JP7461272B2 - Silver-containing particles and pasty compositions - Google Patents

Description

The present invention relates to silver-containing particles. The present invention relates to a paste-like composition using the silver-containing particles.

In recent years, power semiconductor devices using wide band gap semiconductors such as silicon carbide and gallium nitride have come into use. Power semiconductor devices are manufactured, for example, by bonding a substrate and a semiconductor element with a bonding material. The bonding material must be a material with excellent electrical conductivity, heat dissipation, and heat resistance in order to stably operate the power semiconductor device. The bonding material may contain conductive particles along with sinterable silver particles, etc.

As a conductive particle that can be used in the above-mentioned bonding material, the following Patent Document 1 discloses a conductive particle that is dispersed in a bonding material containing metal atom-containing particles and used by sintering the metal atom-containing particles. This conductive particle includes a base particle and a conductive layer disposed on the surface of the base particle, the base particle has a thermal decomposition temperature of 200° C. or higher, and the compressive elastic modulus when the conductive particle is compressed by 10% is 300 N/mm ² or more and 3500 N/mm ² or less.

Further, Patent Document 2 below discloses silver-coated resin particles that include heat-resistant resin core particles and a silver coating layer formed on the surface of the resin core particles. In the silver-coated resin particles, the average particle size of the resin core particles is 0.1 to 10 μm, and the amount of silver contained in the silver coating layer is 60 to 100 parts by mass based on 100 parts by mass of the silver-coated resin particles. 90 parts by mass, and the exothermic peak temperature when differential thermal analysis of the silver-coated resin particles is 265° C. or higher.

JP 2016-015256 A JP 2016-130354 A

Electronic components such as semiconductor devices are manufactured by bonding members to be bonded together using a bonding material that contains conductive particles. The members to be bonded together are bonded together by heating the bonding material, thereby hardening or sintering the material. Therefore, the bonding material is exposed to a high-temperature environment during bonding. In addition, the bonded portion formed by the bonding material is also exposed to a high-temperature environment for long periods of time during long-term reliability testing and when the semiconductor device is operated.

With conventional joining materials, differences in the thermal expansion coefficients of the components being joined can cause cracks in the joint or interfacial peeling at the interface between the components being joined and the joint.

In addition, if the conductive particles contained in the bonding material are conductive particles that have a flexible base particle such as a resin particle and a metal layer disposed on the outer surface of the base particle, the occurrence of cracks and interfacial peeling can be suppressed to some extent.

However, in conventional conductive particles that use resin particles as base particles, when exposed to a high-temperature environment, outgassing occurs from the resin particles, causing the internal pressure of the conductive particles to rise and cracks to form in the metal layer, which can reduce the heat dissipation of the joint. In addition, in conventional conductive particles that use resin particles as base particles, the outgassing occurs and is released into the bonding material, which can cause voids to form in the bonding area. For this reason, it is difficult to improve the bonding reliability over a long period of time with bonding materials that use conventional conductive particles.

An object of the present invention is to provide silver-containing particles that can suppress the generation of voids and improve bonding reliability over a long period of time when used to bond members to be bonded. Another object of the present invention is to provide a paste composition using the above-mentioned silver-containing particles.

According to a broad aspect of the present invention, the present invention comprises base particles different from metal particles, and a metal portion disposed on the surface of the base particle, and the metal portion contains silver, and the measurement method described below is used. Silver-containing particles are provided in which the total amount of outgas measured in 5 mg of the base particles is 20,000 ppm or less.

Method for measuring the total amount of outgas from 5 mg of base particles: Two samples are prepared: 5 mg of the base particles and toluene at a known concentration. Using a thermal desorption device, the sample was heated at 250°C for 10 minutes while passing helium gas at a flow rate of 20 mL/min, and the generated components were adsorbed into a glass tube filled with an adsorbent. Collect. While passing helium gas into the glass tube in which the components were collected, the glass tube in which the components were collected was heated at 350° C. for 40 minutes to remove the components desorbed from the adsorbent. Directly introduced into a gas chromatograph mass spectrometer and analyzed. The peak area value of each component detected when using 5 mg of the base material particles as the sample is compared with the peak area value detected when toluene of the known concentration is used as the sample, and the base material particles are determined. Calculate the total amount of outgas for 5 mg of material particles.

In a particular aspect of the silver-containing particle according to the present invention, the metal part includes a first metal part and a second metal part disposed on the inner surface of the first metal part, The first metal part contains silver, and the second metal part contains nickel, copper, or an alloy thereof.

In a particular aspect of the silver-containing particles according to the present invention, the ratio of the thickness of the first metal portion to the thickness of the second metal portion is 0.15 or more and 6.0 or less.

In a particular aspect of the silver-containing particles according to the present invention, the metal portion has protrusions on the outer surface.

In a particular aspect of the silver-containing particles of the present invention, the particle diameter is 1 μm or more and 50 μm or less.

In a specific aspect of the silver-containing particles according to the present invention, the compressive modulus when compressed by 20% at 25° C. is 500 N/mm ² or more and 10,000 N/mm ² or less.

In a particular aspect of the silver-containing particles according to the present invention, the sum of Na ion concentration and K ion concentration in the aqueous phase of the filtrate is measured by the following method for measuring ion concentration in the aqueous phase of the filtrate. is 30 μg/g or less, and the Cl ion concentration in the aqueous phase of the filtrate is 60 μg/g or less.

Method for measuring ion concentration in aqueous phase of filtrate: 1 g of silver-containing particles and 10 mL of ion-exchanged water having a specific resistance of 18 MΩ are placed in a sealable container, and then the container is sealed. Heat the sealed container in an oven at 121° C. for 24 hours. The heated liquid contained in the container is filtered through a membrane filter with a pore size of 0.1 μm. The Na ion concentration and K ion concentration in the aqueous phase of the obtained filtrate are measured using an ICP emission spectrometer. The Cl ion concentration in the aqueous phase of the obtained filtrate is measured using an ion chromatograph.

In a particular aspect of the silver-containing particles according to the present invention, the amount of outgas derived from siloxane is 20% by volume or less out of 100% by volume of the total amount of outgas.

In certain aspects of the silver-containing particles according to the present invention, the base particles are different from silicone particles.

The silver-containing particles according to the present invention are preferably used in combination with a composition containing metal atom-containing particles.

According to a broad aspect of the present invention, there is provided a paste-like composition comprising the silver-containing particles described above.

In a particular aspect of the paste-like composition according to the present invention, the paste-like composition contains metal atom-containing particles.

In a particular aspect of the paste composition according to the present invention, the metal atom-containing particles include silver particles.

In a particular aspect of the paste-like composition according to the present invention, the paste-like composition includes a binder.

In a particular aspect of the paste composition according to the present invention, the paste composition is a bonding material.

The silver-containing particles according to the present invention include base particles different from metal particles and metal parts disposed on the surface of the base particles, and the metal parts contain silver. In the silver-containing particles according to the present invention, the total amount of outgas of 5 mg of the base particles measured by the above measuring method is 20,000 ppm or less. Since the silver-containing particles according to the present invention have the above-mentioned configuration, when used for joining members to be joined, it is possible to suppress the generation of voids and improve the joining reliability over a long period of time. I can do it.

FIG. 1 is a cross-sectional view schematically showing silver-containing particles according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing silver-containing particles according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view that illustrates a silver-containing particle according to a third embodiment of the present invention.

The details of the present invention are explained below.

(Silver-containing particles)
The silver-containing particles according to the present invention include base particles different from metal particles and metal parts disposed on the surface of the base particles, and the metal parts contain silver. The silver-containing particles according to the present invention are composite particles including the base particle and the metal part. In the silver-containing particles according to the present invention, the total amount of outgas of 5 mg of the base particles is 20,000 ppm or less, as measured by the following measuring method.

Method of measuring the total amount of outgassing from 5 mg of base particles: Prepare two samples, 5 mg of the base particles and toluene of a known concentration. Using a thermal desorption device, heat the sample at 250°C for 10 minutes while passing helium gas at a flow rate of 20 mL/min, and adsorb and collect the generated components in a glass tube filled with an adsorbent. While passing helium gas through the glass tube in which the components are collected, heat the glass tube in which the components are collected at 350°C for 40 minutes, and introduce the components desorbed from the adsorbent directly into a gas chromatograph mass spectrometer and analyze it. The peak area value of each component detected when 5 mg of the base particles is used as the sample is compared with the peak area value detected when toluene of the known concentration is used as the sample to calculate the total amount of outgassing from 5 mg of base particles.

The silver-containing particles according to the present invention have the above-mentioned configuration, so when they are used to join components to be joined, they can suppress the occurrence of voids and increase the reliability of the joint over a long period of time.

The silver-containing particles according to the present invention are mixed with metal atom-containing particles such as silver particles and used as a joining material. In the present invention, the joining material is placed between the members to be joined, and the placed joining material is heated to sinter the silver-containing particles and the metal atom-containing particles, thereby joining the members to be joined. The members to be joined are joined, for example, via a joint formed by a sintered body of the joining material.

Since the silver-containing particles according to the present invention use base particles that are less likely to generate outgas, voids are less likely to occur even when exposed to high temperatures. Furthermore, with the silver-containing particles according to the present invention, the electrical conductivity, heat dissipation, and heat resistance of the bonded portion can be improved, and the elastic modulus of the bonded portion can be lowered. Therefore, with the silver-containing particles according to the present invention, even when parts to be joined having different coefficients of thermal expansion are joined together, cracks in the joint part due to warpage and generation of thermal stress in the parts to be joined, and The occurrence of interfacial peeling at the interface with the bonded portion can be effectively suppressed, and the adhesive force between the bonded portion and the members to be bonded can be increased. The silver-containing particles according to the present invention can be used for a long period of time even when used as a component of a bonding material such as a die attach paste or a heat dissipating member bonding material that undergoes reflow processing or requires large-area bonding. It is possible to improve bonding reliability over a long period of time.

The present invention will be described in detail below with reference to the drawings. Note that different parts in FIG. 1 and the figures described below can be interchanged.

FIG. 1 is a cross-sectional view schematically showing silver-containing particles according to a first embodiment of the present invention.

The silver-containing particle 1 shown in FIG. 1 has a base particle 2 and a metal portion 3. The base particle 2 is different from a metal particle. In the first embodiment, the base particle 2 is a resin particle. The metal portion 3 contains silver. The metal portion 3 is disposed on the surface of the base particle 2. In the first embodiment, the metal portion 3 is in contact with the surface of the base particle 2. The silver-containing particle 1 is a coated particle in which the surface of the base particle 2 is coated with the metal portion 3.

In the silver-containing particle 1, the metal portion 3 is a single metal layer and a silver layer.

Silver-containing particles 1 do not have a core substance, unlike silver-containing particles 1B described below. Silver-containing particles 1 do not have protrusions on the surface. The silver-containing particles 1 are spherical. The metal part 3 has no protrusions on its outer surface.

Figure 2 is a cross-sectional view showing a schematic diagram of a silver-containing particle according to a second embodiment of the present invention.

