WO2020040184A1

WO2020040184A1 - Joining composition

Info

Publication number: WO2020040184A1
Application number: PCT/JP2019/032597
Authority: WO
Inventors: 智文渡辺; 啓資田中
Original assignee: バンドー化学株式会社
Priority date: 2018-08-23
Filing date: 2019-08-21
Publication date: 2020-02-27
Also published as: JP6736782B2; JPWO2020040184A1

Abstract

The present invention provides a joining composition whereby joining can be performed without pressure even at relatively low temperature, and excellent joining strength and excellent heat-resistant reliability are obtained. The present invention is a joining composition containing silver fine particles coated with a primary amine, and a dispersion medium, the primary amine having a carbon number of 4 to 12 and a boiling point of 300°C or lower, the silver fine particles including first silver fine particles having an average particle diameter of 45 to 75 nm and second silver fine particles having an average particle diameter of 200 to 550 nm, and the dispersion medium including an unsaturated hydrocarbon.

Description

Bonding composition

The present invention relates to a bonding composition.

Conventionally, a joining material has been used to mechanically, electrically, and / or thermally join a metal component and a metal component. Examples of the bonding material include a solder, a conductive adhesive, a silver paste, and an anisotropic conductive film. These joining materials may be used not only for joining metal parts, but also for joining metal parts to ceramic parts, resin parts, and the like. For example, in recent years, a bonding material may be used for bonding a light emitting element such as a light emitting diode (LED), a semiconductor chip, and the like to a substrate, and further bonding these substrates to a heat dissipation member.

High-brightness lighting devices and light-emitting devices with light-emitting elements such as LEDs, and semiconductor devices with semiconductor elements that operate at high temperatures and with high efficiency called power devices, etc., tend to have high driving temperatures when using the devices. is there. Since the melting point of solder is lower than the driving temperature of these devices, it is not suitable for bonding light emitting elements such as LEDs, semiconductor chips, and the like. Furthermore, in recent years, lead-free bonding materials have been demanded from the viewpoint of environmental protection and the regulations of the "European Parliament and Council Directive on the Restriction of the Use of Specific Hazardous Substances in Electric and Electronic Equipment" (RoHS).

As a new bonding material having high heat resistance and not containing lead, bonding materials containing metal nanoparticles have been studied (for example, see Patent Documents 1 to 9).

Patent Document 1 discloses that in a metal paste obtained by kneading a solid content composed of silver particles and a solvent, the solid content is composed of silver particles containing 30% or more of silver particles having a particle diameter of 100 to 200 nm on a particle number basis. The silver particles constituting the solid content have an average particle size of 60 to 800 nm, and the silver particles constituting the solid content are amine compounds having a total of 4 to 8 carbon atoms as a protective agent. Disclosed are metal pastes that are bonded and exhibit an exothermic peak below 200 ° C. due to sintering of silver particles in TG-DTA analysis.

Patent Document 2 discloses a bonding material containing silver powder in which the particle size distribution of primary particles has a first peak in a particle size range of 20 to 700 nm and a second peak in a particle size range of 200 to 500 nm. It is possible to form a bonding layer having high shear strength even with a heat treatment at a temperature lower than the conventional heating temperature. A method for manufacturing a bonded article is disclosed.

Patent Document 3 includes copper particles and a plurality of silver fine particles covering the copper particles, and at least a part of the surface of the silver fine particles is coated with an amine compound having a boiling point of 70 to 300 ° C. under atmospheric pressure. And composite particles in which the silver fine particles have a particle size of 1 to 500 nm. And since such composite particles are sintered by heating at less than 300 ° C., the composite particles form a silver metal bond on the surface thereof, and the metal bond or the metal bond is formed at the interface between the composite particle and the adherend. It is disclosed that diffusion occurs and the bonding strength is high, and as a result, a sintered body having excellent adhesion to a semiconductor member (semiconductor element, semiconductor element mounting support member) and high adhesion reliability can be obtained. ing.

Japanese Patent No. 5795096 JP-A-2017-106086 JP 2016-129101 A JP-A-2005-232181 International Publication No. WO 2013/108408 JP 2014-74132 A JP 2011-94223 A JP 2008-161907 A JP 2011-175871 A

Conventionally, in the case of joining using metal nanoparticles, the joining may be performed while applying pressure in an inert atmosphere at 300 to 350 ° C. Further, in joining a light emitting element such as an LED, a semiconductor chip, or the like, from the viewpoint of preventing damage to these devices at the time of joining, it is desirable that sintering can be performed at a firing temperature of less than 300 ° C.

In recent years, devices including light emitting elements such as LEDs, semiconductor chips, and the like have been demanded to increase the output, and may be highly integrated or the input power may be increased. Therefore, the driving temperature of these devices is higher, and the usage environment of the bonding material tends to be harsher. For bonding of light emitting elements such as LEDs and semiconductor chips, high bonding strength and heat resistance reliability are required. Desired.

Patent Documents 1 to 9 disclose metal pastes containing metal particles, and disclose that a bonding strength can be obtained at a relatively low temperature without applying pressure. However, there is room for further study in order to achieve higher bonding strength.

The present invention has been made in view of the above problems, and can be bonded without applying pressure even at a relatively low temperature, has excellent bonding strength, and a bonding composition that has excellent heat resistance. provide.

The present inventors have conducted intensive studies to achieve the above object, and as a result, through a step of firing at a relatively low temperature without applying pressure, excellent bonding strength, and a bonding material having excellent heat resistance reliability. In order to achieve the above object, it is necessary to use two types of fine silver particles coated with a specific primary amine and having different average particle diameters, and to further contain an unsaturated hydrocarbon as a dispersion medium. They have found that they are effective and have reached the present invention.
The present inventors have found that the above problem can be solved by the following constitution.

That is, the present invention relates to a bonding composition containing silver fine particles coated with a primary amine and a dispersion medium, wherein the primary amine has 4 to 12 carbon atoms and a boiling point of Is 300 ° C. or less, and the silver fine particles include first silver fine particles having an average particle size of 45 to 75 nm and second silver fine particles having an average particle size of 200 to 550 nm. And unsaturated hydrocarbons.

The second silver fine particles are preferably formed from a silver complex compound different from the first silver fine particles.

The weight ratio of the first silver fine particles to the second silver fine particles is preferably 4: 6 to 7: 3.

The dispersion medium preferably contains at least an organic solvent having a hydroxyl group.

Preferably, the unsaturated hydrocarbon is ricinoleic acid.

The bonding composition preferably does not contain a polymer dispersant.

It is preferable that the porosity of the bonding layer obtained by heating and baking the bonding composition at 275 ° C. is 10% or less.

According to the present invention, it is possible to provide a bonding composition that can be bonded without applying pressure even at a relatively low temperature, has a low porosity, has excellent bonding strength, and has excellent heat resistance reliability. it can.

The bonding composition of the present invention is a bonding composition containing silver fine particles coated with a primary amine and a dispersion medium, wherein the primary amine has 4 to 12 carbon atoms. The silver fine particles having a boiling point of 300 ° C. or less, the first silver fine particles having an average particle size of 45 to 75 nm, and the second silver fine particles having an average particle size of 200 to 550 nm, The dispersion medium contains an unsaturated hydrocarbon.

In addition, the boiling point shown in this specification is a value at 1 atmosphere (at atmospheric pressure).

The primary amine is a component that binds to at least a part of the surface of the silver fine particles to form a colloid. The primary amine does not need to cover the entire surface of the silver fine particles, but only needs to cover at least a part of the surface of the silver fine particles to the extent that a colloid can be formed. By being coated with the primary amine, the dispersion stability of the silver fine particles in the bonding composition of the present invention can be improved, and aggregation can be prevented. On the other hand, when the bonding composition of the present invention is fired, if the primary amine remains, the fusion of silver fine particles is inhibited. It is preferable that the secondary amine is an amine which is easily released from the surface of the silver fine particles even at a relatively low temperature.

