Conductive connection member and method of manufacturing the same

Abstract

To provide a conductive connection member having an Erichsen value suitable for drawing or deep-drawing process, preferably 5 mm or more, or more preferably 7 mm or more.SOLUTION: A conductive connection member comprises a clad material in which a first metal layer composed of Al or Al alloy and a second metal layer composed of Fe or Fe alloy are laminated for cladding, or the first metal layer, the second metal layer, and a third metal layer composed of Al or Al alloy are laminated for cladding, with the second metal layer containing Cu of 0.50 mass% or less. Such a conductive connection member can be produced by a production method that includes laminating and cladding a first metal plate composed of Al or Al alloy and a second metal plate composed of Fe or Fe alloy in this order, or laminating and cladding the first metal plate, the second metal plate, and a third metal plate composed of Al or Al alloy in this order; and further applying a heat treatment to form a clad material, with the Cu content of the second metal plate controlled to 0.50 mass% or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a conductive connecting member used for electrical connection and a manufacturing method thereof, and more particularly to a conductive connecting member made of a clad material obtained by roll-bonding dissimilar metals and a manufacturing method thereof. [Background technology]

[0002] BACKGROUND ART Conductive connecting members used for electrical connection have been known in the past. Such conductive connecting members are disclosed, for example, in Patent Document 1 (Japanese Patent Laid-Open Publication No. 2000-30673) and Patent Document 2 (Japanese Patent Laid-Open Publication No. 2-117783).

[0003] Patent Document 1 discloses a battery can formed into a bottomed cylindrical shape by DI (Drawing and Ironing) a clad material made of a conductive material. This clad material is produced by a manufacturing method in which nickel plating is applied to the surface of SPCE (cold rolled steel sheet material) material to form a nickel-coated SPCE material, which is then heat treated, and then an aluminum material made of aluminum or an aluminum alloy is superimposed on the nickel-coated SPCE material and pressure-welded and rolled.

[0004] Patent Document 2 discloses an aluminum-clad steel sheet that uses a Cu layer made of Cu or a Cu alloy as a bonding layer. This clad material is produced by a manufacturing method in which copper plating is applied to the surface of a rolled iron material made of electrolytic iron or steel to form a copper-coated rolled iron material, an aluminum rolled material made of aluminum or an aluminum alloy is superimposed on this copper-coated rolled iron material, and then heat treatment is carried out at a temperature in the range of 300°C to 650°C in an inert or non-oxidizing atmosphere. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-30673 [Patent Document 2] Japanese Patent Application Publication No. 2-117783 Summary of the Invention [Problem to be solved by the invention]

[0006] The clad material disclosed in Patent Document 1 is produced by, for example, stacking a nickel-coated SPCE material and an aluminum material and then roll-bonding them together. However, it is unclear whether this clad material is subjected to heat treatment to create an appropriate metal diffusion layer after roll-bonding. Therefore, this clad material may not have the plastic workability (e.g., Erichsen value) required for deep drawing and other processes that involve large plastic deformation.

[0007] The clad material disclosed in Patent Document 2 is produced by, for example, separately rolling a copper-coated iron material and an aluminum material, stacking the two rolled materials, and then heat-treating them in this state at a temperature ranging from 300°C to 650°C in an inert or non-oxidizing atmosphere. In this clad material, the copper coating the iron material serves as an adhesive between the iron material and the aluminum material. The presence of copper between the iron material and the aluminum material inhibits the formation of iron (Fe) and aluminum (Al) compounds. Therefore, it is expected that copper can be used to prevent a decrease in bonding strength due to excessive formation of Fe and Al compounds. However, copper is prone to metal diffusion when heated. Therefore, this clad material may not have the plastic workability (e.g., Erichsen value) required for deep drawing and other processes that involve large plastic deformation.

[0008] An object of the present invention is to provide a conductive connecting member having a preferable Erichsen value of 5 mm or more, and more preferably 7 mm or more, which is suitable for drawing and deep drawing. [Means for solving the problem]

[0009] The inventor focused on the second metal layer made of Fe or an Fe alloy, which is the main source of mechanical strength, in a clad material in which a first metal layer made of Al or an Al alloy, a second metal layer made of Fe or an Fe alloy, and a third metal layer made of Al or an Al alloy are stacked in that order and roll-bonded, and discovered that the above-mentioned problem can be solved by appropriately controlling the content ratio of specific elements contained in this second metal layer, leading to the invention of this invention.

[0010] That is, the conductive connecting member according to the present invention is made of a clad material in which a first metal layer made of Al or an Al alloy and a second metal layer made of Fe or an Fe alloy are laminated and roll-bonded, or in which the first metal layer, the second metal layer, and a third metal layer made of Al or an Al alloy are laminated and roll-bonded in this order, and the second metal layer contains 0.50 mass% or less of Cu, thereby making it possible to obtain a conductive connecting member having a desirable Erichsen value.

[0011] Such a conductive connecting member can be produced in a manufacturing method in which a first metal plate made of Al or an Al alloy and a second metal plate made of Fe or an Fe alloy are stacked and roll-bonded, and then heat-treated to form a clad material, or in a manufacturing method in which the first metal plate, the second metal plate, and a third metal plate made of Al or an Al alloy are stacked and roll-bonded in this order, and then heat-treated to form a clad material, by limiting the Cu content of the second metal plate to 0.50 mass% or less.

[0012] In the invention relating to this conductive connecting member, the second metal layer preferably contains 0.25 mass % or less of P. This can improve the stability of the Erichsen value of the conductive connecting member.

[0013] Such a conductive connecting member can be produced by adjusting the P content of the second metal plate to 0.25 mass % or less.

[0014] In the invention relating to this conductive connecting member, the second metal layer preferably contains 0.80 mass % or less of Si, which can improve the stability of the Erichsen value of the conductive connecting member.

[0015] Such a conductive connecting member can be produced by adjusting the Si content of the second metal plate to 0.80 mass % or less.

[0016] In the invention relating to this conductive connecting member, the second metal layer preferably contains 0.05 mass % or more and 0.10 mass % or less of S. This can improve the stability of the Erichsen value of the conductive connecting member.

[0017] Such a conductive connecting member can be produced by adjusting the S content of the second metal plate to 0.05% by mass or more and 0.10% by mass or less.

[0018] In the invention relating to this conductive connecting member, the second metal layer preferably contains 0.02 mass % or less of Al, which can improve the stability of the Erichsen value of the conductive connecting member.

[0019] Such a conductive connecting member can be produced by adjusting the Al content of the second metal plate to 0.02 mass % or less.

[0020] In the invention relating to this conductive connecting member, the second metal layer preferably contains 0.01 mass % or less of Cr, which can improve the stability of the Erichsen value of the conductive connecting member.

