While PCBs are used as backplanes for mini LED fine-pitch displays and mini LED backlighting currently, glass is expected to gradually replace PCBs as backplanes for mini LED backlighting beginning 2020 along with diminishing size of mini LED chips, according to industry sources.
PCBs, at current sizes of mini LED chips, have been used as backplanes for mini LED backlighting because of relatively low production cost and the flexibility that mini LED backlit LCD panels can be mosaicked into desired sizes, the sources said.
However, PCBs used as backplanes are not completely level and therefore, as mini LED chips get smaller, it is more difficult to directly transfer them onto PCBs, the sources noted. Glass backplanes are better options because of their levelness, the sources indicated.
China TFT-LCD panels makers reportedly plan to adopt mini LED backlight units (BLUs) using glass backplanes for 75-inch TV panels in 2020, the sources said.
At Touch Taiwan 2019 during August 28-30, vertically-integrated LED maker Lextar Electronics showcased an active matrix mini LED BLU with blue-light mini LEDs placed onto TFT glass backplanes using COG (chip on glass) technology to reach over 2,300 local dimming zones on a 2.9-inch panel, the sources noted. The BLU is suitable for use in VR displays.
At the exhibition, LED epitaxial wafer and chip maker Epistar and its subsidiary Yenrich Technology jointly showcased transfer of 0.02mm and 0.03mm mini LED chips onto glass backplanes.
Article translated by Adam Hwang
