The objective of this step is to remove the component while minimizing the impact to the PCB. The most common PCB defects that should be avoided include lifted pads, disturbed solder connections adjacent to the BGA rework area, solder balls in underfilled or conformally coated areas and component warping.
The basic requirements of this operation are the following:
Preheat the entire PCB between 75º C and 125ºC
Insure that all joints have a temperature greater than 190ºC (230ºC for lead free)
Make sure that all joint temperatures are less than 220ºC.
Insure no solder is smeared on the part bottom or edge which might aid in part reclamation
Maintain adjacent component temperatures to less than 180ºC (200ºC for lead free) in order to minimize the heat impact on these parts
*Note these temperatures assume standard Pb/Sn soldering temperatures