[0021] Such a conductive connecting member can be produced by adjusting the Cr content of the second metal plate to 0.01 mass % or less. [Effects of the Invention]

[0022] According to the present invention, a conductive connecting member having a preferable Erichsen value of 5 mm or more can be provided, and if certain conditions are met, a conductive connecting member having a more preferable Erichsen value of 7 mm or more can be provided. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a diagram schematically showing a cross-sectional configuration (two-layer structure) of one embodiment of a conductive connecting member according to the present invention. [Figure 2] 1 is a diagram schematically illustrating a cross-sectional configuration (three-layer structure) of one embodiment of a conductive connecting member according to the present invention. [Figure 3] 1 is a diagram (photograph) showing a cross-sectional configuration (three-layer structure) of a conductive connecting member according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Fig. 1 is a diagram showing a cross-sectional configuration of a two-layer structure of one embodiment of a conductive connection member according to the present invention. The conductive connection member 1 shown in Fig. 1 is made of a clad material 10 in which a first metal layer 11 made of Al or an Al alloy and a second metal layer 12 made of Fe or an Fe alloy are laminated and roll-bonded.

[0025] In the clad material 10 shown in Figure 1, the first metal layer 11 has higher conductivity than the second metal layer 12, and the second metal layer 12 has higher tensile strength than the first metal layer 11. The conductive connection member 1, which utilizes the high conductivity of the first metal layer 11 and the high strength of the second metal layer 12 of this clad material 10, is an ideal member for electrical connections that require conductivity and high strength. If the first metal layer 11 is made of pure aluminum, for example, the volume resistivity of the first metal layer 11 is 2.6 x 10, which is similar to that of pure aluminum. -8 On the other hand, when the second metal layer 12 is made of pure iron containing about 99.95 mass % Fe, the volume resistivity of the second metal layer 12 is 10×10, which is approximately the same as that of pure iron. -8 Ω·m (0℃~100℃).

[0026] Fig. 2 is a diagram schematically illustrating a cross-sectional configuration of a three-layer structure, which is one embodiment of a conductive connection member according to the present invention. The conductive connection member 1 shown in Fig. 2 is composed of a clad material 10 formed by laminating and roll-bonding a first metal layer 11 made of Al or an Al alloy, a second metal layer 12 made of Fe or an Fe alloy, and a third metal layer 13 made of Al or an Al alloy in this order. For simplicity, components in Fig. 2 that correspond to those shown in Fig. 1 are denoted by the same reference numerals as in Fig. 1.

[0027] In the clad material 10 shown in Figure 2, the first metal layer 11 and the third metal layer 13 have higher conductivity than the second metal layer 12, and the second metal layer 12 has higher tensile strength than the first metal layer 11 and the third metal layer 13. The conductive connection member 1, which utilizes the high conductivity of the first metal layer 11 and the third metal layer 13 of this clad material 10 and the high strength of the second metal layer 12, is an ideal member for electrical connections that require conductivity and high strength. If the first metal layer 11 and the third metal layer 13 are made of, for example, pure aluminum, the volume resistivity of the first metal layer 11 and the third metal layer 13 is 2.6 x 10, which is similar to that of pure aluminum. -8 Ω·m (0℃~100℃).

[0028] In this invention, the term "Al" refers to pure aluminum containing 99.5% or more aluminum (Al) by mass or the element symbol, the term "Al alloy" refers to an Al-based alloy, the term "Fe" refers to pure iron containing 0.02% or less C (carbon) by mass or the element symbol, and the term "Fe alloy" refers to an Fe-based alloy.

[0029] The conductive connection member 1 made of the clad material 10 shown in Figure 1 can be obtained by manufacturing the clad material 10 shown in Figure 1 using a dissimilar metal roll-bonding process, in which a first metal plate made of Al or an Al alloy and a second metal plate made of Fe or an Fe alloy are stacked and roll-bonded, and then heat-treated (diffusion annealing) to cause appropriate metal diffusion and form the clad material.

[0030] The conductive connection member 1 made of the clad material 10 shown in Figure 2 can be obtained by manufacturing the clad material 10 shown in Figure 2 using a dissimilar metal roll-bonding process, in which a first metal plate made of Al or an Al alloy, a second metal plate made of Fe or an Fe alloy, and a third metal plate made of Al or an Al alloy are stacked in this order, roll-bonded, and then heat-treated (diffusion annealing) to cause appropriate metal diffusion and form the clad material.

[0031] The roll-bonding process for dissimilar metals described above includes manufacturing steps such as softening annealing and intermediate rolling before roll-bonding, softening annealing and intermediate rolling after roll-bonding, finish rolling to obtain the desired thickness, width, surface texture, and various properties of the target product, skin-pass rolling, annealing for stress relief, surface treatment, and strip processing, and several manufacturing steps can be selected as needed. The clad material manufactured by such manufacturing steps can be used to manufacture the conductive connecting member according to the present invention. For example, by processing this clad material into the desired shape, a conductive connecting member having the desired shape can be manufactured.

[0032] The conductive connecting member 1 (clad material 10) according to the present invention will be described below using the more complex three-layer structure shown in Fig. 2 as an example. Note that the following description is not limited to the three-layer structure shown in Fig. 2, but can also be applied to the two-layer structure shown in Fig. 1 and all other configurations within the scope of the present invention.

[0033] The clad material 10 is formed by laminating a first metal layer 11, a second metal layer 12, and a third metal layer 13 in this order. The second metal layer 12 is located between the first metal layer 11 and the third metal layer 13. A first bonding portion 12a exists between the second metal layer 12 and the first metal layer 11, and a second bonding portion 12b exists between the second metal layer 12 and the third metal layer 13. The first bonding portion 12a and the second bonding portion 12b are bonding portions that contain compounds (hereinafter referred to as "metal diffusion compounds") that are appropriately generated by metal diffusion during heat treatment (diffusion annealing) under appropriate conditions after roll bonding. Examples of metal diffusion compounds that may be generated include Fe3Al, FeAl, FeAl2, Fe2Al5, and FeAl3. Therefore, the first bonding portion 12a and the second bonding portion 12b can have sufficiently high bonding strength compared to bonding portions that contain almost no metal diffusion compounds or bonding portions that contain excessive metal diffusion compounds. The relationship between the heat treatment (diffusion annealing) conditions and the state of generation of metal diffusion compounds has been confirmed by prototypes and will be described later.

[0034] In the clad material 10, the second metal layer 12 contains 0.50 mass% or less of Cu (copper). By ensuring that the second metal layer 12 contains 0.50 mass% or less of Cu, it is possible to find appropriate heat treatment (diffusion annealing) conditions for obtaining a desirable Erichsen value of 5 mm or more. Therefore, the clad material 10 and the conductive connection member 1 formed from the clad material 10 can have a desirable Erichsen value of 5 mm or more. This point has been confirmed through prototypes, and will be described later. The conductive connection member 1 formed from the clad material 10 can be obtained by manufacturing a clad material in which the second metal plate contains 0.50 mass% or less of Cu when forming the clad material using the above-mentioned roll-bonding process of dissimilar metals, and then processing it into the desired shape.

