JP2024045500A - Metal particle sintered body and bonded body having a metal layer made of a metal particle sintered body - Google Patents

Abstract

[Problem] To provide a technology for improving the bonding strength between a sintered body made from low-temperature sinterable precious metal particles and a substrate. [Solution] The technology disclosed herein provides a sintered body of metal particles. The metal particle sintered body contains a metal component and a sulfur component, and is characterized in that a compound containing elemental sulfur (S) is detected as a pyrolysis product. [Selected Figure] Fig. 27

Description

The present invention relates to a metal particle sintered body and a joined body including a metal layer made of the metal particle sintered body. The present invention also relates to a method for manufacturing the metal particle sintered body and the joined body.

Various articles include a bonded body having a metal layer containing a metal component on the surface of a base material. Such a metal layer may contain metal fine particles depending on the use of the joined body. For example, Patent Document 1 describes that a primer layer (resin layer) is formed on the surface of a base material, and noble metal nanoparticles are arranged on the primer layer.
Incidentally, in recent years, research and development of noble metal fine particles and materials prepared in the form of a paste (slurry) containing the noble metal fine particles have been actively conducted for various uses.
For example, so-called "brazing material or solder" has conventionally been used as a bonding material for bonding semiconductor elements. In semiconductor element bonding, high reliability, high heat dissipation, and low loss are required, and highly reliable AuSn alloy solder and Au bump technology are used. However, in bonding using brazing filler metal or solder, damage to the members and elements to be bonded is a problem due to severe conditions such as high temperatures exceeding 300° C. and pressurization. For this reason, in recent years, instead of using brazing filler metals or solder, there have been efforts to develop low-temperature sintering paste materials that utilize surface activation through micronization of metal particles, as well as paste materials in which conductive materials are dispersed in a resin matrix. (for example, Patent Document 2).

As low-temperature sintering materials, many paste materials mainly made of nano-sized or submicron-sized particles of precious metals (precious metal particles) have been developed. Furthermore, in recent years, there has been an increasing demand for paste materials mainly made of gold particles that can be used in environments that require higher reliability.
The above-mentioned noble metal fine particles have a high surface energy and tend to aggregate easily. Therefore, efforts have been made to prevent the aggregation of the noble metal fine particles. For example, in Patent Document 2 and Non-Patent Document 1, submicron particles with a particle size of 100 nm or more are used to avoid particle aggregation. In addition, for example, Patent Document 3 considers a method of preventing the aggregation of the noble metal fine particles by applying some kind of compound (also referred to as a protective agent here) to the surface of the noble metal fine particles.

JP 2018-48382 A Patent No. 5613253 Japanese Patent Application Publication No. 2013-001954

Chem. Mater., Vol. 16 (No. 13), 2004, pp. 2509

For example, in order to achieve high reliability and high heat dissipation in bonding materials for semiconductor devices, it is necessary to improve the low-temperature sintering properties of precious metal fine particles and create a sintered body with high density and high crystallinity through low-temperature treatment. An example of this approach is to create a.
However, if the low-temperature sinterability of the noble metal fine particles is improved, sintering of the noble metal fine particles will proceed extremely easily. On the other hand, this also means that sintering of the noble metal fine particles progresses before bonding with the base material progresses, which can be a problem from the viewpoint of bonding with the base material. Naturally, the noble metal fine particles after sintering have a greatly reduced specific surface area, and have lost their activity to cause diffusion with the base material. In addition, sintered noble metal particles that are not bonded to the base material usually warp or distort, which reduces adhesion to the base material, and it is difficult to bond to the base material even if heat treatment is continued in this state. It is.
Therefore, in order to bond sufficiently strongly a sintered body made using noble metal fine particles having high low-temperature sinterability and a base material, further studies are required.

Therefore, the present invention was created to solve the above problems, and its purpose is to improve the bonding strength between a sintered body (sintered layer) made from low-temperature sinterable precious metal particles and a substrate.

The present inventor has developed a method for connecting the base material and the precious metal sintered body by interposing a metal layer mainly composed of metal and containing a sulfur component between the sintered body (sintered layer) made of the precious metal. It was discovered that the bonding strength with the body was significantly improved, and the present invention was completed.

According to the technology disclosed herein, a sintered body of metal particles is provided. The metal particle sintered body contains a metal component and a sulfur component, and a compound containing the sulfur (S) element is detected as a thermal decomposition product.
In one preferred embodiment, the sulfur component is a sulfur-containing organic compound.
Furthermore, in a preferred embodiment, the compound containing the sulfur (S) element contains at least one of benzothiophene and 2-methylbenzothiophene.
According to this configuration, as will be described later, a noble metal sintered layer is formed on the metal particle sintered body by sintering the noble metal fine particles on the metal particle sintered body. The above configuration can strongly bond the metal particle sintered body and the noble metal sintered layer. As a result, the bond between the base material and the noble metal sintered layer can be strengthened.

Further, preferably, the noble metal element is a gold (Au) element.
The above configuration is suitable when the noble metal sintered layer is a gold sintered layer.

According to the technology disclosed herein, there is provided a bonded body including a substrate and a metal layer. The metal layer is formed on at least a portion of a surface of the substrate. The metal layer is made of the metal particle sintered body.
According to this configuration, a precious metal sintered layer is formed on the metal layer by sintering the precious metal fine particles on the metal layer. The above configuration can strongly bond the metal layer and the precious metal sintered layer. In turn, the bond between the base material and the precious metal sintered layer can be strengthened.

According to the technology disclosed herein, a joined body is provided that includes a metal layer made of a metal particle sintered body and a noble metal sintered layer containing a noble metal element as a main constituent metal element.
The noble metal sintered layer is formed on at least a portion of the surface of the metal layer. At least a portion of the joint between the metal layer and the noble metal sintered layer is sintered.
In one preferred aspect, the density of the noble metal sintered layer is higher than the density of the metal layer.
According to this configuration, the metal particle sintered body (that is, the metal layer) and the noble metal sintered layer can be strongly bonded. In particular, it is suitable when the noble metal sintered layer is formed using noble metal fine particles with high low-temperature sinterability.

Further, in a preferred embodiment, the metal layer is mainly composed of gold (Au).
The above configuration is suitable when the noble metal sintered layer is a gold sintered layer.
Preferably, the metal layer is made of the metal particle sintered body. With this configuration, the noble metal sintered layer formed using noble metal fine particles having high low-temperature sinterability and the metal layer can be strongly bonded.

According to the technology disclosed herein, there is provided a method of manufacturing a joined body including a noble metal sintered layer using the metal particle sintered body as described above.
The manufacturing method disclosed herein includes a base material, a metal layer disposed on at least a portion of the surface of the base material, and a noble metal element provided on the surface of the metal layer as a main constituent metal element. A method for manufacturing a joined body comprising a sintered precious metal layer.
The manufacturing method includes applying an organic material containing a predetermined organometallic compound and a sulfur component to the surface of the base material, and heat-treating the base material coated with the organic material to remove the metal component and the sulfur component. forming a metal layer containing a metal layer on the base material, arranging noble metal fine particles containing a noble metal as a main constituent metal element on the surface of the metal layer, and sintering the noble metal fine particles to obtain noble metal sintering. forming a layer.

According to the manufacturing method having such a configuration, it is possible to provide a joined body in which the base material and the noble metal sintered layer are firmly joined.
According to the manufacturing method, a metal layer containing a sulfur component can be formed on the surface of the base material, and a noble metal sintered layer sintered with the metal layer can be formed on the surface of the metal layer. can.

In a preferred embodiment, the temperature of the heat treatment is 450°C or lower.
According to this configuration, when forming the metal layer, it is possible to suppress the sulfur component from burning through. With the above configuration, a metal layer containing a sulfur component can be formed.

In a preferred embodiment, the fine noble metal particles have at least one of an amine compound and an imine compound held on the surface.
It has been known that the dispersibility of the precious metal fine particles can be improved by having the above-mentioned compound on the surface of the precious metal fine particles. By using the above-mentioned precious metal fine particles, the dispersion stability of the precious metal fine particles is significantly improved in the material containing the precious metal fine particles (typically, a slurry (paste)-like material). This makes it easy to prepare a dispersion with a higher concentration (e.g., a conductor paste), and a denser precious metal sintered layer can be formed at a low temperature.

