Packaging Technology for Devices in Autonomous Sensor Networks

Abstract

Autonomous sensor network (ASN) node comprises of multiple miniaturized sensors, actuators, controller-circuitry and power source. Packaging and integration of these components play a critical role in determining the overall system performance, cost and time to market. Packaging of electronic components provides significant improvement in device characteristic performance and ensures long-term reliability. Packaging of ASN nodes and/or its components is more challenging, because of the sheer variety of components, like sensors, actuators, integrated circuit (IC) controllers, that make up the ASN nodes. Numerous packaging solutions like assembling individually packaged components on a single board (printed circuit board level packaging) or housing all components in a single package (system-in-package or system-on-chip approach) have been demonstrated. Some of the popular and commercially available chip-level packaging technologies are wire bonding, flip-chip bonding, tape automated bonding, etc. However the cost for these conventional chip-level packaging is much higher than other cost associated with device manufacturing. Thus wafer-level packaging has gained interest as it can be used as a low cost packaging technology. In this chapter, packaging of infrared (IR) sensors has been used as a case study to demonstrate the packaging constraints imposed by device performance and application requirements, followed by brief discussion on various packaging solutions available for individual IR sensor and more sophisticated IR sensor array. As future outlook, it seems possible to integrate all the components of ASN node, except for the battery power source. To tackle this technology constraint, energy harvesting technology has been investigated as an alternative power source. Thus replacing the battery by energy harvesters as power source is discussed at the end of this chapter.