JP7740441B2 - Metal particle-containing composition, bonding paste, and bonded body - Google Patents

Description

The present invention relates to a metal particle-containing composition, a bonding paste, and a bonded body.

Conventionally, solder has been used as a bonding material for bonding metal components together, between metal components and semiconductor elements, between metal components and light-emitting diode (LED) elements, etc. In recent years, the field of next-generation power electronics has seen a demand for devices such as SiC that can operate at high temperatures. As bonding materials for manufacturing such devices, alternative materials to solder are needed from the perspective of high-temperature operating reliability. For example, as shown in Patent Documents 1 to 3, bonding materials such as bonding pastes using sinterable metal particles have been proposed.

Patent Document 1 discloses a bonding material containing metal submicron particles with an average primary particle size of 0.5 to 3.0 μm and metal nanoparticles with an average primary particle size of 1 to 200 nm that are coated with an organic compound containing 6 to 8 carbon atoms. However, there was a problem in that the bonding strength at the bonded portion was poor, and the bonding strength decreased with thermal cycling.

Patent Document 2 discloses a bonding material containing silver nanoparticles with an average primary particle size of 1 to 200 nm that are coated with an organic substance having 8 or fewer carbon atoms, and a flux component having at least two carboxyl groups. Furthermore, Patent Document 3 discloses a bonding material containing silver microparticles with an average primary particle size of 130 nm or less and a cross-linked interparticle distance-maintaining agent that maintains the distance between the silver microparticles.

However, even with these bonding materials, similar to the technology disclosed in Patent Document 1, there was a problem in that the bonded area lacked strength and the bond strength decreased with thermal cycling. Furthermore, when a bonding paste containing a high concentration of silver nanoparticles was created to achieve a dense and strong bond, it also had the drawback of significantly reducing fluidity. As a result, during the process of printing the bonding paste onto the bonded parts, there were problems with the printed areas becoming faded and uncoated areas being formed.

JP 2011-80147 A JP 2011-240406 A Japanese Patent Application Laid-Open No. 2018-109232

The properties required for bonding pastes using metal particles include printability on the parts to be bonded, sufficient bonding strength, and minimal loss of bonding strength after reliability tests such as thermal cycling.

Therefore, the problem that the present invention aims to solve is to provide a metal particle-containing composition that provides high bonding strength at the bonded portion and suppresses a decrease in bonding strength due to thermal cycling. Furthermore, in addition to the above properties, the present invention aims to provide a bonding paste that has excellent printability on the bonded body even when it contains a high concentration of metal particles. Furthermore, the present invention aims to provide a bonded body that does not deteriorate due to thermal cycling.

The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention.
That is, the present invention relates to a metal particle-containing composition comprising metal particles (A) having an average particle size of 180 nm to 1000 nm and a compound (B) having 20 to 80 carbon atoms and having two or more functional groups (b), each of which is one selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group.

The present invention also relates to the metal particle-containing composition in which the number of functional groups is 2 or 3.

The present invention also relates to the metal particle-containing composition, wherein the compound (B) has a branched and/or cyclic structure.

The present invention also relates to the metal particle-containing composition, in which the compound (B) has an n-valent hydrocarbon group, where n is the number of functional groups.

The present invention also relates to the metal particle-containing composition, in which the n-valent hydrocarbon group has 30 to 60 carbon atoms.

The present invention also relates to the metal particle-containing composition, wherein the compound (B) comprises one or more compounds selected from the group consisting of dimer acid, trimer acid, dimer diol, trimer triol, dimer diamine, and trimer triamine.

The present invention also relates to the metal particle-containing composition, which contains 0.1 to 3 parts by mass of the compound (B) per 100 parts by mass of the metal particles (A).

The present invention also relates to the metal particle-containing composition, which contains 0.3 to 2.5 parts by mass of the compound (B) per 100 parts by mass of the metal particles (A).

The present invention also relates to the metal particle-containing composition, wherein the average particle diameter of the metal particles (A) is 200 nm to 400 nm.

The present invention also relates to a joining paste containing a dispersion medium (C) and the above-mentioned metal particle-containing composition.

