Once the OLED layers are complete, the film is separated from the glass substrate by sublimation with a UV laser (laser lift-off).
Solid-state lasers are now also available for use with this process. With a comparable output, these lasers are superior to the excimer lasers that have typically been used up to now, primarily in terms of operating costs. Solid-state lasers deliver excellent beam quality, usually in a Gaussian beam profile. With the aid of special micro-optics, several of these laser sources are transformed into the profile needed for LLO, with lengths of up to 1,000mm and widths of less than 50µm. For example, LIMO’s Activation Line UV line beam shaping system has been used for years with great success for OLED lift-off processes in the production of flexible mobile phone displays.
The development team at LIMO has now enhanced the optical design far enough that the Gaussian profiles can be turned into a line with a length of up to 1,000 mm and a width of 30µm. The new features include significantly steeper edges and a wider intensity maximum. This allows the laser energy to be used much more effectively to separate the display film, and LLO process productivity can be increased by more than 30%. In addition, the sensitive OLEDs are subjected to lower thermal loads (lower ash value), yields are higher, and the OLED displays produced have a longer lifespan.
The new micro-optics for the sGauss profile are modular and feature a continuously adjustable line length and width. Existing systems can also be retrofitted with an sGauss module. This allows manufacturers to either directly boost productivity or, where less laser energy is used with the same systems, significantly extend the service life of their lasers.
LIMO GmbH – www.limo.de