Hmmm, This is an area that writting some code could be very usefull. How about a limited auto router that takes the bga io traces out just past the nearest edge?
Steve Meier On Sat, 2007-07-14 at 11:41 -0700, Steve Meier wrote: > Ben, > > I think you have the correct idea. > > I would hand route the traces from under the fpga and perhaps around the > other major periferal chips. Then i would sort out the rats nest by > swapping io pins. After that I would let the autorouter take a shot at > the layout. > > As a explination/warning about the bga image and via in pads. First via > in pad isn't necessary you can have vias off to the side of each pad but > this costs you the use of the top layer. Second, these vias can behave > like chimnies and transport heat up through them wicking the solder back > down. To avoid this the assembly shop/ fab shop coated the back side > with an epoxy ressin. Always always always review your design with both > the fab shop and assembly shop before starting manufacturing. Third, > these boards have to be flat otherwise the bga won't adhear to the pads > or will puddle shorting pads... probably will do both. > > One last note, this was done on a much earlier version of pcb and was > only an 8 layer board. > > Steve Meier > > > > > > _______________________________________________ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user