Renewable Energy Questions/Discussion > Automation, Controls, Inverters, MPPT, etc

Anyone photo etch PCBs? Help!

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madlabs:
Hi All,

Decided to try my hand at photo etching PCBs. My buddy with the CNC router has been flaking and I want to get my new alt charge controller on a baord.

I am using the Datak system. The procedure is to spray the boards with photoresist (in a darkroom) then dry 'em in the oven (keeping 'em dark in a tin) then expose 'em to UV light (~ 3 mins) with the artwork on top. Then develop them, 30-40 seconds in one tray, dry, then another 10 secs in another tray.

I follow the instructions to the letter, but I am getting only the faintest of patterns. My last one I set the bulb closer and got no pattern at all, so maybe I'm over exposing. Going to try to reduce the UV on the next try.

Any ideas what it means to get no traces or almost no traces? And does the developing need to be done in the dark? My instructions don't say, but I have been assuming yes and keeping it dark.

Thanks!

Jonathan

Wolvenar:
I just use the old trick of a  heavy laser print on glossy catalog paper..
Iron that image to the board, take the paper off under running water, then etch.

Works pretty well most of the time.

madlabs:
I have tried toner transfer for years, the thing is that it is erratic, sometimes great and sometimes not. And the more complex and finer traces the harder it gets. While phot etching is PITA I'm hoping for more consistent boards.

But right now I'm not getting any boards. :(

Bryan1:
Hi Madlabs,
                 I too use the glossy paper for my pcb boards and just use an iron to transfer the image, now the trick is only use thick glossy paper like the heavy grade glossy paper business's use for flyers. Avoid any images and ensure the copper board is scrubbed totally clean with a scourer and don't have the iron too hot. I usyally iron away until the image shows thru the paper. I have even ironed on some smd pads etc with 0.4mm traces with great success and one can also convert a laminator over to use for the transfer method too.

              I found printing a pcb image onto a transparency with my laser printer I do need to do do 2 copies and I get mixed results even then so now I just expose UV boards fully so I can then just do the iron on method now.

Regards Bryan

oztules:
I use the Kinsten stuff... cheap from Hongkong ebay.
I use the 15w desk flourescent.
I use a single transparency.
20 min exposure
then NaOH and then ferrric chloride or ammonium persulhpate.

perfect results every time... very fine detail if you want.

I don't like spraying my own resist boards from copper, as it never covers perfectly evenly, and the results are flaky.

Iron on sounds ok, but the kinston is the easiest to get perfect results every time.

Also note from the last PCB in the CDI story, I try to use up all the copper space I can.... saves on etchant. I used to make spider web looking boards.... now as chunky as I can.


....................oztules

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