TW202132032A - Metal bonding material - Google Patents

Abstract

A metal bonding material according to an embodiment of the present invention is formed by bonding a first metal member and a second metal member. The first metal member and the second metal member are bonded with a diffusion layer interposed therebetween. In a cross section perpendicular to the diffusion layer, only the first metal member, of the first metal member and the second metal member, has a first columnar crystal structure part that is adjacent to the diffusion layer and includes a plurality of crystal grains extending in a direction away from the diffusion layer.

Description

Metal bonding material

This disclosure relates to a metal bonding material.

Since the past, the technology of joining metal parts to each other has been used in various fields.

In addition, in recent years, the requirements for materials have become stricter year by year. In addition to the pursuit of technology to join metal parts of the same material to each other, technology to join metal parts of dissimilar materials to each other is also pursued, and in particular, dissimilar metals with opposite characteristics are pursued. The high precision of the joining of parts.

For example, a heat exchanger that combines a material with high thermal conductivity, that is, a copper-based component or an aluminum-based component, and a stainless steel component or heat-resistant steel component with high heat resistance, and a copper-based component with a large specific gravity and an aluminum-based component with a small specific gravity. Combinations, etc., have high requirements for the diversity of the metal parts constituting the metal joining material. In particular, as an example of the practical application of various types of bonding materials, in bimetal, metal parts with different thermal expansion coefficients are bonded to each other, and in shunt resistors, metal parts with low resistivity are connected to each other. High rate of joining of metal parts.

As a joining method of metal parts, there are fusion welding, solid-state joining, brazing, bonding, mechanical joining, and the like. Among them, the joining method of metal parts by fusion welding has been used since ancient times, and it is practical and has many practical results. As far as fusion welding is concerned, there are tungsten inert gas welding (TIG welding), metal inert gas welding (MIG Welding), and metal-arc active gas welding (metal-arc active gas welding, Arc welding such as MAG welding and plasma welding; resistance welding such as spot welding, seam welding, projection welding, and flash-butt welding; electron beam Welding (electron beam welding) such as high-energy beam welding, etc.

For example, Patent Document 1 describes a dissimilar metal joint that joins an aluminum-based metal material and an iron-based metal material coated with at least a part of the surface of zinc, and the iron-based metal material and the aluminum-based metal material are bonded together. An alloy layer in which zinc is solid-dissolved in aluminum is interposed at the interface. Further, in the aforementioned alloy layer, zinc is precipitated, and in the aforementioned alloy layer, a layer consisting of iron, aluminum, and zinc is dispersed and precipitated. An intermetallic compound composed of more than two metal elements in the group. In Patent Document 1, the method of manufacturing a dissimilar metal joint includes: a first step of irradiating a joint between an aluminum-based metal material and an iron-based metal material with laser light to make the zinc contained on the surface of the iron-based metal material, and The aluminum contained in the surface of the aluminum-based metal material is eluted; and, the second step is to press a roller toward the direction in which the laser light irradiation surfaces contact each other, and at the interface between the iron-based metal material and the aluminum-based metal material, Forms an alloy layer in which zinc is solid-soluble in aluminum.

In addition, Patent Document 2 describes a butt-joining method of dissimilar metals by butting the end faces of a metal mainly composed of copper and zinc and a metal mainly composed of iron to form a butting interface, and the butt joint A beam with a high energy density is irradiated near the interface to form a junction, and the aforementioned metal containing copper and zinc as the main components and the aforementioned metal containing iron as the main component are joined through (via) the junction. Here, a dissimilar metal In the butt bonding method, the position of the irradiation center of the light beam with high energy density is set to be away from the butting interface and on the surface of the metal containing copper and zinc as main components, and will be adjacent to the copper and zinc The part of the abutting interface of the metal as the main component is melted to form the joint composed of the molten structure of the metal having copper and zinc as the main components. In Patent Document 2, a metal with copper and zinc as the main components is irradiated with a light beam. The metal with copper and zinc as the main components has a higher thermal conductivity and laser light absorption than a metal with iron as the main component. The rate is lower.

In the above-mentioned prior art, like aluminum-based metal parts and iron-based metal parts, or metal parts with copper and zinc as main components, and metal parts with iron as the main components, metal joining materials are limited to specific combinations of metal parts. In addition, because high-temperature cracking is prone to occur, the forming process is not easy, and the joining properties such as tensile strength are insufficient. Furthermore, with the improvement of the technical level in recent years, further improvement of the bonding characteristics of metal bonding materials is pursued. [Prior Technical Literature] (Patent Document)

Patent Document 1: Japanese Patent No. 5165339 Patent Document 2: Japanese Patent Laid-Open No. 2013-154398

[The problem to be solved by the invention] The purpose of the present disclosure is to provide a metal joining material that has excellent joining reliability between the metal parts regardless of whether it is a metal part of the same system material or a metal part of a different system material.

[Technical means used to solve the problem] [1] A metal joining material formed by joining a first metal part and a second metal part, the metal joining material is characterized in that: the first metal part and the second metal part are joined via a diffusion layer; In the cross section of the diffusion layer, among the first metal component and the second metal component, only the first metal component has a first columnar crystal structure portion, and the first columnar crystal structure portion is adjacent to the diffusion layer And it includes a plurality of crystal grains extending in a direction away from the aforementioned diffusion layer. [2] The metal joining material according to the above [1], wherein, in the cross section, among all the crystal grains in the first columnar crystal structure portion, there are a plurality of crystal grains having an aspect ratio of 0.50 or less The occupied area ratio is 50% or more. [3] The metal bonding material according to the above [1] or [2], wherein in the cross section, the average thickness of the first columnar crystal structure portion is 50 micrometers (μm) or more and 500 μm or less. [4] A metal joining material formed by joining a first metal member and a second metal member, wherein: the first metal member and the second metal member are joined via a diffusion layer, and the average thickness of the diffusion layer is 50 μm the following. [5] The metal joining material according to any one of the above [1] to [4], wherein, in the cross section, the first metal member is on the diffusion layer side of the first columnar crystal structure part There is a second columnar crystal structure portion on the opposite side of, and the second columnar crystal structure portion includes a plurality of crystal grains extending in a direction away from the first columnar crystal structure portion. [6] The metal joining material according to the above [5], wherein, in the cross section, the first metal member has a side between the first columnar crystal structure portion and the second columnar crystal structure portion interface. [7] The metal joining material according to the above [6], wherein, in the cross section, the direction from the boundary surface, parallel to the boundary surface, and from the boundary surface to the side opposite to the second metal member side In the first region divided by the first reference line with a direction away from 400 μm and the two outline lines of the first metal component, the area ratio of the crystal grains having an aspect ratio of 0.35 or less is 50% or more. [8] The metal joining material according to any one of [1] to [7] above, wherein at 25° C., the thermal conductivity λ2 of the second metal member is relative to the thermal conductivity λ1 of the first metal member The ratio (λ2/λ1) is 10 or more, and the difference ΔT between the melting point T1 of the first metal component and the melting point T2 of the second metal component is 10°C or more. [9] The metal joining material according to any one of the above [1] to [8], wherein the first metal member is an aluminum-based material, and the second metal member is a copper-based material. [10] The metal joining material according to any one of the above [1] to [8], wherein the first metal member is an iron-based material, and the second metal member is a copper-based material. [11] The metal joining material according to any one of [1] to [8] above, wherein the first metal member and the second metal member are aluminum-based materials. [12] The metal joining material according to any one of [1] to [8] above, wherein the first metal member and the second metal member are iron-based materials. [13] The metal joining material according to any one of the above [1] to [8], wherein the first metal member and the second metal member are copper-based materials. [14] The metal joining material according to any one of the above [1] to [8], wherein the first metal member is a copper alloy material for resistance material, and the second metal member has a conductivity higher than that of the first metal member. Copper-based materials with higher metal parts. [15] The metal joining material according to the above [14], wherein the first metal member is a copper alloy material for resistance material, and the copper alloy material for resistance material has an alloy composition, and the alloy composition contains 10.0% by mass or more And 14.0% by mass or less of manganese (Mn), 1.0% by mass or more and 3.0% by mass or less of nickel (Ni), the remainder is composed of copper (Cu) and unavoidable impurities. [16] The metal joining material according to the above [14], wherein the first metal member is a copper alloy material for resistance material, the copper alloy material for resistance material has an alloy composition, and the alloy composition contains 6.0% by mass or more And 8.0 mass% or less of Mn, 2.0 mass% or more and 4.0 mass% or less of tin (Sn), the remainder is composed of Cu and unavoidable impurities.

