A flexible, thin and transparent light panel was developed by integrating a flexible LED foil with a plastic overmoulded structure. Source: VTTA flexible, thin and transparent light panel was developed by integrating a flexible LED foil with a plastic overmoulded structure. Source: VTTAdvertising boards may be getting a facelift in the near future after a project from the VTT Technical Research Centre of Finland and Neonelektro have developed new light-emitting diode (LED) displays that combine flexibility, low cost and high technical performance enabled by roll-to-roll mass manufacturing technology.

The OptIntegral project uses a hybrid integration manufacturing process that combines printed electronics with injection molding where the electronics substrate was immersed in an overmolded polymer. Overmolding protects components and enables additional features, such as optical and mechanical structures, to be integrated during a single process step.

The project applied the production to large-area LED displays and used overmolding to add optical structures to the display elements. This helped the visual appearance of the product but also lowered the temperature of the LEDs by about 20 percent, adding to the reliability and efficiency of the display.

The roll-to-roll process was used to make flexible LED substrates for the displays in order to increase productivity and Neonelektro developed an overmolded RGB display element using the technique.

"Flexible, lightweight, and of an easily customizable size, the LED advertising panel enables the creation of a dynamic look for a large area application, or those that require a 3D shape, such as vehicles," says Eveliina Juntunen, project manager of the project at VTT.

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