kicad-developers team mailing list archive

[Seth Hillbrand <seth@xxxxxxxxxxxxx>]

Hi Andy-

In the footprint you mention, note that there are many paste-only pads (see
attached image).  To follow Silicon Labs' recommendation, simply create
your exposed pad with no paste layer and add multiple paste-only pads in
the geometry you desire.

Note that there is a tutorial on the user forum (
https://forum.kicad.info/t/tutorial-how-to-make-a-footprint-from-scratch/11092/1)
that covers this.

-S

Am Mo., 9. Juli 2018 um 10:00 Uhr schrieb Andy Peters <devel@xxxxxxxxx>:

> I followed the discussion about “new non-copper pad paste and mask
> clearances,” hoping that it would suggest how to do something. Maybe I’m
> missing it.
>
> I’m using a part in a QFN-44 package with the exposed pad. The library
> guys have created this footprint in
> https://kicad.github.io/footprints/Package_DFN_QFN and it’s
> the QFN-44-1EP_7x7mm_P0.5mm_EP5.2x5.2mm guy.
>
> The recommendation from the chip vendor (Silicon Labs, but I’m sure it’s a
> standard recommendation) is for solder paste stencil to have a “3x3 array
> of 1.25 mm square openings on 1.80 mm pitch for the center ground pad.” The
> library footprint doesn’t have this stencil stuff, it’s just one big open
> area for solder paste. And I built a board with this footprint and now know
> why the recommendation is for the smaller openings in the stencil.
>
> I figured this would be a good use of the “Custom Shape Primitives”
> feature in the footprint editor. But I can’t figure out how I’m supposed to
> enter anything into this dialog. The buttons are all grayed out. See:
>
>
>
> This is with yesterday’s “testing” build.
>
> Am I missing something? Is this feature not yet implemented?
>
> Application: kicad
> Version: (5.0.0-rc3-dev-5-gfd7f3b8), release build
> Libraries:
>     wxWidgets 3.0.4
>     libcurl/7.54.0 LibreSSL/2.0.20 zlib/1.2.11 nghttp2/1.24.0
> Platform: Mac OS X (Darwin 17.6.0 x86_64), 64 bit, Little endian, wxMac
> Build Info:
>     wxWidgets: 3.0.4 (UTF-8,STL containers,compatible with 2.8)
>     Boost: 1.61.0
>     OpenCASCADE Community Edition: 6.8.0
>     Curl: 7.43.0
>     Compiler: Clang 7.3.0 with C++ ABI 1002
>
> Build settings:
>     USE_WX_GRAPHICS_CONTEXT=ON
>     USE_WX_OVERLAY=ON
>     KICAD_SCRIPTING=ON
>     KICAD_SCRIPTING_MODULES=ON
>     KICAD_SCRIPTING_WXPYTHON=ON
>     KICAD_SCRIPTING_ACTION_MENU=OFF
>     BUILD_GITHUB_PLUGIN=ON
>     KICAD_USE_OCE=ON
>     KICAD_USE_OCC=OFF
>     KICAD_SPICE=ON
>
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Attachment: Screenshot_2018-07-09_10-21-15.png
Description: PNG image

Attachment: Kicad-Pad-Properties.png
Description: PNG image