Electricity: electrical systems and devices – Discharging or preventing accumulation of electric charge – Specific conduction means or dissipator
Reexamination Certificate
2000-06-29
2003-09-09
Berhane, Adolf D. (Department: 2838)
Electricity: electrical systems and devices
Discharging or preventing accumulation of electric charge
Specific conduction means or dissipator
C002S167000
Reexamination Certificate
active
06618236
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head handling glove used for handling a magnetic head, particularly an MR (magnetoresistive) or a GMR (giant magnetoresistive) head in a clean room.
2. Description of the Related Art
Conventionally, when components easily damaged by ESD (electrostatic discharge) are produced in clean rooms, the processes are automated so that such components can be produced without allowing them to come into contact with human hands. However, in the case of certain components, such as MR head components or GMR head components, which can easily be damaged by ESD, it has traditionally been difficult to avoid contact with human hands during the production process, since some manufacturing processes require the handling of MR heads or GMR heads by the human hands of an operator, such as when an operator attaches an MR head or head to a suspension using forceps. In such circumstances, a problem can occur if an operator builds up a static charge which is then discharged onto the MR head or GMR head damaging the component.
A prior art solution to this problem is that wrist straps are worn by operators to prevent the buildup of static charges. However, the amount of static charge that can build up on an operator significantly depends upon the skin resistance of individual operators. In the case of operators with dry skin, the wrist strap is not effective due to the high resistance of such operators' skin, so that any slight movements made by an operator will result in increases in the quantity of static charge that is built up on the operator. Thus, wrist straps have not worked with such dry-skinned operators.
Published Unexamined Patent Application No. 63-75179 discloses a technology for preventing a glove from acquiring a static charge by application of an antistatic powder compound. The antistatic powder compound is formed by uniformly dispersing carbon black in vinyl chloride resin and plasticizer, and then coating the surface of a glove with the compound. Although this technology may limit the buildup of static charges, it cannot be used for the purpose of the present invention, namely for handling MR or GMR heads, as it is insufficient especially for preventing electric charge leakage occurring at the fingertips of the glove.
Published Unexamined Patent Application No. 7-189002, although not specifically directed to the prevention of static electrical charges, does disclose a technology for dust prevention and electromagnetic shielding by disclosing a laminated electromagnetic shielding cloth comprising conductive fiber coated with Teflon or urethane on the surface or the reverse surface. However, this technology also cannot be used for the purpose of the present invention, namely for handling MR or GMR heads, since the conductive fiber disclosed in Published Unexamined Patent Application No. 7-189002 is not grounded, and thus, in the instance where a dry-skinned operator's body has built up a static charge, it cannot prevent a glove worn by such an operator from also building up a static charge.
Therefore, the purpose of the present invention is to solve the problems described above by making it possible to prevent ESD and the buildup of unwanted static electric charges, as well as to provide a magnetic head handling glove that is suitable for clean room use.
SUMMARY OF THE INVENTION
In the present invention, a magnetic head handling glove comprises a conductive glove having a first coating layer on an outer surface and a second coating layer on an inner surface of the conductive glove. The first and second coating layers of the present invention are formed, respectively, by coating the outer and inner surfaces of the conductive glove with a dissipative material. Furthermore, in an embodiment of the present invention, the second coating layer of the conductive glove may not be formed, and only a first coating layer of a dissipative material is formed on the outer surface of the conductive glove. In this case, the glove is not directly grounded but is grounded through a high resistive path of about 1 M&OHgr;.
The dissipative materials used in forming the first and second coating layers of the conductive glove are materials that can be used in a clean room. Thus, when a glove of the present invention is used in a clean room, possible contamination from the direct use of the conductive glove may be prevented. Furthermore, in an embodiment of the present invention, the conductive glove is connected to a grounding conductor without any substantial resistance by a wire connecting the conductive glove to an electrical ground. As a result, the accumulation of electrostatic charges on an operator's body and ESD may be prevented.
In a preferred embodiment of the present invention, the sheet resistance of the dissipative material is 10
4
ohm/sq. to 10
12
ohm/sq. Materials with resistance in this range are between insulators and conductors. Preferably, the dissipative material comprises nitrile rubber or polyurethane. With either material, the glove can be used in clean rooms without acquiring static charge buildup by friction as would an insulator. Furthermore, in an embodiment of the present invention, where only the outer surface is coated with dissipative material, then the conductive glove is grounded through a high resistance of about 1 M&OHgr;.
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IBM Technical disclosure Bulletin, vol. 19, No. 6, Nov. 1976.
Sasao Yasuhiro
Tsuwako Kazushi
Yamaguchi Katsushi
Yamamoto Hirokazu
Berhane Adolf D.
Gill William D.
Nunnelley Lewis L.
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