WO2018181717A1

WO2018181717A1 - Roll-bonded body for electronic device, and housing for electronic device

Info

Publication number: WO2018181717A1
Application number: PCT/JP2018/013245
Authority: WO
Inventors: 橋本　裕介; 貴文畠田; 功太貞木; 哲平黒川; 貴史神代
Original assignee: 東洋鋼鈑株式会社
Priority date: 2017-03-29
Filing date: 2018-03-29
Publication date: 2018-10-04
Also published as: CN108501471A; CN108501471B

Abstract

The purpose of the present invention is to provide a roll-bonded body for an electronic device, the roll-bonded body having a metal material that has excellent impact resistance while having a small thickness as a main component thereof. A roll-bonded body for an electronic device, the roll bonded body having a metal as the main component thereof, wherein the roll-bonded body for an electronic device is characterized by comprising a stainless steel layer and an aluminum alloy layer, the thickness TS (mm) and the surface hardness HS (Hv) of the stainless steel layer and the thickness TAA (mm) and the surface hardness HAA (Hv) of the aluminum alloy layer satisfying formula (1): HSTS∙2 + HAATAA∙2 ≥ 11.18, where 0.2 ≤ TS + TAA ≤ 1.6, 0.05 ≤ TS ≤ 0.6, and 0.1 ≤ TAA ≤ 1.1.

Description

Rolled joint for electronic equipment and casing for electronic equipment

The present invention relates to a rolled joined body for electronic equipment and a casing for electronic equipment.

The casing of a mobile electronic device (mobile terminal) represented by a mobile phone or the like is made of a resin such as ABS or a metal material such as aluminum. In recent years, with the increase in functionality of electronic devices, the battery capacity and the number of mounting points inside the device have increased, and it is required to secure more mounting space. In order to secure more mounting space, further thinning of the housing is essential.

Patent Documents

1 and 2 disclose an electronic device casing made of resin. When resin is used as the casing, there is a problem that it is lightweight but cannot have a metallic appearance, so that a high-class feeling cannot be produced. In addition, since the resin casing is inferior in tensile strength, elastic modulus, and impact resistance compared to a metal casing, it is necessary to increase the thickness of the casing in order to improve these characteristics. However, as described above, there is a problem that the mounting space is reduced when the casing is thick.

Also, cracks may occur depending on the magnitude of impact applied to the housing. Furthermore, there is a problem in securing electromagnetic wave shielding properties and taking an electrical ground, and it is necessary to vapor-deposit a metal inside the resin casing or attach a metal foil, so that the recyclability is poor. In addition, the heat dissipation is also inferior to the metal housing.

Patent Document 3 discloses a housing for electronic equipment made of aluminum or an aluminum alloy. By using aluminum, it is possible to obtain an electronic device casing that is lightweight, excellent in heat dissipation, and has a metallic appearance. As a method for processing a casing made of an aluminum alloy, it is known to cut out an aluminum alloy on the inner surface side of the casing. In recent years, metal materials used for housings are required to be further reduced in weight, thickness, and size. In order to satisfy this requirement, 6000 series and 7000 series aluminum alloys that are difficult to deform are used as the aluminum alloys, but such aluminum alloys that are difficult to deform are extremely poor in press workability, and are a method of processing into a casing. However, it has been limited to machining, and it has been difficult to perform press processing that is excellent in terms of cost and productivity. In addition, since the outer surface side of the casing is inferior in corrosion resistance if aluminum is used as it is, an alumite treatment that also serves as a coloring is indispensable, and it is difficult to obtain a glossy and glossy appearance with aluminum. On the other hand, although stainless steel is a material that can provide a glossy appearance, it is difficult to apply as a casing because it is too heavy and has poor heat dissipation.

Furthermore, a rolled joined body (metal laminate material, clad material) in which two or more kinds of metal plates or metal foils are laminated is also known as a metal material. A rolled joined body is a highly functional metal material having composite characteristics that cannot be obtained by a single material. For example, a rolled joined body in which stainless steel and aluminum are laminated is being studied.

Patent Document 4 discloses a rolled joined body in which stainless steel and aluminum are laminated with improved tensile strength. Specifically, a two-layer structure of stainless steel layer / aluminum layer or first stainless steel layer / A metal laminate having a three-layer structure of an aluminum layer / second stainless steel layer, the tensile strength TS (MPa) is 200 ≦ TS ≦ 550, the elongation EL is 15% or more, and the surface hardness of the stainless steel layer A metal laminate having an HV of 300 or less is described.

Patent Document 4 discloses improvement in tensile strength and the like, but does not disclose impact resistance. Impact resistance is not a continuously applied load, but is related to the behavior when a large load is applied instantaneously, whereas the tensile strength is when a load is applied little by little in a direction parallel to the plate surface. It differs greatly in that it is the strength of. Thus, when the tensile strength is high, the impact resistance is not always high. Further, the impact resistance is also affected by the final hardness and thickness of each layer of the rolled joined body after being processed as a casing, particularly on the back surface. Therefore, a method for obtaining a rolled joined body having sufficient impact resistance in a rolled joined body of stainless steel and aluminum has not been known so far.

JP 2005-149462 A Japanese Patent No. 5581453 JP 2002-64283 A International Publication No. 2017/057665

As described above, improvement in impact resistance has not been studied so far in the case of electronic equipment mainly made of conventional metal materials and the rolled joined body of stainless steel and aluminum for electronic equipment. Accordingly, an object of the present invention is to provide a rolled joined body for electronic equipment and a casing for electronic equipment mainly made of a metal material that is excellent in impact resistance while reducing the thickness.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that in a rolled joined body of stainless steel and an aluminum alloy or pure aluminum, the surface hardness (Hv) of the stainless steel layer, the thickness of the stainless steel layer, the aluminum alloy layer Alternatively, the inventors have found that controlling four factors of the surface hardness (Hv) of the pure aluminum layer and the thickness of the aluminum alloy layer or the pure aluminum layer is important for improving the impact resistance, and completed the invention. That is, the gist of the present invention is as follows.

(1) A rolled joined body for electronic equipment mainly composed of metal,
It consists of a stainless steel layer and an aluminum alloy layer,
The thickness T _S (mm) and surface hardness H _S (Hv) of the stainless steel layer, and the thickness T _AA (mm) and surface hardness H _AA (Hv) of the aluminum alloy layer are expressed by the following formula (1).
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 11.18 (1)
However,
0.2 ≦ T _S + T _AA ≦ 1.6
0.05 ≦ T _S ≦ 0.6
0.1 ≦ T _AA ≦ 1.1
A rolled joined body for electronic equipment.
(2) The following formula (2)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 14.72 (2)
The rolled joined body for electronic equipment according to (1), wherein
(3) A rolled joined body for electronic equipment mainly composed of metal,
It consists of a stainless steel layer and a pure aluminum layer,
The thickness T _S (mm) and surface hardness H _S (Hv) of the stainless steel layer, and the thickness T _A (mm) and surface hardness H _A (Hv) of the pure aluminum layer are expressed by the following formula (3).
H _S T _S ² + H _A T _A ² ≧ 17.93 (3)
However,
0.2 ≦ T _S + T _A ≦ 1.6
0.05 ≦ T _S ≦ 0.6
0.1 ≦ _{T A} ≦ 1.1
A rolled joined body for electronic equipment.
(4) The following formula (4)
H _S T _S ² + H _A T _A ² ≧ 22.52 (4)
The rolled joined body for electronic equipment according to (3), wherein
(5) the ratio of the thickness T _S of the stainless steel layer to the total thickness of the rolling conjugate, wherein 60% or less than 10% (1) to (4) for rolling electronic device according to any one of Joined body.
(6) Surface hardness _{H S} of the stainless steel layer, wherein at least 200 380 (1) to electronic equipment rolling assembly according to any one of (5).
(7) An electronic device casing mainly made of metal,
The back and / or side surface includes a rolled joined body composed of a stainless steel layer and an aluminum alloy layer. The stainless steel layer has a thickness T _S (mm) and a surface hardness H _S (Hv), and the aluminum alloy layer has a thickness T _AA (mm ) And surface hardness H _AA (Hv) is represented by the following formula (1)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 11.18 (1)
However,
0.2 ≦ T _S + T _AA ≦ 1.2
0.05 ≦ T _S ≦ 0.6
0.1 ≦ T _AA ≦ 1.1
A housing for electronic equipment.
(8) Following formula (2)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 14.72 (2)
The electronic device casing according to (7), wherein
(9) An electronic device casing mainly made of metal,
The back and / or side includes a rolled joined body composed of a stainless steel layer and a pure aluminum layer,
The thickness T _S (mm) and surface hardness H _S (Hv) of the stainless steel layer, and the thickness T _A (mm) and surface hardness H _A (Hv) of the pure aluminum layer are expressed by the following formula (3).
H _S T _S ² + H _A T _A ² ≧ 17.93 (3)
However,
0.2 ≦ T _S + T _A ≦ 1.2
0.05 ≦ T _S ≦ 0.6
0.1 ≦ _{T A} ≦ 1.1
A housing for electronic equipment.
(10) The following formula (4)
H _S T _S ² + H _A T _A ² ≧ 22.52 (4)
The electronic device casing according to (9), wherein
(11) the ratio of the thickness T _S of the stainless steel layer to the total thickness of the rolled conjugate, housing for electronic equipment according to any one of the 60% or less than 10% (7) - (10) body.
(12) the surface hardness _{H S} of the stainless steel layer, wherein at least 200 380 or less (7) to an electronic equipment enclosure according to any one of (11).
This specification includes the disclosure of Japanese Patent Application Nos. 2017-0666268, 2017-147935, and 2017-246462, which form the basis of the priority of the present application.

According to the present invention, it is possible to obtain a rolled joined body for electronic equipment and an electronic equipment casing having excellent impact resistance. This rolled bonded body for electronic devices can be suitably used as a housing for mobile electronic devices (mobile terminals) such as smartphones and tablets using high impact resistance. Moreover, taking advantage of high impact resistance, it can also be suitably used as a part used in an electronic device such as an internal reinforcing member of a mobile electronic device.

It is a figure for demonstrating the measuring method of the deformation height about the rolling joined body which concerns on an Example and a comparative example. It is a figure for demonstrating the measuring method of the deformation height about the rolling joined body which concerns on an Example and a comparative example. 5 is a graph showing the relationship between H _S T _S ² + H _AA T _AA ² and deformation height (μm) for the rolled bonded bodies of Examples 1 to 18 and Comparative Examples 1 and 2. 4 is a graph showing the relationship between H _S T _S ² + H _A T _A ² and deformation height (μm) for the rolled bonded bodies of Examples 19 to 23 and Comparative Example 3. 1 is a perspective view showing a first embodiment of an electronic device casing according to the present invention. FIG. 3 is a cross-sectional perspective view in the X-X ′ direction of the first embodiment of the electronic device casing according to the invention.

Hereinafter, the present invention will be described in detail.
1. Rolled bonded body for electronic device The rolled bonded body for electronic device of the present invention is mainly composed of metal, and includes a stainless steel layer and an aluminum alloy layer, or a stainless steel layer and a pure aluminum layer. This rolled joined body is suitable as a housing material for various electronic devices such as mobile electronic devices, and is particularly preferably used as a material for the back and / or side surfaces of electronic devices. Here, the back surface refers to a surface on the opposite side to the side on which the display unit (the display) is provided in the housing constituting the electronic device. Note that the inside of the housing may be laminated with a metal material or a plastic material other than the rolled joined body.

The rolled joined body is composed of 2 or more layers, preferably 2 to 4 layers, more preferably 2 or 3 layers, and particularly preferably 2 layers. In a preferred embodiment, in order to obtain an appearance having a metallic luster, the rolled joined body has a stainless steel layer on the outside of the case when used as a case, and is formed by two layers of stainless steel layer / aluminum alloy layer or pure aluminum layer. Or a rolled joined body comprising three layers of a stainless steel layer / aluminum alloy layer or a pure aluminum layer / stainless steel layer. Further, in order to obtain an alumite appearance, an aluminum alloy layer or a pure aluminum layer is provided on the outside of the casing, and a rolled joined body composed of two layers of an aluminum alloy layer or a pure aluminum layer / stainless steel layer, or an aluminum alloy layer or a pure aluminum layer. A rolled joined body composed of three layers of / stainless steel layer / aluminum alloy layer or pure aluminum layer may be used. In the present invention, the configuration of the rolled joined body can be selected in accordance with the use of the rolled joined body and intended characteristics.

