Using 12 mil traces and 12 mil isolation on the ground plane. Dry film etch resist via wet lamination with lot,iron, and ferric chloride on a sponge. Exposing in a UV box for 1m15s. Developing in sodium carbonate and removing the resist with acetone.
http://i59.tinypic.com/33y6fec.jpgEven at 12 mil, I get occasional microscopic bridges. Literally using a microscope to correct them.
I have a brother printer, toner transfer seems to work mediocre at best. I haven't tried it since switching off of copper chloride. The copper chloride left it super pitted and undercut.
Copper chloride I am finding has too many variables to use consistently. Was using a home made vertical bubble tank with an aquarium heater and it was taking 20-30 minutes to etch. Occasionally would add more HCl or let it rest to regenerate to that emerald green color. Only using about a little of solution, maybe more would help. Very random results. A spray tank it'd probably work amazing but those are cosrtly.
Anyway - any recommendations on avoiding bridges? It seems related to how long I spend developing. More care on that step helps a lot, mostly rubbing and rinsing. A toothbrush occasionally knocks off traces so I stopped with that. Anything better to use for developing? Should I cut exposure time down even more?
I'm getting better at the board making, but when I go to solder it I bridge everything and make a mess. Tried uv cure solder mask, which works really well, but its messy and impossible to get it to look good. Dry film solder resist seems really expensive.
And the drilling.....ugh.
I'm half tempted to just ship this off to China, dirtypcbs or something.
Any suggestions for process improvement?