Electricity: electrical systems and devices – Discharging or preventing accumulation of electric charge
Reexamination Certificate
1999-04-27
2001-12-18
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Discharging or preventing accumulation of electric charge
C361S220000
Reexamination Certificate
active
06331927
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for shielding static electricity sensitive components. More particularly, the present invention relates to the use of a screen formed of static electricity dissipative material for shielding components.
BACKGROUND OF THE INVENTION
Assembly of certain components which are sensitive to static electricity often takes place on microelectronics production floors. It is, therefore, necessary to provide a barrier between such components and any generators of static electricity which may be found on the production floor. The most common generators of static electricity are insulators. Insulators, which have a resistance factor of 10
11
(ohms) &OHgr; or more, when rubbed together will hold a static charge. Examples of insulators include clothing, hair, certain plastic products, Styrofoam, paper, non-treated Lexan (acrylic), certain computer monitors, non-safe plastic wrap, and non-safe rubber items.
Conventional procedure is to assemble such static electricity sensitive components in a segregated electrostatic discharge (“ESD”) safe area. This is generally accomplished by erecting a barrier around the ESD safe area, providing a thirty-six inch buffer zone between the ESD safe area and the remainder of the production floor, or the non-ESD safe area.
Providing such a buffer zone is an inefficient use of the available production floor. Thus, there exists a need for a barrier which makes a more efficient use of the production floor while still protecting ESD sensitive components.
SUMMARY OF THE INVENTION
The present invention provides a ground shield having a screen formed of a static electricity dissipative material, at least one fastening structure for anchoring the screen, and a structure for extending and retracting the screen. In an aspect of the invention, die shield is ground by the fastening structure. In another aspect of the invention, the shield is ground through connection with an overhead conductive grid.
In one embodiment of the invention, the static electricity dissipative material has a resistance factor of no greater than 10
4
ohms.
In another embodiment of the invention, the structure for extending and retracting the screen includes a motor.
In another embodiment of the invention, the screen includes a spring loaded mechanism used to extend and retract the screen.
The present invention also provides a method of shielding ESD sensitive components including the steps of putting ESD sensitive components in a first area separated from a second area, partitioning the first area from the second area using at least one shield having a screen.
REFERENCES:
patent: 4427114 (1984-01-01), Howell et al.
patent: 5014849 (1991-05-01), Becker
patent: 5315255 (1994-05-01), Bettinger
patent: 5383097 (1995-01-01), Delucia et al.
patent: 5410372 (1995-04-01), Lee
patent: 5448405 (1995-09-01), Clausen et al.
patent: 5791485 (1998-08-01), Carbonneau
patent: 6058000 (2000-05-01), Koenck et al.
Jackson Stephen W.
Micro)n Technology, Inc.
Perkins Coie LLP
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