Pusat Pengajian Kejuruteraan Mekanikal - Tesis

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Browsing Pusat Pengajian Kejuruteraan Mekanikal - Tesis by Author "Elwin Heng, Chia Jie"

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    Moisture diffusion during solder reflow processes of electronic packages
    (2022-01-01)
    Elwin Heng, Chia Jie
    The modern electronic packages has evolved and become so complex while the size has continued to shrink. packages continues to shrink. As a result, modern days electronic has become complex in manufacturing yield and reliability defect has become a huge concern. Moisture induced quality and reliability defect are not new to electronics industries. But the complexity of the modern days packages has caused moisture induced defect to become a huge concern. Hydroscopic materials in electronic packages are capable to absorb moisture upon exposure to environment throughout storage, manufacturing process and transport phase. Although moisture is supposed to be desorb when going through high temperature reflow process, but the presences of hydrophobic material in the structure could possibly obstruct and hinder the moisture desorption, causing residue moisture to continue reside in electronic packages. The internal moisture will develop high internal vapour pressure when going through high temperature loading. This vapour pressure can cause void, delamination, cracking to electronic packages internal structure, which can be detrimental to electronic packages. The moisture diffusion is very difficult to be analyse as electronic packages often made up from multiple components with different material properties, causing the moisture diffusion very difficult to be modelled can calculated. This paper will utilize Direct Concentration Approach (DCA) to model the moisture diffusion accurately to analyse the effect from moisture diffusion. Aside from the pressure develop from moisture, the high temperature subjected to electronic packages will also causing thermal stress. The typical electronic package with hydrophobic material could obstruct moisture desorption and causing moisture residue found to be 36% higher in vapour pressure compared to bi-material model, going beyond saturate vapour into superheated vapour or compressed liquid, which expose electronic package to higher pressure. The maximum Von-Misses syress induced by moisture significantly increase on package with hydrophobic material by 115% compared to model with hydrophilic material. With the use of Direct Concentration Approach, the effect of moisture diffusion and coupling with thermal stress in the aspect of Fluid Structural Interaction will be able to be studied.