There are very few uses of Fernico.

Metal alloys (such as Cunife and Fernico) and glasses had been developed for light bulbs that expanded and contracted in similar amounts, as temperature changed.

The family includes Kovar, FerNiCo I, FerNiCo II, and Dumet.

Electrolytic effects from the differing metals used for the miniature tube pins (usually Cunife or Fernico) and the tube base could cause intermittent contact due to local corrosion, especially in relatively low current tubes such as were used in battery-operated radio sets.

Without forensic photography equipment such as Fernico ZRT, EDEC Eclipse, or Project-a-Phone, this had the disadvantage of risking the modification of the device content, as well as leaving many parts of the proprietary operating system inaccessible.

Because the pins are actually the Fernico or Cunife lead-out wires from the tube itself, they are prone to intermittent connections caused by the build-up of electrolytic corrosion products due to the pin being of a different metallic composition to the socket contact.