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Re: PCB Layer Stackup UI


Dick Hollenbeck wrote:
>> ** the first copper layer is number 0 but has a special name 'front', in 
>> addition to any name the user gives it.
> Clarification: each copper layer has both a user given name, and a 
> layer number, just as now. The reserved token 'front' and 'back' are 
> simply "special layer numbers", not actually in the same name space as 
> layer names.
> After declaring the layers up front in the file, throughout the board we 
> will use layer numbers rather than layer names. However, rather than 
> becoming too dependent on the layer count, which changes the numeric 
> value of the back of the board, we will use 'back' in certain situations 
> in place of the layer number for back. Likewise for front, it is a 
> layer number, not a layer name per se.
> We saw an example of this a few postings ago:
> (layers front back) # a LAYERSET object which includes only the front 
> and back copper layers.
> (layers front 1 back ) # I suppose this has to be legal also


I'm assuming from the previous discussion about single layer boards that:

( layers front ) # Front layer only.
( layers back ) # Back layer only.

are also legal. But what about:

( layers front 1 2 ) # No back layer.
( layers 1 2 back ) # No front layer.

I don't know if this makes sense or even if any pcb manufacturers would
make boards with these types of layer stacks. Just curious.


> Techical layers:
> In the case of technical layers, I would be inclined to not expose nor 
> support any "user defined technical layer names". This is as now. But 
> in the board file, I would chose to use a fixed special token to these 
> special layers similar to 'front' and 'back'.
> examples: soldp_fr, soldp_bk, silks_fr, silks_bk.
> These special tokens are treated like layer numbers.
> This way the board never becomes dependent on layer numbers other than 
> copper layer numbers.
> Scream now if this hurts, nod if it seems reasonable.
> Dick


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