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re-routed PCB layout

houandreas

hi, thanks to you guys for the suggestion. I did some pin swap in schematic and rerouted the PCB manually. It took me 2 days...Default DRC passed. Below is the result.

Net classes: signal traces 10mil, via 20mil, clearance 10mil; Power traces 24mil, via 20 mil, clearance 10 mil. I did some research on this and I think this is enough for my design. But still, I'd appreciate it if you could give more advice. Traces in the central part are so crowded. Some traces on bottom and top overlap, idk if it will be a problem.

I add some vias to connect top and bottom ground plane. But those are smaller (14mil drill) than in my net classes. So the DRC warned me. Can I ignore this?

imageimageimage

  • Hi Bin,

     

    That's looking much better. I think its ok even if the center is crowded. The design rule values you mention sound reasonable too.

    14mil drill is quite small (0.355mm) but not crazy-small. But low-cost PCB factories may not want to go that small. They may auto-correct it for you, but better for you to do it yourself, maybe try 0.5mm or 0.6mm in most places, since you have the space. Only when you're using surface-mount chips or some super dense board, might you need to go smaller than that.

    Here are some tricks for you in the crowded area, if you find your current method does not allow you to increase from 14mil drill.

    In this example, the holes are just over 19mil drill size, i.e. 0.5mm drill, and the track width is 8mil.

    image

  • in reply to shabaz

    hi, shabaz, thx for your advice. image The tricks you showed me is useful, I also realized this when I was routing, to stagger the location of vias. I will route like this next time. Though I can use bigger via in central area, I don't see a possibility to use them on the LPC connector area. So I guess the price would be the same either I have 1 or 10 smaller vias? If it were a product board then it would be good to use bigger via wherever possible.

  • in reply to houandreas

    Hi Bin,

     

    For the low cost PCB manufacturers they charge just a fixed price, no difference. They may not like 14mil hole however, if your traces have not left room for them to make the hole bigger.. better to try 16mil, they may be happy with that, but ideally at least 19mil.

  • in reply to shabaz

    Hi, shabaz, good to know this. I changed those vias to 0.48mm. So many thx for your help.