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Black Colored Steel Sheet Having Excellent Electromagnetic Shielding Property, Electromagnetic Shielding Member, and Electromagnetic Shielding Case

Inactive Publication Date: 2007-11-15
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0013] The present invention solves the problems described above. It is an object of the present invention to provide a surface-treated steel sheet that can effectively reduce an electromagnetic wave leaking from a seam or a joint of a case formed of the surface-treated steel sheets to exhibit excellent electromagnetic shielding property and that has an excellent black appearance and high corrosion resistance.
[0015] Heretofore, the surface roughness of a Zn—Ni-plated steel sheet having a blackening-treated layer has been defined on the basis of a common roughness, such as an arithmetical mean roughness Ra, to improve the electromagnetic shielding property. However, as a result of diligent and repeated investigations to solve the problems described above, the present inventors have found that it is insufficient to define the surface roughness of a steel sheet on the basis of a common roughness, such as an arithmetical mean roughness, to effectively improve the electromagnetic shielding property, and that the number of peaks per inch (PPI) is important. The present inventors also have found that the thickness of a blackening-treated layer also has an effect on the electromagnetic shielding property.
[0026] The present invention can provide a black colored steel sheet that can effectively reduce an electromagnetic wave leaking from a seam or a joint of a case formed of the surface-treated steel sheets to exhibit excellent electromagnetic shielding property and that has an excellent black appearance and high corrosion resistance.
[0027] The present invention can also provide an excellent electromagnetic shielding member all or part of which is formed of the black colored steel sheet.
[0028] The present invention can also provide an excellent electromagnetic shielding case formed of the black colored steel sheets.

Problems solved by technology

However, as a result of diligent and repeated investigations to solve the problems described above, the present inventors have found that it is insufficient to define the surface roughness of a steel sheet on the basis of a common roughness, such as an arithmetical mean roughness, to effectively improve the electromagnetic shielding property, and that the number of peaks per inch (PPI) is important.

Method used

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  • Black Colored Steel Sheet Having Excellent Electromagnetic Shielding Property, Electromagnetic Shielding Member, and Electromagnetic Shielding Case
  • Black Colored Steel Sheet Having Excellent Electromagnetic Shielding Property, Electromagnetic Shielding Member, and Electromagnetic Shielding Case
  • Black Colored Steel Sheet Having Excellent Electromagnetic Shielding Property, Electromagnetic Shielding Member, and Electromagnetic Shielding Case

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0075] Samples Nos. 1 to 13 in Table 1 were manufactured according to the steps of an annealed cold-rolled steel sheet→temper rolling (control of surface roughness)→electroplated Zn—Ni coating→anodic oxidation (blackening treatment)→formation of a coating film, or an annealed cold-rolled steel sheet→blasting (control of surface roughness)→electroplated Zn—Ni coating→anodic oxidation (blackening treatment)→formation of a coating film. The samples were different in the thickness of a blackening-treated layer and the Ra, the PPI, and the coating weight of coating film after the blackening treatment. The thickness of a Zn—Ni-plated layer formed by Zn—Ni electroplating was 2 μm. The thickness of the blackening-treated layer was controlled by the electrolysis time and pH in the anodic oxidation.

[0076] A predetermined coating weight of coating film was deposited by applying a paint composition containing a metal ion, a water-soluble organic resin, a water-dispersible organic resin, a glyc...

example 2

[0104] Table 2 illustrates the electromagnetic shielding property of various samples (Nos. 5, 6, 8, 13, and 15) illustrated in Table 1, when the samples were applied to an exterior portion 10 and a lid 11 of the tower-type PC case illustrated in FIG. 3.

[0105] The electromagnetic shielding property of the tower-type PC case was evaluated as follows.

[0106] The electromagnetic shielding property of electronic equipment and electrical equipment including a case formed of a sample was measured in an open area test site at a distance of 3 m as described in note 2 of Table 4.6 in technical standards V-3 / 2005.04, 4.3 tolerance of radiated emission electric field strength issued by the Voluntary Control Council for Interference by Information Technology Equipment (VCCI). The acceptability was determined by a Class B criterion.

[0107] Pass: satisfy Class B

[0108] Fail: does not satisfy Class B

TABLE 2ExteriorElectromagneticCase No.portionLidshieldingRemarks1No. 5No. 6PassExample 132No. 6No...

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Abstract

A black colored steel sheet comprises a Zn—Ni-plated steel sheet having a blackening-treated layer and a coating film on the surface of the Zn—Ni-plated steel sheet. The blackening-treated layer has a thickness of 0.01 to 1.0 μm. The Zn—Ni-plated steel sheet having a blackening-treated layer has an arithmetical mean roughness Ra of 0.7 to 2.0 μm and the number of peaks per inch (PPI) of at least 180.

Description

TECHNICAL FIELD [0001] The present invention relates to a black colored steel sheet having excellent electromagnetic shielding property. In particular, the present invention intends to advantageously improve the electromagnetic shielding property of a black colored steel sheet, not to mention a black appearance and corrosion resistance. [0002] The present invention also relates to an electromagnetic shielding member and an electromagnetic shielding case, which use the black colored steel sheet having electromagnetic shielding property. BACKGROUND ARTS [0003] Conventionally, black colored steel sheets having a blackening-treated surface have widely been used, for example, in business machines, such as personal computers and copying machines, household electrical appliances, such as air conditioners, automobile parts, and interior building materials. In general, the black colored steel sheets are manufactured by applying a black paint to a galvanized sheet iron or by performing a blac...

Claims

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Application Information

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IPC IPC(8): C23C28/00
CPCC23C2/18C23C22/24Y10T428/12493H05K9/0088C25D5/48C23C28/00C25D11/34
Inventor UMEBAYASHI, RIETADA, CHIYOKONAKAMARU, HIROKI
Owner JFE STEEL CORP
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