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Securing PCBs from pirates

Discussion in 'Electronic Design' started by REng, Feb 16, 2005.

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  1. REng

    REng Guest

    Hello All

    We have an interesting problem - we are marketing a product (an
    amplifier/signal processor) specific to our applications and we need to
    prevent it from being opened up and reverse-engineered by direct

    I was wondering if anyone here knew of ways to laser off the marking
    from the chips or fix/solder a flat metal sheet (like I have seen on
    some boards) over the components. If the metal sheet is opened up, out
    come the components as well.


    R E
  2. Nick Funk

    Nick Funk Guest

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

  3. Mark Jones

    Mark Jones Guest

    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.

    -- "There's one thing I hate more than politics, and that is religious zealots."
    MCJ 20050124
  4. 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
  5. Epoxy is easy to remove with the right (readily available) chemicals.
  6. Ian Stirling

    Ian Stirling Guest

    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.
  7. Luhan Monat

    Luhan Monat Guest

    Do everything possible in a microcontorller - set the 'code protect'
  8. Guy Macon

    Guy Macon Guest

    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.
  9. Rich Grise

    Rich Grise Guest

    Yes, which also remove the chip packages, which are epoxy, and so the
    numbers. If they want to put the resulting naked chips, hanging by their
    ..003" dia. gold bonding wires, under a scanning electron microscope, they
    have enough money that you'd lose a court battle anyway.

    And if all you want to do is get the numbers off the DIPs, a Dremel is
    probably cheaper than a laser gouger.

    Good Luck!
  10. mike

    mike Guest

    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


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  11. We have an interesting problem - we are marketing a product (an
    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

    Wouter van Ooijen

    -- ------------------------------------
    Webshop for PICs and other electronics
    Teacher electronics and informatics
  12. 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
  13. Barry Lennox

    Barry Lennox Guest

    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

    Barry Lennox
  14. Ken Smith

    Ken Smith Guest

    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

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

    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.
  15. Al Borowski

    Al Borowski Guest

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

  16. Luhan Monat wrote...
    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.
  17. Luhan Monat

    Luhan Monat Guest

    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.
  18. keith

    keith Guest

    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
    ....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.
  19. I read in that Winfield Hill <[email protected]_rowland-
    It applies only in USA only. In other countries, the initial disclosure
    would *prevent anyone* securing a patent.
  20. Luhan Monat

    Luhan Monat Guest

    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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