Shunt resistor and method for manufacturing the same

Abstract

This invention provides a shunt resistor that is advantageous for weight reduction and can obtain a stable electrical resistance value. [Solution] The device comprises a shunt resistor 30, a first conductive member 10 joined to one end of the shunt resistor 30, and a second conductive member 20 joined to the other end of the shunt resistor 30, wherein the second conductive member 20 is made of a metal with a lower specific gravity than the first conductive member 10. This structure is advantageous in terms of weight reduction compared to conventional products. In addition, compared to conventional products, there are fewer joining processes, resulting in fewer joining interfaces and the advantage of more stable electrical resistance. Furthermore, fewer joining processes are advantageous in terms of cost and management during manufacturing. Moreover, the amount of expensive copper used is less compared to conventional products, which reduces costs.

Description

Technical Field

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[0001] The present invention relates to a shunt resistor and a method for manufacturing the same.

Background Art

[0002] A copper alloy for electric resistance (JIS CM44, Cu - 10 to 13 wt% Mn - 1 to 4 wt% Ni) has a small temperature dependence of its electric resistance value and is used as a shunt resistor for managing the electrical characteristics of in - vehicle lithium - ion batteries. Such a shunt resistor is generally composed of a joined body in which pure copper is joined as a conductor to one end and the other end of the above - mentioned copper alloy for electric resistance.

[0003] In the above - mentioned conventional shunt resistor, electron beam welding is used for their joining in order to thin the interfacial reaction layer between the copper alloy for electric resistance and the conductor (pure copper) and suppress the increase in the electric resistance value at the interface.

[0004] On the other hand, copper wiring has been used in electric vehicles using in - vehicle lithium - ion batteries. However, since copper is expensive and has a large specific gravity, the application of low - cost and lightweight aluminum wiring is desired.

[0005] However, it is difficult to join the copper alloy for electric resistance to aluminum, and in fact, the application of aluminum in the wiring around the shunt resistor has not progressed.

[0006] The applicant of the present application is aware of the following Patent Document 1 as a prior art document regarding a shunt resistor to which aluminum wiring can be applied.

Prior Art Document

Patent Document

[0007]

Patent Document 1

[0008] The above-mentioned Patent Document 1 discloses a method for manufacturing a busbar device and contains the following description.

[0063] In the following description, we will first describe a first exemplary embodiment as shown in Figures 1A-1F, 2A-2F, and 3. Figures 1A-1F each show various method steps of the manufacturing method according to the present invention for producing the final composite material strip 1 shown in Figure 1F. Figures 2A-2F show top views of the individual method steps according to Figures 1A-1F. However, Figure 3 shows the manufacturing method in the form of a flow chart.

[0064] In the first method step S1, the bistrip 2 is first assembled from an aluminum strip 3 and a copper strip 4 by, for example, laser-induced roll plating along a longitudinal seam 5.

[0065] In the second step S2, another bistrip 6 is assembled from a manganin® strip 7 and a copper strip 8, for example, by electron beam welding.

[0066] In the third step S3, the two bi-strips 2 and 6 are joined together by electron beam welding. Here, the copper strip 4 is welded to the manganin® strip 7, which can be easily done by electron beam welding.

[0067] In another step S4, the resulting composite material strip 9 is joined to another aluminum strip 10 by electron beam welding.

[0009] In other words, Patent Document 1 describes a method for manufacturing a busbar having a shunt resistor, which involves joining a copper conductive material (8) to one end of a resistive material, manganin (registered trademark) (7), joining a copper conductive material (4) to the other end, and joining an aluminum conductive material (3) to the copper conductive material (4) (see Figures 1A and 1D). [Disclosure of the Invention] [Problems that the invention aims to solve]

[0010] However, in the technology described in Patent Document 1, a copper conductive material (4) is joined to the other end of the manganin (registered trademark) (7), and an aluminum conductive material (3) is joined to the copper conductive material (4). As a result, a large amount of copper is used, which is disadvantageous for weight reduction. The more joining steps there are, the more joining interfaces there are, which increases the risk of unstable electrical resistance. In addition, the large number of joining steps is disadvantageous in terms of cost and management during manufacturing. Furthermore, because copper conductive materials are joined to both ends of the manganin (registered trademark), a large amount of expensive copper is used, which increases the cost.

