JP2016028823A - Sintering joint material and joint method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sintering joint material which does not need to be processed under a reduction atmosphere such as hydrogen and attains high joint strengh at a relatively low temperature.SOLUTION: A sintering joint material includes copper nitride particles.SELECTED DRAWING: None

Description

  The present invention relates to a sinterable bonding material and a bonding method using the same.

  Many semiconductor devices have a structure in which a semiconductor element is bonded on a circuit layer made of a metal member. When joining electronic components such as semiconductor elements on a circuit layer, a method using a solder material is widely used. However, the semiconductor device itself is improved in the engine room of an automobile by improving the heat resistance of the semiconductor element itself. As a result, it is often used in a high-temperature environment such as, and heat resistance is required for the bonding agent. However, when an electronic component such as a semiconductor element and a circuit layer are joined using a solder material, if this is used in a high temperature environment, a part of the solder melts, and the electronic component such as a semiconductor element and a circuit It has become a problem that the bonding reliability with the layer is lowered.

  Therefore, as an alternative to the solder material, a metal oxide paste containing metal particles such as silver or copper, or metal oxide particles such as gold or silver and a reducing agent, having heat resistance, high thermal conductivity and conductivity. A technique for joining an electronic component such as a semiconductor element to a circuit layer has been proposed. In the metal oxide paste containing the metal oxide particles and the reducing agent, the metal particles generated when the metal oxide particles are reduced by the reducing agent sinter to form a bonding layer made of a conductive fired body. An electronic component such as a semiconductor element is bonded to the circuit layer through the bonding layer.

  For example, Japanese Patent Application Laid-Open No. 2013-182901 (Patent Document 1) includes a silver oxide particle, a reducing agent, and an activator that removes an oxide film of a metal member. There have been proposed a bonding material capable of improving the bonding reliability, a power module using the bonding material, and a method for manufacturing the power module. However, in the method described in Patent Document 1, there is a problem that silver used for the bonding material is likely to cause a short circuit due to ion migration, and silver is expensive in terms of cost.

  As a method for suppressing the ion migration, Japanese Patent Application Laid-Open No. 2013-91835 (Patent Document 2) discloses a liquid or paste containing copper nanoparticles having a particle diameter of 1000 nm or less, and the number-based particle diameter of copper nanoparticles. There are at least one particle size peak in the distribution in the region where the particle size is 1 to 35 nm and in the region where the particle size is greater than 35 nm and less than or equal to 1000 nm, and the copper nanoparticles are single particles (primary particles) and single particles. A sinterable bonding material including secondary particles that are a fusion of one particle has been proposed. In the method described in Patent Document 2, both oxidation resistance and low-temperature bondability are thereby achieved, but the compatibility between oxidation resistance and low-temperature bondability is not always sufficient, and a dangerous reducing atmosphere such as hydrogen There was a problem that had to be handled below.

JP 2013-182901 A JP2013-91835A

  The present invention has been made in view of the above-described problems of the prior art, and does not need to be treated in a reducing atmosphere such as hydrogen, and a sinterable bonding material capable of obtaining a high bonding strength at a relatively low temperature. It is another object of the present invention to provide a bonding method using the same.

  As a result of intensive studies to achieve the above object, the present inventors need to perform treatment under a reducing atmosphere such as hydrogen by using a sinterable bonding material containing copper nitride particles as a bonding material. Thus, the inventors have found that sintering can be performed at a relatively low temperature and that a high joint strength can be obtained, and the present invention has been completed.

  That is, the sinterable bonding material of the present invention is characterized by containing copper nitride particles.

  In the sinterable bonding material of the present invention, it is preferable that an average particle diameter of primary particles of the copper nitride particles is 1 nm to 5 μm.

  Moreover, in the sinterable joining material of this invention, it is preferable that the decomposition temperature of the said copper nitride particle is 150-500 degreeC.

  Furthermore, in the sinterable bonding material of the present invention, the content of the copper nitride particles is preferably in the range of 60 to 95% by mass with respect to 100% by mass of the sinterable bonding material.

