On Tue, Nov 16, 2004 at 10:43:02PM -0500, Daniel Nilsson wrote: > On Tue, Nov 16, 2004 at 05:14:01PM +0000, Karel Kulhavy wrote: > > Hello > > > > I suggest that some PCB package creation guidelines were created: > > Karel, > > I'm not sure I completely understand the rules you have outlined > below, maybe you could elaborate a little ? Anyway, here are my comments: > > > 1) The centroid of the package must be really the centroid > > Why do you feel this is important ? This could be quite difficult to > ensure in some cases I think.
How does the automated population process work then? > > 2) The middle of the silkscreen outline outlines the biggest outline that > > can occur. The part has some nominal size and some tolerance. size+tolerance is where the outline should be placed. This ensures when you place 2 parts one next to the other, they will fit on the PCB even in the worst case. > > > 5) It's permitted to have a protrusion in the outline at pin 1, this > > protrusion > > doesn't count for an outline. > > Can you provide an example ? http://images.twibright.com/tns/15dd.html > > > Could you comment on this? Would your guidelines be different? > > In general, I think adding whatever rules of this kind should be done > as library checks in PCB and not only as documentation. Documentation > is obviously needed, but unless there is code that warns about any > violations the end-user can't be sure that guidelines were met. You can't have a code that parses drawings in PDF datasheets and checks the dimensions. Cl<
