MTR3000 Maintenance and Disassembly/Reassembly: Safe Handling of CMOS Devices 14-3
14.4 Safe Handling of CMOS Devices
Complementary metal-oxide semiconductor (CMOS) devices are used in this family of stations, and
are susceptible to damage by electrostatic or high voltage charges. Damage can be latent, resulting
in failures occurring weeks or months later. Therefore, special precautions must be taken to prevent
device damage during disassembly, troubleshooting, and repair.
Handling precautions are mandatory for CMOS circuits and are especially important in low humidity
conditions.
DO NOT attempt to disassemble the base station/repeater without first referring to the following
CAUTION statement.
This base station/repeater contains static-sensitive devices. Do not open the base
station/repeater unless you are properly grounded. Take the following precautions
when working on this unit:
• Store and transport all CMOS devices in conductive material so
that all exposed leads are shorted together. Do not insert CMOS
devices into conventional plastic “snow” trays used for storage
and transportation of other semiconductor devices.
• Ground the working surface of the service bench to protect the
CMOS device. We recommend using a wrist strap, two ground
cords, a table mat, and a floor mat.
• Wear a conductive wrist strap in series with a 100k resistor to
ground (replacement wrist straps that connect to the bench top
covering can be ordered using the Motorola part number
4280385A59).
• Do not wear nylon clothing while handling CMOS devices.
• Do not insert or remove CMOS devices with power applied.
Check all power supplies used for testing CMOS devices to be
certain that there are no voltage transients present.
• When straightening CMOS Pins, provide ground straps for the
apparatus used.
• When soldering, use a grounded soldering iron.
• Where possible, handle CMOS devices by the package and not
by the leads. Prior to touching the unit, touch an electrical ground
to remove any static charge that you may have accumulated. The
package and substrate may be electrically common. If so, the
reaction of a discharge to the case would cause the same
damage as touching the leads.
C a u t i o n
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