JP2020028884A - Method of manufacturing clad material, and clad material - Google Patents

Abstract

To provide a method of manufacturing a clad material, by which it is possible to make a layer constituted of stainless steel difficult to break when performing rolling so that a thickness ratio of a layer constituted of Cu or Cu alloy to the whole clad material becomes more than 60%, and the clad material.SOLUTION: A method of manufacturing a clad material 30 includes: a process in which a SUS plate 131 constituted of stainless steel, a SUS plate 132 constituted of stainless steel, and a Cu plate 133 constituted of Cu or Cu alloy are prepared, a difference between a Vickers hardness of the SUS plate 131 and a Vickers hardness of the SUS plate 132, and a Vickers hardness of the Cu plate 133 is set to be 27HV or less when preparing; and a clad rolling process in which rolling is performed in a state that the CU plate 133 is sandwiched between the SUS plate 131 and the SUS plate 132, and the SUS plate 131, the Cu plate 133 and the SUS plate 132 are laminated in this order and are joined to one another.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a clad material and a clad material, and more particularly, to a clad material in which Cu or a Cu alloy and stainless steel are roll-joined and a method for manufacturing the clad material.

  BACKGROUND ART Conventionally, a clad material in which stainless steel and Cu or a Cu alloy are roll-joined has been known (for example, see Patent Document 1).

  Patent Document 1 discloses a first layer and a third layer made of stainless steel formed by rolling and joining, and a Cu or Cu alloy formed between the first layer and the third layer. A clad material having a three-layer structure including a second layer to be formed is disclosed.

  The clad material disclosed in Patent Document 1 is used for a chassis of a mobile phone also serving as a heat sink, and a thickness ratio of a second layer made of Cu or a Cu alloy to the entire clad material in order to secure thermal conductivity. Is described.

Japanese Patent No. 6237950

  In the clad material disclosed in Patent Literature 1, to increase the thermal conductivity, the thickness ratio of the second layer made of Cu or Cu alloy to the entire clad material is considered to be greater than 60%. did. However, when the thickness ratio of the second layer made of Cu or Cu alloy is made larger, the first layer or the third layer made of stainless steel is apt to be torn, and is made of Cu or Cu alloy. It has been found that there is a problem that the second layer is exposed.

  The present invention has been made to solve the above-described problems in a clad material in which Cu or a Cu alloy and stainless steel are joined by rolling. One object of the present invention is to provide a Cu or Cu alloy. For producing a clad material capable of making a layer composed of stainless steel less likely to break when rolled so that the thickness ratio of the layer constituted by the above to the entire clad material is greater than 60%, and the clad material thereof It is to provide.

  The inventor of the present application has made intensive studies to solve the above-mentioned problems, and as a result, the difference between the hardness of each metal plate for forming the clad material is set to a predetermined value or less, so that the metal plate is formed of Cu or a Cu alloy. It has been found that it is possible to make the layer made of stainless steel difficult to break when the layer is rolled so that the thickness ratio of the layer to the entire clad material is greater than 60%. Then, the present invention has been completed.

  That is, the method for producing a clad material according to the first aspect of the present invention includes a first metal plate made of stainless steel, a second metal plate made of stainless steel, and a second metal plate made of Cu or Cu alloy. And a step of reducing the difference between the Vickers hardness of the first metal plate, the Vickers hardness of the second metal plate, and the Vickers hardness of the third metal plate to 27 HV or less during the preparation. Rolling the first metal plate with the third metal plate sandwiched between the first metal plate and the second metal plate, and forming a first metal layer made of the first metal plate, a third metal layer made of the third metal plate, and a second metal layer. A clad material in which a second metal layer made of a metal plate is laminated and joined in this order to produce a clad material, and clad rolling is performed so that the thickness ratio of the third metal layer to the entire thickness of the clad material is greater than 60%. Process and .

  In the method for manufacturing a clad material according to the first aspect of the present invention, as described above, the difference between the Vickers hardness of the first metal plate, the Vickers hardness of the second metal plate, and the Vickers hardness of the third metal plate is different. 27 HV or less. The stainless steel forming the first metal layer, the stainless steel forming the second metal layer, and the Cu or Cu alloy forming the third metal layer have a Vickers hardness difference of 27 HV or less before rolling. This makes it possible to prevent the first metal layer made of stainless steel and the second metal layer made of stainless steel from being easily broken when rolled. Then, since the first metal layer made of stainless steel and the second metal layer made of stainless steel are hardly broken, the thickness ratio of the third metal layer made of Cu or Cu alloy to the entire clad material is reduced. It becomes possible to make it larger than 60%.

  In the conventional method for manufacturing a clad material, the Vickers hardness of the third metal plate made of Cu or Cu alloy is set to the Vickers hardness of the first metal plate made of stainless steel and the Vickers hardness made of stainless steel. The Vickers hardness of the first metal plate made close to the Vickers hardness of the second metal plate or the Vickers hardness of the first metal plate made of stainless steel and the Vickers hardness of the second metal plate made of stainless steel are made of Cu or a Cu alloy By simply approaching the Vickers hardness of the third metal plate, the difference between the Vickers hardness of the first metal plate and the Vickers hardness of the second metal plate and the Vickers hardness of the third metal plate can be reliably adjusted to 27 HV or less. Not necessarily. Therefore, it is not always possible to reliably prevent the first metal layer made of the first metal plate and the second metal layer made of the second metal plate from being broken when rolling. As a result, when the thickness of the third metal layer is 60% or more, the first metal layer and the second metal layer may be broken, and the entire clad material of the third metal layer made of Cu or Cu alloy It cannot be said that it is possible to increase the thickness ratio to 60% or more.

  On the other hand, in the method for manufacturing a clad material according to the first aspect of the present invention, the difference between the Vickers hardness of the first metal plate, the Vickers hardness of the second metal plate, and the Vickers hardness of the third metal plate is 27 HV or less. To As a result, the first metal layer and the second metal layer can be prevented from being broken during the clad rolling, so that the thickness of the third metal layer made of the third metal plate made of Cu or a Cu alloy with respect to the entire clad material is reduced. The ratio can be made larger than 60%.

  Further, in the method for manufacturing a clad material according to the first aspect, as described above, a clad material in which the thickness ratio of the third metal layer made of Cu or a Cu alloy to the entire clad material is greater than 60%. Thereby, the conductivity and thermal conductivity of the clad material including the third metal layer made of Cu or Cu alloy can be increased. Further, since the front and back surfaces of the third metal layer made of Cu or Cu alloy can be covered by the first metal layer made of stainless steel and the second metal layer made of stainless steel, mechanical strength and A clad material having corrosion resistance on the front and back surfaces can be obtained. As a result, it is possible to provide a clad material that is suitable for a chassis that also serves as a conductive member for a battery and a heat sink, and that has particularly excellent thermal conductivity as compared with the related art.

