芯片互连层及封装基板对大功率LED器件光热性能的影响
发布时间：2018-10-25 06:29
【摘要】：LED具有尺寸小、亮度高、节能环保、寿命长、效率高等优点,因此被广泛应用于交通信号灯、汽车后灯、液晶显示、夜景照明及普通照明等,白光LED是继白炽灯和荧光灯照明的新一代照明光源。但LED电光转换效率较低,多余的电能在芯片内转化为热能,若不能及时将热量导出,会导致芯片结温升高,从而影响LED器件散热及可靠性。LED器件散热问题成为制约其产业发展的主要瓶颈,因此需要优化热设计降低LED器件热阻即提高LED散热性能。互连材料及互连层空洞率(互连层空洞体积与互连层体积之比)对大功率LED散热有着重要影响,大功率LED封装基板对其扩散热阻有一定的影响,因此互连材料、互连层空洞率及封装基板是大功率LED热设计中的关键。首先采用T3ster热阻测试仪和ANSYS热学仿真对LED器件及模型进行热学分析,以三种互连材料(金锡、锡膏及银胶)对LED器件热阻及芯片结温的影响为例,分析了互连材料的热导率及厚度对LED器件热学性能的影响。实验结果表明:互连层热阻约占LED器件总热阻的1/3,是影响LED结温的主要因素之一;金锡互连质量最好,其互连层热阻最小;金锡共晶互连封装器件互连层厚度最小,厚度越小对HP-LED散热越有利。热学模拟结果表明:互连材料热导率升高到20 W/m K时,再提高互连材料热导率对HP-LED散热性能的影响不再显著;互连层与芯片和基板的有效接触面率从100%减小到10%,LED结温升高了8.7%。互连材料的热导率、厚度及互连层与芯片和基板的有效接触面积均会影响LED芯片的结温,因此在LED器件互连的设计中,需综合考虑以上三个关键参数,以实现散热性能最佳化。其次研究了互连层空洞率对大功率LED的光学、热学及电学性能的影响,通过实验及仿真数据分析互连层空洞率对大功率LED的光学、热学及电学性能的影响,实验结果表明:共晶压力从0 N增加到2 N,互连层空洞率从62.45%减小到16.53%,互连层热阻(由互连材料及互连层空洞共同产生的热阻)减小了82.7%;光通量随着互连层热阻的减小而增大,光通量增大了6.87%。有限元模拟结果表明:互连层空洞对LED芯片的热应力及热应变分布有较大影响,仿真结果发现互连层30%的空洞率使LED芯片的热应力及热应变分别增加了49.87%和50%;互连层空洞对有源层的电场强度及芯片最大电流密度均有较大影响,空洞使LED芯片最大电流密度及电场强度分别增大了161.06%和37.15%。最后研究了大功率LED封装模块扩散热阻的影响因素。运用T3ster热阻测试仪、有限元仿真及扩散热阻计算公式对LED封装模块进行热学分析,对于LED单芯片扩散热阻研究结果表明:①扩散热阻在LED封装模块热阻中占较大比重,约占60.49%;②热源与基板之间的接触面率是扩散热阻的主要影响因素,接触面率增大有利于减小扩散热阻;③扩散热阻随着基板厚度的增大而先减小后变大,存在最佳基板厚度使得扩散热阻最小;④芯片与基板的中心距对LED模块的扩散热阻及芯片结温有着重要影响。对于LED多芯片封装模型,运用有限元仿真LED多芯片温度场分布,建立基板到空气热阻模型树,提出了直接求解多芯片热源扩散热阻方法,模拟不同热源位置对温度场分布的影响。研究结果表明:①对比直接法与间接法求解多芯片热源扩散热阻,结果验证了直接法的准确性;②运用MATLAB求解了多芯片模块温度场结果,验证了有限元仿真多芯片热源温度场分布的准确性;③分析不同基板尺寸对扩散热阻和总热阻的影响,结果表明随着基板面积的增大,扩散热阻逐渐升高,而总热阻却逐渐下降。因此在基板尺寸设计时,需要综合考虑导体热阻、空气对流热阻与扩散热阻,使总热阻达到最佳值。
[Abstract]:The LED has the advantages of small size, high brightness, energy conservation, environmental protection, long service life, high efficiency and the like, and is widely applied to traffic signal lamps, automobile rear lights, liquid crystal display, night scene lighting and common lighting, and the like, and the white light LED is a new generation of illumination light sources which follow incandescent lamp and fluorescent lamp illumination. but the LED electro-optical conversion efficiency is low, the excess electric energy is converted into thermal energy in the chip, and if the heat can not be exported in time, the chip junction temperature is increased, thereby influencing the heat dissipation and the reliability of the LED device. LED device heat dissipation is the main bottleneck restricting its industrial development. Therefore, it is necessary to optimize the thermal design to reduce the thermal resistance of LED devices, that is, to improve the heat dissipation performance of LED devices. Interconnection material and interconnection layer void ratio (ratio of cavity volume of interconnect layer and interconnection layer volume) have an important effect on the heat dissipation of high-power LED, and the high-power LED package substrate has a certain influence on the diffusion resistance of the high-power LED, so that the interconnection material, The cavity rate of the interconnect layer and the package substrate are the key in high power LED thermal design. In this paper, the thermal analysis of LED devices and models was carried out using T3ster thermal resistance tester and ANSYS thermal simulation. The effects of thermal conductivity and thickness on the thermal properties of LED devices were analyzed by using three kinds of interconnect materials (gold tin, tin paste and silver glue) as examples. The experimental results show that the thermal resistance of the interconnect layer accounts for about 1/ 3 of the total thermal resistance of the LED device, which is one of the main factors affecting the junction temperature of the LED. The thermal simulation results show that when the thermal conductivity of the interconnect material rises to 20 W/ m K, the effect of increasing the thermal conductivity of the interconnect material on the heat dissipation performance of HP-LED is no longer significant; the effective contact surface rate of the interconnect layer and the chip and the substrate is reduced from 100% to 10%, and the temperature of the LED junction is increased by 8. 