Package-on-Package Memory System Solutions for Mobile Applications

STMicroelectronics has announced the availability of memory solutions using Package-on-Package (PoP) technology - a packaging development that makes significant board space savings for the high-density memory and complex processor combinations typically employed in high-end handsets.

The PoP structure allows two BGA (Ball Grid Array) packages to be stacked on top of each other: the Bottom PoP package features the normal array of metallic balls, or bumps, on the underside of the package, but also has an array of footprints (lands) on the top surface that are designed to receive a mating Top BGA package. Industry standards are being defined by the JEDEC association.

The technique enables devices to be assembled in a vertical stack consisting of a discrete logic device, such as a baseband or application processor, with a memory BGA package soldered on top. Standardized ballouts route signals between them. As well as saving space in the application, PoP offers great flexibility in component combinations and design,

In addition, manufacturers are able to source and test the typically complex memory system and logic device separately, simplifying assembly flow for high-performance mobile multimedia products. ST's PoP memory solutions will complement its existing MCP (Multi-Chip Package) portfolio - in which multiple chips are mounted in a single package to minimize the space requirement, increase memory density and provide combinations of different memory types - so improving choice for system designers.

"The use of PoP technology is gaining momentum with our partners," said William Vespi, Strategic Marketing, NOR Wireless Division, STMicroelectronics. "PoP technology perfectly matches demands for both flexibility and board miniaturization."

The first samples available for the market are 12x12mm (128 balls) and 14x14mm (152 balls) package sizes, with 0.65mm ball pitch. Both split bus and shared bus architectures are supported. A range of components can be selected for the PoP configuration, including NOR Flash, NAND Flash, PSRAM, LPSDRAM and LPDDRAM."

Posted to the site on 14th September 2006