Re: GPLd PCB Library ( was Re: gEDA-user: Free GNU/Linux hardwaredesign tools)

[Stephen Meier <smeier@AlchemyResearch.com>]

John Dalton wrote:

> > I would happily give you a hand at this but I caution.
> >    
> Thanks.  I'll keep that in mind.  At the moment I have rather
> specific ideas on what I want to do and the job is
> small enough for one person.  If it stalls too long,
> I'll look at using the 'bazaar' development model.
>
>  
> > Each land pattern must match the manufacturing and assembly method. 
> > ...
> >    
> As I understand it, this is all 'built into' the standard.  
>
> Best wishes
> John
>
>
>  
PCB fabrication changes almost daily.  Look at the technology roadmaps 
that pcb fabricators publish. Packaging requirments are getting tighter. 
Trace widths smaller etc etc. Standards are usefull but there is no 
replacement for talking to vendors about what they tjhink actually works 
for their manufacturing process. I think automatically generating 
standard packeges is fine. I think its the non-standard ones that are 
going to be difficult.

I am looking at bga packages in which some traces have to carry more 
current thus disipate more heat then other traces. These pads are made 
over large inorder to disipate the heat away from the solder balls. The 
device vendors may or may not tell you which pads conduct the current. 
Thus a knowlege of the device is needed by the designer.

Steve M.