kicad-lib-committers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Mon, Sep 15, 2014 at 08:41:16AM -0400, Carl Poirier wrote:

> On another note, now that the courtyard is found in the module editor, I
> think it would be fair to add it to the convention. I personally would go
> for a 0.25mm clearance. Anyone objects?

0.25 clearance is the common IPC value for SMD component, measured from
the pad edges and then enlarged to enclose the silkscreen drawings.

Except for LGA/BGA where is bigger to allow for reworking equipment.

The complete table (for the nominal enviroment is):
- Aluminum cap 0.5
- LGA/CGA/BGA 0.5 - 1.0 - 2.0 depending on ball size
- Chip 0.15 (simple R, L, C)
- DFN 0.15
- SODFL, SOTFL 0.15
- Other things 0.25

In short, the exception are flat leads and grid arrays; however if you
don't need an aggressive packing using 0.25 for chips ease *a lot*
reworking. Aluminum caps are big and 'springy' so they have special
arrangements anyway.


-- 
Lorenzo Marcantonio
Logos Srl