Which is better soldering wire (lead-free or leaded)

[Krunky]

Hi!

I want to know which soldering wire is better (which better looks on end product). Lead-free or leaded.

I recently bought Weller WD 1000 soldering station and lead-free soldering wire (Weller WSW SAC M1 Sn3.0Ag0.5Cu 100 g 0.5 mm T0051388299). Now because I am soldering something for school project that is graded I need to know which solder to use for better looking soldering joints.

*Arguments why which are welcome.
Thank you for your help!

[rstofer]

Leaded solder will probably look better BUT...  The world is in a panic over lead and particularly lead in electronics.  I wouldn't use leaded solder in any project that was going to leave my little work area.

In any event, the key to a good looking solder joint is flux.  If the joints didn't look good enough with just the flux in the core of the solder, I might add a little paste flux.

[plazma]

Leaded is way better and easier to use

[uncle_bob]

Hi

How much do you want to go to jail? What are the laws about lead where you live? What will they be next week?

There is no argument about which one works better. The whole issue revolves around the sort of troubles you will get into using lead based solder. There is the minor issue of poisoning yourself and your family with lead, it's usually slow enough that it's not a big deal if you take all the proper precautions.

Bob

[Krunky]

Hi

How much do you want to go to jail? What are the laws about lead where you live? What will they be next week?

There is no argument about which one works better. The whole issue revolves around the sort of troubles you will get into using lead based solder. There is the minor issue of poisoning yourself and your family with lead, it's usually slow enough that it's not a big deal if you take all the proper precautions.

Bob

You can buy leaded soldering wire in every electrical store. Teachers are grading how smooth and good looking the joints are (some points for that). I am just asking for your advice. And LAWS about this in Slovenia arent changing soon.

But thanks for your reply 

[Andy Watson]

Teachers are grading how smooth and good looking the joints are (some points for that).

In that case, leaded is the way to go. Unless they are going to dock points for not using non-leaded.

[stmdude]

There is no argument about which one works better. The whole issue revolves around the sort of troubles you will get into using lead based solder.

I thought the whole RoHS debacle only applies to products that are being sold?  I.e, not prototypes and for-personal-use things?  Then again, I'm no expert on the subject.

And LAWS about this in Slovenia arent changing soon.

Probably not, as RoHS already is a mandate in your country as well (welcome to the European Union!).

But, to answer your question. I'm in the EU, so I'm bound by the same laws as you, and I use leaded solder exclusively for prototypes and stuff I do at home.  For the products we make at my company, it's lead-free all the way.

[madires]

Leaded solder is totally legal for DIY and hobby usage in the EU.

pros:
- lower melting point
- easier to spot bad joints
- no tin whiskers
- cheaper
- 60/40, no worries about different alloys with different melting points as with lead-free solder (Cu/Ag)

cons:
- contains lead

[Krunky]

There is no argument about which one works better. The whole issue revolves around the sort of troubles you will get into using lead based solder.

I thought the whole RoHS debacle only applies to products that are being sold?  I.e, not prototypes and for-personal-use things?  Then again, I'm no expert on the subject.

And LAWS about this in Slovenia arent changing soon.

Probably not, as RoHS already is a mandate in your country as well (welcome to the European Union!).

But, to answer your question. I'm in the EU, so I'm bound by the same laws as you, and I use leaded solder exclusively for prototypes and stuff I do at home.  For the products we make at my company, it's lead-free all the way.

Well I am in school so I dont have a company. But consider that lead is not good. You probably already saw pieces of electronics dumped in the forests,... This is not good for our enviroment. So that you are using lead-free soldering in your company is a very good thing (if you advertise that you use lead-free solder to help the enviroment you probably will get more ECO people to buy from you. I will ask my teacher if it will be OK to use lead-free soldering wire (because he is so "dumb" that he orders 2$ soldering wire from AliExpress (at least is has 2% flux and its 1mm [for our pads waaay to big diameter] and then we use that (unless you got your own).

[janoc]

Hi

How much do you want to go to jail? What are the laws about lead where you live? What will they be next week?

There is no argument about which one works better. The whole issue revolves around the sort of troubles you will get into using lead based solder. There is the minor issue of poisoning yourself and your family with lead, it's usually slow enough that it's not a big deal if you take all the proper precautions.

Bob

Nobody is going to send you to jail for using leaded solder 

The only issue you may have is that you may not be able to sell your products to places where lead-free is required - e.g. Europe (RoHS) and you may be violating workplace health regulations about heavy metal exposure in some cases if not ensuring proper ventilation/filtering. Both will at best get you a fine.

BTW, the chances of lead poisoning through soldering are very minuscule, even if you don't wash your hands after handling the leaded solder. Not that I would recommend doing that, though.

If you are afraid of lead poisoning, you should rather check your water pipes - in many places the water still passes through lead pipes on the way to your glass and that gives you a much larger (and sustained!) dose of lead than soldering.

Leaded solder is banned because lead accumulates in the environment over time (along with cadmium, mercury and few other similar elements) from the discarded/obsolete electronics, not because your soldering could poison someone.

Certainly not an issue for an average hobbyist.

Now regarding the OP's question - leaded gives you nicer looking "shiny" joints, but if the teacher is grading only that, they need to be educated. I would use the lead-free solder you have and then explain that I am environment-conscious - good luck to them trying to penalize me for "worse" looking joints over that!

[wraper]

Somewhere on the forum there was a discussion about the lead free solder. The thing is, it appears that lead free process overall (not just dumping the garbage) have a worse impact on environment than using leaded solder.

[janoc]

Well I am in school so I dont have a company. But consider that lead is not good. You probably already saw pieces of electronics dumped in the forests,... This is not good for our enviroment.

That's true, but it is not really something you need to worry about on your scale. If you were Apple or Samsung producing 100000 pieces of some item, yes, that's a significant issue.

So that you are using lead-free soldering in your company is a very good thing (if you advertise that you use lead-free solder to help the enviroment you probably will get more ECO people to buy from you.

He certainly doesn't need to advertise it, because he doesn't have a choice - selling anything containing leaded solder is illegal in EU because of the RoHS directive which bans items containing lead and few other toxic elements. So you will be hard pressed finding any electronics still containing leaded solder today, even if sold outside of EU (it is not economical to have two production lines). The only exceptions are some safety-critical areas like airplanes, spacecraft or cars which are still allowed to use leaded solder for reliability.

I will ask my teacher if it will be OK to use lead-free soldering wire (because he is so "dumb" that he orders 2$ soldering wire from AliExpress (at least is has 2% flux and its 1mm [for our pads waaay to big diameter] and then we use that (unless you got your own).

I don't see what is "dumb" on 1mm solder from AliExpress. If the solder works (i.e. wets properly) then there is no issue with it. Yes, it is perhaps a bit thick, I wouldn't use it for surface mount work, but otherwise it is most likely perfectly fine for soldering wires or through hole parts.

Asking your teacher is a good idea, though, especially if it is an assignment.

[Kalvin]

It seems that getting leaded soldering wire in EU area is not a problem. There are lots of leaded soldering wires for sale in Digikey, Conrad and in local Finnish stores. These soldering wires are not typically used in mass production, though.

[BMack]

Leaded 12-0 over lead-free...and rightfully so. If significant talk of it becoming banned in the US starts, I'm buying hundreds of pounds of leaded solder.

[basinstreetdesign]

Yes, the RoHS rules are for commercial goods only and only in countries that have signed up for that.  As Far as I know there are no RoHS police for hobbyists.

But for for good looking results, the variety of solder that you use won't be as big an issue as residual flux left on the board. Get some flux remover and go to town with some of that and a toothbrush on the solder side of the board after assembling.  If you can find an ultrasonic cleaner loaded with flux remover at your school than that is even better.

[AlessandroAU]

If its going into a project for a client, just use lead-free to avoid any issues and be compliant with RoHS. Its the right thing to do.

If at home/non-commercial, go leaded all the way. Wash your hands, don't eat at your workbench and you will be fine.

If I were you I'd use some quality leaded solder for my class. If you use the soldering stations at class just don't mix lead/leaded free it will contaminate the soldering iron tip and make not work as well.

There are people scared of leaded solder that will happily go and accelerate bits of lead at targets over the weekend, spraying small chunks of the stuff everywhere. 

[DimitriP]

I want to know which soldering wire is better (which better looks on end product). Lead-free or leaded.

Here is what I would do^*:
Stick a bunch of wires though a ouple or a section of a prototyping board.

Solder them to the pads using one type of solder. Mark it leaded or lead free on the "compenent side" and put it away.
The next day solder them using the other solder. Mark it leaded or lead free on the "compenent side" and put it away too.
Let a couple of days go by and then compare them ... comparing ...please wait....


^* I'm happy with leaded solder so I have no real interest in finding out

[Ian.M]

If its going into a project for a client, just use lead-free to avoid any issues and be compliant with RoHS. Its the right thing to do.

Unless the client's project falls under a RoHS exemption, and the client specifies Sn/Pb.  Also, repair work should user the same type of solder as the original, so if you are working on pre-2006 equipment, there is a high probability that you should be using Sn/Pb.

If I were you I'd use some quality leaded solder for my class. If you use the soldering stations at class just don't mix lead/leaded free it will contaminate the soldering iron tip and make not work as well.

This isn't 'kosher' for production, or ultra-high reliability work when you must be absolutely certain there is no contamination, but in general for all except the most sensitive alloys, if you tin the bit and wipe it thoroughly, repeating three times, you can get the residual contamination with the wrong alloy down to such a low level that it will have absolutely no effect on the joint and if you were careful with the cleaning process and are using high quality Pb-free solder, it will even meet the legal limits.

[IanB]

Even with tin/lead solder the quality varies, such that with some solder wire you will get nice shiny joints and with others you will get dull joints. All solder wire is not the same, so test it and select carefully.

