kicad-lib-committers team mailing list archive

[Carl Poirier <carl.poirier.2@xxxxxxxxx>]

John, where did you take this screenshot? I am often referring to the
document you linked, but I have never seen such a drawing in it. The
silkscrees for QFN are on page 61-62, but not the one you attached. I do
like it, however. As for the dot, I prefer to ditch it if it's going to be
out of the courtyard, as it could potentially collide with some other
silkscreen.

On Sat, Sep 20, 2014 at 7:10 PM, John Beard <john.j.beard@xxxxxxxxx> wrote:

> On 20/09/14 16:58, Carl Poirier wrote:
>
>> Hi folks,
>>
>> We were unsure how to make the silkscreen for QFN packages. If it's
>> done the same as TQFP, it yields, for the pin one indication, a bar so
>> short it's going to be difficult to see. ...... I'm unsure if there
>> are QFN packages with pins in the reverse order, in which case we
>> can't tell from the silkscreen.
>>
>
> I've previously been pointed to PCB Libraries' document:
> https://communities.mentor.com/mgcx/servlet/JiveServlet/
> download/28883-8838/PCB%20Design%20Optimization%20Starts%20in%20the%20CAD%
> 20Library.pdf
>
> Their method for QFNs is attached. It's an angle over the corners as
> here, but the pin one edge has only one of the lines. The pin without a
> line pointing to it is then pin 1.
>
> The same author also previously used a convention of a chamfered corner
> (i.e. under the component and symmetrical), with a pin-1 dot, outside
> the IPC courtyard in case the pins are numbered in an anti-clockwise
> fashion.
>
> http://blogs.mentor.com/tom-hausherr/blog/2011/04/06/pcb-
> design-perfection-starts-in-the-cad-library-part-15-qfn/
>
> I think the dot is useful, even if the silk outline unambiguously
> identified pin 1.
>
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