JPWO2015162881A1 - Bonding composition and metal bonded body using the same - Google Patents

Abstract

There are provided a bonding composition capable of obtaining a metal bonded body having a dense bonding layer and high bonding reliability at a relatively low bonding temperature, and a metal bonded body using the same. A paste-like bonding composition comprising inorganic particles, an organic component, and a dispersion medium, wherein the inorganic particles have an average particle diameter and a crystallite diameter of 1 to 20 μm and 4 to 40 nm, respectively, and at least the surface of the inorganic particles A bonding composition characterized in that metal particles having a particle diameter of 1 to 100 nm are attached to a part thereof.

Description

  The present invention relates to a bonding composition containing inorganic particles as a main component and a metal bonded body using the same, and more specifically, a relatively low bonding between a dense bonded layer and a metal bonded body having high bonding reliability. The present invention relates to a bonding composition that can be obtained at a temperature and a metal bonded body using the same.

  Conventionally, a solder, a conductive adhesive, a silver paste, an anisotropic conductive film, and the like are used for mechanically and / or electrically and / or thermally joining a metal part and a metal part. These conductive adhesives, silver pastes, anisotropic conductive films, and the like may be used when joining not only metal parts but also ceramic parts and resin parts. For example, bonding of light emitting elements such as LEDs to a substrate, bonding of a semiconductor chip to a substrate, bonding of these substrates to a heat dissipation member, and the like can be given.

  Especially, the adhesive agent, paste, and film containing the conductive filler which consists of solder and a metal are used for joining the part which needs an electrical connection. Furthermore, since metals generally have high thermal conductivity, adhesives, pastes, and films containing these solders and conductive fillers may be used to increase heat dissipation.

  On the other hand, for example, when a high-luminance lighting device or a light-emitting device is manufactured using a light-emitting element such as an LED, or a semiconductor device is manufactured using a semiconductor element that operates at a high temperature and is called a power device. In some cases, the amount of heat generation tends to increase. Attempts have been made to improve the efficiency of devices and elements to reduce heat generation. However, at present, sufficient results have not been achieved, and the operating temperature of devices and elements has risen.

  Further, from the viewpoint of preventing device damage during bonding, a bonding material that can ensure sufficient bonding strength at a low bonding temperature (for example, 300 ° C. or lower) is required. Therefore, the bonding material for bonding devices and elements is required to have heat resistance that can withstand the increase in operating temperature due to the operation of the device after bonding and maintain sufficient bonding strength as the bonding temperature decreases. However, there are many cases where conventional bonding materials are not sufficient. For example, solder joins members through a process of heating the metal to the melting point or higher (reflow process). Generally, the melting point is inherent to the composition, so heating (joining) when trying to increase the heat-resistant temperature. The temperature will rise.

  Furthermore, when several layers of elements and substrates are bonded using solder, it is necessary to go through the heating process for the number of layers to be overlapped. In order to prevent melting of the already bonded portion, the solder used for the next bonding It is necessary to lower the melting point (joining temperature) of the solder, and the number of types of solder composition is required by the number of layers to be overlaid, which makes handling complicated.

  Conventionally, solder containing lead has been used as high-temperature solder used at high operating temperatures. Since lead is toxic, the trend toward solder-free solder is remarkable. Since there is no other good alternative material for high-temperature solder, lead solder is still used, but from the viewpoint of environmental problems, a bonding material that does not use lead is eagerly desired.

  In contrast, for example, in Patent Document 1 (Japanese Patent No. 4928639), silver nanoparticles having an average primary particle diameter of 1 to 200 nm and coated with an organic substance having 6 carbon atoms, and at least oxydiacetic acid or A bonding material including a flux component having one of malonic acid and a dispersion medium is disclosed, and the bonding force is further improved by adding particles having an average particle size of 0.5 to 3.0 μm to the bonding material. .

  Moreover, in patent document 2 (patent 5151150 gazette), the particle size with which the surface was coat | covered with the organic substance containing 1 or more types of functional groups chosen from the group of carboxylic acids, alcohol, and amines is 1 nm-5 micrometers. Metal particles and silver oxide particles, and the total weight ratio of the metal particles and silver oxide in the composition is 70% to 95%. The range of the weight ratio is greater than 0 and less than 400 with respect to the metal particles coated on the surface, and heat is generated between 100 ° C. and 140 ° C. when heated in the atmosphere at a heating rate of 1 ° C./min. A bonding material characterized by having a peak is disclosed. In the bonding material, sintering with metal particles is achieved by reducing silver oxide particles.

  Furthermore, in patent document 3 (Unexamined-Japanese-Patent No. 2011-21255), the composite metal nanoparticle which formed the organic coating layer around the metal nucleus of average particle diameter X (nm), and average particle diameter d (nm) Containing metal nanofiller particles and metal filler particles having an average particle diameter D (nm) as a metal component, having a first relationship of X <d <D and a second relationship of X <d <100 (nm), Disclosed is a composite nanometal paste characterized in that composite metal nanoparticles, metal nanofiller particles and metal filler particles are densely sintered when an organic coating layer is diffused by firing to form a metal layer. Yes. In the composite nanometal paste, a dense fired film can be obtained by filling the voids formed by metal particles having a large particle size with metal particles having a small particle size.

Japanese Patent No. 4928639 Japanese Patent No. 5151150 JP 2011-21255 A

  However, the bonding material described in Patent Document 1 does not have a sufficiently dense bonding layer, and does not ensure bonding reliability (for example, bonding strength after a heat cycle is applied). In addition, the bonding material described in Patent Document 2 has a large volume shrinkage of silver oxide particles during the bonding process, and it is difficult to control the thickness of the bonding layer and the voids between the particles constituting the bonding layer. Can not get enough reliability. Furthermore, in the composite nanometal paste described in Patent Document 3, the portion where large particles are in contact with each other does not sinter at a low temperature. Therefore, in order to obtain sufficient bonding strength, it is necessary to fire at a high temperature of 350 ° C. or higher. .

  In view of the above problems in the prior art, an object of the present invention is to provide a bonding composition capable of obtaining a dense bonded layer and a metal bonded body having high bonding reliability at a relatively low bonding temperature, and The object is to provide a metal joined body used.

  As a result of intensive studies on the inorganic particles contained in the bonding composition in order to achieve the above object, the present inventor uses the inorganic particles having an appropriate crystallite size to achieve the above object. As a result, the present invention was reached.

That is, the present invention
A paste-like bonding composition comprising inorganic particles, an organic component, and a dispersion medium,
The average particle size (P _L ) and crystallite size (C _L ) of the inorganic particles are 1 to 20 μm and 4 to 40 nm, respectively.
Metal particles having a particle diameter (P _S ) of 1 to 100 nm are attached to at least a part of the surface of the inorganic particles;
A bonding composition is provided.

Metal particles having a particle diameter (P _S ) of 1 to 100 nm on at least a part of the surface of the inorganic particles having an average particle diameter (P _L ) and a crystallite diameter (C _L ) of 1 to 20 μm and 4 to 40 nm, respectively. As a result, the dense bonding layer can be formed at a relatively low bonding temperature (for example, 300 ° C. or lower). Said inorganic particle may be comprised with the metal, and may be comprised with the same metal seed | species as said metal particle.

The average particle diameter (P _L ) of the inorganic particles can be measured by a dynamic light scattering method or a small angle X-ray scattering method. In addition, as another method for measuring the average particle diameter (P _L ), it can be measured from a photograph taken using a scanning electron microscope or a transmission electron microscope. The particle size of the metal particles attached to the surface of the inorganic particles (P _S) can be measured from the observed image using a scanning electron microscope or a transmission electron microscope.

When the dynamic light scattering method is used, the average particle diameter can be expressed by a volume-based median diameter (D50) measured by a dynamic light scattering particle size distribution analyzer LB-550 manufactured by Horiba, Ltd. Specifically, a few drops of the inorganic particle dispersion are dropped into 10 ml of the dispersion medium, and the sample for measurement is prepared by vibrating by hand or by ultrasonic dispersion. Next, 3 ml of the measurement sample is put into the cell of LB-550 and measured under the following conditions.
・ Measurement conditions Data reading frequency: 100 times Cell holder temperature: 25 ℃
-Display conditions Distribution form: Standard Number of repetitions: 50 times Particle diameter standard: Volume standard Dispersoid refractive index: 0.200-3.900 (in the case of silver)
Refractive index of dispersion medium: 1.36 (for example, when ethanol is the main component)
・ System condition setting Strength standard: Dynamic
Scattering intensity range upper limit: 10000.00
Scattering intensity range lower limit: 1.00

  However, in this method, accurate measurement becomes difficult when the particle diameter exceeds 5 μm. In such a case, an arithmetic average value of particle diameters of about 50 to 100 particles may be used as the particle diameter from an electron micrograph taken using a laser diffraction scattering method or a scanning electron microscope.