  In the method for manufacturing a clad material according to the first aspect, preferably, the first metal plate and the second metal plate are prepared, and the first metal plate and the second metal plate are annealed when preparing the first metal plate and the second metal plate. The Vickers hardness of the plate and the Vickers hardness of the second metal plate are made smaller than before annealing. General stainless steel such as austenitic stainless steel has a higher Vickers hardness than general Cu such as oxygen-free copper or general Cu alloy such as Zr-Cu alloy. Therefore, the mutual Vickers hardness of the first metal plate made of stainless steel, the Vickers hardness of the second metal plate made of stainless steel, and the Vickers hardness of the third metal plate made of Cu or Cu alloy are mutually different. It is not easy to make the difference 27 HV or less. Then, by annealing the stainless steel generally having a higher Vickers hardness than that of Cu or Cu alloy sufficiently by annealing, the first metal plate made of stainless steel and the Vickers hardness of the first metal plate made of stainless steel are formed. The difference between the Vickers hardness of the second metal plate and the Vickers hardness of the third metal plate made of Cu or Cu alloy can be easily reduced.

  In the method for manufacturing a clad material according to the first aspect, preferably, the first metal plate and the second metal plate are prepared, and the Vickers hardness of the first metal plate and the Vickers hardness of the second metal plate are set when the first metal plate and the second metal plate are prepared. Is adjusted to be equal. In order to adjust the Vickers hardness of the first metal plate and the Vickers hardness of the second metal plate to be equal, it is necessary to appropriately select the tempering condition when performing annealing or rolling, and to adjust by annealing. It is easy. In the annealing, respective annealing conditions (heat patterns and atmospheres such as temperature increase, holding temperature, temperature decrease, etc.) suitable for each type (material) of the stainless steel constituting the first metal plate and the stainless steel constituting the second metal plate. By selecting the above, each of the first metal plate and the second metal plate can be adjusted to the same (predetermined range) Vickers hardness. By setting the Vickers hardness of the first metal plate and the Vickers hardness of the second metal plate to be equal (predetermined range), the third metal plate is sandwiched between the first metal plate and the second metal plate. When rolling, the first metal plate and the second metal plate are rolled with the same elongation. As a result, a clad material having the same thickness of the first metal layer made of the first metal plate and the thickness of the second metal layer made of the second metal plate can be easily manufactured. In this case, preferably, the types of the stainless steel forming the first metal plate and the stainless steel forming the second metal plate are made equal. If the types of the first metal plate and the second metal plate are the same, the tempering conditions such as annealing can be made the same, so that the Vickers hardness of the first metal plate and the Vickers hardness of the second metal plate are reduced. Adjustment to the same (predetermined range) can be facilitated.

  Here, the Vickers hardness is equivalent to the case where the Vickers hardness is the same value, and the Vickers hardness is not the same value but a predetermined range (for example, within ± 3%, preferably ± 2%, (Preferably within ± 1%). The materials are equivalent when the composition of the first metal plate and the composition of the second metal plate are substantially the same (for example, the type symbol in the JIS standard is the same), and when the properties of the first metal plate and the second metal plate are the same. The meaning includes both the case where the properties of the metal sheet material are substantially the same (for example, the elongation at the time of rolling is within a predetermined range in consideration of the same value or the variation), and both cases.

  In the method for producing a clad material according to the first aspect of the present invention, preferably, a third metal plate is prepared, and at the time of preparation, the third metal plate is temper-rolled, and the Vickers hardness of the third metal plate is reduced. Adjust so that it becomes larger than before temper rolling. A general Cu alloy such as a general Cu or Zr-Cu alloy such as oxygen-free copper has a lower Vickers hardness than a general stainless steel such as an austenitic stainless steel. Therefore, the mutual Vickers hardness of the first metal plate made of stainless steel, the Vickers hardness of the second metal plate made of stainless steel, and the Vickers hardness of the third metal plate made of Cu or Cu alloy are mutually different. It is not easy to make the difference 27 HV or less. Therefore, Cu or Cu alloy, which generally has a lower Vickers hardness than stainless steel, is appropriately hardened by temper rolling, so that the Vickers hardness of the first metal plate made of stainless steel and the The difference between the Vickers hardness of the second metal plate and the Vickers hardness of the third metal plate made of Cu or a Cu alloy can be easily reduced.

  In the method for producing a clad material according to the first aspect, a clad material having an overall thickness of 0.5 mm or less is preferably produced. More preferably, a clad material having a total thickness of 0.2 mm or less is produced. With this configuration, the clad material is suitable for a chassis of a thin device such as a mobile phone.

  In the clad material according to the second aspect, a first metal layer made of stainless steel, a third metal layer made of Cu or a Cu alloy, and a second metal layer made of stainless steel are laminated in this order. Wherein the difference between the Vickers hardness of the first metal layer, the Vickers hardness of the second metal layer, and the Vickers hardness of the third metal layer is 175 HV or less. The thickness ratio of the third metal layer to the thickness of the first metal layer is greater than 60%. With this configuration, the conductivity and thermal conductivity of the clad material including the third metal layer made of Cu or a Cu alloy can be increased. Further, since the front and back surfaces of the third metal layer made of Cu or Cu alloy can be covered by the first metal layer made of stainless steel and the second metal layer made of stainless steel, mechanical strength and A clad material having corrosion resistance on the front and back surfaces can be obtained. As a result, it is possible to provide a clad material that is suitable for a chassis that also serves as a conductive member for a battery and a heat sink, and that has particularly excellent thermal conductivity as compared with the related art.

  The clad material according to the second aspect preferably has an overall thickness of 0.5 mm or less, more preferably an overall thickness of 0.2 mm or less, and has a total thickness of not more than 0.2 mm from the surfaces of the first metal layer and the second metal layer. 3 This is a clad material in which the metal layer is not exposed. With such a configuration, the entire thickness of the clad material is small, so that it can be used for a chassis of a thin device such as a mobile phone. Further, since the third metal layer is not exposed, it is possible to suppress corrosion of Cu or a Cu alloy constituting the third metal layer and formation of an oxide film. As a result, it is possible to suppress a decrease in conductivity and thermal conductivity due to corrosion of the third metal layer or formation of an oxide film.

  ADVANTAGE OF THE INVENTION According to this invention, when it rolls so that the thickness ratio of the layer comprised by Cu or Cu alloy with respect to the whole clad material may be larger than 60%, it will become difficult to break the layer comprised by stainless steel. Therefore, it is possible to provide a method of manufacturing a clad material capable of increasing the thickness ratio of a layer made of Cu or a Cu alloy as compared with the related art and a clad material thereof.

