JP7065576B2 - Fine particles and connecting materials and connecting structures containing the fine particles - Google Patents

Description

The present invention relates to fine particles, a connecting material containing the fine particles, and a connecting structure.

Conventionally, it is known that a connecting member is used for fixing a semiconductor element in a non-insulated semiconductor device (connection structure), which is one of power semiconductor devices (power devices) used for inverters and the like. There is. Such a connecting member can be formed from, for example, a curable adhesive or a sinterable material, and can be one of the electrodes of a semiconductor device depending on the type of the material of the adhesive member. Such connecting members are also used for joining semiconductor elements to each other, joining circuit boards to each other, and the like.

For example, Patent Documents 1 and 2 disclose that a sintered material having an adjusted porosity is used as a connecting member for fixing a semiconductor element. By applying such a sintered material as a connecting member of a semiconductor element, heat dissipation and bonding strength can be ensured. Further, Patent Document 3 also proposes that a composite material containing silicone particles in a thermally conductive metal matrix is used as a bonding member for the purpose of reducing mechanical stress on a semiconductor.

When assembling a semiconductor device or the like, or when replacing a semiconductor element or the like when a semiconductor device fails, a work called rework work is performed. In the rework work, for example, the entire circuit board is heated, the above-mentioned connecting member is melted, and the semiconductor element or the like is reassembled or replaced.

Japanese Unexamined Patent Publication No. 2011-77225 Japanese Unexamined Patent Publication No. 2014-96545 Japanese Unexamined Patent Publication No. 2013-243404

However, if the circuit board is heated for a long time during the rework work, there is a problem that the electronic components mounted on the circuit board are deteriorated by the heating depending on the heat resistant temperature. In addition, in recent power semiconductors and the like, materials such as SiC and GaN are used, and the heating temperature becomes high due to the higher operating temperature range, so that there is a high risk of ignition of circuits and the like, and in terms of safety. Also had a problem. From this point of view, in recent years, there has been a demand for a connecting member that can easily and safely perform rework work by heating in a short time.

The present inventions have been made in view of the above, and the fine particles capable of forming a connecting member capable of easily and safely reworking the connecting structure, the connecting material containing the fine particles, and the connection. The purpose is to provide a structure.

As a result of diligent research to achieve the above object, the present inventor has found that the above object can be achieved by fine particles having a property that the amount of volatile corrosive substances generated under certain heating conditions is a specific amount or more. The present invention has been completed.

That is, the present invention includes, for example, the subjects described in the following sections.
Item 1
In a helium atmosphere, the gas component generated under heating conditions at 250 ° C. for 10 minutes is 4000 ppm or more.
Fine particles, which are corrosive compounds in which the gas component has the property of corroding metals.
Item 2
Item 2. The fine particles according to Item 1, wherein the corrosive compound is at least one selected from the group consisting of silicon compounds and halides.
Item 3
Item 2. The fine particles according to Item 1 or 2, wherein the corrosive compound has a property of corroding at least one selected from the group consisting of copper, gallium silicate, silicon and silicon carbide.
Item 4
Item 2. The fine particles according to any one of Items 1 to 3, wherein the corrosive compound does not have the property of corroding silver.
Item 5
Item 2. The fine particles according to any one of Items 1 to 4, wherein the corrosive compound has a property of vaporizing one or more selected from the group consisting of copper, gallium silicate, silicon and silicon carbide.
Item 6
Item 2. The fine particles according to any one of Items 1 to 5, wherein the surface is coated with a metal.
Item 7
A connecting material containing the fine particles according to any one of Items 1 to 6 and metal particles.
Item 8
Item 7. A connection structure in which a first connection target member and a second connection target member are connected by a connection member containing a cured product of the connection material according to Item 7.
Item 9
Item 8. The connection structure according to Item 8, wherein the shear strength between the first connection target member or the second connection target member and the connection member is reduced by 60% or more after heat treatment at 250 ° C. for 10 minutes.
Item 10
Item 8. A method for reworking a connection structure, comprising a step of heating the connection structure according to Item 8 or 9 to peel off the first connection target member and / or the second connection target member from the connection member.

The fine particles according to the present invention can be applied to a connecting member used for assembling a connecting structure such as a power semiconductor device. In the connection structure provided with the connection member containing the fine particles of the present invention, the operator can easily and safely perform the rework work.

It is a schematic cross-sectional view which shows an example of the connection structure which comprises the connection member containing the fine particle of this invention. It is a schematic diagram which shows the method of forming the laminated body of an Example and a comparative example. It is a schematic diagram of the measuring device for measuring the die shear strength.

Hereinafter, embodiments of the present invention will be described in detail. In addition, in this specification, the expression "contains" and "contains" includes the concepts of "contains", "contains", "substantially consists" and "consists only".

1. 1. Fine Particles The fine particles of the present invention are used as a material for forming a connecting member used for assembling a connecting structure such as a power semiconductor device. The connection member is a member for connecting a pair of connection target members in the connection structure.

FIG. 1 is a schematic cross-sectional view schematically showing an example of a connection structure to which the fine particles of the present invention can be applied. The connection structure of the form of FIG. 1 is a connection connecting the first connection target member 11, the second connection target member 12, and the first connection target member 11 and the second connection target member 12. A member 20 is provided. The connecting member 20 contains the fine particles 10 of the present invention.

The fine particles of the present invention have a gas component of 4000 ppm or more generated under heating conditions of 250 ° C. for 10 minutes in a helium atmosphere, and the gas component is a corrosive compound having a property of corroding a metal. The amount of gas component generated here is a numerical value based on the total mass of the fine particles. Further, the amount of the gas component generated under the heating conditions means the total amount of the gas component (that is, the corrosive compound) generated from the fine particles by heating for the 10 minutes.

In the following, heating fine particles in a helium atmosphere at 250 ° C. for 10 minutes is referred to as a “gas generation test”. The gas generation test can be performed by thermal desorption GC-MS measurement, and can be performed, for example, by using "JMS Q1000 (manufactured by JEOL Ltd.)" equipped with "TurboMatrix 650" manufactured by PerkinElmer.

