Michael,

The heat gun I use is a gas powered soldering tool with 'hot air' nozzle. These things are sold by Weller, ERSA and others. Weller also has hot air SMT stations, but these are far more expensive; the cheapest (the WAD100) is over 700 euro and they require a compressed air supply.

You can buy solderpaste in syringes, to which a nozzle can be attached. I use the smallest nozzle (0.4mm dia.) which gives good control over the doseage. For standard SO devices I apply a drop to each individual pad. With a bit of practise, the size of the drop can be controlled in such a way that you will have no excess paste. If there is any excess, the high surface tension of the molten tin will ensure that it is either 'pulled' toward the nearest pin/pad or is formed into a tiny ball, which can easily be removed with fluxcleaner and a brush.


Rob.