Lead-free Facts and Myths?

[phoenix1234]

Hello guys,

Approximately 8 months ago, when I changed the springs of my Filco Majestouch 1 to 67g, I used lead-free solder to mod it. Today, I want to change the type of lube and the springs so I need to desolder it.

Therefore, I have an opportunity to make a small review to compare between lead-free solder and lead solder on modding mechanical keyboard.

The 3 solder candidates are
+ Sparkle Esc Lead-free solder M705 Sn/Ag3.0/Cu0.5

Specifications
http://www.senju.com/images/pdf/Sparkle%20ESC%20F3%20M705.pdf
+ Kester 63/37 core 245, no-clean
+ Kester 63/37 rosin core 44

After a test, here are what my opinions

Usability
- Lead-free solder requires more efforts to solder and desolder. It requires more temperature to melt but it flows slower. So it is harder to solder with normal soldering irons. Plus, it is easy to get the pcb burnt when desoldering because of high temperature required and slower speed of flowing. In this test, I need to set the temperature to 375oC.
- Here is what I have after desoldering (lead-free solder)

- 63/37 Lead solder has low and fixed melting temperature. Therefore, it is easier to use and lower chance to get the pcb burnt.

Reliability
- Long story short, even I did not see any issue with lead-free solder but according to this  article from NASA, the reliability of lead-free solder is low (page 73 to 75) http://nepp.nasa.gov/whisker/reference/tech_papers/2011-kostic-Pb-free.pdf

Beauty
- Obviously, lead solder is shinier, I believe all of us are surprise by the shinny of G80 PCB when we open it. From left to right :
1) Lead-free 2) Kester 44 3) Lead-free 4) Kester 245

*In the picture, as you can see, there is a blur layer on lead-free joins.

Safe
- According the environmentalists, lead-free solder is better for the environment but I'm not 100% sure about that.


In conclusion
If you are looking for a good, easy to use and shinny solder for your keyboard projects, you can go for the Kester 44, I believe you will never turn back (e.g. this GB http://geekhack.org/index.php?topic=54316.0)

However, if you already have the lead-free solder or you want something environment friendly, go for the lead-free solder.

Update 11/05/2014:
After I received the G80-8100 (M- Manufactured in 2000) from this great finds
http://geekhack.org/index.php?topic=57152.0

I tried to do the comparison between type of solder. Plus I also tried to see how many times soldering/desoldering the G80-8100 PCB eyelets can bear before it broken


1 and 2: Default Cherry
3: Kester 63/37
4: Multicore 63 37
5: Asahi 63 37
6: Asahi 60 40
7: Asahi Sn 99.3% Cu 0.7% (+ extra flux)
8: Default Cherry
9 and 10: Cherry PCB eyelets after 7 times of soldering/desoldering
11: Asahi Sn 96.5% Ag 3.5%
12: Asahi Sn 99.3% Cu 0.7% (no flux)
13: Spackle M705 Sn/Ag3.0/Cu0.5 (+ extra flux)
14: Default Cherry

Some highlighted points:

Kester/Multicore/Asahi 63/37 have identical appearance.
Asahi 60/40 is a bit darker but it is hard to be noticed.
Asahi Sn 99.3% Cu 0.7% with flux is shinier than Asahi Sn 99.3% Cu 0.7% with no flux.
Spackle M705 Sn/Ag3.0/Cu0.5 is the slowest speed of wetting. It flows very flow comparing to the rest.
All lead-free solders is less shiny than the lead solder. It has white colour closer to tin material.

[davkol]

- According the environmentalists, lead-free solder is better for the environment but I'm not 100% sure about that.

If reliability is worse in actuality, it's almost definitely worse in the long term. More waste, obviously. Moreover, higher temperature implies more energy consumption. It's the same kind of BS as "let's save the environment! (and move production facilities to 3rd world countries...)"

