DIY solder mask theory (And a big one, need helllllpppppp)

[frank]

My wax pad masks took me 15 min. to do on the ROG Eighteen  .
But I am stupid and sprayed polyurethane .
Well, should have thinkd before, that bees wax is soluble in those solvents . 
I should read more psychology mag and listened to my little intern voice (it said don't do that idot)  .

before =  :


now = :


Conclusion: water based lacker should be OK.

[darron]

i've bought two sprays to play with. one is a small can used to spray glass (which is what the pcb is anyway), which is a semi-transparent blue. it doesn't say what it is made from. i tried it on a pcb and it worked great. the solder didn't seem to bother it and the flux just melted over the top of it. the other is a candy-apple red which worked jsut as well, but cost 4x. blue looks prettier too.

i'll try to get some pics up of a properly populated board and solder mask.

[frank]

I have removed the wax.  At some pads the limits are very neat.  But at other places, big chunks of polyurethane pealed off.  What a mess.... breaks my heart to throw that PCB in the trash. Gonna take a break I am    .

[frank]

Did not work with water based acrylic neither. The wax was trapped underneath the layer of paint.  When The PCB was put at heat so the wax could melt, the acrylic stayed there.  When I rubbed a bit to remove the hot wax, everything started to lift and peal.  I think my experiments are going nowhere.

[jpm83]

Would this be useful in this thing? http://www.dickblick.com/zz217/11/

Janne

[darron]

Would this be useful in this thing? http://www.dickblick.com/zz217/11/

Janne

probably as useful as any other clear. if you've got some then give it a shot? (:

[R.G.]

The thread sealant used on water and gas piping is impervious to water and petroleum solvents like paint thinner and such. It dissolves in alcohol.

A useful technique might be to use a brayer to roll a layer of this gook onto a sheet of window glass, then use the eraser on a wooden pencil to stamp a round "not here" covering on each pad of the PCB. The passivating spray could then be one impervious to alcohol and you could wash off the pad coverings with alcohol.

Still a lot of work.

[frank]

After my bad experiments, I think that what would perhaps work, would be a kind of alcohol based lacquer or shellac.

One thing that is sure is that the paint should:
1- Contain no solvents that can dissolve wax
2- Can be sprayed as thin as possible
3- Once dried, would be "brittle" so it could break easily around of the wax "islands" when the wax is removed.

If you think of something tell me, I cleaned the "testing PCB".

Do you think that instead of the wax you could put finishing nails in the holes?  The head of the small nails would act like small pad masks.  Then you spray and remove the nails.  It would also be faster......no ?

[MarcoMike]

toothpaste/spraypaint?

[jpm83]

One thing that crossed my mind is to use a hole punch http://upload.wikimedia.org/wikipedia/commons/a/a5/Hole_punch.JPG to make small sticky pads from contact paper
http://housewares.hardwarestore.com/37-188-contact-papers/clear-contact-paper-105240.aspx and put those on the pads.

Janne

[frank]

toothpaste/spraypaint?

Is it a tested advice or I will screw up again.

[R.G.]

I don't know about you, but I will *always* screw up again. 

[MarcoMike]

well, it was just the first (maybe second) idea that came through my mind...

the first one was some kind of cookie dough... any sticky, water-based material....

thinking back to it, cookie dough looks even more promising: you can bake it after painting and its expansion may help the separation step...

do as scientists would do it: find several masking materials, apply them all on the same sample, spraypaint the sample and see which one works better, you may screw up only once!

[frank]

I think I am at the "finishing nail option" step.  After that I will have the hammer in my other hand...

[frank]

The thread sealant used on water and gas piping is impervious to water and petroleum solvents like paint thinner and such. It dissolves in alcohol.

A useful technique might be to use a brayer to roll a layer of this gook onto a sheet of window glass, then use the eraser on a wooden pencil to stamp a round "not here" covering on each pad of the PCB. The passivating spray could then be one impervious to alcohol and you could wash off the pad coverings with alcohol.

Still a lot of work.

Oh no Mr Rg,
you gave me a new idea.
Think that it is my destiny to pass trough this mask karma.

[therecordingart]

I know I'm resurrecting an old thread, but Humiseal makes a solderable conformal coating. Etch/drill your pcb, spray it, let it dry, start soldering.