Over-Molded Pad-Array Carrier (Ompac) - Motorola GTX 2000 Service Manual

GTX/GTX LTR/LTS 2000 Portable Radios Service Manual
power desoldering station, remove the excess
solder from the pads.
2. To replace a chip component using a solder-
ing iron, select the appropriate micro-tipped
soldering iron and apply fresh solder to one of
the solder pads. Using a pair of tweezers, posi-
tion the new chip component in place while
heating the fresh solder. Once solder wicks
onto the new component, remove the heat
from the solder. Heat the remaining pad with
the soldering iron and apply solder until it
wicks to the component. If necessary, touch up
the Þrst side. All solder joints should be
smooth and shiny.
3. To replace a chip component using hot air,
select the hot-air hand piece and reßow the
solder on the solder pads to smooth it. Apply a
drop of solder paste ßux to each pad. Using a
pair of tweezers, position the new component
in place. Position the hot- air hand piece
approximately 1/8" above the component and
begin applying heat. Once the solder wicks to
the component, remove the heat and inspect
the repair. All joints should be smooth and
shiny.

Over-Molded Pad-Array Carrier (OMPAC)

CAUTION
ASFIC U701 is an OMPAC. It must be
kept in a sealed bag with dessicant in the
bag (in a Òdry boxÓ as supplied by the
Motorola Parts Department prior to use.
I f t h e O M PA C i s a m b i e n t f o r a n
unknown amount of time or for more
than 96 hours, then it must be baked for
at least eight hours at 260 û F (185û C).
CAUTION
If neighboring OMPAC components are
heated above 365û F (185û C), they will
suffer die-bond delamination and possi-
ble ÒpopcornÓ failure.
During all repair procedures, heating neighboring
components can be minimized by:
¥ Using upper heat only. using the correct size
heat-focus head, approximately the same size as
the carrier being replaced.
¥ Keeping the heat-focus head approximately 1/
8" (0.3cm) above the printed circuit board when
removing or replacing the device.
1. To remove the OMPAC, select the R-1319A
Air-Flow Station and the appropriate heat-
focus head (approximately the same size as
the OMPAC. Attach the heat-focus head to the
June 1999
chimney heater. Adjust the temperature con-
trol to approximately 415û F (215û C) 445û F
(230û C) maximum. Adjust the airßow slightly
above the minimum setting. Apply the solder
paste ßux around the edge of the OMPAC.
Place the circuit board in the R-1319A's circuit
board holder, and position the OMPAC under
the heat-focus head. Lower the vacuum tip
and attach it to the OMPAC by turning on the
vacuum pump. Lower the heat-focus head
until it is approximately 1/8" (0.3cm) above
the carrier. Turn on the heater and wait until
the OMPAC lifts off the circuit board. Once the
part is off, grab it with a pair of tweezers and
turn off the vacuum pump. Remove the circuit
board from the R-1319A's circuit board holder.
2. To replace the OMPAC, the solder pads on
the board must Þrst be cleaned of all solder to
ensure alignment of the new chip carrier. Pre-
pare the sight by using solder wick and a sol-
dering iron to remove all solder from the
solder pads on the circuit board. If a power
desoldering tool is available, it can be used
instead of the solder wick. Clean the solder
pads with alcohol and a small brush. Dry and
inspect. Ensure that all solder is removed.
Once the preparation is complete, place the
circuit board back in the R-1319A's circuit
board holder. Add solder paste ßux in the
trench of the ßux block and spread it using a
one-inch putty knife. Flux the OMPAC by
placing it in the trench of the ßux block. Once
the ßux is applied, place the OMPAC on the
circuit board, making certain that it is oriented
correctly on the board. Position the heat-focus
head over the OMPAC and lower it to approx-
imately 1/8" (0.3cm) over the carrier. Using
the same heat and airßow setting used to
remove the OMPAC, turn on the heater and
wait for the carrier to reßow (heating and
reßow should take longer than 60 seconds).
Once the carrier reßows, raise the heat-focus
head and wait approximately one minute for
the part to cool. Remove the circuit board and
inspect the repair. No cleaning should be nec-
essary.
Shields
1. Removing and replacing the shields will be
done with the R-1319A, using the same heat
and airßow proÞle used to remove and
replace OMPAC components.
Place the circuit board in the R-1319A's holder.
Select the proper heat focus head and attach it
to the heater chimney. Add solder paste ßux
around the base of the shield. Position the
shield under the heat-focus head. Lower the
68P02945C75-A
Maintenance
Repair Procedures and Techniques
6-3