Znal eutectoid alloy bonding material, bonded body, and method for manufacturing bonded body

Abstract

An objective of the present invention is to provide: a ZnAl eutectoid alloy bonding material that is capable of solving one or both of the problems of achieving improved physical characteristics as a bonding material and improving bond quality pertaining to a bonded body; a bonded body formed by using the ZnAl eutectoid alloy bonding material; and a method for manufacturing the bonded body. The ZnAl eutectoid alloy bonding material of the present invention contains a ZnAl eutectoid alloy having Zn and Al as basic compositions, the ZnAl eutectoid alloy bonding material being characterized by containing 25-28 mass% of Al, the balance being Zn and inevitable impurities.

Description

ZnAl eutectoid alloy bonding material, bonded body, and method for manufacturing the bonded body

[0001] The present invention relates to a ZnAl eutectoid alloy joining material, a joined body, and a method for manufacturing the joined body.

[0002] In recent years, devices using SiC or GaN for the semiconductor portion, which exhibit superior semiconductor properties, have been attracting attention as an alternative to devices using Si for the semiconductor portion. While the operating temperature of devices using Si for the semiconductor portion is approximately 150°C, devices using SiC or GaN for the semiconductor portion can operate at temperatures of approximately 200°C to 250°C or even higher. Therefore, there is a demand for bonding materials with high melting points to be used in devices that operate under such high temperature conditions.

[0003] Here, lead-containing solder is available as a joining material that can be used in high-temperature environments. However, in consideration of the adverse effects of lead on the environment and the human body, there is a desire to avoid the use of lead-containing solder as much as possible. Specifically, in Europe, the RoHS Directive prohibits the use of lead-containing solder in devices that operate in low-temperature ranges, and there is a demand for the provision of lead-free joining materials that can be used in devices that operate in high-temperature ranges.

[0004] In order to meet such demands, ZnAl eutectoid alloy materials have been attracting attention as joining materials that can replace lead-containing solders, as disclosed in the following Patent Document 1. The ZnAl eutectoid alloy joining material disclosed in Patent Document 1 is composed of a 17 to 30 wt% Al-0 to 1.5 wt% Cu-0 to 0.5 wt% Mg—Zn system, and is said to be used to join objects by utilizing the superplastic phenomenon.

[0005] The ZnAl eutectoid alloy bonding material disclosed in Patent Document 1 is intended to be used as sheet solder, which is prepared by rapidly cooling the ZnAl eutectoid alloy to refine the crystal grains, then cutting and forming the material into a plate. When the ZnAl eutectoid alloy bonding material disclosed in Patent Document 1 is bonded to a workpiece, the workpiece and the ZnAl eutectoid alloy bonding material are bonded together by applying a pressure of 5 to 50 MPa and maintaining the temperature at 200 to 275°C, at which the ZnAl eutectoid alloy exhibits superplasticity, for a predetermined time, thereby bringing the workpiece and the ZnAl eutectoid alloy bonding material into close contact with each other, and then heating the temperature to 280 to 410°C, thereby performing diffusion bonding.

[0006] JP 2009-113050 A

[0007] The present inventors have conducted extensive research into joining materials made of ZnAl eutectoid alloy materials, and as a result have found a first problem: that is, to further improve the physical properties of joining materials made of ZnAl eutectoid alloy materials.

[0008] Furthermore, the present inventors have found a second problem that they would like to further improve the joining quality when using a joining material made of a ZnAl eutectoid alloy material. Specifically, the present inventors have found a second problem that they would like to further improve the joining quality, such as improving the shear strength when using a joining material made of a ZnAl eutectoid alloy material and the amount of joining material that flows out from the edges of the joined parts during joining.

[0009] After further intensive research, the inventors have discovered that, in light of recent technological trends such as a rapid increase in the packaging density of electronic components such as semiconductor chips, the suppression of outflow, among the second problem in terms of bonding quality, is a problem that particularly requires improvement. Specifically, the inventors have intensively investigated a bonding material made of a ZnAl eutectoid alloy material, assuming its use as a die bond material for fixing a die (chip) to a substrate. As a result, it has been found that a bonding material made of a ZnAl eutectoid alloy material may melt during bonding and flow out beyond the outer edge of the chip, potentially causing defects such as short-circuiting between adjacent chips. In particular, when multiple rectangular chips measuring 5 mm square to 15 mm square or larger, such as power semiconductor chips, are arranged and bonded on a substrate, the spacing between adjacent chips becomes small, making it important to suppress the outflow of the bonding material. Therefore, the present inventors have found a problem in that when joining objects to be joined to a base material using a joining material made of a ZnAl eutectoid alloy material, it is desirable to improve joining quality by minimizing the outflow from the outer edges of the objects to be joined.

[0010] Therefore, the present invention aims to provide a ZnAl eutectoid alloy joining material that can solve either or both of the above-mentioned first problem of improving the physical properties as a joining material and the second problem of improving the joining quality, a joined body made using the ZnAl eutectoid alloy joining material, and a method for manufacturing the joined body.

[0011] (A1) The ZnAl eutectoid alloy bonding material of the present invention is a ZnAl eutectoid alloy bonding material comprising a ZnAl eutectoid alloy having a basic composition of Zn and Al, and contains Al in a range of 25 mass% to 28 mass%, with the remainder being Zn and inevitable impurities.

[0012] (A2) The ZnAl eutectoid alloy bonding material of the present invention may further contain, as part of the basic composition, either or both of Cu in a range of less than 2.0 mass % and Mg in a range of less than 2.0 mass %.

[0013] (A3) The ZnAl eutectoid alloy joining material of the present invention preferably has a solidus temperature of 450°C or less.

[0014] (A4) The ZnAl eutectoid alloy joining material of the present invention preferably has a difference between the liquidus temperature and the solidus temperature of 50°C or more and 150°C or less.

[0015] (B1) The joined body of the present invention comprises a substrate and a joining part comprising a ZnAl eutectoid alloy joining material, and the ZnAl eutectoid alloy joining material has a basic composition of Zn and Al, containing Al in a range of 25 mass% to 28 mass%, with the remainder being Zn and inevitable impurities.

[0016] (B2) In the joined body of the present invention, the ZnAl eutectoid alloy joining material preferably further contains, as the basic composition, either or both of Cu in a range of less than 2.0 mass% and Mg in a range of less than 2.0 mass%.

[0017] (B3) In the joined body of the present invention, the joining portion is formed by joining the joining object to the base material via the joining object to be joined to the base material and the ZnAl eutectoid alloy joining material arranged between the base material, and at the joining portion, the amount of the ZnAl eutectoid alloy joining material protruding from the outer edge of the joining object is preferably 3 mm or less, and even more preferably 2 mm or less.

[0018] (B4) In the joined body of the present invention, the ZnAl eutectoid alloy joining material preferably has a solidus temperature of 450° C. or less.

[0019] (B5) In the joined body of the present invention, the difference between the liquidus temperature and the solidus temperature of the ZnAl eutectoid alloy joining material is preferably 50°C or more and 150°C or less.

[0020] (C1) The manufacturing method of the joined body of the present invention is a manufacturing method of the joined body that has a joint that comprises a base material and a ZnAl eutectoid alloy joining material, and the ZnAl eutectoid alloy joining material is a material that has Zn and Al as a basic composition, and contains Al in the range of 25 mass% or more and 28 mass% or less, and contains Zn and inevitable impurities as the remainder, and the manufacturing method of the joined body includes the following steps: an adhesion improving step of contacting the base material and the ZnAl eutectoid alloy joining material with each other under non-heated condition and applying pressure to improve the adhesion between the base material and the ZnAl eutectoid alloy joining material; and a joining step of joining the base material and the ZnAl eutectoid alloy joining material that are brought into contact with each other in the adhesion improving step by heating the base material and the ZnAl eutectoid alloy joining material under a temperature condition that allows them to be joined.

[0021] (C2) In the method for producing a bonded body of the present invention, at least the bonding step is preferably carried out in an atmosphere having an oxygen concentration of 30 ppm or less.

[0022] (C3) In the method for producing a bonded body of the present invention, in the adhesion improving step, the pressure applied to the base material and the bonding material may be increased at a rate lower than 1 mm / min.

[0023] (C4) In the method for manufacturing a bonded body of the present invention, the adhesion improving step may be a preheating treatment in which a pressure is applied to the base material and the bonding material under a temperature condition that is lower than the bonding temperature at which bonding is possible in the bonding step.

[0024] (C5) In the method for manufacturing a bonded body of the present invention, when the pressure applied to the base material and the bonding material in the bonding step is a bonding pressure, the pressure applied to the base material and the bonding material in the preheat treatment may be a preheat pressure that is lower than the bonding pressure.

[0025] (C6) The method for manufacturing a bonded body of the present invention may further include a temperature-raising step of raising the temperature to a temperature condition that enables bonding in the bonding step after the adhesion improving step, and the temperature of the atmosphere to which the base material and the bonding material are exposed may be continuously raised in the temperature-raising step.

[0026] (C7) In the method for manufacturing a bonded body of the present invention, preferably, in a step subsequent to the adhesion improving step, the pressure applied to the base material and the bonding material during the heating of the base material and the bonding material is reduced.

[0027] The above-mentioned ZnAl eutectoid alloy bonding material is preferably produced by a production method having some or all of the following features (D1) to (D6).

[0028] (D1) The above-mentioned ZnAl eutectoid alloy bonding material may be manufactured by a manufacturing method including: an alloy ingot manufacturing process for manufacturing an alloy ingot containing a ZnAl eutectoid alloy; an alloy small lump manufacturing process for manufacturing an alloy ingot from the alloy ingot by machining the alloy ingot manufactured in the alloy ingot manufacturing process to have a volume determined based on the volume of the ZnAl eutectoid alloy bonding material; a heat treatment process for heating the alloy small lump in an atmosphere at a temperature equal to or higher than the solution temperature and lower than the melting point; and a cooling process for cooling the alloy small lump heated in the heat treatment process.

[0029] (D2) The manufacturing method of the above-mentioned ZnAl eutectoid alloy bonding material may be characterized in that the alloy lump is rolled into a rolled alloy body before the heat treatment step.

[0030] (D3) The above-mentioned method for producing a ZnAl eutectoid alloy bonding material may be characterized by including a surface polishing step of polishing the surface of the ZnAl eutectoid alloy cooled in the cooling step.

[0031] (D4) The manufacturing method of the above-mentioned ZnAl eutectoid alloy bonding material may be characterized by including a surface coating process of coating the surface of the ZnAl eutectoid alloy as a process subsequent to the cooling process.

[0032] (D5) The above-described method for producing a ZnAl eutectoid alloy bonding material of the present invention may be characterized in that, in the alloy ingot production step, the alloy ingot is produced in the form of a plate.

[0033] (D6) The above-mentioned method for producing a ZnAl eutectoid alloy joining material may be characterized in that the cooling step is a step of cooling the ZnAl eutectoid alloy by water cooling.

[0034] (E1) The ZnAl eutectoid alloy bonding material of the present invention is composed of a ZnAl eutectoid alloy having a basic composition of Zn and Al, and is characterized in that it contains Al in a range of 20 mass% to 30 mass% and at least one additive element selected from the group consisting of Ag, Co, Ge, Mn, Mo, Ni, Sb, and V in a range of 0.001 mass% to 2.0 mass%, and the remainder contains Zn and inevitable impurities.

[0035] (E2) The ZnAl eutectoid alloy bonding material of the present invention may be characterized in that the additive element is selected from the group consisting of Ge, Mn, Ni, and V.

[0036] (F1) The bonded body of the present invention comprises a substrate and a bonding part comprising a ZnAl eutectoid alloy bonding material, and the ZnAl eutectoid alloy bonding material is the ZnAl eutectoid alloy bonding material of the present invention described above.

[0037] (F2) The bonded body of the present invention may be characterized in that the substrate is a copper substrate or a low-phosphorus Ni-plated substrate.

[0038] (G1) The manufacturing method of the joint of the present invention is the manufacturing method of the joint that comprises the joint portion that comprises base material and ZnAl eutectoid alloy bonding material, and the ZnAl eutectoid alloy bonding material is used as the ZnAl eutectoid alloy bonding material of claim 17 or 18, and the manufacturing method of the joint is characterized by comprising the following steps: the adhesion improving process is carried out by bringing the base material and the ZnAl eutectoid alloy bonding material into contact with each other and pressurizing the ZnAl eutectoid alloy bonding material; and the joining process is carried out by heating the base material and the ZnAl eutectoid alloy bonding material that are made to be in close contact with each other in the adhesion improving process under the temperature condition that can be joined, so that the base material and the ZnAl eutectoid alloy bonding material are joined together.

[0039] (H1) The ZnAl eutectoid alloy bonding material of the present invention is composed of a ZnAl eutectoid alloy having a basic composition of Zn and Al, and contains Ge in a range of 1.0 mass% to 5.0 mass% with the remainder being Zn and inevitable impurities, and is characterized by exhibiting a shear strength of 40 MPa or more when bonded at 350°C.

[0040] (H2) The bonded body of the present invention is a bonded body using the ZnAl eutectoid alloy bonding material according to (H1), characterized in that the substrate is a copper substrate or a Ni-plated substrate.

[0041] According to the present invention, it is possible to provide a ZnAl eutectoid alloy joining material, a joined body, and a method for manufacturing the joined body, which can solve the above-mentioned problems.

