In one embodiment, a lamp comprises an optically transmissive enclosure. An LED array is disposed in the optically transmissive enclosure operable to emit light when energized through an electrical connection. A gas is contained in the enclosure to provide thermal coupling to the LED array. A board supports lamp electronics for the lamp and is located in the enclosure. The LED array is mounted to the board and LEDs are mounted on a submount formed to have a three dimensional shape. The board is electrically coupled to the LED array and the submount may be thermally coupled to the gas for dissipating heat from the plurality of LEDs.