Homebrew PCBs

Hello Dale,

  Saturday, February 24, 2007, 5:10:28 AM, you wrote:

> Sunlight.

  Nonconstant UV-A radiation on hourly basis.

> Short wavelength UV doesn't pass through glass very well.  The good UV 
> bulbs are made of quartz, hence they're kinda pricey.

  Short  UV  has  nothing  to  do with photoresist on copperclad. Peak
  sensitivity of photoresist is somewhere around 340nm what stands for
  'long wave UV' aka UV-A.

> I've done boards in sunlight with some success.  The trouble is, the 
> amount of UV you get from the sun varies widely from day to day and I 
> think humidity eats it up.

  For  my  prototypes I use Philips UV tubes for reprography. they are
  marked  'somethinginhere/05N'.  Won't  harm  your  eyes,  and  this
  wavelength  of  UV  is  passing ordinary window glass. I'm using 6mm
  (1/4")  piece  as  it  is heavy enough to make enough pressure to my
  repro films or vellum.

-- 
 Best regards,
 Zoran A. Scepanovic
 zastos@...

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