MOTOROLA
INC.
Communications
Sector
SAFE
HANDLING
OF CMOS
INTEGRATED CIRCUIT DEVICES
Many
of
the integrated circuit devices used in com-
munications equipment are
of
the CMOS (Complemen-
tary Metal Oxide Semiconductor) type. Because
of
their
high open circuit impedance, CMOS ICs
are
vulnerable
to
damage from static charges. Care must be taken in
handling, shipping,
and
servicing them
and
the
assemblies in which they are used.
Even
though
protection devices
are
provided in
CMOS
IC
inputs, the protection
is
effective only against
overvoltage in the hundreds
of
volts range such as are
encountered in an operating system.
In
a system, circuit
elements distribute static charges
and
load the CMOS
circuits, decreasing the chance
of
damage. However,
CMOS circuits
can
be
damaged by improper handling
of
the modules even
in
a system.
~
To
avoid damage
to
circuits, observe the following
handling, shipping,
and
servicing precautions.
1.
Prior
to and while servicing a circuit module,
particularly after moving within the service area,
momentarily touch
both hands to a bare metal earth
grounded surface. This will discharge any static charge
which may have accumulated
on
the person doing the
servicing.
NOTE
Wearing
Conductive
Wrist
Strap
(Motorola
No.
RSX-4015A) will minimize
static buildup during servicing.
WARNING
When wearing Conductive Wrist Strap,
be careful near sources
of
high voltage.
The good
ground
provided
by
the wrist
strap will also increase the danger
of
lethal shock from accidentally touching
high voltage sources.
2.
Whenever possible, avoid touching any elec-
trically conductive parts
of
the circuit module with your
hands.
3.
Normally, circuit modules can be inserted
or
removed with power applied to the unit. However,
check the
INSTALLATION
and
MAINTENANCE
sec-
tions
of
the manual as well as the module schematic
diagram to insure there are no objections
to
this prac-
tice.
4. When servlcmg a circuit module, avoid
carpeted areas, dry environments,
and
certain types
of
clothing (silk, nylon, etc.) because they contribute to
static buildup.
5.
All electrically powered test equipment should
be grounded.
Apply
the ground lead from the test
equipment to the circuit module
before connecting the
test probe. Similarly, disconnect the test probe prior to
removing the
ground lead.
6.
If
a circuit module
is
removed from the system,
it
is
desirable
to
lay it
on
a conductive surface (such as a
sheet
of
aluminum foil) which
is
connected
to
ground
through
lOOk
of
resistance.
WARNING
If
the aluminum foil
is
connected directly
to
ground,
be cautious
of
possible elec-
trical shock from contacting the foil
at
the
same time as
other
electrical circuits.
7.
When soldering, be sure the soldering iron
is
grounded.
8.
Prior
to
connecting jumpers, replacing circuit
components,
or
touching CMOS pins (if this becomes
necessary in the replacement
of
an
integrated circuit
device), be sure to discharge any static buildup as
described in procedure
1.
Since voltage differences can
exist across the
human
body, it
is
recommended
that
on-
ly
one
hand
be used
if
it
is
necessary to
touch
pins
on
the
CMOS
device
and
associated
board
wiring.
©
Motorola,
Inc. 1982
All Rights Reserved
Printed in
U.S.A.
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#@If\VIfi@@d
1301
E.
Algonquin
Road, Schaumburg, II. 60196
v
68P81106E84-C
12/10/82-
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