近年來，因為國際上環保意識抬頭，各國已禁止在電子產品中使用有毒物質，消費性產品中含鉛銲錫已被無鉛銲錫所取代。而隨著對於電子晶片高速運算與傳輸等的規格需求，半導體製程也朝著微縮化前進，相對地，因為試片製造的困難，所以在微觀尺度下無鉛銲錫其材料性質與可靠性仍然無法完全掌握。微電子封裝中電子構裝的小型化需要非常高密度的互聯與銲接，僅具有數十微米的支座高度，因此介金屬佔銲錫區的體積比對於形成可靠的接頭影響更為顯著，為了解無鉛銲錫在此尺度下的行為，本論文以實驗方法針對錫銀微接點試件藉由剪切負載來觀察材料的變形及損傷行為。實驗考慮的條件包含溫度、位移控制和負載峰值。實驗結果表現，無鉛銲錫微接點在剪切負載下表現明顯的塑性變形，而材料剪切強度隨著溫度的上升而下降，且相較於基於塊材試件之黏塑性參數所預測結果而言，實驗之飽和應力值較低。研究亦利用電子顯微鏡觀察出扇貝狀的介金屬層以及銲錫材料的塊狀錫元素與細紋的銀元素或錫銀合金之晶粒結構，在能量色散X-射線光譜確認其介金屬層為Cu6Sn5之組成。最後，利用有限元素法模擬不同溫度條件下之雙面搭接剪切實驗，並以黏塑性亞蘭德(Anand)模型作為無鉛銲錫微接點的本構方程，以發展銲錫材料在此微尺度的材料本構模型。

In this study, the constitutive behavior of Pb-free solder micro joint at various temperatures were investigated by using the double lap-shear experiment. From the scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectrometry analyses, it was observed that the ratio of solder to intermetallic compound (IMC) is about 3:1 and the scallop-shaped IMC is Cu6Sn5 in the Pb-free solder micro joint. It was also observed that the solder consists block grain of Sn and interdendritic grain of SnAg or Ag. The relationship between stress-strain constitutive behavior and various temperature was obtained from the double lap-shear experiment. The experiment results show that the Pb-free micro joint exhibits significant plastic deformation under shear loading, and the saturation stress decreases with increasing temperature. Numerical finite element (FE) simulations based on bulk-solder viscoplastic Anand model were then performed to consider the mechanical tests for evaluating the experimental response of the Pb-free micro solder joint. From the comparison between the numerical and experimental results, it was observed that the saturation stress of the micro joint is over-estimated when a bulk-solder viscoplastic model is used in the simulation. This inaccuracy may be attributed to the difference in the microstructure of the micro joint and the bulk solder. In the micro joint, the higher strength compound between the interdendritic zones in the solder is much less than in the bulk solder joint, and therefore, reduces the strength of the micro solder joint. Numerical model fitting was also applied to obtain the Anand viscoplastic model parameters for the micro-joint. The predictions of numerical model based on the fitting parameters were validated by the experimental evaluations of the micro joint under shear.

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