kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxx>]

Just to be clear, the library developers are asking for the ability to 
ignore clearance and ratio settings when creating solder mask and solder 
paste only pads.  If this is the case, it will require a board file 
format change to add a flag to ignore the global and footprint level 
settings.  I would be opposed to changing the code to just assume that 
if it's a solder mask or solder paste only pad that no tolerance or 
ratio is applied.  This would break an existing pads defined this way 
and silently change existing boards.  Given that we are deep into 
feature freeze, the least painful solution would be to set the tolerance 
to 1nm and the ratio (as JP suggested) to 0.00001% for the footprints 
that need to maintain the dimensions of solder mask and solder paste 
only boards.  The change to the overall pad dimensions using this method 
would be far below any board manufacturer's tolerance capabilities.  Is 
this not an acceptable solution?

Cheers,

Wayne

On 04/28/2018 08:44 AM, Eeli Kaikkonen wrote:
> 2018-04-28 15:04 GMT+03:00 Rene Pöschl <poeschlr@xxxxxxxxx 
> <mailto:poeschlr@xxxxxxxxx>>:
>
>     The global settings here are less for ensuring correct alignment and
>     more for a global paste reduction.
>
>
> That's right, that's what I meant. In the example datasheet you have 
> 0.05mm tolerance for the location of the mask in relation to the copper 
> because. But making the mask openings larger or smaller by 0.05mm would 
> be against the recommendation.
>
> It just doesn't make sense to apply global paste and solder mask 
> clearance values to "pads" which don't have copper. The whole reason why 
> non-copper pads can exist is that you need control over the size, shape 
> and location of paste or mask, right? Changing the behavior could lead 
> to problems but luckily the current behavior can be circumvented by 
> adding to clearance fields a very small value which is negligible in 
> practice.
>
> Eeli Kaikkonen
>
>
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