Study Of Flip Chip LED Packaging And Heat Dissipation

Compared with traditional TS chip and vertical chip, Flip-chip LED package has the advantage of high reliability, low thermal resistance and overdriving. Flip-chip LED package has gained popularity due to its advantages since its volume production. In the meantime, problems arise for the flip-chip package in terms of dimension mismatch between the chip electrodes and the lead frame, and CTE mismatch between the GaN materials on chip and the lead frame.In order to reduce the mismatch between the chip and frame, a thin film made of silicone and thermally conducted material is placed between the chip and frame. In this paper, the influence of thermally conductive materials on the package performance was investigated in terms of aluminum nitride, aluminum oxide and thermal plastic. The results show that the higher thermal conductivity of filling, the better thermal performance of the packaged device. On the other side, compared with no filling, the filler can reduce lumen flux of the package device by 2-5%. In the aging process, we found that the radiant flux of filling package device is 3-5% higher than those of unfilled for 240 hours. The filler with mixture of aluminum nitride and silicone by 2:1 has the best lumen maintenance rate. After 168 hours aging, radiant flux with aluminum nitride filler is higher than those of other fillers. Results show that filler is effective for long aging process of the package. The opto-electrical performance, heat dissipation and aging properties of packages with different fillers, different chips and different led frames were also investigated.