Which Flux Kicks Ass? Moderators: adafruit_support_bill, adafruit

[HarvesterOfBeer]

I'm doing PTH and SMT prototyping/tinkering via soldering iron, hot air, and skillet. So far I've been using the Kester 186 RMA flux pen. This works ok, but I've been looking at getting some liquid flux and/or tacky rework flux.

Any suggestions on what flux is king of the hill? Kester 951? 2331-ZX?

Thanks!

[alphatronique]

Hi

i use Koki TF-M406L-3 and S03X7Ca-56M solder wire (lead-free) it work very well together
this permit to solder 100pin TQFPp 0.5mm pitch in ~12 sec by drag soldering
the only problem i find was it hard to rework/desolder

only problem it hard to find here in Canada i got it from adtool

Best regard

[electronbee]

For general use I like Kester 186. Its semi-liquid but won't "spill" like water. Kinda does a slow ooze. Its a non activated RMA flux. So, technically, you can leave it on the PCB when you are complete with your work but it will get tacky. Easy clean-up with alcohol.

For SMT use, I like CHIP QUIK SMD291. You can find them on eBay, Google for it, etc. Get a 10cc syringe as it comes with a needle which makes flux placement better. This flux also cleans up well with alcohol.

I use the Kester 186 for all my de/solder needs. I only use the tacky stuff for initial placement.

[pstemari]

RMA flux is "mildly" activated, for whatever little that may be worth. Stuff with non-activated R flux seems to be a bit hard to find, I assume because the ease of use/non-corrosive trade-off is tilted too far in the non-corrosive direction for most applications.

[HarvesterOfBeer]

So far I've just been using the 186. I tried some of the cheap liquid flux from DealExtreme, and it was banned. I think Im going to try the SMD291 next.

[Agent24]

I've no complaints with the flux-pen Sparkfun sells, except that it smells worse than the flux in my solder wire...

[Blind-Summit]

I also need to start using flux. Excuse me for being ignorant, but I've seen liquid flux, gels and also flux paste. What is the difference, and what is best for normal through-hole soldering? Some seem to require a brush, or a dropper bottle/pipette or even a syringe. I am guessing that the syringe is for SMD work primarily.

Secondly, I have also read about this no-clean flux, and also the other types that clean up with water or IPA (propyl-alcohol). I notice that my solder does splutter a little, leaving little bits of sticky flux/goop on the PCB which looks messy. Would I be best to get some IPA regardless?

With regard to the flux - any links to online stores or eBay would be most useful - and ideally from the UK please.

Thanks,

Alex

[Agent24]

Standard flux cleans off with flux cleaner or IPA (higher % the better)

No-Clean flux needs to be cleaned with a special cleaner apparently, or you can get residue.

[franklin97355]

I've seen liquid flux, gels and also flux paste. What is the difference,

The difference is viscosity. Also most solder you get has flux in its core and does not need additional flux. You can get wire solder in different alloys and with different fluxes. I use .020 to .031 dia kester 44 most of the time since it sits on my bench in a 1 pound spool and I have not used it up yet. I also have Alpha no clean in lead free .015 and some paste for SMD.

[ressotto]

The 951 no-clean is designed to not need cleaning off the board

[RobG]

#2331-ZX works great, but you have to make sure to wash it off and not leave any traces of it behind, and sometimes that's just not possible.
This is what will happen when you don't remove it:

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