[0042] 7 is a flowchart showing a method for manufacturing a ZnAl eutectoid alloy bonding material according to one embodiment of the present invention. It is an explanatory diagram showing the configuration of a manufacturing apparatus used in manufacturing a bonded body using the ZnAl eutectoid alloy bonding material according to one embodiment of the present invention. It is a flowchart showing a method for manufacturing a bonded body using the ZnAl eutectoid alloy bonding material according to one embodiment of the present invention. It is an explanatory diagram showing a schematic diagram of changes in temperature and pressure conditions when manufacturing a bonded body using the ZnAl eutectoid alloy bonding material according to the flow shown in FIG. 3, and the bonded state between the substrate and the ZnAl eutectoid alloy bonding material. It is a table showing the chemical composition, physical properties of the alloy, and bonding properties of the sample according to Example 1. It is an explanatory diagram for explaining a method for deriving the outflow amount. It is a photograph showing the cross section of a bonded body obtained by bonding the ZnAl eutectoid alloy bonding material according to Sample 6 of Example 1 between oxygen-free copper plates, as observed by a scanning electron microscope. (a) and (b) are photographs of enlarged portions of FIG. 7. It is a photograph showing the results of an outflow characteristic evaluation test performed in Example 3 when a copper substrate was used as the substrate. 1 is a photograph showing the results of a bonding interface state evaluation test when a copper substrate is used as a base material, performed in Example 3. FIG. 2 is a graph showing the results of evaluating the relationship between heating time and shear strength by measuring the shear strength between the ZnAl eutectoid alloy bonding material according to Example 3 and a copper substrate and a low-phosphorus Ni-plated substrate. FIG. 3 is a photograph showing the results of a flow-out property evaluation test when a low-phosphorus Ni-plated substrate is used, performed in Example 3. FIG. 4 is a photograph showing the results of a bonding interface state evaluation test when a low-phosphorus Ni-plated substrate is used, performed in Example 3. FIG. 5 is a photograph showing the results of a bonding interface state evaluation test when a low-phosphorus Ni-plated substrate is used, performed in Example 3.

[0043] Hereinafter, a ZnAl eutectoid alloy joining material, a joined body, and a method for manufacturing the joined body according to one embodiment of the present invention will be described.

[0044] <<ZnAl eutectoid alloy bonding material>> The ZnAl eutectoid alloy bonding material according to one embodiment of the present invention is configured to include a ZnAl eutectoid alloy having Zn and Al as a basic composition. The ZnAl eutectoid alloy bonding material according to this embodiment may be one having only Zn and Al as a basic composition, or one further including either Cu and / or Mg as a basic composition. That is, the ZnAl eutectoid alloy bonding material according to this embodiment may be one having Zn and Al as a basic composition, one having Zn, Al and Cu as a basic composition, one having Zn, Al and Mg as a basic composition, or one having Zn, Al, Cu and Mg as a basic composition.

[0045] In the ZnAl eutectoid alloy joining material according to this embodiment, it is advisable to optimize the contents (compound amounts) of Al, Zn, Cu, and Mg, which are the basic composition, according to the required physical properties and joining characteristics.

[0046] Here, assuming that a ZnAl eutectoid alloy bonding material is used as a bonding material for various applications, such as a die bond material for fixing a die (chip) to a substrate, physical properties such as (α1) solidus temperature, (α2) liquidus temperature, (α3) difference between the liquidus temperature and the solidus temperature, (α4) maximum load, (α5) strength, (α6) elongation, and (α7) hardness are assumed. The solidus temperature is the lower limit of the temperature at which the ZnAl eutectoid alloy changes from solid to liquid, and serves as an indicator for setting the bonding temperature. The liquidus temperature is the upper limit of the temperature at which the ZnAl eutectoid alloy completely changes from solid to liquid, and serves as an indicator for appropriately determining the heating temperature during bonding.

[0047] Here, the maximum load of the ZnAl eutectoid alloy bonding material refers to the maximum force that the ZnAl eutectoid alloy bonding material can withstand before breaking, and is considered to be an important index when evaluating the mechanical strength of the bonding material. Furthermore, the strength of the ZnAl eutectoid alloy bonding material indicates its resistance to external forces and is an important index for judging the durability and reliability of the bonding material. The elongation indicates the relative increase in length that the ZnAl eutectoid alloy bonding material can extend before breaking, and can be an index of durability against deformation, impact, or vibration. The hardness is an index of the resistance of the ZnAl eutectoid alloy bonding material to damage by other objects, and is an important index for judging the wear resistance and lifespan of the bonding material.

[0048] When it is assumed that a ZnAl eutectoid alloy bonding material is used as a bonding material, such as a die bond material for fixing a die (chip) to a substrate, it is preferable that some or all of the various physical properties described above satisfy the following criteria: (α1) Solidus temperature: 450°C or less (α2) Liquidus temperature: 540°C or less (α3) Difference between liquidus temperature and solidus temperature: 50°C or more and 150°C or less (α4) Maximum load: 2500 [N] or more (α5) Strength: 100 [MPa] or more (room temperature) (α6) Elongation: 1 [%] or more (α7) Hardness: 10 [Hv] or more

[0049] Furthermore, when a ZnAl eutectoid alloy bonding material is used as a bonding material for various applications, such as a die bond material for fixing a die (chip) to a substrate, the bonding characteristics include (β1) maximum load, (β2) shear strength, and (β3) outflow rate. Here, the maximum load refers to the maximum force that the bond can withstand before breaking, and is an important indicator for evaluating the durability and reliability of a bond formed using a ZnAl eutectoid alloy bonding material. Furthermore, the shear strength indicates the strength of the bond against the force applied per unit area, and is an important indicator for evaluating the reliability and durability of the bond. In this specification, "shear strength" refers to the bonding strength measured by a lap joint test. The outflow rate indicates the amount of ZnAl eutectoid alloy bonding material that flows out of the bond during the bonding process. Excessive outflow may reduce the mechanical strength of the bond and may cause adverse effects on adjacent components, such as short circuits and mechanical interference. Therefore, by keeping the flow rate below an acceptable level, joint quality and performance can be optimized, improving the overall reliability of the product.

[0050] When a ZnAl eutectoid alloy bonding material is used as a bonding material, such as a die bond material for fixing a die (chip) to a substrate, it is preferable that some or all of the above-mentioned various bonding characteristics satisfy the following criteria: (β1) Maximum load: 1400 [N] or more (β2) Shear strength: 50 [MPa] or more (room temperature) (β3) Flow amount: 2.00 [mm] or less

[0051] The ZnAl eutectoid alloy bonding material may be optimized in terms of the content (amount) of Al, Zn, Cu, and Mg in its basic composition so as to satisfy some or all of the above-mentioned physical properties (α1) to (α7) and the bonding properties (β1) to (β3). Specifically, to lower the solidus temperature and liquidus temperature, the ZnAl eutectoid alloy bonding material may contain at least one of Cu and Mg in its basic composition, preferably 2.0% by mass or less of Cu and / or 2.0% by mass or less of Mg. Furthermore, to improve the physical properties of the ZnAl eutectoid alloy bonding material, such as maximum load and strength, the ZnAl eutectoid alloy bonding material may have an Al content of more than 22% by mass, and more preferably 25% by mass or more. Furthermore, in order to improve hardness and suppress elongation, the ZnAl eutectoid alloy bonding material should preferably contain not only Al and Zn as the basic composition, but also at least one of Cu and Mg.

[0052] Furthermore, if the ZnAl eutectoid alloy bonding material is intended to suppress the outflow of the bonding material when bonding objects to a substrate, the ZnAl eutectoid alloy bonding material contains Al and Zn as its basic composition, but does not contain Cu or Mg, and contains Al in a range of 22% by mass to 28% by mass, preferably 25% by mass to 28% by mass, or if the basic composition further contains either Cu or Mg in addition to Al and Zn, and contains Al in a range of 22% by mass to 28% by mass, and Cu and Mg each in a range of less than 2.0% by mass. If the purpose is to improve the maximum load and shear strength when bonding objects to a substrate, the ZnAl eutectoid alloy bonding material preferably contains Al in a range of 22% by mass to 28% by mass.

[0053] <<Method for Producing ZnAl Eutectoid Alloy Joining Material>> Hereinafter, one embodiment of a method for producing a ZnAl eutectoid alloy joining material having the above-described characteristics will be described.

[0054] As shown in the flowchart of Fig. 1, the manufacturing method of the ZnAl eutectoid alloy bonding material of this embodiment is roughly divided into a plurality of steps including an alloy ingot manufacturing step, an alloy nodule manufacturing step, a heat treatment step, a cooling step, a surface oxide film removing step, and a surface coating step. Hereinafter, the manufacturing method of the ZnAl eutectoid alloy bonding material will be explained step by step with reference to the flowchart of Fig. 1.

[0055] <Alloy Ingot Preparation Step> In the manufacturing method of the ZnAl eutectoid alloy bonding material of this embodiment, first, in the alloy ingot preparation step of step 1-1, an alloy ingot containing a ZnAl eutectoid alloy is prepared. The alloy ingot containing the ZnAl eutectoid alloy is prepared, for example, by preparing raw materials for the ZnAl eutectoid alloy bonding material containing the basic composition of Al, Zn, Cu, and Mg in a predetermined ratio. The prepared raw materials for the ZnAl eutectoid alloy bonding material are placed in a crucible or sagger set in a melting furnace such as a high-frequency melting furnace, melted in an inert gas atmosphere such as argon gas or nitrogen gas, and then cast into a mold or the like in the atmosphere.

[0056] The alloy ingot containing the ZnAl eutectoid alloy can have a specific shape such as a plate, a rectangular parallelepiped, a cube, a sphere, etc., or can have an unspecified shape, etc. In the manufacturing method of the ZnAl eutectoid alloy bonding material of this embodiment, from the viewpoint of ease of processing in the steps subsequent to the alloy ingot manufacturing step, ensuring stable quality, etc., it is preferable that the alloy ingot manufacturing step manufactures an alloy ingot containing the ZnAl eutectoid alloy as a plate-shaped ingot having a predetermined thickness.

[0057] <Alloy Lump Production Step> Once an alloy ingot containing a ZnAl eutectoid alloy is prepared in the alloy ingot production step according to step 1-1 described above, the manufacturing process proceeds to the alloy ingot production step of step 1-2. The alloy ingot production step is a step of machining the alloy ingot produced in the alloy ingot production step to produce alloy ingots of a volume specified based on the volume of the ZnAl eutectoid alloy bonding material finally produced from the alloy ingot. When an alloy ingot containing a ZnAl eutectoid alloy is prepared as a plate-shaped ingot having a predetermined thickness in the alloy ingot production step described above, it is possible to easily and stably produce alloy ingots of a predetermined volume by determining the length and width so as to obtain a predetermined area and cutting the ingot.

[0058] <Heat Treatment Step> Once the alloy lump containing the ZnAl eutectoid alloy is prepared in the alloy lump preparation step according to step 1-2 described above, the manufacturing process proceeds to the heat treatment step of step 1-3. The heat treatment step is a step in which the alloy lump is heated in an atmosphere at a temperature equal to or higher than the solution temperature and lower than the melting point. The heat treatment step may be a step in which the alloy lump containing the ZnAl eutectoid alloy is heated under atmospheric pressure, but it is also preferable to use a step in which, in addition to heating the alloy lump containing the ZnAl eutectoid alloy, it is pressurized and rolled to produce a rolled alloy body.

[0059] <Cooling Step> After the heating and rolling of the alloy lump containing the ZnAl eutectoid alloy are performed in the heat treatment step according to step 1-3 described above, the manufacturing process proceeds to the cooling step of step 1-4. The cooling step is a step of cooling the alloy lump containing the ZnAl eutectoid alloy or the rolled alloy body heated in the heat treatment step. The cooling of the alloy lump or the rolled alloy body in the cooling step can be achieved by various methods, such as furnace cooling in the heating furnace used in the heat treatment step, air cooling after removal from the heating furnace, natural cooling in a specific gas atmosphere outside the heating furnace, or cooling using a refrigerant such as water or liquid nitrogen. Considering that water is a refrigerant characterized by both high thermal conductivity and specific heat, it is preferable to cool the rolled alloy body using water as the refrigerant.

[0060] <Surface Oxide Layer Removal Step> Once the cooling of the ZnAl eutectoid alloy is completed in the cooling step according to step 1-4 described above, the manufacturing process proceeds to step 1-5, the surface oxide layer removal step. The surface oxide layer removal step is a step of removing the oxide film covering the surface of the ZnAl eutectoid alloy cooled in the cooling step, and may be performed by a method of removing the oxide film from the surface of the ZnAl eutectoid alloy by polishing the surface. The surface oxide layer removal step may be performed as long as it can remove the oxide layer on the surface of the ZnAl eutectoid alloy. For example, a mechanical method such as mechanical polishing, or a chemical method using high-temperature hydrogen or a reducing agent may be suitably used to remove the surface oxide layer.

[0061] <Surface Coating Step> Once the surface polishing of the ZnAl eutectoid alloy is completed in the surface polishing step according to step 1-5 described above, the manufacturing process proceeds to step 1-6, the surface coating step. The surface coating step is a step for preventing the surface of the ZnAl eutectoid alloy from being oxidized by coating the surface of the ZnAl eutectoid alloy, from which the surface oxide film has been removed in the surface oxide film removal step, with another substance. The coating substance used to coat the surface of the ZnAl eutectoid alloy in the surface coating step should preferably be one that does not adversely affect beyond acceptable ranges the adhesion and durability to the ZnAl eutectoid alloy, or the electrical conductivity, joining characteristics, ease of use, etc., when used as a ZnAl eutectoid alloy joining material. From this perspective, the coating substance used in the surface coating step should preferably be composed of, for example, a metal such as gold, silver, copper, platinum, or nickel, or a conductive nonmetal. In addition, the surface coating step may be performed by coating the surface of the ZnAl eutectoid alloy, including the ZnAl eutectoid alloy, with a coating substance using a deposition method such as vacuum deposition, CVD, or EVD, or a method such as plating or sputtering.

