A Review of Eutectic Au-Ge Solder Joints

Abstract

Gold-germanium (Au-Ge) joints have been part of the electronics industry since the birth of the solid state transistor. Today they find their role as a reliable joining technology, especially for high-temperature applications. This article is a literature study reviewing Au-Ge joints: Their uses, properties, material compatibility, application techniques, and performance characteristics. The review concludes that it is possible to create high-quality and very strong Au-Ge joints with a shear strength up to 150 MPa. They are stable and reliable, showing limited degradation after thousands of hours at high temperature and thousands of thermal cycles. Joints may be used in low-stress applications up to 300°C.

Thermodynamic Modeling of the Au-Ge-X (X = In, Sb, Si, Zn) Ternary Systems

“…Gold-based alloys, such as Au-Sn, Au-Sb, and Au-Ge eutectic alloys, are recognized for their exceptional corrosion resistance, high electrical and mechanical strength, and superior thermal conductivity. These attributes render them highly advantageous for electronic packaging applications [4][5][6][7][8]. Au-Ge-based alloys have especially attracted much attention as high-temperature Pb-free solders [4,9].…”

“…These attributes render them highly advantageous for electronic packaging applications [4][5][6][7][8]. Au-Ge-based alloys have especially attracted much attention as high-temperature Pb-free solders [4,9]. To mitigate the costs of Au-based alloys, alloying elements, such as Ag, Bi, Cu, Ga, Ge, In, Sb and Zn, can be introduced to partially replace Au.…”