[0011] This invention was made with the following objectives in order to solve the above-mentioned problems. The present invention provides a shunt resistor that is advantageous for weight reduction and can obtain a stable electrical resistance value, as well as a method for manufacturing the same. [Means for solving the problem]

[0012] The shunt resistor described in claim 1 employs the following configuration to achieve the above objective. Shunt resistor and A first conductive member is joined to one end of the above-mentioned shunt resistor member, The shunt resistor member comprises a second conductive member joined to the other end of the shunt resistor member, The second conductive member is a metal with a lower specific gravity than the first conductive member.

[0013] The shunt resistor described in claim 2 adopts the following configuration in addition to the configuration described in claim 1. A compound layer with a thickness of 2 μm or less exists at the interface between the above-mentioned shunt resistor and the above-mentioned second conductive member. A layered solidified structure exists at the interface between the shunt resistance member and the first conductive member.

[0014] The shunt resistor according to claim 3 employs the following configuration in addition to the configuration according to claim 2. A plastic flow region exists in the vicinity of the compound layer of the second conductive member.

[0015] The shunt resistor according to claim 4 employs the following configuration in addition to the configuration according to any one of claims 1 to 3. It exists as a part of the bus bar.

[0016] The shunt resistor according to claim 5 employs the following configuration in addition to the configuration according to any one of claims 1 to 3. The first conductive member is copper, and the second conductive member is aluminum.

[0017] The shunt resistor according to claim 6 employs the following configuration in addition to the configuration according to claim 5. The cross-sectional area of the cross-section orthogonal to the current direction of the first conductive member and the second conductive member is 1.2 to 2 times that of the second conductive member with respect to the first conductive member.

[0018] The method for manufacturing a shunt resistor according to claim 7 employs the following configuration in order to achieve the above object. Prepare a shunt resistor member, a first conductive member, and a second conductive member. Use a metal having a specific gravity smaller than that of the first conductive member as the second conductive member. Perform a first joining step of joining the first conductive member to one end of the shunt resistor member by electron beam welding, and a second joining step of joining the second conductive member to the other end of the shunt resistor member by friction stir welding.

[0019] The method for manufacturing a shunt resistor according to claim 8 employs the following configuration in addition to the configuration according to claim 7. The first conductive member is copper, and the second conductive member is aluminum.

Advantages of the Invention

[0020] The shunt resistor according to claim 1 comprises a shunt resistor member, a first conductive member, and a second conductive member. The first conductive member is joined to one end of the shunt resistor member. The second conductive member is joined to the other end of the shunt resistor member. The second conductive member is a metal with a lower specific gravity than the first conductive member. Thus, the first conductive member, which has a relatively higher specific gravity, is joined to one end of the shunt resistor member, while the second conductive member, which has a relatively lower specific gravity, is directly joined to the other end of the shunt resistor member. This structure is advantageous in terms of weight reduction compared to conventional products. In addition, compared to conventional products, there are fewer joining processes, resulting in fewer joining interfaces and a more stable electrical resistance value. Furthermore, fewer joining processes are advantageous in terms of cost and management during manufacturing. Moreover, the amount of expensive copper used is less compared to conventional products, which reduces costs.

[0021] The shunt resistor according to claim 2 has a compound layer with a thickness of 2 μm or less at the interface between the shunt resistor member and the second conductive member. This is a junction interface in which the measured electrical resistance value is stable, and exhibits excellent characteristics as a shunt resistor. Furthermore, a layered solidified structure exists at the interface between the shunt resistor member and the first conductive member. Such a layered solidified structure is a junction interface without elements that destabilize the measured electrical resistance value, and exhibits excellent characteristics as a shunt resistor.

