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How are PC boards made?

Discussion in 'Electronic Basics' started by Don A. Gilmore, Jun 5, 2006.

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  1. Hi guys:

    How are ordinary copper-clad printed circuit boards made? Is the
    copper deposited onto the substrate by some process, or is it attached
    as a foil with an adhesive?

    Thanks for any replies.

  2. John  Larkin

    John Larkin Guest

    Usually the board house buys copper foil clad laminate and etches the
    unwanted stuff away, then electroplates the bores of the


  3. OK, but how is the original copper foil attached to the board? Is
    there an adhesive involved, or is it deposited in a molten or powder
    state somhow?

  4. John Fields

    John Fields Guest

  5. notbob

    notbob Guest

  6. DJ Delorie

    DJ Delorie Guest

    In a nutshell...

    Copper foil is glued to a "substrate" board (anything from plastic to
    teflon, usually fiberglass). The fab shop drills all the holes in it,
    then plates (usually electrochemically) additional copper over it all
    (making the foil thicker as well as electically connecting through the
    holes). Then, a mask is applied over the copper and whatever isn't
    masked is chemically removed.
  7. John Larkin

    John Larkin Guest

    Or they pretend to. I almost never get 1 oz or 2 oz when I specify it.
    On one of my fab drawings, it says


    which helps.

  8. John Larkin

    John Larkin Guest

    As far as I know, roll copper foil is epoxied to the laminate, which
    is usually epoxy-glass. The foil is usually "black oxide" treated on
    one side to stick better.

    For some exotics, generally microwave stuff, the copper is
    electroplated onto the substrate and not glued. These are usually
    teflon or polyimide boards, low-loss stuff, and they want both good
    adhesion and a micro-inch smooth, pure copper surface on both sides of
    the copper.

  9. PC board material has a solid copper foil glued (or otherwise
    attached) to the fiberglass. When you make your board, any copper
    that doesn't look like your circuit is etched away.

    Peter Bennett, VE7CEI
    peterbb4 (at)
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  10. John Fields

    John Fields Guest

  11. /dev/phaeton

    /dev/phaeton Guest

    And for multilayer boards do they simply epoxy each layer on top of each
    other layer?

  12. Guest

    Multilayer ( 4 or greater) actually have prepreg (a form of glue) as
    the outer layer

    A typical stack might look like:

    Top ------------ 1 oz Cu
    Prepreg ----------
    Inner 1 ----------- 0.5 oz Cu
    Core ----------- [FR4, typically. Depends on application]
    Inner 2 ----------- 0.5 oz Cu
    Prepreg -----------
    Bottom ------------ 1 oz Cu

    [thicknesses and types of core / prepreg are carefully selected for
    impedance controlled boards]


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