Liu Jiaxin, Mou Yun, Huang Yueming, Zhao Jiuzhou, Peng Yang, Chen Mingxiang
School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
School of Aerospace Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Micromachines (Basel). 2022 Jun 17;13(6):958. doi: 10.3390/mi13060958.
The die-bonding layer between chips and substrate determinates the heat conduction efficiency of high-power LED. Sn-based solder, AuSn20 eutectic, and nano-Ag paste were widely applied to LED interconnection. In this paper, the optical-thermal performances and high-temperature reliability of LED with these bonding materials have systematically compared and studied. The thermal conductivity, electrical resistivity, and mechanical property of these bonding materials were characterized. The LED module packaged with nano-Ag has a minimum working temperature of 21.5 °C. The total thermal resistance of LED packaged with nano-Ag, Au80Sn20, and SAC305 is 4.82, 7.84, and 8.75 K/W, respectively, which is 4.72, 6.14, and 7.84 K/W higher after aging for 500 h. Meanwhile, the junction temperature change of these LEDs increases from 2.33, 3.76, and 4.25 °C to 4.34, 4.81, and 6.41 °C after aging, respectively. The thermal resistance of the nano-Ag, Au80Sn20 and SAC305 layer after aging is 1.5%, 65.7%, and 151.5% higher than before aging, respectively. After aging, the LED bonded with nano-Ag has the better optical performances in spectral intensity and light output power, which indicates its excellent heat dissipation can improve the light efficiency. These results demonstrate the nano-Ag bonding material could enhance the optical-thermal performances and high-temperature reliability of high-power LED.
芯片与基板之间的芯片键合层决定了大功率LED的热传导效率。锡基焊料、AuSn20共晶和纳米银膏被广泛应用于LED互连。本文系统地比较和研究了采用这些键合材料的LED的光热性能和高温可靠性。对这些键合材料的热导率、电阻率和机械性能进行了表征。采用纳米银封装的LED模块最低工作温度为21.5℃。采用纳米银、Au80Sn20和SAC305封装的LED的总热阻分别为4.82、7.84和8.75K/W，老化500h后分别升高4.72、6.14和7.84K/W。同时，这些LED的结温变化在老化后分别从2.33、3.76和4.25℃增加到4.34、4.81和6.41℃。纳米银、Au80Sn20和SAC305层老化后的热阻分别比老化前高1.5%、65.7%和151.5%。老化后，采用纳米银键合的LED在光谱强度和光输出功率方面具有更好的光学性能，这表明其优异的散热性能可以提高光效率。这些结果表明，纳米银键合材料可以提高大功率LED的光热性能和高温可靠性。
