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Date: | Tue, 6 Jul 2010 06:47:12 -0500 |
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How does the SJ look like in x-ray?
"X"
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ashok Dhawan
Sent: Monday, July 05, 2010 11:02 AM
To: [log in to unmask]
Subject: [TN] QFN : what is minimum solder thickness to rework
I am debating on what is minimum acceptable solder joint thickness for QFN-32
packages ? Just for clarity , QFN-32 is bottom termination part with no toe
joint due to exposed copper on toe.
We did cross sectioning and found that solder thickness varies form 15 microns
to 45 microns - different footprints. We are wondering what should be minimum
acceptable thickness before we need to rework ? Any graph or relationship to
determine reliability of joint with respect to thickness of joint ?
We are building Class3 products for automotive industry. No information found
on thickness of solder joint Except for IPC-7093 (unreleased draft copy) where
the solder thickness is mentioned as 50 microns.
Anybody to share what should be used as minimum thickness before
reworking ?
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