The stainless steel constituting the stainless steel layer is not particularly limited, and plate materials such as SUS304, SUS201, SUS316, SUS316L, SUS301, and SUS430 can be used. If the hardness of the stainless steel before the rolling joining is too hard, there is a possibility that sufficient adhesion strength at the time of rolling joining cannot be ensured. In addition, since the hardness of the stainless steel layer after the roll joining is inevitably increased, there is a possibility that it is difficult to process and form the casing or the like, which will be described later. Therefore, annealing material (BA material) or 1 / 2H material is preferable as the tempering of stainless steel before rolling joining. From the viewpoint of press workability, it is preferable to have a hardness of 3 / 4H or less, more preferably 1 / 2H or less, after the rolling joining and before forming into a housing. In the present invention, both the rolled joined body (rolled joined body for electronic equipment) before being molded into the housing, and the housing (electronic equipment housing) obtained by molding the rolled joined body. In the state, it has a hardness satisfying the relational expression described later.

As the aluminum alloy constituting the aluminum alloy layer, a plate material containing at least one additive metal element as a metal element other than aluminum can be used. The additive metal element is preferably Mg, Mn, Si and Cu. The total content of additive metal elements in the aluminum alloy is preferably more than 0.5% by mass, more preferably more than 1% by mass. The aluminum alloy preferably contains at least one additive metal element selected from Mg, Mn, Si and Cu in a total content of more than 1% by mass.

Examples of the aluminum alloy include an Al—Cu alloy (2000 series), an Al—Mn alloy (3000 series), an Al—Si alloy (4000 series), and an Al—Mg alloy (5000 series) as defined in JIS. Al-Mg-Si based alloys (6000 series) and Al-Zn-Mg based alloys (7000 series) can be used. From the viewpoint of press workability, strength, corrosion resistance and impact resistance, 3000 series, 5000 series, 6000-series and 7000-series aluminum alloys are preferable, and 5000-series aluminum alloys are more preferable from the viewpoints of balance and cost. The aluminum alloy preferably contains 0.3% by mass or more of Mg.

The pure aluminum constituting the pure aluminum layer is not particularly limited as long as it is a material in which 99.5% by mass or more is aluminum. For example, 1000 series pure aluminum specified in JIS is used. be able to.

In the present invention, the rolled joined body for electronic equipment includes the surface hardness H _S (Hv) of the stainless steel layer, the thickness T _S (mm) of the stainless steel layer, the surface hardness H _AA (Hv) of the aluminum alloy layer, or a pure aluminum layer. The surface hardness H _A (Hv) and the thickness T _AA (mm) of the aluminum alloy layer or the thickness T _A (mm) of the pure aluminum layer satisfy a specific relational expression.

The inventors of the present invention have examined elements that have a particularly large contribution to impact resistance in a rolled joined body composed of a stainless steel layer and an aluminum alloy layer or a pure aluminum layer, and conducted an impact resistance test under the test conditions described below. It was found that it is effective to control the surface hardness and thickness of each layer so as to satisfy a specific relational expression as a parameter affecting the “deformation height”.
In particular, in a rolled bonded body for electronic equipment that requires an increase in mounting capacity due to a reduction in thickness, even if the rolled bonded body is thin, for example, when it is used as the back surface of a casing, the impact resistance is 0.6 mm or less. The layer structure of the rolled joined body which is excellent in the above was specified.

Specifically, in a rolled joined body for electronic equipment composed of a stainless steel layer and an aluminum alloy layer, the thickness T _S (mm) and the surface hardness H _S (Hv) of the stainless steel layer, and the thickness T _AA (mm of the aluminum alloy layer) ) And surface hardness H _AA (Hv) is represented by the following formula (1)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 11.18 (1)
It is necessary to satisfy. By satisfying the above relational expression, it was found that the “deformation height” in the impact resistance test can be reduced to 400 μm or less, the impact resistance is high, and the housing is suitable for use.

Further, the thickness _T S of the stainless steel layer (mm) and the surface hardness _H S (Hv), and the thickness of the aluminum alloy layer _T AA (mm) and the surface hardness _H AA (Hv) is represented by the following formula (2)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 14.72 (2)
It is more preferable to satisfy. As a result, the “deformation height” is set to 340 μm or less, and it has a high impact resistance equal to or higher than that of an Al alloy (A5052, H34 material) having a thickness of 0.6 mm, and can have a glossy appearance of stainless steel. Especially suitable for use in mobile electronic device casings.

The upper limit of the value of “H _S T _S ² + H _AA T _AA ² ” is not particularly limited. However, if this value is too high, the rolled bonded body becomes thick and it may be difficult to reduce the thickness. For example, in cases of mobile electronic device casings within 300 cm ² (15 cm × 20 cm), for example, for smartphones and the like, 80 or less is preferable, more preferably 60 or less, and even more preferably 50 or less when further thinning is required. And particularly preferably 30 or less. In a case of a mobile electronic device casing exceeding 300 cm ² , for example, a casing use such as a tablet or the like, a certain thickness and strength are required.

Moreover, in the rolled joined body for electronic equipment which consists of a stainless steel layer and a pure aluminum layer, thickness T _S (mm) and surface hardness H _S (Hv) of a stainless steel layer, thickness T _A (mm) and surface of a pure aluminum layer Hardness H _A (Hv) is expressed by the following formula (3)
H _S T _S ² + H _A T _A ² ≧ 17.93 (3)
It is necessary to satisfy. By satisfying the above relational expression, it was found that the “deformation height” in the impact resistance test can be reduced to 400 μm or less, the impact resistance is high, and the housing is suitable for use.

Furthermore, the thickness T _S (mm) and the surface hardness H _S (Hv) of the stainless steel layer, and the thickness T _A (mm) and the surface hardness H _A (Hv) of the pure aluminum layer are expressed by the following formula (4).
H _S T _S ² + H _A T _A ² ≧ 22.52 (4)
It is more preferable to satisfy. As a result, the “deformation height” is set to 340 μm or less, and it has a high impact resistance equal to or higher than that of an Al alloy (A5052, H34 material) having a thickness of 0.6 mm, and can have a glossy appearance of stainless steel. Especially suitable for use in mobile electronic device casings.

The upper limit of the value of “H _S T _S ² + H _A T _A ² ” is not particularly limited, but if this value is too high, there is a concern that the rolled bonded body becomes thick and it is difficult to reduce the thickness. For example, in cases of mobile electronic device casings within 300 cm ² (15 cm × 20 cm), for example, for smartphones and the like, 80 or less is preferable, more preferably 60 or less, and even more preferably 50 or less when further thinning is required. And particularly preferably 40 or less. In cases of mobile electronic device casings exceeding 300 cm ² , for example, casing uses such as tablets, a certain degree of thickness and strength are required.

In a rolled joined body for electronic equipment comprising a stainless steel layer and an aluminum alloy layer or a pure aluminum layer ("aluminum alloy layer" and "pure aluminum layer" are collectively referred to as "aluminum layer"), the surface hardness, thickness, The present inventors consider as follows that the surface hardness and thickness of the aluminum layer are important parameters for impact resistance. Specifically, in order to obtain a rolled joined body for electronic equipment having a glossy appearance of stainless steel, when adopting a rolled joined body of a stainless steel layer and an aluminum layer in order to obtain heat dissipation, the stainless steel layer is fixed. If it is more than the thickness, specifically 0.015 mm or more if it is only a glossy appearance, there is no problem, but in the manufacturing process, a thickness of 0.05 mm or more is actually required from the viewpoint of handling. However, it turned out that there were the following problems if all the remainder was made into an aluminum layer. That is, in order to obtain a sufficient bonding strength between the stainless steel layer and the aluminum layer, a post-bonding process as described later is required. However, as a result of trials by the present inventors, it has been found that the impact resistance of the joined body of the conventional stainless steel layer and aluminum layer is significantly reduced because the aluminum layer is softened by heat treatment. It was. In other words, heat treatment is performed at a predetermined temperature in order to improve the bonding strength. This heat treatment temperature is a temperature at which the stainless steel layer is in an unrecrystallized temperature range and is not softened. It is the temperature range that is removed and softens. And when the hardness of the aluminum layer was too low, it was found that sufficient impact resistance could not be obtained unless the thickness of the aluminum layer was not less than a certain value, specifically 0.85 mm or more. However, if the aluminum layer is 0.85 mm or more, the total thickness of the rolled joined body is 0.9 mm or more, and the thickness when used as a casing becomes too thick, so that the mounting capacity inside the casing is greatly reduced. . Therefore, the stainless steel layer also needs to have a certain thickness. On the other hand, the thicker the stainless steel layer, the heavier the casing. Accordingly, in order to clear such a problem, the inventors set the hardness of the aluminum layer to a certain value or more, and further increases the thickness of the aluminum layer, increases the hardness of the stainless steel layer, For electronic equipment that has a glossy appearance of a stainless steel layer and can be thinned by controlling each parameter by finding that it is necessary to take either a thickening method or a composite means A rolled joint could be obtained.

The ratio of the thickness T _S of the stainless steel layer to the total thickness of the electronic device for rolling conjugate, the thickness of the stainless steel layer and an aluminum layer is not particularly limited as long as it satisfies the equation (1) to (4), preferably 10% It is 60% or less, more preferably 12% or more and 50% or less, and further preferably 15% or more and 50% or less. When the thickness ratio of the stainless steel layer is within this range, it is possible to obtain a casing that sufficiently secures the impact resistance of the rolled joined body and also has a sufficient heat dissipation effect by the aluminum layer. In addition, the thickness ratio of a stainless steel layer means the ratio of the sum total of the thickness of the stainless steel layer with respect to the total thickness of a rolling joining body, when two or more stainless steel layers exist in a rolling joining body. Also, the thickness ratio of the aluminum layer is the sum of the thickness of the aluminum layer with respect to the total thickness of the rolled joined body, when there are two or more aluminum layers in the rolled joined body in the casing, similarly to the thickness ratio of the stainless steel layer. Say ratio.

The total thickness of the electronic device for rolling _conjugate, T S _{+ T AA} or is represented by _T S + _{T A,,} is not particularly limited, from the viewpoint of increasing the internal implementation capacity, typically, the upper limit is 1.6mm or less, Preferably it is 1.2 mm or less, More preferably, it is 1.0 mm or less, More preferably, it is 0.8 mm or less. The lower limit is 0.2 mm or more, preferably 0.3 mm or more, more preferably 0.4 mm or more. The total thickness of the rolled joined body for electronic equipment refers to the average value of the measured values obtained by measuring the thickness at any 30 points of the rolled joined body with a micrometer.

The thickness _{T S} of the stainless steel layer, from the viewpoint of securing impact resistance during thinning is 0.05mm or 0.6mm or less. Preferably they are 0.1 mm or more and 0.5 mm or less, More preferably, they are 0.1 mm or more and 0.4 mm or less. In addition, the thickness of a stainless steel layer means the sum total of the thickness of each stainless steel layer, when a rolling joining body has two or more stainless steel layers. The thickness of the stainless steel layer of the rolled joint is obtained by obtaining an optical micrograph of the cross section of the rolled joint, measuring the thickness of the stainless steel layer at any 10 points in the optical micrograph, and saying the average value of the obtained values. .

The surface hardness H _S (Hv) of the stainless steel layer can be measured according to JIS Z 2244 (Vickers hardness test-test method) using a micro Vickers hardness meter (load 200 gf). Preferably it is 200 or more, More preferably, it is 220 or more, Most preferably, it is 230 or more. In the present invention, when the other parameters are constant, the deformation height decreases as the hardness of the stainless steel layer increases, resulting in an electronic equipment rolled bonded body having high impact resistance. Therefore, from the viewpoint of the impact resistance of the rolled joint, it is preferable that _HS is higher. On the other hand, if the stainless steel layer is too hard in the rolled joint before being molded into the housing, press forming, In particular, cracking or the like may occur during draw forming, and the moldability may be significantly reduced, which may make it difficult to mold the housing. Therefore, the hardness of the stainless steel layer is preferably 380 or less, more preferably 340 or less, and still more preferably 330 or less.

