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Re: gEDA-user: Centroid data and BGA footprints



Hi Dan,

Google for "IPC 7095"

Maybe some version of it is living at:

http://power611.blog.dianyuan.com/u/61/1200480914.pdf

BTW: I mixed up rows and column indicators ("1A" should have been "A1"
etc.).

Kind regards,

Bert Timmerman. 

-----Oorspronkelijk bericht-----
Van: geda-user-bounces@xxxxxxxxxxxxxx
[mailto:geda-user-bounces@xxxxxxxxxxxxxx] Namens Dan McMahill
Verzonden: zondag 31 augustus 2008 20:44
Aan: gEDA user mailing list
Onderwerp: Re: gEDA-user: Centroid data and BGA footprints

David Kuehling wrote:
> Hi,
> 
> I'm just wondering, how do I get sensible rotation information in the 
> centroid data for footprints that don't have a pin numbered '1', but 
> only a pin numbered '1B'.  In my case that's a BGA footprint, where I 
> chose pin numbers 1B..7E in accordance to the part's data sheet.
> 
> Do I have to rename the pins (and update the symbol), or can I add a 
> kind of rotation hint, or a pseudo-pin #1 to my m4 footprint?

hmm.  Ultimately I think we'll need to modify how pcb stores footprints to
actually keep track of rotation.  Until then we can probably improve whats
currently implemented.

The BGA's I've seen use numbers like 'A1' 'A2' ... 'B1' 'B2' ... where
A1 is the top left and the letters give the row and the numbers give the
column.  Does anyone know of a controlling standard for BGA's and PGA's with
regards to how pins are numbered?  Besides that does anyone have a wide
enough experience with either of these to comment on how they are numbered
in practice?

David, are you saying your top left pin (when viewed from above with 0
degrees rotation) is '1B' and there is no '1A'?

Where I'm going with this is I can look for names like '1A' or 'A1' if there
is no pin numbered 1 but I need a moderately broad view of what can be
expected.

-Dan


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