Surface roughness and erosion rate of abrasive jet micro-machined channels: Experiments and analytical model

Abrasive jet micro-machining (AJM) uses a high velocity particle jet to erode features in target substrates for a variety of applications, including micro-electro-mechanical and micro-fluidic device fabrication. The roughness of micro-channels for micro-fluidic applications made using AJM can affect fluid flow phenomena such as separation efficiency, electro-osmotic mobility and solute dispersion. Moreover, surface roughness plays a major role in micro-scale adhesion contact in MEMS and light scattering in optoelectronics devices. This paper presents experimental data on the effect of particle size, velocity, and angle of attack on the roughness of unmasked channels machined in borosilicate glass using AJM. Single impact experiments were conducted to quantify the damage due to the individual alumina particles. Based on these observations, the assumed location of lateral crack initiation in a relatively simple analytical model from the literature was modified, and used to predict the roughness and erosion rate. The previous model, which calculated an areal roughness, was also modified to yield a 2D linear value of Ra so that it could be compared with linear profilometer scans. This modified model predicted the steady-state roughness and erosion rate of unmasked channels with average errors of 36% and 73%, respectively.