Vacuum-baking encapsulation techniques and improved reliability of NPN alloy transistors

Other investigators have reported that improved reliability for NPN alloy transistors can be expected with vacuum baking and vacuum encapsulation of the device. Our pilot shop experience with relatively large numbers of NPN alloy transistors has demonstrated that vacuum encapsulation does offer definite gains in reliability over earlier methods for encapsulation. An extension of this encapsulation technique involving employing a gettering agent results in further improvement in the stability of the device characteristics with time. Feasibility of use of these encapsulation procedures in high level production has been achieved through design of the high-vacuum station and the procedures associated with its operation. Details of the equipment and process and plots of transistor parameters versus time will be presented.