集群磁流变变间隙动压平坦化加工试验研究

为了提高光电晶片集群磁流变平坦化加工效果，提出集群磁流变变间隙动压平坦化加工方法，探究各工艺参数对加工效果的影响规律。以蓝宝石晶片为研究对象开展了集群磁流变变间隙动压平坦化加工和集群磁流变抛光对比试验，通过检测加工表面粗糙度、材料去除率，观测加工表面形貌、集群磁流变抛光垫中磁链串受动态挤压前后形态变化，研究挤压幅值、工件盘转速、挤压频率以及最小加工间隙等工艺参数对加工效果的影响规律。试验结果表明：集群磁流变平坦化加工在施加工件轴向微幅低频振动后，集群磁流变抛光垫中形成的磁链串更粗壮，不但使其沿工件的径向流动实现磨粒动态更新、促使加工界面内有效磨粒数增多，而且在工件与抛光盘之间的加工间隙产生动态抛光压力、使磨粒与加工表面划擦过程柔和微量化，形成了提高材料去除效率、降低加工表面粗糙度的机制。对于2英寸蓝宝石晶电（1英寸=2.54 cm）集群磁流变变间隙动压平坦化加工与集群磁流变抛光加工效果相比，材料去除率提高19.5%，表面粗糙度降低了42.96%，在挤压振动频率1 Hz、最小加工间隙1 mm、挤压幅值0.5 mm、工件盘转速500 r/min的工艺参数下进行抛光可获得表面粗糙度为Ra0.45 nm的超光滑表面，材料去除率达到3.28 nm/min。证明了集群磁流变变间隙动压平坦化加工方法可行有效。

Experimental Study on Cluster Magnetorheological Variable Gap Dynamic Pressure Planarization Finishing

In order to improve the effect of cluster magnetorheological planarization finishing of photoelectric wafer, a method of cluster magnetorheological variable gap dynamic pressure planarization finishing is proposed, and the influence of various process parameters on the polishing effect is explored. Using the sapphire wafer as the research object, a comparative experiment of cluster magnetorheological variable gap dynamic pressure planarization finishing and cluster magnetorheological finishing is carried out. The surface roughness and material removal rate of the finishing surface is detected, the finishing surface morphology and the morphological changes of the magnetic chain string in the cluster magnetorheological polishing pad before and after dynamic squeeze is observed, the influence of squeeze parameters such as squeeze amplitude, workpiece disk rotation speed, squeeze frequency and minimum machining gap on the machining effect is studied. The experiment shows that after the cluster magnetorheological planarization finishing applies the axial low-frequency vibration of the workpiece, the magnetic chain string formed in the cluster magnetorheological polishing pad is thicker, which not only makes the magnetorheological polishing fluid flow along the radial direction of the workpiece to realize the dynamic update of the abrasive particles, promoting the increase of the number of effective abrasive particles in the finishing interface, but also the dynamic polishing pressure is generated in the machining gap between workpiece and polishing disk, and make the abrasive and surface scratching process soft and micro-quantified, which forms a mechanism to improve the removal efficiency of the material and reduce the roughness of the processed surface. Compared with the effect of cluster magnetorheological finishing, the cluster magnetorheological variable gap dynamic pressure planarization finishing has a material removal rate increased by 19.5%, the surface roughness is reduced by 42.96%. Finishing under the process parameters of squeeze vibration frequency 1 Hz, minimum machining gap 1 mm, squeeze amplitude 0.5 mm, workpiece disk rotation speed 500 r/min can obtain an ultra-smooth surface with a surface roughness of Ra 0.45 nm, material removal rate reached 3.28 nm/min. It is proved that the cluster magnetorheological variable gap dynamic pressure planarization finishing is feasible and effective.