Failure analysis of cracked brass turrets used in electronic circuits

Copper alloys are widely used in electrical circuits mainly due to their electrical conductivity. In electrical circuits, solder terminals are used to provide multiple electrical connections and swage type turret terminals are preferred owing to their high reliability under dynamic environments where the electrical systems are subjected to higher vibrations and line currents, as in the case of satellite launch vehicles. Owing to high machinability, free-cutting brass is preferred in the manufacture of such small sized terminals, which will be cold worked/swaged to the printed circuit boards. Improper selection of the composition of free-cutting brass can lead to cracking of the terminals, thereby affecting the reliability of the system. This paper describes cracking of turret terminals made of free cutting brass during swaging operation. The crack propagation tendency during cold working of brass turret terminals made from different compositions is studied through optical and scanning electron microscopy. Finally, composition for obtaining crack free terminals during swaging is suggested for applications involving cold swaging.