[PCB_FORUM] Re: mysterious via shifting
- From: Les Wong <maveric0@xxxxxxxxxxx>
- To: icu-pcb-forum@xxxxxxxxxxxxx
- Date: Sun, 21 May 2006 11:02:36 -0700 (PDT)
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
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