We have investigated thermal stability of the mechanical and thermal conductive properties of Cu/STS/Cu 3 layered clad metal lead frame material for a LED device package at different temperatures ranging from RT to $200^{circ}C$. The fabricated Cu/STS/Cu clad metal has a good thermal stability for the mechanical tensile strength and thermal conductivity of the over 50 $Kg/mm^2$ to the $150^{circ}C$ and 270 $W/m{cdot}K$ to the $200^{circ}C$, respectively. This clad metal lead frame material at a high temperature of $150^{circ}C$ shows a reinforced mechanical tensile strength by 1.5 times to conventional pure copper lead frame materials and also a comparable thermal conductivity to typical copper alloy lead frame materials.