[0035] In the clad material 10, the second metal layer 12 preferably contains 0.45 mass% or less of Cu. By containing 0.45 mass% or less of Cu in the second metal layer 12, the range of suitable heat treatment (diffusion annealing) conditions for obtaining a desirable Erichsen value of 5 mm or more can be expanded. Therefore, the clad material 10 and the conductive connection member 1 formed from the clad material 10 can more stably maintain a desirable Erichsen value of 5 mm or more. This point will also be discussed later. The conductive connection member 1 formed from the clad material 10 can be obtained by manufacturing a clad material in which the second metal plate contains 0.45 mass% or less of Cu when forming the clad material by the above-mentioned roll-bonding process of dissimilar metals, and then processing it into the desired shape.

[0036] More preferably, the clad material 10 has a second metal layer 12 containing 0.10 mass% or less Cu. By containing 0.10 mass% or less Cu in the second metal layer 12 of this clad material 10, it is possible to find appropriate heat treatment (diffusion annealing) conditions for obtaining a more preferable Erichsen value of 7 mm or more. Therefore, this clad material 10 and the conductive connection member 1 formed from this clad material 10 can have a more preferable Erichsen value of 7 mm or more. This point will also be described later. The conductive connection member 1 formed from this clad material 10 can be obtained by manufacturing a clad material in which the second metal plate contains 0.10 mass% or less Cu when forming a clad material by the above-mentioned roll-bonding process of dissimilar metals, and processing it into a desired shape.

[0037] The clad material 10 preferably has a second metal layer 12 containing 0.25 mass% or less of P (phosphorus). By having a second metal layer 12 containing 0.25 mass% or less of P, the range of suitable heat treatment (diffusion annealing) conditions for obtaining a desirable Erichsen value of 5 mm or more can be expanded. Therefore, the clad material 10 and the conductive connection member 1 formed from the clad material 10 can more stably maintain a desirable Erichsen value of 5 mm or more. This point will also be discussed later. The conductive connection member 1 formed from the clad material 10 can be obtained by manufacturing a clad material in which the second metal plate contains 0.25 mass% or less of P when forming the clad material by the above-mentioned roll-bonding process of dissimilar metals, and then processing it into the desired shape.

[0038] More preferably, the clad material 10 has a second metal layer 12 containing 0.15 mass% or less of P. By containing 0.15 mass% or less of P in the second metal layer 12 of this clad material 10, it is possible to find appropriate heat treatment (diffusion annealing) conditions for obtaining a more preferable Erichsen value of 7 mm or more. Therefore, this clad material 10 and the conductive connection member 1 formed from this clad material 10 can have a more preferable Erichsen value of 7 mm or more. This point will also be discussed later. The conductive connection member 1 formed from this clad material 10 can be obtained by manufacturing a clad material in which the second metal plate contains 0.15 mass% or less of P when forming the clad material by the above-mentioned roll-bonding process of dissimilar metals, and processing it into the desired shape.

[0039] The clad material 10 preferably has a second metal layer 12 containing 0.80 mass% or less of Si (silicon). By ensuring that the second metal layer 12 contains 0.80 mass% or less of Si, it is possible to find appropriate heat treatment (diffusion annealing) conditions for obtaining a more preferable Erichsen value of 7 mm or more. Therefore, the clad material 10 and the conductive connection member 1 formed from the clad material 10 can have a more preferable Erichsen value of 7 mm or more. This point will also be discussed later. The conductive connection member 1 formed from the clad material 10 can be obtained by manufacturing a clad material in which the second metal plate contains 0.80 mass% or less of Si when forming the clad material by the above-mentioned roll-bonding process of dissimilar metals, and then processing it into the desired shape.

[0040] More preferably, the clad material 10 has a second metal layer 12 containing 0.50 mass% or less Si. By having a second metal layer 12 containing 0.50 mass% or less Si, the range of suitable heat treatment (diffusion annealing) conditions for obtaining a more preferable Erichsen value of 7 mm or more can be expanded. Therefore, the clad material 10 and the conductive connection member 1 formed from the clad material 10 can more stably maintain a more preferable Erichsen value of 7 mm or more. This point will also be discussed later. The conductive connection member 1 formed from the clad material 10 can be obtained by manufacturing a clad material in which the second metal plate contains 0.50 mass% or less Si when forming the clad material by the above-mentioned roll-bonding process of dissimilar metals, and then processing it into the desired shape.

[0041] In the clad material 10, the second metal layer 12 preferably contains 0.05% to 0.10% by mass of sulfur (S). By containing 0.05% to 0.10% by mass of S in the second metal layer 12, the range of suitable heat treatment (diffusion annealing) conditions for obtaining a desirable Erichsen value of 5 mm or greater can be broadened. Therefore, the clad material 10 and the conductive connection member 1 formed therefrom can more stably maintain a desirable Erichsen value of 5 mm or greater. This point will also be discussed later. While iron-based alloys containing a large amount of S have good workability, iron-based alloys containing excessive S are brittle. Therefore, excessive S in the second metal layer 12 may reduce the mechanical strength of the clad material 10. Therefore, the S content in the second metal layer 12 should preferably be 0.10% by mass or less. The conductive connecting member 1 made of this clad material 10 can be obtained by manufacturing a clad material in which the S content of the second metal plate is 0.05 mass % or more and 0.10 mass % or less when forming the clad material by the above-mentioned roll-bonding process of dissimilar metals, and processing it into the desired shape.

[0042] The clad material 10 preferably has an Al (aluminum) content of 0.02 mass% or less in the second metal layer 12. By having an Al content of 0.02 mass% or less in the second metal layer 12 of the clad material 10, an appropriate amount of metal diffusion compounds is generated by heat treatment (diffusion annealing) after roll bonding. This point will also be described later. This allows for a clad material 10 with favorable bond strength at the first and second bonding portions 12a and 12b. Therefore, the clad material 10 and the conductive connection member 1 formed from the clad material 10 have a more stable Erichsen value of 7 mm or more, which is more favorable and helps to prevent defects such as breakage of the clad material 10 during and after processing. The conductive connection member 1 formed from the clad material 10 can be obtained by manufacturing a clad material with an Al content of 0.02 mass% or less in the second metal plate when forming the clad material by the above-mentioned roll bonding process of dissimilar metals, and then processing it into the desired shape.

[0043] The clad material 10 preferably has a second metal layer 12 containing 0.01% or less Cr (chromium). By containing 0.01% or less Cr in the second metal layer 12, an appropriate amount of metal diffusion compounds is generated by heat treatment (diffusion annealing) after roll bonding. This will be discussed later. This allows the clad material 10 to be obtained with favorable bond strength at the first and second bonding portions 12a and 12b. Therefore, the clad material 10 and the conductive connection member 1 formed from the clad material 10 have a more stable Erichsen value of 7 mm or more, which is more favorable and helps prevent damage to the clad material 10 during and after processing. The conductive connection member 1 formed from the clad material 10 can be obtained by manufacturing a clad material containing 0.01% or less Cr in the second metal plate when forming the clad material using the above-mentioned dissimilar metal roll bonding process, and then processing the clad material into the desired shape.

