kicad-lib-committers team mailing list archive

[John Beard <john.j.beard@xxxxxxxxx>]

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.

Attachment: QFN_Silk.png
Description: PNG image