JP2010053377A - Method for joining metallic member and method for producing metallic member-joined body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for firmly joining metallic members with the hot-sintered materials of metallic grains free from cracks, and to provide a method for producing a firmly joined metallic member-joined body. <P>SOLUTION: Disclosed are a method for joining metallic members and a method for producing metallic member-joined body wherein a paste-shaped metallic grain composition 2 composed of (A) hot sinterable metal grains with the average grain size of >0.1 to 50 μm and (B) a volatile dispersion medium is interposed between a plurality of metallic members 1, 3, heating is performed at 40 to 200°C in an inert gas, thus 10 to <100% of the volatile dispersion medium (B) in the composition is volatilized, thereafter, heating is performed at 70 to 400°C in an oxidizing gas or in a reducing gas, thus the volatile dispersion medium (B) remaining in the composition is perfectly volatilized, and the hot sinterable metallic grains (A) are sintered each other, so as to join a plurality of the metallic members. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for joining metal members using a paste-like metal particle composition comprising heat-sinterable metal particles and a volatile dispersion medium, and metal member joining using the paste-like metal particle composition. The present invention relates to a method for manufacturing a body.

A conductive / thermal conductive paste obtained by dispersing a metal powder such as silver, copper, or nickel in a liquid thermosetting resin composition is cured by heating to form a conductive / thermal conductive film. Therefore, formation of conductive circuits on printed circuit boards, formation of various electronic components such as resistors and capacitors, and electrodes of various display elements, formation of conductive films for electromagnetic wave shielding, capacitors, resistors, diodes, memories, arithmetic elements (CPU) and other chip components to substrates, formation of solar cell electrodes, especially formation of solar cell electrodes that cannot be processed at high temperatures due to the use of amorphous silicon semiconductors, multilayer ceramic capacitors, multilayer ceramic inductors It is used for forming external electrodes of chip-type ceramic electronic components such as multilayer ceramic actuators.

2. Description of the Related Art In recent years, chip components have increased in performance, and the amount of heat generated from the chip components has increased, and improvement in thermal conductivity as well as electrical conductivity is required. Therefore, it tries to improve electrical conductivity and thermal conductivity by increasing the content of metal particles as much as possible. However, when it does so, there exists a problem that the viscosity of a paste rises and workability | operativity falls remarkably.

In order to solve such a problem, the present inventors have developed a paste-like silver particle composition comprising silver powder and a volatile dispersion medium. When heated, the volatile dispersion medium is volatilized and the silver particles are sintered. Found that it was solid silver having extremely high electrical conductivity and thermal conductivity, and that it was useful for joining metal members and forming conductive circuits (WO2006 / 126614, WO2007 / 034833) . Further, a paste-like metal particle composition, for example, a paste-like silver particle composition is interposed between a plurality of metal members, and ultrasonic waves are applied by applying ultrasonic vibration while applying pressure by heating, or applying ultrasonic waves while applying and heating. The application of vibrations volatilized the volatile dispersion medium and found that when metal particles such as silver particles (A) were sintered together, it was found that a plurality of metal members could be firmly joined together, and an international application was filed (WO2008 / 062548 ).

However, when such a paste-like silver particle composition is interposed between a plurality of metal members and heated in an oxidizing gas containing oxygen gas such as air for sintering of the silver particles, the silver particles are sintered. Because of the rapidity, the curing is uneven in some places, and the volatilization of the volatile dispersion medium is not uniform in some places. As a result, the silver particles do not sinter uniformly, so cracks occur in the sintered solid silver. The present inventors have found that there is a problem that causes

WO2006 / 126614 WO2007 / 034833 WO2008 / 062548

As a result of intensive studies to solve the above problems, the present inventors have found that even when a paste-like metal particle composition is used as a bonding agent between a plurality of metal members, the metal particles are uniform without generating cracks. And a method of joining the metal particles sufficiently by sintering sufficiently. An object of the present invention is to join a metal member by joining the metal member by sintering the paste-like metal particle composition, and to firmly join the metal member without the crack of the sintered product of the metal particle. Another object of the present invention is to provide a method for manufacturing a metal member assembly.

This purpose is
“[1] A paste metal particle composition comprising (A) a heat-sinterable metal particle having an average particle diameter of greater than 0.1 μm and less than or equal to 50 μm and (B) a volatile dispersion medium, a plurality of metal members The amount of the volatile dispersion medium (B) in the paste-like metal particle composition is volatilized in an amount of 10 wt% to less than 100 wt% by heating at 40 ° C. or higher and 200 ° C. or lower in an inert gas. After that, the volatile dispersion medium (B) remaining in the paste-like metal particle composition is volatilized by heating at 70 ° C. or higher and 400 ° C. or lower in an oxidizing gas or a reducing gas, and heated and sintered. A method for joining metal members, comprising sintering the conductive metal particles (A) to join a plurality of the metal members.
[1-1] The method for producing a metal member assembly according to [1], wherein the volatile dispersion medium (B) has a volatilization amount of 20 wt% or more and 98 wt% or less.
[2] The heat-sinterable metal particles (A) are silver particles or copper particles produced by a reduction method, the volatile dispersion medium (B) is a hydrophilic solvent or an aliphatic hydrocarbon solvent, and is made of metal. The method for joining metal members according to [1], wherein the member is gold, silver, copper, palladium, platinum, or an alloy of these metals.
[3] The oxidizing gas is a mixed gas of oxygen gas of 0.1 volume% or more and 40 volume% or less and nitrogen gas of 99.9 volume% or less and 60 volume% or more, and the reducing gas is 1 volume% or more and 40 volume%. % Of hydrogen gas and 99% by volume or less and 60% by volume or more of nitrogen gas mixed gas according to [1], [1-1] or [2] .
[4] The bonded metal member has a shear bond strength of 5 MPa or more, and a volume resistivity of a sintered product of the heat-sinterable metal particles (A) is 1 × 10 ⁻¹ Ω · cm. The method for joining metal members according to [1], [1-1], [2] or [3], characterized in that:
Is achieved.

