SPECIAL ISSUE - ORIGINAL ARTICLE Investigation of surface treatment effects in micro-injection-moulding C. A. Griffiths & S. S. Dimov & E. B. Brousseau & C. Chouquet & J. Gavillet & S. Bigot Received: 24 June 2008 / Accepted: 27 February 2009 / Published online: 17 March 2009 # Springer-Verlag London Limited 2009 Abstract Micro-injection-moulding as a replication meth- od is one of the key technologies for micro-manufacture. An important stage in micro-injection-moulding which can affect the accuracy and mechanical properties of the produced components is part de-moulding. During this stage, part-mould forces can cause a variety of defects to micro-parts, including stress marks, deformation, fracture and stretching of the polymer structures. Therefore, in this paper, the effects of different surface treatments on the de-moulding behaviour of parts with micro-features are investigated. In particular, the de-moulding of a represen- tative micro-part was studied as a function of two different tool coatings, diamond-like carbon and silicon carbide, in combination with four process parameters, employing the design of experiment approach. In addition, the results obtained using different combinations of process parame- ters were analysed to identify the best processing conditions in regards to de-moulding behaviour of polycarbonate and acrylonitrile butadiene styrene micro-parts when utilising these two coatings. Keywords Micro-injection-moulding . Surface treatment . De-moulding . Micro-fluidics 1 Introduction Micro-fluidic technologies have found a large variety of new applications in fields such as biotechnology, cytom- etry, medical diagnostics, and micro-chemistry. Significant efforts of the research community are currently focused on developing products that offer point-of-care diagnostic abilities and portable devices such as micro-metre-scale total analysis systems or lab-on-chip systems [1]. The successful development of such new micro-devices is highly dependent on manufacturing systems that can reliably and economically produce large quantities of micro-components. In this context, micro-injection- moulding (IM) of polymer materials is one of the key technologies for micro-manufacturing. Micro-fluidic components produced by micro-IM typically have large overall dimensions but incorporate micro-features less than 200 μm. Thus, such components fall into the type B category of micro-moulded parts according to [2]. In order to achieve an economical and reliable produc- tion of microfluidic parts, it is important to study systematically the factors that affect the micro-IM process. This is due to the fact that for thermoplastic injection moulding, classic replication methods employed to mould macro-parts cannot be applied directly for micro-parts. In particular, micro-moulded components have a high surface to volume ratio (SV R ) and as a result micro-IM is characterised by higher cooling rates. Thus, the possibility of micro-polymer-parts solidifying with states of frozen internal stress is increased [3]. An important step in micro-injection-moulding which can affect the mechanical properties of the produced components is part de-moulding. During the solidifica- tion process of the moulding cycle, the polymer melt shrinks onto the mould cavity walls and features. The Int J Adv Manuf Technol (2010) 47:99–110 DOI 10.1007/s00170-009-2000-4 C. A. Griffiths (*) : S. S. Dimov : E. B. Brousseau : S. Bigot Manufacturing Engineering Centre, Cardiff University, Cardiff CF24 3AA, UK e-mail: griffithsca1@cf.ac.uk C. Chouquet : J. Gavillet French Atomic Energy Commission (CEA), Laboratory of Innovation for New Energy Technologies and Nanomaterials (LITEN), 38054 Grenoble, France