Theoretical and Experimental Studies of Chip Position Drift in Motional Chip Placement Process

Accuracy and efficiency of chip placement process play a critical role in electronic packaging technology since it can determine the success ratio and throughput of chip packaging system. In this paper, a new motional chip placement process is proposed to improve the process efficiency, where the chip is placed onto the substrate with a contact velocity. However, the moving chip is also more likely to produce position drift on the anisotropic conductive adhesive, which will result in low accuracy of chip placement process. In view of this, a three-layer model considering the effect of the chip contact velocity is presented to address the dynamic behavior of chip placement process, where the geometrical dimensions and material properties of this model are included. In addition, the mechanism of motional chip placement process is uncovered, and the effects of key factors, including chip length, adhesive viscosity, and chip contact velocity on chip motion, are analyzed. The results show that the moving chip is helpful for the efficiency of chip placement process, but it also may cause low accuracy of chip placement process. Finally, in order to select appropriate key factors, the technical criteria are discussed, and the process window for reliable motional chip placement is established and verified by experiments.