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Date: | Wed, 20 May 2009 20:23:32 -0400 |
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Ingemar,
I am certainly going to follow this discussion!
Having done a lot of RGA testing over the years to validate materials,
processes and leak rates, I am very interested in the direction this thread
may take.
A concern that I might have with respect to greatly diminished leak rates
would be in our ability to accurately and consistently measure them - and
sort out the contribution due to plating adsorption/absorption, etc.
I've been out of the hermetic sealing area for the last 6-7 years so maybe
you have a new wiz bang fine leak detection mechanism. If I recall
correctly, I believe our Veeco leak detectors were a bit
erratic/inconsistent below exp-11 range.
Are you using isotopic leak detection techniques?
Will try to help if I can
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
Sent: Wednesday, May 20, 2009 3:56 PM
To: [log in to unmask]
Subject: [TN] Package requirement Method 1014
Since early 60s it was decided that 5,000 ppmv moisture was maximum allowed
for hermetic packages. Corresponds to a number of monolayers water on the
chip or substrates. Converted to about 1um of leakage hole and molecular
Helium flow it means 5x10exp-8 atm cc per sec. If you seal with maximum 10
ppmv O2 this will give 10 years without getting dewpoint over the dangerous
level. However, with 1 volt chips and line space as little as 0.1 um, and
life expectancy as much as 20 years or more the old limits are questionable
by many. Some recommend a level of exp-11. Then we leave molecular flow and
goes to diffusion . Have anyone of you implemented that ?
Inge
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