Silver-containing particles 1A shown in FIG. 2 include base particles 2 and metal parts 3A. The base material particles 2 are different from metal particles. The silver-containing particle 1A includes a first metal part 31A and a second metal part 32A as the metal part 3A. The metal part 3A has a two-layer structure. The metal part 3A as a whole includes a second metal part 32A on the base particle 2 side and a first metal part 31A on the opposite side to the base particle 2 side. In the second embodiment, the first metal portion 31A contains silver. The first metal portion 31A is a silver layer. The first metal part 31A and the second metal part 32A are formed as separate metal parts.

The second metal portion 32A is arranged on the surface of the base particle 2. A second metal part 32A is arranged between the base material particle 2 and the first metal part 31A. The second metal portion 32A is in contact with the base particle 2. The first metal part 31A is in contact with the second metal part 32A. Therefore, the second metal portion 32A is placed on the surface of the base particle 2, and the first metal portion 31A is placed on the surface of the second metal portion 32A.

Silver-containing particles 1A do not have a core substance, unlike silver-containing particles 1B described later. The silver-containing particles 1A do not have protrusions on the surface. The silver-containing particles 1A are spherical. The metal part 3A has no protrusions on its outer surface.

FIG. 3 is a cross-sectional view schematically showing silver-containing particles according to a third embodiment of the present invention.

The silver-containing particle 1B shown in FIG. 3 has a base particle 2, a metal portion 3B, and a plurality of core substances 4. The base particle 2 is different from the metal particle. The silver-containing particle 1B has a first metal portion 31B and a second metal portion 32B as the metal portion 3B. The metal portion 3B has a two-layer structure. The metal portion 3B as a whole has a second metal portion 32B on the base particle 2 side and a first metal portion 31B on the opposite side to the base particle 2 side. In the third embodiment, the first metal portion 31B contains silver. The first metal portion 31B is a silver layer. The first metal portion 31B and the second metal portion 32B are formed as separate metal portions.

The second metal portion 32B is arranged on the surface of the base particle 2. A second metal part 32B is arranged between the base material particle 2 and the first metal part 31B. The second metal portion 32B is in contact with the base material particle 2. The first metal part 31B is in contact with the second metal part 32B. Therefore, the second metal portion 32B is placed on the surface of the base particle 2, and the first metal portion 31B is placed on the surface of the second metal portion 32B.

The silver-containing particle 1B has a plurality of protrusions 1Ba on its outer surface. The metal part 3B has a plurality of protrusions 3Ba on its outer surface. The first metal part 31B has a plurality of protrusions 31Ba on its outer surface. The second metal part 32B has a plurality of protrusions 32Ba on its outer surface. A plurality of core substances 4 are disposed on the surface of the base particle 2. The plurality of core substances 4 are embedded in the metal part 3B. The core substances 4 are disposed inside the protrusions 1Ba, 3Ba, 31Ba, and 32Ba. The metal part 3B covers the plurality of core substances 4. The outer surface of the metal part 3B is raised by the plurality of core substances 4, forming the protrusions 1Ba, 3Ba, 31Ba, and 32Ba.

In the silver-containing particles, the metal part may cover the entire surface of the base particle, or may cover a part of the surface of the base particle. In the silver-containing particles, the metal portion may be a single metal layer or a multilayer metal layer composed of two or more layers. The silver-containing particles may or may not have protrusions on the surface. The silver-containing particles may or may not be spherical.

Details about silver-containing particles are provided below.

<Base particle>
The silver-containing particles comprise substrate particles that are different substrate particles from the metal particles.

The silver-containing particles have a total amount of outgas of 5 mg of the base particles of 20,000 ppm or less, as measured by the following measuring method. The total amount of outgas is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, still more preferably 3,000 ppm or less, particularly preferably 2,000 ppm or less. From the viewpoint of further suppressing the generation of voids and further increasing the bonding reliability over a long period of time, it is preferable that the total amount of outgas is as low as possible. Note that the total amount of outgas may be 1000 ppm or more, 1500 ppm or more, or 2000 ppm or more.

Method for measuring the total amount of outgas from 5 mg of base particles: Two samples are prepared: 5 mg of the above base particles and toluene at a known concentration. Using a thermal desorption device, 5 mg of the above base material particles were heated at 250° C. for 10 minutes while passing helium gas at a flow rate of 20 mL/min, and the adsorbent was filled with the generated component (A). It is adsorbed and collected in a glass tube. While passing helium gas through the glass tube in which the component (A) was collected, the glass tube in which the component (A) was collected was heated at 350° C. for 40 minutes to remove the adsorbent. The components desorbed from the gas are directly introduced into a gas chromatograph mass spectrometer and analyzed. Using a thermal desorption device, while passing helium gas at a flow rate of 20 mL/min, toluene of the above known concentration was heated at 250 °C for 10 minutes, and the adsorbent was filled with the generated component (B). It is adsorbed and collected in a glass tube. While passing helium gas into the glass tube in which the component (B) was collected, the glass tube in which the component (B) was collected was heated at 350° C. for 40 minutes to form an adsorbent. The components desorbed from the gas are directly introduced into a gas chromatograph mass spectrometer and analyzed. The peak area value of each component detected when using 5 mg of the above base material particles and the peak area value detected when using toluene of the above known concentration were compared, and the outgas of 5 mg of base material particles was compared. Calculate the total amount.

The known concentration of toluene may be 5 mg of toluene.

More specifically, the total amount of outgas from 5 mg of the base particles is measured as follows.

A sample (5 mg of substrate particles or toluene of known concentration) is sealed in a sample tube and heated at 250°C for 10 minutes while passing helium gas through the sample tube at a flow rate of 20 mL/min. The components volatilized by heating are adsorbed and collected in a glass tube filled with a collector (e.g., TENAX-TA). While passing helium gas through the glass tube in which the volatilized components are collected, the glass tube is heated at 350°C for 40 minutes. The components desorbed from the adsorbent by heating are directly introduced into a gas chromatograph mass spectrometer (hereinafter, GC/MS) and analyzed (ATD-GC/MS). Examples of equipment used for the above measurements and analysis conditions are as follows:

[ATD-GC/MS]
Thermal desorption device: “TurboMatrix350” manufactured by PerkinElmer
GC: “7890A” manufactured by Agilent Technologies
MS: “JMS-Q1000GCQ” manufactured by JEOL Ltd.
Column: “EQUITY-1 60m x 0.25mm I.D. x 0.25μm” manufactured by SUPELCO

<Conditions of the thermal desorption device>
Heating temperature of sample tube: 250°C
Heating time: 10 minutes Helium gas flow rate: 20 mL/min
Cold trap temperature: 4°C
Desorption temperature and time from the collection tube (glass tube): 350°C and 40 min
Split: inlet; 25 mL/min, outlet; 25 mL/min

<GC/MS conditions>
Carrier gas: helium, contact flow Column flow rate: 1.5mL
Split ratio: 1:30
Initial oven temperature: 40℃
Hold time: 4 minutes Heating rate: 10℃/min
Final temperature: 300℃
Hold time: 10 minutes MS: EI mode, 70eV, transfer line: 250°C, ion source: 230°C

The sum of the peak area values of each component detected when 5 mg of the above-mentioned base particles is used is compared with the peak area value detected when a toluene solution of known concentration (for example, "VOCs Mixed Standard Stock Solution III" manufactured by Kanto Chemical Co., Ltd.) is used. From this, the concentration of the volatile components (outgassing) from 5 mg of base particles is calculated in toluene equivalent. In the present invention, the total amount of outgassing (ppm) from 5 mg of base particles is calculated by the following formula.

Total amount of outgassing (ppm) = [(sum of peak area values of volatile components from base particles) / (peak area value of toluene) x concentration of toluene in toluene solution (μg/g) x amount of toluene solution measured (g)] / weight of base particles

The total amount of outgas may be measured using base particles obtained by peeling the metal portion from the silver-containing particles. The total amount of outgas may be measured using base particles obtained by isolating silver-containing particles from a bonding material such as a paste composition and peeling off the metal part from the isolated silver-containing particles. .

Examples of a method for obtaining base particles by peeling off the metal portion from the silver-containing particles include a method for peeling off the metal portion from the silver-containing particles using nitric acid.

Examples of a method for isolating silver-containing particles from the bonding material include a method in which the bonding material is dissolved with nitric acid or a commercially available cured resin dissolving agent, and the silver-containing particles are extracted and isolated.

Of the total amount of outgas (100% by volume), the amount of outgas derived from siloxane is preferably 20% by volume or less, more preferably 10% by volume or less, and even more preferably 3% by volume or less. From the viewpoint of further suppressing the occurrence of voids and further increasing bonding reliability over a long period of time, the lower the amount of outgas derived from siloxane, the better. Note that, of the total amount of outgas (100% by volume), the amount of outgas derived from siloxane may be 1% by volume or more, 50% by volume or more, or 99% by volume or more.

The material of the base particles is not particularly limited as long as the total amount of outgas is 20,000 ppm or less. The material of the base particles may be an organic material or an inorganic material. Examples of the base material particles formed only from the above-mentioned organic material include resin particles. Examples of the base particles formed only of the above-mentioned inorganic material include inorganic particles other than metal particles. Examples of the base particles formed of both the organic material and the inorganic material include organic-inorganic hybrid particles. The base particles are preferably resin particles, inorganic particles other than metal particles, or organic-inorganic hybrid particles, and more preferably resin particles. In particular, when the base material particles are resin particles, the flexibility of the silver-containing particles can be increased, so thermal stress can be effectively alleviated even when joining objects with different coefficients of thermal expansion are joined. This makes it possible to further improve bonding reliability over a long period of time. From the viewpoint of further suppressing the generation of voids and further increasing the bonding reliability over a long period of time, the base material particles are preferably different from silicone particles. That is, the base material particles are preferably different from both the metal particles and the silicone particles.

The organic materials mentioned above include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polycarbonate, polyamide, phenol formaldehyde resin, and melamine. Formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenolic resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamideimide, Examples include polyetheretherketone, polyethersulfone, bismaleimide, divinylbenzene polymer, and divinylbenzene copolymer. Examples of the divinylbenzene copolymer and the like include divinylbenzene-styrene copolymer and divinylbenzene-(meth)acrylic acid ester copolymer. Since the compression properties of the base particles can be easily controlled within a suitable range, the material of the base particles is a polymer obtained by polymerizing one or more polymerizable monomers having ethylenically unsaturated groups. It is preferable that

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

Examples of the non-crosslinkable monomers include vinyl compounds such as styrene monomers, α-methylstyrene, and chlorostyrene; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; acid vinyl ester compounds 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, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl Examples of suitable (meth)acrylates include alkyl (meth)acrylate compounds such as (meth)acrylate and isobornyl (meth)acrylate; oxygen-containing (meth)acrylate compounds 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)acrylate compounds such as trifluoromethyl (meth)acrylate and pentafluoroethyl (meth)acrylate; α-olefin compounds include olefin compounds such as diisobutylene, isobutylene, linearene, ethylene, and propylene; and conjugated diene compounds include isoprene and butadiene.