This purpose is further
“[5] A paste metal particle composition comprising (A) a heat-sinterable metal particle having an average particle diameter of greater than 0.1 μm and less than or equal to 50 μm and (B) a volatile dispersion medium. The amount of the volatile dispersion medium (B) in the paste-like metal particle composition is volatilized in an amount of 10 wt% to less than 100 wt% by heating at 40 ° C. or higher and 200 ° C. or lower in an inert gas. After that, the volatile dispersion medium (B) remaining in the paste-like metal particle composition is volatilized by heating at 70 ° C. or higher and 400 ° C. or lower in an oxidizing gas or a reducing gas, and heated and sintered. A method for producing a metal member assembly comprising sintering the conductive metal particles (A) to join a plurality of the metal members.
[5-1] The method for producing a metal member assembly according to [5], wherein the volatile dispersion medium (B) has a volatilization amount of 20 wt% or more and 98 wt% or less.
[6] The heat-sinterable metal particles (A) are silver particles or copper particles produced by a reduction method, the volatile dispersion medium (B) is a hydrophilic solvent or an aliphatic hydrocarbon solvent, and is made of metal. The method for producing a metal member assembly according to [5] or [5-1], wherein the member is gold, silver, copper, palladium, platinum, or an alloy of each of these metals.
[7] The oxidizing gas is a mixed gas of oxygen gas of 0.1 volume% or more and 40 volume% or less and nitrogen gas of 99.9 volume% or less and 60 volume% or more, and the reducing gas is 1 volume% or more and 40 volume%. % Of hydrogen gas and 99% by volume or less and 60% by volume or more of nitrogen gas mixed gas, wherein the metal member assembly according to [5], [5-1] or [6] Production method.
[8] The shear bonding strength of the metal member assembly is 5 MPa or more, and the volume resistivity of the sintered product of the heat-sinterable metal particles (A) is 1 × 10 ⁻¹ Ω · cm or less. The method for producing a metal member assembly according to [5], [5-1], [6] or [7], wherein
[9] The method for producing a metal member assembly according to [5], [6] or [7], wherein the metal member is a metal substrate or an electronic component having a metal part. Is achieved.

According to the joining method of the present invention, in joining between metal members, the volatile dispersion medium (B) in the composition is volatilized by heating the paste-like metal particle composition, and the heat-sinterable metal particles (A) are bonded together. When sintered into a solid state, since the sintered product becomes a dense sintered product without causing cracks, the metal member can be firmly joined. In addition, even when joining metal members that are easily oxidized and corroded or discolored, the volatile dispersion medium in the composition is volatilized by heating the paste-like metal particle composition, and the heat-sinterable metal particles When (A) is sintered and becomes a solid state, the sintered product can be firmly bonded without causing cracks and without causing corrosion or discoloration of the metal member.

According to the method for producing a metal member assembly of the present invention, the volatile dispersion medium (B) in the composition is volatilized by heating the paste-like metal particle composition, and the heat-sinterable metal particles (A) are sintered together. Since it becomes a dense sintered product without causing cracks in the sintered product when it is solidified, it is possible to manufacture a metal member assembly that is firmly bonded. In addition, even when joining metal members that are easily oxidized and corroded or discolored, the volatile dispersion medium in the composition is volatilized by heating the paste-like metal particle composition, and the heat-sinterable metal particles (A) When sintered together to form a solid state, the sintered product is not cracked, and the metal member is not corroded or discolored. can do.

The metal member joining method of the present invention is a paste-like metal particle composition comprising (A) heat-sinterable metal particles having an average particle size of greater than 0.1 μm and 50 μm or less, and (B) a volatile dispersion medium. Is interposed between a plurality of metal members and heated in an inert gas at a temperature of 40 ° C. or higher and 200 ° C. or lower by 10% or more by weight of the volatile dispersion medium (B) contained in the composition. After volatilizing the amount less than 100% by weight, the volatile dispersion medium (B) remaining in the composition is volatilized by heating at 70 ° C. or higher and 400 ° C. or lower in an oxidizing gas or a reducing gas. The heat-sinterable metal particles (A) are sintered to join together a plurality of metal members.

The average particle size of the heat-sinterable metal particles (A) is larger than 0.1 μm and not larger than 50 μm. This average particle diameter is an average particle diameter of primary particles obtained by a laser diffraction / scattering particle size distribution measurement method. When the average particle diameter exceeds 50 μm, the sinterability of the heat-sinterable metal particles is lowered, so that the average particle diameter is preferably small. For this reason, it is preferable that it is 20 micrometers or less, and it is especially preferable that it is 10 micrometers or less. However, if the average particle size is 0.1 μm or less, the surface activity is too strong, the storage stability of the paste-like metal particle composition is lowered, and the bonding strength at the time of heat sintering becomes non-uniform. The diameter is greater than 0.1 μm. From this viewpoint, the average particle size is preferably 0.2 μm or more. That is, the average particle size range of the heat-sinterable metal particles (A) is preferably 0.2 to 10 μm.

The material of the heat-sinterable metal particles is solid at room temperature, and only needs to be easily sintered by heating. Gold, silver, copper, palladium, nickel, tin, aluminum, and alloys of these metals are exemplified. Furthermore, a metal compound is illustrated.
Among these materials, silver, a silver alloy, copper, and a copper alloy are preferable, and silver or copper is particularly preferable in terms of heat-sinterability, thermal conductivity of the sintered product, and conductivity. The silver particles may have a part of the surface or inside thereof that may be silver oxide or silver peroxide, and the entire surface may be silver oxide or silver peroxide. The copper particles may have copper oxide on the surface or part of the inside, or the entire surface may be copper oxide.

The heat-sinterable metal particles are usually made of a single material, but may be a mixture of particles made of a plurality of materials.
Heat-sinterable metal particles are made of metal (for example, copper, nickel, or aluminum) particles whose surfaces are plated with the heat-sinterable metal (for example, silver), and the surface is made of the heat-sinterable metal (for example, silver). Plated resin (for example, epoxy resin, polyethersulfone resin) particles may be used.

The shape of the heat-sinterable metal particles is not particularly limited, and examples thereof include a spherical shape, an elliptical spherical shape, a spindle shape, a granular shape, a substantially cubic shape, a flake shape, and an indefinite shape. The shape is preferably spherical, granular, spherical or flaky from the viewpoint of storage stability. Preferred heat-sinterable metal particles are silver particles made by the reduction method and copper particles made by the reduction method.
Many methods for producing silver particles by the reduction method have been proposed. Usually, an aqueous solution of a reducing agent such as formalin is added to an aqueous solution of silver nitrate by adding an aqueous solution of sodium hydroxide to an aqueous solution of silver nitrate. It is produced by reducing silver to form a silver particle dispersion, filtering the dispersion, washing the filtration residue with water, and drying. In addition, copper particles obtained by the reduction method are usually prepared by contact-reacting a copper sulfate aqueous solution and a hydrazine aqueous solution to reduce and precipitate copper powder, washing with pure water, and drying (see, for example, JP-A-59-59). 11630).