7%. The thermal conductivity, thickness and the effective contact area of the interconnection layer and the chip and the substrate can affect the junction temperature of the LED chip, therefore, in the design of the LED device interconnection, the above three key parameters need to be comprehensively considered, so as to realize the best heat dissipation performance. Secondly, the influence of the cavity rate on the optical, thermal and electrical properties of the high power LED is studied, and the influence of the cavity rate on the optical, thermal and electrical properties of the high power LED is analyzed through experiments and simulation data. The experimental results show that the eutectic pressure increases from 0 N to 2N, The cavity rate of interconnect layer is reduced from 62. 45% to 16.53%, and the thermal resistance of interconnect layer (thermal resistance generated by interconnect material and interconnect layer cavity) is reduced by 82.7%; the luminous flux increases with the decrease of thermal resistance of interconnect layer and the luminous flux increases by 6.87%. The results of the finite element simulation show that the thermal stress and thermal strain distribution of the LED chip are affected by the void ratio of the interconnect layer cavity, and the thermal stress and thermal strain of the LED chip are increased by 49. 87% and 50%, respectively. The electric field intensity of the active layer and the maximum current density of the chip are greatly influenced by the cavity of the interconnection layer, and the maximum current density and the electric field strength of the LED chip are increased by 161. 06% and 37.15% respectively. Finally, the influence factors of the diffusion thermal resistance of the high power LED package module were studied. The thermal analysis of LED package module using T3ster thermal resistance tester, finite element simulation and diffusion thermal resistance calculation formula was carried out. The results show that the thermal resistance of LED single chip is about 60. 49% of the thermal resistance of LED package module. the contact surface ratio between the heat source and the substrate is the main influencing factor of the diffusion thermal resistance, the contact surface rate is increased, and the diffusion thermal resistance is reduced; The center distance between the LED chip and the substrate has an important influence on the diffusion thermal resistance and the chip junction temperature of the LED module. For LED multi-chip package model, the temperature field distribution of LED multi-chip is simulated by finite element simulation, and a substrate-to-air thermal resistance model tree is built, and the influence of different heat source positions on temperature field distribution is simulated by directly solving the multi-chip heat source diffusion thermal resistance method. The results show that direct method and indirect method are used to solve the diffusion thermal resistance of multi-chip heat source, and the accuracy of direct method is verified. The results of temperature field of multi-chip module are solved by using MATLAB, and the accuracy of temperature field distribution of multi-chip heat source is verified by finite element method. The effect of different substrate sizes on diffusion thermal resistance and total thermal resistance is analyzed. The results show that with the increase of the area of the substrate, the diffusion thermal resistance increases gradually, but the total thermal resistance gradually decreases. Therefore, when the size of the substrate is designed, it is necessary to comprehensively consider the thermal resistance of the conductor, the convection thermal resistance of the air and the diffusion thermal resistance, so that the total thermal resistance reaches the optimum value.
