precision laser displacement meter (Keyence Corporation: LK-G5000) to measure the maximum and minimum displacements. From the obtained measurements, the flatness was calculated using the following formula. Flatness (μm) = Maximum displacement (μm) - Minimum displacement (μm) [Flatness criteria] ○○○: Flatness is 0.5 μm or less. ○○: Flatness is greater than 0.5 μm and less than 1 μm. ○: Flatness is more than 1 μm and 5 μm or less. △: Flatness is greater than 5 μm and less than 10 μm. ×: Flatness exceeds 10 μm.

[0239] (10) Connection reliability in connection structure A1 The connection structure A1 obtained in the evaluation in (8) above was placed in a thermal shock testing machine (TSA-101S-W manufactured by Espec Corporation), and after 3,000 cycles consisting of a minimum temperature of -40°C for a holding time of 30 minutes and a maximum temperature of 200°C for a holding time of 30 minutes, the bonding strength was measured using a shear strength testing machine (STR-1000 manufactured by Rhesca Corporation).

[0240] [Connection reliability criteria] ○○○: Bond strength exceeds 50 MPa. ○○: Bond strength is over 40 MPa and less than 50 MPa. ○: Bond strength is greater than 30 MPa and less than 40 MPa. △: Bond strength is greater than 20 MPa and less than 30 MPa. ×: Bond strength is 20 MPa or less.

[0241] (11) Measurement of the contact ratio between the outer periphery of the metal atom-containing particle and the sintered body in the connection structure A2 in pressureless mounting The obtained metal atom-containing particles were added to "ANP-1" (silver paste) manufactured by Nippon Superior Co., Ltd. so that the content was 5 wt % and dispersed to prepare a sintering paste (bonding composition).

[0242] The first connection target component was a power semiconductor element with Ni / Au plating on the connection surface, and the second connection target component was an aluminum nitride substrate with Cu plating on the connection surface.

[0243] The sintered silver paste was applied to the second member to be connected to form a sintering paste layer with a thickness of about 70 μm. Then, the first member to be connected was laminated on the sintering paste layer to obtain a laminate.

[0244] The obtained laminate was placed in a reflow furnace in a nitrogen atmosphere, and then the laminate was heated at a heating rate of 10°C / min and a peak temperature of 250°C for 60 minutes, thereby sintering the metal atom-containing particles contained in the sintering paste and forming a connection part containing the sintered product and the metal atom-containing particles, and the first and second connection target components were joined by the sintered product to obtain connection structure A2.

[0245] The resulting connection structure A2 was placed in a Kulzer Technovit 4000 and cured to prepare a resin for embedding the connection structure for inspection. A cross section of the metal atom-containing particle was cut out from the resin for embedding the connection structure for inspection using an ion milling machine (Hitachi High-Technologies Corporation IM4000) so as to pass through the center of the connection structure.

[0246] Using a transmission electron microscope FE-TEM (JEOL Ltd., "JEM-2010FEF"), the diffusion state of the metal was observed by elemental mapping of the contact area between the metal atom-containing particle and the sintered body with an energy dispersive X-ray analyzer (Horiba Ltd., "EX-470").

[0247] By mapping the diffusion state of the metal, the contact ratio between the outer periphery of the metal atom-containing particle and the sintered body was calculated.

[0248] [Contact ratio criteria] ○○○: Contact rate is over 80% and less than 100%. ○○: Contact rate is over 50% and less than 80%. ○: Contact rate is over 30% and less than 50%. △: Contact rate is 5% or more and 30% or less. ×: Contact rate is less than 5%.

[0249] (12) Flatness of the power semiconductor element in the connection structure A2 The flatness of the power semiconductor element of the connection structure A2 obtained in the evaluation in (11) above was measured using a high-precision laser displacement meter (Keyence Corporation: LK-G5000) to measure the maximum and minimum displacements. From the obtained measurements, the flatness was calculated using the following formula. Flatness (μm) = Maximum displacement (μm) - Minimum displacement (μm) [Flatness criteria] ○○○: Flatness is 0.5 μm or less. ○○: Flatness is greater than 0.5 μm and less than 1 μm. ○: Flatness is more than 1 μm and 5 μm or less. △: Flatness is greater than 5 μm and less than 10 μm. ×: Flatness exceeds 10 μm.

[0250] (13) Connection reliability in connection structure A2 The connection structure A2 obtained in the evaluation in (11) above was placed in a thermal shock testing machine (TSA-101S-W manufactured by Espec Corporation), and after 3,000 cycles consisting of a minimum temperature of -40°C for a holding time of 30 minutes and a maximum temperature of 200°C for a holding time of 30 minutes, the bonding strength was measured using a shear strength testing machine (STR-1000 manufactured by Rhesca Corporation).