The present invention also relates to the above-mentioned joining paste, in which the mass of the metal particles (A) is 80% by mass to 95% by mass of the sum of the masses of the metal particles (A), the compound (B), and the dispersion medium (C).

The present invention also relates to a bonded body in which a first bonded part and a second bonded part are bonded using the above-mentioned bonding paste.

The present invention makes it possible to provide a metal particle-containing composition that provides high bonding strength at the bonded portion and does not lose bonding strength due to thermal cycling. In addition to these effects, it also makes it possible to provide a bonding paste that has excellent printability. Furthermore, it makes it possible to provide a bonded body that does not deteriorate due to thermal cycling.

In this specification, "metal particles (A) having an average particle size of 180 nm to 1000 nm" is referred to as "
The term "metal particles (A)" and "compound (B) having 20 to 80 carbon atoms and having a plurality of identical functional groups in the molecule" may be abbreviated as "compound (B)."

The metal particle-containing composition of the present invention contains metal particles (A) and a compound (B). The joining paste also contains a dispersion medium (C) in addition to the metal particles (A) and compound (B). The metal particle-containing composition may be formed by volatilizing some or all of the dispersion medium (C) from the joining paste during the joining process.

(Metal particles (A))
Examples of the metal in the metal particles (A) include gold, silver, copper, nickel, chromium, palladium, rhodium, ruthenium, indium, silicon, aluminum, tungsten, molybdenum, platinum, and alloys thereof.Furthermore, fine particles coated with a material different from the core material and the core material can be mentioned, specifically, for example, silver-coated copper powder, which uses copper as the core and coats its surface with silver.Other examples include powders of metal oxides such as silver oxide, indium oxide, tin oxide, zinc oxide, ruthenium oxide, ITO (tin-doped indium oxide), AZO (aluminum-doped zinc oxide), and GZO (gallium-doped zinc oxide), as well as powders surface-coated with these metal oxides.The type of metal used can be one type, or two or more types can be used in combination.

The metal particles (A) are preferably selected from copper or silver, as this produces a bonded body with particularly excellent strength. Furthermore, the metal particles (A) are more preferably silver, as this can be used at a wide range of firing temperatures and in various firing environments, such as atmospheric pressure, a nitrogen atmosphere, a vacuum, or a reducing atmosphere.

The metal particles (A) have a specific average particle size range, which allows them to melt or bond together (hereinafter also referred to as sintering) at temperatures between 200°C and 350°C, when the metal particle-containing composition or joining paste is heated and sintered, and turn into bulk metal. As a result, the objects to be joined are joined. Hereinafter, the region formed by sintering the metal particles (A) between the objects to be joined is referred to as the joining layer.

In the present invention, it is important to use metal particles (A) having a specific average particle size. As used herein, "average particle size" refers to the 50% cumulative particle size distribution particle size (d50) on a volume basis determined by the measurement method described in the Examples. The d50 of metal particles (A) is 180 to 1,000 nm, preferably 200 to 400 nm, and more preferably 200 to 300 nm.

The surfaces of the metal particles (A) are preferably coated with an organic component (a). Coating with the organic component (a) is expected to improve the storage stability of the metal particle-containing composition and bonding paste. Examples of the organic component (a) include fatty acids, aliphatic amines, and aliphatic alcohols. Saturated or unsaturated fatty acids are preferred, saturated or unsaturated fatty acids with 3 to 18 carbon atoms are more preferred, and saturated or unsaturated fatty acids with 6 to 18 carbon atoms are even more preferred. One or more types of organic component (a) may be included.

Metal particles (A) may be used alone or in combination. If necessary, metal particles other than metal particles (A) may be used in combination. When metal particles other than metal particles (A) are used in combination, it is preferable to use metal particles with an average particle size of more than 1000 nm.

<Compound (B)>
Next, the compound (B) will be described. Generally, since metal particles are powder, when the compound (B) is not contained, as the dispersion medium volatilizes from the bonding paste, it becomes difficult to form an interface with the bonded parts. However, when the compound (B) of the present invention is present, the bonding paste can behave as a liquid metal particle-containing composition even after a part or all of the dispersion medium (C) has volatilized, so that it is easy to form a good bonding interface that is integrated with the bonded parts.