[Effect of Invention] According to the present disclosure, it is possible to provide a metal joining material that has excellent joining reliability between metal parts regardless of whether it is a metal part of the same system material or a metal part of a different system material.

Hereinafter, the embodiments will be described in detail.

The inventors of this case have repeated their in-depth investigations and found that by seeking to optimize the bonding conditions of optical fiber laser welding and the physical properties of metal parts, a metal joining material can be obtained, whether it is a metal part of the same material or a metal of a dissimilar material. The joint reliability of the parts and the metal parts is excellent, and the invention of the present disclosure has been completed based on this knowledge.

Fig. 1 is a perspective view showing the outline of the metal bonding material 1 of the embodiment. FIG. 2 is an image obtained by observing the cross section of the diffusion layer 30 perpendicular to the metal bonding material 1 by using the EBSD method. Specifically, FIG. 2 is an image of a cross section each perpendicular to the diffusion layer 30 of the metal bonding material 1 and the irradiation direction of the laser light. Fig. 3 is a schematic diagram showing each structure in the image of Fig. 2. The metal joining material 1 is formed by joining the first metal component 10 and the second metal component 20.

First, regarding the first metal member 10 and the second metal member 20 constituting the metal joining material 1, the materials and their combination will be described.

As a material and a combination of the first metal member 10 and the second metal member 20, the metal joining material 1 may have a first columnar crystal structure portion 12 and a diffusion layer 30 described later.

Regarding the combination of materials constituting the first metal component 10 and the second metal component 20, they may be materials of different series or materials of the same series. Here, the dissimilar material means that it contains different metals, that is, dissimilar metals, different alloys, that is, dissimilar alloys, and different alloy systems, that is, dissimilar alloys. In addition, the homologous material means the same metal, that is, the same metal, the same alloy, that is the same alloy, and the same alloy system, that is the same alloy.

For example, when the combination of the first metal component 10 and the second metal component 20 is a dissimilar material, as the material and combination constituting the first metal component 10 and the second metal component 20, it is preferable that the first metal component 10 is A combination of aluminum-based materials and the second metal component 20 is a combination of copper-based materials, the first metal component 10 is a combination of iron-based materials, and the second metal component 20 is a combination of copper-based materials. The metal joining material 1 formed by using such a combination of dissimilar materials can be easily manufactured by optical fiber laser welding described later, and has excellent joining properties such as tensile strength and elongation.

In addition, when the combination of the first metal component 10 and the second metal component 20 is the same series of materials, the materials constituting the first metal component 10 and the second metal component 20 are preferably aluminum-based materials, iron-based materials, and copper. Department of materials. The metal joining material 1 composed of the combination of the same series of materials can be easily manufactured by optical fiber laser welding, and has excellent joining properties such as tensile strength and elongation.

In addition, among the materials of the same series, the metal bonding material 1 constituted by the combination of the first metal member 10 and the second metal member 20 shown below is suitable for use as a resistor such as a shunt resistor. As a metal bonding material 1 suitable for a resistor, the first metal member 10 is a copper alloy material for resistance material shown below, and the second metal member is a copper-based material with a higher conductivity than the first metal member 10. More preferably, the second metal part is pure copper.

The copper alloy material for the resistance material pursues electrical characteristics such as a large specific resistance and a small temperature coefficient of resistance change. Therefore, a copper alloy containing 30.0% by mass or less of manganese (Mn) can be used.

In particular, as a copper alloy material for resistance materials, it is a copper-manganese-nickel (Cu-Mn-Ni) series copper alloy material for resistance materials, which has an alloy composition containing 10.0% by mass or more and 14.0% by mass. % Of Mn or less, 1.0% by mass or more and 3.0% by mass or less of nickel (Ni), the remainder is composed of copper (Cu) and unavoidable impurities.

As another type of copper alloy material for resistance materials, it is a copper-manganese-tin (Cu-Mn-Sn) series copper alloy material for resistance materials, which has an alloy composition containing 6.0% by mass or more and 8.0% by mass % Or less of Mn, 2.0% by mass or more and 4.0% by mass or less of tin (Sn), the remainder is composed of Cu and unavoidable impurities.

The above-mentioned Cu-Mn-Ni series and Cu-Mn-Sn series of copper alloy materials for resistance materials, the absolute value of the temperature coefficient of resistance in the temperature range of 20°C or more and 50°C or less is 50ppm/°C or less, and the temperature coefficient of resistance It is small, and the resistance value is stable even if the ambient temperature changes, so it is suitable for resistance materials used in resistors.

The temperature coefficient of resistance (TCR) means the ratio of the change in resistance value per 1°C temperature difference and is expressed by the following formula (1).

Temperature Coefficient of Resistance (TCR) (unit: ppm/℃)={(RR ₀ )/R ₀ }×[1/{(TT ₀ )×10 ⁶ }] …Equation (1)

In formula (1), T represents the test temperature (unit: ℃), T ₀ represents the reference temperature (unit: ℃), R represents the resistance value at the test temperature T (unit: Ω), R ₀ represents the reference temperature T _{Resistance value in 0} (unit: Ω).

Regarding the above-mentioned copper alloy material for Cu-Mn-Ni resistance material, if the Mn content is less than 10.0% by mass, the temperature coefficient of resistance will increase and the grain size during recrystallization annealing will increase. If the content of Mn exceeds 14.0% by mass, the resistivity increases, the crystal grain size during recrystallization annealing decreases, and the corrosion resistance and manufacturability decrease. In addition, if the Ni content is less than 1.0% by mass, the temperature coefficient of resistance increases, the crystal grain size during recrystallization annealing increases, and the corrosion resistance decreases. If the Ni content exceeds 3.0% by mass, the resistivity increases, the crystal grain size during recrystallization annealing decreases, and the manufacturability decreases.

