i'm switching to lead-free and want soldering advice

[digger]

i've been soldering with eutectic SnPb for decades without issue, but i treated myself to a new soldering station (aixun T420D) and decided to switch to LF to reduce the amount of hazardous residues floating around. as much as i would like to be convinced that Pb is fine for hobbyist use, please don't bother. i want to give LF a fair chance.

equipment:

jbc clone station:
https://www.aixuntech.com/product/t420d-200w-dual-channel-electronics-soldering-station-with-t245-handle/

genuine jbc C245 carts:
C245056 bevel 3.5 – heavy duty use (i mostly picked this as my heavy duty option because i found it on sale)
C245963 bent chisel 1.8x0.8 – general use, bigger jobs, tough access
C245906 chisel 1.2x0.7 – general use, smaller jobs

materials:

i researched consumables and settled on SAC305 (Sn96.5Ag3.0Cu0.5). SAC405 also looked good – slightly stronger due to more silver – but i couldn't really find it for sale. i also saw Sn99.3Cu0.7, but it didn't seem to offer any benefit aside from being cheaper, and it might in fact be worse?

solder wire: i went with chipquick because it was the only well-reviewed wire i found sold in smaller (sub-1lb) quantities.
chipquick SAC305 .031" (SMDSWLF.031 4OZ)

flux: my wire has a hot-water-washable REL0 core. instead of getting the equivalent chipquick tacky flux, i decided to try stirri's equivalent because it was well reviewed:
STiRRi Hydra-UHF-TF

methods:

i cal'd the station with a K-type thermocouple against my biggest cart (C245056). it only read about 6°C low. smaller tips had a larger discrepancy due to more thermal resistance between measurement points.

observations:

i tried soldering with C245906. initial impression is not good. i can make joints, but the experience blows.

the flux smoke is more voluminous and smells way worse. i think that in addition to extraction, i need actual filtration now. my older rosin vapor smells like flux, idk. not good, but tree-like in a way. this new resin stuff smells like burning bullshit.

the solder looks significantly worse, oxidizes faster, and flows worse. i knew going into it that i would have to forfeit pretty-looking joints, but jeez.

the tip oxidizes faster, but that's to be expected at higher temps.

issues, questions:

i did some through-hole soldering. C245906, 350°C station temp (actual tip temp likely lower).

after getting over the shock of how much worse this stuff is (although still usable!), here are my actual issues.

despite fully (re)flowing the joint and applying ample additional flux, the joint's solder had a tendency to draw away towards the receding iron tip. this gives a poor joint appearance due to irregular shape. the problem got much worse with any amount of extra solder in the joint.

with SnPb, i am used to fixing this by adding a dab of flux and reflowing the joint. even if there's a bit of extra solder, the surface tension pulls it together into an attractive geometry.

with SAC305, i fixed it by repeatedly removing small amounts of solder with the iron, cleaning the tip, applying flux, reflowing, and repeating until it was ok, and even then it was sometimes not perfect.

do i need to jack up the iron temp even more? jeez

should i try different solder? different flux? please recommend specific brands and parts if possible

also, what's a good LF tip-tinner-cleaner (the solid compound that comes in a tin)?

thanks

[coppercone2]

Well I am sorry to hear you got scared of lead. The most important thing is that you probobly get a good comfortable microscope so you can study your solder joints for a long time... as with learning anything... you need feedback from your work more then anything else.


What I don't like about lead free in addition to it being generally dodgy, is that the flux is baked on harder, and you need more solvent and work to remove it (more chemical exposure from hydrocarbons and such).... you can't get away from the high temperature, so I am not so sure its that much healthier in the grand scheme of things... I kinda felt like im making a kind of trade rather then getting a improvement here.

that is a big reason why tip size and solder station matter, so you can use the lowest possible temperature with highest heat flow, so you don't cook the flux. You can really learn it if you braze with a flame, you can see how important tip size and technique is, because its directly proportional to how much heavy scrubbing you need to do lol, it can go from gently scrub with nylon to need angle grinder.

[digger]

Well I am sorry to hear you got scared of lead. The most important thing is that you probobly get a good comfortable microscope so you can study your solder joints for a long time... as with learning anything... you need feedback from your work more then anything else.