Compound (B) has two or more functional groups selected from hydroxyl groups, carboxyl groups, and amino groups (hereinafter, these functional groups will be referred to as "functional groups (b)") within the molecule, and has a structure containing 20 to 80 carbon atoms.

The number of carbon atoms in compound (B) includes the number of carbon atoms in functional group (b). Therefore, if functional group (b) in compound (B) is a carboxy group, the number of carbon atoms in compound (B) is considered to include the number of carbon atoms in this carboxy group.

In compound (B), the skeleton (partial structure) excluding functional group (b) is an organic residue, but is preferably a hydrocarbon group or a group in which multiple hydrocarbon groups are linked by a linking group containing a heteroatom. Examples of such linking groups containing a heteroatom include an -O- group (ether group), a -C(=O)- group (carbonyl group), a -C(=O)-O- group (also referred to as an ester group or oxycarbonyl group), and a -C(=O)-NH- group (also referred to as an amide group or iminocarbonyl group). It is preferable that compound (B) does not have any functional groups other than functional group (b).

The state of compound (B) is not particularly limited, but it is preferably liquid at 200°C to 350°C, the temperature range in which the metal particle-containing composition of the present invention is fired. Compound (B) may be solid or liquid at room temperature (25°C), but it is more preferably liquid at room temperature so that it can be uniformly dispersed in the metal particle-containing composition and act effectively.

If compound (B) has the property of being liquid in the above temperature range, it is expected that the wettability at the bonding interface with the bonded parts will increase, and the contact area will increase. As a result, it will be possible to produce a bonded body with a strong bonding interface. Furthermore, even if voids form in the bonding layer during sintering, the increased fluidity of the metal particle-containing composition will allow liquid compound (B) to flow into defects such as voids, making it possible to obtain a bonding layer and bonded body with fewer defects.

The number of functional groups (b) in compound (B) is preferably 2 or 3.

Compound (B) may have a linear structure or a branched and/or cyclic structure, but preferably has a branched and/or cyclic structure. Compounds having a branched and/or cyclic structure are preferred because they tend to have low crystallinity and become liquid with good fluidity.

When the number of functional groups (b) in compound (B) is n, compound (B) preferably has an n-valent hydrocarbon group. In compound (B), the skeleton excluding functional groups (b) preferably consists solely of n-valent hydrocarbon groups, as this allows for the formation of a strong bonded structure.

For the above reasons, it is preferable that compound (B) does not evaporate immediately when sintering begins, but it does not necessarily have to remain in the formed bonding layer when sintering is completed. When the carbon number of the n-valent hydrocarbon group is 30 to 60, the amount of compound (B) remaining in the bonding layer after sintering can be further reduced, making it easier to obtain a denser bonding layer, which is preferable. As a result, excellent initial bonding strength can be achieved, and further suppression of deterioration in bonding strength due to thermal cycling can be expected.

Specific examples of compound (B) with a linear structure include, but are not limited to, eicosane diacid, heneicosane diacid, docosane diacid, tetracosane diacid, triacontanedioic acid, dotriacontanedioic acid, tetracontanedioic acid, pentacontanedioic acid, hexacontanedioic acid, and batyl alcohol.

Furthermore, examples of branched and/or cyclic structures include, but are not limited to, dimer acid, trimer acid, tetramer acid, dimer diol, trimer triol, tetramer tetraol, dimer diamine, trimer triamine, tetramer tetramine, phytantriol, etc.

Among these specific examples, compound (B) is more preferably selected from dimer acid, trimer acid, dimer diol, trimer triol, dimer diamine, and trimer triamine, for the reasons mentioned above.