1 is a schematic exploded perspective view of a portable device using a clad material as a chassis according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a structure of a clad material (chassis) according to the embodiment of the present invention. It is a mimetic diagram for explaining a process of preparing a SUS board used for a clad material by an embodiment of the present invention. It is a mimetic diagram for explaining a process of preparing a Cu board used for a clad material by an embodiment of the present invention. It is a mimetic diagram for explaining a process of manufacturing a clad material according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of mobile device)
First, a schematic configuration of a portable device 100 according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the mobile device 100 according to the present embodiment includes an upper housing 1a, a display 2, a chassis 3, a substrate 4, a battery 5, and a lower housing 1b. The display 2, the chassis 3, the substrate 4, and the battery 5 are arranged in the lower housing 1b in this order from above (Z1 side). The lower housing 1b is covered by the upper housing 1a from above.

  The display 2 includes a liquid crystal display, an organic EL display, or the like, and has a function of displaying an image on the upper surface on the Z1 side.

  The chassis 3 has a function of ensuring the mechanical strength of the portable device 100 and a function of releasing heat from the display 2, the substrate 4 (the electronic component 4a) and the battery 5 to the outside. That is, the chassis 3 also functions as a heat sink.

  The board 4 is arranged on the X1 side of the lower housing 1b, and the battery 5 is arranged on the X2 side. An electronic component 4a such as a CPU (Central Processing Unit) for driving application software is arranged on the upper surface on the Z1 side of the substrate 4.

(Configuration of chassis (cladding material))
As shown in FIG. 2, the chassis 3 has a SUS layer 31 made of stainless steel, a Cu layer 33 made of Cu or a Cu alloy, and a SUS layer 32 made of stainless steel laminated in this order and joined. And a clad material 30 having a three-layer structure. The Cu layer 33 is roll-bonded to the lower surface of the SUS layer 31 on the Z2 side and is roll-bonded to the upper surface of the SUS layer 32 on the Z1 side. That is, the Cu layer 33 is sandwiched between the SUS layer 31 and the SUS layer 32. At the interface Ia between the SUS layer 31 and the Cu layer 33 and the interface Ib between the Cu layer 33 and the SUS layer 32, the layers are firmly joined by forming an atomic bond by diffusion annealing. Here, the SUS layer 31, the SUS layer 32, and the Cu layer 33 are examples of the “first metal layer”, the “second metal layer”, and the “third metal layer”, respectively, of the present invention.

  The thickness t1 of the clad material 30 in the Z direction is not particularly limited. In the present embodiment, the thickness t1 of the chassis 3 is preferably equal to or less than 0.5 mm in order to suppress the increase in the thickness in the Z direction in consideration of the weight reduction and compactness of the portable device 100. More preferably, the thickness t1 of the chassis 3 is 0.2 mm or less. In order to secure the mechanical strength of the chassis 3, the thickness t1 of the chassis 3 is preferably equal to or greater than 0.05 mm, and more preferably equal to or greater than 0.1 mm.

  The ratio (t2: t4: t3) of the thickness t2 of the SUS layer 31, the thickness t4 of the Cu layer 33, and the thickness t3 of the SUS layer 32 in the clad material 30 is not particularly limited. From the viewpoint of improving the thermal conductivity of the chassis 3, t4 is preferably larger than 60% of the entire thickness of the clad material 30, and more preferably larger than 65%, 70% or 75%. . Further, from the viewpoint of securing the mechanical strength of the chassis 3, it is preferable that t4 be smaller, such as 90% or less, 85% or less, or 80% or less of the entire clad material 30. In consideration of the balance between the improvement in the thermal conductivity of the chassis 3 and the securing of the mechanical strength, t4 is preferably larger than 60% and not more than 80% of the thickness of the entire clad material 30. In order to equalize the degree of elongation during rolling on both sides in the Z direction, the thickness t2 of the SUS layer 31 made of stainless steel and the thickness t3 of the SUS layer 32 made of stainless steel should be approximately equal. preferable.

  The type (material) of the stainless steel forming the SUS layer 31 and the stainless steel forming the SUS layer 32 is not particularly limited as long as it is stainless steel, such as austenitic, ferritic, and martensitic. Here, in the portable device 100 including the electronic component 4a (see FIG. 1), it is not preferable that the chassis 3 be magnetized. Therefore, the stainless steel forming the SUS layer 31 and the stainless steel forming the SUS layer 32 are preferably austenitic stainless steels, and more preferably so-called SUS300 (JIS) austenitic stainless steels. . The stainless steel forming the SUS layer 31 and the stainless steel forming the SUS layer 32 include, for example, Cr of 10% by mass to 18% by mass, Ni of 12% by mass to 15% by mass, and 2% by mass of 3% by mass. It contains Mo by mass% or less, unavoidable impurities including C, and the balance iron. Alternatively, the stainless steel constituting the SUS layer 31 and the stainless steel constituting the SUS layer 32 do not contain Mo, and may contain 5% by mass or more and 10% by mass or less of Ni and metals such as Mn and Cu. Good. Further, the SUS layer 31 and the SUS layer 32 are not limited to the same composition, but are preferably made of stainless steel having the same composition (material) in consideration of rolling stability and the like.

  The Cu layer 33 is made of a C1000-based (JIS standard) Cu or a C2000-based (JIS standard) Cu alloy having excellent conductivity and thermal conductivity. In addition, as Cu, there are so-called oxygen-free copper, phosphorus deoxidized copper, tough pitch copper, and the like. Further, as the Cu alloy, a Zr—Cu alloy or the like that has higher mechanical strength than Cu but easily obtains appropriate elongation is preferable. Note that Cu or a Cu alloy constituting the Cu layer 33 generally has higher conductivity and thermal conductivity than the stainless steel constituting the SUS layer 31 and the stainless steel constituting the SUS layer 32, and has high ductility. .

  Here, the difference (ΔHV) between the Vickers hardness of the SUS layer 31 and the Vickers hardness of the SUS layer 32 and the Vickers hardness of the Cu layer 33 constituting the clad material 30 of the present embodiment is 175 HV or less. The difference (ΔHV) between the Vickers hardnesses of the SUS layer 31 and the SUS layer 32 and the Cu layer 33 is preferably 170 HV or less, more preferably 165 HV or less. The difference (ΔHV) between the Vickers hardness of the SUS layer 31 and the Vickers hardness of the SUS layer 32 and the composition of the stainless steel used for the cladding material 30, the composition of Cu or Cu alloy, and the production of the cladding material 30 are determined. It is considered that the temperature varies depending on the annealing temperature or rolling ratio at the time. The inventor of the present application has reported that the SUS layer 31 and the SUS layer 32 are not broken, and the clad material 30 having a small difference (ΔHV) in Vickers hardness between the SUS layer 31 and the SUS layer 32 and the Cu layer 33 is not broken. It has been confirmed by an experiment (example) described later that the exposure of 33 can be suppressed. Here, the Vickers hardness can be measured using a general Vickers tester. The Vickers tester creates a permanent pyramid-shaped depression on the surface of the sample with a square pyramid-shaped diamond indenter (diagonal angle α ≒ 136 degrees), calculates the test load and the average value of the diagonal length of the two depressions. Vickers hardness can be calculated.

