Gang Bonding Process of Flip-chip Mini-LED for the Assembly of High Pixel Density RGB Display Panel

Abstract

In this article, we reveal an innovative gang bonding process of mini-LED for assembling the high pixel density RGB display panels which are used for constructing large indoor or outdoor color display [1]. The direct chip-on-board bonding of flip-chip mini-LED on printed circuit board (PCB) is realized by gang thermal compression (TC) bonding process. New assembly process flow for making high pixel density RGB display panel will be described in detail. It consists of four processing steps, which are: (i) pick and place of RGB mini-LED from known good wafer onto a carrier with electrodes facing up forming RGB mini-LED matrix, (ii) forming solder bumps on each bond pad on the PCB by stencil printing of solder paste and oven reflow processes, (iii) TC gang bonding of the mini-LED matrix on the carrier to the PCB substrate after precise vision alignment, and (iv) complete the whole panel by stitch-bonding of the mini-LED matrices.