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by simonrobb
1333 days ago
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That's correct in my experience. Galvanic corrosion was never a problem for the capacitive sensors I developed a few years back (unlike the resistive sensors linked by the parent). However you typically want them more rugged than a bare PCB for industrial settings and since the capacitive field can pass through plastic I had them in a plastic housing filled with resin. Perfectly isolated from the outside environment and hard as a rock. Here's a prototype: https://imgur.com/9yO28CY |
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What I don't see anyone talking about is the impact of dielectric moisture absorption[1], which is typically around 0.3-0.5% over 24 hours exposure for cheaper FR-4 on the market, let alone how this product intends to maintain sensor calibration over time.
I'd expect to see external corrosion impact at the solder joints first, especially around the battery terminals, but corrosion creep may happen alot sooner than that: vias in the b-parasite prototype are clearly tented[2], but that masking is superficial and won't protect against hygroscopic exposure from the inside; being open source certainly doesn't preclude hobbyists from making even worse material decisions either.
[1] https://www.ipc.org/sites/default/files/test_methods_docs/2....
[2] https://github.com/rbaron/b-parasite/blob/main/img/resized/i...