Samsung Fold4 mic replacement question

Thank you for your answer, Adam! What should I do in a situation where I can't find these particular microphones? I can find them in other countries, but at ridiculously high prices (around $8 each + shipping $10-20), and they aren't even available from the local MobileSentrix. Even if I search for "Samsung microphone" on their website, it only shows microphones for a very limited number of models. That's actually what made me think that Samsung microphones might be compatible as long as the pinout matches.

What do professional repair technicians usually do when the required part isn't available locally?

When a specific micro-component like a digital MEMS microphone isn't available through local suppliers like MobileSentrix, professional repair technicians usually bypass searching for individual loose parts and pivot to a few proven industry workarounds. Shops that do high-volume micro-soldering rarely buy individual $8 repair components. Instead, they buy strips or full reels of 50 to 100 universal MEMS components from commercial electronics distributors (like DigiKey or Mouser) or direct overseas supply brokers. When bought in volume, these micro-components cost pennies per unit.

@neross pin configurations (typically 4-pin, 5-pin, or 6-pin land grid arrays).If a microphone from a widely available model like a Galaxy S20 or S21 shares the exact physical layout and operates under the standard 1.8V digital standard, it can successfully be swapped onto your Fold4 board.

Update. I replaced both microphones. One was extremely difficult to desolder, so I had to take it apart piece by piece. It was rusty inside.

Unfortunately this did not solve the problem. The sound came back but the noise did not disappear completely. It became quieter and intermittent.

Also somehow, the sound from these upper microphones when recording video is being routed to the opposite speaker - the one near the bottom microphone. So the stereo effect is messed up.

I guess the problem is related to other components on the motherboard. This board will be installed in a phone that has never been exposed to water and where all other components are known to be working properly. So the problem cannot be anywhere else but the mainboard.

For now, the solution I see for myself is to leave the board without the upper microphones. There will be no stereo recording in video but at least there will be no noise.

If you have any advice or suspect a specific component on the board, please let me know. Thank you.

@neross Leaving the upper microphones off the mainboard is a perfectly viable, low-risk fallback option that protects your clean chassis from experiencing background noise, though it will limit you to mono audio capture.Given that the original microphone was severely corroded and required aggressive, piece-by-piece physical teardown to remove, the remaining symptoms point to structural and electronic side effects localized on the mainboard.Why the Noise and Stereo Swap Are OccurringThe Inverted Stereo Routing: In modern smartphones like the Samsung Galaxy Z Fold 4, microphones are often configured as a differential pair or multi-mic array linked to a shared Audio Codec IC or PMIC. If the traces under the destroyed microphone pad were bridged during the difficult extraction, or if the new microphones installed have a slight variance in technical specifications (such as a different digital land grid array mapping or inverted clock/data lines), the phase matrix of the audio chip gets thrown off. The software att