Regarding the above-mentioned copper alloy material for the Cu-Mn-Sn resistor material, if the Mn content is less than 6.0% by mass, the temperature coefficient of resistance will increase and the crystal grain size during recrystallization annealing will increase. If the content of Mn exceeds 8.0% by mass, an increase in resistivity and a decrease in crystal grain size during recrystallization annealing will occur. In addition, if the content of Sn is less than 2.0% by mass, the temperature coefficient of resistance increases, the crystal grain size during recrystallization annealing increases, and the corrosion resistance decreases. If the Sn content exceeds 4.0% by mass, the resistivity increases, the crystal grain size during recrystallization annealing decreases, and the manufacturability decreases.

In addition, the copper alloy material for the aforementioned Cu-Mn-Ni series and Cu-Mn-Sn series resistance materials preferably further contains one or more elements selected from the group consisting of the following elements: 0.001% by mass or more and 0.500% by mass or less of iron (Fe), 0.001% by mass or more and 0.100% by mass or less of silicon (Si), 0.001% by mass or more and 0.500% by mass or less of chromium (Cr), 0.001% by mass or more and 0.200% by mass or less Zirconium (Zr), 0.001% by mass or more and 0.200% by mass or less of titanium (Ti), 0.001% by mass or more and 0.500% by mass or less of silver (Ag), 0.001% by mass or more and 0.500% by mass or less of magnesium (Mg), 0.001% by mass or more and 0.100% by mass or less of cobalt (Co), 0.001% by mass or more and 0.100% by mass or less of phosphorus (P), and 0.001% by mass or more and 0.500% by mass or less of zinc (Zn).

If the above-mentioned Cu-Mn-Ni-based and Cu-Mn-Sn-based copper alloy materials for resistance materials further contain one or more of the above-mentioned elements, the crystal grain growth during recrystallization annealing will be slower, so the control of the crystal grain size will become Easy, besides, heat resistance will be improved. Therefore, the bonding characteristics of the metal bonding material 1 will be further improved.

In this way, the above-mentioned copper alloy material for a resistance material has an extremely small temperature coefficient of resistance, and is therefore suitable for use as a resistance material for a resistor that requires a change in resistance value to stabilize the ambient temperature. In addition, the metal bonding material 1 formed by bonding a copper-based material with a higher conductivity than a copper alloy material for a resistance material and a copper alloy material for a resistance material is suitable for use in resistors such as shunt resistors.

Subsequently, the structure of the metal bonding material 1 in the cross section perpendicular to the diffusion layer 30 will be described.

As shown in FIGS. 1 to 3, the metal joining material 1 is formed by joining the first metal member 10 and the second metal member 20 with the diffusion layer 30 interposed therebetween. In the cross section perpendicular to the diffusion layer 30, among the first metal component 10 and the second metal component 20, only the first metal component 10 has a first columnar crystal structure portion 12, and the first columnar crystal structure portion 12 includes Toward a plurality of crystal grains 11 extending away from the diffusion layer 30. The first columnar crystal structure portion 12 is adjacent to the diffusion layer 30 on the side of the first metal member 10.

The diffusion layer 30 is formed between the first metal component 10 and the second metal component 20. The metal element constituting the diffusion layer 30 is composed of the metal element constituting the first metal component 10 and the metal element constituting the second metal component 20.

The first columnar crystal structure portion 12 includes a large number of crystal grains 11 that extend from the diffusion layer 30 toward the first metal component 10 and extend along the joining direction X as a whole. Compared with the crystal grains of the structure of the first metal component 10 before joining, the crystal grains 11 are elongated. In addition, the state of the first columnar crystal structure portion 12 in the joining direction X may be a state in which the crystal grains 11 are formed on the entire surface from the side of the diffusion layer 30 to the second columnar crystal structure portion 14 described later. It may be a state in which the crystal grains 11 are partially formed, or these states may be mixed as shown in FIGS. 2 to 3.

Since the metal joining material 1 has the first columnar crystal structure portion 12 in the first metal component 10, the tensile strength and elongation of the first metal component 10 can be improved. Furthermore, since the first columnar crystal structure part 12 in the first metal component 10 is adjacent to the diffusion layer 30, the first columnar crystal structure part 12 is joined to the diffusion layer 30. Therefore, even if the average thickness of the diffusion layer 30 is smaller than in the past, the bonding strength between the first metal member 10 and the second metal member 20 is good, so the metal bonding material 1 has excellent bonding properties such as tensile strength and elongation. Furthermore, the average thickness of the diffusion layer 30 whose resistance value is more unstable than that of the first metal member 10 and the second metal member 20 can be reduced and made uniform. Therefore, when the metal bonding material 1 is a resistor, it can be as described later. The dispersion of the resistance value and the resistance temperature coefficient of each metal bonding material 1 is suppressed.

In addition, the crystal grains 11 in the first columnar crystal structure portion 12 are preferably formed as shown in FIGS. 2 to 3 and formed continuously over the entire surface of the bonding surface direction Y in the metal bonding material 1. If a plurality of crystal grains 11 continue to be formed over the entire surface of the bonding surface direction Y, even if the average thickness of the diffusion layer 30 is further reduced, the bonding strength of the first metal component 10 and the second metal component 20 will increase, so the metal bonding material The bonding characteristics of 1 will be further improved.

In addition, it is preferable that at least a part of the plurality of crystal grains 11 included in the first columnar crystal structure portion 12 penetrate the diffusion layer 30 and extend to the second metal in the cross-sections shown in FIGS. 2 to 3 Part 20. If at least a part of the crystal grains 11 included in the first columnar crystal structure portion 12 penetrates the diffusion layer 30 and extends to the second metal component 20, the crystal grains 11 in the first columnar crystal structure portion 12 will interact with the second metal component. Therefore, even if the average thickness of the diffusion layer 30 is further reduced, the bonding strength of the first metal component 10 and the second metal component 20 will be further increased, and the bonding characteristics of the metal bonding material 1 will be further improved.

The die 11 penetrates the diffusion layer 30 and extends to the second metal component 20 means that in the cross section shown in FIGS. 2 to 3, the die 11 penetrates the diffusion layer 30 and penetrates into the second metal component 20.

The crystal grains 11 that have not penetrated into the diffusion layer 30 are composed of the same metal element as the metal element constituting the first metal component 10. In addition, for the portion of the crystal grain 11 that has penetrated into the diffusion layer 30 and that has penetrated into the diffusion layer 30, it is composed of the same metal element as the metal element constituting the diffusion layer 30, that is, the metal element constituting the first metal component 10 and the second metal element. The metal element of the metal component 20 is composed of the part that does not penetrate the diffusion layer 30, that is, the part from the diffusion layer 30 to the side of the first metal component 10, which is composed of the same metal element as the metal element constituting the first metal component 10. In addition, the portion of the crystal grain 11 that penetrates the diffusion layer 30 and extends to the second metal component 20 and penetrates into the second metal component 20 is composed of the same metal element as the metal element constituting the second metal component 20 and penetrates into The part of the diffusion layer 30 is composed of the same metal element as the metal element constituting the diffusion layer 30, and the part that does not penetrate into the diffusion layer 30 is composed of the same metal element as the metal element constituting the first metal member 10.

