QFN封装焊点可靠性的有限元分析  

Finite element analysis on soldered joint reliability of QFN device

作　　者：姬峰[1] 薛松柏[1] 张亮 王慧[1] 

机构地区：[1]南京航空航天大学材料科学与技术学院,南京210016

出　　处：《焊接学报》2009年第10期57-60,共4页Transactions of The China Welding Institution

基　　金：江苏省普通高校研究生科技创新计划资助项目(CX07B087Z);2006年江苏省"六大人才高峰"资助项目(06-E-020)

摘　　要：建立了QFN(quad flat non-leaded)的1/4模型,用Anand模型构建了Sn3.0Ag0.5Cu的本构方程,并比较了不同焊点形态时QFN的可靠性.结果表明,在温度循环载荷下,QFN器件应力的最大值位于拐角处的焊点的上表面处,且其应力值变化具有周期性和叠加性;无缩回设计的引脚比有缩回设计的引脚具有更好的可靠性,但对于无缩回设计的引脚,其焊脚高度和焊点长度对其塑性功的累积无明显影响;钎料厚度对焊点塑性功的累积有明显影响,焊点的单位体积塑性功与钎料厚度成反比;中央散热焊盘的焊接面积对焊点塑性功的累积有一定影响,在QFN的焊接过程中可以适当增加其焊接面积.Quarter models of QFN(quad flat non-leaded) were set-up by means of ANSYS software,Anand model was used to establish the constitutive equation of Sn3.0Ag0.5Cu solder,and the reliability of QFN with different solder joint shape was presented.The results indicate that the maximum value of stress is at the package corner,which value change is cyclical and additive.The solder joint reliability of leads with pullback design is poorer than that of the leads non-pullback design that cannot influence the value of plastic work caused by the solder fillet length and land length significantly.The effect of solder thickness is very obviously,and the average plastic work is inversely proportional to solder thickness.The area of center pad soldering has considerable effect to the solder joint reliability,and the size of the area could be increased appropriately in the reflow soldering process.

关 键 词：有限元模拟 可靠性 焊点形态 塑性功 

分 类 号：TG115.28[金属学及工艺—物理冶金]