Papers by Author: Wei Long Cong

Abstract: Sapphire, widely used in high-speed integrated-circuit chips, thin-film substrates, and various electronic components, is regarded as one of the most difficult to cut materials owing to its great hardness and low fracture toughness. Rotary ultrasonic machining (RUM) has been regarded as an effective processing method for hard and brittle materials. In this paper, RUM process is introduced into the drilling of sapphire for the first time. The feasibility to machine sapphire using RUM is studied. Moreover, results of a designed experimental study into RUM of sapphire are presented to discuss the main effects as well as interaction effects of process parameters (ultrasonic power, spindle speed, and feedrate) on outputs. The process outputs investigated include cutting force and edge chipping size.

Abstract: Lapping is an important material-removal process for manufacturing of substrate wafers. Objectives of lapping include removing subsurface damage in sliced wafers, thinning wafers to target thickness, and achieving a high degree of parallelism and flatness of wafer surfaces. This paper reviews the literature on lapping of substrate wafers. It presents reported experimental results on effects of input parameters (lapping pressure, plate rotation speed, abrasive grain size, slurry concentration, and slurry flow rate) on material removal rate and surface roughness.