  Further, in the sinterable bonding material of the present invention, the sinterable bonding material further contains a dispersion medium, and the dispersion medium contains esters, alcohols, glycol ethers, carboxylic acids, and aromatic hydrocarbons. It is preferably at least one selected from the group consisting of

  The joining method of the present invention is a method of joining a metal member and a joined body via a joined surface, and between the joined surface of the metal member and the joined surface of the joined body and / or Heat treatment is performed in a state where the sinterable bonding material of the present invention is disposed on the outer edge portions of both bonded surfaces, and the sinterable bonding material is sintered to bond the metal member and the bonded object. It is a characteristic method.

  In the joining method of this invention, it is preferable that the process temperature in the said heat processing is 150-500 degreeC.

  Although the reason why the above object is achieved by the sinterable bonding material of the present invention and the bonding method using the same is not certain, the present inventors speculate as follows.

  That is, first, the sinterable bonding material of the present invention contains copper nitride particles. The copper nitride particles are hardly oxidized, are stable in an oxygen atmosphere, and can be sintered at a lower temperature. By using such a sinterable bonding material containing copper nitride particles, it is not necessary to treat under a reducing atmosphere such as hydrogen, and a high bonding strength can be expressed at a relatively low sintering temperature. The present inventors speculate that this is the case.

  Further, in the joining method of the present invention, when such a sinterable joining material containing copper nitride particles is used as a joining material for joining a metal member and an object to be joined, the contained copper nitride particles are resistant to oxidation. The inventors of the present invention believe that the bonding is possible by a safe method without using dangerous gas atmosphere conditions such as hydrogen, and that sintering is possible at a low temperature due to the presence of copper nitride particles. Guess.

  According to the present invention, it is possible to provide a sinterable bonding material that does not require treatment in a reducing atmosphere such as hydrogen and can obtain a high bonding strength at a relatively low temperature, and a bonding method using the same. It becomes.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

[Sintering bonding materials]
First, the sinterable bonding material of the present invention will be described. That is, the sinterable bonding material of the present invention is characterized by containing copper nitride particles.

  Such a sinterable bonding material of the present invention can be suitably used as a bonding material used when a metal member and an object to be bonded are bonded. The metal member may be a metal member having conductivity, and examples thereof include circuit layers such as electrodes and wirings of electronic components such as semiconductor devices. Moreover, the metal of the metal member is not particularly limited, and examples thereof include copper, silver, and gold. Although the to-be-joined body used for this invention will not be specifically limited if it is an electronic member, For example, a semiconductor element etc. are mentioned.

The “copper nitride” constituting the copper nitride particles in the sinterable bonding material of the present invention is a compound that does not substantially contain copper that has not been nitrided. Specifically, in crystal analysis by X-ray diffraction, It refers to a compound in which a peak derived from copper nitride (Cu ₃ N) is detected and a peak derived from metal is not detected. Although it does not contain copper substantially, it means that copper content is 1 mass% or less with respect to a copper nitride particle. Such nitrogen copper particles may contain, in addition to the copper nitride, copper that is not partially nitrided, an amorphous component, or the like within a range that does not impair the effects of the present invention.

  Further, the copper nitride particles in the sinterable bonding material of the present invention are not particularly limited, but the average particle size of the primary particles of the copper nitride particles is preferably 1 nm to 5 μm, and more preferably 2 nm to 1 μm. preferable. If the average particle size of the primary particles is less than the lower limit, the production of copper nitride particles tends to be difficult, whereas if the average particle size exceeds the upper limit, the handleability of the sinterable bonding material tends to deteriorate. Moreover, in this invention, the average particle diameter of the primary particle of copper nitride particles is calculated | required by transmission electron microscope (TEM) observation or scanning electron microscope (SEM) observation, etc., and about each of arbitrary 50 or more copper nitride particles The particle size (diameter) of the particles is measured, and they are obtained by arithmetic averaging. In the observation photograph (figure), when the shape of the copper nitride particles is not a perfect circle, the diameter is measured as the maximum circumscribed circle diameter of the cross section of the particles.

  Further, the decomposition temperature of the copper nitride particles according to the present invention is preferably 150 to 500 ° C, and more preferably 150 to 450 ° C. If the decomposition temperature is less than the lower limit, it tends to be difficult to produce copper nitride particles. On the other hand, if the decomposition temperature exceeds the upper limit, sintering of the sinterable bonding material tends to be difficult. The decomposition temperature is obtained by measuring the temperature of the inflection point of mass reduction in differential thermal balance analysis (normal pressure).

