TW201910458A - Composition for metal bonding, metal bonded laminate and electric control device - Google Patents

Abstract

The present invention provides: a composition for metal bonding, which is suitable for the formation of a metal bonded material that exhibits excellent durability in terms of a thermal load that is applied thereto during a heat cycle test and the like; a metal bonded laminate wherein bonding of metal surfaces is achieved by firing the above-described composition for metal bonding; and an electric control device. A composition for metal bonding according to the present invention is used for the purpose of bonding metal surfaces by means of firing; and this composition for metal bonding contains silver particles and a dispersion medium. The silver particles comprise nanoparticles that have particle diameters of 1-99 nm, and submicron particles that have particle diameters of 100-999 nm and/or micron particles that have particle diameters of 1-999 [mu]m. A film of this composition for metal bonding fired at 275 DEG C has a tensile stress at break of 100 MPa or more.

Description

Metal bonding composition, metal bonded laminate, and electric control machine

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

In order to perform mechanical, electrical, and/or thermal bonding of the metal parts, a bonding material such as solder, a conductive adhesive, a silver paste, or an anisotropic conductive film is used. These joining materials are used not only for joining metal parts but also for joining ceramic parts, resin parts, and the like. Examples of the use of the bonding material include a use of bonding a light-emitting element such as a light emitting diode (LED) to a substrate, and bonding the semiconductor wafer to the substrate, and further bonding the substrates to the heat release. Use on components, etc. For example, Patent Document 1 to Patent Document 3 can be cited as a prior art document relating to a bonding material.

Patent Document 1 discloses a bonding composition which is a bonding composition containing inorganic particles and an organic component, and is characterized in that the inorganic particles exceed an inorganic substance constituting the inorganic particles with an increase in temperature. Linear expansion coefficient and irreversible expansion.

Patent Document 2 discloses a bonding material comprising two kinds of different polar solvents including silver particles, a low boiling point solvent having a boiling point of 100 ° C to 217 ° C, and a high boiling point solvent of 230 ° C to 320 ° C, and having a phosphate ester. The bonding material of the dispersant of the base, the silver particles comprising, as the main silver particles, nano silver particles coated with a carboxylic acid having 6 or less carbon atoms and having an average primary particle diameter of 10 nm to 30 nm, and as a sub-silver particle The nano silver particles coated with a carboxylic acid having 6 or less carbon atoms and having an average primary particle diameter of 100 nm to 200 nm and the secondary primary particles having a secondary primary particle diameter of 0.3 μm to 3.0 μm, and the bonding material is characterized by: The average primary particle diameter is an average value of particle diameters obtained by measuring 200 or more particles by an image software, and the image software is a transmission electron microscope (for transmission with a magnification of 300,000 times). The Electron Microscope (TEM) image was subjected to circular particle analysis to identify each particle, and the content of the silver particles was 95% by mass or more with respect to the amount of all the bonding materials, and the main silver particles were bonded to all of the bonding materials. Amount of 10 mass% to 40 mass%, of the two vehicles, the high-boiling solvent and the low boiling solvent content ratio and the ratio in mass% of 3: 5 to 1: 1.

Patent Document 3 discloses a bonding material comprising: metal submicron particles having an average primary particle diameter (D50 diameter) of 0.5 μm to 3.0 μm and average primary particles measured by a microtrac particle size distribution measuring device. Metal nanoparticles having a diameter of 1 nm to 200 nm and coated with a fatty acid having 6 carbon atoms, and a dispersion medium for dispersing the particles. [Prior Art Document] [Patent Literature]

[Patent Document 1] International Publication No. 2017/006531 [Patent Document 2] Japanese Patent No. 5976684 (Patent Document 3) Japanese Patent No. 5824201

[Problems to be Solved by the Invention] The inventors of the present invention have researched and developed a metal bonding composition containing metal particles in order to produce a metal bonding material having high bonding strength, but may have a heat load applied in a heat cycle test or the like. Cracks are generated in the metal bonding material, and there is room for improvement in durability.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a metal joining composition and a metal bonded laminated body and an electric control device for joining metal faces by firing the metal joining composition. The metal bonding composition is suitable for forming a metal bonding material excellent in durability against a heat load applied in a heat cycle test or the like. [Means for solving the problem]

The inventors of the present invention have conducted various studies on a metal bonding composition which is suitable for forming a metal bonding material excellent in durability against a heat load applied in a heat cycle test or the like, and as a result, it has been found that silver is prepared by blending Particles and dispersion medium combined with nano particles having a particle diameter of 1 nm to 99 nm, submicron particles having a particle diameter of 100 nm to 999 nm, and/or micro particles having a particle diameter of 1 μm to 999 μm as silver particles can improve calcination The tensile fracture stress of the film after the film. In addition, it has been found that the particle size of the silver particles blended in the metal bonding composition, the type of the dispersion medium, and the like can be adjusted so that the tensile breaking stress of the film at the time of firing at 275 ° C is 100 MPa or more. The present invention has been completed by increasing the void ratio (void ratio) due to a heat load applied in a heat cycle test or the like and forming a metal joint excellent in durability.

The metal joining composition of the present invention is a metal joining composition for joining a metal surface by firing, and the metal joining composition contains silver particles and a dispersion medium, and the silver particles include particles. Nanoparticles with a diameter of 1 nm to 99 nm, submicron particles with a particle size of 100 nm to 999 nm, and/or microparticles with a particle size of 1 μm to 999 μm, and tensile fracture of the film when calcined at 275 °C The stress is 100 MPa or more.

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

The metal bonded laminated body of the present invention is a metal bonded laminated body including a metal joining material in which a first metal surface and a second metal surface are joined, and the metal joining material is a metal joining composition of the present invention. Sintered body.

Preferably, at least one of the first metal surface and the second metal surface is a surface of a substrate or a plating layer containing Cu, Ag or Au.

Preferably, the first metal face is part of a semiconductor wafer and the second metal face is part of the substrate.

The electric control machine of the present invention is characterized by comprising the metal bonded laminate of the present invention. [Effects of the Invention]

According to the present invention, there is provided a metal joining composition and a metal bonded layered body and an electric control device which are joined by firing the metal joining composition, wherein the metal joining composition is suitable A metal bonding material excellent in durability against a heat load applied in a heat cycle test or the like is formed.

