JPWO2019026799A1 - Metal bonding composition - Google Patents

Abstract

The present invention relates to a metal bonding composition suitable for forming a metal bonding material excellent in durability against a thermal load applied in a heat cycle test or the like, and bonding of metal surfaces by firing the metal bonding composition. Provided are a metal bonded laminate and an electric control device. The metal bonding composition of the present invention is a metal bonding composition used for baking and bonding metal surfaces, the metal bonding composition containing silver particles and a dispersion medium, and the silver bonding composition. The particles include nanoparticles having a particle size of 1 to 99 nm, submicron particles having a particle size of 100 to 999 nm, and / or micron particles having a particle size of 1 to 999 μm, and the tensile strength of the coating when fired at 275 ° C. The breaking stress is 100 MPa or more.

Description

The present invention relates to a metal bonding composition, a metal bonded laminate, and an electric control device.

Conventionally, bonding materials such as solder, conductive adhesive, silver paste, and anisotropic conductive film are used for mechanical, electrical and / or thermal bonding between metal parts. These joining materials may be used for joining not only metal parts but also ceramic parts and resin parts. Applications of the bonding material include, for example, an application for bonding a light emitting element such as an LED to a substrate, an application for bonding a semiconductor chip to the substrate, an application for further bonding these substrates to a heat dissipation member, and the like. For example, Patent Documents 1 to 3 are cited as prior art documents relating to the bonding material.

Patent Document 1 discloses a bonding composition containing inorganic particles and an organic component, and the inorganic particles irreversibly exceed the linear expansion coefficient of the inorganic substance constituting the inorganic particles as the temperature rises. A bonding composition is disclosed that is characterized by swelling.

In Patent Document 2, the main silver particles are coated with a carboxylic acid having 6 or less carbon atoms, the nano silver particles having an average primary particle diameter of 10 to 30 nm, and the secondary silver particles are coated with a carboxylic acid having 6 or less carbon atoms. Nano silver particles having an average primary particle diameter of 100 to 200 nm, silver particles composed of submicron silver particles having an average primary particle of 0.3 to 3.0 μm, a low boiling point solvent having a boiling point of 100 to 217 ° C., TEM image taken at a magnification of 300,000 times, which is a bonding material comprising two types of polar solvents having different high boiling point solvents at 230 to 320 ° C. and a dispersant having a phosphate ester group. Is an average of the particle diameters measured for 200 or more particles by image software for performing circular particle analysis to identify individual particles, and the content of the silver particles is 95% of the total amount of bonding material. The amount of the main silver particles is 10 to 40% by mass with respect to the total amount of bonding material, and the content ratio of the solvent having the lower boiling point and the solvent having the higher boiling point is the content of the two kinds of solvents. In addition, a bonding material having a mass ratio of 3: 5 to 1: 1 is disclosed.

In Patent Document 3, metal submicron particles having an average primary particle diameter (D50 diameter) of 0.5 to 3.0 μm and an average primary particle diameter of 1 to 200 nm, which are measured with a Microtrac particle size distribution analyzer, are disclosed. Thus, a bonding material including metal nanoparticles coated with a fatty acid having 6 carbon atoms and a dispersion medium for dispersing them is disclosed.

International Publication No. 2017/006531 Japanese Patent No. 5976684 Japanese Patent No. 5824201

The present inventor has been conducting research and development on a metal bonding composition containing metal particles in order to produce a metal bonding material having high bonding strength, but the metal bonding is performed by a thermal load applied in a heat cycle test or the like. Cracks may occur in the material, and there is room for improvement in durability.

The present invention has been made in view of the above situation, and is a metal bonding composition suitable for forming a metal bonding material excellent in durability against a thermal load applied in a heat cycle test or the like, and for the metal bonding described above. An object of the present invention is to provide a metal bonded laminate and an electric control device in which the metal surfaces are bonded by firing the composition.

The present inventor conducted various studies on a metal bonding composition suitable for forming a metal bonding material having excellent durability against a thermal load applied in a heat cycle test or the like. As described above, the combined use of nanoparticles having a particle size of 1 to 99 nm and submicron particles having a particle size of 100 to 999 nm and / or micron particles having a particle size of 1 to 999 μm can improve the tensile rupture stress of the film after firing. I found. A heat cycle test is performed by adjusting the particle size of the silver particles, the type of the dispersion medium, and the like to be blended in the metal bonding composition so that the tensile breaking stress of the coating when baked at 275 ° C. is 100 MPa or more. As a result, it was found that the increase in the void ratio (voidage ratio) due to the thermal load applied by the process can be suppressed, and a metal bonding material having excellent durability can be formed, and the present invention has been completed.

The metal bonding composition of the present invention is a metal bonding composition used for baking and bonding metal surfaces, the metal bonding composition containing silver particles and a dispersion medium, and the silver bonding composition. The particles include nanoparticles having a particle size of 1 to 99 nm, submicron particles having a particle size of 100 to 999 nm, and / or micron particles having a particle size of 1 to 999 μm, and the tension of the coating when fired at 275 ° C. The breaking stress is 100 MPa or more.

The silver particles preferably include the nanoparticles and the submicron particles, and more preferably the mass ratio of the nanoparticles and the submicron particles is 4: 6 to 7: 3.

The metal bonding laminate of the present invention is a metal bonding laminate including a metal bonding material for bonding the first metal surface and the second metal surface, and the metal bonding material is a composition for metal bonding of the present invention. It is a sintered body of a product.

At least one of the first metal surface and the second metal surface is preferably the surface of a base material or a plating layer made of Cu, Ag, or Au.

The first metal surface is preferably a part of the semiconductor chip, and the second metal surface is preferably a part of the substrate.

The electric control device of the present invention includes the metal bonded laminate of the present invention.

According to the present invention, a metal bonding composition suitable for forming a metal bonding material excellent in durability against a thermal load applied in a heat cycle test or the like, and a metal surface by firing the metal bonding composition It is possible to provide a metal-bonded laminate and an electric control device in which bonding is performed.

It is a flowchart explaining the preparation methods of the test piece for the measurement of the tensile fracture stress of the composition for metal joining. It is the plane schematic diagram which showed the shape and dimension (unit: mm) of the test piece for the measurement of the tensile fracture stress of the composition for metal joining. It is the cross-sectional schematic diagram which showed the structure of the power device which is an example of a metal joining laminated body.

