Homebrew PCBs

Dne 12.1.2012 11:01, pi\ufffde DJ Delorie:
> Slavko Kocjancic<eslavko@...>  writes:
>> Does someone know what energy is nedded to develop photoresist?
> Here's an example:
> http://www.thinktink.com/stack/volumes/voli/store/specs/m115spec.htm
>
> The key parameter is "energy" in mJ/cm2 (millijoules per square centimeter)
>
> To truly calibrate a system, though, you need to do a test exposure
> through a transmission step wedge, like:
>
> http://www.stouffer.net/TransPage.htm
> http://www.thinktink.com/stack/volumes/volvi/filmimag.htm#Calibration
>
> The wedge allows you to do a range of "exposures" at one time, and since
> it's calibrated(ish) the results tell you what actual exposure to use.
>
> For example, if you do a test run at 10 cm/sec laser travel, and the
> results are "held at step 10" but the resist says it wants step 8, and
> you're using a 21-step wedge (1.414x per step), you need to double the
> laser speed to 20 cm/sec or cut the energy in half.
>
>

With data on this page and One I already have the exposure needed lies 
somewhere in 350 to 1000mJ/cm2.

So here is my asumption.
For worst film (1000mJ/cm2) = 10mJ/mm2
and UV LED (350 MCD, 12mW) focused on 1mm2
give me that spot must be exposed for 1 second, ie sped should be 1mm 
per second.
Is it that calculation correct?

Slavko.