Fun with Lead-Free soldering

[Chris Carlen]

Talk about jumping out of the frying pan into the fire. One of the
explanations of the name for Antimony is 'anti-monk'---because it killed
monks who worked with it. Lead is positively benign compared to Sb.

Talk about a coincidence -- I opened my Merck Index to look up the LD50
for lead, and the first page (out of over 2000) opened was lead!!!

Interestingly, soluble antimony vs. lead compounds appear to be more
acutely toxic by weight:

antimony potassium tartrate: LD50 = 55-65 mg/kg in mice

lead acetate: LD50 = 200 mg/kg in rats

Perhaps rats are a bit more robust than mice

However it is lead that is a far greater chronic toxin with lead
poisoning considered to be serious in children at 0.44 ppm or 44ug/dl
blood concentrations.

http://www.aclppp.org/bll.shtml

Lead is also considered to be a carcinogen, and antimony not, or at
least not as well established as Pb.

Note that Sn95Sb5 is the solder alloy now approved for potable water
systems, whereas all Pb solders are banned from such use.

So the 0.5% Sb in CASTIN doesn't concern me much.


Some more interesting stories and info about carcinogenity:

http://www.intox.org/databank/documents/chemical/antxide/ukpid38.htm

 

[Jeff]

I got a roll of Kester SAC305 alloy 0.031" no-clean flux cored wire
solder.


*NO CLEAN* Gag-gag-gag. Throw it away. I've seen too many problems
caused by "noclean" flux. Get some good water clean flux stuff.

Tested it out by soldering a DIP and some wires to a PCB and
also by tinning some wire. The tinning went a lot smoother (wetted
slightly under the skin, not just the tip near the iron) when some
additional rosin flux liquid was applied.

That's one of the problems with the "no clean" stuff. It isn't very good
flux.

[...]
The point is that technician work areas are also used for eating, as we
don't have separate offices and labs like scientists.

My office is my lab. I eat in the lunch room.

(My emulator has to be hooked to the proto type and to a PC. This either
means I need two PCs or have the lab in the office. They knocked out a
wall to make the space large enough.)

But if we can't
work with chemicals in our work areas, that sure cuts down on the amount
of work we can do.

If chemicals are needed to clean a PCB, I take the PCB to the fume hooded
PCB cleaning area. I don't bring those chemicals into the office/lab.

[...]
If the automated assembly industry will definitely move to lead-free,
what about all the hand soldering that is still done? It seems it is
easier to get automated processes to work well with these solders, but
hand soldering will just never be the same. Is the EU banning only
commercial products from Pb solder processes, or will lead solder be
simply unavailable, such as to hobbyists and engineers doing R&D work?

I think a more expensive solder for hand work will become available.
Chances are it will be an alloy of plutonium, goofium and unsidaisium and
hence be as toxic as all get out but it will be lead free.

I had a spec sheet on my desk for some lead free. It was bragging about a
lower then most other lead free solder melting temps, and I think reasonable
wetting. I was wondering what they used to lower the melting point, since
the usual alternatives are ether expensive (indium), or much more toxic then
lead. Reading the spec sheet it was alloyed with a little cadmium.

Well RoHS says you can't use that either !

Next .... ?

Graham

It's allowed in small concentrations.

IIRC, RoHS allows a 0.2% by weight limit for lead to be concidered lead
free.

 

[Adrian Tuddenham]

Hello Jim,


Here in CA they are replacing it with Ethanol. Which means we will still
have boutique gas at elevated prices.

I don't think politicians will ever understand that you have to have a
reliable fast train system to drag people away from their cars. I'd use
the train to the Bay Area but not right now where you never know when it
really arrives. And that thing crawls like a snail compared to the
trains overseas. So, everybody hops into their cars or a rental to do
the 2-3 hour trip.

At least tramway (streetcar) systems are opening at a spectacular rate
in the US.

