Vitaliy <spam <at> maksimov.org> writes:
> mind-blowing. I was surprised to learn that multi-layer boards are basically 
> just glued together: to make a 4-layer board, they sandwich a double-sided 
> PCB between two other double-sided PCBs, press them together, and voila!

I did everything from manual board making (single and small series, 1 and 2
sided) through 8-layer buried via board rework/repair (one place I worked at a
long time ago was just downwind of a large multilayer board maker - we knew when
they had a lot of work from the smell and from their guys not showing up for
lunch ...). I tend to be a little blase about technologies because a lot of the
low cost boards are made manually (literally so). Machines can be nice but one
must justify the costs, so cheap labor countries use few machines and vice
versa. I assume that you visited a US/S. California board house (and not one in
the boonies).

In any case, most non-smd large series boards (phenolic, low resolution) are
made in a totally different way from FR4 boards. Holes are punched, not drilled,
boards are punched out, not router cut, copper masking is printed on not
photoexposed, and so on.

Then again high end boards made of ptfe and alumina are done in a different way
again. So there is no easy way to answer the o.p.'s question.

Peter


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