I very highly doubt it's a 6-layer board. With that number of components, you could easily lay it out on 2 layers. More likely there's just three fiberglass layers together for thickness.
I'd wager a guess that that microprocessor is a mask rom 8051 for that price. The metallization layers in the middle usually mean mask ROM, don't ask me why but I've seen it on many decapped chips. I like the videos! You get one of my rare thumbs up for actually making something interesting.
Fiberglass layers does not correspond to copper layers, you can have 2mm pcb with 2 copper layers or you can have 0.6mm pcb with 2 copper layers. 2mm pcb has more fiberglass layers for sure. I'd like to see more such videos, teardowns are always exciting.
Perhaps a scope on the humidity capacitor alone and see what it does?, good fun though!, i would guess the microprocessor so it can talk to the arduino with simpler layout, rather than building something to interface a tiny capacitance change to a digital input and have a way to calibrate it, this is already done, still amazing for a couple of dollars though
What acid did you use? I could not understand that. I doubt that it was a 6 layer board. You delaminated the base material which most likely was built up of three layers of glass fiber.
I'm kind of meah... Either way. But I would point out that thumbs down do help your channel as much as the thumbs up do as far as RU-vid goes. So it is kind of a good voting system.
***** yeah the tax rebate on that $3.45 has him living well! i dont think he breaks much above $10 per video, i suppose he makes that back at some point in revenue from views
jusb1066 Actually I worked out he earned approx $6000 in the last year purely via click through. High quality niche views such as this subject doubles his CT1K. He also has a business email I presume for sponsorship. It's a quality channel
RU-vid cpm rates are not even close to being that high....you might notice many tech channels adopting patreon begging campaigns just to make ends meet
***** and the patreon campaigns every year from the same youtubers is annoying tbh...plus the begging for free products from viewers and sellers, i dont like that kind of channel