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Currently designing a PCB I find out there are some copper island. I was wondering if we should better keep them or remove them and why ?

Is there any manufacturing risk of having those ?

Part of a PCB design

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    \$\begingroup\$ You could remove it and have the trace above the island and follow the same path as the one below it. That would eliminate this island and expand the triangular one above it. From a manufacturing point of view there is no risk of keeping it. \$\endgroup\$ – electrophile Sep 13 '16 at 8:49
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    \$\begingroup\$ Argument to remove: they can act as unintentional receives and then as emitters, causing a whole raft of EMI/EMF issues. Argument to keep: you are too lazy to tick the "remove isolated islands" on the flooding tool of your PCB layout software - They are easy to remove and supply no benefit, so remove them. \$\endgroup\$ – Puffafish Sep 13 '16 at 8:49
  • \$\begingroup\$ @Puffafish, this is what I was thinking and was searching for confirmation about. Thank you \$\endgroup\$ – chris Sep 13 '16 at 8:51
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    \$\begingroup\$ A copper island is copper that the PCB manufacturer doesn't have to etch from the board, so using less chemical and generating less effluent. It's copper that stays on the board, so better board thermal conductivity. Depending on the frequencies involved (but they'd need to be high) it could be parasitic C and L components that wreck the performance of your design. There is no one answer. \$\endgroup\$ – Neil_UK Sep 13 '16 at 8:57
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Yes, you should remove it in most cases, because it can act as an antenna or cause other problems.

You can do this in Altium by selecting the 'remove dead copper' check box.

enter image description here

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If you use high frequency signalling nearby then these islands may cause some kinds of interference (crosstalk, coupling, inductive effects...). In this case it's better to via them to your GND plane.

In your specific picture you can get rid of it by moving the trace (which is north of your island) downwards slightly to take up the space occupied by the island, the island will then vanish.

If you are using no high frequencies then it will most likely not be a problem.

Alternatively, you can always ask your board fabricator to remove unconnected islands from your Gerbers before manufacture. This kind of thing is a common request and they probably won't charge you for it.

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  • \$\begingroup\$ Thank you very much for your highlighting. Your explanation is very clear and understandable. We have removed all dead coper by clicking the checkbox in the polygon of Altium. \$\endgroup\$ – chris Sep 13 '16 at 8:58

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