TO-39 Package
Transistor Can Packages TO-39 Case, Through-Hole
 4-Terminal TO-39 Package | The package out-line provided to the left shows a 4-terminal TO-39 package. The particular pin out shown for the terminals is but one example or what a package could have. In the case one of the terminals indicates that there is a connection to the metal case. In fact the terminal is shorted directly to the case, which is shown by the smaller circle which represents the pin. The pin is shown smaller because there is no separation between the pin and the case, it's not insulated from the case. The other pins could of course have any function, but are shown as input, output and V [for supply voltage]. The physical outline and dimensions are identical to a standard TO-39 package, with the exception of the four terminal. Note that the other pages might use different symbols to indicate the dimensions, but it's the actual dimensions that are important not the symbol that represents them. |
The TO-39 package is a through-hole device [metal can].
The TO-39 Can is a common through-hole package, common with transistors.
This example of a TO-39 metal-can contains an Operational Amplifier and has four terminals; Input, Output, [+V] Vcc, and [-V], which is also connected to the case Case. Any other three or four terminal component could also use the package, except in this case an example pin-out is provided in the graphic. Normal heat-sinks for the TO-39 will snap-on to the top of the metal case, other Solid aluminum heat-sinks slide over top of the TO-39.
Editor note: The heat sink drawing above shows an example of one style of a clip-on, or press-on heat-sink. There are many different styles of heat sinks produced for semiconductors in a round metal can. Many of the pages covering the different styles or shapes of transistor packages provide a different version of heat sink. In general the metal cans use some type of slip-on heat sink, although the the actual shape varies.
Mounting Recommendation: Mount the component near the printed wiring board, so the leads are kept short. However don't mount the metal-can so close to the board that the surface of the package shorts out any traces running beneath it. In fact, don't place the package so near the board that a spacer is than required as a board separator, as it becomes a new line item on the parts list to track.