(Outline of manufacturing method of clad material 30)
First, a method of manufacturing the clad material 30 according to one embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 3, a band-shaped SUS plate 131 made of stainless steel and a band-shaped SUS plate 132 made of stainless steel are prepared. The type of the stainless steel forming the SUS plate 131 and the type of the stainless steel forming the SUS plate 132 may be the same or different, and are not particularly limited. The stainless steel forming the SUS plate 131 and the stainless steel forming the SUS plate 132 are preferably of the same type. By making the stainless steel constituting the SUS plate 131 and the stainless steel constituting the SUS plate 132 the same, processing conditions such as annealing and rolling can be made uniform.

  The SUS plate 131 and the SUS plate 132 are sufficiently annealed (softening annealing) by the annealing furnace 101 as shown in FIG. The annealing temperature varies depending on the type of stainless steel forming the SUS plate 131 and the type of stainless steel forming the SUS plate 132, but is 700 ° C. or higher for general stainless steel. It is preferable that the SUS plate 131 and the SUS plate 132 be sufficiently annealed to reduce their respective Vickers hardnesses. It is preferable that the SUS plate 131 and the SUS plate 132 after annealing both have a Vickers hardness of 140 HV or less. The SUS plate 131 and the SUS plate 132 are examples of the “first metal plate” and the “second metal plate” in the claims, respectively.

  Then, the tempered rolling is performed on the annealed SUS plate 131 and SUS plate 132 using the rolling roller 102 as necessary, so that the thickness of the SUS plate 131 and the SUS plate 132 is appropriately adjusted. In this case, the number of passes and the rolling ratio (rolling reduction) of the temper rolling can be appropriately selected.

  Further, as shown in FIG. 4, a strip-shaped Cu plate 133 made of Cu or a Cu alloy is prepared. Then, the Cu plate 133 is sufficiently annealed (softening annealing) using the annealing furnace 101 whose inside is set to a temperature exceeding the recrystallization temperature (for example, 220 ° C.) of Cu or a Cu alloy constituting the Cu plate 133. )I do. Thereby, the internal distortion due to the work hardening of the Cu plate 133 before annealing is removed, and the structure of the Cu plate 133 after annealing is sufficiently softened. The Cu plate 133 is an example of the “third metal plate” in the claims.

  Then, the thickness of the Cu plate 133 is appropriately adjusted by subjecting the annealed Cu plate 133 to temper rolling using the rolling roller 102 as necessary. In this case, the number of passes and the rolling ratio (rolling reduction) of the temper rolling can be appropriately selected. When temper rolling is performed on the Cu plate 133 after annealing, the Cu plate 133 is work-hardened due to accumulation of internal stress (strain). By performing temper rolling using this work hardening, the Vickers hardness of the Cu plate 133 can be increased. Therefore, when the Vickers hardness of the Cu plate 133 after annealing is excessively small compared to the Vickers hardness of the SUS plate 131 and SUS plate 132 after annealing and, if necessary, temper rolling, the SUS plate Temper rolling is performed on the annealed Cu plate 133 so that the difference between the Vickers hardness of 131 and the SUS plate 132 is further reduced.

  When temper rolling is performed on the Cu plate 133 after annealing, the difference (ΔHV) between the Vickers hardness of the SUS plate 131 and the Vickers hardness of the SUS plate 132 and the Vickers hardness of the Cu plate 133 is 27 HV or less. It is prepared as follows. The upper limit of the difference (ΔHV) between the Vickers hardnesses of the SUS plate 131, the SUS plate 132, and the Cu plate 133 is preferably 27 HV, and furthermore, such as 26 HV, 25 HV, 24 HV, 23 HV, 22 HV, 21 HV, 20 HV. The smaller is more preferable.

  As shown in FIG. 5, the prepared SUS plate 131, SUS plate 132, and Cu plate 133 after annealing and, if necessary, temper rolling, are SUS plate 131, Cu plate 133, and SUS plate 132 in this order. In the state of lamination, clad rolling is performed by using a rolling roller 103 to perform rolling and joining. In this case, the longitudinal direction of the band-shaped SUS plate 131, the Cu plate 133, and the SUS plate 132 is the rolling direction (transport direction). Thus, the band-shaped SUS plate 131, the Cu plate 133, and the SUS plate 132 are joined (rolled-joined) to each other in a state of being stacked in this order, and the band-shaped press-contact material 130a having a predetermined thickness can be manufactured. In addition, the number of passes and the rolling ratio (reduction ratio) of the clad rolling can be appropriately selected. At this time, the thickness of each of the SUS plate 131, the Cu plate 133, and the SUS plate 132 is appropriately reduced by clad rolling to form the press-contact material 130a having a predetermined thickness. The thickness of each of the SUS plate 131, the Cu plate 133, and the SUS plate 132 before the press-contact material 130a is manufactured is determined by the SUS layer 31, the Cu layer 33, and the It can be appropriately selected according to the thickness ratio (t2: t4: t3) of the SUS layer 32.

  Then, annealing is performed using an annealing furnace 104 whose interior is set to a temperature (about 800 ° C. or more and about 950 ° C.) exceeding the recrystallization temperature of the stainless steel constituting the SUS plate 131 and the SUS plate 132. Thereby, the structure of the SUS plate 131 and the SUS plate 132 is softened, and the structure of the Cu plate 133 is sufficiently softened to, for example, about 50 HV or more and 60 HV or less depending on the material. Further, at the interface Ic between the SUS plate 131 and the Cu plate 133 and the interface Id between the Cu plate 133 and the SUS plate 132, interatomic bonding occurs due to the diffusion treatment. Thereby, it is possible to manufacture the press-contact member 130a in a state where the interface member Ic and the interface Id are firmly diffusion-bonded.

  Then, the press-contact material 130b that has been annealed after the clad rolling is subjected to intermediate rolling (the number of passes can be selected as appropriate) using the rolling roller 105 to produce the press-contact material 130b. The pressed material 130b after the intermediate rolling becomes thinner and harder than the pressed material 130a. The Cu plate 133 constituting the press-contact member 130b also has a smaller thickness and hardens due to accumulation of internal stress (strain) than when the press-contact member 130a was formed. The thickness of the Cu plate 133 or the like is determined, for example, by embedding a specimen cut out to a length of 150 mm or more in the longitudinal direction into a resin to prepare a cross section, observing the cross section of the specimen with an optical microscope, and observing the observed specimen. The thickness can be determined by measuring the thickness at arbitrary 10 locations in the cross section and averaging a plurality of obtained thicknesses.

