Joining body

Abstract

To provide a joining body which has a small pushing deformation amount in ultrasonic joining without reducing a joining strength.SOLUTION: A joining body is made by ultrasonic-joining a copper member and a metal member. The electric conductivity of the copper member is 95%IACS or more. When t represents a thickness in a direction orthogonal to a joining interface of the copper member, at a position of 0.10×t from the joining interface toward the copper member, a Vickers hardness σ1 is 90 HV or less. When a ratio σ2 / σ1 of a Vickers hardness σ2 at a position of 0.25×t from the joining interface toward the copper member to the Vickers hardness σ1 at a position of 0.10×t from the joining interface toward the copper member is more than 1.00.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a bonded body in which a copper member and a metal member are ultrasonically bonded, and is suitable for use in, for example, home appliances, lead frames, power modules, semiconductor parts such as power devices, printed wiring boards, heat sinks, switch parts, motors, bus bars, connectors, and other electrical and electronic equipment parts. [Background technology]

[0002] Highly conductive copper materials are used in electronic and electrical equipment components, but in order to reduce Joule heat generated by the increasing currents used in electronic and electrical equipment in recent years, materials with particularly high conductivity, i.e., low electrical resistance, are required. When joining such a copper member made of copper material to another metal member, ultrasonic joining is sometimes used.

[0003] Ultrasonic bonding removes impurities such as oxide films from the surfaces of materials through friction caused by ultrasonic vibrations, forming clean, activated new surfaces on the bonding surfaces, and simultaneously applying pressure to create a solid-state bond. Ultrasonic bonding does not pass electric current through the materials, so it is effective for joining materials with low electrical resistance, such as copper. In addition, because the joining occurs in a solid state, there is no excessive thermal impact, so it is possible to join materials in which brittle phases would form if welding were used, and it is also possible to join dissimilar materials.

[0004] As mentioned above, ultrasonic bonding involves applying pressure and ultrasonic vibrations to the materials to be bonded, which causes the materials to dent due to plastic deformation. If the ultrasonic bonding energy is increased to achieve sufficient bond strength, the cross-sectional area of ​​the materials will decrease due to denting caused by plastic deformation, which can result in a decrease in bond strength or a defect in the shape of the material. On the other hand, if the ultrasonic bonding energy is controlled to be small in order to reduce the amount of indentation deformation due to plastic deformation, the bonding strength may be insufficient. Here, Patent Document 1 discloses that the thickness of the connecting portion of the ultrasonic bonding is made thicker than the thickness of the base material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-150450 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the ultrasonic bonding energy is high and the amount of deformation of the bonded members is large, the cross-sectional area of ​​the members is reduced, which may result in a decrease in bond strength or a defective shape. Patent Document 1 describes increasing the thickness of the plates at the bonded portion, but this type of processing has the disadvantage of increasing manufacturing costs. On the other hand, if the ultrasonic bonding energy is controlled to be small in order to reduce the indentation deformation, the bonding strength may be insufficient. Therefore, a bonded body in which the indentation deformation is reduced without reducing the bonding strength is desired.

[0007] The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a bonded body in which the amount of indentation deformation during ultrasonic bonding is reduced without reducing the bonding strength. [Means for solving the problem]

[0008] In order to solve the above problems, the inventors conducted extensive research and discovered that by reducing the hardness of the copper member near the interface, and making it even lower than the hardness of the base material, the joining interface can be locally deformed, thereby ensuring joining strength and reducing the amount of indentation deformation during ultrasonic joining.

[0009] The present invention has been made based on the above-mentioned findings, and a bonded body of a first aspect of the present invention is a bonded body in which a copper member and a metal member are ultrasonically bonded, wherein the electrical conductivity of the copper member is 95% IACS or more, and wherein, relative to a thickness t in a direction perpendicular to the bonded interface of the copper member, the Vickers hardness σ1 at a position 0.10×t from the bonded interface toward the copper member is 90 HV or less, and the ratio σ2 / σ1 of the Vickers hardness σ2 at a position 0.25×t from the bonded interface toward the copper member to the Vickers hardness σ1 at a position 0.10×t from the bonded interface toward the copper member exceeds 1.00.

