Product Code: PIC2008_M404

Experimental Micromachining Results using a Uv Laser with the Laser Microjet�
Authors:
Alexandre Pauchard, Synova Sa; Ecublens Switzerland
Nandor Vago, Synova Sa; Ecublens Switzerland
Nicolas Godde, Synova SA; Ecublens Switzerland
Bernold Richerzhagen, Synova Sa; Ecublens Switzerland
Presented at PICALO 2008

UV wavelengths are interesting for photothermal cutting of materials that have a low absorption coefficient or are transparent at 1064 and 532 nm wavelengths, such as copper, sapphire or glass. The high photon energy of UV lasers plays also a significant role in photochemical machining of polymer materials such as polyimide. In addition to the absorption coefficient, the optical penetration depth varies with wavelength, and different ablation results are expected for ultraviolet, green and infrared lasers. In many cases, the heat diffusion length should not exceed the optical penetration depth, in order to obtain high quality microstructures with clean edges and smooth surfaces. As a result, the duration of the laser pulses needed to be considered as well. The objective of this investigation was to study the compatibility of a 355nm UV laser with the Laser MicroJet® and compare the results of processing difficult-to-machine materials with those obtained with other wavelengths (green and infrared) in terms of quality and throughput. The following materials were tested: pure silicon wafers, low-k wafers, SiC wafers, sapphire wafers, wafers with polyimide coating and polyimide flexible circuits.