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T O P I C    R E V I E W
shadders Posted - 08 Sep 2010 : 08:55:45
Hi,

In applying copper fill areas, i have a number of isolated copper filled areas. The larger fill areas i have used a Via to connect to the power plane/copper layer below the filled area.

For others, there is no connection to the equivalent Net directly below - as this may be the wrong plane.

Hence, leaving the isolated copper fill areas unconnected to another voltage potential such as ground, will produce a capacitor.

Is this a problem ?. Can a voltage build up on these areas ?.

I assume best practice is to remove such isolated copper fills ?.

Thanks and regards,

Richard.
5   L A T E S T    R E P L I E S    (Newest First)
shadders Posted - 08 Sep 2010 : 16:03:11
Hi Iain,

Thanks - i did a quick calculation using basic capacitance formula - a few mm^2 has a reasonable pF value - which as you have stated is an antenna issue.

Regards,

Richard.
Iain Wilkie Posted - 08 Sep 2010 : 15:30:13
If floating copper is seperating tracks , it can couple these togerther. Also they can act as antenna.

We did a lot of work for a radio application client and they insisted that there be no floating copper !

Iain
shadders Posted - 08 Sep 2010 : 14:23:07
Hi,

Thinking about the voltage build up - don't think this is possible - since there is no connection to supply excess or deplete the electrons in the copper shape.

It may act as a capacitive coupling but i don't think a voltage can appear permanently.
Regards,

Richard.
shadders Posted - 08 Sep 2010 : 11:38:25
Hi Iain,

Thanks.

Regards,

Richard.
Iain Wilkie Posted - 08 Sep 2010 : 11:17:00
Richard,

I have always done the pour to remove these isolated areas. Generally yes it is bad practice to have floating copper areas.

Iain