JP7581841B2 - 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 members together, between metal members and semiconductor elements, between metal members and light-emitting diode (LED) elements, etc. In recent years, in the field of next-generation power electronics technology, there has been a demand for devices such as SiC that can operate at high temperatures. As a bonding material for manufacturing such devices, there is a demand for alternative materials to solder from the viewpoint 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 that contains 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 with 6 to 8 carbon atoms. However, there is a problem in that the bonding strength at the bonded portion is poor, and the bonding strength decreases with thermal cycles.

Patent Document 2 discloses a bonding material that contains silver nanoparticles with an average primary particle size of 1 to 200 nm that are coated with an organic substance having 8 or less carbon atoms, and a flux component that has at least two carboxyl groups. In addition, Patent Document 3 discloses a bonding material that contains silver fine particles 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 fine particles.

However, even with these bonding materials, there was a problem that the strength of the bonded parts was poor, and the bonding strength decreased with thermal cycles, just like the technology disclosed in Patent Document 1. Furthermore, when a bonding paste containing a high concentration of silver nanoparticles was created to achieve a dense and strong bond, it had the disadvantage of significantly poor fluidity. As a result, there were problems with the printed parts being smudged and uncoated parts being formed in the process of printing the bonding paste on the parts to be bonded.

JP 2011-80147 A JP 2011-240406 A JP 2018-109232 A

The properties required for a bonding paste using metal particles include suitability for printing on the parts to be bonded, sufficient bonding strength, and minimal loss of bonding strength after reliability tests such as thermal cycles.

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

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), which are any one type selected from a hydroxyl group, a carboxy 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, in which 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, in which 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 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, in which the average particle size of the metal particles (A) is 200 nm to 400 nm.

The present invention also relates to a bonding 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) in 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 present invention also relates to a bonded body in which a first bonded part and a second bonded part are bonded with the 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 that does not decrease with thermal cycles. It also makes it possible to provide a bonding paste that has these effects as well as excellent printability. It also makes it possible to provide a bonded body that does not deteriorate with thermal cycles.

In this specification, "metal particles (A) having an average particle size of 180 nm to 1000 nm" may be abbreviated as "metal particles (A)," and "compound (B) having 20 to 80 carbon atoms and having multiple 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 the compound (B). The metal particle-containing composition may be formed by volatilizing a part 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, the core and the fine particles coated with a material different from the core material can be mentioned, specifically, for example, silver-coated copper powder, in which copper is used as the core and its surface is coated with silver.Furthermore, the powder can include metal oxide powders 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, since a bonded body having particularly excellent strength can be obtained. Furthermore, the metal particles (A) are more preferably silver, since they can be used at a wide range of firing temperatures and in various firing environments, such as under atmospheric pressure, in a nitrogen atmosphere, in a vacuum, or in a reducing atmosphere.

The metal particles (A) are within a specific average particle size range, and therefore have the ability to melt or bond together (hereinafter also referred to as sintering) in the temperature range of 200°C to 350°C at which the metal particle-containing composition or bonding paste is heated and sintered, making it possible for the particles to change into bulk metal. As a result, the objects to be joined are joined. Hereinafter, the area formed by sintering the metal particles (A) present between the objects to be joined is referred to as the bonding layer.

In the present invention, it is important to use metal particles (A) having a specific average particle size. In this specification, "average particle size" means 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 1000 nm, preferably 200 to 400 nm, and more preferably 200 to 300 nm.

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

The metal particles (A) may be used alone or in combination. If necessary, metal particles other than the metal particles (A) may be used in combination. When metal particles other than the metal particles (A) are used in combination, it is preferable to use a combination of metal particles having 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 included, as the dispersion medium evaporates from the bonding paste, it becomes difficult to form an interface with the bonded part, but by coexisting with the compound (B) of the present invention, even after a part or all of the dispersion medium (C) evaporates, the composition can behave as a liquid metal particle-containing composition, so that it is easy to form a good bonded interface that is integrated with the bonded part.