  The form of the copper nitride particles is not particularly limited, and examples thereof include a spherical shape, a square shape, and a needle shape. Such copper nitride particles used in the present invention are commercially available or can be obtained by production by a known technique. For example, such copper nitride particles can be produced by a method of baking copper oxide or copper fluoride in ammonia, a method of heating copper acetate or the like while blowing ammonia in alcohol, and the like.

  In general, when the particle size of a metal particle is reduced and the specific surface area is increased, the surface free energy per unit volume is increased, and the activity of the surface of the metal particle is increased. For this reason, for example, if copper nitride fine particles having a primary particle size of 1 μm or less are used, it can be decomposed into metallic copper and nitrogen at a low temperature, and as a result, bonding by firing at a low temperature becomes possible. Therefore, the joined body such as an electronic member is not easily damaged by heat, for example, melted or deformed. On the other hand, the particle size of the metal particles is reduced and the specific surface area is increased, so that the metal particles are easily oxidized, and the copper metal is easily oxidized to copper oxide, whereas the copper nitride has oxidation resistance and is stable. It is known that there is. Therefore, by using copper nitride as the sinterable bonding material, it is not necessary to strictly limit the atmospheric gas, and the bonding process of the sinterable bonding material can be simplified.

  Furthermore, the copper nitride particles according to the present invention are preferably dispersed in a liquid or paste-like dispersion medium from the viewpoint of handleability of the sinterable bonding material, and the content of the copper nitride particles is From the viewpoint of handleability of the sinterable bonding material, it is preferably in the range of 60 to 95% by mass and more preferably in the range of 65 to 95% by mass with respect to 100% by mass of the sinterable bonding material. preferable.

  The dispersion medium used in such a sinterable bonding material is not particularly limited as long as it is a liquid or paste as long as copper nitride is dispersed and does not remain during sintering. Hydrocarbon compounds such as ketones, esters, alcohols, glycol ethers, carboxylic acids, aromatic hydrocarbons, aliphatic hydrocarbons, petroleum hydrocarbons, and waxes. Examples of water include ion exchange water and distilled water. Examples of ketones include ketones having 3 to 20 carbon atoms such as isophorone and diisobutyl ketone. Examples of the esters include esters having 3 to 20 carbon atoms, such as methyl acetate, butyl acetate, isobutyl acetate, propyl acetate, ethylene glycol monobutyl ether acetate, and diethylene glycol monobutyl ether acetate. Examples of alcohols include linear or branched saturated alcohols having 1 to 22 carbon atoms, linear or branched unsaturated alcohols having 3 to 22 carbon atoms, and cyclic alcohols having 6 to 22 carbon atoms. , Methanol, ethanol, propanol, secondary butyl alcohol, octanol, nonanol, decanol, phenol, terpineol and the like. Examples of glycol ethers include glycol ethers having 3 to 20 carbon atoms, such as ethylene glycol monomethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and tripropylene glycol monomethyl ether. Examples of carboxylic acids include carboxylic acids having 1 to 10 carbon atoms such as formic acid, acetic acid, and lactic acid. Examples of the aromatic hydrocarbons include aromatic hydrocarbons having 6 to 20 carbon atoms, such as benzene, toluene, xylene, and styrene. Examples of the aliphatic hydrocarbons include saturated and unsaturated aliphatic hydrocarbons having 3 to 18 carbon atoms, such as tridecane, tetradecane, pentadecane, and hexadecane. Examples of petroleum hydrocarbons include mineral spirit, gasoline, coal tar naphtha, petroleum ether, petroleum naphtha, petroleum benzine, and turpentine oil. Examples of waxes include plant-based waxes (such as goby wax and urushi wax), animal-based waxes (such as beeswax and whale wax), mineral-based waxes (such as montan wax), petroleum-based waxes (such as paraffin wax), and synthetic waxes. Is mentioned.

  In such a sinterable bonding material of the present invention, the sinterable bonding material further contains a dispersion medium, and the dispersion medium contains esters, alcohols, glycol ethers, carboxylic acids and aromatics. It is preferably at least one selected from the group consisting of group hydrocarbons. Use of such a dispersion medium tends to facilitate the dispersion of copper nitride.

