This video showed up in my feed. It looks like a couple of the fluxes, including the Kester no clean did some damage.
Not really the best comparison to our uses. Ofc if you leave a quite large amount of flux, a compound meant to help clean metal surfaces for solder adherence, it’s going to do just that to some degree. Our uses are neither bare copper nor large quantities. Kester 245 noclean for example you’re looking at a max 3% flux, which means an entire board might almost see the quantity of flux this guy put onto a copper plate. Additionally, we’re almost exclusively working on top of masked surfaces and tinned/prepped pads, both of which are way more resistant to flux than bare or even the enig copper.
This is true, but I do remember seeing keyboard assembly guides 2+ years ago, that recommended using either a flux pen or a syringe of flux, in addition to the flux present in our solder.
A couple of the top results from googling “keyboard flux”:
There’s essentially no need nowadays for extra flux except for some SMD work, which isn’t something everyone is doing. Even so, the same things listed above apply as to how much is being used, what materials it’s actually sitting on, and a point I forgot which is how much of it is gonna be left after baking off, which is less than you began with.