madcitysw said:
Since I did also have a hot air station, though it would be easier to solder those smds that I need to solder using the hot air instead of hand soldering them. Don't you still need some kind of flux to solder then hand anyway?
You can use regular solder with excellent results. The technique is (for TQFP-80):
1. tin your pads. Put some rosin over the pads then run a drop of molten solder using your regular soldering iron. You'll get nice little bumps on your pads covered with thin film of rosin.
2. Put a little rosin on IC pins. Kester RMA-186 pencil is handy for dispensing small amounts of rosin. You can also wet a piece of paper towel and then put an IC over wet spot for a second.
3. Position IC over pads. Don't sweat it - the part will self-center thanks to surface tension of molten tin. So as long as your pins are positioned over right pads you are fine.
4. Heat up your hot-air to 300 degC. Set the air flow to low 20%. This is important - molten rosin is slicky and the strong stream of air will be moving your part out of alignment. Now start heating your part from above - if it's big, you can move your air stream around the part. When you heat it up enough, you will see your part settle down and level on the pads. Put your air gun away, let the thing cool down and inspect your work under strong magnifier.
On the attached picture you can see the result - it's TQFP package with 0.5mm pitch. Pins are perfectly aligned and the amount of tin is right.
The hardest part is to put the correct (small and uniform) amount of tin on the pads before soldering. It's relatively easy with small pads (see above); bigger pads tend to take more tin than necessary. For 0603 and bigger sizes I found it easier to tin the part itself instead of the pads it is going to - you overdo it just a little, then, when the tin melts the excess spreads on the pad.
Also, there are air soldering tutorials on sparkfun site - check them out.