Therefore, from the above viewpoint, the primary amine coating the silver fine particles of the present invention has 4 to 12 carbon atoms and a boiling point of 300 ° C. or less. It is not particularly limited as long as it is such a primary amine, and it may be linear or branched, and may have a side chain.
Specifically, for example, diamines such as 1,4-butanediamine and 1,5-pentanediamine; amino alcohols such as pentanolamine and aminoisobutanol; butylamine, pentylamine, hexylamine, heptylamine, octylamine; Alkylamines such as nonylamine, decylamine, undecylamine and dodecylamine (linear alkylamines, which may have side chains); cycloalkylamines such as cyclopentylamine and cyclohexylamine; 3-methoxypropylamine and the like Alkoxyamine; diglycolamine; aniline; allylamine and the like. In addition, the carbon number of the primary amine is the total of the carbon numbers of the main chain and the side chain.

The primary amine may be, for example, a compound containing a functional group other than an amine, such as a hydroxyl group, a carboxyl group, an alkoxy group, a carbonyl group, an ester group, and a mercapto group. The primary amines may be used alone or in combination of two or more.

The primary amine has a boiling point of 300 ° C. or less, preferably 250 ° C. or less, from the viewpoint of easily detaching from the surface of silver fine particles even at a relatively low temperature.
By using the amine which is released from the surface of the silver fine particles at a lower temperature, fusion of the silver fine particles can be further promoted when the bonding composition of the present invention is fired.

The bonding composition of the present invention contains, as silver fine particles, first silver fine particles having an average particle size of 45 to 75 nm and second silver fine particles having an average particle size of 200 to 550 nm. That is, when the distribution of silver fine particles is measured, the bonding composition of the present invention has a first peak in a particle size range of 45 to 75 nm and a second peak in a particle size range of 200 to 550 nm. Having a peak of Since the first silver fine particles have an average particle size of 45 to 75 nm, the specific surface area is large and the amount of the primary amine to be coated per unit weight is large. For this reason, volume shrinkage at the time of firing becomes large, and cracks and voids tend to be easily generated after joining. On the other hand, since the second silver fine particles have an average particle diameter of 200 to 550 nm, the specific surface area is small, and the amount of the primary amine to be coated per unit weight is small. Therefore, the volume shrinkage during firing is small, and cracks and voids tend to hardly occur after joining. By using such first silver fine particles and second silver fine particles in combination, volume shrinkage during firing can be suppressed, cracks and voids can be hardly generated, and a sintered body having a higher density can be obtained. Obtainable.

Here, it is generally known that, when noble metals having a high melting point are formed into fine particles, the melting point is greatly reduced by a quantum size effect, that is, a quantum mechanical effect developed by the formation of nanoparticles. Therefore, it is considered that it is important to reduce the average particle size of the silver fine particles contained in the bonding composition in order to realize the firing at the lowest possible temperature for the bonding composition of the present invention.

The second silver fine particles have a larger average particle size than the first silver fine particles, and the influence of the size effect as described above is reduced, and the firing temperature becomes high. The firing temperature can be suppressed to a relatively low temperature by using the first silver fine particles and the second silver fine particles in combination.

That is, the bonding composition of the present invention includes the first silver fine particles and the second silver fine particles as silver fine particles, thereby realizing firing at a relatively low temperature and firing after bonding. The generation of cracks and voids in the consolidated body is suppressed, and a sintered body having a low porosity, a higher density, and excellent bonding strength can be obtained.

The average particle size of the first silver fine particles is 45 to 75 nm. The bonding composition of the present invention can sinter metal particles even at a firing temperature exceeding 300 ° C., but contains the first silver fine particles having an average particle size of 45 to 75 nm, so that the melting point drop is reduced. Then, the metal particles can be sintered at a relatively low temperature (for example, 300 ° C. or less, preferably about 275 ° C.). Further, the dispersibility of the metal particles in the bonding composition can be hardly changed with time. When the average particle diameter of the first silver fine particles is less than 45 nm, the specific surface area of the silver fine particles increases, so that the viscosity of the bonding composition increases and the handleability decreases. In addition, when the surface of the silver fine particles is coated with a primary amine, the amount of the primary amine increases, the organic matter remains after firing, and the density of the sintered body decreases. descend. On the other hand, when the average particle diameter of the first silver fine particles exceeds 75 nm, a decrease in the melting point hardly occurs, and the silver fine particles hardly sinter at a relatively low temperature. A preferred lower limit of the average particle size of the first silver fine particles is 47 nm, and a preferred upper limit is 72 nm.

The average particle size of the second silver fine particles is 200 to 550 nm. If the average particle size of the second silver fine particles is less than 200 nm, the specific surface area of the silver fine particles increases, so that the amount of the primary amine to be coated increases, and the shrinkage during firing increases. In some cases, the overall volume shrinkage cannot be sufficiently suppressed. That is, cracks and voids may easily occur in the sintered body after joining. In addition, the amount of the primary amine covering the surface of the second silver fine particles increases, and an organic substance remains after firing, resulting in a decrease in the density of the sintered body, which may cause a decrease in bonding strength. On the other hand, when the average particle diameter of the second silver fine particles exceeds 550 nm, when the bonding composition of the present invention is sandwiched between the members to be bonded, a gap is generated due to the metal particles having a large particle diameter, and the bonding strength is reduced. May decrease. A preferred lower limit of the average particle size of the second metal particles is 240 nm, and a preferred upper limit is 450 nm.

In the present specification, the “average particle size” is a primary average particle size of silver fine particles, and refers to a number average particle size. The number average particle size can be determined, for example, by converting an image obtained using a scanning electron microscope (SEM) (for example, Model S-4800 manufactured by Hitachi High-Technologies Corporation) into image processing software (for example, WinROOF, manufactured by MITANNI CORPORATION). ) Can be calculated.

In the present invention, the second silver fine particles are preferably formed from a silver complex compound different from the first silver fine particles. By being formed from different silver complex compounds, it is possible to obtain silver fine particles having different amounts of primary amine covering the surfaces of the first and second silver fine particles and different in volume shrinkage when both are fired. In other words, the first and second silver fine particles can have different average particle diameters by being formed from different silver complex compounds.

The amount of the primary amine covering the first silver fine particles in the solid content of the silver fine particles is preferably 0.5% by weight or more and 3.0% by weight or less. Preferably, the amount of the primary amine is more than 0% by weight and less than 0.5% by weight.

The silver fine particles in the present invention preferably contain the first silver fine particles and the second silver fine particles in a weight ratio of 4: 6 to 7: 3. Thereby, the joining strength can be further improved while realizing the low-temperature sinterability. When the weight of the first silver fine particles is less than 40 parts by weight based on 60 parts by weight of the second silver fine particles, the first silver fine particles having an average particle size of 45 to 75 nm in the bonding composition. And the silver fine particles may be difficult to sinter at a relatively low temperature. On the other hand, when the weight of the first silver fine particles exceeds 70 parts by weight with respect to 30 parts by weight of the second silver fine particles, volume shrinkage during firing becomes large, and cracks and voids are easily generated in the sintered body. Therefore, the bonding strength tends to decrease. When the weight of the second silver fine particles is larger than the weight of the first silver fine particles, the flowability of the bonding composition is reduced and the handleability is reduced, while the weight reduction rate tends to decrease. The weight ratio between the first silver fine particles and the second silver fine particles can be determined in consideration of the balance between handleability and weight reduction rate.

The total content of the primary amine in the bonding composition is preferably 0.1 to 15% by weight. When the total content of the primary amine component is 0.1% by weight or more, the conductivity of the obtained bonding composition tends to be improved. Dispersion stability tends to be good. A more preferred lower limit of the total content of the primary amine is 0.2% by weight, a more preferred upper limit is 5% by weight, a still more preferred lower limit is 0.3% by weight, and a still more preferred upper limit is 4% by weight. %. The total content of the primary amine can be measured by thermogravimetric analysis.

