Mechanism of Moisture Diffusion, Hygroscopic Swelling, and Adhesion Degradation in Epoxy Molding Compounds
Mechanism of Moisture Diffusion, Hygroscopic Swelling, and Adhesion Degradation in Epoxy Molding Compounds
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DOI：
10.1007/978-1-4419-5719-1_2
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发表时间：
2010-01-01
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影响因子：
--
通讯作者：
Michel, B.
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文献类型：
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作者：
Shirangi, M. H.;Michel, B.
环氧模塑化合物（EMCs）被广泛用作封装材料，用于保护塑料封装微电路（PEM）的半导体芯片免受恶劣环境和机械力（例如冲击和压力）的影响。由于PEM在其储存和使用寿命期间通常暴露于潮湿条件下，它们吸收水分，这导致许多可靠性问题，例如在焊料回流过程中的爆米花开裂和界面分层。本章提出了一个全面的调查机制的水分扩散电磁兼容。在吸收，解吸和再吸附的各种EMC样品的水分扩散试验的结果。重量分析结果表明，在EMC中的水分扩散的非菲克行为。发现这种非菲克行为通过在烘烤这些塑料部件时引起一些残留水分含量而引起不可逆效应。重量水分扩散结果可以与水分引起的吸湿膨胀和粘附损失相关。采用大体积EMC样品和双材料梁研究了EMC的吸湿膨胀及其可逆性。此外，使用断裂力学方法研究了水分对EMC/Cu界面结合力的影响。可以观察到水分扩散时粘附力损失的两种机制。由于少量水分含量而导致的一些粘附损失可以通过适当的退火来恢复。然而，在潮湿条件下长期储存时，其中非菲克行为的第二相在界面处被激活，在烘烤样品后没有粘附损失可以恢复。
Epoxy molding compounds (EMCs) are widely used as encapsulation materials for protecting the semiconductor chips of plastic encapsulated microcircuits (PEMs) against harsh environments and mechanical forces such as impact and pressure. Since PEMs are usually exposed to humid conditions during their storage and service life, they absorb moisture, which causes many reliability problems such as popcorn cracking and interfacial delamination during the solder reflow process. This chapter presents a comprehensive investigation of the mechanism of moisture diffusion in EMCs. The results from moisture diffusion tests during absorption, desorption, and re-sorption of various EMC samples are presented. The gravimetric results showed a non-Fickian behavior of the moisture diffusion in the EMCs. This non-Fickian behavior was found to induce a non-reversible effect by causing some residual moisture content upon baking these plastic parts. The gravimetric moisture diffusion results can be correlated to moisture-induced hygroscopic swelling and adhesion loss. Hygroscopic swelling of EMC and its reversibility was investigated using both bulk EMC samples and bi-material beams. Moreover, the effect of moisture on the adhesion of EMC/Cu interface was studied using a fracture mechanics approach. Two mechanisms of adhesion loss upon moisture diffusion can be observed. Some of the adhesion loss due to small amount of moisture content may be recovered via a proper annealing. However, upon long-term storage in humid conditions, where the second phase of non-Fickian behavior is activated at the interface, none of the adhesion loss can be recovered after baking the samples.