Dell Latitude 5420 Rugged Service Manual page 63

The more difficult type of damage to recognize and troubleshoot is the intermittent (also called latent or "walking wounded") failure. The
following image shows an example of intermittent damage to a memory DIMM trace. Although the damage is done, the symptoms may
not become an issue or cause permanent failure symptoms for some time after the damage occurs.
Figure 9. Intermittent (Latent) Damage to a Wiring Trace
Do the following to prevent ESD damage:
• Use a wired ESD wrist strap that is properly grounded.
The use of wireless anti-static straps is no longer allowed; they do not provide adequate protection.
Touching the chassis before handling parts does not ensure adequate ESD protection on parts with increased sensitivity to ESD
damage.
Figure 10. Chassis "Bare Metal" Grounding (Unacceptable)
• Handle all static-sensitive components in a static-safe area. If possible, use anti-static floor pads and workbench pads.
• When handling static-sensitive components, grasp them by the sides, not the top. Avoid touching pins and circuit boards.
• When unpacking a static-sensitive component from its shipping carton, do not remove the component from the anti-static packing
material until you are ready to install the component. Before unwrapping the anti-static packaging, be sure to discharge static
electricity from your body.
• Before transporting a static-sensitive component, place it in an anti-static container or packaging.
The ESD Field Service Kit
The unmonitored Field Service kit is the most commonly used. Each Field Service kit includes three main components: anti-static mat,
wrist strap, and bonding wire.
Removing and installing components 63