Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1997-09-12
2001-05-01
Cuchlinski, Jr., William A. (Department: 3661)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S034000, C174S034000, C428S561000, C148S668000
Reexamination Certificate
active
06225556
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic shielding sheet, its manufacturing methods and uses. The sheet can be freely wound on electronic devices such as cables.
2. Description of the Related Art
Nowadays, a remarkable progress in intelligence and communication techniques and the use of computers, organization of network systems (to connect each computer with communication circuits) has been developing in a wide range of industrial fields. In the manufacturing field, many types of control devices, measuring equipment, and sensors are used accompanied by factory automatization through computers. But a problem arises due to leakage of magnetism into the surroundings from cables (such as those which supply electric current or which are used for communication), motors, magnetrons, and magnetic driving instruments. Leakage also occurs due to crosstalk between adjacent wiring boards, malfunctions in the electronic circuits in a computer. In order to prevent such a leakage of magnetism or to stop the effect of the leakage of magnetism, use of so-called magnetic shielding materials has become a common practice.
For such magnetic shielding materials, rolled plates made of permalloy or shaped members made by forging and pressing are used. These plates and shaped members are manufactured from plate materials by cutting, bending, and welding and they are used to shield rooms and spaces (where computers and other devices which contain electronic circuits are installed) from the effect of magnetism. To shield an electronic device having a particular size and shape, a number of receptacle forming members similar in form must be made by forging, pressing, and assembling.
But permalloy is expensive and requires extensive processing as described above and the shield materials from permalloy are also expensive. In addition the processing causes localized distortion which results in reduction of the magnetic shield characteristics. Moreover, the increase in weight and space for installation restricts the extent of application. It has been also extremely difficult to wrap or paste the shield material in the form of a plate on surfaces of various cables, in and outside electronic devices, or inside a computer room because of low flexibility in shape. Particularly, it has been almost impossible to put shields after laying cable, after assembling electronic device, or after completion of computer room construction.
An object of the present invention is to solve the conventional technical disadvantages described above and provide magnetic shielding sheets, manufacturing methods, and cables which include the shielding sheet. It is also an object of the invention to provide magnetic shielding sheets which are able to freely and easily cover on individual object, with no increase in weight and space, with a low manufacturing cost, regardless of the source of the occurrence, shape and size of the object, position of its installation, conditions, and the surrounding spatial situation.
SUMMARY OF THE INVENTION
The present invention is obtained by processing metal having a magnetic shield capability such as permalloy into a thin flexible lap sheet.
The magnetic shielding sheet relating to the present invention is made of alloys having a magnetic shield capability and is flexible having a thickness of less than 100 &mgr;m. The alloy includes soft magnetic metals such as Fe, Ni, and Cu as or alloys of Fe—Ni series, Fe—Cr—Al series, and Fe—Co—V series.
Among the alloys above described, Fe—Ni series having Ni content in the range of from 30% to 85 wt % are used. Such alloys may also have Mo in an amount which is less than 8 wt % and/or Cu in an amount which is less than 8 wt %.
The Fe—Ni series alloys described above include permalloy alloys such as PB permalloy (Fe-45% Ni), PC permalloy-1 (Fe-80% Ni-several percent of Mo), PC permalloy-2 (Fe-78% Ni-several percent of Mo- several percent of Cu), 12% Mn-9.6% Cu-6% Fe—Ni, PD permalloy (Fe-36% Ni) which is invar alloy having a low coefficient of expansion in nature, alloys of Fe-42% Ni, Fe-52% Ni, and alloys having these alloys as bases.
The reason of setting the content of Ni to be from 30 wt % to 85 wt % is that the shielding effect of the magnetism begins to lower from below 30 wt % while the effect disappears from above 85 wt %, just inviting an increase in cost.
And the reason of adding less than 8 wt % of Mo and/or Cu is to increase magnetic permeability, restrict magnetic anisotropy, and eliminate magnetostatics. From above 8 wt %, these effects are saturated.
In the Fe—Cr—Al series alloys, 10 wt % to 17 wt % of Cr is added to increase corrosion resistance and high frequency characteristic, and 0.01 wt % to 5.0 wt % Al is added to increase electrical resistance and high frequency characteristic. The reason of setting each upper limit to be 8 wt % is that the characteristics are saturated from the upper limit.
In the Fe—Co—V series alloys, 40 wt % to 60 wt % of Co is added to increase saturation magnetic flux density, and 0.1 wt % to 5 wt % of V is added to improve electrical resistance, high frequency characteristic, and easiness of processing. When the content exceeds the upper limit, the effects are saturated. This is the reason of the upper limit to be 5 wt %.
The magnetic shield sheets include the sheets coated with an adhesive layer on a part or all of a surface to ensure the shielding, though the shielding effect may be maintained even by only wrapping the sheet on the surface of an electrical insulating material such as a conductive cable. The sheet also includes a laminated sheet with plastic film or sheet, paper or corrugated card board for reinforcement or insulation at least on a surface for the protection of objects to be shielded while handling for transfer or shielding of magnetic recording media or after shielding.
Further, a cable having a sheath layer wound by the magnetic shield sheet on the periphery of electrical insulating layer around a communication cable is included.
The present invention also includes a method for manufacturing a flexible magnetic shielding sheet of less than 100 &mgr;m in thickness to obtain the magnetic shield sheet above described. The method consists of a process of repeated warm rolling and annealing, and a process of magnetic annealing, for a plane alloy plate having magnetic shielding capability. The plate or sheet which is processed to have a predetermined thickness by the warm rolling, embeds work strain and locked-in stress. These strain and stress are eliminated by annealing. Thus warm rolling and annealing are repeated several times till the thickness of the plate becomes less than 100 &mgr;m. Then magnetic annealing is applied at the designated temperature range to impart magnetic shield capability. The magnetic shielding sheet obtained is as flexible as foil so that it may be rolled up, for instance, on a reel.
REFERENCES:
patent: 4992329 (1991-02-01), Ishii et al.
patent: 5260128 (1993-11-01), Ishii et al.
patent: 5326646 (1994-07-01), Nakashima et al.
patent: 5462809 (1995-10-01), Berkowitz
patent: 5573857 (1996-11-01), Auger
patent: 5574249 (1996-11-01), Lindsay
patent: 5585196 (1996-12-01), Inomata et al.
Bacon & Thomas
Cuchlinski Jr. William A.
Daido Tokushukou Kabushiki Kaisha
Mancho Ronnie
LandOfFree
Magnetic shield sheet and method for manufacturing thereof,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic shield sheet and method for manufacturing thereof,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic shield sheet and method for manufacturing thereof,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2502490