The thickness _{T AA} of the aluminum alloy layer can be applied as long as usual 0.1mm or 1.1mm or less. From the viewpoint of improving the impact resistance of the rolled joined body and securing heat dissipation and reducing the weight, it is preferably 0.12 mm to 0.9 mm, and more preferably 0.15 mm to 0.72 mm. In addition, the thickness of the aluminum alloy layer of a rolled joined body means the sum total of the thickness of each aluminum alloy layer, when a rolled joined body has two or more aluminum alloy layers. The thickness of the aluminum alloy layer of the rolled joined body is obtained by obtaining an optical micrograph of the cross section of the rolled joined body, measuring the thickness of the aluminum alloy layer at any 10 points in the optical micrograph, and the average value of the obtained values. Say.

The surface hardness H _AA (Hv) of the aluminum alloy layer is not particularly limited, but the impact resistance improves as the hardness increases. For this reason, there is no particular upper limit, but it is preferably 85 Hv or less. The lower limit is preferably 40 Hv or more, more preferably 50 Hv or more, and good impact resistance can be obtained. In the present invention, the surface hardness _{H AA} of the aluminum alloy layer is used a micro Vickers hardness meter (load 50 gf), JIS Z 2244 - can be determined according to (Vickers hardness test Test method).

The thickness _{T A} pure aluminum layer, as well as the aluminum alloy layer, is applicable as long as usual 0.1mm or 1.1mm or less. In order to improve the impact resistance of the rolled joined body, and to ensure heat dissipation and to reduce the weight, it is preferably 0.12 mm to 0.9 mm, more preferably 0.15 mm to 0.72 mm. . In addition, the thickness of the pure aluminum layer of a rolled joined body means the sum total of the thickness of each pure aluminum layer, when a rolled joined body has two or more pure aluminum layers. The thickness of the pure aluminum layer of the rolled joined body is obtained by obtaining an optical micrograph of the cross section of the rolled joined body, measuring the thickness of the pure aluminum layer at any 10 points in the optical micrograph, and the average value of the obtained values. Say.

The surface hardness _HA (Hv) of the pure aluminum layer is not particularly limited, but as the aluminum alloy is hardened, the impact resistance is improved. Therefore, there is no particular upper limit, but it is preferably 50 Hv or less. The lower limit is preferably 20 Hv or more, more preferably 25 Hv or more. In the present invention, the surface hardness _HA of the pure aluminum layer can be measured according to JIS Z 2244 (Vickers hardness test-test method) using a micro Vickers hardness meter (load 50 gf).

For a rolled joined body for an electronic device comprising a stainless steel layer and an aluminum alloy layer or a pure aluminum layer, the peel strength (180 ° peel strength, also referred to as 180 ° peel strength) as an index of adhesion strength is 60 N / 20 mm or more. It is preferable that it is preferably 80 N / 20 mm or more, particularly preferably 100 N / 20 mm or more, from the viewpoint that the rolled joined body has excellent drawing workability. In addition, in the rolling joined body which consists of 3 layers or more, it is preferable that a peel strength is 60 N / 20mm or more in each joining interface. In addition, when peel strength becomes remarkably high, since it does not peel and it will be material fracture | rupture, there is no upper limit of peel strength.

The peel strength of the rolled joined body for electronic equipment is such that a test piece having a width of 20 mm is prepared from the rolled joined body and the stainless steel layer and aluminum layer (aluminum alloy layer or pure aluminum layer) are partially peeled off, then the thick film layer side or the hard layer. The side is fixed, the force required to peel off when the other layer is pulled 180 ° opposite to the fixed side is measured, and N / 20 mm is used as a unit. In the same test, the peel strength does not change if the width of the test piece is between 10 and 30 mm.

Also, the rolled joined body for electronic equipment preferably has an elongation of 35% or more by a tensile test with a test piece width of 15 mm, and more preferably 40% or more from the viewpoint of good press workability. Elongation by a tensile test can be measured using, for example, a test piece of a tensile strength test described later, according to the measurement of elongation at break described in JIS Z 2241 or JIS Z 2201.

The rolled joined body for an electronic device preferably has a tensile strength of 3000 N or more by a tensile test with a test piece width of 15 mm, and more preferably 3500 N or more from the viewpoint of having sufficient strength and press workability. . Here, the tensile strength refers to the maximum load in the tensile test. Tensile strength can be measured according to JIS Z 2241 or JIS Z 2201 (metallic material tensile test method) using, for example, Tensilon Universal Material Testing Machine RTC-1350A (Orientec Co., Ltd.). In addition, the width of 15 mm of the test piece indicates the specification of the special test piece No. 6 in JIS Z 2201. In JIS Z 2241, for example, the specification of test piece 5 can be used. At this time, the tensile strength in the No. 6 test piece is 25 mm / 15 mm, that is, about 1.66 times, because the width of the test piece may be multiplied when converted into the tensile strength in the No. 5 test piece. Become.

The rolled joined body for an electronic device preferably has an elongation of 35% or more by a tensile test and a tensile strength of 3000 N or more by a tensile test.

In addition, the rolled joined body for electronic equipment as described above is preferable because it is excellent in workability at the time of forming into a casing, but the back and / or side surface after forming the casing is preferably rolled for electronic equipment. It is not necessary to satisfy the characteristic value of the joined body.

2. Next, the configuration of the electronic device casing according to the present invention will be described. First, FIG. 5 and FIG. 6 show a first embodiment of an electronic device casing of the present invention. FIG. 5 is a perspective view showing the first embodiment of the electronic device casing of the present invention, and FIG. 6 is a cross-sectional view in the XX ′ direction of the first embodiment of the electronic device casing of the present invention. It is a cross-sectional perspective view. The housing 5 for electronic equipment includes a back surface 50 and a side surface 51, and the back surface 50 and / or the side surface 51 includes a rolled bonded body including a stainless steel layer and an aluminum alloy layer or a pure aluminum layer. The rolled assembly for electronic equipment can be applied as it is. Therefore, from the viewpoint of improving impact resistance, the above-described conditions and ranges of the characteristic values required for the rolled joined body for electronic equipment are similarly applied to the housing for electronic equipment. However, since the casing for electronic equipment is appropriately manufactured from the above-described rolled joined body for electronic equipment through a molding process such as pressing or inner surface machining, the thickness of each layer is determined by pressing or machining. May become thin and the surface hardness may become hard.

The casing for electronic equipment of the present invention includes a rolled joined body mainly composed of metal and having a back surface and / or side surface made of a stainless steel layer and an aluminum alloy layer, or a stainless steel layer and a pure aluminum layer. As shown in FIG. 5, here, the back surface 50 refers to a surface on the opposite side to a side where a display unit (tisplay, not shown) is provided in a housing constituting an electronic device such as a smartphone. Moreover, the inner side of the housing | casing 5 for electronic devices may laminate | stack the metal material different from a rolling joined body, a plastic material, etc. In addition, when the case 5 for electronic devices includes a rolling joined body in the back surface 50, the whole or a part of the back surface 50 (for example, 2 cm x 2 cm or more, for example, 25 mm x 25 mm as shown by the plane part A of FIG. 5). It is sufficient that the flat portion of (ii) satisfies the above-mentioned characteristics described for the rolled joined body for electronic equipment. In addition, the electronic device casing 5 may have a structure including a rolled joined body on the back surface 50, but the structure is not limited to this structure depending on the structure of the electronic device, and the back surface 50 and the side surface 51 include The structure which consists of a rolling joining body may be sufficient, and the structure which contains a rolling joining body in the side surface 51 may be sufficient.

Next, a second embodiment of the electronic device casing of the present invention will be described. In the present embodiment, an electronic device casing, which is a center frame, shows an electronic device structure sandwiched between a display unit such as glass or resin and a back surface. The electronic device casing is provided on a side surface and the side surface. It is comprised from the connected internal reinforcement flame | frame (it comprises the back surface in the housing | casing for electronic devices). The housing for an electronic device can include a rolled joined body in which the side surface and / or the internal reinforcing frame is formed of a stainless steel layer and an aluminum alloy layer or a pure aluminum layer. Here, the internal reinforcement frame means a support plate that is located inside an electronic device such as a smartphone and serves as a support for improving rigidity of the entire electronic device and mounting components such as a battery and a printed board. . The internal reinforcement frame usually has holes for connection and assembly. The hole can be opened by, for example, a press. In the present embodiment, the side surface and the internal reinforcing frame can be integrally formed, but the present invention is not limited to this, and the side surface and the internal reinforcing frame may not be integrated. Moreover, you may apply a rolling joined body only to a side surface. Note that the electronic device casing of the present embodiment can be modified as appropriate according to the structure of the electronic device, similarly to the electronic device casing 5, and is limited to the structure described above. It is not something.

The rolled joined body is composed of 2 or more layers, preferably 2 to 4 layers, more preferably 2 or 3 layers, and particularly preferably 2 layers. In a preferred embodiment, in order to obtain an appearance having a metallic luster, the rolled joined body has a stainless steel layer on the outer side of the casing, and a rolled joined body composed of a stainless steel layer / aluminum alloy layer or a pure aluminum layer, or a stainless steel layer / It is a rolled joined body composed of three layers of an aluminum alloy layer or a pure aluminum layer / stainless steel layer. Further, in order to obtain an alumite appearance, an aluminum alloy layer or a pure aluminum layer is provided on the outside of the casing, and a rolled joined body composed of two layers of an aluminum alloy layer or a pure aluminum layer / stainless steel layer, or an aluminum alloy layer or a pure aluminum layer. A rolled joined body composed of three layers of / stainless steel layer / aluminum alloy layer or pure aluminum layer may be used. In the present invention, the configuration of the rolled joined body in the housing can be selected according to the use of the housing and the intended characteristics.

The stainless steel constituting the stainless steel layer is not particularly limited, and plate materials such as SUS304, SUS201, SUS316, SUS316L, SUS301, and SUS430 can be used.

Examples of the aluminum alloy include an Al—Cu alloy (2000 series), an Al—Mn alloy (3000 series), an Al—Si alloy (4000 series), and an Al—Mg alloy (5000 series) as defined in JIS. Al-Mg-Si based alloys (6000 series) and Al-Zn-Mg based alloys (7000 series) can be used. From the viewpoint of strength, corrosion resistance and impact resistance, 3000 series, 5000 series, 6000 series and 7000 series can be used. A series aluminum alloy is preferable, and a 5000 series aluminum alloy is more preferable from the viewpoint of the balance and cost. The aluminum alloy preferably contains 0.3% by mass or more of Mg.

In the present invention, the electronic device casing includes a stainless steel layer surface hardness H _S (Hv), a stainless steel layer thickness T _S (mm), an aluminum alloy layer surface hardness H _AA (Hv), or a pure aluminum layer. The surface hardness H _A (Hv) and the thickness T _AA (mm) of the aluminum alloy layer or the thickness T _A (mm) of the pure aluminum layer satisfy a specific relational expression.

The inventors of the present invention have examined elements that have a particularly large contribution to impact resistance in a rolled joined body composed of a stainless steel layer and an aluminum alloy layer or a pure aluminum layer in a casing. It has been found that it is effective to control the surface hardness and thickness of each layer so as to satisfy a specific relational expression as a parameter affecting the “deformation height” when the test is performed.
In particular, in electronic equipment housings that require increased mounting capacity due to thinning, even if the thickness of the rolled joined body is thin, for example, roll joining with excellent impact resistance even if the thickness of the back surface of the housing is 0.6 mm or less. The body layer structure was identified.

Specifically, in a casing for an electronic device having a rolled joined body composed of a stainless steel layer and an aluminum alloy layer on the back surface, the thickness T _S (mm) and the surface hardness H _S (Hv) of the stainless steel layer, and the aluminum alloy layer The thickness T _AA (mm) and the surface hardness H _AA (Hv) of the following formula (1)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 11.18 (1)
It is necessary to satisfy. By satisfying the above relational expression, it was found that the “deformation height” in the impact resistance test can be reduced to 400 μm or less, the impact resistance is high, and the housing is suitable for use.

In addition, in a casing for an electronic device having a rolled joined body composed of a stainless steel layer and a pure aluminum layer on the back surface, the thickness T _S (mm) of the stainless steel layer and the surface hardness H _S (Hv), and the thickness T of the pure aluminum layer. _A (mm) and surface hardness H _A (Hv) are expressed by the following formula (3)
H _S T _S ² + H _A T _A ² ≧ 17.93 (3)
It is necessary to satisfy. By satisfying the above relational expression, it was found that the “deformation height” in the impact resistance test can be reduced to 400 μm or less, the impact resistance is high, and the housing is suitable for use.

