QFN構裝體是由許多材料所組成，當受到溫度循環負載，由於各元件材料熱膨脹係數的不一致而導致構裝體結構變形，進而造成錫球產生疲勞破壞，因此本文針對QFN構裝體為對象，考慮兩種錫球材料與不同錫球高度，受到溫度循環變化的負載，探討錫球疲勞可靠度的影響。其分析模型係採用ANSYS有限元素分析軟體先建構1/4構裝體，並以亞蘭德模式描述錫球黏塑性行為模式，其它材料則視為線彈性。而溫度循環之變化範圍為-40℃~125℃，每循環的高低溫持平時間各為5分鐘、升降溫時間各為10分鐘；每循環為30分鐘。然後再計算最外側錫球（導線架與基板間）之變形、應力與應變及遲滯曲線等機械行為之變化情形，並將等效應變範圍值代入Coffin-Manson計算公式中，以預估錫球之疲勞壽命。

QFN package consists of various components. When the package suffers a temperature cycling load as the different coefficients of thermal expansion（CTE）of those components, it will tend to deform and lead to fatigue of solder joint. For this reason, the effects on fatigue life of QFN package when it is under temperature cycling load by means of two different kinds of solder at different altitudes will have a detail discussion in this paper. Applying finite element analysis software ANSYS for building a 1/4 model. To describe the material behavior of solder, Anand’s model were used in viscoplastic analysis respectively, but other components are assumed to be linear elastic. The temperature fluctuating cycle is between -40℃and 125℃. The package dwells at high temperature or low temperature for 5 minutes and is heated from room temperature to 125℃ in 10 minutes and cooled down from 125℃to -40℃ in 10 minutes. Each cycle is 30 minutes. This paper computed the deformation, stress, strain and hysterisis curve of the outermost solder joint (between leadframe and PCB). The equivalent strain range is substituted
into Coffin-Mansion formula to estimate the fatigue life of solder joint.

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