On Wed, May 25, 2011 at 7:56 AM, Gabriel Paubert <paub...@iram.es> wrote: > On Wed, May 25, 2011 at 07:11:49AM -0700, Colin D Bennett wrote: >> On Wed, 25 May 2011 06:41:26 -0700 >> Colin D Bennett <co...@gibibit.com> wrote: >> >> > (1) Why is RESC0603L/N/M much smaller than '0603'? >> > (2) Why is there no similarly named set of RESC0805L/N/M for 0805 >> > size? (3) Why does RESC1608M nearly match the '0603' footprint? >> > Is there an imperial/metric naming confusion happening? I thought >> > 0603 was a standard name for this size. >> >> I think I've answered some of this for myself... from Wikipedia's >> “Surface-mount technology” article: >> >> 01005 (0402 metric) : 0.016" × 0.008" (0.4 mm × 0.2 mm) >> 0201 (0603 metric) : 0.024" × 0.012" (0.6 mm × 0.3 mm) >> 0402 (1005 metric) : 0.04" × 0.02" (1.0 mm × 0.5 mm) >> 0603 (1608 metric) : 0.063" × 0.031" (1.6 mm × 0.8 mm) >> 0805 (2013 metric) : 0.08" × 0.05" (2.0 mm × 1.25 mm) >> 1206 (3216 metric) : 0.126" × 0.063" (3.2 mm × 1.6 mm) >> >> So the source of the confusion over footprints is that '0603' is a valid >> name for both a metric and an imperial size.. both different? Whoever >> decided to name the packages that was must have been on crack. > > Indeed. I found a set of recommended footprints that distinguishes > resistors from capacitors: > > http://www.ibselectronics.com/pdf/pa/walsin/smt_notes.pdf > > I have used it quite successfully, including for long edge > capacitors (0612 or 1632 metric) and 4 resistors in a single package > (4x0603 or 4x1608 metric). I also took into account the recommendations > on page 10 when ordering the stencil, shrinking a bit the solder paste > apertures generated by PCB. >
And don't forget Tom Hausher's blog series on the subject "PCB Design Perfection Starts in the CAD Library": http://blogs.mentor.com/tom-hausherr/blog/2010/07/08/metric-vs-imperial-measurement-systems/ _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
