Now I know why I make so many soft errors. I'm radioactive!
Anyhow, we're doling our best to "eliminate" solder, period.
As an opportunist, I welcomed Mahendra's question.
Flip Chips will be replaced by BBUL and embedded KGD constructions.
That is a better solution than SAC.
________________________________
From: Dennis Fritz <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, March 6, 2012 10:41:55 AM
Subject: Re: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??
Harvey,
Lead is the decomposition product of uranium - over millions/billions of years.
Alpha free lead has been sought for many years for the bumps on IC chips, where
alpha particles could upset semiconductor gates. However, most anything stops
an alpha particle, so Pb in solder joints on a board are usually pretty far away
from the silicon itself. The IBM C4 chip attach technology uses/used 95% lead
material so the IC bumps wouldn't melt during board assembly with 63/37. Pre
1945 lead is prized because it has not picked up radioactive stuff from nuclear
testing (makes you feel good about what we breathe and eat). Anyway, lead
ballast from old ships (back to Roman days) is one of the best sources of alpha
free lead.
SAC solder should not shed alpha particles, and is another reason IBM and others
are looking to take C4 process to Pb-free.
Denny
-----Original Message-----
From: harvey <[log in to unmask]>
To: TechNet <[log in to unmask]>
Sent: Tue, Mar 6, 2012 11:58 am
Subject: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??
Could this be true only of 63-37 or would lead-free SAC alloys also be
potentially guilty of causing soft errors? ----- Forwarded Message ---- From:
"Gandhi, Mahendra S (AS)" <[log in to unmask]> To:
"[log in to unmask]" <[log in to unmask]>;
"[log in to unmask]" <[log in to unmask]>;
"[log in to unmask]" <[log in to unmask]> Sent: Tue, March 6, 2012
8:38:40 AM Subject: Help. Is this true?? Evidently regular solder has
decaying Uranium in it, or somehow generates alpha particles, which are being
blamed for upsets. Some chips are moving to a special “low alpha” solder
internally to avoid this problem on bump-grid-arrays in flipchip parts.
Mahendra Gandhi SME - PWB Technologies Aerospace Engineering One Space Park,
M5/1085A Redondo Beach, Ca. 90278/*[log in to unmask] (Office: 310.813.6857
Fax: 310.812.8630
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