Analog Layout Guidelines <was Re: PC boards, Requirements, and autorouters, oh my!>

Mark Amundson 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
>                         preferred...

> 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
spacing
			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.

Mark Amundson,



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