Transistor Package TO-66 Case style, 2-Leads, 3-Terminal package.
TO-66 Package, Flange Mount
The TO-66 style case is a through-hole device in a metal package, similar to a number of other packages, including the TO-23 Case package, or TO-3 Case or TO-213AA case.
The diagram above shows the normal 2-terminal TO-66 pin locations, with the case used by the collector. The picture below shows the normal case attachment method for the TO-66 metal can. Note that the collector lead or metal case of the TO-66 is attached to a metal heat sink via two screws. A variant of this depiction uses a 3-Terminal TO-66 Package.
Case mount. [Flange Mount] A type of package which provides a method of readily attaching one surface of the semiconductor device to a heat dissipater to achieve thermal management of the case temperature. The case of a 2-Terminal TO-66 device is connected to the Collector to aid in heat dissipation.
Case temperature. Case temperature is that temperature measured at a specified point on the case of a semiconductor device.
TO-3 Metal Case
Normal TO-66 heatsinks are a Black Anodized Aluminum Alloy with 2 mounting holes. However any metal panel or metal plate may be used as a heat sink. In fact in many cases the TO-66 package is mounted external to a chassis to allow for better air flow [assuming a metal chassis. A possible heat sink is above, in the standard diamond shape conforming to the shape of the TO-66 outline. The actual length of the fins will vary depending on the heat sink purchased, but the physical size of the heat sink will conform to the body of the TO-66 [or just larger].
2-Terminal TO-66 Semiconductors;
The TO-66 package normally holds a high power Transistor;
NPN Power Transistor; 2N3584, 2N3585, 2N3739, 2N5660, 2N5661, 2N3766, 2N3767, 2N3879
NPN Power Switching Transistor; 2N5664 and 2N5665
NPN Power Darlington Transistor; 2N6300 and 2N6301
PNP Power Transistor; 2N3740, 2N3741
PNP High-Power Switching Transistor; 2N6211, 2N6212, 2N6213, 2N6213A
PNP Power Darlington Transistor; 2N6298 and 2N6299