Large area displays composed of LED panels are being used for advertisement and announcements, for example in sport arenas. There can be up to millions of RGB-LEDs in one display. Each RGB-LED contains a blue, a green and a red emitting semiconductor chip. By steering the currents dedicated to each of these 3 chips, a large variety of colors can be achieved my mixing the emission spectra. Thermally stable silicones are used as encapsulants for the chips in the package.
However, the LED surface shows high tackiness caused by the soft silicone material, which may lead to problems during the manufacturing process of the LED as well as under operating conditions.
In the manufacturing process of display panels, the single LEDs are assembled to the board by a wave soldering process. Remanents of the LED stamping and bending process in the form of tin flakes accumulate in the soldering bath and frequently stick to the silicone surface of the LEDs and have a negative influence on the production yield. The tacki LED surface can also lead to problems during the pick and place process in the assembly of panels by sticking to each other or to the pick & place tool. This leads to lower production yield per time by many line stops. External influences during operation of the display, for example the collection of dust, accumulate over time to significant contaminations on the display.
By using the PlasmaPlus® - Technology, Plasmatreat has achieved the deposition of a thin, glas-like and anti-adhesive layer on the LED surface. This layer is highly effective versus any kind of contamination during manufacturing process and in later operation of the display, leading to increased production yield and longer lifetime of the display.