[0044] The conductive connection member 1 according to the present invention has a preferred Erichsen value of 5 mm or greater, and a more preferred Erichsen value of 7 mm or greater if certain conditions are met, allowing it to be easily formed into a desired shape. Furthermore, the conductive connection member 1 according to the present invention has a first metal layer 11 and a third metal layer 13 made of Al or an Al alloy, which have excellent conductivity and good weldability, sandwiching a second metal layer 12 made of Fe or an Fe alloy. This makes the conductive connection member 1 according to the present invention a suitable material for applications such as leads (tabs), terminals, connectors (interconnectors), and bus bars. Furthermore, the conductive connection member 1 according to the present invention can be electrically connected to connected members such as current collectors, metal separators, electrodes, or electrode terminals via the first metal layer 11 and the third metal layer 13 made of Al or an Al alloy, and is particularly capable of high-quality welding to connected members made of Al or an Al alloy.

[0045] The thickness t (total thickness) of the clad material 10 constituting the conductive connection member 1 is, for example, 0.05 mm or more and 2 mm or less when the conductive connection member 1 is intended for use as a lead (tab), terminal, connector (interconnector), bus bar, or the like. In this case, the ratio (layer ratio) of the thickness t1 of the first metal layer 11 to the thickness t2 of the second metal layer 12 to the thickness t3 of the third metal layer 13 may be, for example, 1:18:1 to 2:1:2, i.e., t1 and t3 are 1 to 2, and t2 is 1 to 18. Note that the thickness t1 of the first metal layer 11 and the thickness t3 of the third metal layer 13 may or may not be equal to each other.

[0046] Furthermore, when prioritizing the conductivity of the conductive connection member 1, it is preferable to make the thickness t1 of the first metal layer 11 and the thickness t3 of the third metal layer 13 equal to or greater than the thickness t2 of the second metal layer 12, with t1:t2:t3 being, for example, 1:1:1 to 2:1:2. When prioritizing the mechanical strength (tensile strength and yield strength) of the conductive connection member 1, it is preferable to make the thickness t2 of the second metal layer 12 equal to or greater than the thickness t1 of the first metal layer 11 and the thickness t3 of the third metal layer 13, with t1:t2:t3 being, for example, 1:1:1 to 1:18:1.

[0047] In this invention, the second metal layer 12 made of Fe or an Fe alloy can be formed by using a second metal plate made of Fe or an Fe alloy when forming the clad material 10. As described above, the Cu content of this second metal layer 12 is 0.50 mass% or less, preferably 0.45 mass% or less, and more preferably 0.10 mass% or less. To ensure that the Cu content of the second metal layer 12 is 0.50 mass% or less, a second metal plate made of Fe or an Fe alloy with a Cu content of 0.50 mass% or less is selected. To ensure that the Cu content of the second metal layer 12 is 0.45 mass% or less, a second metal plate made of Fe or an Fe alloy with a Cu content of 0.45 mass% or less is selected. To ensure that the Cu content of the second metal layer 12 is 0.10 mass% or less, a second metal plate made of Fe or an Fe alloy with a Cu content of 0.10 mass% or less is selected.

[0048] As described above, the P content of the second metal layer 12 is preferably 0.25% by mass or less, and more preferably 0.15% by mass or less. To ensure that the P content of the second metal layer 12 is 0.25% by mass or less, a second metal plate made of Fe or an Fe alloy with a P content of 0.25% by mass or less is selected. To ensure that the P content of the second metal layer 12 is 0.15% by mass or less, a second metal plate made of Fe or an Fe alloy with a P content of 0.15% by mass or less is selected.

[0049] As described above, the Si content of the second metal layer 12 is preferably 0.80% by mass or less, and more preferably 0.50% by mass or less. To ensure that the Si content of the second metal layer 12 is 0.80% by mass or less, a second metal plate made of Fe or an Fe alloy with a Si content of 0.80% by mass or less is selected. To ensure that the Si content of the second metal layer 12 is 0.50% by mass or less, a second metal plate made of Fe or an Fe alloy with a Si content of 0.50% by mass or less is selected.

[0050] As described above, the S content in this second metal layer 12 is preferably 0.05% by mass or more and 0.10% by mass or less. To ensure that the S content in the second metal layer 12 is 0.05% by mass or more and 0.10% by mass or less, a second metal plate made of Fe or an Fe alloy with an S content of 0.05% by mass or more and 0.10% by mass or less is selected.

[0051] As described above, the Al content of the second metal layer 12 is preferably 0.02 mass % or less. To ensure that the Al content of the second metal layer 12 is 0.02 mass % or less, a second metal plate made of Fe or an Fe alloy with an Al content of 0.02 mass % or less is selected.

[0052] As described above, the Cr content in the second metal layer 12 is preferably 0.01 mass % or less. To ensure that the Cr content in the second metal layer 12 is 0.01 mass % or less, a second metal plate made of Fe or an Fe alloy with a Cr content of 0.01 mass % or less is selected.

[0053] Specific examples of Fe or Fe alloys that are suitable for forming the second metal layer 12 according to the present invention and that are considered suitable for the second metal plate for forming the second metal layer 12 include pure iron such as electrolytic iron, Armco iron, carbonyl iron, and reduced iron, soft magnetic iron such as the JIS SUY series and A series, and cold-rolled steel sheets such as the JIS SPCD for drawing and the JIS SPCE, SPCF, and SPCG for deep drawing. However, none of these conventional specifications for Fe or Fe alloys take into consideration an upper limit for the Cu content.

[0054] Specifically, electrolytic iron, which is treated as pure iron, is defined, for example, in JIS-G0203:2009. Here, C, Si, Mn (manganese), P, and S are specified for electrolytic iron, but Cu, Al, and Cr are not. Furthermore, Armco iron, carbonyl iron, and reduced iron are generally controlled by specifying C, Si, Mn, P, and S, just like electrolytic iron, because they are treated as pure iron.

[0055] Furthermore, electromagnetic soft iron is specified in, for example, JIS-C2504:2000 as the SUY series (0, 1, 2, and 3) and the A series (12, 20, 60, 80, 120, and 240). Here, the SUY series specifies C, Si, Mn, P, and S, but does not specify Cu, Al, or Cr. The A series specifies C, Si, Mn, P, S, as well as Al and Ti, but does not specify Cu or Cr.

[0056] Cold-rolled steel sheets for drawing and deep drawing are specified as SPCD, SPCE, SPCF, and SPCG in JIS-G3141:2017, for example. These four types specify C, Mn, P, and S, but do not specify Cu, Al, or Cr.

