The technique could be used for the cost-effective manufacture of products such as flexible LED displays containing printed electronics.
"The results have been promising. In the first test run for the overmoulding of 186 LEDs, we achieved a 100% yield," says scientist Sami Ihme.
Smart electronics in products such as wrist-wearable computers are on a rigid board under the face of the watch. The roll-to-roll technique enables electronics to be printed on a plastic or elastomeric foil, which has various benefits such as thinness, lightness, elasticity and transparency.
"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 overmoulding - using the roll-to-roll technique. This enables the mass manufacture of small-sized, easy-to-use, flexible electronics in a cost-effective manner," explains Ihme.
In hybrid-integrated systems, separate components are mounted on a printed electronic foil, after which the foil can be overmoulded with thermoplastic or thermoplastic elastomer, using the injection moulding process.
In practice, the roll-to-roll overmoulding of a printed electronic foil involves feeding a LED foil with a foil feeder into a mould. This technique is normally used to decorate plastic for various consumer products.