Homebrew PCBs

> > What's the power requirement to expose a photosensitive board?
> >
> > Remember a 5000 millicandela LED will focused down to a 0.0254 mm point.
>It seems to me someone

It was me, Stevens. Here you are the calculations:

My calculation is  like this:
For a board of 10x16 cm=160 cm2.

If all need exposured (maximum, no traces at all), it need 16000 mJ.

A 100 mW  beam (laser, or whatever) it needs 160 seconds exposure to get 
16000 mJ.
that is 2.6 minutes, a 25 mW laser will take about 10 minutes.

If the requested polymerization energy of 100mJ/cm2 is correct,
the above calculation is correct.

More than that, I've found that the energy is around 50mJ/cm2 for a lot of 
suppliers and
the peak spectral response is on 400nm.


>calculated all this in the past and it came out
>to taking a ridiculously long time to expose a board this way.
>
>Steve Greenfield



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