Re: For those who believe in electricity

On Wed, 9 Apr 2025 07:39:30 -0500, AMuzi <am@yellowjersey.org> wrote:

A customer produces an industrial machine based on his
father's design patent for which my customer (an academic
electrical engineer PhD) makes up the controller boards. He
scuffs the top of some chips and coats them with epoxy.
>
I can see where a manufacturer would request electronic bits
with no number if it would otherwise reveal information to
competitors but I don't think that's likely for  a bicycle
lamp.  Not unreasonable for a $50K machine.

I've had to repair products that have had the marking removed from the
IC's by the manufacturer.  The laser engraved markings are very
shallow and difficult to read at some viewing angles.  Filling the
holes with paint solves that problem:
<https://www.reddit.com/r/electronics/comments/190764u/make_laser_etched_markings_easily_visible_with/>
However, the shallow laser "pits" can easily be mutilated with a hand
grinder (Dremel tool).  If you have trouble viewing or photographing
IC markings, try different viewing angles.

Long ago, when I was helping design marine radios, we were removing
the markings from certain IC's that we considered proprietary
information.  One day, we experienced a very high failure rate of
these IC's.  It was soon determined that the grinder tool bearing (or
bushing) had become worn causing the abrasive bit to wobble.  That
produced excessive vibration which broke the wire bonds inside the IC.
Fixed with a new hand grinder and a better lubrication schedule.
Incidentally, we eventually discontinued the grinding process after it
was declared a waste of effort because the IC could be identified with
an x-ray photograph of the die.



--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558