In addition, in the cross-sections shown in FIGS. 2 to 3, all the crystal grains in the first columnar crystal structure portion 12 have an aspect ratio (short-side direction) of 0.50 or less (more than 0 and less than 0.50). The ratio of the area occupied by a plurality of crystal grains of the size/long-side direction size) is preferably 50% or more, more preferably 80% or more, and still more preferably 90% or more. In this way, if the area ratio of a plurality of crystal grains having an aspect ratio of 0.50 or less occupies more than 50% of the first columnar crystal structure portion 12, the length of the first columnar crystal structure portion 12 The content ratio of the crystal grains 11 having an aspect ratio of 0.50 or less increases, so the above-mentioned characteristics of the first columnar crystal structure portion 12 will be further improved. As a result, even if the average thickness of the diffusion layer 30 is further reduced, the bonding strength of the first metal member 10 and the second metal member 20 will be further increased, and the bonding characteristics of the metal bonding material 1 will be further improved.

The aspect ratio of the crystal grain is the ratio of the size in the short-side direction of the crystal grain to the size in the long-side direction. In the cross-sections shown in Figures 2 to 3, the long-side dimension of the crystal grain means the maximum dimension of the crystal grain in the joining direction X, and the short-side dimension of the crystal grain means the direction perpendicular to the joining direction X The maximum size of the crystal grain. In the case of truly round crystal grains, the aspect ratio is 1.

For example, regarding the crystal grain 11, the dimension in the longitudinal direction is approximately 20 μm or more and 400 μm or less, and the dimension in the short side direction is approximately 1 μm or more and 80 μm or less.

The structure of the metal bonding material 1 in the cross section perpendicular to the diffusion layer 30 as shown in FIGS. 2 to 3 can be obtained by using a high resolution scanning electron microscope (Japan The EBSD detector attached to Electronics Co., Ltd., JSM-7001FA) continuously measures the obtained crystal orientation data, and uses the crystal orientation analysis data calculated by the analysis software (TSL Corporation, OIM Analysis). "EBSD" means: Electron BackScatter Diffraction (Electron BackScatter Diffraction) abbreviation, which is used in a scanning electron microscope (SEM) to use the reflected electron Kikuchi line generated when the sample, that is, the metal bonding material 1 is irradiated with an electron beam Diffraction crystal orientation analysis technology. "OIM Analysis" means: data analysis software measured by EBSD. The observation sample is for the cross section perpendicular to the diffusion layer 30, and the surface after mirror finishing is made by electrolytic polishing. The observation was performed with a step size of 2.0 μm in a field of view of 3 mm in the bonding direction × 3 mm in the bonding surface direction. The azimuth difference of 15° or more is regarded as the grain boundary, and the crystal grain composed of 2 pixels or more is regarded as the analysis object.

In addition, in the cross-sections shown in FIGS. 2 to 3, the lower limit of the average thickness of the first columnar crystal structure portion 12 extending in the direction away from the diffusion layer 30 is preferably 50 μm or more, and more It is preferably 100 μm or more, more preferably 150 μm or more, and the upper limit is preferably 500 μm or less, more preferably 400 μm or less, and still more preferably 350 μm or less. The average thickness of the first columnar crystal structure portion 12 means the average length dimension along the joining direction X in the cross-sections shown in FIGS. 2 to 3. If the average thickness of the first columnar crystalline structure portion 12 is 50 μm or more, the mechanical strength of the first metal component 10 having the first columnar crystalline structure portion 12 will increase, and therefore the bonding characteristics of the metal bonding material 1 will be further improved. In addition, if the average thickness of the first columnar crystal structure portion 12 is 500 μm or less, the coarsening of the crystal size of the first columnar crystal structure portion 12 is suppressed, and the first columnar crystal structure portion 12 having the first columnar crystal structure portion 12 is suppressed from coarsening. The mechanical strength of a metal component 10 is reduced, so the bonding characteristics of the metal bonding material 1 will be good.

Here, in the cross-sectional image perpendicular to the diffusion layer, 10 locations of the diffusion layer specified by the EPMA line analysis of the diffusion layer 30 described later are connected, thereby specifying the diffusion layer 30 and the first columnar shape. The boundary of the crystalline structure part 12. In addition, as shown in FIG. 2, by observing the cross section perpendicular to the diffusion layer by using the EBSD method, the boundary surface 15 separating the first columnar crystal structure portion 12 and the second columnar crystal structure portion 14 can be specified. By these two boundaries, the area of the first columnar crystal structure portion 12 is specified.

The average thickness of the first columnar crystalline structure portion 12 is the following value: Observe the five cross-sections perpendicular to the diffusion layer 30 shown in Figs. 2 to 3, and measure the first columnar in each cross-section. The maximum thickness and minimum thickness of the crystalline structure part 12 are calculated (the maximum thickness of the first columnar crystalline structure part 12 + the minimum thickness of the first columnar crystalline structure part 12)/2, and the total value is divided by 5.的值。 The value.

In addition, in the cross-sections shown in FIGS. 2 to 3, the average thickness of the diffusion layer 30 formed between the first metal member 10 and the second metal member 20 is 50 μm or less, preferably 40 μm or less, More preferably, it is 30 μm or less. In this way, the average thickness of the diffusion layer 30 is 50 μm or less, and the smaller the better. The average thickness of the diffusion layer 30 is the average length dimension obtained along the joining direction X in the cross section shown in FIGS. 2 to 3. If the average thickness of the diffusion layer 30 is 50 μm or less, the average thickness is smaller than before, so the bonding strength of the first metal member 10 and the second metal member 20 is good, and the bonding characteristics of the metal bonding material 1 are excellent.

In addition, in electronic equipment and electrical equipment assembled by using the metal bonding material 1 as a resistor, the miniaturization of the metal bonding material 1 has been promoted with the high integration in recent years. In the past, due to the large average thickness of the diffusion layer 30 and uneven thickness of the diffusion layer in miniaturized metal bonding materials, the bonding state of the first metal part and the second metal part was unstable, so the electrical resistance of each metal bonding material The value and the temperature coefficient of resistance will become unstable. In the embodiment, as described above, the average thickness of the diffusion layer 30 of the metal joining material 1 is smaller and more uniform than before, so the joining state of the first metal component 10 and the second metal component 20 is stabilized, and The dispersion of the resistance value and the temperature coefficient of resistance of each metal bonding material 1 can be suppressed. In addition, from the viewpoint of the bonding strength of the first metal member 10 and the second metal member 20, the lower limit of the average thickness of the diffusion layer 30 is, for example, 1 μm or more.

The diffusion layer 30 is specified by EPMA line analysis. The average thickness of the diffusion layer 30 is measured at 10 locations in the line analysis of EPMA in the cross-sectional images perpendicular to the diffusion layer 30 shown in FIGS. 2 to 3, and the average value is calculated. Figure 4 is the EPMA line analysis result of the image in Figure 2. In the analysis result shown in Fig. 4, the average thickness of the diffusion layer 30 is 21 μm.

