Is there a need for RA flux or solder? - Page 1
Forum section: electronics / beginners

author: jayjr1105
author_rank: Regular Contributor
timestamp: August 16, 2020, 08:06:20 pm
content: I'm curious as to why someone would want rosin based solder or flux when no-clean stuff exists. I have a no clean pen and syringe but have RA core solder. Should I switch to no clean core solder as well? I am genuinely curious about this, and don't know the advantages of one or the other.

author: tooki
author_rank: Super Contributor
timestamp: August 16, 2020, 09:23:01 pm
content: Rosin is generally more active. And for most applications, it doesn’t need to be removed, either, being just cosmetic. No-clean tends to smell worse, not be as active, and if you do want to remove it, it’s often much, much harder to clean thoroughly. However, it’s safer to leave for sensitive applications (though remember that it’s only safe if it’s been heated to soldering temperatures, which is not guaranteed with liquid or paste flux when hand soldering), and most no-clean fluxes are designed to handle higher temperatures, which can be an advantage with lead-free solder.

author: coppice
author_rank: Super Contributor
timestamp: August 16, 2020, 09:29:15 pm
content: The no clean fluxes can be really hard to clean off, but you often need to clean them off. If you need low board surface leakage, you'll probably need to clean it off. If you want to minimise the effects of humidity on the PCB's surface you'll probably want to clean it off. If its just some mundane digital board no clean flux is usually fine.

author: David Hess
author_rank: Super Contributor
timestamp: August 17, 2020, 01:42:57 am
content: A more active flux is suited to rework and repair.

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 17, 2020, 04:23:22 pm
content: Quote from: jayjr1105 on August 16, 2020, 08:06:20 pmrosin clean good, it's cheap and good rosin residue actually protect from impurities etc the pcb.looks ugly but it's good.I worked also with expensive flux with Metcal 5000 bga soldering machine, so for some apps you need this fluid solutions.don't forget most fluxes are rosin-based.in fact, it depends on app.you have a friend who need you to repair his boiler control board, rosin solid is ok.you need to replace fancy bga chip, that's different.I saw some tech people using fancu flux with small result and guys with cheap diluted rosin in a bottle making miracles...regards,pierre

author: jayjr1105
author_rank: Regular Contributor
timestamp: August 17, 2020, 08:55:54 pm
content: Thanks for the input. I watched this video and it helped me understand a bit more

author: tooki
author_rank: Super Contributor
timestamp: August 18, 2020, 08:15:53 am
content: Quote from: jayjr1105 on August 17, 2020, 08:55:54 pmJust beware that the creator of that video didn’t realize that some of those are acid based fluxes.

author: knotlogic
author_rank: Regular Contributor
timestamp: August 18, 2020, 01:55:04 pm
content: Quote from: tooki on August 16, 2020, 09:23:01 pmNo clean fluxes being harder to clean off and needing to be heated fully to be safe, do you think an RMA flux might be a better option for a hobbyist?

author: wraper
author_rank: Unknown
timestamp: August 18, 2020, 02:02:07 pm
content: Many no-clean fluxes are rosin based. No-clean simply means low amount of residues which can be left on PCB. It does not say anything about flux composition.

author: Peabody
author_rank: Super Contributor
timestamp: August 18, 2020, 02:11:05 pm
content: Quote from: knotlogic on August 18, 2020, 01:55:04 pmRadio Shack solder, which many hobbyists (including me) used for many years, is RA flux solder. I rarely bothered to clean it off. Still available online.

author: tooki
author_rank: Super Contributor
timestamp: August 18, 2020, 04:13:56 pm
content: Quote from: knotlogic on August 18, 2020, 01:55:04 pmHonestly, if given a choice, yes. But neither is a bad option. When using added flux, you’re likely going to want to clean it anyway, since it can be a bit messy.Quote from: wraper on August 18, 2020, 02:02:07 pmIt doesn’t mean low-residue necessarily. It means that it’s OK to leave on. Some are low-solids rosin, others are synthetic, others are extra refined rosin.For sure, the no-clean fluxes in wire solder cores aren’t low-residue, just neutral and pale residue.