Leuven, Belgium: A new 3D integration process will help foster a new level of flexibility in wearable electronics such as health and comfort monitoring. An ultra-thin chip package (UTCP) technology developed by IMEC and Ghent Univ. makes it possible to integrate complete, flexible electronic systems measuring less than 60 µm thick into a conventional low-cost flex substrate.
UTCP interposers simplify the testing of packaged thin dies before embedding, which alleviates the known-good die problem. Expensive high-density flexible substrates can be avoided, too. The fan-out UTCP technology relaxes the interconnection pitch from 100 µm or lower to 300 µm and up, making it compatible with standard flex substrates.
In the integration process, the chip is first thinned down to 25 µm and embedded in a flexible ultra-thin chip package. Then the package is embedded in a standard, double-layer PCB using standard flex PCB production techniques. Once embedded, other components can be mounted above and below the chip.
At the Smart Systems Integration Conference on10 March 2009, IMEC demonstrated the technology with a prototype flexible wireless monitor for heart rate (electrocardiogram, or EKG) and muscle activity (electromyogram, or EMG) measurements. The total system includes the embedded ultra-thin chip for the MCU and ADC, an ultra-low-power biopotential amplifier chip, and a radio transceiver.