What is MFF2
Quick definition
MFF2 (Machine-to-Machine Form Factor 2) is the solderable SIM: a 6x5 mm chip mounted directly on the PCB, no tray or socket. It is the de-facto standard in industrial IoT, automotive, and any device facing vibration, humidity, or extreme temperatures.
Why solder it
A SIM tray has screws, exposed contacts, and failure points. Soldering removes theft, vandalism, dirty contacts, thermal cycling, and vibration. It also saves 2-3 mm of height, useful on compact boards.
Risks and mitigation
The big risk is that the carrier whose profile you soldered shuts down or raises prices. That is why MFF2 today is almost always sold as eUICC: the chip is solderable but the carrier profile can change OTA.
FAQ
Can I change carrier after soldering an MFF2?+
Only if the MFF2 is eUICC. If it is a classic MFF2 with a single profile burned in, you are stuck with that carrier for the lifetime of the chip.
What temperature can MFF2 take?+
Industrial MFF2 chips handle -40 to +105 degC, more than any removable SIM. That is one of the reasons to pick the form factor.
Related terms
What is eUICC
An eUICC (embedded Universal Integrated Circuit Card) is a programmable SIM chip that can hold several carrier profiles and switch between them over the air. It is the GSMA standard underpinning every modern eSIM, in phones, vehicles, and IoT devices.
What is iSIM
iSIM (integrated SIM) is a SIM whose silicon lives inside the modem or SoC, not as a separate chip. It shares the same eUICC logic and the same GSMA standards, but takes zero extra board space and trims bill of materials.
What is IoT eSIM
IoT eSIM is the eUICC SIM designed for headless devices. It inherits smartphone eSIM programmability but uses a Pull provisioning flow (SGP.32) where the device asks the server for a profile, without scanning a QR code or entering an activation code.