Sheng Can, Wu Gai, Sun Xiang, Liu Sheng
School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China.
Polymers (Basel). 2021 Dec 28;14(1):103. doi: 10.3390/polym14010103.
In spite of a high market share of plastic IC packaging, there are still reliability issues, especially for the effects of moisture. The mechanism between moisture and epoxy polymer is still obscure. A multi-step cross-linking approach was used to mimic the cross-linking process between the DGEBA resin and JEFFAMINE-D230 agent. Based on the molecular dynamics method, the thermo-mechanical properties and microstructure of epoxy polymer were analyzed. In this paper, the degree of cross-linking ranged from 0% to 85.4% and the moisture concentration ranged from 0 wt.% to 12 wt.%. The hydrogen bonds were investigated in the moisture invaded epoxy polymer. Although most of the hydrogen bonds were related to water molecules, the hydrogen bonds between the inside of epoxy polymer were reduced only a little as the concentration of moisture increased. The diffusion coefficient of the water molecules was found to increase with the increase of moisture concentration. When the moisture concentration was larger than 12 wt.% or smaller than 1.6 wt.%, the diffusion coefficient was less affected by the epoxy polymer. In addition, the free volume and the thermal conductivity of the epoxy polymer were considered. It was found that the moisture could increase the thermal conductivity from 0.24 to 0.31 W/m/K, identifying a coupling relationship between moisture and thermal properties. Finally, the mechanical properties of epoxy polymer were analyzed by uniaxial tensile simulation. The COMPASS and DREIDING force fields were used during the uniaxial tensile simulation. A better result was achieved from the DREIDING force field compared with the experiment. The degree of cross-linking was positively correlated with mechanical properties. For the system with the largest degree of cross-linking of 85.4%, the Young's modulus was 2.134 ± 0.522 GPa and the yield strength was 0.081 ± 0.01 GPa. There were both plasticizing and anti-plasticizing effects when the water molecules entered the epoxy polymer. Both the Young's moduli and yield strength varied in a large range from 1.38 to 2.344 GPa and from 0.062 to 0.128 GPa, respectively.
尽管塑料集成电路封装具有较高的市场份额，但仍存在可靠性问题，尤其是在水分影响方面。水分与环氧聚合物之间的作用机制仍不明确。采用多步交联方法来模拟双酚A缩水甘油醚（DGEBA）树脂与聚醚胺-D230（JEFFAMINE-D230）试剂之间的交联过程。基于分子动力学方法，分析了环氧聚合物的热机械性能和微观结构。本文中，交联度范围为0%至85.4%，水分浓度范围为0 wt.%至12 wt.%。研究了水分侵入的环氧聚合物中的氢键。虽然大多数氢键与水分子有关，但随着水分浓度的增加，环氧聚合物内部的氢键仅略有减少。发现水分子的扩散系数随水分浓度的增加而增大。当水分浓度大于12 wt.%或小于1.6 wt.%时，扩散系数受环氧聚合物的影响较小。此外，还考虑了环氧聚合物的自由体积和热导率。发现水分可使热导率从0.24提高到0.31 W/m/K，表明水分与热性能之间存在耦合关系。最后，通过单轴拉伸模拟分析了环氧聚合物的力学性能。在单轴拉伸模拟过程中使用了COMPASS和DREIDING力场。与实验相比，DREIDING力场取得了更好的结果。交联度与力学性能呈正相关。对于交联度最大为85.4%的体系，杨氏模量为2.134±0.522 GPa，屈服强度为0.081±0.01 GPa。当水分子进入环氧聚合物时，既有增塑作用也有抗增塑作用。杨氏模量和屈服强度分别在1.38至2.344 GPa和0.062至0.128 GPa的较大范围内变化。