[0062] The ZnAl eutectoid alloy bonding material manufactured by the above-mentioned manufacturing method of the ZnAl eutectoid alloy bonding material can form a bonded body including a predetermined substrate and a bonding part including the ZnAl eutectoid alloy bonding material. The formation (bonding) of the bonded body using the above-mentioned ZnAl eutectoid alloy bonding material can be realized by the manufacturing method of the bonded body described below. The manufacturing method of the bonded body using the ZnAl eutectoid alloy bonding material will be described in more detail below.

[0063] <<Method for manufacturing a bonded body using a ZnAl eutectoid alloy bonding material>> A method for manufacturing a bonded body using a ZnAl eutectoid alloy bonding material according to this embodiment will be described below. The bonded body using the ZnAl eutectoid alloy bonding material can be manufactured, for example, by using a manufacturing apparatus 10 shown in Figure 2. Specifically, the manufacturing apparatus 10 has a main body 20 formed to be hollow.

[0064] An inlet 24 and an outlet 26 are connected to the main body 20 by piping. A gas supply source 30 for supplying an inert gas such as nitrogen or argon is connected to the inlet 24. An oxygen concentration meter 40 is connected to the outlet 26. As a result, the manufacturing apparatus 10 can replace the inside of the main body 20 with the inert gas by supplying the inert gas from the inlet 24 while discharging the gas present inside the main body 20 from the outlet 26.

[0065] A pressure device 50 is provided inside the main body 20. The pressure device 50 includes a first clamping unit 52 and a second clamping unit 54 that are arranged opposite each other and are movable relative to each other. In this embodiment, the first clamping unit 52 is connected to a power source (not shown) and is movable toward and away from the second clamping unit 54. In the pressure device 50, a region between the first clamping unit 52 and the second clamping unit 54 serves as a placement unit 56 for placing the substrate and the ZnAl eutectoid alloy joining material. The pressure device 50 can apply pressure to the substrate and the ZnAl eutectoid alloy joining material placed in the placement unit 56 by bringing the first clamping unit 52 and the second clamping unit 54 close to each other. Furthermore, the pressure device 50 can control the magnitude of the pressure applied to the substrate and the ZnAl eutectoid alloy joining material placed in the placement unit 56 by controlling the operation of the power source using a pressure control device (not shown).

[0066] The manufacturing apparatus 10 also includes a heating device 60 for heating the substrate and the ZnAl eutectoid alloy joining material installed in the installation section 56 of the pressurizing device 50. In the illustrated example, heating elements 62, 64 built into the first clamping section 52 and the second clamping section 54 function as the heating device 60. The heating device 60 includes a temperature measuring device 66, such as a thermocouple, and a heating control device 68. The temperature measuring device 66 can directly or indirectly measure the temperatures of the substrate and the ZnAl eutectoid alloy joining material installed in the installation section 56. The heating device 60 controls the heat generation (current control) of the heating elements 62, 64 based on the temperatures of the substrate and the ZnAl eutectoid alloy joining material measured by the temperature measuring device 66, thereby heating the substrate and the ZnAl eutectoid alloy joining material under predetermined conditions.

[0067] In the method for manufacturing a joined body using the ZnAl eutectoid alloy joining material of this embodiment, a joined body can be manufactured by joining the substrates to be joined and the ZnAl eutectoid alloy joining material by heating and pressurizing them, as in the manufacturing apparatus 10 described above. As shown in the flowchart of Figure 3, the manufacturing method of this embodiment can be realized through multiple steps, broadly including a step of placing the objects to be joined, a step of reducing the oxygen concentration, a step of improving adhesion, a step of increasing the temperature, and a joining step. Furthermore, the manufacturing method of this embodiment can be realized by changing the temperature conditions and the pressure as shown in Figure 4. Below, the manufacturing method of a joined body using the ZnAl eutectoid alloy joining material will be explained step by step in accordance with the flowchart of Figure 3.

[0068] In the manufacturing method of the joined body using the ZnAl eutectoid alloy joining material of this embodiment, first, in the joining object placing step 2-1, the joining objects are placed. When using the manufacturing apparatus 10 shown in Fig. 2, the joining objects, which include the base material and the ZnAl eutectoid alloy joining material, are placed on the placing section 56 of the pressure device 50 so that they are overlapped in the approaching and separating directions of the first clamping section 52 and the second clamping section 54, thereby placing the joining objects on the manufacturing apparatus 10.

[0069] <Oxygen Concentration Reduction Process> Once the placement of the objects to be joined is completed in the above-described object placement process, the manufacturing process proceeds to the oxygen concentration reduction process of step 2-2. In the oxygen concentration reduction process, a process of reducing the oxygen concentration in the region where the objects to be joined are placed is performed. When using the manufacturing apparatus 10 shown in FIG. 2 , an inert gas such as nitrogen or argon is supplied from the gas supply source 30 via the introduction section 24 while checking the oxygen concentration remaining inside the main body 20 where the objects to be joined are placed using the oxygen concentration meter 40. This replaces the air present inside the main body 20 with the inert gas, and reduces the oxygen concentration in the region where the objects to be joined are placed to a predetermined value or less (e.g., 30 ppm or less).

[0070] <Adhesion Improvement Step> When the oxygen concentration in the region where the joining objects are placed is sufficiently reduced in the oxygen concentration reduction step, the manufacturing process proceeds to the adhesion improvement step of step 2-3. In the adhesion improvement step, the substrate and the ZnAl eutectoid alloy joining material are brought into contact with each other and pressurized, thereby improving the adhesion between the substrate and the ZnAl eutectoid alloy joining material. When using the manufacturing apparatus 10 shown in FIG. 2, the substrate and the ZnAl eutectoid alloy joining material are arranged in the installation section 56 of the pressure device 50 so as to overlap in the approaching and separating directions of the first clamping section 52 and the second clamping section 54, and then clamped by the first clamping section 52 and the second clamping section 54 constituting the pressure device 50.

[0071] Here, in the adhesion improving process, the temperature condition and pressure condition of the substrate and the ZnAl eutectoid alloy bonding material can be optimized to improve the adhesion between the substrate and the ZnAl eutectoid alloy bonding material.Specifically, the adhesion improving process can be, for example, in the non-heated state (room temperature), the substrate and the ZnAl eutectoid alloy bonding material are in contact with each other and pressure is applied, but as shown in Fig. 4, the temperature range (hereinafter also referred to as "adhesion improving temperature range") that is lower than the bonding temperature (or the temperature rise start temperature in the heating process described later) and higher than the non-heated state (room temperature) is preferably the temperature range (hereinafter also referred to as "adhesion improving temperature") that is higher than the non-heated state (room temperature), or a predetermined temperature (hereinafter also referred to as "adhesion improving temperature") in the adhesion improving temperature range. Specifically, the adhesion improvement process is preferably carried out by heating the ZnAl eutectoid alloy bonding material in a temperature range of 100°C to 150°C, which is lower than the joining temperature (or the temperature at which heating starts in the heating process described later) and higher than the temperature in the unheated state (room temperature), and applying a light load (for example, 1 MPa or less) to the ZnAl eutectoid alloy bonding material so that the ZnAl eutectoid alloy bonding material is softened and adhered to the substrate.

[0072] Furthermore, the pressure applied to the substrate and the ZnAl eutectoid alloy joining material is preferably increased at a rate equal to or lower than a predetermined upper limit of the pressure application rate. The upper limit of the pressure application rate can be set appropriately, for example, as an experimentally determined value or a value calculated based on a predetermined formula. Based on the considerations in the examples described later, the upper limit of the pressure application rate is preferably set to 1 mm / min or less. In this embodiment, the adhesion improvement process improves the adhesion between the substrate and the ZnAl eutectoid alloy joining material by increasing the pressure applied to the substrate and the ZnAl eutectoid alloy joining material at a rate lower than 1 mm / min. This eliminates gaps between the substrate and the ZnAl eutectoid alloy joining material as much as possible and minimizes the amount of oxygen present between them. In addition, as described above, in the adhesion improvement process, when the ZnAl eutectoid alloy bonding material is heated and softened while being pressurized in the adhesion improvement temperature range or at the adhesion improvement temperature, as shown in the example of Figure 4, it is advisable to stop the increase of the pressure in the adhesion improvement temperature range or at the adhesion improvement temperature for a predetermined time, or to make the increase speed of the pressure slower than the increase speed under the temperature conditions outside the adhesion improvement temperature range.

[0073] In the adhesion improvement process, the pressure applied to the substrate and the ZnAl eutectoid alloy bonding material is increased until it reaches a predetermined set pressure, thereby sufficiently adhering the substrate and the ZnAl eutectoid alloy bonding material. Here, the set pressure in the adhesion improvement process can be appropriately set as, for example, an experimentally determined value or a value calculated based on a predetermined calculation formula. For example, in consideration of the examples described later, it is preferable to set it to 0.005 [mm / min] or less. Specifically, the lower limit of the set pressure in the adhesion improvement process is preferably set to a pressure of 3 [MPa] or more. In addition, the upper limit of the set pressure in the adhesion improvement process is preferably set in consideration of, for example, the strength of the substrates to be bonded using the ZnAl eutectoid alloy bonding material and the bonded objects such as semiconductor components.

[0074] <<Heating Step>> Once the adhesion between the substrate and the ZnAl eutectoid alloy joining material is improved in the adhesion improvement step of step 2-3 described above, the manufacturing process proceeds to the heating step of step 2-4. The heating step is a step of raising the ambient temperature to which the substrate and the ZnAl eutectoid alloy joining material are exposed from an unheated state (room temperature) to a temperature condition that allows bonding in the joining step described below. For example, if the ZnAl eutectoid alloy joining material contains a ZnAl eutectoid alloy as its main component, it can be bonded by diffusion bonding or the like at around 395°C. Therefore, in the heating step, the ambient temperature is raised to a target temperature of 395°C or higher. The target temperature in the heating step is preferably set to a temperature higher than the temperature at which bonding is possible using the ZnAl eutectoid alloy joining material. The target temperature should be set taking into account errors due to the characteristics of the manufacturing apparatus 10 and the environment in which bonding is performed.

[0075] In the temperature-raising process, the temperature of the atmosphere to which the substrate and the ZnAl eutectoid alloy joining material are exposed is continuously raised. In the temperature-raising process, the temperature may be raised quickly to the target temperature, and there is no need to slow down the temperature-raising rate in the temperature range of 200°C to 275°C where the ZnAl eutectoid alloy disclosed in Patent Document 1 exhibits superplasticity.

[0076] <Bonding Process> In the temperature-raising process of step 2-4 described above, when the ambient temperature to which the substrate and the ZnAl eutectoid alloy joining material are exposed is raised to a temperature at which the substrate and the ZnAl eutectoid alloy joining material can be joined, the manufacturing process proceeds to the joining process of step 2-5. The joining process is a process in which the substrate and the joining material that have been bonded in the adhesion improvement process are held at the joining temperature for a predetermined holding time under temperature conditions that allow them to be joined by the ZnAl eutectoid alloy joining material. In the joining process, the substrate and the joining material are held at the joining temperature while maintaining the pressure applied to the substrate and the joining material in the adhesion improvement process, and then joined. The holding time in the joining process can be appropriately set, for example, as an experimentally determined value or a value calculated by calculation based on a predetermined formula or the like.

[0077] The ZnAl eutectoid alloy joining material, the manufacturing method of the ZnAl eutectoid alloy joining material, the joined body, and the manufacturing method of the joined body according to the present invention, which are exemplified in the present embodiment, have the following features, which can provide the following unique effects.

[0078] (a1) The ZnAl eutectoid alloy bonding material of this embodiment is a ZnAl eutectoid alloy bonding material composed of a ZnAl eutectoid alloy having a basic composition of Zn and Al, and is characterized in that it contains Al in a range of 25 mass% to 28 mass%, with the remainder being Zn and inevitable impurities.

[0079] The ZnAl eutectoid alloy joining material of this embodiment, by having the above-mentioned configuration (a1), can realize either or both of improved physical properties as a joining material and improved joining quality.

[0080] (a2) The ZnAl eutectoid alloy bonding material of this embodiment is characterized in that the basic composition further contains either or both of Cu in a range of less than 2.0 mass% and Mg in a range of less than 2.0 mass%.

[0081] By adopting the above-mentioned (a2) configuration, the ZnAl eutectoid alloy joining material of this embodiment can realize either or both of improved physical properties as a joining material and improved joining quality.

[0082] (a3) The ZnAl eutectoid alloy joining material of this embodiment is characterized in that the solidus temperature is 450° C. or less.

[0083] By configuring the ZnAl eutectoid alloy joining material of this embodiment as described above in (a3), it can be made joinable at a joining temperature set based on the solidus temperature, which is 450°C or less.

[0084] (a4) The ZnAl eutectoid alloy joining material of this embodiment is characterized in that the difference between the liquidus temperature and the solidus temperature is 50°C or more and 150°C or less.

[0085] The ZnAl eutectoid alloy joining material of this embodiment is in a paste or semi-solid state in the temperature range between the liquidus temperature and the solidus temperature, and is in a state where the joining material can maintain a moderate viscosity while being fluid. In this state, the ZnAl eutectoid alloy joining material spreads almost evenly over the joining surfaces, achieving high-quality joining. Since the difference between the liquidus temperature and the solidus temperature of the ZnAl eutectoid alloy joining material of this embodiment is 50°C or more and 150°C or less as described in (a4) above, even if a slight temperature change occurs during joining, the ZnAl eutectoid alloy joining material spreads almost evenly over the joining surfaces, achieving high-quality joining.