In a preferred embodiment, the main metal element of the noble metal particles is gold (Au).
Although gold particles, especially precious metal particles, are prone to aggregation and settling, this can be prevented by using amine and imine protective agents that can be decomposed and removed at low temperatures. Therefore, a denser precious metal sintered layer (gold sintered layer) can be obtained at low temperatures.

In one preferred embodiment, the sintering temperature is 300°C or less.
As described above, highly dispersed gold fine particles protected with amines and imines have high sinterability, and therefore a gold sintered layer can be formed at a sintering temperature of 300° C. or lower. Moreover, by setting the sintering temperature to 300° C. or lower, a sulfur component may remain in the metal layer even after forming the noble metal sintered layer. Furthermore, it is applicable to various base materials including those with low heat resistance such as resin films.

The bonded body disclosed herein can be provided by the above-mentioned manufacturing method.
The bonded body includes a dense precious metal sintered layer, and the precious metal sintered layer is firmly bonded to the metal layer by sintering. Therefore, in the bonded body, the bonding strength between the precious metal sintered layer and the base material is significantly improved.

FIG. 2 is a cross-sectional view schematically showing the structure of the joined body disclosed herein. 1 is a graph showing TG-DTA measurement results for a dried water-gold liquid. 1 is a graph showing the results of XRF analysis of sulfur (S) element in the gold layers of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-5. 1 is a pyrolysis GC/MS spectrum obtained for the gold layer of Example 1-2. This is the MS spectrum of peak No. 3 in the pyrolysis GC/MS spectrum of FIG. This is library data (MS spectrum) of sulfur dioxide (SO ₂ ). This is the MS spectrum of peak No. 12 in the pyrolysis GC/MS spectrum of FIG. This is library data (MS spectrum) of benzothiophene. This is the MS spectrum of peak No. 14 in the pyrolysis GC/MS spectrum of FIG. This is library data (MS spectrum) of 2-methylbenzothiophene. This is a FESEM observation image (50,000 times) of noble metal fine particles related to Sample 1. This is a FESEM observation image (50,000 times) of noble metal fine particles related to Sample 2. 1 is an FESEM observation image (50,000 times) of the precious metal microparticles of Sample 3. 1 is an FESEM observation image (50,000 times) of the precious metal microparticles of Sample 4. This is a FESEM observation image (50,000 times) of noble metal fine particles related to Sample 5. 1 is an FESEM observation image (magnification: 50,000) of the precious metal microparticles of Sample 6. 1 is a pyrolysis GCMS spectrum obtained for sample 1. 2 is a pyrolysis GCMS spectrum obtained for sample 2. 2 is a pyrolysis GCMS spectrum obtained for sample 3. 1 is a pyrolysis GCMS spectrum obtained for sample 4. 2 is a pyrolysis GCMS spectrum obtained for sample 5. 1 is a pyrolysis GCMS spectrum obtained for sample 6. This is an MS spectrum of the peak (■) of imine compound A detected in samples 1 to 4. This is an MS spectrum of the peak (■) of imine compound B detected in sample 5. 1 is an MS spectrum of the peak (■) of imine compound C detected in sample 6. 1 shows the MS spectrum (library data) of imine compound B obtained by library search. This is a FESEM observation image (10,000 times magnification) of the zygote of Example 2-2. This is a FESEM observation image (100,000 times) of the zygote of Example 2-2.

Preferred embodiments of the present invention will be described below. Note that matters other than those specifically mentioned in this specification that are necessary for carrying out the present invention can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be carried out based on the contents disclosed in this specification and the technical common sense in the relevant field.
In this specification and claims, when a certain numerical range is described as A to B (A and B are arbitrary numerical values), it means A or more and B or less. Therefore, it includes the case where it is greater than A and less than B.

In this specification and the claims, the term "noble metal fine particles" refers to a group of many fine particles (ie, particles), unless specifically referring to a single grain unit. For example, the noble metal fine particles in "powder material or dispersion containing noble metal fine particles" described below refer to noble metal fine particles as particles, not as single particles. In Japanese, it is ambiguous whether it is singular or plural, so we define it as above to clarify the meaning of "precious metal fine particles."

First, the conjugate disclosed herein will be explained with reference to FIG. 1. FIG. 1 is a cross-sectional view schematically showing the structure of the joined body disclosed herein.
As shown in FIG. 1, the joined body 100 includes at least a metal layer 10. The joined body 100 includes at least one of a noble metal sintered layer 20 and a base material 30 in addition to the metal layer 10 . The structure of the joined body 100 includes, for example, a structure including at least a metal layer 10 and a base material 30, a structure including at least a metal layer 10 and a noble metal sintered layer 20, a structure including at least a metal layer 10, a noble metal sintered layer 20, and a base material. An example is a configuration including a material 30.
For example, when the joined body 100 includes the metal layer 10 and the base material 30, the metal layer 10 is formed on at least a portion of the surface of the base material 30 (one or both surfaces in the lamination direction Z). Further, when the joined body 100 includes the metal layer 10 and the noble metal sintered layer 20, the noble metal sintered layer 20 is provided on at least a part of the surface of the metal layer 10 (on one side or both sides in the stacking direction Z). It is formed.
Note that the number of layers constituting the joined body 100 is not particularly limited. The joined body 100 may include, for example, a plurality of metal layers 10 or a plurality of noble metal sintered layers 20. Moreover, when the joined body 100 includes a plurality of metal layers 10, the plurality of metal layers 10 may be different from each other. When the joined body 100 includes a plurality of noble metal sintered layers 20, the plurality of noble metal sintered layers 20 may be different from each other.

The substrate 30 may be made of any metal or ceramic (including glass) that constitutes various conventionally known substrates, without any particular restrictions. Metal substrates include, for example, substrates made of metals such as aluminum, chromium, iron, nickel, copper, and tungsten, or alloys thereof. Ceramic substrates include substrates made of crystalline or amorphous metal oxides such as silica and alumina. Alternatively, the substrate 30 may be a resin substrate. Resin substrates include, for example, resin substrates such as polyimide.
The detailed composition, shape, dimensions, etc. of the substrate 30 are not particularly limited, and as they do not characterize the present invention, detailed description thereof will be omitted.

The metal layer 10 is made of a metal particle sintered body. The metal particle sintered body contains at least a metal component. When the total weight of the metal particle sintered body is taken as 100 wt%, the proportion of the metal component can be approximately 70 wt% or more (preferably 80 wt% or more, more preferably 90 wt% or more, and even more preferably 95 wt% or more).
The metal element constituting the metal component is not particularly limited, and may be any of various base metal elements and precious metal elements. Specific examples of base metal elements include titanium (Ti), chromium group elements (chromium (Cr), molybdenum (Mo), tungsten (W)), manganese (Mn), iron group elements (iron (Fe), cobalt (Co), nickel (Ni)), copper (Cu), zinc (Zn), tin (Sn), etc. Specific examples of precious metal elements include gold (Au), silver (Ag), palladium (Pd), platinum (Pt), rhodium (Rh), etc.
The metal component may be an alloy of the above metals. The metal component may consist of one of the above metal elements, or may contain two or more of them.

The metal component preferably contains a precious metal element as the main constituent element. Here, the main constituent element refers to the element that constitutes the metal component. Ideally, the elements that constitute the metal component are precious metal elements, but various base metal elements may be included as unavoidable impurities.

The metal particle sintered body may contain a sulfur component in addition to the above metal components. Preferably, the metal particle sintered body contains a sulfur component.
The sulfur component may include at least one of a sulfur-containing inorganic compound and a sulfur-containing organic compound. From the viewpoint of improving the bonding strength with the noble metal sintered layer described later, the sulfur component is preferably a sulfur-containing organic compound.
The content of the sulfur component in the metal particle sintered body is 0.1% by weight or more (for example, 0.5% by weight or more, 1% by weight or more) when the total weight of the metal particle sintered body is 100% by weight. , 2% or more, or 5% or more by weight). Further, the content of the sulfur component may be 20% by weight or less (for example, 15% by weight or less, 10% by weight or less, or 7% by weight or less). Note that the content can be measured, for example, by thermobalance-mass spectrometry (TG-MS).