In the heat-sinterable metal particles (A), the surface of the heat-sinterable metal particles may be coated or treated with an organic substance. In particular, when the organic substance is a water-repellent organic substance, the lubricity is excellent, so that the dispersibility in the paste-like metal particle composition of the present invention is excellent, which is preferable. Examples of such water-repellent organic substances include high / intermediate fatty acids, high / intermediate fatty acid metal salts (excluding alkali metal salts), high / intermediate fatty acid amides, high / intermediate fatty acid amines, and high / intermediate fatty acid esters. . High and intermediate fatty acids are particularly preferred in terms of coating effect and treatment effect.

A higher fatty acid is a fatty acid having 15 or more carbon atoms, such as pentadecanoic acid, hexadecanoic acid (palmitic acid), heptadecanoic acid, octadecanoic acid (stearic acid), 12-hydroxyoctadecanoic acid (12-hydroxystearic acid), eicosanoic acid ( Linear saturated fatty acids such as arachidic acid), docosanoic acid (behenic acid), tetracosanoic acid (lignoceric acid), hexacosanoic acid (serotic acid), octacosanoic acid (montanic acid); 2-pentylnonanoic acid, 2-hexyldecanoic acid, 2- Examples include branched saturated fatty acids such as heptyldodecanoic acid and isostearic acid; unsaturated fatty acids such as palmitoleic acid, oleic acid, isooleic acid, elaidic acid, linoleic acid, linolenic acid, ricinoleic acid, gadrenic acid, erucic acid, and ceracoleic acid The

Intermediate fatty acids are fatty acids having 6 to 14 carbon atoms, such as hexanoic acid (caproic acid), heptanoic acid, octanoic acid (caprylic acid), nonanoic acid (pelargonic acid), decanoic acid (capric acid), undecanoic acid, Linear saturated fatty acids such as dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid); isohexanoic acid, isoheptanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, 2-propylheptanoic acid, isodecanoic acid, Illustrative examples include branched saturated fatty acids such as isoundecanoic acid, 2-butyloctanoic acid, isododecanoic acid and isotridecanoic acid; and unsaturated fatty acids such as 10-undecenoic acid.

The coating amount of the organic matter varies depending on the particle size, specific surface area, shape, etc. of the metal particles, but is preferably 0.01 to 3% by weight, more preferably 0.1 to 2% by weight of the heat-sinterable metal particles (A). preferable. If the amount is too small, the heat-sinterable metal particles (A) tend to agglomerate and the storage stability is lowered.As a result, the bonding strength at the time of heat-sintering becomes non-uniform. This is because the heat sinterability of) decreases.

The amount of organic matter attached can be measured by an ordinary method. For example, a method of measuring weight loss by heating an organic substance to a high temperature (for example, higher than the boiling point) in nitrogen gas, or heating sinterable metal particles (A) by heating them in an oxygen stream. ), Carbon in the organic matter adhering to the carbon dioxide is changed to carbon dioxide, and quantitative analysis is performed by infrared absorption spectroscopy.

The flaky heat-sinterable metal particles to which organic substances are attached can be produced, for example, by putting spherical metal particles and organic substances into a ball mill and striking the metal particles with a ball (special features). No. 40-6971 and JP-A 2000-234107 [0004]).
Specifically, granular heat-sinterable metal particles, high / intermediate fatty acids, high / intermediate fatty acid metal salts (except alkali metal salts), high / intermediate fatty acid esters, high / intermediate fatty acid amides, The medium fatty acid amine organic substance and the like are put into a rotary drum device (for example, a ball mill) together with a ceramic ball, and the metal particles are beaten with the ball, whereby the flaky heat-sinterable metal particles to which the organic substance is adhered are obtained. Can be manufactured. At this time, organic substances such as high / intermediate fatty acids, high / intermediate fatty acid metal salts (except alkali metal salts), high / intermediate fatty acid esters, high / intermediate fatty acid amides, high / intermediate fatty acid amines, etc. It adheres to the surface of the conductive metal particles.

The surface of the heat-sinterable metal particles (A) may be covered with more than half of such high / intermediate fatty acid, but it is preferable that the surface is covered entirely. Thus, when the surface of the metal particles is coated with a water-repellent organic material, the heat-sinterable metal particles (A) exhibit water repellency.
The heat-sinterable metal particles (A) whose surfaces are coated with an organic material can also be produced by immersing the heat-sinterable metal particles in an organic material solution and then taking out and drying the metal particles.

The volatile dispersion medium (B) is blended in order to make powdery metal particles into a paste. The paste form includes a cream form and a slurry form. In order to make the heat-sinterable metal particles sinterable during heating, or to make the paste-like metal particle composition usable as a bonding agent by heating, it must be volatile rather than non-volatile. is necessary. In particular, when the heat-sinterable metal particles (A) are silver particles or copper particles, if the dispersion medium is volatilized during sintering, the silver particles and copper particles are easily sintered and can be easily used as a bonding agent. Because. The boiling point of the volatile dispersion medium is preferably 60 ° C to 300 ° C. When the boiling point is less than 60 ° C., the solvent easily evaporates during the preparation of the paste-like metal particle composition, and when the boiling point is higher than 300 ° C., the volatile dispersion medium (B) remains even after heating. Because it might be.

Such a volatile dispersion medium (B) is composed of a volatile hydrocarbon compound composed of carbon atoms and hydrogen atoms, a volatile organic compound composed of carbon atoms, hydrogen atoms and oxygen atoms, carbon atoms, hydrogen atoms and nitrogen atoms. It is selected from volatile organic compounds, volatile organic compounds composed of carbon atoms, hydrogen atoms, oxygen atoms and nitrogen atoms, a mixture of hydrophilic volatile organic compounds of the volatile organic compounds and water, and the like. These are all liquid at room temperature.
The water is preferably pure water, and its electric conductivity is preferably 100 μS / cm or less, more preferably 10 μS / cm or less. The pure water production method may be a normal method, and examples include an ion exchange method, a reverse osmosis method, and a distillation method.

Specifically, as volatile organic compounds composed of carbon atoms, hydrogen atoms and oxygen atoms, volatilization of ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, etc. Monohydric alcohol: ethylene glycol monomethyl ether (methyl cellosolve, methyl carbitol), ethylene glycol monoethyl ether (emethyl cellosolve, ethyl carbitol), ethylene glycol monopropyl ether (propyl cellosolve, propyl carbitol), ethylene glycol mono Ethers such as butyl ether (butyl cellosolve, butyl carbitol), propylene glycol monomethyl ether, methylmethoxybutanol Volatile monohydric alcohols having binding; benzyl alcohol, volatile aralkyl alcohols such as 2-phenylethyl alcohol, ethylene glycol, propylene glycol, volatile polyhydric aliphatic alcohols such as glycerin are exemplified.

