| Summary: | 碩士 === 國立虎尾科技大學 === 電子工程系碩士班 === 103 === In this study, Aluminum-Germanium and Indium-Tin metal structural films were prepared by vacuum thermal evaporation on the glass substrate. In order to explore the effect of different temperatures of hot tin plating layers with different thicknesses, the transient liquid bonding technology and the thermal cycles were performed, the thermal cycling characteristics of the metal joints were relative to the shear strength. After the thermo-compression bounding, the SEM, EDS and XRD analysis of the samples were carried out and by inspection the AlGe/Sn interfaces and AlGe/InSn one. Then we observed the impact of stress, surface morphology, microstructure, and composition ratios of the crystal phases.
According to the shear stress statistics, at 280 oC the average shear strength was found to be larger than 12 kg/cm2 while the heat cycles were applied from one to three cycles. When the bounding temperature was reduced to 260 oC or even as low as 240 oC, it was found that the shear stress intensities rise with increasing the number of thermal cycles. At the 2~3μm thickness of tin plating, the number of thermal cycles was increased to four or more while the shear stress has reached the value of 12 kg/cm2 which is the limit of highest value in our shear tester. However, for the 1μm thickness of tin plating, the number of thermal cycles needs five thermal cycles to reach the maximum stress of 12 kg/cm2.
The fracture surface of samples was examined by SEM and EDS analysis. One sample with a 3 μm-thick Tin plated layer was applied three thermal cycles at high temperature of 280 oC. Also, the other one with 1μm-thick Tin plated layer was applied five thermal cycles at low temperature of 240 oC. Both these two samples have very strong bounding strength and even are torn off the substrate.
From the XRD analysis, under different bounding temperatures, different thickness of tin plated layer and thermal cycles, the samples with the increase in the number of heat cycles are the In0.05Sn0.95 α phase(200), (220), (211), In0.1818Sn0.8182 β phase (100), (101), and In0.75Sn0.25 γ phase (220). These co-crystal phases and the relatives were enhanced and got stronger when their shear stress was increased. Here the In0.05Sn0.95 α phase was gradually obvious and enhanced, The In0.1818Sn0.8182 β phase and the In0.75Sn0.25 γ phase were gradually weakened or even disappeared. It is attributed that the β and γ phase might have a transition into α phase.
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