Werner I think Yusuf's question is about dissolution of Cu into solder pots
from PCBs. 
He describes how Cu content may be reduced in Sn63 by cooling the pot down a
skimming off the higher Cu zone formed. Then he is asking if there is a
similar process for reducing Cu build up in lead free pots.
(I don't know of one)

Regards 

Mike Fenner 
Indium Corporation 

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Pb-free: www.Pb-Free.com 



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Thursday, August 31, 2006 1:49 PM
To: [log in to unmask]
Subject: Re: [TN] SAC305 COPPER RATE REDUCING

Hi Yusuf,
Unfortunately, it is not quite clear what you are asking. You speak of an "
excessive copper rate in both Sn/Pb and SAC305." Do you mean copper rate of
dissolution? Or copper content?
What do you mean be "We could smear excess copper on molten solder?" Do you
mean dross in wave soldering?

Werner
Dear Technetter
As you know that excessive copper rate in both Sn/Pb and SAC305 may 
cause soldering problem on assembly side. For eutectic Sn/Pb solder for 
ex 63/37 copper rate should  not be more than 0.25 %. We could smear 
excess copper on molten solder. We heat up the solder up to 240-250 C 
and then strat to cool it down to 183 C which is the temperature of 
copper melting point, other alloys settle down and copper gathers on the 
surface and we smear it. This is one of the reducinmg copper rate for 
63/37 Sn/Pb solder.
During the HAL process when soldering process is continuing copper rate 
increase gradually so we need to decrease copper rate. In this view, we 
want to learn that if there is any method to reduce the excessive copper 
in SAC305, do you have any experinece aor have you heard of any method 
to reduce copper inside SAC305

Best Regards

-- 
Yusuf GÖMEÇ
Process Engineer


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