Compound (B) has two or more functional groups in the molecule selected from hydroxyl groups, carboxy groups, and amino groups (hereinafter, these functional groups will be referred to as "functional groups (b)") and has a structure with 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 including the carbon atom in the carboxy group is considered to be the number of carbon atoms in compound (B).

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 called an ester group or oxycarbonyl group), and a -C(=O)-NH- group (also called an amide group or iminocarbonyl group). It is preferable that compound (B) does not have any functional groups other than functional group (b).

The properties of compound (B) are not particularly limited, but it is preferably liquid at 200°C to 350°C, which is 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.

When 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 is possible to manufacture a bonded body with a strong bonding interface. Furthermore, even if voids are formed in the bonding layer during sintering, it is believed that the increased fluidity of the metal particle-containing composition will allow liquid compound (B) to flow into defective parts 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. When compound (B) has a branched and/or cyclic structure, it is preferable that compound (B) has a branched and/or cyclic structure, since it tends to be a liquid with low crystallinity and 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) is more preferably composed only of n-valent hydrocarbon groups, in that a strong bonded body can be obtained.

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, which is preferable because it makes it easier to obtain a denser bonding layer. As a result, the initial bonding strength is excellent, and it can be expected that the decrease in bonding strength due to thermal cycles will be further suppressed.

Specific examples of compound (B) having 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.

In addition, 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, for the reasons described above, it is more preferable that compound (B) be selected from dimer acid, trimer acid, dimer diol, trimer triol, dimer diamine, and trimer triamine.

Dimer acid, trimer acid, and tetramer acid can be produced by a polymerization reaction of unsaturated fatty acids. For example, they can be produced by a Diels-Alder reaction between oleic acid (carbon number 18) and linoleic acid (carbon number 18) or a radical reaction. The carbon numbers of dimer acid, trimer acid, and tetramer acid are preferably 36, 54, and 72, respectively. In addition, by appropriately changing the carbon number of the raw material unsaturated fatty acid, it is possible to produce a compound (B) having a carbon number other than the above. In this specification, the dimer, trimer, and tetramer 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 the dimer acid has been reduced to a hydroxyl group. Trimer triol, trimer triol, and tetramer tetraol each have a carboxy group of the tetramer acid each reduced to a hydroxyl group. Dimer diol, trimer triol, and tetramer tetraol preferably have carbon numbers of 36, 54, and 72, respectively.

Dimer diamine has a structure in which the carboxy group of dimer acid has been functionally converted to an amino group, trimer triamine has a structure in which the carboxy group of trimer acid has been functionally converted to an amino group, and tetramer tetramine has a structure in which the carboxy group of tetramer acid has been functionally converted to an amino group. Dimer diamine, trimer triamine, and tetramer tetramine preferably have carbon numbers of 36, 54, and 72, 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 polymerization products, or a specific single compound may be used.

In the metal particle-containing composition of the present invention, the 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 the metal particles (A). Within this range, it is possible to obtain a bonded body that is particularly excellent in initial bond strength and in which the decrease in bond strength due to thermal cycles is suppressed.

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 include, but are not limited to, terpineol, dihydroterpineol, dihydroterpinyl acetate, Tersorb MTPH (manufactured by Nippon Terpene Co., Ltd.), Texanol (2,2,4-trimethylpentane-1,3-diol monoisobutyrate), carbitol, carbitol acetate, butyl carbitol, isophorone, γ-butyrolactone, 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, and isoparaffin-based solvents contained in hydrocarbon-based solvents.

Of these dispersion media (C), terpineol, dihydroterpineol, tersolve MTPH, texanol, carbitol, carbitol acetate, butyl carbitol, isophorone, γ-butyrolactone, 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, if the boiling point of the dispersion medium (C) is lower than the boiling point of the compound (B), the amount of the dispersion medium (C) coexisting with the metal particle-containing composition during sintering can be reduced, and the content of the metal particles (A) can be increased, which is preferable.

The bonding paste of the present invention uses a combination of metal particles (A) and compound (B) to have excellent fluidity even when it contains a high concentration of metal particles (A), i.e., when the content ratio of dispersion medium (C) is low, and therefore has excellent printability on the bonded parts. As a result, it is possible to obtain a stronger bonded body with fewer defects.

