The theory of viscoplasticity is applied to analyze the tendency of stress intensity factor and the difference of the life-cycle between the above models is discussed in detail.

• 因此本文在两种尺寸之构装模型上，分别采用含铅材料及未来势必使用之无铅材料锡球，以黏塑性质理论加以分析，比较各裂缝应力强度因子之趋势变化，以探讨上述模型存有裂缝时之寿命差异。