What I don't like about lead free in addition to it being generally dodgy, is that the flux is baked on harder, and you need more solvent and work to remove it (more chemical exposure from hydrocarbons and such).... you can't get away from the high temperature, so I am not so sure its that much healthier in the grand scheme of things... I kinda felt like im making a kind of trade rather then getting a improvement here.

that is a big reason why tip size and solder station matter, so you can use the lowest possible temperature with highest heat flow, so you don't cook the flux. You can really learn it if you braze with a flame, you can see how important tip size and technique is, because its directly proportional to how much heavy scrubbing you need to do lol, it can go from gently scrub with nylon to need angle grinder.

truth be told, i'm on the fence and may return to SnPb. as i said, i am determined to give LF a fair try first, though. i think with more practice (and maybe with different materials?), there is some improvement to be gained in my LF experience.

i have microscopes

alcohol vapors don't really scare me, although i will probably switch from i-PrOH to EtOH for the heck of it.

perhaps i should have tried one of the larger carts for my through-hole tests...

[nvmR]

I have tried lead free at work in conjunction with a Weller WX 2021. Terrible experience.
Solder tips would oxidize, and all joints would be cold.

Lead solder with the aliexpress special of a usb-c soldering iron would do a much better job.

[BrokenYugo]

From what I've read the "Sn100" type alloys with nickel and germanium are supposedly best for hand soldering. I haven't yet made the switch.

[coppercone2]

Ehh I don't think its great for you though. Plus the increased smoke from higher temperature and generally everything is being heated more (plastics/pcb) and probably offgassing.

IMO the higher temperature kills the process, because I noticed the universal law is that the lower the temperature, the nicer it comes out. Everything high temperature is freaking bizarre.


My best tip would be get a nitrogen shielded iron, that should reduce your cleaning requirement. I don't think your gonna get around the high temperature effects on metal oxidation with anything else. Its what you need for welding to get anywhere near clean.. and you need ALOT of gas.

[digger]

From what I've read the "Sn100" type alloys with nickel and germanium are supposedly best for hand soldering. I haven't yet made the switch.

i've heard good things. hopefully some LF evangelist will chime in with specific product recommendations.

[digger]

My best tip would be get a nitrogen shielded iron, that should reduce your cleaning requirement. I don't think your gonna get around the high temperature effects on metal oxidation with anything else. Its what you need for welding to get anywhere near clean.. and you need ALOT of gas.

well... i do have a large Ar cylinder i'm not really using atm for anything else. i guess i could fabricate or buy a shroud. it would really bulk up the iron, though...

[coppercone2]

thats just my pessemistic observation about temperature, oxidation, materials damage and advertising.

Basically I hear alot of great things about different products. My experience tells me basically heat kills and you can either cool it or get rid of oxygen. And at high temperatures neither really works, I got my parts professionally heat treated, of course even in the vacuum kiln they end up looking a little toasty.

It seems to look OK when its made in a big factory special expensive oven with tons of controls. I saw my big personal budget co worker violently throw a roll of silver bearing expensive solder / premium flux into the trash can after doing the 'financial best' for lead free on a rather expensive soldering iron lol. It remind me of the battle of Klendathu... you get the finest war plan with the most expensive equipment, with a plan for a 15 second battle and ends with a total retreat.


I took that roll and used it to solder two 0000 gauge wires into lugs for my heater. I never though I would solder a nearly 1 inch cable with 0.4mm silver solder. I packed it in with a push rod

[rich t]

A flux pen can really help...

I use: Kester 2331ZX Water Soluble Flux Pen, White

Or for no clean: Kester83-1000-0951 951 Soldering Flux Pen Low-Solids, No-Clean 10Ml

[jonpaul]

Been soldering since 1950s......

EE since 68, started the RoHS lead free early 1990s.

We found out SAC305 is costly and has downsides

Industry   migrated to SN100C after the patents expired.

We have used ~ 100 kG SN100C in SMD magentics fab, (bar stock).

See the websites like AIM, for more info on alloys.

For rework, protps and hand soldering, we use only 63/37 Eutitic allow and Ketste 44 cored wire solder.

60 /40 is next best.

We use ourMetcl SP-200 1992 designed solder stations ("SmartHeat) and Hakko 936 conventional iros.

Jon

[coppercone2]

We found out SAC305 is costly and has downsides

Jon

Soldering a big inductor with SAC305

[Phil1977]

I can highly recommend FELDER SN96.5 Ag3 Cu0.5:

https://www.felder.de/products/electronic-applications/manual-soldering-mechanical-soldering/solder-wire/loetdraht-iso-core-clear-52760520.html

It´s not cheap, but it´s the closest thing to SnPb-solder you can get. Together with a non-too-sketchy solder station between 335 and 370°C it really has good handling, it easily flows into stranded wire and other cavities and it has a very well performing flux inside.

Cheap SN99 solder really is the hell for hand soldering. But if you can get high quality stuff like mentioned, you can easily get less toxic.

