Micro-machining of metals, ceramics and polymers using nanosecond lasers

Laser micro-processing is an enabling technology that facilitates component miniaturisation and improved performance characteristics. It is being applied across many industries, including semiconductors, electronics, medical, automotive, aerospace, instrumentation and communications. The laser ablation of metals, ceramics and polymers is a complex process and the exact nature of the interaction is specific to the material and laser processing parameters used. Ablation is usually a combination of evaporation and melt expulsion. In order to achieve the highest quality results, it is often desirable to minimise the degree of melting involved and short-pulse lasers show certain advantages in this respect. We discuss the benefits of high laser intensity (GW/cm2) on the target for efficient laser micro-fabrication in metals and ceramics. At such high irradiance conditions, material properties are approaching their critical limits and ablation mechanisms are becoming even more complicated, but this can be exploited to our advantage, in particular, for high-aspect-ratio micro-drilling and micro-cutting. Laser micro-milled 2.5D structures were generated in alumina, tungsten, steel and polyimide. Volume removal rates are presented for the different materials for different laser fluences.