In the bonding paste, the mass ratio of the metal particles (A) to the sum of the masses of the metal particles (A), the compound (B), and the dispersion medium (C) is preferably 80% by mass to 95% by mass, and more preferably 85% by mass to 94% by mass. By including the above range, it is possible to ensure good printability as a bonding paste, suppress the residue of the dispersion medium (C) in the bonded body, suppress the occurrence of voids originating from the dispersion medium (C), and achieve good bonding strength.

The joining paste of the present invention may contain additives, such as a sintering accelerator, binder resin, or resin-type dispersant.

Examples of devices for preparing a 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, a self-rotating mixer, etc.

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

The method of applying the bonding paste to the objects to be bonded is not particularly limited as long as it can be applied uniformly to the members. Examples include various printing methods such as screen printing, flexographic printing, offset printing, gravure printing, metal mask printing, and gravure offset printing, and ejection 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 be joined coated with the joining paste of the present invention, pressure can be applied during the placement. The pressure is set appropriately depending on the viscosity of the joining paste and the drying state of the paste, but is preferably 0.1 to 40 MPa, and more preferably 0.3 to 30 MPa.

The sintering conditions for joining a laminate in which a second bonded portion is placed on a first bonded portion may be changed as appropriate, but may include, for example, conditions such as atmospheric pressure, a nitrogen atmosphere, a vacuum, or a reducing atmosphere at 200 to 350°C. As the sintering device, a hot air oven, an infrared oven, a reflow oven, a microwave oven, a hot plate, an optical sintering device, etc. 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, more preferably 0.3 to 30 MPa.

Before the firing process, a preliminary drying process can be carried out as appropriate to remove organic components from the bonded coating film. For example, a pre-drying process can be carried out using a device similar to the firing device under conditions ranging from 60 to 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 it, and heat it up to about 300°C at a heating rate of about 2°C/min to perform sintering. After the heating is complete, it is preferable to maintain the temperature higher than the temperature at the end of the heating for about 10 minutes to 2 hours.

The type of the parts to be joined is not particularly limited, and examples include metal materials, semiconductor materials, plastic materials, ceramic materials, etc. Also included are electronic elements.

Examples of the metal 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 the ceramic material include glass and silicon.

Examples of electronic elements include semiconductor elements, LED elements, and power device elements.

The first and second joined parts may be of different types, not just the same type. The surfaces of the joined parts may be corona-treated, plated, or otherwise treated to increase the joining strength at the joined location.

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 described in detail below using examples and comparative examples, but the technical scope of the present invention is not limited thereto. In the examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass", and the numerical values in the 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 obtain a 0.5 M solution, and then 1.6 parts of diethylaminoethanol and 0.28 parts of oleic acid were added as a dispersant. After that, 73.1 parts of a 20% aqueous solution of succinic dihydrazide (hereinafter, SUDH) was added dropwise as a reducing agent, and the color of the solution changed from light yellow to dark brown. The temperature was raised to 40° C. to allow the reaction to proceed. After leaving the mixture to stand and separating, the aqueous phase was removed to remove excess reducing agent and impurities. Distilled water was further added to the toluene layer several times to wash it, After repeating the separation, the process of adding toluene, centrifuging, and then 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 size of the metal particles A1 was determined by the method described below, and d50 was 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. Among the metal particles, 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, 1000 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 liquid, and 115 g of trimer acid trimethyl ester was obtained by distillation under reduced pressure.
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, while stirring the dispersion, a solution obtained by diluting 50 g of trimer acid trimethyl ester with 70 ml of diethyl ether was dropped over 120 minutes, and the temperature was kept below about 30° C. to cause a reaction. After dropping, the mixture was stirred for about 40 minutes, and then 13 g of ion-exchanged water was carefully dropped 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 a 10% aqueous sulfuric acid solution was added. After standing 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 it became neutral, and the diethyl ether was distilled off to obtain 31 g of a trimer triol having 54 carbon atoms and consisting of three hydroxyl groups and a trivalent hydrocarbon group having a branched and cyclic structure. The obtained trimer triol was a viscous liquid at 25° C.