Over here (UK) every single tram proposal is fought tooth-and-nail by
the bus lobby who have been promising the politicians that
pollution-free buses are just around the corner for deacades. The
politicans keep falling for it time and again and the tramway projects
keep on being shelved while they wait for deliveries of new buses -
which are no better than the old ones.

They've even had the cheek to name a diesel bus with a fibreglass
replica tram body a "Streetcar" - and the local tram plans have been set
back another five years whilst the Local Councillors investigate it.

 

[Chris Carlen]

YUK! Proper anti-static and QC procedures must not exist in your shop.

Shop? It's a lab. Nothing is production oriented.

I began taking ESD seriously a few years ago, and at least use wrist
straps and grounded table mats, as well as designing-in features for ESD
tolerance for my gadgets. I am still laughed at by my fellow
technologists for the most part for considering ESD to be a worthwhile
hazard to spend effort mitigating.


Good day!

--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.

 

[Chris Carlen]

Hello Chris,


Eating at the lab desk? That sure doesn't sound like a proper work place
procedure. I mostly work in medical electronics. If the FDA ever saw
someone have a burger at a work station I bet they'd lock down the whole
company. Actually I am pretty sure they would, and for good reasons.

Heh heh, well we are the government, so we make the rules. Seriously
though, as I explained there are labs, where food is not permitted.
There are "technician work areas" outside the labs, where food is
permitted and so is soldering, just not on the same table. Then there
are offices. We techs don't get offices, nor do we get extra facilities
for soldering. Thus, if this really goes forward, it will create
headaches as rooms will have to be allocated for soldering. Or it could
be done in labs, but they are already fairly packed. Fortunately my
department has an extra "electronics storage and assembly room" that
I've been setting up for a while.

Even here in my consulting practice there is strictly no eating in
office or lab areas. Never.

Even in offices? Jeez.

Other than that, what about the chemicals in the ketchup on a burger?

They will be banned!

;-)

Good day!


--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.

 

[Chris Carlen]

*NO CLEAN* Gag-gag-gag. Throw it away. I've seen too many problems
caused by "noclean" flux. Get some good water clean flux stuff.

I don't like no-clean, but that's all Kester offered with SAC alloy. I
will be getting some AIM SAC or CASTIN wire with RMA.

Have you ever tried water-clean flux in cored wire?

That's one of the problems with the "no clean" stuff. It isn't very good
flux.

Perhaps you are right.



Good day!




--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.

 

[Jim Yanik]

Shop? It's a lab. Nothing is production oriented.

A "lab" is still a "shop",short for "workshop".
Eating should not be allowed in either a lab or a shop.

When I worked in the USAF Precision Measurement Equipment Lab(PMEL),our
"lab" was cleaner than the base hospital.We entered through an airlock and
trod across a "sticky mat" to keep dirt out.Friday afternoon was clean-up
period,where we damp-mopped the entire place,shelves,floors,anywhere dust
would accumulate.And the air was tested to measure the number of dust
particles per square cm.It was temperature and humidity
controlled,monitored with chart recorders.

I began taking ESD seriously a few years ago, and at least use wrist
straps and grounded table mats, as well as designing-in features for ESD
tolerance for my gadgets. I am still laughed at by my fellow
technologists for the most part for considering ESD to be a worthwhile
hazard to spend effort mitigating.


Good day!

What do you wrap your food in? What is it carried in?
Are you bringing plastic bags or non-anti-static plastic boxes into your
"anti-static" area?

 

[Pooh Bear]

Shop? It's a lab. Nothing is production oriented.

I began taking ESD seriously a few years ago, and at least use wrist
straps and grounded table mats, as well as designing-in features for ESD
tolerance for my gadgets. I am still laughed at by my fellow
technologists for the most part for considering ESD to be a worthwhile
hazard to spend effort mitigating.

Doesn't say much for the supposed 'technologists' !