[0022] The shunt resistor according to claim 3 has a plastic flow region near the compound layer of the second conductive member. Such a plastic flow region is a junction interface that does not contain elements that destabilize the measured electrical resistance value, and exhibits excellent characteristics as a shunt resistor.

[0023] The shunt resistor described in claim 4 exists as part of a busbar. Since the second conductive member connected to the other end of the shunt resistor member has a relatively low specific gravity, the busbar itself can be significantly lightened.

[0024] The shunt resistor according to claim 5 is characterized in that the first conductive member is copper and the second conductive member is aluminum. Copper, which has a relatively high specific gravity, is joined to one end of the shunt resistor, while aluminum, which has a relatively low specific gravity, is directly joined to the other end of the shunt resistor. This structure is advantageous in terms of weight reduction compared to conventional products. In addition, compared to conventional products, there are fewer joining processes, resulting in fewer bonding interfaces and the advantage of more stable electrical resistance. Furthermore, fewer joining processes are advantageous in terms of cost and management during manufacturing. Moreover, the amount of expensive copper used is less compared to conventional products, which reduces costs.

[0025] The shunt resistor according to claim 6 has a cross-sectional area of ​​the second conductive member perpendicular to the current direction, where the cross-sectional area of ​​the second conductive member is 1.2 to 2 times that of the first conductive member. The electrical resistance of aluminum, which is used for the second conductive member, is relatively higher than that of copper, which is used for the first conductive member. Therefore, by making the cross-sectional area of ​​the second conductive member perpendicular to the current direction of the first conductive member and the second conductive member 1.2 to 2 times that of the first conductive member, the electrical resistance values ​​of the first conductive member at one end of the shunt resistor and the second conductive member at the other end can be made equal, allowing for more stable measurement of electrical resistance.

[0026] The method for manufacturing a shunt resistor according to claim 7 involves preparing a shunt resistor member, a first conductive member, and a second conductive member, and using a metal with a lower specific gravity than the first conductive member as the second conductive member. Then, a first joining step is performed in which the first conductive member is joined to one end of the shunt resistor member by electron beam welding, and a second joining step is performed in which the second conductive member is joined to the other end of the shunt resistor member by friction stir welding. In this way, the first conductive member, which has a relatively higher specific gravity, is joined to one end of the shunt resistor member, while the second conductive member, which has a relatively lower specific gravity, is directly joined to the other end of the shunt resistor member. With this structure, a shunt resistor that is lighter than those produced by conventional methods can be obtained. In addition, compared to conventional methods, there are fewer joining steps, resulting in fewer joining interfaces and a shunt resistor with a more stable electrical resistance value. Furthermore, the reduced number of joining steps is advantageous in terms of cost and management during manufacturing. Moreover, the amount of expensive copper used is less than in conventional methods, which reduces costs.

[0027] The method for manufacturing a shunt resistor according to claim 8 is characterized in that the first conductive member is copper and the second conductive member is aluminum. Copper, which has a relatively high specific gravity, is joined to one end of the shunt resistor, while aluminum, which has a relatively low specific gravity, is directly joined to the other end of the shunt resistor. This structure is advantageous in terms of weight reduction compared to conventional methods. In addition, compared to conventional methods, there are fewer joining processes, resulting in fewer bonding interfaces and a more stable electrical resistance value. Furthermore, fewer joining processes are advantageous in terms of cost and management during manufacturing. Moreover, the amount of expensive copper used is less compared to conventional methods, thus reducing costs. [Brief explanation of the drawing]

[0028] [Figure 1] This is a front view illustrating an embodiment of a shunt resistor to which the present invention is applied. [Figure 2] This figure illustrates an embodiment of a method for manufacturing a shunt resistor to which the present invention is applied, where (A) is a front view and (B) is a top view. [Figure 3] The above diagram illustrates the manufacturing method, with (A) being a front view and (B) being a top view. [Figure 4] This is an enlarged cross-sectional view illustrating the shunt resistor shown above. [Figure 5] This diagram illustrates a modified version of the above shunt resistor, with (A) being a front view of the first example and (B) being a top view of the second example. [Modes for carrying out the invention]

[0029] Next, embodiments for carrying out the present invention will be described.

