Fan-Out Panel-Level Packaging of Mini-LED RGB Display

In this study, the feasibility of mini-light-emitting diode (LED) RGB display fabricated by a chip-first fan-out panel-level packaging is investigated. Emphasis is placed on the design, materials, process, fabrication, and reliability of the mini-LED RGB display package on a printed circuit board (PCB). The mini-LEDs under consideration and their sizes are red (<inline-formula> <tex-math notation="LaTeX">$125 \times 250 \times 100 ~\mu \text{m}$ </tex-math></inline-formula>), green (<inline-formula> <tex-math notation="LaTeX">$130 \times 270 \times 100 ~\mu \text{m}$ </tex-math></inline-formula>), and blue (<inline-formula> <tex-math notation="LaTeX">$130 \times 270 \times 100 ~\mu \text{m}$ </tex-math></inline-formula>). The spacing among the RGB mini-LEDs is <inline-formula> <tex-math notation="LaTeX">$80~\mu \text{m}$ </tex-math></inline-formula>, the pixel-to-pixel spacing is also <inline-formula> <tex-math notation="LaTeX">$\sim 80~\mu \text{m}$ </tex-math></inline-formula>, and the pixel pitch is <inline-formula> <tex-math notation="LaTeX">$625~\mu \text{m}$ </tex-math></inline-formula>. The temporary glass panel for making the redistribution layers (RDLs) of the package is <inline-formula> <tex-math notation="LaTeX">$515 \times 510 \times 1.1$ </tex-math></inline-formula> mm in size. To increase the SMT assembly yield on the PCB, the mini-LEDs are grouped into 4(<inline-formula> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> pixels)-in-one surface mount device (SMD), that is, a total of 12 R, B, and G mini-LEDs. A PCB (<inline-formula> <tex-math notation="LaTeX">$132\,\,mm \times 77$ </tex-math></inline-formula> mm) is designed and fabricated for the drop test of the mini-LED package. Thermal cycling of the mini-LED SMD PCB assembly is also performed by a nonlinear temperature- and time-dependent finite-element simulation.