What it looks like: You shat all over the board.
What it smells like: Nasty chemicals but only when hot.
What it does: it helps distribute heat, and causes the solder to be less viscuous and stick to metals readily.
What it feels like to start using it: Wow, it’s like I just gained one year of soldering experience!
What it feels like to remove it from the board after soldering: Aargh… I swear, one more board and I go buy an ultrasonic cleaner. (Some brands are easier but I usually need to employ a spudger, brush, then alcohol annd Q-tip)
Note that some solder comes with a core that contains flux or some similar substance of that effect.
Cleans and keeps the solder points clean. Prevents oxygen from reaching the solder joint
- It removes the oxide layer from existing surfaces so the solder sticks and flows better
- It increases surface tension of the liquid solder so you get a nice round shape and no whiskers and less bridges
- It helps distribute the heat a bit. It works a little bit like thermal paste, especially when the contact area between the tip and the pad/component is very small.
Generally, flux is your friend and soldering without flux is terrible.