[Krunky]

I will ask my teacher if it will be OK to use lead-free soldering wire (because he is so "dumb" that he orders 2$ soldering wire from AliExpress (at least is has 2% flux and its 1mm [for our pads waaay to big diameter] and then we use that (unless you got your own).

I don't see what is "dumb" on 1mm solder from AliExpress. If the solder works (i.e. wets properly) then there is no issue with it. Yes, it is perhaps a bit thick, I wouldn't use it for surface mount work, but otherwise it is most likely perfectly fine for soldering wires or through hole parts.

Asking your teacher is a good idea, though, especially if it is an assignment.


----------
Well we make our boards with LPKF (Prototype board maker, CNC). The pad is 1,5mm in diameter (inside of the pad there is 1mm hole). So this means that we have only 0,5mm of pad with copper on it. The board is also printed that it just isolates (cuts 3mm) on each side of the trace. So that it doesn't make a contact between (we use this because we dont have time to wait for perfectly cut 30 boards (50x50 mm). For this I use 0,3mm soldering wire. No wonder Im the only one with A (grade; 5). If a pad was

[mazurov]

"Lead free" is too lose: there is SAC305 that everyone seems to hate and there is SnBi with melting point 40C below that of typical leaded alloy(63/37). SAC305 requires more skill; SnBi is popular in Japan and surrounding countries but hard to find outside of Asia. I use SnBi to solder power parts to copper heatsinks - works much better than Arctic Silver.

Leaded solder requires less skill to produce working joints but also calls for good hygiene. Wash your hands immediately after leaving the bench and each time before picking your nose, scratching  your eye or touching your penis (yes, you need to wash hands before going to the bathroom if male). Lead in any form is also undesirable where small children are present. Me, I solder with lead-free since before the RoHS directive came into being.  I suggest learning  to solder with SAC305 - after you succeed switching to leaded will be a piece of cake.   

[starphot]

  The specifications have changed for leaded solder. The manufacturers of leaded solder must use purer lead (Pb) in the solder. In the past, the Pb content had trace amounts of cadmium in it and they had the California health warning label on this. This contributed to the nerve damage numbness in both of my hands toward the end of my career. That took 10 years plus an unexpected side effect of medication for something else to correct the problem and for all of the embedded micro metal flakes to emerge from the fingers and palms. I was quite aggressive in the repairs and both hands got jabbed by the tiny chisel ends of the through-hole leads in the older style boards. I was one the company's regional "Top Guns".
  Kids, stay away from the Pb solder if you can! I had no problems with the non-Pb solders in electronics or for sweating copper pipes.

Joe

[jitter]

RoHS is about a lot more than just using lead free solder. But complying with RoHS is the responsibility of the company that sells a product, not its OEM.
We happily produce products soldered with lead containing solder if our customers ask for it. And yes, some of those customers are NOT exempt in any way from the RoHS directive and they sell their stuff all over the world, including inside the EU. How they get away with it, I don't know. But it seems like there's no one knocking on their doors telling them they can't (or rather: shouldn't) do that.

As for soldering with lead free solder, it's not that different from soldering with lead containing solder. It needs a slightly higher temperature and IMHO it is nowhere near that much more difficult as some might lead you to believe. It's just a bit different. The only thing that I find noticeably harder is desoldering, especially of through hole components mounted in fully metallised holes (like almost all boards in industrial electronics).

For looks, a shiny lead containing solder joint is the best. But the often heard remark that lead free solder joints aren't as good are turning out not to be so true in practice. So by all means get yourself some leadfree solder and experiment, and then decide what you will use.

[jayco242]

Hi,
  to answer the original question of best looking solder joints. Then practice, practice and practice is the answer. Proper technique of heat in, solder in, solder out lastly heat out. Many people make the mistake of taking the heat and solder out at the same time producing ugly and unreliable joins. Do a few practice runs on strip board before doing a final try. A flux pen and alcohol wipes to clean up are good to have. We dont expect you to have access to flux cleaner or any of the fancy stuff.
   Jason

[matkar]

In the past, the Pb content had trace amounts of cadmium in it and they had the California health warning label on this. This contributed to the nerve damage numbness in both of my hands toward the end of my career.

Interesting. I recently bought a spool of low melting temperature solder wire with 18% cadmium. I didn't know it contains Cd at the time of purchase, so I later put it in a drawer and never used it.

I use leaded solder (wire and paste) for my prototypes. Occasionally I produce and sell a few pieces as well and don't bother if they are not RoHs compliant.

I have tried using Pb free solder in the past but realized it's much harder to get a nice result.

The bottom line is you will for the rest of your life use what you've learnt to use.
It seems logical to put a bit of effort in learning to solder Pb free so you won't have to worry about all the issues mentioned in all the answers. So my advice is to use Pb free despite me using the other stuff.
Oh, and use a lot of flux. Probably this is even more important than solder itself.

[janoc]

Well we make our boards with LPKF (Prototype board maker, CNC). The pad is 1,5mm in diameter (inside of the pad there is 1mm hole). So this means that we have only 0,5mm of pad with copper on it. The board is also printed that it just isolates (cuts 3mm) on each side of the trace. So that it doesn't make a contact between (we use this because we dont have time to wait for perfectly cut 30 boards (50x50 mm). For this I use 0,3mm soldering wire. No wonder Im the only one with A (grade; 5). If a pad was

It doesn't really work like that. I can easily solder 0.5mm pin pitch TQFP part with 1mm solder wire and it will be just fine. In fact, I have been using 0.8mm for pretty much everything I do, I have bought a roll of thinner solder only recently for some really fine pitched work. It is really not about the relative size of the pad vs. solder diameter, especially not for through hole components with 0.5mm annular ring on the pad - there I find using 0.3mm pretty ridiculous and pointless. I think you should rather improve your technique there.

What the solder diameter has impact on is how precisely you can dose the solder while making the joint. If you are using thick solder, you are melting a lot of it at once and it is much easier to put too much solder on the pad, leading to "blobs" and bridges. That's why a thinner solder is much preferable in such case, because you can dose it more accurately.

[Ian.M]

With enough good flux, you can get good results with just about any normal solder except the cheap crap, full of dross and of dubious composition, made in the far east from recycled solder.   Sn/Pb or Pb-free doesn't make much difference if you have good flux, technique, the right temperature iron and bone dry oxide free pads and components, though the Sn/Pb joint generally looks prettier.     

Most of the time the diameter isn't too crucial either, though if I was doing a lot of hand-soldered SMD work, I'd probably reach for the 0.50mm solder as its easier to control the fillet size when soldering small discretes.  There's no need for finer than 1.2mm for any through hole work though.  In many cases a finer pitch solder will require you to feed it into the joint for longer, leading to overheating and possible component damage and pad detachment.

[jitter]

Oh, and use a lot of flux. Probably this is even more important than solder itself.

Sorry to say this, but with the usage of good quality flux cored solder, there's hardly any need for add on flux. Neither with Pb nor with PB-free solders.
Even in the industry, add on flux seems to be used willy nilly, but there's only the need for it on some specific hand solder jobs, like fine pitch SMD. And even then it's mainly to prevent solder bridging rather than to aid wetting.

[CJay]

Oh, and use a lot of flux. Probably this is even more important than solder itself.

Sorry to say this, but with the usage of good quality flux cored solder, there's hardly any need for add on flux. Neither with Pb nor with PB-free solders.
Even in the industry, add on flux seems to be used willy nilly, but there's only the need for it on some specific hand solder jobs, like fine pitch SMD. And even then it's mainly to prevent solder bridging rather than to aid wetting.

The only time I used 'extra' flux was in rework, those gullwing TQFP packages used to develop bad joints after a while, board flexing, bad solder process, heat, a combination of all, who knows, but applying flux and a hot air pencil while using a little downward pressure on the package worked wonders and the sound of the pins clicking down as the solder flowed was quite a pleasure.

So I agree, usually there's no need for extra flux beyond what's in the solder wire, if there is then you've got a problem with components or solder quality.

But if you can clean it off, there's no problem using extra.   

[LordHexahedron]

I personally vote lead free simply because lead is not a nice substance.
If you know how to solder it'll look fine either way.

I only use lead-free for RoHS compliance, but also due to the potential health implications of soldering with lead [I'd rather not get lead poisoning]

[macboy]

In the past, the Pb content had trace amounts of cadmium in it and they had the California health warning label on this. This contributed to the nerve damage numbness in both of my hands toward the end of my career.

Interesting. I recently bought a spool of low melting temperature solder wire with 18% cadmium. I didn't know it contains Cd at the time of purchase, so I later put it in a drawer and never used it.

I use leaded solder (wire and paste) for my prototypes. Occasionally I produce and sell a few pieces as well and don't bother if they are not RoHs compliant.

I have tried using Pb free solder in the past but realized it's much harder to get a nice result.

The bottom line is you will for the rest of your life use what you've learnt to use.
It seems logical to put a bit of effort in learning to solder Pb free so you won't have to worry about all the issues mentioned in all the answers. So my advice is to use Pb free despite me using the other stuff.
Oh, and use a lot of flux. Probably this is even more important than solder itself.

Lead-free solder is not worry free. It just has different worries. According to Weller:

Lead-free soldering produces up to 250 % more particles between 0.5 and 1.0 microns in diameter, the size that is the most dangerous to inhale. In addition to particles, solder smoke can contain isocyanates, aldehydes, and other unhealthy substances.

http://www.wellerzerosmog.com/health_risk/
I personally find that extra flux is more often needed with lead free solder, even premium name-brand SAC305 (silver bearing) stuff. Extra flux = extra smoke. Lead-free also needs higher temperatures, and although it doesn't sound like much to go from 600 to 700 F, this makes the difference between orange rosin residue and burnt brown residue. Imagine all the extra smoke produced.

