Flux with pleasent or least odor during/after use? - Page 1
Forum section: electronics / beginners

author: OriginalDan
author_rank: Contributor
timestamp: September 01, 2022, 09:51:28 am
content: Gday, Any recommendations on flux that has the least amount of odor during/after use? or atleast has a pleasant smell during/after use?i don't have a sense of smell at all. as in i was born without it, since i just started learning to solder i pickup up a fluxpen recently and soldered away..only to completely stink the whole house out despite having a fan with tubing mounted to vent outside my window (see attached images)said flux pen is: CT-NC-DP "No-clean Flux Pen contains AIM NC264-5 flux, a resin free, halide-free, no clean flux"data sheet linkweirdly the datasheet says 12ml when the one i got is 10, also couldn't find any images of it so it's attached belowit mentions 'wave solder flux' so i guess this isn't really for general usefamily said it was a harsh chemical 'nail polish' smell, took a good hour or two to clear out.asked a mate as he has some generic tub of flux he claims his is more of a 'burning pinewood' smell.I'm mainly learning to repair older 80s/90s computers and building synthesizer projects though i do want to learn how to repair modern gear, i was practicing on junk board ICs to prepare for a SOP28 IC specifically SLC2013M to repair a 2013 smart tv. the worst i can do is kill it more right? hahahttps://youtu.be/iKDAmY9Rdagafter watching this the 'CIF F42202 Gel Flux' sounded good as SDG claims it smells like lemon?but then in this video:https://youtu.be/g0sGGiHSmjEit looks like CIF leaves some etching on the pcb and more on the copper :/also if any aussies read this is there a recommended supplier you use? as when i looked up CIF element14 had them in stock but they have a Ton of negative reviews with wrong orders sent and replacements also being wrong, months back and forth etc.does Australia have any suppliers with local stock anymore or are they all fronts for Chinese imports?I'm upgrading my ventilation to an inline fan since that "Micron T1297 Fume Extractor Desk Swing Arm" seems like they took the generic $30 desk fans and attached em to a boomarm. should've known better but even with it over the top of my work area it really doesn't pull much. i recall eevDave mentioned some of those cheap ones motors could burn out? not sure if it's the same though.any more suggestions for improving things so my family doesn't murder or banish me to the freezing garage would be much appreciated lol.maybe a small air purifier after soldering? or during?

author: wraper
author_rank: Unknown
timestamp: September 01, 2022, 10:03:20 am
content: Your fume extraction setup seems wrong. With such you likely get fumes straight into your face, and then most of them spread around, not sucked out. Optimally you want it sucked just above where you solder, not somewhere far away.

author: JohanH
author_rank: Frequent Contributor
timestamp: September 01, 2022, 10:15:47 am
content: Quote from: OriginalDan on September 01, 2022, 09:51:28 amOld PCBs can create a horrible smell when you heat up the solder (and whatever else chemicals there might be).My (little) experience with different fluxes is that they don't smell a lot, at least in a disturbing way. But some types of solder that I've tried smelled very strong and unpleasant, e.g. cheap Chinese solder (went into the bin). Some old 60/40 solder I have is kind of a neutral smell, whereas Cynel 60/40 almost has a pleasant smell, like of pine trees.

author: janoc
author_rank: Super Contributor
timestamp: September 01, 2022, 10:31:18 am
content: Quote from: JohanH on September 01, 2022, 10:15:47 amYep. I have an old laptop board I needed some parts from and there is some sort of glue or something under the components on it that when heated produces extremely nasty, literally choking fumes, similar to hydrogen chloride. That's for sure not the flux doing that.Flux fumes can be (and often are classed as) irritant but a bit of ventilation should make a short work of that in a typical DIY setting.

author: rooppoorali
author_rank: Regular Contributor
timestamp: September 01, 2022, 10:41:17 am
content: Have you tried this? The description says it is 'odorless'https://www.amazon.com/Soldering-Durability-Odorless-Moisturizing-Activity/dp/B09RHHZMX8

author: Phaseseeker
author_rank: Regular Contributor
timestamp: September 01, 2022, 11:14:16 am
content: Personally I've always liked the smell of rosin-based flux; it's probably the pine-smelling flux you are talking about. The flux pen I use currently is a SRA no. 80, I can't really describe what it smells like but it's pretty pleasant IMHO. Still, breathing in flux fumes is probably not the best for your health...