[Measurement of particle size]
Isopropyl alcohol was added to each metal particle (A) and dispersed in an ultrasonic disperser to obtain a 0.5% by mass dispersion. The particle size of the metal particle (A) in the obtained dispersion was measured using Nanotrac UPA-EX150 (manufactured by Nikkiso Co., Ltd.) to determine the average particle size (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 compounds 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. It consists 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. It consists 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. It consists of two hydroxyl groups and a divalent hydrocarbon group having a branched and cyclic structure. Liquid)
Compound B5: Priamine 1071 [a mixture of a dimer triamine having 36 carbon atoms (liquid, consisting of two amino groups and a divalent hydrocarbon group having a branched and cyclic structure) and a trimer triamine having 54 carbon atoms (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. It consists 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 state)
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 stirrer 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 types and amounts 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 indicate parts, and blank spaces indicate that no compounding was performed.

[Preparation of Joint]
Each joining paste was printed once on the plated surface of the joining part 1 described below under the printing conditions described below, and then the plated surface of the joining part 2 (chip) described below was placed facing the joining paste surface and heated under the sintering conditions described below to obtain each joining body.
<Jointed part 1>
Gold-plated copper substrate: 20 x 20 x 3 mm
<Jointed part 2>
・Gold-plated SiC chip: 5 x 5 x 0.3 mm
<Printing conditions (metal mask printing)>
Metal mask: opening 4 mm square, plate thickness 50 μm (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., the bonded body was held 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 obtained bonded body 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 site 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 to determine the bond strength at which the bond was broken. The bond strength (initial strength) immediately after the bonded body was produced and the bond strength after the cycle test described below were measured and evaluated based on the following evaluation criteria. The larger the adhesive strength value, the better, and 15 MPa or more is within the practical range. The larger the evaluation criterion value, the better, and an evaluation criterion 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 being a process of holding the bonded body at −40° C. for 30 minutes, then holding the bonded body at 25° C. for 15 minutes, and then holding the bonded body at 150° C. for 30 minutes. Thereafter, the bonded body was evaluated according to the same procedure and criteria as 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 was observed after the die shear test, it was found to have broken 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. It was confirmed that when the bonding paste of the example was used, even when it contained a high concentration of metal particles, it had excellent printability, very high bonding strength, and the decrease in bonding strength was suppressed even after the thermal cycle test was performed.

Claims (12)

A metal particle-containing composition comprising metal particles (A) having an average particle size of 180 nm to 400 nm and a compound (B) having 20 to 80 carbon atoms and two or more functional groups (b) that are any one of hydroxyl groups, carboxy groups, and amino groups. 2. The metal particle-containing composition according to claim 1, wherein the number of the functional groups (b) 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. 4. The metal particle-containing composition according to claim 1, wherein the compound (B) has a hydrocarbon group having a valence of n, where n is the number of the functional groups (b) . The metal particle-containing composition according to claim 4, characterized in that the carbon number of the n-valent hydrocarbon group is 30 to 60. The metal particle-containing composition according to any one of claims 1 to 5, characterized in that 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 according to any one of claims 1 to 6, characterized in that it contains 0.1 to 3 parts by mass of the compound (B) per 100 parts by mass of the metal particles (A). The metal particle-containing composition according to any one of claims 1 to 7, characterized in that it contains 0.3 to 2.5 parts by mass of the compound (B) per 100 parts by mass of the metal particles (A). The metal particle-containing composition according to any one of claims 1 to 8, wherein the average particle size of the metal particles (A) is 200 nm to 400 nm. A bonding paste containing a dispersion medium (C) and a metal particle-containing composition according to any one of claims 1 to 9. The joining paste according to claim 10, wherein the mass of the metal particles (A) in 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. A method for manufacturing a joined body, comprising the steps of applying the joining paste according to claim 10 or 11 to a first joined part, placing a second joined part thereon, and joining the first joined part and the second joined part by sintering.