11 Sep
2012
11 Sep
'12
1:31 p.m.
On Sep 11, 2012, at 3:29 PM, Chris Tofu wrote:
are you supposed to be able to tell just by looking at
them if they have multiple layers? Assuming you have one w/multiple layers, and I guess I
already know the answer, it's a huge headache to try and draw up schematics (or
duplicate the artwork rather) w/only photographs of the top and bottom of the board?
You'd need knowledge of the ic's, which isn't that huge a deal perhaps, being
I'm questioning this w/regard to very standard ic's and glue.
It is nearly impossible with photos of just the top and bottom of
the board. It's hard enough with X-rays. Visual inspection of the
board (if you're lucky and they're not buried under planes, you can
see the shadows of the buried traces) and buzzing out with a meter
(assuming the normal caveats and pitfalls of buzzing out) are going
to be a better bet.
Of course, I'm assuming by "multiple" you mean "more than 2"
rather
than "more than 1". 2-layer boards are generally doable with just
photos if there aren't gobs of lines running beneath ICs (and
especially tightly-packed ICs). You'd still want the board to do
continuity checks because you will invariably have lines running
beneath ICs which you will need to sanity-check; the most pesky
of those are the ones which actually terminate at a pin on the
IC under which they run.
I want my APC back. I need to create copies of the
cpu and disk controller cards. I don't have ready access to these. Each of these
boards is nearly the size of a IBM 5150 mobo, so would it make sense that they are
anything but single layer boards? And the APC had 2 video boards, each w/it's own
pd7220.
I'm assuming something like that is at least a 2-layer board, but
anything is fair game. If it's a 4-layer board, I would expect a
significant portion of the inner layers to be power and ground
planes.
- Dave