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

[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.