Safe Handling Of Cmos And Ldmos Devices - Motorola MTP700 Basic Service Manual

MAINTENANCE

Safe Handling of CMOS and LDMOS Devices

Complementary metal-oxide semiconductor (CMOS) devices are used in this family of
radios, 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, troubleshoot-
ing, and repair.
Handling precautions are mandatory for CMOS circuits and are especially important in
low humidity conditions. DO NOT attempt to disassemble the radio without first referring
to the following CAUTION statement.
CAUTION: This radio contains static-sensitive devices. Do not open the radio unless you
!
are properly grounded. Take the following precautions when working on this unit:
MTP700/MTP750 Portable Radios / Basic Service Manual
• 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 the Motorola Static Protection Assembly
(part number 0180386A82), which includes 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 are
Motorola part number RSX-4015.)
• 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.
• If at all 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.
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