The metal bonding composition of the present embodiment is a metal bonding composition used for baking and bonding metal surfaces, and the metal bonding composition contains silver particles and a dispersion medium, and The silver particles include nanoparticles having a particle size of 1 to 99 nm, submicron particles having a particle size of 100 to 999 nm, and / or micron particles having a particle size of 1 to 999 μm. The tensile rupture stress is 100 MPa or more.

The metal bonding composition has a tensile breaking stress of 100 MPa or more when fired at 275 ° C. The coating may be fired under no pressure condition. Moreover, it is preferable that the baking time of a film is 60 minutes or more. When the tensile breaking stress is less than 100 MPa, a high thermal stress is generated in a heat cycle test in which the upper limit temperature is set to a high temperature such as 175 ° C. or 200 ° C., so that cracks are vigorously generated in the metal bonding material. The upper limit of the tensile breaking stress is not particularly limited, and may be, for example, 500 MPa.

A specific example of a method for measuring the tensile breaking stress of the coating will be described below with reference to FIGS. FIG. 1 is a flow diagram for explaining a method for producing a test piece for measuring a tensile breaking stress of a metal bonding composition. FIG. 2 is a schematic plan view showing the shape and dimensions (unit: mm) of the test piece for measuring the tensile breaking stress of the metal bonding composition.

(Measurement method of tensile breaking stress)
(1) As shown in FIG. 1A, a metal bonding composition 52 is slid using a dumbbell-shaped No. 7 type (see FIG. 2) metal mask (thickness 90 μm) defined in JIS K 6251. Printing on the glass 51.
(2) As preliminary drying, the printed metal bonding composition 52 is placed in an oven set at 70 ° C. and dried for 30 minutes.
(3) As shown in FIG. 1B, a slide glass 53 is placed on the dried metal bonding composition 52 (a portion surrounded by a dotted line in FIG. 2), and a reflow furnace (Shin Apex Co., Ltd.). Baked in the product). The firing process in the reflow furnace is performed in an air atmosphere, and the temperature is increased from room temperature to a maximum temperature of 275 ° C. at a temperature increase rate of 3.8 ° C./min, and then held at 275 ° C. for 60 minutes. During the firing treatment, no pressure is applied and no pressure is applied. Note that the non-pressurization means bonding without applying a load other than the weight of the object to be bonded such as a semiconductor chip. In this measurement method, an actual bonded state (covered object) is obtained by placing the slide glass 53. The state where the joined body is placed) is reproduced.
(4) As shown in FIG. 1C, after the fired metal bonding composition 52 is taken out from the reflow furnace, it is peeled off from the slide glasses 51 and 53 to obtain a test piece 54 for a tensile test.
(5) The tensile test is performed with a universal tensile tester 5969 manufactured by Instron Corporation at a measurement speed of 0.72 mm / min. The tensile breaking stress when the test piece 54 is broken is measured.

The tensile rupture stress is measured on a film fired at 275 ° C. At the time of firing the metal bonding composition, the dispersion medium (solvent) is first volatilized or decomposed to volatilize, and then organic components other than the dispersion medium such as a dispersant used for dispersing the silver particles are volatilized or decomposed. Although it volatilizes, the silver particles are excellent in low-temperature sinterability, so if fired to 275 ° C., the silver is removed by organic component removal from the metal bonding composition and the particles are necked (partial fusion). The sintering of the particles can be promptly advanced. The metal bonding composition of the present embodiment is preferably used after being baked at 275 ° C.

The metal bonding composition of the present embodiment preferably has a mass reduction rate after firing of 6 to 20%, more preferably 8 to 15%, and still more preferably 11 to 12%. The mass reduction rate can be calculated from the result of differential thermal analysis (TG-DTA). According to TG-DTA, the presence or absence of a reaction (mainly combustion / oxidative decomposition) and the end point of the reaction can be confirmed.

According to the Hall-Petch equation of the following equation (A), it is considered that the tensile fracture stress can be improved as the crystal grain size is reduced.
σy = σ ₀ + k / √d (A)
σy: Yield stress, σ ₀ : Friction stress, k: Resistance coefficient against slip of crystal grain boundary, d: Average crystal grain size

Here, as a method of reducing the crystal grain size, a method of including nanoparticles in the silver particles to be blended in the metal bonding composition, a method of increasing the ratio, or a method of reducing the time during which the silver particles are sintered Is mentioned. When the ratio of the nanoparticles in the silver particles blended in the metal bonding composition is increased, the necking portion between the silver particles can be increased. If the time during which the silver particles are sintered is shortened, the progress of fusion between the silver particles can be suppressed. Shortening the time during which silver particles are sintered can also be achieved by delaying the removal of the organic components incorporated in the metal bonding composition.

As described above, as a method of adjusting the tensile rupture stress of the coating when fired at 275 ° C., a method of increasing the ratio of nanoparticles in the silver particles to be blended in the metal bonding composition, a dispersant or a dispersion medium The method of changing the type of is preferable. With respect to the dispersing agent, those which volatilize below 275 ° C. (= the particles are sintered) are preferable. Regarding the dispersion medium, those that volatilize before the silver particles are sintered are preferred. Moreover, it is preferable to reduce the amount of solvent remaining before the firing step.

The metal bonding composition is not particularly limited as long as it contains silver particles and a dispersion medium, but is preferably pasty so as to be easily applied. Further, in order to make migration less likely to occur, in addition to silver particles, a metal whose ionization column is nobler than hydrogen, that is, particles of gold, copper, platinum, palladium, or the like may be used in combination.

The silver particles include nanoparticles having a particle size of 1 to 99 nm (also referred to as nano silver particles), submicron particles having a particle size of 100 to 999 nm, and / or micron particles having a particle size of 1 to 999 μm (also referred to as micron silver particles). Is included. The nanoparticles may be dispersed in the metal bonding composition separately from the submicron particles or micron particles, or may be attached to at least a part of the surface of the submicron particles or micron particles. The nanoparticles, submicron particles, and micron particles preferably have independent particle size distribution peaks.

The average particle diameter of the silver particles can be measured by a dynamic light scattering method, a small angle X-ray scattering method, and a wide angle X-ray diffraction method, and is suitable for measuring the particle size of micron particles. is there. In the present specification, “average particle diameter” refers to a dispersed median diameter. Other methods for measuring the average particle size include a method of calculating an arithmetic average value of particle sizes of about 50 to 100 particles from a photograph taken using a scanning electron microscope or a transmission electron microscope. Suitable for measuring the particle size of nanoparticles.

