2017-06-17 11:17 GMT+02:00 Luke Kenneth Casson Leighton <l...@lkcl.net>: > On Fri, Jun 16, 2017 at 8:40 PM, mike.v...@gmail.com > <mike.v...@gmail.com> wrote: > >> Bleh. It looked so pretty in my mind. ;-( > > i knoow... btw can you possibly investigate why, when you hit > "reply", the ">"s are not added?
I was using gmail in HTML mode, apparently. I've found a switch. Hopefully this works better. N.B. Was this a problem before the auto HTML conversion on the list? > >> So different layers have different copper thickness. > > in a stack you tell the factory what thicknesses you want, as well as > what material in between, and what thickness of that, too. so you get > different capacitance on different layers. thus, the problem is: you > cannot guarantee the impedance will be identical on different layers. > so having differential pairs on different layers is the worst possible > thing you could do.... *unless* you have access to PCB simulators. > which are ultra-expensive. So it doesn't have to be a problem. As long as you control the layers that have traces have the same thicknesses. _______________________________________________ arm-netbook mailing list arm-netbook@lists.phcomp.co.uk http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook Send large attachments to arm-netb...@files.phcomp.co.uk