A suggestion for high power LED package based on LTCC

A high power package based on LTCC, multi layer ceramic-metal package, MLCMP, has been proposed. To comply with recent demands for high power LEDs, the proposed package utilized large scale via slug for heat sink slug whose cross section area is greater than ordinary LED die size. The via slug could be constructed in a single tiring process. The matching quality at the ceramic-metal interface was acceptable for reliable LED package and thermal conductivity of the sintered silver was assumed to be nearly equivalent to bulk silver. Thus, the proposed MLCMP is equivalent to existing heat sink slug type packages, where the chip is located on the metal heat sink slug and heat is efficiently transmitted to circuit board by the aid of the heat sink slug. Thermal resistance of MLCMP was evaluated numerically and experimentally. In the numerical simulation, MLCMP was compared with conventional heat slug type package and aluminum nitride based package. Thermal resistance of all the three packages is less than 10 K/W. As the cross section of the via slug increases, thermal resistance of MLCMP exceeds those of the two other packages. A transient thermal analyzer was used to measure actual thermal resistance of working MLCMP. The measured data were compared with analytic solutions. Thermal resistance contributed to MLCMP has been revealed to be less than 1.0 K/W. Considering the affordability and design flexibility, we anticipate the proposed MLCMP is not only suitable for high power LED package but also a promising solution for illumination modules.