  In addition, the content of the dispersion medium in the sinterable bonding material of the present invention is not particularly limited, but from the viewpoint of handling of the sinterable bonding material, the sinterable bonding material is 100% by mass. It is preferable that it exists in the range of 5-40 mass% with respect to it, and it is more preferable that it exists in the range of 5-35 mass%.

  Moreover, in the sinterable bonding material of the present invention, a dispersant can be further blended in order to improve the dispersibility of the copper nitride particles. As the dispersant, those having little residue at the time of sintering joining and being hardly affected are preferable, and examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, a chelating agent, and a water-soluble polymer.

  Anionic surfactants include soap, alkylbenzene sulfonate, higher alcohol sulfate, polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid ester, α-olefin sulfonate, alkane sulfonate, monoalkyl phosphate Examples include ester salts.

Examples of the cationic surfactant include alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium salt, alkyl dimethyl benzyl ammonium salt and the like.
Nonionic surfactants include higher alcohol alkylene oxide adducts, alkylphenol alkylene oxide adducts, fatty acid alkylene oxide adducts, polyhydric alcohol fatty acid ester alkylene oxide adducts, higher alkylamine alkylene oxide adducts, fatty acid amide alkylene oxide adducts. And polyalkylene glycol types such as polyoxypropylene alkylene oxide adducts; and polyhydric alcohol types such as glycerol fatty acid esters, pentaerythritol fatty acid esters, sorbitol fatty acid esters, and sucrose fatty acid esters. The higher alcohols mentioned here are usually straight or branched unsaturated or saturated higher alcohols having 8 to 22 carbon atoms, and the alkylphenols are usually straight or branched unsaturated or saturated alkyl phenols having 6 to 22 carbon atoms. Yes, the fatty acid is usually an unsaturated or saturated fatty acid having 10 to 22 carbon atoms, the polyhydric alcohol is usually a polyhydric alcohol having 3 to 12 carbon atoms, and the higher alkylamine is usually a straight chain having 8 to 22 carbon atoms. Or a branched, unsaturated or saturated higher alkyl amine.

  Examples of the chelating agent include citric acid and ethylenediaminetetraacetic acid. Examples of the water-soluble polymer include polyvinyl pyrrolidone, polyacrylic acid, polyvinyl alcohol, and polyethylene glycol.

  The blending amount of such a dispersant is preferably 60 parts by mass or less with respect to 100 parts by mass of the copper nitride particles from the viewpoint of the dispersibility of copper nitride and the persistence of the dispersant.

  Furthermore, resin, metal filler, flux, etc. can be mix | blended with the sinterable joining material of this invention in the range which does not impair the effect of this invention.

  Next, the manufacturing method of the sinterable joining material of this invention is demonstrated. Although the manufacturing method of a sinterable joining material is not specifically limited, For example, the method of stirring and mixing the said copper nitride particle and the said dispersion medium is mentioned. A mixer used in the stirring and mixing is appropriately selected and used. For example, a mixer such as a homomixer, an agitator, a disper, a planetary mixer, an azimuthal mixer, a universal mixer, or an attritor can be used. These can select 1 type, or 2 or more types of methods.

[Joint method]
Next, the joining method of the present invention using the sinterable joining material of the present invention will be described. That is, the bonding method of the present invention is a method of bonding a metal member and a bonded body via a bonded surface, between the bonded surface of the metal member and the bonded surface of the bonded member, and / Or heat treatment in a state where the sinterable bonding material of the present invention is disposed on the outer edge portions of both surfaces to be bonded, and sintering the sinterable bonding material to bond the metal member and the object to be bonded. It is characterized by damaging. Such a joining method of the present invention can be suitably used when joining a metal member and an object to be joined.

