基于平面抛光的回收QFN芯片引脚氧化层批量去除一致性仿真分析

Simulation Analysis of Batch Removal Consistency for Oxide Layers on Reclaimed QFN Chip Pins Based on Planar Polishing

摘要: 针对回收的QFN芯片，本文首次提出采用平面抛光方式实现引脚氧化层的批量去除。通过对单颗磨粒相对工件的运动轨迹的研究，得出了抛光工装正弦偏摆时磨粒相对于工装的运动方程。利用MATLAB对抛光参数进行仿真分析。仿真结果表明工装初始相位β对抛光轨迹均匀性无显著影响。偏心轴与抛光盘中心距e对抛光轨迹均匀性的影响较为有限，但是会影响加工效率，且e越大加工效率越高。偏心轴与工装中心距q对抛光轨迹均匀性具有显著影响，增大q能够有效提升抛光轨迹的均匀性，当q = 15 mm时均匀性最好。小数速比的轨迹均匀性要明显优于整数速比，有限小数和无限循环小数速比对非均匀性系数的影响无明显差异。因此在实际加工过程中应将速比设置为小数。

Abstract: For recycled Quad Flat No-leads (QFN) chips, this paper proposes, for the first time, a plane polishing method for the batch removal of the oxide layer on the leads. By studying the motion trajectory of a single abrasive particle relative to the workpiece, the equation of motion for the particle relative to the fixture was derived for a sinusoidal swing motion of the polishing fixture. MATLAB was used to simulate and analyze the polishing parameters. The simulation results indicate that the initial phase of the fixture has no significant impact on the uniformity of the polishing trajectory. The distance between the eccentric shaft and the center of the polishing plate (denoted as “e”) has a limited effect on the trajectory uniformity. However, it influences machining efficiency, with a larger “e” leading to higher efficiency. The distance between the eccentric shaft and the center of the fixture (denoted as “q”) significantly affects the trajectory uniformity. Increasing this distance effectively improves the uniformity, with the best uniformity achieved when q = 15 mm. A decimal speed ratio yields better trajectory uniformity than an integer speed ratio. Furthermore, there is no significant difference in the effect on the non-uniformity coefficient between finite decimal and infinite repeating decimal speed ratios. Therefore, in practical machining applications, the speed ratio should be set to a decimal value.