For aluminum it's not called soldering, it's called brazing but the process is fairly similar.

The best joints are made with alloys that melt only slightly below the temperature of the base aluminum, so it's a very tricky job, and requires a lot of practice. You can google "aluminum brazing" and get a lot of different mfgr.

There are other alloys out there with lower melting temperatures, and these are much easier (probably not as strong??).

http://www.muggyweld.com/super5.html

I've never personally tried this muggyweld alloy, but I know people who have used it with good bonds, but on what I would call "lightly loaded" parts including some automotive evaporators.