transistor outline (transitor package) (TO)
The TO package, TO stands for Transistor Outline, is one of the first standardized transistor packages. The standardization of package formats has contributed to cost reduction and improved assembly techniques.
The TO package is a high quality package available in various sizes and designs, as round or flat packages made of metal or plastic, and with a different number of connections.
Well-known TO designs are TO-3, TO-5, TO-8, TO-18, TO-39, TO-66, TO-72, TO-92, TO-126, TO-218, TO-220, TO-247, TO-252, TO-254, TO-257, TO-258 and TO-264. The TO package is for through-hole technology( THT) and is used for general-purpose transistors, for RF transistors and power transistors, for field-effect transistors( FET), Darlington transistors, and for transistor circuits. The TO-252 package is footprint equivalent to the DPAK package, TO-263 is footprint equivalent to the D2PAK package.
The TO package is also available without leads as TO leadless for SMT technology. The TO-Leadless packages are especially for power semiconductors.