When the fine particles of the present invention are contained in the connecting member of the connecting structure, the gas component is generated from the fine particles by heat-treating the connecting structure. Since the generated gas component is a corrosive compound as described above, a phenomenon occurs in which the member to be connected is corroded and the adhesive surface of the member to be connected is scraped. As a result, the member to be connected is easily separated from the connecting member. As described above, since the connection structure is in a state where the connection target member and the connection member are easily separated from each other by the heat treatment, the operator can easily perform the rework work of the connection structure. That is, the connection structure including the connection member containing the fine particles of the present invention has a feature of being excellent in reworkability.

Further, since the connection structure including the connection member containing the fine particles of the present invention can peel off the connection target member from the connection member without heating at a high temperature for a long time, the circuit or the like may be ignited due to the high temperature during heating. Easy to prevent. That is, since the connection target member is peeled off from the connection member, the circuit can be cut off at an early stage before ignition occurs, so that the operator can perform the rework work more safely.

The rework work referred to in the present invention refers to, for example, reattachment work of a connection target member in the case of assembling a connection structure, replacement work of the connection target member or the like when a failure of the connection target member occurs, or the like.

In the fine particles of the present invention, the gas component generated in the gas generation test is preferably 4500 ppm or more, more preferably 5000 ppm or more, and more preferably 6000 ppm, in that peeling between the connecting member and the connecting member is likely to occur. The above is particularly preferable. The upper limit of the gas component generated in the gas generation test is, for example, 15,000 ppm.

The gas component generated from the fine particles in the gas generation test is a volatile and corrosive compound having a property of corroding metal. Volatility refers to, for example, the property of easily becoming a gas under the gas generation test conditions. Further, the corrosive compound may be a compound that is a gas at room temperature (for example, 20 ° C.) under atmospheric pressure. For example, the boiling point of the corrosive compound is preferably 50 ° C. or higher. In this case, the corrosive compound is easily encapsulated in the fine particles, and when heated to 250 ° C. or higher, the corrosive compound is easily released to the outside of the fine particles, so that the effect of the present invention is easily exhibited.

The corrosive compound preferably has, for example, a molecular weight of 1000 or less, and in this case, it is excellent in volatility in the gas generation test, and the effect of the present invention is easily exhibited.

The gas component is generated by heating the fine particles. For example, heating of the fine particles causes a redox reaction of a component contained in the fine particles (for example, a matrix component of the fine particles), whereby a corrosive compound which is a gas component is generated from the fine particles.

The "property of corroding metal" (also referred to as metal corrosiveness) in the present invention means a compound capable of exhibiting an action of vaporizing metal. More specifically, the corrosive compound refers to a compound capable of reacting with a metal to ionize the metal and vaporizing (transporting to the outside) the ionized metal.

As described above, the fine particles contain a corrosive compound having metal corrosiveness as a gas component. When the connection structure provided with such fine particles is heated (for example, heated to 250 ° C. or higher), the corrosive compound which is a gas component generated from the fine particles corrodes the member to be connected. As a result, the adhesive surface of the connection target member constituting the connection structure is partially scraped to form a gap, and peeling from the connection member is likely to occur. As a result, the connection structure can have excellent reworkability.

The type of the corrosive compound is not particularly limited as long as it has metal corrosiveness. For example, the corrosive compound can be one or more selected from the group consisting of silicon compounds and halides. In this case, the corrosive compound easily corrodes the metal and can further enhance the reworkability. As a reminder, the halide referred to here refers to a compound other than the silicon compound.

Examples of the silicon compound include the volatile and metal corrosive compounds, for example, a compound containing Si and further bonded with one or more atoms such as hydrogen, oxygen, halogen, carbon, nitrogen and sulfur. Be done. Specific examples of the silicon compound include silane gas (SiH ₄ ), (CH ₃ ) ₃ SiH, (CH ₃ ) ₂ SiH ₂ , (CH ₃ ) SiH ₃ , and alkyltrimethylsilane (for example, 1, 2, 3 or 4 carbon atoms). ), Alkenyltrimethylsilane (eg carbon 1,2,3 or 4), ethynyltrimethylsilane (eg carbon 1,2,3 or 4), silicon nitride, aminosilane, silazane, monoalkoxysilane, dialkoxysilane, tri Examples thereof include alkoxysilane, tetraalkoxysilane, siloxane compound, silyl ester, silanol, monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, monofluorosilane, difluorosilane, trifluorosilane, and tetrafluorosilane. Examples of the siloxane compound include 1,1,3,3-tetramethyldisiloxane and the like.

When the fine particles contain silicon (for example, when they are silicone particles described later), a silicon compound having a Si—H bond is likely to be generated as a gas component. When the fine particles contain silicon, a silicon compound having a Si—H bond may be generated and gasified by the above-mentioned redox reaction. Alternatively, when the fine particles contain silicon, a silicon compound having a Si—H bond may be produced by gasifying the Si—H group retained or bonded in the molecule. When the fine particles have a siloxane bond (Si—O), a silicon compound having a Si—H bond is likely to be generated as a gas component.

From the viewpoint of high volatility and corrosiveness, the silicon compound is preferably a siloxane compound.

The halide has the volatile property and the metal corrosiveness, and contains, for example, a halogen (fluorine, chlorine, bromine, iodine), and is further one or more of hydrogen, oxygen, carbon, nitrogen, sulfur and the like. Examples include compounds in which atoms are bonded. Specific examples of the halide include halogen-substituted hydrocarbons having 1 to 3 carbon atoms, and examples thereof include carbon tetrachloride, chloroform, and dichloromethane.

The corrosive compound preferably has a property of corroding at least one selected from the group consisting of copper, gallium silicate, silicon and silicon carbide. In other words, the corrosive compound preferably has the property of vaporizing one or more selected from the group consisting of copper, gallium titrated, silicon and silicon carbide. In this case, the reworkability can be further improved for a connection structure including a connection target member or the like containing at least one selected from the group consisting of copper, gallium titrated, silicon, and silicon carbide as a material.

