Type of solder to use: important for a hobbyist?

[Dundarave]

I was a full-time electronic service tech from about 1972 to 1992, doing discrete component repairs on audio products in the pre-RoHS days, and I've still got tons (well, a couple of pounds, anyway) of Kester's finest eutectic 63/37 tin/lead rosin-core solder left over that makes soldering a joy, compared to the newer lead-free compounds.

So I'm back into electronics now after 25 years, and luxuriating in the miracles that have occurred in the interim ($450 200M DSOs!  $50 T12-accurate soldering stations that heat up in seconds!  4 decimal place voltage standards that cost $20!  60MHz Arb. Wave Generators for $120!  All unheard of in my day!) and was wondering if I need to change my ways with respect to my now-prehistoric soldering practices given the presence of lead-free solder, fume extraction fans, and the general sense that lead solder & rosin fumes = certain death.

I had imagined that the leaded vs lead-free solder question might be one of those forum religious issues, but couldn't seem to find any threads on it (perhaps the subject has been simply burned out by exhaustion). 

So, my question:  given that I've survived over 20 years of lungfuls of lead & rosin fumes over a bench (with a cigarette hanging out of my mouth in those days, to boot) is there really any compelling reason or need for me to toss my tin/lead solder out and embrace the lead-free way?  I'm aware of the higher temp needed for lead-free, and its propensity for tin whiskers, both of which suggest that for me, leaded is the way to go, assuming everything else is equal.

What do other people use?  Does "everyone" use lead-free now?  Is it, like, 50-50 some do, some don't?  Do just the old-timers stick with leaded & the Gen X team go with lead-free?  Just trying to get a handle on the situation...

Thanks!
 

[mariush]

I'm using 63/37 with 2% no-clean flux

I don't see any reason to use lead free as a hobbyist.

All I can say to a hobbyist: stay away from solders with water soluble fluxes - you may think it means "you can use water to clean the flux residue" but it's a bit more complicated than that, and it's better to just avoid them.
Also, "organic" or "green" fluxes are often more toxic, worse for your lungs...plain RA or RMA fluxes or no-clean are best choice solders

Oh yeah, and I can't stress how much having liquid flux helps you... it's a must purchase for every hobbyist.

[Ian.M]

The *ONLY* reasons a hobbyist should use Pb-free solder is repair and other rework on post-ROHS equipment (to avoid the mixed alloy solder joint reliability issues), or if you are making anything for sale.    Pb-free and its fluxes are harder on your soldering tools, stress components more, and, without exacting process controls, result in lower reliability joints.

It doesn't take much to keep a spare bit for ROHS compliant work, + a spare bronze wool tip cleaner if you use that type, and a minimal supply of Pb-free solder.  Nothing else that a hobbyist uses is likely to introduce enough cross-contamination to matter.

The health risks of SnPb solder are minimal if one follows the usual safety practices to minimise ingestion of it, and the environmental consequences are also minimal as long as you keep as much of it as possible out of the domestic waste stream as heavy metal contamination of acid leechate from land-fill is a significant issue.

[rrinker]

 A eutectic solder is easier to use, and makes nicer joints.

 I still use 63/37. The danger factor has been well overblown. Don't eat it. Wash your hands after using it. Basic common sense. Had darn near the same argument recently on a model railroad forum about using chunks of lead to add weight to the cars. Someone wanted to know if it was safer to paint/seal the lead after installing it - well, if the temperature is high enough that lead vapors are being given off, there also would be nothing left of your plastic models.

I've never done production levels of soldering, just hobbyist, but always with leaded solder and I'm perfectly normal 

[Buriedcode]

Whilst leaded solder is more forgiving and generally "easier" to use for hobbyists - if you use half decent lead free, say SAC305 which is near eutectic, a temperature controlled iron set at 315-350C and flux, it really isn't much different.

A lot of the hate lead free got from hobbyists came from early cheap lead free solder with poor flux leading to dry brittle joints.  That and too low a tip temperature (just upping the temperature by 30C doesn't cut it).  I can't lie, I can tell the difference, and standard flux cored 67/37 is very hard to "get wrong", but with the above conditions is almost as easy with lead free.  Pretty difficult to screw up.

