倒装焊芯片封装微通孔的一种失效机理及其优化方法

A Failure Mechanism and Its Optimization Method for Flip-Chip Package Micropore

摘要:

随着晶圆工艺节点的发展,封装集成度越来越高,封装有机基板的线宽和线距逐步减少,微通孔的数量增加,微通孔的孔径减少。球栅阵列(BGA)封装有机基板的微通孔失效一直是影响 高性能和高密度芯片封装可靠性的主要问题。针对有机基板微通孔失效的问题,通过温度循环可靠性试验、有限元分析方法、聚焦离子束、扫描电子显微镜以及能谱仪等表征手段,系统研究了-65 ℃~ 150 ℃与-55 ℃~125 ℃ 500次温度循环加载条件下倒装焊的失效模式。结果表明,在-65 ℃~ 150 ℃ 温度循环条件下,有机基板微通孔由温度循环疲劳应力而产生微通孔分层,仿真表明-65 ℃~ 150 ℃下基板平均等效应力增加约8 MPa；通过改善散热盖结构,等效应力降低了21.4%,且能通过-65 ℃~150 ℃ 500次温度循环的可靠性验证,满足高可靠性的要求。

Abstract:

With the development of wafer process nodes, the package integration is increasingly higher. As a result, the linewidth and spacing of the packaged organic substrate gradually decrease, the number of micropore increases, and its pore diameter decreases. The micropore failure of organic substrate in ball grid array (BGA) packaging has always been a major problem affecting the reliability of high performance and high density chip packaging. Aiming at the micropore failure in organic substrate, the failure modes of flip welding under 500 times of temperature cycle loading at -65 ℃ - 150 ℃ and -55 ℃ - 125 ℃ were studied systematically by means of temperature cycle reliability test, finite element analysis, focused ion beam, scanning electron microscope and energy spectrometer. The results show that the micropores of organic substrates are delaminated due to temperature cyclic fatigue stress under the condition of temperature cycle from-65 ℃ to 150 ℃. The simulation results show that the average equivalent stress of the substrate increases by about 8 MPa. Subsequently, the structure of the heat dissipation cover is improved. After the improvement, the equivalent stress is reduced by 21.4%, and it can pass the reliability verification of 500 times thermal cycling from -65 ℃ to 150 ℃, which meets the requirements of high reliability.