Rob,

As AJ points out, part of what they say is correct, and you do need to
"balance" the layers, and the primary reason is to prevent "warpage" and
related problems.

However, the remaining issue, is raising a "flag" about your boardhouse.

Most boardhouses today use equipment that continually "sprays" the etchant
on the surface of the board, and hence also washes away the "etched copper".

Some boardhouses may still "dip" or submerge the board into an "etchant
tank", where the board simply sits in the etchant, however, there should be
enough "agitation" or "circulation" of the etchant to prevent what they are
describing from happening.

What they are telling you is that they simply "dip" your board into an
etchant tank and leave it there, with no "agitation" or "circulation",
which, yes, will cause the symptoms they describe.

But they are also telling you that they are not making your boards properly
and that you should be looking for another boardhouse.

JaMi

----- Original Message -----
From: <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Tuesday, October 08, 2002 9:50 AM
Subject: Re: [PEDA] OT - Complex boards and time to Layout?


> Interesting, I thought that the copper "balancing act" was only for
> containing possible warpage. Makes sense, though. Thanks for tip.
>
> aj
>
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> >...
> > I did this type of pour and had the board house
> > slap my wrists ...The explanation was that if
> > you have a big pour with lots of copper on one
> > side you need about the same copper on the other
> > side to balance it. Otherwise the acid on one side
> > gets weak while the other side remains strong,
> > resulting in overetching on one side or
> > under-etching on the other

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