The bonding composition of the present invention contains a dispersion medium. By containing the dispersion medium, the viscosity of the bonding composition can be adjusted, and the handleability can be improved.
The bonding composition of the present invention preferably does not contain, as a dispersion medium, a primary amine covering the first silver fine particles and a primary amine covering the second silver fine particles. When the dispersion medium contains the same organic components as the first and second silver fine particles, the dispersibility of the silver fine particles tends to be improved because compatibility is obtained, but the volatility is high in an uncoated state. This is because the bonding composition may not have stability.

The dispersion medium contains an unsaturated hydrocarbon. Thereby, the silver fine particles, which are solids in the bonding composition of the present invention, are dispersed in the dispersion medium, and even when the content of the dispersion medium with respect to the entire bonding composition is small, it is possible to form a paste. It becomes possible. This facilitates handling of the bonding composition of the present invention.

Examples of the unsaturated hydrocarbon include acetylene, benzene, 1-hexene, 1-octene, 4-vinylcyclohexene, terpene alcohol, allyl alcohol, oleyl alcohol, 2-palmitoleic acid, petroselinic acid, oleic acid, and elaidic acid. Thiocyanic acid, ricinoleic acid, linoleic acid, linoleic acid, linolenic acid, arachidonic acid, acrylic acid, methacrylic acid, gallic acid and salicylic acid.

Among them, unsaturated hydrocarbons having a hydroxyl group are preferred. The hydroxyl group is easily coordinated on the surface of the silver fine particles, and the aggregation of the silver fine particles can be suppressed. Examples of the unsaturated hydrocarbon having a hydroxyl group include terpene alcohol, allyl alcohol, oleyl alcohol, thiocyanic acid, ricinoleic acid, gallic acid and salicylic acid. Preferred are unsaturated fatty acids having a hydroxyl group, such as thiocyanic acid, ricinoleic acid, gallic acid, and salicylic acid.

Preferably, the unsaturated hydrocarbon is ricinoleic acid. Ricinoleic acid has a carboxyl group and a hydroxyl group, adsorbs on the surface of silver fine particles to uniformly disperse the silver fine particles, and promotes fusion of the silver fine particles and bonding to the object.

The content of the unsaturated hydrocarbon relative to the entire dispersion medium in the bonding composition of the present invention is preferably 0.1% by weight or more and 2.0% by weight or less. When the content of the unsaturated hydrocarbon in the dispersion medium is less than 0.1% by weight, the dispersibility of the silver fine particles in the dispersion medium may be deteriorated. There is a possibility of causing a problem that hinders sintering of the silver fine particles.
The content of the unsaturated hydrocarbon is more preferably from 0.2% by weight to 1.5% by weight.

As the dispersion medium, various ones can be used as long as the effects of the present invention are not impaired. For example, water or an organic solvent can be used. Examples of the organic solvent include hydrocarbons (excluding the unsaturated hydrocarbons), alcohols and ethers.

Examples of the hydrocarbon include an aliphatic hydrocarbon, a cyclic hydrocarbon, and an alicyclic hydrocarbon, and may be used alone or in combination of two or more.

Examples of the aliphatic hydrocarbon include, for example, saturated or unsaturated aliphatic hydrocarbons such as tetradecane, octadecane, heptamethylnonane, tetramethylpentadecane, hexane, heptane, octane, nonane, decane, tridecane, methylpentane, normal paraffin, and isoparaffin. Hydrogen.

Examples of the cyclic hydrocarbon include toluene, xylene and the like.

Examples of the alicyclic hydrocarbon include limonene, dipentene, terpinene, terpinene (also referred to as terpinene), nesol, sinene, orange flavor, terpinolene, terpinolene (also referred to as terpinolene), ferrandrene, mentadien, terben, and dihydro. Cymen, moslen, isoterpinene, isoterpinene (also referred to as isoterpinene), klitmen, kautushin, kagepten, oilymen, pinene, turpentine, menthan, pinane, terpene, cyclohexane, and the like.

The alcohol is a compound containing one or more OH groups in the molecular structure, and includes an aliphatic alcohol, a cyclic alcohol and an alicyclic alcohol, each of which may be used alone or in combination of two or more. Good. Further, a part of the OH group may be derived to an acetoxy group or the like as long as the effect of the present invention is not impaired.

Examples of the aliphatic alcohol include heptanol, octanol (eg, 1-octanol, 2-octanol, 3-octanol), decanol (eg, 1-decanol), tridecanol (eg, isotridecanol), lauryl alcohol, and tetradecyl alcohol. And saturated or unsaturated aliphatic alcohols having 6 to 30 carbon atoms, such as cetyl alcohol, 2-ethyl-1-hexanol, octadecyl alcohol, hexadecenol and oleyl alcohol.

Examples of the cyclic alcohol include cresol and eugenol. Examples of alicyclic alcohols include, for example, cycloalkanols such as cyclohexanol; terpineols (including α, β, γ isomers or any mixture thereof) and terpene alcohols such as dihydroterpineol (monoterpene alcohols and the like). Dihydroterpineol; myrtenol; sobrelol; menthol; carveol; perillyl alcohol; pinocalveol; sobrelol;

Examples of the ether include hexyl ether, butyl carbitol, hexyl carbitol, dipropylene glycol-n-butyl ether, tersolve THA-90, tripropylene glycol methyl ether, triethylene glycol monomethyl ether, diethylene glycol dibutyl ether, and diethylene glycol monohexyl. Examples include ether, triethylene glycol butyl methyl ether, dipropylene glycol monobutyl ether, tetraethylene glycol dimethyl ether, tersolve TOE-100, butyl carbitol acetate, and triethylene glycol methyl ether acetate.

The dispersion medium preferably contains at least an organic solvent having a hydroxyl group (OH group). Examples of the organic solvent having a hydroxyl group include those having a hydroxyl group among the above-mentioned alcohols and hydrocarbons, and those having a hydroxyl group among the above-mentioned ethers. By containing at least an organic solvent having a hydroxyl group as a dispersion medium, compatibility with silver fine particles and volatility can be achieved.
From the viewpoint of achieving both compatibility with the silver fine particles and volatility, it is preferable to use an ether having a hydroxyl group as the organic solvent, such as hexyl carbitol.

The content of the organic solvent having a hydroxyl group with respect to the entire dispersion medium is preferably 50% by weight or more and 99% by weight or less. If the content of the organic solvent in the dispersion medium is less than 50% by weight, the dispersibility of the silver fine particles in the dispersion medium may be deteriorated. If the content exceeds 99% by weight, the joining property may be deteriorated. May occur.
The content of the organic solvent having a hydroxyl group is more preferably 60% by weight or more and 98% by weight or less.

It is preferable that the content of the above-mentioned dispersion medium with respect to the whole bonding composition of the present invention is 6% by weight or more and 15% by weight or less. When the content of the dispersion medium is less than 6% by weight, the shearing viscosity of the bonding composition is too high, so that the handleability is poor and it is difficult to apply to the member to be bonded. On the other hand, when the content of the dispersion medium exceeds 15% by weight, the rate of weight loss by thermal analysis from 25 ° C. to 550 ° C. increases. Further, since the content of silver fine particles in the bonding composition is reduced, the density of the sintered body is reduced, and sufficient bonding strength may not be obtained.

The dispersion medium preferably has a boiling point of 250 ° C. or higher. This is because the bonding composition containing such a dispersion medium does not dry at room temperature during printing or after application, and is excellent in handleability. Further, the dispersion medium is preferably liquid at ordinary temperature.

