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
~areful
near sources
of
high voltage.
The good ground provided by the wrist
strap will also increase the danger
of
lethal shock from accidentially 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 servicing 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 1
OOk
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.
techni<§AI
wliUng
:~e~vica~
68P81106E84-C
12/10/82- PHI
1301
E.
Algonquin Road,
Schaumburg,
II.
60196
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