[0010] The bonded body of aspect 1 of the present invention is a bonded body obtained by ultrasonically bonding a copper member and a metal member, each having a conductivity of 95% IACS or more, and therefore has excellent conductivity and is particularly suitable as a component for electrical and electronic devices. Furthermore, with respect to the thickness t in the direction perpendicular to the bonding interface of the copper member, the Vickers hardness σ1 at a position 0.10×t from the bonding interface toward the copper member is 90 HV or less, and the ratio σ2 / σ1 of the Vickers hardness σ2 at a position 0.25×t from the bonding interface toward the copper member to the Vickers hardness σ1 at a position 0.10×t from the bonding interface toward the copper member exceeds 1.00.Therefore, the hardness near the interface of the copper member is low, and by locally deforming only the bonding interface during ultrasonic bonding, ultrasonic bondability can be improved, and since the base material portion is sufficiently hard, indentation deformation of the copper member can be further reduced.

[0011] A joined body according to a second aspect of the present invention is the joined body according to the first aspect of the present invention, characterized in that the copper members have a semi-softening temperature of 250° C. or higher. According to the joined body of the second aspect of the present invention, the copper members have a semi-softening temperature of 250°C or higher, so that the copper members are less likely to recover and recrystallize due to softening even when heated during ultrasonic joining, and therefore it is possible to minimize indentation deformation of the copper members due to ultrasonic joining. Furthermore, the joined body can withstand use in high-temperature environments.

[0012] The joined body of aspect 3 of the present invention is characterized in that, in the joined body of aspect 1 or aspect 2 of the present invention, the copper member contains a Cu content of 99.9 mass% or more and one or more elements selected from Mg, P, Ag, Sn, Ca, and Ni in a range of 10 massppm to 500 massppm. According to the joined body of aspect 3 of the present invention, as described above, the copper members have a Cu content of 99.9 mass% or more and contain one or more elements selected from Mg, P, Ag, Sn, Ca, and Ni, thereby improving heat resistance and further minimizing indentation deformation of the copper members due to ultrasonic joining.

[0013] A joined body of a fourth aspect of the present invention is characterized in that, in the joined body of any one of the first to third aspects of the present invention, the copper members have a high-temperature Vickers hardness Hv(300) at 300°C of 50 HV or more. According to the joined body of aspect 4 of the present invention, the high-temperature Vickers hardness Hv(300) of the copper members at 300°C is 50 HV or more, so that the deformation resistance is high even when the material is heated by the heat generated during ultrasonic joining, making it possible to further reduce the indentation deformation of the copper members due to ultrasonic joining.

[0014] A joined body of a fifth aspect of the present invention is the joined body of any one of the first to fourth aspects of the present invention, characterized in that the copper members have a high-temperature Vickers hardness Hv(400) at 400°C of 40 HV or more. According to the joined body of aspect 5 of the present invention, the high-temperature Vickers hardness Hv(400) of the copper members at 400°C is 40HV or more, so that the deformation resistance is high even when the material is heated by the heat generated during ultrasonic joining, making it possible to further reduce the indentation deformation of the copper members due to ultrasonic joining.

[0015] The joined body of aspect 6 of the present invention is characterized in that, in any one of aspects 1 to 5 of the present invention, the ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) of the copper members at 300°C to the high-temperature Vickers hardness Hv(400) of the copper members at 400°C is 2.0 or less. According to the joined body of aspect 6 of the present invention, the ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) at 300°C to the high-temperature Vickers hardness Hv(400) at 400°C of the copper members is 2.0 or less, so that sudden indentation deformation during ultrasonic joining can be prevented and a stable interface can be formed. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a bonded body in which the amount of indentation deformation during ultrasonic bonding is reduced without reducing the bonding strength. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic explanatory diagram of a bonded body according to an embodiment of the present invention; [Figure 2] FIG. 2 is a flow diagram of a method for manufacturing a bonded body according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] A bonded body according to one embodiment of the present invention will be described below. The bonded body of this embodiment is used for, for example, home appliances, semiconductor parts such as lead frames, power modules and power devices, printed wiring boards, heat sinks, switch parts, motors, bus bars, connectors and other electric and electronic equipment parts.