From the viewpoint described above, the dispersion medium is preferably a mixture of at least one of the hydrocarbon, the alcohol, and the ethanol. In particular, hexyl carbitol (boiling point: 258 ° C.) and butyl carbitol acetate (boiling point: 245 ° C.) and the boiling point is preferably 250 ° C. or higher.

Further, it is preferable that the bonding composition of the present invention does not contain a polymer dispersant. This is because the polymer dispersant tends to remain in the bonding layer even after firing at a temperature of 300 ° C. or less, hinder sintering, and may adversely affect the bonding reliability.

The porosity of the bonding layer obtained by heating and baking the bonding composition of the present invention at 275 ° C. is preferably 10% or less. Further, it is preferable that the porosity of the bonding layer obtained by heating and firing at 275 ° C. without pressure is 10% or less. This is because, in such a state, from the viewpoint of heat resistance reliability, the crack progresses slowly with respect to strain due to a difference in linear expansion coefficient.

The object to which the bonding composition of the present invention is used includes Au, Ag, Cu and the like, and pure Cu can be suitably used. In the case where pure Cu is used as an object to be joined, there arises a problem that a surface oxide film must be removed in order to join. Therefore, the bonding composition of the present invention preferably contains an unsaturated hydrocarbon containing a carboxylic acid such as ricinoleic acid as a dispersion medium. Carboxylic acid has an effect of removing an oxide film on the copper surface, and is effective when bonding to the copper surface without pressure.
Further, the bonding composition of the present invention is heated and fired in an air atmosphere or an inert atmosphere, but when solid Cu is used as an object to be bonded, it is heated and fired in an inert atmosphere. Preferably, there is.
When the atmosphere in which the bonding layer (also referred to as a sintered body) is formed is an oxidizing atmosphere including oxygen, which is an air atmosphere, an oxide film at an interface with the body to be bonded, which may adversely affect bonding strength. Concern about formation. When using Au or Ag, almost no oxide film is formed, but when using pure Cu, it is considered that such an effect tends to be remarkable. Therefore, it is preferable that the substrate be heated and fired under an inert atmosphere such as nitrogen which can eliminate such an influence. The bonding composition of the present invention exhibits sufficient bonding strength even when heated and baked in an inert atmosphere.

The bonding composition of the present invention, in addition to the components described above, within a range that does not impair the effects of the present invention, to impart a function such as appropriate viscosity, adhesion, drying property, or printability according to the purpose of use. In addition, for example, optional components such as an oligomer component, a resin component, an organic solvent (which may dissolve or disperse a part of solid content), a thickener, a surfactant, and a surface tension modifier, which serve as a binder, Components may be added. Such optional components are not particularly limited.

Examples of the resin component include a polyester resin, a polyurethane resin (for example, one using blocked isocyanate), a polyacrylate resin, a polyacrylamide resin, a polyether resin, a melamine resin, a terpene resin, and the like. These may be used alone or in combination of two or more.

Examples of the organic solvent, except those mentioned as the dispersion medium, include, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, 2-propyl alcohol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,2,6-hexanetriol, 1-ethoxy-2-propanol, 2-butoxyethanol, ethylene glycol, diethylene glycol, triethylene glycol, having a weight average molecular weight of 200 to 1,000 Polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol having a weight average molecular weight in the range of 300 to 1,000, N, N-dimethylformamide, dimethyl sulfoxide, - methyl-2-pyrrolidone, N, N- dimethylacetamide, glycerin, or acetone and the like may be used each of which alone or in combination of two or more.

Examples of the thickener include clay minerals such as clay, bentonite and hectorite; for example, emulsions such as polyester emulsion resin, acrylic emulsion resin, polyurethane emulsion resin and blocked isocyanate; methyl cellulose, carboxymethyl cellulose, hydroxy Cellulose derivatives such as ethylcellulose, hydroxypropylcellulose and hydroxypropylmethylcellulose; polysaccharides such as xanthan gum and guar gum; and the like, each of which may be used alone or in combination of two or more.

The surfactant is not particularly limited, and any one of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. Examples thereof include an alkylbenzene sulfonate, a quaternary ammonium salt, and the like. Is mentioned. Since the effect can be obtained with a small addition amount, a fluorine-based surfactant is preferable.

In the bonding composition of the present invention, the first and second silver fine particles are present as silver colloid particles. In general, regarding the form of the silver colloid particles, for example, a silver colloid particle formed by attaching an organic substance to a part of the surface of the silver fine particle, the silver fine particle as a core, and the surface is coated with an organic substance. Examples of the silver colloid particles include, but are not particularly limited to, silver colloid particles formed by mixing them. In the present invention, silver colloid particles having a primary amine as an organic substance attached thereto, silver colloid particles coated with a primary amine, and silver colloid particles composed of a mixture thereof are referred to as silver fine particles. That. The silver fine particles in the present specification are preferably silver colloid particles composed of silver fine particles as a core and the surface thereof coated with a primary amine.

In the present specification, the silver fine particles coated with the primary amine are a primary amine to an organic substance adhering to a part of the surface of the silver fine particles and / or an organic substance coating the surface of the silver fine particles. Is 50% by weight or more, it is referred to as silver fine particles coated with a primary amine. Here, the amount of the primary amine in the organic substance covering the silver fine particles can be measured, for example, by a method such as thermogravimetric analysis.

The shear viscosity of the bonding composition of the present invention may be appropriately adjusted within a range that does not impair the effects of the present invention. The shear viscosity at 25 ° C. is 15 to 200 Pa · s at a shear rate of 10 s ⁻¹ . Is preferred. By setting the content within the above range, for example, it can be suitably used for a purpose of bonding a light emitting element such as an LED, a semiconductor chip and the like to a substrate, and a purpose of further bonding these substrates to a heat dissipation member. A more preferred lower limit of the shear viscosity is 25 Pa · s, and a more preferred upper limit is 180 Pa · s.

The adjustment of the shear viscosity is performed by adjusting the particle size of the silver fine particles, adjusting the content of the primary amine which is an organic substance, adjusting the addition amount of the dispersion medium and other components, adjusting the mixing ratio of each component, and using a thickener. And the like. The above-mentioned shear viscosity can be measured by a cone plate type viscometer (for example, a rheometer MCR301 manufactured by Anton Paar).

The joining strength when the members to be joined are joined with the joining composition of the present invention is preferably 20 to 150 MPa. When the bonding strength is 20 to 150 MPa, it can be suitably used for bonding a light emitting element such as an LED, a semiconductor chip or the like to a substrate, and bonding the substrate to a heat dissipation member. A more preferred lower limit of the bonding strength is 30 MPa, and a still more preferred lower limit is 50 MPa. The bonding strength is determined by applying a bonding composition to one of the members to be bonded, attaching the other member to be bonded, and sintering the resultant. For example, a bond tester (manufactured by Resca Corporation) Can be evaluated by performing a bonding strength test.

The bonding composition of the present invention has excellent heat resistance (also referred to as heat cycle reliability). Since the heat cycle reliability is good, it can be suitably used for bonding of a light emitting element such as an LED, a semiconductor chip, and the like in the manufacture of a device having a high driving temperature. The above-mentioned heat cycle reliability is, for example, 500 ° C. for a cycle in which a laminate obtained by sintering a joining composition and a member to be joined is held at −40 ° C. and 150 ° C. in an air atmosphere for 10 minutes each. It can be evaluated by performing a heat cycle test of up to 1000 cycles. The heat cycle test can be performed using, for example, a thermal shock tester (manufactured by Hutec). The rate of decrease in the bonding strength of the laminate after the heat cycle test with respect to the initial strength of the laminate is preferably less than 20%, more preferably less than 5%.

<Preparation of bonding composition>
The method for producing the bonding composition of the present invention is not particularly limited.First, a silver fine particle dispersion is prepared, and the silver fine particle dispersion and the dispersion medium are mixed with the various components as necessary. Thus, the bonding composition of the present invention can be obtained.

