Is that Lean training, where devil is in the details?
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, November 14, 2007 12:55 PM
To: [log in to unmask]
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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