🚀 go-pugleaf

In article <885@kodak.UUCP> ornitz@kodak.UUCP (barry ornitz) writes:
>In article <2392@uwmcsd1.UUCP> neighbor@csd4.milw.wisc.edu.UUCP (Jeffrey Alan Ding) writes:
>>
>>Hello.  Does anybody out there etch PC boards?  I have a kit from
>>GC electronics that uses chemicals to transfer a pattern onto the PC board.
  ...
>>I'm wondering if anybody out there has used this stuff.  I'm having a bit
>>of trouble photo sensitizing my own PC boards.  I've tried the process
>>with PRE-sensitized boards and it works great.  But the boards that I
>>sensitize do not work at all.  If any of you have any experience doing
>>this I would appreciate any info on how to make it work.  Oh one more thing,
>>I'm using POSITIVE method.  There are both positive and negative methods.
  ...
>I have rarely had any luck using the spray-
>on resists sold by GC, etc.  This products rarely sells quickly and is useless
>if overheated in the can.

I have used the GC negative-acting photoresist with excellent results, but I
had a fresh can.  I guess I was lucky!  What Barry says is true about its
aging properties.  I have learned that if the spray comes out a dark purple
color, then it's OK.  If it comes out yellowish, it's shot.  Another important
thing is extreme cleanliness of the board being sensitized -- this means taking
scouring powder to clean any oxidation and oil off the board.  Use 600-grit
wet emery paper or steel wool if necessary.  I don't like steel wool for the
bits of steel it leaves behind.  That board should positively GLEAM when you're
done.  Then, handle it only by the edges -- the oil on your fingers is enough
to screw up the photoresist.

-- 
Bob Hoffman, N3CVL       {allegra, bellcore, cadre, idis, psuvax1}!pitt!hoffman
Pitt Computer Science    hoffman%pitt@relay.cs.net