Examples of the crosslinkable monomers include vinyl compounds such as vinyl monomers like divinylbenzene, 1,4-divinyloxybutane, and divinylsulfone; (meth)acrylic compounds such as tetramethylolmethane tetra(meth)acrylate, polytetramethylene glycol diacrylate, 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, polyethylene glycol di(meth)acrylate, and polypropylene. Polyfunctional (meth)acrylate compounds such as ethylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; allyl compounds such as triallyl (iso)cyanurate, triallyl trimellitate, diallyl phthalate, diallyl acrylamide, and diallyl ether; silane compounds such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, cyclohexyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltriethylenediamine, and the like. silane alkoxide compounds such as acryloxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, trimethoxysilylstyrene, γ-(meth)acryloxypropyltrimethoxysilane, 1,3-divinyltetramethyldisiloxane, methylphenyldimethoxysilane, and diphenyldimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, dimethoxyethylvinylsilane, diethoxymethylvinylsilane, diethoxyethylvinylsilane, ethylmethyldivinylsilane, methylvinyldimethoxysilane, and ethylvinyldimethoxysilane; Examples of such silane alkoxides include silane alkoxides containing polymerizable double bonds, such as silane, 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 one-end modified silicone oil, both-end silicone oil, and side-chain silicone oil; and carboxyl group-containing monomers, such as (meth)acrylic acid, maleic acid, and maleic anhydride.

The base particles can be obtained by polymerizing the ethylenically unsaturated group-containing polymerizable monomer. The above polymerization method is not particularly limited, and includes known methods such as radical polymerization, ionic polymerization, polycondensation (condensation polymerization, condensation polymerization), addition condensation, living polymerization, and living radical polymerization. Other polymerization methods include suspension polymerization in the presence of a radical polymerization initiator.

The above inorganic materials include silica, alumina, titanium oxide, barium titanate, zirconia, carbon black, silicon carbide, silicon nitride, boron nitride, silicate glass, borosilicate glass, lead glass, soda-lime glass, and alumina silicate glass.

The substrate particles may be organic-inorganic hybrid particles. The substrate particles may be core-shell particles. When the substrate particles are organic-inorganic hybrid particles, examples of the inorganic material of the substrate particles include silica, alumina, titanium oxide, barium titanate, zirconia, and carbon black. The inorganic material is preferably not a metal. The substrate particles formed from silica are not particularly limited, but examples include substrate particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, and then baking the resulting particles as necessary. The organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. The base particle is preferably an organic-inorganic hybrid particle having an organic core and an inorganic shell disposed on the surface of the organic core.

Examples of the organic core material include the organic materials described above.

Examples of the material for the inorganic shell include the inorganic substances mentioned above as the material for the base particle. The material of the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a metal alkoxide into a shell-like material by a sol-gel method on the surface of the core, and then firing the shell-like material. Preferably, the metal alkoxide is a silane alkoxide. The inorganic shell is preferably formed of silane alkoxide.

The base particles are preferably resin particles, more preferably divinylbenzene polymer particles, divinylbenzene copolymer particles, acrylic resin particles, or polyolefin resin particles, and divinylbenzene polymer particles or divinylbenzene copolymer particles, or divinylbenzene copolymer particles, or polyolefin resin particles. More preferably, they are benzene copolymer particles. The material of the base particles is more preferably a divinylbenzene polymer, a divinylbenzene copolymer, an acrylic resin, or a polyolefin resin, and even more preferably a divinylbenzene polymer or a divinylbenzene copolymer. In this case, the total amount of outgas can be well controlled, and the bonding reliability can be improved over a longer period of time.

The particle size of the base particle can be selected taking into consideration the particle size of the silver-containing particles. The particle size of the base particle is preferably 1.0 μm or more, more preferably 2.0 μm or more, and even more preferably 2.5 μm or more, and is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. If the particle size of the base particle is equal to or greater than the lower limit and equal to or less than the upper limit, when a metal portion is formed on the surface of the base particle to obtain silver-containing particles, the generated silver-containing particles are even less likely to aggregate with each other, and even when stress is applied to the metal portion, the metal portion is even more unlikely to peel off from the surface of the base particle.

The particle diameter of the base particles is preferably an average particle diameter, and is preferably a number average particle diameter. The particle diameter of the base particles is obtained by observing 50 arbitrary base particles with an electron microscope or optical microscope, calculating the average value of the particle diameter of each base particle, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each base particle is obtained as a particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary base particles with a circle equivalent diameter is almost equal to the average particle diameter of a sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each base particle is obtained as a particle diameter of a sphere equivalent diameter. The average particle diameter of the base particles is preferably calculated using a particle size distribution measuring device. When the particle diameter of the base particles of the silver-containing particles is measured, it can be measured, for example, as follows.

A silver-containing particle content of 30% by weight is added to "Technovit 4000" manufactured by Kulzer and dispersed to prepare an embedded resin body for inspecting silver-containing particles. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies), a cross section of the silver-containing particles is cut out so as to pass near the center of the silver-containing particles dispersed in the embedded resin body for inspection. Then, using a field emission scanning electron microscope (FE-SEM), 50 silver-containing particles are randomly selected and the base particles of each silver-containing particle are observed. The particle size of the base material particles in each silver-containing particle is measured, and the arithmetic average of these is determined as the particle size of the base material particle.

<Metal parts>
The silver-containing particle includes a metal portion disposed on the surface of the base particle. The metal portion includes silver. The metal portion may include only silver as a metal, or may include silver and a metal other than silver.

The metal part may be formed of one layer or a plurality of layers. The metal part may have a one-layer structure, a two-layer structure, two or more layers, or a three-layer or more structure. You can.

From the viewpoint of exhibiting the effects of the present invention even more effectively, the metal part has a first metal part and a second metal part disposed on the inner surface of the first metal part. It is preferable. In this case, it is preferable that the first metal part contains silver. The first metal portion containing silver is preferably the outermost layer of the silver-containing particles. Only one type of metal contained in the first metal portion and the metal contained in the second metal portion may be used, or two or more types may be used in combination.

The first metal portion may contain only silver, or may contain silver and a metal other than silver. From the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the metal constituting the first metal portion is silver.

The metals constituting the second metal part include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, and germanium. , cadmium, silicon, tungsten, molybdenum, and alloys thereof. Furthermore, examples of the metal constituting the second metal portion include tin-doped indium oxide (ITO) and solder.

From the viewpoint of exhibiting the effects of the present invention even more effectively, the second metal part preferably contains nickel, copper, or an alloy thereof, and more preferably contains nickel or an alloy of nickel. . The metal constituting the second metal part is preferably nickel, copper, or an alloy thereof, and more preferably nickel or an alloy of nickel.

In 100% by weight of the first metal part containing silver, the content of silver is preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, even more preferably 70% by weight or more, even more preferably 90% by weight or more, particularly preferably 95% by weight or more, and most preferably 100% by weight (total amount). The content of silver in 100% by weight of the first metal part containing silver may be 10% by weight or less, 5% by weight or less, or 1% by weight or less.

In 100% by weight of the second metal part containing nickel, the content of nickel is preferably 10% by weight or more, more preferably 50% by weight or more, even more preferably 60% by weight or more, even more preferably 70% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more. In 100% by weight of the second metal part containing nickel, the content of the nickel alloy may be 97% by weight or more, 97.5% by weight or more, 98% by weight or more, or 100% by weight (total amount).

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

The thickness of the metal part is preferably 20 nm or more, more preferably 50 nm or more, and preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. The thickness of the metal part is the thickness of the entire metal part when the metal part is multilayered. When the thickness of the metal part is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained and the silver-containing particles can be prevented from becoming too hard.

The ratio of the thickness of the first metal part to the thickness of the second metal part (thickness of the first metal part/thickness of the second metal part) is preferably 0.15 or more, more preferably 0. .5 or more, more preferably 1.0 or more, preferably 6.0 or less, more preferably 5.0 or less. When the ratio (thickness of the first metal part/thickness of the second metal part) is not less than the above lower limit and not more than the above upper limit, the effects of the present invention can be exhibited even more effectively.

When the metal part is formed of multiple layers, the thickness of the metal part of the outermost layer is preferably 20 nm or more, more preferably 50 nm or more, and preferably 1.0 μm or less, more preferably 0.7 μm or less. When the thickness of the metal part of the outermost layer is equal to or greater than the above lower limit and equal to or less than the above upper limit, the coverage by the metal part of the outermost layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes can be sufficiently low.

The thickness of the metal portion can be measured by observing the cross section of the silver-containing particles using, for example, a transmission electron microscope (TEM). Regarding the thickness of the metal part, it is preferable to calculate the average value of the thickness of five arbitrary metal parts as the thickness of the metal part of one silver-containing particle, and calculate the average value of the thickness of the entire metal part as one piece. It is more preferable to calculate it as the thickness of the metal part of the silver-containing particles. The thickness of the metal part is preferably determined by calculating the average value of the thickness of the metal part of each silver-containing particle for ten arbitrary silver-containing particles.

Out of 100% of the total surface area of the outer surface of the base particle, the surface area of the portion covered with the metal part is preferably 50% or more, more preferably 70% or more, still more preferably 90% or more, particularly preferably It is 99% or more, most preferably 100%.

In the silver-containing particles, the outer surface of the metal portion is preferably surface-treated. In this case, corrosion of the silver-containing particles can be suppressed and the connection resistance between the electrodes can be further lowered. By using the silver-containing particles in which the outer surface of the metal portion is surface-treated, it is possible to easily obtain a particle concatenation body in which the outer surface of the metal portion is surface-treated. Examples of the above-mentioned surface treatment include rust prevention treatment, anti-sulfuration treatment, and discoloration prevention treatment. The outer surface of the metal part may be subjected to one type of surface treatment, or may be subjected to two or more types of surface treatment.

Examples of rust inhibitors, sulfuration inhibitors, and discoloration inhibitors used in rust prevention, sulfurization resistance, and discoloration prevention treatments include nitrogen-containing heterocyclic compounds such as benzotriazole compounds and imidazole compounds, sulfur-containing compounds such as mercaptan compounds, thiazole compounds, and organic disulfide compounds, and phosphorus-containing compounds such as organic phosphoric acid compounds.

From the viewpoint of further improving the reliability of electrical conduction, it is preferable that the outer surface of the metal part is rust-proofed with a compound having an alkyl group with 6 to 22 carbon atoms. The outer surface of the metal part may be rust-proofed with a compound that does not contain phosphorus, or may be rust-proofed with a compound that has an alkyl group with 6 to 22 carbon atoms and does not contain phosphorus. From the viewpoint of further improving the reliability of electrical conduction, it is preferable that the outer surface of the metal part is rust-proofed with an alkyl phosphate compound or an alkyl thiol. The rust-proofing treatment can form an anti-rust film on the outer surface of the metal part.