The average particle diameter of the nanoparticles is not particularly limited as long as the effects of the present invention are not impaired. If nanoparticles having an average particle diameter of 1 nm or more are used as small-diameter silver particles, a metal bonding composition capable of forming a good metal bonding material can be obtained, and the production of silver particles is practical without increasing the cost. is there. Moreover, if it is 99 nm or less, the dispersibility of a nanoparticle cannot change easily with time, and it is preferable.

The silver particles preferably include nanoparticles and submicron particles, and the mass ratio of the nanoparticles and submicron particles contained in the silver particles is more preferably 4: 6 to 7: 3. If the mass ratio of nanoparticles and submicron particles is less than 4: 6 (the mass ratio of nanoparticles is less than 40%), the particles are difficult to connect with each other, and the bond strength between the particles (equivalent to tensile strength) decreases. In the heat cycle test, cracks may occur at an early stage. When the mass ratio of the nanoparticles and the submicron particles exceeds 7: 3 (the mass ratio of the nanoparticles exceeds 70%), the shrinkage at the time of firing increases, so that the sintered body of the composition for metal bonding The percentage of voids (voids) may be too high.

The silver particles preferably contain nanoparticles and micron particles, and the mass ratio of the nanoparticles and micron particles contained in the silver particles is more preferably 7: 3 to 8: 2. If the mass ratio of the nanoparticles and micron particles is less than 7: 3 (the mass ratio of the nanoparticles is less than 70%), the tensile strength is lowered, so that cracks may occur early in the heat cycle test. If the mass ratio of nanoparticles to micron particles exceeds 8: 2 (the mass ratio of nanoparticles exceeds 80%), the proportion of voids (voids) in the sintered body of the metal bonding composition may become too high. There is.

The average particle diameter of the micron particles is not particularly limited as long as the effects of the present invention are not impaired, but is preferably 1 to 20 μm. By using micron particles having an average particle diameter of 1 to 20 μm, volume shrinkage due to sintering can be reduced, and a homogeneous and dense bonding material can be obtained. When sub-micron particles having an average particle size of less than 1 μm are used as large-diameter silver particles, sintering proceeds at a low temperature, but as the average particle size increases, volume shrinkage increases as the particles are sintered together. There is a possibility that the joined body cannot follow the volume shrinkage. In such a case, defects such as voids occur in the metal bonding material, and the bonding strength and reliability of the metal bonding material are reduced. On the other hand, when particles having an average particle size larger than 20 μm are used, sintering at a low temperature hardly proceeds and large voids formed between silver particles may remain after sintering. The average particle diameter of the micron particles is more preferably 1 to 10 μm.

The silver particles can be obtained, for example, by mixing a metal ion source and a dispersant and using a reduction method.

The dispersion medium is not particularly limited as long as it can disperse the silver particles, and examples thereof include organic solvents such as hydrocarbons, alcohols, and carbitols. The dispersion medium is preferably one that does not volatilize during the step of applying the metal bonding composition, and one that is difficult to volatilize at room temperature is preferred.

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

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

Examples of the cyclic hydrocarbon include toluene and xylene.

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), ferrandylene, mentadiene, teleben, dihydro. Cymen, moslen, isoterpinene, isoterpinene (also referred to as isoterpinene), clitomen, kautssin, cajeptene, oilimene, pinene, turpentine, menthane, pinane, terpene, cyclohexane and the like can be mentioned.

The alcohol is a compound containing one or more OH groups in the molecular structure, and examples thereof include aliphatic alcohols, cyclic alcohols, and alicyclic alcohols, and each may be used alone or in combination of two or more. Good. Moreover, a part of OH group may be induced | guided | derived to the acetoxy group etc. in the range which does not impair the effect of this invention.

Examples of the aliphatic alcohol include heptanol, octanol (1-octanol, 2-octanol, 3-octanol, etc.), decanol (1-decanol, etc.), lauryl alcohol, tetradecyl alcohol, cetyl alcohol, 2-ethyl-1 -Saturated or unsaturated C6-30 aliphatic alcohols, such as hexanol, octadecyl alcohol, hexadecenol, oleyl alcohol, etc. are mentioned.

Examples of the cyclic alcohol include cresol and eugenol.

Examples of the alicyclic alcohol include cycloalkanols such as cyclohexanol, terpineols (including α, β, γ isomers, or any mixture thereof), and terpene alcohols such as dihydroterpineol (monoterpene alcohols, etc.). , Dihydroterpineol, myrtenol, sobrerol, menthol, carveol, perillyl alcohol, pinocarveol, sobrerol, berbenol and the like.

Examples of the carbitols include butyl carbitol, butyl carbitol acetate, hexyl carbitol and the like.

The initial content when the dispersion medium is contained in the metal bonding composition may be adjusted according to desired properties such as viscosity, and the initial content of the dispersion medium in the metal bonding composition is 1 to 30. It is preferable that it is mass%. When the initial content of the dispersion medium is 1 to 30% by mass, the effect of adjusting the viscosity can be obtained within a range that is easy to use as a metal bonding composition. A more preferable initial content of the dispersion medium is 1 to 20% by mass, and a more preferable initial content is 1 to 15% by mass.

As a dispersion medium to be blended in the metal bonding composition, hexyl carbitol and butyl carbitol acetate are suitable. It is preferable that 50% by mass or more of hexyl carbitol is contained in the dispersion medium. Moreover, the preferable solid content density | concentration of the said composition for metal joining is 88-93 mass%. If these conditions are satisfied, the viscosity can be adjusted to an appropriate range without reducing the bonding strength and void ratio, and thus a metal bonding composition having excellent printability with a metal mask can be obtained. Moreover, since the stability over time of the viscosity can be ensured, the pot life of the metal bonding composition can be lengthened.

The metal bonding composition may contain an organic component other than the dispersion medium. The organic component is not particularly limited, and additives used for the purpose of adjusting the dispersibility of silver particles, the viscosity, adhesion, drying property, surface tension, coating property (printability) of the metal bonding composition, and the like. Is used.

Examples of the additive that improves the dispersibility of the silver particles include amines, carboxylic acids, polymer dispersants, unsaturated hydrocarbons, and the like. Amine and carboxylic acid are adsorbed to the surface of the silver particles with an appropriate strength and prevent the silver particles from contacting each other, which contributes to the stability of the silver particles in the storage state. It is considered that the additive adsorbed on the surface of the silver particles moves and / or volatilizes from the surface of the silver particles during heating, thereby promoting the fusion between the silver particles and the bonding with the base material. The polymer dispersant can maintain dispersion stability without losing the low-temperature sinterability of the silver particles by adhering an appropriate amount to at least a part of the silver particles.

