芯片级封装互连体在电流作用下的损伤行为

Degradation mechanisms of chip scale package solder interconnects by electrical loading

随着电子封装互连焊点尺寸的不断减小,其电流密度越来越大,产生大量的焦耳热,焊点在服役中受到热场和电场共同作用,导致焊点的熔断失效。本文在常温环境和低温环境下分别加载1.0 A恒定电流的作用下,分析了CSP(Chip Size Package,即芯片级封装)样品的失效过程以及在不同服役条件下的Sn-3.8Ag-0.7Cu微焊球横截面的组织变化。得出互连体的失效行为分为三个阶段,并观察到互连焊点的界面处化合物Cu6Sn5在PCB(Printed circuit board,即印刷电路板)端界面处的生长和芯片端UBM(Under Ball Metal,即凸点下金属层)层Cu的消耗,同时得到降低其环境温度抑制CSP样品失效的结论。

In microelectronic packaging, as the size of the solder connection becomes smaller, the current density increased continuously, which generates great joule heat, and the temperature of components is raised. As a result, the solder joints are subject to the combined action of both electric field and thermal field,leading to the failure of the solder joint. This paper analyzes the failure of CSP sample,and the cross- sectional micro-structural transformation of Sn-3.8Ag - 0. 7Cu solder joints in different service situations, under 1.0 A electric current at room temperature and low temperature. There are three stages in the failure behavior of solder interconnects. The paper observes the growth of Cu6 Sn5 compounds of PCB side interface and the degradation of Cu of chip side interface in the solder joint, and draws the conclusion that the failure of the solder interconnects was suppressed by decreasing the temperature of the solder joints.