[0057] As described above, pure iron such as electrolytic iron, Armco iron, carbonyl iron, and reduced iron, the SUY series of soft magnetic iron, and cold-rolled steel sheets such as SPCD, SPCE, SPCF, and SPCG do not take into consideration the control of the Cu, Al, and Cr content ratios. Furthermore, the A series of soft magnetic iron does not take into consideration the control of the Cu and Cr content ratios. Therefore, these materials are thought to have sometimes suffered from problems such as not being able to obtain the desired Erichsen value because the presence of Cu and Cr derived from the raw materials or the presence of Al derived from deoxidizers, etc., is ignored.

[0058] Therefore, in this invention, to obtain Fe or an Fe alloy suitable for the second metal plate constituting the second metal layer 12, the upper limit of the Cu content is specifically specified for each of the above-mentioned pure iron such as electrolytic iron, Armco iron, carbonyl iron, and reduced iron, soft magnetic iron such as the SUY series and A series, and cold-rolled steel sheets such as SPCD, SPCE, SPCF, and SPCG. Preferably, upper limits are also specified for the P, Si, S, Al, and Cr contents, and appropriate management is carried out based on these. In other words, in the conductive connection member 1 according to this invention, it is important to control the Cu content in the second metal layer 12 to 0.50% by mass or less. Additionally, it is preferable to control P to 0.25% by mass or less, Si to 0.80% by mass or less, S to 0.05% by mass to 0.10% by mass or less, Al to 0.02% by mass or less, and Cr to 0.01% by mass or less.

[0059] Specific examples of Al or Al alloys suitable for the first metal plate to form the first metal layer 11 include the A1000 series (pure aluminum) such as A1050 and A1100, which have excellent conductivity, as specified in JIS-H4000:2014; the A3000 series (Al-Mn based) such as A3003, which has higher strength than pure aluminum; the A4000 series (Al-Si based) such as A4032 and A4043, which has a smaller thermal expansion coefficient than pure aluminum; and the A5000 series (Al-Mg based) such as A5052, which has higher strength.

[0060] For example, A1050 is preferred because it has excellent workability, thermal conductivity, and electrical conductivity. Also, A1100 is preferred because it has excellent weldability, corrosion resistance, and formability. The volume resistivity of the A1000 series, which has excellent electrical conductivity, is 2.65 x 10 -8 The strength is about Ω·m (0°C to 100°C). A3003 is preferable because it has higher strength than pure aluminum and the same level of workability and corrosion resistance as pure aluminum. A4032 and A4043 are preferable because they have a small coefficient of thermal expansion and good wear resistance and heat resistance. A5052 is preferable because it has higher strength than the above-mentioned Al alloys and good corrosion resistance, formability, and weldability.

[0061] The Al or Al alloy suitable for the third metal plate forming the third metal layer 13 is the same as the Al or Al alloy suitable for the first metal plate forming the first metal layer 11. The Al or Al alloy forming the first metal plate and the Al or Al alloy forming the third metal plate may be the same material or different materials. In other words, the Al or Al alloy forming the first metal layer 11 and the Al or Al alloy forming the third metal layer 13 may be the same material or different materials.

[0062] Next, a prototype for verifying the effects of the present invention and the results thereof will be described.

[0063] For this prototype, we fabricated and evaluated a clad material 10 with a three-layer structure (see Figure 2), which is thought to have more layers and joints and therefore more difficult to deep-draw. A pure iron-based iron material modified by adding one of the following impurity elements was then melted and used to prepare an iron plate (Fe plate). The iron material was melted in an alumina crucible, deoxidized with Si and Mn, and no carbon was added. The melted iron material was then hot-rolled to a thickness of approximately 4 mm, and cold-rolled to a thickness of approximately 0.8 mm.

[0064] Also, an aluminum plate (Al plate) made of an Al-Si alloy (by mass %, 0.76% Si, 0.47% Fe, 0.01% Cu, 0.01% Mn, 0.01% Zn, and the balance Al) was prepared.

[0065] Next, a 0.09 mm thick Al plate (first metal plate), a 0.8 mm thick Fe plate (second metal plate), and a 0.09 mm thick Al plate (third metal plate) were stacked in this order and roll-bonded to a thickness of 0.127 mm or 0.15 mm, and then heat-treated (diffusion annealing) was performed. The heat treatment was performed with a fixed holding time of 3 hours and the holding temperature varied from 460°C to 580°C in 20°C increments to prevent melting and excessive softening of the Al layer. Heat treatment was also attempted with a fixed holding temperature of 500°C and holding times of 6, 12, and 24 hours.

[0066] This resulted in the production of clad materials 10 (prototypes No. 1 to No. 30) with a three-layer structure, in which an Al layer (first metal layer 11) made of an Al plate, an Fe layer (second metal layer 12) made of an Fe plate, and an Al layer (third metal layer 13) made of an Al plate were roll-bonded in this order.

[0067] An example of the produced conductive connection member 1 (clad material 10) is shown in Figure 3. Figure 3 is a cross-sectional image (photograph) of the conductive connection member 1 (clad material 10) cut in the thickness direction. The average thickness t of this conductive connection member 1 (clad material 10) is 0.127 mm. The ratio (layer ratio) of the average thickness t1 of the Al layer (first metal layer 11), the average thickness t2 of the Fe layer (second metal layer 12), and the average thickness t3 of the Al layer (third metal layer 13) is approximately 0.010 mm:0.111 mm:0.006 mm.

[0068] The produced conductive connection member 1 (clad material 10) has a joint (first joint 12a) containing a metal diffusion structure between one Al layer (first metal layer 11) and one Fe layer (second metal layer 12), and a joint (second joint 12b) containing a metal diffusion structure between the other Al layer (third metal layer 13) and one Fe layer (second metal layer 12). Metal diffusion compounds such as FeAl3 containing Fe and Al, which are generated by metal diffusion during heat treatment after roll bonding, are present in these joints.

[0069] Below, we will explain the relationship between the impurity elements (Si, Mn, Cu, Al, Cr, P, and S) contained in the Fe layer (second metal layer 12) made of an Fe plate made of pure iron-based iron material in the manufactured conductive connecting member 1 (clad material 10), the Erichsen value of the clad material 10, and the state of compound formation at the joint.

[0070] First, Table 1 shows the results of a component analysis of the Fe layer (Fe plate) that constitutes the conductive connection member 1 (clad material 10). The content ratios of Cu, Si, Al, Cr, and Mn can be measured using an analyzer based on ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy: ICP-AES). The content ratios of C and S can be measured using a carbon / sulfur analyzer.

[0071] As shown in Table 1, the basic components of the Fe layer (Fe plate) are, in mass%, trace amounts of Cu and P, 0.01% to 0.04% Si, trace amounts of S, Al, and Cr, 0.12% to 0.24% Mn, and 0.02% to 0.05% C. This suggests that it is generally possible to investigate the effects of intentionally changing the content ratios of impurity elements (Cu, P, Si, S, Al, Cr, and Mn) in the Fe layer (Fe plate).

