Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

I cobbled together something that might work. After experimenting with
various abrasion materials I found velvet to be most effective at
removing photoresist in developer. See photo links below.

Top view of my immersion developing tank showing the 200W heater (set
28C), and the velvet/foam stuck to inner walls. PCB is inserted between
the velvet and moved up and down to rub on the photoresist. Takes ~80
seconds to develop.
http://members.optusnet.com.au/eseychell/tmp/dev_tank_top.jpg

Cross section view of padded velvet block. Velvet is made from
nylon/rayon mix. Contact adhesive applied between velvet and stainless
sheet. Two screws fasten the stainless steel base plate to tank wall.
http://members.optusnet.com.au/eseychell/tmp/dev_foam.jpg

Test PCB before developing. Pattern of grid with 0.2mm lines & 0.2mm spaces.
http://members.optusnet.com.au/eseychell/tmp/dev_board_1.jpg

50% developed
http://members.optusnet.com.au/eseychell/tmp/dev_board_2.jpg

100% developed
http://members.optusnet.com.au/eseychell/tmp/dev_board_finished.jpg


A 0.2mm diameter hole incompletely developed. The dark copper is etched,
while shiny copper is covered in resist scum. This problem was caused by
overexposure.
http://members.optusnet.com.au/eseychell/tmp/dev_scum1.jpg

A 0.2mm diameter square hole successfully developed.
http://members.optusnet.com.au/eseychell/tmp/dev_good.jpg

Adam