[darrellg]

63/37 Kester 44 is my choice.

[Ian.M]

If you are working with RF or electrostatic screening  Sn60/Pb40 is slightly easier to work with as its just far enough from the eutectic  Sn63/Pb37 to give a 5 °C melting point range which is helpful if you are doing long seams in sheet metal work.  If you can find it at an affordable price Sn62/Pb37/Cu1 vastly extends tip life of bare copper tips or ones with thin easily scratched iron plating, and also makes soldering very fine copper wires much easier as it vastly reduces the molten solder's tendency to dissolve copper.  There's also Sn62/Pb36/Ag2 which doesn't dissolve the silver  from silver plated ceramic terminals (some RF stuff, test equipment and some SMD capacitors).

*BEWARE* of cheap Chinese 60/40 solder that's actually Sn40/Pb60 (or some random alloy close to that because its made with reclaimed but not purified metals).   Its absolutely cruddy for electronics and light electrical use.  Its legitimate use is wiped joints in lead pipes (non-potable water), repairing old car radiators etc. where its wide plastic range is an asset.   As long as recycled Lead is significantly cheaper than recycled Tin (e.g. scrapped batteries), some unscrupulous sellers will be packaging it as 'electronics grade'.  Currently there isn't a lot of difference between spot Tin and Lead prices so there's less of it around masquerading as the good stuff.

[Domagoj T]

If you are working with RF or electrostatic screening  Sn60/Pb40 is slightly easier to work with as its just far enough from the eutectic  Sn63/Pb37 to give a 5 °C melting point range which is helpful if you are doing long seams in sheet metal work.

Could you please elaborate on this? Why is partial melting/solidifying beneficial in this scenario?

[Ian.M]

As you heat it up you get a tiny bit of warning that the joint is softening before it all drops apart as there is a slight mushy feel when you are rubbing the end of the solder wire into the joint just before it starts melting freely.  Depending on the work, if a 100W soldering gun isn't man enough for the job I typically preheat the metalwork with a butane pencil torch and that little bit of warning is essential if you need to avoid blobs of solder dropping or running inside the screening can.

[Domagoj T]

I get it.
Thanks.

[tautech]

So, my question:  given that I've survived over 20 years of lungfuls of lead & rosin fumes over a bench (with a cigarette hanging out of my mouth in those days, to boot) is there really any compelling reason or need for me to toss my tin/lead solder out and embrace the lead-free way?

Certainly not. Stick with leaded solder.

I'm aware of the higher temp needed for lead-free, and its propensity for tin whiskers, both of which suggest that for me, leaded is the way to go, assuming everything else is equal.

What do other people use?  Does "everyone" use lead-free now?  Is it, like, 50-50 some do, some don't?  Do just the old-timers stick with leaded & the Gen X team go with lead-free?  Just trying to get a handle on the situation...

Well you can give that Pb free muck a go and no doubt you'll encounter it when doing rework on modern gear....personally I hate the Pb free muck and dilute it with ordinary solder to lower its melting temp then suck it off.
Do get some flux though, paste seems the most popular but the flux pens mostly work OK.

[mrpackethead]

Whilst leaded solder is more forgiving and generally "easier" to use for hobbyists - if you use half decent lead free, say SAC305 which is near eutectic, a temperature controlled iron set at 315-350C and flux, it really isn't much different.

A lot of the hate lead free got from hobbyists came from early cheap lead free solder with poor flux leading to dry brittle joints.  That and too low a tip temperature (just upping the temperature by 30C doesn't cut it).  I can't lie, I can tell the difference, and standard flux cored 67/37 is very hard to "get wrong", but with the above conditions is almost as easy with lead free.  Pretty difficult to screw up.

You speak much truth.   A good SAC305 solder is pretty easy to use and its reliable.   I dont' do soldering as hobby, it is work, so i have to use Pb Free for compliance reasons.    Most of what i do is surface mount, and to be perfectly honest i'm yet to find a solder paste that works better for MY use cases than Henkel GC10, which is lead free.

