基于ANSYS Workbench半导体激光器封装热特性分析Analysis of Thermal Characteristics of Semiconductor Laser Packaging Based on ANSYS Workbench

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Based on the theoretical analysis of the thermal characteristics of semiconductor lasers, the model of c-mount packaging is established by using ANSYS Workbench software. The temperature and heat flux distribution of single-tube semiconductor laser chips are simulated and analyzed. When the output power is 10 w, the temperature of traditional c-mount packaging chips is 66.393˚C, and thermal resistance is 4.6 k/w. By adding a layer of graphene with high thermal conductivity be-tween the heat sink and the laser chip, the heat flux diffusion area is increased; the temperature of the chip is reduced to 55.587˚C; the thermal resistance is 3.5 k/w; and the heat dissipation effect is obvious. The maximum output power is increased from 15.4 w to 18.5 w. It is found that the output power is increased by 20%.

1. 引言

2. 理论分析

1) 当电流注入有源区且小于阈值电流时，器件发出微弱的自发辐射光，没有激光产生，这部分注入的电流主要产生废热，热功率密度为QNR

${Q}_{NR}=\frac{1}{d}Uj\left(1-{\eta }_{i}\right)$ (1)

${Q}_{act}=\frac{{V}_{j}\left(1-{\eta }_{sp}{f}_{sp}\right)}{{d}_{act}}\left[{j}_{th}+\left(j-{j}_{th}\right)\left(1-{\eta }_{i}\right)\right]$ (2)

${T}_{j}={T}_{sink}+\left(IV-P\right){R}_{th}$ (3)

${I}_{th}={I}_{th}\left({T}_{r}\right)\mathrm{exp}\left(\frac{T-{T}_{r}}{{T}_{s}}\right)$ (4)

2) 除有源区外各层外延材料的损耗及电极层的电阻生成的热。

(5)

Q为热功率密度，pi为每层材料的电阻率。

3) 半导体激光激光器稳定的工作后的热传导方程为：

$K\left(\frac{{\partial }^{2}T}{\partial {x}^{2}}+\frac{{\partial }^{2}T}{\partial {y}^{2}}+\frac{{\partial }^{2}T}{\partial {z}^{2}}\right)+Q=0$ (6)

$\eta =\frac{P-{P}_{th}}{I-{I}_{th}{h}_{v}}$ (7)

$P={P}_{th}+\frac{{\eta }_{ex}{E}_{p}}{e}\left(I-{I}_{th}\right)$ (8)

Pth为阈值电流下激光器光功率，ηex外微量子效率，Ep为光子能量，e为电子电荷，I为激光器驱动电流，Ith为阈值电流。

$\eta =\frac{P}{IV+{I}^{2}r}$ (9)

1) 半导体激光器工作过程中，内部的电子-空穴非辐射复合转换成光子产生的热量为主要热源。

2) 半导体激光器芯片腔长1.8 mm，热功率为10 W，热功率密度为7.407 × 109 W/m3，且各个外延

Figure 1. Workbench Model of c-mount package structure

Table 1. Material parameters of the laser

3) 由于激光器芯片尺寸很小且非常薄，模拟过程计算温度不高，忽略芯片各个面的热辐射及空气对流散热。

4) 模拟计算中热沉下表面恒温20℃，同时选择两种热导率不同的焊料AuSn焊料和SnAgCu焊料对比焊料厚度及焊料热导率不同对半导体激光器的影响。

3. 模拟结果分析

${R}_{th}=\frac{T-{T}_{0}}{P}$ (10)

Figure 2. Relationship between solder thickness and temperature

Figure 3. Laser temperature distribution cloud image

Table 2. Graphene layer parameter [10]

Figure 4. Heat flux vector diagram

Figure 5. Relationship between graphene layer thickness and chip temperature

Figure 6. Heat flux vector diagram of the improved structure

Figure 7. P-I Characteristics with different thermal resistance

4. 结论

NOTES

*通讯作者。

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