A note on conformal coating

In 1992 I was in high school going to a magnet school half-time for electronics. During the school year we had a regional electronics competition across the valley with all the school electronics programs in area. I don’t remember every bit of the competition; but as you can imagine there was theory, circuit analysis, math, troubleshooting and a practical soldering test. I somehow pulled off first place.. but not without having to pull off a soldering feat! Someone must have donated old through-hole aerospace related PCBs. There was a huge box of PCBs and they all had one ugly thing in common: Every single one had a thick layer of conformal coating! I’m guessing they came from Boeing. I was lucky; I’d run into these before or I’d likely not have won the competition. But I’ll get to that… Conformal coating comes in five (some claim six) types: Silicone, Epoxy, Acrylic, Polyurethane, and I’ll roll it up in “others”. They each have their application depending on your needs.. dielectric strength, flexibility, moisture resistance, etc. I typically use Silicone because it is flexible, and has good moisture resistance. The rest of this conversation is probably best viewed in video; so with that…

warning: this video drags on a little, 9 minutes could have easily been 4. I’m still not great at the whole video thing and I decided just to do this in one take.

Back to high-school days competition; the challenge was simple. Remove a two components and replace with new parts. I had gotten lucky that they had used acrylic coating and I chipped/scraped away most of the conformal coating without much damage or scaring. Everyone else just went and burnt through the coating to de-solder their targets… well as you can imagine it turned into a mess. Mine wasn’t anything I’d nail on a wall but apparently it was enough to be “award winning” šŸ™‚

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