Examples of the corrosive compound having a property of easily corroding one or more selected from the group consisting of copper, gallium titrated, silicon and silicon carbide include a siloxane compound and carbon tetrachloride.

In another aspect, the corrosive compound preferably does not have the property of corroding silver. In other words, the corrosive compound preferably does not have the property of vaporizing silver. In this case, as the connecting member in the connecting structure, a sintered body containing silver, which will be described later, can be adopted, and since it does not have the property of corroding silver, the connecting member is corroded during the rework work. It can be suppressed. As a result, the performance of the connection structure formed after the rework is less likely to deteriorate. The corrosive compound may have an action of converting silver into chloride, for example, and even if the silver of the connecting member is changed to chloride during the rework operation, the excellent rework property is maintained. obtain.

Examples of corrosive compounds that do not have the property of corroding silver include siloxane compounds.

It is particularly preferable that the corrosive compound has a property of corroding one or more selected from the group consisting of copper, gallium silicate, silicon and silicon carbide, and does not have a property of corroding silver. Examples of such corrosive compounds include siloxane compounds.

The type of the fine particles of the present invention is not particularly limited as long as a corrosive compound is generated as a gas component in the gas generation test. For example, examples of the fine particles of the present invention include silicone particles and resin particles.

The type of the silicone particles is not particularly limited as long as 4000 ppm or more of the corrosive compound is generated as a gas component in the gas generation test. Silicone particles have, for example, a skeleton composed of SiO units. In this case, an organic group may be bonded to Si or O.

Silicone particles can be obtained, for example, by polymerizing a silicone raw material such as a silicone oligomer having a functional group having a polymerization reactivity. For this polymerization reaction, for example, the same reaction conditions as the polymerization reaction for obtaining known silicone particles can be adopted. In the silicone oligomer, the functional group having a polymerization reactivity is, for example, a functional group having a radical polymerizable property. Specific examples of the radically polymerizable functional group include an acryloyl group (CH ₂ = CH (CO)), a methacryloyl group (CH ₂ = CCH ₃ (CO)), a styryl group, a vinyl group, an allyl group, and the like. Can be mentioned. A silicone compound such as a silicone oligomer having a functional group having a polymerization reactivity can be produced, for example, by a known production process.

When the silicone particles are produced by a polymerization reaction, for example, a corrosive compound can be added to the reaction system in which the polymerization reaction of the silicone raw material is carried out. As a result, corrosive compounds may be contained in the obtained silicone particles. As described above, when silicone particles are obtained using a silicone raw material such as a silicone oligomer having a functional group having a polymerization reactivity, a corrosive compound is added to the polymerization reaction system for obtaining silicone particles from the silicone raw material. be able to. As a result, corrosive compounds may be contained in the obtained silicone particles. Alternatively, a corrosive compound can be added to the reaction system for producing the silicone compound.

The amount of the corrosive compound added is not particularly limited as long as the obtained fine particles generate 4000 ppm or more of the corrosive compound which is a gas component in the gas generation test. For example, the amount of the corrosive compound added can be 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, and 0.7 to 4 parts by mass per 100 parts by mass of the silicone raw material. Is more preferable, and 1 to 3 parts by mass is particularly preferable.

Silicone particles can also be prepared, for example, by a known emulsion polymerization method. Alternatively, the silicone particles can be adjusted by a method of crushing the silicone rubber. The silicone particles may contain an elastomer, a resin, or the like in addition to the matrix composed of the units of SiO.

The type of the resin particles is not particularly limited as long as the corrosive compound is generated at 4000 ppm or more as a gas component in the gas generation test. As a material for forming resin particles, for example, a polyolefin resin such as polyethylene, polypropylene, polystyrene, silicone resin, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; and an acrylic resin such as polymethylmethacrylate and polymethylacrylate; Polyalkylene terephthalate, polysulfone, polycarbonate, polyamide, phenolformaldehyde resin, melamineformaldehyde resin, benzoguanamineformaldehyde resin, ureaformaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, epoxy resin, saturated polyester resin, unsaturated polyester resin, polyphenylene oxide, Examples thereof include polyacetal, polyimide, polyamideimide, polyether ether ketone, polyether sulfone, and urea resin.

The resin particles can also be obtained by polymerizing one or more of various polymerizable monomers having an ethylenically unsaturated group. Examples of the monomer having an ethylenically unsaturated group include a non-crosslinkable monomer and / or a crosslinkable monomer. In the following description, "(meth) acrylic" means one or both of "acrylic" and "methacrylic", and "(meth) acrylate" means one or both of "acrylate" and "methacrylate". means.

Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene, α-methylstyrene, and chlorstyrene as vinyl compounds; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, and 1,4-butanediol divinyl ether. , Cyclohexanedimethanol divinyl ether, vinyl ethers such as diethylene glycol divinyl ether; acid vinyl esters such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate; halogen-containing monomers such as vinyl chloride and vinyl fluoride. Can be mentioned.

Examples of the non-crosslinkable monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate as the (meth) acrylic compound. Alkyl (meth) acrylates such as lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, glycerol ( Oxygen atom-containing (meth) acrylates such as meta) acrylates, polyoxyethylene (meth) acrylates and glycidyl (meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; trifluoromethyl (meth) acrylates, pentafluoro Examples thereof include halogen-containing (meth) acrylates such as ethyl (meth) acrylate.

Examples of the non-crosslinkable monomer include olefins such as diisobutylene, isobutylene, linearene, ethylene and propylene as vinyl compounds and α-olefin compounds; and isoprene and butadiene as conjugated diene compounds.

Examples of the crosslinkable monomer include vinyl-based monomers such as divinylbenzene, 1,4-dibinyloxybutane, and divinyl sulfone as vinyl compounds.

Examples of the crosslinkable monomer include tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, and trimethylolpropanetri (meth) acrylic compounds. Meta) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) Examples thereof include polyfunctional (meth) acrylates such as propylene glycol di (meth) acrylate, (poly) tetramethylene glycol di (meth) acrylate, and 1,4-butanediol di (meth) acrylate.

