A Novel Chip Placement Technlogy for Fan-Out WLP using Self-Assembly Technique with Porous Chuck Table

Abstract

This paper reports on a novel chip placement technology for Fan-out WLP using expansion technology and self-assembly technique. In a preceding paper, we reported that we have developed the novel tape expansion machine which can expand the tape in four directions individually. Using this expansion machine device, we have developed the high expansion tape which can obtain the required chip distances for Fan-out WLP. Since Fan-out WLP requires significantly higher precision process than traditional electronics devices, we try to improve higher placement accuracies after tape expansion. In this research, we propose the novel chip placement process that combines the porous chuck table with self-assembly technique which is known for higher placement accuracy process. Our proposal process is carried out as follows. 1) Transfer expanded chips to the porous chuck table, 2) Supply the liquid from the porous chuck table to the table surface where hydrophilic area is formed, 3) Precise alignment by self-assembly technique using liquid surface tension, 4) Recover the liquid in the porous chuck table. Since the liquid is supplied and recovered by using the porous chuck table, higher throughput is enabled compared with the conventional process. As a result of evaluation, the chip placement accuracy is less than $30 \mu \mathrm{m}$ using the prototype porous chuck table. We indicate that both high placement accuracy and high throughput can be achieved by using our novel chip placement technology.