kicad-developers team mailing list archive

[Dick Hollenbeck <dick@xxxxxxxxxxx>]

On 04/26/2013 03:02 AM, Dimitris Lampridis wrote:
> On 04/25/2013 02:22 AM, Simon Huwyler wrote:
>> As some PCB manufacturers (i.e. seeedstudio) have different clearance-
>> an width constraints for outer- and inner layer, I had the idea to teach
>> Kicad to manage “layer based” constraints.
>  >
>> Ok, for the moment, I chatted enough. What do you think about it?
> 
> Hi Simon,
> 
> We use Kicad at work and we would like to get involved in the 
> development process, not only as a means to return something to this 
> excellent community, but also to actively improve the tools we are using.
> 
> To this end, I've also just subscribed to this list (hi everyone!), and 
> I'm keeping a list of features/fixes that I would like to start 
> proposing for implementation. I'm responding to your idea because it was 
> already on our list.
> 
> Now, back to your suggestion, here's my two pennies' worth:
> 
> a) in my opinion, this should not be tied to layers. Instead it should 
> be part of a "net class" in the design rules. This would allow the user 
> to keep separate inner/outer constraints per net class. When 
> creating/modifying a net class, the user will be able to specify the 
> applicable layers (eg. [2-4,7,12]). This approach is also cleaner, since 
> all constraints will be in the same dialog window.
> 
> b) why don't you make a "blueprint" in launchpad for this? I'm no expert 
> in how launchpad works, but it looks like the right tool for submitting 
> ideas and technical details.
> 
> Cheers,
> Dimitris


Hi Simon,

I was thinking what Dimitris is thinking, before I read his post.  Clearly you took the
path that allowed you to get it working.  And usually that is the best path.  But in this
case I think we can all see a certain discomfort in blurring what the layer setup dialog
is for.

The first question I have is this:

*) is the benefit of using the smallest clearance and spacing on the outer copper layers
worth the this trouble in general?  Are your boards really that busy on these outer
layers?  Seeqstudio is forcing you down a path that you do not have to take.  You can use
them by using the wider spacing in the inner layers, on all layers.  What are you gaining
really?  Or is it just one part with narrow pad spacing pushing you down this path?


*) next question is, who else needs this?


*) the documentation would need to be updated if we were to go down this path.  Otherwise
we might get bug reports when somebody sees a different spacing on a different layer for
the same net.  Of course this happens on spin 2 of the board, after you have forgotten
about the layer specific override and cannot figure out why that layer is different.


As you can see, I am not taking a stand on need, only trying to see if it exists.


Dick



















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