Examples of the crosslinkable monomer include triallyl (iso) cyanurate, triallyl trimellitate, diallyl phthalate, diallyl acrylamide, diallyl ether and the like as the allyl compound.

Examples of the crosslinkable monomer include tetramethoxysilane, tetraethoxysilane, triethylsilane, t-butyldimethylsilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxy as silicone compounds. Silane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, cyclohexyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxy Silane alkoxides such as silane, diisopropyldimethoxysilane, trimethoxysilylstyrene, γ- (meth) acryloxipropyltrimethoxysilane, 1,3-divinyltetramethyldisiloxane, methylphenyldimethoxysilane, diphenyldimethoxysilane; vinyltrimethoxy; Silane, vinyltriethoxysilane, dimethoxydimethylvinylcisilane, dimethoxyethylvinylsilane, diethoxymethylvinylsilane, diethoxyethylvinylsilane, ethylmethyldivinylsilane, methylvinyldimethoxysilane, ethylvinyldimethoxysilane, methylvinyldiethoxysilane, ethyl Vinyl diethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3 -A silane alkoxide containing a polymerizable double bond such as acryloxypropyltrimethoxysilane; a cyclic siloxane such as decamethylcyclopentasiloxane; modification of one-ended silicone oil, two-ended silicone oil, side-chain silicone oil, etc. (reactivity) ) Silicone oil; examples thereof include carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride.

The crosslinkable and non-crosslinkable monomers are not limited to the monomers listed above, and may be other polymerizable monomers, for example, known polymerizable monomers.

Examples of the polymerization method of a polymerizable single amount having an ethylenically unsaturated group include a method of suspend polymerization in the presence of a radical polymerization initiator and a monomer using a non-crosslinked seed particle together with a radical polymerization initiator. A method of swelling and polymerizing (so-called seed polymerization method) and the like can be mentioned. The conditions of these polymerization methods are not particularly limited and can be known conditions. The corrosive compound can be added to a polymerizable single amount having an ethylenically unsaturated group. Thereby, the obtained resin particles can contain a corrosive compound.

The shape of the fine particles is not particularly limited and may be spherical, for example. The sphere may be either a true sphere or a non-true sphere. When the fine particles are non-true spheres, they can have an elliptical shape, an irregular shape, or the like.

The average particle size of the fine particles is not particularly limited, and may be, for example, 0.05 μm or more and 300 μm or less. The average particle size of the fine particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, and preferably 200 μm or less, more preferably 160 μm or less, still more preferably 80 μm or less, and particularly preferably 30 μm or less. ..

The average particle diameter of the fine particles means the diameter when the shape is a true sphere, and means the average value of the maximum diameter and the minimum diameter when the shape is other than the true sphere. The average particle size of the fine particles means an average value obtained by observing the substrate particles with a scanning electron microscope and measuring the particle size of 50 randomly selected substrate particles with a nogis. The average particle diameter when the base particles are coated with metal as described later includes the coating layer.

The fine particles preferably have a thermal decomposition temperature of 200 ° C. or higher, and in this case, the thermal decomposition of the fine particles is likely to be suppressed when the connecting member of the connecting structure is formed as described later. The thermal decomposition temperature of the fine particles is preferably 220 ° C. or higher, more preferably 250 ° C. or higher, still more preferably 300 ° C. or higher. When the fine particles are coated with a metal described later, the temperature at which the fine particles and the metal are thermally decomposed first is defined as the thermal decomposition temperature of the fine particles.

It is also preferable that the surface of the fine particles is coated with a metal. When the connecting member contains fine particles whose surface is coated with metal as described above, even if stress is applied to the connecting member, the effect of relaxing the stress, that is, the stress relaxation effect can be exhibited. Therefore, for example, even if a load is applied to the connection structure during the rework work, it is possible to suppress warpage or deformation of the connection structure.

Metals that can coat fine particles include, for example, gold, silver, tin, copper, germanium, indium, palladium, tellurium, thallium, bismuth, zinc, arsenic, selenium, iron, lead, ruthenium, aluminum, cobalt, titanium, antimony, etc. Examples thereof include cadmium, silicon, nickel, chromium, platinum, rhodium and the like. The metal may be only one kind of each of these metals, or may contain two or more kinds. Further, the metal may be an alloy of two or more kinds of metals among the respective metals listed above.

When the fine particles are coated with metal, the metal layer may be a single layer or a plurality of layers.

When the fine particles are coated with a metal, the thickness of the metal is preferably 0.5 nm or more, more preferably 10 nm or more, preferably 10 μm or less, more preferably 1 μm or less, still more preferably 500 nm or less, and particularly preferably. It is 300 nm or less.

The method of coating the surface of the fine particles with metal is not particularly limited. For example, by a known method such as a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating a metal powder or a paste containing a metal powder and a binder on the surface of a base particle, a fine particle surface is used. Can be coated with metal.

The metal covering the fine particles may have a plurality of protrusions. Such protrusions can also be formed, for example, by a known method. The shape and size of the protrusions are not particularly limited. It can be the same as known.

The fine particles of the present invention can be used as a connecting member for assembling a connecting structure, and can improve the reworkability of the connecting structure and the safety during the reworking work. Therefore, the fine particles of the present invention can be suitably used as a material for a connecting member of a connecting structure.

2. 2. Connection material The connection material contains the fine particles and metal particles. The connecting material is a material that can form the connecting member (see FIG. 1 and the like) by being cured. The connecting material is, for example, a material that is cured by heating and sintering (that is, a sintered material).

The type of metal particles is not particularly limited. For example, metal particles similar to known connecting materials can be used.

The metal particles may be particles of a single metal or particles of a metal compound. The metal compound is a compound containing a metal atom and an atom other than the metal atom.

Specific examples of the metal compound include metal oxides, metal carbonates, metal carboxylates, metal complexes and the like. The metal compound is preferably a metal oxide. For example, the metal oxide is sintered after becoming metal particles by heating at the time of connection in the presence of a reducing agent. The metal oxide is a precursor of metal particles. Examples of the metal carboxylate particles include metal acetate particles.