Dimer acid, trimer acid, and tetramer acid can be produced by the polymerization reaction of unsaturated fatty acids. For example, they can be produced by the Diels-Alder reaction of oleic acid (18 carbon atoms) and linoleic acid (18 carbon atoms) or by radical reaction. Dimer acid, trimer acid, and tetramer acid preferably have 36, 54, and 72 carbon atoms, respectively. Furthermore, by appropriately changing the carbon number of the unsaturated fatty acid used as the raw material, it is possible to produce compound (B) having a carbon number other than those listed above. In this specification, dimers, trimers, and tetramers of unsaturated fatty acids having 12 or more carbon atoms are referred to as dimer acid, trimer acid, and tetramer acid, respectively.

Dimer diol, trimer triol, and tetramer tetraol each have a structure in which the carboxy group of a dimer acid has been reduced to a hydroxyl group. The carboxy group of a trimer acid, trimer triol, and tetramer tetraol each have a structure in which the carboxy group of a tetramer acid has been reduced to a hydroxyl group. Dimer diol, trimer triol, and tetramer tetraol preferably have 36, 54, and 72 carbon atoms, respectively.

Dimer diamine has a structure in which the carboxy group of dimer acid has been functionally converted to an amino group, while trimer triamine has a structure in which the carboxy group of trimer acid has been functionally converted to an amino group. Dimer diamine, trimer triamine, and tetramer tetramine preferably have 36, 54, and 72 carbon atoms, respectively.

Due to the manufacturing process, compound (B) may be a mixture of compounds with different degrees of polymerization, but it may be used as a mixture of different polymerizations, or as a specific single compound.

In the metal particle-containing composition of the present invention, compound (B) is preferably contained in an amount of 0.1 to 3 parts by mass, and more preferably 0.3 to 2.5 parts by mass, per 100 parts by mass of metal particles (A). This range makes it possible to obtain a bonded body that exhibits particularly excellent initial bond strength and that is inhibited from decreasing in bond strength due to thermal cycling.

The bonding paste of the present invention contains a dispersion medium (C). The dispersion medium (C) serves to disperse the metal particles (A) and the compound (B).

The dispersion medium (C) may be any medium capable of uniformly dispersing the metal particles (A) and the compound (B). Specific examples thereof include terpineol, dihydroterpineol, dihydroterpinyl acetate, Tersolve MTPH (manufactured by Nippon Terpen Co., Ltd.), and Texanol (2,2,4-
trimethylpentane-1,3-diol monoisobutyrate), carbitol, carbitol acetate, butyl carbitol, isophorone, γ-butyl lactone, dipropylene glycol monomethyl ether, dipropylene glycol methyl-n-propyl ether, 3-methoxy-3-methylbutyl acetate, ethylene glycol, hexanoic acid, propylene glycol diacetate, dipropylene glycol methyl ether acetate, 1,3-butylene glycol, isoparaffin solvents contained in hydrocarbon solvents, and the like, but are not limited to these.

Of these dispersion media (C), terpineol, dihydroterpineol, Tersolve MTPH, Texanol, carbitol, carbitol acetate, butyl carbitol, isophorone, γ-butyl lactone, dipropylene glycol monomethyl ether, and isoparaffin-based solvents are more preferably used. These dispersion media (C) can be used alone or in combination.

When sintering the joining paste, it is preferable for the boiling point of the dispersion medium (C) to be lower than the boiling point of the compound (B), since this reduces the amount of dispersion medium (C) coexisting with the metal particle-containing composition during sintering, thereby increasing the content of metal particles (A).

By using a combination of metal particles (A) and compound (B), the bonding paste of the present invention has excellent fluidity and is therefore highly suitable for printing on the bonded bodies, even when it contains a high concentration of metal particles (A), i.e., when the content of dispersion medium (C) is low. As a result, it is possible to obtain a stronger bonded body with fewer defects.

In the bonding paste, the mass ratio of metal particles (A) to the sum of the masses of metal particles (A), compound (B), and dispersion medium (C) is preferably 80% to 95% by mass, and more preferably 85% to 94% by mass. By including components in this range, good printability of the bonding paste can be ensured, and residual dispersion medium (C) in the bonded body can be suppressed, suppressing the occurrence of voids originating from the dispersion medium (C), and achieving good bonding strength.

The joining paste of the present invention may contain additives, such as sintering accelerators, binder resins, or resin-type dispersants.