An organic component adheres to at least a part of the surface of the silver particle (that is, at least a part of the surface of the silver particle is covered with an organic protective layer composed of the organic component), and the organic component (organic protection The layer) preferably contains an amine. In order to stably store nanometer-sized particles exhibiting melting point lowering ability, it is desirable to provide an organic protective layer on at least a part of the surface of the metal particles. Here, the amine can be suitably used as an organic protective layer because the functional group is adsorbed to the surface of the silver particles with an appropriate strength.

The amine is not particularly limited, and examples thereof include alkylamines (linear alkylamines, which may have a side chain) such as oleylamine, butylamine, pentylamine, hexylamine, hexylamine, octylamine; N- (3-methoxypropyl) propane-1,3-diamine, 2-methoxyethylamine, 3-methoxypropylamine, 3-ethoxypropylamine and other alkoxyamines; cyclopentylamine, cyclohexylamine and other cycloalkylamines; aniline and other allylamines Primary amines such as dipropylamine, dibutylamine, piperidine, hexamethyleneimine, etc., and tertiary amines such as tripropylamine, dimethylpropanediamine, cyclohexyldimethylamine, pyridine, quinoline, etc. It is possible to have.

The amine is preferably an amine having about 2 to 20 carbon atoms, more preferably an amine having 4 to 12 carbon atoms, and still more preferably an amine having 4 to 7 carbon atoms. Specific examples of the amine having 4 to 7 carbon atoms include heptylamine, butylamine, pentylamine, and hexylamine. Since amines having 4 to 7 carbon atoms move and / or volatilize at a relatively low temperature, the low-temperature sinterability of silver particles can be fully utilized. The amine may be linear, branched, or have a side chain.

In addition, when these organic components are chemically or physically bonded to the silver particles, it is also considered that they are changed to anions and cations. In this embodiment, ions derived from these organic components are used. And organic complexes are also included in the organic components.

The amine may be 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, or a mercapto group. Moreover, the said amine may be used independently, respectively and may use 2 or more types together. In addition, the boiling point at normal temperature is preferably 300 ° C. or lower, and more preferably 250 ° C. or lower.

As the carboxylic acid, compounds having at least one carboxyl group can be widely used, and examples thereof include formic acid, oxalic acid, acetic acid, hexanoic acid, acrylic acid, octylic acid, levulinic acid, and oleic acid. A part of carboxyl groups of the carboxylic acid may form a salt with a metal ion. In addition, about the said metal ion, 2 or more types of metal ions may be contained.

The carboxylic acid may be a compound containing a functional group other than a carboxyl group, such as an amino group, a hydroxyl group, an alkoxy group, a carbonyl group, an ester group, or a mercapto group. In this case, the number of carboxyl groups is preferably equal to or greater than the number of functional groups other than carboxyl groups. Moreover, the said carboxylic acid may be used independently, respectively and may use 2 or more types together. In addition, the boiling point at normal temperature is preferably 300 ° C. or lower, and more preferably 250 ° C. or lower.

Also, the amine and carboxylic acid form an amide group. Since the amide group is also adsorbed moderately on the surface of the silver particle, the organic component may contain an amide group.

The composition ratio (mass) in the case of using an amine and a carboxylic acid in combination can be arbitrarily selected within the range of 1/99 to 99/1, but is preferably 20/80 to 98/2. Preferably it is 30 / 70-97 / 3.

A commercially available polymer dispersant can be used as the polymer dispersant. Examples of commercially available polymer dispersants include Solsperse 11200, Solsperse 13940, Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 20000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000, Solsperse 54000 (and above, Japan) Dispersic (DISPERBYK) 142; Dispersic 160, Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 166, Dispersic 170, Dispersic 180, Dispersic 182, Dispersic 184, Dispers Big 190, Dispersic 2155 ( Top, manufactured by Big Chemie Japan); EFKA-46, EFKA-47, EFKA-48, EFKA-49 (above, manufactured by EFKA Chemical); polymer 100, polymer 120, polymer 150, polymer 400, polymer 401, polymer 402 , Polymer 403, polymer 450, polymer 451, polymer 452, polymer 453 (manufactured by EFKA Chemical Co., Ltd.); Ajisper PB711, Ajisper PA111, Ajisper PB811, Ajisper PW911 (manufactured by Ajinomoto Co., Inc.); -22, Floren DOPA-17, Floren TG-730W, Floren G-700, Floren TG-720W (manufactured by Kyoeisha Chemical Co., Ltd.) and the like. From the viewpoints of low-temperature sinterability and dispersion stability, it is preferable to use Solsperse 11200, Solsperse 13940, Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 28000, Solsperse 54000, Dispersic 142 or Dispersic 2155.

The content of the polymer dispersant is preferably 0.03 to 15% by mass. If the content of the polymer dispersant is 0.1% by mass or more, the dispersion stability of the obtained metal bonding composition is improved, but if the content is too large, the bonding property is lowered. From such a viewpoint, the more preferable content of the polymer dispersant is 0.05 to 3% by mass, and the more preferable content is 0.1 to 2% by mass.

Examples of the unsaturated hydrocarbon include ethylene, acetylene, benzene, acetone, 1-hexene, 1-octene, 4-vinylcyclohexene, cyclohexanone, terpene alcohol, allyl alcohol, oleyl alcohol, 2-palmitoleic acid, and petroceric acid. Oleic acid, elaidic acid, thianic acid, ricinoleic acid, linoleic acid, linoleic acid, linolenic acid, arachidonic acid, acrylic acid, methacrylic acid, gallic acid, salicylic acid and the like.

Among the unsaturated hydrocarbons, unsaturated hydrocarbons having a hydroxyl group are preferably used. The hydroxyl group is easily coordinated to the surface of the silver particle, and can suppress aggregation of the silver particle. Examples of the unsaturated hydrocarbon having a hydroxyl group include terpene alcohol, allyl alcohol, oleyl alcohol, thianic acid, ricinoleic acid, gallic acid, salicylic acid, and the like. Preferably, it is an unsaturated fatty acid having a hydroxyl group, and examples thereof include thianic acid, ricinoleic acid, gallic acid, salicylic acid and the like.

