PCB shops wil always modify the Gerber files to fit their processes to yield the desire impedance. Therefore the stack ups vary slightly from shop to shop.
The specified stack up is in the files supplied. Terardrops are used for added robustness on connector pins that may be stressed during use. Gerald On Tue, Jan 19, 2016 at 7:45 AM, Travis Estep <[email protected]> wrote: > To your first question, I'm not sure about the stackup. Maybe Gerald can > weigh in. > > As for the trace/space tolerances, each manufacturer is different. Some > will not even attempt to print the boards, but some will try with the > understanding that as you get away from their minimum specs, the yield also > goes down. For example, if they specify a minimum trace/space of 4/4, but > you need 3/3, they may print it, but you may see something like 4 of every > 10 boards are unusable. And they won't replace those boards. You took the > chance on your own free will knowing that you weren't within spec. So you > may need to order 40% more boards than you need just to have enough to > fulfill your needs. > > The "wedges" you see are called teardrops. Some people use them when > connecting to vias/pads as a stress relief. It prevents the traces from > breaking away from the pads so easily. They are not essential, but do help > more than you'd think. > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- Gerald [email protected] http://beagleboard.org/ -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