[0019] As shown in FIG. 1, the bonded body 10 of this embodiment is formed by ultrasonically bonding a metal member 11 and a copper member 12 together. There are no particular limitations on the metal member 11, and it may be made of any of various metals. In this embodiment, specific examples of the metal material constituting the metal member 11 include copper, nickel, stainless steel, and the like.

[0020] The copper member 12 has a conductivity of 95% IACS or more and is therefore excellent in conductivity. 1, the copper member 12 is configured such that the ratio σ2 / σ1 of the Vickers hardness σ2 at a position B 0.25×t away from the bonding interface S toward the copper member 12 and the Vickers hardness σ1 at a position A 0.10×t away from the bonding interface S toward the copper member 12 exceeds 1.00, relative to the thickness t in the direction perpendicular to the bonding interface S of the copper member 12. In other words, the copper member 12 is configured such that the hardness in the vicinity of the bonding interface S (position A 0.10×t away from the bonding interface S toward the copper member 12) is lower than the hardness of the base material (position B 0.25×t away from the bonding interface S toward the copper member 12). Further, the Vickers hardness σ1 at a position A 0.10×t away from the joining interface S toward the copper member 12 is set to 90 HV or less.

[0021] In the joined body 10 of this embodiment, the copper member 12 preferably has a semi-softening temperature of 250° C. or higher. Furthermore, in the joined body 10 of this embodiment, it is preferable that the copper member 12 has a Cu content of 99.9 mass% or more and contains one or more elements selected from Mg, P, Ag, Sn, Ca, and Ni in a range of 10 massppm to 500 massppm.

[0022] In the joined body 10 of this embodiment, the high-temperature Vickers hardness Hv(300) of the copper member 12 at 300° C. is preferably 50 HV or more. Furthermore, in the joined body 10 of this embodiment, it is preferable that the high-temperature Vickers hardness Hv(400) of the copper member 12 at 400° C. is 40 HV or more. Furthermore, in the joined body 10 of this embodiment, it is preferable that the ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) of the copper member 12 at 300°C to the high-temperature Vickers hardness Hv(400) of the copper member 12 at 400°C is 2.0 or less.

[0023] The reasons for specifying the electrical conductivity, Vickers hardness ratio σ2 / σ1, half-softening temperature, component composition, and high-temperature Vickers hardness of the copper member 12 in the joined body 10 of this embodiment as described above will be explained below.

[0024] (conductivity) The copper member 12 in the joined body 10 of this embodiment has an electrical conductivity of 95% IACS or more. By making the copper member 12 have an electrical conductivity of 95% IACS or more, heat generation during electrical conduction can be suppressed, and the copper member 12 can be favorably used as electrical and electronic equipment components such as home appliances, lead frames, power modules, semiconductor components for power devices, printed wiring boards, heat sinks, switch components, motors, bus bars, and connectors. The conductivity of the copper member 12 is preferably 97% IACS or more, more preferably 98% IACS or more, and even more preferably 99% IACS or more.

[0025] (Vickers hardness σ1, σ2) The Vickers hardness σ1 at position A, 0.10×t away from the bonding interface S toward the copper member 12, is set to 90 HV or less, where σ1 is the thickness of the copper member 12 in the direction perpendicular to the bonding interface S. Because the hardness of the copper member 12 near the interface is low, the ultrasonic bondability can be improved by deforming the bonding interface. Here, ultrasonic bondability includes bonding strength and indentation deformation. The Vickers hardness σ1 is preferably 85 HV or less, and more preferably 80 HV or less. There is no limit to the Vickers hardness σ2 at position B, 0.25×t away from the joining interface S toward the copper member 12, but it is preferably 50 HV or higher. If the Vickers hardness σ2 is low, the amount of indentation deformation increases. If the material softens due to heat generated during joining, the Vickers hardness σ2 decreases and differs from the hardness of the original material.

