Ok I managed to apply the UV solder mask today and it seems like it worked quite smoothly. I used the tip of a small sewing needle to spread it over the trace and then held the UV light on it for 10 seconds to play it safe. I used transparent UV solder mask so you can still see the trace but its a bit more murky/cloudy when you see it. I used the tip of an exacto knife to put little scratches on the UV solder mask to test its thickness by feel and test its durability a bit to scratching. And ensure it was fully cured. It was very hard and durable and seems to have gone on fairly thin. The question is, is it too thick/proud of the surface for the soldering on of the chip over it? This is the million dollar question. Because if the mask lifts the chip up off the PCB even a tiny bit then the soldering may not reach between pads on the IC and pads on the PCB, failing to bridge the distance. That is my main concern. If I have any issues with that, I will have to reroute this trace to go around everything rather than on the shortest path like it is now. The shortest path leads it under the IC and led me to have to mask it. Extra steps like this are a bit annoying. I kind of wish I just routed it around everything out of the way more. Then I would not need to UV solder mask at all. Perhaps in a future board iteration I will do this improvement but we'll see. For now I made several boards and want to stick to them since it would be more work to remake them all.