[0030] Figure 1 is a front view illustrating one embodiment of a shunt resistor to which the present invention is applied. The following description shows an example in which the shunt resistor of the present invention exists as part of a busbar.

[0031] This shunt resistor comprises a shunt resistor member 30, a first conductive member 10, and a second conductive member 20. The first conductive member 10 is joined to one end of the shunt resistor member 30, and the second conductive member 20 is joined to the other end of the shunt resistor member 30.

[0032] As the above-mentioned shunt resistor member 30, for example, an electrical resistance copper alloy (JIS CM44, Cu-10~13wt%Mn-1~4wt%Ni: manganin; registered trademark) can be used. Such an electrical resistance copper alloy is stable over a long period of time and has an extremely small temperature dependence of its resistivity, making it suitable for use as a resistance material for shunt resistors inserted into circuits for measuring current values. In this invention, the above-mentioned shunt resistor member 30 is not limited to the above-mentioned manganin (registered trademark), and other copper alloys can also be applied. For example, copper-manganese resistance alloys such as R270 (Cu-10wt%Mn-4wt%Ni), MC1 (Cu-12wt%Mn-3wt%Ni), MC2 (Cu-7wt%Mn-2.3wt%Ni), and CM44 (Cu-12wt%Mn-2wt%Ni), as well as copper alloys such as CN30 (Cu-1.5wt% or less Mn-20~25wt%Ni), CN49 (Cu-0.5~2.5wt%Mn-42~48wt%Ni), and gelanine 30 (Cu-7wt%Mn-2.3wt%Sn).

[0033] In this embodiment, the second conductive member 20 is a metal with a lower specific gravity than the first conductive member 10. Specifically, copper can be used as the first conductive member 10, and aluminum can be used as the second conductive member 20.

[0034] In this configuration, copper, which has a relatively high specific gravity, is joined to one end of the shunt resistor 30, while aluminum, which has a relatively low specific gravity, is directly joined to the other end of the shunt resistor 30. This structure is advantageous in terms of weight reduction compared to conventional products. Furthermore, it has the advantage of having fewer bonding interfaces (fewer bonding processes) compared to conventional products, resulting in more stable electrical resistance. The reduced number of bonding processes is also advantageous in terms of cost and management during manufacturing. In addition, it uses less expensive copper compared to conventional products, thus lowering costs.

[0035] Figures 2 and 3 illustrate one embodiment of a method for manufacturing a shunt resistor to which the present invention is applied.

[0036] A shunt resistor 30, a first conductive member 10, and a second conductive member 20 are prepared. The shunt resistor 30, the first conductive member 10, and the second conductive member 20 are each plate-shaped. The shunt resistor 30 is a narrower strip than the first conductive member 10 and the second conductive member 20. A metal with a lower specific gravity than the first conductive member 10 is used for the second conductive member 20. As described above, copper can be used for the first conductive member 10, and aluminum can be used for the second conductive member 20.

[0037] Figure 2 illustrates the first joining process for joining the shunt resistance member 30 and the first conductive member 10, where (A) is a front view and (B) is a top view.

[0038] As shown in Figure 2, first, the first conductive member 10 is joined to one end of the shunt resistance member 30 by electron beam welding. That is, the shunt resistance member 30 and the first conductive member 10 are placed abutting against each other, and the electron beam 40 is irradiated onto the abutting joint between the shunt resistance member 30 and the first conductive member 10. 40A is the irradiation area (spot) of the electron beam 40, and the irradiation area 40A is moved along the boundary where the shunt resistance member 30 and the first conductive member 10 abutting against each other (arrow L in the figure). As a result, the abutting joint between the shunt resistance member 30 and the first conductive member 10 melts and then solidifies, joining the shunt resistance member 30 and the first conductive member 10 by welding.