[KL27x]

Lead works better.

Lead is not bad for the environment.

Lead does not significantly vaporize at soldering temps. When you get lead closer to its BOILING point than its melting point, then you can start worrying about lead poisoning from lead vapor.

Lead is highly insoluble in water. It does not transfer to your skin and into your mouth and poison you. As long as you don't let your solder corrode into lead oxide, it is not dangerous.

Flux fumes are the most dangerous part about solder.

ROHS is just another scam to employ people and stimulate the economy. Sorta like global warming. But even less scientific and more knee-jerk, heart-string, and plain dumb.

[LordHexahedron]

Lead is not bad for the environment.

Lead does not significantly vaporize at soldering temps. When you get lead closer to its BOILING point than its melting point, then you can start worrying about lead poisoning from lead vapor.

Lead is highly insoluble in water. It does not transfer to your skin and into your mouth and poison you. As long as you don't let your solder corrode into lead oxide, it is not dangerous.

the MSDS for lead disagrees.
http://www.sciencelab.com/msds.php?msdsId=9927204

Lead is extremely bad for the environment if a large amount gets into the water supply, hence why it's labeled as an environmental hazard, the flint crisis is a good recent example of this.
http://www.cnn.com/2016/01/11/health/toxic-tap-water-flint-michigan/

Lead is VERY TOXIC and should be handled with extreme care.

Flux fumes are the most dangerous part about solder.

Correct, flux fume inhalation should be avoided if possible.
This only applies to rosin flux, but since rosin flux is so much better than the synthetic flux options it's what everyone uses.

ROHS is just another scam to employ people and stimulate the economy. Sorta like global warming. But even less scientific and more knee-jerk, heart-string, and plain dumb.

[citation needed]

Here, have the RoHS limits [at the time of writing]

Lead (Pb): < 1000 ppm
Mercury (Hg): < 100 ppm
Cadmium (Cd): < 100 ppm
Hexavalent Chromium: (Cr VI) < 1000 ppm
Polybrominated Biphenyls (PBB): < 1000 ppm
Polybrominated Diphenyl Ethers (PBDE): < 1000 ppm
Bis(2-Ethylhexyl) phthalate (DEHP): < 1000 ppm
Benzyl butyl phthalate (BBP): < 1000 ppm
Dibutyl phthalate (DBP): < 1000 ppm
Diisobutyl phthalate (DIBP): < 1000 ppm

Every last substance on this list is EXTREMELY TOXIC, if you don't believe me - go put some cadmium, mercury, or hexavalent chromium in your next glass of water and drink it. Let's see how long it takes for you to change your mind.

RoHS is a safety standard to reduce the amount of toxins in products, which is good because you do not ever want to find any of these things leeching into your water supply.
Well, at least not if you actually understand what sort of damage it'd cause.
I'll leave it up to you to find the MSDS for the substances on there yourself, it should be simple enough - I already provided lead for you.

Oh, and a side note - some of those are contact poisons, merely getting them on your skin causes absorption.

[janoc]

the MSDS for lead disagrees.
http://www.sciencelab.com/msds.php?msdsId=9927204

I think nobody argues that lead is not toxic or that it is not bad for environment, but let's get things in perspective, shall we?

The MSDS for lead that you have linked says:
"Potential Acute Health Effects: Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of
inhalation."

and:
"Potential Chronic Health Effects:
Slightly hazardous in case of skin contact (permeator). CARCINOGENIC EFFECTS: Classified A3 (Proven for animal.) by
ACGIH, 2B (Possible for human.) by IARC. MUTAGENIC EFFECTS: Not available. TERATOGENIC EFFECTS: Not available.
DEVELOPMENTAL TOXICITY: Not available. The substance may be toxic to blood, kidneys, central nervous system (CNS).
Repeated or prolonged exposure to the substance can produce target organs damage."

So unless you actually get the lead in your body somehow - e.g. by drinking or eating it - you are pretty much safe. Bringing up the Flint case is not really useful when talking about soldering - ingesting heavily contaminated water is not the same as handling a leaded solder wire. Or are you putting solder in your lunch?

Every last substance on this list is EXTREMELY TOXIC, if you don't believe me - go put some cadmium, mercury, or hexavalent chromium in your next glass of water and drink it. Let's see how long it takes for you to change your mind.

Strawman argument. Soldering is not the same as drinking or eating lead particles.

Oh, and a side note - some of those are contact poisons, merely getting them on your skin causes absorption.

Another strawman, because this is not the case for lead - it is marked only as possible irritant and slightly hazardous if you have prolonged exposure. Wash your hands after work and you will be fine.

Leaded solder has been in use for decades and I have never seen a documented case of lead poisoning from soldering. Leaded paint or lead water pipes are another story, though. You have probably had more lead and cadmium exposure from leaded gasoline car exhaust fumes if you are old enough than you could ever get from soldering.

Here is a research study that did actually focus on lead in electronics factory workers in Malaysia - i.e. an environment with significantly higher exposure to both fumes and dust lead than what a normal hobbyist/repairman would ever encounter:
http://www.niosh.org.my/download/jurnal/vol1no2271204.pdf

p. 53 (p 13 in the PDF):

"Although the soldering workers are
exposed to lead during their work, this exposure
does not seem to have any effect on their blood
lead concentrations. Therefore, this suggests that
whatever blood lead concentrations that the
respondents have are not from their workplace
but from the general environment such as
ambient air, food, water, dust from the streets or
paints and perhaps emission from nearby
industries. Since the blood concentrations are
very low, no adverse health effects are seen in
the respondents."

Even the RoHS compliant UK government recognizes lead soldering as not liable to result in a significant exposure:
http://www.hse.gov.uk/pubns/priced/l132.pdf (p. 26) Low temp (<500C) soldering and handling of metallic lead are explicitly mentioned there.

Can we put the scaremongering about leaded solder to rest now? RoHS is about environment protection, so that this crap doesn't accumulate in the environment thanks to our culture disposable electronics and e-waste. It doesn't say that soldering using leaded solder is dangerous as such.

[LordHexahedron]

I think nobody argues that lead is not toxic or that it is not bad for environment, but let's get things in perspective, shall we?

Lead is not bad for the environment.

Except someone did just that

So unless you actually get the lead in your body somehow - e.g. by drinking or eating it - you are pretty much safe. Bringing up the Flint case is not really useful when talking about soldering - ingesting heavily contaminated water is not the same as handling a leaded solder wire. Or are you putting solder in your lunch?

Strawman argument. Soldering is not the same as drinking or eating lead particles.

Oh indeed, but I'm more concerned with when the prototype is eventually disposed of.
how do you think the lead gets in the water in the first place? (usually poor handling of items containing lead), it's not as much a strawman as a slippery slope (Not necessarily the best argumentative form but since people just chuck their items in the bin when they break it can and will eventually end up in the environment, hence why RoHS exists to begin with!)

Another strawman, because this is not the case for lead - it is marked only as possible irritant and slightly hazardous if you have prolonged exposure. Wash your hands after work and you will be fine.

I was referring to some of the items prohibited by RoHS

Oh, and a side note - some of those are contact poisons

Emphasis added for clarity.
Cadmium is worse than lead, but is still not that bad of a contact poison
http://www.sciencelab.com/msds.php?msdsId=9923223
Mercury should be considered a potent contact poison
http://www.sciencelab.com/msds.php?msdsId=9927224

Very hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. Hazardous in case of
skin contact (corrosive, permeator).

There's a very good reason why I phrased it that way in any case, specifically as a general response to this:

ROHS is just another scam to employ people and stimulate the economy. Sorta like global warming. But even less scientific and more knee-jerk, heart-string, and plain dumb.

Leaded solder has been in use for decades and I have never seen a documented case of lead poisoning from soldering. Leaded paint or lead water pipes are another story, though. You have probably had more lead and cadmium exposure from leaded gasoline car exhaust fumes if you are old enough than you could ever get from soldering.

Fair enough - however there's an argument in that you can still get lead in your eyes or ingest it if you forget to wash your hands after touching leaded solder - I personally don't really want to take that risk.
And I'm far more concerned with it getting into the water supply one way or another.

Here is a research study that did actually focus on lead in electronics factory workers in Malaysia - i.e. an environment with significantly higher exposure to both fumes and dust lead than what a normal hobbyist/repairman would ever encounter:
http://www.niosh.org.my/download/jurnal/vol1no2271204.pdf

p. 53 (p 13 in the PDF):

"Although the soldering workers are
exposed to lead during their work, this exposure
does not seem to have any effect on their blood
lead concentrations. Therefore, this suggests that
whatever blood lead concentrations that the
respondents have are not from their workplace
but from the general environment such as
ambient air, food, water, dust from the streets or
paints and perhaps emission from nearby
industries. Since the blood concentrations are
very low, no adverse health effects are seen in
the respondents."

Very interesting, I'll have to read into it a bit later - I only had time to skim it at the time of writing.

Even the RoHS compliant UK government recognizes lead soldering as not liable to result in a significant exposure:
http://www.hse.gov.uk/pubns/priced/l132.pdf (p. 26) Low temp (<500C) soldering and handling of metallic lead are explicitly mentioned there.

Can we put the scaremongering about leaded solder to rest now? RoHS is about environment protection, so that this crap doesn't accumulate in the environment thanks to our culture disposable electronics and e-waste. It doesn't say that soldering using leaded solder is dangerous as such.

Fine by me, I still advocate lead free solder in any case (environmental effects primarily), but yes - I likely overestimate the potential exposure to lead from soldering as I opt for "better safe than sorry", I apologize for any misinformation about potential exposure I may have spread as a cause of this.

[CatalinaWOW]

There must be balance in this as all other things.

I once received a government solicitation that demanded that a piece of equipment containing sensors, computing elements and servomechanisms would contain NO toxic materials and proceeded to list the forbidden materials.  The list started out OK with cadmium and lead, but went on to include most other metals including COPPER.