The anticorrosion film is preferably formed of a compound having an alkyl group having 6 to 22 carbon atoms (hereinafter also referred to as compound A). The outer surface of the metal part is preferably surface-treated with the compound A. When the number of carbon atoms in the alkyl group is 6 or more, it becomes even more difficult for rust to occur in the entire metal part, and in particular, it becomes even more difficult for rust to occur in the metal part formed of nickel. When the number of carbon atoms in the alkyl group is 22 or less, the conductivity of the silver-containing particles and the particle linkage becomes high. From the viewpoint of further increasing the electrical conductivity of the silver-containing particles and the particle connected body, the number of carbon atoms in the alkyl group in the compound A is preferably 16 or less. The alkyl group may have a linear structure or a branched structure. It is preferable that the alkyl group has a linear structure.

The above compound A is not particularly limited as long as it has an alkyl group having 6 to 22 carbon atoms. The above compound A is a phosphoric acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, a phosphorous ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, or an alkyl group having 6 to 22 carbon atoms. It is preferable that the alkoxysilane has the following properties. The above compound A is preferably an alkylthiol having an alkyl group having 6 to 22 carbon atoms or a dialkyl disulfide having an alkyl group having 6 to 22 carbon atoms. That is, the compound A having an alkyl group having 6 to 22 carbon atoms is preferably a phosphoric acid ester or a salt thereof, a phosphorous acid ester or a salt thereof, an alkoxysilane, an alkylthiol, or a dialkyl disulfide. By using these preferred compounds A, it is possible to further prevent rust from forming on metal parts. From the viewpoint of making rust even more difficult to form, the compound A is preferably the phosphoric ester or its salt, the phosphorous ester or its salt, or an alkylthiol, and the phosphoric ester or its salt, Alternatively, it is more preferably a phosphite or a salt thereof. Only one type of the above compound A may be used, or two or more types may be used in combination.

The compound A preferably has a reactive functional group capable of reacting with the outer surface of the metal part. The compound A preferably has a reactive functional group capable of reacting with an insulating material described below. The rust-preventive film is preferably chemically bonded to the metal part. The rust-preventive film is preferably chemically bonded to the insulating material. It is more preferable that the rust-preventive film is chemically bonded to both the metal part and the insulating material. The presence of the reactive functional group and the chemical bond make it difficult for the rust-preventive film to peel off, and as a result, rust is more unlikely to occur on the metal part, and the insulating material is more unlikely to unintentionally detach from the surfaces of the silver-containing particles and the particle linkages.

Examples of the phosphate ester or salt thereof having an alkyl group having 6 to 22 carbon atoms include hexyl phosphate, heptyl phosphate, monooctyl phosphate, monononyl phosphate, monodecyl phosphate, monoundecyl phosphate, monododecyl phosphate, monotridecyl phosphate, monotetradecyl phosphate, monopentadecyl phosphate, monohexyl ester monosodium salt, monoheptyl phosphate, monooctyl phosphate, monononyl ester monosodium salt, monodecyl phosphate, monoundecyl phosphate, monododecyl phosphate, monotridecyl ester monosodium salt, monotetradecyl phosphate, monopentadecyl ester monosodium salt, etc. Potassium salts of the above phosphate esters may also be used.

Examples of the phosphorous acid ester or salt thereof having an alkyl group having 6 to 22 carbon atoms include hexyl phosphorous acid ester, heptyl phosphorous acid ester, monooctyl phosphorous acid ester, monononyl phosphorous acid ester, monodecyl phosphorous acid ester, monoundecyl phosphorous acid ester, monododecyl phosphorous acid ester, monotridecyl phosphorous acid ester, monotetradecyl phosphorous acid ester, monopentadecyl phosphorous acid ester, monohexyl phosphorous acid ester monosodium salt, monoheptyl phosphorous acid ester monosodium salt, monooctyl phosphorous acid ester monosodium salt, monononyl phosphorous acid ester monosodium salt, monodecyl phosphorous acid ester monosodium salt, monoundecyl phosphorous acid ester monosodium salt, monododecyl phosphorous acid ester monosodium salt, monotridecyl phosphorous acid ester monosodium salt, monotetradecyl phosphorous acid ester monosodium salt, and monopentadecyl phosphorous acid ester monosodium salt. Potassium salts of the above phosphorous acid esters may also be used.

Examples of alkoxysilanes having an alkyl group having 6 to 22 carbon atoms include hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, nonyltrimethoxysilane, nonyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxysilane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, and pentadecyltriethoxysilane.

Examples of the alkyl thiol having an alkyl group having 6 to 22 carbon atoms include hexyl thiol, heptyl thiol, octyl thiol, nonyl thiol, decyl thiol, undecyl thiol, dodecyl thiol, tridecyl thiol, tetradecyl thiol, pentadecyl thiol, and hexadecyl thiol. The alkyl thiol preferably has a thiol group at the end of the alkyl chain.

Examples of the dialkyl disulfide having an alkyl group having 6 to 22 carbon atoms include dihexyl disulfide, diheptyl disulfide, dioctyl disulfide, dinonyl disulfide, didecyl disulfide, diundecyl disulfide, didodecyl disulfide, ditridecyl disulfide, ditetra Examples include decyl disulfide, dipentadecyl disulfide and dihexadecyl disulfide.

From the viewpoint of further improving the reliability of electrical continuity, it is preferable that the outer surface of the metal part is anti-sulfurized with a layer formed using a sulfur-containing compound mainly composed of a sulfide compound or a thiol compound, a benzotriazole compound, or a polyoxyethylene ether surfactant. The anti-sulfurization treatment forms an anti-rust film on the outer surface of the metal part.

Examples of the above sulfide compounds include dihexyl sulfide, diheptyl sulfide, dioctyl sulfide, didecyl sulfide, didodecyl sulfide, ditetradecyl sulfide, dihexadecyl sulfide, dioctadecyl sulfide, etc., which have about 6 to 40 carbon atoms (preferably carbon number Linear or branched dialkyl sulfide (alkyl sulfide) with a carbon number of about 10 to 40; aromatic compounds with about 12 to 30 carbon atoms such as diphenyl sulfide, phenyl-p-tolyl sulfide, and 4,4-thiobisbenzenethiol. Sulfide; Examples include thiodicarboxylic acids such as 3,3'-thiodipropionic acid and 4,4'-thiodibutanoic acid. Particularly preferred are dialkyl sulfides.

Examples of thiol compounds include those having about 4 to 40 carbon atoms (more preferably about 6 to 20 carbon atoms) such as 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-methyl-2-propanethiol, and octadecylthiol. ), linear or branched alkylthiols, and the like. Also included are compounds in which the hydrogen atom bonded to the carbon group of these compounds is substituted with fluorine.

The above benzotriazole compounds include benzotriazole, benzotriazole salts, methylbenzotriazole, carboxybenzotriazole, and benzotriazole derivatives.

A discoloration inhibitor is used for the above-mentioned discoloration prevention treatment. Examples of the discoloration inhibitor include silver discoloration inhibitors. Commercially available silver discoloration inhibitors include "AC-20", "AC-70", and "AC-80" manufactured by Kitaike Sangyo Co., Ltd., "Entech CU-56" manufactured by Meltex Inc., "New Dyne Silver" and "New Dyne Silver S-1" manufactured by Daiwa Kasei Co., Ltd., and "B-1057" and "B-1009NS" manufactured by Chiyoda Chemical Co., Ltd.

<Core substance and protrusions>
The silver-containing particles preferably have protrusions on the outer surface of the metal part. The number of protrusions is preferably multiple. In this case, the silver-containing particles and the metal atom-containing particles can be sintered more effectively in the bonding material.

It is preferable that the silver-containing particles have a plurality of core substances that raise the surface of the metal portion so as to form a plurality of protrusions within the metal portion.

Methods for forming the protrusions include a method in which a core substance is attached to the surface of a base particle, and then a metal part is formed by electroless plating, and a method in which a metal part is formed on the surface of a base particle by electroless plating, and then a core substance is attached, and then a metal part is formed by electroless plating. In addition, the core substance does not have to be used to form the protrusions.

Other methods for forming the protrusions include a method in which a core material is added during the formation of the metal portion on the surface of the base particle. In addition, in order to form protrusions, a metal part is formed on the base material particle by electroless plating without using the above-mentioned core substance, and then plating is deposited in the shape of a protrusion on the surface of the metal part, and further electroless plating is performed. Alternatively, a method of forming the metal portion using the above method may be used.

Methods for attaching a core substance to the surface of a base particle include a method in which a core substance is added to a dispersion of the base particle, and the core substance is accumulated and attached to the surface of the base particle by van der Waals forces, and a method in which a core substance is added to a container containing the base particle, and the core substance is attached to the surface of the base particle by mechanical action such as rotating the container. From the viewpoint of controlling the amount of core substance to be attached, the method for attaching a core substance to the surface of a base particle is preferably a method in which the core substance is accumulated and attached to the surface of the base particle in the dispersion.

Materials constituting the core material include conductive materials and non-conductive materials. Examples of the conductive materials include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of the conductive polymers include polyacetylene. Examples of the non-conductive materials include silica, alumina, titanium oxide, barium titanate, tungsten carbide, and zirconia. From the viewpoint of more effectively removing the oxide film, it is preferable that the core material is hard. From the viewpoint of more effectively lowering the connection resistance between the electrodes, it is preferable that the core material is a metal.

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

The shape of the core material is not particularly limited. The shape of the core material is preferably a block. Examples of the core substance include particulate lumps, aggregates of a plurality of microparticles, and irregularly shaped lumps.

The particle size of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, and preferably 0.9 μm or less, more preferably 0.2 μm or less. When the particle size of the core substance is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be lowered even more effectively.

The particle diameter of the core substance is preferably the average particle diameter, and more preferably the number average particle diameter. The particle diameter of the core substance is determined by observing 50 arbitrary core substances with an electron microscope or optical microscope, and calculating the average value of the particle diameter of each core substance, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each core substance is determined as the particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary core substances with a circle equivalent diameter is almost equal to the average particle diameter of the sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each core substance is determined as the particle diameter of a sphere equivalent diameter. The average particle diameter of the core substance is preferably calculated using a particle size distribution measuring device.

From the viewpoint of exhibiting the effects of the present invention even more effectively, the surface area of the portion with the projections is preferably 25% or more, more preferably 30% or more of the 100% total surface area of the outer surface of the metal part. , more preferably 50% or more. The surface area of the portion where the projections are present may be 95% or less, 90% or less, or 80% or less.

The number of protrusions per silver-containing particle is preferably 3 or more, and more preferably 5 or more. There is no particular upper limit on the number of protrusions. The upper limit on the number of protrusions can be appropriately selected taking into consideration the particle size of the silver-containing particles, etc. When the number of protrusions is equal to or greater than the lower limit, the connection resistance between the electrodes can be reduced even more effectively.

The number of protrusions can be calculated by observing any silver-containing particle with an electron microscope or optical microscope. It is preferable to determine the number of protrusions by observing 50 random silver-containing particles with an electron microscope or optical microscope and calculating the average number of protrusions on each silver-containing particle.