Furthermore, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol (4-hydroxy-4-methyl-2-pentanone), 2-octanone, isophorone (3,5,5-trimethyl-2-cyclohexene-1- ON), volatile aliphatic ketones such as dibutylketone (2,6-dimethyl-4-heptanone); ethyl acetate (ethyl acetate), butyl acetate, acetoxyethane, methyl butyrate, methyl hexanoate, methyl octoate, decane Volatile aliphatic carboxylic acid esters such as methyl acid, methyl cellosolve acetate, propylene glycol monomethyl ether acetate; tetrahydrofuran, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene Glycol dibutyl ether, propylene glycol dimethyl ether, volatile aliphatic ethers such as ethoxyethyl ether, and the like.

Examples of volatile hydrocarbon compounds composed of carbon atoms and hydrogen atoms include volatile aliphatic hydrocarbons such as n-paraffin and isoparaffin; and volatile aromatic hydrocarbons such as toluene and xylene.

Examples of volatile organic compounds composed of carbon atoms, hydrogen atoms and nitrogen atoms include volatile alkyl nitriles such as acetonitrile and propionitrile.
Examples of volatile organic compounds composed of carbon atoms, hydrogen atoms, oxygen atoms and nitrogen atoms include volatile carboxylic acid amides such as acetamide and N, N-dimethylformamide. Other examples include low molecular weight volatile silicone oils and volatile organic modified silicone oils.

The blending amount of the volatile dispersion medium (B) is an amount sufficient to make the heat-sinterable metal particles (A) into a paste at room temperature. Depending on the particle size, surface area, shape, etc. of the heat-sinterable metal particles (A), and the type, viscosity, etc. of the volatile dispersion medium (B), the amount sufficient to make a paste varies, but the specific For example, it is 3 to 30 parts by weight per 100 parts by weight of the heat-sinterable metal particles (A).
The paste-like metal particle composition used in the method for joining metal members of the present invention includes non-metallic powders other than the heat-sinterable metal particles (A), metal compounds, unless the object of the present invention is contrary to Additives such as metal complexes, thixotropic agents, stabilizers, colorants and the like may be incorporated in small or trace amounts.

The paste-like metal particle composition used in the method for joining metallic members of the present invention comprises (A) heat-sinterable metal particles having an average particle size of greater than 0.1 μm and not more than 50 μm, and (B) volatile dispersion. The medium can be easily produced by adding it to a mixer and stirring and mixing it until it becomes a uniform paste.

The paste-like metal particle composition used in the method for joining metal members of the present invention is a mixture of heat-sinterable metal particles (A) and a volatile dispersion medium (B) and is paste-like at room temperature. The paste form includes a cream form and a slurry form. By making it into a paste, it can be discharged in a thin line from a cylinder or nozzle, and printing with a metal mask is easy. The thickness of the paste-like metal particle composition interposed between a plurality of metal members is not particularly limited as long as the necessary bonding strength is exhibited by heat sintering of the heat sinterable metal particles (A). . Usually, it is 5 μm or more and 1200 μm or less.

In the metal member used in the method for joining metal members of the present invention, the applied paste-like metal particle composition volatilizes the volatile dispersion medium in the composition by heating, and the heat-sinterable metal particles ( A) is an object to be joined by sintering. Examples of the material of the metal member include gold, silver, copper, platinum, palladium, nickel, tin, aluminum, and alloys of these metals. Among these, copper, silver, gold, platinum, palladium, or an alloy of these metals is preferable in terms of conductivity and bondability. The metal member may be plated with the metal. Examples of the metal member include a lead frame, a printed circuit board, a semiconductor chip, and a heat sink, all or part of which is made of metal.

The metal member joining method of the present invention comprises the paste-like metal particle composition interposed between a plurality of metal members and heated in an inert gas at 40 ° C. or more and 200 ° C. or less. After volatilizing an amount of 10% by weight or more and less than 100% by weight of the volatile dispersion medium (B) contained in the particle composition, it is 70 ° C. or more and 400 ° C. in an active gas such as an oxidizing gas or a reducing gas. The volatile dispersion medium (B) remaining in the paste-like metal particle composition is volatilized by heating at a temperature of ℃ or less, and the heat-sinterable metal particles (A) are sintered together to form a plurality of metal members. It is the method of joining. At this time, the type of heat-sinterable metal particles (A) and the type of active gas are not particularly limited, but when the heat-sinterable metal particles (A) are silver particles, it is preferably an oxidizing gas, When the sinterable metal particles (A) are copper particles, it is preferably a reducing gas.

Even when the paste-like metal particle composition is heated in an inert gas, the sinterability of the heat-sinterable metal particles (A) is poor. On the other hand, when the paste-like metal particle composition is heated in an oxidizing gas or a reducing gas, the heat-sinterable metal particles (A) sinter in a short time because they have excellent sinterability. In the state of being interposed between metal members, the method of applying heat is not uniform, so uneven sinterability is likely to occur, and similarly, the volatilization of the volatile dispersion medium (B) is not uniform, so that the heat-sinterable metal particles ( A) is difficult to sinter uniformly, and as a result, cracks are likely to occur in the sintered product of the heat-sinterable metal particles (A).

The metal member joining method of the present invention is such that the heat-sinterable metal particles (A) in the paste-like metal particle composition as described above have poor sinterability when heated in an inert gas, and are oxidizable. By utilizing the property of excellent sinterability when heated in a gas or reducing gas, a sintered product of heat-sinterable metal particles (A) free from cracks is obtained. That is, before the heat-sinterable metal particles (A) are sintered, by heating at a temperature of 40 ° C. or higher and 200 ° C. or lower, the volatile dispersion medium in the paste-like metal particle composition that causes cracking ( The amount of B) is reduced. Specifically, an amount of 10% or more and less than 100% by weight of the volatile dispersion medium (B) is volatilized by this heating.

When the heating temperature is less than 40 ° C., the volatile dispersion medium (B) hardly volatilizes. When the heating temperature exceeds 200 ° C., the heat-sinterable metal particles (A) start to sinter unevenly. Cracks are likely to occur. If the volatilization amount of the volatile dispersion medium (B) is less than 10%, the heating effect is not obtained, so the volatilization amount is 10% or more, but preferably 20% by weight or more.
On the other hand, when 100% of the volatile dispersion medium (B) is volatilized, the paste-like metal particle composition is easily removed from the metal member by vibration, so the volatilization amount is less than 100%, but preferably 98% or less.

In the method for joining metal members of the present invention, an amount of 10% or more and less than 100% by weight of the volatile dispersion medium (B) that causes non-uniform sintering of the heat-sinterable metal particles (A) is volatilized. After that, the heat-sinterable metal particles (A) are heated in an oxidizing gas or a reducing gas, so that the heat-sinterable metal particles (A) can be uniformly sintered. A small amount of sintered product can be obtained.

