隨著電子產品的尺寸逐漸縮小，流經電子元件的電流密度大幅提升，使得電遷移(Electromigration)成為影響整體封裝結構可靠度的重要議題之一，因此許多研究紛紛投入研究電流對銲錫接點的影響。材料微結構的變化決定材料於應用上的表現，故本研究以材料的觀點出發，探討Sn-Ag銲錫合金於通電狀態下的行為。本研究將Sn-3.5wt%Ag銲錫薄帶施以5.0×103~7.0×103A/cm2之電流，同時進行臨場(in situ)同步輻射X光繞射實驗(Synchrotron X-ray diffraction)，利用X光繞射圖譜分析Sn基地相及Ag3Sn之結晶性質，結果顯示兩者之結晶性質於通電中下降，晶面被破壞的程度與電流密度和結晶面性質相關。由高解析TEM影像可觀察到晶面受電子擾動的情形，本研究依破壞的程度大致將通電中的微結構分成三種類型，並以電致擾動過渡期(Transition stage)及偽非晶質(Pseudo amorphous)組織解釋X光繞射峰下降以及Sn基地相晶界消失的行為。

The ever decreasing device dimension and thus the increasing current density render electromigration an important concern in the reliability of solder joint. Investigations have been focused on the influence of current stressing on the performance of the solder joint. From materials perspective, the microstructural variation of the solder is expected to govern the joint performance. This study investigated the effect of current stressing on the crystalline structure of Sn-3.5wt%Ag solder alloy. The in situ synchrotron X-ray diffraction analysis was conducted for the Sn-3.5wt%Ag strips under current stressing at 5.0×103~7.0×103A/cm2. The crystallinity of Sn matrix and Ag3Sn compound were analyzed with X-ray spectrum. The results indicated that the crystalline behavior of Sn matrix and Ag3Sn was disrupted by electron flow. The influence of the electrical current depends on the crystalline plane and current density as well. The HRTEM investigation indicated that the crystal plane of Sn matrix and Ag3Sn was damaged by the electron flow, which resulted in three different types of microstructure. The degradation of crystallinity in XRD results and the disappearance of grain boundaries of Sn matrix was caused by the transition stage of electro-disruption and the pseudo amorphous structure in the current stressed specimen.

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