[0072] [Table 1]

[0073] Next, the effects of Cu, P, Si, S, Al, Cr, and Mn contained in the Fe layer (Fe plate) on the Erichsen value of the conductive connection member 1 (clad material 10) will be described.

[0074] Table 2 shows the Erichsen values measured after performing a predetermined heat treatment (diffusion annealing) using a plurality of samples prepared from the conductive connection members 1 (clad materials 10) numbered 1 to 30 shown in Table 1. The Erichsen values were measured for the above-mentioned plurality of samples. All of the above-mentioned plurality of samples have an average thickness t of 0.15 mm (t1:t2:t3 ≒ 0.014:0.122:0.014). The notation "numerical value~numerical value" shown in Table 2, for example, the notation "June~July" of No. 1 at 500 °C means that the minimum value of the measured values of the plurality of samples of No. 1 is 6.9 mm and the maximum value is 7.2 mm. The other notations of "numerical value~numerical value" are also "minimum value~maximum value" in the same way.

[0075]

Table 2

[0076] <Effect of Cu> For Nos. 1 to 4, the content ratio of Cu contained in the Fe layer (Fe plate) was intentionally changed. According to Nos. 1 to 4, it can be confirmed that when Cu is contained in the Fe layer (Fe plate), it has a significant effect on the Erichsen value of the conductive connection member 1 (clad material 10). For example, in the case of Nos. 1 to 3 where Cu is 0.50 mass% or less, holding conditions (3 hours at 580 °C) that can obtain a preferable Erichsen value of 5 mm or more were found. However, in the case of No. 4 where Cu is 0.98 mass%, holding conditions that can obtain a preferable Erichsen value of 5 mm or more could not be found. From this, it was found that when Cu is 0.50 mass% or less, it is possible to find holding conditions that can obtain a preferable Erichsen value of 5 mm or more, but when Cu exceeds 0.50 mass%, it becomes difficult to find holding conditions that can obtain a preferable Erichsen value of 5 mm or more.

[0077] Also, compared with No. 3 with 0.46% by mass of Cu, for No. 1 and No. 2 with less than 0.46% by mass of Cu, the range of holding conditions under which a preferable Erichsen value of 5 mm or more can be obtained clearly widened. From this, it was found that when the Cu content is 0.45% by mass or less, as the Cu content ratio decreases, a preferable Erichsen value of 5 mm or more can be stably obtained.

[0078] Also, in No. 3 with 0.46% by mass of Cu, a more preferable Erichsen value of 7 mm or more could not be obtained, but for No. 1 and No. 2 with less than 0.46% by mass of Cu, holding conditions under which a more preferable Erichsen value of 7 mm or more can be obtained were found. For example, when the holding time is 3 hours, in No. 2 with 0.10% by mass or less of Cu, a more preferable Erichsen value of 7 mm or more is obtained at 560 °C, and in No. 1 with a Cu content ratio smaller than that of No. 2, a more preferable Erichsen value of 7 mm or more is obtained at 540 °C and 560 °C. From this, it was found that when the range of Cu is 0.45% by mass or less, as the Cu content ratio decreases, it becomes easier to find holding conditions under which a more preferable Erichsen value of 7 mm or more can be stably obtained.

[0079] Also, in No. 1 (0.08% by mass) with 0.10% by mass or less of Cu, when the holding time is 3 hours, considering the Erichsen values at 540 °C and 580 °C, it can be said that there is a high possibility of obtaining a more preferable Erichsen value of 7 mm or more by setting the holding temperature to 550 °C or higher and 570 °C or lower. From the viewpoint of stably obtaining a more preferable Erichsen value of 7 mm or more, it was found that more preferably, the Cu content is 0.10% by mass or less.

[0080] <Effect of P> Numbers 5 to 8 are those in which the content ratio of P contained in the Fe layer (Fe plate) is intentionally changed. For all of Numbers 5 to 8, holding conditions that can obtain a preferable Erichsen value of 5 mm or more were found. From this, in the case of P, it can be said that the influence on the Erichsen value of the conductive connection member 1 (clad material 10) is smaller than that of Cu. Also, according to Numbers 5 to 8, it can be confirmed that the Erichsen value tends to decrease as the content ratio of P increases. From this, it is considered that there are holding conditions that can obtain a preferable Erichsen value of 5 mm or more as long as P is up to about 0.30 mass%. Considering the certainty of finding holding conditions that can obtain a preferable Erichsen value of 5 mm or more, it can be said that preferably P is 0.25 mass% or less, and the range of appropriate heat treatment (diffusion annealing) conditions for obtaining a preferable Erichsen value of 5 mm or more can be widened.

[0081] Also, in No. 8 where P is 0.23 mass%, a more preferable Erichsen value of 7 mm or more could not be obtained, but in No. 7 where P is less than 0.23 mass%, holding conditions (3 hours at 520°C to 580°C) that can obtain a more preferable Erichsen value of 7 mm or more were found. In No. 6, the minimum value of the Erichsen value does not reach 7 mm under any holding conditions, but it is not technically appropriate to interpret that the Erichsen value decreases inflectively due to P being about 0.06 mass%. Then, from the viewpoint of widening the range of holding conditions that can obtain a preferable Erichsen value of 5 mm or more, it can be said that preferably P is 0.20 mass% or less. Also, from the viewpoint of widening the range of holding conditions that can obtain a more preferable Erichsen value of 7 mm or more and increasing the possibility of finding appropriate holding conditions, it can be said that preferably P is 0.15 mass% or less, more preferably P is 0.10 mass% or less, and even more preferably P is 0.05 mass% or less.

[0082] <Influence of Si> Numbers 9 to 14 are those in which the content ratio of Si contained in the Fe layer (Fe plate) is intentionally changed. For all of Numbers 9 to 14, holding conditions that can obtain a preferable Erichsen value of 5 mm or more were found. From this, in the case of Si, it can be said that the influence on the Erichsen value of the conductive connection member 1 (clad material 10) is smaller than that of Cu. Also, according to Numbers 9 to 14, it can be confirmed that, generally, the Erichsen value tends to decrease as the content ratio of Si increases. From this, it is considered that the influence of Si contained in the Fe layer (Fe plate) on the Erichsen value of the conductive connection member 1 (clad material 10) is relatively small.

[0083] Also, a tendency is recognized that holding conditions for obtaining a more preferable Erichsen value of 7 mm or more are more stable when Si is less. For example, when Si is less than No. 13 (0.87 mass%), it can be confirmed that the range of holding conditions for obtaining a more preferable Erichsen value of 7 mm or more tends to widen. From this viewpoint, preferably Si is 0.80 mass% or less, and more preferably 0.50 mass% or less. Also, from the viewpoint of widening and stabilizing the range of holding conditions for obtaining a more preferable Erichsen value of 7 mm or more, preferably Si is 0.15 mass%, and more preferably Si is 0.10 mass%.