A surface of a stainless steel layer in a casing for an electronic device having a rolled joined body comprising a stainless steel layer and an aluminum alloy layer or a pure aluminum layer ("aluminum alloy layer" and "pure aluminum layer" are collectively referred to as "aluminum layer") The present inventors consider that the hardness, thickness, surface hardness and thickness of the aluminum layer are important parameters for impact resistance as follows. Specifically, when a rolled joined body of a stainless steel layer and an aluminum layer is used to obtain heat dissipation for the purpose of obtaining a casing for electronic equipment having a glossy appearance of stainless steel, the stainless steel layer has a certain thickness. As described above, specifically, if it is only a glossy appearance, there is no problem if it is 0.015 mm or more, but in the manufacturing process, a thickness of 0.05 mm or more is actually required from the viewpoint of handling. However, it turned out that there were the following problems if all the remainder was made into an aluminum layer. That is, in order to obtain a sufficient bonding strength between the stainless steel layer and the aluminum layer, a post-bonding process as described later is required. However, as a result of trials by the present inventors, it has been found that the impact resistance of the joined body of the conventional stainless steel layer and aluminum layer is significantly reduced because the aluminum layer is softened by heat treatment. It was. In other words, heat treatment is performed at a predetermined temperature in order to improve the bonding strength. This heat treatment temperature is a temperature at which the stainless steel layer is in an unrecrystallized temperature range and is not softened. It is the temperature range that is removed and softens. And when the hardness of the aluminum layer was too low, it was found that sufficient impact resistance could not be obtained unless the thickness of the aluminum layer was not less than a certain value, specifically 0.85 mm or more. However, if the aluminum layer is 0.85 mm or more, the total thickness of the rolled joined body is 0.9 mm or more, and the thickness of the housing becomes too thick, so that the mounting capacity inside the housing is greatly reduced. Therefore, the stainless steel layer also needs to have a certain thickness. On the other hand, the thicker the stainless steel layer, the heavier the casing. Accordingly, in order to clear such a problem, the inventors set the hardness of the aluminum layer to a certain value or more, and further increases the thickness of the aluminum layer, increases the hardness of the stainless steel layer, We found that it is necessary to take one of the following methods to increase the thickness, or to take complex measures, and by controlling each parameter, the glossy appearance of the stainless steel layer and the thinned casing for electronic devices Could get.

The ratio of the thickness T _S of the stainless steel layer to the total thickness of the rolled assembly in electronics housing, the thickness of the stainless steel layer and an aluminum layer is not particularly limited as long as it satisfies the equation (1) to (4), preferably Is from 10% to 60%, more preferably from 12% to 50%, and even more preferably from 15% to 50%. When the thickness ratio of the stainless steel layer is within this range, it is possible to obtain a housing that sufficiently secures the impact resistance of the housing and also has a sufficient heat dissipation effect by the aluminum layer. In addition, the thickness ratio of a stainless steel layer means the ratio of the sum total of the thickness of the stainless steel layer with respect to the total thickness of a rolling joining body, when two or more stainless steel layers exist in the rolling joining body in a housing | casing. Also, the thickness ratio of the aluminum layer is the sum of the thickness of the aluminum layer with respect to the total thickness of the rolled joined body, when there are two or more aluminum layers in the rolled joined body in the casing, similarly to the thickness ratio of the stainless steel layer. Say ratio.

When the total thickness of the rolled assembly in electronics housing, T S _{+ T} _AA, or is represented by T _{S +} T _A, it is not particularly limited, using the roll-bonding material on the back part of the casing or the like, electronic From the viewpoint of increasing the mounting capacity inside the device, the upper limit is usually 1.2 mm or less, preferably 1.0 mm or less, more preferably 0.8 mm or less, and even more preferably 0.7 mm or less. The lower limit is 0.2 mm or more, preferably 0.3 mm or more, more preferably 0.4 mm or more. The total thickness of the rolled joined body refers to an average value of the values obtained by obtaining an optical micrograph of the cross section of the rear surface of the housing, measuring the thickness of the rolled joined body at any 30 points in the optical micrograph. . Further, the thickness of the back surface of the housing for electronic equipment is the thickness of all layers including the rolled joined body in the back surface portion of the housing (however, 2 cm × 2 cm or more, as shown by the plane portion A in FIG. 5, for example, 25 mm × 25 mm flat portion thickness), preferably 0.2 mm or more and 1.6 mm or less. More preferably, they are 0.3 mm or more and 1.2 mm or less, More preferably, they are 0.4 mm or more and 1.0 mm or less. The thickness of the back surface of the electronic device casing is an average value of measured values obtained by measuring the thickness at any 30 points on the back surface with a micrometer.

The thickness _{T S} of the stainless steel layer, from the viewpoint of securing impact resistance during thinning is 0.05mm or 0.6mm or less. Preferably they are 0.1 mm or more and 0.5 mm or less, More preferably, they are 0.1 mm or more and 0.4 mm or less. In addition, the thickness of a stainless steel layer means the sum total of the thickness of each stainless steel layer, when the rolling joining body in a housing | casing has two or more stainless steel layers. The thickness of the stainless steel layer of the rolled joined body in the housing is obtained by obtaining an optical micrograph of the cross section of the rolled joined body, measuring the thickness of the stainless steel layer at any 10 points in the optical micrograph, and averaging the obtained values. Value.

The surface hardness H _S (Hv) of the stainless steel layer can be measured according to JIS Z 2244 (Vickers hardness test-test method) using a micro Vickers hardness meter (load 200 gf). Preferably it is 200 or more, More preferably, it is 220 or more, Most preferably, it is 230 or more. In the present invention, when the other parameters are constant, the deformation height decreases as the hardness of the stainless steel layer increases, resulting in an electronic device casing having high impact resistance. Therefore, from the viewpoint of impact resistance of the housing, H _S is preferably higher. The upper limit of the hardness of the stainless steel layer is preferably 380 or less, more preferably 340 or less, and still more preferably 330 or less. In the case where the hardness of the stainless steel layer is remarkably improved after another process after forming into the casing, there is no particular upper limit, and for example, 430 or less is preferable. Although it may be applied to the case while maintaining the hardness of the stainless steel layer in the rolled joined body before being formed into the case, a little work hardening (Hv is improved by about 10 to 30 by grinding, polishing, etc.) May be added.

The thickness _{T AA} of the aluminum alloy layer can be applied as long as usual 0.1mm or 1.1mm or less. From the viewpoint of improving the impact resistance of the housing, ensuring heat dissipation and reducing weight, it is preferably 0.12 mm to 0.9 mm, and more preferably 0.15 mm to 0.72 mm. In addition, the thickness of the aluminum alloy layer of the rolled joined body in a housing means the total thickness of each aluminum alloy layer when the rolled joined body has two or more aluminum alloy layers. The thickness of the aluminum alloy layer of the rolled joined body is a value obtained by obtaining an optical micrograph of the cross section of the rolled joined body in the housing, measuring the thickness of the aluminum alloy layer at any 10 points in the optical micrograph. The average value of

The thickness _{T A} pure aluminum layer, as well as the aluminum alloy layer, is applicable as long as usual 0.1mm or 1.1mm or less. In order to improve the impact resistance of the housing and to ensure heat dissipation and to reduce the weight, the thickness is preferably 0.12 mm or more and 0.9 mm or less, more preferably 0.15 mm or more and 0.72 mm or less. In addition, the thickness of the pure aluminum layer of the rolled joined body in a housing means the sum total of the thickness of each pure aluminum layer, when the rolled joined body has two or more pure aluminum layers. The thickness of the pure aluminum layer of the rolled joined body is a value obtained by obtaining an optical micrograph of the cross section of the rolled joined body in the housing, measuring the thickness of the pure aluminum layer at any 10 points in the optical micrograph. The average value of

3. Method of manufacturing rolled joint for electronic equipment and casing for electronic equipment The rolled joined body for electronic equipment is prepared by preparing a stainless steel plate and an aluminum alloy plate or a pure aluminum plate, and performing roll joining by the following rolling joining method. Can be manufactured. The casing for electronic equipment uses the rolled joint as the back of the casing, and is laminated with a metal material or plastic material prepared separately as necessary, and then undergoes molding processing such as pressing and machining. Can be obtained by:

When manufacturing a rolled joined body for electronic equipment by a cold joining method, after performing brush polishing etc. on the joining surface of a stainless steel plate and an aluminum alloy plate or a pure aluminum plate, they are joined together while cold rolling, Furthermore, it can manufacture by performing an annealing process. The cold rolling process may be performed in multiple stages, and temper rolling may be added after the annealing treatment. In this method, the final reduction ratio (the reduction ratio calculated from the thickness of the pre-bonding original sheet and the rolled bonded body) is 20% to 90% rolled and joined. In the case of manufacturing by the cold joining method, considering the rolling reduction, the thickness of the original plate is 0.0125 to 6 mm for the stainless steel plate, preferably 0.056 to 5 mm, more preferably 0.063 to 4 mm, and the aluminum alloy plate is 0.063 to 25 mm, preferably 0.13 to 17 mm, more preferably 0.25 to 11 mm, and a pure aluminum plate is 0.063 to 25 mm, preferably 0.13 to 17 mm, more preferably 0.25 to 11 mm. is there.

In the case of the warm joining method, it is possible to manufacture by performing brush polishing or the like on the joining surfaces in the same manner as in the cold joining method, then heating both or one of them to 200 to 500 ° C., overlapping, warm rolling and joining. it can. In this method, the final rolling reduction is about 15 to 40%. In the case of producing by a warm joining method, considering the rolling reduction, the thickness of the original plate is 0.012 to 1 mm for the stainless steel plate, preferably 0.053 to 0.83 mm, more preferably 0.059 to 0.067 mm, The aluminum alloy plate is 0.059 to 4.2 mm, preferably 0.19 to 2.8 mm, more preferably 0.24 to 1.8 mm, and the pure aluminum plate is 0.059 to 4.2 mm, preferably 0.19. It is ˜2.8 mm, more preferably 0.24 to 1.8 mm.

In the case of the vacuum surface activated bonding method (hereinafter, the surface activated bonding method is also synonymous), the step of sputter etching the bonding surface of the stainless steel plate and the aluminum alloy plate or the pure aluminum plate, By a method including a step of joining by pressure welding so that light reduction with a rolling reduction of 0% to 25% and a step of performing batch heat treatment at 200 ° C. to 400 ° C. or continuous heat treatment at 300 ° C. to 890 ° C. Can be manufactured. In this manufacturing method, the number of layers of the obtained rolled joined body can be changed according to the number of times the sputter etching treatment step and the joining step are performed. For example, a rolled joined body composed of two layers has a sputter etching treatment step. And a combination of bonding steps once, and then heat treatment can be performed, and the three-layer rolled joined body is subjected to heat treatment after repeating the combination of the sputter etching treatment step and the bonding step twice. It can be manufactured by doing.

As described above, the joining method for obtaining a rolled joined body for electronic equipment is not limited, but if the hardness of stainless steel becomes too high, the toughness is lowered, and the stainless steel is liable to be cracked. In a joined body with stainless steel, it is difficult to soften and anneal stainless steel during annealing after joining. Therefore, the final rolling reduction is preferably 40% or less in any joining method. More preferably, it is 30% or less, More preferably, it is 25% or less. In particular, when the rolling reduction rate is too high, remarkable work hardening occurs and the toughness decreases, so there is a risk of cracking in the stainless steel layer during rolling joining, handling, or use as a housing. The rolling reduction of the layer is preferably 35% or less. Hereinafter, a method for manufacturing surface activated bonding that is easy to bond even when the rolling reduction is low will be described.