The metal bonding composition of the present embodiment is a metal bonding composition for firing and bonding a metal surface, and the metal bonding composition contains silver particles and a dispersion medium, and the silver particles include Nanoparticles having a particle diameter of 1 nm to 99 nm, submicron particles having a particle diameter of 100 nm to 999 nm, and/or microparticles having a particle diameter of 1 μm to 999 μm, and stretching of the film at 275 ° C for calcination The fracture stress is 100 MPa or more.

The tensile fracture stress of the film when the metal bonding composition is fired at 275 ° C is 100 MPa or more. The calcination of the film can be carried out under no pressure. Further, the firing time of the film is preferably 60 minutes or more. When the tensile breaking stress is less than 100 MPa, 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, and thus cracks are severely generated in the metal joint. The upper limit of the tensile fracture stress is not particularly limited and may be, for example, 500 MPa.

Hereinafter, specific examples of the method for measuring the tensile fracture stress of the film will be described with reference to (a) to (c) of FIG. 1 and FIG. (a) to (c) of FIG. 1 are flowcharts for explaining a method of producing a test piece for measurement of tensile fracture stress of a metal joining composition. 2 is a schematic plan view showing the shape and size (unit: mm) of a test piece for measuring the tensile fracture stress of the metal joining composition.

(Method for Measuring Tensile Breaking Stress) (1) As shown in (a) of Fig. 1, a dumbbell-shaped No. 7 shape prescribed in Japanese Industrial Standards (JIS) K 6251 is used (refer to the figure). The metal mask (plate thickness: 90 μm) of 2) was printed on the slide glass 51 by the metal bonding composition 52. (2) As pre-drying, the printed metal bonding composition 52 was placed in an oven set at 70 ° C and dried for 30 minutes. (3) As shown in Fig. 1 (b), the glass slide 53 is placed on the dried metal bonding composition 52 (portion surrounded by a broken line in Fig. 2), and placed in a reflow furnace (new Calcination treatment is carried out in a company manufactured by Shinapex. The calcination treatment in the reflow furnace was carried out under an atmospheric environment, and the temperature was raised 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. At the time of the calcination treatment, no pressurization was performed and no pressurization was performed. In addition, the term "no pressurization" means that the bonded body such as a semiconductor wafer is not bonded by a load other than the weight of the bonded body. In the present measurement method, the actual bonded state is reproduced by placing the slide glass 53 (position is joined) Body state). (4) As shown in (c) of FIG. 1, the calcined metal bonding composition 52 was taken out from the reflow furnace, and then peeled off from the slide glass 51 and the slide glass 53 to prepare a tensile test. Test piece 54. (5) The tensile test was carried out using a universal tensile tester 5969 manufactured by Instron Co., Ltd. at a measurement speed of 0.72 mm/min. The tensile breaking stress at the time of breakage of the test piece 54 was measured.

The tensile stress at break was measured for a film which was calcined at 275 °C. When the metal bonding composition is fired, the first dispersion medium (solvent) is volatilized or decomposed to be volatilized, and the organic component other than the dispersion medium such as a dispersant used for dispersion of the silver particles is volatilized or decomposed and volatilized, and silver particles are evaporated. Since the low-temperature sinterability is excellent, when it is baked to 275 ° C, the removal of the organic component in the metal bonding composition and the sintering of the silver particles by necking (partial welding) of the particles can be quickly performed. The metal bonding composition of the present embodiment is preferably used by calcination 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%, still more preferably 11% to 12%. The mass reduction rate can be calculated from the results 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 formula (A), it is considered that the tensile fracture stress can be increased as the crystal grain size is decreased. Σy=σ ₀ +k/√d (A) σy: yield stress, σ ₀ : frictional stress, k: impedance coefficient of sliding relative to the grain boundary, d: average crystal grain size

Here, as a method of reducing the crystal grain size, a method of including nano particles in the silver particles blended in the metal bonding composition, or a method of increasing the ratio thereof, or a method of shortening the time of sintering of the silver particles may be mentioned. . When the ratio of the nanoparticles in the silver particles blended in the metal bonding composition is increased, the neck portions of the silver particles can be increased. When the time during which the sintering of the silver particles occurs is shortened, the progress of the fusion of the silver particles can be suppressed. The shortening of the time during which the sintering of the silver particles occurs is also achieved by delaying the removal of the organic component blended in the composition for metal bonding.

As described above, the method of adjusting the tensile fracture stress of the film at the time of firing at 275 ° C is preferably a method of increasing the ratio of the nanoparticles in the silver particles blended in the composition for metal bonding, or changing the dispersion. A method of dispersing or dispersing a medium. As the dispersant, it is preferred to volatilize (=particle sintering) at less than 275 °C. As for the dispersion medium, it is preferred to volatilize the silver particles before sintering. Further, it is preferred to reduce the amount of remaining solvent before the calcination step.

The metal bonding composition is not particularly limited as long as it contains silver particles and a dispersion medium, and is preferably in a paste form for easy application. Further, in addition to the silver particles, particles having a higher ionization sequence than hydrogen, that is, particles such as gold, copper, platinum, or palladium may be used in combination to prevent migration.

The silver particles comprise nano particles (also referred to as nano silver particles) having a particle diameter of 1 nm to 99 nm, and submicron particles having a particle diameter of 100 nm to 999 nm and/or micron particles having a particle diameter of 1 μm to 999 μm. Particles (also known as micron silver particles). The nanoparticle may be dispersed in the metal bonding composition separately from the submicron particles or the microparticles, or may be attached to at least a part of the surface of the submicron particles or the microparticles. Further, it is preferable that the nanoparticle, the submicron particle, and the microparticle have peaks having independent particle size distributions.

The average particle diameter of the silver particles can be measured by dynamic light scattering (Dynamic Light Scattering), small-angle X-ray scattering, or wide-angle X-ray diffraction, and is suitable for measuring the particle diameter of the microparticles. In the present specification, the "average particle diameter" means a dispersed median diameter. As another method of measuring the average particle diameter, a method of calculating an arithmetic mean value of particle diameters of 50 to 100 particles based on a photograph taken using a scanning electron microscope or a transmission electron microscope is used. The particle size of the particles is suitable.

The average particle diameter of the nanoparticles is not particularly limited as long as it does not detract from the effects of the present invention. When a nanoparticle having an average particle diameter of 1 nm or more is used as the silver particle having a small diameter, a metal bonding composition capable of forming a good metal bonding material is obtained, and the production cost of the silver particle is not high and practical. Further, when it is 99 nm or less, the dispersibility of the nanoparticles is less likely to change with time.