[0026] (Vickers hardness ratio: σ2 / σ1) In the bonded body 10 of this embodiment, the ratio σ2 / σ1 of the Vickers hardness σ2 at a position B 0.25×t away from the bonded interface S toward the copper member 12 and the Vickers hardness σ1 at a position A 0.10×t away from the bonded interface S toward the copper member 12, relative to the thickness t in the direction perpendicular to the bonded interface S of the copper member 12, exceeds 1.00. As a result, the hardness of the copper member 12 in the vicinity of the bonding interface S (position A, 0.10×t from the bonding interface S toward the copper member 12) is lower than the hardness of the base material (position B, 0.25×t from the bonding interface S toward the copper member 12), and the vicinity of the bonding interface S of the copper member 12 is sufficiently deformed during ultrasonic bonding, thereby improving ultrasonic bondability. On the other hand, the base material portion of the copper member 12 is sufficiently hard and does not deform easily, so a bonded body 10 can be obtained in which the amount of indentation deformation of the entire copper member 12 is smaller. The Vickers hardness ratio σ2 / σ1 is preferably greater than 1.01, more preferably greater than 1.02, and even more preferably greater than 1.03.

[0027] (semi-softening temperature) In the joined body 10 of this embodiment, if the semi-softening temperature of the copper member 12 is high, the copper material is less likely to recover and soften due to recrystallization even when heated during ultrasonic joining, making it possible to further reduce the indentation deformation of the copper material due to ultrasonic joining. Therefore, in this embodiment, it is preferable that the semi-softening temperature after one hour of heat treatment is set to be equal to or higher than 250° C. In this embodiment, the semi-softening temperature was evaluated by measuring the Vickers hardness. The semi-softening temperature of the copper member 12 is more preferably 275°C or higher, even more preferably 300°C or higher, and even more preferably 325°C or higher.

[0028] (Mg, P, Ag, Sn, Ca, Ni) Mg, P, Ag, Sn, Ca, and Ni are elements that have the effect of improving heat resistance by forming solid solutions or precipitates in the copper matrix. Therefore, by including one or more elements selected from Mg, P, Ag, Sn, Ca, and Ni in the copper member 12 in a total amount ranging from 10 mass ppm to 500 mass ppm, the heat resistance of the copper member 12 can be improved without significantly reducing the electrical conductivity of the copper member 12, and it is possible to further reduce indentation deformation of the copper member due to ultrasonic bonding. In order to further improve the heat resistance of the copper member 12, the total content of one or more elements selected from Mg, P, Ag, Sn, Ca, and Ni is preferably 20 massppm or more, and more preferably 30 massppm or more. In order to further suppress a decrease in the electrical conductivity of the copper member 12, the total content of one or more elements selected from Mg, P, Ag, Sn, Ca, and Ni is preferably 400 massppm or less, and more preferably 300 massppm or less.

[0029] (High temperature Vickers hardness) In the joined body 10 of this embodiment, if the copper member 12 has a high high-temperature Vickers hardness, the deformation resistance is high even when the material is heated by the heat generated during ultrasonic joining, making it possible to further reduce the indentation deformation of the copper member 12 due to ultrasonic joining. Therefore, in this embodiment, it is preferable that the high-temperature Vickers hardness Hv(300) of the copper member 12 at 300° C. is 50 HV or more. The high temperature Vickers hardness Hv(300) of the copper member 12 at 300° C. is more preferably 55 HV or more, and even more preferably 60 HV or more.

[0030] Furthermore, in this embodiment, it is preferable that the high-temperature Vickers hardness Hv(400) of the copper member 12 at 400° C. is 40 HV or more. The high temperature Vickers hardness Hv(400) of the copper member 12 at 400° C. is more preferably 45 HV or more, and even more preferably 50 HV or more.

[0031] Furthermore, in the bonded body 10 of this embodiment, if the ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) at 300°C to the high-temperature Vickers hardness Hv(400) at 400°C of the copper member 12 is small, sudden plastic deformation during ultrasonic bonding can be prevented, and a stable interface can be formed. Therefore, in this embodiment, it is preferable that the ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) of the copper member 12 at 300°C to the high-temperature Vickers hardness Hv(400) at 400°C is 2.0 or less. The ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) at 300°C to the high-temperature Vickers hardness Hv(400) at 400°C of the copper member 12 is more preferably 1.9 or less, and even more preferably 1.8 or less.

