A contributing factor, but not the root cause.
R. Dean Stadem
Consulting Engineer
Analog Technologies Corp./Lumagine, Inc.
11441 Rupp Drive
Burnsville, MN 55431
(952)894-9228
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Edwards
Sent: Thursday, September 03, 2009 3:15 PM
To: [log in to unmask]
Subject: Re: [TN] BGA Voids
Larry,
Sounds like the reflow profile is too hot on the bottom side...
Paul
Paul Edwards
Surface Art Engineering
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Larry Dzaugis
Sent: Thursday, September 03, 2009 9:54 AM
To: [log in to unmask]
Subject: [TN] BGA Voids
I have a 5-10% void on a bottom side BGA that grows to a 20-40% void
when
the top side is assembled and reflowed.
Paste lead free OM338, profile is peak temp is 246 for 60 seconds.
Immersion tin board finish.
Why would the void expand on a second reflow? There are 22 BGA's on this
assembly. Only a few are growing voids, most voids seen are in the 5-10%
or
less range.
Two parts are in the process of cross sectioning, to verify where the
void
really is. Only have in line x-ray capablility, no angled views.
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