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Epoxying over chip numbers?

Discussion in 'General Electronics' started by John Muchow, Jul 2, 2004.

  1. John Muchow

    John Muchow Guest

    We have several prototypes being built over the next few weeks and
    wanted to hide the chip numbers of some of the glue logic. We've
    sanded them off up to now, but that's an awful and time consuming way
    to do it. A search of the sci.electronics groups came up
    empty....amazingly.

    Does anyone have any recommendations for covering up the numbers on
    plastic and ceramic DIP packages? Loctite's black Prism 410 adhesive
    looks good, but we're not sure if it will stick well enough or if it
    can be pried off like a "pancake".

    Or is sanding still the best option for doing this?

    Thanks!

    John Muchow
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  2. Jim Thompson

    Jim Thompson Guest

    Electric eraser with "ink" type insert... very quick.

    ...Jim Thompson
     
  3. Dennis Clark

    Dennis Clark Guest

    You're wasting your time. Anyone that would be interested in figuring
    it out will anyway, and those that aren't won't anyway.

    IMO,
    DLC

    : We have several prototypes being built over the next few weeks and
    : wanted to hide the chip numbers of some of the glue logic. We've
    : sanded them off up to now, but that's an awful and time consuming way
    : to do it. A search of the sci.electronics groups came up
    : empty....amazingly.

    : Does anyone have any recommendations for covering up the numbers on
    : plastic and ceramic DIP packages? Loctite's black Prism 410 adhesive
    : looks good, but we're not sure if it will stick well enough or if it
    : can be pried off like a "pancake".

    : Or is sanding still the best option for doing this?

    : Thanks!

    : John Muchow
    : -- remove SPAMMENOT for e-mail responses --
     
  4. Zak

    Zak Guest

    Unless the device is trivial and the buyers have trivial skills.

    Or if the device is 'magic' - golden ear audio comes to mind. Audio
    reviewers do not have great technical skills usually. Hmm... reminds me
    of a product that had the 'advantage' of no resistors in the signal
    path... great invention.


    Thomas
     
  5. Mark (UK)

    Mark (UK) Guest

    Hi!

    Don't bother for standard LS/4xxx logic - anyone interested would
    desolder it and chuck it in a digital chip tester, and it will come back
    what the chip number is.

    If you've got some flip flops in there, put a chip or two of those into
    a GAL and secure it - that will stop all but the most hardened design
    theives. Even better, put as much of the logic as possible into a CPLD,
    again securing it.

    Yours, Mark.
     
  6. CWatters

    CWatters Guest

    How are you doing the sanding? Try using different tools in a dremel.
     
  7. Impmon

    Impmon Guest

    Epoxy can be removed one way or another. I've seen some chips whose
    number was hidden under black marks (permanet marker) but it can be
    cleaned off with some effort. Sanding is still a foolproof option.

    If you have dremmel, try using that. It can sand off number in a
    pinch but don't overdo or the chip might get too hot or worse, you
    might sand the case clean off and expose the chip.
     
  8. Al

    Al Guest

    Does that work on laser scribed devices also?

    Al
     
  9. Jim Thompson

    Jim Thompson Guest

    I haven't done it in years... I was last "hands-on-discrete" in 1987,
    but I'd think so, the "ink" type insert is actually abrasive.

    ...Jim Thompson
     
  10. Dave Platt

    Dave Platt Guest

    You're wasting your time. Anyone that would be interested in figuring
    For an interesting "golden ear" story relevant to this issue, see:

    http://groups.google.com/groups?selm=
     
  11. Don Bruder

    Don Bruder Guest

    For my nickel:
    Any manufacturer who grinds chips (and therefore makes it impossible for
    me to service the device, whatever it might be, but replacing chips that
    die (they do that eventually, yknow) is a manufacturer who will never
    again receive any money from me.
     
  12. Jamie

    Jamie Guest

    acetone
     
  13. Robert Baer

    Robert Baer Guest

    Abrasion does the trick: sanding, milling, laser.
    However, anyone can still find out what chips you used, so why bother?
    No other company i know of does something as infantile as hiding part
    numbers.
     
  14. Robert Baer

    Robert Baer Guest

    *EXACTLY* !!
     
  15. Robert Baer

    Robert Baer Guest

    Nope; hasn't worked since the mid 1980s...
     
  16. John Muchow

    John Muchow Guest

    Electric eraser with "ink" type insert... very quick.

    That's a great idea!
    Too much like using a Dremel (with the rubberized wheel) though...what
    we're doing now. I was hoping to just put a drop of epoxy on the chip
    and go. After thinking about it, I'm pretty sure it won't stick well
    enough to the ceramic packages. But, it would be nice if it could
    work with PDIPs.


    John Muchow
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  17. John Muchow

    John Muchow Guest

    You're wasting your time. Anyone that would be interested in figuring
    You're probably right, but we're just trying to keep things in our
    pocket until the prototype testing is done.


    John Muchow
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  18. John Muchow

    John Muchow Guest

    Don't bother for standard LS/4xxx logic - anyone interested would
    Forgot about those things. ;-)
    Good ideas, thanks!


    John Muchow
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  19. John Muchow

    John Muchow Guest

    How are you doing the sanding? Try using different tools in a dremel.

    We're currently using a Dremel with the rubberized wheels and they
    work great. But, it takes a while to do and it's easy to damage a
    chip. We'd love to place a drop of epoxy on the plastic packages and
    be done with it. :)


    John Muchow
    -- remove SPAMMENOT for e-mail responses --
     
  20. John Muchow

    John Muchow Guest

    For my nickel:
    I'm stunned that you've never, ever purchased a product that uses a
    microprocessor. The manufacturers don't post the source code and
    that's no different IMHO than hiding chip numbers.


    John Muchow
    -- remove SPAMMENOT for e-mail responses --
     
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