"Dave Sage" <
davesage12@...> writes:
> Making four layer boards sounds interesting but what do you do bout
> the plated through holes. I find even soldering double sided boards
> with no plated holes a bit of a pain.
It's a pain, but this is what I do...
Your stackup is: 32 mil DS clad for power/ground plane "core". 8 mil
SS clad for the two outer signal layers.
Inner layers are for power and ground ONLY. Wherever you have a
through-via, no problem, solder as usual. For power/gnd vias, you do
one of two things:
∗ To connect to the OTHER side's plane, just drill out the whole pad
on the far side (you aren't using it anyway), exposing the inner
plane, solder as usual.
∗ To connect to the SAME side plane, you do NOT drill (or even etch a
hole) on the plane, just leave it solid. Put an oversized pad on
the outer layer and drill it big enough to get a fine-point
soldering iron in there, and solder a wire from the outer layer to
the plane.
∗ When both outer sides connect, you do the oversized copper and hole
on the plane's side, then re-drill a smaller hole through the board
(off-center helps). When you solder the wire through, you should be
able to get the tip inside the hole to get the inner layer.
Yes, this means you drill a bunch of holes in the outer clad before
adhering the layers together. I put the sticky tape on the outer
layers before drilling them, so that I drill through the tape also,
then peel the second layer off and stick it to the core.
Obviously, I avoid four-layer boards when I can :-)