Preferably, the silver particles comprise nano particles and submicron particles, and the mass ratio of the nano particles to the submicron particles contained in the silver particles is more preferably 4:6 to 7:3. When the mass ratio of the nanoparticle to the submicron particle is less than 4:6 (the mass ratio of the nanoparticle is less than 40%), the particles are hardly connected to each other, and the bonding strength between the particles (corresponding to tensile strength) is lowered, so that it exists in Concerns about cracking at an early stage in the thermal cycle test. When the mass ratio of the nanoparticle to the submicron particle exceeds 7:3 (the mass ratio of the nanoparticle exceeds 70%), the shrinkage at the time of firing becomes large, and pores (voids) in the sintered body of the metal bonding composition are present. Concerns that the proportion is getting too high.

The silver particles preferably comprise nanoparticles and microparticles, and the mass ratio of the nanoparticles to the microparticles contained in the silver particles is preferably from 7:3 to 8:2. If the mass ratio of the nanoparticle to the microparticle is less than 7:3 (the mass ratio of the nanoparticle is less than 70%), there is a fear that cracking occurs early in the heat cycle test due to a decrease in tensile strength. When the mass ratio of the nanoparticle to the microparticle is more than 8:2 (the mass ratio of the nanoparticle exceeds 80%), the ratio of pores (voids) in the sintered body of the metal bonding composition may become excessively high.

The average particle diameter of the microparticles is not particularly limited as long as it does not impair the effects of the present invention, and is preferably 1 μm to 20 μm. By using microparticles having an average particle diameter of 1 μm to 20 μm, volume shrinkage due to sintering can be reduced, and a homogeneous and dense joint material can be obtained. When the submicron particles having an average particle diameter of less than 1 μm are used as the silver particles having a large diameter, the sintering is performed at a low temperature. However, when the sintering of the particles progresses, the volume shrinkage increases as the average particle diameter increases, and there is a case where the volume shrinkage increases. The joint body cannot follow the fear of shrinkage of the volume. In this case, defects such as voids are generated in the metal bonding material, and the bonding strength and reliability of the metal bonding material are lowered. On the other hand, when particles having an average particle diameter of more than 20 μm are used, sintering at a low temperature is hardly progressed, and there is a concern that a large void formed between the silver particles remains after sintering. The average particle diameter of the microparticles is more preferably from 1 μm to 10 μm.

The silver particles can be obtained, for example, by mixing a metal ion source with a dispersing agent 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 hardly volatilized during the step of coating the metal bonding composition, and is preferably difficult to volatilize at room temperature.

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

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

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

Examples of the alicyclic hydrocarbons include limonene, dipentene, terpinene, terpinene (also known as terpinene), nesol, and cinene. Orange flavor, terpinolene, terpinolene (also known as terpinolene), phellandrene, menthadiene, terebene, dihydroanimate Dihydrocymene, γ-terpinene (moslene), isodecene, isonene (also known as isoterpene), crithmene, kautschin, leukocholium (cajeputene), Eulimen, pinene, turpentine, menthane, pinane, terpene, cyclohexane, and the like.

The alcohol is a compound containing one or more OH groups in a molecular structure, and examples thereof include an aliphatic alcohol, a cyclic alcohol, and an alicyclic alcohol, and they may be used alone or in combination of two or more. Further, a part of the OH group may be derived from an ethenyloxy group or the like within the range which does not impair the effects of the present invention.

Examples of the aliphatic alcohol include heptanol, octanol (1-octanol, 2-octanol, 3-octanol, etc.), decyl alcohol (1-nonanol, etc.), lauryl alcohol, and fourteen. A saturated or unsaturated C6-30 aliphatic alcohol such as a base alcohol, cetyl alcohol, 2-ethyl-1-hexanol, octadecyl alcohol, hexadecenol or oleyl alcohol.

Examples of the cyclic alcohol include cresol, eugenol, and the like.

Examples of the alicyclic alcohol include a cycloalkanol such as cyclohexanol, terpineol (including an α, β, γ isomer, or a mixture of any of these), and dihydroterpineol. Enol (monoterpene alcohol, etc.), dihydroterenol, myrtenol, sobrerol, menthol, carveol, perillyl alcohol , pine carveol (pinocarveol), suprepineol, verbufenol (verbenol) and the like.

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

The initial content in the case where the metal bonding composition contains a dispersion medium may be adjusted according to characteristics required for viscosity or the like, and the initial content of the dispersion medium in the metal bonding composition is preferably from 1% by mass to 30% by mass. . When the initial content of the dispersion medium is from 1% by mass to 30% by mass, the effect of adjusting the viscosity in a range that is easy to use as a metal bonding composition can be obtained. A more preferable initial content of the dispersion medium is from 1% by mass to 20% by mass, and further preferably, the initial content is from 1% by mass to 15% by mass.

The dispersion medium to be formulated in the metal bonding composition is preferably hexyl carbitol or butyl carbitol acetate. It is preferred to contain 50% by mass or more of hexyl carbitol in the dispersion medium. Further, the metal component for metal bonding preferably has a solid content concentration of 88% by mass to 93% by mass. When these conditions are satisfied, the viscosity can be adjusted to an appropriate range without lowering the bonding strength or the porosity. Therefore, a metal bonding composition excellent in printability by a metal mask can be obtained. Further, since the stability of the viscosity over time can be ensured, the pot life of the metal bonding composition can be prolonged.

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

Examples of the additive for improving the dispersibility of the silver particles include an amine, a carboxylic acid, a polymer dispersant, and an unsaturated hydrocarbon. The amine or the carboxylic acid is adsorbed to the surface of the silver particles with a moderate strength and prevents the silver particles from coming into contact with each other, thereby contributing to the stability of the silver particles in the storage state. The additive adsorbed on the surface of the silver particles is transferred and/or volatilized from the surface of the silver particles upon heating, whereby it is considered that the silver particles are promoted to be welded to each other and to the substrate. The polymer dispersant is allowed to adhere to at least a part of the silver particles, whereby the low-temperature sinterability of the silver particles is not lost, and the dispersion stability can be maintained.