The thickness of the stainless steel plate before joining is usually applicable as long as it is 0.045 mm or more, and the lower limit is preferably from the viewpoint of impact resistance when handling the rolled joint and having a certain thickness of stainless steel. Moreover, after making it into a housing | casing, it is 0.06 mm or more from a viewpoint of ensuring the grinding | polishing allowance at the time of decoration and mirror surface processing, More preferably, it is 0.1 mm or more. The upper limit is not particularly limited because the higher the stainless steel ratio, the higher the impact resistance. However, since the stainless steel becomes heavier when the thickness of the stainless steel becomes too thick, it is preferably 0.6 mm from the viewpoint of reducing the weight when used as a housing. Hereinafter, it is more preferably 0.5 mm or less, and still more preferably 0.4 mm or less. The thickness of the stainless steel plate before joining can be measured with a micrometer or the like, and means an average value of thicknesses measured at 10 points randomly selected from the surface of the stainless steel plate.

The surface hardness (Hv) of the stainless steel plate before joining is preferably 160 or more, more preferably 180 or more. In the present invention, the hardness of the stainless steel layer in the rolled joined body affects the impact resistance, but as described above, it is considered that the effect of hardening of the stainless steel due to the state immediately before joining and the strain entering at the time of joining is large. It is preferable to control the hardness of the stainless steel plate to some extent. Therefore, the surface (Hv) of the stainless steel layer is preferably 350 or less, more preferably 330 or less.

The thickness of the aluminum alloy plate before joining is usually applicable if it is 0.05 mm or more, and the lower limit is preferably 0.1 mm or more, more preferably 0.2 mm or more. The upper limit is usually 3.3 mm or less, preferably 1.5 mm or less, more preferably 1.0 mm or less from the viewpoint of weight reduction and cost. The thickness of the aluminum alloy plate before joining can be determined in the same manner as the stainless steel plate.

The thickness of the pure aluminum plate before joining is usually 0.05 mm or more, and the lower limit is preferably 0.1 mm or more, more preferably 0.2 mm or more. The upper limit is usually 3.3 mm or less, preferably 2.2 mm or less, more preferably 1.5 mm or less from the viewpoint of weight reduction and cost. The thickness of the pure aluminum plate before joining can be determined in the same manner as the stainless steel plate.

In the sputter etching process, the joining surface of the stainless steel plate and the joining surface of the aluminum alloy plate or the pure aluminum surface are each sputter etched.

Specifically, the sputter etching process is performed by preparing a stainless steel plate and an aluminum alloy plate or a pure aluminum plate as a long coil having a width of 100 mm to 600 mm. The area of the electrode exposed to the plasma generated by the glow discharge is determined by applying an alternating current of 1 MHz to 50 MHz between the grounded one electrode and the other insulated and supported electrode. It is performed as 1/3 or less of the area of the other electrode. During the sputter etching process, the grounded electrode is in the form of a cooling roll to prevent the temperature of each conveying material from rising.

In the sputter etching process, the adsorbed material on the surface is completely removed by sputtering the surface where the stainless steel plate and the aluminum alloy plate or pure aluminum plate are joined with an inert gas in a vacuum, and part of the oxide film on the surface Or remove all. The oxide film does not necessarily need to be completely removed, and a sufficient bonding force can be obtained even if it remains partially. By leaving a part of the oxide film, the sputter etching processing time can be significantly reduced as compared with the case where the oxide film is completely removed, and the productivity of the housing can be improved. As the inert gas, argon, neon, xenon, krypton, or a mixed gas containing at least one of these can be used. For both the stainless steel plate, the aluminum alloy plate, and the pure aluminum plate, the adsorbed material on the surface can be completely removed with an etching amount of about 1 nm (in terms of SiO ₂ ).

For example, in the case of a single plate, the sputter etching process for a stainless steel plate can be performed under vacuum, for example, with a plasma output of 100 W to 1 KW for 1 to 50 minutes, and for a long material such as a line material, for example. Under vacuum, for example, it can be performed at a plasma output of 100 W to 10 KW and a line speed of 1 m / min to 30 m / min. The degree of vacuum at this time is preferably higher in order to prevent re-adsorbed substances on the surface, but may be, for example, 1 × 10 ⁻⁵ Pa to 10 Pa. In the sputter etching process, the temperature of the stainless steel plate is preferably maintained at room temperature to 150 ° C. from the viewpoint of preventing softening of the aluminum alloy plate.

The stainless steel plate with a part of the oxide film remaining on the surface can be obtained by setting the etching amount of the stainless steel plate to 1 nm to 10 nm, for example. If necessary, the etching amount may exceed 10 nm.

For example, in the case of a single plate, the sputter etching process for an aluminum alloy plate can be performed under a vacuum, for example, with a plasma output of 100 W to 1 KW for 1 to 50 minutes, or for a long material such as a line material. In this case, it can be performed at a plasma output of 100 W to 10 KW and a line speed of 1 m / min to 30 m / min. The degree of vacuum at this time is preferably higher in order to prevent re-adsorbed substances on the surface, but may be 1 × 10 ⁻⁵ Pa to 10 Pa.

The aluminum alloy plate in which a part of the oxide film on the surface remains can be obtained by setting the etching amount of the aluminum alloy plate to 1 nm to 10 nm, for example. If necessary, the etching amount may exceed 10 nm.

For example, in the case of a single plate, the sputter etching process for a pure aluminum plate can be performed under a vacuum, for example, with a plasma output of 100 W to 1 KW for 1 to 50 minutes, and for example, a long material such as a line material is used. In this case, it can be performed at a plasma output of 100 W to 10 KW and a line speed of 1 m / min to 30 m / min. The degree of vacuum at this time is preferably higher in order to prevent re-adsorbed substances on the surface, but may be 1 × 10 ⁻⁵ Pa to 10 Pa.

A pure aluminum plate in which a part of the oxide film on the surface remains can be obtained by setting the etching amount of the pure aluminum plate to, for example, 1 nm to 10 nm. If necessary, the etching amount may exceed 10 nm.

The joining surface of the stainless plate and aluminum alloy plate or pure aluminum plate sputter-etched as described above is light rolled so that the rolling reduction of the stainless steel layer is 0% to 25%, preferably 0% to 15%. For example, a stainless steel plate and an aluminum alloy plate or a pure aluminum plate are joined by pressure welding by roll pressure welding.

The reduction ratio of the stainless steel layer is obtained from the thickness of the stainless steel plate before joining and the thickness of the stainless steel layer of the final rolled joined body. That is, the rolling reduction ratio of the stainless steel layer is obtained by the following formula: (thickness of stainless steel plate before joining-thickness of stainless steel layer of final rolled joined body) / thickness of stainless steel plate of material before joining. .

In joining a stainless steel layer to an aluminum alloy layer or a pure aluminum layer, the aluminum alloy layer or the pure aluminum layer is often more easily deformed, and the reduction rate of the stainless steel layer is lower than the reduction rate of the aluminum alloy layer or the pure aluminum layer. Lower. Since the stainless steel layer tends to cause work hardening when the rolling reduction is high, it is preferably 15% or less, more preferably 10% or less, and further preferably 8% or less. In addition, since the thickness does not need to change before and after pressing, the lower limit value of the rolling reduction is 0%. However, when the hardness of the stainless steel plate is low, impact resistance can be improved by intentionally hardening the work. Is possible. In this case, it is preferably 0.5% or more, more preferably 2% or more, and further preferably 3% or more. The reduction ratio of the stainless steel layer is preferably 0 to 15%, particularly preferably 0.5 to 10% from the viewpoint of achieving both impact resistance and suppression of work hardening. Further, in the surface activated bonding method, it can be made 10% or less in particular, and it becomes possible to further suppress the hardening of the stainless steel.

In the present invention, the rolling reduction of the aluminum alloy layer is not particularly limited, but is preferably 5% or more, more preferably 6% or more, and more preferably 8% or more in order to ensure the bonding strength before the diffusion heat treatment. . The rolling reduction of the aluminum alloy layer is determined from the thickness of the aluminum alloy plate before joining and the thickness of the aluminum alloy layer of the final rolled joined body. That is, the reduction ratio of the aluminum alloy layer is expressed by the following formula: (the thickness of the aluminum alloy plate of the material before joining−the thickness of the aluminum alloy layer of the final rolled joined body) / the thickness of the aluminum alloy plate of the material before joining. , Is required.

The upper limit of the reduction ratio of the aluminum alloy layer is not particularly limited, and is not limited to, for example, the surface activated bonding method, but is 70% or less, preferably 50% or less, and more preferably 40% or less. When the upper limit of the rolling reduction of the aluminum alloy layer is within this range, it is easy to ensure the bonding force while maintaining the thickness accuracy. Further, in the surface activated bonding method, it can be particularly 18% or less, and the flatness of the aluminum alloy layer can be further maintained.

In the present invention, the reduction rate of the pure aluminum layer is not particularly limited, but is preferably 5% or more, more preferably 10% or more, and more preferably 12% or more in order to ensure the bonding strength before the diffusion heat treatment. . The reduction rate of the pure aluminum layer is determined from the thickness of the pure aluminum plate before joining and the thickness of the pure aluminum layer of the final rolled joined body. That is, the reduction ratio of the pure aluminum layer is expressed by the following formula: (thickness of pure aluminum plate of material before joining−thickness of pure aluminum layer of final rolled joined body) / thickness of pure aluminum plate of material before joining , Is required.

The upper limit of the reduction rate of the pure aluminum layer is not particularly limited, and is not limited to, for example, the surface activated bonding method, but is 70% or less, preferably 50% or less, and more preferably 40% or less. When the upper limit of the reduction ratio of the pure aluminum layer is within this range, it is easy to ensure the bonding force while maintaining the thickness accuracy. Further, in the surface activated bonding method, it can be particularly 18% or less, and the flatness of the pure aluminum layer can be further maintained.

The rolling reduction of the rolled joined body is preferably 40% or less, more preferably 15% or less, and still more preferably 14% or less in the case of the surface activated joining method. The lower limit is not particularly limited, but is preferably 4% or more, more preferably 5% or more, still more preferably 6% or more, and particularly preferably 7.5% or more from the viewpoint of bonding strength. In the surface activated bonding method, the upper limit can be made 15% or less and the lower limit can be made 4% or more, and it is easy to obtain characteristics more stably. The rolling reduction of the rolled joined body is determined from the total thickness of the stainless steel plate and aluminum alloy plate or pure aluminum plate of the material before joining and the final thickness of the rolled joined body. That is, the rolling reduction of the rolled joined body is expressed by the following formula: (total thickness of stainless steel plate and aluminum alloy plate or pure aluminum plate of material before joining−final thickness of rolled joined body) / stainless steel of material before joining The total thickness of the plate and the aluminum alloy plate or pure aluminum plate is determined.

The rolling line load of roll pressure welding is not particularly limited, and is set so as to achieve a predetermined rolling reduction of the rolled joined body. For example, in the case of surface activated joining, 1.6 tf / cm to 10.0 tf / cm. Can be set in the range. For example, when the roll diameter of the pressure welding roll is 100 mm to 250 mm, the rolling line load of the roll pressure welding is preferably 1.9 tf / cm to 4.0 tf / cm, more preferably 2.3 tf / cm to 3.0 tf / cm. cm. However, when the roll diameter is increased, or when the stainless steel plate, aluminum alloy plate or pure aluminum plate before joining is thick, the rolling line load is applied to secure the pressure in order to achieve the specified reduction ratio. It may be necessary to increase the value, and the present invention is not limited to this numerical range.

The temperature at the time of bonding is not particularly limited, and is, for example, from room temperature to 150 ° C. in the case of surface activated bonding.

In the case of surface activated bonding, the bonding is performed in a non-oxidizing atmosphere, for example, Ar or the like, in order to prevent the bonding strength between the stainless steel plate and the aluminum alloy plate or pure aluminum plate from being reduced by re-adsorption of oxygen It is preferable to carry out in an inert gas atmosphere.

The rolled bonded body obtained by bonding the stainless steel plate and the aluminum alloy plate or the pure aluminum plate as described above is subjected to heat treatment. By heat treatment, the adhesion between the layers can be increased and sufficient bonding strength can be obtained.

In the case of batch heat treatment, for example, the heat treatment temperature is 200 ° C. to 400 ° C., preferably 200 ° C. to 370 ° C., more preferably 250 ° C. to 345 ° C. For example, in the case of continuous heat treatment, the temperature is 300 to 890 ° C., preferably 300 to 800 ° C., and more preferably 350 to 550 ° C. At this heat treatment temperature, stainless steel is in an unrecrystallized temperature range and is not softened substantially, and aluminum alloy and pure aluminum are in a temperature range in which processing strain is removed and softened. The heat treatment temperature refers to the temperature of the rolled joined body that undergoes the heat treatment.