[Grendel]

I use no-clean Sn62/Pb36/Ag2 for all my soldering needs and will continue to do so as long as I can get that stuff. The whole RoHS thing is one of the most costly follies politicians have come up w/. Here's a good read about lead-free solder problems.

[user 18]

I just remember not to lick my board or inhale solder fumes.

I use 60Sn/40Pb .032" with rosin core for larger joins (such as switches) and 63/37 .025" for smaller stuff (such as repairing wires chewed by my cat and other finicky projects).

Everything works great, never had any problems with anything that wasn't my own fault. Never used lead-free based on advice from my dad, a retired engineer.

[eth0s]

Well, I just have a couple comments:

1.  I don't think you need to desolder the switches to change the springs and lube.  You can pop them open, while they are still mounted to the PCB.

2.  Lead poisoning from solder fumes is not an environmental issue, it's a health issue, as in your health, not the health of the planet.  Lead, or any heavy metal for that matter, will cause brain damage if you ingest it.  Inhaling vaporized heavy metal is the most dangerous form of heavy metal poisoning, because it goes from the lungs directly to the brain, via the bloodstream.  The Bad News:  You will inhale vaporized lead fumes, if you solder with lead based solder.  That is a fact.  You can mitigate the risk to your health if you can wear a mask, and the better your mask, the less lead you will inhale.  The "Good" News:  As an adult, the amount of lead fumes that you have to inhale is very large before you will notice any brain-damaging effects that will lower your intelligence.  If you soldered every day for a year with lead based solder, you would probably start to notice some diminished mental capacity.  However, a few hours spent soldering on a Saturday, will put a tiny amount of lead into your brain, but it will not cause noticeable damage.  Although the effect is cumulative.  Every time you ingest lead, it adds to the last time you ingested lead.  Your body stores the lead in your bones, teeth and fat.  If you have lead stored in your body, a tiny amount will get excreted through urine every day, but it is incredibly slow process.

[user 18]

Well, I just have a couple comments:

1.  I don't think you need to desolder the switches to change the springs and lube.  You can pop them open, while they are still mounted to the PCB.

PCB mount, yes. Plate mount, no.


You don't need to tell me about health effects, I'm in premed, I've worked in health for years, and know more in that regard than most people would ever want to. That said, I was probably less specific than I could have been. When soldering for an extended period of time, I do wear a mask, for quick jobs I don't bother. During the soldering process, when the maximum amount of lead fumes would be in the air, I am actively holding my breath or exhaling, regardless of the mask or not. Not a perfect solution by any means, but better than snorting solder fumes like some drug

As hobbyists, if we take proper precautions, we should be fine, for the most part. If you're doing a lot of soldering, you may want to look into  a vacuum station or something that sucks up the released vapours and filters them, similar to how spraypaint booths work. Not sure how expensive those are in practice, but the idea seems solid.

[mkawa]

i've written quite a bit about when and how leaded solder is dangerous.

http://geekhack.org/index.php?topic=40060.msg1315060#msg1315060

the short answer is that you have to either have very fine solid particles sitting around that can aerosolize, or you have to turn the material into a gas. lead doesn't turn into a gas until you hit > 1000C, and that's _low_ for a metal. so in short, the lead in solder doesn't vaporize. you're only worried about flux fumes.

the switch to no clean, synthetic flux formulations and leaded solder was driven by two things:

