I have some PCB's made and I need to mount some 0603 SMT parts on the board. I built a small reflow oven and am almost ready to start mounting parts but don't know what solder paste to purchase. I hear a lot of people talking about lead free solder paste but I don't know why I'd want that or if I if I should use leaded. They are just personal prototype boards and the reflow oven is located inside, in a large open room. There are lots of options on digikey for solder paste but I'd appreciate some advice on what to use and why. Thanks in advance!

 

Leaded solder makes prettier joints, melts at a lower temperature, and does not carry the risk of tin whiskers forming that might cause shorts, though tin whiskers are known to grow on lead-free solder joints..