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Characterization of Die-Attach Thermal Interface of High-Power Light-Emitting Diodes: An Inverse Approach

An advanced inverse approach, based on the transient junction temperature behavior, is proposed and implemented to quantify the resistance of the die-attach thermal interface (DTI) in high-power light-emitting diodes (LEDs). After describing the unique transient behavior of high-power LEDs associated with the forward voltage method, a hybrid analytical/numerical model is used to determine an approximate transient junction temperature behavior, which is governed predominantly by the resistance of the DTI. Then, an accurate value of the resistance of the DTI is determined inversely from the experimental data over the predetermined transient time domain using numerical modeling. The proposed inverse approach is capable of determining the DTI to an accuracy of 0.01 K/W, which is sufficiently high to evaluate the die bonding manufacturing processes.