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Subject: Re: uv resin for a photoresist substitute

From: wa4qal@...
Date: 2017-03-02

Yes and no, with regards to using a UV resin for a photoresist.  The original popular photoresist was KPR (Kodak PhotoResist):

https://en.wikipedia.org/wiki/KPR

That photoresist is UV sensitive, and will harden when exposed to UV light.  Then, it is developed with KPR-developer, a rather nasty mix of volatile and toxic materials (Xylene?) (although I think I remember that safer, alternative developers were available at one point).

The largest problem with KPR is that it is a "negative type" photoresist, in that you need to UV expose the areas which are going to leave Copper.  The world has been searching for an effective "positive type" photoresist for decades.

Now, I haven't tried to obtain any KPR for about 35 years.  I know that, at least at one time, it became quite difficult to obtain.   I'm not sure of the availability now, though.

Dave