引线键合力控制系统的优化设计

引线键合采用高纯度金线、铝线连接电子晶片和外围的管脚,是标准的微电子加工和封装的技术。从引线键合运动的角度来说,完整过程包括两种不同的运动状态:自由运动和约束运动。因为系统状态的不连续,在从自由运动的非接触状态到约束运动的接触状态时的阶跃过程,过大的键合力导致“过键合”情况,造成引线键合球的龟裂。所以,引线键合的质量和可靠性很大程度上取决于键合力控制的性能。很多因素都对键合力控性能有很大的影响。在本文中,提出一个具有鲁棒性优化的方法,用来设计高性能的键合力控制系统,在系统参数的波动和不确定性对于性能的影响的情况下,实现引线键合的平滑、稳定的接触阶跃控制。两步走的策略被采用:第一步,建立键合力控制系统的闭环模型;第二步,控制和结构同步鲁棒性优化,设计出高性能的键合力控制系统。

The Optimization Design of Wire Bonding Force Control System

In microelectronic packaging,wire bonding is an important standard technology that provides electrical interconnection between the bonding pads on dies and lead-frames on chip carriers using fine gold wires or aluminum wires.From the view of wire bonding,the whole procedure consists of two states: the free motion and the constrained motion.The bonding force may spillover during the transition of the capillary tip from non-contact to contact state because of discontinuous states,which will result in the "over bonding" that can damage the dies.Many factors have important effects on the controlling performance of bonding force system.Here,a method of using the robust optimization of structure and control concurrently is proposed to design wire bonding force system for achieving smooth transition,where the overshoot of bonding force is minimized and the stable precise bonding force is kept despite of the fluctuation and the uncertain parameters during the process of wire bonding.A two-step strategy has been applied.The first step is to model the close loop control system of wire bonding force.The second step is to optimize these parameters of controller and structure concurrently to achieve the high performance control system of wire bonding force.The results show that it is an effective way to design high performance bonding force control system.