As a method for preparing the silver fine particle dispersion, a first step of preparing a mixed solution of a silver compound capable of decomposing by reduction to generate silver atoms and an organic protective component, and the silver compound in the mixed solution A second step of generating silver fine particles having an organic protective component adhered to at least a part of the surface by reduction. Hereinafter, a specific manufacturing method will be described.

In the first step, it is preferable to add a primary amine (hereinafter, simply referred to as an amine) in an amount of 1 mol or more per 1 mol of silver. When the amount of the amine is 1 mol or more per 1 mol of silver, the amine can be adhered to the surface of silver fine particles generated by reduction in a certain amount or more, and the silver fine particles are excellent in various dispersion media. High dispersibility and low-temperature sinterability.

Hereinafter, the method for producing silver fine particles will be specifically described, but since the following description is common to both the first silver fine particles and the second silver fine particles, it is simply referred to as “silver fine particles”.

Various known silver compounds can be used as a starting material for obtaining silver fine particles coated with an amine as an organic component. For example, a silver salt or a hydrate of a silver salt can be used. Specific examples include silver salts such as silver nitrate, silver sulfate, silver chloride, silver oxide, silver acetate, silver oxalate, silver formate, silver nitrite, silver chlorate, and silver sulfide. These are not particularly limited as long as they can be reduced, and may be dissolved in an appropriate solvent or used while being dispersed in the solvent. These may be used alone or in combination of two or more. Among them, silver oxalate is preferred. Silver oxalate is the simplest silver dicarboxylate, and the silver oxalate amine complex synthesized using silver oxalate is suitable for the synthesis of the silver fine particles of the present invention because the reduction proceeds in a short time at a low temperature. It is. Furthermore, when silver oxalate is used, by-products are not generated at the time of synthesis, and only carbon dioxide derived from oxalate ions is emitted out of the system, so that there is little labor for purification after the synthesis.

As a method of reducing the silver compound, a method of heating is preferable. The heating method is not particularly limited. As a method of reducing the silver compound by the heating, for example, heating a complex compound formed from a silver compound such as silver oxalate and an organic component such as an amine to reduce oxalate ions and the like contained in the complex compound There is a method of aggregating atomic silver generated by decomposition. By the above method, silver fine particles coated with an organic protective component such as an amine can be produced.

As described above, in the metal amine complex decomposition method for producing silver fine particles coated with an amine by thermally decomposing the complex compound of the silver compound in the presence of the amine, the decomposition of the silver amine complex which is a single kind of molecule is performed. Since atomic silver is generated by the reaction, it is possible to uniformly generate atomic silver in the reaction system. Therefore, compared with the case where silver atoms are generated by the reaction between a plurality of components, the nonuniformity of the reaction due to the fluctuation of the composition of the components constituting the reaction is suppressed, and particularly, a large amount of silver fine particles are produced on an industrial scale. It is advantageous when doing.

The composition of the liquid mixture in the first step and the reduction conditions (for example, heating temperature and heating time) in the second step are determined by selecting a desired silver fine particle as the first silver fine particle. The average particle size of the fine particles is adjusted to 45 to 75 nm, and if the desired silver fine particles are the second silver fine particles, the average particle size of the obtained silver fine particles is adjusted to 200 to 550 nm. The method for extracting silver fine particles from the silver fine particle dispersion obtained in the second step is not particularly limited, and examples thereof include a method for washing the silver fine particle dispersion.

Further, the primary amine which is an organic protective component is used not only in the first step of preparing a mixed liquid of the silver compound and the organic protective component (primary amine), but also in the mixed liquid obtained in the first step. It may be added in the second step of reducing the silver compound therein. The primary amine added in the first step and the primary amine added in the second step may be of the same type or different types. However, it is preferable that 50% by weight or more of the organic protective component attached to or coated on the obtained silver fine particles is a primary amine, and all of the organic protective components attached or coated on the obtained silver fine particles are primary amines. More preferably, it is a secondary amine.

In addition, in the metal amine complex decomposition method, an amine molecule is coordinated to a generated silver atom, and the movement of the silver atom during aggregation is controlled by the action of the amine molecule coordinated to the silver atom. It is assumed that As a result, according to the metal amine complex decomposition method, it is possible to produce very fine silver fine particles having a narrow particle size distribution.

Furthermore, a large number of amine molecules also have relatively weak coordination bonds on the surface of the manufactured silver fine particles, and these form a dense protective film on the surface of the silver fine particles, so that they have excellent storage stability. Thus, it becomes possible to produce organic-coated silver fine particles having a clean surface. Further, since the amine molecules forming the coating can be easily detached by heating or the like, it becomes possible to produce silver fine particles that can be sintered at a very low temperature.
In particular, in the bonding composition of the present invention, since the primary amine covering the silver fine particles has 4 to 12 carbon atoms and a boiling point of 300 ° C. or less, it can be used at a relatively low temperature of 300 ° C. or less. Are also easily separated from the silver fine particles.

Further, when a composite compound such as a complex compound is formed by mixing a solid silver compound and an amine, an amine is used by mixing with a dispersant having an acid value constituting a coating of the coated silver fine particles. This facilitates the production of a complex compound such as a complex compound, and makes it possible to produce the complex compound by short-time mixing. Further, by mixing and using the above amines, it is possible to produce coated silver fine particles having characteristics according to various uses.

The dispersion liquid containing silver fine particles coated with an organic protective component such as an amine obtained as described above contains, in addition to the silver fine particles, a counter ion of a metal salt, a dispersant, and the like. Tend to have a high electrolyte concentration and a high organic matter concentration. In the liquid in such a state, coagulation of silver fine particles occurs due to high conductivity and the like, and the liquid is easily precipitated. Alternatively, even if precipitation does not occur, the conductivity may be deteriorated if a counter ion of the metal salt or an excessive amount of a dispersant or the like remaining in an amount necessary for dispersion remain. Thus, by washing the solution containing the silver fine particles to remove excess residues, it is possible to reliably obtain the silver fine particles coated with the organic protective component.

As the washing method, for example, a dispersion liquid containing silver fine particles whose surface is coated with an organic protective component is allowed to stand for a certain period of time, and after removing the supernatant, a solvent (eg, water, methanol, (A mixed solvent of methanol / water, etc.), stirring the mixture, leaving the mixture to stand still for a certain period of time, and removing the supernatant liquid several times. Examples of other methods include a method of performing centrifugation instead of the above-mentioned standing, and a method of desalting with an ultrafiltration device or an ion exchange device. By removing excess residue and organic solvent by such washing, silver fine particles whose surface is coated with an organic protective component can be obtained.

Although the first silver fine particles and the second silver fine particles are obtained by the above method, the method of mixing the silver fine particle dispersion containing these and the dispersion medium is not particularly limited, and is conventionally known using a stirrer or a stirrer. The method can be performed by the following method. An ultrasonic homogenizer having an appropriate output may be applied by stirring with a spatula or the like.
Thus, the bonding composition can be prepared.

<Joining method>
When the bonding composition of the present invention is used, high bonding strength can be obtained in bonding members with heating even at a relatively low temperature (for example, 300 ° C. or lower, preferably about 275 ° C.). That is, a bonding composition application step of applying the bonding composition between a first member to be bonded and a second member to be bonded, and a step of coating the first member to be bonded and the second member to be bonded. A first bonding member and a second bonding member by a bonding step of firing and bonding the bonding composition applied in between at a desired temperature (for example, 300 ° C. or lower, preferably about 275 ° C.) And can be joined.

In the joining step, the first member to be joined and the second member to be joined can be pressed in a direction in which they face each other. However, it is also possible to obtain a sufficient joining strength without applying any pressure. One of the advantages. In the firing, the temperature can be raised or lowered stepwise. The surface of the member to be joined may be previously coated with a surfactant or a surface activator.