[Macbeth]

... I've still got tons (well, a couple of pounds, anyway) of Kester's finest eutectic 63/37 tin/lead rosin-core solder left over that makes soldering a joy, compared to the newer lead-free compounds.

... is there really any compelling reason or need for me to toss my tin/lead solder out and embrace the lead-free way? 

Considering the RoHS was purported to be to reduce the amount of toxins such as lead being dumped and concentrated in environmental disaster zones, disposing of your existing stock seems extremely counterproductive to the spirit of the regulations.

[jmelson]

  A good SAC305 solder is pretty easy to use and its reliable.   I dont' do soldering as hobby, it is work, so i have to use Pb Free for compliance reasons.    Most of what i do is surface mount, and to be perfectly honest i'm yet to find a solder paste that works better for MY use cases than Henkel GC10, which is lead free.

Yes, I finally got some GC10 (sold by Loctite in the US, it was hard to get at one time a few years ago)  and it is excellent!  I've started using it in places where I would have used SnPb because the soldering is SO good!  I suspect the magic is in the flux.  But, they may have some trace elements added to the solder that enhance wetting.  But, it sure works well.

Jon

[Dundarave]

Thanks everyone for all the info and advice...  And yes, I think I'll add liquid flux to my list of amazing advances in electronics: We weren't using that 30 years ago either.  Great stuff.

Considering the RoHS was purported to be to reduce the amount of toxins such as lead being dumped and concentrated in environmental disaster zones, disposing of your existing stock seems extremely counterproductive to the spirit of the regulations.

So it looks like instead of going lead-free, I'll be disposing of my stockpile of leaded solder by spreading it around, one solder connection at a time...   

Thanks again.   

[Doctorandus_P]

I can confirm all of the above.

I jumped onto lead free soldering because I disliked the idea of using lead even before RoSH, but I could not even finish the first 100g roll of lead-free solder. It is a nuicanse to work with as a hobbyists.

Extra Flux is mandatory when working with smd components.
As my eyes are aging with the rest of me I recently bought an Amscope 7x-45x stereo microscope. This wonderfull piece of equipment makes soldering small SMD stuff a breeze.
Instead of a 0.5x Barlow lens I would have prefered a 0.7x lens though, but those are EUR25 as spare, so I will probably buy one.
My desk is too high for a 0.5x Barlow lens and my chair too low, so I have to sit very straight and stretch my neck / back to reach the oculair with my eyes. A bit uncomfortable, but not straining, some folks might say it is a "healthy" position.

When you are working with Lead-Free solder you have to look out for Lead contamination.
1% of lead contamination can mess with the lead free alloy and you can loose upto 90% of mechanical strength, and solder isn't that strong to begin with.

The other way around is not so critical. Whether your're soldering with 50/50 or 30/70 may influence the ease of soldering, but not the strength of the final joint.

Nowaday's "low temp" solder is also becoming more popular, and often used for repairing high density circuits such as those portable super computers of the last 15 years, which are somtimes called "phones".
I have no Idea what happens if those low temp bismuth based alloys get in contact with lead.

In my youth the Cray-I seemed to be the most wonderfull super computer ever in existance, probably because it was at that time
https://en.wikipedia.org/wiki/Cray-1
The Iconic form of the Cray 1 is also still being recognized by many (even not so computer savvy) people.
An average phone will outperform it by a factor of 20 or more, and at a fraction of the power consumption

Happy Soldering.

[mrpackethead]

I can confirm all of the above.

I jumped onto lead free soldering because I disliked the idea of using lead even before RoSH, but I could not even finish the first 100g roll of lead-free solder. It is a nuicanse to work with as a hobbyists.

What kind of solder where you using.   I regulary use SAC305 ( henkel ) with a Hakko FX-951 set at 365C and it is really no more hassle to work with than 60/40.

Extra Flux is mandatory when working with smd components.

I find that the flux ( 5 core ) that is embedded in the solder i use is normally sufficent.