author: Ian.M
author_rank: Super Contributor
timestamp: September 01, 2022, 11:36:45 am
content: If you (or anyone nearby) notices the smell of your flux you are breathing in too high a concentration of its fumes for safety. The risks of exposure to rosin (colophony) fumes are well known: immediate irritation of mucous membranes, and long term increased risk of asthma and/or sensitization to rosin resulting in dermatitis, possibly triggered by mere contact with rosin or even resinous woods. Humanity has been burning wood and thus exposing themselves to rosin fumes for approx. 300 to 400 thousand years and we still don't tolerate high concentrations well.Non-rosin fluxes may have much more detrimental fumes, possibly even carcinogenic, even though they may be formulated for lower perceived odor. Modern health and safety standards reduces typical exposure to the point that we are unlikely to accumulate enough whole life medical data to determine whether or not they are statistically safer than rosin flux for a long time to come.TLDR: use effective fume extraction!P.s. rooppoorali's link was to unbranded Chinese 'BST-328' solder paste, claiming to be Sn63/Pb37 composition. That's not flux, though it should contain some!

author: OriginalDan
author_rank: Contributor
timestamp: September 01, 2022, 12:34:43 pm
content: Quote from: wraper on September 01, 2022, 10:03:20 amah my apologies i forgot to mention i took those images before starting soldering and since the fan is on an arm it can move, tilt and swivel but in practice even when i had it insanely close and practically covering my hands nearly blocking my view it still didn't do much, the fan itself is insanely weak.Thanks for the video link that's quite interesting.i might try a larger fume hood with the new fan setup it should be more airflow than those $300+ aliexpress filtered setupslooking at this video:https://youtu.be/JdrFsuAcm48?t=278at 4:38 I've since tracked down aTT Mixflow Inline Fan 100mmwhich was about $100aud 187 m3/h at 36 dB(A) my local hardware store bunnings had theseManrose inline fansfor $20 cheaper but only 119 m3/h at 40db(A) also looked and felt way cheaper.Ill have to update on that inline setup later as I'm waiting for more ducting and a backdraft damper to arrive, as i noticed the straight tube from the fan out the window when not in use brought a lot of cold air in.when using that fluxpen i kept turning the fan off the second i wasn't soldering which in hindsight was dumb so ill have to leave it on further but put it on hold until i can install the new inline fanQuote from: rooppoorali on September 01, 2022, 10:41:17 amthanks ill find a seller to order it, that listing doesn't ship to aus however it's onaliexpressjust no reviews but $18aud is fine i did find it onalibabawith 2pieces min order for $21.95aud so ill try that though I've never ordered from alibaba before. [edit: seems that might not be flux? see below]Quote from: Phaseseeker on September 01, 2022, 11:14:16 amsounds like it could be good but i haven't found a source to Australia, amazon doesn't ship that here on ebay its $42aud with the refill bottle $97ontheir websiteits $9usd but the cheapest shipping is $59.35usd no idea why postage is that wild but if i can find a source for a sane price ill give it a shot. thanks.Quote from: Ian.M on September 01, 2022, 11:36:45 amyeah i naively thought the fan i got would do the job if it was very close and over the work area, atleast better than those elcheapo $20-$30 ones ya see everywhere but seems its just the same garbage with a boomarm. Being a total beginner majority of the first guides/recommendations i saw was "get a pc fan to get the fumes away from ya face" or "crack a window" which isn't ideal in winter or summer which is why i went for that fan to tube to window wood mount exhaustand i tried to go cheap since I'm next to a window no point in buying one of those expensive filtered setups when it can go outside so it 'seemed' like the logical solution lol. just the ol adage 'buy cheap buy twice' bites me again.Hopefully with the added inline fan it should be enough for proper ventilation, my setup should end up similar to this video:https://youtu.be/wT3Pj8DJ8Z4?t=152even with proper ventilation i won't mind what the contents of the flux is, mainly the lingering smell. ideally it wouldn't corrode if i miss any bits after cleaning even if performance of the flux is 'okay' then id rather compromise there. i doubt ill find that trifecta of price, quality, pleasant or no smell.that's weird i looked up that BST-328 as i couldn't find reviews there's one russian youtube video:https://youtu.be/J-4y7mAeA7cthere's auto translate to english but don't even need to understand what he's saying to see it not performing well. very odd, so that's some kind of solder paste? thanks for mentioning that i almost ordered some lol.appreciate the help, if anyone else is reading keep the suggestions going, i plan to buy a few different types to figure out which will work or ideally hit that level of decent performance but also tolerable smell.ill put an update when i have the inline fan installed and try a few different types

author: janoc
author_rank: Super Contributor
timestamp: September 01, 2022, 02:09:47 pm
content: Quote from: rooppoorali on September 01, 2022, 10:41:17 amBuying a random Chinese stuff from Amazon that is "moisturizing" and for "welding" is a pretty dumb idea, IMO. Worse, what is in the crappy, mirrored photo doesn't look like a flux at all but a leaded BST-328 solder paste.Yay.

