This paper discusses how to successfully profile a printed circuit board when reworking Ball Grid Array and Chip Scale Packages. 

Board Profiling for Production vs. Rework

If we consider profiling a PCB for reflow in production, we are generally concerned with achieving an even Delta T ( T) across all of the joints being soldered. This is accomplished by evenly heating both the top and bottomside of the whole board, generally through a multi-zoned convection reflow oven. The capacity of the oven would be appropriate to the size or thermal mass of the PCB and the production throughput requirements.