Transistor Case Packages

TO-61 Package

Transistor Packages Styles TO61 Case style, Bolt Mounting

TO-61 Package Drawing

TO-61 Outline As of 1996 JEDEC [Joint Electron Devices Engineering Council] considers the TO-61 case outline inactive for use and has removed the designation. So no new devices developed after 1996 would use the TO-61 designation. However any component still manufactured would still carry the TO-61 designation. Any data sheet produced for any transistor in this package will also indicate the TO-61 outline. There doesn't appear to be any newer outline designation for this package style. That is, an identical outline with a different designation. So care should be taken to insure a replacement part has the same physical dimensions.

The TO-61 package is a high-power through-hole Bolt-mount device with 10-32 threads.
Yet another type of component that connects to the circuit by flexible wire, or wire leads from the three terminals. Use the largest wire possible to insure the wire resistance is kept to a minimum. Of course wire diameter can't be larger then the cut-out on the terminal. The lead-wires should also be kept as short as possible to minimize wire resistance.

Terminal Leads; Lead 1 Emitter, Lead 2 Base, Lead 3 Collector.
The metal stub is threaded so the component can be secured to a mounting surface or metal heat-sink.

Case mount. Also called a Bolt-Mount package or Stud Mount package. A type of package which provides a method of readily attaching one surface of the semiconductor device to a heat-sink to achieve thermal management of the case temperature [Metal panel, heat sink, copper plane]. The TO-61 Case is isolated from any of the terminal leads. A similar bolt-mount style is the TO-59 Transistor case or TO-63 Transistor case, however there are a number of packages that are basically a bolt mount device.

TO-61 Semiconductor Devices:
NPN Power Transistor using a TO-61; 2N6691, 2N6693
NPN High Power Transistors that use the TO-61 package; 2N2812, 2N2814.

The orientation of the terminals in relation to the hex flats is not controlled, and is not controlled with any of the similar packages listed above either.
No heat sinks are identified for this package type, as the package shape is designed to mount to a heat sink, or a component that acts as a heat sink [an equipment chassis or flat panel].