It is preferred that the 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 coated with an organic protective layer containing an organic component), and the organic component (organic protective layer) contains an amine. It is preferable to provide an organic protective layer on at least a part of the surface of the metal particles to stably store particles of a nanometer size showing a melting point lowering ability. Here, since the amine is adsorbed on the surface of the silver particles with a moderate strength, it can be suitably used as an organic protective layer.

The amine is not particularly limited, and for example, an alkylamine such as an oleylamine, a butylamine, a pentylamine, a hexylamine, a hexylamine or an octylamine (a linear alkylamine or a side chain) may be used. An alkane such as N-(3-methoxypropyl)propane-1,3-diamine, 2-methoxyethylamine, 3-methoxypropylamine or 3-ethoxypropylamine a oxamine; a cycloalkylamine such as a cyclopentylamine or a cyclohexylamine; a primary amine such as an allylamine such as aniline; or a dipropylamine, dibutylamine, piperidine or hexamethyleneimine; A tertiary amine, or a tertiary amine such as tripropylamine, dimethylpropanediamine, cyclohexyldimethylamine, pyridine or quinoline.

The amine is preferably an amine having a carbon number of about 2 to 20, 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 the amine having 4 to 7 carbon atoms is transferred and/or volatilized at a relatively low temperature, the low-temperature sinterability of the silver particles can be sufficiently utilized. Further, the amine may be linear, may be branched, or may have a side chain.

Further, it is considered that the organic components are changed to an anion or a cation when chemically or physically bonded to the silver particles. In the present embodiment, ions or complexes derived from the organic components are also included in the embodiment. Among the organic ingredients.

The amine may also 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. Further, the amines may be used alone or in combination of two or more. Further, the boiling point at normal temperature is preferably 300 ° C or lower, more preferably 250 ° C or lower.

As the carboxylic acid, a compound having at least one carboxyl group can be widely used, and examples thereof include formic acid, oxalic acid, acetic acid, caproic acid, acrylic acid, octanoic acid, levulinic acid, oleic acid and the like. A carboxyl group of a part of the carboxylic acid may also form a metal ion and a salt. Further, the metal ions may contain two or more kinds of metal ions.

The carboxylic acid may be a compound containing a functional group other than a carboxyl group such as an amine group, a hydroxyl group, an alkoxy group, a carbonyl group, an ester group or a fluorenyl group. In this case, the number of carboxyl groups is preferably at least the number of functional groups other than the carboxyl group. Further, the carboxylic acids may be used alone or in combination of two or more. Further, the boiling point at normal temperature is preferably 300 ° C or lower, more preferably 250 ° C or lower.

Further, the amine forms a guanamine group with the carboxylic acid. The guanamine group is also moderately adsorbed on the surface of the silver particles, and therefore the amide group may be contained in the organic component.

The composition ratio (mass) when the amine and the carboxylic acid are used in combination may be arbitrarily selected in the range of from 1/99 to 99/1, preferably from 20/80 to 98/2, more preferably from 30/70 to 97/3. .

As the polymer dispersant, a commercially available polymer dispersant can be used. As a commercially available polymer dispersant, for example, SOSOLPERS 11200, Sonupas 13940, Sonupas 16000, Sonupas 17000, Sonupas 18000, Sonupas 20000, Sonupas 24000, Sonupas 26000, Sonupas 27000, Sonupas 28000, Sonupas 54000 (above, manufactured by Lubrizol, Japan); Disparbike (DISPERBYK) 142, Despabike 160, Despabike 161, Despabike 162, Despabike 163, Disparbike 166, Despabike 170, Dispa BYK 180, Despabike 182, Despabike 184, Despabike 190, Despabike 2155 (above, BYK-Chemie Japan); Eve Card (EFKA)-46, EFKA-47, EFKA-48, EFKA-49 (above, manufactured by EFKA Chemical Co., Ltd.); polymer 100, polymer 120, polymer 150, polymer 400 , polymer 401, polymer 402, polymer 403, polymer 450, polymer 451, polymer 452, polymer 453 (above, EFKA chemistry) Manufactured by the company); Ajisper PB711, Ajispa PA111, Ajispa PB811, Ajispa PW911 (above, Ajinomoto); Floren DOPA-15B, Floren DOPA-22, Floren DOPA-17, Floren TG-730W, Floren G-700, Floren TG-720W (above, manufactured by Kyoeisha Chemical Industry Co., Ltd.), and the like. From the viewpoints of low-temperature sinterability and dispersion stability, it is preferable to use Sonupas 11200, Sonupas 13940, Sonupas 16000, Sonupas 17000, Sonupas 18000, Sonupa 28000, Sonupas 54000, Despabike 142 or Despabike 2155.

The content of the polymer dispersant is preferably from 0.03 mass% to 15 mass%. When the content of the polymer dispersant is 0.1% by mass or more, the dispersion stability of the obtained metal bonding composition is good, but when the content is too large, the bondability is lowered. From such a viewpoint, a more preferable content of the polymer dispersant is 0.05% by mass to 3% by mass, and a further preferable content is 0.1% by mass to 2% by mass.

Examples of the unsaturated hydrocarbon include ethylene, acetylene, benzene, acetone, 1-hexene, 1-octene, 4-vinylcyclohexene, cyclohexanone, decene alcohol, and allyl alcohol. , oleyl alcohol, 2-palmitoleic acid, petroselinic acid, oleic acid, anti-oleic acid, tianshic acid, ricinoleic acid, linoleic acid , linolelaidic 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 suitably used. The hydroxyl group is easily disposed on the surface of the silver particles, so that aggregation of the silver particles can be suppressed. Examples of the unsaturated hydrocarbon having a hydroxyl group include a terpene alcohol, an allyl alcohol, an oleyl alcohol, a ginsolic acid, ricinoleic acid, gallic acid, and salicylic acid. The unsaturated fatty acid having a hydroxyl group is preferably, for example, tianshi acid, ricinoleic acid, gallic acid, salicylic acid or the like.

The dispersing agent to be blended in the metal joining composition is preferably an amine or a carboxylic acid having a boiling point of from 150 ° C to 300 ° C, and among them, acetopropionic acid is particularly preferably used.

Further, in the range in which the effects of the present invention are not impaired, the organic component may include an oligomer component, a resin component, an organic solvent (a part of the solid component may be dissolved or dispersed), and an interface which functions as a binder. Active agent, thickener, surface tension modifier, and the like.