Devices used to prepare the joining paste from metal particles (A), compound (B), and dispersion medium (C) include a disperser, a three-roll mill, a bead mill, an ultrasonic disperser, and a planetary stirrer.

The joining paste of the present invention can be used to join a first part to be joined and a second part to be joined to obtain a joined body.

The method for applying the bonding paste to the objects to be bonded is not particularly limited, as long as it allows for uniform application to the components. Examples include various printing methods such as screen printing, flexographic printing, offset printing, gravure printing, metal mask printing, and gravure offset printing, as well as dispensing methods using a dispenser. The bonding paste of the present invention has excellent fluidity even when it contains a high concentration of metal particles, so it is particularly preferable to use it in combination with metal mask printing.

When placing the second part to be joined on the first part to which the joining paste of the present invention has been applied, the second part to be joined can be placed under pressure. The pressure is appropriately set depending on the viscosity of the joining paste and the drying state of the paste, but is preferably 0.1 to 40 MPa, more preferably 0.3 to 30 MPa.

The sintering conditions for joining a laminate consisting of a first bonded portion and a second bonded portion may be varied as appropriate, but examples include atmospheric pressure, a nitrogen atmosphere, a vacuum, or a reducing atmosphere at 200 to 350°C. Sintering devices include hot air ovens, infrared ovens, reflow ovens, microwave ovens, hot plates, and optical sintering devices. These devices may be used alone or in combination as appropriate. Pressure may also be applied during sintering. The pressure is set as appropriate depending on the viscosity of the bonding paste and the drying state of the paste, but is preferably 0.1 to 40 MPa, and more preferably 0.3 to 30 MPa.

Before the baking process, a preliminary drying process can be carried out as needed to remove any organic components from the bonding coating. For example, this can be done using a similar device to the baking device, at temperatures between 60 and 220°C.

A preferred method for joining two parts to be joined is to apply the joining paste of the present invention to the first part to be joined, place the second part to be joined on top, and then heat the mixture to approximately 300°C at a rate of approximately 2°C/min to sinter it. After the temperature increase is complete, it is preferable to maintain the mixture at a temperature higher than the temperature at the end of the temperature increase for approximately 10 minutes to 2 hours.

The type of part to be joined is not particularly limited, and examples include metal materials, semiconductor materials, plastic materials, ceramic materials, etc. Electronic elements are also examples.

Examples of metals include copper, gold, and aluminum.
Examples of semiconductor materials include silicon, germanium, gallium arsenide, gallium phosphide, cadmium sulfide, silicon nitride, graphite, yttrium oxide, magnesium oxide, silicon carbide, and gallium nitride.
Examples of the plastic material include polyimide, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate.
Examples of ceramic materials include glass and silicon.

Furthermore, examples of electronic elements include semiconductor elements, LED elements, power device elements, etc.

The first and second parts to be joined do not have to be the same type of material, but may be different types of materials. The surfaces of the parts to be joined may be treated with corona treatment, plating, etc. to increase the joining strength of the joined area.

There is no limit to the thickness of the bonding layer formed when bonding parts using the metal particle-containing composition or bonding paste of the present invention, but it is preferably 3 μm to 500 μm, more preferably 10 μm to 200 μm, and even more preferably 20 μm to 100 μm.

The present invention will be explained in detail below using examples and comparative examples, but the technical scope of the present invention is not limited to these. In the examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass," and numerical values in tables mean "parts" unless otherwise specified.

(Production Example 1) Metal particles A1
Under a nitrogen atmosphere, 200 parts of toluene and 22.3 parts of silver hexanoate were mixed with stirring at 25°C to form a 0.5M solution, and then 1.6 parts of diethylaminoethanol and 0.28 parts of oleic acid were added as dispersants and dissolved. Subsequently, 73.1 parts of a 20% aqueous solution of succinic acid dihydrazide (hereinafter referred to as SUDH) was added dropwise as a reducing agent, causing the liquid color to change from pale yellow to dark brown. To further promote the reaction, the temperature was raised to 40°C, and the reaction was allowed to proceed. After allowing to stand and separating, the aqueous phase was removed to remove excess reducing agent and impurities. Distilled water was added to the toluene layer several times, followed by repeated washing and separation. This process of adding toluene, centrifuging, and removing the supernatant was repeated twice. The precipitate was dried to obtain metal particles A1 in which silver particles were coated with hexanoic acid and oleic acid. The particle diameter of metal particles A1 was determined using the method described below, and the d50 was found to be 210 nm.

