Basically, a via hole only makes connections from one layer of a
board to another.  A Component hole can do the same thing, but
it's primary function is to connect the component to the circuitry.

Via holes are generally smaller in size than component holes.
Normal for everybody can be different but you usually see them
in sizes like .012, .018, .025, .032.  They can be completely
exposed, totally covered (with soldermask), partially covered,
blind or buried.  Blind vias are vias that start on one side of the
board, but stop part way through a multilayer board.  It would
allow you to have traces running through a location where a
through via would be.  A buried via is completely enclosed within
the board and allows you to run track, or mount surface mount
components, to the external layer over the via itself.

Hope this helps somewhat.

Larry Campbell
Supervisor, PWB
BFGoodrich, Avionics Systems

What is the difference between a via hole and a component
hole?  How do you
distinguish these two types of holes in a PCB?

thanks in advance for any information.

regina

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