I have seen people demanding that all heavy metal use be banned, including ALUMINUM and IRON.

The dangers of lead have been used to drive action where the risks are minimal or non-existent.  A shooting range I once frequented was closed, one of the stated reasons being to protect neighbors and employees from lead contamination.  Even though as much lead as practical was periodically collected from the range and recycled.  And though two employees of the range who were directly involved in recycling activities and who spent six days a week at the range for nearly three decades were tested and found to have no detectable levels of lead in their systems.

So lead and other heavy metals (and even metals generally not considered to be particularly toxic) can be accused of far greater danger than really exists.

But lead when used in large quantities, particularly when focused in small areas, can cause very real harm. 

The lead in tetraethyl lead used for decades in gasoline caused a very real and significant increase in lead exposure as measured in the bodies of people near major motorways and also caused measurable symptoms. 

Lead used in shotgun shells, accumulated over decades in marshes and ponds frequented by waterfowl, when combined with the feeding habits of these birds and their unique digestive systems did cause significant health effects in these birds.

The right answer is not panic and total avoidance of these materials, but it is also not total disregard of the dangers and drawbacks.

[Ian.M]

Exactly.  ONE fly-tipped Lead Acid car battery is likely to cause more environmental damage than a lifetime's use of Sn/Pb solder by a hobbyist.  Most hobbyists keep their electronic projects like much loved pets so they wont end up in the eWaste stream for years or even decades + the total volume of lead used is low.   OTOH requiring ROHS for bulk production of throwaway electronics that is likely to end up in landfill is only common sense as the organic acids in the leachate can easily cause a serious heavy metals pollution problem.

The only other factor is personal safety and the many years of experience in the industry tell us that its entirely manageable by good working practices.   Obviously you don't want lead contamination in a household with small children, but there are so many other hazards and hazardous substances associated with electronic construction and repair, that you shouldn't be doing it at all in the same room as children that are too young to understand not to touch stuff or put it in their mouths, and if you keep a clean, safe workshop, the risk of contamination to the rest of the house is negligible.  In fact if you live in a long-established urban area, pre-existing background contamination is a far more serious issue.

[KL27x]

Can we put the scaremongering about leaded solder to rest now? RoHS is about environment protection, so that this crap doesn't accumulate in the environment thanks to our culture disposable electronics and e-waste. It doesn't say that soldering using leaded solder is dangerous as such.

The only problem with this is the environmental concern is also scaremongering bull feces.

And I'm far more concerned with it getting into the water supply one way or another.

W/e lead gets into the water supply? Dealt with the same way any other metallic ions are. Chemical treatment. There's a ton of nasty ions in water that are removed by messing with the pH. The solubility of metal ions in water is extremely low if you increase the pH a couple points.

I can think of a lot worse things in a lot higher quantities that is damaging the environment. Than alloyed/elemental lead. In landfills. Yeah, acidic conditions will make it corrode and dissolve. This why acidic bodies of water are not natural drinking fountains that even animals will drink out of. That water is full of nasties. The dirt under your feet is full of metal oxides of which lead is just one.

In the case of the waterfowls, they are actively EATING the lead shot. This is why it causes any problem. Not only do they eat it, they store in in their gullets, exposing it to air and water, allowing it to oxidize. And then they grind their food with it, breaking off and swallowing lead oxides. And at the low pH (in the birds stomach), lead oxide dissolves, and then passes into the blood stream. Enough to kill the ducks? Maybe, maybe not. But now that it's in the food chain, the predators of these birds can accumulate even higher levels of lead. Well, sure that can eventually be a big problem.

OTOH, if I dump a bunch of lead into a pond in a shape that ducks don't happen to eat, say on pcb's, nothing so big happens from the lead. If I remove all the lead and then lower the pH of the water a couple points to where if would have been able to hold a significant concentration of lead, everything will die from all the other toxic ions leached from the surrounding dirt/rock. Iron oxide is a huge component of dirt. Worrying about lead leaching into water is not as big a concern as a lay person would think. If the water is that acidic, it's poison, anyway.

OTOH, it's very easy for me to convince the average person/government representative that lead is a concern, by laying out a bunch of dots that don't connect. Cause and effect have to be connected before there is any concern.

Did the Roman Empire leave behind a lifeless wasteland? No. Their empire crumbled, but the people and wildlife didn't get sick and die - well, some of their later leaders were apparently wackjobs, but there's no proof it was from lead poisoning vs inbreeding, mental illness, and/or viral/bacterial disease.

In fact, a lot of our metals are mined from places on earth teaming with life. Ironically, the high pH conditions that are amenable to drinkable, life-giving water also means these places are loaded with easily minable mineral oxides that would have dissolved and leached deep into the ground in more lifeless conditions. Brazil is a leading exporter of many of these metals (well, not lead, per se. But a lot of the lighter minerals, though, like tin, for instance), because they are abundant in the RAIN FOREST. The place with the highest diversity and concentration of life on the planet. A place with lots of water and rain. True, if/when acid rain hits the rain forest lots of bad stuff happens. And yeah, it's not good for lead to be leached into our water. But it's not as big a concern as you might think, as long as you don't crap where you eat.

If I water a landfill and it doesn't sprout the garden of eden, elemental lead is not the first concern on my list.

Meh, whadI know. I'm probably not thinking straight from all the lead poisoning.

[stj]

once you have used lead-free solder for as many years as me, you will learn that the chemical formulation of the flux can make more of a difference that the metal blend.
if you get anything "Halide free" for example, good luck soldering onto anything made of brass!

i have tried probably a dozen types of solder and the best i used yet was Stannol solder with Kristall505 flux,
and for faster flow on "special" projects, HS10 flux.

try not to use solder with silver in it.
it may melt at a lower temperature, but it's much harder to re-work later!

finally, 0.7mm is good for general work, 0.5 or 0.3mm for smd work.
1mm is for plumbing

[KL27x]

^ I had a friend in need of solder. Looking at the rolls I had, I decided to give him my 1mm solder, since I hardly use it AND I figured that is what he probably used. In fact, that's the kind he had ordered and was waiting on.*

That left me with a couple rolls of 1.27mm and 1.62mm solder. This is what I use for fine pitch SMD work. Good to know I have the right stuff for plumbing, too. Or is this too big?

*All he had left was the 0.5mm stuff, which his current solder techs can't be bothered with. They're busy doing 0402 rework and even smaller.

I guess my opinion is 0.3mm solder should be the perfect thing for soldering a 100 pin 0.5mm pitch QFP with a needle tip. One pin at a time. I'll be sure to buy some when I want to do that.

[stj]

i would use flow tricks for qfp, or tin the pads and drop the chip with hot air.

0.3mm is good for laying down resistors and transistors though.
and fixing stuff with one or two badly or not soldered legs.

[KMSL]

Hypocrisy, hunters fill nature with tons of lead with millions of buckshots ...  and it's legal !!!

[stj]

Hypocrisy, hunters fill nature with tons of lead with millions of buckshots ...  and it's legal !!!

a lot of ammunition is copper now.

[janoc]

Hi!

I want to know which soldering wire is better (which better looks on end product). Lead-free or leaded.

Considering that you are in Slovenia, EU ROHS directive has answered that for you already - leadfree. Leaded is not legal to put in new products anymore, with some exceptions (aerospace, for ex.).

If you are only planning for hobby use, keep using leaded - much easier to work with.

[janoc]

Can we put the scaremongering about leaded solder to rest now? RoHS is about environment protection, so that this crap doesn't accumulate in the environment thanks to our culture disposable electronics and e-waste. It doesn't say that soldering using leaded solder is dangerous as such.

The only problem with this is the environmental concern is also scaremongering bull feces.

Tell that to the Chinese or African villagers taking apart our "recycled" electronics who are now living in a toxic dump, thanks to lead, cadmium and other nice things that have leached out of it after being dissolved using acids to get gold, copper and other useful metals out.

And the BS about Romans - you have conveniently omitted to say that the average lifespan of an ancient Roman was 35 years. So they likely died before the lead had a chance to accumulate sufficiently in their bodies. Also that were Romans drinking from lead cups and using lead plumbing, not sure how would wildlife get contaminated.

Also the part about rain forest is just nonsense. The forest or animals don't die, because the ores are rarely exposed and birds normally don't eat gold nuggets neither. On the other hand, where there is actual mining going on, the place turns into a toxic wasteland.

However, if you want to see what impact heavy metals in the environment have, just look at the bald eagles. They are an apex predator, so they are accumulating all the metal pollution from their prey. Their heavy decline was pretty much thanks to lead, mercury and cadmium they have picked up from fish or even geese that has been shot with lead shot (http://eaglenature.com/eagle_facts.php )

[Curtis]

There is no doubt, "leaded" solder is the best, not only looking, but the ease in which it flows.
I recently purchased this solder on "ebay" made by "Kester" it is the best I have ever used.

http://www.ebay.com/itm/KESTER-24-6337-0027-WIRE-SOLDER-031-RA-ROSIN-SN63-PB37-66-FLUX-44-CORE-1-lb/182197011876?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D37582%26meid%3Ddc3c5445867c4c4aad1e75754fdfc875%26pid%3D100011%26rk%3D2%26rkt%3D10%26sd%3D182127454776

[LabSpokane]

Lead works better.

Yes it does.

Lead is not bad for the environment.

Yes it is.

Lead is highly insoluble in water. It does not transfer to your skin and into your mouth and poison you. As long as you don't let your solder corrode into lead oxide, it is not dangerous.

Lead oxides form essentially automatically and disperse lead into the environment in contact with water. 

Lead *mining* is the major problem with environmental contamination.  Reduction in lead mining for producing consumer electronics automatically translates into less environmental contamination. 