At this time, when the heat-sinterable metal particles (A) are copper particles, there is a problem in that when heated in an oxidizing gas, the copper particles are oxidized and the conductivity of the sintered product is lowered. It is preferable to heat with. When copper is heated in a reducing gas, there is no problem of corrosion or discoloration due to oxidation of the metal member, and it is sufficiently sintered and has excellent bonding strength. Further, since copper oxide is reduced to copper when heated in a reducing gas, there is no problem of corrosion or discoloration due to oxidation of the metal member, and it is sufficiently sintered and excellent in conductivity.

For the same reason, when the metal member is copper, it is preferable to heat in a reducing gas regardless of the material of the heat-sinterable metal particles (A).

The heat-sinterable metal particles (A) in the paste-like metal particle composition used for joining and the surface metal of the metal member may be the same metal or a metal alloy, or a metal that easily forms an alloy. It may be between each other.

In the metal member joining method of the present invention, examples of the inert gas for volatilizing the volatile dispersion medium (B) include helium gas, argon gas, and nitrogen gas, with nitrogen gas being preferred. Moreover, it is preferable that the purity of these inert gas is 99.99 volume% or more.

The oxidizing gas preferably contains oxygen gas. Examples of components other than oxygen gas include helium gas, argon gas, and inert gas such as nitrogen gas, but nitrogen gas is preferable from the viewpoint of economy. The ratio of the oxygen gas and the inert gas is not limited, but it is preferable that the oxygen gas is 0.1 to 40% by volume and the remainder is the inert gas. The oxidizing gas may be air.

The reducing gas need not be a pure product, and may be a mixture with an inert gas. Examples of the reducing gas include hydrogen gas, carbon monoxide, and ammonia decomposition gas, but hydrogen gas is preferable. The ratio of the reducing gas component to the inert gas component in the reducing gas is not limited, but when the reducing gas component is hydrogen gas, it is 1 to 40% by volume, and the remainder is more preferably an inert gas. . When the ratio of hydrogen gas is less than 1% by volume, the effect of reducing oxides on the surface of easily oxidized metal members such as copper and copper alloys is poor, and heat sintering in the paste-like metal particle composition This is because if the heat-sinterability of the flammable metal particles (A) is not sufficient and the bonding strength is reduced and the hydrogen gas ratio exceeds 40% by volume, the danger of handling as flammable gas increases. Most preferably, the reducing gas is a reducing gas called a forming gas composed of 5 to 25% by volume of hydrogen gas and 95 to 75% by volume of nitrogen gas.

The reducing gas preferably does not contain oxygen gas, but even if it is contained, the reducing gas is preferably as small as possible to prevent oxidation and danger of the metal member, and particularly preferably 100 ppm or less. By heating the paste-like metal particle composition between metal members in such a reducing gas, the metal member does not corrode or discolor due to oxidation, and the paste-like metal particle composition is heated and fired in the paste-like metal particle composition. The cohesive metal particles (A) can be sufficiently sintered to firmly join the metal members.

The paste-like metal particle composition used in the present invention volatilizes the volatile dispersion medium by heating. At this time, since the paste-like metal particle composition has low sinterability of the heat-sinterable metal particles (A) in an inert gas atmosphere, the volatile dispersion medium can be volatilized while suppressing sintering. After that, by heating to a temperature equal to or higher than the sintering temperature of the heat-sinterable metal particles (A) in an oxidizing gas or a reducing gas, the remaining volatile dispersion medium (B) is volatilized, The metal particles (A) are sintered to form a solid metal having excellent conductivity without cracks, and the metal members are strongly bonded to each other. The shear bond strength of the joined body is preferably 5 MPa or more. The volume resistivity of the sintered product is preferably 1 × 10 ⁻¹ Ω · cm or less. Note that pressure or ultrasonic vibration may be applied to the paste-like metal particle composition during heating in an oxidizing gas or a reducing gas.

When heated in an oxidizing gas or a reducing gas, the remaining volatile dispersion medium (B) is volatilized, and then the heat-sinterable metal particles (A) may be sintered together and remain. The heat-sinterable metal particles (A) may be sintered together with the volatilization of the volatile dispersion medium (B). In particular, when the heat-sinterable metal particles (A) are silver particles or copper particles, the silver or copper inherently has high strength and extremely high electrical and thermal conductivity, so the silver particles or copper particles are sintered together. Objects also have great strength and very high electrical and thermal conductivity.

The heating temperature in the oxidizing gas or the reducing gas may be any temperature as long as the remaining volatile dispersion medium (B) can be volatilized and the heat-sinterable metal particles (A) can be sintered. It is more than 150 degreeC, and 150 degreeC or more is more preferable. However, if the temperature exceeds 400 ° C., the remaining volatile dispersion medium may suddenly evaporate, and the shape of the solid metal may be adversely affected. Preferably it is 300 degrees C or less.

In the paste-like metal particle composition used in the present invention, the volatile dispersion medium (B) is volatilized by heating, and the heat-sinterable metal particles (A) are sintered together. When used for bonding between metal members, it adheres firmly to metal members that have been in contact, such as gold-plated substrates, silver substrates, silver-plated metal substrates, copper substrates, etc. Since it adheres firmly to a metal part such as an electrode on a substrate, the metal member joining method of the present invention is useful for joining a metal-based substrate or an electronic component, electronic device, electric component, electric device or the like having a metal portion. is there.

Such bonding includes bonding of chip parts such as capacitors and resistors and circuit boards, bonding of semiconductor chips such as diodes, memories, ICs, and CPUs to lead frames or circuit boards, and high-heat generation CPU chips and cooling plates. Are exemplified.

The method for producing a metal member assembly according to the present invention comprises: (A) heat-sinterable metal particles having an average particle size of greater than 0.1 μm and 50 μm or less; and (B) paste-like metal particles comprising a volatile dispersion medium. 10% by weight of the volatile dispersion medium (B) in the paste-like metal particle composition by interposing the composition between a plurality of metal members and heating in an inert gas at 40 ° C. or higher and 200 ° C. or lower. After volatilizing the amount less than 100% by weight, the volatile dispersion medium remaining in the paste-like metal particle composition by heating at 70 ° C. or more and 400 ° C. or less in an oxidizing gas or a reducing gas ( B) is volatilized, the heat-sinterable metal particles (A) are sintered together, and a plurality of the metal members are joined together.

Metal member, heat-sinterable metal particles (A) having an average particle size greater than 0.1 μm and 50 μm or less, volatile dispersion medium (B), volatilization conditions of volatile dispersion medium (B), inert gas, The oxidizing gas, reducing gas, heat sintering conditions, and the like are as described for the method for joining metal members. The thickness of the heat-sintered metal layer interposed between the plurality of metal members is not particularly limited as long as the necessary bonding strength is exhibited. Usually, it is 3 μm or more and 1000 μm or less. The joined body of metal members thus obtained has a high joining strength. The shear bond strength is preferably 5 MPa or more, and the volume resistivity of the sintered product is preferably 1 × 10 ⁻¹ Ω · cm or less.

