eSIM Cards

Embedded SIM Card Specifications

The traditional plastic-backed SIM originated from the user equipment (UE) usage for telecommunication where customers needed to exchange SIMs easily as the devices were not bound to a particular SIM. Starting from 2016 on, the embedded-SIM (eSIM) or embedded Universal Integrated Circuit Card (eUICC) gained interest for developers due to the smaller footprint and deeper integration possibilities.

Especially in custom embedded Machine-to-Machine (M2M) and IoT hardware application cases, the eSIM offers unique advantages compared to the traditional FlexSIM. In purpose build IoT devices, there is no need for regular manual SIM Card swaps. Key factors like ruggedness, security and space constrains have high priority. For these special needs, the 1NCE eSIM Cards provide the ideal solution. This section covers the 1NCE eSIM Card product with its standardized form factor, technology specifications and outline recommended application cases.


1NCE FlexSIM compared to a 1NCE eSIM MFF2 Integrated Circuit.

eSIM Form Factor

As the eSIM evolved from the traditional FlexSIM, it shares the same technological functionality but just in a smaller physical packaged form factor. The eSIM format is commonly designated as MFF2. The 1NCE eSIM conforms to this MFF2 footprint in a Quad-Flat No-Leads 8 (QFN8) Integrated Circuit (IC) package. The MFF2 package is specified in ETSI 102 671.

The QFN8 eSIM package is not mounted inside a socketed adapter like the FlexSIM, it is designed to be directly soldered to the Printed Circuit Board (PCB) of a device. QFN8 is a often used footprint in electronic devices. Thus, it can be easily integrated into automated assembly production lines of IoT enabled devices. The specifications of the form factor are shown in the figure below.


1NCE MFF2 eSIM Form Factor Dimensions

Embedded-SIMs share the same basic pinout as FlexSIMs but in a different form factor shown in the figure above. The following table references the pin assignments and lists their respective functional pinout.

Contact PinSpec. Description1NCE eSIM Pinout
Supply Voltage
Reset Pin
Clock Signal
C4 and C8Optional
USB interface according to ETSI TS 102 600
Ground Connection
Programming Voltage
Input Output Data

Shipping & Assembly Packaging

When ordering 1NCE eSIMs, the QFN8 ICs are packaged in a standardized tape reel of 100, 500 and 3000 eSIMs. These tape reels can be directly used in an automated production assembly line.

1NCE eSIMs are packaged in 12mm wide tape, which is 1.2mm thick and covered with a plastic film to keep the eSIM ICs in place until production. The packing process and materials meet requirements defined in JEDEC J-STD-033 with ESD precautions and proper handling procedures. The tape is provided on 7inch (178mm) and 13inch (330mm) reels. For lots of 100 or 500 eSIMs, 7inch reels are used and for 3000 eSIMs the 13inch reels are used.


Specifications of the eSIM tape and reels used for packaging.

Each reel is vacuum packaged separately with a humidity indicator card, desiccant and a barcode label in a reel cardboard box. The barcode label shows the first and last eSIM ICCID of the specific reel. eSIMs are produced in sequence in ascending order where smallest ICCID is produced first and is at the end of the tape in middle of the reel. The user direction of unreeling is according to EIA-481 standard.


1NCE eSIM packaging reel and example barcode showing the first an last ICCID of the reel.

eSIM ICCID Identification

Each eSIM Card is uniquely identified by the ICCID. Same as for the FlexSIMs, the eSIMs are identified throughout the 1NCE ecosystem with the ICCID to mark each unique eSIM. The ICCID can be read by the hardware modem using an AT-Command or manufacturer specific request. For easier physical identification, each 1NCE eSIM has the ICCID of the particular SIM etched into the QFN8 package IC.

eSIM Specifications

SIM Cards for mobile network applications follow strict standards for the physical form factor as well as the technology and interfaces. 1NCE FlexSIM Cards comply with these technical standard specifications. Besides the key standard compliances, SIM Cards are validated for specific environmental ranges in which they need to be operated in. The table below shows the most important 1NCE eSIM Card specifications that are relevant for the deployment of the 1NCE eSIM. Furthermore, references to the key standard compliances for the SIM interfaces are referenced.

Parameter 1NCE eSIM
Form Factor (FF) MFF2, QFN8 (IC Package)
Supported Radio Access Technologies (RAT) 2G, 3G, 4G, CAT-M1, NB-IoT
Environmental Temperature -40°C to +105°C
Operating Voltages Class A, B and C (1.8V –5.0V ±10%)
Data Retention Period min. 10 years
Read/Write Cycles min. 500 000 cycles
Key Standard Compliances 3GPP TR 31.919
ETSI TS 101 220
ETSI TS 102 221
3GPP TS 31.101
3GPP TS 31.111
3GPP TR 31.900

Application Cases eSIM

Embedded-SIMs reduce the footprint of the SIM integration and also provide a more rugged and robust connection. In general, the eSIM form factor is more optimized for typical IoT device environments where factors like heavy vibration, higher temperature ranges but also increased security play a key role. 1NCE recommends the integration of eSIMs in custom developed IoT devices and use cases where extraordinary environmental robustness is needed.
As the eSIM is surface mounted to the PCB of a device, it provides higher security against end-user tampering as the SIM Card can not be easily removed. For prototyping and designing custom IoT devices, special QFN8 adapters are available to adapt an eSIM to the FlexSIM footprint.

For any open questions about the detailed 1NCE FlexSIM Card product or more extensive help in selecting the right SIM for the specific application case, feel free to contact us (1NCE Contact).