The metals contained in the metal particles and metal compounds are gold, silver, tin, copper, germanium, indium, palladium, tellurium, tarium, bismuth, zinc, arsenic, selenium and at least one of these metal elements. It is preferable to contain at least one selected from the group consisting of alloys containing. It is more preferable that the metal contained in the metal particles contains at least one selected from the group consisting of gold, silver and copper.

In particular, the metal particles are preferably at least one of silver particles and silver oxide particles. Since these metal particles are materials having a high melting point, they are less likely to be vaporized by the corrosive compound, and since they have a high melting point, they are less likely to be corroded by the corrosive compound. Therefore, when the metal particles are at least one of silver particles and silver oxide particles, deterioration of the connecting member is unlikely to occur in the connecting structure obtained after the rework, and the strength, performance, etc. of the connecting structure even after the rework, etc. Is not easily damaged. Examples of silver oxide include Ag ₂ O and Ag O.

The average particle size of the metal particles is preferably 10 nm or more and 10 μm or less. Further, from the viewpoint of increasing the connection strength of the member to be connected, it is preferable that the metal particles include two or more kinds of metal particles having different average particle diameters. When having two or more kinds of metal particles having different average particle diameters, the average particle diameter of the metal particles having a small average particle diameter is preferably 10 nm or more, and preferably 100 nm or less. The average particle size of the metal particles having a large average particle size is preferably 1 μm or more, and preferably 10 μm or less. The ratio of the blending amount of the metal particles having a small average particle size to the metal particles having a large average particle size is preferably 1/9 or more and 9 or less. The average particle size is obtained by observing the metal particles with a scanning electron microscope and arithmetically averaging the maximum diameters of 50 arbitrarily selected particles in the observed image.

The metal particles are preferably sintered by heating at less than 400 ° C. The temperature at which the metal particles are sintered (sintering temperature) is more preferably 350 ° C. or lower, preferably 300 ° C. or higher. When the temperature at which the metal particles are sintered is below or below the above upper limit, sintering can be performed efficiently, the energy required for sintering can be further reduced, and the environmental load can be reduced. can.

When the metal particles are metal oxide particles, it is preferable that the connecting material contains a reducing agent. Examples of the reducing agent include alcohols (compounds having an alcoholic hydroxyl group), carboxylic acids (compounds having a carboxy group), amines (compounds having an amino group) and the like. Only one kind of the reducing agent may be used, or two or more kinds thereof may be used in combination.

Examples of alcohols include alkyl alcohols. Specific examples of the above alcohols include, for example, ethanol, propanol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, and tetradecyl alcohol. , Pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, nonadecyl alcohol, icosyl alcohol and the like. Further, the alcohols are not limited to the primary alcohol type compound, but a secondary alcohol type compound, a tertiary alcohol type compound, an alkanediol and an alcohol compound having a cyclic structure can also be used. Further, as the alcohols, a compound having a large number of alcohol groups such as ethylene glycol and triethylene glycol may be used. Further, as the alcohols, compounds such as citric acid, ascorbic acid and glucose may be used.

Examples of carboxylic acids include alkylcarboxylic acids and the like. Specific examples of the above carboxylic acids include butanoic acid, pentanoic acid, hexanoic acid, heptanic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid and heptadecanoic acid. , Octadecanoic acid, nonadecanic acid, icosanoic acid and the like. Further, the carboxylic acids are not limited to the primary carboxylic acid type compound, but a secondary carboxylic acid type compound, a tertiary carboxylic acid type compound, a dicarboxylic acid and a carboxyl compound having a cyclic structure can also be used.

Examples of amines include alkylamines and the like. Specific examples of the above amines include butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, and hexadecylamine. Examples thereof include heptadecylamine, octadecylamine, nonadecilamine and icodecylamine. Moreover, the above-mentioned amines may have a branched structure. Examples of amines having a branched structure include 2-ethylhexylamine and 1,5-dimethylhexylamine. The amines are not limited to primary amine compounds, but 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, or the like, or may be an organic substance such as a carboxylic acid metal salt. While the carboxylic acid metal salt is also used as a precursor for metal particles, it is also used as a reducing agent for metal oxide particles because it contains an organic substance.

The content of the reducing agent is preferably 1 part by mass or more, more preferably 10 parts by mass or more, preferably 1000 parts by mass or less, more preferably 500 parts by mass or less, still more preferably, with respect to 100 parts by mass of the metal particles. Is 100 parts by mass or less. When the content of the reducing agent is at least the above lower limit, the metal particles can be sintered more densely.

If a reducing agent having a melting point lower than the sintering temperature (connection temperature) of the metal particles is used, it tends to aggregate at the time of connection and voids are likely to occur at the connection portion. By using the carboxylic acid metal salt, the carboxylic acid metal salt is not melted by heating at the time of connection, so that the formation of voids can be suppressed. In addition to the carboxylic acid metal salt, a metal compound containing an organic substance may be used as the reducing agent.

The connecting material may contain a resin binder. The resin binder preferably contains a thermoplastic resin or a curable resin, and more preferably contains a curable resin. Examples of the curable resin include a photocurable resin and a thermosetting resin. The photocurable resin preferably contains a photocurable resin and a photopolymerization initiator. The thermosetting resin preferably contains a thermosetting resin and a thermosetting agent. Examples of the resin binder include known vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, elastomers and the like. The resin binder may be used alone or in combination of two or more.

The connecting material may contain a dispersion medium. Examples of the dispersion medium include known solvents and the like.

The connecting material may be adjusted using a known connecting material except that it contains the fine particles. Known connection materials include "CT2700" manufactured by Kyocera Chemicals, "ASP295", "ASP016", "ASP043" manufactured by Heraeus, "LocTITE ABLESTIK SSP2020" manufactured by Henkel, "H9890-6A" manufactured by Namics, and Harima Chemicals. "NH-4000", "NH-225D", "NH-3000D" manufactured by Kaken Tech, "CM-3212", "CR-3520" manufactured by Kaken Tech, "Arconano Silver Paste ANP-1" manufactured by Nippon Superior Co., Ltd., etc. Can be mentioned.

