John,
Ya, I thought of the sand paper thing. I am thinking of using our PWB
cross-sectioning equipment to polish off the applied surface. The
current layer on these ICs has been laser marked. I have been able to
find a component on one of our technicians test PWAs that I am certain
was a factory part. It is marked with ink. So, I am thinking of trying
to polish my way down to the ink layer. The layer I am trying to hit is
about as thin as my chance of success.
These are brokered components, end-of-life kind of thing, buyer beware,
what you see is all you can get...et. al. We have seen isolated
soldering problems and a some dead ICs.
Thanks for the input,
Gary Camac
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: Tuesday, September 09, 2008 12:30 PM
To: [log in to unmask]
Subject: Re: [TN] What's under the blacktop
It depends,
If the device was marked with ink it was almost certainly removed
abrasively
before black top and re-marking.
If the device was laser marked there is some hope as normally these are
double black topped to fill in the impression left by the laser before
re-marking. In this case a VERY fine grade of abrasive paper should
reveal
the original marking.
Did you ask the vendor?? There are many reasons for re-marking most of
them
not bad (and some very bad)
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gary Camac
Sent: Tuesday, September 09, 2008 9:33 AM
To: [log in to unmask]
Subject: [TN] What's under the blacktop
Good morning,
We have some ICs that appear to have been blacktopped. (Steve G. -
thanks for the excellent link in July).
Now the question is why - what is covered up? Our concern is that
commercial grade is being identified as industrial.
Is there a method for looking under the blacktop to determine what was
there before the cover-up?
Thanks,
Gary
Gary Camac
Senior Manufacturing Engineer
DICKEY-john Corp.
5200 Dickey John Road
Auburn, IL 62616-0010
Telephone 217-438-2288
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