PS: I don't thing nowadays fears about metallic lead are justified. As long as you solder electronics and not your kitchenware with it and especially as long as you do it occasionally and not many hours daily for business there are probably much more important things for your health than banning SnPb. But if you want to do it, then take a high quality solder and enjoy being lead-free.

[ms3071bhk]

I can recommend STANNOL FLOWTIN KS100 TSC (Sn95 Ag3,8 Cu0,7)

KS Series datasheet (german supplier homepage): https://www.schukat.com/schukat/pdf.nsf/index/687ABEF12247A190C12584C6004C995B/$file/TDS_KS-Serie_EN.pdf

The KS100 is REL0 halide free, FLUX is 3%.

I am using it with a JBC station with 320° - 340°C (but mostly: 320°), and I am getting permanent good results.
For some unknown reasons, it is not at the Stannol webpage, but as I called them, the told me: not all products are at their homepage, the article KS100 is an active article, distributors / direct customers can order this product series, and Stannol then manufactures the alloy. Made in Germany   
There seems to be permanent demand, as several dsitributors have the KS100 series in different diameters on stock.

[tooki]

From what I've read the "Sn100" type alloys with nickel and germanium are supposedly best for hand soldering. I haven't yet made the switch.

i've heard good things. hopefully some LF evangelist will chime in with specific product recommendations.

I’ve been saying for years on here that the best lead-free solder I’ve found is Felder SN100Ni+ ISO-Core Ultra-Clear. I have posted about it in many threads. (I guess you didn’t do much searching on here, since it undoubtedly would have turned up in the various threads about solder recommendations.) Unlike SAC305, which always produces slightly dull joints, it is possible to get shiny joints with the Sn100Ni+.

As others have also hinted at, it’s not just the alloy that matters, but the flux. IMHO Kester and Felder (and Elsold) are superb. ChipQuik flux core is ok, but more acrid. Stannol I find disappointing.

[agehall]

For hobbyist level work - just use lead.

I have tried LF and use it from time to time and the key for me is good flux and taking my time, allowing longer for the joint to heat up and let the solder flow.

But in the end, I just use gloves and a good fume extractor with leaded solder 99% of the time. It is much easier to get good joints and reduces my exposure to virtually nil. I probably get more lead exposure from shooting pistols a couple of times a month where I don’t use gloves when handling ammunition.

For a hobbyist, LF solder is probably more of a pain than a gain imho.

[digger]

For hobbyist level work - just use lead.

i get it. like i said, i've used Pb for decades. it's great stuff, but i want to experience the best LF has to offer in hand-soldering and give it a fair chance.

also as stated, i really don't want to turn this into a RoHS@home discussion, but suffice it to say that any reduction in exposure is probably good. i don't have a dedicated soldering workspace, and i'd rather not remember to vigorously wash my hands every time i solder or move equipment around on my desk. i just got a brand new desk/bench and brand new soldering equipment, so i'm giving LF a try before contaminating everything with Pb residue/particles.

[Psi]

I'd be more worried about selecting solder that contains flux without harmful chemicals then I'd be worried about the lead content.

[digger]

does anyone happen to know the best way to get felder in the US? i see some options on ebay (intl shipping) and amazon.de, but the (shipped) price and/or selection could be better.

I can highly recommend FELDER SN96.5 Ag3 Cu0.5:

https://www.felder.de/products/electronic-applications/manual-soldering-mechanical-soldering/solder-wire/loetdraht-iso-core-clear-52760520.html

It´s not cheap, but it´s the closest thing to SnPb-solder you can get. Together with a non-too-sketchy solder station between 335 and 370°C it really has good handling, it easily flows into stranded wire and other cavities and it has a very well performing flux inside.

have you tried Sn100Ni+?

the best lead-free solder I’ve found is Felder SN100Ni+ ISO-Core Ultra-Clear
...
IMHO Kester and Felder (and Elsold) are superb.

i see that felder's got clear (rel1), ultra-clear (rel0), and EL (rol0). have you tried clear or EL?

it's my understanding that comparing fluxes just based on RO vs RE alone is not straightforward, although superficially RE seems more high tech to me. in my very limited experience, RO smells better, lol.

anyway, i have heard that it's best to only use resin with resin and rosin with rosin. is that actually the rule of thumb for compatibility?

do you guys have favorite syringe fluxes?

i've heard very good things about stirri v3-tf rol0 flux and kinda want to try it, so i wonder if felder Sn100Ni+ in EL core is good.

