What is TO-220 package? TO-220 package means TO220 Package. The TO-220 is a style of electronic component package, commonly used for transistors, silicon-controlled rectifiers, and integrated circuits. TO-220 packages commonly have three leads although units with two, four, five or seven leads are also manufactured. A notable characteristic is a metal tab with a hole, used in mounting the case to a heatsink. Components made in TO-220 packages can handle more power than those constructed in TO-92 cases. 3 pin TO-220 package image 5 pin TO-220 package image 7 pin TO-220 package image 9 pin TO-220 package image 11 pin TO-220 package image 27 pin TO-220 package image