Dan, See the patch that I posted a couple of days ago that implements this for PCB. I ultimately decided to use (abuse) the nopaste flag so that users can specify which pads they want broken up. If this is to be a permanent solution, we should probably add a new flag for this case.
-DC On Sun, 10 Feb 2008 00:37:45 -0500, Dan McMahill <[EMAIL PROTECTED]> wrote: > David Carr wrote: >> I have the distinct (dis)pleasure of making some PCBs with QFN/MLF > packages >> that have exposed copper paddles. I think I'll need to use stencils to >> properly apply paste for these packages. It appears that PCB simply > uses >> SMT pads (slightly shrunk) as the apertures for the paste layer. I > think >> this is a simple effective design for most packages --- except exposed >> ground paddles. These require that the paste be broken into smaller >> "blocks" with say 75% coverage of the paddle. (See Analog AN-772) >> >> Has anyone on the list dealt with this issue in the past? If not, I > wonder >> if there is any way to distinguish paddle pads from regular ones so that > I >> could modify the paste layer code to do the right thing. I guess we > could >> do something like look for square pads with a size > Xmm on a side. > That >> seems a big fragile though. > > That might not be too bad as long as we have a way to specify what X is > and something about how a large pad should be broken up. With the > disclaimer that I'm far from being an expert in the assembly process, it > would seem to me that you'd probably want to break up essentially all > larger pads. > > Does anyone know of particular recommendations from IPC for example > about this? If there aren't any published recommendations, does anyone > have contacts at some board assembly houses who could comment on this > issue? > > -Dan > > > > _______________________________________________ > geda-dev mailing list > [email protected] > http://www.seul.org/cgi-bin/mailman/listinfo/geda-dev _______________________________________________ geda-dev mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-dev
