Re: ground perforations in two-layer boards

["Daniel DeConinck" <daniel.deconinck@sympatico.ca>]

Hi Jim,

You wrote ,  "...The longer time  to etch is of coarse on the heavier copper
side"

Isn't it the other way around ? A side which is all copper (or mostly
copper ) does not need to etch (or etch much).

Also I do not neccessarily understand the ethcing process well enough to
understand this explanation. To simply say a side with less copper takes
longer to etch doesn't explain it for me.

Example:  A turkey cooking time is based on its weight. But if you have more
than one turkey the time is NOT based on their cumulative weight.
You see I thought etch time would be related to the thickness of the copper
( and the strength of the etchent / temp / agitation/etc.. ) and not the
area of the copper. Well I guess there are also some edge effects where
copper will etch faster near its exposed side since its is being attacked
from both the top and edge. See what I mean. I just see many variables and I
need a more detailed explanation.

Could this issue be related to warpping of the PCB.

Sincerely
Daniel DeConinck
www.PixelSmart.com
TEL: 416-248-4473