When the metal particle sintered body is subjected to thermal decomposition, a compound containing elemental sulfur (S) is detected as a thermal decomposition product. As a method of the thermal decomposition, for example, a thermal decomposition GC/MS analysis can be mentioned.
The sulfur component contained in the metal particle sintered body can be detected, for example, by pyrolysis GC/MS analysis. That is, when the metal particle sintered body is subjected to pyrolysis GC/MS analysis under a predetermined condition, a compound containing sulfur (S) element is detected. The compound containing sulfur (S) element may be either a sulfur-containing inorganic compound or a sulfur-containing organic compound.
For the above analysis, a commercially available analytical device can be used without any particular restrictions. Detailed analysis conditions are described in the following examples. The analysis conditions can be appropriately changed as necessary. For example, in the following examples, the pyrolysis temperature is set to 550° C., but is not limited thereto and can be appropriately changed.

Roughly speaking, a metal particle sintered body can be produced by subjecting an organic material for producing the metal particle sintered body to a heat treatment under specified conditions. An example of a specific production method is described in the following paragraphs of this specification and in the Examples below.

The thickness of the metal layer 10 is not particularly limited, but is suitably 0.01 μm or more, preferably 0.025 μm or more, more preferably 0.05 μm or more, for example, 0.1 μm or more. The thickness of the metal layer 10 is suitably 2 μm or less, preferably 1.5 μm or less, more preferably 1.0 μm or less, even more preferably 0.75 μm or less, for example, 0.5 μm or less. . When the thickness of the metal layer 10 is within the above range, a strong bond can be realized between the metal layer 10 and the base material 30. Moreover, the metal layer 10 and the noble metal sintered layer 20 are firmly bonded, and a laminated structure with stable bonding strength can be realized.

The density of the precious metal sintered fine particle layer 20 is higher than the density of the metal layer 10 .
As for the density, for example, as described in the examples below, the ion-milled polished surface of the joined body 100 is observed by FESEM, and the areas of the black voids in the metal layer 10 and the precious metal sintered layer 20 are calculated from the microscopic observation image (e.g., an observation image at 10,000 times magnification) using commercially available image analysis software, and the areas of the black voids in the metal layer 10 and the precious metal sintered layer 20 are calculated using the following formula:
Density (%) = 1 - (void area/total area)%
It can be calculated using:

The noble metal sintered layer 20 contains a noble metal element as a main constituent element. The type of noble metal element is not particularly limited, but typically may be gold (Au), silver (Ag), palladium (Pd), platinum (Pt), rhodium (Rh), or the like. Here, the main constituent element of the noble metal sintered layer 20 refers to an element that is the main constituent of the noble metal sintered layer 20. The elements constituting the noble metal sintered layer 20 are ideally composed of noble metal elements, but may also contain various base metal elements and nonmetal elements as inevitable impurities.
The main constituent elements of the noble metal sintered layer 20 and the main constituent elements of the metal layer 10 may be different from each other, or may be the same. From the viewpoint of realizing the effects of the present invention more effectively, it is preferable that the main constituent elements of the metal layer 10 and the main constituent elements of the noble metal sintered layer 20 are the same.

The precious metal sintered layer 20 is preferably composed mainly of gold (Au). Ideally, the precious metal sintered layer 20 is composed of gold (Au), but may contain various base metals, inorganic compounds, and organic compounds as unavoidable impurities.

The precious metal sintered layer 20 is made of precious metal fine particles. The precious metal fine particles will be described below.
The noble metal fine particles are noble metal fine particles whose main constituent metal element is a noble metal element, and the type of noble metal is not limited. Typically, gold (Au), silver (Ag), palladium (Pd), platinum (Pt), rhodium (Rh), etc., or alloys thereof can be mentioned. Here, the main constituent metal element refers to the metal element that is the main constituent of the noble metal fine particles. The noble metal fine particles are ideally composed only of noble metal elements, but may contain various metal elements and nonmetal elements as unavoidable impurities. The organic matter content of the noble metal fine particles (referring to the aggregate before firing) measured based on TG-DTA in the total weight (100 wt%) is preferably about 1.5 wt% or less, and particularly preferably 1 wt% or less.
Preferably, the noble metal particles are gold particles whose main constituent metal element is gold (Au). Among noble metal particles, gold particles in particular tend to aggregate and settle, and are therefore suitable for application of the technology disclosed herein.

The noble metal fine particles may or may not have some kind of compound on their surfaces.
When the precious metal fine particles hold a specific compound on their surface, examples of the compound include amine compounds and imine compounds. By holding at least one of the amine compounds and imine compounds on the surface of the precious metal fine particles, the precious metal fine particles have high dispersibility in various organic solvents, and a dense precious metal sintered body (sintered layer) can be obtained by firing the precious metal fine particles at a low temperature of 300° C. or less (for example, about 250 to 300° C.).
In a preferred embodiment, an imine compound is held on the surface of the fine noble metal particles as a protective agent.
Specifically, as in the reaction system described in the examples below, a mixture of a precious metal salt or a precious metal complex (e.g., when the precious metal is gold, chloroauric acid ( _HAuCl4 ) or the like can be used) that is soluble in a specific alcohol-based solvent and serves as the raw material for precious metal microparticles, a sufficient amount of alkylamine (e.g., 3 molar equivalents or more) relative to the precious metal, and an alcohol-based solvent that can dissolve the raw material, such as an alkyl alcohol, is prepared, and the mixture is heated, for example, to 80° C. or higher. This reduces the precious metal ions from the precious metal salt or complex, producing precious metal microparticles.
The reduction treatment time for the precious metal ions can be appropriately set and is not particularly limited, but is preferably, for example, about 0.5 to 5 hours.
The precious metal fine particles generated by the reduction treatment as described above can be collected in the same manner as conventional metal particle collection, and there is no particular restriction. Preferably, the precious metal fine particles generated in the liquid are allowed to settle, and the supernatant is removed by centrifuging. Preferably, washing and centrifugation are repeated multiple times with an appropriate dispersion medium, and the precious metal fine particles are dispersed in the appropriate dispersion medium, thereby obtaining a desired dispersion of the precious metal fine particles. Furthermore, a paste (slurry) composition (e.g., a conductor paste for forming an electrode film, etc.) can be prepared by adding components such as a binder.

In the technology disclosed herein, in the production process of noble metal fine particles by the above-mentioned reduction treatment, alcohol-derived carbonyl compounds (for example, carbonyl compounds such as aldehydes formed by oxidizing alcohol as a solvent) and alkyl amines (primary amines) An imine compound (typically an alkylimine) is produced by dehydration condensation with the noble metal fine particles, and is retained on the surface of the noble metal fine particles. Therefore, on the surface of the noble metal fine particles produced in the reaction system as described above, in addition to the imine compound, there may be organic substances that can be called residues such as alkylamines that did not participate in the production of imine by the dehydration condensation.
Preferably, the peak area of the imine compound determined in pyrolysis GCMS analysis at a pyrolysis temperature of 300°C and the peak area of the amine compound (at a level where the amine compound cannot be detected, that is, when the peak area is 0) It is preferable that the abundance ratio of imine compounds having an amine/imine ratio (A/I ratio), which is an area ratio of 1 or less with respect to It is particularly preferred to have a high yield of imine compounds with an A/I ratio of 0.6 or less (which can be, for example, 0.01 to 0.2). This can further improve the dispersibility and low-temperature sinterability of the noble metal fine particles.