The height of the protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, and is preferably 0.9 μm or less, more preferably 0.2 μm or less. If the height of the protrusions is equal to or greater than the lower limit and equal to or less than the upper limit, the connection resistance between the electrodes can be reduced even more effectively.

The height of the protrusion can be calculated by observing the protrusion on any silver-containing particle using an electron microscope or an optical microscope. The height of the protrusions is preferably calculated as the average value of the heights of all protrusions per silver-containing particle as the height of the protrusions of one silver-containing particle. The height of the projections is preferably determined by calculating the average value of the heights of the projections of each silver-containing particle for 50 arbitrary silver-containing particles.

<Other details of silver-containing particles>
The particle size of the silver-containing particles is preferably 1 μm or more, more preferably 2.0 μm or more, even more preferably 2.5 μm or more, and preferably 100 μm or less, more preferably 70 μm or less, and still more preferably 50 μm or less. . When the particle diameter of the silver-containing particles is not less than the above lower limit and not more than the above upper limit, the joining reliability of the members to be joined becomes even higher, and the variation in the distance between the members to be joined becomes further smaller. Furthermore, when the particle size of the silver-containing particles is equal to or larger than the lower limit, the thickness of the joint between the members to be joined can be further increased, and the heat dissipation and joint reliability of the joint can be further improved. It can be further improved. When the particle size of the silver-containing particles is equal to or less than the above upper limit, the distance between the electrodes can be further reduced, and the bonded structure can be made smaller and thinner.

The particle diameter of the silver-containing particles is preferably an average particle diameter, and is preferably a number average particle diameter. The particle diameter of the silver-containing particles is determined, for example, by observing 50 arbitrary silver-containing particles with an electron microscope or optical microscope, and calculating the average value of the particle diameter of each silver-containing particle, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each silver-containing particle is determined as the particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary silver-containing particles with a circle equivalent diameter is almost equal to the average particle diameter of the sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each silver-containing particle is determined as the particle diameter of a sphere equivalent diameter. The average particle diameter of the silver-containing particles is preferably calculated using a particle size distribution measuring device.

The compressive elastic modulus (20% K value) when the silver-containing particles are compressed by 20% at 25° C. is preferably 200 N/mm ² or more, more preferably 500 N/mm ² or more, and preferably 10000 N/mm ² It is more preferably 7000 N/mm ² or less. When the compressive modulus is above the lower limit and below the upper limit, the flexibility of the silver-containing particles can be further increased, and cracks in the joint due to warping of the parts to be joined and generation of thermal stress can be prevented. The occurrence of interfacial peeling at the interface between the member and the joint can be effectively suppressed.

The above compressive elastic modulus (20% K value) can be measured as follows:

Using a micro compression tester, one silver-containing particle is compressed with the smooth indenter end face of a cylinder (diameter 100 μm, made of diamond) at 25°C, compression speed 0.3 mN/sec, and maximum test load 20 mN. . At this time, the load value (N) and compression displacement (mm) are measured. From the obtained measured values, the compressive elastic modulus (20% K value) can be determined by the following formula. As the micro compression tester, "Fisher Scope H-100" manufactured by Fisher Co., etc. is used. It is preferable to calculate the compressive elastic modulus (20% K value) of the silver-containing particles by arithmetic averaging the compressive elastic modulus (20% K value) of 50 arbitrarily selected silver-containing particles.

20% K value (N/mm ² ) = (3/2 ^1/2 )・F・S ^-3/2・R ^-1/2
F: Load value (N) when silver-containing particles are compressed and deformed by 20%
S: Compression displacement (mm) when silver-containing particles are compressed and deformed by 20%
R: radius of silver-containing particles (mm)

The compression modulus described above universally and quantitatively represents the hardness of silver-containing particles. By using the above compressive modulus, the hardness of the silver-containing particles can be expressed quantitatively and uniquely.

In the above silver-containing particles, it is preferable that the sum of the Na ion concentration and the K ion concentration in the aqueous phase of the filtrate is 30 μg/g or less, and the Cl ion concentration in the aqueous phase of the filtrate is 60 μg/g or less, as measured by the method for measuring the ion concentration in the aqueous phase of the filtrate described below. In this case, ion migration can be effectively prevented, and the environmental load can be reduced.

Method for measuring the ion concentration in the aqueous phase of the filtrate: 1 g of silver-containing particles and 10 mL of ion-exchanged water with a resistivity of 18 MΩ are placed in a sealable container, and the container is then sealed. The sealed container is heated in an oven at 121°C for 24 hours. The liquid contained in the container after heating is filtered through a membrane filter with a pore size of 0.1 μm. The Na ion concentration and K ion concentration in the aqueous phase of the obtained filtrate are measured using an ICP emission spectrometer. The Cl ion concentration in the aqueous phase of the obtained filtrate is measured using an ion chromatograph.

The silver-containing particles and ion-exchanged water may be housed in a sealable container after mixing, or may be mixed within a sealable container. Commercially available products of the above-mentioned sealable container include high-pressure reaction decomposition container HU-25 (manufactured by San-Ai Kagaku Co., Ltd.). 1 g of silver-containing particles and 10 mL of ion-exchanged water having a specific resistance of 18 MΩ can be completely sealed using a high-pressure reaction decomposition vessel HU-25 (manufactured by San-Ai Kagaku Co., Ltd.).

The sum of the Na ion concentration and K ion concentration in the aqueous phase of the filtrate is preferably 30 μg/g or less, more preferably 10 μg/g or less, even more preferably 1 μg/g or less, and particularly preferably 0.1 μg/g. g or less. When the sum of the Na ion concentration and K ion concentration is below the upper limit, it is possible to suppress the deterioration of the semiconductor element, to prevent ion migration even more effectively, and to further reduce the environmental burden. This can be further reduced.

The Cl ion concentration in the aqueous phase of the filtrate is preferably 60 μg/g or less, more preferably 10 μg/g or less, even more preferably 1 μg/g or less, particularly preferably 0.1 μg/g or less. When the Cl ion concentration is below the upper limit, deterioration of the semiconductor element can be suppressed, ion migration can be prevented even more effectively, and the environmental load can be further reduced. .

The silver-containing particles are preferably used by mixing with a composition containing metal atom-containing particles. The silver-containing particles are preferably used to obtain a paste-like composition containing the silver-containing particles and metal atom-containing particles, and are preferably used to obtain a paste-like composition containing the silver-containing particles and a binder. The silver-containing particles are more preferably used to obtain a paste-like composition containing the silver-containing particles, metal atom-containing particles, and a binder. The paste-like composition is preferably a bonding material. The silver-containing particles are preferably used by sintering with the metal atom-containing particles.

The silver-containing particles may be used as spacers.

The shape of the silver-containing particles is not particularly limited. The shape of the silver-containing particles may be spherical, may be a shape other than spherical, or may be flat or the like.

The silver-containing particles may or may not have an insulating material disposed on the outer surface of the metal part. It is preferable that the silver-containing particles do not have an insulating material disposed on the outer surface of the metal part.

(Paste-like composition)
The paste-like composition includes the above-mentioned silver-containing particles. The paste-like composition preferably includes the silver-containing particles and metal atom-containing particles, preferably includes the silver-containing particles and a binder, and preferably includes the silver-containing particles, metal atom-containing particles, and a binder. The paste-like composition is preferably a bonding material. The paste-like composition is preferably used after sintering. The paste-like composition is preferably a transitional liquid phase sintering type bonding material. The paste-like composition can be sintered to obtain a sintered body.

In this specification, pasty means fluid.

The viscosity of the pasty composition at 25°C is preferably 5.0 Pa·s or more, more preferably 20 Pa·s or more, preferably 500 Pa·s or less, more preferably 250 Pa·s or less, even more preferably It is 100 Pa·s or less, particularly preferably 40 Pa·s or less. When the viscosity at 25° C. of the paste composition is at least the above lower limit and below the above upper limit, bonding reliability can be further effectively improved. The above viscosity can be adjusted as appropriate depending on the types and amounts of the ingredients.

The above viscosity can be measured, for example, using an E-type viscometer (Toki Sangyo Co., Ltd.'s "TVE22L") at 25°C and 5 rpm.

In 100% by weight of the paste-like composition, the content of the silver-containing particles is preferably 0.5% by weight or more, more preferably 1.0% by weight or more, even more preferably 5.0% by weight or more, and is preferably 98% by weight or less, more preferably 95% by weight or less, even more preferably 90% by weight or less. When the content of the silver-containing particles is equal to or more than the lower limit and equal to or less than the upper limit, the bonding reliability can be further improved.

<Metal atom-containing particles>
Preferably, the paste composition includes metal atom-containing particles. The metal atom-containing particles are different from particles that include a base particle different from the metal particle and a metal portion disposed on the surface of the base particle. Examples of the metal atom-containing particles include metal particles and metal compound particles. The metal compound particles include metal atoms and atoms other than the metal atoms. Examples of the metal compound particles include metal oxide particles, metal carbonate particles, metal carboxylate particles, and metal complex particles. The metal compound particles are preferably metal oxide particles. For example, the metal oxide particles are sintered after being turned into metal particles by heating during bonding in the presence of a reducing agent. The metal oxide particles are precursors of metal particles. Examples of the metal carboxylate particles include metal acetate particles.

Examples of the metal constituting the metal atom-containing particles include silver, copper, and gold. The metal constituting the metal atom-containing particles is preferably silver or copper, and particularly preferably silver. Therefore, the metal particles that are the metal atom-containing particles are preferably silver particles or copper particles, more preferably silver particles. The metal oxide particles, which are the metal atom-containing particles, are preferably silver oxide particles or copper oxide particles, more preferably silver oxide particles. When silver particles and silver oxide particles are used, there is little residue after bonding and the volume reduction rate is also very small. Examples of the silver oxide in the silver oxide particles include Ag ₂ O and AgO.

From the viewpoint of exhibiting the effects of the present invention even more effectively, the metal atom-containing particles preferably contain silver particles, and are more preferably silver particles.

The particle diameter of the metal atom-containing particles is preferably 1 nm or more, more preferably 3 nm or more, and preferably 30 μm or less, more preferably 10 μm or less. When the particle diameter of the metal atom-containing particles is equal to or greater than the lower limit and equal to or less than the upper limit, the paste-like composition can be sintered well, and the effects of the present invention can be more effectively achieved.

It is preferable that the metal atom-containing particles include first metal atom-containing particles having a particle diameter of 1 nm or more and less than 500 nm, and second metal atom-containing particles having a particle diameter of 0.5 μm or more and 30 μm or less. In this case, the paste-like composition can be sintered well, and the effects of the present invention can be exerted even more effectively.

The particle diameter of the first metal atom-containing particles is preferably 3 nm or more, and preferably 300 nm or less.

The particle diameter of the second metal atom-containing particles is preferably 1 μm or more, and preferably 15 μm or less.

