有限元素法模擬銲錫接點之熱應力

Abstract

有限元素分析軟體, MSC/NASTRAN, 以及其圖形處理器,MSC/XL,被使用來 研究在樑式試片中銲錫接點所遭受的熱應力。 本論文採用有限元素法是 因為這個方法能夠克服傳統解析法所遭遇到的難題且已被廣泛應用於電子 構裝的研究中。 在本論文裡, 首先探討了用於建立模型之元素大小及每 個節點自由度的效應。等溫和不等溫負載兩者皆被模擬並比較其結果。不 等溫負載是經由分析因功率消耗所造成的 溫度變化而得到的。 此外, 亦 探討銲錫接點之高度和面積對熱應變的影響。 最後, 考慮銲錫合金的塑 性及潛變形為而做了動態分析的模擬。 A general finite element analysis program, MSC/NASTRAN, and a graphical processor are employed to study thermal stresses of solder joints in a beam specimen. Finite element methods are used in this research because the methods can overcome difficulties encountered by conventional analytical methods. The effects of element mesh-size and degrees of freedom per grid point in the created model are studied. Both isothermal and nonisothermal loading conditions are simulated and results are compared. The nonisothermal load is acquired from a simulation of temperature distribution due to power dissipation . In addition, the joint-height and joint-area of solder alloy are studied for their effects on the sensitivity of thermal imposed strains. Also simulations with the assumptions that solder alloys behave as elastoplastic alloys and elastic-creep alloys are performed to study the dynamic response of the beam specimen subjected to thermal cycles.