  Thereafter, the annealing furnace 106 whose inside is set to a temperature (about 800 ° C. or more and about 950 ° C.) higher than the recrystallization temperature of the stainless steel forming the SUS plate 131 and the SUS plate 132 is applied to the pressed material 130b after the intermediate rolling. By performing the annealing using the material, the pressure contact member 130 can be manufactured. The structure of the SUS plate 131 and the SUS plate 132 of the pressing member 130 is softened, and the structure of the Cu plate 133 is sufficiently softened to, for example, about 50 HV or more and 60 HV or less depending on the material. Thereafter, temper rolling (finish rolling) for adjusting the overall thickness and hardness is performed on the press-contact material 130. Note that the temper rolling (finish rolling) for the press-contact material 130 can be performed as necessary. Further, finishing steps such as shape correction, slit cutting, and press working can be performed as necessary. As described above, the clad material 30 shown in FIG. 2, that is, the clad material 30 in which the SUS layer 31, the Cu layer 33, and the SUS layer 32 are laminated and joined in this order can be manufactured.

<Effect of this embodiment>
In the present embodiment, the following effects can be obtained.

  In the present embodiment, as described above, the difference (ΔHV) between the Vickers hardness of the SUS plate 131 and the Vickers hardness of the SUS plate 132 and the Vickers hardness of the Cu plate 133 is 27 HV or less. The stainless steel forming the SUS layer 31 and the stainless steel forming the SUS layer 32 and the Cu or Cu alloy forming the Cu layer 33 have a Vickers hardness difference (ΔHV) of 27 HV or less before rolling. This makes it possible to make the SUS layer 31 made of stainless steel and the SUS layer 32 made of stainless steel less likely to break when rolled. The SUS layer 31 made of stainless steel and the SUS layer 32 made of stainless steel are hardly torn, so that the entire clad material 30 of the Cu layer 33 (thickness t4) made of Cu or Cu alloy is formed. The thickness ratio (t4 / t1 × 100) to the thickness (t1) can be made larger than 60%.

  In the present embodiment, the clad material 30 in which the thickness ratio (t4 / t1 × 100) of the Cu layer 33 to the entire clad material 30 is larger than 60% is manufactured. Thereby, the conductivity and thermal conductivity of the clad material 30 including the Cu layer 33 made of Cu or Cu alloy can be increased. Further, the front and back surfaces of the Cu layer 33 made of Cu or a Cu alloy (the Z1 side surface and the Z2 side surface of the clad material 30 shown in FIG. 2) are made of a SUS layer 31 made of stainless steel and stainless steel. Since the SUS layer 32 can be covered with the SUS layer 32, the clad material 30 having mechanical strength and corrosion resistance of the front and back surfaces can be obtained. As a result, it is possible to provide a clad material 30 which is suitable for the chassis 3 which also serves as a conductive member for a battery and a heat sink and which has particularly excellent thermal conductivity as compared with the related art.

  In the present embodiment, the SUS plate 131 and the SUS plate 132 are prepared, and the SUS plate 131 and the SUS plate 132 are annealed at the time of the preparation, so that the Vickers hardness of the SUS plate 131 and the SUS plate 132 is smaller than before the annealing. I do. The Vickers hardness of the stainless steel plate 131 made of stainless steel and the SUS plate made of stainless steel are obtained by sufficiently softening stainless steel generally having a higher Vickers hardness than Cu or Cu alloy by annealing. It is possible to easily reduce the difference (ΔHV) between the Vickers hardness of the 132 and the Vickers hardness of the Cu plate 133 made of Cu or a Cu alloy.

  In this embodiment, the SUS plate 131 and the SUS plate 132 are prepared, and the Vickers hardness of the SUS plate 131 and the Vickers hardness of the SUS plate 132 are adjusted at the time of preparation. By equalizing the Vickers hardness of the SUS plate 131 and the Vickers hardness of the SUS plate 132, the SUS plate 131 and the SUS plate 132 are rolled when the Cu plate 133 is rolled between the SUS plate 131 and the SUS plate 132. Are rolled at the same elongation. As a result, the clad material 30 having the same thickness of the SUS layer 31 made of the SUS plate 131 and the thickness of the SUS layer 32 made of the SUS plate 132 can be easily manufactured. In this case, preferably, the types of stainless steel forming the SUS plate 131 and the stainless steel forming the SUS plate 132 are made equal. If the types of the SUS plate 131 and the SUS plate 132 are the same, the tempering conditions such as annealing can be made the same, so that the Vickers hardness of the SUS plate 131 and the Vickers hardness of the SUS plate 132 are adjusted to be equal. Can be facilitated.

  In the present embodiment, the Cu plate 133 is prepared, and at the time of preparation, the Cu plate 133 is temper-rolled, so that the Vickers hardness of the Cu plate 133 is adjusted to be larger than before the temper rolling. Compared to stainless steel, Cu or Cu alloy having a small Vickers hardness is appropriately hardened by temper rolling, so that the SUS plate 131 made of stainless steel is made of Vickers hardness and stainless steel. The difference (ΔHV) between the Vickers hardness of the SUS plate 132 and the Vickers hardness of the Cu plate 133 made of Cu or a Cu alloy can be easily reduced.

  In the present embodiment, preferably, the clad material 30 having an overall thickness of 0.5 mm or less is manufactured. More preferably, a clad material 30 having an overall thickness of 0.2 mm or less is produced. With this configuration, the clad material 30 is suitable for the chassis 3 of a thin device such as a mobile phone.

  In the present embodiment, the clad material 30 is formed by stacking a SUS layer 31 made of stainless steel, a Cu layer 33 made of Cu or Cu alloy, and a SUS layer 32 made of stainless steel in this order. The difference between the Vickers hardness of the SUS layer 31 and the difference (ΔHV) between the Vickers hardness of the SUS layer 32 and the Vickers hardness of the Cu layer 33 is 175 HV or less. The thickness ratio (t4 / t1 × 100) of the Cu layer 33 (thickness t4) to the entire thickness (t1) is larger than 60%. With this configuration, the conductivity and thermal conductivity of the clad material 30 including the Cu layer 33 made of Cu or a Cu alloy can be increased. Further, the front and back surfaces of the Cu layer 33 made of Cu or a Cu alloy (the Z1 side surface and the Z2 side surface of the clad material 30 shown in FIG. 2) are made of a SUS layer 31 made of stainless steel and stainless steel. Since the SUS layer 32 can be covered with the SUS layer 32, the clad material 30 having mechanical strength and corrosion resistance of the front and back surfaces can be obtained. As a result, it is possible to provide a clad material 30 which is suitable for the chassis 3 which also serves as a conductive member for a battery and a heat sink and which has particularly excellent thermal conductivity as compared with the related art.

