Development of Metal Bonding for Passive Matrix Micro-LED Display Applications

Recently, there are many breakthroughs of display in the high resolution and vivid colors for applications in virtual/augmented reality. In this study, we have successfully developed a 64 ×32 array inline structure of a micro-LED ( μLED) display by metal bonding an LED array with a glass circuit for connecting a passive matrix IC driver. The dimension of each μLED was 100 μm ×100 μm. After bonding, the optoelectronic characteristics were measured to evaluate the best process. By the circuit fabricated on glass and by using a bonding design, we were able to increase the usage ratio of the epitaxy layer and reduce the cost of the μLED display. Au-In metal bonding demonstrated an excellent bonding result that can withstand a shear force up to 12.58 kg after being reinforced with UV glue. The output power of the display was 61 mW under 120 mA (@1.9 V) current injection to the whole display and the wall plug efficiency is 26.75%.