同步輻射X光量測錫膜應力對錫晶鬚生長動力學之影響;Synchrotron Radiation X-Ray Measurement of Residual Stress in Sn Films and the Effect on Kinetic Analysis of Sn Whisker Growth

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題名:	同步輻射X光量測錫膜應力對錫晶鬚生長動力學之影響;Synchrotron Radiation X-Ray Measurement of Residual Stress in Sn Films and the Effect on Kinetic Analysis of Sn Whisker Growth
作者:	陳灝,;Chen,Hao
貢獻者:	化學工程與材料工程學系
關鍵詞:	錫晶鬚;微結構;殘留應力;同步輻射X光;Sn whisker;Microstructure;Residual stress;Synchrotron radiation X-ray
日期:	2016-05-19
上傳時間:	2016-06-04 12:24:12 (UTC+8)
出版者:	國立中央大學
摘要:	自發性錫晶鬚之生成是危害電子元件可靠度的主因之一，電子構裝產業中常以錫銅兩種材料為主體，然而在室溫下，當錫與銅接觸時即反應生成介金屬化合物，並對錫膜內部產生一壓應力，此應力便是造成自發錫晶鬚生長之主要驅動力。近年來伴隨著電子元件趨向微型化，且高可靠度之電子元件亦被廣泛應用，無鉛銲錫引發之錫晶鬚危害也日趨嚴重，因此瞭解錫晶鬚生長機制便是一重要課題。但由於錫晶鬚生長的難以預測性，加劇了研究之困難，為了能更深入研究錫晶鬚之生長機制，本實驗利用微影技術方式於錫薄膜表面製造規則陣列圖形，創造出規則的人工弱點，並藉由此法控制錫晶鬚生長位置。本實驗亦改變錫膜之微結構，欲探究錫膜微結構對於錫晶鬚生長之關係，藉由定量分析量測不同微結構之錫膜中錫晶鬚的生長模式。本研究觀察到錫晶鬚直徑與錫晶粒之相依性，驗證錫晶鬚之直徑將被錫膜晶粒所控制，研究結果直接證實錫膜的平均晶粒及厚度皆可對錫晶鬚之生長行為造成影響，其中錫膜厚度影響錫晶鬚之生長更勝於錫膜平均晶粒之影響。錫晶鬚自發性之生成包含了應力的產生與釋放，此次研究進一步利用同步輻射光源量測錫膜之殘留應力，觀測微結構對於殘留應力釋放之影響，並且連結錫晶鬚之孕核期與薄膜之殘留應力。本研究利用熱力學之理論方式，探討錫晶鬚生長行為與各式微結構錫膜之關係式。由本論文之結果可知，增加錫膜厚度以及晶粒大小皆可降低錫晶鬚之生成，並延緩錫晶鬚之生長速率，工業界可藉由此方式，降低因錫晶鬚造成短路之可能性，如此便可提升元件之可靠度。同時可利用本論文所提出之數學模型，簡單預測錫晶鬚在不同錫膜微結構下之關係，調整最符合業界經濟效益之元件鍍膜設計，提供業界於設計元件及提升可靠度之一參考。 ;Spontaneous Sn whisker growth is one of the most serious reliability problems for electronic devices. Sn and Cu are commonly used in electronic packaging, and they easily form intermetallic compounds (Cu6Sn5) at room temperature, inducing compressive stress, which is the main force that drives the spontaneous growth of Sn whiskers from Sn films. The electronic product tends to be smaller and thinner than the preceding design, and the demands for high reliability devices are increasing. The risk of Sn whiskers increases with each new design iteration. Manufacturers must understand the growth mechanisms of Sn whiskers to minimize the problems, but the unpredictability of Sn whisker growth caused difficulties for research. To effectively discuss the growth mechanisms of Sn whiskers, a lithography process was used to control the positions of Sn whiskers by creating arrays of weak spots on Sn film surfaces. This study discusses how Sn film microstructures affect the kinetics of spontaneous Sn whisker growth and qualitatively analyzes Sn whiskers with various microstructures. The result indicates a strong correlation between the whisker diameter and grain size of the films. The whisker diameters were confined depended on the sizes of the Sn grains. The results directly evidenced that both the thickness and grain size of Sn films can influence the growth of Sn whiskers. Additionally, thickness has a greater effect on whisker growth than grain size does. Since Sn whisker growth is a spontaneous phenomenon that combines continuous processes of stress generation and relaxation, biaxial stress in the films was measured using synchrotron radiation X-ray. The stress evolution during annealing was correlated with the growth kinetics. An incubation period was observed, during which the compressive stress in the films built up and the whiskers nucleated. From the thermodynamic relationship between the growth kinetics of the Sn whiskers and the microstructures of the films, an equation was formulated to predict the growth of the Sn whiskers from various microstructures of the films. According to the results, increasing the thickness and grain size of Sn films would inhibit the growth rates of whiskers and suppress the formation of whiskers. Through this method, the electronic packaging industry can enhance device reliability.
顯示於類別:	[化學工程與材料工程研究所] 博碩士論文

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