Transistor Case Packages, Screw Mount

Bolt-Mount Packages

Transistor Package Screw Mount

Screw Mount BJT

Case Outline:
These packages are called screw-mount packages because the stud is threaded so the component may be attached to another surface, usually some form of heat-sink. The bolt or stub, which also happens to be connected to the rest of the metal case also acts as one of the terminals for the semiconductor held within. This happens to be a generic graphic, but there are many different styles and sizes, which is also why no physical dimensions are provided.

Case mount. A type of package (outline) which provides a method of readily attaching one surface of the semiconductor device to a heat dissipater [heat sink] to achieve thermal management of the case temperature.
This particular form of case mount is more commonly called a Stud Mount package, because of the mounting stud, or mounting bolt. Panel Mount may also be found as a related term.

There are a number of case types that use a Stud-Mount method.
DO-4; Case 56-02 [DO-203AA], Case 245, Case 311-02
DO-5; Case 257 [DO-203AB], Case 42A.

Types of Transistor case styles, or additional IC Package styles
Manufacturers of FETs and BJTs [Transistors], Heat Sink Manufacturers

A similar case style is a TO-61 package used for Transistors, or
D0-4 package used for diodes, both of which also uses a bolt or stud for mounting.

3-terminal TO-10 Transistor Package dimensions

TO-10 Outline Dimensions

The TO-10 case style is another example of a stud mount transistor package. The case is no longer in usage but of course was used with a number of transistors, including the 2N539. A low-power PNP Germanium transistor. With this transistor the collector is electrically connected to the case, so uses one of the three terminals and is also connected to the threaded stud. All three terminals have an eyelet with this particular package.


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