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Forum Index : Microcontroller and PC projects : Water or rosin based solder flux?
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| BrianP Senior Member  Joined: 30/03/2017 Location: AustraliaPosts: 292 |
Hi all In a previous thread there was a mention of the availability of water-based soldering fluxes. As I will soon need to purchase some more solder flux I did some quick research on Dr. G but as frequently happens I am now confused about the pros & cons of each. As far as I can determine a water-based flux has a higher activity than a rosin-based one, & because of this it is more important the remove any remaining residue - with water. However, with the very close mounting of SMD components to the board it seems that the relatively high surface tension of water can prevent the flux removal underneath these parts, leaving the possibility of longer term corrosion. I have always used in the past a rosin-based flux (I believe the standard these days is an RMA (rosin-medium-activation) product. My question is, have any of you shedders had any experience, or have any knowledge in this area, & if so what would you recommend? Seems like small issue, but maybe with potential ramifications...  Cheers Brian P. |
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trippyben Regular Member  Joined: 26/06/2011 Location: AustraliaPosts: 91 |
Yes, with water based flux you must wash post-soldering. Many of the entry level PCB washing machines are dishwasher based, thus for hand washing you really need hot water and some sort of pressure to help clean it off. For hand assembly you are probably best sticking with any flux that is specified as 'no clean'. With this type of flux the activity is complete post soldering heat cycle and can be safe to leave on the assembly. However for SMD work you tend to end up with a sticky mess that subsequently attracts other contaminants. I've also had issues with crystal circuits being affected by the residual flux, thus for any SMD work I'm doing by hand I always wash with isopropanol and compressed air. And for through hole work I leave the no clean flux on the board. Beware, some of the rosin core fluxes are highly active post soldering and must be washed - especially the older ones. Double check for the 'no clean' variant. |
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Poppy Guru  Joined: 25/07/2019 Location: GermanyPosts: 486 |
Wasn´t there something about "no clean" depending on soldering temperature (and time), so that all flux needs to be boiled off to get free of any residues?!? ... so that it could be too hot at last? Some more Info´s: http://www.circuitnet.com/experts/67321.html Edited 2019-09-11 22:07 by Poppy  Andre ... such a GURU? | ||||
| BrianP Senior Member Joined: 30/03/2017 Location: AustraliaPosts: 292 |
Thanks guys - you have confirmed my suspicions. I think I'll stick with the rosin-based for now. There seems to be a fair amount available on E-bay, but there are warnings about fake knock-off stuff. What would you expect to pay for something like 10ml RMA223 solder flux? B (edit) Do we spell it Ebay or E-bay? Edited 2019-09-12 10:22 by BrianP |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1577 |
Could anyone suggest a GOOD solder and Flux? I read lead solder is being banned from next year. heard that before but no idea if it's true or not. In any case I need some more solder and I have got a few Duds so would like something like the Old roll Of Dick smith solder I have now. Never had any trouble with that, unlike some others. |
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palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1801 |
I'm also in the market for another roll of fine solder. I think I will get it from RS components, I can't imagine them selling rubbish. I did buy some off Ebay once and it was useless. As for flux I use a flux pen from Jaycar. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| ceptimus Senior Member Joined: 05/07/2019 Location: United KingdomPosts: 130 |
For home use, I still think it's much better to use solder containing lead. You can still buy it on Ebay. The solder that doesn't contain lead is much more difficult to use: you need a higher temperature iron, everything even more scrupulously clean than for solder with lead*, and even then it's tricky. *With leaded solders, cleanliness is very important, but the lead-less solders you have to get everything super clean, and then clean it again. Even just touching the legs of the components you're soldering with clean hands is enough to spoil the job. I've built a little fan unit that sucks air gently through some activated carbon filters. It's just a small computer fan in a 3-D printed frame that holds the filter. I stand it behind the job I'm working on and it provides just enough air flow so that the smoke is sucked into the filter rather than the usual case where convection currents due to body heat cause it to waft into your face. Obviously not as good as proper professional fume extracting systems, but for the limited amount of soldering I do, I think it's probably adequate and certainly better than nothing. |
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| BrianP Senior Member Joined: 30/03/2017 Location: AustraliaPosts: 292 |
Fortunately I still have a couple reels of 60/40 solder (normal & fine) with a large amount left on each. With the not large amount of soldering I do these days they should last a while yet. I do have a reel of unleaded stuff but it doesn't seem to get used... I agree about the fumes extraction. It makes one shudder to think of what we never used to do during our "working" life - we must be worth a bit on the recycle market now with all the heavy metals we must have soaked up over the years.  B |
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| Poppy Guru Joined: 25/07/2019 Location: GermanyPosts: 486 |
... and don´t forget to wash your hands after each job and no finger licking or nail biting (or eating or drinking at all) while working!  I dissolve pure rosin in pure isopropanol taking that kind of being usual for bow instruments and that works fine yet, but actually I do not know if it is that perfect from a chemical point of view. But any residues can be washed off with pure isopropanol very easily and a very good solder with lead and a proper flux core is essential for me (but this already is hard to find today ... for me  ).Andre ... such a GURU? | ||||
| IanT Regular Member Joined: 29/11/2016 Location: United KingdomPosts: 84 |
I don't know about Australia - but as far as I'm aware the restrictions on the use of leaded solder here in UK apply to any application involving potable water (e.g. plumbing use). It is certainly still possible to purchase leaded solders from suppliers such as Farnell UK. For instance: https://uk.farnell.com/multicore-loctite/d622-500g-reel/solder-wire-60-40-180-deg-0-71mm/dp/419345 Going back to lurking now - but always enjoy my Backshed daily update! :-) Regards, IanT |
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| Poppy Guru Joined: 25/07/2019 Location: GermanyPosts: 486 |
In Germany it is not so easy, the product I got used to just vanished and no directly convincing substitute seems to be available, so I have to make a new survey to find something really satisfying. Generally leaded solder seems to step back from market more and more ... next time I will stock up instantly for at least some longer time. Andre ... such a GURU? | ||||
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