New Roll-to-Roll Overmolding Technology for Creating Flexible Electronic Devices

Researchers at VTT Technical Research Centre of Finland have executed all manufacturing stages for a flexible in-molded LED foil -in roll-to-roll process for the first time. The purpose of this demonstration is to substantiate the suitability of the method for the extremely cost-effective manufacture of products such as flexible LED displays comprising of printed electronics.

All smart electronics used in products such as wrist-wearable computers are placed a sturdy board under the face of the watch. The roll-to-roll method enables electronics to be printed on an elastomeric foil or plastic, which has a variety of advantages such as lightness, thinness, transparency and elasticity. In hybrid-integrated systems, individual components are mounted on a printed electronic foil, after which the foil can be overmolded with thermoplastic elastomer or thermoplastic, using the injection molding process.

For the wristband demo, we performed all of the key manufacturing stages for printed hybrid systems - the printing of conductors, the assembly of semiconductor LEDs and the overmolding - using the roll-to-roll technique. This enables the mass manufacture of small-sized, easy-to-use, flexible electronics in a cost-effective manner.

Sami Ihme, Senior Researcher, VTT Technical Research Centre

In practice, the roll-to-roll overmolding of a printed electronic foil requires feeding of a LED foil with a foilfeeder into a mold, in which the overmolding is performed. This method is typically used to beautify plastic for a variety of consumer products. However, the manufacture of flexible electronics - instead of graphics - requires feeding electronics with a range of optical and electrical features into a mold.

Companies invited to create new products

The results have been promising. In the first test run for the overmolding of 186 LEDs, we achieved a 100% yield.

Sami Ihme, Senior Researcher, VTT Technical Research Centre

VTT Technical Research Centre of Finland Ltd is currently looking for product companies who might be interested in employing this new technology, in order to develop new commercial product concepts.

The demonstration will be exhibited at the international LOPEC fair for printed electronics in Munich, Germany between 29 and 30 March.