first, EU directive RoHS requires reduction in lead content to near zero for devices sold into europe, and additionally stages in requirements for 10 and 15 year recycling plans for all electronics. the impetus here isn't standard metals used in electronics devices (because you can always say, "oh, go ahead thresh it up and then toss it in a centrifugal crucible!") but the plastics. many plastics have no reconstitution options. ptfe and acetal both release a ton of formaldehyde when melted down, other stable plastics will degrade and then become impossible to polymerize again. shape and thickness of parts is also an issue. blow-molded PET is easy to recycle, but a huge block of PET is a lot harder to, because it takes a crapload more energy to melt it. the other problem is large quantities of heavy metal with low phase change transition points. hence the issue with lead. when you toss lead into a centrifugal crucible, it is highly likely to vaporize. when you bury it without melting it, it's highly likely to migrate into eg groundwater. toss it underwater and you're now slowly poisoning huge amounts of sea creatures which will pass on their lead poisoning to anything that eats them. since lead is used in solder, which is the most prevalent metal alloy in most electronics, mass production of electronics with leaded solder produces a crapton of difficult-to-recycle-and-dangerous-to-not-recycle lead.

second, no clean flux. this was very much driven by the industry's desire to save money by not having to clean every board coming out of the wave soldering machines. once the factories discovered that people were making them clean up their solvent waste instead of just dumping it into a nearby body of water, the flux residue cleaning step became significantly more expensive. a flux is considered "no clean" if its residue can be left on a circuit board without damaging anything for the MTBF of the board. Kester RA is considered no-clean, however i make a point of instructing people to clean it off because a) it's nasty, b) it's nasty and c) it's still mildly corrosive and can cause boards to need rework earlier than otherwise.

so, to be clear, the engineering tradeoff in designing a flux is to compose a chemical which is corrosive enough to eliminate oxide layers so that the solder wets onto the metal joints, but not so corrosive that it damages electronic components. BUT WAIT! if it's corrosive, it's not no-clean, right? and if it's not corrosive, it's a crappy flux, right? YEP!

NEXT POST! why the combination of these two industrial migrations makes for unreliable junky electronics.

[Grendel]

lead doesn't turn into a gas until you hit > 1000C, and that's _low_ for a metal. so in short, the lead in solder doesn't vaporize.

Yea, lead's boiling point is 1749°C/3180°F. There is no lead vapor when soldering. Would I breathe soldering fumes ? No, regardless of what metals are used. Fans are your friends

[user 18]

Trawling through several medical and industrial databases I have access to through school. Can't find any information about lead fumes from solder, but there's tons of data out there on the toxicity of the flux in the solder fumes. This leads me to believe that there is no correlation between the use of lead-containing solder and increased lead content in the body. However, as Mkawa and Grendel say, that still doesn't make the fumes any safer.

What seems to be a good summary of this conversation: Soldering with, for example, 60/40 solder won't cause plumbism (lead poisoning), but the fumes still aren't safe. For long periods of solder work, wear a mask and work in a well-ventilated area.

Additional point of interest to eth0s: plumbism doesn't necessarily manifest as neurological problems. It can also affect blood pressure, among other things. It does tend to manifest primarily as mental impairment in developing children. Not sure about the precise age range defined as "developing children" in the article I read though -- some sources would keep that label until brain development is complete, which isn't until the 20s at the earliest.

[Melvang]

I would also like to point out that "dust masks" sold at big box home improvement stores do absolutely nothing for fumes and gasses.  They are meant for nusence dusts only (grain dust, saw dust, general dirt).  They are not meant nor will protect you from any gasses or fumes in any way, shape, or form.  For this you need a respirator.  In my construction trade in order for a contractor to have us do anything with one we have to be fit tested by an authorized doctor and have a physical done (mostly for lung function) before we could even put one on.

After you go through all this you still need to get filter cartridges.  Ones for particulates (dust and dirt) are good until you can't breath through them.  In fact the dirtier they get the better they filter out the crap in the air.  Now for gasses and fumes you have to get certain cartridges for certain gasses.  And these were only good for 3 days after the sealed bag that contained them were opened.

[user 18]

I would also like to point out that "dust masks" sold at big box home improvement stores do absolutely nothing for fumes and gasses.  They are meant for nusence dusts only (grain dust, saw dust, general dirt).  They are not meant nor will protect you from any gasses or fumes in any way, shape, or form.  For this you need a respirator.  In my construction trade in order for a contractor to have us do anything with one we have to be fit tested by an authorized doctor and have a physical done (mostly for lung function) before we could even put one on.