[0039] Figure 3 illustrates the second joining process for joining the shunt resistance member 30 and the second conductive member 20, where (A) is a front view and (B) is a top view.

[0040] As shown in Figure 3, the second conductive member 20 is joined to the other end of the shunt resistance member 30 by friction stir welding. Specifically, the shunt resistance member 30 and the second conductive member 20 are placed abutting against each other, and a rotating tool 50, for example, formed in the shape of a cylinder, is inserted into the second conductive member 20 near the abutting joint between the shunt resistance member 30 and the second conductive member 20 while rotating, and moved along the boundary where the shunt resistance member 30 and the second conductive member 20 abut. At this time, the rotating tool 50 is pressed into the second conductive member 20 side and does not come into contact with the shunt resistance member 30. In this way, the shunt resistance member 30 and the second conductive member 20 are joined while plastic flow is generated in the second conductive member 20.

[0041] The rotary tool 50 can be formed from, for example, hardened tool steel. The rotary tool 50 is rotated around its central axis (arrow R in the figure) and its tip surface (bottom surface in the figure) is lowered so as to press down on the second conductive member 20 (arrow D in the figure), and in that state it is moved along the boundary where the shunt resistance member 30 and the second conductive member 20 meet (arrow F in the figure). This causes plastic flow in the second conductive member 20, and the plastically flowed second conductive member 20 comes into close contact with the shunt resistance member 30, joining the two together. In the illustrated example, the tip surface of the rotary tool 50 is flat.

[0042] The rotational speed of the rotary tool 50 can be set to approximately 1000 to 3000 rpm. The speed at which the rotary tool 50 moves along the abutment boundary can be set to approximately 100 to 1000 mm / min.

[0043] As described above, a first conductive member 10 is joined to one end of the shunt resistor member 30, and a second conductive member 20 is joined to the other end of the shunt resistor member 30. The joined body is then cut, for example, at the position indicated by arrow S, to obtain a strip-shaped busbar. For example, press cutting can be used as the cutting method. The strip-shaped busbar includes a shunt resistor in which the first conductive member 10 is joined to one end of the shunt resistor member 30 and the second conductive member 20 is joined to the other end of the shunt resistor member 30.

[0044] In this embodiment, a first joining step is performed in which the first conductive member is joined to one end of the shunt resistor by electron beam welding, and then a second joining step is performed in which the second conductive member is joined to the other end of the shunt resistor by friction stir welding. By manufacturing in this order, the defect rate due to problems such as the joint peeling off during the process can be reduced.

[0045] Figure 4 is an enlarged cross-sectional view illustrating the shunt resistor manufactured as described above.

[0046] A compound layer 60 with a thickness of 2 μm or less exists at the interface between the shunt resistor 30 and the second conductive member 20, and a plastic flow region 65 exists near the compound layer 60 of the second conductive member 20. The compound layer 60 and the plastic flow region 65 are formed by the friction stir welding described above. The plastic flow region 65 exhibits a recrystallized structure due to the processing heat during manufacturing. The compound layer 60 is mainly AL2Cu or AL4Cu9 or both, and may contain small amounts of manganese. Because it is such a thin interface layer, it exhibits a stable resistance value and is advantageous as a shunt resistor for current measurement.

[0047] Furthermore, a layered solidified structure 70 exists at the interface between the shunt resistance member 30 and the first conductive member 10. This layered solidified structure 70 is formed by the electron beam welding described above. Specifically, the solidified structure 70 is mainly composed of copper, with manganese and nickel mixed in.

[0048] The plastic flow region 65 described above may undergo further recrystallization by heat treatment after friction stir welding, and the present invention also encompasses embodiments exhibiting such a structure. Similarly, the layered solidification structure 70 described above may include a recrystallized structure resulting from heat treatment after electron beam welding, and the present invention also encompasses such embodiments.

[0049] Figure 5 illustrates a modified example of the shunt resistor described above.