[0084] <Effect of S> Nos. 15 to 18 are those in which the content ratio of S contained in the Fe layer (Fe plate) is intentionally changed. For all of Nos. 15 to 18, holding conditions under which a preferable Erichsen value of 5 mm or more can be obtained were found. From this, in the case of S, it can be said that the influence on the Erichsen value of the conductive connection member 1 (clad material 10) is smaller than that of Cu. Also, according to Nos. 15 to 18, it can be confirmed that when the content ratio of S is small, generally, the appropriate holding temperature becomes unstable and the Erichsen value tends to be less likely to become stable. Therefore, S contained in the Fe layer (Fe plate) is considered to affect the stability of the Erichsen value of the conductive connection member 1 (clad material 10). From this, from the viewpoint of widening and stabilizing the range of holding conditions for obtaining a preferable Erichsen value of 5 mm or more, it can be said that preferably, S is 0.05 mass% or more. As described above, since there is a concern that the mechanical strength of the clad material 10 may decrease if S contained in the Fe layer (Fe plate) is excessive, preferably, S is set to 0.10 mass% or less.

[0085] <Effect of Al> Nos. 19 to 22 are those in which the content ratio of Al contained in the Fe layer (Fe plate) is intentionally changed. In Nos. 19 to 22, although Al changes from 0.02 mass% to 0.48 mass% (change width 0.46 mass%), holding conditions under which a more preferable Erichsen value of 7 mm or more can be obtained were found for all of them. From this, in the case of Al, it can be said that the influence on the Erichsen value of the conductive connection member 1 (clad material 10) is smaller than that of Cu, P, Si, and S. Also, according to Nos. 19 to 22, it can be confirmed that as the content ratio of Al increases, the range of holding temperatures at which a preferable Erichsen value of 5 mm or more can be obtained tends to become narrower. Also, in No. 22 where Al is 0.48 mass%, the Erichsen value did not reach 5 mm under the holding conditions of 500 °C for 6 hours. From this, from the viewpoint of stably obtaining a preferable Erichsen value of 5 mm or more and further widening the range of holding conditions for obtaining a more preferable Erichsen value of 7 mm or more, it can be said that preferably, Al is 0.45 mass% or less, more preferably 0.20 mass% or less, and most preferably 0.02 mass% or less.

[0086] <Effect of Cr Samples No. 23 to 26 have intentionally varied the Cr content ratio in the Fe layer (Fe plate). In Samples No. 23 to 26, Cr varies from 0.01% by mass to 0.33% by mass (change range 0.32% by mass), and in all cases, holding conditions that can obtain more preferable Erichsen values of 7 mm or more were found. From this, in the case of Cr, it can be said that the influence on the Erichsen value of the conductive connection member 1 (clad material 10) is smaller compared to Cu, P, Si, and S. Also, according to Samples No. 23 to 26, it can be confirmed that as the Cr content ratio increases, the range of holding temperatures at which preferable Erichsen values of 5 mm or more can be obtained tends to become narrower. Also, in Samples No. 25 and No. 26 where Cr is 0.14% by mass or more, the Erichsen value did not reach 5 mm under the holding conditions of 500 °C for 6 hours. From this, from the viewpoint of stably obtaining preferable Erichsen values of 5 mm or more, it can be said that preferably Cr is 0.12% by mass or less, more preferably 0.10% by mass or less, and most preferably 0.01% by mass or less.

[0087] <Effect of Mn In samples Nos. 27 to 30, the Mn content in the Fe layer (Fe plate) was intentionally varied. The Mn content in samples Nos. 27 to 30 varied from 0.31 mass% to 0.92 mass% (a variation of 0.61 mass%). In all samples, the holding conditions were found to yield a more favorable Erichsen value of 7 mm or greater. This indicates that Mn has a smaller effect on the Erichsen value of the conductive connection member 1 (clad material 10) than Cu, P, Si, and S. The variation in the Mn content was 0.15 mass% greater than Al and 0.29 mass% greater than Cr, but the Erichsen value still reached 7 mm. This indicates that Mn has a smaller effect on the Erichsen value of the conductive connection member 1 (clad material 10) than Al and Cr. Furthermore, in sample No. 29, which contained 0.66 mass% Mn, the Erichsen value did not reach 5 mm when held at 500°C for 6 hours. From this, from the viewpoint of stably obtaining a preferable Erichsen value of 5 mm or more and further expanding the range of holding conditions under which a more preferable Erichsen value of 7 mm or more can be obtained, it can be said that the Mn content is preferably 0.60 mass % or less, and more preferably 0.50 mass % or less.

[0088] Next, we will explain the effects of each of Cu, P, Si, S, Al, Cr, and Mn contained in the Fe layer (Fe plate) on the joints (first joint 12a, second joint 12b) containing metal diffusion compounds of the conductive connecting member 1 (clad material 10).

[0089] To confirm the formation of metal diffusion compounds at the joints of the conductive connection member 1 (clad material 10), a magnified observation of the surface condition of the joints was performed. Specifically, several samples were prepared from the conductive connection members 1 (clad materials 10) No. 1 to No. 30 shown in Table 1, and heat treatment (diffusion annealing) was performed under specified holding conditions. Several samples were randomly selected from the samples for measuring the Erichsen values ​​obtained by the heat treatment. The cross-sections of the selected samples in the thickness direction were polished, and the surface condition of the cross-sections was observed under magnification. The observed samples were heat treated (diffusion annealed) for 3 hours at temperatures between 460°C and 580°C (in 20°C increments).

[0090] In the enlarged observation image of the cross-section of the joint of the sample, in some samples, a pattern like spots was sometimes observed. When examining these spots, it was found that they were metal diffusion compounds composed of FeAl3 and the like. Also, it was confirmed that the occurrence pattern of these spots differed in appearance depending on elements such as Cu contained in the Fe layer (Fe plate) and the holding temperature of the heat treatment (diffusion annealing). Also, in some samples, as the holding temperature of the heat treatment (diffusion annealing) increased from a low temperature (460 °C) to a high temperature (580 °C), more spots were confirmed, and it was confirmed that an excessive amount of metal diffusion compounds was generated. From this, it can be generally understood that by comparing the appearance of the spots confirmed in the observation image, it is roughly possible to examine the influence on the occurrence pattern of metal diffusion compounds (spots) when the content ratios of impurity elements (Cu, P, Si, S, Al, Cr, and Mn) in the Fe layer (Fe plate) are intentionally changed.

[0091] <Effect of Cu> In the case of samples (No. 1 to 4) with intentionally changed Cu content ratios, almost no spots were observed at the joint. For example, even when the holding temperature was 580 °C and the Cu content ratio was the maximum of 0.98 mass% (No. 4), almost no spots occurred. In the case of general clad materials, it is known that the higher the holding temperature of the heat treatment (diffusion annealing), the more the metal diffusion progresses and the more metal diffusion compounds are generated. Considering this point, since almost no spots occurred even after heating at 580 °C for 3 hours, it can be understood that Cu contained in the Fe layer (Fe plate) does not promote the formation of metal diffusion compounds at the joint.