[Domagoj T]

When you are working with Lead-Free solder you have to look out for Lead contamination.
1% of lead contamination can mess with the lead free alloy and you can loose upto 90% of mechanical strength, and solder isn't that strong to begin with.

Really? It's that crucial? I usually suck off the original stuff and reapply the leaded, but never paid too much attention to it. You learn something every day.

[Electro Detective]

I've gone over lead free solder after sucking it out, isohol clean up, refresh with standard lead solder, and clean up

Never a problem, shiny and 'tough as nails' joint

I must be doing something wrong to get it right 

[wernerj]

Really? It's that crucial? I usually suck off the original stuff and reapply the leaded, but never paid too much attention to it. You learn something every day.

Especially important to keep the lead out if you ever work with the low-temp solder (Sn42/Bi57.6/Ag0.4 for example), I've been told that lead wreaks absolute havoc with the melting point on those. As the melting point is already a very low 138C this apparently gets lowered even further by having even small amounts of lead present. I use low-temp solder paste for SMD prototyping as it is a lot easier to move stuff around, but these days lead-free "high-temp" paste is almost as simple. Getting the reflow profiles dialed in is a bit more challenging though - plastic connector bodies tend to have their surface finish ruined when running too hot. :/

I still also have some spools of SnPb in a drawer somewhere but haven't touched them in something like 10 years.

Most importantly though, as already mentioned above - liquid (or gel rather) flux _will_ make your live a lot easier!

[Ian.M]

When you are working with Lead-Free solder you have to look out for Lead contamination.
1% of lead contamination can mess with the lead free alloy and you can loose upto 90% of mechanical strength, and solder isn't that strong to begin with.

Really? It's that crucial? I usually suck off the original stuff and reapply the leaded, but never paid too much attention to it. You learn something every day.

I've gone over lead free solder after sucking it out, isohol clean up, refresh with standard lead solder, and clean up

Never a problem, shiny and 'tough as nails' joint

I must be doing something wrong to get it right 

SnPb tolerates a little excess tin far far better than Pb-free tolerates traces of lead.  Therefore reworking Pb-free to SnPb has no technical issues provided you suck or wick off as much as possible of the old alloy.   Its going the other way (reworking a SnPb board with Pb-free) that's the potential nightmare that Doctorandus_P mentioned.

[Doctorandus_P]

I wanted to find some references to strengthen my claim, and then I stumbled into the topic of "gold embrittlement". with Lead-Free soldering.

In the link / pdf below a connector which looks nicely soldered with a big surface area and good fillets on the sides but it did not have enough strength to survie some (de) mating cycles.

http://www.circuitinsight.com/pdf/solder_joint_embrittlement_mechanisms_solutions_standards_ipc.pdf

And plenty more to read:
https://duckduckgo.com/html?q=lead+free+solder+embrittlement
https://duckduckgo.com/html?q=lead+contamination+solder+strength

[tkamiya]

My history is just like yours.

I used and still use the usual lead-tin solder.  At hobby level, I am not exposed to whole a lot of fumes. 

[jazper]

Flux Flux flux.

If you're doing smd then make sure you get a half decent (Loctite/multicore, kester, electrolube) flux. I use electrolube flux pens and they are the business.

63/37 solder (kester) is my second favourite solder by far.

My favourite is actually the 2% silver 62/36/2 - Kester branded also.

63/37 is pretty good in comparison, but doesn't have the edge...

I have some lead free Edsyn solder, the problem I have with it is it solidifies cloudy, which means I find it more difficult to see if I've got a good joint or not.

[mariush]

You probably mean 63/37  ... and probably 62/36/2 for the silver solder.

I wouldn't trust eBay with solders, unless the seller has a very good reputation with lots of history in selling such stuff. Your link seems good.  That solder is old stock (solder in picture is dated 2015) but it's not like the solder goes bad in a few years)
Digikey and other distributors stock these solders so it's not a problem buying a spool once a year (or more often depending how much you solder) ... though Digikey's prices are kinda big, like 60-80$ for equivalent of that 36$ eBay solder.
63/37 solders are about the same price as that listing, ex around 35$ for Multicore no-clean 63/37  500g spool.