  In the present embodiment, the clad material 30 has an overall thickness of 0.5 mm or less, more preferably an overall thickness of 0.2 mm or less, and the Cu layer 33 extends from the surfaces of the SUS layer 31 and the SUS layer 32. Can be provided without exposing the clad material 30. With this configuration, since the thickness of the entire clad material is small, it can be used for the chassis 3 of a thin device such as a mobile phone. In addition, since the Cu layer 33 is not exposed, corrosion of Cu or a Cu alloy constituting the Cu layer 33 and formation of an oxide film can be suppressed. As a result, it is possible to suppress a decrease in conductivity and thermal conductivity due to corrosion of the third metal layer or formation of an oxide film.

(Example)
Next, with reference to FIGS. 2 to 5, an example (experiment) regarding the measurement of Vickers hardness and the presence / absence of exposure of the Cu layer 33 performed to confirm the effect of the present invention will be described.

  In the first embodiment, the ratio of the SUS layer 31: Cu layer 33: SUS layer 32 is set to 1: 6: 1, and the thickness ratio (t4 / thickness t4) of the Cu layer 33 (thickness t4) to the entire cladding material 30 (thickness t1). The clad material 30 was manufactured such that (t1 × 100) became 75%. As the SUS plate 131 corresponding to the SUS layer 31 and the SUS plate 132 corresponding to the SUS layer 32, 17% by mass of Cr, 8% by mass of Ni, 3% by mass of Mn, 3% by mass of Cu, balance Fe and inevitable impurities A stainless steel plate composed of stainless steel was prepared. As the Cu plate 133 corresponding to the Cu layer 33, a copper plate made of oxygen-free copper (C1020, JIS standard) was prepared. The thickness of each of the SUS plate 131 and the SUS plate 132 was 0.1 mm. The thickness of the Cu plate 133 was 0.6 mm.

  The Vickers hardness and thickness of the SUS plate 131 and the SUS plate 132 were adjusted by performing softening annealing at 1050 ° C. for 5 minutes and then performing temper rolling at a rolling reduction of 5%. The Vickers hardness and thickness of the Cu plate 133 were adjusted by performing softening annealing at 500 ° C. for 5 minutes and then temper rolling at a reduction of 70%. In Example 1, the Vickers hardness of the SUS plate 131 and the SUS plate 132 was adjusted to 140.4 HV. The Vickers hardness of the Cu plate 133 was adjusted to 118.5 HV. The Vickers hardness is obtained by measuring the Vickers hardness at five places on the SUS plate 131 and the Vickers hardness at five places on the Cu plate 133 and expressing the average of the Vickers hardness at three places excluding the maximum value and the minimum value. In Example 1, the difference (ΔHV) in Vickers hardness was 21.9 HV.

  Next, clad rolling was performed in a state where the SUS plate 131, the Cu plate 133, and the SUS plate 132 of which Vickers hardness was adjusted were laminated in this order. At this time, the rolling reduction was set to 56%. As a result, a 0.352 mm-thick press-contact material 130a was formed in which the SUS plate 131, the Cu plate 133, and the SUS plate 132 were joined (rolled-joined) in a state of being stacked in this order. In the clad rolling, the thickness of the SUS plate 131 and the SUS plate 132 after the clad rolling was set to 0.044 mm (44% of the thickness before the rolling).

  After that, the press-contact material 130a was annealed at 800 ° C. for 5 minutes, and then subjected to intermediate rolling, thereby producing a press-contact material 130b having a thickness of 0.232 mm. In the intermediate rolling, the thickness of the SUS plate 131 and the SUS plate 132 after the intermediate rolling was set to 0.029 mm (66% of the thickness before the intermediate rolling). That is, intermediate rolling was performed at a rolling reduction of 34%.

  Then, the press-bonded material 130b after the intermediate rolling was annealed at 800 ° C. for 5 minutes, and then temper rolling (finish rolling) was performed to produce the clad material 30 having a thickness of 0.2 mm. In the temper rolling (finish rolling), the thickness of the SUS plate 131 (SUS layer 31) and the SUS plate 132 (SUS layer 32) after the finish rolling was set to 0.025 mm (86% of the thickness before the finish rolling). . That is, temper rolling (finish rolling) was performed at a rolling reduction of 14%.

  In Example 2, the ratio of the SUS layer 31, the Cu layer 33, and the SUS layer 32 was set to 1: 6: 1, and the clad material 30 was manufactured so that the above-mentioned t4 / t1 × 100 became 75%. As the SUS plate 131 corresponding to the SUS layer 31 and the SUS plate 132 corresponding to the SUS layer 32, a stainless steel plate made of stainless steel composed of 16% by mass of Cr, 14% by mass of Ni, balance Fe and inevitable impurities is prepared. did. As the Cu plate 133 corresponding to the Cu layer 33, a copper plate made of oxygen-free copper (C1020, JIS standard) was prepared. The thickness of each of the SUS plate 131 and the SUS plate 132 was 0.1 mm. The thickness of the Cu plate 133 was 0.6 mm.

  The Vickers hardness of the SUS plate 131 and the SUS plate 132 was adjusted to 128.9 HV by performing soft annealing at 1050 ° C. for 5 minutes. The Vickers hardness of the Cu plate 133 was adjusted to 118.1 HV by performing softening annealing at 500 ° C. for 5 minutes and then performing temper rolling at a reduction of 70%. In Example 2, the difference (ΔHV) in Vickers hardness was 10.8 HV. Then, clad rolling, intermediate rolling, annealing, and temper rolling (finish rolling) were performed under the same conditions as in Example 1 to produce the clad material 30 of Example 2.

  In Example 3, the ratio of the SUS layer 31, the Cu layer 33, and the SUS layer 32 was set to 1: 6: 1, and the clad material 30 was manufactured so that the above-mentioned t4 / t1 × 100 became 75%. As the SUS plate 131 corresponding to the SUS layer 31 and the SUS plate 132 corresponding to the SUS layer 32, a stainless steel plate made of stainless steel composed of 16% by mass of Cr, 14% by mass of Ni, balance Fe and inevitable impurities is prepared. did. As the Cu plate 133 corresponding to the Cu layer 33, a copper plate made of oxygen-free copper (C1020, JIS standard) was prepared. The thickness of each of the SUS plate 131 and the SUS plate 132 was 0.1 mm. The thickness of the Cu plate 133 was 0.6 mm. The Vickers hardness of the SUS plate 131 and the SUS plate 132 was adjusted to 119.1 HV by performing soft annealing at 1050 ° C. for 5 minutes. The Vickers hardness of the Cu plate 133 was adjusted to 118.1 HV by performing softening annealing at 500 ° C. for 5 minutes and then performing temper rolling at a reduction of 70%. In Example 3, the difference (ΔHV) in Vickers hardness was 1.0 HV. Then, clad rolling, intermediate rolling, annealing, and temper rolling (finish rolling) were performed under the same conditions as in Example 1 to produce the clad material 30 of Example 3.

