Effect of microstructure of Au80Sn20 solder on the thermal resistance TO56 packaged GaN-based laser diodes

Abstract

Au80Sn20 alloy is a widely used solder for laser diode packaging. In this paper, the thermal resistance of GaN-based blue laser diodes packaged in TO56 cans were measured by the forward voltage method. The microstructures of Au80Sn20 solder were then investigated to understand the reason for the difference in thermal resistance. It was found that the microstructure with a higher content of Au-rich phase in the center of the solder and a lower content of (Au,Ni)Sn phase at the interface of the solder/heat sink resulted in lower thermal resistance. This is attributed to the lower thermal resistance of Au-rich phase and higher thermal resistance of (Au,Ni)Sn phase.

Controllable step-flow growth of GaN on patterned freestanding substrate

“…Surface morphology was studied by atomic force microscope (AFM, Bruker Dimension ICON) in tapping mode. AFM amplitude images were used to clearly show atomic step features even on tens of microns large surface with huge height differences [26] . The miscut information was obtained by the analysis of peak positions of Xray rocking curves (XRD, Bruker D8 Discover) by rotating the samples around the surface normal.…”