One inorganic particle is composed of a plurality of crystallites (maximum size of a single crystal), and the crystallite diameter (C _L ) of the inorganic particles represents the size of the crystallite. The crystallite diameter (C _L ) of the inorganic particles can be determined by, for example, a wide angle X-ray diffraction method. In the wide-angle X-ray diffraction method, for example, RINT-UltimaIII manufactured by Rigaku Corporation can be used to measure 2θ in the range of 30 to 80 ° by the diffraction method. In this case, the sample may be measured by extending it thinly so that the surface is flat on a glass plate having a depression of about 0.1 to 1 mm in depth at the center. Moreover, what is necessary is just to let crystallite diameter (D) calculated by substituting the half value width of the obtained diffraction spectrum for the following Scherrer formula to be an average particle diameter using JADE made by Rigaku Corporation.
D = Kλ / Bcos θ
Here, K: Scherrer constant (0.9), λ: wavelength of X-ray, B: half width of diffraction line, θ: Bragg angle.

The crystallite diameter (C _L ) of the metal particles attached to at least a part of the surface of the inorganic particles is preferably 4 to 40 nm. By setting the crystallite diameter (C _L ) to 4 to 40 nm, good low-temperature sinterability can be imparted to the metal particles. The crystallite diameter (C _L ) of the metal particles can be determined by, for example, the above-mentioned wide angle X-ray diffraction method.

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

  The inorganic particles and metal particles used in the bonding composition of the present invention are not particularly limited as long as the effects of the present invention are not impaired, but the metal particles are preferably silver particles, and moreover, inorganic More preferably, the particles are also silver particles. Since silver particles are relatively stable, they can be stored for a long time, and can be manufactured at a lower cost than gold particles or palladium particles.

  In addition, when using particles having different particle diameters in the bonding composition, it is necessary to pay attention to uniform dispersibility. If the dispersion is not uniform, the bonding layer becomes porous (bonding reliability decreases). . On the other hand, since the metal composition adheres to the surface of the inorganic particles, the bonding composition of the present invention ensures good dispersibility. As a result, since fusion and sintering of particles proceed uniformly, a dense bonding layer can be obtained (high bonding reliability).

  Further, in the bonding composition of the present invention, when TG-DTA measurement of inorganic particles and organic components in the temperature range from room temperature to 550 ° C. in the atmosphere, the weight increases immediately after the maximum exothermic peak at 150 to 300 ° C. It is preferable to do.

  Generally, since the exothermic peak of DTA is oxidative decomposition of organic matter, it means that the dispersant adhering to the particles is decomposed and the particles are sintered. Due to the heat generated by the rapid sintering, the particles themselves are oxidized instantaneously. However, when silver is used as the particles, it is reduced by the self-reduction of silver, so there is almost no influence of oxidation. When used for bonding applications, it can be assumed that the particles are bonded to the interface of the object to be bonded when sintered, but the increase in the weight suppresses shrinkage due to particle sintering, and pressure is applied during bonding. Even if it does not give, adhesion with a to-be-joined body interface can be secured, and joining without pressure is possible.

  Furthermore, in the bonding composition of the present invention, it is preferable that the maximum increase rate (%) of the weight increase is less than 0.2%.

  When the maximum increase rate is 0.2% or more, the strain of the bonding layer is directly affected. In general, heat is transmitted from the end of the joined body, so that sintering is also started from the end. For this reason, for example, when the bonding area is 2 mm × 2 mm or more, the sintering speed slightly differs between the end and the center. Therefore, when the weight increase rate is 0.2% or more, the bonding layer is distorted at the end and the center. It will be joined in a state. In this case, the heat resistance reliability after joining may be adversely affected.

The method for bonding metal bodies of the present invention is a method of bonding the surfaces of two metal bodies using the bonding composition of the present invention,
The bonding atmosphere is air or air-nitrogen mixed atmosphere,
When the inorganic particles and the organic component are measured by TMA in the temperature range from room temperature to 500 ° C. in the bonding atmosphere, the temperature at which the dimensional change from room temperature is −1.0 to 1.0% is defined as the bonding temperature. To do,
A metal body joining method is provided.

  Bonding without pressure by setting the dimensional change rate from room temperature to -1.0% or more when TMA measurement of inorganic particles and organic components is performed in a temperature range from room temperature to 500 ° C. in a bonding atmosphere. In the case where the bonding is performed, the adhesiveness with the interface of the bonded body can be ensured, and by setting it to 1.0% or less, the residual stress due to the thermal history to the bonded body can be reduced.

  In the metal body bonding method of the present invention, when the TG-DTA measurement is performed on the inorganic particles and the organic component in a temperature range from room temperature to 500 ° C. in the bonding atmosphere, a maximum exothermic peak occurs. It is preferable that the temperature be equal to or higher than the temperature to be used.

  By setting the joining temperature to be equal to or higher than the temperature at which the maximum exothermic peak is generated, the sintering can proceed and the joining can be performed.

The metal joined body of the present invention is
A metal joined body obtained by joining the surfaces of two metal bodies using the joining composition of the present invention,
The thickness of the bonding layer of the metal bonded body is 30 to 150 μm;
A metal joined body is provided.

  Since the bonding layer of the metal bonded body of the present invention is composed of inorganic particles and metal particles, the melting point after sintering is almost the same as that of the bulk material, unlike solder. Therefore, the thermal shock reliability at a higher temperature can be obtained as compared with the bonding layer formed of solder. However, when the upper limit temperature of the thermal shock is 200 ° C. or more, the difference in thermal expansion coefficient between the joined body and the joining layer becomes large, and if the thickness of the joining layer is less than 30 μm, the thermal stress cannot be relaxed and destroyed. End up. On the other hand, when the film thickness of the bonding layer is larger than 150 μm, since the amount of the bonding composition applied increases, it becomes difficult to sinter due to the relatively increasing organic matter, and a dense bonding layer is formed. Can't get.

  Therefore, by setting the thickness of the bonding layer to 30 to 150 μm, the bonding layer becomes dense and thermal stress caused by the difference from the coefficient of thermal expansion of the bonded object can be reduced. As a result, the metal bonded body of the present invention has high bonding reliability.

  According to the present invention, it is possible to provide a bonding composition capable of obtaining a metal bonded body having a dense bonding layer and high bonding reliability at a relatively low bonding temperature, and a metal bonded body using the same.

  Hereinafter, a preferred embodiment of a bonding composition of the present invention and a metal bonded body using the same will be described in detail. In addition, in the following description, only one embodiment of the present invention is shown, and the present invention is not limited by these, and redundant description may be omitted.

(1) Joining composition The joining composition of this embodiment is a paste-like joining composition containing inorganic particles, organic components, and the like. Below, each component of the composition for joining is demonstrated.

(1-1) Inorganic particles Although it does not specifically limit as an inorganic particle of the composition for joining of this embodiment, The electroconductivity of the joining layer obtained using the composition for joining of this embodiment is favorable. Therefore, it is preferable to use a (noble) metal having a smaller ionization tendency than zinc.

  Examples of the metal include at least one of gold, silver, copper, nickel, bismuth, tin, iron, and platinum group elements (ruthenium, rhodium, palladium, osmium, iridium, and platinum). The metal preferably contains at least one metal selected from the group consisting of gold, silver, copper, nickel, bismuth, tin, or platinum group elements, and further has a tendency to ionize more than copper or copper. More preferably, it contains a small (noble) metal, that is, at least one metal selected from the group consisting of gold, silver, copper, and platinum.

  Here, it is most preferable to use silver particles as the inorganic particles because they are relatively stable and can be stored for a long period of time, and can be manufactured at a lower cost than gold particles and palladium particles.