[0086] (b1) The joined body of this embodiment comprises a substrate and a joining part comprising a ZnAl eutectoid alloy joining material, and the ZnAl eutectoid alloy joining material has a basic composition of Zn and Al, contains Al in the range of 25 mass% to 28 mass%, and contains Zn and inevitable impurities as the remainder.

[0087] The bonded body of this embodiment, by being configured as described above in (b1), can achieve either or both of improved physical properties at the bonded portion and improved bonding quality.

[0088] (b2) The joined body of this embodiment is characterized in that the ZnAl eutectoid alloy joining material further contains, as the basic composition, either or both of Cu in a range of less than 2.0 mass% and Mg in a range of less than 2.0 mass%.

[0089] The bonded body of this embodiment, by being configured as described above in (b2), can achieve either or both of improved physical properties at the bonded portion and improved bonding quality.

[0090] (b3) In the joined body of this embodiment, the joining portion is formed by joining the joining object to the base material via the joining object to be joined to the base material and the ZnAl eutectoid alloy joining material arranged between the base material, and at the joining portion, the amount of the ZnAl eutectoid alloy joining material protruding from the outer edge of the joining object is preferably 3 mm or less, and more preferably 2 mm or less.

[0091] The bonded structure of this embodiment, configured as in (b3) above, can suppress a decrease in mechanical strength at the bonded portion due to excessive outflow, and adverse effects on adjacent components such as short circuits and mechanical interference, etc. As a result, the bonded structure of this embodiment can optimize the quality and performance of the bonded portion and improve the overall reliability of the product.

[0092] (b4) The joined body of this embodiment is characterized in that the solidus temperature of the ZnAl eutectoid alloy joining material is 450° C. or less.

[0093] By adopting the configuration as described above in (b4), the bonded body of this embodiment can be bonded at a bonding temperature set based on the solidus temperature, which is 450° C. or less.

[0094] (b5) The joined body of this embodiment is characterized in that the difference between the liquidus temperature and the solidus temperature of the ZnAl eutectoid alloy joining material is 50°C or more and 150°C or less.

[0095] By configuring the bonded body of this embodiment as described above in (b5), even if some temperature change occurs during bonding, the material spreads approximately evenly across the bonding surfaces, and a high-quality bond can be achieved at the bonding portion.

[0096] (c1) The manufacturing method of the joined body of this embodiment is a manufacturing method of the joined body that has a joint that is composed of a base material and a ZnAl eutectoid alloy joining material, and the ZnAl eutectoid alloy joining material is a material that has Zn and Al as a basic composition, and contains Al in the range of 25 mass% to 28 mass%, and the remainder contains Zn and inevitable impurities, and the manufacturing method of the joined body of this embodiment is characterized by comprising: an adhesion improving process of contacting the base material and the ZnAl eutectoid alloy joining material and applying pressure to improve the adhesion between the base material and the ZnAl eutectoid alloy joining material; and a joining process of heating the base material and the ZnAl eutectoid alloy joining material that are brought into contact in the adhesion improving process under a temperature condition that allows them to be joined, thereby joining the base material and the joining material.

[0097] The method for manufacturing a joined body of this embodiment is performed using the above-mentioned ZnAl eutectoid alloy joining material, and therefore, the method for manufacturing a joined body of this embodiment can produce a joined body that achieves either or both of improved physical properties and improved joining quality at the joint.

[0098] (c2) The method for producing a bonded body of this embodiment is characterized in that at least the bonding step is carried out in an atmosphere with an oxygen concentration of 30 ppm or less.

[0099] By using the manufacturing method of the joined body of this embodiment as described above (c2), it is possible to suppress the oxidation of the ZnAl eutectoid alloy joining material and to suppress the decrease in shear strength due to the oxidation of the ZnAl eutectoid alloy joining material.

[0100] (c3) The method for manufacturing a bonded body of the present embodiment is characterized in that, in the adhesion improving step, the pressure applied to the base material and the bonding material is increased at a rate lower than 1 mm / min.

[0101] The manufacturing method of the joined body of this embodiment can reduce the yield stress of the ZnAl eutectoid alloy joining material by using the above (c3), thereby further improving the shear strength while suppressing the pressure required for joining.

[0102] (c4) The manufacturing method of the bonded body of this embodiment is characterized in that the adhesion improving step is a preheating treatment in which a pressure is applied to the base material and the bonding material under a temperature condition that is lower than the bonding temperature at which bonding is possible in the bonding step and higher than room temperature.

[0103] In the manufacturing method of the joined body of the present embodiment, by adopting the above-mentioned (c4), in the adhesion improving step, the ZnAl eutectoid alloy joining material can be adhered to the substrate in a softened state by applying heat and pressure under a temperature condition that is lower than the joining temperature and higher than room temperature, thereby further improving the adhesion between the substrate and the ZnAl eutectoid alloy joining material, which can contribute to further improving the joining quality.

[0104] (c5) The method for manufacturing a bonded body of this embodiment is characterized in that, when the pressure applied to the base material and the bonding material in the bonding step is set to a bonding pressure, the pressure applied to the base material and the bonding material in the preheat treatment is set to a preheat pressure that is lower than the bonding pressure.

[0105] The manufacturing method of the bonded body of the present embodiment, by adopting the above-mentioned (c5), can apply pressure under pressure conditions that are not excessively high while heating in the adhesion improving step. As a result, the manufacturing method of the bonded body of the present embodiment can make the bonding material and the base material sufficiently blend with each other in the adhesion improving step, which can contribute to improving the bonding quality.

[0106] (c6) The method for manufacturing a bonded body of the present embodiment is characterized in that, after the adhesion improving step, a temperature raising step is performed in the bonding step to raise the temperature to a temperature condition that enables bonding, and in the temperature raising step, the temperature of the atmosphere to which the base material and the bonding material are exposed is continuously raised.

[0107] By using the method for manufacturing the joined body of this embodiment as described above in (c6), the time required to reach the joining step can be shortened compared to, for example, the conventional technology described above, in which a holding period is provided in which the ZnAl eutectoid alloy is held for a predetermined time in a temperature range where the ZnAl eutectoid alloy exhibits superplasticity.

[0108] (c7) The manufacturing method of the bonded body of the present embodiment is characterized in that, in a step subsequent to the adhesion improvement step, the pressure applied to the substrate and the bonding material during the period in which the substrate and the bonding material are heated is reduced.

[0109] By using the method for manufacturing a bonded body of the present embodiment as described above in (c7), for example, it is possible to manufacture a bonded body having high product value in which deformation of the base materials is minimized while ensuring sufficient shear strength.

[0110] (d1) The manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment is characterized by including: an alloy ingot preparation step of preparing an alloy ingot containing a ZnAl eutectoid alloy; an alloy small lump preparation step of machining the alloy ingot prepared in the alloy ingot preparation step to prepare alloy small lump of a volume determined based on the volume of the ZnAl eutectoid alloy bonding material from the alloy ingot; a heat treatment step of heating the alloy small lump in an atmosphere at a temperature not lower than the solution temperature but lower than the melting point; and a cooling step of cooling the alloy small lump heated in the heat treatment step.

[0111] The manufacturing method of the ZnAl eutectoid alloy joining material exemplified in this embodiment has the feature (d1) above, so that the grain size of the ZnAl eutectoid alloy can be reduced. This can reduce the yield stress of the ZnAl eutectoid alloy joining material. Therefore, according to the manufacturing method of the ZnAl eutectoid alloy joining material exemplified in this embodiment, the pressing force required when joining using this can be reduced.

[0112] (d2) The manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment may be a method of rolling the alloy ingot to form the rolled alloy body. The rolling temperature may be either room temperature or heated.

[0113] The manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment is as described in (d2) above. By converting the alloy ingots into a very thin rolled alloy body to be used as the bonding material in the heat treatment process, the surface area to volume ratio can be increased, and the cooling rate in the subsequent cooling process can be maximized. This further refines the grain size of the ZnAl eutectoid alloy, reduces the yield stress of the ZnAl eutectoid alloy bonding material, and can be expected to exhibit superplasticity even at room temperature, making it easier to start deformation. In other words, the ZnAl eutectoid alloy bonding material can exhibit large deformation capacity at room temperature.

[0114] (d3) The manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment may include a step of removing an oxide layer on the surface of the ZnAl eutectoid alloy cooled in the cooling step, as described above. The step of removing the oxide layer on the surface may be performed by mechanically polishing the surface or by using high-temperature hydrogen, reducing chemicals, etc.

[0115] The manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment can suppress a decrease in shear strength due to oxidation of the surface of the ZnAl eutectoid alloy by using the method (d3) described above.

[0116] (d4) As described above, the manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment may preferably include a surface coating process of coating the surface of the ZnAl eutectoid alloy as a process subsequent to the cooling process.

[0117] The manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment is as described above (d4), so that the coating formed in the surface coating process can suppress the oxidation of the surface of the ZnAl eutectoid alloy, and can suppress the reduction in shear strength caused by surface oxidation.

[0118] (d5) As described above, the manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment may be characterized in that in the alloy ingot manufacturing step, the alloy ingot is manufactured into a very thin plate shape.

[0119] The manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment can form an alloy ingot with an extremely large surface area to volume ratio by using the method (d5) described above, which allows the crystal grain size of the ZnAl eutectoid alloy to be made very small even in the alloy ingot manufacturing process.

[0120] (d6) As described above, the manufacturing method of the ZnAl eutectoid alloy bonding material exemplified in this embodiment may be characterized in that the cooling step is to cool the ZnAl eutectoid alloy by water cooling.

[0121] Water is a refrigerant characterized by its extremely large latent heat of vaporization and high specific heat. In particular, the latent heat of vaporization of water is about 11 times that of liquid nitrogen, and it absorbs a large amount of heat during cooling, thereby greatly contributing to the cooling effect. In addition, water has a thermal conductivity about 5 times that of liquid nitrogen, and is involved in the transfer of heat. Therefore, by using the method (d6) described above for producing the ZnAl eutectoid alloy bonding material exemplified in this embodiment, the cooling efficiency is higher than when the ZnAl eutectoid alloy is cooled using other refrigerants in the cooling process, and the crystal grain size of the ZnAl eutectoid alloy can be made smaller.

[0122] (e1) The ZnAl eutectoid alloy bonding material of the present invention is composed of a ZnAl eutectoid alloy having a basic composition of Zn and Al, and is characterized in that it contains Al in a range of 20 mass% to 30 mass% and at least one additive element selected from the group consisting of Ag, Co, Ge, Mn, Mo, Ni, Sb, and V in a range of 0.001 mass% to 2.0 mass%, and the remainder contains Zn and inevitable impurities.

[0123] The ZnAl eutectoid alloy bonding material of the present invention, by adopting the configuration according to (e1) above, can significantly improve bonding properties such as shear strength and fluidity compared to conventional ZnAl eutectoid alloy bonding materials. In particular, the ZnAl eutectoid alloy bonding material of the present invention can maximize the properties of the ZnAl eutectoid alloy while efficiently utilizing the effects of the additive elements by setting the Al content in the range of 20% by mass to 30% by mass. Furthermore, the ZnAl eutectoid alloy bonding material of the present invention can realize improved bonding properties by utilizing the properties of each additive element by adding at least one additive element selected from the group consisting of Ag, Co, Ge, Mn, Mo, Ni, Sb, and V in the range of 0.001% by mass to 2.0% by mass. This allows the ZnAl eutectoid alloy bonding material of the present invention to provide a high-performance ZnAl eutectoid alloy bonding material that can be used with various substrates and bonding conditions.

[0124] (e2) The ZnAl eutectoid alloy bonding material of the present invention may be characterized in that the additive element is selected from the group consisting of Ge, Mn, Ni, and V.

[0125] The ZnAl eutectoid alloy bonding material of the present invention can achieve particularly excellent bonding characteristics by adopting the configuration according to (e2) above. It has been confirmed that Ge, Mn, Ni, and V, when added to a ZnAl eutectoid alloy, are particularly effective in improving shear strength, suppressing outflow, and suppressing the occurrence of Kirkendall voids. By selectively adding these elements, high shear strength and a stable bonding interface can be achieved for both copper substrates and low-phosphorus Ni-plated substrates. Furthermore, these elements are environmentally safe and readily available, making it possible to provide a bonding material that is extremely useful from a practical standpoint.

[0126] (f1) The bonded body of the present invention comprises a substrate and a bonding part comprising a ZnAl eutectoid alloy bonding material, and the ZnAl eutectoid alloy bonding material is the ZnAl eutectoid alloy bonding material of the present invention described above.

[0127] The joined body of the present invention, by adopting the configuration according to (f1) above, can realize a joined body having high shear strength and excellent reliability. By using the ZnAl eutectoid alloy joining material according to the present invention, the joined body of the present invention significantly improves the shear strength of the joint and simultaneously improves the stability of the joining interface. This enables the joined body of the present invention to maintain stable performance over a long period of time even in various usage environments. Furthermore, compared to conventional joined bodies, the joined body of the present invention has the advantage of being able to be joined at a lower temperature, making it applicable to joining of heat-sensitive members.

[0128] (f2) The bonded body of the present invention may be characterized in that the substrate is a copper substrate or a low-phosphorus Ni-plated substrate.