As a dispersing agent mix | blended with the said composition for metal joining, the amine or carboxylic acid whose boiling point is 150-300 degreeC is preferable, and levulinic acid is used especially suitably especially.

In addition, the above-mentioned organic component includes an oligomer component, a resin component, an organic solvent (a part of the solid content may be dissolved or dispersed), an interface, and the like, as long as the effects of the present invention are not impaired. Activators, thickeners, surface tension modifiers and the like may be included.

Examples of the resin component include polyester resins, polyurethane resins such as blocked isocyanate, polyacrylate resins, polyacrylamide resins, polyether resins, melamine resins, terpene resins, and the like. These may be used alone or in combination of two or more.

As said organic solvent, except what was mentioned as said dispersion medium, 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, weight average molecular weight in the range 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, 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, hectorite, polyester emulsion resin, acrylic emulsion resin, polyurethane emulsion resin, emulsion such as blocked isocyanate, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, Examples thereof include cellulose derivatives such as hydroxypropylcellulose and hydroxypropylmethylcellulose, polysaccharides such as xanthan gum and guar gum, and these may be used alone or in combination of two or more.

The surfactant is not particularly limited, and any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. Examples thereof include alkylbenzene sulfonate and quaternary ammonium salt. It is done. Since the effect can be obtained with a small addition amount, a fluorosurfactant is preferable.

It is preferable that content of the organic component in the composition for metal joining of this embodiment is 5-50 mass%. If the content is 5% by mass or more, the storage stability of the metal bonding composition tends to be improved, and if it is 50% by mass or less, the conductivity of the metal bonding composition tends to be good. The more preferable content of the organic component is 5 to 30% by mass, and the more preferable content is 5 to 15% by mass.

The metal bonding composition of the present embodiment is used for baking and bonding metal surfaces. A metal bonded laminate including a metal bonding material for bonding the first metal surface and the second metal surface, wherein the metal bonding material is a sintered body of the metal bonding composition of the present invention. A laminate is also an embodiment of the present invention. That is, in the metal bonded laminate of the present embodiment, the first bonded body having the first metal surface and the second bonded body having the second metal surface baked the composition for metal bonding. It is joined by a metal joining material comprising a silver particle sintered layer obtained by bonding.

The type of the first bonded body and the second bonded body is not particularly limited, but is preferably a member having heat resistance to such an extent that it is not damaged by the temperature during the heat sintering of the metal bonding composition. It may be rigid or flexible. Moreover, the shape and thickness of a 1st to-be-joined body and a 2nd to-be-joined body are not specifically limited, It can select suitably.

Although the kind of metal joining laminated body is not specifically limited, For example, the power semiconductor element (power device) is suitable. The first metal surface is preferably a part of the semiconductor chip, and the second metal surface is preferably a part of the substrate. Moreover, from the viewpoint of obtaining high bonding strength, at least one of the first metal surface and the second metal surface is preferably the surface of a base material or a plating layer made of Cu, Ag, or Au.

Moreover, in order to improve adhesiveness with a silver particle sintered layer, the 1st to-be-joined body and / or the 2nd to-be-joined body may be surface-treated. Examples of the surface treatment include dry treatment such as corona treatment, plasma treatment, UV treatment, and electron beam treatment, and a method of providing a primer layer and a conductive paste receiving layer on the object to be joined.

FIG. 3 is a schematic cross-sectional view showing the configuration of a power device that is an example of a metal bonded laminate. In the power device shown in FIG. 3, the lower surface of the power semiconductor chip (second bonded body) 11 and the upper surface of the copper-clad insulating substrate (first bonded body) 13 are bonded by the metal bonding material 12. . The power semiconductor chip 11 has a main body made of Si, SiC, GaN or the like, and Au plating is applied to the lower surface. The metal bonding material 12 is a silver particle sintered layer obtained by firing a metal bonding composition containing silver particles and an organic component. The copper-clad insulating substrate 13 has a Cu layer 13b with Ag plating on both surfaces of a base material 13a made of silicon nitride or the like. The Cu layer 13b may not be subjected to Ag plating.

Under the copper-clad insulating substrate 13, a heat radiating material 14 and a heat sink 15 are attached in order to release heat generated in the power semiconductor chip 11. The arrows in FIG. 3 indicate the heat release path. In addition, a wire bond 16 is attached to the upper portion of the power semiconductor chip 11 in order to supply power to the power semiconductor chip 11.

The metal bonding material 12 composed of the silver particle sintered layer can firmly bond the power semiconductor chip 11 to the copper-clad insulating substrate 13 mechanically, electrically, and thermally. When the silver particles are nanometer-sized particles, the silver particles can be sintered at a low temperature due to the melting point drop unique to the nanoparticles, and high conductivity and thermal conductivity close to those of the metal foil can be realized. On the other hand, when solder is used as the metal bonding material 12 as in the prior art, the bonding is performed by melting and solidifying the solder. In this case, the bonding temperature of the metal bonding material 12 is the melting point of the solder, and the heat resistance temperature (usable temperature) of the metal bonding material 12 is lower than the melting point of the solder (bonding temperature). For this reason, when it is going to raise the heat-resistant temperature of the metal joining material 12, joining temperature will also rise. In the development of power devices, improvement in heat resistance and long-term reliability is required, and a silver particle sintered layer that is superior in reliability at a higher temperature than solder is preferably used. Here, the long-term reliability means that the mechanical properties and the like of the metal joined body are maintained for a long time. For example, the mechanical properties and the like of the metal joined body are unlikely to deteriorate even when a large number of heat cycles are applied. Means that.

The silver particle sintered layer is formed through the following steps (1) to (4) using a metal bonding composition as a raw material, for example.

<Step (1)>
In the said process (1), the composition for metal joining is apply | coated to a 1st to-be-joined body. Here, the term “application” is a concept including a case where the metal bonding composition is applied in a planar shape and a case where the composition is applied (drawn) in a linear shape. The shape of the coating film made of the composition for metal bonding before being applied and fired by heating can be made into a desired shape. Therefore, the metal bonding material (silver particle sintered layer) 12 after sintering by heating may be either planar or linear, and may be discontinuous even if continuous on the first bonded body. There may be.

Examples of the method for applying the metal bonding composition include screen printing (metal mask printing), dispenser method, pin transfer method, dipping, spray method, bar coating method, spin coating method, ink jet method, and application method using a brush. , Casting method, flexo method, gravure method, offset method, transfer method, hydrophilic / hydrophobic pattern method, syringe method and the like.