  In Example 4, the ratio of the SUS layer 31: Cu layer 33: SUS layer 32 was set to 1: 6: 1, and the clad material 30 was manufactured so that the above-mentioned t4 / t1 × 100 became 75%. As the SUS plate 131 corresponding to the SUS layer 31 and the SUS plate 132 corresponding to the SUS layer 32, 17% by mass of Cr, 8% by mass of Ni, 3% by mass of Mn, 3% by mass of Cu, balance Fe and inevitable impurities A stainless steel plate composed of stainless steel was prepared. As the Cu plate 133 corresponding to the Cu layer 33, a copper plate made of oxygen-free copper (C1020, JIS standard) was prepared. The thickness of each of the SUS plate 131 and the SUS plate 132 was 0.1 mm. The thickness of the Cu plate 133 was 0.6 mm. The Vickers hardness of the SUS plate 131 and the SUS plate 132 was adjusted to 110.7 HV by performing soft annealing at 1050 ° C. for 5 minutes. The Vickers hardness of the Cu plate 133 was adjusted to 118.1 HV by performing softening annealing at 500 ° C. for 5 minutes and then performing temper rolling at a reduction of 70%. In Example 4, the difference (ΔHV) in Vickers hardness was −7.4 HV. Then, clad rolling, intermediate rolling, and annealing were performed under the same conditions as in Example 1 to produce the clad material 30 of Example 4.

  In Comparative Example 1, the ratio of the SUS layer 31, the Cu layer 33, and the SUS layer 32 was set to 1: 6: 1, and the clad material 30 was manufactured so that the above-mentioned t4 / t1 × 100 became 75%. The SUS plate 131 corresponding to the SUS layer 31 and the SUS plate 132 corresponding to the SUS layer 32 are made of stainless steel including 18% by mass of Cr, 12% by mass of Ni, 2% by mass of Mo, balance Fe and unavoidable impurities. A stainless steel plate to be prepared was prepared. As the Cu plate 133 corresponding to the Cu layer 33, a copper plate made of oxygen-free copper (C1020, JIS standard) was prepared. The thickness of each of the SUS plate 131 and the SUS plate 132 was 0.1 mm. The thickness of the Cu plate 133 was 0.6 mm. The Vickers hardness of the SUS plate 131 and the SUS plate 132 was adjusted to 145.4 HV by performing soft annealing at 1050 ° C. for 5 minutes. The Vickers hardness of the Cu plate 133 was adjusted to 118.1 HV by performing softening annealing at 500 ° C. for 5 minutes and then performing temper rolling at a reduction of 70%. In Example 1, the difference (ΔHV) in Vickers hardness was 27.3 HV. Then, clad rolling, intermediate rolling and annealing were performed under the same conditions as in Example 1 to produce a clad material 30 of Comparative Example 1. The temperature of the annealing performed after the intermediate rolling was set to 950 ° C.

  In Comparative Example 2, the ratio of the SUS layer 31, the Cu layer 33, and the SUS layer 32 was set to 1: 6: 1, and the clad material 30 was manufactured so that the above-mentioned t4 / t1 × 100 became 75%. As the SUS plate 131 corresponding to the SUS layer 31 and the SUS plate 132 corresponding to the SUS layer 32, 17% by mass of Cr, 8% by mass of Ni, 3% by mass of Mn, 3% by mass of Cu, balance Fe and inevitable impurities A stainless steel plate composed of stainless steel was prepared. As the Cu plate 133 corresponding to the Cu layer 33, a copper plate made of oxygen-free copper (C1020, JIS standard) was prepared. The thickness of each of the SUS plate 131 and the SUS plate 132 was 0.1 mm. The thickness of the Cu plate 133 was 0.6 mm. The Vickers hardness of the SUS plate 131 and the SUS plate 132 was adjusted to 140.4 HV by performing softening annealing at 1050 ° C. for 5 minutes and then performing temper rolling at a reduction of 5%. The Vickers hardness of the Cu plate 133 was adjusted to 111.1 HV by performing softening annealing at 500 ° C. for 5 minutes and then performing temper rolling at a rolling reduction of 40%. In Comparative Example 2, the difference (ΔHV) in Vickers hardness was 29.3 HV. Then, clad rolling, intermediate rolling and annealing were performed under the same conditions as in Example 1 to produce a clad material 30 of Comparative Example 2.

  The Vickers hardness of the SUS layer 31 (SUS layer 32) and the Vickers hardness of the Cu layer 33 of the clad material 30 prepared as Examples 1 to 4, Comparative Example 1 and Comparative Example 2 were measured, and the difference between the Vickers hardness (ΔHV) was measured. ). The Vickers hardness was determined by measuring the hardness at five locations selected at random and averaging the measured values at three locations excluding the maximum and minimum values.

  Further, the produced clad material 30 was visually checked to determine whether or not the Cu layer 33 was exposed. Here, the breakage of the SUS layer 31 (SUS layer 32) depends on the deformation resistance of the SUS plate 131 (SUS plate 132 of the SUS layer 32) serving as the SUS layer 31 and the deformation resistance of the Cu plate 133 serving as the Cu layer 33. The difference is large, or inclusions (including foreign substances and the like attached to the surfaces of the SUS plate 131, the SUS plate 132, and the Cu plate 133) are present between the Cu layer 33 and the SUS layer 31 (SUS layer 32). It is caused by existence. In particular, the SUS layer 31 (the SUS layer 32) is often broken and the Cu layer 33 is exposed at a location where a rip-ring phenomenon occurs due to a large difference in the deformation resistance. Note that the lip ring means that the SUS plate 131 (SUS layer 31) or the SUS plate 132 (SUS layer 32) having higher deformation resistance is wavy in the rolling direction, so that the press-bonded material 130a after the clad rolling and the press-bonded material after the intermediate rolling. This is a phenomenon in which an undulating pattern (rip ring) is formed on the material 130b or the clad material 30 after temper rolling (finish rolling). Table 1 shows the measurement results.

  In Examples 1 to 4 in which the difference (ΔHV) in the Vickers hardness between the SUS plate 131 and the SUS plate 132 and the Cu plate 133 in the material stage was 27 or less, the Cu layer 33 was not exposed. Further, in Examples 1 to 4, the difference in Vickers hardness (ΔHV) between the Cu layer 33 of the clad material 30 and the SUS layer 31 and the SUS layer 32 as the completed product was 164.9 HV in Example 1. In Example 2, it was 159.3 HV, in Example 3, 159.0 HV, and in Example 4, 164.8 HV, which were all 165 HV or less.

