Improving Transfer Accuracy of LEDs Utilizing the Alignment Structure

Laser-assisted transfer technology is an effective method for large-scale transfer of LED chips, particularly in micro/mini LED manufacturing where high-density integration and miniaturization are essential for advanced displays. However, significant position deviation issues are observed in the transferred LED chips owing to the uncontrolled free fall process. In this study, a chip transfer alignment structure is designed and fabricated using 3D printing technology and integrated into the polydimethylsiloxane (PDMS) stamp transfer process. This alignment structure utilizes a combination of slanted and vertical holes to guide the chip into the correct landing path. Experimental optimization identifies the optimal parameters for the slant hole angle, vertical hole dimensions, and the depth ratio between slant and vertical holes. Compared to a control group that did not utilize the alignment structure, the average center deviation and angular deviation of the transferred micro - LED chips were reduced by 62.1% and 79.3%, respectively, leading to a significant improvement in precision. Furthermore, the integrity and brightness uniformity of the LED chips were almost unaffected by the integration of the alignment structure. In the future, further optimization of the alignment structure’s geometry and integration with other functional materials could further enhance the precision and efficiency of the transfer process.