Graham

 

[Joerg]

Hello Chris,

Heh heh, well we are the government, so we make the rules. ...

Usually only until something happens. Then a few decision makers are
going to be in hot water.

Even in offices? Jeez.

No. There are lab areas, office areas and eating areas. I bet my clients
wouldn't appreciate a grease stain on a schematic ;-)

Regards, Joerg

 

[Chris Jones]

Pooh Bear wrote:

[...]

Incidentally, I reckon that bio-fuel is the long term answer to oil
shortage /
demand / price issues, not to mention reducing greenhouse gases. I gather
that there are a number of pilot schemes that are actually fairly big now
that are showing interesting results. Ford is selling a version of its
Focus in Sweden for example that'll run an a 50/50 mix of straight
petroleum fuel and alcohol. The alcohol is made by 'brewing' timber waste.
For some reason I don't yet understand, unlike Brazil's gasohol, this mix
actually provides 10% *more* power than straight unleaded ! Sounds great
to me. The hydrogen fuel idea is plain bonkers in comparison.

Graham

My car runs on biodiesel made from waste cooking oil. I read somewhere that
if all the present vegetable oil production were used as fuel then that
would only displace 10% or so of the diesel use but I don't know if that is
true. According to my measurements, my car does on average 4.4
litres/100km (53 MPG US) It is unmodified. Maybe if there were less cars
around that can only do 20MPG then there would be less difficulty in
finding enough biodiesel to power them.

I think people should stop trying to make hydrogen cars and only start again
when (and if) they've figured out how to make hydrogen (without nuclear or
fossil fuel).

Chris

 

[Pooh Bear]

Hello Chris,


Usually only until something happens. Then a few decision makers are
going to be in hot water.


No. There are lab areas, office areas and eating areas. I bet my clients
wouldn't appreciate a grease stain on a schematic ;-)

An interesting point. I can only recall a few employers or clients where
there was a canteen and only one with a dedicated 'kitchen' of any size.

I'm entirely used to eating at the desk and it seems commonplace in the UK.

Graham

 

[Joerg]

Hello Graham,

An interesting point. I can only recall a few employers or clients where
there was a canteen and only one with a dedicated 'kitchen' of any size.

That surprises me. With all this ISO stuff we had to designate all
areas. Tape lines on the floors and the whole nine yards. You can't even
store anything in an area that isn't a dedicated materials storage
location. And here I thought this whole ISO biz originated in Europe
where all these other wonderful bureaucratic hurdles come from, like
ROHS or WEEE.

I'm entirely used to eating at the desk and it seems commonplace in the UK.

In the US it's more regulated. There is also occupational safety and
health (OSHA). I bet if they caught several people eating in a tech or
production area they would not be too enthused.

Regards, Joerg

 

[Jim Yanik]

Hello Chris,


Usually only until something happens. Then a few decision makers are
going to be in hot water.


No. There are lab areas, office areas and eating areas. I bet my clients
wouldn't appreciate a grease stain on a schematic ;-)

Regards, Joerg

I hate it when the can of Coke spills all over everything.....
and crumbs in the keyboard....then the ants move in....

B-)

 

[Ken Smith]

I think people should stop trying to make hydrogen cars and only start again
when (and if) they've figured out how to make hydrogen (without nuclear or
fossil fuel).

Gerbil spins wheel which turns generator which sends power to a pickle jar
with water in it. See the pretty bubbles?

Actually solar input would be the best if we could make it work well.

 

[mc]

Other than that, what about the chemicals in the ketchup on a burger?

They will be banned!

Pity. They're probably pretty good as flux!

 

[Ian]

Gerbil spins wheel which turns generator which sends power to a pickle jar
with water in it. See the pretty bubbles?

Actually solar input would be the best if we could make it work well.

It is not just the making of the hydrogen, but also the storage that is
a huge problem.

Regards
Ian

 

[Ken Smith]

It is not just the making of the hydrogen, but also the storage that is
a huge problem.

