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static sensitive PIC chips?

Discussion in '8bit Microcontrollers' started by A.P., Jan 3, 2004.

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  1. A.P.

    A.P. Guest

    Hi all,

    Has anyone else had problems with 16f628 chips. I am building a small
    project that located in another part of the house from my programmer. Both
    rooms are located in a carpeted basement, after making about 5 trips from
    programmer to target board the chip would not program anymore. I wasn't
    extremely careful in regards to avoiding static discharge other than
    grounding myself before removing the chip and again before programming it.
    After the first chip went defective I was much more careful, transporting
    the new chip in conductive foam. Even with this precaution 2 more chips
    are no longer responding in the programmer. Is it just me or are these
    chips super sensitive?

    Alan
     
  2. There must be more to it or you got several thousand volts of static
    going thru you. Try wearing some antistatic strap, wear different kind
    of shoes, use a humidifier in the house.

    If you mishandle the part you may get issues also. Don't hot plug the IC.
     
  3. What you need t do is wear polyester, maybe cotton. No wool. Use rubber
    soled shoes too. Those leather soled shoes generate thousands of volts, just
    walking around.
    Next take an empty spray bottle. Add some dishwashing detergent to it, and
    fill with water, mix up reasonably well (don't overdo it because of the
    suds).
    Then spray the carpet with the soapy water.
    next follow normal static discharge practices.
    The fact that you didn' feel a static discharge doesn't preclude one
    happening though.
    The soapy water helps a lot to cut down on static discharge, it's not
    perfect though.
     
  4. Dave Garnett

    Dave Garnett Guest

    Static damage is rare and fairly random. I would worry much more about the
    programmer and the algorithms it is using ...

    Dave
     
  5. I'd prefer the use of an anti-static carpet spray, which wouldn't make
    the carpet as sticky as detergent would. Over time the detegerent will
    attract dirt and the carpet will soil faster. The ESD carpet sprays also
    cause some increased soiling, but it's not as bad.

    A carpet in the basement makes me think it's not nylon or wool based,
    and is therefore may not be causing a lot of static. An increasing
    number of "rec room" type carpeting is now made of polyolefin. The
    latest olefin carpets, especially olefin/nylon mix, don't generate
    nearly as much static.

    For my money, the static is being generated while working with the
    programmer, chips, and other circuitry at the desk. Some wood desktops
    (real wood, not photo printed melamine) generate copious amounts of
    static just by rubbing your hand over it. Now with winter (the air is
    drier despite the rain!) these sorts of things become a problem again. I
    like to put a small anti-static mat under my feet in my carpeted office.
    It cost about $50 some 10 years ago, and I never have had static
    problems since. (And out in my garage the floor is concrete and I have a
    50's metal desk. What static?? <g>)

    -- Gordon
    Author: Constructing Robot Bases,
    Robot Builder's Sourcebook, Robot Builder's Bonanza
     
  6. What about your pc, is it grounded? I have really really mishandled my
    pic's ( also 16F628) and never burned one, BUT - i have burned a few
    pc's till i made a new grounded supply for them. If your programmer is
    powered from the pc it can get charged from there. An ungrounded pc
    _will_ get static. And if you discharge yourself and then touch the chip
    in the programmer, you dishcarge the hole lot throug the Pic. A
    defective "0" (dont know the english word - you got "phase" and "0" in
    your home-supply) could make it even worse.
    Niels
     
  7. Bob Harris

    Bob Harris Guest

    Try to do it in the same room. You are damaging the devices with static
    electricity.

    --Bob
     
  8. A.P.

    A.P. Guest

    Thank you all for the great advice, I will try them out.

    Alan
     
  9. Alan Holt

    Alan Holt Guest

    It's just you(r carpet).

    Seriously, if you can't remove the carpet, you should invest in a static mat
    and wrist strap.
    I have carpet in my basement, but I am very careful about grounding myself.
     
  10. Luhan Monat

    Luhan Monat Guest

    Hi,

    I use these (and many other chips) all the time. I have seldom had one
    fail. Here are my 2 rules...

    1) Never plug or unplug the chip with the circuit powered.

    2) Keep youself grounded to the circuit with one hand while inserting or
    removing the chip with the other hand.

    Not only with this prevent damage from static charges but also for 120
    volt 'leakthru' that many devices have even when powered off.
     
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