[0032] Next, an example of a method for producing the bonded body 10 according to this embodiment will be described with reference to the flow chart shown in FIG. The method for manufacturing the bonded body 10 in this embodiment includes a metal member preparing step S01, a copper member preparing step S02, and an ultrasonic bonding step S03.

[0033] <Metal component preparation process S01> First, prepare the metal member 11 that constitutes the bonded structure 10. As described above, the metal member 11 may be made of any of various metals, and there are no particular limitations on its shape. In this embodiment, a commercially available metal plate is used as the metal member 11. Here, the thickness of the metal plate that becomes the metal member 11 is preferably within the range of 0.1 mm to 5 mm.

[0034] <Copper material preparation process S02> Also, a copper member 12 is prepared to form the bonded body 10. There are no particular limitations on the shape of the copper member 12. In this embodiment, a copper plate is used as the copper member 12. Here, the thickness of the copper plate that becomes the copper member 12 is preferably within the range of 0.1 mm to 5 mm. In this embodiment, the copper member preparation step S02 includes a melting and casting step S21, a homogenization step S22, a hot rolling step S23, a rough rolling step S24, an intermediate heat treatment step S25, and a cold rolling step S26. Each step will be described below.

[0035] (Melting and casting process S21) First, the copper raw material is melted, and the above-mentioned elements are added to the resulting molten copper to adjust the composition, producing a molten copper alloy. The various elements can be added as simple elements or master alloys. Raw materials containing the above-mentioned elements may also be melted together with the copper raw material. Recycled or scrap materials of the alloy may also be used. Here, the copper raw material is preferably so-called 4NCu, which has a purity of 99.99 mass% or more, or so-called 5NCu, which has a purity of 99.999 mass% or more. During melting, in order to reduce the hydrogen concentration, it is preferable to perform atmospheric melting in an inert gas atmosphere (e.g., Ar gas) with a low HO vapor pressure, and to minimize the holding time during melting. The molten copper alloy with the adjusted composition is then poured into a mold to produce an ingot. Note that, when considering mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0036] (Homogenization step S22) Next, the resulting ingot is subjected to a heat treatment for homogenization, and the ingot is preferably held at a temperature of 600°C to 1050°C for at least one hour. Although there is no upper limit to the holding time in the homogenization step S22, it is preferably 24 hours or less in consideration of costs and production efficiency. There is also no particular limit to the cooling rate in the homogenization step S22, and air cooling or water cooling may be used.

[0037] (Hot rolling process S23) Next, hot rolling is performed. This hot rolling step may also serve as the homogenization step S22. After holding at 600°C or higher and 1050°C or lower for at least one hour, hot working is performed at 600°C or higher and 1050°C or lower, and then water cooling is performed. Then, facing is performed to remove the oxide film formed on the surface during hot rolling.

[0038] (Rough rolling process S24) Rough rolling is performed to roll the material into a predetermined shape. The temperature conditions in this rough rolling step S24 are not particularly limited, but in order to suppress recrystallization or improve dimensional accuracy, it is preferable to perform cold or warm rolling at a temperature in the range of −200° C. to 200° C., and room temperature is particularly preferable. The rolling reduction is preferably 20% or more, and more preferably 30% or more.

[0039] (Intermediate heat treatment process S25) After the rough rolling step S24, a heat treatment is performed to soften the material. The heat treatment method is not particularly limited, but it is preferably performed in a non-oxidizing or reducing atmosphere. The heat treatment temperature is preferably in the range of 500°C to 900°C. The intermediate heat treatment step S25 and the cold rolling step S26 described below may be repeated.