Preferably, the imine compound produced in the above reaction system (some examples described later will be helpful) and held on the surface of the noble metal fine particles has a relatively small molecular weight, specifically, one with a carbon number Preferably, the alkylimine has a hydrocarbon group having about 10 carbon atoms or less, for example 4 to 10 carbon atoms. For example, the above imine compound has the following structural formula:
R ⁰ R ¹ C=N-(CH ₂ )-R ²
It is a compound represented by R ⁰ , R ¹ and R ² are each independently a partially substituted or unsubstituted alkyl group or hydrogen. A preferred example is one in which R ⁰ is hydrogen, and R ¹ and R ² are each a hydrocarbon group having 3 to 9 carbon atoms (more preferably 3 to 7 carbon atoms).
For example, in the imine compound of the above structural formula, R ⁰ is hydrogen, and R ¹ and R ² are each CH ₃ (CH ₂ ) ₆ , CH ₃ (CH ₂ ) ₄ or CH ₃ (CH ₂ ) ₂ is a specific preferred example.
Such noble metal fine particles that have an imine compound (e.g. alkylimine) with a relatively low molecular weight and a short hydrocarbon group on the surface can be easily released by low-temperature calcination of 300°C or less, so they cannot be densely sintered. Aggregates can be easily produced.

This type of imine compound having a relatively small molecular weight and short chain length can be produced selectively (preferentially) by selecting the alcohol solvent and the primary amine used in the reaction system.
For example, when octanol ( _CH3 ( _CH2 ) _7OH ) is used _as the alcohol solvent and octylamine ( _CH3 ( _CH2 ) _7NH2 ) is used as the primary amine, the imine compound produced may have the above structural formula in which ^R0 is hydrogen and ^R1 and ^R2 are each _CH3 ( _CH2 ) ₆ . Alternatively, when the primary amine is replaced with butylamine ( _CH3 ( _CH2 ) _3NH2 ) in this reaction system, the imine compound produced _may have the above structural formula in which ^R0 is hydrogen and at least one of ^R1 and ^R2 is _CH3 ( _CH2 ) ₂ . Alternatively, in the case where the primary amine in this reaction system is replaced with hexylamine ( _CH3 ( _CH2 ) _5NH2 ), the produced imine compound may have ^the above structural formula in which ^R0 is hydrogen and at least one of ^R1 and _R2 is _CH3 ( _CH2 ) ₄ .
In this manner, by appropriately selecting the alcohol solvent and the amine compound used in the above reaction system, the molecular weight of the generated imine compound (in other words, the composition of R ⁰ , R ¹ , and R ² ) can be varied as appropriate.
As will be apparent from the description of the Examples below, the structure of the produced imine compound can be identified by measuring a pyrolysis GCMS spectrum.

Regarding the particle size distribution of the precious metal microparticles, it is preferable that the ratio of the Z-average particle size (DDLS) based on a dynamic light scattering (DLS) method measured in a state dispersed in a specified medium to the average particle size (DSEM) based on a field emission scanning electron microscope image (FE-SEM image), DDLS/DSEM, is 2 or less.
DDLS/DSEM is one of the suitable indicators of the degree of adhesion of the precious metal fine particles, in other words, the dispersibility. The precious metal fine particles characterized by such a DDLS/DSEM of 2 or less exhibit particularly good dispersibility and can be suitably used for forming conductors such as fine electrodes. The DDLS/DSEM is more preferably 1.7 or less, and particularly preferably 1.5 or less.
Since the precious metal fine particles having such characteristics have excellent dispersibility, they can contribute to miniaturization of electronic components and thinning of electrodes in the electronic materials field. In addition, the precious metal fine particles having a relatively small average particle size, such as a Z-average particle size (DDLS) of 200 nm or less, can be particularly preferably used for forming conductors such as fine electrodes, and can further preferably advance the thinning of electrodes and the improvement of reliability. It is more preferable that the DDLS is 150 nm or less, and particularly preferably, for example, 50 nm or more and 150 nm or less.

By dispersing noble metal fine particles in a dispersion medium consisting of an appropriate aqueous solvent or organic solvent, dispersions for various uses can be obtained.
For example, by dispersing noble metal fine particles in a predetermined organic solvent as a medium for dispersing the noble metal fine particles, and adding components such as a binder, a conductive material, and a viscosity modifier as necessary, a paste (or slurry) is formed. ) can provide a composition (conductor paste) prepared as follows. As described above, such a conductive paste contains noble metal fine particles whose Z average particle size is controlled in the submicron range, so that a sufficiently thin electrode can be suitably formed.
Note that the dispersion medium for the conductive paste may be any medium as long as it can disperse the conductive powder material well, as in the past, and those used in the conventional preparation of the conductive paste can be used without particular restriction. . For example, organic solvents include petroleum hydrocarbons (especially aliphatic hydrocarbons) such as mineral spirits, cellulose polymers such as ethyl cellulose, ethylene glycol and diethylene glycol derivatives, toluene, xylene, butyl carbitol (BC), terpineol, etc. It is possible to use one kind or a combination of two or more kinds of high boiling point organic solvents.

A suitable dispersion medium for preparing the above-mentioned dispersion includes a cyclic alcohol having a hydroxyl group on a cyclic chain. By including the cyclic alcohol as a dispersion medium, high dispersion stability can be achieved. Suitable examples include cyclic alcohols having a 5- to 8-membered ring. Examples include terpineol, menthanol (dihydroterpineol), menthol (2-isopropyl-5-methylcyclohexanol), cyclopentanol, cyclohexanol, cycloheptanol, and the like. These cyclic alcohols may be used alone or in combination of two or more. The content of the cyclic alcohol is not particularly limited, but is suitably 10 to 100% by weight, preferably 70 to 100% by weight of the entire dispersion medium.

The thickness of the precious metal sintered layer 20 is not particularly limited, but is preferably 0.5 μm or more (e.g., 0.75 μm or more, 1 μm or more, or 1.5 μm or more). The thickness is preferably 10 μm or less (e.g., 7.5 μm or less, 5 μm or less, or 4 μm or less). By having the thickness of the precious metal sintered layer 20 within the above range, the metal layer 10 and the precious metal sintered layer 20 are firmly bonded to each other, and a laminated structure with stable bonding strength can be realized.

Next, a method for manufacturing the zygote disclosed herein will be explained.
Roughly speaking, the method includes applying an organic material containing a predetermined organometallic compound and a sulfur component to form the metal layer 10 (i.e., metal particle sintered body) on the surface of the base material 30; , heat-treating the base material 30 coated with the organic material under predetermined temperature conditions to form a metal layer 10 containing a metal component and a sulfur component on the base material 30.

Specifically, as described in the examples below, first, a noble metal salt (for example, when the noble metal is gold, gold chloride, etc.) and a sulfur-containing raw material for the metal layer are prepared. A noble metal-organic compound complex (noble metal resinate) is obtained by reacting an organic compound (for example, a sulfur-containing resin such as sulfurized balsam).
Next, this is dissolved in a predetermined organic solvent (for example, commercially available WA oil, etc.) to prepare a metal layer forming material (slurry (paste) material), and applied to the surface of the base material. The coating method is not limited, and conventionally known coating means can be employed. Note that the amount of material applied to the base material may be appropriately adjusted to a sufficient amount to achieve a desired thickness of the metal layer 10. Further, various components such as a binder and a viscosity modifier may be added as necessary.

Next, the applied material is dried to obtain a dry film, and the applied material (here, the dry film) is heat-treated at 450°C or less. This allows the metal layer 10 to be formed on the surface of the substrate 30. If the temperature condition at this time is 450°C or less, the burn-out of the sulfur component can be suppressed. That is, by performing the heat treatment under this temperature condition, the metal layer 10 containing the sulfur component can be formed. The period of the heat treatment is not particularly limited, and can be set appropriately as necessary.
By the above-mentioned procedure, a bonded body including the substrate 30 and the metal layer 10 can be manufactured.

Furthermore, a bonded body including the substrate 30, the metal layer 10, and the precious metal sintered layer 20 can be produced by the following method.
Precious metal particles are arranged on the surface of the metal layer 10 formed as described above. Specifically, a paste (slurry) composition (material) containing precious metal particles is applied onto the surface of the metal layer 10. The application method is not particularly limited, and a conventionally known coating method can be adopted. The amount of material applied to the substrate may be appropriately adjusted to a sufficient amount to achieve the desired thickness of the precious metal sintered layer 20.

