Injection Moulding Using an Exchangeable Si Mould Insert

Abstract

There is need for less expensive and rapid tooling for prototyping components and systems in thermoplastics using microreplication technique such as injection moulding. This paper presents the adaptation of a conventional injection moulding process using a microstructured silicon mould insert. Microstructures with aspect ratio of 4 were produced by a two-step dry etching process of deep reactive ion etching (DRIE) and reactive ion etching (RIE). Cycloolefin copolymer (COC 5013 and 8007) fluidic chips of 560 µm thickness comprising channels of 100 µm depth and width down to 25 µm were manufactured. The injection processing temperature and mould temperature were varied from 265° C to 305° C and 40° C to 190° C respectively to study their effect on the COC replicas. Further, a silicon mould insert with submicronic (400 nm) features was also processed using electron beam lithography and dry-etching, and replicated in polypropylene. Keywords: COC, replica, polymer, micro-injection moulding, electron beam lithography, DRIE, Injection Moulding, Melt flow index, Tensile strength, silicon