Application of Nano Silver sintering technique on the chip bonding for flip-chip and vertical light emitting diodes

Abstract

The bonding layer in the light emitting diode (LED) device of flip-chip or vertical structure is the most critical part to the device performance since it supports the electrical and thermal interconnection between the chip and its carrier. Therefore, the chip bonding process has become one of the major issues in the practical manufacturing. In this study, we developed a novel bonding technique using silver nano particle sintering. The raw bonding material with silver nano particles is in a paste form similar to the traditional Ag-epoxy. The entire bonding process is almost the same as the Ag-epoxy adhesive bonding. Meanwhile, it can provide excellent thermal and electrical performance better than the Ag-epoxy. Vertical and flip-chip LEDs were both chosen for demonstrating the silver nano particle bonding technique. After the test vehicles were prepared, diverse tests were conducted. The thermal performance was measured by the transient thermal analysis method. The electrical and optical performance were tested by an integrating sphere system. In addition, destructive shear tests were performed in order to characterize the shear strength. From the experimental results, it can be concluded that the silver nano particle sintering technique could be a promising bonding technique based on the assessment of performance, processing, and cost.