Unfortunately that beast had: 1) Thru-board vias at the minimum diameter hole size the fab shop would tolerate 2) Blinds, buried... lot's of 'em 3) Multiple independent power planes - boatloads of coupling and bypass caps 4) matched length lines - most being differential pairs 5) Controlled impedance lines 6) BMF Surface mount devices on both sides 7) AND the board was 24 inch by 18 inch
a freaking beast - I was one of the Electrical Designers - I would not even compare notes with the PWB designers - they were true masters of their art. And the commercial package that was used, (Brand A) well - it was pushed mighty hard. The board did, however, work - with a data bandwidth of 144 GBits - no lie. I'm now a lowly laid-off electronics designer trying to peddle a buncha services - and I gotta tell ya both schem and pwb are a major help! (Now, if I can just get a paying customer...) T. On Fri, 2009-11-27 at 20:25 +0100, Gabriel Paubert wrote: > On Fri, Nov 27, 2009 at 12:41:45PM -0500, Tony Radice wrote: > > The idea of a 56 layer board makes my eyes water. > > I Have worked on a 36, and that was (believe me) BAD ENOUGH!! > > > I've never seen more than 24 myself, and designed with more than 6, > but I suspect that your 36 layer PCB had blind and buried vias. > > As long as you don't have blind and buried vias in PCB, I'm not > sure that such a large number of layers is really useful in practice: > vias that occupy all layers really complicate things like BGA > exit patterns (on the inner rings). > > Gabriel _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user