(Production Example 2) Metal particles A2
Metal particles A2 were obtained in the same manner as in Production Example 1, except that the amount of diethylaminoethanol was 1.8 parts and the amount of oleic acid was 0.31 parts. The d50 was 185 nm.
(Production example 3) Metal particles A3
Metal particles A3 were obtained in the same manner as in Production Example 1, except that the amount of diethylaminoethanol was 1.2 parts and the amount of oleic acid was 0.18 parts. The d50 was 290 nm.
(Production Example 4) Metal particles A4
Metal particles A4 were obtained in the same manner as in Production Example 1, except that the amount of diethylaminoethanol was 1.0 part and the amount of oleic acid was 0.14 part. The d50 was 390 nm.

(Production Example 5) Metal particles A5
Metal particles A5 were obtained in the same manner as in Production Example 1, except that the amount of diethylaminoethanol was 0.6 parts and the amount of oleic acid was 0.070 parts. The d50 was 1100 nm.
(Production Example 6) Metal particles A6
Metal particles A6 were obtained in the same manner as in Production Example 1, except that the amount of diethylaminoethanol was 2.3 parts and the amount of oleic acid was 2.8 parts. The d50 was 20 nm.
(Production Example 7) Metal particles A7
Metal particles A7 were obtained in the same manner as in Production Example 1, except that the amount of diethylaminoethanol was 2.1 parts and the amount of oleic acid was 0.71 parts. The d50 was 85 nm. Of the metal particles produced by the above method, metal particles A1 to A4 correspond to metal particles (A), and metal particles A5 to A7 correspond to metal particles other than metal particles (A).

(Production Example 8) Trimer triol (Compound B4)
Trimer triol was synthesized as follows, with reference to the method described in JP-A-10-67835. Under a nitrogen atmosphere, 1,000 g of an unsaturated fatty acid ester mixture containing 75% methyl oleate, 15% methyl linoleate, and 9% methyl stearate was reacted with 70 g of activated clay in an autoclave at 230°C for 5 hours. The catalyst was filtered off from the reaction solution, and the mixture was distilled under reduced pressure to obtain 115 g of trimer acid trimethyl ester.
In a flask equipped with a dropping funnel, a condenser, a thermometer and a stirrer, 6.4 g of lithium aluminum hydride and 240 ml of diethyl ether were carefully mixed under a nitrogen atmosphere to prepare a dispersion of lithium aluminum hydride.
Under a nitrogen atmosphere, a solution prepared by diluting 50 g of trimer acid trimethyl ester with 70 ml of diethyl ether was added dropwise to the dispersion over 120 minutes while stirring. The reaction was allowed to proceed while maintaining the temperature at approximately 30°C or below. After the addition, the mixture was stirred for approximately 40 minutes. Then, 13 g of ion-exchanged water was carefully added dropwise while cooling to inactivate the excess reducing agent. The reaction solution was carefully transferred to a flask containing 70 g of ice water, and 50 g of 10% aqueous sulfuric acid solution was added. After allowing to stand for a while, an appropriate amount of diethyl ether was added to the flask to extract the product. The ether layer was repeatedly washed with water until neutral, and the diethyl ether was distilled off to obtain 31 g of a 54-carbon trimer triol consisting of three hydroxyl groups and a trivalent hydrocarbon group with branched and cyclic structures. The resulting trimer triol was a viscous liquid at 25°C.

[Measurement of particle size]
Isopropyl alcohol was added to each of the metal particles (A) and dispersed using an ultrasonic disperser to obtain a 0.5% by mass dispersion. The particle diameter of the metal particles (A) in the obtained dispersion was measured using a Nanotrac UPA-EX150 (manufactured by Nikkiso Co., Ltd.) to determine the average particle diameter (d50).