[0129] The bonded body of the present invention can exhibit particularly excellent bonding characteristics by adopting the configuration according to (f2) above. Copper substrates or low-phosphorus Ni-plated substrates are compatible with ZnAl eutectoid alloy bonding materials and have the property of easily forming a stable bonding interface. The ZnAl eutectoid alloy bonding material of the present invention has been confirmed to exhibit particularly high shear strength with these substrates, and the occurrence of Kirkendall voids at the bonding interface is also effectively suppressed. As a result, the present invention can provide a bonded body that is particularly useful in fields requiring high reliability, such as electronic components and automotive parts.

[0130] (g1) The manufacturing method of the joint of the present invention is the manufacturing method of the joint that comprises the joint portion that comprises base material and ZnAl eutectoid alloy bonding material, and the ZnAl eutectoid alloy bonding material is used as the ZnAl eutectoid alloy bonding material of claim 17 or 18, and the manufacturing method of the joint is characterized by comprising the following steps: a contact improvement process, in which the base material and the ZnAl eutectoid alloy bonding material are brought into contact with each other and pressurized, thereby improving the adhesion between the base material and the ZnAl eutectoid alloy bonding material; and a joining process, in which the base material and the ZnAl eutectoid alloy bonding material that are brought into contact with each other in the contact improvement process are heated under the temperature condition that can be joined, thereby joining the base material and the ZnAl eutectoid alloy bonding material.

[0131] The manufacturing method of the joined body of the present invention, by adopting the configuration according to (g1) above, enables the stable production of high-quality joined bodies. By providing an adhesion improvement process, the adhesion between the joining material and the substrate is improved, thereby improving the shear strength and stabilizing the joining interface in the subsequent joining process. Furthermore, the ZnAl eutectoid alloy joining material of the present invention allows joining at lower temperatures than conventional joining materials, minimizing the thermal effects in the joining process. This allows the manufacturing method of the joined body of the present invention to produce joined bodies using heat-sensitive components and reduce energy consumption in the manufacturing process, thereby contributing to reducing the environmental impact.

[0132] (h1) The ZnAl eutectoid alloy bonding material of the present invention is composed of a ZnAl eutectoid alloy having a basic composition of Zn and Al, and contains Ge in a range of 1.0 mass% to 5.0 mass% with the remainder being Zn and inevitable impurities, and is characterized by exhibiting a shear strength of 40 MPa or more when bonded at 350°C.

[0133] The ZnAl eutectoid alloy bonding material according to (h1) of the present invention has a basic composition of Zn and Al, and by adding Ge in a range of 1.0 mass% to 5.0 mass%, it can achieve particularly high shear strength. Specifically, as exemplified in the examples described below, the ZnAl eutectoid alloy bonding material according to (h1) of the present invention can exhibit a shear strength of 40 MPa or more even when bonded at a low temperature of 350 °C. Thus, the ZnAl eutectoid alloy bonding material according to (h1) of the present invention can obtain reliable shear strength despite being bonded at a low temperature. Furthermore, as exemplified in the examples described below, the ZnAl eutectoid alloy bonding material according to (h1) of the present invention can achieve sufficient shear strength even when bonded for a short time of 90 seconds. This greatly contributes to improving the productivity of the bonding process using the ZnAl eutectoid alloy bonding material according to (h1) of the present invention.

[0134] (h2) The bonded body of the present invention is a bonded body using the ZnAl eutectoid alloy bonding material according to (h1), characterized in that the substrate is a copper substrate or a Ni-plated substrate.

[0135] The joined body according to (h2) of the present invention uses the ZnAl eutectoid alloy joining material described in (h1), and by using a copper substrate or a Ni-plated substrate as the substrate, it is possible to obtain particularly high shear strength. Specifically, as exemplified in the examples described below, the joined body according to (h2) of the present invention can achieve a shear strength of more than 40 MPa when using a copper substrate as the substrate at 350°C. Furthermore, as exemplified in the examples described below, even when using a Ni-plated substrate as the substrate, it can stably achieve a shear strength of more than 50 MPa when using a Ni-plated substrate at 400°C. Thus, the joined body according to (h2) of the present invention can achieve high shear strength regardless of the type of substrate and can be suitably used as a practical joined body. Note that the Ni-plated substrate includes at least a low-phosphorus Ni-plated substrate and a medium-phosphorus Ni-plated substrate.

[0136] The present invention is not limited to the above-described embodiment, and appropriate modifications are conceivable within the scope of the present invention. For example, in the present embodiment, the oxygen concentration reducing step is performed prior to the adhesion improving step, but from the viewpoint of reducing the concentration of oxygen present between the substrate and the ZnAl eutectoid alloy bonding material, the oxygen concentration reducing step may be performed in parallel with the adhesion improving step under the condition that does not cause any problem in light of the purpose of the present invention.

[0137] The ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned (a1) to (a4), and it is possible for some of the components not to be satisfied within the scope of the present invention. Furthermore, the joined body and the method for manufacturing the joined body of the present invention do not need to satisfy all of the above-mentioned (b1) to (b5) and (c1) to (c7), and it is possible for some of the components not to be satisfied within the scope of the present invention. Furthermore, the method for manufacturing the ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned (d1) to (d6), and it is possible for some of the components not to be satisfied within the scope of the present invention.

[0138] Furthermore, the ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned (e1) and (e2), and it is possible for some of the configurations not to be satisfied within the scope of the present invention. Furthermore, the joined body and the manufacturing method of the joined body of the present invention do not need to satisfy all of the above-mentioned (f1) and (f2), and it is possible for some of the configurations not to be satisfied within the scope of the present invention. Furthermore, the manufacturing method of the ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned (g1), and it is possible for some of the configurations not to be satisfied within the scope of the present invention.

[0139] Furthermore, the ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned features (e1) and (e2), and it is possible for some of the features not to be satisfied within the scope of the present invention. Furthermore, the joined body and the manufacturing method of the joined body of the present invention do not need to satisfy all of the above-mentioned features (f1) and (f2), and it is possible for some of the features not to be satisfied within the scope of the present invention. Furthermore, the manufacturing method of the ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned features (g1), and it is possible for some of the features not to be satisfied within the scope of the present invention. Furthermore, the ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned features (h1), and it is possible for some of the features not to be satisfied within the scope of the present invention. Furthermore, the ZnAl eutectoid alloy joining material of the present invention does not need to satisfy all of the above-mentioned features (h1), and it is possible for some of the features not to be satisfied within the scope of the present invention. Furthermore, the bonded body of the present invention does not need to satisfy all of the configurations related to (h2) above, and may not satisfy some of the configurations as long as it does not deviate from the spirit of the present invention.

[0140] Examples of the present invention will be specifically described below. In these examples, a ZnAl eutectoid alloy joining material was prepared according to the preparation method of a ZnAl eutectoid alloy joining material according to the following [1]. A joined body was also prepared according to the preparation method of a joined body according to the following [2]. Furthermore, as described in the following [3], physical properties of the sample of the ZnAl eutectoid alloy joining material prepared by the method [1] were tested. Furthermore, as described in the following [4], the joining characteristics of the joined body prepared by the method [2] were tested.

[0141] [1] Method for Preparing ZnAl Eutectoid Alloy Bonding Materials In this example, as shown in Figure 5, ZnAl eutectoid alloy bonding materials based on Zn and Al as the basic composition, and Zn, Al, Cu, and Mg as the basic composition were prepared as samples 1 to 6. Pure Zn, pure Al, pure Cu, and pure Mg were blended in a blending ratio (mixing ratio) based on the chemical composition of each sample. The raw materials prepared in this way were placed in a graphite crucible set in a high-frequency melting furnace, heated to approximately 12.5 kW (500 ° C to 550 ° C) under an argon gas atmosphere to completely melt, and then held in the molten state for 5 minutes. The molten metal was then cast into a boat-shaped mold in air. In this way, an alloy ingot containing a ZnAl eutectoid alloy as the main component was prepared (alloy ingot preparation process).

[0142] In addition, when preparing the ZnAl eutectoid alloy bonding material, the alloy ingot mainly composed of the ZnAl eutectoid alloy prepared as described above was subjected to machining such as cutting to form alloy ingots (alloy ingot preparation process), and then subjected to a heat treatment process (heat treatment process) by holding at 375°C for 3 hours, and a cooling process (cooling process) to prepare the material.

[0143] After the cooling process, the ZnAl eutectoid alloy was polished with emery paper of P1200 to P2500 to remove the oxide film (surface polishing process), and the surface-polished ZnAl eutectoid alloy was subjected to ultrasonic cleaning for a predetermined time (3 minutes in this embodiment) and gold vapor deposition of a predetermined thickness (50 nm in this embodiment) to provide an oxidation countermeasure (surface coating process), thereby forming a ZnAl eutectoid alloy bonding material.

[0144] [2] Method for preparing a bonded body Using the ZnAl eutectoid alloy bonding material prepared as described above, a bonded body was prepared by bonding a copper substrate made of a copper plate to the ZnAl eutectoid alloy bonding material using the manufacturing apparatus 10 illustrated in the above embodiment. The copper plate constituting the copper substrate was made of a commercially available oxygen-free copper plate. The bonding surface with the ZnAl eutectoid alloy bonding material was polished with emery paper of P1200 to P2500 to remove oxide film, and then ultrasonically cleaned for a predetermined time (3 minutes in this embodiment), and then the surface was coated with gold vapor deposition of a predetermined thickness (50 nm in this embodiment).

[0145] Here, ZnAl eutectoid alloy is a metal that is very susceptible to oxidation, and has the property of easily forming a thick oxide film at high temperatures even when the oxygen concentration is 40 ppm or less. Therefore, it is important to closely bond the ZnAl eutectoid alloy and the copper substrate (base material) at room temperature and prevent the bonding surface from contacting gas. Therefore, in this example, when preparing the bonded body, as exemplified in the above embodiment, according to the flowchart shown in Figure 3, before the temperature rising step (step 2-4), the oxygen concentration of the environment in which the ZnAl eutectoid alloy bonding material and the copper substrate (base material) are placed is reduced, and the ZnAl eutectoid alloy bonding material and the copper substrate (base material) are closely bonded at room temperature.

[0146] Specifically, first, a bonding object placing process (step 2-1) is carried out, in which the ZnAl eutectoid alloy bonding material and the copper substrate (base material) are placed on the placing section 56 of the pressure device 50 in a state of being superposed on each other; then, in an oxygen concentration reducing process (step 2-2), the inside of the main body 20 is replaced with an inert gas (nitrogen gas in this embodiment) until the oxygen concentration is 1 [ppm] or less; then, in an adhesion improving process (step 2-3), the stack of the ZnAl eutectoid alloy bonding material and the copper substrate (base material) is sandwiched between the first clamping section 52 and the second clamping section 54 of the pressure device 50; and the pressure is increased at a predetermined pressure speed until it reaches a predetermined pressure (3 [MPa] in this embodiment), thereby making the ZnAl eutectoid alloy bonding material and the copper substrate (base material) highly adhere to each other.

[0147] After the adhesion improvement step (Step 2-3) was completed at room temperature as described above, a temperature-raising step (Step 2-4) was carried out in which the ZnAl eutectoid alloy joining material was sandwiched between two copper substrates (base materials) by the first clamping unit 52 and the second clamping unit 54 of the pressure device 50 in a nitrogen atmosphere with an oxygen concentration of 1 ppm or less, and the ambient temperature was raised to a temperature at which joining was performed (395°C in this embodiment). After the ambient temperature reached the joining temperature, the joining process was continued for a predetermined holding time while maintaining the temperature conditions and pressure that allowed joining in the joining process, thereby producing a joined body (hereinafter also referred to as a "joint test piece").

[0148] [3] Physical Properties of ZnAl Eutectoid Alloy Bonding Materials According to Samples 1 to 6 Test methods and test results for the physical properties of the ZnAl Eutectoid Alloy Bonding Materials according to the above-mentioned Samples 1 to 6 will be described. In this example, tests were conducted from the viewpoints of physical properties, such as (α1) solidus temperature, (α2) liquidus temperature, (α3) difference between liquidus temperature and solidus temperature (hereinafter also referred to as "solid-liquidus temperature difference"), (α4) maximum load, (α5) strength (tensile strength), (α6) elongation, and (α7) hardness. The test methods for each test are as follows:

[0149] (α1) Measurement conditions and method for solidus temperature Sample weight: Approximately 10 mg Measurement device: Differential scanning calorimeter (Rigaku Corporation, Thermo Plus DSC8230) Heating rate: 2°C / min Measurement temperature range: 100°C to 600°C Compliance standard: JIS Z 3198-1 (Method A) Measurement method: Using a differential scanning calorimeter (Rigaku Corporation, Thermo Plus DSC8230), approximately 10 mg of the measurement sample was weighed out and measured at a heating rate of 2°C / min in the range of 100°C to 600°C. The solidus temperature was determined from the obtained DSC chart using the method of JIS Z 3198-1 (Method A).

[0150] (α2) Liquidus Temperature Measurement Conditions and Method: Sample weight: Approximately 150 g; Measurement equipment: Data logger (Keyence Corporation, NR-500), K-type thermocouple, personal computer, stainless steel container; Measurement temperature: 700°C to 200°C; Compliance standard: JIS Z 3198-1 "Lead-free solder test method, Part 1: Melting temperature range measurement method"; Measurement method: A K-type thermocouple was inserted into the center of a sample (approximately 150 g) that had been completely melted in a stainless steel container and allowed to stand. The sample temperature was measured over time by natural cooling from 700°C to 200°C using a data logger (Keyence Corporation, NR-500), and a time-temperature curve, or cooling curve, was obtained. The liquidus temperature was determined from the obtained cooling curve using the melting temperature range measurement method (Method B) described in JIS Z 3198-1.