  These metals may be used singly or in combination of two or more. The methods for using these metals in combination include the case of using alloy particles containing a plurality of metals, the metal having a core-shell structure or a multilayer structure. Particles may be used.

  For example, when silver particles are used as the inorganic particles of the bonding composition, the conductivity of the adhesive layer formed using the bonding composition of the present embodiment is good, but silver is considered in consideration of migration problems. Further, by using a bonding composition made of other metals, migration can be made difficult to occur. The “other metal” is preferably a metal in which the ionization column is more noble than hydrogen, that is, gold, copper, platinum, or palladium.

The average particle diameter (P _L ) of the inorganic particles used in the bonding composition is 1 to 20 μm. By using inorganic particles having an average particle size (P _L ) of 1 to 20 μm, volume shrinkage due to sintering can be reduced, and a homogeneous and dense bonding layer can be obtained.

When small particles having an average particle size (P _L ) of less than 1 μm are used, sintering proceeds at a low temperature. However, as the particle size increases, the volume shrinkage increases as the average particle size increases. It becomes impossible to follow the volume shrinkage. As a result, defects such as voids occur in the bonding layer, and the bonding strength and reliability of the bonded body are reduced. On the other hand, when particles having an average particle size (P _L ) larger than 20 μm are used, sintering at a low temperature hardly proceeds, and large voids formed between the particles remain after sintering.

Here, the average particle diameter (P _L ) of the inorganic particles is preferably 1 to 15 μm, and more preferably 1 to 10 μm. The above range is preferable from the viewpoint of proceeding the sintering at a low temperature and reducing the voids formed between the particles as much as possible after the sintering.

As described above, the average particle size (P _L ) of the inorganic particles can be measured by a dynamic light scattering method, a small angle X-ray scattering method, or the like. In addition, as another method for measuring the average particle size (P _L ), an arithmetic average value of particle sizes of about 50 to 100 particles is taken from a photograph taken using a scanning electron microscope or a transmission electron microscope. The method of calculating is mentioned.

The crystallite size (C _L ) of the inorganic particles used in the bonding composition is 4 to 40 nm. By setting the crystallite diameter (C _L ) of the inorganic particles to 4 to 40 nm, sintering proceeds with an increase in the crystallite diameter (C _L ) even at a relatively low bonding temperature (for example, 300 ° C. or less).

However, the inorganic particles having an average particle size (P _L ) of 1 to 20 μm have a surface radius of curvature in the order of microns, and therefore, the particles do not fuse together unless fired at a high temperature. On the other hand, in the inorganic particles used in the bonding composition of the present invention, metal particles having a particle size (P _S ) of 1 to 100 nm are attached to at least a part of the surface of the inorganic particles, and the particle surface At least a part of this has a radius of curvature on the order of nanometers. As a result, the inorganic particles can be fused together at a low temperature.

Here, the crystallite diameter (C _L ) of the inorganic particles is preferably 10 to 40 nm, and more preferably 15 to 40 nm. If the crystallite size is too small, sintering at low temperature tends to proceed, but if it remains as an unsintered portion after joining, the above range is preferable from the viewpoint of heat resistance reliability because it becomes a starting point that changes due to heat.

  It is preferable that the inorganic particles and the metal particles in the bonding composition of this embodiment do not include particles that are thermally decomposed to become metal. For example, when particles such as silver oxide and silver carbonate that are thermally decomposed to become metal are included, when the particles decompose, gas such as oxygen and carbon dioxide and metal particles are generated. Volume shrinkage increases. Since the volume shrinkage makes it difficult to bond without pressure, it is preferable not to use particles that are thermally decomposed to become metal as inorganic particles of the bonding composition.

  Moreover, when TG-DTA measurement is performed on the inorganic particles and the organic component in the temperature range from room temperature to 550 ° C. in the atmosphere, it is preferable that the weight increases immediately after the maximum exothermic peak at 150 to 300 ° C.

  Generally, since the exothermic peak of DTA is an oxidative decomposition of organic matter, it means that the dispersant adhering to the particles is decomposed and the particles are sintered. Due to the heat generated by the rapid sintering, the particles themselves are oxidized instantaneously. However, when silver is used as the particles, it is reduced by the self-reduction of silver, so there is almost no influence of oxidation. When used for bonding applications, it can be assumed that the particles are bonded to the interface of the object to be bonded when sintered, but the increase in the weight suppresses shrinkage due to particle sintering, and pressure is applied during bonding. Even if it does not give, adhesion with a to-be-joined body interface can be secured, and joining without pressure is possible.

  Furthermore, when TG-DTA measurement is performed on the inorganic particles and the organic component in the temperature range from room temperature to 550 ° C., the weight increases immediately after the maximum exothermic peak at 150 to 300 ° C., and the maximum increase rate of the weight increase ( %) Is preferably less than 0.2%.

  When the maximum increase rate is 0.2% or more, the strain of the bonding layer is directly affected. In general, heat is transmitted from the end of the joined body, so that sintering is also started from the end. For this reason, for example, when the bonding area is 2 mm × 2 mm or more, the sintering speed slightly differs between the end and the center. Therefore, when the weight increase rate is 0.2% or more, the bonding layer is distorted at the end and the center. It will be joined in a state. In this case, the heat resistance reliability after joining may be adversely affected.

(1-2) Metal particles adhering to at least a part of the surface of the inorganic particles As the metal particles, those exemplified as the metal particles among the inorganic particles described above can be used. And when the inorganic particle mentioned above is a metal particle (core metal particle), the said core metal particle may be the same as or different from the metal particle (surface metal particle) adhering to the surface.

  Examples of the metal include at least one of gold, silver, copper, nickel, bismuth, tin, iron, and platinum group elements (ruthenium, rhodium, palladium, osmium, iridium, and platinum). The metal preferably contains at least one metal selected from the group consisting of gold, silver, copper, nickel, bismuth, tin, or platinum group elements, and further has a tendency to ionize more than copper or copper. More preferably, it contains a small (noble) metal, that is, at least one metal selected from the group consisting of gold, silver, copper, and platinum.

  Here, it is most preferable to use silver particles as the metal particles because they are relatively stable and can be stored for a long time, and can be manufactured at a lower cost than gold particles and palladium particles.

  These metals may be used singly or in combination of two or more. The methods for using these metals in combination include the case of using alloy particles containing a plurality of metals, the metal having a core-shell structure or a multilayer structure. Particles may be used.

  The crystallite diameter of the metal particles attached to at least a part of the surface of the inorganic particles is preferably 4 to 40 nm. When the crystallite diameter of the metal particles is 4 to 40 nm, fusion and sintering at a low temperature are more likely to proceed.

  Furthermore, the crystallite diameter of the metal particles is more preferably 7 to 37 nm, and most preferably 10 to 35 nm. By being in this range, fusion and sintering at a low temperature are more likely to proceed.

The average particle diameter (P _S ) of the metal particles is not particularly limited as long as the effect of the present invention is not impaired, but is preferably a nanometer size that causes a melting point drop in the metal particles. More preferably, it is 100 nm. When the average particle diameter (P _S ) of the metal particles is 1 nm or more, a bonding composition capable of forming a good bonding layer is obtained, and the metal particle production is practical without increasing the cost. Moreover, if it is 100 nm or less, the dispersibility of a metal particle does not change easily over time, and it is preferable.

Furthermore, the average particle diameter (P _S ) of the metal particles is more preferably 5 to 80 nm, and most preferably 10 to 70 nm. By being in this range, low temperature sinterability can be ensured, and the dispersant adhering to the particles can be relatively reduced from the specific surface area, so that a good bonding layer can be formed.

  In order for nanometer-sized metal particles to exist stably, a certain amount of organic matter is required on the surface of the metal particles. The organic substance is preferably an amine and / or a carboxylic acid or a polymer dispersant. Since amines and carboxylic acids adsorb functional groups on the surface of the metal particles with moderate strength and prevent mutual contact of the metal particles, they contribute to the stability of the metal particles in the storage state. It is considered that the organic matter adsorbed on the surface of the metal particles moves and / or volatilizes from the surface of the metal particles during heating, thereby promoting the fusion between the metal particles and the bonding with the base material.

