Not for the faint of heart, but in order to desolder surface mount integrated circuits (as opposed to caps or resistors)...
Examine the area around the target component. Identify any components which might come loose if their solder melts, or which might be damaged by excessive heat. Cover these in modeling clay (the dry stuff that stays soft forever).
Liberally coat the pins of the target chip with liquid solder flux. This helps the solder to melt by preventing oxidation of the solder.
Apply heat from a heat gun to the target chip. Using a pointy implement such as a dental pick, poke at the solder to see if it is softening. Move the heat gun in a circular motion to help with even heating.
On my Milwaukee heat gun, which is continuously adjustable (as opposed to just one or two heat settings) I find a setting of about 8 (~800F) will heat a chip and board enough to melt solder in approximately two minutes. Yes, I sat there and timed this several times. A measure of how often I hacked the UltraTek-66 into a VST Ultra66 way back when.
Once the solder is melting, check the joints to be sure that you don't have any cool ones. Gently pry under the chip with the pointy implement, but do not exert any force to speak of. Certainly, do not lift the board by lifting on the chip.
When the chip comes loose, you are done.
This method is also useful for removing soldered down DIP packages without damage.
After things cool a bit, conduct any needed clean up. Use desolder braid on the circuit board's pads to remove the remaining solder. Clean the board to get rid of flux residue. Remove all the modeling clay. Modeling clay close to the heat will probably be crunchy.
Examine the area around the target component. Identify any components which might come loose if their solder melts, or which might be damaged by excessive heat. Cover these in modeling clay (the dry stuff that stays soft forever).
Liberally coat the pins of the target chip with liquid solder flux. This helps the solder to melt by preventing oxidation of the solder.
Apply heat from a heat gun to the target chip. Using a pointy implement such as a dental pick, poke at the solder to see if it is softening. Move the heat gun in a circular motion to help with even heating.
On my Milwaukee heat gun, which is continuously adjustable (as opposed to just one or two heat settings) I find a setting of about 8 (~800F) will heat a chip and board enough to melt solder in approximately two minutes. Yes, I sat there and timed this several times. A measure of how often I hacked the UltraTek-66 into a VST Ultra66 way back when.
Once the solder is melting, check the joints to be sure that you don't have any cool ones. Gently pry under the chip with the pointy implement, but do not exert any force to speak of. Certainly, do not lift the board by lifting on the chip.
When the chip comes loose, you are done.
This method is also useful for removing soldered down DIP packages without damage.
After things cool a bit, conduct any needed clean up. Use desolder braid on the circuit board's pads to remove the remaining solder. Clean the board to get rid of flux residue. Remove all the modeling clay. Modeling clay close to the heat will probably be crunchy.