As such a metal member joined body, a joined body of a chip component such as a capacitor or a resistor and a circuit board, a joined body of a semiconductor chip such as a diode, memory, IC, or CPU and a lead frame or a circuit board, a high heat generating body A joined body of a CPU chip and a cooling plate is exemplified.

Examples and comparative examples of the present invention will be given. In the examples and comparative examples, “parts” means “parts by weight”. Volatile amount of volatile dispersion medium in paste-like metal particle composition, shear adhesive strength of metal member, volume resistivity of sintered product of heat-sinterable metal particles, in sintered product of heat-sinterable metal particles The number of cracks, the oxidation of copper as a metal member after joining, and the oxygen gas concentration in the atmosphere gas were measured and evaluated as follows. In addition, the temperature in case there is no description in particular is 23 degreeC.

[Volatilization amount of volatile dispersion medium]
100 μm thick having four openings (2.5 mm × 2.5 mm) at intervals of 10 mm on a silver substrate or copper substrate (made of oxygen-free copper) having a width of 25 mm × length of 70 mm and a thickness of 1.0 mm The paste-like metal particle composition was printed and applied using a metal mask, and a silver chip or a copper chip (made of oxygen-free copper) having a size of 2.5 mm × 2.5 mm × 0.5 mm was mounted thereon. The silver substrate or copper substrate on which this silver chip or copper chip is mounted is placed in a gas circulation furnace at room temperature, the atmosphere is replaced with the gas used in the examples, and the temperature rising rate is 1 ° C. from normal temperature while flowing at a flow rate of 1 liter / min. The temperature was raised to 80 ° C./sec, and after maintaining the predetermined time in the examples at 80 ° C., the mixture was cooled to room temperature to reduce the amount of volatile dispersion medium in the paste-like metal particle composition. At this time, from the net weight of the paste-like metal particle composition after heating to the net weight of the paste-like metal particle composition before heating, the weight ratio of the volatile dispersion medium volatilized by heating was calculated by the following formula.

Volatile amount of volatile dispersion medium (%) = (ST) × 100 / (S × U)
S = Net amount of paste-like metal particle composition before heating (g)
T = Net amount of paste-like metal particle composition after heating (g)
U = content of volatile dispersion medium in paste-like metal particle composition before heating = volatile dispersion medium weight / (heat-sinterable metal particle weight + volatile dispersion medium weight)

[Shear bond strength of metal parts]
100 μm thick having four openings (2.5 mm × 2.5 mm) at intervals of 10 mm on a silver substrate or copper substrate (made of oxygen-free copper) having a width of 25 mm × length of 70 mm and a thickness of 1.0 mm The paste-like metal particle composition was printed and applied using a metal mask. A silver chip or a copper chip (made of oxygen-free copper) having a size of 2.5 mm × 2.5 mm × 0.5 mm was mounted on the paste-like metal particle composition applied by printing. The silver substrate or copper substrate on which this silver chip or copper chip is mounted is placed in a gas circulation furnace at room temperature, the atmosphere is replaced with the gas used in the examples, and the temperature rising rate is 1 ° C. from normal temperature while flowing at a flow rate of 1 liter / min. The temperature was raised to 80 ° C./sec, and after maintaining the predetermined time in the examples at 80 ° C., the mixture was cooled to room temperature to reduce the amount of volatile dispersion medium in the paste-like metal particle composition.

Next, after replacing the atmosphere with the gas used in the examples, the temperature was raised from room temperature to 250 ° C. at a heating rate of 1 ° C./second while flowing at a flow rate of 1 liter / minute, held at 250 ° C. for 1 hour, and then to room temperature. Cooled down. The remaining volatile dispersion medium is completely volatilized, and the heat-sinterable metal particles in the paste-like metal particle composition are sintered to form a silver substrate or a copper substrate (made of oxygen-free copper) and a silver chip or A joined body of copper chips (made of oxygen-free copper) was formed. The thickness of the sintered product between the heat-sinterable metal particles was about 70 to 80 μm.

The bonded body thus obtained, that is, the test body was set on a test body mounting tool of an adhesive strength tester, and the side surface of the silver chip or copper chip was pressed by a pressing bar of the adhesive strength tester at a thickness rate of 23 mm / min. And the load at the time when the joint portion was sheared and broken was defined as the shear bond strength (unit: MPa).

[Volume resistivity of sintered product]
A paste-like metal particle composition is applied on a polytetrafluoroethylene resin plate having a width of 50 mm, a length of 50 mm, and a thickness of 1.0 mm using a metal mask having a thickness of 10 mm and a length of 10 mm and a thickness of 10 μm. did. After replacing the atmosphere with the gas used in the example, the temperature was increased from room temperature to 80 ° C. at a rate of temperature increase of 1 ° C./second while flowing at a flow rate of 1 liter / min, and after maintaining the predetermined time in the example at 80 ° C., After cooling to room temperature, the heat-sinterable metal particles of the paste-like metal particle composition were sintered.

Subsequently, in order to completely volatilize the remaining volatile dispersion medium and sinter the heat-sinterable metal particles in the paste-like metal particle composition, the atmosphere is replaced with the gas used in the examples, and then the flow rate is 1 liter. The temperature was raised from room temperature to 250 ° C. at a rate of temperature rise of 1 ° C./second while flowing at a rate of 1 minute, and kept at 250 ° C. for 1 hour, and then cooled to room temperature.
The plate-like copper thus obtained was measured for volume resistivity (unit: Ω · cm) by a method according to JIS K 7194.

[Number of cracks in sintered product]
The sintered product of the joint part of the specimen for measuring the shear bond strength of the metal member was observed with an X-ray transmission imaging apparatus (model number SJV-2000, output 60 kV) manufactured by Softex Co., Ltd., and cracks in the sintered body were observed. And the number of cracks with a length of 0.1 mm or more per 2.5 mm × 2.5 mm was measured.

[Oxidation of copper]
By visual observation, the copper substrate of the test body for measuring the shear bond strength of the metal member was compared with the copper substrate for preparing the test body, and the change in color was evaluated.

[Concentration of oxygen gas in atmospheric gas]
The oxygen gas concentration in the atmosphere during the heating and sintering was measured with an oxygen concentration meter (KF-400, manufactured by Toray Engineering Co., Ltd.).

