I want to paint the nonconducting side of the PCBs that I've been making so that when the superflux are soldered to the board the "copper" side of the PCB will face away from the lens of the lights and the LEDs themselves will be on the nonconducting "green" side.
I did an experiment today. I had a few pieces of copper board that I cut off from another board that was going to be etched. I took 2 equal pieces.
Step 1) Both pieces were washed thoroughly in the tub and scrubbed with ajax and a toothbrush.
Step 2) Both pieces were dried and sprayed with SEM "XXX Adhesion promoter"
Step 3) Both pieces were then painted with 2 different paints, one which is a "high temperature" engine paint, one is off the shelf regular spray paint.
Step 4) I let 6 hours pass to then solder a piece of wire to them with my large soldering torch.
Step 5) I used quite a bit of solder, and connected a piece of large wire (like 16 gauge) to it in 2 places. I did this by setting the painted side of the board down against a note-pad.
As you can see where i pressed against the white board it came off where it got really hot and grabbed itself onto the paper note pad. To prevent this from happening i then held the copper board with my hand and hit the same areas again with the soldering torch where there was already solder.
I soldered it as long as I could and just kept moving the solder around until the board was too hot to hold, and I had to sit it down. I then had to test how the paint was going to react so I wrapped my finger in my t-shirt (to protect myself from the heat) and gently tried to rub the paint off of the white one, and also the green one while they were hot.
The white paint would smear a little if I rubbed it hard, and the green paint really wouldn't
Just to let you know, the little "chip" marks were where I scratched the paint away with my fingertip. Both paints did this pretty much the same, even where it was cool and hadn't been soldered. I think this is because it just wasn't cured fully yet. I will let you know in another 2 days, because I really like to let paint sit for 2 full days to cure before I do any handling of it. This test was however supposed to be extreme.
The test was to simulate abusive soldering with a lot of solder and a lot more heat that I'd actually use to solder superflux.
I used a 25 watt gun, and held it as long as I could before my fingers started to hurt.
Any comments would be appreciated, this was done so that I can find a way to paint the boards so you don't see that ugly green "circuit board" color through the clear lenses of my headlights.
I am worried about reliability of the paint finish over time due to the exposure of soldering.