The viscosity of the metal bonding composition is, for example, preferably in the range of 0.01 to 5000 Pa · S, more preferably in the range of 0.1 to 1000 Pa · S, and still more preferably in the range of 1 to 100 Pa · S. . By setting the viscosity range, a wide range of methods can be applied as a method for applying the metal bonding composition. The viscosity can be adjusted by adjusting the particle diameter of the silver particles, adjusting the content of the organic component, adjusting the blending ratio of each component, adding a thickener, and the like. The viscosity of the metal bonding composition can be measured, for example, with a cone plate viscometer (for example, Rheometer MCR301 manufactured by Anton Paar).

<Step (2)>
In the said process (2), the apply | coated composition for metal joining (coating film) is heat-dried. The metal bonding composition applied to the first object to be bonded usually has a large amount of organic components in order to ensure applicability (printability) and pot life (pot life). When the second bonded body is pressed and sintered by heating, many voids are generated in the silver particle sintered layer to be generated. Therefore, before pressing the second object to be bonded to the metal bonding composition, the metal bonding composition is heated and dried in step (2) to reduce the content of organic components in the metal bonding composition in advance. .

The heating temperature (preliminary drying temperature) in the step (2) is preferably 25 ° C. or higher and 100 ° C. or lower. If it is less than 25 degreeC, the dispersion medium in the composition for metal joining cannot be volatilized efficiently. If the temperature exceeds 100 ° C., the dispersion medium can be sufficiently volatilized, but part of the dispersant adhering to the silver particles may also volatilize, and sintering may start. When the joined body is pressed, it cannot be brought into close contact, and joining without pressure is difficult. A more preferable lower limit of the predrying temperature is 50 ° C., and a more preferable lower limit is 60 ° C. Although the heating time in the said process (2) is not specifically limited, It is preferable to carry out until content of the organic component in the composition for metal joining does not change. The method for performing heat drying in the step (2) is not particularly limited, and for example, a conventionally known oven or the like can be used.

<Step (3)>
In the said process (3), a 2nd to-be-joined body is pressed against the heat-dried composition for metal joining. It is preferable that the second bonded body is pressed with a load of 1 MPa or less. When the pressing load exceeds 1 MPa, there is a concern about damage (surface damage or cracking) to the second bonded body such as the power semiconductor chip 11. The pressing load is preferably 0.05 MPa or more. If the pressing load is less than 0.05 MPa, the contact may be insufficient and may be peeled off. The method for pressing the second object to be bonded in the above step (3) is not particularly limited, and various conventionally known methods can be applied, but a heat-dried composition for metal bonding (dry coating film) A method of uniformly pressurizing is preferred.

<Process (4)>
In the step (4), the metal bonding composition is heated and sintered to form a silver particle sintered layer. In the preheating in the step (2), the dispersion medium mainly volatilizes out of the organic components, and the dispersant and the like attached to the silver particles remain in the metal bonding composition, but the heating in the step (4) Most or all of the organic components in the metal bonding composition are volatilized. In this embodiment, when the metal bonding composition includes a binder component, the binder component is also sintered from the viewpoint of improving the strength of the bonding material and improving the bonding strength between the bonded members. In some cases, the binder component is mainly used to adjust the viscosity of the metal bonding composition for application to various printing methods, and the binder condition may be controlled to remove all the binder component. The silver particle sintered layer should have a small remaining amount of organic component in terms of obtaining high bonding strength, and preferably contains substantially no organic component, but it does not impair the effects of the present invention. A part of may remain.

In addition, the heating in the step (4) not only bonds the silver particles in the metal bonding composition, but also the vicinity of the interface between the first bonded body and the second bonded body and the silver particle sintered layer. Then, metal diffuses between adjacent layers. Thereby, a strong bond is formed between the first bonded body and the silver particle sintered layer and between the second bonded body and the silver particle sintered layer.

In the step (4), the first bonded body and the second bonded body may be bonded while being pressurized, but the first bonded body and the second bonded body are bonded together. It may be bonded under no pressure. Bonding under no pressure is excellent in productivity because pressure and heating are not performed simultaneously. In the case of joining under no pressure, voids are likely to be generated in the silver particle sintered layer due to volatilization of organic components when the metal joining composition is heated and sintered. Since the content of the organic component in the metal bonding composition is adjusted by the preliminary drying in the step (2), the generation of voids is suppressed even when bonded under no pressure, and the silver particles have high bonding strength. A sintered layer (metal bonding material) is obtained.

Although the heating temperature in a process (4) will not be specifically limited if a silver particle sintered layer can be formed, It is preferable that it is 200-300 degreeC. If heating temperature is 200-300 degreeC, an organic component etc. can be removed by evaporation or decomposition | disassembly, preventing the damage to a 1st to-be-joined body and a 2nd to-be-joined body, and high joining strength is obtained. Moreover, when heating, you may raise or lower temperature in steps, and it is preferable to heat up from room temperature. The heating time in the step (4) is not particularly limited, and may be adjusted according to the heating temperature so that the bonding strength can be sufficiently obtained. The method for heating in the step (4) is not particularly limited, and for example, a conventionally known oven or the like can be used. The heating in the step (4) may be performed in an air atmosphere or a nitrogen atmosphere.

The silver particle sintered layer is preferably a dense sintered body from the viewpoint of obtaining a mechanically, electrically and thermally strong bonded state, specifically, the porosity of the silver particle sintered layer. Is preferably 20% by volume or less. According to the metal bonding composition of this embodiment, a silver particle sintered layer having a porosity of 5 to 20% by volume can be easily formed even when bonded under no pressure.

The thickness of the silver particle sintered layer is, for example, 10 to 200 μm, and more preferably 20 to 100 μm. The thickness of the silver particle sintered layer can be easily controlled by the thickness of the coating film.

The use of the metal bonded laminate according to the present embodiment is not particularly limited, but when the metal bonded laminate is a power semiconductor element (power device), it can be used for an electric control device. An electric control device including the metal bonded laminate according to the present invention is also an embodiment of the present invention. The electric control device is used for electric control (power switching) in fields such as in-vehicle, electric railway, industrial, consumer (home appliance), and electric power (power generation).

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail about this invention, this invention is not limited only to these Examples.

