2002-0059 Fujitsu Limited

Tokyo, March 13, 2002 -- Fujitsu Limited today announced the development of an ultra-high density, multi-chip package (MCP*1) that can support up to eight chips (see Figure 1). This achievement was made possible by the company's advances in thin chip processing*2 and MCP technology*3.

As mobile phones, digital audio/video equipment and integrated circuit (IC) cards grow more sophisticated, there is corresponding demand for smaller, thinner, more densely integrated and higher-capacity LSIs, such as chip-scale packages (CSPs*4) and MCPs.

Typically, the mounted surface area on a circuit board allows for 1.2-1.6 mm thick packages. The thickness allowed for one chip depends on the number of stacked chips per package. Thus, three-stacked packages require a 0.15 mm thickness per chip, while four stack must be 0.1 mm, and five or more, 0.08 mm or less. To create chips less than 0.1 mm thick, however, requires a chemical process beyond conventional polishing techniques, entailing longer chip processing times, higher equipment costs and problems associated with environmental emissions.

The new MCP is the result of improvements in both ultra-thin wafer processing (announced December 2001) and advanced multiple chip packaging technology. This slimming process enables the production of wafers as thin as 0.025 mm without the use of chemicals, thereby resulting in reduced manufacturing cycles, equipment costs and impact on the environment. While Fujitsu's existing MCPs could house a maximum of four chips within a 1.6 mm package height, the new wafer-slimming process alone makes it possible to produce MCPs with up to six-stacked chips. Combined with the company's advanced new packaging technology, a maximum of eight chips (package height of 2.0 mm) can now be mounted onto a single MCP. Another benefit of these technological advances is that IC cards and compact hard disk drives, which previously could hold only two-chip packages, are now able to support three-chip combinations (LGA*5 package height of 0.5 mm).

The new packaging technology is an ideal mounting technique for ultra-high density packages. Until now, each circuit board was limited in the size of chip that could be mounted onto it, and complications arose in configuring outside electrical connections when layering chips of identical sizes, as electrical connectors could not be stacked to reach upper layers. With this advanced packaging technique, chips are attached to one or both sides of the circuit board while using lead-free solder balls to bond packages to the board. This makes it possible to stack a number of chips of all shapes and sizes, including those of the same size.

Glossary

*1: Multi-chip package (MCP):

Multiple chips packaged in a single unit

*2: Thin wafer processing:

A special wafer-support technology that permits chips to be polished down to a thickness of only 0.025 mm.

*3: Multi-stacked package technology:

Stacking boards mounted with chips using lead-free solder balls, functionally equivalent to a single package.

*4: Chip-scale package (CSP):

A package with nearly the same width and height as the chip it encloses.

*5: Land grid array (LGA):

A type of plastic surface-mount package.

Trademarks

All product names and other proper names mentioned herein are the trademarks or registered trademarks of their respective companies.

About Fujitsu
Fujitsu is a leading provider of Internet-focused information technology solutions for the global marketplace. Its pace-setting technologies, best-in-class computing and telecommunications platforms, and worldwide corps of systems and services experts make it uniquely positioned to unleash the infinite possibilities of the Internet to help its customers succeed. Headquartered in Tokyo, Fujitsu Limited (TSE:6702) reported consolidated revenues of 5.48 trillion yen for the fiscal year ended March 31, 2001. Internet: http://www.fujitsu.com/


Figure 1. Cross section of eight-stacked MCP
[Click to enlarge]

[Press Contacts] Chiaki Kuwahara, Nancy Ikehara Fujitsu Limited, Public Relations Tel: +81-3-3215-5259 (Tokyo) Fax: +81-3-3216-9365 Press Inquiries

[Customer Contact] Fujitsu Limited Electronic Devices Group Advanced Packaging Technology R&D Dept., II LSI Packaging Division Tel: +81-42-532-2164 E-mail: edevice@fujitsu.com

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