Dear Kirk,
Before anyone panics about using all the available Bismuth in large tonnage
ammunition applications (e.g. 150,000 t per year) it should be said that Bi
use is only a small percentage of the non-toxic shotgun market - which in
itself is only a small percentage of the total ammunition market.
kay
+++++ Visit our lead-free.org website +++++
ITRI Ltd, Kingston Lane, Uxbridge, Middx, UK, UB8 3PJ
tel: +44 (0)1895 272406 fax: +44 (0)1895 251841
email: [log in to unmask] www.itri.co.uk and www.lead-free.org
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Kirk D Mueller
Sent: 17 September 1999 18:33
To: [log in to unmask]
Subject: Re: [LF] IPC review September 99 - Antimony and Bismuth in
-Free Solders
As a side note on Bismuth. The commercial shotgun ammunition industry
has
switched over to Bismuth as a replacement for lead shot.
Kirk Mueller
[log in to unmask]
Raytheon Systems Co.
El Segundo, CA 90245
Alan Rae <[log in to unmask]> on 09/15/99 09:28:40 AM
Please respond to "Leadfree Electronics Assembly E-Mail Forum."
<[log in to unmask]>; Please respond to [log in to unmask]
To: [log in to unmask]
cc: (bcc: Kirk D Mueller/RWS/Raytheon/US)
Subject: [LF] IPC review September 99 - Antimony and Bismuth in Lead-Free
Solders
"Filling up on unleaded"
Coming originally to this forum from the metals side - I worked for 4 years
in
the antimony business in the '80's- I'd just like to add some perspectives
on
the use of antimony and bismuth based on some of the comments I keep seeing
in
articles on lead-free solder including the above saying that they're "toxic"
or
"unavailable".
Concerns are being raised about the toxicity and availability of these
materials
and I'm not sure they're well founded. By the way, my employer and I are
not
involved except in the periphery of the antimony or bismuth business so I
have
no commercial ax to grind. If customers want alloys containing these
materials
we can supply them; if they don't want them, that's no problem either. The
following are my personal perceptions so they're obviously open to comment,
debate, interpretation, correction etc.
Bismuth first. Bismuth is indeed a by-product of lead refining but I do not
see
lead consumption falling because of the increasing use of lead-acid
batteries.
These account for about 80% of the use of lead and have a recycle ratio near
100%. As we move to hybrid and electric vehicles I don't see a technology
to
immediately replace these batteries and I see a growing lead consumption.
So
bismuth should not be in short supply. Apparently the major commercial use
of
bismuth is as compounds such as bismuth salicylate which are used in large
quantities as stomach medicine (by those worried about the switch to
lead-free?). In fact it's the major use of bismuth. So - why are we
worrying
about its toxicity?
Now antimony, which is a by-product of not only lead but also gold and other
metal production. Again, no shortage; a continued use in lead-acid batteries
as
a plate stiffener and the major use as a flame retardant, especially in PVC
in
your house, office and automobile. Remembering my chemistry, I believe
antimony
is one of those funny amphoteric oxides which are insoluble in strong acid
(i.e.
stomach acid) but are quite soluble in neutral pH e.g. in ground water
leachability tests. There are concerns, particularly in Europe, on the
inhalation of the oxides. But antimony is used widely in our daily lives
with
no apparent ill effects that I am aware of - so why are we so worried about
its
toxicity also?
In both cases, if you are aware of any data that prove the above to be
wrong,
please let me know.
All metals or their compounds can be labelled toxic. In our circuit board
materials, many tin, silver and copper componds are toxic, if not to humans,
to
fish, invertebrates, vegetation or other life forms; glass fibers aren't
great
to inhale(I've tried) and the last pot of epoxy I used in airplane
construction
came with a MSDS that looked as if it had been written by Tolstoy! Copper
oxide
is used as a wood preservative. Tin organics can be used in antifouling
paints.
Remember salt that is essential to your life is made from chlorine, once
used as
poison gas, and sodium, a spontaneously-flammable metal. And that's before
we
get into the materials used in semiconductor processing!
I think we need to be very careful before we unwittingly damn any of our
technology choices in public because of toxicity or availability - and get
the
facts. I'm not saying antimony or bismuth are safe - but let's make a
realistic
assessment based on their actual life cycle before we label them "toxic" or
"unavailable". Absolutely we need to be good stewards of the environment but
let's not paint ourselves into a corner by eliminating useful technology
needlessly. If metals are deemed to be toxic, isn't a takeback and reclaim
program a more practical solution than banning them needlessly? Even the
electric toothbrush I bought this weekend has a clearly explained takeback
mechanism for the Ni-Cd batteries that are hermetically sealed in plastic!
As I said, let's get the facts. The move to lead-free has so much momentum
it's
probably unstoppable. With other critical materials that are less in the
public
eye let's get a proper environmental assessment. Let's not make sweeping
comments in widely read papers before we've done that. They will be read
and
people will naturally say hmmm - here's a material to add to our list to be
banned.......
I hope you find these comments useful and would welcome your feedback.
_________________
Alan Rae
Director of Technology
Cookson Electronics Inc.
225 Foxborough Blvd. Suite 150
Foxborough MA 02035
USA
[log in to unmask]
Phone: (508) 541-5843
Fax: (508) 541-5877
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Please visit IPC's Center for Lead-Free Electronics Assembly
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For technical support contact Gayatri Sardeshpande [log in to unmask] or
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IPCWorks -October 25-28 featuring an International Summit on Lead-Free Electronic
Assemblies.
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(http://www.leadfree.org ) for additional information.
For technical support contact Gayatri Sardeshpande [log in to unmask] or 847-790-5365.
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