Integration process allows ultra-thin systems

This ultra-thin chip package (UTCP) technology allows integrating complete systems in a low-cost flex substrate.

This paves the way to low-cost, unobtrusive wearable electronics for wearable health and comfort monitoring.

For the integration, the chip is first thinned down to 25 micron and embedded in a flexible ultra-thin chip package.

Next, the package is embedded in a standard double-layer flex printed circuit board (PCB) using standard flex PCB production techniques.

After embedding, other components can be mounted above and below the embedded chip, leading to a high-density integration.

The integration process uses UTCP interposers that solve the 'Known Good Die' issue by enabling easy testing of the packaged thin dies before embedding.

Expensive high-density flexible substrates can be avoided by the fan-out UTCP technology, which relaxes the interconnection pitch from 100um or lower to 300um or more, compatible with standard flex substrates.

IMEC has demonstrated the integration technology with a prototype flexible wireless monitor that measures the heart rate (electrocardiogram or ECG) and muscle activity (electromyogram or EMG).

The system consists of an embedded ultra-thin chip for the microcontroller and analogue-to-digital converter, an ultra-low power biopotential amplifier chip and a radio transceiver.

By thinning down the chips for UTCP embedding, they become mechanically flexible resulting in an increased flexibility of the complete system, making it unobtrusive and comfortable to wear.