Electricity: electrical systems and devices – Discharging or preventing accumulation of electric charge
Reexamination Certificate
1999-12-29
2001-12-04
Sherry, Michael J. (Department: 2836)
Electricity: electrical systems and devices
Discharging or preventing accumulation of electric charge
C361S217000, C361S219000, C361S220000
Reexamination Certificate
active
06327131
ABSTRACT:
FIELD OF THE INVENTION
This invention relates, in general, to the transportation and storage of components sensitive to electrostatic discharge, and more particularly, to the grounding of carts used to transport components.
BACKGROUND OF THE INVENTION
Carts are often used to transport semiconductor components from one location to another. However, the semiconductor components may be damaged by electrostatic discharge during the transportation. Therefore, the carts should be grounded to protect the semiconductor components. One technique for grounding a cart includes dragging a grounding cable from the cart across a conductive floor, where the grounding cable consists of a metal ball on the end of a metal cable. Other techniques for grounding a cart includes dragging a chain from the cart across the conductive floor or using conductive wheels on the carts.
However, such grounding techniques do not provide a constant ground for the cart because the conductive floors commonly used in the art are not entirely conductive, but merely have a plurality of very small conductive regions on the floor. Therefore, the cart is not grounded when the grounding cable, the drag chain, or the conductive wheels move between conductive regions on the floor. Furthermore, while loading the semiconductor components onto the cart and while unloading the components from the cart, the cart remains stationary and may remain ungrounded during the entire loading and unloading process. Accordingly, the semiconductor components may still be damaged by electrostatic discharge using these common grounding techniques. One technique for grounding stationary carts uses a grounding cable that the user of a cart must connect from the cart to a grounding station. However, this technique is not automatic so the cart may inadvertently remain ungrounded.
Accordingly, a need exists for an improved grounding apparatus for a cart and an improved method of transporting components sensitive to electrostatic discharge. It is desired for the apparatus and the method to be inexpensive and easy to implement.
REFERENCES:
patent: 2549471 (1951-04-01), Hutchison
patent: 2753491 (1956-07-01), Legge
patent: 4321653 (1982-03-01), Takahashi
patent: 4415946 (1983-11-01), Pitts
patent: 4484250 (1984-11-01), Rzepecki et al.
patent: 4491894 (1985-01-01), Pitts
patent: 4720048 (1988-01-01), Maroney et al.
patent: 4885659 (1989-12-01), Nowell et al.
patent: 4934022 (1990-06-01), Lissner
Scheman Loren J.
Thomas Floyd L.
Motorola Inc.
Pickens S. Kevin
Sherry Michael J.
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