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

  The organic component is an organic substance that can adhere to metal particles and prevent aggregation of the metal particles, and is preferably composed of an alkylamine and a polymer dispersant. By attaching an appropriate amount of the polymer dispersant to at least a part of the metal particles, the dispersion stability can be maintained without losing the low-temperature sinterability of the metal particles. The form of adhesion or coating is not particularly defined, but in the present embodiment, an amine is preferably included from the viewpoints of dispersibility and conductivity. The amine is functionally adsorbed on the surface of the metal particles with moderate strength and prevents the metal particles from contacting each other. This contributes to the stability of the metal particles in the storage state. Alternatively, it is considered that the volatilization promotes the fusion of the metal particles and the bonding with the base material.

The amine that can be used here is not particularly limited, and examples thereof include alkylamines (linear alkylamines, which may have a side chain) such as oleylamine, butylamine, pentylamine, hexylamine, and hexylamine. Alkoxyamines such as N- (3-methoxypropyl) propane-1,3-diamine, 2-methoxyethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, cycloalkylamines such as cyclopentylamine, cyclohexylamine, aniline, etc. Primary amines such as allylamine, secondary amines such as dipropylamine, dibutylamine, piperidine, hexamethyleneimine, tertiary amines such as tripropylamine, dimethylpropanediamine, cyclohexyldimethylamine, pyridine, quinoline, Although the number of carbon atoms as such Kuchiruamin can be exemplified by the order of 2 to 20, preferably carbon atoms using an amine of 4-7. Specific examples of the low boiling point amine having 4 to 7 carbon atoms include heptylamine, butylamine, pentylamine, and hexylamine. Since the amine having 4 to 7 carbon atoms moves and / or volatilizes at a relatively low temperature, the low-temperature sinterability of the metal particles can be fully utilized. Since the metal particles have low temperature sinterability, they begin to sinter around inorganic particles (large particles) or to inorganic particles even at low temperatures, promoting the effect of filling the space between the inorganic particles and the sintering speed of the inorganic particles. An effect can be expressed.
The short-chain amine having 5 or less carbon atoms is not particularly limited as long as the distribution coefficient logP is −1.0 to 1.4, and may be linear or branched. You may have a chain. Examples of the short chain amine include ethylamine (−0.3) propylamine (0.5), butylamine (1.0), N- (3-methoxypropyl) propane-1,3-diamine (−0. 6), 1,2-ethanediamine, N- (3-methoxypropyl)-(-0.9), 2-methoxyethylamine (-0.9), 3-methoxypropylamine (-0.5), 3 -Ethoxypropylamine (-0.1), 1,4-butanediamine (-0.9), 1,5-pentanediamine (-0.6), pentanolamine (-0.3), aminoisobutanol (-0.8) and the like are mentioned, among which alkoxyamine is preferably used.

  Further, the amine is not limited to a straight chain, and may have a side chain in order to control the volatilization temperature. In addition, when these organic components are chemically or physically bonded to the metal particles, it is considered that the organic components are changed to anions and cations. In this embodiment, ions derived from these organic components are used. And organic complexes are also included in the organic components.

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

  As long as it does not impair the effect of this invention, as an organic substance adhering to a metal particle, in addition to an amine, it may contain carboxylic acid. The carboxyl group in one molecule of the carboxylic acid has a relatively high polarity and tends to cause an interaction due to a hydrogen bond, but a portion other than these functional groups has a relatively low polarity. Furthermore, the carboxyl group tends to exhibit acidic properties. In addition, when the carboxylic acid is localized (attached) to at least a part of the surface of the metal particle in the bonding composition of the present embodiment (that is, coats at least a part of the surface of the metal particle), the carboxylic acid is organic. The component and the metal particles can be made sufficiently compatible to prevent aggregation between the metal particles (improve dispersibility).

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

  The carboxylic acid may be a compound containing a functional group other than a carboxyl group, such as an amino group, a hydroxyl group, an alkoxy group, a carbonyl group, an ester group, or a mercapto group. In this case, the number of carboxyl groups is preferably equal to or greater than the number of functional groups other than carboxyl groups. Moreover, the said carboxylic acid may be used independently, respectively and may use 2 or more types together. In addition, the boiling point at normal temperature is preferably 300 ° C. or lower, more preferably 250 ° C. or lower. Also, amines and carboxylic acids form amides. Since the amide group is also adsorbed moderately on the surface of the silver particle, the organic component may contain an amide group.

  A commercially available polymer dispersant can be used as the polymer dispersant. Examples of the commercially available polymer dispersant include, for example, Solsperse 11200, Solsperse 13940, Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 20000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse. 28000 (manufactured by Nihon Lubrizol Co., Ltd.); DISPERBYK 142; Dispersic 184, Dispersic 190, Dispersic 2155 EFKA-46, EFKA-47, EFKA-48, EFKA-49 (manufactured by EFKA Chemical); polymer 100, polymer 120, polymer 150, polymer 400, polymer 401, polymer 402, polymer 403, polymer 450, polymer 451, polymer 452, polymer 453 (manufactured by EFKA Chemical Co.); Ajisper PB711, Ajisper PA111, Ajisper PB811, Ajisper PW911 (manufactured by Ajinomoto Co.); Florene DOPA-15B, Florene DOPA-22, Florene DOPA 17, Floren TG-730W, Floren G-700, Floren TG-720W (manufactured by Kyoeisha Chemical Co., Ltd.) and the like. From the viewpoints of low-temperature sinterability and dispersion stability, it is preferable to use Solsperse 11200, Solsperse 13940, Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 28000, Dispersic 142 or Dispersic 2155.

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

  The content of the organic component adhering to the metal particles in the bonding composition of the present embodiment is preferably 0.5 to 50% by mass. If the organic component content is 0.5% by mass or more, the storage stability of the resulting metal bonding composition tends to be improved, and if it is 50% by mass or less, the conductivity of the metal bonding composition is high. There is a good tendency. The more preferable content of the organic component is 1 to 30% by mass, and the more preferable content is 2 to 15% by mass.

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

  The metal particles can be obtained, for example, by mixing a metal ion source and a dispersant and using a reduction method. In this case, the amount of the organic component can be controlled by optimizing the amount of dispersing agent and reducing agent to be added.

  In order to adjust the amount of organic components adhering to the metal particles, heat treatment for the metal particles, washing with acid (sulfuric acid, hydrochloric acid, nitric acid, etc.), washing with a fat-soluble organic solvent such as acetone or methanol, etc. are used. Can do. In addition, an organic component can be removed more efficiently by applying ultrasonic waves during cleaning.

(1-3) Other organic components, etc. The bonding composition of this embodiment may contain unsaturated hydrocarbons. Examples of the unsaturated hydrocarbon include ethylene, acetylene, benzene, acetone, 1-hexene, 1-octene, 4-vinylcyclohexene, cyclohexanone, terpene alcohol, allyl alcohol, oleyl alcohol, 2-palmitoleic acid, petrothelic acid. Oleic acid, elaidic acid, thianic acid, ricinoleic acid, linoleic acid, linoleic acid, linolenic acid, arachidonic acid, acrylic acid, methacrylic acid, gallic acid and salicylic acid.

  Of these, unsaturated hydrocarbons having a hydroxyl group are preferred. The hydroxyl group can be easily coordinated to the surface of the metal particle, and aggregation of the metal particle can be suppressed. Examples of the unsaturated hydrocarbon having a hydroxyl group include terpene alcohol, allyl alcohol, oleyl alcohol, thianic acid, ricinoleic acid, gallic acid, and salicylic acid. Preferably, it is an unsaturated fatty acid having a hydroxyl group, and examples thereof include thianic acid, ricinoleic acid, gallic acid and salicylic acid.

  The unsaturated hydrocarbon is preferably ricinoleic acid. Ricinoleic acid has a carboxyl group and a hydroxyl group, and is adsorbed on the surface of the metal particles to uniformly disperse the metal particles and promote fusion of the metal particles.

  Further, in the bonding composition of the present embodiment, in order not to impair the effects of the present invention, in order to impart functions such as appropriate viscosity, adhesion, drying property, or printability according to the purpose of use, dispersion is performed. Arbitrary component, resin component, organic solvent (part of solid content may be dissolved or dispersed), surfactant, thickener, or surface tension adjuster, etc. Ingredients may be added. Such optional components are not particularly limited.

  As the dispersion medium of the optional components, various types can be used as long as the effects of the present invention are not impaired, and examples thereof include hydrocarbons and alcohols.

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

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

  Examples of the cyclic hydrocarbon include toluene and xylene.