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

The organic solvent is excluded as the dispersion medium, and examples thereof include methyl alcohol, ethyl alcohol, n-propyl alcohol, 2-propyl alcohol, 1,3-propanediol, and 1,2- Propylene glycol, 1,4-butanediol, 1,2,6-hexanetriol, 1-ethoxy-2-propanol, 2-butoxyethanol, ethylene glycol, diethylene glycol, triethyl Polyethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol having a weight average molecular weight of 200 or more and 1,000 or less, and a polypropylene glycol having a weight average molecular weight of 300 or more and 1,000 or less, N, N-di Methylformamide, dimethylhydrazine, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, glycerin, acetone, etc., which may be used alone or in combination More than one species.

Examples of the thickener include clay minerals such as clay, bentonite, and hectorite, polyester emulsion resins, acrylic emulsion resins, and polyurethane emulsion resins. Emulsions such as segment isocyanate, cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, xanthan gum, melon A polysaccharide such as guar gum 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 may be used, and examples thereof include an alkylbenzenesulfonate and a quaternary ammonium salt. A fluorine-based surfactant is preferred because an effect is obtained with a small amount of addition.

The content of the organic component in the metal bonding composition of the present embodiment is preferably 5% by mass to 50% by mass. When the content is 5% by mass or more, the metal bonding composition tends to have good storage stability. When the content is 50% by mass or less, the metal bonding composition tends to have good conductivity. A more preferable content of the organic component is 5% by mass to 30% by mass, and further preferably a content of 5% by mass to 15% by mass.

The metal joining composition of the present embodiment is used for firing to bond the metal faces. Further, the metal bonded laminate is also an aspect of the invention, the metal bonded laminate comprising a metal bonding material joining the first metal surface and the second metal surface, and the metal bonding material is the metal bonding of the present invention A sintered body of the composition is used. In other words, the metal bonded laminate of the present embodiment is a first joined body having a first metal surface and has a second metal joining material comprising a silver sintered layer obtained by sintering the metal joining composition. The second joined body of the metal surface is joined.

The type of the first to-be-joined body and the second to-be-joined body is not particularly limited, and it is preferably a member having heat resistance that is not damaged by the temperature at the time of heating and sintering of the metal joining composition, and may be rigid ( Rigid) can also be flexible. Further, the shape and thickness of the first joined body and the second joined body are not particularly limited, and can be appropriately selected.

The type of the metal bonded laminate is not particularly limited, and is, for example, a power semiconductor element (power device). Preferably, the first metal face is part of a semiconductor wafer and the second metal face is part of the substrate. Further, from the viewpoint of obtaining high joint strength, at least one of the first metal surface and the second metal surface is preferably a surface of a base material or a plating layer containing Cu, Ag or Au.

Further, the first joined body and/or the second joined body may be subjected to surface treatment in order to improve adhesion to the sintered layer of silver particles. Examples of the surface treatment include dry treatment such as corona treatment, plasma treatment, ultraviolet (Ultra Violet (UV) treatment, and electron beam treatment, or providing an undercoat layer or a conductive paste receiving layer on the member to be joined. Method etc.

3 is a schematic cross-sectional view showing a configuration of a power device as an example of a metal bonded laminate. In the power device shown in FIG. 3, the lower surface of the power semiconductor wafer (second bonded body) 11 is bonded to the upper surface of the copper-clad insulating substrate (first bonded body) 13 by the metal bonding material 12. The main body of the power semiconductor wafer 11 contains Si, SiC, GaN, or the like, and Au is plated on the lower surface. The metal bonding material 12 is a sintered silver particle layer obtained by firing a composition for metal bonding containing silver particles and an organic component. The copper-clad insulating substrate 13 has a Cu layer 13b plated with Ag on both surfaces of a substrate 13a including tantalum nitride or the like. The Cu layer 13b is sometimes not plated with Ag.

A heat releasing material 14 and a heat sink 15 are attached below the copper clad insulating substrate 13 to discharge heat generated in the power semiconductor wafer 11. The arrows in Fig. 3 indicate the heat release path. Further, a wire bonding wire 16 is attached to the upper portion of the power semiconductor wafer 11 to supply electric power to the power semiconductor wafer 11.

The metal bonding material 12 including the sintered silver particle layer can bond the power semiconductor wafer 11 to the copper-clad insulating substrate 13 mechanically, electrically, and thermally. In the case where the silver particles are nanoparticles having a nanometer size, the melting point which is peculiar to the nanoparticles can be lowered and sintered at a low temperature, and high conductivity or thermal conductivity close to the metal foil can be achieved. On the other hand, as in the case of using the solder as the metal bonding material 12 as before, bonding is performed by melting the solder and solidifying it. In this case, the bonding temperature of the metal bonding material 12 is the melting point of the solder, and the heat resistant temperature (temperature that can be used) of the metal bonding material 12 is lower than the melting point (bonding temperature) of the solder. Therefore, if the heat resistance temperature of the metal bonding material 12 is to be increased, the bonding temperature is also increased. In the development of a power device, heat resistance or long-term reliability is required to be improved, and a silver particle sintered layer excellent in reliability at a high temperature compared to solder is preferably used. Here, the long-term reliability means that the mechanical properties of the metal joined body are maintained for a long period of time, and for example, it means that the mechanical properties of the metal joined body are hard to be lowered even if a plurality of thermal cycles are applied.

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

<Step (1)> In the step (1), a composition for metal bonding is applied to the first to-be-joined body. Here, the term "coating" includes the case where the metal bonding composition is applied in a planar shape, and the coating (drawing) is linear. The shape of the coating film containing the metal bonding composition in the state before being coated and calcined by heating can be set to a desired shape. Therefore, the metal bonding material (silver particle sintered layer) 12 sintered by heating may be either planar or linear, and may be discontinuous or discontinuous in the first joined body.

As a method of applying the metal bonding composition, for example, screen printing (metal mask printing), dispenser method, pin transfer method, dipping, spraying, and bar coating can be used. The method, the spin coating method, the inkjet method, the coating method using a brush, a casting method, a flexographic method, a gravure method, a flat plate method, a transfer method, a hydrophilic hydrophobic pattern method, a syringe method, and the like are suitably selected.