[Compound (B)]
The following materials were used as compounds (B) other than compound B4. However, compounds B8 and B9 are not compounds (B). The carbon number, material name, and properties at 25°C are written in parentheses. Compounds B1 to B3, B5, and B6 were manufactured by Croda Japan Co., Ltd., and reagents from Sigma-Aldrich were used for B7 to B9. The boiling points of compounds B1 to B7 are all 350°C or higher.

Compound B1: Pripol 1009 (a hydrogenated dimer acid having 36 carbon atoms, consisting of two carboxyl groups and a divalent hydrocarbon group having a branched and cyclic structure; liquid)
Compound B2: Pripol 1040 (a trimer acid having 54 carbon atoms, consisting of three carboxyl groups and a trivalent hydrocarbon group having a branched and cyclic structure; liquid)
Compound B3: Pripol 2033 (a dimer diol having 36 carbon atoms, consisting of two hydroxyl groups and a divalent hydrocarbon group having a branched and cyclic structure, liquid)
Compound B5: Priamine 1071 [a mixture of a C36 dimer triamine (liquid, consisting of two amino groups and a divalent hydrocarbon group having a branched and cyclic structure) and a C54 trimer triamine (liquid, consisting of three amino groups and a trivalent hydrocarbon group having a branched and cyclic structure)]
Compound B6: Priamine 1075 (a dimer diamine having 36 carbon atoms, consisting of two amino groups and a divalent hydrocarbon group having a branched and cyclic structure; liquid)
Compound B7: Docosanedioic acid (a linear dibasic acid having 22 carbon atoms, solid)
Compound B8: Oleic acid (a monovalent straight-chain fatty acid having 18 carbon atoms, liquid)
Compound B9: Malonic acid (a divalent straight-chain fatty acid having 3 carbon atoms, solid state)

[Dispersion medium (C)]
The following materials were used as the dispersion medium (C). The manufacturer's name, supplementary information, and boiling point are given in parentheses.
Dispersion medium C1: Dihydroterpineol (manufactured by Nippon Terpene Chemical Co., Ltd., boiling point 207°C)
Dispersion medium C2: Isobornylcyclohexanol (manufactured by Nippon Terpene Chemical Co., Ltd., boiling point 318°C)
Dispersion medium C3: Isopar L (manufactured by Ando Parachemie Co., Ltd., isoparaffin with a boiling point of 185 to 198°C)
Dispersion medium C4: Texanol (manufactured by Tokyo Chemical Industry Co., Ltd., reagent, boiling point 244°C)

[Example 1]
Metal particles A1 (92 parts), dihydroterpineol (8 parts), and compound B1 (1 part) were mixed using a rotary mixer to prepare a bonding paste. Then, a bonded body was produced and evaluated by the method described below. The results are shown in Table 1.

[Examples 2 to 32], [Comparative Examples 1 to 8]
A joining paste was obtained in the same manner as in Example 1, except that the type and amount of materials were changed according to the composition shown in Table 1, and then evaluated. The results are shown in Table 1. In Table 1, unless otherwise specified, the numerical values represent parts, and blank spaces indicate that no compound was added. However, Example 7 is a reference example.

[Preparation of Bonded Assembly]
Each bonding paste was printed once on the plated surface of the bonded part 1 described below under the printing conditions described below, and then the plated surface of the bonded part 2 (chip) described below was placed facing the bonding paste surface and heated under the sintering conditions described below to obtain each bonded body.
<Joined part 1>
Gold-plated copper substrate: 20 x 20 x 3 mm
<Joined part 2>
Gold-plated SiC chip: 5 x 5 x 0.3 mm
<Printing conditions (metal mask printing)>
Metal mask: 4 mm square opening, 50 μm thickness (manufactured by Ceria Corporation)
Metal squeegee: 40 mm x 250 mm, thickness 1 mm (manufactured by Seria Corporation) <Sintering conditions>
The unsintered bonded body was placed in a hot air oven, and the temperature was raised from 25° C. to 300° C. at a rate of 2° C./min. After reaching 300° C., it was maintained at 300° C. for 2 hours.
[Evaluation criteria (printability)]
◯: Printing was possible on the bonded portion 1.
×: Printing on the bonded portion 1 was not possible.