In the connecting material, the content of the metal particles is preferably higher than the content of the fine particles, for example, the content of the metal particles is more preferably 10% by mass or more higher than the content of the fine particles, 20 It is more preferable that the amount is more than% by mass.

In the connecting material, the content of fine particles is preferably 0.1% by mass or more, more preferably 1% by mass or more, preferably 50% by mass or less, and more preferably 20% by mass in 100% by mass of the components excluding the dispersion medium. % Or less, particularly preferably 10% by mass 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, the reworkability is particularly excellent.

In the connecting material, the content of the metal particles in 100% by mass of the component excluding the dispersion medium is preferably 70% by mass or more, more preferably 80% by mass or more, preferably 98% by mass or less, and more preferably 95% by mass. % Or less. When the content of the metal particles is not less than the lower limit and not more than the upper limit, the metal particles can be sintered more precisely.

When the connecting material contains the resin binder, the content of the resin binder is preferably 1% by mass or more, more preferably 5% by mass or more, and preferably 20% by mass in 100% by mass of the component excluding the dispersion medium of the connecting material. % Or less, more preferably 15% by mass or less. When the content of the resin binder is not less than the above lower limit and not more than the above upper limit, the metal particles can be sintered more densely.

The method for producing the connecting material is not particularly limited, and for example, it can be prepared by mixing fine particles and metal particles with a dispersion medium and a resin binder, which are other components, in a predetermined blending amount, if necessary. It can also be prepared by adding fine particles to a commercially available connecting material. As a mixing method, a known method can be widely adopted.

3. 3. Connection structure In the connection structure, the first connection target member and the second connection target member are connected by a connection member containing a cured product of the connection material. As the connection structure, for example, the above-mentioned form of FIG. 1 can be mentioned.

The cured product of the connecting material contained in the connecting member is formed, for example, by sintering the connecting material at a predetermined temperature. That is, the cured product of the connecting material can mean a sintered body of the connecting material. The sintering conditions of the connecting material are not particularly limited, and known sintering conditions can be widely applied.

The connecting member can contain a cured product of the connecting material in an amount of 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and 99% by mass or more based on the total mass of the adhesive member. It is particularly preferable to include it. Further, the adhesive member may be formed only of the connecting material.

In the connecting member, the content of the fine particles is preferably 0.1% by mass or more, more preferably 1% by mass or more, preferably 20% by mass or less, and more preferably 10% by mass or less. Further, in the connecting member, the content of the metal particles is preferably 70% by mass or more, more preferably 80% by mass or more, preferably 98% by mass or less, and more preferably 95% by mass or less.

The connecting member may also contain known particles having the function of controlling the gap. The particles having a function of controlling the gap can serve as a spacer between the first connection target member and the second connection target member.

Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors and diodes, and electronic components such as printed circuit boards, flexible printed circuit boards, glass epoxy boards and circuit boards such as glass substrates. The member to be connected is preferably an electronic component. Further, it is preferable that at least one of the first connection target member and the second connection target member is a semiconductor wafer or a semiconductor chip. That is, the connection structure is preferably a semiconductor device.

The method for manufacturing the connection structure is not particularly limited. As an example of a method for manufacturing a connection structure, a connection material is sandwiched between a first connection target member and a second connection target member, and the first connection target member, the connection material, and the second connection target member are the same. Examples thereof include a method of forming a laminated body laminated in order and heating and pressurizing the laminated body. As a result, the metal particles contained in the laminated body are sintered, an adhesive member in which fine particles are dispersed in the sintered body is formed, and the first connection target member and the second connection target member are connected by the connection member. To. The laminated body can be formed by applying a connecting material to one of the connection target members to form a coating film and superimposing the other connection target member on the coating film surface.

In the connection structure, the shear strength between the first connection target member or the second connection target member and the connection member is preferably reduced by 60% or more after heat treatment at 250 ° C. for 10 minutes. That is, when the connection structure is heat-treated at 250 ° C. for 10 minutes, the shear strength between the first connection target member or the second connection target member and the connection member may decrease by 60% or more before and after the heat treatment. preferable. In this case, one or both of the members to be connected can be easily peeled off by heating, so that the reworkability is further improved. The conditions of the heat treatment here are the same as those of the gas generation test, and the heat treatment is the treatment that is first performed after the connection structure is obtained.

When the connection structure is heat-treated at 250 ° C. for 10 minutes, the shear strength between the first connection target member or the second connection target member and the connection member is preferably 10 MPa or less. In this case, one or both of the members to be connected can be easily peeled off by heating, so that the reworkability is further improved. The conditions of the heat treatment here are the same as those of the gas generation test, and the heat treatment is the first (first) treatment after obtaining the connection structure. The shear strength is more preferably 5 MPa or less, and particularly preferably 3 MPa or less.

4. Method of Reworking the Connection Structure The method of reworking the connection structure includes, for example, a step of heating the connection structure to peel off the first connection target member and / or the second connection target member from the connection member. be able to. By heating the connection structure, the gas component generated from the fine particles contained in the connection member causes corrosion of the connection target member, whereby the connection target member can be separated from the connection member.

The heating conditions for reworking (disassembling) the connection structure are not particularly limited. For example, the heating temperature can be 250 to 400 ° C, preferably 300 to 400 ° C. The heating time can be appropriately set depending on the heating temperature, and can be, for example, 5 to 10 minutes.

According to the rework method of the connection structure of the present invention, the member to be connected can be peeled off from the connection member under simple conditions, so that the reworkability is excellent. Further, since the member to be connected can be separated from the connecting member and disassembled without heating to a high temperature, the circuit can be disconnected before the circuit becomes hot, and it is easy to prevent ignition during rework work. Therefore, according to the method of disassembling the connection structure of the present invention, the reworkability is excellent and the operator can safely perform the rework work.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the embodiments of these Examples.

