Thin gold metallizations are used in microelectronic devices when high reliability is required. Experience has shown that the operating lives of transistors and monolithic integrated circuits with high power dissipation, and of ultra-highfrequency devices such as microwave integrated hybrid circuits, are Longest when gold is used in the manufacture of their interconnections. With gold, the probability of zero-hour failures and of degradation under thermal and electrical bad, and in corrosive environments, is very low. The reasons for the high reliability of thin gold metallizations are to be found in the chemical stability of the metal, in the fact that ik is not very sensitive to diffusion from other metallizations and in the esse with which connections can be made to is by microwelding (1, 2, 3).