The term “coating” is a concept that includes a case where the bonding composition is applied in a plane and a case where the bonding composition is applied (drawn) in a linear manner. The shape of the coating film made of the bonding composition before being fired by heating can be a desired shape. Therefore, the shape of the sintered body (bonding layer) obtained by firing the bonding composition may be planar or linear. These planar bonding layer and linear bonding layer may be continuous or discontinuous, and may include a continuous portion and a discontinuous portion.

The first member to be joined and the second member to be joined are not particularly limited as long as they can be joined by applying a bonding composition and firing the mixture by heating. It is preferable that the member has heat resistance enough not to be damaged by temperature.

Examples of the material forming the first and second members to be joined include polyester such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyamide (PA), and polyimide ( PI), polyamide imide (PAI), polycarbonate (PC), polyether sulfone (PES), vinyl resin, fluororesin, liquid crystal polymer, ceramics, glass or metal.

The first and second members to be joined may have various shapes such as a plate shape or a strip shape, and may be rigid or flexible. The thicknesses of the first and second members to be joined can also be appropriately selected. A member having a surface layer formed thereon or a member having been subjected to a surface treatment such as a hydrophilization treatment may be used as the first and second members to be joined for the purpose of improving adhesion or adhesion, or for other purposes. .

Examples of the first and second members to be joined include a resin substrate, a metal plate, a light emitting element such as an LED, a semiconductor chip, a ceramic substrate on which an electronic circuit is formed, and the like. In addition to copper, it can be suitably used for metals such as gold and silver.

Various methods can be used for applying the bonding composition to the members to be bonded, and examples thereof include dipping, screen printing, spraying, bar coating, spin coating, ink jet, dispenser, and pin transfer. Method, stamping method, coating method using a brush, casting method, flexo method, gravure method, offset method, transfer method, hydrophilic / hydrophobic pattern method, syringe method, pin transfer, stencil printing and the like can be used. In particular, the bonding composition of the present invention has a high solid content concentration, and thus can be suitably used for dispensers, pin transfer, and stencil printing.

The method of performing the baking is not particularly limited, for example, using a conventionally known oven or the like, so that the temperature of the bonding composition applied or drawn on the member to be bonded is, for example, 300 ° C. or less. It can be joined by firing. The lower limit of the firing temperature is not necessarily limited, and is preferably a temperature at which members to be bonded can be bonded to each other, and a temperature within a range that does not impair the effects of the present invention. The lower limit of the firing temperature is, for example, 230 ° C.

The environment in which the above-described firing is performed may be either an air atmosphere or an inert atmosphere, but the firing can be suitably performed in an inert atmosphere. In particular, when joining members to be joined having pure copper on the surface, firing is preferably performed in a nitrogen atmosphere.

In addition, the bonding composition of the present invention utilizes a conventional thermosetting of an epoxy resin or the like, and is different from one that obtains bonding strength after firing. As described above, sufficient bonding strength is obtained by sintering the metal particles. It is obtained. Therefore, even if the remaining organic matter is degraded or decomposed or disappears after being put in a use environment higher than the joining temperature after joining, there is no possibility that the joining strength is reduced, and the heat resistance is excellent. ing.

According to the bonding composition of the present invention, for example, even when fired by heating at a low temperature of 300 ° C. or less, preferably about 275 ° C., excellent bonding strength can be obtained, and thus the members to be bonded relatively weak to heat are bonded. be able to. Further, the firing time is not particularly limited, and may be any firing time that can be joined according to the firing temperature.

In the present embodiment, the surface treatment of the member to be joined may be performed in order to further enhance the adhesion between the member to be joined and the joining layer. Examples of the surface treatment method include a method of performing a dry treatment such as a corona treatment, a plasma treatment, a UV treatment, and an electron beam treatment, and a method of previously providing a primer layer or a receiving layer of a bonding composition on a base material. Can be

As described above, the embodiments of the present invention have been described, but the present invention is not limited thereto. The bonding composition of the present invention further contains, for example, inorganic particles such as tin-doped indium oxide, alumina, barium titanate, and lithium iron phosphate having excellent conductivity, heat conductivity, dielectric properties, and ion conductivity. May be.

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

(Example 1)
<Preparation of silver fine particles A>
While sufficiently stirring 3.0 g of 3-methoxypropylamine (boiling point: 116 ° C.) with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put in a thermostat at 100 ° C. and reacted for about 15 minutes. Further, 20 g of dodecylamine (boiling point: 249 ° C.) was added thereto and reacted at the same temperature for 15 minutes.

In order to replace the dispersion medium of the suspension after the reaction, 10 ml of methanol was added to the suspension, followed by stirring. Then, silver fine particles A were precipitated and separated by centrifugation, and the supernatant was discarded. 10 ml of methanol was again added to the separated silver fine particles A, and the mixture was stirred and centrifuged to precipitate and separate the silver fine particles A.

<Preparation of silver fine particles B>
While sufficiently stirring 6.0 g of diglycolamine with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put in a thermostat at 100 ° C. and reacted for about 15 minutes. 20 g of dodecylamine (boiling point: 249 ° C.) was added thereto and reacted at the same temperature for 15 minutes.

In order to replace the dispersion medium of the suspension after the reaction, 10 ml of methanol was added to the suspension, followed by stirring. Then, silver fine particles B were precipitated and separated by centrifugation, and the supernatant was discarded. 10 ml of methanol was again added to the separated silver fine particles B, and the mixture was stirred and centrifuged to precipitate and separate the silver fine particles B.

<Preparation of bonding composition>
1 g of each of the obtained silver fine particles A and silver fine particles B was measured, and 0.1 g of hexyl carbitol, 0.1 g of butyl carbitol acetate, and 0.01 g of linoseal acid were added thereto as a dispersion medium, followed by stirring and mixing. A bonding composition was obtained.

The following items were evaluated for the bonding composition obtained as described above.

[Evaluation test]
(1) Measurement of Average Particle Size of Primary Particles Photograph of the average particle diameter of the primary particles of the obtained silver fine particles A and silver fine particles B taken with a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation). Then, the particle diameter of about 200 randomly selected primary particles was measured and calculated using image processing software WinROOF (manufactured by Mitani Corporation).
The results obtained are shown in Table 1 below.

(2) Measurement of bonding strength The obtained bonding composition was applied to a 6 mm square using a metal mask on a pure oxygen-free copper plate (20 mm square), and was dried in an oven set at 70 ° C for 30 minutes as preliminary drying. I let it. A gold-plated Si chip (bottom area 5 mm × 5 mm) was laminated on the dried bonding composition and pressed at 0.2 MPa.

The obtained laminate was placed in a reflow furnace (manufactured by Shin Apex Co., Ltd.), and nitrogen was flowed. When the oxygen concentration reached 300 ppm, the temperature was raised from room temperature to a maximum temperature of 275 ° C. at a rate of 3.8 ° C./min. After that, it was kept for 60 minutes to perform a baking treatment. At the time of the calcination treatment, no pressure was applied and the addition was performed without addition, and nitrogen was kept flowing. After natural cooling, the laminate was taken out.

The obtained laminate was subjected to a bonding strength test at room temperature using a 100 kgf load cell bond tester (manufactured by Resca Corporation). In the case of a 5 mm square chip and a 100 kgf load cell, the upper limit of the bonding strength is 40 MPa.
The results obtained are shown in Table 1 below.

(3) Thermal reliability test (-40 ° C / 200 ° C heat cycle test)
The obtained bonding composition is applied to an 11 mm square using a metal mask on a pure oxygen-free silicon nitride copper-clad substrate (30 mm × 40 mm), and placed in an oven set at 70 ° C. for preliminary drying for 30 minutes. Let dry. A gold-plated Si chip (bottom area 10 mm × 10 mm) was laminated on the dried bonding composition, and pressed at 0.2 MPa.