[0151] (α3) Method for deriving the difference between the liquidus temperature and the solidus temperature (solid-liquidus temperature difference) The solid-liquidus temperature difference was derived by subtracting the solidus temperature from the liquidus temperature derived by (α1) and (α2) above.

[0152] (α4) Measurement conditions and method for maximum load: Sample dimensions: total length 85 mm, grip length 15 mm, gauge length 25 mm, gauge diameter 5 mm; Measurement device: universal testing machine (Shimadzu Corporation, Autograph AG-IS 10 kN); Test speed: 5 mm / min; Measurement method: A cylindrical alloy ingot with a diameter of 15 mm and a length of 85 mm was obtained by casting, and a sample of the specified dimensions was prepared by lathe cutting. The sample was left to stand in an electric furnace at 375°C for 1 hour, removed, and immediately immersed in water at 20°C. After cooling, the sample was gripped in the universal testing machine and pulled in the longitudinal direction at room temperature at a test speed of 5 mm / min, and the maximum load [N] recorded until fracture was measured.

[0153] (α5) Strength and (α6) Method of Derivation of Elongation The maximum load obtained by (α4) was calculated by multiplying the area (19.6 mm ２ The value obtained by dividing the measured value by the gauge length when the fracture surfaces of the test specimens were butted together after the test by the gauge length before the test was determined as the strength [MPa] of the alloy composition. Furthermore, the elongation was determined by subtracting the gauge length before the test from the gauge length when the fracture surfaces of the test specimens were butted together after the test, dividing the result by the gauge length before the test, and multiplying the result by 100.

[0154] (α7) Hardness Measurement Conditions and Method: Sample dimensions: diameter 20 mm, thickness 3 mm; Measurement device: Vickers hardness tester (AKASHI MVK-F, manufactured by Akashi Seisakusho Co., Ltd.); Compliance standard: JIS Z 2244 "Vickers hardness test - Test method"; Measurement method: An alloy ingot of a predetermined composition is obtained by casting, and a cylindrical sample with a diameter of 20 mm and a thickness of 3 mm is produced by lathe cutting. The measurement surface is polished with 800-grit emery paper, and then the sample is left to stand in an electric furnace at 375°C for 1 hour. After removal, the sample is immediately immersed in water at 20°C. After cooling, the sample is left at room temperature for 24 hours before being used for measurement. Measurement and hardness calculation were performed using the method described in JIS Z 2244.

[0155] The results of tests on the physical properties (α1) to (α7) for Samples 1 to 6 described above are shown in Figure 5. The physical properties of each sample were evaluated based on the criteria exemplified in the above embodiment, and the results were as follows:

[0156] (α1) Solidus Temperature The solidus temperature was examined for Samples 1 to 6. As a result, the solidus temperature was 450°C or lower for all samples. Therefore, all of the ZnAl eutectoid alloy joining materials for Samples 1 to 6 satisfied the evaluation criteria for solidus temperature exemplified in the above embodiment. In addition, the influence of whether or not Cu and Mg are included in the basic composition on the solidus temperature was examined when the Al content is the same. As a result, it was found that Samples 2, 4, and 6, which include Cu and Mg in the basic composition, have significantly lower solidus temperatures than Samples 1, 3, and 5, which include the same Al content. Therefore, it was found that the solidus temperature of the ZnAl eutectoid alloy joining material tends to be lowered by including Cu and Mg in the basic composition.

[0157] (α2) Liquidus Temperature The liquidus temperature was examined for Samples 1 to 6. As a result, the liquidus temperature was 540°C or lower for all samples. Therefore, all of the ZnAl eutectoid alloy joining materials for Samples 1 to 6 satisfied the evaluation criteria for liquidus temperature exemplified in the above embodiment. In addition, the influence of whether or not Cu and Mg are included in the basic composition on the solidus temperature was examined when the Al content is the same. As a result, it was found that Samples 2, 4, and 6, which include Cu and Mg in the basic composition, have lower liquidus temperatures than Samples 1, 3, and 5, which include the same Al content. Therefore, it was found that the liquidus temperature of the ZnAl eutectoid alloy joining material tends to be lower when Cu and Mg are included in the basic composition.

[0158] (α3) Difference between Liquidus Temperature and Solidus Temperature (Solid-Liquidus Temperature Difference) The tendency of the solid-liquidus temperature difference was investigated for Samples 1 to 6. As a result, all samples were found to be between 50°C and 150°C, satisfying the evaluation criteria for the solid-liquidus temperature difference exemplified in the above embodiment. Furthermore, the influence of whether or not Cu and Mg are included in the basic composition on the solid-liquidus temperature difference when the Al content is the same was investigated. As a result, it was found that Samples 2, 4, and 6, which contain Cu and Mg in the basic composition, have significantly larger solid-liquidus temperature differences than Samples 1, 3, and 5, which contain the same Al content. Therefore, it was found that the inclusion of Cu and Mg in the basic composition tends to increase the solid-liquidus temperature difference of the ZnAl eutectoid alloy joining material.

[0159] (α4) Maximum Load: The maximum load trends were investigated for Samples 1 to 6. As a result, all samples had a maximum load of 2500 [N] or more, satisfying the evaluation criteria for maximum load exemplified in the above embodiment. Furthermore, when Samples 1, 3, and 5, which contain Zn and Al but do not contain Cu or Mg as their basic compositions, were examined, a tendency for the maximum load to increase with increasing Al content was observed. Furthermore, the influence of the inclusion of Cu and Mg as basic compositions on the maximum load was investigated when the Al content was the same. As a result, Samples 2 and 4, which contain Cu and Mg as basic compositions, were found to have higher maximum loads than Samples 1 and 3, which contain the same Al content. Although Sample 6, which contains Cu and Mg as basic compositions, had a lower maximum load than Sample 5, which contains the same Al content, it still satisfied the evaluation criteria for maximum load and exhibited a maximum load sufficient for a joining material.

[0160] (α5) Strength (Tensile Strength) The tensile strength trends of Samples 1 to 6 were examined. As a result, all samples had a tensile strength of 100 MPa or more, satisfying the strength evaluation criteria exemplified in the above embodiment. Furthermore, when Samples 1, 3, and 5, which contain Zn and Al but do not contain Cu or Mg as their basic compositions, were examined, a tendency for the tensile strength to increase with increasing Al content was observed. Furthermore, the influence of the inclusion of Cu and Mg as basic compositions on tensile strength was examined when the Al content was the same. As a result, Samples 2 and 4, which contain Cu and Mg as basic compositions, were found to have higher tensile strengths than Samples 1 and 3, which contain the same Al content. Although Sample 6, which contains Cu and Mg as basic compositions, had a lower tensile strength than Sample 5, which contains the same Al content, it still satisfied the tensile strength evaluation criteria and exhibited sufficient tensile strength as a joining material.

[0161] (α6) Elongation The tendency of elongation was examined for Samples 1 to 6. As a result, Samples 1 to 5 had elongation of 1% or more, which satisfied the strength evaluation criteria exemplified in the above embodiment. On the other hand, Sample 6 had elongation of 0%. Therefore, it was found that Samples 1 to 5 are optimal when elongation properties are required.

[0162] (α7) Regarding Hardness: The hardness trends of Samples 1 to 6 were examined. As a result, all samples had hardnesses of 10 [Hv] or more, satisfying the hardness evaluation criteria exemplified in the above embodiment. Furthermore, the influence of whether or not Cu and Mg are included in the basic composition on hardness was examined when the amount of Al blended was the same. As a result, it was found that Samples 2 and 4, which contain Cu and Mg as basic compositions, have greater hardness than Samples 1 and 3, which contain the same amount of Al blended.

[0163] [4] Regarding the bonding characteristics of the ZnAl eutectoid alloy bonding materials according to Samples 1 to 6, the test methods and test results for the bonding characteristics of the ZnAl eutectoid alloy bonding materials according to Samples 1 to 6 will be described. In this example, the tests were conducted in terms of (β1) maximum load, (β2) shear strength, and (β3) outflow amount as bonding characteristics. The test methods for each test are as follows. Note that test specimens (hereinafter also referred to as "joint test specimens") for testing the bonding characteristics of the ZnAl eutectoid alloy bonding materials according to Samples 1 to 6 were prepared by placing the ZnAl eutectoid alloy bonding materials (5 × 5 × 0.5 mm) according to Samples 1 to 6 between two oxygen-free copper substrates (10 × 20 × 3 mm) and bonding them using a pressure baking device ("Model HTM-3000" manufactured by Meisho Kiko Co., Ltd.).

[0164] (β1) Measurement conditions and method for maximum load Measurement device: Universal testing machine (Shimadzu Corporation, Autograph AG-IS) Tensile speed: 1 mm / min Measurement method: The joint test piece was set in the universal testing machine (Shimadzu Corporation, Autograph AG-IS), and the joint test piece was pulled in the longitudinal direction at a test speed of 1 mm / min, and the maximum load [N] recorded until the joint test piece broke was measured.

[0165] (β2) Method for deriving shear strength The shear strength was calculated by multiplying the maximum load obtained by the test using the above-mentioned method by the area (25 mm ２ ]) was used as the shear strength [MPa] of the alloy composition.

[0166] (β3) Measurement Conditions and Method of Outflow Amount: An image of the joint was taken of the joint specimen after fracture in the tensile test conducted to measure the maximum load described above. As shown in Figure 6, the fracture surface region X (dotted area in the figure) and the outflow region Y (shaded area in the figure) from which the ZnAl eutectoid alloy joining material had flowed were identified in this image. The outflow region Y was divided into four regions (outflow regions Y1 to Y4) using the diagonal lines of the fracture surface region as boundaries, and the area (maximum area S) of the largest region among the outflow regions Y1 to Y4 was divided by the length of one side of the joining material before joining (5 mm) to determine the outflow amount [mm].

[0167] The results of tests on the bonding characteristics (β1) to (β7) for Samples 1 to 6 described above are shown in Figure 5. The bonding characteristics of each sample were evaluated based on the criteria exemplified in the above embodiment, and the results were as follows.

[0168] (β1) Maximum Load The bonding characteristics of the bonded structures formed using the ZnAl eutectoid alloy bonding materials of Samples 1 to 6 were examined from the perspective of maximum load. As a result, the maximum load was 1400 [N] or more for all samples, satisfying the evaluation criteria for maximum load exemplified in the above embodiment. Furthermore, the influence of whether or not Cu and Mg are included in the basic composition on the maximum load was examined when the Al content is the same. As a result, it was found that Samples 2, 4, and 6, which contain Cu and Mg as their basic compositions, exhibited maximum loads comparable to or greater than those of Samples 1, 3, and 5, which contain the same Al content. This indicates that the inclusion of Cu and Mg in the basic composition does not adversely affect the maximum load. Furthermore, it was found that for both Sample 5, which does not contain Cu or Mg in the basic composition, and Sample 6, which contains Cu and Mg, both of which have an Al content of 28% by mass, the maximum load was slightly lower than that of Samples 1 to 4, which have an Al content of less than 28% by mass. However, for both Sample 5 and Sample 6, the maximum load was 1400 N or more, which was a sufficient value for the joining characteristics.

[0169] (β2) Shear Strength The bonding characteristics of the bonded structures formed using the ZnAl eutectoid alloy bonding materials according to Samples 1 to 6 were examined from the perspective of shear strength. As a result, all samples had shear strengths of 50 MPa or more, satisfying the evaluation criteria for shear strength exemplified in the above embodiment. Furthermore, the influence of whether or not Cu and Mg are included in the basic composition on shear strength was examined when the Al content is the same. As a result, Samples 2, 4, and 6, which contain Cu and Mg as their basic compositions, were found to exhibit shear strengths comparable to or greater than those of Samples 1, 3, and 5, which contain the same Al content. This demonstrates that the inclusion of Cu and Mg in the basic composition does not adversely affect shear strength. Furthermore, it was found that both Sample 5, which does not contain Cu or Mg in the basic composition, and Sample 6, which contains Cu and Mg, both of which have an Al content of 28% by mass, had slightly lower shear strength than Samples 1 to 4, which have an Al content of less than 28% by mass. However, both Sample 5 and Sample 6 had shear strengths of 50 MPa or more, which were sufficient values ​​for bonding characteristics.

[0170] (β3) Flow Amount The bonding characteristics of the bonded bodies formed using the ZnAl eutectoid alloy bonding materials according to Samples 1 to 6 were examined from the viewpoint of the flow amount. As a result, Samples 1 to 5 had a flow amount of 2.00 mm or less, which satisfied the evaluation criteria for the flow amount exemplified in the above embodiment. On the other hand, Sample 6 had a flow amount of 2.42 mm. Therefore, it was found that Samples 1 to 5 were optimal from the viewpoint of minimizing the flow amount.

[0171] Next, a second example will be described. In this example, the ZnAl eutectoid alloy bonding material (Zn:Al:Cu:Mg=68.0:28.0:2.0:2.0 in mass ratio) according to Sample 6 of the first example described above was placed between two oxygen-free copper plates (copper substrate: 10 × 20 × 3 mm), and the bonded body was bonded using a pressure firing device ("Model HTM-3000" manufactured by Meisho Kiko Co., Ltd.). The cross section of the bonded body was observed using a scanning electron microscope (SEM). The scanning electron microscope used for the observation and the measurement conditions were as follows. Measurement device: JSM-IT700HR (manufactured by JEOL Ltd.) Signal: BED-S Incident voltage: 15.0 kV WD: 10.1 mm Magnification: 300x Observation range: 426.7 x 320.0 μm Exposure current number Std.: 75.0 Scan rotation: 0.0 degrees Vacuum mode: Low Vacuum Degree of vacuum: 30 Pa

[0172] As a result of the SEM observation under the above-mentioned measurement conditions, the SEM observation images shown in Figures 7 and 8 were obtained. The SEM observation image in Figure 7 is a photograph showing the boundary between the bonding portion where the copper substrate is bonded with the ZnAl eutectoid alloy bonding material and the outflow portion, and Figures 8(a) and (b) are photographs showing enlarged main portions of Figure 7.