  Further, examples of the alicyclic hydrocarbon include limonene, dipentene, terpinene, terpinene (also referred to as terpinene), nesol, sinene, orange flavor, terpinolene, terpinolene (also referred to as terpinolene), ferrandylene, mentadiene, teleben, Examples thereof include dihydrocymene, moslen, isoterpinene, isoterpinene (also referred to as isoterpinene), clitomen, kautssin, cajeptene, oilimene, pinene, turpentine, menthane, pinane, terpene, and cyclohexane.

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

Examples of the aliphatic alcohol include heptanol, octanol (1-octanol, 2-octanol, 3-octanol, etc.), decanol (1-decanol, etc.), lauryl alcohol, tetradecyl alcohol, cetyl alcohol, 2-ethyl-1- Examples thereof include saturated or unsaturated C _6-30 aliphatic alcohols such as hexanol, octadecyl alcohol, hexadecenol and oleyl alcohol.

  Examples of the cyclic alcohol include cresol and eugenol.

  Further, as the alicyclic alcohol, for example, cycloalkanol such as cyclohexanol, terpineol (including α, β, γ isomers, or any mixture thereof), terpene alcohol such as dihydroterpineol (monoterpene alcohol etc. ), Dihydroterpineol, myrtenol, sobrerol, menthol, carveol, perillyl alcohol, pinocarveol, sobrerol, berbenol and the like.

  The content when the dispersion medium is contained in the bonding composition of the present embodiment may be adjusted according to desired properties such as viscosity, and the content of the dispersion medium in the bonding composition is 1 to 30 mass. % Is preferred. If content of a dispersion medium is 1-30 mass%, the effect of adjusting a viscosity in the range which is easy to use as a joining composition can be acquired. A more preferable content of the dispersion medium is 1 to 20% by mass, and a more preferable content is 1 to 15% by mass.

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

  As the organic solvent, except for those mentioned as the above dispersion medium, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, 2-propyl alcohol, 1,3-propanediol, 1,2-propanediol, 1 , 4-butanediol, 1,2,6-hexanetriol, 1-ethoxy-2-propanol, 2-butoxyethanol, ethylene glycol, diethylene glycol, triethylene glycol, weight average molecular weight in the range of 200 to 1,000 Polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol having a weight average molecular weight in the range of 300 to 1,000, N, N-dimethylformamide, dimethyl sulfoxide, N- Chill-2-pyrrolidone, N, N- dimethylacetamide, glycerin, or acetone and the like may be used each of which alone or in combination of two or more.

  Examples of the thickener include clay minerals such as clay, bentonite or hectorite, for example, polyester emulsion resin, acrylic emulsion resin, polyurethane emulsion resin or emulsion such as blocked isocyanate, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose. , Cellulose derivatives such as hydroxypropylcellulose and hydroxypropylmethylcellulose, polysaccharides such as xanthan gum and guar gum, and the like. These may be used alone or in combination of two or more.

  Moreover, you may add surfactant different from the said organic component. In a multicomponent solvent-based metal particle dispersion, roughness of the coating surface and unevenness of the solid content are likely to occur due to differences in volatilization rate during drying. By adding a surfactant to the bonding composition of the present embodiment, these disadvantages can be suppressed, and a bonding composition that can form a uniform conductive film is obtained.

  The surfactant that can be used in the present embodiment is not particularly limited, and any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used, for example, an alkylbenzene sulfonate. A quaternary ammonium salt etc. are mentioned. Since the effect can be obtained with a small addition amount, a fluorosurfactant is preferable.

  In addition, as a method of adjusting the amount of organic components to a predetermined range, it is easy to adjust by performing heating. Moreover, you may carry out by adjusting the quantity of the organic component added when producing a metal particle, and you may change the washing conditions and frequency | counts after metal particle adjustment. Heating can be performed with an oven or an evaporator, and may be performed under reduced pressure. When performed under normal pressure, it can be performed in air or in an inert atmosphere. Further, the amine (and carboxylic acid) can be added later for fine adjustment of the amount of organic components.

  The viscosity of the bonding composition of the present embodiment may be adjusted as long as the solid content does not impair the effects of the present invention. For example, the viscosity may be in the range of 0.01 to 5000 Pa · S. A viscosity range of 1 to 1000 Pa · S is more preferable, and a viscosity range of 1 to 100 Pa · S is particularly preferable. By setting it as the said viscosity range, a wide method is applicable as a method of apply | coating the composition for joining on a base material.

  Examples of the method for applying the bonding composition on the substrate include dipping, screen printing, spray method, bar coating method, spin coating method, ink jet method, dispenser method, pin transfer method, application method by brush, casting Method, flexo method, gravure method, offset method, transfer method, hydrophilic / hydrophobic pattern method, syringe method and the like can be appropriately selected and employed.

  The viscosity can be adjusted by adjusting the particle size of the metal particles, adjusting the content of the organic substance, adjusting the addition amount of the dispersion medium and other components, adjusting the blending ratio of each component, adding a thickener, and the like. . The viscosity of the bonding composition can be measured, for example, with a cone plate viscometer (for example, a rheometer MCR301 manufactured by Anton Paar).

(2) Manufacture of bonding composition In order to manufacture the bonding composition of the present embodiment, inorganic particles having metal particles attached to at least a part of the surface as the main component and other components are prepared and Need to mix.

Inorganic particles having metal particles attached to at least a part of the surface can be obtained by synthesizing metal particles in the presence of inorganic particles having an average particle size (P _L ) of 1 to 20 μm. For example, when silver particles are used as inorganic particles and fine silver particles are adhered to the surface of the silver particles, commercially available micron-sized silver particles, silver oxalate, and amine are mixed and reacted in a thermostatic bath. The desired inorganic particles can be suitably obtained.

  The method for preparing the metal particles coated with the organic component is not particularly limited, and examples thereof include a method of preparing a dispersion containing metal particles and then washing the dispersion. As a step of preparing a dispersion containing metal particles, for example, a metal salt (or metal ion) dissolved in a solvent may be reduced as described below, and the reduction procedure is based on a chemical reduction method. A procedure may be adopted.

  That is, the metal particles coated with the organic component as described above are, for example, a metal salt of a metal constituting the metal particles, an organic substance as a dispersant, and a solvent (basically an organic system such as toluene, It may be prepared by reducing a raw material liquid (which may be dispersed without dissolving some of the components). By the reduction, metal particles having an organic component attached to at least a part of the surface can be obtained.

  As a starting material for obtaining metal particles coated with organic matter, various known metal salts or hydrates thereof can be used. For example, silver nitrate, silver sulfate, silver chloride, silver oxide, silver acetate, Silver salts such as silver oxalate, silver formate, silver nitrite, silver chlorate and silver sulfide; for example, gold salts such as chloroauric acid, potassium gold chloride and sodium gold chloride; for example, chloroplatinic acid, platinum chloride, platinum oxide, Platinum salts such as potassium chloroplatinate; for example, palladium salts such as palladium nitrate, palladium acetate, palladium chloride, palladium oxide, palladium sulfate, etc., which can be dissolved in a suitable dispersion medium and can be reduced If it is, it will not specifically limit. These may be used alone or in combination.

  The method for reducing these metal salts in the raw material liquid is not particularly limited, and examples thereof include a method using a reducing agent, a method of irradiating light such as ultraviolet rays, electron beams, ultrasonic waves, or thermal energy. Among these, a method using a reducing agent is preferable from the viewpoint of easy operation.

  Examples of the reducing agent include amine compounds such as dimethylaminoethanol, methyldiethanolamine, triethanolamine, phenidone, and hydrazine; for example, hydrogen compounds such as sodium borohydride, hydrogen iodide, and hydrogen gas; for example, carbon monoxide. Oxides such as sulfurous acid; for example, ferrous sulfate, iron oxide, iron fumarate, iron lactate, iron oxalate, iron sulfide, tin acetate, tin chloride, tin diphosphate, tin oxalate, tin oxide, sulfuric acid Low valent metal salts such as tin; for example, sugars such as ethylene glycol, glycerin, formaldehyde, hydroquinone, pyrogallol, tannin, tannic acid, salicylic acid, D-glucose, etc. There is no particular limitation as long as it can be reduced. When the reducing agent is used, light and / or heat may be added to promote the reduction reaction.

