According to BEST Inc BGA rework station is a repair system to solder and desolder defects during soldering SMD components as empty soldering, short circuit and others. Main differences of rework stations are heat source and heat mode; Take example only upper heat or upper and lower both heating, some can set temperature curve. Considering protecting components, the upper and lower both heating system are better. To prevent PCB warping during repairing, preheat function in the rework system is better. PCB fix, BGA position and others are important consideration. More information at http://www.soldertools.net/bga-stencils-stencilquik/