Ultra-thin chip packages could lead to intelligent clothing

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Imec claims it has integrated an ultra-thin, flexible chip with bendable and stretchable interconnects into a package that adapts to curving and bending surfaces.

According to a statement, the resulting circuitry can be embedded in medical and lifestyle applications where user comfort and unobtrusiveness is key, such as wearable health monitors or smart clothing.

The researchers presented their results at this week’s 2012 Electronics System Integration Technology Conference (ESTC) in Amsterdam.

Currently, most electronic appliances are rigid or mechanically flexible, but a growing number of applications require electronics that dynamically adapt to curving and bending surfaces.

Examples include biomedical systems such as unobtrusive, wearable health monitors (electrocardiograms or temperature sensors), advanced surgical tools or consumer electronics such as mobile phones embedded in smart textiles.

Imec’s associated lab at Ghent University is said to have pioneered this technology, moving it towards industrial applicability.

For the demonstration, the researchers thinned a commercially available microcontroller down to 30µm, preserving the electrical performance and functionality.

This die was then embedded in a polyimide package (40–50µm thick). Next, this ultra-thin chip was integrated with stretchable electrical wiring.

These were realised by patterning polyimide-supported meandering horseshoe-shaped wires — a technology developed and optimised at the lab.

Finally, the package is embedded in an elastomeric substrate (such as polydimethylsiloxane [PDMS]) where the conductors behave as two-dimensional springs, enabling greater flexibility while preserving conductivity.

‘Future electronic circuitry will stretch and bend like rubber or skin while preserving its conductivity,’ said Jan Vanfleteren, responsible for the research on flexible and stretchable electronics at Imec’s Ghent lab. ‘This breakthrough achievement demonstrates that flexible ultra-thin chip packages can be integrated with stretchable wiring, paving the way for fully flexible applications.

‘We anticipate the first appliances will be used in intelligent clothing, with medical applications following later. Once commercial products are introduced, I expect to see clothing with signalisation by using LEDs and sensors to track movements.’

This research was supported by the Agency for Innovation by Science and Technology in Flanders (IWT) through the SBO-BrainSTAR project. Imec added that industrial partners are welcome to join the research and development programme.