[0050] In this example, the first conductive member 10 is made of copper, the second conductive member 20 is made of aluminum, and furthermore, the cross-sectional area of ​​the second conductive member 20 perpendicular to the current direction is such that the cross-sectional area of ​​the second conductive member 20 is 1.2 to 2 times that of the first conductive member 10.

[0051] Figure 5(A) is a front view of the first example. In this example, the thickness t2 of the second conductive member 20 is set to 1.6 times the thickness t1 of the first conductive member 10. The width dimensions of the first conductive member 10 and the second conductive member 20 are the same. By doing so, the cross-sectional area of ​​the second conductive member perpendicular to the current direction of the first conductive member 10 and the second conductive member 20 is 1.6 times that of the first conductive member 10.

[0052] Figure 5(B) is a plan view of the second example. In this example, the width W2 of the second conductive member 20 is set to 1.6 times the width W1 of the first conductive member 10. The thickness dimensions of the first conductive member 10 and the second conductive member 20 are the same. The width of the shunt resistor member 30 is the same as the width W2 of the second conductive member 20, and the two members of the same width are joined without offset, with the first conductive member 10 joined to the shunt resistor member 30 at an angle θ. By setting the angle θ to 38.68°, W2 becomes approximately 1.6 times W1 (from SINθ = W1 / W2). In this way, the cross-sectional area of ​​the second conductive member perpendicular to the current direction of the first conductive member 10 and the second conductive member 20 is 1.6 times that of the first conductive member 10.

[0053] According to the above embodiment, the following effects are achieved.

[0054] The above embodiment comprises a shunt resistor 30, a first conductive member 10, and a second conductive member 20. The first conductive member 10 is joined to one end of the shunt resistor 30. The second conductive member 20 is joined to the other end of the shunt resistor 30. The second conductive member 20 is made of a metal with a lower specific gravity than the first conductive member 10. Thus, the first conductive member 10, which has a relatively higher specific gravity, is joined to one end of the shunt resistor 30, while the second conductive member 20, which has a relatively lower specific gravity, is directly joined to the other end of the shunt resistor 30. This structure is advantageous in terms of weight reduction compared to conventional products. In addition, compared to conventional products, there are fewer joining processes, resulting in fewer joining interfaces and a more stable electrical resistance value. Furthermore, fewer joining processes are advantageous in terms of cost and management during manufacturing. Moreover, the amount of expensive copper used is less compared to conventional products, which reduces costs.

[0055] In the above embodiment, a compound layer 60 with a thickness of 2 μm or less exists at the interface between the shunt resistor 30 and the second conductive member 20. This is a junction interface in which the measured electrical resistance value is stable, and exhibits excellent characteristics as a shunt resistor. Furthermore, a layered solidified structure 70 exists at the interface between the shunt resistor 30 and the first conductive member 10. Such a layered solidified structure is a junction interface without elements that destabilize the measured electrical resistance value, and exhibits excellent characteristics as a shunt resistor.

[0056] In the above embodiment, a plastic flow region 65 exists near the compound layer 60 of the second conductive member 20. Such a plastic flow region 65 is a junction interface that does not contain any elements that destabilize the electrical resistance value being measured, and exhibits excellent properties as a shunt resistor.

[0057] The above embodiment exists as part of a busbar. Since the second conductive member 20 connected to the other end of the shunt resistor member 30 has a relatively low specific gravity, the busbar itself can be significantly lightened.

[0058] In the above embodiment, the first conductive member 10 is made of copper, and the second conductive member 20 is made of aluminum. Copper, which has a relatively high specific gravity, is joined to one end of the shunt resistor member 30, while aluminum, which has a relatively low specific gravity, is directly joined to the other end of the shunt resistor member 30. This structure is advantageous in terms of weight reduction compared to conventional products. In addition, compared to conventional products, there are fewer joining processes, resulting in fewer joining interfaces and the advantage of more stable electrical resistance. Furthermore, fewer joining processes are advantageous in terms of cost and management during manufacturing. Moreover, the amount of expensive copper used is less compared to conventional products, which reduces costs.

