Homebrew PCBs

I just finished up my new photo resist spinner.

  Its consists of a plywood box  15" square and 3" high with a modified
surplus computer fan mounted in the center.   I found a nice 4" Nidec
fan with a metal frame and cut off the plastic blades with my band saw. 
Also took off about 1/2" of the metal frame to allow the fan hub
protrude above the frame.   I used some JB-weld to glue a 6" aluminum
disk to the fan hub.    I mounted a push button swithch in the side and
power it with a wall-wart transformer.

I posted a picture and a short video low quality video clip at: Spin
Coater <http://picasaweb.google.com/cschaffter/DYIPCBs#>

The board is fastened to the aluminum plate with small loop of masking
tape.   To coat the board I put about 1/8 tsp of the resist on the board
and spread it out with my small brush or my finger.  This wets the
copper and prevents dry spots when spinning.  Then I add another 1/8 tsp
in the center and turn on the spinner.    I use the power button to
modulate the rpm and stop the process by eyeball.

I just started playing with the Genesis AQ3000 waterborn negative photo
resist and so far I like it.  I am getting a nice even coating from the
spinner and after baking at 180 deg F the resist is nice and hard with
good adhesion.   No worry about pulling off the resist with masking tape
while doing the second side.   I have not etched a board yet but did a
test exposure yesterday with an old circuit negative.   I think the
resist is quite sensitive,  but I will know more when I get my UV box
built and receive my Stauffer  21 step test strip.

Next project will be to build the UV exposure box from a couple of 36W
nail polish curing units off ebay.    UV lamp
<http://stores.ebay.com/eTech-Digital-World__W0QQ_sidZ863785197?_nkw=36w\
&submit=Search>

Craig







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