[sdiy] Eagle analogue & digital groundplanes

[Roman Sowa]

I suppose you didn't make microscopic pictures of assembled board? And 
probably you will not get in troubles by publishing them?

You said "bigger than normal vias". I imagine they were huuge, like 10 
mils pad or so, right? What a waste of space ;)

Can't imagine 500 components on 2.5''sq. People call that alien 
technology, and who has access to real alien technology if not your 
employer...

Roman

W dniu 2015-11-27 o 02:19, Sarah Thompson pisze:
> Yes, that was a spendy board, I think about $1k each as I remember, but
> they had to make the thing small (500+ components on a 2.5" square board
> is challenging). The reason for the 0.003" traces was partly dealing
> with mil spec vias which are bigger than normal, so thinning the traces
> made it easier to get everything in. Impedance wise the board house did
> a really good job -- the TDR tests came out pretty much dead on. The
> board has 8 DC-DC converters on it, so there's a bit of power and
> switching going on, as well as some RAM, a big-ish FPGA, some analog
> stuff, some comms, etc, and it was really too small to easily separate
> all of that. I didn't do too badly, but adding the extra power and
> ground planes made everything a lot more straightforward. Frequencies on
> there are up to about 100MHz digital with a mixture of LVTTL and LVDS,
> maybe 50MHz analog though there's also some DC-100KHz stuff. Something
> for everyone, I suppose... :)
>
> Sarah
>
> On Thu, Nov 26, 2015 at 5:33 AM, Roman Sowa <modular at go2.pl
> <mailto:modular at go2.pl>> wrote:
>
>     3 mils traces? Not every PCB fab can make this. And at that trace
>     width the edges will be relatively ragged quite a bit, so not so
>     much controlled impedance.
>
>     I want a job at NASA too :)
>
>     Roman
>
>     W dniu 2015-11-26 o 12:51, Sarah Thompson pisze:
>