After you go through all this you still need to get filter cartridges.  Ones for particulates (dust and dirt) are good until you can't breath through them.  In fact the dirtier they get the better they filter out the crap in the air.  Now for gasses and fumes you have to get certain cartridges for certain gasses.  And these were only good for 3 days after the sealed bag that contained them were opened.

The first bit about the masks I knew (or intuited, at least). The latter I didn't know. Guess I won't bother with the respirator anymore if it needs to be fitted and the filters need to be different. Not that I ever used it much anyway, I don't often find myself soldering a huge amount at a time.

[eth0s]

Trawling through several medical and industrial databases I have access to through school. Can't find any information about lead fumes from solder, but there's tons of data out there on the toxicity of the flux in the solder fumes. This leads me to believe that there is no correlation between the use of lead-containing solder and increased lead content in the body. However, as Mkawa and Grendel say, that still doesn't make the fumes any safer.

What seems to be a good summary of this conversation: Soldering with, for example, 60/40 solder won't cause plumbism (lead poisoning), but the fumes still aren't safe. For long periods of solder work, wear a mask and work in a well-ventilated area.

Additional point of interest to eth0s: plumbism doesn't necessarily manifest as neurological problems. It can also affect blood pressure, among other things. It does tend to manifest primarily as mental impairment in developing children. Not sure about the precise age range defined as "developing children" in the article I read though -- some sources would keep that label until brain development is complete, which isn't until the 20s at the earliest.

Yeah, I'm an attorney, and lead-poisoning is devastating for the human brain as it develops.  Especially between ages of 0 to 8.  But even after that stage, lead poisoning is bad for all human brains.  Or animal brains.  The worst case of heavy metal poisoning that I've ever seen was about 15 years ago, when I worked for a law firm, in a lawsuit involving workers who welded with manganese rods.  The levels of manganese in their brains was beyond abhorrent.  They all had significant cognitive deficits.  But they had been welding for years, if not a decade.  The makers of the manganese rods actually tried to defend the case by saying manganese is an essential nutrient for the human body!  They will say or do anything to make money.  Please remember that, any time somebody tells you there are "safe" levels of lead ingestion, or manganese poisoning.

@mkawa:  I guess I should have realized that Lead can't vaporize at soldering temperatures.  But, Lead is still dangerous if ingested.  That part is still true. 

[Melvang]

Yeah in the grand scheme of things it isn't really something to worry about at the level that we do as hobbyists.  Now someone that does production soldering, or rework with leaded solder might have a case but even then the inhalation isn't much of an issue.  Most of the issue there would be from direct handling. 

As far as the fit test that is required just because OSHA is required being on the job and what not.  Neither the fit test nor the physical is required to buy one but if you want to wear one, it can't hurt.  But if you are going to spend the money on one get a fit test and buy the proper size.  Remeber also this means no facial hair as that will greatly degrade the quality of the seal with your face, and render the respirator essentially useless.

Here is a link for different filters and pricing
http://www.uline.com/BL_1093/Respirator-Accessories

[user 18]

@Eth0s

In extreme cases obviously pretty much the whole spectrum of symptoms would show up. All I was saying is that neurological problems won't always be the first symptom to show. I suppose we're on the same page there

Correct me if I'm wrong, as my experience in chemistry is quite limited, but I didn't think manganese was considered a heavy metal -- IIRC, heavy metals are heavy metallic elements, and heavy elements are things heavier than Iron. Could be totally wrong there. Not disputing its toxicity though.

What's considered a safe level is relative, and based on timescales. The topic of timescales and their effect on definitions was covered heavily for me in a recent course. If, for instance, the LD50 of a compound is 0.5mg, and you're exposed to 10ug once, but never again, 10ug would generally be considered a safe dose. If you're exposed to the same 10ug every day for 20+ years, that's definitely not a safe dose. Same concept as with radiation exposure for people who work in radiology labs or work with radioactive materials in research labs.

