Alignment of Component Outlines in Eagle

Questions relating to designing PCBs

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beebo
Posts: 6
Joined: Fri Mar 25, 2011 3:07 pm

Alignment of Component Outlines in Eagle

Post by beebo » Mon Jan 21, 2013 12:54 pm

Hi,

I'm creating a very small, densely populated board...it's that way out of necessity. My intention is to get them assembled by a manufacturer. Gold Phoenix says they need 12mil ("0.3mm") spacing between components for assembly, and at this point every mil counts!

I'm using Eagle with many components from Sparkfun's library. In the PCB layout the tDocu Layer shows the outlines of components, and these outlines appear to be about 8mil wide...so here's my question. Can anyone tell me whether components go flush to edge of these 8mil outlines in the tDocu layer, or do they align with the center line, which would make the components 4mils thinner on each side than they appear in the layout?

Thanks

macegr
Posts: 380
Joined: Wed Feb 27, 2008 4:44 pm

Re: Alignment of Component Outlines in Eagle

Post by macegr » Wed Jan 23, 2013 2:40 pm

When mechanical dimensions are so critical, you need to check everything yourself. You know what size an 0402 resistor is, and you can easily measure the outlines in Eagle.

beebo
Posts: 6
Joined: Fri Mar 25, 2011 3:07 pm

Re: Alignment of Component Outlines in Eagle

Post by beebo » Wed Jan 23, 2013 10:06 pm

Perfect...I hadn't thought of that.
Cheers

beebo
Posts: 6
Joined: Fri Mar 25, 2011 3:07 pm

Re: Alignment of Component Outlines in Eagle

Post by beebo » Thu Jan 24, 2013 10:01 am

For the record, it appears that the outside of the outline shows the max dimension of the component (nominal dimension + buffer)...at least for the parts I looked at, which include the SO8, and 0603 packages.

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