80-0276-F Datasheet, PDF (4/5 Pages) List of Unclassifed Manufacturers – System Level ESD Mitigation

System Level ESD Mitigation
Design Note
7. (Recommended) Tightly twist power wires and their returns together. The main power source in the system
is often a prime target for inductive coupling from ESD. Wires from a battery box are an example of this.
8. (Desirable) Try to use the following for all signals: twisted pair cable, coaxial cable or flat cable instead of
single wires. Put shrink tubing on wires if extra shielding is required.
9. (Desirable) Choose ESD safe components, like thick-film and carbon composition resistors instead of thin-
film resistors, if practical
10. (Desirable) Beware of substitute and second-source components that may be functionally equivalent, but
lack the ESD-immunity of the preferred components.
D. Making Your Enclosure More Resistant To ESD:
For enclosure design, the overall goal is to keep all ESD outside the enclosure. The best way to do this is to use
an electrically nonconductive (typically plastic) enclosure.
Plastic and other nonconductive enclosures, air space, and insulation can prevent ESD arcs from penetrating
inside the system (direct ESD). However, they provide no protection against ESD arcs outside the enclosure
(indirect ESD). To protect against these arcs, ensure greater than or equal to 20 mm path length between the
electronics and:
1. (Recommended) Any points that the user can touch, including seams, ventilation openings and mounting
holes. (ESD arcs can travel farther over the surface of a dielectric than they can through open air.)
2. (Recommended) Any ungrounded metal that the user can touch, including fasteners, switches, controls, and
indicators.
If practical and system cost allows, it's better to design with provisions for adding shields made of one of the
following materials:
1. (Desirable) Conductive filler in the plastic.
2. (Desirable) Silver, copper or nickel paint.
3. (Desirable) Mylar/copper or Mylar/aluminum laminates.
4. (Desirable) Zinc arc spray.
5. (Desirable) Thermoformed metal mesh with bonded junctions.
6. (Desirable) Sheet metal.
7. (Desirable) Vacuum metallizing.
Optimal shielding is less than or equal to 1 ohm/square resistance. Joints and edge treatment are critical, as are
arrangements for connecting bonding jumpers/wires.
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P/N 80-0276-F
© 2006 Sensory Inc.