Removing Silkscreens from IC's 1

[mgopalan]

Was wondering if anyone knew a good solvent to remove the silkscreen on top of IC's. I have a product with 7 small PC boards but need to remove the Identifiers from certain IC's (SOIC, TQFP and a couple of LCC's) to deter certain types of individuals....

Obviously, would be nice if the solvent didnt dissolve away the IC , soldermask and the board.

MG

 

[buzzp]

I have used alcohol and lotsa elbow grease in the past but definately not a good way to do it for production.

 

[OperaHouse]

I'd brush on epoxy.

 

[MacGyverS2000]

An electric eraser using the ink eraser refills. 2-3 seconds and it's gone.

 

[btrueblood]

Have you tried acetone or MEK (aka nail polish remover).

 

[ScottyUK]

Dichloromethane will almost certainly shift it. Nasty stuff - be careful.

Careful use of a Dremel drill with a polishing disk works too.



----------------------------------

If we learn from our mistakes,
I'm getting a great education!

 

[VEBill]

Have you thought about reprinting the chips with different (misleading) information ? ;-)

 

[nbucska]

A star for VE1 !
I remember reading that a company copied the PC board of
an all digital instrument, ordered parts for a few thousand
and built and started to test them hoping that a large percentage will function -- but none of them worked...

A few weeks of investigation disclosed that an IC marked as
a standard TTL counter was a custom IC. This was the end of the project -- and of the company...

<nbucska@pcperipherals DOT com> subj: eng-tips

 

[VEBill]

Years ago I had put together a hand-built circuit of moderate complexity. The board included several ICs that were marked with black characters on a silver background. At some point I had to clean the board with 'flux remover' and I gave it a good soaking. When I turned it over all the silver chips had been magically converted to the more-usual black appearance with white letters; and their manufacturer had changed from one company to another.

Years later I tried to reproduce the experiment with a different batch of 'silver' ICs, but the silver paint had been improved.

 

[IRstuff]

That's not necessarily unusual. At Fairchild, we had some p-channel parts that were completely sub'd out except for the final marking and test. I think the parts came unmarked and we put our logo and part numbers on them.

TTFN

 

[OperaHouse]

We used some dip headers for some custom resistor networks. I found the plastic covers fit snugly over standard IC packages. I used these to hide our secret assembly - two dip bridge rectifiers installed on a 14 pin pattern. Just glued it on top of the finished circuit board. Frankly, these efforts just fool the dumbest people.

 

[felixc]

Been successfully using a dremel with the steel wire brush. I know, I know... but it works!
I saw competitors doing the same thing.

 

[MacGyverS2000]

felix,

My only concern with using a steel brush would be bits of wire breaking off and shorting a circuit. I use the Dremel, but opt for a sanding disc, or even the electric erasor I mentioned above.