The viscosity of the metal bonding composition is, for example, preferably in the range of 0.01 Pa·S to 5000 Pa·S, more preferably in the range of 0.1 Pa·S to 1000 Pa·S, and still more preferably 1 Pa·S to 100 Pa. · The scope of S. By setting this viscosity range, a wide range of methods can be applied as a method of coating a composition for metal bonding. 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, and adding a thickener. The viscosity of the metal bonding composition can be measured, for example, by a cone plate type viscometer (for example, a rheometer MCR301 manufactured by Anton Paar Co., Ltd.).

<Step (2)> In the step (2), the applied metal bonding composition (coating film) is dried by heating. The metal bonding composition applied to the first to-be-joined body generally has a large amount of organic components in order to ensure applicability (printability) and pot life (useable time), and directly presses and heats the second joined body. When sintered, voids (pores) are generated in a large amount in the sintered layer of the generated silver particles. Therefore, before the second joined body is pressed to the metal bonding composition, the metal bonding composition is heated and dried in the step (2), and the content of the organic component in the metal bonding composition is reduced in advance.

The heating temperature (pre-drying temperature) in the step (2) is preferably 25 ° C or more and 100 ° C or less. When it is less than 25 ° C, the dispersion medium in the metal bonding composition cannot be volatilized efficiently. When it exceeds 100 ° C, the dispersion medium can be sufficiently volatilized, but a part of the dispersing agent adhering to the silver particles is volatilized, and there is a fear that sintering starts. In this case, it is difficult to adhere the second joined body when it is pressed. Bonding without pressure is performed. A more preferred lower limit of the pre-drying temperature is 50 ° C, and a preferred lower limit is 60 ° C. The heating time in the step (2) is not particularly limited, and it is preferred that the content of the organic component in the metal bonding composition does not change. The method of performing the heat drying in the step (2) is not particularly limited, and for example, a previously known oven or the like can be used.

<Step (3)> In the step (3), the second joined body is pressed to the heat-dried metal bonding composition. The second joined body is preferably pressed with a load of 1 MPa or less. When the pressing load exceeds 1 MPa, damage (scratch or crack of the surface) may occur in the second joined body of the power semiconductor wafer 11 or the like. The pressing load is preferably 0.05 MPa or more. When the pressing load is less than 0.05 MPa, the adhesion is insufficient and there is a concern that peeling may occur. The method of performing the pressing of the second joined body in the step (3) is not particularly limited, and various conventionally known methods can be applied, and it is preferable to uniformly heat the dried metal joining composition (dry coating film). ) A method of applying pressure.

<Step (4)> In the step (4), the metal bonding composition is heated and sintered to form a silver particle sintered layer. In the preheating of the step (2), the organic component mainly contains a dispersing agent or the like which is volatilized in the dispersion medium and adheres to the silver particles, and remains in the metal bonding composition, and is heated by the step (4) to form a metal bonding component. Most or all of the organic components in the material are volatilized. In the present embodiment, when the metal bonding composition contains a binder component, the binder component is sintered, from the viewpoint of improving the strength of the bonding material and improving the bonding strength between the bonding members. In order to apply to various printing methods, the viscosity of the metal bonding composition is adjusted as a main component of the binder component, and the baking conditions are controlled to remove all the binder components. In the silver particle sintered layer, in terms of obtaining high joint strength, the residual amount of the organic component is preferably small, and it is preferable that the organic component is not substantially contained, and may remain in the range which does not impair the effects of the present invention. Part of the organic ingredients.

Further, by the heating in the step (4), not only the silver particles in the composition for metal bonding are bonded to each other, but also the metal is adjacent to the interface between the first joined body and the second joined body and the sintered layer of the silver particles. The layers spread out. Thereby, a strong bond is formed between the first joined body and the sintered silver particle layer, and between the second joined body and the sintered silver particle layer.

In the step (4), the first joined body and the second joined body may be joined while being pressed, or the first joined body and the second joined body may be joined without pressure. The bonding without pressurization does not simultaneously pressurize and heat, and therefore is excellent in productivity. When the metal component is heated and volatilized, the organic component volatilizes when the metal composition is heated, and the voids are easily formed in the sintered layer of the silver particle. In this embodiment, In the pre-drying of the step (2), the content of the organic component in the metal bonding composition is adjusted, so that the bonding is suppressed even under no pressure, and the sintered layer of silver particles having high bonding strength is obtained. Joint material).

The heating temperature in the step (4) is not particularly limited as long as it can form a sintered layer of silver particles, and is preferably 200 to 300 °C. When the heating temperature is 200 ° C to 300 ° C, damage in the first joined body and the second joined body is prevented, and the organic component or the like can be removed by evaporation or decomposition, and high joint strength can be obtained. Further, when heating is performed, the temperature may be gradually increased or decreased, and it is preferred to raise the temperature from room temperature. The heating time in the step (4) is not particularly limited as long as it is adjusted in accordance with the heating temperature and sufficiently obtaining the joint strength. The method of performing the heating in the step (4) is not particularly limited, and for example, a previously known oven or the like can be used. The heating in the step (4) can be carried out under an atmospheric environment or under a nitrogen atmosphere.

The sintered silver particle layer is preferably a dense sintered body from the viewpoint of obtaining a mechanically, electrically and thermally bonded state. Specifically, the sintered ratio of the silver particle sintered layer is preferably 20% by volume. %the following. According to the metal bonding composition of the present embodiment, the silver particle sintered layer having a void ratio of 5 vol% to 20 vol% can be easily formed even if the bonding is performed without pressure.

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

The use of the metal bonded laminate of the present embodiment is not particularly limited, and when the metal bonded laminate is a power semiconductor element (power device), it can be used for an electrically controlled device. In addition, an electrically controlled machine is also an aspect of the invention, which includes the metal bonded laminate of the present invention. The electric control machine can be used for electric control (power switch) in the fields of vehicles, electric railways, industrial use, people's livelihood (home appliances), and electric power (power generation). [Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited to the examples.

<Example 1> 2.0 g of 3-methoxypropylamine was sufficiently stirred by a magnetic stirrer, and 3.0 g of silver oxalate was added to make it thick. The obtained viscous substance was placed in a thermostatic chamber and allowed to react, and then 10 g of acetaminophen was added and further reacted to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then the nano silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. Repeat this operation again. The amount of nano silver particles obtained was 2.1 g. The obtained nano silver particles and micron silver particles (manufactured by Fukuda Metal Foil Powder Co., Ltd., Ag-HWQ2.5) were mixed at a mass ratio of 7:3, and the total amount of nano silver particles and micro silver particles was A mixed liquid obtained by mixing hexyl carbitol (dispersion medium) and ricinoleic acid (additive) in a ratio of 9:1 was added in a mass ratio of 9:1, and the mixture was stirred and mixed to obtain a metal bonding composition. .