Next, the material (i.e., the precious metal fine particles) applied on the surface of the metal layer 10 is sintered (heat treated) in the firing temperature range of the precious metal fine particles. Although it may vary depending on the metal type, the sintering temperature can typically be 200° C. or higher (e.g., 230° C. or higher, 250° C. or higher). This allows at least a portion of the joint between the metal layer 10 and the precious metal sintered layer 20 to be sintered.
The sintering temperature may be adjusted to a temperature at which sulfur components can remain in the metal layer 10. In this case, the temperature may be 450°C or less, 400°C or less, 350°C or less, or 300°C or less. For example, when precious metal fine particles (e.g., gold fine particles) having high low-temperature sinterability are used as the precious metal fine particles, the above temperature can be, for example, 350°C or less, 320°C or less, for example, 300°C or less. Such a temperature range is particularly preferable when a resin base material is used as the base material 30. On the other hand, the above sintering (heat treatment) may be performed in a temperature range at which no sulfur components remain in the metal layer 10, that is, at a temperature above 450°C.
In any of the above cases, the precious metal sintered layer 20 and the metal layer 10 can be firmly bonded to each other. In addition, the base material 30 and the precious metal sintered layer 20 can be firmly bonded to each other.

When manufacturing a bonded body having a metal layer 10 and a precious metal sintered layer 20, for example, a metal particle sintered body is first prepared as the metal layer 10, precious metal particles are placed on the surface of the metal layer 10, and the bonded body is obtained by carrying out heat treatment as described above.

The following examples are given below as examples of the metal particle sintered body and bonded body disclosed herein, but these examples are not intended to limit the present invention.

Example 1: Production of metal particle sintered body
In Example 1, a gold particle sintered body was produced using a commercially available liquid gold liquid. The gold particle sintered body was formed on the surface of a substrate to produce a bonded body having a gold (Au) layer on the surface of the substrate.
(1) Measurement of the weight loss rate (%) of organic compounds in organic materials with increasing temperature A commercially available liquid gold (catalog number: N-15, Noritake Co., Ltd.) was dried in a container at a temperature of 60°C. This dried body was taken out and used as a sample, and thermal analysis was performed using a thermogravimetric analyzer (TG-DTA/H, product of Rigaku Corporation). Specifically, about 10 mg of the sample was heated from room temperature to 1,000°C at a rate of 1°C/min, and the thermal behavior was observed when the sample was held at 1000°C for 10 minutes.
The weight loss rate (%) of the sample with increasing temperature was calculated based on the weight of the entire sample at the start of the measurement being 100% by weight. The TG-DTA measurement results (graph) of the sample are shown in FIG.

In Fig. 2, the weight loss rate (%) at the start of the measurement is set to zero (0), and the weight loss rate of the sample with increasing temperature is shown. The weight loss of the sample represents the weight of the remaining solvent and organic compounds lost due to the increase in temperature.
As shown in Fig. 2, the weight (%) of the sample decreased with increasing temperature until the temperature reached 400°C. When the temperature exceeded 400°C, the weight (%) of the sample did not decrease. This indicates that the sample contained organic compounds until the temperature reached a certain level.

(2) Formation of metal layer (metal particle sintered body, in this case gold particle sintered body) As an organic material for forming the gold particle sintered body, commercially available water-gold liquid (catalog number: N-15, Noritake Co., Ltd.) was added with a solvent (WA oil, produced by Noritake Co., Ltd.) to prepare a diluted solution in which the water-metal solution was diluted three times.
Next, the diluted solution was applied to the surface of a tungsten (W) substrate as a base material. The amount of the diluted solution applied was adjusted so that the thickness of the gold particle sintered body (ie, the gold layer here) would be approximately 200 to 300 nm after heat treatment 1, which will be described later.
Next, the diluted solution applied to the substrate was dried at 60° C. for 1 hour to form a dry film.
The commercially available water gold solution is prepared by dissolving Au resinate obtained by reacting gold (Au) chloride and sulfurized balsam in the above solvent so that the gold (Au) content is 15% by mass. This is the prepared solution.
The dried film was heat treated (heat treatment 1). Organic compounds such as solvent and resin were removed from the water-gold liquid by heat treatment 1, and it became a sintered body of gold particles. That is, gold particle sintered bodies (hereinafter also referred to as "gold layers") of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-5 below were obtained.

Example 1-1
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 260° C. for 30 minutes to form the gold layer of Example 1-1 on the substrate surface.
Example 1-2
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 300° C. for 30 minutes to form the gold layer of Example 1-2 on the substrate surface.
Example 1-3
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 400° C. for 30 minutes to form the gold layer of Example 1-3 on the substrate surface.

Comparative example 1-1
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 240° C. for 30 minutes to form a gold layer of Comparative Example 1-1 on the substrate surface.
Comparative example 1-2
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 250° C. for 30 minutes to form a gold layer of Comparative Example 1-2 on the substrate surface.
Comparative example 1-3
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 500° C. for 30 minutes to form a gold layer of Comparative Example 1-3 on the substrate surface.
Comparative example 1-4
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 650° C. for 30 minutes to form a gold layer of Comparative Example 1-4 on the substrate surface.
Comparative example 1-5
The temperature of the dried film was raised from room temperature in the air at a rate of 10° C./min and held at 800° C. for 30 minutes to form a gold layer of Comparative Example 1-5 on the substrate surface.

Regarding each of the above-mentioned Examples and Comparative Examples, in Examples 1-1 to 1-3 and Comparative Examples 1-3 to 1-5, the metal layer after heat treatment was shining gold. That is, formation of a gold layer was confirmed. Although details will be described later, when these cross-sectional structures were observed by FE-SFM, it was observed that the gold particles were sintered with each other (see FIGS. 27 and 28). That is, it was found that the heat treatment 1 removed organic compounds such as solvents and resins contained in the water-metal solution, and a gold particle sintered body was formed as a gold layer.
On the other hand, in Comparative Examples 1-1 and 1-2, formation of a metal layer was confirmed on the substrate surface after heat treatment 1, but the metal layer (ie, gold layer) was black and dull. It is considered that in these comparative examples, the removal of the resin in the gold layer did not proceed sufficiently, and the sintering of the gold particles did not proceed.

(3) Analysis of sulfur element in gold layer The sulfur (S) element concentration in the gold layer prepared in the above Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-5 was measured using an X-ray fluorescence analyzer (XRF: Rigaku, ZSX Primus II). The results are shown in FIG.
3, it was found that the element sulfur (S) (sulfur component) was present in the gold layers of Examples 1-1 to 1-3 and Comparative Examples 1-1 and 1-2, in which the temperature in the heat treatment 1 was 450° C. or less. On the other hand, the element sulfur (S) was not detected in the metal layers of Comparative Examples 1-3 to 1-5, in which the heat treatment was performed at a temperature exceeding 450° C.
From this, it was confirmed that when the temperature of heat treatment 1 is lower than a predetermined temperature and is equal to or higher than the temperature at which most of the resin can be removed and sintering of the gold particles proceeds, a gold layer containing sulfur components can be formed.

As described above, when an organic material containing a specific organometallic compound and a sulfur component is applied to the surface of a substrate, and the substrate to which the organic material is applied is heat-treated under specific temperature conditions, a metal layer containing a metal component and a sulfur component can be formed on the substrate.

(5) Pyrolysis GC/MS analysis of gold layer Next, the gold layer of Example 1-2 was analyzed using a pyrolysis GCMS device (GCMS-QP2010 Ultra, a product of Shimadzu Corporation) to analyze the amount contained in the gold layer. The components were analyzed.
First, regarding the gold layer of Example 1-2, the gold layer was scraped off from the surface of the base material, and 2.48 mg of the gold layer was heated at 550°C in a helium gas atmosphere for instant pyrolysis, and the gold layer generated from the sample was Gas components were measured by GCMS. The heating furnace used was EGA/PY-3030D manufactured by Frontier Lab. The column used was Rtx5 (registered trademark) Amine [0.25 mmφ x 30 m F.T: 0.5 μm] manufactured by Restek, and the column temperature was raised from 40°C to 280°C at a rate of 10°C/min. It was held at The electron impact method (EI method) was used as the ionization method of the mass spectrometer.
Note that the conditions of the injection port temperature, interface temperature, carrier gas, ionization method, and scanning mass range of the GCMS apparatus are as follows.
Inlet temperature: 280℃
Interface temperature: 300℃
Carrier gas: Helium 1.8 mL/min
Ionization method: EI 70 eV
Scanning mass range: m/z 10-600

The obtained pyrolysis GCMS spectrum is shown in FIG.
Peak No. detected in FIG. MS spectra of Nos. 1 to 19 were obtained, and the corresponding compounds were estimated by referring to past library data. The results are shown in Table 1.