  As a specific method for preparing metal particles coated with an organic substance using the metal salt, organic component, solvent, and reducing agent, for example, the metal salt is dissolved in an organic solvent (for example, toluene) to form a metal salt. Examples thereof include a method of preparing a solution, adding an organic substance as a dispersant to the metal salt solution, and then gradually dropping a solution in which the reducing agent is dissolved.

  In addition to the metal particles, the dispersion containing the metal particles coated with the organic component as the dispersant obtained as described above contains a metal salt counter ion, a reducing agent residue and a dispersant. The electrolyte concentration in the entire liquid tends to be high. Since the liquid in such a state has high electrical conductivity, the metal particles are likely to coagulate and precipitate easily. Alternatively, even if precipitation does not occur, the conductivity of the metal salt may deteriorate if the counter ion of the metal salt, the residue of the reducing agent, or an excessive amount of dispersant remaining in the amount necessary for dispersion remains. Therefore, by washing the solution containing the metal particles to remove excess residues, the metal particles coated with an organic substance can be reliably obtained.

  As the washing method, for example, a dispersion containing metal particles coated with an organic component is allowed to stand for a certain period of time, and after removing the resulting supernatant, alcohol (methanol or the like) is added and stirred again. Furthermore, a method of repeating the process of removing the supernatant liquid generated by standing for a certain period of time, a method of performing centrifugation instead of the above standing, a method of desalting with an ultrafiltration device or an ion exchange device, etc. It is done. By removing the organic solvent by such washing, metal particles coated with the organic component of the present embodiment can be obtained.

  The bonding composition is obtained by mixing the above-described inorganic particles, metal particles coated with an organic component, and other components. The mixing method is not particularly limited, and can be performed by a conventionally known method using a stirrer or a stirrer. An ultrasonic homogenizer with an appropriate output may be applied by stirring with a spatula or the like.

  Although the adjustment method of the amount of organic components and the weight reduction rate is not particularly limited, it is easy to adjust by heating. Moreover, you may carry out by adjusting the quantity of the organic component added when producing a metal particle, and you may change the washing conditions and frequency | counts after metal particle adjustment. Heating can be performed with an oven or an evaporator. The heating temperature may be in the range of about 50 to 300 ° C., and the heating time may be several minutes to several hours. Heating may be performed under reduced pressure. By heating under reduced pressure, the amount of organic matter can be adjusted at a lower temperature. When performed under normal pressure, it can be performed in air or in an inert atmosphere. Furthermore, amines and carboxylic acids can be added later for fine adjustment of the organic content.

  In addition, about the organic component contained in the composition for joining, and its quantity, it can confirm by the measurement using TG-DTA / GC-MS made from Rigaku Corporation, for example. The measurement conditions may be adjusted as appropriate. For example, a TG-DTA / GC-MS measurement is performed when a 10 mg sample is held in the atmosphere from room temperature to 550 ° C. (temperature increase rate: 10 ° C./min). Just do it.

  Moreover, after washing | cleaning a metal particle with methanol and making it settle again by centrifugation (for example, 3300 rpm for 2 minutes), particle | grain solid content can be obtained by removing a supernatant liquid and drying under reduced pressure. By measuring TG-DTA / GC-MS about the obtained particle solid content, the organic component adhering to the surface of a metal particle and its quantity can be specified.

(3) Joining method If the composition for joining of this embodiment is used, high shear strength and reliability can be obtained in joining of members accompanied by heating. Here, the bonding reliability means that the mechanical properties and the like of the joined body are maintained for a long period of time. For example, the mechanical properties and the like of the joined body are not easily lowered by application of a large number of heat cycles. I mean.

  As a bonding method using the bonding composition of the present embodiment, for example, the bonding composition is applied between a metal body that is a first bonded member and a metal body that is a second bonded member. The bonding composition application step and the bonding composition applied between the first metal body and the second metal body are baked and bonded at a desired temperature (for example, 300 ° C. or less). The first metal body and the second metal body can be joined by the joining step of forming. At this time, it is possible to apply pressure, but it is one of the advantages of the present invention that a certain degree of bonding strength can be obtained without applying pressure. In addition, when firing, the temperature can be raised or lowered stepwise. It is also possible to apply a surfactant or a surface activator to the surface of the member to be joined in advance.

  As a result of intensive studies, the inventor used the bonding composition of the present embodiment described above as the bonding composition in the bonding composition application step. It has been found that a metal body can be bonded more reliably with high bonding strength (a dense bonding layer is formed), and the obtained bonded body has high bonding reliability.

  Here, “application” of the bonding composition of the present embodiment is a concept that includes both a case where the bonding composition is applied in a planar shape and a case where the bonding composition is applied (drawn) in a linear shape. The shape of the coating film made of the bonding composition in a state before being applied and fired by heating can be changed to a desired shape. Therefore, in the joined body of this embodiment after firing by heating, the joining composition is a concept that includes both a planar joining layer and a linear joining layer. The bonding layer may be continuous or discontinuous, and may include a continuous portion and a discontinuous portion.

  The first metal body and the second metal body that can be used in the present embodiment are not particularly limited as long as they can be joined by applying a bonding composition and firing by heating. However, it is preferable that the member has heat resistance sufficient to prevent damage due to the temperature at the time of joining.

  Examples of materials constituting such a metal body include various metals. The metal member is preferable as the member to be bonded because it is excellent in heat resistance and in affinity with the bonding composition of the present invention in which the inorganic particles are metal. The member to be joined may have various shapes such as a plate shape or a strip shape, and may be rigid or flexible. The thickness of the substrate can also be selected as appropriate. In order to improve adhesion or adhesion, or for other purposes, a member on which a surface layer is formed or a member subjected to a surface treatment such as a hydrophilic treatment may be used.

  In the step of applying the bonding composition to the members to be bonded, various methods can be used. As described above, for example, dipping, screen printing, spraying, bar coating, spin coating, and inkjet It can be used by appropriately selecting from a formula, a dispenser type, a pin transfer method, a brush application method, a casting method, a flexo method, a gravure method, a syringe method, and the like.

  The coated film after coating as described above is baked by heating to a temperature of 300 ° C. or less, for example, within a range that does not damage the member to be bonded, and the bonded body of this embodiment can be obtained. In the present embodiment, as described above, since the bonding composition of the present embodiment is used, a bonding layer having excellent adhesion to a member to be bonded is obtained, and a strong bonding strength is more reliably ensured. can get. The thickness of the bonding layer can be easily controlled by the thickness of the coating film.

  In the present embodiment, when the bonding composition includes a binder component, the binder component is also sintered from the viewpoint of improving the strength of the bonding layer and the bonding strength between the bonded members. The main purpose of the binder component is to adjust the viscosity of the bonding composition for application to various printing methods, and the binder condition may be controlled to remove all the binder component.

  The method for performing the firing is not particularly limited. For example, the temperature of the joining composition applied or drawn on a member to be joined using a conventionally known oven or the like is, for example, 300 ° C. or less. It can join by baking. The lower limit of the firing temperature is not necessarily limited, and is preferably a temperature at which the members to be joined can be joined and does not impair the effects of the present invention. Here, in the bonding composition after firing, in order to obtain as high a bonding strength as possible, the remaining amount of the organic matter is preferably small, but a part of the organic matter remains within the range not impairing the effect of the present invention. It does not matter.

  Here, in the method for bonding metal bodies of the present invention, when the bonding atmosphere is air or an air-nitrogen mixed atmosphere, and TMA measurement of inorganic particles and organic components in the temperature range from room temperature to 500 ° C. under the bonding atmosphere, It is preferable to set the temperature at which the dimensional change rate from room temperature is −1.0 to 1.0% as the bonding temperature.

  Bonding without pressure by setting the dimensional change rate from room temperature to -1.0% or more when TMA measurement of inorganic particles and organic components is performed in a temperature range from room temperature to 500 ° C. in a bonding atmosphere. In the case where the bonding is performed, the adhesiveness with the interface of the bonded body can be ensured, and by setting it to 1.0% or less, the residual stress due to the thermal history to the bonded body can be reduced.

  In the metal body bonding method of the present invention, when the TG-DTA measurement of inorganic particles and organic components is performed at a bonding temperature in a temperature range from room temperature to 500 ° C. in a bonding atmosphere, a maximum exothermic peak occurs. It is preferable to set the temperature or higher.

