Lacking foresight, I went this direction (see attached).
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tom Burek
Sent: Wednesday, November 14, 2007 2:27 PM
To: [log in to unmask]
Subject: Re: [TN] Green Growth between PCB traces
Thanks Steve,
The Foresite link looks a good direction.
Tom Burek, CID+
"Steve Gregory" <[log in to unmask]>
11/14/2007 02:13 PM
To
"TechNet E-Mail Forum" <[log in to unmask]>, "Tom Burek"
<[log in to unmask]>
cc
Subject
RE: [TN] Green Growth between PCB traces
Tom,
I did a search to try and see if I could find something that had to do
with "green dendrites", and I came across this image:
http://tinyurl.com/38lxeb
It's a shortened link from Foresite's ( http://www.residues.com ) photo
library. This is a picture of water soluble flux that was trapped beneath
a part.
Sure is a lot of green stuff there. Looks like the PCB might have been
ENIG too if you notice the vias at the top, they look like ENIG.
Steve Gregory
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tom Burek
Sent: Wednesday, November 14, 2007 2:52 PM
To: [log in to unmask]
Subject: Re: [TN] Green Growth between PCB traces
You may be right, although they look pretty healthy already. I don't
think they need any more "exercise" ;>)
Tom Burek, CID+
"Stadem, Richard D." <[log in to unmask]> Sent by: TechNet
<[log in to unmask]>
11/14/2007 12:54 PM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Stadem, Richard
D." <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Green Growth between PCB traces
They do look pretty bad, perhaps beyond cleaning with known methods. You
may have to consider exorcising them.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, November 14, 2007 1:33 PM
To: [log in to unmask]
Subject: Re: [TN] Green Growth between PCB traces
Hi Everybody!
I have Tom's pictures posted. They're at:
http://stevezeva.homestead.com/files/GreenStuff2.JPG
http://stevezeva.homestead.com/files/GreenStuff3.JPG
http://stevezeva.homestead.com/files/GreenStuff4.JPG
http://stevezeva.homestead.com/files/GreenStuff5.JPG
http://stevezeva.homestead.com/files/GreenStuff6.JPG
Those boards look like they've either been slimed or in Linda Blair's
bedroom while her head was spinning around! YUCK!
Seriously, looks like some sort of dendritic growth to me. I've seen
dendrites before, but not green ones...
Steve Gregory
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tom Burek
Sent: Wednesday, November 14, 2007 11:44 AM
To: [log in to unmask]
Subject: [TN] Green Growth between PCB traces
Hello everyone,
Has anyone ever seen or experienced the phenomenon of this green growth
between the traces and even on some of the pads.
It almost appears as if it is leaching out from under the etchback of the
traces into the space between the traces.
Oddly enough it is only on one side of the board, the bottom side,
opposite the component side.
It will not wash off with DI or Alcohol and a Q-tip, however it will scrub
off with a stiff bristle brush or very gently with an exacto knife.
The soldermask is very thin in spots, (white solder mask).
The PCB is ENIG with white soldermask. FR4 material (IPC-1401/21).
The boards had just gone through HALT testing, (Thermal Shock: 2 hrs. @
85°C then 2 min. 5 sec. swing to -40°C for 2 hrs. This was repeated until
it failed after 136 hrs.) We think this green stuff might have caused the
failure.
With the temperature swings, often there is condensation created so,
possibly created by humidity?
Is there something in the PCB fabrication process that could have lay
dormant until it experienced thermal shock?
I know an analysis of the green stuff is necessary, but I was wondering if
anyone has ever seen of experienced this type of growth before.
Thank you in advance.
I have attached some pictures, but I know somehow they are suppose to get
to Steve to post.
Tom Burek, CID+
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