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

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

<Example 4> 2.0 g of 3-methoxypropylamine was sufficiently stirred by a magnetic stirrer to add 3.0 g of silver oxalate to thicken it. The obtained viscous substance was placed in a thermostatic chamber and allowed to react, and then 10 g of acetaminophen was added and further reacted to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then the nano silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. Repeat this operation again. The amount of nano silver particles obtained was 2.1 g. Further, 5.0 g of 3-methoxypropylamine, 0.5 g of dodecylamine and 6.0 g of diethylene glycolamine were sufficiently stirred by a magnetic stirrer, and 4.5 g of silver oxalate was added thereto to thicken it. The obtained viscous substance was placed in a thermostatic chamber and allowed to react to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then the secondary micron silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. Repeat this operation again. The amount of submicron silver particles obtained was 3.0 g. The obtained nano silver particles and the submicron silver particles are mixed at a mass ratio of 5:5, and the hexyl group is added in such a manner that the total mass of the nano silver particles and the submicron silver particles and the mass ratio of the mixed liquid are 9:1. A mixed liquid of carbitol (dispersion medium) and ricinoleic acid (additive) mixed at 9:1 was stirred and mixed to obtain a metal bonding composition.

<Example 5> Example 4 was carried out except that the maximum temperature of calcination in the (1) tensile test and (2) the method for producing the metal bonded laminate and the measurement of the joint strength were 250 ° C. The same goes on.

<Example 6> 3.0 g of 3-methoxypropylamine was sufficiently stirred by a magnetic stirrer to add 3.0 g of silver oxalate to thicken it. The obtained viscous material was placed in a thermostatic chamber and allowed to react, and then 9 g of dodecylamine was added to cause a reaction to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then the nano silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. Repeat this operation again. The amount of nano silver particles obtained was 2.1 g. Further, 5.0 g of 3-methoxypropylamine, 0.5 g of dodecylamine and 10.0 g of diethylene glycolamine were sufficiently stirred by a magnetic stirrer, and 4.5 g of silver oxalate was added thereto to thicken it. After the obtained viscous substance was placed in a thermostatic chamber and allowed to react, 15 g of dodecylamine was added and further reacted to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then the secondary micron silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. Repeat this operation again. The amount of submicron silver particles obtained was 3.0 g. The obtained nano silver particles and the submicron silver particles are mixed at a mass ratio of 4:6, and the hexyl group is added in such a manner that the total mass of the nano silver particles and the submicron silver particles and the mass ratio of the mixed liquid are 9:1. A mixed liquid of carbitol (dispersion medium) and ricinoleic acid (additive) mixed at 9:1 was stirred and mixed to obtain a metal bonding composition.

<Example 7> 5.0 g of 3-methoxypropylamine was sufficiently stirred while being stirred by a magnetic stirrer, and 3.0 g of silver oxalate was added thereto to thicken it. The obtained viscous substance was placed in a thermostatic chamber and allowed to react to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then the nano silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. Repeat this operation again. The amount of nano silver particles obtained was 2.0 g. Further, 15.0 g of diglycolamine was sufficiently stirred by a magnetic stirrer, and 4.5 g of silver oxalate was added to thicken it. The obtained viscous substance was placed in a thermostatic chamber and allowed to react to obtain a suspension. Next, in order to replace the dispersion medium of the suspension, methanol was added and stirred, and then the secondary micron silver particles were precipitated and separated by centrifugation, and the supernatant was discarded. Repeat this operation again. The amount of submicron silver particles obtained was 3.0 g. The obtained nano silver particles and the submicron silver particles are mixed at a mass ratio of 4:6, and the hexyl group is added in such a manner that the total mass of the nano silver particles and the submicron silver particles and the mass ratio of the mixed liquid are 9:1. A mixed liquid of carbitol (dispersion medium) and ricinoleic acid (additive) mixed at 9:1 was stirred and mixed to obtain a metal bonding composition. In the firing test in the (1) tensile test and (2) the method for producing the metal bonded laminate and the measurement of the joint strength, nitrogen gas was passed through and the oxygen concentration was set to 300 ppm or less.

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

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

[Evaluation Test] The metal bonding composition prepared in the examples and the comparative examples was used and subjected to the following evaluation test. The results are shown in Table 1.

(A) Measurement of Average Particle Diameter of Silver Particles The average particle diameters of the nano silver particles, the submicron silver particles, and the micro silver particles were obtained by using a scanning electron microscope (Model: S4800) manufactured by Hitachi, Ltd. The photograph taken at 200000 times calculates the arithmetic mean of the particle sizes of 50 to 100 particles.

(B) Measurement of the content of the organic component 20 mg of a sample of the composition for metal bonding in the atmosphere using a thermal analyzer (differential thermobalance: TG-DTA) manufactured by Rigaku Co., Ltd. at a temperature elevation rate of 10 ° C The temperature was raised to 550 ° C in /min, and the volatile component at this time was made into the content of the organic component.

(1) Tensile test The metal bonding composition was printed on a glass slide using a dumbbell-shaped 7-shaped metal mask (thickness: 90 μm) prescribed in JIS K 6251. As pre-drying, the printed metal bonding composition was placed in an oven set at 70 ° C and dried for 30 minutes. The slide glass was placed on the dried metal bonding composition, placed in a reflow furnace (manufactured by Shinapex Co., Ltd.), and calcined. The calcination treatment in the reflow furnace was carried out under an atmospheric environment, and the temperature was raised from room temperature to a maximum temperature of 275 ° C at a temperature increase rate of 3.8 ° C / min, and then maintained at 275 ° C for 60 minutes. At the time of the calcination treatment, no pressure was applied and no pressure was applied. After the calcined metal bonding composition was taken out from the reflow furnace, it was peeled off from the glass slide to prepare a tensile test piece.

The tensile test was carried out using a universal tensile tester 5969 manufactured by Instron Co., Ltd. at a measurement speed of 0.72 mm/min. The tensile breaking stress and the elongation at break (strain) at the time of fracture of the test piece were measured. Further, the slope in the range of 0.05% to 0.25% in the obtained stress-strain curve (SS curve) was calculated from the approximate expression, and was set as Young's modulus.