に示されるベンゾチオフェンであると推定された。なお、図７に、ピークＮｏ．１２のＭＳスペクトル、図８にベンゾチオフェンのライブラリデータ（ＭＳスペクトル）を示す。
ピークＮｏ.１４は、ＭＳスペクトルにおいて、分子量が１４８であること、過去のライブラリデータとの照合によって、以下の化学式：

に示される２－メチルベンゾチオフェンであると推定された。なお、図９に、ピークＮｏ．１４のＭＳスペクトル、図１０に２－メチルベンゾチオフェンのライブラリデータ（ＭＳスペクトル）を示す。 Among the above compounds, peak No. 3 was estimated to be sulfur dioxide (SO ₂ ) based on the molecular weight of 64 in the MS spectrum and comparison with past library data. In addition, in FIG. 5, peak No. FIG. 6 shows the library data (MS spectrum) of sulfur dioxide (SO ₂ ).

Peak No. 12 has a molecular weight of 134 in the MS spectrum, and by checking with past library data, it has the following chemical formula:

It was presumed to be benzothiophene shown in In addition, in FIG. 7, peak No. Figure 8 shows the library data (MS spectrum) of benzothiophene.
Peak No. 14 has a molecular weight of 148 in the MS spectrum, and by checking with past library data, it has the following chemical formula:

It was presumed to be 2-methylbenzothiophene shown in In addition, in FIG. 9, peak No. Figure 10 shows the library data (MS spectrum) of 2-methylbenzothiophene.

<Example 2: Production of joined body>
In Example 2, a joined body including a base material, a metal layer, and a noble metal sintered layer was produced.
(1) Example of manufacturing gold particles Sample 1:
50 mL of octanol (product of Fuji Film Wako Pure Chemical Industries, Ltd.) was added to 20.5 g of chloroauric acid tetrahydrate (product of Kensho Kikinzoku Kako Co., Ltd.), and the resulting solution was cooled and stirred in an ice bath.
Next, n-octylamine (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) in an amount of 5 molar equivalents relative to the gold content was added little by little to the above solution while suppressing heat generation. A complexing solution was prepared.
This complex-forming solution was subjected to a reduction treatment in which it was heated in an oil bath at 140° C. for 3 hours in an air atmosphere to reduce gold ions, thereby synthesizing gold fine particles according to this example.
Thereafter, the reaction solution was naturally cooled, industrial alcohol (manufactured by Kanka Kagaku Sangyo Products) was added to precipitate the gold particles, and the supernatant liquid was removed by decantation. After repeating this operation three times, industrial alcohol was added and centrifugation was performed at 3000 rpm for 3 minutes two or more times (here, three times) to remove the supernatant. Then, by drying at room temperature for 12 hours, a dry powder material consisting of noble metal fine particles was obtained.

Sample 2:
A dry powder material composed of fine precious metal particles was obtained using the same materials and procedures as in the production of Sample 1, except that the amount of n-octylamine was 10 molar equivalents relative to the gold content.
Sample 3:
A dry powder material consisting of fine precious metal particles was obtained using the same materials and procedures as in the production of Sample 1, except that the amount of n-octylamine was 25 molar equivalents relative to the gold content.

Sample 4:
A dry powder material composed of fine precious metal particles was obtained using the same materials and operations as in the production of Sample 1, except that 50 molar equivalents of pure water relative to the gold content were added to the chloroauric acid-octylamine complex-forming solution and a heating reaction was carried out.
Sample 5:
A dry powder material composed of fine precious metal particles was obtained using the same materials and procedures as in the production of Sample 1, except that n-butylamine was used instead of n-octylamine.
Sample 6:
A dry powder material composed of fine precious metal particles was obtained using the same materials and procedures as in the production of Sample 1, except that n-hexylamine was used instead of n-octylamine.

(2) Manufacturing sample 1-1 of gold fine particle dispersion:
Menthanol, which is a cyclic alcohol, was added as a dispersion medium to the powder material of Sample 1, and the mixture was allowed to stand for 3 hours or more. Thereafter, solvent replacement was performed by centrifugation.
Menthanol was added to the obtained wet powder so that the weight of the gold fine particles was 80 to 90% by weight of the total amount, and the mixture was mixed and dispersed using a rotation-revolution mixer to prepare a dispersion liquid (sample 1-1).

Sample 2-1:
A dispersion liquid (sample 2-1) was prepared using the same materials and operations as in the production of sample 1-1, except that the powder material of sample 2 was used.
Sample 2-2:
A dispersion liquid (sample 2-2) was prepared using the same materials and operations as in the production of sample 2-1, except that menthanol/menthol (mass ratio 80/20) mixed alcohol was used as the dispersion medium.
Sample 2-3:
A dispersion liquid (Sample 2-3) was prepared using the same materials and operations as in the production of Sample 2-1, except that menthanol/menthol (mass ratio 50/50) mixed alcohol was used as the dispersion medium.
Sample 2-4:
A dispersion liquid (Sample 2-4) was prepared using the same materials and operations as in the production of Sample 2-1, except that menthanol/cyclopentanol (mass ratio 80/20) mixed alcohol was used as the dispersion medium.
Sample 2-5:
A dispersion liquid (Sample 2-5) was prepared using the same materials and operations as in the production of Sample 2-1, except that menthanol/cycloheptanol (mass ratio 80/20) mixed alcohol was used as the dispersion medium.

Sample 3-1:
A dispersion liquid (sample 3-1) was prepared using the same materials and operations as in the production of sample 1-1, except that the powder material of sample 3 was used.
Sample 4-1:
A dispersion liquid (sample 4-1) was prepared using the same materials and operations as in the production of sample 1-1, except that the powder material of sample 4 was used.
Sample 5-1:
A dispersion liquid (sample 5-1) was prepared using the same materials and operations as in the production of sample 1-1, except that the powder material of sample 5 was used.
Sample 6-1:
A dispersion liquid (sample 6-1) was prepared using the same materials and operations as in the production of sample 1-1, except that the powder material of sample 6 was used.

(3) Physical properties of gold microparticles A field emission scanning electron microscope (FE-SEM: Hitachi High-Technologies Corporation, S-4700) was used to observe the gold microparticles in the powder material of Samples 1 to 6 (see Figures 11 to 16). Specifically, five images were randomly extracted from a 100,000x or 50,000x field of view, and the particle sizes of 40 independent particles were measured, and the average particle size (DSEM) was calculated from the particle sizes of a total of 200 particles. The results are shown in the corresponding columns of Table 2.

In addition, for the powder materials of Samples 1 to 6, samples with appropriate concentrations were obtained by ultrasonic dispersion using Zetasizer Nano ZS (a product of Malvern Panalytical) and N,N-dimethylformamide (DMF) as a dispersion medium. The sample was prepared and subjected to DLS measurement at 20°C, and the Z average particle size (DDLS) was calculated based on the general cumulant method. Here, if DDLS/DSEM was 2 or less, it was determined that there was no aggregation. The results are shown in the relevant column of Table 2.

As shown in Table 2, it was confirmed that the gold fine particles of the powder material of each sample had a DDLS/DSEM of 2 or less, and had good dispersibility. Furthermore, each sample had a Z average particle size (DDLS) of 150 nm or less, confirming that it is a good powder material that contributes to miniaturization of electronic components and thinning of electrodes.
Furthermore, as shown in the relevant column of Table 2, in the powder materials according to each example, a large exothermic peak (derived from oxidation) observed in alkylamine particles at 200°C or higher was detected in TG-DTA. There wasn't. This means that the organic molecules present on the surface of the gold fine particles of each sample are converted from alkylamines to imine compounds (alkylimines: see the above structural formula) in the reaction system in which the gold fine particles are synthesized. This shows that almost no amine added to the system remains.

