Transistor Case Packages

TO-259 Package

Transistor Package TO-259 Plastic Encapsulated Case, Metal Plate

TO-259 Package out line and TO-259 Dimensions
TO-259 Transistor Package Out-line and Dimensions

TO-259 is a three-lead through-hole device with a metal plate for a heat sink. The metal tabs on both side of the metal body of the TO-259 act as a large heat-sink. The holes in the tab allow the package to be mechanically secured to another surface increasing the size of the heat sink.

Tab mount. The TO-259 type of package provides two tabs for attaching the metal surface of the semiconductor device to a heat sink to achieve thermal management of the case temperature. In this case the 'Tab' is an exposed metal die on the under-side of the component.
When possible the body of the TO-259 should be bolted to a metal heat sink or chassis wall using thermal grease or conductive epoxy. When the TO-259 is bolted to a printed wiring board a large copper pad should be located beneath the exposed die to conduct heat into the PWB and away from the body of the TO-259. The copper pad or island could extend to copper plane to increase the metal and further dissipate the heat. Thermal vias may be used to conduct heat through the PWB to the opposite side of the board.

Insulated Gate Bipolar N-Channel Transistor; 2N7368 [one example of a TO-259 device]

Types of Transistor cases; BJT Package styles.
Manufacturers of FETs and BJTs [Transistor Manufacturers]

Editor note: The package shown above may be indicated as a TO-259 (p), while if the package is indicated as a TO-259 (N) the device may only have one tab located at the top [back] of the device, which is the common tab location for a vast number of other packages. However other data sheets do not use the (P) to define the package.

The acronym BSC stands for Basic Spacing Center, and means basic spacing between centers. An acronym used to denote a dimension that can change with conditions. Using the dimensions table data as an example; the pin-to-pin spacing [LS] could change while handling or when inserting the part into a printed wiring board. The same situation could occur with the pin spacing centered on the body of the part [LO]. In other words the dimension is nominal or 'basic' as the acronym implies.

Transistor Package
Flange-Mounted Header Family

TO-259 Dimensions
TO-259 Package Dimensions

TO-259 Common Usage:
Center-taped Schottky Rectifier
Common Cathode, Common Anode

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