(2) Method for producing metal bonded laminate and measurement of joint strength A metal joint composition (thickness: 90 μm) was used to bond a metal bonding composition to a silver-plated DBC substrate (area: 30 mm × 40 mm, cross-sectional structure: Cu Plate/SiN substrate/Cu plate = 0.2 mm thick / 0.32 mm thick / 0.2 mm thick) coated with 11 mm square. As pre-drying, the applied metal bonding composition was placed in an oven set at 70 ° C and dried for 30 minutes. A gold-sputtered Si wafer (bottom area: 5 mm × 5 mm or 10 mm × 10 mm) was laminated on the dried metal bonding composition, and pressed at 0.2 MPa. Further, the obtained laminated body was placed in a reflow furnace (manufactured by Shinapex Co., Ltd.) and subjected to calcination treatment. The calcination treatment in the reflow furnace was carried out under an atmospheric environment, and the temperature was raised 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. At the time of the calcination treatment, no pressure was applied and no pressure was applied. After the completion of the calcination treatment, a metal bonded laminate in which a gold-sputtered Si wafer was bonded to a silver-plated DBC substrate by a metal bonding material containing the sintered metal bonding composition was obtained.

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

(3) Measurement of Porosity The metal bonded laminate obtained in the above (2) was subjected to an ultrasonic flaw detector manufactured by Krautkramer, Japan (the frequency of the ultrasonic wave: 80 MHz, the probe Diameter: f3 mm, focal length PF = 10 mm). The reflection peak at the micro-adjustment to the joint interface was the highest, and the material sound velocity = Si: 9600 mm/s and Gain = 65 dB were measured. The threshold value of the reflection intensity was set to 55% and the above was regarded as the pore. The area of the pores obtained by binarizing the threshold value was calculated using the software, and the porosity was calculated. Further, as a test piece, a Si wafer having a laminated layer of 10 mm × 10 mm was used.

(4) Thermal cycle test The metal bonded laminate obtained in the above (2) was placed in a thermal shock tester (manufactured by Hutech) and kept at -40 ° C and 200 ° C for 10 minutes, respectively. The cycle was set to one cycle and taken out after 1000 cycles of implementation. After taking out, the porosity of the above (3) was measured, and the amount of increase in porosity with respect to 0 cycles (initial porosity) was calculated. Further, as a test piece, a Si wafer having a laminated layer of 10 mm × 10 mm was used.

(5) Printability The printability of the composition for metal bonding was printed by a manual printer using a plastic squeegee (manufactured by Toyo Technica Co., Ltd.) and a metal mask (manufactured by Murakami Co., Ltd.), and based on the following criteria. Conduct an evaluation. ○: Good △: Printable, but draws ×: High viscosity, not printable

(6) Application period The application period of the metal bonding composition was printed by a manual printer in the same manner as the evaluation of the printing property (5), and the evaluation was performed based on the following criteria. ○: It can be printed after being left for 5 hours in the released state. △: It can be printed after being left for 1 hour to 4 hours in the released state. ×: It is not printable after being left for 1 hour in the released state.

[Table 1]

As described in Table 1, the tensile fracture stress of the film at the time of firing at 275 ° C in any of the metal joining compositions of Examples 1 to 7 was 100 MPa or more, and the printability was good. And the application period is excellent. In any of the metal bonded laminates produced by using such a composition for metal bonding, it was confirmed that the measured values of the joint strength were 40 MPa of the upper limit of measurement, and the joint strength was 40 MPa or more. Further, the metal bonded laminate produced using the metal joining compositions of Examples 1 to 7 was subjected to a heat cycle test, and it was confirmed that the porosity after the test (= initial porosity + pore increase after thermal cycle) It is 40% or less and has high joint reliability.

On the other hand, in the metal joining composition of Comparative Example 1 and Comparative Example 2, the tensile breaking stress of the film when calcined at 275 ° C was less than 100 MPa, and the metal joining using Comparative Example 1 and Comparative Example 2 was used. The thermal cycle test was carried out on the metal bonded laminate produced of the composition, and as a result, the porosity was greatly increased after the test and exceeded 40%. The reason is considered to be that cracks occur due to the heat cycle test. In addition, the metal bonded laminate produced by using the metal bonding composition of Comparative Example 2 had a high porosity of 75% after the test and a low bonding strength of 31 MPa.

11‧‧‧Power semiconductor wafer

12‧‧‧Metal joints

13‧‧‧Copper-clad insulating substrate

13a‧‧‧Substrate

13b‧‧‧Cu layer

14‧‧‧heating materials

15‧‧‧ Heat sink

16‧‧‧Wire bonding wire

51, 53‧‧‧ slides

52‧‧‧Metal joint composition

54‧‧‧Test strips

(a) to (c) of FIG. 1 are flowcharts for explaining a method of producing a test piece for measurement of tensile fracture stress of a metal joining composition. 2 is a schematic plan view showing the shape and size (unit: mm) of a test piece for measuring the tensile fracture stress of the metal joining composition. 3 is a schematic cross-sectional view showing a configuration of a power device as an example of a metal bonded laminate.

Claims (7)

A composition for metal joining, which is a metal joining composition for joining a metal surface by calcination, wherein the metal joining composition contains silver particles and a dispersion medium, and the silver particles include particles Nanoparticles with a diameter of 1 nm to 99 nm, submicron particles with a particle size of 100 nm to 999 nm, and/or microparticles with a particle size of 1 μm to 999 μm, and tensile fracture of the film when calcined at 275 °C The stress is 100 MPa or more. The metal bonding composition according to claim 1, wherein the silver particles comprise the nanoparticles and the submicron particles. The metal bonding composition according to claim 2, wherein a mass ratio of the nanoparticle to the submicron particle is 4:6 to 7:3. A metal bonded laminate, which is a metal bonded laminate including a metal bonding material that bonds a first metal surface and a second metal surface, and is characterized in that: the metal bonding material is as in the first to the first A sintered body of the metal joining composition according to any one of the items of the present invention. 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 substrate or a plating layer containing Cu, Ag or Au. The metal bonded laminate according to claim 4, wherein the first metal face is a part of a semiconductor wafer, and the second metal face is a part of the substrate. An electrically controlled machine comprising the metal bonded laminate according to any one of claims 4 to 6.