Ablation morphology and characteristic analysis of anisotropic conductive film (ACF) using femtosecond lasers with NIR, Green, and DUV wavelengths for micro-LED display repair

Anisotropic conductive film (ACF) is an electrical and electronic material composed of conductive balls embedded in a polymer matrix. ACF plays a crucial role in connecting electrodes and chips in Micro-LEDs. It serves as the target material in the repair process, enhancing production yield. For the application of ACF in the Micro-LED display repair process, flawless selective micro-ablation is essential. However, little research related to ACF micro-ablation has been conducted so far. In this study, we investigated a detailed analysis of the ablation area and defects in ACF by using femtosecond lasers with three different wavelengths: 1026 nm (NIR), 513 nm (Green), and 257 nm (DUV) for selective micro-ablation. By conducting a comparative analysis of these wavelengths, we determined that the optimal ablation results were achieved using a 257 nm wavelength femtosecond laser. These results exhibited no-defect, uniform, reproducible, and symmetrical ablation characteristic, making it suitable for the Micro-LED display repair process. This research is expected to establish the foundation for micro-ablation in all applications where ACF is employed.