Product Code: ICA11_1002

Recoil Pressure and Surface Temperature in Laser Drilling
Authors:
Matthieu Schneider, Arts et Métiers Paristech; Paris France
Jérémie Girardot, Arts et MéTiers Paristech; Paris France
Laurent Berthe, Arts et Métiers Paristech; -
Presented at ICALEO 2011

To drill sub-millimeters holes one of the way is laser drilling. Laser drilling is a well-established industrial process from decades; however several fundamental questions are still unsolved about the physical understanding of the laser matter interaction. A sequential description of the laser drilling process can be made as following. The irradiated surface is heated by absorption of laser energy. Once the surface temperature is higher than the vaporization one, a vapor flow is normal to the local surface. The recoil pressure generated by the evaporation, exerts a force on the melted surface and starts expelling the melt layer out of the hole by the side. A Mach shock disc appears in the flow, the ejected vapor flow is then supersonic. Finally, The surface goes deeper in the target. This paper relates to an original way for measuring recoil pressure and surface temperature on target in laser drilling process from the observations of the supersonic vapor flow. From these observations and thanks one can correlate the surface temperature, the recoil pressure on the melt layer and the Mach number in the supersonic jet with the incident intensity. Results show below 25 MW.cm-2 of incident intensity the highest surface temperature reached, is in the range of 5000K, with a Mach number of 5 and a recoil pressure about 150 bars.