[0173] 7 and 8, it was confirmed that the copper substrates were bonded by using the ZnAl eutectoid alloy bonding material of Sample 6. Furthermore, the SEM images confirmed that the outflowing portion was not bonded and that the structure state was different between the bonding portion and the outflowing portion.

[0174] In Example 3 of the present invention, the characteristics of a ZnAl eutectoid alloy bonding material with a trace element added were evaluated. Specifically, a three-element alloy (Zn-21.78Al-1X eutectoid alloy bonding material) was prepared by adding 1 part by mass of an additive element (hereinafter also referred to as "X component") to a Zn-22Al eutectoid alloy (99 parts by mass). Here, 12 elements, Ag, Bi, Co, Cu, Ga, Ge, Mn, Mo, Ni, Sb, Si, and V, were used as the X component. When selecting these elements, environmental safety (low toxicity), availability (rarity and whether or not precious metals were used), and workability (ease of melting) were taken into consideration.

[0175] The bonding material was fabricated with dimensions of 5 × 5 × 0.5 mm. A copper substrate or a low-phosphorus Ni-plated substrate was used as the base material. The bonding conditions were set to three temperatures: 330 °C, 350 °C, and 400 °C, a holding time of 90 seconds, and a pressure of 4 MPa.

[0176] The bond was evaluated by observing the fracture surface and by shear testing the bonded interface, allowing for a detailed investigation of the influence of each X component on the shear strength and the properties of the bonded material.

[0177] In this example, in the case where copper substrate is used as a base material, a shear strength test was carried out to evaluate the shear strength of the ZnAl eutectoid alloy bonding material to which X component is added. The test equipment and test conditions used in the shear strength test are as follows.

[0178] The joint test piece for evaluating the shear strength of the ZnAl eutectoid alloy joining material to which the X component was added was prepared by disposing the ZnAl eutectoid alloy joining material to which the X component was added (5 × 5 × 0.5 mm) between two oxygen-free copper plates (copper substrate: 10 × 20 × 3 mm) and joining them using a pressure baking device ("Model HTM-3000" manufactured by Meisho Kiko Co., Ltd.).

[0179] (γ1) Measurement conditions and method for maximum load Measurement device: Universal testing machine (Shimadzu Corporation, Autograph AG-IS) Tensile speed: 1 mm / min Measurement method: The joint test piece was set in the universal testing machine (Shimadzu Corporation, Autograph AG-IS) and pulled in the longitudinal direction of the joint test piece at a test speed of 1 mm / min, and the maximum load [N] recorded until the joint test piece broke was measured.

[0180] (γ2) Method of deriving shear strength The shear strength was calculated by multiplying the maximum load obtained by the test using the above-mentioned method by the area (25 mm ２ ]) was used as the shear strength [MPa] of the alloy composition.

[0181] (Shear strength test when copper substrate is used as base material) Table 1 shows the results of the shear strength test described above. As shown in Table 1, when the bonding temperature was 400°C, it was found that the alloys containing Ge, Mn, Mo, Ni, Si, and V generally tended to exhibit higher strength than the shear strength of the ZnAl eutectoid alloy bonding material. In particular, it was found that the alloys containing Ni and V tended to exhibit strengths 10% or more higher than the shear strength of the ZnAl eutectoid alloy bonding material.

[0182]

[0183] The results of the bonding test at a bonding temperature of 350°C showed that alloys containing Ge, Mo, and V tended to exhibit higher shear strength than ZnAl eutectoid alloy bonding materials. This confirmed that the addition of Ge, Mo, and V elements is effective in low-temperature bonding processes. In particular, it was found that alloys containing Ge, Ni, and V can exhibit shear strengths 10% or more higher than those of ZnAl eutectoid alloy bonding materials. Therefore, it was found that the addition of Ge, Ni, and V elements is effective in maintaining high strength even at low bonding temperatures and in lowering the process temperature.

[0184] When the bonding test results were taken into account at a bonding temperature of 330° C., it was found that alloys containing Ge, Ni, and V could exhibit a shear strength exceeding 30.0 MPa. In particular, it was found that the addition of elements related to Ge, Ni, and V is effective in maintaining high strength even at low bonding temperatures and in lowering the process temperature.

[0185] From the above results, it was found that an alloy in which Ge, Mn, Mo, Ni, Si, or V was added as the X component in a Zn-21.78Al-1X eutectoid alloy bonding material contributes to improving shear strength, and the addition of elements related to Ge, Ni, and V is effective in maintaining high strength even under low bonding temperature conditions and in lowering the process temperature. Therefore, it was found that in situations where low-temperature bonding is required, it is effective to add elements related to Ge, Ni, and V as the X component in a ZnAl alloy.

[0186] (Test for evaluating flow characteristics when copper substrate is used as the base material) In this example, a test was conducted to evaluate the flow characteristics when copper substrate was used as the base material and the Zn-21.78Al-1X eutectoid alloy was used for bonding. The samples used in this test were prepared at a bonding temperature of 350°C, a holding time of 90 seconds, and a pressure of 4 MPa.

[0187] Photographs showing the test results of the flow-out test are shown in Fig. 9. As can be seen from Fig. 9, when using a ZnAl eutectoid alloy to which elements other than Cu (Ag, Co, Ge, Mn, Mo, Ni, Si, and V) were added, the amount of flow-out of the joining material was confirmed to be almost the same as that in the case of no addition, and to be within a preferable range. This indicates that adding elements related to Ag, Co, Ge, Mn, Mo, Ni, Si, and V as the X component does not have a significant adverse effect on the flow-out characteristics of the joining material.

[0188] On the other hand, when Cu was added as the X component, unlike when other elements were added, the amount of outflow of the joining material tended to increase. This suggests that the addition of Cu increases the fluidity of the joining material, which may result in excessive outflow at the joint. From the perspective of suppressing the outflow amount, it was found that it is preferable to add elements other than Cu as the X component, such as Ag, Co, Ge, Mn, Mo, Ni, Si, and V.

[0189] From the above results, it was confirmed that for a joining material made of a Zn-21.78Al-1X eutectoid alloy, by adding appropriate amounts of Ag, Co, Ge, Mn, Mo, Ni, Si, and V, it is possible to improve the performance of the joining material while suppressing the amount of outflow.

[0190] (Bonding Interface State Evaluation Test When Copper Substrate is Used as Base Material) In this example, a test (bonding interface state evaluation test) was conducted to evaluate the bonding interface state between a Zn-21.78Al-1X eutectoid alloy bonding material and a copper substrate. The X components used in the test were Ag, Co, Cu, Ge, Mn, Mo, Ni, Si, and V. The test was conducted using a sample bonded to a copper substrate under the conditions of a bonding temperature of 400°C, a holding time of 90 seconds, and a pressure of 4 MPa. The results are shown in Figure 10.

[0191] The structure of the diffusion layer at the bonding interface was the same regardless of the addition of any of the elements used as trace elements in this test. Specifically, as shown in Figure 10, it was confirmed that the structure of the diffusion layer at the bonding interface of the sample related to this test was a layered structure in which a Cu-Zn layer, a Cu-Al layer, and a Zn-Al bonding material layer were stacked from the Cu substrate side. Since this layered structure was the same regardless of the type of added element, it was found that a diffusion layer formed by diffusion of Zn and Al from the copper substrate could be stably formed regardless of the element added as the X component.

[0192] More specifically, in the example of the bonding interface when a V-added ZnAl eutectoid alloy bonding material was used, as shown in Figure 10, the element distributions of Cu, Zn, Al, and V could be confirmed by EDS element mapping. On the other hand, a similar test was also conducted on the bonding interface state of a Zn-22Al eutectoid alloy, and the results were compared with those of Zn-21.78Al-1V, but no significant difference was observed in the formation of the diffusion layer. This shows that the addition of V to the ZnAl alloy did not have a significant effect on the structure of the diffusion layer.

[0193] (Study on the relationship between holding time and shear strength) In this example, a ZnAl eutectoid alloy bonding material based on Zn-22Al was used to measure the shear strength with a copper substrate and with a low-phosphorus Ni-plated substrate (a copper substrate with a 5 μm-thick low-phosphorus Ni plating applied to the entire surface), and the bonding characteristics with each substrate were compared. The bonding temperature was set to 400°C and the pressure was set to 4 MPa, and the relationship between holding time and shear strength was evaluated.

[0194] As shown in Figure 11, it was confirmed that the shear strength with the copper substrate increased with increasing holding time. Based on the test results, the shear strength depended on the holding time, and the following equation was obtained: y = 13.542 ln(x) - 43.701(R ２ = 0.9685), the shear strength reached 40 MPa after heating for approximately 630 seconds.

[0195] On the other hand, it was found that a longer holding time was required to obtain the same shear strength with the low-phosphorus Ni-plated substrate compared to the copper substrate. The increase in shear strength with the low-phosphorus Ni-plated substrate was calculated as y = 9.3416ln(x) + 6.1567(R ２ = 0.919), the shear strength gradually improved as the holding time increased. For the low-phosphorus Ni-plated substrate, heating for 630 seconds or more was required for the shear strength to reach 40 MPa.

[0196] These results show that when using ZnAl eutectoid alloy bonding materials, high shear strength can be obtained with a relatively short holding time for copper substrates, while a longer holding time is required for low-phosphorus Ni-plated substrates. Therefore, it became clear that the holding time and other bonding conditions must be appropriately adjusted depending on the material of the substrate.

[0197] (Shear strength test using low-phosphorus Ni-plated substrate) In this example, a Zn-21.78Al-1X eutectoid alloy bonding material was used to evaluate the shear strength with a low-phosphorus Ni-plated substrate. The bonding temperature was 400°C, the pressure was 4 MPa, and the holding time was 630 seconds, and the shear strength was measured.

[0198] The results of the above measurements were as shown in Table 2. As shown in FIG. 2, it was confirmed that when all X components (Ag, Co, Cu, Ga, Ge, Mg, Mn, Mo, Ni, Sb, V) except for Bi were added, shear strengths equivalent to or greater than those obtained without addition were obtained. In particular, when Ag, Mg, Mn, Ni, and V were added, the shear strengths were 59.6 MPa, 54.3 MPa, 59.8 MPa, 54.2 MPa, and 56.3 MPa, respectively, which were 10% or more higher than the shear strength of the ZnAl eutectoid alloy bonding material. On the other hand, when Bi was added, the shear strength was 41.4 MPa, which was 10% or more lower than the shear strength of the ZnAl eutectoid alloy bonding material.

[0199]

[0200] These results show that the addition of Ag, Mg, Mn, Ni, and V improves shear strength, making it clear that selecting an appropriate X component is effective in optimizing shear strength when bonding to a low-phosphorus Ni-plated substrate.

[0201] (Test for evaluating flow-out characteristics when using low-phosphorus Ni-plated substrate) In this example, a ZnAl eutectoid alloy bonding material with Zn-21.78Al as the base composition and 1% by mass of trace elements was used to evaluate the amount of flow-out during bonding to a low-phosphorus Ni-plated substrate. The bonding conditions were a bonding temperature of 400°C, a pressure of 4 MPa, and a holding time of 630 seconds.

[0202] As can be seen from Figure 12, when all trace elements (Ag, Bi, Co, Cu, Ga, Ge, Mg, Mn, Mo, Ni, Sb, V) were added, the amount of outflow was equal to or, in some cases, even greater than that when no trace elements were added. It was shown that the addition of trace elements (component X) has the effect of increasing the fluidity of the joining material, and it was found that this tendency is particularly pronounced when joining low-phosphorus Ni-plated substrates. This confirms that suppressing the amount of outflow is an important factor when joining low-phosphorus Ni-plated substrates, and that the influence on fluidity must be taken into consideration when selecting trace elements.

[0203] (Test for evaluating the state of the bonding interface when using a low-phosphorus Ni-plated substrate) In this example, the state of the bonding interface between a ZnAl eutectoid alloy bonding material with Zn-21.78Al as the base composition and 1 mass% of trace elements added and a low-phosphorus Ni-plated substrate was evaluated. The bonding temperature was 400°C, the pressure was 4 MPa, and the holding time was 630 seconds. The structure and bonding characteristics of the bonding interface were investigated when Ge, Bi, Cu, Co, Mn, Ni, Sb, Ag, Mo, Ga, Mg, and V were added, respectively.

[0204] 13 and 14, regardless of which trace element was added, a layer structure of Cu (substrate), Ni (plating), Ni-Al layer, and Zn-Al (bonding material) was confirmed at the bonding interface from the substrate side. Furthermore, it was observed that bonding fractures occurred mainly at the interface between the Ni and Ni-Al layers, or the interface between the Ni-Al layer and the Zn-Al layer.

[0205] In the example of the bonding interface when using the ZnAl eutectoid alloy bonding material with Ge added shown in Figure 13, stable bonding was confirmed at the interface between the Ni-Al layer and the Zn-Al layer, and fracture occurred along the interface. A similar phenomenon was also confirmed at the bonding interface when using the ZnAl eutectoid alloy bonding material with Bi, Cu, Co, Mn, Ni, and Sb added.

[0206] On the other hand, when using the ZnAl eutectoid alloy bonding material with added Ag and Mo, as shown in Figure 14, it was confirmed that voids, which are thought to be Kirkendall voids, were generated in the Ni-Al layer. The generation of these voids may affect the shear strength, and it was suggested that process control to suppress the generation of voids is important, especially when adding Ag or Mo. A similar phenomenon was also confirmed when using the ZnAl eutectoid alloy bonding material with added Ga, Mg, and V.

