Abstract: An ultra high frequency circuit formed on an insulating plate having first and second surfaces on opposite sides and having at least one hole formed through the plate and defined by a side wall connecting the surfaces. The side wall is covered by a deposition including overlapping layers of gold and gold-platinum for connecting, respectively, a gold connection track on the one surface with a silver alloy conductive layer. The overlapping gold/gold-platinum layers provide metallurgically-stable interfaces with the gold connection track and the silver alloy conductive layer. This prevents a metallurgically unstable condition which would exist if the gold connection track were directly connected to the silver alloy conductive layer. .