Securing PCBs from pirates

Epoxy potting or encapsulation with metallic soldered/welded enclosure. This would keep everyone except the really determined inquisitive person out.

Nick

REng wrote:

There is such a thing - it's called potting compound. Probably an epoxy. Once circuit is imbedded, there is almost no way to get into it without destroying it.

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Do everything possible in a microcontorller - set the 'code protect' function.

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Luhan Monat (luhanis 'at' yahoo 'dot' com)
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Sanding the numbers off the chips can deter someone unskilled in the art from directly copying your device...UNSKILLED. Potting the thing will slow them down a little more. But it will also make it impossible to repair or upgrade the unit.

Once had a problem with a military product that had been conformal coated. While the unpotting chemicals were indeed readily available, there were significant OSHA restrictions requiring a major investment in ventillation hoods and worker protection in order to use 'em.

For one skilled in the art, the problem is figuring out WHAT to do, not HOW to do it. Given the external definition, it's often easier to redesign it than to reverse engineer it.

If your design will change the world, get yourself a GOOD patent firm and a BIG pile of money to defend it.

Put what you can inside a microcontroller or an ASIC or some such device. Sand the labels off if you must. Put your effort into sales. It's a lot more important to be first to market with sufficient marketing to generate demand and sufficient supply to meet it. A good idea started on a shoe string will invariably be taken away from you no matter what you do to obfuscate the implementation.

mike

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Complete waste of time. Anyone who wants to figure it out will do. best way is to put some critical functionality in a MCU or PLD

it.

Epoxy is easy to remove with the right (readily available) chemicals.

Parts with their numbers removed are also a fairly reliable indicator that the profit margin is attractive and the device is simple and unprotected enough to be well worth copying (at least in the eyes of the company manufacturing it).

Making it really tiny and incorporating programmable logic or microcontrollers helps. But there are some products that are just not possible for company A to make a buck off, whereas company B can do it anytime they want. Sometimes those products never make it into production, because there is nobody with a real profit motivation.

Best regards, Spehro Pefhany

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It's not easy.

It is possible - ceramic shell (with feedthroughs) with circuit board enclosed in thermite. Inside shell is random arrangement of fine wire, potted, and internally connected to a microprocessor to verify it. Energy storage (capacitor or battery) designed to fire the thermite on disruption of the shell, or temperature limits, or neutron or other penetrating radiation fluxes.

This is still vulnerable to using explosives to blow it apart. To get away from that, you need to go with a meter or so standoff distance, and swap the thermite for high explosives. Any penetrating particle intended to diffuse the components for analysis without giving the mechanism time to set off the scrambler will itself set off the explosives due to its kinetic energy. Special care has to be taken to get the explosives to atomise the circuit and not to leave any usable clues.

If your direct competitors are as good at reverse-engineering as I am (or are willing to hire me) the methods you describe *might* delay the reverse-engineering by a day or two.

The other methods discussed that don't involve a redesign might give you a week or so. I can remove epoxy, X-ray parts, and open ICs and compare the chip to my collection of already-opened chips.

A redesign with a uC or programmable logic raises the bar quite a bit, and might force me to design a plug-in replacement just from looking at the inputs and outputs. Unless it's a reverb or a PRNG; those are quite hard to reverse-engineer from the signals alone.

--
Guy Macon

Right. But you'd have to publish or disclose enough design details to allow reproduction, i.e. schematics and program listings in the manuals, sent to every customer, etc.

The one-year time limit for applying for a patent after a public disclosure would have run out. Perhaps you could attempt to sell your documented design info to a competitor who was being sued for patent infringement... if you knew about it (quite a number of "ifs" in there), but remember, you had previously disclosed this info to all your customers, and made it public. OK, you could be an expert witness, but that's just a little pay by the hour.

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 Thanks,
    - Win

1. Make and sell a few of your devices without patent or any other protection. Document all development and sales.
2. Wait until some large company rips off your design and creates the market for the item.
3. Approach the above company threatening to give aid and assitance to a direct competitor of theirs. Their competetor can get a patent using you as the intial developer. The company that stole your design is barred from ever getting a patent do to your 'prior art.'
4. If the company doesn't give you sufficient compensation, go to their competitor and make a deal with them.

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Luhan Monat (luhanis 'at' yahoo 'dot' com)
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Make it too cheap to be worthwile to reverse engineer. If the difference between manufacturing price and sell price is high enough

*everything* can (and probably will) be reverse-engineered. Lots of engineers regard chips with removed marking as a nice puzzle for the weekends.

Wouter van Ooijen

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Webshop for PICs and other electronics Teacher electronics and informatics

A few suggestions:

If you are making very many, you can get the chips numbered with your own numbering system.

Sanding off numbers delays the other guy by about 3.2 seconds if that is all you do. You also risk creating static in the process.

Placing chips on both sides of the PCB can help to slow down the guy with an X-ray machine. Adding a layer of squiggly traces to the PCB can also help.

Don't let the managers bring some-one through on a tour. It really happened.

Make the circuit on 2 PCBs and attach then together face to face with a bunch of bus wires and then fill the gap between them with epoxy.

Patent everything but a real dark secret, including the screws that hold it together. It is common for those who wish to copy a design to do a patent search.

Desiging the housing such that it is hard to get apart helps about as much as epoxy on the PCB.

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Selling the device, with enough details to show the operation will protect it for *your* use, but it deosn't do anythign to otherwise "protect" the widget.

....and that one-year "bar" is only for US patents. Be careful with that "public disclosure" too. "Disclosure" includes "recieving commercial value". If you've told a potential customer that you have a widget that does "framis", even though you haven't told how it does "framis", the clock has already started.

If it's the same idea the prior art (the opponents "patent") will nullify his. he won't even get the little pay.

--
  Keith

My suggestion was a bit tongue-in-cheek. Just like to inject a different line of thought. I have been envolved in some very testy patent battles. Mostly, its a game of get your product to market hard and fast; setup offshore manufacturing from the getgo; leave your competitors eating your dust.

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Luhan Monat (luhanis 'at' yahoo 'dot' com)
"The future is not what it used to be..."
http://members.cox.net/berniekm

I agree, your disclosure helps protect anyone who seeks to use the idea against someone who manages to later get a patent on the idea.

Yes, I argue that Luhan's concept of later patenting the idea is wrong.

--
 Thanks,
    - Win

I read in sci.electronics.design that Winfield Hill wrote (in ) about 'Securing PCBs from pirates', on Wed, 16 Feb 2005:

It applies only in USA only. In other countries, the initial disclosure would *prevent anyone* securing a patent.

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That will slow them down abit, but could still be beaten if the 'pirate' is very determined.

for instance.

Al

Almost impossible to do in hardware, at least against a determined competitor, But are really sure your product is that unique and valuable, or is it wishful thinking?

Start with ground-off part numbers, a $30 rotary tool will do that. Maybe simple epoxy encapsulation will help, but there's a number of solvents, "Stirranol" is one commercial product that works well.

Do as much as possible in a cheap micro with protected code, build the critical parts with 01005 SMD parts, place a steel shield over it, and then smother it with an epoxy and Kevlar bandage would keep out most folk.

Barry Lennox