Overview

This chapter will describe processes that are being used today and others that can be valuable in the future for assembling microelectromechanical systems (MEMS) and micro-optoelectromechanical systems (MOEMS) devices into packages. Package additive and sealing processes, which are a unique aspect of MEMS packaging not found in other technologies, are also covered. Many processes are standard assembly methods that are used for electronic devices and that is the intention. We should endeavor to take advantage of the well-established existing packaging infrastructure whenever possible. There is a high cost penalty for ignoring established methods and employing nonstandard equipment if it is not really necessary. Process modification is a different issue. Changing the sequence or adding steps that can be handled by existing equipment and process methods is quite acceptable. Some high-volume MEMS packaging has been able to tap into the existing methods to use packaging lines, even though the package designs and materials are new and different. But there will be some device packages that require different methods and equipment to accommodate the special needs of MEMS devices. MEMS ink-jet chip packaging is a good example of a specialized design and process. The flex-based package-circuits are unique in the world of packaging, although existing materials, processes, and equipment have been used with some modification.

MEMS inertial sensors were first packaged in fully hermetic ceramic enclosures but the cost of the package could exceed that of the device. Device fabricators were forced to lower margins and sometimes sell at...