Subscriber Identity Module - Formats

Formats

SIM cards have been made smaller over the years; functionality is independent of format. Full-size SIMs were followed by mini-SIMs, micro-SIMs, and nano-SIMs. SIMs are also made to be embedded in devices.

The first to appear was the full-size or 1FF (1st form factor), the size of a credit card (85.60 mm × 53.98 mm × 0.76 mm). It was followed by a version of the same thickness but 25 mm long by 15 mm wide, with one of its corners truncated (chamfered) to prevent misinsertion. It is known as a mini-SIM or 2FF (2nd form factor). The next version was the micro-SIM or 3FF (3rd form factor), with dimensions of 15 mm × 12 mm.

The mini-SIM card has the same contact arrangement as the full-size SIM card and is normally supplied within a full-size card carrier, attached by a number of linking pieces. This arrangement (defined in ISO/IEC 7810 as ID-1/000) allows such a card to be used in a device requiring a full-size card, or in a device requiring a mini-SIM card after breaking the linking pieces.

The later 3FF card or micro-SIM cards have the same thickness and contact arrangements, but the length and width are further reduced as above.

In early 2012, the nano-SIM or 4FF (4th form factor) was introduced, which measures 12.3 × 8.8 × 0.67 mm and reduces the previous format to the contact area while maintaining the existing contact arrangements. A small rim of isolating material is left around the contact area to avoid short circuits with the socket. The 0.7 mm thickness of the nano-SIM is about 15 percent less than its predecessor. 4FF can be put into adapters for use with devices taking 2FF or 3FF SIMs.

SIMs for M2M applications are available in a surface mount SON-8 package which may be soldered directly onto a circuit board.

The micro-SIM was developed by the European Telecommunications Standards Institute (ETSI) along with SCP, 3GPP (UTRAN/GERAN), 3GPP2 (CDMA2000), ARIB, GSM Association (GSMA SCaG and GSMNA), GlobalPlatform, Liberty Alliance, and the Open Mobile Alliance (OMA) for the purpose of fitting into devices otherwise too small for a mini-SIM card.

The form factor was mentioned in the December 1998 3GPP SMG9 UMTS Working Party, which is the standards-setting body for GSM SIM cards, and the form factor was agreed upon in late 2003.

The micro-SIM was created for backward compatibility. The major issue with backward compatibility was the contact area of the chip. Retaining the same contact area allows the micro-SIM to be compatible with the prior, larger SIM readers through the use of plastic cutout surrounds. The SIM was also designed to run at the same speed (5 MHz) as the prior version. The same size and positions of pins resulted in numerous "How-to" tutorials and YouTube video with detailed instructions how to cut a mini-SIM card to micro-SIM size with a sharp knife or scissors. These tutorials became very popular among first owners of iPad 3G after its release on April 30, 2010, and iPhone 4 on June 24, 2010.

The chairman of EP SCP, Dr. Klaus Vedder, said

"With this decision, we can see that ETSI has responded to a market need from ETSI customers, but additionally there is a strong desire not to invalidate, overnight, the existing interface, nor reduce the performance of the cards. EP SCP expect to finalise the technical realisation for the third form factor at the next SCP plenary meeting, scheduled for February 2004."

The surface mount format provides the same electrical interface as the full size, 2FF and 3FF SIM cards, but is soldered to the circuit board as part of the manufacturing process. In M2M applications where there is no requirement to change the SIM card, this avoids the requirement for a connector, improving reliability and security.