In addition, it is preferable that in the cross-sections shown in FIGS. 2 to 3, among the first metal member 10 and the second metal member 20, only the first metal member 10 is in the first columnar crystal structure portion 12 On the opposite side of the diffusion layer 30 side, there is a second columnar crystal structure portion 14 including a plurality of crystal grains 13 extending in a direction away from the first columnar crystal structure portion 12 . The side opposite to the diffusion layer 30 side of the first columnar crystal structure portion 12 means the first metal member 10 side of the first columnar crystal structure portion 12. The second columnar crystal structure portion 14 is adjacent to the first columnar crystal structure portion 12 on the side of the first metal member 10.

The second columnar crystal structure portion 14 is composed of the same metal element as the metal element constituting the first metal member 10. That is, the crystal grains 13 contained in a large number of the second columnar crystal structure portion 14 are composed of the same metal element as the metal element constituting the first metal component 10. The second columnar crystal structure portion 14 includes a large number of crystal grains 13 that extend from the first columnar crystal structure portion 12 toward the first metal member 10 and extend along the joining direction X as a whole. Compared with the crystal grains of the structure of the first metal component 10 before joining, the crystal grains 13 are elongated.

Since the metal joining material 1 has the second columnar crystal structure portion 14 in the first metal component 10, the tensile strength and elongation of the first metal component 10 can be improved. Furthermore, since the second columnar crystal structure portion 14 in the first metal component 10 is adjacent to the first columnar crystal structure portion 12, the second columnar crystal structure portion 14 and the first columnar crystal structure portion 12 are joined, Therefore, the bonding strength of the first metal component 10 and the second metal component 20 will be further increased, and the bonding characteristics of the metal bonding material 1 will be further improved. Furthermore, since the bonding strength of the first metal member 10 and the second metal member 20 is improved, the thickness of the diffusion layer 30 can be further reduced, and therefore, the dispersion of the resistance value and the temperature coefficient of resistance of each metal bonding material 1 can be further suppressed. Furthermore, the resistance adjustment of the metal bonding material 1 becomes easier and becomes unnecessary.

Here, as described above, the first metal component 10 is on the side of the first columnar crystal structure portion 12 of the second columnar crystal structure portion 14, that is, on the first columnar crystal structure portion 12 and the second columnar crystal structure portion. There is a boundary surface 15 between 14. Therefore, in the image obtained by observing the EBSD method as shown in Fig. 2, compared to the boundary on the side of the first metal member 10 showing the second columnar crystal structure portion 14, the opposite side is the second The boundary surface 15 of the columnar crystal structure portion 14 on the side of the first columnar crystal structure portion 12 is more clear.

In the cross-sections shown in Figures 2 to 3, the first reference line of 400μm is away from the boundary surface 15, parallel to the boundary surface 15, and from the boundary surface 15 to the side opposite to the second metal member 20 side. 16. In the first region 18 divided by the two outline lines 17a, 17b of the first metal component 10, the area ratio occupied by a plurality of crystal grains having an aspect ratio of 0.35 or less (more than 0 and less than 0.35) , It is preferably 50% or more, more preferably 70% or more, and still more preferably 80% or more. In this way, if the area ratio of a plurality of crystal grains having an aspect ratio of 0.35 or less occupies 50% or more of the first region 18, the second columnar crystal structure portion 14 contains crystals having an aspect ratio of 0.35 or less. The content ratio of the grains 13 will increase, so the above-mentioned characteristics of the second columnar crystal structure part 14 will be further improved. As a result, even if the average thickness of the diffusion layer 30 is further reduced, the bonding strength of the first metal member 10 and the second metal member 20 will be further increased, and the bonding characteristics of the metal bonding material 1 will be further improved.

In the cross-sections shown in FIGS. 2 to 3, the first reference line 16 refers to a reference line parallel to the boundary surface 15 and away from the boundary surface 15 in the direction of the first metal component 10 by 400 μm. In addition, the outline lines 17a and 17b of the first metal component 10 mean two lines that extend along the joining direction X and constitute the outline of the first metal component 10. The outline lines 17 a and 17 b of the first metal component 10 extending along the joining direction X intersect the boundary surface 15 and the first reference line 16. Preferably: in the first region 18 divided by the boundary surface 15, the first reference line 16, and the two contour lines 17a, 17b, the area of a plurality of crystal grains having an aspect ratio of 0.35 or less The ratio is more than 50%.

In addition, in the cross-sections shown in FIGS. 2 to 3, among the first metal member 10 and the second metal member 20, only the second metal member 20 has a specific crystal structure portion 23, and the specific crystal structure portion 23 consists of The diffusion layer 30, the specific crystal reference line 21 parallel to the diffusion layer 30, and the two contour lines 22a, 22b of the second metal member 20 are divided, and the crystal orientation is [001] of [001] crystal structure and crystal orientation The area ratio occupied by the total area of the [011] crystal structure of [011] and the [111] crystal structure of crystal orientation [111] is 50% or more, and the area between the diffusion layer 30 and the specific crystal reference line 21 The average interval size B1 is preferably 500 μm or less.

In the cross-sections shown in FIGS. 2 to 3, the specific crystal reference line 21 means a reference line parallel to the diffusion layer 30 and away from the diffusion layer 30 in the direction of the second metal member 20. In addition, the outline lines 22a, 22b of the second metal component 20 mean two lines that extend along the joining direction X and constitute the outline of the second metal component 20. The outline lines 22 a and 22 b of the second metal component 20 extending along the joining direction X intersect the specific crystal reference line 21 and the diffusion layer 30.

The specific crystal structure part 23 includes at least a [001] crystal structure with a crystal orientation of [001], a [011] crystal structure with a crystal orientation of [011], and a [111] crystal structure with a crystal orientation of [111]. In the specific crystal structure part 23 divided by the diffusion layer 30, the specific crystal reference line 21, and the two outline lines 22a, 22b, the total of [001] crystal structure, [011] crystal structure, and [111] crystal structure The area ratio of the area is preferably 50% or more.

For the specific crystal structure part 23 whose total area occupied by the [001] crystal structure, [011] crystal structure and [111] crystal structure is 50% or more, if the average gap size B1 is 500 μm or less, the optical fiber Laser welding can easily form a good first columnar crystalline structure portion 12 and a small and uniform diffusion layer 30. Therefore, the bonding strength of the first metal component 10 and the second metal component 20 is good, and the metal bonding material 1 Excellent bonding characteristics. In addition, when the first metal member 10 is melted and solidified, internal stress and volume shrinkage are caused by its solidification and cooling. Therefore, in the vicinity of the diffusion layer 30, due to the slight creep of the second metal member 20 The creep deformation relaxes this internal stress, so the joint can be easily formed.

From the viewpoint of improving the bonding characteristics, the area ratio of the total area of the [001] crystal structure, the [011] crystal structure, and the [111] crystal structure occupied in the area of the specific crystal structure portion 23 is preferably 50 % Or more, more preferably 80% or more, still more preferably 90% or more. In addition, the average spacing size B1 between the diffusion layer 30 and the specific crystal reference line 21 is preferably 500 μm or less, more preferably 400 μm or less, and still more preferably 300 μm or less.

