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Padstacks, layernames, process files


Hi Dick,

> In this thread, mostly we are trimming pad descriptions down with
> this, since we do not have padstack support.  

For what it's worth, I just fabbed a kicad board that uses the bitfield
mask to control the inner annular rings for a BGA footprint.  I had to
write a custom script to build my BGA footprints from a textual
description file.  By leaving the annular rings off of selected layers
of the outer pads it made it possible to route out all the traces from
the inner pads. 

I'd hate to see kicad lose it's current ability to fully control all the
annular rings in a padstack independently through the textual
description file. 

I don't mind if all the layers have english names, but it is nice to
succinctly say: "put rings on layers 1,3 4 and 5 only" only", by using a
hex number: 0x0000001D.  Will the proposed changes still have some way
to control all the annular ring layers independently in the
textual description file? 

Some IC layout programs handle the layer names by internally referring
to all layers by integers and having a process text file that gives the
binding between user names and the integers.  The process file also
allows assigning things like layer colors, classes and characteristics. 
The user can either use the integer directly (or a bitmask), or can use
the layer name defined in the process file as a synonym. 

One nice thing that could be put in such a file would be the gerber
extensions for each layer.  My current PCB fab house (4pcb.com) numbers
the layers in opposite order to kicad, and also prefers a different set
of gerber extensions than kicad's default.  I currently run a custom
"tapeout" script on every design to rename all the layers to 4pcb.com's

I really appreciate all the great work that has gone into kicad.  It is
one of the shining stars in the open source world. 

kind regards,
Rick Walker

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