Alignment of Component Outlines in Eagle

Community PCB Design
1

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

2

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.

3

Perfect…I hadn’t thought of that.

Cheers

4

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.