In such a bonding method of the present invention, the sinterable bonding material of the present invention is provided between the bonded surface of the metal member and the bonded surface of the bonded body and / or at the outer edge of both bonded surfaces. The following states can exist as the state where the is arranged.
(1) A state in which the sinterable bonding material of the present invention is disposed only between the bonded surface of the metal member and the bonded surface of the bonded body.
(2) The state in which the sinterable bonding material of the present invention is disposed only on the outer edge portions of both the bonded surfaces of the metal member and the bonded surface of the bonded body.
(3) A state in which the sinterable bonding material of the present invention is disposed between the bonded surface of the metal member and the bonded surface of the bonded body and on the outer edge of both bonded surfaces.

  In addition, as a method of arranging the sinterable bonding material, paste is ejected from a fine nozzle by an ink jet method, and applied, adhered, injected, coated, or filled to the electrode and / or the connection part of the electronic component on the substrate. Method, method of applying, adhering, injecting, coating or filling only the necessary part using a metal mask or mesh-shaped mask with an opening to be arranged, applying, adhering, injecting, coating or applying to the required part using a dispenser Examples of the method include filling. These arrangement methods can be combined according to the area and shape of the electrodes to be joined.

  The amount of the sinterable bonding material may be adjusted according to the size of the electronic component to be bonded, the adhesive strength, and the like, and is not particularly limited.

  Furthermore, in the joining method of this invention, it is preferable that the process temperature in the said heat processing is 150-500 degreeC. If the decomposition temperature is less than the lower limit, the decomposition of the copper nitride particles tends to be difficult. On the other hand, if the decomposition temperature is higher than the upper limit, the joined body such as an electronic member is easily damaged by heat, for example, melting, deformation, etc. Tend to be.

  Moreover, the atmosphere conditions in the joining method of the said metal member and a to-be-joined body are not specifically limited, For example, air atmosphere, an inert gas, etc. are mentioned. From the viewpoint of preventing oxidation of the circuit layer or the like, an inert gas atmosphere such as nitrogen gas, argon gas, or helium gas is preferable.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
250 μL of nonanol was added to 1 g of copper nitride powder (particles) (manufactured by Santa Cruz Biotechnology, Inc., “SC-268769”, average particle size of primary particles 1 μm), and a rotating / revolving mixer (manufactured by Sinky Corporation, “ SR-500 ") and stirred at 2000 rpm for 100 seconds to produce a sinterable bonding material. This sinterable bonding material was applied to a surface of a copper plate (diameter 10 mm, thickness 3 mm) to a thickness of 0.2 mm in a 5 mm diameter region using a mask. After a copper disk (diameter 5 mm, thickness 2 mm) was placed on the paste film, the copper plate and copper were pressed from the top of the copper disk at 10 MPa for 10 minutes under a temperature condition of 450 ° C. in a nitrogen gas atmosphere. The discs were joined to produce a joint strength measurement test piece. Three test pieces were prepared. In addition, as the said copper disc, what was washed with distilled water after degreasing previously using acetone and acid-washing using 5% hydrochloric acid liquid was used.

<Joint strength measurement test>
The bonding strength of the test piece was determined by measuring the maximum load at break by applying a load at a shear rate of 1 mm / min and room temperature in the shearing direction of the joint between the copper plate and the copper disc of the test piece. This maximum load was divided by the joint area (diameter 5 mm) to obtain the joint strength (shear strength) (note that the joint strength is JIS Z 3198-5 “Lead-free solder test method—Part 5: It can be measured according to “Tensile and Shear Test Method” (2003)). For the sinterable bonding material, the bonding strength of three test pieces was measured, and the average value was determined. The results are shown in Table 1.

<Decomposition temperature measurement test>
The decomposition temperature of the copper nitride powder used in Example 1 was measured using a differential thermothermal weight simultaneous measurement apparatus (manufactured by Shimadzu Corporation, “DTG-50”) under the following conditions.
〔Measurement condition〕
Atmosphere: Nitrogen gas (nitrogen gas flow rate: 100 ml / min)
Temperature rising temperature: 10 ° C / min
Sample amount: 3mg
Sample container: platinum cell Table 1 shows the results obtained by such a decomposition temperature measurement test.