[0251] [Connection reliability criteria] ○○○: The bonding strength exceeds 40 MPa. ○○: Bond strength is over 30 MPa and 40 MPa or less. ○: Bond strength is greater than 20 MPa and less than 30 MPa. △: Bond strength is greater than 10 MPa and less than 20 MPa. ×: Bond strength is 10 MPa or less.

[0252] [Table 1]

[0253] Table 1 shows the results of performance evaluation of the connection structures A1 and A2 obtained using the metal atom-containing particles obtained in each of the examples and comparative examples.

[0254] The connection structures A1 and A2 obtained using the metal atom-containing particles obtained in each example have excellent flatness and connection reliability, which indicates that warpage and cracking are suppressed. In particular, the connection structure A2 produced under non-pressure conditions was shown to have excellent performance. [Explanation of symbols]

[0255] A: Connection structure 10: Metal atom-containing particles 11: Base material particles 12: Metal part 12a: First metal part 12b: Second metal part 13: Protrusion 14: Recess 20: Sintered body 50: Adhesive layer

Claims

1. A connection structure having an adhesive layer including metal atom-containing particles and a sintered body of metal particles, The metal atom-containing particle includes a base particle and a metal portion disposed on a surface of the base particle, the base particles are resin particles, the resin particles are polymers obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group, The metal part has a plurality of protrusions on its outer surface, The metal portion is formed in a two-layer structure of a first metal portion disposed on the inside and a second metal portion disposed on the outside, the second metal portion disposed on the outside is silver or tin, the total amount of nickel, chromium, platinum, and rhodium in the metal portion is 30 mass% or less with respect to the total mass of the metal portion, the sintered body of metal particles is a sintered body of a sintering material containing metal particles, the sintering material containing metal particles is a silver paste, the metal atom-containing particles and the sintered body are in contact with each other via a chemical bond, A connection structure in which 5% or more of the circumferential length of the metal atom-containing particle is in contact with the sintered body in a cross section of the adhesive layer.

2. A connection structure having an adhesive layer including metal atom-containing particles and a sintered body of metal particles, The metal atom-containing particle includes a base particle and a metal portion disposed on a surface of the base particle, the base particles are resin particles, the resin particles are polymers obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group, The metal part has a plurality of protrusions on its outer surface, the metal portion is formed by one layer, the metal portion is silver, the total amount of nickel, chromium, platinum, and rhodium in the metal portion is 30 mass% or less with respect to the total mass of the metal portion, the sintered body of metal particles is a sintered body of a sintering material containing metal particles, the sintering material containing metal particles is a silver paste, the metal atom-containing particles and the sintered body are in contact with each other via a chemical bond, A connection structure in which 5% or more of the circumferential length of the metal atom-containing particle is in contact with the sintered body in a cross section of the adhesive layer.

3. A connection structure having an adhesive layer including metal atom-containing particles and a sintered body of metal particles, The metal atom-containing particle includes a base particle and a metal portion disposed on a surface of the base particle, the base particles are resin particles, the resin particles are polymers obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group, The metal part has no protrusions on its outer surface, The metal portion is formed in a two-layer structure of a first metal portion disposed on the inside and a second metal portion disposed on the outside, the second metal portion disposed on the outside is gold or silver, the total amount of nickel, chromium, platinum, and rhodium in the metal portion is 30 mass% or less with respect to the total mass of the metal portion, the sintered body of metal particles is a sintered body of a sintering material containing metal particles, the sintering material containing metal particles is a silver paste, the metal atom-containing particles and the sintered body are in contact with each other via a chemical bond, A connection structure in which 5% or more of the circumferential length of the metal atom-containing particle is in contact with the sintered body in a cross section of the adhesive layer.

4. The connection structure according to claim 1 or 2, wherein the average diameter of the base of the projections is 3 nm or more and 5000 nm or less.

5. The connection structure according to claim 1 or 2, wherein the average height of the protrusions is 1 nm or more and 1000 nm or less.

6. The connection structure according to claim 1 or 2, wherein the projections occupy 30% or more of the total surface area (100%) of the outer surface of the metal part.

7. The connection structure according to any one of claims 1 to 6, wherein a plurality of recesses are formed on the surface of the base particle.

8. Metal atom-containing particles used in the connection structure according to any one of claims 1 to 7.

9. A bonding composition comprising the metal atom-containing particles according to claim 8 and metal particles.

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