I'm looking for a way to secure a pcb I will be making for a cherry mx (homemade) keyboard to a case which I'll also be making. Obviously, I don't want the pcb to move. I could use standoffs/screws, but wouldn't the added height between the pcb and case cause the pcb to flex when keys are pressed? Glue/tape seems mega sketch and may mess with conductivity. How is this done on normal (production) keyboards? Advice is much appreciated.
Answer
In a previous company, we used VHB 4905 tape by 3M. You can use it to secure a PCB to an enclosure, and then use it to seal the enclosure, too :)
It has a body thickness of 20mil, so it's pretty compliant. It's non-conductive (10^16 Ohms/square), and has a breakdown voltage of 630V per mil. We never saw any issues with using it to stick PCB's to aluminum housings.
If your PCB has RF components, the dielectric constant of any material may detune your rf circuitry...
The datasheet for the entire line of VHB tapes is here. Page 7 shows the electrical characteristics. It's not cheap, but you can get a short roll on Amazon for about $17.
As an aside, once I took some home and taped a pewter key hook to my wall. A year layer, when I tried to remove it, the paint and sheetrock tore away before the VHB! Nothing like a little quick spackling as you leave :)
Good luck :)
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