Motorola pro7100 Manuel de service télécharger pdf (Page 58)

3-4 Maintenance

To replace a chip component using hot air:

1. Use the hot-air hand piece and reflow the solder on the solder pads to smooth it. For components

having two or three solder connections, apply a dot of NO-CLEAN solder paste to the lead joints

before removal.

2. Apply a drop of solder paste flux to each pad. For dual leaded devices such as SOICs, TSOPs,

and quad leaded devices less than 20 leads, such as PLCCs and QFPs, apply a bead of solder

paste.

3. Using a pair of tweezers, position the new component in place. As component is removed, it will

carry away excess solder, leaving the ideal amount on the pads for their surface area.

4. Position the hot-air hand piece approximately 1/8” (0.3 cm) above the component and begin

applying heat. For an extensive discussion of chip component rework and other technical proce-

dures, order manual 6880309G53 from Motorola AAD.

5. Once the solder wicks to the component, remove the heat and inspect the repair. All joints should

be smooth and shiny.

Shields

Removing and replacing shields will be done with the R-1070 R1319A station with the temperature

control set to approximately 415°F (215°C) [445°F (230°C) maximum].

To remove the shield:

1. Place the circuit board in the R-1070’s holder.

2. Select the proper heat focus head and attach it to the heater chimney.

3. Add paste flux (Motorola P/N 6680333E71) around the base of the shield.

4. Position the shield under the heat-focus head.

5. Lower the vacuum tip and attach it to the shield by turning on the vacuum pump.

6. Lower the focus head until it is approximately 1/8” (0.3 cm) above the shield.

7. Turn on the heater and wait until the shield lifts off the circuit board.

8. Once the shield is off, turn off the heat, grab the part with a pair of tweezers, and turn off the vac-

uum pump.

9. Remove the circuit board from the R-1070’s circuit board holder.

To replace the shield:

1. Add solder to the shield if necessary, using a micro-tipped soldering iron.

2. Rub the soldering iron tip along the edge of the shield to smooth out any excess solder. Use sol-

der wick and a soldering iron to remove excess solder from the solder pads on the circuit board.

3. Place the circuit board back in the R1070’s R1319A circuit board holder.

4. Place the shield on the circuit board using a pair of tweezers.

5. Place a small bead of no-clean flux (Motorola P/N 6680333E71) around the tinned surface.

6. Position the heat-focus head over the shield and lower it to approximately 1/8” (0.3 cm) above the

shield.

7. Turn on the heater and wait for the solder to reflow. The R1319A will record removal time, add 30

to 40 seconds for replacement.

8. Once complete, turn off the heat, raise the heat-focus head and wait approximately one minute for

the part to cool.

9. Remove the circuit board and inspect the repair. No cleaning should be necessary.

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Motorola pro7100 Manuel de service Page 58

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