The crystal orientation of the specific crystal structure part 23 can be obtained by continuously measuring the crystal orientation data obtained by using a high-resolution scanning electron microscope (manufactured by JEOL Co., Ltd., JSM-7001FA) attached EBSD detector , Use analysis software (made by TSL, OIM Analysis) to calculate the crystal orientation analysis data. In addition, the average gap size B1 is the following value: Observe the 5 locations of the cross section perpendicular to the diffusion layer 30 shown in Figures 2 to 3, and measure the maximum gap size and the average gap size B1 in each cross section. For the minimum interval size, calculate (maximum interval size + minimum interval size)/2, and divide the total value by 5.

In addition, it is preferable that, in the cross-sections shown in FIGS. 2 to 3, among the first metal member 10 and the second metal member 20, only the second metal member 20 may have a twin crystal structure portion 25. The crystal structure part 25 is divided by the diffusion layer 30, the twin reference line 24 parallel to the diffusion layer 30, and the two outline lines 22a, 22b of the second metal member 20, and the area ratio occupied by the twin crystal structure is 50 % Or more, and the average spacing size B2 between the diffusion layer 30 and the twin reference line 24 is preferably 500 μm or less. When the metal bonding material 1 has the twin crystal structure portion 25, the second metal member 20 is made of a copper-based material or an iron-based material such as SUS.

In the cross-sections shown in FIGS. 2 to 3, the twin reference line 24 means a reference line parallel to the diffusion layer 30 and away from the diffusion layer 30 in the direction of the second metal component 20. The outline lines 22 a and 22 b of the second metal component 20 intersect the dual crystal reference line 24 and the diffusion layer 30. The twin crystal structure part 25 contains at least a twin crystal structure. It is preferable that the area ratio of the twin crystal structure in the twin crystal structure portion 25 divided by the diffusion layer 30, the twin crystal reference line 24, and the two outline lines 22a, 22b is 50% or more.

For the twin crystal structure part 25 where the area ratio of the twin crystal structure is 50% or more, if the average gap size B2 is 500 μm or less, a good first columnar crystal structure part 12 can be easily formed by fiber laser welding. , And the diffusion layer 30 with a small thickness and uniformity. Therefore, the bonding strength of the first metal component 10 and the second metal component 20 is good, so the bonding characteristics of the metal bonding material 1 are excellent. In addition, when the first metal member 10 is melted and solidified, internal stress and volume shrinkage are caused by its solidification and cooling. Therefore, in the vicinity of the diffusion layer 30, due to the slight creep of the second metal member 20 Deformation relaxes this internal stress, so the joint can be easily formed.

From the viewpoint of improving the bonding characteristics, the area ratio of the twin crystal structure occupied in the area of the twin crystal structure portion 25 is preferably 50% or more, more preferably 80% or more, and still more preferably 90% or more. In addition, the average spacing size B2 between the diffusion layer 30 and the twin reference line 24 is preferably 500 μm or less, more preferably 400 μm or less, and still more preferably 300 μm or less.

The twin crystal state of the twin crystal structure part 25 can be obtained by continuously measuring the crystal orientation obtained by using an EBSD detector attached to a high-resolution scanning electron microscope (manufactured by JEOL Ltd., JSM-7001FA) The data is the crystal orientation analysis data calculated by the analysis software (manufactured by TSL, OIM Analysis). In addition, the average gap size B2 is the following value: Observe the five positions of the cross section perpendicular to the diffusion layer 30 shown in Figures 2 to 3, and measure the maximum gap size and the average gap size B2 in each cross section. For the minimum interval size, calculate (maximum interval size + minimum interval size)/2, and divide the total value by 5.

In addition, at 25°C, the ratio of the thermal conductivity λ2 of the second metal component 20 to the thermal conductivity λ1 of the first metal component 10 (λ2/λ1) is preferably 10 or more, more preferably 15 or more, and furthermore It is preferably 20 or more, and the difference ΔT between the melting point T1 of the first metal component 10 and the melting point T2 of the second metal component 20 is preferably 10°C or more, more preferably 50°C or more, and still more preferably 100°C or more. Regarding the first metal component 10 and the second metal component 20 constituting the metal joining material 1, if the ratio of thermal conductivity (λ2/λ1) and the difference ΔT of melting point are within the above-mentioned numerical range, optical fiber laser welding is used to produce The metal bonding material 1 with good bonding characteristics becomes easy. In particular, the crystal grain 11, the first columnar crystal structure portion 12, the crystal grain 13, the second columnar crystal structure portion 14, the boundary surface 15, the first region 18, the specific crystal structure portion 23, the twin crystal structure portion 25, and the diffusion layer 30 are easily controlled within the above numerical range. In addition, conventionally, it has been difficult to join metal parts having a thermal conductivity ratio of 10 or higher to each other. However, by optimizing the conditions for optical fiber laser welding, it is possible to obtain a metal joining material 1 having excellent joining properties.

Subsequently, the manufacturing method of the metal bonding material 1 will be described.

The metal joining material 1 can be manufactured by joining the first metal component 10 and the second metal component 20. For the joining of the first metal part 10 and the second metal part 20, optical fiber laser welding is used.

Optical fiber laser welding is a method in which laser light is used as a heat source, the laser light is collected and irradiated to metal parts, the metal parts are partially melted and then solidified, thereby joining the metal parts to each other. Optical fiber laser welding uses high-energy-density laser light to join metal parts in a short time.

Because the lens of the optical system collects light to a very small area to obtain high-energy-density laser light, fiber laser welding has the following characteristics: high-speed deep penetration welding, minimal thermal influence of welding, and less welding distortion.

On the other hand, the high performance of light sources for optical fiber laser welding has been actively promoted in the past few years. In particular, the high output of laser light is significantly improved compared to the past.

In addition, if the metal parts are aluminum-based materials and copper-based materials, the reflectivity of the laser light of the metal parts is high, and therefore the irradiation energy of the laser light cannot be fully utilized for the melting of the metal parts, and the output of the laser light is increased. If the output of the laser light is increased, a large number of defects will be generated on the bonding surface of the metal bonding material, and therefore the connection reliability of the metal bonding material will decrease.

Based on this situation, in the embodiment, by using an optical fiber laser with an extremely high output compared to the past, and by optimizing the welding conditions, it is possible to produce a metal bonding material 1 with excellent bonding reliability.

In the embodiment, in the optical fiber laser welding, the first metal member 10 and the second metal member 20 are brought into contact with each other or the first metal member 10 and the second metal member 20 are arranged adjacent to each other. The side of the first metal member 10 is irradiated with laser light to join the first metal member 10 and the second metal member 20.

Since the laser light is irradiated to the first metal member 10, which has a lower thermal conductivity and a higher laser light absorption rate than the second metal member 20, the melting caused by the laser light is dominated by the melting of the first metal member 10. Then, by rapidly cooling after melting, the heat of the molten liquid of the first metal component 10 is transferred to the first metal component 10 and the second metal component 20 in a manner away from the irradiation position of the laser light, and at the same time, The molten part is rapidly cooled and solidified, so the above-mentioned columnar crystal structure part and the like are formed in the metal joining material 1. Furthermore, since the influence of heat transferred to the second metal member 20 can be suppressed, the thickness of the diffusion layer 30 can be made smaller and more uniform than in the past, and the specific crystal structure portion 23 and the twin crystal structure portion can be suppressed. The expansion of 25. Therefore, the bonding characteristics of the metal bonding material 1 can be improved.

