Dear Lee and all:
I agree that there has been a great deal of concern regarding antimony.
However, there also has been much confusion. Confusion has also arisen
regarding the appropriate test methodologies and standards regarding
landfill disposal. I will attempt to clarify some of this below (sorry for
the lengthy message, but this is a lengthy topic).
First of all, it is not appropriate to measure the Toxicity Characteristics
Leaching Procedure (TCLP) results of certain lead-free solders against
drinking water standards, rather than against the more appropriate effluent
waste water (NPDS) standards. Effluent wastewater from the TCLP test
results should be considered in the context of solid landfills, and should
not be held to the drinking water standard.
Drinking water has justifiably been assigned the most stringent standards of
all classes of water. As an aside, the standards are so strict, in fact,
that if one was to run drinking water directly out of the tap through a
drain and collect it for testing, it is likely that the water would fail to
meet applicable standards. Wastewater from soldering operations is passed
through waste streams to solid landfills, and this water will not enter
drinking water systems. Therefore, drinking water standards do not pertain
to effluent wastewater standards whatsoever.
Independent laboratories have tested tin-copper, tin-silver, and
tin-silver-copper-antimony alloys to the TCLP (solid waste disposal)
standards. All three of these alloys have proven to have no detectable
quantities of the elements stated in the article's test results. In fact,
U.S. Federal TCLP testing does not even require that antimony be tested for.
This underscores the fact that each of the alloys can be safely disposed of
as solid waste. Copies of the results of these tests are available for your
review upon request.
Drinking water and effluent wastewater have nothing to do with each other,
as far as acceptable metallic levels are concerned. Furthermore, it should
be noted that when tested to the appropriate standards for effluent waste,
most lead-free alloys, including the aforementioned, will pass all pertinent
TCLP testing.
Regarding antimony itself, this element has been used for years in solders
and is acceptable as an impurity in tin/lead solders up to 0.5% per IPC
standards. As Mr. Langeveld states, the oxide form of antimony, and not
antimony itself, is cause for concern. Confusion regarding the toxicity of
antimony has developed as a result of the outlawing of antimony trioxide.
Antimony trioxide, used as a fire retardant, is toxic at .5 mg per cubic
meter of air. However, antimony trioxide cannot be formed during soldering
or reclamation processes. This is quite similar to other "safe" elements-
tin Butylate is quite toxic, yet tin in solders is considered perfectly
safe.
There is a great deal of data that supports the fact that antimony is not
harmful in terms of its use in a solder. It is interesting to note that,
according to the Agency for Toxic Substances and Disease Registry (ATSDR)
and the EPA, antimony is ranked below zinc, bismuth, copper, and silver (all
of which are constituents of lead-free alloys), as well as lead, in terms of
its potential threat to human health. Perhaps of equal importance, there is
no legislation, past, present or pending, that could prohibit the use of
antimony in a solder.
In the past I have offered to this forum a copy of "A Study of Antimony",
which goes into great detail in describing the true "toxicity" of antimony
and other elements used in solders. Again, if anyone would like a copy of
this please let me know. The study is 7 pages long and emailable; the
supporting document are 150 pages and are available in hard copy format
only.
When looked upon in a circumspect manner and considering the appropriate
effluent disposal guidelines, there is no reason to perceive antimony in
solders as an environmental or human health threat. This being the case, in
the development of these alloys solder companies have ensured that there are
"no undue environmental impact and (these alloys) are safe in their intended
use".
Best regards,
David Suraski
----- Original Message -----
From: "Wilmot, Lee" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, October 09, 2000 9:37 AM
Subject: [LF] Antimony Toxicity
> Is there serious development activity on solder alloys using antimony?
> If so, has anyone done an environmental impact assessment yet? NOTE: Such
> assessments are required for those that subscribe to the 16 principles
> published by the International Chamber of Commerce, known as "The Business
> Charter for Sustainable Development". Examples, #5 PRIOR ASSESSMENT -
"To
> assess environmental impacts before starting a new activity or project
..."
> and #6 PRODUCTS and SERVICES - "To develop and provide products or
services
> that have no undue environmental impact and are saf in their intended use,
> that are efficient in their consumption of energy and natural resources,
and
> that can be recycled, reused, or disposed of safely."
>
> Attendees at the 1999 Int'l LF Forum in Minneapolis, MN heard Edwin
Smith's
> paper on Environmental Impacts and Toxicity of Lead Free Solders" in which
> 95 tin, 5 antimony solder was tested using five different leach methods (3
> US (TCLP, SPLP and STLC), one European (PrEN) and one Japan (JST-13)).
> Conclusions >> "The leaching levels are approximately 10,000 times the
> maximum allowable in drinking water. The 95Tin-5Antimony allow studied
> leached above the regulatory limit in every physical form and in all leach
> methods." (Forms tested were 3/8" spheres and -315,+500 solder paste.
Based
> on this testing, I dispute the comment below that the toxicity of Sb is
> related to the oxide form (unless antimony oxide is water soluble).
Smith's
> sample preparation alloyed the samples under oxygen free conditions.
>
> So, I ask again, is there serious development activity on solder alloys
> using antimony?
> Are LF solder alloy developers following the ICC principles for
sustainable
> development?
> Lee Wilmot, Sanmina Corp 603/896-2424
>
> -----Original Message-----
> From: <Peer Langeveld> [mailto:[log in to unmask]]
> Sent: Monday, October 09, 2000 4:54 AM
> To: [log in to unmask]
> Subject: Re: [LF] Alloy question
>
> As a member of the IDEALS consortium and experienced with
> SnAg3.8Cu0.7Sb0.25, I can say that the melting point is still 217dC and
> there is no lower cost than without Sb. The low cycle fatigue is about
equal
> to that of SnPb, be it that the first signs of fatigue showed up later.
See
> the proceedings in EGG Berlin and IPC Works 2000.
> The toxity of Sb is related to the oxide form, that can be produced while
> incinerated at temperatures over 615dC
>
> [log in to unmask]@[log in to unmask] on 2000-10-04 00:04:02
> Please respond to [log in to unmask]@SMTP
> Sent by: [log in to unmask]
> To: [log in to unmask]@SMTP
> cc:
> Subject: [LF] Alloy question
> Classification:
>
> What does anyone know about the Sn/Ag/Cu/Sb alloy? From what I read,
> compared to Sn/Ag/Cu, it has a lower melting point, lower cost, and yet
> very similar physical properties. I know there is a toxicity concern,
> but, once again, according to what I read, a level of .5% is allowable.
> Perhaps it will be phased out eventually much like lead is now. Any
> experiences or thoughts on this?
>
> Thanks in advance for your help,
> Kirk
>
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