# Protection against copying of a circuit design

F

#### [email protected]

Jan 1, 1970
0
Hi

It might seem a bit dumb, what are the ways to protect a circuit from
being copied by others?
In both low quantity and industrial scale.

Cheers
Faramarz

D

#### D from BC

Jan 1, 1970
0
Hi

It might seem a bit dumb, what are the ways to protect a circuit from
being copied by others?
In both low quantity and industrial scale.

Cheers
Faramarz

Currently I'm using a Dremel tool to remove part numbers.

D from BC

M

Jan 1, 1970
0
A

#### AndyS

Jan 1, 1970
0
Hi

It might seem a bit dumb, what are the ways to protect a circuit from
being copied by others?
In both low quantity and industrial scale.

Cheers
Faramarz

Practically impossible to prevent copying a circuit design UNLESS
you are able to prove that nothing like it has ever existed in the
public domain.

For many years, I was on the "patent review committee" for one of
the planet's largest electronics corporations, and we got dozens of
patent applications every week for some new "thingy or other". Well
over 90% were simply "inventions" submitted by engineers, in good
published, or patented in some publication that they weren't aware of.
In such a case, we wouldn't spend the time or money for the company
trying to get a patent that couldn't be defended....

That isn't a bad reflection on the brilliance of the engineer....
only an
acknowledgement that there are a LOT of brilliant engineers out there,
and
somebody else did it first, and published it...

Being said, if you really really really think you have done
something that
hasn't been done before, search the patent archives, and do a "google"
on
the subject, and earnestly try to find out if somebody has had the
same
idea and if anything exists in the "public domain" ( i.e. written down
ANYWHERE
where it can be found) before you go to any more trouble.

Andy in Eureka, Texas W4OAH

J

#### Jim Thompson

Jan 1, 1970
0
Currently I'm using a Dremel tool to remove part numbers.

D from BC

I've personally used an electric eraser with ink-type insert.

...Jim Thompson

R

#### RST Engineering $$jw$$

Jan 1, 1970
0
You can use black soldermask on your boards. If they attempt to dissolve it
off, whatever they use on the enamel soldermask will generally eat the epoxy
IC package, resistor color codes, capacitor markings, etc. as well.

If your circuit can stand the leakage, there are a few opaque encapsulants
(mostly in the aircraft industry) that will rip the board apart rather than
let you see inside. Go to the FAA's website and look up Advisory Circular
65-9. There are half a dozen different compounds listed under "sealant".

Jim

F

#### Fred Bartoli

Jan 1, 1970
0
D from BC a écrit :
Currently I'm using a Dremel tool to remove part numbers.

I've seen that done (one customer).
He was so paranoid about copying that he erased the part numbers *in depth*.
Then absolutely nobody one could reverse the board, whatever the effort:
on some parts the chips internal bonding has been erased in the process too.

M

#### MooseFET

Jan 1, 1970
0
Currently I'm using a Dremel tool to remove part numbers.

That only adds a few seconds of delay.

M

#### MooseFET

Jan 1, 1970
0
Practically impossible to prevent copying a circuit design UNLESS
you are able to prove that nothing like it has ever existed in the
public domain.

That is not really true. You can patent the use of a circuit in some
strange new way. Every one knows that the LM78XX regulators will
oscillate. If you used this fact to clock your micro, you could
patent that. You can also get a design patent on parts that the user
sees.

S

#### Spehro Pefhany

Jan 1, 1970
0
Hi

It might seem a bit dumb, what are the ways to protect a circuit from
being copied by others?
In both low quantity and industrial scale.

Cheers
Faramarz

Selling the product at a competitive price and providing good service
are one good way-- it reduces the incentive.

You can try removing part numbers and so on, but it won't slow down
anyone competent by much. If there is locked firmware that is
non-trivial, that might slow some opponents down a bit, although there
are ways to break most protection schemes given a bit of money.
Putting easter eggs in the firmware can help detect that. Don't spend
too much time on any of this, IMHO.

Best regards,
Spehro Pefhany

S

#### Spehro Pefhany

Jan 1, 1970
0
That is not really true. You can patent the use of a circuit in some
strange new way. Every one knows that the LM78XX regulators will
oscillate.

Can *you* make one oscillate without using an inductor or stupidly
long wires?
If you used this fact to clock your micro, you could
patent that. You can also get a design patent on parts that the user
sees.

