Yes, it looks like that article is referencing the same info found in
the white paper link I provided. Since both links originate from the
same source(smt.pennnet.com), that is understandable.
I look at this method as a way to possibly re-claim tips that are still
in good condition, but just contaminated with Pb. I would NOT want to
make this a standard practice on the production floor, in order to just
re-use the same tips with both processes - too much chance for error.
Archives are available here:
http://www.ipc.org/contentpage.asp?Pageid=4.3
Or under the "knowledge/email forums" tab on the main ipc.org website.
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Hornback, David
Sent: April 21, 2006 10:47 AM
To: [log in to unmask]
Subject: Re: [LF] cross contamination of solder tips with lead solder
Thanks Genny, that is exactly what I was looking for. This SMT magazine
article has similar info.
http://smt.pennnet.com/articles/article_display.cfm?Section=ARTCL&C=Feat
&ARTICLE_ID=252911&KEYWORDS=solder%20tip&p=35
I'll figure out how to search the archives of this list so that I don't
ask too many questions that have been hashed in the past. Dave
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
Sent: Friday, April 21, 2006 8:32 AM
To: [log in to unmask]
Subject: Re: [LF] cross contamination of solder tips with lead solder
Hi David,
I believe the references to the solder rinsing article are the link I
posted about 3 weeks ago. Here it is again.
http://smt.pennnet.com/whitepapers/wp.cfm?id=269
Basically it said that if you took an uncontaminated tip, and tinned it
once with SnPb solder, then wiped that off and tinned it with Pbfree
solder, and then shook off the Pbfree solder, collected and tested it,
it could have up to 10X the allowable Pb content. That was from just a
single tinning operation.
I have been using that as an example in the internal training I have
been giving, for why process control is so important.
Having said that, we will be needing to switch stations back and forth
for quite a while in our company. Being a high mix product company, we
do not have the room to have a completely separate segregated line for
each product group, and each group will have some products switching
sooner than others.
So we are developing procedures and a kit to use to changeover an
assembly station. However, as far as the iron itself, we will be
re-using the actual soldering iron base/controller, and just changing
out the tips, and tip cleaners, and cleaning the holder, and putting up
signage to clearly mark the status of the bench.
We will also use a locked cabinet for the tool kits. One thing to think
about is needing double the kit holders, with 1/2 of them always empty,
and colour code the kit holders. Don't make the holders generic for
both types of tools, or it will be too easy to make a mistake about
which set it is currently holding. So we are looking at making a kit
holder that folds up for low volume storage when empty.
Genny.
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Hornback, David
Sent: April 21, 2006 7:38 AM
To: [log in to unmask]
Subject: Re: [LF] cross contamination of solder tips with lead solder
Thanks, that article might have some of the info I am interested in,
I'll check it out. I received many private messages from folks with the
theme "you must segregate". I assume that as well but would still like
to understand the science behind it. I work in Engineering and my labs
are for development and very little of my product ships to customers. I
am currently headed down the path of separate stations in every lab. I
am in a mixed lead/leadfree environment and expect to be there for some
time.
I will have an auditable process to ensure that we don't ship
contaminated product to destinations that do not allow it.
Dave
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Kane, Amol (349)
Sent: Friday, April 21, 2006 4:20 AM
To: [log in to unmask]
Subject: Re: [LF] cross contamination of solder tips with lead solder
An interesting article regarding this issue in the April 2006 SMT
magazine, read and decide for yourselves! There was also another
(similar) study done by OK International I think? Which seemed to
suggest also that rinsing SnPb tips with SAC "n" times before actual
soldering reduced the SnPb content on the tip to below RoHS levels. We
here are going with separate solder stations with a locked cabinet near
it to store all the "lead-free stuff" once soldering is done. We have
also trained our best SnPb solderers in lead-free hand soldering, so
that there is less chance of mixing solders due to a controlled group of
people handling the soldering process.
Amol Kane
M.S (Industrial Eng.)
Process Engineer
Harvard Custom Manufacturing
941 Route 38 Owego, NY 13827
Phone: (607) 687-7669 x349
[log in to unmask]
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of MA/NY DDave
Sent: Friday, April 21, 2006 12:39 AM
To: [log in to unmask]
Subject: Re: [LF] cross contamination of solder tips with lead
solder
Hi David of Qualcomm, IPC LF Listservers, Hey I like that name David..
<I'm looking for information on how much of an issue cross contamination
of solder tips with lead free solder and sn63 solders will be regarding
Rohs compliance.> < < Our current assumption is that we need separate
solder stations to prevent cross contamination and non-compliance on a
lead free assembly.
Are you aware of any studies done on this issue? If I use a leaded
solder on a solder tip, and then clean and re-wet with lead free solder
on the same tip, how much contamination can occur? Enough to warrant
separate stations?
<I am aware of the reliability issues and am only concerned with Rohs
compliance at this time.>
First my thoughts: Separate solder stations and manufacturing discipline
across management, engineers, down to operators. This is for RoHS safe
sleeping during the night for management. It is called due dilligence
and is listed on the UK's National Weights and Measures Laboratory web
site.
There are some reports in the technical magazines, and I commented on
one of these recently that another LF'r gave us. (I think it was from
our Canadian gal manufacturing engineer, in the Western provinces, who
is great with piles of questions.
The problem I see is that your question is open ended and indicates an
out of process control situation. If they do it they do it, and when
they do it, it happens. Pretty soon you will be soldering with SnPb
since it has nicer working conditions and a nicer presentation after
soldering.
Sorry I can't be of more help.
Yours in Engineering, Dave
YiEngr, MA/NY DDave
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