[Example 1]
Volatile in 100 parts of commercially available silver particles produced by the reduction method and coated with stearic acid on the surface (shape: granular, average particle size of primary particles: 1.1 μm, amount of stearic acid: 0.3 wt%) 8 parts of 2- (2-butoxyethoxy) ethyl acetate (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) is added as an aqueous dispersion medium, and a paste-like silver particle composition is prepared by uniformly mixing with a spatula did.

In order to volatilize the volatile dispersion medium 2- (2-butoxyethoxy) ethyl acetate in this paste-like silver particle composition, it is 20 minutes at 80 ° C. in nitrogen gas (purity 99.99%) as an inert gas. It heated and measured the volatilization amount of the volatile dispersion medium at this time. Next, the remaining volatile dispersion medium is completely volatilized by heating in air, which is an oxidizing gas, and the silver particles are sintered, so that a specimen for measuring shear bond strength and volume resistivity measurement are obtained. A test specimen was prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 1. From the above results, it was found that this joining method is useful for strongly joining metal members without cracks in the sintered silver particles in the paste-like silver particle composition.

[Example 2]
Volatile in 100 parts of commercially available silver particles produced by the reduction method and coated with stearic acid on the surface (shape: granular, average particle size of primary particles: 1.1 μm, amount of stearic acid: 0.3 wt%) By adding 8 parts of an isoparaffin (trade name Isosol 400, manufactured by Nippon Petrochemical Co., Ltd.), an aliphatic hydrocarbon having a distillation range of 210 ° C. to 260 ° C., and mixing uniformly using a spatula A pasty silver particle composition was prepared.

In order to volatilize the isoparaffin which is a volatile dispersion medium for this paste-like silver particle composition, it is heated at 80 ° C. for 20 minutes in nitrogen gas (purity 99.99%) as an inert gas, and the volatile dispersion at this time The volatilization amount of the medium was measured. Next, the remaining volatile dispersion medium is completely volatilized by heating in a mixed gas of 10% by volume of hydrogen gas, which is a reducing gas, and 90% by volume of nitrogen gas, and the silver particles are sintered. A test specimen for measuring adhesive strength and a test specimen for measuring volume resistivity were prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 1. From the above results, it was found that this joining method is useful for strongly joining metal members without cracks in the sintered silver particles in the paste-like silver particle composition.

[Example 3]
In Example 1, in order to volatilize 2- (2-butoxyethoxy) ethyl acetate, which is a volatile dispersion medium in the paste-like silver particle composition, in nitrogen gas (purity 99.99%), which is an inert gas. The mixture was heated at 80 ° C. for 40 minutes, and the volatilization amount of the volatile dispersion medium at this time was measured. Next, the remaining volatile dispersion medium is completely volatilized by heating in air, which is an oxidizing gas, and the silver particles are sintered, so that a specimen for measuring shear bond strength and volume resistivity measurement are obtained. A test specimen was prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 1. From the above results, it was found that this joining method is useful for strongly joining metal members without cracks in the sintered silver particles in the paste-like silver particle composition.

[Example 4]
Volatilized in 100 parts of commercially available copper particles produced by the reduction method and coated on the surface with stearic acid (shape: granular, average particle size of primary particles: 1.0 μm, amount of stearic acid: 0.7% by weight) 10 parts of 2- (2-butoxyethoxy) ethyl acetate (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) is added as a conductive dispersion medium, and a paste-like copper particle composition is prepared by uniformly mixing with a spatula did.

In order to volatilize the volatile dispersion medium 2- (2-butoxyethoxy) ethyl acetate in the paste-like copper particle composition, it is 20 minutes at 80 ° C. in nitrogen gas (purity 99.99%) as an inert gas. It heated and measured the volatilization amount of the volatile dispersion medium at this time. Next, the remaining volatile dispersion medium is completely volatilized by heating in a mixed gas of 10% by volume of hydrogen gas and 90% by volume of nitrogen gas as a reducing gas, and the copper particles are sintered, thereby shearing. A test specimen for measuring adhesive strength and a test specimen for measuring volume resistivity were prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 1. From the above results, it was found that this joining method is useful for strongly joining metal members without cracks in the heat-sintered copper particles in the paste-like copper particle composition.

[Comparative Example 1]
In Example 1, in order to volatilize 2- (2-butoxyethoxy) ethyl acetate, which is a volatile dispersion medium in the paste-like silver particle composition, in nitrogen gas (purity 99.99%), which is an inert gas. The mixture was heated at 80 ° C. for 2 minutes, and the volatilization amount of the volatile dispersion medium at this time was measured. Next, the remaining volatile dispersion medium is completely volatilized by heating in air, which is an oxidizing gas, and the silver particles are sintered, so that a specimen for measuring shear bond strength and volume resistivity measurement are obtained. A test specimen was prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 2. From the above results, it was found that many cracks were generated in the sintered product of silver particles in the paste-like silver particle composition.

[Comparative Example 2]
In Example 1, in order to volatilize 2- (2-butoxyethoxy) ethyl acetate, which is a volatile dispersion medium in the paste-like silver particle composition, heating is performed at 80 ° C. for 20 minutes in air as an oxidizing gas, The volatilization amount of the volatile dispersion medium at this time was measured. Next, the remaining volatile dispersion medium is completely volatilized by heating in air, which is an oxidizing gas, and the silver particles are sintered, so that a specimen for measuring shear bond strength and volume resistivity measurement are obtained. A test specimen was prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 2. From the above results, it was found that many cracks were generated in the sintered product of silver particles in the paste-like silver particle composition.

[Comparative Example 3]
In Example 1, in order to volatilize 2- (2-butoxyethoxy) ethyl acetate, which is a volatile dispersion medium in the paste-like silver particle composition, in nitrogen gas (purity 99.99%), which is an inert gas. The mixture was heated at 80 ° C. for 20 minutes, and the volatilization amount of the volatile dispersion medium at this time was measured. Next, by heating in an inert gas, nitrogen gas (purity 99.99%), the remaining volatile dispersion medium is completely volatilized and the silver particles are sintered to measure the shear bond strength. And a specimen for measuring volume resistivity were prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 2. From the above results, it was found that cracks were not generated in the paste-like silver particle composition, but the sinterability of silver particles was low and sufficient shear bond strength and volume resistivity could not be obtained.

[Comparative Example 4]
In Example 4, in order to volatilize 2- (2-butoxyethoxy) ethyl acetate, which is a volatile dispersion medium in the paste-like copper particle composition, it is heated at 80 ° C. for 20 minutes in air as an oxidizing gas, The volatilization amount of the volatile dispersion medium at this time was measured. Next, the remaining volatile dispersion medium is completely volatilized by heating in a mixed gas of 10% by volume of hydrogen gas and 90% by volume of nitrogen gas as a reducing gas, and the copper particles are sintered, thereby shearing. A test specimen for measuring adhesive strength and a test specimen for measuring volume resistivity were prepared.
For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 3. From the above results, it was found that many cracks occurred in the sintered product of the copper particles in the paste-like copper particle composition.