Best regards,
Spehro Pefhany

R

#### Rich Grise

Jan 1, 1970
0
It might seem a bit dumb, what are the ways to protect a circuit from
being copied by others?
In both low quantity and industrial scale.

Make them so quickly that you saturate the market before anybody gets
around to copying them, and so cheap that it's not worth it for them to
do so.

Good Luck!
Rich

M

#### MooseFET

Jan 1, 1970
0
Can *you* make one oscillate without using an inductor or stupidly
long wires?

Yes, I can use cleverly long wires. If the goal is oscillation, a

M

#### MooseFET

Jan 1, 1970
0
You can use black soldermask on your boards. If they attempt to dissolve it
off, whatever they use on the enamel soldermask will generally eat the epoxy
IC package, resistor color codes, capacitor markings, etc. as well.

If your circuit can stand the leakage, there are a few opaque encapsulants
(mostly in the aircraft industry) that will rip the board apart rather than
let you see inside. Go to the FAA's website and look up Advisory Circular
65-9. There are half a dozen different compounds listed under "sealant".

Just use left hand screws to hold the cover on.

I have had dealings with a company that coated their PCBs with the
black stuff to prevent people from figuring out their design. The
coating seriously degraded performance. I suspect they used the wrong
stuff.

You can also move a trace layer inside the PCB and have the ground
layer on the outside.

S

#### Spehro Pefhany

Jan 1, 1970
0
[....]
Practically impossible to prevent copying a circuit design UNLESS
you are able to prove that nothing like it has ever existed in the
public domain.
That is not really true. You can patent the use of a circuit in some
strange new way. Every one knows that the LM78XX regulators will
oscillate.

Can *you* make one oscillate without using an inductor or stupidly
long wires?

Yes, I can use cleverly long wires. If the goal is oscillation, a

Sound aside, can you demonstrate it with 3' wires?

Best regards,
Spehro Pefhany

M

#### MooseFET

Jan 1, 1970
0
On 28 May 2007 10:36:57 -0700, the renowned MooseFET
[....]
Practically impossible to prevent copying a circuit design UNLESS
you are able to prove that nothing like it has ever existed in the
public domain.
That is not really true. You can patent the use of a circuit in some
strange new way. Every one knows that the LM78XX regulators will
oscillate.
Can *you* make one oscillate without using an inductor or stupidly
long wires?
Yes, I can use cleverly long wires. If the goal is oscillation, a

Sound aside, can you demonstrate it with 3' wires?

I'll have to try it out to make sure but that is likely to be enough.
The LM78XX series has a bandwidth of something like 50MHz. This wide
bandwidth is part of why they have such a low output impedance. 0.02
Ohm output impedance means that it doesn't take much input impedance
to get a gain over unity.

M

#### me

Jan 1, 1970
0
Hi

It might seem a bit dumb, what are the ways to protect a circuit from
being copied by others?
In both low quantity and industrial scale.

Cheers
Faramarz

never produce it and leave no schematic copies in existance...

M

#### mpm

Jan 1, 1970
0
That is not really true.  You can patent the use of a circuit in some
strange new way.  Every one knows that the LM78XX regulators will
oscillate.  If you used this fact to clock your micro, you could
patent that.  You can also get a design patent on parts that the user
sees.

In the US, the invention would need to be "novel", "non-obvious" and
"useful".
I believe the LM78XX example would fail on all three counts.(?)

However, your point is well taken.
I agree with Spehro however. Be first to market, and be the best.

That said, obviously don't make it easy.
Not setting lock bits in a micro is like leaving your keys in the
ignition....
Even though both situations can be compromised by someone determined
enough.

-mpm

K

#### krw

Jan 1, 1970
0
In the US, the invention would need to be "novel", "non-obvious" and
"useful".
I believe the LM78XX example would fail on all three counts.(?)

Not if were a design patent. They're next to useless for such
things, but that's not the issue here.
However, your point is well taken.
I agree with Spehro however. Be first to market, and be the best.

....and keep running.
That said, obviously don't make it easy.
Not setting lock bits in a micro is like leaving your keys in the
ignition....
Even though both situations can be compromised by someone determined
enough.

Just make sure you don't make it harder on your customer (or
yourself) than the perp.

R

#### Robert Baer

Jan 1, 1970
0
Hi

It might seem a bit dumb, what are the ways to protect a circuit from
being copied by others?
In both low quantity and industrial scale.

Cheers
Faramarz
Absolutely; do not make it in the first place!

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