Hi James,

volume density=area density/thickness

therefore:

thickness=area density/volume density
area density=volume density*thickness

Using Josef's numbers, we have:

thickness (in feet)=area density (oz/ft2)/8910 (oz/ft3)

For 1 oz/ft2, this gives 1.12e-4 feet or 1.34 thousandths of an inch
(just about what I had).

To put the formula itself into thousandths, multiply by 12000:

thickness (mils)=1.35*area density (oz/ft2)

The reverse formula would then be:

area density (oz/ft2)=thickness(mils)/1.35

Sean


On 6/22/07, James Newton, Host <jamesnewton@piclist.com> wrote:
> > >How does one convert oz/ft2 into mils as it relates to the
> > thickness of
> > >copper on a PCB?
> >
> > It should be converted thru copper density, which is 8 920
> > kilogram/cubic meter = 8 910 oz/ft3.
>
> Errr.. Huh? Yes I really am that dumb when it comes to this sort of thing.
>
> Let me try again:
>
> If I have copper thickness in mills, what mathematical formula yields
> oz/ft2?
>
> If I have copper thickness in oz/ft2, what mathematical formula yields
> mills?
>
> > >to add that feature for the other unit selectable fields,
> > one of which
> > >is
> > >oz/ft2 or mils for copper thickness.
> >
> > Yet another way is thickness in micrometers.
>
> K. Give me a set of formula and I'll add another option.
>
>
> Thanks for trying to help.
>
> ---
> James.
>
>
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