[0059] In the above embodiment, the cross-sectional area of ​​the second conductive member 20 perpendicular to the current direction of the first conductive member 10 is 1.2 to 2 times that of the first conductive member 10. The electrical resistance of aluminum, which is the second conductive member 20, is relatively higher than that of copper, which is the first conductive member 10. Therefore, by making the cross-sectional area of ​​the second conductive member 20 perpendicular to the current direction of the first conductive member 10 1.2 to 2 times that of the first conductive member 10, the electrical resistance values ​​of the first conductive member 10 at one end of the shunt resistor and the second conductive member 20 at the other end can be made equal, allowing for more stable measurement of electrical resistance.

[0060] As described above, according to this embodiment, the interface between the shunt resistor member 30 and the second conductive member 20 is a film-like compound layer 60 with a thickness of 2 μm or less, resulting in a stable electrical resistance interface. Therefore, stable current measurement is possible, and copper wiring can be replaced with aluminum wiring. For example, automotive lithium-ion batteries can be converted to aluminum wiring at low cost, promoting weight reduction. Furthermore, while welding the shunt resistor member 30 and aluminum with an electron beam results in a product with a large amount of compound and inferior electrical and mechanical properties, applying friction stir welding generates a thin, uniform film-like compound layer 60, making it possible to obtain a shunt resistor with a stable electrical resistance interface.

[0061] [Other variations] Although the above describes particularly preferred embodiments of the present invention, the present invention is not limited to the illustrated embodiments and can be implemented in various forms, and the present invention is intended to encompass various modifications.

[0062] For example, while the embodiments described above show examples where the shunt resistor of the present invention exists as part of a busbar, the invention is not limited to this, and shunt resistors that do not exist as part of a busbar are also included within the scope of the present invention.

[0063] Furthermore, in each of the above embodiments, a second joining step is performed in which the second conductive member is joined to the other end of the shunt resistance member by friction stir welding, after a first joining step in which the first conductive member is joined to one end of the shunt resistance member by electron beam welding. However, the invention is not limited to this, and the first joining step may be performed after the second joining step. [Explanation of Symbols]

[0064] 10: First conductive member 20: Second conductive member 30: Shunt Resistor 40: Electron beam 40A: Irradiation area 50: Rotary Tools 60: Compound layer 65: Plastic flow region 70: Coagulation tissue

Claims

1. Shunt resistor and A first conductive member is joined to one end of the above-mentioned shunt resistor member, The shunt resistor member comprises a second conductive member joined to the other end of the shunt resistor member, The second conductive member is a metal with a lower specific gravity than the first conductive member. A shunt resistor characterized by the following features.

2. A compound layer with a thickness of 2 μm or less exists at the interface between the above-mentioned shunt resistor and the above-mentioned second conductive member. A layered solidified structure exists at the interface between the shunt resistance member and the first conductive member. A shunt resistor according to claim 1.

3. A plastic flow region exists near the compound layer of the second conductive member described above. The shunt resistor according to claim 2.

4. It exists as part of the bus bar. A shunt resistor according to any one of claims 1 to 3.

5. The first conductive member is copper, and the second conductive member is aluminum. A shunt resistor according to any one of claims 1 to 3.

6. The cross-sectional area of ​​the second conductive member perpendicular to the current direction of the first conductive member and the second conductive member is 1.2 to 2 times that of the first conductive member. A shunt resistor according to claim 5.

7. Prepare a shunt resistor, a first conductive member, and a second conductive member. As the second conductive member, a metal with a lower specific gravity than the first conductive member is used. The process involves a first joining step of joining the first conductive member to one end of the shunt resistance member by electron beam welding, and a second joining step of joining the second conductive member to the other end of the shunt resistance member by friction stir welding. A method for manufacturing a shunt resistor characterized by the following:

8. The first conductive member is copper, and the second conductive member is aluminum. A method for manufacturing a shunt resistor according to claim 7.

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