In this heat treatment, at least a metal element (for example, Fe, Cr, Ni) contained in the stainless steel is thermally diffused into the aluminum alloy layer or the pure aluminum layer. Further, a metal element contained in stainless steel and aluminum may be thermally diffused with each other.

The heat treatment time can be appropriately set according to the heat treatment method (batch heat treatment or continuous heat treatment), the heat treatment temperature and the size of the rolled joined body to be heat treated. For example, in the case of batch heat treatment, the rolling joined body is kept soaked for 0.5 to 10 hours, preferably 2 to 8 hours after the temperature of the rolled joined body reaches a predetermined temperature. If no intermetallic compound is formed, there is no problem even if batch heat treatment is performed for 10 hours or more. In the case of continuous heat treatment, the rolled joined body is kept soaked for 20 seconds to 5 minutes after the temperature of the rolled joined body reaches a predetermined temperature. The heat treatment time refers to the time after the rolled joined body to be heat treated reaches a predetermined temperature, and does not include the temperature rise time of the rolled joined body. For heat treatment time, for example, for materials as small as A4 size (paper size), about 1 to 2 hours is sufficient for batch heat treatment, but long materials such as coil materials with a width of 100 mm or more and a length of 10 m or more are large. As for materials, batch heat treatment requires about 2 to 8 hours. Through the above steps, the rolled joined body for electronic equipment according to the present invention can be manufactured.

As a means for controlling the surface hardness of the aluminum alloy layer or pure aluminum layer of the rolled joined body for electronic equipment to satisfy a predetermined relational expression, for example, the aluminum alloy layer with respect to the target thickness of the rolled joined body Alternatively, there is a method in which after a rolled joined body having a thick pure aluminum layer is once produced, the aluminum alloy layer or the pure aluminum layer of the rolled joined body is ground to reduce the thickness and finish to a target thickness. By grinding the aluminum alloy layer or the pure aluminum layer, the aluminum alloy layer or the pure aluminum layer is cured and the hardness can be improved. In addition, the shape of the rolled joined body obtained by joining and heat treatment may be corrected by a tension leveler so that the elongation percentage is about 1 to 2%. By this shape modification, the thickness can be reduced by about 1 to 2%, the aluminum alloy layer or the pure aluminum layer can be cured, and the surface hardness can be improved. These means may be appropriately combined. For example, after the shape correction by the tension leveler is performed, the aluminum alloy layer or the pure aluminum layer can be ground.

Further, as a means for increasing the surface hardness of the stainless steel layer of the rolled joined body for electronic equipment and controlling it so as to satisfy a predetermined relational expression, for example, a raw material having a high surface hardness (the tempering symbol H in descending order of hardness) > 3 / 4H> 1 / 2H> BA) and joining them to produce a rolled joined body. However, it should be noted that if the surface hardness of the stainless steel layer is too high, it becomes difficult to process the housing. Or you may raise the surface hardness of the stainless steel layer of the rolling joined body after joining by making the load at the time of rolling joining high. For example, by joining so that the reduction ratio of the stainless steel layer is 0.5 to 10%, the surface hardness of the stainless steel layer is increased from 160 to 200 (Hv) to about 270 (Hv), and the impact resistance is improved. Can be made.

The manufactured rolled joined body for electronic equipment can be used as the back surface of a casing for electronic equipment through a molding process such as pressing or cutting of the inner surface. In addition, it can be widely used as a rolled joined body used for electronic equipment such as an internal reinforcing member by utilizing its thin thickness and high impact resistance.

Hereinafter, the present invention will be described in more detail based on examples and comparative examples, but the present invention is not limited to these examples.

1. Example 1 Rolled bonded body for electronic equipment comprising a stainless steel layer / aluminum alloy layer (Example 1)
The following types of materials were prepared as original plates, and a rolled bonded body for electronic equipment was manufactured by a surface activated bonding method.
SUS304 BA (thickness 0.25 mm) was used as the stainless steel material, and aluminum alloy A5052 H34 (thickness 0.8 mm) was used as the aluminum alloy material.
Sputter etching processing was performed on each surface where SUS304 and A5052 were bonded. Sputter etching for SUS304 was conducted with Ar as a sputter gas, under conditions of 0.1 Pa, plasma output of 4800 W, line speed of 4 m / min, and sputter etching for A5052 with Ar as a sputter gas. The test was performed under the conditions of plasma output 6400 W and line speed 4 m / min under 0.1 Pa.
SUS304 and A5052 after the sputter etching treatment were joined by roll pressure welding at a room temperature at a rolling line load of 3.0 tf / cm to 6.0 tf / cm to obtain a rolled joined body of SUS304 and A5052. This rolled joined body was subjected to batch heat treatment at 320 ° C. for 8 hours.
Subsequently, the rolled joint was subjected to shape correction with an elongation of about 1 to 2% using a tension leveler. As a result, the total thickness of the rolled joined body was reduced by about 1 to 2%, and the aluminum alloy layer was hardened. Thereafter, the A5052 surface of the rolled joined body was ground using emery paper to produce a rolled joined body for electronic equipment such that the total thickness of the rolled joined body was 0.561 mm.

(Example 2)
The following types of materials were prepared as original plates, and a rolled bonded body for electronic equipment was manufactured by a surface activated bonding method.
SUS304 BA (thickness 0.05 mm) was used as the stainless steel material, and aluminum alloy A5052 H34 (thickness 0.8 mm) was used as the aluminum alloy material.
Sputter etching processing was performed on each surface where SUS304 and A5052 were bonded. Sputter etching for SUS304 was performed under conditions of 0.3 Pa under a plasma output of 700 W and 12 minutes under Ar, and sputter etching for A5052 was performed with Ar as a sputter gas. It was carried out under conditions of plasma output 700 W and 12 minutes under 3 Pa.
SUS304 and A5052 after sputter etching were processed at a normal temperature, with a rolling roll diameter of 100 mm to 250 mm, a rolling line load of 0.5 tf / cm to 5.0 tf / cm, and a reduction rate of 0 to 5% of the stainless steel layer. Joined by roll pressure welding, a rolled joined body of SUS304 and A5052 was obtained. This rolled joined body was subjected to batch heat treatment at 300 ° C. for 1 hour to produce a rolled joined body for electronic equipment having a total thickness of 0.800 mm.

(Example 3)
SUS304 BA (thickness 0.15 mm) was used as the stainless steel material, aluminum alloy A5052 H34 (thickness 0.5 mm) was used as the aluminum alloy material, and the rolled joined body was cut to a total thickness of 0.457 mm. Produced a rolled joined body for electronic equipment in the same manner as in Example 1 above.

Example 4
SUS316L BA (thickness 0.1 mm) is used as a stainless steel material, aluminum alloy A5052 H34 (thickness 0.5 mm) is used as an aluminum alloy material, and shape modification by a tension leveler and grinding of an aluminum alloy layer are not performed. In the same manner as in Example 1, a rolled joined body for electronic equipment having a total thickness of 0.579 mm was manufactured.

(Example 5)
Similar to Example 1 except that SUS316L BA (thickness 0.1 mm) is used as the stainless steel material, aluminum alloy A5052 H34 (thickness 0.5 mm) is used as the aluminum alloy material, and the aluminum alloy layer is not ground. Thus, a rolled joined body for electronic equipment having a total thickness of 0.579 mm was manufactured.

(Example 6)
An electronic device having a total thickness of 0.552 mm as in Example 2 above, except that SUS304 BA (thickness 0.2 mm) was used as the stainless steel material and aluminum alloy A5052 H34 (thickness 0.4 mm) was used as the aluminum alloy material. Rolled joints were produced.

(Example 7)
Similar to Example 1 except that SUS304 BA (thickness 0.15 mm) is used as the stainless steel material, aluminum alloy A5052 H34 (thickness 0.5 mm) is used as the aluminum alloy material, and the aluminum alloy layer is not ground. Thus, a rolled joined body for electronic equipment having a total thickness of 0.595 mm was manufactured.

(Example 8)
SUS304 3 / 4H (thickness 0.15 mm) is used as the stainless steel material, and aluminum alloy A5052 H34 (thickness 0.47 mm) is used as the aluminum alloy material. A rolled joint was produced.

Example 9
SUS304 H (thickness 0.2 mm) was used as the stainless steel material, and aluminum alloy A5052 H34 (thickness 0.25 mm) was used as the aluminum alloy material. Rolling joining for electronic equipment having a total thickness of 0.403 mm was performed in the same manner as in Example 1 above. The body was manufactured.

(Example 10)
SUS304 1 / 2H (thickness 0.25 mm) is used as the stainless steel material, and roll joining for electronic equipment is performed in the same manner as in Example 1 except that the rolled joint is cut to a total thickness of 0.601 mm. The body was manufactured.

(Example 11)
A rolled joined body for electronic equipment having a total thickness of 0.801 mm was manufactured in the same manner as in Example 2 except that SUS316L 1 / 2H (thickness 0.05 mm) was used as the stainless steel material.

(Example 12)
A rolled joined body for electronic equipment having a total thickness of 0.798 mm was manufactured in the same manner as in Example 2 except that SUS304 1 / 2H (thickness 0.1 mm) was used as the stainless steel material.

(Example 13)
A rolled joined body for electronic equipment having a total thickness of 0.803 mm was manufactured in the same manner as in Example 2 except that SUS304 BA (thickness: 0.1 mm) was used as the stainless steel material.

(Example 14)
A rolled joined body for electronic equipment having a total thickness of 0.952 mm was manufactured in the same manner as in Example 2 except that SUS304 BA (thickness 0.2 mm) was used as the stainless steel material.

(Example 15)
A rolled joined body for electronic equipment having a total thickness of 0.907 mm was manufactured in the same manner as in Example 2 except that SUS304 1 / 2H (thickness 0.2 mm) was used as the stainless steel material.

(Example 16)
A rolled bonded body for electronic equipment having a total thickness of 0.970 mm was manufactured in the same manner as in Example 1 except that the aluminum alloy layer was not ground.

(Example 17)
Rolling for electronic equipment having a total thickness of 0.768 mm as in Example 2 above, except that SUS304 BA (thickness 0.5 mm) was used as the stainless steel material and A5052 H34 (thickness 0.3 mm) was used as the aluminum alloy material. A joined body was produced.

(Example 18)
A rolled joined body for electronic equipment having a total thickness of 0.984 mm was manufactured in the same manner as in Example 1 except that SUS304 1 / 2H (thickness: 0.25 mm) was used as the stainless steel material and the aluminum alloy layer was not ground. .

(Comparative Example 1)
Rolling for electronic equipment having a total thickness of 0.400 mm as in Example 2 above, except that SUS304 BA (thickness 0.1 mm) was used as the stainless steel material and A5052 H34 (thickness 0.3 mm) was used as the aluminum alloy material. A joined body was produced.

(Comparative Example 2)
Rolling for electronic equipment having a total thickness of 0.363 mm in the same manner as in Example 1 except that SUS304 BA (thickness 0.15 mm) was used as the stainless steel material and A5052 H34 (thickness 0.5 mm) was used as the aluminum alloy material. A joined body was produced.

[Thickness of stainless steel layer / aluminum alloy layer]
Obtaining optical micrographs of cross sections of the rolled joined bodies obtained in Examples 1 to 18 and Comparative Examples 1 and 2, and measuring the thickness of the stainless steel layer and the aluminum alloy layer at any 10 points in the optical micrographs, The average value of the obtained values was calculated.

[Thickness of rolled joint (total thickness)]
The thickness at arbitrary 30 points on the rolled joined body was measured with a micrometer, and the average value of the obtained measured values was calculated.

[surface hardness]
Using a micro Vickers hardness meter (load 200 gf), the surface hardness (Hv) of the stainless steel layer was measured according to JIS Z 2244 (Vickers hardness test-test method). Further, the surface hardness (Hv) of the aluminum alloy layer was measured according to JIS Z 2244 (Vickers hardness test-test method) using a micro Vickers hardness meter (load 50 gf).