Regarding the output of the laser light in the optical fiber laser welding of the first metal part 10 and the second metal part 20, the lower limit value is preferably 1kW or more, more preferably 3kW or more, and the upper limit value is preferably 10kW or less, and more Preferably, it is less than 6kW. If the output of the laser light is 1 kW or more, the melting by the laser light can be performed well. If the output of the laser light is 10 kW or less, the influence of heat transferred to the second metal member 20 can be suppressed.

According to the embodiment described above, by using a high-output optical fiber laser and optimizing the welding conditions and the physical properties of the metal parts, it is possible to obtain a metal joining material having a first columnar crystal structure part and a second columnar crystal structure. Crystal structure, etc., and has a diffusion layer with reduced thickness. Among the metal joining materials, regardless of whether the combination of the first metal part and the second metal part is a homogenous material or a dissimilar material, the joining properties such as tensile strength and elongation are good, and therefore the joining reliability of the metal parts is excellent.

The embodiments are described above, but the present invention is not limited to the above embodiments, and includes the concepts of the present disclosure and all aspects included in the scope of the patent application, and various changes can be made within the scope of the present disclosure. [Example]

Subsequently, examples and comparative examples will be described, but the present disclosure is not limited to these examples.

(Examples 1-18 and Comparative Examples 1-10) First, the first metal part and the second metal part shown in Table 1 were prepared. The first metal part and the second metal part are plate-shaped, with a thickness of 2 millimeters (mm), a width of 10 mm, and a length of 100 mm. The types of the first metal component and the second metal component are as follows.

The following are used for copper-based materials. ‧Cu-Mn-Ni series of copper alloy materials for resistance materials ‧Copper alloy materials for Cu-Mn-Sn resistance materials ‧Oxygen-free copper (OFC): Cu content is 99.96 mass% or more

The aluminum-based materials used are as follows. ‧Al1060 ‧Al7075

The iron-based materials used are as follows. ‧SUS430 ‧SUS304

[Table 1]

Then, two metal parts were selected, and the thickness of the plate was 2mm and the width was 10mm. Under the conditions shown in Table 2, the first metal part and the second metal part were welded by optical fiber laser to produce the metal joint material. . The wavelength of the laser light is 1070 nanometers (nm).

In Examples 1-18, as shown in Figure 5, the abutting surface 50 parallel to the first metal component 10 and the second metal component 20 is parallel to the contact between the first metal component 10 and the second metal component 20 For the surface method, the laser beam is irradiated while scanning at a position away from h (unit: mm) from the surface 50 to the first metal component side. That is, laser light is used to irradiate a position away from the abutting surface 50 of the first metal component 10 and the second metal component 20 by the distance h of the first metal component 10.

On the other hand, in Comparative Examples 1 to 10, instead of irradiating the first metal member 10 with laser light as in Examples 1 to 18, laser light was used to irradiate one of the first metal member 10 and the second metal member 20. Butt joint 50.

[Table 2]

For the metal bonding materials obtained in the above-mentioned examples and comparative examples, the images perpendicular to the cross-section of the diffusion layer were obtained as follows: by a high-resolution scanning electron microscope (manufactured by JEOL Co., Ltd., JSM-7001FA ) The crystal orientation data obtained by the continuous measurement of the attached EBSD detector is the crystal orientation analysis data calculated by the analysis software (manufactured by TSL, OIM Analysis). The observation sample is set as: for the cross-section perpendicular to the diffusion layer, the surface of the mirror finishing is made by electrolytic polishing. The observation was performed with a step size of 2.0 µm in a field of view of 3 mm in the bonding direction x 3 mm in the bonding surface direction. The azimuth difference of 15° or more is regarded as the grain boundary, and the crystal grain composed of 2 pixels or more is regarded as the object of analysis. Based on the image thus obtained, the results of observing the section perpendicular to the diffusion layer are shown in Table 3.

The diffusion layer is specified by EPMA line analysis. The average thickness of the diffusion layer, in the cross-sectional image perpendicular to the diffusion layer, measure 10 EPMA line analysis and make the average value.

In addition, on the cross-sectional image perpendicular to the diffusion layer, 10 locations of the diffusion layer specified by the EPMA line analysis of the diffusion layer are connected, thereby specifying the boundary between the diffusion layer and the first columnar crystal structure. In addition, the boundary surface between the first columnar crystal structure portion and the second columnar crystal structure portion is specified from the above-mentioned image perpendicular to the cross section of the diffusion layer. In this way, the region of the first columnar crystal structure is specified. Then, the average thickness of the first columnar crystalline structure was set to the following value: The area of the first columnar crystalline structure was determined by observing five cross-sections perpendicular to the diffusion layer by the above-mentioned EBSD method, and measuring the respective cross-sections Calculate the maximum thickness and minimum thickness of the first columnar crystal structure part of (maximum thickness of the first columnar crystal structure + minimum thickness of the first columnar crystal structure)/2, and divide the total value by 5. The value obtained. In addition, it is determined that a plurality of crystal grains having an aspect ratio (short-side direction size/long-side direction size) of 0.50 or less (more than 0 and 0.50 or less) among all the crystal grains in the first columnar crystal structure portion are occupied The area ratio.

In addition, it is determined that the boundary surface 15 between the first columnar crystal structure portion and the second columnar crystal structure portion is parallel to the boundary surface 15 and from the boundary surface 15 to the side opposite to the second metal member 20 side In the area occupied by the first region 18 divided by the first reference line 16 and the two outline lines 17a, 17b of the first metal component 10 in the direction of 400μm, all the crystal grains have 0.35 or less ( The ratio of the area occupied by a plurality of crystal grains with an aspect ratio (size in the short-side direction/size in the long-side direction) of more than 0 and 0.35 or less.

[table 3]

[Evaluate] With respect to the metal bonding materials obtained in the above-mentioned Examples and Comparative Examples, the following evaluations were performed. The results are shown in Table 4.

[1] Tensile strength ratio The tensile test was performed in accordance with JIS Z 2214. Then, the ratio of the tensile strength of the metal joining material to the tensile strength of the metal part with the lower tensile strength (the tensile strength of the metal joining material/the tensile strength of the metal part with the lower tensile strength) Strength) as the tensile strength ratio. In addition, when the first metal member and the second metal member are made of the same material, the metal member having the lower tensile strength is referred to as the first metal member. All metal joining materials are softened by laser heating, and the tensile strength tends to decrease compared with the metal parts before joining. However, if the tensile strength ratio is 0.80 or more, the metal joining material is judged to be good. If the tensile strength ratio is less than 0.80, the metal joining material is judged to be defective.

[2] Elongation ratio The tensile test is carried out according to JIS Z 2241. Then, the ratio of the elongation of the metal joining material to the elongation of the metal part of the lower tensile strength (elongation of the metal joining material/elongation of the metal part of the lower tensile strength) is defined as the elongation量比。 Volume ratio. All metal joining materials are softened by laser heating, and the elongation tends to increase compared to the metal parts before joining, but when the joining state is poor, the elongation will break due to the elongation. If the extension ratio is 1.5 or more, the metal joining material is judged to be good, and if the extension ratio is less than 1.5, the metal joining material is judged to be inferior.

