Yes, should have made it clear that I was talking current accepted
practise, soon to be "traditional" I suppose, but I do appreciate the
points you have made, which perhaps tend to get overlooked in the
search for functioning alloys.
Mike
----- Original Message -----
From: "Alan Rae" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, April 02, 2001 10:49 PM
Subject: Re: [LF] Recycling Solder
> Hi Mike!
>
> There are a number of key points here.
>
> Reclaimed solders indistinguishable in quality from "virgin" tin
based have
> been used successfully for many years in many markets worldwide.
>
> Many of the industrial solder markets e.g. auto heat exchangers or
even
> "came lead" for windows are now lead-free. All consumer solder is
> lead-free. This mean's there is a very rapidly declining "sink" for
high
> lead solder materials.
>
> For the next 15 years most of the recycle stock will be
lead-containing as
> lead-free hasn't started working itself through the life cycle in
bulk, so
> tin will need to be separated from lead. The best economic
technology
> struggles to reduce the lead level in tin cost-effectively below
0.2%.
> Smelting doesn't work and really sophisticated multi-step processes
are
> needed.
>
> Even "virgin tin" has a finite lead content by the way. You can
imagine
> what will happen to tin prices if the recycle circuit material is
removed
> from the equation!
>
> European manufacturers will be obliged to have a significant
recycled
> content in their products. As solder is about 7% by weight of the
circuit
> board and as about 70% is not practical to recycle using existing
> technology (brominated epoxy and glass fiber), it will be important
to them
> to use recycled solder.
>
> So what do we do? Let's really work on recycling more solder and be
> prudent when we set limits and specifications - let's include the
recyclers
> in the loop or we might get into a cost-prohibitive situation. In
> particular, taking the lead limit below 0.2% will really pinch the
tin
> supply for the foreseeable (15 year+) future. In addition if
manufacturers
> are unable to dispose of dross, containers etc. to solder reclaimers
as
> they do now, there will be another significant cost increase.
>
> Alan Rae
> VP Technology
> Cookson Electronics
> 225 Foxborough Blvd. Suite 150
> Foxborough MA 02035
> 508 541 5843 fax 508 541 5871
> 617 803 7712 cell
>
>
>
> Mike Fenner
> <[log in to unmask] To: [log in to unmask]
> o.uk> cc:
> Sent by: Subject: Re: [LF]
Recycling Solder
> Leadfree
> <Leadfree@IPC
> .ORG>
>
>
> 04/02/01
> 01:24 PM
> Please
> respond to
> Mike Fenner
>
>
>
>
>
>
> You are right, but you need to pay close attention to the semantics
> here: "virgin grade" and "virgin metal" are not quite the same
thing.
> There is also a distinction between recycled and refined.
>
> I have always understood "virgin grade" to mean metal that is as
pure
> as freshly mined i.e. never been used "virgin metal". Virgin grade
> can be achieved by refining recycled metal.
>
> So far as I know all suppliers use virgin grade, with most
electronic
> grade suppliers also claiming further unique refining/processing
> in-house.
>
> After use electronic grade material is still pure enough for non
> electronic use and so can be recycled as a lesser grade, and this
> itself can then be recycled, [with some alloying additions and
> corrections] for another less demanding application and so on till
> there is nowhere to go except back to a big smelting company who
will
> clean the material right up by a true refining process to restart
the
> cycle.
>
> Mike
>
>
> ----- Original Message -----
> From: "Brian Ellis" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, April 02, 2001 5:20 PM
> Subject: Re: [LF] Recycling Solder
>
>
> > Malcolm
> >
> > Yes, I agree with you that it is theoretically possible to purify
> > recycled solder back to Grade A levels, and that to extract tin
from
> > cassiterite requires purification to remove some other metals.
> However,
> > it would seem economically more difficult to do so, in view of the
> great
> > mix of different impurities (metals and non-metals) in recovered
> solder,
> > compared with the few in ore. Also, the major solder producers
have
> > extolled the virtues of virgin-grade solder for so many years that
> users
> > will take a long time before they accept recycled solder which has
> > traditionally been considered as OK for plumbers but not for us.
> >
> > Brian
> >
> > Alco-Met wrote:
> > >
> > > Brian Ellis wrote :
> > >
> > > >
> > > > I agree that recycling would be the ideal, but I wonder to
what
> extent
> > > > the electronics industry would accept non-virgin grade solder,
> > > > especially as requirements for fine-line SMD work can be very
> critical?
> > > > I don't believe this problem would arise with most other
> applications
> > > > for solder, representing about 50% of the consumption, but I
do
> believe
> > > > that we shall always require Grade A solder, hence mostly from
> freshly
> > > > smelted tin. (Solders and Soldering, Manko, p. 46)
> > >
> > > Since I applaud Brians efforts to discuss lead free issues
> rationally, I
> > > would like to clear up a commonly held metallurgical
misconception
> that the
> > > above text implies ( whilst declaring in advance my interest as
> being a
> > > supplier of solder ).
> > >
> > > Following smelting ( the process by which metal oxides are
reduced
> to
> > > metal ) there is invariably need for the smelter to refine its
> metal output
> > > to produce the Grade A or fresh (sic) tin.
> > >
> > > Such refining process ( usually electro refining or pyro
> metallurgical
> > > techniques ) can also be undertaken by recyclers so that the
> resulting
> > > solder has contaminant levels which meet or indeed exceed those
> which can be
> > > achieved using Grade A tin.
> > >
> > > So, subject to the laws of economics, the entire tin lead
> requirement of the
> > > electronics industry could be met from recycled sources.
> > >
> > > Perhaps this would be a more worthwhile development if we are
> truly
> > > interested in "joined up" environmental protection.
> > >
> > > Malcolm Noble
> > > Alco-Met (Solders) Ltd
>
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