Not able to connect SMD pads to a ground plane
Posted by simonbr at
Hi,
I am designing a 4 layer board with SMD components in DesignSpark PCB. One of the inner layer is defined as a power plane. Of course, to go from a SMD pad to a power plane you need to connect the SMD pad to that plane using a via. Now some pads can be autorouted, but on other pads the autorouter does nothing.
And I haven't found how to connect an SMD pad to the power plane manually. If I make a track from the SMD pad and change the layer to the power plane, DesignSpark PCB inserts a via but does'nt let me stop there.
See the attached picture. I have highlighted the GND net so all the pads assigned to GND are shown in blue. The GND pads of R2, R3 and C1 were autorouted and they are connected to the GND power plane. But the blue pads on U1 won't autoroute, and I also can't manually connect them to the power plane.
Can someone please explain how to do this?
Best regards
Simon Brouwer
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- elusive-groundplane.png (10.09 KiB) Viewed 293 times
Replies
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OK, answering my own post with some additional information...
I found that if I choose a really small track width for the net class Ground, some smaller pads will be autorouted as well, but still not the smallest pads. Somehow the autorouter is too picky about where it thinks it can route. But I need it to make the connections to the power plane because I don't know how to do it manually!
In any case I found a workaround: unrouting a track segment to one of those vias that connect to the power plane does not remove the via. I can then move the via close to a pad that I need to connect, and manually place a track to it. Then I can re-autoroute the pad that I took the via from.
Best regards
Simon