(4) Detection of Imine Compounds Each gold fine particle dry powder material was analyzed using a pyrolysis GCMS device (Shimadzu Corporation, GCMS-QP2010 Ultra).
Specifically, about 20 mg of dry gold fine particle powder was heated at 300°C for 18 seconds to perform pyrolysis, and the gas components generated from the sample were measured by GCMS. The column used was Ultra ALLOY±5 (UA5-30M-0.25F) manufactured by Frontier Labs, and the column oven temperature was raised from 40°C to 320°C at a rate of 10°C/min and held at 320°C for 32 minutes. The ionization method used by the mass spectrometer was the electron impact method (EI method).
The pyrolysis GCMS spectra obtained for Samples 1 to 6 are shown in Figures 17 to 22, respectively.
Moreover, the MS spectrum of the peak of imine compound A detected in Samples 1 to 4 (peak ■ in the corresponding pyrolysis GCMS spectrum) is shown in Figure 23. Furthermore, the MS spectrum of the peak of imine compound B detected in Sample 5 (peak ■ in the corresponding pyrolysis GCMS spectrum) is shown in Figure 24. Furthermore, the MS spectrum of the peak of imine compound C detected in Sample 6 (peak ■ in the corresponding pyrolysis GCMS spectrum) is shown in Figure 25.

The above-mentioned imine compounds A, B and C were identified as follows.
Imine compound A
Structural formula: ^R0R1C =N-( ^CH2 ₎ ^-R2
wherein R ⁰ is hydrogen, and R ¹ and R ² are each CH ₃ (CH ₂ ) ₆ .
Imine compound B
Structural formula: ^R0R1C =N-( ^CH2 ₎ ^-R2
wherein R ⁰ is hydrogen, and R ¹ and R ² are each CH ₃ (CH ₂ ) ₂ .
Imine compound C
Structural formula: ^R0R1C =N-( ^CH2 ₎ ^-R2
wherein R ⁰ is hydrogen, and R ¹ and R ² are each CH ₃ (CH ₂ ) ₄ .

The identification of imine compounds A, B and C as described above is due to the following analytical steps.
That is, the amine peak (○) seen in each spectrum and the imine compound B peak (■) seen in the spectrum of sample 5 were assigned by performing a GCMS library search (see FIG. 26).
On the other hand, since there was no data on imine compounds A and C in the library, they were assigned based on the following considerations.
In each MS spectrum of imine compounds A, B, and C (see Figures 23 to 25), values considered to be derived from fragments detected on the low molecular weight side such as 56 (57), 70, 84, 98 (99), and 112 are found. Since there is almost no difference, it is inferred that they have similar skeletons. Therefore, it can be seen that, like B, which is an imine compound, A and C have an extremely high possibility of having an imine skeleton.
In addition, in the MS spectrum of imine compound B, since molecular weight 84 is detected most frequently, it is thought that cleavage (fragmentation) occurs mainly at the position shown in the structural formula below. Note that the numerical value attached to the structural formula corresponds to the molecular weight of the fragment ion after cleavage.

Therefore, it is presumed that compounds A and C, which are thought to have similar skeletons, also cleave mainly at the same position. In the MS spectrum of compound B, it is determined that the molecular weights of 57, 70, 99, etc. are derived from fragment peaks from cleavage at positions other than those mentioned above, and 126 is derived from the molecular ion peak.
From the above considerations and the components present during synthesis, the structures of compounds A and C were inferred. First, as shown in the structural formula below, the structure of compound A was determined based on the fact that the most detected molecular weight of 140 resulting from cleavage at the same position as compound B was the molecular weight of 168, 196, etc., which are thought to be the molecular weights of fragment peaks resulting from cleavage at other positions, and 238, which is thought to be the molecular weight of a molecular ion peak, was detected.

Next, for compound C, as shown in the structural formula below, the molecular weight of 112, resulting from cleavage at the same position as compound B, was most frequently detected, and 140, 168, etc., which are thought to be the molecular weights of fragment peaks resulting from cleavage at other positions, and 184, which is thought to be the molecular weight of the molecular ion peak, were also detected, so the structure was determined.

As shown in the corresponding column of Table 2, it was confirmed that the desired imine compound (here, alkylimine) was produced on the surface of the gold fine particles in each of the above samples. Further, as is clear from the thermal decomposition GCMS spectra of each example, it is recognized that the amount of imine compounds produced is large compared to the remaining amount of amine compounds (see A/I ratio described below).

Next, the area value of each peak was calculated from the pyrolysis GCMS spectrum using analysis software. The amine/imine ratio (A/I ratio) was then determined from the area values of the imine compound and amine compound (the sum of the peak areas in the case of multiple peaks). The results are shown in Table 3.

As shown in Table 3, the A/I ratio of the gold particles (powder) of each of the above samples was 1 or less (specifically 0.6 or less), indicating that the conversion from an amine compound to an imine compound It was recognized that this was carried out with high efficiency.

(5) Performance evaluation of gold particle dispersion First, the paste-like dispersion of each sample used here was evaluated as follows: those with a rough and matte appearance and those in which the liquid and the particles were separated and film formation was impossible were rated as ×, and those without roughness and with a metallic luster were rated as ○. The corresponding column in Table 4 shows ○ and ×. In other words, the paste-like dispersion of each sample was rated as ○.

A gold sintered layer was formed using the dispersion liquid of each sample as a material, and performance evaluation was performed.
As described above, a paste dispersion of each sample prepared so that the weight of gold fine particles was 80 to 90% by weight of the total amount was applied to a glass substrate. Specifically, each dispersion was applied onto a metal mask measuring 1 cm x 1 cm x 100 μm and squeezed with a rubber squeegee to form a film of each dispersion in a predetermined shape. Then, after drying at 60°C for 1 hour, heat treatment (heat treatment 2) was performed at 250°C or 300°C for 30 minutes to form a gold sintered layer in a predetermined shape.
The sheet resistance value of the obtained gold sintered layer was measured using a commercially available resistivity meter, Loresta GP (MCP-T610, manufactured by Mitsubishi Chemical Analytech Corporation). Further, the film thickness was measured using a thickness measuring device (TH-102 manufactured by Tester Sangyo Co., Ltd.). The volume resistivity was calculated as the product of the obtained sheet resistance value and film thickness. The results are shown in Table 4.
Furthermore, the ion milling polished surface was observed using FESEM. Specifically, from the 10,000x FESEM observation image (see Figures 11 to 16), the area of the black void part was determined using the image analysis software "Image Pro" manufactured by Media Cybernetics, and the density (%) = 1 - It was calculated as (void area/total area)%. The results are shown in the relevant column of Table 4.

As is clear from the results shown in Table 4, the sintered layer (i.e., layered sintered body) made of gold fine particles of each of the above samples, which have an imine compound on the surface at a suitable A/I ratio (see Table 3), has high density, and as a result, it was confirmed that a conductive film with low volume resistivity and good conductivity can be formed. It was also confirmed that a good precious metal sintered layer can be obtained at a low heat treatment temperature of 250 to 300°C.

(6) Formation of gold sintered layer in joined body Example 2-1:
Menthanol, which is a cyclic alcohol, was added as a dispersion medium to the powder material of Sample 2, and the mixture was allowed to stand for 3 hours or more. Thereafter, solvent replacement was performed by centrifugation.
Menthanol was added to the obtained wet powder so that the weight of the gold particles was 70 to 80% by weight of the total amount, and the mixture was mixed and dispersed using a rotation-revolution mixer to prepare a dispersion liquid.
The above dispersion was applied onto the gold layer of Example 1-2. Specifically, each dispersion was applied onto a metal mask measuring 1 cm x 1 cm x 100 μm and squeezed with a rubber squeegee to form a film of each dispersion in a predetermined shape. Thereafter, after drying at 60°C for 1 hour, the temperature was raised in the air at a rate of 10°C/min, and heat treatment was performed at 250°C for 30 minutes (heat treatment 3) to form a gold sintered layer in a predetermined shape. . In this way, the joined body of Example 2-1 was produced.