<Example 1>
While sufficiently stirring 2.0 g of 3-methoxypropylamine with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The resulting viscous material was allowed to react in a thermostatic bath, and then 10 g of levulinic acid was added for further reaction to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then nanosilver particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more. The amount of the obtained nano silver particles was 2.1 g. The obtained nano silver particles and micron silver particles (manufactured by Fukuda Metal Foil Powder Co., Ltd., Ag-HWQ2.5) are mixed at a mass ratio of 7: 3, and hexyl carbitol (dispersion medium) and ricinoleic acid (additives) are mixed. ) Is mixed at a ratio of 9: 1 so that the mass ratio of the total amount of nanosilver particles and micron silver particles to the mixture is 9: 1 and stirred to obtain a composition for metal bonding. It was.

<Example 2>
A metal bonding composition was prepared in the same manner as in Example 1 except that the mixing ratio of nano silver particles and micron silver particles was changed to 8: 2.

<Example 3>
A metal bonding composition was prepared in the same manner as in Example 1 except that the mixing ratio of nano silver particles and micron silver particles was changed to 9: 1.

<Example 4>
While sufficiently stirring 2.0 g of 3-methoxypropylamine with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The resulting viscous material was allowed to react in a thermostatic bath, and then 10 g of levulinic acid was added for further reaction to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then nanosilver particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more. The amount of the obtained nano silver particles was 2.1 g. Further, while stirring 5.0 g of 3-methoxypropylamine, 0.5 g of dodecylamine and 6.0 g of diglycolamine with a magnetic stirrer, 4.5 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put into a thermostat and reacted to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then submicron silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more. The amount of submicron silver particles obtained was 3.0 g. The obtained nano silver particles and submicron silver particles were mixed at a mass ratio of 5: 5, and a mixed liquid in which hexyl carbitol (dispersion medium) and ricinoleic acid (additive) were mixed at 9: 1 was combined with nano silver particles. Were added so that the mass ratio of the total amount of the submicron silver particles and the mixed solution was 9: 1, and the mixture was stirred and mixed to obtain a metal bonding composition.

<Example 5>
It was carried out in the same manner as in Example 4 except that (1) tensile test and (2) a method for producing a metal bonded laminate and measurement of bonding strength, which will be described later, were set to a maximum firing temperature of 250 ° C.

<Example 6>
While thoroughly stirring 3.0 g of 3-methoxypropylamine with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The viscous material obtained was allowed to react in a thermostat, and then 9 g of dodecylamine was added for further reaction to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then nanosilver particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more. The amount of the obtained nano silver particles was 2.1 g. Further, while stirring 5.0 g of 3-methoxypropylamine, 0.5 g of dodecylamine and 10.0 g of diglycolamine with a magnetic stirrer, 4.5 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was allowed to react in a thermostatic bath, and then 15 g of dodecylamine was added for further reaction to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then submicron silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more. The amount of submicron silver particles obtained was 3.0 g. The obtained nanosilver particles and submicron silver particles were mixed at a mass ratio of 4: 6, and a mixed liquid in which hexyl carbitol (dispersion medium) and ricinoleic acid (additive) were mixed at 9: 1 was combined with nanosilver particles. Were added so that the mass ratio of the total amount of the submicron silver particles and the mixed solution was 9: 1, and the mixture was stirred and mixed to obtain a metal bonding composition.

<Example 7>
While thoroughly stirring 5.0 g of 3-methoxypropylamine with a magnetic stirrer, 3.0 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put into a thermostat and reacted to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then nanosilver particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more. The amount of the obtained nano silver particles was 2.0 g. Further, while sufficiently stirring 15.0 g of diglycolamine with a magnetic stirrer, 4.5 g of silver oxalate was added to increase the viscosity. The obtained viscous substance was put into a thermostat and reacted to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then submicron silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more. The amount of submicron silver particles obtained was 3.0 g. The obtained nanosilver particles and submicron silver particles were mixed at a mass ratio of 4: 6, and a mixed liquid in which hexyl carbitol (dispersion medium) and ricinoleic acid (additive) were mixed at 9: 1 was combined with nanosilver particles. Were added so that the mass ratio of the total amount of the submicron silver particles and the mixed solution was 9: 1, and the mixture was stirred and mixed to obtain a metal bonding composition.
Note that, in the firing atmosphere described later in (1) tensile test and (2) measurement method of metal junction laminate and measurement of bonding strength, nitrogen was passed to reduce the oxygen concentration to 300 ppm or less.

<Comparative Example 1>
A metal bonding composition was prepared in the same manner as in Example 1 except that the mixing ratio of nano silver particles and micron silver particles was changed to 6: 4.

<Comparative Example 2>
A metal bonding composition was prepared in the same manner as in Example 1 except that Solsperse 54000 (manufactured by Nippon Lubrizol Co., Ltd.) was used instead of ricinoleic acid.

[Evaluation test]
The following evaluation tests were conducted using the metal bonding compositions prepared in the examples and comparative examples. The results are shown in Table 1.

(A) Measurement of average particle diameter of silver particles From a photograph taken at 200,000 times using a scanning electron microscope (model number: S4800) manufactured by Hitachi, an arithmetic average value of particle diameters of about 50 to 100 particles is obtained. The average particle diameter of nano silver particles, submicron silver particles, and micron silver particles was obtained by the calculation method.

(B) Measurement of content of organic component Using a thermal analyzer (differential thermobalance: TG-DTA) manufactured by Rigaku Corporation, a sample of 20 mg of a metal bonding composition was heated in the atmosphere at a rate of temperature increase of 10 ° C / min. The temperature was raised to 550 ° C. and the volatile content at that time was defined as the content of the organic component.

(1) Tensile test The composition for metal joining was printed on the slide glass using the dumbbell-shaped No. 7 type metal mask (plate thickness 90 micrometers) prescribed | regulated to JISK6251. As preliminary drying, the printed metal bonding composition was placed in an oven set at 70 ° C. and dried for 30 minutes. A slide glass was placed on the dried metal bonding composition and placed in a reflow furnace (manufactured by Shin Apex Co., Ltd.) for firing treatment. The firing process in the reflow furnace was performed in an air atmosphere, heated from room temperature to a maximum temperature of 275 ° C. at a heating rate of 3.8 ° C./min, and then held at 275 ° C. for 60 minutes. During the firing treatment, no pressure was applied and no pressure was applied. The fired metal bonding composition was taken out of the reflow furnace and then peeled off from the slide glass to obtain a test piece for a tensile test.

The tensile test was performed with a universal tensile tester 5969 manufactured by Instron at a measurement speed of 0.72 mm / min. The tensile breaking stress and breaking elongation (strain) when the test piece broke were measured. In addition, the slope in the range of 0.05 to 0.25% of the strain in the obtained stress-strain curve (SS curve) was calculated from an approximate expression and used as the Young's modulus.