[0092] <Effect of P> In the case of samples (No. 5 to 8) with the intentionally changed content ratio of P, almost no spots were observed at the joint. For example, even when the holding temperature was 580 °C and the content ratio of P was the maximum of 0.23 mass% (No. 8), almost no spots occurred. Considering this point, since almost no spots occurred even when heated at 580 °C for 3 hours, it can be understood that P contained in the Fe layer (Fe plate) does not promote the formation of metal diffusion compounds at the joint, similar to Cu.

[0093] <Effect of Si> In the case of samples (No. 9 to 14) with the intentionally changed content ratio of Si, in samples (No. 9 to 11) where the content ratio of Si was less than 0.32 mass%, almost no spots occurred at the joint. However, in the sample (No. 12) with a Si content ratio of 0.32 mass%, when heated at a holding temperature of 580 °C for 3 hours, spots occurred at the joint. Also, in the sample (No. 13) with a Si content ratio of 0.87 mass% and the sample (No. 14) with a Si content ratio of 1.68 mass%, even when heated at a holding temperature of 480 °C for 3 hours, spots occurred at the joint, and the amount of spots generated increased with the increase in the holding temperature. From this, it can be understood that Si contained in the Fe layer (Fe plate), unlike Cu and P, promotes the formation of metal diffusion compounds at the joint.

[0094]

[0095] <Effect of S> ​In the case of samples (No. 15 to 18) with intentionally varied S content ratios, almost no spots were observed at the joint. For example, even when the holding temperature was 580 °C with the maximum S content ratio of 0.067 mass% (No. 18), almost no spots occurred. Considering this point, since almost no spots occurred even after heating at 580 °C for 3 hours, it can be understood that S contained in the Fe layer (Fe plate), similar to Cu and P, does not promote the formation of metal diffusion compounds at the joint.

[0096] <Effect of Al> In the case of samples (No. 19 to 22) with intentionally varied Al content ratios, in the sample with an Al content ratio of 0.02 mass% (No. 19), almost no spots occurred at the joint. However, in the sample with an Al content ratio of 0.03 mass% (No. 20), spots occurred at the joint when heated at a holding temperature of 480 °C for 3 hours, and the amount of spots generated increased with the increase in the holding temperature. And in the samples with an Al content ratio of 0.14 mass% (No. 21) and 0.48 mass% (No. 22), spots occurred at the joint even when heated at a holding temperature of 460 °C for 3 hours. From this, it can be understood that Al contained in the Fe layer (Fe plate), different from Cu and P, significantly promotes the formation of metal diffusion compounds at the joint.

[0097] As a result, it was found that it is preferable that the Al contained in the Fe layer (Fe plate) be 0.02 mass% or less from the viewpoint of sufficiently suppressing the excessive formation of metal diffusion compounds by heat treatment (diffusion annealing) after rolling bonding. Thereby, the excessive formation of metal diffusion compounds at the joint of the clad material 10 is sufficiently suppressed, and the conductive connection member 1 (clad material 10) becomes more stable in having a more preferable Erichsen value of 7 mm or more, and defects such as damage during and after processing are more likely to be suppressed.

[0098] <Effect of Cr> In the case of samples (No. 23 to 26) with the Cr content ratio intentionally changed, in samples (No. 23, 24) with a Cr content ratio of 0.01% by mass, almost no spots were generated at the joint. However, in the sample (No. 25) with a Cr content ratio of 0.14% by mass, when heated at a holding temperature of 540 °C for 3 hours, spots were generated at the joint, and the amount of spots generated increased with the increase in the holding temperature. Also, in the sample (No. 26) with a Cr content ratio of 0.33% by mass, when heated at a holding temperature of 500 °C or higher for 3 hours, spots were generated at the joint, and the amount of spots generated increased with the increase in the holding temperature. From this, it can be understood that Cr contained in the Fe layer (Fe plate) promotes the formation of metal diffusion compounds at the joint, unlike Cu and P.

[0099] As a result, it was found that Cr contained in the Fe layer (Fe plate) should preferably be less than 0.33% by mass, for example, 0.30% by mass or less, so that, if the holding conditions are selected, excessive generation of metal diffusion compounds by heat treatment (diffusion annealing) after roll bonding can be suppressed. Also, more preferably, from the viewpoint that no spots were generated, it was found that Cr contained in the Fe layer (Fe plate) should be 0.01% by mass or less. Thereby, excessive generation of metal diffusion compounds at the joint of the clad material 10 is sufficiently suppressed, and the conductive connection member 1 (clad material 10) more stably has a more preferable Erichsen value of 7 mm or more, and defects such as damage during and after processing are less likely to occur.

[0100] <Effect of Mn> In the case of samples (No. 27 to 30) with the Mn content ratio intentionally changed, almost no spots were observed at the joint. For example, even when the holding temperature was 580 °C in the sample (No. 30) with the maximum Mn content ratio of 0.92% by mass, almost no spots were generated. Considering this point, since almost no spots were generated even when heated at 580 °C for 3 hours, it can be understood that Mn contained in the Fe layer (Fe plate) does not promote the formation of metal diffusion compounds at the joint, similar to Cu and P.

Explanation of symbols

[0101] 1: Conductive connection material 10: Clad material 11: 1st metal layer 12:Second metal layer 12a: 1st joint 12b: 2nd joint 13: Third metal layer t: Thickness of clad material (total thickness) t1: thickness of the first metal layer t2: thickness of the second metal layer t3: thickness of the third metal layer

Claims

1. The clad material is made of a first metal layer made of Al or an Al alloy and a second metal layer made of an Fe alloy, which are laminated and roll-bonded together, or the clad material is made of a first metal layer, a second metal layer, and a third metal layer made of Al or an Al alloy, which are laminated and roll-bonded together in this order, The second metal layer contains 0.50% by mass or less of Cu, 0.25% by mass or less of P, 0.80% by mass or less of Si, 0.05% by mass to 0.10% by mass of S, 0.02% by mass or less of Al, 0.01% by mass or less of Cr, 0.12% by mass to 0.24% by mass of Mn, 0.02% by mass to 0.05% by mass of C, and the remainder being Fe and unavoidable impurities.

2. In a manufacturing method for forming a clad material, a first metal plate made of Al or an Al alloy and a second metal plate made of an Fe alloy are stacked and roll-bonded together, and further heat-treated, or in a manufacturing method for forming a clad material, the first metal plate, the second metal plate, and a third metal plate made of Al or an Al alloy are stacked and roll-bonded together in this order, and further heat-treated, The method for manufacturing a conductive connecting member, wherein the second metal plate contains 0.50 mass% or less Cu, 0.25 mass% or less P, 0.80 mass% or less Si, 0.05 mass% to 0.10 mass% S, 0.02 mass% or less Al, 0.01 mass% or less Cr, 0.12 mass% to 0.24 mass% Mn, 0.02 mass% to 0.05 mass% C, and the balance being Fe and unavoidable impurities.

Images