(Production Example 1; Production of Silicone Particle 1)
1. 1. Preparation of silicone oligomer
In a 100 ml separable flask placed in a warm bath, 1 part by mass of 1,3-divinyltetramethyldisiloxane and 20 parts by mass of a 0.5 mass% p-toluenesulfonic acid aqueous solution were placed. After stirring at 40 ° C. for 1 hour, 0.05 parts by mass of sodium hydrogen carbonate was added. Then, 10 parts by mass of dimethoxymethylphenylsilane, 49 parts by mass of dimethyldimethoxysilane, 0.6 parts by mass of trimethylmethoxysilane, and 3.6 parts by mass of methyltrimethoxysilane were added, and the mixture was stirred for 1 hour. Then, 1.9 parts by mass of a 10 mass% potassium hydroxide aqueous solution was added, the temperature was raised to 85 ° C., and the pressure was reduced with an aspirator while stirring for 10 hours to carry out the reaction. After completion of the reaction, the pressure was returned to normal pressure, the mixture was cooled to 40 ° C., 0.2 part by mass of acetic acid was added, and the mixture was allowed to stand in a separating funnel for 12 hours or more. The lower layer after the two-layer separation was taken out and purified by an evaporator to obtain a silicone oligomer.

2. 2. Preparation of Silicone Particles In 30 parts by mass of the obtained silicone oligomer, 0.5 parts by mass of tert-butyl-2-ethylperoxyhexanoate (polymerization initiator, "Perbutyl O" manufactured by Nichiyu Co., Ltd.) and 1,1,3 parts. , 3-Tetramethyldisiloxane A solution A in which 0.4 parts by mass was dissolved was prepared. In addition, in 150 parts by mass of ion-exchanged water, 0.8 parts by mass of a 40% by mass aqueous solution of triethanolamine lauryl sulfate (embroidery) and 80 parts by mass of polyvinyl alcohol (“Gosenol GH-20” manufactured by Nippon Synthetic Chemical Co., Ltd.) 80% by mass. Aqueous solution B was prepared by mixing with a mass portion. The polyvinyl alcohol used had a degree of polymerization of about 2000 and a degree of saponification of 86.5 to 89 mol%. The solution A is placed in a separable flask placed in a warm bathtub, the aqueous solution B is added, and then a Shirasu Porous Glass (SPG) membrane (pore average diameter of about 1 μm) is used for emulsification. Was done. After emulsification, the temperature was raised to 85 ° C. and polymerization was carried out for 9 hours. The entire amount of the polymerized particles was washed with water by centrifugation and freeze-dried. After drying, the particles were pulverized with a ball mill until the agglomerates of the particles had a desired ratio (average secondary particle diameter / average primary particle diameter) to obtain silicone particles 1 having a particle diameter of 3.0 μm.

(Production Example 2; Production of Silicone Particles 2)
Silicone particles 2 having a particle size of 3.0 μm were prepared by the same method as in Production Example 1 except that 0.4 parts by mass of 1,1,3,3-tetramethyldisiloxane was changed to 0.3 parts by mass. Obtained.

(Production Example 3; Production of Silicone Particles 3)
Silicone particles 3 having a particle diameter of 3.0 μm were prepared by the same method as in Production Example 1 except that 0.4 parts by mass of 1,1,3,3-tetramethyldisiloxane was changed to 0.2 parts by mass. Obtained.

(Production Example 4; Production of Resin Particle 1)
As seed particles, 48 g of polystyrene particles having an average particle diameter of 1.30 μm, 100 g of ion-exchanged water, 342 g of methanol, and 6 g of a 5 wt% aqueous solution of polyvinylpyrrolidone were mixed, dispersed by ultrasonic waves, and then placed in a separable flask. Added. The inside of the separable flask was uniformly stirred to prepare a polystyrene particle suspension.

Further, 100 g of triethylene glycol dimethacrylate, 150 g of 2-ethylhexyl methacrylate, 3 g of a polymerization initiator, 12.5 g of a surfactant, and 980 g of methanol were added to 250 g of ion-exchanged water to prepare an emulsion. The polymerization initiator is 2,2'-azobis (2,4-dimethylvaleronitrile) ("V-65" manufactured by Wako Pure Chemical Industries, Ltd.), and the surfactant is polyoxyethylene styrenated phenyl ether sulfate ammonium salt (No. 1). A 20% aqueous solution of "Hitenol (registered trademark) NF-08" manufactured by Ichiko Pharmaceutical Co., Ltd. was used.

The emulsion was added to the separable flask to which the polystyrene suspension was added, and the mixture was stirred for 8 hours to swell the seed particles.

Then, 60 g of a 10 wt% aqueous solution of polyvinyl alcohol, 0.01 g of 1,1,3,3-tetramethyldisisiloxane and 250 g of ion-exchanged water were added to the separable flask containing the swollen seed particles. Then, stirring was continued at 65 ° C. for 2 hours to obtain resin particles 1 having an average particle diameter of 2.95 μm.

(Production Example 5; Production of Resin Particles 2)
Resin particles (resin particles 2) were obtained by the same method as in Production Example 4 except that 1,1,3,3-tetramethyldisisiloxane was not used.

(Example 1)
100 parts by mass of silver paste (“Arconano silver paste ANP-1” manufactured by Nippon Superior Co., Ltd.) and 1 part by mass of the silicone particles 1 obtained in the production example are kneaded with a spatula so as to disperse well, and a connecting material is used. Was prepared.

As shown in FIG. 2, cylindrical copper (10 mm diameter and 5 mm thickness) is used as the substrate 100, and the connection material is screen-coated on the substrate 100 to form a paste layer 200 (5 mm diameter and 50 μm thickness). It was formed (FIG. 2 (a)). A copper disk chip 101 (5 mm diameter and 2 mm thick) was placed on the paste layer 200 (FIG. 2 (b)). Then, it was dried at 130 ° C. for 90 seconds in a nitrogen or helium atmosphere, and then heated at 300 ° C. for 3 minutes while pressurizing at 5 MPa to sinter the connecting material and cure it. As a result, a laminated body 1 in which two Cu substrates (substrate 100 and chip 101) were connected by a connecting member 20 was obtained.

(Example 2)
A laminate was obtained in the same manner as in Example 1 except that the silicone particles 1 were changed to the silicone particles 2 obtained in Production Example 2.

