The OMPAC chip is supplied with solder balls, engineered to make perfect solder joints. No additional solder need be added to the pads; however, leftover solder on the pads/board must be removed completely, and the pad should be smooth, clean and tinned.

1. Use a soldering iron in conjunction with the wick gun—Motorola part number 66-80333E70 (as shown in Figure 7) to remove all residual solder from the pads of the chip area leaving clean and tinned pads. Do not use excessive heat or pressure, because pad damage and/or removal could result. If the pads are not smooth and shiny, use the hot air reflow procedure which follows to clean them. If the pads are acceptably clean and ready for reattachment, add a drop or two of the wetting solution directly on the pad area and proceed to the Replacement Procedure.

1a. If OMPAC replacement IMMEDIATELY follows removal of a chip, the skip this step, as pad prep and cleaning to remove oxidation is unnecessary. Otherwise, use the Prep Pen (Motorola Part Number 66-80333E75) supplied with the SMD Tool Kit to clean the pad area, as shown in the illustration. Then, using the IPA Cleaning Solution from the tool kit, continue to clean the area, being careful not to damage the pads by rubbing too hard or vigorously.

1b. After cleaning, place a few drops of wetting solution on the cleaned pads.

Replacement Procedure

1. hot air level the pads if needed. In most instances, sufficient tinning will remain on the pads to attach a new chip; but the surface may be rough, uneven, or have solder "icicles", making accurate placement of a new chip difficult. To hot air level, first place a drop or two of wetting solution on the pads. Then depress the foot pedal of the Chipmaster to initiate the heating cycle. The GREEN display will begin counting DOWN to zero. The solder will melt and become smooth; the solder should cover the pads completely and have a shiny appearance.

2. Remove the board and board holder assembly from beneath the Chipmaster nozzle (depress cylinder, slide holder and board out). Let the board cool to ambient temperature.

3. Next, apply a thin layer of no-clean flux paste to the OMPAC bonding area, so that the paste is evenly brushed and spread over the approximately 1/2 square area as shown in Figure 8. Pick up a replacement chip using the aforementioned tweezers from the SMD Tool Kit then place and center the OMPAC chip on the pads, within the boundaries of the registration lines marked on the board (again, refer to Figure 3). Make sure the chip has been placed as accurately as possible and the outer edges of the package are in proper registration with the site.

4. Carefully place the board under the Chipmaster and align the OMPAC chip with the bottom of the nozzle in the same manner as was done for removal. Center the component under the nozzle as accurately as possible.

5. Press the INDEX key on the Chipmaster controller ONCE and verify or enter the appropriate cycle time. The appropriate cycle time for reinstallation is the same as the removal time plus 30 second, to ensure good solder wetting.

a) Press ENTER; cycle time is recorded in the memory—depress the foot pedal to review;

b) Press the INDEX key TWICE to return to the Main Menu.

6. Depress the foot pedal to begin the heating cycle, hold down until the timer reaches zero.

7. Release the foot pedal to end the heating cycle and, after the RED temperature LED indicates 140°F, remove the board from the Chipmaster work area.