author: wraper
author_rank: Unknown
timestamp: September 01, 2022, 03:12:23 pm
content: Use a proper inline fan. This extractor unlikely to have a fan optimized for high static pressure, therefore airflow should be dropping a lot once you attach a tube. It's simply uncapable to push the air through it. At least remove that black filter foam to reduce airflow restriction.

author: tooki
author_rank: Super Contributor
timestamp: September 01, 2022, 05:22:58 pm
content: Quote from: OriginalDan on September 01, 2022, 09:51:28 amYes: ChipQuik SMD291NL (the NL is important!). Rather than smelling of burning acid, it smells like toasted hazelnuts when heated. It’s my favorite flux now. Easily purchased from Digi-Key.

author: tooki
author_rank: Super Contributor
timestamp: September 01, 2022, 05:29:37 pm
content: Quote from: rooppoorali on September 01, 2022, 10:41:17 amWhy waste someone’s time - and possibly money - recommending some Amazon trash that isn’t even the same type of product they’re looking for?

author: OriginalDan
author_rank: Contributor
timestamp: September 01, 2022, 06:31:43 pm
content: Quote from: wraper on September 01, 2022, 03:12:23 pmfor sure, i recall a pdf somewhere on this forum with proper testing showing those charcoal filters don't appear to filter anything so i don't use em.might've missed it but i mentioned before i did pickup a Mixflow Inline Fan rated for 187 m3/h 52L/s just waiting on additional fittings to arrive before installation. ill put the soldering on hold until then.Quote from: tooki on September 01, 2022, 05:22:58 pmthanks seems that specific one is mixed with solder paste although the datasheet mentioned REL0 type flux so after searching that i found 'SMD291NL-10M' which appears to be Just the flux from the same lot which sounds perfect, and yea its on digikey and mouser for $17.50ishill give that and the CIF F42202 flux a shot, ill just be sure to not use the CIF flux on anything critical that i might not be able to fully clean like under ics/smd stuff but should be fine with singlelayer basic things, not sure why SDG didn't mention it i guess it was the least aggressive out of the harsher ones? might've looked worse on camera than in person, i might just be overzealous i could invest in an ultrasonic cleaner at some point anyway if it does turn out the best.if we can find the SRA no. 80 for a sane price ill give it a shot too.also try the only rosin flux tub available from our local general electronics store jaycarhttps://www.jaycar.com.au/solder-flux-paste-56g-tub/p/NS3070though in ballarat where i am we have a wiltronics which is partnered with jaycar so they stock the same stuff with a few of their own items you can't get from jaycar. so stay tuned ill post updates when they've arrived and been tested, much appreciate the help and if you come across anymore do let me know, thanks

author: tooki
author_rank: Super Contributor
timestamp: September 01, 2022, 07:26:28 pm
content: Quote from: OriginalDan on September 01, 2022, 06:31:43 pmThey sell it as a flux alone, but they also use it as the base for (not "mixed with") solder pastes. ("Solder paste" is the result of mixing solder powder into paste/gel flux.)Quote from: OriginalDan on September 01, 2022, 06:31:43 pmGoogling "SMD291NL" finds the flux alone, the paste doesn't appear until farther down the results. On Digi-Key, searching for "SMD291NL" finds one exact match (the 5ml syringe of flux) and links to the flux category, where it has numerous matches. It's actually harder to find the solder paste based on it!Quote from: OriginalDan on September 01, 2022, 06:31:43 pmThat's what I would (and do!) buy.Quote from: OriginalDan on September 01, 2022, 06:31:43 pmSince you can't order them from the same place anyway, just try the SMD291NL first to see if you're happy with it and don't bother ordering the CIF at the same time. One thing I really like about the SMD291NL is that it's crystal clear (other than being amber-tinged), so you can still see what's going on with flux applied. The CIF is very opaque, so until you melt it, you can't see through it. I don't know how opaque the residues are once they cool off, but if other fluxes I've used are an indication, it may well go cloudy again, making proper inspection of fine joints difficult without cleaning. The SMD291NL is always transparent and makes inspection easy.Fundamentally, every no-clean flux should be either fully cleaned, or fully heated to complete soldering temperature. (The way they work is that when cold, they're inactive, then heating them to one temperature activates them, and then heating it more (to soldering temp) neutralizes it again.) SDG tested two cases (totally unheated, and totally heated) but missed a crucial case for hand soldering: partially heated. Yes, the flux that comes into direct contact with the joint for long enough is heated to neutralization, but a lot of it gets heated enough to activate it, but then flows away and doesn't get hot enough to neutralize it, leaving residues behind that are still active! In reflow soldering, the whole board gets baked, so every bit of flux is heated enough to neutralize it. But in hand soldering, clean it up thoroughly.Quote from: OriginalDan on September 01, 2022, 06:31:43 pmThat's the RA flux from Caig. Digi-Key sells that in tubs (RSF-R80-2) and syringes (RSF-R80-8G), as well as Caig's RMA no-clean flux, also in tubs (RSF-R39-2) and syringes (RSF-R39-8G).