[0040] (Cold rolling process S26) The copper material after the intermediate heat treatment step S25 is cold-rolled to be worked into a predetermined shape. The temperature conditions in this cold-rolling step S26 are not particularly limited, but in order to suppress recrystallization or softening during working, it is preferable to set the temperature within the range of -200°C to 200°C, which is cold or warm working, and room temperature is particularly preferable. The rolling reduction ratio at this time is preferably adjusted within the range of 10% to 80% depending on the material so that the semi-softening temperature is 250° C. or higher.

[0041] A copper plate that becomes the copper member 12 is manufactured by the above-mentioned melting and casting step S21, homogenizing step S22, hot rolling step S23, rough rolling step S24, intermediate heat treatment step S25, and cold rolling step S26.

[0042] <Ultrasonic bonding process S03> Then, the copper member 12 and the metal member 11 obtained as described above are ultrasonically bonded to form the bonded body 10 of this embodiment. The ultrasonic bonding conditions are as follows: the height of the knurl is 0.6×t or less, the vibration amplitude is in the range of 15 μm to 24 μm, the semi-softening temperature is Th (°C), the bonding energy is E (J), and the cross-sectional area of ​​the bonded portion is A (mm 2 ) and the joint cross-sectional area A is calculated by multiplying the thickness t by the width W (mm), where W is the smaller of the plate width or three times the length of the horn size b (mm), (0.0033×Th+4.7)×(A×b 0.8 )≦E≦(0.016×Th+19.2)×(A×b 0.8 ) The joining conditions must satisfy the following. Increasing the joining energy also increases the heat generated during ultrasonic joining, leading to softening of the material and affecting σ1, σ2, and σ2 / σ1. If the joining energy is too small, σ1 will be high. If the joining energy is too large, σ2 / σ1 will be low. The bonding energy is (0.0033×Th+4.7)×(A×b 0.8 If the bonding energy is smaller than (0.016×Th+19.2)×(A×b), the bonding strength may be insufficient. 0.8 ), the amount of deformation due to indentation becomes excessive, and the cross-sectional area of ​​the copper member 12 decreases, which may cause the joint strength to exceed its peak and result in a decrease in the joint strength or a defective shape.

[0043] The bonded body 10 of this embodiment is manufactured through the above-described steps.

[0044] According to the bonded body 10 of this embodiment configured as described above, the bonded body 10 is formed by ultrasonically bonding the copper member 12 and the metal member 11, each having a conductivity of 95% IACS or more, and therefore has excellent conductivity and is particularly suitable as a component for electrical and electronic devices. Furthermore, with respect to the thickness t of the copper member 12 in the direction perpendicular to the bonding interface S, the Vickers hardness σ1 at a position 0.10×t from the bonding interface S toward the copper member 12 is 90 HV or less, and the ratio σ2 / σ1 of the Vickers hardness σ2 at a position 0.25×t from the bonding interface toward the copper member to the Vickers hardness σ1 at a position 0.10×t from the bonding interface toward the copper member exceeds 1.00. Therefore, the hardness of the copper member 12 near the bonding interface S is lower than that of the base material, and ultrasonic bondability can be improved by locally deforming only the bonding interface S during ultrasonic bonding. Furthermore, the base material portion is sufficiently hard, making it possible to further reduce indentation deformation of the copper member 12. Therefore, a bonded body 10 can be provided in which the amount of indentation deformation during ultrasonic bonding is reduced without reducing bonding strength.

[0045] In this embodiment, when the semi-softening temperature of the copper member 12 is 250°C or higher, the copper member 12 is less likely to undergo softening due to recovery and recrystallization even when heated in the ultrasonic bonding step S03, which makes it possible to further reduce the indentation deformation of the copper member 12 due to ultrasonic bonding.In addition, the copper member 12 can withstand use in high-temperature environments.

[0046] In this embodiment, when the copper member 12 has a Cu content of 99.9 mass% or more and contains one or more selected from Mg, P, Ag, Sn, Ca, and Ni in a range of 10 massppm to 500 massppm, the heat resistance of the copper member 12 can be improved, and the indentation deformation of the copper member 12 can be further reduced.

[0047] In this embodiment, when the high-temperature Vickers hardness Hv(300) of the copper member 12 at 300°C is 50HV or more, the deformation resistance is high even when the material is heated by the heat generated in the ultrasonic bonding process S03, making it possible to further reduce the indentation deformation of the copper member 12 due to ultrasonic bonding.

