In our previous post: “Want help choosing the correct LED Driver?”, the term Thermal Runaway was referenced. Thermal Runaway leads to current crowding and the development of current filaments, which happens to be one of the primary causes of a semiconductor failure.
It all starts with the profile of silicon. The electrical resistance of silicon increases with temperature up to about 160 Celsius, then starts decreasing. When resistance decreases, it allows more current to enter through the overheated areas, in turn causing yet more compounding heat, eventually leading to total failure of the device and hence the term Thermal Runaway.
With adequate thermal management and the use of a constant current driver, an LED will not exceed its maximum operating temperature and will never approach Thermal Runaway.