[0207] The basic layer structure of the bonding interface between the ZnAl eutectoid alloy bonding material with 1% by mass of trace elements and the low-phosphorus Ni-plated substrate was not significantly different from that between the ZnAl eutectoid alloy bonding material without trace elements and the low-phosphorus Ni-plated substrate. However, it was confirmed that Kirkendall voids were generated when specific trace elements (Ag or Mo) were added. Therefore, when using the ZnAl eutectoid alloy bonding material with trace elements added, it is necessary to optimize the bonding conditions while taking this into consideration.

[0208] (Summary of Example 3) As described above, in this example, the bonding characteristics of a ZnAl eutectoid alloy bonding material with a basic composition of Zn-21.78Al and 1 mass% of trace elements added were evaluated for bonding to a copper substrate and a low-phosphorus Ni-plated substrate. The results of the above experiments are summarized in Table 3 below. Referring to Figure 3, it can be seen that the ZnAl eutectoid alloy bonding material with Ge, Mn, Ni, and V added as trace elements exhibits particularly excellent bonding characteristics.

[0209]

[0210] In a bonding test for a copper substrate, it was found that the addition of Ge, Ni, and V improved the shear strength compared to a ZnAl eutectoid alloy bonding material, and these elements were highly effective in suppressing the amount of outflow and the formation of voids. Also, in a bonding test for a copper substrate, it was found that the addition of Mn and Mo was inferior to the addition of Ge, Ni, and V in terms of shear strength, but was highly effective in suppressing the amount of outflow and the formation of voids.

[0211] In a bonding test on a low-phosphorus Ni-plated substrate, it was found that the addition of Mn and Ni was effective in both improving shear strength and suppressing voids compared to Zn-22Al eutectoid alloy bonding materials. Also, it was found that when Co, Cu, Ge, and Sb were added, the shear strength was inferior to that of when Mn and Ni were added, but good properties were shown in both shear strength and void suppression.

[0212] Taking these results together, it was found that the ternary alloy (Zn-21.78Al-1X) with Ge, Mn, Ni, and V added as trace elements can significantly improve the joining characteristics compared to the Zn-22Al eutectoid alloy joining material.

[0213] In order to study the effects of the additive elements in the ZnAl eutectoid alloy bonding material of the present invention in more detail, the inventors evaluated the influence of the type and amount of additive elements, as well as the bonding conditions, on the bonding characteristics. The ZnAl eutectoid alloy bonding material of this Example 4 was produced by the same method as in Example 1. In addition, the shear strength was also measured under the same conditions as in Example 1.

[0214] The present inventors first evaluated the influence of the bonding temperature and holding time on the bonding characteristics of a ZnAl eutectoid alloy bonding material with a basic composition (Zn: 78 mass%, Al: 22 mass%) using a medium-phosphorus Ni-plated substrate (a copper substrate plated with a medium-phosphorus Ni layer to a thickness of 5 μm on the entire surface) as the substrate. The results are shown in Table 4.

[0215] As shown in Table 4, in this Example 4, the ZnAl eutectoid alloy bonding material of the basic composition exhibited a shear strength of 36.3 MPa with a holding time of 5430 seconds when bonding at 350°C. It was also confirmed that by setting the bonding temperature to 400°C, a shear strength of 38.2 MPa was obtained with a holding time of 1830 seconds, and a shear strength of 51.6 MPa was obtained with a holding time of 3630 seconds.

[0216] Next, the inventors performed an evaluation using a copper substrate as the base material and setting the holding time to 90 seconds in order to evaluate the effect of the additive elements on bonding at a relatively low temperature of 350° C. The results are shown in Table 5.

[0217] As shown in Table 5, in Example 4, when Ge was added at 0.01 mass% and 0.1 mass%, a shear strength of approximately 20 to 30 MPa was observed, whereas by increasing the Ge content to 1.0 mass%, a high shear strength of over 90 MPa was obtained. Furthermore, it was confirmed that a high strength of over 85 MPa was maintained even when the Ge content was increased to 3.0 mass%.

[0218] On the other hand, when V was added in Example 4, the shear strength was 17 to 30 MPa in the range of 0.01 to 0.1 mass%. In addition, when Ni was added for comparison, it was confirmed that the shear strength was 19.3 MPa at an addition of 0.1 mass% and 0.2 MPa at an addition of 5.0 mass%.

[0219] The inventors also evaluated the effects of various additive elements when the bonding temperature was set to 400° C. The holding time was set to 90 seconds. The results are shown in Table 6.

[0220] As shown in Table 6, in Example 4, when the bonding temperature was 400°C, the ZnAl eutectoid alloy bonding material with 1.0 mass% Ge added exhibited shear strengths of 42.8 MPa and 49.3 MPa at Al contents of 24.75 mass% and 27.72 mass%, respectively. Furthermore, it was confirmed that the shear strengths improved to 51.6 MPa and 57.0 MPa by increasing the Ge content to 3.0 mass% and 5.0 mass%.

[0221] On the other hand, for the addition of Ni evaluated as a comparative example, the addition of 0.01 mass% showed a shear strength of 53.9 MPa, but it was confirmed that as the addition amount was increased to 0.10 mass% and 1.00 mass%, the shear strength decreased to 37.1 MPa and 28.6 MPa.

[0222] Thus, according to the findings obtained in Example 4, it was confirmed that the ZnAl eutectoid alloy bonding material of the present invention exhibits a high shear strength of over 90 MPa even when bonded at a low temperature of 350°C by adding approximately 1.0 mass% Ge as an additive element. It was also confirmed that, when the bonding temperature is 400°C, a shear strength of over 50 MPa can be stably obtained by adding 3.0 to 5.0 mass% Ge. In contrast, it was confirmed that the shear strength remains at 17 to 30 MPa when V is added in an amount ranging from 0.01 to 0.1 mass%. It was also confirmed that, although a small amount of Ni (0.01 mass%) provides a certain effect, the shear strength tends to decrease as the amount added increases.

[0223] Furthermore, it was confirmed that the ZnAl eutectoid alloy bonding material of the present invention can obtain practical shear strength even with the basic composition by appropriately setting the bonding temperature and holding time. These results show that the ZnAl eutectoid alloy bonding material of the present invention has excellent properties as a practical bonding material that can shorten the holding time by adding Ge and achieve stable shear strength.

[0224] The present invention is not limited to the above-described embodiments and variations thereof, and other embodiments may be possible within the scope of the teachings and spirit of the present invention without departing from the spirit and scope of the present invention. The components of the above-described embodiments may be arbitrarily selected and combined. Furthermore, any component of the embodiment may be arbitrarily combined with any component described in the Summary of the Problems or any component embodying any component described in the Summary of the Problems. The present invention intends to obtain rights to these as well through amendments to this application or divisional applications, etc.

[0225] The method for producing a ZnAl eutectoid alloy bonding material of the present invention can be suitably used in producing a ZnAl eutectoid alloy bonding material that can be used in place of lead-containing solder as a bonding material for devices, etc. that operate under high temperature conditions. Furthermore, the bonded body of the present invention can be suitably used as a component of devices, etc. that operate under high temperature conditions. The method for producing a bonded body of the present invention can be suitably used in producing a bonded body required for producing devices, etc. that operate under high temperature conditions.

[0226] 10: Manufacturing apparatus 20: Main body 24: Introduction section 26: Discharge section 30: Gas supply source 40: Oxygen concentration measuring device 50: Pressurizing device 52: First clamping section 54: Second clamping section 56: Installation section 60: Heating device 62: Heating element 64: Heating element 66: Temperature measuring device 68: Heating control device

Claims

1. A ZnAl eutectoid alloy bonding material comprising a ZnAl eutectoid alloy with a basic composition of Zn and Al, characterized in that it contains Al in the range of 25% by mass to 28% by mass, with the remainder being Zn and inevitable impurities.

2. A ZnAl eutectoid alloy joining material according to claim 1, characterized in that the basic composition further contains either or both of Cu in a range of less than 2.0 mass% and Mg in a range of less than 2.0 mass%.

3. A ZnAl eutectoid alloy joining material according to claim 1 or 2, characterized in that the solidus temperature is 450°C or less.

4. A ZnAl eutectoid alloy joining material according to claim 1 or 2, characterized in that the difference between the liquidus temperature and the solidus temperature is 50°C or more and 150°C or less.

5. A joint comprising a substrate and a joint comprising a ZnAl eutectoid alloy joint material, wherein the ZnAl eutectoid alloy joint material has a basic composition of Zn and Al, containing Al in the range of 25% by mass to 28% by mass, with the remainder being Zn and unavoidable impurities.

6. The joined body according to claim 5, characterized in that the ZnAl eutectoid alloy joining material further contains, as the basic composition, either or both of Cu in a range of less than 2.0 mass% and Mg in a range of less than 2.0 mass%.

7. A joined body according to claim 5 or 6, characterized in that the joint is formed by joining an object to be joined to the base material via the ZnAl eutectoid alloy joining material disposed between the object to be joined and the base material, and the amount of the ZnAl eutectoid alloy joining material protruding from the outer edge of the object to be joined at the joint is 3 mm or less.

8. A joint as claimed in claim 5 or 6, characterized in that the solidus temperature of the ZnAl eutectoid alloy joint material is 450°C or lower.

9. A joint as claimed in claim 5 or 6, characterized in that the difference between the liquidus temperature and the solidus temperature of the ZnAl eutectoid alloy joint material is 50°C or more and 150°C or less.

10. A method for manufacturing a bonded body having a bonded portion comprising a substrate and a ZnAl eutectoid alloy bonding material, wherein the ZnAl eutectoid alloy bonding material has a basic composition of Zn and Al, containing 25% to 28% by mass of Al, with the remainder containing Zn and inevitable impurities, and the method comprises: an adhesion improving step of contacting the substrate and the ZnAl eutectoid alloy bonding material and applying pressure to improve the adhesion between the substrate and the ZnAl eutectoid alloy bonding material; and a bonding step of bonding the substrate and the ZnAl eutectoid alloy bonding material, which have been brought into contact in the adhesion improving step, by heating them under temperature conditions that allow bonding.

11. A method for manufacturing a bonded body according to claim 10, characterized in that at least the bonding step is carried out in an atmosphere with an oxygen concentration of 30 ppm or less.

12. A method for manufacturing a bonded body as described in claim 10 or 11, characterized in that in the adhesion improvement process, the pressure applied to the base material and the bonding material is increased at a rate lower than 1 mm / min.

13. A method for manufacturing a bonded body as described in claim 10 or 11, characterized in that the adhesion improvement process involves performing a preheat treatment in which pressure is applied to the base material and the bonding material at a temperature lower than the bonding temperature at which bonding is possible in the bonding process and higher than room temperature.

14. A method for manufacturing a bonded body as described in claim 13, characterized in that, when the pressure applied to the base material and the bonding material in the bonding process is a bonding pressure, the pressure applied to the base material and the bonding material in the preheat treatment is a preheat pressure that is lower than the bonding pressure.

15. A method for manufacturing a bonded body according to claim 10 or 11, characterized in that after the adhesion improving process, a temperature raising process is carried out in the bonding process to raise the temperature to a temperature condition that enables bonding, and in the temperature raising process, the temperature of the atmosphere to which the base material and the bonding material are exposed is continuously raised.

16. A method for manufacturing a bonded body as described in claim 10 or 11, characterized in that in a step subsequent to the adhesion improvement step, the pressure applied to the substrate and the bonding material during the period in which the substrate and the bonding material are heated is reduced.

17. A ZnAl eutectoid alloy bonding material comprising a ZnAl eutectoid alloy having a basic composition of Zn and Al, characterized in that it contains Al in the range of 20 mass% to 30 mass% and at least one additive element selected from the group consisting of Ag, Co, Ge, Mn, Mo, Ni, Sb, and V in the range of 0.001 mass% to 2.0 mass%, with the remainder being Zn and inevitable impurities.

18. The ZnAl eutectoid alloy joining material according to claim 17, characterized in that the additional element is selected from the group consisting of Ge, Mn, Ni, and V.

19. A ZnAl eutectoid alloy joining material comprising a ZnAl eutectoid alloy having a basic composition of Zn and Al, containing Ge in the range of 1.0 mass% to 5.0 mass% with the remainder being Zn and inevitable impurities, and exhibiting a shear strength of 40 MPa or more when joined at 350°C.

20. A joint comprising a substrate and a joint comprising a ZnAl eutectoid alloy joining material, wherein the ZnAl eutectoid alloy joining material is the ZnAl eutectoid alloy joining material defined in claim 17 or 18.

21. The joint body according to claim 20, wherein the substrate is a copper substrate or a low-phosphorus Ni-plated substrate.

22. A bonded body using the ZnAl eutectoid alloy bonding material according to claim 19, characterized in that the substrate is a copper substrate or a Ni-plated substrate.

23. A method for manufacturing a bonded body having a bonded portion comprising a substrate and a ZnAl eutectoid alloy bonding material, wherein the ZnAl eutectoid alloy bonding material according to claim 17 or 18 is used as the ZnAl eutectoid alloy bonding material, the method comprising: an adhesion improving step of contacting the substrate and the ZnAl eutectoid alloy bonding material while applying pressure, thereby improving the adhesion between the substrate and the ZnAl eutectoid alloy bonding material; and a bonding step of bonding the substrate and the ZnAl eutectoid alloy bonding material that have been brought into contact in the adhesion improving step by heating them under temperature conditions that allow bonding.

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