B5.2 - Packaging Challenges for Monolithically Integrated Mircosensors

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
B5 - Sensor-Packaging
M. Streiff - Sensirion AG, Stäfa (Switzerland)
300 - 302


Within a time span of 12 years Sensirion has established itself as an industry leader in microchip based sensing of differential pressure, and flow measurement and control devices for gases and liquids. In particular, Sensirion is now regarded as the industry leader in combined temperature / humidity sensors, with respect to both market share and ability to innovate. This article will focus on humidity sensing, in particular, on the packaging challenges that were encountered on the path to a mature product, and on a preview of upcoming generations.

What makes a successful product? With respect to packaging the original vision was to offer customers products that look like and are assembled like any other standard IC component, i.e. products compatible with standard lead-free SMT processes using standard high volume placement and reflow solder equipment. Moreover, the challenge was to comply with tough AEC-Q100 testing conditions that include high temperature operating lifetime (HTOL), temperature cycles (TC), unbiased highly accelerated stress test (UHST), temperature humidity biased (THB), and ESD tests.
Finally, prior to Sensirion's technology, humidity sensors consisted of a sensitive element and discrete read out electronics and a trimming feature to calibrate the system. This resulted in bulky and expensive devices. Instead, the aim was to develop tiny, inexpensive, readily calibrated, highly stable and reliable components.

Naturally, package technology plays an eminent role in achieving all of these goals. However, the above vision has only become reality because Sensirion refined the following areas concurrently over the past years: packaging, sensor technology, testing, and calibration. For instance, by integrating the sensitive area and the read out electronics on the same monolithic chip, it was possible to radically reduce the footprint of a single components that is inexpensive, and can be tested and calibrated. Recently, these activities have culminated in starting the production of Sensirion's latest humidity sensor on a proprietary, fully automatic, high volume packaging line that was developed and built in-house.

In this way, accurate humidity and temperature measure-ments have become accessible to everyone and are ready to be integrate easily into any thinkable application.