On the fabrication of minimizing bulges and reducing the feature dimensions of microchannels using novel CO2 laser micromachining

The shape of a cross-microchannel in polymer is a common pattern in MEMS and can be fabricated using traditional CO2 laser micromachining in air-cooling environment. However, it always suffers some problems during the fabrication process such as bulges, splashes, resolidification and the appearance of a heat affected zone around the rims of channels. In this paper, a novel method of Foil-Assisted CO2 LAser Micromachining (FACLAM) is proposed to fabricate the cross-microchannels in polymethylmethacrylate (PMMA) by significantly diminishing the bulges and the channel's feature sizes. The feature size of the cross-channel can be greatly reduced from 229.1 to 63.6 µm with no clogging effect shown in the cross-junction position. The bulge height of the PMMA microchannel using FACLAM was reduced from the conventional size of 8.2 µm to as small as 0.2 µm. The ANSYS software was also used to analyze the temperature distribution of the PMMA microchannel during machining in air-cooling environment and with foil-mask assistance. The FACLAM approach can improve laser processing quality in air-cooling environment and has the merits of low-cost, easy fabrication and high surface quality.