And for anyone that thinks lead does not affect human health and behavior, you just haven't been paying attention.  It's a problem. 

Lead can be mined responsibly and used responsibly.  And frankly, in many applications for durable goods, lead *should* be used to lengthen the product's lifetime in order to reduce waste, which is the real problem.  RoHS is another overreaching European directive which is self defeating. 

That said, lead is incredibly bad for children, and if I had small children in the home, I would not have leaded solder.  The latest research shows that there is no safe threshold for lead exposure for children. 

[CatalinaWOW]

Lead works better.

Yes it does.

Lead is not bad for the environment.

Yes it is.

Lead is highly insoluble in water. It does not transfer to your skin and into your mouth and poison you. As long as you don't let your solder corrode into lead oxide, it is not dangerous.

Lead oxides form essentially automatically and disperse lead into the environment in contact with water. 

Lead *mining* is the major problem with environmental contamination.  Reduction in lead mining for producing consumer electronics automatically translates into less environmental contamination. 

And for anyone that thinks lead does not affect human health and behavior, you just haven't been paying attention.  It's a problem. 

Lead can be mined responsibly and used responsibly.  And frankly, in many applications for durable goods, lead *should* be used to lengthen the product's lifetime in order to reduce waste, which is the real problem.  RoHS is another overreaching European directive which is self defeating. 

That said, lead is incredibly bad for children, and if I had small children in the home, I would not have leaded solder.  The latest research shows that there is no safe threshold for lead exposure for children.

I understand that you are very concerned about lead.  But if you want to reduce lead mining, you start with the major users of lead.  Electronics is way down on the list.  And as you say, elimination of lead in electronics in durable goods causes problems with waste disposal of all sorts of other materials.  I would only add that all electronics really should be durable goods.  There is no reason to throw a CD player or cell phone or just about any other device away after a couple of years. 

So for me, I think lead solder is a good thing.  It is less likely to get into the environment than most other applications, reduces disposal of other hazardous materials, and is easier to use.

[jitter]

Unfortunately, lots of (smaller) consumer electronics that reach end of life are more often than not stuffed into a bin and ends up on a landfill. I must admit that I did this too and only brought bulky items like CRTs to the recycling depot.
With so many throw away electronics, having lead in them it could easily become a big problem as many small items make up lots of lead too. And BTW, a car battery (that's literally heavily loaded with lead) usually finds it way to the recycling programme because it's so heavy. People just leave it at the garage or dealer that sold them the new one, and they must dispose of them properly (and there's some value in expended batteries, so it does happen).

[CatalinaWOW]

Every country does things differently, so I won't try to generalize, but here in the US it isn't obvious to me why lead in disposed electronics is a big issue.

In this country the vast majority of waste (that isn't recycled) goes into what are called "sanitary land fills".  They are large chunks of land that are usually prepared by putting down a clay or plastic liner to prevent liquids from escaping into the ground.  The waste is then dumped in, and compacted by driving large bulldozers over it.  At the end of each day a layer of dirt is spread over the waste to seal it in.  There is much fault to be found with this practice, but from the standpoint of lead contamination it seems to solve the problem.  There is little new moisture added to the contents due to the grading and sealing of the waste, which tends to cause rainwater to run off of the top, before contact with the waste and which keeps surface water away.  The moisture that does get in and that was originally present usually doesn't get out again.  So the lead will for the most part stay in the landfill.

The contents of these land fills is a nasty mess of rotting food waste, dead animals, broken furniture, discarded plumbing, yard trimmings, stuff picked up off of roadways, plastic bags, punctured inflatable toys and just about anything else you can think of.  Decomposition of the organic material generates methane gas (and some truly amazing foul odors) which is frequently collected and burned, occasionally with the energy being harvested.  No one really understands the long term future of these things.   They will probably remain unhealthy places to dig and forage for centuries, and lead content is likely to be far down on the list of what you should worry about if you do choose to dig into one of these things.

[A.Huggy]

Hypocrisy, hunters fill nature with tons of lead with millions of buckshots ...  and it's legal !!!

a lot of ammunition is copper now.

Maybe it's different there, but here in the US, most projectiles are still lead.  Most rifle and pistol rounds are copper jacketed, but the core of the bullet is lead, and this lead core is exposed at the base of the bullet.  Brass projectiles are starting to gain popularity, but I've never come across a solid copper bullet.

Hunters are one thing, but ranges are worse.  Hunters shoot mainly steel shot these days, and bullets used for hunting probably don't account for much.  A potential problem is the tons of lead shot left behind at clay ranges.  Some ranges try to recover some of the lead from the dirt, but this is not easy.  Most ranges just let it sink into the dirt.  That's thousands of rounds worth of lead shot sinking into the ground every week.

On an unrelated note, in the US it is costly to dispose of lead acid batteries, especially if you have a large volume.  Some places take used batteries from consumers and dispose of them for free, but if you are a business and have a large volume to dispose of, it costs money.  I used to be an IT guy at a small business and we replaced all of the batteries in our UPS's.  I set the old batteries aside in the warehouse for disposal once my boss approved the funds to do so.  There were about 200 pounds of batteries.  When I left the company a couple years later they were still sitting there, but I bet they are in a land fill by now. 

[janoc]

Every country does things differently, so I won't try to generalize, but here in the US it isn't obvious to me why lead in disposed electronics is a big issue.

In this country the vast majority of waste (that isn't recycled) goes into what are called "sanitary land fills".  They are large chunks of land that are usually prepared by putting down a clay or plastic liner to prevent liquids from escaping into the ground.  The waste is then dumped in, and compacted by driving large bulldozers over it.  At the end of each day a layer of dirt is spread over the waste to seal it in.  There is much fault to be found with this practice, but from the standpoint of lead contamination it seems to solve the problem.  There is little new moisture added to the contents due to the grading and sealing of the waste, which tends to cause rainwater to run off of the top, before contact with the waste and which keeps surface water away.  The moisture that does get in and that was originally present usually doesn't get out again.  So the lead will for the most part stay in the landfill.

The contents of these land fills is a nasty mess of rotting food waste, dead animals, broken furniture, discarded plumbing, yard trimmings, stuff picked up off of roadways, plastic bags, punctured inflatable toys and just about anything else you can think of.  Decomposition of the organic material generates methane gas (and some truly amazing foul odors) which is frequently collected and burned, occasionally with the energy being harvested.  No one really understands the long term future of these things.   They will probably remain unhealthy places to dig and forage for centuries, and lead content is likely to be far down on the list of what you should worry about if you do choose to dig into one of these things.

And that makes it somehow OK? Or what did you mean by that?

You have obviously not heard about leaking landfills. Or a landfill exposed by a landslide or flood. Or landfill broken by an earthquake. Or built poorly to begin with to save costs and because nobody will be able to see the defects until many years later. Or many other possible ways the crap could get out and contaminate ground water, for example. The methane, foul smells and rotting organic stuff are perhaps nasty, but least of the problem - given enough time, they will decompose and become harmless humus. The plastics will mostly break up too, only over much longer time spans. On the other hand, heavy metals will sit there pretty much forever, waiting until the barrier layer gets damaged at some point and then leach into water or soil. Building new "superfund" sites, as you call them in the States, doesn't sound as an exactly good waste disposal plan.

Your use of a leaded solder is not an issue (I am using it myself, btw). However, when Apple sells million of iPhones, the majority of those iPhones will wind up in a landfill somewhere in a few years. Even if each phone is using only a few grams of solder - if that solder was leaded (it isn't, fortunately) and if you multiplied it by the number of pieces made and sold, it would make an enormous amount of toxic waste. Let's say an iPhone needs a 1g of solder (probably less, but bear with me), if that was the common 60/40 mix, that makes 1e6 * 1g = 10 tons of solder, out of which 4 tons would be just lead ...  And that is only Apple and iPhones, where are all other smartphone manufacturers, all the TVs we throw away, all those laptops, fitness trackers and whatever other electronic gizmos people cannot live without.

Reducing the amount of toxic stuff that could leach out of the obsolete gear is only a good thing because it is one problem less that we leave to our kids and grandkids to deal with. Doing nothing because "others pollute more anyway" is a really dumb argument in this context.

[Ian.M]

Its time to stop treating eWaste as general waste.  It *should* be treated as valuable ore.   Copper ore deposits have been so heavily mined that typical economic copper concentrations in ore are now well under 1%.  PCBs usually run significantly above that.  Pulverise, pyrolyse in the presence of steam to extract the organics. Acid leach the ash to get a mixed metal concentrate then refine. 

Tax manufacturers and importers punitively on any imbalance between mass of product sold and eWaste recycled. Give credit for mass of product repaired rather than recycled.   

[Sigmoid]

And the BS about Romans - you have conveniently omitted to say that the average lifespan of an ancient Roman was 35 years. So they likely died before the lead had a chance to accumulate sufficiently in their bodies. Also that were Romans drinking from lead cups and using lead plumbing, not sure how would wildlife get contaminated.

Most people are idiots when it comes to averages.

Romans (and pretty much everyone before Pasteur) had incredible levels of child mortality. We're talking about 2 out of 10 children reaching adulthood.

Once you were 18, you were set to live well until 60-70. Even if you were a roman, or a caveman. (Not counting violent death.)

---

Speaking of leaded solder, I'd say use it for prototyping, sell very small batch stuff as kits, and if you sell stuff in larger batches, you'll be getting the stuff reflow soldered anyway (probably outsourced), so let "other people" worry about it.

In the EU, electronics waste has to be collected free of charge by electronics retailers, and there are pretty strict rules on recycling it (so I doubt it ends up in African villages, unless it's smuggled there.) So any lead will be safely handled once your prototypes have outlived their use.

