Published: Friday, 20 June 2014
Written by Jon Chandler
It's desirable that connections to pads on a circuit board are correctly aligned to the center of the pad. A few tips follow to aid in doing this.
Difficulties arise when pads are not on the selected grid in Eagle. This can happen when mixing parts with imperial and metric units or when it's required to position a component to align with a panel or another board.
The illustration to the right shows the ideal case for a DIP package. The pad pitch is 0.1" and the grid spacing is 0.05" as shown by the faint gray lines. The traces intersect with the center of the pads.
The figure below shows what happens when pads aren't on the grid. In this case, there's a DIP package with 0.1" pitch pads and a header with 2mm pitch. The grid is set to 1mm and the header is aligned to the grid. The connections to the header align with the center of the pads.
The connections to the DIP package don't align well. Every other connection is so far off, the trace connects to the edge of the pad. This can result in clearance problems, particularly when traces are run between pads, and a weak point where the trace and pad intersect.
Read more: An Eagle Tip: Routing Traces to Pads
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