【学位授予单位】：上海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8
本文编号：2292900
[Abstract]:The LED has the advantages of small size, high brightness, energy conservation, environmental protection, long service life, high efficiency and the like, and is widely applied to traffic signal lamps, automobile rear lights, liquid crystal display, night scene lighting and common lighting, and the like, and the white light LED is a new generation of illumination light sources which follow incandescent lamp and fluorescent lamp illumination. but the LED electro-optical conversion efficiency is low, the excess electric energy is converted into thermal energy in the chip, and if the heat can not be exported in time, the chip junction temperature is increased, thereby influencing the heat dissipation and the reliability of the LED device. LED device heat dissipation is the main bottleneck restricting its industrial development. Therefore, it is necessary to optimize the thermal design to reduce the thermal resistance of LED devices, that is, to improve the heat dissipation performance of LED devices. Interconnection material and interconnection layer void ratio (ratio of cavity volume of interconnect layer and interconnection layer volume) have an important effect on the heat dissipation of high-power LED, and the high-power LED package substrate has a certain influence on the diffusion resistance of the high-power LED, so that the interconnection material, The cavity rate of the interconnect layer and the package substrate are the key in high power LED thermal design. In this paper, the thermal analysis of LED devices and models was carried out using T3ster thermal resistance tester and ANSYS thermal simulation. The effects of thermal conductivity and thickness on the thermal properties of LED devices were analyzed by using three kinds of interconnect materials (gold tin, tin paste and silver glue) as examples. The experimental results show that the thermal resistance of the interconnect layer accounts for about 1/ 3 of the total thermal resistance of the LED device, which is one of the main factors affecting the junction temperature of the LED. The thermal simulation results show that when the thermal conductivity of the interconnect material rises to 20 W/ m K, the effect of increasing the thermal conductivity of the interconnect material on the heat dissipation performance of HP-LED is no longer significant; the effective contact surface rate of the interconnect layer and the chip and the substrate is reduced from 100% to 10%, and the temperature of the LED junction is increased by 8. 7%. The thermal conductivity, thickness and the effective contact area of the interconnection layer and the chip and the substrate can affect the junction temperature of the LED chip, therefore, in the design of the LED device interconnection, the above three key parameters need to be comprehensively considered, so as to realize the best heat dissipation performance. Secondly, the influence of the cavity rate on the optical, thermal and electrical properties of the high power LED is studied, and the influence of the cavity rate on the optical, thermal and electrical properties of the high power LED is analyzed through experiments and simulation data. The experimental results show that the eutectic pressure increases from 0 N to 2N, The cavity rate of interconnect layer is reduced from 62. 45% to 16.53%, and the thermal resistance of interconnect layer (thermal resistance generated by interconnect material and interconnect layer cavity) is reduced by 82.7%; the luminous flux increases with the decrease of thermal resistance of interconnect layer and the luminous flux increases by 6.87%. The results of the finite element simulation show that the thermal stress and thermal strain distribution of the LED chip are affected by the void ratio of the interconnect layer cavity, and the thermal stress and thermal strain of the LED chip are increased by 49. 87% and 50%, respectively. The electric field intensity of the active layer and the maximum current density of the chip are greatly influenced by the cavity of the interconnection layer, and the maximum current density and the electric field strength of the LED chip are increased by 161. 06% and 37.15% respectively. Finally, the influence factors of the diffusion thermal resistance of the high power LED package module were studied. The thermal analysis of LED package module using T3ster thermal resistance tester, finite element simulation and diffusion thermal resistance calculation formula was carried out. The results show that the thermal resistance of LED single chip is about 60. 49% of the thermal resistance of LED package module. the contact surface ratio between the heat source and the substrate is the main influencing factor of the diffusion thermal resistance, the contact surface rate is increased, and the diffusion thermal resistance is reduced; The center distance between the LED chip and the substrate has an important influence on the diffusion thermal resistance and the chip junction temperature of the LED module. For LED multi-chip package model, the temperature field distribution of LED multi-chip is simulated by finite element simulation, and a substrate-to-air thermal resistance model tree is built, and the influence of different heat source positions on temperature field distribution is simulated by directly solving the multi-chip heat source diffusion thermal resistance method. The results show that direct method and indirect method are used to solve the diffusion thermal resistance of multi-chip heat source, and the accuracy of direct method is verified. The results of temperature field of multi-chip module are solved by using MATLAB, and the accuracy of temperature field distribution of multi-chip heat source is verified by finite element method. The effect of different substrate sizes on diffusion thermal resistance and total thermal resistance is analyzed. The results show that with the increase of the area of the substrate, the diffusion thermal resistance increases gradually, but the total thermal resistance gradually decreases. Therefore, when the size of the substrate is designed, it is necessary to comprehensively consider the thermal resistance of the conductor, the convection thermal resistance of the air and the diffusion thermal resistance, so that the total thermal resistance reaches the optimum value.
【学位授予单位】：上海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8
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相关期刊论文 前2条
1 苗洪利,王进,王晶,陈静波,孟继武;LED白光照明光源的研制[J];光电子·激光;2004年06期
2 许敏;;结合面接触热阻模型研究与应用[J];机械制造;2006年01期
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