引线间距对QFP焊点的可靠性影响的有限元分析

Effect of leads pitch on soldered joint reliability of QFP device with finite element analysis

采用有限元方法分别对具有相同引线间距和不同封装类型的QFP器件的焊点残余应力进行了数值模拟计算分析。结果表明,焊点根部、焊趾部位以及引线和焊点交界处为应变集中区域,该三处将可能成为焊点发生破坏区域,在焊点根部的应力值是最大,所以在焊点根部最容易发生破坏。对结果进行分析比较,从应力曲线图可以看出,由于残余应力累积的原因,应力具有迭加性;在引线数目相同的QFP器件中,TQFP64焊点的应力最小,VQFP64次之,SQFP64最大。在引线间距相同的QFP器件中,QFP64焊点的应力最小,QFP44居中,QFP32最大;同时与QFP100比较可知,高密度细间距器件的焊点可靠性更高。

Finite element method was used to simulate the residual stress in soldered joints of QFP device with the same distance and number of leads,respectively.The results indicated that the stress concentration areas in soldered joint locate at the heel and toe of the soldered joint,as well as at the area between the lead and the soldered joint;the largest value of the stress was in the heel of the soldered joints,which would be the weakest area of the joints.Through the comparison of these results,especially the ...