From: Don Pearce
Subject: Re: Ground pours on top and bottom layers?
Date: Wed, 08 Jan 2003 09:56:44 +0000
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On Wed, 08 Jan 2003 02:28:28 -0700, Kevin Kilzer
>On Mon, 06 Jan 2003 23:49:58 -0800, John Larkin
>>On Mon, 06 Jan 2003 22:20:50 -0700, Kevin Kilzer
>>>Speaking of balanced layout...my board shop has (for some time now)
>>>been putting small, isolated squares on the outer layers. These
>>>squares are about 4mm on a side, spaced about 7mm apart. None is
>>>electrically connected to anything.
>>>Opinions, good or bad? We passed EMC/EMI without issue. I did not
>>>oppose it, because they seemed too small to act as secondary
>>I would never use a board shop that altered my artwork for any reason
>>other than to adjust for their process variations. If they did, I
>>wouldn't accept the boards.
>I was unclear. I approved the change to help reduce process
>variation, but my question is about the EMC/EMI issues.
>Will these isolated regions turn into radiators?
>BTW, we specify on the drawing where to put the "Made in XXZ" message.
>Usually we put it under a large component so it will not be visible in
>the finished product. I've had customers demand the 94V/0 logo be
>visible in the finished product, so we specify where to put that, too.
Any pieces of ground pour that end up isolated should be removed. At
best they achieve nothing, at worst they will cause unwanted
capacitive coupling between regions of the board that should not
couple. If possible, ground (or connect to a rail) all these areas any
way you can - vias are quite acceptable.