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