Figure 3-19.TO mounting techniques.
The procedure for removal of plug-in TOs (with or without conformal coatings) is the same as that
used for a similarly mounted DIP or discrete component. The conformal coating is removed if required.
Leads are desoldered and gently lifted out of the board. Then board terminals and component leads are
In some plug-ins, the leads must be formed before they are placed in a circuit. Care should be taken
to ensure that seal damage does not occur and that formed leads do not touch the TO case. This would
result in a short-circuit.
When the new part or the one that was removed is installed, the leads are slipped through the spacer
if required, and the part is properly positioned (reference tab in the proper location). The leads are aligned
with the terminal holes and gently pressed into position. The part is soldered into place and visually
inspected. Then the card is tested and the conformal coating is replaced if required.
The removal of an imbedded TO package varies only slightly from the removal of other types of
mountings. First, the work area is masked and the conformal coating is removed if required. Then the
desoldering handpiece is used to remove the solder from each lead. When all leads are free, the TO is
pushed out of the board. If all the leads are free, the TO should slip out of the board easily. The package
should not be forced out of the board. Excessive pressure may cause additional damage. If the leads are
not completely free, the leads must be clipped and removed after the package is out of the board. This
process is shown in figure 3-20.