[PCB_FORUM] Re: mysterious via shifting

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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