The obtained laminate was put into a reflow furnace (manufactured by Shin Apex Co., Ltd.), and nitrogen was flowed. When the oxygen concentration reached 300 ppm, the temperature was raised from room temperature to a maximum temperature of 275 ° C. at a rate of 3.8 ° C./min. After that, it was kept for 60 minutes to perform a baking treatment. At the time of the calcination treatment, no pressure was applied and the addition was performed without addition, and nitrogen was kept flowing. After natural cooling, the laminate was taken out.

The obtained laminate was placed in a thermal shock tester (manufactured by Hutec Co., Ltd.), and cycles of keeping at -40 ° C. and 200 ° C. for 10 minutes in an air atmosphere were taken out at an arbitrary number of cycles. “X” when the void ratio increased by 50% or more with respect to 0 cycle after 1000 cycles was “X”, and when the void ratio increased more than 10% and less than 50% was “Δ”, it was judged that the increase was 10% or less and did not change. When it was possible, it was judged as "〇". The results obtained are shown in Table 1 below.

The void fraction was evaluated with an ultrasonic flaw detector (probe 80 MHz, φ3 mm, PF = 10 mm) manufactured by Nippon Clout Kramer Co., Ltd. Fine adjustment was made so that the reflection peak at the bonding interface became the highest, and the measurement was performed with the material sound velocity = Si: 9600 mm / s.

(4) Measurement of porosity The bonded portion of the laminate before the heat resistance test prepared in the above (3) was polished, and a cross section was formed by ion milling. Thereafter, the cross section was observed with a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation). The porosity was calculated by dividing the area of the voids of the layer where the bonding composition was sintered by the total area of the layer where the bonding composition was sintered from the electron micrograph of the cross-sectional observation (image processing software WinROOF ( MITANI CORPORATION). "〇" when the porosity is 10% or less, "△" when the porosity is 11 to 20%, when the porosity is 20% or more, and when a large void exists or the bonded interface is peeled off. Those who do are marked "x".
The results obtained are shown in Table 1 below.

(Example 2)
Except that the amounts of silver fine particles A and silver fine particles B used in the preparation of the bonding composition were changed to 0.8 g for silver fine particles A and 1.2 g for silver fine particles B, the composition for bonding was the same as in Example 1. The product was prepared and the same evaluation test as in Example 1 was performed. The results obtained are shown in Table 1 below.

(Example 3)
The composition for bonding was the same as in Example 1 except that the amounts of the silver fine particles A and the silver fine particles B used in the preparation of the bonding composition were changed to 1.2 g for the silver fine particles A and 0.8 g for the silver fine particles B. The product was prepared and the same evaluation test as in Example 1 was performed. The results obtained are shown in Table 1 below.

(Example 4)
A bonding composition was prepared in the same manner as in Example 1 except that the amount of diglycolamine used in the preparation of silver fine particles B was changed from 6.0 g to 10.0 g, and the same evaluation test as in Example 1 was performed. . The results obtained are shown in Table 1 below.

(Example 5)
The amount of 3-methoxypropylamine used in the preparation of silver fine particles A was changed from 3.0 g to 9.0 g, and the amount of diglycolamine used in the preparation of silver fine particles B was changed from 6.0 g to 10.0 g. A bonding composition was prepared in the same manner as in Example 1 except that the amounts of silver fine particles A and silver fine particles B used in the preparation of the composition were changed to 1.4 g for silver fine particles A and 0.6 g for silver fine particles B. It was prepared and subjected to the same evaluation test as in Example 1. The results obtained are shown in Table 1 below.

(Example 6)
The dodecylamine used in the preparation of the silver fine particles A and the silver fine particles B was changed to octylamine (boiling point: 176 ° C.), and the dispersion medium used in the preparation of the bonding composition was 0.05 g of hexyl carbitol, butyl carbitol acetate Except having changed to 0.05 g and ricinoleic acid 0.005 g, it carried out similarly to Example 1, and obtained the composition for joining. An evaluation test was performed in the same manner as in Example 1 except that preliminary drying at 70 ° C. was not performed in the production of the laminate in the evaluation tests (2) and (3). The results obtained are shown in Table 1 below.

(Example 7)
The dodecylamine used in the preparation of the silver fine particles A and the silver fine particles B was changed to octylamine (boiling point: 176 ° C.), and the amounts of the silver fine particles A and the silver fine particles B used in the preparation of the bonding composition were changed. Example 5 except that 1.0 g, the silver fine particles B were changed to 1.0 g, and the dispersion medium was changed to 0.05 g of hexyl carbitol, 0.05 g of butyl carbitol acetate, and 0.005 g of ricinoleic acid. Similarly, a bonding composition was obtained. The evaluation test was performed in the same manner as in Example 5 except that the preliminary drying at 70 ° C. was not performed in the production of the laminate in the evaluation tests (2) and (3). The results obtained are shown in Table 1 below.

(Example 8)
The dodecylamine used in the preparation of the silver fine particles A and the silver fine particles B was not added, and the amounts of the silver fine particles A and the silver fine particles B used in the preparation of the bonding composition were as follows. Except that the fine particles B were changed to 0.8 g and the dispersion medium was changed to 0.05 g of hexyl carbitol, 0.05 g of butyl carbitol acetate, and 0.005 g of ricinoleic acid, the same procedure as in Example 5 was carried out. A composition was obtained. The evaluation test was performed in the same manner as in Example 5 except that the preliminary drying at 70 ° C. was not performed in the production of the laminate in the evaluation tests (2) and (3). The results obtained are shown in Table 1 below.

(Example 9)
A bonding composition was obtained in the same manner as in Example 1, except that dodecylamine (boiling point: 176 ° C.) was used in the preparation of silver fine particles A and silver fine particles B. An evaluation test was performed in the same manner as in Example 1. The results obtained are shown in Table 1 below.

(Comparative Example 1)
A bonding composition was prepared in the same manner as in Example 1 except that the silver fine particles A used in the preparation of the bonding composition were not added and the amount of the silver fine particles B was changed to 2.0 g. The evaluation was performed in the same manner as described above. The results obtained are shown in Table 2 below.

(Comparative Example 2)
Example 1 A bonding composition was prepared in the same manner as in Example 1 except that the silver fine particles B used in the preparation of the bonding composition were not added and the amount of the silver fine particles A was changed to 2.0 g. The evaluation was performed in the same manner as described above. The results obtained are shown in Table 2 below.

(Comparative Example 3)
<Preparation of silver fine particles A>
While sufficiently stirring 2.0 g of 3-methoxypropylamine (boiling point: 116 ° C.) and 2.0 g of diglycolamine with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put in a thermostat at 100 ° C. and reacted for about 15 minutes. In order to replace the dispersion medium of the suspension after the reaction, 10 ml of methanol was added to the suspension, followed by stirring. Then, silver fine particles A were precipitated and separated by centrifugation, and the supernatant was discarded. 10 ml of methanol was again added to the separated silver fine particles A, and the mixture was stirred and centrifuged to precipitate and separate the silver fine particles A.

<Preparation of bonding composition>
2 g of the obtained silver fine particles A were measured and added thereto, and 0.05 g of hexyl carbitol, 0.05 g of butyl carbitol acetate, and 0.005 g of ricinoleic acid were added thereto as a dispersion medium, followed by stirring and mixing to obtain a bonding composition. Was.

The evaluation test was performed in the same manner as in Example 1 except that the preliminary drying at 70 ° C. was not performed in the production of the laminate in the evaluation tests (2) and (3). The results obtained are shown in Table 2 below.

(Comparative Example 4)
In the preparation of the bonding composition, a bonding composition was prepared in the same manner as in Example 3 except that micro silver particles (average particle size: 2.5 μm) manufactured by Fukuda Metal Foil Powder Co., Ltd. were used as the silver fine particles B. Evaluation was performed in the same manner as in Example 3. The results obtained are shown in Table 2 below.