author: macboy
author_rank: Super Contributor
timestamp: September 02, 2022, 02:27:55 pm
content: Since you are venting that fan to the outside, remove the charcoal filters. They are intended to clean the smoke from the air when it is simply blowing through the fan, but they probably don't actually do much other than restrict airflow. If the fan is still weak, then replace it or increase the voltage to it (if it is DC). I have a Pace Evac 105 fume extractor which I got from a surplus/recycling shop for next to nothing. It works great. It pulls a LOT of air through, as much as or more than a shop vacuum, but it is relatively quiet. It will pull in the fumes from at least several inches away, horizontally. I use this in combination with a Weller WFE2P which is a vacuum pump which connects to a tip-mounted fume extractor (google AC-FX1). Needless to say, I don't breath many fumes any longer. I used to enjoy soldering but hate how my lungs felt for the rest of the day; now I can just enjoy it. I really lucked out with those purchases (and my entire Metcal soldering/desoldering system!) at that recycler.I'd suggest trying a rosin based flux. Rosin based flux smells like pine trees since it is made from pine sap. They harvest the sap to make Turpentine (from the liquid part) and the solid left over is called rosin. Manufacturers refine this, add some stuff, make it a paste/gel/liquid, and call it rosin flux. I have made a homemade liquid flux from solid rosin crushed into powder, mixed about with 99% IPA (2 parts rosin 1 part IPA), left to sit for a few days. Yes, days, it will dissolve slowly but completely. Then it is thinned as desired with IPA; I like it thicker. I put it into an eye-dropper bottle. It works well, and smells strongly of pine. Mostly though I use MG Chemicals 835 liquid rosin flux. It also smells of pine, but more mildly I suppose. I hardly notice (due to fume extraction above).Quote from: tooki on September 01, 2022, 07:26:28 pmThis is excellent advice worth repeating, so I did. Thank you.I will add that rosin becomes active only when heated, but does not become inactive with more heat. It becomes inactive again when it cools down. For this reason, most rosin (R) or midly activated rosin (RMA) fluxes can be left on the board without cleaning, even with hand-soldering. Always check the datasheet for the flux you want to use, not all are equal in this regard! The main reason to clean rosin flux is that it leaves an ugly, hard, crusty brown/amber residue. After soldering an entire board of components, it can look terrible. Very harsh environments (very humid, hot, etc.) can also compel thorough cleaning.I picked up a few of those little 5 ml tubes of the ChipQuik SMD291NL to try out. It works well, but I find that it becomes inactive very quickly. This is a frustrating combination of being able to inspect the joints under the microscope through the crystal clear flux residue (good), but then being unable to reflow the bad joint you just found, because the flux isn't active (bad)! So I end up adding more to that spot. Oh well, it's a minor thing. Far worse is the MG Chemicals Rosin paste flux I have (#8342 I think). This stuff worksamazinglywell, it is just beautiful, BUT the residues areforever highly conductiveand can't be fully cleaned from under SMD components. I had a %*&# of a time with a board where I replaced a TSOP DDR RAM chip and couldn't figure out why it would boot sometimes, sometimes not, and when it did boot it would crash... it was this flux residue cross-conducting signals. After removing the RAM chip, and inspecting the board, there was visible damage to soldermask from this effect! luckily traces were intact. I cleaned very throughly (removing several components around the area, as the flux had creeped while working), and re-assembled with the ChipQuik. That worked fine, even if I had to re-apply when my hands were slower than the flux. I don't know what that tub of MG 8342 is good for... you can't even tin wires with it (even though it works like a dream doing it), because it remains active and will likely destroy the strands over time.Sigh. Soldering is complicated these days. When I was 15, it was simple. I had a Radio Shack fire stick, a roll of Kester 44 60/40, young lungs, and all was good.

author: Phaseseeker
author_rank: Regular Contributor
timestamp: September 02, 2022, 03:15:39 pm
content: Quote from: macboyYeah, same with the 8341 "no clean" MG stuff, it works well but I've destroyed a board with it because it corroded all the vias under a QFP. I didn't know about heating ALL the flux to soldering temperature, but still, one has got to be careful with the stuff.