A method of fabricating a light emitting diode (LED) module comprising: providing a reflective cup containing at least one LED die ; positioning a solid piece in the cup and over the LED die, such that side edges of the solid piece abut the cup, while a bottom of the solid piece contacts a top of the LED die; the solid piece comprising: a binder having a first index of refraction and a first thermal conductivity; wavelength conversion particles mixed in the binder that convert first light emitted by the LED die to second light of a different wavelength; and high thermal conductivity particles mixed in the binder, the high thermal conductivity particles having a second index of refraction substantially equal to the first index of refraction such that the indices of refraction are matched to within 0.1 and having a second thermal conductivity greater than the first thermal conductivity; after the solid piece is positioned, softening the piece to flow the wavelength conversion particles, the high thermal conductivity particles, and the binder around the LED die to encapsulate the LED die and to conform the cup, wherein softening the piece comprises heating the piece to melt the binder; and hardening the softened piece after encapsulation of the LED die, wherein the hardened piece is configured to conduct heat from the LED die to the cup and to a base of the cup. providing a reflective cup containing at least one LED die ; positioning a solid piece in the cup and over the LED die, such that side edges of the solid piece abut the cup, while a bottom of the solid piece contacts a top of the LED die; the solid piece comprising: a binder having a first index of refraction and a first thermal conductivity; wavelength conversion particles mixed in the binder that convert first light emitted by the LED die to second light of a different wavelength; and high thermal conductivity particles mixed in the binder, the high thermal conductivity particles having a second index of refraction substantially equal to the first index of refraction such that the indices of refraction are matched to within 0.1 and having a second thermal conductivity greater than the first thermal conductivity; a binder having a first index of refraction and a first thermal conductivity; wavelength conversion particles mixed in the binder that convert first light emitted by the LED die to second light of a different wavelength; and high thermal conductivity particles mixed in the binder, the high thermal conductivity particles having a second index of refraction substantially equal to the first index of refraction such that the indices of refraction are matched to within 0.1 and having a second thermal conductivity greater than the first thermal conductivity; after the solid piece is positioned, softening the piece to flow the wavelength conversion particles, the high thermal conductivity particles, and the binder around the LED die to encapsulate the LED die and to conform the cup, wherein softening the piece comprises heating the piece to melt the binder; and hardening the softened piece after encapsulation of the LED die, wherein the hardened piece is configured to conduct heat from the LED die to the cup and to a base of the cup. <EOS>