(Comparative Example 5)
<Preparation of silver fine particles A>
While sufficiently stirring 3.0 g of 3-methoxypropylamine (boiling point: 116 ° C.) with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put in a thermostat at 100 ° C. and reacted for about 15 minutes. Further, 10 g of levulinic acid was added thereto and reacted at the same temperature for 15 minutes. In order to replace the dispersion medium of the suspension after the reaction, 10 ml of methanol was added to the suspension, followed by stirring. Then, silver fine particles A were precipitated and separated by centrifugation, and the supernatant was discarded. 10 ml of methanol was again added to the separated silver fine particles A, and the mixture was stirred and centrifuged to precipitate and separate the silver fine particles A. The obtained silver fine particles A were coated with levulinic acid, and were not coated with 3-methoxypropylamine.

<Preparation of silver fine particles B>
While sufficiently stirring 6.0 g of diglycolamine with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put in a thermostat at 100 ° C. and reacted for about 15 minutes. In order to replace the dispersion medium of the suspension after the reaction, 10 ml of methanol was added to the suspension, followed by stirring. Then, silver fine particles B were precipitated and separated by centrifugation, and the supernatant was discarded. 10 ml of methanol was again added to the separated silver fine particles B, and the mixture was stirred and centrifuged to precipitate and separate the silver fine particles B.

<Preparation of bonding composition>
0.8 g of the obtained silver fine particles A and 1.2 g of the silver fine particles B were measured, and 0.1 g of hexyl carbitol, 0.1 g of butyl carbitol acetate, and 0.01 g of ricinoleic acid were added thereto as a dispersion medium. The mixture was stirred and mixed to obtain a bonding composition.
An evaluation test was performed on the obtained bonding composition in the same manner as in Example 1. The results obtained are shown in Table 2 below.

(Comparative Example 6)
<Preparation of silver fine particles A>
3.0 g of silver oxalate was added while sufficiently stirring 3.0 g of 3-methoxypropylamine (boiling point: 116 ° C.) and 20 g of dodecylamine (boiling point: 249 ° C.) with a magnetic stirrer to increase the viscosity. The obtained viscous substance was put in a thermostat at 100 ° C. and reacted for about 15 minutes. In order to replace the dispersion medium of the suspension after the reaction, 10 ml of methanol was added to the suspension, followed by stirring. Then, silver fine particles A were precipitated and separated by centrifugation, and the supernatant was discarded. 10 ml of methanol was again added to the separated silver fine particles A, and the mixture was stirred and centrifuged to precipitate and separate the silver fine particles A.

<Preparation of silver fine particles B>
3.0 g of silver oxalate was sufficiently stirred with 5.0 g of 3-methoxypropylamine (boiling point: 116 ° C.), 0.5 g of dodecylamine (boiling point: 249 ° C.), and 6.0 g of diglycolamine with a magnetic stirrer. Was added to increase the viscosity. The obtained viscous substance was put in a thermostat at 100 ° C. and reacted for about 15 minutes. In order to replace the dispersion medium of the suspension after the reaction, 10 ml of methanol was added to the suspension, followed by stirring. Then, silver fine particles B were precipitated and separated by centrifugation, and the supernatant was discarded. 10 ml of methanol was again added to the separated silver fine particles B, and the mixture was stirred and centrifuged to precipitate and separate the silver fine particles B.

<Preparation of bonding composition>
1.0 g of each of the obtained silver fine particles A and silver fine particles B was measured, and 0.1 g of hexyl carbitol, 0.1 g of butyl carbitol acetate, and 0.01 g of ricinoleic acid were added thereto as a dispersion medium, followed by stirring. By mixing, a bonding composition was obtained.
An evaluation test was performed on the obtained bonding composition in the same manner as in Example 1. The results obtained are shown in Table 2 below.

(Comparative Example 7)
In the preparation of the bonding composition, a bonding composition was prepared in the same manner as in Example 1 except that ricinoleic acid was not added as a dispersion medium, and an evaluation test was performed in the same manner as in Example 1. The results obtained are shown in Table 2 below.

(Example 10)
Except that the amounts of silver fine particles A and silver fine particles B used in the preparation of the bonding composition were changed to 0.8 g of silver fine particles A and 1.2 g of silver fine particles B, the bonding composition was prepared in the same manner as in Example 8. Obtained. An evaluation test was performed in the same manner as in Example 8. The results obtained are shown in Table 3 below.

(Example 11)
As the silver fine particles B, those prepared by adding the dodecylamine in the preparation method of the silver fine particles B in Example 1 were used, and the dispersion medium was 2-ethyl-1,3-hexanediol 0.05 g, butyl A bonding composition was obtained in the same manner as in Example 10, except that carbitol acetate was changed to 0.05 g and ricinoleic acid to 0.005 g. An evaluation test was performed in the same manner as in Example 10. The results obtained are shown in Table 3 below.

(Example 12)
As the silver fine particles B, those prepared in the preparation method of the silver fine particles B of Example 1 without adding dodecylamine were used, and the amounts of the silver fine particles A and the silver fine particles B used in the preparation of the bonding composition Was changed to 0.4 g of silver fine particles A and 1.6 g of silver fine particles B in the same manner as in Example 8 to obtain a bonding composition. An evaluation test was performed in the same manner as in Example 8. The results obtained are shown in Table 3 below.

From the results of Tables 1 to 3 above, it is found that silver fine particles A coated with a specific primary amine and having an average particle size of 45 to 75 nm, and coated with a specific primary amine and having an average particle size of 45 to 75 nm. Examples 1 to 12 containing silver fine particles B of 200 to 550 nm and further containing an unsaturated hydrocarbon (ricinoleic acid) as a dispersion medium have high bonding strength of 40 MPa or more and a porosity of 10% or less. A high-density bonding layer was formed, and the heat resistance was sufficiently high.

On the other hand, the bonding compositions according to Comparative Examples 1 to 4 in which the particle diameter of the silver fine particles does not satisfy the combination in the specific range are inferior in any of the bonding strength, the porosity, and the heat resistance reliability. No joining composition was obtained.

In addition, the bonding composition according to Comparative Example 5 using silver fine particles A and B not coated with a specific primary amine as silver fine particles is inferior in any of bonding strength, porosity, and heat resistance reliability. Was something.

Further, the bonding composition according to Comparative Example 6 partially contained a specific primary amine as silver fine particles, but the complex compound before heating varied depending on the content thereof. The diameter has become smaller. Therefore, the bonding composition according to Comparative Example 6 was inferior in all of the bonding strength, porosity, and heat resistance reliability.

The bonding composition according to Comparative Example 7 containing no unsaturated hydrocarbon (ricinoleic acid) in the dispersion medium was inferior in all of the bonding strength, the porosity, and the heat resistance reliability.

Claims

A bonding composition containing silver fine particles coated with a primary amine and a dispersion medium,
The primary amine has 4 to 12 carbon atoms and a boiling point of 300 ° C. or less;
The silver fine particles include first silver fine particles having an average particle size of 45 to 75 nm, and second silver fine particles having an average particle size of 200 to 550 nm,
The joining composition, wherein the dispersion medium contains an unsaturated hydrocarbon.
The bonding composition according to claim 1, wherein the second silver fine particles are formed from a silver complex compound different from the first silver fine particles.
3. The bonding composition according to claim 1, wherein a weight ratio of the first silver fine particles to the second silver fine particles is from 4: 6 to 7: 3.
4. The bonding composition according to claim 1, wherein the dispersion medium contains at least an organic solvent having a hydroxyl group.
The bonding composition according to any one of claims 1 to 4, wherein the unsaturated hydrocarbon is ricinoleic acid.
The bonding composition according to any one of claims 1 to 5, wherein the composition does not contain a polymer dispersant.
The bonding composition according to any one of claims 1 to 6, wherein a porosity of a bonding layer obtained by heating and baking the bonding composition at 275 ° C is 10% or less.