Preventing Electrostatic Discharge Damage
Electrostatic discharge (ESD) damage occurs when electronic cards or components are improperly handled,
and can result in complete or intermittent failures. All line cards consist of a printed circuit card that is fixed
in a metal carrier. Electromagnetic interference (EMI) shielding and connectors are integral components of
the carrier. Although the metal carrier helps to protect the cards from ESD, use an antistatic strap each time
you handle the modules. Handle the carriers by the edges only; never touch the cards or connector pins.
Always tighten the captive installation screws on all system components when you are installing them. These
screws prevent accidental removal of the module, provide proper grounding for the system, and help to ensure
that the line card connectors are properly seated in the backplane. To ensure proper grounding and mechanical
support, the captive screws on the front cards should be tightened to 10-12 in-lbs and the rear PIC cards should
be tightened to 6-8 in-lbs. Never use cordless or corded drills to tighten screws; power screwdrivers and hand
tools are acceptable.
Caution
Static electricity can harm delicate components inside your system. To prevent static damage, discharge static
electricity from your body before you touch any of your system components. As you continue to work on
your system, periodically touch an unpainted metal surface on the computer chassis.
The following guidelines can prevent ESD damage:
• Always use an ESD-preventive wrist or ankle strap and ensure that it makes good skin contact. Before
removing a card from the chassis, ensure that the chassis is grounded to the rack.
• Handle line cards by the faceplate and carrier edges only; avoid touching the card components or any
connector pins.
• When removing a card, place the removed module component-side-up on an antistatic surface or in a
static-shielding bag. If the module will be returned to the factory, immediately place it in a static-shielding
bag.
• Avoid contact between the modules and clothing. The wrist-strap protects the card from ESD voltages
on the body only; ESD voltages on clothing can still cause damage.
• When transporting a sensitive component, first place it an antistatic container or packaging.
• Handle all sensitive components in a static-safe area. If possible, use antistatic floor pads and workbench
pads.
For safety, periodically check the resistance value of the antistatic strap. The measurement should be between
1 and 10 megohms.
Caution
Plant Wiring Guidelines
When planning the location of the new system, consider the distance limitations for signaling, EMI, and
connector compatibility, as described in the following sections.
Cisco Converged Broadband Routers Hardware Installation Guide
49
Prepare to Install
Preventing Electrostatic Discharge Damage
