🚀 go-pugleaf

In article <12692@sdcc6.ucsd.edu>, dlou@dino.ucsd.edu (Dennis Lou) writes:
|> 
|> It's been a while since I etched a board.  Now, I think I want to do a
|> Radio Electronics project.  They supply the pattern in the magazine.
|> It's too intricate to just lay down transfers on copperclad and I
|> don't want to spend the time and money to buy the board outright.  I
|> assume the best way is to photoetch.

|> So my question is: What's the best way to photoetch a board assuming
|> you etch boards on a limited basis and you only have access to
|> basement materials/facilities?

I have had good success with UV sensitive resist and a photolith of
the PC pattern. I used to use a spray on resist that would develop in
a weak Sodium Hydroxide solution. I have been told that this is no longer
available due to a carcinogen scare. Pre-coated boards are generally
available and don't seem too pricey. Need special developer.
Here at Adelaide Uni the students association does a lot of printing
(leaflets, whats on sheets etc) and have an in house process camera. 
They are happy to make a photolith film at essentially cost price. You 
may be able to find someone on your campus to do the same. The lith 
is the most costly part of the excercise. They can do either positive
or negative depending on the needs of your resist process. Commercial
printing places charge lots for this service.

I built a simple vacuum board (a thin flat box with grooves on the top
and holes in the grooves that penetrate into the box, and a hole in the
bottom of the box to connect to a vacuum cleaner, a few minutes work
if you have a router, a bit longer if you have to carve the grooves 
(about 1/8" wide and high)) onto which I place the coated board and then
the artwork and then some cling-wrap. Start the vacuum and the whole lot 
goes very solid. Expose. I expose in the sun, (about 3 minutes in bright
sunlight) or you can buy an appropriate lamp. If you try the sun you
should do a few trail runs to get the exposure right for your combination
of chemicals and weather. The results I have had have been consistently
better than bought boards. It only remains to drill the board. (Get
a tungsten carbide drill bit.)

Hope this is of some help.

							Francis Vaughan.