Gold-aluminium intermetallic
（重定向自Purple plague）
![A schematic cross-section of a purple plague in a wire-bond of gold wire on an aluminium pad. (1) Gold wire (2) Purple plague (3) Copper substrate (4) Gap eroded by wire-bond (5) Aluminum contact](/Images/godic/202502/05/Gold-aluminium_intermetallic.svg0629.png")
![Gold-aluminium phase diagram (German). Top axis title reads](/Images/godic/202502/05/Phasendiagramm_Gold-Aluminium.svg0629.png")
A gold-aluminium intermetallic is an intermetallic compound of gold and aluminium that occurs at contacts between the two metals.
These intermetallics have different properties than the individual metals which can cause problems in wire bonding in microelectronics. The main compounds formed are Au5Al2 (white plague) and AuAl2 (purple plague), which both form at high temperatures.