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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