Fujitsu Semiconductor Develops Ultra-Compact Packaging for 1-Mbit Serial FRAM

Among the industry’s smallest, enables smaller and slimmer wearable devices using non-volatile, low-power memory

Singapore, July 8, 2015 –Fujitsu Semiconductor Pacific Asia Ltd. today announced the development and availability of its 1-Mbit FRAM (*1) product, MB85RS1MT, in an 8-pin wafer level chip scale package (WL-CSP). This new package occupies only 23% of the mounted surface area of the existing 8-pin small-outline package (SOP), and is roughly one-fifth as thick, making a 1Mbit FRAM with a serial peripheral interface (SPI *2) available in the industry’s smallest size class as FRAM products.

WL-CSP FRAM is the ideal memory for wearable devices. In addition to contributing to smaller overall size for the application itself, FRAM minimizes power consumption during write operations, contributing to longer battery life.

The wearable market, which is attracting considerable attention today, is expanding dramatically. While it includes such diverse categories as accessories, such as eyeglasses and head-mounted displays, medical devices, such as hearing aids and pulse meters, and activity trackers that record calories burnt and running data, one feature many of them have in common is the need to continuously log data in real time.

Figure 1: Comparison of the SOP and WL-CSP packages.

While typical non-volatile memory technologies such as EEPROM and flash memory only guarantee data integrity minimum 1 million write cycles, Fujitsu’s FRAM technology guarantees vastly more: minimum 10 trillion read/write cycles, making it ideal for storing real-time log data.

Figure 2: Comparison of mounted surface area

To make even better use of this feature, Fujitsu Semiconductor has now extended its MB85RS1MT line of 1-Mbit FRAM devices with a new WL-CSP package (Figure 1).

The MB85RS1MT is already available in the industry-standard SOP package, but the WL-CSP has very small dimensions of 3.09 × 2.28 × 0.33 mm. The mounted surface area of WL-CSP is only 23% that of the SOP, or a 77% reduction in area (Figure 2). Furthermore, with a thickness of only 0.33 mm, or roughly half that of a credit card, the mounted volume is 95% less than that of the SOP (Figures 3, 4).

One of the benefits of FRAM is its low-power operation. Compared to the commonly used EEPROM non-volatile memory, write operations are faster as well, so there is much less power consumption amount during write operations (Figure 5). For this reason, using this FRAM in wearable devices that generate frequent write data for real-time logging brings the benefits of both better battery life and smaller size.

Figure 5: Comparison of power consumption amount during write operations

The availability of the MB85RS1MT in the WL-CSP package will help wearable device manufacturers produce smaller, slimmer, and more functional products, and greatly extend battery life. Fujitsu Semiconductor as always will continue to provide products and solutions that raise the value and utility of its customers’ applications.

Key Specifications

Part Number: MB85RS1MT

Density (configuration): 1 Mbit (128K × 8 bits)

Interface: serial peripheral interface (SPI)

Operating voltage: 1.8–3.6 V

Guaranteed read/write cycles: 10 trillion

Data retention: 10 years (at +85°C)

Package: 8-pin WL-CSP, 8-pin SOP

Glossary and Notes

FRAM

Ferroelectric random-access memory. A type of memory that uses a ferroelectric film as capacitors that store data. Retains contents even when power is removed. Combines benefits of both ROM and RAM, with fast write speed, low-power consumption, and high read/write cycle endurance. Also known as FeRAM. Produced by Fujitsu Semiconductor since 1999.