Copper and zinc contacts

Discussion in 'General Electronics Chat' started by jaymax, Aug 14, 2010.

  1. jaymax

    Thread Starter New Member

    Aug 14, 2010
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    0
    I am designing a low voltage measuring project which fits into a zinc plated galvanized case. The circuits are to be mounted on a copper ground plane which is grounded to the case. What are, or should be, the considerations here for the contact of the dissimilar metals, corrosion issues, ground currents etc.

    Thanks!
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    You should use nylon or another non-conductive material to isolate the 2 metals from each other. Standard washers/spacers can be used for this application.
     
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Copper and zinc are pretty far apart on the galvanic scale so I'd keep them apart and make your case to board connection with a separate wire(s) soldered to the copper board and connected to to the zinc case with crimp on terminal(s) - preferrably also galvanized with zinc but common tin lead will work as it's somewhat in the middle of the scale between copper and zinc.

    http://en.wikipedia.org/wiki/Galvanic_corrosion

    Then again I've used stainlesss steel hardware in this situation and had no problems.
     
  4. jaymax

    Thread Starter New Member

    Aug 14, 2010
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    0
    So you would make the case of stainless steel and use the copper back plane.

    Thanks!
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
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    No, I would keep the case as cast zinc and just use stainless steel nuts, bolts and washers - that or solder plate the area of the copper board that will come in contact with the hardware you're using. Unless you need a lot of it stainless is the way to go anyway due to better strength and appearance.

    I do love those cast zinc or aluminum cases, especially the ones that have an integral mounting flange. A bit pricey but they're durable, take paint well and serve as nice heat sink area for regulator ICs.
     
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