Integral approach for production of thermoplastics microparts by injection moulding

Abstract

Over the last decades, microinjection moulding of thermoplastics has gained a pertinent place on the market of electronic equipment and a broad range of the mechanical aids. However, when size of component drops to the micro-level, the assumptions of the conventional injection moulding cease to describe complex rheological and thermo-mechanical behaviour of the polymer in the microcavity. Miniaturization implies a number of challenges which could only overcome by a series of profound modifications of the conventional injection moulding machine and tools. In the scope of this review, a brief discussion of the strategies applied for adaptation of the conventional injection moulding process to microscale will be introduced. Further, a particular attention will be given to the process/tool/polymer interaction and its influence on the quality signatures of micromoulded parts. In addition an overview of the rheological models of the polymer flow at microcavities and the numerical simulation of the microinjection moulding will then be addressed. Quality evaluation of the micromoulded parts require considering both polymer morphology assessment and final mechanical properties. At microscale, the acquisition of the latter is unlikely by means of conventional mechanical testing, therefore, a brief summary of the mechanical testing for micropolymeric parts will be presented. In order to further evaluate the quality signatures of micromoulded parts an overview of the combined thermo-rheological and structural analysis to link processing history and mechanical solicitations of the part to its short- and long-term performance is also presented here.