Siemens Simatic PC Panel PC 870 Service Manual download pdf (Page 62)

Appendix B: ESD Guidelines

B-2

SIMATIC Panel PC 670 / 870 Operating Unit, Equipment Manual

Edition 07/02

Handling ESD assemblies

A general rule is that assemblies should be touched only when this cannot be avoided

in the course of the work that has to performed on them. Under no circumstances

should you touch device pins or circuitry when handling printed-circuit boards.

You should touch devices only if

S you are grounded by permanently wearing an ESD wrist strap or

S you are wearing ESD shoes or ESD shoe-grounding protection straps in conjunc-

tion with an ESD floor.

Before you touch an electronic assembly, your body must be discharged. The

simplest way of doing this is to touch a conductive, grounded object immediately befo-

rehand (e.g. bare metal parts of a cabinet, water pipe, etc.).

Assemblies should not be brought into contact with charge-susceptible and highly insu-

lating materials such as plastic films, insulating table tops and items of clothing etc.

containing synthetic fibers.

Assemblies should be deposited only on conductive surfaces (tables with an ESD coa-

ting, conductive ESD cellular material, ESD bags, ESD shipping containers).

Do not place assemblies near visual display units, monitors or television sets

(minimum distance to screen > 10 cm).

Measuring and modifying ESD assemblies

Perform measurements on ESD assemblies only if

S the measuring instrument is grounded (e.g. by means of a protective

conductor) or

S the measuring head has been briefly discharged before measurements are made

with a potential-free measuring instrument (e.g. by touching a bare metal control

cabinet).

When soldering, use only grounded soldering irons.

Shipping ESD assemblies

Always store and ship assemblies and devices in conductive packing,

e.g. metallized plastic boxes and tin cans.

If packing is not conductive, assemblies must be conductively wrapped before they are

packed. You can use, for example, conductive foam rubber, ESD bags, domestic alu-

minum foil or paper (never use plastic bags or foils).

With assemblies containing fitted batteries, make sure that the conductive packing

does not come into contact with or short-circuit battery connectors. If necessary, cover

the connectors beforehand with insulating tape or insulating material.

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Siemens Simatic PC Panel PC 870 Service Manual Page 62