Stacked memory

A new type of stacked memory product involves the modification of Thin Small Outline Packages to permit them to be stacked and mounted using Ball Grid Array attachment technology.

Irvine Sensors is developing a new type of stacked memoryproduct that involves the modification of Thin Small Outline Packages(TSOPs) to permit them to be stacked and mounted using Ball Grid Array (BGA) attachment technology, with a height nearly half that of a comparable stack of standard BGA packages.

Chip packages with BGA attachments generally use much less area and save valuable mounting space on circuit boards as compared to TSOPs. Because of this advantage, semiconductor manufacturers are increasingly offering integrated circuits (ICs) in BGA packages. However, not all ICs are expected to be available in BGA packages, at least not initially.

Furthermore, a stack of unmodified BGA packages can exceed the physical height requirements of some applications. The new Irvine Sensors stacked memory products are being developed to address both of these issues.

The first products being developed consist of stacks of up to four Micron 512 Mb SDRAM Double Data Rate (DDR) 333 MHz parts. A two-chip-high version of this stack is expected to be only 1.7 mm high, compared to a height of 3.2 mm for Irvine Sensors’ stack of two comparable standard BGA parts.

A four-chip-high version is expected to be only 3 mm in height. Future products are also expected to include stacked SDRAM and DDR memory chips not presently available in BGA packages.

Irvine Sensors projects production availability of the first stacked low-profile BGA parts in the July – September quarter.

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