qfn hand soldering

QFN package: LP3 (3mm x 3mm), all leads are at the bottom of the chip and also there is a big plate of ground at the back.

Wilson,
Since pads BSC is 20 mils, you'll need a good hand and experience to solder it. I reccomend to use a SMT hot air blower. If you do not have one, you can put the component over the PCB and put some SMT flux around it, to avoid connections between nearby pads. With a sharp apex soldering station, you can do it. Most of the times, extra soldering metal is not necessary for such small pads, if the PCB is coated at the PCB factory with soldering metal (over copper). For the big metal pad underneath I suggest to design the PCB with a via under the qfn package (take care, no solder masks under package, no tenting via) and solder it from the bottom side. Solder metal will flow through the via from the bottom layer to top, and will attach metal pad.

/pisoiu