  On the other hand, Comparative Examples 1 and 2 in which the difference (ΔHV) in the Vickers hardness between the SUS plate 131 and the SUS plate 132 and the Cu plate 133 at the material stage is larger than 27 are the SUS layers 31 when the intermediate rolling is performed. A lip ring phenomenon occurred in the SUS plate 131 to be formed. Therefore, the SUS plate 131 in the pressed member 130b after the intermediate rolling was broken, and the Cu plate 133 was exposed. As a result, in the clad material 30 as a finished product, the exposure of the Cu layer 33 was confirmed. In Comparative Example 1 and Comparative Example 2, the difference (ΔHV) in Vickers hardness between the Cu layer 33 and the SUS layer 31 and the SUS layer 32 of the clad material 30 as a completed product was 178.1 HV in Comparative Example 1. In Comparative Example 2, the values were 176.3 HV, which were larger than 165 HV, and exceeded 175 HV.

  From these results, in Examples 1 to 4 in which the difference (ΔHV) in Vickers hardness between the SUS plate 131 and the SUS plate 132 and the Cu plate 133 at the material stage is 27 HV or less, the SUS plate in the clad material 30 as a finished product is used. It was confirmed that exposure of the Cu layer 33 could be prevented even when the thickness of each of the layer 31 and the SUS layer 32 was as small as 0.025 mm (25 μm). When the difference (ΔHV) between the Vickers hardness of the Cu layer 33 and the SUS layer 31 and the SUS layer 32 in the clad material 30 as a finished product is 165 HV or less, the thicknesses of the SUS layer 31 and the SUS layer 32 are respectively reduced. It was confirmed that the exposure of the Cu layer 33 could be prevented even when the thickness was as small as 0.025 mm (25 μm).

  On the other hand, if the difference (ΔHV) between the Vickers hardness of the SUS plate 131 and the SUS plate 132 at the material stage and the Cu plate 133 is larger than 27 HV, the SUS layer 31 and the SUS layer 32 of the clad material 30 as a finished product It was confirmed that tearing would occur.

  It should be noted that the embodiments and examples disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments and examples, and further includes all modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the present embodiment, the clad material 30 includes a SUS layer 31 (first metal layer) made of stainless steel, a Cu layer 33 (third metal layer) made of Cu or a Cu alloy, An example is shown in which the SUS layer 32 (second metal layer) made of steel and the cladding material 30 having a three-layer structure are laminated in this order, but the present invention is not limited to this. In the present invention, for example, the cladding material 30 having a four-layer structure including a fourth layer joined to the SUS layer 31 or the SUS layer 32 on the opposite side of the Cu layer 33 from the SUS layer 31 and the SUS layer 31 and the SUS layer The cladding material 30 having a five-layer structure including a fourth metal layer and a fifth layer on the side of the layer 32 opposite to the Cu layer 33 may be used.

  Further, in the present embodiment, in order to produce the clad material 30, the tempering is performed after the softening annealing using the annealing furnace 101 shown in FIGS. 3 and 4 and before the annealing using the annealing furnace 106 shown in FIG. Although an example in which temper rolling, clad rolling, and intermediate rolling are performed has been described, the present invention is not limited to this. In the present invention, in order to manufacture the clad material 30, at least clad rolling may be performed after the softening annealing and before the annealing. In order to easily and surely perform the clad rolling, it is preferable to perform the temper rolling. In order to easily and surely produce the clad material 30 having a predetermined thickness, it is preferable to perform intermediate rolling.

  Further, in the present embodiment, an example in which the clad material 30 is used as the chassis 3 of the portable device 100 has been described, but the present invention is not limited to this. In the present invention, the clad material 30 may be used for applications other than the chassis 3 of the mobile device 100. For example, the clad material 30 of the present invention may be used for a conductive member such as a battery.

  In the present embodiment, the Vickers hardness of the Cu plate 133 is increased by temper rolling, but the present invention is not limited to this. When a Cu alloy having a Vickers hardness greater than Cu (pure copper) is used, the difference (ΔHV) in Vickers hardness between the SUS plate 131 and the SUS plate 132 is 27 HV or less without temper rolling of the Cu plate 133. It may be.

30 clad material 31 SUS layer (first metal layer)
32 SUS layer (second metal layer)
33 Cu layer (third metal layer)
100 Mobile device 131 SUS plate (first metal plate)
132 SUS plate (second metal plate)
133 Cu plate (third metal plate)

Claims (7)

A first metal plate made of stainless steel, a second metal plate made of stainless steel, and a third metal plate made of Cu or a Cu alloy are prepared. A step of reducing the Vickers hardness of the metal plate and the difference between the Vickers hardness of the second metal plate and the Vickers hardness of the third metal plate to 27 HV or less;
Rolling is performed with the third metal plate sandwiched between the first metal plate and the second metal plate, and a first metal layer made of the first metal plate and a third metal made of the third metal plate A clad material in which a layer and a second metal layer made of the second metal plate are laminated and joined in this order, and the thickness ratio of the third metal layer to the entire thickness of the clad material is more than 60%. A method for producing a clad material, the method comprising:   Preparing the first metal plate and the second metal plate, annealing the first metal plate and the second metal plate when preparing, preparing the Vickers hardness of the first metal plate and the second metal plate The method for producing a clad material according to claim 1, wherein the Vickers hardness is adjusted so as to be smaller than before annealing.   The method according to claim 1, wherein the first metal plate and the second metal plate are prepared, and the Vickers hardness of the first metal plate and the Vickers hardness of the second metal plate are adjusted when preparing the first metal plate and the second metal plate. Or the method for producing a clad material according to item 2.   The third metal plate is prepared, and the third metal plate is temper-rolled at the time of preparation, and the Vickers hardness of the third metal plate is adjusted so as to be larger than before the temper rolling. The method for producing a clad material according to any one of claims 1 to 3.   The method for producing a clad material according to any one of claims 1 to 4, wherein the clad material is rolled so as to have a total thickness of 0.5 mm or less. A clad material in which a first metal layer made of stainless steel, a third metal layer made of Cu or Cu alloy, and a second metal layer made of stainless steel are laminated and joined in this order,
A difference between the Vickers hardness of the first metal layer, the Vickers hardness of the second metal layer, and the Vickers hardness of the third metal layer is 175 HV or less;
The clad material, wherein a thickness ratio of the third metal layer to the entire thickness of the clad material is greater than 60%. The clad material according to claim 6, wherein the entire thickness of the clad material is 0.5 mm or less, and the third metal layer is not exposed from surfaces of the first metal layer and the second metal layer.

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