Flux Categories

[2X]

I am starting this thread especially for beginners in order to add informations about fluxes and misconceptions around the flux types and right uses. My favorite flux part numbers are the below.
Every link, opinion are welcome.

835-100ML
Very good for soldering cables and SMD but not for hot air/reflow and not easy in cleanning (because is rosin based)
https://mgchemicals.com/products/soldering-supplies/soldering-flux/rosin-flux/

NC551-10CC
Very good for soldering SMD and medium performance for hot air/reflow (because is rosin based)
https://www.chipquik.com/datasheets/NC551-10CC.pdf

SMD291
Medium performance for soldering SMD, very good performance for hot air/reflow (because is resin based) and not easy in cleanning in respect with REA
https://www.chipquik.com/datasheets/SMD291.pdf

RMA7
Very good performance for soldering SMD (because is Medium Activated), very good performance (higher viscosity in respect to others when it melts) for hot air/reflow and difficult in cleanning (because is rosin based)



Can A Plumbing Solder Be Used For Electronics?
https://blackdiamondtoday.com/blog/can-plumbing-solder-used-electronics/

Choosing Soldering Flux
https://www.circuitspecialists.com/blog/choosing-soldering-flux/

Flux Type Selection
https://evertiq.com/news/16783

Choosing the Correct Flux – Types and Their Advantages/Disadvantages?
https://www.pillarhouse.co.uk/technology/flux-choosing-the-correct-flux-type-technical-article

Choosing The Best Flux for High Quality Electronic Soldering
https://www.chemtronics.com/essential-guide-to-flux-for-soldering-electronics

Rosin Flux for Soldering – Flux Rosin Types and Classification
https://blog.gotopac.com/2020/03/24/rosin-flux-soldering-flux-rosin-types-classification/

What They Don’t Teach You About Solder Fluxes on PCBs
https://resources.altium.com/p/what-they-dont-teach-you-about-fluxes

What are halogens doing in a flux and what danger do they pose?
https://smans.com/en/knowledgeportal/what-are-halogens-doing-in-a-flux-and-what-danger-do-they-pose/

Electrochemical migration (ECM)
https://www.google.com/search?q=electrochemical+migration&rlz=1C1KNTJ_elGR1079GR1079&sourceid=chrome&ie=UTF-8

[tooki]

You say several times that particular fluxes are hard to clean “because rosin based”, but rosin fluxes are generally considered to be easy to clean with solvents. It’s the modern no-clean fluxes that tend to be very hard to clean. So what is it you consider to be easy to clean??

SMD291 is good. But I like SMD291NL even better — it handles higher temperatures for lead-free better without burning, and still works great for leaded solder, but its biggest advantage over the non-NL version is that the NL version is completely transparent amber, without any cloudiness. This makes it way easier to see what you’re doing.

Also, you should link to the manufacturers’ pages, not distributors.


The thread title is “flux categories” but you don’t actually explain the flux types at all! Never mind that there are numerous systems for categorization, and then orthogonal to that, the different forms in which each category of flux exists. That is, every type of flux (e.g. R/RMA/RA system, RO/RE/OR+L/M/H+0/1 system, or the F-SW system) exists as flux core wire, liquid, and paste/gel.

[2X]

I use Isopropyl Alcohol and cotton at the tip of tweezers for cleanning. Compare to these that I 've used I made a personal graduation about cleaning.

[tooki]

Use proper flux cleaner. Modern fluxes are not fully soluble in IPA. (Traditional rosin flux is.)

[tooki]

P.S. I updated my first reply after you responded, so you may want to reread it now.

[2X]

Use proper flux cleaner. Modern fluxes are not fully soluble in IPA. (Traditional rosin flux is.)

I had used the below flux cleaner but I didn't impressed with the results of the cleanning compared to IPA and also smells very bad. If you say that a flux cleaner cleans better than IPA then it will be like that. I will search to find and try another flux cleaner where at least his smell will be more "soft".
Manufacturer Part Number: 84009-AA

[tooki]

Use proper flux cleaner. Modern fluxes are not fully soluble in IPA. (Traditional rosin flux is.)

I had used the below flux cleaner but I didn't impressed with the results of the cleanning compared to IPA and also smells very bad. If you say that a flux cleaner cleans better than IPA then it will be like that. I will search to find and try another flux cleaner where at least his smell will be more "soft".
Manufacturer Part Number: 84009-AA

I’ve used Kontakt LR (aka Kontakt PCC) a lot, and it’s definitely better at cleaning than pure IPA, but the one I really like is Electrolube LFFR (lead-free flux remover). It cleans even better than Kontakt LR, and it smells a whole lot nicer (it uses orange terpenes as part of its solvent blend, which not only clean well but smell lovely).

[2X]

I found also the below cleaners and I wiil try one of them, but I am not sure for the results because on the datasheet shows that it needs 5 minutes in order to clean the PCB and also to put it on a secondary solvent in order to remove/rinsing residues/liquids from the clening step.


I am going to try the below:
COSOLV175-1.0
https://www.chipquik.com/store/product_info.php?products_id=330062

CHIPQUIK Flux Removers
https://www.chipquik.com/store/index.php?cPath=360

[MathWizard]

My current jar of cheap ebay stuff, it's like rosin mixed with wax. Trying to solder with it, well it's pretty weak stuff so it's lousy, but rarely have to worry about shorts with it. So anytime I have to work on SMD IC's, or something I can't easily clean, I use this.

