1. I learned from FUKUDA Copper Foil that basically
reduced drum speed 10% can gain 10% copper basis
weight (Thickness);
2. How thin is too thin really depends on the
designer. Some designers still consider 1 OZ copper
foil thickness is 1.4 mil and I bet they don't know
copper thickness should be measured by basis weight.
The typical minimum (electrical) thickness of 1 OZ
may as low as 1.1 mil (from shining side to the bottom
of copper foil profile), consider the mat side profile
of standard copper foil could be 10 um for 1 OZ;
3. My data is average thickness of copper foil on the
market is about 6% lower than nominal. If you still
consider 1OZ as 1.4 mil or 1.35 mil, the copper foil
will be too thin anyway, regardless you only remove
about 1 um by microetch.

Hope it helps
Shirley






--- Earl Moon <[log in to unmask]> wrote:
> Shirley,
>
> For some of us less informed, no joke, could you
> explain the ED foil process
> and how such things as drum rotation speed affects
> thickness. Also, if you
> can, please explaing various processes used to
> prepair outer layer foil
> surfaces for subsequent cleaning, imaging, plating,
> and etching processes.
> I'm especially interested in how thin is too thin
> under what processing
> conditions.
>
> Thank you much,
>
> Earl
>
>
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