TO-leadless
A TO leadless package is a TO package without connection legs. Such a package is suitable for Surface Mounted Technology ( SMT).
TO-Leadless packages are designed for power semiconductors with high current densities such as transistors, MOSFETs, IGBTs and GTO thyristors and are characterized by good heat dissipation. TO-Leadless packages have lower package resistance than TO packages, they are compact and offer good electromagnetic compatibility( EMC).
The package resistance is enormously important because of the current density and depends on the length, cross-section and material of the lead and bonding wire. With TO-Leadless, the resistance values are around 0.3 milli-ohms.