Yes, you can solder/braze aluminum. No, you can’t use regular solder or brazing rod.
Zinc is the magic ingredient
Soldering and brazing are actually the same process. Both terms mean attaching metal pieces together, using another metal alloy that melts at a lower temperature than the work pieces. People may argue about exact definitions, but soldering generally means lower temperatures using lead or tin alloys, and brazing generally means higher temperatures using brass alloys. But the overall process is still the same.
Aluminum can be soldered/brazed as well. The key is having the right alloy. Common lead, tin, or brass solder/brazing rod won’t work. You need a zinc/aluminum alloy. If you get the right alloy, it is as easy as soldering anything else.
Aluminum brazing rod is sold under a number of brand names, often infuriatingly named something like “Alumiweld” or “low-temperature aluminum welding rod”. Terrible names, because while soldering and brazing are essentially the same process, welding is fundamentally different. Argh! Welding means to actually melt and fuse the metal in the work pieces together. This aluminum brazing rod works great, but it isn’t welding.
In any case, this aluminum brazing rod works great. I’ve used it to attach aluminum blocks and tubing in a variety of configurations, all with a propane torch. I’ve had the best results by first melting a thin layer on each work surface (“tinning” them) and then bringing them together.
It works great; I highly recommend it. Give it a try!