[Ian.M]

There are strict rules in the EU but they don't make it easy for the general public to keep eWaste out of the general waste stream or for small manufacturers or importers to arrange compliant disposal.  eWaste needs to be collected on the same basis as other domestic and light commercial recycling.  The only free market way is to load the environmental costs as a tax on to the initial sale price to provide funds to subsidise the purchase of eWaste so its collection is economic.

[stj]

Maybe it's different there, but here in the US, most projectiles are still lead.  Most rifle and pistol rounds are copper jacketed, but the core of the bullet is lead, and this lead core is exposed at the base of the bullet.  Brass projectiles are starting to gain popularity, but I've never come across a solid copper bullet.

go look at something like Barnes TSX or XPB or TAC-XPD
 

[CatalinaWOW]

And that makes it somehow OK? Or what did you mean by that?

You have obviously not heard about leaking landfills. Or a landfill exposed by a landslide or flood. Or landfill broken by an earthquake. Or built poorly to begin with to save costs and because nobody will be able to see the defects until many years later. Or many other possible ways the crap could get out and contaminate ground water, for example. The methane, foul smells and rotting organic stuff are perhaps nasty, but least of the problem - given enough time, they will decompose and become harmless humus. The plastics will mostly break up too, only over much longer time spans. On the other hand, heavy metals will sit there pretty much forever, waiting until the barrier layer gets damaged at some point and then leach into water or soil. Building new "superfund" sites, as you call them in the States, doesn't sound as an exactly good waste disposal plan.

Your use of a leaded solder is not an issue (I am using it myself, btw). However, when Apple sells million of iPhones, the majority of those iPhones will wind up in a landfill somewhere in a few years. Even if each phone is using only a few grams of solder - if that solder was leaded (it isn't, fortunately) and if you multiplied it by the number of pieces made and sold, it would make an enormous amount of toxic waste. Let's say an iPhone needs a 1g of solder (probably less, but bear with me), if that was the common 60/40 mix, that makes 1e6 * 1g = 10 tons of solder, out of which 4 tons would be just lead ...  And that is only Apple and iPhones, where are all other smartphone manufacturers, all the TVs we throw away, all those laptops, fitness trackers and whatever other electronic gizmos people cannot live without.

Reducing the amount of toxic stuff that could leach out of the obsolete gear is only a good thing because it is one problem less that we leave to our kids and grandkids to deal with. Doing nothing because "others pollute more anyway" is a really dumb argument in this context.

Numbers like 4 tons sound huge, until you think about how it is spread over a large area (most of the developed and semi-developed world since phones are not shipped about before discarding.)

For comparison see the attached graph on worldwide lead production.  Most of that produced in the years from 100 BCE to 500 CE was produced and used in the Roman Empire, and is now soiling the land throughout that region.  I haven't actually summed the numbers, but a very conservative estimate would show 10,000 tons a year over that 600 year period.  A total of 6 million tons.  All leaching into the soil without benefit of modern landfill technology. Apparently the region is now barely inhabitable as a result, with widespread lead poisoning of the population.

 (the graph apparently shows total production over 100 year intervals, but this is dramatically in contrast with other sources that show these numbers as annual production rates.  The annual production assuming it is 100 year totals seems low considering the widespread usage of lead in the empire.  Even if you take the graph at face value you are talking 10s of thousands of tons.)

I agree that others doing worse harm is not an adequate reason for doing harm yourself.  But you are using that argument yourself when you say that you use lead solder for your hobby work. Your 1 pound and my 1 pound and all the other small users in the world do add up to 1000s of pounds.

Landfills do leak and fail.  But expending resources on something that has a tiny, perhaps immeasurable benefit, while having measureable drawbacks is also not an easily defensible position.

[Sigmoid]

There are strict rules in the EU but they don't make it easy for the general public to keep eWaste out of the general waste stream or for small manufacturers or importers to arrange compliant disposal.  eWaste needs to be collected on the same basis as other domestic and light commercial recycling.  The only free market way is to load the environmental costs as a tax on to the initial sale price to provide funds to subsidise the purchase of eWaste so its collection is economic.

They do make it easy. Go to your nearest mall, walk into the Media Markt or whatever consumer electronics retailer, and they will have a bin for e-waste in the customer service section, or you can just hand the customer service clerk your bag of e-waste and they are obliged by law to take it.

Could it be easier? Yes, but open standing e-waste bins sound like a bad idea (corrosion, leakage, stupid people putting regular waste in it, etc.)

[Capa-Alpha]

Every country does things differently, so I won't try to generalize, but here in the US it isn't obvious to me why lead in disposed electronics is a big issue.

In this country the vast majority of waste (that isn't recycled) goes into what are called "sanitary land fills".  They are large chunks of land that are usually prepared by putting down a clay or plastic liner to prevent liquids from escaping into the ground.  The waste is then dumped in, and compacted by driving large bulldozers over it.  At the end of each day a layer of dirt is spread over the waste to seal it in.  There is much fault to be found with this practice, but from the standpoint of lead contamination it seems to solve the problem.  There is little new moisture added to the contents due to the grading and sealing of the waste, which tends to cause rainwater to run off of the top, before contact with the waste and which keeps surface water away.  The moisture that does get in and that was originally present usually doesn't get out again.  So the lead will for the most part stay in the landfill.

The contents of these land fills is a nasty mess of rotting food waste, dead animals, broken furniture, discarded plumbing, yard trimmings, stuff picked up off of roadways, plastic bags, punctured inflatable toys and just about anything else you can think of.  Decomposition of the organic material generates methane gas (and some truly amazing foul odors) which is frequently collected and burned, occasionally with the energy being harvested.  No one really understands the long term future of these things.   They will probably remain unhealthy places to dig and forage for centuries, and lead content is likely to be far down on the list of what you should worry about if you do choose to dig into one of these things.

And that makes it somehow OK? Or what did you mean by that?

You have obviously not heard about leaking landfills. Or a landfill exposed by a landslide or flood. Or landfill broken by an earthquake. Or built poorly to begin with to save costs and because nobody will be able to see the defects until many years later. Or many other possible ways the crap could get out and contaminate ground water, for example. The methane, foul smells and rotting organic stuff are perhaps nasty, but least of the problem - given enough time, they will decompose and become harmless humus. The plastics will mostly break up too, only over much longer time spans. On the other hand, heavy metals will sit there pretty much forever, waiting until the barrier layer gets damaged at some point and then leach into water or soil. Building new "superfund" sites, as you call them in the States, doesn't sound as an exactly good waste disposal plan.

Your use of a leaded solder is not an issue (I am using it myself, btw). However, when Apple sells million of iPhones, the majority of those iPhones will wind up in a landfill somewhere in a few years. Even if each phone is using only a few grams of solder - if that solder was leaded (it isn't, fortunately) and if you multiplied it by the number of pieces made and sold, it would make an enormous amount of toxic waste. Let's say an iPhone needs a 1g of solder (probably less, but bear with me), if that was the common 60/40 mix, that makes 1e6 * 1g = 10 tons of solder, out of which 4 tons would be just lead ...  And that is only Apple and iPhones, where are all other smartphone manufacturers, all the TVs we throw away, all those laptops, fitness trackers and whatever other electronic gizmos people cannot live without.

Reducing the amount of toxic stuff that could leach out of the obsolete gear is only a good thing because it is one problem less that we leave to our kids and grandkids to deal with. Doing nothing because "others pollute more anyway" is a really dumb argument in this context.

Electronics in landfills have never been the problem! Here's the breakdown of Lead (pb) composition in landfills per a 2006 study:

• Electronic Solder: 0.49%
• Non-electronic solder: 0.70%
• Pipes, Trap, Extrusions: 0
• Brass/Bronze Ingots: 0.72%
• Casting Metals: 1.13%
• Cable Covering: 1.40%
• Sheet Lead: 1.79%
• Ammunition: 4.09%
• Paints, Pigments: 4.78%
• BATTERIES: 80.81%

So I think you can safely conclude that the culprit in most "leaking landfill" cases will be lead-acid car batteries, which will continue to be the source of lead contamination for years to come. Comparing leaded solder and batteries in landfills is like comparing someone with a zit on his back to someone with melanoma! It does not contribute to the lead contamination issue in any meaningful way.

I have some pretty strong feelings on lead-free solder. I think the RoHS regulations are based on bullcrap as opposed to science. Here are a couple of factoids you should know about leaded vs lead-free solder.

1. Leaded solder fume is NOT composed of lead fume. Your iron would have to reach temperatures well above 1100°F (593°C) to vaporize, temperatures which the vast majority of soldering irons do not even have the capability to produce. You get lead poisoning via ingestion, that is eating with dirty hands or smoking a cigarette after handling the solder roll. The fumes you see are flux fumes (which are noxious yes, but lead-free). And you still should extract the flux fumes with lead-free because the new fluxes are more concentrated, noxious, odorous and trigger a host of allergic reactions (asthma & skin rashes in particular).
2. Lead-Free solder has a significantly higher melting point (from 217-222°C) than leaded solder (183°C when using eutectic 63/37). The higher melting point is exponentially more corrosive to the life of your soldering iron tips. The higher the tin content of lead-free, the more destructive and corrosive to iron plated soldering iron tips. Plus the higher the tip temperature, the higher the oxidation (corrosion) of the tip. When using similar temperatures, Your tips will last up to 4 times longer using leaded solder!
3. The higher melting point of lead-free solder is also significant because now all lead-free consumer electronics boards are are melted at much higher temperatures, causing higher worldwide BTU/electrical use in manufacturing, resulting in more coal use to generate the electricity, and more carbon pollution! We are poisoning the atmosphere (this comes from a 2005 US EPA report)!
4. Lead-free solder does not wet as well, has a much grainier/dull appearance and is much harder to hand solder with. 
5. Although Lead-free solder reliability has gotten better in the past 10 years, it is nowhere near the reliability of leaded solder. You can expect poor wetting, joint lifting/cracking, and general solder joint failure in a much more rapid period of time. There is a reason most lead-free products don't last longer than 3-5 years these days!
6. Finally, lead-free solder has an insidious issue called "tin whiskers" which affect long-term reliability. It's been a known problem for ages (first reported in 1946!!!) and can affect any lead-free joint. They still don't know exactly why or how it happens. Tin Whiskers are spontaneous filaments of crystalline tin that grow 1-2mm (from 1 month to-20 years) that have caused documented failures to aircraft relays, heart pacemakers, 5 Navy missiles, 6 satellites, Patriot, F-15 radar, nuclear reactor and much more. Swatch switched back to lead-free solder in the  mid-2000's after all their watches started shorting out after a year! Guess what resolves the tin-whiskering problem?: the addition of 3% lead, something that was discovered in 1950 when a slew of tin-whiskering issues occured using pure tin solder. But 3% lead is not allowed under RoHS regulations. Tin-whiskering is the primary reason that lead-free solder is not allowed in any NASA pcb nor used for medical, military, avionics,  or any other electronics that requires long-term reliability! Google "NASA tin-whiskers" and prepare to be blown-away!

