Hi,
I have two ideas for home made soldermask, would like to hear
comments. I have not tried any of these but they have promise.
Idea A (Toner Transfer on to Pads):
1. Toner-Transfer image to PCB, etch PCB
2. Use acetone or something else, remove all toner
3. Do a second toner-transfer pass, this time transfer toner only
onto ∗PADS∗ of component (i.e. solder paste layer)
4. Spray the conformal coating(soldermask material) over entire PCB
and let it dry
5. Use acetone and gently rub to remove toner on the pads; even
though there is a conformal coating, it is on top of the toner, so the
toner could be undercut
- One variation is instead of transferring onto the pads with toner,
use inkjet ink or something that doesn't really stick but rests on the
surface of the pad
- A second variation is to Toner-Transfer the solder mask onto the PCB
and use a laser transfer foil
Idea B (Vinyl cut a solderpaste layer):
1. Toner-Transfer image to PCB, etch PCB
2. Use acetone or something else, remove all toner
3. Use a vinyl cutter and either with thin copper foil or heavy duty
aluminum foil cut out pads for the design (i.e. solder paste layer)
See links below for some background
http://fab.cba.mit.edu/content/tools/machines/roland_vinyl_cutter/(bottom part of this page for really thin copper sheet)
http://www.whimsie.com/coppersheetwire.html#anchor453915. Overlay copper foil on PCB
6. Spray some solution that can be easily removed on the pads, maybe
latex or the Testors Solution ("temporary block")
7. Remove copper foil and spray actual conformal coating and let it dry
8. Rub the board and remove the "temporary block"
∗ Note, the same foil (or a new version) could be used to put solder
paste on the pads for easy SMD assembly!
What do you guys think?
I'm also curious if anyone tried the Direct-PCB inkjet technique and
was able to get a soldermask out of it.
Thanks