Page 77 - Robot Builder's Bonanza

46 SAFETY FIRST (AND ALWAYS)

Figure 4-1 An antistatic wrist strap
draws static electricity from your body,
helping to prevent damage to sensitive
electronic components. Be sure to use
the wrist strap according to the
manufacturer’s instructions.

Just to be on the safe side, you should treat all semiconductors as delicate. You don’t need
to go overboard; things that aren’t (usually) sensitive to ordinary static discharge include resis-
tors, capacitors, diodes, motors, or any mechanical device, such as a switch or relay.

USING AN ANTISTATIC WRIST STRAP
If you live in a dry climate or where static is an ongoing problem, consider using an antistatic
wrist strap whenever you work with sensitive electronics. This strap, like the one shown in
Figure 4-1, grounds you at all times and prevents static buildup.
To use, put the strap around your wrist, then connect the clip to any grounded or large
metallic object. A nearby computer (plugged in) or the frame of a metal desk or bookshelf are
good choices. If you have an antistatic desk or floor pad it will likely have a metal stub on it
that you can connect the wrist strap to. Even if the pad is itself not grounded, the idea here is
that it dissipates the static because of its large surface area.
Though you may read otherwise, it’s not a good idea to go sticking your wrist strap into
the ground hole of an electrical wall socket. It’s too easy to accidentally plug yourself into one
of the other holes and receive a shock.

STORING STATIC- SENSITIVE DEVICES

Plastic is one of the greatest sources of ESD. Bench- top storage containers are often made of
plastic, and it’s a great temptation to dump everything into these containers. Avoid that.
Invariably, static electricity will develop and a sensitive part could become damaged.
Unfortunately, there’s no way to tell if a component has become damaged by ESD just by
looking at it. You won’t know anything is wrong until you actually try to use the component.
Static- sensitive electronics are best stored using one of the following methods. All work by
connecting (grounding) the leads of the component together, thereby diminishing the effect
of a strong jolt of static electricity. Note that none of the storage methods is 100 percent
foolproof.

• Antistatic mat. This mat looks like a black sponge, but it’s really conductive foam. Be sure
to save your antistatic foam! You can use it to make pressure sensors, as described in
Chapter 42, “Adding the Sense of Touch.”)
• Antistatic pouch. Antistatic pouches are made of a special plastic coated on the inside
with a metallic layer. Many are resealable so you can use them again and again.

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