(2) Preparation method of metal bonded laminate and measurement of bonding strength Silver plated DBC substrate (area: 30 mm × 40 mm, cross-sectional configuration: Cu plate / SiN substrate / Cu plate = 0.2 mm thickness / 0.32 mm thickness / The metal bonding composition was applied to an 11 mm square using a metal mask (plate thickness: 90 μm). As preliminary drying, the applied metal bonding composition was placed in an oven set at 70 ° C. and dried for 30 minutes. On the dried metal bonding composition, a Si chip (bottom area: 5 mm × 5 mm or 10 mm × 10 mm) subjected to gold sputtering was laminated and pressed at 0.2 MPa. And the obtained laminated body was put into the reflow furnace (made by Shin Apex), and the baking process was performed. The firing process in the reflow furnace was performed in an air atmosphere. After the temperature was increased from room temperature to a maximum temperature of 275 ° C. at a temperature increase rate of 3.8 ° C./min, the temperature was raised at 275 ° C. for 60 minutes. During the firing treatment, no pressure was applied and no pressure was applied. After the completion of the firing treatment, a metal bonded laminate was obtained in which a Si chip subjected to gold sputtering was bonded onto a silver-plated DBC substrate with a metal bonding material made of a sintered metal bonding composition.

The bond strength of the metal bonded laminate was measured using a bond tester (manufactured by Reska) at room temperature. As the test piece, a laminate of 5 mm × 5 mm Si chips was used. The load cell used for the bond tester is 100 kgf, and the upper limit of measurement when a 5 mm × 5 mm chip is used is 40 MPa.

(3) Measurement of Void Ratio The metal bonded laminate obtained in (2) above was subjected to an ultrasonic flaw detector manufactured by Nippon Kraut Kramer Co., Ltd. (ultrasonic frequency: 80 MHz, probe diameter: φ3 mm, focal length PF = 10 mm), voids were confirmed. Fine adjustment was made so that the reflection peak at the joint interface was highest, and the measurement was performed with the material sound velocity = Si: 9600 mm / s and Gain = 65 dB. The threshold value of the reflection intensity was 55%, and more than that was regarded as a void. The void area obtained by binarization with the threshold was calculated using software, and the void ratio was calculated. In addition, as a test piece, what laminated | stacked Si chip of 10 mm x 10 mm was used.

(4) Heat cycle test The metal bonded laminate obtained in the above (2) is put in a thermal shock tester (manufactured by Hutec) and held at -40 ° C and 200 ° C for 10 minutes, respectively. It was taken out after 1000 cycles. After the removal, the void ratio in the above (3) was measured, and the amount of increase in the void ratio with respect to 0 cycle (initial void ratio) was calculated. In addition, as a test piece, what laminated | stacked Si chip of 10 mm x 10 mm was used.

(5) About printability of the printable metal bonding composition, printing is performed with a hand-printed printing press using a plastic squeegee (manufactured by Toyo Giken Co., Ltd.) and a metal mask plate (manufactured by Murakami Co., Ltd.), and evaluated according to the following criteria. did.
◯: Good △: Printing is possible, but stringing occurs x: High viscosity, not printing

(6) About the pot life of the composition for pot life metal joining, it printed with the hand-printing printer similarly to said (5) evaluation of printability, and evaluated by the following references | standards.
◯: Printing is possible after leaving for 5 hours in the released state. Δ: Printing is possible after leaving for 1 to 4 hours in the released state. ×: Printing is not possible after leaving for 1 hour in the released state.

As can be seen from Table 1, all of the metal bonding compositions of Examples 1 to 7 had a tensile rupture stress of 100 MPa or more when fired at 275 ° C., and were excellent in printability and pot life. . It was confirmed that all of the metal bonded laminates produced using such a metal bonding composition have a bonding strength measurement value of 40 MPa, which is the upper limit of measurement, and a high bonding strength of 40 MPa or more. Moreover, although the heat cycle test was implemented about the metal joining laminated body produced using the composition for metal joining of Examples 1-7, the void rate after a test (= initial void rate + void increase amount after a heat cycle) All are 40% or less, and it was confirmed that they have high bonding reliability.

On the other hand, the metal bonding compositions of Comparative Examples 1 and 2 were produced using the metal bonding compositions of Comparative Examples 1 and 2 because the tensile fracture stress of the coating when fired at 275 ° C. was less than 100 MPa. When the heat cycle test was implemented about the metal joining laminated body, the void rate rose significantly after the test and exceeded 40%. This is thought to be because cracks were generated by the heat cycle test. In addition, the metal bonded laminate produced using the metal bonding composition of Comparative Example 2 had a high void ratio after the test of 75% and a low bonding strength of 31 MPa.

DESCRIPTION OF SYMBOLS 11 Power semiconductor chip 12 Metal bonding material 13 Copper-clad insulating substrate 13a Base material 13b Cu layer 14 Heat dissipation material 15 Heat sink 16 Wire bond 51, 53 Slide glass 52 Metal bonding composition 54 Test piece

Claims (7)

A metal bonding composition used for baking and bonding metal surfaces,
The metal bonding composition contains silver particles and a dispersion medium,
The silver particles include nanoparticles having a particle size of 1 to 99 nm, submicron particles having a particle size of 100 to 999 nm, and / or micron particles having a particle size of 1 to 999 μm,
A composition for metal bonding, wherein the film has a tensile breaking stress of 100 MPa or more when fired at 275 ° C. The metal bonding composition according to claim 1, wherein the silver particles include the nanoparticles and the submicron particles. The metal bonding composition according to claim 2, wherein a mass ratio of the nanoparticles to the submicron particles is 4: 6 to 7: 3. A metal bonded laminate including a metal bonding material for bonding the first metal surface and the second metal surface,
The said metal joining material is a sintered compact of the composition for metal joining in any one of Claims 1-3, The metal joining laminated body characterized by the above-mentioned. 5. The metal bonded laminate according to claim 4, wherein at least one of the first metal surface and the second metal surface is a surface of a base material or a plating layer made of Cu, Ag, or Au. body. 6. The metal bonded laminate according to claim 4, wherein the first metal surface is a part of a semiconductor chip, and the second metal surface is a part of a substrate. An electric control device comprising the metal bonded laminate according to any one of claims 4 to 6.

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