The particle diameter of the metal atom-containing particles is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the metal atom-containing particles is obtained by observing 50 arbitrary metal atom-containing particles with an electron microscope or optical microscope, and calculating the average value of the particle diameter of each metal atom-containing particle, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each metal atom-containing particle is obtained as the particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary metal atom-containing particles with a circle equivalent diameter is almost equal to the average particle diameter of the sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each metal atom-containing particle is obtained as the particle diameter of a sphere equivalent diameter. The average particle diameter of the metal atom-containing particles is preferably calculated using a particle size distribution measuring device.

The content of the metal atom-containing particles in 100% by weight of the paste composition is preferably 0.5% by weight or more, more preferably 1.0% by weight or more, still more preferably 10% by weight or more, particularly preferably The content is 40% by weight or more, preferably 98% by weight or less, more preferably 90% by weight or less. When the content of the metal atom-containing particles is not less than the above lower limit and not more than the above upper limit, bonding reliability can be further improved.

<Binder>
The paste composition preferably contains a binder. The binder is not particularly limited. Examples of the binder include known insulating resins and organic solvents. Only one kind of the above-mentioned binder may be used, or two or more kinds may be used in combination.

The binder preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. The binder preferably contains a thermoplastic component or a thermosetting component, and preferably contains a thermosetting component. Examples of the curable component include a photocurable component and a thermosetting component. The photocurable component preferably includes a photocurable compound and a photopolymerization initiator. The thermosetting component preferably includes a thermosetting compound and a thermosetting agent. Examples of the binder include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers.

Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. Examples of the curable resin include epoxy resin, urethane resin, silicone resin, polyimide resin, and unsaturated polyester resin. Note that the curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The above-mentioned curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymers include styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated products of styrene-butadiene-styrene block copolymers, and styrene-isoprene block copolymers. - Examples include hydrogenated products of styrene block copolymers. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

The binder may be an organic solvent or may contain an organic solvent. The binder may be a mixture of an organic solvent and the insulating resin.

The organic solvents mentioned above include alcohol compounds such as ethanol and terpineol; ketone compounds such as acetone, methyl ethyl ketone, and cyclohexanone; aromatic hydrocarbon compounds such as toluene, xylene, and tetramethylbenzene; cellosolve, methyl cellosolve, butyl cellosolve, carbitol, and methyl Glycol ether compounds such as carbitol, butyl carbitol, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, tripropylene glycol monomethyl ether; ethyl acetate, butyl acetate , butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, tetraethylene glycol, propylene carbonate, and other ester compounds; octane, Examples include aliphatic hydrocarbon compounds such as decane; lactams such as N-methyl-2-pyrrolidone; nitriles such as phenylacetonitrile; and petroleum solvents such as petroleum ether and naphtha. The above organic solvents may be used alone or in combination of two or more.

In 100% by weight of the paste-like composition, the content of the binder is preferably 1% by weight or more, more preferably 5% by weight or more, even more preferably 10% by weight or more, particularly preferably 15% by weight or more, and is preferably 70% by weight or less, more preferably 50% by weight or less. When the content of the binder is equal to or more than the lower limit and equal to or less than the upper limit, the joining reliability can be further improved.

<Other details of the paste composition>
The paste-like composition may contain components other than these three types: the silver-containing particles, the metal atom-containing particles, and the binder. Examples of the other components mentioned above include curing agents, dispersants, reducing agents, fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, and light stabilizers. , ultraviolet absorbers, lubricants, antistatic agents and flame retardants. Each of the above other components may be used alone or in combination of two or more.

Dispersant:
By using the above-mentioned dispersant, the dispersibility of the above-mentioned silver-containing particles in the paste composition can be improved. The above-mentioned dispersant is not particularly limited and can be appropriately selected depending on the purpose. The above-mentioned dispersants may be used alone or in combination of two or more.

The dispersing agent may be a fatty acid, a fatty acid salt, a surfactant, an organic metal, a protective colloid, or a chelating agent. The fatty acid may be linoleic acid, linosyl acid, oleic acid, stearic acid, propionic acid, lauric acid, palmitic acid, arachidonic acid, caprylic acid, myristic acid, behenic acid, acrylic acid, or a mixture thereof. The dispersing agent is preferably a fatty acid.

When using the above dispersant, the above paste-like composition may be obtained by dry mixing the silver-containing particles and the dispersant, or the above-mentioned paste composition may be obtained by mixing the silver-containing particles and the dispersant together with a solvent. You may get it.

In the paste composition, the content of the dispersant is preferably 0.01 parts by weight or more, preferably 6 parts by weight or less, based on 100 parts by weight of the silver-containing particles.

Reducing agent:
When the metal atom-containing particles are metal oxide particles, the paste composition preferably contains a reducing agent.

Examples of the reducing agent include alcohol compounds (compounds having an alcoholic hydroxyl group), carboxylic acid compounds (compounds having a carboxy group), and amine compounds (compounds having an amino group). The above reducing agents may be used alone or in combination of two or more.

The alcohol compound may be an alkyl alcohol. Specific examples of the alcohol compound 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, icosyl alcohol, and terpineol. The alcohol compound is not limited to a primary alcohol compound, and secondary alcohol compounds, tertiary alcohol compounds, alkanediols, and alcohol compounds having a cyclic structure may also be used. Furthermore, compounds having a large number of alcohol groups, such as ethylene glycol and triethylene glycol, may also be used as the alcohol compound. Compounds such as citric acid, ascorbic acid, and glucose may also be used as the alcohol compound.

Examples of the carboxylic acid compound include alkyl carboxylic acids. Specific examples of the above carboxylic acid compounds 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, and heptadecanic acid. acids such as octadecanoic acid, nonadecanoic acid and icosanoic acid. Further, the above carboxylic acid compound is not limited to a primary carboxylic acid type compound, but also a secondary carboxylic acid type compound, a tertiary carboxylic acid type compound, a dicarboxylic acid, and a carboxyl compound having a cyclic structure.

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

The reducing agent may be an organic substance having an aldehyde group, an ester group, a sulfonyl group, a ketone group, etc., or may be an organic substance such as a carboxylic acid metal salt. While carboxylic acid metal salts are used as precursors of metal particles, they are also used as reducing agents for metal oxide particles because they contain organic substances.

When a reducing agent with a melting point lower than the sintering temperature (bonding temperature) of the metal atom-containing particles is used, the particles tend to aggregate during bonding, making voids more likely to occur at the bonded portion. In contrast, metal carboxylates do not melt when heated during bonding, so the use of metal carboxylates can effectively suppress the occurrence of voids. In addition to metal carboxylates, metal compounds containing organic matter may also be used as reducing agents.

In 100% by weight of the paste-like composition, the content of the reducing agent is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 90% by weight or less, more preferably 70% by weight or less, and even more preferably 50% by weight or less. When the content of the reducing agent is equal to or more than the lower limit and equal to or less than the upper limit, the metal atom-containing particles can be sintered more densely. As a result, the heat dissipation and heat resistance at the joint can be further improved.

The above paste-like composition can be obtained, for example, by mixing and stirring silver-containing particles, metal atom-containing particles, a binder, and other components that are added as necessary.

(Joint structure)
The above paste composition (joining material) can be used to produce a joined structure.

The joining structure includes a first joining target member, a second joining target member, and a joining portion joining the first joining target member and the second joining target member.

In the bonded structure, the bonded portion is preferably formed of a cured product of the bonding material, and more preferably formed of a sintered body of the bonding material.

To form the joint, the joining material is heated. The heating conditions of the joining material can be appropriately changed depending on the composition of the joining material. The heating temperature is preferably 100°C or higher, more preferably 150°C or higher, and preferably 400°C or lower, more preferably 300°C or lower. The heating time is preferably 15 minutes or higher, more preferably 30 minutes or higher, preferably 180 minutes or lower, more preferably 150 minutes or lower. The joining material may be heated in stages. For example, the heating conditions of the joining material may be heating at 40°C to 150°C for 5 minutes to 180 minutes, and then heating at 150°C to 300°C for 5 minutes to 180 minutes.

The bonding material may be heated under pressure or without pressure. The pressure during the pressurization is preferably 0.1 MPa or more and 200 MPa or less. Furthermore, in the method for producing the particle linkage, the heating of the bonding material may be performed in an air atmosphere, a reducing gas atmosphere, or an inert gas atmosphere. good. Examples of the reducing gas include formic acid gas, hydrogen gas, carbon monoxide gas, and hydrocarbon gas. Examples of the inert gas include nitrogen gas, helium gas, argon gas, and forming gas.

The first and second joining target members include a support member and an element. It is preferable that the first joining target member is a support member and the second joining target member is an element. The support member is not particularly limited, and examples thereof include a lead frame, a printed circuit board, an FR4 board, a flexible printed circuit board, a stretchable board, a glass epoxy board and a glass board, various heat dissipation boards, a wired silicon wafer, and a rewiring layer used in a wafer-level CSP. The element is not particularly limited, and examples thereof include active elements such as a semiconductor chip, a transistor, an LED chip, a diode, a light-emitting diode, and a thyristor, and passive elements such as a capacitor, a resistor, a resistor array, a coil, and a switch. It is preferable that the element is a power semiconductor element.

The above-mentioned joint structure preferably constitutes a semiconductor device, and more preferably constitutes a power semiconductor device.

Specific examples of the above semiconductor devices include power modules including diodes, rectifiers, thyristors, MOS gate drivers, power switches, power MOSFETs, IGBTs, Schottky diodes, fast recovery diodes, etc., RFID modules, LED modules, and transmitters. and amplifiers.

Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples. The invention is not limited only to the following examples.

(Example 1)
Preparation of silver-containing particles:
500 g of tetramethylolmethane, 500 g of divinylbenzene, 12 g of benzoyl peroxide, and 8 g of isobutyryl peroxide were mixed and uniformly dissolved to obtain a monomer mixture. 5 kg of a 1% by weight polyvinyl alcohol aqueous solution was prepared and placed in a reaction vessel. The monomer mixture was further added to the reaction vessel and stirred for 2 to 4 hours to adjust the particle size so that the droplets of the monomer mixture had a predetermined particle size. Next, a reaction was carried out in a nitrogen atmosphere at 85° C. for 10 hours to obtain divinylbenzene copolymer resin particles (substrate particles A). After washing the obtained base material particles A several times with hot water, a classification operation was performed. The particle diameter of the obtained base material particles A was 3 μm, and the CV value of the particle diameter was 3.5%.

Next, 10 parts by weight of the base material particles A were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of the palladium catalyst liquid using an ultrasonic disperser, and the solution was filtered to obtain the base material particles A. I took it out. Next, the base particles A were added to 100 parts by weight of a 1% by weight dimethylamine borane solution to activate the surfaces of the base particles A. After thoroughly washing the surface-activated base material particles A with water, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a dispersion liquid.

Next, 1 part by weight of alumina particle slurry (average particle diameter 150 nm) was added to the above dispersion over a period of 3 minutes to obtain a suspension containing base particles A to which the core substance was attached.

