The Value Chain of Rework
Separating a single SMD from the PCB after all the solder joints between these two parts have been molten is generally the first step and called desoldering.
Afterwards the pad array on the conductor board is cleaned from old tin. It is quite easy to remove these rests by heating them up into the area of melting temperatures.
In principle the precise placement of the new unit onto the prepared pad array requires a highly accurate vision alignment system with high resolution and magnification which is controlled by a skilled operator. The smaller the pitch of the components the higher the demand on the precision equipment for the alignment.
Finally the just now placed SMD is soldered on the board. Reliable and high quality solder joints are created by an adapted solder profile which heats all the connections between the unit and the PCBA up to the area of melting temperatures and cools them properly down.
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