4M Knowledge base - papers

M.R.H Knowles, G. Rutterford, D. Karnakis, A. Ferguson
Oxford Lasers Ltd, Unit 8, Moorbrook Park, Didcot, OX11 7HP, UK

Abstract

Laser micro-processing is an enabling technology that facilitates component minaturization and improved performance characteristics. It is being applied across many industries – semiconductor, electronics, medical, automotive, aerospace, instrumentation, and communications. 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 minimize the degree of melting involved and short pulse lasers show certain advantages in this respect. We discuss the benefits of high laser intensity (GW/cm)^2 on 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 can be exploited to our advantage in particular for high aspect ratio micro-drilling and micro-cutting.

C. Blattert (a), C. Müller (b), H. Reinecke (a),(b)

(a) Hahn-Schickard-Gesellschaft e. V. Institute for Micromachining and Information Technology (HSG-IMIT),Villingen-Schwenningen, Germany
(b) Laboratory for Process Technology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany

Abstract

Piracy and counterfeiting as well as retraceability demands of products such as plastic parts or tablets require new and innovative methods for unique product identification. An opportunity is the placement of microstructured codes in moulding tools. These tools are often made from materials that do not allow for highly precise micromachining by traditional technologies. Electrochemical machining (ECM) is a method for structuring construction materials such as steel or titanium. The current paper presents a new technology for the fabrication of microstructured tool electrodes for electrochemical machining by using highly doped silicon as electrode material. A simple and low priced fabrication of microstructured silicon electrodes with locally isolated areas is demonstrated by using wellestablished silicon processing technologies. Prototypes based on this new tool electrode technology are fabricated. Therewith electrochemical machining of microstructures in stainless steel is successfully demonstrated. Machining gaps down to 10 μm and average surface roughness of 60 nm are achieved. Typical rates of removal between 60 - 240 μm/min are reached. The local isolation of electrode areas advances the machining accuracy.

G. Lalev (1), P. Petkov (1), N. Sykes (2), V. Velkova (1), S. Dimov (1), D. Barrow (2)

(1) Manufacturing Engineering Centre, Cardiff University, Newport Road,Cardiff, CF24 3AA, UK
(2) metaFAB, Cardiff University, Newport Road, Cardiff, CF24 3AA, UK

Abstract

A cost effective methodology for pattering of Nano Imprint Lithography (NIL) templates with different length scale features is proposed. The approach relies on selecting the optimum processing window of different technologies for cost effective micro and nano patterning. Very promising results were obtained when first fused silica templates were structured by F2 laser ablation at 157 nm without inducing phase transformation of the material. It was demonstrated that nanoscale features and complex 3D microscale features could be machined with a Focused Ion Beam (FIB) over the existing topography produced by laser ablation. Thus, a large area (up to several square centimetres) of the NIL templates is easily patterned with micro- and even meso-scale features by laser ablation while nano- and micro-scale features could be introduced by FIB machining.