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利用实验和Fick扩散方程模拟塑封材料对水的吸收过程,得到水汽在塑封材料中的扩散系数和饱和浓度. 塑封材料中的水分子存在于高分子链围成的微孔洞中,并与高分子聚合物以氢键相连. 当塑封材料中水汽浓度达到饱和时,在水分子进入的有效体积内,水汽的密度为标准状态下水蒸气密度的100倍,为液态水密度的8％,这表明在塑封材料中水分子以一种特殊的液态水形态存在. 在一定的水汽浓度下,在界面处的微孔洞中水气液两相共存. 在两相共存的微孔洞中由于水分子争夺高分子的氢键使高分子与芯片表面的二氧化硅层的结合减弱,逐步扩展形成可以观察到的分层.
Experiments and Fick diffusion equations were used to simulate the water absorption process of plastic materials, and the diffusion coefficient and saturation concentration of water vapor in the plastic materials were obtained.The water molecules in the plastic materials existed in the micropores surrounded by polymer chains, When the water vapor concentration in the plastic material reaches saturation, the water vapor density is 100 times the water vapor density of the standard state, which is 8% of the liquid water density, within the effective volume of water molecules entering, indicating that In plastic materials, water molecules exist in the form of a special liquid water. Under a certain water vapor concentration, the water-gas and liquid phases coexist in the micro-cavities at the interface. In the coexistence of two-phase micro-cavities, water molecules Competition for polymer hydrogen bonds to the polymer surface and the silicon dioxide layer with a combination of weakening, and gradually expanded to form a visible layer.