Memory // Innovations

The Mobile Package Just Got Smaller

By Jim Cooke - 2015-03-04

Mobility is now becoming pervasive. As the global population strives to achieve constant connectivity, the trend that began with cellular phones and was quickly replicated across consumer electronics with e-readers and tablets is now being seen as a requirement in many other segments of the market, from industrial to medical.

This demand results in the requirement for ever-smaller printed circuit boards (PCBs), and one of the most effective ways to achieve this is to stack two packages on top of each other, known as package-on-package (PoP). The two main benefits of PoP are board space savings and minimizing track length between different interoperating parts, such as a CPU and memory. This yields better electrical performance of devices, since shorter routing of interconnections between circuits yields faster signal propagation and reduced noise and cross-talk. Based on these advantages more and more companies are looking to design utilizing PoP, most commonly placing the CPU on the PCB and stacking the memory package on top.

The i.MX 6Dual/6Quad processors feature Freescale’s advanced implementation of the quad ARM® Cortex®-A9 core, which operates at speeds up to 1 GHz. They include 2D and 3D graphics processors, 3D 1080p video processing, and integrated power management. Since the launch of the i.MX 6 series, customers have based designs ranging from automotive infotainment systems to industrial, consumer, and medical devices on these processors. Both parts are currently available in a 21mm x 21mm, 0.8mm pitch FCPBGA package; however, Freescale has increasingly been asked by customers to enable smaller designs with these processors. Based on this customer demand, the i.MX 6Dual/6Quad processors will be available in a smaller 12mm x 12mm, 0.4mm pitch FCPBGA PoP, with the upper package being a 4Gb Mobile LPDDR2 memory package from Micron. Both the top and bottom of the package meet the JEDEC-standard design guideline, ensuring ease of design and layout for customers.

PoP, similar to any technology, has advantages but can also present design challenges. Two challenges that may occur with any PoP are soldering between the packages and thermal dissipation. Both of these challenges can be overcome if the two packages are designed and tested in a stacked PoP implementation. Knowing that reliable PoP development requires close collaboration with the memory vendor, Freescale chose to partner with Micron for their i.MX PoP offering. Together, we can carefully engineer the packages and review the thermal profiles to ensure maximum compatibility. Micron’s PoP User Guide (CSN 34) provides a wealth of technical information.

Download the PoP user guide

Micron is a major player with LPDRAM and PoP packages in the mobile/wireless space and is now a market leader in supporting LPDDR in the non-wireless space.   We worked closely with Freescale in developing an automotive temperature grade 216-ball 8Gb (dual-die) x64 LPDDR2 PoP for use on the i.MX 6Dual and 6Quad application processors.  This PoP device provides simpler routing to a system and provides board space savings to customers.  The LPDDR2 has been tested and guaranteed to function up to a max temp of 105°C  (typical max temp = 85°C). The memory package also includes on-die temperature sensors that can be used by software to throttle the application processor down if the temperature gets too hot and increase the refresh rate of the DRAM.

Working with Micron has enabled Freescale to offer customers a reliable, long-term PoP solution. However, they realize that many customers looking to capitalize on the advantages of PoP have little experience with the technology. To provide not only an evaluation board, but also design services and expertise in PoP designs, Freescale has worked with two partners that have extensive experience with PoP designs across many industries: TechNexion and Mistral Solutions.

Mistral Solutions has recently launched the VISE board, which runs on the 800 MHz quad/dual core i.MX6 PoP.  The VISE board is based on a dual-board architecture, consisting of a core module and a carrier module comprised of display, audio, gigabit Ethernet, and other peripheral Interfaces. The VISE board is an ideal platform to kick-start design and development of devices, from wearables to security cameras. The VISE board is available via Arrow Electronics at For more information on Mistral and the VISE board, go to

The Pico -6QPoP board from TechNexion is a small form factor (35mm x 40mm) system-on-module that connects to a breakout board that contains sensors and additional interfaces that enable easy access to peripherals. The Pico board will be available in 2Q15 from TechNexion and through major distributors.

Both boards will support both Yocto Linux and Android Kitkat, ensuring both customer choice and fast time to market for software, as well as hardware development.

If you’re looking to design a product where small size is a premium, take a look at Freescale’s PoP solution that is coming soon; it might well be the package you are looking for.

Jim Cooke

Jim Cooke