Topbuilding SMD boards with a $79 toaster ovenThis has been a journey for me, the whole surface mount technology thing. When I got my real start with surface mount, I purchased a hot air pencil system from Zephyrtronics . Basically, I have their 2MMZT-5-CLSD system.
While having a hot air pencil is good for rework and replacing the occasional IC, it is not the way to go when you have 100+ parts to solder onto a board! Getting paste dispensed in the proper amount, where it is needed, is very difficult with a syringe applicator. Also, the air stream tends to push the parts around on the board, or, since you are soldering one side of an IC at a time, the solder will cool and tend to lift (torque) the other side of the chip slightly. Without a precise control of the paste, there are the inevitable shorts and opens.
Having seen an article on Sparkfun as to solder paste stenciling with mylar stencils, I decided to give it a try, and I have been very pleased with the results!