Given the choice, Kester is my absolute favorite so far, but surprisingly, the fairly inexpensive Felder from Germany is my second. Their lead-free solders are available from reichelt.com at very reasonable prices.

which kester do you like? have you tried K100LD, or were you talking about Pb kester?

kester's a lot easier for me to get. i believe their headquarters is very close to me, actually.

also, if i give up and go back to Pb, what's you favorite eutectic SnPb solder?

[digger]

I'd be more worried about selecting solder that contains flux without harmful chemicals then I'd be worried about the lead content.

ok, so recommendation?

[Phil1977]

I'd be more worried about selecting solder that contains flux without harmful chemicals then I'd be worried about the lead content.

Regarding toxicity you should stay away from old-schooled tinsmith tricks. E.g. the usual rosin-content in electronics solder is not healthy to breath in, but it seems not to be too toxic. But if you mix organic flux (like rosin) with chlorine-containing chemicals like salammoniac, then the decomposition products can get extremely nasty like the infamous doxins.

For sure it´s not the only stuff to care about. But it´s a huge difference in toxicity between "maybe allergenic" to "strongly carcinogen".

have you tried SN100Ni+?

No not yet. I´m really very happy with the SAC and I got a big spool that should be sufficient for the next years. But if I come around the Sn100Ni+ I´ll happily try it. And, by the way, the shining of the SAC-joints is not that silvery like with fresh SnPb, but it´s so good that you can easily distinguish if a joint is good or "cold".

[mikeselectricstuff]

I'd be more worried about selecting solder that contains flux without harmful chemicals then I'd be worried about the lead content.

This.
IME  LF flux is way naster than anything lead is going to do to me

[digger]

This.
IME  LF flux is way naster than anything lead is going to do to me

even with good extraction+filtration? to me, that seems like the 'correct' solution to the flux vapor/smoke issue.

but if at all possible, let's focus on specific solder wire and flux recommendations

[digger]

mg chem 49500WS
https://mgchemicals.com/products/soldering-supplies/solder-wire/water-soluble-solder/

a high-purity, eutectic 99.5% tin / 0.5% copper and cobalt alloy, complemented by a water-soluble flux core
...
This solder is a great lead-free alternative to leaded solders. In general it provides better wetting, contact angle, flow and appearance than typical Sn63/Pb37 no clean solders, while still delivering excellent performance characteristics. It offers superior solder penetration into plated through-holes and surface mount interconnects. It is a suitable replacement for SAC305 solder because it forms brighter, shinier and less-grainy joints and is also less expensive.

that's a damn bold claim. what?
edit: false alarm, the flux is high activity (ORH1). i guess that's why it may have crazy performance.

-----

possibly interesting options:

i completely missed this because their website sucks, but chipquick's got CQ100Ge (Sn/Cu0.7/Ni0.05/Ge0.006):
ROL0 no-clean: https://www.chipquik.com/store/product_info.php?products_id=625002
REL0 no-clean water-washable: https://www.chipquik.com/store/product_info.php?products_id=625003
unfortunately, the only 'sample' (sub-500g) option they have seems to be solid wire:
https://www.chipquik.com/store/product_info.php?products_id=630063

--

kester K100LD
https://www.kester.com/DesktopModules/Bring2mind/DMX/API/Entries/Download?Command=Core_Download&EntryId=1252&language=en-US&PortalId=0&TabId=96
looks like they have it in multiple cores
268 rol0:  https://www.kester.com/products/product/268-flux-cored-wire
275 rol0: https://www.kester.com/products/product/275-flux-cored-wire
48 rom1: https://www.kester.com/products/product/48-flux-cored-wire

the latter two sound more forgiving than 268. just based on the descriptions, 275 makes the most sense to me. then again, 48's indicated as basically a successor to 44, and everyone loves 44.

all three feature this blurb in their datasheets:

The flux residues are non-corrosive, non-conductive, and do not require removal for most applications under normal conditions of use. IPA will not clean the residues off the surface of the circuit board after the soldering process. If removal is required, a saponifier or cleaning agent specifically designed to clean a no-clean flux is required to clean the residues. Please contact Kester Technical Support for further information.

i think it's interesting that they say iPrOH won't clean the residues.

it's also weird that 48 has this in its datasheet but is otherwise not marketed as no-clean. i wonder what's up with that.

[mikeselectricstuff]

This.
IME  LF flux is way naster than anything lead is going to do to me

even with good extraction+filtration? to me, that seems like the 'correct' solution to the flux vapor/smoke issue.

For production, extraction is good, but you don't need it for development-type use of leaded - there's already too much stuff on the bench before cluttring further with extraction.