@Melvang

I was just using one of my dad's that he bought for working with insulation when he was insulating our attic. We have the same facial structure and such. I've used it all of once, so I'm not particularly worried about needing one in the future. If I end up doing a ton of soldering work for whatever reason, I'll look into it.

Regarding facial hair, nobody in my family has been able to effectively grow any, so I haven't even tried

[mkawa]

lead is absolutely still dangerous if ingested or absorbed via mucosal tissue, and what you said about lend tending to collect in the bones is true. it collects first in lipid tissue (fat), and eventually makes its way into the bones, but regardless of where it ends up, the half-life of lead in the body is in the years to decades. don't get leaded solder on your mouth, nose, etc; clean your hands after soldering, and if you have breaks in the skin on your hands, be safe and wear disposable gloves. there is NO safe level of exposure to lead.

and flux fumes vary in toxicity, but ARE TOXIC when inhaled. inhaling anything but room air presents a difficulty for your lungs, which must either pass the material into the blood stream to metabolize it or expel is mechanically. one of the reasons i built air cleaners out of flat rate boxes was to show everyone that it takes very little effort to direct solder fumes away from your lungs and into a scrubbing material. a visit to the pet store or aquarium supplies store, a 12v pc fan, a free cardboard box and some tape is literally all you need. and keep in mind that the accumulation of material can cause highly delayed problems. the alveoli in your lungs put up a fight before malfunctioning, but with with small particles of an insoluble material like flux fumes, they will eventually have to face the music. emphysema is not limited to smokers. emphysema is any condition in which lung efficiency is impeded over a long period of time. the physical symptoms, wheezing, difficulty breathing, and the characteristic muscular formations that develop from trying to breath can take years to show up.

don't breathe in particulate fumes people!

[mkawa]

Mn is a transition metal and generally considered a heavy metal. the definition is loose for many non-transition metals, but transition metals are generally inclusively in the set of heavy metals due to their toxicity

http://en.wikipedia.org/wiki/Heavy_metal_(chemistry)

[user 18]

Mn is a transition metal and generally considered a heavy metal. the definition is loose for many non-transition metals, but transition metals are generally inclusively in the set of heavy metals due to their toxicity

http://en.wikipedia.org/wiki/Heavy_metal_(chemistry)

Ah, thanks for clearing that up.

[phoenix1234]

Thank you guys for expanding our knowledge. 

Update 11/05/2014:
After I received the G80-8100 (M- Manufactured in 2000) from this great finds
http://geekhack.org/index.php?topic=57152.0

I tried to do the comparison between type of solder. Plus I also tried to see how many times soldering/desoldering the G80-8100 PCB eyelets can bear before it broken


1 and 2: Default Cherry
3: Kester 63/37
4: Multicore 63 37
5: Asahi 63 37
6: Asahi 60 40
7: Asahi Sn 99.3% Cu 0.7% (+ extra flux)
8: Default Cherry
9 and 10: Cherry PCB eyelets after 7 times of soldering/desoldering
11: Asahi Sn 96.5% Ag 3.5%
12: Asahi Sn 99.3% Cu 0.7% (no flux)
13: Spackle M705 Sn/Ag3.0/Cu0.5 (+ extra flux)
14: Default Cherry

Some highlighted points:

Kester/Multicore/Asahi 63/37 have identical appearance.
Asahi 60/40 is a bit darker but it is hard to be noticed.
Asahi Sn 99.3% Cu 0.7% with flux is shinier than Asahi Sn 99.3% Cu 0.7% with no flux.
Spackle M705 Sn/Ag3.0/Cu0.5 is the slowest speed of wetting. It flows very flow comparing to the rest.
All lead-free solders is less shiny than the lead solder. It has white colour closer to tin material.