Thermal performance study of direct attached high-power LEDs using an innovative submount technique

The long-term stability of the optical properties of high-power LEDs like spectral emissivity and total luminous efficacy is still one of the big technical challenges in solid-state lighting. A basic requirement to guarantee the promised lifetime is to keep the maximum temperature during operation reliably below the specified value. With this respect, the thermal performance of innovative LED-sub mounts based on a thin bismaleimide triazine (BT) substrate with copper filled thermal vias for the direct attachment of high-power LEDs is investigated. The influence of the arrangement of the thermal vias and the copper structure as well as the impact of the degree of imperfectness of solder joints on the junction-to-case thermal resistance are revealed by thermal simulation. The thermal model is verified experimentally using a demonstrator set-up with a thermal resistance of ca. 11 K/W.