Packaging and production options must be considered at an early stage of microsensor development. New silicon technology cannot be commercially successful until it is used in products and integrated with chips, packages, circuit boards, base plates, housings, connectors, displays, and switches. Many MEMS researchers are experienced in silicon processing and tend to concentrate on device fabrication, so there is an obvious risk that packaging is not considered until the device is already designed and processed. Packaging issues are often not taken into account until the industrialization stage of the product. This approach makes packaging very complex and expensive. Packaging must be considered at the very outset of the design phase. The MEMS device must be designed for packaging and assembly. In other words, it must be industrially producible.
Since MEMS often includes moving structures, the packaging requirements of such components must take this into account. Some functions also include interaction with the surrounding environment through pressure sensors, for example. This imposes new requirements on packaging, since, in normal microelectronics, the chip must be protected completely from any impact from the environment. Packaging also provides mechanical support to the sensitive chip in order to facilitate handling and simplify assembly. The most important difference between packaging MEMS and microelectronics is that MEMS is more often required to be in contact with the functional environment.
Most integrated sensors as well as integrated circuits require capsulation in order to provide mechanical support, to protect them against the environment, to facilitate mounting on circuit boards, and to make the individual chips easier to handle. In the case of MEMS, the device also needs to be protected at the wafer level in order to protect the structure from water and particle impingement during the dicing process. A higher level of integration will be required in future sensor systems becausedifferent sensor elements, electronics, complex optical elements and optical filters (for optical sensors) and fluidic elements (for biological and chemical sensors) will be combined.