[PCB_FORUM] Re: mysterious via shifting

Ed:
  Here is something to try:
  delete the bga from the board, 
  set the grid to 31.50 mils
  place the bga
  check the pin spacing of bga
  If the vias come in with the symbol
  check the via spacing now.
  If you manual added pin escapes,
change the grid to 15.75
  then add the pin escapes.
  Now check the via spacing.
   
  Les
  
westfeldt <westfeldt_nbcd@xxxxxxxxx> wrote:
      I'm not sure when Allegro decides it has an unconnect, but if you fanned 
out, copying at 31.5 mils, 5 copies gets you a .02mil error.  I don't really 
see how this is the mechanism for your problem, but you do have a tiny error in 
your 31.5mils spacing, should be 31.496.
   
  Patrick Westfeldt, Jr. 
720-406-0887 
   

    
---------------------------------
  From: icu-pcb-forum-bounce@xxxxxxxxxxxxx 
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Ed Caldwell
Sent: Friday, May 19, 2006 6:11 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] mysterious via shifting


  

Anyone experience a mysterious shifting of vias in Allegro 15.2 s126 
(v15-2-51EU) (12/14/2005) i86... ? 

The design is in mils to 2 decimal places. The vias are in a 0.8 mm BGA (spaced 
at 31.50 mils apart). Somehow the group of vias within the rectangle pictured 
below shifted by 0.10 mils sometime during my edits - cause unknown... 

 

It is important to note that I did not change the database resolution - it has 
remained (mils to two decimal places). The only thing I changed was the routing 
grid which I switched between 25 mils, 5 mils and 0.1 mils as I was working in 
different areas of the layout and I was not working in the area where the vias 
shifted. 

Puzzl_Ed 

Ed Caldwell 
Electronic Design Services, LLC 
Canton, GA - USA

JPEG image

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