Mould redesign and analysis for the production of a micro-accelerometer

Abstract

In this paper we present an alternative fabrication method based on polymeric materials and technologies for three-axis thermal accelerometers. The device is composed by four microinjected parts forming an external structure responsible for the coupling and sealing of a polymeric membrane. The membrane contains and protects the heater and thermoresistors and is fabricated by microtechnologies. The fabrication process was successful although some issues were noticed in the mould during the microinjection process. Regarding the ejection side, a redesign was done to first assure the locking of the micro-parts on the movable side of the mould and second to improve the extraction of the parts avoiding its deformation. Overheating of the mould and polymer freezing on the injection nozzle were the main issues found on the injection side of the mould. Three different injection nozzle designs and two different fabrication materials were analyzed and simulated. The results show that an intermediate injection nozzle design using Ampcoloy 940® as construction material can improve the maintenance of the established temperature values for both mould and injection nozzle.