I just completed a couple of boards using the 100 pin TQFP and I used 6/6 (0.165/0.165 mm actually) on one board which needed fine pitch to be routable and 10/10 on the other. The fine pitch board had a lot more 0.635 mm pitch parts which the smaller grid was compatible with. It was no real problem routing to the 0.5 mm pitch part though. I use FreePCB which will always align the first trace with the pin and puts the second vertex on grid. Does PCB do that as well, or do you have to switch grids?
The larger board didn't need the fine routing pitch, so I used the fatter 10/10 to lower the cost. But the pin on the TQFP100 was not quite 10 mil wide. So I had to make the initial route a 9 mil wide trace up to the first via. I have not found a way to get FreePCB to route metric trace widths. It may be possible by editing the config file, but I haven't bothered to find out yet. Rick At 01:18 PM 4/25/2008, Ian Chapman wrote: >In my # release: pcb 20080202 version I have:- >DRC[2000 1000 2000 1000 1500 1000] and since they are in square brackets >that works out to be 0.020" spacing and that's fine for through hole but not >so good for TQFP with 0.5mm pad spacing. I'll change the PCB file to 5 or >10 mil if there is not a GUI for that, what clearance do you use? > > > > Hi John, I was using skinny traces for experimenting set to 5 mils width >and > > spacing. Other than that I am using the defaults. I'll have to read on >the > > docs to determine how to change the DRC? > >EMACS ;-) > >I look for the line beginning with "DRC[" >In my ancient version of PCB the numbers are spacing, overlap, minwidth, >minsilk >YMMV > >(* jcl *) > >-- >http://www.luciani.org > > > >_______________________________________________ >geda-user mailing list >[email protected] >http://www.seul.org/cgi-bin/mailman/listinfo/geda-user Arius - A Signal Processing Solutions Company Specializing in DSP and FPGA design URL http://www.arius.com 4 King Ave 301-682-7772 Voice Frederick, MD 21701-3110 301-682-7666 FAX _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
