The packaging of membranes adjacent to microchannels is of growing interest. To facilitate this, microgrooves were laser machined into a polyetherimide (PEI) embossing tool to produce sealing bosses for embossed polycarbonate (PC) microchannel laminae. Laser ablation was conducted using a Nd:YAG laser at 355 nm. Sealing bosses were produced and characterized by hot embossing of PC sheet using the PEI tool as a master. Sealing bosses of around $10{mu}m$, in height were successfully reproduced. Laser power between 0.3 and 0.7 Wand scan speeds of 200 to 400 mm/s were found to be most important for controlling the boss height. As expected, the boss width was found to be dependent on the laser beam diameter. The effect of specimen flatness was found to be negligible.