SparkFun Forums

[60amp_relay]

Hi guys,

This has got to be a simple problem, but for the life of me I can't figure out how to solve it. I'm trying to layout a PCB in Eagle that has both 0.65mm (TSSOP) and 50mil (SOIC) surface-mount parts. The autorouter only lets me pick one or the other. If I use 0.65mm, then the TSSOP traces line up perfectly with the pads, but the SOIC parts all have the traces shifted off-center from the pads by a small amount. Vice versa if I use 25mils - the traces line up perfectly with the SOIC pads, but the TSSOP traces are all off-center from the pads.

How can I have the autorouter line up the traces with both the 0.65mm- and 50mil-spaced pads?

[monstrum]

50 mil is 1.27 mm so you need a grid that works for both 1.27 mm or 0.65 mm. If you absolutely need it to center traces to all pads, you will have to use a routing grid of 0.01 mm. That will be very slow but if you can accept that the traces are off by a little you could try a grid such as 0.1 mm or maybe 5 mil (0.127 mm). It will probably be good enough.

If you don't use the autorouter the traces always centers at the pad if you origin the trace from the component.

[60amp_relay]

That worked perfectly! By setting the autorouter to 0.02mm, it gets the traces centered nicely on all the pads. Thanks for the suggestion.

[monstrum]

Glad I could help. Just be aware that using such a small grid when routing complex boards usually takes an eternity. You might have to increase the grid and manually re-route the traces to the pads to get them centered.