RE: gEDA-user: PCB: mesh style plane?

["Robert Thorpe" <Robert.Thorpe@xxxxxxxxxxxx>]

> -----Original Message-----
> From: owner-geda-user@xxxxxxxx 
> [mailto:owner-geda-user@xxxxxxxx] On Behalf Of Karel Kulhavy
> Sent: 30 August 2005 10:10
> To: geda-user@xxxxxxxx
> Subject: Re: gEDA-user: PCB: mesh style plane?
> 
> On Mon, Aug 29, 2005 at 02:09:31PM -0400, 9000 VAX wrote:
> > Hi, list,
> >   I found that my two-sided board curved a little bit 
> toward the side 
> > with more copper plane area, maybe due to the tension in the copper 
> > plane. I think mesh style plane other than solid plane 
> might solve the 
> > problem. Does PCB support this feature? Thank you.
> 
> Then it's probably something wrong with your process. I make 
> boards like this and the company (Pragoboard, Prague, Czech 
> Republic) always delivers them perfectly flat.

FR4 boards do this if you have a big board with a great amount more
copper on one side than the other.  Putting copper mesh on the other
side is a common method of avoiding it.

Sometimes you can live with a little warping, sometimes you can't.  The
amount of warping you get depends on the thickness of the copper layer
and the FR4.  I think sometimes heating it can make it worse.