As an electroless silver plating solution, a mixed solution containing 15 g/L of silver nitrate, 35 g/L of succinimide, 13 g/L of disodium ethylenediaminetetraacetate, and 20 g/L of hydrazine hydrate was adjusted to pH 8.5 with aqueous ammonia. An adjusted silver plating solution was prepared.

A suspension containing base material particles A was heated to 60° C., and a silver plating solution was gradually dropped thereto to perform electroless silver plating. The dropping rate of the silver plating solution was 10 mL/min, and the dropping time was 30 minutes. Next, the particles are taken out by filtration, washed with water, and dried to form a silver layer (thickness of the entire metal part: 0.15 μm) on the surface of the base material particles, with protrusions on the outer surface. Silver-containing particles were obtained.

(Example 2)
Preparation of silver-containing particles:
In the same manner as in Example 1, a suspension containing base material particles A to which a core substance was attached was obtained.

Nickel plating using a mixed solution containing nickel sulfate 200 g/L, hydrazine hydrate 50 g/L, sodium citrate 30 g/L, thallium nitrate 50 ppm, and bismuth nitrate 20 ppm as an electroless nickel plating solution adjusted to pH 6.5. I prepared the liquid.

A suspension containing base material particles A was heated to 70° C., and a nickel plating solution was gradually dropped thereto to perform electroless nickel plating. The dropping rate of the nickel plating solution was 25 mL/min, and the dropping time was 60 minutes. Next, the particles were taken out by filtration and washed with water to obtain particles in which nickel was arranged on the surface of the base particle A and a metal portion having protrusions on the surface. After thoroughly washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture. Next, silver plating was performed in the same manner as in Example 1, and a nickel layer (second metal part) was disposed on the surface of the base particle, and a silver layer (first metal part) was disposed on the outer surface of the nickel layer. Silver-containing particles were obtained in which silver-containing particles (metal parts) were arranged and had protrusions on the outer surface.

(Example 3)
Silver-containing particles were prepared in the same manner as in Example 2, except that a metal layer containing copper (second metal part) was formed in the following procedure instead of a metal layer containing nickel (second metal part). was created.

In the same manner as in Example 1, a suspension containing base material particles A to which a core substance was attached was obtained. The particles were then placed in a solution containing 20 g/L of copper sulfate and 30 g/L of ethylenediaminetetraacetic acid to obtain a particle mixture.

As an electroless copper plating solution, a mixed solution containing 100 g/L of copper sulfate, 75 g/L of disodium ethylenediaminetetraacetate, 50 g/L of sodium gluconate, and 50 g/L of formaldehyde was adjusted to pH 10.5 with ammonia. A plating solution was prepared.

A suspension containing base material particles A was heated to 50° C., and a copper plating solution was gradually dropped thereto to perform electroless copper plating. The dropping rate of the copper plating solution was 30 mL/min, and the dropping time was 30 minutes. Next, the particles were taken out by filtration and washed with water to obtain particles in which copper was arranged on the surface of the base particle A and had a metal part having protrusions on the surface. After thoroughly washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture. Next, silver plating was performed in the same manner as in Example 1, so that a copper layer (second metal part) was disposed on the surface of the base particle, and a silver layer (first metal part) was disposed on the outer surface of the copper layer. Silver-containing particles were obtained in which silver-containing particles (metal parts) were arranged and had protrusions on the outer surface.

(Example 4)
The procedure was the same as in Example 2, except that instead of the metal layer containing nickel (second metal part), a metal layer containing a copper-nickel-boron alloy (second metal part) was formed in the following procedure. Thus, silver-containing particles were produced.

In the same manner as in Example 1, a suspension containing base material particles A to which a core substance was attached was obtained.

An electroless copper-nickel-boron alloy plating solution was prepared by adjusting the pH of a mixture containing 50 g/L copper sulfate, 50 g/L nickel sulfate, 30 g/L dimethylamine borane, 10 ppm bismuth nitrate, and 30 g/L trisodium citrate with sodium hydroxide to 6.

A suspension containing base material particles A was heated to 50° C., and a copper-nickel-boron alloy plating solution was gradually dropped thereto to perform electroless copper-nickel-boron plating. The dropping rate of the copper-nickel-boron alloy plating solution was 25 mL/min, and the dropping time was 60 minutes. Next, the particles were taken out by filtration and washed with water to obtain particles in which a copper-nickel-boron alloy was disposed on the surface of the base particle A and a metal portion having protrusions on the surface. After thoroughly washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture. Next, silver plating is performed in the same manner as in Example 1, and a copper-nickel-boron alloy layer (second metal part) is disposed on the surface of the base material particle, and the copper-nickel-boron alloy layer is Silver-containing particles were obtained in which a silver layer (first metal portion) was disposed on the outer surface and had protrusions on the outer surface.

(Example 5)
In the same manner as in Example 2, except that instead of the metal layer containing nickel (second metal part), a metal layer containing a nickel-phosphorous alloy (second metal part) was formed in the following procedure, Silver-containing particles were produced.

In the same manner as in Example 1, a suspension containing base material particles A to which a core substance was attached was obtained.

As an electroless nickel-phosphorus alloy plating solution, a mixed solution 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 adjusted to pH 6.5. An adjusted nickel-phosphorus alloy plating solution was prepared.

The suspension containing the base particle A was heated to 50°C, and the nickel-phosphorus alloy plating solution was gradually dropped therein to perform electroless nickel-phosphorus alloy plating. The dropping speed of the nickel-phosphorus alloy plating solution was 25 mL/min, and the dropping time was 60 minutes. Next, the particles were removed by filtration and washed with water to obtain particles having a metal part with protrusions on the surface of the base particle A, in which the nickel-phosphorus alloy was arranged on the surface. 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. Next, silver plating was performed in the same manner as in Example 1, and silver-containing particles having protrusions on the outer surface were obtained, in which a nickel-phosphorus alloy layer (second metal part) was arranged on the surface of the base particle, and a silver layer (first metal part) was arranged on the outer surface of the nickel-phosphorus alloy layer.

Example 6
Silver-containing particles were prepared in the same manner as in Example 2, except that a metal layer (second metal portion) containing a nickel-boron alloy was formed by the following procedure instead of the metal layer (second metal portion) containing nickel.

In the same manner as in Example 1, a suspension containing base particles A to which a core substance was attached was obtained.

An electroless nickel-boron alloy plating solution was prepared by adjusting the pH of a mixture containing 100 g/L nickel sulfate, 30 g/L dimethylamine borane, 10 ppm bismuth nitrate, and 30 g/L trisodium citrate with sodium hydroxide to 6.

The suspension containing the base particle A was heated to 50°C, and the nickel-boron alloy plating solution was gradually dropped therein to perform electroless nickel-boron alloy plating. The dropping speed of the nickel-boron alloy plating solution (C5) was 25 mL/min, and the dropping time was 60 minutes. Next, the particles were taken out by filtration and washed with water to obtain particles in which the nickel-boron alloy was arranged on the surface of the base particle A and which had a metal part having protrusions on the surface. After thoroughly washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture. Next, silver plating was performed in the same manner as in Example 1 to obtain silver-containing particles in which a nickel-boron alloy layer (second metal part) was arranged on the surface of the base particle, a silver layer (first metal part) was arranged on the outer surface of the nickel-boron alloy layer, and protrusions were formed on the outer surface.

(Example 7)
Silver-containing particles were obtained in the same manner as in Example 2, except that the thickness of the silver layer (first metal part) was changed as shown in the table.

(Example 8)
Except for changing the particle diameter to 1 μm, divinylbenzene copolymer resin particles (base particles B) were obtained in the same manner as in Example 1. Except for using the obtained base particles B and changing the thickness of the silver layer (first metal portion) as shown in the table, silver-containing particles were produced in the same manner as in Example 2.

(Example 9)
Divinylbenzene copolymer resin particles (substrate particles C) were obtained in the same manner as in Example 1, except that the particle diameter was changed to 10 μm. Silver-containing particles were produced in the same manner as in Example 2, except that the obtained base particles C were used and the thickness of the silver layer (first metal part) was changed as shown in the table.

(Example 10)
Divinylbenzene copolymer resin particles (substrate particles D) were obtained in the same manner as in Example 1, except that the particle diameter was changed to 20 μm. Silver-containing particles were produced in the same manner as in Example 2, except that the obtained base particles D were used and the thickness of the silver layer (first metal part) was changed as shown in the table.

(Example 11)
Except for changing the particle diameter to 50 μm, divinylbenzene copolymer resin particles (base particle E) were obtained in the same manner as in Example 1. Except for using the obtained base particle E and changing the thickness of the silver layer (first metal portion) as shown in the table, silver-containing particles were produced in the same manner as in Example 2.

(Examples 12 to 15)
Silver-containing particles were prepared in the same manner as in Example 2, except that the thickness of the silver layer (first metal portion) and the thickness of the nickel layer (second metal portion) were changed as shown in the table.

(Example 16)
Silver-containing particles were prepared in the same manner as in Example 2, except that no core material was used.

(Example 17)
Polystyrene particles with an average particle diameter of 0.8 μm were prepared as seed particles. 2.5 g of the polystyrene particles, 500 g of ion-exchanged water, and 100 g of a 5% by weight aqueous solution of polyvinyl alcohol were mixed and dispersed by ultrasonic waves, and then added to a separable flask and stirred uniformly.

In addition, 3.8 g of benzoyl peroxide (Niper BW, manufactured by NOF Corp.), 2.5 g of isobutyryl peroxide, 30 g of triethanolamine lauryl sulfate, and 260 g of N,N-dimethylformamide were added to 1100 g of ion-exchanged water to prepare an emulsion.

Furthermore, a mixture of 129.4 g of 1,4-butanediol diacrylate, 17.6 g of 4-hydroxybutyl acrylate, 26.6 g of CH ₂ CHCOO(C ₄ H ₈ O) ₂ COCHCH, and 26.4 g of HO(C ₄ H ₈ O) ₄ COCHCH was prepared as monomers.

The monomer and the emulsion were further added to the separable flask to which the polystyrene particles were added as seed particles, and the mixture was stirred for 12 hours to allow the seed particles to absorb the monomer. 500 g of a 5 wt % aqueous solution of polyvinyl alcohol was then added, and the reaction was carried out for 9 hours to obtain acrylic resin particles (base particles F). The particle diameter of the obtained base particles F was 3 μm, and the CV value of the particle diameter was 2.7%. Silver-containing particles were produced in the same manner as in Example 2, except that the obtained base particles F were used.