[Comparative Example 5]
In Example 1, in nitrogen gas (purity 99.99%), which is an inert gas for volatilizing 2- (2-butoxyethoxy) ethyl acetate, which is a volatile dispersion medium in the paste-like silver particle composition. Without heating at 80 ° C for 20 minutes, immediately replace the atmosphere with air, then heat in air to completely volatilize the volatile dispersion medium and sinter silver particles to measure shear bond strength And a specimen for measuring volume resistivity were prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 3. From the above results, it was found that many cracks were generated in the sintered product of silver particles in the paste-like silver particle composition.

[Comparative Example 6]
In Example 4, in nitrogen gas (purity 99.99%) which is an inert gas for volatilizing 2- (2-butoxyethoxy) ethyl acetate, which is a volatile dispersion medium in the paste-like silver particle composition. Without heating at 80 ° C. for 20 minutes, immediately replace the atmosphere with a mixed gas of 10% by volume of hydrogen gas and 90% by volume of nitrogen gas as a reducing gas, and then heat in the mixed gas to remove the volatile dispersion medium. By completely evaporating and sintering the copper particles, a test body for measuring shear bond strength and a test body for measuring volume resistivity were prepared.

For these specimens, measurement was made by measuring the material of the substrate and chip used, the shear bonding strength of the metal member, the volume resistivity of the sintered product, the number of cracks in the sintered product, and the oxidation of copper. The results are summarized in Table 3. From the above results, it was found that many cracks were generated in the sintered product of silver particles in the paste-like silver particle composition.

In the metal member joining method of the present invention, the metal members can be joined with a sintered product of metal particles without cracks, so that the substrate of a chip component such as a capacitor, resistor, diode, memory, arithmetic element (CPU) or the like can be used. This is useful for bonding of heat sinks and heat dissipation members.
The method for producing a metal member joined body of the present invention is useful for producing a joined body in which metal members are joined with a sintered product of metal particles having no cracks.

It is a top view of the test body A for shear bond strength measurement in an Example. A silver substrate or copper substrate 1 and a silver chip 3 or copper chip 3 are joined by solid silver or solid copper 2 that is a heat-sintered product of silver particles or copper particles. It is the XX sectional view taken on the line in FIG. It is the photograph which image | photographed the silver sintered compact of the junction part in Example 1 with the X-ray transmission imaging device (model number SJV-2000. Output 60kV) made from Softex Corporation. There are no whitish lines. It is the photograph which image | photographed the silver sintered compact of the junction part in the comparative example 2 with the X-ray transmissive imaging device (model number SJV-2000. Output 60kV) by Softex Corporation. A whitish line is a crack.

Explanation of symbols

A Test specimen for measuring shear bond strength 1 Silver substrate or copper substrate 2 Paste-like silver particle composition or paste-like copper particle composition (solid silver or solid copper after heat sintering)
3 Silver chip or copper chip

Claims (9)

A paste-like metal particle composition comprising (A) a heat-sinterable metal particle having an average particle size greater than 0.1 μm and not more than 50 μm and (B) a volatile dispersion medium is interposed between a plurality of metal members. After volatilizing the amount of the volatile dispersion medium (B) in the paste-like metal particle composition from 10% by weight to less than 100% by heating in an inert gas at 40 ° C. or higher and 200 ° C. or lower, By heating at 70 ° C. or more and 400 ° C. or less in an oxidizing gas or a reducing gas, the volatile dispersion medium (B) remaining in the paste-like metal particle composition is volatilized, and heat-sinterable metal particles ( A) A method for joining metal members, characterized in that the metal members are sintered together and joined to each other. The heat-sinterable metal particles (A) are silver particles or copper particles produced by a reduction method, the volatile dispersion medium (B) is a hydrophilic solvent or an aliphatic hydrocarbon solvent, and the metal member is gold. The metal member joining method according to claim 1, wherein the metal member is made of silver, copper, palladium, platinum, or an alloy of these metals. The oxidizing gas is a mixed gas of oxygen gas of 0.1 volume% to 40 volume% and nitrogen gas of 99.9 volume% to 60 volume%, and the reducing gas is 1 volume% to 40 volume%. 3. The method for joining metal members according to claim 1, wherein the metal member is a mixed gas of hydrogen gas and 99% by volume or less and 60% by volume or more of nitrogen gas. The bonded metal member has a shear bond strength of 5 MPa or more, and the volume resistivity of the sintered product of the heat-sinterable metal particles (A) is 1 × 10 ⁻¹ Ω · cm or less. The metal member joining method according to claim 1, 2, or 3. A paste-like metal particle composition comprising (A) a heat-sinterable metal particle having an average particle size greater than 0.1 μm and not more than 50 μm and (B) a volatile dispersion medium is interposed between a plurality of metal members. After volatilizing the amount of the volatile dispersion medium (B) in the paste-like metal particle composition from 10% by weight to less than 100% by heating in an inert gas at 40 ° C. or higher and 200 ° C. or lower, By heating at 70 ° C. or more and 400 ° C. or less in an oxidizing gas or a reducing gas, the volatile dispersion medium (B) remaining in the paste-like metal particle composition is volatilized, and heat-sinterable metal particles ( A) A method for producing a metal member assembly, comprising sintering a plurality of metal members to join each other. The heat-sinterable metal particles (A) are silver particles or copper particles produced by a reduction method, the volatile dispersion medium (B) is a hydrophilic solvent or an aliphatic hydrocarbon solvent, and the metal member is gold. 6. The method for producing a metal member assembly according to claim 5, wherein the metal member assembly is silver, copper, palladium, platinum, or an alloy of each of these metals. The oxidizing gas is a mixed gas of oxygen gas of 0.1 volume% to 40 volume% and nitrogen gas of 99.9 volume% to 60 volume%, and the reducing gas is 1 volume% to 40 volume%. The method for producing a metal member assembly according to claim 5 or 6, wherein the gas is a mixed gas of hydrogen gas and 99% by volume or less and 60% by volume or more of nitrogen gas. The bonded metal member has a shear bond strength of 5 MPa or more, and the volume resistivity of the sintered product of the heat-sinterable metal particles (A) is 1 × 10 ⁻¹ Ω · cm or less. The method for producing a metal member assembly according to claim 5, 6, or 7. The method for producing a metal member assembly according to claim 5, 6 or 7, wherein the metal member is a metal substrate or an electronic component having a metal part.