So germicidal works on negative photoresist and won't work on positiv 20 nor dry film. "need near UV and longwave UV (IIRC)." If I'm understanding this correctly this is mean "near visible light wavelength" right?
Thanks
Hari
-------Original Message-------
From: Harvey White [
madyn@...]
Date: Sat, Feb 23, 2013
To: [
Homebrew_PCBs@yahoogroups.com]
Reply To: [
Homebrew_PCBs@yahoogroups.com]
Subject: Re: [Homebrew_PCBs] Re: DIY pcb exposure box UV tl
On Sat, 23 Feb 2013 10:41:43 -0000, you wrote:
>I don't think so, I think the wavelength is wrong, exposure won't work or won't work properly.
You used Germicidal (bare) lamps with the old Kodak KPR chemistry, a
negative resist.
Current positive films need near UV and longwave UV (IIRC).
NEVER LOOK AT A GERMICIDAL LAMP DIRECTLY
Never look at it except through a red filter that does not pass UV at
all. The wavelength breaks apart proteins in your eyes (and germs)
and can severely damage or destroy your sight.
You can find the specs on what your resist needs, and find UV or the
like fluorescents to do the same. The UV leds are still a bit
dangerous, so do not look at them directly, but they are not as nasty.
Harvey
>
>Never mind that they are much more dangerous for your eyes etc!!
>
>I've been using UV LEDs. Seem to work just fine...
>