So wash your hands frequently after use and keep your leaded solder away from the kiddies and all will be better!

I'll come off my high-horse now ... ;-)

[janoc]

Jeeze ... Waaay to miss the point completely, man.

I have never spoken about solder fumes or tin whiskers - sure enough, fumes are not and whiskers are a problem. But that's not the point here.

The point of ROHS is trying to keep as much mass produced  "throw away" lead (i.e. not avionics, not your hand-made solder joints, not your car electronics ...)  out of the environment as possible, because that shit accumulates in living beings (such as the things we eat afterwards) and is nigh impossible to clean up once it gets there. Leaded gasoline also worked better for the engines but we are using unleaded and catalytic converters today.

I don't know where did you get your statistics saying that 80% of lead in landfills is from batteries from. Is it legal to dump car batteries (or even batteries in general) in landfills in the US? I somehow doubt it, but I am not living there. It certainly isn't here. It would be also economically stupid thing to do, because unlike lead from solder, lead from batteries is perfectly recyclable and cheaper than buying new metal - the battery companies are buying used batteries up for exactly that reason.

But no matter what, you are still pushing the argument that because other things pollute more, we don't need/shouldn't do anything about the stuff that pollutes less. 

[SeanB]

Mining lead from a shooting range.....



An afternoon of work with a pan, and the result is a few lead ingots with only some simple work. More lead in the soil there as bullets than in a lot of ores In a century people will be mining dumpsites as a valuable resource, as opposed to an eyesore. It is economical to refine sewage sludge from a proper sewage works ( the final product that is not digested and which is not water) into the component precious metals, copper and iron that was dissolved in the sewage water.

[jitter]

But no matter what, you are still pushing the argument that because other things pollute more, we don't need/shouldn't do anything about the stuff that pollutes less. 

And that's the whole point of RoHS.
And the (back then possibly foreseen) result has been that manufacturers outside the EU were going to keep it simple and switched to leadfree for all production, not just for the part going to the EU, resulting in a global improvement.

RoHS is more than just about lead, 9 other highly toxic substances are under that directive (quotes below from this article).
Perhaps some find RoHS questionable because it is much more concerned with the much less directly visible long term effects of small concentrations on the health of people than with the short term effects of high concentrations on individuals:

RoHS and other environmental laws are in contrast to historical and contemporary law that seek to address only acute toxicology, that is direct exposure to large amounts of toxic substances causing severe injury or death.[14]

Our parent's days to party on and let the next generations clean up the mess are over because we ARE that next generation! It's only logical that things like RoHS are put into existence.

And to those opposed to RoHS, please read this bit and draw your conclusions:

American electronics sent offshore to countries like Ghana in West Africa under the guise of recycling may be doing more harm than good. Not only are adult and child workers in these jobs being poisoned by heavy metals, but these metals are returning to the U.S. "The U.S. right now is shipping large quantities of leaded materials to China, and China is the world's major manufacturing center," Dr. Jeffrey Weidenhamer says, a chemistry professor at Ashland University in Ohio. "It's not all that surprising things are coming full circle and now we're getting contaminated products back."[12]

My conclusion: as long as "recylcing" is going to shift and not solve the problem, then perhaps we shouldn't use those heavily toxic substances in the first place and things like RoHS are a GOOD thing, not a nuiscance.

[CatalinaWOW]

Your use of a leaded solder is not an issue (I am using it myself, btw).

But no matter what, you are still pushing the argument that because other things pollute more, we don't need/shouldn't do anything about the stuff that pollutes less. 

I am still trying to understand the logic that reconciles these two statements.  Apparently there is some threshold in your mind that authorizes the use of dangerous substances, and in your humble judgement your usage is below this threshold.  But in your humble judgement other very minor uses of lead are above that threshold.

So the question is:  What is that threshold and how is it established?  Numerical data presented by several of us here is apparently not pertinent to the issue.

[Sigmoid]

I think it's short-sighted to say that ROHS is pointless. It definitely is a force for good. Lead-free solder is NOT a problem in reflow soldering, and that's how pretty much all non-prototype electronics is made today.

The question was which solder is better for hand soldering, and I think it's clear that leaded is superior, without posing any health hazard to the user, unless they are a complete muppet. (Flux fumes are kinda bad, but I don't smoke or drink to compensate, lol.)

Anyway, I remember hearing about eutectic lead-free at the NYC Resistor hackerspace, but I couldn't really dig up any definitive result on the topic since. Anyone know of a eutectic lead-free formulation that's actually available. My biggest gripe with these "mostly tin" lead-frees is how long they take to set, and how they crystallize...

[janoc]

I am still trying to understand the logic that reconciles these two statements.  Apparently there is some threshold in your mind that authorizes the use of dangerous substances, and in your humble judgement your usage is below this threshold.  But in your humble judgement other very minor uses of lead are above that threshold.

So the question is:  What is that threshold and how is it established?  Numerical data presented by several of us here is apparently not pertinent to the issue.

You are trying to find/fabricate a controversy where none exists. The OP was asking about solder for hand soldering, objectively leaded is better for that, that's also why I am using it. I am also producing so little leaded waste on my bench (and dispose of it properly) that it is not a concern.

The second argument was about putting mass produced quantities of stuff into landfills all over the world. I hope you see a difference there. Moreover, landfills are not a proper method of disposing of electronics by definition, even though it is (sadly) the most common. If everybody was recycling their phone and TV and what not properly, there wouldn't be the need for lead free solder nor directives like RoHS to begin with. Sadly, humans are rarely so enlightened so they need to be "motivated" by the regulation for the common good.

[tautech]

Maybe it's different there, but here in the US, most projectiles are still lead.  Most rifle and pistol rounds are copper jacketed, but the core of the bullet is lead, and this lead core is exposed at the base of the bullet.  Brass projectiles are starting to gain popularity, but I've never come across a solid copper bullet.

go look at something like Barnes TSX or XPB or TAC-XPD
 

Exactly.
There are some areas where you can only use non lead hunting projectiles now but more widespread is the banning of lead shot in shotgun shells when used near waterways. Not so much for the risk of water pollution but to eliminate lead shot from the food chain especially in shallow waterways where it gets consumed by waterfowl and then is directly toxic to them and has a direct impact on populations and then ultimately the sport.

[CatalinaWOW]

I am still trying to understand the logic that reconciles these two statements.  Apparently there is some threshold in your mind that authorizes the use of dangerous substances, and in your humble judgement your usage is below this threshold.  But in your humble judgement other very minor uses of lead are above that threshold.

So the question is:  What is that threshold and how is it established?  Numerical data presented by several of us here is apparently not pertinent to the issue.

You are trying to find/fabricate a controversy where none exists. The OP was asking about solder for hand soldering, objectively leaded is better for that, that's also why I am using it. I am also producing so little leaded waste on my bench (and dispose of it properly) that it is not a concern.

The second argument was about putting mass produced quantities of stuff into landfills all over the world. I hope you see a difference there. Moreover, landfills are not a proper method of disposing of electronics by definition, even though it is (sadly) the most common. If everybody was recycling their phone and TV and what not properly, there wouldn't be the need for lead free solder nor directives like RoHS to begin with. Sadly, humans are rarely so enlightened so they need to be "motivated" by the regulation for the common good.

I am not trying to create controversy.  I am trying to understand.  We all agree that leaded solder is better for hand soldering in terms of joint quality, ease of use etc.  It has been asserted by some on this thread that the toxic qualities of leaded solder overbalance the benefits.  That it is not appropriate for hand soldering.

One explanation of your position could be in your statement that you properly dispose of the lead you use when soldering.  I know that this is somewhat possible in your country in the sense that there are recycling points for electronics.  In this case there is no inconsistency in the argument that no amount of lead is too small to avoid.  I don't know if those collection points also collect tip wipe pads, loose solder flakes, lead dust and the like.  I have no idea what the recycling process is in your country.  It is widely true in the US that this recycling occurs in the US through transfer to third world countries for disassembly/re-use, so sending to a recycling center is only part of the process of keeping lead out of the environment here.

I do know that I am well into my third pound of solder, and I am far from the most prolific hobby builder in the world or even in this forum.  From this it would be easy to estimate that tens of thousands of pounds of solder are used by hobbyists.  This may well be no concern.   I personally believe it to be, even without special recovery and recycling efforts.  Several on this thread show great concern about lead contamination of the environment.  I would like to understand the thresholds which are appropriate, both to guide my own practices, and to inform others who are curious.  My lack of concern my be totally incorrect. 

