Homebrew PCBs

DJ Delorie wrote:
> Philip Pemberton <ygroups@...> writes:
>>    (using Thinktink's numbers as an example) Dry film requires 42.5 mJ/cm^2
> 
> ThinkTink's film requires 150-300 mJ/cm2

Their website disagrees:

"Exposure energy: 25-60mJ/cm^2"

<http://www.thinktink.com/stack/volumes/voli/store/specs/m115spec.htm>

(60-25) = a range of 35mJ/cm^2.

Lower bound plus half the range = 25 + (35/2) = 25 + 17.5 = 42.5 mJ/cm^2.

A quick bit of maths suggests I'm off by a factor of 5 or 6 assuming 
Thinktink's website is wrong...

Unless, of course, I've missed something...

>>    Double that = 1307.58 seconds exposure
> 
> That's 21 minutes.  Sounds about right for an initial step gauge test.
> I'd use 16 just to make the math easier ;-)

And conveniently less than the maximum time my UV box's timer will run for 
(16*60=960; 960 < 999)... :)

Right.. now to print off some transparencies, then I think I'll be building up 
the first part of the GPSDO I've been meaning to build for about three months...

Thanks,
-- 
Phil.
ygroups@...
http://www.philpem.me.uk/