  By setting the joining temperature to be equal to or higher than the temperature at which the maximum exothermic peak is generated, the sintering can proceed and the joining can be performed.

  In addition, although the organic substance is contained in the bonding composition of the present invention, it does not obtain the bonding strength after firing by the action of the organic substance, unlike the conventional one using thermosetting such as epoxy resin. As described above, sufficient bonding strength can be obtained by fusing the fused metal particles. For this reason, even after bonding, even if the remaining organic matter is deteriorated or decomposed / dissipated in a use environment higher than the bonding temperature, there is no risk of the bonding strength being lowered, and therefore the heat resistance is excellent. Yes.

  According to the bonding composition of the present embodiment, since it is possible to realize a bonding having a bonding layer that exhibits high conductivity even by baking at a low temperature of about 300 ° C., the members to be bonded are relatively heat-sensitive. Can be joined. Further, the firing time is not particularly limited, and may be any firing time that can be bonded according to the firing temperature.

  In this embodiment, in order to further improve the adhesion between the member to be bonded and the bonding layer, a surface treatment of the member to be bonded may be performed. Examples of the surface treatment method include a method of performing dry treatment such as corona treatment, plasma treatment, UV treatment, and electron beam treatment, and a method of previously providing a primer layer and a conductive paste receiving layer on a substrate.

(4) Metal bonded body The metal bonded body of this embodiment can be manufactured using the above-mentioned bonding composition and bonding method. The metal joined body of the present embodiment is a metal joined body in which the surfaces of two metal bodies are joined using the joining composition of the present invention, and the thickness of the joining layer is 30 to 150 μm. Is the body. Since the bonding layer is composed of inorganic particles and metal particles, the melting point after sintering is approximately the same as that of the bulk material, unlike solder. Therefore, it has higher thermal shock reliability at higher temperatures than a bonding layer formed of solder.

  In addition, by setting the thickness of the bonding layer to 30 to 150 μm, the bonding layer becomes dense and thermal stress caused by the difference from the coefficient of thermal expansion of the bonded object can be reduced. It has reliability.

  As mentioned above, although typical embodiment of this invention was described, this invention is not limited only to these. EXAMPLES Hereinafter, although an Example and a comparative example are given and the composition for joining of this invention and the metal conjugate | zygote using the same are further demonstrated, this invention is not limited to these Examples at all.

Example 1
0.05 g of Solsperse 16000 which is a polymer dispersant, 8.0 g of hexylamine (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.), and 0.40 g of dodecylamine (first grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) And were mixed well with a magnetic stirrer. While stirring, 6.0 g of silver oxalate and 10.0 g of silver particles (catalog average particle size: 3 μm) manufactured by Mitsui Mining & Smelting Co., Ltd. were added to increase the viscosity. The resulting viscous material was placed in a constant temperature bath at 120 ° C. and allowed to react for about 15 minutes.

  Next, in order to replace the dispersion medium of the suspension, 10 ml of methanol was added and stirred, and then silver particles whose surfaces were coated with silver fine particles were precipitated and separated by centrifugation, and the supernatant was removed. After repeating the substitution treatment once more, 1 g of tridecanol as a dispersion medium was added to 15 g of the silver particles whose surfaces were coated with the obtained silver fine particles, and the mixture was stirred and mixed, whereby a bonding composition 1 was obtained. The following various evaluation tests were conducted using the bonding composition 1, and the results are shown in Table 1.

[Evaluation test]
(1) Measurement of average particle size (P _L ) of inorganic particles and particle size (P _S ) of metal particles A small amount of the composition 1 for bonding is diluted with 10 ml of toluene, and LB-550 manufactured by Horiba Ltd. is used. It was measured (P _L) in dynamic light scattering (DLS) using. (P _S ) was synthesized and measured without adding silver particles.

(2) Measurement of crystallite diameter (C _L ) of inorganic particles and crystallite diameter (C _S ) of metal particles About bonding composition 1, wide angle X-ray diffraction using RINT-UltimaIII manufactured by Rigaku Corporation Measured by the method. Measurement is performed in the range of 2θ of 30 to 80 °, and the half width of about 38 ° (111 plane) showing the maximum intensity in the obtained diffraction spectrum is substituted into the Scherrer equation, and the crystallite diameter (C _L ) Asked. (C _S ) was synthesized and measured without adding silver particles.

(3) Bonding reliability test The silicon chip which apply | coated to the 5 mm square using the metal mask (plate | board thickness 70 micrometers) on the alumina substrate (20 square mm) which plated the composition 1 for joining to gold | metal | money, and gave gold plating on it (Bottom area 5 mm × 5 mm) was laminated. The obtained laminate was placed in a muffle furnace at room temperature, heated to 300 ° C., and subjected to a baking treatment for 30 minutes. In the firing process, a pressure of 0.5 MPa was applied. A condition where the laminate (metal bonded body) is taken out after natural cooling, put into a thermal shock tester (JTS-615-64A manufactured by Hutec Co., Ltd.), and held at -40 ° C and 250 ° C for 30 minutes each for one cycle. And was taken out at an arbitrary number of cycles. Thereafter, the bonding strength is measured using a bond tester (Model: PTR-1101 manufactured by Reska Co., Ltd.). When the bonding strength after 500 cycles is reduced with respect to the bonding strength at 0 cycle (×), the decrease If not, it was determined as (◯). The thickness of the bonding layer was 50 μm.

(4) Measurement of void fraction An ultrasonic flaw detector (manufactured by Nippon Kraut Kramer Co., Ltd.) for a metal joined body obtained under the same firing conditions as in (3) except that no pressure was applied during the firing treatment. (μ-SDS), the void ratio was evaluated under the conditions of probe: 80 MHz, φ3 mm, PF = 10 mm. Fine adjustment was performed so that the reflection peak at the bonding interface was the highest, and the measurement was performed with the material sound velocity = Cu: 4800 mm / s. In addition, the threshold value of the reflection intensity was set to 55%, and the void ratio was obtained by regarding that as a void.

<< Example 2 >>
8.0 g of 3-ethoxypropylamine (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 0.40 g of dodecylamine (first grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) are mixed and fully mixed with a magnetic stirrer. Stir. While stirring, 6.0 g of silver oxalate and 10 g of Mitsui Mining & Mining silver particles (reduced powder, D50 = 1.5 μm) were added to increase the viscosity. The resulting viscous material was placed in a constant temperature bath at 120 ° C. and allowed to react for about 15 minutes. In order to replace the dispersion medium of the suspension, 10 ml of methanol was added and stirred, and then silver particles whose surfaces were coated with silver fine particles were precipitated and separated by centrifugation, and the supernatant was discarded. After repeating this operation once more, 1 g of tridecanol as a dispersion medium was added to 15 g of silver particles whose surfaces were coated with silver fine particles, and the mixture was stirred and mixed to obtain a bonding composition 2. The following various evaluation tests were performed using the bonding composition 2, and the results are shown in Table 2.

[Evaluation test]
(1) Bonding strength measurement The bonding composition 2 is applied to a gold-plated copper plate (20 mm square) in a 5 mm square using a metal mask, and a gold-plated Si chip (bottom area 5 mm × 5 mm) is laminated thereon. did. Thereafter, the obtained laminate was put in a reflow furnace (manufactured by Thin Apex), and baked at a maximum temperature of 230 ° C. for 60 minutes in total from the temperature rise to the removal in the atmosphere. In the firing process, no pressure was applied and no pressure was applied. After taking out the laminate, a bonding strength test was performed at room temperature using a bond tester (manufactured by Reska).

(2) Void ratio measurement During the firing treatment, the laminated body to which no external force was applied was evaluated for voids using an ultrasonic flaw detector (probe 80 MHz, φ3 mm, PF = 10 mm) manufactured by Nippon Kraut Kramer. Fine adjustment was made so that the reflection peak at the joint interface was highest, and the measurement was made with the material sound velocity = Cu: 4800 mm / s. The void ratio was set to a threshold value of 55% for reflection intensity, and the void ratio was regarded as a void.

(3) High temperature reliability The laminate fired in (1) is put into a thermal shock tester (manufactured by Hughtech), and the cycle of holding at −40 ° C. and 200 ° C. for 10 minutes, respectively, is taken as one cycle and taken out at an arbitrary number of cycles. It was. When the void ratio after 20 cycles greatly increased with respect to 0 cycles, it was judged as “X”, when some increase was observed, “△”, and when not changed, “good”.