Because I am an engineer, I like to see numbers and measurements around those thresholds, and appropriate algorithms to relate those numbers to the factors being controlled.  Blood levels of lead that are dangerous are relatively well known, barring any controversy about sub-clinical affects.  (The assertion that even though we cannot measure any health impact, there must be some negative effect since higher dose rates cause problems.  This path would say that no amount of lead use is acceptable.)  The path from lead in most applications to a blood level is very touchy feely.  Unsatisfying.   I am only aware of six areas where there is any real science on the connection between lead usage and toxicology.  Leaded gasoline, leaded paint, lead plumbing, lead glazes on ceramics, workers in lead smelters/foundries and the like, and use in ammunition.  All of those involve either lead quantities orders of magnitude larger than in the electronics industry or unique chemistry which doesn't apply in general.

[tautech]

We need all be concerned about environmental lead in the "big" picture and this is exactly why manufacturers have embraced ROHS. Lead problems are well known and becoming more manageable especially with lead slowly being removed from fuels where AFAIK it was the biggest vector for lead to be introduced into the environment.

When we look at the poll reference we see an overwhelming preference for lead based solder that might indicate hobbyists and the like consider the quantities used are so small as to have little impact.

BTW CatalinaWOW the timber treatment industry where CCA ( Copper Chromium Arsenic (Lead)) is used has lead pollution problems and staff involved in this industry in NZ undergo lead blood level checks.

[IanB]

Several on this thread show great concern about lead contamination of the environment.

But even this needs qualification. All the lead that has ever been mined was in "the environment" to start with. More specifically, we took it out of the natural environment by mining it and introduced it into the man-made environment. Upon disposal it gets put into some other environment.

So to define the potential harm, we have to define which environment we are talking about. It's complicated.

[stj]

We all agree that leaded solder is better for hand soldering in terms of joint quality, ease of use etc.

no we dont.
i dont - i say that the right lead-free solder performs just as good as leaded when soldering and the joints are stronger afterwards.
that's a scientific fact btw.

[CatalinaWOW]

We all agree that leaded solder is better for hand soldering in terms of joint quality, ease of use etc.

no we dont.
i dont - i say that the right lead-free solder performs just as good as leaded when soldering and the joints are stronger afterwards.
that's a scientific fact btw.

I won't argue with that.  This depends a lot on your definition of performance. 

AFAIK all the lead free formulations require tighter process controls, but do achieve good results with those controls.  (Translates into more care or more skill and a higher quality iron.) 

A stronger joint is not always desireable, but may be.  Depends on your boards, the thermal and mechanical stresses they see and the components you are using.  In many cases a leaded solder joint releaves stress that would otherwise exceed the capability of the board or an attached component.  I have not yet encountered a situation where the stronger joint cannot be designed around, but have run into many situations where designs had to be changed to accommodate these issues.  Maybe it is due to the old-fashioned design practices in the places I have been, but I have not yet encountered a situation where the higher strength of the lead free joints was utilized in a positive fashion, either to reduce area of a pad used for mechanical attachment or to allow components to survive higher vibration loads.

Tin whiskers are still an unknown.  There are lead free formulations that don't seem to have a problem, but there is not enough time under the belt to be sure of this.  In many cases this won't matter.  It is hard to imagine hobby applications where it really matters.  My thinking is heavily contaminated by my working career, where reliability failures could easily result in someones death, or waste of truly stunning amounts of money.

As with all engineering problems, the real issue is defining the question.  What is important to you or your application.  Since those answers vary, the optimum solutions vary.  I don't disagree with different solutions, but I would like to understand the underlying reasons and understand if they are rational given the problem statement.

[madires]

The strength of solder joints reminds me of something I've heard about SnPbAg solder and mechanical stress. Are SnPbAg solder joints more resistent against mechanical stress, like vibration, than classic SnPb joints? Any idea about the factor? How does it compare to lead-free (SnCu and SnCuAg)?

[CatalinaWOW]

The strength of solder joints reminds me of something I've heard about SnPbAg solder and mechanical stress. Are SnPbAg solder joints more resistent against mechanical stress, like vibration, than classic SnPb joints? Any idea about the factor? How does it compare to lead-free (SnCu and SnCuAg)?

I'm a EE, not a mechanical engineer, so I can't really answer your question.  But I've watched mechanical engineers work on these problems and there is no simple answer.  Parts, boards and mountings all become parts of a multi-resonant system.  Different solder formulations will change resonant frequencies and Qs.  Whether that is better or worse depends on the vibration driving the system.

It is kind of like asking whether bigger resistors are better than small ones for amplifier design.  The answer is that it depends.  If you really need to know the answer you need to do the tedious and complex work to find out for your problem.  In most cases it isn't that important and won't be a design driver.

[stj]

this may help - that's what datasheets are for. 

[jitter]

Thanks for the link to this datasheet.

The mechanical strength figures are all better than that of Pb-containing solder. It confirms what I was told some years ago by a training company that was giving us solder courses (ISO requirement). Back then they said that empirical data was showing that even though Pb-free solder joints may not look very nice, they are actually stronger than Pb-containing solder joints. One can't judge a book by its cover...

[madires]

More to read:
- Reliability of Joints Formed with Mixed Alloy Solders
  http://publications.npl.co.uk/npl_web/pdf/matc85.pdf
- Board level reliability
  http://www.infineon.com/dgdl/board_level_reliability_tin_plated_components_v1_1.pdf?fileId=db3a3043132679fb01132f4a7131049c
- Database for Solder Properties with Emphasis on New Lead-free Solders
  http://www.msed.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf

[Sigmoid]

no we dont.
i dont - i say that the right lead-free solder performs just as good as leaded when soldering and the joints are stronger afterwards.
that's a scientific fact btw.

Nope. A scientific fact is, for example, the resilience of solder joints after a standardized, controlled application.

Which solder is "better" is an engineering decision. Sometimes lead free can be better, for example in reflow process. (I'm not saying it IS though, hardness is one thing, flexibility is another - something can be more rigid and less resilient, like a bamboo and an oak tree compared...)

However, "better" is not synonymous with "gives the best results under ideal circumstances". In that spirit, asm IS the "best" programming language ever. In reality it's only feasible for a minute subset, like .01% of all software development problems.

Leaded solder is more likely to provide consistently good results under a wide range of circumstances. Lead free provides inferior results under a significant part of that range (eg. less that skilled workforce hand soldering).

Engineering means taking the scientific facts, and making the right compromises. Without environmental concerns, as an engineer, I say leaded is far superior in hand soldering, because assuming an average factory with average workers, it's less likely to result in defects. As for prototyping, it's less likely to result in lost time, ruined parts and a very pissed-off engineer.

[stj]

Leaded solder is more likely to provide consistently good results under a wide range of circumstances. Lead free provides inferior results under a significant part of that range (eg. less that skilled workforce hand soldering).

"chicken shed manufacturing" as we used to call it, is not my concern - it shouldnt exist.

[CatalinaWOW]

More to read:
- Reliability of Joints Formed with Mixed Alloy Solders
  http://publications.npl.co.uk/npl_web/pdf/matc85.pdf
- Board level reliability
  http://www.infineon.com/dgdl/board_level_reliability_tin_plated_components_v1_1.pdf?fileId=db3a3043132679fb01132f4a7131049c
- Database for Solder Properties with Emphasis on New Lead-free Solders
  http://www.msed.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf

Good stuff.  Some interesting points from the linked material

In the first paper-

"Joints with lower ultimate shear strength generally give the better first failure performance."

"Mixed alloy joints in this study generally gave better or equal first failure performance to the original alloys."  Implies that at least from a reliability standpoint there is still work to be done on finding the "best" lead free solder.  Apparently the ad-hoc alloys created during these rework operations are pretty good.

The third paper is an excellent survey showing the various properties that must be considered in selecting the "best" solder for an application.

[jitter]

Look at this paper's conclusion on different solder alloys and thermal cycling. It contradicts the commonly held belief that lead containing solder gives the better joint.

Conclusions
The data generated from TG1 and TG2 suggests that all three lead-free alloys have a greater characteristic lifetime compared to eutectic Sn/Pb in 0/100 °C temperature cycling. The Sn/Ag alloy showed the highest Eta, which was twice as great as that of Sn/Pb

Leadfree solder may have some different issues than lead containing solder, but when the leadfree soldering process is done right, it gives longer lasting results.

[tooki]

Lead is not bad for the environment.

Lead does not significantly vaporize at soldering temps. When you get lead closer to its BOILING point than its melting point, then you can start worrying about lead poisoning from lead vapor.

Lead is highly insoluble in water. It does not transfer to your skin and into your mouth and poison you. As long as you don't let your solder corrode into lead oxide, it is not dangerous.

the MSDS for lead disagrees.
http://www.sciencelab.com/msds.php?msdsId=9927204

Lead is extremely bad for the environment if a large amount gets into the water supply, hence why it's labeled as an environmental hazard, the flint crisis is a good recent example of this.
http://www.cnn.com/2016/01/11/health/toxic-tap-water-flint-michigan/

Lead is VERY TOXIC and should be handled with extreme care.

You do realize that MSDSs are the Chicken Littles of occupational safety? The MSDSs for common household chemicals are terrifying.

And you realize that even the Flint incident is far more complex than "Lead's baaad, mmmkay"? Lead pipes tend to be quickly passivated thanks to the layer of limescale that builds up almost instantly. Flint's mistake was to allow the water to become very acidic, which dissolved the limescale layer, exposing the lead itself. Lead water pipes are common worldwide, because it normally causes no problems, so you just swap it when the pipe fails.

Environmental lead isn't from electronics, it's from tetraethyllead, lead paint, and car batteries. (And in mining dross.) And remember also that in e-waste disposal, the vast majority of the lead we're dealing with isn't in solder, it's in the heavy lead glass of CRTs. One CRT contains far more lead than all the solder in all the (contemporary lead-bearing) electronics you owned at the time.

It's years after RoHS and we've basically only now figured out how to make it perform as well as leaded solder. Most likely, lead-free solder was a complete waste of time and net loss for the environment.