Transistor Can Package TO-23 Case style
TO-23 Transistor Case
TO-23 is a two lead through-hole device. The third terminal is the case.
Case mount. [Flange Mount] A type of package (outline) which provides a method of readily attaching one surface of the
semiconductor device to a heat dissipater or heat sink [shown above] to achieve thermal management of the case temperature. In most cases the collector of a transistor or drain of a field effect transistor will be the terminal connected to the case of the package. The terminal holes are not shown in the graphic of the heat sink. As the same basic shape could be used for a number of packages, with differing pin locations.
There are a number of other transistor packages that use this same diamond shape package style, but with different dimensions. Use the link to Transistor Package Styles to review similar package types, with a few already listed; for example TO-3 and TO66.
Editor note; JEDEC stopped using the TO-23 designation in 1987 because the case outline was considered inactive. So no devices produced after 1987 will be found using the TO23 package. However older components still in production could still be referred to as a TO23 package.
