* Need an insolation box
* Number of step for the process
== Components ==
=="Toner transfer" PCB etching==
* http://www.riccibitti.com/pcb/pcb.htm* Test print design : [http://www.dr-lex.be/hardware/hwimages/toner-design.png]
==Photoresist PCB Etching==
===Parts===
*Uv light (UV LED strip or DIY UV LED fixture?)*Pre-coated photoresist positive pcb*Lye (NaOH)*Ammonium persulfate(or Ferric Chloride, available at Fixme hackerspace)
===PCB Layout===
Remove the plastic protection on the PCB. Place the printed side of the layout against the copper side of the PCB. Remove the air bubbles captured under the greased paper
Place the PCB & Layout inside the exposure box. Then let the UV light do the work for 3-4 2 minutes 30 seconds ''This is a '''completely arbitrary''' timing, we should test different values''
Remove the PCB & Layout from the exposure box
===Etching===
The etching solution is a 200g/L ammonium persulfate mix(or Ferric Chloride).
The etching process can take to over an hour. To speed up this shit, you can add heat and/or bubbles to the solution.
The reaction is (NH_4)_2 S_ 2 O_8 -> CuSO4 + (NH4)_2 SO. The resultant liquid is less harmful than ferric chloride but should still be treated with other chemical waste
== Photoresist etching with Sodium Persulfate ==
# Print inversed PCB on two layers of transparencies, and make sure that there is visible text to be able to identify the side later
# Place glossy side of transparency on the glass of the UV exposure box, and the matt side (with the toner) face up - you should be able to read the text inverted now
# Peel back the protective film from the pre-sensitised PCB, and carefully place it over the transparency
# Expose for ~3 minutes (time needs to be experimented with still), with a weight (such as one of the bottles) on the cover for pressure
## Whilst the PCB is getting exposed, pour 1cm worth of soda (french: soude) into a container
## Prepare another container with just water, to rinse of the soda
# Remove PCB from UV exposure box, and place into soda solution. Stir and agitate until the soda and PCB until there are no more violet traces that leave
# Remove PCB from soda solution, and rince off with water in other container - use plastic tweezers to handle it
# Attach PCB to support wire, and place the PCB into the Sodium Persulfate solution, and wait until you can see the resin (should take ~20 minutes)
## Whilst waiting, pour the soda back into its bottle, and rinse the containers
# After you can see the resin, remove the PCB before the traces get etched away, and rinse it off
# Pour Sodium Persulfate back into its container and clean up
(photos to come)
== Safety ==
== Schedule ==
* 15 13 décembre 2012: First workshop[[http://www.doodle.com/8fyynphtyzyi8ika Doodle ]]
== See Also ==
* [[PCB_Fab]]
* [http://www.engscope.com/pcb-fab-tutorial/ Fairly in depth tutorial]
* [http://nononux.free.fr/index.php?page=elec-brico-outils#!elec-brico-outil-largeur-piste-pcb Outil de calcul de largeur de pistes]
== Participant ==