[0048] In this embodiment, when the high-temperature Vickers hardness Hv(400) of the copper member 12 at 400°C is 40HV or more, the deformation resistance is high even when the material is heated by the heat generated in the ultrasonic bonding process S03, making it possible to further reduce the indentation deformation of the copper member 12 due to ultrasonic bonding.

[0049] In this embodiment, when the ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) of the copper member 12 at 300°C to the high-temperature Vickers hardness Hv(400) of the copper member 12 at 400°C is 2.0 or less, sudden plastic deformation during ultrasonic bonding can be prevented and a stable interface can be formed.

[0050] Although the bonded body according to the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical concept of the invention. In the present embodiment, the metal member is a metal plate and the copper member is a copper plate, but the present invention is not limited to this, and the metal member and the copper member may be wire rods. Furthermore, in the above-described embodiment, an example of a method for manufacturing a copper member is described, but the method for manufacturing a copper member is not limited to that described in the embodiment, and the copper member may be manufactured by appropriately selecting an existing manufacturing method. Furthermore, the means for obtaining the bonded body is not limited to a particular method, but for example, it is possible to obtain the bonded body by controlling the ultrasonic bonding conditions as described above. [Example]

[0051] The results of confirmation experiments conducted to confirm the effects of the present invention will be described below.

[0052] A copper raw material with a purity of 99.9% by mass or higher was prepared and placed in an alumina crucible. It was then melted in an induction furnace under an Ar gas atmosphere. Various elements were added to the resulting molten copper. These elements were added using a Cu master alloy. This resulted in a molten copper alloy with the composition shown in Table 1, which was then poured into a carbon mold to produce an ingot. The size of the ingot was approximately 25 mm thick, 70 mm wide, and 100 mm long.

[0053] The resulting ingot was heated to 900°C for 1 hour in an Ar gas atmosphere for homogenization, and then hot-rolled to a thickness of 10 mm. After hot-rolling, it was water-cooled. After hot-rolling, the ingot was chamfered to remove the oxide film formed on the surface. Next, rough rolling, heat treatment, and cold rolling were carried out under the conditions shown in Table 1 to produce copper members A to O with a plate thickness of 0.8 mm.

[0054] Next, as shown in Table 2, a metal member (thickness 0.8 mm) and the above-mentioned copper members A to O (thickness 0.8 mm) were ultrasonically bonded under the conditions shown in Table 2 to prepare bonded bodies. The sample dimensions were 20 mm wide x 40 mm long, with two samples joined together with an overlap of 20 mm. Ultrasonic joining was performed using a power supply (2000Xdt 20 kHz, 4000 W) manufactured by Emerson Japan, an actuator (20DP-Xaed-100), and a horn with a tip that was 6 mm square and had 5 x 5 projections arranged at 1 mm pitch.

[0055] The bonded bodies of the invention examples and comparative examples obtained as described above were evaluated as follows.

[0056] (Composition of copper components) Measurement samples were taken from the resulting ingots, and component analysis was carried out using a glow discharge mass spectrometer (GD-MS).

[0057] (Conductivity of copper materials) The metal members were removed from the bonded body, and only the copper members were sampled. The conductivity was measured at a frequency of 500 kHz using an eddy current conductivity meter (AutoSigma 3000, manufactured by GE Inspection Technologies). The evaluation results are shown in Table 3. The evaluation samples may be sampled from the bonded body or from the copper members before bonding.

[0058] (semi-softening temperature of copper material) Test pieces were taken from the joined body at a position at least 5 x t away from the joint edge, where t is the thickness of the copper members. In accordance with JCBA T325:2013 of the Japan Copper and Brass Association, an isochronal softening curve was obtained using Vickers hardness after one hour of heat treatment to evaluate the semi-softening temperature of the copper members. The test load was 0.98 N. The evaluation results are shown in Table 3. In addition to being taken from the joined body, test pieces may also be taken from the copper members before joining.