(Example 18)
In a reaction vessel equipped with a thermometer, a stirrer, and a cooling tube, 15 parts by weight of bisphenol A type epoxy resin (DIC Corporation "EXA-850-CRP"), 7.5 parts by weight of polyvinylpyrrolidone as a dispersion stabilizer, and 250 parts by weight of ethanol were added and uniformly dissolved by stirring at 68 ° C. for 1 hour. Next, 4.25 parts by weight of 4,4'-diaminodiphenylmethane and 35 parts by weight of ethanol were added and uniformly dissolved, and then added to the reaction vessel and reacted under conditions of 80 ° C. and 20 hours to obtain a reaction product. The obtained reaction product was washed and then classified. Next, it was heated in an oven at 250 ° C. for 1 hour to obtain epoxy resin particles (base particle G). The particle diameter of the obtained base particle G was 3 μm, and the CV value of the particle diameter was 5.1%. Except for using the obtained base particle G, silver-containing particles were produced in the same manner as in Example 2.

(Comparative example 1)
Silver-containing particles were produced in the same manner as in Example 1, except that silicone particles (KMP-600, manufactured by Shin-Etsu Chemical Co., Ltd., particle size 3 μm) were used as the base particles.

(Comparative example 2)
Silver-containing particles were produced in the same manner as in Example 2, except that silicone particles (KMP-600, manufactured by Shin-Etsu Chemical Co., Ltd., particle size 3 μm) were used as the base particles.

(Comparative example 3)
Except that silicone particles (KMP-601 manufactured by Shin-Etsu Chemical Co., Ltd., particle size 10 μm) were used as the base particles, and the thickness of the first metal layer was changed as shown in Table 1. Silver-containing particles were produced in the same manner as in Example 2.

(Comparative Example 4)
Silver-containing particles were prepared in the same manner as in Example 2, except that silicone particles ("KMP-602" manufactured by Shin-Etsu Chemical Co., Ltd., particle diameter 20 μm) were used as the base particles and the thickness of the first metal layer was changed as shown in Table 1.

(Comparative Example 5)
Silver-containing particles were prepared in the same manner as in Example 2, except that silicone particles ("KMP-602" manufactured by Shin-Etsu Chemical Co., Ltd., particle diameter 50 μm) were used as the base particles and the thickness of the first metal layer was changed as shown in Table 1.

(evaluation)
(1) Particle diameter of base material particles Regarding the obtained base material particles, the particle diameter of approximately 100,000 base material particles was measured using a particle size distribution measuring device (“Multisizer 4” manufactured by Beckman Coulter), and the average The value was taken as the particle diameter of the base material particles.

(2) Thickness of Metal Part The thickness of the metal part was measured by observing the cross section of the obtained silver-containing particle using a transmission electron microscope (TEM) ("JEM2100" manufactured by JEOL Ltd.). The average value of the thicknesses of five arbitrary metal parts was calculated as the thickness of the metal part of one silver-containing particle. Next, the thicknesses of the metal parts of ten arbitrary silver-containing particles were calculated, and the average value was taken as the thickness of the metal part.

In addition, from the results obtained, the ratio of the thickness of the first metal part to the thickness of the second metal part (thickness of the first metal part/thickness of the second metal part) was calculated.

(3) Total amount of outgas Using 5 mg of base particles, measurement was performed by the method described above, and the total amount of outgas for 5 mg of base particles was calculated. Note that the following device was used for the measurement. Furthermore, TENAX-TA was used as an adsorbent. Further, as a toluene solution with a known concentration, "VOCs mixed standard stock solution III" manufactured by Kanto Kagaku Co., Ltd. was used.

[ATD-GC/MS]
Thermal desorption device: PerkinElmer "TurboMatrix350"
GC: Agilent Technologies "7890A"
MS: "JMS-Q1000GCQ" manufactured by JEOL Ltd.
Column: SUPELCO "EQUITY-1 60 m x 0.25 mm I.D. x 0.25 μm"

(4) Measurement of ion concentration in the aqueous phase of the filtrate 1 g of the obtained silver-containing particles and 10 mL of ion-exchanged water with a specific resistance of 18 MΩ were mixed, After the container was placed in a container (manufactured by Kasei Corporation), the container was completely sealed. The sealed container was heated in an oven at 121° C. for 24 hours. After heating, the liquid contained in the container was filtered using a membrane filter with a pore size of 0.1 μm (“Membrane Filter T010A013A” manufactured by Advantech).

Using an ICP emission spectrometer, the Na ion concentration and K ion concentration in the aqueous phase of the obtained filtrate were measured, and the total of the Na ion concentration and K ion concentration was calculated. Further, the Cl ion concentration in the aqueous phase of the obtained filtrate was measured using an ion chromatograph.

(5) Evaluation of Bonded Structure (5-1) Preparation of Paste Composition The following materials were prepared.

Silver particles A (silver nanoparticles, “Mdot” manufactured by Mitsuboshi Belting Co., Ltd.) with a particle size of 10 nm
Silver particles B with a particle size of 4 μm (silver powder, "AgC-A" manufactured by DOWA)
Epoxy resin (Mitsubishi Chemical “1031s”)
Hardening agent (Shikoku Kasei “2E4MZ-A”)

Silver particles A, silver particles B, epoxy resin, and a curing agent were mixed. The obtained silver-containing particles were added to this mixture, and then the mixture was stirred and mixed using a planetary mixer to obtain a paste-like composition (bonding material) having the following composition.

[Blend composition of paste composition]
Silver particles A: 65% by weight
Silver particle B: 5% by weight
Epoxy resin: 15% by weight
Silver-containing particles: 14% by weight
Hardening agent: 1% by weight
Total: 100% by weight

(5-2) Preparation of Joined Structure A silver-plated copper plate (2 cm long x 2 cm wide x 1 mm thick) was prepared as a first member to be joined. A semiconductor chip (2 mm long x 2 mm wide) was prepared as a second member to be joined.

Using a metal mask (opening size: length 2.5 mm × width 2.5 mm × height 40 μm), the obtained paste composition (bonding material) was applied onto a silver-plated copper plate to form a bonding material layer. A semiconductor chip was then laminated onto the bonding material layer to obtain a laminate. The obtained laminate was heated at 120°C for 30 minutes, and then heated at 200°C for 60 minutes to sinter the silver particles A, silver particles B, and silver-containing particles contained in the bonding material to form a bond, and the silver-plated copper plate and the semiconductor chip were bonded by the sintered body to obtain a bonded structure.

(5-3) Presence or absence of voids The semiconductor chip portion of the resulting bonded structure was observed using a microfocus X-ray device (Ohm 90, manufactured by Pony Industries Co., Ltd.) to confirm the presence or absence of voids. The voids were evaluated according to the following criteria.

[Void judgment criteria]
○: There are no voids ×1: There are voids with a maximum diameter of less than 300 μm ×2: There are voids with a maximum diameter of 300 μm or more and less than 500 μm ×3: There are voids with a maximum diameter of 500 μm or more

(5-4) Bonding reliability test (die shear strength)
The resulting bonded structure was subjected to a temperature cycle test (TCT test) under the following conditions.

[TCT test conditions]
The bonded structure was held at −50° C. for 30 minutes and then held at 125° C. for 30 minutes, which constituted one cycle. This cycle was repeated 1000 times.

The die shear strength of the bonded structures before and after the TCT test was measured using a universal bond tester (Nordson's "Dage 4000") at a measurement speed of 100 μm/s and a measurement height of 100 μm.

The rate of decrease in die shear strength was calculated from the obtained die shear strength using the following formula.

Reduction rate of die shear strength (%) = [(Die shear strength after TCT test/Die shear strength before TCT test) x 100] - 100

The composition and results of the silver-containing particles are shown in Tables 1 and 2 below.

1, 1A, 1B...Silver-containing particle 1Ba...Protrusion 2...Base material particle 3, 3A, 3B...Metal part 3Ba...Protrusion 4...Core substance 31A, 31B...First metal part 31Ba...Protrusion 32A, 32B...Second Metal part 32Ba...protrusion

Claims (15)

base material particles different from metal particles,
a metal part disposed on the surface of the base particle,
the metal part contains silver,
Silver-containing particles, wherein the total amount of outgas of 5 mg of the base particles is 20,000 ppm or less as measured by the following measuring method.
Method for measuring the total amount of outgas from 5 mg of base particles: Two samples are prepared: 5 mg of the base particles and toluene at a known concentration. Using a thermal desorption device, the sample was heated at 250°C for 10 minutes while passing helium gas at a flow rate of 20 mL/min, and the generated components were adsorbed into a glass tube filled with an adsorbent. Collect. While helium gas is passed through the glass tube in which the components have been collected, the glass tube in which the components have been collected is heated at 350° C. for 40 minutes to remove the components desorbed from the adsorbent. Directly introduced into a gas chromatograph mass spectrometer and analyzed. The peak area value of each component detected when using 5 mg of the base material particles as the sample and the peak area value detected when toluene of the known concentration was used as the sample were compared, and the base material was determined. Calculate the total amount of outgas for 5 mg of material particles. The metal part has a first metal part and a second metal part disposed on an inner surface of the first metal part,
the first metal part contains silver,
The silver-containing particle according to claim 1, wherein the second metal part contains nickel, copper, or an alloy thereof. The silver-containing particle according to claim 2, wherein the ratio of the thickness of the first metal part to the thickness of the second metal part is 0.15 or more and 6.0 or less. The silver-containing particles according to any one of claims 1 to 3, wherein the metal part has protrusions on its outer surface. The silver-containing particles according to any one of claims 1 to 4, having a particle size of 1 μm or more and 50 μm or less. The silver-containing particles according to any one of claims 1 to 5, having a compressive modulus of elasticity of 500 N/mm2 or ^more and 10,000 N/mm2 or ^less when compressed by 20% at 25°C. The total of the Na ion concentration and K ion concentration in the aqueous phase of the filtrate is 30 μg/g or less, as measured by the following method for measuring the ion concentration in the aqueous phase of the filtrate, and the aqueous phase of the filtrate is The silver-containing particles according to any one of claims 1 to 6, having a Cl ion concentration of 60 μg/g or less.
Method for measuring ion concentration in aqueous phase of filtrate: 1 g of silver-containing particles and 10 mL of ion-exchanged water having a specific resistance of 18 MΩ are placed in a sealable container, and then the container is sealed. Heat the sealed container in an oven at 121° C. for 24 hours. The heated liquid contained in the container is filtered through a membrane filter with a pore size of 0.1 μm. The Na ion concentration and K ion concentration in the aqueous phase of the obtained filtrate are measured using an ICP emission spectrometer. The Cl ion concentration in the aqueous phase of the obtained filtrate is measured using an ion chromatograph. The silver-containing particles according to any one of claims 1 to 7, wherein the amount of outgassing derived from siloxane is 20% by volume or less out of a total amount of outgassing of 100% by volume. The silver-containing particles according to any one of claims 1 to 8, wherein the base particles are different from silicone particles. The silver-containing particles according to any one of claims 1 to 9, which are used in combination with a composition containing metal atom-containing particles. A pasty composition comprising the silver-containing particles according to any one of claims 1 to 10. The paste-like composition according to claim 11, comprising metal atom-containing particles. The paste composition according to claim 12, wherein the metal atom-containing particles include silver particles. The paste-like composition according to any one of claims 11 to 13, comprising a binder. The paste composition according to any one of claims 11 to 14, which is a bonding material.

Images