[3] Deviation of resistance value The dispersion of the resistance value is an index for how much the resistance value of the obtained metal bonding material differs from the average value. For 10 samples of the metal joining materials obtained in Examples 1 to 11 and Comparative Examples 1 to 3, the resistance values at room temperature (25°C) were measured to obtain the measured values in each Example and each Comparative Example Average, maximum, and minimum. Then, the ratio of the difference between the maximum value and the minimum value of the resistance value of the metal bonding material to the average value of the resistance value ((the maximum value of the resistance value of the metal bonding material-the minimum value of the resistance value of the metal bonding material)/metal The average value of the bonding material) is used as the dispersion of the resistance value. The smaller the dispersion of the resistance value, the better the metal bonding material as a resistor.

[Table 4]

As shown in Tables 1 to 4, in Examples 1 to 18, in the cross section perpendicular to the diffusion layer of the metal joining material, only the first metal component has the first columnar crystal structure, and the average thickness of the diffusion layer It is less than 50µm. Therefore, the tensile strength ratio and elongation ratio of the metal joining material are good.

In addition, in Examples 1 to 11 and Comparative Examples 1 to 3, a copper alloy material for resistance material was used as the first metal member, and the tensile strength ratio, elongation ratio, and resistance value dispersion were measured. The average thickness of the diffusion layers of Examples 1 to 11 is 50 μm or less. Compared with the past, the thickness of the diffusion layer is smaller and more uniform, so that the dispersion of the resistance value can be suppressed. This suggests that the metal bonding materials of Examples 1 to 11 are suitable for resistors such as shunt resistors.

On the other hand, in Comparative Examples 1 to 10, laser light was irradiated along the butting surface of the first metal member and the second metal member. Therefore, the first columnar crystal structure part is not formed in the cross section perpendicular to the diffusion layer. Furthermore, the average thickness of the diffusion layer is greater than 50 µm. As a result, in the metal joining material of the comparative example, the tensile strength ratio and the elongation ratio were inferior, and the dispersion of the resistance values of the comparative examples 1 to 3 was also large.

1: Metal bonding material 10: The first metal part 11, 13: Die 12: The first columnar crystal structure 14: The second columnar crystal structure 15: boundary surface 16: The first baseline 17a, 17b, 22a, 22b: outline line 18: The first area 20: The second metal part 21: Specific crystallization baseline 23: Specific crystal structure department 24: Double crystal reference line 25: Double crystal organization department 30: diffusion layer 50: Butt surface B1, B2: average interval size h: distance X: Joint direction Y: direction of joint surface

Fig. 1 is a perspective view showing the outline of the metal bonding material of the embodiment. Figure 2 is an image obtained by observing the cross section of the diffusion layer perpendicular to the metal bonding material according to the embodiment using the electron backscatter diffraction (EBSD) method. Fig. 3 is a schematic diagram showing each structure in the image of Fig. 2. Figure 4 is the line analysis result of the electron probe microanalysis (EPMA) of the image in Figure 2. Fig. 5 is a perspective view for explaining the irradiation position of laser light in the embodiment.

Domestic deposit information (please note in the order of deposit institution, date and number) without Foreign hosting information (please note in the order of hosting country, institution, date, and number) without

1: Metal bonding material

10: The first metal part

12: The first columnar crystal structure

14: The second columnar crystal structure

15: boundary surface

20: The second metal part

30: diffusion layer

X: Joint direction

Y: direction of joint surface

Claims (16)

A metal joining material is formed by joining a first metal part and a second metal part. The metal joining material is characterized in: The first metal component and the second metal component are joined via a diffusion layer; In the cross section perpendicular to the diffusion layer, among the first metal component and the second metal component, only the first metal component has a first columnar crystal structure portion, and the first columnar crystal structure portion is adjacent to the The diffusion layer includes a plurality of crystal grains extending in a direction away from the aforementioned diffusion layer. The metal joining material according to claim 1, wherein, in the cross section, among all the crystal grains in the first columnar crystal structure portion, the area occupied by a plurality of crystal grains having an aspect ratio of 0.50 or less The ratio is more than 50%. The metal joining material according to claim 1 or 2, wherein in the cross section, the average thickness of the first columnar crystal structure portion is 50 μm or more and 500 μm or less. A metal joining material is formed by joining a first metal part and a second metal part, wherein: The first metal member and the second metal member are joined via a diffusion layer, and the average thickness of the diffusion layer is 50 μm or less. The metal joining material according to any one of claims 1 to 4, wherein in the cross section, the first metal member has a second metal member on the opposite side of the diffusion layer side of the first columnar crystal structure part A columnar crystal structure portion, the second columnar crystal structure portion including a plurality of crystal grains extending in a direction away from the first columnar crystal structure portion. The metal joining material according to claim 5, wherein in the cross section, the first metal member has a boundary surface between the first columnar crystal structure portion and the second columnar crystal structure portion. The metal joining material according to claim 6, wherein, in the cross section, the distance is 400 μm away from the boundary surface, parallel to the boundary surface, and from the boundary surface to the opposite side to the second metal member side. In the first region divided by the first reference line and the two outline lines of the first metal component, the area ratio of the crystal grains having an aspect ratio of 0.35 or less is 50% or more. The metal joining material according to any one of claims 1 to 7, wherein the ratio of the thermal conductivity λ2 of the second metal component to the thermal conductivity λ1 of the first metal component at 25°C (λ2/λ1 ) Is 10 or more, The difference ΔT between the melting point T1 of the first metal member and the melting point T2 of the second metal member is 10° C. or more. The metal joining material according to any one of claims 1 to 8, wherein the first metal member is an aluminum-based material, and the second metal member is a copper-based material. The metal joining material according to any one of claims 1 to 8, wherein the first metal member is an iron-based material, and the second metal member is a copper-based material. The metal joining material according to any one of claims 1 to 8, wherein the first metal member and the second metal member are aluminum-based materials. The metal joining material according to any one of claims 1 to 8, wherein the first metal member and the second metal member are iron-based materials. The metal joining material according to any one of claims 1 to 8, wherein the first metal member and the second metal member are copper-based materials. The metal joining material according to any one of claims 1 to 8, wherein the first metal member is a copper alloy material for resistance materials, The second metal member is a copper-based material with a higher conductivity than the first metal member. The metal joining material according to claim 14, wherein the first metal component is a copper alloy material for resistance material, the copper alloy material for resistance material has an alloy composition, and the alloy composition contains 10.0% by mass or more and 14.0% by mass The following Mn, 1.0% by mass or more and 3.0% by mass or less Ni, the remainder is composed of Cu and unavoidable impurities. The metal joining material according to claim 14, wherein the first metal component is a copper alloy material for resistance material, the copper alloy material for resistance material has an alloy composition, and the alloy composition contains 6.0% by mass or more and 8.0% by mass The following Mn, 2.0% by mass or more and 4.0% by mass or less of Sn, the remainder is composed of Cu and unavoidable impurities.

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