Dear Roy Beckman,

I think I heard about something like this before ... ah, here it is.

_Surface-Mount Technology for PC Boards_ book by James K. Hollomon, Jr.
p. 317
<blockquote>
<p>
... NASA's Jet Propulsion Lab ...
One circuit in particular was fascinating. For a spacecraft, it was a relatively
large card. And, it was fully planar mounted with single-side population. The
back side of the board was bonded to a metallic plate. The circuit was part of
the electronics of the Voyager space probe. ... the metallic backside of the
substrate was used as an outer skin of the spacecraft, as well as a support and
a heat sink for the electronics. Therefore, surface mounting of the components
was a must if they were to achieve a smooth hole-free skin for the spacecraft.
</blockquote>

I wish I knew where to get more details on the Voyager space probe. Maybe Andrew
J Jenkins <[log in to unmask]> could help ?

You also might look into "blind vias".


...
One of our board shops has suggested an alternative strategy to handle
through-hole vias for a PCB mounted on a flat metal plate.  They suggest that we
remove the bottom pads on all non-ground vias and then they will drill the
plated holes out to a depth of 0.010".  (The finished hole sizes for these vias
are 0.012" and 0.018".)  The previous strategy was to drill holes in the
mounting plate at the via locations.

Has anyone had any experience with this scenario?
Can you recommend any board shops that do this?
How reliable are the vias after this drilling?

Thanks for your feedback,
Roy

Roy H. Beckman, C.E.T., C.I.D.
Senior PCB Designer
...

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