[Bonding strength (initial, after thermal cycle test)]
The bond strength (die shear strength) of the resulting bonded bodies was measured using the following measuring device and test conditions. Note that an asterisk (*) in Table 1 indicates that this evaluation was not performed because printing was not possible.

Measurement equipment: Universal bond tester (4000 series, manufactured by Daisy Japan Co., Ltd.)
<Test conditions>
Measurement height: 100 μm
Measurement speed: 500 μm/s
Specifically, the bonded body was fixed at the location of the bonded part 1, and the bond was pushed from the interface between the bonded part 1 and the bonding layer toward the bonded part 2 at a height of 100 μm at a speed of 500 μm/s, and the bond strength at which the bond was broken was determined. The bond strength (initial strength) immediately after the bonded body was produced and the bond strength after the following cycle test were measured and evaluated based on the following evaluation criteria. The larger the numerical value of the adhesive strength, the better, and a value of 15 MPa or more is within the practical range. The larger the numerical value of the evaluation criteria, the better, and an evaluation criteria value of 2 or less indicates poor.

[Evaluation criteria]
5: 30 MPa or more 4: 20 MPa or more but less than 30 MPa 3: 15 MPa or more but less than 20 MPa 2: 5 MPa or more but less than 15 MPa 1: Less than 5 MPa

<Cold-heat cycle test>
The bonded body was stored for 500 cycles, with one cycle consisting of holding it at -40°C for 30 minutes, then holding it at 25°C for 15 minutes, and then holding it at 150°C for 30 minutes. Thereafter, the bonded body was evaluated using the same procedures and criteria as in the above-mentioned bond strength evaluation method.

When the bonding paste of the comparative example was used, the bonding strength was significantly low, and when the broken sample after the die shear test was observed, the breakage was at the interface between the gold-plated SiC chip and the bonding layer. On the other hand, when the bonding paste of the example was used, the bonding strength was very high. When the bonding paste of the example was used, it was confirmed that the printability was excellent, even when it contained a high concentration of metal particles, and the bonding strength was very high, and the decrease in bonding strength was suppressed even after the thermal cycle test.

Claims (10)

A metal particle-containing composition comprising metal particles (A) having an average particle size of 180 nm to 1000 nm and a compound (B) having 20 to 80 carbon atoms and two or more functional groups (b) that are any one of a hydroxyl group, a carboxy group, and an amino group,
the compound (B) contains one or more selected from the group consisting of dimer acid, trimer acid, dimer diol, trimer triol, dimer diamine, and trimer triamine,
The metal particle-containing composition contains 0.1 to 3 parts by mass of the compound (B) relative to 100 parts by mass of the metal particles (A). The metal particle-containing composition according to claim 1, characterized in that the number of functional groups is 2 or 3. The metal particle-containing composition according to claim 1 or 2, characterized in that the compound (B) has a branched and/or cyclic structure. The metal particle-containing composition according to any one of claims 1 to 3, characterized in that the compound (B) has an n-valent hydrocarbon group, where n is the number of functional groups. The metal particle-containing composition according to claim 4, characterized in that the n-valent hydrocarbon group has 30 to 60 carbon atoms. 6. The metal particle-containing composition according to claim 1, wherein the compound (B) is contained in an amount of 0.3 to 2.5 parts by mass per 100 parts by mass of the metal particles (A). 7. The metal particle-containing composition according to claim 1, wherein the metal particles (A) have an average particle size of 200 nm to 400 nm. A bonding paste comprising a dispersion medium (C) and the metal particle-containing composition according to any one of claims 1 to 7 . The mass of the metal particles (A) relative to the sum of the masses of the metal particles (A), the compound (B), and the dispersion medium (C) is 80% by mass to 95% by mass. The bonding paste according to claim 8 . A bonded body in which a first portion to be bonded and a second portion to be bonded are bonded with the bonding paste according to claim 8 or 9 .