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 Electronics packaging is a method of providing power and electrical distribution, mechanical protection and heat dissipation for integrated circuits. An integrated circuit (IC) package is a package that gives environmental protection to the IC chip whilst providing for different test methods and high quality assemblies at the next level of interconnection. Packaging is often considered the biggest bottleneck as it controls the system’s electrical performance, cost, size and reliability.
The major trend in the electronics industry today is to make products smarter, lighter, smaller, thinner, and faster, while at the same time making them more user and environmentally friendly, functional, powerful, reliable, robust, innovative, creative, and less expensive. Factors such as the feasibility of suitable substrates have to be considered when selecting a packaging alternative for the future. From this point of view, interconnection methods like flip chip become increasingly interesting.
Most research has addressed the challenge of making the “smallest structures” possible. Activities were mostly basic research oriented and resulted in a multitude of processes and small structures. Now, increased emphasis has been put on the device aspects and on the industrial application of these devices. The emphasis has been changed towards microsystems. This was done in order to concentrate on functionality and performance, rather than on small dimensions as well as highlighting the additional requirement to cover packaging, interconnection and interfaces. Even today, much research is based on using silicon technology.
Packaging and production options must be considered at an early stage of microsensor development. New silicon technology cannot be commercially successful until used in products and integrated with associated 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. There is therefore an obvious risk that packaging is regarded as a necessity that is not considered until the device is already designed and processed. It appears that 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 from the device’s initial design phase. The MEMS device must be designed for packaging and assembly. In other words, it must be producible in an industrial sense.
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, such as pressure sensors. 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, facilitating handling and simplifying assembly. The most important difference between packaging MEMS and microelectronics is the fact 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 have mechanical support, be protected against the environment, be easily mounted on circuit boards and facilitate easier handling of individual chips. In the case of MEMS, the device also needs to be protected at 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. This is so, as different sensor elements, electronics, complex optical elements and optical filters (in the case of optical sensors) and fluidic elements (in the case of biological and chemical sensors) will be combined. |