TFT-LCD面板雷射銲接金屬框架機械性質研究

Abstract

本論文以不同的Nd：YAG雷射參數，研究0.6mm鍍鋅鋼板之(Thin Film Transistor Liquid Crystal Display，TFT-LCD)鐵框架在不同的雷射功率與雷射聚焦點深度條件下，其銲道之機械性質與顯微結構。 拉伸試驗結果顯示：雷射功率1100W、1050W、1000W、及雷射聚焦點深度+2、+1.5、+1、0等7組試片，可得到較佳的銲道強度。由金相試驗的結果可得知：不同銲接參數的鍍鋅鋼板其顯微組織是肥粒鐵(ferrite)為母材微結構組織。為鍍鋅鋼板經雷射銲接後的銲道組織，其顯微組織也是肥粒鐵，主要在於受雷射銲接過程中局部熱的影響，致使材料受高溫產生熔融而且無凝固，其晶粒成長，依序為FZ>HAZ>BM，晶粒的大小會影響銲件的硬度、抗拉強度…等機械性質。微硬度試驗結果顯示：銲接後之銲道硬度會大於原先母材值。此外，由試驗可觀察到，銲道中央位置之硬度值較高，其原因是中央位置的冷卻速度較快。相對的，熱影響區域因冷卻速度較慢，所以硬度值較低。從硬度值曲線的分佈情形得知，雷射銲接試片的銲道非常小，寬度在1㎜以下，熱影響區的影響範圍也很小。

In this thesis, the various laser parameters –Nd : YAG– that are the power and the focal depth of laser are investigated into the mechanism and microstructure properties of the welding trajectory in the frame of galvanized steel plate. Firstly, according to the tensile experiment result, there could be seven conditions, which are the 1100(w), 1050(w), and 1000(w) of laser power and the laser focal depth such as 2, 1.5, 1, and 0 obtained the better strength of weld. Secondly, according to metallographic test result, the microstructure organization of galvanized steel plate in the different parameters of weld and base metal material are both same, as Ferrite. In the laser welding process, the frame of galvanized steel plate was only welded partly in the highly temperature condition and not solidified. This crystal size of welding would affect its hardness, anti-tensile strength, and mechanical property. Finally, regarding the micro-hardness test result, the center position of weld trajectory after welding, due to its cooling rate is faster than other positions, therefore, its hardness is so too. On the other hand, relative to its center, the hardness of other positions is more weakly. According to the figure of hardness distribution curve, we found that the size of weld trajectory on the experimental specimens is quite small and its width is below one millimeter.