Challenges and Solutions for Cost-effective RF-MEMS Packaging

Packaging poses a critical challenge for commercialization of MEMS (micro-electro-mechanical system) products. The packaging provides the critical structural and environmental protection necessary for fielding repeatable and reliable MEMS devices. For high volume markets such as mobile wireless terminals, where the technical benefits of RF-MEMS are highly attractive, the cost of effective packaging and assembly is a primary barrier to their adoption. RF-MEMS packaging is a nascent engineering field with widely varying approaches being explored to balance the broad range of technological and cost constraints. The cost of the packaging itself and all processing steps used to assemble the final product must be comparable to conventional packaging approaches used throughout the semiconductor industry. At the same time it must provide the necessary protection for the MEMS surfaces throughout the life of the product and not degrade the high RF performance provided by the MEMS. A key related aspect is additional functional integration enabled through MEMS that reduces the number of components required for a given application. In this paper, we describe the breadth of the RF-MEMS technologies and their associated packaging challenges. We follow with a range of implemented and proposed solutions to these challenges from both commercial and academic sources. Detailed comparisons in functionality, size and cost are drawn for a range of proposed metrics. We continue with solution recommendations for various functions and markets based on current technology and conclude with suggestions for future research and development.