Hi John! Well, I have a response that probably isn't what you are looking 
for - " it depends" (cha-ching, Doug gets another Mt. Dew). There are two 
basic camps out in the industry: Camp A: don't use a lead-free BGA in a 
tin/lead solder process because you just don't know what the resulting 
solder joint may be; (2) Camp B: increase the reflow temperature so that 
the lead-free BGA in a tin/lead solder process can reach a uniform 
distribution of Pb throughout the solder joint. Some of the published 
reports also indicate that the BGA construction specifics (i.e. material 
type, die size, I/O, ball metallurgy, e.g.) can play a significant role in 
whether the solder joint integrity would be compromised.  The 
2006/2007/2008 SMTAI Conference proceedings are good sources of published 
papers on the topic. Good Luck.

Dave Hillman
Rockwell Collins
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John Foster <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
10/21/2008 10:21 AM
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[TN] Lead Free BGA'S






Our assembly house recently assembled some boards with Lead Free BGA's for 
us
and when I asked them if they used a lead free process they responded 
with.

We use leaded solder (Sn63Pb37) with a hybrid oven profile to accommodate 
the lead-free BGA. I hope this answers your question. Please let me know 
if you have any more questions."
Is this a common process, is this a reliable process

Any input is appreciated

Thank You
John Foster


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