Abstract:

This paper presented a structure-electric field coupling method with the cohesive model to analyze the contact and fracture of a conductive particle in COG packaging.Meanwhile,the electric conduction mechanism of COG was also investigated. The results show that the effect of particle's Young modulus on the mechanical and electrical properties of COG packaging is very significant. When the Young modulus is small,the contact surface between the particles and bump/pad is just a circle ring and it makes the joint resistance too large.However, when the Young modulus is large enough, the contact surface will  become a circle. In this case,the resistance will  be smaller a lot, but the greater bonding pressure should be loaded so that the mechanical reliability will become worse. 

Key words: chip on glass (COG), anisotropic conductive film(ACF), cohesive model, contact resistance, multi-physics coupling

摘要：

玻璃覆晶（COG）封装中,导电粒子的非线性力学行为对封装节点的电性能精确建模提出了挑战。提出了一种结合内聚力模型的位移-静电场顺序耦合方法,分析了玻璃覆晶封装中不同弹性模量导电粒子在键合压力和温度共同作用下的破裂与接触行为,探讨了节点电阻的形成机理与非线性变化规律,揭示了导电粒子弹性模量对节点电阻和机械可靠性的影响规律,进而提出了导电粒子最优弹性模量范围。研究结果表明：当弹性模量较小时,导电粒子与凸点/焊盘的接触面为圆环,使得节点电阻过大;随着弹性模量的逐渐增大,接触面会变为实心圆,但封装节点机械可靠性变差。

关键词: 玻璃覆晶, 各向异性导电膜, 内聚力模型, 接触电阻, 多物理场耦合