3-D highly precise self-alignment process using surface tension of liquid resin material

Abstract

A novel self-alignment process using the surface tension of the liquid resin for assembly of electronic or opto-electronic devices in 3-D space has been proposed. The vertical alignment can be controlled by using of metal sphere, reducing the necessary precise process control such as solder volumes and external forces, and allowing large tolerances in liquid volume and misalignment. Lateral alignment could be also achieved by making the liquid resin constrained on the 3-dimensional pads on chip and substrate. This study focused on the principle of self-alignment and final alignment accuracy. In addition, the possibility of self-alignment process was verified by analytic numerical method and scaled-up experiment. An average alignment accuracy of less than 0.25 muM has been obtained. It is thought that this process is effective for assembly simply at low process temperature, low cost and without flux in future assembly techniques.