[0059] (High temperature Vickers hardness of copper components) Test pieces were taken from the bonded structure at a position at least 5 × t away from the bonded edge, where t is the thickness of the copper members, and measured according to the high-temperature Vickers hardness test method specified in JIS-Z2252. The temperature was raised at a rate of 20°C per minute, held for 5 minutes, and then tested at test temperatures of 300°C and 400°C with a test load of 0.98N. The evaluation results are shown in Table 3. Note that test pieces can be taken from the bonded structure or from the copper members before bonding.

[0060] (Hardness of the copper material near the joint interface and the base material) The hardness σ1 of the copper component at a position 0.10×t away from the joining interface toward the copper component, and the hardness σ2 at a position 0.25×t away from the joining interface toward the copper component, relative to the thickness t of the copper component, were measured, and the ratio σ2 / σ1 was calculated. The hardness was measured in accordance with the micro Vickers hardness test method specified in JIS-Z2244. Vickers hardness was measured at a test load of 0.20 N on a cross section of the bonded material perpendicular to the ultrasonic vibration direction. The evaluation results are shown in Table 3.

[0061] (Joining strength) The joint strength was measured by a tensile shear test based on JIS-Z3136. A splice plate of the same thickness as the test piece was attached to the joint, and the test was carried out with a clamp distance of 40 mm and a tensile speed of 1 mm / min. The maximum load obtained was taken as the joint strength. The evaluation results are shown in Table 3.

[0062] (Indentation deformation amount) The amount of indentation deformation is the distance the horn of the ultrasonic welding machine displaces from the time it comes into contact with the material and ultrasonic vibration begins until oscillation stops, and corresponds to the amount of depression caused by plastic deformation of the material. This amount of displacement is the weld collapse value displayed on the ultrasonic welding machine when welding is performed. The evaluation results are shown in Table 3.

[0063] [Table 1]

[0064] [Table 2]

[0065] [Table 3]

[0066] In Comparative Example 1, σ2 / σ1 was low at 0.98, the amount of indentation deformation was large, and the joint strength exceeded its peak, resulting in a joint strength lower than that of the invention example. In Comparative Example 2, σ1 was as high as 101 HV, and although the indentation deformation amount was small, the bonding strength was low.

[0067] In contrast, in Examples 1 to 13 of the present invention, it was confirmed that the copper members had high electrical conductivity, sufficient bonding strength, and small amounts of indentation deformation during ultrasonic bonding. From the above, it was confirmed that the present invention can provide a bonded body in which the copper member has high electrical conductivity and the amount of indentation deformation during ultrasonic bonding is small without reducing the bonding strength.

Claims

1. A bonded body in which a copper member and a metal member are ultrasonically bonded, The conductivity of the copper member is 95% IACS or more, With respect to a thickness t in a direction perpendicular to the bonding interface of the copper member, the Vickers hardness σ1 at a position 0.10 × t from the bonding interface to the copper member side is 90 HV or less, A bonded body characterized in that the ratio σ2 / σ1 of the Vickers hardness σ2 at a position 0.25 × t from the bonding interface to the copper member side and the Vickers hardness σ1 at a position 0.10 × t from the bonding interface to the copper member side exceeds 1.

00.

2. 2. The joined body according to claim 1, wherein the copper member has a semi-softening temperature of 250° C. or higher.

3. The joined body according to claim 1 or 2, characterized in that the copper member has a Cu content of 99.9 mass% or more and contains one or more elements selected from Mg, P, Ag, Sn, Ca, and Ni in a range of 10 mass ppm to 500 mass ppm.

4. 3. The joined body according to claim 1, wherein the copper members have a high-temperature Vickers hardness Hv(300) at 300° C. of 50 HV or more.

5. 3. The joined body according to claim 1, wherein the copper members have a high-temperature Vickers hardness Hv(400) at 400° C. of 40 HV or more.

6. 3. The joined body according to claim 1, wherein the ratio Hv(300) / Hv(400) of the high-temperature Vickers hardness Hv(300) of the copper member at 300°C to the high-temperature Vickers hardness Hv(400) of the copper member at 400°C is 2.0 or less.

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