Analog Layout Guidelines <was Re: PC boards, Requirements, and autorouters, oh my!>
mamundso at MR.Net
Thu Jun 12 03:42:38 CEST 1997
Joe Grisso wrote:
> I use a 30 mil trace at minimum, with a 50 mil trace
> We use a minimum track width of 12 mils,
> and a preferred track width from 18 to 20 mils...
> pad/via size of 40 mils with a 20 mil hole diameter.
> These are ABSOLUTE MINIMUM LIMITS. Wherever possible,
> use thick traces, and be generous with pouring power
> and ground planes.
> Joe Grisso - CAD Designer
> jgrisso at dod.com
Here are some my preferences:
Donut (Pad) Size: 100 mil with exception for DIPS and small cap lead
IC will have unique pin 1 pad shape.
Track size: 30 mil tracks, 50 mils or more for supplies
Spacing: 50 mils or more if possible.
Copper Pours: Use ground and supplies for pours to fatten tracks to
minimize copper removal. Discretion needed on pour to
track spacing. Pour grounds and returns first to
minimize supply noise/bounce and maximize shielding.
Mechanical Prefer 125 mil holes on the corners at 250 mil spacing
for standoff posts. Do not pour copper near holes to
avoid ground loops/magnetic induced eddy currents.
Other: Prefer single sided with minimal jumpers over double
sided. I would rather pin through two double sided
boards than throw money at three or more layers.
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