(Comparative Example 1)
Comparative bonding material in the same manner as in Example 1 except that 1 g of copper (Cu) powder (“CUE08PB”, average particle diameter of primary particles: 1 μm) manufactured by High Purity Chemical Laboratory Co., Ltd. was used instead of copper nitride powder. Was made. About the obtained comparative bonding material, the bonding strength measurement test and the decomposition temperature measurement test were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
For comparison in the same manner as in Example 1 except that 1 g of copper (Cu) nanopowder (manufactured by Iritech, “NM-0016-HP”, average particle size of primary particles 25 nm) was used instead of copper nitride powder. A joining material was produced. About the obtained comparative bonding material, the bonding strength measurement test and the decomposition temperature measurement test were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
Comparative joining in the same manner as in Example 1 except that 1 g of copper oxide (CuO) powder (“CUO12PB”, average particle diameter of primary particles 1 μm) manufactured by High Purity Chemical Laboratory Co., Ltd. was used instead of copper nitride powder. The material was made. About the obtained comparative bonding material, the bonding strength measurement test and the decomposition temperature measurement test were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
Comparative bonding in the same manner as in Example 1 except that 1 g of copper oxide (CuO) nanopowder (manufactured by Sigma-Aldrich, “544868-5G”, average particle size of primary particles 50 nm) was used instead of the copper nitride powder. The material was made. About the obtained comparative bonding material, the bonding strength measurement test and the decomposition temperature measurement test were performed in the same manner as in Example 1. The results are shown in Table 1.

<Test results>
As is clear from the comparison between the results of Example 1 shown in Table 1 and the results of Comparative Examples 1 to 4, the decomposition temperature of the copper nitride powder of Example 1 is as low as 440 ° C., and the copper plate and the copper circle at 450 ° C. It was possible to join the plates. Further, the bonding strength between the copper plate and the copper disc was 2 MPa or more, and it was confirmed that a strong sintered structure was formed. On the other hand, when the copper powder or the copper oxide powder of Comparative Examples 1 to 4 was used, the copper powder and the copper oxide powder did not melt at 450 ° C. and no sintering was observed. Note that the bonding strength could not be measured in any of Comparative Examples 1 to 4.

  As is apparent from the results shown in Table 1, the sinterable bonding material of the present invention is a bonding material that does not need to be treated in a reducing atmosphere such as hydrogen and can obtain a high bonding strength at a relatively low temperature. It was confirmed that there was. Furthermore, the bonding method using such a sinterable bonding material enables bonding by a safe method without using dangerous gas atmosphere conditions such as hydrogen, and can be sintered at a relatively low temperature. As a result, it was confirmed that it was possible to obtain a joint having excellent joint strength.

As described above, according to the present invention, a sinterable bonding material that does not require treatment in a reducing atmosphere such as hydrogen and can obtain a high bonding strength at a relatively low temperature, and a bonding method using the same Can be provided.
Therefore, the sinterable bonding material of the present invention can be suitably used as a bonding material used when bonding a metal member and an object to be bonded. In particular, a sinterable bonding material used for bonding a metal member such as a circuit layer such as an electrode or wiring of an electronic component such as a semiconductor device and an electronic member such as a semiconductor element, and the like It is useful as a joining method.

Claims (7)

  A sinterable bonding material comprising copper nitride particles.   2. The sinterable bonding material according to claim 1, wherein an average particle diameter of primary particles of the copper nitride particles is 1 nm to 5 μm.   The sinterable bonding material according to claim 1 or 2, wherein a decomposition temperature of the copper nitride particles is 150 to 500 ° C.   Content of the said copper nitride particle exists in the range of 60-95 mass% with respect to 100 mass% of the said sinterable joining materials, It is any one of Claims 1-3 characterized by the above-mentioned. Sinterable bonding material.   The sinterable bonding material further contains a dispersion medium, and the dispersion medium is at least one selected from the group consisting of esters, alcohols, glycol ethers, carboxylic acids, and aromatic hydrocarbons. The sinterable bonding material according to any one of claims 1 to 4, wherein: A method of joining a metal member and a joined body via a joined surface,
The sinterable bonding material according to any one of claims 1 to 5 between a bonded surface of the metal member and a bonded surface of the bonded body and / or an outer edge portion of both bonded surfaces. In a joining method, heat treatment is performed in a state where the metal member is disposed, the sinterable joining material is sintered, and the metal member and the object to be joined are joined.   The joining method according to claim 6, wherein a treatment temperature in the heat treatment is 150 to 500 ° C.