[Measurement of deformation height]
A weight was dropped from a predetermined height onto the steel balls fixed on the rolled joined bodies obtained in Examples 1 to 18 and Comparative Examples 1 to 2, and the impact resistance was evaluated from the deformation amount of the rolled joined bodies. . Specifically, as shown in FIG. 1, a rolled joined body 1 (size: 25 mm × 25 mm) to be measured is placed on a donut-shaped plastic base 10 (outer diameter 17 mm, inner diameter 10 mm, height 5 mm). The aluminum alloy layer was placed on the lower side. A steel ball 20 (SUJ2, 6 mm in diameter) was placed on the rolled joined body 1, and a 20 g weight 40 was dropped along the acrylic tube 30 from a height of L = 500 mm. Then, as shown in FIG. 2, the aluminum alloy layer 2 is on the upper side and the stainless steel layer 3 is on the lower side, and the thickness of the rolled joint before and after the drop test is measured with a digital gauge (DG-205 manufactured by PEACOCK). The difference d (μm) was used as an index of impact resistance as the deformation height.

[Evaluation results]
H _S T _S ² determined based on the thickness and surface hardness of the stainless steel layer and aluminum alloy layer, the total thickness of the rolled joint, and the values measured for the rolled joints of Examples 1 to 18 and Comparative Examples 1 and ² , H _AA T _AA ² , H _S T _S ² + H _AA T _AA ² are summarized in Table 1. The measured deformation height (μm) is also shown in Table 1. Further, FIG. 3 shows the relationship between H _S T _S ² + H _AA T _AA ² and deformation height (μm) for the rolled joined bodies of Examples 1 to 18 and Comparative Examples 1 and 2.

[Evaluation results]
From the results of Table 1 and FIG. 3, the rolled joined body composed of the stainless steel layer and the aluminum alloy layer is expressed by the following formula (1).
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 11.18 (1)
It was found that the deformation height can be suppressed to 400 μm or less by satisfying the above. A deformation height of 400 μm or less can be evaluated as a range that does not adversely affect the components mounted inside the casing when the rolled joined body is used as the casing of the electronic device.
Moreover, following formula (2)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 14.72 (2)
By satisfying the above, it has been found that the deformation height is further reduced and can be suppressed to 340 μm or less. The deformation height of 340 μm or less is a range that does not adversely affect the components mounted inside the case when the rolled joined body is used as the case of the electronic device. Increase in battery capacity, increase in mounting capacity, and the like can be achieved.

2. Rolled joined body for electronic equipment comprising a stainless steel layer / pure aluminum layer (Example 19)
The following types of materials were prepared as original plates, and a rolled bonded body for electronic equipment was manufactured by a surface activated bonding method.
SUS304 3 / 4H (thickness 0.2 mm) was used as the stainless steel material, and pure aluminum A1050 H18 (thickness 0.85 mm) was used as the pure aluminum alloy material.
Sputter etching was performed on each surface where SUS304 and A1050 were bonded. The sputter etching for SUS304 was performed under conditions of 0.3 Pa under a plasma output of 700 W and 12 minutes under Ar, and the sputter etching for A1050 was performed by flowing Ar as a sputter gas. It was carried out under conditions of plasma output 700 W and 12 minutes under 3 Pa.
SUS304 and A1050 after the sputter etching treatment are performed at room temperature at a rolling roll diameter of 100 mm to 250 mm, a rolling line load of 0.5 tf / cm to 5.0 tf / cm, and a reduction rate of 0 to 5% of the stainless steel layer. Joined by roll pressure welding, a rolled joined body of SUS304 and A1050 was obtained. This rolled joined body was subjected to batch heat treatment at 300 ° C. for 1 hour to produce a rolled joined body for electronic equipment having a total thickness of 0.883 mm.

(Example 20)
The following types of materials were prepared as original plates, and a rolled bonded body for electronic equipment was manufactured by a surface activated bonding method.
SUS304 BA (thickness 0.25 mm) was used as the stainless steel material, and pure aluminum A1050 H18 (thickness 0.85 mm) was used as the pure aluminum material.
Sputter etching was performed on each surface where SUS304 and A1050 were bonded. Sputter etching for SUS304 is performed with Ar flowing as a sputter gas under conditions of plasma output of 4800 W and a line speed of 4 m / min under 0.1 Pa. Sputter etching for A1050 is performed with Ar flowing as a sputter gas. The test was performed under the conditions of plasma output 6400 W and line speed 4 m / min under 0.1 Pa.
SUS304 and A1050 after the sputter etching treatment were joined by roll pressure welding at a room temperature at a rolling line load of 3.0 tf / cm to 6.0 tf / cm to obtain a rolled joined body of SUS304 and A1050. This rolled joined body was subjected to batch heat treatment at 300 ° C. for 8 hours.
Subsequently, the rolled joint was subjected to shape correction with an elongation of about 1 to 2% using a tension leveler. As a result, the total thickness of the rolled joined body was reduced by about 1 to 2%, the aluminum alloy layer was cured, and a rolled joined body for electronic equipment having a total thickness of 0.995 mm was manufactured.

(Example 21)
A rolled joined body for electronic equipment having a total thickness of 0.988 mm was manufactured in the same manner as in Example 20 except that SUS316L BA (thickness: 0.25 mm) was used as the stainless steel material.

(Example 22)
A total thickness of 1.01 mm was obtained in the same manner as in Example 20 except that SUS304 1 / 2H (thickness 0.27 mm) was used as the stainless steel material and pure aluminum A1100 H18 (thickness 0.85 mm) was used as the pure aluminum material. A rolled joined body for electronic equipment was manufactured.

(Example 23)
A rolled joined body for electronic equipment having a total thickness of 1.012 mm was manufactured in the same manner as in Example 19 except that SUS304 3 / 4H (thickness 0.3 mm) was used as the stainless steel material.

(Comparative Example 3)
An electronic device having a total thickness of 0.550 mm as in Example 19 except that SUS304 BA (thickness 0.2 mm) was used as the stainless steel material and pure aluminum A1050 H34 (thickness 0.4 mm) was used as the pure aluminum material. Rolled joints were produced.

[Measurement of thickness of stainless steel layer / pure aluminum layer]
The rolled joints obtained in Examples 19 to 23 and Comparative Example 3 were rolled joints for electronic equipment comprising the above-mentioned stainless steel layer / aluminum alloy layer, except that the description was applied by replacing the aluminum alloy layer with a pure aluminum layer. In the same manner as the body measuring method, the thickness of the stainless steel layer and the pure aluminum layer, the total thickness of the rolled joined body, the surface hardness of the stainless steel layer and the pure aluminum layer, and the deformation height as an index of impact resistance were measured. The results are summarized in Table 2. Further, FIG. 4 shows the relationship between H _S T _S ² + H _A T _A ² and deformation height (μm) for the rolled joined bodies of Examples 19 to 23 and Comparative Example 3.

[Evaluation results]
From the results shown in Table 2 and FIG. 4, for the rolled joined body composed of the stainless steel layer and the pure aluminum layer, the following formula (3)
H _S T _S ² + H _A T _A ² ≧ 17.93 (3)
It was found that the deformation height can be suppressed to 400 μm or less by satisfying the above. A deformation height of 400 μm or less is evaluated as a range that does not adversely affect the components mounted inside the casing when the rolled joined body is used as the casing of the electronic device.
Moreover, following formula (4)
H _S T _S ² + H _A T _A ² ≧ 22.52 (4)
By satisfying the above, it became clear that the deformation height is further reduced and can be suppressed to 340 μm or less. The deformation height of 340 μm or less is a range that does not adversely affect the components mounted inside the case when the rolled joined body is used as the case of the electronic device. Increase in battery capacity, increase in mounting capacity, and the like can be achieved.

3. Example 24 for an electronic device molded from a rolled joined body made of a stainless steel layer / aluminum alloy layer (Example 24)
First, the following types of materials were prepared as original plates, and a rolled joined body was manufactured by a surface activated joining method.
SUS304 BA (thickness 0.25 mm) was used as the stainless steel material, and aluminum alloy A5052 H34 (thickness 0.8 mm) was used as the aluminum alloy material.
Sputter etching processing was performed on each surface where SUS304 and A5052 were bonded. Sputter etching for SUS304 was conducted with Ar as a sputter gas, under conditions of 0.1 Pa, plasma output of 4800 W, line speed of 4 m / min, and sputter etching for A5052 with Ar as a sputter gas. The test was performed under the conditions of plasma output 6400 W and line speed 4 m / min under 0.1 Pa.
SUS304 and A5052 after the sputter etching treatment were joined by roll pressure welding at a room temperature at a rolling line load of 3.0 tf / cm to 6.0 tf / cm to obtain a rolled joined body of SUS304 and A5052. This rolled joined body was subjected to batch heat treatment at 320 ° C. for 8 hours.
Subsequently, the rolled joint was subjected to shape correction with an elongation of about 1 to 2% using a tension leveler. As a result, the total thickness of the rolled joined body was reduced by about 1 to 2%, and the aluminum alloy layer was cured to produce a rolled joined body having a total thickness of 0.970 mm.

Subsequently, the obtained rolled joined body was deep drawn at a length of 150 mm × width of 75 mm and a depth of 10 mm. Next, the stainless steel layer was polished, and the aluminum alloy layer was ground to produce a casing having a total thickness of 0.551 mm to be the back surface of the electronic device.

[Measurement of thickness of stainless steel layer / pure aluminum layer]
After the central portion of the rear surface of the obtained casing is cut out to a size of 25 mm × 25 mm, the stainless steel layer and the aluminum alloy layer are measured in the same manner as the measurement method of the rolled joined body for electronic equipment composed of the above stainless steel layer / aluminum alloy layer. , The surface hardness of the stainless steel layer and the aluminum alloy layer, and the deformation height as an index of impact resistance were measured. The results are summarized in Table 3.

[Evaluation results]
As shown in Table 3, the electronic device casing of Example 24 obtained by forming a rolled joined body made of a stainless steel layer and an aluminum alloy layer has the following formula (1) or formula (2).
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 11.18 (1)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 14.72 (2)
It was found that the deformation height can be suppressed to 258 μm. This impact resistance is a range that does not adversely affect the parts mounted inside the housing when used as the back of the housing of the electronic device, making the entire electronic device thinner, increasing the battery capacity, It is possible to increase the mounting capacity.

4). Rolled joined body for electronic equipment comprising aluminum alloy layer / stainless steel layer / aluminum alloy layer (Example 25)
The following types of materials were prepared as original plates, and a rolled bonded body for electronic equipment was manufactured by a surface activated bonding method.
SUS304 BA (thickness 0.3 mm) was used as the stainless steel material, and aluminum alloy A5052 H34 (thickness 0.16 mm) was used as the aluminum alloy material.
Sputter etching processing was performed on each surface where SUS304 and A5052 were bonded. Sputter etching for SUS304 was performed under conditions of 0.3 Pa under a plasma output of 700 W and 12 minutes under Ar, and sputter etching for A5052 was performed with Ar as a sputter gas. It was carried out under conditions of plasma output 700 W and 12 minutes under 3 Pa.
SUS304 and A5052 after sputter etching were processed at a normal temperature, with a rolling roll diameter of 100 mm to 250 mm, a rolling line load of 0.5 tf / cm to 5.0 tf / cm, and a reduction rate of 0 to 5% of the stainless steel layer. Bonding was performed by roll pressure welding to obtain a two-layer rolled bonded body composed of SUS304 and A5052.
Next, a sputter etching process was performed on the surface of SUS304 of the two-layer rolling joined body and the surface of aluminum alloy A5052 H34 (thickness 0.3 mm) to be joined. Sputter etching on the SUS304 surface of the two-layer rolled joined body was carried out under the condition of flowing Ar as a sputter gas under a pressure of 0.3 Pa and a plasma output of 700 W for 12 minutes. As follows, Ar was flowed in under conditions of 0.3 Pa and plasma output of 700 W for 12 minutes.
The SUS304 surface and A5052 of the two-layer rolled joint after the sputter etching treatment are rolled down at a normal temperature with a rolling roll diameter of 100 mm to 250 mm and a rolling line load of 0.5 tf / cm to 5.0 tf / cm. Joining was performed by roll pressure welding at a rate of 0 to 5% to obtain a three-layer rolled joined body of A5052 / SUS304 / A5052.
This rolled joined body was subjected to batch heat treatment at 300 ° C. for 1 hour to produce a rolled joined body for electronic equipment having a total thickness of 0.583 mm.

