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MANUFACTURING WITH LASERS: Laser micromachining tips.

Article Excerpt
Laser radiation is a powerful tool for creating microstructures on virtually all types of materials. Depending on boundary conditions, it's suited to machining samples and prototypes, structuring tools, or the direct production of parts. Klaus Vollrath summarises some of the most interesting aspects of a specialist full-day lecture.

'Laser micromachining is a very versatile technology for the production of parts with dimensions in the um to mm range - and containing structures on nm to um scales' explains Dr Nadeem Rizvi, General Manager of Laser Micromachining Ltd (LML); 'the laser beam is a highly directional and controllable tool able to machine almost any material or combination of materials.'

The laser removes material by ablation as a result of absorption of the laser photons. The effect is either thermal (melting, evaporation or eruptive ejection of the material) or chemical (in organic materials chemical bonds can be cracked by interaction with photons having sufficient energy; the disintegrated molecules then evaporate). The laser beam can be precisely controlled in size and energy, and can be used to perform a broad range of tasks such as drilling, shaping, profiling, demetallisation or cleaning.

Wavelength should be matched to workpiece material properties. Especially for plastic materials, spectral transmittance and thus absorption of laser photons can vary for different wavelengths. Eg for polyimide, widely used in medical and biotech applications, good absorption is found in three distinctive wavelength windows matching those of standard laser types: one in the UV...