Example 2-2:
A gold sintered layer was formed in the same manner as in Example 2-1, except that the temperature in heat treatment 3 was 300° C., to produce a joint body of Example 2-2.
Example 2-3:
In the same manner as in Example 1(2) above, a gold solution was applied to the surface of a tungsten substrate, and a dry film was formed on the surface of the substrate. This was heat-treated at 350° C. to form a gold layer. A joint body of Example 2-3 was produced in the same manner as in Example 2-1, except that the gold fine particle dispersion was applied onto this gold layer.
Example 2-4:
A bonded body of Example 2-4 was produced in the same manner as in Example 2-2, except that the gold particle dispersion was applied onto the gold layer formed in Example 2-3.
Example 2-5:
A gold solution was applied to the surface of a glass substrate in the same manner as in Example 1(2) above, and a dry film was formed on the surface of the substrate. This was heat-treated at 300° C. to form a gold layer. A bonded body of Example 2-5 was produced in the same manner as in Example 2-1, except that the gold particle dispersion was applied onto this gold layer.

Comparative example 2-1:
A bonded body of Comparative Example 2-1 was prepared in the same manner as in Example 2-1 except that the gold fine particle dispersion was directly coated on a tungsten substrate on which no metal layer was formed.
Comparative example 2-2:
A water-metal solution was applied to the surface of a tungsten substrate in the same manner as in Example 1 (2) above, and this was heat-treated at 500° C. to form a gold layer. A bonded body of Comparative Example 2-2 was prepared in the same manner as in Example 2-1 except that the gold fine particle dispersion was coated on this gold layer.

(2) Observation of the cross-sectional structure of the bonded bodies The cross-sections of the bonded bodies of each of the above examples and comparative examples were polished by ion milling, and the cross-sections were polished using a field emission scanning electron microscope (FE-SEM: manufactured by Hitachi High-Technologies Corporation, S- 8230) to observe the substrate-gold layer interface (junction) and the gold layer-gold sintered layer interface (junction).
Images of the interface of the bonded body of Example 2-2 are shown in FIGS. 27 and 28. As shown in FIGS. 27 and 28, the bonded body of Example 2-2 has a structure in which a base material, a gold layer, and a sintered gold layer are stacked on top in this order from the bottom in the figure. observed. The gold layer was observed to consist of sintered gold particles (ie, gold particle sinter). When the gold layer and the gold sintered layer were observed here, it was found that the voids in the gold sintered layer were smaller and fewer in number than the voids in the gold layer. That is, it was confirmed that the density of the gold sintered layer was higher than that of the gold layer.
Although specific illustrations are omitted, laminated structures as shown in FIGS. 27 and 28 were also observed in each Example and Comparative Example 2-2. Regarding Comparative Example 2-1, a structure in which the base material and the gold sintered layer were laminated was observed.

The presence or absence of peeling was also visually observed at the substrate-gold layer interface and the gold layer-sintered gold layer interface. The results are shown in Table 5.
As shown in Table 5, in Comparative Example 2-2, the adhesion between the gold layer and the sintered gold layer at the interface between the two layers was low, and the gold sintered layer was judged to be "peeled off" by visual observation.

(3) Performance evaluation of gold layer A test was conducted to evaluate the adhesion (bonding strength) of the gold sintered layer to the base material (gold layer) for the joined bodies of each of the above examples and comparative examples.
Specifically, after applying cellophane tape (manufactured by Nichiban Co., Ltd., CT-18) to the surface of the base material and gold sintered layer of each bonded body by pressing it well with your fingers, a tensile tape was applied from the surface of the base material. It was peeled off in a 90° direction using a testing machine. At this time, the presence or absence of peeling of the gold sintered layer by the cellophane tape was visually observed. The results are shown in the appropriate column of Table 5. For Comparative Example 2-2, peeling of the gold sintered layer was observed under visual observation as described above, so a peeling test was not conducted.

As shown in Table 5, in each Example, neither the gold sintered layer nor the gold layer peeled off in the peel test. On the other hand, in Comparative Example 2-1, the gold sintered layer was peeled off from the base material in the peel test.

From the above XRF analysis, it has been confirmed that the gold layer contains sulfur (S) element if the temperature in heat treatment 1 is 450° C. or less. Therefore, in Examples 2-1 to 2-5 in which the gold layer was produced at a temperature of 450° C. or less in heat treatment 1, the gold layer contains sulfur (S) element.
In Examples 2-1 to 2-5, when the paste material for producing the gold sintered layer is applied to the surface of the gold layer and heat-treated (Heat Treatment 3), the gold particles in the paste material can interact with the sulfur components contained in the gold layer earlier than the sintering of the gold particles with each other. This can promote the reaction and sintering of the gold particles with the metal components (here, the gold components) in the gold layer. This is thought to have improved the adhesion (i.e., the bonding strength) between the gold sintered layer and the gold layer.
On the other hand, in Comparative Example 2-2, since the gold layer was produced at a temperature exceeding 450°C in Heat Treatment 1, it is believed that the gold layer does not contain sulfur (S) elements. Therefore, neither the reactivity nor the sinterability between the gold fine particles in the paste material and the gold layer was improved. In Heat Treatment 3, the gold fine particles sinter with each other early, so the adhesion (i.e., bonding strength) between the gold sintered layer and the gold layer is low, and it is believed that peeling was confirmed by the peel test.

As described above, according to the metal particle sintered body and bonded body disclosed herein, it is possible to provide a bonded body in which the bonding strength between the noble metal sintered layer (sintered body) and the base material is significantly improved. The conjugate disclosed herein can be used for various purposes.

10 Metal layer (metal particle sintered body)
20 Precious metal sintered layer 30 Base material 100 Joined body Z direction

Claims (17)

A sintered body of metal particles,
Contains a metal component and a sulfur component,
A metal particle sintered body characterized in that a compound containing sulfur (S) element is detected as a thermal decomposition product. The metal particle sintered body according to claim 1, wherein the sulfur component is a sulfur-containing organic compound. The metal particle sintered body according to claim 1 or 2, wherein the compound containing sulfur (S) element includes at least one of benzothiophene and 2-methylbenzothiophene. The metal particle sintered body according to any one of claims 1 to 3, wherein the metal component contains a noble metal element as a main constituent element. The metal particle sintered body according to claim 4, wherein the precious metal element is gold (Au). A joint body including a metal layer made of a metal particle sintered body and a precious metal sintered layer containing a precious metal element as a main constituent metal element,
The noble metal sintered layer is formed on at least a part of a surface of the metal layer,
At least a portion of the joint between the metal layer and the sintered precious metal layer is sintered. The bonded body according to claim 6, wherein the density of the precious metal sintered layer is higher than the density of the metal layer. The joined body according to claim 6 or 7, wherein the metal layer is mainly composed of gold (Au). The joint body according to any one of claims 6 to 8, wherein the metal layer is composed of the metal particle sintered body according to any one of claims 1 to 5. The joined body according to any one of claims 6 to 9, wherein the noble metal sintered layer is mainly composed of gold (Au). The joined body according to any one of claims 6 to 10, further comprising a base material, and the metal layer is formed on at least a portion of the surface of the base material. A joined body comprising a base material and a metal layer,
The metal layer is formed on at least a portion of the surface of the base material,
A joined body, wherein the metal layer is constituted by the metal particle sintered body according to any one of claims 1 to 5. A substrate;
a metal layer disposed on at least a portion of a surface of the substrate;
A precious metal sintered layer containing a precious metal element as a main constituent metal element and provided on a surface of the metal layer;
A method for producing a bonded body comprising the steps of:
Applying an organic material containing a predetermined organometallic compound and a sulfur component to a surface of the substrate;
heat-treating the substrate to which the organic material has been applied, to form a metal layer containing a metal component and a sulfur component on the substrate;
disposing precious metal fine particles containing a precious metal as a main constituent metallic element on a surface of the metal layer; and
sintering the noble metal fine particles to form a noble metal sintered layer;
A method for producing a conjugate comprising the steps of: The manufacturing method according to claim 13, wherein the temperature of the heat treatment is 450°C or less. The method according to claim 13 or 14, wherein the noble metal particles hold at least one of an amine compound and an imine compound on their surfaces. The manufacturing method according to any one of claims 13 to 15, wherein the main constituent metal element of the noble metal microparticles is gold (Au). The manufacturing method according to claim 16, wherein the sintering temperature is 300°C or less.

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