[Thickness of stainless steel layer / aluminum alloy layer]
Obtain an optical micrograph of the cross section of the rolled joined body obtained in Example 25, measure the thickness of the stainless steel layer and each aluminum alloy layer at any 10 points in the optical micrograph, the average value of the values obtained Was calculated.

[surface hardness]
Using a micro Vickers hardness meter (load 200 gf), the surface hardness (Hv) of the stainless steel layer was measured according to JIS Z 2244 (Vickers hardness test-test method).
Using a micro Vickers hardness meter (load 50 gf), the surface hardness (Hv) of each aluminum alloy layer was measured according to JIS Z 2244 (Vickers hardness test-test method). The results are summarized in Table 4.

[Evaluation results]
From the results in Table 4, the three-layer rolled joined body composed of the stainless steel layer and the aluminum alloy layer is expressed by the following formula (1).
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 11.18 (1)
It was found that the deformation height can be suppressed to 400 μm or less by satisfying the above. A deformation height of 400 μm or less can be evaluated as a range that does not adversely affect the components mounted inside the casing when the rolled joined body is used as the casing of the electronic device.
Moreover, following formula (2)
_{_{^{_{H S T S 2 + H AA}}}} T AA 2 ≧ 14.72 (2)
By satisfying the above, it has been found that the deformation height is further reduced and can be suppressed to 340 μm or less. The deformation height of 340 μm or less is a range that does not adversely affect the components mounted inside the case when the rolled joined body is used as the case of the electronic device. Increase in battery capacity, increase in mounting capacity, and the like can be achieved.

Next, rolled joined bodies of Reference Examples 1 to 10 were produced, and the following characteristics were evaluated.
(Reference Example 1)
SUS304 (thickness 0.2 mm) was used as the stainless steel material, and aluminum alloy A5052 (thickness 0.8 mm) was used as the aluminum alloy material. Sputter etching was performed on SUS304 and A5052. Sputter etching for SUS304 was performed under conditions of 0.1 Pa, plasma output 700 W, 13 minutes, and sputter etching for A5052 was performed under conditions of 0.1 Pa, plasma output 700 W, 13 minutes. did. SUS304 and A5052 after sputter etching treatment were joined by roll pressure welding at normal temperature at a rolling roll diameter of 130 to 180 mm and a rolling line load of 1.9 tf / cm to 4.0 tf / cm. A rolled joint was obtained. This rolled joined body was subjected to batch annealing at 300 ° C. for 2 hours. About the rolling joined body after annealing, the rolling reduction of the stainless steel layer, the aluminum alloy layer, and the rolled joined body (whole) was calculated from the thickness of the original plate before joining and the final thickness of the rolled joined body, respectively.

(Reference Examples 2-4 and 6-7)
Except for changing the thickness of the aluminum alloy material of the original plate, the reduction ratio at the time of joining by changing the pressing force at the time of joining, and / or the annealing temperature to the predetermined values, the same as in Reference Example 1 to Reference Examples 2 to Rolled joints of 4 and 6-7 were obtained. In Reference Example 2, the rolled joined body produced in Example 15 was cut out and used for evaluation. Regarding the thickness of the rolled joined body, the value is different between Example 15 and Reference Example 2, but it is a slight difference and is substantially the same.

(Reference Example 5)
The rolled joined body produced in Example 16 was cut out and used for evaluation.

For the rolled joined bodies of Reference Examples 1 to 7, 180 ° peel strength was measured for the rolled joined body after joining and before annealing, and the final rolled joined body after annealing. For the rolled joined bodies of Reference Examples 1 to 7, the tensile strength and elongation were measured, and the bending workability and the drawing workability were evaluated. Measurement of 180 ° peel strength, tensile strength and elongation, and evaluation of bending workability and drawing workability were performed as follows.

[180 ° peel strength]
A test piece having a width of 20 mm was prepared from the rolled joined body, the stainless steel layer and the aluminum alloy layer were partially peeled off, the aluminum alloy layer side was fixed, and the stainless steel layer was 180 ° opposite to the aluminum alloy layer side, and the tensile speed was 50 mm. The force (unit: N / 20 mm) required for tearing off when pulled at / min was measured using a Tensilon universal material testing machine RTC-1350A (manufactured by Orientec Co., Ltd.).

[Tensile strength]
Tensilon Universal Material Testing Machine RTC-1350A (Orientec Co., Ltd.) is used, and the specification of special test piece No. 6 described in JIS Z 2201 is used as the test piece, in accordance with JIS Z 2241 (metal material tensile test method). Measured.

[Elongation]
It measured according to the measurement of elongation at break described in JIS Z 2241 using the test piece of the tensile strength test.

[Bending workability]
Bending was performed by the V-block method (metal fitting angle 60 °, metal fitting R0.5, load 1 kN, test material width 10 mm, JIS Z 2248).

[Drawing workability]
Cylindrical drawing was performed and evaluated using a mechanical Eriksen tester (Universal Thin Plate Tester Model 145-60 manufactured by ERICHSEN). Drawing conditions were as follows.
Blank diameter φ: 49 mm (diaphragm ratio 1.63) or 55 mm (diaphragm ratio 1.83)
Punch size φ: 30mm
Punch shoulder R: 3.0
Die shoulder R: 3.0
Wrinkle pressure: 3N
Lubricating oil: Press working oil (No. 640 (manufactured by Nippon Tool Oil))
Molding temperature: Room temperature (25 ° C)
Molding speed: 50 mm / sec Drawing workability was evaluated in five stages shown in Table 5 below. The higher the value, the better the drawing processability. It should be noted that the blank diameter of 55 mm (drawing ratio: 1.83) is stricter than the blank diameter of 49 mm (drawing ratio: 1.63).

Table 6 shows the configurations, production conditions, and evaluation results of the rolled joined bodies of Reference Examples 1 to 7.

From Table 6, the reference examples 1 and 2 in which the pressing force at the time of joining was increased to increase the reduction rate of the aluminum alloy layer were compared with the reference example 6 in which the reduction rate of the aluminum alloy layer was less than 5%. Although the peel strength after joining was the same before annealing, the peel strength after annealing was remarkably improved, indicating that the drawing workability was improved. Further, from Reference Examples 2, 3 and 7, there is an appropriate annealing temperature range for increasing the peel strength of the rolled bonded product after annealing, which is considered to be 200 ° C. to 370 ° C. in batch annealing. Moreover, when the thickness of the aluminum alloy material is thin, the peel strength of the rolled joined body can be increased. In this case, in particular, the peel strength improvement width before and after annealing was large (Reference Example 4).

Further, it was found from comparison with the results of Reference Examples 8 to 10 using pure aluminum below that the peel strength is less likely to be higher when the aluminum layer is an aluminum alloy than when pure aluminum is used. This is because aluminum alloy has higher hardness than pure aluminum and is not easily deformed. In the first place, it is difficult to increase the peel strength at the time of bonding, and it is easy to generate an intermetallic compound at the bonding interface by annealing. This is presumably because the peel strength is lowered.

(Reference Example 8)
SUS304 (thickness 0.2 mm) was used as the stainless steel material, and pure aluminum A1050 (thickness 0.85 mm) was used as the pure aluminum material. Sputter etching was performed on SUS304 and A1050. Sputter etching for SUS304 was performed under conditions of 0.1 Pa and plasma output of 700 W for 13 minutes, and sputter etching for A1050 was performed under conditions of 0.1 Pa and plasma output of 700 W for 13 minutes. did. SUS304 and A1050 after sputter etching were joined by roll pressure welding at room temperature at a rolling roll diameter of 130 mm to 180 mm and a rolling line load of 1.9 tf / cm to 4.0 tf / cm. Got. This rolled joined body was subjected to batch annealing at 300 ° C. for 2 hours.

(Reference Examples 9 and 10)
The rolled joined bodies of Reference Examples 9 and 10 were obtained in the same manner as Reference Example 8 except that the rolling reduction and / or the annealing temperature at the time of joining by changing the pressure applied at the time of joining were changed to predetermined values.

The rolled joined bodies of Reference Examples 8 to 10 were evaluated in the same manner as described above. Table 7 shows the configurations, production conditions, and evaluation results of the rolled joined bodies of Reference Examples 8 to 10.

From Table 7, even when the aluminum layer is pure aluminum, as in the case of the aluminum alloy, the peel strength after bonding is equivalent by increasing the rolling reduction during bonding, but the peel strength after annealing is the same. It can be remarkably increased, and it has been shown that the peel strength improvement width before and after annealing can be increased.

DESCRIPTION OF SYMBOLS 1 Rolling joined body 2 Aluminum alloy layer 3 Stainless steel layer 5 Case for electronic devices 10 Base 20 Steel ball 30 Acrylic tube 40 Weight 50 Back surface 51 Side surface A Flat portion

All publications, patents and patent applications cited in this specification are incorporated herein by reference in their entirety.

Claims

A rolled joined body for electronic equipment mainly composed of metal,
It consists of a stainless steel layer and an aluminum alloy layer,
The thickness T S (mm) and surface hardness H S (Hv) of the stainless steel layer, and the thickness T AA (mm) and surface hardness H AA (Hv) of the aluminum alloy layer are expressed by the following formula (1).
H S T S 2 + H AA T AA 2 ≧ 11.18 (1)
However,
0.2 ≦ T S + T AA ≦ 1.6
0.05 ≦ T S ≦ 0.6
0.1 ≦ T AA ≦ 1.1
A rolled joined body for electronic equipment.
Following formula (2)
H S T S 2 + H AA T AA 2 ≧ 14.72 (2)
The rolled joined body for an electronic device according to claim 1, wherein:
A rolled joined body for electronic equipment mainly composed of metal,
It consists of a stainless steel layer and a pure aluminum layer,
The thickness T S (mm) and surface hardness H S (Hv) of the stainless steel layer, and the thickness T A (mm) and surface hardness H A (Hv) of the pure aluminum layer are expressed by the following formula (3).
H S T S 2 + H A T A 2 ≧ 17.93 (3)
However,
0.2 ≦ T S + T A ≦ 1.6
0.05 ≦ T S ≦ 0.6
0.1 ≦ T A ≦ 1.1
A rolled joined body for electronic equipment.
Following formula (4)
H S T S 2 + H A T A 2 ≧ 22.52 (4)
The rolled joined body for electronic devices according to claim 3, wherein
The ratio of the thickness T S of the stainless steel layer to the total thickness of the rolled conjugate, electronics rolling assembly according to any one of claims 1 to 4 is 60% or less than 10%.
The surface hardness H S of the stainless steel layer is, electronic equipment rolling assembly according to any one of claims 1 to 5, 200 or more 380 or less.
An electronic device casing mainly composed of metal,
The back and / or side includes a rolled joined body composed of a stainless steel layer and an aluminum alloy layer,
The thickness T S (mm) and surface hardness H S (Hv) of the stainless steel layer, and the thickness T AA (mm) and surface hardness H AA (Hv) of the aluminum alloy layer are expressed by the following formula (1).
H S T S 2 + H AA T AA 2 ≧ 11.18 (1)
However,
0.2 ≦ T S + T AA ≦ 1.2
0.05 ≦ T S ≦ 0.6
0.1 ≦ T AA ≦ 1.1
A housing for electronic equipment.
Following formula (2)
H S T S 2 + H AA T AA 2 ≧ 14.72 (2)
The electronic device casing according to claim 7, wherein:
An electronic device casing mainly composed of metal,
The back and / or side includes a rolled joined body composed of a stainless steel layer and a pure aluminum layer,
The thickness T S (mm) and surface hardness H S (Hv) of the stainless steel layer, and the thickness T A (mm) and surface hardness H A (Hv) of the pure aluminum layer are expressed by the following formula (3).
H S T S 2 + H A T A 2 ≧ 17.93 (3)
However,
0.2 ≦ T S + T A ≦ 1.2
0.05 ≦ T S ≦ 0.6
0.1 ≦ T A ≦ 1.1
A housing for electronic equipment.
Following formula (4)
H S T S 2 + H A T A 2 ≧ 22.52 (4)
The electronic device casing according to claim 9, wherein:
The ratio of the thickness T S of the stainless steel layer to the total thickness of the rolled conjugate, electronics housing according to any one of claims 7-10 is 60% or less than 10%.
The surface hardness H S of the stainless steel layer is an electronic equipment enclosure according to any one of claims 7 to 11 is 200 or more 380 or less.