Each carbon atom will attach to 4 hydrogen atoms. The resulting material
can be stored by compressing it and transports well through pipes. If you
use a chain of 8 carbon atoms, you can store 18 hydrogen atoms per each.
This would make the idea fuel for automotive and portable applications.

 

[Terry Given]

Shop? It's a lab. Nothing is production oriented.

you do want it to work though, right ?

I began taking ESD seriously a few years ago, and at least use wrist
straps and grounded table mats, as well as designing-in features for ESD
tolerance for my gadgets. I am still laughed at by my fellow
technologists for the most part for considering ESD to be a worthwhile
hazard to spend effort mitigating.

I often come across anti-ESD attitudes. Usually from people with a
rather limited understanding of the potential effects of ESD, the worst
of which is a noticeable reduction in lifetime - IOW failures that crop
up after some time, rather than outright deaths.

I once had a holiday job (1990) at a place that used a ceramic windowed
87C552. In one week my boss killed 10 of these parts ($200 each) because
he was in the habit of carrying them to and from the programmer (in a
carpeted office) in his hand. There were straps & mats at either end,
along with bags, he just chose not to use them.

I have also had a smps controller expire due to static - boss gave a
show-and-tell to some visiting guests, picked up my fully working smps
and waved it around for about 10 minutes, before passing it to the group
to be handled. I came back a few hours later, went to do some work only
to discover it had shat itself. Luckily I soft-started the smps (provide
external startup supply, check waveforms, slowly ramp up impedance
limited HV supply etc), so found the problem, which was the UC3842
output stage, shorted *on*

Had I just flicked the switch, ka-boom.

static damage falls in the general category of "totally unnecessary
mistakes to make"

Good day!

Cheers
Terry

 

[Terry Given]

Talk about a coincidence -- I opened my Merck Index to look up the LD50
for lead, and the first page (out of over 2000) opened was lead!!!

Interestingly, soluble antimony vs. lead compounds appear to be more
acutely toxic by weight:

antimony potassium tartrate: LD50 = 55-65 mg/kg in mice

lead acetate: LD50 = 200 mg/kg in rats

Perhaps rats are a bit more robust than mice

LD50 is basically useless, for pretty much that reason.

 

[Richard Henry]

I often come across anti-ESD attitudes. Usually from people with a
rather limited understanding of the potential effects of ESD, the worst
of which is a noticeable reduction in lifetime - IOW failures that crop
up after some time, rather than outright deaths.

I once had a holiday job (1990) at a place that used a ceramic windowed
87C552. In one week my boss killed 10 of these parts ($200 each) because
he was in the habit of carrying them to and from the programmer (in a
carpeted office) in his hand. There were straps & mats at either end,
along with bags, he just chose not to use them.

I have also had a smps controller expire due to static - boss gave a
show-and-tell to some visiting guests, picked up my fully working smps
and waved it around for about 10 minutes, before passing it to the group
to be handled. I came back a few hours later, went to do some work only
to discover it had shat itself. Luckily I soft-started the smps (provide
external startup supply, check waveforms, slowly ramp up impedance
limited HV supply etc), so found the problem, which was the UC3842
output stage, shorted *on*

Had I just flicked the switch, ka-boom.

static damage falls in the general category of "totally unnecessary
mistakes to make"

While going to college the second time, I worked as a production test tech
in the era of discrete TTL devices, but before much recognition was given to
ESD control. After a while, I began to recognize a common type of failure,
in which a 74LS04 inverter would got sort of half-on. This typically
occurred where the output in question was routed directly to a card I/O
connection finger. I found my time was most efficiently used by getting the
assembler to replace all the 04's that were connected off-board on
assemblies that had that problem.

Note: after removing the baddies and soldering on the new parts, the
assembler would clean the board in an ultrasonic tank full of TCE, then
bring it to me still dripping.