The other stuff I use, MG Chemicals 8342 RA rosin, it's great for eating corrosion and wetting, but it has to be well cleaned off afterwards. There's not much issue with large solder balls, but it can leave a conductive residue, and it spits and crackles everywhere. I've had it get under traces, and mess up a PCB I solder on too many times.

On PCB's or protoboards, if I really want them clean, I use a toothbrush, ISP alcohol, and then soapy water. But yeah, I'm afraid too use that good stuff on chips and certain SMD stuff. I need to find something in between.

[2X]

I tried with hand cleaning the Flux Remover COSOLV175-1.0 but I am not impressed. I would say it dissolve flux residues 30% more easier than Isopropyl Alcohol and has smell were that is mildly affordable (with my nose at least). I use it only in special cases that I have plenty flux over hot air desoldering. I will continue to be fun of Isopropyl Alcohol.
Also, I found that this make a very good cleaning with hands and with ultrasound cleaners (not only in flux residues buy and in corrosion – I haven’t tried yet).

SWAS Safewash Super
https://electrolube.com/product/swas-safewash-super/

At 4:24 - SWAS Safewash Super

[tooki]

I tried with hand cleaning the Flux Remover COSOLV175-1.0 but I am not impressed. I would say it dissolve flux residues 30% more easier than Isopropyl Alcohol and has smell were that is mildly affordable (with my nose at least). I use it only in special cases that I have plenty flux over hot air desoldering. I will continue to be fun of Isopropyl Alcohol.

I’m not sure I’m understanding — if it cleans 30% better than IPA, why are you unsatisfied with it?

Also, I found that this make a very good cleaning with hands and with ultrasound cleaners (not only in flux residues buy and in corrosion – I haven’t tried yet).

SWAS Safewash Super
https://electrolube.com/product/swas-safewash-super/

At 4:24 - SWAS Safewash Super

I just got an ultrasonic cleaner at work, and I found SWAS to work very well. So did IPA (even on fluxes that resist IPA in hand cleaning). I also had great success with just water, when using ChipQuik’s water-washable no-clean flux (SMD4300 gel, and the equivalent solder wire). Of course, both for that and for SWAS, you need to have deionized water for a final rinse. (I’m lucky to have a DI water faucet at work.)

[2X]

I tried with hand cleaning the Flux Remover COSOLV175-1.0 but I am not impressed. I would say it dissolve flux residues 30% more easier than Isopropyl Alcohol and has smell were that is mildly affordable (with my nose at least). I use it only in special cases that I have plenty flux over hot air desoldering. I will continue to be fun of Isopropyl Alcohol.

I’m not sure I’m understanding — if it cleans 30% better than IPA, why are you unsatisfied with it?

Also, I found that this make a very good cleaning with hands and with ultrasound cleaners (not only in flux residues buy and in corrosion – I haven’t tried yet).

SWAS Safewash Super
https://electrolube.com/product/swas-safewash-super/

At 4:24 - SWAS Safewash Super

I just got an ultrasonic cleaner at work, and I found SWAS to work very well. So did IPA (even on fluxes that resist IPA in hand cleaning). I also had great success with just water, when using ChipQuik’s water-washable no-clean flux (SMD4300 gel, and the equivalent solder wire). Of course, both for that and for SWAS, you need to have deionized water for a final rinse. (I’m lucky to have a DI water faucet at work.)

I don't like the smell of the COSOLV175-1.0 and also the IPA is more cheaper (at least here in my place). Maybe over the years I am totally addicted in IPA.

[2X]

"(SMD4300 gel, and the equivalent solder wire)"
Do you have a part number of the solder wire?

So did IPA (even on fluxes that resist IPA in hand cleaning)
Yes I have seen it... the IPA with ultrasonic cleaner is far away more powerful at flux residues (I don't know if makes good job on PCB corrosion).
Thanks for your reply.

[tooki]

"(SMD4300 gel, and the equivalent solder wire)"
Do you have a part number of the solder wire?

https://www.chipquik.com/store/index.php?cPath=600_610_611 is the product category. I have the SMDSW.020 (I forget which size roll).

[2X]

"(SMD4300 gel, and the equivalent solder wire)"
Do you have a part number of the solder wire?

https://www.chipquik.com/store/index.php?cPath=600_610_611 is the product category. I have the SMDSW.020 (I forget which size roll).

I always be a bit of hesitate on solders and fluxes that cleaned with water but because everything you have said me is guarantee I will give a try. If you compared the Kester "24-6337-0010" with the chipquik water-washable no-clean how you will find the flow? The Kester for all the solders that I have used is on top of my list.

P.S. Thanks for the link.

[tooki]

I always be a bit of hesitate on solders and fluxes that cleaned with water but because everything you have said me is guarantee I will give a try.

As I told you via private message, even with the “water washable no-clean” (which expressly state the residues are safe to leave on), I didn’t feel comfortable trying them until I had access to an ultrasonic cleaner and unlimited deionized water. I certainly did not “guarantee” anything. Only a chemical analysis for ionic residues, and/or long-term aging results, would give us that.

If you compared the Kester "24-6337-0010" with the chipquik water-washable no-clean how you will find the flow? The Kester for all the solders that I have used is on top of my list.

On fresh components/boards with little to no oxidation, both work well.

On more oxidized surfaces, the Kester 44 is decidedly better.

[JJ_023]

I am no expert but this particular product I use for all of my needs.  I know the datasheet is primarily for SMD and Wave but it works just fine for regular soldering.

MG Chemicals - 8351-1L No Clean Flux

https://www.mgchemicals.com/downloads/tds/tds-8351.pdf