Solder Flux: Which Type?

[FuzzMonkey]

Does anyone have any recommendation regarding which flux to use when soldering? I use flux-infused solder but bought some 'flux in a pen' when I was soldering some guitar pots and use it occasionally on guitar pedal PCBs for SMDs. Is rosin flux fine for use on guitar pedal PCBs? Any feedback and suggestions would be appreciated.

[somnif]

Rosin flux is fine. Bit of a sticky mess, and it's not the prettiest, but it works wonderfully.

The only stuff you want to avoid is the "acid flux" found in plumbing solder (and flux sold for plumbing use). That stuff is quite corrosive and will eventually eat through pcb traces (and may be conductive if I recall correctly).

Personally I use "no clean" flux solder, just because I got a good deal on it. Works fine, but doesn't smell as nice as rosin, so take that for what it's worth.

[FuzzMonkey]

Thanks for your feedback.

That's what I read, regarding the acid flux. I've been some clips on YouTube about making your own by resolving rosin in isopropanol alcohol. I was thinking of getting some rosin paste.

I've mostly been using it, as I said, for reworking a few SMD components on some pedal repairs. The stuff I have, 'flux in a pen', leaves some residue but easily cleans it up with a Q-Tip and a little IPA.

[pickdropper]

No Clean or RMA types should both work fine.  Do not use water soluble flux unless you are prepared to thoroughly clean the boards as it will eat away at the board if not removed (I know that's not intuitive).   As somnif mentioned, you want to avoid acid flux as well.

I've used a number of different types, but I find the most convenient is just a Kester 186 Flux Pen.  That's RMA type and I prefer it to the No Clean.  If you don't want it in a pen, you can buy it in a canister.

[FuzzMonkey]

Thanks. Will check it out the Kester flux pen. This is the one I am currently using (from Jaycar, an electronics store in New Zealand and Australia):

https://www.jaycar.co.nz/solder-flux-pen-12ml/p/NS3036