On  7 Nov 98 at 8:28, Joseph H. Bishop wrote:

> The washers are provided to insulate the screw heads from the top
> of the motherboard circuits to prevent accidental grounding of some
> of the circuits.

  If there is bare metal around the hole, it is intended to make
electrical contact with the head of the screw.  If there is not,
inserting a washer between the screw head and the board will prevent
damage to the board if the screw is over-tightened a little.
  Holes exposing bare metal are typically "plated through", and only
an insert that extended through the hole could hope to provide some
certainty of electrical insulation.  No such insulation is required.

David G

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