表面黏著技術(Surface Mount Technology)包括球腳格狀陣列(Ball Grid Array)以及覆晶技術(Flip Chip Technology)已經廣泛被使用在現今的微電子構裝技術中。在表面黏著技術中最常見的問題常是在工作環境下，因為不同材料間的熱膨脹係數差異，特別是晶片端(chip)與板端(board)的差異造成熱應力導致翹曲(warpage), 材料分層(delamination) 以及塑性應變累積在彈性係數較小的焊錫球內，最終造成裂縫並且破壞。封裝材料本身的強度以及封裝的架構與製程都是影響熱應力問題的關鍵。
在本研究中，利用鎳鈦記憶合金來當作覆晶下金屬塊結合在焊錫球接點上。鎳鈦記憶合金與有兩種獨特的性質，一是形狀記憶效果(shape memory effect)，在室溫附近的麻田相變化可使得鎳鈦合金在低溫時所受到的變形因相變化而回復，可達約35%的形變回復量。二是擬彈性質(superelasticity),在沃斯田相的鎳鈦記憶合金在承受一超過極限值的應力時，會有應力引發麻田相變化(stress induced martensitic transformation)，其可承受應變大幅增加，相當於提供合金額外的彈性質。本研究的目標在於探討記憶合金應用在焊錫球接點上對於可靠度的影響。
利用物理氣相蒸鍍的方式，多層金屬層包括鎳鈦記憶合金層可以被製作出來。利用物理氣相蒸鍍方式所製備的鎳鈦記憶合金經由X光繞射分析(X-ray diffraction)，熱差分析(differential scanning calorimetry) 與穿透式電子顯微鏡(transmission electron microscope)驗證鎳鈦記憶合金相的存在。此外，由於利用物理氣相蒸鍍方式製備的鎳鈦記憶合金為非晶(amorphous)結構，必須經過後退火過程使其轉換成結晶型態。然而高退火溫度會造成製程上的困難，故在本研究中嘗試添加第三元素銅來降低結晶溫度。
利用物理氣相蒸鍍方式製備的記憶合金覆晶下金屬塊與一般的鎳銅金屬塊，利用黃光製程製備聚亞醯胺(polyimide)保護層以及固定大小焊點(pad)，在利用錫銀銅焊料以及網版印刷方式製備錫球接點。製備好的焊球接點在一次回焊與印刷電路板接合以製備成品。製備好的成品在經過不同次數後的熱震盪(thermal shock)、熱循環(thermal cycling)以及彎曲測試(bend test) 後，觀察介面接點以及焊錫球的推球與拉球強度變化，探討記憶合金對可靠度的影響。
除了實驗部分以外，也利用有限元素分析以及數學上的三層結構應力分析方式來分析多層材料間因不同材料性質在溫度循環下所造成的熱應力以及應變的大小與分佈，探討在錫球與晶片間的不同金屬介層，以及介層不同厚度對於應力應變的影響。

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