On Wed, May 25, 2011 at 02:40:58PM -0700, Colin D Bennett wrote: > On Wed, 25 May 2011 23:03:06 +0200 > Gabriel Paubert <paub...@iram.es> wrote: > > > This said, most capacitors look to have a square profile, but > > resonance frequencies observed on microstrip line change between > > mounting the layers parallel or perpendicular to the ground plane. > > The problem is that, for most capacitors, it is very hard to > > determine the orientation of the layers. > > That's interesting. Are you saying that for high-frequency, critical > signals, the orientation of the chip capacitor affects its performance > in the circuit? Is the SMD tape/reel packed in such a way that the > capacitors are optimally oriented, ready for pick-and-place onto a > PCB?
Yes, at least for some high frequency capacitors; look at the following, the last 2 graphs are really amazing: http://dilabs.com/pdfs/Pg%2010-11%20MLC%20Application%20Notes.pdf I have never seen such a large difference myself, but I have seen a measureable difference in some cases. I don't know about capacitors from other manufacturers. When I use capacitors from Dielectric Labs, that's in small quantity, so I get them in bulk in plastic bags and I have to orient them myself. Regards, Gabriel _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
