There are many references by MEMS experts as to the high percentage of the product cost attributed to the "Back end" (i.e., package and test). This percentage has been cited as high as 70% of the total cost. Packaging has not until recently received the research and development attention it deserves as a key enabler for

microsystems commercialization. Packaging has often been referred to as the "Achilles Heel of MEMS Manufacturing" and a key "Bottleneck" in the process of MEMS commercialization.

A significant amount of attention is now being directed at packaging concerns. Packaging was an afterthought for most MEMS designers and manufacturers only a few years ago. Now it is part of the initial design process as mentioned by many notables such as Dr. Steven Senturia (see the Design, Simulation, and Modeling chapter for further insight). It is this second question that will dominate packaging and assembly over the next 5 years in order to make the majority of MEMS devices cost-effective and more ubiquitous in the marketplace. Therefore, a chapter in this MST Roadmap has been dedicated to the challenges of packaging.

Assembly of MEMS devices utilizes many engineering and design tools and supporting infrastructure for microsystems. There is a trend for MEMS specific packaging and assembly tools from EVG, Karl Suss, MA3 Solutions and many others, although Cost of Ownership in relation to the often relative small production volumes can be a problem. But, to date, many MEMS devices are developed using equipment not specifically MEMSoriented, but more likely standard semiconductor industry equipment that has been modified somewhat.

This chapter focuses on the recent developments in MEMS packaging, as well as discusses the future of this subindustry. One of the more promising approaches to MEMS packaging appears to be the "Supply Chain Method" and this process is discussed.

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