Marc:
Note that small concentrations of bismuth can induce hot shortness in copper
alloys (this is the tearing or separation of an ingot of copper that is
being hot rolled or hot forged). The technology to remove Bi from a copper
melt does not exist. Therefore the leadframe materials that are coated with
SnBi, as well as any in process scrap, will have zero recycling value and
will need to be separated from other valuable copper scrap sources. This is
the primary reason we do not endorse Bi containing coatings for lead free.
Bob Hilty
Tyco Electronics
-----Original Message-----
From: Dittes Marc (CPD AIT PGP) [mailto:
Sent: Tuesday, October 09, 2001 10:16 AM
To: [log in to unmask]
Subject: [LF] AW: [LF] Bismuth
Maybe also someone from Ericsson will comment this statement, but if not,
please be informed that Bi is not included in the "restricted list" because
of its toxicity but because of recycling issues, which I (due to the
information I have from recyclers and copper miners) do not share. Bi from
SnBi-plating of leadframe components for example will result in a 10 ppm
level at its maximum related to the whole PCB and will not affect recycling.
The introduction of eutectic BiSn solder may cause an price impact for
recycling issues. But this must be calculated individually taking into
account that soldering at low temperature results in the option of using low
price materials and processes, which might overweigh the recycling cost
adder.
Best regards,
Marc Dittes
-----Ursprüngliche Nachricht-----
Von: Charles Dolci [mailto:[log in to unmask]]
Gesendet am: Montag, 8. Oktober 2001 22:58
An: [log in to unmask]
Betreff: [LF] Bismuth
One of the current lead-free solder options is an alloy of tin/bismuth.
Yet there seems to be some concern about bismuth being a toxic element.
Ericsson, and perhaps others, include bismuth as an element on their
"restricted
list" and ask prospective customers to state if their products contain
bismuth.
If there are Ericsson reps (or others who list bismuth as a chemical of
concern)
on the alias, can they explain the concern over bismuth and if there is a
concern does it make sense for the industry to be substituting one unpopular
element for another?
Charles F. Dolci
Director, Environment, Health & Safety
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