Connector suggestion

[lichurbagan]

For a removable expansion module, would you recommend a edgeboard connector or a mezzanine board-to-board connector? I'm interested in durability and assembly cost. I came across these edgeboard connectors Are there drawbacks I should know about?

[tooki]

You’re going to need to tell us more about your requirements, including (but not limited to) things like:
-operating environment (vibration, temperature cycling, etc)
-signal type (high speed?)
-number of pins
-size of the boards
-number of mating cycles

[lichurbagan]

Thanks. I'm designing a PCB for a simple ESP8266-based Internet clock. The main board will contain the ESP8266 and power circuitry. A small front-panel board will hold the 0.96" I²C OLED display and the push button. I'd like the front-panel board to be removable for easier assembly and servicing. The clock will be used indoors on a desk. So there won't be much vibration. The board will only be connected and disconnected occasionally.
Here is a picture of my current prototype.

[tooki]

Card-edge connectors will be far too big for that application, then! Mezzanine connectors are fundamentally small, fragile connectors intended for high-speed signals. I wouldn’t use those, either.

You have many options, but there is likely little that would be cheaper than using bog-standard 0.1” (2.54mm) headers. I would probably put a through-hole male header on the main PCB and a surface-mount vertical header on the back of the display PCB.

If the both PCBs are firmly and accurately held by the enclosure, and you wanted to go super fancy, you could even use pogo pins or other spring contacts on the main PCB to contact pads on the display PCB.

P.S. The ESP8266 is super ancient. Why not use the modern successor, the ESP32-C3?

[lichurbagan]

Card-edge connectors will be far too big for that application, then! Mezzanine connectors are fundamentally small, fragile connectors intended for high-speed signals. I wouldn’t use those, either.

You have many options, but there is likely little that would be cheaper than using bog-standard 0.1” (2.54mm) headers. I would probably put a through-hole male header on the main PCB and a surface-mount vertical header on the back of the display PCB.

If the both PCBs are firmly and accurately held by the enclosure, and you wanted to go super fancy, you could even use pogo pins or other spring contacts on the main PCB to contact pads on the display PCB.

P.S. The ESP8266 is super ancient. Why not use the modern successor, the ESP32-C3?

Thanks for all suggestions, sir. Actually the prototype  is quite old. But since I still have the ESP8266, I saw no problem in keeping on using that.