While current flows within electronic components such as transistors, diodes, and voltage controllers, they dissipate power as heat energy. By exceeding a critical temperature, the heat will destroy the component. The consequence is breakdown of the electronic device. Therefore, heat must be removed from inside the device to maintain its normal operating temperature, this is typically acomplished by the use of a heat sink. Heat is transfered from inside the device to the heat sink by means of conduction (such as when the device is mounted directly to the heat sink) and to a lesser extent, radiation.