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 04 Mar 2010, 2:56 PM
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extra
Joined on 02-04-2010
Posts 10
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Question about error of Pad to pad spacing error
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I have another question about error.
Everything is getting planned, but I have some question about
errors. I just changed options of layer (tools->layer->select from spreadsheet)
then I just changed GND and Power's layer type From plane to routing.
Then I found pic18f8722chip's footprint has over 300 error because of pad to pad spacing error.
So, I just go to option->global spacing, then I changed pad to pad into 4 or less from 8mil.
But error is not disappeared...
Do you know how to solve this problem.
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05 Mar 2010, 6:16 AM
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kevinh
Joined on 31 May 2005
Manchester UK
Posts 885
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Re: Question about error of Pad to pad spacing error
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extra,
why would you change gnd and pwr planes to routing?
if they are not plane layers they won't work.
is your pic surface mount or thro hole? because changing the plane layers changes the pads on those layers.
as for the pad to pad gap, have you checked trac to track? these can get quite tight connected to a fine pitch device.
Best regards
kevinh
See the Orcad User Forum on Google Groups: http://groups.google.com/group/orcad-user-group?hl=en
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05 Mar 2010, 6:53 AM
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Flo
Joined on 28 Jan 2008
Germany, Lower Saxony
Posts 211
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Re: Question about error of Pad to pad spacing error
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You should use the inner layer if you need extra routing layers.
The GND and PWR are just for planes.
Your errors will occure cause of the footprint.
The most footprints have bigger pads for the plane layer.
Regards
Flo
Join the google orcad-user-group.
http://groups.google.com/group/orcad-user-group
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05 Mar 2010, 12:03 PM
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Ron_O
Joined on 09-03-2002
Thorndale, Canada
Posts 1,629
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Re: Question about error of Pad to pad spacing error
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I agree with Kevin and Flo's statements. While it's easy enough to change the plane layers to routing, it's not advisable. Plane layers are unique and use antipads rather than standard pads ie. the pads on plane layers are generally larger than top, bottom or inner layer pads (by default). When you change the plane layer to routing, the antipads become copper pads and are too large, generating the errors you're seeing.
A couple of choices: use INNER1,2 instead as your power/gnd layers (using copper pour to flood) or review all thruhole padstacks and manually adjust the Pwr/Gnd layer pad sizes to be same as top layer. Choice 1 is the most practical but be sure to generate the correct layers in post-process.
Ron O
See the Orcad User Forum on Google Groups:
http://groups.google.com/group/orcad-user-group?hl=en
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OrCAD Community » OrCAD Community Forums » OrCAD Capture to OrCAD Layout » Re: Question about error of Pad to pad spacing error
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