Homebrew PCBs

Marc Sulfridge wrote:
> The problem is one of units.  The first number you calculated is the lamp
> intensity in W/cm^2=J/(s*cm^2).  Your dry film dose is specified in
> mJ/cm^2= 0.001 J/cm^2.  You need to convert this to J/cm^2 to keep your
> units consistent.  42.5 mJ/cm^2 = 0.0425 J/cm^2.
> 
> Thus: time = 0.0425 J/cm^2 / 0.065 J/(s*cm^2) = 0.654 s
> 
> doubling this gives 1.31 seconds.

Which seems even more off than my estimates -- other types of photoresist I've 
looked at specify an exposure time of between two and three minutes.

The only time I can see a one-second exposure working is if the light source 
was an arc lamp...

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