VTT Technical Research Centre of Finland Fabricates Flexible LED Foil with Roll-to-roll Process

The VTT Technical Research Centre of Finland reports that it for the first time was able to use a roll-to-roll process to perform all the manufacturing stages for a flexible in-molded LED foil. The demonstration’s purpose is to prove the suitability of the fabrication method for the highly cost-effective manufacture of products including flexible LED displays with printed electronics.

Virtually all smart electronics in products such as wrist-wearable computers are on a rigid board under the face of the watch.

However, the newly developed roll-to-roll fabrication technique enables electronics to be printed on a plastic or elastomeric foil. Such foils benefit from light weight, thinness, elasticity, and even transparency. In hybrid-integrated systems, separate components can be mounted on a printed electronic foil. Then, an injection molding process is used in the overmolding with thermoplastic or thermoplastic elastomer.

“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,” said Sami Ihme, senior scientist.

In practice, roll-to-roll overmolding of a printed electronic foil involves feeding an LED foil with a foil feeder into a mold. Then, the overmolding is performed in this mold. Manufacturers normally use this fabrication technique to decorate plastic for various consumer products. However, the production of flexible electronics instead of using graphics involves feeding electronics with a range of electrical and optical features into such a mold.

Companies Sought 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,” explained Ihme.

VTT Technical Research Centre of Finland Ltd says it is now seeking product companies that would like to try this new technology to create new product concepts.

VTT Technical Research Centre is presenting the roll-to-roll process demonstration at the international LOPEC fair for printed electronics in Munich, Germany on 29–30 March.

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