(Example 3)
A laminate was obtained in the same manner as in Example 1 except that the silicone particles 1 were changed to the resin particles 1 obtained in Production Example 4.

(Comparative Example 1)
A laminate was obtained in the same manner as in Example 1 except that the silicone particles 1 were changed to the silicone particles 3 obtained in Production Example 3.

(Comparative Example 2)
A laminate was obtained in the same manner as in Example 1 except that the silicone particles 1 were changed to the resin particles 2 obtained in Production Example 5.

(Amount of gas generated by fine particles)
The amount of gas component generated in the gas generation test of the fine particles was measured by heat desorption GC-MS measurement. For the measurement, a "JMS Q1000 (manufactured by JEOL Ltd.)" equipped with a "TurboMatrix 650" manufactured by PerkinElmer was used, and the measurement was performed in a helium atmosphere with a heating temperature of 250 ° C. and a heating time of 10 minutes. Other measurement conditions are as follows.
Split: inlet 25 mL / min, outlet 25 mL / min, injection volume 2.5%
GC column: EQUITY-1 (non-polar), 0.32 mm x 60 m x 0.25 μm
He flow rate: 1.5 ml / min
MS measurement range: 35 to 400 amu (scan500ms)
Ionization voltage: 70eV
MS temperature: Ion source 230 ° C and interface 250 ° C.

(Die share strength of laminated body before heating)
The die shear strength of the laminate before heating was evaluated based on the "solder joint shear test method" described in JIS Z 3198-7: Lead-free solder test method-Part 7 Solder joint shear test method for chip parts.

FIG. 3 schematically shows a measuring device for measuring the die shear strength of the laminated body. The laminate 1 obtained in each Example and Comparative Example was set in the shear strength tester 105 without heat treatment, and a load was applied to the chip 101 in a direction parallel to the adhesive surface of the substrate 100 at a shear rate of 6 mm / min. rice field. The relationship between displacement and load was graphed to obtain a stress-strain curve, and the joint strength was measured. In the stress-strain curve, the stress value at the breaking point was defined as the die shear strength (shear strength).

(Die share strength of laminated body after heating)
The laminate 1 obtained in Examples and Comparative Examples was heat-treated under the same conditions as the gas generation test, that is, under the heating conditions of 250 ° C. for 10 minutes in a helium atmosphere. The laminated body 1 obtained in the heat-treated Examples and Comparative Examples is stress-strained by graphing the relationship between displacement and load under the same measuring device and the same measuring conditions as the die shear strength of the laminated body before heating. A strain curve was obtained and the joint strength was measured. In the stress-strain curve, the stress value at the breaking point was defined as the die shear strength (shear strength).

Table 1 shows the composition of the connecting material for forming the laminate obtained in each Example and Comparative Example, and the amount of gas generated by the fine particles contained in the connecting material. In addition, Table 1 shows the values of the die shear strength before and after heating of the laminates obtained in each Example and Comparative Example.

From the results in Table 1, it was found that the silicone particles obtained in Production Examples 1 and 2 and the resin particles obtained in Production Example 4 generated more than 4000 ppm of corrosive compounds in the gas generation test. Then, it was found that the die shear strength of the laminate containing these fine particles was significantly reduced by the heat treatment. Both the silicone particles obtained in Production Examples 1 and 2 and the resin particles obtained in Production Example 4 are mainly composed of 1,1,3,3-tetramethyldisiloxane or a compound derived from them by a gas generation test. It was clarified from the results of GC-MS that corrosive compounds were generated. The detected 1,1,3,3-tetramethyldisiloxane may also contain a trace amount of fine particle decomposition products and polymers.

On the other hand, the silicone particles 3 obtained in Production Example 3 and the resin particles 2 obtained in Production Example 5 have a corrosive compound of less than 4000 ppm in the gas generation test, and the laminate containing these fine particles can be heat-treated. The die shear strength was almost unchanged from that before heating. In the silicone particles 3 obtained in Production Example 3, a gas generation test revealed that 1,1,3,3-tetramethyldisiloxane or a corrosive compound containing a compound derived from the same was generated as a main component. It became clear from the result of GC-MS. The detected 1,1,3,3-tetramethyldisiloxane may also contain a trace amount of fine particle decomposition products and polymers.

The above results show that the Cu substrate can be easily peeled off by the heat treatment of the laminated body containing fine particles having a gas component (corrosive compound) of 4000 ppm or more generated in the gas generation test in the joining member. There is.

Considering that the laminated body has the same basic structure as the electrode structure, from the results of Examples and Comparative Examples, the connecting structure provided with the joining member containing the fine particles of the present invention can be easily heat-treated. It can be said that it was shown that the member to be connected can be separated from the connecting member. Therefore, the connection structure provided with the joining member containing the fine particles of the present invention is excellent in reworkability, and the operator can safely perform the rework work.

10: Fine particles 11: First connection target member 12: Second connection target member 20: Connection member

Claims (8)

In a helium atmosphere, the gas component generated under heating conditions at 250 ° C. for 10 minutes is 4000 ppm or more.
Fine particles, wherein the gas component is a corrosive compound having a property of corroding at least one selected from the group consisting of copper, gallium silicate, silicon and silicon carbide . The fine particles according to claim 1, wherein the corrosive compound does not have the property of corroding silver. The fine particles according to claim 1 or 2 , wherein the corrosive compound has a property of vaporizing one or more selected from the group consisting of copper, gallium silicate, silicon and silicon carbide. The fine particles according to any one of claims 1 to 3 , wherein the surface is coated with a metal. A connecting material containing the fine particles according to any one of claims 1 to 4 and metal particles. A connection structure in which a first connection target member and a second connection target member are connected by a connection member containing a cured product of the connection material according to claim 5 . The connection structure according to claim 6 , wherein the shear strength between the first connection target member or the second connection target member and the connection member is reduced by 60% or more after heat treatment at 250 ° C. for 10 minutes. A method for reworking a connection structure, comprising a step of heating the connection structure according to claim 6 or 7 to peel off the first connection target member and / or the second connection target member from the connection member.

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