(4) High-temperature reliability on a non-plated Cu substrate Si chip coated with gold on the non-plated oxygen-free copper plate (20 mm square) using a metal mask. (Bottom area 5 mm × 5 mm) was laminated. Thereafter, the laminate was put into a reflow furnace (manufactured by Thin Apex), and was fired at a maximum temperature of 250 ° C. for 60 minutes in total from raising temperature to taking out while flowing nitrogen. The oxygen concentration after firing was 0.1%. In the firing process, no pressure was applied and no pressure was applied. After taking out the laminated body, a bond strength test and a thermal shock test at room temperature using a bond tester (manufactured by Reska Co., Ltd.) were performed. The thermal shock test was performed using a thermal shock tester manufactured by Hutec, and the cycle of holding for 10 minutes at −40 ° C. and 200 ° C. was taken as 1 cycle, and the thermal shock test was taken out at an arbitrary number of cycles. When the void ratio after 20 cycles greatly increased with respect to 0 cycles, it was judged as “X”, when some increase was observed, “△”, and when not changed, “good”.

(5) Measurement of dimensional change rate TMA (manufactured by Rigaku Corporation, TMA8310) was used for a test piece prepared by inserting 1 g of the bonding composition 1 containing no dispersion medium into a 5 × 20 mm die and pressing at 20 kN. Evaluation was performed. Measurement was performed from room temperature to 500 ° C. in the atmosphere at a temperature rising rate of 5 ° C./min, and the rate of change of the test piece length from room temperature was taken as the dimensional change rate.

Example 3
A bonding composition 3 was prepared in the same manner as in Example 2 except that 3-methoxypropylamine (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 3-ethoxypropylamine. Evaluation was performed. The obtained results are shown in Table 2.

Example 4
Except that butyl carbitol acetate was used instead of tridecanol, the bonding composition 4 was prepared in the same manner as in Example 3, and various evaluations were performed. The obtained results are shown in Table 2.

Example 5
A bonding composition 5 was prepared in the same manner as in Example 3 except that Mitsui Metals Mining's silver particles (reduced powder, D50 = 3.0 μm) were used instead of 1.5 μm silver particles. Evaluation was performed. The obtained results are shown in Table 2.

Example 6
Except that the nitrogen flow rate was adjusted by bonding to the Cu substrate and the oxygen concentration after firing was set to 1%, the bonding composition 6 was adjusted in the same manner as in Example 3, and various evaluations were performed. The obtained results are shown in Table 2.

Example 7
Except that the nitrogen flow rate was adjusted by bonding with the Cu substrate and the oxygen concentration after firing was 5%, the bonding composition 7 was adjusted in the same manner as in Example 3, and various evaluations were performed. The obtained results are shown in Table 2.

Example 8
Except that the maximum temperature of the baking treatment was 250 ° C., the bonding composition 8 was prepared in the same manner as in Example 2, and various evaluations were performed. The obtained results are shown in Table 3.

≪Comparative example 1≫
A comparative bonding composition 1 was prepared in the same manner as in Example 1 except that silver particles having an average particle diameter of 0.3 μm were used instead of silver particles having an average particle diameter of 3 μm. Various evaluations were made. The obtained results are shown in Table 1.

«Comparative example 2»
0.40 g of Solsperse 16000 which is a polymer dispersant, 2.0 g of hexylamine (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and 0.40 g of dodecylamine (manufactured by Wako Pure Chemical Industries, Ltd., reagent first grade) And were mixed well with a magnetic stirrer. Here, 6.0 g of silver oxalate was added with stirring to increase the viscosity. The obtained viscous substance was placed in a thermostatic bath at 100 ° C. and allowed to react for about 15 minutes.

  Next, in order to replace the dispersion medium of the suspension, 10 ml of methanol was added and stirred, and then silver fine particles were precipitated and separated by centrifugation, and the supernatant was removed. 1 g of dihydroterpinyl acetate as a dispersion medium was added to 5 g of the obtained silver fine particles and mixed by stirring to obtain a silver colloidal dispersion. To remove impurities such as organic and inorganic components adhering to Mitsui Kinzoku Co., Ltd. silver particles (catalog average particle size: 3 μm), weigh 10 g of silver particles and add 0.1 ml of nitric acid with a concentration of 35%. The solution was added to 50 ml of an aqueous solution made up to 100 ml with ion-exchanged water. After the ultrasonic treatment, silver particles were settled by centrifugation and the supernatant was removed. Thereafter, methanol was removed by a diaphragm pump, and the obtained silver particles and 0.5 g of dihydroterpinyl acetate were mixed in a silver colloidal dispersion to obtain a comparative bonding composition 2. Various evaluations were performed in the same manner as in Example 1, and the results are shown in Table 1.

«Comparative Example 3»
A comparative bonding composition 3 was prepared in the same manner as in Example 2 except that the silver particles having an average particle diameter of 1.5 μm were changed to silver particles (reduced powder, D50 = 8.5 μm) manufactured by Mitsui Mining & Mining. Various evaluations were performed. The obtained results are shown in Table 3. In Table 3, when the bonding strength is 20 MPa or more, ◯, and when less than 20 MPa, ×.

  When the bonding composition 1 containing particles in which silver fine particles having an average particle diameter of 45 nm are attached to the surface of silver particles having an average particle diameter of 3.0 μm is used, the void ratio of the bonding layer is as extremely low as 1%. , Has high bonding reliability. In contrast, in the case of the comparative bonding composition 1 using silver particles having a small average particle size of 0.3 μm, although the surface has silver fine particles having an average particle size of 45 nm, the void ratio is 50%. However, sufficient bonding reliability is not obtained. Further, a composition for comparative joining, which contains both silver fine particles having an average particle diameter of 50 nm and silver particles having an average particle diameter of 3.0 μm, but is not designed so that the silver fine particles adhere to the surface of the silver particles. Even when 2 is used, the void ratio is as large as 20%, and sufficient bonding reliability is not obtained.

  Using the bonding composition 1, a metal bonded body in which the thickness of the bonding layer was changed in the range of 10 to 200 μm was produced in the same manner as in Example 1. A joining reliability test was performed on the metal joined body, and the obtained results are shown in Table 4. The thickness of the bonding layer was controlled by the amount of the bonding composition 1 applied.

  When the bonding composition 2 to the bonding composition 7 of the present invention in which an increase in weight is recognized after the DTA peak is used, the bonding strength is high, a low void ratio, and good high-temperature reliability of 20 MPa or more. I understand that. In addition, this characteristic is maintained not only for the Cu substrate subjected to Au plating but also for the Cu substrate not subjected to Au plating.

  The joining composition 2 and the joining composition 8 that do not contain a dispersion medium exhibit extremely small dimensional change rates, and the joining composition 2 and the joining composition 3 were used, and the metal body joining method of the present invention was used. Example 2 and Example 8 have high joint strength and high temperature reliability. On the other hand, in Comparative Example 3, the void ratio is high, and the bonding strength and the high temperature reliability are not sufficiently obtained.

  When the thickness of the bonding layer is in the range of 30 to 150 μm, high bonding reliability is obtained. On the other hand, when the thickness of the bonding layer is less than 30 μm (10 μm and 20 μm), and when it is larger than 150 μm (200 μm), the bonding strength is reduced by the thermal shock test of 500 cycles, Bonding reliability is not obtained.

Claims (5)

A paste-like bonding composition containing inorganic particles, an organic component and a dispersion medium,
The average particle diameter and crystallite diameter of the inorganic particles are 1 to 20 μm and 4 to 40 nm, respectively.
Metal particles having a particle diameter of 1 to 100 nm are attached to at least a part of the surface of the inorganic particles;
A bonding composition characterized by the above. The crystallite diameter of the metal particles is 4 to 40 nm,
The bonding composition according to claim 1, wherein: The metal particles are silver particles;
The bonding composition according to claim 1 or 2, wherein: The inorganic particles are silver particles;
The bonding composition according to claim 1 or 2, wherein: A metal joined body obtained by joining the surfaces of two metal bodies using the joining composition according to claim 1,
The thickness of the bonding layer of the metal bonded body is 30 to 150 μm;
A metal joined body characterized by.