Small and sustainable: new eSIM form factors

Miniaturization is a huge imperative across connected devices. Indeed, it is one of the prime drivers of innovation in the field. The advantages that accrue from ever smaller devices are obvious. To name just one gain: lighter, more portable devices mean more applications, including across wearables, tracking devices, logistics, weather networks, and the like. 

To illustrate, nobody wants a giant fitness tracker in the swimming pool, or an unwieldy hearing aid. It just isn’t feasible. Smaller is better when it comes to connected devices.

But the shrinking real estate of the device itself comes at a cost. There already isn’t much space on most of them. Therefore,  stakeholders in connectivity welcomed the European Telecommunications Standards Institute’s (ETSI) recent standardization of two new embedded SIM (eSIM) module types, Machine Form Factor 3 (MFF3) and MFF4. These measure a mere 3×3 mm and 2×2 mm respectively.¹

These new form factors are a significant leap forward for eUICCs: the 2×2 mm MFF4 marks the very first time a fully standardized eSIM module can fit into such a small housing. This is in line with the rising demand for ultra-compact connected devices that are also power efficient.

Innovations within the semiconductor industry toward ever-smaller tech nodes have enabled the manufacturing of smartcard-grade secure elements in reduced die sizes. The new ETSI standards are matching up with the advances in semiconductor tech to make a new generation of high performance, ultra-small eUICCs possible.“By shrinking down to just 2×2 mm, the MFF4 gives device makers new freedom to innovate – whether it’s building smaller wearables or ultra-compact IoT sensors, or simply leaving more space for batteries and antennas,” noted Ralf Schedel, Head of Portfolio Management & Business Planning at G+D. More space for batteries and antennas of course means longer lives and better connectivity, all working together in slimmer, lighter devices.

Futureproofing is a strong term, but these new form factors do give players in the IoT and connected devices markets an advantage.

The current eSIM landscape

It is fair to say that eSIM technology is prevalent now across connected devices, delivering secure and flexible connectivity without the need for physical SIM cards. In the current scenario, many eSIM modules are based on the older MFF2 design. Measuring 5×6 mm, the older form factor is in wide use across IoT devices, automotive solutions, and industrial applications.

There are other packaging concepts. However, broadly scalable deployment remains an issue for them, at least at present. Among others:

Wafer Level Chip Scale Packages (WLCSP) offer a very small footprint. However, the lack of a standardized pinout means that each PCB requires adaptation to the specific chip. This introduces layers of complexity in manufacturing, as handling and soldering requirements needs to be adjusted. It also reduces supplier flexibility.   

Integrated SIM (iSIM) delivers compactness by placing the SIM functionality directly in the modem chipset. This ties the original equipment manufacturer (OEM) to the chipset vendor, however. Additionally, certification requirements of discreet security elements might be an issue for manufacturers.

The importance of the new form factors

The new form factors deliver other gains: let’s focus here on the smaller MFF4. “It combines the compactness of iSIM or WLCSP with the universality of standardized eSIM modules. It’s not only smaller and more sustainable, it is also fully compatible with the pin arrangement of MFF2, enabling manufacturers to adopt it without the need for full platform redesign,” noted Ralf Schedel, Head of Portfolio Management & Business Planning at Giesecke+Devrient. Among other things:

• MFF4 is the smallest standardized eSIM form factor currently available
• The material savings in producing a smaller form factor deliver a tangible and scalable benefit in terms of sustainability compared with larger modules more commonly in use today, which is attractive to manufacturer and user alike
• Chips with very large Non-Volatile Memory (NVM) might not fit in the MFF4 housing due to their die size, but with increasing chip density it is expected that such chips will also be able to fit into the smaller modules
• MFF4’s standardized layout renders it hardware-supplier-independent, and easy to adapt to existing manufacturing processes

As MFF4’s pin arrangement is identical with MFF2 – unlike WLCSP for example – it is easy to migrate from MFF2 to MFF4

OEMs can adopt these new form factors without having to redesign their existing products, while also using them as a platform for their new products. This adds measurable value in terms of product strategy and accelerates time-to-market.

Usable across industries

Given their size, the new form factors are opening a world of possibilities, including in:

Consumer electronics More space for batteries, antennas, and other entirely new features, which can be transformative for the design of mobile devices, laptops, and the like. 

Health technology and wearables From hearing aids and medical patches to fitness trackers and smartwatches, one requirement remains constant: compact design. 

Industrial IoT Smart meters, environmental sensors, and maintenance nodes in harsh environments need small, robust modules with long lifetimes.

Mobility and automotive The new form factors provide automotive and mobility OEMs with a reliable and standardized alternative for connected car modules and vehicle-to-everything (V2X) systems.

Logistics Asset trackers, parcel trackers and smart labels can all benefit from the MFF4’s small footprint to really minimize device size and lower power consumption, while maintaining secure global connectivity.

An eye to the future

MFF3 and MFF4 combine miniaturization, sustainability, and interoperability. This makes them viable and attractive alternatives to the larger MFF2 modules currently in use. 

The chip is where the full stack solution begins, of course. With a standardized, compact, and secure eSIM module such as the MFF4, ETSI has delivered a foundation for the next generation of connected devices. As miniaturization continues to be a dominant force driving the future of connected devices, the new form factors – especially the MFF4 – will influence developments across consumer electronics, mobility, and the IoT.

As a global SecurityTech leader, G+D combines decades of expertise in secure connectivity with a portfolio that spans eSIM solutions, device enablement, lifecycle management, and global IoT connectivity. We support manufacturers and service providers in building reliable, scalable, and future‑ready connected products.

G+D is well positioned to support device makers who are navigating this next chapter in innovation, in consumer electronics and the IoT.

Published: 30/04/2026